Pigment, process for producing the same and paint using the same

BACKGROUND OF THE INVENTION
The present invention relates to a pigment, a process for producing the pigment and a paint using the pigment, and more particularly, relates to a pigment suitably used for not only organic solvent-type paints but also water-based paints and having excellent dispersion facility, dispersion homogeneity and dispersion stability, a process for producing the pigment, and a paint produced by using the pigment.
Hitherto, inorganic pigments have been used as coloring agents for paints by dispersing these pigments in vehicle, because they are excellent in chemical resistance, weather resistance or the like, and has a high stability.
In recent years, there is an increasing demand for high performance and high quality of coating films obtained by applying a paint on various substrates and drying the applied paint. In order to meet such a demand, there have been strongly required improvements in properties of the pigment which are considered the most influential factor on the qualities of the coating films such as brightness of color tone, tinting strength, brightness and gloss. Further, it has been required that the pigment used in the paint shows an excellent dispersion facility, dispersion homogeneity and dispersion stability in a vehicle for the paint.
This fact is pointed out, for instance, in "The Latest Technique for Pigment Dispersion", published by the Technical Information Society in 1993, on page 15: ". . . Pigment is never used singly and the pigment is always used after dispersed in a binder resin, solvent or other suitable material. The fine pigment particles need to be easily dispersible and also homogeneously dispersed in the binder for obtaining a clear color tone, high tinting strength and other desired performance. However, since the more the fine particles, the less the stability thereof becomes, it is a matter of great account to maintain stable dispersibility of the pigment particles. . . . ", and ". . . The properties required for the pigment may be defined and classified as follows from the various viewpoints. Dispersibility is classified as a matter that affects the physical properties, but the dispersibility also has close relation to and an influences the optical, chemical and specific functional properties. Namely, the improvement of dispersibility of the pigment for allowing uniform dispersion not only to mean enhancement of clearness of color tone, tinting strength, brightness and gloss of the coating films, but also to lead to improvement of chemical properties such as fastness, and workability. . . . "
Paints are divided into two types depending on the solvent used: organic solvent-type paints using an organic solvent as main solvent and water-based paints using water as main solvent.
In recent years, water-based paints have been considered favorable in terms of safety, hygiene and environmental protection, because the water-based paints have no serious atmospheric pollution problem, are more advantageous in saving of resource and energy, and also are easy to handle, thereby causing little risk of a fire.
However, since the dispersion mechanism of the pigment particles in a water-based paint is different from that in the conventional organic solvent-type paints, it is impossible to disperse the pigment particles in a vehicle by the same dispersion techniques as used for the organic solvent-type paints. An aqueous resin (color developer) is used in a water-based paint. Although an organic solvent-type resin (color developer) exists in a dissolved state with a certain spread, the aqueous resin exists mostly in the form of particles such as emulsion polymer particles or colloidal particles, resulting in difficulty in exhibiting steric hindrance effect of the resin, and therefore, deteriorated dispersibility of the pigment particles in the resin. Consequently, it becomes a problem how the pigment particles should be dispersed in the vehicle and how long it should take until effected, that is, dispersion facility and dispersion homogeneity of pigment particles becomes the problem of primary consideration. Further, the dispersion stability comes into problem since the pigment particles tend to reagglomerate due to interaction between dispersed pigment particles and the aqueous resin particles.
Therefore, it has been strongly required to provide pigment particles which can sufficiently function for not only the organic solvent-type paints but also the water-based paints, and are excellent in dispersion facility, dispersion homogeneity and dispersion stability.
Conventionally, in order to improve dispersibility of pigment particles in vehicle, it has been proposed to coat pigment particle surfaces with various kinds of inorganic or organic compounds.
For example, in Japanese Patent Application Laid-open (KOKAI) No. 5-225552(1993), there are described ferromagnetic metal fine particles whose surfaces are treated with 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid) as a 4-membered ring compound, and a magnetic recording medium using the particles. In Japanese Patent Application Laid-open (KOKAI) No. 5-225553(1993), there are described ferromagnetic metal fine particles whose surfaces are treated with aromatic organic acids having an anthraquinone skeleton such as alizarin, and a magnetic recording medium using the particles.
Also, in Japanese Patent Application Laid-open (KOKAI) No. 8-120191(1995) which corresponds to U.S. Pat. No. 5,686,012, there are described colored inorganic particles whose surfaces are coated with squaric acid and then with polysiloxane modified with polyether or the like.
In addition, various methods have been attempted to modify surfaces of the pigment particles with alcohol or the like. For instance, there have been proposed a method of imparting a lipophilic property to metal oxide particles by boiling the particles in alcohols having not more than 8 carbon atoms (Japanese Patent Application Laid-open (KOKAI) No. 48-100398(1973)), a method of improving the dispersibility of hydrophilic pigment particles by adding an aliphatic alcohol and non-polar solvent to the particles, and then heating the mixture while stirring to fix the alcohol on surfaces of the particles (Japanese Patent Application Laid-open (KOKAI) No. 49-97822(1974)), a method of surface-treating metal oxide particles by chemically bonding ethylene glycol or the like on surfaces of the metal oxide particles and then reacting unreacted alcoholic hydroxyl group of the ethylene glycol with an ethylenically unsaturated bond-containing compound (Japanese Patent Publication (KOKOKU) No. 57-1483(1982)), a method of surface-treating metal oxide particles by reacting the monovalent alcohol-treated particles with a polyvalent alcohol to conduct an ester exchange reaction therebetween (Japanese Patent Application Laid-open (KOKAI) No. 4-92803(1992)), or the like.
Furthermore, there have been proposed inorganic pigment particles whose surfaces are coated with a surface active reaction product obtained by reacting a polyol having 3 to 4 hydroxyl groups and 3 to 7 carbon atoms such as trimethylol propane, with alkylene oxide in an amount of about 1 to about 5 moles per one hydroxyl group of the polyol (Japanese Patent Publication (KOKOKU) No. 53-18539(1978)), or the like.
However, any of these conventional pigment particles cannot exhibit a sufficient dispersibility when used in water-based paints.
That is, the above-mentioned ferromagnetic metal fine particles described in Japanese Patent Applications Laid-open (KOKAI) Nos. 5-225552(1993) and 5-225553(1993) whose surfaces are treated with the squaric acid or the aromatic organic acid having an anthraquinone skeleton (such as alizarin) cannot exhibit a sufficient negative charging property when used as pigment particles in water-based paints.
The above-mentioned pigment particles described in Japanese Patent Application Laid-open (KOKAI) No. 8-120191(1995) have an upper coating layer comprising polysiloxane. Since the polysiloxane is a relatively expensive treating agent and since it is necessary to conduct the coating treatment at a high temperature due to a high molecular weight thereof, the pigment particles are disadvantageous from industrial viewpoints.
The pigment particles described in Japanese Patent Applications Laid-open (KOKAI) Nos. 48-100398(1973), 49-97822(1974) and 4-92803(1992) and Japanese Patent Publication (KOKOKU) No. 57-1483(1982) are surface-treated mainly for imparting a lipophilic property thereto such that the particles can be used in organic solvent-type paints. Therefore, when these particles are used in water-based paints, sufficient dispersibility of the particles therein cannot be achieved.
Further, the inorganic particles described in Japanese Patent Publication (KOKOKU) No. 53-18539(1988) are coated with the surface active reaction product to facilitate the dispersion of the particles in both aqueous and organic solvents. However, as described in Comparative Examples hereinafter, the inorganic particles cannot show a sufficient dispersibility in water-based paints.
In consequence, it has been still strongly demanded to provide pigment particles which can show excellent dispersion facility, dispersion homogeneity and dispersion stability when used in not only organic solvent-type paints but also water-based paints.
As a result of the present inventors' earnest studies, it has been found that by mixing pigment particles with squaric acid in water or alcohol as a dispersing solvent, followed by filtering and drying, to form a lower coat comprising squaric acid on at least a part of surface of the pigment particle, and then mixing the squaric acid-coated particles with at least one kind of alkylene glycol represented by the general formula: C.sub.n H.sub.2n (OH).sub.2, wherein n is an integer of 2 to 10, to form an upper coat comprising alkylene glycol on at least a part of the said coated pigment particle, the obtained particles can show excellent dispersion facility, dispersion homogeneity and dispersion stability in paints, especially in water-based paints. The present invention has been attained on the basis of this finding.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a pigment which is excellent in dispersion facility, dispersion homogeneity and dispersion stability in paints, especially in a water-based paint.
It is another object of the present invention to provide a paint, especially a water-based paint which can show an excellent storage stability due to excellent dispersion facility, dispersion homogeneity and dispersion stability of pigment in a paint base material in addition to excellent brightness of color tone, tinting strength, brightness and gloss.
To accomplish the aim, in a first aspect of the present invention, there is provided a pigment comprising:
pigment particle as core particle;
a lower coat formed on at least a part of surface of the pigment particle, comprising (a) squaric acid, (b) polyol having an anthraquinone skeleton represented by the general formula (I): ##STR2## wherein m is an integer of 0 to 4, n is an integer of 0 to 4 and m+n is an integer of 2 to 4,
or (c) a mixture of the squaric acid and the polyol having an anthraquinone skeleton represented by the general formula (I); and
an upper coat formed on at least a part of surface of the obtained particle, comprising at least one alkylene glycol represented by the general formula (II):
C.sub.q H.sub.2q (OH).sub.2 (II)
wherein q is an integer of 2 to 10.
In a second aspect of the present invention, there is provided a paint comprising a paint base material and a pigment comprising:
pigment particle as core particle;
a lower coat formed on at least a part of surface of the pigment particle, comprising (a) squaric acid, (b) polyol having an anthraquinone skeleton represented by the general formula (I): ##STR3## wherein m is an integer of 0 to 4, n is an integer of 0 to 4 and m+n is an integer of 2 to 4,
or (c) a mixture of the squaric acid and the polyol having an anthraquinone skeleton represented by the general formula (I); and
an upper coat formed on at least a part of surface of the obtained particle, comprising at least one alkylene glycol represented by the general formula (II):
C.sub.q H.sub.2q (OH).sub.2 (II)
wherein q is an integer of 2 to 10.
In a third aspect of the present invention, there is provided a process for producing a pigment, comprising:
mixing as a dispersing solvent water or alcohol, pigment particles with squaric acid, polyol having an anthraquinone skeleton represented by the general formula (I): ##STR4## wherein m is an integer of 0 to 4, n is an integer of 0 to 4 and m+n is an integer of 2 to 4,
or a mixture of squaric acid and polyol having an anthraquinone skeleton represented by the general formula (I), followed by filtering and drying, to form a lower coat comprising squaric acid, polyol having an anthraquinone skeleton represented by the general formula (I) or the mixture thereof on at least a part of surface of the pigment particle; and
a second step of mixing the obtained pigment particles with at least one alkylene glycol represented by the general formula (II):
C.sub.q H.sub.2q (OH).sub.2 (II)
wherein q is an integer of 2 to 10,
to form an upper coat comprising the alkylene glycol on at least a part of surface of the obtained particle.
DETAILED DESCRIPTION OF THE INVENTION
First, the pigment according to the present invention is described.
The pigment used as core particles in the present invention is composed of the following various known pigment particles.
Specific examples of the core pigment particles may include white pigment particles such as zinc white (ZnO), white lead (2PbCO.sub.3.Pb(OH).sub.2), basic lead sulfate (3PbSO.sub.4.PbO.about.2PbSO.sub.4.PbO), lead sulfate (PbSO.sub.4), lithopone (ZnS+BaSO.sub.4), zinc sulfide (ZnS), titanium dioxide (TiO.sub.2) and antimon oxide (Sb.sub.2 O.sub.3); black pigment particles such as carbon black (C), graphite (C) and black iron oxide (FeO.sub.x.Fe.sub.2 O.sub.3 (0<x.ltoreq.1)); yellow pigment particles such as chrome yellow (PbCrO.sub.4), zinc yellow (ZnCrO.sub.4), barium chromate (BaCrO.sub.4), cadmium yellow (CdS), yellow iron oxide hydroxide (FeOOH.nH.sub.2 O), ochre (Fe.sub.2 O.sub.3.SiO.sub.2.Al.sub.2 O.sub.3), titan yellow (TiO.sub.2.NiO.Sb.sub.2 O.sub.3), lead cyanamide (Pb(CN).sub.2) and calcium plumbate (Ca.sub.2 PbO.sub.4); orange pigment particles such as chrome orange (PbCrO.sub.4.PbO) and chrome vermilion (PbCrO.sub.4.PbMoO.sub.4.PbSO.sub.4); brown pigment particles such as brown iron oxide (.gamma.-Fe.sub.2 O.sub.3) and umber (Fe.sub.2 O.sub.3 +MnO.sub.2 +Mn.sub.3 O.sub.4); red pigment particles such as red iron oxide (.alpha.-Fe.sub.2 O.sub.3), red lead (Pb.sub.3 O.sub.4), vermilion (HgS), cadmium red (CdS+CdSe), cadmium mercury red (CdS+HgS) and antimony vermilion (2Sb.sub.2 S.sub.3.Sb.sub.2 O.sub.3 or Sb.sub.2 S.sub.3.Sb.sub.2 O.sub.3); violet pigment particles such as cobalt violet deep (Co.sub.3 (PO.sub.4).sub.2, Co.sub.3 (PO.sub.4).sub.2. 8H.sub.2 O), cobalt violet light (Co.sub.3 (AsO.sub.4).sub.2, Co.sub.3 (AsO.sub.4).sub.2. 8H.sub.2 O) and manganese violet (Mn.sub.2 (PO.sub.4).sub.3, (NH.sub.4).sub.2 Mn(P.sub.2 O.sub.7).sub.2); blue pigment particles such as ultramarine (3NaAl.SiO.sub.4.Na.sub.2 S.sub.2, 2(Na.sub.2 O.Al.sub.2 O.sub.3.2SiO.sub.2).Na.sub.2 S.sub.2), Prussian blue (Fe.sub.4 [Fe(CN).sub.6 ].sub.3.nH.sub.2 O), cobalt blue (CoO.nAl.sub.2 O.sub.3 (n=2 to 3)) and cerulean blue (CoO.nSnO.sub.2.mMgO (n=1.5 to 3.5, m=2 to 6)); and green pigment particles such as chrome green (prussian blue +chrome yellow), zinc green (zinc yellow+prussian blue), chromium oxide green (Cr.sub.2 O.sub.3), veridian (Cr.sub.2 O(OH).sub.4), emerald green (Cu(CH.sub.3 CO.sub.2).sub.2.3CuO (AsO.sub.2).sub.2) and cobalt green (CoO.ZnO.MgO).
Among these pigment particles, zinc white (ZnO), white lead (2PbCO.sub.3.Pb(OH).sub.2), titanium dioxide (TiO.sub.2), antimon oxide (Sb.sub.2 O.sub.3), black iron oxide (FeO.sub.x.Fe.sub.2 O.sub.3 (0<x.ltoreq.1), chrome yellow (PbCrO.sub.4), zinc yellow (ZnCrO.sub.4), cadmium yellow (CdS), yellow iron oxide hydroxide (FeOOH.nH.sub.2 0), titan yellow (TiO.sub.2.NiO.Sb.sub.2 O.sub.3), chrome vermilion (PbCrO.sub.4.PbMoO.sub.4.PbSO.sub.4), brown iron oxide (.gamma.-Fe.sub.2 O.sub.3), red iron oxide (.alpha.-Fe.sub.2 O.sub.3), cadmium red (CdS+CdSe), cadmium mercury red (CdS+HgS), cobalt blue (CoO.nAl.sub.2 O.sub.3 (n=2 to 3)), chrome green (prussian blue+chrome yellow) and chromium oxide green (Cr.sub.2 O.sub.3) are preferred, because the effect of the present invention can be effectively accomplished. Further, the iron oxide-based particles such as black iron oxide (Fe.sup.2+.sub.x Fe.sup.3+.sub.(8-2x)/.sub.3 O.sub.4 (0<x.ltoreq.1), red iron oxide (.alpha.-Fe.sub.2 O.sub.3) and brown iron oxide (.gamma.-Fe.sub.2 O.sub.3), yellow iron oxide hydroxide (FeOOH.nH.sub.2 O), titanium dioxide (TiO.sub.2), chrome yellow (PbCrO.sub.4) and chromium oxide green (Cr.sub.2 O.sub.3) are more preferred.
Especially, the iron oxide-based particles such as brown iron oxide (.gamma.-Fe.sub.2 O.sub.3), black iron oxide (FeO.sub.x.Fe.sub.2 O.sub.3 (0<x.ltoreq.1) and red iron oxide (.alpha.-Fe.sub.2 O.sub.3), and yellow iron oxide hydroxide (FeOOH.nH.sub.2 O) are even more preferred.
The above-mentioned various known pigment particles used as core particles in the present invention have an average particle diameter of usually 0.01 to 10 .mu.m, preferably 0.1 to 3 .mu.m, and may be of any suitable shape such as acicular shape, spindle-like shape, plate-like shape, spherical shape, cubic shape, octahedral shape or granular shape. The BET specific surface area of these particles may be in the range of usually 0.1 to 80 m.sup.2 /g, preferably 1 to 60 m.sup.2 /g.
Especially, in the case of granular particles, the average particle diameter of the iron oxide-based particles or the yellow iron oxide hydroxide particles used in the present invention is usually 0.01 to 10 .mu.m. In view of tinting strength and brightness, the average particle diameter thereof is preferably 0.05 to 3.0 .mu.m, more preferably 0.1 to 0.5 .mu.m.
In the case of acicular-like or spindle-like particles, the average major axial diameter of the iron oxide-based particles or the yellow iron oxide hydroxide particles is usually 0.05 to 20 .mu.m and the average aspect ratio (average major axial diameter/average minor axial diameter) thereof is usually 2:1 to 20:1. In view of tinting strength and brightness, the average major axial diameter thereof is preferably 0.05 to 5.0 .mu.m, more preferably 0.1 to 1.0 .mu.m, and the average aspect ratio (average major axial diameter/average minor axial diameter) thereof is preferably 2:1 to 15:1, more preferably 2:1 to 10:1.
In addition, in the case of plate-like particles, the average particle diameter (plate surface diameter) of the iron oxide-based particles or the yellow iron oxide hydroxide particles is usually 0.01 to 20.0 .mu.m, and the average thickness thereof is usually 0.005 to 2.0 .mu.m. In view of tinting strength and brightness, the average particle diameter (plate surface diameter) is preferably 0.05 to 15.0 .mu.m, more preferably 0.1 to 10.0 .mu.m, and the average thickness is preferably 0.007 to 1.5 .mu.m, more preferably 0.01 to 1.0 .mu.m.
The pigment according to the present invention comprises the above-mentioned various known pigment particles as core particles, a lower coat formed on surfaces of the core particles, comprising (a) squaric acid, (b) polyol having an anthraquinone skeleton or (c) both squaric acid and polyol having an anthraquinone skeleton, and an upper coat formed on the lower coat, comprising alkylene glycol.
The coating amount of the squaric acid on surfaces of the core particles is preferably 0.01 to 10% by weight (calculated as C), more preferably 0.02 to 5% by weight based on the total weight of the pigment. When the coating amount of the squaric acid is less than 0.01% by weight, the effect of fixing the upper coat comprising alkylene glycol thereon in the next step may not be sufficiently exhibited, thereby causing difficulty in producing the aimed pigment having an excellent dispersibility. On the other hand, when the coating amount of the squaric acid is more than 10% by weight, no further effect of increasing dispersibility of the pigment may not be expected because the effect is already saturated.
The coating amount of the polyol having an anthraquinone skeleton, on surfaces of the core particles is preferably 0.01 to 10% by weight (calculated as C), more preferably 0.02 to 5% by weight based on the total weight of the pigment. When the coating amount of the polyol having an anthraquinone skeleton is less than 0.01% by weight, the effect of fixing the upper coat comprising alkylene glycol thereon in the next step may not be sufficiently exhibited, thereby causing difficulty in producing the aimed pigment having an excellent dispersibility. On the other hand, when the coating amount of the polyol is more than 10% by weight, no further effect of increasing dispersibility of the pigment may not be expected because the effect is already saturated.
Further, in the case where the lower coat comprises both squaric acid and polyol having an anthraquinone skeleton, the total coating amount of the squaric acid and the polyol having an anthraquinone skeleton on the surfaces of the core particles is preferably 0.01 to 10% by weight (calculated as C), more preferably 0.02 to 5% by weight based on the total weight of the pigment.
The coating amount of the alkylene glycol on the lower coat is preferably 0.01 to 10% by weight (calculated as C), more preferably 0.02 to 5% by weight based on the total weight of the pigment. When the coating amount of the alkylene glycol is less than 0.01% by weight, it may become difficult to produce the aimed pigment having an excellent dispersibility. On the other hand, when the coating amount of the alkylene glycol is more than 10% by weight, no further effect of increasing dispersibility of the pigment may not be expected because the effect is already saturated.
The average particle diameter, shape and BET specific surface area of the pigment according to the present invention may be almost the same as those of the above-mentioned various known pigment particles used as the core particles.
The pigment according to the present invention is useful for not only an organic solvent-type paint but also a water-based paint. Especially, when the pigment is used in the water-based paint, there can be obtained a water-based paint having excellent coating properties.
As for the dispersibility of the pigment obtained by sequentially applying squaric acid as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on surfaces of core particles according to the present invention when used in a water-based paint, (i) in the case where red iron oxide particles are used as the core particles, the gloss of a coating film obtained by applying the paint on a substrate is not less than 82% when the dispersion time is 45 minutes and not less than 87% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (ii) In the case where yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iii) In the case where black iron oxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iv) In the case where brown iron oxide particles are used as the core particles, the gloss of a coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. The above-mentioned absolute value of reduction percentage of the gloss is measured by the method of the evaluation of the dispersion stability in the Examples.
As for the dispersibility of the pigment obtained by sequentially applying squaric acid as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in a water-based paint, in the case where pigment particles other than iron oxide particles and yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 75% when the dispersion time is 45 minutes and not less than 80% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
Alternatively, as for the dispersibility of the pigment obtained by sequentially applying squaric acid as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in an organic solvent-type paint, (i) in the case where red iron oxide particles are used as the core particles, the gloss of a coating film obtained by applying the paint on a substrate is not less than 82% when the dispersion time is 45 minutes and not less than 87% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (ii) In the case where yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iii) In the case where black iron oxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iv) In the case where brown iron oxide particles are used as the core particles, the gloss of a coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
As for the dispersibility of the pigment obtained by sequentially applying squaric acid as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in an organic solvent-type paint, in the case where pigment particles other than iron oxide particles and yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 75% when the dispersion time is 45 minutes and not less than 80% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
As for the dispersibility of the pigment obtained by sequentially applying polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in a water-based paint, (i) in the case where red iron oxide particles are used as the core particles, the gloss of a coating film obtained by applying the paint on a substrate is not less than 82% when the dispersion time is 45 minutes and not less than 87% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (ii) In the case where yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iii) In the case where black iron oxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iv) In the case where brown iron oxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
As for the dispersibility of the pigment obtained by sequentially applying polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in a water-based paint, in the case where pigment particles other than iron oxide particles and yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 75% when the dispersion time is 45 minutes and not less than 80% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
Alternatively, as for the dispersibility of the pigment obtained by sequentially applying polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in an organic solvent-type paint, (i) in the case where red iron oxide particles are used as the core particles, the gloss of a coating film obtained by applying the paint on a substrate is not less than 82% when the dispersion time is 45 minutes and not less than 87% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (ii) In the case where yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iii) In the case where black iron oxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%. (iv) In the case where brown iron oxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
As for the dispersibility of the pigment obtained by sequentially applying polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in an organic solvent-type paint, in the case where pigment particles other than iron oxide particles and yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 75% when the dispersion time is 45 minutes and not less than 80% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 10%.
As for the dispersibility of the pigment obtained by sequentially applying both squaric acid and polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in a water-based paint, (i) in the case where red iron oxide particles are used as the core particles, the gloss of a coating film obtained by applying the paint on a substrate is not less than 85% when the dispersion time is 45 minutes and not less than 90% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 6%. (ii) In the case where yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 83% when the dispersion time is 45 minutes and not less than 88% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (iii) In the case where black iron oxide particles are used as the core particles, the gloss of the coating film is not less than 83% when the dispersion time is 45 minutes and not less than 88% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (iv) In the case where brown iron oxide particles are used as the core particles, the gloss of the coating film is not less than 83% when the dispersion time is 45 minutes and not less than 88% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%.
As for the dispersibility of the pigment obtained by sequentially applying both squaric acid and polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on surfaces of core particles according to the present invention when used in a water-based paint, in the case where pigment particles other than iron oxide particles and yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%.
Alternatively, as for the dispersibility of the pigment obtained by sequentially applying both squaric acid and polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in an organic solvent-type paint, (i) in the case where red iron oxide particles are used as the core particles, the gloss of a coating film obtained by applying the paint on a substrate is not less than 85% when the dispersion time is 45 minutes and not less than 90% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 6%. (ii) In the case where yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 83% when the dispersion time is 45 minutes and not less than 88% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (iii) In the case where black iron oxide particles are used as the core particles, the gloss of the coating film is not less than 83% when the dispersion time is 45 minutes and not less than 88% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%. (iv) In the case where brown iron oxide particles are used as the core particles, the gloss of the coating film is not less than 83% when the dispersion time is 45 minutes and not less than 88% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%.
As for the dispersibility of the pigment obtained by sequentially applying both squaric acid and polyol having an anthraquinone skeleton represented by the general formula (I) as a lower coat and alkylene glycol represented by the general formula (II) as an upper coat on the surfaces of core particles according to the present invention when used in an organic solvent-type paint, in the case where pigment particles other than iron oxide particles and yellow iron oxide hydroxide particles are used as the core particles, the gloss of the coating film is not less than 80% when the dispersion time is 45 minutes and not less than 85% when the dispersion time is 90 minutes, with the absolute value of reduction percentage of the gloss being not more than 8%.
Next, the process for producing the pigment according to the present invention is described.
The core particles to be treated according to the present invention may be selected from the above-mentioned various known pigment particles.
The squaric acid used in the present invention is not particularly restricted. For example, commercially available 3,4-dihydroxy-3-cyclobutene-1,2-dione (produced by TOKYO KASEI KOGYO CO., LTD.) can be used as the squaric acid.
When the surfaces of the pigment particles as core particles are coated with squaric acid, the pigment particles to be treated and squaric acid are mixed together in water or alcohol as a dispersing solvent, and then the mixture is sufficiently stirred to apply the squaric acid on the surfaces of the pigment particles, followed by filtering and drying, thereby obtaining a pigment composed of the pigment particles coated with squaric acid. When the pigment particles to be treated and squaric acid are mixed together, the order of addition of these coating components into water or alcohol is optional, namely any one of these coating components may be added in advance of the other, or both can be added simultaneously.
The squaric acid used in the present invention is usually maintained in a solid state at ordinary temperature. Upon coating, the squaric acid may be directly added, or may be added in the form of a solution prepared by previously dissolving it in water or alcohol. Preferably, squaric acid is added in the form of a solution.
In the case where the squaric acid is added in the form of a solution, the concentration thereof is usually 0.1 to 50 g/liter, preferably 0.5 to 10 g/liter.
The amount of the squaric acid added is 0.025 to 30.0% by weight, preferably 0.05 to 25.0% by weight based on the weight of the pigment particles to be treated. When the amount of squaric acid added is less than 0.025% by weight, the effect of fixing the upper coat comprising alkylene glycol on the lower coat comprising squaric acid in the next step becomes insufficient, thereby causing difficulty in producing the aimed pigment having an excellent dispersibility. On the other hand, when the amount of the squaric acid added is more than 30.0% by weight, no further effect cannot be expected because the effect is already saturated.
In the present invention, as the polyol having an anthraquinone skeleton, there may be used those polyols containing anthraquinone as a main skeleton and having 2 to 4 hydroxyl groups in total, which are represented by the general formula: ##STR5## wherein m is an integer of 0 to 4, n is an integer of 0 to 4 and m+n is an integer of 2 to 4,
Specific examples of the polyols having an anthraquinone skeleton may include alizarin (1,2-dihydroxyanthraquinone) represented by the formula: ##STR6## quinizarin (1,4-dihydroxyanthraquinone) represented by the formula: ##STR7## chrysazin (1,8-dihydroxyanthraquinone) represented by the formula: ##STR8## or the like.
When the surfaces of the pigment particles as core particles are coated with polyol having an anthraquinone skeleton represented by the general formula (I), the pigment particles to be treated and the polyol having an anthraquinone skeleton are mixed together in alcohol as a dispersing solvent and then the resultant mixture is sufficiently stirred, followed by filtering and drying, thereby obtaining pigment particles coated with polyol having an anthraquinone skeleton. Since the polyol having an anthraquinone skeleton is usually maintained in a solid state at ordinary temperature, it is preferred that the polyol having an anthraquinone skeleton be used in the form of a solution upon coating by previously dissolving it in alcohol such as ethanol.
The concentration of the solution containing the polyol having an anthraquinone skeleton, is usually 0.1 to 50 g/liter, preferably 0.5 to 10 g/liter.
The amount of the polyol having an anthraquinone skeleton added is 0.015 to 20.0% by weight, preferably 0.03 to 10.0% by weight based on the weight of the core pigment particles to be treated. When the amount of the polyol having an anthraquinone skeleton added is less than 0.015% by weight, the effect of fixing the upper coat comprising alkylene glycol on the lower coat comprising the polyol having an anthraquinone skeleton in the next step may become insufficient, thereby causing difficulty in producing the aimed pigment having an excellent dispersibility. On the other hand, when the amount of the polyol having an anthraquinone skeleton added is more than 20.0% by weight, no further effect of increasing the dispersibility may not be expected because the effect is already saturated.
Meanwhile, in the case where the core pigment particles are to be coated with both squaric acid and polyol having an anthraquinone skeleton represented by the general formula (I), the total amount of the squaric acid added and the polyol having an anthraquinone skeleton added, is preferably 0.015 to 30.0% by weight, more preferably 0.03 to 15% by weight based on the weight of the core pigment particles.
As the alkylene glycol used in the present invention, there may be exemplified those represented by the general formula of C.sub.n H.sub.2n (OH).sub.2, wherein n (carbon number) is an integer of 2 to 10.
Specific examples of the alkylene glycols may include ethylene glycol, propylene glycol, trimethylene glycol, butane diol, pentane diol, hexane diol, pinacol, heptane diol, octane diol, nonane diol, decane diol or the like. The carbon number of the alkylene glycol is preferably 2 to 7, more preferably 2 to 6. When the carbon number n is more than 11, the alkylene glycol may exhibit a high melting point, whereby there may arise such disadvantage that the treatment for uniformly coating the surfaces of the pigment particles with alkylene glycol must be conducted at a relatively high temperature.
The amount of the alkylene glycol added is usually 0.015 to 30% by weight, preferably 0.03 to 15% by weight based on the weight of the core pigment particles. When the amount of the alkylene glycol added is less than 0.015% by weight, the resultant coated particles may not exhibit a sufficient charging property, thereby causing difficulty in producing the aimed pigment having an excellent dispersibility. On the other hand, when the amount of the alkylene glycol added is more than 30% by weight, no further effect of increasing the dispersibility may not be obtained because the effect is already saturated.
The pigment particles coated with squaric acid, polyol having an anthraquinone skeleton or both thereof, can be further coated with the alkylene glycol only by mixing the coated pigment particles from the first coating step and the alkylene glycol together in a mixer under a dry mixing method.
Meanwhile, when the coated pigment particles from the first coating step is mixed with the alkylene glycol, it is preferred that the coated pigment particles is previously heated to a temperature of not less than 40.degree. C., preferably not less than 60.degree. C., more preferably 80 to 120.degree. C. to adjust the water content thereof to not more than 0.5% by weight. When the water content in the coated pigment particles from the first coating step is too large, the coated pigment particles are forced to agglomerate with each other by the action of water crosslinked between the particles. Once such an agglomeration is caused, it may become difficult to uniformly coat individual pigment particles with alkylene glycol.
As the mixers used in the present invention for mixing the coated pigment particles from the first coating step and alkylene glycol with each other, there may be exemplified any mixers commonly used for this purpose, such as high-speed agitation-type mixer, Henschel mixer, speed mixer, ball cutter, power mixer, hybrid mixer or the like. Among them, Henschel mixer is preferably used to form a uniform coat comprising alkylene glycol on the surface of the coated pigment particles.
The temperature upon mixing or stirring is preferably not less than 40.degree. C., more preferably not less than 60.degree. C., and the upper limit thereof is not more than the boiling point of alkylene glycol used. It is preferred that the mixing is performed at a temperature of not less than 40.degree. C. in order to reduce the viscosity of alkylene glycol used and form a uniform coat comprising alkylene glycol on the surfaces of the coated pigment particles.
The mixing or stirring time is usually at least 5 minutes, preferably not less than 10 minutes.
Next, the water-based paint according to the present invention is described.
The water-based paint according to the present invention is a paint prepared by using water as a main solvent, and therefore, includes both water-soluble paints and water-dispersion paints.
The water-dispersion paints may further include emulsion-type paints and colloidal dispersion-type paints.
The water-based paint according to the present invention comprises a paint base material and a pigment dispersed therein. The amount of the pigment dispersed may be in the range of 10 to 90 parts by weight based on 100 parts by weight of the paint base material. In view of handling of the obtained paint, the amount of the pigment dispersed is preferably in the range of 20 to 60 parts by weight, more preferably 30 to 50 parts by weight based on 100 parts by weight of the paint base material. When the shear rate D of the water-based paint is 1.92 sec.sup.-1, the apparent viscosity of the water-based paint according to the present invention is preferably 100 to 3,000 cP, more preferably 300 to 2,000 cP.
The absolute value of zeta potential of the water-based paint according to the present invention is preferably not less than 10 mV, more preferably not less than 20 mV.
The storage stability of the water-based paint according to the present invention is preferably not less than 70%, more preferably not less than 75%.
Meanwhile, the pigment according to the present invention can also be suitably applied to organic solvent-type paints. In this case, the organic solvent-type paint is composed of a paint base material and a pigment dispersed therein. The amount of the pigment dispersed may be in the range of 10 to 90 parts by weight based on 100 parts by weight of the basic constituting material. In view of handling of the obtained organic solvent-type paint, the amount of the pigment dispersed is preferably 20 to 60 parts by weight, more preferably 30 to 50 parts by weight based on 100 parts by weight of the paint base material.
The paint base material may contain water, a resin, a solvent, and if required, extender pigment particles, a drying accelerator, a surfactant, a curing promoter, auxiliaries or the like.
The amount of the solvent used in the paint according to the present invention is preferably 50 to 5,000 parts by weight, more preferably 100 to 2,000 parts by weight based on 100 parts by weight of the resin. When the amount of the solvent is less than 50 parts by weight based on 100 parts by weight of the resin, the vehicle viscosity of the paint may become too high so that it is difficult to perform homogeneous mixing and dispersion. On the other hand, when the amount of the solvent is more than 5,000 parts by weight, the solvent content in the paint may increase to such an extent that the dispersing shear force does not act on the particles during mixing and dispersion.
The resins for water-based paints usable in the present invention may include those commonly used for this purpose, such as water-soluble alkyd resins, water-soluble acrylic resins, water-soluble urethane resins, water-soluble epoxy resins, water-soluble melamine resins, acrylic emulsion resin, acrylic styrene emulsion resins, urethane emulsion resins, epoxy emulsion resins, vinyl acetate emulsion resins or the like.
As the resins for organic solvent-type paints, there can be used those commonly used for this purpose, such as acrylic resins, alkyd resins, polyester resins, polyurethane resins, epoxy resins, phenol resins, melamine resins, amino resins or the like.
Examples of the solvents for water-based paints used in the present invention may include those commonly used for this purpose, such as water, butyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether, methyl cellosolve acetate, butoxyethyl acetate, ethoxyethanol, hexoxyethanol, methyl ethyl ketone, phenyl glycol ether, ethanol, butyl alcohol, butoxyethanol, propanol, propoxypropanol or the like.
As the solvents for organic solvent-type paints, there can be exemplified those commonly used for this purpose, such as toluene, xylene, butyl acetate, methyl acetate, methyl isobutyl ketone, butyl cellosolve, ethyl cellosolve, butyl alcohol, aliphatic hydrocarbons or the like.
As the defoaming agents used in the present invention, there may be exemplified commercially available products such as NOPCO 8034, SN DEFOAMER 477, SN DEFOAMER 5013, SN DEFOAMER 247, SN DEFOAMER 382 (tradenames: produced by SANNOPCO CO., LTD.), ANTIFOAM 08, EMULGEN 903 (tradenames: produced by KAO CO., LTD.) or BYK-020 (tradename: produced by BYK CO., LTD.).
In the water-based paints, there may also be used film-forming assistants such as alcohols or glycol ethers.
The emulsion-type paints can be prepared by adding a pigment, an additive, water and if necessary, an organic solvent to an emulsion resin. As the additives, there may be exemplified dispersant, rust preventive, defoaming agent, film-forming agent or the like. As the film-forming agents, there may be used higher alcohols, glycols and hydrocarbons.
The colloidal dispersion-type paints may be composed of a colloidal dispersion resin, a pigment, an additive, a neutralizer, water, an organic solvent or the like.
As the additives for the colloidal dispersion-type paints, there may be exemplified dispersant, defoaming agent, rust preventive or the like, i.e., the same additives as those for the emulsion-type paints except film-forming agent.
The water-based paints may be composed of a water-soluble resin, a pigment, an additive, water, an organic solvents or the like. As the additives for the water-based paints, there may be exemplified dispersant, defoaming agent, neutralizer, rust preventive or the like.
In addition, if required, the water-based paint may further contain extender pigment, aggregate, neutralizer, film-forming assistant, pigment dispersant, pigment wetting agent, thickener (viscosity-imparting agent), antiseptic agent, mildew proofing agent, antifreezing agent, rust preventive, dryer or the like.
The water-based paint according to the present invention can be produced by dispersing the pigment according to the present invention and the above-mentioned paint base material in specific weight ratios in water by a commonly used mixer such as ball mill, roll mill, homomixer, shaker, attritor or sand grinder.
The pigment according to the present invention, which has a lower coat formed on surface of the core particles, comprising squaric acid and/or polyol having an anthraquinone skeleton represented by the general formula (I) and an upper coat comprising alkylene glycol represented by the general formula (II), can be applied to both of the water-based paint and the organic solvent-type paint, and can exhibit excellent dispersion facility, dispersion homogeneity and dispersion stability, irrespective of type of the paint used.
The reason why the pigment according to the present invention can be effectively applied to both the water-based paint and organic solvent-type paint, is considered by the present inventors as follows.
That is, in the organic solvent-type paint, a resin is absorbed on the surfaces of the pigment particles with a spread, so that when the pigment particles approach each other, a large repulsion force, i.e., so-called steric hindrance effect, is produced by the absorbed resin so as to hinder the approach of the pigment particles to each other, thereby allowing the pigment particles to stay stably in the paint.
In the water-based paints, however, as described above, the resin exists in the form of particles without spread on the surfaces of the pigment particles, the steric hindrance effect observed with respect to the pigment particles in the organic solvent-type paints is unlikely to be achieved, thereby causing difficulty in dispersing the pigment particles in the water-based paint.
It is known that, generally, the higher the absolute value of zeta potential of suspended particles in a paint, the more excellent the dispersibility of the suspended particles due to electrostatic repulsion.
However, in the case of the coated pigment particles according to the present invention which has a lower coat formed on surface of the core particles, comprising squaric acid and/or polyol having an anthraquinone skeleton represented by the general formula (I) and an upper coat comprising alkylene glycol represented by the general formula (II), the zeta potential in the water-based paint is about -20 to -100 mV, especially about -30 to -100 mV, as described in Examples hereinafter, and the absolute value thereof is high, so that in the water-based paint, the surface of the particles tend to be charged negatively, thereby producing a large electrostatic repulsion between the particles. Due to the large electrostatic repulsion, agglomerated particles tend to be released from each other, and allowed to be dispersed in a state approximating that of the primary particles, thereby enabling the pigment to be dispersed in the water-based paint with excellent dispersion facility and dispersion homogeneity.
After once dispersed in a state close to the primary particles, the coated pigment particles can be maintained in such a dispersed state for a long period of time by the electrostatic repulsion between the particles, thereby ensuring excellent dispersion stability of the particles.
With respect to the bonding condition between squaric acid and the core pigment particles, for example, in Japanese Patent Application Laid-open (KOKAI) No. 5-225552(1993), it is described that "It was confirmed that when the particles are treated with 3,4-dihydroxy-3-cyclobutene, water is produced by the treatment reaction. This indicates that the adsorption reaction between the treating agent and the surfaces of the ferromagnetic metal fine particles is accompanied with dehydration, and that the oxygen atom of hydroxyl group of the compound is directly bonded to the surfaces of the ferromagnetic metal fine particles (e.g., iron particles)."
In addition, since the pigment according to the present invention has the lower coat formed on the surfaces of the core particles, comprising squaric acid and/or polyol having an anthraquinone skeleton, the alkylene glycol upper coat can be firmly fixed on the particles due to the chemical bond between alkylene glycol and squaric acid and/or polyol having an anthraquinone skeleton.
Whereas, when only a single coat comprising squaric acid and/or polyol having an anthraquinone skeleton exists on the surfaces of the core particles, the absolute value of zeta potential is small as described in Comparative Examples 40 to 42 and 82 to 84 hereinafter, so that the pigment cannot be charged sufficiently and the dispersibility thereof becomes unsatisfactory.
Also, when only a single coat comprising alkylene glycol exists on the surfaces of the core particles, the alkylene glycol coat tends to be separated and peeled-off from the surfaces of the core particles as described in Comparative Examples 34 to 36 and 62 to 64 hereinafter, so that the pigment cannot be charged sufficiently and the dispersibility thereof becomes unsatisfactory.
Further, in the case where the order of application of the upper and lower coats is reversed, i.e., in the case where alkylene glycol is first applied onto the surfaces of the core particles to form a lower coat, the alkylene glycol lower coat is fallen-off together with an upper coat comprising squaric acid and/or polyol having an anthraquinone skeleton from the surfaces of the core particles as described in Comparative Examples 38 and 80 hereinafter, since the alkylene glycol has less bonding force to the surfaces of the core particles as described above. Thus, in such a case, the coats no longer exhibit their own functions, so that the pigment cannot be charged sufficiently and the dispersibility thereof becomes unsatisfactory.
As described in Examples hereinafter, in the case where squaric acid and polyol having an anthraquinone skeleton are used in combination to form a lower coat, the alkylene glycol upper coat is more stably fixed on the particles, so that the pigment can be more readily charged to a negative potential, and therefore, can show more excellent dispersion facility, dispersion homogeneity and dispersion stability.
Since the pigment according to the present invention shows excellent dispersion facility, dispersion homogeneity and dispersion stability in a paint, especially in a water-based paint, it is suitably used as pigment particles for paint.
Furthermore, the water-based paint according to the present invention can exhibit an excellent storage stability due to the fact that the pigment particles dispersed in a paint base material are excellent in dispersion facility, dispersion homogeneity and dispersion stability.

EXAMPLES
The present invention will now be described in more detail with reference to the following examples, but the present invention is not restricted to those examples and various modifications are possible within the scope of the invention.
(1) The average size (average diameter or average major axial diameter and the average minor axial diameter) of the particles are expressed by the average values of 350 particles measured in the photograph obtained by magnifying an electron micrograph (.times.30000) by 4 times in the vertical and horizontal directions, respectively. The aspect ratio is the ratio of the average major axial diameter and the average minor axial diameter.
(2) The coating amounts of squaric acid and polyol having an anthraquinone skeleton as a lower coat, and alkylene glycol as an upper coat were shown by the amount of carbon measured by using HORIBA METALLIC CARBON AND SULFUR ANALYZER EMIA-2200 (manufactured by HORIBA SEISAKUSHO CO., LTD.).
Incidentally, the coating amount of the alkylene glycol upper coat was shown by a calculated value obtained by subtracting the amount of carbon of the lower coat previously measured after the formation of the lower coat, from that of the upper coat measured after the formation of the upper coat.
(3) The viscosity of saint was determined by measuring a viscosity of a water-based paint prepared by mixing the obtained pigment particles with other paint components at specific weight ratios, at 25.degree. C. and at a shear rate D of 1.92 sec.sup.-1 by using E-type viscometer (cone plate-type viscometer) EMD-R (manufactured by TOKYO KEIKI CO., LTD.).
(4) The evaluations of dispersion facility, dispersion homogeneity and dispersion stability was shown in terms of gloss of a coating film as measured by a digital gloss meter UGV-5D (manufactured by SUGA SHIKENKI CO., LTD.) at an angle of incidence of 20.degree.. The higher the gloss, the more excellent the dispersibility.
The dispersion facility was shown in terms of gloss of the coating film formed by applying a paint obtained by blending the specific paint components at the specific ratios shown below and dispersing a mill base therein for 45 minutes, on a cold rolled steel plate (0.8 mm.times.70 mm.times.150 mm) (JIS G 3141) to a coating thickness of 150 .mu.m, followed by drying.
The dispersion homogeneity of the pigment was shown in terms of gloss of the coating film formed by applying a paint obtained by blending the specific paint components at the specific ratios shown below and dispersing a mill base therein for 90 minutes, on a cold rolled steel plate (0.8 mm.times.70 mm.times.150 mm) (JIS G 3141) to a coating thickness of 150 .mu.m, followed by drying.
As for the dispersion stability of the pigment, a paint prepared by blending the specific components at the specific ratios shown below, dispersing a mill base therein for 90 minutes, and then diluting the resultant dispersion by adding thereto, in the case of an organic solvent-type paint, a solvent in an amount of 40% based on the organic solvent-type paint, and in the case of a water-based paint, water in an amount of 40% based on the weight of the water-based paint, was applied on a cold rolled steel plate (0.8 mm.times.70 mm.times.150 mm) (JIS G 3141) to a coating thickness of 150 .mu.m, followed by drying to form a coat and its gloss was measured. The dispersion stability was shown by the absolute value of difference between glass of the coating film formed by applying a paint after dilution and that before dilution. The smaller the absolute value of the difference, the better the dispersion stability.
(5) The storage stability of a water-based saint was shown in terms of gloss of the coating film formed by applying a paint prepared by blending the specific components at the specific ratios shown below, dispersing a mill base therein for 90 minutes and allowing the preparation to stand for a day, on a cold rolled steel plate (0.8 mm.times.70 mm.times.150 mm) (JIS G 3141) to a coating thickness of 150 .mu.m, followed by drying.
(6) The zeta potential of the coated pigment particles in the water-based paint was determined by a zeta potentiometer Model-501 (manufactured by PEN-KEM INC.) using a suspension prepared by adding 0.5 g of a paint which had been obtained by blending the specific components at the specific ratios shown below and dispersing a mill base therein for 90 minutes, to 100 g of pure water, and dispersing the paint by an ultrasonic disperser C-10 (manufactured by CHO-ONPA KOGYO CO., LTD.) for one minute.
Example 1
Production of Pigment
30 g of squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione: produced by TOKYO KASEI KOGYO CO., LTD.) was added to 5 liter of pure water to prepare an aqueous squaric acid solution. The aqueous squaric acid solution was mixed with an additional amount of water to increase a total volume thereof to 25 liters, and stirred intimately. At this time, the concentration of squaric acid in the solution was 1.2 g/liter.
3.0 kg of granular red iron oxide particles (.alpha.-Fe.sub.2 O.sub.3) having an average particle diameter of 0.25 .mu.m were gradually added to the aqueous squaric acid solution, and then mixed together while stirring for 30 minutes by a homomixer, followed by filtering and drying, thereby obtaining granular red iron oxide particles (.alpha.-Fe.sub.2 O.sub.3) whose surfaces were coated with squaric acid.
The coating amount of squaric acid on the surfaces of the granular red iron oxide particles (.alpha.-Fe.sub.2 O.sub.3) was 0.41% by weight calculated as carbon.
2.5 kg of the granular red iron oxide particles (.alpha.-Fe.sub.2 O.sub.3) whose surfaces were coated with squaric acid, was charged into a 10-liter Henschel mixer previously heated to 60.degree. C., and mixed intimately by operating the mixer at 1,200 rpm for 10 minutes to remove water therefrom, thereby adjusting the water content of the coated granular red iron oxide particles to 0.19% by weight.
While the temperature of the Henschel mixer was maintained at 60.degree. C., 25 g of propylene glycol (produced by YONEYAMA YAKUHIN CO., LTD.) (corresponding to 1.0% by weight based on the weight of the coated granular red iron oxide particles) was gradually added to the squaric acid-coated granular red iron oxide particles at a rate of 2.5 g/min for 10 minutes. Successively, the obtained mixture was mixed for 20 minutes to further coat the squaric acid-coated granular red iron oxide particles with propylene glycol.
Next, while continuing the mixing by the Henschel mixer, the resultant mixture was cooled to room temperature to form a coat of propylene glycol on the surfaces of the granular iron oxide particles coated with squaric acid. The coating amount of propylene glycol on the squaric acid-coated granular red iron oxide particles was 0.45% by weight (calculated as carbon) based on the total weight of the pigment.
Example 2
Production of Water-Based Paint
Using 7.62 g of the pigment comprising the coated granular red iron oxide particles obtained in Example 1, respective raw materials for mill base shown below were mixed with each other in such amounts (part by weight) as shown below in 140-ml glass container. The obtained mixture was further mixed and dispersed together with 90 g of 3 mm.phi. glass beads in a paint shaker for 45 minutes to prepare a mill base.
Raw Materials for Mill base
Pigment (coated granular red iron iron oxide particles) 12.4 parts by weight
Water-soluble alkyd resin (tradename: S-118, produced by DAI-NIPPON INK KAGAKU KOGYO CO., LTD.) 9.0 parts by weight
Defoaming agent 0.1 part by weight
Water 4.8 parts by weight
Butyl cellosolve 4.1 parts by weight
Using the obtained mill base, respective raw materials for paint shown below were mixed with each other in such amounts (part by weight) as shown below, and further mixed and dispersed in a paint shaker for 15 minutes to obtain a water-based paint.
Raw Materials for Paint
Mill base obtained above 30.4 parts by weight
Water-soluble alkyd resin (tradename: S-118, produced by DAI-NIPPON INK KAGAKU KOGYO CO., LTD.) 46.2 parts by weight
Water-soluble melamine resin (tradename: S-695, produced by DAI-NIPPON INK KAGAKU KOGYO CO., LTD.) 12.6 part by weight
Defoaming agent (tradename: NOPCO 8034, produced by SUNNOPCO CO., LTD.) 0.1 part by weight
Water 9.1 parts by weight
Butyl cellosolve 1.6 parts by weight
The obtained water-based paint had a paint viscosity of 1,075 cP, and the gloss of a coating film formed by using the paint was 86% when the dispersion time of the mill base was 45 minutes, and the gross thereof was 90% when the dispersion time of the mill base was 90 minutes, with the average value of reduction percentage of the gloss being 6%.
Further, the water-based paint showed a storage stability of 81% and a zeta potential of -35.7 mV.
Example 3
Production of Organic Solvent-type Paint
Using 10 g of the pigment comprising the coated red iron oxide particles obtained in Example 1, respective raw materials for mill base shown below were mixed with each other in such amounts (part by weight) as shown below in 140-ml glass container. The obtained mixture was further mixed and dispersed together with 90 g of 3 mm.phi. glass beads in a paint shaker for 45 minutes or for 90 minutes to prepare a mill base.
Raw Materials for Mill base
Pigment (coated granular red iron oxide particles) 12.2 parts by weight
Aminoalkyd resin (tradename: AMILAC NO. 1026, produced by KANSAI PAINT CO., LTD.) 19.5 parts by weight
Thinner 7.3 parts by weight
Using the thus obtained mill base, respective raw materials for paint shown below were mixed with each other in such amounts (part by weight) as shown below, and further mixed and dispersed in a paint shaker for 15 minutes to obtain an organic solvent-type paint.
Raw Materials for Paint
Mill base obtained above 39.0 parts by weight
Aminoalkyd resin (tradename:
AMILAC NO. 1026, produced by KANSAI PAINT CO., LTD.) 61.0 parts by weight
The obtained organic solvent-type paint had a paint viscosity of 870 cP, and the gloss of a coating film formed by using the paint was 88% when the dispersion time of the mill base was 45 minutes and the gross thereof was 92% when the dispersion time of the mill base was 90 minutes, with the average value of reduction percentage of the gloss being 6%.
Examples 4 to 15 and Comparative Examples 1 to 14
Production of Pigment Using Iron Oxide-Based Particles
The same procedure as defined in Example 1 was conducted except that kind and amount of iron oxide-based particles or iron oxide hydroxide particles to be treated, coating amount of squaric acid, kind and coating amount of polyol having an anthraquinone skeleton, kind and coating amount of alkylene glycol, and mixing temperatures therefor were varied as shown in Tables 1 and 2, thereby producing coated iron oxide-based particles or coated iron oxide hydroxide particles as pigments. Various conditions used for the production of the pigments are shown in Tables 1 and 2.
TABLE 1______________________________________ Coating treatment Particles to be treated Major axial diameterExamples Kind Shape (.mu.m)______________________________________Example 4 Red iron oxide Granular 0.21Example 5 Red iron oxide Granular 0.21Example 6 Red iron oxide Granular 0.15Example 7 Yellow iron oxide Acicular 0.40 hydroxideExample 8 Black iron oxide Granular 0.32Example 9 Brown iron oxide Granular 0.28Example 10 Red iron oxide Granular 0.21Example 11 Red iron oxide Granular 0.21Example 12 Red iron oxide Granular 0.15Example 13 Yellow iron oxide Acicular 0.40 hydroxideExample 14 Black iron oxide Granular 0.32Example 15 Brown iron oxide Granular 0.28______________________________________ Coating treatment Particles to be treated Minor axial BET specific diameter surface areaExamples (.mu.m) (m.sup.2 /g) Amount (kg)______________________________________Example 4 -- 8.3 2.5Example 5 -- 8.3 2.5Example 6 -- 12.1 2.0Example 7 0.08 17.6 2.0Example 8 -- 4.9 2.5Example 9 -- 6.1 2.5Example 10 -- 8.3 2.5Example 11 -- 8.3 2.5Example 12 -- 12.1 2.0Example 13 0.08 17.6 2.0Example 14 -- 4.9 2.5Example 15 -- 6.1 2.5______________________________________Coating treatment Coating of lower layerHeat treatment Polyol havingbefore coating Amount of anthraquinone Residual squaric skeleton water acid Amount Temp. content added addedExamples (.degree. C.) (%) (wt %) Kind (wt %)______________________________________Example 4 60 0.19 1.5 -- --Example 5 40 0.34 1.0 -- --Example 6 80 0.10 3.0 -- --Example 7 80 0.16 5.0 -- --Example 8 60 0.26 -- Alizarin 1.0Example 9 40 0.15 -- Alizarin 1.0Example 10 60 0.13 -- Alizarin 0.5Example 11 40 0.21 -- Alizarin 3.0Example 12 60 0.18 0.5 Alizarin 1.5Example 13 50 0.46 1.5 Alizarin 0.5Example 14 60 0.20 1.0 Alizarin 1.0Example 15 80 0.11 2.0 Chrysazin 2.0______________________________________Coating treatmentCoating of upper layerAlkylene glycol Mixing Amount added temperatureExamples Kind (wt %) (.degree. C.)______________________________________Example 4 Propylene glycol 1.5 60Example 5 Propylene glycol 2.0 60Example 6 Propylene glycol 5.0 80Example 7 Propylene glycol 0.5 80Example 8 Propylene glycol 1.5 60Example 9 1,5-pentane diol 2.0 40Example 10 1,5-pentane diol 0.5 80Example 11 Propylene glycol 0.2 60Example 12 Propylene glycol 1.5 65Example 13 1,4-butane diol 3.0 40Example 14 1,4-butane diol 1.8 65Example 15 Propylene glycol 2.5 80______________________________________
TABLE 2______________________________________ Coating treatment Particles to be treated Major axialComparative diameterExamples Kind Shape (.mu.m)______________________________________Comparative Red iron oxide Granular 0.21Example 1Comparative Red iron oxide Granular 0.15Example 2Comparative Yellow iron oxide Acicular 0.40Example 3 hydroxideComparative Black iron oxide Granular 0.32Example 4Comparative Brown iron oxide Granular 0.28Example 5Comparative Red iron oxide Granular 0.21Example 6Comparative Red iron oxide Granular 0.21Example 7Comparative Red iron oxide Granular 0.21Example 8Comparative Red iron oxide Granular 0.21Example 9Comparative Red iron oxide Granular 0.21Example 10Comparative Red iron oxide Granular 0.21Example 11Comparative Red iron oxide Granular 0.21Example 12Comparative Red iron oxide Granular 0.21Example 13Comparative Red iron oxide Granular 0.21Example 14______________________________________ Coating treatment Particles to be treated BET specificComparative Minor axial surface areaExamples diameter (.mu.m) (m.sup.2 /g) Amount (kg)______________________________________Comparative -- 8.3 --Example 1Comparative -- 12.1 --Example 2Comparative 0.08 17.6 --Example 3Comparative -- 4.9 --Example 4Comparative -- 6.1 --Example 5Comparative -- 8.3 2.5Example 6Comparative -- 8.3 2.5Example 7Comparative -- 8.3 2.5Example 8Comparative -- 8.3 2.5Example 9Comparative -- 8.3 2.5Example 10Comparative -- 8.3 2.5Example 11Comparative -- 8.3 2.5Example 12Comparative -- 8.3 2.5Example 13Comparative -- 8.3 2.5Example 14______________________________________Coating treatment Coating of lower layerHeat treatment Polyol havingbefore coating anthraquinone Residual Amount of skeleton water squaric AmountComparative Temp. content acid added addedExamples (.degree. C.) (%) (wt %) Kind (wt %)______________________________________Comparative -- -- -- -- --Example 1Comparative -- -- -- -- --Example 2Comparative -- -- -- -- --Example 3Comparative -- -- -- -- --Example 4Comparative -- -- -- -- --Example 5Comparative 40 0.34 -- -- --Example 6Comparative 60 0.18 -- -- --Example 7Comparative 10 0.76 -- -- --Example 8 cooledComparative 40 0.30 0.005 -- --Example 9Comparative 60 0.19 0.1* -- --Example 10Comparative 60 0.18 -- Alizarin 0.1Example 11Comparative -- -- 1.0 -- --Example 12Comparative -- -- -- Alizarin 1.0Example 13Comparative -- -- 0.5 Alizarin 0.5Example 14______________________________________ Coating treatment Coating of upper layer Alkylene glycol MixingComparative Amount added temperatureExamples Kind (wt %) (.degree. C.)______________________________________Comparative -- -- --Example 1Comparative -- -- --Example 2Comparative -- -- --Example 3Comparative -- -- --Example 4Comparative -- -- --Example 5Comparative Propylene glycol 0.1 80Example 6Comparative 1,5-pentane diol 0.1 80Example 7Comparative 1,4-butane diol 1.0 40Example 8Comparative Propylene glycol 0.1 60Example 9Comparative 1,5-pentane diol* 0.2 60Example 10Comparative 1,4-butane diol 0.002 60Example 11Comparative -- -- --Example 12Comparative -- -- --Example 13Comparative -- -- --Example 14______________________________________ (Note): *: The order of coating was reversed, that is, after 1,5pentane diol was applied, the coating of squaric acid was conducted.
Examples 16 to 27 and Comparative Examples 15 to 28
Production of Organic solvent-type Paint Using Iron Oxide-Based Particles
The same procedure as defined in Example 3 was conducted except that kind and amount of iron oxide-based particles or iron oxide hydroxide particles to be treated were varied as shown in Tables 3 and 4, thereby producing an organic solvent-type paint. Various conditions used for the production of the organic solvent-type paint and properties of the obtained organic solvent-type paints are shown in Tables 3 and 4.
TABLE 3__________________________________________________________________________Coated pigment particles Coating amount of polyol having an Coating amount of anthraquinone Coating amount of Kind squaric acid skeleton alkylene glycol (Example (calculated as C) (calculated as C) (calculated as C)Examples No.) (wt %) (wt %) (wt %)__________________________________________________________________________Example 16 Example 4 0.61 -- 0.67Example 17 Example 5 0.40 -- 0.89Example 18 Example 6 1.21 -- 2.21Example 19 Example 7 2.00 -- 0.22Example 20 Example 8 -- 0.68 0.68Example 21 Example 9 -- 0.68 1.10Example 22 Example 10 -- 0.34 0.28Example 23 Example 11 -- 2.01 0.09Example 24 Example 12 0.20 1.00 0.70Example 25 Example 13 0.61 0.33 1.50Example 26 Example 14 0.41 0.67 0.90Example 27 Example 15 0.82 1.33 1.13__________________________________________________________________________ Properties of organic solvent-type paint Dispersion stability Gloss (absolute value Dispersion time Dispersion time of reduction Paint viscosity of mill base: 45 of mill base: 90 percentage ofExamples (cP) minutes (%) minutes (%) gloss) (%)__________________________________________________________________________Example 16 879 88 91 6Example 17 973 87 91 5Example 18 1024 89 93 7Example 19 2560 84 87 8Example 20 568 83 87 6Example 21 768 83 88 6Example 22 923 90 93 1Example 23 870 90 93 3Example 24 768 88 91 2Example 25 2688 91 94 5Example 26 768 90 92 4Example 27 691 93 95 3__________________________________________________________________________
TABLE 4__________________________________________________________________________Coated pigment particles Coating amount of polyol having an Coating amount of anthraquinone Coating amount of squaric acid skeleton alkylene glycolComparative Kind (calculated as C) (calculated as C) (calculated as C)Examples (Example No.) (wt %) (wt %) (wt %)__________________________________________________________________________Comparative Comparative -- -- --Example 15 Example 1Comparative Comparative -- -- --Example 16 Example 2Comparative Comparative -- -- --Example 17 Example 3Comparative Comparative -- -- --Example 18 Example 4Comparative Comparative -- -- --Example 19 Example 5Comparative Comparative -- -- 0.04Example 20 Example 6Comparative Comparative -- -- 0.05Example 21 Example 7Comparative Comparative -- -- 0.51Example 22 Example 8Comparative Comparative 0.002 -- 0.04Example 23 Example 9Comparative Comparative 0.04 -- 0.11Example 24 Example 10Comparative Comparative -- 0.07 0.001Example 25 Example 11Comparative Comparative 0.41 -- --Exampie 26 Example 12Comparative Comparative -- 0.68 --Example 27 Example 13Comparative Comparative 0.20 0.33 --Example 28 Example 14__________________________________________________________________________ Properties of organic solvent-type paint Dispersion stability Gloss (absolute value Dispersion time Dispersion time of reduction Paint viscosity of mill base: 45 of mill base: 90 percentage ofExamples (cP) minutes (%) minutes (%) gloss) (%)__________________________________________________________________________Comparative 1024 78 83 11Example 15Comparative 1050 76 83 12Example 16Comparative 2253 70 77 12Example 17Comparative 896 72 79 14Example 18Comparative 870 75 81 13Example 19Comparative 998 77 84 13Example 20Comparative 1024 78 86 11Example 21Comparative 1050 79 84 10Example 22Comparative 1100 79 86 10Example 23Comparative 973 76 85 12Example 24Comparative 923 81 86 10Example 25Comparative 896 83 85 10Example 26Comparative 998 84 86 11Example 27Comparative 896 84 86 9Example 28__________________________________________________________________________
Examples 28 to 39 and Comparative Examples 29 to 42
Production of Water-Based Paint Using Iron Oxide-Based Particles
The same procedure as defined in Example 2 was conducted except that kind of coated iron oxide-based particles or coated iron oxide hydroxide particles used were varied as shown in Tables 5 and 6, thereby producing a water-based paint. Various conditions used for the production of the water-based paint and properties of the obtained water-based paints are shown in Tables 5 and 6.
TABLE 5__________________________________________________________________________Coated pigment particles Coating amount of polyol having an Coating amount of anthraquinone Coating amount of Kind squaric acid skeleton alkylene glycol (Example (calculated as C) (calculated as C) (calculated as C)Examples No.) (wt %) (wt %) (wt %)__________________________________________________________________________Example 28 Example 4 0.61 -- 0.67Example 29 Example 5 0.41 -- 0.89Example 30 Example 6 1.21 -- 2.21Example 31 Example 7 2.00 -- 0.22Example 32 Example 8 -- 0.68 0.68Example 33 Example 9 -- 0.68 1.10Example 34 Example 10 -- 0.34 0.28Example 35 Example 11 -- 2.01 0.09Example 36 Example 12 0.20 1.00 0.70Example 37 Example 13 0.61 0.33 1.50Example 38 Example 14 0.41 0.67 0.90Example 39 Example 15 0.82 1.33 1.13__________________________________________________________________________ Properties of water-based paint Gloss Paint viscosity Dispersion time of mill Dispersion time of millExamples (cP) base: 45 minutes (%) base: 90 minutes (%)__________________________________________________________________________Example 28 1280 87 91Example 29 1126 86 90Example 30 1331 86 87Example 31 2304 84 86Example 32 896 80 85Example 33 973 80 86Example 34 1024 88 91Example 35 1075 87 93Example 36 972 91 96Example 37 2048 88 91Example 38 896 86 94Example 39 844 86 95__________________________________________________________________________ Properties of water-based paint Dispersion stability (absolute value of reduction percentage ofExamples gloss) (%) Storage stability (%) Zeta potential (mV)__________________________________________________________________________Example 28 6 83 -37.6Example 29 7 80 -38.9Example 30 7 88 -41.3Example 31 10 86 -36.8Example 32 8 80 -41.5Example 33 6 86 -33.6Example 34 6 83 -42.3Example 35 7 91 -53.2Example 36 6 86 -41.9Example 37 6 88 -51.3Example 38 4 90 -48.7Example 39 5 88 -46.1__________________________________________________________________________
TABLE 6__________________________________________________________________________Coated pigment particles Coating amount of polyol having an Coating amount of anthraquinone Coating amount of Kind squaric acid skeleton alkylene glycolComparative (Example (calculated as C) (calculated as C) (calculated as C)Examples No.) (wt %) (wt %) (wt %)__________________________________________________________________________Comparative Comparative -- -- --Example 29 Example 1Comparative Comparative -- -- --Example 30 Example 2Comparative Comparative -- -- --Example 31 Example 3Comparative Comparative -- -- --Example 32 Example 4Comparative Comparative -- -- --Example 33 Example 5Comparative Comparative -- -- 0.04Example 34 Example 6Comparative Comparative -- -- 0.05Example 35 Example 7Comparative Comparative -- -- 0.51Example 36 Example 8Comparative Comparative 0.002 -- 0.04Example 37 Example 9Comparative Comparative 0.04 -- 0.11Example 38 Example 10Comparative Comparative -- 0.07 0.001Example 39 Example 11Comparative Comparative 0.41 -- --Example 40 Example 12Comparative Comparative -- 0.68 --Example 41 Example 13Comparative Comparative 0.20 0.33 --Example 42 Example 14__________________________________________________________________________ Properties of water-based paint GlossComparative Paint viscosity Dispersion time of mill Dispersion time of millExamples (cP) base: 45 minutes (%) base: 90 minutes (%)__________________________________________________________________________Comparative 1050 63 68Example 29Comparative 1100 62 66Example 30Comparative 2560 60 64Example 31Comparative 896 58 53Example 32Comparative 998 65 71Example 33Comparative 1100 68 73Example 34Comparative 998 71 76Example 35Comparative 1152 73 76Example 36Comparative 1024 70 75Example 37Comparative 879 72 74Example 38Comparative 768 69 75Example 39Comparative 1050 66 71Example 40Comparative 1152 71 76Example 41Comparative 1203 68 71Example 42__________________________________________________________________________ Properties of water-based paint Dispersion stability (absolute value of reduction percentage ofExamples gloss) (%) Storage stability (%) Zeta potential (mV)__________________________________________________________________________Comparative 15 62 -13.6Example 29Comparative 18 62 -16.5Example 30Comparative 12 59 -10.6Example 31Comparative 18 46 -11.3Example 32Comparative 20 42 -8.4Example 33Comparative 12 63 -18.6Example 34Comparative 13 62 -17.8Example 35Comparative 11 60 -21.6Example 36Comparative 11 59 -16.8Example 37Comparative 12 63 -19.8Example 38Comparative 13 65 -23.8Example 39Comparative 14 61 -19.7Example 40Comparative 11 58 -13.6Example 41Comparative 15 63 -11.8Example 42__________________________________________________________________________
Examples 40 to 51 and Comparative Examples 43 to 56
Production of Pigment Using Particles Other Than Iron Oxide-Based Particles
The same procedure as defined in Example 1 was conducted except that kind of particles to be treated, coating amount of squaric acid, kind and coating amount of polyol having an anthraquinone skeleton added, kind and coating amount of alkylene glycol added and mixing temperatures therefor were varied as shown in Tables 7 and 8, thereby producing coated pigment particles as pigments. Various conditions used for the production of the pigments are shown in Tables 7 and 8.
TABLE 7______________________________________ Coating treatment Particles to be treated Major axial diameterExamples Kind Shape (.mu.m)______________________________________Example 40 Titanium dioxide Granular 0.28Example 41 Titanium dioxide Granular 0.25Example 42 Chrome yellow Granular 0.36Example 43 Chrome yellow Granular 0.32Example 44 Chromium oxide Granular 0.30 greenExample 45 Chromium oxide Granular 0.30 greenExample 46 Titanium dioxide Granular 0.28Example 47 Titanium dioxide Granular 0.25Example 48 Chrome yellow Granular 0.36Example 49 Chrome yellow Granular 0.32Example 50 Chromium oxide Granular 0.30 greenExample 51 Chromium oxide Granular 0.31 green______________________________________ Coating treatment Particles to be treated BET specific Minor axial surface areaExamples diameter (.mu.m) (m.sup.2 /g) Amount (kg)______________________________________Example 40 -- 10.6 2.5Example 41 -- 16.8 2.5Example 42 -- 6.4 2.5Example 43 -- 9.8 2.5Example 44 -- 6.9 2.5Example 45 -- 6.9 2.5Example 46 -- 10.6 2.5Example 47 -- 16.8 2.5Example 48 -- 6.4 2.5Example 49 -- 9.8 2.5Example 50 -- 7.2 2.5Example 51 -- 6.9 2.5______________________________________Coating treatment Coating of lower layerHeat treatment Polyol havingbefore coating Amount of anthraquinone Residual squaric skeleton water acid Amount Temp. content added addedExamples (.degree. C.) (%) (wt %) Kind (wt %)______________________________________Example 40 60 0.18 2.0 -- --Example 41 80 0.11 0.5 -- --Example 42 70 0.16 3.0 -- --Example 43 60 0.17 5.0 -- --Example 44 80 0.09 -- Alizarin 1.0Example 45 65 0.10 -- Alizarin 0.5Example 46 80 0.10 -- Alizarin 3.0Example 47 60 0.11 -- Alizarin 1.0Example 48 60 0.14 0.5 Alizarin 1.5Example 49 40 0.25 3.0 Alizarin 0.2Example 50 65 0.13 1.5 Alizarin 1.0Example 51 75 0.09 0.2 Chrysazin 1.5______________________________________ Coating treatment Coating of upper layer Alkylene glycol Mixing Amount added temperatureExamples Kind (wt %) (.degree. C.)______________________________________Example 40 Propylene glycol 2.0 60Example 41 Propylene glycol 3.0 65Example 42 Propylene glycol 0.5 80Example 43 Propylene glycol 1.5 75Example 44 Propylene glycol 2.0 60Example 45 1,5-pentane diol 5.0 60Example 46 1,5-pentane diol 0.1 70Example 47 Propylene glycol 1.5 40Example 48 Propylene glycol 2.0 55Example 49 1,4-butane diol 1.0 70Example 50 1,4-butane diol 2.5 80Example 51 1,5-pentane diol 1.5 60______________________________________
TABLE 8______________________________________ Coating treatment Particles to be treated Major axialComparative diameterExamples Kind Shape (.mu.m)______________________________________Comparative Titanium dioxide Granular 0.28Example 43Comparative Titanium dioxide Granular 0.25Example 44Comparative Chrome yellow Granular 0.36Example 45Comparative Chrome yellow Granular 0.32Example 46Comparative Chromium oxide Granular 0.30Example 47 greenComparative Titanium dioxide Granular 0.28Example 48Comparative Titanium dioxide Granular 0.28Example 49Comparative Titanium dioxide Granular 0.28Example 5QComparative Titanium dioxide Granular 0.28Example 51Comparative Titanium dioxide Granular 0.28Example 52Comparative Titanium dioxide Granular 0.28Example 53Comparative Titanium dioxide Granular 0.28Example 54Comparative Titanium dioxide Granular 0.28Example 55Comparative Titanium dioxide Granular 0.28Example 56______________________________________ Coating treatment Particles to be treated BET specificComparative Minor axial surface areaExamples diameter (.mu.m) (m.sup.2 /g) Amount (kg)______________________________________Comparative -- 10.6 --Example 43Comparative -- 16.8 --Example 44Comparative -- 6.4 --Example 45Comparative -- 9.8 --Example 46Comparative -- 6.9 --Example 47Comparative -- 10.6 2.5Example 48Comparative -- 10.6 2.5Example 49Comparative -- 10.6 2.5Example 50Comparative -- 10.6 2.5Example 51Comparative -- 10.6 2.5Example 52Comparative -- 10.6 2.5Example 53Comparative -- 10.6 2.5Example 54Comparative -- 10.6 2.5Example 55Comparative -- 10.6 2.5Example 56______________________________________Coating treatment Coating of lower layerHeat treatment Polyol havingbefore coating anthraquinone Residual Amount of skeleton water squaric AmountComparative Temp. content acid added addedExamples (.degree. C.) (%) (wt %) Kind (wt %)______________________________________Comparative -- -- -- -- --Example 43Comparative -- -- -- -- --Example 44Comparative -- -- -- -- --Example 45Comparative -- -- -- -- --Example 46Comparative -- -- -- -- --Example 47Comparative 40 0.40 -- -- --Example 48Comparative 60 0.19 -- -- --Example 49Comparative 15 1.01 -- -- --Example 50Comparative 60 0.16 0.002 -- --Example 51Comparative 60 0.17 0.2* -- --Example 52Comparatiye 40 0.32 -- Alizarin 0.1Example 53Comparative -- -- 1.5 -- --Example 54Comparative -- -- -- Alizarin 0.8Example 55Comparative -- -- 0.3 Alizarin 1.0Example 56______________________________________Coating treatmentCoating of upper layerAlkylene glycol MixingComparative Amount added temperatureExamples Kind (wt %) (.degree. C.)______________________________________Comparative -- -- --Example 43Comparative -- -- --Example 44Comparative -- -- --Example 45Comparative -- -- --Example 46Comparative -- -- --Example 47Comparative Propylene glycol 0.5 80Example 48Comparative 1,5-pentane diol 0.1 40Example 49Comparative 1,4-butane diol 0.2 80Example 50Comparative Propylene glycol 0.05 60Example 51Comparative 1,5-pentane diol* 0.3 60Example 52Comparative 1,4-butane diol 0.003 60Example 53ComparativeExample 54ComparativeExample 55ComparativeExample 56______________________________________ (Note) *: The coating order was reversed, that is, after 115pentane diol was applied, the coating of squaric acid was conducted.
Examples 52 to 63 and Comparative Examples 57 to 70
Production of Organic solvent-type Paint Using Pigment Particles Other Than Iron Oxide-Based Particles
The same procedure as defined in Example 3 was conducted except that kind of coated pigment particles used were varied as shown in Tables 9 and 10, thereby producing an organic solvent-type paint. Various conditions used for the production of the organic solvent-type paint and properties of the obtained organic solvent-type paints are shown in Tables 9 and 10.
TABLE 9__________________________________________________________________________Coated pigment particles Coating amount of polyol having an Coating amount of anthraquinone Coating amount of Kind squaric acid skeleton alkylene glycol (Example (calculated as C) (calculated as C) (calculated as C)Examples No.) (wt %) (wt %) (wt %)__________________________________________________________________________Example 52 Example 40 0.81 -- 0.90Example 53 Example 41 0.20 -- 1.31Example 54 Example 42 1.21 -- 0.23Example 55 Example 43 1.98 -- 0.70Example 56 Example 44 -- 0.68 0.90Example 57 Example 45 -- 0.34 2.68Example 58 Example 46 -- 2.03 0.05Example 59 Example 47 -- 0.68 0.66Example 60 Example 48 0.20 1.01 0.91Example 61 Example 49 1.20 0.13 0.49Example 62 Example 50 0.61 0.69 1.27Example 63 Example 51 0.08 1.02 0.82__________________________________________________________________________Properties of organic solvent-type paint Dispersion stability Gloss (absolute value Dispersion time Dispersion time of reduction Paint viscosity of mill base: 45 of mill base: 90 percentage ofExamples (cP) minutes (%) minutes (%) gloss) (%)__________________________________________________________________________Example 52 768 83 88 6Example 53 870 85 91 8Example 54 568 81 86 9Example 55 568 81 83 8Example 56 870 78 86 8Example 57 768 80 84 7Example 58 870 87 93 4Example 59 768 88 91 3Example 60 614 82 87 7Example 61 640 83 88 6Example 62 742 84 90 8Example 63 717 85 91 6__________________________________________________________________________
TABLE 10__________________________________________________________________________ Coated pigment particles Coating amount of polyol having Coating amount an anthraquinone Coating amount of squaric acid skeleton of alkyleneComparative Kind (calculated as C) (calculated as C) glycol (calculatedExamples (Example No.) (wt %) (wt %) as C) (wt %)__________________________________________________________________________Comparative Comparative -- -- --Example 57 Example 43Comparative Comparative -- -- --Example 58 Example 44Comparative Comparative -- -- --Example 59 Example 45Comparative Comparative -- -- --Example 60 Example 46Comparative Comparative -- -- --Example 61 Example 47Comparative Comparative -- -- 0.23Example 62 Example 48Comparative Comparative -- -- 0.05Example 63 Example 49Comparative Comparative -- -- 0.10Example 64 Example 50Comparative Comparative 0.0008 -- 0.02Example 65 Example 51Comparative Comparative 0.084 -- 0.10Example 66 Example 52Comparative Comparative -- 0.07 0.001Example 67 Example 53Comparative Comparative 0.60 -- --Example 68 Example 54Comparative Comparative -- 0.55 --Example 69 Example 55Comparative Comparative 0.12 0.68 --Example 70 Example 56__________________________________________________________________________Properties of organic solvent-type paint Dispersion stability Gloss (absolute value Dispersion time Dispersion time of reduction Paint viscosity of mill base: 45 of mill base: 90 percentage ofExamples (cP) minutes (%) minutes (%) gloss) (%)__________________________________________________________________________Comparative 870 71 74 16Example 57Comparative 896 71 75 18Example 58Comparative 768 73 78 13Example 59Comparative 717 71 76 12Example 60Comparative 1024 69 73 15Example 61Comparative 870 73 78 14Example 62Comparative 819 73 78 13Example 63Comparative 845 72 76 18Example 64Comparative 870 74 79 17Exampie 65Comparative 768 77 81 15Example 66Comparative 921 76 79 13Example 67Comparative 896 77 79 13Example 68Comparative 870 74 76 12Example 69Comparative 717 75 77 12Example 70__________________________________________________________________________
Examples 64 to 75 and Comparative Examples 71 to 84
Production of Water-Based Paint Using Pigment Particles Other Than Iron Oxide-Based Particles
The same procedure as defined in Example 2 was conducted except that kind of coated pigment particles used were varied as shown in Tables 11 and 12, thereby producing a water-based paint. Various conditions used for the production of the water-based paints and properties of the obtained water-based paints are shown in Tables 11 and 12.
TABLE 11__________________________________________________________________________Coated pigment particles Coating amount of polyol having an Coating amount of anthraquinone Coating amount of Kind squaric acid skeleton alkylene glycol (Example (calculated as C) (calculated as C) (calculated as C)Examples No.) (wt %) (wt %) (wt %)__________________________________________________________________________Example 64 Example 40 0.39 -- 0.46Example 65 Example 41 0.20 -- 1.31Example 66 Example 42 1.21 -- 0.23Example 67 Example 43 1.98 -- 0.70Example 68 Example 44 -- 0.68 0.90Example 69 Example 45 -- 0.34 2.68Example 70 Example 46 -- 2.03 0.05Example 71 Example 47 -- 0.68 0.66Example 72 Example 48 0.20 1.01 0.91Example 73 Example 49 1.20 0.13 0.49Example 74 Example 50 0.61 0.69 1.27Example 75 Example 51 0.08 1.02 0.82__________________________________________________________________________ Properties of water-based paint Gloss Paint viscosity Dispersion time of mill Dispersion time of millExamples (cP) base: 45 minutes (%) base: 90 minutes (%)__________________________________________________________________________Example 64 819 82 84Example 65 794 85 87Example 66 666 82 86Example 67 691 83 86Example 68 947 79 83Example 69 998 79 82Example 70 896 88 90Example 71 794 87 89Example 72 691 85 88Example 73 717 84 88Example 74 768 83 89Example 75 819 83 88__________________________________________________________________________Properties of water-based paint Dispersion stability (absolute value of reduction percentage ofExamples gloss) (%) Storage stability (%) Zeta potential (mV)__________________________________________________________________________Example 64 9 75 -41.6Example 65 8 81 -42.1Example 66 7 80 -31.6Example 67 7 80 -38.2Example 68 9 74 -45.6Example 69 8 77 -42.1Example 70 6 83 -51.3Example 71 5 85 -53.8Example 72 3 83 -48.9Example 73 4 82 -50.0Example 74 8 80 -49.3Example 75 6 83 -46.5__________________________________________________________________________
TABLE 12______________________________________ Coated pigment particles Coating amount Coating of polyol Coating amount of having an amount of squaric anthraquinone alkylene acid skeleton glycol Kind (calculated (calculated (calculatedComparative (Example as C) as C) as C)Examples No.) (wt %) (wt %) (wt %)______________________________________Comparative Comparative -- -- --Example 71 Example 43Comparative Comparative -- -- --Example 72 Example 44Comparative Comparative -- -- --Example 73 Example 45Comparative Comparative -- -- --Example 74 Example 46Comparative Comparative -- -- --Example 75 Example 47Comparative Comparative -- -- 0.23Example 76 Example 48Comparative Comparative -- -- 0.05Example 77 Example 49Comparative Comparative -- -- 0.10Example 78 Example 50Comparative Comparative 0.0008 -- 0.02Example 79 Example 51Comparative Comparative 0.084 -- 0.15Example 80 Example 52Comparative Comparative -- 0.07 0.001Example 81 Example 53Comparative Comparative 0.60 -- --Example 82 Example 54Comparative Comparative -- 0.55 --Example 83 Example 55Comparative Comparative 0.12 0.68 --Example 84 Example 56______________________________________Properties of water-based paintPaint GlossComparative viscosity Dispersion time of mill Dispersion time of millExamples (cP) base: 45 minutes (%) base: 90 minutes (%)______________________________________Comparative 1024 60 67Example 71Comparative 1100 63 71Example 72Comparative 998 61 69Example 73Comparative 923 62 71Example 74Comparative 768 59 66Example 75Comparative 973 65 72Example 76Comparative 998 68 75Example 77Comparative 896 66 76Example 78Comparative 1024 70 75Example 79Comparative 896 68 74Example 80Comparative 923 66 75Example 81Comparative 973 65 72Example 82Comparative 896 68 73Example 83Comparative 819 68 74Example 84______________________________________Properties of water-based paint Dispersion stability (absolute value of Storage ZetaComparative reduction percentage of stability potentialExamples gloss) (%) (%) (mV)______________________________________Comparative 18 66 -14.7Example 71Comparative 20 72 -15.6Example 72Comparative 15 68 -21.3Example 73Comparative 21 71 -18.8Example 74Comparative 23 56 -10.5Example 75Comparative 16 70 -19.6Example 76Comparative 18 65 -21.2Example 77Comparative 17 60 -23.8Example 78Comparative 15 62 -19.8Example 79Comparative 18 62 -18.6Example 80Comparative 17 63 -17.8Example 81Comparative 16 68 -25.3Example 82Comparative 14 70 -28.6Example 83Comparative 14 72 -27.9Example 84______________________________________

Number	Date	Country
4-92803	Mar 1992	JPX
5-225553	Sep 1993	JPX
5-225552	Sep 1993	JPX
8-120191	May 1996	JPX

Pigment, process for producing the same and paint using the same

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