Patent Application
20110250457
This invention relates to an in-mold coating composition and an in-mold-coated molded product, and more particularly to an in-mold-coated molded product obtained by a so-called in-mold coating molding method (which is also referred to as an IMC method or an in-mold coating method) in which a thermoplastic molding material or a thermosetting plastic molding material is molded in a mold by means of an injection molding method, an injection compression molding method, an injection press molding method, a compression molding method or a reaction injection molding method, and then an in-mold coating composition is injected between the surface of the obtained molded product and the surface of a mold cavity and cured in the mold to produce an integral molded product in which the in-mold coating composition adheres to the surface of the molded plastic product.
For the purpose of lengthening a life of product by improving a scratch resistance in the surface of a molded plastic product used for automobiles, construction machines, architectural materials or the like, or improving a weathering resistance, coating a molded product has been heretofore used widely. In this case, an electrostatic coating is generally used for improving a coating efficiency in top coating or reducing the emission of volatile organic compounds (VOC) to the atmosphere. However, the volume resistivity value of molded plastic product is usually 1010Ω/cm2 or more, and hence it is difficult to coating uniformly with a coating material even if the electrostatic coating method is used. Thus, when these molded products are subjected to the electrostatic coating, a spray coating with a conductive primer coating material is carried out for the purpose of forming a coating film having conductive properties. However, there is recently a strong interest about environmental issues, and the tendency to limit severely the emission of volatile organic compounds, what is called VOC, from paint factories to the atmosphere becomes stronger, and thus the development of an alternative technique to the conventional conductive primer is imperative.
Under such a situation, an in-mold coating molding method of injecting a coating material between the surface of a molded plastic product formed in a mold and the cavity surface of the mold, and thereafter curing the coating material in the mold to produce an integral molded product in which a coating film adheres to the surface of the molded plastic product attracts attention.
Since the in-mold coating molding method forms a coating film in a mold, the coating composition comprises no solvent and 100% coating film is formed in the mold. Thus, such a method emits no VOC into the atmosphere, and generates less waste, and has less impact on the environment. Also, the coating film is cured with a radical reaction by the heat of a mold, the heat of a thermoplastic resin in resin-plasticizing, and the heat of reaction of a thermosetting resin, and hence the expenditure of energy in forming of the coating film is lower as compared with reaction through the heat of a general drying furnace or ultraviolet irradiation. It is, therefore, said to be an excellent coating method.
The coating material used for in-mold coating molding is required to be cured for a short time with no solvents because of forming a coating film in a mold. Thus, the development is more difficult than that of general coating materials. In an already-developed conductive coating material used for an in-mold coating molding method, carbon black is used as a conductive material (for example, see Patent Documents 1 and 2).
Recently, design or color tone is emphasized, and thereby a coating material for in-mold coating molding having conductive properties and light color is required for the coating color of top coating material, and specifically for a light-colored metallic or pearl coating material. For such purpose, graphite is mainly used as a conductive material and titanium dioxide is contained as a coloring pigment for light color. The cured coating film takes on gray, but has insufficient whiteness degree and brightness if coated with a white color-based coating material having a poor hiding power and high brightness in top coating (for example, see Patent Document 3).
On the other hand, coating materials containing an organic solvent are generally used as a white conductive coating material (for example, see Patent Documents 4-8). However, they emits a large amount of VOC to the atmosphere in coating as mentioned above, and thus the development of coating materials of non-solvent type is demanded from the viewpoint of dealing with recent environment issues.
Patent Document 1: JP-A-S60-212467
Patent Document 2: JP-A-H04-226116
Patent Document 3: JP-A-H06-320681
Patent Document 4: JP-A-2004-75735
Patent Document 5: JP-A-2004-217872
Patent Document 6: JP-A-2004-262988
Patent Document 7: JP-A-2005-171024
Patent Document 8: JP-A-2006-232884
It is, therefore, an object of the invention to provide an in-mold coating composition having an excellent adhesion to SMC (sheet molding compound), BMC (bulk molding compound) or a thermosetting molding resin having dicyclopentadiene as a main component, or a thermoplastic molding resin such as ABS resin, polyamide resin, PPE resin, PC/PET, PC/PBT or PC/ABS alloy, or the like, and an in-mold-coated molded product formed by coating effectively with a white conductive coating film in a mold.
The inventors have made various studies in order to solve the above-mentioned problems and discovered that the above object can be achieved by the following constitutions, and as a result the invention has been accomplished.
That is to say, according to the invention, there is provided an in-mold coating composition characterized by comprising the following components:
(A) at least one selected from a urethane oligomer, an epoxy oligomer, a polyester oligomer and a polyether oligomer each having a (meth)acryloyl group, or an unsaturated polyester resin,
(B) a monomer capable of copolymerizing with the (A) component,
(C) a conductive particle formed by coating a surface of an inorganic particle with a conductive metal oxide particle, and
(D) an organic peroxide polymerization initiator, wherein
mass ratios of the (A) and (B) components satisfy (A)/(B)=20/80-80/20,
a mass ratio of the (C) component satisfies (C)/{(A)+(B)}=5/100-50/100, and
a mass ratio of the (D) component satisfies (D)/{(A)+(B)}=0.1/100-5/100.
According to the invention, there is also provided an in-mold-coated molded product characterized by being produced, with any one of an injection molding method, an injection compression molding method, an injection press molding method, a compression molding method or a reaction injection molding method as a molding method, by the following steps of:
clamping a mold composed of a fixed mold portion and a movable mold portion,
molding a resin in a cavity of the mold,
injecting an in-mold coating composition in the cavity,
curing the injected in-mold coating composition, and
removing a coated molded product after the curing of the in-mold coating composition, wherein the in-mold coating composition is the above-mentioned in-mold coating composition.
According to the invention, there can be provided an in-mold-coated molded product having a light-colored conductive coating film with an excellent adhesion by curing an in-mold coating composition on the surface of a molded product of a thermosetting molding resin or a thermoplastic molding resin in a mold, so that brighter color development of the top coating film can be achieved by the subsequent electrostatic top coating. Also, it is able to transfer the surface of a mold accurately by an in-mold coating molding method, and it is able to effectively-reduce a sink mark or a weld line occurring in a rib or a boss portion and accompanying the shrinkage of a molding resin which is unsolvable in a usual coating.
The in-mold-coated molded product according to the invention will be described concretely below.
The in-mold-coated molded product according to the invention consists of a molded product composed of a thermosetting molding resin or a thermoplastic molding resin and a coating film of an in-mold coating composition formed on the surface thereof.
As the thermosetting molding resin may be used molding materials known heretofore, and mentioned, for example, a fiber-reinforced plastic molding material, referred to as SMC or BMC, containing an unsaturated polyester resin, an epoxy acrylate resin or a phenol resin as a matrix, an RTM molding material containing an unsaturated polyester resin, an epoxy acrylate resin or an epoxy resin as a matrix, a RIM molding material using dicyclopentadiene, urethane or the like, and so on.
As the thermoplastic molding resin may be used various molding materials known heretofore, and mentioned, for example, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polyphenylene ether, ABS resin, or an alloy material thereof.
Such molding materials may include, for example, a reinforcing agent such as glass fiber, carbon fiber, calcium carbonate whisker or the like, an ultraviolet absorbing agent, an antioxidant, a release agent, or the like so as to satisfy characteristics depending on a use application.
Next, the in-mold coating material used in the invention will be described.
The in-mold coating material used in the invention comprises the following essential components:
(A) at least one selected from a urethane oligomer, an epoxy oligomer, a polyester oligomer and a polyether oligomer each having a (meth)acryloyl group, or an unsaturated polyester resin,
(B) a monomer capable of copolymerizing with the (A) component,
(C) a conductive particle formed by coating a surface of an inorganic particle with a conductive metal oxide particle, and
(D) an organic peroxide polymerization initiator, wherein
mass ratios of the (A) and (B) components satisfy (A)/(B)=20/80-80/20,
a mass ratio of the (C) component satisfies (C)/{(A)+(B)}=5/100-50/100, and
a mass ratio of the (D) component satisfies (D)/{(A)+(B)}=0.1/100-5/100. As necessary, the in-mold coating material used in the invention further comprises an optional component such as an inorganic particle, such as calcium carbonate, talc or the like, having an average particle diameter of not less than 0.1 μm but not more than 20 μm, a coloring pigment such as titanium dioxide or the like, a low-shrinking agent such as a diallyl phthalate oligomer, a saturated polyester resin or a polyvinyl acetate resin, a polymethyl methacrylate resin or the like, a release agent, an ultraviolet absorbing agent, an antioxidant, an anti-foaming agent, an antistatic agent, a polymerization inhibitor, a curing accelerator, or the like.
(a) As to (A) Component
The (A) component used in the in-mold coating composition used in the invention is at least one selected from a urethane oligomer, an epoxy oligomer, a polyester oligomer and a polyether oligomer each having a (meth)acryloyl group, or an unsaturated polyester resin.
(a-1) Oligomer having a (Meth)Acryloyl Group
The oligomer having the (meth)acryloyl group can include, for example, urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate and polyether (meth)acrylate.
The mass average molecular weights of these oligomers may vary depending on their types, and are generally suitable to be about 300-30,000, preferably 500-10,000. The oligomer having the (meth)acryloyl group is suitable to have a (meth)acryloyl group of at least 2-8, preferably 2-6 in one molecular.
(a-1-1) Urethane (Meth)Acrylate Oligomer
The urethane (meth)acrylate oligomer as a oligomer used in the invention can be produced with a usual method, for example, by mixing (1) an organic diisocyanate compound, (2) an organic polyol compound and (3) hydroxyalkyl (meth)acrylate at an abundance ratio such that NCO/OH ratio is, for example, 0.8-1.0, preferably 0.9-1.0. When the hydroxyl group is present in excess, or when hydroxyalkyl (meth)acrylate is used in large amounts, an oligomer having a lot of hydroxyl groups is obtained.
Concretely, (1) the organic diisocyanate compound is reacted with (2) the organic polyol compound or the like, for example, in the presence of a catalyst for urethane reaction such as dibutyltin laurate or the like to obtain an isocyanate-terminated polyurethane prepolymer. Then, the urethane (meth)acrylate oligomer can be produced by reacting (3) hydroxyalkyl (meth)acrylate until reaction with a free isocyanate group is mostly completed. With respect to ratio of (2) organic polyol compound and (3) hydroxyalkyl (meth)acrylate, the amount of the former is suitable, for example, to be about 0.1-0.5 moles based on 1 mole of the latter.
As (1) the organic diisocyanate compound used in the reaction can be used, for example, 1,2-diisocyanatoethane, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane, hexamethylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, bis(4-isocyanatocyclohexyl)methane, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatoethyl)cyclohexane, 1,3-bis(isocyanatomethyl)benzene, 1,3-bis(isocyanato-1-methylethyl)benzene or the like. These organic diisocyanate compounds can be used alone or as a mixture of two or more.
As (2) the organic polyol compound used in the reaction can preferably be mentioned organic diol compounds, for example, alkyldiol, polyether diol, polyester diol and so on. As a representative example of the alkyldiol can be mentioned, for example, ethylene glycol, 1,3-propanediol, propylene glycol, 2,3-butanediol, 1,4-butanediol, 2-ethylbutane-1,4-diol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,4-cyclohexanediol, 1,4-dimethylolcyclohexane, 4,8-dihydroxytricyclo[5.2.1.02,6]decane, 2,2-bis(4-hydroxycyclohexyl)propane and so on.
Polyether diol which is an organic diol compound can be synthesized, for example, by polymerizing aldehyde, alkylene oxide, glycol or the like according to a known method.
For example, polyether diol is obtained by an addition polymerization of formaldehyde, ethylene oxide, propylene oxide, tetramethylene oxide, epichlorohydrin or the like to alkyldiol under a suitable condition. As the polyester diol which is the organic diol compound can be used, for example, an esterification reaction product obtained by reacting a saturated or unsaturated dicarboxylic acid and/or an acid anhydride thereof with an excess amount of alkyldiol, and an esterification reaction product obtained by polymerizing hydroxycarboxylic acid and/or lactone as an intramolecular ester thereof and/or lactide as an intermolecular ester thereof to alkyldiol. These organic polyol compounds can be used alone or in a combination of two or more.
As (3) the hydroxyalkyl (meth)acrylate can be mentioned 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and so on. And, the urethane (meth)acrylate oligomer as an oligomer used in the invention can be also produced by reacting a compound having a (meth)acryloyl group and a hydroxyl group in one molecule with an organic diisocyanate compound at NCO/OH ratio of, for example, 0.9-1.0 and, for example in the presence of a catalyst for urethane reaction such as dibutyltin dilaurate or the like.
(a-1-2) Polyester (Meth)Acrylate Oligomer
Polyester (meth)acrylate which is an oligomer used in the invention can be produced, for example, by reacting polyester polyol having a hydroxyl group at its terminus with an unsaturated carboxylic acid. Such polyester polyol can be produced representatively by an esterification reaction of a saturated or unsaturated dicarboxylic acid or an acid anhydride thereof with an excess of alkylene diol. As a representative example of dicarboxylic acid used can be mentioned, for example, oxalic acid, succinic acid, adipic acid, phthalic acid, maleic acid and so on. As a representative example of alkylene diol used can be mentioned, for example, ethylene glycol, propylene glycol, butanediol, pentanediol and so on. As a representative example of the unsaturated carboxylic acid can be mentioned, for example, acrylic acid, methacrylic acid and so on.
(a-1-3) Epoxy (Meth)Acrylate Oligomer
Epoxy (meth)acrylate oligomer which is an oligomer used in the invention is produced, for example, by using an epoxy compound and the above-mentioned unsaturated carboxylic acid at a ratio such that, for example, 0.5-1.5 equivalents of carboxyl group is based on one equivalent of epoxy group, and conducting a usual ring-opening addition reaction of acid to epoxy group. As the epoxy compound used here can be preferably mentioned, for example, a bisphenol-A-type epoxy, a novolac-type phenolic epoxy and so on.
(a-1-4) Polyether (Meth)Acrylate Oligomer
Polyether (meth)acrylate which is an oligomer used in the invention can be produced, for example, by reacting polyether polyol such as polyethylene glycol, polypropylene glycol or the like with the above-mentioned unsaturated carboxylic acid.
(a-2) Unsaturated Polyester Resin
On the other hand, the unsaturated polyester resin used as the (A) component can be produced, for example, by reacting an organic polyol compound with an unsaturated carboxylic acid through a known method and, if necessary, further reacting with a saturated polycarboxylic acid. As a representative example of the organic polyol used can be mentioned, for example, ethylene glycol, propylene glycol, triethylene glycol, trimethylolpropane, glycerin, bisphenol-A and so on. As a representative example of the unsaturated polycarboxylic acid used can be mentioned, for example, (anhydrous) maleic acid, (anhydrous) fumaric acid, (anhydrous) itaconic acid and so on.
These (A) components may be used in a combination of the (meth)acryloyl group-containing oligomer and the unsaturated polyester resin.
(b) As to (B) Component
The (B) component used in the invention is an unsaturated monomer capable of copolymerizing with the (A) component.
As a representative example of such an unsaturated monomer can be mentioned, for example, styrene, a-methylstyrene, chlorostyrene, vinyl toluene, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ethylene glycol (meth)acrylate, cyclohexyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid amide, 2-acrylamide-2-methylpropane sulfonic acid, (meth)acrylic acid, β-(meth)acryloyloxyethyl hydrogen phthalate, β-(meth)acryloyloxyethyl hydrogen succinate, N-vinyl-2-pyrolidone, N-vinylcaprolactam, ethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, isobornyl (meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, triallyl isocyanurate and so on.
An aliphatic (meth)acrylate monomer like tripropylene glycol diacrylate (TPGDA) and 1,6-hexanediol diacrylate (1,6-HDDA), a (meth)acrylate monomer having an aliphatic structure like cyclohexyl methacrylate, trimethylolpropane triacrylate (TMPT) and so on are preferable.
With respect to the (B) component, the unsaturated monomers may be used alone or as a mixture thereof. When it comprises a monomer having one ethylenic double bond in one molecule and a monomer having two or more ethylenic double bond in one molecule, it is particularly preferable to raise the hardness of the formed coating film and thereby become difficult to scratch. It is preferable that the monomer having one ethylenic double bond in one molecule is styrene monomer and the content of styrene monomer to {(A)+(B)} components satisfies (styrene monomer)/{(A)+(B)}=0.2/100-5/100 in a mass ratio, because the pot life is lengthened significantly.
The mass ratios of the (A) and (B) components depend on types of compounds used as (A) and (B) components and so on, but they usually satisfy (A)/(B)=20/80-80/20, more preferably 33/67-67/33. When it is within this range, the curing properties is better and hence a robust cured coating film is obtained, and also the in-mold flow properties of the coating composition is better and hence a uniform coating film is obtained without inclusion of bubbles.
(c) As to (C) Component
As the (C) component used in the invention can be mentioned a conductive particle formed by coating the surface of an inorganic particle such as an acicular titanium dioxide, a potassium titanate whisker, mica or the like with a conductive metal oxide particle.
The inorganic particle coated with the conductive metal oxide particle in the (C) component is preferable to be at least one selected from titanium dioxide, zinc oxide, alumina, silica, alkali titanate, or mica.
The conductive metal oxide particle is preferable to be an acicular titanium dioxide, a potassium titanate whisker or a squamous mica, coated with any one of tin oxide, antimony-doped tin oxide or tin-doped indium oxide.
The antimony-doped tin oxide preferably contains 0.1-5% by mass of at least one of phosphorous, aluminum or molybdenum in an oxide form.
The conductive particle (C) is more preferable to have an aspect ratio of 3-200 because of developing the conductive properties of the cured coating film.
In particular, the mass ratio of the (C) component satisfies (C)/{(A)+(B)}=5/100-50/100, more preferably 7/100-30/100. The mass ratio of the (C) component is preferable to be not less than 5/100, because the cured coating film has sufficient conductive properties and hence an electrostatic top coating is carried out effectively. On the other hand, the mass ratio of the (C) component is preferable to be not more than 50/100, because the rising of viscosity can be suppressed within the limits and the in-mold flow properties are appropriate.
(d) As to (D) Component
The (D) component used in the invention is an organic peroxide polymerization initiator used for generating a free radical and polymerizing the (A) and (B) components. It is particularly preferable that the organic peroxide polymerization initiator contains an organic peroxide polymerization initiator having a one-minute half-life temperature of not less than 85° C. but less than 95° C. and an organic peroxide polymerization initiator having a one-minute half-life temperature of not less than 95° C. but less than 170° C.
The organic peroxide polymerization initiator having a one-minute half-life temperature of not less than 85° C. but less than 95° C. includes, for example, isobutyryl peroxide, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, di-isopropyl peroxydicarbonate and so on. Bis(4-t-butylcyclohexyl) peroxydicarbonate is particularly preferable. As a representative example of the organic peroxide polymerization initiator having a one-minute half-life temperature of not less than 95° C. but less than 170° C. are mentioned organic peroxides such as t-butyl peroxybenzoate, t-butyl peroxyisobutyrate, t-butyl peroxy2-ethylhexanoate, t-amyl peroxy2-ethylhexanoate, t-butyl peroxyisopropylcarbonate, lauroyl peroxide, benzoyl peroxide and so on. t-Butyl peroxybenzoate and t-amyl peroxy2-ethylhexanoate are particularly preferable.
The mass ratio of the organic peroxide polymerization initiator as the (D) component satisfies (D)/{(A)+(B)}=0.1/100-5/100, more preferably 0.5/100-3/100. When the compounding ratio of the organic peroxide polymerization initiator as the (D) component is less than 0.1/100, the reaction between (A) and (B) components is not successfully progressed and the failure of curing is caused not to obtain a normal coating film. While, when it exceeds 5/100, the pot life of the coating composition is shortened significantly.
(e) As to Other Components
The in-mold coating composition used in the invention can further comprise at least one inorganic particle, such as calcium carbonate, talc or the like, having an average particle diameter of not less than 0.1 μm but not more than 20 μm as needed. As such an inorganic particle may be preferably mentioned, for example, calcium carbonate, talc, barium sulfate, aluminum hydroxide, clay and so on. These inorganic particles are compounded for purposes of dispersing a shrinkage stress associated with the curing of coating film, improving an adhesion to a molded product, smoothing concave and convex in surface, or improving the appearance of the surface of a molded product.
The in-mold coating composition used in the invention can further comprise at least one coloring pigment as needed. The coloring pigment can be various coloring pigments conventionally-used for a usual plastics or a coating material.
For example, titanium dioxide, zinc oxide or the like can be used as a white pigment, and titanium yellow or the like can be used as a yellow pigment.
These light-colored coloring pigments are compounded for purposes of coloring the cured coating film of the in-mold coating composition in white color or light color, and developing an intended color even if coated with a light color-based top coating material having a poor hiding power.
In the invention, a release agent can be optionally used in combination in order to release a cured coating film smoothly from a mold. As the release agent can be mentioned, for example, stearic acid, hydroxystearic acid, stearate such as zinc stearate, aluminum stearate, magnesium stearate, calcium stearate or the like, soybean oil lecithin, silicone oil, fatty acid ester, fatty acid alcohol dibasic acid esters, and so on. The compounding amounts of these release agents are preferable to be, for example, 0.1-5 parts by mass, more preferably 0.2-2 parts by mass based on 100 parts by mass in total of {(A)+(B)} components. When it is within this range, the effect of releasing from a mold is preferably exercised.
In the invention, a modified resin can be compounded for purpose of improving an adhesion to various resins for substrate. As the modified resin used for this purpose can be mentioned, for example, chlorinated polyolefin, maleic acid-modified polyolefin, acrylic oligomer, polyvinyl acetate, polymethyl methacrylate, allyl ester oligomer and so on.
The in-mold coating composition used in the invention may be further compounded with various additives such as an antistatic agent, an antioxidant, an ultraviolet absorbing agent, a curing accelerator, a pigment dispersant, an anti-foaming agent, a plasticizer or the like as needed.
<Production Method of In-Mold-Coated Molded Product>
With respect to the production method of the in-mold-coated molded product according to the invention, the constitution of a molding machine for carrying out it, a molding tool and an injection equipment for a coating composition are described concretely below with reference to Drawings, but these concrete molding machine, molding tool and injection equipment for a coating composition are not intended as limitations of the invention.
In the equipment shown in
Also, the equipment shown in
In the molding, the clamping cylinder 5 is firstly operated to separate the upper mold 1 from the lower mold 2, and the glass fiber-reinforced plastic molding material is placed on the lower mold 2, and thereafter the clamping cylinder 5 is operated to approximate the upper mold 1 to the lower mold 2 and hence the molding material is formed into the shape of the cavity, and subjected to an application of a clamping pressure. The clamping pressure is usually 4-15 MPa. The molding temperature is determined optionally depending on a molding time, a kind of a molding material, and so on, but it is usually suitable to be 120-180° C. It is desirable that a mold is previously set to the above-mentioned temperature before a molding material is injected, and the temperature is held until a cured coating film to be hereinafter described is obtained.
Then, in the stage wherein the molded product in the cavity is cured to the extent that it can withstand the injection and flow pressures of the in-mold coating composition, the in-mold coating composition is injected from the injector 7 between the inner wall of the upper mold 1 and the molded product surface coated in the mold in the amount such that a cured coating film of a desired film thickness or preferably having a film thickness of 20-1,000 μm can be obtained, while holding the clamping pressure as it is, or after reducing the clamping pressure, or after separating the upper mold 1 from the surface of the molded product by a distance which is larger than the desired film thickness of the cured coating film but does not disengage the fitting of the upper mold 1 and the lower mold 2 or preferably by a distance of 0.2-5 mm.
After the injection of the in-mold coating composition, an injection port is closed by the shutoff pin 7A, and the in-mold coating composition is cured on the surface of the molded product in the cavity 6, if necessary, by moving the clamping cylinder 5 to conduct an clamping operation. The pressure is usually (re)applied to about 1-10 MPa so that the in-mold coating composition can uniformly coat the surface of the molded product, and then usually held for about 10-300 seconds until a cured coating film is formed. The cured coating film is thus formed on the surface of the molded product, and thereafter the clamping cylinder 5 is operated to separate the upper mold 1 from the lower mold 2 and the molded product having the cured coating film is removed from the mold.
Also, a means of injecting an in-mold coating composition in
In the molding, the clamping cylinder 15 is firstly operated to close the fixed mold member 13 and the movable mold member 14 and apply a clamping pressure. The clamping pressure is required to be able to withstand the injection pressure of the resin molding material. The injection pressure is usually a high pressure of 40-250 MPa in the portion of the nozzle 18. In this process, the supply pump is operated to supply a required amount of an in-mold coating composition to the measuring cylinder 23.
Then, the resin molding material in a molten or softened state is injected from the injection cylinder 17 into the cavity 16 through the nozzle 17 and the sprue 19. In the stage wherein the resin molding material is set in the mold to the extent that it can withstand the injection and flow pressures of the in-mold coating composition, the clamping pressure is reduced, or the movable mold portion 14 is moved back by a distance which is larger than the following desired film thickness of the cured coating film but does not disengage the fitting of the fixed mold member 13 and the movable mold member 14 or preferably by a distance of 0.2-5 mm. Then, the shutoff pin 22A is operated to open the injection port of the injector 22. Then, the plunger regulator 23A for injection of an in-mold coating composition of the measuring cylinder 23 is operated to inject the in-mold coating composition in the cavity 16, i.e. between the inner wall of the fixed mold member 13 and the molded resin product surface coated in the mold, in the amount such that a cured coating film of a desired film thickness or preferably having a film thickness of 20-1,000 μm can be obtained.
After the injection of the in-mold coating composition, the injection port is closed again by the shutoff pin 22A and, if necessary, the clamping cylinder 15 is moved to conduct an clamping operation, and the in-mold coating composition is pushed out to coat the surface of the molded product in the mold, and the in-mold coating composition is cured on the surface of the molded product in the cavity 16. Then, the clamping cylinder 15 is operated to separate the movable mold member 14 from the fixed mold member 13 and the molded product having the cured coating film is removed from the mold.
The molding tool members 26 (fixed type) and 27 (movable type) are fixed on a fixed platen and a movable platen of a clamping equipment, respectively. The movable platen is constituted to move back and forth by a clamping cylinder. The fixed platen, movable platen and clamping cylinder of the clamping equipment are not shown in
On the other hand, the embodiment in
In the molding, the clamping cylinder is firstly operated to close the mold (molding tool members 26 and 27) and apply a clamping pressure. The clamping pressure is usually 0.5-1 MPa. Then, the molding material containing dicyclopentadiene as a main component is injected from the mixing head 38 into the cavity 28. In this process, the supply pump 42 is operated to supply a required amount of an in-mold coating composition to the measuring cylinder 40. In the stage wherein the molding material is properly cured in the mold (to the extent that it can withstand the injection and flow pressures of the in-mold coating composition), the clamping pressure is held as it is, or reduced. Then, the injection port of the injector 39 is opened by movement of the shutoff pin 39A. Then, the plunger regulator 40A for injection of an in-mold coating composition of the measuring cylinder 40 is operated to fill the cavity 28, i.e. a space between the inner wall of the mold member 26 and the molded product surface, with the in-mold coating composition.
After the shutoff pin 39A is closed again, the in-mold coating composition is cured in the mold, if necessary, by moving the clamping cylinder to conduct a clamping operation. Then, the clamping cylinder is operated to separate both tool members 26 and 27 and the coated molded product is removed from the mold.
The invention will be described in more detail on the basis of the following Examples and Comparative Examples, but they are not intended as limitations of the invention.
<Synthesis of Urethane Oligomer>
A urethane oligomer can be produced by polymerizing according to various known methods. The synthesis example is as follows: dibutyltin dilaurate is charged into the amount of (A) component shown in Table 1, in which the amount of dibtutyltin dilaurate charged is 0.02 parts by mass based on 100 parts by mass in total of (A)-(C) components. Then, the amount of (B) component shown in Table 1 is added dropwise thereto with holding at 40° C. and reacted for a sufficient time, and thereafter a solution dissolving hydroquinone, in which the amount of hydroquinone dissolved is 0.1 parts by mass based on 100 parts by mass in total of (A)-(C) components, is added dropwise to (C) component shown in Table 1, and further stirred with heating at 75° C. for a sufficient time. Thus, urethane oligomers UAC-1-UAC-3 are obtained.
<Synthesis of Epoxy Oligomer>
1,000 parts by mass of an epoxy compound (trade name: EPIKOTE 828 (made by Yuka Shell Epoxy Corporation)), 490 parts by mass of methacrylic acid, 3 parts by mass of triethylamine and 0.01 parts by mass of hydroquinone are charged into a reactor, and reacted at 125° C. for 3 hours to obtain an epoxy oligomer EAC-1.
<Production of Conductive Particle (C)>
A conductive particle (C) can be produced according to various known methods.
Production of Conductive Particle EC-1
100 g of a rutile-type titanium dioxide powder (trade name: R-310, made by Sakai Chemical Industry CO., Ltd.) (97% or more of TiO2, and average primary particle diameter of 0.20 μm) is dispersed in 0.3 liters of pure water, to which 16 g of trichloroacetic aicd and 19 g of sodium trichloroacetate are added as a pH buffer agent.
An acidic aqueous solution of hydrochloric acid containing 17 g of stannic chloride and 2.5 g of antimony (III) chloride and an aqueous solution of sodium hydroxide (75 g/liter) are simultaneously added over 30 minutes while holding at 90° C., and hence the coating with the coprecipitated hydroxide of tin oxide and antimony oxide is carried out. Washing with water, filtering and drying are carried out, and thereafter sintering at 550° C. for 1 hour is carried out to obtain 110 g of a white powder (coating amount of 10% by mass), which has a whiteness degree of 83 and a volume resistivity of 4Ω·cm.
Production of Conductive Particle EC-2
100 g of a squamous fluorine mica powder (trade name: MK-100, made by Coop Chemical Co., Ltd.) (whiteness degree of 95, average particle diameter of 2 μm, and aspect ratio of 20-30) is dispersed in 0.3 liters of pure water, and held at 90° C., and added with an acidic aqueous solution of hydrochloric acid containing 3.5 g of stannic chloride, and thereafter an aqueous solution of sodium hydroxide (75 g/liter) is gradually added dropwise thereto over 10 minutes so as to be pH of 2-4, and hence hydrolyzing is carried out to form a coating film of tin hydrate on the powder.
Then, the solution is held at 90° C., to which an acidic aqueous solution of hydrochloric acid containing 14 g of stannic chloride and 5 g of antimony (III) chloride and an aqueous solution of sodium hydroxide (75 g/liter) are simultaneously added dropwise over 30 minutes so as to be pH of 2-4, and hence the powder having the coating film of tin hydrate is coated with the coprecipitated hydrate of tin and antimony. The resulting powder is filtered, washed with water and dried, and thereafter sintered at 550° C. for 1 hour to obtain 111 g of a white powder (coating amount of 11% by mass), which has a whiteness degree of 83 and a volume resistivity of 370Ω·cm.
Production of Conductive Particle EC-3
100 g of an acicular powder of rutile-type titanium dioxide (trade name: FTL-100, made by Ishihara Sangyo Co., Ltd.) (fiber length of 1.68 μm, and fiber diameter of 0.13 μm) is dispersed in 0.3 liters of pure water, to which 16 g of trichloroacetic aicd and 19 g of sodium trichloroacetate are added as a pH buffer agent.
An acidic aqueous solution of hydrochloric acid containing 17 g of stannic chloride and 2.5 g of antimony (III) chloride and an aqueous solution of sodium hydroxide (75 g/liter) are simultaneously added over 30 minutes while holding at 90° C., and hence the coating with the coprecipitated hydroxide of tin oxide and antimony oxide is carried out. Washing with water, filtering and drying are carried out, and thereafter sintering at 550° C. for 1 hour is carried out to obtain 110 g of a white powder (coating amount of 10% by mass), which has a whiteness degree of 88 and a volume resistivity of 6Ω·cm.
Production of Conductive Particle EC-4
100 g of a rutile-type titanium dioxide powder (trade name: R-310, made by Sakai Chemical Industry CO., Ltd.) (97% or more of TiO2, and average primary particle diameter of 0.20 μm) is dispersed in 0.3 liters of pure water, to which an acidic aqueous solution of hydrochloric acid containing 34 g of stannic chloride and 5 g of antimony trichloride and 50 milliliters of an aqueous solution of sodium hydroxide (500 g/liter) containing 0.7 g of sodium hexametaphosphate are simultaneously added dropwise over 30 minutes while holding at 90° C., whereby the coating with the coprecipitated hydroxide of tin oxide and antimony oxide containing phosphorus is carried out. Washing with water, filtering and drying are carried out, and thereafter sintering at 600° C. for 1 hour is carried out to obtain 121 g of a white powder (coating amount of 20% by mass, containing 1% by mass of phosphorus), which has a whiteness degree of 87 and a volume resistivity of 7Ω·cm.
Production of Conductive Particle EC-5
A white powder is produced in the same manner as in the conductive particle EC-3 except that an aqueous solution of sodium hydroxide containing 0.3 g of sodium aluminate is used. There is obtained 120 g of the white powder (coating amount of 20% by mass, containing 0.8% by mass of aluminum), which has a whiteness degree of 86 and a volume resistivity of 2Ω·cm.
A mold having a cavity for obtaining a molded resin product having a product shape of 800 mm in length, 300 mm in width, 50 mm in height and 3 mm in board thickness is used to conduct an in-mold coating to a molded product according to the embodiment shown in
With respect to the resulting molded product, the appearance of the coating film, the surface resistance value, the L* value based on L*a*b* display system prescribed in JIS Z 8729 and the adhesion of the coating film to a substrate are measured. The results are shown in Table 4.
Further, the resulting molded product is subjected to an electrostatic coating under the condition shown in Table 2. The coat appearance after the top coating is evaluated. DELICON #1500 white (made by Dai Nippon Toryo Co., Ltd.) is used as a top coating material.
[Appearance of Coating Film]
The gloss, flow streak, uniformity and so on of the coating film are visually confirmed, and the appearance is evaluated according to the followings:
Good . . . Uniform gloss, no flow streak, and uniform appearance.
Average . . . A little unevenness of gloss and flow streak.
Bad . . . Severe unevenness of gloss and flow streak, and ununiform appearance.
[L*Value]
L* value is measured on the basis of L*a*b* display system prescribed in JIS Z 8729.
[Surface Resistance Value]
The surface resistance value of the coating film is measured by using a measuring apparatus of Hiresta-UP MCP-HT450 type (made by Mitsubishi Chemical Corporation), after it is left in a room at 23±2° C. and 50±5% RH for 24 hours.
[Adhesion of Coating Film to Substrate]
The initial coat adhesion test is carried out according to JIS K 5600-5-6: Adhesion (cross-cut method). The adhesion of coating film is rated on the following 6-point scale of 0 to 5 based on the classification of test results described in JIS K 5600-5-6.
<6-Point Scale>
0 . . . The cut edge is fully smooth, and peelings are not present in any squares of the lattice.
1 . . . Small peelings of the coating film are present in the cut cross-point. The percentage of the affected portions in the cross-cut portions does not certainly exceed 5%.
2 . . . The coating film peels along the cut edge and/or in the cut cross-point. The percentage of the affected portions in the cross-cut portions certainly exceeds 5%, but it does not exceed 15%.
3 . . . The coating film forms large peelings partially or fully along the cut edge, and/or different portions in squares peel partially or fully. The percentage of the affected portions in the cross-cut portions certainly exceeds 15%, but it does not exceed 35%.
4 . . . The coating film forms large peelings partially or fully along the cut edge, and/or several squares peel partially or fully. The percentage of the affected portions in the cross-cut portions certainly exceeds 35%, but it does not exceed 65%.
5 . . . The degree of peelings exceeds the Classification 4.
[Coat Appearance after Top Coating]
Good . . . Invisible substrate, uniform gloss, and uniform appearance.
Bad . . . Visible substrate, uneven gloss, and ununiform appearance.
A mold having a cavity for obtaining a molded resin product having a box shape of 300 mm in length, 200 mm in width, 30 mm in height and 2.5 mm in board thickness is used to conduct an in-mold coating to a molded product according to the embodiment shown in
With respect to the resulting molded product, the appearance of the coating film, the surface resistance value, the L* value based on L*a*b* display system prescribed in JIS Z 8729 and the adhesion of the coating film to a substrate are measured in the same manner as in the above Examples. The results are shown in Table 6.
Further, the resulting molded product is subjected to an electrostatic coating under the same condition as described above. The coat appearance after the top coating is evaluated. In this case, PLANITTO#3600PA white (made by Dai Nippon Toryo Co., Ltd.) is used as a top coating material.
A mold having a cavity for obtaining a molded resin product having a box shape of 300 mm in length, 200 mm in width, 30 mm in height and 2.5 mm in board thickness is used to conduct an in-mold coating to a molded product according to the embodiment shown in
Then, the movable mold is spaced about 1 mm apart, and thereafter each coating composition shown in Table 7 of 13 cm3 is injected between the surface of the mold and the surface of the molded product over about 0.5 seconds. After the completion of injection, the clamping pressure is raised to 200 KN over 1 second and held for 60 seconds, whereby the in-mold coating composition is cured.
With respect to the resulting molded product, the appearance of the coating film, the surface resistance value, the L* value based on L*a*b* display system prescribed in JIS Z 8729 and the adhesion of the coating film to a substrate are measured in the same manner as in the above Examples. The results are shown in Table 8.
Further, the resulting molded product is subjected to an electrostatic coating under the same condition as described above. The coat appearance after the top coating is evaluated. In this case, PLANITTO #3600PA white (made by Dai Nippon Toryo Co., Ltd.) is used as a top coating material.
A mold having a cavity for obtaining a molded resin product using dicyclopentadiene as a main raw material and having a box shape of 400 mm in length, 400 mm in width and 30 mm in height is used to conduct an in-mold coating to a molded product according to the embodiment shown in
Then, each in-mold coating composition shown in Table 9 of 32 cm3 is injected between the surface of the mold and the surface of the molded product over about 1 second, while holding the clamping pressure. After the completion of injection, it is held for 200 seconds, whereby the in-mold coating composition is cured.
With respect to the resulting molded product, the appearance of the coating film, the surface resistance value, the L* value based on L*a*b* display system prescribed in JIS Z 8729 and the adhesion of the coating film to a substrate are measured in the same manner as in the above Examples. The results are shown in Table 10.
Further, the resulting molded product is subjected to an electrostatic coating under the same condition as described above. The coat appearance after the top coating is evaluated. In this case, PLANITTO#3600PA white (made by Dai Nippon Toryo Co., Ltd.) is used as a top coating material.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-314713 | Dec 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/070709 | 12/10/2009 | WO | 00 | 6/8/2011 |
