Polypropylene resin composition having an improved compatibility with paint-coatings and a paint-coated article thereof

FIELD OF THE INVENTION
The present invention relates to a polypropylene resin composition having an improved compatibility with paint-coatings, and to a paint-coated article thereof. It further relates to a process for producing a paint-coated article of polypropylene composition which is useful and suited especially for automotive exterior parts such as bumpers.
BACKGROUND OF THE INVENTION
Polypropylene compositions have been known to be difficult to print, bind and paint due to their nonpolarity. Therefore, there have been proposed improved methods for providing stable paint-coatings on the molded articles of polypropylene compositions. For example, so-called primers or under-coatings are usually applied as a medium layer between the polypropylene compositions and the paints to improve their compatibility. This method is, however, still unsatisfactory from the industrial point of view because a primer itself is expensive, an additional step required to apply a primer increases the costs of the final products, and a primer poses an environmental problem associated with its waste treatment.
Furthermore, the application of a primer is usually preceded by cleaning with vapors of halogenated hydrocarbons such as 1,1,1-trichloroethane. But, the use of 1,1,1-trichloroethane is now being banned in consideration of the ozone layer depletion and the protection of the global environment.
The surface treatments of molded articles of polypropylene compositions are another means to increase the binding strength of paints, prints or adhesives to them. For example, sandblasting, chromic acid treatment, flame treatment, corona discharge treatment, plasma treatment, surface activation with functional groups, and photo-induced surface grafting are applied before applying paints to the articles. However, none of them is satisfactory from the standpoint of performance and environmental problems.
Under the circumstances, the present inventors conducted research, which led to the finding that the compatibility and binding property of polypropylene compositions are greatly improved when crystalline polypropylene and an ethylene-propylene copolymer rubber are blended a with hydroxyl group-containing propylene oligomer. More specifically, it has been found that a polypropylene resin composition which comprises crystalline polypropylene, an ethylene-propylene copolymer rubber, a hydroxyl group-containing propylene oligomer, and optionally an inorganic filler has an advantageous and unique property in that it can easily and stably be paint-coated without pre-cleaning with vapor of 1,1,1-trichloroethane and a primer, but simply treating it with water or non-hologenated solvents such as alcohols, aromatic hydrocarbons or Keton-solvents before applying paints.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a polypropylene composition which comprises:
(A) 10-95 parts by weight of a crystalline polypropylene,
(B) 5-90 parts by weight of an ethylene-propylene copolymer rubber and
(C) 1-30 parts by weight, per 100 parts by weight of the mixture of said crystalline polypropylene and ethylene-propylene copolymer rubber, of a hydroxyl group-containing propylene oligomer, and
(D) optionally up to 40 parts by weight, per 100 parts by weight of the mixture of said crystalline polypropylene and ethylene-propylene copolymer rubber, of an inorganic filler.
The polypropylene composition may be molded into various automotive exterior parts and easily and stably paint-coated without pre-cleaning with vapors of 1,1,1-trichloroethane and laying a primer layer.
Another object is to provide a paint-coated molded article of said polypropylene composition which may be obtained by treating the surface of a molded article of said polypropylene composition with water or a solvent and applying paint thereon.
A further object is to provide a process for producing a paint-coated shaped article of said polypropylene composition such as automotive exterior parts which process comprises treating said molded article with water or a solvent and then applying paint thereon.
PREFERRED EMBODIMENTS OF THE INVENTION
The polypropylene composition of the present invention comprises:
(A) a crystalline polypropylene in an amount of 10-95 parts by weight,
(B) an ethylene-propylene copolymer rubber in an amount of 5-90 parts by weight and
(C) a hydroxyl group-containing propylene oligomer in an amount of 1-30 parts by weight per 100 parts by weight of the mixture of said crystalline polypropylene and ethylene-propylene copolymer rubber.
In addition to the above-mentioned components (A) to (C), the composition may optionally contain an inorganic filler in amount of not more than 40 parts by weight per 100 parts by weight of the mixture of said crystalline polypropylene and ethylene-propylene copolymer rubber.
Further, suitable amounts of conventional additives or auxiliaries may be added to the composition before or during the molding of the composition into shaped articles such as automotive parts.
Crystalline polypropylene
As the crystalline polypropylene, the following polymers are preferable and may be used alone or in combination:
(a) a homopolypropylene having a melt index of 10-100 g/10 min;
(b) a propylene-.alpha.-olefin random copolymer having a melt index of 10-100 g/10 min and containing 0.5-8 wt % of ethylene or C.sub.4-6 .alpha.-olefin;
(c) a propylene-ethylene block copolymer containing ethylene-propylene random copolymer units and crystalline polypropylene homopolymer units,
wherein the amount of said ethylene-propylene random copolymer units is 5 to 20% by weight relative to the total weight of the propylene-ethylene block copolymer, the ethylene content of the ethylene-propylene random copolymer units is 20 to 60% by weight, and the crystalline polypropylene homopolymer units have an intrinsic viscosity [.eta.] measured with tetralin solution at 135.degree. C. of 0.8 to 2.0 dl/g, a Q value, weight average molecular weight/number average molecular weight, measured by GPC of 3.0 to 5.0 and a content of xylene-soluble portion at 20.degree. C. of not more than 1.5% by weight.
As for the homopolypropylene (a), the one which has a melt index of 10-100 g/10 min is preferable because of the good appearance and impact strength of the resulting molded articles. Molded articles with inferior appearance (e.g., flow marks, gloss) are sometimes obtained when the melt index of the used homopolypropylene is less than 10 g/10 min, and when the melt index of used homopolypropylene is higher than 100 g/10 min, the resulting molded articles sometimes suffer from poor physical properties, especially low impact strength.
The propylene-.alpha.-olefin random copolymer (b) used in the invention includes a copolymer formed by copolymerization of propylene with and .alpha.-olefin such as ethylene, butene-1, hexene-1 and 4-methyl-pentene-1. The most desirable .alpha.-olefin is ethylene. Among these, those containing 0.5-8 wt % of .alpha.-olefin are preferable. With an .alpha.-olefin content higher than 8 wt %, the resulting molded article tends to be poor in physical properties, especially in heat resistance.
The preferred propylene-.alpha.-olefin random copolymer is the one which has a melt index of 10-100 g/10 min, for the same reason as in the case of the homopolypropylene.
As the propylene-ethylene block copolymer (c), preferred copolymers are those containing ethylene-propylene random copolymer units and crystalline polypropylene homopolymer units, wherein the amount of said ethylene-propylene random copolymer units is 5 to 20%, preferable 7 to 15% by weight relative to the total weight of the propylene-ethylene block copolymer, the ethylene content of the ethylene-propylene random copolymer units is 2.0 to 60%, preferably 20 to 50% by weight, and the crystalline polypropylene homopolymer units have an intrinsic viscosity [.eta.] measured with tetralin solution at 135.degree. C. of 0.8 to 20 dl/g, a Q value, weight average molecular weight/number average molecular weight, measured by GPC of 3.0 to 5.0 and a content of xylene-soluble portion at 20.degree. C. of not more than 1.5, preferably not more than 1.2% by weight.
The above-mentioned homopolypropylene (a), propylene-.alpha.-olefin random copolymer (b), and propylene-ethylene block copolymer (c) can be obtained by conventional methods, for example, by reacting the relevant monomers in the presence of a Ziegler-Natta catalyst, which is composed of titanium trichloride and alkyl aluminum compound.
As the crystalline polypropylene, a modified polypropylene or a mixture of a modified polypropylene and the above-mentioned crystalline polypropylene may also be used.
Said modified polypropylene can be obtained by grafting the above-mentioned crystalline polypropylene with an unsaturated carboxylic acid or the anhydride thereof in an amount of 0.05-20 wt %, preferably 0.1-10 wt % based on the weight of the crystalline polypropylene. Examples of the graft monomer to be used in said modification include acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride and itaconic anhydride. Of these, maleic anhydride is especially preferable.
The grafting of the polypropylene may be accomplished by known processes. For example, the modified polypropylene may be produced by melt-kneading said crystalline polypropylene, the graft monomer and a radical initiator with an extruder. It may also be produced by heating the solution of said crystalline polypropylene in an organic solvent such as xylene together with a radical generator in an atmosphere of nitrogen with stirring, then cooling the reaction system, and filtering, washing, and drying the reaction product. It may also be produced by irradiating ultraviolet rays to said crystalline polypropylene in the presence of the graft monomer, or contacting oxygen or ozone to said crystalline polypropylene in the presence of the graft monomer.
Ethylene-propylene copolymer rubber (B)
The ethylene-propylene copolymer rubber ( B ) used in the present invention includes ethylene-propylene random copolymer rubber which contains 10-70 wt % of propylene and which has a Mooney viscosity (ML.sub.1+4 100.degree. C.) of 10-100. With a propylene content outside the above-specified range, the resulting molded article is sometimes poor in impact strength.
The ethylene-propylene random copolymer rubber can be produced by conventional methods, for example, by polymerizing the comonomers in the presence of a catalyst composed of vanadium compound and an organo-aluminum in a hydrocarbon solvent (e.g., hexane, heptane). As the vanadium compound, vanadium oxytrichloride, vadadium tetrachloride or vanadates, and as the organoaluminum, ethylaluminium sesquichloride or diethylaluminium chloride may be used.
As said ethylene-propylene random copolymer rubber, ethylene-propylene-nonconjugated diene copolymer rubbers may be used, and as the non-conjugated diene, dicyclopentadiene, 1,4-hexadiene, dicyclooctadiene, 5-methylene-norbornene, 5 ethylidene-2-norbornene are preferably used.
With a Mooney viscosity lower than 10, the resulting molded article tends to be poor in mechanical properties. With a Mooney viscosity higher than 100, the compound tends to be poor in flowability at the time of molding and hence the resulting molded article is sometimes poor in appearance.
Hydroxyl group-containing propylene oligomer (C)
The term "hydroxyl group-containing propylene oligomer (C)" used in the present invention refers to an oligomer which comprises polypropylene having hydroxyl groups. An example of the oligomer is a low molecular weight polypropylene of the same type as the above-mentioned crystalline polypropylene (A) to which hydroxyl-containing groups have been grafted. Such hydroxyl group-containing propylene oligomer may be prepared by the known methods (e.g., JP-A-61-113675, JP-A-50-160394 and JP-A-56-88403. A preferred hydroxyl group-containing propylene oligomer is the one which has a number-average molecular weight (Mn) of 2,000-20,000 and having a hydroxyl value of 10-60. Such hydroxyl group-containing propylene oligomers are commercially available, for example, from Sanyo Chemical Industries, Ltd. under a trade name of Youmex 1201H (Y1201H) or Youmex 1210 (Y1210).
Inorganic filler (D)
The inorganic filler (D) used in the present invention includes talc, mica, wollastonite, calcium carbonate, barium sulfate, magnesium carbonate, clay, alumina, silica, calcium sulfate, carbon fiber, glass fiber, metal fiber, silica sand, silicastone, carbon black, titanium oxide, magnesium hydroxide, asbestos, zeolite, molybdenum, diatomaceous earth, sericite, Shirasu, calcium hydroxide, potassium sulfite, sodium sulfate, bentonite, and graphite.
Of these inorganic filler, talc with an average particle diameter not larger than 3 .mu.m is desirable in view of its improving effects on the stiffness, impact strength at a low-temperature and appearance of the molded articles.
The Amounts of the Components
When the amount of the ethylene-propylene copolymer rubber is less than 5 parts by weight per 100 parts by weight of the mixture of the crystalline polypropylene (A) and ethylene-propylene copolymer rubber (B), the impact resistance of the molded articles is sometimes not so much improved. When the amount of the ethylene-propylene copolymer rubber is more than 90 parts by weight in 100 parts by weight of the mixture of the crystalline polypropylene (A) and ethylene-propylene copolymer rubber (B), the stiffness and heat resistance of the molded articles are sometimes reduced. Preferred range of the amount of the ethylene-propylene copolymer rubber is 5 to 40 parts by weight.
When the amount of the hydroxyl group-containing propylene oligomer (C) is less than 1 part by weight in 100 parts by weight of the mixture of the crystalline polypropylene (A) and ethylene-propylene copolymer rubber (B), the paintability, printability and binding strength of the molded articles sometimes are not improved to a sufficient extent. When the amount exceeds 30 parts by weight per 100 parts by weight of the mixture of the crystalline polypropylene (A) and ethylene-propylene copolymer rubber (B), the hydroxyl group-containing propylene oligomer (C) sometimes causes the decrease of the stiffness and heat resistance of the molded articles. Preferred range of the amount of the hydroxyl group-containing propylene oligomer is 1 to 15 parts by weight.
When the amount of the inorganic filler exceeds 40 parts by weight of the mixture of the crystalline polypropylene (A) and ethylene-propylene copolymer rubber (B), the impact strength of the molded articles is sometimes reduced. Preferred range of the amount of the inorganic filler is 2 to 30 parts.
Molding and Painting
The polypropylene resin composition of the present invention may be prepared by known methods usually used in the art. For example, solutions of the above-mentioned components are mixed together and then the solvents are evaporated off from the resulting mixture or alternatively, the composition is precipitated by adding a poor solvent to the resulting mixture. However, melt-kneading is preferable from the industrial point of view. Melt-kneading may be accomplished with a Banbury mixer, extruder, roll, or kneader.
It is preferable that the melt-kneading of the components is preceded by uniform mixing of each of the components, which may be either powder or pellets, with a tumbler or Henschel mixer. However, this preliminary mixing step may be omitted, and each of the components may directly be fed to a kneading apparatus.
The thus kneaded composition is then molded by injection molding, extrusion molding and the like. Instead of kneading the components, they may be dry-blended and then mixed during the melting step in the injection molding or extrusion molding to form shaped articles.
During the kneading step, suitable amounts of conventional additives or auxiliaries may be added to the composition. They include, for example, an anti-oxidant, UV light absorber, slip agent, pigment, antistatic agent, copper deactivator, flame retardant, neutralizing agent, foaming agent, plasticizer, and nucleating agent.
One of the striking advantages of the articles molded out of the crystalline polypropylene composition of the present invention is that once the surface of the articles is treated with water or a non-halogenated organic solvent, the articles can be painted by a paint with high compatibility. Thus, the articles do not need application of any primer onto the surface nor pre-cleaning of the surface beforehand. The non-halogenated organic solvent has a boiling point of, with increasing preference, 150.degree. C. or lower and 100.degree. C. or lower.
This surface treatment may be accomplished by applying, wiping or spraying water or said organic solvents on the surface of the molded articles or alternatively, dipping them in water or said organic solvents.
Being innoxious and incombustible, water is advantageous over other solvents from the standpoint of safety and prevention of environmental pollution.
In the present invention, there in no particular restriction with respect to the water to be used, but pure water, tap water and industrial water may be used. As the water used in the present invention, acidic or basic aqueous solutions may also be used.
Examples of the non-halogenated organic solvents having a boiling point not higher than 150.degree. C. include alcohols (e.g., ethanol and isopropyl alcohol), aliphatic hydrocarbons (e.g., hexane, heptane, and cyclohexane), aromatic hydrocarbons (e.g., toluene), ketones (e.g., acetone and methyl ethyl ketone), esters (e.g., ethyl acetate), petroleum benzine, and kerosene.
Of these solvents, water, isopropyl alcohol, and cyclohexane are preferable. Halogenated organic solvents are undesirable due to their effects on ozone depletion or the global environmental problems.
The solvent having a boiling point higher than 150.degree. C. is not preferable because they cannot be rapidly evaporated after the solvent-treatment has been finished.
After the molded articles have been treated with water or the solvents, they are dried, for example, by air-drying, and then coated with a melamine paint, urethane paint or acrylic paint. The melamine paint and urethane paint are preferable. The preferable melamine paint is of curable type, including a polyester melamine paint of flexible type, which is commonly used for bumpers.
The urethane paint includes an acryl urethane paint, a polyester urethane paint, and a urethane paint in the form of a single solution.
Although the molded articles of the present invention can well be painted without a primer layer as mentioned above, it can also be well painted in the conventional manner in which a primer is applied before applying paints. However, the composition of the present invention can well be painted without pre-cleaning with said hologanated hydrocarbons such as 1,1,1-trichloroethane before applying a primer.
After the paints have been applied, the molded articles are usually baked at 60.degree. C. to 150.degree. C. for 20 minutes to 1 hour.

The invention will be described in more detail with reference to the following examples, which are not intended to restrict the scope of the invention.
EXAMPLE 1
A mixture of 60 parts by weight of propylene-ethylene block copolymer having a melt index of 30 g/10 min and an ethylene content of 3.2 wt % and containing propylene-ethylene copolymer units having an ethylene content of 24.7 wt % and an intrinsic viscosity of 6.4 dl/g measured with tetralin solution at 135.degree. C., and 40 parts by weight of an ethylene-propylene random copolymer rubber having a propylene content of 45 wt % and a Mooney viscosity (ML.sub.1+4 100 .degree. C.) of 30 were melt-kneaded at 180.degree. C. for 8 minutes with a 16-liter Banbury mixer. The resulting mixture was rolled and cut into pellets by a sheet cutter to obtain a master batch (hereinafter MB) in pellet form.
To the master batch was added the same propylene-ethylene block copolymer to produce the composition comprising 46 parts by weight of the propylene-ethylene block copolymer and 29 parts by weight of the ethylene-propylene random copolymer rubber. The mixture was further mixed with 5 parts by weight of a hydroxyl group-containing propylene oligomer having a molecular weight of 12,000 and a hydroxyl value of 21.5 (Youmex 1201H manufactured by Sanyo Chemical Industries, Ltd.) and 20 parts by weight of talc having an average particle diameter of 2.5 .mu.m. They were uniformly mixed with a Henschel mixer and then melt-mixed at 220.degree. C. with a continuous twin-screw mixer (TEX 44SS 30BW-2V, made by Japan Steel Works, Ltd.) to give pellets. The resulting pellets were injection-molded into flat plates (100.times.400.times.3 mm thick) at 220.degree. C. with an injection molder, "Neomat 515/150" made by Sumitomo Heavy Industries, Ltd. The resulting plates were subjected to the evaluations.
From the plates were cut out 100 mm square of specimen, the surface of which was treated with cyclohexane (by wiping with gauze) and air-dried. The specimen was then coated by spraying with one-solution type urethane paint (Flexthane 101 manufactured by Nippon Bee Chemical Co., Ltd.) and baked at 120.degree. C. for 40 minutes. The coated specimen was tested for the initial adhesion as described below. The results are shown in Table 2.
Evaluation of Coatability (Initial adhesion)
In the Examples and Comparative examples, the initial adhesion of paint-coating formed on a composition was evaluated in the following manner unless otherwise is indicated:
A checker board pattern containing 100 squares (each 2 mm by 2 mm) was made on the paint-coating layer of the specimen by cutting with a razor blade. A piece of plastic adhesive tape (24 mm wide, cellophane tape manufactured by Nichiban Co., Ltd.) was applied over the squares and rapidly pulled off. By counting the number of squares remaining on the specimen, the initial adhesion of the paint-coating was evaluated.
Comparative Example 1
The same procedure as in Example 1 was repeated except that the surface treatment with cyclohexane was not performed. The results are shown in Table 2.
Comparative Example 2
The same procedure as in Example 1 was repeated except that the amount of propylene-ethylene block copolymer was changed to 51 parts by weight and the hydroxyl group-containing propylene oligomer was not used. The results are shown in Table 2.
EXAMPLE 2
The same procedure as in Example 1 was repeated except that the amount of propylene-ethylene block copolymer was changed to 41 parts by weight and the amount of hydroxyl group-containing propylene oligomer was changed to 10 parts by weight. The results are shown in Table 2.
EXAMPLE 3
The same procedure as in Example 1 was repeated except that the amount of propylene-ethylene block copolymer was changed to 41 parts by weight, the amount of ethylene-propylene random copolymer rubber was changed to 34 parts by weight, the amount of hydroxyl group-containing propylene oligomer was changed to 5 parts by weight, and the amount of talc was changed to 20 parts by weight. The results are shown in Table 2.
Comparative Example 3
The same procedure as in Example 3 was repeated except that the surface treatment with cyclohexane was not performed. The results are shown in Table 2.
Comparative Example 4
The same procedure as in Example 3 was repeated except that the amount of propylene-ethylene block copolymer was changed to 46 parts by weight and the hydroxyl group-containing propylene oligomer was not used. The results are shown in Table 2.
EXAMPLE 4
The same procedure as in Example 1 was repeated except that the amount of propylene-ethylene block copolymer was changed to 51 parts by weight and the amount of ethylene-propylene random copolymer rubber was changed to 24 parts by weight. The results are shown in Table 2.
Comparative Example 5
The same procedure as in Example 4 was repeated except that the surface treatment with cyclohexane was not performed. The results are shown in Table 2.
Comparative Example 6
The same procedure as in Example 4 was repeated except that the amount of propylene-ethylene block copolymer was changed to 56 parts by weight and the hydroxyl group-containing propylene oligomer was not used. The results are shown in Table 2.
EXAMPLE 5
The same procedure as in Example 1 was repeated except that the amount of propylene-ethylene block copolymer was changed to 66 parts by weight and talc was not used. The results are shown in Table 2.
Comparative Example 7
The same procedure as in Example 5 was repeated except that the surface treatment with cyclohexane was not performed. The results are shown in Table 2.
Comparative Example 8
The same procedure as in Example 5 was repeated except that the amount of propylene-ethylene block copolymer was changed to 71 parts by weight and the hydroxyl group-containing propylene oligomer was not used. The results are shown in Table 2.
TABLE 1______________________________________Components and the amounts Components(weight parts)Example No. A B C D______________________________________Example 1 46 29 5 20Comparative Example 1 46 29 5 20Comparative Example 2 51 29 -- 20Example 2 41 29 10 20Example 3 41 34 5 20Comparative Example 3 41 34 5 20Comparative Example 4 46 34 -- 20Example 4 51 24 5 20Comparative Example 5 51 24 5 20Comparative Example 6 56 24 -- 20Example 5 66 29 5 --Comparative Example 7 66 29 5 --Comparative Example 8 71 29 -- --______________________________________ (A): Propyleneethylene block copolymer (B): Ethylenepropylene random copolymer rubber (C): Hydroxyl groupcontaining propylene oligomer (D): Talc
TABLE 2______________________________________Evaluation of Initial Adhesion Cyclo- InitialExample No. hexane Paint Adhesion (%)______________________________________Example 1 yes Flexthane 101 79Comparative Example 1 no Flexthane 101 0Comparative Example 2 yes Flexthane 101 0Example 2 yes Flexthane 101 87Example 3 yes Flexthane 101 96Comparative Example 3 no Flexthane 101 0Comparative Example 4 yes Flexthane 101 0Example 4 yes Flexthane 101 56Comparative Example 5 no Flexthane 101 0Comparative Example 6 yes Flexthane 101 0Example 5 yes Flexthane 101 75Comparative Example 7 no Flexthane 101 0Comparative Example 8 yes Flexthane 101 0______________________________________
EXAMPLE 6
The following components were uniformly mixed using a Henschel mixer.
48 parts by weight of the same propylene-ethylene block copolymer as used in Example 1
25 parts by weight of ethylene-propylene random copolymer rubber containing 27 wt % propylene and having a Mooney viscosity (ML.sub.1+4 100.degree. C.) of 45
7 pats by weight of the hydroxyl group-containing propylene oligomer having a molecular weight of 4000 and a hydroxyl value of 50 (Youmex 1210 from Sanyo Chemical Industries, Ltd.)
20 parts by weight of talc having an average particle diameter of 2.5 .mu.m
The resulting mixture was then melt-mixed at 220.degree. C. and pelletized with a continuous twin-screw mixer (TEX 44SS 30BW-2V, made by Japan Steel Works, Ltd.). The resulting pellets were injection molded into flat plates (100.times.400.times.3 mm thick) at 220.degree. C. using an injection molder, "Neomat 515/150" made by Sumitomo Heavy Industries, Ltd.
A 100 mm square was cut out of from the flat plate. The surface of the specimen was treated with water or solvent as shown in Table 3 (by wiping with gauze), and then by air-dried. The specimen was coated by spraying one-solution type urethane paint (Flexthane 101, trade name of Nippon Bee Chemical Co., Ltd.) and then baked at 120.degree. C. for 40 minutes. The coated specimen was tested for the evaluation of the initial adhesion. The results are shown in Table 3.
TABLE 3______________________________________ InitialTreatment Paint Adhesion (%)______________________________________Water Flexthane 101 98Isopropyl alcohol Flexthane 101 92Cyclohexane Flexthane 101 98Kerosene Flexthane 101 98______________________________________
EXAMPLES 7-16
Each of the components A to D given in Table 9 and 11 were blended with a Henschel mixer and then melt-kneaded with a 44 mm-twin screws-extruder at 220.degree. C. to form pellets. Using these pellets, test pieces and plates were molded by injection molding under the conditions A and B shown in Table 8 and then subjected to the evaluation testings. The results are given in Tables 10 and 12.
The evaluation of the specimens were conduced in the following methods:
(1) Melt Flow Rate (MFR)
Melt flow rates of specimens were determined according to the method of JIS K6758. The measurements were conducted at a temperature of 230.degree. C. unless otherwise indicated. The applied load was 2.16 Kg.
(2) Tensile Strength (TS)
Tensile strengths of specimens were determined according to ASTM D638. Sample plates of 3.2 mm in thickness were produced by injection molding and their tensile strengths at yield points were measured. The measurements were conducted at a temperature of 23.degree. C. unless otherwise indicated.
(3) Flexural Test (FT)
Flexural test was conducted according to the method of JIS K 7203. Sample plates of 6.4 mm in thickness were formed by injection molding. Their flexural modulus (FM) and flexural strength (FS) were measured at a span length of 100 mm with a loading rate of 2.0 mm/min. The measurements were conducted at a temperature of 23.degree. C. unless otherwise is indicated. When the measurements were conducted at a temperature other than 23.degree. C. the samples were kept in a temperature bath maintained to a predetermined temperature for 30 minutes before the measurements.
(4) Izod Impact Strength (IIS)
Izod impact strength was determined according to the method of JIS K7110. The impact strength was measured with the notched specimens of 6.4 mm in thickness prepared by injection molding. The measurements were conducted at a temperature of 23.degree. C. unless otherwise is indicated. When the measurements were conducted at a temperature other than 23.degree. C., the specimens were kept in a temperature bath maintained to a predetermined temperature for 2 hours before the measurements.
(5) Heat Deformation Temperature (HDT)
Heat Deformation Temperature was determined according to JIS K7207 with a fiber stress of 4.6 Kg/cm.sup.2.
(6) Appearance (AP)
The flow marks and weld marks formed on the surface of the molded plates (100 mm in width, 400 mm in length, 3 mm in thickness) prepared by injecting the resin composition through a single side gate at the shorter side and double side gates formed at each of the shorter sides, respectively, were observed with the unaided eyes. The results are given in the Tables 10 and 11 in which INSG represents that the flow or weld marks are insignificant and SG represents significant flow or weld marks.
(7) Paintability (PT)
Plates were molded in the same manner as in the above testing (6). One day thereafter, the plates were air-blown. Commercially available primer, (RB 115, manufactured by Nippon Bee Chemical Co. Ltd.) was spread onto the plates to the thickness of 5 to 10.mu. with a spray gun and the primer-sprayed plate was baked at 90.degree. C. for 30 minutes in an oven. As the second coating, commercially available two solutions type-urethane paint (R 255, manufactured by Nippon Bee Chemical Co. Ltd. metallic paint) was spread onto the baked plates to the thickness of 30 to 35.mu., and, 10 minutes thereafter, Clear (R266, manufactured by Nippon Bee Chemical Co. Ltd.) was spread to the thickness of 35 to 40.mu.. After having been baked at 90.degree. C. for 30 minutes in an oven, the resulting plates were allowed to stand at a room temperature for 1 day and then subjected to the test of initial adhesion of the paint-coating and gasohol-resistance test.
(8) The Initial Adhesion of Paint-Coating (IA)
One hundred 1 mm-squares (10 in longitudinal direction and 10 in lateral) were formed on the surface of the paint-coating of the specimen with a razor blade, a plastic adhesive tape (Nichiban CO., Ltd. Cellophane) of 24 mm in width was tightly attached on the specimen to cover all the squares and then quickly lifted up to 90 degree to uncover them. The percentage of the squares remaining on the specimen was then determined.
(9) Gasohol-Resistance (GRS) Test
A sample plate (25 mm in width and 75 mm in length) was cut out from the paint-coated specimen and immersed in gasohol (gasoline/ethanol=90/10) at a room temperature and the time when the paint-coating started to separate was measured.
TABLE 4______________________________________Composition of crystalline ethylene-propylene blockcopolymer ACrystallinepolypropylene Ethylene-propyleneunits random copolymer units Xylene-soluble Content E/PNo. [.eta.]p Q portion(w %) in A (w %) (W %)______________________________________PP-1 1.02 3.5 0.9 12 28/72PP-2 0.70 3.4 0.9 11.5 30/70PP-3 1.25 7.1 1.3 16 28/72PP-4 0.98 3.5 2.1 16 38/62PP-5 1.20 3.6 0.9 1 42/58PP-6 1.11 3.7 1.0 25 38/62PP-7 1.15 3.6 1.0 17 70/30PP-8 2.31 3.7 1.1 12 30/70______________________________________ E/P: Ethylene/propylene
TABLE 5______________________________________Ethylene-propylene random copolymer B Amount of IodineNo. ML.sub.1+4 100.degree. C. propylene value Catalyst______________________________________EPR-1 45 28 -- vanadiumEPR-2 30 45 -- vanadiumEPR-3 30 30 18(ENB) vanadiumEPR-4 77 45 10(ENB) vanadiumEPR-5 30 68 -- titaniumEPR-6 120 30 1(ENB) vanadiumEPR-7 55 15 -- vanadium______________________________________
TABLE 6______________________________________Hydroxyl group-containing polypropylene oligomer C Molecular Hydroxyl SpecificTrade name weight (MW) value gravity______________________________________Youmex 1201H 12000 21.5 0.951201 4000 50 0.95______________________________________
TABLE 7______________________________________Inorganic fillersFiller Average particle size (.mu.m)______________________________________Talc-A 2.2Talc-B 4.1calcium carbonate 1.9barium sulfate 0.8wollastonite 8.2______________________________________
TABLE 8______________________________________The molding conditions of the preparations of specimens Molding conditions A B______________________________________Molding device Toshiba IS150E Neomat 515/150Die test pieces plates 100 .times. 400 .times. 3 mm Tensile strength 1 or 2 side gates Flexural Test Izod Impact StrengthTemperature 220.degree. C. 220.degree. C.Initial pressure 500 Kg/cm.sup.2, 5 sec. 700 Kg/cm.sup.2, 5 sec.and timeSecondary pressure 300 Kg/cm.sup.2, 5 sec. 500 Kg/cm.sup.2, 5 sec.and timeCooling time 30 sec 30 secDie temperature 50.degree. C. 50.degree. C.Screw rotation 87 rpm 80 rpmspeed______________________________________
TABLE 9__________________________________________________________________________Compositions Components (weight parts)Example No. A (WP) B (WP) C (WP) D (WP)__________________________________________________________________________Example 7 PP-1 60 EPR-1 30 Youmex 5 talc-A 5 1201HComparative PP-2 60 EPR-1 30 1201H 5 talc-A 5example 9Comparative PP-3 60 EPR-1 30 1201H 5 talc-A 5example 10Comparative PP-4 60 EPR-1 30 1201H 5 talc-A 5example 11Comparative PP-5 60 EPR-1 30 1201H 5 talc-A 5example 12Comparative PP-6 60 EPR-1 30 1201H 5 talc-A 5example 13Comparative PP-7 60 EPR-1 30 1201H 5 talc-A 5example 14Comparative PP-8 60 EPR-1 30 1201H 5 talc-A 5example 15Comparative PP-1 90 -- -- 1201H 5 talc-A 5example 16Comparative PP-1 30 EPR-1 60 1201H 5 talc-A 5example 17Comparative PP-1 65 EPR-1 30 -- talc-A 5example 18Comparative PP-1 45 EPR-1 30 1201H 20 talc-A 5example 19Comparative PP-1 65 EPR-1 30 1201H 5 --example 20Comparative PP-1 25 EPR-1 30 1201H 20 talc-A 40example 21__________________________________________________________________________
TABLE 10______________________________________ MFR TS TL FM FSExample No. (g/10 min) (MPa) (%) (MPa) (MPa)______________________________________Example 7 15 20.0 >500 1170 22.1Comparative 34 21.6 160 1290 23.5example 9Comparative 9.8 19.1 110 1030 20.6example 10Comparative 13 18.6 >500 880 19.6example 11Comparative 10.5 23.0 400 1390 25.0example 12Comparative 12 18.6 >500 880 20.1example 13Comparative 11 20.6 >500 1170 23.1example 14Comparative 1.3 19.6 >500 1030 21.0example 15Comparative 28 29.9 80 1780 42.7example 16Comparative 0.5 5.9 >500 206 6.9example 17Comparative 14 20.6 >500 1200 22.6example 18Comparative 17 18.6 350 1080 19.6example 19Comparative 16 18.1 >500 840 19.1example 20Comparative 4.3 16.7 125 2600 20.6example 21______________________________________
TABLE 10-1__________________________________________________________________________ IIS (J/M) HDT flow weld IA GRSExample No. 23.degree. C. -30.degree. C. (.degree.C.) mark mark (%) (min)__________________________________________________________________________Example 7 NB 93 107 INSG INSG 100 >120Comparative 255 52 110 INSG INSG 100 >120example 9Comparative NB 140 105 INSG SG 95 70example 10Comparative NB 83 95 INSG INSG 100 >120example 11Comparative 186 48 112 INSG SG 85 60example 12Comparative NB 265 98 SG INSG 100 >120example 13Comparative 285 50 104 SG INSG 88 70example 14Comparative NB NB 103 SG SG 100 60example 15Comparative 62 32 138 INSG INSG 25 <30example 16Comparative NB NB UM SG SG 75 <30example 17Comparative NB 89 108 INSG INSG 80 <30example 18Comparative 265 50 101 SG SG 85 >120example 19Comparative NB 88 98 INSG INSG 100 55example 20Comparative 108 34 109 SG SG 75 50example 21__________________________________________________________________________ NB: not broken INSG: insignificant UM: impossible to determine SG: significant
TABLE 11__________________________________________________________________________Compositions Components (weight parts)Example No. A (WP) B (WP) C (WP) D (WP)__________________________________________________________________________Example 8 PP-1 60 EPR-2 30 Youmex 5 talc-A 5 1201HExample 9 PP-1 60 EPR-3 30 1201H 5 talc-A 5Example 10 PP-1 60 EPR-4 30 1201H 5 talc-A 5Example 11 PP-1 60 EPR-5 30 1201H 5 talc-A 5Comparativeexample 22 PP-1 60 EPR-6 30 1201H 5 talc-A 5Comparativeexample 23 PP-1 60 EPR-7 30 1201H 5 talc-A 5Example 12 PP-1 60 EPR-1 30 1210 5 talc-A 5Example 13 PP-1 60 EPR-1 30 1201H 5 talc-B 5Example 14 PP-1 60 EPR-1 30 1201H 5 calcium 5 carbonateExample 15 PP-1 60 EPR-1 30 1201H 5 barium 5 sulfateExample 16 PP-1 60 EPR-1 30 1201H 5 wollastonite 5__________________________________________________________________________
TABLE 12______________________________________ MFR TS TL FM FSExample No. (g/10 min) (MPa) (%) (MPa) (MPa)______________________________________Example 8 11 15.2 >500 980 17.2Example 9 10 18.6 >500 1030 20.1Example 10 12 17.7 >500 980 18.6Example 11 9 17.7 >500 1030 20.6Comparative 5.3 18.6 >500 1060 20.1example 22Comparative 13 22.1 180 1300 24.0example 23Example 12 16 19.5 >500 1140 21.5Example 13 11 19.6 >500 1080 21.6Example 14 14 17.9 >500 960 20.1Example 15 17 18.6 >500 950 19.6Example 16 16 19.1 >500 1000 20.6______________________________________
TABLE 12-1__________________________________________________________________________ IIS (J/M) HDT flow weld IA GRSExample No. 23.degree. C. -30.degree. C. (.degree.C.) mark mark (%) (min)__________________________________________________________________________Example 8 NB 128 100 INSG INSG 100 >120Example 9 NB 98 105 INSG INSG 100 >120Example 10 NB 72 100 INSG INSG 100 >120Example 11 NB 118 104 INSG INSG 100 >120Comparative NB 123 107 SG INSG 75 <30example 22Comparative 284 53 113 INSG INSG 83 40example 23Example 12 NB 98 106 INSG INSG 100 >120Example 13 NB 78 105 INSG INSG 100 >120Example 14 NB 226 100 INSG INSG 100 >120Example 15 NB 186 100 INSG INSG 100 >120Example 16 NB 137 102 INSG INSG 100 >120__________________________________________________________________________ NB: not broken INSG: insignificant SG: significant

Number	Date	Country	Kind
4-327733	Dec 1992	JPX
5-227491	Sep 1993	JPX

Number	Name	Date
4146590	Yamamoto et al.	Mar 1979
4735988	Takada et al.	Apr 1988
4863995	Murakami et al.	Sep 1989
4957968	Adur et al.	Sep 1990
5331046	Chang et al.	Jul 1994

Number	Date	Country
20336780	Oct 1989	EPX
0429236	May 1991	EPX
2275487	Jan 1976	FRX
62-257945	Nov 1987	JPX

Polypropylene resin composition having an improved compatibility with paint-coatings and a paint-coated article thereof

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