JP2003020352A - Coated parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated parts for automobiles which has an excellent paint adhesive strength and also a high-degree mechanical strength balance especially between the high rigidity and low-temperature impact performance by a simplified coating method of directly applying a paint. SOLUTION: An injection-molded body for the coated parts is obtained by injection-molding a propylene-based resin composition comprising 20-40 wt.% of (a) a propylene/ethylene block copolymer consisting of 80-95 wt.% of propylene solely polymerized portions and 5-20 wt.% of ethylene/propylene randomly copolymerized portions, 20-40 wt.% of (b) and ethylene/octene copolymer, 0-20 wt.% of (c) a talc which has a length of not more than 15 μm, an average particle diameter of 1-10 μm and an average aspect ratio of not less than 3, and 20-40 wt.% of (d) a modified propylene-based polymer, and the injection-molded body has a surface with an abundance of the oxygen atom/the carbon atom of not less than 0.008; the coated parts is obtained by applying directly on the injection-molded body a polyurethane paint composition which is so blended that a ratio of the hydroxyl-group equivalent weight and the isocyanate-group equivalent weight may become not more than 5.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an injection-molded article obtained by injecting a specific propylene-based resin composition having excellent paintability and a high degree of mechanical strength balance (rigidity and low-temperature impact property). In particular, the present invention relates to a coated part obtained by directly applying a specific polyurethane coating composition, and particularly to a coated part for automobile exterior.

[0002]

2. Description of the Related Art Conventionally, in many cases, propylene-based resin automobile parts such as fenders, bumpers, spoilers, instrument panels, etc. are put to practical use after being wholly or partially coated. However, since these propylene-based resin materials do not have polar groups in the structure of the materials themselves, it is difficult to obtain a practical level of paint adhesion strength when the paint is directly applied. Therefore, such propylene-based resin materials are often
The coating adhesion performance was improved by applying a primer or performing plasma treatment.

However, such a coating method has conventionally had the following problems. In the primer coating method, since an expensive primer must be used and the number of coating steps increases,
There was a drawback that the coating cost was high. On the other hand, in the plasma processing method, since a high degree of vacuum is required, an expensive device must be installed, and the cost increase cannot be avoided because of the batch method. In addition, recently, molded products with complicated shapes have been required, but it is difficult to perform uniform plasma treatment on molded products with such complicated shapes, and the adhesion of paint when contacted with foreign matter. However, the coating performance may vary and the handling is very inconvenient.

Therefore, if it is possible to omit the steps of applying the primer and the plasma treatment in the coating of the propylene resin molded product, it is possible to simplify the coating process, improve the working environment, and reduce the cost. From that,
Much research has been done so far so as to omit these steps. For example, a resin composition containing a hydroxyl group-modified polypropylene (Japanese Patent Publication No. 5-64660),
A method using a resin composition containing an unsaturated carboxylic acid-grafted polypropylene (JP-A-5-59231), a resin composition containing an ethylene-based elastomer and polypropylene to which a charging agent is added (JP-A-6-9835), and the like. Is proposed. However, in the case of moldings made from these compositions, when the coating is directly applied by omitting the primer coating, the coating adhesion strength is not always sufficient, and particularly good molding processability (injection molding fluidity) and high In order to obtain mechanical strength balance, especially high rigidity and low temperature impact properties at the same time, treatments such as primer coating and plasma treatment were practically necessary in order to obtain a practically high paint adhesion strength.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to overcome the drawbacks of the prior art, omit the primer coating on the injection-molded article, and apply the coating material directly to a simplified coating method. It is intended to provide a coated part for an automobile, which has excellent molding processability (fluidity of injection molding), high mechanical strength balance, particularly high rigidity, and low temperature impact characteristics.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve such objects as the simplification of the coating process, and as a result, injection-molded a specific propylene resin composition. By directly applying a specific polyurethane coating composition to the injection molded product obtained as a result, it is possible to obtain a coated part that has practically sufficient paint adhesion strength and has a high degree of mechanical balance (rigidity and low temperature impact characteristics). The inventors have found that they can be obtained and completed the present invention.

That is, the present invention provides the following components (a) to
An injection-molded article obtained by injection-molding a propylene-based resin composition comprising (d), wherein the oxygen atom / carbon atom abundance ratio on the surface of the molded article measured by ESCA (X-ray photoelectron spectroscopy) is 0.008. In the propylene resin injection-molded product as described above, the coating film forming component has a hydroxyl value of component (e) of 50 to 90.
KOH mg / g active hydrogen-containing coating resin and component (f)
A coated part obtained by directly applying a polyurethane coating composition containing an isocyanate compound and having a ratio of a hydroxyl group equivalent of component (e) to an isocyanate group equivalent of component (f) of 5.0 or less. is there. Component (a): crystalline propylene homopolymer portion 80 to 95
5% by weight and fractionation with o-dichlorobenzene
Propylene / ethylene block copolymer consisting of 5 to 20% by weight of ethylene / propylene random copolymer portion represented as a component to be eluted at 0 ° C. or lower 20 to 40 parts by weight Component (b): Melting point of 40 to 60 ° C. Yes, and melt flow rate (230 ° C, 2.16kg) 0.5-1
5 g / 10 min ethylene-octene copolymer 20-4
0 parts by weight component (c): substantially the entire length is 15 μm or less, the average particle size is 1 to 10 μm, and the average aspect ratio is 3.
0 to 20 parts by weight of the above talc Component (d): A hydroxyl group-containing maleic anhydride derivative represented by the following formula is added to the propylene-based polymer in an amount of 3 parts of the entire component (d).
The number average molecular weight grafted at a ratio of up to 20% by weight is 3,
000 to 15,000 modified propylene homopolymer or block or random copolymer of the same propylene and ethylene 20 to 40 parts by weight

[0008]

[Chemical 2] (In the formula, R represents an alkylene group having 1 to 4 carbon atoms.)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. [1] Propylene-based resin composition (1) Constituent component Component (a): Propylene / ethylene block copolymer Component (a) that constitutes the propylene-based resin composition of the present invention.
The propylene / ethylene block copolymer of is a propylene / ethylene containing a crystalline propylene homopolymer portion and an ethylene / propylene random copolymer portion represented as a component eluted at 50 ° C. or less in the fractionation with o-dichlorobenzene. It is a block copolymer.

Here, the crystalline propylene homopolymer portion is 80 to 95% by weight, preferably 85 to 95% by weight in the propylene / ethylene block copolymer, particularly in view of heat resistance and rigidity.
It is necessary to occupy a ratio of 95% by weight, more preferably 90 to 95% by weight, and its density is also preferably 0.9070 g / cm ³ or more in terms of heat resistance rigidity,
It is more preferably 0.9080 g / cm ³ or more.

The ethylene / propylene random copolymer portion is contained in the propylene / ethylene block copolymer in an amount of 5 to 20% by weight, preferably 5 to 15% by weight, especially in view of coating adhesion and impact resistance. , And more preferably 5 to 1
The ethylene content is preferably 20 to 80% by weight, more preferably 30 to 80% by weight from the viewpoint of paint adhesion and impact resistance.
Is. Further, the weight average molecular weight (Mw) of the propylene / ethylene random copolymerization portion is preferably 800,000 or less from the viewpoint of obtaining a higher paint adhesion.

The content of the propylene / ethylene copolymer portion in the whole propylene / ethylene block copolymer is o
-It is expressed as the amount of components eluted at a temperature of 50 ° C or less in the fractionation with dichlorobenzene, and is measured as follows.

5 g of propylene / ethylene block copolymer and 2,6-di-t-butyl-p-phenol 1.5
g was added to 1.5 liters of o-dichlorobenzene to give 14
Dissolve at a temperature of 0 ° C. and filter with a polytetrafluoroethylene filter. Then, after re-dissolving at the same temperature, 300 g of Celite is added and the temperature is lowered to room temperature with stirring to coat the surface of Celite. Then, the celite was packed in a cylindrical column, and o-dichlorobenzene to which 2,6-di-t-butyl-p-phenol was added at the same concentration was transferred into the column and eluted at a temperature of 50 ° C. Sort by things. After fractionation, a large amount of methanol is added, filtered through a polytetrafluoroethylene filter, dried in vacuum, and the propylene / ethylene random copolymer portion is weighed.

The weight average molecular weight (Mw) is measured by a method of measuring the components eluted at 50 ° C. or lower by gel permeation chromatography (GPC) in the above-mentioned fractionation with o-dichlorobenzene. is there. The ethylene content value is measured by infrared spectrum analysis method, and the melt flow rate (MFR) value is measured according to JIS-K7210 (230 ° C., 2.16 g).

The propylene / ethylene block copolymer as the component (a) is produced by slurry polymerization, gas phase polymerization or liquid phase bulk polymerization using a highly stereoregular polymerization catalyst. The polymerization is relatively easy to control the Mw of the ethylene / propylene copolymerization portion, and 800,0
Those of 00 or less easily polymerize. As the polymerization method for producing the propylene / ethylene block copolymer, either batch polymerization or continuous polymerization can be adopted, but rather continuous polymerization is preferred. When producing this propylene / ethylene block copolymer, either part may be polymerized first, but first, a crystalline propylene homopolymer part is formed by homopolymerization of propylene, and then propylene and ethylene are polymerized. Those having an ethylene / propylene copolymerized portion formed by random copolymerization of are preferable in terms of quality.

Specific polymerization methods include Mg, Ti,
A solid component containing halogen as an essential component, an organoaluminum compound component, and a catalyst in which an organosilicon compound is used in combination to carry out homopolymerization of propylene, and then perform random copolymerization of propylene and ethylene You can

The propylene / ethylene block copolymer contains other unsaturated compounds such as α-olefins such as butene-1, vinyl esters such as vinyl acetate, etc. within a range that does not impair the effects of the present invention. It may be a ternary or more copolymer contained or a mixture thereof.

Further, the MFR of this propylene / ethylene block copolymer is preferably 10 g / 10 minutes or more in order to impart good moldability, and 15
g / 10 minutes or more is more preferable, and especially 20 g /
It is preferably 10 minutes or more.

Here, the MFR is usually set by controlling various conditions such as temperature and pressure at the time of polymerization, but another method, for example, treatment adjustment of the polymer after the polymerization is performed by using various peroxides. You can also do it. In this case, the peroxide preferably has a 10-hour half-life of 100 ° C. or higher and a 1-minute half-life temperature of the melting point of the propylene polymer or higher. Examples of such peroxides include cumene hydroperoxide and Examples include diisopropyl hydrobenzene hydroperoxide, 1,3-bis (t-butylperoxy-isopropyl) benzene, dicumyl peroxide and the like. It should be noted that the adjustment of the MFR is more preferable than the peroxide treatment adjustment method under the polymerization conditions from the viewpoint of the paint adhesion performance of the molded product. In the former case,
It is relatively easy to control the Mw of the ethylene / propylene random copolymerization part.

Component (b): Ethylene / octene copolymer rubber Component (b) constituting the propylene resin composition of the present invention
Is an ethylene / octene copolymer, particularly a low-viscosity ethylene / octene copolymer rubber. The melting point of the ethylene-octene copolymer is 40 to 60 ° C, preferably 40 to 50 ° C.

The melt flow rate (230 ° C., 2.16 kg) of the ethylene / octene copolymer is 0.
5 to 15 g / 10 minutes, preferably 1 to 30 g / 10 minutes,
Particularly preferably, it should be 5 to 10 g / 10 minutes.
Further, the octene content in the ethylene-octene copolymer is preferably 18 to 50% by weight, more preferably 1
It is 8 to 30% by weight, particularly preferably 18 to 28% by weight.

The melting point of the ethylene-octene copolymer,
If the MFR of less than the above range or the octene content of less than the above range is used, the paint adhesion of the injection molded article becomes insufficient, which is unsuitable. If the melting point or MFR exceeds the above range, the mechanical properties are insufficient and it is unsuitable. If the octene content exceeds the above range, the paint adhesion of the molded product becomes insufficient, which is unsuitable. The ethylene / octene copolymer rubber may be in the shape of a veil, pellet, crumb, or the like, and its manufacturing method is not particularly limited. The octene content is a value measured by a conventional method such as an infrared spectrum analysis method.

The blending ratio of the component (b) ethylene-octene copolymer rubber blended in the propylene resin composition of the present invention is 20 to 40% by weight, preferably 25 to 35% by weight. If the blending ratio is less than 20% by weight, the adhesiveness of the paint to the injection molded article is insufficient and unsuitable, and if it exceeds 40% by weight, the mechanical properties are insufficient and unsuitable.

Component (c): Talc Component (c) which constitutes the propylene resin composition of the present invention.
The talc is a talc having a length of substantially 15 μm or less, an average particle size of 1 to 10 μm, and an average aspect ratio of 3 or more. Talc having a length, an average particle diameter and an average aspect ratio of less than the above ranges is not suitable because the mechanical strength balance and dimensional stability of the injection-molded product become poor. As particularly preferable specific examples, the smaller the average particle size and the larger the average aspect ratio, the higher the effect of the present invention can be exhibited. Where the length of the talc is "substantially"
Means that most talc particles are in this range.

The talc is, for example, crushed talc ore with an impact type crusher or a micron type crusher, and further crushed with a micron mill,
After finely pulverized with a jet pulverizer, it is manufactured by classifying and adjusting with a cyclone or micron separator. Rough stones are preferred from China because they contain less metallic impurities. Talc can further enhance the balance between paint adhesion and mechanical strength.

Here, the average particle size of talc is a value measured using a laser light scattering type particle size distribution meter,
As such a measuring device, for example, LA manufactured by Horiba Ltd.
The -500 type is desirable because it has excellent measurement accuracy. The diameter, length and aspect ratio are values measured by a microscope or the like. Talc is a surfactant, coupling agent,
It may be surface-treated with metal soap or the like. The surface-treated talc is effective in further improving paint adhesion, mechanical strength balance, appearance of molded products and dimensional stability.

The blending ratio of the talc of the component (c) to be blended in the propylene resin composition of the present invention is 0 to 20% by weight, preferably 5 to 15% by weight. If the blending ratio exceeds the above range, the appearance and impact resistance of the molded product will be deteriorated and it will be impractical.

Component (d): Modified propylene-based polymer The modified propylene-based polymer of the component (d) used in the propylene-based resin composition of the present invention is a hydroxyl group-containing maleic anhydride derivative represented by the following formula: In the propylene-based polymer, 3 to 20% by weight of the total of the component (d), preferably 5 to
It is a modified propylene copolymer grafted at a ratio of 20% by weight, more preferably 9 to 15% by weight. If the amount of the hydroxyl group-containing maleic anhydride derivative is less than 3% by weight, the coating property of the injection-molded article is insufficient and unsuitable, and if it exceeds 20% by weight, the mechanical properties are insufficient and unsuitable.

[0029]

[Chemical 3] (In the formula, R represents an alkylene group having 1 to 4 carbon atoms.)

Specific examples of the hydroxyl group-containing maleic anhydride derivative include N- (2-hydroxyethyl) maleimide.

Here, the propylene-based polymer in the main chain portion of the polypropylene-based polymer has a number average molecular weight of 3,0.
00-15,000, preferably 5,000-10,0
00, which is a propylene homopolymer, a propylene / ethylene block copolymer, or a propylene / ethylene random copolymer.

The method for producing the modified propylene polymer is not particularly limited. For example, after thermally oxidizing a propylene-based polymer in advance, graft polymerization of the hydroxyl group-containing maleic anhydride derivative, a method of grafting in an extruder or a solution, after grafting maleic anhydride on a propylene-based polymer, The method of denaturing with ethanolamine etc. can be mentioned.

The proportion of the modified propylene polymer as the component (d) to be blended in the propylene resin composition of the present invention is 20 to 40% by weight, preferably 25 to 35% by weight. If the compounding ratio exceeds the above range, the mechanical strength balance (rigidity, low-temperature impact property) of the molded product becomes poor,
It is not practical.

Optional Components In the propylene resin composition of the present invention, in addition to the above components (a) to (d), the propylene resin composition of the present invention may be added to the extent that the effects of the present invention are not significantly impaired or in order to further improve the performance. The following optional additives and compounding ingredients can be added. Specifically, pigments for coloring, antioxidants, antistatic agents, flame retardants, dispersants, light stabilizers, nucleating agents, various resins other than the above components (a) to (d), styrene / ethylene /
Various elastomers such as butylene / styrene block copolymer, styrene / ethylene / propylene block copolymer, styrene / ethylene / propylene / styrene block copolymer, styrene / ethylene / butylene random copolymer, and other styrene elastomers A compounding material such as a filler can be used.

(2) Production of Propylene Resin Composition The above components (a) to (d) are blended in the above blending ratio to prepare a single screw extruder, a twin screw extruder, a Banbury mixer, a roll mixer, a Brabender plast. The propylene-based resin composition for coating of the present invention can be obtained by kneading and granulating using an ordinary kneader such as a graph or a kneader. In this case, it is preferable to select a kneading / granulating method capable of improving the dispersion of each component, and the kneading / granulating is usually performed using a twin-screw extruder. During this kneading / granulation, the above-mentioned components (a) to (d) may be kneaded at the same time, or each component may be divided in order to improve the performance.
It is also possible to knead and then knead and granulate the remaining components.

(3) Injection-molded article of polypropylene-based resin composition The molding method of the polypropylene-based resin composition of the present invention is as follows.
It is molded by applying an injection molding method generally practiced in the field of synthetic resins. ESC of the obtained injection molded body
The oxygen atom / carbon atom abundance ratio of the surface of the molded product measured by A (X electron front spectroscopy) is 0.008 or more, preferably 0.
It is 01 or more. Oxygen atom / carbon atom abundance ratio is 0.00
When it is less than 8, the paint adhesion of the injection-molded article becomes insufficient, which is unsuitable.

[II] Polyurethane Coating Composition (1) Constituent Components In the present invention, the polyurethane coating composition directly applied to the injection-molded article made of the above resin composition has a coating film forming component as the following component (e): It contains a mixture of components (f).

Component (e): Resin for active hydrogen-containing paint Component (e) constituting the polyurethane paint composition of the present invention
The active hydrogen-containing coating resin of No. 1 has a hydroxyl value of 50 to 90K.
There is no particular limitation as long as it is within the range of OH mg / g, but among them, acrylic polyol and polyester polyol are preferable.

The acrylic polyol contains a (meth) acrylic monomer (A) having a hydroxyl group, and optionally has a carboxyl group (meth) copolymerizable with the monomer (A).
Acrylic monomer (B), having ester group (meth)
It is obtained by copolymerizing an acrylic monomer (C) and a vinyl monomer (D) other than (meth) acrylic.

Examples of the (meth) acrylic monomer (A) having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and ε-caprolactone adducts thereof. And the like, and may be used alone or in combination of two or more as required.

As the (meth) acrylic monomer (B) having a carboxyl group, for example, (meth) acrylic acid and the like can be mentioned, and only one kind or, if necessary, 2
You may use together 1 or more types.

Examples of the (meth) acrylic monomer (C) having an ester group include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and isobutyl (meth) acrylate. , Lauryl (meth) acrylate may be mentioned, and one kind may be used alone, or two or more kinds may be used in combination as required.

The vinyl-based monomer (D) is, for example,
Examples thereof include styrene and the like, and one kind may be used alone, or two or more kinds may be used in combination as required.

Acrylic polyols are the above-mentioned (meth) acrylic monomers (A) to (C) and vinyl monomers (D).
Therefore, it can be obtained by appropriately selecting and copolymerizing the monomers.

The polyester polyol can be obtained, for example, by condensing a polyfunctional alcohol (a), a polyfunctional carboxylic acid (b) or an anhydride thereof, and if necessary, a monofunctional carboxylic acid (c).

Examples of the polyfunctional alcohol (a) include ethylene glycol, neopentyl glycol,
Examples thereof include 1,6-hexanediol and trimethylolpropane. One type may be used alone, or two or more types may be used in combination as necessary.

Examples of the polyfunctional carboxylic acid (b) include isophthalic acid, trimellitic acid and adipic acid. Examples of the anhydride of the polyfunctional carboxylic acid (b) include phthalic anhydride, succinic anhydride and the like. These may be used alone or in combination of two or more if necessary. The polyester polyol may contain a structural unit derived from a monofunctional carboxylic acid (c) such as palmitic acid or stearic acid.

The component (e) active hydrogen-containing coating resin is
These acrylic polyols and / or these polyester polyols are preferable, and only one of them or, if necessary, two or more thereof is selected, and the hydroxyl value thereof is 50.
It is a resin for coating containing active hydrogen containing ˜90 KOHmg / g. More specifically, the active hydrogen-containing coating resin as the component (e) is one of acrylic polyol and / or polyester polyol having a hydroxyl value of 95 to 120 KOHmg / g.
Resin (e) -1 for high hydroxyl value paint selected from only one kind or two or more kinds according to need and a hydroxyl value of 20 to 45 KO
Only one kind of Hmg / g acrylic polyol and / or polyester polyol, or if necessary, a resin (e) -2 for low hydroxyl value coating selected from two or more kinds is mixed,
The hydroxyl value of the mixed resin was adjusted to be 50 to 90 KOHmg / g. When the hydroxyl value of the component (e) is less than 50 KOHmg / g, the oil resistance becomes insufficient, and when it exceeds 90 KOHmg / g, the adhesiveness may decrease. High hydroxyl value coating resin (e) -1
If the hydroxyl value is less than 95 KOHmg / g, the oil resistance may be insufficient, and if it exceeds 120 KOHmg / g, the adhesiveness may deteriorate. If the hydroxyl value of the low hydroxyl value coating resin (e) -2 is less than 20 KOHmg / g, the oil resistance may be insufficient, and if it exceeds 45 KOHmg / g, the adhesion may decrease.

Component (f): Block Isocyanate Compound Component (f) which constitutes the polyurethane coating composition of the present invention.
The block isocyanate compound of, for example, hexamethylene diisocyanate, non-yellowing polyisocyanate such as isophorone diisocyanate, acetone oxime, methyl ethyl ketone oxime, a block compound obtained by reacting with a blocking agent such as ethyl acetoacetate acetylacetone. It is possible to use only one kind or two or more kinds in combination, if necessary.

The mixing ratio of the component (e) and the component (f) is the ratio of the hydroxyl group equivalent (OH group equivalent) of the component (e) and the isocyanate group equivalent (NCO equivalent) of the component (f) = (OH equivalent).
/ (NCO equivalent) is selected and blended so as to be 5.0 or less. If this equivalent ratio exceeds 5.0, the adhesiveness may decrease.

Other Components The polyurethane coating composition of the present invention contains a pigment for coloring. Examples of the pigment include inorganic pigments such as titanium oxide; organic pigments such as phthalocyanine blue; bright pigments such as aluminum foil; extender pigments such as talc. One kind, or two kinds as necessary. You may use together the above. There are no particular restrictions on the blending of the pigment, but it is preferably 3 to 100 parts by weight, more preferably 5 to 80 parts by weight, based on 100 parts by weight of the resin component.

In the polyurethane coating composition of the present invention, if necessary, a blocked isocyanate dissociation catalyst such as a dicarboxylic acid salt of dibutyltin; an ultraviolet absorber such as benzotriazole; an additive such as a surface conditioner; A solvent or the like can be added. The mixing ratio of these additives in the paint is not particularly limited and can be appropriately selected.

(2) Method for Producing Polyurethane Coating Composition The polyurethane coating composition is obtained by mixing the above-mentioned active hydrogen-containing coating resin, blocked isocyanate compound, blocked isocyanate dissociation catalyst and pigment. If necessary, it may be a mixture of other components.

[III] Method for Molding Propylene Resin Composition The propylene resin composition is prepared by injection molding, injection compression molding,
Various molded products can be obtained by molding by compression molding or the like, but among these various molding methods, it is preferable to mold by injection molding or injection compression molding.

The molded product obtained by injection molding the propylene resin composition used in the present invention has excellent coatability, good molding processability (injection molding fluidity) and high mechanical strength. Since it can exhibit balance (rigidity and low-temperature impact characteristics), it has sufficient performance for practical use as a painted part for automobiles such as bumpers, spoilers, and fenders.

[IV] Method of Coating Polyurethane Coating Composition The method of applying the polyurethane coating composition is not particularly limited, and examples thereof include spray coating.
The paint may be diluted with a solvent or the like in advance and used.

The polyurethane paint can be baked after coating to cure the coating film. The baking temperature is usually 8
The coating film can be sufficiently cured in the range of 0 to 120 ° C.

[0058]

EXAMPLES In order to describe the coated parts of the present invention in more detail, examples will be shown and specifically described below, but the present invention is not limited to these examples.
The evaluation methods and materials used in the examples are as follows.

1. Evaluation method (1) MFR: JIS-K7210 (230 ° C, 2.1)
6 kg load).

(2) Melting point: Obtained by heating to 180 ° C. in DSC to dissolve the sample, cooling to −100 ° C. at a rate of 10 ° C./min, and further raising the temperature at 10 ° C./min. The melting point was determined from the obtained melting temperature data.

(3) Measurement of oxygen atom / carbon atom abundance ratio on the surface of the injection-molded article: ESCA measurement was carried out using a Shimadzu X-ray photoelectron spectrometer "ESCA-1000" for MgKα.
X-ray was applied to an excited X-ray source under the conditions of an output of 240 W (8 kV, 30 mA). The oxygen atom / carbon atom abundance ratio was calculated and calculated according to the following formula (1) using the areas of the C1s peak and the O1s peak of the obtained spectrum. Oxygen atom / carbon atom abundance ratio = {(O1s peak area) /2.85} / (C1s peak area) (1) where the number "2.85" in formula (1) is It is the relative sensitivity coefficient of the O1s peak in the measurement (the relative sensitivity coefficient of the C1s peak = 1.00).

(4) Evaluation of paint adhesion: A single-edged razor was used on the surface of the painted test piece that had been baked to draw 11 vertical and horizontal parallel lines at 2 mm intervals and a grid pattern of 10 was obtained.
I made zero. Cellophane adhesive tape (JIS-Z
1522) was sufficiently pressure-bonded, kept at about 30 degrees with the coating surface, and peeled off at once in front, observing the state of the part surrounded by a grid and ◯, if not peeled, partly peeled Was evaluated as Δ, and all peeled was evaluated as x.

2. Material (1) Component (a) (a) -1: 91% by weight of a crystalline polypropylene portion having a density of 0.9091 g / cm ³ and an ethylene / propylene random copolymer having an ethylene content of 39% by weight and an Mw of 780,000. A propylene / ethylene block copolymer obtained by slurry polymerization, containing 9% by weight of a polymerized portion and having an MFR of the entire component (a) of 10 g / 10 min. (A) -2: 96% by weight of a crystalline polypropylene portion having a density of 0.9091 g / cm ³ and 4% by weight of an ethylene / propylene random copolymer portion having an ethylene content of 40% by weight and an Mw of 780,000, respectively. A propylene / ethylene block copolymer obtained by slurry polymerization, which contains and has an MFR of the entire component (a) of 10 g / 10 min.

(2) Component (b) (b) -1: MFR 10 g / 10 min, octene content 23% by weight, density 0.87 g / cm ³ , melting point 50.
Low-viscosity ethylene-octene copolymer rubber that is ℃. (B) -2: MFR 3 g / 10 min, propylene content 27% by weight, density 0.86 g / cm ³ , melting point 40
Low-viscosity ethylene / propylene copolymer rubber that is below ℃.

(3) Component (c): Talc having a substantially entire length of 10 μm or less, an average particle size of 2.8 μm and an average aspect ratio of 6.

(4) Component (d) (d) -1: A propylene / ethylene random copolymer having an MFR of 50 g / 10 minutes, a number average molecular weight of 7,000 and an ethylene content of 3% by weight is thermally oxidized. Furthermore, the component (d) is introduced into both ends of the main chain and the main chain by an azo radical initiator.
A modified propylene-based polymer obtained by grafting maleic anhydride groups at a ratio of 10% by weight based on the whole, and further modifying the maleic anhydride groups with ethanolamine. (D) -2: A propylene / ethylene random copolymer having an MFR of 50 g / 10 minutes, a number average molecular weight of 7,000, and an ethylene content of 3% by weight is thermally oxidized, and the main chain of the propylene radical initiator is further treated with an azo radical initiator. The component (d) is present at both ends and in the main chain.
A modified propylene-based polymer obtained by grafting a maleic anhydride group at a ratio of 2% by weight based on the whole, and further modifying the maleic anhydride group with ethanolamine.

(5) Polyurethane coating composition: Component (e) -1: A weight average molecular weight of 50,000 having a (meth) acrylic monomer copolymerization component shown in Table 1 and a hydroxyl value of 100 KOHmg / g. Acrylic polyol. Component (e) -2: an acrylic polyol having a (meth) acrylic monomer copolymerization component shown in Table 1 and a hydroxyl value of 30 KOHmg / g and a weight average molecular weight of 30,000. Component (f): Deuranate MF-K60X which is an activated methylene block of hexamethylene diisocyanate
(Made by Asahi Kasei Corporation).

[0068]

[Table 1]

Examples 1 to 6 and Comparative Examples 1 to 8 The components (a), (b), (c) and (d) were blended in the proportions shown in Tables 2 and 3, and tetrakis was added. [Methylene-3- (3 ', 5'-di-t-butyl-
4′-hydroxyphenyl) propionate] methane was added in an amount of 0.1 parts by weight in terms of the total amount of components (a) to (d) of 100 parts by weight, and these were sufficiently mixed by a high-speed mixer. Then, using a high-speed twin-screw extruder (KCM type manufactured by Kobe Steel, Ltd.), the mixture was kneaded and granulated under a temperature condition of 210 ° C. to obtain pellets. The obtained pellets were molded at a molding temperature of 2 using an IS170 injection molding machine manufactured by Toshiba Machine.
A flat plate test piece of 150 × 70 × 3 mm was molded at 10 ° C. and an injection pressure of 50 MPa. The surface atomic abundance ratio of the test piece was measured by the ESCA method. The results are shown in Tables 2 and 3.

Next, a polyurethane paint containing the paint components in the proportions shown in Tables 2 and 3 was spray-coated on the test piece using an air spray gun so that the coating film thickness would be about 35 μm. Then, about 30 μm of clear (R-298 Nippon Bee Chemical Co., Ltd.) was similarly applied by wet on wet. The coated flat plate was baked and dried at a temperature of 100 ° C. for 20 minutes and then left at room temperature for 48 hours to obtain a test piece for evaluation of coatability. A coating adhesion test was conducted using the obtained test piece. The results are shown in Tables 2 and 3.

[0071]

[Table 2]

[0072]

[Table 3]

[0073]

The coated part of the present invention is a coated part obtained by directly coating the above-mentioned specific polyurethane coating composition on an injection-molded article obtained by injection-molding the above-mentioned specific propylene resin composition. Therefore, it exhibits excellent paintability and a high balance of mechanical strength (rigidity and impact resistance), and is used as a propylene-based resin automotive parts such as bumpers (especially large size), spoilers, fenders and instrument panels. Application can be expected.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 53/00 C08L 53/00 C09D 175/04 C09D 175/04 175/06 175/06 (72) Inventor Toru Tanaka Aichi Toyota-cho, Toyota-shi, Japan 1st Toyota Motor Co., Ltd. (72) Inventor Yoshihiro Tamura 2-14-1, Otani Otsuya, Hirata-shi, Osaka Nihon Bee Chemical Co., Ltd. (72) Seiichi Iwata Osaka 2-14-1, Otani Otsuya Otani, Hirakata-shi, Japan Inside Nihon Bee Chemical Co., Ltd. (72) Inventor Katsumi Mizuguchi 2-14-1 Otani Otsuya Otsuya, Hirakata-shi, Osaka (72nd) ) Izumi Ishii 1 Toho-cho, Yokkaichi-shi, Mie, Japan Polychem Co., Ltd. Technology Development Center (72) Inventor Yukino Zanka 1 Toho-cho, Yokkaichi-shi, Mie F-term (Japan Polychem Co., Ltd.) Reference) 4F006 AA12 AA14 AA22 AB37 BA00 CA00 CA04 DA00 4F100 AC10A AC10H AK07A AK51B AK64A AL05A AL07A BA02 BA07 CA23A CC00B GB32 JA04A JA06A JA11A JK10 YY00A YY00B YY00H 4J002 BB052 BB213 BP021 DJ046 FB086 FB236 FD010 GN00 4J038 DG111 DG191 DG301 GA03 NA11 P07 NA08 NA23 NA23 NA23 NA08 NA23 NA23

Claims (3)

[Claims] 1. An injection-molded article obtained by injection-molding a propylene-based resin composition comprising the following components (a) to (d), the surface of the article being measured by ESCA (X-ray photoelectron spectroscopy) method: In the propylene-based resin injection-molded product having an oxygen atom / carbon atom abundance ratio of 0.008 or more, the coating film forming component is a component (e) a resin having a hydroxyl value of 50 to 90 KOHmg / g and a coating resin and a component. It is obtained by directly applying a polyurethane coating composition containing (f) an isocyanate compound and blended so that the ratio of the hydroxyl group equivalent of component (e) to the isocyanate group equivalent of component (f) is 5.0 or less. Painted parts. Component (a): crystalline propylene homopolymer portion 80 to 95
5% by weight and fractionation with o-dichlorobenzene
Propylene / ethylene block copolymer consisting of 5 to 20% by weight of ethylene / propylene random copolymerized portion represented as a component to be eluted at 0 ° C or lower 20 to 40% by weight Component (b): Melting point of 40 to 60 ° C Yes, and melt flow rate (230 ° C, 2.16kg) 0.5-1
5 g / 10 min ethylene-octene copolymer 20-4
0 wt% Component (c): Substantially the entire length is 15 μm or less, talc having an average particle size of 1 to 10 μm and an average aspect ratio of 3 or more 0 to 20 wt% Component (d): The hydroxyl group-containing maleic anhydride derivative represented by the formula is added to the propylene-based polymer in an amount of 3% of the total amount of the component (d).
The number average molecular weight grafted at a ratio of up to 20% by weight is 3,
2,000 to 15,000 modified propylene homopolymers or block or random copolymers of the same propylene and ethylene 20 to 40% by weight (In the formula, R represents an alkylene group having 1 to 4 carbon atoms.) 2. The component (e) has a hydroxyl value of 95 to 1
The coated part according to claim 1, which is obtained by applying a polyurethane coating composition, which is a mixture of a resin for 20 KOHmg / g active hydrogen-containing coating and a hydroxyl value of 20 to 45 KOHmg / g coating resin. 3. The component (e) is an acrylic polyol and / or a polyester polyol.
Or the coated part according to 2.