JPH05320469A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition which has excellent moldability and can give a molding having good appearance, a particularly good balance between rigidity and impact resistance and markedly improved coatability. CONSTITUTION:This resin composition comprises 65-87.5wt.% crystalline ethylene/propylene block copolymer subjected to a molecular weight control treatment and having an MI of 15-70g/10min and an ethylene/propylene copolymer rubber having a propylene content of 25-55wt.% and a Mooney viscosity of 25-60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition suitable for the field of automobiles, particularly automobile parts mainly including bumpers, and home electric appliance housings to be coated. The resin composition of the present invention has excellent moldability, the appearance of the resulting molded article,
The present invention relates to a composition having a good balance of rigidity and impact resistance, and particularly having improved paintability.

[0002]

2. Description of the Related Art A great number of technologies relating to the resin composition of the present invention have been disclosed. For example, JP-A-53
-64257, JP-A-57-55952, JP-A-57-57952
44648, JP-A-57-207630, JP-A-58-58
17139, JP-A-58-111846, JP-A-58-
162652, JP-A-58-168648, JP-A-58
168649, JP-A-59-98157, JP-A-61
-43650, JP-A-63-172758, JP-A-2-
251547 and Japanese Patent Application Laid-Open No. 2-311533.

As is well known, since propylene and ethylene resins are non-polar, a surface treatment is carried out prior to coating or adhering the product. In particular, an epoch-making coating technology that uses TCE treatment and a chlorinated polyolefin-based primer has been developed and widely applied to the coating of polypropylene bumpers.
Taking the coating method used in automobile bumpers as an example, first, the bumper molded article is exposed to boiling 1,1,1-trichloroethane vapor (TCE treatment), and then the chlorinated polyolefin is dissolved in toluene. The step of spraying a primer solution containing the above solution as a main component on the surface to be coated (primer treatment), and then coating a urethane-based coating on it and heating and curing it.

On the other hand, researches have been made to eliminate the primer treatment itself, and there are some cases in which the material is polarized, the coating is improved (primerless coating), or plasma treatment is performed instead of the above-mentioned primer treatment. .. In addition, an attempt to develop a material that can be coated without TCE treatment is also disclosed. Most of them use ethylene / propylene rubber having a low Mooney viscosity. This is the case, for example, in JP-A-58-40341. This method is certainly effective in improving paintability, but it seems that improvement in impact strength is required for use in automobile bumpers. Further, ethylene / propylene rubbers having a propylene content of about 25 to 27% are used. For example, JP-A-57-44648 and JP-A-58
-40341 and JP-A-63-172758, it is said that a rubber having a high Mooney viscosity is suitable for improving impact strength and a rubber having a low Mooney viscosity is suitable for improving coatability, and the branch point thereof is Mooney viscosity. It is found that it is about 20 to 25. Further, in JP-A-57-44648, a combination of a rubber having a Mooney viscosity of 18 to 34 and a polypropylene having an MI of 10 or less is used to provide a balance between both. In addition, JP-A-63-172
In Japanese Patent No. 758, an ethylene / propylene rubber having a propylene content of 45 to 50% by weight is used, and as its effect, improvement of impact resistance by improving dispersibility and improvement of product appearance by using a silane-treated filler are taken up. ing.

As described above, as the bumpers of automobiles are made of resin, weight reduction is required in order to further improve fuel efficiency, and polypropylene-based materials have been developed to meet the demand. That is, polypropylene bumper materials are required to have good moldability, appearance of molded articles, good balance of rigidity and impact resistance, and excellent paintability, and corresponding materials have been developed and studied.

[0006]

The present invention is also based on the above-mentioned object, but another object is the above-mentioned T
Another object of the present invention is to provide a composition having excellent adhesion to a primer and adhesion to a primerless paint without CE treatment. One of the important challenges in the recent automotive field is to find alternatives to certain CFCs or trichloroethanes, which are said to destroy the ozone layer, or a way to avoid them.

In the bumper coating process, the effect of TCE treatment is to remove the fragile layer (generally referred to as WBL) on the surface of the material, or to remove rubber on the surface, in addition to removing the deposits on the surface. It is known that by etching, by further penetrating the surface of the material and expanding it to widen the molecular gap, it greatly contributes to the improvement of the adhesion with the primer and the adhesion with the primerless paint. Therefore, it is a major problem in this field to develop a polypropylene-based material having high adhesion to a primer and high adhesion to a primerless paint without this TCE treatment, and is also one of the objects of the present invention. However, with the polypropylene and ethylene / propylene rubber-based composition, as described above, it is not possible to obtain a composition in which the moldability of the composition, the appearance of the molded product, the strength and paintability of the product, and the adhesion strength of the coating film are balanced. It's quite difficult. Even if it can be put to practical use in parts for which the required characteristics of coating adhesion strength are milder than those of automobile parts, it is still necessary to improve parts such as automobile bumper parts that require severe coating performance. In particular, in order to deal with a large-sized molded product in which a bumper and a face are integrated, a composition having high fluidity is required.

The inventors of the present invention have balanced the moldability of the composition, the appearance of the molded product, the strength and paintability of the product, and the adhesion strength of the coating film with respect to this type of polypropylene and ethylene / propylene rubber composition. As a result of intensive research to develop a product, as a result of a composition comprising a specific polypropylene subjected to a specific molecular weight control treatment (CR treatment) and a specific ethylene / propylene rubber, and optionally a combination with an inorganic filler. The present invention has been found to be suitable for the purpose, and has led to the present invention.

[0009]

That is, the present invention comprises a mixture of the following components a and b, wherein the ratio of each component is a) 65-87.5% by weight, b) 35-12.5% by weight. %
It is a resin composition characterized by being. a) A crystalline ethylene / propylene block copolymer that has been subjected to a molecular weight adjustment treatment and has a melt flow index of 15 to 70 g / 10 min.

B) An ethylene / propylene copolymer rubber having a propylene content of 25 to 55% by weight and a Mooney viscosity of 25 to 60. Further, preferably, the above-mentioned resin composition in which the crystalline ethylene / propylene block copolymer of a) has a degree of molecular weight control of 1.5 to 50. Furthermore, the ethylene content of the molecular weight adjustment treatment is 5 to 20.
% By weight, salt flow index 1 to 20 g / 10
The above-mentioned resin composition is a crystalline ethylene / propylene block copolymer of min, the molecular weight of which is adjusted using an organic peroxide.

The melt flow index of each physical property value is ASTM D1238 (230 ° C.,
2.16 kg), Mooney viscosity is JIS K6
The value is based on 300 (ML1 + 4, 100 ° C.). The degree of molecular weight regulation (CR degree) is (MI after CR treatment).
(Value) divided by (MI value before CR processing).

The crystalline ethylene / propylene block copolymer which can be used in the present invention is subjected to CR treatment,
Its melt flow index (MI) is 15-70 g
It is a crystalline ethylene / propylene block copolymer of / 10 min. Further, the crystalline ethylene / propylene block copolymer preferably has a CR degree of 1.5 to 5
It is 0. The CR treatment in the present invention is a treatment for intentionally breaking the molecular chain of a crystalline ethylene / propylene block copolymer (hereinafter abbreviated as polypropylene block copolymer) to obtain a polypropylene block copolymer having a lower molecular weight. Say. As a general method, there is a method of mechanically kneading at a high shear rate at a melting temperature, or a method of adding an organic peroxide and kneading at a temperature higher than the decomposition temperature. The method using an organic peroxide makes it possible to obtain a product having a uniform molecular weight distribution at a relatively low temperature, with good efficiency. Further, although the reason is not clear, the coating property is better when the CR treatment is performed using an organic peroxide.

As an example of the organic peroxide used in the CR treatment of the present invention, a dialkyl peroxide having a half-life temperature of 1 minute to 170 to 200 ° C. is preferably used. For example, dicumyl peroxide, 2,5-dimethyl-2,
5-di (tert-butylperoxy) hexane,
2,5-Dimethyl-2,5-di (tert-butylperoxy) hexyne-3,1,3-bis (tertiary-)
Butyl peroxy-isoprovir) benzene and the like. However, the type of the organic peroxide itself is not important here, and it is important to obtain a polypropylene block copolymer having a uniform molecular weight distribution obtained by CR treatment. Therefore, it is not necessarily limited to the dialkyl peroxide type.

Moldability as a polypropylene bumper part is described in JP-A-58-111846 and JP-A-58-168.
As described in Japanese Patent Publication No. 648 and the like, polypropylene block copolymers having a high MI have come to be preferably used, but those having a low MI are preferable in view of their physical properties. This is because the polypropylene block copolymer having a higher MI has more low molecular weight substances which form WBL in the molecular weight distribution, which is a problem during coating. It is less in high molecular weight polypropylene block copolymers. In the present invention, a CR-treated polypropylene block copolymer is used as a useful method capable of achieving both of them. That is, when the CR treatment is performed using an organic peroxide, the molecular chain of high molecular weight polypropylene is preferentially cut. This makes it possible to obtain a polypropylene block copolymer having a small amount of low molecular weight substances and a uniform MI, and a high MI. This can be very effectively utilized even when coating is carried out without TCE treatment.
However, if the CR degree is raised too much, the whole molecular weight becomes low, and as a result, the impact resistance and the tensile elongation are lowered.

The MI of the CR-treated polypropylene block copolymer used in the present invention is 15 to 70 g / 10 min, more preferably 20 to 50 g / 10 min. The preferred CR-treated polypropylene block copolymer has an ethylene content of 5 to 20% by weight and an MI of 1.0 to.
20 g / 10 min, more preferably 1.5 to 20 g
It was obtained by CR treatment of a crystalline ethylene / propylene block copolymer of / 10 min. The CR degree at this time is 1.5 to 50, and more preferably 1.
5 to 20. In the case of a CR-treated polypropylene using a base having a relatively high MI, it is preferable that the CR degree is low.

The ethylene content of the base polypropylene block copolymer is preferably 5 to 20% by weight,
More preferably, it is 5 to 15% by weight. The ethylene content improves the dispersibility when mixing the second component rubber,
It also contributes to impact resistance, and if it is too large, the copolymerized portion forming a domain during CR treatment is crosslinked to deteriorate the appearance, or the product rigidity becomes too low. In addition to this, as a feature of using a CR-treated polypropylene block copolymer,
Warpage of molded products can be reduced.

Further, in the present invention, as a method for controlling the MI of the composition, a CR-treated polypropylene block copolymer and an untreated low-MI polypropylene block copolymer can be combined. The amount of untreated low MI polypropylene that can be mixed in such a case is not limited to a certain amount, but is 50% by weight or less. In addition, when a propylene homopolymer or an ethylene / propylene random copolymer is used as the base of the above-mentioned component a, the resulting molded article is inferior in impact strength at low temperature, which is not preferable.

Next, the ethylene / propylene copolymer rubber having a propylene content of 25 to 55% by weight and a Mooney viscosity of 25 to 60 used in the present invention will be described. The propylene content and Mooney viscosity of ethylene / propylene rubber (hereinafter abbreviated as EPR) are important factors along with the CR treatment of the polypropylene block copolymer, which determines the physical properties and paintability of the obtained product. That is,
The propylene content of EPR has a great influence on the paintability and impact strength of the physical properties of the product. In the present invention, 25 to 55% by weight, preferably 30 to 50% by weight is used. EPR having a propylene content in this category has the lowest crystallinity and the highest impact strength.

Next, the Mooney viscosity of EPR is 25 to 60,
More preferably, those of 30 to 50 are used. In the prior art, those having a low Mooney viscosity are preferably used for the purpose of improving coatability, but they are not preferable for impact strength. In the present invention, it has been found that in the opposite direction, this problem can be solved by combining it with a CR-treated polypropylene block copolymer if the EPR has a specific propylene content. Furthermore, this has made it possible to utilize a more preferred EPR for impact strength. However, such an EPR
Both forms are usually sold as veils.
The reason is that those having a propylene content of about 30 to 50% by weight are soft and have self-adhesiveness, so that they are easily blocked even in the form of pellets, and therefore cannot be transported or stored. Further, a machine for rubber processing such as a Banbury mixer is required for directly kneading and continuously processing such a bale with polypropylene. This can be processed with a uniaxial or biaxial screw type extrusion kneading continuous machine for plastic processing, and in order to disperse easily, it is industrially necessary to process rubber into pellets called master pellets in advance. It is also useful in the present invention and is preferably used in the present invention. In this case, the amount of EPR in the master pellet was 65 to 75% by weight, and the remaining 3
5 to 25% by weight is polypropylene or polyethylene. Particularly, in the present invention, it is possible to obtain the EPR having excellent physical properties and coating properties by using the EPR previously kneaded with polypropylene or polyethylene.

The essential components of the present invention are the CR-treated polypropylene block copolymer as the component a and the EPR as the component b, and the ratio of the components is 65 to 8 for a.
It is 7.5% by weight and b is 35 to 12.5% by weight. If the rubber content is larger than this, the product rigidity will be low, and a molded product such as a large bumper having a heavy weight will be deformed depending on the heating and drying temperature during coating, which is not preferable. On the other hand, if the rubber content is low, generally known drawbacks such as impact strength and adhesion of the coating film deteriorate. Therefore, preferably a is 70
˜87.5% by weight, b is 30 to 12.5% by weight, most preferably a is 75 to 85% by weight and b is 25 to 15% by weight.

In the present invention, the average particle size is 0.5 to
If necessary, up to 40% by weight of a plate-to-granular inorganic filler having a particle diameter of 10μ and / or a fibrous inorganic filler having a fiber diameter of 0.5-1.5μ may be added to 100% by weight of the total amount of components a and b. Can be mixed. The purpose of mixing this filler is to control the shrinkage rate during molding, or control the linear expansion rate. As the granular to plate-like inorganic filler,
The average particle size of calcium carbonate, talc, mica and the like is preferably 0.5 to 10 μm, particularly preferably 0.8 to 5 μm. As the fibrous inorganic filler, magnesium oxysulfate, calcium silicate, glass fiber or the like having an average particle diameter of 0.5 to 1.5 μ, preferably an aspect ratio of 20 to
150. Further, those obtained by surface-treating these fillers with a silane coupling agent or methacrylic acid are also suitably used. Further, in order to improve the dispersion of the inorganic filler in the composition, it is effective to add about 1 to 3% of metal soap to the filler at the time of compounding.
In addition to these, well-known light stabilizers and heat stabilizers for polyolefin resins can be added to the composition of the present invention depending on the purpose.

When the molded article of the composition of the present invention is coated, the TCE treatment which is conventionally performed as a pretreatment is not particularly required. That is, if the molded product is free from general coating obstacles such as dust, dust, and oil adhesion, normal coating can be performed by directly applying a primer such as a chlorinated polyolefin-based primer. As the primer, a known chlorinated polyolefin-based primer having a chlorine content of 15 to 35% as a main component, a chlorinated polyolefin and a basic nitrogen-containing acrylic copolymer made of an epoxy resin, an unsaturated carboxylic acid or an anhydride thereof is used. A primer made of a chlorinated polyolefin modified with a substance, a primer made of a copolymer of a chlorinated polyolefin and an esterified unsaturated carboxylic acid, and the like are suitable. In addition, paints using these as binders can also be applied directly.

[0023]

EXAMPLES Prior to the examples and comparative examples of the present invention, crystalline ethylene / propylene block copolymer (hereinafter abbreviated as polypropylene block copolymer) was prepared in advance.
The CR treatment and the EPR masterbatch were performed. This is collectively described below as a production example.

Regarding each physical property and its measuring method,
It is as follows. MI is ASTM D1238 (23
0 ° C., 2.16 kg), FM is the flexural modulus of ASTM D790, TE is the tensile elongation at break of ASTM D638,
Izod is impact strength according to ASTM D256, Mw
/ Mn (used as an index of the molecular weight distribution of polypropylene) is the value measured by the GPC method, and the Mooney viscosity is JIS K6300 (ML1 + 4, value at 100 ° C.).

In the coating property evaluation test, the composition of the present invention was used in an injection molding machine at 150 × 150 × 3t.
Was molded into a test piece. The coating method is JIS / K
5400-3.5 (2) Spray coating, appearance as a method for evaluating coated products is the same as above 3.7 Evaluation standard for coating film (Japan Paint Inspection Association "Evaluation standard for coating film"), 6.15
Cross-cut test, the same, 7.3 boiling water resistance, and JIS D0
202-4.7 Moisture resistance test, 4.10 Gasoline resistance test.

[0026]

Production Example 1 (1) A crystalline polypropylene block copolymer having an ethylene content of 12% by weight and an MI of 3 g / 10 min (hereinafter referred to as polymerized PP-1) was added with 1.3-bis (tertiary-butyl). Peroxyisopropyl) benzene was added, and a CR process was performed by extruding at 250 ° C. using a uniaxial extruder with a 90φ vent having an L / D of 32. The three types of CR-treated polypropylene block copolymers obtained were designated as PCR-11, PCR-12, and PCR-13,
The properties are also shown in Table 1.

(2) Ethylene content 9% by weight, MI 8
2.5-Dimethyl-2.5-di (tertiary-butylperoxy) hexane was added to a crystalline polypropylene block copolymer (hereinafter, referred to as polymerized PP-2) of g / 10 min, and the above (1 CR processing was performed similarly to the above.
The two types of CR-treated polypropylene block copolymers thus obtained were designated as PCR-21 and PCR-22, and their properties are also shown in Table 1.

(3) In addition to this, in Table 1, in addition to the polymerized PP-1 and polymerized PP-2 used as the base of the CR treatment described in (1) and (2) of Production Example 1, the same polymerized Ethylene content 9% by weight, MI 20 and M
A polypropylene block copolymer having an I of 40 g / 10 min was designated as polymerized PP-3 and 4, and the characteristics of the polymer were also described.

As shown in the above production examples, the polypropylene block copolymer is subjected to CR treatment so that it has a higher MI value than the polypropylene block copolymer directly obtained in the original polymerization and has a molecular weight distribution (Mw / Mw / M
n) is sharp.

[0030]

Production Example 2 EPR-1 to EPR-6 (Group A) of the present invention
And EPR-7 to EPR12 (B used as a comparison
Table 2 shows the Mooney viscosity, the propylene content (% by weight), and the shape of the rubber of each group. For the veil-shaped rubber, 70% by weight of the rubber, 30% by weight of PCR-1 obtained in the above Production Example 1 and a small amount of a stabilizer for preventing thermal deterioration during kneading of both were added. After kneading with a Banbury kneader at 220 ° C. for 2 minutes, the rubber master pellets were processed.

[0031]

Example 1 PCR-21 and EPR-1 to EPR-6 (master pellets used for EPR-1 to EPR-5) obtained by the above-described production example were converted into pure PP / pure EPR (value by weight). = 75/25, and 0.2% by weight of antioxidant were weighed and pre-mixed using a Henschel mixer. This mixture was kneaded at a preset temperature of 200 ° C. using a twin-screw kneading extruder to be pelletized.

The pellets thus obtained were subjected to an Izod impact test piece and a coating test 1 using an injection molding machine.
A plate-like test piece having a thickness of 50 × 75 × 3 mm was prepared. The surface of the coated test piece was wiped with isopropyl alcohol (abbreviated to iPrOH). Next, an acid-modified polyolefin-based primer (Soflex 6000; trade name of Kansai Paint Co., Ltd.) was sprayed to a dry coating thickness of about 10 μm, and a drying treatment was performed at 100 ° C. for 20 minutes. Furthermore, a two-component urethane paint (Campet-Retan PG60) is spray-painted to a thickness of about 50μ in dry film conversion, and then 8
The mixture was heat-treated at 0 ° C. for 35 minutes and left at room temperature for 1 week. The Izod impact test values and the coated products were evaluated for durability and peeling strength of the coating film. Durability is JI
Cycle cracking test according to S ・ D0202 (4.17), evaluation method of peeling strength of coating film and its value are as follows. It is the strength when it is reinforced and peeled together with the coating film in the direction of 180 degrees at a speed of 50 mm / min. The results are shown in Table 3.

[0033]

Comparative Example 1 Polymerized PP-3 having the same MI and the same ethylene content as PCR-21 was used, and EPR-7 to EP were also used.
PP / EPR = 75/25 using R-12 pellets
A mixture of 10% by weight and 0.2% by weight of an antioxidant was kneaded in the same manner as in Example 1 to obtain pellets. This pellet was used as a plate-like test piece as in Example 1, and the same physical property test and evaluation test as in Example 1 were performed. The results are shown in Table 3.

[0034]

Example 2 Using the master pellets of PCR-11 and EPR-3, the ratio of pure PP / pure EPR shown in Table 4 was 65/35 to 85/15 (wt%) and antioxidant 0.2.
Weight percent was weighed and mixed. Using a twin-screw kneading extruder, this was kneaded at a set temperature of 200 ° C to form pellets. Each of these was injection-molded into a bending test piece, an Izod impact test piece, and a plate-like test piece of 150 × 75 × 3 mm thickness for evaluating coatability. Each of the paintability test pieces was ultrasonically washed with a 0.4% neutral detergent aqueous solution at 50 ° C. for 60 seconds, then washed with water and dried to obtain an epoxy-modified chlorinated polyolefin to have a thickness of about 15 μm in terms of dry film. A system primer (RB291 two-component type; product of Nippon Bee Chemical Co., Ltd.) was sprayed. Further, a two-component urethane paint (Campe-Retan PG60) was spray-painted so as to have a thickness of about 50 μm in terms of dry film, then heat-treated at 80 ° C. for 35 min and left at room temperature for 1 week. The results of various evaluation tests for this coated product are shown in Table 4. Flexural modulus (FM) and Izod impact test values, peeling strength of coating film, solvent resistance (150 × 75 × 3 mm thick plate-shaped test piece immersed in gasoline at 20 to 25 ° C. for 24 hours The appearance is also shown in Table 4).

[0035]

[Comparative Examples 2 and 3] The ratio of pure PP / pure EPR was 60 /
A plate-like test piece was prepared in the same manner as in Example 2 except that the values were changed to 40 (Comparative Example 2) and 90/10 (Comparative Example 3), and a physical property test and an evaluation test were performed. The results are shown in Table 4.

[0036]

Example 3 PCR-22 and PCR-11 were used in combination and E
PR-2 shown in Table 5 is pure PP / pure EPR = 75/25
Talc (Microace P3; trade name of Nippon Talc Co., Ltd.) with an antioxidant and a light stabilizer of 0.2% by weight, respectively, and an average particle size of about 1.7μ. ) Was blended in the amounts shown in Table 5 and kneaded in the same manner as in Example 1 to form pellets. This product was injection-molded to make test pieces for each purpose, and various physical property tests and coating film evaluation tests were carried out. The results are collectively shown in Table 5. Therefore, if the talc as described above is used as a filler in the composition of the present invention, 4
It was revealed that the total balance did not collapse even if it was put up to about 0 copies.

[0037]

Example 4, Comparative Example 4 and Reference Example 1 POR-21 / EPR-3 = 80/20 as Example 4, polymerized PP-3 / EPR-8 = 80/20 (% by weight) as Comparative Example 4,
Further, 0.2 wt% of each of the antioxidant and the light stabilizer was kneaded in the same manner as in Example 1 and pelletized. Each of these is injection molded and 150 × 75 × 3mm
A thick plate-shaped test piece was used. This test piece is
Ultrasonic cleaning was performed in H at 35 ° C. for 60 seconds. For the sample of Example 4, 4% of phosphoric acid type detergent (product of Tosoh Corp.) ID-112, 1% in 50 ° C. aqueous solution was used.
Minute wash and 1% of ID-113, 3 in 50 ° C aqueous solution
After washing for 0 seconds, it was washed with water and dried. In addition, as Reference Example 1, when 1,1,1-trichloroethane was added to the steam under boiling,
A test piece which was exposed for 0 seconds and washed was prepared. A modified polyolefin-based primer (S112 primer; manufactured by Nagashima Special Coating Co., Ltd.) was sprayed onto this product to a thickness of about 15 μm in terms of dry film, and the mixture was allowed to stand at room temperature for 30 minutes. Then, two-component polyester / urethane-based paint (R263 / R27
1; Nippon Bee Chemical Co., Ltd. product) is spray-coated to a dry coating thickness of about 50 μm, and then 12
It was heat-treated at 0 ° C. for 30 minutes and left for 1 week. The results of various evaluation tests performed on this coated product are also shown in Table 6. From the above results, the invention products showed almost the same coating performance as the TCE treatment even when washed with iPrOH or detergent.

[0038]

[Comparative Example 5] For the purpose of observing the difference in effect between the bale-shaped EPR and the EPR pre-master pelletized, the EPR-2 of the material of PP / EPR / talc = 75/25/5 ratio shown in Example 3 was used. Instead of the master pellet, the original bale-shaped EPR-2 was roughly crushed with a bale cutter, crushed with a freeze crusher into 2 to 7 mm, and sprinkled with talc to prevent blocking. Pellets were obtained by kneading with the same formulation and method as in Example 3 except that this was used. When the physical properties of this product were measured by the same measurement method, specific gravity, M
I and FM were almost the same, but TE was 120-350
% And Izod were as low as 7 to 10, and the variations were large.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

[Table 6]

[0045]

EFFECTS OF THE INVENTION The resin composition of the present invention is excellent in adhesion to a primer and adhesion to a primerless paint even without TCE treatment. Further, this composition has excellent moldability, and the resulting molded article has a good balance of appearance, rigidity and impact resistance. Further, it is possible to obtain a paint having a good balance of paintability and coating film adhesion strength. The resin composition is useful in the field of automobiles, particularly automobile parts mainly including bumpers, and home electric appliance housings to be coated.

Claims (3)

[Claims] 1. A mixture of the following components a and b, wherein the ratio of each component is a / b = 65/35 to 87.5 / 1.
The resin composition is 2.5 (% by weight). a) A crystalline ethylene / propylene block copolymer that has been subjected to a molecular weight adjustment treatment and has a melt flow index of 15 to 70 g / 10 min. b) An ethylene / propylene copolymer rubber having a propylene content of 25 to 55% by weight and a Mooney viscosity of 25 to 60. 2. The crystalline ethylene / propylene block copolymer having a degree of molecular weight control of 1.5 to 50.
Resin composition. 3. The molecular weight control treatment is performed so that the ethylene content is 5
~ 20 wt%, melt flow index 1-20g
A crystalline ethylene / propylene block copolymer of / 10 min, the molecular weight of which is adjusted using an organic peroxide, and the degree of molecular weight adjustment is 1.5 to 50. 1. The resin composition of 1.