JPH0411643A - Polypropylene resin composition - Google Patents

Abstract

PURPOSE:To improve impact resistance and coatability by compounding a PP resin, a (rubber-modified) styrenic monomer-unsatd. dicarboxylic acid anhydride copolymer, and a specific diene-based hydrogenated block copolymer. CONSTITUTION:A copolymer comprising 5-30wt.% vinyl arom. polymer block and 95-70wt.% conjugated diene polymer block is hydrogenated to give a hydrogenated block copolymer wherein 20-80% of double bonds are hydrogenated. 60-90wt.% PP resin having an MI of 5g/10min or higher and a bending modulus of 10000kg/cm<2> or higher, 5-30wt.% (rubber-modified) styrenic monomer-unsatd. dicarboxylic acid anhydride copolymer, 5-25wt.% said hydrogenated block copolymer, and, if necessary, a lubricant, an antioxidant, a filler, a plasticizer, a pigment and dye, etc., are compounded and melt mixed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to automobile parts, particularly automobile bumper fenders.
The present invention relates to a polypropylene resin composition that can be suitably used as a member that requires high impact resistance and rigidity, as well as high surface hardness and good paintability.

[Prior art and problems to be solved by the invention] Since automobile parts such as automobile bumpers and fenders require a high degree of impact resistance, polypropylene blended with a large amount of EPR is generally used. .

However, this has the disadvantage of low surface hardness because it contains a large amount of rubber.

For this reason, materials to which an inorganic filler such as talc is further added are used.

Although this product has improved rigidity, there is no improvement in strength, and furthermore, there are problems such as poor weld appearance and flow marks.

To solve these problems, various compositions made of polypropylene, styrene resins, and styrene elastomers have been proposed (Japanese Patent Application Laid-Open No.
Publication No. 6-104978.

Publication No. 56-38338, Publication No. 64-9256,
(Special Publication No. 62-34782, etc.).

These things have some degree of impact resistance and rigidity.

Although it has an excellent appearance, it does not have extremely high impact resistance or advanced painting performance, and is not suitable for fields that require extremely high impact resistance or advanced painting performance, such as automobile bumpers. It could not be used.

[Means for Solving the Problems] Therefore, the present inventors conducted intensive research to solve these problems, and found that polypropylene resins, styrene resins with specific modifications, and double bond By blending a block copolymer of a vinyl-substituted aromatic compound saturated by hydrogenating a specific amount with a conjugated diene, it has high impact resistance and rigidity, as well as high surface hardness and advanced coating performance. It was discovered that a composition having the following properties can be obtained, and based on this finding, the present invention was completed.

That is, the present invention provides (A) polypropylene resin 60 to
90% by weight, (B) 5 to 30% by weight of a copolymer consisting of a styrenic monomer-unsaturated dicarboxylic anhydride, a rubber-modified copolymer of the copolymer, or a mixture thereof, and (C) vinyl A block copolymer consisting of a substituted aromatic compound polymer block and a conjugated diene polymer block, the block copolymer comprising 20 to 80% of the double bonds in the block copolymer.
is saturated with hydrogen, hydrogenated block copolymer 5~
A polypropylene resin composition comprising 25% by weight is provided.

The polypropylene resin used as component (A) in the present invention is not particularly limited as long as it is a crystalline polymer containing polypropylene resin, and may contain comonomers such as ethylene butene and 2-methylpentene-1.

This polypropylene resin has a melt index (Ml) of 5 g/10 minutes or more, preferably 7 g/10 min.
Minutes or more are used. If Ml is less than 5 g/10 minutes, moldability deteriorates, which is not preferable.

In addition, this polypropylene resin has a bending elastic modulus of 10,000 kg/cta or more, preferably 12.0
00kg/C111 or more is used.

The blending amount of the polypropylene resin in the present invention is as follows:
60-90% by weight of the total composition, preferably 65-80%
Weight%. If the amount of the polypropylene resin is less than 60 times the total composition, fluidity and rigidity may be insufficient, which is not preferable. On the other hand, if the amount of polypropylene resin exceeds 90% by weight of the entire composition, impact strength will be insufficient and sufficient paintability will not be obtained, which is not preferable.

Next, in the present invention, as component (B), a copolymer consisting of a styrene monomer and an unsaturated dicarboxylic anhydride, a rubber-modified copolymer of the copolymer, or a mixture thereof is used.

In addition to styrene, the styrene monomers in this copolymer of styrene monomer and unsaturated dicarboxylic acid anhydride include α-methylstyrene; 0-methylstyrene;
Examples include styrene derivatives such as m-methylstyrene; p-methylstyrene; 2,4-dichlorostyrene; 2°5-dichlorostyrene; dimethylstyrene; moreover,
In the present invention, some of these styrenic monomers are replaced with other monomers that can be copolymerized with methacrylic acid, methyl methacrylate, methyl acrylate, ethyl methacrylate, acrylonitrile, methacrylonitrile, and halogen-containing vinyl monomers. A substituted version can also be used.

In addition, as the unsaturated dicarboxylic anhydride in this copolymer consisting of a styrene monomer and an unsaturated dicarboxylic anhydride, maleic anhydride is particularly preferred, but in addition to this, itaconic anhydride, citraconic anhydride, Mesaconic acid, ethylmaleic anhydride, methylitaconic anhydride, chloromaleic anhydride, etc. can also be used.

The styrenic monomer-unsaturated dicarboxylic anhydride copolymer used as component (B) in the present invention is obtained by solution polymerization of the styrenic monomer and the unsaturated dicarboxylic anhydride. , bulk polymerization, bulk-suspension polymerization, and other known polymerization methods.

Furthermore, in the present invention, in addition to the above-mentioned copolymer consisting of a styrene monomer and unsaturated dicarboxylic acid anhydride, a copolymer obtained by rubber-modifying the above-mentioned copolymer can be used as the component (B). .

Examples of such a copolymer obtained by rubber-modifying the above-mentioned copolymer include a mixture of a copolymer of styrene monomer-unsaturated dicarboxylic acid anhydride as described above and a rubber component, Examples include those obtained by copolymerizing a monomer and an unsaturated dicarboxylic acid anhydride in the presence of a rubber component.

Rubber components used for this modification include synthetic rubbers such as polybutadiene rubber, butyl rubber, 2-styrene-butadiene rubber, styrene-methyl methacrylate-butadiene rubber, acrylonitrile rubber, and ethylene-propylene rubber, as well as natural rubber. can be mentioned.

Suitable examples of component (B) as described above include styrene-maleic anhydride copolymers and rubber-modified styrene-maleic anhydride copolymers.

The styrene-maleic anhydride copolymer preferably has a maleic anhydride content of 2 to 20 mol%,
Particularly preferred are those having a maleic anhydride content of 4 to 15 mol%. If the maleic anhydride content is less than 2 mol %, it is not preferable because the heat resistance will be poor. On the other hand, if the maleic anhydride content exceeds 20 mol %, this is not preferable because impact resistance decreases.

Further, the molecular weight of component (B) as described above is not particularly limited, but is preferably 100,000 to 300,000.

If it is less than 100,000, the impact resistance will be insufficient, while if it is more than 300,000, the fluidity will decrease, so both are not preferred.

The blending amount of component (B) in the present invention is 5% of the total composition.
-30% by weight, preferably 10-20% by weight. If the amount of component (B) is less than 5% by weight, the effect of improving rigidity will be small and sufficient coating strength will not be obtained. On the other hand, if the blending amount of component (B) exceeds 30% by weight, it is not preferable because the impact strength is insufficient and it is eluted into the cleaning solution (trichloroethane (TCE)) during coating, resulting in poor coating properties.

Furthermore, in the present invention, component (C) is a block copolymer consisting of a vinyl-substituted aromatic compound polymer block and a conjugated diene polymer block, the block copolymer having 20 to 80 double bonds in the block copolymer. A hydrogenated block copolymer in which % is saturated with hydrogen is used.

The hydrogenated block copolymer used as component (C) in the present invention basically consists of a polymer block A consisting of one or more vinyl-substituted aromatic compounds and one or more conjugated It consists of a polymer block B consisting of a diene.

Furthermore, this hydrogenated block copolymer is composed of the polymer block A and the polymer block B, and is one of the following (1) to (2).

(AB) + w (A represents the polymer block A, B represents the polymer block B.
represents an integer greater than or equal to 1 and less than or equal to 5. ), for example, B-A, B-A-B-A, B-A-B-A-B-A,
It is a hydrogenated block copolymer having a structure such as B-A-B-A-B-A-B-A.

Next, as for (2), a polymer block in which the polymer terminal always consists of a vinyl-substituted aromatic compound, for example, A-B-A
It is a hydrogenated block copolymer having a structure such as , A-B-A-B-A.

Finally, as for (■), polymer blocks whose polymer ends always consist of a conjugated diene compound, such as B-A-B, B-
It is a hydrogenated block copolymer having a structure such as A-B-A-B.

The vinyl-substituted aromatic compound constituting the polymer block A of the hydrogenated block copolymer as described above is preferably a styrene compound. Here, as a styrene compound,
Examples include styrene, α-methylstyrene, vinyltoluene, Ptert-butylstyrene, and the like, and these can be used alone or in combination of two or more. Among these, styrene is particularly preferred.

In addition, examples of the conjugated diene compound constituting the polymer block B of the hydrogenated block copolymer as described above include butadiene; isoprene; 1,3-pentadiene; 2,3-
Examples include dimethyl-1,3-butadiene, and these can be used alone or in combination of two or more.

A block copolymer consisting of a polymer block A as described above and a polymer block B as described above can be easily produced by a conventional method.

The method for producing these block copolymers before hydrogenation is as follows:
As long as it has the above-described structure, it may be obtained by any manufacturing method. Specifically, for example, a block copolymer as described above (vinyl-substituted aromatic compound-conjugated diene compound block copolymer) can be produced by carrying out a reaction in an inert solvent using a lithium catalyst or the like. Can be done (Special Public Interest Publication No. 40-23798
(see publication).

In the present invention, component (C) is a block copolymer as described above, and furthermore, a hydrogenated block copolymer in which 20 to 80% of the double bonds in the block copolymer are saturated with hydrogen. Use.

Such a hydrogenated block copolymer can be easily produced by hydrogenating the above-mentioned block copolymer according to a conventional method.

Such hydrogenated block copolymers (hydrogenated products) are disclosed in, for example, Japanese Patent Publications No. 42-8704 and Japanese Patent Publication No. 43-663.
It can be easily produced by the hydrogenation method described in Publication No. 6 and the like.

The hydrogenated block copolymer used as component (C) in the present invention has 20 to 20 double bonds in the block copolymer.
It is 80% saturated with hydrogen, preferably 30-70%.

Therefore, in producing the hydrogenated block copolymer, it is necessary to control the ratio so that the double bonds in the block copolymer are saturated by hydrogenation.

If the hydrogenation rate is less than 20%, the block copolymer will dissolve into a cleaning solution such as trichloroethane, resulting in poor coating properties, which is undesirable. On the other hand, if the hydrogenation rate exceeds 80%, , is not preferable because the impact strength of the composition is insufficient.

This hydrogenation rate of 20 to 80% may literally mean hydrogenation of 20 to 80% of the double bonds of the block copolymer, or hydrogenation of 100% of the double bonds or non-hydrogenation of the double bonds of the block copolymer. The average hydrogenation rate may be controlled at 20 to 80% by blending with other hydrogen.

Further, the amount of the vinyl-substituted aromatic compound which is a constituent unit of the block copolymer is preferably 5 to 30% by weight of the total. Here, the amount of vinyl substituted aromatic compound is 5%
If it is less than 30, the effect of improving compatibility is small;
If it exceeds the percentage by weight, not only will the effect of improving the impact resistance of the composition be small, but it will also dissolve into the cleaning solution during painting, resulting in poor paintability (
Therefore, both are undesirable.

The blending amount of component (C) in the present invention is 5% of the total composition.
-25% by weight, preferably 10-20% by weight. (
If the blending amount of component C) is less than 5% by weight, the impact strength of the composition will be insufficient, while if it exceeds 251% by weight, the rigidity of the composition will be insufficient and the composition will dissolve into the cleaning solution during painting. Both are unfavorable because they deteriorate paintability.

The polypropylene resin composition of the present invention is obtained by blending each of the above components in predetermined amounts.

Here, the polypropylene resin composition of the present invention may be produced according to a conventional method. For example, each component may be premixed using a mixer such as a Henschel mixer, tumbler blender kneader, etc., and then kneaded using an extruder. Alternatively, it may be produced by melt-kneading using a heating roll, a Banbury mixer, or the like.

Note that there is no particular restriction on the mixing and crossing order of each component, and the above (A) component, (B) component, and (C) component may be mixed simultaneously,
It may be kneaded, or after any two components are mixed and kneaded, the remaining one component may be mixed and kneaded therewith.

Furthermore, the polypropylene resin composition of the present invention can be appropriately blended with various commonly used additives, if desired.

Specifically, for example, stearic acid as a lubricant.

Behenic acid, zinc stearate, calcium stearate, magnesium stearate, ethylene bisstearamide, and the like can be used.

In addition, as an antioxidant, 2,6-di-t-butyl-4
-Methylphenol: Stearin-β (3,5-di-t
-butyl-4-hydroxyphenyl)propionate;
Hindered phenolic antioxidants such as triethylene glycol-bis-5-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate and tri(2
,4-di-t-butylphenyl) phosphite; 414
Phosphorous antioxidants such as "-butylidene bis(3-methyl-6-t-butylphenyl-di-tridecyl) phosphite can be used.

In addition, the polypropylene resin composition of the present invention includes:
Organic polysiloxane, mineral oil, etc., as well as ultraviolet absorbers, antistatic agents, fillers, plasticizers, and mold release agents.
Dyes etc. can be added.

〔Example] Next, the present invention will be explained in detail with reference to examples.

Examples 1 to 5 and Comparative Examples 1 to 7 After tri-blending each component in the proportions (wt%) shown in Table 1, a twin-screw kneader (manufactured by Toshiba Machine ■) was used.

TEM-35) at a temperature of 230°C to obtain pellets.

A test piece was made from the obtained pellet using an injection molding machine (Toshiba IS-90B, manufactured by Toshiba Machinery Co., Ltd.) at a set temperature of 230°C.

The obtained test piece was heated at 23°C and 50% humidity for 4 hours.
After adjusting the conditions for 8 hours, a test was conducted according to the following test method. The results are shown in Table 1.

・Izotsu impact strength...JIS K71
Compliant with 10/Bending characteristics...JI
Conforms to S K7203/Rockwell hardness...
・・Compliant with JIS K7202 Also, Example 1.2,
Using the pellets obtained in 4.5 and Comparative Examples 3 to 6,
The bumper was molded using a large injection molding machine (mold clamping force: 3.0 OOT).

Using the obtained bumper, an impact test (pendulum test) was conducted at -20°C or -30°C using a pendulum tester. The results are shown in Table 2.

The test conditions are as follows.

・Pendulum 2 Weight 1.200kg Speed 2.5m1
le/hr - Truck 2 Weight 1,440 kg Furthermore, using the bumper obtained above, the paintability was evaluated by the following method.

That is, the bumper obtained above was washed with trichloroethane (TCE) vapor for 30 seconds or 120 seconds, air-dried in the air for 30 minutes, and then subjected to surface activation treatment using plasma ions.

Thereafter, urethane paint was applied thereto and baked at 120°C for 30 minutes.

Regarding the sample bumper obtained in this way, 4
After conditioning at room temperature for 8 hours, a grain peel test of the coating film was conducted.

In addition, the sample bumper obtained in this way was
After being immersed in hot water at 0'C for 240 hours, it was taken out and air-dried, and the surface was observed for the presence or absence of blisters, and the coating film was subjected to a rough peel test in the same manner as above.

These results are shown in Table 2.

*1: Polypropylene resin a) = M I = 10, flexural modulus 16,000
kg/cmb)...MI-20, flexural modulus 1.40
0 kg/cflT*2: Polystyrene (MI=2. High impact polystyrene containing 6% by weight of butadiene)
*3: Styrene-maleic anhydride copolymer (HISMA
)C)...Unsaturated carboxylic acid content 14 mol%d)...
・Unsaturated carboxylic acid content 7 mol%*4: Ethylene-propylene rubber (propylene content 26% by weight, Mooney viscosity ML, 4.1°.・e.

*5: An elastomer made by hydrogenating a styrene-butadiene-styrene copolymer.
Styrene copolymer) *6: For Comparative Example 2, 10% by weight of talc was added.

From the results of the above Examples and Comparative Examples, the following points 1 to 2 can be found.

First, (2) Examples 1 to 5 and Comparative Examples 1.2 and 2 show that the products of the present invention have high surface hardness and an excellent balance between impact resistance and rigidity when compared with conventional EPR additives.

Next, from Comparative Example 3, the block copolymer of component (C) with an excessively high hydrogenation rate not only has low impact strength but also cannot be cleaned by melt cutting (TCE) because it uses polystyrene. It can be seen that styrene is eluted and the paintability is deteriorated.

Furthermore, from Comparative Example 5, it can be seen that when the hydrogenation rate of the block copolymer of component (C) is too low, the mechanical properties are high, but the paintability is low.

Furthermore, from ■Comparative Example 6, there was too much component (B), (
It can be seen that when the amounts of component A) and component (C) are small, the paintability is good, but the impact resistance is extremely low.

Finally, ■ From Comparative Example 7, the (B) component was too small and (
It can be seen that when the amount of component C) is too large, the bending physical properties 1 surface hardness is extremely low.

〔Effect of the invention〕

According to the polypropylene resin composition of the present invention, it is possible to obtain a material that maintains a high degree of balance between high impact strength and high rigidity, has high surface hardness, and has significantly improved paintability.

In particular, products obtained using the polypropylene resin composition of the present invention have significantly better paintability than conventional products, and have high painting performance that can withstand automotive painting lines.

Therefore, the polypropylene resin composition of the present invention
It can be suitably used in the production of automobile parts, particularly bumpers, fenders, and other members that require high impact resistance and rigidity, as well as high surface hardness and good paintability.

Patent applicant: Idemitsu Petrochemical Co., Ltd.

Claims (1)

[Claims] (A) 60-90% by weight of polypropylene resin, (B)
A copolymer consisting of a styrene monomer and an unsaturated dicarboxylic anhydride, a rubber-modified copolymer of the copolymer, or a mixture thereof in an amount of 5 to 30% by weight, and (C) a vinyl-substituted aromatic compound polymer block. A block copolymer consisting of a conjugated diene polymer block and a hydrogenated block copolymer in which 20 to 80% of the double bonds in the block copolymer are saturated with hydrogen, 5 to 25% by weight. A polypropylene resin composition consisting of.