JPH0635542B2 - Polyamide composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyamide resin composition obtained by blending a polyamide resin with a specific modified copolymer and an organic peroxide. More specifically, a poorly compatible polyamide resin and the modified copolymer are uniformly compatible with an organic peroxide to improve the drawbacks of both resins and have excellent heat resistance, chemical resistance, impact resistance, etc. Another object of the present invention is to provide a resin composition which has excellent mechanical properties as well as a molded article which is particularly excellent in whitening resistance.

[Conventional technology]

Conventionally, many attempts have been made to solve the drawbacks of each thermoplastic resin by blending thermoplastic resins having different properties. However, heterogeneous polymers usually have poor compatibility and have the drawback that their mechanical properties tend to deteriorate below those of a single polymer. On the other hand, blends of highly compatible polymers are also similar in nature and, therefore, one cannot usually expect characteristic properties.

In recent years, in order to uniformly disperse polymers having different properties that are difficult to be compatible with each other, various modifications of the polymer have been studied, for example, a composition part in which a modified olefin rubber is finely dispersed in polyamide matrix is improved in flexibility and resistance. It has been found to exhibit impact resistance (Japanese Patent Laid-Open No. 51-143061).

[Problems to be solved by the invention]

In the present invention, when the conventional composition is molded and used, if a large distortion is applied to the molded product, the part thereof is whitened and a partial phase separation occurs, resulting in a remarkable deterioration of the property as a flexible material. The problem is solved.

[Means for solving problems]

The present inventors have earnestly aimed at solving the above-mentioned problems, namely, to obtain a polyamide resin composition which gives a molded article having excellent whitening resistance in addition to properties such as heat resistance, chemical resistance, and impact resistance. As a result of the research, the present invention has been completed. That is, the present invention is a polyamide (A), a modified copolymer (B)
And an organic peroxide (C), and the modified copolymer (B) is a copolymer of a vinyl aromatic compound and a conjugated diene compound and / or an unsaturated carboxylic acid in a part or all of its hydride. Alternatively, a polyamide resin composition obtained by graft-copolymerizing a derivative thereof, wherein the amount of the organic peroxide (C) is 0.01 to 2.5% by weight based on the total amount of (A) and (B).

The polyamide used as the component (A) in the present invention is obtained by polycondensation of diamine and dicarboxylic acid, self-condensation of ω-amino acid, ring-opening polymerization of lactams, and has a molecular weight sufficient to produce a molded article. It is a thing. Specifically, polyhexamethylene adipamide, polyhexamethylene azamide, polyhexamethylene sebacamide, polyhexamethylene dodecanoamide, polybis (4-aminocyclohexyl) methandodecanoamide, polycaprolactam, polylauritzlactam. , Poly-11-aminoundecanoic acid, metaxylylene adipamide, or copolymers thereof.

Next, the modified copolymer (B) to be blended with the polyamide (A),
It is a copolymer of a vinyl aromatic compound and a conjugated diene compound and / or a hydride thereof, which is partially or wholly graft-copolymerized with an unsaturated carboxylic acid or a derivative thereof.

The above-mentioned copolymer comprising a vinyl aromatic compound and a conjugated diene compound and / or its hydride includes a random copolymer comprising a vinyl aromatic compound and a conjugated diene compound, linear, radial or branched. Block copolymers, and particularly preferably hydrogenated hydrides thereof are mentioned. Vinyl aromatic compounds include styrene,
α-methylstyrene, vinyltoluene, p-tert-butylstyrene, vinylxylene, ethylvinylxylene,
Examples are vinylnaphthalene and mixtures thereof, of which styrene is particularly preferred. The conjugated diene compound includes 1,3-butadiene, isoprene,
1,3-pentadiene, 2,3-dimethylbutadiene,
Examples thereof include halogenated derivatives and mixtures thereof. Among these, butadiene or a combination of conjugated diene compounds mainly containing butadiene is preferable, and butadiene is particularly preferable.

Among the copolymers composed of a vinyl aromatic compound and a conjugated diene compound, the random copolymer has a number average molecular weight of about 10,000 to about 1,000,000, and preferably about 20,000 to about 300,000. Block copolymers include, for example, JP-A-52-150.
There are block copolymers disclosed in JP-A-53-71158 and JP-A-53-71158, in which blocks (X) and (X ¹ ) composed of a vinyl aromatic compound and a block (Y) composed of a conjugated diene compound (where X and X ¹ may be the same or different), but having a structure such as XY-X ¹ , XY, or further (N is an integer of 1 to 10) and the like can also be mentioned. Of these block copolymers, the terminal block is preferably a block made of a vinyl aromatic compound. The number average molecular weight of the block copolymer is preferably in the range of about 10,000 to about 1,000,000, particularly preferably about 20,000 to about 300,000.
Also, the average molecular weight of each of the vinyl aromatic compound blocks is preferably about 1,000 to about 5,000.
00, particularly preferably about 2000 to about 30,000
And the average molecular weight of each block of conjugated diene compounds is preferably from about 1000 to about 500.
000, particularly preferably about 2000 to about 3000
The range is 00.

The weight ratio of the vinyl aromatic compound to the conjugated diene compound in these random and block copolymers is preferably in the range of about 2/98 to about 60/40, particularly preferably about 10/90 to about 40/60. is there.

In the present invention, hydrides obtained by hydrogenating these copolymers are preferably used.

When hydrogenating a copolymer of a vinyl aromatic compound and a conjugated diene compound, it is preferable that 90% or more of the aliphatic double bonds are hydrogenated and 10% or less of the aromatic double bonds are hydrogenated. It is preferable that 99% or more of the aliphatic double bonds are hydrogenated and 5% or less of the aromatic double bonds are hydrogenated.

Hydrogenation can be carried out by any conventionally known method.

As the copolymer composed of a vinyl aromatic compound and a conjugated diene compound, specifically, a styrene-butadiene random copolymer, a styrene-isoprene random copolymer, a butadiene-polystyrene-block copolymer, a polystyrene-polyisoprene-polystyrene. -Block copolymers, poly (α-methylstyrene) -polybutadiene-poly (α-methylstyrene) -block copolymers, and the like, and more preferably hydrides thereof. As these copolymers, those commercially available under the trade names of Califlex, Kraton, Sorprene and the like can be used.

To graft-copolymerize a graft monomer selected from an unsaturated carboxylic acid and its derivative onto a copolymer composed of a vinyl aromatic compound and a conjugated diene compound and / or its hydride, the copolymer and the graft monomer should be , In the melt or solution, with or without a radical initiator.

Graft monomers selected from unsaturated carboxylic acids and their derivatives include acrylic acid, methacrylic acid, α-
Ethyl acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, endo-bicyclo (2,2,1) hept-5-ene-2,3-dicarboxylic acid (naphthic acid ), Unsaturated carboxylic acids such as methyl-endocis-bicyclo (2,2,1) hept-5-ene-2,3-dicarboxylic acid (methylnaphthic acid), their acid halides, amides, imides, acid anhydrides, Examples thereof include derivatives such as esters, and specific examples include maleenyl chloride, maleimide,
Examples include maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like. Among these, unsaturated dicarboxylic acids or acid anhydrides thereof are preferable, and maleic acid, nadic acid or their acid anhydrides are particularly preferable.

The method for graft-copolymerizing the graft monomer with the copolymer is not particularly limited, but the modified copolymer obtained may contain unfavorable components such as gel, or the fluidity thereof may decrease. It is desirable to avoid deterioration of workability. For this purpose, when the graft copolymerization is carried out by an addition reaction under melt mixing conditions using an extruder or the like, it is carried out in the presence of a known stabilizer such as a phenol type, phosphorus type or amine type stabilizer. Is desirable.

The reaction temperature for the graft copolymerization is usually about 60 to about 35.
It is carried out at 0 ° C., particularly preferably at about 100 to about 300 ° C. The addition ratio of the grafting monomer is preferably about 0.001 to about 20 parts by weight, especially 00.1 to 10% by weight, based on 100 parts by weight of the block copolymer, and the addition ratio of the radical initiator is preferably 0.001 to about 20% by weight. It is preferably 30% by weight, and particularly preferably 0.01 to 20 parts by weight. By graft-copolymerizing within such a range, the graft monomer can be efficiently grafted onto the copolymer.

The modified copolymer prepared by the above-mentioned method removes by-products such as gels if necessary, or a copolymer composed of a vinyl aromatic compound and a conjugated diene compound and / or its hydride. Prepared by diluting.

The modified copolymer used in the present invention is the copolymer 100
The proportion of grafting monomer is about 0.001 to about 20 parts by weight, and particularly preferably about 0.01 to about 1 part by weight.
It is in the range of 0 parts by weight. If it is less than 0.001 part by weight, the effect of improving the physical properties is small, and if it exceeds 20 parts by weight, gelation tends to occur during synthesis.

The mixing ratio of the resin in the composition of the present invention is a polyamide resin.
(A) 95 to 5% by weight, preferably 90 to 40% by weight, modified copolymer (B) 5 to 95% by weight, preferably 10 to 60%
% By weight.

In the present invention, an organic peroxide (C) is blended in addition to the polyamide resin (A) and the modified copolymer (B). Examples of such organic peroxides include benzol peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide and the like.

The amount of the organic peroxide (C) used is (A) and
0.01-2.5 wt% relative to the total amount of (B), preferably 0.1
~ 1.0% by weight.

In preparing the resin composition of the present invention, the above-mentioned components (A), (B) and (C) are usually melt-kneaded. For example, each component is mixed in a suitable form such as granules or powder with a V-type blender, a Henschel mixer, a super mixer, etc., and this is directly molded, or melt-mixed with an extruder, kneader, etc. to form a chip. This may be molded.

The composition of the present invention contains, in addition to the above-mentioned three essential components, an antioxidant, an ultraviolet absorber, a photoprotective agent, a phosphite stabilizer, a peroxide dispersant, a basic auxiliary agent, if necessary. Compounding fillers such as nucleating agents, plasticizers, lubricants, antistatic agents, flame retardants, pigments, dyes, carbov black, asbestos, glass fiber, potassium whisker titanate, mica, kaolin, talc, silica, and silica alumina. It is also possible.

Some elastomers and rubbers show good compatibility with polyamide resins when added in a relatively small amount, but when added in a large amount the compatibility deteriorates and phase separation is observed during stretching and bending, so-called whitening. Occurs. In the present invention, the above-mentioned specific modified copolymer is used to improve the compatibility, and the modification improves the compatibility with the polyamide resin. Then, when these resin mixtures are melt-kneaded in the presence of an organic peroxide, a vinyl aromatic compound-diene compound, due to the bond between the terminal radical generated by the molecular cleavage reaction in the copolymer and the radical in the polyamide molecule. Graft branches are formed and intermolecular bonds between polyamide molecules and the copolymer molecules occur. The formation of this intermolecular bond imparts improved compatibility and good melt fluidity. The melt fluidity is governed by the composition of the polyamide resin and the copolymer and the addition amount of the organic peroxide, and if the balance between the composition ratios and the addition amount is greatly lost, good melt fluidity cannot be obtained.

Further, in the resin composition of the present invention, the properties such as flexibility, chemical resistance, heat resistance and mechanical strength are adjusted within a preferable range by appropriately selecting the proportions of the polyamide resin, the modified copolymer and the organic peroxide. can do. Furthermore, an important advantage of the composition according to the invention is that the moldings obtained therefrom exhibit excellent whitening resistance.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples.

The polyamide resin compositions obtained in the respective examples and comparative examples were dried in a vacuum dryer at 70 ° C. for 16 hours, and then ASTM test pieces were molded at a polymer temperature of 250 ° C. and a mold temperature of 60 ° C. to obtain various physical properties. Made a characteristic. In addition, when evaluating the whitening resistance, a No. 3 dumbbell with a thickness of 2 mm was used.
It was folded in half every time, and the bent portion was visually observed.

Reference Example Clayton G-1657 (SHELL CHEMICAL CO., SEBS block copolymer, S / EB = 14/86% by weight) 100 parts maleic anhydride 0.5 parts and dicumyl peroxide 0.2 parts dissolved in a small amount of acetone were dried. Blended. This blend was set at a cylinder temperature of 200-240 ° C. 40
Melt kneading was carried out using a mmφ single-screw extruder and pelletization was carried out to obtain a modified styrene-olefin copolymer.

Example 1 Nylon 6 (relative viscosity 2.53, 98% sulfuric acid 1 g / 100 c.
c. 25 ° C.) 50 parts and 0.3 part of dicumyl peroxide was added to a mixture of 50 parts of the modified styrene / olefin copolymer obtained in the above Reference Example, and the mixture was uniformly mixed.
Melt-kneading extrusion was carried out at a cylinder temperature of 240 ° C. in a mφ twin-screw extruder to produce pellets. Test pieces were molded from this and various physical properties were measured.

Example 2 Nylon 6 (relative viscosity of 3.52, 98% sulfuric acid 1 g / 100)
cc 25 ° C) 60 parts and modified styrene obtained in the above reference example
The same operation as in Example 1 was performed using 40 parts of the olefin copolymer and 0.3 part of dicumyl peroxide.

Comparative Example 1 The same operation as in Example 1 was repeated using an unmodified styrene / olefin copolymer instead of the modified styrene / olefin copolymer used in Example 1.

Comparative Example 2 The same operation as in Example 1 was performed except that dicumyl peroxide was omitted in Example 1.

Comparative Example 3 The same operation as in Example 1 was performed except that the amount of dicumyl peroxide was changed to 3 parts.

Comparative Example 4 Only nylon 6 used in Example 1 was molded as it was.

The results are shown in Table 1.

As can be seen from Table 1, the polyamide resin composition of the present invention has superior mechanical property values to those of the comparative examples, and also has improved melt flowability and excellent moldability.

〔The invention's effect〕

The polyamide resin composition of the present invention having the above constitution is useful as an engineering plastics, but it can be further formed into a fiber, a film and a sheet, and has flexibility, chemical resistance, oil resistance and resistance. It is used in a wide range of applications such as extrusion molded products such as tubes, hoses and belts to injection molded products such as sound deadening gears, as engineering plastics with various properties such as impact resistance and whitening resistance.

Claims (1)

[Claims] 1. A copolymer containing a polyamide (A), a modified copolymer (B) and an organic peroxide (C), wherein the modified copolymer (B) comprises a vinyl aromatic compound and a conjugated diene compound. An unsaturated carboxylic acid or its derivative is graft-copolymerized on a part or all of the combined product and / or its hydride, and the amount of the organic peroxide (C) is equal to the total amount of (A) and (B). The polyamide composition is characterized by 0.01 to 2.5% by weight.