JPH07324151A - Styrene polymer composition - Google Patents

Abstract

PURPOSE:To obtain a styrene polymer composition improved in impact resistance and reduced in the anisotropy of mechanical strengths otherwise forming during extrusion. CONSTITUTION:This composition comprises 20-70wt.% nonrubber-modified styrene polymer, 30-70wt.% block copolymer comprising a conjugated diolefin and a vinyl-substituted aromatic compound and having a content of the vinyl- substituted aromatic compound of 65-90wt.%, 1-4wt.% block copolymer comprising a conjugated diolefin and a vinyl-substituted aromatic compound and having a content of the vinyl-substituted aromatic compound of 15-50wt.% and 1-20wt.% high-impact rubber-modified styrene polymer having a mean rubber particle diameter of 0.2-4.0mum and a content of the elastomer of 3-15wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrenic polymer composition, and more specifically, it has high transparency and impact resistance useful as a film or sheet material, and has anisotropy in mechanical strength generated during extrusion molding. The present invention relates to a styrene polymer composition having improved properties.

[0002]

2. Description of the Related Art Conventionally, a block copolymer comprising a vinyl-substituted aromatic compound and a conjugated diolefin is blended with polystyrene as a method for improving the drawbacks of polystyrene which is brittle and poor in impact strength without lowering transparency. The method has been used (Japanese Patent Publication No. 45-19388 and Japanese Patent Publication No. 47-43618). According to this method, when a block copolymer having a high vinyl substituted aromatic compound content is used, the transparency is excellent, but the impact strength is not so improved. On the other hand, when a block copolymer containing a small amount of vinyl-substituted aromatic compound is used, impact strength is improved to some extent, but compatibility with polystyrene is lowered and transparency is lost, so that more effective improvement is obtained. A method was desired.

After that, trials of methods for providing both transparency and impact resistance have been made, for example, in JP-B-56-50903 and JP-B-59-43059, in which a vinyl-substituted aromatic compound having a low vinyl-substituted aromatic compound content is used. A method of blending polystyrene with a block copolymer composed of a group compound and a conjugated diolefin compound and a block copolymer having a high vinyl-substituted aromatic compound content is described. Further, a method of further blending an impact-resistant rubber-modified styrene-based polymer with these compositions is disclosed in JP-B-60-10052, JP-B-62-31017, and JP-B-63-89.
No. 81 publication.

In the latter attempt, the blending ratio of each component and the impact-resistant rubber-modified styrene-based polymer have not been fully optimized, and a method of combining the contradictory properties of transparency and impact resistance has been proposed. It was still not enough.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a high transparency, a sufficient impact resistance for practical use, and anisotropy in mechanical strength generated during extrusion molding. Another object of the present invention is to provide a styrene polymer composition having improved properties.

[0006]

As a result of various studies, the inventor has found that a block copolymer comprising a vinyl-substituted aromatic compound having a low vinyl-substituted aromatic compound content and a conjugated diolefin compound and a vinyl-substituted aromatic compound. A block copolymer having a high group compound content is blended with a non-rubber-modified styrene-based polymer in a specific amount, and the rubber particle size of the impact-resistant rubber-modified styrene-based polymer, the content of the elastomer, and the composition are further added. By specifying the blending amount,
Balanced conflicting transparency and impact resistance at a high level,
The effect of improving the anisotropy of mechanical strength was also found, and the present invention was completed.

That is, the above-mentioned problems of the present invention include "(A) 20% by weight or more and 70% by weight or less of non-rubber-modified styrenic polymer, and (B) the content of vinyl-substituted aromatic compound is 65% by weight or more and 90% by weight. % Or less of a block copolymer composed of a conjugated diolefin and a vinyl-substituted aromatic compound, 30% by weight or more and 70% by weight or less, and a (C) vinyl-substituted aromatic compound content of 15% by weight or more and 50% by weight or less Impact resistance having a block copolymer consisting of a diolefin and a vinyl-substituted aromatic compound in an amount of 1% by weight or more and 4% by weight or less, and (D) an average rubber particle diameter of 0.2 to 4.0 μm and an elastomer of 3 to 15% by weight. Styrene-based polymer composition comprising 1% by weight or more and 20% by weight or less of a rubber-modified styrene-based polymer ".

The present invention will be described in detail below.

The non-rubber-modified styrenic polymer of the component (A) used in the present invention is obtained by polymerizing a vinyl-substituted aromatic compound or a monomer copolymerizable therewith. Examples of the monomer copolymerizable with the vinyl-substituted aromatic compound include α-methylstyrene, o-methylstyrene, p-methylstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, and maleic anhydride. Particularly preferred non-rubber-modified styrene-based polymers include polystyrene, acrylonitrile-styrene copolymer, acrylic ester-styrene copolymer, methacrylic acid ester-styrene copolymer, maleic anhydride-styrene copolymer and the like. These may be used alone or as a mixture of two or more depending on the purpose.

The block copolymers of the components (B) and (C) are produced by a conventionally known method, and generally, an anionic polymerization initiator is used in a hydrocarbon solvent to block the conjugated diolefin and the vinyl-substituted aromatic compound. Copolymerize. The structure of the block copolymer is a linear block copolymer (AB) n A (BA) n B (AB) n represented by the general formula (I) (wherein A is vinyl. A block containing a substituted aromatic compound as a main component, B is a block containing a conjugated diolefin as a main component, and n is an integer of 1 or more and is generally 1 to 6.) Alternatively, it is represented by the general formula (I). Radial block copolymer ◎ [(BA) n] m + 2-X [(AB) n] m + 2-X [(BA) n-B] m + 2-X [ (AB) n-A] m + 2-X (wherein A is a block containing a vinyl-substituted aromatic compound as a main component, B is a block containing a conjugated diolefin as a main component, X is silicon tetrachloride, etc.) , And n and m are integers of 1 or more and are generally 1 to 6).

In the present invention, a mixture of a linear block copolymer and a radial block copolymer, a mixture of two or more kinds of linear block copolymers and two or more kinds of radial blocks are used according to the purpose. Mixtures of copolymers can be used. In the block copolymer, the boundary between the A block and the B block does not necessarily have to be clear, and the structure of the block copolymer may include a complete block copolymer and a tapered block copolymer.
That is, the A block may contain a small amount of the B component, or the B block may contain a small amount of the A component. Furthermore, when the block copolymer has a plurality of A blocks, it is not necessary that all A blocks have the same molecular weight and composition, and the same applies to B blocks.

The vinyl-substituted aromatic compounds constituting the components (B) and (C) of the block copolymer used in the present invention include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene and vinyl. Naphthalene, vinyl anthracene and the like, especially styrene can be mentioned. These can be used alone or as a mixture of two or more types depending on the purpose. The conjugated diolefin is a diolefin having a conjugated double bond, and is, for example, 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, etc., and particularly 1,3-butadiene and isoprene are Can be mentioned. These can be used alone or as a mixture of two or more types depending on the purpose.

The weight average molecular weights of the components (B) and (C) of the block copolymer used in the present invention are
30,000 or more, preferably 50,000 or more 35
It is less than 2,000.

The impact-resistant rubber-modified styrene polymer as the component (D) used in the present invention is a vinyl-substituted aromatic compound or a copolymer of a monomer copolymerizable with the compound and an elastomer, and is generally a block. It can be obtained by polymerization, suspension polymerization, emulsion polymerization, bulk-suspension polymerization, or the like. Examples of the monomer copolymerizable with the vinyl-substituted aromatic compound include α-methylstyrene, o-methylstyrene, p
-Methylstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, maleic anhydride and the like. As the elastomer, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene random or block rubber, acrylic rubber, ethylene-
Examples thereof include propylene rubber, butyl rubber, nitrile rubber and the like. Particularly preferred impact-resistant rubber-modified styrene-based polymers are impact-resistant rubber-modified styrene polymers, acrylonitrile-butadiene-styrene copolymers, acrylate-butadiene-styrene copolymers, methacrylate-butadiene-styrene copolymers. Examples thereof include polymers, and these may be used alone or as a mixture of two or more types depending on the purpose. Further, the impact-resistant rubber-modified styrene-based polymer is an impact-resistant rubber-modified styrene-based polymer having an average rubber particle size of 0.2 to 4.0 μm and an elastomer of 3 to 15% by weight.

The styrenic polymer composition of the present invention contains, in addition to the four-component polymer, an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a reinforcing material, a slip agent, an antiblocking agent, if necessary. Nucleating agent, crosslinking agent, antistatic agent, antifogging agent,
Additives such as flame retardants, pigments and dyes may be included.

As a method for obtaining the styrene polymer composition of the present invention, any conventionally known means can be used. For example, a method of mixing the raw materials in a tumbler type blender, a ribbon blender, a V type blender, a Henschel mixer, or the like, and a method of melting and kneading the mixture mixed by the above method with an extruder, a kneader, a Banbury mixer, or the like are used. The obtained styrene-based polymer composition of the present invention can be processed into various products by using any conventionally known molding method. As the processing method,
Examples include injection molding, extrusion molding, extrusion foam molding, biaxial stretching, blow molding, pressure molding of a film, sheet and foam, vacuum molding and the like.

[0017]

The styrene-based polymer composition of the present invention can improve the impact resistance and the anisotropy of mechanical strength without impairing the transparency by using the respective four components in the specified amounts as described above. The blend ratio is shown below. Component (A); 20 wt% or more and 70 wt% or less Component (B); 30 wt% or more and 70 wt% or less Component (C); 1 wt% or more and 4 wt% or less Component (D); 1 wt% or more and 20 wt% % Or less If the content of the component (A) is less than 20% by weight, the rigidity of the composition becomes low and the molded product loses commercial value. If it is more than 70% by weight, the composition is less than Although it has high rigidity, it lowers impact resistance and increases the anisotropy of mechanical strength. When the amount of the component (B) is less than 30% by weight, the transparency of the composition becomes low, the impact resistance is lowered, and the anisotropy of mechanical strength is increased. 70% by weight
If more than that, the rigidity of the composition will be low. When the content of the component (C) is less than 1% by weight, the impact resistance of the composition is lowered and the anisotropy of mechanical strength is increased, and when it is more than 4% by weight, the transparency is increased. Will be lower.
When the content of the component (D) is less than 1% by weight, the impact resistance of the composition is lowered, and the anisotropy of mechanical strength becomes strong. The anisotropy of the mechanical properties and mechanical strength is improved, but the transparency is reduced.

Further, if each component is limited to the following range,
The balance between transparency, impact resistance, mechanical strength anisotropy and rigidity is the best.

Component (A); 40 wt% or more and 70 wt% or less Component (B); 30 wt% or more and 70 wt% or less Component (C); 1 wt% or more and 4 wt% or less Component (D); 1 wt% 20% by weight or less and component (B) of the block copolymer used in the present invention,
(C) contains (B) a vinyl-substituted aromatic compound in an amount of 65% by weight or more and 90% by weight or less, and a conjugated diolefin component in an amount of 10% by weight or more and 35% by weight or less,
(C) The content of the vinyl-substituted aromatic compound is 15% by weight or more and 50% by weight or less, and the conjugated diolefin component is 50% by weight.
The above content is 85% by weight or less.

When the content of the vinyl-substituted aromatic compound in the block copolymer (B) is more than 90% by weight, not only the impact resistance of the block copolymer itself becomes low, but also the ratio of the present invention. Even when the respective components are blended with each other, the impact resistance and the anisotropy of mechanical strength of the composition can hardly be improved. Further, when the content of the vinyl-substituted aromatic compound in the block copolymer (B) is less than 65% by weight, impact resistance and anisotropy of mechanical strength of the composition are improved, On the other hand, the compatibility with the non-rubber-modified styrenic polymer is reduced, resulting in poor transparency. When the content of the vinyl-substituted aromatic compound in the block copolymer (C) is more than 50% by weight,
The impact resistance and mechanical strength anisotropy of the composition can hardly be improved. Further, when the content of the vinyl-substituted aromatic compound in the block copolymer (C) is less than 15% by weight, impact resistance and anisotropy of mechanical strength of the composition can be improved. As a result, the compatibility with the non-rubber-modified styrenic polymer is lowered and the transparency is deteriorated.

When the average rubber particle size of the impact-resistant rubber-modified styrene polymer as the component (D) is smaller than 0.2 μm, the impact resistance and mechanical strength anisotropy of the composition are not improved. . Further, when it is larger than 4.0 μm, the transparency is remarkably lowered. If the elastomer content is less than 3% by weight, impact resistance and mechanical strength anisotropy are not improved. When it is more than 15% by weight, the transparency is significantly lowered.

[0022]

EXAMPLES The present invention will be described in more detail below with reference to examples. The embodiments of the present invention are not limited to the following examples. The resins used in this experiment are listed below. Component A; Sample 1 ... General-purpose polystyrene Component B; Sample 2 ... Styrene-butadiene block copolymer with styrene content of 80 wt% Sample 3 ... Styrene-butadiene block copolymer with styrene content of 70 wt% Component C; Sample 4 ... Styrene content 40 wt% styrene-butadiene block copolymer Component D; high impact polystyrene

[Table 1] The evaluation method and criteria in the experiment are described below. Drop weight impact test ... Complies with ASTM D1709. Hammer tip R 1/2 inch. The larger the value, the higher the impact resistance. MIT folding endurance test ... According to JIS P8115. Load 1kg
f, bending angle 135 °. The anisotropy is improved when the difference in strength between MD and TD is small. Haze ... Compliant with ASTM D1003. The smaller the value, the better the transparency. Waist ... Tensile elastic modulus was calculated by a tensile test based on JIS K7127, and the waist was judged from the value. When the sheet thickness is 0.25 mm and the tensile elastic modulus is 20000 kg / cm 2 or more, it is assumed to be stiff and is indicated by a circle. Tensile modulus 200
When it was less than 00 kg / cm2, it was assumed to be stiff and indicated by a cross.

(Examples 1 to 5) The respective components were mixed in a tumbler type blender according to the blending ratio shown in Table 1 to obtain 65
A sheet having a thickness of 0.25 mm was formed with a sheet extruder having a diameter of mm. The evaluation results of the obtained sheet are shown in Table 2. To meet practical requirements, the haze must be 14% or less. Further, the falling weight impact strength is required to be 1.5 kgcm or more, and the folding endurance is required to exceed 100 times in both MD / TD and the difference in MD / TD strength is small. Compared with the evaluation results of Reference Examples and Comparative Examples, the haze, which is a measure of transparency, is as low as 5% or less, the falling weight impact strength is 1.5 kgcm or more, and the folding endurance is 100 times both MD / TD. It is clear that the degree of improvement in transparency, impact strength, and anisotropy of mechanical strength are balanced at a high level because the difference between the two is not so large.

(Comparative Example 1) A test example within the disclosure content range of the prior art document and a component A content of more than 70% by weight, or a component B content of less than 30% by weight, Alternatively, when the content of the component C was more than 4% by weight, the transparency decreased.

(Comparative Example 2) The content of component A is 20% by weight.
When the amount is less than the above amount, or when the amount of the component B is more than 70% by weight, the transparency and impact resistance are excellent, but the sheet is not stiff and the value as a molded article decreases.

(Comparative Example 3) The content of component A is 70% by weight.
More than the above, or the amount of ingredient B is 30% by weight
If less than that, the impact resistance is poor.

(Comparative Example 4) The styrene content of component B is 6
When it is less than 5% by weight, the transparency is poor.

(Comparative Example 5) When the content of the component C is less than 1% by weight, or the styrene content of the component C is 5%.
When it is more than 0% by weight, the impact resistance is poor and the anisotropy of mechanical strength is not improved.

(Comparative Example 6) When the content of component C is more than 4% by weight, the transparency is poor.

(Comparative Example 7) When the content of the component D is less than 1% by weight, the impact resistance is poor and the anisotropy of mechanical strength is not improved.

(Comparative Example 8) The compounding amount of component D is 20% by weight.
If the amount is larger than that, the transparency is poor.

(Comparative Examples 9 and 10) When the average rubber particle diameter of impact-resistant polystyrene is smaller than 0.2 μm, the transparency is not so different from that in Example 1, the impact strength is poor, and the mechanical strength is different. The orientation is not improved either. When the average rubber particle size of the high impact polystyrene is larger than 4.0 μm,
The transparency was lower than that of Example 1.

(Comparative Examples 11 and 12) When the elastomer content of the impact-resistant polystyrene is less than 3% by weight, the transparency is not so different from that of Example 1 and the impact strength is poor and the mechanical strength is anisotropic. The sex is not improved either. When the elastomer component of the high impact polystyrene was more than 15% by weight, the transparency was decreased as compared with Example 1.

[0034]

[Table 2]

[0035]

The film and sheet of the styrenic polymer composition of the present invention obtained by the above method have high transparency and impact resistance, and the anisotropy of mechanical strength generated during extrusion molding is also improved. In addition, it can be vacuum-formed like polyvinyl chloride and has good moldability. It has better rigidity than polypropylene and polyethylene films, and is cheaper than amorphous polyester film (A-PET). Since it has excellent container formability such as vacuum forming, it can be used for packaging of foods and the like.

Claims (2)

[Claims] 1. A conjugated diolefin and vinyl containing (A) a non-rubber-modified styrene polymer in an amount of 20% by weight or more and 70% by weight or less and (B) a vinyl-substituted aromatic compound content of 65% by weight or more and 90% by weight or less. Block copolymer consisting of a substituted aromatic compound 30% by weight or more and 70% by weight or less, (C) vinyl substituted aromatic compound content of 15% by weight or more and 50% by weight
The block copolymer consisting of the following conjugated diolefin and vinyl-substituted aromatic compound is 1% by weight or more and 4% by weight or less, and (D) the average rubber particle diameter is 0.2 to 4.0 μm, and the elastomer is 3 to 15% by weight. A styrene polymer composition comprising 1% by weight or more and 20% by weight or less of the impact-resistant rubber-modified styrene polymer. 2. The content of component (A) is 40% by weight or more and 70
The styrene-based resin composition according to claim 1, wherein the styrene-based resin composition is contained in an amount of not more than wt%.