JPH07324150A - High-impact styrene resin composition - Google Patents

Abstract

PURPOSE:To obtain a high-impact styrene resin composition improved in impact resistance and reduced in the anisotropy of mechanical strengths otherwise forming during extrusion. CONSTITUTION:This composition comprises 65-85wt.% nonrubbermodified styrene polymer, 3-18wt.% 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.%, 2-8wt.% 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 to below 10wt.% 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]

FIELD OF THE INVENTION The present invention relates to a styrene resin composition. More specifically, the present invention relates to a styrene resin composition which is useful as a film or sheet material, which is excellent in transparency and impact resistance and has improved anisotropy of mechanical strength generated during extrusion molding.

[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 An object of the present invention is to have a high transparency, which has not been sufficiently obtained by the conventional method, has a sufficient impact resistance for practical use, and has a mechanical strength generated during extrusion molding. An object of the present invention is to provide an impact resistant styrene resin composition having improved anisotropy.

[0006]

Means for Solving the Problems As a result of intensive studies by the inventor, 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 large compound content is blended with a non-rubber-modified styrene-based polymer in a specific amount, and further added, the rubber particle size of the impact-resistant rubber-modified styrene-based polymer, the content of the elastomer, and the composition By specifying the 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, an object of the present invention is to provide "(A) a non-rubber-modified styrene-based polymer of 65% by weight or more and 85% by weight or less,
(B) Block copolymer comprising a vinyl-substituted aromatic compound and a conjugated diolefin having a vinyl-substituted aromatic compound content of 65% by weight or more and 90% by weight or less and 3% by weight or more 18
2% by weight or more and 8% by weight or less of a block copolymer composed of a conjugated diolefin having a vinyl substituted aromatic compound content of 15% by weight or more and 50% by weight or less and a vinyl substituted aromatic compound, and (D) Impact-resistant rubber-modified styrene polymer having an average rubber particle diameter of 0.2 to 4.0 μm and an elastomer of 3 to 15% by weight 1% by weight or more 1
Styrene resin composition of less than 0% by weight ”.

The present invention will be described in detail below.

The non-rubber modified styrene polymer (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, maleic anhydride and the like can be mentioned. Particularly preferred non-rubber-modified styrene-based polymers include polystyrene, acrylonitrile-styrene copolymer, acrylic acid 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 obtained as a linear block copolymer represented by the general formula or a radial block copolymer represented by the general formula.

(A-B) n A (BA) n B (A-B) n (I) (wherein A is a block containing a vinyl-substituted aromatic compound as a main component, and B is a conjugated diolefin). , Where n is an integer of 1 or more and is generally 1 to 6.) [(B-A) n] m + 2-X [(A-B) n] m + 2-X [(BA) n-B] m + 2-X [(AB) n-A] m + 2-X ... (ΙΙ) (A in the formula is a vinyl-substituted aromatic compound as a main component. Block, B is a block containing a conjugated diolefin as a main component, X is a coupling agent such as silicon tetrachloride, n and m are integers of 1 or more and are generally 1 to 6.) In the present invention, the purpose is A mixture of a linear block copolymer and a radial block copolymer, a mixture of two or more linear block copolymers and two or more Mixtures of al block 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. further,
When the block copolymer has a plurality of A blocks,
The molecular weight and composition of all A blocks need not be the same,
The same applies to the B block.

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. Further, 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 and the like, particularly 1,3-butadiene and isoprene. 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 styrenic polymer (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 bulk polymerization, It can be obtained by 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, and maleic anhydride. Examples of the elastomer include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene random or block rubber, acrylic rubber, ethylene-propylene rubber, butyl rubber and nitrile rubber. 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 impact-resistant styrenic resin composition of the present invention contains a UV absorber, an antioxidant, a lubricant, a plasticizer, a reinforcing material, a slip agent, an anti-blocking agent, if necessary, in addition to the four-component polymer. Additives such as agents, nucleating agents, crosslinking agents, antistatic agents, antifogging agents, flame retardants, pigments and dyes may be included.

As a method for obtaining the impact resistant styrene resin 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 impact resistant styrene resin 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.

[0018]

The impact-resistant styrenic resin composition of the present invention improves the impact resistance and the mechanical strength anisotropy without deteriorating the transparency by using each of the four components in a specified amount as described above. The blend ratio is as shown below.

Component (A); 65 wt% or more and 85 wt% or less Component (B); 3 wt% or more and 18 wt% or less Component (C); 2 wt% or more and 8 wt% or less Component (D); 1 wt% Above 10% by weight If the content of component (A) is less than 65% by weight, the rigidity of the composition becomes low and the molded article loses commercial value. If it is more than 85% by weight, Although the composition has high rigidity, it lowers impact resistance and increases the anisotropy of mechanical strength. When the content of the component (B) is less than 3% by weight, the transparency of the composition is low, and when it is more than 18% by weight, the rigidity of the composition is low. When the amount of the component (C) is less than 2% by weight, the impact resistance of the composition is lowered and the anisotropy of mechanical strength is increased, and when it is more than 8% by weight, the transparency is high. Will be lower. Ingredient (D)
When the content is less than 1% by weight, the impact resistance of the composition is lowered and the mechanical strength anisotropy becomes strong,
If it is 0% by weight or more, impact resistance and anisotropy of mechanical strength are improved, but transparency is lowered.

Further, if each component is limited to the following range, the balance of transparency, impact resistance, mechanical strength and rigidity of the sheet will be optimum. Component (A); 65 wt% or more and 80 wt% or less Component (B); 3 wt% or more and 18 wt% or less Component (C); 2 wt% or more and 8 wt% or less Component (D); 1 wt% or more and 10 wt% Less than% Component (B) of the block copolymer used in the present invention,
(C) is shown in Table 1.

[0021]

[Table 1] 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 is lowered, but also each component is added in the ratio of the present invention. Even when blended, 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 the anisotropy of mechanical strength of the composition are almost improved. I can't. Further, the block copolymer (C)
When the content of the vinyl-substituted aromatic compound in the composition is less than 15% by weight, the impact resistance and the anisotropy of mechanical strength of the composition can be improved, but the phase relative to the non-rubber-modified styrene polymer is improved. As a result, the compatibility is lowered and the transparency is deteriorated.

Impact-resistant rubber-modified styrene polymer (D)
When the average rubber particle size of is less than 0.2 μm, the impact resistance and the anisotropy of mechanical strength 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.

[0024]

The present invention will be described in more detail with reference to the following examples, but the embodiments of the present invention are not limited thereto. 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 70 wt% Component (C); Sample 3 ... Styrene-butadiene block copolymer with styrene content of 40 wt% Combined component (D); high impact polystyrene (shown in Table 2)

[Table 2] The evaluation method and standard in this 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 tensile modulus of elasticity is 20000 kg / cm 2 or more at a sheet thickness of 0.25 mm, the sheet is stiff and marked with a circle. When the tensile modulus of elasticity is less than 20000 kg / cm 2, it is indicated by x as having no stiffness.

(Examples 1 to 4) According to the blending ratio shown in Table 1, the respective components were mixed in a tumbler type blender 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 3. 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 the comparative example, the haze, which is a measure of transparency, is 1
It is as low as 0% or less, the impact strength of falling weight is 2 kgcm or more, and the folding strength and MD / TD exceeds 100 times, and the difference between the two is not so large. Therefore, the transparency, impact strength and mechanical strength are different. It is clear that the degree of improvement in directionality is well balanced.

(Comparative Example 1) When the content of the test example and the component C in the disclosure content range of the prior art document was more than 8% by weight, the impact resistance was excellent, but the transparency was lowered.

Comparative Example 2 It can be seen that the composition containing only components A and B is inferior in impact resistance.

(Comparative Example 3) The content of the component A is 85% by weight.
If it is more than the above, or if the content of the component B is less than 3% by weight, or if the styrene content of the component B is less than 65% by weight, the impact resistance is poor and the transparency is also lowered.

(Comparative Example 4) The content of the component A is 65% by weight.
When the amount is less than the above, or when the content of the component B is more than 18% by weight, the sheet becomes less stiff and the value as a molded article is reduced.

(Comparative Example 5) When the content of the component C is less than 2% 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.

(Comparative Example 6) When the content of the component D is less than 1% by weight, the impact resistance is poor.

(Comparative Example 7) The content of component D is 10% by weight.
If it is more than that, the rigidity of the sheet is lost and the transparency is reduced.

(Comparative Examples 8 and 9) When the average rubber particle diameter of impact-resistant polystyrene is smaller than 0.2 μm, the transparency is not so different from that of Example 1 and the impact resistance is poor and the mechanical strength is low. Anisotropy is not improved either. When the average rubber particle size of the impact-resistant polystyrene was larger than 4.0 μm, the transparency was lower than that in Example 1.

(Comparative Examples 10 and 11) When the elastomer component 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 resistance is poor and the mechanical strength is different. The orientation 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.

[0035]

[Table 3]

[0036]

The film and sheet of the impact resistant styrene resin composition obtained in the present invention have high transparency and impact resistance, and have improved anisotropy of mechanical strength generated during extrusion molding. Also, like PVC, it can be vacuum-formed and has good moldability. It has better rigidity than polypropylene and polyethylene films, and is cheaper and vacuumer than amorphous polyester film (A-PET). Since it is excellent in container moldability such as molding, it can also be used for packaging foods and the like.

Claims (2)

[Claims] 1. A conjugated diolefin and vinyl containing (A) a non-rubber-modified styrenic polymer of 65% by weight or more and 85% 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 3 wt% or more and 18 wt% or less, (C) vinyl substituted aromatic compound content of 15 wt% or more and 50 wt% or less conjugated diolefin and vinyl substituted aromatic compound 2% to 8% by weight of a block copolymer consisting of and (D) an impact-resistant rubber-modified styrene polymer 1 having an average rubber particle diameter of 0.2 to 4.0 μm and an elastomer of 3 to 15% by weight. A styrene-based resin composition comprising at least 10% by weight. 2. The content of component (A) is 65% by weight or more and 80.
The styrene-based resin composition according to claim 1, wherein the styrene-based resin composition is contained in an amount of not more than 5% by weight.