JP3192253B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent resin composition having improved surface impact, particularly a container, a housing, a case, a cover obtained by injection molding, and a sheet obtained by extrusion molding. The present invention relates to a resin composition suitable for a transparent molded product requiring a high degree of transparency and surface impact such as a container or a case obtained by performing a vacuum molding, a bending molding, a press molding, or the like.

[0002]

2. Description of the Related Art A block copolymer resin comprising a vinyl aromatic hydrocarbon and a conjugated diene is a resin having excellent transparency and impact properties, and is widely used in sheets, films, injection molded articles and the like. However, there is a trade-off relationship in that the resin with excellent impact resistance has low rigidity, while the resin with high rigidity has low impact resistance. The reality is that the coalescing resin has not yet been obtained.

[0003] An attempt to improve the Izod impact strength as an impact property is disclosed in Japanese Patent Publication No. 52-16496. When rubber-modified polystyrene is added in an amount of 15% or more, impact strength is improved, but transparency is significantly reduced. Also 0.
At a blending amount of 5%, the impact strength, strength and rigidity are equivalent to those at a blending amount of 0%, and no improvement effect is recognized. Tokunosho 5
Japanese Unexamined Patent Publication No. 9-25821 discloses a rubber-modified impact-modified styrene polymer modified with a block copolymer having a specific structure and a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene. And a polymer composition having good transparency. However, the disclosed rubber-modified impact-resistant styrene polymer has a lower Izod impact strength than that of the conventional rubber-modified impact-resistant styrene polymer, and does not have sufficient impact strength.

JP-A-51-89550 discloses a transparent impact-resistant styrenic polymer composition comprising a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene, a rubber-modified styrene polymer and a styrene polymer. Is disclosed. However, even in this composition, there is no composition which is satisfactory in both transparency and impact properties.

[0005]

Injection molded products such as covers, cases and housings or extruded sheets requiring high transparency, rigidity and surface impact as described above, as well as vacuum molding, press molding and bending molding. The present invention provides a composition which has improved trade-off rigidity and impact resistance at the same time while maintaining a high degree of transparency in a container or case.

[0006]

According to the present invention, there is provided a thermoplastic block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene, wherein a very small amount of a rubber-modified impact-resistant polystyrene having a specific particle size is blended. Maintains the original transparency of the block copolymer, and in a molded product with high rigidity,
We have found that surface impact can be dramatically improved.

That is, the present invention relates to (a) a thermoplastic block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene, wherein the content of the vinyl aromatic hydrocarbon is from 65% by weight to 85% by weight. 95% by weight or more of copolymer 9
9.7% by weight or less and (b) rubber-modified impact-resistant polystyrene in which rubber particles obtained by graft-polymerizing styrene with a butadiene-based rubber-like polymer have an average particle diameter of 1.5 μm or more. A resin composition comprising 0.3% by weight or more and 5% by weight or less, or the composition of the above (a) or (b) and (C) polystyrene, vinyl aromatic hydrocarbon- (meth) acrylate copolymer. A resin composition comprising one or more selected resins, wherein (a) + (b) +
(B) is a resin composition of 0.3% by weight or more and 5% by weight or less with respect to (c) = 100% by weight, and (c) is a resin composition of 5% by weight or more and 70% by weight or less.

The block copolymer of the component (a) used in the present invention is a polymer obtained by anionic polymerization of a vinyl aromatic hydrocarbon and a conjugated diene in a hydrocarbon solvent, and substantially comprises at least two vinyl aromatic hydrocarbons. A mainly composed of aromatic hydrocarbons
A polymer having a segment and a B segment mainly composed of at least one conjugated diene, which can be represented by the following general formula, wherein an A segment mainly composed of one vinyl aromatic hydrocarbon and one or two A polymer composed of B segments mainly composed of two conjugated dienes may be contained as long as the content is 30% by weight or less.

A- (B−A) _n , B−A− (B−A) _n , (
_{A- B) - J X- (B-} A- B) k ( an integer of where n, j, k is from 1 to 5, j,
k represents an integer satisfying 2 ≦ j + k ≦ 6, and X represents a residue of a coupling agent or a residue of a polyanion initiator. The polymer which may be contained in an amount of 30% by weight or less is AB
Alternatively, it can be represented by BAB. A) A segment mainly composed of vinyl aromatic hydrocarbon means a vinyl aromatic hydrocarbon homopolymer and / or a copolymer segment of vinyl aromatic hydrocarbon and conjugated diene containing 50% by weight or more of vinyl aromatic hydrocarbon. The B segment mainly composed of a conjugated diene is a homopolymer of a conjugated diene and / or a copolymer segment of a vinyl aromatic hydrocarbon having a conjugated diene content of 50% by weight or more and a conjugated diene. The boundaries between these segments A and B need not always be clear, and the distribution of each monomer in the copolymerized portion may be uniformly random or tapered.

The vinyl aromatic hydrocarbon constituting the block copolymer includes, for example, styrene, o-methylstyrene,
p-methylstyrene, p-tert-butylstyrene,
α-methylstyrene, vinylnaphthalene, vinylanthrene, 1,1-diphenylethylene and the like. These may be used alone or in combination of two or more. When importance is placed on heat resistance, it is preferable to use 1,1-diphenylethylene as a copolymer monomer.

Therefore, the content of the vinyl aromatic hydrocarbon in the block copolymer is from 65% by weight to 85% by weight, preferably from 70% by weight to 80% by weight.
When the content of the vinyl aromatic hydrocarbon is less than 65% by weight or more than 85% by weight, the transparency of the composition is unpreferably reduced. A block copolymer having a high content of a polymer present as a vinyl aromatic hydrocarbon homopolymer in the block copolymer has excellent rigidity but low impact resistance. Conversely, the content of the homopolymer is low. A small amount of block copolymer is excellent in impact resistance but low in rigidity. Therefore, it is necessary to select the composition ratio of the vinyl aromatic hydrocarbon and the conjugated diene in accordance with the performance of the final composition and to select the content of the polymer present as the vinyl aromatic hydrocarbon homopolymer. is there. The preferred content of the polymer present as a vinyl aromatic hydrocarbon homopolymer is 60
% By weight or more and 80% by weight or less. The content of the polymer present as the vinyl aromatic hydrocarbon homopolymer can be measured by decomposing the block copolymer with osmic acid and reprecipitating it in methanol.

Examples of the conjugated diene constituting the block copolymer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-hexadiene, and these may be used alone or in combination. It may be used. The content of these conjugated diene monomers in the block copolymer is 15% by weight or more and 35% by weight or less, and is preferably 20% by weight or more and 30% by weight or less from the transparency of the composition.
% By weight or less.

These block copolymers can be prepared by known polymerization techniques, for example, an organic lithium compound or an organic sodium compound such as n-butyllithium or sec-butyllithium in a hydrocarbon solvent such as n-hexane, cyclohexane or toluene. Polymerization can be performed by a method of successively adding monomers using butadienyl dilithium or the like as an initiator, and after coupling with a polyfunctional coupling agent such as tin tetrachloride or a polyepoxy compound, if necessary, alcohol or It can be obtained by terminating the polymerization by adding water and removing the solvent. In addition, in order to control the polymerization rate and molecular weight distribution, microstructure such as vinyl structure of the conjugated diene part in the polymer, an appropriate amount of a polar compound represented by an ether compound such as tetrahydrofuran or tetramethylethylenediamine or an amine compound is added. It can also be polymerized.

Although the molecular weight of the block copolymer varies depending on the use, the MI (G condition) is 1 to 20 g / min.
If it is less than 1, the processability is poor, and if it exceeds 20, the strength of the product is undesirably reduced. The rubber-modified impact-resistant polystyrene of the component (b) used in the present invention is obtained by dissolving a butadiene-based rubber-like polymer in styrene, and then starting polymerization of styrene, under the condition that styrene is graft-polymerized to the rubber-like polymer. And a rubber-modified impact-resistant polystyrene in which the average particle diameter of the rubber particles formed by the grafted rubber-like polymer is 1.5 μm or more.

The average particle diameter as used herein means a transmission electron micrograph of a rubber-modified impact-resistant polystyrene by an ultra-thin section method, and measures the particle diameter of about 500 rubber particles in the photograph. It is calculated by the formula. Average particle diameter = ΣniDi ⁴ / ΣniDi ³ (where ni is the number of particles having a rubber particle having a major axis of Di). These rubber particles have a so-called salami structure in which a polystyrene portion is incorporated. It refers to a core-shell structure.

A rubber-modified impact-resistant polystyrene having an average particle size of less than 1.5 μm is not preferable because the effect of improving the surface impact is small. A more preferred average particle size is 1.8 μ or more. To control the average particle size of the rubber particles, the composition of the rubbery polymer dissolved in styrene, the degree of polymerization, the stirring state when polymerizing styrene, the polymerization initiator, the chain transfer agent, the graft ratio of rubber particles and the crosslinking It is possible by appropriately changing the degree.

The rubbery polymer used to obtain the rubber-modified impact-resistant polystyrene includes polybutadiene, styrene-butadiene random polymer, styrene-butadiene block copolymer and the like. Polybutadiene is preferable for improving the impact resistance, and styrene-butadiene copolymer obtained by copolymerizing styrene is preferable from the viewpoint of transparency. The blending amount of the rubber-modified impact-resistant polystyrene as the component (b) blended in the transparent resin composition of the present invention is used within a range that does not impair the original transparency of the block copolymer. Is a 2 mmt molded plate and a haze value of 3% or less is a standard, and a haze value of a sheet is preferably 3% or less in the thickness of a final product. The specific amount of the rubber-modified impact polystyrene is 0.3% in the composition with the block copolymer.
It is used in an amount of from 5% by weight to 5% by weight, preferably from 0.5% by weight to 3% by weight.

When the amount of the rubber-modified impact-resistant polystyrene is less than 0.3% by weight, the transparency is good, but the effect of improving the impact is small. Conversely, when the amount exceeds 5% by weight, the impact is improved. However, the transparency is extremely poor. In order to further improve the rigidity, surface hardness and heat resistance (thermal deformation temperature) or to improve the formability of the present invention, (c)
One or more resins selected from polystyrene and vinyl aromatic hydrocarbon- (meth) acrylate copolymers can be blended as components.

The amount of component (c) is (a), (b),
It is 5% by weight or more and 70% by weight or less, preferably 10% by weight or more and 60% by weight or less, more preferably 10% by weight or more and 50% by weight or less based on 100% by weight of the total of each component (c). When the amount of the component (c) is less than 5% by weight, rigidity is obtained.
The effect of improving heat resistance is poor, and if it exceeds 70% by weight, the rigidity increases but the impact resistance decreases. When the block copolymer of the component (a) is a block copolymer having a large content of a polymer present as a vinyl aromatic hydrocarbon homopolymer in the block copolymer, the amount of the component (c) is adjusted. On the contrary, when the amount of the block copolymer is small, the blending amount of the component (c) can be increased to balance the impact strength and the rigidity.

The monomers constituting the vinyl aromatic hydrocarbon- (meth) acrylate copolymer of the component (c) include the following. Vinyl aromatic hydrocarbons include styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, etc., and (meth) acrylic acid esters are methyl methacrylic acid esters;
Ethyl ester, n-butyl ester, i-butyl ester, t-butyl ester, 2-ethylhexyl ester, methyl ester of acrylic acid, ethyl ester, n
-Butyl ester, 2-ethylhexyl ester, etc.
It is an ester of (meth) acrylic acid and an alcohol having 1 to 8 carbon atoms.

The rigidity of the polymer of component (c) is as follows:
To improve heat resistance, styrene-methyl methacrylate copolymer is preferable, but if it is blended in a large amount, transparency becomes slightly inferior, and in order to maintain high transparency and at the same time improve processability, Styrene-butyl acrylate copolymer is preferred. In the styrene-methyl methacrylate copolymer and the styrene-butyl acrylate copolymer, the copolymer composition ratio of methyl methacrylate or butyl acrylate is from 10 to 30% by weight, preferably from 12 to 25%, from the transparency of the final composition. % By weight, but may contain 0.1 to 2% of other monomers.

The rubber-modified impact-resistant polystyrene of the component (b), the polystyrene of the component (c), and the MI (G) of the vinyl aromatic hydrocarbon- (meth) acrylate copolymer are obtained from the viewpoint of processability and product strength. 1 to 1 like the block copolymer
20 g / min is preferred. Various additives can be added to the transparent resin composition of the present invention as needed within a range that does not impair transparency, rigidity and impact resistance. These additives include a block copolymer elastomer of a vinyl aromatic hydrocarbon having a vinyl aromatic hydrocarbon content of 50% by weight or less and a conjugated diene, an antioxidant, an antistatic agent, an antifogging agent,
There are ultraviolet absorbers, lubricants, coloring agents, mineral oils, plasticizers and the like.

[0023]

EXAMPLES Examples of the present invention will be described below, but they do not limit the scope of the present invention. (A) Production of Block Copolymer of Component The block copolymers of A-1 to A-5 in Table 1 use n-butyllithium as an initiator in a cyclohexane solvent, and use styrene, a styrene / butadiene mixture, and styrene. Polymerization was performed by adding a cyclohexane solution of the monomer in order, and after stopping the polymerization with methanol, 2- (2-hydroxy-3-
t-butyl-5-methylbenzyl) -4-methyl-6
0.5 parts each of t-butylphenyl acrylate and trisnonylphenyl phosphite was added as a stabilizer to 100 parts of the block copolymer, and the solvent was distilled off. The amount of block styrene was measured by decomposing the block copolymer with osmic acid and reprecipitating in methanol. The addition amount of the styrene monomer was adjusted so that the GPC peak of the block styrene became one peak.
Melt flow (MI) was measured under G conditions.

[0024]

[Table 1]

Production of rubber-modified impact-resistant polystyrene of component (b) The rubber-modified impact-resistant polystyrene shown in Table 2 is obtained by dissolving the rubber shown in Table 2 in a styrene monomer and polymerizing in a reaction vessel equipped with a stirring blade. Unreacted monomers and the like were removed under reduced pressure. The average particle diameter of the rubber particles was adjusted by changing the rotation speed of the stirring blade.

[0026]

[Table 2]

Note 1) Polybutadiene rubber and styrene
The butadiene rubber is used in combination, and the weight ratio is 1/1. Production of the component (c) Table 3 shows the component (c) used. C-1 and C-2 are commercially available products, and C-3 and C-3 -4 was obtained by radical polymerization in the same manner as for the component (b).

[0028]

[Table 3]

Note 2) Asahi Kasei Polystyrene 666 manufactured by Asahi Kasei Kogyo Co., Ltd. 3) Estyrene MS manufactured by Nippon Steel Chemical Co., Ltd.
The MS-200 evaluation method is as follows. [Transparency] The haze was measured according to JIS K6714. [Impact Property] A DuPont impact value was measured by using a tester manufactured by Toyo Seiki Seisaku-sho, Ltd., and the radius of impact was 1/8 inch.

The impact strength at 0 ° C. was measured using a falling weight graphic impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd., using a 1-inch diameter hammer, and the energy [J] until the sheet was broken and the maximum stress at that time. [N] was determined. [Flexural modulus] Measured in accordance with ASTM D790. [Tensile Modulus] According to JIS K7113, the length and width of the sheet in the extrusion direction were measured, and the average was determined.

[0031]

Examples 1 to 3 and Comparative Examples 1 to 3 Test pieces having a thickness of 2 mmt were formed by press-molding a composition obtained by kneading rolls using the components (a), (b) and (c) shown in Table 4. To create
The haze was measured. The results are shown in Table 4.

[0032]

[Table 4]

[0033]

Examples 4 to 6 and Comparative Examples 4 to 6 The components (a) and (b) shown in Table 5 were pelletized by a co-rotating twin-screw extruder having a diameter of 30 mm and then tested by an injection molding machine to a thickness of 2 mm. Pieces were made and measured for Dupont impact value and haze at room temperature. Table 5 shows the results. When the component (b) having an average particle diameter of less than 1.5 μm is used, the effect of improving impact properties is poor, and the transparency is also deteriorated.

[0034]

[Table 5]

[0035]

Examples 7 to 11 and Comparative Examples 7 and 8 Dupont impact values and haze values of the compositions shown in Table 5 at room temperature were measured in the same manner as in Example 4. Table 5 shows the results. If the amount of the component (b) is less than 0.3%, the effect of improving the impact properties is poor,
If it exceeds 5.0%, the transparency is significantly reduced.

[0036]

Examples 12 to 25 and Comparative Examples 9 to 13 Dupont impact value, haze value and flexural modulus at room temperature of the compositions shown in Table 6 were measured in the same manner as in Example 4. Table 6 shows the results. If the amount of component (c) is less than 5% by weight, the effect of improving rigidity is poor. If it exceeds 70% by weight, the rigidity is increased but the impact properties cannot be improved.

[0037]

[Table 6]

[0038]

Examples 26 to 28 and Comparative Examples 14 to 16 The components (a), (b) and (c) shown in Table 7 were pelletized with a 30 mmφ co-rotating twin screw extruder. 25
It is extruded from a 250 mm wide T-die with a single screw extruder of mmφ to form a sheet having a thickness of about 0.75 mm.
The tensile modulus and the impact strength at 0 ° C. were measured.

[0039]

[Table 7]

[0040]

The composition obtained by blending a small amount of rubber-modified impact-resistant polystyrene with a block copolymer resin composed of a vinyl aromatic hydrocarbon and a conjugated diene has a good surface impact while maintaining the excellent transparency of the block copolymer. Significant improvement. Further, when a styrene resin is further blended, a transparent composition having a good balance between rigidity and surface impact properties can be obtained, and is suitable for housings, cases, and packaging materials in which the contents are clearly visible. It is suitable for a disposable medical material such as an artificial kidney container.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 53/02 C08L 25/04 C08L 51/04

Claims (2)

(57) [Claims] 1. A thermoplastic block copolymer comprising (a) a vinyl aromatic hydrocarbon and a conjugated diene, wherein the content of the vinyl aromatic hydrocarbon is 65% by weight or more and 85% by weight or less. Is 95% by weight or more and 99.7% by weight
The average particle diameter of the rubber particles obtained by graft-polymerizing styrene to the butadiene-based rubbery polymer is as follows:
A resin composition comprising a rubber-modified impact-resistant polystyrene having rubber particles of 5 μm or more in an amount of from 0.3% by weight to 5% by weight. 2. A thermoplastic block copolymer comprising (a) a vinyl aromatic hydrocarbon and a conjugated diene, wherein the content of the vinyl aromatic hydrocarbon is 65% by weight or more and 85% by weight or less. (B) rubber-modified impact-resistant polystyrene in which rubber particles obtained by graft-polymerizing styrene to a butadiene-based rubber-like polymer have an average particle size of 1.5 μm or more; and (c) polystyrene. A resin composition comprising at least one resin selected from vinyl aromatic hydrocarbon- (meth) acrylate copolymers, wherein (a) + (b) + (c) = 100% by weight A resin composition wherein (b) is from 0.3% by weight to 5% by weight and (c) is from 5% by weight to 70% by weight.