JPH06220278A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition having an excellent balance among a high degree of transparency, particularly freedom from a defect which gives a pale-blue appearance, rigidity, and surface impact resistance by blending a specific thermoplastic block copolymer with a vinylaromatic hydrocarbon/(meth)acrylic ester copolymer resin. CONSTITUTION:This resin composition comprises 30-70wt.% thermoplastic block copolymer and 30-70wt.% vinylaromatic hydrocarbon/(meth)acrylic ester copolymer resin having a (meth)acrylic ester unit content of 8-25wt.%. The block copolymer is the one made up of 90wt.% or more molecular chains represented by A-B-A' (wherein A and A' each is a polymer block derived from a vinylaromatic hydrocarbon and B is a block consisting of a vinylaromatic hydrocarbon/conjugated diene random copolymer and/or a conjugated diene polymer) and <=10wt.% block B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having an excellent balance of impact resistance and transparency, which is a sheet or film obtained by extrusion molding or further vacuum molding,
Containers obtained by bending, pressing, etc.,
The present invention relates to a resin composition suitable for a transparent molded product that requires high transparency and surface impact resistance such as a case.

[0002]

Block copolymer resins composed of vinyl aromatic hydrocarbons and conjugated dienes are resins having excellent transparency and impact resistance, and are widely used in sheets, films, injection molded products and the like. However, there is a trade-off relationship in that the resin that has excellent impact resistance has low rigidity, and the resin that has high rigidity has low impact resistance. In particular, both block impact resistance and surface rigidity are excellent. The actual situation is that a combined resin has not been obtained yet.

An attempt to improve the Izod impact strength as impact resistance is disclosed in Japanese Examined Patent Publication No. 52-16496. When rubber-modified polystyrene is blended in an amount of 15% or more, impact strength is improved, but transparency is significantly reduced. In addition, 0.
When the blending amount is 5%, the impact resistance, strength and rigidity are equivalent to the blending amount of 0%, and no improvement effect is recognized. Japanese Patent Office Sho 5
JP-A-9-25821 has an impact resistance composed of a rubber-modified impact-resistant styrene polymer modified with a block copolymer having a specific structure and a block copolymer comprising a vinyl aromatic hydrocarbon and a conjugated diene. And a polymer composition having good transparency is disclosed. 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 reach sufficient impact resistance.

JP-A-51-895550 discloses a transparent impact-resistant styrenic polymer composition comprising a block copolymer composed of a vinyl aromatic hydrocarbon and a conjugated diene, a rubber-modified styrene polymer and a styrene polymer. The thing is disclosed. However, no composition having satisfactory transparency and impact resistance has been found in this composition either. In recent years, from the viewpoint of protecting the global environment, the movement of replacing a resin made of chlorine as a raw material with a non-chlorine resin has become active, and a resin having an excellent overall balance of rigidity, transparency and impact resistance is desired. JP-A-4-39351 discloses a resin composition of a styrene resin (styrene homopolymer or copolymer with acrylonitrile) and a block copolymer represented by the general formula A1 -B-A2. There is. However, the block copolymer resin composition shown therein does not have sufficient impact resistance at low temperature of the block copolymer itself, and the impact resistance remarkably decreases at a temperature of 0 ° C. or less, so that the food is stored in a refrigerator or the like. It has a drawback that its use as a packaging container or use in cold regions is limited. JP-A-4-57845 discloses a composition of a styrene-based copolymer resin and a block copolymer. The block copolymer shown therein is composed of a block mainly composed of a styrene-based component and a block copolymer mainly composed of a conjugated diene, but the ratio of components constituting each block is clearly shown. However, in the examples, each block is a styrene homopolymer block. Therefore, in the case of using a block copolymer having a high vinyl aromatic hydrocarbon content among the block copolymers as in the example,
On the contrary, when a block copolymer having a low vinyl aromatic hydrocarbon content is used, impact resistance is insufficient, and not only the rigidity decreases remarkably, but also the molded product looks pale, and At present, no resin composition having an excellent overall balance of transparency and impact resistance has been obtained.

[0005]

In the extruded sheet and film which require high transparency, rigidity and surface impact resistance as described above, a high degree of transparency can be obtained in a vacuum-formed, press-formed, fold-formed container and case. To provide a resin composition having excellent balance of properties, in particular, clear transparency, rigidity and surface impact resistance, which does not appear to be pale.

[0006]

That is, the present invention is
(A) two vinyl aromatic hydrocarbon polymer blocks A,
A'and a molecular chain composed of a block B composed of a random copolymer of a vinyl aromatic hydrocarbon and a conjugated diene and / or a conjugated diene polymer sandwiched between the vinyl aromatic hydrocarbon polymer blocks. Thermoplastic block copolymer composed of 90% by weight or more of ABA 'and within 10% by weight a random copolymer of a vinyl aromatic hydrocarbon and a conjugated diene and / or a conjugated diene polymer. A thermoplastic block copolymer based on,
The vinyl aromatic hydrocarbon content in the block copolymer is 65% by weight or more and 80% by weight or less, the content of the vinyl aromatic hydrocarbon polymer block is 40% by weight or more, 55% by weight or less, vinyl aromatic The molecular weight distribution of the hydrocarbon polymer block is 1.6 or less, MI is 0.5 g / 10 min or more,
A vinyl aromatic hydrocarbon containing 20 g / 10 min or less of the thermoplastic block copolymer and (b) the (meth) acrylic acid ester content of 8% by weight or more and 25% by weight or less-
A transparent resin composition comprising a (meth) acrylic acid ester copolymer resin, wherein (a) is 30% by weight or more and 70% by weight or less with respect to (a) + (b) = 100% by weight,
(B) is a resin composition containing 30% 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 anionically polymerizing a vinyl aromatic hydrocarbon and a conjugated diene in a hydrocarbon solvent, and is a vinyl aromatic hydrocarbon containing two vinyl aromatic hydrocarbons. Of the polymer blocks A and A ′ and the block B composed of a random copolymer of one vinyl aromatic hydrocarbon and a conjugated diene and / or a conjugated diene polymer, 90% by weight of molecular chain
The above is configured.

The two vinyl aromatic hydrocarbon polymer blocks A and A'may be the same or different. 1
Block B composed of a random copolymer of vinyl aromatic hydrocarbon and conjugated diene and / or a conjugated diene polymer is a random copolymer of vinyl aromatic hydrocarbon and conjugated diene, and the distribution of each monomer is Is a block that may be uniformly random or distributed in a taper shape, or may be a stepwise distribution, and is a portion generally called a soft segment. -1 in terms of Tg
It is preferably 0 ° C or lower.

The random copolymer and / or conjugated diene polymer of vinyl aromatic hydrocarbon and conjugated diene within 10% by weight bonded to the molecular chain of ABA 'is substantially the same as block B. Is. Also, this is AB-
It may or may not be bonded to one side or both sides of the molecular chain of A ′. The block copolymer may be coupled with a coupling agent.

In any case, the vinyl aromatic hydrocarbon content in the block copolymer is 65% by weight or more and 80% by weight or less, the content of the vinyl aromatic hydrocarbon polymer block is 40% by weight or more, 55% by weight or less, the molecular weight distribution of the vinyl aromatic hydrocarbon polymer block is 1.6 or less, MI
Is 0.5 g / 10 min or more and 20 g / 10 min or less, so long as it is a thermoplastic block copolymer.

The thermoplastic block copolymer of the present invention can be represented by the following general formula. C-A-B-A'-C 'or (C-A-B-A')
-C ') n-X [In the above formula, A and A'are vinyl aromatic hydrocarbon polymer blocks, B is a random copolymer block of a vinyl aromatic hydrocarbon and a conjugated diene, and C is substantially B. Is the same as X represents a coupling agent residue or a polyanion initiator residue, and n represents an integer of 2 to 4. ] The conjugated diene constituting these block copolymers includes 1,3-
Butadiene, isoprene, 2,3-dimethyl-1,3-
Examples thereof include butadiene and 1,3-hexadiene, and these may be used alone or in combination. The content of these conjugated diene monomers in the block copolymer is 20% by weight or more and 35% by weight or less, preferably 25% by weight or more and 35% by weight or less.

The vinyl aromatic hydrocarbon constituting the block copolymer is, for example, styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, α-methylstyrene, vinylnaphthalene, vinylan. Examples thereof include tresene and 1,1-diphenylethylene. These may be used alone or in combination of two or more. When importance is attached to heat resistance, it is preferable to use 1,1-diphenylethylene together as a copolymerization monomer.

The content of vinyl aromatic hydrocarbon in the block copolymer is 65% by weight or more and 80% by weight or less, preferably 65% by weight or more and 75% by weight or less. If the vinyl aromatic hydrocarbon content is less than 65% by weight, the transparency is lowered, and if it exceeds 80% by weight, the impact resistance is lowered, which is not preferable. The content of the polymer block existing as a vinyl aromatic hydrocarbon homopolymer in the block copolymer is determined by measuring the weight of the polymer reprecipitated in methanol after decomposing the block copolymer with osmic acid. Can be measured.

The content of the vinyl aromatic hydrocarbon polymer block in the block copolymer used in the present invention is 40.
It is at least 55% by weight and at most 55% by weight. A composition using a block copolymer having a vinyl aromatic hydrocarbon homopolymer content of more than 55% by weight has excellent rigidity but low impact resistance, while the content of the homopolymer is 40% by weight. A composition using a block copolymer of less than 1 has low rigidity and low low temperature impact resistance.

The molecular weight distribution (Mw / Mn) of the polymer block existing as a vinyl aromatic hydrocarbon homopolymer in the block copolymer is the same as that of the polymer used for measuring the block ratio, that is, the block copolymer. It can be obtained by measuring GPC of a polymer re-precipitated in methanol after being decomposed with osmic acid. If this molecular weight distribution exceeds 1.6, the anisotropy of the sheet becomes remarkable and the sheet is easily cracked in the extrusion direction, which is not preferable. In order to control the molecular weight distribution of the vinyl aromatic hydrocarbon homopolymer existing in the block copolymer to be small, the amount of vinyl aromatic hydrocarbon added to form A block and A'block in the case of the sequential polymerization method It is possible to adjust appropriately. Further, in the polymerization method described below, it can be adjusted by the kind and addition method of the initiator, the blending amount of the polar compound, the combined use of the polymerization terminator and the like.

These block copolymers can be produced by a known polymerization technique, for example, in a hydrocarbon solvent such as n-hexane, cyclohexane or toluene, in which organic lithium compounds or organic sodium compounds such as n-butyllithium, sec-butyllithium, Polymerization can be performed by a method of sequentially adding monomers using butadienyldilithium as an initiator, or the polymerization is completed by coupling with a polyfunctional coupling agent such as a polyhalogen compound or a polyepoxy compound. Then, it can be obtained by adding alcohol or water to stop the polymerization and removing the solvent. Further, in order to control the polymerization rate and molecular weight distribution, the microstructure such as the vinyl structure of the conjugated diene portion in the polymer, an appropriate amount of an ether compound such as tetrahydrofuran or tetramethylethylenediamine, a polar compound represented by an amine compound is added. It can also be polymerized.

The molecular weight of the block copolymer is such that MI (G condition) is 0.5 g / min or more and 20 g / 10 min or less, preferably 1 to 10 g / 10 min.
If it is less than 0.5 g / 10 min, the workability is poor, and 20 g /
If it exceeds 10 min, the strength of the product is lowered, which is not preferable. Examples of the monomer constituting the vinyl aromatic hydrocarbon- (meth) acrylic acid ester copolymer as the component (b) include the following. Vinyl aromatic hydrocarbons include styrene, α-methylstyrene, p-methylstyrene, p
Examples of the (meth) acrylic acid ester include methacrylic acid methyl ester, ethyl ester, n-butyl ester, i-butyl ester, and t-butyl styrene.
-Butyl ester, 2-ethylhexyl ester, methyl ester of acrylic acid, ethyl ester, n-butyl ester, 2-ethylhexyl ester, (meth)
It is an ester of acrylic acid and an alcohol having 1 to 8 carbon atoms.

Among these polymers as the component (b), a styrene-n-butyl acrylate copolymer is preferable in order to maintain high transparency and rigidity and at the same time improve processability. A styrene-methyl methacrylate copolymer is preferable for improving the rigidity and heat resistance, but if it is blended in a large amount, the transparency becomes slightly inferior. In the styrene-methyl methacrylate copolymer and the styrene-n-butyl acrylate copolymer, the copolymerization composition ratio of methyl methacrylate or butyl acrylate is 8 to 25% by weight, preferably 10 because of the transparency of the final composition. Is about 23% by weight, but 0.1
It may contain 2% of other monomers. The MI (G) of these vinyl aromatic hydrocarbon- (meth) acrylic acid ester copolymers is preferably 1 to 10 g / 10 min.

The resin composition of the present invention has transparency, rigidity,
If necessary, various additives may be added as long as the impact resistance is not impaired. These additives include block copolymer elastomers of vinyl aromatic hydrocarbons having a vinyl aromatic hydrocarbon content of 50% by weight or less and conjugated dienes, rubber-modified impact-resistant polystyrene, non-rubber-modified polystyrene, polyethylene terephthalate, Antioxidants, antistatic agents, antifogging agents, ultraviolet absorbers, lubricants, colorants, mineral oils, plasticizers, etc.

The rubber-modified impact-resistant polystyrene was grafted by dissolving the butadiene rubber-like polymer in styrene and then initiating the polymerization of styrene, and then polymerizing under the condition that styrene was graft-polymerized to the rubber-like polymer. A rubber-modified impact-resistant polystyrene in which the average particle size of the rubber particles formed by the rubber-like polymer is 1.5 μm or more is preferable.

The term "average particle size" as used herein means a transmission electron microscope photograph of rubber-modified impact-resistant polystyrene by an ultrathin section method, and the particle size of about 500 rubber particles in the photograph is measured to obtain the average. The particle diameter is calculated by ΣniDi ⁴ / ΣniDi ³ . (Here, ni is the number of particles in which the major axis of the rubber particles is Di.) These rubber particles have a so-called salami structure or a core-shell structure in which a polystyrene part is incorporated.

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

The rubber-like 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 enhancing impact resistance, and styrene-butadiene copolymer obtained by copolymerizing styrene is preferable for transparency. The blending amount of the rubber-modified impact-resistant polystyrene blended in the transparent resin composition of the present invention is within a range that does not impair the original transparency of the block copolymer, but the haze value is 3% in the thickness of the final product.
The following are preferred. The specific amount of rubber-modified impact-resistant polystyrene compounded is 0.5 in the block copolymer composition.
At least 8% by weight, preferably at least 1% by weight,
Used up to 5% by weight.

When the content of the rubber-modified impact-resistant polystyrene is less than 0.5% by weight, the transparency is good, but the effect of improving the impact resistance is small, and when it exceeds 8% by weight, the impact resistance is improved. However, the transparency of the product becomes extremely poor. The block copolymer elastomer of vinyl aromatic hydrocarbon having a vinyl aromatic hydrocarbon content of 50% by weight or less and a conjugated diene is used to improve impact resistance at low temperature, but it has poor transparency and rigidity. It can be used within the range not touched. The preferred blending amount is 3% by weight or more and 15% by weight or less, more preferably 5% by weight or more and 10% by weight or less in the block copolymer composition.

[0025]

EXAMPLES Examples of the present invention will be described below, but these do not limit the scope of the present invention. Preparation of Block Copolymer of Component (a) The block copolymers A-1 to A-12 in Table 1 are prepared by using n-butyllithium as an initiator in a cyclohexane solvent and using styrene, a styrene-butadiene mixture, and styrene. A cyclohexane solution of a monomer was added in order to perform polymerization, and the polymerization was stopped with methanol, followed by 2- (2-hydroxy-3).
-T-butyl-5-methylbenzyl) -4-methyl-6
-T-Butylphenyl acrylate and trisnonylphenyl phosphite were added by 0.5 parts each as a stabilizer to 100 parts of the block copolymer, and the solvent was distilled off. The content of block polystyrene was measured by decomposing the block copolymer with osmic acid and then reprecipitating it in methanol. Also, the block styrene GP
From C peak to block styrene molecular weight distribution Mw / Mn
I asked. Melt flow (MI) was measured under G conditions.
The block polymer A-11 contains about twice as many monomers as A '.
Polymerization was carried out by adding to a portion. Block copolymer A-12
Is a block copolymer having a C-A-B-A 'structure, and was polymerized by adding a monomer so that the polybutadiene portion C occupies 13% by weight of the block polymer.

[0026]

[Table 1]

Production of Component (b) The component (b) used in Table 2 is shown below. B-1 was a commercially available product, and B-2 and B-3 were obtained by radical polymerization.

[0028]

[Table 2]

Production of Rubber-Modified Impact-Resistant Polystyrene The rubber-modified impact-resistant polystyrene of Table 3 was prepared by dissolving the rubber shown in Table 3 in styrene monomer and polymerizing it in a reaction vessel equipped with a stirring blade to obtain an unreacted product. It was obtained by removing monomers and the like under reduced pressure. The average particle diameter of the rubber particles was adjusted by changing the rotation speed of the stirring blade.

[0030]

[Table 3]

The evaluation method is as follows. [Transparency] The haze value was measured according to JIS K6714. A 1/8 inch radius was used. [Impactability] Impact resistance is measured with a falling weight type graphic impact tester manufactured by Toyo Seiki Co., Ltd.
The energy [J] until the sheet breaks was obtained by changing the measurement temperature using an inch. [Tensile Elastic Modulus] In accordance with JIS K7113, the extruding direction of the sheet and the direction perpendicular to the extruding direction were measured. A material having a large ratio of the tensile elastic modulus in the extrusion direction to the vertical direction is not preferable because of large anisotropy.

[0032]

Examples 1 to 6 and Comparative Examples 1 to 8 Components (a) and (b) shown in Table 4, Table 5 and Table 6 were pelletized by a 30 mmφ co-rotating twin-screw extruder, and then the compositions were prepared. 25 mmφ
Was extruded from a T-die having a width of 250 mm to form a sheet having a thickness of about 0.75 mm, and the haze value, the tensile elastic modulus, and the impact strength were measured.

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

[Table 6]

In the table, compounding amount, total styrene amount, block styrene content is% by weight, sheet thickness is mm, haze value is%,
The tensile modulus was expressed in Kgf / mm ² , and the surface impact strength was expressed in joules. Regarding the sheet anisotropy, those that are difficult to crack in the extrusion direction are represented by O, and those that are easily cracked are represented by X.

[0037]

Examples 7 and 8 and Comparative Examples 9 and 10 Components (a) and (b) shown in Table 7 were molded into a sheet having a thickness of about 0.75 mm in the same manner as in Example 1, and the haze value and the tensile strength were measured. The elastic modulus and impact strength were measured.

[0038]

[Table 7]

[0039]

Examples 9 to 12 and Comparative Example 11 (a) shown in Table 8
Component 1, component (b), component (c), and component (d) were used in Example 1
A sheet having a thickness of about 0.75 mm was formed by the same method as described above, and the haze value, tensile modulus, and impact strength were measured.

[0040]

[Table 8]

[0041]

The composition of the thermoplastic block copolymer resin having a specific structure composed of vinyl aromatic hydrocarbon and conjugated diene and the copolymer resin of vinyl aromatic hydrocarbon and (meth) acrylic acid ester is , The original transparency of the block copolymer is maintained, and the rigidity is high, -1
It has the property of having a low temperature surface impact property at a temperature of 0 ° C or lower. Further, when a small amount of rubber-modified impact-resistant polystyrene or a vinyl aromatic hydrocarbon having a vinyl aromatic hydrocarbon content of 50% by weight or less and a block copolymer elastomer of a conjugated diene is blended, the surface impact property at a low temperature is further improved. A composition having a good balance of rigidity and transparency can be obtained, and it is suitable for cases and packaging materials for food applications where the content looks vivid.

[Procedure amendment]

[Submission date] April 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Conjugated dienes constituting these block copolymers include 1,3-butadiene, isoprene and 2,3.
-Dimethyl-1,3-butadiene, 1,3-hexadiene, etc. may be mentioned, and these may be used alone or in combination. The content of these conjugated diene monomers in the block copolymer is 20% by weight or more and 35% by weight or less, preferably 25% by weight or more and 35% by weight or less.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

The evaluation method is as follows . [Transparency] The haze value was measured according to JIS K6714. [Impactability] The impact resistance was determined by using a falling weight type graphic impact tester manufactured by Toyo Seiki Seisaku-sho, Ltd. with a 1-inch diameter of the impact core, and changing the measurement temperature to determine the energy [J] until the sheet breaks. [Tensile Elastic Modulus] According to JIS K 6872 , measurement was made in the sheet extrusion direction and the direction perpendicular to the extrusion direction. A material having a large ratio of the tensile elastic modulus in the extrusion direction to the vertical direction is not preferable because of large anisotropy.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

[0040]

[Table 8]

Claims (1)

[Claims] 1. (a) Two vinyl aromatic hydrocarbon polymer blocks A and A ', and a random copolymer of a vinyl aromatic hydrocarbon and a conjugated diene sandwiched between the vinyl aromatic hydrocarbon polymer blocks. Molecular chain A-B composed of block B composed of polymer and / or conjugated diene polymer
-A 'is 90% by weight or more, and 10% or less by weight is a random copolymer of vinyl aromatic hydrocarbon and conjugated diene and / or a thermoplastic block copolymer composed of a conjugated diene polymer. A thermoplastic block copolymer having a vinyl aromatic hydrocarbon content of 65% by weight or more and 80% by weight or less, and a vinyl aromatic hydrocarbon polymer block content of 40% by weight. %
As described above, 55% by weight or less, the molecular weight distribution of the vinyl aromatic hydrocarbon polymer block is 1.6 or less, and the MI is 0.5 g / 1.
Vinyl aromatic hydrocarbon- (meth) acrylic acid having a content of the thermoplastic block copolymer of 0 min or more and 20 g / 10 min or less and (b) (meth) acrylic acid ester of 8% by weight or more and 25% by weight or less A transparent resin composition comprising an ester copolymer resin, wherein (a) + (b) = 1
A resin composition in which (a) is 30% by weight or more and 70% by weight or less and (b) is 30% by weight or more and 70% by weight or less with respect to 00% by weight.