JPH0717809B2 - Block copolymer resin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention provides a molded article which is excellent in transparency and impact resistance and has less warpage in injection molding applications, and has mutual dispersibility in extrusion molding applications of blended products with polystyrene. The present invention relates to a block copolymer resin composition which gives a good molded article with few flow marks.

[0002]

2. Description of the Related Art A block copolymer composed of a conjugated diene and a vinyl aromatic hydrocarbon is a thermoplastic resin having excellent transparency when the content of the vinyl aromatic hydrocarbon is relatively high, and having a better impact resistance than polystyrene. In recent years, the amount of its use has been increasing mainly in the fields of food packaging containers, daily sundries, toys, light electric parts and the like.

As a method for producing such a block copolymer, Japanese Patent Publication No. 36-19286 and Japanese Patent Publication No. 43-1 are available.
No. 7,979, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 57-49567, Japanese Patent Publication No. 58-11446. In addition, such a block copolymer is blended with polystyrene for the purpose of improving rigidity,
On the contrary, a block copolymer may be blended for the purpose of improving the impact resistance of polystyrene. Examples of the method for producing such a composition include JP-B-45-19388, JP-B-47-43618, JP-B-51-27701, JP-B-52-32774, and JP-B-53-41.
Publication No. 7 is cited.

[0004]

However, the block copolymers disclosed in these methods do not have sufficient dart impact strength in injection-molded articles, and improvement thereof is desired. Moreover, since injection molding is performed under high shear, anisotropy is likely to occur in the molded product, and problems such as weak strength in a certain direction and warpage of the molded product are likely to occur. Particularly in a large-sized molded product or a flat plate, since a warp is likely to occur, a material having a small warp is desired. Furthermore, in extrusion molding applications of blends with polystyrene, flow marks and delamination phenomena due to poor mutual dispersion are observed, resulting in a problem of significantly impairing the appearance of molded articles.

[0005]

Under these circumstances, the present inventors have excellent impact resistance in extrusion molding of blends with vinyl aromatic hydrocarbon polymers such as polystyrene, and flow marks due to mutual dispersion failure. As a result of further studies on obtaining a block copolymer resin composition that does not cause a layer delamination phenomenon, a specific amount of a conjugated diene homopolymer block at one end or both ends of the block copolymer used in the present invention and And / or having a copolymer block of a vinyl aromatic hydrocarbon and a conjugated diene, and at the same time, setting the molecular weight distribution of the vinyl aromatic hydrocarbon polymer incorporated in the block copolymer to a certain range. As a result, they have found that the object is achieved, and completed the present invention.

That is, the present invention has a polymer structure represented by the general formula B-A-B'-A, B-A-B'-A-B'-A B-A-B'-A-B, B-A-. B'-A-B'-A
-B (In the above formula, A is a vinyl aromatic hydrocarbon polymer block, and B and B'are polymer blocks and / or conjugated dienes of a conjugated diene containing 30% by weight or more of a conjugated diene and a vinyl aromatic hydrocarbon. It is a homopolymer block.), The weight ratio of vinyl aromatic hydrocarbon and conjugated diene is 60/40 to 95/5, and the melt flow index measured under G condition is 0. 1-100g
In the block copolymer of / 10 min, (1)
The block copolymer is oxidatively decomposed using osmium tetroxide as a catalyst, and the ratio of the weight average molecular weight to the number average molecular weight of the vinyl aromatic hydrocarbon polymer block obtained by GPC measurement is 1.2 to 2.0. (2) The block ratio of vinyl aromatic hydrocarbon in the block copolymer is 50 to 80.
%, And (3) the vinyl aromatic hydrocarbon content in the BA segment present at the terminal of the block copolymer is 75 to 97% by weight, and (4) present at the terminal of the block copolymer. The total amount of B block is 5 to 15% by weight of the block copolymer, which is a resin composition comprising a block copolymer and a styrene polymer.

The present invention will be described in detail below. The block copolymer used in the present invention has a polymer structure having the above general formula. The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 60/40 to 95/5, preferably 65/3.
It is a block copolymer of 0 to 90/10. If the vinyl aromatic hydrocarbon content is less than 60% by weight, the rigidity and
The transparency is poor, and when it exceeds 95% by weight, impact resistance is poor, which is not preferable. In the present invention, the vinyl aromatic hydrocarbon content in the B block and B'block is 7
From the viewpoint of low temperature characteristics, it is preferably less than 5% by weight, preferably 60% by weight or less. When a random copolymer portion of the B block and B'block conjugated dienes and the vinyl aromatic hydrocarbon is present, even if the vinyl aromatic hydrocarbon in the portion is evenly distributed along the polymer chain,
Further, it may be distributed in a taper shape.

The characteristics of the block copolymer used in the present invention are that the weight average molecular weight (hereinafter referred to as Mw) and number of the vinyl aromatic hydrocarbon polymer block in the block copolymer measured by the analysis method described later. Average molecular weight (hereinafter Mn
Ratio) is 1.2 to 2.0, preferably 1.3 to
It is in the range of 1.8 and the vinyl aromatic hydrocarbon content in the BA segment is 75 to 97% by weight, preferably 80 to 95% by weight. Further, the total amount of the B block existing at the terminal of the block copolymer is 5 to 15 polymer% of the block copolymer. If Mw / Mn is less than 1.2, the impact resistance is poor, and if it exceeds 2.0, molding anisotropy occurs during injection molding, which causes a problem that the molded product warps or causes poor dispersion and causes a delamination phenomenon. It is not preferable because it will occur.

The method of controlling the Mw / Mn of the vinyl aromatic hydrocarbon polymer block A is such that when polymerizing different blocks A in the molecular chain of the block copolymer, the monomer feed amount is changed to obtain different number average molecular weights. Block A
The method in which is present in the same molecular chain is preferable from the economical point of view. Also, vinyl aromatic hydrocarbon polymer block A
The number average molecular weight of is required to be 3000 or more in order to exert the performance as a block.

Further, when the vinyl aromatic hydrocarbon content in the B-A segment is less than 75% by weight, poor dispersion occurs, and when it exceeds 97% by weight, impact resistance is lowered, which is not preferable. The Mw / Mn of the vinyl aromatic hydrocarbon polymer block can be measured as follows. A vinyl aromatic hydrocarbon polymer component (LM KOLTHOFFOFF) obtained by oxidatively decomposing a block copolymer with di-tert-butyl hydroperoxide using osmium tetroxide as a catalyst and then adding methanol to the decomposed product. .Et
al. J. Polym. sci. 1,429 (194
The method described in 6)) is measured by gel permeation chromatography (GPC), and the value is calculated according to a conventional method (for example, the method described in “Gel chromatography <Basic edition>” published by Kodansha). As the calibration curve for GPC, one prepared using standard polystyrene commercially available for GPC is used.

The number average molecular weight of the vinyl aromatic hydrocarbon polymer block which can be analyzed by this method is about 3000 or more. The B block of the block copolymer of the present invention,
The B'block and the B'block are polymerized by sufficiently controlling the monomer composition, so that there is no vinyl aromatic hydrocarbon polymer having a number average molecular weight of 3000 or more in the block.

In the present invention, a particularly preferable block copolymer from the viewpoint of impact resistance is a vinyl aromatic hydrocarbon / conjugated diene weight ratio of 65/35 to 85/15 and a block of vinyl aromatic hydrocarbon. 50-88% by weight,
The block copolymer is preferably 65 to 85% by weight. Here, the block ratio of vinyl aromatic hydrocarbons means that the amount of the block copolymer component is quantified by the oxidative decomposition method described above, and the amount of the vinyl aromatic hydrocarbons contained in the block copolymer is determined. The value (percentage) divided by the amount.

The molecular weight of the block copolymer used in the present invention can be arbitrarily adjusted depending on the amount of the catalyst used for polymerization.
The melt flow index (JIS
Measured by K-6870. Condition is G condition and temperature is 200
C., weight 5 kg) is 0.1 to 100 g / 10 min, preferably 1 to 50 g / 10 min. The block copolymer used in the present invention is obtained by polymerizing in a hydrocarbon solvent with an organolithium compound as an initiator.

As the hydrocarbon solvent, butane, pentane,
Aliphatic hydrocarbons such as hexane, isopentane, heptane, octane, isooctane; Alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane; and aromatics such as benzene, toluene, ethylbenzene, xylene Hydrocarbons can be used. The organolithium compound is an organolithium compound having one or more lithium atoms bonded in the molecule, and examples thereof include ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, Hexamethylenedilithium, butadienyldilithium, isoprenyldilithium and the like can be mentioned.

In the present invention, examples of vinyl aromatic hydrocarbons are styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene,
There are vinyl anthracene and the like, but styrene is particularly common. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds,
For example, 1.3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-
Examples of butadiene, 1,3-pentadiene, 1,3-hexadiene, etc.
Butadiene and isoprene may be mentioned. These may be used alone or in combination of two or more.

In producing the block copolymer used in the present invention, as a method for adjusting the block ratio of vinyl aromatic hydrocarbon, (i) continuously polymerizing a mixture of vinyl aromatic hydrocarbon and conjugated diene. It is recommended to feed the system to polymerize and / or (ii) use a polar compound or a randomizing agent to copolymerize the vinyl aromatic hydrocarbon with the conjugated diene. Examples of polar compounds and randomizing agents include tetrahydrofuran, diethylene glycol dimethyl ether, ethers such as diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, potassium and sodium salts. Examples include alkoxides.

The block copolymer used in the present invention is a block copolymer of a vinyl aromatic hydrocarbon having a vinyl aromatic hydrocarbon content outside the range specified by the present invention of 60 to 95% by weight and a conjugated diene. Resin, block copolymer elastomer of vinyl aromatic hydrocarbon containing less than 60% by weight of vinyl aromatic hydrocarbon and conjugated diene, polymer of vinyl aromatic hydrocarbon monomer, vinyl aromatic carbon Copolymers of hydrogen-based monomers with other vinyl monomers such as ethylene, propylene, butylene, vinyl chloride, vinylidene chloride, vinyl acetate, acrylates such as methyl acrylate; methacrylates such as methyl methacrylate; acrylonitrile, etc. , At least one polymer selected from rubber-modified styrene resin (HIPS), etc. And impact resistance can be improved.

As the other thermoplastic polymer to be blended with the block copolymer used in the present invention, a styrene-based polymer is particularly preferable, and as such a polymer, a non-rubber-modified styrene-based polymer and a rubber-modified styrene-based polymer can be used. can give. The non-rubber-modified styrene polymer is obtained by polymerizing the vinyl aromatic hydrocarbon compound or a monomer copolymerizable therewith. Examples of the monomer copolymerizable with the vinyl aromatic hydrocarbon compound include α-methylstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, and maleic anhydride.

Particularly preferred non-rubber-modified styrene-based polymers are polystyrene, styrene-α-methylstyrene copolymer, acrylonitrile-styrene copolymer, styrene-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescing, and these can be used alone or as a mixture of two or more kinds. The rubber-modified styrenic polymer that can be used in the present invention is obtained by polymerizing a vinyl aromatic hydrocarbon compound or a mixture of a monomer copolymerizable therewith and an elastomer, and the polymerization method includes suspension polymerization and emulsion polymerization. Bulk polymerization, bulk-suspension polymerization and the like are generally performed. Examples of the monomer copolymerizable with the vinyl aromatic hydrocarbon compound include α-methylstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, and maleic anhydride. As the elastomer, natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-
Butadiene rubber, high styrene rubber, polybutadiene rubber, chloroprene rubber, polybutene rubber, rubber-like ethylene-propylene copolymer, rubber-like butadiene-acrylonitrile copolymer, butyl rubber, various nitrile rubbers,
A rubber-like ethylene-vinyl acetate copolymer, a rubber-like ethylene-acrylic acid ester copolymer, a rubber-like atactic polypropylene resin, a rubber-like ethylene-acrylic acid ionomer and the like are used.

These elastomers include vinyl aromatic hydrocarbon compounds or monomers 10 copolymerizable therewith.
2 to 70 parts by weight, more usually 3 to 50 parts by weight, relative to 0 parts by weight, is dissolved in the monomer or is used as a latex for bulk polymerization, bulk-suspension polymerization, emulsion polymerization and the like. As a particularly preferable rubber-modified styrene-based polymer,
Impact resistant rubber modified styrene polymer, acrylonitrile-
Butadiene-styrene copolymer, acrylate-butadiene-styrene copolymer, methacrylic acid ester-
Examples thereof include a butadiene-styrene copolymer and an impact-resistant rubber-modified styrene-maleic anhydride copolymer, and these can be used alone or as a mixture of two or more kinds.

In the composition of the block copolymer used in the present invention and the styrene-based polymer, the compounding amount of the styrene-based polymer can be variously changed according to the characteristics of the intended composition. For example, in the composition of the block copolymer and the non-rubber-modified styrene-based polymer, the mutual composition of the block copolymer and the non-rubber-modified styrene-based polymer is improved in order to improve the rigidity of the block copolymer and the impact resistance of the non-rubber-modified styrene-based polymer. Blending weight ratio is 95/5
It can be used at 5 to 95, preferably 90/10 to 10/90. When a rubber-modified styrene-based polymer is used and the surface properties and impact resistance of the block copolymer are improved, the compounding weight ratio of the block-copolymer and the rubber-modified styrene-based polymer is 99. 9 / 0.1-50 /
When used in the range of 50, on the other hand, when improving the gloss and colorability of the rubber-modified styrenic polymer, the compounding weight ratio of the block copolymer and the rubber-modified styrenic polymer is 50/50.
Used in the range of ~ 3/97. If necessary, a non-rubber-modified styrene-based polymer and a rubber-modified styrene-based polymer may be used in combination as the styrene-based polymer.

The block copolymer resin composition of the present invention comprises
If desired, any additive can be included. The type of additive is not particularly limited as long as it is commonly used for compounding plastics, for example, inorganic reinforcing agents such as glass fiber, glass beads, silica, calcium carbonate, talc, organic fiber, coumarone indene resin, etc. Organic reinforcing agents, organic peroxides, inorganic peroxides and other cross-linking agents, titanium white, carbon black, iron oxide and other pigments, dyes,
Examples include flame retardants, antioxidants, ultraviolet absorbers, antiblocking agents, antistatic agents, lubricants, plasticizers, other extenders, and mixtures thereof. Specifically, "Practical Handbook of Additives for Plastics and Rubbers" (Chemical Industry Co., Ltd.)
The compounds described in 1. can be used.

The block copolymer resin composition of the present invention comprises
It can be produced by any conventionally known compounding method. For example, an open roll, an intensive mixer, an internal mixer, a co-kneader, a continuous kneader with a twin-screw rotor, a melt-kneading method using a general kneader such as an extruder, each component is dissolved or dispersed in a solvent and then mixed with a solvent. And the like are used.

The block copolymer resin composition of the present invention comprises
Since it is transparent and has excellent impact resistance, it can be suitably used as a material for injection molding. In particular, since there is little warpage when injection-molded, it is suitable for flat plate-shaped products, molded products with many flat plate-shaped portions, and large-sized molded products. The injection-molded product of the block copolymer resin composition of the present invention is used for various applications in which a general-purpose thermoplastic resin injection-molded product is used, such as in the fields of toys, daily necessities, food containers, miscellaneous goods, and light electrical components. can do. In addition, the block copolymer resin composition of the present invention may be formed by any other conventionally known molding method such as extrusion molding and blow molding to obtain a sheet, a film, a foam, a blow molded article of various shapes, a pressure molded article, and a vacuum. Molded products, uniaxially stretched molded products,
Can be easily molded into a wide variety of practically useful products such as biaxially stretched molded products, specifically in a wide range of container packaging materials such as food container packaging, blister packaging, fruit and fruit packaging films It can also be used.

[0025]

EXAMPLES In order to describe the present invention in more detail, examples of the present invention will be shown below, but it goes without saying that the contents of the present invention are not limited to these examples.

[0026]

[Reference Examples 1 to 5] The autoclave was internally purged with nitrogen gas, then 5 liters of purified and dried cyclohexane were charged, and then the mixture was stirred and heated to 70 ° C. Next, n-butyllithium was added as a catalyst. The amount of addition is M.M. of the block copolymer. The I was adjusted so as to have the predetermined numerical value shown in Table 2. Next, purified and dried butadiene and / or styrene monomer was added by a plunger pump under the conditions shown in Table 1 in the amount of monomer and the feeding time, and the polymerization was continued. After completion of the polymerization in a predetermined polymerization step, 2 ml of methanol was added to terminate the polymerization, and 10 g of 4-methyl-2.6-di-tert-butylphenol was added as an antioxidant. The obtained block copolymer was pelletized with an extruder, and then IS-8 manufactured by Toshiba Machine Co., Ltd.
0A (50 ounce injection molding machine) at 200 ° C, thickness 3
mm plate was injection molded.

Table 2 shows the physical properties of the obtained injection molded product.
The block copolymer within the scope of the present invention was a molded product having excellent transparency, impact resistance and rigidity, and having no warp. Table 2
The Mw / Mn of the polystyrene block and the block ratio of styrene are vinyl aromatic carbons precipitated by oxidative decomposition with di-tert-butyl hydroperoxide using osmium tetroxide as a catalyst and then adding methanol to the decomposed product. The weight of the hydrogen polymer component was measured, and the gel permeation chromatography was measured and calculated. The styrene content of the B-A segment was calculated from the amount of monomer added during the polymerization.

Further, a styrene-butadiene copolymer block constituting the block copolymer (B in the claims)
Or it corresponds to B '. When the content of butadiene in) is calculated, for example, the weight ratio of butadiene / styrene of B ₁ or B ₄ in block copolymer B or D in Table ₁ is 20/40. The content of butadiene in each styrene-butadiene copolymer block was 33.3% by weight.

[0029]

[Table 1]

[0030]

[Table 2]

However, (Note) in Table 2 is as follows. (Note 1) Compliant with ASTM D-1709 (Note 2) Compliant with ASTM D-790 (Note 3) Compliant with JIS K-6714 (Note 4) Warpage of the injection molded product is the flow direction of the molded product and the direction perpendicular to it. Has a large relationship with the difference in molding shrinkage in
The larger the difference is, the larger the warp of the injection-molded article is.

Ranks were classified as follows according to the difference in molding shrinkage. 0.2% or less ◎ 0.2% or more and 0.4% or less ○ 0.4% or more and 0.6% or less △ More than 0.6% × Incidentally, the molding shrinkage in the direction perpendicular to the flow direction is The molding shrinkage on the side opposite to the gate side was measured.

[0033]

[Reference Comparative Examples 1 to 6] The autoclave was internally replaced with nitrogen gas, then 5 liters of purified and dried cyclohexane were charged, and then the mixture was stirred and heated to 70 ° C. Next, n-butyllithium was added as a catalyst. The addition amount was adjusted so that the block copolymer had the predetermined numerical values shown in Table 4.

Next, 1.5 g of tetrahydrofuran was added, and a mixed monomer of butadiene and styrene purified and dried under the conditions shown in Table 3 was added by a plunger pump to polymerize the styrene monomer. Polymerization was carried out by adding under pressure within 2 minutes to the autoclave. After completion of the polymerization in a predetermined polymerization step, 2 ml of methanol was added to stop the polymerization, and 10 g of 4-methyl-2.6-di-tert-butylphenol was added as an antioxidant. The obtained block copolymer was injection-molded by the same method as in Reference Examples 1-5. Table 4 shows the physical properties of the obtained injection molded product. Molded products of block copolymers outside the scope of the present invention had a poor balance between impact resistance and rigidity.

If the Mw / Mn exceeds the range of the present invention, the molded product is warped and the appearance is poor.

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Examples 1 and 2, Comparative Examples 1 to 4] 60% by weight of the same block copolymer as used in Reference Examples 1 and 5 and Reference Comparative Examples 1 to 4 and 40% by weight of Stylon 685 were mixed, respectively. And a sheet extruder having a thickness of 0.7 mm was obtained. Further, this sheet was vacuum-molded to check the compatibility between polystyrene and the block copolymer. Table 5 shows the sheet physical properties of the obtained block copolymer resin compositions. It is clear that the molded product of the block copolymer resin composition within the scope of the present invention is transparent, has excellent dispersibility, and has a particularly good balance of rigidity and impact resistance.

[0039]

[Table 5]

[0040]

EFFECTS OF THE INVENTION The block copolymer resin composition of the present invention is transparent and has excellent impact resistance, so that it can be suitably used as a material for injection molding. In particular, since there is little warpage when injection-molded, it is suitable for flat plate-shaped products, molded products with many flat plate-shaped portions, and large-sized molded products. In addition, the block copolymer resin composition of the present invention is another conventionally known molding method, for example,
By extrusion molding, blow molding, etc., it can be easily molded into sheets, films, foams, hollow molded products of various shapes, compressed air molded products, vacuum molded products, uniaxially stretched molded products, biaxially stretched molded products and the like.

Claims (1)

[Claims] 1. A polymer structure of (A) has the general formula B-A-B'-A, B-A-B'-A-B, B-A-B'-A-B'-A, B-A. -B'-A-B'-AB, (wherein A is a vinyl aromatic hydrocarbon polymer block, B and B'are conjugated diene and vinyl aromatic containing 30% by weight or more of conjugated diene) It is a copolymer block with a hydrocarbon and / or a conjugated diene homopolymer block), and the weight ratio of the vinyl aromatic hydrocarbon and the conjugated diene is 60/40 to 95/5. Yes,
Melt flow index measured under G condition is 0.1
In a block copolymer of 100 g / 10 min, (1) the weight average molecular weight and number of the vinyl aromatic hydrocarbon polymer block obtained by subjecting the block copolymer to oxidative decomposition using osmium tetroxide as a catalyst and GPC measurement. The ratio to the average molecular weight is 1.2 to 2.0, (2) the block ratio of the vinyl aromatic hydrocarbon in the block copolymer is 50 to 88%, and (3) the end of the block copolymer. The vinyl aromatic hydrocarbon content in the B-A segment present in the block copolymer is 75 to 97% by weight, and (4) the total amount of the B blocks present at the terminal of the block copolymer is 5 to 15% of that of the block copolymer. A resin composition comprising (B) a styrene-based polymer and a block copolymer characterized by being in a weight percentage.