JPH0633328B2 - Method for producing block copolymer resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a block copolymer resin for injection molding, which is excellent in transparency, impact resistance and surface hardness and gives a molded article with little warpage.

[Conventional technology]

A block copolymer composed of a conjugated diene and a vinyl aromatic hydrocarbon has excellent transparency when a relatively high vinyl aromatic hydrocarbon content is obtained, and a thermoplastic resin having better impact resistance than polystyrene can be obtained. In recent years, its usage has been increasing mainly in fields such as food packaging containers, daily sundries, toys, and light electric parts.

Examples of the method for producing such a block copolymer include JP-B-36-19286, JP-B-43-17979, JP-B-48-2423 and JP-B-57-495.
67 and Japanese Patent Publication No. 58-11446.

[Problems to be solved by the invention]

However, the block copolymers specifically disclosed in these methods are not sufficient in impact resistance, especially the dirt impact resistance of injection molded articles, and improvement thereof is desired. Also, since injection molding is performed under high shear, anisotropy is likely to occur in the molded product, and the strength becomes weak in one direction,
It is easy to cause problems such as warping of molded products. In particular, since warpage is likely to occur in forming a large-sized molded product or a flat plate, a material having less warpage is desired. Further, in injection molding, a material having a good surface hardness and being hard to be scratched is desired, but with the conventional block copolymer resin, when the surface hardness is improved, there is a problem that the impact resistance is lowered.

Under these circumstances, the present inventors have advanced the study on obtaining a molded article having excellent impact resistance and surface hardness and less warpage, and as a result, the vinyl aromatic hydrocarbon polymer incorporated in the block copolymer. It was found that the object can be achieved by setting the molecular weight distribution of the components in a specific range and adjusting the vinyl aromatic hydrocarbon content and the vinyl aromatic hydrocarbon block ratio, and completed the present invention. It was.

[Means for Solving the Problems]

That is, in the present invention, the polymer structure is represented by the general formula (A) A ₁ -B ₁ -A ₂ (B) B ₁ -A ₁ -B ₂ -A ₂ (C) A ₁ -B ₁ -A ₂ -B. linear block copolymer represented by ₂ -A _3, or the general formula _{(d) (A 1 -B 1 -A 2} ) m + 2 -X ( _{e) (A 1 -B 1 -A 2} -B 2) Radial block copolymer represented by _{m + 2-} X, (wherein A is a random copolymer part of a conjugated diene and a vinyl aromatic hydrocarbon and a vinyl aromatic hydrocarbon polymer part, and is a vinyl aromatic compound). A polymer segment having a content of a group hydrocarbon of 50% by weight or more or a polymer segment composed only of a vinyl aromatic hydrocarbon homopolymer portion is shown, and B represents a conjugated diene and a vinyl aromatic hydrocarbon. Random copolymer moiety and / or co-polymer Denotes a polymer segment composed of the part diene polymer portion and having a vinyl aromatic hydrocarbon content of less than 50% by weight.
Is an integer of 1 to 5. X represents a residue of the coupling agent or a residue of the initiator of the polyfunctional organolithium compound. (I) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 65/35 to 85/15, and the block ratio of vinyl aromatic hydrocarbon is 88% by weight. Or a vinyl aromatic hydrocarbon to conjugated diene weight ratio of 75 /
25 to 95/5, the block ratio of vinyl aromatic hydrocarbon is 70 to 80% by weight, and (ii) the ratio of the weight average molecular weight to the number average molecular weight of the vinyl aromatic hydrocarbon polymer component is 1.2. Is 2.0, and (iii) Melt flow index (measured by JIS K-6870. Conditions are G condition, temperature 200 ° C., weight 5 kg) is 2
50 g / 10 min. When the block copolymer resin is a hydrocarbon solvent using an organolithium compound as an initiator, the block ratio of vinyl aromatic hydrocarbon is (a) continuous mixture of vinyl aromatic hydrocarbon and conjugated diene. And / or (b) a polar aromatic compound or a randomizing agent is used to copolymerize the vinyl aromatic hydrocarbon and a conjugated diene to adjust the vinyl aromatic hydrocarbon content. The ratio of the weight average molecular weight to the number average molecular weight of the combined component is (c) by changing the quantitative ratio of the vinyl aromatic hydrocarbon used in A ₁ part and A ₂ part, or A ₁ part, A ₂ part and It is adjusted by changing the quantitative ratio of the vinyl aromatic hydrocarbon used in A ₃ part, and the melt flow index is adjusted by changing (d) the amount of the catalyst. The present invention relates to a method for producing a lock copolymer resin.

Hereinafter, the present invention will be described in detail.

The block copolymer in the method of the present invention has at least 2
A vinyl aromatic hydrocarbon-based polymer segment and at least one conjugated diene-based polymer segment, wherein the vinyl aromatic hydrocarbon-conjugated diene weight ratio is from 65/35 to 95. / 5, preferably 70 / 30-
It is a 90/10 block copolymer. When the content of the vinyl aromatic hydrocarbon is less than 65% by weight, rigidity and surface hardness are poor, and when it exceeds 95% by weight, impact resistance is poor, which is not preferable. In the present invention, the polymer segment mainly composed of vinyl aromatic hydrocarbon is a polymer segment having a vinyl aromatic hydrocarbon content of 50% by weight or more, and a random copolymer of a conjugated diene and a vinyl aromatic hydrocarbon. It may be composed of a polymer portion and a vinyl aromatic hydrocarbon polymer portion, or may be composed of only a vinyl aromatic hydrocarbon homopolymer portion. Further, the polymer segment mainly containing a conjugated diene is a polymer segment having a vinyl aromatic hydrocarbon content of less than 50% by weight, and a random copolymer part of a conjugated diene and a vinyl aromatic hydrocarbon and / or It is composed of conjugated diene polymer moieties. The vinyl aromatic hydrocarbon in the copolymer part may be distributed uniformly or in a taper shape.

In the present invention, the polymer segment mainly composed of vinyl aromatic hydrocarbons has a glass transition temperature (Tg) of 87 ° C.
It is preferably higher than 90 ° C., preferably 89 ° C. or higher in terms of heat resistance. A block copolymer having a Tg of more than 87 ° C. in the segment can be used at a higher temperature as compared with a block copolymer having a Tg of less than that. Tg is
It can be obtained from the inflection point of the dynamic elastic modulus measured by Vibron (manufactured by Toyo Baldwin Co., Ltd.).

The block copolymer in the method of the present invention has a ratio of the weight average molecular weight (hereinafter referred to as w) to the number average molecular weight (hereinafter referred to as n) of the vinyl aromatic hydrocarbon polymer component contained in the block copolymer. Is 1.2 to 2.0, preferably 1.3 to 1.8, and melt flow index (measured by JIS K-6870. Conditions are G conditions and temperature is 20).
0 ° C, weight 5 kg) is 2 to 50 g / 10 min. , Preferably 3 to 35 g / 10 min. Is. If the w / n ratio is less than 1.2, the impact resistance is poor, and if it exceeds 2.0, molding anisotropy occurs and the molded product warps. If the melt flow index is less than 2, the fluidity is poor and the injection moldability is poor. If it exceeds 50, the impact resistance is poor.

The w / n of the vinyl aromatic hydrocarbon polymer component can be measured as follows. A vinyl aromatic hydrocarbon polymer component 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 (L.
M. KOLTHOFF, et al., J. Polym.sci. 1, 429 (194
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 magnetic edition>" published by Kodansha). . The calibration curve for GPC is G
What was made using the standard polystyrene marketed for PC is used.

The block copolymer in the method of the present invention has excellent impact resistance and rigidity.

The block copolymer has a weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 65/35 to 85/15, preferably 70/30 to 80/20, and a block ratio of vinyl aromatic hydrocarbon of 88. More than 90% by weight, preferably 90
A block copolymer of not less than wt% or a vinyl aromatic hydrocarbon / conjugated diene weight ratio of 75/25 to 95/5,
The block copolymer preferably has a ratio of 80/20 to 90/10 and a vinyl aromatic hydrocarbon block ratio of 70 to 88% by weight, preferably 75 to 85% by weight. In particular, the latter has a feature that the surface hardness is extremely excellent.
The vinyl aromatic hydrocarbon block ratio here means the amount of the vinyl aromatic hydrocarbon polymer component obtained by decomposing the block copolymer by the above-mentioned oxidative decomposition method, It is a value (percentage) gradually divided by the amount of vinyl aromatic hydrocarbon contained in the polymer.

As described above, the block copolymer of the present invention has a polymer structure represented by the general formula (A) A ₁ -B ₁ -A ₂ (B) B ₁ -A ₁ -B ₂ -A ₂ (C) A _1-. A linear block copolymer represented by B ₁ -A ₂ -B ₂ -A ₃ , or a general formula (d) (A ₁ -B ₁ -A ₂ ) _{m + 2-} X (e) (A ₁ -B ₁ -A 2 _-B 2) radial block copolymer represented by _m + ₂ -X, (in the above formula, a is a random copolymer portion and a vinyl aromatic hydrocarbon polymer of a conjugated diene and a vinyl aromatic hydrocarbon Shows a polymer segment composed of a portion and having a vinyl aromatic hydrocarbon content of 50% by weight or more, or a polymer segment composed of only a vinyl aromatic hydrocarbon homopolymer portion, and B is a conjugated diene. Land with vinyl aromatic hydrocarbons Consists copolymer moiety and / or a conjugated diene polymer portion, .m vinyl aromatic hydrocarbon content indicates polymer segment is less than 50 wt%
Is an integer of 1 to 5. X represents a residue of the coupling agent or a residue of the initiator of the polyfunctional organolithium compound. ) Is a block copolymer represented by.

The block copolymer of the present invention is obtained by polymerizing an organolithium compound in a hydrocarbon solvent as an initiator.

Hydrocarbon solvents include butane, pentane, hexane, isopentane, heptane, octane, isooctane and other aliphatic hydrocarbons; cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane and other alicyclic hydrocarbons; or benzene, Aromatic hydrocarbons such as toluene, ethylbenzene and xylene can be used. Organolithium compounds have 1 in the molecule
An organolithium compound having at least one lithium atom bonded thereto, such as ethyllithium, n-propyllithium,
Examples thereof include isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium and isoprenyl dilithium.

In the present invention, vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene and p-te.
rt-Butylstyrene, 1,3-dimethylstyrene, α-
Methyl styrene, vinyl naphthalene, vinyl anthracene and the like are available, but styrene is particularly common. These may be used alone or in combination of two or more. The conjugated diene is diolefin having a pair of conjugated double bonds, for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl 1,3-butadiene, 1 , 3-
Examples include pentadiene and 1,3-hexadiene, and particularly common examples include 1,3-butadiene and isoprene. These may be used alone or in combination of two or more.

In producing the block copolymer of the present invention, as a method of adjusting the block ratio of vinyl aromatic hydrocarbons, (i) a mixture of vinyl aromatic hydrocarbons and conjugated dienes is continuously supplied to a polymerization system. Polymerize.

And / or (ii) a method in which a vinyl aromatic hydrocarbon and a conjugated diene are copolymerized using a polar compound or a randomizing agent can be adopted. 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 obtained by the method of the present invention has a vinyl aromatic hydrocarbon content of 60 outside the range specified in the present invention.
Block copolymer resin of vinyl aromatic hydrocarbon and conjugated diene of ~ 95% by weight, block aromatic elastomer of vinyl aromatic hydrocarbon and conjugated diene of less than 60% by weight vinyl aromatic hydrocarbon content, Polymers of the vinyl aromatic hydrocarbon-based monomers, vinyl aromatic hydrocarbon-based monomers and other vinyl monomers such as ethylene, propylene, butylene, vinyl chloride, vinylidene chloride, vinyl acetate, and methyl acrylate. Acid ester; Methacrylic acid ester such as methyl methacrylate;
At least one polymer selected from a copolymer with acrylonitrile and the like, a rubber-modified impact resistant styrene resin (HIPS) and the like can be blended to improve rigidity and impact resistance.

Various additives can be added to the block copolymer obtained by the method of the present invention depending on the purpose. Suitable additives include 30 parts by weight or less of a coumarone-indene resin, a terpene resin, a softening agent such as oil, and a plasticizer. Further, various stabilizers, pigments, antiblocking agents, antistatic agents, lubricants and the like can be added. Incidentally, as antiblocking agents, lubricants, antistatic agents, for example, fatty acid amides, ethylene bis stearamide, sorbitan monostearate, saturated fatty acid esters of aliphatic alcohols, pentaerythritol fatty acid esters, etc., and as ultraviolet absorbers, pt-Butylphenyl salicylate, 2- (2'-hydroxy-5'-methylphenyl)
Benzotriazole, 2- (2'-hydroxy-3'-
t-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,5-bis- [5'-t-butylbenzoxazolylu (2)] thiophene, etc., "Handbook for Additives for Plastics and Rubber" The compounds described in (Chemical Industry Co., Ltd.) can be used. These are generally 0.01-5
It is used in the range of weight%, preferably 0.1 to 2 weight%.

〔Example〕

 Hereinafter, the present invention will be described more specifically with reference to examples.

Examples 1 and 2 and Comparative Examples 1 to 6 A styrene / butadiene block copolymer having a polymer structure represented by the general formula A ₁ -B-A ₂ was produced in cyclohexane using n-butyllithium as a catalyst. In the production of the block copolymer, the w / n of the polystyrene component incorporated in the block copolymer is adjusted by changing the ratio of the styrene amount used for A ₁ part and the styrene amount used for A ₂ part. The block ratio of styrene was adjusted by continuously supplying a mixed monomer of styrene and butadiene as a monomer of part B to the polymerization vessel and simultaneously changing the ratio. In addition, the melt flow index (MI
(G)) was adjusted by changing the amount of n-butyllithium. The obtained block copolymer was pelletized by an extruder, and then a flat plate having a thickness of 3 mm was injection-molded at 200 ° C. using IS-80A (5oz injection molding machine) manufactured by Toshiba Machine Co., Ltd.

The physical properties of the obtained injection-molded product are shown in Table 1. The block copolymer within the range specified in the present invention was a molded product having excellent transparency, impact resistance and surface hardness, and having less warpage. The glass transition temperatures of the block copolymers of Examples 1 and 2 were both about 93 ° C.

Examples 3 to 6 A styrene / butadiene block copolymer having a polymer structure represented by the general formula A ₁ -B-A ₂ was produced by the same method as in Examples 1 and 2, and the performance of the obtained block copolymer was measured. Is shown in Table 2.

The glass transition temperatures of the block copolymers of Examples 3 to 6 were all 88 ° C or higher.

Examples 7 and 8 the polymer structure formula _B 1 _-A 1 _{-B 2 -A} 2 and _{A 1}
Styrene-butadiene block copolymer represented by -B ₁ -A ₂ -B ₂ -A ₃ was prepared in the same manner as described above. In addition, tetrahydrofuran is used as a polymerization solvent in an amount of 0.1% by weight.
The contained cyclohexane was used.

Table 3 shows the physical properties of the injection-molded products. The glass transition temperatures of the block copolymers of Examples 7 and 8 were about 90 ° C and about 93 ° C, respectively.

EXAMPLE 9 Polymer structure formula _{A 1 -A '1 -B-A} ' 2 -A 2
[A ₁ and A ₂ are polystyrene blocks,
A _'1 and _{A' 2} the weight ratio of styrene / butadiene 8
It is a 0/20 random copolymer block (each containing 10% by weight in the polymer chain), and B is a polybutadiene block.] Styrene content 81% by weight, styrene block ratio 80%, MI (G) 10g / 10mi
n, a block copolymer having a polystyrene component w / n of 1.5 incorporated in the block copolymer was produced. The glass transition temperature of the part corresponding to part A of this block copolymer is 80 ° C, and the Vicat softening point (JIS K-7
(According to 206) was about 75 ° C.

On the other hand, in the block copolymers of Examples 2 and 5, the glass transition temperature of the portion corresponding to the portion A was 93, respectively.
C. and 89 ° C., and their Vicat softening points were 90 ° C. and 83 ° C., respectively.

From these results, the block copolymer having the glass transition temperature of the portion corresponding to the portion A exceeding 87 ° C. had better heat resistance.

Example 10 A living polymer having an A ₁ -B-A ₂ structure was produced by the same method as in Example 1 except that the amount of n-butyllithium was changed, and then coupled with silica tetrachloride to obtain a general polymer structure. formula The styrene content is 82% by weight, the styrene block rate is 92%, the MI (G) is 6 g / 10 min, and the w / w ratio of the polystyrene component incorporated in the block copolymer is
A styrene / butadiene block copolymer having n of 1.7 was produced.

The block impact coefficient of the obtained block copolymer is 12 kg-c.
m, flexural modulus 18000 kg / cm ² , pencil hardness 2B, Haze
2%, the molding shrinkage of the molded product was less than 0.2%.

Example 11 Monomer _A 2 in the same manner as in Example 7 except for changing the order of addition and n- butyllithium amount of _-B 2 _-A 1 -B
_After a living polymer having _one structure is produced, it is coupled with dimethyl adipate to form a polymer having a general structure. (X residue of adipic acid dimethyl ester),
Styrene content is 75% by weight, block ratio of ethylene is 85
%, MI (G) is 10 g / 10 min, and the w / n of the polystyrene component incorporated in the block copolymer is 1.
A styrene / butadiene block copolymer of 3 was produced.

The block copolymer obtained has a dart impact value of 150 kg-c.
More than m, flexural modulus 9000kg / cm ² , pencil hardness 6B, H
The aze was 3% and the molding shrinkage was less than 0.2%.

[Effect]

The block copolymer obtained by the method of the present invention is transparent and has excellent impact resistance and surface hardness, and therefore can be suitably used as a material for injection molding. In particular, since the block copolymer obtained by the method of the present invention has little warpage when injection-molded, it is suitable for flat plate-shaped products, molded products having many flat plate-shaped portions, and large-sized molded products. The injection-molded article of the block copolymer obtained by the method of the present invention is used for various applications in which an injection-molded article of a general-purpose thermoplastic resin is used, such as in the fields of toys, daily necessities, food containers, miscellaneous goods, and light electric parts. Can be used. Incidentally, the block copolymer obtained by the method of the present invention is a sheet, an extrusion molded product such as a film, and a molded product thermoformed by vacuum, compressed air, etc., if necessary, specifically food container packaging, blister. It can also be used in a wide range of container packaging materials such as packaging materials, packaging films for fruits and vegetables and confectionery.

Claims (1)

[Claims] 1. A polymer structure having a general formula (A) A ₁ -B ₁ -A ₂ (B) B ₁ -A ₁ -B ₂ -A ₂ (C) A ₁ -B ₁ -A ₂ -B ₂ linear block copolymer represented by -A _3, or the general formula _{(d) (A 1 -B 1 -A 2} ) m + 2 -X ( _{e) (A 1 -B 1 -A 2} -B 2) m + 2 A radial block copolymer represented by -X, (wherein A is composed of a random copolymer part of a conjugated diene and a vinyl aromatic hydrocarbon and a vinyl aromatic hydrocarbon polymer part, a vinyl aromatic A polymer segment having a hydrocarbon content of 50% by weight or more or a polymer segment composed only of a vinyl aromatic hydrocarbon homopolymer portion is shown, and B is a random mixture of a conjugated diene and a vinyl aromatic hydrocarbon. Copolymer moiety and / or conjugated diester Consists down polymer portion, .m vinyl aromatic hydrocarbon content indicates polymer segment is less than 50 wt%
Is an integer of 1 to 5. X represents a residue of the coupling agent or a residue of the initiator of the polyfunctional organolithium compound. (I) The weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 65/35 to 85/15, and the block ratio of vinyl aromatic hydrocarbon is 88% by weight. Or a vinyl aromatic hydrocarbon to conjugated diene weight ratio of 75 /
25 to 95/5, the block ratio of vinyl aromatic hydrocarbon is 70 to 80% by weight, and (ii) the ratio of the weight average molecular weight to the number average molecular weight of the vinyl aromatic hydrocarbon polymer component is 1.2. To 2.0, and (iii) melt flow index (measured by JIS K-6870. Conditions are G condition, temperature 200 ° C., load 5 kg) is 2 to 50 g / 10 min. When the block copolymer resin is a hydrocarbon solvent using an organolithium compound as an initiator, the block ratio of vinyl aromatic hydrocarbon is (a) continuous mixture of vinyl aromatic hydrocarbon and conjugated diene. And / or (b) a polar aromatic compound or a randomizing agent is used to copolymerize the vinyl aromatic hydrocarbon and a conjugated diene to adjust the vinyl aromatic hydrocarbon content. The ratio of the weight average molecular weight to the number average molecular weight of the combined component is (c) by changing the quantitative ratio of the vinyl aromatic hydrocarbon used in A ₁ part and A ₂ part, or A ₁ part, A ₂ part and It is adjusted by changing the quantitative ratio of the vinyl aromatic hydrocarbon used in A ₃ part, and the melt flow index is adjusted by changing (d) the amount of the catalyst. Method for producing lock copolymer resin.