JPS61254650A - Block copolymer composition and production thereof - Google Patents

Abstract

PURPOSE:The organic lithium compound is added in two portions to effect polymerization whereby the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is adjusted to give the title composition which is used suitably to make food-packaging vessels, because it is clear and high in surface hardness and impact strength. CONSTITUTION:After a living polymer of a vinyl aromatic hydrocarbon and a conjugated diene at a weight ration of more than 60/40 is formed by polymerization of M1pts.wt. of monomers using C1 moles of the organic lithium compound, M2pts.wt. of monomers at less than 80/20 ratio of the vinyl aromatic hydrocarbon to the conjugated diene are polymerized with C2 moles of the organic lithium compound and further, M3pts.wt. of monomers at more than 60/40 ratio are polymerized where the amounts of the organic lithium compound and monomers satisfy equations I and II where M1+M2+M3=100pts.wt. These operations give a block copolymer composition at 60/40-95/5 ratio of the vinyl aromatic hydrocarbon to the conjugated diene.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a block copolymer that is transparent and has excellent mechanical properties, particularly surface hardness and impact resistance, and is particularly suitable for injection molding, and a method for producing the same. It is.

[Conventional technology]

When a block copolymer consisting of a conjugated diene and a vinyl aromatic hydrocarbon has a relatively high vinyl aromatic hydrocarbon content, a thermoplastic resin with excellent transparency and better impact resistance than polystyrene can be obtained. Its usage has been increasing in recent years, mainly in fields such as food packaging containers, daily necessities, toys, and light electrical parts.

Methods for producing such block copolymers are disclosed in Japanese Patent Publications No. 36-19286, Japanese Patent Publication No. 17979-1979, Japanese Patent Publication No. 2423-1982, and Japanese Patent Publication No. 57-49.
567, Japanese Patent Publication No. 5B-11446, and the like.・[Problems to be solved by the invention] However, the block copolymers specifically disclosed in these methods do not have sufficient impact resistance, especially the dart impact resistance of injection molded products, and improvement thereof is desired. It is rare. Deterioration in dart impact resistance is a major problem, especially in large molded products, as there is a risk of cracking and cracking. Furthermore, in injection molding, materials with high surface hardness and resistance to scratches are nitrided, but conventional block copolymer resins have a problem in that impact resistance decreases when surface hardness is improved.

Under such current circumstances, the present inventors have conducted studies on obtaining molded products with excellent impact resistance and surface hardness, and have found that in the manufacture of block copolymers, segments with high styrene content are added to the terminals of block copolymers. They discovered that the objective could be achieved by adding the organolithium compound in two portions within a specific range and adjusting the content of vinyl aromatic hydrocarbons, leading to the completion of the present invention. Ta.

[Means for solving problems]

(a) The polymer structure has the general formula % (where A and A are polymer segments in which the weight ratio of vinyl aromatic hydrocarbon to conjugated diene exceeds 60/40, and B is A polymer segment in which the weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 80/20 or less.
The weight ratio of vinyl aromatic hydrocarbon and conjugated diene is 60/
A composition comprising 60 to 5 parts by weight of a polymer exceeding 40, wherein 5% or more and less than 35% of the polymer base of (a) has substantially the same structure as the polymer base of (a), and The present invention relates to a block copolymer composition having an overall weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 60/40 to 9515, and a method for producing the same.

In the composition of the present invention, the weight ratio of vinyl aromatic hydrocarbon to conjugated diene in segments A and A2 of the block copolymer (a) exceeds 60/40, preferably 8
It is 0/20 or more. When the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene in the segment is 60/40 or less, the surface hardness is poor. Further, the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene in segment B of the block copolymer (a) is 80/20 or less, preferably 65/35 or less. In particular, to obtain a good surface hardness, 65/
35 to 10/90 is recommended. If the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene in the segment exceeds 80/20, the dart impact strength will be poor, which is not preferable.

Next, the weight ratio of vinyl aromatic hydrocarbon to conjugated diene is more than 60/40, preferably 80/2.
It is 0 or more. When the weight ratio of vinyl aromatic hydrocarbon to conjugated diene in the polymer is 60/40 or less, the surface hardness is poor.

The composition of the present invention includes a block copolymer (a). Here, having substantially the same structure means that the structure that determines the polymer, such as molecular weight, distribution, composition (ratio of vinyl aromatic hydrocarbon to conjugated diene), etc., is within the control range of manufacturing conditions and within the range of analytical error. Indicates that they are the same. When the proportion of polymer chains having substantially the same structure as that of polymer (b) is 35% or more, the surface hardness decreases;
If it is less than 20%, the transparency will decrease, which is not preferable.

In the composition of the present invention, the weight ratio of block copolymer (a) to polymer (b) is 40/60 to 9515, preferably 50150 to 90/10. If the weight ratio is outside this range, impact resistance will be poor. Furthermore, the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene in the entire composition of the present invention is 6.
0/40-9515, preferably 70/30-90/1
It is 0. If this weight ratio is less than 60/40, the rigidity
Surface hardness is poor, and if it exceeds 9515, impact resistance decreases, which is not preferable.

In the composition of the present invention, segment A9 in the block copolymer (a), segment Aa in the polymer) is a vinyl aromatic hydrocarbon polymer, which makes the block copolymer excellent in rigidity and surface hardness. preferred in terms of obtaining

Further, it is recommended that the vinyl aromatic hydrocarbon content in the A and -B portions of the block copolymer (a) exceeds 60% by weight in order to obtain a block copolymer with good surface hardness.

In the present invention, when the block copolymer (a) and/or the polymer (b) has a random copolymer portion of a vinyl aromatic hydrocarbon and a conjugated diene, the vinyl aromatic hydrocarbon is uniformly distributed. It may also be distributed in a tapered shape.

The number average molecular weight of the block copolymer (a) of the present invention is s
o,ooo~500,000, preferably 80.00
0 to 300.000.

When the composition of the present invention is used for injection molding, the melt flow index (JIS -6870, 200°C
It is preferable to control the weight so that the load (5 kg) is in the range of 1 to 40 g/10 m1n.

In the present invention, a preferable block copolymer composition in terms of mechanical properties such as rigidity, surface hardness, and impact resistance has a vinyl aromatic hydrocarbon block rate of 40 to 95% by weight in the block copolymer (a). belongs to. Here, the block rate of vinyl aromatic hydrocarbon 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. et al., Journal of Polymer Science (L,M,
KOL↑■OFF, et al, +J, Po1ya+,
429 (1946)] and divided by the amount of vinyl aromatic hydrocarbon contained in the block copolymer.

The block copolymer composition of the present invention can be obtained by polymerization in a hydrocarbon solvent using an organolithium compound as an initiator. As long as the composition of the present invention satisfies the requirements defined by the present invention, the production method thereof is not particularly limited, but preferred methods include the following method.

That is, in the first step, M2 parts by weight of monomers are polymerized using C3 moles of an organolithium compound to form a polymer in which the weight ratio of vinyl aromatic hydrocarbon to conjugated diene exceeds 60/40, preferably 80/20 or more. forming a polyurethane polymer, and then in a second step, the weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 80/20 or less, preferably 6
M for monomers of 5/35 or less.

Part by weight is added and polymerized, and then in the third step the weight ratio of vinyl aromatic hydrocarbon and conjugated diene is 60/40.
When performing polymerization by adding a seven-mer MJ amount exceeding 80/20, preferably 80/20 or more, in the third step, 0.2 mol of an organolithium compound is newly added, and the amount of the organolithium compound used is This method is performed within the range where the relationship satisfies the following conditions [1] and [2].

(However, M, + M2 + M3 = too parts by weight.) Condition (2) is in the polymer)/weight of block copolymer (a).

Corresponding to the ratio, condition (2) indicates the proportion of polymer chains having substantially the same structure as the polymer [b) in the polymer chains of the block copolymer (a). In addition, in the above method, the organic lithium compound newly added in the third step is
Although it is preferable to add the entire amount at the beginning of the process, it may be added in the middle of the third process or in portions if necessary.

In the present invention, the hydrocarbon solvent is preferably an alicyclic hydrocarbon such as cyclopenkune, methylcyclopenkune, cyclohexane, methylcyclohexane, or ethylcyclohexane; or an aromatic hydrocarbon such as benzene, toluene, ethylbenzene, or xylene; , pentane, hexane, isopentane, heptane, octane, isooctane, and other aliphatic hydrocarbon-based solvents are not preferred because the polymer formed in the first step is difficult to dissolve uniformly.

Preferred organolithium compounds for the present invention are organolithium compounds in which one or more lithium atoms are bonded in the molecule, such as ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, 5ec.
-butyllithium, tert-butyllithium, hexamethylene dilithium, butaneyl dilithium, isoprenyl dilithium, and the like.

In the present invention, examples of vinyl aromatic carbonization and hydrogen include styrene, 0-methylstyrene, p-methylstyrene, p-
Examples include tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and styrene is particularly common. These may be used not only alone, but also as a mixture of two or more.

The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene. , 1.3-pentagene,
Examples include 1,3-hexadiene, and particularly common examples include 1,3-butadiene and isoprene.

These may be used not only alone, but also as a mixture of two or more.

When producing the block copolymer composition of the present invention, the method for adjusting the block rate of vinyl aromatic hydrocarbon is as follows: (i) A mixture of vinyl aromatic hydrocarbon and conjugated diene is continuously added to the polymerization system. Methods such as (ii) copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene using a polar compound or a randomizing agent can be employed. As polar compounds and randomizing agents,
Ethers such as tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylene diamine, thioethers, phosphines,
Examples include phosphoramides, alkylbenzene sulfonates, potassium and sodium alkoxides, and the like.

The block copolymer composition of the present invention includes a block copolymer resin of a vinyl aromatic hydrocarbon and a conjugated diene having a vinyl aromatic hydrocarbon content of 60 to 95% by weight outside the range specified in the present invention; A block copolymer elastomer of a vinyl aromatic hydrocarbon and a conjugated diene having a vinyl aromatic hydrocarbon content of 60% by weight, the above vinyl aromatic hydrocarbon-based polymer, the above vinyl aromatic hydrocarbon Hydrocarbon-based polymers and other vinyl monomers, such as ethylene, propylene, butylene, vinyl chloride, vinylidene chloride, vinyl acetate, acrylic esters such as methyl acrylate; methacrylic esters such as methyl methacrylate; acrylonitrile, etc. Rigidity, impact resistance, etc. can be improved by blending at least one polymer selected from copolymers, rubber-modified impact styrenic resins (HIPS), and the like.

Various additives can be added to the block copolymer composition of the present invention depending on the purpose. Suitable additives include 30 parts by weight or less of coumaron-indene resins, terpene resins, softeners such as oils, and plasticizers. In addition, various stabilizers, pigments, antiblocking agents, antistatic agents,
A lubricant etc. can also be added. In addition, examples of antiblocking agents, lubricants, and antistatic agents include fatty acid amide, ethylene bissteramide, sorbitan monostearate, saturated fatty acid esters of aliphatic alcohols, and pentaerythritol fatty acid esters, and as ultraviolet absorbers, p
-t-butylphenyl salicylate, 2-(2°-hydroxy-5'-methylphenyl)benzotriazole,
2- (2'-hydroxy-3'-t-butyl-5'-
methylphenyl)-5-chlorobenzotriazole, 2
,5-bis-(5'-t-butylbenzoxazolyl(
2) Compounds such as thiophene described in "Practical Handbook of Additives for Plastics and Rubber" (Kagaku Kogyo Co., Ltd.) can be used. These are generally used in an amount of 0.01 to 5% by weight, preferably 0.1 to 2% by weight.

〔Effect of the invention〕

The block copolymer composition of the present invention is transparent and has excellent impact resistance and surface hardness, and can be used as a molding material for various molded products. The block copolymer composition of the present invention can be molded as it is or after being colored by the same processing means as ordinary thermoplastic resins. In particular, the block copolymer composition of the present invention can be suitably used as a material for injection molding, and ordinary general-purpose thermoplastic resins can be used in the fields of toys, daily necessities, food packaging containers, miscellaneous goods, office equipment parts, light electrical parts, etc. Can be used for various purposes. In addition, the block copolymer composition of the present invention can be used in extrusion molded products such as sheets and films, molded products thermoformed by methods such as vacuum forming and pressure forming, or molded products formed by blow molding, food packaging containers, etc. It can be widely used in fields such as blister packaging materials, packaging films for fruits and vegetables, and confectionery.

〔Example〕

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 Cyclohexane 57! was purified and dried after purifying the interior of the autoclave with nitrogen gas. 200 g of purified and dried styrene was charged as a monomer.

Next, 4.1 mmol of n-butyllithium was added as a C2 catalyst. The autoclave was heated to 70° C. and stirring was continued for 90 minutes. Next, 200g of M2 mono-7-C utilene
A mixture of 150 g of purified and dried butadiene was prepared, and this mixture was added at a constant rate over 60 minutes using a plunger pump, and polymerization was continued at 70°C. Next, after adding 5.3 mmol of n-butyllithium as a 02 catalyst, M
9. Add 450 g of styrene as a monomer and heat at 70°C.
After continuing polymerization for 0 minutes, 2 ml of methanol was added to stop the polymerization, and 10 g of 4-methyl-2,
6-tert-butylphenol was added.

The obtained block copolymer composition was pelletized using an extruder, and then injection molded into a flat plate with a thickness of 3 mm at 200° C. using an injection molding machine. The molded product was transparent, shiny, and had good hardness. Table 1 shows the physical properties of the injection molded product obtained.

(Margin below) Notes to Table 1: 1) Indicates the proportion of the portion having substantially the same structure as the polymer chain of polymer (b) in the polymer chain of block copolymer (a).

2) Compliant with ASTM D-1709 3) AS
TM D-790 quasi-1 4) JIS K-540
JIS K-6714, semi-I processing Examples 2 to 4 and comparative examples 1 to 7 Using the same equipment as in Example 1, changing the composition of M2, M2, and M3 monomers and changing the polymer ( b)/block copolymer (a)
Polymerization was carried out in substantially the same manner as in Example 1, except that 01 and C2 (mmol) were changed in order to adjust the weight ratio of and the proportion of polymer chains having the same structure to predetermined values.

Table 2 shows the physical properties of the composition measured by the same method as in Example 1. It is clear that block copolymer compositions within the scope of the present invention have excellent transparency, impact resistance and surface hardness.

Examples 5 to 7 Using the same apparatus as in Example 1, tetrahydrofuran was added to 1.5 ml of cyclohexane in advance to carry out polymerization. For polymerization of M7, Ml, and M3 monomers, the polymerization temperature is approximately 60°C.
Polymerization was carried out for 60 minutes while adjusting the temperature so that the temperature was 0.degree. C2, the amount of negative catalyst is a
The weight ratio of 1 and the proportion of polymer chains having the same structure were added so that the values shown in Table 3 were obtained.

The block copolymer composition was molded and measured in the same manner as in Example 1. Various physical properties are displayed in the third display.

Table 3 Comparative Example 8 Instead of the polystyrene contained in the block copolymer composition of Example 2, polystyrene (manufactured by radical polymerization) having a weight average molecular weight of about 250,000 was used, and the block copolymer (a ) was obtained which did not have the same structure in the polymer chain as the polystyrene used. The resulting composition has Ha
The ze was 12% and the transparency was poor.

Example 8 Using the same equipment as in Example 1, monomers were charged with the following composition.

Styrene was added and polymerized. In addition, C5, C2, (mmol) in the polymer)/weight be of block copolymer (a) is 10/90, and the proportion of polymer groups with the same structure is 2.
Polymerization was carried out in the same manner as in Example 1 except that the concentration was changed to 2%. The physical properties of the polymer measured by the same method as in Example 1 showed that the dart impact value was 15 kg-c.
m, flexural modulus was 17000 Kg/cd, pencil hardness was B, and Haze value was 3%.

Claims (2)

[Claims] (1) (a) The polymer structure has the general formula A_1-B-A_2 (where A_1 and A_2 are polymer segments in which the weight ratio of vinyl aromatic hydrocarbon and conjugated diene exceeds 60/40, and B is a vinyl A polymer segment in which the weight ratio of aromatic hydrocarbon to conjugated diene is 80/20 or less.) 40 to 95 parts by weight of a block copolymer represented by (b)
The weight ratio of vinyl aromatic hydrocarbon and conjugated diene is 60/
A composition comprising 60 to 5 parts by weight of a polymer exceeding 40, wherein 5% or more and less than 35% of the polymer chains of (a) contain (
A block copolymer composition having substantially the same structure as the polymer chain of b), and having a weight ratio of vinyl aromatic hydrocarbon to conjugated diene in the composition as a whole from 60/40 to 95/5. (2) in the first step, polymerize M_1 parts by weight of monomer using C_1 mol of organolithium compound to form a limping polymer with a weight ratio of vinyl aromatic hydrocarbon to conjugated diene exceeding 60/40; Thereafter, in the second step, M_2 parts by weight of a monomer having a weight ratio of vinyl aromatic hydrocarbon and conjugated diene of 80/20 or less is added and polymerized, and then in the third step, the vinyl aromatic hydrocarbon and conjugated diene are combined. Monomer M with a weight ratio exceeding 60/40
When performing polymerization by adding _3 parts by weight, C_2 moles of the organolithium compound are newly added in the third step, and the relationship between the organolithium compound used and the amount of monomer satisfies the following conditions [1] and [2]. The weight ratio of the vinyl aromatic hydrocarbon and the conjugated diene is 60/4.
A method for producing a block copolymer composition having a ratio of 0 to 95/5. [1] 60/40≦C_2/{C_1+[(M_1+M
_2)/M_3](C_1+C_2)}≦5/95[2
]5≦C_1/{C_1+[(M_1+M_2)/M_
3] (C_1+C_2)}×100<35 (However, M_1
+M_2+M_3=100 parts by weight. )