JPH0249015A - Production of block copolymer resin - Google Patents

Abstract

PURPOSE:To provide the subject resin having a specific structure and a melt index and giving scarcely warped moldings having high transparency, impact resistance and hardness by continuously charging an aromatic vinyl compound and a conjugated diene in a polymerization system and subsequently copolymerizing the monomers in the presence of an organic Li compound in a solvent. CONSTITUTION:A mixture of an aromatic vinyl hydrocarbon and a conjugated diene is continuously charge in a polymerization system and subsequently copolymerized in the presence of an organic Li compound as an initiator in a hydrocarbon solvent, if necessary, in the presence of a polar compound or randomizing agent to provide a resin comprising a linear block copolymer of formula I-III (A is a segment comprising an aromatic vinyl hydrocarbon polymer portion and a random copolymer portion of the conjugated diene with >=50wt.% of the aromatic vinyl hydrocarbon; B is a segment comprising a conjugated diene-aromatic vinyl hydrocarbon random copolymer portion and/or a conjugated diene portion and having a conjugated diene content of >=50wt.%; n is 1-5) or a radial block copolymer of formula IV-VII (X is coupling agent residue; m is 1-5), the resin having a weitht-average mol. wt./number-average mol. wt. ratio of 1.2-2.0 and a melt index of 2-50g/10min.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a block copolymer resin for injection molding, which provides a molded article with excellent transparency, impact resistance, and surface hardness, and with little warpage.

[Conventional technology]

A block copolymer consisting of a conjugated diene and a vinyl aromatic hydrocarbon has excellent transparency when the vinyl aromatic hydrocarbon content is relatively high, and a thermoplastic resin with 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. 4B-2423, and Japanese Patent Publication No. 57-49.
567, Japanese Patent Publication No. 5B-11446, and the like.

[Problem to be solved by the invention]

However, the block copolymers specifically disclosed in these methods do not have sufficient impact resistance, particularly dart impact resistance of injection molded products, and improvement thereof is desired. In addition, since injection molding is performed under high shear, the molded product tends to have anisotropy, which can cause the strength to weaken in a certain direction.
This tends to cause problems such as warping of molded products. Especially when molding large molded products or flat plates, warping is likely to occur, so there is a demand for materials with less warping. Furthermore, in injection molding, materials with good surface hardness and resistance to scratches are desired, but conventional block copolymer resins have a problem in that impact resistance decreases when surface hardness is improved.

Under these circumstances, the inventors of the present invention have conducted studies to obtain molded products with excellent impact resistance and surface hardness, and with little warpage. They discovered that the objective could be achieved by setting the molecular weight distribution of the components within a certain range and adjusting the content of vinyl aromatic hydrocarbons and the block rate of vinyl aromatic hydrocarbons, thereby completing the present invention. It was.

[Means to solve the problem]

That is, the present invention provides a linear block copolymer whose polymer structure is represented by the formula %) or a radial block copolymer represented by the formula % (in the above formula, A is a conjugated diene). A polymer segment or vinyl aromatic hydrocarbon that is composed of a random copolymer part of and a vinyl aromatic hydrocarbon and a vinyl aromatic hydrocarbon polymer part, and the content of vinyl aromatic hydrocarbon is 50% by weight or more. r indicates a polymer segment consisting only of a homopolymer portion; B is a polymer segment consisting of a random copolymer portion of a conjugated diene and a vinyl aromatic hydrocarbon and/or a conjugated diene polymer portion; Indicates a polymer segment having a content of less than 50% by weight.

n is an integer from 1 to 5. X represents a residue of a coupling agent or a residue of an initiator of a polyfunctional organolithium compound.

) In the block copolymer represented by any of (i) the weight ratio of vinyl aromatic hydrocarbon to conjugated diene is 65/35 to 85/15, and the block rate of vinyl aromatic hydrocarbon is 88% by weight or the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is 75/
25 to 9515, and the block rate of vinyl aromatic hydrocarbon is 70 to 88% by weight; (ii) the block copolymer was oxidatively decomposed with di-tert-butyl hydroperoxide using osmium tetroxide as a catalyst; Then, the ratio of the weight average molecular weight to the number average molecular weight of the vinyl aromatic hydrocarbon polymer component obtained by adding methanol to the decomposition product is 1.2 to 2.0, and (iii
) Melt flow index (JIS K-6870
Measured by. Conditions are G conditions, temperature 200°C, 1 weight 5k.
g) is 2-50 g/10mfn.

When producing a block copolymer resin in a hydrocarbon solvent using an organolithium compound as an initiator, the block rate of the vinyl aromatic hydrocarbon is changed to (a) a mixture of a vinyl aromatic hydrocarbon and a conjugated diene continuously. and/or (b) prepared by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene using a polar compound or a randomizing agent. The present invention relates to a method for producing a polymer resin.

The present invention will be explained in detail below.

The block copolymer in the method of the invention comprises at least two
Polymer segments mainly composed of vinyl aromatic hydrocarbons and a small number of polymer segments mainly composed of conjugated dienes, with a weight ratio of vinyl aromatic hydrocarbons and conjugated dienes of 65/35. ~9515, preferably 70/30~
It is a 90/10 block copolymer. If the vinyl aromatic hydrocarbon content is less than 65% by weight, the rigidity and surface hardness will be poor, and if it exceeds 95% by weight, the impact resistance will be poor, which is not preferable. In the present invention, a polymer segment mainly composed of vinyl aromatic hydrocarbons is a polymer segment with a vinyl aromatic hydrocarbon content of 50% by weight or more, and is a polymer segment consisting of a random conjugate of a conjugated diene and a vinyl aromatic hydrocarbon. It is composed of a polymer part and a vinyl aromatic hydrocarbon polymer part, or it is composed only of a vinyl aromatic hydrocarbon homopolymer part. Furthermore, a polymer segment mainly composed of a conjugated diene is a polymer segment having a vinyl aromatic hydrocarbon content of less than 50% by weight, and a random copolymer portion of a conjugated diene and a vinyl aromatic hydrocarbon and/or a polymer segment containing a vinyl aromatic hydrocarbon. Or composed of a conjugated diene polymer moiety.

The vinyl aromatic hydrocarbons in the copolymer portion may be uniformly distributed or tapered.

In the present invention, the polymer segment mainly composed of vinyl aromatic hydrocarbons has a glass transition temperature (Tg) of 87°.
C or higher, preferably 89 C or higher, from the viewpoint of heat resistance. A block copolymer in which the Tg of the segment exceeds 87°C can be used at higher temperatures than a block copolymer having a lower Tg. T
g can be determined from the inflection point of the dynamic elastic modulus measured with Pyblon (manufactured by Toyo Baldwin).

The block copolymer used in the method of the present invention has a weight average molecular weight (hereinafter referred to as "W") and a number average molecular weight (hereinafter referred to as "W") of the vinyl aromatic hydrocarbon polymer component contained in the block copolymer.
The ratio of Mn (hereinafter referred to as Mn) is 1.2 to 2.0, preferably 1.
．． The melt flow index (J
Measured according to IS K-6870.

Conditions are G condition, temperature 200'C1 weight 5kg) 2 ~
50 g/10ml, preferably 3-35g/1
0m1n. If the M w /HnO ratio is less than 1.2, the impact resistance will be poor, and if it exceeds 2.0, molding anisotropy will occur, causing the problem that the molded product will warp. Furthermore, if the melt flow index is less than 2, the injection moldability is poor due to poor fluidity, and if it exceeds 50, the impact resistance is poor.

Mw/Mn of vinyl aromatic hydrocarbon polymer component
can be measured as follows. Vinyl aromatic hydrocarbon polymer components (L, M, KOLTtlOFF , etal,,
J, Polym, sci, 1.429 (19
46) by gel permeation chromatography (GPC) and calculated according to a conventional method (for example, the method described in "Gel Chromatography Book Edition" published by Kodansha). . A calibration curve for GPC is prepared using standard polystyrene commercially available for GPC.

The Pro-Nc copolymer used 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
% by weight or more of a block copolymer, or a weight ratio of vinyl aromatic hydrocarbon and conjugated diene of 75/25 to 9515,
It is preferably a block copolymer with a ratio of 80/20 to 90/10 and a block ratio of vinyl aromatic hydrocarbon of 70 to 88% by weight, preferably 75 to 85% by weight.

In particular, the latter is characterized by extremely high surface hardness. In addition, here, the block rate of vinyl aromatic hydrocarbon is
The amount of the vinyl aromatic hydrocarbon polymer component obtained by decomposing the block copolymer using the above-mentioned oxidative decomposition method is quantified, and the amount is expressed as the amount of vinyl aromatic hydrocarbon contained in the block copolymer. It refers to the value (percentage).

As mentioned above, the block copolymer of the present invention has a polymer structure of the general formula % (% formula %) (In the above formula, A is a polymer segment mainly composed of vinyl aromatic hydrocarbons, and B is a polymer segment mainly composed of conjugated diene. The boundary between the A block and the B block does not necessarily need to be clearly distinguished. n is 1 to 5.
is an integer. ), or the linear block copolymer represented by the formula % (in the above formula, A and B are the same as above, and X is, for example, silicon tetrachloride, tin tetrachloride, epoxidized soybean oil, carboxyl It represents a residue of a coupling agent such as an acid ester or a residue of an initiator of a polyfunctional organolithium compound (m and n are integers of 1 to 5).

The block copolymer of the present invention can be obtained by polymerization in a hydrocarbon solvent using an organolithium compound as an initiator.

Hydrocarbon solvents include aliphatic hydrocarbons such as butane, pentane, hexane, isobencune, heptane, octane, and isooctane; alicyclic hydrocarbons such as cyclopentane, methylcyclopenkune, cyclohexane, methylcyclohexane, and ethylcyclohexane; or benzene. , aromatic hydrocarbons such as toluene, ethylbenzene, and xylene. Organolithium compounds have 1 in the molecule.
It is an organic lithium compound in which more than one lithium atom is combined, such as ethyllithium, n-propyllithium,
Isopropyllithium, n-butyllithium, 5ec-
Examples include butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium, isoprenyl dilithium, and the like.

In the present invention, vinyl aromatic hydrocarbons include styrene, 0-methylstyrene, p-methylstyrene, p-t
ert-butylstyrene, 1,3-dimethylstyrene,
Examples include 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, for example, 1,3
Butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1.3
-pentadiene, 1,3-hexadiene, etc.
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 of the present invention, the method for adjusting the block ratio of vinyl aromatic hydrocarbons is as follows: (i) Continuously feeding a mixture of vinyl aromatic hydrocarbon and conjugated diene to the polymerization system. and polymerize.

and/or (ii> A method of copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene using a polar compound or a randomizing agent can be adopted. As the polar compound or randomizing agent, tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc. Examples include ethers such as butyl ether, amines such as triethylamine and tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, potassium and sodium alkoxides, and the like.

The block copolymer obtained by the method of the present invention contains 60% of a vinyl aromatic hydrocarbon group outside the range specified in the present invention.
A block copolymer resin of ~95% by weight of a vinyl aromatic hydrocarbon and a conjugated diene, a block copolymer elastomer of a vinyl aromatic hydrocarbon and a conjugated diene with a vinyl aromatic hydrocarbon content of less than 60% by weight, Polymers of the above-mentioned vinyl aromatic hydrocarbon monomers, the above-mentioned vinyl aromatic hydrocarbon monomers and other vinyl monomers, such as acrylics such as ethylene, propylene, butylene, vinyl chloride, vinylidene chloride, vinyl acetate, and methyl acrylate. Acid esters; methacrylic esters such as methyl methacrylate; copolymers with acrylonitrile, rubber-modified high-impact styrenic resins (HIPS), etc. are blended to provide rigidity and impact resistance. etc. can be improved.

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 coumaron-indene resins, terpene resins, softeners such as oils, and plasticizers. Further, various stabilizers, pigments, antiblocking agents, antistatic agents, lubricants, etc. can also be added. In addition, examples of antiblocking agents, lubricants, and antistatic agents include fatty acid amide, ethylene bisstearamide, sorbitan monostearate, saturated fatty acid esters of fatty alcohols,
pentaerythol fatty acid ester, etc., and as ultraviolet absorbers, pt-butylphenyl salicylate, 2-
(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-L-
Butyl-5'methylphenyl)-5-chlorobenzotriazole, 2,5-bis-(5'-t-butylbenzolyl-(2))thiophene, etc., "Practical Handbook of Additives for Plastics and Rubber J (Chemical Industry) Compounds described in J.D. Co., Ltd. can be used.These are generally used in a range of 0.01 to 5% by weight, preferably 0.1 to 2% by weight.

(Example〕 EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1.2 and Comparative Examples 1 to 6 A styrene-butadiene block copolymer having a polymer structure represented by the general formula 2A+BAZ was produced in cyclohexane using n-butyllithium as a catalyst. In the production of the block copolymer, the amount of polystyrene component incorporated into the block copolymer is adjusted by changing the ratio of the amount of styrene used in part A1 and the amount of styrene used in part A2, The block rate of styrene was adjusted by continuously supplying a mixed monomer of styrene and butadiene as the monomer of part B to the polymerization vessel, and at the same time changing the ratio.Also, the melt flow index (M
i (G)) was adjusted by changing the amount of n-butyllithium. The obtained block copolymer was pelletized using an extruder, and then injection molded into a flat plate with a thickness of 3 mm at 200° C. using a 15-808 (5 oz injection molding machine) manufactured by Toshiba Machine Corporation.

Table 1 shows the physical properties of the injection molded product obtained. The block copolymers within the range specified by the present invention had excellent transparency, impact resistance, and surface hardness, and produced molded products with little warpage. Note that the glass transition temperature of the block copolymers of Examples 1 and 2 was approximately 93°C.

(The following is a blank space) The Mw/Mn of the polystyrene component incorporated into the block copolymer is shown.

(Note 1) Based on ASTM D-1709 (Note 2) AS
Based on TM D-790 (Note 3) JIS K-54
00 (Note 4) Based on JIS K-6714 (Note 5) The warpage of injection molded products is closely related to the difference in molding shrinkage between the flow direction of the molded product and the direction perpendicular to it, and the difference is large. The judgment was made based on the difference in molding shrinkage rate since the warpage of the injection molded product was greater.

Run as follows depending on the difference in molding shrinkage rate. It was divided into groups.

0.2% or less ◎ More than 0.2% 0.4% or less 0 More than 0.4% and less than 0.6% 8 〇、More than 6% × In addition, molding shrinkage in the direction perpendicular to the flow direction The molding shrinkage rate on the side opposite to the gate side was measured.

Examples 3 to 6 A styrene-butadiene block copolymer having a polymer structure represented by the general formula A+B Am was produced by the same method as in Example 1.2, and the performance of the obtained block copolymer was evaluated as follows. Shown in the table.

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

(The following is a blank space) *Indicates Mw/Mn of the polystyrene component incorporated into the block copolymer.

111 w/Mn of the polystyrene component incorporated into the block copolymer is shown.

Examples 7 and 8 Styrene-butadiene block copolymers having the general formulas B+ At BZ At and A, B+ Az Bz An were produced in the same manner as described above. Note that cyclohexane containing 0.1 wt% of tetrahydrofuran was used as the polymerization solvent.

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

(Left below) Example 9 Polymer structure has general formulas A, -A', -B -A part 2A2
[A and At are polystyrene blocks,
A part + and A part 2 are random copolymer blocks with a styrene/butadiene weight ratio of 80/20 (each contained in the polymer chain at 10% by weight), and B is a polybutadiene block] Styrene-containing Amount: 81% by weight, styrene block rate: 80%, M I (G): 10 g
/10m1n, and a block copolymer was produced in which the Mw/Mn of the polystyrene component incorporated into the block copolymer was 1.5. The glass transition temperature of the part corresponding to Part A of this block copolymer is 80°C, and the Vicat softening point (according to JIS K-7206) is approximately 75°.
It was C.

On the other hand, in the block copolymers of Example 2 and Example 5, the glass transition temperature of the part corresponding to part A was 93°.
C189°C, and their Vicat softening points were 90°C and 183°C, respectively.

From these results, the block copolymer in which the glass transition temperature of the portion corresponding to part A exceeds 87°C had better heat resistance.

Example 10 A living polymer having the structure A, -B-A was produced in the same manner as in Example 1 except for changing the amount of n-butyllithium, and then coupled with silica tetrachloride to make the polymer structure general. It is represented by the formula (A, -B-A2→4 Si, the styrene content is 82% by weight, the block rate of styrene is 92%, the M I (G) is 6 g/10m1n, and it is incorporated into the block copolymer. M of polystyrene component
A styrene-butadiene block copolymer with w/M n of 1.7 was produced.

The dart impact value of the obtained block copolymer was 12 kg-
cm, flexural modulus of elasticity 18000 kg/c+iN, pencil hardness 2B, Haze 2%, and molding shrinkage of the molded product was less than 0.2%.

Example 11 A2B2 At
After producing a living polymer having a B+ structure, the polymer structure is expressed by the general formula (At Bg-AIB+-)-X (X residue of adipic acid dimethyl ester) by coupling with adipic acid dimethyl ester, Styrene content is 75% by weight, styrene block rate is 85%, M i
(G) is 10 g/l Qmin, M W / M of the polystyrene component incorporated into the block copolymer
A styrene-butadiene block copolymer with n of 1.3 was produced.

The dart impact value of the obtained block copolymer was 150 kg.
-cm, flexural modulus 9000 kg/c+fl.

Pencil hardness 6B, Haze 3%, molding shrinkage rate 0.
It was less than 2%. [Effects] The block copolymer obtained by the method of the present invention is transparent and has excellent impact resistance and surface hardness, so it can be suitably used as a material for injection molding. In particular, the block copolymer obtained by the method of the present invention has less warpage when injection molded, and is therefore suitable for flat molded products, molded products with many flat plate parts, and large molded products. Injection molded products of block copolymers obtained by the method of the present invention can be used in various applications where injection molded products of general-purpose thermoplastic resins are used, such as toys, daily necessities, food containers, miscellaneous goods, and light electrical parts. can be used. The block copolymer obtained by the method of the present invention may be used as extrusion molded products such as sheets and films, as well as molded products thermoformed by vacuum, pressure, etc., specifically food containers and packaging, and blisters. It can also be used in a wide range of containers and packaging materials, such as packaging materials, packaging films for fruits and vegetables, and confectionery.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. The polymer structure has the general formula (a) (A-B)_n_+_1 (b) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (c) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Linear block copolymers represented by the general formula (D) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (N) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (G) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ A radial block copolymer represented by Indicates a polymer segment consisting of a hydrogen polymer portion and having a vinyl aromatic hydrocarbon content of 50% by weight or more, or a polymer segment consisting only of a vinyl aromatic hydrocarbon homopolymer portion, B is a conjugated A polymer segment consisting of a random copolymer portion and/or a conjugated diene polymer portion of a diene and a vinyl aromatic hydrocarbon, and having a vinyl aromatic hydrocarbon content of less than 50% by weight. n is 1 to 1. is an integer of 5. X represents a residue of a coupling agent or a residue of an initiator of a polyfunctional organolithium compound. The weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is 65/35 to 85/15 and the block rate of the vinyl aromatic hydrocarbon exceeds 88% by weight, or the weight ratio of the vinyl aromatic hydrocarbon to the conjugated diene is 75/15.
25 to 95/5, and the block rate of vinyl aromatic hydrocarbon is 70 to 80% by weight; (ii) the block copolymer is oxidized with di-tert-butyl hydroperoxide using osmium tetroxide as a catalyst; After decomposition, the vinyl aromatic hydrocarbon polymer component obtained by adding methanol to the decomposed product has a weight average molecular weight to number average molecular weight ratio of 1.2 to 2.0, and (iii) a melt flow index ( JIS K-6
870, under G conditions, temperature 200°C, load 5kg) 2-50g/10min. When producing a block copolymer resin in a hydrocarbon solvent using an organolithium compound as an initiator, the block rate of the vinyl aromatic hydrocarbon is changed to (a) a mixture of a vinyl aromatic hydrocarbon and a conjugated diene continuously. and/or (b) prepared by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene using a polar compound or a randomizing agent. Method for producing polymer resin.