JPH02113007A - Impact-resistant block copolymer - Google Patents

Abstract

PURPOSE:To obtain the subject copolymer having plural vinyl aromatic hydrocarbon polymer blocks containing isoprene polymer blocks and terminal parts with a specific composition and molecular weight and high impact resistance and strength without deteriorating transparency and melt fluidity. CONSTITUTION:The objective copolymer, obtained by filling a solvent, such as cyclohexane and THF, in an autoclave, adding, n-butyllithium, etc., and then a vinyl aromatic hydrocarbon (e.g.-styrene), polymerizing the resultant mixture, successively adding and polymerizing isoprene and the vinyl aromatic hydrocarbon and having (A) at least 2 polymer blocks consisting essentially of the vinyl aromatic hydrocarbon and (B) at least one polymer block consisting essentially of isoprene with 65-90wt.% content of the component (A) in the whole copolymer, 100,000-500,000 number-average molecular weight and >=1 blocks of the component (A) in the copolymer terminals. The content of the vinyl aromatic hydrocarbon thereof is 55-75wt.% based on the vinyl aromatic hydrocarbon in the whole copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a block copolymer with excellent impact resistance.

[Prior Art] Currently, there is a demand for thermoplastic resins with well-balanced physical properties such as transparency, impact resistance, high flex life, and tensile strength.
Styrene-butadiene block copolymers with high styrene content provide some balance. Recently, there has been a desire to develop resins with better impact resistance without sacrificing transparency and melt flowability, and in order to improve impact resistance, it is necessary to increase the butadiene content. Methods of increasing the molecular weight of polymers have been considered. However, increasing the butadiene content in the polymer lowers the rigidity of the polymer and deteriorates its transparency when blended with polystyrene. In addition, when the average molecular weight of the polymer is increased, the block copolymer has poor melt fluidity during processing and molding as a thermoplastic resin, making molding defects more likely to occur, making it necessary to set the molding temperature higher. . However, if the molding temperature is increased, a problem arises in that various physical properties deteriorate due to thermal deterioration of the polymer.

As described above, the above-mentioned physical properties have many contradictory elements and have not yet been fully satisfactory. In addition, as a method for introducing high molecular weight polymers without sacrificing melt fluidity,
A method is known in which an initiator is added in portions during polymerization and a low molecular weight polymer is mixed in (Japanese Patent Publication No. 59-52171).
.

In this method, it is possible to improve melt fluidity by incorporating a low-molecular polymer, but it has not been possible to completely avoid the effects of the low-molecular polymer on polymer strength such as impact resistance.

[Problems to be Solved by the Present Invention] As a result of intensive study on the above-mentioned problems, the present inventors have found that
Changing the butadiene part of the block copolymer to isoprene,
The inventors have discovered that a block copolymer with a specific structure can significantly improve polymer strength such as impact resistance without sacrificing melt fluidity, leading to the present invention.

[Means for solving the problem] The present invention has at least two polymer blocks A mainly composed of vinyl aromatic hydrocarbons and at least one polymer block B mainly composed of isoprene, A block copolymer in which the content of a vinyl aromatic hydrocarbon component in the polymer is 65 to 90% by weight, the total copolymer has a number average molecular weight of 1oo, ooo to 500.000, and The polymer has at least one polymer block A at the end thereof, and the vinyl aromatic hydrocarbon content of any one polymer block A is 55 to 75% by weight of the vinyl aromatic hydrocarbon of the entire block copolymer. % of the impact-resistant block copolymer.

Examples of the polymer structure of the block copolymer used in the present invention include those represented by the following formula.

(A-B) -A, (A-B)n [(A-B)] -X.

m[(AB)-A]-Xnm (wherein, A represents a vinyl aromatic hydrocarbon polymer block, and B represents an isoprene polymer block.

X represents a residue of a coupling agent.

n preferably represents an integer of 1 to 5, more preferably 1 to 4, particularly preferably 1 to 3, and m represents an integer of 2 or more, preferably 2 to 6, still more preferably 2 to 4. ) The block copolymer of the present invention can be produced by a generally known sequential polymerization method. That is, add ether or tertiary amine into a hydrocarbon solvent, use organolithium as an initiator, add vinyl aromatic hydrocarbon, isoprene, and vinyl aromatic hydrocarbon in this order, and then add as many times as necessary. For example, 0 to 8 times, preferably 0 to 6 times,
Additions of isoprene and vinyl aromatic hydrocarbons can be repeated. After each addition, polymerization is continued allowing sufficient time for the reaction to complete. Thereafter, if necessary, a polyfunctional processing agent can be added and the living polymer can be subjected to a coupling reaction.

When producing the block copolymer, the polymerization temperature range is usually 0 to 150°C, preferably 30 to 120°C,
Within this range, it can be obtained by isothermal polymerization or adiabatic polymerization.

The vinyl aromatic hydrocarbons used in the present invention include styrene, α-methylstyrene, p-methylstyrene, m-
Methylstyrene, 0-methylstyrene, dimethylstyrene, vinylnaphthalene, etc. can be used. Among these, styrene is preferably used.

Hydrocarbon solvents include cyclopentane, cyclobexane, benzene, ethylbenzene, xylene, pentane,
Hexane, heptane, butane, etc. may be used alone or in mixtures.

Examples of organic lithium compounds include n-butyllithium, 5
ec-butyllithium, tert-butyllithium, n
-hexyllithium, 1so-hexyllithium, phenyllithium, naphthyllithium, etc., and are used in a proportion of 0.04 to 0.50 parts by weight per 100 parts by weight of monomer.

As the ether or tertiary amine, ether compounds such as tetrahydrofuran, diethyl ether, anisole, dimethoxybenzene, ethylene glycol dimethyl ether, triethylamine, N-dimethylaniline, and pyridine, and tertiary amine compounds are used.

As the polyfunctional treatment agent, epoxidized soybean oil, epoxidized linseed oil, epoxidized polybutadiene, diethyl adipate, triethyl citrate, silicon tetrachloride, tin tetrachloride, carbon tetrachloride, etc. can be used.

The vinyl aromatic hydrocarbon contained in the block copolymer is 65 to 90% by weight, preferably 70 to 90% by weight, but if the vinyl aromatic hydrocarbon is 65% by weight or less,
This is not preferred because the rigidity of the polymer decreases and at the same time, the transparency decreases when blended with polystyrene. Moreover, if it exceeds 90% by weight, the impact resistance will be insufficient when blended with polystyrene.

In addition, the number average molecular weight is 100,000 to 500°000
However, there is a slight difference in melt fluidity between the linear type and the branched type. For linear type, preferably 10
0,000 to 300,000, preferably 12o for branched types.

000 to 400,000. Number average molecular weight is 100
．． 000 or less, no effect on impact resistance is seen, and 500,
If it is more than 000, melt fluidity is poor and processing and molding become difficult.

In preparing the polymer of the present invention, it is necessary to react initially or finally 55 to 75% by weight, preferably 57 to 70% by weight of the total amount of vinyl aromatic hydrocarbon used. If it is less than 55% or more than 75%, the effect of improving impact resistance will be small. Further, even if a vinyl aromatic hydrocarbon within this range is used in the process, the effect of improving impact resistance is small, which is not preferable.

[Effects of the Invention] The block copolymer of the present invention is intended to improve polymer strength such as impact resistance without reducing transparency and melt flowability, so it can be used alone or mixed with polystyrene. It can be used as a molding material for various molded products. In other words, from sheets and films to food containers and packaging,
It can be suitably used for blister packaging materials, packaging films, etc., and also for toys, daily necessities, miscellaneous goods, etc. by injection molding, blow molding, etc.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited unless it goes beyond the gist of the present invention.

Examples 1 to 3 4500 g of microhexane and 1 g of tetrahydrofuran were charged into a washed and dried autoclave equipped with a stirrer and a jacket under a nitrogen atmosphere, and then the internal temperature was raised to 70°C. Next, a hexane solution containing n-butyllithium in the amount shown in Table 1 was added, followed by 450 g of styrene. After polymerizing for 60 minutes, 80 g of isoprene was added and polymerization was continued for 60 minutes again. After that, 100g of styrene,
80g of isoprene 100g of styrene, 80g of isoprene
100 g of g1 styrene were added every 60 minutes. The polymerization conversion immediately before each addition was substantially 10,026. Further, as a result of continuing the polymerization for 60 minutes after the last addition of styrene, the polymerization conversion rate was substantially 100%. During the polymerization, the temperature was constantly adjusted to 70°C.

After the polymerization was completed, 2,6-sheet tert-butyl p-cresol was added to the polymer solution, and then cyclohexane was removed by heating to obtain a block copolymer.

Comparative Examples 1 to 2 Polymerization was carried out using the same recipe as in Examples 1 to 3 except that isoprene was replaced with butadiene.

Comparative Examples 3 to 4 Polymerization was carried out using the same formulation as in Examples 1 to 3 and the amount of n-butyllithium shown in Table 1.

Examples 4 to 6 Polymerization was carried out using n-butyllithium in the amount shown in Table 2 using the same recipe as in Examples 1 to 3, and 60 minutes after the final addition of styrene, polyfunctional terminal treatment was performed in the amount shown in Table 2. Add agent, 60
The coupling reaction was carried out for 1 minute, and polymers were obtained using the same formulation as in Examples 1 to 3.

Comparative Examples 5 to 6 Polymerization was carried out using the same recipe as in Examples 4 to 6 except that isoprene was replaced with butadiene.

Comparative Examples 7 to 8 Polymerization was carried out using the same formulation as in Examples 4 to 6 and the amount of n-butyllithium shown in Table 2.

Example 7 The monomer was added to styrene 4 using the same recipe as Examples 1 to 3.
00g, 80g of isoprene, 150g of styrene, 80g of isoprene, 100g of styrene.

Polymerization was carried out in the following order: 80 g of isoprene and 100 g of styrene.

Example 8 The monomer was added to styrene 4 using the same recipe as Examples 1 to 3.
Polymerization was carried out in the following order: 90 g of isoprene, 80 g of isoprene, 100 g of styrene, 80 g of isoprene, 80 g of styrene, 80 g of isoprene, and 80 g of styrene.

Example 9 The monomer was added to styrene 5 using the same recipe as Examples 1 to 3.
Polymerization was carried out in the following order: 60 g of isoprene, 80 g of isoprene, 70 g of styrene, 80 g of isoprene, 60 g of styrene, 80 g of isoprene, and 60 g of styrene.

Comparative Example 9 Addition of monomer to styrene 3 using the same formulation as Examples 1 to 3
40 g, 80 g of isoprene, 140 g of styrene, 80 g of isoprene, 140 g of styrene.

Polymerization was carried out in the following order: 80 g of isoprene and 130 g of styrene.

Comparative Example 10 Addition of monomer to styrene 6 using the same formulation as Examples 1 to 3
Polymerization was carried out in the following order: 00 g of isoprene, 80 g of isoprene, 50 g of styrene, 80 g of isoprene, 50 g of styrene, 80 g of isoprene, 50 g of styrene.

Example 10 The monomer was added to styrene 4 using the same recipe as Examples 1 to 3.
Polymerization was carried out in the following order: 00 g of isoprene, 160 g of isoprene, 150 g of styrene, and 12,100 g of smethane.

Example 11 Addition of monomer to styrene 5 using the same recipe as Examples 1 to 3
Polymerization was carried out in the following order: 00 g, 120 g of isoprene, 150 g of styrene, 120 g of isoprene, and 100 g of styrene.

Example 12 The monomer was added to styrene 6 using the same recipe as Examples 1 to 3.
Polymerization was carried out in the following order: 00g of isoprene, 60g of isoprene, 150g of styrene, 60g of isoprene, 150g of styrene.

Comparative Example 11 Addition of monomer to styrene 4 using the same formulation as Examples 1 to 3
Polymerization was carried out in the following order: 00 g, 250 g of isoprene, 100 g of styrene, 200 g of isoprene, and 100 g of styrene.

Comparative Example 12 Addition of monomer to styrene 6 using the same recipe as Examples 1 to 3
Polymerization was carried out in the following order: 00g of isoprene, 45g of isoprene/250g of styrene, and 45g of isoprene/100g of styrene.

Example 3 The monomer was added to styrene 4 using the same recipe as Examples 1 to 3.
Polymerization was carried out in the following order: 90 g of isoprene, 240 g of isoprene, and 260 g of styrene.

Example 14 Addition of monomer to styrene 4 using the same formulation as Examples 1 to 3
Polymerization was carried out in the following order: 90 g of isoprene, 80 g of isoprene, 130 g of styrene, 80 g of isoprene, 130 g of styrene, and 80 g of isoprene.

Example 15 Polymerization was carried out using the same recipe as in Examples 1 to 3, adding monomers (1) 410 g of styrene, (2) 48 g of isoprene, (1) 68 g of styrene, and then repeating (1) and (4) four times.

Comparative Example 13 Addition of monomer to styrene 7 using the same formulation as Examples 1 to 3
Polymerization was carried out in the following order: 5 g of isoprene, 80 g of isoprene, 450 g of styrene, 80 g of isoprene, 225 g of styrene, and 80 g of isoprene.

Comparative Example 14 Polymerization was carried out using the same recipe as in Examples 1 to 3, adding the monomers in the following order: (1) 110 g of styrene, (2) 30 g of isoprene, and then repeating (1) and (2) 6 times.

The above results are shown in the table below.

The physical properties of the obtained block copolymer were evaluated by the following method.

[Analysis/evaluation method] Number average molecular weight: ■ Column G manufactured by Tosoh using GPC
400OHXL MI value: JIS K-7210 200°C 5.0 kg load method Izot impact: JIS K-7110 Transparency/HA
ZE: JIS K-7105 Moldability/Appearance: Judged based on the appearance of a test piece during an injection molding test.

○: No scratches or flow marks are observed on the test piece.

Δ: Scratches and flow marks were observed on less than half of the test pieces.

×: Scratches, flow marks, and molding defects were observed throughout the test piece.

Claims (1)

[Claims] (1) It has at least two polymer blocks A mainly composed of vinyl aromatic hydrocarbons and at least one polymer block B mainly composed of isoprene, and the vinyl aromatic hydrocarbon component in the entire copolymer A block copolymer having a content of 65 to 90% by weight, the total number average molecular weight of the copolymer is 100,000 to 500,000, and at least polymer block A is present at the end of the copolymer. I have one,
An impact-resistant block copolymer characterized in that the vinyl aromatic hydrocarbon content of any one polymer block A is 55 to 75% by weight of the vinyl aromatic hydrocarbon in the entire block copolymer. .