JPH0617430B2 - Block copolymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel vinyl aromatic compound-conjugated diene block copolymer, and more specifically, a non-elastomeric vinyl resin having transparent ends and balanced impact strength, tensile strength and elongation. The present invention relates to a block copolymer having an aromatic compound block and a mainly aromatic elastomer block of a vinyl aromatic compound and a conjugated diene mainly containing a conjugated diene, and a method for producing the block copolymer.

Recently, there is an increasing demand in various fields for a thermoplastic resin that is transparent and has a good balance of impact strength, tensile strength and elongation.

A linear block copolymer composed of a vinyl aromatic compound and a conjugated diene is known in the technical field of anionic polymerization. For example, JP-B-47-28915, JP-B-47-3252, JP-B-48-2423 and JP-B-48-2323. 48-20038. However, the block copolymers obtained by these methods are not yet sufficiently satisfactory in terms of impact strength, tensile strength and elongation balance.

Therefore, the present inventors have arrived at the present invention as a result of intensive studies to obtain a block copolymer having a good balance of impact strength, tensile strength and elongation. That is, the present invention relates to a vinyl aromatic compound-conjugated diene block copolymer having a vinyl aromatic compound content of more than 55% by weight and 95% by weight or less, which is obtained by polymerizing an organolithium compound as an initiator in a hydrocarbon solvent. The copolymer has the general formula A-B-A (wherein A is a vinyl aromatic compound polymer block, and the total amount of A at both ends is 70% of the total amount of the vinyl aromatic compound).
Is a copolymer of a conjugated diene and a vinyl aromatic compound, and the B portion has (a) 2 to 10 tapered blocks in which the vinyl aromatic compound is gradually increased,
(b) Weight ratio of vinyl aromatic compound / conjugated diene is 3 to 8
It is 5 / 97-15. ) And the amount of the chain of 1 to 4 chained vinyl aromatic compounds in the monomer unit is 5% of the total vinyl aromatic compound content.
It is a block copolymer characterized by being -25% by weight. The molecular weight of this polymer is as described below.

The block copolymer of the present invention has a vinyl aromatic compound of 55
More than 95% by weight but less than 95% by weight, preferably 60 to 90% by weight
Is. If the vinyl aromatic compound content is 55% by weight or less, the hardness is not sufficient, and if it exceeds 95% by weight, the impact strength is poor.

The block copolymer of the present invention is characterized in that in the general formula ABA, the B portion has a vinyl aromatic compound in a specific range,
Furthermore, the number of tapered blocks is in a specific range, and the block copolymer is a copolymer having a chain distribution of vinyl aromatic compounds in a specific range. These features make it transparent and significantly improve the balance of impact strength, tensile strength and elongation.

That is, the content of the vinyl aromatic compound in the B portion of the block copolymer of the present invention is 3 to 85% by weight, preferably 10 to 55% by weight, and the vinyl aromatic compound in the A portion is 70% by weight of all the vinyl aromatic compounds. ~ 97% by weight, preferably 75 ~
90% by weight. When the content of the vinyl aromatic compound in the B portion is less than 3% by weight, the tensile strength is poor, and when it exceeds 85% by weight, the elongation is insufficient. Further, the portion B is composed of a tapered block in which the vinyl aromatic compound increases, and the number of the tapered block is 2 to 10, preferably 2 to 6. If the number of taper blocks is less than 2, elongation is poor and 1
If it exceeds 0, the impact resistance and tensile strength are poor.

The chain distribution of the vinyl aromatic compound in the block copolymer is such that the amount of the chain of the vinyl aromatic compound having 1 to 4 chained monomer units is 5 to 25% by weight, preferably 10 to 10% by weight of the total vinyl aromatic compound content. It is 20% by weight. If the chain of 4 or less is less than 5% by weight, the elongation is poor, and if it exceeds 25% by weight, the impact strength is poor.

The block copolymer of the present invention can be produced by the following method.

That is, ether or tertiary amine is added to a hydrocarbon solvent, and an organolithium compound is used as an initiator. (1) First, a vinyl aromatic compound is used in an amount of 20-4
After polymerizing 5% by weight, preferably 25-40% by weight, after the polymerization reaction is substantially completed, (2) conjugated diene 15-97% by weight and vinyl aromatic compound 3-
The 85% by weight mixture is polymerized in 2 to 10 portions, and if necessary, the conjugated diene is added once to polymerize.

(3) Finally, a method of polymerizing the vinyl aromatic compound in an amount of 20 to 45% by weight, preferably 25 to 40% by weight, based on the total amount of monomers used can be used.

In the step of polymerizing the mixture of the conjugated diene and the vinyl aromatic compound in 2 to 10 times, it is preferable that the amount of the monomer used in each time is about the same, and the amount of the monomer added in each time is almost 100. % Polymerization is desirable.
As a method of adding the monomer in two to ten times, a method of adding a monomer mixture, a method of simultaneously adding a conjugated diene and a vinyl aromatic compound, or the like is used.

The vinyl aromatic compound-conjugated diene copolymer having a preferable vinyl aromatic compound chain distribution can be obtained by adding an ether or a tertiary amine to a hydrocarbon solvent and polymerizing. The addition of ethers or tertiary amines increases the chain amount of vinyl aromatic compounds 1 to 4, which is 5 to 25% of the vinyl aromatic compound content.
The weight% is preferable, and more preferably 10 to 25% by weight. If it is less than 5% by weight, the elongation is poor, and if it exceeds 25% by weight, the impact strength is poor.

From the viewpoint of controlling the chain distribution of the vinyl aromatic compound, it is essential in the step (2) that the amount of ether or tertiary amine used is 0.005 to 5 parts by weight per 100 parts by weight of the monomer, preferably It is 0.005-0.5 parts by weight.

As the vinyl aromatic compound used in the present invention, styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, n-tert-butylstyrene, dimethylstyrene, vinylnaphthalene and the like can be used. . Of these, styrene is preferred. As the conjugated diene, butadiene, isoprene, piperylene, etc. can be used. Of these, butadiene is preferred.

The block copolymer of the present invention has a weight average molecular weight of 10,000 to
It is 800,000, preferably 50,000 to 500,000. The weight average molecular weight of the A portion is 3,000 to 150,000, and the weight average molecular weight of the B portion is 5,000 to 200,000.

The block copolymer of the present invention can be obtained by either an isothermal polymerization method or an adiabatic polymerization method. The preferred polymerization temperature range is 30 to 120.
℃.

As the hydrocarbon solvent used in the production of the block copolymer of the present invention, for example, cyclopentane, cyclohexane,
Benzene, ethylbenzene, xylene and mixtures thereof with pentane, hexane, heptane, butane and the like are used.

Examples of the organic lithium compound include n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n
-Hexyl lithium, iso-hexyl lithium, phenyl lithium, naphthyl lithium, etc.
It is used at 0.04 to 1.0 part by weight per part by weight.

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

The block copolymer of the present invention may be used alone or in a blend with polystyrene, 1,2-polybutadiene or the like, if necessary, for food containers, toys, daily necessities, footwear, automobile parts, electric appliance parts.

In addition, the use of the block copolymer of the present invention covers a wide range of areas, and if examples thereof are shown, injection molded products such as footwear and containers, flow molded products such as toys and household products, compression products such as packing, sheets and plates. It can be suitably used for molded products and the like. Further, since it dissolves in a hydrocarbon solvent, it can be effectively used as an adhesive. Further, the block copolymer of the present invention can be used by mixing it with other rubber such as SBR or NBR, or plastic such as polystyrene to modify its physical properties. It can also be foamed and used for various purposes.

In the central portion of the copolymer of the present invention, the one having a large amount of vinyl aromatic compound exhibits a glassy hard property, which is used for a composition for a molded product in a lump or a sheet. it can.

Further, the block copolymer of the present invention is hydrogenated to have heat resistance,
The weather resistance can be improved. A hydrogenated block copolymer can also be used or a composition for each of the above applications.

Various measurements were made by the following methods.

Impact strength, tensile strength and elongation were measured according to JIS K6871.

The transparency test was based on ASTM D-1003.

The styrene chain was based on the method developed by Professor Tanaka of Agricultural Science and Technology (Proceedings of the Polymer Society of Japan, Vol. 29, No. 7, page 2055).

The hardness was measured on the R scale according to ASTM D-785.

The total styrene content was determined by the infrared method.

Example 1 5,000 g of cyclohexane and 1 g of tetrahydrofuran were charged into an autoclave equipped with a washing and drying stirrer and a jacket under a nitrogen atmosphere, and then the internal temperature was brought to 70 ° C.

Next, a hexane solution containing 0.64 g of n-butyllithium was added, and then 300 g of styrene was added, followed by polymerization for 60 minutes. The polymerization conversion of styrene was 100%. Then styrene 50
and a mixture of 125 g of butadiene were added and polymerization was carried out for 60 minutes. The polymerization conversion rate of styrene and butadiene was 100%. Further, this operation was repeated twice. Then butadiene
125 g was added and polymerized to a polymerization conversion rate of 100%. After that, 300 g of styrene was further added and polymerization was carried out for 60 minutes. The conversion rate was 100%.

During the polymerization, the temperature was constantly adjusted to 70 ° C. After completion of the polymerization, 2,6-di-tert-butyl p-cresol was added to the polymer solution, and then cyclohexane was removed by heating to obtain a block copolymer.

Examples 2 to 3 and Comparative Examples 1 to 5 Polymerization was carried out in the same manner as in Example 1 using the predetermined amounts of styrene, butadiene, tetrahydrofuran etc. shown in Table-1.

Table 2 shows the molecular characteristics of the block copolymer.

Table 3 shows the physical property evaluation results of the block copolymer.

Example 1: An example in which the total bound styrene was 60%, the bound styrene in the B portion was 23%, and the number of additions of the monomer in the B portion was 4 times.

Example 2: An example in which the total bound styrene was 90%, the bound styrene in the B portion was 64%, and the number of additions of the monomer in the B portion was 6 times.

Example 3: Example using paramethylstyrene instead of styrene.

An example in which the total amount of bound paramethylstyrene was 75%, the amount of bound paramethylstyrene in the B portion was 37%, and the number of additions of the monomer in the B portion was twice.

Comparative Example 1: An example in which the total bound styrene was 40%.

 〃 2: An example in which the total bound styrene is 98%.

〃 3: Example of adding tetrahydrofuran in a large excess.
(6.0g / 100g monomer-) 〃 4: Example where the number of times of addition of the monomer of B part was 12 times.

 〃 5: Example in which the number of times of addition of the monomer in the B portion is set to 1 time.

As shown in Table-3, Examples 1 to 3 are compared with Comparative Examples 1 to 5,
It has an excellent balance of impact strength, tensile strength and elongation at break.

Application Example 1000 g of the block copolymer of Example 1 was added to cyclohexane 50
After dissolving in 00g and adding 13g of tetrahydrofuran,
100 ml of cyclohexane solution containing 2.5 g of nickel acetylacetone and 300 ml of cyclohexane solution containing 40 g of triisobutylaluminum were added, and the mixture was 15 kg / cm ² , 100 ° C.
The reaction was carried out for 60 minutes. After completion of the reaction, the polymer was washed several times with an aqueous hydrochloric acid solution, and then the solvent was removed in the same manner as in Example 1 to obtain a polymer. Polymer pulling speed is 245 kg / cm ² , elongation is 650
%, Hardness (JIS-A) was 97.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum of Example 1, and FIG. 2 is a chain distribution curve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Oshima 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (72) Inventor Yoshito Yoshimura 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (2)

[Claims] 1. A vinyl aromatic compound-conjugated diene block copolymer having a vinyl aromatic compound content of more than 55% by weight and not more than 95% by weight, which is obtained by polymerizing an organolithium compound as an initiator in a hydrocarbon solvent. The copolymer has the general formula A-B-A (where A is a vinyl aromatic compound polymer block, and the total amount of A at both ends is 70% of the total amount of the vinyl aromatic compound).
~ 97 wt%, and the weight average molecular weight of A is 3,000
Is 150,000, B is a copolymer of a conjugated diene and a vinyl aromatic compound, and its weight average molecular weight is 5,000 to 200,000.
Wherein the B portion has (a) 2 to 10 tapered blocks in which the vinyl aromatic compound gradually increases, and (b) the vinyl aromatic compound / conjugated diene weight ratio is 3 to
85 / 97-15. ), The amount of the chain of 1 to 4 vinyl aromatic compounds linked in monomer units is 5 to 5% of the total vinyl aromatic compound content.
25% by weight and a weight average molecular weight of 10,000 to 800,
A polymer characterized by being 000. 2. A vinyl aromatic compound-conjugated diene block copolymer having a vinyl aromatic compound content of more than 55% by weight and not more than 95% by weight, which is obtained by polymerizing an organic lithium compound as an initiator in a hydrocarbon solvent. The copolymer has the general formula A-B-A (where A is a vinyl aromatic compound polymer block, and the total amount of A at both ends is 70% of the total amount of the vinyl aromatic compound).
~ 97 wt%, and the weight average molecular weight of A is 3,000
Is 150,000, B is a copolymer of a conjugated diene and a vinyl aromatic compound, and its weight average molecular weight is 5,000 to 200,000.
Wherein the B portion has (a) 2 to 10 tapered blocks in which the vinyl aromatic compound gradually increases, and (b) the vinyl aromatic compound / conjugated diene weight ratio is 3 to
85 / 97-15. ), The amount of the chain of 1 to 4 vinyl aromatic compounds linked in monomer units is 5 to 5% of the total vinyl aromatic compound content.
25% by weight and a weight average molecular weight of 10,000 to 800,
A method for producing a copolymer of 000, wherein an organolithium compound is used as an initiator in a hydrocarbon solvent, and (1) first, a vinyl aromatic compound is used in an amount of 20% of the total amount of monomers.
After the polymerization reaction is substantially completed, (2) a mixture of 15 to 97% by weight of the conjugated diene and 3 to 85% by weight of the vinyl aromatic compound is divided into 2 to 10 times and all the monomers are divided. Polymerization in the presence of 0.005 to 5 parts by weight of ether or tertiary amine per 100 parts by weight (3) Finally, vinyl aromatic compound is polymerized in an amount of 20 to 45% by weight based on the total amount of the monomers used. Method for producing polymer.