JPS6028865B2 - Method for improving anisotropy of block copolymers - Google Patents

Description

Detailed Description of the Invention The present invention uses a specific styrenic hydrocarbon-conjugated Genflock copolymer to suppress anisotropy in the physical properties of molded products that occurs when injection molding, extrusion molding, etc. It provides a method for improving

Styrenic hydrocarbon-conjugated gene flock copolymers, typified by styrene-butadiene flock copolymers, are generally widely used as thermoplastic elastomers or as transparent impact-resistant polystyrenes. Among these, block copolymers containing 60 to 85% by weight of styrenic hydrocarbons are being used as transparent impact-resistant polystyrene, and are finding new applications in the extrusion field of sheets and films, and the injection molding field of containers. be. It is known that this styrenic hydrocarbon-conjugated Jen block copolymer can have various block structures, and generally,
There is S-B-S, and (has the structure of S-B4Si,
A block copolymer in which the styrenic hydrocarbon blocks represented by S have the same molecular weight is used.

The present inventors have developed various products. Among the block copolymers having a block structure, (B-S, nB-S2 or (S, oneB
The block copolymer has a structure of S2, where S2 is 55 to 90% by weight of the total styrenic hydrocarbon polymer blocks, and has higher impact resistance than block copolymers with other general structures. Since these so-called asymmetric block copolymers have an excellent balance of rigidity, we have been conducting various applied research on these so-called asymmetric block copolymers. However, this S2 accounts for 55 to 90% by weight of the total styrenic hydrocarbon polymer block.
The asymmetric block copolymer has the disadvantage that the physical properties during molding are extremely variable compared to block copolymers in which the styrenic hydrocarbon blocks have the same molecular weight. That is, when the asymmetric block copolymer used in the present invention is extruded into a sheet, it has high strength in the extrusion direction, but it is extremely easy to break in the direction perpendicular to extrusion, and when injection molded into a flat plate, it has a strong strength in the flow direction. There were drawbacks such as the Izod impact value differing by more than 5 times in the direction perpendicular to the flow.
Moreover, such defects were most noticeable when the proportion of S2 was 75 to 85% of the total styrenic hydrocarbon polymer block. The present inventors investigated various additives for the purpose of improving the anisotropy of this particular block copolymer.

However, simply adding a resin with low molding anisotropy did not improve the anisotropy. For example, when polystyrene was added, a phenomenon was observed in which impact resistance decreased while maintaining anisotropy. The present inventors further investigated many additives, and as a result found an extremely excellent anisotropy improver, and completed the present invention. That is, the present invention can be applied to the general formula (B-S, B-S2 or (S, B-S2), where B is a polymer block mainly composed of conjugated hydrogen, and S and S2 are styrenic hydrocarbon polymers. (n is an integer from 1 to 5), the terminal styrenic hydrocarbon polymer floc S2 of the polymer chain is 55 to 9% by weight of the total styrenic hydrocarbon polymer blocks; ,
The total styrenic hydrocarbon content of the block copolymer is 60
~85% by weight, and the number average molecular weight of the block copolymer is 30,000 to 250,000 based on the weight part of the styrenic hydrocarbon-conjugated Jen block copolymer 10,
Styrene-methacrylic acid ester copolymer 10-100
Styrenic hydrocarbon characterized by being blended in parts by weight.
This is a method for improving the anisotropy of conjugated Genflock copolymers.

The present invention will be specifically explained below. The block copolymer used in the present invention is represented by the following general formula.

(B-S, chinB-S2 or (S, 1BnanS2ko)
B is a polymer block mainly composed of conjugated diene, and may be a conjugated diene polymer or a conjugated diene-styrene hydrocarbon random copolymer.

S and S2 are styrenic hydrocarbon polymer blocks. n is an integer of 1 to 5, preferably 2 or less. When n is 6 or more, (BS, n
(S, 1B) each block is shredded, the cohesive force between the styrenic hydrocarbon polymer blocks in the polymer chain weakens, and the rigidity of the block copolymer decreases, making it difficult to put into practical use. In the block copolymer used in the present invention, the terminal styrenic hydrocarbon polymer blocks account for 5 of the total styrenic hydrocarbon polymer blocks.
It is necessary to account for 5 to 9% by weight, preferably 75 to 85% by weight.

If it is less than 55%, it is not included in the present invention because there is no point in making it substantially asymmetrical and there is no physical superiority over commonly used block copolymers.

The styrenic hydrocarbon content of the block copolymer used in the present invention, including the styrenic hydrocarbon copolymerized in the B block and the styrenic hydrocarbon polymer block, is preferably 60 to 85% by weight. is necessary.

If it is less than 6% by weight, the block copolymer has low rigidity and is not practical.

Moreover, if it exceeds 85% by weight, the impact resistance decreases, which defeats the purpose of the present invention. Here, the styrenic hydrocarbon block ratio (total styrenic hydrocarbon polymer block amount/total styrenic hydrocarbon content x 100) of the block copolymer of the present invention is 50% or more, which provides a balance between rigidity and impact resistance. It is preferably 70% or more, and more preferably 70% or more. The number average molecular weight of the block copolymer used in the present invention is 3000
It needs to be between 0 and 250,000.

If the number average molecular weight is less than 30,000, the mechanical strength of the block copolymer will decrease, and if it exceeds 250,000, the processability will be poor. The conjugated gen in the present invention has 4 carbon atoms.
~8, for example, 1,3-butadiene,
2-methyl-1,3-butadiene (isoprene), 2.
These include 3-dimethyl-1,3-butadiene, 1,3-bentadiene, 1,3-hexadiene, etc., and 1,3-butadiene and isoprene are preferably used.

These may be used not only as a single type but also as a mixture of two or more types. The styrenic hydrocarbons referred to in the present invention include, for example, styrene, o-, m-, or p-methylstyrene, Q
- Styrene derivatives such as methylstyrene and dimethylstyrene, one or a mixture of two or more of these being used.

The block copolymer of the present invention can be produced by a living anionic polymerization method.

The manufacturing conditions may be any conventionally known conditions. Further, the obtained block copolymer may be a complete block copolymer or a so-called gradually decreasing block copolymer, as long as it satisfies the requirements required by the present invention. The anionic polymerization initiator used to produce the block copolymer of the present invention may be any monofunctional compound.

Ordinary organic monolithium compounds, such as n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, r-butyllithium,
N-bentyllithium, methylcyclohexyllithium, etc. are preferably used. There is no particular problem with the solvent used to polymerize the block copolymer of the present invention as long as it does not inactivate the anionic polymerization initiator, and aromatic hydrocarbons such as benzene, ethylbenzene, toluene, and xylene, and cyclohexane are used. , alicyclic hydrocarbons such as methylcyclohexane, ethylcyclohexane, hexane, heptane,
Aliphatic hydrocarbons such as isobentane, dimethylbutane, methylbentane are preferred.

Furthermore, the desired structure of the block copolymer can be achieved by adding an appropriate amount of polar compound to the solvent to increase the polymerization rate, or by changing the copolymerization reactivity ratio between the conjugated diene and the styrene hydrocarbon. . Examples of polar compounds in this case include ethers such as tetrahydrofuran and ethyl ether, and tertiary amines such as triethylamine. The polymerization temperature during polymerization of the block copolymer of the present invention is -
4000~1500C, but generally 40~12
It is 0oo. The time required for polymerization is 30 minutes to 24 hours, but generally it is 1 hour to 1 hour. The atmosphere of the polymerization system is preferably replaced with an inert gas such as nitrogen gas. In addition, care must be taken to avoid contamination of the polymerization system with impurities that would deactivate the organolithium compound or active copolymer, such as water, oxygen, carbon dioxide gas, etc. Next, the styrene-methacrylic acid ester copolymer used in the present invention is obtained by a normal radical polymerization method, and is generally a styrene 30-
It is a copolymer of 95% by weight and 70 to 5% by weight of methacrylic acid ester, preferably one or more selected from methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

It is possible to obtain high transparency by selecting a combination of a styrene hydrocarbon-conjugated JenProc copolymer and a styrene-methacrylic acid ester copolymer that have similar refractive indexes. Even with different combinations, the improved heterogeneity of the present invention can be obtained, and the balanced impact resistance makes it possible to expand the range of application to many applications. The amount of the styrene-methacrylic acid ester copolymer needs to be 10 to 10 parts by weight based on 10 parts by weight of the styrene hydrocarbon-conjugated gene block copolymer.

If it is less than 1 part by weight, the effect of improving the anisotropy of the block copolymer will be small, and if it exceeds 10 parts by weight, the properties of the block copolymer will be significantly impaired.

The preferred amount of the styrene-methacrylate copolymer is 20 to 50 parts by weight. In the present invention, the styrene-methacrylic acid ester copolymer can be blended with the styrene hydrocarbon-conjugated denfrost copolymer by any method used in ordinary plastic blending. There is a method of making a slurry, and a common method is to feed a dry blend of Haberette to a straight extrusion molding machine, an injection molding machine, etc.

In the method of the present invention, when improving the anisotropy of the block copolymer by blending the styrene-methacrylate copolymer, various additives may be added to the extent that the effects of the present invention are not substantially impaired. It is possible to add additional ingredients.

Examples of additives include styrene resins such as polystyrene and impact-resistant polystyrene, common styrene-butadiene floc copolymers with a styrene content of 20 to 85% by weight, polymethacrylate ester resins, and various stable resins. agent, plasticizer, pigment, lubricant, filler, etc. The compound obtained by the method of the present invention has improved anisotropy of the specific block copolymer used in the present invention, and is suitable for sheets, films, or injection molded products that are prone to molding anisotropy. However, it can also be used for other blow molded products, injection blow molded products, etc.

Examples of the present invention are shown below, but these are intended to explain the present invention in detail and are not intended to limit the scope of the present invention.

Examples 1-2, Comparative Examples 1-4 A block copolymer having an S,1B-S cage structure was polymerized in cyclohexane using n-butyllithium as an anionic polymerization initiator.

Here, S, is 2% by weight polystyrene block, B is 2% by weight polybutadiene block, S2 is 6% by weight polystyrene flock, and M1 (G conditions) of the floc copolymer is 8. there were. Next, a block copolymer having a B, -S, -B2-S2 structure was polymerized in the same manner as above.

Here, B is 8% by weight polybutadiene flock, S
, is a 14% by weight polystyrene flock, B2 is a 22% by weight polybutadiene flock, S2 is a 5% by weight polystyrene block, and the flock copolymer M1 (
G condition) was 5. These block copolymers 10
0 parts by weight, 30 parts by weight of Estyrene MS-200 (manufactured by Nippon Steel Chemical Co., Ltd., trade name), which is a styrene-methyl methacrylate copolymer, was blended with 4 parts by weight. After mixing using an extruder at 20,000 yen, the kneaded material was injection molded into a flat plate of 130 mm x 13 mm x 3 mm using a 5 oz. injection molding machine at a molding temperature of 200 oC.

The gate used in the injection molding was a fan gate with a thickness of one rib. Flow direction of injection molding from the obtained flat plate
Test pieces of the test items shown in Table 1 were cut out in the direction perpendicular to the flow direction (horizontal), and their physical properties were measured. Results first
Shown in the table. Next, for comparison, each of the above block copolymers alone and a blend of each of the above block copolymers with 30 parts by weight of polystyrene (Styron 660 manufactured by Asahi Dow, trade name) were injection molded under the same conditions as above. The physical properties were measured.

These results are also shown in Table 1. Table 1 Examples 3 to 5, Comparative Examples 5 to 7 Three types of styrene-phthalene floc copolymers were polymerized in the same manner as in Example 1.

The block copolymers used in Example 3 were B-S and Kazuma-S.
2 structures, B. is 6% by weight, S. was 6% by weight, & was 34% by weight, S2 was 54% by weight, and M1 (G condition) of the floc copolymer was 5. The block copolymer used in Example 4 had an S,-B-S cage structure, and S, was 3
4% by weight, B is 15% by weight, S2 is 51% by weight,
M1 (G condition) of the flock copolymer was 6.

The block copolymer used in Example 5 was a block copolymer having a tapered portion obtained by simultaneously making butadiene and styrene exist in the polymerization system, and was
It had a structure represented by SS, -B2/S-S2.

Here, B, is 8% by weight, styrene taper copolymerized in the B part is 4% by weight, S, is 1% by weight, horse is 12% by weight, and styrene taper copolymerized in the & part is 12% by weight. %, S2 is 48% by weight, and M of the floc copolymer
1 (G condition) was 10. To 100 parts by weight of these block copolymers, 50 parts by weight of Sebian MAS-10 (manufactured by Daicel Chemical, trade name), which is a styrene-methyl methacrylate copolymer, was blended, and the 25-side? Knead, extrude and sheet form using an extruder at 20000,
A sheet having a thickness of 0.3 ribs was obtained.

From the obtained sheet, the direction of flow (vertical) and the direction perpendicular to flow (
Test pieces of the test items shown in Table 2 were cut out from each sample and their physical properties were measured. The results are shown in Table 2. Furthermore, for comparison, each of the block copolymers described above was formed into a sheet under the same conditions as above, and the physical properties were measured.

These results are also shown in Table 2. Table 2 Examples 6 to 9, Comparative Examples 8 to 11 A block copolymer having a B, one S, one B2-S2 structure was polymerized in the same manner as in Example 1.

where B is 1% by weight of polybutadiene floc, S.
is 15% by weight polystyrene flock, B2 is 15% by weight polybutadiene flock, S2 is 6% by weight polystyrene flock, and M1 (G
condition) was 12. Next, for comparison, block copolymers containing the same amounts of S and S2 were polymerized in the same manner as above.

B of this floc copolymer. The block and B block were the same as the above block copolymer, S and S2 were each 37.5% by weight polystyrene flock, and M1 (G condition) of the flock copolymer was 9. Sebian MAS-20, which is a styrene-methyl methacrylate copolymer, was added to 100 parts by weight of these block copolymers.
(manufactured by Dial Kagaku, trade name) was blended in various proportions, injection molded in the same manner as in Example 1, and the physical properties were measured. The results are shown in Table 3.

As is clear from the above Examples and Comparative Examples, the styrenic hydrocarbon-conjugated diene floc copolymer of the present invention is essentially Although it has high properties, its use has been limited due to its anisotropy during molding. However, by applying the method of the present invention, it is possible to improve the anisotropy while maintaining high properties. It is a very unique phenomenon that this improvement could not be achieved at all with polystyrene, which has conventionally been commonly blended into styrene-butadiene block copolymers, and can only be achieved with styrene-methacrylic acid ester copolymers. It is believed that this invention can greatly contribute to expanding the applications of the identified styrenic hydrocarbon-conjugated Genblock copolymer.

Table 3

Claims (1)

[Claims] 1 General formula (B-S_1)_n-B-S_2 or (S_1-B)
__n-S_2 (in the formula, B represents a polymer block mainly composed of a conjugated diene, S_1 and S_2 represent a polymer block composed of styrenic hydrocarbons, and n is an integer from 1 to 5), and The terminal styrenic hydrocarbon polymer block S_2 of the coalescing chain is 55 to 90% by weight of the total styrenic hydrocarbon polymer block, and the total styrenic hydrocarbon content of the block copolymer is 60 to 85% by weight. ,
The number average molecular weight of the block copolymer is 30,000 to 250
A styrenic hydrocarbon-conjugated diene block copolymer characterized in that 10 to 100 parts by weight of a styrene-methacrylic acid ester copolymer is blended to 100 parts by weight of a styrene hydrocarbon-conjugated diene block copolymer of 000. Method for improving anisotropy of polymers.