JPH0529645B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a block copolymer having excellent impact resistance, rigidity, low-temperature stretchability, environmental damage resistance, and hollow formation. [Prior Art] It has been known that block copolymers having various properties can be obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene using an organolithium compound as a catalyst. In particular, in the case of block copolymer resins with a relatively high content of vinyl aromatic hydrocarbons, block copolymers that are transparent and have excellent impact resistance can be obtained by selecting conditions; Recently, there has been a tendency for its usage to increase, mainly in the field of food packaging containers. Methods for producing such block copolymer resins include, for example, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 3252-1972, Japanese Patent Publication No.
No. 47-28915, Special Publication No. 48-4106, Special Publication No. 58-
A method disclosed in Publication No. 11446 and the like has been proposed. However, although these methods yield transparent products with relatively good impact resistance, they are inferior in low-temperature stretchability and environmental damage resistance, and the block copolymers obtained by these methods cannot be stretched and heated. When used as a heat-shrinkable film, there are problems such as low shrinkage rate at low temperatures and cracks in the film when covering articles such as glass bottles with the heat-shrinkable film, and improvements are desired. ing. [Problems to be Solved by the Invention] The present invention aims to improve impact resistance, stiffness, low-temperature stretchability, and environmental damage resistance by elucidating the structure of a block copolymer required to improve these physical properties. ,
The present invention provides a method for producing a block copolymer with improved various physical properties. [Means and effects for solving the problem] The present invention provides a vinyl aromatic hydrocarbon polymer with a polymer segment in which the weight ratio of vinyl aromatic hydrocarbon to conjugated diene exceeds 75/25 and is 90/10 or less. This is based on the discovery that the above problems can be solved by creating a structure that exists adjacent to the segment. That is, in the present invention, in a hydrocarbon catalyst, an organolithium compound is used as an initiator, and the polymer structure is (a) A-B-C (b) A-B-C-A (c) A-B-C- B-A (d) B-A-C-B-A (e) C-B-A-C-B-A (f) A-C-B-A-C-B-A (g) A- C-B-A-B-C-A (chi) (A-B-C) _o+1 ---X (li) (B-A-C) _o+1 ---X (nu) (A -B-C-A) _o+1 ---X (ru) (A-B-C-B-A) _o+1 ---X (wo) (B-A-C-B) _o+1 ---X (W) (B-A-B-C) _o+1 ---X (In the above formula, A means that the weight ratio of vinyl aromatic hydrocarbon and conjugated diene exceeds 90/10, and 100/ 0 or less, B is a vinyl aromatic hydrocarbon to conjugated diene weight ratio of more than 75/25;
Polymer segment in the range of 90/10 or less, C is a vinyl aromatic hydrocarbon to conjugated diene weight ratio of 75/25
Below, polymer segments in the range of 0/100 or more are shown. X represents a residue of a coupling agent or a residue of a polyfunctional organolithium compound. n is an integer from 1 to 5. ) with a number average molecular weight of 30,000~
500,000, in which the overall weight ratio of vinyl aromatic hydrocarbon to conjugated diene is from 60/40 to 95/5, (a) vinyl in the monomer charged for forming each segment; The aromatic hydrocarbon content is within the range of the vinyl aromatic hydrocarbon content corresponding to each of the above polymer segments, and (b) the total monomer amount (A') of the portion corresponding to segment A in all monomers charged is 20 to 80 parts by weight, the total amount of monomers (B') in the part corresponding to segment B is 10 parts by weight or more, the total amount of monomers (C') in the part corresponding to segment C is 10 parts by weight or more, the combination of B' and C' The total amount is 20 to 80 parts by weight (however,
A′+B′+C′=100 parts by weight), (c) Segment B is a mixture of vinyl aromatic hydrocarbon and conjugated diene having the above composition ratio, which is continuously fed into the polymerization system () and polymerized. and/or () based on 100 parts by weight of all monomers charged
The present invention relates to a method for producing a block copolymer, which is polymerized in the presence of 0.001 to 10 parts by weight of a polar compound or a randomizing agent, and is formed adjacent to segment A. Since the block copolymer obtained by the method of the present invention has excellent low-temperature stretchability, it can be easily uniaxially or biaxially stretched at low temperatures, and a film with excellent low-temperature shrinkability can be obtained. Since the heat-shrinkable film made from the block copolymer obtained by the method of the present invention has excellent shrinkability at low temperatures or in a short period of time even at high temperatures, it is It is suitable for packaging items that deteriorate or deform when heated, such as fresh foods and plastic molded items. Moreover, the heat-shrinkable film has excellent impact resistance and can be used as a covering for articles such as glass bolts, which are likely to have fragments scattered when broken. Furthermore, the above-mentioned heat-shrinkable film has excellent environmental damage resistance, and has the feature that it is difficult to break even if an article coated with the heat-shrinkable film is left in an outdoor environment with severe temperature changes. In particular, when the article to be coated is made of materials such as metal, porcelain, glass, polyester resin, etc., which have very different properties such as coefficient of thermal expansion and water absorption,
Conventional heat-shrinkable films had the disadvantage of poor environmental damage resistance after coating and cracks easily formed in the film, but the heat-shrinkable film obtained from the block copolymer obtained by the method of the present invention When a film is used, there is no such problem and it can withstand being left in the natural environment for a long time. Therefore, the above-mentioned heat-shrinkable film can be particularly suitably used for applications such as labels for containers made of the above-mentioned materials by taking advantage of such advantages. Moreover, the block copolymer obtained by the method of the present invention can be made into various molded products by injection molding or injection blow molding. Furthermore, films and sheets formed from the block copolymer obtained by the method of the present invention by methods such as extrusion molding and inflation molding can be used as they are, or can be further subjected to secondary processing by methods such as pressure forming and vacuum forming. It can be used for various purposes. Further, the block copolymer obtained by the method of the present invention has excellent blow moldability, and blow molded products with good surface gloss and transparency can be obtained. In general, block copolymers have poor blow moldability, and during molding, the molten barison itself may ripple or have shark skin (surging or melt fracture). When the melt flow is increased, the molten barison tends to sag due to its own weight (referred to as drawdown), but these problems are improved in the block copolymer obtained by the method of the present invention. The present invention will be explained in detail below. The block copolymer obtained by the method of the present invention has the polymer structure shown above and has a vinyl aromatic hydrocarbon content of more than 90% by weight, preferably 92 to 100% by weight, more preferably 100% by weight. % polymer segment A, and a polymer segment B having a vinyl aromatic hydrocarbon content of more than 75 wt.% and no more than 90 wt.%, preferably more than 80 wt.% and no more than 87 wt.%, and a vinyl aromatic hydrocarbon content of Polymer segment C having a hydrocarbon content of 75% by weight or less, preferably 60-0% by weight, more preferably 60-30% by weight
(When the vinyl aromatic hydrocarbon content is 0% by weight, the polymer segment corresponds to a conjugated diene homopolymer segment). It is. If the vinyl aromatic hydrocarbon content of segment A is less than 90% by weight, the rigidity will be poor;
If the vinyl aromatic hydrocarbon content of segment B is outside the above range, it is not preferable because low-temperature stretchability, environmental damage resistance, and blow moldability are poor. Moreover, when the vinyl aromatic hydrocarbon content of segment C exceeds 75% by weight, impact resistance is poor. The block copolymer obtained by the method of the present invention has an overall weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 60/40.
-95/5, preferably 65/35 - 90/10. If the amount of vinyl aromatic hydrocarbon is less than 60% by weight, the rigidity will be poor, and if it exceeds 95% by weight, the impact resistance will be poor, which is not preferable. Furthermore, the proportion of each segment in the block copolymer obtained by the method of the present invention is determined by the total amount of the portion corresponding to segment A (A').
is 20 to 80 parts by weight, preferably 30 to 70 parts by weight, the total amount (B') of the portion corresponding to segment B is 10 parts by weight or more, preferably 15 to 40 parts by weight, and segment C
The total amount of the parts corresponding to (C′) is 10 parts by weight or more, preferably 15 to 55 parts by weight, and the total amount of B′ and C′ is 20 to 80 parts by weight.
Parts by weight, preferably 30 to 70 parts by weight (However, A′+
B′+C′=100 parts by weight). If the ratio of A' or B'+C' deviates from the above range, the rigidity or impact resistance will be poor. Also, if B' is less than 10% by weight, low-temperature stretchability, environmental damage resistance, and blow moldability will be poor.
If C' is less than 10% by weight, it is not preferred because the impact resistance is poor. Furthermore, segment B must be adjacent to segment A. When segment B is not adjacent to segment A, low-temperature stretchability, environmental damage resistance, and blow moldability are poor. It could not have been foreseen from conventional knowledge that segment B would be extremely effective in imparting such performance. In addition, it is preferable that the blocking ratio of the vinyl aromatic hydrocarbon in segment A be more than 80% by weight, preferably 90% by weight or more, in order to obtain a block copolymer with excellent environmental damage resistance. In the block copolymer of the present invention, the reason why segment B exhibits an effective effect in terms of low-temperature stretchability is thought to be that the presence of segment B shifts the glass transition temperature of segment A to the lower temperature side. When the block copolymer is a styrene-butadiene block copolymer, the glass transition temperature due to the polystyrene block appears at about 90°C or higher when segment B is not present.
is present, below about 87°C, generally about 60°C to
Appears at 85℃. Therefore, by examining whether the glass transition temperature caused by the polystyrene block appears below about 87°C, it can be confirmed that the block copolymer is within the range defined by the present invention. The glass transition temperature referred to herein is the temperature determined from the inflection point of the dynamic elastic modulus (E') of dynamic viscoelasticity measured with a Vibron, for example, RheoViblon DDV-3 manufactured by Toyo Baldwin. The structure of the block copolymer obtained by the method of the present invention includes the following structures. (a) A-B-C (b) A-B-C-A (c) A-B-C-B-A (d) B-A-C-B-A (e) C-B-A -C-B-A (f) A-C-B-A-C-B-A (g) A-C-B-A-B-C-A (ch) (A-B-C) _{o+ 1} ---X (ri) (B-A-C) _o+1 ---X (nu) (A-B-C-A) _o+1 ---X (ru) (A-B-C -B-A) _o+1 ---X (wo) (B-A-C-B) _o+1 ---X (wa) (B-A-B-C) _o+1 ---X (In the above formula, ) The block copolymer obtained by the method of the present invention is
It may be a mixture of two or more block copolymers with different structures that satisfy the conditions specified in the present invention. Furthermore, when segments A, B, or C contain a copolymerized portion of a vinyl aromatic hydrocarbon and a conjugated diene, the distribution of the vinyl aromatic hydrocarbon in that portion may be uniform or tapered. Furthermore, segments A, B, or C are polymers that fall within the scope of each segment, and each segment contains two different polymers of vinyl aromatic hydrocarbons.
It may contain more than one. The number average molecular weight of the block copolymer obtained by the method of the present invention is from 30,000 to
500,000, preferably 50,000 to 350,000. In the present invention, vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-
Dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, etc.
A particularly common example is styrene. These may be used not only alone, but also as a mixture of two or more. Conjugated dienes include diolefins 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-pentadiene, 1,3
-hexadiene, etc., and particularly common ones include 1,3-butadiene and isoprene. These may be used not only alone, but also as a mixture of two or more. The block copolymer defined in 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, isopentane, heptane, octane, isooctane, cyclopentane,
Alicyclic hydrocarbons such as methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, or aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene can be used. Organolithium compounds are organic monolithium compounds in which one or more lithium atoms are bonded in the molecule, such as ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium. , hexamethylene dilithium, butadienyl dilithium, isoprenyl lithium, etc. The organolithium compound may be added in its entirety before polymerization, or may be added in portions during polymerization. In the method of the present invention, the monomer composition used to form each segment of the obtained block copolymer is within the vinyl aromatic hydrocarbon content range corresponding to each polymer segment. That is, in forming segment A, monomers in which the weight ratio of vinyl aromatic hydrocarbon to conjugated diene is more than 90/10 and less than 100/0,
In the formation of segment B, the weight ratio of vinyl aromatic hydrocarbon and conjugated diene exceeds 75/25,
In forming segment C, a monomer having a weight ratio of vinyl aromatic hydrocarbon to conjugated diene of 75/25 or less and a weight ratio of 0/100 or more is used. In addition, the amount of monomers charged for forming each segment is within the range of A' above as the total amount of monomers for forming segment A in the formation of segment A, and within the range of A' above as the total amount of monomers for forming segment B in the formation of segment B. In the case of forming segment C, the total amount of monomers for forming segment C is within the range of C'. There is no particular restriction on the method of feeding the monomers for forming segments A and C into the polymerization system, and they may be fed continuously into the polymerization system, the monomers may be fed all at once, or some of the monomers may be fed into the polymerization system. may be supplied in several portions. on the other hand,
The monomer for forming segment B is obtained by () continuously supplying a mixture of a vinyl aromatic hydrocarbon and a conjugated diene in the above composition ratio to a polymerization system and polymerizing it, and/or () 100 weight of total monomers charged. 0.001 for part
It is polymerized in the presence of ~10 parts by weight, preferably 0.01 to 5 parts by weight of a polar compound or randomizing agent, and is formed adjacent to segment A. In forming segment B, if the monomer supply method described in () above is not used under the conditions described in () above, the monomer may be supplied at once or a portion of the monomer may be supplied in several parts. Good too. In addition, when a mixture of a vinyl aromatic hydrocarbon and a conjugated diene is supplied to the polymerization system for polymerization, the supply form of the vinyl aromatic hydrocarbon and the conjugated diene is that the vinyl aromatic hydrocarbon and the conjugated diene are copolymerized and the main Any method may be used as long as the segment B that satisfies the requirements defined by the invention is formed. For example, the vinyl aromatic hydrocarbon and the conjugated diene may be mixed in advance and the mixture may be supplied to the polymerization system, or the vinyl aromatic hydrocarbon and the conjugated diene may be supplied to the polymerization system from separate supply ports. However, these monomers may be mixed and copolymerized at the same time in the polymerization system, or after one monomer is supplied in its entirety into the polymerization system, the other monomer may be added until the polymerization of that monomer is completed. It may be supplied into the polymerization system for copolymerization. Polar compounds and randomizing agents used in the method of the present invention include ethers, amines, thioethers, phosphoramides, alkylbenzesulfonates, potassium or sodium alkoxides, and the like. Examples of suitable ethers are dimethyl ether, diethyl ether, diphenyl ether and tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether. As the amines, in addition to tertiary amines such as trimethylamine, triethylamine, and tetramethylethylenediamine, cyclic tertiary amines can also be used. Phosphines and phosphoramides include triphenylphosphine and hexamethylphosphoramide. Randomizing agents include potassium or sodium alkylbenzene sulfonate, potassium or sodium butoxide, and the like. These polar compounds or randomizing agents may be added before the start of the polymerization reaction, or may be added before the polymerization of the segment B portion. The above requirements in the formation of segment B are extremely important in imparting low temperature stretchability and environmental damage resistance to the block copolymer. In the process of the invention, the polymerization temperature is generally -40
℃ to 150℃, preferably 40℃ to 120℃. The time required for polymerization varies depending on the conditions, but
Usually within 48 hours, particularly preferably within 1 to 48 hours.
It is 10 hours. Further, it is desirable to replace the atmosphere of the polymerization system with an inert gas such as nitrogen gas. The polymerization pressure is not particularly limited as long as it is within a pressure range sufficient to maintain the monomer and solvent in a liquid phase within the above polymerization temperature range. Furthermore, care must be taken to avoid contamination of the polymerization system with impurities that would inactivate the catalyst and living polymer, such as water, oxygen, carbon dioxide, and the like. The living polymer of the block copolymer obtained in this way is inactivated by adding a polymerization terminator such as water, alcohol, carbon dioxide, etc. in an amount sufficient to inactivate the active end. be done. At this time, by appropriately selecting a polymerization terminator such as reacting with carbon dioxide, alkylene oxide, alkylene sulfide, etc., terminals such as -OH, -SH, -COOH, -COCl, -
Block copolymers having various functional groups such as SO ₃ H and -C≡N at their ends can be obtained. If necessary, various stabilizers can be added to the block copolymer for the purpose of improving heat resistance, weather resistance, etc. Methods for recovering the block copolymer from the obtained block copolymer solution include, for example, recovering the block copolymer by precipitation using a precipitant such as methanol, and heating the solution to evaporate the solvent. Any conventionally known method can be employed, such as a method of recovering the copolymer by dispersing the block copolymer solution in water, a method of dispersing the block copolymer solution in water, blowing in water vapor, and distilling off the solvent under heating to recover the copolymer. The block copolymer obtained by the method of the present invention includes a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene having a vinyl aromatic hydrocarbon content of 60 to 95% by weight, which is outside the range specified in the present invention. Resin, block copolymer elastomer of vinyl aromatic hydrocarbon and conjugated diene having a vinyl aromatic hydrocarbon content of less than 60% by weight, polymer of the above vinyl aromatic hydrocarbon monomer, above vinyl aromatic carbonization Copolymers of hydrogen-based monomers 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 , rubber-modified high-impact styrenic resins (HIPS), and the like. 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. In addition, various stabilizers, pigments, antiblocking agents, antistatic agents,
A lubricant etc. can also be added. In addition, anti-blocking agent,
Examples of lubricants and antistatic agents include fatty acid amide, ethylene bisstearamide, sorbitan monostearate, saturated fatty acid esters of aliphatic alcohols, pentaerythol fatty acid esters, and ultraviolet absorbers such as pt-butyl. Phenyl 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 a range of 0.01 to 5% by weight, preferably 0.1 to 2% by weight. The block copolymer obtained by the method of the present invention is transparent and has excellent impact resistance, and can be used as a molding material for various molded products. That is, the block copolymer obtained by the method of the present invention can be processed as it is or after coloring into extrusion molded products such as sheets and films by the same processing means as ordinary thermoplastic resins, and can be processed into extrusion molded products such as vacuum, compressed air, etc. It can be used in a wide range of containers and packaging materials, such as thermoformed molded products, specifically food containers and packaging, blister packaging materials, packaging films for fruits and vegetables, and confectionery. In addition, we also produce toys, daily necessities, food packaging containers, miscellaneous goods made by injection molding and blow molding methods, etc.
It can be used in applications where ordinary general-purpose thermoplastic resins are used, such as in the field of light electrical parts. A particularly preferred application is to print characters or designs on a uniaxially stretched film of the block copolymer specified in the present invention, and then apply heat shrinkage to the surface of a packaged object such as a plastic molded product, metal product, glass container, or porcelain. It can be used as a material for so-called heat-shrinkable labels, which are used in close contact with each other. In particular, the uniaxially oriented heat-shrinkable film obtained from the block copolymer obtained by the method of the present invention has excellent shrinkage characteristics and environmental damage resistance, so it is difficult to heat-shrink plastic molded products that would otherwise deform when heated to high temperatures. In addition to the adhesive label material, materials such as metal, porcelain, glass,
At least one member selected from paper, polyolefin resins such as polyethylene, polypropylene, and polybutene, polymethacrylate ester resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and polyamide resins is used as a constituent material. It can be suitably used as a heat-shrinkable label material for containers. In addition to the above-mentioned resins, polystyrene, rubber-modified impact-resistant materials, etc., which can be used for the heat-shrinkable block copolymer film obtained by the method of the present invention include, in addition to the above-mentioned resins. polystyrene (HIPS),
Styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, acrylonitrile-
Butadiene-styrene copolymer (ABS), methacrylic acid ester-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, polyvinylidene chloride resin, phenol resin, urea resin, melamine resin, epoxy resin, unsaturated Examples include polyester resin and silicone resin. These plastic containers may be a mixture of two or more resins or may be a laminate. [Effects of the Invention] The block copolymer obtained by the method of the present invention has excellent low-temperature stretchability, so that it can be easily stretched and has excellent low-temperature shrinkability, and can be made into a film that exhibits excellent shrinkability in a short time even at high temperatures. Because it has good rigidity, it is especially suitable for use in applications such as labels for various containers, and because it has excellent impact resistance, it is suitable for covering items that are prone to scattering fragments when broken.
Because it has excellent environmental damage resistance, it can withstand being left in the natural environment for long periods of time. Furthermore, the block copolymer obtained by the method of the present invention can be made into various molded products by methods such as injection molding, blow molding, extrusion molding, and inflation molding.
It can be a film or a sheet. In particular, the block copolymer obtained by the method of the present invention has excellent blow moldability, so it can be used for various methods such as extrusion blow method, injection blow method, injection/extrusion blow method, sheet/extrusion blow method, sheet blow method, cold barison method, etc. Various hollow molded products can be obtained by the method. [Examples] The present invention will be explained in more detail by examples below, but it goes without saying that the scope of the present invention is not limited to these examples. Examples 1 to 7 and Comparative Examples 1 to 8 Block copolymers having a polymer structure represented by the general formula ABCBA were produced using n-butyllithium as a catalyst in a cyclohexane solvent. 125 parts by weight of cyclohexane was charged into a stainless steel polymerization vessel equipped with a stirrer and internally replaced with nitrogen gas.
After setting the internal temperature to about 70℃, add n-butyllithium.
A cyclohexane solution containing 0.05 parts by weight of styrene and 23 parts by weight of styrene was continuously supplied using a metering pump over 30 minutes to cause polymerization. Thereafter, the temperature in the polymerization system was maintained at about 70° C. for 10 minutes to substantially completely polymerize the monomer. Next, a cyclohexane solution containing 12.5 parts by weight of styrene and 3 parts by weight of butadiene was continuously supplied using a metering pump over 20 minutes to cause polymerization. Thereafter, the temperature in the polymerization system was maintained at about 70° C. for 10 minutes to substantially completely polymerize the monomer. Next, a cyclohexane solution containing 9 parts by weight of styrene and 14 parts by weight of butadiene was continuously supplied using a metering pump over 30 minutes, and after the supply was finished, the temperature in the polymerization system was maintained at approximately 70°C for 10 minutes to form a monomer. was substantially completely polymerized. Furthermore, a cyclohexane solution containing 12.5 parts by weight of styrene and 3 parts by weight of butadiene was continuously supplied using a metering pump over a period of 20 minutes, and after the supply was finished, the temperature in the polymerization system was maintained at approximately 70°C for 10 minutes to substantially remove the monomer. polymerized. Finally, a cyclohexane solution containing 23 parts by weight of styrene was continuously supplied using a metering pump over 30 minutes, and after the supply was finished, the temperature in the polymerization system was maintained at approximately 70°C for 10 minutes to substantially completely remove the monomer. Polymerized. Thereafter, 2 parts by weight of methanol was added to the polymerization solution to stop the polymerization, and then 0.5 parts by weight each of 2,6-di-tert-butyl-4-methylphenol and trisnonylphenyl phosphorite were added as stabilizers. (The polymer number of the obtained block copolymer is .) By the same method as above and according to the treatment shown in Table 1, the polymer structure is A-B-C-B-A, A-
Block copolymers represented by the general formulas C-B-A and A-C-A-C-A were produced. The amount of catalyst is based on the melt flow index (according to JIS K 6870) of the finally obtained block copolymer.
conditions) was adjusted to approximately 5. (The polymer number of the obtained block copolymer is . The entire amount of each monomer is fed into the polymerization vessel at once, and the polymer structure is changed to A-C-
Block copolymers represented by the general formulas B-A and (A-B-C) ₄ --Si were produced. In addition, the block copolymer is prepared after the polymerization in Step 3 is completed.
1/4 mol of n-butyllithium used
It was produced by adding SiCl ₄ and causing a coupling reaction. (The polymer number of the obtained block copolymer is .
It was formed into a sheet with a thickness of 0.25 mm at 200°C using a φ extruder, and then the block copolymer was stretched 5 times and the block copolymer composition was uniaxially stretched horizontally by 4 times using a tenter. A film with a thickness of about 50μ to 60μ was produced. At this time, the temperature in the tenter was set to the lowest temperature at which a uniaxially stretched film could be stably produced from each block copolymer without causing breakage during stretching. Next, we examined the tensile modulus and puncture strength in the stretching direction of the film of each block copolymer and block copolymer composition at 80°C in the stretching direction.
The heat shrinkage rate was measured. As a result, it was revealed that the film obtained from the block copolymer of the present invention exhibited good stiffness, impact resistance, and shrinkage.
All of these films had a heat shrinkage rate of less than 5% at 80°C in the direction orthogonal to the stretching direction. Moreover, all of them were transparent films. Next, after printing letters and patterns on the film of each block copolymer and block copolymer composition obtained as above, the stretched direction is the circumferential direction, and the unstretched direction is A cylindrical heat-shrinkable label was produced by oriented vertically, placed on a glass bottle using an automatic shrink label machine, and passed through a shrink tunnel controlled at a temperature of approximately 180°C to heat-shrink it. The time taken to pass through the shrink tunnel was controlled so that each heat-shrinkable label was in tight contact with the glass bottle surface, but labels with a lower heat shrinkage rate at 80°C took a longer time. The films of Comparative Examples 5 and 8 had low rigidity, and good coated products could not be obtained. In this way, when the environmental damage resistance of glass bottle coating products made from the block copolymer was investigated, all of the film coating products made from the block copolymer of the present invention showed good performance. had.

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[Table] Examples 8 to 10 Injection molded articles were produced using the block copolymers and, and the physical properties of the obtained molded articles are shown in Table 6.

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[Table] From Example 11 block copolymer and the same block copolymer composition as Examples 3 and 6, sheets with a thickness of 1.2 mm were produced at 200°C using a 40 mmφ extruder, and then vacuum formed. A cylindrical cup with a diameter of 50 mmφ and a height of 40 mm was formed using the equipment. Each cup-shaped molded product obtained was filled with 50 ml of water and allowed to fall naturally onto a concrete surface from a height of 1 m, but the cup did not break. Example 12 The same block copolymer or block copolymer composition used in Examples 1 to 6 was extruded into a molten parison using an extruder at a cylinder temperature of 200°C, and the parison was placed in a split mold. A cylindrical bottle with an average body wall thickness of 0.3 mm and an internal volume of 200 c.c. was molded using this method.
All of these bottles have no surface roughness,
The gloss and transparency were also good. B-1 and B-3 under the same molding conditions for comparison.
When a cylindrical bottle was molded using this block copolymer, the surface had a shark-skin texture, lacked luster, and had poor transparency.

Claims (1)

[Claims] 1. In a hydrocarbon solvent, using an organolithium compound as an initiator, the polymer structure is (a) A-B-C (b) A-B-C-A (c) A-B-C -B-A (d) B-A-C-B-A (e) C-B-A-C-B-A (f) A-C-B-A-C-B-A (g) A -C-B-A-B-C-A (chi) (A-B-C) _o+1 ---X (li) (B-A-C) _o+1 ---X (nu) ( A-B-C-A) _o+1 ---X (ru) (A-B-C-B-A) _o+1 ---X (wo) (B-A-C-B) _{o+ 1} ---X (wa) (B-A-B-C) _o+1 ---X (In the above formula, A means that the weight ratio of vinyl aromatic hydrocarbon and conjugated diene exceeds 90/10, and 100 /0 or less, B is a vinyl aromatic hydrocarbon to conjugated diene weight ratio exceeding 75/25,
Polymer segment in the range of 90/10 or less, C is a vinyl aromatic hydrocarbon to conjugated diene weight ratio of 75/25
Below, polymer segments in the range of 0/100 or more are shown. X represents a residue of a coupling agent or a residue of a polyfunctional organolithium compound. n is an integer from 1 to 5. ) with a number average molecular weight of 30,000~
500,000, in which the overall weight ratio of vinyl aromatic hydrocarbon to conjugated diene is from 60/40 to 95/5, (a) vinyl in the monomer charged for forming each segment; The aromatic hydrocarbon content is within the range of the vinyl aromatic hydrocarbon content corresponding to each of the above polymer segments, and (b) the total monomer amount (A') of the portion corresponding to segment A in all monomers charged is 20 to 80 parts by weight, the total amount of monomers (B') in the part corresponding to segment B is 10 parts by weight or more, the total amount of monomers (C') in the part corresponding to segment C is 10 parts by weight or more, the combination of B' and C' The total amount is 20 to 80 parts by weight (however,
A′+B′+C′=100 parts by weight), (c) Segment B is a mixture of vinyl aromatic hydrocarbon and conjugated diene having the above composition ratio, which is continuously fed into the polymerization system () and polymerized. and/or () based on 100 parts by weight of all monomers charged
A method for producing a block copolymer, which comprises polymerizing in the presence of 0.001 to 10 parts by weight of a polar compound or randomizing agent, and forming the block copolymer adjacent to segment A.