JPS6254137B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ionic crosslinked polymer, and more specifically, to a block copolymer consisting of a vinyl aromatic compound with a specific structure and a conjugated diene compound,
The present invention relates to a thermoplastic elastomer composition prepared by adding a divalent or trivalent metal compound to a modified block copolymer in which molecular units containing dicarboxylic acid groups or derivative groups thereof are bonded. In recent years, various block copolymers consisting of polymer blocks that are thermodynamically rubbery at room temperature (soft segments) and polymer blocks that are glassy or crystalline (hard segments) have been developed without vulcanization. It is attracting attention as a thermoplastic elastomer that has rubber elasticity similar to that of conventional rubber at room temperature and fluidity similar to that of conventional plastics at processing temperatures, to which plastic processing technology can be applied. Among such thermoplastic elastomers, vinyl aromatic compound-conjugated diene compound block copolymers such as styrene-butadiene block copolymers and styrene-isoprene block copolymers have a vinyl aromatic compound content of about 70% by weight or less. , most of the polymers are less than 50% by weight, and have elasticity and feel that are closest to those of conventional vulcanized rubber, so they can be used for various types of rubber, such as footwear and industrial products, for which vulcanized rubber has traditionally been used. It is considered suitable as a material for molded products. The above block copolymers are known to have various structures; A is a polymer block mainly composed of a vinyl aromatic compound, B is a polymer block mainly composed of a conjugated diene compound, and X is a polyfunctional coupling. As the residues of the agent, they are AB, A
-B-A, B-A-B, B-A-B-A, A-B
-X-B-A, (A-B) _-3X , (A-B) _-4X , etc. Among these, A-B-A, (A
It is said that a polymer having the structure -B) _-n On the other hand, for example, the general formula (B
-A) _o , B-(A-B) _o (n is an integer of 1 or more). Products that have a polymer block mainly composed of a conjugated diene compound at the end can be polymerized even in a poor solvent of styrene because the polymer block mainly composed of a conjugated diene compound is polymerized as the first step in its production. Although it has many manufacturing advantages such as the smooth progress of the polymerization initiation reaction using a lithium-based catalyst and is easy to manufacture industrially, its mechanical properties such as tensile strength are lower than that of A-(B-
A) It is inferior to _o and (A-B) _-nX structures. Furthermore, the above-mentioned vinyl aromatic compound-conjugated diene compound block copolymer has the disadvantage that it is inferior in heat resistance, oil resistance, etc. compared to conventional vulcanized rubber. For this reason, in order to improve heat resistance, oil resistance, etc., the above block copolymer is further subjected to sulfur vulcanization or peroxide vulcanization after molding, but such vulcanization causes irreversible crosslinking. This is not desirable because it makes remolding impossible and also reduces the rubber elasticity, which is a characteristic of block copolymers. The present inventors have determined that the above (B-A) _o , B-(A-
B) _o , (B-A-B) _-n At least 1 at the end of X, etc.
With the aim of improving or improving the properties of block copolymers, which have polymer blocks mainly composed of individual conjugated diene compounds, as a result of extensive research, we have found that specific reactive groups have been introduced into block copolymers. By adding a divalent or trivalent metal compound and using such a reactive group as a crosslinking point, the composition contains an ionic crosslinked product that is ionicly crosslinked with divalent or trivalent metal ions. It was discovered that an ionic crosslinked product useful as a molding material with improved properties and chemical properties can be obtained, and the present invention was completed. As a technology related to the present invention, Japanese Patent Application Laid-Open No. 1987-
Maleic anhydride is reacted with a mixture of a block copolymer made of a vinyl aromatic compound and a conjugated diene compound and a rubber developing oil, which is described in No. 56427, and a divalent metal oxide is added thereto, and further adhesive There is a hot-melt adhesive/pressure-sensitive adhesive composition made by mixing a reinforcing resin and a reinforcing resin. In this technique, it has been shown that a maleic anhydride adduct of a block copolymer is crosslinked with a divalent metal oxide, but the above invention does not aim at adhesive or sticky compositions. However, there is no mention of mechanical strength such as tensile strength, which is required. There is no suggestion as to whether it can be used as a material for molding applications. Another related technology is JP-A-55-13720, which describes a block copolymer consisting of a vinyl aromatic compound having the structure (A-B) _-nA or (A-B) _oX and a conjugated diene compound. A maleic anhydride compound is reacted with the coalescence, and a monovalent or divalent metal oxide,
It describes a thermoplastic adhesive resin having a specific melt viscosity to which a hydroxide or an organic acid salt is added. However, in the same specification, examples using divalent metal compounds are only described as specific examples showing their superiority as adhesives, and the composition disclosed in the present invention is also used as a molding material, for example. There is no description of mechanical properties. moreover,
In the specification of the same issue, it is stated that the use of a block copolymer having the structure (A-B) _o and B-(A-B) _o , which is the target block copolymer of the present invention, is effective for adhesion at high temperatures. There is a description that it is undesirable due to its poor quality. Further, these known techniques do not mention anything about the ratio of the metal compound to the carboxylic acid anhydride group, etc. Under such circumstances, the present inventors
-A) _o , B-(A-B) _o , {(B-A) _p } _n Vinyl aromatic where at least one of the terminal polymer blocks such as X is a polymer block mainly composed of a conjugated diene compound Even when a block copolymer consisting of a compound and a conjugated diene compound, especially a block copolymer with a B-A-B-A structure, is added with maleic anhydride etc., divalent or trivalent By using a metal compound and adjusting the ionic crosslinking caused by the metal ions to achieve a limited melt index range, it is possible to create a molding material with excellent mechanical properties and oil resistance while maintaining processability. It has been found that suitable thermoplastic elastomer compositions are obtained. Furthermore, as described later in the present invention, an unsaturated dicarboxylic acid such as maleic anhydride was added by a specific method. By using modified block copolymers, it is possible to obtain even more excellent compositions. The present invention is characterized in that: 1 the content of vinyl aromatic compounds is 5 to 70% by weight;
A block copolymer consisting of a vinyl aromatic compound and a conjugated diene compound, wherein at least one of the terminal polymer blocks is a polymer block mainly composed of a conjugated diene compound,
and the following general formula (B-A) _o , B-(A-B) _o , {(B-A) _p }- _n X, {B-(A-B) _p }- _n X (however, A is a polymer block mainly composed of a vinyl aromatic compound, B is a polymer block mainly composed of a conjugated diene compound, X is a residue of a coupling agent having two or more functional groups, n is an integer of 1 or more, m is an integer of 2 or more, and p is an integer of 1 or more.
In a composition formed by adding one or more selected from divalent or trivalent metal compounds to a modified block copolymer bound to 20 parts by weight, (1) the modified block copolymer contains: The molar ratio of metal atoms of the divalent or trivalent metal compound per dicarboxylic acid group or its derivative group is
0.1 to 3.0 (2) Melt index ([M·I] of the obtained composition relative to melt index ([M·I] ₁ ) of the modified block copolymer
₂ ) Ratio [M・I] ₂ / [M・I] ₁ is 0.01
Thermoplastic elastomer composition 2 having a molecular weight of 0.3 to 0.3 The modified block copolymer binds to divalent or trivalent ions of the metal by using a part or all of the dicarboxylic acid groups or derivative groups thereof as crosslinking sites. The composition according to item 1 above, which contains an ionic crosslinked product. 3. The composition according to item 1, wherein the modified block copolymer is one in which molecular units containing 0.05 to 5 parts by weight of dicarboxylic acid groups or derivative groups thereof are bonded to each 100 parts by weight of the block copolymer. . 4. The composition according to item 1 above, wherein the modified block copolymer has 0.1 to 2 parts by weight of molecular units containing a dicarboxylic acid group or a derivative group thereof bonded to each 100 parts by weight of the block copolymer. thing. 5. The composition according to any one of items 1 to 4 above, wherein the dicarboxylic acid derivative group is a dicarboxylic acid anhydride group. 6. The composition according to item 1 above, wherein the divalent or trivalent metal compound is an oxide, hydroxide, carboxylate, or alcoholate of the metal. 7. The composition according to item 1 above, wherein the divalent metal compound is a magnesium compound. 8. The composition according to item 7, wherein the magnesium compound is magnesium oxide or magnesium hydroxide. 9. The composition according to item 2 above, wherein the block copolymer is represented by the general formula B-A-B-A. 10 The modified block copolymer obtained by adding an unsaturated dicarboxylic acid or a derivative thereof to the block copolymer under melt-mixing conditions in which the modified block copolymer does not substantially generate radicals. Composition. 11. The composition according to item 10, wherein the unsaturated dicarboxylic acid derivative is maleic anhydride. 12 The toluene insoluble content of the modified block copolymer is 1
11. The composition according to item 10 above, wherein the composition is not more than % by weight. I will provide a. The present invention will be described in detail below. First, a block copolymer (hereinafter referred to as block copolymer) consisting of a vinyl aromatic compound having a specific structure and a conjugated diene compound, which is the base of a modified block copolymer as a precursor of an ionic crosslinked product, will be described. The block copolymer having the structure used in the present invention has a vinyl aromatic compound content in the range of 5 to 70% by weight, and as described above, at least one of the terminal polymer blocks is mainly composed of a conjugated diene compound. It is a polymer block. The structure of such a block copolymer is represented by the following general formula. (B-A) _o , B-(A-B) _o {(B-A) _p }- _n X, {B-(A-B) _p −} _n X (However, A is a vinyl aromatic compound B is a polymer block mainly composed of a conjugated diene compound, X is a residue of a coupling agent having two or more functional groups, n is an integer of 1 or more,
(m represents an integer of 2 or more, p represents an integer of 1 or more) If the vinyl aromatic compound content of the above block copolymer is less than 5% by weight, the tensile strength etc. will be poor, and if it exceeds 70% by weight. has poor rubber elasticity and is unsuitable as a thermoplastic elastomer. Also,
Molecular structures other than those described above are outside the scope of the present invention. Other structures, e.g. A-(B-A) _o , A-B-)
In the _present invention, for a block copolymer having a block of A at each end of n The block copolymers used, which have B blocks at their ends, lack tensile strength, etc., and improvements in these properties are required. In particular, among these, B-A, B-A-B-
A, (B-A-) ₄ X, (B-A-B-) ₄ X, etc. are preferably used in the present invention. In the above block copolymer, the weight ratio of block A and block B is preferably A/B.
It ranges from 10/90 to 70/30. Block A of the block copolymer is a hard segment of the block copolymer, and its glass transition point is 40°C or higher, preferably 60°C or higher,
The weight ratio of the vinyl aromatic compound and the conjugated diene compound in this block is 100/0 to 60/40,
Preferably 100/0 to 80/20, more preferably
It is 100/0. On the other hand, block B is a soft segment of a block copolymer, and its glass transition point is below 0°C, preferably below -20°C, and the weight ratio of the vinyl aromatic compound and the conjugated diene compound in this block is ,0/100~40/
60, preferably in the range of 0/100 to 30/70.
In each polymer block, the distribution of minor monomer units in the molecular chain can be random, tapered (increasing or decreasing monomer components along the molecular chain), partially block-like, or a combination of these. Good too. The block copolymer has a number average molecular weight of 10,000.
-1000000, preferably 20000-500000, more preferably 30000-300000, and the molecular weight distribution (ratio of weight average molecular weight to number average molecular weight) is 1.01
-10, preferably 1.01-5. The number average molecular weight of each block is preferably 2000~
500,000, more preferably in the range of 5,000 to 200,000. When the block copolymer contains two or more A or B, each block may have the same structure or different structures. The molecular structure of the block copolymer may be linear, branched, radial, or a combination thereof within the limitations of the structure described above. The vinyl aromatic compounds constituting the block copolymer include, for example, styrene, α-methylstyrene,
Vinyltoluene and the like are selected, among which styrene is particularly preferred. On the other hand, the conjugated diene compound is selected from, for example, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc. Among them, butadiene or a combination of conjugated diene compounds mainly containing butadiene is preferred. When butadiene is used as the conjugated diene compound, its microstructure preferably has a 1,2-vinyl content in the range of 7 to 50% by weight. The various limitations described above are necessary for the ionic crosslinked product of the present invention to have the desired properties. The block copolymer can be obtained by polymerizing an organic lithium compound such as butyllithium as a polymerization catalyst in an inert hydrocarbon solvent such as hexane or toluene, and furthermore, the block copolymer can be obtained by polymerizing an organic lithium compound such as butyllithium as a polymerization catalyst in an inert hydrocarbon solvent such as hexane or toluene. A branched or radial block copolymer can be obtained by reacting a block copolymer having terminals with a polyfunctional coupling agent such as silicon tetrachloride, divinylbenzene, etc. In addition, any block copolymer obtained by any production method can be used as the modified block copolymer of the present invention as long as it falls within the range of the above limitations. The above block copolymers can be used alone or in combination of two or more. Next, the modified block copolymer containing a dicarboxylic acid group or its derivative group, which is a precursor of the ionic crosslinked product of the present invention, is a conjugated diene of a block copolymer consisting of a vinyl aromatic compound and a conjugated diene compound. It is a polymer in which a molecular unit containing a dicarboxylic acid group or its derivative group is bonded to a moiety. In such a modified block copolymer, on average, one or more molecular units containing a dicarboxylic acid group or its derivative group are bonded to each molecule of the base block copolymer, and
0.05 to 20 parts by weight per 100 parts by weight, preferably 0.05
It is necessary to add up to 5 parts by weight, more preferably 0.1 to 2 parts by weight, in order to obtain a useful ionic crosslinked product. If the amount is less than the above limit, the improvement effect will be insufficient; if it exceeds 20 parts by weight, there will be almost no improvement in anything less than that; if it exceeds 5 parts by weight, processability may become a problem; if it exceeds 2 parts by weight, In some cases, it may absorb moisture from the air and cause undesirable phenomena such as foaming during molding. Examples of the above dicarboxylic acid derivative groups include dicarboxylic anhydride groups, dicarboxylic monoester groups, and dicarboxylic diester groups. The modified block copolymer used in the present invention is
An unsaturated dicarboxylic acid or a derivative thereof, which is a molecular unit containing a dicarboxylic acid group or a derivative group thereof, is added to a block copolymer consisting of a vinyl aromatic compound and a conjugated diene compound, which is a base, in a molten state or a solution state, It can be obtained by a method of carrying out an addition reaction with or without a radical initiator. There are various more specific production methods for obtaining these modified block copolymers, and any method may be used, but undesirable components such as gel may be present in the resulting polymer. Production methods that contain or reduce the fluidity of the obtained polymer and significantly deteriorate processability should be avoided. Most preferred is a method in which the addition reaction is carried out under melt-mixing conditions. Such a reaction is
As described in the specification of Japanese Patent Application No. 53-99102 (filed on August 16, 1973) previously filed by the applicant, a radical initiator such as a peroxide or an azo compound is added to the reaction system. In order to suppress the free radicals generated during the reaction under heating or high shear, one or more types of known radical inhibitors, such as phenol type, phosphorus type, and amine type, are used in combination, preferably two or more types. This can be achieved by adding Such a reaction is
It can be suitably carried out in an apparatus normally used for mixing polymers, such as an extruder or a mixer. According to the above method, it is simpler than the conventional method, which requires steps such as performing the reaction in a solution and recovering the reaction product, and furthermore, it is possible to use a peroxide or an azo radical initiator. Compared to this method, a good modified block copolymer with less decrease in melt index and containing almost no gel can be obtained, and the modified block copolymer obtained by this method is a precursor of the ionic crosslinked product of the present invention. Most suitable as a substance. The above-mentioned preferred modified block copolymer has a gel amount expressed by toluene-insoluble portion of 1% by weight or less, preferably 0.5% by weight or less. Examples of the unsaturated dicarboxylic acids or derivatives thereof include maleic acid, fumaric acid, chloromaleic acid, itaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid, endo-cis-bicyclo[2,2,1] Examples include dicarboxylic acids such as -5-heptene-2,3-dicarboxylic acid and their anhydrides, monoesters, diesters, and other derivatives, and among these, maleic acid, fumaric acid, and maleic anhydride are particularly preferred. It should be noted that the fact that the modified block copolymer was obtained by the above-mentioned reaction method means that, for example, an infrared spectrophotometer or an acid-
It can be confirmed by base titration. Next, the thermoplastic elastomer composition of the present invention will be described. As mentioned above, in the composition of the present invention, the molecular unit containing a dicarboxylic acid group or a derivative group thereof as a precursor thereof is a block compound consisting of a vinyl aromatic compound having the specific structure as a base and a conjugated diene compound. One selected from divalent or trivalent metal compounds is added to the modified block copolymer bonded to the polymer.
The thermoplastic elastomer composition is a thermoplastic elastomer composition in which one or more species are added, and the composition preferably uses the dicarboxylic acid group or its derivative group contained in the modified block copolymer as the crosslinking site, and It contains an ionic crosslinked product of the above-mentioned polymer which is ionicly crosslinked with trivalent ions. The above-mentioned divalent or trivalent ions of metals are divalent or trivalent ions of metals of groups, groups, groups, groups of the periodic table, and specifically,
Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Ba ²⁺ , Zn ²⁺ , Sn ²⁺ , Hg ²⁺ ,
Examples include metal ions such as Ag ²⁺ , ^{Cu 2+} , Al ³⁺ , Ti ³⁺ , Fe 2+ , and Fe ³⁺ . The metal compound is a compound containing these divalent or trivalent metals. In order to obtain the composition of the present invention, any of the above-mentioned metal compounds can be used, but oxides, hydroxides, and carboxylates of these metals may be used, especially considering the efficiency of the ionic crosslinking reaction. , alcoholates, and organometallic compounds (dialkylmagnesium, trialkylaluminum, etc.) are preferably used. When using divalent or trivalent metal compounds,
The ionic crosslinking reaction progresses relatively slowly, and by appropriately adjusting the mixing conditions with the modified block copolymer and the molding conditions, a composition with good properties as described below can be obtained after a certain period of time after molding. can do. In such cases, the metal compound may remain unreacted. The ionic crosslinked product is formed by ionizing a part or the entire amount of the dicarboxylic acid group or its derivative group to become a carboxy anion, and forming an ionic bond with a divalent or trivalent metal ion as a counter cation. and its ionization rate,
That is, the crosslinking rate can be easily adjusted by adjusting the amount and type of metal compound added. The ionization crosslinking reaction described above may require an excess of the stoichiometric amount of the metal compound. This ionization rate, that is, the crosslinking rate, can be easily measured using, for example, an infrared spectrophotometer. In order to effectively obtain the composition of the present invention, depending on the desired degree of crosslinking, the divalent or trivalent metal compound per dicarboxylic acid group or its derivative group contained in the modified block copolymer must be The molar ratio of atoms (bivalent or trivalent metal/dicarboxylic acid group or derivative group thereof) is in the range of 0.1 to 3.0. If the above molar ratio is less than 0.1, the improvement in oil resistance and mechanical properties is slight, and even if it exceeds 3.0,
The improvement effect below this level is slight. In addition, in order for the composition of the present invention to have improved mechanical properties and oil resistance compared to unmodified block copolymers and modified block copolymers while maintaining processability, Melt index of composition (JIS-K-6870, load 5Kg,
200℃) can be used as an indicator. In order to achieve the above-mentioned improvement effect, the melt index ([M·I] is assumed to be ₁ ) of the modified block copolymer as a precursor. The ratio [M·I] ₂ /[M·I] ₁ to the melt index of the composition ([M·I] is assumed to be ₂ ) must be in the range of 0.01 to 0.3, more preferably 0.02 to 0.2. It is. When the above amount exceeds 0.3, the improvement effect is slightly inferior to that below, and conversely, when it is less than 0.01, problems occur in workability. Also, the melt index value is 1.0g/
In cases where the temperature is lower than 10 min, the melt
In order to more accurately measure changes in the index, the melt index of the precursor can be determined by adding 10 to 100 parts by weight, preferably 20 to 50 parts by weight of a softening agent, such as a naphthenic process oil, per 100 parts by weight of the composition. 2-20g/10min, preferably 5-15
It can be said that a preferable method is to adjust the temperature to a range that allows accurate measurement of g/10 min, more preferably from 9 to 11 g/10 min, and to understand the change in the melt index. Furthermore, in the composition containing the ionic crosslinked product of the present invention, the amount of dicarboxylic acid groups not involved in ionic crosslinking is 1.0 parts by weight or less, preferably 1.0 parts by weight or less, per 100 parts by weight of the block copolymer.
It can be said that it is preferable that the amount is 0.5 part by weight or less in terms of water resistance of the ionic crosslinked product. The composition of the present invention can be obtained, for example, by adding a metal compound to a molten modified block copolymer, or by dissolving the modified block copolymer in a suitable solvent and adding a metal compound or its solution to this solution. There is a method of adding a metal compound to cause a crosslinking reaction, and a method of using a modified block copolymer as a latex and adding a metal compound to it. Either of these methods can be used to obtain the composition of the present invention. be able to. The above reaction can be carried out not only in reaction apparatuses commonly used for various reactions such as autoclave-type and flask-type reaction apparatuses, but also inside mixing machines such as extruders, mixing rolls, and various mixers. Furthermore, if heating is required, it is also possible to perform molding and heating using a press or the like. The composition of the present invention is thermoplastic and can be molded, unlike conventional covalently crosslinked products such as sulfur crosslinks and peroxide crosslinks, and also contains uncrosslinked vinyl aromatic compound-conjugated products. Compared to diene compound block copolymers, it has improved oil resistance and heat resistance, and also has excellent mechanical properties. The composition of the present invention may contain inorganic fillers such as carbon black and glass fiber, reinforcing agents, colorants, antioxidants, ultraviolet inhibitors, lubricants, and the like. Moreover, the ionic crosslinked product of the present invention is
New composite materials can be created by creating compositions with various thermoplastic polymers such as polyolefin polymers and polystyrene polymers, their low molecular weight products, unvulcanized rubber, and precursors of various thermosetting polymers. It is also possible to do so. Examples of such thermoplastic polymers include low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, polybutene, 1,
Ionic crosslinked products (ionomers) of 2-polybutadiene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, Polyolefin polymers such as ethylene-vinyl alcohol copolymer, chlorinated polyethylene, chlorosulfonated polyethylene, general-purpose polystyrene, high-impact polystyrene, acrylonitrile-styrene copolymer,
ABS resin, styrene-maleic anhydride copolymer, styrene-methyl methacrylate copolymer,
Styrenic polymers such as MBS resin, polyacrylate polymers, polyvinyl chloride polymers (including soft ones), polyvinylidene chloride polymers,
Polyamide polymers such as nylon-6 and nylon-66, thermoplastic polyester polymers such as polyethylene terephthalate and polybutylene terephthalate, polyphenylene sulfide polymers, polyphenylene ether polymers, polycarbonate polymers , polysulfone-based polymers, polyacetal-based polymers, thermoplastic polyurethane-based polymers, and the like. Examples of unvulcanized rubber include polybutadiene rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, ethylene-propylene-diene copolymer rubber, acrylic rubber, silicone rubber, fluorine rubber, and polyurethane rubber. Can be mentioned. In addition, precursors of thermosetting resins include phenolic resins, amino resins, alkyd resins, epoxy resins, urea resins, thermosetting polyurethanes,
Precursors such as xylene resin and ketone resin may be mentioned. By mixing the composition of the present invention and these precursors and then curing it, a thermosetting polymer composition containing an elastomer component can be obtained. The composition of the present invention can be used in a wide variety of applications, for example, as a molding material alone or in the various compositions described above. Rubber-like objects can be used in similar ways to conventional rubber, such as footwear, belts, hoses, tubes, industrial goods, toys, daily necessities, sponges, packing, electrical parts, and automobile parts. In addition, resin-like products can be used as films, sheets, or molded products, such as packaging materials, automobile parts, electrical appliance parts,
Applications include industrial parts, daily necessities, and toys. The above-mentioned various products can be molded by a molding method such as compression molding, extrusion molding, or injection molding, or can be used after being processed into a foam or the like. The present invention will be described in more detail below with reference to Examples, but it goes without saying that the scope of the present invention is not limited to these Examples. Example 1 [Production of modified block copolymer] A modified block copolymer having a dicarboxylic anhydride group was obtained by reacting the styrene-butadiene block copolymer shown below with maleic anhydride. The styrene-butadiene block copolymer (sample a) used was n-
This is a polymer obtained by polymerizing butyllithium as a polymerization catalyst, and it is thought to have the following structure based on the polymerization method and various analysis results.・Polymer structure: B ₁ −S ₁ −B ₂ −S ₂ (linear) B ₁ = 18% by weight [B] / [S] = 16/2
(Tapered) S ₁ = 17% by weight [B] / [S] = 0/17 B ₂ = 49% by weight [B] / [S] = 46/3
(Tapered) S ₂ = 16% by weight [B] / [S] = 0/16, where B _o represents a polymer block mainly composed of butadiene, and S _o represents a polymer block mainly composed of styrene, and is an integer. n represents the order along the molecular chain. [B] is the butadiene content (% by weight based on the entire block copolymer), [S]
indicates the styrene content (% by weight based on the entire block copolymer) (hereinafter, the same notation will be used).・Styrene content: 38% by weight ・Block styrene content: 33% by weight ・Weight average molecular weight (Mw): 81000 ・Number average molecular weight (Mn): 62000 ・Melt index: 11.0g/10min (JIS
-K-6870, load 5Kg, 200℃) For 100 parts by weight of the above sample a, 1.5 parts by weight of maleic anhydride and 0.5 parts by weight as an anti-gelling agent.
BHT (butyl hydroxytoluene) and 0.1 part by weight of phenothiazine were added, and these were mixed uniformly using a mixer. This mixture was supplied to a 40 mm extruder (single screw, full-flight screw, L/D=24) under a nitrogen atmosphere, and a modification reaction was carried out at a cylinder temperature of 195 to 205°C. Unreacted maleic anhydride was removed by drying the obtained polymer under reduced pressure. This modified block copolymer (sample A) had a melt index [M・I] _{of 18.2} g/10 min, a toluene insoluble content of 0.02% by weight, and an added amount of maleic anhydride measured by titration with sodium methylate. , 0.60 parts by weight per 100 parts by weight of the block copolymer, and the toluene insoluble content was 0.03% by weight. In addition, three types of block copolymers (samples b, c, and d) with various structures shown in Table 1 were added with maleic anhydride using the same extruder used to obtain sample A. Modified block copolymers (samples B, C, and D) were obtained. These analytical values are shown in Table 1. Examples 2, 3, 4, 5, Comparative Examples 2, 3, 4, 5 A metal compound was added to modified block copolymer samples A, B, C, and D under the conditions shown in Table 2 to form a composition of the present invention. I got it. Table 3 shows the physical properties of compression molded products of these compositions.
It is shown in Table 4. As shown in Tables 3 and 4, Examples 2-1 to 2-
4, 3, 4, and 5 have improved mechanical strength, oil resistance, and heat resistance compared to the corresponding unmodified block copolymers and modified block copolymers, respectively, and the compositions of the present invention can be molded. This shows its usefulness as a material.

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Claims (1)

[Claims] 1. Content of vinyl aromatic compound is 5 to 70% by weight
A block copolymer consisting of a vinyl aromatic compound and a conjugated diene compound, in which at least one of the terminal polymer blocks is a polymer block mainly composed of a conjugated diene compound, and has the following general formula ( B-A) _o , B-(A-B) _o , {(B-A) _p }- _n X, {B-(A-B) _p }- _n X (However, A is a vinyl aromatic compound B is a polymer block mainly composed of a conjugated diene compound, X is a residue of a coupling agent having two or more functional groups, n is an integer of 1 or more,
(m is an integer of 2 or more, p is an integer of 1 or more) 0.05 to 20 molecular units containing a dicarboxylic acid group or its derivative group are added per 100 parts by weight of the block copolymer. A modified block copolymer formed by combining parts by weight of 2
In a composition comprising one or more selected from valent or trivalent metal compounds, (1) a divalent or trivalent metal compound per dicarboxylic acid group or its derivative group contained in the modified block copolymer;
The molar ratio of metal atoms in the valent metal compound is 0.1 to 3.0 (2) The melt _index ([M・I] ] ₂ ) A thermoplastic elastomer composition in which the ratio [M·I] ₂ /[M·I] ₁ is 0.01 to 0.3.