JPWO2008114741A1 - Thermoplastic elastomer composition and elastomer molded body - Google Patents

Abstract

A thermoplastic elastomer composition comprising 30 to 85% by weight of a styrenic block copolymer (A) and 70 to 15% by weight of an olefin-acrylic acid alkyl ester copolymer (B). Preferably, the olefin-acrylic acid alkyl ester copolymer (B) is preferably 30 to 90% by weight of olefin monomer units, 10 to 70% by weight of acrylic acid alkyl ester monomer units, and maleic anhydride monomer. It is a copolymer composed of 0 to 10% by weight of a monomer unit, and the styrenic block copolymer (A) is preferably a styrene-isoprene block copolymer. The thermoplastic elastomer composition provides an elastomer molded body having an excellent balance of flexibility, vibration damping properties and adhesiveness.

Description

The present invention relates to a thermoplastic elastomer composition and an elastomer molded body, and more particularly to a thermoplastic elastomer composition that provides an elastomer molded body having an excellent balance of flexibility, vibration damping property, and adhesiveness.

In living spaces and vehicles, it is required to be comfortable from being freed from noise, vibration and shock. For this purpose, it is necessary to take measures to absorb noise, vibration or impact at the interface or gap surface between components constituting the equipment, device or material that is the source of noise, vibration or impact.
In order to satisfy this requirement, a vibration damping material (Patent Document 1) containing petroleum resin and butyl rubber and an anti-vibration rubber body (Patent Document 2) in which a highly damped silicon gel molded body is enclosed in vulcanized rubber have been proposed. . However, in these proposals, the adhesiveness between the damping material and the base material and the damping property such as vibration are insufficient.

Attempts have also been made to develop excellent elastomeric materials that can be absorbed or inserted into interfaces or gaps between components constituting equipment, devices, materials, etc. to effectively absorb vibrations and shocks.
For such an elastomer material, Patent Document 3 proposes a resin composition comprising a styrene block copolymer thermoplastic elastomer, a maleic anhydride grafted polyolefin, and a paraffinic oil. However, the thermoplastic elastomer material obtained from this resin composition is insufficient in flexibility, and furthermore, the vibration damping property and the adhesion to the adherend are still insufficient.

In Patent Document 4, a flexible viscoelastic material (b) is provided between a plurality of metal plates (b) provided between two members constituting the structure, which are relatively displaced when the structure vibrates. Disclosed is a damper having an inserted structure, in which (a) and (b) are bonded together with a multilayer adhesive tape having two adhesive surfaces made of different compositions. . However, although this damper exhibits adhesiveness based on adhesion to a metal plate, the adhesive force is still not sufficient, and there is a problem that a large number of steps are required to produce the structure.
Therefore, an elastomer material that is excellent in the balance between flexibility, vibration damping property, and adhesiveness is desired.

JP 09-136998 JP 05-149376 JP 2001-192527 A JP 2006-258156 A

  In view of the above circumstances, an object of the present invention is to provide a thermoplastic elastomer composition that provides an elastomer molded article having an excellent balance of flexibility, vibration damping properties, and adhesiveness.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by using a specific block copolymer and a specific olefin copolymer at a specific ratio. The present invention has been completed based on the findings.

  Thus, according to the present invention, a thermoplastic elastomer composition comprising 30 to 85% by weight of a styrenic block copolymer (A) and 70 to 15% by weight of an olefin-alkyl acrylate copolymer (B). Things are provided.

Preferably, the olefin-alkyl acrylate copolymer (B) is composed of 30 to 90% by weight of olefin monomer units, 10 to 70% by weight of alkyl acrylate monomer units and maleic anhydride monomer units. It consists of 0 to 10% by weight.
More preferably, the olefin-alkyl acrylate copolymer (B) is composed of 40 to 87% by weight of olefin monomer units, 12 to 52% by weight of alkyl acrylate monomer units, and maleic anhydride monomer. It is an olefin-acrylic acid alkyl ester-maleic anhydride copolymer containing 1 to 8% by weight of units.

  Preferably, the styrenic block copolymer (A) is a styrene-isoprene block copolymer containing 5 to 40% by weight of a styrene monomer unit, and the styrene-isoprene block copolymer. 30 to 95% by weight, and the vinyl bond content in all isoprene units is 30% by weight or less.

  Moreover, according to another this invention, the elastomer molded object formed by shape | molding the thermoplastic elastomer composition of any one of said aspects is provided.

The thermoplastic elastomer composition of the present invention provides an elastomeric form with an excellent balance of flexibility, vibration damping and adhesion.

  The thermoplastic elastomer composition of the present invention comprises 30 to 85% by weight of a styrenic block copolymer (A) and 70 to 15% by weight of an olefin-acrylic acid alkyl ester copolymer (B).

In the thermoplastic elastomer composition of the present invention, the styrenic block copolymer (A) (hereinafter sometimes referred to as “component (A)”) is preferably a styrene monomer unit as a main constituent unit. At least one polystyrene block containing, and at least one conjugated diene polymer block containing a conjugated diene monomer unit as a main constituent unit and / or at least one monofin containing a monoolefin monomer unit as a main constituent unit It is a block copolymer comprising polymer blocks.
Here, “containing as a main constituent unit” means containing at least 50% by weight of each monomer unit.

  As the styrenic block copolymer (A), those containing 5 to 40% by weight, more preferably 7 to 35% by weight, and particularly preferably 10 to 30% by weight of a styrene monomer unit are suitable. . If the styrene monomer unit content is low, the shape retention as an elastomer molded product may be reduced. On the other hand, if the amount is too large, the flexibility may be lowered, and further, the fluidity of the thermoplastic elastomer composition may be deteriorated and the moldability may be deteriorated.

  Examples of the styrenic block copolymer (A) include a styrene-isoprene block copolymer and a hydrogenated product thereof, a styrene-butadiene copolymer and a hydrogenated product thereof, and a styrene-isobutylene block copolymer. Of these, a styrene-isoprene block copolymer is preferable because it is easy to obtain an elastomer molded body excellent in vibration damping properties and flexibility. These may be used alone or in combination of two or more.

The styrene-isoprene block copolymer is composed of at least one polystyrene block containing a styrene monomer unit as a main constituent unit and at least one polyisoprene block containing an isoprene monomer unit as a main constituent unit. It is a block copolymer. Specific examples thereof include styrene-isoprene diblock copolymer (SI), styrene-isoprene-styrene triblock copolymer [(SIS), (SI) ₂ X, X is a coupling agent residue], styrene- Isoprene 3-branched block copolymer [(SI) ₃ X, X is a coupling agent residue], Styrene-isoprene 4-branched block copolymer [(SI) ₄ X, X is a coupling agent residue And mixtures thereof.

  Among these, those having a styrene-isoprene diblock copolymer (SI) of preferably 30 to 95% by weight, more preferably 40 to 90% by weight, and particularly preferably 45 to 85% by weight are more excellent vibration damping. This is suitable because it gives an elastomer molded body having the properties.

  The weight average molecular weight of the styrene-isoprene diblock copolymer is preferably 50,000 to 250,000, more preferably 60,000 to 230,000, and particularly preferably 70,000 to 200,000. Further, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 2 or less, and more preferably 1.5 or less. If the weight average molecular weight is low, the shape retainability as an elastomer molded product may be lowered. On the other hand, if it is too large, the fluidity of the thermoplastic elastomer composition may deteriorate and the moldability may deteriorate.

  The remaining components other than the styrene-isoprene block copolymer (SI) in the styrene-isoprene block copolymer are not particularly limited as long as they are styrene-isoprene block copolymers other than SI, but styrene-isoprene-styrene. Triblock copolymers are preferred from the viewpoint of flexibility.

  The polystyrene block in the styrene-isoprene block copolymer refers to a portion having a styrene monomer unit as a main constituent unit. The polystyrene block preferably has a styrene monomer unit content of 80% by weight or more, and more preferably a homopolymerized styrene. If the styrene monomer unit content is low, the shape retainability may be inferior.

  The polystyrene block may be a copolymer of styrene and a monomer copolymerizable with styrene as long as the effect of the present invention is not substantially inhibited. Preferred examples of the monomer copolymerizable with styrene include conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene.

  The weight average molecular weight of the polystyrene block in the styrene-isoprene block copolymer is preferably 8,000 to 100,000, more preferably 12,000 to 80,000, and particularly preferably 14,000 to 50,000. When the weight average molecular weight of the polystyrene block is too small, there is a possibility that the shape retention as an elastomer molded product is lowered. On the other hand, if it is too large, the fluidity of the thermoplastic elastomer composition may deteriorate and the moldability may deteriorate.

  The polyisoprene block in the styrene-isoprene block copolymer refers to a portion having an isoprene monomer unit as a main constituent unit. The polyisoprene block preferably contains 80% by weight or more of isoprene monomer units, and more preferably isoprene homopolymerized. When there is too little content of an isoprene monomer unit, there exists a possibility that the softness | flexibility of the molded object obtained may be inferior.

  The polyisoprene block may be a copolymer of isoprene and a monomer copolymerizable with isoprene as long as the effects of the present invention are not substantially inhibited. Monomers copolymerizable with isoprene include aromatic vinyl monomers such as styrene, α-methylstyrene, methylstyrene; 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1, A conjugated diene monomer other than isoprene such as 3-pentadiene is preferably used.

  In addition, the vinyl bond content in all isoprene units in the styrene-isoprene block copolymer is preferably 30% by weight or less, more preferably 15% by weight or less, and particularly preferably 5 to 10% by weight. If the vinyl bond content is high, flexibility may be inferior.

  The weight average molecular weight of the styrenic block copolymer (A) is preferably 50,000 to 1,000,000, more preferably 60,000 to 860,000, and particularly preferably 70,000 to 800,000. .

  The manufacturing method of a styrene-type block copolymer (A) is not specifically limited, Generally a well-known manufacturing method is employable. Below, it describes about the example which manufactures a styrene-isoprene block copolymer.

  By the anion living polymerization method, after forming the polystyrene block, a polyisoprene block is formed at its end to obtain a diblock copolymer, and in some cases, a sequential polymerization method is employed in which a polystyrene block is further formed at the end. Further, a method of producing a coupled block copolymer by forming a polyisoprene block at the terminal after forming a polystyrene block by an anion living polymerization method and reacting it with a coupling agent can be employed.

In the case of the sequential polymerization method, the content of the styrene-isoprene diblock is partially removed at the stage of the styrene-isoprene diblock, and styrene is added to the remainder to continue the polymerization to obtain a styrene-isoprene triblock, which is taken out in the middle. It can be adjusted by a method such as returning the styrene-isoprene diblock.
When using a coupling agent, methods such as adjusting the amount of diblock by adjusting the type and amount of coupling agent can be employed. Moreover, even if diblock bodies, triblock bodies, and mixtures of diblocks and triblocks having different contents are mixed, adjustment is possible, and various methods can be adopted. In that case, the content of the styrene-isoprene diblock may be kneaded simultaneously with the olefin-alkyl acrylate copolymer (B) described later.
The molecular weight, molecular weight distribution, and vinyl bond amount can be adjusted by using known methods.

In the present invention, an olefin-alkyl acrylate copolymer (B) [may be referred to as “B component”. ] Is not limited as long as it is a copolymer of monoolefin and / or diolefin and alkyl acrylate.
The carbon number of the monoolefin is preferably 2 to 10, more preferably 2 to 6, particularly preferably 2 to 4, and the carbon number of the diolefin is preferably 4 to 10, more preferably 4 to 8, and particularly preferably 4. ~ 6. If the carbon number is too large, the adhesiveness may decrease. Specific examples include monoolefins such as ethylene, propylene, n-butene, isopentene, and 2-octene; 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and the like. Of diolefins. Of these, ethylene or propylene is preferable, and ethylene is more preferable in terms of superior flexibility.

  Carbon number of the alkyl group in the acrylic acid alkyl ester is preferably 1-8, more preferably 1-6, and particularly preferably 1-4. If the carbon number is too large, the adhesiveness may decrease. Specific examples thereof include alkyl acrylate esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. Of these, methyl acrylate or ethyl acrylate is preferred because of its superior flexibility.

  The olefin-acrylic acid alkyl ester copolymer (B) comprises a monomer unit of monoolefin or diolefin, a monomer unit of acrylic acid alkyl ester, and a monomer copolymerizable with these monomers. You may have a unit of a mer. Examples of the copolymerizable monomer include butenedionic acid such as maleic acid and fumaric acid, and polyvalent carboxylic acid anhydride such as maleic anhydride and phthalic anhydride, and maleic anhydride is preferable.

  Suitable olefin-acrylic acid alkyl ester copolymer (B) is preferably 30 to 90% by weight of olefin monomer units, more preferably 40 to 87% by weight, particularly preferably 50 to 83% by weight; acrylic acid. Preferably 10 to 70% by weight of alkyl ester monomer units, more preferably 12 to 52% by weight, particularly preferably 15 to 43% by weight; and; preferably 0 to 10% by weight of maleic anhydride monomer units. More preferably, it is a copolymer having 1 to 8% by weight, particularly preferably 2 to 7% by weight.

  When there are too many olefin monomer units, there is a possibility that the flexibility is lowered, and when there are too few, there is a possibility that the adhesive force is lowered. On the other hand, if the amount of the acrylic acid alkyl ester monomer unit is too large, the adhesive force may be reduced, and if the amount is too small, the flexibility may be deteriorated. Although it is preferable to contain a maleic anhydride monomer unit at the point which can improve adhesiveness, when too much, there exists a possibility that a softness | flexibility may fall.

  The MFR (melt viscosity, a value measured at a temperature of 200 ° C. and a load of 5 kg according to JIS K7210) of the olefin-acrylic acid alkyl ester copolymer (B) is preferably 1 to 50 g / 10 min, more preferably 2 to 2. It is 40 g / 10 min, particularly preferably 3 to 30 g / 10 min. If the MFR value is too large, the adhesive strength may be reduced. Conversely, if the MFR value is too small, the molding processability may be reduced.

  The method for producing the olefin-acrylic acid alkyl ester copolymer (B) is not limited, and a method such as copolymerization by radical polymerization in the presence of all monomers necessary for copolymerization can be employed. In addition, ethyl acrylate copolymer polyethylene (trade name “Lex Pearl EEA4200”), methyl acrylate-maleic anhydride copolymer polyethylene (trade name “Lex Pearl ET330H”), etc. are sold by Nippon Polyethylene Co., Ltd. It is also possible to use these.

  The ratio of the styrenic block copolymer (A) in the thermoplastic elastomer composition of the present invention is 30 to 85% by weight, preferably 40 to 80% by weight, more preferably 45 to 75% by weight. If the amount of the component (A) is too small, the flexibility and vibration damping property of the elastomer molded product are lowered.

  The ratio of the olefin-acrylic acid alkyl ester copolymer (B) in the thermoplastic elastomer composition of the present invention is 70 to 15% by weight, preferably 60 to 20% by weight, and 55 to 25% by weight. If the amount of the component (B) is too small, the adhesion to the adherend is lowered. Conversely, if the amount is too large, the flexibility and vibration damping properties of the elastomer molded body are lowered.

  The thermoplastic elastomer composition of the present invention includes, in addition to elastomers other than the styrene block copolymer (A) and the olefin-alkyl acrylate copolymer (B), as well as generally known thermoplastic resins as required. , Tackifier resins, fillers, reinforcing fibers, softeners, antioxidants, flame retardants, antibacterial agents, light stabilizers, UV absorbers, dyes, pigments, antiblocking agents, antistatic agents, etc. Can be blended.

  Examples of the elastomer other than the component (A) and the component (B) include, for example, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene copolymer, ethylene-butene copolymer, ethylene. -Octene copolymer, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polybutadiene rubber, polyisobutylene rubber, polyisoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, silicone rubber, fluorine rubber, urethane rubber, polyurethane heat Examples thereof include a plastic elastomer, a polyamide-based thermoplastic elastomer, and a polyester-based thermoplastic elastomer.

  Examples of the thermoplastic resin include polyethylene and modified products thereof, polypropylene, polyvinyl chloride, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyphenylene ether, and the like.

  Tackifying resins are roughly classified into natural resin-based tackifying resins and synthetic resin-based tackifying resins. Examples of natural resin-based tackifier resins include rosin resins and terpene resins. Examples of rosin resins include rosins such as gum rosin, tall rosin and wood rosin; modified rosins such as hydrogenated rosin, disproportionated rosin and polymerized rosin; rosin esters such as glycerin ester and pentaerythritol ester of modified rosin Is done. Examples of terpene resins include terpene resins such as α-pinene, β-pinene, and dipentene (limonene), as well as aromatic modified terpene resins, hydrogenated terpene resins, terpene phenol resins, and the like.

  Synthetic resin-based tackifying resins are roughly classified into addition polymerization-based tackifying resins and polycondensation-based tackifying resins. As addition polymerization type tackifying resin, aliphatic (C5) petroleum resin, aromatic (C9) petroleum resin, copolymer (C5-C9) petroleum resin, hydrogenated petroleum resin, alicyclic Petroleum resins such as petroleum resins; coumarone / indene resins; pure monomeric petroleum resins such as styrenes and substituted styrenes. Examples of the polycondensation tackifying resin include phenolic resins such as alkylphenol resins and rosin-modified phenolic resins, and xylene resins. These tackifying resins may be used alone or in combination of two or more.

  Examples of the filler include clay, diatomaceous earth, silica, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide, mica, graphite, aluminum hydroxide, various metal powders, wood powder, glass powder, ceramic powder, And inorganic fillers such as glass balloons and silica balloons; organic hollow fillers made of polystyrene, polyvinylidene fluoride, polyvinylidene fluoride copolymers, and the like.

  Examples of the softening agent include extension oils such as aromatic process oils, paraffinic process oils, and naphthenic process oils; liquid polymers such as polybutenes and polyisobutylenes.

  Examples of the antioxidant include 2,6-di-t-butyl-p-cresol and pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]. Hindered phenol compounds; thiodicarboxylate esters such as dilauryl thiodipropionate, distearyl thiodipropionate; tris (nonylphenyl) phosphite, 4,4-butylidene-bis (3-methyl-6- and phosphites such as (t-butylphenyl) ditridecyl phosphite.

The method for producing the thermoplastic elastomer composition of the present invention is not particularly limited. The styrenic block copolymer (A) and the olefin-alkyl acrylate copolymer (B) produced separately may be produced by kneading the various compounding agents added as necessary. Or you may manufacture by mixing these in the state of a solution, isolate | separating a polymer, and drying.
In the case of producing by kneading, for example, it can be produced by melt-kneading using a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, a brabender, a kneader or the like.

The elastomer molded body of the present invention is obtained by molding the above elastomer composition.
The shape of the elastomer molded body is not particularly limited, but, for example, a film having a thickness of 10 to 200 μm, a sheet having a thickness of 0.2 to 10 mm, a block shape, or other polymer material or metal plate Examples include those formed in a laminated form.

  Examples of the molding method include injection molding methods (insert molding method, two-color molding method, sandwich molding method, gas ink injection molding method, etc.), extrusion molding method, inflation molding method, T-die film molding method, laminate molding method, Examples thereof include blow molding, hollow molding, compression molding, calendar molding, rotational molding, transfer molding, vacuum molding, powder slush molding, and cast molding.

  Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples, and Reference Examples. In these examples, “parts” and “%” are based on weight unless otherwise specified.

(1) Weight average molecular weight (Mw) and content of styrene-isoprene block copolymer High-performance liquid gel permeation chromatography (GPC) using Mw of diblock copolymer as a carrier in the course of the polymerization reaction. Was measured as a polystyrene equivalent value. Further, at the end of the polymerization reaction, the triblock copolymer, the diblock copolymer, and the Mw in the coexisting state were measured in the same manner. Moreover, the content rate of the triblock copolymer and the diblock copolymer was calculated | required from the area ratio of the GPC chart. Specifically, measurement was performed using HLC8220 manufactured by Tosoh Corporation, and molecular weight calibration was performed using 12 points of standard polystyrene (500 to 3 million) manufactured by Polymer Laboratories.

(2) Styrene monomer unit content of styrene-isoprene block copolymer
^It was measured by ¹ H-NMR.

(3) Vinyl bond content of isoprene monomer unit of styrene-isoprene block copolymer
^{In the 1} H-NMR spectrum, the area of the signal (S ₁ ) around 4.7 ppm derived from the vinyl bond of the isoprene monomer unit and the area of the peak of the signal around 5.1 ppm derived from the 1,4 bond ( It was determined based on the following formula from S ₂ ).
Isoprene monomer unit vinyl bond content (%)
= [S ₁ / (S ₁ + 2S ₂ )] × 100

(4) MFR (melt viscosity) of thermoplastic elastomer composition
MFR was measured at a temperature of 200 ° C. and a load of 5 kg according to JIS K7210. The unit is g / 10 min.

(5) Hardness of elastomer molded body (Duro A)
The hardness of a 2 mm thick sheet-like elastomer molded body produced by press molding was measured according to JIS K6253.

(6) Measurement of 180 ^o peel adhesion strength of elastomer molded body A polyester film having a thickness of 25 μm, a film-shaped elastomer molded body having a thickness of 200 μm, and a stainless steel plate as an adherend are sequentially laminated, and from the stainless steel plate side. Then, heat sealing was performed at 150 ° C. for 2 seconds using a heat sealing machine to prepare a 180 ° peel test specimen. Using this test piece, the peel adhesive strength was measured at 23 ° C. according to PSTC-1 (180 ° peel adhesion test by the Adhesive Tape Committee (USA)).

(7) Measurement of shear peel strength of elastomer molded body A sheet-shaped elastomer molded body having a thickness of 2 mm and a size of 2 cm × 2 cm produced by press molding is sandwiched between two stainless steel plates, and a 180 ° peel adhesion strength test is performed. In the same manner as when the test piece was prepared, heat sealing was performed once from both sides of two stainless steel plates having a thickness of 1 mm. The obtained test piece was pulled at 23 ° C. using a tensile tester in accordance with the measurement of shear peeling described in JIS Z1541, and the force required to separate the two stainless steel plates was measured.

(8) Measurement of vibration damping property (tan δ) of elastomer molded body Using a dynamic viscoelasticity measuring device (product name “ARES”, manufactured by TA Instruments Japan), 8 mm parallel plate, initial gap 2 mm The strain tangent was measured at 23 ° C. by measuring 0.1% strain at a frequency of 1 Hz at a rate of 4 ° C./min. . The higher this value, the better the vibration damping.

(Reference Example 1)
Solvent cyclohexane 112 parts, N, N, N ′, N′-tetramethylethylenediamine in pressure-resistant reactor with stirrer. (Indicated as “TMEDA” in Table 1) 0.71 × 10 ⁻³ parts and 7.2 parts of styrene were added and stirred at a temperature of 40 ° C., and n-butyllithium 26.2 × 10 6 as an anionic polymerization initiator. ^-3 parts were added, polymerization was performed while raising the temperature to 50 ° C., and after 1 hour, a polymerization conversion rate of 100% was confirmed. Subsequently, while maintaining the temperature at 50 to 60 ° C., 40.8 parts of isoprene was added over 1 hour to continue the polymerization, and after 1 hour, a styrene-isoprene diblock copolymer was obtained at a polymerization conversion rate of 100%. Therefore, a part of the reaction solution was collected, methanol was added thereto, and GPC and ¹ H-NMR measurements were performed. The diblock copolymer had an Mw of 164,000 and a styrene monomer unit content of 15%.

Next, 6.6 × 10 ⁻³ parts of dimethyldichlorosilane as a bifunctional coupling agent was added to the reaction solution to conduct a coupling reaction to form a styrene-isoprene-styrene triblock copolymer, and after 2 hours. Then, 39.3 × 10 ⁻³ parts of methanol was added as a polymerization terminator to terminate the polymerization reaction. The resulting styrene-isoprene-styrene triblock copolymer and styrene-isoprene block copolymer mixture (hereinafter referred to as “styrene-isoprene block copolymer 1”) had a styrene monomer unit content of 15. %, The vinyl bond content of the isoprene monomer unit was 7%. The Mw of the styrene-isoprene block copolymer 1 is 201,000, and the proportion obtained from the chart area is 25% triblock copolymer and 75% diblock copolymer, and is calculated from this proportion. The Mw of the triblock copolymer was 325,000.

(Reference Examples 2 and 3)
In Reference Example 1, an anionic polymerization reaction was carried out in the same manner as in Reference Example 1 except that the amount was changed to the amount shown in Table 1, and styrene-isoprene block copolymer 2 and styrene-isoprene block copolymer 3 were obtained. Table 1 shows the characteristic values of the obtained polymer.

Example 1
70 parts styrene-isoprene block copolymer 1, 30 parts maleic anhydride-methyl acrylate copolymer polyethylene (trade name “Lexpearl ET330H”, manufactured by Nippon Polyethylene Co., Ltd., Note 1), and 1 part antioxidant Agent (trade name “Irganox 1010”, manufactured by Ciba Specialty Chemicals Co., Ltd.) is kneaded and extruded at 180 ° C. while being continuously supplied to the twin-screw extruder. Using a hot cut device, pellets having an average diameter of about 5 mm were obtained. MFR was measured using this pellet. The results are shown in Table 2.

The pellets were supplied to a single-screw T-die extruder to obtain a film having a thickness of 200 μm at a screw temperature of 160 ° C. and a die temperature of 180 ° C. Using this film, 180 ° C. peel adhesion strength was measured. The results are shown in Table 2.
The pellets are placed in a 2 mm deep mold of a hot press molding machine, preheated at 130 ° C. for 5 minutes, pressed for 2 minutes, cooled to room temperature with water, taken out from the mold, and 2 mm thick. A sheet of 150 mm × 150 mm was obtained. Using the sheet thus obtained, the hardness, shear peel strength and vibration damping were measured. The results are shown in Table 2.

  [Note 1]: Maleic anhydride-methyl acrylate copolymer polyethylene (trade name “Lexpearl ET330H”, manufactured by Nippon Polyethylene): ethylene monomer unit content 81.6%, methyl acrylate unit content 16% , Maleic anhydride unit content 2.4%, MFR10.

(Examples 2-5, Comparative Examples 1-5)
Except changing to the compounding ratio shown in Table 2, it knead | mixed similarly to Example 1, and measured the physical property of the obtained thermoplastic elastomer composition. The results are shown in Table 2.
[Note 2]: Ethyl acrylate copolymer polyethylene (trade name “Lexpearl EEA4200”, manufactured by Nippon Polyethylene Co., Ltd.): ethylene monomer unit content 80%, ethyl acrylate unit content 20%, MFR5.
[Note 3]: Post-maleic modified polyethylene (trade name “Adtex DU6310”, manufactured by Nippon Polyethylene Co., Ltd.): maleic anhydride content 2%, MFR10.

  As shown in Table 2, the molded elastomer obtained from the thermoplastic elastomer composition comprising the styrene block copolymer and the olefin-alkyl acrylate copolymer specified in the present invention has a hardness of 70 or less and is flexible. Tan δ is greater than 0.2 and has excellent vibration damping properties. Moreover, it exhibits great adhesion strength in both two types of adhesion tests, 180 ° peeling and shear peeling, and the balance between flexibility, vibration damping and adhesiveness. (Examples 1 to 5).

On the other hand, when the styrene-isoprene block copolymer 1 that is the styrene block copolymer (A) is used alone or in excess of the specified ratio, the resulting molded article has reduced adhesive strength in both types of tests ( Comparative Examples 1 and 2). On the contrary, when the olefin-acrylic acid alkyl ester copolymer (B) was used in excess of the specified ratio, the molded body was remarkably increased in hardness and vibration damping was decreased (Comparative Example 3). Even when the component (A) was used in a proportion higher than the specified amount and post-modified maleic acid polyethylene was used in combination with the component (B), the adhesive strength remained low in both tests (Comparative Example 4). When maleic acid post-modified polyethylene was used, the hardness was remarkably high and the flexibility was poor (Comparative Example 5).

  The elastomer molded body of the present invention can be used as a damping material, vibration-proofing material, sound-proofing material, etc. between layers such as metal and structural materials, which are attached to the interface or gap surface between components constituting equipment, devices and materials. Insertion sheet; Viscoelastic damper; Sealing material for structural building; Sealing material for glass window frame; Adhesive for electronic parts and precision equipment, Gasket for electronic parts and precision equipment, Damping damper, vibration-proof material and soundproofing for precision equipment Materials.

The elastomer molded body of the present invention is particularly suitable for the fields of electronic parts and precision instruments because it has few low-molecular volatile components and is excellent in moisture resistance.
In these applications, methods such as heat sealing and pressure bonding are employed to adhere the elastomer molded body of the present invention between the layers.

Claims (13)

  A thermoplastic elastomer composition comprising 30 to 85% by weight of a styrenic block copolymer (A) and 70 to 15% by weight of an olefin-acrylic acid alkyl ester copolymer (B). The styrenic block copolymer (A) includes at least one polystyrene block containing a styrene monomer unit as a main constituent unit and at least one conjugated diene polymer containing a conjugated diene monomer unit as a main constituent unit. A block copolymer comprising at least one monofin polymer block containing a block and / or a monoolefin monomer unit as a main constituent unit, and comprising 5 to 40% by weight of a styrene monomer unit The thermoplastic elastomer composition according to claim 1, which is a coalescence. The thermoplastic elastomer composition according to claim 1 or 2, wherein the styrenic block copolymer (A) has a weight average molecular weight of 50,000 to 1,000,000. The styrenic block copolymer (A) comprises at least one polystyrene block containing a styrene monomer unit as a main constituent unit and at least one polyisoprene block containing an isoprene monomer unit as a main constituent unit. The thermoplastic elastomer composition according to claim 1, which is a block copolymer of styrene-isoprene block copolymer comprising 5 to 40% by weight of styrene monomer units. The thermoplastic elastomer composition according to claim 4, wherein the styrene-isoprene block copolymer contains 30 to 95% by weight of a styrene-isoprene block copolymer. The weight average molecular weight of the styrene-isoprene diblock copolymer is 50,000 to 250,000, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 or less. The thermoplastic elastomer composition according to claim 5. The thermoplastic elastomer composition according to any one of claims 4 to 6, wherein the polystyrene block in the styrene-isoprene block copolymer has a weight average molecular weight of 8,000 to 100,000. The thermoplastic elastomer composition according to any one of claims 4 to 7, wherein a vinyl bond content in all isoprene units in the styrene-isoprene block copolymer is 30% by weight or less.   The olefin-acrylic acid alkyl ester copolymer (B) comprises olefin monomer units of 30 to 90% by weight, acrylic acid alkyl ester monomer units of 10 to 70% by weight, and maleic anhydride monomer units of 0 to 10% by weight. The thermoplastic elastomer composition according to any one of claims 1 to 8, which comprises: The olefin-acrylic acid alkyl ester copolymer (B) is a monoolefin having 2 to 10 carbon atoms and / or a diolefin having 4 to 10 carbon atoms and an alkyl alkyl ester having 1 to 8 carbon atoms in the alkyl group. The thermoplastic elastomer composition according to claim 9, which is a copolymer thereof.   The olefin-acrylic acid alkyl ester copolymer (B) is an olefin-acrylic acid alkyl ester-maleic anhydride copolymer, wherein the olefin monomer unit is 40 to 87% by weight, and the acrylic acid alkyl ester is a single amount. The thermoplastic elastomer composition according to claim 9 or 10, comprising 12 to 52% by weight of body units and 1 to 8% by weight of maleic anhydride monomer units. The MFR (value measured at a temperature of 200 ° C and a load of 5 kg according to JIS K7210) of the olefin-acrylic acid alkyl ester copolymer (B) is 1 to 50 g / 10 min. A thermoplastic elastomer composition.   The elastomer molded object formed by shape | molding the thermoplastic elastomer composition in any one of Claims 1-12.