JPH0796638B2 - Thermoplastic elastomer composition - Google Patents

Description

The present invention relates to a thermoplastic elastomer composition obtained by mixing a styrene block copolymer elastomer and an aliphatic polyester.

(Prior Art) At present, a thermoplastic elastomer (hereinafter referred to as TPE) has been attracting attention as a new type of rubber. TPE exhibits rubber elasticity without the need for vulcanization, which is necessary for conventional natural and synthetic rubbers, and therefore the production process can be simplified, and because it is plasticized at high temperature, it can be easily molded. It has the advantage that scrap can be reused, and in recent years it has come to be widely used for automobile parts, hoses, tubes, and the like.

The molecular structure of TPE is characterized by cross-linking that does not rely on strong chemical bonds, that is, a system that applies some kind of constraint between polymers that is effective only at around room temperature. It is called a polymer assembly consisting of soft and hard segments. Is the typical structure of TPE. The chemical structure of the soft segment is different from that of the hard segment, and in the hybrid composition of the two, the homogenous portions are aggregated and the heterogeneous portions are phase-separated from each other to form a microscopic imbalance structure. The agglomerated portion exhibits a binding effect between the molecules.

Typical TPEs include, for example, styrene-based, olefin-based, urethane-based, ester-based, amide-based, etc.

In styrene-based TPE, polystyrene forms a frozen phase as a hard segment and binds between molecular chains, resulting in rubber elasticity. This styrene-based TPE has low hardness, high strength, small compression set at room temperature, rubber elastic properties,
Excellent low temperature characteristics. However, mechanical strength, heat resistance, weather resistance, and oil resistance are poor.

In order to compensate for such drawbacks, for example, SEBSTPE in which a butadiene portion which is a soft segment is hydrogenated has been developed. This product has improved heat resistance, oil resistance, and weather resistance, but on the other hand, poor rebound resilience.

Further, an elastomer composition (Japanese Patent Application Laid-Open No. 50-82162) prepared by blending a polystyrene block copolymer with a polyester block copolymer has been proposed. However,
This mixed elastomer has insufficient elongation and has not improved oil resistance.

(Problems to be Solved by the Invention) The present invention has been made in view of such circumstances, and an object of the present invention is to have flexibility, mechanical strength, heat resistance, and weather resistance in addition to having rubber elastic properties. The purpose is to provide a styrene-based thermoplastic elastomer composition having excellent oil resistance.

(Means for Solving the Problems) As a result of repeated studies for achieving the above object, the present invention has been achieved. That is, in the case of a styrene-based thermoplastic elastomer, a thermoplastic elastomer composition obtained by blending a styrene-based block copolymer elastomer and a specific aliphatic polyester elastomer has excellent rubber elastic properties and flexibility and mechanical properties. It was found that the strength, heat resistance, weather resistance, and oil resistance are good. It was also found that this elastomer composition was remarkably improved in moldability due to the decrease in the adhesiveness due to the styrene-based TPE.

That is, (A) a styrene block copolymer elastomer of 20 to 80% by weight; (B) an aliphatic dicarboxylic acid represented by the following formula [I], an aliphatic diol, and a general formula of the following formula [II] 80% to 20% by weight of an aliphatic polyester having at least one of a dihydroxy compound represented by the formula [III] and a monohydroxy compound represented by the following formula [III] as a constituent component; To be done.

HOOC- (CH _{2) n} -COOH [I] (wherein, n represents an integer of 0.) (In the formula, R ¹ and R ² independently represent an alkylene group, p is 3 or 4, and q and r independently represent an integer of 0 or 1 or more.) (In the formula, R ³ represents an alkylene group, l is 2 or 3, and m is an integer of 0 or 1 or more.) [Aliphatic Polyester] In the above aliphatic dicarboxylic acid, the number of carbon atoms exceeds 10. When dicarboxylic acid is used, the physical properties of the molded product obtained from the aliphatic polyester are deteriorated. As the dicarboxylic acid, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid are preferably used.

Examples of the aliphatic diol include glycol and polyalkylene oxide. Examples of the glycol include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3
-Butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, cyclopentane-1 , 2-diol, cyclohexane-1,2-
Examples include diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, which may be used alone or in combination of two or more. .

Examples of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polyhexamethylene oxide and the like, and these may be used alone or in combination of two or more kinds. When the number average molecular weight of polyalkylene oxide is small, the ability to impart flexibility to the resulting aliphatic polyester is reduced, and when it is too large, physical properties such as thermal stability of the obtained aliphatic polyester are reduced. ~ 20,000, preferably 500 ~ 50
00.

The dihydroxy compound represented by the above formula [II] is a low molecular weight compound exhibiting liquid crystallinity, the alkylene groups R ¹ and R ² are preferably ethylene groups or propylene groups, and q and r are 0 or 1
Is preferred, and 4,4 "-dihydroxy-p-terphenyl represented by the following formula [A] and 4,4-" represented by the following formula [B]
Dihydroxy-p-quaterphenyl and the following formula [C]
4,4-di (2-hydroxyethoxy) -p represented by
-Quarterphenyl and the like are preferably used.

The transition temperature of 4,4 ″ -dihydroxy-p-terphenyl [A] from the crystalline state to the liquid crystal state is 260 ° C., and that of 4,4-dihydroxy-p-quarterphenyl [B] is 336.
C., that of 4,4-di (2-hydroxyethoxy) -p-quaterphenyl [C] is 403.degree. The liquid crystal state means a state in which the compound is in a molten state and the molecules maintain the alignment state. The above hydroxy compounds [II] may be used alone or in combination.

Liquid crystal molecules generally have high crystallinity.
4 "-dihydroxy-p-terphenyl [A], 4,4-
Dihydroxy-p-quaterphenyl [B] and 4,4
-Di (2-hydroxyethoxy) -p-quaterphenyl [C] has a high transition point from the crystal to the liquid crystal state. Therefore, when these dihydroxy compounds [II] are incorporated into the polymer chain, Indicates a unique property.

That is, since the dihydroxy compound [II] shows crystallinity and its transition point is high, the dihydroxy compound [II]
Even if the compounding amount of is small, it forms a strong and heat-resistant physical crosslink. As a result, it is presumed that a thermoplastic elastomer having high heat resistance can be obtained without impairing the flexibility derived from the soft segment.

The monohydroxy compound represented by the above formula [III] is a rigid low-molecular compound having a paraphenylene skeleton,
The melting points of these compounds are extremely high, reflecting the characteristic molecular structure. Furthermore, it is known that the para-phenylene skeleton is effective as a mesogen for low molecular weight liquid crystal compounds, and it has a strong cohesive force not only in the solid state but also in the high temperature state (molten state). Is shown. Therefore, the above monohydroxy compound [II
When [I] is incorporated into the polymer terminal, it results in extremely strong and highly heat-resistant physical crosslinks, and an excellent thermoplastic elastomer with excellent heat resistance is produced.

In the monohydroxy compound represented by the above formula [III], R ³ is preferably an ethylene group or a propylene group, and m
Is preferably 0 or 1. Examples of the above monohydroxy compound include 4-hydroxy-p-terphenyl, 4-
Examples thereof include hydroxy-p-quaterphenyl, 4- (2-hydroxyethoxy) -p-terphenyl, 4- (2-hydroxyethoxy) -p-quaterphenyl and the like. The monohydroxy compounds [III] may be used alone or in combination.

Polysilicone having two hydroxyl groups and lactone in an aliphatic polyester composed of at least one of the above aliphatic dicarboxylic acid [I], aliphatic diol and dihydroxy compound [II] and monohydroxy compound [III] Alternatively, aromatic hydroxycarboxylic acid may be contained as a constituent component.

The above-mentioned poly-silicone has two hydroxyl groups, and a poly-silicone having two hydroxyl groups at the molecular ends is preferable. For example, dimethyl polysiloxane, diethyl polysiloxane having two hydroxyl groups at both ends of the molecule, Examples thereof include diphenylpolysiloxane. The lower the number average molecular weight of the polysilicone, the lower the ability to impart flexibility to the resulting polyester, and the higher it becomes.
Since it becomes difficult to form polyester, 100 to 20,000 is preferable, and 500 to 5,000 is more preferable.

The lactone is a compound that opens a ring and reacts with an acid and a hydroxyl group to add an aliphatic chain, which imparts flexibility to the polyester, and which has 4 or more carbon atoms in the ring. It is preferably a 5-membered ring to a 8-membered ring, more preferably ε-caprolactone, δ-valerolactone,
γ-butyrolactone and the like can be mentioned.

The aromatic hydroxycarboxylic acid imparts rigidity and liquid crystallinity to the polyester, and includes salicylic acid, metahydroxybenzoic acid, parahydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, 3-bromo-4-hydroxyl. Benzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3-methyl-4-hydroxybenzoic acid, 3-phenyl-4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 4-hydroxy-4'-carboxy Biphenyl and the like can be mentioned, with preference given to parahydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, and 4-hydroxy-4'-carboxybiphenyl.

Further, the above aliphatic polyester may contain an aromatic diol other than the dihydroxy compound [II] or an aromatic dicarboxylic acid as a constituent component in order to improve the mechanical properties of the polyester.

Examples of the aromatic diol include hydroquinone, resorcin, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether,
4,4'-dihydroxydiphenyl sulfide, 4,4'-
Dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, bisphenol A, 1,1-di (4-hydroxyphenyl) cyclohexane, 1,2-bis (4-hydroxyphenoxy) ethane, 1 Examples thereof include 4,4-dihydroxynaphthalene and 2,6-dihydroxynaphthalene.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, metal salts of 5-sulfoisophthalic acid, 4,4'-dicarboxybiphenyl, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxydiphenyl sulfide. ,
4,4'-dicarboxydiphenyl sulfone, 3,3'-dicarboxybenzophenone, 4,4'-dicarboxybenzophenone, 1,2-bis (4-carboxyphenoxy) ethane, 1,4-dicarboxynaphthalene, or 2,6-dicarboxynaphthalene and the like can be mentioned.

The aliphatic polyester composed of the above dihydroxy compound [II], an aliphatic diol and an aliphatic dicarboxylic acid has a lower dihydroxy compound [II] content, lowering the heat resistance, and a higher content of the dihydroxy compound [II] results in a higher elastic modulus and flexibility. Drop,
Since it becomes unsuitable as a thermoplastic elastomer, the content of the dihydroxy compound [II] is preferably 0.1 to 30 mol% in all monomers constituting the polyester, more preferably 0.5 to 20 mol%. Preferably
It is 1.0 to 10 mol%. When polyalkylene oxide or polysilicone is used as a diol other than aromatic, its constituent unit is counted as one monomer. That is,
Polyethylene oxide with a degree of polymerization of 10 is counted as 10 monomers.

Further, in the aliphatic polyester composed of the monohydroxy compound [III], the aliphatic diol and the aliphatic dicarboxylic acid, the heat resistance is decreased when the content of the monohydroxy compound [III] is decreased, and the molecular weight of the aliphatic polyester is increased when the content of the monohydroxy compound [III] is increased. Does not increase sufficiently and the physical properties are inferior, so 0.1 to 2% of all monomers constituting the aliphatic polyester
It is preferably 0 mol%. Further, the aliphatic polyester composed of the dihydroxy compound [II], the monohydroxy compound [III], the aliphatic diol and the aliphatic dicarboxylic acid is a hydroxy compound obtained by combining the dihydroxy compound [II] and the monohydroxy compound [III]. When the content is low, the heat resistance is low, and when it is high, the flexibility is not decreased and the molecular weight is not sufficiently increased. Therefore, the content is preferably 0.1 to 30 mol% in all monomers constituting the aliphatic polyester. In this case, the ratio of the dihydroxy compound [II] and the monohydroxy compound [III] is preferably in the range satisfying 0 <[III] / [II] + [III] <2/3.

The aliphatic polyester composed of the above components is
It can be produced using any of the generally known polycondensation methods listed below.

A method in which a dicarboxylic acid and a diol component (including an aliphatic diol, a dihydroxy compound, a monohydroxy compound, etc.) are directly reacted.

A method of reacting a lower ester of dicarboxylic acid and a diol component by transesterification.

A method of reacting a dicarboxylic acid halide and a diol component in a suitable solvent such as pyridine.

A method of reacting a metal alcoholate of a diol component with a dicarboxylic acid halide.

A method of reacting an acetylated diol component and a dicarboxylic acid by transesterification.

It is also possible to control the structure of the polyester obtained by changing the order of addition of the dihydroxy compound [II] during polymerization. For example, dihydroxy compound [I
When I] is charged together with dicarboxylic acid and other diol components, a random copolymer is easily obtained, and when a dihydroxy compound [II] is added at the latter stage of polymerization, a block copolymer is easily obtained. . In addition, a polyester synthesized in advance is kneaded with the dihydroxy compound [II] or an acetyl compound of the dihydroxy compound under reduced pressure heating, and a segment based on the dihydroxy compound [II] is introduced into the molecular chain by deethylene glycol or transesterification reaction. Is also possible.

In the polycondensation, a catalyst generally used in producing polyester may be used. As this catalyst, lithium, sodium, potassium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium,
Examples include metals such as tin, lead, antimony, arsenic, cerium, boron, cadmium, and manganese, organometallic compounds thereof, organic acid salts, metal alkoxides, metal oxides, and the like.

Particularly preferred catalysts are calcium acetate, diacyl stannous tin, tetraacyl stannic tin, dibutyltin oxide, dibutyltin dilaurate, dimethyltin malate, tin dioctanoate, tin tetraacetate, triisobutylaluminum, tetrabutyltitanate, germanium dioxide, and trisodium. It is antimony oxide. Two or more kinds of these catalysts may be used in combination. In addition, water, alcohol, glycol, etc., which are by-products of polymerization, are efficiently distilled off,
In order to obtain a high molecular weight polymer, the reaction system is
It is preferable to reduce the pressure to 1 mmHg or less. The reaction temperature is generally 150-350 ℃.

[Styrene block copolymer elastomer]

Styrenic block copolymer elastomers are SBS (polystyrene-polybutadiene-polystyrene type, soft segment; polybutadiene), SIS (polystyrene-polyisoprene-polystyrene type, soft segment; polyisoprene), SEBS (polystyrene-polyethylene) depending on the type of soft segment. / Polybutylene-polystyrene type, soft segment: polyethylene / polybutylene). In addition, there are types such as linear block, radial block, and multi-block depending on the connection mode of the hard segment and the soft segment, and any of the above types may be used.

In the present invention, a styrene block copolymer elastomer having a polystyrene phase of 5 to 40% by weight, a rubber phase of 60 to 95% by weight, and an average molecular weight of 5000 to 500,000 is preferably used. If the average molecular weight is less than 5000, it does not show rubber-like properties, and if it exceeds 500,000, the compatibility with other resins decreases.
And the fluidity becomes poor.

Kraton.Car:flex TR (shell chemical) is a commercially available styrene block copolymer elastomer. Solpren
e (Philippe Petroleum) Europrene SOLT (Aniche), Toughprene (Asahi Kasei), Sorprene-T (Nippon Elastomer), JSR TR (Nippon Synthetic Rubber), Charge STR (Electrochemistry), Quintac (Nippon Zeon), KratonG (Shell Chemical) , Tuftec (Asahi Kasei) and the like.

The styrene type block copolymer is generally synthesized by living anion polymerization, but it is not particularly limited thereto and can be obtained by cationic polymerization or radical polymerization.

The thermoplastic elastomer composition of the present invention is obtained by mixing the aliphatic polyester (B) synthesized as described above and the styrene block copolymer elastomer (A), and the aliphatic polyester (B) is The styrene block copolymer elastomer (A) contains 20 to 80% by weight.
It is contained in 20 to 80% by weight. In an elastomer composition containing the styrene-based copolymer block elastomer (A), when the content of the elastomer (A) is less than 20% by weight, the flexibility decreases and the compression set increases. If it exceeds 80% by weight, the mechanical strength, heat resistance, weather resistance and oil resistance will not be improved.

The mixing method of the styrene block copolymer elastomer (A) and the aliphatic polyester (B) is preferably melt mixing, specifically, a single or twin screw extruder, kneader, Banbury mixer, heating roll, plastograph, etc. Can be used.

Further, the following additives may be added to the thermoplastic elastomer composition of the present invention within a range not impairing practicality. That is, glass fiber, carbon fiber, boron fiber, silicon carbide fiber, alumina fiber, amorphous fiber, inorganic fiber such as silicon / titanium / carbon fiber, organic fiber such as aramid fiber, calcium carbonate, titanium oxide, mica,
Inorganic fillers such as talc, triphenyl phosphite, trilauryl phosphite, trisnonyl phenyl phosphite, 2-tert-butyl-α- (3-tert-butyl-4
-Hydroxyphenyl) -p-cumenylbis (p-nonylphenl) phosphite and other heat stabilizers, hexabromocyclododecane, tris- (2,3-dichloropropyl)
Flame retardants such as phosphate and pentabromophenyl allyl ether, p-tert-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,
UV absorbers such as 4,5-trihydroxybutyrophenone, butylhydroxyanisole, butylhydroxytoluene, distearylthiodipropionate, dilaurylthiodipropionate, antioxidants such as hindered phenolic antioxidants, N , N-bis (hydroxyethyl) alkylamine, alkylallyl sulfonate, antistatic agent such as alkyl sulfanate, barium sulfate,
Inorganic substances such as alumina and silicon oxide; higher fatty acid salts such as sodium stearate, barium stearate and sodium palmitate; organic compounds such as benzyl alcohol and benzophenone; highly crystallized polyethylene terephthalate, polytrans-cyclohexanedimethanol terephthalate, etc. A crystallization accelerator and the like can be mentioned.

The thermoplastic elastomer composition of the present invention is press molded,
A molded body is formed by extrusion molding, injection molding, blow molding or the like. The physical properties of the molded article can be arbitrarily changed depending on its constituent components and its blending ratio. When polyester is prepared as a thermoplastic elastomer, the molded article is preferably used for flexible molded articles such as automobile parts, hoses, belts and packings, paints, adhesives and the like.

(Example) Below, this invention is demonstrated based on an Example.

Examples 1 and 2 and Comparative Examples 1 and 2 Synthesis of Aliphatic Polyester Elastomer (B) Dimethyl adipate 268.2 was placed in a glass flask having an internal volume of 2 l equipped with a stirrer, a thermometer, a gas inlet and a distillation port.
g, ethiene glycol 313.6g and 4,4-dihydroxy-p-quaterphenyl (hereinafter referred to as DHQ) 60.9g
0.4g of calcium acetate as a monomer mixture and catalyst
And 0.13 g of germanium oxide were added. After replacing the inside of the flask with nitrogen, the temperature was raised to 180 ° C. to carry out the transesterification reaction. Methanol was distilled off along with the reaction. It takes about 2 hours to complete the transesterification reaction,
Stirring was continued. Next, the temperature inside the flask was raised to 300 ° C., and stirring was continued for 30 minutes in that state, ethylene glycol was distilled out, and the reaction mixture became uniform. Inside this flask
The polycondensation reaction was carried out for 2 hours under a reduced pressure of 1 mmHg or less. A very viscous white resin was obtained. The intrinsic viscosity of this resin was 1.0.

Aliphatic polyester elastomer (B) obtained above
And styrene block copolymer elastomer (A)
(JSR TR 2000 (B), manufactured by Japan Synthetic Rubber Co., Ltd.) was mixed at the ratio shown in Table 1 and 170 ° C using a plastograph.
And melt-kneaded for 30 minutes to obtain a thermoplastic elastomer composition. JSR TR 2000 (B) is an SBS type elastomer of styrene: butadiene = 40:60 (weight ratio),
Specific gravity 0.96, melt index 3.0g / 10min (190 ℃, 2.16k
g).

The following evaluation test was performed on the obtained elastomer composition.

(A) Tensile elongation test: No. 3 dumbbells (injection pressure 1500 kgf / cm ² , mold temperature 70 ° C., cylinder temperature 190 ° C.) were used in accordance with JIS K 6301.

(B) Oil resistance test: The elastomer composition was immersed in JIS # 3 oil at 100 ° C for 70 hours, and the volume change rate (%) of the elastomer composition after immersion was measured before the test.

(C) Weather resistance test; Weather meter: 40 ℃, Humidity: 68
The dumbbell obtained in the above (B) was irradiated with light after setting to%, and after 1 day and 14 days, the dumbbell was taken out and the elongation storage rate (%) was measured. The elongation retention was determined by measuring the tensile elongation at break according to JIS K 6301 and calculating the ratio before and after the weather resistance test. The results are shown in Table 1.

(Effects of the Invention) The elastomer composition of the present invention contains an aliphatic polyester containing a hydroxy compound that is soluble at 300 ° C. or higher as a constituent component. In this aliphatic polyester, a segment based on a dihydroxy compound or a monohydroxy compound having a high crystallinity and a high melting point is introduced into an aliphatic polyester mainly composed of an aliphatic dicarboxylic acid and an aliphatic diol. The elastomer composition of the present invention obtained by mixing the following components has properties as a thermoplastic elastomer, and also has heat resistance, weather resistance, oil resistance,
Excellent mechanical strength.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Niki 2-2 Hyakusan, Shimamoto-cho, Mishima-gun, Osaka (72) Inventor Torasuke Saito 5-17-21 Yamatedai, Ibaraki-shi, Osaka (72) Inventor Hiroki Kadomachi 1-11-3 Minami Kasugaoka, Ibaraki City, Osaka Prefecture (72) Inventor Daishiro Kishimoto 2-11-20 Mishimaoka, Ibaraki City, Osaka Prefecture Umeyama Mansion 102 (56) Reference Japanese Patent Laid-Open No. 50-79559 (JP, A)

Claims (1)

[Claims] 1. (A) 20 to 80% by weight of a styrene block copolymer elastomer; (B) an aliphatic dicarboxylic acid represented by the following formula [I], an aliphatic diol, and a general formula: 80 to 20% by weight of an aliphatic polyester containing at least one of a dihydroxy compound represented by the formula [II] and a monohydroxy compound represented by the following formula [III], and a thermoplastic elastomer composition containing: . HOOC- (CH _{2) n} -COOH [I] (wherein, n represents an integer of 0.) (In the formula, R ¹ and R ² independently represent an alkylene group, p is 3 or 4, and q and r independently represent an integer of 0 or 1 or more.) (In the formula, R ³ represents an alkylene group, l represents 2 or 3, and m represents an integer of 0 or 1 or more.)