JP2013224382A - Thermoplastic elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer that is excellent in mechanical strength, sealability and the like by using a modified acrylic rubber having no gel content and having a crosslinking point.SOLUTION: A thermoplastic elastomer is produced by dynamically crosslinking a mixture including 100 pts.mass of (Y) a modified acrylic rubber and 15-70 pts.mass of (C) a thermoplastic resin under the condition that (D) a crosslinking agent is present in an amount of 0.1-2 pts.mass. The modified acrylic rubber (Y) is produced by the grafting reaction of 100 pts.mass of (A) an acrylic rubber including (a-1) a structural unit derived from EA in an amount of 30-70 pts.mass, (a-2) a structural unit derived from BA represented by formula (1) and/or MEA in an amount of 30-70 pts.mass and (a-3) a structural unit derived from GMA in an amount of 1-5 pts.mass based on (a-1)+(a-2)=100 pts.mass, with 0.5-10 pts.mass of (B) a polyfunctional compound having both one functional group that can react with an epoxy group and at least one carbon-carbon double bond. (In the formula, X is a methylene group or oxygen).

Description

  The present invention relates to a thermoplastic elastomer obtained by dynamically crosslinking a mixture containing a modified acrylic rubber and a thermoplastic resin in the presence of a crosslinking agent.

  In recent years, thermoplastic elastomers that do not require a vulcanization process and have the same molding processability as thermoplastic resins have been widely used in the fields of automobiles, electrical / electronics, medical, food, and daily necessities as an alternative to vulcanized rubber. It is used. In particular, in a field where sealability is required, a thermoplastic elastomer of a type in which a mixture containing rubber and a thermoplastic resin is dynamically cross-linked in the presence of a cross-linking agent is used.

  As this kind of thermoplastic elastomer, for example, there is Patent Document 1 below. In Patent Document 1, a thermoplastic elastomer is obtained by dynamically crosslinking a mixture containing a thermoplastic resin such as polybutylene terephthalate (PBT) and acrylic rubber in the presence of a crosslinking agent. The acrylic rubber here is a structural unit derived from an acrylic acid alkyl ester and / or an acrylic acid alkoxyalkyl ester monomer of 20 to 99.99% by mass, and a carbon-carbon double bond such as dicyclopentenyl acrylate (DCPA). The structural unit derived from a monomer having a side chain of 0.01 to 20% by mass, the structural unit derived from an unsaturated acrylonitrile monomer from 0 to 40% by mass, and a monomer copolymerizable therewith A structural unit is comprised by 0-30 mass%.

JP 2006-124538 A

  However, in Patent Document 1, since a monomer having a carbon-carbon double bond in the side chain is used as a monomer constituting the acrylic rubber, during the copolymerization of the acrylic rubber, Acrylic rubber is gelled by the reaction of the carbon-carbon double bond in the side chain. When the acrylic rubber is gelled, the crosslinking point is lost, and the thermoplastic elastomer finally obtained has a problem that the mechanical strength, the sealing property, and the like are low.

  Accordingly, the present invention solves the above-described problems, and provides a thermoplastic elastomer that is excellent in mechanical strength, sealing properties, etc. by using a modified acrylic rubber having no gel content and having a crosslinking point. Objective.

（式中、Ｘはメチレン基または酸素である）
（２）前記アクリルゴム（Ａ）は、前記構成単位（ａ−１）を３０〜７０質量部、前記構成単位（ａ−２）を３０〜７０質量部、及び前記構成単位（ａ−１）と構成単位（ａ−２）の合計１００質量部に対して前記構成単位（ａ−３）を１〜５質量部含み、
前記変性アクリルゴム（Ｙ）は、前記アクリルゴム（Ａ）１００質量部と、前記多官能化合物（Ｂ）０．５〜１０質量部とをグラフト反応させてなり、
熱可塑性エラストマー（Ｚ）は、前記変性アクリルゴム（Ｙ）を１００質量部、及び前記熱可塑性樹脂（Ｃ）を１５〜７０質量部含む混合物を、架橋剤（Ｄ）が０．１〜２質量部存在する条件下にて架橋させてなる、（１）に記載の熱可塑性エラストマー。 For this purpose, the present invention adopts the following means.
(1) A thermoplastic elastomer (Z) obtained by dynamically crosslinking a mixture containing a modified acrylic rubber (Y) and a thermoplastic resin (C) in the presence of a crosslinking agent (D),
The modified acrylic rubber (Y) is a structural unit derived from at least one monomer selected from the structural unit (a-1) derived from an ethyl acrylate monomer and a compound represented by the following general formula (1). (A-2) and an acrylic rubber (A) containing a structural unit (a-3) derived from a glycidyl methacrylate monomer, one functional group capable of reacting with an epoxy group, and at least one carbon- A thermoplastic elastomer obtained by graft reaction of a polyfunctional compound (B) having a carbon double bond.

(Wherein X is a methylene group or oxygen)
(2) The acrylic rubber (A) includes 30 to 70 parts by mass of the structural unit (a-1), 30 to 70 parts by mass of the structural unit (a-2), and the structural unit (a-1). And 1 to 5 parts by mass of the structural unit (a-3) with respect to 100 parts by mass in total of the structural unit (a-2),
The modified acrylic rubber (Y) is obtained by graft-reacting 100 parts by mass of the acrylic rubber (A) and 0.5 to 10 parts by mass of the polyfunctional compound (B),
The thermoplastic elastomer (Z) is a mixture containing 100 parts by mass of the modified acrylic rubber (Y) and 15 to 70 parts by mass of the thermoplastic resin (C), and 0.1 to 2 parts by mass of the crosslinking agent (D). The thermoplastic elastomer according to (1), wherein the thermoplastic elastomer is crosslinked under a condition in which part is present.

  According to this invention, the monomer which has a carbon-carbon double bond in a side chain is not used as a monomer which comprises acrylic rubber (A). Therefore, the acrylic rubber does not gel during the copolymerization of the acrylic rubber (A). However, since the acrylic rubber (A) does not have a carbon-carbon double bond serving as a crosslinking point, a thermoplastic elastomer having excellent mechanical strength, sealing properties, etc. cannot be obtained as it is. Therefore, first, the acrylic rubber (A) is copolymerized without gelation, and then the polyfunctional compound (B) having at least one carbon-carbon double bond is added to the acrylic rubber (A). A modified acrylic rubber having a carbon-carbon double bond in the side chain is obtained by graft reaction. The mixture containing the modified acrylic rubber having no gel content and the crosslinking point and the thermoplastic resin (C) is dynamically cross-linked in the presence of the cross-linking agent (D), so that excellent mechanical strength and A thermoplastic elastomer having sealing properties and the like can be obtained.

  Hereinafter, the present invention will be described in detail. The thermoplastic elastomer (Z) of the present invention is obtained by dynamically crosslinking a mixture containing a modified acrylic rubber (Y) and a thermoplastic resin (C) in the presence of a crosslinking agent (D). The modified acrylic rubber (Y) has an acrylic rubber (A) containing a structural unit derived from a predetermined monomer as a main chain and a polyfunctional compound (B) having a predetermined functional group as a side chain.

[Acrylic rubber (A)]
The acrylic rubber (A) as the main chain of the modified acrylic rubber (Y) is composed of the structural unit (a-1) derived from the ethyl acrylate (EA) monomer and the compound represented by the general formula (1). At least one selected from the structural unit (a-2) derived from butyl acrylate (BA) and / or methoxyethyl acrylate (MEA) monomer and the structural unit derived from glycidyl methacrylate (GMA) monomer It is a copolymer containing (a-3).

  Specifically, in the acrylic rubber (A), the structural unit (a-1) is 30 to 70 parts by mass, preferably 40 to 60 parts by mass, and the structural unit (a-2) is 30 to 70 parts by mass, preferably 1 to 5 parts by mass, preferably 1 to 3 parts by mass of the structural unit (a-3) with respect to 40 to 60 parts by mass and 100 parts by mass in total of the structural unit (a-1) and the structural unit (a-2). Including parts. When the content of each structural unit is out of the above range, the mechanical strength, elongation, hardness and the like of the resulting thermoplastic elastomer (Z) tend to decrease. In addition, the content rate of a structural unit (a-1) and a structural unit (a-2) is structural unit (a-1): structural unit (a-2) = 30: 70-70-30 on a mass reference | standard. Preferably, 40:60 to 60:40 is more preferable.

  Acrylic rubber (A) should just polymerize each monomer used as structural units (a-1)-(a-3) by a conventionally well-known method. Specifically, a mixture containing a predetermined amount of each monomer that becomes the structural units (a-1) to (a-3) may be copolymerized in the presence of a radical polymerization initiator. The amount of radical polymerization initiator used may be about 0.1 to 5 parts by mass with respect to a total of 100 parts by mass of the monomer mixture. As the polymerization method, known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be used, and emulsion polymerization is particularly preferable.

  Examples of the emulsifier used in the emulsion polymerization include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Moreover, a fluorine-type surfactant can also be used. These emulsifiers may use only 1 type and can also use 2 or more types together. Usually, anionic surfactants are frequently used. For example, long chain fatty acid salts having 10 or more carbon atoms, rosin acid salts and the like are used. Specific examples include capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, and potassium and sodium salts of stearic acid.

  Examples of radical polymerization initiators include benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, Organic peroxides such as di-t-butyl peroxide and dicumyl peroxide can be used. Moreover, an azo compound such as azobisisobutyronitrile, an inorganic peroxide such as potassium persulfate, and a redox catalyst in which these peroxides and ferrous sulfate are combined can be used. These radical polymerization initiators may be used alone or in combination of two or more. A chain transfer agent can also be used to adjust the molecular weight of the acrylic rubber (A). As the chain transfer agent, alkyl mercaptans such as t-dodecyl mercaptan and n-dodecyl mercaptan, carbon tetrachloride, thioglycols, diterpenes, terpinolene and γ-terpinenes can be used.

  When polymerizing the acrylic rubber (A), each monomer, emulsifier, radical polymerization initiator, etc. may be charged all at once into the reaction vessel to start the polymerization, or added continuously or intermittently as the reaction continues. May be. Polymerization can be carried out at 0 to 100 ° C., preferably 0 to 80 ° C., using a reactor from which oxygen has been removed, such as nitrogen substitution. The polymerization method may be a continuous method or a batch method. The polymerization time is about 0.01 to 30 hours, preferably about 1 to 10 hours. After the completion of the polymerization, the reaction product (latex) is put into an aqueous solution of an inorganic salt such as sodium chloride or calcium chloride to be coagulated, washed with water and dried to obtain an acrylic rubber.

[Polyfunctional compound (B)]
The polyfunctional compound (B) introduces (modifies) an unsaturated group (carbon-carbon double bond) serving as a crosslinking point as a side chain into the acrylic rubber (A) obtained in advance as described above. And a graft reaction with acrylic rubber (A). For this purpose, the polyfunctional compound (B) must have one functional group capable of reacting with an epoxy group and at least one carbon-carbon double bond.

  One functional group that can react with an epoxy group is a carboxyl group, an amino group, or a hydroxyl group. In addition, examples of the polyfunctional compound (B) having at least one carbon-carbon double bond together with one functional group capable of reacting with these epoxy groups include those having a carboxyl group such as crotonic acid, oleic acid, and acrylic acid. , Erucic acid, undecylenic acid, linoleic acid, linolenic acid, etc. as those having an amino group, such as acrylamide, oleylamine, oleic acid amide, etc., those having a hydroxyl group, such as 2-hydroxyethyl methacrylate, polyethylene glycol monomethacrylate, And 10-undecen-1-ol.

[Modified acrylic rubber (Y)]
Modification of acrylic rubber (A) (grafting reaction between acrylic rubber (A) and polyfunctional compound (B)) is a method of kneading acrylic rubber (A) and polyfunctional compound (B), acrylic rubber (A) Any method such as a method of mixing the polyfunctional compound (B) in a solution prepared by dissolving the compound in an organic solvent may be used, but a method of kneading is preferable from the viewpoint of simplicity of the production method.

  The polyfunctional compound (B) is subjected to a graft reaction of 0.5 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of the acrylic rubber (A). When the polyfunctional compound (B) is less than 0.5 parts by mass or more than 10 parts by mass with respect to 100 parts by mass of the acrylic rubber (A), the mechanical strength, elongation, hardness, etc. of the resulting thermoplastic elastomer (Z) are It tends to decrease.

  When the acrylic rubber (A) and the polyfunctional compound (B) are kneaded, the modified acrylic rubber (Y) can be obtained by kneading at a predetermined temperature and cooling the obtained kneaded product. At this time, the carboxyl group, amino group, or hydroxyl group of the polyfunctional compound (B) reacts with the epoxy group of the structural unit (a-3) in the acrylic rubber (A) as the main chain, thereby forming a side chain. be introduced. The kneading temperature may be 100 to 300 ° C, preferably 150 to 250 ° C.

[Others]
In the modified acrylic rubber (Y) of the present invention, an aromatic compound, an alicyclic alcohol acrylate ester, an aromatic alcohol acrylate ester, etc., as needed, within a range that does not impair each required physical property. The structural unit derived from the 1 type (s) or 2 or more types chosen can also be included. Examples of the aromatic compound include styrene, vinyl toluene, α-methyl styrene, vinyl naphthalene, and halogenated styrene. Examples of the acrylate ester of the alicyclic alcohol include vinyl acetate, vinyl chloride, vinylidene chloride, and cyclohexyl acrylate. Examples of the acrylate ester of the aromatic alcohol include benzyl acrylate.

  Further, the modified acrylic rubber (Y) of the present invention includes other additives such as a plasticizer, a filler, a reinforcing agent, a metal oxide, a softening agent, an anti-aging agent, a processing aid, a flame retardant, or an ultraviolet absorber. An agent can also be added. As for each of the other additives, only one kind of the specific materials shown below may be added, or two or more kinds may be mixed and added.

  Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, butyl octyl phthalate, di- (2-ethylhexyl) phthalate, diisooctyl phthalate, diisodecyl phthalate, and dimethyl adipate. , Diisobutyl adipate, di- (2-ethylhexyl) adipate, diisooctyl adipate, diisodecyl adipate, octyl decyl adipate, di- (2-ethylhexyl) azelate, diisooctyl azelate, diisobutyl azelate, dibutyl sebacate, di- Fatty acid esters such as (2-ethylhexyl) sebacate and diisooctyl sebacate, trimellitic acid isodecyl ester, trimellitic acid oct In addition to trimellitic acid esters such as ester, trimellitic acid n-octyl ester, trimellitic acid isononyl ester, di- (2-ethylhexyl) fumarate, diethylene glycol monooleate, glyceryl monoricinoleate, trilauryl phosphate, trilauryl phosphate Examples include stearyl phosphate, tri- (2-ethylhexyl) phosphate, epoxidized soybean oil, and polyether ester.

  As the filler, for example, silica, heavy calcium carbonate, pepper, light calcium carbonate, very fine activated calcium carbonate, special calcium carbonate, basic magnesium carbonate, kaolin clay, calcined clay, pyroflight clay, silane-treated clay, Synthetic calcium silicate, synthetic magnesium silicate, synthetic aluminum silicate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, kaolin, sericite, talc, fine talc, wollastonite, zeolite, zonotonite, asbestos, PMF ( Processed Mineral Fiber), sepiolite, potassium titanate, elastadite, gypsum fiber, glass balun, silica balun, hydrotalcite, fly ash balun, shirasu balun, carbon Examples include balun, alumina, barium sulfate, aluminum sulfate, calcium sulfate, and molybdenum disulfide.

  Examples of the reinforcing agent include SAF carbon black, ISAF carbon black, HAF carbon black, FEF carbon black, GPF carbon black, SRF carbon black, FT carbon black, MT carbon black, acetylene carbon black, and ketjen black.

  Examples of the metal oxide include zinc white, activated zinc white, surface-treated zinc white, zinc carbonate, composite zinc white, composite active zinc white, surface-treated magnesium oxide, magnesium oxide, calcium hydroxide, ultrafine calcium hydroxide, one Examples thereof include lead oxide, red lead, and white lead.

  Examples of the softener include petroleum-based softeners, vegetable oil-based softeners, subs, and the like. Examples of petroleum softeners include aromatic, naphthenic and paraffinic softeners. Examples of plant softeners include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, and wax. Examples of the sub include a black sub, a white sub, and a dark blue sub.

  Anti-aging agents include, for example, naphthylamine, diphenylamine, p-phenylenediamine, quinoline, hydroquinone derivative, mono, bis, tris, polyphenol, thiobisphenol, hindered phenol, phosphite, Examples thereof include imidazole-based, dithiocarbamic acid nickel salt-based and phosphoric acid-based anti-aging agents. These can be used alone or in combination of two or more.

  Examples of the processing aid include stearic acid, oleic acid, lauric acid, zinc stearate, calcium stearate, potassium stearate, sodium stearate, stearylamine and the like.

  Moreover, other rubber | gum can also be mix | blended with the modified acrylic rubber (Y) of this invention as a rubber component. Examples of other rubbers include styrene-butadiene copolymer rubber, butadiene rubber, isoprene rubber, butadiene / isoprene copolymer rubber, butadiene / styrene / isoprene copolymer rubber, acrylonitrile / butadiene copolymer rubber, butyl rubber, natural rubber, and chloroprene rubber. Etc.

[Thermoplastic resin (C)]
Examples of the thermoplastic resin (C) constituting the thermoplastic elastomer (Z) together with the modified acrylic rubber (Y) include polyolefins such as polypropylene (PP) and polyethylene (PE), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). ) And the like, and polyamides (PA) such as polyamide 12 (PA12), polyamide 6 (PA6), and polyamide 66 (PA66). The melting point of the thermoplastic resin (C) is preferably as high as possible. It is because the heat resistance of the thermoplastic elastomer (Z) is improved by using the thermoplastic resin (C) having a high melting point.

[Crosslinking agent (D)]
The cross-linking agent (D) cross-links the modified acrylic rubber (Y) by dynamic heat treatment at a temperature equal to or higher than the melting point of the thermoplastic resin (C). The crosslinking agent (D) is not particularly limited as long as it is a crosslinking agent capable of crosslinking a polymer compound having a carbon-carbon double bond in the molecule. For example, dicumyl peroxide, di-t-butyl Peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butyl hydroperoxide, t-butylcumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di ( t-butylperoxin) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t-butylperoxy) -hexane, α , Α′-bis (t-butylperoxy-m-isopropyl) benzene, and other organic peroxides, as well as sulfur and phenol resins.

  In using the cross-linking agent, a cross-linking accelerator, a cross-linking aid, and the like can be used. Examples of the crosslinking accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N, N-diisopropyl-2-benzothiazolylsulfenamide, and the like. Sulfenamide compounds; 2-mercaptobenzothiazol, 2- (2 ′, 4′-dinitrophenyl) mercaptobenzothiazol, 2- (4′-morpholinodithio) benzothiazol, dibenzothiazyl Thiazol compounds such as disulfide; Guanidine compounds such as diphenylguanidine, diorthotolylguanidine, diorthonitrile guanidine, orthonitrile biguanide, diphenylguanidine phthalate; acetaldehyde-aniline reactant, butyraldehyde-aniline condensation Thing, hexamethyl Aldehyde amines such as n-tetramine, acetaldehyde ammonia or aldehyde-ammonia compounds; imidazoline compounds such as 2-mercaptoimidazoline; thiourea compounds such as thiocarbanilide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea; Thiuram compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetraoctylthiuram disulfide, pentamethylenethiuram tetrasulfide; zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, di-n- Zinc butyldithiocarbamate, zinc ethylphenyldithiocarbamate, butylphenyl Zinc thiocarbamate, sodium dimethyl dithiocarbamate, dimethyl dithiocarbamate selenium, dithio acid salt-based compounds such as dimethyl dithiocarbamate tellurium; dibutyl xanthate zinc etc. Zante - DOO compounds; compounds such as zinc white and the like.

  Examples of crosslinking aids include quinone dioxime compounds such as p-quinone dioxime; methacrylate compounds such as polyethylene glycol dimethacrylate; allyl compounds such as diallyl phthalate and triallyl cyanurate. Maleimide compounds; divinylbenzene and the like.

[Thermoplastic elastomer (Z)]
The thermoplastic elastomer (Z) is a mixture containing 100 parts by mass of the modified acrylic rubber (Y) and 15 to 70 parts by mass of the thermoplastic resin (C), and 0.1 to 2 parts by mass of the crosslinking agent (D) is present. It is dynamically crosslinked under the following conditions. Dynamic cross-linking means that cross-linking proceeds while kneading a mixture containing a modified acrylic rubber (Y) and a thermoplastic resin (C).

  For kneading the mixture containing the modified acrylic rubber (Y) and the thermoplastic resin (C), continuous extruders such as a single screw extruder, twin screw extruder, twin screw rotor type extruder, pressure type kneader, and banbury. A closed kneader such as a mixer or a Brabender mixer can be used.

  In summary, the thermoplastic elastomer (Z) of the present invention is a step (I) of copolymerizing the acrylic rubber (A), and the resulting acrylic rubber (A) and the polyfunctional compound (B) are graft-reacted. Step (II) for synthesizing modified acrylic rubber (Y), step (III) for kneading the resulting modified acrylic rubber (Y) and thermoplastic resin (C), and the resulting mixture and crosslinking agent (D ) And dynamically crosslinking to obtain the thermoplastic elastomer (Z) through the step (IV).

  The thermoplastic elastomer (Z) of the present invention has oil resistance and heat resistance, and is excellent in mechanical strength such as tensile strength and sealability. The thermoplastic elastomer (Z) is oil cooler hose, air duct hose, power steering hose, control hose, intercooler hose, torque converter hose, oil return hose, heat-resistant hose and other various hose materials, fuel hose material, bearing seal, bulk Suitable for seal materials such as stem seals, various oil seals, O-rings, packings, gaskets, various diaphragms, rubber plates, belts, oil level gauges, hose masking, pipe insulation, rolls, etc. Can do.

  Hereinafter, although the specific Example of this invention is described, this invention is not limited to this.

Example 1
In a stainless steel reactor purged with nitrogen, 150 parts by mass of water, 4 parts by mass of sodium lauryl sulfate, 4 parts by mass of sodium bicarbonate, 0.01 parts by mass of ferrous sulfate heptahydrate, 0.025 parts by mass of sodium ethylenediaminetetraacetate Parts, sodium sulfoxylate 0.25 parts by mass, ethyl acrylate (EA) 50 parts by mass as structural unit (a-1), butyl acrylate (BA) 40 parts by mass as structural unit (a-2), and Monomer comprising 10 parts by mass of methoxyethyl acrylate (MEA), 3 parts by mass of glycidyl methacrylate (GMA) as the structural unit (a-3), and 0.25 parts by mass of p-menthane hydroperoxide as the radical polymerization initiator. The body / initiator mixture was added dropwise over 2 hours, and emulsion polymerization was carried out at a reaction temperature of 30 ° C. When the polymerization conversion rate reached 100%, 0.5 part by mass of N, N-diethylhydroxylamine was added to the reaction system to stop the copolymerization reaction (reaction time 5 hours). Next, the obtained reaction product (latex) was dropped into a 1% calcium chloride aqueous solution to coagulate the acrylic rubber. Subsequently, the coagulated product was sufficiently washed with water and then dried at 80 ° C. for 24 hours to obtain an acrylic rubber.

  Next, 100 parts by mass of the obtained acrylic rubber and 1.5 parts by mass of crotonic acid as the polyfunctional compound (B) were put into a Banbury mixer heated to 180 ° C., and kneaded at a blade rotation speed of 100 rpm. Kneading was performed until the torque became constant (kneading time 20 minutes). The obtained kneaded material was taken out from the Banbury mixer and compressed into a pancake by a cooling press to obtain a modified acrylic rubber (Y-1).

  Next, 100 parts by mass of the modified acrylic rubber (Y-1) and 43 parts by mass of polypropylene as the thermoplastic resin (C) are put into a Banbury mixer heated to 180 ° C., and the torque is constant at a blade rotation speed of 100 rpm. Kneading was performed until kneading (kneading time 20 minutes). Subsequently, 1 part by mass of 2,5-dimethyl-2,5-di (t-butylperoxin) hexyne-3 (H25B) was additionally charged as a crosslinking agent, and kneading was performed until the torque became constant (kneading). Time 5 minutes). The obtained thermoplastic elastomer was taken out from the Banbury mixer and compressed into a pancake by a cooling press. Then, it shape | molded into the sheet form of thickness 2mm with the press heated at 190 degreeC, and used for various evaluation.

(Examples 2-5, Comparative Examples 1-9)
While using the monomers shown in Table 1 in the proportions shown in Table 1 to obtain an acrylic rubber in the same manner as in Example 1, while using the polyfunctional compound (B) shown in Table 1 at the proportions shown in Table 1, A modified acrylic rubber was obtained in the same manner as in Example 1 under the conditions shown in Table 1. The gel content and epoxy equivalent of each acrylic rubber and modified acrylic rubber at this time were measured by the following method. The results are shown in Table 1. In Table 1, the numerical values indicating the composition are all parts by mass.

<Gel content>
About 0.2 g of acrylic rubber or modified acrylic rubber was weighed, Soxhlet extraction using acetone as a solvent was performed for 48 hours, and the gel content was calculated by the following formula.
Gel content (%) = [weight after extraction (g) / weight before extraction (g)] × 100
<Epoxy equivalent>
In accordance with JIS K 7236, about 0.1 g of acrylic rubber or modified acrylic rubber is dissolved in 30 ml of chloroform, 20 ml of acetic acid, 10 ml of 20% by mass acetic acid tetraethylammonium bromide, crystal violet indicator (acetic acid solution) 4-6 Drops were added and titrated with a 0.1 mol / l perchloric acid acetic acid solution (0.1 mol / l HClO ₄ ) while stirring with a magnetic stirrer. The end point was when a drop of 0.1 mol / l HClO ₄ was added and green began to appear. Further, since the volume expansion coefficient of the solvent needs to be corrected by temperature, the temperature of 0.1 mol / l HClO ₄ was recorded. At the same time, a blank test without using a sample was performed to measure the titer in the same manner, and the epoxy equivalent was calculated by the following formula using the obtained titer.
Epoxy equivalent (g / eq) = (1000 × m) / [0.1 × f × (V ₁ −V ₀ ) × {1- (t−t _s ) / 1000}]
m: Sample mass (g)
V ₀ : Appropriate amount of 0.1 mol / l HClO ₄ required for the blank test (ml)
V _l : Appropriate amount of 0.1 mol / _l HClO ₄ required for this test (ml)
t: Temperature of 0.1 mol / l HClO ₄ (° C.) during the main test and blank test
t _s : temperature of 0.1 mol / l HClO ₄ at the time of standardization (° C.)
f: 0.1 mol / l HClO ₄ factor at the time of standardization

  Furthermore, a thermoplastic elastomer sheet for evaluation was molded in the same manner as in Example 1 using the thermoplastic resin and the crosslinking agent shown in Table 2 in the proportions shown in Table 2. In Table 2, all numerical values indicating the composition are parts by mass.

  With respect to the obtained thermoplastic elastomer sheets of Examples and Comparative Examples, the tensile strength, elongation, hardness, and sealability (compression set) were measured by the following methods. The results are also shown in Table 2.

<Tensile strength / elongation>
Based on JIK K 6251, tensile strength (MPa) and elongation (%) were measured at a test speed of 500 mm / min.
<Hardness>
In accordance with JIK K 6253, the hardness was measured with a spring hardness tester A type.
<Compression set>
Based on JIK K 6262, compression set (%) after compression at 120 ° C./70 h for 25% in a gear oven was measured.

From the result of Table 2, since Examples 1-5 used the modified acrylic rubber which does not have a gel part and has a crosslinking point, intensity | strength and elongation were excellent. On the other hand, since the modified acrylic rubber which does not contain a component (a-3) was used for the comparative example 1, bridge | crosslinking did not advance and intensity | strength was low. Since Comparative Example 2 used a modified acrylic rubber having an excessive amount of component (a-3), the crosslinking proceeded excessively and the elongation was low. In Comparative Example 3, a modified acrylic rubber having an insufficient component (B) was used, so that the crosslinking did not proceed and the strength was low. In Comparative Example 4, since the crosslinking was inhibited by the excessively added component (B), the strength was low. Since the comparative example 5 used the acrylic rubber which gelatinized by synthesize | combining using the monomer which has a carbon-carbon double bond in a side chain, intensity | strength and elongation were low. In Comparative Example 6, since the component (C) was too small, the strength and elongation were low. In Comparative Example 7, since the component (C) was excessive, the elongation was low. Since Comparative Example 8 did not contain the component (D), the strength was low. In Comparative Example 9, since the component (D) was excessive, the elongation was low.

Claims (2)

A thermoplastic elastomer (Z) obtained by dynamically crosslinking a mixture containing a modified acrylic rubber (Y) and a thermoplastic resin (C) in the presence of a crosslinking agent (D),
The modified acrylic rubber (Y) is a structural unit derived from at least one monomer selected from the structural unit (a-1) derived from an ethyl acrylate monomer and a compound represented by the following general formula (1). (A-2) and an acrylic rubber (A) containing a structural unit (a-3) derived from a glycidyl methacrylate monomer, one functional group capable of reacting with an epoxy group, and at least one carbon- A thermoplastic elastomer obtained by graft reaction of a polyfunctional compound (B) having a carbon double bond.

(Wherein X is a methylene group or oxygen) The acrylic rubber (A) includes 30 to 70 parts by mass of the structural unit (a-1), 30 to 70 parts by mass of the structural unit (a-2), and the structural unit (a-1) and the structural unit. 1 to 5 parts by mass of the structural unit (a-3) with respect to 100 parts by mass in total of (a-2),
The modified acrylic rubber (Y) is obtained by graft-reacting 100 parts by mass of the acrylic rubber (A) and 0.5 to 10 parts by mass of the polyfunctional compound (B),
The thermoplastic elastomer (Z) is a mixture containing 100 parts by mass of the modified acrylic rubber (Y) and 15 to 70 parts by mass of the thermoplastic resin (C), and 0.1 to 2 parts by mass of the crosslinking agent (D). The thermoplastic elastomer according to claim 1, wherein the thermoplastic elastomer is crosslinked under a condition where a part is present.