JPH10139829A - Acrylic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition useful for e.g. sealants, capable of giving vulcanizates without needing secondary vulcanization and excellent in resistance to compressive set, by incorporating an acrylic elastomer with a specific cross-linking site which makes the composition cross-linkable with an organic peroxide. SOLUTION: This composition comprises (A) an acrylic elastomer copolymerized with a compound of the formula CH2 =CRCOO(CH2 )n OCOR'mX (R is H or a methyl; R' is CH2 or CF2 ; X is Br or I; (n) is an integer of 2 to 4; and (m) is 1 or 2), e.g. acrylic 4-difluorobromoacetoxy-n-butyl ester, at 0.1 to 10wt.%, (B) an organic peroxide, and, as required, (C) a co-cross-linking agent composed of a multifunctional unsaturated compound. The composition preferably has 4 to 10 pts.wt. of the component B based on 100 pts.wt. of the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an acrylic elastomer composition. More specifically, the present invention relates to a crosslinkable composition of an acrylic elastomer obtained by copolymerizing a halogen-containing vinyl compound capable of forming a crosslinkable group of the acrylic elastomer.

[0002]

2. Description of the Related Art Acrylic elastomers are widely used as vulcanization molding materials for various sealing materials, hoses, electric parts, etc. because of their excellent heat resistance and oil resistance. The acrylic elastomer used for such a purpose is composed of an acrylic copolymer elastomer containing alkyl acrylate or alkoxyalkyl acrylate as a main component and copolymerizing a small amount of a crosslinking site monomer.

In such an acrylic copolymer elastomer, a crosslinking reaction is efficiently performed by selecting a vulcanization system according to the kind of a crosslinking site monomer.
The crosslinking group derived from the crosslinking site monomer includes an active halogen group, an epoxy group, a carboxyl group, a hydroxyl group,
There are an amide group, a diene group, etc., and the active halogen group is 2-chloroethyl vinyl ether, vinyl chloroacetate,
It has been introduced by copolymerizing a crosslinking site monomer such as chloroethyl acrylate.

[0004] As a vulcanizing agent for the acrylic elastomer into which these active halogen groups are introduced, polyamine-based, alkali soap-sulfur (donor compound) -based vulcanizing agents and the like are generally used. Examples of vulcanization include JP-B-59-33140 and JP-A-8-53.
No. 595, etc., reports that omission of secondary vulcanization, co-crosslinking with other elastomers, and the like are reported. However, in the former, there is a problem that oil resistance is inferior because ethylene-propylene copolymer rubber is mixed, while in the latter, an acrylic elastomer containing iodine or bromine as a crosslinking site and a fluoroelastomer containing iodine or bromine are used. It is only stated that certain compositions of elastomers are co-crosslinkable.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a crosslinkable composition of an acrylic elastomer having a halogenoalkyl group crosslinkable by an organic peroxide as a crosslinking site. Has excellent normal physical properties,
In addition, it is an object of the present invention to provide a vulcanizate excellent in compression set resistance.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
General formula CH ₂ CRCRCOO (CH ₂ ) nOCOR′mX (where R is a hydrogen atom or a methyl group, and R ′ is CH ₂
A group or a CF ₂ group, X is bromine atom or iodine atom, n is 2, 3 or 4, m is a halogenoalkyl group-containing (meth) acrylic acid ester represented by 1 or 2) This is achieved by an acrylic elastomer composition containing about 0.1 to 10% by weight of a copolymerized acrylic elastomer and an organic peroxide.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A halogenoalkyl group-containing (meth) acrylate having the above general formula, which is used as a crosslinking site monomer of an acrylic elastomer, has R ′ of C
What is an H ₂ group is a known compound described in JP-A-5-127394. However, in this patent publication, this compound is only used as a surface resin component of a lithographic printing plate precursor, and is not used as a copolymer component forming an acrylic elastomer.

In Japanese Patent Publication No. 45-29511, the general formula CH ₂ CRCRCOO (CH ₂ CHR) nOCOCH ₂ XR: hydrogen atom or methyl group X: bromine atom or chlorine atom n: 1-4 An acrylic elastomer obtained by copolymerizing a halogenated (meth) acrylic acid ester is described, but the vulcanization system used is a vulcanization system generally used for other chlorinated elastomers, preferably an ammonium salt or an amine. (Derivatives), sulfur, sulfur-amines, sulfur-alkali soaps, etc. are only used, but no mention is made of organic peroxide crosslinking systems.

A halogenoalkyl group-containing (meth) acrylic acid ester, which is a copolymer component of an acrylic elastomer, comprises:
It is produced by a commonly performed esterification reaction. (1) CH ₂ = CRCOO (CH ₂ ) nOH + HOCOR'mX → CH ₂ = CRCOO (C
H ₂ ) nOCOR'mX (2) CH ₂ = CRCOO (CH ₂ ) nOH + X'COR'mX → CH ₂ = CRCOO
(CH ₂ ) nOCOR'mX (3) CH ₂ = CRCOO (CH ₂ ) nX '+ HOCOR'mX → CH ₂ = CRCOO
(CH ₂ ) nOCOR´mX

As the ω-hydroxyalkyl (meth) acrylate used as a starting material for the reaction (1), 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate and the corresponding methacrylates are mentioned. Used.
As the other starting material, halogenoaliphatic carboxylic acid, halogenoacetic acid, halogenopropionic acid, halogenoperfluoroacetic acid or perfluoropropionic acid, in which the halogen atom is a bromine atom or iodine atom, is used. The esterification reaction between these two is carried out using a dehydration condensation catalyst such as p-toluenesulfonic acid, sulfuric acid, hydrochloric acid and the like.

The esterification reaction (2) is carried out as a dehydrohalogenation reaction between an acid halide of a halogenoaliphatic carboxylic acid and ω-hydroxyalkyl (meth) acrylate. Further, the esterification reaction (3) is performed as a dehydrohalogenation reaction between ω-halogenoalkyl (meth) acrylate corresponding to ω-hydroxyalkyl (meth) acrylate and halogeno aliphatic carboxylic acid. In these reactions, X 'is generally a chlorine or bromine atom.

Note that CH ₂ = CRCOO (CH ₂ ) nOC where R ′ is CF ₂
O (CF ₂ ) mX is a novel compound.

The halogenoalkyl group-containing (meth) acrylate, which is the product of these esterification reactions, forms an active halogen group when it is copolymerized with at least one of an alkyl acrylate and an alkoxyalkyl acrylate to form an acrylic elastomer. Form crosslinkable groups.

The alkyl acrylates include, for example, methyl acrylate, ethyl acrylate, n- or iso-
Alkyl groups having 1 to 8 carbon atoms such as -propyl acrylate, n- or iso-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, and 2-cyanoethyl acrylate (e.g., cyano group (Including those having a substituent of
Is used, and ethyl acrylate or n-butyl acrylate is preferably used.

Examples of the alkoxyalkyl acrylate include methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate,
Alkoxyalkyl acrylates having an alkoxyalkyl group having 2 to 8 carbon atoms, such as 2-ethoxyethyl acrylate and 2-butoxyethyl acrylate, are used, and preferably 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are used.

At least one of these alkyl acrylates and alkoxyalkyl acrylates has a content of about 60%.
999.9% by weight, preferably about 80-99% by weight, is used in the copolymerization reaction.

Alkyl acrylates and / or alkoxyalkyl acrylates are partially substituted, specifically about 30% by weight or less, preferably about 1 to 15% by weight, with other copolymerizable monomers. May be. Examples of such a copolymerizable monomer include ethylene, propylene, vinyl chloride, vinylidene chloride, acrylonitrile, acrylamide, styrene, vinyl acetate, ethyl vinyl ether, butyl vinyl ether, alkyl methacrylate,
Hydroxyalkyl acrylate, alkoxyalkyl methacrylate, cyclohexyl acrylate, benzyl acrylate, furfuryl acrylate, lactone ring-opened product (meth) acrylate having an added side chain (JP-A-3-160
008 and 6-145257).

The halogenoalkyl group-containing (meth) acrylic acid ester copolymerized with these is present in an amount of about 0.1 to 1 in the copolymer.
It is used in the copolymerization reaction in such a proportion as to account for 0% by weight, preferably about 1 to 5% by weight. At the time of this copolymerization reaction, when the copolymerization ratio of the halogenoalkyl group-containing (meth) acrylic acid ester is less than this, a sufficient amount of active halogen groups for the purpose of the present invention is not introduced into the acrylic elastomer, and When copolymerization is carried out at a ratio of e.g.

The copolymerization reaction is carried out in the presence of a commonly used radical polymerization initiator, preferably a redox system thereof.
It is carried out by any method such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, etc., and is preferably carried out by emulsion polymerization. The polymerization temperature is generally about 5 to 80 ° C., preferably about 10 to 60 ° C., and the polymerization rate is about 90% or more. It becomes the composition of the copolymer as it is. The resulting acrylic elastomer has a Mooney viscosity of about 5-100, preferably about 20-60
Has ML _{1 + 4} (100 ° C).

The acrylic elastomer obtained by copolymerizing a halogenoalkyl group-containing (meth) acrylic acid ester, like the acrylic elastomer having another active halogen group as a crosslinkable group, is a polyamine type, a polyamine-chlorine type, an alkali soap-type. It can be vulcanized using a sulfur (donor compound) system, a triazine derivative-metal oxide system, a trithiocyanuric acid-dialkyldithiocarbamate zinc salt-based vulcanization system, but preferably by an organic peroxide. Crosslinked.

Examples of the organic peroxide include di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, and 2,5-dimethyl-2. , 5-di (tert-butylperoxy) hexyne-3,1,1-
(Tert-butyl peroxy) -3,3,5-trimethylcyclohexane, preferably 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 1,1- (tert-butyl Peroxy)
-3,3,5-trimethylcyclohexane is used. These organic peroxides are used in an amount of about 1 to 15 parts by weight, preferably about 4 to 10 parts by weight, per 100 parts by weight of the acrylic elastomer.

When an organic peroxide is used as a crosslinking agent, it is preferable to use a co-crosslinking agent comprising a polyfunctional unsaturated compound in combination. As the polyfunctional unsaturated compound, for example, ethylene glycol di (meth) acrylate,
Propylene glycol di (meth) acrylate, triallyl (iso) cyanurate, trimethylolpropanetri
(Meth) acrylate, triallyl trimellitate, N, N
'-M-phenylenebismaleimide, triacrylformal, dipropargyl terephthalate, diallyl terephthalate, tetraallyl terephthalate, triallyl phosphate, etc., and these co-crosslinking agents are about 1 to 15 parts by weight per 100 parts by weight of acrylic elastomer. , Preferably about
Used in a proportion of 5 to 10 parts by weight. If the proportion is less than this, sufficient vulcanization rate and vulcanization properties cannot be obtained, while if it is used at a higher proportion, the elongation value is remarkably reduced.

The preparation of the acrylic elastomer composition containing a vulcanizing agent such as an acrylic elastomer and an organic peroxide may be carried out, if necessary, using an acid acceptor comprising an oxide or hydroxide of a divalent metal, Phenols for adjusting the return, thiols or sulfins, reinforcing agents or fillers represented by carbon black, lubricants such as stearic acid, plasticizers and the like are further appropriately added, then an open roll mixer, a Banbury mixer, Vulcanization performed by kneading using a kneader or the like is performed at about 150 to 200 ° C.
Press vulcanization (primary vulcanization) performed for 0.5 to 15 minutes, and if necessary, gear oven vulcanization (secondary vulcanization) performed at about 120 to 180 ° C. for about 1 to 20 hours.

The acrylic elastomer according to the present invention is not only crosslinked by itself and is not only vulcanized, but also a specific fluorine-containing elastomer which can be crosslinked by an organic peroxide.
It is co-crosslinked even when blended with (fluororubber) or a diene elastomer and vulcanized.

The fluorine-containing elastomer crosslinked by an organic peroxide is a fluorine-containing elastomer containing iodine and / or bromine in the molecule. Such a fluorine-containing elastomer is obtained by homopolymerizing or copolymerizing a fluorine-containing olefin. In the case of polymerization, various iodine-containing bromine compounds, details of easily obtainable by coexisting iodine-containing compounds or bromine-containing compounds are described in, for example, JP-A-7-292198 which discloses the invention by the present applicant. Have been described. These peroxide crosslinkable fluorine-containing elastomer and acrylic elastomer are both about 5 to 95% by weight,
Preferably, it can be used by blending at a ratio of about 20 to 80% by weight.

Examples of the diene elastomer crosslinked by an organic peroxide include hydrogenated NBR and NB.
R, EPDM (ethylene-propylene-diene copolymer rubber) and the like are used, and hydrogenated NBR is preferably used. These peroxide-crosslinkable diene-based elastomers are used in a blend with an acrylic elastomer in an amount of about 0.1 to 50.
%, Preferably about 0.5 to 50% by weight.

[0027]

The acrylic elastomer composition according to the present invention has excellent normal physical properties even if secondary vulcanization is omitted.
In addition, a vulcanizate having excellent compression set resistance is provided.

[0028]

Next, the present invention will be described by way of examples.

[0029] Reference Example 1 a thermometer, a stirrer and a separable flask equipped with a nitrogen inlet tube, ethyl acrylate 96.5 parts by weight of _{CH 2 = CHCOO (CH 2)} 4 OCOCF 2 Br 3.5 〃 sodium lauryl sulfate 5.5 〃 organic peroxide (Nippon Oil & Fats product, Perbutyl H-69) 0.005 ホ ル Formaldehyde, sulfoxylic acid, dihydrate 0.01 〃 (Rongalit, Kanto Chemical Co.) Ferrous sulfate 0.0005 〃 Water 200 加 え Add enough nitrogen gas in the system And then at 40 ° C 2
The polymerization reaction was performed for an hour. The reaction mixture was salted out, sufficiently washed with water and dried to obtain an acrylic elastomer A having a Mooney viscosity ML _{1 + 4} (100 ° C.) of 41.1 at a polymerization rate of 91.8%.

[0030] In Reference Example 2 Reference Example 1, ethyl acrylate 66.5 parts by weight of n- butyl acrylate 20 〃 2-methoxyethyl acrylate 10 〃 _{CH 2 = CHCOO (CH 2)} 4 OCOCF 2 Br 3.5 〃 used as a monomer, An acrylic elastomer B having a Mooney viscosity ML _{1 + 4} (100 ° C.) of 38.2 was obtained at a polymerization rate of 92.5%.

Reference Example 3 In Reference Example 1, 97 parts by weight of ethyl acrylate CH ₂ CHCHCOO (CH ₂ ) ₂ OCOCH ₂ Br 3 と し て was used as the monomer, and the Mooney viscosity ML _{1 + 4} (100 ° C.) was 45.1. Acrylic elastomer C was obtained at a polymerization rate of 93.5%.

Reference Example 4 In Reference Example 1, 96.3 parts by weight of ethyl acrylate CH ₂ CHCHCOO (CH ₂ ) ₄ OCOCH ₂ Br 3.7 に お い て was used as the monomer, and the Mooney viscosity ML _{1 + 4} (100 ° C.) was 46.6. Acrylic elastomer D was obtained at a conversion of 93.7%.

Reference Example 5 In Reference Example 1, 96.5 parts by weight of ethyl acrylate CH ₂ CHCHCOO (CH ₂ ) ₄ OCOCH ₂ I 3.5〃 was used as the monomer, and the Mooney viscosity ML _{1 + 4} (100 ° C.) was 48.0. Acrylic elastomer E was obtained at a polymerization rate of 90.8%.

Reference Example 6 Ethyl acrylate having Mooney viscosity ML _{1 + 4} (100 ° C.) of 53.0
2-chloroethyl vinyl ether (95: 5 weight ratio) copolymer
(Nippon Mektron product Noxtite A-1095) was used as acrylic elastomer F.

Reference Example 7 In Reference Example 1, 97.5 parts by weight of ethyl acrylate CH ₂ = CHCOOCH ₂ CH ₂ Br 2.5 〃 was used as a monomer, and acrylic elastomer G having a Mooney viscosity ML _{1 + 4} (100 ° C.) of 45.7 was used. Obtained at a conversion of 91.3%.

Examples 1 to 5 and Comparative Examples 1 and 2 The acrylic elastomers A to
G 100 parts by weight, FEF carbon black 60 parts by weight Stearic acid 1 ア Organic peroxide (Nippon Oil & Fats product, Peroximon F-40) 3.95 ト リ Triallyl isocyanurate 6 加 え, kneaded with an open roll, and kneaded 180
℃, 8 minutes after press vulcanization (primary vulcanization), 175 ℃,
Oven vulcanization (secondary vulcanization) was performed for 4 hours.

With respect to the obtained primary vulcanizates and secondary vulcanizates, vulcanization properties were measured in accordance with JIS K-6301, and the compression set of the secondary vulcanizates (150 ° C., 70 hours, (25% compression)
Was measured. Further, Vulcanization characteristics were evaluated as a vulcanization torque T ₁₀ at 180 ° C.. In this evaluation, ◎ is 5 kg · cm or more, は is 4 to 5 kg · cm, and Δ is 4 kg · cm or less. The results obtained are shown in the following table.

Table Example Comparative Example 1 2 3 4 5 1 2 [Copolymer Elastomer] ABCDEFG [Vulcanization Characteristics] ○ ○ ○ ○ ◎ △ △ [Vulcanized Physical Properties of Primary Vulcanizate] Hard (JIS A) 70 65 67 67 68 67 59 100% modulus (MPa) 3.7 3.5 3.5 3.8 3.9 2.1 4.5 Tensile strength (MPa) 8.7 8.2 8.6 8.9 11.0 7.4 8.0 Elongation (%) 220 280 210 210 240 330 240 [ Secondary vulcanizate vulcanizate properties) Hardness (JIS A) 73 68 73 73 76 72 70 100% modulus (MPa) 3.7 3.6 4.7 5.0 4.2 2.5 5.5 Tensile strength (MPa) 8.8 8.3 9.5 9.5 11.2 7.3 9.6 Elongation ( %) 230 270 200 200 190 330 190 [Permanent compression set; (%)] 29 28 46 48 45 47 55

Comparative Example Acrylic Elastomer D 100 parts by weight FEF carbon black 60 1 stearic acid 1 〃 2,4,6-trimercapto-s-triazine 0.5 〃 (Nippon Zeon product TCY) Sodium stearate (Kao product NS soap) 2 When each of the components (1) and (2) was kneaded with an open roll, the dough was scorched during the kneading, and the dough was tattered, so that press vulcanization could not be performed.

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[Procedure amendment]

[Submission date] December 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

The fluorine-containing elastomer crosslinked by the organic peroxide is a fluorine-containing elastomer containing iodine and / or bromine in a molecule. Such a fluorine-containing elastomer is obtained by homopolymerizing or copolymerizing a fluorine-containing olefin. In the polymerization, it can be easily obtained by coexisting various iodine-containing bromine compounds, iodine-containing compounds or bromine-containing compounds, and details thereof are described, for example, in Japanese Patent Application Laid-Open No. Hei 7-29219 which describes the invention by the present applicant.
No. 8 publication. These peroxide-crosslinkable fluorine-containing elastomer and acrylic elastomer can be used by blending at a ratio of about 5 to 95% by weight, preferably about 20 to 80% by weight.

Claims (2)

[Claims] 1. The general formula CH ₂ CRCRCOO (CH ₂ ) nOCOR′mX (where R is a hydrogen atom or a methyl group, and R ′ is CH ₂
A group or a CF ₂ group, X is bromine atom or iodine atom, n is 2, 3 or 4, m is a halogenoalkyl group-containing (meth) acrylic acid ester represented by 1 or 2) An acrylic elastomer composition comprising an acrylic elastomer copolymerized at about 0.1 to 10% by weight and an organic peroxide. 2. The general formula: CH ₂ CRCRCOO (CH ₂ ) nOCO (CF ₂ ) mX (where R is a hydrogen atom or a methyl group, X is a bromine atom or an iodine atom, and n is 2,3 Or 4 and
m is 1 or 2), a halogenoalkyl group-containing (meth) acrylic acid ester represented by the formula: