JPH11140264A - Acrylic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an acrylic elastomer composition containing an unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer and its vulcanization system. SOLUTION: This composition comprises 100 pts.wt. of an unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer, about 0.1-5 pts.wt. of a diamine compound vulcanization accelerator, about 0.1-10 pts.wt. of a guanidine compound vulcanization accelerator and about 0.1-3 pts.wt. of a benzothiazolylsulfenamide vulcanization accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an acrylic elastomer composition. More specifically, it relates to an acrylic elastomer composition having excellent scorch stability and compression set characteristics.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 50-45031 discloses that an acrylate-butenedionic acid monoester binary copolymer or an ethylene-acrylate-butenedionic acid monoester terpolymer has a primary amino group. An elastomer composition containing a vulcanizing agent of a polyamine compound having the formula (I) and a vulcanization accelerator is described.

The vulcanization accelerators used here have a Kb value in water at 25 ° C. in the range from 10 ^{-12 to} 10 ⁶ and do not crosslink by reaction with ester groups (conjugated). ) Is considered to be a base, and specifically, the following six types of compounds are listed. (1) Inorganic weak acid alkali metal salt or alkali metal hydroxide (2) Organic weak acid alkali metal salt, alkali metal alcoholate or phenolate (3) Quaternary ammonium or quaternary phosphonium hydroxide, alcoholate, phenolate , Halides or salts with weak acids (4) tertiary amines (5) guanidine, arylguanidine or alkylguanidine (6) heterocyclic tertiary amines

Elastomer compositions containing these vulcanization accelerators together with a polyamine compound vulcanizing agent are said to have good scorch resistance. However, when the above vulcanization accelerator (1) is used, Gives only vulcanizates with inferior compression set properties due to ionic cross-linking.Vulcanization accelerators of (2) not only have insufficient scorch resistance, but also have inferior compression set properties. The vulcanization accelerators (3) and (4) show no vulcanization acceleration effect when an aromatic diamine compound vulcanizing agent is used.

[0005] The vulcanization accelerator (5) is a commonly used vulcanization accelerator, but has insufficient scorch stability and is not always satisfactory in processing safety and moldability. Not done. More specifically, the scorch time t ₅ (time until the Mooney viscosity increases by 5 points from the minimum Mooney viscosity at 125 ° C.) which is an index of scorch stability is required to be 10 minutes or more, They have not met these requirements.

Further, the compounds specifically mentioned as the vulcanization accelerator of the above (6) are imidazole, pyridine, quinoline and N-phenylmorpholine, among which imidazole is preferred. However, when imidazole is used as a vulcanization accelerator, the compression set characteristics are not satisfied at all.

As described above, the vulcanization system has problems in scorch stability and compression set characteristics. In particular, the compression set characteristics tend to decrease as the wire diameter of the member becomes smaller. A material having insufficient permanent distortion characteristics was not suitable for use as a molding material for a sealing material such as an O-ring, packing, or gasket having a small wire diameter.

Japanese Patent Application Laid-Open No. 6-99515 describes an acrylic elastomer composition containing a carboxyl group-containing acrylic elastomer, an aromatic diamine and a guanidine compound. Although an example of steam vulcanization using maleate is described, it does not satisfy the currently required level of scorch stability.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer and an acrylic elastomer composition containing the vulcanized system thereof, which provide scorch stability and compression elongation. An object is to provide a material having excellent distortion characteristics.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
100 parts by weight of an unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer, a diamine compound vulcanizing agent
0.1 to 5 parts by weight, guanidine compound vulcanization accelerator about 0.1 to 10
This is achieved by an acrylic elastomer composition containing about 0.1 to 3 parts by weight of a benzothiazolylsulfenamide compound vulcanization accelerator.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomers include monoalkyl esters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid, for example, methyl, ethyl, propyl Isopropyl, butyl, isobutyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, todecyl, etc., monoalkyl esters having 1 to 18 carbon atoms, preferably mono-n-butyl maleate, monoethyl fumarate Rate, thing
Those obtained by copolymerizing n-butyl fumarate with at least one of an alkyl acrylate and an alkoxyalkyl acrylate are used. These unsaturated dicarboxylic acid monoalkyl esters are used in an amount of about 0.5 to 10% by weight, preferably about 1 to 7
Used in percentages by weight. If this ratio is lower than this, vulcanization becomes insufficient and the compression set characteristic is deteriorated, while if it is used at a ratio higher than this, scorch is liable to occur.

The alkyl acrylate has a carbon number of
Alkyl acrylates having an alkyl group of 1 to 8, for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, and the like are used. Acrylate and n-butyl acrylate are preferred in view of the balance between oil resistance and cold resistance. In general, when the chain length of the alkyl group becomes longer,
Although effective for cold resistance, oil resistance is disadvantageous, and vice versa when the chain length is short.

The alkoxyalkyl acrylate includes alkoxyalkyl acrylates having an alkoxyalkyl group having 2 to 8 carbon atoms, such as methoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate, and the like. 2- or 3-ethoxypropyl acrylate is used, and among them, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are preferably used. Since these alkoxyalkyl acrylates have an ether group in the side chain, they have excellent balance between cold resistance and oil resistance.

In the copolymer obtained by copolymerizing an unsaturated dicarboxylic acid monoalkyl ester with at least one of an alkyl acrylate and an alkoxyalkyl acrylate, ethylene or the like can be further copolymerized. It is commercially available as DuPont product Vamac HG, and such a commercially available product can be used as it is.

Unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomers may contain other vinyl or olefin monomers such as styrene, vinyl toluene, or the like within a range that does not impair the properties (about 30% by weight or less). α
-Copolymerization of methyl styrene, vinyl naphthalene, acrylonitrile, methacrylonitrile, acrylamide, vinyl acetate, cyclohexyl acrylate, benzyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, piperylene, butadiene, isoprene, pentadiene, etc. it can.

If necessary, a polyfunctional unsaturated monomer or oligomer such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) Acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol (meth) acrylate, neopentyl glycol di
(Meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth)
Acrylate, polypropylene glycol di (meth) acrylate, bisphenol A ethylene oxide adduct diacrylate, dimethylol tricyclodecane diacrylate, glycerin dimethacrylate, 3-acryloyloxyglycerin monomethacrylate, etc. Can also be provided.

An unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer comprising these copolymer components is blended with a diamine compound vulcanizing agent and a vulcanization accelerator.

The diamine compound vulcanizing agent is preferably an aromatic diamine compound, for example, 4,4'-methylene dianiline, m-phenylenediamine, 4,4'-diaminodiphenyl ether, p-phenylenediamine, p, p'- Ethylene dianiline, 4,4 '-(p-phenylenediisopropylidene) dianiline, 4,4'-(m-phenylenediisopropylidene) dianiline, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone , 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy)
Phenyl] sulfone, 4,4'-bis (4-aminophenoxy)
Biphenol, bis [4- (4-aminophenoxy) phenyl]
Ether, 2,2-bis [4- (4-aminophenoxy) phenyl]
Hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene and the like are used, and a p-diamino-substituted product is preferably used. Besides these aromatic diamine compounds, for example, hexamethylene diamine, hexamethylene diamine carbamate, hexamethylene diamine-cinnamaldehyde adduct, hexamethylene diamine benzoate, N, N'-
Aliphatic diamine compounds such as disinnamylidene-1,6-hexanediamine, 4,4'-methylenebiscyclohexylamine, bis (4-amino-3-methyldicyclohexyl) methane, 4,4'-methylenebiscyclohexylamine-cinnamaldehyde An alicyclic diamine compound such as an adduct or a diamine-modified polysiloxane can also be used.
At least one of these diamine compound vulcanizing agents is used in an amount of about 0.1 to 5 parts by weight, preferably about 0.2 to 4 parts by weight, and more preferably about 0.5 to 100 parts by weight of the unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer. Used in a proportion of ~ 3 parts by weight. If this ratio is less than this, vulcanization will be insufficient, and the compression set characteristics will decrease,
On the other hand, if it is used at a higher ratio, scorching becomes easier.

Examples of the guanidine compound which is one of the vulcanization accelerators include, for example, diphenylguanidine, tetramethylguanidine, tetraethylguanidine, di-o-tolylguanidine, 1-o-tolylbiguanide, and di-o-tolylguanidyl dicatechol borate. Salts and the like are used, and diphenylguanidine and 1-o-tolylguanidine are preferably used. At least one of these guanidine compounds is:
It is used in an amount of about 0.1 to 10 parts by weight, preferably about 0.3 to 6 parts by weight, more preferably about 0.5 to 4 parts by weight, per 100 parts by weight of the unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer. If this ratio is less than this, the vulcanization rate will be slow, and the secondary vulcanization time will be long, making it less practical.On the other hand, if it is used at a higher ratio, vulcanization will be hindered and sufficient compression Distortion characteristics cannot be obtained.

The benzothiazolylsulfenamide compound as the other vulcanization accelerator includes, for example, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2-benzothiazolylsulfenamide, N, N-
Dicyclohexyl-2-benzothiazolylsulfenamide and the like are used, preferably N-cyclohexyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-
Benzothiazolylsulfenamide is used. At least one of these benzothiazolylsulfenamide compounds is used in an amount of about 0.1 to 3 parts by weight, preferably about 0.3 to 2 parts by weight, per 100 parts by weight of the unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer. . If this ratio is lower than this, the effect of improving the scorch stability cannot be obtained, while if it is used at a higher ratio, the compression set characteristics will be reduced.

[0021] In the acrylic elastomer composition containing the above components as essential components, reinforcing agents, fillers, antioxidants, stabilizers, plasticizers, lubricants, processing aids, and the like are added as necessary. The composition is prepared using a kneader such as an open roll, a Banbury mixer, or a kneader. The prepared composition is vulcanized by press vulcanization at about 150 to 200 ° C. for about 1 to 30 minutes and oven vulcanization (secondary vulcanization) at about 150 to 180 ° C. for about 1 to 16 hours. Sulfurized. The vulcanization molding is performed by a compression molding method, an injection molding method, a transfer molding method, or the like.

[0022]

The acrylic elastomer composition according to the present invention is excellent in scorch stability and compression set characteristics, and has no problem in metal corrosion resistance. And vulcanization molding materials such as oil seals and various hoses. In particular, it is noted that even a sealing material having a small wire diameter exhibits good compression set characteristics.

[0023]

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

Reference Example 1 In a separable flask equipped with a thermometer, a stirrer, a nitrogen gas inlet tube and a pressure reducing device, 150 parts of water (weight, the same applies hereinafter), 5.5 parts of sodium lauryl sulfate and 44 parts of ethyl acrylate, n -30 parts of butyl acrylate, 20 parts of 2-methoxyethyl acrylate and monoethyl maleate 6
Parts of a monomer mixture consisting of 100 parts by weight, and repeating degassing and nitrogen gas replacement to sufficiently remove oxygen in the system, and then adding sodium formaldehyde sulfoxylate 0.00
2 parts and 0.005 part of tertiary butyl hydroperoxide were added, and the polymerization reaction was started under room temperature conditions.
The reaction was continued until 90% was reached. The obtained aqueous latex is coagulated with an aqueous solution of sodium chloride, washed with water and dried to obtain a monoethyl maleate copolymerized acrylic elastomer.
(Acrylic elastomer A) was obtained.

Examples 1-3, Comparative Example 1 Acrylic Elastomer A 100 parts Stearic acid 1 part 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 2 parts FEF carbon black 60 parts 4,4'-diaminodiphenyl ether 0.7 parts di-o-tolylguanidine 2 parts N-cyclohexyl-2-benzothiazolylsulfenamide 0.5 part (Example 1) 1 part (Example 2) 2 parts (Example 3) 4 parts (Comparative Example 1) The above components were kneaded with an open roll, and the obtained composition was press-cured at 180 ° C. for 8 minutes and 175
Secondary vulcanization was performed in a gear oven at 4 ° C. for 4 hours.

The composition was measured for Mooney scorch (Mooney viscosity MLmin and scorch time t ₅ ) at 125 ° C. using a Mooney viscometer M200 manufactured by Shimadzu Corporation, and a vulcanized sheet and an O-ring ( (Diameter 3.1 mm), the compression set was measured at 150 ° C. for 70 hours according to JIS K-6301.

Comparative Example 2 In Example 1, N-cyclohexyl-2-benzothiazolylsulfenamide was not used.

Examples 4-5 In Example 1, 1 part of N-oxyethylene-2-benzothiazolylsulfenamide was used instead of N-cyclohexyl-2-benzothiazolylsulfenamide (Example 4) Or
Three parts (Example 5) were used.

Example 6 In Example 1, the amount of N-cyclohexyl-2-benzothiazolylsulfenamide was changed to 0.3 part, and 1 part of N-oxyethylene-2-benzothiazolylsulfenamide was further added. Used.

Examples 7 to 10 In Example 2, the following were used in place of 4,4'-diaminodiphenyl ether. (Example 7) 0.8 parts of p, p'-ethylenedianiline (Example 8) 2 parts of 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (Example 9) 4,4 ' -(p-phenylenediisopropylidene)
1.2 parts of dianiline (Example 10) 4,4 '-(m-phenylenediisopropylidene)
Dianiline 1.2 parts

Example 11 In Example 1, 1 part of hexamethylene diamine carbamate was used in place of 4,4'-diaminodiphenyl ether, the amount of di-o-tolylguanidine was 0.5 part, and N-cyclohexyl-2- The amount of benzothiazolylsulfenamide was changed to 3 parts each.

Comparative Example 3 In Example 11, N-cyclohexyl-2-benzothiazolylsulfenamide was not used.

Example 12 In Example 11, one part of N, N'-dicinnamylidene-1,6-hexanediamine was used in place of hexamethylenediaminecarbamate.

Comparative Example 4 In Example 12, N-cyclohexyl-2-benzothiazolylsulfenamide was not used.

Example 13 In Example 11, a diamine-modified polysiloxane (BY16-853U, Toray Dow Corning Silicone product, amine equivalent 385) was used in place of hexamethylenediamine carbamate.
Three parts were used.

Comparative Example 5 In Example 13, N-cyclohexyl-2-benzothiazolylsulfenamide was not used.

Example 14 In Example 1, 3.9 parts of di-o-tolyl guanidine dicatechol borate was used in place of di-o-tolyl guanidine, and the amount of 4,4'-diamino diphenyl ether was reduced.
Changed to one copy.

Comparative Examples 6 to 8 In Comparative Example 2, the amount of 4,4'-diaminodiphenyl ether was changed to 1 part and the following compound was used in place of di-o-tolylguanidine. (Comparative Example 6) 2.1 parts of N-oxyethylene 2-benzothiazolylsulfenamide (Comparative Example 7) 2.5 parts of tetraethylthiuram disulfide (Comparative Example 8) 4 parts of zinc dibutyldithiocarbamate

Table 1 shows the measurement results in the above Examples and Comparative Examples. Table 1 Mooney Scorch (125 ° C) Compression Set (%) Example MLmin (pts) t ₅ (min) Sheet O-ring Example 1 47 13 9 12 〃 2 46 17.2 10 16 〃 3 43 34.3 12 17 Comparative Example 1 43 46.5 29 25 〃 2 50 7.9 8 13 Example 4 46 12.8 9 12 〃 5 46 18.4 9 13 〃 6 47 14.5 9 12 〃 7 47 12.2 8 14 〃 8 41 12.9 9 15 〃 9 57 11.5 8 13 〃 10 56 11 8 15 〃 11 51 10 15 18 Comparative example 3 72 3.2 18 20 Example 12 48 11.1 14 17 Comparative example 4 49 7.7 15 20 Example 13 10.2 18 22 Comparative example 5 48 3.9 20 26 Example 14 48 20.9 17 19 Comparison Example 6 42 12.5 19 35 Comparative Example 7 46 10.2 22 41 〃 8 37 12.2 27 50

Reference Examples 2 to 9 The same copolymerization reaction as in Reference Example 1 was carried out using 100 parts of the monomer mixture in the proportions shown in Table 2 below to obtain an unsaturated dicarboxylic acid monoalkyl ester copolymer acrylic. Elastomers (acrylic elastomers B to G), epoxy group-containing acrylic elastomers (acrylic elastomer H) and chlorine group-containing acrylic elastomers (acrylic elastomer)
I got. Table 2 Reference Example 2 3 4 5 6 7 8 9 [monomer mixture: parts] ethyl acrylate 25.2 46 44 44 44 46 45 37.5 n-butyl acrylate 45 30 30 30 30 30 30 30 2-methoxyethyl acrylate 28 20 20 20 20 20 22 30 Monomethyl fumarate 1.8 Monoethyl fumarate 4 Monomethyl maleate 6 Monoethyl maleate 6 Mono n-butyl maleate 6 Monomethyl itaconate 4 Allyl glycidyl ether 3 Monovinyl acetate 2.5 [Acrylic elastomer] Abbreviation BCDEFGHI

Reference Examples 10 to 14 Mono-n-butyl fumarate copolymerized acrylic elastomer was obtained by using 100 parts of the monomer mixture in the proportions shown in Table 3 and conducting the same copolymerization reaction as in Reference Example 1. (Acrylic elastomers J to N) were obtained. Table 3 Reference Example 10 11 12 13 14 [monomer mixture: parts] ethyl acrylate 45 65.5 30 10 n-butyl acrylate 30 47.5 32 52.5 2-methoxyethyl acrylate 22.5 50 67 35 mono-n-butyl fumarate 2.5 2.5 2.5 3 2.5 [Acrylic Elastomer] Abbreviation JKLMN

REFERENCE EXAMPLES 15-17 The same copolymerization reaction as in Reference Example 1 was carried out using 100 parts of the monomer mixture in the proportions shown in Table 4 below, to obtain a monoethyl fumarate copolymerized acrylic elastomer (acrylic). Elastomers O to R) were obtained. Table 4 Reference Example 15 16 17 [monomer mixture: parts] ethyl acrylate 41 40 45.9 n-butyl acrylate 33 33 30 2-methoxyethyl acrylate 20 20 20 styrene 3 acrylonitrile 4 neopentyl glycol diacrylate 0.1 monoethyl fumarate 3 3 4

Examples 15 to 28 100 parts of acrylic elastomers B to G, J to N and O to R, 1 part of stearic acid 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 2 parts FEF carbon black 60 Part 4,4'-diaminodiphenyl ether 1 part di-o-tolylguanidine 3.5 parts N-cyclohexyl-2-benzothiazolylsulfenamide 1 part was added, and kneading, vulcanization and measurement were carried out in the same manner as in Example 1. Was.

Example 29 Using 100 parts of an ethylene-acrylate-maleic acid monoester copolymer (Vamac HG manufactured by DuPont),
Kneading (the amount of stearic acid was changed to 2 parts), vulcanization and measurement were performed in the same manner as in Example 15.

Comparative Example 9 100 parts of acrylic elastomer H, 1 part of stearic acid 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 2 parts FEF carbon black 60 parts N-cyclohexyl-2-benzothiazolylsulfen One part of amide and 2 parts of ammonium benzoate were added, and kneading, vulcanization and measurement were carried out in the same manner as in Example 1.

Comparative Example 10 100 parts of acrylic elastomer I, 1 part of stearic acid 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 2 parts FEF carbon black 60 parts N-cyclohexyl-2-benzothiazolylsulfen Amide 1 part 2,4,6-trimercapto-s-triazine 0.5 part Zinc dibutyldithiocarbamate 1.5 parts was added, and kneading, vulcanization and measurement were carried out in the same manner as in Example 1.

In the above Examples 15 to 29 and Comparative Examples 9 to 10,
The results obtained are shown in Table 5 below. Table 5 AcrylicMoony scorch Compression set An example Elastomer MLmin (pts) t ₅ (min) Sheet O-ring   Example 15 B 11.1 42 9 15 〃 16 C 10.0 82 12 16 〃 17 D 13.7 46 14 18 〃 18 E 16.4 42 15 20 〃 19 F 15.4 44 13 16 〃 20 G 12.8 52 10 15 〃 21 J 11.9 44 9 15 〃 22 K 12.2 48 8 16 〃 23 L 12.6 57 8 13 〃 24 M 11.2 53 6 14 〃 25 N 12.5 46 6 5 〃 26 O 13.1 54 11 16 〃 27 P 13.1 54 12 17 〃 28 Q 14.5 55 13 15 〃 29 Vamac 18.4 31 14 22 Comparative Example 9 H 5.8 46 27 38 〃 10 I 4.8 48 15 25

Claims (2)

[Claims] 1. An unsaturated dicarboxylic acid monoalkyl ester copolymerized acrylic elastomer 100 parts by weight, a diamine compound vulcanizing agent about 0.1 to 5 parts by weight, a guanidine compound vulcanizing accelerator about 0.1 to 10 parts by weight, and benzothiazolyl sulfone An acrylic elastomer composition comprising about 0.1 to 3 parts by weight of a phenamide compound vulcanization accelerator. 2. The acrylic elastomer composition according to claim 1, which is used as a molding material for a sealing material.