JPH0370760A - Acrylic rubber composition - Google Patents

Abstract

PURPOSE:To obtain a composition having high vulcanization rate and giving a vulcanized product having excellent heat-resistance, oil-resistance, etc., by compounding a specific amount of a quaternary ammonium salt or a quaternary phosphonium salt to an acrylic rubber containing epoxy group and cyanoalkyl ester group. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. of an acrylic rubber composed of (A1) 30-99.8wt.% of an alkyl acrylate or alkoxyalkyl acrylate, (A2) 0.1-10wt.% of a monomer containing epoxy group, (A3) 0.1-60wt.% of a cyanoalkyl (meth)acrylate expressed by formula (R<1> is H or methyl; R<2> is cyano-substituted alkyl) and (A4) 0-50wt.% of a monomer copolymerizable with the above monomers with (B) 0.1-10 pts.wt., preferably 0.5-5 pts.wt. of a quaternary ammonium salt or a quaternary phosphonium salt.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a novel acrylic rubber vulcanization composition that vulcanizes rapidly and provides a vulcanizate with excellent heat resistance, oil resistance, and compression set. It is related to.

[Prior Art] Acrylic rubber is known as a rubber with excellent heat resistance and oil resistance, and is widely used mainly in automobile parts. Acrylic rubber is a copolymer of an acrylic ester as a main component and an active monomer that acts as a crosslinking point. Typical monomers used as crosslinking points include glycidyl acrylate, glycidyl methacrylate,
Epoxy group-containing monomers such as allyl glycidyl ether have been known.

Polyamines, ammonium salts such as ammonium benzoate, dithiocarbamates such as zinc dimethyldithiocarbamate, etc. are usually used as vulcanizing agents for acrylic rubber that have epoxy groups as crosslinking points, but the vulcanization rate is low and unsatisfactory. There was a problem in that a long post-vulcanization process was required to obtain a vulcanizate with good vulcanization properties.

[Problems to be Solved by the Invention] As a result of various studies in order to solve the above-mentioned problems, the present inventors discovered that the acrylic rubber containing epoxy groups and cyanoalkyl ester groups as crosslinking points was prepared using a quaternary ammonium salt. By vulcanizing using and/or a quaternary phosphonium salt as a vulcanizing agent, it is possible to increase the vulcanization rate and obtain a vulcanized product having sufficiently satisfactory physical properties in a short vulcanization time. I discovered that it can be done.

[Means for Solving the Problems] The present invention provides 1) acrylic acid alkyl esters or acrylic acid alkoxyalkyl esters, 30.0 to 9
9.8% by weight, 2) Epoxy group-containing monomer, 0.1-1
0% by weight, 3) At least one acrylic acid cyanoalkyl ester or methacrylic acid cyanoalkyl ester represented by the following formula (I) (where R is hydrogen or a methyl group, and R2 is a cyano group-substituted alkyl group) ester,
0.1 to 60% by weight, and 4) a monomer copolymerizable with these, 0.0 to 100 parts by weight of acrylic rubber having a polymerization composition of 0 to 50% by weight, and 0.1 to 60% by weight of quaternary ammonium salts or quaternary phosphonium salts. This is a vulcanizable rubber composition containing 1 to 10 parts by weight.

The acrylic rubber used in the present invention includes (A) 3060 to 99.8% by weight of acrylic acid alkyl esters or acrylic acid alkoxyalkyl esters (B) 0.1 to 10% by weight of epoxy group-containing monomers (C ) 0.1 to 60% by weight of at least one acrylic acid cyanoalkyl ester or methacrylic acid cyanoalkyl ester represented by formula (I) (D) Polymerization composition of 0 to 50% by weight of a monomer copolymerizable with these It is a copolymer that has the composition and is in a rubbery state at room temperature.

Examples of the acrylic esters and alkoxyalkyl acrylates of component (A) include methyl acrylate, ethyl acrylate, n-butyl acrylate, Lso-butyl acrylate, tert-butyl acrylate, and propyl acrylate. , n-octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, and other acrylic acid alkyl esters having an alkyl group of 1 to 20 carbon atoms: methoxymethyl acrylate;
Examples include alkoxyalkyl acrylates having an alkoxyl group or an alkylene group having 1 to 4 carbon atoms, such as methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, and methoxyethoxyethyl acrylate.

These can be used alone or in combination of two or more.

Examples of the epoxy group-containing monomer of component CB) include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and vinyl glycidyl ether. These can be used alone or in combination of two or more.

Component (C) is acrylic acid cyanoalkyl ester or methacrylic acid cyanoalkyl ester represented by formula (I), and examples of R2 in the formula include 2-cyanoethyl group, 2-cyanopropyl group, 2-cyanopropyl group. base, 3
-cyanopropyl, 2-cyanobutyl group, 3-cyanobutyl group, etc. Specific examples of acrylic acid cyanoalkyl ester or methacrylic acid cyanoalkyl ester include 2-cyanoethyl acrylate, 2-cyanopropyl acrylate, 3-cyanopropyl acrylate, 2-cyanobutyl acrylate, and 2-cyanoethyl methacrylate. , 2-cyanopropyl methallylate, 3-cyanopropyl methallylate, and 2-cyanobutyl methallylate. Among these, 2-cyanoethyl acrylate and 2-cyanoethyl methacrylate are particularly preferred. These can be used alone or in combination of two or more.

Component (D) is a monomer copolymerizable with the above components (A) to (C), and includes methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, lauryl methacrylate, stearyl methacrylate, etc. Methacrylic acid alkyl ester in which the alkyl group has 1 to 20 carbon atoms: methacrylic acid alkoxyalkyl ester such as methoxymethyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxyethyl methacrylate, methoxyethoxyethyl methacrylate: acrylic Two general formulas of hydroxyalkyl esters of acrylic acid or methacrylic acid, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate, 3 (where R3 is hydrogen or Methyl group, R4 has 1 carbon number
-8 alkyl group or alkoxyalkyl group having 3 to 8 carbon atoms, the number average value of n is 1 to 10) Alkrylic acid ester or methacrylic ester of ε-caprolactone oligomer: vinyl acetate, vinyl propionate Vinyl esters such as: styrene,
Aromatic vinyl compounds such as α-methylstyrene; Vinyl or vinylidene nitrile compounds such as acrylonitrile and methacrylonitrile; α- such as ethylene and propylene
Olefins: Conjugated dienes such as butadiene and isoprene:
Dimethyl maleate, diethyl maleate, di-n-butyl maleate, dimethyl fumarate, diethyl fumarate,
Alkyl group such as di-n-butyl fumarate has 1 to 2 carbon atoms
Dialkyl esters of unsaturated dicarboxylic acids of 0: dialkoxyalkyl esters of unsaturated carboxylic acids such as dimethoxyethyl maleate and dimethoxyethyl fumarate: vinyl ketones such as methyl vinyl ketone and ethyl vinyl ketone. These can be used alone or in combination of two or more.

The quaternary ammonium salt and quaternary phosphonium salt used in the present invention are compounds represented by the following formula. - Y in the formula is a nitrogen or phosphorus atom, and R5-R8 are hydrocarbon groups having about 1 to 25 carbon atoms such as alkyl groups, alkoxyalkyl groups, polyoxyalkylene groups, aryl groups, and alkylaryl groups; At least one of them may contain an unsaturated bond or be substituted with a hydroxyl group. Furthermore, 2 or 3 of R5-R8
may form a heterocycle with a nitrogen atom or a phosphorus atom. X- is an anion derived from an inorganic or organic acid in which an acidic hydrogen ion is bonded to a halogen or oxygen;
I C104BF-BI3-'' R803H8
O4ROSORCOOH2PO4 ROPO'' (RO) 2 P 02 H (R in the formula represents an alkyl group, alkylaryl group, alkoxyalkyl group, or aryl group having about 1 to 25 carbon atoms)
Examples include anions such as

Examples of quaternary ammonium salts include tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetramethylammonium cy)luenesulfonate, tetramethylammonium sulfate, tetraethylammonium chloride, tetraethylammonium bromide,
Tetraethylammonium iodide, tetra n-butylammonium chloride, tetra n-butylammonium bromide, tetra n-butylammonium hydrogen sulfite, tetra n-butylammonium verchlorate, tetra n-butylammonium phosphate, tetra n-butylammonium acetate, Tetra n-butylammonium borohydride, decyltrimethylammonium bromide, dodecyltrimethylammonium chloride, n-hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium iodide, benzylhexadecyldimethylammonium chloride, phenyl Triethylammonium chloride, benzyldimethylethylammonium chloride, (
2-methoxyethoxyethyl) ammonium chloride, choline chloride, 1-pyridinium chloride, hexadecylpyridinium bromide, 2,4゜6-trimethylpyridinium p-toluenesulfonate, 1,8
Examples include -diazabicyclo(5,4,0)undecene-7-benzylammonium chloride, hexadecyltrimethylalkylphenoxypoly(ethyleneoxy)ethylammonium phosphate, and the like.

Examples of quaternary phosphonium salts include benzyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, methyltriphenylphosphonium sulfate, hexadecyltriphenylphosphonium promade, ethyltriphenylphosphonium chloride, amyltriphenylphosphonium bromide, and tetran-
Examples include butylphosphonium bromide, tetraphenylphosphonium bromide, triokdylphenylphosphonium dimethyl phosphate, trioctylphenylphosphonium acetate, bromomethyltriphenylphosphonium bromide, allyltriphenylphosphonium bromide, and the like.

These quaternary ammonium salts or quaternary phosphonium salts can be used alone or in combination of two or more.

The amount of quaternary ammonium salt or quaternary phosphonium salt used is 0 parts per 100 parts by weight of the acrylic copolymer rubber.
．． The amount is 1 to 10 parts by weight, preferably 0.5 to 5 parts by weight. If the amount used is less than 0.1 part by weight, the vulcanization rate is low and a vulcanizate with satisfactory physical properties cannot be obtained, or it takes a long time to obtain a vulcanizate with satisfactory physical properties. If the amount exceeds 1 part by weight, the vulcanization rate will be extremely high and processing stability and storage stability will be impaired.

The vulcanized composition of the present invention has the acrylic rubber described above
grade ammonium salts or quaternary phosphonium salts, and reinforcing agents, fillers, stabilizers commonly known in the rubber industry,
It is prepared by adding plasticizers, processing aids, etc. and mixing with a roll or a kneader such as a Banbury. The resulting composition is molded into a desired shape and further vulcanized to form a final product. Vulcanization is usually 120℃
The heating is carried out at the above temperature, preferably 150 to 250°C, for 1 to 60 minutes. If necessary, further increase the temperature to 150 to 200℃.
Post-vulcanization is carried out at a temperature of from 1 to 24 hours.

The composition of the present invention has a high vulcanization rate, compared to the use of conventional vulcanizing agents such as ammonium benzoate or zinc dimethyldithiocarbamate, which are known as vulcanizing agents for acrylic rubber and have epoxy groups as crosslinking points. As a result, a vulcanized product having satisfactory mechanical strength and compression set can be obtained in a shorter vulcanization time, and the vulcanization time can be significantly shortened.

The vulcanizate obtained from the composition of the present invention has excellent heat aging resistance, oil resistance, compression set, and weather resistance, and has excellent heat aging resistance, oil resistance, compression set, and weather resistance.
Various sealing materials such as rings, gaskets, oil seals, etc.
It can be widely and effectively used for various hoses, diaphragms, etc.

[Example] The present invention will be specifically explained below using examples.

In the following description, parts represent parts by weight, and % represents weight %.

Acrylic rubber having the composition shown in Table 1 was prepared by a conventional emulsion method. The composition of each acrylic rubber was determined by C-NMR and elemental analysis.

Examples 1 to 3 and Comparative Examples 1 to 3 100 parts of acrylic rubber listed in Table 2, 1 part of stearic acid
50 parts of MAF carbon black, and a predetermined amount of the vulcanizing agent listed in Table 2 were kneaded using an 8-inch open roll to prepare a blend.

JIS Mooney scorch time of the resulting compound
Measured according to K-6300. The resulting mixture was
Press vulcanization at 0℃ for 20 minutes, and further in the oven at 150℃.
A vulcanizate was obtained by post-vulcanization at ℃ for 4 hours. The physical properties of the obtained vulcanizates were evaluated according to JIS K-6301. The results are shown in Table 2, and the vulcanization curves of each compound are shown in FIG. Here, the vulcanization curve is calculated using a Monsanto rheometer.
Measurement was carried out at 70°C and vibration angle of 3°.

Examples 4 to 6 and Comparative Examples 4 to 6 100 parts of acrylic rubber shown in Table 3, 1 part of stearic acid,
50 parts of MAF carbon black and a predetermined amount of the vulcanizing agent listed in Table 3 were kneaded using an 8-inch open roll to prepare a blend. The Mooney scorch time of the resulting formulation was measured according to JIS K-6300.

The resulting compound was press-vulcanized at 170°C for 20 minutes, and further vulcanized in an oven at 150°C for 4 hours to obtain a vulcanized product. The physical properties of the obtained vulcanizate are determined according to JIS K
Table 3 shows the results of evaluation according to -6301, and FIG. 2 shows the vulcanization curves at 170°C of each formulation.

Examples 7 to 11 100 parts of acrylic rubber shown in Table 4, 1 part of stearic acid,
50 parts of MAF carbon black and a predetermined amount of the vulcanizing agent listed in Table 4 were kneaded using an 8-inch open roll to prepare a blend. The Mooney scorch time of the resulting formulation was measured according to JIS K-6300.

The resulting compound was press-vulcanized at 170°C for 20 minutes, and further vulcanized in an oven at 150°C for 4 hours to obtain a vulcanized product. The physical properties of the obtained vulcanizate are determined according to JIS K
Table 4 shows the results of evaluation according to -6301, and FIG. 3 shows the vulcanization curves at 170°C of each formulation.

[Effects of the Invention] As is clear from the above results, the composition of the present invention has a high vulcanization rate and provides a vulcanized product with satisfactory physical properties, particularly excellent compression set, in a short vulcanization time.

[Brief explanation of drawings]

Figure 1 shows the vulcanization curves of the compositions of Examples 1 to 3 and Comparative Examples 1 to 3. Figure 2 shows the vulcanization curves of the compositions of Examples 4 to 6 and Comparative Examples 4 to 6. Figure 3 shows the vulcanization curves of the compositions of Examples 4 to 6 and Comparative Examples 4 to 6. Figure 2 shows the vulcanization curves of compositions of ~11.

Claims (1)

[Claims] (1) 1) Acrylic acid alkyl esters or acrylic acid alkoxyalkyl esters, 30.0 to 99.
8% by weight, 2) Epoxy group-containing monomer, 0.1 to 10% by weight, 3) Formula ▲ Numerical formula, chemical formula, table, etc. ▼ (Here, R^1 is hydrogen or methyl group, R^2 is a cyano group-substituted alkyl group.) At least one acrylic acid cyanoalkyl ester or methacrylic acid cyanoalkyl ester represented by
．． 1 to 60% by weight, and 4) a monomer copolymerizable with these, 100 parts by weight of acrylic rubber having a polymerization composition of 0 to 50% by weight, quaternary ammonium salts or quaternary phosphonium salts, 0.1 -10 parts by weight of a vulcanizable rubber composition.