JP3235341B2 - Composition for vulcanization of blended rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanizable composition of an epichlorohydrin polymer rubber and an epoxy group-containing acrylic rubber having improved physical properties.

[0002]

2. Description of the Related Art It is known that a blend rubber of an epichlorohydrin rubber and an epoxy group-containing acrylic rubber is vulcanized with a conventionally known vulcanizing agent, for example, 2-mercaptoimidazoline. It is also known that this vulcanized rubber has both the effect of improving the heat aging resistance of the epoxy-based acrylic rubber and the fuel oil resistance of the epichlorohydrin-based polymer rubber. However, effective vulcanizing agents for each of these are usually different, and vulcanization rates are different from each other even for vulcanizing agents common to both, so that they are not necessarily in terms of physical properties on processing or after vulcanization. Sufficient results have not been obtained. That is, in the above vulcanizing agent, 2-mercaptoimidazoline, the vulcanization rate of the epoxy group-containing acrylic rubber is low, and therefore, the vulcanized product of the rubber blended with the epichlorohydrin polymer rubber has satisfactory compression set, for example. Results have not been obtained.

For the purpose of solving the above technical problem, the present applicant uses a 2,3-dimercaptopyrazine derivative or a 2,3-dimercaptoquinoxaline derivative and an acid acceptor for the above-mentioned blended rubber. A vulcanizable rubber composition having excellent vulcanizability containing a metal compound, for example, a compound of Group II metal of the periodic table such as magnesia, slaked lime, calcium silicate, or a compound of a group IVA metal of the periodic table. (Japanese Patent Laid-Open No. 58-11843).
issue). However, the vulcanizing composition using an acid acceptor exemplified herein has a problem in storage stability, such as vulcanization during storage, the viscosity increases, and shaping becomes difficult. Improvement was desired.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to an epichlorohydrin polymer rubber which has a rapid vulcanization rate and improved vulcanization properties as described above, and which has excellent long-term storage stability, and an epoxy group-containing rubber. An object of the present invention is to provide a composition for vulcanizing a blend rubber with an acrylic rubber.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above-mentioned blended rubber composition, and as a result, it has been found that a specific 2, 3
The present invention has been completed by finding that the above-mentioned object can be achieved by blending hydrotalcites as a metal compound with a dimercaptopyrazine derivative or a 2,3-dimercaptoquinoxaline derivative.

The present invention relates to (c) a rubber blend composed of (a) 40 to 99% by weight of an epichlorohydrin polymer rubber and (b) 1 to 60% by weight of an epoxy group-containing acrylic rubber; 0.1 to 10 parts by weight of a 2,3-dimercaptopyrazine derivative represented by the following general formula (I) or a 2,3-dimercaptoquinoxaline derivative represented by the following general formula (II), and (d) hydrotal It is a composition for vulcanizing a blend rubber, comprising 0.1 to 20 parts by weight of sites.

[0007]

Embedded image (However, R ¹ R ² R ³ R ⁴ R ⁵ and R ⁶ may be the same or different and represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

The epichlorohydrin polymer rubber of the present invention is a generic term for epichlorohydrin homopolymer rubber or a copolymer rubber of epichlorohydrin and other epoxides. Examples thereof include polyepichlorohydrin rubber, epichlorohydrin-allyl glycidyl ether copolymer rubber, Homopolymer rubbers such as epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, binary copolymer rubbers, and terpolymer rubbers are typical examples.

In the present invention, these are used as a single rubber or a mixed rubber of two or more. In the case of a copolymer rubber, its constituent component, epichlorohydrin, is 20%.
It is preferably from 99 to 99 mol% and from 1 to 80 mol% of other epoxides in view of physical properties of the vulcanized product. For example, in the above epichlorohydrin-allyl glycidyl ether copolymer rubber, epichlorohydrin 80-99 mol%, rubber of allyl glycidyl ether 1-20 mol%, and in epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin 25-90 mol%, Ethylene oxide 10
In the case of a rubber of about 75 mol% and epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, a rubber of 24 to 80 mol% of epichlorohydrin, 19 to 75 mol% of ethylene oxide, and 1 to 20 mol% of allyl glycidyl ether is preferably used. .
Further, the molecular weight of M _{1 + 4 at} 100 ° C., which is usually used by Mooney viscosity display, of about 30 to 150 is used as it is.

The acrylic rubber containing an epoxy group used in the present invention is an acrylic acid ester monomer of 40 to 9
9.9% by weight, 10 to 0.1% by weight of an epoxy group-containing monomer as a vulcanizing component and 30 to 0% by weight of at least one other monomer copolymerizable with these monomers. It is a copolymer consisting of As acrylic acid ester monomers,
Examples include alkyl acrylate, alkoxy acrylate, alkylthioalkyl acrylate, cyanoalkyl acrylate, and the like. Specific examples of these include ethyl acrylate, butyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, and ethylthioethyl acrylate. Epoxy group-containing monomers include allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate and the like. Other copolymerizable monomers include acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, isobutylene, acrylamide, vinyl acetate, vinyl compounds such as vinylidene chloride or vinylidene compounds, divinylbenzene, diallyl phthalate, and alkylene glycol. There are polyene compounds such as diacrylate, alkylene glycol dimethacrylate, and trimethylolpropane triacrylate. Its molecular weight is ML _{1 + 4} 100 ° C. which is usually used by Mooney viscosity display.
Those having about 20 to 100 are used as they are.

The blending ratio of the blended rubber in the composition of the present invention is from 40 to 9% of epichlorohydrin polymer rubber.
9% by weight, 1-60% by weight of epoxy group-containing acrylic rubber
Preferably, the former is 45 to 95% by weight, and the latter is 5 to 95% by weight.
It is in the range of 5 to 5% by weight. If the epichlorohydrin-based polymer rubber is less than the above range, the vulcanization rate of the composition decreases, while if the epoxy group-containing acrylic rubber is less than the above range, substantially no improvement in the heat resistance of the vulcanized product can be expected. .

Examples of the 2,3-dimercaptopyrazine derivative represented by the general formula (I) of the composition of the present invention include pyrazine-2,3-dithiocarbonate, 5-ethylpyrazine-2,3-dithiocarbonate, 5,6-dimethylpyrazine-2,3-dithiocarbonate, 5-n-butylpyrazine-2,3-dithiocarbonate and the like can be mentioned. Examples of the 2,3-dimercaptoquinoxaline derivative represented by the general formula (II) include quinoxaline-2,3
-Dithiocarbonate, 6-methylquinoxaline-2,
Examples thereof include 3-dithiocarbonate, 6-isopropylquinoxaline-2,3-dithiocarbonate, and 5,8-dimethylquinoxaline-2,3-dithiocarbonate. Of these, 6-methylquinoxaline-2,3-dithiocarbonate is particularly preferred. The amount of the vulcanizing agent represented by the general formula (I) or (II) is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight based on 100 parts by weight of the total amount of the blended rubber. Used. If the compounding amount is less than this range, the vulcanization rate decreases, while if it exceeds this range, the obtained vulcanizate becomes too rigid to obtain the properties normally expected of a rubber vulcanizate.

[0013] The component (c) used in the present invention
Talcite is represented by the following general formula (III) Mg_xAl_y(OH)_{2x + 3y-2} CO_Three ・ WH_Two O (III) (where x represents 1 to 10, y represents 1 to 5, w represents a real number)
Is shown. Illustrating these compounds is Mg_4.5 Al
_Two (OH)₁₃CO_Three ・ 3.5H_Two O, Mg_4.5 Al_Two 
(OH)₁₃CO_Three , Mg_Four Al_Two (OH)₁₂CO _Three ・
3.5H_Two O, Mg₆ Al_Two (OH)₁₆CO_Three ・ 4H_Two 
O, Mg_Five Al_Two (OH)₁₄CO_Three ・ 4H_Two O, Mg_Three 
Al_Two (OH)_TenCO_Three ・ 1.7H_Two O, etc.
Can be.

These hydrotalcites are used in an amount of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the total blended rubber of the composition of the present invention. If the amount is less than this range, it is difficult to achieve both the rapid vulcanization rate and good storage stability aimed at by the present invention.

Such hydrotalcites are known as an acid acceptor which gives a halogen-containing elastomer having good water resistance (JP-A-57-151652). It is also known that when vulcanizing chlorinated polyethylene with an organic peroxide or the like, hydrotalcites are blended to improve heat resistance (JP-A-62-7754, JP-A-62-7654). -7755 publication etc.). However, by combining hydrotalcites with a specific vulcanizing agent such as a 2,3-dimercaptopyrazine derivative or a 2,3-dimercaptoquinoxaline derivative, a blend of an epichlorohydrin polymer rubber and an epoxy group-containing acrylic rubber can be obtained. There is no disclosure of improving the storage stability of the rubber vulcanizing composition.

In the vulcanizing composition of the present invention, a metal compound serving as an acid acceptor may be further used from the viewpoint of adjusting the vulcanization rate and the thermal stability of the vulcanized product. These compounds include oxides, hydroxides, carbonates, carboxylates, silicates, borates, phosphites of Group II metals of the Periodic Table,
Group A metal oxides, basic carbonates, basic carboxylates, basic phosphites, basic sulfites, tribasic sulfates and the like. Specific examples include magnesia, magnesium hydroxide, barium hydroxide, magnesium carbonate, barium carbonate, quicklime, slaked lime, calcium carbonate, calcium silicate, calcium stearate, zinc stearate, calcium phthalate, calcium phosphite, zinc flower,
Tin oxide, litharge, leadtan, lead white, dibasic lead phthalate,
Examples include dibasic lead carbonate, tin stearate, basic lead phosphite, basic tin phosphite, basic lead sulfite, and tribasic lead sulfate. Further, the composition of the present invention, in addition to the above, various anti-aging agents performed in the art, a filler,
Reinforcing agents, plasticizers, processing aids, pigments, flame retardants and the like can be arbitrarily compounded.

It is effective to mix known vulcanization accelerators and vulcanization retarders for the purpose of adjusting the vulcanization rate. Examples of these vulcanization accelerators include sulfur, thiuram sulfides, morpholine polysulfides, amines, weak acid salts of amines, basic silica, quaternary ammonium salts, and quaternary phosphonium salts. On the other hand, examples of the vulcanization retarder include N-cyclohexylthiophthalimide.

The composition of the composition of the present invention may be selected from any means conventionally used in the field of polymer processing,
For example, a mixing roll, a Banbury mixer, various kneaders, and the like can be used. The composition of the present invention can be usually vulcanized by heating to 100 to 200 ° C. Although the vulcanization time varies depending on the temperature, the vulcanization time is set at 0.
It usually takes place between 5 and 300 minutes. As a method of vulcanization molding, any method such as compression molding by a mold, injection molding, steam can, air bath, infrared or microwave heating can be used.

[0019]

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Examples 1 to 7 and Comparative Examples 1 to 5 The blends shown in Table 1 were kneaded with an open roll at 60 to 70 ° C, and the storage stability is shown in Table 2. Immediately after kneading, a sheet of each compound was placed in a mold.
Pressure molding was performed at 80 ° C. and 80 kg / cm ² for 15 minutes. Each of the obtained vulcanizates was subjected to a physical property test, and the results are shown in Table 3. The vulcanization curves of the blends of Examples 1, 3, and 6 and Comparative Examples 1, 2, and 3 were measured immediately after kneading using a JSR Curastometer III at an amplitude angle of 3 ° and 170 ° C. The results are shown in FIGS.

[0020]

[Table 1]

[0021]

[Table 2]

In Table 1, * 1 "Epichromer H" (trade name, manufactured by Daiso Co., Ltd., M
L _{1 + 4} 100 ° C. 50) * 2 “Epichromer C” (trade name, manufactured by Daiso Co., epichlorohydrin / ethylene oxide (50/50 molar ratio) copolymer, ML _{1 + 4} 100 ° C. 65) * 3 “Epichromer CG-104” (Trade name, Epichlorohydrin / ethylene oxide / acryl glycidyl ether (63/34/3 molar ratio) copolymer, ML _{1 + 4} 100 ° C 65, manufactured by Daiso Co., Ltd.) * 4 Ethyl acrylate / allyl glycidyl ether, 97/3 weight ratio ML _{1 + 4} 100 ° C. 60 * 5 ethyl acrylate / butyl acrylate / methoxyethyl acrylate / glycidyl methacrylate,
60/20/15/5 weight ratio ML _{1 + 4} 100 ° C. 40 * 6 “Carplex # 1120” (trade name, manufactured by Shionogi & Co., Ltd.) * 7 Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H _{2 O * 8 Mg 4.5 Al 2 (} OH) 13 CO 3 * 9 Mg 6 Al 2 (OH) 16 CO 3 · 4H 2 O * 10 1,8- diazabicyclo (5,4,0) undecene-7

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

[Table 5]

In the above tables, each example is an example in which no hydrotalcites are blended (Comparative Example 1) and an example in which no hydrotalcites is blended and a vulcanizing agent different from the present invention is used (Comparative Example 2) As shown in Table 2, it can be seen that the storage stability was greatly improved. As shown in FIGS. 1 and 2, the blending example in which the hydrotalcites were combined with a vulcanizing agent different from the present invention (Comparative Example 3) was significantly slower in the vulcanization rate than each of the examples. An example using an epichlorohydrin rubber containing no epoxy group-containing acrylic rubber (Comparative Example 4) has poor heat aging resistance, and an example (Comparative Example 5) having a blend rubber ratio outside the range of the present invention has a vulcanization rate of Due to the low speed, tensile strength and compression set are reduced, and oil resistance is also poor.

[0027]

According to the present invention, there is provided a vulcanized rubber composition comprising an epichlorohydrin polymer rubber and an epoxy-based acrylic rubber, which has excellent vulcanization speed, improved vulcanization properties and long-term storage stability. Things are obtained.

[Brief description of the drawings]

FIG. 1 is a vulcanization curve immediately after kneading of a composition in Examples 1, 3, and 6.

FIG. 2 is a vulcanization curve immediately after kneading of compositions in Comparative Examples 1 to 3.

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C08K 5:46) C08K 5:46) (56) References JP-A-58-111843 (JP, A) JP-A-57-151652 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 71/03 C08L 33/14-33/16 C08K 3/26 C08K 5/46-5/47 CA (STN)

Claims (5)

(57) [Claims] 1. To 100 parts by weight of a blend rubber comprising (a) 40 to 99% by weight of an epichlorohydrin polymer rubber and (b) 1 to 60% by weight of an epoxy group-containing acrylic rubber, (c) the following general formula 2,3-dimercaptopyrazine derivative represented by I) or 2,3-dimercaptoquinoxaline derivative represented by the following general formula (II): 0.1 to 1
0 parts by weight and (d) hydrotalcites 0.1 to 20
A composition for vulcanizing a blended rubber, comprising parts by weight. Embedded image (However, R ¹ R ² R ³ R ⁴ R ⁵ and R ⁶ may be the same or different and represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) 2. The 2,3-dimercaptopyrazine derivative is pyrazine-2,3-dithiocarbonate, 5-ethylpyrazine-2,3-dithiocarbonate, 5,6-dimethylpyrazine-2,3-dithiocarbonate, The vulcanizing composition according to claim 1, which is at least one kind of -n-butylpyrazine-2,3-dithiocarbonate. 3. The method of claim 2, wherein the 2,3-dimercaptoquinoxaline derivative is quinoxaline-2,3-dithiocarbonate,
Methylquinoxaline-2,3-dithiocarbonate, 6
The vulcanizing composition according to claim 1, which is at least one of -isopropylquinoxaline-2,3-dithiocarbonate and 5,8-dimethylquinoxaline-2,3-dithiocarbonate. 4. The vulcanizing composition according to claim 1, wherein the 2,3-dimercaptoquinoxaline derivative is 6-methylquinoxaline-2,3-dithiocarbonate. 5. The hydrotalcites represented by the following general formula (II)
I) Mg _x Al _y (OH) _{2x + 3y-2} CO ₃ .wH ₂ O (III) (where x is 1 to 10, y is 1 to 5, w is a real number)
The vulcanizing composition according to any one of claims 1 to 4, which is represented by the following formula: