JP3156403B2 - Method for producing acrylic copolymer rubber and composition thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic copolymer rubber and a composition thereof. More specifically, the present invention relates to a method for producing an acrylic copolymer rubber having excellent oil resistance, cold resistance and heat resistance, and a composition thereof.

[0002]

2. Description of the Related Art Conventionally, various synthetic rubbers have been used as rubbers for industrial materials mainly for automobile parts. However, high performance that is not satisfied at the level of cold resistance and heat resistance has been required.

[0003] Such demands are generally dealt with by changing the polymer composition, changing the type and amount of the compounding agent, and the like, but in these ways, oil resistance, cold resistance and heat resistance are all reduced. It is difficult to improve. In the case of acrylic copolymer rubber, a method for improving cold resistance by using 2-methoxyethyl acrylate as a main component monomer is known (Japanese Rubber Association Vol. 53, No. 6, No. 367, 1980), in which case the oil resistance and heat resistance are rather deteriorated.

Therefore, as an acrylic copolymer rubber having improved cold resistance without impairing other physical properties such as oil resistance and heat resistance as much as possible, ethyl acrylate is represented by the general formula CH ₂ = CR ¹ COO [(CH ₂ ) Acrylic copolymer rubber obtained by copolymerizing a caprolactone-added (meth) acrylate represented by ₅ COO] nR ² and a monomer having a crosslinkable group has been proposed (JP-A-63-264,612,
No. 63-268,717), it is pointed out that the compression set characteristics at low temperatures do not show practically sufficient low temperature characteristics.

[0005] Against the background of the problems of the prior art, an acrylic copolymer rubber capable of simultaneously obtaining oil resistance, cold resistance, and heat resistance and obtaining a rubber composition having improved compression set at low temperatures. Was then proposed (JP-A-2-209,907
Gazette, and 3-160,008 gazette).

The acrylic copolymer rubber proposed here is obtained by converting a (meth) acrylic ester represented by the general formula CH ₂ CRCR ¹ COO (R ² COO) nR ³ into an alkyl
(Meth) acrylate and / or alkoxyalkyl
It is obtained by copolymerizing with (meth) acrylate and a monomer having a crosslinkable group, and achieves the desired modification as described above, but is inferior in scorch resistance, and therefore practical. Raises new issues.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an acrylic copolymer rubber having not only a good balance of oil resistance, cold resistance and heat resistance but also having no problem in scorch resistance. It is to provide a manufacturing method.

Another object of the present invention is to provide a composition obtained by adding such an acrylic copolymer rubber to a conventional acrylic copolymer rubber and modifying the same.

[0009]

[Means for Solving the Problems] The production of acrylic copolymer rubber to achieve these objects is as follows: (a) CH ₂ = CR ₁ COOR ₂ O (COCmH ₂ mO) nCOR ₃ (where R ₁ is hydrogen An atom or a methyl group, R ₂ is a lower alkylene group, R ₃ is a lower alkyl group, m
Is an integer of 2 to 20 and n is an integer of 1 to 20) (meth) acrylate 5-94.9% by weight ,
(b) at least one of alkyl (meth) acrylate and alkoxyalkyl (meth) acrylate 94.9 to 5 weight
% And (c) 0.1 to 10% by weight of a crosslinking group-containing monomer.

(Meth) acrylic acid represented by the above general formula
As the ester (a), for example, the following are used:
It is. These (meth) acrylates are ε-cap
Reaction of Lolactone with Hydroxyalkyl Acrylate
After that, the terminal hydroxyl group is acylated to obtain
Can be CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FiveO] COCH_Three  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FiveO] COC_TwoH_Five  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FiveO]_TwoCOCH_Three  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FiveO]_TwoCOC_TwoH_Five  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FiveO]_ThreeCOCH_Three  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FiveO]_ThreeCOC_TwoH_Five  CH_Two= C (CH_Three) COOC_TwoH_FourO [CO (CH_Two)_FiveO] COCH_Three  CH_Two= C (CH_Three) COOC_TwoH_FourO [CO (CH_Two)_FiveO] COC_TwoH_Five  CH_Two= C (CH_Three) COOC_TwoH_FourO [CO (CH_Two)_FiveO]_TwoCOCH_Three  CH_Two= C (CH_Three) COOC_TwoH_FourO [CO (CH_Two)_FiveO]_TwoCOC_TwoH_Five  CH_Two= C (CH_Three) COOC_TwoH_FourO [CO (CH_Two)_FiveO]_ThreeCOCH_Three  CH_Two= C (CH_Three) COOC_TwoH_FourO [CO (CH_Two)_FiveO]_ThreeCOC_TwoH_Five  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_ThreeO] COCH_Three  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_ThreeO] COC_TwoH_Five  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FourO] COCH_Three  CH_Two= CHCOOC_TwoH_FourO [CO (CH_Two)_FourO] COC_TwoH_Five  CH_Two= CHCOOC_ThreeH₆O [CO (CH_Two)_ThreeO] COCH_Three  CH_Two= CHCOOC_ThreeH₆O [CO (CH_Two)_ThreeO] COC_TwoH_Five  CH_Two= CHCOOC_ThreeH₆O [CO (CH_Two)_FourO] COCH_Three  CH_Two= CHCOOC_ThreeH₆O [CO (CH_Two)_FourO] COC_TwoH_Five  CH_Two= CHCOOC_ThreeH₆O [CO (CH_Two)_FiveO] COCH_Three  CH_Two= CHCOOC_ThreeH₆O [CO (CH_Two)_FiveO] COC_TwoH_Five  CH_Two= CHCOOC_FourH₈O [CO (CH_Two)_ThreeO] COCH_Three  CH_Two= CHCOOC_FourH₈O [CO (CH_Two)_ThreeO] COC_TwoH_Five  CH_Two= CHCOOC_FourH₈O [CO (CH_Two)_FourO] COCH_Three  CH_Two= CHCOOC_FourH₈O [CO (CH_Two)_FourO] COC_TwoH_Five  CH_Two= CHCOOC_FourH₈O [CO (CH_Two)_FiveO] COCH_Three  CH_Two= CHCOOC_FourH₈O [CO (CH_Two)_FiveO] COC_TwoH_Five

The copolymerization ratio of these (meth) acrylates is 5 to 94.9% by weight , preferably 5 to 50% by weight .

As the alkyl (meth) acrylate of the component (b), an alkyl (meth) acrylate having an alkyl group having 1 to 8, preferably 1 to 4 carbon atoms, preferably an alkyl acrylate, is used.
As the (meth) acrylate, alkoxyalkyl (meth) acrylate having 1 to 10 carbon atoms, preferably 1 to 3 alkoxy groups and 1 to 10 carbon atoms, preferably 1 to 3 alkylene groups, preferably alkoxyalkyl acrylate For example, methoxymethyl acrylate, ethoxymethyl acrylate, methoxyethyl acrylate,
Ethoxyethyl acrylate and the like are used, both of which are 94.9 to 5% by weight in total , preferably 94.9 to 50% by weight.
% .

The crosslinkable group-containing monomer (c) includes a reactive halogen-containing vinyl monomer, an epoxy group-containing vinyl monomer, a carboxyl group-containing vinyl monomer, and a hydroxyl group-containing vinyl monomer. Isomer, an amide group-containing vinyl monomer, a diene-based monomer, or the like is preferably used.Preferably, a reactive halogen-containing vinyl monomer such as vinyl monochloroacetate or 2-chloroethyl vinyl ether is used in an amount of about 0.1 to 10% by weight, Preferably, they are copolymerized in such a proportion that they occupy about 0.5 to 5% by weight.

In addition to these comonomer components, about 30% by weight
In the following proportions, other monomers having copolymerizability with these,
For example, ethylene, propylene, vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, styrene, ethyl vinyl ether, butyl vinyl ether and the like can be further copolymerized.

The copolymerization reaction is carried out by any polymerization method such as emulsion polymerization, suspension polymerization, solution polymerization and bulk polymerization in the presence of a commonly used radical initiator. The radical initiator can also be used as a redox system. In the case of emulsion polymerization, which is a preferred polymerization method, the polymerization reaction is performed in the presence of various surfactants.

The polymerization reaction may be carried out in a batch system or in any system such as a continuous or intermittent addition system.
C., preferably at a temperature of about 2-80.degree. Separation of the copolymer after the completion of the reaction is carried out by different methods depending on the polymerization method.For example, in the case of an emulsion polymerization method or a suspension polymerization method, a coagulant such as an acid or a polyvalent metal salt is added to the reaction mixture. And the separated copolymer is subjected to washing and drying steps.

The resulting acrylic copolymer rubber is obtained as having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 5 or more, preferably 5 to 100. Those having a Mooney viscosity of less than this are inferior in tensile strength as rubber, while those having too high a Mooney viscosity are inferior in processability.

Crosslinking of the acrylic copolymer rubber is carried out by adding a crosslinking agent and other necessary compounding agents according to the type of the crosslinkable group copolymerized in the copolymer rubber, such as an open roll and a Banbury mixer. After kneading by using, the reaction is carried out according to commonly used crosslinking conditions.

The acrylic copolymer rubber is treated with (b) an alkyl (meth) acrylate and an alkoxyalkyl (meth)
A conventional acrylic copolymer rubber which is a copolymer of at least one acrylate and (c) a crosslinkable group-containing monomer,
About 95-5% by weight, preferably about 95-50% by weight in the blend
, The oil resistance and the cold resistance can be improved without deteriorating the heat resistance. Similarly, even when added to a nitrile rubber, a hydrogenated nitrile rubber, a fluororubber, an ethylene-alkyl acrylate copolymer, an ethylene-vinyl acetate-alkyl acrylate terpolymer, the modification thereof can be achieved. .

[0020]

According to the present invention, at least one of (b) alkyl (meth) acrylate and alkoxyalkyl (meth) acrylate
In the seed and (c) a copolymer of a crosslinkable group-containing monomer, further represented by the general formula (meth) acrylic acid ester (a)
By copolymerizing, an acrylic copolymer rubber having not only a good balance in oil resistance, cold resistance and heat resistance but also no problem in scorch resistance can be obtained. The obtained acrylic copolymer rubber is oil-sealed.
It is suitably used as a molding material for tools, O-rings, packings, gaskets, hoses and the like.

[0021]

Next, the present invention will be described with reference to examples.

Examples 1 to 6 and Comparative Examples 1 to 3 In a separable flask equipped with a thermometer, a stirrer, a nitrogen inlet tube and a decompression device, 150 parts of water (weight, the same applies hereinafter), 0.1 part of sodium sulfate, 5.5 parts of sodium lauryl sulfate and 100 parts of the monomer mixture shown in the following Table 1 were charged and oxygen in the system was sufficiently removed while repeating degassing and nitrogen substitution, and then 0.01 parts of sodium hydrosulfite and sodium formaldehyde sulfoxylate were added. 0.002 parts and 0.005 parts of tertiary butyl hydroperoxide were added, and the polymerization reaction was started at room temperature, and the reaction was continued for 6 hours so that the polymerization conversion was in the range of 95 to 99%. Was salted out with an aqueous sodium chloride solution, washed with water and dried to obtain a copolymer. Acrylate A: CH ₂ CHCHCOOC ₂ H ₄ O [CO (CH ₂ ) ₅ O] mCOCH ₃ (m = average
1.11) Acrylic ester B: CH ₂ = CHCOOC ₂ H ₄ O [CO (CH ₂ ) ₅ O] mCOCH ₃ (m = average
2.11) Acrylic ester C: CH ₂ CHCHCOOCH ₂ CH (CH ₃ ) O [CO (CH ₂ ) ₅ O] mCOCH ₃ (m = average
1.21) Methacrylate D: CH ₂ CC (CH ₃ ) COOC ₂ H ₄ O [CO (CH ₂ ) ₅ O] mCOCH ₃ (m = average
2.11) Acrylic ester E: CH ₂ CHCHCOO [(CH ₂ ) ₅ CO] mOC ₂ H ₄ OCH ₃ (m = average
1.32) (Margin) Table 1 Example Comparative Example 1 2 3 4 5 6 1 2 3 [monomer; part] n-butyl acrylate 40.0 40.0 40.0 40.0 40.0 40.0 45.0 70.5 40.0 2-methoxyethyl acrylate 47.5 27.5 47.5 27.5 42.5 37.5 52.5 27.0 42.5 Monovinyl acetate 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Acrylic ester A 10.0 30.0 Acrylic ester B 10.0 30.0 Acrylic ester C 15.0 Methacrylic ester D 20.0 Acrylic ester E 15.0 Polymerized rubber] Mooney viscosity (100 ° C, pts) 32 9 16 7 23 22.5 29 26 16

The acrylic copolymer rubber obtained in each of the above Examples and Comparative Examples was mixed with the following various additives and kneaded with an open roll, and the obtained composition was press-vulcanized at 180 ° C. for 8 minutes. And 2 in a oven at 175 ° C for 4 hours
Next vulcanization was performed. Acrylic copolymer rubber 100 parts by weight Stearic acid 1 4,4'-bis (α, α-dimethylbenzyl) diphenylamine 2 HAF carbon black 60 Sodium stearate 3 Potassium stearate 0.25 Sulfur 0.3

The obtained vulcanized product was subjected to oil resistance (volume change after immersion in JIS No. 3 oil at 150 ° C. for 70 hours), cold resistance (TR test) and heat resistance according to JIS K-6301. (175 ° C, 70
Change in hardness after heating over time) was measured. The results obtained are shown in the following Table 2 together with the Mooney scorch (125 ° C.) of the composition measured according to JIS K-6300. Table 2 Example Comparison Example 1 2 3 4 5 6 6 1 2 3 [Mooney scorch] MLmin (pts) 62 54 52 48 58 49 52 45 51 t ₅ (min) 16.2 14.7 13.1 20.0 11.4 19.9 13.1 16.3 2.3 [Oil resistance] Volume change rate (%) 19.6 20.7 22.2 21.5 27.2 24.4 24.9 57.9 27.4 [Cold resistance] TR-10 (℃) -39 -41 -38 -44 -42.2 -40 -36 -40 -42.5 [Heat resistance ] Hardness change (pts) +8 +8 +9 +7 +10 +8 +8 +9 +9

From the above results, the following can be said. (1) In the conventional polymer composition (Comparative Example 1), cold resistance (TR-10)
Can be produced at most at -36 ° C., and when the copolymerization ratio of n-butyl acrylate is increased in order to increase cold resistance, oil resistance is significantly reduced (Comparative Example 2). (2) In the polymer composition described in JP-A-3-160,008 (Comparative Example 3), although oil resistance, cold resistance, and heat resistance are all satisfied, the scorch resistance is inferior, and in terms of practicality, There's a problem. (3) On the other hand, in the polymer compositions of the respective examples, not only oil resistance, cold resistance and heat resistance are excellent in a well-balanced manner, but also no concern about scorch resistance.

Examples 7 to 9 In Comparative Example 1, 30 parts by weight (Example 7), 50 parts by weight (Example 8) or 70 parts by weight (100 parts by weight) of 100 parts by weight of the acrylic copolymer rubber used therein were used. Example 9) was replaced with the acrylic copolymer rubber of Example 2, and kneading, vulcanization and measurement of the vulcanized product were performed in the same manner. The results obtained are shown in Table 3 below. Table 3 Measurement Item Example 7 Example 8 Example 9 [arm - D - - score - Chi] MLmin (pts) 46 50 52 t 5 ( min) 15.1 16.3 14.8 [Oil resistance] volume change rate (%) Tasu24.0 +22.6 +21.7 [Cold resistance] TR-10 (℃) -38 -39 -40 [Heat resistance] Hardness change (pts) +8 +9 +8

When the above results are compared with the results of Comparative Example 1, oil resistance and cold resistance are improved without deteriorating heat resistance by blending the acrylic copolymer rubber according to the present invention. I understand.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between cold resistance and oil resistance in Examples 1 to 6 and Comparative Examples 1 to 3.

FIG. 2 is a graph showing the relationship between cold resistance and oil resistance in Examples 7 to 9 and Comparative Example 1.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-135811 (JP, A) JP-A-3-160008 (JP, A) JP-A-57-185236 (JP, A) JP-A-6-1985 25360 (JP, A) JP-A-5-262831 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 220/18 C08F 220/28 C08F 299/04 C08L 33/14- 33/16 CA (STN)

Claims (3)

(57) [Claims] (A) CH ₂ CRCR ₁ COOR ₂ O (COCmH ₂ mO) nCOR ₃ (where R ₁ is a hydrogen atom or a methyl group, R ₂ is a lower alkylene group, and R ₃ is A lower alkyl group, m
Is an integer of 2 to 20 and n is an integer of 1 to 20) (meth) acrylate 5-94.9% by weight ,
(b) at least one of alkyl (meth) acrylate and alkoxyalkyl (meth) acrylate 94.9 to 5 weight
% And (c) 0.1 to 10% by weight of a crosslinkable group-containing monomer. 2. An acrylic copolymer rubber having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 5 to 100, obtained by the method according to claim 1. (B) at least one of an alkyl (meth) acrylate and an alkoxyalkyl (meth) acrylate;
Seeds and (c) a copolymer 5-95% of the crosslinkable group-containing monomer and claims 1 or 2, wherein the acrylic copolymer rubbers 95
A composition comprising 5% by weight .