JPH07107088B2 - Acrylic rubber, acrylic composition and rubber products - Google Patents

Description

TECHNICAL FIELD The present invention relates to an acrylic rubber having good heat resistance and compression set characteristics, and capable of being rapidly vulcanized, a composition thereof, and a rubber product using the same. It is a thing.

[Prior Art] Acrylic rubber is an elastomer whose main component is an acrylate ester. Since the main chain of the acrylic acid ester polymer does not have a double bond, it has been conventionally practiced to copolymerize a crosslinking monomer serving as a crosslinking point.

As the crosslinking monomer, halogen group-containing compounds such as vinyl chromium acetate, chromium ethyl vinyl ether and allyl chloroacetate, and epoxy group-containing compounds such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether are known.

However, acrylic rubber using a halogen group-containing compound as a crosslinking monomer has a drawback of corroding the mold during vulcanization. Acrylic rubber using an epoxy group-containing compound as a crosslinking monomer has a drawback that the vulcanization rate is slow and a long heat treatment (secondary vulcanization) is required after vulcanization in order to obtain optimum vulcanization physical properties.

In order to improve these drawbacks, an acrylic rubber using a diene compound such as ethylidene norbornene, dicyclopentadiene and butadiene as a cross-linking monomer (Japanese Patent Laid-Open No. 50-2565).
6 etc.), dicyclopentenyloxyethyl acrylate, 3-methyl-2-butenyl acrylate and other unsaturated carboxylic acid dicyclopentenyl group-containing esters and alkenyl esters as cross-linking monomers (JP-A-61-44909). No. 61-57843).

[Problems to be Solved by the Invention] However, an acrylic rubber using a diene compound and a dicyclopentenyl group-containing ester of an unsaturated carboxylic acid or an alkenyl ester as a crosslinking monomer is not sufficient in heat resistance and compression set characteristics. Improvements in points were desired.

[Means for Solving Problems] As a result of various investigations by the present inventors in view of the above problems, the acrylic rubber has heat resistance due to the presence of hydrogen at the allylic position of the unsaturated hydrocarbon group involved in the crosslinking reaction. And the compression set characteristics are poor, and on the contrary, a compound in which hydrogen does not exist at the allylic position of the unsaturated hydrocarbon group involved in the cross-linking reaction is used as the cross-linking monomer. The inventors have found that it is good and have completed the present invention.

70 to 99.99% by weight of at least one compound selected from (A) alkyl acrylates and alkoxyalkyl acrylates according to the present invention; (B) general formula (However, X is a hydrogen atom, COOR ⁶ (where R ⁶ is carbon number 1
~ 10 alkyl groups or C2-14 alkoxyalkyl groups) or R ¹ is a hydrogen atom or a methyl group, R ² , R ³ and R ⁴ are a hydrogen atom or a group having 1 to 10 carbon atoms in which hydrogen does not exist on the carbon adjacent to the double bond, and R ⁵ is adjacent to the double bond A group having 1 to 10 carbon atoms in which hydrogen does not exist in carbon, Or -O-, and n represents 1 or 0), and 0.01 to 10% by weight of at least one compound represented by the formula (C) and other vinyl, vinylidene and vinylene unsaturated compounds. By copolymerizing at least one compound consisting of 0 to 20% by weight of a monomer in the presence of a radical polymerization initiator, an acrylic rubber which has good heat resistance and compression set characteristics and can be rapidly vulcanized is obtained. To be A rubber product obtained by blending the acrylic rubber with a cross-linking agent and vulcanized is suitably used as a hose or a sealing material.

Examples of the alkyl acrylate as the component (A) in the acrylic rubber of the present invention include methyl acrylate,
There are ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, cyanoethyl acrylate, and the like, and examples of the acrylic acid alkoxyalkyl ester include methoxyethyl acrylate. , Ethoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate, etc., and one or more of these can be used. (A)
The content of the component is 70 to 99.99% by weight, preferably 80 to 99.98
%, More preferably 85 to 99.9% by weight.
If the amount of component (A) is less than 70% by weight, the resulting acrylic rubber will become hard, which is not preferable. On the other hand, if it exceeds 99.99% by weight, the tensile strength of the resulting acrylic rubber is poor, which is not preferable. The component (B) is a compound represented by the following general formula in which hydrogen does not exist at the acrylic position of the unsaturated hydrocarbon group involved in the crosslinking reaction.

(However, X is a hydrogen atom, COOR ⁶ (where R ⁶ is carbon number 1
~ 10 alkyl group or C2-14 alkyloxyalkyl group) or R ¹ is a hydrogen atom or a methyl group, R ² , R ³ and R ⁴ are a hydrogen atom or a group having 1 to 10 carbon atoms in which hydrogen does not exist on the carbon adjacent to the double bond, and R ⁵ is adjacent to the double bond A group having 1 to 10 carbon atoms in which hydrogen does not exist in carbon, Y is Alternatively, —O—, and n represents 1 or 0) R ² and R ³ are preferably hydrogen atoms.

Further, R ² , R ³ and R ⁴ are hydrogen atoms or hydrocarbon groups having 3 to 10 carbon atoms in which hydrogen does not exist in the carbon adjacent to the double bond, and R ⁵ has hydrogen in the carbon adjacent to the double bond. No carbon number 3
Ten hydrocarbon groups are preferred. ) Specific compounds include, for example, vinyl methacrylate,
Vinyl acrylate, 1,1-dimethylpropenyl methacrylate, 1,1-dimethylpropenyl acrylate, 3,3-dimethylbutenyl methacrylate, 3,3-dimethylbutenyl acrylate, divinyl itaconate, divinyl maleate,
Divinyl fumarate, vinyl 1,1-dimethylpropenyl ether, vinyl 3,3-dimethylbutenyl ether, 1-
There are acryloyloxy-1-phenylethene, 1-acryloyloxy-2-phenylethene, 1-methacryloyloxy-1-phenylethene, 1-methacryloyloxy-2-phenylethene and the like, and particularly vinyl methacrylate and vinyl acrylate are preferable. These may be used alone or in combination of two or more. The content of the component (B) is 0.01 to 10% by weight, more preferably 0.02 to 5 and even more preferably 0.1 to 5% by weight. If the amount of the component (B) exceeds 10% by weight, the elongation will decrease. Also 0.01% by weight
If it is less than 100%, the resulting acrylic rubber has poor tensile strength.

Specific compounds of the component (C) include, for example, styrene, vinyltoluene, α-methylstyrene, vinylnaphthalene, styrene halide, acrylonitrile, methacrylonitrile, acrylamide, N-methylolacrylamide, vinyl acetate, vinyl chloride, chloride. Acrylic esters of aromatic and alicyclic alcohols such as vinylidene, divinylbenzene and cyclohexyl acrylate, benzyl acrylate, ethylene glycol dimethacrylate, and methacrylic acid, itaconic acid,
Examples include esters of unsaturated carboxylic acids such as fumaric acid and maleic acid with lower saturated alcohols. In addition, (C)
The components are used as needed, and it is suitable that the amount of the components does not exceed 20% by weight.

As the radical polymerization initiator used in the present invention, any radical-generating initiator can be used, but specific examples thereof include potassium persulfate, p-menthane hydroperoxide, methyl isobutyl ketone peroxide and the like. Examples thereof include oxides and azo compounds such as azobisisobutyronitrile. These radical polymerization initiators are used in an amount of 0.001 to 1.0% by weight based on the monomer mixture.

In the present invention, the polymerization reaction can be carried out by ordinary suspension polymerization, emulsion polymerization or the like. As the emulsifier in the emulsion polymerization method, any substance can be used as long as it can emulsify and disperse the monomer mixture, and for example, salts of alkyl sulfate, alkyl aryl sulfonate, and higher fatty acid can be used. Moreover, the reaction temperature is 0 to 80 ° C.
And the reaction time is about 0.01 to 30 hours.

The acrylic rubber of the present invention can be further improved in heat resistance and compression set characteristics by blending a crosslinking agent and a crosslinking aid as necessary.

The cross-linking agent is not particularly limited as long as it is a cross-linking agent capable of cross-linking a polymer compound having a double bond in the molecule, and examples thereof include sulfur, organic sulfur-containing compounds, and organic peroxides.
Examples thereof include resins, quinone derivatives, polyhalides, bis (dioxotriazoline) derivatives, aldehydes, epoxy compounds, amine-borane complexes and dipolar compounds.

Among these crosslinking agents, sulfur, organic sulfur-containing compounds and organic peroxides are preferable, and organic peroxides are more preferable.

The organic sulfur-containing compound is a compound that releases active sulfur by thermal dissociation, and examples thereof include tetramethylthiuram disulfide and 4,4'-dithiomorpholine which are thiuram accelerators.

Examples of the organic peroxide include dicumyl peroxide,
1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis (t-butylperoxy-iso
-Propyl) benzene, 2,5-dimethyl-2,5-di (t-
Butyl peroxy) hexane etc. are mentioned.

Examples of the resin include polymethylol and phenol resin.

Examples of quinones include p-quinone, p-quinone derivatives such as tetrachlorobenzoquinone, p-quinone oxime, p-quinone.
Examples thereof include p-quinone oxime derivatives such as quinone oxime dibenzoate.

Examples of the polyhalogen compound include trichloromelamine, hexachlorocyclopentadiene, octachlorocyclopentadiene, trichloromethanesulfochloride, benzotrichloride and the like.

Examples of the bis (dioxotriazoline) derivative include 4-phenyl-1,2,4-triazoline-3,5-dione and bis- (p
-3,5-dioxo-1,2,4-triazolin-4-yl-phenyl) methane and the like can be mentioned.

Examples of the aldehyde include paraformaldehyde and polyoxymethylene.

Examples of epoxy compounds include chlorobisphenolic epoxy compounds.

Examples of the amine-borane complex include a combination of a boron halide derivative such as triethylamine-chloroborane and triethylenediamine-bischloroborane and an amine.

Examples of the dipolar compound include dinitrone, dinitrile oxide, dinitrileimine, disidnone, and thionylparaphenylenediamine.

These cross-linking agents shorten the cross-linking time, lower the cross-linking temperature,
Crosslinking aids can be added to achieve improved performance of the crosslinked product.

For example, when sulfur is used as a cross-linking agent, thiazoles such as mercaptobenzothiazole, thiurams such as tetramethylthiuram disulfide, guanidines such as diphenylguanidine, dithiocarbamate salts such as zinc dimethyldithiocarbamate, etc. It can be effectively used as an agent.

When using an organic peroxide as a crosslinking agent, triallyl isocyanurate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate,
N, N'-methylenebisacrylamide, N, N'-m-phenylenedimaleimide and the like can be effectively used as a crosslinking aid.

When using resin as a cross-linking agent, tin chloride (SnCl
₂ · 2H ₂ O), ferric (FeCl ₃ · 6H ₂ O chloride) such as zinc chloride is used as a crosslinking agent.

When a polyhalide is used as a crosslinking agent, a halogen acceptor such as a metal oxide or triethanolamine is used as a crosslinking aid.

The amount of the crosslinking agent used is usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the acrylic rubber of the present invention.

The amount of the crosslinking aid used is 0 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the acrylic rubber.

It is also possible to blend a polymer which can be cross-linked with these cross-linking agents with the acrylic rubber of the present invention depending on the purpose. As such a polymer, for example, ethylene propylene rubber, acrylonitrile butadiene rubber, epichlorohydrin rubber, isoprene rubber,
Natural rubber, styrene butadiene rubber, butadiene rubber,
Examples thereof include fluororubber, chloroprene rubber, acrylic rubbers other than the acrylic rubber of the present invention.

The acrylic rubber of the present invention may be compounded with a compounding agent such as a filler, a reinforcing agent, an antiaging agent, a stabilizer, a plasticizer and a processing aid, if necessary.

Carbon black and white filler can be preferably used as the filler. Various carbon blacks having different physical and scientific properties can be used. White fillers include clay, talc, calcium carbonate, silica,
Any of magnesium carbonate and the like can be used.

An antioxidant can be added to further improve the heat resistance. As the antiaging agent, various types such as phenol type and amine type can be used. 2,2'-Methylenebis (4-methyl-6-
t-butylphenol), as a typical example of an amine-based compound,
4 '-(α, α-dimethylbenzyl) diphenylamine.

Further, a processing aid can be used in order to improve the workability in Banbury and rolls. Higher fatty acids, higher fatty acid salts and various esters of higher fatty acids are mentioned as processing aids. In particular, stearic acid is preferable because it can improve the processability without lowering the physical properties.

Various rubber products can be obtained by using the acrylic rubber thus obtained.

In the case of a hose, the acrylic rubber of the present invention can be used as a single layer, or as a composite hose used as an inner tube layer or an outer tube layer, or can be used by reinforcing it with a knitting layer if necessary.

The acrylic rubber of the present invention and the rubber product using the same have the following features.

1. Excellent heat resistance.

2. Good weather resistance.

3. Good oil resistance.

4. Excellent compression set characteristics.

5. The cross-linking speed is fast and secondary vulcanization can be omitted.

(Excellent productivity).

6. Co-crosslinkable with a wide variety of other rubber types.

Therefore, the acrylic rubber of the present invention and the rubber product obtained by cross-linking the acrylic rubber do not withstand the conditions that the hose and the sealing material (including the gasket) must have: 1. Tear force due to internal pressure load and excessive tightening and are not damaged.

2. Good tightness and does not allow permeation of liquids with high vacuum, high pressure or permeability.

3.Excellent heat and cold resistance, softening and hardening deterioration at high temperature,
Does not creep and does not embrittle or store at low temperatures.

4. It has excellent weather resistance and does not deteriorate due to aging or corrosion even after long-term use.

5. It has good workability, and it has a complex shape and has a small surface roughness and a smooth surface.

Since it is excellent in compression set characteristics and heat resistance, it can be suitably used for long-life hoses and sealing materials (including gaskets) with excellent binding force. Since vulcanization can be omitted, these rubber members can be preferably manufactured with high productivity. Further, since it can be co-crosslinked with a wide range of other rubbers, it can be used as a laminate with other rubbers.

Further, since the acrylic rubber of the present invention and the rubber product obtained by crosslinking the acrylic rubber have good oil resistance and heat resistance, it is possible to improve the oil resistance and heat resistance of these rubbers or resins by mixing them with various rubbers or resins. You can At that time, it is also effective to powderize and mix the acrylic rubber.

Various rubber hose materials such as oil cooler hose, air duct hose, power steering hose, control hose, intercooler hose, torque converter hose, oil return hose, heat resistant hose, bearing seal, valve stem seal, various oil seal, O-ring In addition to sealing materials such as gaskets, packings and gaskets, various diaphragms, rubber plates, belts, oil level gauges, hose masking, coating materials such as piping heat insulation materials, rolls, etc. are specifically mentioned, especially for hoses, gaskets, etc. It is useful as a sealing material.

[Examples] Hereinafter, the contents of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.

All parts and% in the examples mean parts by weight and% by weight.

Examples 1,2,6,7, Comparative Examples 1,2,4 100 parts of the monomer mixture shown in Table-I, 4 parts of sodium lauryl sulfate and 0.2 parts of potassium persulfate were charged in an iron container in which nitrogen was replaced. Polymerization was carried out at ℃ for 15 to 20 hours, and after the polymerization was almost completed, the reaction product was taken out and steam was blown to remove unreacted monomers. The acrylic rubber latex thus obtained was added to a 0.25% calcium chloride aqueous solution to coagulate (in this case, ca. 5% calcium chloride in the rubber content was used). After drying for 4 hours, acrylic rubbers A, B, F, G, H, I and K were obtained.

To 100 parts of the acrylic rubber obtained as described above, 1.0 part of stearic acid, 1.5 parts of Perkadox 14/40 (1,3 bis (t-butylperoxy-iso-propyl) benzene manufactured by Kayaku Nouri Co., Ltd.), Balnock PM 1.5 parts (Ouchi Shinko Chemical Co., Ltd., N, N'-m-phenylene dimaleimide), carbon black (tire black H) 50 parts (manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) kneaded with rolls Acrylic rubber composition I got a thing.

Next, using this rubber composition, the vulcanization rate and the properties of the vulcanized product were measured. The results are shown in Fig. 1 and Table-II, respectively.

Examples 3 to 5 Acrylic rubbers C, D and E were obtained by using the monomer mixtures shown in Table I, polymerizing in the same manner as in Example 1, coagulating and drying.

The acrylic rubber was vulcanized using the same compounding formulation as in Example 1 except that Baltok PM was not used among the compounding agents used in Example 1, and the vulcanization speed and the properties of the vulcanized product were measured. . The results are shown in Figure-1 and Table-II.

Examples 8 and 9 and Comparative Example 5 Acrylic rubbers L, M and P were obtained by post-polymerization treatment in the same manner as in Example 1 using the monomers having the compositions shown in Table-I.

In addition to the compounding ingredients used in Example 1, non-scorch-N 0.2
Part (manufactured by Seiko Chemical Co., Ltd., N-nitrosodiphenylamine) was used to perform vulcanization in the same manner as in Example 1, and the vulcanization rate and the properties of the vulcanized product were measured. The results are shown in Table-II.

Example 10 Using a monomer having the same composition as in Example 2, 0.25 part of Permenta H (p-menthane hydroperoxide manufactured by NOF CORPORATION), 0.01 part of ferrous sulfate, and ethylenediaminetetraacetic acid were used instead of potassium persulfate. Using 0.025 part of sodium and 0.04 part of sodium formaldehyde sulfoxylate at 30 ° C
Acrylic rubber N was obtained by polymerizing for 0.5 to 10 hours. Others were the same as in Example 1. The results are shown in Table-II.

Example 11 The same procedure as in Example 10 was carried out except that 0.25 part of KD33-1 (manufactured by Kayaku Nouri Co., methyl isobutyl ketone peroxide) was used instead of Permenta H (acrylic rubber O of Table-I). It shows in Table-II.

Comparative Example 3 Acrylic rubber J was obtained by post-polymerization treatment in the same manner as in Example 1, using the monomers of the composition of Table-I. The procedure of Example 1 was repeated except that 1.5 parts of Barnock AB (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., ammonium benzoate) was used in place of Perkadox 14/40 and Barnock PM in the formulation of Example 1. The vulcanization rate and the properties of the vulcanizates were measured. The results are shown in Fig. 1 and Table-II.

Vulcanization speed: Measured with JSR Curlastometer III (measurement temperature 170 ° C) Properties of vulcanizate: Unvulcanized rubber sheet was made from acrylic rubber composition, and 170 ° C for 20 minutes using a vulcanizing press. Vulcanized If necessary, use a gear oven to add 175
Vulcanized at 4 ° C for 4 hours.

The properties of the vulcanized product were measured according to JIS K-6301.

From the results of Table-II and Fig.-1, the acrylic rubber compound produced by the production method of the present invention was vulcanized more rapidly than the conventional acrylic rubber, and the obtained vulcanized product had heat resistance and compression set characteristics. It turns out that is good.

Examples 12 to 16 and Comparative Examples 6 to 7 Acrylic rubbers B and C obtained in the same manner as in Example 1 using the acrylic rubber B obtained in Example 2 and the monomer mixture shown in Table III. 100 parts of S and T were mixed with 1.0 part of stearic acid, 50 parts of carbon black (Diablack H made by Mitsubishi Kasei Kogyo Co., Ltd.), a cross-linking agent and a cross-linking auxiliary agent shown in Table-IV by a roll to obtain an acrylic rubber composition.

Next, a tube having an outer diameter of 9.5 mm (thickness 1.0 mm) was pressed using this composition, and vulcanized at 170 ° C. for 20 minutes using a vulcanizing press device. If necessary, use a gear oven to further
It was vulcanized at 175 ° C. for 4 hours, each test piece was punched out from this vulcanized product, and various physical property tests were carried out. The results are shown in Table-V.
From the results of Table-V, it can be seen that the acrylic rubber composition of the present invention is an acrylic rubber composition having good heat resistance and compression set characteristics and capable of being rapidly crosslinked.

Examples 17 to 20 and Comparative Examples 8 to 11 Acrylic rubber compositions were obtained by kneading 50 parts of acrylic rubber B or T, the rubber and compounding agents shown in Table-VI with a roll. After vulcanization using this composition under the conditions shown in the lower part of Table-VI,
The properties of the vulcanizate were measured. The results are shown in Table-VII.

From the results of Table-VII, the blend of the acrylic rubber composition of the present invention and the polymer capable of being crosslinked with the crosslinking agent of the acrylic rubber of the present invention has excellent heat resistance and compression set characteristics as compared with the conventional acrylic rubber. You can see that

[Effect of the Invention] As is clear from the above, the crosslinked product of the acrylic rubber according to the present invention has excellent heat resistance and compression set characteristics, and the acrylic rubber of the present invention has excellent effects such as rapid crosslinking.

Taking advantage of these properties, oil cooler hose, air duct hose, power steering hose, control hose, intercooler hose, torque converter hose,
Various hose materials such as oil return hoses and heat-resistant hoses, bearing seals, valve stem seals, various oil seals, O-rings, packings, gaskets and other sealing materials, as well as various diaphragms, rubber plates, belts, oil level gauges, hose masking. It is used for coating materials such as pipe heat insulation materials and rolls.

Further, since this acrylic rubber has good oil resistance and heat resistance, by mixing it with various rubbers or resins, the oil resistance and heat resistance of these rubbers or resins can be improved. At that time, it is also effective to powderize and mix the acrylic rubber.

[Brief description of drawings]

 Figure 1 shows the vulcanization curve (measurement temperature 170 ℃)

Front Page Continuation (72) Inventor Hiroshi Ise 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Toshio Miyabayashi 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Japan Rubber Co., Ltd. (72) Inventor Koji Nobu 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) Reference JP-A-54-127495 (JP, A) JP-A-54 -127494 (JP, A) JP-A-54-127493 (JP, A)

Claims (3)

[Claims] 1. At least one compound selected from the group consisting of (A) acrylic acid alkyl ester and acrylic acid alkoxyalkyl ester, 70 to 99.99% by weight, (B) general formula (However, X is a hydrogen atom, COOR ⁶ (where R ⁶ is carbon number 1
~ 10 alkyl groups or C2-14 alkoxyalkyl groups) or R ¹ is a hydrogen atom or a methyl group, R ² , R ³ and R ⁴ are a hydrogen atom or a group having 1 to 10 carbon atoms in which hydrogen does not exist on the carbon adjacent to the double bond, and R ⁵ is adjacent to the double bond A group having 1 to 10 carbon atoms in which hydrogen does not exist in carbon, Y is Or -O-, or n represents 1 or 0), and 0.01 to 10% by weight of at least one compound represented by the formula (C) and other vinyl-based, vinylidene-based and vinylene-based unsaturated compounds. Acrylic rubber obtained by copolymerizing at least one compound of 0 to 20% by weight in the presence of a radical polymerization initiator. 2. An acrylic rubber composition comprising the acrylic rubber of claim (1) and a crosslinking agent as essential components. 3. A rubber product obtained by crosslinking the acrylic rubber composition according to claim 2.