JP2010159377A - Acrylic rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic rubber composition that does not deteriorate compression set characteristics and is inexpensive, and the acrylic rubber composition available for a sealing part, such as an O-ring, a gasket, or packing. <P>SOLUTION: The acrylic rubber composition is obtained by blending 10-100 pts.wt. of carbon black of which an amount of iodine adsorption is 15-25 mg/g and an amount of DBP oil absorption is 120-130 cm<SP>3</SP>/100g and 20-100 pts.wt. of calcium carbonate with 100 pts.wt. of an ACM polymer, and preferably 10-100 pts.wt. of MT carbon other than the carbon black is blended. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an acrylic rubber composition used as seal parts such as O-rings and gaskets and other rubber parts, and particularly relates to an acrylic rubber composition that does not deteriorate compression set characteristics and is low in cost.

  The ACM seal material has heat resistance and oil resistance next to FKM and VMQ, and has a heat resistance level of about 50 ° C. better than that of the NBR material. However, in terms of price, it is more expensive than NBR materials, and currently applicable items are limited.

  Therefore, conventionally, when designing low-priced materials, a method of reducing the hardness of the base material with a plasticizer and adding a large amount of carbon, or diatomaceous earth, aluminum silicate, calcium metasilicate, etc. is used as an extender. Is used.

  However, the above-described method has a drawback that physical properties, particularly compression set characteristics, are greatly deteriorated, and the function as a high-performance sealing material such as an O-ring or a gasket material is not sufficient.

Patent Document 1, an iodine adsorption amount 15 to 25 mg / g to ACM, by DBP oil absorption of blending carbon black is 120~130cm ³ / 100g, it is described that the compression set characteristics are improved However, when a large amount of a bulking agent such as diatomaceous earth is blended for cost reduction, there is a problem that the compression set characteristic is greatly deteriorated.

WO2007 / 145337

  Accordingly, an object of the present invention is to provide a low-cost acrylic rubber composition that does not deteriorate compression set characteristics.

  Another object of the present invention is to provide an acrylic rubber composition used as sealing parts such as O-rings, gaskets and packings.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

(Claim 1)
Respect ACM polymer 100 parts by weight, the amount of iodine adsorbed was 15 to 25 mg / g, DBP oil absorption amount blended 20 to 100 parts by weight of 10 to 100 parts by weight of calcium carbonate and carbon black as a 120~130cm ³ / 100g Acrylic rubber composition.

(Claim 2)
The acrylic rubber composition according to claim 1, wherein 10 to 100 parts by weight of MT carbon different from the carbon black is blended.

(Claim 3)
The acrylic rubber composition according to claim 1 or 2, wherein the acrylic rubber composition is used as a sealing part selected from an O-ring, a gasket or a packing.

  ADVANTAGE OF THE INVENTION According to this invention, the acrylic rubber composition excellent in the compression set characteristic at low cost can be provided.

  Furthermore, according to this invention, the acrylic rubber composition used as sealing parts, such as an O-ring, a gasket, and packing, can be provided.

  Embodiments of the present invention will be described below.

Acrylic rubber composition of the present invention, with respect to 100 parts by weight of ACM polymer, 10 to 100 parts by weight of carbon black iodine adsorption amount 15 to 25 mg / g, DBP oil absorption amount is 120~130cm ³ / 100g and carbonate It is characterized by blending 20 to 100 parts by weight of calcium.

<ACM polymer>
The main component monomer used in the ACM polymer of the present invention includes, for example, alkyl acrylate or alkoxyalkyl acrylate, butyl acrylate, and a crosslinking point monomer having a functional group.

  Examples of the alkyl acrylate include ethyl acrylate (EA).

  Examples of the alkoxyalkyl acrylate include methoxyethyl acrylate (MEA), methoxybutyl acrylate, ethoxybutyl acrylate, and the like, and preferably methoxyethyl acrylate (MEA) is used.

  Examples of the crosslinking point monomer having a functional group include monomers obtained by combining one or more functional groups composed of a carboxyl group, an epoxy group, and a chlorine group (including an active chlorine group).

Examples of the crosslinking point monomer having a carboxyl group include acrylic acid, methacrylic acid,
Examples include crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, maleic acid monoalkyl ester, fumaric acid monoalkyl ester, itaconic acid monoalkyl ester, and the like.

  Examples of the crosslinking point monomer having an epoxy group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and methallyl glycidyl ether.

  Examples of the crosslinking point monomer having a chlorine group (including an active chlorine group) include 2-chloroethyl vinyl ether, 2-chloroethyl acrylate, vinyl benzyl chloride, vinyl chloroacetate, and allyl chloroacetate.

  A preferred combination of main component monomers used in the ACM polymer of the present invention is methoxyethyl acrylate (MEA) -butyl acrylate (BA) -active chlorine group-containing crosslinking point monomer, or ethyl acrylate (EA) -acrylic acid. Examples include butyl (BA) -active chlorine group-containing crosslinking point monomers.

  The ACM polymer of the present invention can be obtained by copolymerizing a crosslinking point monomer or other copolymerizable monomer component by a known method such as emulsion polymerization, suspension polymerization, solution polymerization or bulk polymerization.

  Other monomer components used in the ACM polymer of the present invention include acrylic group, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid and other carboxyl group-containing compounds; 1,1-dihydro Perfluoroethyl (meth) acrylate, 1,1-dihydroperfluoropropyl (meth) acrylate, 1,1,5-trihydroperfluorohexyl (meth) acrylate, 1,1,2,2-tetrahydroperfluoropropyl (meth) acrylate, Fluorinated acrylic acid esters such as 1,1,7-trihydroperfluoroheptyl (meth) acrylate, 1,1-dihydroperfluorooctyl (meth) acrylate, 1,1-dihydroperfluorodecyl (meth) acrylate; 1-hydroxypropyl (Meta) ak Hydroxyl group-containing acrylic acid esters such as 2-hydroxypropyl (meth) acrylate and hydroxyethyl (meth) acrylate; tertiary amino group-containing acrylic esters such as diethylaminoethyl (meth) acrylate and dibutylaminoethyl (meth) acrylate Methacrylates such as methyl methacrylate and octyl methacrylate; alkyl vinyl ketones such as methyl vinyl ketone; vinyls and allyl ethers such as vinyl ethyl ether and allyl methyl ether; vinyl aromatics such as styrene, α-methyl styrene, chlorostyrene and vinyl toluene; Compounds; vinyl nitriles such as acrylonitrile and methacrylonitrile, etc., and other examples include ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl fluoride, fluorine And vinylidene chloride, vinyl acetate, vinyl propionate, and alkyl fumarate.

  The ACM polymer of the present invention can be obtained as a commercial product, and examples of the commercial product include “NOXTITE PA-402L” manufactured by Unimatec.

<Carbon black>
In the present invention, carbon black, iodine adsorption is 15 to 25 mg / g, the DBP oil absorption amount is 120~130cm ³ / 100g is used.

  The iodine adsorption amount is a value measured based on JIS K6221, and the DBP oil absorption is a value measured according to A method (mechanical method) of JIS K6221.

  When the amount of iodine adsorbed exceeds 25 mg / g, rubber reinforcement (tensile strength, elongation) can be obtained, but the hardness is high and the workability is slightly inferior, and compression set (also referred to as CS) tends to deteriorate. . When the iodine adsorption amount is less than 15 mg / g, the reinforcing property is weak and sufficient tensile strength cannot be obtained.

When DBP oil absorption is less than 120 cm ^3/100 g is not reinforcing is sufficient, the pressure during the seal, destruction of the sealing member is liable to occur in the compression and the like. When the DBP oil absorption exceeds 130 cm ^3/100 g, the hardness is high, the processability of the rubber is deteriorated.

  In this invention, the compounding quantity of carbon black is the range of 10-100 weight part with respect to 100 weight part of acrylic rubber polymers, Preferably it is the range of 20-90 weight part.

The carbon black of the present invention can be obtained as a commercially available product, for example, “Show Black IP200” manufactured by Showa Cabot Corporation (iodine adsorption amount 20 mg / g, DBP oil absorption amount 1).
25 ml / 100 g).

<MT carbon>
In the present invention, MT carbon of a different type (separate brand) from the above carbon black can be blended.

MT carbon that can be used in the present invention are those iodine adsorption amount 10-20 mg / g, DBP oil absorption amount is 30 to 50 cm ^3/100 g is preferable. By using this MT carbon in combination, better compression set properties can be obtained, and its blending amount is blended in the range of 10 to 100 parts by weight, preferably 20 to 100 parts by weight with respect to 100 parts by weight of the ACM polymer. It mix | blends in 80 weight part, More preferably, it mix | blends in 30-70 weight part.

  The MT carbon of the present invention can be obtained as a commercial product, and examples thereof include “Huber N-990 (iodine adsorption amount 15 mg / g, DBP oil absorption amount 43 ml / 100 g) manufactured by Huber.

<Weighting agent>
In the present invention, calcium carbonate is used. By blending calcium carbonate, an acrylic rubber composition having a good compression set can be obtained at a low price.

  The compounding amount of calcium carbonate is in the range of 20 to 100 parts by weight per 100 parts by weight of the ACM polymer, preferably in the range of 30 to 80 parts by weight, and more preferably in the range of 40 to 60 parts by weight.

  If the blending amount of calcium carbonate is less than 20 parts by weight, the product cost of the acrylic rubber composition cannot be lowered, so the effect of cost reduction cannot be obtained. If the blending amount exceeds 100 parts by weight, the compression set characteristics deteriorate. And a decrease in tensile strength.

  The calcium carbonate used for this invention can be obtained as a commercial item, for example, whiten B (made by Shiroishi Calcium Co., Ltd.) etc. are mentioned.

<Crosslinking agent and crosslinking accelerator>
The acrylic rubber composition of the present invention may be vulcanized by any vulcanization system such as triazine vulcanization or higher fatty acid metal salt / sulfur vulcanization.

  Examples of the triazine vulcanizing agent include 1,3,5-trithiocyanuric acid, 1-hexylamino-3,5-dimethylcaptotriazine, 1-diethylamino-3,5-dimethylcaptotriazine, 1-cyclohexylamino-3,5. -Dimethylcaptotriazine etc. are mentioned.

  When a trithiocyanuric acid crosslinking agent is used as the triazine vulcanizing agent, examples of the crosslinking accelerator include zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dimethyldithiocarbamate.

  In addition to sulfur, sulfur vulcanized compounds include 4,4′-dithiodimorpholine, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, 2-mercaptoimidazoline, tetramethylthiuram monosulfide, N-cyclohexyl- Sulfur donating compounds such as 2-benzothiazol sulfenamide, dibenzothiazyl disulfide, and polymer polysulfide are also used.

  When a sulfur vulcanizing compound is used as a vulcanizing agent, a higher fatty acid metal salt can be used as the crosslinking accelerator, such as sodium stearate, potassium stearate, potassium myristate, sodium palmitate, stear. Examples thereof include calcium phosphate, magnesium stearate, sodium oleate, potassium oleate, and barium oleate.

<Other ingredients>
In the acrylic rubber composition of the present invention, if necessary, processing aids such as stearic acid, palmitic acid, paraffin wax, acid acceptors such as zinc oxide and magnesium oxide, anti-aging agents, plasticizers, reinforcing materials, You may contain additives, such as a filler, a light stabilizer, a lubricant, an adhesive, a lubricant, a flame retardant, an antifungal agent, an antistatic agent, and a coloring agent.

  Moreover, you may further mix | blend rubber | gum other than acrylic rubber, an elastomer, resin, etc. with the rubber composition of this invention as needed. For example, rubber such as natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber; olefin elastomer, styrene elastomer, vinyl chloride elastomer, polyester elastomer, polyamide elastomer, polyurethane elastomer, An elastomer such as a polysiloxane elastomer; a resin such as a polyolefin resin, a polystyrene resin, a polyacrylic resin, a polyphenylene ether resin, a polyester resin, or a polycarbonate resin can be blended.

<Preparation, crosslinking and molding of rubber composition>
In the preparation of the rubber composition of the present invention, an appropriate mixing method such as kneading using an kneader such as an intermix, kneader, Banbury mixer or an open roll can be employed.

  At the time of crosslinking, the acrylic rubber composition of the present invention is heated. The heating temperature is preferably 130 to 220 ° C, more preferably 140 to 200 ° C, still more preferably 150 to 200 ° C, and the crosslinking time is preferably 30 seconds to 5 hours, more preferably 3 minutes to 60 minutes. is there.

  As a heating method, a method used for crosslinking of rubber such as press heating, steam heating, oven heating, hot air heating and the like may be appropriately selected.

  In addition, secondary crosslinking may be performed after the primary crosslinking in order to ensure crosslinking to the inside of the crosslinked product. The secondary crosslinking varies depending on the heating method, crosslinking temperature, shape, etc., but the heating temperature is preferably 150 to 250 ° C., and the heating time is preferably 0.5 hours to 24 hours. As the heating method, oven heating or the like may be selected as appropriate.

  The method for molding the rubber composition of the present invention is not particularly limited. Any method such as compression molding, injection molding, transfer molding or extrusion molding can be used.

  In the present invention, an injection molding machine, a compression molding machine, a vulcanizing press, or the like may be used, either a method of simultaneously performing molding and crosslinking, or a method of performing crosslinking after molding.

  The acrylic rubber composition of the present invention is vulcanized and molded, and can be suitably used for seal parts selected from O-rings, gaskets or packing, and other rubber parts, and other rubber parts include oil seals, valves, etc. Is preferably used.

  Hereinafter, the effect of the present invention is illustrated by examples.

Example 1
ACM polymer (Unimatec "Knoxtite PA-402L") 100 parts carbon black (Showa Cabot "Show Black IP200")
(Iodine adsorption 20 mg / g, DBP oil absorption of 125 cm ^3/100 g) 50 parts by weight of calcium carbonate (Shiraishi Calcium Co., Ltd., "Whiten B") 50 parts by weight of sulfur, 0.5 parts by weight of stearic acid Na 1.5 parts by weight

These blends (excluding the vulcanizing agent and vulcanization accelerator) were kneaded with a kneader, and then the vulcanizing agent and vulcanization accelerator were blended and kneaded with an open roll.

The rubber composition was molded by primary vulcanization at 170 ° C. for 20 minutes using a vulcanizing press and secondary vulcanization at 150 ° C. for 24 hours in a heating oven, and a vulcanized sheet of 150 mm × 150 mm × 2 mm and G25 size An O-ring having an inner diameter of 24.4 mm and a wire diameter of 3.1 mm was obtained.

The obtained vulcanized sheet was measured for normal properties and subjected to an O-ring compression set test.

  Table 1 shows the composition of the composition and the results of each evaluation.

<Evaluation method>
(Normal physical properties)
1. Rubber hardness Hs; measured with a type A durometer according to JIS K6253.
2. Tensile strength TB (MPa); compliant with JIS K6251.
3. Elongation EB (%); compliant with JIS K6251.

(Compression set CS test)
For the above-mentioned O-ring of G25 size (inner diameter 24.4 mm, wire diameter 3.1 mm), 150 ° C. × 70 hours, 150 ° C. × 140 hours, and 150 ° C. × 300 hours (in each case 25) % Compression compression set CS (%) after heat aging was evaluated.

Example 2
In Example 1, the amount of Show Black IP200 was reduced to 20 parts by weight, and 40 parts by weight of MT carbon was added for evaluation in the same manner. The results are shown in Table 1.

In Reference Example 1, without using the small black IP200 and calcium carbonate, instead of FEF carbon (manufactured by Tokai Carbon Co., iodine adsorption is 44 mg / g, DBP oil absorption amount 115cm ^3/100 g) blending 50 parts by weight ( A conventional acrylic rubber composition) was evaluated in the same manner. The results are shown in Table 1.

Comparative Example 1
In Example 1, Show Black IP200 (Carbon Black manufactured by Showa Cabot) and calcium carbonate were not used, but instead 80 parts by weight of FEF carbon and Adeka Sizer RS-107 (Asahi Denka Kogyo Co., Ltd.) as a plasticizer were 30. A part by weight was mixed and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 2
In Example 1, Show Black IP200 was replaced with FEF carbon and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 3
In Example 1, calcium carbonate was replaced with calcium metasilicate (“NYAD400” manufactured by NYCO) and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 4
In Example 1, calcium carbonate was replaced with diatomaceous earth (“Silka 6B” manufactured by Chuo Silica Co., Ltd.), and the same evaluation was performed. The results are shown in Table 1.

Comparative Example 5
In Example 1, calcium carbonate was replaced with aluminum silicate (“DIXIE PLAY” manufactured by VANDERVILT) and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 6
In Example 1, the blending amount of calcium carbonate was changed to 120 parts by weight and evaluated in the same manner. The results are shown in Table 1.

  From Table 1, in Example 1, compared with the reference example which is the mixing | blending of the conventional acrylic rubber, cost reduction was implement | achieved, maintaining substantially equivalent CS.

  Further, in Example 2, it can be seen that CS was further improved by adding MT carbon to Example 1.

  In Comparative Example 1, the cost was reduced by blending a plasticizer and blending a large amount of carbon in the reference example, which is a conventional blended acrylic rubber, but it can be seen that CS deteriorated.

  In Comparative Example 2, calcium carbonate was blended in a reference example that was blended with a conventional acrylic rubber, but it was found that sufficient CS was not obtained due to the use of FEF carbon having a high iodine adsorption amount and a low DBP oil absorption amount. .

  Comparative Examples 3 to 5 show that CS deteriorated because calcium metasilicate, diatomaceous earth, and aluminum silicate were used as the extender to be used in Example 1 without blending calcium carbonate. In particular, in Comparative Example 3 using calcium metasilicate and Comparative Example 4 using diatomaceous earth, it can be seen that the deterioration of TB is remarkable.

  In Comparative Example 6, since the amount of calcium carbonate is more than 100 parts by weight, it can be seen that compression set is deteriorated and TB is also decreased.

The acrylic rubber composition of the present invention is vulcanized and molded, and can be suitably used for seal parts selected from O-rings, gaskets or packing, and other rubber parts. Other rubber parts include oil seals, valves, etc. Is preferably used.

Claims (3)

Respect ACM polymer 100 parts by weight, the amount of iodine adsorbed was 15 to 25 mg / g, DBP oil absorption amount blended 20 to 100 parts by weight of 10 to 100 parts by weight of calcium carbonate and carbon black as a 120~130cm ³ / 100g Acrylic rubber composition.   The acrylic rubber composition according to claim 1, wherein 10 to 100 parts by weight of MT carbon different from the carbon black is blended.   The acrylic rubber composition according to claim 1 or 2, wherein the acrylic rubber composition is used as a sealing part selected from an O-ring, a gasket or a packing.