JP3391174B2 - Acrylic rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acrylic rubber composition. More specifically, it relates to an acrylic rubber composition that is preferably used as an injection molding material or the like.

[0002]

2. Description of the Related Art Acrylic rubber used as a vulcanization molding material for various seal products such as oil seals, gaskets, O-rings, hoses, and other industrial rubber products generally has a slow vulcanization rate. For this reason, compression vulcanization molding is mainly used, and in addition, secondary vulcanization is required after molding in order to obtain predetermined vulcanization properties.

Particularly, in the case of an acrylic rubber containing an active chlorine group as a crosslinkable group, the tendency that the vulcanization rate is slow is remarkable, and higher fatty acid metal salts (fatty acid metal soap) and sulfur or Even when a vulcanization system comprising a sulfur donor is used, the vulcanization rate is slow.
58-180539, 61-78858, and 61-103957.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an acrylic rubber composition containing an active chlorine group-containing acrylic rubber, a filler, a higher fatty acid metal salt and sulfur or a sulfur donor, which is vulcanized. It is an object of the present invention to provide a material that has a high speed and is therefore preferably used as an injection molding material.

[0005]

The object of the present invention is as follows.
In the above acrylic rubber composition, the pH of the filler is 7
It is achieved by using ~ 10.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the active chlorine group-containing acrylic rubber, at least one kind of alkyl acrylate, alkoxyalkyl acrylate, alkylthioalkyl acrylate, cyanoalkyl acrylate, etc. is used as a main component (about 60 to 99.8% by weight), 2-chloroethyl <br/> Biniruete Le, vinyl-chloroacetate, allyl chloroacetate or glycidyl acrylate, glycidyl methacrylate, about 0.1 to 10 wt, and more addition reaction product of a glycidyl compound and monochloroacetic acid, such as allyl glycidyl ester %, Preferably about 1 to 5% by weight, a copolymer is used, and other vinyl compounds may be copolymerized within the range of 30% by weight or less.

As the filler, one having a pH of 7 to 10 (measured as the pH of a 10% aqueous suspension) is used.
Carbon black such as carbon black, FT carbon black or aluminum silicate, calcium silicate,
At least one kind of white carbon such as magnesium silicate is about 3 per 100 parts by weight of acrylic rubber containing active chlorine group.
It is used in a proportion of 0 to 150 parts by weight, preferably about 50 to 120 parts by weight.

If a filler having a pH lower than this is used, the vulcanization rate becomes slower, while if a pH higher than this is used, the vulcanization rate becomes too fast, resulting in scorch, which is impractical. Become. Comparative Examples of JP-A 61-78858 and Comparative Examples 1 and 3 of 61-103957.
Describes the vulcanization conditions of an acrylic rubber composition containing an active chlorine group-containing acrylic rubber, HAF carbon black, a higher fatty acid metal salt and sulfur.
After press vulcanization at 8 ° C for 8 minutes, it is carried out by secondary vulcanization at 150 ° C for 15 hours, and when HAF carbon black having a pH of 6 is used as a filler, it generally takes about 30 to 60 seconds. It has been shown to be unsuitable for injection molding, which requires only a short molding time.

As the higher fatty acid metal salt, an alkali metal salt or an alkaline earth metal salt of a fatty acid having an alkyl group or an alkenyl group having 8 to 18 carbon atoms, for example, sodium stearate, potassium stearate, potassium myristate, palmitic acid. Sodium, calcium stearate, magnesium stearate, sodium oleate, potassium oleate, barium oleate, etc., in an amount of about 0.5 to 10 parts by weight, preferably about 1.5 to 8 parts by weight per 100 parts by weight of the active chlorine group-containing acrylic rubber. Used in.

Sulfur or sulfur donors such as 2,4,6-
Trimercaptotriazine, polymer sulfur, etc., is about 0.2 to 5 parts by weight per 100 parts by weight of the active chlorine group-containing acrylic rubber,
It is preferably used in a proportion of about 0.4 to 3 parts by weight.

For the preparation of a composition containing the above-mentioned respective components as essential components, a processing aid, a plasticizer, an antioxidant and various other compounding agents (provided that the pH is 5 or less or 11 or more are added, if necessary. Should be avoided) and kneaded using a Banbury mixer, intermix, kneader, open roll, etc., and the kneaded product is processed into a dough using an extruder, roll, burwell, shirring, etc. After vulcanization molding. Vulcanization molding can be carried out by compression molding as is generally done, but
It also enables injection molding performed in a molding time of about 60 seconds.

[0012]

EFFECTS OF THE INVENTION By using a filler having a pH of 7 to 10,
Since injection molding that requires rapid vulcanization becomes possible, productivity can be improved and production cost can be reduced. Moreover, the vulcanized and injection-molded product has the same vulcanized physical properties as the compression-molded product.

[0013]

EXAMPLES The present invention will now be described with reference to examples.

Example 1 100 parts by weight of active chlorine group-containing acrylic rubber (Nippon Mectron product Knoxtite PA402S) MT carbon black (ASTM N990, pH9) 100 〃 silica (Celite 240, pH9.5) 20 〃 4,4'- (α, α-Dimethylbenzyl) diphenylamine 2 〃 Anti-aging agent (Santeite R, Seiko Chemicals) 1 〃 Sulfur 0.5 〃 Sodium stearate 4 〃 Potassium stearate 1.5 〃 Mix the above ingredients with 3L kneader, and mix 10 Fabricate into sheet form with inch mill roll and injection pressure 1200kg
Injection molding was performed under vulcanization conditions of / cm ² , temperature of 200 ° C., and time of 40 seconds to form a 120 × 40 × 2 mm vulcanized rubber sheet.

Comparative Example 1 100 parts by weight of acrylic rubber containing active chlorine group (Noxtite PA402S) HAF carbon black (ASTM N330, pH6) 60 〃 silica 20 〃 (Japan Aerosil product Aerosil # 200, pH4) 4,4 '-( α, α-Dimethylbenzyl) diphenylamine 2 〃 Antiaging agent (Santite R) 1 〃 Sulfur 0.5 〃 Sodium stearate 4 〃 Potassium stearate 1.5 〃 Preparation and injection of the same composition as in Example 1 Molding was done.

Example 2 100 parts by weight of active chlorine group-containing acrylic rubber (Nippon Mectron product Knoxtite A1095) FT carbon black (ASTM N800, pH8) 80 〃 silica-aluminum silicate mixture 10 〃 (Hofmann mineral product Actidyl VM, pH7) ) 2,2,4-Trimethyl-1,3-dihydroquinoline 2 〃 Anti-aging agent (Ouchi Emerging Chemicals Sannok) 1 〃 Stearic acid 1 〃 Polymeric sulfur (Toyo Chemicals Bulker) 1 〃 Potassium stearate 2 〃 Sodium palmitate 5 〃 Mix each of the above components with a 10 L Banbury mixer and mix
Fabricate into a sheet with a 16-inch mill roll, and injection-mold it under injection pressure of 1200 kg / cm ² , temperature of 220 ° C and vulcanization condition of time of 60 seconds to form a vulcanized rubber sheet of 120 × 40 × 2 mm. did.

Comparative Example 2 100 parts by weight of acrylic rubber containing active chlorine group (Knoxtite A1095) FEF carbon black (ASTM N550, pH 6.5) 50 〃 silica-aluminum silicate mixture (Actidyl VM, pH 7) 10 〃 dibasic Lead phosphite 5 〃 Hexamethylenediamine carbamate 2 〃 2,2,4-Trimethyl-1,3-dihydroquinoline 2 〃 Anti-aging agent (Sannoc) 1 〃 Stearic acid 1 〃 Using the above components, Example 2 and A similar composition was prepared and injection molded.

Example 3 100 parts by weight of active chlorine group-containing acrylic rubber (Nippon Mectron product Knoxtite PA212) MT carbon black (ASTM N990, pH9) 80 〃 Silica (Shionogi Pharmaceutical product Carplex # 100, pH10) 15 〃 4, 4 '-(α, α-Dimethylbenzyl) diphenylamine 1 〃 Antiaging agent (Sannoc) 2 〃 2,4,6-Trimercaptotriazine 1 〃 Sodium palmitate 4 〃 Using each of the above components, as in Example 1 After processing the dough,
Injection molding was performed under vulcanization conditions of an injection pressure of 1200 kg / cm ² , a temperature of 210 ° C., and a time of 60 seconds to form a 120 × 40 × 2 mm vulcanized rubber sheet.

Comparative Example 3 100 parts by weight of acrylic rubber containing active chlorine group (Noxtite PA212) FEF carbon black (ASTM N550, pH 6.5) 60 〃 dibasic lead phosphite 6 〃 hexamethylene diamine carbamate 2 〃 4, 4 '-(α, α-Dimethylbenzyl) diphenylamine 1 〃 Antiaging agent (SANNOC) 2 〃 Using the above components, the same composition as in Example 3 was prepared and injection-molded.

In the case of each of the above examples, the slab sheet molded under the respective injection molding conditions was subjected to JIS
Vulcanization physical properties and compression set (150 ℃, 70
When the time) was measured, as shown in the table below, there was almost no difference compared with the case where secondary vulcanization (150 ° C., 10 hours) was performed.

Table Example 1 Example 2 Measurement item Before secondary vulcanization After secondary vulcanization Before secondary vulcanization After secondary vulcanization Hardness (JIS A) 75 77 68 71 100% modulus (kgf / cm ² ) 70 72 60 65 Tensile strength (kgf / cm ² ) 120 125 105 113 Elongation at break (%) 150 140 130 120 Compression set (%) 48 40 45 40 Example 3 Measurement items Secondary vulcanization Secondary vulcanization Post-vulcanization hardness (JIS A) 70 72 100% Modulus (kgf / cm ² ) 62 65 Tensile strength (kgf / cm ² ) 118 122 Elongation at break (%) 160 150 Compression set (%) 50 44

On the other hand, in the case of each of the comparative examples, the vulcanization rate was slow, and the rubber sheet foamed under each injection molding condition and could not be molded in the unvulcanized state. In addition, in Example 1, even when the higher fatty acid metal salt was not used, similar results were obtained.

Claims (2)

(57) [Claims] 1. Acrylic rubber containing active chlorine group, pH of 7-1
An acrylic rubber composition comprising 0 filler, a higher fatty acid metal salt and sulfur or a sulfur donor. 2. Use as an injection molding material.
The acrylic rubber composition described.