JP3314581B2 - Blended rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a blend rubber composition. More specifically, the present invention relates to a blend rubber of hydrogenated NBR and an ethylene / propylene copolymer rubber, which composition is suitably used as a sealing material molding material or the like.

[0002]

2. Description of the Related Art Hydrogenated NBR, which has good heat resistance and chemical stability, has been rapidly used in recent years as a molding material for sealing materials such as oil, LLC (long life coolant), and chlorofluorocarbon. Has begun. However, hydrogenated N
BR requires the use of a noble metal catalyst at the stage of hydrogenating NBR, and thus has a problem of high cost. Further, when compared with NBR, it is slightly inferior in cold resistance, and there is a concern that the sealability may be impaired when used in an extremely cold region of about -30 to -35 ° C or lower.

[0003] An inexpensive material that further improves the heat resistance and chemical stability of hydrogenated NBR and has excellent cold resistance is ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber, ethylene.・ Propylene-based copolymer rubber is available, but it has very poor oil resistance, which limits its use in places where engine oil, fuel oil, lubricating oil, grease, etc. may be mixed. Have.

[0004] Therefore, by blending both of them, the problems of cold resistance and cost of hydrogenated NBR and ethylene
It has been conceived to simultaneously solve the problem of oil resistance of propylene-based copolymer rubber. And, a swelling property with respect to the cooling liquid, that is, LLC, in which the blend rubber is made of polyethylene glycol is small (Japanese Patent Application Laid-Open No. 61-40342), and a seal member having a good balance between oil resistance and cold resistance can be obtained.
(Japanese Patent Publication No. 6-39544).

However, hydrogenated NBR and ethylene / propylene copolymer rubber have poor compatibility because of their greatly different polarities. If they are simply blended, they cannot be used in the pressing direction of the press after vulcanization. In the vertical direction, it was confirmed that they were aggregated in a single layer, that is, in a state in which they were not compatible with each other, and easily peeled off.

[0006] Such a phenomenon is observed when a cross section of a vulcanized sheet of a blended rubber is observed using a reflected electron image of an electron microscope, and the specific gravity difference between the hydrogenated NBR and the ethylene / propylene copolymer rubber causes The former is white, and the latter is black, which can be grasped from the dispersed state.

Further, the applicant of the present invention previously comprises a blend rubber of 65 to 85% by weight of hydrogenated NBR and 35 to 15% by weight of chlorinated ethylene / propylene copolymer rubber, and has excellent Freon resistance. Although a blend rubber composition capable of providing a seal member has been proposed (Japanese Patent Application Laid-Open No. 6-284415), in this case, the proportion of the chlorinated ethylene / propylene copolymer rubber to the hydrogenated NBR is less than this. , Hydrogenated NBR
The effect of improving the cold resistance was not so much observed, while when the proportion of the chlorinated ethylene / propylene copolymer rubber was increased beyond this range, there were problems such as mold stains. That is, in the case of such a blend system, the mixing ratio of the hydrogenated NBR and the chlorinated ethylene / propylene copolymer rubber is restricted, and the cost cannot be further reduced.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a blend rubber of hydrogenated NBR and ethylene / propylene copolymer rubber having improved compatibility, which has an excellent balance between cold resistance and oil resistance. Less mold stain during vulcanization,
In addition, it is an object of the present invention to provide a composition of the present invention which can set the mixing ratio of these two materials widely according to the purpose, and therefore can be suitably used as a sealing material molding material.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by a blend rubber composition in which about 3 to 30 parts by weight of a halogenated ethylene / propylene copolymer rubber is added per 100 parts by weight of a blend rubber of hydrogenated NBR and ethylene / propylene copolymer rubber.

The hydrogenated NBR includes a nitrile content of about 10
~ 50% of hydrogenated copolymer rubber of acrylonitrile and butadiene to reduce the amount of carbon-carbon double bonds in the molecular main chain by 10%
The following are generally used, and commercially available products such as Zetpol manufactured by Zeon Corporation can be used as they are. Hydrogenated NBR and ethylene / propylene-based copolymer rubber are about 95 to 5% by weight, preferably about 50 to 50% by weight.
It is used by blending at a ratio of 80% by weight and the latter at a ratio of about 5 to 95% by weight, preferably about 50 to 20% by weight.

The blended rubber contains a halogenated ethylene / propylene copolymer rubber, generally a chlorinated ethylene / propylene copolymer rubber, in an amount of about 3 to 30 parts by weight, preferably about 5 to 30 parts by weight, per 100 parts by weight of the blended rubber. 20 parts by weight are added. At an addition ratio below this, hydrogenated NBR
And ethylene-propylene copolymer rubber do not have a sufficient compatibilizing effect. On the other hand, if added at a higher ratio, mold stains during vulcanization occur. As the chlorinated ethylene / propylene copolymer rubber, a commercially available product (Mitrene, Mitsui Petrochemical Co., Ltd., etc.) can be used as it is.

[0012] The blended rubber to which the halogenated ethylene / propylene copolymer rubber is added is generally a blended rubber.
It is cross-linked by about 1 to 10 parts by weight, preferably about 2 to 8 parts by weight, of organic peroxide used per 100 parts by weight. As the organic peroxide, for example, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 2 , 5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,1,3-di (tert-butyl Peroxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tertiary butyl peroxybenzoate, tertiary butyl peroxyisopropyl carbonate, n
-Butyl-4,4-di (tert-butylperoxy) valerate and the like are used.

In the blend rubber composition, in addition to the above essential components, triallyl is used as a compounding agent for each rubber.
(Iso) cyanurate, trimethylolpropane trimethacrylate, polyfunctional compounds such as triallyl trimellitate, carbon black, reinforcing agents such as fine silica,
Fillers such as talc, clay, graphite and calcium silicate; processing aids such as stearic acid, palmitic acid and paraffin wax; acid acceptors such as magnesium oxide, hydrotalcite and epoxy resin; antioxidants; plasticizers The compounding agents generally used in the rubber industry are appropriately added and used as necessary.

The blended rubber composition is prepared by kneading using a kneading machine such as an intermix, kneader, Banbury mixer or an open roll, and vulcanizing the same using an injection molding machine, a compression molding machine, or the like. Using a vulcanizing press or the like, generally performed by heating at about 150 to 200 ° C. for about 3 to 60 minutes, and if necessary, about 120 to 200
Secondary vulcanization is carried out by heating at a temperature of about 1 to 24 hours.

[0015]

By adding a small amount of halogenated ethylene / propylene copolymer rubber to a blend rubber of hydrogenated NBR and ethylene / propylene copolymer rubber,
The compatibility between both blended rubbers can be significantly improved. As a result, not only the balance between cold resistance and oil resistance is excellent, but also peel resistance and Freon resistance (R12, R1
34a) Since the property is also good, it can be suitably used as a molding material of a sealing material used in a place where it comes into contact with water, oil, chlorofluorocarbon, LLC or the like.

[0016]

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

Comparative Example 1 Hydrogenated NBR 60 parts by weight [Zetpol 3110 manufactured by Nippon Zeon; nitrile content 25%, iodine value 15] Ethylene-propylene copolymer rubber 40〃 [Mitsui Petrochemical EPT 14030; Mooney viscosity (100 ° C.) ) 27, Fluorene content 42%] SRF carbon black 30 0.5 0.5 stearic acid 0.5 〃 zinc 2-mercaptobenzimidazole 0.5 〃 1,3-bis (tert-butylperoxyisopropyl) benzene 2.5 〃 The kneaded material was vulcanized at 170 ° C. for 20 minutes.

The following items were measured and evaluated with respect to the obtained vulcanized product. Normal physical property: JIS K-6301 compliant Oil resistance: Volume change rate after immersion in JIS No. 1 oil at 150 ° C for 70 hours LLC resistance: Under 50% non-amine LLC liquid at 120 ° C for 500 hours Volume change rate after immersion Cold resistance (TR-10): ○ for -35 ° C or less, △ for -31 to -34 ° C, -30
℃ or more can be evaluated as × Peeling resistance: between two rubber cloths 1mm thick and 100mm long
After vulcanizing the cellophane sheet by a length of 50 mm and removing the cellophane sheet, a 180 ° peel test was performed. Material destruction was evaluated as ○, and complete delamination as ×. When vulcanizing with a suitable mold, count the number of shots until chipping occurs in the vulcanized molded product,
11 or more shots were evaluated as ○, 10-3 as Δ, 2-1 as ×

Example 1 In Comparative Example 1, 10 parts by weight of a chlorinated ethylene / propylene copolymer rubber (Miprene CE, Mitsui Petrochemical Co.) was used.

Example 2 In Example 1, another ethylene-propylene copolymer rubber (Mitsui Petrochemical EPT3045; Mooney viscosity (100 ° C.) 4
5, propylene content 43%).

Comparative Example 2 In Comparative Example 1, 100 parts by weight of hydrogenated NBR was used, and no ethylene / propylene copolymer rubber was used. The amount of the organic peroxide was changed to 2.0 parts by weight.

Comparative Example 3 In Comparative Example 1, 100 parts by weight of an ethylene / propylene copolymer rubber was used, and hydrogenated NBR was not used. The amount of the organic peroxide was changed to 2.0 parts by weight.

Comparative Example 4 In Comparative Example 1, 100 parts by weight of hydrogenated NBR was used, and 15 parts by weight of a chlorinated ethylene / propylene copolymer rubber (Miprene CE) was used instead of the ethylene / propylene copolymer rubber. Used.

Comparative Example 5 In Comparative Example 1, 100 parts by weight of hydrogenated NBR was used, and 35 parts by weight of chlorinated ethylene / propylene copolymer rubber (Miprene CE) was used instead of the ethylene / propylene copolymer rubber. Used. Further, the amount of the organic peroxide was changed to 3.5 parts by weight.

The measurement and evaluation results in the above Examples and Comparative Examples are shown in Table 1 below. Table 1 item ratio-1 real-1 real-2 ratio-2 ratio-3 ratio-4 ratio -5 [Physical properties] Hardness (JIS A) 62 61 62 60 59 60 60 Tensile strength (MPa) 16.7 17.2 18.6 19.6 13.7 18.9 17.0 Elongation (%) 360 390 360 400 220 360 320 [Oil resistance] ΔV (%) +29 +30 +31 +4 +89 +20 +30 [LLC resistance] ΔV (%) +2 + 2 +2 +3 +1 +2 +2 [TR-10] (℃) -33 -36 -33 -30 -48 -30 -33 [Removal resistance] × ○ ○ ○ ○ ○ ○ [Stain resistance] ○ ○ ○ ○ ○ ○ ×

Further, when the cross section of the vulcanized sheet was observed using a reflected electron image of an electron microscope, in the case of Comparative Example 1, the ethylene-propylene copolymer rubber became striped in the hydrogenated NBR. In contrast to the separation into several pieces, Example 2
In the case of the above, it was confirmed that both were uniformly compatible with each other.

Comparative Example 6 Hydrogenated NBR 70 parts by weight [Zetpol 2020 manufactured by Zeon Corporation; nitrile content 36%, iodine value 28] Ethylene / propylene copolymer rubber 30 ゴ ム [Mitsui Petrochemical EPT 3070; Mooney viscosity (100 ° C.) ) 65, Fluorene content 50%] SRF carbon black 60 亜 鉛 zinc oxide 5 〃 stearic acid 1 〃 dicumyl peroxide 4 〃 The above components are kneaded with a kneader, and the kneaded material is kneaded at 170 ° C. for 20 minutes. Vulcanized.

The obtained vulcanized product was measured for physical properties in a normal state and evaluated for CFC resistance. Freon resistance: 4 in R12 (CCl ₂ F ₂ ) or R134a (CH ₂ FCF ₃ )
After immersion at 0 ° C for 24 hours, heat at 150 ° C for 1 hour and visually check for blisters on the surface of the test piece

Example 3 In Comparative Example 6, 10 parts by weight of a chlorinated ethylene / propylene copolymer rubber (Miprene CE) was further used.

Comparative Example 7 In Comparative Example 6, 100 parts by weight of hydrogenated NBR was used, and no ethylene / propylene copolymer rubber was used.

Comparative Example 8 In Comparative Example 6, 100 parts by weight of an ethylene / propylene copolymer rubber was used, and no hydrogenated NBR was used.

The measurement and evaluation results in Example 3 and Comparative Examples 6 to 8 are shown in Table 2 below. Table 2 Item ratio-6 Actual-3 ratio-7 Ratio-8 [Normal physical properties] Hardness (JIS A) 74 73 75 73 Tensile strength (MPa) 26.9 26.2 31.0 15.9 Elongation (%) 310 330 280 370 [Resistance R12a Yes No No Yes R134a Yes No Yes No

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C08L 23:28) C08L 23:28) (56) References JP-A-61-283639 (JP, A) JP-A-6-128415 (JP, A) JP-A-64-20251 (JP, A) JP-A-1-292048 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 9/02 C08L 23 / 16 C09K 3/10

Claims (2)

(57) [Claims] 1. A blend rubber composition comprising about 3 to 30 parts by weight of a halogenated ethylene / propylene copolymer rubber per 100 parts by weight of a blended rubber of hydrogenated NBR and ethylene / propylene copolymer rubber. 2. The blended rubber composition according to claim 1, which is used as a sealing material molding material.