JP2000212333A - Hydrogenated nbr composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hydrogenated NBR composition whose heat-resistance and low-temperature properties were improved substantially without spoiling its original mechanical strength (normal state physical properties) or oil- resistance. SOLUTION: This composition is obtained by including 100 pts.wt. of hydrogenated NBR which contains bound acrylonitrile at 15-30 wt.%, 30-100 pts.wt. of white carbon having a specific surface area of 200 m2/g or less, and 1-10 pt(s).wt. of a organic peroxide, and preferably 1-10 pt(s).wt. of a multifunctional unsaturated compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydrogenated NBR composition. More specifically, the present invention relates to a hydrogenated NBR composition capable of providing a vulcanizate having excellent heat resistance and low-temperature properties.

[0002]

2. Description of the Related Art The applicant of the present invention has previously proposed a hydrogenated NBR 100 to improve its heat resistance without substantially impairing the mechanical strength (normal physical properties) and oil resistance inherent to hydrogenated NBR. About 3 parts by weight, white carbon with a specific surface area of about 20 to 200 m ² / g
A hydrogenated NBR composition containing 0 to 150 parts by weight and about 1 to 10 parts by weight of an organic peroxide has been proposed (JP-A-9-3246).

[0003] Regarding the hydrogenated NBR, which is a main component of the composition proposed here, mention is made of the amount of carbon-carbon double bonds in the molecular main chain and Mooney viscosity ML _{1 + 4} (100 ° C). However, there is no mention of the amount of bound acrylonitrile (AN amount), and the AN amount of Zetpol 2000 manufactured by Zeon Corporation of Japan used in the example is 36% by weight.

However, hydrogenated NB having such a high AN content
Although the above composition using R is excellent in heat resistance, it has a problem that low-temperature characteristics cannot be satisfied.

[0005]

An object of the present invention is to improve the heat resistance and low-temperature properties of hydrogenated NBR without substantially impairing the mechanical strength (normal physical properties) and oil resistance inherent to hydrogenated NBR. To provide a hydrogenated NBR composition.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
Hydrogenated NBR100 with bound acrylonitrile content of 15-30% by weight
30 parts by weight of white carbon with a specific surface area of 200 m ² / g or less
This is achieved by a hydrogenated NBR composition containing -100 parts by weight and 1-10 parts by weight of an organic peroxide, preferably further containing 1-10 parts by weight of a polyfunctional unsaturated compound.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hydrogenated NBR has an AN amount of 15 to 3
0% by weight, preferably 20 to 25% by weight is used. A
If the N content is less than this, the oil resistance is poor, while if it is more than this, the effect of improving the low-temperature characteristics cannot be obtained. NBR which is a copolymer rubber of acrylonitrile and butadiene or a terpolymer rubber further copolymerized with an ethylenically unsaturated compound.
Is used in the present invention to reduce the amount of carbon-carbon double bonds in the main chain of the molecule and to reduce the iodine value of the double bond to 30 or less, preferably 20 or less. The Mooney viscosity ML _{1 + 4} (100 ° C.) is generally about 60 to 100, but may be 100 or more. Actually, for example, those having an AN amount specified by, for example, those of Nippon Zeon's Z-pole series are used.

[0008] White carbon (reinforcing silica) is a dry-type white carbon produced by a thermal decomposition method of a halogenated silicic acid or an organic silicon compound or a method of heating and reducing silica sand and oxidizing vaporized SiO with air. carbon, and the like wet process white carbon produced by thermal decomposition of sodium silicate, the ratio (by nitrogen adsorption method) surface area of about 200 meters ² / g or less, and preferably about 30~130m ² / g And commercially available products generally marketed for the rubber industry can be used as they are. If the specific surface area is smaller than this, the reinforcing property as white carbon cannot be obtained, while, if the specific surface area is larger than this, the particle diameter of white carbon is too small and the reinforcing property becomes too strong, The increase in viscosity of the composition makes kneading difficult, and the vulcanizate becomes very hard.

These white carbons are hydrogenated NBR1
It is used in an amount of about 30 to 100 parts by weight, preferably about 50 to 80 parts by weight, per 100 parts by weight. If the mixing ratio is less than this, the effect of improving heat resistance, which is one of the objectives, is not achieved,
On the other hand, if it is used in a higher ratio, kneading becomes difficult not only due to an increase in the viscosity of the composition, but also the rubber hardness becomes extremely high and the rubber elasticity is lost.

[0010] Vulcanization of hydrogenated NBR containing white carbon must be carried out using an organic peroxide.

Examples of the organic peroxide include di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di (tert-butyl peroxy) -3,3,5-trimethyl Cyclohexane, 2,5-dimethyl-
2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-
2,5-di (tert-butylperoxy) hexyne-3,1,3-di (tertiary
(Butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tertiary butylperoxybenzoate, tertiary butylperoxyisopropyl carbonate, n-butyl-4,4'-di (Tertiary butyl peroxy) valerate etc. is about 1 per 100 parts by weight of hydrogenated NBR
To 10 parts by weight, preferably about 2 to 8 parts by weight. If the compounding amount of the organic peroxide is less than this, a vulcanizate having a sufficient cross-linking density cannot be obtained. Even if it does, rubber elasticity and elongation will decrease.

In the composition, besides the above essential components, a polyfunctional unsaturated compound such as triallyl (iso) cyanurate, trimethylolpropane tri (meth) acrylate, triallyl trimellitate, etc. is used. About 1 per
It is preferable that the compounding amount is from 10 to 10 parts by weight, preferably about 2 to 8 parts by weight. The incorporation of the polyfunctional unsaturated compound is effective for further improving the heat resistance, particularly the compression set at that time.
However, when used at a higher ratio, the rubber elasticity and elongation are reduced.

The composition contains carbon black, for example, furnace black produced by incomplete combustion of oil, and thermal black produced by thermally decomposing natural gas. About 20 parts by weight or less per 100 parts by weight of NBR. As shown in the results of Comparative Example 2 below, when carbon black was used in place of the required amount of white carbon, the low-temperature characteristics were good, but the heat resistance was inevitably reduced. The combined use with white carbon improves low-temperature characteristics without substantially lowering heat resistance.

In addition, talc, clay, graphite,
Commonly used in the rubber industry such as fillers such as calcium silicate, processing aids such as stearic acid, palmitic acid and paraffin wax, acid acceptors such as zinc oxide and magnesium oxide, antioxidants and plasticizers Various compounding agents are appropriately added and used.

The composition is prepared by kneading using a kneading machine such as an intermix, kneader, Banbury mixer or an open roll, and vulcanization is performed by using an injection molding machine, a compression molding machine, a vulcanizing press. And the like, generally by heating at about 150 to 200 ° C. for about 3 to 60 minutes, and further at about 120 to 200 ° C. for about 1 to 24 if necessary.
Secondary vulcanization with time heating is also performed.

[0016]

According to the present invention, by blending white carbon with hydrogenated NBR having a specific amount of bound acrylonitrile and vulcanizing it with an organic peroxide, the mechanical strength (vulcanized physical properties) inherent in hydrogenated NBR and Its heat resistance and low temperature properties can be simultaneously improved without substantially impairing the oil resistance.

Therefore, the hydrogenated NBR composition according to the present invention is effective as a molding material for sealing parts used under temperature conditions of -40 ° to + 150 ° C., for example, O-rings, gaskets, packings, oil seals and the like. Used for

[0018]

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

Example 1 Hydrogenated NBR (AN 25%, iodine value 15, ML _{1 + 4} 95) 100 parts by weight Reinforcing silica (specific surface area 100 m ² / g) 60 〃 FEF carbon black 10 亜 鉛 Zinc oxide 5 ポ リ Polymerized ( 2,2,4-trimethyl-1,2-dihydroquinoline) 0.5 〃 2-mercaptobenzimidazole 2 ジ オ dioctyl sebacate 10 〃 dicumyl peroxide 5 〃 Press vulcanization at 170 ° C for 20 minutes
Oven vulcanization (secondary vulcanization) was performed at 60 ° C. for 3 hours to obtain a vulcanized sheet (150 × 150 × 2 mm).

Example 2 In Example 1, 5 parts by weight of triallyl isocyanurate was additionally used.

Comparative Example 1 In Example 1, the hydrogenated NBR was AN36% and the iodine value was 11
Was used.

Comparative Example 2 In Example 1, the amount of reinforcing silica was changed to 10 parts by weight,
The amount of EF carbon black was changed to 60 parts by weight.

Comparative Example 3 In Example 1, if the amount of reinforcing silica was changed to 120 parts by weight, kneading was impossible.

Comparative Example 4 In Example 1, the reinforcing silica had a specific surface area of 300 m ^2.
When k / g was used, kneading was impossible.

Comparative Example 5 In Example 1, the amount of dicumyl peroxide was changed to 0.5 parts by weight.

Comparative Example 6 When the amount of dicumyl peroxide was changed to 12 parts by weight in Example 1, kneading was possible, but vulcanization molding was not possible.

The following items were measured for the vulcanized sheets obtained in Examples 1-2 and Comparative Examples 1-2 and Comparative Example 5, and the results shown in the following table were obtained. . Normal physical properties: JIS K-6253, JIS K-6251 compliant Heat resistance: JIS K-6257 compliant (hardness change after standing at 150 ° C for 70 hours or 500 hours) JIS K-6262 compliant (150 ° C at 70 hours or 500 Low-temperature properties: according to ASTM D-1329 (TR-10 value) Table Example Comparative Example Measurement Item 1 2 1 2 5 [Normal Physical Properties] Hardness (Durometer A) 75 78 80 75 70 Tensile Strength (MPa) 24.5 25.1 27.5 24.9 22.5 Elongation (%) 260 210 270 260 480 [Heat resistance] 150 ° C, 70 hours Hardness change (point) +3 +3 +3 +6 +5 Compression set (%) 18 15 17 20 73 150 ° C, 500 hours Hardness change (point) +9 +7 +8 +17 +13 Compression set (%) 32 28 33 55 100 [Low temperature characteristics] TR-10 (° C) -37- 36 -24 -36 -37

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/14 C08K 5/14 5/3477 5/3477 C08L 9/02 C08L 9/02

Claims (3)

[Claims] 1. The amount of bound acrylonitrile is 15 to 30% by weight.
A hydrogenated NBR composition comprising 100 parts by weight of hydrogenated NBR, 30 to 100 parts by weight of white carbon having a specific surface area of 200 m ² / g or less, and 1 to 10 parts by weight of an organic peroxide. 2. The hydrogenated NBR composition according to claim 1, further comprising 1 to 10 parts by weight of a polyfunctional unsaturated compound. 3. The hydrogenated NBR composition according to claim 1, further comprising carbon black.