JPH093246A - Hydrogenated nbr composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition composed of a hydrogenated NBR, a white carbon and an organic peroxide, having an improved heat resistance without deteriorating mechanical strength (vulcanization property) and oil resistance and useful as a various kinds of sealing materials used for an engine, a compressor, etc., of an automobile. CONSTITUTION: This hydrogenated NBR composition is composed of (A) a hydrogenated NBR, (B) a white carbon and (C) an organic peroxide. The component A is obtained by hydrogenating a copolymer rubber (NBR) of acrylonitrile and butadiene to reduce the amount of C-C double bonds in the molecular main chain to about <=20%, preferably about <=10%. The component B is a dry- method white carbon or a wet-method white carbon and has a specific surface area of about 20-200m<2> /g, preferably about 30-100m<2> /g. The component C is di-tert-butylperoxide, di-cumylperoxide, etc. Further, 100 pts.wt. of the component A is preferably compounded with about 50100 pts.wt. of the component B and about 2-8 pts.wt. of the component C.

Description

Detailed Description of the Invention

[0001]

This invention relates to hydrogenated NBR compositions. More specifically, hydrogenated NB with improved heat resistance
R composition.

[0002]

2. Description of the Related Art Hydrogenated NBR is effectively used as a sealing material molding material for oil seals, packings, O-rings and the like because it has excellent mechanical strength and oil resistance. However, due to the high temperature in recent years due to higher performance, smaller size, lighter weight, etc., a new problem has been raised that conventional hydrogenated NBR has insufficient heat resistance.

[0003]

The object of the present invention is to improve the heat resistance of hydrogenated NBR without substantially impairing the excellent mechanical strength (vulcanized physical properties) and oil resistance inherent to hydrogenated NBR. It is to provide a hydrogenated NBR composition.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
Achieved by a hydrogenated NBR composition containing hydrogenated NBR, white carbon and an organic peroxide.

As the hydrogenated NBR, a copolymer rubber (NBR) of acrylonitrile and butadiene is hydrogenated, and the amount of carbon-carbon double bonds in the molecular main chain is adjusted to about 20% or less, preferably about 10% or less. What is done is used. The Mooney viscosity ML _{1 + 4} (100 ° C.) is generally about 60 to 85, but 100 or more can be used. In practice, for example, those of Nippon Zeon Product Zet Pole series are used.

As white carbon (reinforcing silica), a dry method white produced by a thermal decomposition method of a halogenated silicic acid or an organic silicon compound, a method of heating and reducing silica sand, and an air oxidation of vaporized SiO. carbon, sodium silicate and the like with pyrogenic wet process white carbon produced by such a specific surface area (by nitrogen adsorption method) of about 20 to 200 m ² / g, preferably about 30 to 100 m ² / g The 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 size of white carbon becomes too small,
Problems such as poor dispersion in rubber will occur.

These white carbons are hydrogenated NBs.
About 30 to 150 parts by weight, preferably about 50 to 10 parts by weight per 100 parts by weight of R
Used in a proportion of 0 parts by weight. If the blending ratio is less than the above range, the desired heat resistance improving effect is not achieved, while if the blending ratio is more than the above range, the rubber hardness becomes extremely high and the rubber elasticity is also lost.

Hydrogenated NBR blended with white carbon
The vulcanization of must be done with organic peroxides,
In the sulfur vulcanization system, no particular difference was observed between white carbon and carbon black, and the effect of improving heat resistance was not achieved.

Examples of the organic peroxide include ditertiary butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, and 1,1-di (tertiary butylperoxy) -3,3,5-trimethyl. Cyclohexane, 2,5-dimethyl-
2,5-di (tertiary butylperoxy) hexane, 2,5-dimethyl-
2,5-di (tertiary butylperoxy) hexyne-3,1,3-di (tertiary butylperoxy)
Butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, n-butyl-4,4'-di (Tertiary butylperoxy) valerate is used in a proportion of about 1 to 10 parts by weight, preferably about 2 to 8 parts by weight, per 100 parts by weight of hydrogenated NBR.

In addition to the above essential components, the composition contains other polyfunctional compounds such as triallyl (iso) cyanurate, trimethylolpropane tri (meth) acrylate, triallyl trimellitate, and activated calcium carbonate. Reinforcing agents, fillers such as talc, clay, graphite and calcium silicate, processing aids such as stearic acid, palmitic acid and paraffin wax, acid acceptors such as zinc oxide and magnesium oxide, anti-aging agents and rubbers such as plasticizers. Various compounding agents generally used in industry are appropriately added and used.

The composition is prepared by kneading using an intermix, kneader, Banbury mixer or the like or an open roll, and the vulcanization is performed by an injection molding machine, a compression molding machine, a vulcanizing press. Etc., and is generally performed 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 is also performed by heating for a time.

[0012]

EFFECTS OF THE INVENTION By blending hydrogenated NBR with white carbon and vulcanizing it with an organic peroxide, the mechanical strength (vulcanization properties) and oil resistance originally possessed by hydrogenated NBR are almost impaired. Without it, the heat resistance of it can be improved. On the other hand, in the case of blending carbon black, rubber elasticity is lost when exposed to high temperature for a long time. In addition, the sulfur vulcanization system shows almost the same unsatisfactory heat resistance regardless of whether white carbon or carbon black is used.

Therefore, the hydrogenated NBR composition according to the present invention is effectively used as a molding material for various sealing materials used in automobile engines, compressors and the like.

[0014]

Next, the present invention will be described by way of examples.

Examples 1 to 3 Hydrogenated NBR (Nippon Zeon Product Zetpol 2000) 100 parts by weight Zinc oxide 5 〃 Stearic acid 1 〃 Diphenylamine anti-aging agent 1.5 〃 Imidazole anti-aging agent 1.5 〃 Dicumyl peroxide 4 〃 Trimellitic acid plasticizer 10 〃 vinylsilane compound 2 〃 wet white carbon (specific surface area 50 m ² / g) 80 〃 (Example 1) 〃 (〃 80 m ² / g) 60 〃 (Example 2) 〃 (〃 150 m ² / g) 50 〃 (Example 3) The above components were kneaded using a 3 L kneader and an open roll, and the kneaded product was press-vulcanized at 170 ° C. for 20 minutes.
(Primary vulcanization) and oven vulcanization (secondary vulcanization) at 160 ° C. for 3 hours were performed to vulcanize and mold into a sheet of 150 × 150 × 2 mm.

Regarding the obtained vulcanized sheet, JIS K-6301
In accordance with the standard, measurement of normal physical properties, aging test (1
70, 140 or 280 hours at 75 ° C) and immersion test (JIS No. 3
It was carried out in oil at 150 ° C. for 70 hours).

Comparative Examples 1 to 3 In Examples 1 to 3, carbon black was used instead of white carbon as follows, and the same measurement was performed on the obtained vulcanized sheets. Comparative Example 1 Carbon black N-990 120 parts by weight 〃 2 〃 N-770 90 〃 〃 3 〃 N-550 70 〃

The measurement results of the above examples and comparative examples are shown in Table 1 below. Table 1 Examples Comparative examples Measurement items 1 2 3 1 2 3 [Normal physical properties] Hardness (JIS A) 80 81 80 80 80 81 Tensile strength (MPa) 28.5 29.1 28.7 20.5 27.7 29.5 Elongation (%) 290 280 300 200 260 260 [Aging test; 70 hours] Hardness change (points) +4 +3 +4 +6 +7 +5 Tensile strength change rate (%) +22 +20 +22 +4 +3 +2 Elongation change rate (%) -22 -21 -25 -32 -31 -30 [Aging test; 140 hours] Hardness change (points) +6 +6 +6 +11 +11 +10 Tensile strength change rate (%) +21 +15 +17 -10 -7 -15 Elongation change rate (%) -34 -37 -33 -76 -69 -75 [Aging test; 280 hours] Hardness change (points) +8 +8 +9 +19 + 18 +18 Tensile strength change rate (%) +9 +10 +7 Unmeasurable due to hardening Elongation change rate (%) -54 -52 -57 〃 [immersion test] Hardness change (point) -6 -6- 7 -5 -6 -6 Tensile strength change rate (%) +3 +7 -5 -1 -2 +1 Elongation change rate (%) -5 -2 -4 -3 +4 -5 Volume change rate (%) ) +14.8 +15.0 +15.4 +13.9 +14.7 +15.1

From this result, the following can be said. (1) Each of the comparative examples completely loses rubber elasticity due to heat aging at 175 ° C. for 280 hours, but each of the examples has sufficient rubber-like elasticity. (2) The mechanical strength (particularly tensile strength) and the oil resistance (particularly the volume change rate in the immersion test) of each of the examples do not impair those of the conventional hydrogenated NBR.

Example 4 100 parts by weight of hydrogenated NBR (Zeonpol 1020 manufactured by Zeon Corporation) Zinc oxide 5 〃 Diphenylamine anti-aging agent 3 〃 Ether ester plasticizer 5 〃 Wet process white carbon (specific surface area 80 m ² / g) 40 〃 Dicumyl peroxide 4 〃 Vulcanization molding was performed in the same manner as in Examples 1 to 3 using the above components, and the vulcanized sheet thus obtained was subjected to measurement of normal state physical properties and aging test (compression set Measurements were also included).

Comparative Example 4 In Example 4, the same amount of white carbon was used instead of white carbon.
FEF carbon black was used, and the same measurement was performed on the obtained vulcanized sheet.

Comparative Example 5 In Example 4, a sulfur vulcanization system comprising the following components was used in place of dicumyl peroxide, and the same measurement was performed on the obtained vulcanized sheet. Thiuram-based vulcanization accelerator TT 2 parts by weight Thiazole-based vulcanization accelerator CZ 1 〃 Sulfur vulcanizing agent 0.5 〃

Comparative Example 6 In Example 4, the same amount of white carbon was used instead of white carbon.
FEF carbon black was used, the sulfur vulcanization system used in Comparative Example 5 was used instead of dicumyl peroxide, and the same measurement was performed on the obtained vulcanized sheet.

The measurement results of the above Example 4 and Comparative Examples 4 to 6 are shown in Table 2 below.

In addition to the above aging test, the compression set was measured under the following conditions. The results obtained are shown in Table 3. Table 3 Aging test conditions Temperature (℃) Time (hrs) Actual -4 ratio -4 ratio -5 ratio -6 100 168 20 17 86 72 〃 504 29 24 91 78 120 〃 37 32--150 〃 51 56--175 〃 69 87--

From the above results, the following can be said. (1) From the comparison of Comparative Examples 5 and 6, it can be said that there is almost no difference between the sulfur vulcanization system using white carbon and carbon black. (2) On the other hand, when comparing Example 4 using the peroxide vulcanization system and Comparative Example 4, when heating at 150 ° C. or higher for a long time, the case of using white carbon is better. It has been shown to have a lesser degree of thermal degradation than when using carbon black.

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[Procedure amendment]

[Submission date] January 10, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

The measurement results in each of the above Examples and Comparative Examples are shown in Table 1 below.

Claims (1)

[Claims] 1. A hydrogenated NBR composition comprising hydrogenated NBR, white carbon and an organic peroxide.