JPH11302451A - Nbr composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition with improved non-tackiness and moldability by adding a fatty acid amide and a metal salt of a fatty acid to an NBR blended with tetramethylthiuram monosulfide and zinc oxide as vulcanization system components. SOLUTION: A composition contains 100 pts.wt. of an NBR with an acrylonitrile content of 20-48 wt.%, 0.2-4 pts.wt. of a vulcanization accelerator such as tetramethylthiuram monosulfide, 1-10 pts.wt. of an accelerating auxiliary such as zinc oxide, 0.2-5 pts.wt. of a higher fatty acid amide selected from stearamide, oxystearamide, oleylamide and the like and 0.3-2 pts.wt. of a higher fatty acid such as sodium stearate and sodium oleate. If necessary, a reinforcing filler such as carbon black and silica, tetraethylthiuram disulfide to control coating thickness of the vulcanizing accelerator, an age resistor, a plasticizer and the like are further added to the composition. The composition is kneaded with a kneader and the like and then press vulcanized at 150-220 deg.C to form a vulcanized matter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an NBR composition. More specifically, NBR containing tetramethylthiuram monosulfide and zinc oxide as vulcanizing components
Composition.

[0002]

2. Description of the Related Art NBR, which has excellent oil resistance because of having a nitrile group which is a polar group, and is relatively inexpensive, is generally used for applications such as gas valves. The workability of NBR is relatively good, but it is used for gas valve seats and the like by adding an antioxidant and wax etc. in order to maintain heat resistance and weather resistance there. In some cases, it blooms on the product surface and causes sticking. In the case of complicated shapes such as gas valve seats,
Since it is pulled out of the mold in a vulnerable state during vulcanization molding, the product may be cracked.

[0003] In the case of NBR, tetramethylthiuram monosulfide is added as a vulcanization accelerator, and zinc oxide is added as a vulcanization accelerator.
Although BR compositions are known, it is not an exception that such NBR compositions have only the above-mentioned problems.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an NBR composition containing tetramethylthiuram monosulfide and zinc oxide as vulcanizing components, and to improve the non-adhesiveness and moldability of the composition. Is to provide things.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by an NBR composition obtained by adding a fatty acid amide and a fatty acid metal salt to NBR containing tetramethylthiuram monosulfide and zinc oxide as vulcanizing components, and the NBR composition is a vulcanized molding material such as a valve seat for gas. It is preferably used as

[0006]

DETAILED DESCRIPTION OF THE INVENTION As NBR, those having a nitrile content of about 20 to 48%, preferably about 28 to 43% are used.
NBRs having such a nitrile content include 10% of them.
About 0.2 to 4 parts by weight, preferably about 0.5 to 4 parts by weight of tetramethylthiuram monosulfide as a vulcanization accelerator per 0 parts by weight
33 parts by weight, and zinc oxide as a promoter, in an amount of about 1-10 parts by weight, preferably about 2-5 parts by weight.

[0007] NBR containing tetramethylthiuram monosulfide and zinc oxide as vulcanizing components include:
Further, fatty acid amides and fatty acid metal salts are added. The fatty acid amide blooms on the surface of the vulcanized molded product vulcanized by the vulcanization system to form a film, and reduces the adhesiveness. In addition, the fatty acid metal salt migrates to the surface of the vulcanized molded article during vulcanization as an internal release agent, and improves the releasability.

[0008] Fatty acid amides include stearoamide,
Higher fatty acid amides such as oxystearoamide, oleylamide and erucylamide are added in an amount of about 0.2 per 100 parts by weight of NBR.
To 5 parts by weight, preferably about 0.3 to 3 parts by weight. If the addition ratio is less than this, the desired detackifying effect cannot be obtained, while if it is used at a higher ratio, the amount of bloom increases and the coating becomes thicker, which is not preferable in appearance. As the fatty acid metal salt, higher fatty acids such as sodium stearate and sodium oleate are used in a ratio of about 0.3 to 2 parts by weight, preferably about 0.5 to 1.5 parts by weight, per 100 parts by weight of NBR. If the addition ratio is less than this, the desired releasability cannot be obtained, while if it is used at a higher ratio, the vulcanization properties are reduced. As these fatty acid amides and fatty acid metal salts, commercially available products can be used as they are.

[0009] Other components are added to the NBR composition containing the above components as essential components as necessary. Other compounding ingredients include carbon black and silica as reinforcing fillers, tetraethylthiuram disulfide for suppressing the film thickness of tetramethylthiuram monosulfide, an antioxidant, a plasticizer, and the like.

The composition is prepared by kneading the respective components using an internal mixer such as an intermix, Banbury mixer, kneader or an open roll, and vulcanization at about 150 to 220 ° C. , About 0.5 to 20 minutes, and if necessary further oven vulcanization.

[0011]

The NBR composition according to the present invention is excellent in non-adhesiveness and moldability. Particularly, a vulcanized molded product having a convex part in the middle is extracted from a mold having a concave part of a corresponding shape. In this case, there is an effect that cracking does not occur even if it is forcibly extracted. Utilizing such characteristics,
For example, it can be effectively used for vulcanization molding of a valve seat as described in Japanese Utility Model Laid-Open No. 1-113678.

[0012]

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

Comparative Example 1 NBR (Japanese synthetic rubber product N224SH, CN content 37%) 50 parts by weight NBR (Japanese synthetic rubber product N236H, CN content 32%) 50 〃 SRF carbon black 55 亜 鉛 zinc oxide 5 ス テ stearic acid 2 〃 2,2,4-trimethyl-1,2-dihydroquinone 2 〃 N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine 2 ワ ッ ク ス Wax (Seiko Chemical's SunTite R) 1 脂肪酸 Fatty acid amide ( Nippon Kasei's Daiamide O) 1.4 〃 Ester plasticizer (Asahi Denka RS107) 25 〃 Polymer polysulfide (Toyo Kagaku product bulker) 1.4 〃 Tetramethylthiuram monosulfide (Kawaguchi Chemical TS-10) 1.6 〃 Tetraethylthiuram Disulfide (Ouchi Emerging Chemicals TET-G) 0.6 〃 Dibenzothiazyl disulfide (DM-10) 0.6 〃 Each component above is kneaded with a kneader, and the kneaded material is pressed at 180 ° C for 4 minutes to obtain JIS K-
Normal physical properties were measured based on 6301.

Further, a vulcanized molded product having a convex portion in the middle was extracted from a mold having a concave portion of a corresponding shape, and the number of cracks of the molded product which was forcibly extracted was measured for 20 pieces.

[0015] Further, the adhesiveness of the surface of the vulcanized molded product after being left at room temperature for one month was judged by finger touch.

Example NBR (N224SH, CN content 37%) 70 parts by weight NBR (N236H, CN content 32%) 30 〃 SRF carbon black 80 亜 鉛 zinc oxide 5 〃 stearic acid 1 〃 2,2,4-trimethyl-1 , 2-Dihydroquinone 1 〃 N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine 1.5 〃 Wax (Santite R) 1 脂肪酸 Fatty acid amide (Diamid O) 0.5 〃 Fatty acid metal salt (S & S Japan products Structor WB16) 1.5 エ ス テ ル Ester plasticizer (RS107) 20 〃 Polymer polysulfide (Vulker) 1.4 テ ト ラ Tetramethylthiuram monosulfide (TS-10) 0.5 〃 Tetraethylthiuram disulfide (TET-G) 1.3 〃 Dibenzothiazyl The same kneading, vulcanization and measurement as in Comparative Example 1 were carried out using each component of disulfide (DM-10) 0.6% or more. The measurement items include the measurement of adhesive strength.
(After mounting the vulcanized molded product on the jig and applying a load of 400 g with a spring, leave it under the conditions of 40 ° C, 95% RH for 72 hours, release the load from the spring, and then stick with the load cell. Force).

Comparative Example 2 100 parts by weight of NBR (N224SH) SRF carbon black 85 亜 鉛 zinc oxide 5 1 stearic acid 1 〃 2,2,4-trimethyl-1,2-dihydroquinone 1.5 〃 N- (1,3-dimethyl Butyl) -N-phenyl-p-phenylenediamine 1.5 〃 Wax (Santite R) 2 脂肪酸 Fatty acid metal salt (Stractol WB16) 1.5 〃 Ester plasticizer (RS107) 25 〃 Sulfur 0.4 〃 Tetramethylthiuram disulfide 1.5 〃 N- Cyclohexyl-2-benzothiazylsulfenamide 2 用 い Using each of the above components, kneading, vulcanization and measurement were performed in the same manner as in Comparative Example 1.

Comparative Example 3 NBR (N224SH) 100 parts by weight SRF carbon black 40 亜 鉛 zinc oxide 5 〃 stearic acid 1 〃 2,2,4-trimethyl-1,2-dihydroquinone 1.5 〃 N- (1,3-dimethyl (Butyl) -N-phenyl-p-phenylenediamine 2 ワ ッ ク ス Wax (Santite R) 2 〃 Ester plasticizer (RS107) 15 〃 Sulfur 1 テ ト ラ Tetramethylthiuram disulfide 2 〃 N-cyclohexyl-2-benzothiazylsulfenamide Using the above components, kneading, vulcanization, and measurement were performed in the same manner as in Comparative Example 1.

The results obtained in the above Examples and Comparative Examples are shown in the following table. Table Measurement items Comparative example 1 Example Comparative example 2 Comparative example 3 [Physical properties] Hardness (JIS A) 58 60 60 60 Tensile strength (MPa) 15.2 14.0 14.9 14.7 Elongation (%) 450 500 610 420 (Moldability) ] Crack 20/20 0/20 0/20 20/20 [Tackiness] Presence or absence of tackiness None No Yes Yes Adhesive force (gf)-0.5 236 64

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16K 13/02 F16K 13/02

Claims (2)

[Claims] An NB obtained by further adding a fatty acid amide and a fatty acid metal salt to NBR containing tetramethylthiuram monosulfide and zinc oxide as vulcanizing components.
R composition. 2. A gas valve seat formed by vulcanization from the NBR composition according to claim 1.