JP4449130B2 - Rubber seal material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber seal material. More specifically, the present invention relates to a rubber seal material in which a non-adhesive and low frictional resistance surface layer is formed.
[0002]
[Prior art]
The following problems are observed in rubber vulcanized products.
-Adheres to each other when stacked or packaged, etc., and there is a problem in work-- Adhesive to elastic bodies and mating contact surfaces when rubber parts are assembled, especially between automatic parts when automatically mounting with parts feeder etc. Automatic mounting is difficult due to adhesion of the rubber. ・ Slipping of rubber parts surface is not good, so sliding resistance and operating resistance after installation are large, operation stops, and problems with large vibration and slip noise occur.・ If a rubber part is used for a long time after it has been assembled, it will stick to or adhere to a mating material such as metal, resin, glass, etc., making it difficult for the device to malfunction or to be removed during replacement. Grease, lubricating oil, etc. may be applied to the surface, but since these are liquid, they are easily removed by contact, and there is no persistence in reducing non-adhesiveness and operating resistance.
Japanese Patent Application Laid-Open No. 55-28849 describes a method for preventing adhesion of rubber to form a molten film of an adhesion preventive agent that is non-adhesive and heat-meltable to rubber. It is stated that waxes, natural waxes, low molecular weight olefin polymers, esters, stearic acid (metal salt), ethylene bisstearylamide, etc. are used, and preferably waxy organic substances are used.
[0004]
However, when polyethylene wax is applied to a vulcanized rubber molded product and heat-treated, the adhesion between the rubber and the polyethylene film is not good and is easily peeled off when rubbed. Further, when the heat treatment temperature is equal to or higher than the softening point of polyethylene wax, the polyethylene wax becomes liquid, and the polyethylene wax may aggregate on the smooth surface of the compression-vulcanized rubber molded product, so that a uniform film may not be formed. On the other hand, when the heat treatment temperature is lower than the softening point of polyethylene wax, although the polyethylene wax does not aggregate, the fine particle shape of the wax remains and the particles tend to fall off. When the wax peeled off due to such a cause comes into contact with the seal portion, the sealability is deteriorated or a defect to other portions is caused.
[0005]
JP-A-63-8428 describes a rubber elastic surface treatment solution comprising an aqueous dispersion or emulsion of a low molecular weight polyethylene wax, but in that polyethylene wax is used, The same drawbacks are seen.
[0006]
Further, JP-A-63-8436 discloses a surface treatment solution for a rubber elastic body in which a fatty acid metal salt, amide wax, solid paraffin and dimethylsiloxane silicone oil are dissolved, dispersed or emulsified in a solvent. Yes. When this surface treatment liquid is applied to a rubber elastic body and cured by heating, the amide wax and solid paraffin dissolve in the silicone oil, but the fatty acid metal salt does not dissolve, so it remains on the rubber surface while maintaining its particle shape. The sealing performance is deteriorated. In addition, when applied to the smooth surface of a compression-vulcanized rubber molded product, the wax may aggregate due to heat treatment, and a uniform film may not be formed.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a rubber seal material in which a wax coating having non-adhesiveness and low frictional resistance is formed, which is excellent in coating formation and sealing properties.
[0008]
[Means for Solving the Problems]
The object of the present invention is achieved by a rubber seal material in which a film containing only an amide wax as a wax component is formed on the surface of a vulcanized rubber molded article having a surface roughness of 1 to 30 μm.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
As the vulcanized rubber molded product, a vulcanized molded product of synthetic rubber or natural rubber such as fluorine rubber, acrylic rubber, NBR, SBR, EPDM, silicone rubber or the like is used. As a method for forming a surface roughness on the surface of these vulcanized rubber molded article, roughening method by sandblasting the rubber molded article surface, roughening method rubbed with sandpaper or the like, a mold subjected to roughening process using For example, a method of transferring irregularities on the surface of a rubber molded product by performing compression molding, injection molding, or the like is used .
[0010]
The surface roughness formed on the rubber molded product surface is indicated by an average value obtained from a cross-sectional curve according to JIS B-0601, and the value must be in the range of 1 to 30 μm, preferably 2 to 20 μm. . When the surface roughness is smaller than this, a wax film formed by applying wax and heat-treating is not uniformly formed, and adhesion with a metal or the like at a high temperature is observed. On the other hand, if the surface roughness is larger than this, the sealing performance is impaired.
[0011]
Examples of the amide-based wax for forming a film include fatty acid amides such as stearic acid amide and lauric acid amide, ethylene bis stearic acid amide, stearyl stearic acid amide, methylol stearic acid amide, ethylene bislauric acid amide, and hexamethylene bisoleic acid amide. N-substituted fatty acid amides such as xylylene bis-stearic acid amide or N-substituted aromatic amides are used.
[0012]
These amide waxes have a softening point of 60 ° C. or higher, preferably 100 to 170 ° C., and a molecular weight of 100 to 1000, preferably 400 to 600. Naturally, the higher the molecular weight, the higher the softening point. . When the softening point and molecular weight are lower than this, stickiness occurs at room temperature, and non-adhesiveness and low friction properties are lowered. On the other hand, when the molecule is larger than this, the adhesion to rubber is lowered.
[0013]
As a method for forming a film by applying these amide waxes, preferably amide waxes having a particle size of about 0.1 mm or less to the surface of the vulcanized rubber molded article, the wax may be an organic solvent such as isopropanol or toluene, or water. After the dispersion is dispersed on the rubber surface by the dipping method, spray method, roll coater method, flow coater method, etc., it is generally affected by the softening point of the wax used, but is generally about 120 to 200 ° C. Heat treatment for about 2 to 30 minutes, or a method in which the wax is pulverized to 0.5 mm or less, preferably about 0.1 mm or less and dusted on the rubber surface and then heated and melted above the softening point of the wax (dusting-melting) Method), a method in which the wax is heated to a temperature higher than the softening point, and a melt-liquefied wax is applied.
[0014]
In the former method, the dispersion is applied to the surface of a vulcanized rubber molded product in a high-temperature state immediately after vulcanization, and the wax is melted at the same time as the application, instead of the heat treatment method after application at room temperature. It can also be processed. Also, depending on the rubber material, if left at room temperature after molding, other wax, plasticizer, processing aid, etc. in the rubber bloom on the surface of the rubber molded product, and when the dispersion is applied in this state, Since uniform application may become difficult and adhesion to rubber may be reduced, it may be preferable to apply the wax in the melted liquid state by heating the wax by the latter method.
[0015]
The amide wax coating formed on the surface of the vulcanized rubber molded product does not necessarily fill the surface roughness portion of 1 to 30 μm, and is generally formed with a film thickness of about 0.1 to 10 μm, preferably about 0.5 to 5 μm. .
[0016]
【The invention's effect】
The amide wax film-forming rubber seal material according to the present invention has the following effects.
(1) Since a vulcanized rubber molded product having a surface roughness is used, the coating property of the amide wax surface treating agent is excellent.
(2) No blocking between the surface-treated rubber molded products is observed.
(3) The surface of the surface-treated rubber molded product has low friction and low sliding, and is excellent in mounting workability.
(4) There is little adhesiveness and adhesiveness between metals and the like, and such a tendency is maintained even at high temperatures. This is because a chemical bond is formed between the functional group of the rubber and the amide wax surface treatment agent, and the anchoring effect due to the roughness of the rubber surface is also exhibited. As a result, the durability of the surface-treated sealing material It is considered that non-adhesiveness at high temperatures is exhibited.
(5) Even if the coating thickness of the amide wax coating is thin, the desired performance is sufficiently exhibited, the cost can be reduced, and coating unevenness is not observed.
(6) Since the coating thickness is thin, the rubber physical properties and sealing properties of the rubber sealing material are not impaired.
[0017]
The rubber seal material of the present invention showing such effects is a rubber seal material used for preventing leakage of liquid or gas, for example, O-ring, square ring, D-ring, oil seal, V-packing, packing, gasket, diaphragm, various valves Etc. can be used effectively.
[0018]
【Example】
Next, the present invention will be described with reference to examples.
[0019]
Example 1
NBR made of 5% by weight isopropanol dispersion of ethylene bis-stearic acid amide (Lion product armo wax EBS-P) (wax particle size of 0.01 mm or less in the wax dispersion) with mold irregularities transferred during compression vulcanization molding An NBR vulcanized sheet with a wax film formed by applying it to the surface of a vulcanized sheet (surface roughness 10 μm) with a coating thickness of about 2 to 5 μm, followed by heat treatment at 160 ° C. for 10 minutes. (Surface treatment sheet) was obtained.
[0020]
The surface treatment sheet was measured for the following items.
(Wax film formation test)
The condition of the coating on the surface-treated sheet (100 x 100 x 2 mm) after cooling at room temperature is visually observed. ○: There is no unevenness and it is applied evenly. ×: There is repellency and unevenness and it is applied to the entire surface. Not rated in two stages
(Adhesion test with vulcanized rubber )
In accordance with JIS K-5400, cellophane tape is applied to the surface of a surface treatment sheet (100 x 100 x 2 mm), and the state of peeling of the wax film after peeling the tape is evaluated as large or small.
(Dynamic friction coefficient measurement test)
In accordance with ASTM D-1894, the surface friction coefficient of the surface treated sheet is determined by using Shinto Kagaku's surface properties when the mating material is a 10 mm diameter chrome steel ball friction element, the moving speed is 50 mm / min, and the load is 50 g. Measured with a testing machine
(Adhesion test between vulcanized rubbers )
Surface treatment sheets (60 × 25 × 2mm) are placed in a constant temperature and humidity chamber at 40 ° C and 95% R, and after pressure bonding for 24 hours at a surface pressure of 0.15Kg / cm ² , tensile shear bonding of JIS K-6850 follow the test method measures the tensile strength of the shear bond strength test specimen tensile at room temperature conditions, evaluating the surface tack
(High temperature adhesion test with metal)
Surface treatment sheet (60 × 25 × 2mm) and aluminum plate are placed in a thermostatic chamber at 130 ° C, and then treated and evaluated in the same manner as the NBR-to-NBR adhesion test.
(Seal leak test)
As with the surface treatment sheet, an uneven NBR O-ring with a wax coating (nominal number P8; inner diameter 7.8 mm, linear 1.9 mm) was compressed 15% with a stainless steel plate to check for leaks in the helium leak test. Judgment [0021]
Example 2
In Example 1, a wax dispersion was applied at a high temperature immediately after compression vulcanization, and the wax was melted and applied.
[0022]
Example 3
In Example 1, fluororubber was used instead of NBR, and the heating conditions were changed to 180 ° C. for 10 minutes.
[0023]
Example 4
In Example 1, EPDM was used instead of NBR, and the heating conditions were changed to 180 ° C. for 10 minutes.
[0024]
Example 5
In Example 1, instead of the wax dispersion, a finely pulverized product of ethylenebisstearic acid amide (wax particle size of 0.1 mm or less) was used, and its application was performed by a dusting-melting method.
[0025]
Comparative Example 1
In Example 1, an NBR vulcanizate having a surface roughness of 0.5 μm to which the unevenness of the mold was transferred was used.
[0026]
Comparative Example 2
In Example 1, an NBR vulcanizate having a surface roughness of 50 μm to which the unevenness of the mold was transferred was used.
[0027]
Comparative Example 3
In Example 1, a wax dispersion formed from 10 parts by weight of a low molecular weight polyethylene dispersion (Mitsui Chemicals Chemipearl W-400; solid concentration 40% by weight) and 70 parts by weight of water was used.
[0028]
Comparative Example 4
In Example 1, as a wax dispersion, zinc stearate 8 parts by weight, ethylenebisstearic acid amide (Armo wax EBS-P) 4 parts by weight, 135F paraffin (Mobil petroleum products) 10 parts by weight, silicone oil (Shin-Etsu Chemical products) KF96-100CS) and 5 parts by weight of toluene and 513 parts by weight of toluene were used.
[0029]
Comparative Example 5
In Example 1, a 5 wt% toluene dispersion of methyl silicone oil (Shin-Etsu Chemical KF96) was used as the wax dispersion.
[0030]
The measurement or evaluation results in Examples 1 to 5 and Comparative Examples 1 to 5 are shown in the following table.
table
Wax vulcanized rubber vulcanized rubber with metal
Adhesion of dynamic friction with coating High temperature adhesion Sealing material
Examples forming the adhesion coefficient ^{(g / cm 2) (g} / cm 2) leakage <br/> Example 1 〇 peeling small 0.3 0 0 〇 〃 2 〇 〃 0.3 undefined undefined undefined
〃 3 〇 〃 0.2 〃 〃 〃
〃 4 〇 〃 0.3 〃 〃 〃
〃 5 〇 〃 0.2 〃 〃 〃
Comparative Example 1 × 〃 0.4 〃 200 〃
〃 2 〇 〃 0.4 〃 0 ×
〃 3 × Peel large 0.4 〃 1300 ×
〃 4 × Small peeling 0.08 〃 800 ×
〃 5 × 〃 0.05 200 600 〇

Claims (4)

A rubber seal material obtained by forming a film containing only an amide wax on the surface of a vulcanized rubber molded article having a surface roughness of 1 to 30 μm. The rubber seal material according to claim 1, wherein the amide wax is a fatty acid amide, an N-substituted aliphatic amide or an N-substituted aromatic amide having a softening point of 60 ° C or higher and a molecular weight of 100 to 1000. The rubber seal material according to claim 1, wherein the amide wax film is formed by applying a wax dispersion to the surface of the vulcanized rubber molded article and heat treatment. The rubber seal material according to claim 1, wherein the amide wax film is formed by a wax dusting-melting method.