JPH10159989A - Boots for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide maintenance free automobile boots excellent in grease oil content permeability resistance by vulcanizing and molding them from hydrogeneration on which Mooney viscosity is a specific range value. SOLUTION: A material on which Mooney viscosity ML1+4 (100 deg.C) is about 50 to 100 from a viewpoint of moldability, workability or the like and a double bond quantity is about 5 to 0% and the nitrile content is about 25 to 40wt.% is used as a hydrogeneration NBR. A hydrogeneration NBR composition to which a necessary compounding agent is added is prepared by kneading it for about 5 to 30 minutes by using a roller by adding a vulcanizing agent and a cross-linking assistant after being kneaded for about 3 to 10 minutes at a temperature of about 80 to 120 deg.C. It is vulcanized and molded as automobile boots under a condition where a metal mold temperature is about 150 to 250 deg.C and vulcanizing time is about 1 to 30 minutes by using a press molding machine or an injection molding machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile boot. More specifically, the present invention relates to an automobile boot that enables maintenance-free operation.

[0002]

2. Description of the Related Art A boot mounted on a drive shaft of an automobile, a constant velocity joint portion of the axle, or a propeller shaft that constantly rotates at a high speed has an important role of covering a grease required for smooth transmission of a driving force so as not to dissipate. Is responsible for.

[0003] As described above, since grease resistance (oil resistance) is required for automobile boots, chloroprene rubber is generally used. Chloroprene rubber does not have sufficient dynamic ozone resistance and air heat aging, so boots made from this will crack over time, causing the problem that the grease that should be covered is dissipated. . In particular, the tendency of the temperature in the engine compartment of a vehicle to increase makes this problem even more serious.

Further, chloroprene rubber absorbs grease oil sealed in the boot and causes the absorbed oil to bloom on the boot surface, so that the initial amount of grease sealed is drastically reduced, and a normal lubricating operation is performed. There is also a problem that it will not be rare. As a countermeasure for this, it is conceivable to use fluoro rubber that has excellent oil resistance, but when boots are made of fluoro rubber vulcanized molded products, the dynamic fatigue resistance and low temperature characteristics required for boots are reduced. It will be greatly impaired. As a rubber material other than these, silicone rubber excellent in heat resistance, ozone resistance and the like can be considered, but also in this case, oil resistance is inferior, and bloom of grease oil is promoted.

[0005] Furthermore, there is a permanent and potential demand for maintenance-free automobile parts, and the case of boots is no exception.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a maintenance-free automobile boot having excellent resistance to grease oil permeation.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
Hydrogenated NBR with Mooney viscosity ML _{1 + 4} (100 ℃) 50 ~ 150
Achieved by vulcanized automotive boots.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The hydrogenated NBR has a Mooney viscosity ML _{1 + 4} (100 ° C.) of about 50 to 150, preferably a moldability,
It is about 50-100 from the viewpoint of workability and the like, the amount of double bonds is about 10-0%, preferably about 5-0%, and the nitrile content is about 15-50% by weight, preferably about 25%. 4040% by weight is used. Actually, a commercially available product, for example, Zeon product manufactured by Zeon Corporation, etc. can be used as it is.

If the Mooney viscosity is higher than this, the viscosity of the rubber cloth becomes high, and in the case of a complex bellows shape such as boots, poor flow occurs, and the boots are cracked. When the rubber material having the Mooney viscosity is used, the viscosity of the rubber material is reduced, and the material sticks, so that the material storage property is greatly reduced.

The non-hydrogenated NBR is excellent in oil resistance and has no problem in grease oil permeation, but has a large amount of carbon-carbon double bonds present in the molecule, so that the dynamic resistance required for boots is high. Ozone properties will be greatly impaired. When the amount of double bonds is about 10% or more,
As in the case of NBR, the dynamic ozone resistance is greatly reduced,
The function as a boot will not be satisfied.

On the other hand, when the nitrile content is about 50% by weight or more, the composition is no longer rubbery and the low-temperature properties are significantly deteriorated.
Boots no longer satisfy low-temperature performance, while about 15% by weight
In the following, the oil resistance of the rubber itself is remarkably reduced, the rubber elasticity is also lost, the permeation amount of the grease oil is increased, and the dynamic fatigue resistance is also reduced.

In the vulcanization molding of hydrogenated NBR into boots, compounding agents known per se, such as vulcanizing agents, cross-linking assistants, reinforcing agents, fillers, and softening, may be used depending on their processability and required performance. Agents, metal activators, antioxidants, processing aids and the like are appropriately compounded.

As the vulcanizing agent, any of sulfur, a sulfur donating compound, and an organic peroxide can be used.

Examples of the sulfur-donating compound include thiurams such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, N-cyclohexyl-2-benzothiazylsulfenamide, dibenzo Thiazoles such as thiazyl disulfide and mercaptobenzothiazole are exemplified.

The organic peroxides include dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, and 2,5-dimethyl-2,5-di (tert-butylperoxy). (3-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (benzoylperoxy) hexane, di-tert-butyl peroxide, di-tert-butyl
Tributyl peroxy-3,3,5-trimethylcyclohexane and the like are used.

When an organic peroxide is used as the vulcanizing agent, it is preferable to use a crosslinking assistant together. As a crosslinking aid, sulfur, p-quinone dioxime, polyethylene glycol dimethacrylate, diallyl phthalate, triallyl cyanurate, divinylbenzene, a maleimide compound and the like are used.

As the reinforcing agent, for example, SRF, GPF,
FEF, MAF, HAF, ISAF, SAF, FT, M
Various carbon blacks such as T, finely divided silica, and the like are used. As the filler, for example, soft or heavy calcium carbonate, talc, clay and the like are used. These reinforcing agents and fillers are used in a proportion of about 5 to 200 parts by weight, preferably about 30 to 150 parts by weight, per 100 parts by weight of hydrogenated NBR.

As the softener, for example, process oil,
Lubricating oil, paraffin, liquid paraffin, petroleum asphalt, coal tar, petroleum substances such as petrolatum, castor oil, linseed oil, rapeseed oil, fatty oil such as coconut oil, tall oil, waxes, dioctyl phthalate, dioctyl adipate, dioctyl Ester plasticizers such as sebacate, liquid polybutadiene, and the like are used.

Examples of the metal activator include magnesium oxide, zinc oxide, lead tan, litharge, calcium oxide and the like. These are used in an amount of about 3 to 20 per 100 parts by weight of hydrogenated NBR.
Parts by weight, preferably about 5 to 15 parts by weight.

Examples of the anti-aging agent include aromatic secondary amine-based stabilizers such as phenylnaphthylamine and N, N-di-2-naphthyl-p-phenylenediamine, dibutylhydroxytoluene, tetrakis [methylene (3,5- At least one phenolic stabilizer such as di-tert-butyl-4-hydroxy) hydrocinnamate] methane, a metal dithiocarbamate-based stabilizer such as nickel dibutyldithiocarbamate, and an imidazole-based stabilizer are used.

The processing aids include stearic acid,
Palmitic acid, lauric acid, calcium stearate,
Higher fatty acids such as barium stearate and zinc stearate, metal salts thereof, and esters of these higher fatty acids are used.

The preparation of the hydrogenated NBR composition to which these necessary additives are added is carried out by using a kneader or a Banbury mixer to prepare each component except for a vulcanizing agent and a crosslinking aid, for about 80 to 12 parts.
After kneading at a temperature of 0 ° C. for about 3 to 10 minutes, a vulcanizing agent and a crosslinking aid are added, and the mixture is kneaded for about 5 to 30 minutes using a roll, and the prepared composition is a sheet. It is discharged as a shape or a ribbon.

The discharged sheet or ribbon is pressed using a press molding machine or an injection molding machine at a mold temperature of about 150 to 250.
The composition is vulcanized and formed into boots at a temperature of about 1 to 30 minutes.

[0024]

The automotive boot according to the present invention is not only excellent in heat aging resistance, dynamic ozone resistance and dynamic fatigue resistance, but also very excellent in grease oil permeation resistance. As described above, since grease leakage (breakage, bleeding from the seal portion) and ozone damage can be permanently dealt with, excellent performance corresponding to maintenance-free is exhibited.

[0025]

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

Example 1 Hydrogenated NBR [Zetpol 2020L manufactured by Nippon Zeon; 100 parts by weight CN content 36%, ML _{1 + 4} (100 ° C.) 57.5, iodine value 28] FEF carbon black 30 {zinc oxide 5} stearic acid 1 〃 N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine 2 〃 dibutyl carbitol adipate 10 0.5 sulfur 0.5 テ ト ラ tetramethylthiuram disulfide 2 〃 N-cyclohexyl-2-benzothiazyl sulfenamide 1 内 Among the above components, each component excluding the vulcanizing agent and the crosslinking aid is kneaded with a 3 L kneader for 5 minutes, and the discharged kneaded material is wound around a 10-inch open roll, and the remaining vulcanizing agent and the crosslinking aid are removed. The agent was charged, kneaded for 10 minutes, and cut into a sheet and a ribbon.

The sheet is put into an 80 ton press rubber compression molding machine to produce a 200 × 100 × 2 mm test piece, and the ribbon is put into a rubber injection molding machine with a mold clamping pressure of 100 ton. Then, the boot was vulcanized and formed. Each mold temperature is
180 ° C, vulcanization time is 5 minutes.

Example 2 In Example 1, another hydrogenated NBR [Zetpol 2010L manufactured by Nippon Zeon; CN content 36%, ML _{1 + 4} (100 ° C.) 85, iodine value 11] was used.

Example 3 In Example 1, another hydrogenated NBR [Zetpol 3010L manufactured by Zeon Corporation; CN content 25%, ML _{1 + 4} (100 ° C.) 95, iodine value 15] was used.

Example 4 In Example 1, instead of tetramethylthiuram disulfide and N-cyclohexyl-2-benzothiazylsulfenamide, 3 parts by weight of an organic peroxide (Nippon Oil & Fat Products Parkmill D; 50%) and 2 parts by weight of liquid polybutadiene (Nippon Soda product B-3000) was used.

Comparative Example 1 Chloroprene rubber (Showa Denko S-40) 100 parts by weight Zinc oxide 5 マ グ ネ シ ウ ム Magnesium oxide 4 〃 FEF carbon black 60 ジ オ Dioctyl sebacate 25 〃 N- (1,3-dimethylbutyl) -N ′ -Phenyl-p-phenylenediamine 3 〃 Ethylenethiourea 2 〃 Tetramethylthiuram disulfide 1 シ ー ト Sheets and ribbons are cut out using the above components, test pieces are made using them, and boots are vulcanized. Performed as in Example 1. However, the kneading time in the 3L kneader was changed to 15 minutes.

COMPARATIVE EXAMPLE 2 100 parts by weight of silicone rubber (DY32-765U, manufactured by Dow Corning Toray Co., Ltd.) Organic peroxide (Park Mill D) 1 {FEF carbon black 10} Each of the above components was kneaded with a 10-inch open roll for 10 minutes. Then, the test piece was cut out into a sheet shape and a ribbon shape, and a test piece was produced using the cut shape and a boot was vulcanized and formed in the same manner as in Example 1.

With respect to the test pieces and boots obtained in each of the examples and comparative examples, the following items were measured. Vulcanization properties: Conforms to JIS K-6301 Heat aging resistance: Change in vulcanization properties after 120 hours at 120 ° C (rate) Dynamic ozone resistance: Ozone concentration 50pphm, elongation 0-30%, 500
Measured under time conditions Dynamic fatigue resistance: Measured under conditions of elongation rate 50%, 300 times / minute Grease oil permeability: 100 ° C, 5deg. Measure the amount of grease permeated 500 hours after

The results obtained are shown in the following table. In all cases, the results of dynamic fatigue resistance were 2,000,000 times or more.

TableExample Comparative example  Measurement item 1 2 3 4 1 2 Vulcanization properties Hardness (JIS A) 60 60 55 60 60 50 Tensile strength (MPa) 29 28 27 30 17 7.4 Elongation (%) 630 780 720 510 420 250 Heat aging Hardness change (pts) +3 +2 +2 +4 +7 +1 Change in tensile strength (%) -13 +19 -14 +2 -15 -3 Change in elongation (%) -28 -27 -26 -4 -31 +2 Dynamic ozone resistance Presence or absence of cracks No No No No No Yes No (320 hours, C-1) Grease oil permeability Permeation amount (g) 0.0 0.0 0.0 0.0 1.4 1.8 Bleed No No No No Yes Yes

Claims (1)

[Claims] 1. An automotive boot vulcanized from hydrogenated NBR having a Mooney viscosity ML _{1 + 4} (100 ° C.) of 50 to 150.