JPH0543724A - Boot made of rubber - Google Patents

Abstract

PURPOSE:To obtain boots made of rubber, excellent in weather, oil and abrasion resistance and useful as drive shaft boots, etc., by molding rubber as a main base rubber, subjecting the surface to halogenating treatment and coating the resultant surface with A modified nylon, etc., to a prescribed thickness. CONSTITUTION:The objective boots made of rubber are obtained by using rubber such as natural rubber or isoprene rubber having unsaturated bonds in the molecular structure as a main base rubber, molding boots, subjecting the resultant boots to halogenating treatment with an inert gas such as nitrogen gas containing, e.g. 10-50vol.% fluorine gas and subsequently coating the treated surface with a modified nylon such as N-methoxymethylated nylon and/or polyurethane to 1-100mum thickness. A lubricant such as a silicone oil is preferably contained in the coated modified nylon and/or polyurethane film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to rubber boots to which forces in various directions are frequently applied. In particular,
The present invention relates to automobile rack and pinion boots, drive shaft boots, and the like. It can also be applied to rubber bellows used under harsh conditions and rubber covers.

[0002]

2. Description of the Related Art A general rubber bellows, that is, a bellows which is not particularly severely used, uses inexpensive natural rubber or styrene-butadiene rubber as a base rubber. However, automobile rack and pinion boots and drive shaft boots use chloroprene rubber as a base rubber. These are often mounted near the bottom of the car. For this reason, he is always exposed to rain and wind. Also, if you drive on a rainy day, oil will be attached to the road surface. For these reasons, chloroprene rubber, which has excellent weather resistance and oil resistance, is the base rubber. Recently, polyester-based elastomers (such as Hytrel from DuPont) are also used. Although this elastomer is expensive, it has high weather resistance and oil resistance, and is suitable for rack and pinion boots.

Rubber boots such as rack-and-pinion boots and drive shaft boots have a bellows shape in order to cope with a severe vibration of an automobile and a twisting force applied when turning a curve. As a result, the piles of rubber boots often bump into or rub against each other. Also, it is not uncommon for road pebbles and gravel to hit the mountains. Therefore, the crests of these rubber boots are very susceptible to wear. Especially for taxis and commercial vehicles with long mileage, this part is easily damaged.

[0004]

SUMMARY OF THE INVENTION The present invention provides a rubber boot that does not easily wear even under severe use.

[0005]

The rubber boot of the present invention is manufactured as follows. Rubber boots are molded from rubber that has an unsaturated bond in its molecular structure. The surface of the rubber boot is halogenated. Coat the surface of rubber boots with modified nylon or polyurethane. This will be described in detail below.

A rubber boot is molded from rubber having an unsaturated bond in its molecular structure. A rubber boot having a desired shape is formed by using a rubber having an unsaturated bond in a molecular structure as a main base rubber. Specific examples of the rubber having an unsaturated bond in its molecular structure include natural rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, and acrylonitrile butadiene rubber. You may mix two or more kinds and use it as a base rubber. Set the composition suitable for the selected base rubber. Add a compounding agent and a crosslinking agent to the base rubber and knead. Subsequently, the rubber boot is crosslinked and molded with a mold having a desired shape. Table 1 exemplifies the composition and cross-linking conditions of the trial-made rubber boot.

[0007]

[Table 1]

The surface of the rubber boot is halogenated. The surface of the rubber boot prototyped in 1. is halogenated. The halogenation treatment includes fluorination treatment, chlorination treatment, bromination treatment, and iodination treatment, and any method may be selected.

Fluorination treatment An inert gas (nitrogen gas, argon gas, etc.) containing 10 to 50% by volume of fluorine gas is prepared. The rubber boot is exposed to this gas at room temperature for 30 minutes to 2 hours.・ Chlorination The rubber is treated in the same way as conventional rubber chlorination. For example, 2 to 7 g of the exposed powder and 3 to 9 ml of 12N hydrochloric acid are dissolved in 1 liter of water. A rubber boot is immersed in this solution at room temperature for 10 seconds to 5 minutes. -Bromination treatment, iodination treatment Bromine and iodine are sufficiently dissolved in water, and the rubber boot is immersed in this solution at room temperature for 3 to 80 minutes. When chlorination treatment, bromination treatment, or iodination treatment is adopted, after the treatment, the rubber boot is washed with a weak alkaline solution, washed with water, and dried.

The surface of the rubber boot is coated with modified nylon or polyurethane. The surface of halogenated rubber boots is coated with an elastomer having high wear resistance, weather resistance and oil resistance. Elastomers having high wear resistance, weather resistance and oil resistance include modified nylon and polyurethane. Specific examples of the modified nylon include copolymerized nylon and N-methoxymethylated nylon. These nylons are more elastic than 6-nylon and the like. Polyurethane can be either thermoplastic or thermosetting. Further, either polyester type or polyether type polyurethane may be used. Two or more types of modified nylon and polyurethane may be mixed.

These are coated on the surface of the rubber boot. It may be coated by any method. To form a thin film of modified nylon or polyurethane,
It is preferable to use a solution in which these are dissolved in a solvent.

The modified nylon contains a lower alcohol such as methanol or ethanol as a main solvent. 5 to this
Dissolve the modified nylon so as to be 50% by weight. N
-Methoxymethylated nylon crosslinks with organic acids. When it is desired to crosslink, citric acid, tartaric acid, etc. are used as a crosslinking catalyst for N-methoxymethylated nylon.
It is dissolved in a solvent so as to be 3 to 5% by weight. Polyurethane has dimethylformamide, tetrahydrofuran, dioxane and the like as a main solvent. Polyurethane is dissolved therein in an amount of 5 to 50% by weight. When a thermosetting polyurethane is used, the main agent and the curing agent may be separately dissolved in a solvent and then combined, or the main agent and the curing agent may be mixed and then dissolved.

This solution is applied to rubber boots. It may be applied by any method. For example, the solution may be sprayed onto rubber boots. Alternatively, the rubber boots may be dipped in the solution and taken out. 40 to 10 when applied
Heat at 0 ° C. for 5 minutes to 3 hours to evaporate the solvent. N-
When using methoxymethylated nylon, 120 to 1
Crosslink the N-methoxymethylated nylon by heating at 50 ° C for 5-20 minutes. When the thermosetting polyurethane is used, it is heated at 100 to 150 ° C. for 30 minutes to 10 hours to cure the polyurethane.

Further, the present inventor has devised a rubber boot in which the friction resistance of the rubber boot is reduced to improve the wear resistance. That is, the wear resistance of the rubber boot is improved by improving the slippage when the mountain portion of the rubber boot hits each other or a small stone hits. To reduce the frictional resistance, a lubricant is mixed in the film coated on the surface of the rubber boot. Suitable lubricants are chemicals such as silicone oil, stearic acid, stearamide, n-butyl stearate and higher alcohols, and powders such as molybdenum disulfide, graphite powder and Teflon powder. The amount to be mixed is 1 to 10% by weight for chemical lubricants and 10 to 1 for powder lubricants, based on the total amount of modified nylon or polyurethane coated.
It should be 00% by weight. The lubricant is dissolved or dispersed in the solvent together with the modified nylon or polyurethane.
This solution is used to coat the rubber boot surface. The coating method and the film forming method are the same as those in the case where no lubricant is added.

[0015]

In the rubber boot of the present invention, the base rubber can be selected from rubbers having unsaturated bonds, that is, a wide range of rubbers. If you use cheap natural rubber or styrene-butadiene rubber, you can make cheap rubber boots.

The surface of the rubber boot kneaded and molded with the set composition is halogenated. A rubber having an unsaturated bond in its molecular structure is selected as the base rubber, so that it can be easily halogenated. Crosslinked rubber has poor adhesion to other objects. However, when this is halogenated, a thin polar film is formed on the surface. Then, the adhesion with nylon or polyurethane becomes very high.

A modified nylon or polyurethane solution is applied to a halogenated rubber boot. If a solution of copolymerized nylon or thermoplastic polyurethane is applied,
Warm to 40-100 ° C. Then, only the solvent evaporates, and a film of copolymer nylon or polyurethane is formed on the surface of the rubber boot. 100 when applied with a solution of N-methoxymethylated nylon or thermosetting polyurethane
Heat to ~ 150 ° C. Then, the solvent is volatilized first, and then a cross-linked N-methoxymethylated nylon or polyurethane film is formed on the surface of the rubber boot. N-
When a solution of methoxymethylated nylon is applied, like the copolymerized nylon, only the solvent may be volatilized, that is, a non-crosslinked film may be formed. However, cross-linking results in higher wear resistance.

If the film on the surface of the rubber boot is not more than 1 μm, the effect as a film will not be exhibited. In addition, 100μ
If it exceeds m, the movement of the rubber boot will be hindered. Therefore, the formed film is adjusted to have a thickness of 1 to 100 μm. For the thickness, the solution coating and solvent volatilization operations are 2 to 5
It can be adjusted by repeating the operation once. If the rubber boot folds are small, use a low-concentration solution for 2-5
If the number of folds and folds is large, use a concentrated solution to
By repeating the above operation twice, a film having an appropriate thickness is obtained. A modified nylon or polyurethane solution may be applied alternately.

The modified nylon or polyurethane film thus formed has high abrasion resistance, weather resistance and oil resistance. In addition, the nylon film has a low coefficient of friction and good sliding.
When such a material hits the mountain portion of the rubber boot, it slips well and is not easily worn.

The present inventor applied this and added a lubricant to the film. A chemical such as silicone oil is dissolved in a solvent together with modified nylon or polyurethane. Powder such as Teflon powder should be well dispersed in the solvent. Using this solution, operate as if no lubricant had been added. Then, a modified nylon or polyurethane film containing a lubricant is formed on the surface of the rubber boot. Since this film contains a lubricant, it has a low frictional resistance. When forming this film, first, a film containing no lubricant is formed on the surface of the rubber boot, and then a film containing a lubricant is formed on the surface of the rubber boot.

[0021]

Example A) Example of coating a rubber boot using styrene-butadiene rubber as a base rubber with copolymer nylon. Styrene-butadiene rubber as a main base rubber is compounded as shown in Table 1 and I and kneaded. Mold the rubber boots by heating at 160 ° C. for 10 minutes. This is chlorinated. 4 g of bleached powder and 5 ml of 12N hydrochloric acid in 1 l of water
Add and mix well. Immerse rubber boots in this and
Leave for a minute. The rubber boot taken out is washed with a 1% sodium hydrogen carbonate solution, then washed with water and dried. Toray CM8000 was used as the copolymer nylon. This nylon is more elastic than 6-nylon or the like. CM80
It is dissolved in methanol so that 00 becomes about 30%.
A chlorinated rubber boot is immersed in this solution.
After about 5 seconds, it is taken out and dried at 70 ° C. for 5 minutes. This operation is repeated twice. The second time is dried at 70 ° C. for 30 minutes. Then, the friction resistance is small on the surface of the rubber boot,
A copolymer nylon film having weather resistance and oil resistance is formed. The film thickness was about 40 μm.

Example B) Example of coating rubber boot using natural rubber as base rubber with N-methoxymethylated nylon A natural rubber is used as a main base rubber and compounded as shown in Tables 1 and II and kneaded. Mold the rubber boots by heating at 160 ° C. for 10 minutes. This is fluorinated. Put rubber boots in a pressure container to eliminate air inside the container. Next, the container is filled with nitrogen gas containing 35% by volume of fluorine and left at room temperature for 1 hour. The surface of the rubber boot taken out is coated with N-methoxymethylated nylon. As the N-methoxymethylated nylon, Torayzin MF-30 manufactured by Teikoku Chemical Industry Co., Ltd. was used. Since this nylon can be crosslinked, it has particularly high elasticity among nylons. Dissolved in methanol is about 25% of resin MF-30 and about 1% of tartaric acid as a crosslinking catalyst. The rubber boot is dipped in this solution and pulled up after 5 seconds. It is dried at 80 ° C. for 5 minutes. After repeating this operation twice, it is heated at 120 ° C. for 15 minutes to cross-link the N-methoxymethylated nylon. Then, an N-methoxymethylated nylon film which is elastic and hard to wear is formed on the surface of the rubber boot. The film thickness was about 30 μm.

Example C) Example in which a rubber boot whose main base rubber is butadiene rubber is coated with thermosetting polyurethane. Tables I and II using butadiene rubber as the main base rubber.
Mix as in I and knead. Mold the rubber boots by heating at 160 ° C. for 10 minutes. The surface is chlorinated as in Example A. As the thermosetting polyurethane, Takenate L-1270 manufactured by Takeda Pharmaceutical Co., Ltd. was used. Dissolve the takenate in tetrahydrofuran at about 15%.
Immerse the rubber boots in this, take out after 10 seconds,
Dry at 80 ° C. for 10 minutes. After repeating this operation again, it is heated at 110 ° C. for 5 hours to crosslink the polyurethane. Then, a polyurethane film having elasticity and being hard to wear is formed on the surface of the rubber boot. The film thickness is about 2
It was 5 μm.

Example D) Example in which a rubber boot whose main base rubber is butadiene rubber is coated with thermoplastic polyurethane containing silicone oil. A rubber boot similar to that of Example C is molded using butadiene rubber as the main base rubber. , Chlorinate the surface. As the thermoplastic polyurethane, Paraprene 26 manufactured by Nippon Polyurethane Industry Co., Ltd. was used. The paraprene 26 is dissolved in tetrahydrofuran so as to be about 15%. Immerse the rubber boots in this solution, take out after 10 seconds,
Dry for minutes. Next, Paraprene 26 is about 15%, silicone oil (Toray Dow Corning Silicone Co., Ltd.)
A solution dissolved in tetrahydrofuran is prepared so that SH200 1000 cs) is about 0.3%. Immerse the rubber boots in this solution, remove after 10 seconds,
Dry at 80 ° C. for 30 minutes. Then, on the surface of the rubber boot, a polyurethane film having elasticity and wear resistance and low friction resistance is formed. The thickness of this film is about 2
It was 0 μm.

(Experiment) The wear resistance and weather resistance of the above-described examples were tested. A rubber sheet having a film formed thereon in exactly the same manner as in Examples A to D (width 5 cm, length 25 c
m, thickness 0.3 cm) was prepared and used as an experimental sample. As a control, a chloroprene rubber was used as a base rubber, and a rubber sheet molded in the same size was used. The existing rack-and-pinion boot uses chloroprene rubber as the base rubber, so a rubber sheet of chloroprene rubber was used as a control. Next, the test method will be described. Abrasion resistance: Square weight made of stainless steel (width 2 cm, length 5 cm, weight 1
(kg) on a rubber sheet. In the direction of the long axis,
Reciprocate. The length of the reciprocating motion is 20 cm, and the reciprocating motion is performed once per second, and the surface state of the sample is observed after 5 hours. Weather resistance: In an ozone atmosphere with a concentration of 1 ppm (25
(° C), leave the rubber sheet. The surface of the rubber sheet is observed after 48 hours.

The results of visual observation were evaluated on a 5-point scale.
The results are shown in Table 2. Regarding the wear resistance, all the samples prepared by the method of the present invention showed higher wear resistance than the samples of chloroprene rubber. In particular, the sample having silicone oil added to form a film (Example D) had high wear resistance. Regarding the weather resistance, all the samples prepared by the method of the present invention had weather resistance equal to or higher than that of the chloroprene rubber sample. Only 1 to 10 for rubber sheets of natural rubber and styrene-butadiene rubber
It can be seen that by forming a modified nylon or polyurethane film having a thickness of 0 μm, the abrasion resistance and the weather resistance were higher than those of the chloroprene rubber sheet. From this result, it can be said that the weather resistance and wear resistance of the rubber boot of the present invention are superior to those of the current chloroprene rubber boot.

[0027]

[Table 2]

[0028]

[Effect] The rubber boot of the present invention is obtained by coating the surface of a rubber molded product with copolymer nylon or polyurethane in a thickness of 1 to 100 μm. Since the copolymerized nylon and polyurethane have elasticity, these films do not impede the movement of the rubber boot. In addition, the movement of the rubber boot does not cause these films to break. Copolymer nylon and polyurethane have high abrasion resistance in addition to weather resistance and oil resistance.
By coating these on the rubber boot, the weather resistance, oil resistance, and abrasion resistance of the rubber boot can be improved. The nylon film has a low frictional resistance and thus slides well, and this aspect also imparts abrasion resistance to the rubber boot.

Since the coated film of copolymerized nylon or the like bears weather resistance, oil resistance and abrasion resistance, the rubber molded product itself is not particularly required to have these properties. Therefore, although the base rubber lacks weather resistance, oil resistance, and abrasion resistance, inexpensive natural rubber or styrene-butadiene rubber can be used. Rubber boots using these as the base rubber have weather resistance and oil resistance equal to or higher than those of the rubber boots using chloroprene rubber as the base rubber by coating copolymer nylon etc., and have far superior wear resistance. It can be a rubber boot with.

The addition of a lubricant in the coating reduces the frictional resistance of the rubber boot surface. This allows the rubber boots to skid well when bumped against each other or against other hard objects. Therefore, this rubber boot is a rubber boot that is less likely to wear. In this way, the rubber boot of the present invention, even when used severely,
Rubber boots that can be used for a long time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B32B 7/02 7188-4F 25/08 9155-4F 27/18 Z 6122-4F 27/34 27 / 40

Claims (2)

[Claims] 1. A boot is formed by using a rubber having an unsaturated bond in a molecular structure as a main base rubber, the surface of the boot is halogenated, and a modified nylon or / and polyurethane is coated thereon with a thickness of 1 to 100 μm. Rubber boots characterized by doing. 2. A coated modified nylon or /
The rubber boot according to claim 1, wherein a lubricant is included in the polyurethane film.