JP2002226617A - Component of weather-resistant rubber elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a component of weather-resistant rubber elastomer accepting dynamic deformation, which has excellent ozone deterioration resistance and good durability. SOLUTION: The component of weather-resistant rubber elastomer is composed by coating a surface of the component of rubber elastomer accepting dynamic deformation with a thermoplastic elastomer film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weather-resistant rubber elastic member, and more particularly, to a wheel-mounted elastic member, a seismic isolation rubber member, and a vibration-proof rubber member having particularly excellent resistance to ozone deterioration and excellent durability. The present invention relates to a weather-resistant rubber elastic member which undergoes dynamic deformation such as a vibration damping rubber member and a fender.

[0002]

2. Description of the Related Art Conventionally, rubber elastic bodies having a double bond in the molecule, for example, natural rubber, styrene-butadiene rubber (S
BR), polybutadiene rubber (BR), synthetic isoprene rubber (IR), acrylonitrile-butadiene rubber (N
It is known that BR) and the like are susceptible to deterioration by ozone and are easily cured or cracked. Therefore, in order to suppress such deterioration due to ozone, a countermeasure has been taken so far by blending a rubber material. in this case,
There are two aspects, namely, improvement of static (state without distortion) ozone resistance, and improvement of dynamic (state where distortion changes) ozone resistance. The former improvement of static ozone resistance generally includes: Waxes are used. The waxes bloom on the surface of the single rubber member after vulcanization, shut off the surface from air, reflect sunlight, and exert its effect.

[0003] However, although these waxes are effective for improving static ozone resistance, cracks are liable to occur in the wax layer on the surface formed by blooming in a member that repeatedly elongates and bends. As a result, there is a disadvantage that the effect of the ozone resistance is impaired. Therefore, the waxes are not effective in improving dynamic ozone resistance. Therefore, in order to improve the dynamic ozone resistance, a rubber material generally has ethylene-propylene rubber (EP) having no double bond in the molecule or having a low content even if it has a double bond.
M), ethylene-propylene-diene rubber (EPD)
M) and an antiozonant such as N-
Isopropyl-N'-phenyl-p-phenylenediamine (3C), N- (1,3-dimethylbutyl) -N'-
Mixing of phenyl-p-phenylenediamine (6C), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (AW) and the like has been performed. However, such compounding of EPM and EPDM inevitably reduces the degree of freedom in rubber design, and causes other problems such as deterioration of other characteristics such as repeated durability.

[0004] In order to improve the resistance to ozone deterioration of a rubber elastic member subjected to dynamic deformation, conventionally, as described above, a measure is taken by compounding a rubber component. There is no known example of providing a film. This is because even if an ozone-resistant coating film is provided, it is thought that when the coating film undergoes dynamic deformation such as elongation or bending, the coating film is cracked and the ozone resistance effect is not sufficiently exerted. Seem. On the other hand, thermoplastic elastomers having properties intermediate between rubber and plastic are known. This thermoplastic elastomer has both a rubber component having elasticity in the molecule, that is, a soft segment, and a molecular constraint component for preventing plastic deformation, that is, a hard segment. Have been put to practical use and are used in a wide range of fields.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a rubber elastic member which undergoes dynamic deformation under such circumstances,
It is an object of the present invention to provide a rubber elastic member having excellent resistance to ozone deterioration and excellent durability without impairing the inherent properties of the rubber elastic body itself and the degree of freedom in rubber design.

[0006]

The inventor of the present invention has made intensive studies to develop a rubber elastic member having the above-mentioned excellent properties and undergoing dynamic deformation. It has been found that the object can be achieved by providing a thermoplastic elastomer-based coating film on the surface of. The present invention has been completed based on such findings. That is, the present invention provides a weather-resistant rubber elastic member having a thermoplastic elastomer-based coating film on the surface of the rubber elastic member that undergoes dynamic deformation.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the weather-resistant rubber elastic member of the present invention, the rubber elastic member which undergoes dynamic deformation may be any rubber elastic member which repeatedly undergoes dynamic deformation such as elongation or bending. There is no particular limitation, and preferred examples include a wheel-mounted elastic member, a seismic isolation rubber member, an anti-vibration / damping rubber member, and a fender. As the rubber material constituting the rubber elastic member subjected to the dynamic deformation,
There is no particular limitation, various things can be used,
From the viewpoint that the effects of the present invention are effectively exhibited, those having a double bond in the molecule, such as natural rubber, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), synthetic isoprene rubber (IR), acrylonitrile- Butadiene rubber (NBR) is preferred. These may be used alone or in a combination of two or more.

[0008] The rubber elastic member subjected to the dynamic deformation,
For example, in the rubber component, various compounding agents usually used in the rubber industry, specifically, reinforcing materials such as carbon black and silica, vulcanizing agents, vulcanization accelerators, aging prevention against heat, oxygen, ozone, light, etc. , A scorch inhibitor, zinc white, stearic acid, etc. are blended to prepare a rubber composition, which is then molded into a desired shape, and then vulcanized.
Can be made. In the present invention, a thermoplastic elastomer-based coating film is provided on the surface of the rubber elastic member thus subjected to dynamic deformation. The thermoplastic elastomer constituting the coating film is not particularly limited, but preferably has no double bond in the molecule from the viewpoint of resistance to ozone deterioration. For example, a polyolefin-based, polystyrene-based, polyurethane-based, or polyester-based elastomer is preferred. And polyamide-based thermoplastic elastomers.
Here, as the polyolefin-based thermoplastic elastomer, for example, those using a polyolefin such as polyethylene or polypropylene for the hard segment and using EPM or EPDM for the soft segment can be preferably exemplified. Examples of the polystyrene-based thermoplastic elastomer include hydrogenated styrene-butadiene-styrene block copolymer (SEBS) and hydrogenated styrene-
Preferable examples include isoprene-styrene block copolymer (SEPS). In this case, the styrene block portion becomes a hard segment, and the hydrogenated butadiene block portion and the hydrogenated isoprene block portion become soft segments.

The polyurethane-based thermoplastic elastomer is
A polymer chain composed of a diisocyanate component and a short-chain glycol is used as a hard segment, and a polymer chain composed of a diisocyanate component and a polyol component is used as a soft segment. (1) Polylactone ester polyol obtained by ring-opening of caprolactone, (A) a type obtained by addition-polymerizing a diisocyanate in the presence of a short-chain polyol, (2) a type obtained by addition-polymerizing a diisocyanate to an adipic acid ester polyol obtained from adipic acid and a glycol, and ( 3) Polytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran can be classified into a type obtained by addition polymerization of diisocyanate in the presence of a short-chain polyol. As the polyester-based thermoplastic elastomer, an amorphous polyester having a high melting point and a high crystalline aromatic polyester such as polybutylene terephthalate as a soft segment and having a glass transition temperature of −70 ° C. or lower, such as polytetramethylene ether glycol Or a block copolymer having an aliphatic polyester as a soft segment.

Examples of the polyamide-based thermoplastic elastomer include a block copolymer having a hard segment of nylon 6, nylon 11, nylon 12, or the like and a soft segment of a polyol such as polyester or polytetramethylene glycol. As the thermoplastic elastomer, besides these, a polyvinyl chloride-based thermoplastic elastomer and a fluororesin-based thermoplastic elastomer can also be used. In the present invention, one or a combination of two or more of these thermoplastic elastomers is used and dissolved in an appropriate organic solvent to prepare a coating liquid for forming a thermoplastic elastomer-based coating film.
At this time, if necessary, various known additives such as antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, surfactants,
An antifoaming agent, a leveling agent, a coloring agent and the like can be added. The viscosity of the coating liquid is not particularly limited as long as it is a viscosity that allows application.

In the present invention, before the coating liquid is applied to the surface of the rubber elastic member which is subject to dynamic deformation, the rubber elastic member is preliminarily formed in order to enhance the adhesion to a coating film to be formed. Can be subjected to a physical or chemical surface treatment such as an oxidation method or a roughening method. As the oxidation method,
For example, corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone and ultraviolet irradiation treatment, and the like,
Examples of the unevenness method include a sand blast method and a solvent treatment method. These surface treatment methods are appropriately selected depending on the type of the rubber elastic member. There is no particular limitation on the application method, and various known methods such as brushing,
From the methods such as tampo coating, air spray coating, airless spray coating, hot spray coating, roller coating, curtain flow coating, flow coating, and dipping (dipping), select an appropriate method according to the situation. Can be. In addition, it may be finished with a single application, or may be applied multiple times as needed. In the case of coating a plurality of times, the same coating liquid may be used, or different types of thermoplastic elastomers may be used.

After the coating liquid is applied to the surface of the rubber elastic member in this manner, natural drying or heat drying is performed, and then, if necessary, baking drying treatment is performed to obtain a desired thermoplastic elastomer-based coating film. Is formed. If the thickness of this coating film is too thin, the anti-ozone deterioration resistance may be insufficient, and if it is too thick, when the rubber elastic member repeatedly undergoes dynamic deformation, it may cause cracks. Become. Therefore, the preferable thickness of the coating film is in the range of 1 to 100 μm, and particularly preferably in the range of 5 to 50 μm. In this manner, a weather-resistant rubber elastic member having a thermoplastic elastomer-based coating film on the surface of the rubber elastic member subjected to dynamic deformation and having excellent resistance to ozone deterioration can be obtained.

[0013]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The test samples obtained in each example were evaluated for static ozone resistance, dynamic ozone resistance and repeated durability according to the following procedures. (1) Static ozone resistance In accordance with JIS K6259 rubber ozone deterioration test method, elongation 30%, ozone concentration 50ppm, temperature 40
The time until cracks were generated under the condition of ° C. was determined and evaluated as static ozone resistance. (2) Dynamic ozone resistance According to the ozone deterioration test method for rubber according to JIS K6259, elongation rate ± 30%, ozone concentration 50 pphm, temperature 4
The time until cracking occurred at 0 ° C. was determined and evaluated as dynamic ozone resistance. (3) Repetition durability The test sample having the shape shown in FIG.
The rubber part 2 having the described shape and dimensions is bonded, and the unit of the number is mm. ), In a 40 ° C. atmosphere, giving a constant strain repetitive vibration of 0 ± 70% (3 Hz) in the shear direction,
The number of times until cracks were generated was determined and evaluated as repeated durability.

Comparative Example 1 100 parts by weight of natural rubber, 30 parts by weight of FEF carbon black, 2 parts by weight of stearic acid, 5 parts by weight of zinc white,
2 parts by weight of microcrystalline wax, antioxidant 6
C [N- (1,3-dimethylbutyl) -N'phenyl-
p-Phenylenediamine], 2 parts by weight of sulfur, and 1.5 parts by weight of a vulcanization accelerator CBS (N-cyclohexyl-2-benzothiazylsulfenamide) were prepared to prepare a rubber composition. After this rubber composition was formed into a desired shape, it was vulcanized at 155 ° C. for 15 minutes to prepare a sample for a static ozone resistance evaluation test and a sample for a repeated durability evaluation test. went. The results are shown in Table 1.

Example 1 A vulcanized molded product having a desired shape was obtained in the same manner as in Comparative Example 1, and a polyolefin-based thermoplastic elastomer coating solution “SOFLEX 6000 Primer” [manufactured by Kansai Paint Co., Ltd.] ] And sprayed at 120 ° C. for 30 minutes to form a 10 μm-thick polyolefin-based thermoplastic elastomer coating film. A sample for a static ozone resistance evaluation test and a sample for a repeated durability evaluation test were prepared. Produced. An evaluation test was performed for each, and the results are shown in Table 1.

Example 2 In the same manner as in Comparative Example 1, a vulcanized molded article having a desired shape was obtained, and then a polyurethane-based thermoplastic elastomer coating liquid “Softop L800” [China Paint Co., Ltd. Two-component type] is spray-coated and subjected to a forced drying treatment at 60 ° C. for 2 hours to provide a 10 μm-thick polyurethane-based thermoplastic elastomer coating film, a sample for static ozone resistance evaluation test and a repeated durability evaluation test Was prepared for use. An evaluation test was performed for each of them, and the results are shown in Table 1.

Example 3 A vulcanized molded product having a desired shape was obtained in the same manner as in Comparative Example 1, and a polystyrene-based thermoplastic elastomer coating solution “PROT (proto: oily)” [imported and sold:
Office Sho] was dip-coated and dried at room temperature for 24 hours to form a 40 μm-thick polystyrene-based thermoplastic elastomer coating film. A sample for a static ozone resistance evaluation test and a repeated durability evaluation test Was prepared for use. An evaluation test was performed for each of them, and the results are shown in Table 1.

Comparative Example 2 Evaluation of static ozone resistance was carried out in the same manner as in Comparative Example 1 except that a mixture of 70 parts by weight of natural rubber and 30 parts by weight of EPDM was used instead of 100 parts by weight of natural rubber as a rubber component. A test sample and a sample for a repeated durability evaluation test were prepared, and an evaluation test was performed on each of them. The results are shown in Table 1.

[0019]

[Table 1]

[0020]

According to the present invention, by providing a thermoplastic elastomer coating on the surface of a rubber elastic member which undergoes dynamic deformation, the inherent properties of the rubber elastic body itself and the degree of freedom in rubber design are impaired. Without this, it is possible to obtain a rubber elastic member having excellent resistance to ozone deterioration and good durability.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the shape of a test sample for a repeated durability test in Examples and Comparative Examples.

[Explanation of symbols]

 1: Seismic rubber fitting 2: Rubber part

 ──────────────────────────────────────────────────続 き Continued from the front page F term (reference) 4F006 AA04 AA12 AA15 AA35 AA37 AA38 BA03 CA04 DA04 4F100 AK03B AK12B AK41B AK46B AK51B AL09B AN00A BA02 EH462 GB31 JB16B JH02 JK07A JL09 JM1B01J051J051J051M PB07 PC07

Claims (6)

[Claims] 1. A weather-resistant rubber elastic member having a thermoplastic elastomer coating film on a surface of a rubber elastic member that undergoes dynamic deformation. 2. The weather-resistant rubber elastic member according to claim 1, wherein the rubber elastic member subjected to dynamic deformation is a wheel-mounted elastic member, a seismic isolation rubber member, a vibration-proof / damping rubber member, or a fender. 3. The weather-resistant rubber elastic member according to claim 1, wherein the rubber material in the rubber elastic member subjected to dynamic deformation is a rubber elastic member having a double bond in a molecule. 4. The weather-resistant rubber elastic member according to claim 1, wherein the thermoplastic elastomer-based coating film contains a polyolefin-based, polystyrene-based, polyurethane-based, polyester-based, or polyamide-based thermoplastic elastomer. 5. A thermoplastic elastomer-based coating film having a thickness of 1
The weather-resistant rubber elastic member according to any one of claims 1 to 4, wherein the thickness is from 100 to 100 µm. 6. The weather-resistant rubber elastic member according to claim 1, which is resistant to ozone deterioration (rubber elastic member).