JP3171206B2 - Processing method of hydrophilic vulcanized rubber molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for treating a hydrophilic vulcanized rubber molded article having excellent surface hydrophilicity and lubricity.

[0002]

2. Description of the Related Art Conventionally, methods for hydrophilizing polymer materials include: 1. A method of graft copolymerizing a hydrophilic resin to a polymer molding material (for example, JP-A-49-125493). A method has been proposed in which free radicals are generated on the surface of a molded polymer material in the presence of a polymerization regulator to cause a water-soluble monomer to act (for example, JP-A-62-87163). However, these conventional techniques require complicated processes such as radiation treatment, plasma treatment, and discharge treatment. In addition, when the organic peroxide treatment is performed, there is a problem that the hydrophilicity and lubricity of the surface deteriorate with time.

[0003]

An object of the present invention is to solve the above-mentioned problems of the prior art, to simplify the manufacturing process, and to treat a hydrophilic vulcanized rubber molded product with less deterioration of the hydrophilicity and surface lubricity of rubber with time. Is the way.

[0004]

The method for treating a hydrophilic vulcanized rubber molded product according to the present invention comprises:
An unvulcanized rubber molded product containing an organic peroxide is brought into contact with a hydrophilic radically polymerizable monomer and heated at a temperature not lower than the active point of the organic peroxide. Specifically, a method in which an unvulcanized rubber molded product containing an organic peroxide is brought into contact with a vapor of a hydrophilic radically polymerizable monomer and heated at a temperature equal to or higher than the active point of the organic peroxide, The method is carried out by immersing an unvulcanized rubber molded product containing an organic peroxide in a solution of the radical polymerizable monomer, and heating at a temperature not lower than the active point of the organic peroxide.

Hereinafter, the reaction materials and reaction conditions used in the present invention will be specifically described. The unvulcanized rubber molded article containing the organic peroxide used in the present invention is: 1. An unvulcanized rubber compounded with an organic peroxide and molded, or After the organic peroxide was added to the unvulcanized rubber, it was partially vulcanized.However, the organic peroxide that could contribute to vulcanization remained in the unvulcanized rubber, and vulcanization was possible. It refers to a part of vulcanized rubber molded.

In the present invention, since the vulcanization and the hydrophilization of an unvulcanized rubber molded product containing at least a part of the unvulcanized organic peroxide as described above are performed simultaneously, the hydrophilic polymerizable monomer is used. The grafting reaction can sufficiently react on the rubber surface and in the vicinity of the rubber surface, so that not only the advantage that hydrophilization and vulcanization can be performed in one step but also the hydrophilic vulcanized rubber molding obtained by the present invention can be achieved. Things are
The surface can be made hydrophilic without changing the excellent properties of the base material, and the excellent effect that the deterioration of the hydrophilicity with time is small is exhibited. Examples of unvulcanized rubber include silicone rubber, natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, butyl rubber, ethylene propylene rubber, ethylene vinyl acetate copolymer, chloroprene rubber, chlorinated polyethylene, nitrile rubber, urethane rubber , Fluoro rubber and the like, but the present invention is not limited to these. These unvulcanized rubbers
It can be in the form of molded articles of any shape, for example, chips, fibers, films and the like.

As the organic peroxide to be blended in the unvulcanized rubber molded product, any organic peroxide generally used as a vulcanizing agent can be used without any particular limitation. For example, 2,4-
Examples thereof include dichlorobenzoyl peroxide (DCBPO), benzoyl peroxide (BPO), di-t-butyl peroxide, dicumyl peroxide, and t-butyl perbenzoate. The amount of these organic peroxides is determined in consideration of the desired degree of vulcanization, but it is usually preferable to add about 0.1 to 2.0% by weight. More preferably, 1.5 to 2.0% by weight
It is particularly preferable to mix them to a certain degree.

Examples of the hydrophilic radical polymerizable monomer include, but are not limited to, acrylamide, vinylpyrrolidone, methacrylamide, acrylic acid, 2-hydroxyethyl methacrylate and the like. .

An unvulcanized rubber molded product containing an organic peroxide is brought into contact with a vapor of a hydrophilic radically polymerizable monomer,
When heating at a temperature equal to or higher than the active point of the organic peroxide, for example, an unvulcanized rubber molded product in which a solution of a hydrophilic radically polymerizable monomer is vaporized and an organic peroxide is blended in the vapor And a method in which the vapor of a hydrophilic radically polymerizable monomer is diluted with an appropriate inert gas (eg, nitrogen) and supplied to contact an unvulcanized rubber molded product containing an organic peroxide. Can be As another method, an unvulcanized rubber molded article containing an organic peroxide is immersed in a solution of a hydrophilic radically polymerizable monomer, and heated at a temperature equal to or higher than the active point of the organic peroxide. There is a way. In the production method of the present invention, when the hydrophilic radical polymerizable monomer is used after being diluted with a solvent, the solvent is water-soluble, and the organic peroxide compounded in the unvulcanized rubber molded product is used. It is not particularly limited as long as it has a boiling point higher than the active point and does not excessively swell the unvulcanized rubber molded product. Preferably, water is used, but organic solvents miscible with water can also be used. As the organic solvent, one that dissolves rubber cannot be used, but one that swells can be used. Examples of such an organic solvent include ethyl alcohol. Further, the concentration of the hydrophilic radical polymerizable monomer is preferably about 5 to 20% by weight from the reason of the effect of imparting hydrophilicity.

The heating temperature is not particularly limited as long as it is a temperature not lower than the active point of the organic peroxide to be used.
Further, the treatment time is appropriately determined in consideration of the type of the unvulcanized rubber molded product and the radical polymerizable monomer to be used or the degree of hydrophilicity and vulcanization.

[0011]

EXAMPLES Example 1 (1) Preparation of Test Specimen According to the Present Invention 2% by weight of DCBPO was blended into unvulcanized silicone rubber * ¹ , rolled, and then cold pressed to 12%.
Performed for a time to obtain a substrate. This substrate is made of acrylamide 10
wt% aqueous solution (100 ° C / 10
Boiled for at least 3 minutes to remove dissolved oxygen), heated at 95 ° C for 3 minutes, washed with ion-exchanged water for 10 minutes, and then heated in air at 160 ° C for 5 hours. Processing was performed. Then, it was washed with ion-exchanged water and further dried to obtain a test piece A. Note) * ¹ Compounded with silica in vinyl silicone rubber. (2) Preparation of Test Specimen of Comparative Example 2% by weight of DCBPO was blended with condensable room temperature-curable rubber * ² and cured at room temperature for 24 hours. The test piece B of the comparative example was treated with a 10 wt% aqueous solution of acrylamide, and further washed, heated, washed and dried in the same manner as in the preparation of the test piece of the example.
And Note) * Consists of a ^2- condensation type silicone rubber and a condensation catalyst. Example 2 After measuring the contact angle and the kinetic friction coefficient between the test piece A and the test piece B produced in Example 1, both test pieces were washed with ion-exchanged water at 70 ° C. for 15 hours, and the contact angle was again measured. And the coefficient of kinetic friction were measured.

[Table 1]From the results in Table 1 above, hydrophilization and vulcanization were performed simultaneously.
The products are more hydrophilic and hydrophilic than those that have been hydrophilized after vulcanization.
This shows that the lubricating property hardly deteriorates with time. [Method of measuring contact angle and dynamic friction coefficient] Contact Angle (Sessi)
le Drop Method) Base material 1.0 × 1.0 × 0.1cm³  Measuring device Contact angle meter CA-S type (Kyowa Science) Measuring conditions ・ Drop volume 1-10μl air
Measure the angle ・ 25 ℃ 65% RH 2. Dynamic Coefficient of Friction (Friction Coeffici)
ent) Base material 1.0 × 3.0 × 0.1cm³  Measuring device Surface property measuring instrument HEIDON-14 (HEIDON) Measurement conditions ・ Ion-exchanged water ・ Loading 100g ・ Speed100mm / min Example 3
Unvulcanized silicone rubber in 10% aqueous solution of luamide
Immerse and heat at 95 ° C for 0 seconds, 30 seconds, and 6 seconds.
0 seconds and 180 seconds were set, and each test piece was prepared.
Similarly, the contact angle and the coefficient of kinetic friction were measured.

[Table 2] This shows that the hydrophilicity and surface lubricity can be further increased by extending the hydrophilization treatment time. Example 4 DCBPO was blended with 2% by weight of unvulcanized silicone rubber * ¹ and rolled.
Performed for 2 hours to obtain a substrate. This substrate was pre-vulcanized under the following conditions. Next, hydrophilic treatment was performed under the same conditions as in Example 1.

[Table 3] From this result, after the organic peroxide is blended into the unvulcanized rubber molded product, it is partially vulcanized by heating, and furthermore, the organic peroxide that can contribute to the heating remains, and vulcanization is possible. It can be seen that the effect of the present invention is exhibited even in some cases. Example 5 DCBPO was blended with 2% by weight of unvulcanized silicone rubber, rolled, and then cold pressed to 12%.
Performed for a time to obtain a substrate. Acrylic acid 10wt%
Heat treatment was performed in steam at 121 ° C. for 1 minute. FIG.
Shows the processing equipment. First, the valves 2A and 2B are opened, and the pressure is reduced by a vacuum pump. Next, valve 2
B was closed, the temperature of the entire reaction vessel 5 was raised from room temperature to 121 ° C. over 15 minutes in the oven 6, heated at 121 ° C. for 1 minute, stopped heating, gradually cooled, and then cooled with the silicone test piece 4.
Take out. Thereafter, the substrate was washed with ion-exchanged water for 10 minutes, and then heat-treated at 160 ° C./5 hours in air. Then, it was immersed in 0.1 N sodium hydroxide for 1 minute, washed with ion exchanged water, and further dried to prepare a test piece C. The contact angle and the coefficient of kinetic friction were measured in the same manner as in Example 3. Contact angle (deg) 47.5 Dynamic friction coefficient 0.030

[0012]

According to the present invention, hydrophilization and vulcanization can be carried out in the same step, and the obtained hydrophilic polymer not only exhibits excellent hydrophilicity and surface lubricity, but also has hydrophilicity or lubricity. Over time can be minimized.

[Brief description of the drawings]

FIG. 1 is a model diagram showing an example of an apparatus for processing a vulcanized rubber molded product used in the present invention.

[Description of Signs] 1 Acrylic acid solution tank 2A valve 2B valve 3 Vacuum pump 4 Silicone test piece 5 Reaction tank 6 Oven

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08C 19/28 C08J 7/16

Claims (1)

(57) [Claims] 1. A hydrophilic composition comprising contacting an unvulcanized rubber molded product containing an organic peroxide with a hydrophilic radically polymerizable monomer and heating the organic peroxide at a temperature not lower than the active point of the organic peroxide. Method for treating a vulcanized rubber molded product.