JPH0559102A - Production of hydrophilic vulcanized rubber - Google Patents

Abstract

PURPOSE:To obtain a hydrophilic vulcanized rubber having excellent surface hydrophilic property and lubricity by contacting an unvulcanized rubber containing an organic peroxide with a radically polymerizable hydrophilic monomer and heating at a specific temperature. CONSTITUTION:The objective rubber having hydrophilicity or lubricity stable with time can be produced by contacting (A) an unvulcanized rubber such as silicone rubber or natural rubber compounded with an organic peroxide such as 2,4-dichlorobenzoyl peroxide with (B) a radically polymerizable hydrophilic monomer such as acrylamide and vinylpyrrolidone and heating at a temperature higher than the activation point of the above organic peroxide.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a method for making a polymer material hydrophilic, the following methods have been used. A method in which a hydrophilic resin is graft-copolymerized with 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 polymer material that has been molded and processed in the presence of a polymerization modifier 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, the organic peroxide treatment has a problem that the hydrophilicity and lubricity of the surface deteriorate with time.

[0003]

[Object] The present invention provides a method for producing a hydrophilic vulcanized rubber which solves the problems of the above-mentioned conventional techniques, simplifies the production process, and is less likely to deteriorate the hydrophilicity and surface lubricity of the rubber over time. is there.

[0004]

[Structure] A method for producing a hydrophilic vulcanized rubber according to the present invention comprises contacting an unvulcanized rubber containing an organic peroxide with a hydrophilic radical-polymerizable monomer, and heating at a temperature equal to or higher than an active point of the organic peroxide. Consists of heating at. Specifically, a method of bringing the vapor of a hydrophilic radical-polymerizable monomer into contact with an unvulcanized rubber compounded with an organic peroxide and heating at a temperature equal to or higher than the active point of the organic peroxide, or a hydrophilic radical. It is carried out by a method of immersing an unvulcanized rubber compounded with an organic peroxide in a solution of a polymerizable monomer and heating it at a temperature equal to or higher than the active point of the organic peroxide.

The reaction materials and reaction conditions used in the present invention will be specifically described below. The unvulcanized rubber compounded with the organic peroxide used in the present invention is 1. 1. An unvulcanized rubber blended with an organic peroxide, or 2. After unvulcanized rubber was mixed with organic peroxide, it was partially vulcanized, but there is still organic peroxide that can contribute to vulcanization in unvulcanized rubber, and vulcanization is possible. Refers to something.

In the present invention, since the unvulcanized rubber containing the above-mentioned at least partially unvulcanized organic peroxide is simultaneously vulcanized and hydrophilized, the grafting of the hydrophilic polymerizable monomer is carried out. Since the reaction can sufficiently react on the rubber surface and in the vicinity of the rubber surface, not only the advantage that the hydrophilization and the vulcanization can be performed in one step, but the hydrophilic vulcanized rubber obtained by the present invention is It has an excellent effect that the surface can be made hydrophilic without changing the excellent characteristics of the material, and the deterioration of the hydrophilicity with time is small.
Examples of the 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. However, the present invention is not limited to these. These unvulcanized rubbers can be used in a solid or latex state of any shape. For example, it may be in the form of chips, fibers, films, or the like.

The organic peroxide to be blended with the unvulcanized rubber can be used without particular limitation as long as it is one generally used as a vulcanizing agent. Examples thereof include 2,4-dichlorobenzoyl peroxide (DCBPO), benzoyl peroxide (BPO), di-t-butyl peroxide, dicumyl peroxide, and t-butyl perbenzoate. Further, the blending amount of these organic peroxides is determined in consideration of the intended degree of vulcanization, but it is usually preferable to blend in about 0.1 to 2.0% by weight. More preferably, it is particularly preferable to add about 1.5 to 2.0% by weight.

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

When unvulcanized rubber containing an organic peroxide is contacted with vapor of a hydrophilic radical-polymerizable monomer and heated at a temperature higher than the active point of the organic peroxide, for example, hydrophilic The method of vaporizing the solution of the radical-polymerizable monomer of (1) and contacting the unvulcanized rubber in which the organic peroxide is blended in the vapor, or the vapor of the hydrophilic radical-polymerizable monomer of an appropriate inert gas (for example, nitrogen). ), And supplied and diluted with an organic peroxide to bring into contact with an unvulcanized rubber. Further, as another method, a method of immersing an unvulcanized rubber compounded with an organic peroxide in a solution of a hydrophilic radical-polymerizable monomer, and heating at a temperature equal to or higher than the active point of the organic peroxide is used. is there. In the production method of the present invention, when the hydrophilic radical-polymerizable monomer is diluted with a solvent and used, the solvent is water-soluble, and the active sites of the organic peroxide compounded in the unvulcanized rubber are It is not particularly limited as long as it has the above boiling point and does not excessively swell the unvulcanized rubber. Water is preferably used, but organic solvents miscible with water can also be used. As the organic solvent, a solvent that dissolves rubber cannot be used, but a solvent that swells can be used. Examples of such an organic solvent include ethyl alcohol. Further, the concentration of the hydrophilic radically polymerizable monomer is preferably about 5 to 20% by weight for the reason of the effect of imparting hydrophilicity.

The heating temperature is not particularly limited as long as it is a temperature above the active point of the organic peroxide used.
Further, the treatment time is appropriately determined in consideration of the types of the unvulcanized rubber and the radical-polymerizable monomer used, or the degree of hydrophilization and vulcanization.

[0011]

【Example】

Example 1 (1) Preparation of test piece according to the present invention 2% by weight of DCBPO was blended with unvulcanized silicone rubber * ¹ , roll-rolled, and then cold-pressed for 12 hours.
It was carried out for a period of time to obtain a base material. This base material is made of acrylamide 10
wt% aqueous solution (using ion-exchanged water, 100 ° C / 10
(Prepared by boiling for more than 5 minutes to remove dissolved oxygen), heat at 95 ° C / 3 minutes, wash with ion-exchanged water for 10 minutes, and then heat in air at 160 ° C / 5 hours Processed. Then, the test piece A was washed with ion-exchanged water and further dried. Note) * ¹ Silica is mixed with vinyl silicone rubber. (2) Preparation of test piece of comparative example 2% by weight of DCBPO was blended with a condensable room temperature curable rubber * ² , and after curing at room temperature for 24 hours, the test piece of the example was prepared in the same manner as A test piece B of a comparative example was prepared by treating with a 10 wt% aqueous solution of acrylamide, and then washing, heating, washing and drying in the same manner as in the production of the test piece of the example.
And Note) * ² Consists of condensation type silicone rubber and condensation catalyst. Example 2 After measuring the contact angle and the dynamic friction coefficient of 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 measured again. And the coefficient of dynamic friction was measured.

[Table 1] From the results in Table 1 above, it is shown that what was performed at the same time as hydrophilization and vulcanization showed less deterioration in hydrophilicity and lubricity with time as compared with the one that was hydrophilized after vulcanization. [Method of measuring contact angle and dynamic friction coefficient] Contact Angle, Sessile Drop Method Base material ── 1.0 × 1.0 × 0.1cm ³ Measuring device ── Contact angle meter CA-S type (Kyowa Scientific Co., Ltd.) Measuring conditions-Drop amount 1- 10 μl air Drop a water drop on the test piece and measure the contact angle between the water drop and the water on the surface of the test piece. 25 ° C. 65% RH 2. Friction Coefficient Base material ─── 1.0 × 3.0 × 0.1cm ³ Measuring device ───Surface measuring instrument HEIDON-14 (H
EIDON) Measurement conditions-Ion-exchanged water-Weighted 100 g-Speed100 mm / min Example 3 In the method for producing the test piece of (1) of Example 1, unvulcanized silicone rubber was immersed in a 10% aqueous solution of acrylamide, Treatment time of heating at 95 ° C is 0 seconds, 30 seconds, 6
Five kinds of 0 seconds, 180 seconds and 300 seconds were set, each test piece was prepared, and the contact angle and the coefficient of dynamic friction were measured in the same manner.

[Table 2] It is shown that the hydrophilicity and the lubricity of the surface can be further enhanced by extending the hydrophilic treatment time. Example 4 2% by weight of DCBPO was blended with unvulcanized silicone rubber * ¹ , rolled, and cold pressed 1
It was carried out for 2 hours to obtain a base material. This base material was prevulcanized 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 was blended with the unvulcanized rubber, it was partially vulcanized by heating, and further, the organic peroxide that can contribute to heating remains and is vulcanizable. It is understood that the effect of the present invention can be exerted also in. Example 5 2% by weight of DCBPO was blended with unvulcanized silicone rubber, rolled, and then cold pressed to 12
It was carried out for a period of time to obtain a base material. This base material is acrylic acid 10 wt%
Heat treatment was performed at 121 ° C. for 1 minute in steam. Figure 1
Shows the equipment of the processing. First, the valves 2A and 2B are opened, and the pressure is reduced by the vacuum pump. Next valve 2
B was closed, and the temperature of the entire reaction tank 5 was raised from room temperature to 121 ° C. over 15 minutes in the oven 6, and after heating at 121 ° C. for 1 minute, the heating was stopped and gradually cooled.
Take out. Then, it was washed with ion-exchanged water for 10 minutes, and then heat-treated in air at 160 ° C. for 5 hours. Then, it was immersed in 0.1N 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 dynamic friction were measured in the same manner as in Example 3. Contact angle (deg) 47.5 Dynamic friction coefficient 0.030

[0012]

[Effect] 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. Can be prevented to a minimum.

[Brief description of drawings]

FIG. 1 is a model diagram showing an example of a vulcanized rubber manufacturing apparatus used in the present invention.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. An unvulcanized rubber compounded with an organic peroxide and a hydrophilic radically polymerizable monomer are brought into contact with each other and heated at a temperature equal to or higher than the active point of the organic peroxide. Method for producing vulcanized rubber.