JPH06304867A - Forming method for water repellent surface - Google Patents

Abstract

PURPOSE:To form a hydrophobic resin surface into high water repellency by blasting water soluble solid fine grains to the hydrophobic resin surface, forming this surface changed into a rough surface, and next by washing the solid fine grains, left in this roughed surface, removed. CONSTITUTION:By blasting water soluble solid fine grains to a hydrophobic resin surface of 0.5% or less water absorption, the surface is changed into a rough surface. Since a grindstone used in this blast processing is a water soluble fine grains, abrasive grains, left in a roughed processed surface, are easily removed only by wash. In the hydrophobic resin surface thus processed, since cone-shaped fine irregular protrusions are formed, high water repellency is displayed. In hydrophobic resin used as a processed removal surface, for instance, silicone resin, fluororsin, polyethylene, polypropylene, etc., are listed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming a water repellent surface.

[0002]

2. Description of the Related Art For various purposes such as prevention of pollution by rainwater and the like, improvement of propulsion performance of ships, prevention of adhesion of marine organisms,
There is a demand for development of water-repellent surface and improvement of performance for various devices. The water-repellent material means a material having a contact angle θ between solid and liquid (water) of 90 ° or more, and a material having a contact angle θ of less than 90 ° is considered hydrophilic. As typical water repellent materials, silicone resins with a contact angle of about 90 ° to 110 ° and polytetrafluoroethylene having a contact angle of about 110 ° are known, but as long as they are used alone, they are completely water repellent (θ Water repellency close to = 180 °) can hardly be expected. According to a recent study, when analyzing the water repellent performance of polytetrafluoroethylene alone, conical protrusions with a height of 3 to 30 μm are arranged on the surface at intervals of 1 to 10 μm (ratio of height to interval is about 3). It is considered that they are closely arranged, and it has been found that the presence of such surface irregularities greatly contributes to the water repellent performance.

A sand blast method is well known as a method for forming fine uneven projections on the surface without the purpose of imparting water repellency. This sandblasting method is a method in which abrasive grains such as silica sand are sprayed onto the surface to be processed at high speed to roughen the surface. Therefore, it is considered that this method is applied to the surface of the hydrophobic resin such as polytetrafluoroethylene to roughen the surface. However, when this method is simply applied to the formation of a water-repellent surface, since the abrasive grains remain on the surface of the object to be treated after blasting, removal of the abrasive grains requires a considerable amount of work and can be carried out on an industrial scale. Has many problems.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a water-repellent surface which facilitates removal of abrasive grains and facilitates industrial implementation in forming the water-repellent surface by the blast method. To do.

[0005]

Means for Solving the Problems The present invention to achieve the above object is to roughen a surface of a hydrophobic resin having a water absorption rate of 0.5% or less by blasting water-soluble solid fine particles on the surface,
Next, the solid fine particles remaining on the roughened surface are washed and removed with water. Since the abrasive grains used in the blast treatment of the present invention are water-soluble fine particles, the abrasive grains remaining on the roughened surface to be treated can be easily removed by washing with water.

Further, since the conical fine projections and depressions are formed on the surface of the hydrophobic resin treated according to the present invention, it exhibits higher water repellency which is further improved as compared with the surface of the hydrophobic resin alone. Will be things. The hydrophobic resin used as the surface to be treated in the present invention is not particularly limited as long as it is a synthetic resin having a water absorption rate of 0.5% or less. For example, silicone resin, fluororesin, polyethylene, polypropylene,
Examples thereof include acrylic resin, epoxy resin, polyimide resin, polyphenylene sulfide resin, and polyether sulfone resin. Among these, fluororesins, silicone resins, polyethylene and polypropylene are particularly preferable. Of the fluororesins, polytetrafluoroethylene is particularly preferable. Polyethylene and polypropylene are preferable because the efficiency of plastic deformation due to the abrasive grains is high.

The water-soluble solid fine particles used as the blast abrasive grains in the present invention are not particularly limited as long as they are water-soluble substances. Preferred examples include sodium chloride,
Examples thereof include potassium chloride and calcium chloride, but sodium chloride (sodium chloride) particles are most preferable because of easy availability. It is desirable that the grain size of the abrasive grains be as small as possible and have high hardness. Average particle size 20-200 μ
m is better. Further, it is preferable that the abrasive grains have a sharp edge.

The blasting conditions used in the present invention are selected depending on the hardness of the hydrophobic resin to be treated and the type of abrasive grains, but the injection pressure is ^{2 to} 50 kgf / cm ^2, preferably 5.0 to 10.0 kgf / cm 2.
^It is good to do in the range of ² . The jetting direction is not particularly limited, but the jetting is preferably performed at an angle of 30 to 150 ° on the surface to be treated, and more preferably within a range of ± 45 ° in the direction perpendicular to the surface to be treated. The distance between the blast gun and the surface to be treated should be 10 to 30 mm. From the viewpoint of work efficiency, if the injection pressure is set high and the projection time is short, a water-repellent surface can be efficiently obtained.

[0009]

【Example】

Example 1 A 250 mm × 250 mm × 1 mm polytetrafluoroethylene plate (hereinafter abbreviated as PTFE, trade name Polyflon, manufactured by Daikin Industries, Ltd., water absorption rate less than 0.1%) was used as abrasive grains, and salt particles (average particle size 0.5 mm, Japanese tobacco) Blasting gun manufactured by Sangyo Co., Ltd.
The injection pressure and the injection angle were changed as shown in Table 1 by (Sandblaster manufactured by Nippon Lining Industry Co., Ltd.), and the blast treatment was performed under the condition of the injection distance of 20 mm.

Next, when the resin plate thus treated was washed with water, the salt particles of the abrasive grains could be easily removed. Then, the contact angle of the obtained surface was measured, and the results shown in Table 1 were obtained. For comparison, the contact angle of the untreated resin plate is also shown.

[0011]

[Table 1] As shown in Table 1, the contact angle of the resin plate treated by the method of the present invention is obviously higher than that of untreated resin plate.

[0012]

According to the method of the present invention, when the surface of the hydrophobic resin is blast-treated, water-soluble fine particles are used as abrasive grains. Therefore, the particles remaining on the surface to be treated after the treatment can be easily removed by washing with water. can do. In addition, the hydrophobic resin surface can be formed with high water repellency.

Claims (1)

[Claims] 1. A surface of a hydrophobic resin having a water absorption rate of 0.5% or less is roughened by blasting water-soluble solid fine particles, and then the solid fine particles remaining on the roughened surface are removed by washing with water. Method of forming water repellent surface.