JPH09296057A - Method for forming irregular surface on polymer molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a desired surface structure on a molding by irradiating the surface of a molding of a mixture containing a plasmadecomposable organic polymer and a non-plasma-decomposable organic polymer with a plasma to decompose and remove part of the plasmadecomposable organic polymer on the surface. SOLUTION: A benzene solution containing about 3wt.% plasmadecomposable organic polymer material (e.g. polymethyl methacrylate) is mixed with a benzene solution containing about 3wt.% non-plasma-decomposable organic polymer material (e.g. polystyrene) in a weight ratio of 5/95-95/5. Next, the combined solution is cast, and the wet film is dried at room temperature to form a film having a specified thickness. The surface of this film is irradiated with an oxygen plasma having a gas pressure of about 0.02-0.1Torr and a power of about 2-200W for about 1-60min to remove part of the plasmadecomposable organic polymer ad to thereby obtain a film having an irregular structure on the order of 100Å to several μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for forming an uneven surface of a polymer molded article. More specifically, the present invention provides a porous or protruding surface, that is, an uneven surface, on a surface of a polymer molded body having various shapes such as a film, a fiber, a block, and a granule composed of a plurality of specific polymer materials. The present invention relates to a method for efficiently forming a surface.

[0002]

2. Description of the Related Art An organic polymer material is easy to mold, and can have various mechanical properties such as elasticity and strength and various properties from hydrophilic to hydrophobic depending on the kind. It is widely used in many fields as molded articles such as films, fibers, structures, and granules.

It is known that the function of a molded article made of such an organic polymer material is greatly influenced by its surface structure. If necessary, various surface treatments, for example, a stretching treatment under a heated and melted state are required. It is processed according to each purpose by oxidative etching using plasma or ultraviolet light, mechanical etching, or the like.

[0004] Among the molded bodies that have been surface-treated in this way, polymer molded bodies having, for example, porous or protruding surfaces are useful as functional structural materials, separation membranes, medical materials, functional fibers, and the like. It is. However, any of the conventional methods for forming a surface structure of a polymer molded article has a disadvantage that it is difficult to form an arbitrary surface structure, and it is difficult to construct the surface structure in advance in a functional design.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a method for forming a porous, protruding or the like on the surface of a polymer molded product such as a film, a fiber, a block, or a powder. An object of the present invention is to provide a simple method for forming a desired uneven structure arbitrarily and efficiently.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, as a molding material, a plasma decomposable organic polymer material and a plasma non-decomposable organic polymer material have been used. It has been found that the object can be achieved by irradiating the surface of the molded body composed of the mixture with plasma to decompose and remove at least a part of the plasma-decomposable polymer material present on the surface. The invention has been completed.

That is, according to the present invention, the surface of a molded article made of a mixture of a plasma-decomposable organic polymer material and a plasma non-decomposable organic polymer material is irradiated with plasma, and the plasma-decomposable organic polymer present on the surface is irradiated. Disclosed is a method for forming a concavo-convex surface of a polymer molding, which comprises decomposing and removing at least a part of a material.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, it is necessary to use a mixture of a plasma-decomposable organic polymer material and a plasma non-decomposable organic polymer material as a molding material. Here, the plasma-decomposable and non-decomposable plasma does not need to be completely decomposed by plasma irradiation or not decomposed at all, and in two or more organic polymer materials forming a molded body, It suffices that there is a relation that one is relatively more easily decomposed by plasma than the other.

Examples of the plasma-decomposable organic polymer material include poly (methyl methacrylate), poly (ethyl methacrylate), poly (isopropyl methacrylate),
Poly (butyl methacrylate), polyvinyl alcohol,
Examples thereof include polyvinyl acetate, cellulose and derivatives thereof, and copolymers containing these as main components. These may be used alone or in combination of two or more.

On the other hand, as the plasma non-decomposable organic polymer material, for example, polyacrylonitrile, polystyrene,
Examples thereof include polydimethylsiloxane, polysulfone, polyphenylene ether, styrene / butadiene rubber, isoprene rubber, and fluorine rubber. These may be used alone or in combination of two or more.

By mixing such different types of polymer materials, a three-dimensional structure compatible with the bulk is formed according to the combination and the mixing ratio. It is known that synergistic physical properties of materials can be obtained. On the other hand, on the surface of the molded body made of this mixed material, depending on the combination and mixing ratio of the polymer materials,
A sea-island structure or a striped structure is formed. According to the method of the present invention, at least a part of one component (plasma-decomposable polymer material) of the polymer material constituting such a structure on the surface of the molded body is selectively removed by irradiation treatment with plasma, and the unevenness is obtained. Surface structure can be formed.

In the method of the present invention, the mixing ratio of the plasma-decomposable polymer material and the non-plasma-decomposable polymer material is not particularly limited, and may be appropriately selected according to the desired physical properties and desired surface structure of the molded article. The weight ratio is generally selected in the range of 5:95 to 95: 5.

[0013] The shape of the polymer molded article used in the method of the present invention is not particularly limited.
Any shape, such as fibers, blocks, and granules, can be used.

The plasma source used in the method of the present invention may be a non-polymerizable plasma source.
There is no particular limitation. For example, non-reactive plasma using argon, helium, or the like may be used, or oxidation-reactive plasma using oxygen, air, or the like may be used. It is preferable to appropriately select according to the etching characteristics.

In general, the plasma irradiation can etch the surface of the molded product to a thickness of about 100 μm to several μm without deteriorating the inherent properties of the polymer material. On the other hand, the size of the phase-separated structure on the surface of the molded body made of the mixed polymer material according to the present invention is generally several hundreds of μm to several μm in diameter, so that it is selectively etched away by plasma irradiation to form the uneven surface structure. It is suitable for forming

This plasma irradiation can be carried out by a conventionally known method. The generation of plasma is generally performed by an excitation method using radio waves under vacuum conditions, but there is no particular limitation on the generation method, and audio waves having a longer wavelength, kilohertz-order audio waves, megahertz-order radio waves, It is possible to use shorter wavelength microwaves. The pressure of the gas used as the plasma is generally selected in the range of 0.01 to 1.0 torr, preferably in the range of 0.02 to 0.1 torr. Further, the appropriate discharge output depends on the type and pressure of the gas, the plasma generator, and the like, but is not particularly limited as long as the discharge can be generated. Generally, discharge occurs in the range of 2 to 200 W,
Etching is efficient. A processing time of about 1 to 60 minutes is sufficient.

[0017] By such plasma irradiation, the plasma-decomposable polymer material on the surface of the polymer molded body is selectively decomposed and removed, thereby forming an uneven surface structure. For example, when the molded body has a sea-island structure or a striped structure, the plasma-decomposable polymer material is preferentially removed to form a porous or protruding structure.

[0018]

According to the present invention, a porous or protruding surface structure can be arbitrarily adjusted by a simple method of irradiating the surface of a polymer molded product such as a film, fiber, block, or granular material with plasma. It can be formed efficiently. The polymer molded article having such a surface structure is useful, for example, as a functional structural material, a separation membrane, a medical material, a functional fiber, and the like.

[0019]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A benzene solution containing 3% by weight of poly (methyl methacrylate) (hereinafter abbreviated as PMMA) and a benzene solution containing 3% by weight of polystyrene having a molecular weight of 250,000 were mixed at a weight ratio of 1: 9. The resulting solution was cast and air-dried at room temperature to form a film having a thickness of about 45 μm. From the scanning electron micrograph of the surface of this film, it was confirmed that the PMMA component formed an island structure having a diameter of 0.6 to 0.7 μm. Next, when the surface of this film was irradiated with oxygen plasma of 0.1 Torr and 50 W for 30 minutes, a surface having a porous structure with an average diameter of 1 μm was formed.

Example 2 In the same manner as in Example 1, a film having a thickness of about 45 μm and made of a mixture of PMMA and polystyrene in a weight ratio of 2: 8 was prepared. From the scanning electron micrograph of the surface of this film, it was confirmed that the PMMA component formed an island structure having a diameter of 2 μm. Next, on the surface of this film,
When oxygen plasma was irradiated under the same conditions as in Example 1, a surface having a porous structure with a diameter of about 2.5 μm was formed.

Example 3 In the same manner as in Example 1, a film having a thickness of about 45 μm made of a mixture of PMMA and polystyrene in a weight ratio of 8: 2 was prepared. From the scanning electron micrograph of the surface of this film, it was confirmed that the PMMA component formed a sea structure and the polystyrene formed an island structure. Next, when the surface of this film was irradiated with oxygen plasma under the same conditions as in Example 1, a surface having a protrusion structure composed of polystyrene portions having a diameter of 5 to 10 μm was formed.

Claims (3)

[Claims] 1. At least one of the plasma-decomposable organic polymer materials existing on the surface of a molded body made of a mixture of a plasma-decomposable organic polymer material and a plasma non-decomposable organic polymer material, which is irradiated with plasma. A method for forming a concavo-convex surface on a polymer molded body, which comprises decomposing and removing a portion. 2. The method according to claim 1, wherein the mixing ratio of the plasma-decomposable organic polymer material and the plasma non-decomposable organic polymer material is 5:95 to 95: 5 by weight. 3. The method according to claim 1, wherein the molded body is a film, a fiber, a block or a granule.