JPS6352107B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for surface modification of plastic molded articles. In general, transparent plastic molded products have inferior scratch resistance, abrasion resistance, and chemical resistance compared to inorganic glass, so they are coated with metal or inorganic oxides, such as A method of surface modification by precipitating inorganic hard substances such as silicon oxide, zirconium oxide, and aluminum oxide to form a coating has been adopted. Furthermore, for the purpose of preventing reflection in plastic molded products, there is a method of obtaining an antireflection film by alternately laminating inorganic hard substances having different refractive indexes on the surface of the molded product using the above method. However, the hard inorganic coating obtained by this method has disadvantages such as poor adhesion to plastic fabrics, poor hot water resistance and high humidity resistance, cracks, and peeling of the coating. The present inventor has conducted extensive research in order to solve the above problems. As a result, by plasma-treating a plastic molded product to form a modified layer on its surface and cleaning the modified layer with a solvent, the adhesion of the film formed by the inorganic hard material can be significantly improved. This discovery led us to propose the present invention. The present invention involves plasma-treating a plastic molded product to form a modified layer on its surface, then washing the modified layer with a solvent to remove a portion of the modified layer, and then precipitating an inorganic hard substance on the surface. This is a method for surface modification of plastic molded products, which is characterized by forming a film. In the present invention, the modified layer refers to the cutting of molecular chains by plasma treatment of a plastic molded product.
Refers to the layer portion where degeneration etc. have occurred. In the present invention, the plastic molded product is not particularly limited. For example, polyunsaturated esters such as polymethyl methacrylate, polymethacrylate, polyethylene terephthalate, polyacrylate, polymethyl acrylate; polystyrene;
Polyvinyl chloride; Epoxy resin; Polyamides,
Polycarbonate; Polyallyl carbonates such as polydiethylene glycol bisallyl carbonate; Polymers such as cellulose acetate plastic, or molded products made of copolymers of monomers forming these polymers or copolymers of the monomers and other monomers. Can be mentioned. In particular, for highly transparent plastic molded products made of polymers such as polymethacrylic esters, polyacrylic esters, polycarbonates, and polyallyl carbonates, it can be used without losing its optical properties. The method of the present invention, which allows surface modification, is particularly effective. The most important feature of the present invention is that a plastic molded product is plasma-treated to form a modified layer on its surface, and then the modified layer is washed with a solvent. In the past, plasma treatment has been used to improve the adhesion of plastic molded articles, such as plastic films. However, the adhesion of the film formed by the inorganic hard material described below is
Mere plasma treatment of plastic molded products is not fully satisfactory. In the present invention, by cleaning the modified layer formed by plasma treatment with a solvent, the adhesion between the plastic molded product and the inorganic hard material coating can be significantly improved. In the present invention, plasma treatment can be performed by a known method. For example, oxygen, a mixed gas of oxygen and an inert gas such as argon, etc. are preferably used as the atmospheric gas. In particular, a mixed gas of oxygen and an inert gas is preferable because it has a large effect on plasma treatment. In addition, the pressure is about 0.5 to 2 Torr,
Appropriate gas flow rate is about 10 to 300 ml/min.
Furthermore, the discharge power may generally be selected within the range of 50 to 500W. Furthermore, the treatment time varies somewhat depending on the magnitude of the discharge power and cannot be determined unconditionally, but generally 0.2 to 10 minutes is suitable. Furthermore, in the present invention, the modified layer formed on the surface of the plastic molded product is cleaned to such an extent that only a portion of the modified layer remains. That is, cleaning to remove all the modified layer is not preferred because the effect of plasma treatment is almost completely lost and sufficient adhesion of the film cannot be obtained. The solvent used for cleaning can be used without any particular restriction as long as it has the ability to remove at least part of the substances present in the modified layer. Generally, it is preferable to use a solvent that does not substantially dissolve the base material of the plastic molded article, since there is no risk of dissolving the entire modified layer. Examples of typical solvents include alcohol solvents such as methanol, ethanol, and isopropanol, ketone solvents such as acetone, organic solvents consisting of aromatic solvents such as benzene and toluene, etc. alone or in combination, and dodecylbenzenesulfonic acid. Examples include neutral detergent aqueous solutions such as . Further, as specific examples of combinations with plastic molded products, for example, methanol is suitable for polymethyl methacrylate, and acetone is suitable for polydiethylene glycol bisallyl carbonate. The cleaning method using a solvent is not particularly limited. For example, commonly used methods include immersion in a solvent, a combination of this method and cleaning using an ultrasonic cleaner, a method of spraying a solvent, and a method of wiping with a cloth, paper, etc. containing a solvent.
In particular, a method in which cleaning using an ultrasonic cleaner is combined is preferred because the cleaning can be completed in a single hour. In the present invention, the surface of the plastic molded article is modified by washing the modified layer with a solvent and then depositing an inorganic hard substance on the surface. Of course, when depositing an inorganic hard material, the solvent remaining on the surface should be removed by drying or other means. Any known method can be used without any particular restriction as a method for depositing a coating of an inorganic hard material on a plastic molded product. For example, vacuum evaporation method, ion plating method, sputtering method, etc. are common. In particular,
When the film is formed by vacuum evaporation, the effect of the treatment is remarkable and the film exhibits excellent adhesion to the surface of the plastic molded product, and is therefore preferably employed in the present invention. Further, the thickness of the coating is not particularly limited, but is generally 0.1 to 10μ. Further, as the inorganic hard substance, any inorganic substance that can be deposited on the plastic surface by the above method can be used without particular limitation, and it may be selected as appropriate depending on the purpose. For example, silicon oxide (SiOx, X=1-2), aluminum oxide, etc. are generally used to impart scratch resistance. In addition, in order to provide antireflection properties, aluminum oxide, silicon oxide, magnesium fluoride, etc. are used as low refractive index materials, and titanium oxide, zirconium oxide, etc. are used as high refractive index materials. and a high refractive index material may be alternately laminated so as to have an optical thickness. Additionally, metals such as aluminum can also be used. As can be understood from the above explanation, according to the method of the present invention, it is possible to form a film that has extremely excellent adhesion to plastic molded products. Although the mechanism by which such an effect is expressed is not yet clear, it is assumed that the surface of the plastic molded product that has been subjected to plasma treatment and solvent cleaning has some influence on the precipitation of inorganic hard materials on the surface. There is. Examples are shown below to specifically explain the present invention, but the present invention is not limited to these Examples. Example 1 A polydiethylene glycol bisallyl carbonate plate produced by cast polymerization was used as a plastic molded product. First, the molded product was washed with acetone and thoroughly air-dried to a clear state, and then subjected to plasma treatment under the conditions shown in Table 1. Next, it was washed in an ultrasonic cleaner using acetone as a solvent for 5 minutes, air-dried again, and then vacuum evaporated under conditions of 10 ^-6 Torr to obtain a silicon oxide film with a thickness of 3 μm. The following various adhesion tests were conducted on the silicon oxide film formed by this method. (1) Goban test: After making 100 squares of 1 mm x 1 mm on the surface of the sample using a cutter knife with a sharp tip, commercially available cellophane tape was attached and quickly peeled off, and the number of squares remaining was displayed. (2) Hot water resistance test: The film was immersed in boiling water for 2 hours, pulled out, and the appearance of the film was visually observed. A film with peeling, cracking, or blistering was rated as ×, and a film with good appearance without change was rated as ○. (3) High humidity resistance test: 3 at 60℃ and 100% humidity
The film was left to stand for a day, and the appearance of the film was visually observed. A film with peeling, cracking, or blistering was rated as ×, and a film with good appearance without change was rated as ○. The results are also shown in Table 1. In addition, in the above method, a case in which plasma treatment was not performed and a case in which cleaning with a solvent after plasma treatment was not performed are also shown as comparative examples.

[Table] Note that Nos. 1, 2, 4, and 6 are comparative examples.
Example 2 2,2-bis-[4-
A plate of a copolymer (2-methacryloxy)-ethoxy-3,5-dibromophenyl]-propane and styrene with a weight ratio of 2/3 was prepared in the same manner as in Example 1. A silicon oxide film was formed. An adhesion test was conducted on this silicon oxide film in the same manner as in Example 1. The results are shown in Table 2. In addition, a comparative example in which cleaning with a solvent was not performed after plasma treatment is also shown.

[Table] Note that 1, 2, 4, and 6 are comparative examples.
Example 3 A commercially available polymethyl methacrylate plate and a commercially available polycarbonate were used as plastic moldings. First, each molded plate was washed with methanol and thoroughly air-dried to a clear state, and then O ₂ /
Total pressure 0.7 Torr with mixed gas of Ar (10/30 ml/min),
Plasma treatment was performed for 1 minute at a discharge power of 50W.
Next, using methanol as a solvent, it was washed in an ultrasonic cleaner for 5 minutes, air-dried again, and then vacuum evaporated in the same manner as in Example 1 to obtain a silicon oxide film with a thickness of 3 μm. The silicon oxide film formed by this method was subjected to an adhesion test in the same manner as in Example 1, and the results are shown in Table 3.
In addition, in the above method, a case in which plasma treatment was not performed and a case in which cleaning with a solvent was not performed after plasma treatment are also shown as comparative examples.

[Table] Note that 1, 2, 4, and 5 are comparative examples.
Example 4 A polyethylene glycol bisallyl carbonate plate produced by the same cast polymerization as in Examples 1 and 2, and 2,2-bis-[4-(2-methacryloxy)-ethoxy-3,5-dibromophenyl] ]−
Plates (TB) made by copolymerization of propane and styrene
-St copolymer) was first washed with acetone and thoroughly air-dried to a clear state, then plasma treated under the same conditions as in Example 3, and then treated with acetone in an ultrasonic cleaner for 5 minutes. It was washed and air-dried again. Then, vacuum evaporation was performed in the same manner as in Example 1 to obtain an aluminum oxide film with a thickness of 3 μm.
An adhesion test was conducted on the aluminum oxide film formed by this method in the same manner as in Example 1. The results are shown in Table 4. In addition, in the above method, a case in which plasma treatment was not performed and a case in which cleaning with a solvent was not performed after plasma treatment are also shown as comparative examples.

[Table] Note that 1, 2, 4, and 5 are comparative examples.
Example 5 An experiment similar to Example 4 No. 3 was conducted except that the inorganic hard material was replaced with aluminum. An adhesion test was conducted on the obtained film in the same manner as in Example 1. As a result, Goban eye test 100,
The results were 0 in the hot water resistance test and 0 in the high humidity resistance test.

Claims (1)

[Claims] 1 A plastic molded product is plasma-treated to form a modified layer on its surface, and then the modified layer is washed with a solvent to remove a part of the modified layer, and then an inorganic hard material is applied to the surface. A method for modifying the surface of a plastic molded product, characterized by forming a film through precipitation. 2. The method according to claim 1, wherein the inorganic hard material is deposited by vacuum deposition.