JPH03153859A - Surface-modified plastic - Google Patents

Abstract

PURPOSE:To produce plastic having superior scratch resistance and high water repellency by forming a metal oxide layer on a plastic substrate and laminating a metal oxide-fluororesin mixed layer on the metal oxide layer. CONSTITUTION:A layer contg. one or more kinds of metal oxides such as SiO2, Al2O3 and ZrO2 is formed by vacuum deposition or other method on a plastic substrate of polycarbonate, polyethylene terephthalate, etc. A metal oxide- fluororesin mixed layer is then laminated by sputtering on the metal oxide layer. The fluororesin may be polytetrafluoroethylene. A coating film having superior scratch resistance, high water repellency and superior adhesion is formed on the surface of the plastic.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to plastics with excellent scratch resistance and high water repellency.

(Conventional technology) As a technology for modifying the surface of plastic.

By forming a fluororesin coating on a rubber molded product using a high-frequency sputtering method, and then forming a mixture coating of metal or inorganic material and fluororesin.

A technique for improving durability and reducing surface frictional resistance is known (Japanese Unexamined Patent Publication No. 60-67655).

Further, after forming a sputtered film of polytetrafluoroethylene or a sputtered film of molybdenum sulfide on the substrate using an ion beam sputtering method.

A technique for obtaining a solid lubricant film with excellent durability by laminating sputtered films of polytetrafluoroethylene is known (Japanese Patent Application Laid-open No. 41291/1983).

(Problems to be Solved by the Invention) When modifying the surface of plastic using the above-mentioned high-frequency sputtering method, there are problems with the adhesion between the first layer of fluororesin and the substrate, and the scratch resistance of the first surface. There is also a problem.

Furthermore, when the surface of plastic is modified using the ion beam sputtering method, there are also problems with the adhesion and scratch resistance of the film.

The present invention has been made in order to solve the above-mentioned conventional problems, and its purpose is to provide a surface formed with a coating having excellent scratch resistance, high water repellency, and excellent adhesion. Our goal is to provide modified plastics.

(Means for Solving the Problems) The surface-modified plastic of the present invention has a metal oxide layer formed on a plastic substrate, and a mixed layer of metal oxide and fluororesin laminated on the metal oxide layer. It is characterized by the fact that the above object is achieved.

Note that the metal oxide layer is made of, for example, Sin.

5iOz, AhO+, 1r02. Mg[],
Examples include a layer containing one or more metal oxides such as Zn[] and TiO2.

In addition, the types of plastic base materials used for the substrate include, for example, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, vinyl chloride resin,
polystyrene, polyimide.

Examples include polypropylene, diethylene glycol carbonate, polyethylene, ABS resin, polyether sulfane, and polyether ether ketone.

Moreover, the form may be a molded article or a film.

In addition, various methods such as sputtering, ion blasting, physical vapor deposition such as vacuum evaporation, or plasma CVD may be used to form the metal oxide layer.

In addition, it is more preferable that a fluororesin layer is further layered on the mixed layer on the metal oxide layer.

(Example) An embodiment of the present invention will be described below.

FIG. 1 shows a vacuum evaporation apparatus used to form the first layer of the coating used to create the surface-modified plastic of the present invention. In the figure, 13 indicates a vacuum chamber, and the vacuum chamber 13 is adjusted to an appropriate degree of vacuum (specifically, I
X 10-' Torr or less), and after exhausting, oxygen gas is introduced by opening and closing valves 11 and 12.

Two water-cooled copper hearths 14 are installed at the bottom of the vacuum chamber 13,
15 is arranged, and one hearth 14 has S1
The other hearth 15 is filled with evaporation source A for 0x film formation.
is filled with an evaporation source B for forming a SiOx film. The hearth 14.15 has an electron gun 14a.

15a (JST-10c manufactured by JEOL Ltd.) are attached to each of the electron guns 14a and 15a, and the electrons generated by the electron guns 14a and 15a are as follows.

The electron beam is accelerated under a high voltage and focused into a fine beam to form a high energy density electron beam, which is irradiated onto the surfaces of the evaporation sources A and B in the hearths 14 and 15.

At the upper part of the vacuum chamber 13, a mounting jig 19 for mounting a polycarbonate substrate (hereinafter simply referred to as the substrate) C of 50 x 50 x 2 mm is arranged at a position facing the hearth 14.15. The mounting jig 19 allows the substrate C to be placed at a distance of 40 cm from the surfaces of the evaporation sources A and B.
It will be located at a distance of m. In addition.

A shutter 18 is interposed between the mounting jig 19 and the hearth 14.15.

The evaporation sources A and B of the hearths 14 and 15 are evaporated by irradiation with the electron beam, and based on the evaporation.

A thin film is formed on the surface of the substrate C supported by the mounting jig 19. The degree of thin film formation can be determined using a crystal oscillation type film thickness monitor 1 placed near the mounting jig 19.
It is monitored by 0.

Figure 2 shows the preparation of the surface-modified plastic of the present invention.

In particular, a sputtering device used for forming the second and subsequent layers of the coating is shown. In the figure, 23 indicates a sputtering chamber;

The exhaust system 21, which is a combination of a rotary pump and an oil diffusion pump, is used to suitably
orr or less), and after exhausting, argon gas as sputtering gas is introduced by opening and closing a valve 22.

At the upper part of the sputtering chamber 23, there is an anode 2 that supports the substrate C on which the film has been formed by vacuum evaporation in a suspended state.
4 is placed.

In the lower part of the sputtering chamber 23, a target 2 serving as a cathode is connected to a matching circuit 27 while being shielded by a shield member 26 at a position facing the anode 24.
8 is placed. Note that a shutter 25 is interposed between the target 28 and the anode 24.

After the inside of the sputtering chamber 23 is evacuated and a sputtering gas is introduced into the chamber, a high frequency wave is applied to the target 28 to generate a discharge between the two poles.

The atoms ejected from the surface of the target 28 are as follows.

While reacting with active ions in the atmosphere in the room into which the sputtering gas has been introduced, the sputtering gas adheres to the substrate C on the opposing anode 24 side, and a thin film is formed on the surface thereof.

FIG. 3 (side view) and FIG. 4 (plan view) show specific examples of the target 28. The target 28
In this example, fan-shaped pieces 28b made of fluororesin (specifically, polytetrafluoroethylene with a thickness of 2IIffl) are arranged radially on a disk 28a made of quartz glass (Sin-), and the coverage is set to 0.1. It was established as follows.

Specific results of producing the surface-modified plastic of the present invention using the vacuum evaporation device and the sputtering device will be described in detail below.

<Example 1> First, the inside of the vacuum chamber 13 was evacuated to 1 x 10-' Torr or less using the vacuum evaporation apparatus shown in FIG. 1, and then the electron beam was The SiO in the hearth I was heated to form a film on the surface of the substrate C to a thickness of approximately 500 mm under the conditions shown in Table 1. Thereafter, the introduction of oxygen gas was stopped, and the SlO□ in the hearth 2 was heated without breaking the vacuum, and a film was formed to a thickness of 3 μm under the conditions shown in Table 1. The silicon oxide-coated substrate C thus obtained was taken out of the vacuum evaporation apparatus and attached in a suspended state to the anode 24 in the sputtering chamber 23 of the sputtering apparatus shown in FIG. A target 28 shown in FIG. 4 was arranged opposite to the anode 24. After this,
After evacuating the inside of the sputtering chamber 23 to 2 x 10-'Torr or less, Ar gas is introduced into the sputtering chamber 23 as a sputtering gas using a mass flow meter, and the gas is evacuated so that the internal pressure becomes 3 x 10-3Torr. The flow rate is adjusted and high frequency is applied to the target 28 as a cathode.

Sputtering was performed at an output of 50 W for about 10 minutes.

A 500 nm thick film was formed on a further surface of the silicon oxide coated substrate C. The properties of the surface of the obtained coating were evaluated by the following tests.

■Steel wool test: Rotate the sample 20 times while pressing 5 ooo of steel wool against the sample surface with a certain pressure. The surface condition of the film thereafter was visually observed, and the maximum pressure at which the film surface was not scratched was taken as an index of scratch resistance.

■Wettability test Evaluation was made by the contact angle with respect to water.

■Membrane adhesion test Evaluation was made according to JIS K5400.

<Example 2> The substrate used and the vapor deposition of Sin and SiO□ were the same as in Example 1.
I did it in the same way. The same procedure as in Example 1 was carried out except that the coverage of the 5in2 target with the second layer of polytetrafluoroethylene was set to 0.3.

<Example 3> A third layer was formed on the sample obtained in the same manner as in Example 2 using the sputtering apparatus shown in FIG.
Using a target made of polytetrafluoroethylene and Ar as a sputtering gas at a pressure of 3 x 1O-3
Sputtering was performed at Torr with an RF output of 50 W for 1 minute.

<Examples 4 to 8> These examples used the metal oxides shown in Table 1.
Each layer was formed under the conditions shown in . Table 1 shows the film formation conditions and the scratch resistance 1 and surface wettability results of the samples.

Comparative Example 1 Table 1 shows the results of scratch resistance 1 and surface wettability of a polycarbonate substrate without coating treatment.

Comparative Example 2> Substrate and Si port used: Vapor deposition of 5I02 was carried out in the same manner as in Example 1, and the formation of the second and subsequent layers was not performed. Other film forming conditions and characteristics of the obtained samples are shown in Table 1.

Comparative Example 3 A polytetrafluoroethylene film was directly formed on a polycarbonate substrate by sputtering.

Other film forming conditions and characteristics of the obtained samples are shown in Table 1.

Comparative Example 4 On the silicon oxide layer formed under the same conditions as in Example 1, a film was formed to a thickness of approximately 500 mm in the same manner as in Example 3 using polytetrafluoroethylene as a target. Ta. Other film forming conditions and characteristics of the obtained samples are shown in Table 1.

(Left below) As is clear from these results, in the surface-modified plastic of the present invention, the adhesion between the core layer and the plastic substrate is improved by providing the metal oxide layer as the first layer.
This is an improvement over the conventional case in which a mixture layer is provided between layers. Moreover, the adhesion between the core layer and the mixture layer becomes excellent.

Furthermore, by increasing the thickness of the first metal oxide layer, the scratch resistance of the surface-coated plastic is improved.

Note that the film thickness may be determined as appropriate depending on the application.

In addition, the second layer, which is a mixture of a metal oxide layer and a fluororesin, exhibits water repellency on one surface, and by changing the target composition during sputtering, water repellency can be achieved over a wide range. It is possible to control. That is, when the metal oxide component of the target is increased, the scratch resistance of the film improves, but the water repellency decreases, so the target composition may be determined as appropriate depending on the purpose.

If even better water repellency is required, a third layer may be formed using a target made only of fluororesin (Example 3). Since the third layer is formed on the mixture layer, the adhesion of the third layer is dramatically improved compared to when the third layer is formed directly on the metal oxide.

In addition, the film formation rate by the vacuum evaporation is 300 to 400
Although the film forming rate is approximately 1 person/min, a high film forming rate is preferable as long as the substrate is not damaged by heat. The thickness of the deposited film may be appropriately determined depending on the purpose; the thicker the film, the better the scratch resistance. When the substrate is made of polycarbonate resin, extremely excellent scratch resistance can be achieved if the thickness is 2 μm or more. Further, the coverage of the target used in the sputtering apparatus can be varied, for example, from <0.1 to 0.7 as shown in Table 1.
The coverage ratio may be appropriately determined depending on the purpose; surface lubricity and water repellency increase in proportion to this area ratio. Also,
Due to the water repellency of the substrate coated on one surface as described above, antifouling hardening can be obtained, as well as an antistatic effect due to 8102 on the surface.

(Effects of the Invention) As detailed above, the surface-modified plastic of the present invention includes a metal oxide layer formed on a plastic substrate and a mixture of metal oxide and fluororesin laminated thereon. Due to the presence of the surface coating layer, a film having excellent scratch resistance and water repellency as well as excellent adhesion is formed on the plastic surface. Therefore 1
The present invention provides a surface-modified plastic that can solve the conventional problems. In addition, a fluororesin layer is further laminated on the surface coating layer.

The above-mentioned water repellency is further improved, and a surface-modified plastic with good layer strength can be obtained.

[Brief explanation of the drawing]

Figure 1 shows the surface-modified plastic of the present invention.
FIG. 2 is a schematic diagram showing a vacuum evaporation device used in forming a layer, and FIG. FIG. 3 is a side view showing a target used in the sputtering apparatus, and FIG. 4 is a plan view thereof. 13--Vacuum chamber, 14.15--Water-cooled copper hearth,
14a, 15a...Electronic iron, 23...Sputtering chamber, 24...Anode, 28...Tagera), A,
B... Evaporation source, C... Substrate. that's all

Claims (2)

[Claims] 1. A surface-modified plastic characterized in that a metal oxide layer is formed on a plastic substrate, and a mixed layer of metal oxide and fluororesin is laminated on the metal oxide layer. 2. The surface-modified plastic according to claim 1, wherein a fluororesin layer is laminated on the mixed layer.