JPH0359982B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a method for forming a metal thin film on the surface of a synthetic resin molded product and a molded product. In particular, the present invention relates to a method for forming a metal thin film on the surface of a synthetic resin molded product, and in particular, a plasticizer bleed-out prevention crosslinked layer and a vapor-deposited metal on the surface of a soft PVC molded product containing a large amount of plasticizer. The present invention relates to a method for simultaneously applying a layer and a molded article. Prior Art Generally, when depositing synthetic resin molded products, the surface of the molded product is treated with a chromic acid mixture, corona discharge, low-temperature plasma, etc. in order to improve the adhesion between the deposited metal and the molded product. . However, in the chromic acid mixture method, there are problems in the disposal of the waste liquid, and in the corona discharge method, the adhesiveness of the dirt adhering to the surface of the molded product or the plasticizer exuding from inside the molded product is a problem. It is not possible to completely remove or prevent inhibitory substances, and in low-temperature plasma treatment, the process is divided into two stages: plasma treatment and vapor deposition.
There are many problems in terms of product costs and how to store intermediate products. Among synthetic resin molded products, those made from soft PVC are widely used in a variety of applications due to their easy moldability, low cost, and high strength. However, during molding of soft PVC molded products, plasticizers, stabilizers, fillers, lubricants, ultraviolet absorbers, antioxidants, anti-fouling agents, adhesives, pigments, etc. are added depending on the purpose. Therefore, these additives have the disadvantage that they bleed out onto the surface of the molded product due to the heat and pressure during molding or over time when left standing. Due to this drawback, it is not possible to obtain sufficient adhesion when depositing metal onto PVC film, and even if the film shows good adhesion initially, the metal may peel off over time. It was hot. Summary of the Invention The present invention was discovered as a result of intensive studies aimed at solving these problems. The present invention provides a method for forming a metal thin film by depositing metal vapor generated at high temperature under reduced pressure on the surface of a synthetic resin molded product, in which the surface of the molded product is irradiated with one or both of low-temperature plasma of an inorganic gas and ultraviolet light. The present invention provides a method for forming a metal thin film on the surface of a synthetic resin molded product, characterized in that the vapor deposition treatment is performed to crosslink the resin in the surface layer of the synthetic resin molded product at the same time as the formation of the metal thin film. By the way, there are currently many aspects of the vapor deposition reaction mechanism under low-temperature plasma and vacuum ultraviolet light irradiation that are still unknown. However, it is believed that ultraviolet light plays a particularly important role in the present invention. That is,
Similar to vacuum ultraviolet light, low-temperature plasma also generates ultraviolet light when gas atoms transition from an excited state to a transition state. This is thought to promote crosslinking in the surface layer at the same time as spatter cleaning on the surface of the molded product by the excited gas atoms. In addition, since ultraviolet rays have the property of being able to pass through metals, cross-linking will proceed further in the molded parts where a thin metal film has already been formed, forming a complete bleed-out prevention layer. (Refer to ``Synthesis and Material Processing by Plasma Reaction'', supervised by RIKEN, edited by Ionics Co., Ltd., published July 3, 1980, pp. 171-179). Therefore, the adhesiveness of the product according to the present invention is
It remains excellent both initially and over time. DETAILED DESCRIPTION OF THE INVENTION The details of this invention will be described below. The synthetic resin molded products covered by the present invention include:
Polyvinyl chloride and its copolymer molded products, polyolefin molded products such as polyethylene and polypropylene, polyester molded products, polyamide, polyimide and their copolymer molded products, polyurethane molded products, acrylics such as MMA and BMA, and their copolymers. Molded products, synthetic rubber molded products such as ABS, SBR, etc.
Although it can be applied to all fields of synthetic resins, the effect is particularly noticeable in polyvinyl chloride molded products and synthetic rubber molded products such as ABS and SBR, so it is preferable.
Moreover, as long as the molded article is the same, there are no particular restrictions regarding its form, manufacturing method, and composition. Inorganic gases to be introduced include CO, CO ₂ , O ₂ ,
Examples include N ₂ , H ₂ and inert gases such as Ar and He, but CO and a mixture of CO and Ar are particularly effective. The amount of introduced gas is based on the pressure inside the vessel.
A pressure of 10 ^-4 to 10 Torr is optimal; if the pressure is higher than this, the deposition rate of the deposited metal will be extremely reduced, resulting in a long time required to obtain a predetermined metal thickness, resulting in poor efficiency. Furthermore, if the pressure is lower than this, the spatter cleaning effect due to the excited gas atoms will be poor, and the crosslinking efficiency on the surface of the molded article will also be reduced, making it impossible to obtain a metal coating with good adhesion. The metal to be evaporated can be general metals such as metal conductors such as Al and Ti, metal oxides such as ZnO and MgO, and metal sulfides such as MoS, and the metal can be selected depending on the purpose and use. , there are no particular restrictions. The low-temperature plasma treatment may be performed by any method such as high frequency discharge, microwave discharge, corona discharge, etc., but an internal electrode method is particularly preferred. Next, the apparatus and conditions used for vapor deposition will be explained in detail with reference to FIGS. 1 and 2. The device is a high-frequency ion plating device or a normal vacuum evaporation device equipped with a high-frequency discharge electrode, a DC application electrode, and a gas introduction tube (the first
(Fig. 2) and a high-frequency ion plating apparatus in which a mercury lamp is installed in place of the high-frequency electrode (Fig. 2) may also be used. 1 is a substrate (cathode), 2 is an evaporation tank (anode), and the heating temperature of each is determined depending on the evaporation source and the heat resistance temperature of the molded product. Further, the evaporation tank may be of a crucible type or an electron beam type, and is not limited to the apparatus shown in the figure. 5 is a coil for high frequency discharge, and the optimum processing power is 50 ~
500W, particularly preferably 50 to 300W. 5' is a mercury lamp, and the optimal processing power is
100~500W, UV range is 100~250nm,
Particularly preferably processing power 200-350W, ultraviolet region
It is 100-250 nm. 6 is a shielding plate, and although the material is not particularly selected, it is preferable that the surface on the substrate side is
It is also good to use a metal coated with a metal that reflects ultraviolet rays, such as AlMgF ₂ , to increase efficiency.
9 is a DC power supply, and the applied voltage is 0.05 to 5kV
The optimum value is determined depending on the metal deposited. 1 and 2, 3 is a heater, 4 is a gas introduction tube, 7 is a sample for deposition, 10 is a gas cylinder, 11 is a high frequency power source, 11' is an optical oscillation circuit, 12 is a vacuum pump, 13 is a thermocouple. The optimal processing time is 20 to 80 minutes when vapor deposition is performed in a low-temperature plasma atmosphere.If this time is short, the crosslinked layer on the surface of the molded product is thin and has satisfactory adhesion and durability. If the length is longer than this, the etching of the metal surface by the excited gas molecules will proceed, making it impossible to obtain a smooth surface. Also, when performing evaporation under vacuum ultraviolet light irradiation, the optimum time is 10 to 60 minutes; if it is shorter than this, a sufficiently thick evaporated metal layer cannot be obtained, and if it is too long, the resin of the molded product itself may be damaged. This results in deterioration. The shape of the final product after vapor deposition is, especially in soft PVC, when viewed from the metal surface side, the vapor deposited metal layer 14,
It has a three-layer structure (FIG. 3) consisting of a soft PVC crosslinked layer 15 and a soft PVC 16, and the soft PVC crosslinked layer acts as a layer to prevent plasticizers and other adhesion inhibiting substances from seeping out. Also, depending on the application, a metal vapor deposited layer may be provided on both sides, or one side may have a metal vapor deposited layer and the other side may have a crosslinked layer formed only by low temperature plasma treatment and/or vacuum ultraviolet light irradiation. . As described above, the various vapor-deposited products obtained by the present invention have a wide range of applications and uses, such as soft
It is thought that PVC films with Al deposited on them can be applied to fields that were previously considered impossible with soft PVC films, such as heat-insulating wall materials, thermal/cold bags, and packaging films. Examples Next, examples of the present invention will be shown. Example 1 PVC (Denka SS-103) 100 as a treated sample
Parts by weight, DOP (dioctyl phthalate) 60 parts by weight, EPS (epoxidized soybean oil) 3 parts by weight, Ba-Zn
The mixture adjusted with 2 parts of system stabilizer is made into a 0.1 mm film using a heated roll, and this is used as a sample.
After installing this item in the specified position in the device shown in Figure 1 and evacuating the inside of the sparge to 10 ^-5 Torr,
CO/Ar (mixing ratio 7/3) was introduced through the gas introduction pipe to maintain the pressure inside the vessel at 0.05 Torr, and glow discharge was performed at a power consumption of 200 W.
Al was used as the vapor-deposited metal, and the applied DC voltage was 200 V.
The experiment was carried out under conditions of a substrate temperature of 80°C and a crucible temperature of 900°C. The adhesion between the metal and the film was measured using the base method. The results are shown in Table 1. (*Note) Base method: Cut a film coated with resin or metal on the surface into 1 cm squares, and make cuts at 1 mm intervals in both the vertical and horizontal directions to make a total of 100 squares.
Attach commercially available cellophane tape to the film and rub it strongly 10 times with a metal rod weighing 1 kg. after that,
Peel off the cellophane tape and check the degree of peeling of the coating. The state of peeling is expressed by the number of squares (retention rate; %) of the remaining coating material.

[Table] Example 2 The same sample used in Example 1 was set at a predetermined position in the apparatus shown in Figure 2, and after the chamber was evacuated, CO/
After introducing Ar (7/3) to an internal pressure of 0.05 Torr, the wavelength was measured using a 300W mercury lamp.
UV treatment was performed at 185 nm or 254 nm. Using Al as the vapor deposition metal, applied voltage 200V, substrate temperature
The test was carried out under conditions of 80°C and crucible temperature of 900°C. Adhesion was evaluated using the substrate method, but in order to see the influence of adhesion-inhibiting substances on leaching, we also conducted measurements on samples that had been subjected to a bleed acceleration test for comparison. The results are shown in Table 2. (*Note) Bleed acceleration test: Leave at 70℃ with gear open for one week.

[Table] Example 3 A plasticizer elution test was conducted on the Al-deposited PVC films shown in Examples 1 and 2 to examine the effects of glow discharge plasma treatment and vacuum ultraviolet treatment. The test was conducted using the following procedure. First, carefully wipe off the Al on the Al-deposited PVC film with a phosphoric acid solution so as not to damage the film surface, and place it on the bottom of the elution test container. After adding 50 ml of hexane and shaking at 40°C for 5 hours, the DOP extracted into the hexane was analyzed by gas chromatography using dinonyl phthalate as a standard. The results are shown in Table 3.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a schematic diagram of a glow discharge plasma processing apparatus useful for carrying out the method of the present invention, FIG. 2 is a schematic diagram of a vacuum ultraviolet processing apparatus useful for carrying out the method of the present invention, and FIG. 1 is a schematic cross-sectional view of a soft PVC molded product treated by the method of the present invention. 1... Substrate (cathode), 2... Crucible (anode), 3... Heater, 4... Gas introduction tube, 5... High frequency coil,
5'... Mercury lamp, 8... Metal for vapor deposition, 9... DC power supply, 14... Vapor deposited metal layer, 15... Crosslinked resin layer, 16
...Resin layer.

Claims (1)

[Scope of Claims] 1. A method for forming a thin metal film by depositing metal vapor generated at high temperature under reduced pressure onto the surface of a synthetic resin molded product, wherein one of a low-temperature plasma of an inorganic gas and ultraviolet light is applied to the surface of the molded product. Alternatively, a method for forming a metal thin film on the surface of a synthetic resin molded product, characterized in that the vapor deposition treatment is performed while irradiating both, and at the same time as the formation of the metal thin film, the resin on the surface layer of the synthetic resin molded product is crosslinked. . 2. The method according to claim 1, wherein the inorganic gas is CO. 3. The method according to claim 1, wherein the inorganic gas is a mixture of CO and Ar. 4. The method according to claim 1, wherein the wavelength range of the ultraviolet light is 100 to 250 nm. 5. The method according to claim 1, wherein the synthetic resin molded product is a soft vinyl chloride molded product. 6 The product structure after vapor deposition starts from the outermost layer to the vapor deposited metal layer/
The method according to claim 5, comprising a three-layer structure of a soft PVC crosslinked layer/soft PVC layer.