JPS6136584B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing plastic molded articles having a thin metal film. More specifically, the present invention relates to a method for producing a plastic molded article having a metallic thin film on its surface area and having a metallic luster. The best way to give a plastic molded product a metallic appearance is to form a metal film on the surface of the molded product. Conventionally, methods such as vacuum deposition, hot stamping, and plating have been known as methods for forming such metal films. However, these metal film forming methods have various problems in product performance, process, etc., and are not satisfactory. For example, the vacuum evaporation method has the disadvantage that only metals with relatively low melting points such as aluminum, tin, and antimony can be used, and that it is difficult to use metals with high melting points such as chromium, and furthermore, it cannot be mass-produced. Furthermore, the low melting point metals have low hardness, discolor and corrode when scratched, and have the disadvantage of being easily eluted, and are therefore unsuitable for exterior use. Furthermore, the hot stamping method has the disadvantage that the shape of the plastic molded product is restricted in terms of processing. Furthermore, although a strong metal film can be obtained by electrolytic plating of, for example, chromium, the plating method has many disadvantages from an economical point of view, as the process is complicated and waste liquid treatment is required. In recent years, as a method to solve the above-mentioned problems, a method of obtaining a metal film of chromium or the like by a low-temperature sputtering method has been developed. However, even with this method, cracks tend to occur during the process of forming the metal film or during use, resulting in a significant loss of decorative value and peeling from the paint film, making it unpractical. be. Therefore, the object of the present invention is to obtain a bright chromium or stainless steel film (equal to or better than a plating finish) by a low-temperature sputtering method, and to solve the problem of cracking or peeling from the paint film. The object of the present invention is to provide a new method for manufacturing plastic molded products. By the way, the object of the present invention could only be achieved by specifying the undercoat, the conditions for forming the metal film, and the topcoat, and by creating a synergistic effect by combining them. That is, the present invention provides the following steps: (a) After applying an ultraviolet curable acrylic resin undercoat to the surface of the material of the plastic molded product,
A step of irradiating ultraviolet rays to form a base coat layer with a hardness of HB or more (according to a measurement method based on JIS D0202), (b) applying a degree of vacuum to the surface of the base coat layer from 6×10 ^-5 to 1
×10 ^-3 Torr, argon pressure 1 × 10 ^-4 ~ 5 ×
10 ^-3 Torr, voltage 200~600V, current density 0.2~5
A step of forming a chromium or stainless steel metal film layer with a thickness of 300 to 2000 Å by sputtering under conditions of A/dm ² , then (c) on the surface of the chromium or stainless steel metal film layer,
The main component has an OH value of 10 to 200 and an acid value of X<5.
It consists of the steps of applying a top coat consisting of an acrylic polyol with X≦12 and a non-yellowing polyisocyanate and curing it to form a top coat layer. The present invention will be explained in more detail below. In the present invention, if the material of the plastic molded article has a large coefficient of thermal expansion, the metal film may crack during formation or use. Therefore, it is desirable that the coefficient of thermal expansion be small, and practically, it is preferably 20×10 ^-5 cm/cm/°C or less. Specifically, particularly preferred materials include acrylonitrile-butadiene styrene copolymer (hereinafter referred to as
(hereinafter referred to as ABS), acrylonitrile styrene copolymer (hereinafter referred to as AS), and those coated or laminated with these copolymers. Next, the ultraviolet curable acrylic resin undercoat used in the present invention is one whose main components are a polymerizable resin component, a polymerizable solvent and/or a non-polymerizable solvent component, and a photosensitizer component. To explain more specifically, the polymerizable resin component is polymethyl methacrylate; 2 in 1 molecule.
Relatively low molecular weight compounds (oligomers) having one or more polymerizable vinyl groups, such as patented in 1972.
Oligomers represented by the following structural formula () () () () () etc. described in Patent Application Publication No. 26300 or 1979 Patent Application Publication No. 35073; [In the formula, A: -O- or -NH-, at least one A
-NH- R: C ₁ to ₁₀ divalent hydrocarbon group R′: C ₂ to ₁₀ divalent saturated hydrocarbon group R″: H or CH ₃ R〓: C ₄ to ₁₀ divalent saturated hydrocarbon group Saturated hydrocarbon group X: H or R ⁰ -CO R ⁰ : H or a C ₁ to ₁₈ hydrocarbon group or -NHR n: an integer of 0 to 14, respectively.] Polyester modified acrylic resin, e.g. 1972
Addition reaction of epichlorohydrin to α/β-ethylenically unsaturated dicarboxylic acid such as fumaric acid described in Patent Application Publication No. 27523, etc., and esterification reaction with polyhydric carboxylic acid anhydride such as phthalic anhydride, Further, a polyester-modified acrylic resin containing an unsaturated group that has been subjected to an addition reaction with an epoxy group-containing vinyl monomer such as glycidyl methacrylate; an epoxy-modified acrylic resin, such as the hydroxyl group-containing vinyl described in Patent Application Publication No. 82742 of 1972, etc. Oligomer made by reacting a polyepoxy compound with a compound obtained by reacting a monomer with a saturated polyhydric carboxylic acid anhydride, Patent Application Publication No. 1962
Examples include those made by reacting an epoxy resin prepolymer with acrylic acid, etc., as described in Publication No. 19038, etc.; or mixtures thereof; and polymerizable resin components conventionally generally used in UV-curable acrylic resin base coatings. In addition, as the polymerizable solvent component, compounds containing acryloyl group and methacryloyl group [hereinafter referred to as (meth)acryloyl group for convenience], such as methyl (meth)acrylate, ethyl (meth)acrylate, 2-(meth)acrylate Ethylhexyl, benzyl (meth)acrylate, (meth)acrylic acid 2
-Hydroxyethyl, ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate; aromatic monovinyl compounds such as styrene, vinyltoluene, α-methylstyrene; representative examples include acrylonitrile, vinyl acetate, acrylamide, diacetone acrylamide, etc. It can be used as something. Further, as typical non-polymerizable solvent components, xylene, toluene, methyl ethyl ketone, acetone, methyl alcohol, ethyl alcohol, etc. can be used. Next, as photosensitizer components, benzoin, benzoin methyl ether, benzoin isopropyl ether, anthraquinone, naphthoquinone, chloranthraquinone, tetramethylthiuram disulfide, diphenyl disulfide, benzoyl peroxide, azobisisobutyl Lonitr, 2.
2'-Azobispropane etc. can be used as a typical example. The ultraviolet curable acrylic resin undercoat used in the present invention may contain other additives such as a polymerization inhibitor and a smoothing agent, if necessary.
The appropriate blending ratio of the polymerizable component, solvent component (polymerizable solvent and/or non-polymerizable solvent), and photosensitizer component is 100:(10-200):(1-20) by weight. UV-curable acrylic resin undercoat paints are degreased.
It is applied to the surface of the treated plastic molded product using a conventional brush coating, spray coating, dip coating, curtain flow coating, roll coating, etc., and then irradiated with ultraviolet rays using a low to high pressure mercury lamp, an arc lamp, a xenon lamp, etc., and cured. The dry film thickness of the ultraviolet curable acrylic resin undercoat paint is usually approximately 10 to 50 μm. The base coat layer thus obtained needs to have a hardness of HB or more (by a measuring method based on JIS D0202), particularly preferably F or more, in order to prevent cracks from occurring in the metal film. In the method of the present invention, the UV-curable acrylic resin undercoating paint is particularly used for cold energy drying, which does not cause deterioration or damage to the plastic molded product, smooths the surface of the plastic molded product, and makes it possible to smooth the surface of the plastic molded product and the metal film. This is to provide adhesion with the material. Next, a thin metal film of chromium or stainless steel is formed on the surface of the base coat layer by sputtering. A method for forming a metal film is, for example, using a DC bipolar magnetron sputtering device, using chromium or stainless steel as a cathode target, and using a 6×
Fill a bell jar evacuated to 10 ^-5 to 1 × 10 ^-3 Torr with argon gas, and set the argon pressure to 1 ×
After setting the voltage to 10 ^-4 to 5×10 ^-3 Torr, the voltage between the two DC poles is
Discharge at 200-600V and cathode current density of 0.2-5A/ ^dm2 . The argon ions generated by the discharge impact the chromium or stainless steel of the cathode target, releasing metal atoms of chromium or stainless steel. These metal atoms travel straight through the bell gear, reach the surface of the base coat layer, and condense to form a thin metal film on the surface of the base coat layer. The voltage between the two electrodes is set to 200 as sputtering conditions.
By setting the voltage to ~600V, a favorable sputtering phenomenon occurs. If the voltage is less than 200V, the sputtering phenomenon will not occur even if it is discharged, but if the voltage is more than 600V, various industrial problems will appear. In addition, the appropriate current density is 0.2 to 5 A/ ^dm2 , and if the current density is below this range, sputtering will not occur.
On the other hand, if the temperature exceeds this range, the plastic molded product may be deformed due to temperature rise, or cracks may easily occur in the metal film, which is not preferable. Furthermore, a metal film that is less susceptible to cracking can be obtained at a vacuum degree of 6×10 ^-5 to 1×10 ^-3 Torr and an argon pressure of 1×10 ^-4 to 5×10 ^-3 Torr. If the degree of vacuum and argon pressure are outside this range,
Sputtering does not occur, or even if a metal film is formed, cracks are likely to occur. FIG. 1 shows the relationship between the degree of vacuum and the argon pressure. In the figure, part A is the range in which an excellent metal film with less cracks can be obtained. The thickness of the metal film in the present invention is usually 300 to 2000.
Å is appropriate. If it is less than that, a shiny metal film cannot be obtained. Note that the stainless steel used in the present invention is
SUS305, SUS309, SUS310, SUS316,
Austenitic materials such as SUS317, SUS321, and SUS347 are suitable. Next, on the surface of the metal film layer, the main component is an OH value of 10 to 200 and an acid value of 5<X≦12.
A top coat consisting of acrylic polyol and non-yellowing polyisocyanate is applied and cured to form a top coat layer. The top coating used in the present invention consists of an acrylic polyol and a non-yellowing polyisocyanate as main components. The acrylic polyol preferably has an OH value of 10 to 200, particularly preferably 40 to 100. Within this range, a coating film with good adhesion to the metal film and excellent weather resistance etc. can be obtained. If the CH number is less than 10, the solvent resistance of the paint film will be poor, while if the OH number is more than 200, the paint film will be prone to cracking, and it will be necessary to use a large amount of polyisocyanate, making it less economical. There are also problems and I don't like it. Furthermore, when the acid value of the acrylic polyol is greater than 12, pinholes and cracks are likely to occur in the coating film, and the weather resistance is also poor, which is not preferable. The equivalent ratio of OH groups in acrylic polyol to NCO groups in polyisocyanate (OH/NCO) is
0.6 to 1.2 is appropriate. Crosslinking progresses within this range,
A coating film with excellent weather resistance, moisture resistance, water resistance, abrasion resistance, etc. can be obtained. As the acrylic polyol component, α/β- such as methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.
〓〓〓〓〓
Esters of unsaturated carboxylic acids; monobasic acids having >C=C< bonds such as (meth)acrylic acid and crotonic acid; polybasic acids having >C=C< bonds such as itaconic acid and fumaric acid; 2- Compounds having >C=C< bonds such as hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and ethylene glycol mono(meth)acrylate, and further having -OH; >C such as glycidyl (meth)acrylate =C< has a bond, and

Compound with [formula]; (meth)acryla Mido et al.

[Undercoat paint formulation]

Epoxy modified acrylic resin (1) 50 parts Polyester modified acrylic resin (2) 50 parts Methyl methacrylate 40 parts Xylene 60 parts 2-ethoxyacetophenone 2 parts Silicone leveling agent 1 part (1) Diabeam K-6105A: Mitsubishi Rayon Co., Ltd.
(2) Diamond Beam K-4116: Made by Mitsubishi Rayon Co., Ltd. After setting for 10 minutes at room temperature, it was irradiated with ultraviolet rays for 60 seconds using a 5KW high-pressure mercury lamp, and the pencil hardness was F.
A base coat layer with a thickness of 15 μm was obtained. Then, using a DC dipole magnetron sputtering device, a sputtering layer of 500 Å was formed under the following sputtering conditions.
A chromium metal film was obtained. [Sputtering conditions] Degree of vacuum: 8 x 10 ^-5 Torr Argon pressure: 5 x 10 ^-4 Torr Voltage: 500 V Current density: 2 A/dm ² Discharge time: 80 seconds Next, a top coat of the following composition was spray-painted on the metal film. [Top coating composition] Acrylic polyol (OH value 50, acid value 8.0, glass transition temperature 80°C) resin solution with viscosity S-W (non-volatile content 50wt%) 100 parts Dismodule N-75(3) 15 parts Xylol 50 parts Butyl acetate 30 parts Cellosolve acetate 20 parts (3) Biuret compound of hexamethylene diisocyanate: manufactured by Bayer AG After setting at room temperature for 10 minutes, it was force-dried at 60° C. for 30 minutes to obtain a top coat layer with a thickness of 20 μm. The resulting plastic molded product is the same as electrolytic plating.
There was more brilliance than anything else. After the forced drying, it was left at room temperature for 7 days and various performance tests were conducted. The results were as shown in Table 1. Example 2 After obtaining a base coat layer on the surface of the ABS resin molded product in the same manner as in Example 1, a 450 Å stainless steel (SUS310S) [composition C: 0.08 , Si: 1.50, Mn: 2.00, P: 0.04,
S: 0.03, Ni: 20.00, Cr: 25.00, Fe: 51.35]
A metal film was obtained. [Sputtering conditions] Degree of vacuum: 1 x 10 ^-4 Torr Argon pressure: 5 x 10 ^-4 Torr Voltage: 200 V Current density: 2 A/dm ² Discharge time: 80 seconds Next, a top coat of the following composition was spray-painted on the metal film. [Top coating composition] Acrylic polyol (OH value 100, acid value 6.0, average molecular weight 15,000, glass transition temperature 70°C) resin solution with viscosity SW (non-volatile content 50wt%) 100 parts Dismodule N-75 25 60 parts xylol 30 parts butyl acetate 30 parts cellosolve acetate After setting at room temperature for 10 minutes, it was force-dried at 60°C for 30 minutes to obtain a top coat layer with a thickness of 18 μm. The resulting plastic molded product had a brightness equal to or higher than that of electrolytic plating. After the forced drying, it was left at room temperature for 7 days and various performance tests were conducted. The results were as shown in Table 1. Example 3 After obtaining a base coat layer and a chromium metal film on the surface of an ABS resin molded product in the same manner as in Example 1, a top coat of the following composition was spray-painted on the metal film. [Top coating composition] Acrylic polyol (OH value 50, acid value 10.0, glass transition temperature 80°C) resin solution with viscosity S-W (non-volatile content 50 wt%) 100 parts Dismodule N-75 15 parts Xylol 50 parts Butyl acetate 30 20 parts of cellosolve acetate After setting at room temperature for 10 minutes, it was force-dried at 60°C for 30 minutes to obtain a top coat layer with a thickness of 17 μm.
The resulting plastic molded product had a brightness equal to or higher than that of electrolytic plating. After the forced drying, it was left at room temperature for 7 days and various performance tests were conducted. The results were as shown in Table 1. Comparative example 1 Undercoat paint was exposed to 45% ultraviolet rays using a 5KW high-pressure mercury lamp.
A plastic molded article was obtained in the same manner as in Example 1, except that irradiation was carried out for seconds to obtain a base coat layer having a pencil hardness of B and a film thickness of 16 μm. The results of various performance tests are shown in Table 1. As is clear from Table 1, cracks occurred in the heat resistance test in Comparative Example 1 whose base coat layer had a pencil hardness of B, whereas cracks occurred even after 24 hours in Example 1 whose base coat layer had a pencil hardness of F. No generation of was observed, and it was found that the heat resistance was excellent. Comparative example 2 The paint with the following composition was used as the top coat, and the film thickness was 18μ.
A plastic molded article was obtained in the same manner as in Example 1 except that a top coat layer was obtained. [Top coating composition] Viscosity S of acrylic polyol (OH value 50, acid value 13.1, average molecular weight 20,000, glass transition temperature 66℃)
-W resin solution (non-volatile content 70wt%) 100 parts Dismodule N-75 15 parts Xylene 50 parts Butyl acetate 30 parts Cellosolve acetate 20 parts The results of various performance tests of the obtained plastic molded products are shown in Table 1. . As is clear from Table 1, Comparative Example 2 using an acrylic polyol with an acid value greater than 12 had poor weather resistance, whereas Examples using an acrylic polyol with an acid value of 12 or less did not become cloudy and had good weather resistance. turned out to be excellent. 〓〓〓〓〓

[Table] (4) A molded product having an acrylic lacquer base coat layer, an aluminum metal film layer formed by vacuum evaporation, and an acrylic lacquer top coat layer on the surface of the ABS resin molded product. (i) Based on JIS D0202. (ii) irradiate with a sunshine weatherometer;
The surface condition was investigated. (iii) The surface condition was examined by placing it in an atmosphere with a temperature of 40°C and a humidity of 95%. (iv) The surface condition was examined by immersing it in tap water at a temperature of 40°C. (v) It was placed in a constant temperature bath at a temperature of 80°C, and the surface condition was examined. (vi) Based on JIS Z2371−1955. (vii) The surface condition was examined using a reciprocating abrasion tester (load: 1 kg, contact surface: cotton canvas). Additional relationship Original invention (original patent number 1113704 patent application filed in 1978)
No. 70604; Patent Publication No. 6452 of 1982), 1(a) After applying an ultraviolet curable acrylic resin undercoat to the surface of a plastic molded product, it is irradiated with ultraviolet rays to achieve a hardness of HB or higher (based on JIS D0202). (b) step of forming a base coat layer (depending on the measurement method); (b) applying a vacuum level of 6×10 ^-5 to 1×10 ^-3 Torr thereon;
Argon pressure 1×10 ^-4 to 5×10 ^-3 Torr, voltage
A step of forming a metal film layer of chromium or stainless steel with a thickness of 300 to 2000 Å by sputtering under conditions of 200 to 600 V and a current density of 0.2 to 5 A/dm ² , and then (c) forming a metal film layer of 300 to 2000 Å thick on top of it with an OH value of 10 as the main component. A method for producing a plastic molded article having a metal thin film, comprising the steps of applying and curing a top coat consisting of an acrylic polyol with an acid value of 5 or less and a non-yellowing polyisocyanate. 2. A plastic molded article having a metal thin film according to claim 1, wherein the top coating has an OH/NCO (equivalence ratio) value of acrylic polyol and non-yellowing polyisocyanate of 0.6 to 1.2. Production method. 3 The plastic molded product has a coefficient of thermal expansion of 20×
10 ^-5 cm/cm/°C or less, the method for manufacturing a plastic molded article having a metal thin film according to claim 1. 4 The material of the plastic molded product is acrylonito.
The present invention relates to a method for producing a plastic molded article having a metal thin film according to claim 1, characterized in that the plastic molded article has a metal thin film made of a allyl-butadiene-styrene copolymer or an acrylonitrile-styrene copolymer. By the way, in the present invention, (1)(a) After applying an ultraviolet curable acrylic resin undercoat to the surface of the material of the plastic molded product, irradiation with ultraviolet rays is performed to obtain a hardness of HB or higher (JIS
(b) Step of forming a base coat layer (by measurement method based on D0202), (b) a vacuum degree of 6 × 10 ^-5 to 1 × 10 ^-3 Torr thereon,
Argon pressure 1×10 ^-4 to 5×10 ^-3 Torr, voltage
A step of forming a metal film layer of chromium or stainless steel with a thickness of 300 to 2000 Å by sputtering under conditions of 200 to 600 V and a current density of 0.2 to 5 A/ ^dm2 , and then (c) forming a metal film layer of chromium or stainless steel with a thickness of 300 to 2000 Å on top of it by sputtering under conditions of 200 to 600 V and a current density of 0.2 to 5 A/dm2; is 10~
200, a method for producing a plastic molded article having a metal thin film, comprising the steps of applying and curing a top coat consisting of an acrylic polyol with an acid value X of 5<X≦12 and a non-yellowing polyisocyanate. (2) The top coat has OH/NCO (equivalent ratio) of acrylic polyol and non-yellowing polyisocyanate.
A method for producing a plastic molded article having a metal thin film according to claim 1, characterized in that the metal thin film has a value of 0.6 to 1.2. (3) The coefficient of thermal expansion of the plastic molded product is 20×
10 ^-5 cm/cm/°C or less, the method for manufacturing a plastic molded article having a metal thin film according to claim 1. (4) Production of a plastic molded article having a metal thin film according to claim 1, wherein the material of the plastic molded article is an acrylonitrile-butadiene-styrene copolymer or an acrylonitrile-styrene copolymer. It concerns the method. Therefore, the present invention is an invention that uses all or the main parts of the essential parts of the original invention as the main parts of the essential parts of the original invention, and achieves the same purpose. It is.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the degree of vacuum and the argon pressure in order to obtain a metal film that does not cause cracks. In the figure, range A is a preferred range. 〓〓〓〓〓

Claims (1)

[Claims] 1 (a) After applying an ultraviolet curable acrylic resin undercoat to the surface of the material of the plastic molded product, irradiation with ultraviolet rays results in hardness of HB or higher (JIS
(b) Step of forming a base coat layer (according to the measurement method based on D0202) on the base coat layer at a vacuum level of 6×10 ^-5 to 1×10 ^-3 Torr and an argon pressure of 1×10 ^-4 to 5×10 ^-3 Torr. , voltage 200~
A step of forming a metal film layer of chromium or stainless steel with a thickness of 300 to 2000 Å by sputtering under conditions of 600 V and a current density of 0.2 to 5 A/ ^dm2 ,
Then (c) on top of that, the main component has an OH value of 10 to 200,
A method for manufacturing a plastic molded article having a metal thin film, comprising the steps of applying and curing a top coat consisting of an acrylic polyol with an acid value X of 5<X≦12 and a non-yellowing polyisocyanate. 2 The top coat has an OH/NCO (equivalent ratio) value of acrylic polyol and non-yellowing polyisocyanate.
2. A method for producing a plastic molded article having a metal thin film according to claim 1, wherein the plastic molded product has a metal thin film of 0.6 to 1.2. 3 The coefficient of thermal expansion of the plastic molded product is 20×
10 ^-5 cm/cm/°C or less, the method for manufacturing a plastic molded article having a metal thin film according to claim 1. 4 The material of the plastic molded product is acrylonito.
2. The method for producing a plastic molded article having a metal thin film according to claim 1, wherein the material is a lyl-butadiene-styrene copolymer or an acrylonitrile-styrene copolymer.