JPH0823063B2 - Manufacturing method of plastic articles coated with inorganic thin film. - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plastic article having an inorganic thin film, and particularly to a plastic article having an inorganic thin film having both excellent scratch resistance and heat resistance.

<Prior Art> A treatment for providing various functions by providing an inorganic thin film on the surface of a plastic article is widely performed, and, for example, a treatment for a plastic spectacle lens, a CRT panel and the like has recently been rapidly spread. These generally have an antireflection multilayer film, but it is expected that many new ones such as a plastic window material having a heat ray reflective film will expand the market in the future.

These inorganic thin films include metal oxides and nitrides,
Alternatively, a single-layer or multi-layer film made of metal itself is used. Generally, two main problems that occur when such an inorganic thin film is provided on the surface of a plastic article are that it is easily scratched and that cracks are likely to occur due to temperature rise.

Regarding the susceptibility to scratches, since the thickness of the inorganic thin film generally does not exceed 1 micron, the scratch resistance is poor because the underlying plastic substrate is soft even if the thin film itself has a large strength. It is known to bring about the result. In order to provide a hard film on a soft substrate to improve scratch resistance, it is not effective unless the thickness of the hard film is 2 μm or more. Therefore, it has been attempted to improve the scratch resistance by providing a hard coating having a thickness of 2 μm or more between the plastic substrate and the inorganic thin film, and recently it has been found that the scratch resistance is almost satisfactory. Became.

<Problems to be Solved by the Invention> However, although scratch resistance can be improved by using a method of providing such a hard coat between an inorganic thin film and a plastic substrate, the inorganic thin film Since the film has a high density, cracks may occur in the inorganic thin film due to the difference in the thermal expansion coefficient between the plastic substrate and the inorganic thin film when the temperature rises inevitably during use of the product or vacuum deposition of the inorganic thin film. There was a serious problem that it became easier.

<Means for Solving the Problems> In order to solve the above-mentioned conventional problems, the present invention forms the inorganic thin film at a low vapor deposition rate while irradiating an ion beam. Preferably, a thin film of a polymeric substance is further provided on the surface of the inorganic thin film.

That is, the present invention is directed to coating a metal oxide thin film by vacuum vapor deposition on a surface of a plastic substrate coated and cured with a polysiloxane-based coating composition while irradiating with an ion beam, and a film forming rate The initial period of 2-50% of the total optical thickness of the oxide thin film should be kept at 10 angstroms per second at the maximum, and then the film formation rate should be kept above 10 angstroms per second. And a method for producing a plastic article coated with a metal oxide thin film.

In the present invention, a plastic substrate, preferably a hard-coated plastic substrate described below, is coated with an inorganic thin film on its surface by vacuum deposition. At this time, it is preferable that the vapor deposition rate be slowed in the initial stage, that is, until at least the first 2% portion of the total thickness (optical thickness), more preferably 10% portion, is formed.

Specifically, it is preferably 10 angstroms per second or less. This film formation rate can be controlled by changing the heating temperature of the vapor deposition source and the like.

If the initial deposition rate exceeds 10 angstroms per second, the inorganic thin film may crack due to the difference in the coefficient of thermal expansion between the inorganic thin film and the substrate due to the temperature increase during use of the product or during film deposition. It tends to occur. The reason is probably that the inorganic substance adhering to the substrate at a high film formation rate is made uniform by the migration effect, and both are in close contact with each other on the entire boundary surface between the substrate and the inorganic thin film.
It is considered that the stress due to the difference in thermal expansion concentrates on the boundary surface, resulting in cracks. When the film formation rate is reduced at least in the initial stage of vapor deposition as in the present invention, the migration effect is unlikely to occur and microscopic non-uniformity of the film or film porosity occurs, and the stress due to the thermal expansion difference is It is considered that the concentration of stress is relaxed because it is dispersed inside the thin film, and as a result, the occurrence of cracks in the inorganic thin film is prevented.

The film forming rate after the initial stage of vapor deposition may be kept the same as the initial one, but is usually kept at a large value, for example, about 20 angstroms per second in order to improve the production rate. As an example, the film deposition rate is maintained at 10 angstroms per second at most during the period in which the film thickness is 2 to 50% of the total optical thickness of the inorganic thin film, and then the film deposition rate exceeds 10 angstroms per second. , Maintain at 20 angstroms per second, for example.

In the present invention, the thin film is irradiated with an ion beam at the same time when the inorganic thin film is formed by the above-mentioned vacuum deposition. The irradiated ion beam ionizes the molecules of the vapor-deposited inorganic substance evaporated from the source of the vacuum vapor deposition, thereby increasing the packing density of the vapor-deposited substance adhering to the substrate, and as a result, the adhesion strength between the inorganic substance thin film and the base material increases. To do.

The types of ions used for ion beam irradiation are nitrogen,
Commonly used gases such as oxygen and argon can be used, but the most effective is argon. The power of ion beam irradiation should be high unless the substrate and the hard coat on it are affected. Irradiation is usually performed with an energy density of 1 to 1000 μA, preferably 10 to 500 μA per 1 cm ^{2 of the} surface area of the plastic article to be coated with the antireflection film.

When the energy density is lower than 1 μA / cm ² , the effect of increasing the filling degree of vapor deposition particles in the inorganic thin film by ion beam irradiation is insufficient. Conversely, the energy density is 1000μ
When it is higher than A / cm ² , the inorganic thin film is easily corroded by the etching effect, which is not preferable.

Generally, before the inorganic thin film coating process by vacuum deposition,
The water adsorbed on the surface of the plastic substrate to be coated needs to be removed by heating, but in the present invention, this water removal can also be performed by the preliminary irradiation with the ion beam.

That is, for example, the plastic substrate to be coated is raised in a vacuum chamber equipped with an ion beam source and a vacuum deposition source, and only ion beam illumination is performed at the above energy density for 5 seconds before simultaneously starting ion beam illumination and vacuum deposition. ~ 20 minutes, more preferably 20 seconds to 10 minutes.

There are two types of ion guns, which are the source of generation of ion beams, which are already on the market at present, and they are called Kaufman type and cold-cassod type. The Kauffman type is for ionizing gas atoms by the impact of thermoelectrons, and the cold cathode type is for ionizing by using a high-voltage electric field. In the present invention, either of these types may be used. .

The inorganic thin film in the present invention is an optical thin film such as an antireflection film or a heat ray reflective film. For example, in the case of an antireflection film, a three-layer antireflection film is usually used. This, if the center wavelength of the wavelength range to be prevented and reflection lambda _O, medium refractive index layer from the substrate side in the configuration of thickness is _{λ O / 4-λ O /} 2-λ O / 4 - high refractive index A layer and a low refractive index layer are sequentially laminated. SiO ₂ is usually used for the low refractive index layer. For the high refractive index layer, TiO ₂ , ZrO ₂ , Ta ₂ O ₅ or the like, or a mixture thereof, or a material obtained by adding ytnium or praseodymium to these is used. In addition, Al ₂ O ₃ and Si ₂ O are contained in the medium refractive index layer.
₃ , Yb ₂ O ₃ etc. are used, but in the case of this medium refractive index layer,
Since it is necessary to match the refractive index to a certain limited range, since there is no suitable substance, the low refractive index-high refractive index-low refractive index layers are formed in order of λ _O using the equivalent film method. /
Recently, it has been frequently used to use a three-layer film in which each layer has a thickness of 12. Further, in the case of the heat ray reflective film, a three-layer film having a metal film sandwiched by a high refractive index dielectric film is often used.

The inorganic thin film produced by the present invention may have a so-called porous structure, but it has an atomic size, and the transparency of the thin film is not impaired at all.

Generally, when an inorganic thin film becomes porous by vacuum deposition with a low film formation rate, it usually becomes brittle,
Although scratch resistance may decrease, in the present invention,
When the inorganic thin film is formed by vacuum vapor deposition while irradiating with ions, deterioration of scratch resistance can be prevented.

Examples of the material of the plastic substrate that can be used in the present invention include resins used as transparent members such as polymethyl methacrylate (PMMA), diethylene glycol bisallyl carbonate (CR-39), polycarbonate, polystyrene, and polyester.

Before coating the surface of the plastic substrate with the inorganic thin film, a hard coat is preferably provided in advance to enhance scratch resistance of the surface. As the hard coat for plastics in the present invention, any of those roughly classified into silicone type and acrylic type can be used. In general, many silicone hard coats have a structure in which fine silica particles are dispersed in a polyorganosiloxane matrix. A hard coat that is often used is a product obtained by coating a partially hydrolyzed condensate of a silane coupling agent having an epoxy group with colloidal silica or by adding a resin group polyfunctional epoxy compound to it and baking it. . The acrylic hard coat is generally one in which a mixture of a polyfunctional acrylic acid ester and its prepolymer is applied and cured by irradiation with ultraviolet rays. In some cases, colloidal silica or a colloidal silica whose surface is treated with a silane coupling agent containing a methacryloxy group, a titanium coupling agent, or a long-chain alcohol may be added. Both the silicone and acrylic hardcoats described above are suitable for use in the articles of the present invention.

In the present invention, the plastic article coated with the above-mentioned thin film of an inorganic substance preferably has a layer of a certain polymer substance formed on its surface in order to improve the smoothness of the surface.

This polymer substance means oils and fats, and paraffin, silicone oil, grease, freon oil and the like are preferably used. The layer of the polymer substance is provided on the above-mentioned inorganic thin film, and this is the uppermost layer. Since this layer is made of a soft material, if this thickness is too thick, traces will remain when an object comes into contact with it, and it will also affect the optical properties of the inorganic optical thin film, so the average thickness of this layer should be as thin as possible. Is preferably 20 nm or less, more preferably 0.5 to 1.0 nm.

The following method is used to form an ultra-thin layer of the above-mentioned fats and oils. That is, the oil or fat as described above is brought into contact with the surface of a plastic article on which an inorganic thin film is formed by vacuum deposition.
In this state, it remains thick, so wipe off or wash it to remove excess oil and fat. Through the above steps, a polymer substance layer having a film thickness of 20 nm or less can be formed. The layer of polymeric material is strongly bonded to the surface of the freshly deposited, highly active inorganic thin film by the ion beam and remains even after cleaning to remove excess polymeric material. .

By providing this polymer material layer as the outermost layer, it is possible to reduce a large friction coefficient caused by the surface structure of the inorganic thin film.

<Operation> According to the present invention, the inorganic thin film on the plastic substrate has cracks that have been inevitable in the past due to the difference in the coefficient of thermal expansion from the plastic substrate when the temperature rises during use. Occurrence can be suppressed. Further, since this inorganic thin film itself is formed by ionization vapor deposition, it has a large cohesive force, and therefore high scratch resistance can be obtained.According to the present invention, the scratch resistance and heat resistance of the inorganic thin film on the plastic substrate are conflicting with each other. It is possible to improve both of the characteristics.

<Example> 1. A silicone hard coat material composed of a partial hydrolyzate of methyltrimethoxysilane and colloidal silica on a plate (made by Mitsubishi Rayon Co., Ltd.) of polymethylmethacrylate (PMMA) of 5 mm thick and 10 cm square. (Tosgard: Toshiba Silicone Co., Ltd.) was applied by a dipping method and baked at 80 ° C. for 2 hours to prepare a hard-coated PMMA plate.

This hard coat PMMA plate was attached to the substrate dome in the vacuum evaporation system, the pressure was reduced to 1.0 × 10 ^-5 Torr, and argon ions were used using a Kaufman type ion gun (KP-80 manufactured by Vacuum Instrument Co., Ltd.). Was radiated with a power of 1 KV × 100 mA for 5 minutes toward the surface of the hard-coated PMMA plate to be vacuum-deposited.
The energy density was about 20 μA per cm ² surface area of the PMMA plate. Next, the gas introduced into the ion gun is argon / oxygen =
While changing to a mixed gas of 9/1 and irradiating with a power of 500 V × 50 mA (energy density 10 μA / cm ² ), Yb ₂ O ₃ −Ta ₂ O ₅ −SiO
Deposition was performed in the order of ₂ . Here, the Yb ₂ O ₃ layer is at a speed of 5 angstroms per second, and nd = 125 nm, and the Ta ₂ O ₅ and SiO ₂ layers are at 20 seconds per second.
Nd = 250 nm and nd = 1 at Angstrom speed, respectively
25 nm was deposited.

After vapor deposition is completed, the vacuum chamber is returned to normal pressure, the vapor deposited PMMA plate is taken out, the surface is coated with silicone grease and then wiped off, and after being wiped clean with ligroine, the trichlene bath and the Freon vapor bath are included. It was washed through the washing line of 7 tanks.

Slip on the surface of PMMA plate that has been cleaned is good.
The average thickness of the silicone grease layer on the surface of the MA plate is about 2n.
m. Add 5kg of steel wool to it
It didn't hurt even after making 20 round trips. In addition, no change was observed even if it was placed in an air oven set at 80 ° C for 10 minutes. Then, this PMMA plate had a reflectance of 1.0% at the time of vertical incidence with respect to light having a wavelength of 510 nm.

2.65mm diameter CR-39 eyeglass lens (Heil
Cous , HOYA Co., Ltd.)
Reacrylate, pentaerythritol tetraacryle
Dipentaerythritol hexaacrylate
Ethylene glycol diacrylate, ethylene glycol
Ludiacrylate, 2-ethylhexyl acrylate, etc.
Azobisii as a partial prepolymer of acrylic acid esters
Sobutyronitrile and benzoin methyl ether and fluorine
Apply a small amount of surfactant by spin coating.
Cloth, and irradiate it with ultraviolet light using a high-pressure mercury lamp to cure it.
Then, a hard coat lens was produced.

This hard coat lens was attached to the substrate dome in the vacuum evaporation system, the pressure was reduced to 3.0 × 10 ^-5 Torr, and the cold cathode ion gun (Denton Vacuum Co., Ltd.
CC-101B) for power supply of argon ion 80
Irradiation was carried out for 10 minutes at 0V × 800mA and bias power supply 100V × 100mA. The energy density was about 200 μA / cm ² .
Next, change the gas introduced to the ion gun to oxygen and 1.0 × 10 ^-4 T
While irradiating ions at a pressure of orr, (energy density about 1
00μA / cm ² ) λ _O = 500nm, the film thickness nd at a constant deposition rate of 5 angstroms per second for all 5 layers.
= Λ _O / 12, each layer is laminated in the order of SiO ₂ , ZrO ₂ and SiO ₂ , then ZrO ₂ is nd = λ _O / 2, SiO ₂ is nd = λ _O / 4 and 5 layers are laminated. An antireflection film was formed.

When the vapor deposition is completed, the inside of the vacuum chamber is returned to normal pressure and the lens for which the vapor deposition is completed is taken out, and it is composed of 1 tank of Freon oil, 2 tanks of Freon solvent, and 1 tank of Freon vapor.
It was washed through the washing line of the tank.

The surface of the lens that had been cleaned had good slippage, and was not damaged even when it was reciprocated 20 times over 5 kg of steel wool. In addition, no change was observed even if it was placed in a constant temperature water bath set at 90 ° C for 10 minutes. The reflectance for light with a wavelength of 500 nm was 1.0%.

The lens with the five-layer antireflection film that had not been subjected to the Freon oil treatment did not have very good surface slippage, but no change was observed in the above-mentioned constant temperature water bath test, and the reflectance was the same. Had a value of.

Further, for comparison, when the irradiation of the ion beam, which was carried out at the same time as the vacuum deposition of the five-layer antireflection film, was stopped and the same treatment as in this example was carried out, the scratch resistance was almost the same as that of this example. Equally, the antireflective coating cracked in a 10 minute water bath test.

3. Apply a paint containing a copolymer of hydroxyethyl methacrylate and glycidyl methacrylate as a main component to a polycarbonate plate (made by Tsutsunaka Plastics Co., Ltd.) of 5 mm thickness and 10 cm square, and dry and cure it.
A silicone-based hard coat material (Tosguard; manufactured by Toshiba Silicone Co., Ltd.) containing a partial hydrolyzate of methyltrimethoxysilane and colloidal silica was applied and dried and cured.

This hard-coated polycarbonate plate was attached to the substrate dome in the vacuum evaporation system, the pressure was reduced to 10 × 10 ^-5 Torr, and argon ions were irradiated at 1 KV × 100 mA using a Kauffman type ion gun (Commonurus Miratron 3 cm type). It was irradiated with the power of 5 minutes. (Approximately 20 μA / cm ² ) Then, the gas introduced into the ion gun was changed to a mixed gas of Argan / oxygen = 9/1 (energy density of the ion beam was approximately 10 μA / cm ² ) and TiO ₂
Was deposited to 130 angstroms, the gas was changed to argon again to deposit silver to 300 angstroms, then the introduced gas was changed to argon / oxygen = 9/1 again to deposit TiO ₂ to 2500 angstroms, and finally SiO ₂ to 1250 angstroms. It was vapor-deposited.

The vapor-deposited polycarbonate plate was dipped in silicone oil, and then excess silicone oil was covered with 1 luan hexane and washed through a washing line of 7 tanks.

Slip on the surface of the polycarbonate plate that had been washed was good, and was not damaged even when the steel wool was reciprocated 20 times over 5 kg. In addition, no change was observed even if it was placed in an air oven set at 80 ° C for 10 minutes. The reflectance at normal incidence for light with wavelengths of 500 nm and 1000 nm was 2.0% and 80%, respectively.

4. In Example 3, except that the silicon-based hard coat-treated polycarbonate plate was irradiated with an ion beam alone in a vacuum vapor deposition apparatus, and the polycarbonate was heated in the vacuum vapor deposition apparatus at about 150 ° C. with an electric heater. About 1
When heated for 0 minutes and treated in the same manner as in Example 3 except above, the same surface slipperiness, scratch resistance, heat resistance, and antireflection performance as in Example 3 were exhibited.

<Advantages of the Invention> According to the present invention, it is possible to achieve both high heat resistance and high scratch resistance of a plastic substrate / inorganic thin film bonded body, which has been impossible in the past. As a result, it becomes possible to use a member in which various inorganic thin films are provided on a plastic substrate as a part of automobiles and other transportation equipment, a part of various optical devices, and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshiyuki Hanada, Inventor Yoshiyuki Hanada, 4-8 Doshomachi, Higashi-ku, Osaka City, Osaka (56) References JP-A-56-9906 (JP, A) JP 49-47910 (JP, B2)

Claims (7)

[Claims] 1. A coating with a polysiloxane coating composition
While coating the metal oxide thin film by vacuum deposition while irradiating the surface of the hardened plastic substrate with an ion beam, the deposition rate is 2 to 50% of the total optical thickness of the metal oxide thin film. A plastic article coated with a metal oxide thin film, characterized in that the initial period of film formation at a thickness is maintained at 10 angstroms per second at most, and thereafter the film formation rate is maintained at a value exceeding 10 angstroms per second. Manufacturing method. 2. The method for producing a plastic article according to claim 1, wherein the metal oxide thin film is an antireflection multilayer film. 3. The method for producing a plastic article according to claim 1, wherein the ion beam is irradiated at an energy density of 1 to 1000 μA per unit surface area of 1 cm ^{2 of the} plastic substrate. 4. The method for producing a plastic article according to claim 1, wherein the ion beam uses at least one kind of ion selected from nitrogen, oxygen, and argon. 5. The method for producing a plastic article according to claim 1, wherein after coating the metal oxide thin film, an oil layer is further formed on the surface of the film. 6. The method for producing a plastic article according to claim 5, wherein the layer of fats and oils has an average thickness of 0.5 to 10 nm. 7. The method for producing a plastic article according to claim 1, wherein the surface of the plastic substrate before being coated with the metal oxide thin film is previously irradiated with an ion beam.