JPH0416429B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field] The present invention relates to a method of manufacturing a lens by applying a liquid composition to a lens base material by spin coating to form a thin film. [Prior Art] A dipping method or a spin coating method is known as a method of forming a thin film by applying a liquid composition to a lens base material, followed by drying and heat treatment. It is widely used for forming thin films of inorganic oxides and coating resists on glass and silicone wafers. JP-A-58-46301 describes a method for producing a two-layer antireflection film using a liquid composition. This document discloses an example of a method in which both the first layer and the second layer are dip coated, and a method in which both the first layer and the second layer are spin coated. Other known examples include, for example, Japanese Patent Application Laid-Open No. 57-77029
The publication describes a tungsten oxide thin film,
Publication No. 135713 discloses a method of forming a silicon oxide film by dip coating or spin coating. Furthermore, as a publicly known example close to the present invention, there is
-109772 and JP-A-58-205148. In both of these inventions, a silicon wafer is rotated, a resist is dropped onto the center of the silicon wafer, and nitrogen gas is sprayed from vertically upward toward the center of the wafer. Still another known example is a method in which a substrate is placed in a concave support means and spin coated (Japanese Patent Laid-Open No. 54-4936). [Problems to be Solved by the Invention] However, in the spin coating method disclosed in Japanese Patent Application Laid-open No. 58-46301, a substrate is adsorbed onto the rotating surface of a spinner, a liquid composition is dropped, and the spinner is rotated to coat the substrate. There is a method of forming a thin film on the surface, or a method of immersing the substrate in a liquid composition and then applying spin coating to make the coating film uniform in thickness. There is a difference in film thickness between the center of rotation of the material and the end portions of the base material, resulting in uneven reflection interference color and total light transmittance, resulting in the problem that only products with low commercial value can be obtained. JP-A-57-77029, and JP-A-57-
Publication No. 135713 also has the problem that a uniform coating film cannot be obtained over a wide area due to the low accuracy of film thickness control, as described above. In particular, in the spin coating method in which drying and curing are carried out while rotating, there is a problem that unevenness tends to occur in the film thickness between the center of rotation and the ends. JP-A-54-109772 and JP-A-58-
The technique disclosed in Japanese Patent Publication No. 205148 grips the base material at its lower surface, so although it is possible to coat only the upper surface of the base material, it is not possible to coat the lower surface or both surfaces of the base material at the same time. Furthermore, in the conventional technique, since the lower surface of the base material has a gripping means for the base material, or a gripping means and a rotation transmission means, it is difficult to renew the gas, and it is difficult to uniformly apply the paint to the lower surface of the base material. was difficult. Furthermore, the technique disclosed in JP-A-54-4936 is a method in which the base material is simply placed in a concave support means and then spin-coated, and there is no mechanism for gripping from the periphery, so the coated surface of the base material does not come into contact with the support. However, there were problems in that not only was it impossible to form a uniform coating, but even if the gas were to be blown from the bottom, the base material would lift up. An object of the present invention is to provide a gripping means having a force to move the periphery of the substrate from the periphery toward the center of the substrate in the above-mentioned prior art spin coating technique, and to
To provide a technique for uniformly applying a paint to the lower surface or both surfaces of a substrate by spraying gas from at least the lower surface of the substrate. Furthermore, it is an object of the present invention to provide a method for manufacturing a lens having a uniform thin film without unevenness in film thickness at each part of the base material, which eliminates the drawback that the film thickness tends to be uneven between the center of rotation and the end parts. . [Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. "In a method for manufacturing lenses by a spin coating method in which a thin film is formed on the surface of a lens substrate while rotating a lens substrate coated with a liquid composition for forming a thin film, at least a part of the side surface of the substrate is A lens characterized in that the lens is gripped by a gripping means having a force directed from the periphery toward the center, and while the base material is rotated, a gas is blown onto at least the lower surface of the surface of the base material coated with the liquid composition to form a thin film. The lens base material as used in the present invention is a lens base material made of glass or plastic, and its shape is not particularly limited. Also,
The base material is coated with a coating material in advance,
For example, when a plastic lens is used as a base material, a coating material may be applied to the lens to improve or impart various physical properties such as adhesion, hardness, chemical resistance, durability, and dyeability. The liquid composition for forming the film on the above-mentioned base material may consist of only a film-forming substance, and may also contain various volatile solvents to provide the necessary coating workability, and various volatile solvents to improve the flow during coating. Those containing a surfactant can also be used. From the viewpoint of applying a liquid composition, the film-forming substance is not particularly limited as long as it can be dispersed or dissolved in a solvent to form a liquid composition and then dried to form a film. On the other hand, materials that are liquid themselves can be used alone, but they can also be diluted with an appropriate solvent, and it is also possible to use a mixture of two or more of these materials. be. Here, the liquid composition is a composition having a viscosity within a range that can be applied in ordinary coating operations, and is 100 centipoise or less, preferably 10 centipoise or less at the application temperature. That is, it is difficult to obtain a uniform coating film with a liquid composition having a viscosity higher than this. The above liquid composition can form a film with a thickness of 0.02 to 5 μm, preferably 0.02 to 0.2 μm.
The effect of the present invention is exhibited in the formation of thin films. The thin film of the present invention is not limited to a single layer, but can be formed into a multilayer of two or more layers by performing multiple treatments. In particular, for antireflection thin film products, it is preferable to form a thin film consisting of two layers. Regarding the refractive index and film thickness of each layer, for example, in the case of two layers, the layer on the transparent substrate side (first layer) The refractive index is 0.03 or more higher than the refractive index of any of the transparent base material in contact with this and the second layer provided on the first layer,
The second layer needs to be composed of a transparent base material and a coating having a lower refractive index than the first layer, and
An antireflection lens having a reflective interference color can be obtained by applying the film as a layer to a thickness of 20 to 1000 nm. In the present invention, the fixation of the base material for applying the above-mentioned liquid composition to at least the lower surface or both sides of the base material is carried out by means of a chuck mechanism that is equipped with a claw for fixing the base material and can withstand high-speed rotation (as shown in FIG. 1). It is possible to use an apparatus equipped with a means for gripping the substrate) and a nozzle capable of spraying gas onto the surface of the substrate. That is, first, the spring push-up member 7 shown in FIG. Then, due to the contracting force of the tension coil spring 5, the lower part A of the base material fixing claw closes (moves to the axial center) using the base material fixing claw attachment pin 3 of the claw support disk 4 as a fulcrum, and the base material fixing claw 1 closes. open. Next, when the base material 10 is inserted into the base material fixing claw 1 and the spring push-up member 7 is lowered, the base material fixation claw lower part A is fixed to the claw fixing plate B of the spring push-up member 7 by the force of the compression coil spring 6. At the same time, the base material 10 is fixed to the base material fixing claws 1. That is, the base material 10 is gripped by the force directed toward the center of the fixing claw 1. Further, as is clear from FIG. 1, the fixing claw 1 grips the base material 10 around the base material 10, and does not substantially contact the surface to which the paint is applied. In other words, there is no contact between the front and back sides. This has the advantage that the optical surface of the lens will not be damaged or become uneven. Next, in the present invention, gas C is sprayed onto the back surface of the base material 10 from the gas supply pipe 9 through the gas spray nozzle 2. The position at which the gas is sprayed by the nozzle 2 is preferably at least the lower surface of the base material and at the substantial center of the base material, as shown in FIG. The reason for this is, firstly, in the conventional technology, the lower surface of the base material has a gripping means for the base material, or a gripping means and a rotation transmission means, so it is difficult to renew the gas.
It was difficult to uniformly apply the paint to the lower surface of the substrate. Therefore, it is very important to spray gas onto the coating surface of the lower surface of the substrate to promote the diffusion of the solvent and the like. Second, the center of the rotating base material tends to dry and harden more slowly than the surrounding areas, and the film thickness tends to be thinner, so by spraying gas, this can be improved and uniformly cured. This is to obtain a film with a certain thickness. Also, depending on the conditions, the film may become thicker in the center of the base material, but this can also be improved by blowing gas. In addition, in the present invention, the gas spray nozzle 2
may also be provided above the base material 10 and coated with paint from both sides. Rotation is achieved by connecting the entire device shown in FIG. 1 to a rotating shaft through a shaft coupling 8. Methods for applying the liquid composition onto the surface of the substrate include immersing the substrate in the liquid composition and then spin coating, applying the liquid composition while rotating the substrate, and applying the liquid composition to the substrate. A method of applying the liquid composition simultaneously with the rotation of the base material, or a method of applying the liquid composition before the rotation of the base material, etc. can be applied. The gas referred to in the present invention preferably includes nitrogen, which is a representative inert gas, and air, preferably dehumidified air, and nitrogen or air containing solvent vapor in the liquid composition is also preferably used. As a spin coating condition in the present invention, the rotation speed is 200 rpm or more, preferably 500 rpm or more.
Any known means may be used to perform such rotation. Further, the time required to reach the maximum rotational speed is 0.3 seconds or more, preferably 0.5 seconds or more. That is, if the rotational speed is lower than this, the effect of making the thin film uniform by gas blowing cannot be obtained. Changes in rotational speed, type of gas to be sprayed, temperature of the gas to be sprayed, duration of spraying, and timing of spraying should be determined experimentally depending on the composition of the liquid composition and atmospheric conditions. The amount of gas sprayed is 20/min or less, preferably 10/min or less; if the amount of gas is too large, the coating film will be non-uniform. Any known means may be used as the gas flow rate adjusting means. In addition, the spraying location and rotation time should be determined experimentally so that the coating film thickness is uniform and constant, taking into account the composition and atmosphere of the liquid composition, product variations, and productivity. [Example] The content of the present invention will be explained below by way of an example, using a method for forming an antireflection film for a lens, but the present invention is not limited thereto. Example 1 (1) Preparation of first layer coating composition 479 g of n-butyl alcohol, 8.2 g of acetic acid, and 0.17 g of silicone surfactant are added to a beaker equipped with a rotor. A coating composition was prepared by adding 31.6 g of methanol-dispersed colloidal silica and 23 g of tetra-n-butyl titanate to this mixed solution while stirring at room temperature. (2) Preparation of second layer coating composition (a) Preparation of silane hydrolyzate 13.7 g of γ-glycidoxypropyltrimethoxysilane, 5.8 g of vinyltriethoxysilane
4.8 g of a 0.05N hydrochloric acid aqueous solution was added dropwise to 24.3 g of n-propyl alcohol and mixed with stirring while controlling the temperature at 10°C. After the dropwise addition was completed, the mixture was further stirred at room temperature for 1 hour to obtain a silane hydrolyzate. (b) Preparation of coating composition 207.4 g of n-propanol, 98.4 g of water were added to 44.2 g of the above silane hydrolyzate while stirring;
31.8 g of ethyl cellosolve, 36.7 g of the same methanol-dispersed colloidal silica used in (1) above.
g, add 0.25 g of silicone surfactant and 1.1 g of aluminum acetylacetonate,
A coating composition was obtained by thorough stirring and mixing. (3) After coating and soaking in a caustic soda aqueous solution, a washed diethylene glycol bisacrylic carbonate polymer lens (diameter 75 mm, thickness 2.1 mm, CR-39 plano lens) was placed in the first layer coating composition prepared in (1) above. After immersing the lens substrate in the water, the bottom surface (inner surface ) was spin coated. Spin coating conditions Immersion time in coating composition: 10 seconds Setting time: 5 seconds Rotation speed: 3500 rpm Time to reach maximum rotation speed: 3 seconds Rotation time: 30 seconds Gas (nitrogen) spray amount: 3/minute Gas spray timing: Gas spraying position at the same time as the start of rotation: Approximately the center of the concave surface of the lens Indoor temperature: 20°C The coated lens was heated and dried at 93°C for 0.75 hours. After heating, immerse in hot water at 50℃ for 0.5 hours,
It was washed with water, and water droplets adhering to the surface immersed in acetone were removed. Thereafter, heat drying was performed at 110° C. for 1 hour to obtain a first layer. The thickness of the first layer obtained was 87 nm. On the obtained first layer, the second layer coating composition prepared in (2) above was further spin-coated under the same conditions as the first layer, and the coated lens was cured by heating in a hot air dryer at 93°C for 4 hours. I did this. The thickness of the second layer obtained was 98 nm. Table 1 shows the total light transmittance and reflection interference color of each part of the obtained lens, and the film thickness of the second layer. The lens used is a circular lens as shown in the front view in FIG. 2 and the cross-sectional view in FIG.
The concave surface 14 was referred to as the concave surface 14, and measurements were taken at each portion. The total light transmittance of the central part 11 and end parts 12 is 96.6%, the film thickness of the convex surface 13 and concave surface 14 of the lens is both 98 nm, and each part and each surface has a uniform reflective interference color of reddish-purple. A lens with no unevenness on the entire surface was obtained. The total light transmittance of the uncoated lens was 92.4%. Example 2 Using the same coating composition as Example 1,
The first layer and the second layer were spin coated under the following conditions. The equipment shown in Figure 1 was used. Spin coating conditions Immersion time in coating composition: 10 seconds Setting time: 5 seconds Rotation speed: 4000 rpm Time to reach maximum rotation speed: 2 seconds Rotation time: 30 seconds Gas (air) spray amount: 6/minute Gas spray timing: Gas spraying position at the same time as the start of rotation: Approximately the center of the concave surface of the lens Indoor temperature: 20°C The processing conditions for the coated first and second layers were the same as in Example 1. There is almost no difference in the total light transmittance and reflection interference color of each part of the obtained lens, and the film thickness of the second layer. A lens with a uniform purple reflective interference color and no unevenness over the entire surface was obtained. Also
Total light transmittance between 20 lenses is ±0.2%
The variation was less than 1,000 yen, and almost no reflection interference color was observed. Comparative Example 1 Using the same coating composition as Example 1,
The first layer and the second layer were spin coated under the following conditions without blowing gas (nitrogen). Spin coating conditions Immersion time in coating composition: 10 seconds Setting time: 5 seconds Rotation speed: 3500 rpm Rotation time: 30 seconds The coated lens was treated under the same conditions as in Example 1. The total light transmittance at the center of the obtained lens is
It was 96.5%, but there was a difference of 1.0% between the center and the edges. Also, the reflection interference color of the convex surface of the lens is bluish-purple, but the reflection interference color of the concave surface is pale yellow.
Reflection interference color unevenness was observed in some parts of each surface. Comparative Example 2 Using the same coating composition as Example 1,
The first layer and the second layer were spin coated under the following conditions without blowing gas (nitrogen). Spin coating conditions Immersion time in coating composition: 10 seconds Setting time: 5 seconds Rotation speed: 4000 rpm Room temperature: 20°C The coated lens was treated under the same conditions as in Example 1. The total light transmittance at the center of the obtained lens is
The difference was 95.8%, but there was a difference of 1.5% between the center and the edges.Also, while the reflective interference color of the convex surface was reddish-purple, the reflective interference color of the concave surface was pale yellow. Due to this, reflection interference color unevenness occurred. There was also a ±0.5% variation in total light transmittance among the 20 lenses, and the reflected interference color was uneven and varied from pale yellow to blue-purple.

[Table] [Effects of the Invention] The present invention solves the drawback that the spin coating method tends to cause unevenness in the film thickness between the center of rotation and the ends, and provides a coating with no unevenness in the film thickness at each part of the base material.
A special effect is obtained in that a lens having a uniform thin film can be obtained. Further, the gripping means does not come into contact with substantially the paint-applied surface, that is, the front and back surfaces. This has the advantage that the optical surface of the lens will not be damaged or become uneven. We also manufacture products with uniform thickness such as lenses, antireflection plates for televisions, printed wiring boards, shadow masks, silicone wafers, and planar semiconductor devices.
Furthermore, it can be effectively used industrially in fields where extremely thin films are required.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a chuck device equipped with a base material fixing mechanism and a gas spraying function in the spin coating method used in the present invention, and FIG.
FIG. 3 is a front view and a sectional view of the base material (lens). 1: Base material fixing claw, 2: Gas spray nozzle,
3: Claw mounting pin for fixing the base material, 4: Claw support disk,
5: Tension coil spring, 6: Compression coil spring, 7:
Spring push-up member, 8: Shaft joint, 9: Gas supply pipe, 10: Base material, 11: Lens center portion, 12: Lens end portion, 13: Lens convex surface portion, 14: Lens concave surface portion.

Claims (1)

[Scope of Claims] 1. In a method for manufacturing lenses by a spin coating method in which a thin film is formed on the surface of a lens substrate while rotating a lens substrate coated with a liquid composition for forming a thin film, the side surface of the substrate is gripping at least a portion of the base material with a gripping means having a force directed from the periphery toward the center;
A method for producing a lens, which comprises rotating the base material and spraying gas onto at least the lower surface of the base material surface coated with a liquid composition to form a thin film. 2. A method for applying a liquid composition to a lens base material is
The method is selected from a method of dipping the substrate in the liquid composition or applying the liquid composition to the substrate before rotating the substrate, a method of applying the liquid composition simultaneously with the rotation of the substrate, and a method of applying the liquid composition while the substrate is rotating. The method for manufacturing a lens according to claim 1, characterized in that the method is one or more methods. 3. The method for manufacturing a lens according to claim 1, wherein the position where the gas is sprayed is substantially at the center of the lens base material. 4 The speed at which the lens base material is rotated is the rotation speed.
2. The method for manufacturing a lens according to claim 1, wherein the speed is 200 rpm or more. 5. The method for manufacturing a lens according to claim 1, wherein the amount of gas blown is 20 times per minute or less. 6. The method for manufacturing a lens according to claim 1, wherein the gas is selected from nitrogen or air. 7. The method for manufacturing a lens according to claim 1, wherein the lens base material is mainly composed of plastic or glass. 8. The method for manufacturing a lens according to claim 1, wherein the liquid composition has a viscosity of 100 centipoise or less. 9. The method for manufacturing a lens according to claim 1, wherein the thin film formed has a thickness of 0.02 to 5 μm.