JPH05154441A - Smoothing method for coated film - Google Patents

Abstract

PURPOSE:To make a coated film smooth by giving a fine vibration to an unhardened coated film. CONSTITUTION:A length 4 of waviness of a coating liquid is decreased to make the coating film smooth by giving fine vibration directly or indirectly on a substrate 1 coated with the coating liquid. Ultrasonic wave is used as a method to give the vibration. As result, the coating film is simply made smooth without using solvent to reduce viscosity nor using a leveling agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for smoothing an uncured coating film and a method for obtaining a smoothed cured coating film.

[0002]

2. Description of the Related Art When an uncured coating film lacks smoothness, if it is cured as it is, the appearance becomes poor. For example, applying a hard coating agent or a protective coating agent on an optical disc,
When the cured coating film lacks smoothness during the application of the photoresist agent in the production of C, light scattering occurs due to waviness of the coating film, and the former causes a recording / reproduction error.
In the latter case, the circuit is not normally drawn, and the manufactured IC will malfunction.

Conventionally, in order to smooth the coating film, the viscosity of the coating material is adjusted by adding a solvent, or a so-called leveling agent such as a silicon compound is added to the coating material.

However, in the former case, there is a drawback that it is necessary to take a so-called setting time sufficiently and energy for solvent evaporation is required. Further, in the latter case, there is a drawback that it is difficult to adjust the added amount of the leveling agent. That is, when the addition amount is too large, the repellency of the coating film is induced against the original purpose, and when the addition amount is too small, the leveling action cannot be sufficiently exhibited.

[0005]

The problem to be solved by the present invention is that it is not always necessary to adjust the viscosity of the paint and to add a leveling agent to the paint, and to smooth the uncured coating film by mechanical means. To provide a cured coating film which is easily smoothed, thereby preventing defects as a product that occurs when the coating film lacks smoothness.

[0006]

It is well known that when a paint is applied, the coating film surface has irregularities.

The cross section of this coating film is shown in FIG.
The coating film is smoothed according to the following equation. That is, when the time at which the height difference (Δh) between the peak and the valley on the coating surface becomes _1/2 is t _1/2 ,

[0008]

## EQU1 ## t _1/2 = kηλ ⁴ / γh ₀ ³

[0009] Here, k = 0.001337, η = paint viscosity, γ = paint surface tension, h ₀ = average film thickness of coating film, and λ = wavelength of waviness. In the above equation, the inventors have paid attention to the fact that the smaller the wavelength of the swell is, the smaller t _1/2 is, and have solved the above problem.

That is, in order to solve the above-mentioned problems, the present invention provides a method for promoting smoothing of a coating film, which is characterized by giving a slight vibration to the uncured coating film.

In the method of the present invention, the substrate provided with the coating is directly or indirectly vibrated slightly, but ultrasonic waves are used as an efficient method.

In the case of the direct method, for example, as shown in FIG. 2, a plate-shaped ultrasonic oscillator is used and a substrate is placed thereon. After applying the coating material to the substrate with an applicator, ultrasonic waves are oscillated to vibrate the coating material through the substrate to smooth the coating material. After that, the oscillation may be stopped and the coating film may be heated, ultraviolet ray irradiation, electron beam irradiation or the like may be taken as a curing means suitable for the coating material.

In the case of the indirect method, a stage connected to an oscillator is provided as shown in FIG. 3, and a substrate is placed on the stage.
After applying the coating material to the substrate with an applicator, etc., ultrasonic waves are oscillated and the coating material is vibrated through the substrate from the stage to smooth the coating material. After that, the oscillation may be stopped and the coating film may be heated, ultraviolet ray irradiation, electron beam irradiation or the like may be taken as a curing means suitable for the coating material.

The shapes of the ultrasonic oscillator and the stage are not limited to those shown in the figures, and the method described in the present invention may be used.

[0015]

In the coating film obtained as described above, the wavelength of the initial waviness becomes small due to the microvibration, so before the microvibration,
If the undulation wavelengths after slight vibration are λ ₀ and λ, respectively, the time required for smoothing can be shortened to 1 / (λ ₀ / λ) ⁴ or less.

[0016]

EXAMPLES Examples will be shown below.

(Example 1) A flat type ultrasonic oscillator used in an ultrasonic cleaner "VS-100" manufactured by Inei Morieido Co., Ltd. was separated from the main body, and a glass substrate of 10 cm x 10 cm was used. It was placed on the oscillator. Next, with an applicator,
UV curing resin "EX" manufactured by Dainippon Ink and Chemicals, Inc.
-704 "was applied on the glass substrate so that the coating thickness was 5 µm, the ultrasonic oscillator was oscillated at an output of 100 W for 10 seconds, and after the oscillation was completed, the coating was cured by irradiating ultraviolet rays. .

When the obtained cured coating film was observed, a coating film having excellent smoothness was obtained.

(Embodiment 2) 10 cm × 1 on a circular stage attached to the horn tip of an ultrasonic homogenizer “5203” manufactured by Odake Co., Ltd. made of aluminum.
A 0 cm glass substrate was left standing. Next, an applicator was used to apply an ultraviolet curable resin “EX-704” manufactured by Dainippon Ink and Chemicals, Inc. on the glass substrate so that the coating film thickness was 5 μm, and then the ultrasonic oscillator was applied. Output 10
The film was oscillated at 0 W for 10 seconds, and after the oscillation was completed, ultraviolet rays were irradiated to cure the coating film.

Observation of the obtained cured coating film revealed that a coating film having excellent smoothness was obtained.

(Comparative Example 1) A 10 cm × 10 cm glass substrate was applied with an applicator to Dainippon Ink and Chemicals, Inc.
UV-curable resin "EX-704" manufactured by Japan
After coating, the coating was left to stand for 10 seconds and then irradiated with ultraviolet rays to cure the coating.

When the obtained cured coating film was observed, a wavy coating film was obtained.

[0023]

According to the method of the present invention, it is not always necessary to adjust the viscosity of the paint and to add a leveling agent to the paint, and it is possible to achieve smoothing of the uncured coating film in a short time and to easily smooth the paint. A cured coating film can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a cross section of a coating film immediately after coating.

FIG. 2 is a schematic view of a method of directly applying ultrasonic waves to a substrate to be coated.

FIG. 3 is a schematic view of a method of indirectly applying ultrasonic waves to a substrate to be coated.

[Explanation of symbols]

 1 Substrate 2 Paint Surface 3 Average Thickness of Paint 4 Wavelength of Ripple on Paint Surface 5 Ultrasonic Oscillator 6 Stage 7 Ultrasonic Oscillation Horn

Claims (2)

[Claims] 1. A method for promoting smoothing of a coating film, which is characterized by imparting a slight vibration to the uncured coating film. 2. The method according to claim 1, wherein an ultrasonic transmitter is used as a source of the slight vibration.