JPH0315515A - Surface treating method for sheet - Google Patents

Abstract

PURPOSE:To easily manufacture a sheet and a film having surfaces with high gloss and optical sharpness by including the steps of spraying solvent capable of dissolving a sheet material on the surface of the sheet, and swelling the surface of the sheet. CONSTITUTION:A sheet is obtained by employing thermoplastic resin and un cured or semicured curable resin, calender molding, extrusion molding, casting molding, etc. Solvent is sprayed on the surface of the sheet by suitable means to be swollen. The solvent for swelling the sheet includes, for example, solubility parameter SP value as a scale of judging solubility, and solvent having the parameter near the SP value of the resin for forming the sheet is selected. For example, solvent such as toluene (8.9 of SP value), xylene (8.8 of SP value) is adapted for polyethylene (7.7 - 8.9 of SP value), polypropylene (9.2 - 9.4 of SP value). Then, the swollen sheet is passed through mirror-face rolls in a state heated to a glass transition point or lower of a sheet material or melting point or lower of crystalline resin.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for surface treatment of resin sheets and films (hereinafter collectively referred to as sheets), and in particular a surface treatment method for thermoplastic and curable resin sheets using mirror-finished rolls. This invention relates to a glossy surface treatment method.

(Prior Art) Sheets with gloss or patterns on their surfaces are widely used mainly to improve the appearance of other substrates by laminating them on the substrate. In particular, sheets whose surfaces have been treated to make them glossy are used as painted sheets and adhesive tapes such as protect tapes and vinyl tapes to be applied to the surfaces of articles to give the surfaces gloss.

How to treat the surface of the sheet to make it glossy. A thermoplastic sheet or an uncured curable sheet that has been shaped by calendering or casting is heated to the extent that the surface of the sheet melts. Pass through a mirror roll. A common method is to transfer the mirror surface of a roll onto a sheet. However, by the method using the mirrored roll described above,
Sufficient gloss. Furthermore, it is difficult to obtain sharp images.

(Problems to be Solved by the Invention) The present invention solves the drawbacks of the above-mentioned conventional methods, and its purpose is to provide a surface treatment method for a sheet that uses a mirror roll to give gloss to the surface of the sheet. The object of the present invention is to provide a method for obtaining a surface condition with higher gloss and sharpness.

(Means for Solving the Problems) The present invention is a sheet surface treatment method in which the surface of a thermoplastic resin sheet or an uncured or semi-cured curable resin sheet is polished using a mirror roll. Immediately before the sheet passes through the mirror roll, the method includes the step of spraying a solvent capable of dissolving the sheet material onto the surface of the sheet to swell the surface portion of the sheet. This achieves the above objective.

The sheet subjected to surface treatment in the method of the present invention is a sheet obtained by conventional calendering, extrusion shaping, casting, or the like. As for the sheet material.
Thermoplastic resins and uncured or semi-cured curable resins (including thermosetting resins, photocurable resins (for example, ultraviolet curable resins), etc.) are used. For example, polyolefins such as polyethylene and polypropylene; vinyl resins such as vinyl chloride resins and vinyl acid resins; urethane resins; acrylic resins; fluororesins such as polyvinylidene fluoride and tetrafluoroethylene; polyesters such as polyethylene terephthalate (PUT) Polyamides such as nylon; ethylene-hinyl acetate copolymers; ethylene-vinyl alcohol resins; chlorinated polyethylene and the like. Additionally, thermosetting resin compositions containing crosslinking agents such as acrylic resins containing reactive monomers and blocked isocyanates can also be used.

Used in the method of the present invention. A solvent capable of dissolving the sheet material is selected as the solvent for swelling the sheet. The solubility parameter (
Solubility Parameter (cal/
cTIY), hereinafter referred to as SP value), and compounds with similar SP values are highly compatible with each other. Therefore, it is preferable to select a solvent having an SP value close to that of the resin constituting the sheet. For example, polyethylene (SP value 7.7-8.9,
(The numbers in parentheses below indicate SP values) and polypropylene (9.2 to 9.4), toluene (8.9)
Solvents such as , xylene (8.8) are suitable. Vinyl chloride resin (9.1-9.6) and vinyl acetate (9.1-9.
Regarding 6). Ethyl acetate (9.1), tetrahydrofuran (9.1) and methyl acetate (9.6) are suitable. The sp4fi of acrylic resin varies depending on the type of molecule that becomes the ester, and its SP value ranges from 8.2 to 12.0.
is within the range of For acrylic resins with an SP value of about 8 to 9, the above-mentioned solvents are suitable;
For acrylic resins with p-values, solvents such as l,4-dioxane (10.0), acetonitrile (11.9), dimethylformamide (12.1) are suitable. Furthermore, it is desirable that these solvents volatilize quickly after mirror roll treatment. Solvents with lower boiling points are preferred.

The amount of solvent sprayed is preferably such that the resin swells from the sheet surface to a depth of 0.1 to 30 μm, usually 0.01 to 0.1 ml.
/c+fi. Because the amount of solvent sprayed is small. If the swelling depth is less than 0.1 μm, surface irregularities cannot be improved. If it is larger than 30 μm, resin may adhere to the mirror roll. After passing through the rolls, operations such as heating or leaving for a long time are required to remove the solvent. moreover. The volatilization of the solvent causes unevenness on the sheet surface.

The surface treatment of the sheet according to the present invention basically involves passing the sheet obtained by calendering, extrusion, or casting through a mirror roll. This can be done using conventional equipment. Immediately before the sheet passes through the mirror roll, the solvent is sprayed onto the surface of the sheet by suitable means. As a spray device. Any spraying device that can spray uniformly over the entire sheet surface can be used. The spray device is. Amount of solvent sprayed. It is installed in front of the mirror roll at a distance that takes into consideration factors such as sheet feeding speed. Spraying is performed so that the solvent is diffused into the sheet to the aforementioned depth once the sheet reaches the mirror roll. The diffusion time of the solvent depends on the temperature, humidity, and moisture content of the sheet, but it takes approximately 5 to 30 seconds to diffuse to the above depth. usually. Spraying is performed about ten seconds before the sheet reaches the mirror roll.

The mirror-finished roll used may be either a regular calender extrusion roll or a mirror-finished roll used in casting molding. For example, it is possible to use a metallic roll treated with a mirror finish, plated with chromium or the like, or treated with a fluorinated resin. The swollen sheet sprayed with the solvent is passed through a mirror roll while heated. To do this, either heat the mirror roll or... A heating zone is provided in front of the mirror roll. The heating temperature is the glass transition point of the sheet material (melting point for crystalline resins such as polyethylene, polypropylene, and nylon) or lower. In the conventional method, it was necessary to melt the sheet surface, which required heating the sheet surface above its melting point or glass transition point. In the present invention, since the sheet surface is easily deformed due to swelling, the above-mentioned low heating temperature is sufficient.

The pressing load of the mirror roll when the sheet passes through the mirror roll is preferably 0.1 to 5 kg/c++I.

(Effect) According to the method of the present invention. In this way, a sheet with a surface of high gloss and high sharpness, which could not be obtained by conventional methods, can be obtained. For example, in terms of image clarity. G is a measure of sharpness
D value is 1.0 or more, gloss, 20°θ specular reflection is 85
% or more sheets can be easily obtained.

(Example) The invention will be explained below with reference to examples.

Vinyl chloride resin (manufactured by Tokuyama Sekisui Kogyo, TSIIOO)
30 parts of dioctyl phthalate and 2 parts of lead stearate were added to 100 parts, and a sheet with a thickness of 50 μm was prepared using a calender. The surface of this sheet has a GD value of 0.
1. The 20° θ gloss is 20%. This sheet was sent to a mirror surface roll (the mirror surface was polished to a GD value of 1.2 and chrome plated) for surface treatment.

At this time. 0.1 ethyl acetate 15 seconds before rolling process
Spray onto the sheet at a rate of mR/c+fl. The temperature of the mirror roll was set to 60°C, and the pressing load of the mirror roll was 0.
．． It was set at 5kg/c+fl.

The image clarity of the surface of the obtained sheet was 1.2 in terms of GD value.
The 20°θ gloss was 86%.

Oku L. Ethyl alcohol was used as the spray solvent at a rate of 0.2 mR/cf. The process was the same as in Example 1 except that the temperature of the mirror roll was 70°C. The surface of the obtained sheet had a GD value of 1.2 and a 20°θ gloss of 85%.

The main resin sheet for the implementation team was a polyvinylidene fluoride sheet (manufactured by Showa Denko, thickness 50 μm, GD value 0.9, 20°θ)
45% gloss) and 0.02 mF of dimethylformacide as the spray solvent! /cffl and set the mirror roll temperature to 100°C. And the pressing load is 1.0kg/
Surface treatment was performed according to Example 1 with the setting of cnN. The surface of the obtained sheet had a GD value of 1.2 and a 20° θ gloss of 90%.

An acrylic resin sheet (manufactured by Kanebuchi Chemical Co., Ltd., Sunjurenshito; thickness 50 μm, GD value 0.
8, 20°θ gloss 46%). Using 0.1 cc/c+fl of ethyl acetate as a spraying solvent, spraying was carried out 10 seconds before the rolling process, and the surface treatment was carried out according to Example 1, with the specular roll temperature being 80°C. The surface of the obtained sheet had a GD value of 1.2 and a 20° θ gloss of 88%.

The comparative example was the same as Example 1, except that the solvent sprayed onto the pan was not used and the temperature of the mirror roll was 80°C. The surface of the obtained sheet had a GD value of 0.5. And the 20°θ gloss is 3
It was 6%. Compared to Examples 1 and 2, the sharpness of the image was better. It is clear that both the gloss and the gloss are very poor.

In addition, without using MJL wheat spray solvent, the pressing load of the mirror roll was reduced to 1.
The same as in Example 4 except that the weight was 5 kg/cTIl. The surface of the obtained sheet has a GD value of 0.8.2
The 0°θ gloss was 50%. Compared to Example 4. Sharpness. It is clear that both the gloss and the gloss are inferior.

(Effects of the Invention) According to the method of the present invention, sheets and films having such a high-gloss, bright-reflective surface can be easily produced. The present invention makes it possible to manufacture painted sheets and marking sheets with excellent appearance. When such a sheet is attached to the surface of a base material, the appearance is better than when it is painted. Furthermore, since this sheet has high sharpness on vertical surfaces that cannot be obtained with painting, it can be widely used as a painted sheet to replace various types of current painting.

that's all

Claims (1)

[Scope of Claims] 1. A sheet surface treatment method in which the surface of a thermoplastic resin sheet or an uncured or semi-cured curable resin sheet is gloss-finished using a mirror roll, wherein the sheet is coated with a mirror roll. A method for surface treatment of a sheet, comprising the step of spraying a solvent capable of dissolving the sheet material onto the surface of the sheet to swell the surface portion of the sheet immediately before passing through the sheet.