JPS62170901A - Production of specular molding made of synthetic resin - Google Patents

Abstract

PURPOSE:To improve the productive efficiency of the mirror board made of the synthetic resin by heating the board at a temp. range of T-(T+45 deg.C) on the basis of the softening point T deg.C of the thermoplastic resinous substrate, thereby thermoforming it. CONSTITUTION:In thermoforming the mirror board made of the thermoplastic resin, if the resin substrate is heated to the temp. of more than the softening point T of the resin substrate, a cloudiness generates on the mirror surface of the mirror board. The molded product 1 having a good mirror surface is obtd., recovering the original mirror surface having no cloudiness by heating the resin substrate at a temp. range of T-(T+45 deg.C) to effect a vacuum molding, a compression molding or a fold molding. The protective coating film softens together with the substrate by heating using a coating material made of a thermoplastic resin, as the protective coating film follows to a thermal contraction and an elongation of the substrate, without a hinderance, when molding it, a crack does not generate in a thin metallic film.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a thermoformed product of a mirror plate made of synthetic resin used for displays, wall panels, etc., and in particular, to produce a mirror surface by forming a metal thin film on one side of a synthetic resin substrate. The present invention relates to a method of manufacturing a thermoformed product which is manufactured into a predetermined shape by thermoforming the end plate.

Conventional technology and problems Synthetic resin mirrors use a synthetic resin board, especially an acrylic resin board with excellent transparency, as a substrate, and a thin film of aluminum or other metal is formed on the surface of the board by vacuum evaporation or the like. This gives it a mirror finish, and the surface is then protected with a coating of synthetic resin paint.

These synthetic resin mirrors are lightweight and hard to break.
Since it is easy to machine, it has been widely used in displays and decorative fields in recent years, but one problem is that when thermoforming is performed using conventional methods, the mirror surface becomes cloudy, which damages the mirror characteristics of the surface. It is recognized that it has certain drawbacks.

This is true, for example, in Japanese Patent Application Laid-Open No. 51 (1973), which the present applicant proposed earlier.
This can be seen from the technique disclosed in Japanese Patent No. 63325, in which the mirror surface is made matte by heating a mirror made of synthetic resin to a temperature higher than the softening temperature of the resin.

Conventionally, in order to solve the above-mentioned problems, in order to make it possible to thermoform a synthetic resin mirror without causing fogging on the mirror surface, Japanese Patent Publication No. 56-45121 discloses that a synthetic resin substrate is formed on the glass in advance. It has been proposed that after heat treatment to a temperature higher than the transition temperature, a thin metal film is formed on the surface of the mirror to obtain the desired thermoformable synthetic resin end plate.

However, when this conventional method is used, it takes a relatively long time to preheat the synthetic resin substrate, which is not only troublesome but also has the drawback of reducing the manufacturing efficiency of the synthetic resin end plate.

This invention was developed by selecting a thermoplastic resin paint for the protective coating as a result of various tests and research aimed at obtaining the desired thermoformed product by thermoforming a synthetic resin mirror plate without causing fogging. By performing thermoforming at a predetermined temperature range that is relatively lower than the general thermoforming temperature of thermoplastic synthetic resin substrates, the fogging that occurs on the mirror surface due to heating is eliminated by molding, and the original They were able to restore the mirror surface and discover the scales, and were able to complete the work based on this knowledge.゛Means for Solving the Problems For the above purpose, the present invention provides a mirror plate made of synthetic resin by forming a metal thin film on one side of a thermoplastic resin substrate, and further forming a protective coating of thermoplastic resin paint on the surface. After manufacturing, the mirror plate is heated to a temperature in the range of T to T+45°C relative to the softening temperature T'C of the thermoplastic resin substrate and thermoformed. The gist is the method.

Thermoplastic resins used for the above resin substrate include polymethyl methacrylate resin, polyvinyl chloride resin, ABS
Examples include, but are not limited to, resins, polycarbonate resins, and the like. Although a colorless transparent plate is generally used, a colored transparent plate may also be used, and if a transparent resin paint is used for the protective coating, the use of a colored opaque plate is also permissible.

The metal thin film formed on the surface of the resin substrate is formed by means such as vacuum evaporation, sputtering, ion blating, plating, etc. using metals such as aluminum, chromium, nickel, and tin, but most commonly aluminum is used. It is formed as a vacuum-deposited thin film.

The protective film of the metal thin film is formed with a thermoplastic resin paint such as acrylic, urethane, or vinyl chloride, but in order to thermoform the synthetic resin head plate, it is necessary to apply a coating at a temperature between the softening temperature of the substrate T and T + 45°C. It is necessary to use a resin coating that can be simultaneously softened when heated to a certain temperature range. Therefore, it is preferable to select and use a resin paint having a softening temperature comparable to that of the resin of the substrate. The protective film can be formed by, for example, spraying or painting the above-mentioned paint.

The synthetic resin end plate obtained by forming a metal thin film and a protective wave film on a resin substrate is then subjected to thermoforming such as vacuum forming, pressure forming, and bending to form a molded product into a desired shape. However, if the heating temperature during thermoforming is below the softening temperature T''C of the resin of the substrate, molding cannot be performed. If the mirror is heated to a temperature close to , clouding occurs on the mirror surface, and this clouding remains even after molding, making it impossible to achieve the intended purpose of the present invention.

A particularly suitable thermoforming temperature is the softening temperature T'C of the resin of the substrate.
However, it is generally in the range of T+10 to 35℃, and more specifically, if the substrate is made of acrylic resin, T+15℃
~35°C, or T+10°C in the case of vinyl chloride resin
The temperature range is about 30°C.

Function: According to the method for manufacturing a mirror molded article according to the present invention, when thermoforming a synthetic resin mirror plate, the mirror surface is once fogged by heating it to a temperature higher than the softening temperature of the resin substrate. However, since the heating temperature is in the range of T to T + 45°C, when processing such as vacuum forming, pressure forming, bending forming, etc. is restored, and a molded product with a good mirror finish can be obtained.

The reason why the mirror surface is restored by molding in this way is not clear, but it is speculated as follows.

In other words, when a synthetic resin mirror plate is heated to a temperature higher than the softening temperature of the synthetic resin of the substrate, the internal stress of the thermoplastic synthetic resin substrate during sheet production is gradually released and it contracts, but the thin metal film on the surface shrinks due to the shrinkage. It cannot follow the pattern and therefore wrinkles occur. This tendency becomes more pronounced as the heating temperature increases, and develops into cracks when the heating temperature exceeds T+45° C. relative to the softening temperature T'C of the substrate. However, it is thought that if the wrinkles are caused by heating to a temperature 45°C higher than the softening temperature of the substrate, that is, below T+45°C, the wrinkles are stretched by thermoforming and returned to their original state. .

In addition, by using thermoplastic resin paint for the protective coating, it softens together with the substrate due to the above heating and follows the heating shrinkage of the substrate and elongation during molding without any problem, causing cracks in the metal thin film. This is probably because there is nothing to do. This can be confirmed by comparing the fact that when a thermosetting resin paint is used for the protective coating, cracks occur in the metal thin film and the mirror surface is not restored even after molding.

Effect of invention 9. ) According to the present invention, it is possible to obtain a mirror-molded product made of a synthetic resin and having a good specular reflection characteristic without clouding on the surface. Moreover, in order to manufacture this molded product, there is no need for any special additional processes from the creation of the end plate to thermoforming, and the desired purpose can be achieved simply by controlling the thermoforming temperature conditions. This has the advantage that synthetic resin mirror molded products can be produced easily and efficiently.

Examples Example 1 Aluminum was vacuum deposited on one side of a transparent methyl methacrylate resin plate (trade name "Sumipex E", manufactured by Tsutsunaka Plastic Industry Co., Ltd.) having a thickness of 2-0Ml5 and a softening temperature of 85°C to form a metal thin film. Furthermore, acrylic resin paint (product name "Plus Coat J#64-") is applied on this metal thin film.
16, Toho Kaken Co., Ltd.) spray coated to a thickness of 20μ
A protective film was formed.

A plurality of samples of the synthetic resin mirror plates obtained in this way were
A molding test was conducted by heating to 0°C, 100°C, and 120"C to 1140°C. This molding test was performed using a vacuum forming method, and as shown in Figures 1 and 2,
In molding the molded product (1) by arranging the substantially square unit bulges (2) in the base pattern of wX150, the molding depth is H.
) was set to 10mK1.

Then, the moldability and specularity of the surface of the molded product were evaluated, and the results are shown in Table 1. Here is the evaluation of specularity:
A sample whose surface maintained a good mirror surface after molding was not matted was marked with an O mark, and a case where clouding had occurred was marked with an x mark. In addition, for the evaluation of formability, those that could be formed to a depth of 10 or more without cracking the metal thin film were marked 0, and those that could not be formed to a depth of 10 mm were marked 0. Indicated by an X.

Table 1 Examples A transparent polyvinyl chloride resin board (product name: Sunroid Uni, G1
70J (manufactured by Tsutsunaka Plastic Industry Co., Ltd.), a synthetic resin end plate was made in the same manner as in Example 1, and heating temperatures were set to 55°C, 70°C, 90°C, and 120°C.
Thermoforming tests were conducted at various temperatures. The results are shown in Table 2. Note that, except for the heating temperature, other molding conditions and evaluation methods were the same as in Example 1.

Table 2 Comparative Examples A synthetic resin end plate was made in the same manner as in Example 1, except that the protective film was formed using an alkyd resin paint, and the same thermoforming test as above was conducted.The results are as follows. It was as shown in Table 3.

Table 3

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of the form of a synthetic resin mirror molded product according to the present invention, and FIG. 2 is a sectional view taken along the line 1--2 in FIG. (1) Molded product, (2) Unit bulge.
Pa or above

Claims (1)

[Claims] After forming a metal thin film on one side of a thermoplastic resin substrate and further forming a protective film of thermoplastic resin paint on the surface to produce a synthetic resin mirror plate, the mirror plate is heated to the softening temperature of the thermoplastic resin substrate, T°C. 1. A method for producing a mirror molded product made of synthetic resin, which comprises thermoforming by heating to a temperature in the range of T to T+45°C.