JPH0785727B2 - Synthetic resin mirror molding product manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermoformed product of a synthetic resin end plate used for a display, a wall interior, etc., and particularly to a mirror surface by forming a metal thin film on one surface of a synthetic resin substrate. And a thermoforming mirror product manufactured into a predetermined shape by thermoforming this end plate.

Conventional technology and problems Synthetic resin mirrors use a synthetic resin plate, especially an acrylic resin plate with excellent transparency in many cases, as the substrate, and form a thin film of aluminum or other metal on the surface of this substrate by vacuum deposition or the like. As a result, the surface is mirror-finished, and the surface is covered with a synthetic resin coating to protect it.

Such a synthetic resin mirror is lightweight and hard to break,
Since it can be easily machined, it has been widely used in the fields of displays and decorations in recent years. However, one problem is that when thermoforming is carried out by a conventional method, the mirror surface becomes fogged and the mirror characteristics of the surface are impaired. It is recognized that it has the disadvantages noted.

This is because, for example, Japanese Patent Application Laid-Open No. 51-6 has been previously proposed by the present applicant.
It can also be known from the technique disclosed in Japanese Patent No. 3325, that is, the technique in which a mirror made of a synthetic resin is heated to a softening temperature of the resin or higher to make the mirror surface matte.

Conventionally, with respect to the above-mentioned problems, in order to enable thermoforming of a synthetic resin mirror without causing fogging on the mirror surface, in Japanese Patent Publication No. 56-45121, a synthetic resin substrate is preliminarily glass-coated. It has been proposed that after heat treatment at a temperature equal to or higher than the transition temperature, a metal thin film is formed on the surface thereof to obtain a desired thermoformable synthetic resin end plate.

However, according to this conventional method, the preliminary heat treatment of the synthetic resin substrate requires a relatively long time, which is not only troublesome, but also has a drawback that the production efficiency of the synthetic resin end plate is lowered.

This invention aims to obtain a desired thermoformed product by thermoforming a synthetic resin end plate without causing fogging, and as a result of various tests and studies, a thermoplastic resin paint was selected as a protective film. As a precondition, by performing thermoforming in a predetermined temperature range that is relatively lower than the general thermoforming temperature of the thermoplastic resin substrate, the fog generated on the mirror surface due to heating is erased by molding, and the initial mirror surface is formed. It was discovered that the state could be restored, and it was completed based on such knowledge.

Means for Solving the Problems The present invention, in the above-mentioned object, forms a synthetic resin end plate by forming a metal thin film on one surface of a thermoplastic resin substrate and further forming a protective coating by a thermoplastic resin paint on the surface. After manufacturing, the end plate is softened at a temperature T ° C. of the thermoplastic resin substrate.
The present invention is directed to a method for producing a synthetic resin mirror-molded article, which comprises heating to a higher temperature in the range of 10 to 35 ° C. and thermoforming.

Examples of the thermoplastic resin used for the resin substrate include, but are not limited to, polymethylmethacrylate resin, polyvinyl chloride resin, ABS resin, and polycarbonate resin. In general, a colorless transparent plate is used, but a colored transparent plate may be used, and when a transparent resin paint is used for the protective film, the use of a colored opaque plate is allowed.

The metal thin film formed on the surface of the resin substrate is formed by means of vacuum deposition using a metal such as aluminum, chromium, nickel, tin, etc., sputtering, ion plating, plating in a narrow sense, etc. Is formed as a vacuum deposited thin film.

The protective film of the metal thin film is formed by a thermoplastic resin paint such as acrylic resin, urethane resin, vinyl chloride resin, etc., but the softening temperature of the substrate is T to T + 45 ° C for thermoforming synthetic resin end plate. It is necessary to use a resin paint that can be brought into a softened state at the same time when heated to the range. Therefore, it is preferable to selectively use a resin coating having a softening temperature similar to that of the resin of the substrate. The protective film can be formed by, for example, spray coating the above paint.

The synthetic resin end plate obtained by forming the metal thin film and the protective coating on the resin substrate is then subjected to thermoforming such as vacuum forming, pressure forming, bending, etc. to obtain a formed product having a desired shape. If the heating temperature at the time of thermoforming is less than the softening temperature T + 10 ° C. of the resin of the substrate, the thermoforming is naturally difficult. However, when the temperature exceeds the softening temperature T ° C. and exceeds T + 35 ° C. to a temperature close to the normal thermoforming temperature, fog is generated on the mirror surface, and the fog remains even after molding. The intended purpose cannot be achieved satisfactorily.

Therefore, the thermoforming temperature should be in the range of T + 10 to 35 ° C with respect to the softening temperature T ° C of the resin of the substrate, and more specifically, T + 15 ° C to 35 ° C when the substrate is an acrylic resin, or In the case of vinyl chloride resin, it is preferable to set the temperature within the range of T + 10 ° C to 30 ° C.

Effect According to the method for manufacturing a mirror-formed product according to the present invention, when the synthetic resin end plate is thermoformed, it is heated above the softening temperature of the resin substrate, so that the mirror surface temporarily becomes cloudy. However, since the heating temperature is in the range of T + 10 to 35 ° C., if vacuum forming, pressure forming, bending forming or the like is subsequently performed under this heating state, the original fog does not occur due to the forming. The mirror surface is restored, and a molded product having a good mirror surface state can be obtained.

The reason why the mirror surface is restored by molding is not clear, but it is presumed as follows.

That is, when the synthetic resin end plate is heated above the softening temperature of the synthetic resin of the substrate, the internal stress at the time of plate production of the thermoplastic synthetic resin substrate is gradually released and shrinks, but the metal thin film on the surface does not shrink. It is unable to follow, and therefore wrinkles occur. This tendency becomes more prominent as the heating temperature increases, and cracks develop when the heating temperature exceeds T + 35 ° C. with respect to the softening temperature T ° C. of the substrate. However, the softening temperature of the substrate
It is considered that if the wrinkles are those up to a temperature higher by 0 ° C., that is, the wrinkles caused by heating at a temperature of T + 35 ° C. or lower, they are stretched by the thermoforming and returned to the original state.

In addition, the protective coating also uses a thermoplastic resin coating to soften it together with the substrate due to the above heating, and it follows the heat shrinkage of the substrate and the elongation at the time of molding without any hindrance, causing cracks in the metal thin film. It is thought to be because there is nothing to do. This can be confirmed by contrast with the case where when a thermosetting resin coating material is used for the protective film, cracks occur in the metal thin film and the mirror surface is not restored even by molding.

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a synthetic resin mirror-molded product having good specular reflection characteristics without surface fogging. Moreover, since the production of this molded product does not require any special additional steps from the production of the end plate to the thermoforming, the intended purpose can be achieved simply by controlling the thermoforming temperature conditions. In addition, there is an advantage that a synthetic resin mirror molded product can be manufactured easily and efficiently.

Examples Example 1 Aluminum was vacuum-deposited on one surface of a transparent methyl methacrylate resin plate (trade name "SUMIPEX E", manufactured by Tsutsunaka Plastic Industry Co., Ltd.) having a thickness of 2.0 mm and a softening temperature of 85 ° C to form a metal thin film. Further, an acrylic resin paint (trade name "PLUS COAT"# 64-16, manufactured by Toho Kaken Co., Ltd.) was spray-coated on the metal thin film to form a protective film having a thickness of 20 µm.

A plurality of samples of the synthetic resin end plate thus obtained were
Molding tests were carried out by heating to ℃, 100 ℃, 120 ℃, 140 ℃ respectively. This molding test is based on the vacuum molding method, and as shown in FIGS. 1 and 2, the molded product (1) is formed by arranging the square base unit bulges (2) of 150 mm × 150 mm in the form of a base. In the molding, the molding depth (H) was set to 10 mm.

Then, the moldability and the specularity of the surface of the molded product were evaluated, and the results are shown in Table 1. Here, the evaluation of the mirror surface property is shown by the mark ◯ when the surface was not matted after the molding and maintained a good mirror surface, and by the mark x when the haze occurred. In addition, the evaluation of the moldability is indicated by ○ when it was possible to mold with a molding depth of 10 mm or more without cracking the metal thin film, and × when molding with a molding depth of 10 mm was impossible. It is indicated by a mark.

Example 2 As a synthetic resin substrate, a transparent polyvinyl chloride resin plate having a thickness of 3 mm and a softening temperature of 60 ° C. (trade name “Sanroid Uni, G170”)
(Made by Tsutsunaka Plastic Industry Co., Ltd.), except that a synthetic resin end plate is made in the same manner as in Example 1 and the heating temperature is changed to 55 ° C., 70 ° C., 90 ° C., 120 ° C. A molding test was conducted. The results are shown in Table 2.
The molding conditions and the evaluation method other than the heating temperature are the same as in Example 1.

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

[Brief description of drawings]

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

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B29L 31:44

Claims (1)

[Claims] 1. A thermoplastic resin substrate having a metal thin film formed on one surface thereof, and a protective coating made of a thermoplastic resin coating formed on the surface of the thermoplastic resin substrate to prepare a synthetic resin end plate, and the end plate is then attached to the thermoplastic resin substrate. A method for producing a synthetic resin mirror-molded article, which comprises heating to a temperature higher than the softening temperature T ° C of 10 to 35 ° C to perform thermoforming.