JPS62151427A - Elimination of stress-whitened part of resin - Google Patents

Abstract

PURPOSE:To rapidly eliminate stress-whitened parts without giving bad influence to a resin, by exposing the stress-whitened parts of vinyl chloride resin to an atmosphere at a respective specific temperature and a specific relative humidity. CONSTITUTION:Stress-whitened parts of vinyl chloride resin are exposed to an atmosphere at a temperature 10 deg.C lower than the softening point of the vinyl chloride resin and at 80-100% relative humidity and eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention eliminates the stress whitening of the resin caused by pressing of metal/resin composite plates, etc., and reveals the original appearance of the resin. This relates to the method of extinguishing parts.

[Prior Art] Conventionally, metal/resin composite plates have been used for various purposes for the purpose of reducing weight. Depending on the purpose, it is used not only as a plate but also processed into various shapes.

[Problems to be Solved by the Invention] One of the above-mentioned processes is cold pressing, but
When processed at room temperature in this manner, the bent portions of the resin, etc., cause so-called stress whitening phenomenon.

This phenomenon impairs the aesthetic appearance of the metal/resin composite board, and is therefore extremely inconvenient when used for exterior panels.

To prevent this, there is a method of molding using a press heated to near the softening point of the resin, but this leads to poor adhesion and color unevenness due to a decrease in the strength of the adhesive between the resin and metal, resulting in a decrease in yield. .

There are also methods of heating the whitened area to near its softening point after cold pressing, and methods of exposing the resin to solvent vapor, but these methods take time to eliminate the whitened area and affect the surface properties of the resin and its adhesion. If a solvent such as toluene, acetone, or ethyl acetate is used, it may cause deformation or deterioration of the fat, and may cause problems in terms of pollution control, safety and health, etc. It also required specific space and equipment.

The present invention has been made with the aim of solving the above-mentioned problems and realizing a method of quickly eliminating the whitened portion without adversely affecting the resin.

Means for Solving Problem L] That is, the present invention provides a method for eliminating stress-whitened portions of a resin, in which the stress-whitened portions of a vinyl chloride resin are eliminated by heating the stress-whitened portions, including the softening of the vinyl chloride resin. The gist of the present invention is a method for extinguishing the stress whitening portion of a resin, which is characterized in that the stress whitening portion is removed at a temperature 10° C. lower than the point above the point and in an atmosphere with a relative humidity of 80 to 100%.

Here, the vinyl chloride resin refers to a comonomer of vinyl chloride polymer such as vinyl acetate, vinylidene chloride, acrylic ester, methacrylic ester, acrylonitrile, ethylene, propylene, etc. and vinyl chloride.

The heating needs to be at a temperature that is 10° C. lower than the softening point of the resin.

The water vapor needs to have a relative humidity of 80 to 100% in order to eliminate the whitened areas.

[Effect] Although the effect of the present invention is not clear, whitening is caused by molecular alignment in a certain direction due to plastic working. In that state, it appears white due to the refraction of light. This (-) is understood to be caused by the action of water molecules along with heat, causing them to be quickly arranged in random directions.

[Example] A laminate of hard vinyl chloride (softening point: 85°C, thickness: 100 μm) and aluminum (product number: A1100-0, thickness: 250 μm) was cold pressed into a cylindrical shape (diameter: 33 mm x
depth 20mm) or square tube shape (150mm x 150mm
A convex portion with a depth of 20 mm) was formed. This processing resulted in stress whitening in the hard vinyl chloride layer near the corners.

The above molded product is heated in an atmosphere with various water vapor pressures.

Then, the state of disappearance of the whitening near the corner was observed.

The results are shown in Table 1.

As shown in Table 1, above 75℃ and relative 1 degree 8
It can be seen that the whitened areas are eliminated very well and quickly in the range of 0 to 100%. It turns out that there is no comparison.

When the method of this example was applied to other vinyl chloride resins, similarly good results were obtained.

[Effects of the Invention] In the present invention, since water vapor at a relative humidity of 80 to 100% is applied to the whitened portion at the same time as heating at a temperature 10°C lower than the resin softening point, the resin and its adhesion are Whitened areas can be quickly eliminated at a high yield without adversely affecting the product.

Therefore, it is possible to efficiently produce processed products with excellent surface properties by using a cold press with high production efficiency.

Claims (1)

[Claims] A method for erasing the stress whitening part of a vinyl chloride resin by heating the stress whitening part, the method comprising: heating the stress whitening part of the vinyl chloride resin to eliminate the stress whitening part; , and a method for eliminating stress-whitened parts of a resin, which comprises exposing the stress-whitened parts to an atmosphere with a relative humidity of 80 to 100%.