JPS591581B2 - Method for manufacturing foam sheet with uneven pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a foam sheet having an uneven pattern.

Conventional methods for manufacturing foam sheets with uneven patterns include Renkai Publication No. 52-128964 and Japanese Patent Publication No. 54-28.
Reactive plasticizers, as disclosed in Publication No. 865;
A portion of a foamable vinyl chloride resin sheet containing a foaming agent and a photosensitizer, printed with a paint that has an ultraviolet shielding effect in an arbitrary pattern on the surface, heated and foamed after irradiation with ultraviolet rays, and printed with a paint that has an ultraviolet shielding effect. There is a known method of obtaining a foam sheet having an uneven pattern by expanding the foam and not foaming the areas where the paint having an ultraviolet shielding effect is not printed.

However, with these methods, it is not possible to color the concave portions of a foam sheet having an uneven pattern with a paint having a strong ultraviolet shielding effect, and it is not possible to obtain a foam sheet having an uneven pattern with a desired color scheme. Ta.

In other words, when coloring the concave portions of a foamable vinyl chloride resin sheet, it can only be colored with a color that allows sufficient ultraviolet rays to pass through, and there are major restrictions on the pigments used in the paint. If white or black is required to color the recesses, titanium oxide or carbon black, which has a strong ultraviolet shielding effect, must be used as a pigment, making it impossible to form an uneven pattern. It was hot. In addition, according to these conventional methods, decomposition of the blowing agent in the concave portions of the foam sheet having an uneven pattern is suppressed by crosslinking of vinyl chloride, resulting in abnormal foaming and generation of air bubbles on the surface of the concave portions. There was a problem. Therefore, as disclosed in Japanese Patent Publication No. 54-9549, a method of applying a paint with a strong ultraviolet shielding effect to the recesses is to use a reactive plasticizer, a foaming agent, and a photosensitizer. A paint having an ultraviolet shielding effect is printed in a pattern on the surface of the foamable vinyl chloride resin sheet, which is then irradiated with ultraviolet 0 rays, and then the areas where the paint having an ultraviolet shielding effect is not applied, A method has been proposed in which a separate paint is printed and then heated and foamed.

However, in this improved method, the process of ultraviolet irradiation must be interrupted and printing must be performed twice, and two or more printing machines must be prepared, which is not only uneconomical but also requires the recessed portions to be printed. There was also no improvement in the problem that abnormal foaming occurred and bubbles were generated on the surface of the recessed portion.

The present invention improves the drawbacks of the conventional method described above, eliminates restrictions on the paint that can be applied to the areas of the expandable vinyl chloride resin sheet where the recesses are to be formed, and solves the problem of bubble generation due to abnormal foaming of the recesses. It is an object of the present invention to provide a method for manufacturing a foam sheet having an uneven pattern.

That is, the method for producing a foamed sheet having an uneven pattern according to the present invention involves partially applying coating material A having an ultraviolet shielding effect to the surface of a foamable vinyl chloride resin sheet containing a reactive plasticizer, a foaming agent, and a photosensitizer. In addition to printing in a pattern, paint B having the same or different ultraviolet shielding effect as paint A is applied to the areas where paint A is not printed, at an aperture ratio (paint B
Printing so that the unprinted area/area of the part where paint A is not printed is 0.30 to 0.95, and the printed areas and non-printed areas of paint B are alternately present, This consists of irradiating it with ultraviolet rays and then heating and foaming it.

As the reactive plasticizer that can be used in the present invention, any reactive plasticizer that is generally used as a reactive plasticizer for vinyl chloride resins may be used, and specific examples include the following.

An ester compound having 12 or more ethylenically unsaturated bonds.

(1) Acrylic acid, chloroacrylic acid, alkoxyacrylic acid, alkyl acrylic acid, allyl acrylic acid, a,
α,β-unsaturated monocarboxylic acids such as silaacrylic acid and ethylene glycol, propylene glycol, n-butene glycol, IsO-butylene glycol, 1,3-butylene glycol, 1,5-benzenediol, diethylene glycol, trimethylolpropane , glycerin, aliphatic polyhydric alcohol such as bentaerythritol.

For example, ethylene glycol dimethacrylate, 1,3-
Monomers or low molecular weight polyesters such as butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate. (2) Esters of aliphatic unsaturated dicarboxylic acids such as maleic acid and iconic acid, or benzene di- or tricarboxylic acids such as phthalic acid and trimellitic acid, and allyl alcohol.

For example, monomers or prepolymers such as diallyl itaconate and diallyl phthalate. (3) Phosphoric acid esters such as diallylbutyl phosphate, diallyloctyl phosphate, etc.

(4) Unsaturated polyester resin prepolymer. Acrylic modified epoxy resin, acrylic modified polyester resin, acrylic modified polyurethane resin, etc. The above reactive plasticizers may be used alone or in combination.

From the viewpoint of unevenness effect, it is preferable to use a compound having three or more ethylenically unsaturated bonds. Examples of the blowing agent used in the present invention include azo compounds such as diazoaminobenzene and azodicarbonamide, hydrazide compounds such as benzenesulfonyl hydrazide, and nitro compounds such as N,NI-dinitrosopentamethylenetetramine. In view of temperature and other factors, V1, especially a blowing agent containing azodicarbonamide as a main component, is preferred.

As the photosensitizer, any compound can be used as long as it generates polymerizable radicals upon irradiation with ultraviolet rays.

For example, benzoin compounds such as benzoin, benzoin ethyl ether, and benzoin isobutyl ether, benzophenone compounds such as benzophenone, polychloride compounds such as hexachloroethane, sulfide compounds such as diphenyl disulfide, and quinone compounds such as quinone. etc. The vinyl chloride resin used in the present invention may be a homopolymer of vinyl chloride, or may be a homopolymer of vinyl chloride and vinyl acetate.
It may be a copolymer with ethylene, propylene, acrylic ester, methacrylic ester, etc., or it may be a blend of vinyl chloride resin and other resin. There are no restrictions on the plasticizers, stabilizers, etc. added to the vinyl chloride resin, and all plasticizers and stabilizers commonly used for vinyl chloride resins can be used.

However, when azodicarbonamide is used as a blowing agent, it is necessary to add what is generally called a blowing aid, such as a Pb-based compound, a Zn-based compound, a Cd-based compound, or urea. Paints that have a UV-shielding effect include vinyl chloride-based paints, acrylic paints, urethane-based paints, etc. that are generally used as paints for vinyl chloride resin, as well as UV absorbers, organic fluorescent pigments, and pigments that shield UV rays. These can be used singly or in combination.

The portions of the foamable vinyl chloride resin sheet containing a reactive plasticizer, blowing agent, and photosensitizer are printed with the above-mentioned paint having an ultraviolet shielding effect on the entire surface where the convex portions are to be formed, and the above-mentioned paint is printed on the portions where the concave portions are to be formed. The paint has an ultraviolet shielding effect and has an aperture ratio of 0.3.
0 to 0.95, and must be printed so that printed and non-printed areas alternate.

The aperture ratio of 0.30 to 0.95 means Y/X: 0530 to 0.95, as shown in Figure b. The purpose of the present invention cannot be achieved simply by printing with an aperture ratio of 0.30 to 0.95, and printed areas and non-printed areas alternate in the form of scattered dots, stripes, grids, etc. You must do so. In the case of scattered dots, the number of meshes is preferably 20 or more, particularly preferably 40 or more. In the case of a striped or lattice pattern, the line width of the printed portion is preferably 0.05 to 0.5. It is preferable that the width of the printing part is not too large, and is preferably 0.5 to 0.5 or less.
When the aperture ratio is 0.30 or less, substantially no recesses will be formed when the expandable vinyl chloride resin sheet is foamed.
Further, when the aperture ratio is 0.95 or more, it is the same as that obtained by conventional methods, and the aperture ratio must be 0.30 to 0.95, preferably 0.50 to 0.80.
To form a printed layer of paint A and a printed layer of paint B on the surface of a foamable vinyl chloride resin sheet containing reactive plasticity, a blowing agent, and a photosensitizer, the following three methods and their mixing methods are used. Can be adopted.

1 Either the print layer of paint A or the print layer of paint B is formed first, and then the remaining print layers are formed.

2. Form a printed layer of paint A and a printed layer of paint B at the same time.

3. A printed layer of paint B is formed on the entire surface, and then a printed layer of paint A is partially overlapped and formed.

According to the method of the present invention, the surface of a foamable vinyl chloride resin sheet containing a reactive plasticizer, a blowing agent, and a photosensitizer is printed with a pattern of paint A having an ultraviolet shielding effect, and the paint A is applied. A paint having the same or different ultraviolet shielding effect as the paint A is applied to the unprotected areas with an aperture ratio of 0.30.
~0.95, and there are printed and non-printed areas alternately, so when this is heated and foamed after being irradiated with ultraviolet rays, the area where paint A was applied will expand and form convexities. , the area to which paint B was applied also foamed and expanded, but the degree of expansion was extremely small compared to the area to which paint A was applied, and the area to which paint A was not applied essentially formed a depression. do.

Moreover, in this concave part, the part where paint B is applied expands into small protrusions, and since paint B is printed on the top of the small protrusions, the concave part appears to be colored with the color of paint B. Has an appearance. In other words, a foamed sheet having an appearance in which the recesses are also colored in an arbitrary color can be obtained. Furthermore, since the portion of paint B expanded and expanded in the form of small protrusions, no bubbles were generated in the recesses due to abnormal foaming, which was preferable. Examples are given below to explain the present invention in more detail, but the present invention is not limited to these Examples. Example: A foamable vinyl chloride composition having the following formulation was placed on paper 1.
．． The resin was coated to a thickness of 2 to 30° C. and heated for 1 minute at a temperature of 180° C. to obtain a foamable vinyl chloride resin sheet 2 using the paper 1 as a base material.

On the surface of the obtained expandable vinyl chloride resin sheet 2, a paint having an ultraviolet shielding effect of the following composition is partially printed in a pattern to form a first printed layer 3, and then the paint is printed. Apply the same paint as the above paint to the areas where the paint is not present, with an open area ratio of 70%.
The second printed layer 4 was formed by printing in a scattered dot pattern (50 meshes).

A high-pressure mercury lamp (80 W/C
! TL) When the foamable vinyl chloride resin sheet was foamed by irradiating ultraviolet rays at a speed of 8 m/min with 3 lamps and then heating at 21°C for 1 minute and 30 seconds, the 3 parts of the first printed layer were Although the foam expanded significantly, the second printed layer 4 was foamed only in the form of small protrusions, resulting in a foamed sheet 5 having an uneven pattern. The convex portions of this foamed sheet were white, V1 and the concave portions also had a white appearance, and no air bubbles due to abnormal foaming were observed in the concave portions. The simple explanatory diagram on page 4 is an explanatory diagram showing the steps of the method of the present invention.

DESCRIPTION OF SYMBOLS 1... Paper material, 2... Expandable vinyl chloride resin sheet, 3... First printing layer, 4...
・Second printing layer, ]...A foamed sheet having an uneven pattern.

Claims (1)

[Claims] 1 Paint A having an ultraviolet shielding effect is partially printed in a pattern on the surface of a foamable vinyl chloride resin sheet containing a reactive plasticizer, a blowing agent, and a photosensitizer, and the paint A is not printed. Paint B having the same or different ultraviolet shielding effect as the paint A is applied to the area with an aperture ratio (area where paint B is not printed/area where paint A is not printed) of 0.30 to 0. 95, and a method for producing a foam sheet having an uneven pattern, characterized in that printing is performed so that printed areas and non-printed areas of paint B are alternately present, irradiated with ultraviolet rays, and then heated and foamed. .