JPS605456B2 - Foam with multi-stage uneven pattern - Google Patents

Description

[Detailed description of the invention] The present invention relates to a foam having a multi-stage uneven pattern.

BACKGROUND ART A method for producing a foam having an uneven pattern using a crosslinking reaction caused by ultraviolet irradiation has been known.

This method is described, for example, in Japanese Patent Publication No. 54-28865, in which the surface of a foamable synthetic resin sheet A containing a reactive plasticizer, a foaming agent, and a photosensitizer that can be crosslinked and polymerized and cured by ultraviolet rays is used. After UV irradiation (Fig. 1 a, b), heat foaming (first stage) is carried out.
Figure c) is characterized by dividing the foamable sheet A into an ultraviolet irradiated area and a non-irradiated area A'', causing polymerization and curing by crosslinking only in the irradiated area, hardening the resin, The uneven pattern was formed without foaming.

Although this method is good for obtaining an uneven pattern, it cannot meet the demand for a multi-stage uneven pattern.

One method for obtaining a foam having a multi-stage uneven pattern is to apply two or more types of printed patterns with different ultraviolet shielding effects on the surface of the foamable synthetic resin sheet, thereby changing the ultraviolet absorbance of the reactive plasticizer. A method has been proposed in which the height of the foamed portion is varied by creating a difference in the degree of crosslinking of reactive plasticizers (Japanese Unexamined Patent Publication No. 128964/1982).

However, since the crosslinking reaction is a chain reaction caused by radicals, it is very difficult to stop the reaction in an arbitrary state, and the crosslinking is likely to be completed by absorption of a small amount of ultraviolet light. In other words, since the degree of crosslinking is no longer proportional to the number of photons of absorbed ultraviolet light, it is virtually impossible to create a multi-level uneven pattern on the foam surface due to the difference in ultraviolet absorbance, that is, the ultraviolet shielding effect of the printed pattern. It was hot. The present invention aims to provide a foam having a multi-stage uneven pattern that could not be achieved with the above-mentioned prior art, and will be described below based on embodiments shown in the accompanying drawings.

The present inventors discovered that, in the prior art shown in FIG. Since it is connected to the cured ultraviolet irradiated area A' and a slight crosslinking reaction may occur due to the slight amount of ultraviolet rays refracted by the ultraviolet irradiated area A', the area near the boundary of the non-UV irradiated area A'' Now, we assume that there is a slight foaming inhibition effect, and if we reduce the width of the foaming section so that the foaming inhibition effect occurs over the entire width of the foaming section, we can adjust the height of the foaming section and create a multi-stage structure. It was discovered that a foam having an uneven pattern can be produced, and based on this knowledge, an attempt was made to create a multi-stage uneven pattern as follows. FIG. 2 is a conceptual diagram showing the manufacturing process of a foam having a multi-stage uneven pattern according to the present invention;
is a foamable synthetic resin sheet obtained by applying a synthetic resin compound containing an ultraviolet crosslinkable substance, a photosensitizer, and a foaming agent onto a heat-resistant base material 2, and then heating and gelling it; 3 is an ultraviolet shielding ink printed on the foamable synthetic resin sheet 1 at appropriate intervals and having different widths. The resin used in the synthetic resin compound is preferably a thermoplastic resin such as vinyl chloride resin.
In addition, as a method for applying the synthetic resin compound onto the base material, it is best to use commonly used methods such as the calendar method, doctor knife coater method, and reverse roll coater method. A smooth finish is desirable. It is also possible to add commonly used pigments and dyes to the synthetic resin compound to color the foamable synthetic resin sheet, and the pigments and dyes can be used alone or in a mixture of two or more types. The amount of pigment or dye added is preferably 5 parts by weight or less in order to transmit ultraviolet rays.

Base materials include woven fabrics, knitted fabrics, non-woven fabrics, paper, wooden boards, metal plates, glass plates, glass wool, plastic plates, plastic films, asbestos cloth, etc., as well as materials impregnated or coated with synthetic resins. You can also use

In addition to regular paper materials, it is also possible to use hina-katagami paper, and if a releasable base material such as hina-katagami paper is used, it is necessary to peel off the releasable base material at the end. In this case, it is possible to obtain a foamed sheet having an uneven pattern without diamonds on the base material. In addition to resins, substances capable of crosslinking with ultraviolet light include oligomers and monomers, and resins may be used alone or in combination of two or more resins, and the same applies to oligomers and monomers.

It is also possible to use a combination of a resin and a monomer. Examples of UV-crosslinkable resins used in the present invention include epoxy resins containing two or more epoxy groups in one molecule, such as bisphenol A-type epoxy resins, phenol volac-type epoxy resins, and cresol novolac-type epoxy resins; Epoxy acrylate resin, which is a reaction product with a basic acid; spiran resin, which is a reaction product of a polyvalent cycloacetal compound and a glycol unsaturated monocarboxylic acid monoester or a polyhydric alcohol unsaturated monocarboxylic acid ester monool; In addition to lylfretalate resin, various acrylic modified resins and methacrylic modified resins can be mentioned.

Moreover, oligoester acrylate can be used as the ultraviolet crosslinkable oligomer.

Examples of monomers that can be crosslinked with ultraviolet light include ethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate,
Ester of polyhydric alcohol and acrylic acid such as diventaerythritol bentaacrylate, polyhydric alcohol and methacrylic acid such as ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, tetramethylolmethanetetramethacrylate, diventaerythritol bentamethacrylate In addition to these esters, there are diallyl phthalate, triallylysocyanurate, tris(2-methacryloyl, oxyethyl)isocyanurate, and the like.

Examples of photosensitizers include commonly used photosensitizers such as benzoin alkyl ethers such as benzoin methyl fable, benzoin ethyl ether, benzoin-n-butyl ether, and benzoin isobutyl ether, penzophenone, and 5-nitrosoacenaphthene. One type of sensitizing agent or a combination of two or more types can be used.

In addition, a catalyst such as a tertiary amine or a metal compound can also be used together with the photosensitizer. As the blowing agent, commonly used ones such as azodicarbonamide, P,P'-oxybisbenzenesulfonylhydraside, P-toluenesulfonylhydrazide, dinitrosobentamethylenetetramiso, etc. can be used. As ultraviolet shielding ink, one or more of the following ultraviolet shielding agents and/or ultraviolet absorbers are added to commonly used organic solvent-based, water-based, or solvent-free inks. In order to obtain a usable and good uneven pattern, the concentration of the ultraviolet shielding agent and/or ultraviolet absorber in the ink is preferably 1 to 75% by weight, and the ultraviolet transmittance of the printed layer is preferably 20% or less.

The ultraviolet transmittance referred to here is measured using a spectrophotometer MPS using a 0.08 m/m thick colorless transparent polyester film printed with ink using gravure printing and then dried.
-5000 (manufactured by Shimadzu Corporation), refers to the ultraviolet transmittance in the wavelength range of 365 m. If the concentration of the UV blocking agent and/or UV absorbing agent is less than 1% by weight, or if the UV transmittance of the printed layer exceeds 20%, the UV blocking effect will be insufficient and the foam cells in the convex portions will become rough. A good uneven pattern cannot be obtained, and if the concentration of the ultraviolet shielding agent and/or ultraviolet absorber exceeds 75% by weight, the printability and strength of the printed layer will deteriorate. The ultraviolet shielding agents used in the present invention include carbon black, yellow lead, cadmium yellow, red red, cadmium red, lake red, ultramarine blue, phthalocyanine flu, phthalocyanine green, titanium oxide, antimony trioxide, and other commonly used inorganic or In addition to organic pigments or dyes, calcium carbonate, talc,
Clay, silica, metal powder, etc. can also be used. In addition, as ultraviolet absorbers, pt-butylphenyl salicylate, 2
, 4-dihydroxybenzophenone, 2-hydroxy 4-toxybenzophenone, 2-hydroxy 4-penzyloxybenzophenone, 2-hydroxy 4-n octoxybenzophenone, 2-(2' -Hydroxy 4-n octoxyphenyl)-benzotriazole, 2-(3',5'-alkyl-2-hydroxyphenyl)-benzotriazole, 2-(hydroxy-
5-tbutylphenyl)-penzotriazole, 2-(
3,5-di-t-butyl-2-hydroxyphenyl)-benzotriazole, which is commonly used, can be used. As a method for applying the ink, gravure printing, printing using an intaglio roll, transfer printing, various screen printing, spray painting, etc. can be used.

The amount of the ultraviolet crosslinkable substance added is preferably 5 to 10 parts by weight per 100 parts by weight of the synthetic resin, and the amount of the blowing agent added is preferably 1 to 1 part by weight.

In addition, the amount of photosensitizer added is 1 to 1 of the amount of the ultraviolet crosslinkable substance.
It is preferably 20%, and one or more photosensitizers and one or more catalysts may be used in combination.

Note that the catalyst concentration in this case is preferably 0.01 to 1%. The foamable synthetic resin sheet 1 having the above-mentioned composition and printed with the ultraviolet shielding ink 3 consisting of a plurality of lines having different widths is irradiated with ultraviolet rays (Fig. 2a), and then heated and foamed (Fig. 2). b) When the width of the line exceeds 1.5, the height of the foamed part remains constant regardless of the thickness of the line, and if the width of the line is 1.5 or less, The height of the foamed portion increased almost proportionally. In addition, we examined the points in the same way, and found that if the area of the points exceeds 3 sides, the foaming part will not become multi-stage, but if the area decreases from 3 sides, the degree of foaming will decrease accordingly. I saw it and put it out. A preferred embodiment is shown below.

EXAMPLE A synthetic resin compound having the composition shown in Table 1 was applied to the surface of paper on the 0.1 thickness side and heated at 150° C. for 2 minutes to obtain a foamable vinyl chloride sheet.

An ink having an ultraviolet transmittance of 3.6% was applied to the surface of the sheet as dots having the area or lines having the width shown in Table 2, and after drying, the ink was applied with an 80W condensing high pressure mercury lamp for 80 minutes.
The sample was irradiated with ultraviolet light on the m/side and further heated for 2 minutes at 200 oo. Table 2 shows the thickness of the sheet after foaming. table ]
- Table 2 As is clear from the above examples, the thickness of the foamed part increases as the area or width increases, in the case of a point, the area is 3 skins 2 or less, and in the case of a line, the width is 1.5 or less Therefore, the height of the foamed portion can be arbitrarily adjusted by adjusting the area or width of the plurality of points or lines, and it becomes possible to easily and reliably produce a foamed body having a multi-stage uneven pattern.

Further, as shown in FIG. 3, if the width of one line to be printed is not constant but tapered, a foam having an inclination can be obtained.

In addition to the above, various modifications are possible, such as printing ink on the concave portions of the uneven pattern after irradiation with ultraviolet rays, or printing light-colored ink that does not have an ultraviolet shielding effect on the concave portions before irradiating ultraviolet rays to color the concave portions.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the manufacturing process of a foam having an uneven pattern using an ink having an ultraviolet shielding effect, and Fig. 2 is a conceptual diagram of the manufacturing process of an example of a foam having a multi-stage uneven pattern according to the present invention. FIG. 3 is a perspective view showing another embodiment. 1... Foamable synthetic resin sheet, 2... Base material, 3...
・Ultraviolet shielding ink. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Printing an ink having an ultraviolet shielding effect on the surface of a foamed synthetic resin sheet containing an ultraviolet crosslinkable substance, a photosensitizer, and a foaming agent, irradiating it with ultraviolet rays, and then heating and foaming the foam, in which the ink is printed. The width of the part is 1.
A foam having a multi-step uneven pattern characterized by including lines with a diameter of 5 mm or less and/or points with an area of 3 mm^2 or less.