JPH0516302A - Laminate prevented from yellowing by ultraviolet ray - Google Patents

Abstract

PURPOSE:To provide a laminate composed of a synthetic resin film in which yellowing by ultraviolet rays is prevented effectively. CONSTITUTION:A laminate is obtained by forming an external layer consisting of a film or a sheet, in which an ultraviolet absorber is blended with polyolefin, on the surface of an internal layer made up of the film or sheet of a thermoplastic resin, with which a pigment is compounded. A layer, with which pearl- essence is mixed, may also be formed as the intermediate layer of the laminate, and pearl-essence may also be blended with the internal layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate which is prevented from yellowing due to ultraviolet rays.
The present invention relates to a laminate which can effectively prevent yellowing due to ultraviolet rays even when a synthetic resin film or sheet is mixed with a pigment.

[0002]

2. Description of the Related Art It is well known in the art to blend an ultraviolet absorber into a plastic molded article, particularly a film or a sheet, for the purpose of preventing yellowing due to these ultraviolet rays. When a white pigment or pearl essence is mixed in the synthetic resin of the material in order to give a pearly luster, the yellowing of the film etc. due to ultraviolet rays can be seen at a glance, so these laminates are In most cases UV absorbers are included.

[0003]

However, when the film or sheet is simultaneously blended with a pigment or another compounding agent and a UV absorber, the UV absorbing ability of the UV absorber tends to decrease. However, there has been a problem that yellowing of a film or the like cannot be avoided even if an ultraviolet absorber is mixed in the film. Therefore, an object of the present invention is to provide a laminate which does not cause yellowing due to ultraviolet rays, even if a pigment and an ultraviolet absorber are simultaneously present in a film or sheet, without lowering the ultraviolet absorbing ability of the ultraviolet absorber. Especially.

[0004]

According to the present invention, a thermoplastic resin film or sheet containing a pigment (hereinafter, simply referred to as a film or the like) on the surface of an inner layer is a film containing a polyolefin containing an ultraviolet absorber. There is provided a laminate having an outer layer formed of a sheet.

In the laminate of the present invention, by providing the pigment mixed with the thermoplastic resin forming the film and the ultraviolet absorber as separate layers, the ultraviolet absorbing effect of the ultraviolet absorber due to the presence of the pigment is reduced. It is possible to prevent the transmission of ultraviolet rays to the inner layer that easily yellows due to the presence of the outer layer containing the ultraviolet absorber, even if the outer layer itself yellows a little, the outer layer itself Since it is a thin layer, yellowing can be made inconspicuous as a whole.

Further, in the present invention, pearl essence may be blended in order to impart a pearly luster to the obtained laminate. In this case, between the inner layer and the outer layer described above, a laminated body in which an intermediate layer in which pearl essence is blended with polyolefin is formed, or by blending pearl essence in the inner layer itself, a pearly tone with a suppressed yellow tint is obtained. It is possible to obtain a laminate having the above gloss.

In the present invention, polypropylene, polyethylene or the like capable of forming a transparent film is preferably used as the polyolefin forming the outer layer. When polyethylene is used, low-density polyethylene having a density of 0.915 to 0.930 g / cm ³ is used, and in the case of polypropylene, MI is 2.5 g / 10 min or more and the weight average molecular weight / number average molecular weight is 3 to 5, preferably 3.5
It is preferred to use a propylene / ethylene copolymer having a molecular weight distribution of from 4.5 to 4.5 and an ethylene content of from 2 to 8% by weight, preferably from 3 to 5% by weight.

As the ultraviolet absorber to be blended in the outer layer, all known ultraviolet absorbers can be used, but in particular, tinuvin, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-. Methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,4-dihydroxybenzophenone,
Resorcinol monobenzoate, 2 (2'-hydroxy-5-methylphenol) benzotriazole, substituted benzotriazole, ethyl-2-cyano-3,3-diphenol acrylate, phenyl salicylate, 4-t-
Butyl phenyl salicylate. p-octylphenyl salicylate, Ni-bisoctylphenyl sulfide,
[2,2'-thiobis (4-t-octylphenolato)]-n-butylamine Hi and the like can be mentioned.

As the thermoplastic synthetic resin forming the inner layer, a film-forming thermoplastic synthetic resin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, nylon,
Although thermoplastic synthetic resins such as polyester can be used,
In order to provide excellent adhesion to the outer layer, it is preferable to use the same resin as that used for the outer layer.

As the pigment to be mixed in the inner layer, titanium pigments such as titanium white and titanium yellow are used, but depending on the required color tone, they may be mixed and used. The pigment is preferably blended in at least 2.0 to 3.0% by weight with respect to the thermoplastic synthetic resin.

When pearl essence is blended in the intermediate layer or the inner layer, either mica-based or titanium-based pearl essence can be used. However, since these pearl essences have poor dispersibility in a synthetic resin, Usually, it is preferable that the aging is carried out for 2 hours or more, and then the mixture is mixed in a ratio of 2 to 3% by weight.

According to the experiments by the present inventors, when 2 to 3% by weight of pearl essence is added to the synthetic resin, the pigment of the inner layer is 0.01 to 0.06% by weight to the synthetic resin. %, Especially 0.02 to 0.04% by weight
It has been found that it is preferable to blend in the above range, whereby a laminate having a light color tone and a deep pearl luster can be obtained without impairing the pearl luster.

In the present invention, when pearl essence is blended with the intermediate layer or the inner layer, the inner layer is opaque due to the presence of the pigment, so that the light pearly gloss when viewed from the outside becomes deeper, and the inner layer further. When the pigment is colored in a desired color tone, the combination of the light pearly luster of the intermediate layer and the color tone of the inner layer is combined, and it is possible to express pearly luster of a variety of color tones.

The synthetic resin composition for forming the outer layer and the inner layer is prepared by mixing the blending components by a method known per se, for example, a ribbon blender, a Henschel mixer, etc., and then melt-mixing with an extruder, Banbury mixer, two rolls, etc. It can be performed by the method of doing.

When the outer layer and the inner layer are laminated, when a thermoplastic synthetic resin in which the inner layer does not easily adhere to the outer layer, for example, nylon which does not easily adhere to the outer layer polyolefin as the inner layer, is used as the adhesive layer, An adhesive synthetic resin layer, for example, a layer of polyethylene graft-modified with unsaturated carboxylic acid or its derivative can be interposed.

The polyethylene, which is the backbone polymer of the modified polyethylene used as the adhesive layer, has a density of 0.
A homopolymer of ethylene produced by a medium or low pressure method of 94 or more, or a copolymer of ethylene and another α-olefin such as propylene, butene-1, pentene-1 is preferably used.

Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid. The unsaturated carboxylic acid derivative includes acid anhydrides, esters, amides, imides, metal salts and the like, such as maleic anhydride, citraconic anhydride, itaconic anhydride, methyl acrylate, methyl methacrylate, acrylic acid. Ethyl, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, maleic acid monoethyl ester, maleic acid diethyl ester, fumaric acid monomethyl ester, fumaric acid dimethyl ester,
Itaconic acid, monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, maleic acid-N
-Monoethylamide, maleic acid-N, N-diethylamide, maleic acid-N-monobutylamide, maleic acid-N, N-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide, Fumaric acid-N, N-diethylamide, fumaric acid-N-monobutylamide, fumaric acid-N, N-dibutylamide, maleimide, N-butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate,
Examples thereof include potassium acrylate and potassium methacrylate. Of these grafting monomers it is most preferred to use maleic anhydride.

The method of grafting an unsaturated carboxylic acid or a derivative thereof to a polyolefin is a method well known in the art, for example, a trunk polymer and a graft monomer are added in the presence or absence of a solvent, or a radical initiator is added or It can be easily performed by a method of heating to a high temperature without adding.

Further, the thickness of each layer of the laminate of the present invention is not limited to this, because it varies depending on the application to be used, but generally the outer layer is about 3 to 15 μm, the inner layer is about 60 to 100 μm, and the outer layer / The thickness ratio of the inner layer is usually preferably in the range of 5 to 15/95 to 85 in order to effectively prevent yellowing. When the pearl essence is provided as the intermediate layer, the intermediate layer is 3 to 15
It is preferably in the range of μm. Further, when the adhesive layer is provided, it is desirable that the thickness thereof is formed as thin as possible, and usually it is formed to be about 1 to 5 μm.

[0020]

【Example】

Example 1, Comparative Examples 1 and 2 Three types of films having the configurations shown in Table 1 (R is a comparative example,
(E indicates an embodiment), a fluorescent lamp (1200LUX)
For 200 hours, the film turns yellow according to JISK 71
03. The films R1 and R2
Is a single layer having a thickness of 0.8 mm, and the film E1 is
The inner / outer layer ratio is 20: 1, and the total thickness is 0.8 mm like the films R1 and R2. The results are also shown in Table 1.

[0021]

Example 2, Comparative Example 3 Two kinds of films R3 and E2 having the constitutions shown in Table 2 were irradiated with a fluorescent lamp (1200 LUX) for 200 hours, and yellowing of the films was measured according to JIS K7103. The film R3 has an inner / outer layer ratio of 10: 1,
The total thickness is 0.9 mm, and the film E3 has an inner layer, an intermediate layer,
The ratio of the outer layers is 10: 1: 0.5 and the layer thickness is 0.9 mm, similar to R3. The results are also shown in Table 2.

[0023]

Comparative Example 4 A UV absorber (Tinuvin) was added to the outer layer of the film of Comparative Example 3.
A film R4 added with 500 ppm was prepared, irradiated with a fluorescent lamp in the same manner as in the above-mentioned example, and then yellowing of the film was measured. The results are shown in Table 3.

[0025]

Example 3 In the structure of the film of Example 2, the effect on yellowing was measured by changing the ratio of the thickness of the outermost layer to the thickness of the entire laminate. The results are shown in Fig. 1. In addition, the measurement was performed using a fluorescent lamp (1
200 LUX) for 200 hours.

[0027]

INDUSTRIAL APPLICABILITY According to the present invention, a laminate is formed by forming an outer layer made of a film or sheet made by blending polyolefin with an ultraviolet absorber on the surface of an inner layer made of a thermoplastic resin film or sheet blended with a pigment. Even when the pigment and the ultraviolet absorber are simultaneously blended with the above, it is possible to provide a laminate which does not deteriorate the ultraviolet absorbing ability of the ultraviolet absorber and does not yellow due to ultraviolet rays. Further, by mixing pearl essence in the intermediate layer or the inner layer, it is possible to provide a laminate having a pearly luster that suppresses the yellow tint.

[Brief description of drawings]

FIG. 1 is a graph showing the influence of the outer layer thickness on the degree of yellowing in a laminate of Example 2 of the present invention.

Claims (4)

[Claims] 1. A laminate comprising an inner layer formed of a thermoplastic resin film or sheet containing a pigment, and an outer layer formed of a film or sheet obtained by mixing a polyolefin with an ultraviolet absorber on the surface of the inner layer. 2. The laminate according to claim 1, wherein an intermediate layer in which pearl essence is mixed with polyolefin is formed between the inner layer and the outer layer. 3. The laminate according to claim 1, wherein the inner layer contains pearl essence. 4. The outer layer is based on the total thickness of the laminate.
The laminate according to claim 1, having a thickness of 0.05 to 0.15.