JP2000336201A - Luminescent polyolefin foam and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foam useful for toys and advertisement items which emits light in a dark place by mixing a luminescent pigment with a polyolefin resin. SOLUTION: A blowing agent, a crosslinking agent and a luminescent pigment are mixed with a polyolefin resin, heated and expanded to obtain a luminescent foam. A blowing assistant is used as necessary. The luminescent pigment preferably contains phosphorescent zinc sulfide (ZnS:Cu) as a main component. When dinitrosopentamethylenetetramine is used as a blowing agent, a luminescent foam with significant luminescence in a dark place can be obtained. When azodicarbonamide is used, a foam with low luminance can be obtained. When a highly transparent ethylene-vinyl acetate copolymer is used as the polyolefin resin, a luminescent foam with significant luminescence in a dark place can be obtained. The luminescent pigment is desirably added in an amount of 2-20 pts. wt. based on 100 pts.wt. of the polyolefin resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphorescent polyolefin foam used for toys, catalogs and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Polyolefin foams are excellent in heat insulation, weather resistance, elasticity, etc., and are used for heat insulation, jointing materials for civil engineering, toys,
It is used for packaging materials, sporting goods, etc. As a method for coloring the polyolefin foam, a method in which a pigment and an organic foaming agent are kneaded with a polyolefin resin and heated and foamed in a long length, or pressure one-stage foaming or two-stage foaming (Japanese Patent Publication No. 2-426)
In this method, the color can be identified in a bright place, but the presence and color of the foam cannot be identified in a dark place.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a luminous polyolefin foam which forms a color in a dark place and is useful for toys, advertising articles and the like, and a method for producing the same.

[0004]

According to the phosphorescent polyolefin foam of the present invention, in order to achieve the above object, a phosphorescent pigment is mixed with a polyolefin resin. According to the method for producing a luminous polyolefin foam of the present invention, a foaming agent, a crosslinking agent, and a luminous pigment are mixed with a polyolefin resin, followed by heating and foaming. The foaming agent used in the present invention is not particularly limited as long as it generates a gas containing nitrogen as a main component by heating to a decomposition temperature, but when dinitrosopentamethylenetetramine is used, color development in a dark place is achieved. Notable. The luminous pigment used in the present invention is a pigment having a property of absorbing and accumulating light such as the sun or a fluorescent lamp, and gradually releasing and emitting the light in a dark place. However, as long as the substance is a repeating substance, it is not particularly limited, but the phosphorescent zinc sulfide (Zn
A substance containing (S: Cu) as a main component is preferable in terms of compatibility with a resin, coloring in a dark place, safety, and heat resistance. In the present invention, it is preferable to add 2 to 20 parts by weight of such a luminous pigment to 100 parts by weight of the polyolefin resin. When the amount of the luminous pigment is less than 2 parts by weight, the coloring phenomenon is weak, and when it exceeds 20 parts by weight, the foaming is adversely affected.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the method for producing a luminous polyolefin foam according to the present invention will be specifically described below. (Pressurized single-stage foaming) Polyphosphorescent pigment, foaming agent,
A foaming aid, a cross-linking agent and, if necessary, a filler are blended and mixed with a heated mixing roll, a pressure kneader, an extruder or the like. The mixture is filled in a mold, and the mold is sealed under pressure, and is heated at 120 to 180 ° C, preferably 130 to 170 ° C for 10 to 50 minutes, preferably 25 to 180 ° C.
Heat for 40 minutes to decompose the foaming agent and cross-linking agent, and after decompression,
Remove the foam. (Two-stage foaming method) Alternatively, a mold is filled with the foamable composition, and the mold is sealed under pressure.
30 to 170 ° C for 10 to 50 minutes, preferably 25 to 4
Heat for 0 minutes to partially decompose the foaming agent and cross-linking agent, depressurize and remove the intermediate foam from the mold. Then, place the intermediate foam into a non-sealed mold corresponding to the shape and dimensions of the final product. Put the body, heat it through the heating medium through the jacket provided in the mold, 140 ~ 200 ℃, preferably 150 ~ 17
By heating at 0 ° C. for 10 to 60 minutes, preferably 20 to 40 minutes, the remaining foaming agent is decomposed and foamed, and a low-density foam having uniform physical properties is obtained.

The polyolefin used in the present invention includes, for example, polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene and vinyl acetate, or ethylene and vinyl acetate, which are usually produced by high, medium and low pressure methods. Copolymer of ethylene and methyl, ethyl, propyl, butyl with each acrylate content of up to 45%, or chlorinated to each of them (chlorine content 60% by weight), or a mixture of two or more of these These are mixtures of these with polypropylene having an isotactic or atactic structure. The ethylene-vinyl acetate copolymer has high transparency of the resin and remarkable color development in a dark place.

[0007] The blowing agent which can be used in the present invention is a chemical blowing agent having a decomposition temperature higher than the melting temperature of the polyethylene resin, such as azodicarbonamide, an azo compound.
Barium azodicarboxylate and the like: nitroso compounds such as dinitrosopentamethylenetetramine and trinitrotrimethyltriamine; hydrazide compounds such as p,
p'-oxybisbenzenesulfonyl hydrazide and the like;
There are sulfonyl semicarbazide compounds such as p, p'-oxybisbenzenesulfonyl semicarbazide and toluenesulfonyl semicarbazide, but when dinitrosopentamethylenetetramine is used, the color is remarkable and azodicarbonamide is used. Then, the brightness is low.
In the present invention, the cross-linking agent is a resin having a decomposition temperature at least equal to the flow start temperature of the resin, is decomposed by heating, generates free radicals, and generates cross-links between or within the molecules. Organic peroxides which are radical generators, such as dicumyl peroxide, 1,1-ditert-butylperoxy-3,3,5-trimethylcyclohexane, 2,5
-Dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexyne, α, α-di-tert-butylperoxyisopropylbenzene, tert-butylperoxyketone And tertiary butyl peroxybenzoate. The most suitable organic peroxide must be selected depending on the resin used at that time.

In the present invention, a foaming aid can be added according to the type of the foaming agent. Examples of the foaming aid include compounds mainly containing urea, metal oxides such as zinc oxide and lead oxide, compounds mainly containing salicylic acid, stearic acid and the like, that is, higher fatty acids and metal compounds of higher fatty acids. In the present invention, for the purpose of improving the physical properties or reducing the price of the composition to be used, a compounding agent (filler) that does not significantly affect cross-linking, for example, zinc oxide, titanium oxide, calcium oxide, magnesium oxide,
Metal oxides such as silicon oxide, carbonates such as magnesium carbonate and calcium carbonate, or fibrous materials such as pulp, or various dyes, pigments and fluorescent materials, and other conventional rubber compounding agents may be added as necessary. it can.

[0009]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples. Example 1 Ethylene vinyl acetate copolymer (trade name “Novatech E
VA LV-440 ", vinyl acetate content 15%, MF
R2.0g / 10min, manufactured by Nippon Polychem Co., Ltd.) 100
Parts by weight, phosphorescent pigment (trade name “GSS”, main component Zn)
S: Cu, particle size 21 μm, specific gravity 4.1, Nemoto Special Chemical Co., Ltd.) 10 parts by weight, dinitrosopentamethylenetetramine 4.0 parts by weight, urea foaming aid 4.0 parts by weight, dicumyl peroxide 0.1 part by weight. 85 parts of a 7 part by weight composition
Kneading with a mixing roll at 155 ° C., filling the above kneaded material in a mold (195 × 380 × 28 mm) in a press heated to 155 ° C., heating under pressure for 35 minutes, and then depressurizing.
A foam was obtained. The obtained foam had an apparent density of 0.06.
g / cm 3, the color developed to pale yellow under sunlight or fluorescent light, and yellowish green in a dark place. Example 2 In Example 1, the resin was low-density polyethylene (trade name “Novatech YF-30”, MFR 1.1 g / 10
And a density of 0.920 g / cm3, manufactured by Nippon Polychem Co., Ltd.), and foamed under the same composition and under the same conditions as in Example 1 to obtain a foam. The foam obtained had an apparent density of 0.06 g / cm 3, was white under the sun or a fluorescent lamp, and developed yellow-green in a dark place, but had a slightly lower luminance than that of Example 1.

Example 3 Example 1 was repeated except that 5.0 parts by weight of azodicarbonamide was used as a blowing agent, 2.0 parts by weight of zinc white and 0.5 parts by weight of zinc stearate were added as blowing aids. Foaming was performed under the same composition and under the same conditions as in Example 1 to obtain a foam. The resulting foam had an apparent density of 0.06 g / cm3
The color was pale yellow under the sun or fluorescent light and yellowish green in a dark place, but the luminance was lower than that of Example 1. Example 4 17 parts by weight of azodicarbonamide, 0.5 parts by weight of zinc white, 0.4 parts by weight of dicumyl peroxide, and 10 parts by weight of a luminous pigment (described above) were mixed with 100 parts by weight of low-density polyethylene (described above). The mixture was filled in a mold (25 × 370 × 720 mm) in a hydraulic press, sealed under pressure, heated at 150 ° C. for 35 minutes, and depressurized to take out the intermediate foam. The intermediate foam was immediately placed in a secondary mold (85 × 1060 × 2120 mm), heated by steam at 160 ° C. for 30 minutes by a jacket method, cooled, and taken out to obtain a foam. The resulting foam has a density of 0.
030 g / cm 3, which was pale yellow under sunlight or fluorescent light and yellowish green in a dark place, but had lower luminance than that of Example 1.

[0011]

[Table 1]

[0012]

As described above, according to the present invention, the foam obtained by mixing the luminous pigment with the polyolefin absorbs and accumulates the light of the sun and fluorescent lamps, etc. Has the property of gradually emitting and emitting light, for example, it develops yellow-green color in the dark, non-slip stairs, handrails, guidance signs,
It is suitable as decoration articles, toys, fishing gear, stationery, and the like.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA16 AD13 AG06 BA16 BB02 CC07Y CC22X CC32Y DA45 4H001 CA01 XA16 XA30 YA29 4J002 BB031 BB061 BB071 BB151 BB241 DG028 EK037 EK057 EK098 FD 006 FD 006 FD 006

Claims (3)

[Claims] 1. A luminous polyolefin foam obtained by mixing a luminous pigment with a polyolefin resin. 2. A method for producing a luminous polyolefin foam, which comprises mixing a foaming agent, a crosslinking agent and a luminous pigment with a polyolefin resin and foaming the mixture by heating. 3. The method according to claim 2, wherein the blowing agent is dinitrosopentamethylenetetramine.