JPH0612238B2 - UV reflection sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultraviolet reflecting sheet effective for hiding an object existing in an environment such as a snowy field.

(Prior Art) It has long been practiced to disguise field battles and to apply camouflage to military bases, military equipment, etc. that creates the illusion of an object in the environmental area.

For example, camouflage in the Arctic is based on white, and in the environment of forest areas, it is based on dark green or yellow to hide certain objects, and in areas where soil is the main, dark brown. It is a general camouflage color tone.

As a conventional method for hiding military objects in snowy areas, a white pigment such as titanium dioxide is used to white-process woven cloth, plastic sheet, etc., and the white cloth or white sheet is used. Methods of coating objects are known.

(Problems to be Solved by the Invention) However, snow does not absorb 70 to 90
%, The conventional white pigment such as titanium dioxide absorbs most of the irradiated ultraviolet light and hardly reflects it.

Therefore, there is a drawback that a portion covered with snow can be easily detected by a measuring instrument such as a remote sensitive computer equipped with a UV-transparent filter.

In order to solve such a drawback, there is already known a technique such as a white reflective sheet using powders of magnesium oxide, magnesium carbonate, barium sulfate, zircon oxide, and lead white, etc., in place of titanium dioxide (for example, Japanese Patent Publication No. -17711, Japanese Patent Publication No. 57-17712, Japanese Patent Publication No. 58-36108).

The white reflective sheet using the magnesium oxide or the like,
Although it has an ultraviolet ray reflecting effect more than that using titanium dioxide, the ultraviolet ray reflectance in the wavelength region around 300 nm is about 50%, which is not satisfactory because it can be discriminated sufficiently compared with snow. . Also, if lead white is used, it may cause environmental pollution depending on how to dispose of it even though it has expired.

(Means for Solving Problems) As a result of earnest research to solve the above-mentioned drawbacks of the prior art, the present inventor uses alumina as a white pigment, and thus has an extremely excellent ultraviolet reflectance near 300 nm. The inventors have completed the present invention by finding that an ultraviolet reflective sheet that does not cause environmental pollution can be obtained.

That is, the present invention is characterized in that it contains alumina as a white ultraviolet ray reflector, the particle diameter of the alumina is 0.3 to 5 μm, and the content is 20 to 500 parts by weight per 100 parts by weight of the base material. It is a UV reflective sheet for camouflage.

The present invention will be described in detail below. There is no particular limitation on the crystal form of alumina used in the present invention. Regarding the particle size, small particles have insufficient hiding power,
Also, dispersion becomes difficult. If it is too large, the hiding power is insufficient. The preferable range is 0.1 to 10μ
m, preferably 0.3 to 5 μm.

Since it is important that alumina has high whiteness and high reflectance with respect to ultraviolet rays, it is preferable that impurities such as iron content are small, and synthetic products are superior to those obtained by crushing natural products.

In the present invention, as the material of the reflection sheet which is a base material colored with the alumina, for example, polyamide-based, polyester-based, polyacrylic-based, acetate-based,
Polyvinyl chloride-based and polypropylene-based woven and non-woven fabrics,
Synthetic leather, synthetic resin impregnated cloth, polyethylene film, polypropylene film, polyamide film, polyvinyl chloride film, polyvinylidene chloride film, polyethylene terephthalate film, etc., including flexible or rigid sheet plates.

As a method of coloring a woven fabric, a non-woven fabric, a plastic film or the like with alumina according to the present invention, in the case of a woven fabric or a non-woven fabric, alumina is blended with a binder, for example, an acrylic resin, a polyurethane resin or the like, and an oil-based or water-based paint is used. A method of impregnating or coating this coating material on a woven fabric or a non-woven fabric, and in the case of synthetic fiber, alumina is blended to produce a colored fiber at the time of spinning without post-coating. A method of using a cloth or a non-woven cloth is also effective.

Further, as a method of coloring a plastic film material with alumina, (1) a method of compounding into a plastic at the time of making a film, that is, compounding alumina, and if necessary, a stabilizer, a plasticizer, an antioxidant, etc. Is blended and extruded by a T-die method, an inflation method, or formed into a film by a calendering method, or the like to form a film or a sheet.

(2) There is a method of applying coloring for ultraviolet reflection by applying a polymer solution or dispersion containing alumina on the surface of a plastic film manufactured by an appropriate method.

As the binder used after coating in the method (2), one having excellent adhesiveness to the base film is used.
Acrylic resins, polyurethane resins and the like are useful as the polymers used in this.

The amount of alumina used in the ultraviolet reflective sheet of the present invention is 30 to 500 parts, preferably 100 to 400, per 100 parts by weight of the binder resin (hereinafter, all parts are parts by weight) when the coating liquid is used. Used in the department. In the case of directly kneading into a fiber or film, it is used in an amount of 20 to 300 parts, preferably 50 to 200 parts, per 100 parts of the resin or compound as the base material. If the amount of alumina used is less than the above amount, the ultraviolet reflectance of the obtained sheet is not sufficient,
On the other hand, if the amount of alumina used is too large, the flexibility of the sheet decreases, or the processing becomes difficult, which is not preferable.

In order to impart flame retardancy to the ultraviolet reflecting sheet of the present invention, a metal, for example, a salt having crystal water such as aluminum hydroxide, basic oxide or gypsum, a phosphorus flame retardant, a halogen such as chlorinated paraffin, etc. A flame retardant, antimony trioxide, antimony pentoxide or a mixture thereof can be used. Alumina can be surface treated prior to use. Using alumina in a high concentration is a good method of increasing the reflectance of ultraviolet rays, but on the other hand, it causes deterioration of physical properties. Particularly when the fibers are mixed directly with each other, the affinity between the alumina and the resin as the raw material of the fibers is an important problem in terms of physical properties.

For this purpose, surface modification with a silane-based coupler or an organic metal chelate is a good method.

Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 150 g of a commercially available acrylic resin solution (for sealing a canvas, waterproofing, resin content 20%, containing a hydroxyl group) and toluene 300
400 g of alumina (average particle size: 2.5 μm) was added to the mixed solution of g and dispersed for 4 hours in a porcelain ball mill. 150 g of the above acrylic resin solution is added, dispersed for another 30 minutes, and taken out.

The above acrylic resin solution 7 per 100 parts of the taken-out dispersion liquid
0 part, 20 parts of toluene, and 2 parts of a 75% solution of a urethane crosslinking agent are added and stirred for 30 minutes to obtain a coating solution (1). A nylon cloth is dipped in a 10% ethylene acetate solution of an epoxy resin (solid) and dried to obtain a base cloth. The coating solution (1) is applied to both sides of the base fabric so that the amount of coating on one side is 150 g / m ² after drying and then dried. After leaving it for a week in the room, it will be used as a camouflage UV reflection sheet.

As a result of measuring the obtained sheet with a Hitachi 330 type self-recording spectrophotometer, the reflectance at 350 nm was 90.5%. Also, this sheet was subjected to an accelerated weathering test for 200 hours with a sunshine weatherometer, and then 350 nm.
The reflectance was 84.3%.

Example 2 300 g of alumina and 100 g of aluminum hydroxide were added to a mixed solution of 150 g of a commercially available acrylic resin solution (for sealing cloth, waterproofing, resin content 20%) and 300 g of toluene, and the mixture was dispersed in a porcelain ball mill for 4 hours. . 150 g of the above acrylic resin solution is added, dispersed for another 30 minutes, and taken out.

The above acrylic resin solution 7 per 100 parts of the taken-out dispersion liquid
Add 0 parts and 20 parts of toluene and stir for 30 minutes to obtain a coating solution (2). The coating liquid (2) is applied to both surfaces of a vinylon cloth so that the coating amount on one surface is 180 g / m ² after drying, and dried to give a camouflage ultraviolet reflective sheet (hereinafter referred to as sheet 2).

As a result of measuring the obtained sheet 2 with a Hitachi 330 type self-recording spectrophotometer, the reflectance at 330 nm was 89.2%. This sheet 2 was subjected to accelerated weathering test for 200 hours with a sunshine weatherometer
The reflectance of m was 84.7%. Also, the sheet 2 is 2 cm
When it was cut into a size of 10 cm and lit with a gas lighter, it showed self-extinguishing property.

Example 3 100 g of low molecular weight polyethylene, 1 of low density polyethylene
13g of 00g and 400g of alumina with 1 kneader
Knead for 20 minutes at 0 ° C. Once taken out, 200 g is cut out, kneaded with 400 g of low-density polyethylene in a kneader for 1 minute, and taken out. Make a sheet with a thickness of 0.5 m / m using a small-volume cutting press, and use the spectrophotometer described above to
When the reflectance at 50 nm was measured, it was 86.1%.

Example 4 In a porcelain ball mill of Example 5, 5 g of γ-glycidoxypropyltrimethoxysilane, 1 kg of toluene and 1 kg of alumina.
Is charged and dispersed for 20 hours. Acrylic resin solution containing carboxyl group (for waterproofing canvas, resin content 20%, viscosity 200
Add 500 g of poise, disperse for an additional 1 hour, and remove.

250 g of the dispersion liquid and the acrylic resin solution are mixed and stirred to obtain a coating liquid (4). A nylon base cloth treated in the same manner as in Example 1 (about 30 g / m ² ) had a coating amount of 10 when dried.
It is evenly coated on one side so as to be 0 g / m ² and dried.

When three coated sheets were stacked in the same direction and the coated surface was measured in the same manner as in Example 1, the reflectance at 350 nm was 88.5.
%Met.

Claims (1)

[Claims] 1. A white ultraviolet reflecting agent containing alumina, wherein the particle diameter of the alumina is 0.3 to 5 μm and the content is 20 to 500 parts by weight per 100 parts by weight of the base material. Ultraviolet reflective sheet for camouflage.