JPH08120198A - Coating for forming infrared ray sensing transparent film capable of manifesting strong emission luminance - Google Patents

Abstract

PURPOSE: To obtain the subject coating, comprising a mixture prepared by mixing a specific fluorescent powder with a metallic alkoxide, a solvent, water and a hydrolysis promoting catalyst in a specified proportion, good in film smoothness even in the case of a thin film, excellent in transparency and useful for securities such as various bills, gold notes or cards. CONSTITUTION: This coating comprises a mixture prepared by mixing (A) 100 pts.wt. fluorescent powder, comprising a fused complex fluoride having the composition of the formula, (1-x-y)PbF2 .xYbF3 .yErF3 [(x) and (y) are each 0.1-0.2 and 0.01-0.04 expressed in terms of weight ratios] and having <=0.5μm average particle diameter with (B) a metallic alkoxide (e.g. a methoxide or an ethoxide of Si, Al, Zr or Ti) in an amount of 10-900 pts.wt. expressed in terms of a metallic oxide, (C) 100-5000 pts.wt. solvent (e.g. methanol or butanol), (D) 20-400 pts.wt. water and (E) 0.5-50 pts.wt. hydrolysis promoting catalyst (e.g. hydrochloric acid, oxalic acid or aqueous ammonia).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention, when used for the formation of the infrared sensing transparent film, 30 foot-lamberts with infrared radiation of the low density of the film thickness in a thin film of 0.1 to 3 m, for example 10 mW / cm ² The present invention relates to a coating material for forming an infrared-sensitive transparent film exhibiting a strong emission brightness as described above.

[0002]

2. Description of the Related Art Conventionally, an infrared sensitive transparent film has been generally applied to various kinds of cash vouchers and securities for the purpose of preventing forgery and alteration, and for various kinds of cards for the purpose of security of authenticity judgment. In addition, the paint used for forming these infrared sensing transparent films is, for example, Japanese Patent Publication No. 3-235.
As described in Japanese Patent Publication No. 47, it is also known that it is basically composed of a mixture of a fluorescent powder, an inorganic binder such as water glass, and a solvent, and various fused complex fluorides are used as the fluorescent powder. There is.

[0003]

On the other hand, in recent years, the sophistication of printing and the diversification of color tones of various products to which the above-mentioned infrared-sensitive transparent film is applied are remarkable, and accordingly, the reduction of the product value is prevented. For that purpose, the infrared sensing transparent film is required to have a higher transparency, and for this purpose, it is necessary to reduce the thickness of the infrared sensing transparent film to about 0.1 to 3 μm. In the case of forming an infrared-sensitive transparent film using this, the film thickness is 0.1 to 3
Even a thin film of μm film smoothness is poor, and to light emission luminance is low in the molten composite fluorides powder constituting the coating composition (fluorescent powder), for example, most emission in infrared radiation of a low density of 10 mW / cm ² In the present situation, therefore, the demand for further thinning of the infrared-sensitive transparent film cannot be satisfied satisfactorily.

[0004]

Therefore, the present inventors have
From the above viewpoints, as a result of research to solve the problems of the above-mentioned conventional infrared-sensitive transparent film forming paints, as a result, fluorescent powder has an average particle size of 0.5 μm or less and a composition formula : (1-x-y) PbF 2 · xYbF 3 · yErF 3, ( provided that the weight ratio, x: 0.1~0.2, y: 0.0
1 to 0.04), and a predetermined amount of a metal alkoxide as an inorganic binder, to which a usual solvent, a catalyst for promoting hydrolysis, and water are added. When an infrared-sensitive transparent film is formed by using a coating material composed of a mixture obtained by mixing, even if the film thickness is 0.1 to 3 μm, the film smoothness is good,
Since the fluorescent powder composed of the above-mentioned fused complex fluoride exhibits extremely strong emission luminance, the research result that the emission luminance of 30 foot-trans belt or more is sufficiently satisfactory for practical use is obtained by infrared irradiation of low density of 10 mW / cm ² , for example. It was.

The present invention has been made based on the above research results, and has a composition formula: (1-x-y) PbF ₂ .xYbF ₃ .yErF ₃ (where x: 0 by weight). 1 to 0.2, y: 0.0
1 to 0.04), and a fluorescent powder having a mean particle size of 0.5 μm or less, which is composed of a molten complex fluoride:
10 parts by weight to 100 parts by weight of metal alkoxide: metal oxide, solvent: 100 to 500 parts by weight
A coating material for forming an infrared-sensitive transparent film showing strong emission brightness, which comprises a mixture of 0 parts by weight, water: 20-400 parts by weight, and a catalyst for promoting hydrolysis: 0.5-50 parts by weight. It has characteristics.

In the coating material of the present invention, YbF ₃ in the molten composite fluoride powder which constitutes the fluorescent powder of the coating material of the present invention.
The ratios of Erb ₃ and ErF ₃ are empirically determined, and the ratios of YbF ₃ and ErF ₃ are each 0.1%.
If the ratio is less than 0.01 and less than 0.01, or if these ratios exceed 0.2 and 0.04, respectively, the desired strong emission brightness cannot be secured, and the ratio of YbF ₃ is 0.1 to 0.1.
When 0.2 and ErF ₃ are set to 0.01 to 0.04, strong emission brightness is exhibited. Further, the average particle size of the above fused complex fluoride powder is set to 0.5 μm or less,
This is because if the average particle size exceeds 0.5 μm, the transparency of the formed transparent film will be impaired, and it is desirable to set the average particle size to 0.1 μm or less.

Further, the metal alkoxide constituting the coating material of the present invention has a binding action, so that the ratio thereof is the ratio to 100 parts by weight of the above-mentioned fluorescent powder (hereinafter the same) and is 10 in terms of metal oxide. If the amount is less than 100 parts by weight, a strong thin film having high adhesion cannot be formed. On the other hand, if the ratio is more than 900 parts by weight, the viscosity increases, and it becomes difficult to form a thin film having a thickness of 0.1 to 3 μm. Therefore, the ratio is 10-9 in terms of metal oxide.
The amount is defined as 00 parts by weight, preferably 25 to 500 parts by weight.
The metal alkoxide may be Si, Al, Z.
The use of methoxides, ethoxides, propoxides and butoxides of r and Ti, and their isomers is preferred.

The solvent, water, and catalyst are essential components for forming a thin film, and the proportion of any one of the solvent, water, and catalyst is solvent: less than 100 parts by weight, water: 2
If the amount is less than 0 parts by weight and the catalyst is less than 0.5 parts by weight, it is difficult to form a satisfactory thin film, and similarly, in any proportion of these, solvent: 5000 parts by weight, water: 400
When the amount exceeds 50 parts by weight and the catalyst: 50 parts by weight, cracks are easily generated in the formed thin film. Therefore, the ratio should be 100 to 5000 parts by weight of solvent, preferably 100 to 30 parts by weight.
00 parts by weight, water: 20 to 400 parts by weight, preferably 30
.About.250 parts by weight, and catalyst: 0.5 to 50 parts by weight, preferably 0.5 to 30 parts by weight. As the solvent, it is desirable to use methanol, ethanol, isopropanol, butanol, methyl ethyl ketone, methyl isobutyl ketone, ethylene glycol, propylene glycol, and as the catalyst, hydrochloric acid, nitric acid, oxalic acid, and ammonia water can be used. desirable.

Further, if necessary, one or more of a curing agent, a cross-linking agent, a pH adjusting agent, a defoaming agent, and a wetting agent are added to the coating material of the present invention in a predetermined ratio and mixed. However, the characteristics of the paint are not impaired. In addition, the infrared-sensitive transparent film, the coating is applied to the product,
It is formed by coating with a predetermined film thickness by means such as printing or spraying, heating if necessary to remove the solvent, and drying.

[0010]

EXAMPLES Next, the coating material of the present invention will be specifically described by way of examples. As raw materials, lead fluoride (PbF ₂ ), ytterbium fluoride (YbF ₃ ), erbium fluoride (ErF)
₃ ) and a complex fluoride of Na and Y (NaYF ₄ ) are prepared, these raw materials are mixed in a predetermined ratio and mixed, and then heated in the atmosphere to a predetermined temperature within a range of 800 to 1200 ° C. By melting, cooling, and pulverizing, fluorescent powders A to U made of fused complex fluoride powder having the composition formula and average particle size shown in Table 1 were manufactured. Then, in each of these fluorescent powders A to U, a metal alkoxide as an inorganic binder, a solvent, and
Water, and a catalyst, further Na as the inorganic binding material ₂ O-
Coatings 1 to 20 of the present invention and conventional coatings were prepared by blending and dispersing SiO ₂ water glass.

Next, various paints obtained as a result are
It is coated on a PET (polyethylene terephthalate) film substrate and dried at 100 ° C. to form an infrared-sensitive transparent thin film having the thickness and fluorescent powder content shown in Tables 4 and 5,
For the purpose of evaluating the transparency of this infrared-sensitive transparent thin film, the light transmittance at a wavelength of 550 nm was measured, and the measurement results are shown in Tables 4 and 5 against the light transmittance of the PET film used as the substrate of 89%. It is shown as a relative ratio, and for the purpose of evaluating the emission brightness of the infrared-sensitive transparent thin film,
An infrared ray having a wavelength of 80 nm, respectively irradiated at a density of 10 mW / cm ² and 100 mW / cm ^2, the emission luminance was measured, the measurement result is also shown in Tables 4 and 5.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

[0016]

[Table 5]

[0017]

From the results shown in Tables 1 to 5, the coatings 1 to 20 of the present invention were formed even if the thickness was reduced to 0.1 to 3 μm to ensure excellent transparency. In the infrared sensitive transparent thin film, in comparison with the one formed by using the conventional paint, the infrared emission of high density of 100 mW / cm ² as well as the infrared emission of low density of 10 mW / cm ² gives much stronger emission brightness. It is clear to show. As described above, according to the coating material of the present invention, even if a thin film having a thickness of 0.1 to 3 μm is used to ensure transparency, for example, 10 mW /
Irradiation with a low density of cm ² makes it possible to form an infrared-sensitive transparent film that exhibits sufficient emission brightness without any practical problems, so it can be used as an infrared-sensitive film for various products that require transparency. Industrially useful effects such as application can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Shoji Ishiwata 1-297, Kitabukuro-cho, Omiya-shi, Saitama, Central Research Laboratory, Mitsubishi Materials Co., Ltd. (72) Etsushi Kimura 1-297, Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Central Research Institute Co., Ltd.

Claims (1)

[Claims] 1. A composition formula: (1-xy) PbF ₂ .xYbF ₃ .yErF ₃ (where x: 0.1 to 0.2 and y: 0.0 are weight ratios).
1 to 0.04), and a fluorescent powder having a mean particle size of 0.5 μm or less, which is composed of a molten complex fluoride:
10 to 900 in terms of metal alkoxide: metal oxide based on 100 parts by weight
Parts by weight, solvent: 100 to 5000 parts by weight, water: 20 to 400 parts by weight, hydrolysis-accelerating catalyst: 0.5 to 50 parts by weight, and a strong luminescence characterized by comprising a mixture. Infrared-sensitive transparent film forming paint showing brightness.