JPH11323311A - Near-infrared ray absorbing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compsn. having no color by compounding a near-infrared ray absorbing dye having an absorption also in a visible region and a fluorescent dye having a luminescence compensating the absorption in the visible region. SOLUTION: This near-infrared ray absorbing dye is selected as appropriate from the known products complying with the use. For this fluorescent dye, a dye which discolors the color of the near-infrared absorbing dye, i.e., a dye which has luminescence in the region of the absorption in visible region of the near-infrared ray absorbing dye and compensates its absorption in a visible region is used. Since most of near-infrared ray absorbing dyes have absorption in the region of 400-500 nm and/or 600-700 nm, a fluorescent dye having luminescence in this region is used. The fluorescent dye includes inorg. dyes (e.g. Y2 O2 S: Eu). When a near-infrared ray absorbing dye is colored yellow, a fluorescent dye having luminescence in the region of 400-500 nm, when colored blue, a fluorescent dye having luminescence in 600-700 nm, and when colored green, both fluorescent dyes are compounded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a near-infrared absorbing composition. The near-infrared absorbing composition according to the present invention is not colored and is suitable for uses such as near-infrared absorbing filters and stealth barcodes. In the present invention, “not colored” means that coloring that does not hinder practical use is permitted, and means that it is substantially not colored.

[0002]

2. Description of the Related Art The properties that a near-infrared absorbing dye should have are:
Needless to say, the near-infrared region (wavelength 700 to 1200 nm)
Has a large absorption. Numerous cyanine dyes, immonium dyes, squarylium dyes, phthalocyanine dyes, naphthalocyanine dyes, anthraquinone dyes, nickel-dithiol complex dyes, and the like have been proposed as near-infrared absorbing dyes. JP-A-51-135886, 56-143242, 5
8-1762, 58-13676, 60-23451,
63-295578, JP-A-4-174402, 5-9
No. 3160, 5-222302, Japanese Patent Publication No. 2-488
1, 6-18124). However, these conventionally proposed near-infrared absorbing dyes have absorption in the visible region in addition to absorption in the near-infrared region. Visible absorption is 4
It is often at a wavelength of from 00 to 500 nm or from 600 to 700 nm, and as a result, the near-infrared absorbing dye is often colored yellow or blue to green.

[0003]

A near-infrared absorbing filter for absorbing near-infrared rays emitted from a near-infrared ray source such as a plasma display using a near-infrared absorbing dye, and for absorbing heat rays of sunlight. When a heat ray shielding filter or the like to be attached to a window glass is produced, it is desirable that these filters be colorless, so that coloring of the near-infrared absorbing dye is a serious obstacle in practical use. Further, it has been considered to form a bar code that cannot be visually recognized, that is, a so-called stealth bar code, using an ink containing a near-infrared absorbing dye. However, in this case, coloring of the near-infrared absorbing dye is a major obstacle. Accordingly, an object of the present invention is to provide a near-infrared absorbing composition without coloring, a near-infrared absorbing filter and a stealth barcode using the same.

[0004]

The near-infrared absorbing composition according to the present invention comprises a near-infrared absorbing dye having an absorption also in a visible part and a fluorescent dye having a luminescence which cancels out the absorption in the visible part. In this method, the absorption in the visible region of the near-infrared absorbing dye is canceled by the coloring of the fluorescent dye to eliminate the coloring.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail. The near-infrared absorbing composition according to the present invention contains a near-infrared absorbing dye and a fluorescent dye. The near-infrared absorbing dye may be appropriately selected from known ones according to the application. For example, the following ones shown in Table 1 can be used.

[0006]

[Table 1]

[0007]

[Table 2]

[0008]

[Table 3]

[0009]

[Table 4]

The fluorescent dye used in combination with the near-infrared absorbing dye is one that makes the near-infrared absorbing dye colorless, that is, the near-infrared absorbing dye emits light at the absorption position of the visible portion and absorbs the visible portion. Is used. As described above, many near-infrared absorbing dyes have absorption at 400 to 500 nm and / or 600 to 700 nm.
Usually, a fluorescent dye which emits light at this position is used. Many such dyes are also known.
Fluorescent dyes that emit light at 400 to 500 nm are listed in Table-
3 illustrates a fluorescent dye having emission at 600 to 700 nm, respectively. In addition, although the inorganic fluorescent substance which emits light in 600 to 700 nm was also illustrated in Table 3, the fluorescent pigment in the present invention includes such an inorganic fluorescent substance.

[0011]

[Table 5]

[0012]

[Table 6]

[0013]

[Table 7]

When the near-infrared absorbing dye is colored yellow, a fluorescent dye which emits light at 400 to 500 nm in Table 2 is blended. -3 is mixed with a fluorescent dye which emits light at 600 to 700 nm. When the near-infrared absorbing dye is colored green, both of the fluorescent dyes in Tables 2 and 3 may be blended. The blending amount of the fluorescent dye with respect to the near-infrared absorbing dye is preferably as small as possible as long as the coloring of the near-infrared absorbing dye is eliminated, that is, the absorption of the visible portion of the near-infrared absorbing dye is offset. If the amount of fluorescent dye is large,
It becomes colored by the emission of the fluorescent dye itself. Generally, 0.1 parts of a fluorescent dye is used for 100 parts by weight of a near infrared absorbing dye.
It is preferable to mix them so as to be 10 to 10 parts by weight.

Since the near-infrared absorbing composition according to the present invention is not colored, it can be suitably used for various applications including near-infrared absorbing filters and stealth barcodes.
For example, when producing a near-infrared absorbing filter, a polymethyl methacrylate, polyethyl acrylate, polycarbonate, ethylene-vinyl alcohol copolymer, polyester, a near-infrared absorbing composition according to the present invention on a transparent synthetic resin such as polyvinyl butyral Is blended,
What is necessary is just to form a film by an ordinary well-known method. The content of the near-infrared absorbing composition in the filter is usually 0.5 to 80% by weight, preferably 5 to 70% by weight. If the content of the composition is too small, the absorption of near-infrared rays is insufficient, while if it is too large, the filter becomes expensive and the strength of the filter decreases.

When an infrared absorbing filter is manufactured by providing a coating layer containing the near-infrared absorbing composition according to the present invention on a transparent substrate, the near-infrared absorbing composition may be added to the above-mentioned resin together with an appropriate solvent. What is necessary is just to apply what was melt | dissolved on the base material. The film thickness of the filter may be appropriately determined depending on the application, but in the case of coating,
The thickness of the coating layer is usually 0.1 to 30 μm, preferably 0.5 to 10 μm.

When the near-infrared absorbing composition according to the present invention is used for printing a bar code or the like, the near-infrared absorbing composition according to the present invention is added to the above-mentioned resin or an appropriate film-forming material such as wax. If necessary, dissolved or dispersed using a solvent or the like, coated on a polyester or polyamide film to form a thermal transfer material,
What is necessary is just to print on an object using a thermal transfer printer etc. Examples of the wax include paraffin wax, microcrystalline wax, candelilla wax,
Carnauba wax, beeswax, spermaceti, montan wax, behenic acid, glycerin stearate fatty acid ester, α-olefin-maleic anhydride copolymer, and the like can be used.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the following, parts are parts by weight.

Example 1 Polymethyl methacrylate 30 parts Polyvinyl butyral 20 parts No. 101 near infrared absorbing dye 10 parts No. 105 near infrared absorbing dye 40 parts No. Fluorescent dye 201 3 parts Toluene 400 parts A solution comprising the above components was applied to a polyester film having a thickness of 150 μm so as to have a dry film thickness of 5 μm to produce a near-infrared absorption filter without coloring.

The near-infrared transmittance of this filter is expressed by BI
When measured using FTS-60A manufactured by O-RAD, the transmittance was 3 to 7% over 800 to 1200 nm. An attempt was made to operate the electrical equipment by placing this filter in front of the infrared remote control device, but the electrical equipment did not work, and it was confirmed that the infrared light used in the remote control device was blocked. Further, when this filter was mounted on the front surface of the full-color plasma display panel, a clear color image similar to that before mounting was obtained.

Comparative Example 1 A near-infrared absorbing filter was prepared in the same manner as in Example 1 except that no fluorescent dye was used. The infrared transmittance of this filter was almost the same as that of Example 1, and near infrared rays of the remote control device were completely shielded. However, the filter was colored yellow, and the color image of the full-color plasma display panel through the filter was strongly yellowish.

Example 2 Microcrystalline Wax (HiMiC2095 Nippon Seiwa Co., Ltd.) 53 parts Amide wax stearate (Amide AP-1, Nippon Kasei Co., Ltd.) 20 parts Hydrogenated petroleum resin (Alcon P-70, Arakawa Chemical Co., Ltd.) 25) No. of Table-1 No. 102 near-infrared absorbing dye, 2 parts No. 106 near infrared absorbing dye, 3 parts No. 203 fluorescent dye 0.1 part 301 fluorescent dye 0.1 part toluene 400 parts

The above components were mixed and wet-pulverized for 24 hours with a sand grinder to prepare a coating solution. 6μ thick
The above-mentioned coating solution was applied to a biaxially stretched polyethylene terephthalate film having a thickness of 1 μm using a wire bar to prepare a transfer ink ribbon. Using a thermal head, recording was performed on a 75 μm thick vinyl chloride resin film using the above-described ink ribbon. Although the record could hardly be confirmed visually, it was confirmed that it had a large near-infrared absorption capacity and was suitable for forming a stealth barcode.

Comparative Example 2 A transfer ink ribbon was prepared in the same manner as in Example 2 except that no fluorescent dye was used, and recording was performed on a vinyl chloride resin film by using a thermal head. But,
The record was greenish and easily visible, making it unsuitable for forming stealth barcodes.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09F 9/00 307 G09F 9/00 307Z

Claims (6)

[Claims] 1. An uncolored near-infrared absorbing composition comprising a near-infrared absorbing dye that also absorbs in the visible part and a fluorescent dye that emits light to offset the absorption in the visible part. 2. The near-infrared absorbing composition according to claim 1, wherein the fluorescent dye is an inorganic phosphor. 3. The near-infrared absorbing composition according to claim 1, further comprising a fluorescent dye having an emission wavelength of 400 to 500 nm. 4. The near-infrared absorbing composition according to claim 1, further comprising a fluorescent dye which emits light at 600 to 700 nm. 5. A near-infrared absorbing filter comprising the near-infrared absorbing composition according to claim 1. 6. A stealth barcode formed of an ink containing the near-infrared absorbing composition according to claim 1.