JPH024881B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a conventional optical filter. More specifically, the present invention relates to an optical filter having spectral characteristics close to the visibility of human eyes, which is made by blending a special near-infrared absorber with a thermoplastic resin. Optical filters with spectral characteristics close to the visual sensitivity are not only used in sunglasses, welding glasses, aircraft windows, and television filters, but in recent years, photodiodes have been used to improve the wavelength sensitivity characteristics of photoelectric conversion elements such as light-emitting diodes. It is important as a compensation optical filter. In this case, optical filters for protecting the naked eye such as sunglasses fulfill the purpose of preventing glare and eye fatigue.
It is also necessary to have spectral characteristics that match human visibility. In addition, among photoelectric conversion elements, photodiodes used in electronic shutters and character reading devices are required to have wavelength sensitivity characteristics close to that of the human eye. It is necessary to install an optical filter with spectral characteristics close to . Conventionally, two types of optical filters having spectral characteristics close to the visibility described above are known. Namely, there are known glass filters in which metal ions are mixed into glass and the absorption of the ions is utilized, and filters in which a glass plate or a resin plate is coated with a resin liquid containing an organic dye. However, in the case of the former glass filter, if it is used in a humid place,
The disadvantage is that the surface changes color and loses its spectral properties, so it is not only necessary to coat the glass surface with a thin film of silicone or special resin to protect it, but also to create filters of various dimensions. This involves the difficulty of cutting the glass. In addition, as for the latter filter coated with a resin solution containing various organic dyes, for example, a metal complex of a bisdithiol-α-ketone compound is mixed with a resin solution and coated on glass, and used as an optical filter. has been proposed (Tokuko Sho 46-3452, Sho 50
However, since these filters are manufactured by a coating method, it is difficult to obtain product specifications such as a constant thickness or a constant light absorption rate at a predetermined wavelength. Therefore, in order to obtain an optical filter with a certain standard, if these metal complexes are blended into resin and compressed or extruded, the metal complexes will lose their inherent ability to absorb light in the near-infrared region. Processing is limited to coating methods at around room temperature. For this reason, there is a strong demand for an optical filter that has spectral characteristics close to the luminous sensitivity and is made by blending a suitable organic dye into a resin that can be compressed or extruded. In view of this situation, the present inventors conducted detailed research on near-infrared absorbers that can be blended into thermoplastic resins and withstand compression and extrusion molding, and found that by using a benzenedithiol metal complex as a near-infrared absorber , an optical filter that can utilize its light absorption ability in the near-infrared and ultraviolet regions, has excellent thermal stability, processability, and weather resistance, and has spectral characteristics close to the visibility of the human eye, solving the drawbacks of the conventional optical filters described above. The inventors have discovered that it is possible to obtain a filter, leading to the present invention. That is, the present invention relates to a benzenedithiol-based metal complex represented by the general formula () (In the formula, X represents hydrogen, chlorine, bromine atom or methyl group, n represents an integer from 1 to 4, M represents nickel, palladium or platinum atom, and A represents quaternary ammonium) into a thermoplastic resin. To provide an optical filter having spectral characteristics close to visual sensitivity, which is characterized in that the filter is formulated with the following ingredients: The benzenedithiol-based metal complex used in the present invention has an extremely low light absorption rate in the visible region, absorbs in the ultraviolet region, and has an extremely large molar specific extinction coefficient at the maximum absorption wavelength in the near-infrared region. Optical filters not only have spectral properties close to those of the human eye, but benzenedithiol-based metal complexes have good thermal stability, do not absorb moisture, and are extremely chemically stable compounds even when in contact with water. It has been found that even if this compound is blended with a resin and subjected to normal compression or injection molding, the inherent maximum absorption wavelength hardly changes. The reason for this is that in benzenedithiol-based metal complexes, the metal atoms are strongly chelated by the sulfur atoms bonded adjacent to aromatic carbon atoms, which not only makes them chemically stable as metal complexes. , it is assumed that good thermal stability is obtained. The benzenedithiol-based metal complexes used in the present invention are described by Harry B. Gray et al. in Journal of the American Chemical Society (JACS) Vol. 88, pp. 43-50 and 4870-
It can be obtained by reacting benzenedithiols with nickel chloride, palladium chloride, and platinum chloride according to the method disclosed on page 4875, and then reacting this reaction solution with a quaternary ammonium halide. As benzenedithiols, benzene-1,2-dithiol, toluene-3,4
-dithiol, xylene-4,5-dithiol,
3,4,5,6-tetramethylbenzene-1,2
-dithiol, 4-chloro-benzene-1,2-
dithiol, 4,5,-dichlorobenzene-1,
2-dithiol, 3,4,5,6-tetrachlorobenzene-1,2-dithiol and 3,4,
5,6-tetraglomobenzene-1,2-dithiol and the like are used. Examples of the quaternary ammonium halide include tetraethylammonium bromide, tetrabutylammonium bromide, octyltriethyl bromide, cetyltriethylammonium bromide, and phenyltrimethylammonium bromide. Table 1 shows the molar specific extinction coefficients at maximum absorption wavelengths of typical examples of benzenedithiol-based metal complexes used in the present invention. Further, as the thermoplastic resin used in the present invention, any resin can be used as long as it does not have a large light absorption ability in the visible region and near-infrared wavelength region. For example, polyester resins such as polyethylene terephthalate, cellulose ester resins such as cellulose diacetate and cellulose triacetate, polyolefin resins such as polyethylene and polypropylene, polymethyl acrylate, and polymethacrylic acid.

[Table] Polyacrylic resins such as methyl, polyvinyl resins such as polyvinyl chloride, polyvinylidene chloride,
Polycarbonate, etc. Among these, polyacrylic resins and polycarbonate resins are desirable resins to use because of their good visible light transmittance and dimensional stability during processing. In addition, the blending ratio of the benzenedithiol metal complex to the resin in the present invention can be selected depending on the thickness of the resin plate when used as an optical filter and the desired light absorbance. In order to prevent the benzenedithiol-based metal complex from crystallizing from the resin, it is desirable to add about 0.05 to 5% by weight. The method for producing the optical filter in the present invention is not particularly limited, but the benzenedithiol-based metal complex is mixed with resin powder or pellets, melted, and then compressed or extruded to form an optical filter in a desired shape. can be created. Furthermore, the thermoplastic resin used in the present invention may contain additives such as stabilizers, antioxidants, plasticizers, and lubricants in order to improve its physical properties. Some substances can decompose complexes, so care must be taken when selecting them. In particular, it is better not to use trialkyl phosphites, which have the property of forming strong complex bonds with metals. Thus, an optical filter having spectral characteristics close to the visual sensitivity obtained by blending a benzenedithiol-based metal complex into a thermoplastic resin obtained by the present invention can be obtained by selecting the type of benzenedithiol-based metal complex according to the desired near-infrared spectral characteristics. Depending on the selection, it is possible to function as an optical filter having spectral characteristics close to the desired visibility. Hereinafter, the present invention will be explained in detail with reference to Examples, and all parts shown in the Examples indicate parts by weight. Example 1 Bis(1,2,3,4-tetrachloro-5,6
-dithiophenolate)nickel()tetra-
A mixture of 1.5 parts of n-butylammonium and 1000 parts of polymethyl methacrylate resin was injection molded at a cylinder temperature of 210°C and an injection pressure of 1300 Kg/ ^cm2 to obtain 1.0
A specimen with a thickness of mm was obtained. The obtained test piece exhibited a green color, and its spectral characteristics in the wavelength range of 350 to 1100 nm were measured using a multi-purpose self-recording spectrophotometer manufactured by Shimadzu Corporation, as shown in curve 2 in FIG. 1. As is clear from this curve, the maximum transmittance in the visible area is
70% or more, ultraviolet light below 400nm and 800nm
The transmittance in the near-infrared region of 950 nm to 950 nm was 5% or less (maximum absorption at 885 nm), and an optical filter was obtained which had spectral characteristics close to the visibility curve shown in curve 1 of FIG. Example 2 A mixture of 0.1 part of bis(1-methyl-3,4-dithiophenolate)nickel()tetra-n-butylammonium and 100 parts of polymethyl methacrylate resin was pressed at a temperature of 150°C and a pressure of 280 kg/cm ²
A test piece with a thickness of 1.0 mm was obtained by compression molding. The obtained test piece exhibits a light green color, and the maximum transmittance in the visible part of the wavelength range from 350 to 1100 nm is 85% or more, and the transmittance in the wavelength range below 400 nm and from 800 to 950 nm is 15%.
% (maximum absorption at 890 nm), an optical filter having spectral characteristics close to the visual sensitivity was obtained. Example 3 Bis(1-methyl-3,4-dithiophenolate)nickel()tetra-n-butylammonium in Example 2 was replaced with bis(1-methyl-3,4-dithiophenolate)nickel()tetra-n-butylammonium.
4-dithiophenolate) platinum ()tetra-n
- A test piece with a thickness of 1.0 mm was obtained in the same manner as in Example 2 except that butylammonium was used. The obtained test piece exhibits a green color, and the maximum transmittance in the visible part of the wavelength range of 350 to 120 nm is more than 80%.
An optical filter was obtained which has spectral characteristics close to the visibility of the human eye, with a transmittance of 10% or less in the wavelength range of 800 to 950 nm. Comparative Example 1 Bis[cis-1,2-bis(p-methoxyphenyl)ethylene] was used instead of bis(1-methyl-3,4-dithiophenolate)nickel()tetra-n-butylammonium in Example 2. -1,2-
Dithiolate] Nickel (maximum absorption wavelength 920nm)
The test piece was carried out in the same manner as in Example 2 except that the test piece was colorless and had completely lost its ability to absorb near-infrared light. Comparative Example 2 Bis(1-mercaptolate-2-naphthylate)nickel()tetra-n was used instead of bis(1-methyl-3,4-dithiophenolate)nickel()tetra-n-butylammonium in Example 2. -Butylammonium (maximum absorption wavelength 1100n)
The test piece was carried out in the same manner as in Example 2 except that m) was used, but the test piece obtained was colorless and had completely lost its ability to absorb near-infrared light.

[Brief explanation of drawings]

Figure 1 shows the visibility curve (curve 1) and Example 1.
The spectral characteristics (curve 2) of an optical filter prepared according to the description in .

Claims (1)

[Claims] 1 Benzenedithiol-based metal complex represented by the general formula () (In the formula, X represents hydrogen, chlorine, bromine atom or methyl group, n represents an integer from 1 to 4, M represents nickel, palladium or platinum atom, and A represents quaternary ammonium) into a thermoplastic resin. An optical filter having spectral characteristics close to visual sensitivity.