JPS6234980A - Composition for photochromic coating - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a photochromic coating material, which is used for photochromic eyeglass lenses, image materials (microimages, hologram recording), and the like.

Prior Art Conventional photochromic materials include silver halogenide,
Spiropyran and dithizone compounds are included. However, silver halide cannot be used in synthetic resins and has some disadvantages.
All of the latter had the drawback of slow color development and color erasure response speeds.

OBJECTIVES The present invention aims to provide a photochromic coating composition which can also be used for synthetic resins, allows the rate of decolorization to be arbitrarily selected, and overcomes the conventional drawbacks.

Structure The present inventor conducted extensive research to achieve the above object, and found that (R)n-X'' (R is a substituted or unsubstituted aromatic group or alkyl group,
Provided is a composition for photochromic coating, characterized in that it contains an organic anion of the type represented by n is an integer of 1 or 3, and X represents sulfur, silicon, tin, germanium or carbon, and an aromatic compound. It has been found that the above object can be achieved by the following method.

R is (T)rntaya' or (T)n1 to γ(
m=0.1,2; T=alkyl group, halogen, acetyl group, etc.); a substituted or unsubstituted aromatic group such as phenyl or naphthyl; or an alkyl group such as ethyl group.

The photochromic coating material of the present invention can produce various colors by selecting an appropriate aromatic compound, has excellent dimming properties, and can also freely select the rate of decolorization.

The general principle of the seven otochromic characteristics of the present invention is not exact, but it is approximately as follows.

An organic anion (for example, R-X-) emits an electron according to the following formula (1) upon irradiation with light.

bν R−X−−R−X4+ e″″ (1) R−X· is coupled according to the following formula (2) to form R−X−X−R
becomes.

2R-X.→R-X-X-R (2) The electrons created at this time enter the aromatic compound (A), producing a colored radical anion (A':).

Al. --A7 (31 Since R-X-X-R has a larger negative reduction potential than A, the generated radical anion is stable.

By appropriately selecting the reduction potential difference between R-X-X-R and A, the speed of color fading can be adjusted. The smaller the value of the reduction potential difference, ie, 1''R-X-X-RIIEAL, the faster the rate of decolorization.

The decoloring mechanism proceeds according to the following equation.

Aτ+R-X-X-R,: two A+R-X-X-R)
(4) R-X-X-R-ding → l't-X-+R-X
・ (5) 2R-X-→R-X -X
-R(6) The rate of reaction (4) is rate-limiting, and (5) is fast.

(6) is the same as reaction (2). The reaction is reversible and exhibits photochromic properties.

The photochromic coating composition of the present invention can be used not only for glass but also for synthetic resins such as polycarbonate, and is characterized in that the fading rate can be freely selected.

The aromatic compound (Al) used in the 7-otochronic coating material of the present invention is the corresponding (R)-X.
Compared to (R)n-X-X-(R)n, the absolute value of the reduction position (which becomes negative) is l'B l < I E l < l
R), -X-X-(R). Any substance that satisfies the condition 1(R)nX-A may be used, such as naphthalene, anthracene, tetra7ane, aromatic carzenyl compounds such as benzophenone, fluorenone, xanthone, thioxanthone, etc. In addition, any radical anion that is difficult to self-decompose may be used.

Organic anions are often easily degraded in air, so they are prepared in a nitrogen stream. For example, the 7-enyl thiolate anion reduces diphenyldisulfurion with sodium in an ethereal solvent under a nitrogen stream. This is dried and stored under nitrogen.

Specific examples of suitable organic anions include phenylthiolate anion, triphenylsilyl anion, triphenylstannonyl anion, triphenylgermanium ion, ethylthioleth anion, and the like.

A suitable weight ratio (f) of organic anionic aromatic compounds is f=
Aromatic compound/organic anion=3/1 to 2/3.

If this ratio (f) becomes larger than this, the relative concentration of anions decreases, the light absorption rate deteriorates, and the color density becomes insufficient. On the other hand, if this ratio (f) is smaller than this, the color density will not be sufficient.

Organic anions and aromatic compounds are dissolved in a polar solvent,
Immediately coat on glass or transparent resin such as polycarbonate.

A suitable film thickness for this photochromic coating is 1 to 50 .mu.m. If the film thickness is less than 1 .mu.m, proper coloring will not occur, and if it is more than 50 .mu.m, the adhesive strength will be poor.

Furthermore, a resin with low oxygen permeability is coated on top. The appropriate film thickness for the resin coating with low oxygen permeability is 5 μm to 1000 μm, and this film thickness is 5 μm.
If it is too small, it will be difficult to block oxygen, and if it is larger than 1000 μm, transparency will deteriorate. Examples of resins with low oxygen permeability suitable for use in the present invention and their suitable outer film thicknesses include polyacrylonitrile (5 to 1000 μ, m ), polyvinyl alcohol (10 to 1000 μ, m ), polyvinyl butyral (10 -1000 μm), polyvinylidene chloride (10-1000 μm), polyacrylonitrile (10-1000 μm), etc.

These coating operations are performed under a nitrogen stream.

Generally, the higher the color density, the better, and the faster the fading time, the better. However, a high color density and a fast fading time are contradictory matters. Therefore, the properties of the photochromic coating material are appropriately selected depending on the intended use of the photochromic coating material. For example, those with a long coloring life are used for image materials, and those with a short coloring life are used for chemical switches, displays, etc.

In this way, materials are selected depending on the purpose of use.

Next, the present invention will be explained in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 This example shows an example in which the color density is high and the fading rate is low.

Phenylthiolate anion 10 parts Thioxanthone sulfone 10 parts Tetrahydrofuran
80 parts were stirred at room temperature under a nitrogen gas atmosphere for 30 minutes and coated on a polycarbonate resin.

The thickness of the coating was 3μ. Furthermore, an aqueous solution of 20 parts of polyvinyl butyral resin and 80 parts of ethanol was coated on top of this and dried and hardened. The total coating thickness was approximately 20 microns.

The film exhibited a pale yellow color before being irradiated with light, but was transparent.

When this material was exposed to sunlight, it colored blue. It took approximately 0.5 mJ/ml of light energy to obtain a color density of 0.1. When I took it to a dark place, it returned to colorless color after about 6 hours.

Example 2 Phenylthiolate anion 10 parts Thioxanthone sulfide 10 parts Tetrahydro7ran
80 parts of the mixture was stirred at room temperature in a nitrogen atmosphere for 30 minutes, and then coated on a plate made of polyvinylidene chloride resin laminated with polyethylene resin. The thickness of the coating was approximately 10 microns. On top of this, further - polyethylene resin,
Polyvinylidene chloride resin was sequentially coated. The total coating thickness was approximately 50μ. When this material was exposed to sunlight, it developed a cyan color. When this was taken to a dark place, it became colorless in about 10 minutes.

This material is promising for photochrome glasses.

Example 3 10 parts of triphenylsilyl anion 10 parts of terphenyl (()()-@) 80 parts of tetrahydrofuran were stirred at room temperature for 30 minutes in a nitrogen atmosphere. I made a material wrapped in vinylidene chloride.

When this material was exposed to sunlight, it developed a cyan color. When this was taken to a dark place, it became colorless in about an hour.

Examples 4-6 Example 2 was repeated using the coloring materials shown in the table below. The results obtained are shown in the table.

(Left below) Effects As described above, the photochromic coating material of the present invention can also be used for synthetic resins, and the decoloring time can be freely adjusted by selecting the material depending on the application.

Claims (1)

[Claims] 1. (R)_n-X^- (R is a substituted or unsubstituted aromatic group or alkyl group, n is an integer of 1 or 3, X is sulfur, silicon, tin, germanium, or carbon 1. A composition for photochromic coating, characterized in that it contains an organic anion and an aromatic compound of the type represented by: