JPH0819403B2 - Photo-mochromic composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photothermochromic composition. More specifically, the present invention relates to a photothermochromic composition which exhibits a sharp color change upon irradiation with light or heating.

[Prior Art] Conventionally, as a material that is discolored by irradiation with light or heating, "solid physics", 21 , "photochromic material" described in 235-240 (1986) (Junetsu Seto) and the like are well known. There is. A photochromic material is a material that is colored by irradiation with ultraviolet rays or visible light, but is erased by applying heat, and has recently been used in the field for applications such as display (display) materials and recording materials used in photo printing processes. It is in the spotlight.

Examples of organic dyes used for irreversible photo-coloring materials and thermo-coloring materials include "Polymer Preprints", 35 , (8), 2462-2465 (1
986), "Photosensitive recording materials disclosed in" Research on photosensitive recording materials using halogenated polymers "(Nanaki Hiroshi et al.) Are known, and the recording materials include photosensitive paper and thermal recording paper. Is used for.

[Problems to be Solved by the Invention] However, when the material is required to have reversibility of coloring and decoloring, the above-mentioned conventional photochromic material is dark even if it is changed into a colored body by irradiation with light rays (such as ultraviolet rays). The color may fade or darken over time while stored in place. In addition, since many materials are expensive, they have not been put into practical use as display materials or recording materials.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and irradiates with a photothermochromic composition capable of repeating (reversibly) coloring and decoloring, that is, a light ray (ultraviolet ray, etc.). It can be colored by heating and decolored by heating, and such coloring and decoloring can be repeated, and both coloring and decoloring are stable at room temperature and are composed of inexpensive materials. The purpose is to obtain a photothermochromic composition.

[Means for Solving the Problems] The present invention provides at least one formula (I) in a molecule: An epoxy resin having a group represented by the general formula (II): (In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms or a phenyl group.)
A photothermochromic composition comprising a diaminodiphenylmethane derivative represented by

[Operation] The details of the principle of the present invention in which color is developed by irradiation of light rays and decolored by application of heat are still unknown, but it is presumed that it is due to the following mechanism, for example.

That is, at least one formula (I) in the molecule: An epoxy resin having a group represented by the formula and a diaminodiphenylmethane derivative are copolymerized to obtain the formula: A chain represented by is generated. This chain is broken by irradiation of light rays (ultraviolet rays, etc.) To a quinone radical (colored body) represented by.
When this is heated to a temperature higher than the glass transition temperature of the epoxy resin, for example, it is recombined and the radicals disappear, whereby the color disappears.

EXAMPLES The photothermochromic composition of the present invention comprises at least one compound of formula (I): An epoxy resin having a group represented by the general formula (II): (In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms or a phenyl group.)
And a diaminodiphenylmethane derivative represented by

In the epoxy resin having at least one group represented by the formula (I) used in the present invention, the position of the Br group bonded to the benzene nucleus is not particularly limited and may be any position. The number of the group represented by the formula (I) contained in one molecule of the epoxy resin needs to be at least one from the viewpoint of the radical generation mechanism as described above. It is sufficient that at least one group represented by (I) is contained in one molecule, and the number is not limited. The molecular weight of the epoxy resin is not particularly limited, and any epoxy resin that can be usually produced may be used. At least one group represented by the above formula (I) is used.
Specific examples of the epoxy resin having a unit, for example, a brominated epoxy resin generally referred to as a flame-retardant epoxy resin, EBL-240, ESB-340, ESB-500 (above, Sumitomo Chemical Co., Ltd.) DX-248-B70 (Shell); DER5
11-A80, DER542 (above, manufactured by Dow Chemical Co.) and the like.

Further, the general formula (II) used in the present invention: (In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms or a phenyl group.)
Specific examples of the diaminodiphenylmethane derivative represented by are, for example, diaminodiphenylmethane (in the general formula (II), R ¹ , R ² , R ³ , and R ⁴ are all hydrogen atoms), dimethyldiaminodiphenylmethane (the general formula ( II), R ¹ and R ³ are CH ₃ ; R ² and R ⁴ are hydrogen atoms), and tetramethyldiaminodiphenylmethane (in the general formula (II), R ¹ , R ² , R ³ and R ⁴ are both
CH ₃ ), dichlorodiaminodiphenylmethane (in the general formula (II), R ¹ and R ³ are Cl; R ² and R ⁴ are hydrogen atoms), and the like.

The epoxy resin having a group represented by the formula (I) and the diaminodiphenylmethane derivative represented by the general formula (II) are required to be stoichiometrically equivalent to each other in consideration of their reactivities. There is.

Incidentally, a reactive diluent usually used for controlling the viscosity of the obtained composition or improving the mechanical properties after curing may be appropriately added. An epoxy resin reactive diluent having a halogen atom in the molecule is preferably used in order not to lower the color development sensitivity due to light irradiation. Examples of such reactive diluents include halogenated phenyl glycidyl ethers BR-250 and BROC.
(Nippon Kayaku Co., Ltd.), cresol novolac type epoxy resin and formula And the like. If necessary, a solvent such as methyl ethyl ketone or methyl cellosolve may be appropriately used.

The composition of the present invention thus obtained has flame retardancy based on halogenation, and can be formed into any shape and form such as a film or a cast, and if desired, a substrate such as a glass cloth. It can be in the form of a composite material with. In addition, the physical properties of the composition may be appropriately adjusted by further adding another epoxy resin including a crosslinking agent.

Before use, the composition of the present invention is preferably heated and cured in advance. The present invention is not limited to such heating conditions, and can be heat-cured like ordinary epoxy resins.

The cured composition of the present invention is colored in blue by irradiating light rays (such as ultraviolet rays), and as a means for irradiating such light rays, the wavelength of the light rays is to efficiently generate a short wavelength of 400 nm or less. Any light source generally used may be used, and for example, a xenon lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp or the like can be used as a light source. The irradiation time of ultraviolet rays cannot be unconditionally determined because it depends on the distance between the light source and the composition, the brightness of the light source, and the like, but it is usually 1 minute or less under continuous irradiation.

Heating is applied when the colored composition of the present invention is decolored. Although the heating conditions cannot be determined unconditionally, it is preferable that the glass transition temperature of the epoxy resin or higher, the heating temperature is 100 to 200 ° C., and the heating time is 5 minutes or less.

By applying the above-mentioned irradiation of ultraviolet rays and heating, coloring and decoloring of the composition of the present invention are repeated with good reproducibility.

Next, the photothermochromic composition of the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

Examples 1 to 5 Compositions were prepared by adjusting the raw materials so that the compositions shown in Table 1 were obtained. The composition obtained was plain woven glass tape (thickness
(For 0.7 mm), squeeze between rolls, and then heat at 100 ° C for 3 hours and then at 150 ° C for 3 hours to cure the composition.
It was cut into a size of 5 mm × 50 mm × 0.7 mm (t) to obtain a test piece (the composition is colorless and transparent). Photothermochromic property and discoloration degree were evaluated using the obtained test pieces according to the following methods.

(Photothermochromic property) GS mini conveyor UV irradiation device ASE-20 (Nippon Battery Co., Ltd.)
(Made by Japan), the test pieces obtained in Examples 1 to 5 are placed on a conveyor, and the ultraviolet ray generating lamp (Japan Battery (Japanese battery (length: 25 cm)) is laid out in a direction perpendicular to the longitudinal direction of the conveyor. Co., Ltd., electric power: 80 W / cm), set the distance between the conveyor and the lamp to be 10 cm, irradiate ultraviolet rays at a conveyor speed of 2 m / min, and check the color of the test piece after irradiation. It was Table 2 shows the results.

Next, after cutting off a part of the test piece after UV irradiation, after storing for 3 months in a dark room (room temperature: about 20 ° C),
The color change of the test piece was examined. Table 2 shows the results.

The absorption spectrum of light before and after ultraviolet irradiation was examined on the test piece obtained in Example 1 using an absorptiometer (manufactured by Nippon Kogaku Co., Ltd., product number: GP-250). The results are shown in (a) and (b) of FIG. 1, respectively.

Next, the test piece obtained in Example 1 irradiated with ultraviolet rays was heated at 180 ° C. for 1 minute using a warm air blower, and then the light absorption spectrum was examined in the same manner as above. The result is shown in FIG. 1 (c). After further irradiating the heated test piece with ultraviolet rays in the same manner as described above, the absorption spectrum of light was examined. The results are shown in Fig. 1 (d).

(Discoloration degree) Eleven test pieces obtained in Example 2 were prepared, and the conveyor speed for each test piece was changed as shown in Table 3 above (measurement of photothermochromic property).
Ultraviolet irradiation was carried out in the same manner as in, and the change in absorption spectrum of light was examined. The results are shown in FIG. 2 and Table 3. In Fig. 2, each number indicates an experiment number.

From the results shown in FIG. 1, the test piece obtained in Example 1 was irradiated with ultraviolet rays to have wavelengths of 350 nm and 620 nm.
It is understood that light is absorbed in the vicinity of, but the absorption of light disappears by heating. Further, it can be seen that there is almost no change in the light transmittance even when irradiation with ultraviolet rays and heating are repeated, and the operation can be repeated with good reproducibility.

The same operations as described above were performed on the test pieces obtained in Examples 2 to 5, but the results were almost the same as those shown in FIG.

Based on the results shown in Fig. 2, as shown in Fig. 3, the horizontal axis is the conveyor speed and the vertical axis is the absorbance at wavelength 632 nm. As a result, the absorption peak value and the conveyor speed, that is, the ultraviolet irradiation amount are plotted. From this relationship, it can be seen that the degree of discoloration is uniquely determined by the amount of ultraviolet irradiation.

EFFECTS OF THE INVENTION The photothermochromic composition of the present invention is inexpensive and can be easily produced, can be repeatedly used as a colored body or a decolorized body, and has excellent storage stability at room temperature. It is a thing. Therefore, there is an effect that it can be suitably used for, for example, an optical recording material, a display material, an ultraviolet dosimeter, and the like.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the light wavelength and the light transmittance before and after the ultraviolet irradiation of the photothermochromic composition obtained in Example 1 of the present invention, and FIG. 2 is the example 2 of the present invention. Showing the relationship between the absorption wavelength and the absorbance when the obtained photothermochromic composition is irradiated with ultraviolet rays.
The figure is a graph showing the relationship between the conveyor speed and the absorbance when the photothermochromic composition obtained in Example 2 of the present invention was irradiated with ultraviolet rays.

Claims (2)

[Claims] 1. At least one formula (I) in the molecule: An epoxy resin having a group represented by the general formula (II): (In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms or a phenyl group.)
A photothermochromic composition comprising a diaminodiphenylmethane derivative represented by: 2. A photothermochromic composition according to claim 1, which contains an epoxy resin reactive diluent containing a halogen atom in the molecule.