JPH0696622B2 - Polymeric photochromic compound - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel diene polymer compound having photochromic properties, and more specifically, to various recording / memory materials, display materials, and photosensitive materials for lasers. Material,
The present invention relates to a polymeric photochromic compound which is particularly excellent in heat stability and can be used as a photosensitive material for printing / copying, a material for optical filters / masking materials, and the like.

[Conventional technology]

Conventionally, various compounds such as spiropyran-based compounds, triphenylmethane-based compounds, and azobenzene-based compounds have been proposed as compounds having photochromic properties.

On the other hand, although there are few examples of synthetic polymer-based photochromic compounds, the present inventors have previously introduced a photochromic photosensitive material composed of poly-2,3-diphenylbutadiene (European Polymer Journal (Eur. Pol.
ym. J.) Vol. 18, p. 15, 1982].

[Problems to be solved by the invention]

The research on photochromic compounds is old, and many compounds are already known as described above, and recently, expectations are increasing as a photoresponsive functional material especially in the advanced field. However, conventional known substances have poor thermal stability in each colored state during photochromic conversion, and are therefore prone to change over time, which is a major obstacle to practical use. For example, when it is used for an optical recording medium, the storage stability of the recorded signal is poor in response to the writing light, and it gradually disappears or the contrast is deteriorated to deteriorate the repetitive life. This tendency is particularly noticeable during humidification. It was possible to avoid the essential problems such as.

On the other hand, in the case of poly-2,3-diphenylbutadiene, which is one of the polymeric photochromic compounds previously found by the present inventors, the thermal stability of the colored state is improved by several steps as compared with known substances. However, in the presence of oxygen, there are some problems when they are irreversibly transferred to a phenolanthrene derivative, and further improvement studies are desired.

The object of the present invention is to improve the thermal stability over time, which is a common fundamental problem that has been a hindrance to the practical development of photochromic systems, is significantly improved, even in the presence of oxygen,
It is intended to provide a compound capable of exhibiting stable and reversible photochromic properties.

[Means for solving problems]

The present inventors have conducted extensive studies to achieve the above-mentioned object, and as a result, a novel polymer system composed of a diene polymer as described below, which is excellent in thermal stability over time as not found in known photochromic compounds. Found a photochromic compound,
The present invention has been completed.

That is, the present invention is a homopolymerization containing a cis-1,4 structural unit represented by the general formula [I] as an essential component. The present invention relates to a novel polymer type photochromic compound comprising a polymer or a copolymer and having a molecular weight of 5,000 or more, preferably 10,000 or more. (However, R _{1 to} R ₄ represent a hydrogen atom or an alkyl group, X and Y are an aromatic ring or a heteroaromatic ring in which the α-position to be a reactive position in the photocyclization is alkyl-substituted, ], (R ₅ represents an alkyl group, R ₆ and R ₇ represent a hydrogen atom or an alkyl group, Z represents S, O, N—R ₈ , Se, and R ₈ represents a hydrogen atom or an alkyl group), or , The general formula [b], (R ₉ and R ₁₃ represent an alkyl group, and R _{10 to} R ₁₂ represent a hydrogen atom or an alkyl group). The substituted alkyl group introduced into these is preferably a lower alkyl group such as methyl, ethyl or butyl. Other examples of X, Y Etc. and derivatives thereof, which can be expected as systems having different absorption wavelength regions, that is, different color tones, but are somewhat complicated in terms of synthesis.

The polymer type photochromic compound used in the present invention is produced, for example, as follows. That is, first, the general formula [I
I] the diene monomer represented by (However, R _{1 to} R ₄ and X and Y are the same as those in the formula [I]) General formula [II
I] (R ₁ , R ₂ and X are the same as in formula [II]) And a compound represented by the following general formula [IV] (R ₃ , R ₄ and Y are the same as those of the formula [II]), diethyl ether Titanium tetrachloride is added and reacted in the presence of zinc in an ether solvent such as toluene, tetrahydrofuran or dioxane.
The reaction temperature is -40 ° C to 200 ° C, preferably -20 ° C to 120 ° C. It is represented by the following general formula [V] obtained in this way From this compound, a monomer represented by the general formula [II] is obtained through a dehydration reaction with potassium hydrogen sulfate or the like.

Then, the diene monomer is homopolymerized or copolymerized with another monomer to obtain a photochromic polymer compound containing at least partially the cis-1,4 structural unit represented by the general formula [I]. Get

The polymerization method may be any method such as radical polymerization and ionic polymerization. Generally, in the polymerization of a diene monomer, cis-1,4, trans-1,4 and 1,2- (3,4-) bonds are generated as constitutional units, and the generation ratio varies depending on the polymerization method. . In the photochromic system, it is cis-1,4 units that can participate in the reversible photochromic ring-opening ring closure reaction, as illustrated in the following formula, and therefore, to obtain the necessary cis content depending on the purpose, Just choose the conditions.

The molecular weight of the polymer is 5000 or more, preferably 1000
0 or more is required. This is because in this type of photochromic system, a non-reactive trans 1,4-body is likely to form a partially unreactive trans 1,4-isomer as a side reaction during the light-induced ring-opening → ring-closing conversion reaction. Is big. Even in the system, in the early stage of research where a sufficient degree of polymerization could not be obtained, the influence of the isomerization side reaction could not be excluded, but by achieving the required molecular weight region as described above in the subsequent study, We have obtained a system with excellent repeated life and excellent handling stability. As a result, the extinction coefficient (ε) of the ring-closed colored system after the repeated reaction of the ring-opened ring-closed system with light has a high retention rate in comparison with a low molecular weight system in the system having a molecular weight of 5000 or more, preferably 10000 or more, It was confirmed that the material could have remarkably superior characteristics.

In the present invention, the obtained polymer mainly composed of the general formula [I] generally has a high glass transition temperature and therefore exhibits the following practically preferable physical properties. This kind of photochromic compound can be used in both liquid state and solid state, and particularly when it is put to practical use in the solid state, it is characterized by the system that the temperature is lower than the glass transition temperature, and more particularly in the temperature range of the melting point or higher. , Reversible ring-opening ring-closing system conversion rate by light is remarkably different. Based on this, switching operation or optical recording memory operation such as recording, reproducing and erasing can be effectively performed with high accuracy. . However,
As mentioned above, since the system is thermally extremely stable, it is also a characteristic of this system that the conversion reaction does not occur only by heat without a light source. For example, at a temperature near the melting point, a signal is written with a light source close to the wavelength range that exhibits large absorption, and the system after that is kept below the glass transition temperature to stabilize both the unrecorded area and the recorded area against heat and light. It can achieve various states and has high reliability during reading. Thus, it can be put to practical use as a system that is stable not only thermally but also optically and is excellent in handleability.

Furthermore, by copolymerizing the diene-based monomer with another type of monomer, it is possible to set a wider range of thermal properties (glass transition temperature, melting point, etc.), mechanical properties, processability, and the like. There is no end. It is also possible to use a mixture with another polymer. Examples of other monomers for copolymerization include butadiene, isoene and other diene-based monomers, methacrylic acid esters, acrylic acid esters, styrene, α-methylstyrene, acrylonitrile, ethylene, propylene, butene, and other olefin monomers and derivatives thereof. can give.

The photochromic photosensitive material composed of the diene-based polymer thus obtained is excellent in stability of each colored state of the photochromic structural unit, and is superior to the fulgide system, which has been considered to be included in conventionally known photochromic compounds, to several stages. It has thermal stability and is stable even in the presence of oxygen, and when used in combination with a polymer effect, it is possible to exhibit excellent properties in terms of repeatability and life.

As a result, the photochromic system can be applied to various fields as described above, but is particularly useful as an optical recording / memory medium or display material capable of being repeatedly written / read / erased.

The present invention will be described in more detail below with reference to examples.

Example 1 Under a nitrogen atmosphere, 98 g (1.5 mol) of zinc powder and tetrahydrofuran 2 were placed in 5 reactors, and 143 g (0.75 mol) of titanium tetrachloride was slowly and dropwise added while keeping the temperature below -10 ° C. After that, tetrahydrofuran solution 1 of 84 g (0.5 mol) of 3-acetyl-2,4,5-trimethylthiophene was added dropwise. After stirring at room temperature for 2.5 hours, it is poured into 5% 10% aqueous potassium carbonate solution and extracted 3 times with ether 1. After dehydrating the organic layer with a desiccant, the ether was distilled off, and the resulting reaction product mixture was separated by column chromatography.
Purified to give 2,3-di (2,4,5-trimethylthienyl) 2,3
-Butanediol was obtained. The yield was about 15%.

Then, 50 mg of potassium hydrogensulfate was added to 2.5 g of the obtained diol compound, and the mixture was heated at 100 ° C. for 1 hour while stirring under reduced pressure. Then add ether to the residue in the reaction vessel,
After filtration, the filtrate was washed with water, dehydrated and dried, concentrated and purified to give a colorless oily or semi-solid product in a yield of 10%. This thing
Dissolve in CDCl ₃ , measure ¹ H-NMR, δ = 2.30 to 2.40, And respectively 5.07 to confirm peak corresponding to Ar-CH ₃ and C = CH _2.

Next, using this diene compound as a monomer, the following polymerization was carried out to obtain a target polymer. That is, 2.5 g of the diene compound
Is dissolved in 100 ml of benzene, 3 mg of azobisisobutyronitrile (AIBN) is added, and after reacting under nitrogen at 60 ° C for 17 hours, the reaction product is dropped into a large amount of methanol and polymerized by reprecipitation.
1.9 g was obtained. Number average molecular weight is GPC (polystyrene conversion)
The measurement result was about 16,000.

Using this polymer, a photochromic ring-opening and ring-closing repeating reaction was carried out in a benzene solution by light irradiation.

The glass transition temperatures of (A) and (B) were measured separately and were about 115 ° C and 125 ° C, respectively. The reversible reaction by light was observed to change the extinction coefficient (ε) of (B), but after repeating 30 times or more,
The retention rate of 80%, which is the standard, can be sufficiently achieved.
The influence of side reactions such as isomerization observed in the stilbene type low molecular weight system was small and the cycle life was excellent.

Although the solution of (B) was heated at 80 ° C., after 20 hours,
It was confirmed that the structure (infrared, NMR spectrum) and the extinction coefficient did not change and were extremely stable. This product was coated on a glass plate with a spin coater, and after forming a thin film, it was heated at 80 ° C. in the same air for 20 hours, but no change was observed and excellent thermal stability was exhibited.

For comparison, a similar low molecular weight compound 1,2-
When the photoreversible reaction was repeated for a benzene solution of di (2,3,5-trimethylthienyl) -2-butene, the extinction coefficient of the ring-closing system decreased to 80% or less of the initial value after several times.

(Example 2) A polymer of 2,3-di (2,5-dimethylfuryl) butadiene was synthesized in the same manner as in Example 1. Molecular weight is about 15
It was 000 (GPC). Also, by photoirradiation with wavelengths of 313 nm and 400 nm, a photochromic reversible reaction was performed, and similarly good results such as thermal stability and repeated life were confirmed.

Claims (3)

[Claims] 1. A polymer photochromic compound having a molecular weight of 5,000 or more, which is composed of a polymer containing the cis-1,4 structural unit represented by the general formula [I] as an essential component.
(However, R _{1 to} R ₄ represent a hydrogen atom or an alkyl group, X,
Y represents an aromatic ring or a heteroaromatic ring represented by the following general formula [a] or [b]. ) (However, R ₅ represents an alkyl group, R ₆ and R ₇ represent a hydrogen atom or an alkyl group, Z represents S, O, N—R ₈ , Se, and R ₈ represents a hydrogen atom or an alkyl group.) (However, R ₉ and R ₁₃ are alkyl groups, and R _{10 to} R ₁₂ are hydrogen atoms or alkyl groups.) 2. The polymer photochromic compound according to claim 1, which has a glass transition temperature of 60 ° C. or higher. 3. A structural unit represented by the general formula [I] is obtained by polymerization of a diene compound represented by the following general formula [II], wherein (1) or (2). The high-molecular photochromic compound according to the item. (However, R _{1 to} R ₄ and X and Y are the same as in formula [I])