JPH03215465A - Purification of cyanoethylated polyol - Google Patents

Abstract

PURPOSE:To obtain the title compound as a binder for EL elements in high purity with no residual unreacted hydroxyl group by esterification of the hydroxyl groups in a cyanoethylated polyol with an organic acid anhydride followed by removing the product with an aqueous alkali solution. CONSTITUTION:The hydroxyl groups in a cyanoethylated polyol formed by cyanoethylation of a 2-12C polyol is put to esterification with an organic acid anhydride (e.g. phthalic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride), and the resulting carboxylic acid compound is removed using an aqueous alkali solution, thus accomplishing the objective purification. In the above reaction, e.g. pyridine is used as catalyst, and e.g. acetone as solvent. The reaction is carried out at 30-160 (pref. 60-100) deg.C. It is preferable that the amount of the organic acid anhydride to be used be 1.0-5.0mol per mol of the unreacted hydroxyl group.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention relates to a method for purifying cyanoethylated polyol, which is a highly dielectric material, and particularly relates to a method for purifying cyanoethylated polyol, which is a highly dielectric material, and particularly relates to a method for purifying a cyanoethylated polyol, which is obtained by esterifying the hydroxyl group in the cyanoethylated polyol with an acid anhydride. The present invention relates to a method for purifying highly cyanoethylated polyols by washing and removing carboxylic acid compounds with an alkaline aqueous solution. Such high purity cyanoethylated polyol is dispersed type E
It is suitable as a binder for 1-1 elements.

<Prior art> Dispersion type El elements generally use a metal foil such as aluminum foil as a back electrode, and on this back electrode, inorganic high dielectric powder such as titanium oxide or barium titanate is dispersed in an organic high dielectric binder. A reflective insulator layer is formed, and on top of that a light emitting layer is formed by dispersing phosphor powder such as zinc sulfide in an organic high dielectric binder, and finally a transparent layer such as ITO (a mixture of indium oxide and tin oxide) is formed. It has a structure in which an electrode is installed as a counter electrode, and the phosphor emits light by applying an alternating current voltage between both electrodes.

Note that a dispersion type E1 element in which only a light emitting layer is sandwiched between a back electrode and a transparent electrode is also used.

Currently, these organic high dielectric binders are compositions comprising at least one cyanoethylated polymer or cyanoethylated polyol and a cyanoethylated polymer compatible therewith. (Patent Application Publication 15937/1982) The above cyanoethylated polyol can be obtained by reacting a polyol with acrylonitrile in the presence of an alkali according to the synthesis method described in U.S. Pat. No. 3,161,539, U.S. Pat. I can do it.

For example, about 0.2 mol of sodium hydroxide per hydroxyl group in a polyol molecule is added as a 10% aqueous solution to obtain an alkaline solution, and about 15 times the molar amount of acrylonitrile is added to the solution with stirring at a reaction temperature of 35 to 45°C for 30 to 60 minutes. drip. After stirring at the same temperature for about 2 hours, the resulting cyanoethylated polyol was extracted with an appropriate amount of organic solvent tS (chloroform, ethyl acetate, etc.), and washed with water, 1N acetic acid (or 1N hydrochloric acid), and water in this order. After drying over anhydrous calcium sulfate, the organic solvent was distilled off under reduced pressure, and further heated at 100°C and 0.5°C.
Maintain at 5 mH (l) for 3-5 hours to completely remove volatiles.

The cyanoethylated polyol synthesized by this method has a cyanoethylation rate of 80% or more and is a viscous liquid, but it is difficult to produce a highly pure cyanoethylated polyol that is completely free of unreacted substances by synthesis. there were.

Problems to be Solved by the Invention At present, all EL devices using binders containing such cyanoethylated polyols have short lifetimes of light emission. This is because the phosphor in the binder deteriorates under the influence of moisture when an electric field is applied. Although the mechanism of this deterioration is not clear, it is thought to be due to the ether bond of the cyanoethylated polyol, and the presence of unreacted residual hydroxyl groups is considered to be a major cause of moisture adsorption.

For this reason, E [unreacted residual water as a binder of the element
It was desired to provide a high purity cyanoethylated polyol that does not have 12 groups.

<Means for Solving the Problems> As a result of intensive studies to solve the above problems, the present inventors found that in the purification of cyanoethylated polyols having 2 to 12 carbon atoms, water 12
It has been found that a highly pure cyanoethylated polyol having no residual hydroxyl groups can be obtained by subjecting the group to an esterification reaction with an organic acid anhydride and removing the resulting carboxylic acid compound with an alkaline aqueous solution.

The cyanoethylated polyol according to the present invention has 2 to 1 carbon atoms.
This is a cyanoethylated polyol of No. 2. Polyols having 2 to 12 carbon atoms are polyhydric alcohols having two or more hydroxyl groups, and may be linear or branched, and may have an ether bond in the molecule or be cyclic. It may also have a monotel bond. Also included are monosaccharides, monomethylated or ethylated simples, disaccharides, and monomethylated or ethylated disaccharides.

Cyanoethylated polyols having 2 to 12 carbon atoms generally have a high dielectric constant, are liquid or waxy, and are suitably used as binders.

A cyanoethylated polyol can be obtained by cyanoethylating such a polyol. The cyanoethylated polyol is cyanoethylated xylitol. Cyanoethylated sorbitol, cyanoethylated mannitol. Cyanoethylated diglycerin, cyanoethylated pentaerythritol, cyanoethylated trimethylolpropane,
Examples include cyanoethylated inositol, cyanoethylated methylglucose, and cyanoethylated sugar syrup.

In the cyanoethylated polyol, it is difficult to completely cyanoethylate 1!38% of water, and a cyanoethylated product having a hydroxyl group remains as an impurity.

In the present invention, the hydroxyl group in the cyanoethylated polyol is subjected to an esterification reaction with an organic acid anhydride, and the produced carboxylic acid compound is removed with an aqueous alkaline solution.

As the esterifying agent, ays anhydride is used.

For example, phthalic anhydride. Trimellitic anhydride, pyromellitic anhydride, penzophenonetetracarboxylic anhydride, maleic anhydride, tetrahydrophthalic anhydride, 4-methyl-tetrahydrophthalic anhydride, 3-methyl-tetrahydrophthalic anhydride. Nadic anhydride, methyl nadic anhydride. Succinic anhydride. Examples include hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, and 3-methylhexahydrophthalic anhydride.

As a catalyst, pyridine, dimethylbenzylamine, 1
, 8-diazabisic acid [5,4,OJ-bases such as 7-undecene (hereinafter referred to as DBtJ), p-toluenesulfonic acid. Acids such as sulfuric acid and salts such as sodium acetate and zinc chloride can be used.

Examples of the reaction solvent include acetone. Acetonitrile, N,N'-dimethylacetamide, dimethylsulfoxide, N,N'-dimethylformamide<DMF)
, pyridine, etc., but the reaction proceeds even in a solvent-free system.

Although it depends on the cyanoethylation substitution rate of the cyanoethylated polyol, the organic acid anhydride used is preferably 1.0 to 5.0 moles per mole of unreacted hydroxyl groups, and the catalyst used is preferably 1.0 to 5.0 moles per mole of unreacted hydroxyl groups. 0.01 to 0.05 mol is preferable. The reaction temperature is generally 30-160°C, preferably 60-100°C, and the reaction time is -1-48°C.
The process can be carried out for a period of time, preferably from 2 to 24 hours.

In this way, unreacted hydroxyl groups in the cyanoethylated polyol are converted into esters with carboxylic acids, and all cyanoethylated polyols having hydroxyl groups become compounds having carboxylic acids. If the viscosity is high after the reaction, it is diluted by adding a solvent such as dichloromethane, an aqueous alkali solution is added, and washing is repeated several times in order to dissolve the cyanoethylated polyol having carboxylic acid in the aqueous layer. The alkaline aqueous solution used at this time is sodium carbonate. Sodium hydroxide. Those capable of forming salts with carboxylic acids, such as sodium hydrogen carbonate, potassium carbonate, potassium hydroxide, and potassium hydrogen carbonate, can be used, and are used in an amount equivalent to or more per anhydride used for esterification.

Thereafter, the reaction solution is washed with water and neutralized. Alkali washing and water washing are carried out by commonly used methods such as extraction and decanting. The purified cyanoethylated polyol from which the carboxylic acid compound has been removed in this manner can be obtained by dehydrating with anhydrous magnesium sulfate or the like and then removing the solvent. This purified cyanoethylated polyol is 995% or more, preferably 998%
% or more.

Next, the high purity cyanoethylated polyol contains at least 1
It can be used alone or in combination with a cyanoethylated polymer that is compatible with it as an organic high dielectric binder for dispersed EL devices. When used in combination, the cyanoethyl polyol is contained preferably at least 5% by weight, more preferably at least 10% by weight.

As a cyanoethylated polymer, the dielectric constant is 10 or more (1κH
For example, cyanoethylated Bobal. Cyanoethylated ethylene-vinylalyl copolymer, cyanoethylated bullulan, cyanoethylated cellulose, cyanoethylated hydroxyethylcellulose. Examples include 7-noethylated starch.

A dispersion type E element using the high purity cyanoethylated polyol of the present invention or a composition thereof as a binder can be produced by a known method. For example, a binder is dissolved in a solvent to prepare a 5 to 50% by weight solution, and 100 parts by weight of the binder is mixed with 50 to 50 parts by weight of the inorganic high dielectric powder.
900 parts by weight were dispersed and mixed to obtain a uniform slurry. This is applied to a metal electrode by a general method such as screen printing or casting, and the solvent is evaporated and dried to form a reflective insulator layer. On the other hand, in the binder solution, 50 to 900 parts of the phosphor is added to 100 parts by weight of the binder.
Disperse and mix the parts by weight to obtain a uniform slurry. This is applied onto the reflective insulator layer in the same manner as above, and the solvent is evaporated and dried to form a light-emitting layer. Next, after attaching electrode terminals to the glass or transparent electrode film coated with the obtained coating film and transparent electrode, the conductive surfaces of the coating film and the transparent electrode are brought into contact with each other, and these are integrated to form a composite structure. A distributed EL element is obtained.

The phosphor used here may be any phosphor that is normally used for EL devices, such as zinc sulfide, and is normally used for dispersion type EL devices.

Examples of the solvent used to prepare the binder solution include DMF, N,N'-dimethylacetamide.
Examples include dimethyl sulfoxide, acetone, methyl ethyl ketone, and acetonitrile.

As the electrode, any electrode that is normally used in EL elements can be used, but for the back electrode, for example, one with a thickness of about 50 mm to
On the other hand, as a transparent electrode, for example, ITOI can be used on one side of a polyester film with a thickness of about 75 to 125 p. One example is one in which conductivity is imparted by arranging L.

<Effects of the Invention> The present invention involves esterifying a cyanoethylated polyol containing 119% water in a cyanoethylated polyol having 2 to 12 carbon atoms with an organic acid anhydride, and removing the resulting carboxylic acid compound with an aqueous alkali solution. This is a method for purifying cyanoethylated polyols, and it is possible to completely remove cyanoethylated polyols having hydroxyl groups. Therefore, this purified cyanoethylated polyol can be used as a dispersed E
When used as a binder for the light-emitting layer or reflective insulator layer of an EL device, the influence of moisture can be reduced, making it possible to obtain a dispersion-type EL device with a miserable and long brightness life.

The present invention will be explained below based on Examples.

Example 1 Stirring device. 100d 3 with thermometer and cooling pipe attached
44.5 g of cyanoethylated sweet potato loin (cyanoethylation substitution rate 96.1%) was placed in a turophore flask, and 8.9 g of 4-methyl-hexahydrophthalic anhydride and D B tJ O. 53 g was added and stirred at about 60° C. for 24 hours to carry out the reaction. After the reaction, dichloromethane 50
d, and washed four times with a 2% aqueous sodium monocarbonate solution. 50 d of dichloromethane was added to the solution to dilute it, and this was washed four times with pure water. The dichloromethane layer was separated, and after dehydration with anhydrous magnesium sulfate, the solvent was removed under reduced pressure to obtain high purity cyanoethylated sweet potato loin. This cyanoethylation substitution rate was 999%.

A mixture of 30 g of this cyanoethylated sweet potato loin and cyanoethylated bull run 309 was dissolved in DMF,
% binder solution was prepared. 100 g of this solution was kneaded with 139.29 powder of barium titanate (BT-100M, manufactured by Fuji Titanium Co., Ltd.) as an inorganic high dielectric material to form a uniform slurry, which was coated on an aluminum plate and dried to give a film thickness of 30 mm. An insulator layer was formed.

On the other hand, powder 98.49 of zinc sulfide (Sylvania 723 manufactured by GTE Products Co., Ltd.) as a phosphor was cross-dispersed in the above binder solution ioog to form a uniform slurry, and the slurry was coated on the reflective insulator layer to form a light-emitting layer with a dry film thickness of 55IIIR. was formed.

The laminate created by the above series of steps is 10c
It was cut into a size of m x 10 cm, a lead terminal was attached, and then dried.

On the other hand, a transparent conductive film with an ITO film formed on one side of polyethylene terephthalate was also used in a 10 cm
After cutting the film into a size of m, and attaching lead terminals, the light-emitting layer of the above-described laminate and the ITO surface of the transparent conductive film were heated and laminated. Thereafter, a nylon film was laminated on the surface of the back electrode and the surface of the front electrode, and the entire periphery was further surrounded and sealed with a polytrifluorochloroethylene film.

IOOV-400Hz between both electrodes of the obtained EL element
Table 1 shows the luminance when an alternating current electric field of 100% was applied, and the luminance half-life when continuously lit in an atmosphere of 23° C. and 50% relative humidity (R.H.).

The cyanoethylation substitution rate was calculated from the residual hydroxyl value measured by a conventional acetic anhydride monopyridine method.

Example 2 Cyanoethylated xylitol (cyanoethylation substitution rate 9
7. A purified product (cyanoethylation substitution rate ioo.o%) and a dispersed EL device were obtained in the same manner as in Example 1, except that the raw material was 0%).

The obtained dispersion type EL device was subjected to the same test as in Example 1. The results are shown in Table 1.

Example 3 Cyanoethylated sorbitol (cyanoethylation substitution rate 9
A purified product (cyanoethylation substitution ratio 100%) was prepared in the same manner as in Example 1 except that 4-methyl-tetrahydrophthalic anhydride was used as the esterifying agent.
0%) and a dispersion type E element were obtained.

The dispersion type EL device created in the above manner was subjected to the same test as in Example 1. The results are shown in Table 1.

Example 4 Cyanoethylated diglycerin (cyanoethylation substitution rate 9
A purified product (cyanoethylation substitution rate: 999%) and a dispersed El element were obtained in the same manner as in Example 3, except that 69%) was used as the raw material.

The obtained dispersion type E1 element was subjected to the same test as in Example 1. The results are shown in Table 1.

Comparative example 1 Cyanoethylated sweet potato loin (cyanoethylation substitution rate 9
A dispersion type EL device was obtained in the same manner as in Example 1, except that 6.1%) was used without purification.

Comparative Example 2 Cyanoethylated xylitol (cyanoethylation substitution rate 9
A dispersion type EL element was obtained in the same manner as in Example 1, except that 1.0%) was used without purification.

Comparative Example 3 Cyanoethylated sorbitol (cyanoethylation substitution rate 9
A dispersion type EL device was obtained in the same manner as in Example 1, except that 11%) was used without purification.

Hiroki'' [1A Cyanoethylated diglycerin《Cyano T-thylation substitution rate 9
A dispersion type EL device was obtained in the same manner as in Example 1, except that 69%) was used without purification.

The dispersion type E1 elements obtained in Comparative Examples 1 to 4 were subjected to the same test as in Example 1. The results are summarized in Table 1.

Table 1 From Table 1, a dispersion type E1 element (
It can be seen that the luminance half-life time of Examples 1 to 4) is much longer than that of the EL elements using unpurified cyanoethylated polyol (Comparative Examples 1 to 4).

Procedural amendment March 2nd, 1990 1. Display of incidents 1990 Patent Application No. 5596 2 name of invention Method for purifying cyanoethylated polyol 3. person who makes corrections Relationship with the incident

Claims (1)

[Claims] (1) In the purification of a cyanoethylated polyol having 2 to 12 carbon atoms, the hydroxyl group in the cyanoethylated polyol is subjected to an esterification reaction with an organic acid anhydride, and the resulting carboxylic acid compound is removed with an aqueous alkaline solution. A method for purifying cyanoethylated polyol.