JPH0515039B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a cellulose-derived polyol derivative, and more specifically, to a cellulose-derived polyol derivative containing a cellulose-derived polyol derivative obtained by ring-opening, reducing, and cyanoethylating cellulose. The present invention relates to a highly dielectric composition.

In recent years, highly dielectric materials have been used in various fields such as electroluminescence and capacitors. In particular, electroluminescence, which produces luminescence when an alternating current electric field is applied to a layer formed by dispersing a compound with luminescent ability such as zinc sulfide in a dielectric material, differs from conventional point luminescence and line luminescence. ,
It is essentially a surface-emitting device, and its usefulness as a type of light-emitting display is being reconsidered.

For example, applications have already been made to backlights for liquid crystal displays, backlights for automobile dashboards, electrostatic erase lights for copying machines, and other thin displays, and further applications are expected in many directions.

Among these surface-emitting technologies, organic dispersion electroluminescence type light-emitting devices are expected to be developed with even higher performance because they are relatively inexpensive, lightweight, and flexible. .

(Problems to be Solved by the Invention) By the way, the main function required of a surface light emitter is particularly high brightness. Generally, in order to increase the brightness of electroluminescence, it is effective to use a high-performance light emitter and to use a dielectric material with a high dielectric constant as a dispersion medium for the light emitter. Regarding the fact that the brightness of electroluminescence can be improved by using a material with a high dielectric constant, see, for example, Journal of Optical Society of America 42.
It is also mentioned in Volume 850 (1952).

Dielectric materials currently used in the production of organic dispersed electroluminescent devices include cyanoethylated cellulose (dielectric constant = 13-15), vinylidene fluoride (dielectric constant = 7-8), and vinylidene fluoride copolymer (dielectric constant = 7-8). 7-10), epoxy resin (4-5)
are widely used, but all of them have low dielectric constants and therefore have low brightness when used as electroluminescent elements. Among these, when cyanoethylated cellulose is made into a film, it has poor transparency, adhesiveness, and flexibility, and particularly has problems with adhesion to electrodes. In order to improve this adhesiveness, there is a method of mixing cyanoethylated sutucarose, but in any case, almost no improvement in the dielectric constant is observed. In addition, fluorine-based polymers have low dielectric constants and weak adhesive properties, and although attempts have been made to improve this by copolymerization, this is not sufficient. Furthermore, although epoxy resin has strong adhesive strength, it has poor flexibility and has an extremely low dielectric constant.

(Means and effects for solving the problems) As a result of intensive research in order to solve the above problems, the present inventors discovered that after ring-opening and reduction of at least a part of the pyranose rings of cellulose, cyanoethyl The inventors have discovered that a cellulose-derived polyol derivative obtained by chemical conversion has a significantly higher dielectric constant than conventional substances, and have arrived at the present invention. That is, in the present invention, at least a part of the pyranose rings constituting the cellulose molecule is opened, and the resulting reducible group is reduced to form the corresponding alcohol, and then
The present invention relates to a composition comprising a cyanoethylated cellulose-derived polyol derivative and a substance having compatibility with the substance, and a light-emitting device using the composition.

The applicant has filed a separate patent application for the cellulose-derived polyol derivative used in the present invention on May 24, 1980.

First, an example of a method for synthesizing a cellulose-derived polyol derivative will be described, but the method is not limited thereto.

First, the opening of the pyranol ring is performed in a neutral to weakly acidic solution in which periodic acid or a periodate salt is dissolved in water or other solvent. Potassium salts and sodium salts are commercially available as periodate salts, but since potassium salts are neutral to weakly acidic and poorly soluble, it is preferable to use sodium salts. In order to prevent side reactions such as peroxidation, this reaction is preferably carried out at a low temperature while shielding from light, and a buffer is used if necessary.

Further, the reduction can be carried out by catalytic reduction, sodium borohydride, or the like. When using sodium borohydride, the product forms a stable compound with boron, so it must be purified by passing it through an ion exchange resin or by acetylation and deacetylation after isolation. be.

Cyanoethylation can then be carried out by Michael addition of acrylonitrile using an alkali catalyst.

The ring-opening rate of the ring-opened product, which is an intermediate product in the present invention, can be determined by quantifying the aldehyde group at the cleavage site caused by ring-opening by the hydroxylamine method.

The measurement principle of the hydroxylamine method is shown by the following equation.

The measured values in the test using the reaction of this formula are: a = Titration of the standard hydrochloric acid solution (ml) b = Titration of the standard hydrochloric acid solution in a blank test (ml) N = Normality of the standard hydrochloric acid solution S = Weight of the sample ( mg), then weight of carbonyl group (%) W=
28.01×(ba)×N/S×100 At this time, the ring opening rate α (%) is α=162.14×W/100/2×28.01+2.016×W/×100×
given in 100.

Next, in the present invention, the polymer constituting the highly dielectric composition formed by mixing the above-mentioned cellulose derivative and a compatible polymer, regardless of whether or not it contains a cyanoethyl group, Examples of polymers that do not have a cyanoethyl group include cellulose derivatives, polyvinyl alcohol derivatives, polyacrylic esters, polymethacrylic esters, polyfumaric esters, and acrylates and styrenes. Polymers, methacrylate-styrene copolymers, etc. are mentioned, and examples of polymers having a cyanoethyl group include the above-mentioned polymers not having a cyanoethyl group, as well as cellulose, polyvinyl alcohol, and cyanoethylated polysaccharides. Examples include, but are not limited to, polymers.

The highly dielectric composition of the present invention also includes the above-mentioned polymer which does not contain a cyanoethyl group, or cellulose which becomes compatible with the above-mentioned cellulose-derived polyol derivative by cyanoethylation.
It can also be produced by mixing polyvinyl alcohol, pullulan, etc. with an alcohol obtained by opening and reducing at least some of the pyranose rings constituting cellulose, and then cyanoethylating the mixture.

The cellulose-derived polyol derivative (at least a portion of the pyranose rings constituting cellulose is ring-opened, reduced, and then cyanoethylated), which is the main component of the present invention, provides excellent dielectric properties, but the shape of the material Depending on the ring-opening and reduction conditions, it becomes wax-like or syrup-like. In particular, those exhibiting a syrupy shape cannot be used alone to form a film. In this case, by blending a substance that is compatible with this cellulose derivative and has film-forming properties, a composition that has both excellent dielectric properties and excellent film-forming properties can be provided. I can do it. Further, since the organic dispersion type electroluminescent device (electroluminescent device) having a mixture of the highly dielectric composition of the present invention and an electroluminescent material as a light emitting layer has a high initial brightness, it is necessary to obtain normal brightness. In this case, the excitation conditions for light emission may be mild, and therefore the device has a long lifetime, making it possible to obtain a practically useful device.

(Example) The present invention will be specifically explained below using Examples, but these are only examples of the present invention, and the present invention is not limited to the combination thereof. The dielectric constant is measured at 1000 Hz Reference example 1 Add 40 g of cellulose with a degree of polymerization of about 300 and 800 ml of a 0.5 mol/sodium metaiodate aqueous solution to a flask equipped with a stirrer, stir at room temperature for 90 hours, filter the precipitate, and wash with water. By repeating this process, 59.4 g of undried ring-opened cellulose (40% moisture) was obtained.

A portion of this was taken out and dried in vacuum, and then the carbonyl group was quantified using the hydroxylamine method.The carbonyl group was 31.4%, that is, the ring opening rate was 90.0.
It was %.

Obtained undried cellulose (water content 40%) 50
g, Raney nickel catalyst (W-7) 15ml and water
Pour 400ml into 1 autoclave and increase the hydrogen pressure.
When catalytic reduction was carried out at 80°C for 2.5 hours under a setting of 30Kg/cm ² , 0.33mol of hydrogen was absorbed. The reaction solution was centrifuged to collect the supernatant, which was filtered to remove the catalyst. The water in the solution was distilled off under reduced pressure using a rotary evaporator, and the residue was vacuum-dried at 40°C, yielding 22.0 g of reduced product. Obtained.

20.0 g of this reduced product, 17.7 g of 5% aqueous sodium hydroxide solution, and 200 ml of acrylonitrile were placed in a flask equipped with a stirrer, and reaction was carried out at 55° C. for 2.5 hours while stirring. After the reaction was completed, acetic acid was added to make the reaction system acidic, and acrylonitrile was distilled off under reduced pressure using a rotary evaporator. Add pure water to the residue to precipitate the product, wash thoroughly with water, dissolve in acetone, pass through a 1μ membrane filter,
It was poured into a large amount of pure water and reprecipitated. Then the precipitate is 40
After vacuum drying at ℃, 31.3 g of syrupy cyanoethylated product was obtained.

The physical properties of the obtained cyanoethylated product were measured and the results were as follows.

Shape: Opening rate of brown transparent syrupy pyranose ring: = 90.0% Dielectric constant: ε = 41 (measured at 1000 Hz) Dielectric loss tangent: tan δ = 0.18 (same as above) Reference example 2 An open ring prepared in the same manner as Reference example 1 20 g of ringed undried cellulose (water content 40%), 400 ml of water, and 7 g of sodium borohydride were mixed into a flask equipped with a stirrer, and stirring was continued at room temperature overnight. After the reaction was completed, acetic acid was added to decompose excess sodium borohydride and the reaction solution was made acidic, followed by cation exchange resin (Dowex = 50, manufactured by Dow Chemical Company), anion exchange resin (Imberlite IRA-410, (manufactured by Rohm and Haas) to remove metal ions and boron ions and purify it. The solvent of the purified reaction solution was distilled off under reduced pressure using a rotary evaporator.
6.3 g of reduced product was obtained.

6 g of the obtained reduced product, 5.3 g of 5.0% aqueous sodium hydroxide solution, and 60 ml of acrylonitrile were placed in a flask equipped with a stirrer, and reaction was carried out at 55° C. for 25 hours while stirring. After the reaction was completed, acetic acid was added to make the reaction system acidic, and then acrylonitrile was distilled off under reduced pressure using a rotary evaporator. Add water to the residue and after washing with water, dissolve the product in acetone and dilute with 1μ
After removing insoluble materials using a membrane filter, the mixture was poured into a large amount of pure water and reprecipitated.

Dry the precipitate at 40℃ in a vacuum dryer to give 10.1g.
A cyanoethylated product was obtained.

The results of measuring various properties of the obtained cyanoethylated product were as follows.

Shape: Colorless transparent solid Melting point: 98°C Ring opening rate of pyranose ring: 90.0% Dielectric constant: ε = 31 (measured at 1000Hz) Dielectric loss tangent: tan δ = 0.009 (same as above) Example 1 Produced by the method of Reference Example 1 A composition of 5 g of cellulose-derived polyol derivative (ε=41) and 10 g of cyanoethylated dextran (ε=18) was dissolved and mixed in a mixed solvent of acetone:DMF=9:1 to make a 30% solution, and a part of it was dissolved. After casting on a glass plate and gradually evaporating the solvent at room temperature to form a film, the solvent was removed at 60 to 80°C and 10 ^-1 to 10 ^-2 mmHg for 5 hours.

The obtained film was light in color, transparent, and highly flexible. The dielectric constant of this film was ε=22.

The cellulose-derived polyol derivative (ε=41) used to make this film has an extremely high dielectric constant, but it has a syrupy shape, so it cannot be made into a film, and it is difficult to make a film using only cyanoethylated dextran. However, the film obtained by blending as in this example had an excellent dielectric constant, was light in color and transparent, and was highly flexible and highly practical.

Example 2 DMF was added to the same composition as in Example 1 as a dielectric material to make a 30% solution, and a zinc sulfide luminescent material for electroluminescent devices was added at a weight ratio of 1:1 to the solid content of the composition. The mixture was mixed and thoroughly dispersed using a homomixer. This dispersion was coated on aluminum foil to a thickness of 50μ by screen printing, and the temperature was kept at 60°C for a day and a night.
It was vacuum dried. A polyvinylidene fluoride film made of polyvinylidene fluoride was bonded to the polyester film so that the vapor-deposited surface of a transparent conductive film in which indium oxide was vapor-deposited was in contact with the polyester film, electrode terminals were attached to the aluminum foil and the transparent conductive film, respectively, and finally an adhesive layer was applied. An electroluminescent device was fabricated by sandwiching them between moisture-proof films and integrating them by thermocompression.

When a voltage of 100V and 60Hz was applied to both terminals of this element, it emitted strong light, and when the luminance was measured,
16Cd/m ² , making it an excellent light-emitting device.

Example 3 10 g of the cellulose-derived polyol derivative (ε=41) prepared by the method of Reference Example 1 and 10 g of cyanoethylated pullulan (ε=14) were mixed in acetone:DMF.
= Dissolved in a 9:1 mixed solvent, and the rest were as in Example 1.
A composition film was prepared in the same manner as above. The dielectric constant of this film was ε=24. The cellulose-derived polyol derivative used to make this film is syrup-like and cannot be made into a film by itself.Furthermore, although cyanoethylated pullulan has excellent heat resistance, the film made by itself is not flexible. Although poor, the film made of the composition of this example had an excellent dielectric constant, and was a highly practical film with excellent transparency, flexibility, and heat resistance.

Example 4 An electroluminescent device was produced in the same manner as in Example 2, except that the same composition as in Example 3 was used as a dielectric.

When a voltage of 100V and 60Hz was applied to both terminals of this element, it emitted strong light, and when the luminance was measured,
17Cd/m ² , making it an excellent light-emitting device.

Example 5 10 g of the cellulose-derived polyol derivative (ε=31) prepared by the method of Example 2 and 10 g of cyanoethylated PVA (ε=14) were mixed in acetone:DMF=
A composition film was prepared in the same manner as in Example 1 except that the mixture was dissolved in a 9:1 mixed solvent.

The dielectric constant of this film was ε=23.

The cellulose-derived polyol derivative used in this film is a colorless and transparent solid with a melting point of 98°C, but its adhesion is not necessarily sufficient, and cyanoethylated PVA has excellent adhesion, flexibility, and transparency, and it forms a film. However, the film of this example has an excellent dielectric constant and has excellent physical properties such as transparency, adhesiveness, and flexibility. It was a highly practical film.

Example 6 An electroluminescent device was produced in the same manner as in Example 2 except that the same composition as in Example 5 was used as the dielectric. When a voltage of 100 V and 60 Hz was applied to both terminals of this device, it emitted strong light. However, when the luminance was measured, it was 15 Cd/m ² , indicating that it was an excellent light-emitting device.

Example 7 A ring element obtained by ring-opening and reducing a part of the pyranose rings constituting cellulose in the same manner as in Example 1
10 g of cellulose were subjected to cyanoethylation, purification, and drying under the same conditions as in Reference Example 1. A part of the obtained mixture was dissolved in a mixed solvent in the same manner as in Example 1, cast, and dried to produce a film.

The obtained film was colorless, transparent, and highly flexible. Further, the dielectric constant of this film was ε=20.

This film is a film-like material in which only cellulose is cyanoethylated (the dielectric constant is usually ε = 13 ~
15), it had superior dielectric constant and transparency.

Example 8 An electroluminescent device was produced in the same manner as in Example 2 using the cyanoethylated mixture obtained in Example 7.

When a voltage of 100 V and 60 Hz was applied to both terminals of this element, it emitted light quite strongly, and when the luminance was measured, it was 10 Cd/m ² .

Comparative Example 1 An electroluminescent device was produced in the same manner as in Example 2, except that the same cyanoethylated polyvinyl alcohol (ε=14) used in Example 5 was used as the dielectric. When a voltage of 100V and 60Hz was applied to both terminals of this element, the luminance was quite weak and the luminance was 5Cd/
It was ^m2 .

(Effects) As described above, the dielectric composition of the present invention has excellent dielectric properties, and when formed into a film, has excellent transparency, flexibility, adhesiveness, heat resistance, etc. An organic dispersion type electroluminescent device having a light-emitting layer made of a mixture of a composition and an electroluminescent material had extremely high brightness and was highly practical.

Claims (1)

[Scope of Claims] 1. A cellulose-derived polyol derivative obtained by cyanoethylating an alcohol obtained by opening at least some of the pyranose rings constituting cellulose and reducing the resulting functional groups, and said substance. A highly dielectric composition comprising a compatible polymer. 2. A cellulose-derived polyol derivative obtained by cyanoethylating an alcohol obtained by opening at least some of the pyranose rings constituting cellulose and reducing the resulting functional groups, and polymerization that is compatible with the substance. A dispersion type electroluminescent device whose light emitting layer is a mixture of a substance and an electroluminescent substance.