JPS6347206B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel polymeric dielectric materials with extremely high dielectric constants.

Modification through various chemical reactions is carried out to change the properties of polymeric substances or to impart new functions. Cyanoethylation using acrylonitrile is one of them, and the most typical example is cyanoethylated cellulose. Cyanoethylated cellulose is endowed with solubility in various solvents and a high dielectric constant, so it is used as a binder for the luminescent material of dispersed electroluminescence (EL) elements, and is also considered for use in capacitor films, etc. It is being

The present inventors carried out cyanoethylation of hydroxyethyl methacrylate polymer, and the newly obtained cyanoethylated hydroxyethyl methacrylate polymer has an extremely high dielectric constant even compared to cyanoethyl cellulose. It has been found that this material can be a dielectric material with a high dielectric constant.

The present invention will be explained in detail below.

The hydroxyethyl methacrylate polymer used in the present invention is usually obtained by solution polymerizing hydroxyethyl methacrylate monomer in ethyl alcohol using a peroxide such as azobisisobutyronitrile (ABIN) as a catalyst. It will be done. Any degree of polymerization can be obtained using a chain transfer agent, but it is usually controlled using acetone, mercaptan, etc. Hydrooxyethyl methacrylate polymer is soluble in ethyl alcohol, so the polymer is obtained as an ethyl alcohol solution, and the obtained polymer is reprecipitated several times to remove residual monomers, catalyst residues, etc. after polymerization. The process is repeated, and finally, water and the solvent are removed by vacuum drying to obtain a hydroxyethyl methacrylate polymer represented by the general formula (A) below.

The cyanoethylated hydroxyethyl methacrylate polymer, which is the main constituent material of the present invention, is a polymer of formula (A) in which some or all of the hydrogen atoms in the alcohol groups have been replaced with cyanoethyl groups (-CH ₂ CH ₂ CN). . The degree of cyanoethylation varies depending on the intended use, such as solubility in solvents, dielectric loss, and other properties, but it is preferable that at least 50% of the OH groups are cyanoethylated, especially for dielectric materials with high dielectric constants. In this case, those with 80% or more cyanoethylation are more preferable.

In the cyanoethylation reaction, acetone is added to the hydroxyethyl methacrylate polymer as a solvent.
Furthermore, the raw material acrylonitrile is added, and a caustic alkali aqueous solution is used as a catalyst.
It is preferably carried out at a temperature of 60°C or lower. In particular, if the reaction temperature is excessively raised in the presence of an excess of acrylonitrile, a low polymer of acrylonitrile may be produced, which may significantly impair the thermal stability of the product, so care must be taken.

The hydroxyethyl methacrylate polymer that has been cyanoethylated in this range is thermoplastic, and the film has an extremely high dielectric constant. As is clear from the later examples, for example, a solution with a solution viscosity η _ioh =0.1093 dl/g and a degree of cyanoethylation of alcohol groups of about 92.6% exhibits a dielectric constant of about 20 at 1 KHz and 25°C.

Further, the cyanoethylated hydroxyethyl methacrylate polymer of the present invention has a methacrylate skeleton, so it has excellent fluidity during hot melting and also has excellent thermal stability.

Furthermore, it has excellent flexibility, and even when used as a binder for dispersed electroluminescent devices, for example, its resistance to bending and breaking is superior to that of cyanoethylcellulose.

Furthermore, this cyanoethylated hydroxyethyl methacrylate polymer is insoluble in solvents such as water, methanol, and ethanol, but is not soluble in solvents such as acetone, methyl ethyl ketone, dimethyl formamide, dimethyl acetamide, acrylonitrile, etc.
Since it dissolves in solvents such as chloroform, it is possible to form it into a film in the form of a solution of these solvents, and it is also possible to mix it with an inorganic binder such as ZnS.

As described above, the cyanoethylated resin of the present invention takes advantage of its characteristics such as high dielectric constant and processability, and is extremely useful as a high dielectric material used, for example, as a binder for electroluminescence.

EXAMPLES In order to explain the present invention in more detail, an explanation will be given below using examples.

Example 1 50 g of hydroxyethyl methacrylate monomer (hereinafter abbreviated as HEMA) manufactured by Aldrich, 200 g of ethyl alcohol, 1 g of azobisisobutyronitrile (hereinafter abbreviated as ABIN), and 2 g of n-dodecyl mercaptan were thoroughly dissolved and mixed. Polymerization was carried out at 50° C. for 16 hours while vigorously stirring and mixing in a 300 ml glass ampoule. Next, pour the polymerization solution into saturated saline solution,
Precipitate HEMA polymer. The precipitate was redissolved in methanol and reprecipitated in saline several times, and the precipitate was thoroughly washed with water and dried to remove the polymer.
I got 40g. 40 g of the obtained HEMA polymer, 150 g of acrylonitrile, 50 g of acetone, 0.8 g of NaOH,
10 g of H ₂ O was stirred and reacted at 50°C.

The polymerization solution is poured into methanol and stirred to precipitate the cyanoethylated resin.

Next, an acetone solution of this precipitate was poured into water and stirred to perform reprecipitation, and the reprecipitate was dried, and the cyanoethylated hydroxyethyl methacrylate resin was
Obtained 38g. The solution viscosity of the obtained cyanoethylated hydroxyethyl methacrylate resin was η _ioh =0.1093 dl/g at a resin concentration of 4 g/g using dimethylformamide as a solvent.

Next, elemental analysis revealed that the nitrogen content was
It was 7.24wt%, and the degree of cyanoethylation was estimated from this to be 92.6%. The infrared absorption diagram of cyanoethylated hydroxyethyl methacrylate is shown in FIG.

Example 2 The cyanoethylated hydroxyethyl methacrylate resin synthesized in Example 1 was heated at 150°C, 5 kg/
Pressure-press the Al foil onto one side of the resin for 2 minutes at cm ² (gauge pressure) to form one electrode, and deposit Al on the exposed part of the resin surface to form the other electrode. It was used as an electrode. The thickness of the resin was 50μ.

The dielectric constant ε and dielectric loss tan δ of this sample are 1KHz
At 25°C, they were 20.1 and 10.5%, respectively.

As mentioned above, it can be seen that this cyanoethylated hydroxyethyl methacrylate polymer has an extremely large dielectric constant when compared with the dielectric constant of cyanoethyl cellulose, which is usually about 16.

It also has good thermal stability, as there is no discoloration even when pressed at 150°C for 2 minutes.

Furthermore, 100μ of the cyanoethylated hydroxyethyl methacrylate polymer synthesized in Example 1
Even when a thick film was bent 180 degrees by hand, it did not break, but when a 100μ thick cyanoethyl cellulose film was subjected to the same treatment, it broke.

[Brief explanation of the drawing]

FIG. 1 shows an infrared absorption diagram of cyanoethylated hydroxyethyl methacrylate obtained in Example 1.

Claims (1)

[Claims] 1. A dielectric material comprising a cyanoethylated hydroxyethyl methacrylate polymer. 2. The cyanoethylated hydroxyethyl methacrylate polymer contains at least 50% of the alcohol groups of the hydroxyethyl methacrylate polymer.
The dielectric material according to claim 1, wherein the above is cyanoethylated.