JPH0234614B2 - YUKAGISHISEIZOYONOSETSUKOGATAOYOBISOREOSHOSURUYUKAGISHINOSEIHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plaster mold for manufacturing a denture and a method for manufacturing a denture using the plaster mold.

(Prior art and its problems) When making dentures, since each denture has a different shape, if a metal mold is used as a mold,
The price of dentures has become very expensive.

Since plaster molds are easy to make and can be made at low cost, a method of making a denture using a plaster mold is commonly used.

When molding resins that exhibit plasticity at high temperatures, such as polysulfone, polyethersulfone, and polycarbonate, using a plaster mold, it is necessary to raise the temperature of the plaster mold to a high temperature of about 100 to 200°C.
When a plaster mold made of calcium sulfate dihydrate is heated, it changes sequentially from a hemihydrate to an anhydride, but this change causes a decrease in strength and the formation of many fine irregularities on the surface. The surface becomes rough. If a denture is molded using a plaster mold with such a rough surface, plaster will get mixed into the molded denture base, resulting in a denture with a rough surface, and it will take a lot of time and effort to polish the denture. Not only is this necessary, but it also becomes impossible to reproduce the mucosal impression.

(Requirements of the present invention and its effects) The present invention provides a plaster mold for manufacturing dentures that does not have the above-mentioned problems, and a method for manufacturing dentures using the plaster mold.

According to the present invention, a plaster mold for manufacturing a denture has a coating layer of aromatic polyimide formed on the surface thereof, and a denture is manufactured by molding a thermoplastic resin using the plaster mold. law is provided.

The coating layer made of aromatic polyimide is
It can be formed by directly applying a solution (varnish) of aromatic polyimide or aromatic polyamic acid to a plaster mold, and drying and/or heat-treating the applied layer.

The above solution of aromatic polyimide or aromatic polyamic acid (hereinafter both are collectively referred to as aromatic polymer solution) is prepared by mixing an aromatic tetracarboxylic acid or its acid dianhydride and an aromatic diamine in an organic polar solvent. It is a solution of a heat-resistant aromatic polymer soluble in organic solvents obtained by polymerization at a polymerization temperature of ~250°C.

The aromatic polymer solution has a polymerization temperature of 0 to
When the polymerization temperature is 80°C, it becomes an aromatic polyamic acid solution, and when the polymerization temperature is 120 to 250°C, it becomes an aromatic polyimide solution. The aromatic polymer solution has a polymer concentration of about 3 to 40% by weight, especially 5 to 30% by weight.
The rotational viscosity (25°C) is preferably about 0.5 to 1000 poise, preferably 1 to 1000 poise.
500 poise, particularly preferably 10 to 200 poise.

Examples of the aromatic tetracarboxylic acids include biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid, bis(3,4-dicarboxyphenyl)methane, and 2,2-bis(3,4-dicarboxyphenyl). ) Propane, bis(3,4-dicarboxyphenyl) ether, pyromellitic acid, acid dianhydrides thereof, or mixtures thereof.

Examples of the aromatic diamines include 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylthioether, 4,4'-diaminodiphenylmethane, 3, 4'-diaminodiphenylmethane, 4,
Mention may be made of 4'-diaminodiphenylpropane, 4,4'-diaminobenzophenone, o-, m- or p-phenylenediamine, or mixtures thereof.

In this invention, in particular, 3,3′,4,4′-
A fragrance containing 50 mol% or more, especially 60 mol% or more of biphenyltetracarboxylic acid or its acid dianhydride, or 2,3,3',4'-biphenyltetracarboxylic acid or its acid dianhydride group tetracarboxylic acid component, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, m-
or a solution of aromatic polyimide or aromatic polyamic acid obtained by polymerizing an aromatic diamine component such as p-phenylenediamine;
Obtained by polymerizing an aromatic tetracarboxylic acid component consisting of 3',4,4'-biphenyltetracarboxylic acid or its acid dianhydride and pyromellitic acid or its acid dianhydride and the above-mentioned aromatic diamine component. A solution of the aromatic polyamic acid obtained above is suitable in terms of the solubility of the polymer in an organic solvent (storage stability of the solution, etc.), the mechanical strength of the coating layer, the heat resistance, etc.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N
-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,
Amide solvents such as N-diethylacetamide and tetramethylphosphotriamide, or phenol, o-, m- or p-chlorophenol,
Examples include phenolic solvents such as 2-chloro-5-hydroxy-toluene.

The above-mentioned amide solvents are mainly used as solvents for aromatic polyamic acids, and phenolic solvents are mainly used as solvents for aromatic polyimides. Alternatively, an aromatic polyimide obtained from the acid dianhydride and an aromatic diamine is preferable because it may be dissolved in an amide solvent.

There is no particular restriction on the method of applying the aromatic polymer solution, and methods such as applying the solution to the surface of the plaster mold with a brush or spraying the solution onto the surface of the plaster mold can be adopted.

The aromatic polyimide coating layer can generally be easily formed by applying an aromatic polymer solution to a plaster mold and then drying and heating the mold.

In the present invention, after applying an aromatic polymer solution to the surface of a plaster mold, the applied layer is dried at a temperature of about 20 to 200°C under normal pressure or reduced pressure to remove the solvent, and the aromatic polymer solution is When an aromatic polyamic acid solution is used as
Heat treated at a temperature of 400℃, especially 160-300℃,
It is appropriate to completely remove the solvent in the coating layer and to imidize the polyamic acid. Of course, it is also possible to heat the aromatic polymer immediately after applying it.

The plaster mold is preferably dried at a temperature of 100 to 200°C to remove excess moisture prior to applying the aromatic polymer solution.

The plaster mold obtained in this way has a coating layer of aromatic polyimide that has high heat resistance and mechanical strength, so the surface of the plaster mold will not be roughened during the creation of the denture, and the surface can obtain smooth dentures.

The plaster mold of the present invention is suitably used when molding a thermoplastic resin to manufacture a denture.

As the thermoplastic resin, heat-resistant thermoplastic resins such as polysulfone, polyethersulfone, and polycarbonate, which are generally used as resins for making dentures, are preferably used.

The molding method can be carried out in accordance with a method known per se, such as a compression molding method or an injection molding method. For example, a thermoplastic resin is placed on the bottom mold of a split plaster mold, the thermoplastic resin is softened in an atmosphere with a temperature near its softening point, and then an upper mold is placed on it and pressure is applied to the upper and lower plaster molds to create a denture. A method of manufacturing can be adopted. In order to improve the releasability of the resulting denture from the plaster mold, a fluororesin dispersion is applied to the surface of the plaster mold on which the aromatic polyimide coating layer has been formed prior to compression molding. is desirable.

As the above-mentioned fluororesin, polytetrafluoroethylene, polychlorotrifluoroethene, tetrafluoroethylene/hexafluoropropylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, etc. can be used.

(Example) Examples are shown below.

Example 1 A wax denture was made using a plaster film mold of a sterile maxillary jaw, followed by implantation and pouring wax to prepare a two-part plaster mold for making a floor denture.

After drying the lower mold at 180°C for 1 hour, a varnish of aromatic polyamic acid was applied, and then a dispersion of polytetrafluoroethylene was sprayed.
Heat at ℃ for 30 minutes. A polysulfone plate was placed on the lower mold on which the aromatic polyimide coating layer had been formed, and the polysulfone plate was heated at 350°C for 5 minutes to soften the polysulfone. Then, the upper mold, which had been previously dried at 150°C, was placed and compression molding was performed. I went.

The surface of the molded denture was smooth, and the separation between the plaster mold and the denture was very good.

Comparative Example 1 The same method as in Example 1 was repeated except that the aromatic polyamic acid varnish was not applied.

Powdered gypsum was attached to and mixed in the surface of the molded denture, and the entire surface was white.
In addition, the surface of the denture is not shiny and shiny,
It needed polishing.

Example 2 An upper mold and a lower mold on which aromatic polyimide coating layers were formed were prepared in the same manner as in Example 1. Next, install the upper mold into the fixed mold and the lower mold into the movable mold of an injection molding machine with the mold temperature set at 130°C, and set the temperature of the plaster surface to 130°C.
℃, and injection molding of polysulfone was performed at a cylinder temperature of 330℃.

The surface of the obtained denture was smooth, and the separation between the plaster mold and the denture was very good.

Claims (1)

[Claims] 1. A plaster mold for manufacturing dentures, the surface of which is coated with an aromatic polyimide coating layer. 2. Using a plaster mold for manufacturing dentures that has an aromatic polyimide coating layer formed on its surface,
A method for manufacturing dentures characterized by molding thermoplastic resin.