JPH0447643B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention involves molding thermoplastic resin by injection molding, extrusion molding, transfer molding, compression molding, etc. using a plaster mold surrounding a denture base-shaped cavity surrounded by a flask. This invention relates to a resin denture base reinforced with alumina fibers obtained by crushing a plaster mold after cooling and hardening. BACKGROUND ART Conventional resin denture bases have been made of acrylic resins for many years and have been obtained by pressure molding by heating and polymerizing polymers and monomers. This has the advantage that repair is easy because the same acrylic polymer powder and acrylic monomer liquid are used as repair materials. However, denture bases obtained by heating polymerization of such acrylic resins are brittle, and the thin portions often break due to occlusal force, resulting in poor strength and the heating polymerization reaction is often insufficient. It also had hygienic drawbacks, such as leaching and causing allergic symptoms. Therefore, in order to eliminate such drawbacks, injection molding or compression molding of thermoplastic resin such as polysulfone using a plaster mold has been proposed and has come into practical use. Thermoplastic resins such as polysulfone have better impact resistance than conventional acrylic resins, so they have the advantage of providing stronger denture bases than acrylic denture bases. If the walls of the mouth part are made thinner in order to better sense temperature and temperature, there is a problem in that they lack rigidity and are prone to bending. In addition, thermoplastic resins such as polysulfone tend to cause stress cracking when they come into contact with acrylic monomer liquid, making it difficult to repair and requiring long-term repair as the immediate polymerization resin used for conventional acrylic resin denture bases cannot be used. The reality was that it could not stand up to its use. However, since no repair material has been proposed to replace acrylic monomers, there has been a strong need for a reinforced thermoplastic resin denture base that can sufficiently withstand acrylic monomers. Problems to be Solved by the Invention It is an object of the present invention to provide a reinforced thermoplastic resin denture base that can eliminate such conventional drawbacks. In other words, a resin denture base obtained by molding a thermoplastic resin using a plaster mold surrounding a denture base-shaped cavity and crushing the plaster mold has high strength and rigidity, and is resistant to cracking even when exposed to acrylic monomer liquid. The object of the present invention is to provide a reinforced resin denture base that will not grow or break. Means for Solving the Problems The present invention is characterized by molding a thermoplastic resin by injection molding, extrusion molding, transfer molding, compression molding, etc. using a plaster mold surrounding a denture base-shaped cavity. A reinforced resin denture base obtained by crushing a resin denture base, wherein the thermoplastic resin is composited with 5 to 500 parts by weight of alumina fiber based on 100 parts by weight of the resin. It's the floor. The thermoplastic resin used in the present invention is one that does not undergo thermal deterioration during the molding method, has an appropriate viscosity, has good moldability, and can be colored to resemble the color of the gums. The resin is required to have appropriate rigidity, moisture resistance, and toughness that does not cause stress cracks during use. Therefore, polystyrene, polymethyl methacrylate, polymethylpentene-1, transparent nylon, polycarbonate, polyarylate, polyester carbonate, polyethylene terephthalate, transparent ABS, polysulfone resins, etc. are used, but in particular polysulfone, polyethersulfone Polysulfone-based resins such as Polysulfone resins are preferred because they have excellent moisture resistance, rigidity, stress cracking resistance, and the like. The polysulfone resin used as a preferred embodiment in the present invention is defined as a polyarylene polyether polysulfone in which arylene units are located randomly or orderly with ether and sulfone bonds. for example UCC polysulfone Udel with the structure

Polyether sulfone Victrex manufactured by ICI with the structure of [Formula]
can be mentioned. The alumina fiber used in the present invention is alumina (Al ₂ O ₃ ) in a fibrous form. Alumina is usually produced by calcining aluminum hydroxide (Al ₂ O ₃ nH ₂ O) or aluminum salt, and is amorphous, ρ−, χ−, γ−, η−, δ
There are many types such as -, κ-, θ-, and α-Al ₂ O ₃ , each with different structures and physical properties. At high temperatures, both become α-Al ₂ O ₃ and are the most stable. The method for producing alumina fibers is not particularly limited. For example, a method for pulling α-Al ₂ O ₃ single-crystal continuous fibers from alumina melt (Japanese Patent Publication No. 46-
16082), a method of spinning a mixed solution of aluminum salts and organic polymers and firing the resulting fibers to make alumina fibers (Japanese Patent Application Laid-open No. 47-718), spinning a spinning solution consisting of alumina sol onto a belt conveyor to form continuous fibers. A method of obtaining continuous alumina fibers by brushing off the fibers and firing them directly (Japanese Patent Application Laid-Open No. 50-39311), a method of spinning a solution of an inorganic polymer having a main chain consisting of -Al-O-, and producing precursor fibers. It can be obtained by a method such as a method of obtaining alumina fiber by firing (Japanese Patent Publication No. 51-12736). Alumina fibers have different properties depending on their manufacturing method.
For example, the specific gravity is 2.5~3.99, and the fiber diameter is 3~
250μm, tensile strength 100-260Kg/ ^mm2 , tensile modulus
It has a weight of 10 to 46 t/mm ² and its shape includes wool-like short fibers and continuous fibers. Although any alumina fiber can be used in the present invention, continuous fibers are preferable because they have a higher reinforcing effect and significantly improve rigidity and acrylic monomer resistance than wool-like short fibers.
The elastic modulus of alumina continuous fibers is approximately three times that of glass fibers and comparable to that of carbon fibers. Carbon fiber is black and is not aesthetically desirable for use in reinforcing denture bases. There are no particular limitations on the method of compositing the thermoplastic resin and the alumina fibers. For example, after premixing alumina fibers of an appropriate length with the resin,
Melt and knead to disperse alumina fibers in the resin,
Molded products such as pellets, sheets, plates, etc., as well as injection molding, extrusion molding, transfer molding,
A method of obtaining a denture base reinforced by compression molding, etc., in which a cloth, mat, tape, etc. made of alumina fiber is placed in a predetermined place in a plaster mold surrounding a denture base-shaped cavity, and a thermoplastic resin is placed around it. Methods such as injection and filling to obtain a reinforced denture base are applied. The appropriate amount of the alumina fiber to be combined with the thermoplastic resin is 5 to 500 parts by weight based on 100 parts by weight of the resin. If the fiber is less than 5 parts by weight, the effect of improving rigidity and acrylic monomer resistance will be small, and if it exceeds 500 parts by weight, the formability of the denture base will decrease, creating narrow gaps between artificial teeth and Filling of thin-walled parts such as shell parts becomes insufficient. 5 to 500 parts by weight is appropriate, but 10 to 300 parts by weight is preferred because it provides a better balance between reinforcing effect and moldability. The thermoplastic resin used in the present invention or the composite of the resin and alumina fiber may contain antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, dyes, etc., to the extent that the object of the present invention is not impaired. It is possible to obtain a denture base reinforced with one or more conventional additives, such as coloring agents such as pigments. Function: Since the denture base of the present invention is obtained from a composite of thermoplastic resin and alumina fiber, the reinforcing effect of the alumina fiber, which has high strength and elastic modulus, provides high rigidity even in the thin parts of the denture base, making it difficult to bend. ,
In addition, alumina fibers are dispersed in designated areas of the denture base,
Or, since alumina fiber cloth is embedded inside the molded product, even if cracks occur in the thermoplastic resin due to contact with the acrylic monomer,
It is believed that the cloth or the aggregate of the fibers inhibits the propagation and growth of cracks, prevents substantial breakage, and improves the resistance to acrylic monomers. Hereinafter, the present invention will be specifically explained with reference to Examples, but these are merely illustrative of preferred embodiments, and the present invention is not limited to the scope of the Examples. Example After heating the flask in which the denture base wax model was embedded to soften and flow the wax, alumina fibers having a shape and area corresponding to the mouth part of the denture base were placed on the plaster mold at the bottom of the flask. I placed the cross. The alumina fibers were obtained by spinning a solution of an inorganic polymer having a main chain consisting of -Al-O- and firing the resulting precursor fibers, and had a specific gravity of 3.2, a fiber diameter of 9μ, It is a plain weave cloth made of continuous fibers with a tensile strength of 25t/ ^mm2 . Polyether sulfone (Victrex manufactured by ICI) was placed on the plaster mold where the cloth was placed for denture base formation.
By positioning a U-shaped molded product colored like gingiva (4100G) and blowing hot air at 380℃,
After softening the molded product, it was compression molded using a compression molding machine, and then allowed to cool naturally. The ratio of the cloth made of the resin and the fibers was 60 parts by weight of the fibers to 100 parts by weight of the resin. After cooling, the upper and lower flasks were separated, the plaster mold was divided, and the denture base molded product was taken out. A good product was obtained that had a shape that was faithful to the predetermined shape, had a high rigidity at the mouth part, and was not easily deflected. In addition, the denture base molded product was brought into contact with an instant polymerization resin for denture repair (trade name: GC Repairasin) containing acrylic monomers, etc., which is used for repairing conventional acrylic resin denture bases, using a conventional method. However, we used the brush-laying method to build up the denture base, but only very small cracks were observed.
It was confirmed that the instant polymerization resin for denture repair can be used. Comparative Example The same operation as in the example was carried out except that the alumina fiber cloth used in the example was not used. The resulting denture base lacked rigidity in the mouth area and was easily deflected. In addition, large cracks occurred due to contact with instant polymerization resin for repair, making it virtually impossible to use. Effects of the Invention As described above, the present invention has the following effects because the denture base is formed by a composite of thermoplastic resin and alumina fiber. (1) High rigidity, making thin parts such as the mouth part less susceptible to deflection. Therefore, it is possible to make the wall thinner,
It is possible to obtain a denture base that makes it easier to feel the temperature of food and has improved taste. (2) It becomes possible to use instant polymerization resins used for repairing conventional acrylic resin denture bases. (3) Since the alumina fibers suppress molding shrinkage of the resin, a denture base with dimensions that are more faithful to the original shape and less deformed due to residual strain can be obtained. (4) Since alumina fibers are colorless and transparent, the resulting denture base has a good appearance and is aesthetically pleasing.

Claims (1)

[Claims] 1. In a resin denture base obtained by molding a thermoplastic resin by injection molding, extrusion molding, transfer molding, compression molding, etc. using a plaster mold surrounding a denture base-shaped cavity, and crushing the plaster mold, A reinforced resin denture base, characterized in that the thermoplastic resin is composited with 5 to 500 parts by weight of alumina fiber based on 100 parts by weight of the resin.