JPS61134305A - Separation agent for molding of denture base - Google Patents

Abstract

PURPOSE:To obtain a separating agent for the molding of a denture base, capable of improving the releasability of a resin from gypsum mold, by adding specific amounts of a liquid silicone rubber and a fluororesin to an organic solvent used conventionally in the forming of a denture base from a thermoplastic resin. CONSTITUTION:The objective separation agent for the molding of a denture base is produced by mixing (A) 100pts.wt. of an organic solvent, e.g. halogenated hydrocarbon such as trichloroethylene with (B) 3-20pts.wt. of a liquid silicone rubber of formula (R is methyl, phenyl, vinyl, etc.; X is OH or vinyl) and (C) 0.5-20pts.wt. of a fluororesin such as tetrafluoroethylene resin. The separation agent facilitates the release of a molded denture base from gypsum mold in the injection molding, extrusion molding, compression molding, etc., of a thermoplastic resin (especially preferably polysulfone resin from the viewpoint of excellent moisture-resistance, rigidity, stress-cracking resistance, etc.).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a separating agent for denture base molding that improves the separability between the resin and the plaster mold when molding the denture base using a thermoplastic resin.

Conventional technology Traditionally, compression molding has been used to manufacture denture bases by molding a mixture of acrylic monomers and polymers and then polymerizing at room temperature or by heating. Denture bases using superior thermoplastic resins have been developed and are attracting attention.

As methods for manufacturing denture bases using thermoplastic resins, injection molding (Japanese Patent Publication No. 57-2028), extrusion molding, and compression molding (Japanese Patent Application Laid-open No. 58-1489) are already known.

In either case, a melted and softened thermoplastic resin is injected, extruded, or placed into a flask containing an artificial tooth to form a shape, and is taken out after cooling and solidifying.

In the conventional compression molding method using a mixture of acrylic monomers and polymers, a rice cake-like mixed resin is placed in a prepared mold, the upper and lower parts of the flask are closed, the flask is placed in a flask press, and after the pressure molding , polymerization is carried out at room temperature or by heating, but since the boiling point of acrylic monomer is 100"C, the polymerization process is usually carried out below 100"C.Therefore, the heat resistance of the separating agent between the resin and the mold material used during denture base molding is A temperature of 100"C is sufficient, and it is sufficient that the material does not react with acrylic monomers and has the property of preventing moisture.
Generally, a sodium alginate aqueous solution is used. When this is applied to a stone or plaster surface, the Ca on the plaster surface is
This is thought to be due to the formation of a calcium alginate film that is insoluble in water.

However, the injection molding method using the thermoplastic resin,
In the extrusion molding method and the compression molding method, it is necessary to melt and soften the thermoplastic resin, so the resin has a temperature of 200"C to 400"C.
The temperature is raised to 'C, and the 4i2i fat at that temperature comes into contact with the plaster mold, is strongly pressed, and is shaped.

In particular, in the compression molding method using the thermoplastic resin,
Because it is necessary to heat and soften the thermoplastic resin on the plaster mold in the lower flask, the temperature of the plaster mold is also 200°C to 400°C.
The temperature rises to

Therefore, the separating agent coated on the plaster mold is approximately 4
A material that can withstand temperatures of 00°C is required, but the above-mentioned sodium alginate has insufficient heat resistance, deteriorates significantly during compression molding, and does not function as a separating agent.

Problems to be Solved by the Invention The present invention shows good separability between the resin and the plaster mold in injection molding, extrusion molding, compression molding, etc. using thermoplastic resin, and provides a molded denture base. The object of the present invention is to provide a separating agent that allows easy removal of the molten metal from a plaster mold.

Means for Solving the Problems The present invention is characterized by a denture base containing 3 to 20 parts by weight of liquid silicone rubber and 0.5 to 20 parts by weight of fluororesin per 100 parts by weight of an organic solvent. It is a separating agent for molding.

The liquid silicone rubber used in the present invention is a linear diorganopolysiloxane represented by the general formula,
The terminal group X reacts with the crosslinking agent to form a rubber elastic body. Most of R is a methyl group, but those into which a phenyl group or a vinyl group is partially introduced are also used.

For X, a hydroxyl group is used in the condensation reaction, and a vinyl group is used in the addition reaction. There are no particular restrictions on the viscosity of the polymer, but 100
~100,0OOC5 (25'C), a,
ooo to about 20,0OOC5 is preferable since physical properties and workability are well-balanced.

The fluororesin used in the present invention refers to fluorine atoms (
F), examples of which include tetrafluoroethylene resin, tetrafluoroethylene barfluoro, alkyl vinyl ether copolymer resin, and tetrafluoroethylene-hexafluoropropylene copolymer resin. , tetrafluoroethylene-ethylene copolymer resin, trifluorochloroethylene resin, vinylidene fluoride resin, and the like.

In particular, tetrafluoroethylene resin has high heat resistance, up to 400"C
However, since it does not flow, the separation function is more stable,
preferable.

Organic solvents in the present invention include hydrocarbon solvents such as hexane, halogenated hydrocarbons such as trichloroethylene, amines, alcohols, ethers, ketones, esters of ethyl acetate, acids, dimethyl sulfoxide,
Any solvent release agent such as N-methylpyrrolidone or dimethylformamide can be used, but halogenated hydrocarbons are preferred from the viewpoint of affinity with liquid silicone rubber and fluororesin and uniformity of dispersion.

In addition, from the viewpoint of workability when coating the plaster mold and removability of the solvent after coating, those having a boiling point of 50 to 150°C are preferable, and among halogenated hydrocarbons, 1,1,1-trichloroethane CWIa point 74 .0'C), 1, 1
, 2-TO'J riOJL/ethane (boiling point 1115-C
), 1.1,1.2-tetrachloroethane (boiling point 129
．． 2”C), trichlorethylene (boiling point 87.2°C),
Particularly preferred is tetrachlorethylene (boiling point 121.2°C).

In the present invention, the content of liquid silicone rubber and fluororesin in the organic solvent is preferably 8 to 20 parts by weight of liquid silicone rubber and 0.5 to 20 parts by weight of fluororesin per 100 parts by weight of organic solvent. It is.

The amount of fluororesin is 0.0% per 100 parts by weight of the organic solvent. '5
Even if it contains ~20 parts by weight, if the liquid silicone rubber is less than 3 parts by weight, the fluororesin will not retain well on the plaster mold because it will not have sufficient film formation properties during the plaster mold coating process. , the separation effect between the resin and the plaster mold is insufficient. If the liquid silicone rubber exceeds 20 parts by weight, the liquid viscosity becomes too high and uniform coating becomes difficult, making it impossible to obtain a stable and uniform separation effect.

Even if the liquid silicone rubber contains 8 to 20 parts by weight per 100" parts by weight of the organic solvent, 0.5 parts by weight of the fluororesin
If it is less than 20 parts by weight, the separability between the resin and the plaster mold will be insufficient, and if it exceeds 20 parts by weight, the uniformity of dispersion of the fluororesin will decrease and it will be difficult to obtain a uniform coating, which is not preferred. In particular, when the fluororesin is contained in an amount of 1 to 10 parts by weight, the coating workability and the separation effect between the resin and the plaster mold are excellent, so it is more preferable.

To the separating agent consisting of the organic solvent, liquid silicone rubber, and fluororesin, other resins, inorganic fillers, dispersants,
It is also possible to incorporate additives and reinforcing agents such as stabilizers and colorants.

There are no particular limitations on the method of coating the plaster mold with the separating agent. Any method commonly used for coating metal with paint, such as applying with a brush or spraying, can be applied.

After application, the organic solvent is allowed to stand at room temperature for several minutes to several tens of minutes to volatilize the organic solvent and form a film on the plaster mold.

Methods such as removing the solvent through a suitable heat treatment, baking at a temperature higher than the melting point specific to each fluororesin to make the coating stronger, and then using it for denture base molding are applied.

The thermoplastic resin used in the present invention does not undergo thermal deterioration in the molding method and has an appropriate viscosity,
It is required that the resin has good moldability, can be colored to resemble the color of the gums, has appropriate rigidity and moisture resistance, and is tough enough to not cause stress cracks during use. Ru. Therefore, polystyrene, polymethyl methacrylate, polymethyl pentene-1, transparent nylon, polyethylene terephthalate, polycarbonate, polyarylate, polyester carbonate, transparent ABS resin, polysulfone resin, etc. are used, but in particular polysulfone, polyether Polysulfone-based resins such as sulfone 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■ and Engineering CI
! Polyether CyLt * :/ Victore
x” is mentioned.

Function: The separating agent of the present invention consisting of an organic solvent, liquid silicone rubber, and fluororesin is applied to predetermined areas of a river plaster mold for denture base molding, the solvent is removed by air drying or appropriate heat treatment, and the fluororesin is further applied as necessary. By firing at a temperature equal to or higher than the melting point of the resin, the separation between the resin and the plaster mold after molding the denture base becomes extremely good.

This is because the organic solvent disperses the liquid silicone rubber and fluororesin sufficiently uniformly to form a viscosity suitable for coating the plaster mold, and the liquid silicone rubber has excellent film-forming ability and adhesion to the plaster. A thermoplastic resin that is melt-molded and has a uniformly dispersed fluororesin that crosslinks appropriately after application and holds the fluororesin firmly on the plaster mold! ! ! It is presumed that it works to improve the separation between the denture base and the plaster mold.

The effects of the above-mentioned components are effective not only in denture base molding using thermoplastic resins, but also in conventional compression molding methods using mixtures of acrylic monomers and polymers, showing a high separation effect. It is also highly effective in separating plaster models from buried river gypsum, and between gypsum and wax.

Hereinafter, the present invention will be specifically explained with reference to examples, but these are merely illustrative of preferred embodiments and are not limited to the scope of the examples.

Example 1 A flask in which a denture base wax model was embedded was heated to soften and flow the wax, and then a mixture of 100 parts by weight of 1,1,1-trichloroethane was poured into the mold cavity of a plaster mold at the bottom of the flask. 8 parts by weight of liquid silicone rubber having a skeleton of dimethylpolysiloxane (Buscoke manufactured by Cemedine),
Tetrafluoroethylene resin powder CICI Fluon L16
9) A separating agent containing 4 parts by weight was thoroughly shaken, and a uniformly dispersed separating agent was applied thinly with a brush. After a few minutes of air drying, aso
"C" for 10 minutes.

Polyethersulfone (I CI %Vi
ctrex' 200p) U colored like gingiva
The shaped molded product was placed in position, and the molded product was softened by blowing hot air at 880° C. After that, the molded product was compression molded using a compression molding machine, and then allowed to cool naturally.

After cooling, the upper and lower flasks were separated, the plaster mold was divided, and the denture base molded product was taken out. There is almost no plaster attached to the denture base, and all plaster can be removed just by pressing lightly with your hands.
A good denture base molded product with no visible scratches was obtained.

Example 2 As a separating agent, liquid silicone rubber (Bath Coke manufactured by Cemedine) was added to 100 parts by weight of trichlorethylene.
The same test as in Example 1 was carried out except that 15 parts by weight and 10 parts by weight of tetrafluoroethylene resin powder (Fluon L169 manufactured by ICI) were used, but the resin and the plaster mold were well separated. Comparative Examples 1 to 4 As a separating agent, the same liquid silicone rubber and tetrafluoroethylene resin powder as used in Example 1 were added to 100 parts by weight of 1.1.1-trichloroethane in Table 1. An experiment similar to that in Example 1 was conducted using a combination of the following. The results are shown in Table 1. None of them showed good properties as a separating agent.

Table 1 Note) ○...Good, A thin layer of sodium alginate aqueous solution (Acrosep ■ (pink color), manufactured by Ryozen Dentistry Kogyo Co., Ltd.) was applied with a brush to the surface, and a film was formed by drying at room temperature for 10 minutes.

The subsequent steps were carried out under the same conditions as in the example. The sodium alginate coating after the plaster mold was divided was charred black and deteriorated, making it extremely difficult and time consuming to completely remove the plaster from the denture base molding.

Effects of the Invention As described above, the present invention improves the separability from the plaster mold by using an organic solvent containing liquid silicone rubber and fluororesin as a separating agent for thermoplastic resin denture base molding. is extremely good, the moldability is greatly improved, and a good denture base can be stably obtained, resulting in the effect of dramatically expanding the practical range of the denture base.

Claims (1)

[Claims] 3 to 3 parts of liquid silicone rubber per 100 parts by weight of organic solvent
A separating agent for denture base molding, characterized in that it contains 20 parts by weight of a fluororesin and 0.5 to 20 parts by weight of a fluororesin.