JPS63270325A - Mold material for molding - Google Patents

Abstract

PURPOSE:To remove crack occurrence of the surface of mold material and improve mold releasing properties, by adding a nonionic surfactant having a specified HLB value and boron nitride on the cavity surface of the mold for crystallized glass. CONSTITUTION:A nonionic surfactant such as sorbitane fatty acid ester having <=3 HLB value is added in an amount of 0.1-30g per 100g substrate on at least molding face of a molding mold. Further as necessary boron nitride is added thereto. The surfactant and boron nitride are added until attaining depth of at least about 10mum from the molding face of the mold. Although the surfactant is permitted to exist preferably near molding face of the molding material, the surfactant may be also mixed in whole the mold. The surfactant is preferably present in the mold, when the mold material is cured and even if the surfactant is loosen by heat treatment after curing, it has no trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a molding material, particularly a molding material used in molding dental materials, artificial bones, artificial joints, etc. made of crystallized glass.

(Prior Art) Conventionally, attempts have been made to apply crystallized glass to dental materials, artificial bones, artificial joints, and the like.

In particular, calcium phosphate-based crystallized glass has good compatibility with living organisms because its components are similar to those of living teeth and bones, its properties are very similar to natural teeth, and its fluidity in the molten state is excellent. It is expected to be used as a dental material because it can be formed by precision casting similar to that of dental metals.

Conventionally, casting molding using a lost wax method has been used to mold this type of material. In the lost wax method, a paraffin wax model (wax pattern) is embedded in a slurry called an investment material, and after the slurry has hardened, the entire body is heated and the wax pattern is incinerated. Pour and mold,
Thereafter, a crystallization treatment was performed to obtain crystallized glass.

(Problems to be Solved by the Invention) However, there is a drawback in that fine racks are generated on the surface of the mold material due to volume changes when the slurry dries and hardens.

If cracks occur on the surface of the mold material, when molten glass is cast, the glass will penetrate into the cracks and cause cracks in the molded product. In severe cases, the mold collapses, the mold material gets mixed into the molded product, or protrusions form on the molded product, resulting in a significant drop in dimensional accuracy.

(Means for Solving the Problems) As a result of various studies and examinations aimed at obtaining a mold material without cracks on the surface, the inventor found that the molding surface (the surface in contact with the object to be molded) of the mold material for molding. discovered that the above object could be achieved by adding a specific surfactant.

Thus, the present invention provides a molding material characterized in that a nonionic surfactant having an HLB value of 3 or less is added to at least the molding surface of the mold.

In the present invention, the surfactant must be nonionic.

Cationic and anionic surfactants are not suitable because they have no effect on suppressing cracks on the surface of the mold material.

Further, it is necessary that the HLB value of the nonionic surfactant is 3 or less. If the HLB value exceeds 3, it is unsuitable because there is no effect of suppressing crack generation. Among this range, those with an HLB value of 2 or less are preferable because they have a particularly high effect of suppressing crack generation. Also, the surfactant should be at least 10 g from the molding surface of the mold.
It is preferable to add it to a depth of at least 50 pm, preferably at least 50 pm. If this depth is less than 10 pm, it is not preferable because there is a possibility that the generation of cracks cannot be suppressed.

Further, the amount of the surfactant added is preferably 0.1 to 30 g per 100 g of the mold base material constituting the mold material, and if the amount added is less than 0.1 g, it has the effect of suppressing crack generation. does not appear, and conversely, if the amount added exceeds 30g, the mechanical strength of the mold will decrease and there is a risk that the mold will collapse, so this is not preferable, and within these ranges, the amount of surfactant added is 0.4 to 1 per 100g of mold base material
When it is 0 g, the effect of suppressing crack generation is particularly high, and the surface smoothness of the molded article is excellent, so it is particularly preferable.

In the present invention, the mechanism by which the surfactant suppresses crack generation is not necessarily clear.
It seems to have the function of keeping the rate of curing constant and not causing internal stress. In fact, the surfactant only needs to be present when the molding agent is cured, and there is no problem even if it is lost from the mold by subsequent heat treatment or the like.

Examples of the surfactant used in the present invention include sorbitan fatty acid ester, sorbitan trioleate, tsuru and tan stearade, and polyoxyethylene monostearate. These properties may be liquid or solid. In the case of a solid, it can be dissolved in a suitable solvent such as benzene, alcohol, etc. and mixed into the mold base material slurry.

The mold base material to which the surfactant is added is not particularly limited, and examples include magnesium phosphate, silicate, alumina, aluminum phosphate, zirconia, etc.
Gypsum-based materials or the like may be used as appropriate.

Further, the surfactant may be present at least near the molding surface of the mold material as described above, but it may be mixed throughout the mold if desired.

In fact, as a means for producing a molding material according to the present invention, for example, a wax pattern is buried in a mold base material slurry to which the surfactant is added, the slurry is hardened, and then the wax pattern is incinerated. There are ways to remove it. Further, the mold base material slurry to which the surfactant has been added is coated on a wax pattern by a coating method or a dipping method to first form a molding surface of the mold, and then the wax pattern with the coating layer is coated with the wax pattern. By embedding the mold material in an ordinary mold base material slurry that does not contain a surfactant, curing the slurry, and removing the wax pattern by means such as incineration, a mold material in which the surfactant is added only to the molding surface is obtained. method may also be adopted. In addition to wax patterns, ordinary molds can also be used, but since the mold must be removed mechanically, there are restrictions on the shape of the mold, and it is difficult to use for complex materials such as dental materials. For those having a shape, it is preferable to use a wax pattern.

Alternatively, the molding surface can be formed by applying a mold base material slurry to which the surfactant has been added to the surface of a mold material that has been molded in advance.

Furthermore, in the present invention, by adding boron nitride to at least the molding surface of the mold together with the surfactant,
The mold releasability can be improved by suppressing the reaction between the molding material and the object to be molded.

It is preferable that boron nitride is added together with the surfactant to a depth of at least 10 μm from the molding surface of the mold.
If the depth of the layer to which boron nitride is added is less than 10 pm, it is not preferable because there is a risk that a sufficient mold release effect will not be exhibited.

As can be easily inferred from the above explanation, boron nitride may be present only on the surface of the mold, but it may be present throughout the mold.

In addition, the amount of boron nitride added is 10 per 100 g of mold base material.
The amount is preferably ~400g. If the amount of boron nitride added is less than 10g, sufficient mold release effect will not be achieved, and if the amount added exceeds 400g, the mechanical strength of the mold material will decrease. This is not preferable because there is a risk of this, and within these ranges, the amount of boron nitride added to the mold base material is
When the amount is 30 to 100 g per g, it is particularly preferable because both the mold release effect and the mechanical strength of the mold material can be improved most effectively.

When adding boron nitride, the amount of nonionic surfactant with an HLB value of 3 or less strictly depends on the amount of boron nitride added, but it is 0.1 to 150 g per 100 g of mold base material.
It is preferable that

Further, boron nitride is preferably a powder with a particle size of 150 gm or less, particularly preferably a powder with a particle size of 30 μm or less, from the viewpoint of improving mold releasability, mold surface smoothness, and mold strength.

The material molded using the molding material according to the present invention includes, for example, Ca041 to 49.5 mol%, P2O558,5 to
Calcium phosphate crystallized glass containing 50% Al2O30 and 5 to 5 mol% is preferably used, but it can also be used to mold metals and other crystallized glasses.

Further, as a method for producing crystallized glass using the mold material according to the present invention, it is possible to adopt a method of crystallizing the glass after forming it by, for example, commonly performed centrifugal casting, vacuum compression casting, press molding, or the like. For example, crystallization is carried out at a temperature of 500~
This can be carried out by heat treatment at 900°C for 5 minutes to 100 hours.

(Example) Example 1 Sorbitan trioleate (Nonionic surfactant 5S30, HLB-1, 7, manufactured by Nikko Chemicals) 1 g, phosphate-based investment material (Bluebest, manufactured by Tokuyama Soda) powder 20
g and 40 g of its exclusive kneading solution were thoroughly mixed to obtain a uniform slurry. This was applied to a crown-shaped wax pattern with a sprue wire attached to form a surface layer of about 200 pm.Then, the whole was placed in a metal casting ring, and the phosphate-based investment material It was buried by After the investment material was cured at room temperature, it was heated to 700° C. and the wax pattern was removed by incineration to obtain a mold for making a dental crown. While keeping this mold at 700℃,
CaO 47 mol%, Al2O2 2 mol% melted at °C
A glass melt having a composition of 551 mol% of P2O was cast by a centrifugal casting method. Thereafter, it was held together with the mold at 700°C for 5 hours to crystallize it.

Next, the mold was broken using plaster forceps to take out the molded body, and the sprue wire was cut to obtain a crystallized glass dental crown.

The obtained tooth crown had no surface gloss due to the reaction between the glass and the casting, but no protrusions or cracks were observed, and a glossy surface was obtained by polishing it in the same way as a cast metal crown.

The dimensional change from the wax pattern of this tooth crown is 30g.
m or less.

Example 2 Sorbitan fatty acid ester (Ionet manufactured by Sanyo Chemical Co., Ltd.)
S85. 10 g of HLB 1.8), 20 g of boron nitride powder, and 30 g of ethyl silicate binder (HAS-10 manufactured by Colcoat) were thoroughly mixed to obtain a uniform slurry. This was applied to the wax pattern obtained in the same manner as in Example 1 to form a surface layer of about 20,071 m of the mold material, and the same procedure as in Example 1 was repeated to obtain a crystallized glass dental crown.

The crystallized glass cast body had good release from the mold and could be easily taken out from the mold. In addition, the surface of the obtained tooth crown was smooth and shiny when removed from the mold, and no cracks or protrusions were observed.The dimensional change of this tooth crown from the wax pattern was less than 20 lm. Met.

Claims (7)

[Claims] (1) A mold material for molding, characterized in that a nonionic surfactant having an HLB value of 3 or less is added to at least the molding surface of the mold. (2) Nonionic surfactants with an HLB value of 3 or less are
The molding material according to claim 1, wherein the molding material is added to a depth of at least 10 μm from the molding surface of the mold. (3) The mold material for molding according to claim 1 or 2, wherein the amount of nonionic surfactant having an HLB value of 3 or less is 0.1 to 30 g per 100 g of mold base material. (4) A mold material for molding, characterized in that a nonionic surfactant having an HLB value of 3 or less and boron nitride are added to at least the molding surface of the mold. (5) The molding material according to claim 4, wherein the nonionic surfactant having an HLB value of 3 or less and boron nitride are added to a depth of at least 10 μm from the molding surface of the mold. (6) The amount of the nonionic surfactant with an HLB value of 3 or less and boron nitride is 0.1 to 150 g of surfactant and 10 to 400 g of boron nitride per 100 g of mold base material. The mold material for molding according to item 4 or 5. (7) The mold base material constituting the mold material is magnesium phosphate-based, silicate-based, alumina-based, aluminum phosphate-based, zirconia-based, or gypsum-based.
A mold material for molding as described in any one of the paragraphs.