JPS61215223A - Method of forming calcium phosphate glass - Google Patents

Abstract

PURPOSE:To prevent a reaction of a mold material with molten glass, and to obtain a molded article of calcium phosphate having high dimensional accuracy, containing neither foams nor admixtures, by setting a layer containing boron nitride on the surface of a mold for molding. CONSTITUTION:A layer containing >=1wt% boron nitride with >=about 10mum thickness is formed on the surface of a mold for molding by CVD method, sputtering method, etc., to form a reaction inhibitory layer to molten glass. Then, glass melt containing >=90wt% calcium phosphate is cast into a mold, cooled and solidified. A reaction of the molten glass and a molding material can be inhibited by this method, and calcium phosphate glass having improved surface properties and high dimensional accuracy can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming calcium phosphate glass.

[Prior Art] Bioactive ceramics have attracted attention as artificial bone materials and human bone materials, and many reports have been made, such as hydroxyapatite sintered bodies and lucium triphosphate sintered bodies. However, artificial bones, artificial teeth, and the like have complex and uneven shapes, and require high dimensional accuracy. It is very difficult to obtain such a molded body using these sintered bodies.

Therefore, as a ceramic material from which such a molded body can be obtained, the development of crystallized glass materials has proceeded, and calcium phosphate crystallized glass has been reported in Japanese Patent Publication No. 11825-1982. In this method, a shape is imparted to a melt of calcium phosphate glass when it is solidified and vitrified, and the glass is crystallized to obtain crystallized glass.

It has been reported that gypsum-based investment materials and phosphate-based investment materials can be used as mold materials for molding this calcium phosphate glass (Japanese Patent Application Laid-Open No. 5S-141509).
I, gypsum-based investment materials react violently with calcium phosphate glass at approximately 700°C, and release SO2 gas, which causes the formed glass to contain air bubbles and reduce the strength of the resulting crystallized glass. In addition, since a reaction layer is formed between the mold material and the glass, it is difficult to separate the glass molded body from the mold, and the dimensional accuracy of the obtained glass molded body is low. Ta. On the other hand, although glass molded objects obtained using a sulfur-based investment material do not contain air bubbles like those obtained using a gypsum-based investment material, they still form a reaction layer between the mold material and the resulting glass. There was a drawback that the dimensional accuracy of the molded body was low.

[Problems to be Solved by the Invention] An object of the present invention is to prevent such a reaction between a molding material and molten glass and to obtain a calcium phosphate glass molded body containing no air bubbles or foreign matter with high dimensional accuracy. It is something to do.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and involves pouring a melt containing 80% by weight or more of calcium phosphate into a mold, and providing a layer that is cooled and solidified to form the mold. The present invention provides a method for molding calcium phosphate glass characterized by the following.

The calcium phosphate glass of the present invention is not particularly limited as long as it contains 90% by weight or more of calcium phosphate, but it is preferable that the calcium phosphate has an atomic ratio of Ca/P of 0.35 to 0.7 and is Al. , Ca/
If P is larger than 0.7, it is difficult to solidify the melt as glass, and if it is smaller than 0.35, the resulting glass has poor water resistance and cannot be used in the atmosphere. Have difficulty.

This kind of glass melt has very low viscosity and high fluidity, so it is easy to mold, but it also has good wettability with the mold material, so it penetrates into the micropores of the mold material and reacts with the mold material. It was found that it was easier to form a reaction layer by doing this. Therefore, as a result of investigating various mold materials that are less likely to cause such reactions, we found that by reducing the wettability of the mold material with glass,
It has been found that the formation of this reaction layer can be largely suppressed.

Furthermore, as a result of various studies on how to create a mold material with low wettability due to rT terraces, we found that by providing a layer containing boron nitride, carbon, or calcium fluoride on the surface of the mold, the wettability of the mold with glass could be improved. It was also found that it significantly reduced The layer containing boron nitride, carbon, or calcium fluoride provided on the surface of the mold is referred to as the reaction suppression layer.We investigated a molding method using a mold with a reaction suppression layer on the surface. When molding is performed using a mold with a reaction suppression layer containing carbon, the calcium phosphate glass is reduced and the glass is colored red, and bubbles are likely to be generated due to the generated CO gas. It has been found that when molding is performed using a mold with a reaction suppression layer, air bubbles are likely to be generated due to the generated F2 gas, and when molding is performed using a mold material with a reaction suppression layer containing boron nitride, air bubbles and foreign substances It was found that a good glass molded article without any contamination and without forming the reaction layer between it and the mold could be obtained.

The content of boron nitride in such a reaction suppression layer containing boron nitride is suitably 1% by weight or more, preferably 10% by weight or more, particularly preferably 30% by weight or more. If the amount is less than 1% by weight, the effect of reducing the wettability of the mold material due to glass is insufficient. On the other hand, if the content of boron nitride in one reaction suppression layer is high, the strength of the reaction suppression layer may be maintained depending on the method of forming the reaction suppression layer.

There is an upper limit to the content. If the reaction suppression layer containing boron nitride on the surface of the mold is formed by CVD, sputtering, etc., and the surface layer has a structure in which boron nitride itself has a bonding force, the boron nitride content is The higher the value, the more preferable it is, and when bonding boron nitride powder using a binder such as gypsum, the binder should not be contained at about 10% by weight or more, that is, the content of boron nitride should not be about 80% by weight or less. Because the bonding force of the reaction suppression layer, which is the surface layer of the mold, is low, the reaction suppression layer may collapse due to the inflow of glass melt.The components other than arsenic in the reaction suppression layer are phosphate-based. It is an investment material. The phosphate-based investment material may be one commonly used, such as magnesia (Kg
O), ammonium dihydrogen phosphate (NH4H2POa)
, silicon dioxide (Si02).

Further, as a result of various studies on the thickness of the reaction suppression layer on the surface of the mold containing boron nitride, it was found that the formation of the reaction layer can be sufficiently suppressed if the thickness is 1ILm or more, preferably 10ILm or more. The thickness of this reaction suppression layer is not particularly limited as long as it is thick, but as can be easily inferred from the above explanation, the effect of the reaction suppression layer on the mold surface containing boron nitride is Since it only appears in certain areas, even if the thickness is increased to 100 wins or more, no further improvement in the effect will be seen.

There are no particular restrictions on the method for forming such a reaction suppression layer, but there are methods for forming the surface layer on the surface of the mold by physical methods such as CVD or sputtering, coating on the surface of the mold, spraying, or forming the surface layer on the surface of the mold. A method such as immersing the substrate in a reaction-inhibiting layer forming solution is used. In addition, after forming a reaction suppression layer on the pattern surface by coating or spraying on the surface of the pattern surface (wax pattern in the case of the lost wax method), or by immersing the pattern in a reaction suppression layer forming solution, , a method of creating a mold may also be adopted.

Furthermore, there is no particular restriction on the glass molding method, and press methods, casting methods, etc. may be employed.

[Example] Example 1 Ethyl silicate 40.50%, ethanol 44z.

10 boron nitride powder is added to 25 parts of a solution that was pre-mixed with 5% water and 11% INHG (both weight%) and left for 20 hours.
After mixing and stirring the parts to form a uniform slurry containing about 87% by weight of boron nitride, the slurry was applied to a stainless steel mold shown in Figure 1 to form a reaction inhibitory layer. The thickness was about 200 ILm. In addition, in Figure 1, A = B = 3.1 Peng layer, C = 30.1
+m layer.

Into the mold, 0.8g of phosphoric acid Cal'yfzlU quality glass (
Composition: CaO25% by weight, Al2O32% by weight, p2
o573% by weight) block (3 intestinal layers x 5 m x 20
Place a 1kg load on top of the mold and heat for 700 minutes.
After being placed in an electric furnace at °C for 5 hours, the molded body was cooled and taken out from the mold. The surface of the obtained crystallized calcium phosphate glass is smooth and its dimensions are (3 m ±0
．． 1 serving) x (3 layers ±0.1 serving) x (301
±0. The bending strength of the crystallized glass was 1200 kg/crn'.

Example 2 As Example 2, a method for manufacturing a dental crown by the molding method of the present invention will be described with reference to FIG.

First, as shown in FIG. 2(a), wax pattern 2 for making a dental crown was created by filling a dental plaster mold 1 with heated and melted wax. next.

As shown in FIG. 2(b), a sprue wire 3 was attached to this wax pattern 2, and then set on a rubber cone 4.

Phosphate-based investment material (Tokuyama Soda Blue Best) powder 10
Add 5 parts of boron nitride powder to 1 part of investment material solution.
A uniform slurry containing about 30% by weight of boron nitride was prepared by adding 0 parts of boron nitride and stirring to form a uniform slurry containing about 30% by weight of boron nitride, which was applied uniformly to the surface of the wax pattern on the pear cone to a thickness of about 0.1 to 0.5+++1 (embedded). material layer 11), and further, FIG. 2 (C
) like phosphate-based investment material (Tokuyama Teidai Blue Best)
The slurry-like material 5 is injected into the metal ring 6 in which the wax pattern 2 coated with the boron nitride-containing investment material 11 as described above is set in accordance with a conventional method.
was buried.

After curing and drying, this was heated to 700° C. to incinerate the wax pattern 2 and sprue wire 3. In this way, 7jI
A lost wax mold 7 for a tooth crown and a sprue 8 as shown in Jz diagram (d) were formed.

On the other hand, CaO24% by weight, Al2O31% by weight,
A glass melt having a composition of 575% by weight of P2O was melted at 1250°C to prepare a glass melt.

As shown in FIG. 2(e), this glass melt 9 is passed through a sprue 8 and cast into a lost wax mold 7 for making an i crown using a hot centrifugal FJ machine, and then the mold is placed in an electric furnace at 680°C.
After holding the mold for 3 hours to perform crystallization treatment, the investment material was broken and the molded body was taken out. And as shown in Figure 2(f), the line A-A
The sprue 8 was cut off from the sprue 8 to obtain the crown lO shown in FIG. 2(g).

The calcium phosphate-based crystallized glass tooth crown obtained in this way has a smooth surface with a gloss even without polishing, and when attached to the dental plaster mold used to create the wax pattern, it fitted very well. Indicated. The obtained crystallized glass dental crown had a compressive strength of 4000 kg/crn' and a bending strength of 1700 kg/cm'.

Comparative Example A crystallized glass dental crown was obtained in the same manner as in Example 2, except that the investing material containing boron nitride was not applied on the wax pattern. The crown had a white, rough surface and was poorly compatible with the dental plaster cast 1.

[Effects of the Invention] As described above, according to the present invention, since the reaction between the molten glass and the mold material can be suppressed, a calcium phosphate glass molded body with good surface properties and high dimensional accuracy can be obtained.

[Brief explanation of the drawing]

Figure 1 (a) is a cross-sectional view of the stainless steel mold, Figure 1 (b)
is also a vertical sectional view. FIG. 2 is a diagram showing an example, in which (a) is an explanatory diagram of creating a wax pattern for making a dental crown, (b) is an explanatory diagram showing the structure of a wax pattern, a sprue line, and a rubber cone, and (C ) is an explanatory diagram of the embedded state of the wax pattern, (d) is an explanatory diagram showing the configuration of the lost wax mold and sprue, (e) is an explanatory diagram of the casting state of glass melt, and (f) is a tooth crown with one sprue. Figure, same (g
) is a diagram of a tooth crown. 1--Gypsum mold 2-M-Wax pattern 3--Sprue wire 4-M-Rubber cone 5-M-Slurry investment material 6--Metal ring 7--Lostwax for making a crown 7x type 8-11 Blue 9-m-Glass melt 1G--1 dental crown 11--Investment material layer containing 1% by weight or more of mono-boron nitride 1
Figure 2 Figure 10 (Q) Inner closing

Claims (2)

[Claims] (1) Calcium phosphate, characterized in that a reaction suppression layer containing 1% or more boron nitride is provided on the surface of the mold in a molding method in which a melt containing 90% by weight or more of calcium phosphate is poured into a mold, cooled and solidified, and then molded. A method of forming quality glass. (2) The method for forming calcium phosphate glass according to claim 1, wherein the thickness of the layer containing boron nitride is 10 μm or more.