JPH0311005A - Production of porcelain for dentist containing yellowing-preventing sb2o3 - Google Patents

Abstract

PURPOSE:To effectively prevent yellowing of porcelain for dentist especially burned, particularly repeatedly burned in the presence of silver by heat-treating porcelain powder containing specific amount of antimony trioxide at specific temperature condition. CONSTITUTION:Porcelain powder containing 0.1-2.0wt.% antimony trioxide (Sb2O3) as yellowing-preventing agent is heat-treated in a range from maximum temperature without generating of softening and fusing of said powder (usually about 400-800 deg.C) to a temperature 300 deg.C lower than the maximum temperature, preferably a temperature 200 deg.C lower than usual softening temperature of porcelain as 600-800 deg.C to afford a porcelain for dentist capable of forming a porcelain layer having fixed color tone without generating yellowing phenomenon in any condition such as baking and burning to the surface of metal especially containing silver, repeated burning at said condition, post-soldering using gold solder or burning in a furnace polluted with silver.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing dental porcelains, particularly those used in the presence of Ag.

[Prior Art and Issues] Dental porcelain has a so-called yellow color that occurs when it is baked on a metal frame containing a specific metal component (particularly Ag) or when fired in an environment that coexists with that metal. There is a strange phenomenon. This yellowing phenomenon.

This is a fatal problem in dental porcelain materials that adjust the color tone after firing, and various countermeasures have been taken in the past, but none of them have been satisfactory. Problems with conventional measures are discussed below.

The method of placing carbon honeycombs and carbon plates together in the furnace reduces yellowing caused by silver to some extent. However, not only cannot it be completely prevented, but also the reducing action of CO gas fades the coloring of the porcelain due to the oxide and generates bubbles in the porcelain.

For baking metal frames, etc., a method has been proposed in which a metal conditioner is applied to the surface in advance. However, baking porcelain can reduce its strength. Additionally, silver evaporates from inside the untreated metal frame and from the silver-contaminated furnace, making it impossible to completely prevent yellowing of the porcelain. Moreover, in this method, Au-Pd-A
Crowns made of g-alloy or Pt-Au alloy (containing about 10% silver) do not prevent yellowing of the porcelain due to the silver they contain.

When a metal frame is made using a semi-pleasant alloy that does not contain silver, there is no yellowing of the baked porcelain. However, if a cast crown containing silver is subsequently soldered to this, yellowing at the boundary cannot be avoided. Moreover,
Post-soldering to a metal frame that does not contain silver results in weak bonding strength.

There are many cases of damage occurring within the oral cavity. For this reason, many people choose to bake porcelain on silver-containing alloys instead of turning a blind eye to yellowing.

Furthermore, recently, a porcelain material containing a nitric acid compound has been proposed (Japanese Patent Laid-Open No. 83-310805). but.

Clouding may occur after firing.

In addition, 1) yellowing cannot be sufficiently prevented as the porcelain is normally subjected to repeated firing. That is, although it is effective in preventing yellowing during the first firing, since the nitric acid compound is dissipated by the firing, it has little effect on subsequent firings, often resulting in yellowing.

[Means and effects for solving the three problems] Therefore, the present invention employs the following means to solve the problems. Antimony trioxide (Sb) as an anti-yellowing agent
20. ) from the maximum temperature at which the powder does not soften and fuse and that temperature 3.
A method for producing dental porcelain, characterized by heat treatment at a temperature of 0.000C or lower.

When porcelain (glass) yellowed by silver is heated at high temperatures (about 1200°C), the yellow color disappears and it becomes transparent. or.

When this transparent porcelain is reheated at a low temperature (about 800°C), it turns yellow again. This phenomenon is thought to be due to the fact that Ag ions at high temperatures turn into Ag colloids at low temperatures and develop color. However, a certain amount of 5bz in the porcelain
By containing Oa.

Some kind of oxidation effect works, and the silver diffused into the porcelain becomes Ag.
It is thought that yellowing can be prevented by allowing it to exist stably as an ion. In addition, by a prescribed heat treatment, the glass particle surface is inactivated and diffused Ag (particularly Ag, o
) is prevented from being adsorbed.

It is believed that yellowing can be prevented even more reliably.

The amount of sb, o is 0.1 to 2.0%. 0.1%
If it is less than 2.0%, the effect of preventing yellowing cannot be obtained, and if it exceeds 2.0%, the thermal expansion value of the porcelain fluctuates, and baking on metal frames sometimes becomes a problem. Preferably it is 1.0%.

Glass frit constituting the porcelain includes dental porcelain and 1. It can be applied to commonly used compositions.

For example, 810□55~65%, N120s 15~
Examples include those having a basic composition of 25%, 2Qg to 10%, Na, 08 to 12%. 1^, 2A, as necessary.
311.4B group oxides such as LI02. CaO, M
gO, B2O3, 5n02. I! Transfer metal oxides such as TiO2, ZnO, Zr5104, etc. are blended.

Also, as for the coloring agent, commonly used ones 9 such as Co
, Cr, Mn, fiJl, Fe, V, Pr
Each oxide or a mixture thereof can be used. It is preferable to avoid pb. This is because there is a possibility that sb and o3 may form a spinel compound with 5b2o3, inhibiting its yellowing prevention effect, and on the contrary, sb and o3 may act as a coloring agent.

The addition of 5b20s to the glass frit is as follows: 5b20. It may be carried out by adding powder and using a ball mill or the like. The particle size of the 5b203 powder is about 5-101. Furthermore, when preparing glass frit by melting silica, alumina, and alkali carbonate to obtain a predetermined composition, 0.1 to 2% by weight of 5b2o may be added. Glass frit adjustment and 5b2o
, compounding can be done simultaneously. After that, Sb, 0. The blended glass frit is crystallized by heat treatment at a temperature higher than the softening temperature (usually 900° C.), and then crushed to about 20p.

Next, the Sb, O, and blended porcelain powder is heat treated in the predetermined temperature range. The reason why the upper limit is set as the maximum temperature at which the powder does not soften and fuse is because if the powder softens and fuses, the active fracture surface will be exposed when it is re-pulverized, making it impossible to obtain the desired effect. The maximum temperature without softening and melting is
Although it varies depending on the glass composition, it is located between the glass transition point and the softening point, and is usually within the range of about 400 to 800°C.

Also, the temperature is at least lower than the softening temperature, preferably 200°C lower than the normal softening temperature of porcelain, 600-800°C.
Lower temperatures are preferred. On the other hand, the lower limit is lower than the upper limit temperature by 30
The reason why the temperature was set to be 0°C lower was that even if the treatment was performed at a lower temperature, the effect of inactivating the powder surface could not be obtained. Further, the heat treatment time may take a long time if the temperature is low, or a short time if the temperature is high. It is recommended that the time be about 0.1 to 5 hours. If it is less than 0.1 hour, the anti-yellowing effect will not be sufficient, and if it is more than 5 hours, it is not bad, but it is wasteful. A sufficient and maximum yellowing prevention effect can be obtained by heat-treating preferably for 0.5 to 2.0 hours near the transition point.

The 5b203-containing porcelain thus obtained is deposited on a metal base material and subjected to repeated firing in the usual manner. This dental porcelain can be applied to any of opaque, body, enamel, and translucent porcelains, and is also effective as a margin porcelain.

[Example] (Example A) Chemical components are 8102 in weight ratio; 85.8%, Aj!
20. ;15.0%, K, Q, 8.1%,
Na2O; 10.5%, transition point; 525°C, 2 particle size;
A predetermined amount of 5b2o having an average particle size of 5-5 was added to a glass frit of 200 mesh or less.

Next, this mixture was heat-treated at 900° C. for 2 hours, and then ground into 200 meshes or less in a ball mill. Then,
A porcelain material was obtained by heat-treating this powder at a predetermined temperature and time (sample N [Ll, 2, 3.4).

In order to perform a yellowing test, the obtained porcelain was pressed in a mold to create a disk with a diameter of 12 fins and a thickness of 2 am.
mg of pure silver powder was placed on it, and it was fired under the following various firing conditions to check for yellowing. For comparison, 5bzO
s was not added at all (sample N11L5, 6.7
) and domestically produced Company A products, which are representative commercially available porcelain materials (8 samples)
, products from 8 West German companies (Sample Demon 9).

A similar disk was prepared using a product from US company 0 (sample K10) and similarly examined for yellowing.

The firing conditions were as follows.

■) Place silver powder on the center of the disk and fire at 920°C, which is the standard firing temperature for porcelain.1 2) Place silver powder on the center of the disk and fire at the above standard temperature 5 times.

3) Assuming firing in a furnace contaminated with silver, from 2 discs to approximately 5
Place silver powder around the amM area and fire.

4) JI812 alloy plate (50% heg, 14 angle,
A disk was placed on top of C1.6u thick) with alumina powder interposed therebetween and fired.

The obtained results are also shown in Table 1.

Part 1 table - Comparative example O: No yellowing Δ: Slight yellowing ×; Significant yellowing l) The softening temperature of each sample is approximately 700℃ As is clear from Table 1, the comparative example sample kg.

9. IO turned yellow under each of the above firing conditions. On the contrary,
Example sample Na2.5bzOs containing a predetermined amount and subjected to a predetermined heat treatment. Samples a and 4 did not show yellowing under all conditions.

Also, from the results of sample N11L1, 5b20. It was also confirmed that if the amount is less than a predetermined amount (0.1 wt%), the anti-yellowing effect cannot be sufficiently exhibited.

Furthermore, from the results of Samples 5 and 6.7, it was confirmed that when no l5b2o3 was added, the anti-yellowing effect could not be exhibited, especially if the heat treatment temperature was low or the heat treatment time was insufficient.

(Example B) E-υ exhibits the most yellowing among commercially available semiprecious alloys
(0.5%Pt-58%Pd-29%Ag) was used to fabricate a metal frame with a single crown and double bridge, and the porcelain of each sample (k2, 3.4) used in Example A was built up. Fired.

This baked metal frame and a crown of Au--Pd--Ag alloy were brazed with metal (containing Ag) in a furnace. The degree of yellowing of the porcelain layer after firing and post-soldering was investigated, and the results are shown in Table 2.

(Margins below) Middle Comparative Example O: No yellowing
．． No. 10 all showed significant yellowing.

On the other hand, Example samples &2 and 3.4, which contain a predetermined amount of 5b203 and are subjected to a predetermined heat treatment, are all Ag
It was confirmed that no yellowing occurred at all even when baked onto frames containing Ag (single crown, bridge) or when soldered to crowns containing Ag.

Although dental porcelain has been described in one or more of the examples, similar favorable results can be obtained for ornaments and other glass compositions.

[Effects of the Invention] According to the present invention, by blending a predetermined amount of 5b203 and subjecting it to a predetermined heat treatment, the surface of a metal containing silver in particular is baked and fired repeatedly under this condition.

A porcelain layer having a predetermined color tone can be formed without any yellowing phenomenon under any conditions such as post-burning using gold lacquer or firing in a furnace contaminated with silver. In particular, 5
b20. Since it remains even after firing, it can effectively exhibit its yellowing prevention effect even if it is repeatedly fired as a dental porcelain.

still.

Other problems such as clouding do not occur either.

Claims (1)

[Claims] Antimony trioxide (Sb_2O_3
) A dental porcelain powder containing 0.1 to 2.0% by weight of porcelain powder is heat-treated within a range between the maximum temperature at which the powder does not soften and fuse and a temperature 300°C lower than that temperature. Method of manufacturing wood.