JP3047047B2 - Nuclear material for cultured pearls and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is excellent in workability, chemical resistance and heat resistance, has excellent affinity with pearl mussels such as pearl oysters, geese, mussels and crows, and has a film formed thereon. The present invention relates to a cultured pearl core material having excellent color tone, color and luster of a coating film, and a method for producing the same.

[0002]

2. Description of the Related Art Cultured pearls are obtained by inserting an object that becomes a pearl nucleus into a pearl oyster, culturing the pearl, and forming a film on the surface of the nucleus. In general, as such a nuclear body, a small spherical body obtained by cutting and polishing a natural shell such as a mussel or a fool mussel is in practical use.

[0003] The core material composed of the natural shell is used for producing a small spherical body by cutting and polishing.
Alternatively, there is a problem that cracks or defects are likely to occur when performing drilling or the like for decorative articles after obtaining cultured pearls. In addition, natural shells have an uneven streak pattern in the tissue, and the effect of the stripe pattern remains even after processing as a nuclear object, causing uneven color tone when a film is formed on the surface of the nuclear object. There is a problem that it is easy to occur. Furthermore, natural shells have a maximum diameter of 12
It can only manufacture nuclear objects up to mm. There is also a limit in resources. In addition, there is a problem that heat resistance and chemical resistance during the heating chemical treatment after the formation of the film are poor.

[0004] For the purpose of solving these problems of natural shells, many proposals have been made on artificially cultured pearl nuclear material.
259135 and JP-A-61-25428.

JP-A-60-259135 discloses that 20 to 100% by weight of powder such as pearl powder, coral powder and shell powder having a particle size of 0.1 to 105 μm and calcium carbonate having a particle size of 1 to 100 μm A method for cultivating colored pearls using a molded body having a diameter of 20 mm or less as a core body obtained by pressing a material obtained by mixing 80% by weight and an inorganic pigment at 0 to 20% by weight at a temperature of 400 to 1500 ° C. It has been disclosed. The cultured pearl nuclear material disclosed in the publication has the advantage that a large-diameter nuclear material that cannot be obtained with natural shells is obtained, but it is difficult to mass-produce because it is manufactured by a hot press method. , It takes a long processing time because there is a lot of processing margin when forming into the shape of the core body after sintering, the probability that cracks and defects occur during this forming is high, and when calcium carbonate is contained Has the problem that it is necessary to sinter at high pressure to control the thermal dissociation of calcium carbonate.

On the other hand, Japanese Unexamined Patent Publication (Kokai) No. 61-25428 discloses a cultured pearl made of a free-cutting crystallized glass obtained by incorporating a large amount of a calcium compound such as calcium silicate or calcium phosphate or a magnesium compound in a glass and hardening the glass. A core material is disclosed. Although the core material disclosed in the publication has the advantage of being excellent in chemical resistance and workability, it has low affinity with pearl mussels, and when inserted into the body of pearl mussel, pearl mussel is There is a problem that a nuclear object is ejected due to a rejection reaction, and the pearl oysters themselves are more likely to die.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems. Specifically, the present invention has a hardness and strength suitable for workability and a heat resistance. And to provide a cultured pearl core material having excellent chemical resistance, excellent affinity with pearl clams, and excellent color tone, color, and luster of a finished pearl coating, and a method for producing the same. It is the purpose.

[0008]

Means for Solving the Problems The present inventors have studied for the purpose of obtaining a cultured pearl core material having excellent affinity with pearl mussels and excellent hardness and strength with excellent workability. Based on the following findings, the present invention has been accomplished.

First, from the viewpoint of affinity with pearl mussels, it is desirable that the cultured pearl nucleus material be the same as that of natural shells, that is, it contains calcium carbonate as a main component.
In the case of forming a dense and high-strength sintered body containing calcium carbonate as a main component, it is necessary to perform high-temperature sintering or pressure sintering in the air. When the sintered body obtained by the former method is used as a core material for cultured pearls, water-soluble calcium oxide is generated,
Increase the mortality rate of the mother pearl oyster itself. On the other hand, in the latter method, for example, a pressure of 300 kg / cm ² , 1300 ° C.
It is difficult to obtain a dense sintered body even under the above conditions. Further, even if a dense sintered body is obtained, the processing cost of the core object increases.

Second, powders of calcium phosphate, silicon oxide, and aluminum oxide; or apatite, silicon oxide, and aluminum oxide are mixed in an organic solvent or pure water and sintered to obtain phosphorus in addition to calcium phosphate or apatite. It was found that aluminum oxide was formed. Furthermore, the present inventors have found that aluminum phosphate has the effect of promoting the sintering of these sintered bodies and improving the bonding strength of the crystal grains. They have been found to be equivalent; and that the resulting sintered body is dense and has excellent workability. In addition,
In this case, silicon oxide does not directly contribute to improvement of sinterability and strength, but P ₂ O ₅ —SiO ₂ —Al ₂ O
₃ pseudo ternary is P ₂ O ₅ -Al ₂ O ₃ tends to form a low melting eutectic than binary system, since promote the formation of aluminum phosphate, an important component for the present invention.

That is, the cultured pearl core material of the present invention comprises a sintered body having the following composition. (1) 70 to 96% by weight of a matrix composed of calcium phosphate and / or apatite; and (2) selected from a compound containing P, Al and O, a compound containing P, Si and O, silicon oxide and aluminum oxide. Skeleton 4 containing at least one kind
30% by weight.

The matrix comprises, for example, at least one of calcium phosphates represented by tribasic calcium phosphate, dibasic calcium phosphate, monobasic calcium phosphate and calcium metaphosphate; and apatites represented by hydroxyapatite, carbonate apatite and chlorapatite. Of these, tribasic calcium phosphate and / or hydroxyapatite are preferred. As the tribasic calcium phosphate, β-type, which is formed at a high temperature and is easy to produce and has excellent strength, is preferable to α-type having low hardness, and β-type It is particularly preferable to use calcium phosphate containing calcium triphosphate as a main component and hydroxyapatite, since they are excellent in workability as a pearl core material and biocompatibility with pearl oysters.

The skeleton refers to a substance other than the matrix in the cultured pearl core material. Specifically, for example, it contains silicon oxide such as silicon monoxide and silicon dioxide; aluminum oxide represented by α-type, β-type and γ-type; P, Al and O represented by aluminum phosphate (AlPO ₄ ). Compound; silicon phosphate (Si
₃ PO ₄ ), and compounds containing P, Si and O. Among them, in particular, when it is composed of silicon dioxide and a compound containing P, Al and O such as aluminum phosphate, it is effective in suppressing the transfer of β-type tricalcium phosphate to α-type, Is preferred because of its excellent bondability and the fact that various characteristics are stabilized and a sintered body excellent in quality can be obtained.

A compound containing P, Al and O as described above;
The compound containing P, Si, and O specifically refers to a compound formed by a reaction between aluminum oxide and a matrix, silicon dioxide and a matrix, or aluminum oxide, a silicon oxide, and a matrix.

[0015] The above-mentioned ratio between the matrix and the skeleton is such that the amount of the matrix in the cultured pearl nucleus material is 70 to 70%.
96% by weight, the amount of skeleton is in the range of 4-30% by weight. When the amount of the matrix is less than 70% by weight, the amount of the skeleton is relatively larger than 30% by weight, so that sintering becomes difficult, and further, the biocompatibility with the pearl oysters is reduced. Conversely, if the amount of the matrix exceeds 96% by weight, the amount of the skeleton is relatively less than 4% by weight, so that the strength is reduced and the workability as a cultured pearl core material is deteriorated. In addition, the cultured pearl core material of the present invention may contain impurities that are unavoidably mixed in addition to the above.

The cultured pearl core material of the present invention can be produced by applying a conventional powder metallurgy method, but it is particularly easy to produce by using the following production method. It is preferable because it is easy to obtain a product of stable quality and easily industrialized.

That is, the method for producing a core material for cultured pearls of the present invention comprises: (1) powder of calcium phosphate and / or apatite or a precursor thereof; a compound containing P, Al and O, P, Si and Mixing a compound containing O, at least one powder selected from silicon oxide and aluminum oxide; (2) forming the mixed powder into a green compact;
Baking at 100 to 1400 ° C .; and (3) firing the sintered body in an inert gas atmosphere at 1000 to 15 ° C.
Hot isostatic pressure treatment at 1000 atm and 1000 to 1400 ° C.

The raw material in the method for producing a cultured pearl core material of the present invention is, specifically, an average particle diameter of 0.1 to 3.0 μm.
Although it is preferable to use a powder of m, it can also be used as a precursor of calcium phosphate or hydroxyapitate, for example, in a state in which a calcium salt and ammonia are added to an aqueous solution of sodium phosphate or potassium phosphate and precipitated.

When a predetermined amount of the raw materials is mixed and pulverized, wet mixing is preferable in order to enhance the effects of mixing and pulverization, and it is preferable to use an organic solvent or pure water. Examples of the organic solvent include methanol, ethanol, isopropanol, butanol and the like.

In the case where the raw materials are mixed to form a green compact, there are conventionally used powder metallurgy forming methods, for example, a slip casting method, a powder press forming method using a mold, a centrifugal force forming method, and an injection molding method. A green compact can be formed using a molding method, an extrusion molding method, or the like.

From the green compact thus obtained, the sintering step and the hot isostatic pressure (HIP) step described above
The cultured pearl core material of the present invention can be obtained.

[0022]

In the cultured pearl core material of the present invention, the matrix acts to enhance the affinity with the pearl mussel, and the skeleton mainly maintains the strength and hardness in a well-balanced manner. Therefore, by combining the optimal amount of the matrix and the skeleton, sintering is promoted, densification, heat resistance, chemical resistance, the effect of increasing the surface roughness of the surface, and further, the surface color, color and Enables gloss control.

[0023]

The present invention will be described below with reference to examples. The present invention is not limited by the examples. In the examples,% represents% by weight.

Example 1 Commercially available β-tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ) powder (hereinafter referred to as βTCP) having an average particle diameter of 0.1 μm, and hydroxyapatite (Ca) having an average particle diameter of 0.1 μm
₁₀ (PO ₄ ) ₆ (OH) ₂ ) powder (hereinafter referred to as HAP) silicon dioxide powder having an average particle diameter of 0.3 μm, α-aluminum oxide powder having an average particle diameter of 0.3 μm, average particle diameter of 1.
0 μm calcium carbonate powder and magnesium oxide powder having an average particle size of 0.1 μm were used as raw materials. These were blended as shown in Table 1, and the blended powder was charged into a pot lined with a urethane resin together with alumina balls and methanol, and mixed in a ball mill for 48 hours.

Each of the mixed powders was dried at 100 ° C., and 8% of paraffin wax was added as a molding aid, and pressed at 1 ton / cm ² to form a green compact.
Dewax at 500 ° C in vacuum, 1300 ° C in air
For 1 hour. Then, the product of the present invention 1 to 7 shown in Table 1 was subjected to HIP treatment by holding at 1200 ° C. and 1000 atm for 1 hour in argon gas.
And Comparative products 1 and 2 were obtained. In addition, a product 8 of the present invention was obtained in the same manner as in the case of the product 2 of the present invention except that an aqueous solvent was used in the mixing step with the same composition as the product of the present invention. Furthermore, as a comparative product,
Similar to the cited prior art, the composition was as shown in Table 1, and after mixing, drying and pressing, it was held at 1300 ° C. for 1 hour and fired to obtain Comparative Products 3 and 4 shown in Table 1. . Also,
Mexican natural shellfish was used as a reference.

Inventive products 1 to 8 thus obtained and comparative product 1
~ 4 and each of the natural shellfish used as a reference,
The composition was confirmed by X-ray diffraction. The results are also shown in Table 1.

[0027]

[Table 1]

Next, the density, hardness, transverse rupture force and coefficient of thermal expansion of each sample in Table 1 were measured, and the color tone of the surface of the sintered body of each sample was observed. Table 2 shows the results.

[0029]

[Table 2]

Example 2 Of the samples shown in Table 1 of Example 1, the products 1 to 3 and 7 of the present invention, the comparative products 1, 2 and 4 and the reference product were each processed into a spherical body having a diameter of 6 mm. It was molded and the processing yield at this time was determined. The spheres thus formed were inserted into pearl oysters, and the affinity between each core material and the pearl oysters was examined. The affinity between the nuclear material and the pearl oysters was compared using the rate at which the pearl oysters died or the nuclear material discharged the pearl oysters. After the nacre layer was formed on the surface of the nuclear object, the surface condition and color tone of the film were observed. Furthermore, after a coating was formed on the surface of the core object, drilling was performed with a drill, and the processing yield during drilling was determined. Table 3 summarizes these results.

[0031]

[Table 3]

[0032]

The cultured pearl core material of the present invention has a higher processing yield rate when processed as a nuclear object and a decorative material after forming a film on the surface, as compared with a comparative product not according to the present invention. The yield rate when drilling is remarkably excellent. Furthermore, it has excellent biocompatibility with pearl mussels, which is determined from the sum of the mortality of the mussel when inserted into the pearl mussel to form a film on the surface and the discharge rate of the pearl mussel.

Further, the cultured pearl core material of the present invention has a remarkably excellent processing yield rate as compared with the core material of natural shellfish. In particular, in the case of the product of the present invention comprising a matrix mainly composed of β-type tricalcium phosphate, the biocompatibility with the pearl mussel is almost the same, and the color tone of the film surface after the film is coated is also almost the same. While the core material of natural shellfish has a high probability of causing color unevenness, the product of the present invention does not cause color unevenness when used as a core material.

As described above, the effect of the present invention is extremely remarkable.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tatsuya Sato 1-7-7 Tsukakoshi, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Tungaloy Co., Ltd. Examiner in a corporation Keiko Nagai (56) References JP-A-61-25428 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A01K 61/00

Claims (3)

(57) [Claims] 1. A cultured pearl core material comprising a sintered body composed of a matrix and a skeleton having the following composition. (1) 70 to 96% by weight of a matrix composed of calcium phosphate and / or apatite; and (2) selected from a compound containing P, Al and O, a compound containing P, Si and O, silicon oxide and aluminum oxide. Skeleton 4 containing at least one kind
30% by weight. 2. The matrix according to claim 1, wherein the matrix is composed of calcium phosphate mainly composed of β-type tribasic calcium phosphate and hydroxyapatite, and the skeleton contains a compound containing P, Al and O and silicon oxide. Nuclear material for cultured pearls as described. 3. A powder of calcium phosphate and / or apatite or a precursor thereof; and a compound containing P, Al and O, a compound containing P, Si and O, silicon oxide and aluminum oxide. Mixing at least one kind of powder to be obtained; (2) forming the mixed powder into a green compact;
Baking at 100 to 1400 ° C .; and (3) firing the sintered body in an inert gas atmosphere at 1000 to 15 ° C.
A method of hot isostatic pressure treatment at 1000 atm and 1000 to 1400 ° C., a method for producing a cultured pearl core material.