JP2880908B2 - Pearl manufacturing core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pearl-producing nucleus and a method for producing the pearl. More particularly, the present invention relates to pearls such as pearl oysters and pearl oysters which are excellent in physical strength and workability. The present invention relates to a pearl production core (or imitation pearl core) which is excellent in affinity for shellfish, and which is excellent in color tone, color, and luster of a film when a pearl shell forms a film, and a method for producing the same.

[0002]

2. Description of the Related Art Cultured pearls are produced by inserting nuclei into mother oysters such as pearl oysters and culturing them to form a nacre around the nuclei. Natural shells, such as mud shells that inhabit the Mississippi River in the United States, are cut into dice and then processed into spherical shapes.

[0003] However, in this method, since the thickness of the shell is not constant, it is difficult to obtain a product having a uniform particle size, and it is difficult to obtain a product having a high product value with a diameter of 7 mm or more. Furthermore, in order to obtain good-quality pearls, it is necessary that the spheres have a plain white and glossy sphere, but many shells of mussels have a streaky colored layer, Along with the shape problem,
There was a problem that the processing yield from shells was low. More recently, the depletion of natural resources has led to concerns about the availability of shells suitable for pearl production nuclei, and there has been a demand for excellent artificial pearl production nuclei that are easy to produce and that can be obtained stably. Have been.

[0004] Under such circumstances, various methods for producing artificial pearl production nuclei using various organic and inorganic materials and resins have been proposed. For example, JP-A-60-25
No. 9135 discloses that 20 to 100% by weight of a powder selected from pearl powder, coral powder and crustacean shell powder having a particle size in the range of 0.1 to 105 μm, and a particle size in the range of 1 to 100 μm. 0 to 80% by weight of calcium carbonate and 0 to 20
% By weight of an inorganic pigment.
A method for cultivating colored pearls using a molded body pressed at 00 ° C. as a core is disclosed. Also, JP-A-63-219325
Japanese Patent Application Laid-Open Publication No. H11-157, discloses a molded article comprising calcium carbonate, a synthetic resin, and a pigment, wherein the linear expansion coefficient of the molded article is 0.5 × 1.
A method for culturing pearls using artificial nuclei such as in the range of 0 ^{-5 to} 2.0 × 10 ^-5 / ° C. is disclosed. JP-A-3-21
No. 9817 discloses that a hot isostatic press uses 800
A method for cultivating pearls using a molded body containing hydroxyapatite molded at a temperature of 1500 kg / cm ² for 2 hours at a temperature of 1,200 kg / cm ² is disclosed. Japanese Patent Application Laid-Open No. 4-108326 discloses a matrix 50 containing calcium carbonate.
A cultured pearl core material comprising 90% by weight and the balance of glass and unavoidable impurities is disclosed. JP-A-4-1172
No. 28 discloses that a raw material powder mixture having a maximum temperature of 1000
Heat treatment at a temperature condition of ~ 1100 ° C to precipitate crystals of fluorophlogopite, and the obtained heat-treated product has an average particle size of 5 µm.
After pulverizing so as to be as follows, one molded into a desired shape is sintered at 1100 to 1300 ° C., and the obtained sintered body is processed by a hot isostatic press and polished to form an artificial pearl nucleus. A method for producing the resulting artificial pearl nucleus is disclosed. JP-A-4-218324 discloses that a pearl nucleus obtained by molding a calcium phosphate compound into a sphere is nucleated in a pearl shell,
A method of causing the pearl mussel to form a pearl is disclosed. JP-A-4-325040 discloses that a kneaded material is prepared by adding an organic binder to an inorganic powder and kneading the mixture by heating, and thereafter, molding is performed by an injection molding method using the kneaded material. A method for producing a pearl nucleus by degreased and sintering a molded body is disclosed. JP-A-4-356146
Japanese Patent Laid-Open Publication No. H11-175686 discloses a method of forming a pearl nucleus in a pearl mussel by nucleating a pearl nucleus of spherically formed antibacterial calcium phosphate. JP-A-5-15274
Japanese Patent Application Laid-Open Publication No. H11-157, discloses a method in which a pearl mother nucleus obtained by molding a composite material containing a calcium phosphate-based compound in a resin into a sphere is nucleated into a pearl shell to form a pearl. JP-A-5-64524 discloses a pearl nucleus characterized in that at least the surface layer is a resin layer containing polylactic acid or a derivative of polylactic acid. JP-A-5-12
No. 3075 proposes a pearl nucleus in which a stone having a specific gravity of 2.5 to 3.0 and a hardness of 3 to 5 (Mohs hardness) is formed into a predetermined spherical shape.

[0005] By the way, the following characteristics are required for the material of the nucleus for the production of cultured pearls. 1) The specific gravity should be around 2.75, which is close to the specific gravity of pearls. 2) White and translucent without color unevenness. 3) The structure is dense and uniform at the same time. 4) The hardness is appropriate (the Mohs hardness of the pearl is 3 to 4). 5) The coefficient of thermal expansion is 5 × 10 ⁻⁶ or more.
1.5 × 10 ^-5 . 6) No harmful components are eluted by seawater.

However, all of the materials proposed so far have advantages and disadvantages, and none are satisfactory in all aspects.

The present invention has developed a pearl manufacturing core which satisfies all of the above-mentioned required characteristics, and is particularly close to the specific gravity of pearls, has excellent physical strength, has no color unevenness, is translucent in white, and has a large sphere diameter. It is an object of the present invention to provide a pearl-producing nucleus which can be molded with high dimensional accuracy even if it has a nucleus and a method for producing the same.

[0008]

Means for Solving the Problems The present inventors have studied various materials for pearl manufacturing nuclei, and found that a specific amount of an inorganic filler was added to a specific thermosetting resin, followed by heating and kneading. By preparing a kneaded product, pulverizing, then, if necessary, forming a tablet, performing compression molding, transfer molding, injection molding, etc., and polishing the obtained molded body to obtain a physical strength. Excellent, specific gravity is 2.0
It has been found that an artificial pearl nucleus having a characteristic very close to that of a natural pearl nucleus and a method for producing the same can be provided. Reached.

That is, the present invention relates to [A] (1) 10 to 90% by weight of an unsaturated polyester having a number average molecular weight of 3,000 or more, and (2) monomers or an unsaturated monomer capable of dissolving the unsaturated polyester. Molecule weight 500 ~ copolymerizable with saturated polyester
[B] An inorganic filler having a specific gravity of 2.5 or more based on 100 parts by weight of an unsaturated polyester resin comprising 90 to 10% by weight of 2,000 unsaturated oligomers.
An object of the present invention is to provide a pearl production core obtained by molding a resin composition obtained by blending parts by weight.

[0010] The present invention also provides the above-mentioned pearl-producing core, wherein the number average molecular weight of the unsaturated polyester is 5,000 or more.

Further, according to the present invention, the inorganic filler may be alumina, aluminum hydroxide, magnesium oxide, silica,
An object of the present invention is to provide the pearl production nucleus, which is at least one selected from the group consisting of titanium oxide, zirconium oxide, barium sulfate, zinc oxide, calcium carbonate, calcium phosphate, and hydroxyapatite.

Further, the present invention provides the above-mentioned pearl production core, wherein the amount of the inorganic filler used is 400 to 650 parts by weight.

The present invention also provides the above-mentioned pearl-producing core having a specific gravity of 2.0 to 3.3.

The present invention further relates to (A) (1) 10 to 90% by weight of an unsaturated polyester having a number average molecular weight of 3,000 or more, and (2) monomers or an unsaturated monomer capable of dissolving the unsaturated polyester. Molecule weight 500 ~ copolymerizable with saturated polyester
[B] An inorganic filler having a specific gravity of 2.5 or more based on 100 parts by weight of an unsaturated polyester resin comprising 90 to 10% by weight of 2,000 unsaturated oligomers.
A part by weight is uniformly kneaded while heating, and then the obtained resin composition is molded into a desired shape by transfer molding or injection molding to a specific gravity of 2.0 to 3.3. And a method for producing a pearl production core.

Hereinafter, the present invention will be described in more detail. The unsaturated polyester used in the present invention is a high-molecular-weight unsaturated polyester having a number average molecular weight of 3,000 or more, preferably 5,000 or more (hereinafter, when a monomer or unsaturated oligomer is used in combination, a resin is used. , But not for polyester alone). Such a high molecular weight unsaturated polyester has a number-average molecular weight of 3,3 while avoiding the danger of gelation observed in the production of the conventional unsaturated polyester, which has already been proposed by the present inventors. 000 or more (JP-A-3-220232 and JP-A-3-153719). These methods are summarized below.

These processes include an α, β-unsaturated polybasic acid (or anhydride) as one component, and optionally use a saturated or unsaturated polybasic acid (or anhydride) in combination with the polybasic acid. After esterification with a polyhydric alcohol, a necessary catalyst is added, and the degree of pressure reduction and temperature are selected to carry out a deglycol-reaction.

(A) Examples of the α, β-unsaturated polybasic acid (or anhydride thereof) include maleic anhydride and fumaric acid in practice. (B) Saturated or unsaturated polybasic acids (or their anhydrides) include those having a benzene nucleus, such as phthalic anhydride, isophthalic acid, terephthalic acid, and dimethyl terephthalate, and aliphatic cyclic polybasic. As an acid or an anhydride thereof, tetrahydrophthalic anhydride,
Methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, endmethylenetetrahydrophthalic anhydride, methylendmethylenetetrahydrophthalic anhydride, and hetic acid, and further, as aliphatic dicarboxylic acids, succinic acid, adipic acid, azelaic acid, sebacic acid, etc. can give.

The polyhydric alcohols used in combination with the above-mentioned polybasic acids include ethylene glycol, propylene glycol, 2-methylpropanediol 1,3, diethylene glycol, dipropylene glycol, 2,2-diethylpropanediol 1,3, Butanediol 1,3, butanediol 1,4, neopentyl glycol, pentanediol 1,5, hexanediol 1,6,1,4-cyclohexane dimethanol, and the following polyvalents which have a high boiling point and are difficult to exchange glycol: Alcohol can be used in a partially combined form. Hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, glycerin diallyl ether, trimethylolpropane mono or diallyl ether. Further, an alkylene monoepoxy compound can also be used. Examples thereof include ethylene oxide, propylene oxide, epichlorohydrin, phenylglycidyl ether, allyl glycidyl ether and the like.

The esterification in the first stage is carried out in a conventional manner at a temperature of 160 to 230 ° C. in an inert gas stream, and an acid value of 15
Hereinafter, desirably, the hydroxypolyester is synthesized substantially at 12 or less. At this time, the number average molecular weight needs to be 1,000 or more. The second step of the glycol removal reaction (transesterification reaction) is performed at a temperature of 170 to 220 ° C. in the presence of a catalyst under a high reduced pressure of 5 Torr, preferably 1 Torr or less. At this time, if the acid value exceeds 15, the deglycolization reaction is not sufficiently performed, and as a result, it becomes difficult to synthesize a desired high-molecular unsaturated polyester. As the catalyst, an organic compound of titanium can be used. Examples are tetrabutyl titanate, tetrapropyl titanate, and acetylacetonate of titanium. The amount used is 0.01 parts by weight or more, preferably 0.01 to 100 parts by weight, per 100 parts by weight of the hydroxy polyester.
It is 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight. In this way, a high molecular weight unsaturated polyester having a number average molecular weight of 3,000 or more is obtained. Unsaturated polyester obtained by conventional direct esterification method,
The number average molecular weight was about 1,000 to 2,500, and even if the number average molecular weight was attempted to be 3,000 or more, it was difficult to produce due to gelation.

Styrene is a typical monomer for dissolving the unsaturated polyester to form a resin.
Other examples include methyl methacrylate, vinyl toluene, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, and prepolymers of diallyl phthalate, diallyl isophthalate, and diallyl terephthalate.

The unsaturated oligomers having a molecular weight of 500 to 2,000 include, for example, the following types. (A) Allyl polyester in which the terminal group is an allyl group and the constituent unit of the oligomer is a polyester. (B) A vinyl ester resin obtained by reacting an epoxy resin with (meth) acrylic acid. (C) Urethane-acrylate or polyester-acrylate having at least one (meth) acryloyl group in one molecule, or (meth) acrylates of polyhydric alcohols. The mixing ratio of these monomers or unsaturated oligomers to the high-molecular unsaturated polyester is 9
0 to 10% by weight, preferably 80 to 20% by weight, the latter 1
It is 0 to 90% by weight, preferably 20 to 80% by weight.
When the blending ratio of monomers or unsaturated oligomers is 90
If the content is more than 10% by weight, it is difficult to cure, and it takes a long time to cure, and if the content is less than 10% by weight, the molded article has poor physical properties and is difficult to withstand drilling or the like.

In the present invention, an inorganic filler is blended with the unsaturated polyester resin described above. In order to obtain a specific gravity of the pearl production core of 2.0 to 3.3, the inorganic filler may be mixed with an inorganic filler. Specific gravity requires 2.5 or more. Such inorganic fillers include, for example, calcium carbonate, alumina, magnesium oxide, silica, titanium oxide, zirconium oxide, aluminum hydroxide, magnesium carbonate, barium sulfate, calcium sulfate, clay, kaolin, talc, mica powder, glass powder , Calcium phosphate, zinc oxide, hydroxyapatite and the like. Among these inorganic powders, alumina, aluminum hydroxide, magnesium oxide, silica, titanium oxide, zirconium oxide, barium sulfate, zinc oxide, calcium carbonate, phosphoric acid At least one member selected from the group consisting of calcium and hydroxyapatite is particularly preferable because of its affinity with pearl mussels and improvement in whiteness, transparency, and machinability of pearl-producing nuclei.

The mixing ratio of the above-mentioned inorganic filler is 300 to 70 parts by weight based on 100 parts by weight of the unsaturated polyester resin.
0 parts by weight, preferably 400 to 650 parts by weight. When the amount is less than 300 parts by weight, the miscibility with the unsaturated polyester resin is good, but the hardness as a pearl production core is lowered, and the machinability is reduced. Miscibility with resin decreases,
The uniformity of the dispersion of the inorganic filler is lowered, and the dispersion in quality is increased, which is not preferable.

Although the method for producing a pearl-producing nucleus of the present invention is not particularly limited, a preferred example will be described below. First, the above-mentioned unsaturated polyester resin and inorganic filler are uniformly kneaded while heating (a reactive diluent can be used in combination if desired). The heating temperature varies depending on the amount of the unsaturated polyester resin to be added.
It is about 0 ° C. Note that kneading is preferably performed using a heating roll or a heating kneader to which a shearing force is applied.
Subsequently, the kneaded material prepared by the heat kneading is formed into tablets or pellets using a pulverizer, a tablet machine or a pelletizer. Next, the tablet or the pellet is formed into a sphere having a desired size by transfer molding, injection molding, or the like, and polished. According to such a method, a pearl manufacturing nucleus can be easily manufactured, a product having a stable quality can be obtained, and an initial investment amount is small and a product can be manufactured at low cost. In the present invention,
In preparing the kneaded product, a catalyst for accelerating the curing of the unsaturated polyester resin, or a dye or pigment as a colorant can be added.

The pearl-producing nucleus of the present invention is capable of producing pearls of good quality with good yield by inserting and culturing the nucleus into mother oysters such as pearl oysters. Further, the pearl-producing nucleus of the present invention can be suitably used also as an artificial pearl nucleus by applying a paint for forming a pearl-like layer over several layers around the nucleus.

[0026]

The pearl production core of the present invention can be made to have a specific gravity close to that of pearls by blending an unsaturated polyester resin with a specific amount of an inorganic filler having a specific gravity of 2.5 or more, and the pearls having no color unevenness. A layer can be obtained, and molding can be performed with high dimensional accuracy even with a large sphere diameter. In addition, since a high-molecular unsaturated polyester is used, good physical strength is exhibited. Also, depending on the mixing ratio of the above components, specific gravity, transparency,
Gloss and color can be controlled. Moreover, by using the transfer molding method and the injection molding method at the time of molding, pearl nuclei having a large spherical diameter, which cannot be produced by the conventional pressure molding method, can be mass-produced in a short time with high dimensional accuracy. Also,
Conventional ceramic-based artificial pearl manufacturing nuclei have a sintering temperature in the range of 1000 to 1600 ° C. and a sintering time of about 1 to 4 hours. Molding can be performed in a short time under mild conditions of a temperature of 100 to 200 ° C. and a curing time of several minutes. Furthermore, the pearl-producing nucleus of the present invention has excellent affinity for pearl mussels, a dense and uniform tissue, good hardness and thermal expansion coefficient, and no elution of harmful components due to seawater.

[0027]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The number average molecular weight and weight average molecular weight were measured by GPC. The measurement conditions are shown below. Shodex GPC SYSTEM-11 (Showa Denko) Eluent CH ₃ COONa 5 mmol / hexafluoroisopropyl alcohol (HFIP) (1 liter) Column Sample column HFIP-800P HFIP-80M × 2 Reference column HFIP-800R × 2 Column temperature 40 ° C Flow rate 1.0 ml / min Detector Shodex RI STD PMMA (Shodex STANDARD M-75)

Example 1 Synthesis of High Molecular Weight Unsaturated Polyester (A) 300 g of 2-methylpropanediol 1.3 was placed in a 1-liter separable flask equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube. 407 g of dimethyl terephthalate and 1.4 g of tetraisopropyltitanium were charged, and a methanol removal reaction was carried out at 200 to 205 ° C. After methanol was no longer distilled, 88 g of maleic anhydride was added, and the mixture was heated at the same temperature under a nitrogen stream. After esterification to an acid value of 10.9, the apparatus was changed, and 0.4 g of phenothiazine and 0.4 g of phosphorous acid were added.
The deglycol-reaction was performed at 190 to 192 ° C. for 4 hours under reduced pressure of orr. The resulting high molecular weight unsaturated polyester (A) was pale yellow, slightly cloudy, slightly pine-like, and had a number average molecular weight of 7,900 and a weight average molecular weight of 45,700.

Production of molding material 100 parts by weight of unsaturated polyester (A), 55 parts by weight of a polyester of propylene glycol and terephthalic acid having an allyl ester group at a terminal (molecular weight: about 1,000, allyl resin manufactured by Showa Denko KK), diallyl 25 parts by weight of terephthalate, 3 parts by weight of dicumyl peroxide, barium sulfate (BF-20 manufactured by Sakai Chemical Co., Ltd., primary particle size: 0.03
μm) 760 parts by weight, 320 parts by weight of hydrated alumina (manufactured by Showa Denko K.K., Hydride H-31, average particle diameter 17 μm) and 9 parts by weight of zinc stearate are kneaded with a roll at 90 to 100 ° C. to form a molding material. [I] was obtained. 12mm diameter
Is heated to 160 to 165 ° C., and a transfer molding machine with an output of 4 t is used. The mold clamping pressure is 150 kg / cm ² , the injection pressure is 140 kg / cm ² , and the temperature is 150 ° C.
After injection into a 12-cavity mold having a diameter of 12 mm, the mold was held for 3 minutes, opened and demolded. A slightly greenish white pearl nucleus with a diameter of 12 mm and a transparent feeling was obtained. The specific gravity was 2.7.

Example 2 Synthesis of High Molecular Weight Unsaturated Polyester (B) 300 g of 1,4-cyclohexanedimethanol and ethylene glycol were placed in a 2-liter separable flask equipped with a stirrer, a distillation condenser, a thermometer and a gas inlet tube. 14
0 g, 398 g of isophthalic acid and 0.9 g of tetraisopropyl titanate were esterified in a nitrogen stream at 200 to 205 ° C. to an acid value of 9.2, and 175 g of fumaric acid was added.
1 g of antimony trioxide, 0.5 g of phenothiazine, and 0.5 g of phosphorous acid were added, the equipment was changed, and finally 0.8 Torr was added.
After performing a deglycol-reaction for 5 hours at 190 to 192 ° C. under reduced pressure of r, 20 g of trimellitic anhydride was added and reacted. Obtained high molecular weight unsaturated polyester (B)
Is a slightly turbid tan, with a number average molecular weight of 8,70
0, the weight average molecular weight was 65,700, and the acid value was 25.4.

Production of molding material 50 parts by weight of unsaturated polyester (B) and 50 parts by weight of styrene were added to make a uniform liquid, and barium sulfate (BF-1 manufactured by Sakai Chemical Co., primary particle size: 0.05 μm) 380 Parts by weight, hydrated alumina (Heidilite HS-, manufactured by Showa Denko KK)
180 parts by weight of 320ST, average particle diameter of 18 μm), 1 part by weight of magnesia, 2 parts by weight of t-butyl perbenzoate, and 5 parts by weight of zinc stearate are kneaded in a kneader at 40 to 45 ° C. After aging for days, a light gray white solid molding material [II] was obtained. Molding temperature 150-1
Using a spherical mold with a diameter of 9.3 mm at 55 ° C and 16 pieces,
Example 1 A material was preheated to 80 ° C. by a high frequency preheater, and
Transfer molding was performed in the same manner as described above. A slightly yellowish green nucleus for the production of pearls having a diameter of 9.2 mm was obtained. The specific gravity was 2.8.

Examples 3 to 7 Synthesis of high molecular weight unsaturated polyester (C) Neopentyl glycol 11 was placed in a 50-liter reactor equipped with a stirrer, a fractionating condenser, a thermometer and a gas inlet tube.
kg, 11.6 kg of isophthalic acid, 200-205
C., esterification in a stream of nitrogen to an acid value of 28.1,
After adding 2.7 kg of maleic anhydride, 25 g of tetraisopropoxytitanium and 25 g of antimony trioxide to an acid value of 11.4, 12 g of phenothiazine and 12 g of phosphorous acid were added, and finally 185 under reduced pressure of 0.6 Torr. A deglycol reaction was performed at ~ 190 ° C for 6 hours. A light yellowish brown, slightly turbid, high molecular weight unsaturated polyester (C) having a number average molecular weight of 7,900 and a weight average molecular weight of 32,400 was obtained.

Production of molding material 30 parts by weight of a polyester of dimethyl terephthalate having a terminal allyl group and neopentyl glycol (molecular weight: about 1,000, allyl resin manufactured by Showa Denko KK) was added to 70 parts by weight of the unsaturated polyester (C). 2 parts by weight of dicumyl peroxide and 5 parts by weight of zinc stearate are kneaded with inorganic fillers shown in Table 1 below at 110 to 115 ° C. to obtain a molding material [III], which is specified in JIS K-6911. Molding die and 24-millimeter diameter 8.2m
Using a m-shaped spherical mold, a test piece and a pearl production core were each molded. Table 1 shows the appearance, physical properties and specific gravity of the obtained test pieces.

[0035]

[Table 1]

From Table 1, it can be seen that the optimum appearance, physical properties and specific gravity as pearl production cores were obtained.

[0037]

The pearl-producing nucleus of the present invention can obtain good physical strength by blending a high-molecular-weight unsaturated polyester with a specific amount of an inorganic filler, and has a specific gravity close to that of pearls. Thus, a nacre without color unevenness can be obtained, and molding can be performed with high dimensional accuracy even with a large sphere diameter. Furthermore, the pearl-producing nucleus of the present invention has excellent affinity for pearl mussels, a dense and uniform tissue, good hardness and thermal expansion coefficient, and no elution of harmful components due to seawater.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Uzura, 350-6 Kodome, Ikaruga-cho, Ikoma-gun, Nara Prefecture, Japan (72) Inventor, Tomio Jinzaki No. 316, Ogawacho, Ibaraki-shi, Osaka (56) 6-22662 (JP, A) JP-A-48-52594 (JP, A) Japanese Patent Publication No. Sho 31-6073 (JP, B1) Japanese Patent Publication No. Sho 30-1329 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) A01K 61/00

Claims (6)

(57) [Claims] 1. [A] (1) 10 to 90% by weight of an unsaturated polyester having a number average molecular weight of 3,000 or more, and (2) a monomer capable of dissolving the unsaturated polyester or the unsaturated polyester. Copolymerizable unsaturated oligomers having a molecular weight of 500 to 2,000 90 to
[B] An inorganic filler having a specific gravity of 2.5 or more, based on 100 parts by weight of the unsaturated polyester resin comprising 10% by weight.
A pearl production core obtained by molding a resin composition obtained by blending parts by weight. 2. The pearl production core according to claim 1, wherein the number average molecular weight of the unsaturated polyester is 5,000 or more. 3. The at least one inorganic filler selected from the group consisting of alumina, aluminum hydroxide, magnesium oxide, silica, titanium oxide, zirconium oxide, barium sulfate, zinc oxide, calcium carbonate, calcium phosphate and hydroxyapatite. The pearl-producing nucleus according to claim 1 or 2, which is a seed. 4. The amount of the inorganic filler used is 400 to 65.
The pearl production core according to any one of claims 1 to 3, wherein the pearl production core is 0 parts by weight. 5. The pearl manufacturing nucleus according to claim 1, wherein the specific gravity is from 2.0 to 3.3. 6. [A] (1) 10 to 90% by weight of an unsaturated polyester having a number average molecular weight of 3,000 or more, and (2) a monomer capable of dissolving the unsaturated polyester or the unsaturated polyester. Copolymerizable unsaturated oligomers having a molecular weight of 500 to 2,000 90 to
[B] An inorganic filler having a specific gravity of 2.5 or more, based on 100 parts by weight of the unsaturated polyester resin comprising 10% by weight.
A part by weight is uniformly kneaded while heating, and then the obtained resin composition is molded into a desired shape by transfer molding or injection molding to a specific gravity of 2.0 to 3.3. , A method of producing a nucleus for pearl production.