JP6618144B2 - Spherical calcium fluoride - Google Patents

Description

The present invention relates to spherical calcium fluoride. The present invention relates to spherical calcium fluoride spheroidized for the purpose of improving fluidity and filling properties when blended with a polymer material such as resin or plastic as a filler. The present invention relates to a resin composition filled with, for example, spherical calcium fluoride.

In general, various fillers are used for the purpose of improving physical properties and functions of plastics and rubbers. Calcium fluoride is an inorganic compound that is naturally produced as fluorite. It is an inorganic compound that can be easily obtained as synthetic calcium fluoride supplemented with the fluorine-containing compounds discharged in the chemical industry in the form of calcium salts. is there. Calcium fluoride has a refractive index of 1.43, a thermal conductivity of 10 W / mK, a thermal expansion coefficient of 24 ppm / K, and a dielectric constant of 6.8, which is excellent for a wide range of light from vacuum ultraviolet to infrared. Compared to silica and alumina, the Mohs hardness is low (Mohs hardness 4) and the mold is difficult to be damaged. For this reason, it is expected to be used in many applications in order to control the refractive index, thermal conductivity, thermal expansion coefficient, and the like of plastic and rubber.

However, it is not so common as a filler to be blended with the resin. For example, Patent Document 1 describes a filler in artificial marble, and Patent Document 2 describes a resin sliding member containing calcium fluoride. Thus, calcium fluoride as a resin filler is only slightly used for special applications.

In order to use it more suitably as a filler, it is necessary to improve the filling property, workability, and melt fluidity of the resin. In the case of calcium fluoride, it is spherical and has an appropriate particle size distribution, and there is little aggregation. It is demanded. For example, in Patent Document 3, 79% of crushed calcium fluoride is filled, but in addition to the necessity of surface treatment with a silane coupling agent, the resin is limited to a thermoplastic resin. In Patent Document 4, spherical or particulate calcium fluoride is filled in a polymer. However, the calcium fluoride exemplified therein has an aspect ratio of 1.8, which is hardly a spherical shape. Was insufficient.

Various methods for spheroidizing calcium fluoride have been disclosed.

For example, Patent Document 5 specifies a method of spheroidizing by wet pulverization in which mineral fine particles having a Mohs hardness of 5 or less are made into slurry, injected from both sides at an injection pressure of 100 to 200 MPa, and collided with each other. In the wet processing, in order to use as a filler, a drying step of the obtained particles is necessary, and the cost is further increased due to the use of a solvent. In Non-Patent Document 1, spherical calcium fluoride is synthesized by wet synthesis by the reaction of calcium chloride and ammonium fluoride. In addition to the disadvantages of the above wet treatment, particles of micron order that are suitably used as fillers are synthesized. Difficult to do.

In Non-Patent Document 2, a mixture of barium fluoride and calcium fluoride is spheroidized by a gas atomization method, but the effect on the filling property to the resin is not specified. Further, since the proportion of calcium fluoride is about 30% and the main component is barium fluoride, the solubility in water and the specific gravity are increased, which is not suitable as a filler to be filled in the resin. Furthermore, in Patent Document 6, there is a description that the atomizing method is possible. However, in addition to the details of the atomizing method and the description regarding the particle diameter and average circularity of the particles obtained by the atomizing method, it was spheroidized. The effect of is not specified.

Japanese Patent No. 4491619 Japanese Patent No. 5465270 JP 2003-40619 A Japanese Patent No. 5547644 Japanese Patent No. 4193913 JP 2002-188007 A

Asep Bayu Dani Nandyanto et al., Konapowderand Particle Journal, No. 29, 141-157, 2011 Malcolm K. Stanford, Tribology Transactions, 51, 829-834, 2008

An object of the present invention is to provide spherical calcium fluoride capable of preparing a resin composition having low viscosity and high fluidity even when the resin is highly filled.

(1) Spherical calcium fluoride having an average particle diameter of 1 to 50 μm and an average circularity of 0.90 or more.
(2) The method for producing spherical calcium fluoride according to (1), wherein the calcium fluoride raw material is produced by a powder melting method in which a raw material is passed through a high temperature region having a temperature equal to or higher than the melting point to be spheroidized.
(3) Manufactured by an atomizing method in which calcium fluoride is dissolved and the fluid is sprayed onto the molten metal dripped through the nozzle to disperse / spray the molten metal to rapidly solidify it into a sphere. (1) The manufacturing method of spherical calcium fluoride of description.
(4) Calcium fluoride is dissolved and the molten metal dripped through the nozzle is produced by an atomizing method in which the molten metal is dispersed and sprayed, rapidly solidified by spheronization by dropping the molten metal onto a rotating disk, The manufacturing method of spherical calcium fluoride as described in (1).

According to the present inventors, it is possible to provide spherical calcium fluoride capable of preparing a resin composition having low viscosity and high fluidity even when the resin composition is highly filled.

1 is a scanning electron micrograph of spherical calcium fluoride obtained in Example 1. FIG. The white line is the dimension. 2 is a scanning electron micrograph of the calcium fluoride used in the raw material of Example 1 and Comparative Example 8. FIG. The white line is the dimension.

The spherical calcium fluoride of the present invention has an average particle diameter of 1 to 50 μm and an average circularity of 0.90 or more. If the average particle size of the spherical calcium fluoride is less than 1 μm, the viscosity increases when mixed with the resin and the fluidity when the resin composition is poured into a mold or the like decreases, and if it exceeds 50 μm, the resin The filling property becomes worse. The average circularity of the spherical calcium fluoride is 0.90 or more, preferably 0.95 or more. When the average circularity is less than 0.90, the rolling resistance of the particles when mixed with the resin increases and the fluidity decreases.

Calcium fluoride which is a raw material of the present invention is not particularly limited, and natural fluorite pulverized may be used, or synthetic calcium fluoride may be used. Synthetic calcium fluoride is recovered as calcium fluoride by reacting hydrofluoric acid or fluoride ions discharged from processes such as chemical industry or semiconductor industry using fluorine compounds with calcium hydroxide or calcium carbonate. Calcium fluoride is also included.

Further, the purity of calcium fluoride which is a raw material of the present invention is preferably 75% by mass or more, and more preferably 90% by mass. If it is less than 75% by mass, the physical properties of calcium fluoride itself may be impaired, and impurities may increase. As for the average particle diameter of the calcium fluoride which is a raw material of this invention, 1-50 micrometers is preferable.

The method for producing spherical calcium fluoride of the present invention uses a powder melting method or an atomizing method.

The powder melting method is a method in which the raw material powder is passed through a high temperature region having a temperature equal to or higher than the melting point. In addition, the powder melting method described here includes a method in which the raw material powder is passed through a high temperature region having a temperature equal to or higher than the melting point without using a chemical flame or thermal plasma. , And a method of melting and spheronizing with its own surface tension.

In the powder melting method, particles obtained by granulating a powdery raw material with a spray dryer or the like, and particles adjusted by pulverizing a bulk material to obtain a desired particle size distribution can be used. Is put into a chemical flame or thermal plasma, a vertical tubular furnace or the like while suppressing agglomeration of particles, and melted in a chemical flame or thermal plasma, a vertical tubular furnace or the like. In addition, after preparing a dispersion of the raw material dispersed in a solvent or the like, the liquid raw material is sprayed into a chemical flame or thermal plasma, a vertical tubular furnace or the like using a nozzle or the like, and the dispersion medium is evaporated. This is done by melting.

In the powder melting method, the chemical flame refers to, for example, a flame generated by burning a combustible gas with a burner. As a source of chemical flame, it is only necessary to obtain a temperature higher than the melting point of calcium fluoride. For example, natural gas, propane gas, acetylene gas, liquefied petroleum gas (LPG), hydrogen or the like is used as a combustible gas. Can do. Air, oxygen, etc. are used in combination with combustible gas as a combustion-supporting gas. The size of the chemical flame, the temperature, etc. can be adjusted by the size of the burner and the flow rates of the combustible gas and the combustion-supporting gas. The supply amount of calcium fluoride as a raw material is preferably 0.01 to 10 kg / Nm ^{3 and} more preferably 0.05 to 2 kg / Nm ³ with respect to the total amount of combustible gas and combustion-supporting gas. 0.01 kg / Nm ³ is reduced and productivity low volume than, for many consisting of calcium fluoride than 10 kg / Nm ³ are aggregated, it becomes difficult to control the particle size. Unless otherwise specified, the flow rate is in normal notation. Further, oxygen, nitrogen, argon, carbon dioxide gas, and a mixed gas thereof are preferably used as the generation source of the thermal plasma. Further, a vertical tubular furnace or a tower kiln can be used as a melting source. The melting atmosphere of the furnace is preferably performed in an atmosphere that can be heated to the melting point of calcium fluoride or higher, the raw materials are not evaporated or decomposed, and the inside of the furnace is not significantly consumed. When the frame is not used, the supply amount of calcium fluoride as a raw material is preferably 0.01 to 10 kg per 1 Nm ³ of the atmospheric gas. When the amount is less than 0.01 kg, the productivity decreases, and when the amount exceeds 10 kg, calcium fluoride is aggregated, making it difficult to control the particle size.

In the atomization method, for example, a calcium fluoride raw material is dissolved using a crucible or the like, and a fluid such as water or gas is sprayed on the molten metal dropped through a nozzle at the bottom of the crucible, or the molten metal is applied to a rotating disk. It is a method of obtaining spherical calcium fluoride by dispersing and spraying the molten metal by dripping and rapidly solidifying it. As the atomizing method, any method such as a gas atomizing method, a centrifugal atomizing method, a hybrid atomizing method, a water atomizing method, a high-speed combustion flame atomizing method, or the like can be suitably used depending on a molten metal dispersion method.

In the gas atomization method, the molten metal temperature (melting temperature) is preferably 1500 to 2000 ° C. The diameter of the nozzle at the bottom of the crucible is preferably 0.5 to 3.0 mm. Examples of the gas include argon gas. The fluid injection pressure is preferably 0.8 to 10 MPa. In the centrifugal atomization method, the molten metal temperature (melting temperature) is preferably 1500 to 2000 ° C. The diameter of the nozzle at the bottom of the crucible is preferably 0.5 to 3.0 mm. The rotational speed of the disk is preferably 20000 rpm to 120,000 rpm. The diameter of the disk is preferably 20 mm to 100 mm. As the material of the disk, a material having a higher melting point than calcium fluoride and resistant to thermal shock, for example, Mo, W, Pt, SiC, BN or the like is selected.

In the case of the atomizing method, the shape of the raw material may be either powder or bulk, or a combination thereof. These raw materials are melted after being housed in a crucible having a melting point higher than that of calcium fluoride, for example, a crucible made of carbon, Mo, W, Pt or the like. The melting method may be any method as long as the raw material can be heated to the melting point or higher. For example, high frequency, plasma, laser, electron beam, light, or infrared can be used. The raw material is preferably melted in an atmosphere in which the raw material is not evaporated or decomposed and the crucible is not significantly consumed. An optimum atmosphere is selected depending on the heating temperature and the material of the crucible used, such as in the air, in an inert gas, or in a vacuum.

Since the spherical calcium fluoride obtained in the present invention has a high average circularity, it has very good fluidity, exhibits extremely good moldability when filled into a resin, and can increase the filling rate. The obtained spherical particles are classified so as to obtain a desired filling rate, and then subjected to a surface treatment as necessary to further increase the filling rate. As the surface treatment agent, a silane coupling agent is generally used, but a titanate coupling agent and an aluminate coupling agent can also be used.

Next, the resin composition of the present invention will be described.

Examples of the resin used in the present invention include epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide, and other polyamides, polybutylene terephthalate, polyethylene terephthalate. Polyester, polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyether sulfone, polycarbonate, maleimide modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber / styrene) resin, AES (acrylonitrile / ethylene / propylene / diene rubber) -Styrene) resin and the like.

Furthermore, the resin composition of the present invention can contain a stress reducing agent, a silane coupling agent, a surface treatment agent, a flame retardant, a flame retardant aid, a colorant, a release agent, and the like as necessary. . As a stress reducing agent, silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, rubbery substances such as styrene block copolymers and saturated elastomers, various thermoplastic resins, silicone resins, and even epoxy resins, Examples thereof include resins obtained by modifying part or all of the phenol resin with amino silicone, epoxy silicone, alkoxy silicone, and the like. Examples of the silane coupling agent include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, aminopropyltriethoxysilane, ureidopropyltriethoxysilane, N- Examples include aminosilanes such as phenylaminopropyltrimethoxysilane, hydrophobic silane compounds such as phenyltrimethoxysilane, methyltrimethoxysilane, and octadecyltrimethoxysilane, and mercaptosilane. Examples of the surface treatment agent include Zr chelate, titanate coupling agent, aluminum-based coupling agent and the like. Examples of flame retardants include halogenated epoxy resins and phosphorus compounds. Examples of the flame retardant aid include Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O _{5 and the} like. Examples of the colorant include carbon black, iron oxide, dye, and pigment. Examples of the mold release agent include natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters, and paraffin.

1-50 mass parts is preferable with respect to 100 mass parts of spherical calcium fluoride, and, as for the usage-amount of resin in the resin composition of this invention, 10-30 mass parts is more preferable.

The resin composition of the present invention can be produced by mixing the above various materials with a blender or mixer, then melt-kneading with a heating roll, kneader, single or twin screw extruder, Banbury mixer, etc., and cooling.

EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to an Example.

Example 1-4, Comparative Example 1-4
The calcium fluoride raw material powder having the average particle size shown in Table 1 is charged into the high-temperature flame formed by the amount of LPG shown in Table 1 and the amount of oxygen gas shown in Table 1 at the powder supply amount shown in Table 1. Spherical calcium fluoride having the average particle diameter and the average circularity shown in Table 3 was prepared. The purity of the used calcium fluoride raw material powder is 99.5%.

100 parts by weight of spherical calcium fluoride obtained by the above method, 25 parts by weight of a bisphenol A type liquid epoxy resin (“JER828” manufactured by Mitsubishi Chemical Corporation), a planetary stirrer (“Shinky Corporation“ Awatori Kentaro AR-250 ”) Kneaded at a rotational speed of 2000 rpm) to prepare a resin composition.

The characteristics of the particle compositions and resin compositions produced in the examples and comparative examples were evaluated by the following methods. The results are shown in FIG.

[Average particle size]
The measurement was performed using “Laser diffraction particle size distribution measuring device LS 13 320” manufactured by Beckman Coulter. As a sample, 10 cc of pure water and 1 g of spherical calcium fluoride were added to a glass beaker, and dispersion treatment was performed for 1 minute with an ultrasonic cleaner. The dispersion of spherical calcium fluoride that had been subjected to the dispersion treatment was added drop by drop to the laser diffraction particle size distribution measuring device with a dropper, and the ultrasonic wave was irradiated again for 90 seconds. Measurement was performed 60 seconds after irradiation. In the laser diffraction particle size distribution analyzer, the particle size distribution is calculated from the data of the light intensity distribution of the diffracted / scattered light by the particles detected by the sensor. The average particle size was determined by multiplying the value of the measured particle size by the relative particle amount (difference%) and dividing by the total relative particle amount (100%). Here,% is volume%.

[Average circularity]
Measurement was performed using a powder image analyzer (PITA-1) manufactured by Seishin Enterprise Co., Ltd. A sample is dispersed in pure water, and this liquid is allowed to flow in a plane extension flow cell, and 200 spherical calcium fluoride particles moving in the cell are recorded as an image with an objective lens. The average circularity was calculated from equation (1). In formula (1), S represents the area of the recorded image in the particle projection map, and L represents the perimeter of the particle projection map. The average value of the 200 particles calculated in this way was used as the average circularity of the spherical calcium fluoride particles.
Average circularity = 4πS / L ² (1)

[viscosity]
The viscosity of the obtained resin composition was measured under the following conditions using a rheometer (“MCR-300” manufactured by Nippon Shibel Hegner).
Plate shape: Circular flat plate 25mmφ
Sample thickness: 1 mm
Temperature: 25 ± 1 ° C
Shear rate: 0.1 s ^-1

Example 5-8, Comparative Example 5-6
Calcium fluoride raw material powder having an average particle size shown in Table 1 is put into a vertical tubular furnace set at 1600 ° C. in a powder supply amount in Table 1 and subjected to spheronization treatment, and the average particle size shown in Table 3 And spherical calcium fluoride having an average circularity. LPG and oxygen gas were not used. Otherwise, the same procedure as in Example 1 was performed. The results are shown in Table 4.

Example 9-13, Comparative Example 7-9
While the calcium fluoride raw material powder having the average particle size shown in Table 2 is melted at a melting temperature shown in Table 2 in a carbon crucible and dropped through a nozzle having a diameter shown in Table 2, the injection pressure shown in Table 2 By spraying the argon gas, the molten metal was dispersed and sprayed to perform spheroidizing treatment, and spherical calcium fluoride having the average particle diameter and the average circularity shown in Table 3 was produced. Otherwise, the same procedure as in Example 1 was performed. The results are shown in Table 4.

Examples 16-17, Comparative Example 10-12
While the calcium fluoride raw material powder shown in Table 3 was melted at a melting temperature shown in Table 3 in a carbon crucible and dropped through a nozzle having a diameter shown in Table 3, the disk diameter and rotational speed shown in Table 3 were used. Spherical calcium fluoride having the average particle diameter and the average circularity shown in Table 3 was produced by dispersing and spraying the molten metal to perform spheroidization treatment. Otherwise, the same procedure as in Example 1 was performed.
The results are shown in Table 4.

Comparative Example 8
The same operation as in Example 1 was performed except that the calcium fluoride raw material powder itself that was not spheroidized and used in Example 1 was used. The results are shown in Table 4.

The resin composition containing the spherical calcium fluoride of the present invention has a result that the viscosity is kept low and high filling can be achieved as compared with the resin composition containing a calcium fluoride filler having a small average circularity. A scanning electron micrograph showing the shape of the spherical calcium fluoride obtained in Example 1 is shown in FIG. A scanning electron micrograph showing the shape of the calcium fluoride raw material powder of Example 1 (that is, calcium fluoride used in Comparative Example 8) is shown in FIG.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. .

Since the resin composition using the spherical calcium fluoride of the present invention has a low viscosity and can be filled with a high amount, it can be used as a filler for controlling the refractive index, thermal conductivity, thermal expansion coefficient and the like of plastics and rubbers.

Claims (1)

Average particle diameter produced by atomizing method in which calcium fluoride is dissolved and molten metal is dropped onto a rotating disk, and the molten metal is dispersed, sprayed, rapidly solidified, and spheroidized by spheronization. Is 1-50 micrometers, and the manufacturing method of spherical calcium fluoride whose average circularity is 0.90 or more.