JP2008247723A - Method for manufacturing metallic silicon powder, method for manufacturing spherical silica powder, and method for preparing resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which high-purity metallic silicon powder can easily be manufactured. <P>SOLUTION: The method for manufacturing metallic silicon powder is used when spherical silica powder is manufactured by reacting metallic silicon powder with oxygen in a flame, and is characterized by carrying out a purification process twice or more. The purification process comprises: a melting and solidification step of obtaining a solidified product by melting and solidifying crude metallic silicon; a crushing step of obtaining a crushed product by crushing the solidified product; and a removal and washing step of obtaining a treated product by immersing the crushed product in an inorganic acid containing at least hydrofluoric acid for a predetermined time and washing it. Since the solidified product in which impurities contained in the crude metallic silicon are concentrated in an outer side thereof such as a skin part by carrying out melting and solidification is reduced to powder in the crushing step, a powder in which the impurities concentrate in an outer side thereof is obtained. By treating the crushed product with hydrofluoric acid, a part containing high levels of impurities is dissolved and removed and high-purity metallic silicon powder can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing metal silicon powder capable of producing high-purity metal silicon powder by a relatively simple operation, and production of spherical silica powder produced using the metal silicon powder produced by the production method. The present invention relates to a method and a method for producing a resin composition produced using spherical silica powder produced by the production method.

  A semiconductor package is generally sealed with a resin composition containing a spherical silica powder for the purpose of improving thermal properties (Patent Document 1), but the spherical silica powder contains a predetermined amount or more of uranium. If so, the α-rays emitted from the uranium may cause malfunction in the semiconductor to be sealed. Therefore, uranium contained is removed as much as possible. Particularly when the spherical silica powder is produced without controlling the concentration of uranium element (uranium concentration), the uranium concentration is around 30 ppb.

  As a method for producing high-purity metal silicon, not limited to uranium concentration, there is a method for producing high-purity silicon used for semiconductors purified from metal silicon by the monosilane method or silane trichloride method. Is an excessive quality, and a cheaper manufacturing method is desired.

Conventionally, as a method for producing metallic silicon having a purity that can be used for solar cells, (a) Crude silicon is melt-mixed with calcium silicate at a temperature of 1544 ° C. or more, and boron in silicon is transferred into slag. (B) The mixture obtained in step (a) is allowed to stand in an inert gas atmosphere and separated into a lower slag layer and an upper molten silicon layer, and the temperature is set to 1410 to 1544 ° C. While solidifying the slag and holding the silicon in a molten state, (c) the cooling body is immersed in the molten silicon obtained in the step (b) in an inert gas atmosphere to be highly purified on the outer surface of the cooling body. After crystallizing and adhering silicon, the cooling body 2 is pulled up from the molten silicon, the crystallized high-purity silicon mass is removed from the cooling body, and (d) the high-purity silicon obtained in step (c) is again removed. After melting, vacuum processing of the molten silicon is performed in high purity silicon A method of evaporating and removing phosphorus in the glass is disclosed (Patent Document 2).
JP 2000-63630 A JP 7-206420 A

  However, the method for producing high-purity silicon disclosed in Patent Document 2 requires complicated operations, and there is a need for a method for producing metal silicon powder with high purity more easily. Is a method for producing a lump of metallic silicon, and it is necessary to take measures against mixing impurities in the unit operation for pulverization.

  This invention is made | formed in view of the said situation, and makes it the problem which should be solved to provide the manufacturing method which can manufacture a highly pure metal silicon powder easily. Another object to be solved is to provide a production method for producing high-purity spherical silica powder from metal silicon powder produced by the production method. Furthermore, providing the manufacturing method which manufactures a resin composition from the spherical silica powder manufactured with the manufacturing method is also made into the subject which should be solved.

Means for Solving the Problems and Effects of the Invention

(1) The metal silicon powder produced by the method for producing metal silicon powder of the present invention is a method for producing metal silicon powder used when producing spherical silica powder by reacting with oxygen in a flame.

The present inventors have intensively studied for the purpose of solving the above problems, and have completed the following invention. That is, the method for producing a metal silicon powder of the present invention includes a melt solidification step in which a metal silicon raw material is melted and then solidified to obtain a solidified product,
A pulverization step of pulverizing the solidified product to obtain a pulverized product;
After the immersion treatment of the pulverized product in an inorganic acid containing at least hydrofluoric acid for a predetermined time, a cleaning process for obtaining an object to be processed by washing,
The metal silicon powder is obtained by refining a metal silicon raw material having an initial purity of 90% or more by repeating the purification step having 2 or more times.

  After obtaining a solidified product that is formed by segregating and concentrating impurities contained in the raw material at the grain boundaries by melting and solidifying, it is pulverized in the pulverization process to obtain a crystal grain boundary containing a large amount of impurities. Is obtained. In the pulverization step, pulverization proceeds preferentially from the grain boundaries where the impurities segregate, and a portion with a large amount of impurities is exposed on the surface. Impurities include those contained in the raw material and those mixed in the pulverization step.

  By treating the obtained pulverized product with an inorganic acid containing hydrofluoric acid, it is possible to dissolve and remove the surface portion containing a large amount of impurities to obtain a high-purity metal silicon powder. By performing this purification step at least twice, it becomes possible to obtain a metal silicon powder having sufficient purity.

  In the metal silicon powder produced for the purpose of producing a spherical silica powder applied to a semiconductor, the uranium content concentration becomes a particular problem. For the purpose of reducing the concentration of uranium contained in the produced metal silicon powder, the melt solidification step is a segregation step in which the melt is retained near the melting point of silicon to solidify and segregate relatively high-purity metal silicon. The removal cleaning step is a step of dissolving and removing the surface portion of the pulverized product having a relatively high uranium-containing concentration, and the uranium concentration in the produced metal silicon powder is 0.5 ppb or less on a mass basis. It is desirable to be.

(2) The method for producing the spherical silica powder of the present invention that solves the above-described problems is to introduce the metal silicon powder produced by the production method described in (1) above into an oxygen-excess oxygen flame together with a carrier gas. Thus, spherical silica powder is obtained.

  The above-described production method can produce a high-purity metal silicon powder by a simple method, and a high-purity spherical silica powder can be produced by using the obtained metal silicon powder.

(3) The resin composition of the present invention that solves the above problems is obtained by mixing the spherical silica powder produced by the production method described in (2) above and an organic resin material, and using the spherical silica powder as the organic It has the process to disperse | distribute in a resin material, It is characterized by the above-mentioned.

  The above-described production method can produce a high-purity spherical silica powder by a simple method, and a high-purity resin composition can be produced by using the obtained spherical silica powder.

(1) The production method of the present invention will be described in detail below based on the embodiment. The method for producing a metal silicon powder according to the present embodiment is a method for producing a metal silicon powder used in a method for producing a spherical silica powder by reacting a metal silicon powder with oxygen in a flame (so-called VMC method).

  Specifically, a high-purity metal silicon powder can be produced by repeating a predetermined purification step at least twice. The purification process can be repeated until the required purity of the metal silicon powder is reached. As the metal silicon raw material used in the method for producing the metal silicon powder of the present embodiment, a material having a purity of 90% or more is adopted, but it is desirable to employ a material having a purity higher than that.

  As the content of impurities contained in the finally produced metal silicon powder, it is sufficient to appropriately set as necessary, but when used as a raw material for a semiconductor sealing material, It is desirable that the uranium concentration in the water is 0.5 ppb or less by mass.

  The purification process includes a melt solidification process, a pulverization process, a removal cleaning process, and other necessary processes.

  The melt solidification step includes a step of melting the metal silicon raw material and a step of solidifying. The melting step is a step of heating the metal silicon melting point (1412 ° C.) or higher to completely melt the metal silicon raw material. The melting step is desirably performed in an inert atmosphere.

  Here, the heating temperature is desirably slightly higher than the melting point of metallic silicon. By doing so, metallic silicon can be kept in a molten state, and impurities having a high melting point among impurities can be kept in a solidified state. As a result, it is possible to agglomerate impurities on the surface or bottom surface due to the difference in specific gravity between them. In order to complete the aggregation of impurities, it is desirable that the heating time in the melting process is long. Impurities agglomerated on the surface or bottom surface can be easily removed by a pulverization / washing process described later.

  Although it does not specifically limit as a furnace or a crucible used for a fusion | melting process, The thing formed with the high melting-point material with few content of the impurity which becomes a problem is desirable. For example, a crucible or furnace made of alumina, magnesia, zirconia, graphite, or quartz. The heating method is not particularly limited, but a method in which impurities are not mixed, such as heating by electricity, is desirable.

  The solidification step is a step of cooling and solidifying the molten metal silicon raw material. With cooling, first, high-purity metallic silicon is solidified as crystals, and then the remainder containing impurities is solidified so as to surround it. Here, the time required for cooling is not particularly limited, but by cooling for a long time, it is possible to solidify larger crystals of higher-purity metal silicon that does not contain impurities such as uranium from the molten metal silicon raw material. It becomes possible. The solidification step can be performed in the same container (such as a crucible or a furnace) as the melting step, or can be transferred to another container and solidified.

  The pulverization step is a step of pulverizing the obtained solidified product. There is no particular limitation on how the pulverized product is pulverized, but in the final pulverization step, the particle size distribution of the pulverized product is the particle size distribution required for the metal silicon powder that is the final target product. It is desirable to do so.

  In the pulverizing step, a necessary particle size distribution is realized by combining a hammer mill, a ball mill, a vibration mill, a jet mill, or the like. In the pulverization step, classification operation may be performed as necessary.

  The removal cleaning step has a removal step of immersing in an inorganic acid for a predetermined time and a cleaning step of cleaning. In this process, an inorganic acid containing hydrofluoric acid is employed, and impurities are removed by dissolving and removing the surface of the pulverized product obtained in the pulverization step. As the inorganic acid, nitric acid, hydrochloric acid, sulfuric acid and the like can be contained in addition to hydrofluoric acid.

  Impurities are collected on the surface of the solidified product in the above-described melt-solidification process, and the impurities are mixed into the surface of the pulverized product from the pulverizing device in the pulverization process. It is considered that the impurities concentrated on the surface can be effectively removed by the removal.

  The cleaning process is a process of cleaning and cleaning impurities adhering to the surface of the pulverized product in the removing process. Since the surface of the pulverized material is dissolved and removed in the removing step, impurities dissolved by the inorganic acid in addition to the inorganic acid remain as deposits on the surface of the pulverized material. In the cleaning process, the deposits remaining on the surface are cleaned and removed. As a cleaning method, it is desirable to perform cleaning with a cleaning solution that does not contain impurities (especially radioactive elements such as uranium and ionic substances). As the cleaning liquid, pure water is desirable. In addition to pure water, the adhering substance can be removed by selecting an appropriate solvent (for example, an aqueous solvent such as alcohol).

  In addition, the purification step can have a drying step. A drying process is a process of removing the washing | cleaning liquid adhering at the washing | cleaning process by heating after a removal washing | cleaning process or making it pressure reduction state.

(2) The manufacturing method of the spherical silica powder of this embodiment is a method of manufacturing the spherical silica powder by the so-called VMC method using the metal silicon powder manufactured by the manufacturing method described in (1). In the VMC (Vaperized Metal Combustion) method, a chemical flame is formed by a burner in an atmosphere containing oxygen, and metal silicon powder is introduced into the chemical flame in such an amount that a dust cloud is formed, causing deflagration and oxidation. This is a method for obtaining physical particles. Specifically, it is a method of obtaining spherical silica powder by putting the metal silicon powder produced by the production method (1) into an oxygen-excess oxide flame together with a carrier gas.

The operation of the VMC method will be described as follows. First, the container is filled with a gas containing oxygen as a reaction gas, and a chemical flame is formed in the reaction gas. Next, metal powder is introduced into the chemical flame to form a dust cloud with a high concentration (500 g / m ³ or more). Then, thermal energy is given to the metal powder surface by the chemical flame, the surface temperature of the metal powder rises, and metal vapor spreads from the metal powder surface to the surroundings. This metal vapor reacts with oxygen gas to ignite and produce a flame. The heat generated by the flame further promotes the vaporization of the metal powder, and the generated metal vapor and the reaction gas are mixed and propagated in a chain. At this time, the metal powder itself is destroyed and scattered, which promotes flame propagation. The product gas is naturally cooled after combustion, thereby forming a cloud of oxide particles. The obtained oxide particles are collected by a bag filter, an electric dust collector or the like.

  The VMC method uses the principle of dust explosion. According to the VMC method, a large amount of oxide particles can be obtained instantaneously. The resulting oxide particles have a substantially spherical shape. It is possible to adjust the particle diameter of the resulting spherical silica powder by adjusting the particle diameter of the metal silicon powder to be input, the input amount, the flame temperature, and the like. In addition to the metal silicon powder, silica powder can be added as a raw material. The silica powder can maintain the purity of the spherical silica powder obtained by adopting the spherical silica powder obtained by this method.

  When the obtained spherical silica powder is mixed with the resin composition, it can be subjected to a surface treatment for the purpose of improving the adhesion with the resin. For example, various silane, titanate, aluminate and zirconate coupling agents, cations, anions, amphoteric and neutral surfactants can be mixed.

(3) The resin composition of this embodiment has a step of mixing the spherical silica powder and the organic resin material described in (2) and dispersing the spherical silica powder in the organic resin material. The resin composition can be used as a semiconductor liquid sealing material for sealing semiconductor elements, and can also be used for substrate materials, inorganic pastes, adhesives, coating agents, precision molding resins, and the like.

  Since the spherical silica powder is as described above, further explanation is omitted. The spherical silica powder is preferably contained in an amount of 40% by mass or more, more preferably 50% by mass or more based on the total mass.

  Examples of organic resin materials include epoxy resins, oxirane resins, oxetane compounds, cyclic ether compounds, cyclic lactone compounds, thiirane compounds, cyclic acetal compounds, cyclic thioether compounds, spiro orthoester compounds, vinyl compounds, and the like. It can be used alone or in combination.

  In particular, an epoxy resin is preferable from the viewpoints of availability, handleability, and the like. Although an epoxy resin is not specifically limited, The monomer, oligomer, and polymer which have two or more epoxy groups in 1 molecule are mentioned. For example, biphenyl type epoxy resin, stilbene type epoxy resin, bisphenol type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, naphthol type epoxy resin, triazine core containing An epoxy resin is mentioned.

  Specific examples other than the epoxy resin include oxirane compounds such as phenyl glycidyl ether, ethylene oxide and epichlorohydrin; oxetane compounds such as trimethylene oxide, 3,3-dimethyloxetane and 3,3-dichloromethyloxetane; tetrahydrofuran, 2 Cyclic ether compounds such as 1,3-dimethyltetrahydrofuran, trioxane, 1,3-dioxofuran, 1,3,6-trioxacyclooctane; cyclic lactone compounds such as β-propiolactone and ε-caprolactone; ethylene sulfide, 3, Thiane compounds such as 3-dimethylthiirane; Thiane compounds such as 1,3-propyne sulfide and 3,3-dimethyl thietane; Cyclic thioether compounds such as tetrahydrothiophene derivatives; Spiro ortho ester compounds obtained by reaction with kuton; spiro ortho carbonate compounds; cyclic carbonate compounds; vinyl compounds such as ethylene glycol divinyl ether, alkyl vinyl ether, triethylene glycol divinyl ether; styrene, vinyl cyclohexene, isobutylene, polybutadiene, etc. An ethylenically unsaturated compound can be illustrated. As a cationically polymerizable compound, an epoxy resin and these compounds can be used alone or in combination.

  As a curing agent to be added when an epoxy resin is employed, a primary amine, a secondary amine, a phenol resin, or an acid anhydride may be used. As a curing catalyst, Bronsted acid, Lewis acid, basic catalyst, or the like may be used. Used. As the basic catalyst, imidazole, dicyandiamide, amine adduct, phosphine, and hydrazide are used.

  Metallic silicon was melted at 1480 ° C. for 10 hours (melting step), and then cooled and solidified (solidification step and melt solidification step). The obtained metal silicon solidified product was pulverized until the volume average particle size became 2 mm or less to obtain a pulverized product (pulverization step).

  The obtained pulverized product was immersed in a 2 mass% hydrofluoric acid aqueous solution and stirred for 15 hours (removal step). Then, after the pulverized product was separated by filtration, it was washed with pure water (cleaning process and removal cleaning process). Then, it dried (drying process).

  This purification process consisting of the melt solidification process, the removal washing process and the drying process was repeated once more to obtain the metal silicon powder of this example.

  The purification process in Example 1 was performed three times, and the obtained metal silicon powder was used as the metal silicon powder of this example.

Comparative example

  The purification process in Example 1 was performed once, and the obtained metal silicon powder was used as the metal silicon powder of this comparative example.

(Evaluation)
Table 1 shows the analysis results of the obtained metal silicon powders of Examples and Comparative Examples.

  As is clear from the table, the uranium content in the metal silicon raw material was 33 ppb, whereas the metal silicon powder obtained by any of the production methods of Examples and Comparative Examples contained uranium. The amount decreased. However, the metal silicon powder of the comparative example in which the purification process has been performed only once retains uranium 7 times or more as compared with the metal silicon powder produced by the production method of the example in which the purification process has been performed twice or more. It became clear.

(Production of spherical silica powder)
Spherical silica powder was produced by the VMC method using the metal silicon powders of Example 1 and Comparative Example.

  The spherical silica powder and resin composition of the present invention will be described in more detail based on examples. The raw material powder was put into the spherical silica particle explosion combustion apparatus of each example and comparative example.

Specifically, oxygen as a carrier gas and propane gas as a combustible gas were respectively introduced into a reaction vessel, and then ignited with a burner to form a flame, thereby sufficiently drying the inside of the reaction vessel. Carrier gas was introduced into the reaction vessel at a flow rate of 20 Nm ³ / hour and combustible gas at a flow rate of 1.0 Nm ³ / hour.

  Next, the metal silicon powder was oxidized by introducing it into the reaction vessel through a burner at a supply rate of 10 kg / hour with a carrier gas and ejecting it into the flame. The raw material metal silicon powder formed spherical silica powder by oxidation. The uranium content of the obtained spherical silica powder was measured. The results are shown in Table 2.

  As is clear from Table 2, the spherical silica powder of Example 1 having a lower uranium content in the metal silicon powder as the raw material had a lower uranium content.

  As is clear from the above results, according to the production method of the example employing the purification process of the present invention twice or more, it is possible to easily produce high-purity metal silicon powder and spherical silica powder. I understood.

Claims (4)

A method of producing the metal silicon powder for use in producing spherical silica powder by reacting metal silicon powder with oxygen in a flame,
After melting the metal silicon raw material, it is solidified to obtain a solidified product by solidification;
A pulverization step of pulverizing the solidified product to obtain a pulverized product;
After the immersion treatment of the pulverized product in an inorganic acid containing at least hydrofluoric acid for a predetermined time, a cleaning process for obtaining an object to be processed by washing,
A method for producing a metal silicon powder, wherein the metal silicon powder is obtained by refining a metal silicon raw material having an initial purity of 90% or more by repeating the purification step having 2 or more times. The melt solidification step has a segregation step in which the melt is held near the melting point of silicon to solidify and segregate relatively high-purity metallic silicon,
The removal cleaning step is a step of dissolving and removing the surface portion of the pulverized product having a relatively high uranium-containing concentration,
The method for producing a metal silicon powder according to claim 1, wherein the uranium concentration in the produced metal silicon powder is 0.5 ppb or less on a mass basis.   A method for producing a spherical silica powder, characterized in that a metallic silica powder produced by the production method according to claim 1 or 2 is put together with a carrier gas into an oxygen-excess oxygen flame to obtain a spherical silica powder.   A resin composition comprising a step of mixing the spherical silica powder produced by the production method according to claim 3 and an organic resin material, and dispersing the spherical silica powder in the organic resin material. Production method.