JP2004296733A - Method for separating solid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel method for cleaning an inorganic solid by which impurities can be economically and efficiently separated from an inorganic solid in a mixture that contains the inorganic solid including impurities and a solvent, and a novel method for dispersing inorganic particulates by which inorganic particulates forming a secondary aggregate can be economically, efficiently and easily dispersed as primary particles in a solvent, in a mixture that contains a secondary aggregate formed of inorganic particles and a solvent. <P>SOLUTION: The method for cleaning an inorganic solid is used to separate impurities from an inorganic solid and clean the inorganic solid by allowing a specific compound to exist in a mixture that contains the inorganic solid including impurities and the solvent. The method for dispersing inorganic particulates is used to disperse inorganic particulates as primary particles in the solvent by allowing a specific compound to exist in a mixture that contains a secondary aggregate formed of inorganic particles and the solvent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention (first and second inventions) relates to a method for separating adhered, fixed or aggregated solids. The details are as follows.
The first invention relates to a method for purifying an inorganic solid by separating impurities from the inorganic solid in a mixture containing the inorganic solid containing the impurity and a solvent.
The second invention relates to a method for separating and monodispersing inorganic fine particles as primary particles in a mixture containing a secondary aggregate of inorganic fine particles and a solvent.
[0002]
[Prior art]
<Prior art related to the first invention>
Conventionally, impurities such as a compound metal and a different metal contained in a Si-based semiconductor, and a compound of a different metal affect semiconductor characteristics such as electric characteristics and optical characteristics of these semiconductors. It is important to use a strictly purified (purified) compound semiconductor as a raw material in order to obtain excellent characteristics as an optoelectronic device using a semiconductor. In particular, in the case of luminescent materials such as zinc sulfide (ZnS) and CdSe, even if impurities are contained in the order of ppm, the effects of the impurities appear remarkably on the emission characteristics, so that advanced cleaning technology is required. I was
[0003]
However, in the conventionally known methods for cleaning inorganic solids such as metals, it is very difficult to reduce the content of metals and metal-containing compounds (compound semiconductors, metal oxides, etc.) as impurities to the order of ppm or less. It was difficult. In particular, it has been extremely difficult to separate and remove copper and copper-containing compounds.
Metals and metal-containing compounds as impurities are very slightly mixed in a segregated state.However, methods for selectively removing such a small amount of segregated matter so that the content is on the order of ppm or less have been known. There is no report indicating this.
[0004]
<Prior art related to the second invention>
Conventionally, as a method of dispersing (monodispersing) inorganic particles in a solvent, that is, a method of preparing a dispersion of inorganic particles, a mechanical dispersing method using various dispersing devices and a stirring device, and various dispersing agents Various methods are known, such as a chemical dispersion method using the same.
However, in any method, it has been difficult to efficiently and easily separate inorganic particles secondary aggregated in a solvent as primary particles and disperse them in the solvent. Furthermore, when the above-mentioned inorganic particles become micro-sized or nano-sized fine particles or ultrafine particles, it has been extremely difficult to disperse the secondary aggregates and then disperse them as primary particles.
[0005]
[Problems to be solved by the invention]
<Problem of the first invention>
The problem to be solved by the first invention is to provide a novel method capable of economically, efficiently and easily separating impurities from an inorganic solid in a mixture containing the solvent and an inorganic solid containing the impurities. Is to do.
<Subject of the second invention>
The problem to be solved by the second invention is that, in a mixture containing a secondary aggregate of inorganic fine particles and a solvent, the secondary aggregate is economically, efficiently, and easily separated as primary particles to form a mixture in a solvent. To provide a new method that can be dispersed in
[0006]
[Means for Solving the Problems]
<Means for Solving the Problem of the First Invention>
The present inventor has conducted intensive studies in order to solve the above problems. In the process, as a result of repeating experiments and examinations by trial and error, a mixture containing the above-described inorganic solid containing impurities and a solvent was added to a specific compound, namely, a carboxylic acid, a halide ion, and It was confirmed that if at least one member selected from the group consisting of halide ion-forming compounds was added to make it exist, the above problems could be solved at once and easily, and the present invention was completed. Reached.
[0007]
That is, the method for purifying an inorganic solid according to the first invention includes:
In a mixture containing an inorganic solid containing impurities and a solvent, a carboxylic acid, a halide ion, and at least one selected from the group consisting of compounds that generate a halide ion in the mixture are present, whereby the inorganic solid is formed. And cleaning the inorganic solid by separating the impurities from the inorganic solid.
<Means for Solving the Problem of the Second Invention>
The present inventor has conducted intensive studies in order to solve the above problems. In the process, as a result of repeating experiments and studies by trial and error, a specific compound, that is, a carboxylic acid, a halide ion, and a mixture containing a secondary aggregate of inorganic fine particles and a solvent described above were added to the mixture containing the solvent and the solvent. It has been confirmed that if at least one member selected from the group consisting of halide ion-generating compounds is added to the mixture to make it exist, the above-mentioned problems can be solved at once and easily, and the present invention has been completed. I came to.
[0008]
That is, the method for dispersing inorganic fine particles according to the second invention is as follows.
In a mixture containing a secondary aggregate of inorganic fine particles and a solvent, a carboxylic acid, a halide ion, and the presence of at least one selected from the group consisting of compounds that generate a halide ion in the mixture are present. The method is characterized in that inorganic fine particles are dispersed as the primary particles in the solvent.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
<Inorganic solid cleaning method according to the first invention>
Hereinafter, the method for cleaning an inorganic solid according to the present invention will be described in detail, but the scope of the present invention is not limited to these descriptions, and other than the following examples, as long as the purpose of the present invention is not impaired. Changes can be made as appropriate.
The method for cleaning inorganic solids of the present invention (hereinafter, may be referred to as the first method) includes the steps of: mixing a mixture containing an inorganic solid containing impurities and a solvent with a carboxylic acid, a halide ion, and In the presence of at least one selected from the group consisting of compounds that generate halide ions, the impurities are separated from the inorganic solid to clean the inorganic solid.
[0010]
Hereinafter, a mixture containing an inorganic solid containing impurities and a solvent, which may be an object in the first method, will be described, and the impurities will be separated from the inorganic solid by using a specific compound to purify the inorganic solid. The method and the conditions thereof will be described in detail.
The mixture referred to in the first method is a mixture containing an inorganic solid containing impurities and a solvent. The form of the mixture is not particularly limited, and examples thereof include a slurry state and a state in which a solid precipitates in a solvent.
The ratio of the inorganic solid containing impurities in the mixture is not particularly limited, but may be, for example, 1 to 80% by weight.
[0011]
Examples of the solvent include water and various non-aqueous solvents (e.g., conventionally known organic solvents such as hydrocarbons, aldehydes, ketones, esters, amides, and alcohols, silicone oil, and mineral oil). be able to.
In the first method, the inorganic solid, that is, the solid made of an inorganic substance is not particularly limited, but examples thereof include a compound semiconductor, a metal, and a metal oxide. Among them, compound semiconductors are examples of the inorganic solid in which the effect of the cleaning by the first method is more exhibited.
The form of the inorganic solid is not particularly limited. For example, it may be in the form of fine particles, coarse particles, or a compact. Here, the fine particles mean particles having a particle diameter of less than 1 μm, and the coarse particles mean particles having a particle diameter of 1 μm or more.
[0012]
Although the shape of the inorganic solid is not particularly limited, for example, a sphere (true sphere), an ellipsoidal sphere, a cube, a rectangular parallelepiped, a polyhedron, a pyramid, a needle, a column, a rod, a tube, a scale, Examples thereof include a flaky shape such as a (hexagonal) plate shape, a dendritic shape, and a skeletal shape. The crystallinity of the inorganic solid is not particularly limited, and may be, for example, any of a single crystal, a polycrystal, and an amorphous. Also, the production method for obtaining these is not particularly limited, and it may be obtained as a sintered body obtained through a crystallization process or as a non-sintered body.
Above all, when the inorganic solid is a polycrystal and / or a sintered body, impurities are often present in the form of fine particles or films at the grain boundaries as segregates, and the impurities are easily removed. The first method according to the present invention can be preferably applied. When the inorganic solid is a polycrystalline body and / or a sintered body, the inorganic solid may be used in the form of fine particles in advance, or a specific compound described below may be used to separate impurities and remove the inorganic solid. Fine particles are preferred in that the cleaning effect of the first method can be enhanced. The method for previously converting the inorganic solid into fine particles is not particularly limited, and examples thereof include mechanical methods such as crushing and pulverization.
[0013]
When the inorganic solid is a compound semiconductor, the compound semiconductor is not particularly limited, but specifically, for example, C, Si, Ge, Sn, Pb, N, P, As, Sb, S, Se At least one element X selected from the group consisting of Ti and Te, and at least one metal element M that is not the same as the element X are formed as an essential combination of elements (elements constituting a compound). A compound semiconductor (hereinafter, sometimes referred to as a compound semiconductor MX) is preferably exemplified.
Examples of the metal element M include groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8, 8, 1B, 2B, 3B, and 4B other than C and N in the periodic table. At least one member selected from the group consisting of group 5B, group 6B other than O and S, lanthanoid elements, and actinoid elements can be used. In this specification, the periodic table uses the “Periodic Table of Elements (1993)” published in the revised 5th edition “Chemical Handbook (edited by The Chemical Society of Japan)” (published by Maruzen Co., Ltd.). The tribal number is indicated by the subtribal system.
[0014]
The compound semiconductor MX may be a compound composed of the above-described element X and the metal element M. For example, a compound in which a part of the metal element M is substituted with H (hydrogen atom) (in a mixed crystal described later) , The second, the third, the fourth,..., And the metal element M using H) and the element X in which a part of the element X is replaced by O (oxygen atom). Yes, there is no particular limitation. The element to be doped in the solid solution described below is not particularly limited, and any element can be selected and used.
The compound semiconductor MX is not necessarily limited to a compound having functions and physical properties peculiar to a semiconductor. If the compound semiconductor MX is a combination of the above elements X and M, a compound having a very low semiconductor property or a semiconductor property may be used. It is assumed that a compound having no compound may be contained.
[0015]
As the compound semiconductor MX, for example, so-called III-V compounds, II-VI compounds, IV-IV compounds, and IV-VI compounds are preferably exemplified. As the compound semiconductor having light-emitting properties, a direct transition III- V compounds and II-VI compounds are preferably exemplified.
The III-V compound is a compound of a combination of a 3B group element of the periodic table as the metal element M and a 5B group element as the element X. Specifically, for example, GaAs, GaAsP, GaAlAs, AlP, InP , GaP, InGaAlP, AlS, GaN, InGaN, BN, InSb, GaSb, and nitrides of BAlGaIn. Among them, GaN, InGaN, GaAs, GaAsP, and the like are excellent in light emission characteristics. No.
[0016]
The II-VI compound is a compound of a combination of a group 2B element of the periodic table as the metal element M and a group 6B element excluding oxygen as the element X. Specifically, for example, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, and the like can be given. Among them, those having excellent emission characteristics include CdS, CdSe, ZnSe, ZnS, ZnMgSe, and the like.
The IV-IV compound is a compound of a combination of elements of the 4B group of the periodic table as the metal element M and the element X, and specifically includes, for example, SiC, SiGe, etc. SiC and the like are excellent examples.
[0017]
The IV-VI compound is a compound of a combination of a Group 4B element of the periodic table as the metal element M and a Group 6B element excluding oxygen as the element X. Specifically, for example, SnTe, PbS, PbSe, PbTe and the like can be mentioned, and among them, PbTe and the like are exemplified as those having excellent light emitting characteristics.
The compound semiconductor MX may be in the form of a mixed crystal. The mixed crystal of the compound semiconductor generally includes a ternary mixed crystal, a quaternary mixed crystal, a ternary mixed crystal, a hexagonal mixed crystal, and the like (the binary compound) such as the above-described III-V compound. However, various chemical and physical properties are uniquely determined and there is no room for artificial control. However, in the case of a mixed crystal form, it can be controlled by the mixing ratio of elements. For example, the lattice constant and the band structure can be set independently.
[0018]
The compound semiconductor MX is not limited to a compound having a stoichiometric composition (for example, Cd: Se = 1: 1 in the case of CdSe), but has a non-stoichiometric composition (for example, CdSe)._0.98Se_1.0And a compound having a stoichiometric composition and a compound having a non-stoichiometric composition may be mixed, and there is no particular limitation. Further, in the present specification, when the MX compound is a compound having a mixed crystal form, for example, Cd_{1- x}Zn_xSe_1-yS_yAnd Cd_1-xZn_xSe₁Is generally referred to simply as CdZnSeS or CdZnSe. Therefore, for example, InGaN does not mean a form in which the element ratio is In: Ga: N = 1: 1: 1, but In is a compound form having a stoichiometric composition._0.1Ga_0.9N_1.0And / or a non-stoichiometric compound form thereof.
[0019]
The compound semiconductor MX may be in the form of a solid solution doped with a different metal element or a non-metal element, such as ZnS doped with Mn. As a different metal or non-metal element to be doped, for example, Sb³⁺, Sn²⁺, Pb²⁺And Tl⁺Typical metal ions such as Mn²⁺, Cr³⁺, Ag⁺And Cu²⁺Transition metal ions such as Eu;²⁺, Eu³⁺, Tb³⁺, Er³⁺, Sm³⁺, Nd³⁺, Ho³⁺And Yb³⁺And halogen atoms such as F and Cl; and the like, and an effect such as exhibiting sharp emission characteristics with a narrow emission wavelength width can be provided.
[0020]
When the inorganic solid is a compound semiconductor, it is preferably in the form of fine particles, and the particle diameter is preferably in a nano-sized region of less than 1 μm, more preferably less than 100 nm, and further preferably less than 10 nm.
When the inorganic solid is a metal, examples of the metal include a Group 8 metal such as Fe, Co, Ni, Pd and Pt, a Group 1B metal such as Cu, Ag and Au, Al, Ga and In. Group 3B metal such as Si, Ge and Sn, group 5B metal such as P and Bi, and group 6B metal such as Se and Te.
[0021]
When the inorganic solid is a metal oxide, examples of the metal oxide include various metal oxides (single oxide, composite oxide, and solid solution oxide) conventionally known in this technical field. it can.
The impurities referred to in the first method, that is, the impurities contained in the inorganic solid include: (1) a simple substance of the element (a) other than the component elements constituting the inorganic solid and a compound containing the element (a); ▼ It means a simple substance or a compound containing at least one kind of component elements constituting the inorganic solid and having an element composition different from that of the inorganic solid.
[0022]
The state of the impurities in the inorganic solid is not particularly limited, and examples thereof include atoms, ions, molecules, fine particles, and films. Above all, the first method can be preferably applied to an inorganic solid contained as fine particles or a film as a segregated substance, and a high cleaning effect can be obtained.
The impurities are not particularly limited, but specifically include, for example, simple Cu, simple Se, single Te, simple S, CuSe, CuS, CuTe, and the like, and these are applied by the first method. Thereby, it can be efficiently separated from the inorganic solid. These impurities can be economically, efficiently and easily separated from the inorganic solid by a separating action of a specific compound described later. In the case where the inorganic solid is a II-VI compound semiconductor such as CdSe or ZnS, examples of the above-mentioned (1) impurities include simple Cu and CuS, and examples of the above-mentioned (2) impurities. , Cd alone (excess component), Zn alone (excess component), S (excess component), Se alone (excess component), CuSe, CuS and ZnO.
[0023]
In the case where the inorganic solid is a polycrystal of the compound semiconductor MX described above, the impurities include M, X and Mp (where Mp is X and At least one kind of metal element that is not the same and a metal element different from M.), and at least one kind selected from the group consisting of compound semiconductors Mp-X. In particular, when the compound semiconductor MX is Cu-X and the impurity is Cu, even if the content of the impurity is extremely small, it can be efficiently and easily separated from the inorganic solid and purified. Thus, the first method can be suitably adopted in that it can be performed.
[0024]
The mixture referred to in the first method may contain other components in addition to the above-mentioned inorganic solid containing impurities and the solvent.
In the first method, a specific compound, that is, a carboxylic acid, a halide ion, and a compound that generates a halide ion in the mixture are added to the mixture containing the inorganic solid containing impurities and the solvent described above. At least one selected member is added so as to be present. As a result, the above-described problem can be solved at once and easily.
In the first method, the method for causing the specific compound to exist in a mixture containing an inorganic solid containing impurities and a solvent is not particularly limited. Further, since it is sufficient that the compound is finally present in the mixture, there is no particular limitation on the timing at which the specific compound is used (addition timing). For example, the specific compound may be added after mixing the inorganic solid containing the impurity and the solvent, or the specific compound may be added to the inorganic solid containing the impurity in advance and mixed with the solvent, The above specific compound may be added to a solvent in advance and mixed with an inorganic solid containing impurities.
[0025]
Although it does not specifically limit as said carboxylic acid, For example, aliphatic saturated monocarboxylic acids, such as formic acid, acetic acid, propionic acid, butyric acid, lauric acid, and stearic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, and adipine Aliphatic saturated dicarboxylic acids such as acid and sebacic acid; aliphatic unsaturated (mono, di, polyvalent) carboxylic acids such as acrylic acid, propiolic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and mesaconic acid; Carbocyclic (mono, di, polyvalent) carboxylic acids such as acids, phthalic acid, terephthalic acid and naphthoic acid, toluic acid, hydroatropic acid and cinnamic acid; furic acid, tenic acid, nicotinic acid and isonicotinic acid, hydroxy Carboxylic acids, heterocyclic carboxylic acids such as alkoxycarboxylic acids; glycolic acid, lactic acid, glyceric acid, malic acid, Stone acid, benzyl acid, salicylic acid, 3,4-dihydroxybenzoic acid, anisic acid, such as piperonyl acid preferred. Above all, an aliphatic saturated monocarboxylic acid having 1 to 4 carbon atoms is more preferable in that it has a high ability to disperse impurities in a solvent. These may be used alone or in combination of two or more.
[0026]
Although it does not specifically limit as said halide ion, For example, a fluoride ion (F⁻), Chloride ions (Cl⁻), Bromide ion (Br)⁻) And iodide ions (I⁻) And the like. These may be used alone or in combination of two or more.
The compound that generates halide ions in the mixture is not particularly limited, but includes hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide, and aqueous solutions thereof, and alkali metals and alkaline earth metals. And the like. These may be used alone or in combination of two or more.
[0027]
In the first method, the proportion (blending ratio) of the specific compound described above in addition to the mixture containing the inorganic solid containing impurities and the solvent is not particularly limited, but, for example, the inorganic solid contained in the mixture may be used. Is preferably 0.0001 to 100 mol% based on the number of metal atoms contained in the compound. When the mixing ratio is less than 0.0001 mol%, the dispersing effect may not be sufficiently exhibited. When the mixing ratio is more than 100 mol%, even if the amount is further increased, the dispersing effect is not significantly improved. , On the contrary, there is a possibility that it will decrease.
In the first method, when the specific compound described above is present in the mixture, the mixture may be stirred or heated. The separation of impurities from the inorganic solid can be further promoted by stirring or heating. The method and conditions for stirring and heating are not particularly limited, and can be appropriately adopted and set. The temperature for heating is not particularly limited, but is preferably, for example, 50 ° C. or more and less than 300 ° C., and more preferably a temperature higher than the boiling point of the solvent.
[0028]
In the first method, when the above-mentioned specific compound is present in the mixture, the inorganic solid containing the impurity may be finely divided. Examples of the method for making finer include dry or wet mechanical methods using various pulverizing methods and grinding methods.
In this manner, by refining the inorganic solid containing impurities, impurities existing inside the inorganic solid, such as impurities existing at the grain boundaries or the like, can be exposed on the surface, so that the impurities can be more easily separated. Effects and the like are obtained. Further, as an incidental effect, a reaction occurs between the impurities due to the energy added during the miniaturization, and the fine impurities are aggregated into particles (fine particles), whereby the adsorption efficiency of the specific compound is increased, and The effect of increasing the efficiency of separating impurities can be obtained.
[0029]
The size of the fine inorganic solid containing impurities is preferably larger than the impurities, specifically, preferably 1 nm to 10 μm, more preferably 50 nm to 1 μm. The shape of the inorganic solid containing impurities obtained after the miniaturization is not particularly limited.
In refining the inorganic solid containing impurities, the timing of the miniaturization and the timing (addition timing) of using the above-mentioned specific compound are not particularly limited. For example, the inorganic solid containing impurities and the solvent may be mixed. The mixture containing the specific compound may be subjected to the treatment for refining the inorganic solid in a state where the specific compound is added, or the mixture containing the inorganic solid containing impurities and the solvent may be subjected to the fine treatment of the inorganic solid. The specific compound may be added after the chemical conversion treatment, or the solvent and the specific compound may be added after the fine solidification treatment is performed on the inorganic solid containing impurities in advance. .
[0030]
In the first method, the above-mentioned specific compound is added to a mixture containing an inorganic solid and a solvent so as to exist, and after separating impurities, an operation of removing the separated impurities is performed. This removal operation is not particularly limited, but can be performed by, for example, a method such as filtration, removal of a supernatant, and centrifugation.
By carrying out the first method, the impurities contained in a trace amount in the inorganic solid can be efficiently separated and removed. Specifically, the ratio of the impurities contained in the inorganic solid before the implementation is 0.1%. The first method can be preferably applied when the content is from 01 ppm to 5 wt%, and more preferably from 0.1 ppm to 1 wt%. In this case, the ratio of impurities contained in the inorganic solid obtained by performing the first method is not particularly limited, but is preferably 0.001 ppm to 0.5 wt%, more preferably It is 0.001 to 10 ppm, more preferably 0.001 to 0.1 ppm.
[0031]
By performing the first method, the inorganic solid can be economically, efficiently, and easily cleaned, and the purity of the inorganic solid can be increased. As a result, for example, an inorganic solid having excellent electrical properties, optical properties, (optical) magnetic properties, and the like, as well as semiconductor properties such as electron conductivity, photoconductivity, magneto-optical properties, and luminescent properties can be obtained.
<Dispersion method of inorganic fine particles according to second invention>
Hereinafter, the method of dispersing inorganic fine particles according to the present invention will be described in detail, but the scope of the present invention is not limited to these descriptions, and other than the following examples, as appropriate, within a range that does not impair the spirit of the present invention. Changes can be made.
[0032]
The method for dispersing inorganic fine particles of the present invention (hereinafter, may be referred to as a second method) is a method in which a mixture containing a secondary aggregate of inorganic fine particles and a solvent is mixed with a carboxylic acid, a halide ion, and a mixture thereof. The inorganic fine particles are dispersed in the solvent as primary particles by the presence of at least one selected from the group consisting of compounds that generate halide ions.
The second method is a dispersion method that can be suitably performed as the inorganic fine particles forming the secondary aggregates are finer. In the second method, in separating and dispersing the inorganic fine particles forming the secondary aggregate, all the fine particles that are secondary aggregated can be easily dispersed as primary particles. The present invention is not limited thereto, and may be a case where a part of the secondary aggregated fine particles are separated and dispersed.
[0033]
Hereinafter, a mixture containing a secondary aggregate of inorganic fine particles and a solvent which can be a target of the second method will be described, and the inorganic fine particles forming the secondary aggregate will be separated by using a specific compound to form the mixture. The method of forming the inorganic fine particles into primary particles and dispersing (monodispersing) them and the conditions thereof will be described in detail.
Since the second method is a method of monodispersing the secondary aggregated inorganic fine particles as described above, the inorganic fine particles are substantially formed from a mixture containing a secondary aggregate of inorganic fine particles and a solvent. This is a method for producing a dispersed “inorganic fine particle dispersion (dispersion liquid)”.
[0034]
The mixture referred to in the second method is a mixture containing secondary aggregated inorganic fine particles and a solvent. The form of the mixture is not particularly limited, and examples thereof include a slurry state and a state in which inorganic fine particles are precipitated in a solvent.
The proportion of the secondary aggregated inorganic fine particles in the mixture is not particularly limited, but may be, for example, 1 to 80% by weight.
Regarding the secondary agglomerated inorganic fine particles, the degree of agglomeration may be 2 to 1000 inorganic fine particles, 1000 to 1,000,000, or 1,000,000 or more inorganic fine particles per secondary aggregate. May be used, and there is no particular limitation.
[0035]
Examples of the solvent include water and various non-aqueous solvents (e.g., conventionally known organic solvents such as hydrocarbons, aldehydes, ketones, esters, amides, and alcohols, silicone oil, and mineral oil). be able to.
In the second method, as the inorganic fine particles, that is, inorganic fine particles, for example, compound semiconductor fine particles, metal fine particles, and metal oxide fine particles are preferably exemplified. Among them, compound semiconductor fine particles are more effective in achieving the monodispersion effect of the second method.
The form of the inorganic fine particles is not particularly limited. For example, it may be in the form of fine particles, coarse particles, or a compact. Here, the fine particles mean particles having a particle diameter of less than 1 μm, and the coarse particles mean particles having a particle diameter of 1 μm or more.
[0036]
Although the shape of the inorganic fine particles is not particularly limited, for example, a spherical shape (true spherical shape), an elliptical spherical shape, a cubic shape, a rectangular parallelepiped shape, a polyhedral shape, a pyramid shape, a needle shape, a columnar shape, a rod shape, a tubular shape, a scale shape, Examples thereof include a flaky shape such as a (hexagonal) plate shape, a dendritic shape, and a skeletal shape.
The crystallinity of the inorganic fine particles is not particularly limited, and may be, for example, any of a single crystal, a polycrystal, and an amorphous. Also, the production method for obtaining these is not particularly limited, and it may be obtained as a sintered body obtained through a crystallization process or as a non-sintered body. Also, the size of the secondary particles is not particularly limited, and may be, for example, 20 nm to 10 mm or more.
[0037]
When the inorganic fine particles are a compound semiconductor, the compound semiconductor is not particularly limited, but specifically, for example, C, Si, Ge, Sn, Pb, N, P, As, Sb, S, Se At least one element X selected from the group consisting of Ti and Te, and at least one metal element M that is not the same as the element X are formed as an essential combination of elements (elements constituting a compound). A compound semiconductor (hereinafter, sometimes referred to as a compound semiconductor MX) is preferably exemplified.
Examples of the metal element M include groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8, 8, 1B, 2B, 3B, and 4B other than C and N in the periodic table. At least one member selected from the group consisting of group 5B, group 6B other than O and S, lanthanoid elements, and actinoid elements can be used. In this specification, the periodic table uses the “Periodic Table of Elements (1993)” published in the revised 5th edition “Chemical Handbook (edited by The Chemical Society of Japan)” (published by Maruzen Co., Ltd.). The tribal number is indicated by the subtribal system.
[0038]
The compound semiconductor MX may be a compound composed of the above-described element X and the metal element M. For example, a compound in which a part of the metal element M is substituted with H (hydrogen atom) (in a mixed crystal described later) , The second, the third, the fourth,..., And the metal element M using H) and the element X in which a part of the element X is replaced by O (oxygen atom). Yes, there is no particular limitation. The element to be doped in the solid solution described below is not particularly limited, and any element can be selected and used.
The compound semiconductor MX is not necessarily limited to a compound having functions and physical properties peculiar to a semiconductor. If the compound semiconductor MX is a combination of the above elements X and M, a compound having a very low semiconductor property or a semiconductor property may be used. It is assumed that a compound having no compound may be contained.
[0039]
As the compound semiconductor MX, for example, so-called III-V compounds, II-VI compounds, IV-IV compounds, and IV-VI compounds are preferably exemplified. As the compound semiconductor having light-emitting properties, a direct transition III- V compounds and II-VI compounds are preferably exemplified.
The III-V compound is a compound of a combination of a 3B group element of the periodic table as the metal element M and a 5B group element as the element X. Specifically, for example, GaAs, GaAsP, GaAlAs, AlP, InP , GaP, InGaAlP, AlS, GaN, InGaN, BN, InSb, GaSb, and nitrides of BAlGaIn. Among them, GaN, InGaN, GaAs, GaAsP, and the like are excellent in light emission characteristics. No.
[0040]
The II-VI compound is a compound of a combination of a group 2B element of the periodic table as the metal element M and a group 6B element excluding oxygen as the element X. Specifically, for example, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, and the like can be given. Among them, those having excellent emission characteristics include CdS, CdSe, ZnSe, ZnS, ZnMgSe, and the like.
The IV-IV compound is a compound of a combination of elements of the 4B group of the periodic table as the metal element M and the element X, and specifically includes, for example, SiC, SiGe, etc. SiC and the like are excellent examples.
[0041]
The IV-VI compound is a compound of a combination of a Group 4B element of the periodic table as the metal element M and a Group 6B element excluding oxygen as the element X. Specifically, for example, SnTe, PbS, PbSe, PbTe and the like can be mentioned, and among them, PbTe and the like are exemplified as those having excellent light emitting characteristics.
The compound semiconductor MX may be in the form of a mixed crystal. The mixed crystal of the compound semiconductor generally includes a ternary mixed crystal, a quaternary mixed crystal, a ternary mixed crystal, a hexagonal mixed crystal, and the like (the binary compound) such as the above-described III-V compound. However, various chemical and physical properties are uniquely determined and there is no room for artificial control. However, in the case of a mixed crystal form, it can be controlled by the mixing ratio of elements. For example, the lattice constant and the band structure can be set independently.
[0042]
The compound semiconductor MX is not limited to a compound having a stoichiometric composition (for example, Cd: Se = 1: 1 in the case of CdSe), but has a non-stoichiometric composition (for example, CdSe)._0.98Se_1.0And a compound having a stoichiometric composition and a compound having a non-stoichiometric composition may be mixed, and there is no particular limitation. Further, in the present specification, when the MX compound is a compound having a mixed crystal form, for example, Cd_1-xZn_xSe_1-yS_yAnd Cd_1-xZn_xSe₁Is generally referred to simply as CdZnSeS or CdZnSe. Therefore, for example, InGaN does not mean a form in which the element ratio is In: Ga: N = 1: 1: 1, but In is a compound form having a stoichiometric composition._0.1Ga_0.9N_1.0And / or a non-stoichiometric compound form thereof.
[0043]
The compound semiconductor MX may be in the form of a solid solution doped with a different metal element or a non-metal element, such as ZnS doped with Mn. As a different metal or non-metal element to be doped, for example, Sb³⁺, Sn²⁺, Pb²⁺And Tl⁺Typical metal ions such as Mn²⁺, Cr³⁺, Ag⁺And Cu²⁺Transition metal ions such as Eu;²⁺, Eu³⁺, Tb³⁺, Er³⁺, Sm³⁺, Nd³⁺, Ho³⁺And Yb³⁺And halogen atoms such as F and Cl; and the like, and an effect such as exhibiting sharp emission characteristics with a narrow emission wavelength width can be provided.
[0044]
When the inorganic fine particles are compound semiconductor fine particles, the primary particle diameter of the fine particles is preferably 100 nm or less, from the viewpoint of high dispersion stability of the obtained inorganic fine particle dispersion, more preferably 50 nm or less, and still more preferably. Is 10 nm or less. If the particle diameter of the compound semiconductor fine particles exceeds 100 nm, the particles once dispersed may be re-precipitated by gravity.
When the inorganic fine particles are a metal, examples of the metal include a Group 8 metal such as Fe, Co, Ni, Pd and Pt, a Group 1B metal such as Cu, Ag and Au, Al, Ga and In. Group 3B metal such as Si, Ge and Sn, group 5B metal such as P and Bi, and group 6B metal such as Se and Te.
[0045]
When the inorganic fine particles are a metal oxide, examples of the metal oxide include various metal oxides (single oxide, composite oxide, and solid solution oxide) conventionally known in this technical field. it can.
The mixture referred to in the second method may contain other components in addition to the secondary aggregate of inorganic fine particles and the solvent described above.
In the second method, a specific compound, that is, a carboxylic acid, a halide ion, and a compound that generates a halide ion in the mixture are added to the mixture containing the secondary aggregate of the inorganic fine particles and the solvent described above. At least one member selected from the group is added so as to be present. As a result, the above-described problem can be solved at once and easily.
[0046]
In the second method, the method for causing the specific compound to be present in a mixture containing a secondary aggregate of inorganic fine particles and a solvent is not particularly limited. The timing of using the specific compound (the timing of addition) is not particularly limited, as long as it is finally present in the mixture. For example, a secondary aggregate of inorganic fine particles and a solvent are mixed. Where the specific compound may be added, or the specific compound may be added to a secondary aggregate of inorganic fine particles in advance and mixed with a solvent, or the specific compound may be previously added to the solvent. In addition, it may be mixed with inorganic fine particles.
[0047]
Although it does not specifically limit as said carboxylic acid, For example, aliphatic saturated monocarboxylic acids, such as formic acid, acetic acid, propionic acid, butyric acid, lauric acid, and stearic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, and adipine Aliphatic saturated dicarboxylic acids such as acid and sebacic acid; aliphatic unsaturated (mono, di, polyvalent) carboxylic acids such as acrylic acid, propiolic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid and mesaconic acid; Carbocyclic (mono, di, polyvalent) carboxylic acids such as acids, phthalic acid, terephthalic acid and naphthoic acid, toluic acid, hydroatropic acid and cinnamic acid; furic acid, tenic acid, nicotinic acid and isonicotinic acid, hydroxy Carboxylic acids, heterocyclic carboxylic acids such as alkoxycarboxylic acids; glycolic acid, lactic acid, glyceric acid, malic acid, Stone acid, benzyl acid, salicylic acid, 3,4-dihydroxybenzoic acid, anisic acid, such as piperonyl acid preferred. Among them, an aliphatic saturated monocarboxylic acid having 1 to 4 carbon atoms is more preferable in that it has a high ability to disperse impurities into solvent particles. These may be used alone or in combination of two or more.
[0048]
Although it does not specifically limit as said halide ion, For example, a fluoride ion (F⁻), Chloride ions (Cl⁻), Bromide ion (Br)⁻) And iodide ions (I⁻) And the like. These may be used alone or in combination of two or more.
The compound that generates halide ions in the mixture is not particularly limited, but includes hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide, and aqueous solutions thereof, and alkali metals and alkaline earth metals. And the like. These may be used alone or in combination of two or more.
[0049]
In the second method, the ratio (blending ratio) in which the above-described specific compound is added to the mixture containing the secondary aggregate of the inorganic fine particles and the solvent is not particularly limited, but is, for example, included in the mixture. The molar ratio is preferably from 0.001 to 10, more preferably from 0.01 to 0.1, based on the number of metal atoms of the inorganic fine particles. When the molar ratio is less than 0.001, the effect of separating and dispersing as primary particles may be insufficient. When the molar ratio is more than 10, the dispersing effect may be reduced or a specific compound may be used. This may adversely affect various fine particle characteristics such as optical characteristics and electrical characteristics of the inorganic fine particles.
[0050]
In the second method, when the above-mentioned specific compound is present in the mixture, the mixture may be stirred or heated. The effect of separating and dispersing secondary aggregates of inorganic fine particles as primary particles by stirring or heating can be further promoted. The method and conditions of stirring and heating are not particularly limited, and can be appropriately adopted and set. The temperature at the time of heating is not particularly limited, but may be, for example, 50 ° C or more and less than 300 ° C. Preferably, the temperature is more preferably higher than the boiling point of the solvent.
In the inorganic fine particle dispersion obtained by performing the second method, the dispersed particle size of the inorganic fine particles is not particularly limited, but is preferably 10 nm to 1 μm, more preferably 10 nm to 200 nm, and further preferably 10 nm to 50 nm. When powdery inorganic fine particles are obtained from the obtained inorganic fine particle dispersion by, for example, drying after removing the solvent, the specific surface area diameter (primary particle diameter) of the fine particles is not particularly limited. Is preferably 1 to 100 nm, more preferably 50 nm or less, and still more preferably 10 nm or less.
[0051]
By performing the second method, the inorganic fine particles that form the secondary aggregate can be economically, efficiently, and easily separated as primary particles and dispersed in a solvent. Dispersions can be manufactured economically, efficiently and easily. The inorganic fine particle dispersion obtained by the second method is, for example, R.I. G. FIG. B. Fluorescent and luminescent materials such as phosphor particles and luminescent particles, magnetic materials such as magnetic paints and magnetic fluids, conductive materials such as conductive paste and conductive ink, dielectric and insulating materials such as dielectric paste and insulating paste, etc. It can be usefully and suitably used as a (raw material) dispersion of various functional films and wiring materials.
[0052]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto. In the following, “parts by weight” may be simply referred to as “parts” and “% by weight” may be referred to as “wt%” for convenience.
Hereinafter, various analysis and measurement methods in Examples and Comparative Examples will be described.
(Elemental analysis)
Elemental analysis was performed by X-ray fluorescence analysis and / or inductively coupled plasma emission analysis.
[0053]
The X-ray fluorescence analysis was measured by a glass bead method using an X-ray fluorescence analyzer (PW2404, manufactured by Spectris Co., Ltd.).
For inductively coupled plasma emission analysis, a high-speed automatic analysis type hot water coupled plasma emission analyzer (manufactured by Seiko Denshi Kogyo Co., Ltd., SPS4000) is used. ,It was measured.
(Dispersion particle size)
It was measured by a dynamic light scattering particle size distribution analyzer (LB-500, manufactured by Horiba, Ltd.).
[0054]
[Specific surface area diameter]
B. E. FIG. T. From the specific surface area S obtained by the measurement according to the method, the particle diameter D obtained by the following equation was defined as the specific surface area diameter (corresponding to the primary particle diameter).
D = 6000 / [ρ · S]
(However, ρ: true specific gravity, S: specific surface area (m²/ G), unit of D: nm)
<Example according to the first invention>
(Method of cleaning inorganic solids)
-Example 1-
The compact of the CdSe polycrystal was crushed and further crushed in a mortar to obtain crushed particles having a particle diameter of about 0.5 to 2 μm. After mixing 100 parts of the particles, 500 parts of xylene and 0.03 part of acetic acid (acetic acid / Cd = 0.1 mol%), the mixture was allowed to stand overnight.
[0055]
After standing, the mixture was filtered under pressure using a filter having a pore size of 0.1 μm to obtain a filtrate component and a particle component. By drying the particles, 99 parts of CdSe powder was obtained.
The raw material CdSe polycrystal and the obtained CdSe powder were subjected to quantitative analysis based on the results of elemental analysis by fluorescent X-ray analysis and inductively coupled plasma emission analysis. The results are shown below.
Cu content in raw material CdSe: 1.3 ppm (Cu / CdSe)
Cu content in CdSe powder: less than 0.5 ppm (Cu / CdSe)
The dispersion (fine particles) contained in the filtrate was observed with a FE-TEM (field emission transmission electron microscope) provided with an XMA apparatus (X-ray microanalyzer) having a resolution of 1 nmφ, and the dispersion was observed. As a result of elemental analysis of the substance, it was confirmed that Cu fine particles and CuSe fine particles having a particle diameter of 10 to 20 nm were dispersed in the filtrate.
[0056]
-Comparative Example 1-
A CdSe powder was obtained in the same manner as in Example 1 except that acetic acid was not used.
Elemental analysis and quantitative analysis of the raw material CdSe polycrystal and the obtained CdSe powder as in Example 1 are shown below.
Cu content in raw material CdSe: 1.3 ppm (Cu / CdSe)
Cu content in CdSe powder: 1.3 ppm (Cu / CdSe)
<Example according to the second invention>
(Dispersion method of inorganic fine particles)
Example 2
The molded body of the polycrystalline zinc sulfide (ZnS) was crushed, and the pulverized product preliminarily pulverized in a mortar was filtered with a 100 mesh filter. 100 parts of ZnS powder passed through the filter and 100 parts of propylene glycol monomethyl ether acetate were mixed. The obtained mixture was charged into an alumina pot for a ball mill together with 200 parts of alumina balls having various particle diameters of 1 mmφ to 10 mmφ, and sealed. After setting the pot on a paint shaker, the pot was treated for 10 hours under the condition of an amplitude of 5 (vibration 5 times per second).
[0057]
The obtained content was subjected to pressure filtration with a filter having a pore size of 1 μm to obtain 190 parts of a slurry containing 52 wt% of ZnS fine particles. To 190 parts of the slurry, 6 parts of propylene glycol monomethyl ether acetate containing 10% by weight of acetic acid (acetic acid: 0.6 parts (acetic acid / Zn = 1 mol%)) was added and mixed, and the mixture was stirred overnight (stirred). Required power: 0.01 kW / m³) To obtain a dispersion of ZnS fine particles.
As a result of measuring the dispersed particle diameter (average particle diameter) of the ZnS fine particles in the obtained dispersion, it was 80 nm. In addition, the obtained dispersion was vacuum-dried to distill off the solvent to obtain ZnS fine particle powder. It was 85 nm as a result of measuring the specific surface area diameter of the obtained ZnS fine particle powder.
[0058]
-Comparative Example 2-
A dispersion liquid of ZnS fine particles and a ZnS fine particle powder were obtained in the same manner as in Example 2 except that acetic acid was not used in Example 2.
As a result of measuring the dispersed particle diameter (average particle diameter) of the ZnS fine particles in the obtained dispersion, it was 0.5 μm. The specific surface area diameter of the ZnS fine particle powder was measured to be 90 nm.
[0059]
【The invention's effect】
According to the method for cleaning an inorganic solid according to the first invention, in a mixture containing an inorganic solid containing an impurity and a solvent, the impurity can be economically, efficiently, and easily separated from the inorganic solid. Method can be provided.
According to the method for dispersing inorganic fine particles according to the second aspect of the present invention, in a mixture containing a secondary aggregate of inorganic fine particles and a solvent, the inorganic fine particles forming the secondary aggregate can be economically, efficiently and easily removed. It is possible to provide a novel method that can be dispersed in a solvent as the next particles, and thus to provide a method for economically, efficiently and easily producing an inorganic fine particle dispersion from the mixture.

Claims (8)

In a mixture containing an inorganic solid containing impurities and a solvent, a carboxylic acid, a halide ion, and at least one selected from the group consisting of compounds that generate a halide ion in the mixture are present, whereby the inorganic solid is formed. Separating the impurities from and cleaning the inorganic solid,
A method for cleaning inorganic solids, characterized in that: The method for cleaning an inorganic solid according to claim 1, wherein the inorganic solid is a compound semiconductor. The method for cleaning an inorganic solid according to claim 1 or 2, wherein the inorganic solid is a polycrystalline body. The inorganic solid is a compound semiconductor MX (where X is at least one element selected from the group consisting of C, Si, Ge, Sn, Pb, N, P, As, S, Sb, Se and Te). , M is at least one metal element that is not the same as X)).
The impurities are M, X and Mp segregated at crystallite grain boundaries of the polycrystal (where Mp is at least one type of metal element that is not the same as X and is a metal element different from M) And at least one selected from the group consisting of compound semiconductors Mp-X.
The method for cleaning an inorganic solid according to any one of claims 1 to 3. The method for cleaning an inorganic solid according to any one of claims 1 to 4, wherein the inorganic solid containing the impurities is mechanically refined. In a mixture containing a secondary aggregate of inorganic fine particles and a solvent, a carboxylic acid, a halide ion, and the presence of at least one selected from the group consisting of compounds that generate a halide ion in the mixture are present. Dispersing inorganic fine particles as the primary particles in the solvent,
A method for dispersing inorganic fine particles, characterized in that: The method for dispersing inorganic fine particles according to claim 6, wherein the inorganic fine particles are fine particles made of a compound semiconductor. The method for dispersing inorganic fine particles according to claim 6, wherein a primary particle diameter of the inorganic fine particles is 100 nm or less.