Method for removing metals from polysilane compounds

Abstract

To provide: a purification method of a polysilane compound, with which a metal is efficiently removed from the polysilane compound without occurrence of new metal contamination; in addition, a purification method of a polysilane compound, with which a content of a metal component is further significantly reduced from the polysilane compound having the metal component removed with a conventional method; and further a high purity polysilane compound having a significantly reduced content of the metal component.SOLUTION: A purification method of a polysilane compound at least has a preparation step to dilute a polysilane compound containing metal impurities with a compound having at least one amide group skeleton, and a metal removal step to remove the metal impurities to the outside of the system with a metal removal treatment from the diluted polysilane compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a purification method for removing metal components contained in polysilane compounds, and to polysilanes obtained by removing the metal components using this purification method. [Background technology]

[0002] Polysilane compounds are materials with silicon as the main chain, and are water-repellent, rust-resistant, anti-oxidant, highly heat-resistant, have a high refractive index, and are photoreactive. They are attracting attention as ceramic precursors and optoelectronic materials (for example, photoresists, optoelectronic photographic materials such as organic photoreceptors, optical transmission materials such as optical waveguides, optical recording materials such as optical memory, and materials for electroluminescent devices).

[0003] A typical method for synthesizing polysilane compounds is to use an alkali metal such as metallic sodium to vigorously stir a dialkyldihalosilane or dihalotetraalkyldisilane in a toluene solvent at a temperature of 100°C or higher to cause reductive coupling [Non-Patent Document 1, commonly known as the "Kipping method"]. However, this method requires heating an alkali metal that ignites in air and vigorously stirring and dispersing it, raising safety concerns in industrial-scale production. In addition, the molecular weight distribution becomes multimodal, which may result in insufficient quality depending on the application.

[0004] As a method for solving these problems, for example, Patent Documents 1 and 2 disclose methods for obtaining polysilanes by polymerizing halosilanes using a magnesium component. The methods described in these documents involve polymerization using a magnesium component alone, or a magnesium component and a metal halide as a catalyst, and have the following excellent features: (1) synthesis can be performed using stable and inexpensive raw materials using a general-purpose chemical synthesis apparatus, making them advantageous in terms of safety and cost; (2) no impurities (such as sodium or substances insoluble in organic solvents) that are unsuitable for use as optoelectronic materials are mixed in; (3) polysilanes can be obtained that have little variation in molecular weight and are highly soluble in organic solvents and highly transparent; and (4) high yields.

[0005] However, in both of the above two methods, as well as in any other conventional methods for producing polysilane compounds, metals or metal salts are usually always used, and metal components remain in the polysilane compound, which may make it unsuitable for use as an optoelectronic material.

[0006] Furthermore, in Patent Document 3, metal removal treatment is performed by washing with a CuCl2 aqueous solution or an FeCl3 aqueous solution. However, although Zn, which has a high ionization tendency, is efficiently removed, it can also cause Cu contamination.

[0007] Polysilane compounds with many terminal structures, which are made from trihalosilane compounds or tetrahalosilane compounds as raw materials, appear to be particularly prone to incorporating metal components into their structures, although the details of the mechanism are unknown. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 98 / 29476 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-277507 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-162792 [Non-patent literature]

[0009] [Non-Patent Document 1] J. Am. Chem. Soc., 103 (1981) 7352 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a method for purifying a polysilane compound, which can efficiently remove metals from the polysilane compound without generating new metal contamination. The present invention also provides a method for purifying a polysilane compound, which can further significantly reduce the content of metal components in a polysilane compound from which metal components have been removed by a conventional method. The present invention further provides a high-purity polysilane compound with a significantly reduced content of metal components. [Means for solving the problem]

[0011] In a first aspect, the present invention relates to a method for purifying a polysilane compound, the method comprising at least a preparation step of diluting a polysilane compound containing metal impurities with at least one compound having an amide group skeleton, and a metal removal step of subjecting the diluted polysilane compound to a metal removal treatment to remove the metal impurities from the system. As a second aspect, the present invention relates to a method for purifying a polysilane compound according to the first aspect, wherein the polysilane compound is a compound having at least one structural unit selected from structural units represented by the following formulas (1) to (3) and has a weight-average molecular weight of 50 to 30,000: [ka] (In the formula, R is a hydrogen atom, a hydroxy group, a silyl group, or an organic group, and n is an integer of 1 or more.) As a third aspect, the present invention relates to the method for purifying a polysilane compound according to the second aspect, in which the silyl group is a silanyl group having 1 to 6 silicon atoms, and the organic group is an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms. As a fourth aspect, the present invention relates to the method for purifying a polysilane compound according to any one of the first to third aspects, wherein the compound having an amide group skeleton is a compound having a structure represented by the following formula (4): [ka] (In the formula, R1, R2, and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an ether group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms; or R1 and R2 may combine to form a ring, in which case R1 may represent an amino group optionally substituted with an alkyl group having 1 to 10 carbon atoms.) As a fifth aspect, the R1, R2, and R3 are each independently a hydrogen atom, a group having 1 carbon atom, or R1 and R2 may be bonded to form a ring, in which case R1 may represent an amino group optionally substituted with an alkyl group having 1 to 5 carbon atoms. As a sixth aspect, the present invention relates to the method for purifying a polysilane compound according to the fourth aspect, in which the compound having an amide group skeleton is N-methylpyrrolidone, N-ethylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropanamide, N,N-dimethylformamide, N,N-dimethylacetamide, or N,N-dimethylisobutyramide. As a seventh aspect, the present invention relates to the method for purifying a polysilane compound according to any one of the first to sixth aspects, wherein the metal removal treatment is a treatment for removing metal impurities using an ion exchange resin or a chelating resin. As an eighth aspect, the present invention relates to the method for purifying a polysilane compound according to any one of the first to seventh aspects, wherein the ion exchange resin is a mixture of a cation exchange resin and an anion exchange resin. As a ninth aspect, the present invention relates to the method for purifying a polysilane compound according to the eighth aspect, in which the cation exchange resin is a resin having a structure of the following formula (6), and the anion exchange resin is a resin having a structure of the following formula (7) or a structure of formula (8): [ka] As a tenth aspect, the present invention relates to the method for purifying a polysilane compound according to any one of the first to ninth aspects, wherein the chelating resin is a polymeric substance having a unit structure represented by the following formula (A-1), or a polymeric substance having at least one unit structure selected from the group consisting of unit structures represented by the following formulas (B-1) to (B-4): [ka] (wherein n represents an integer of 1 to 10, and A 1 is a unit structure constituting silica, a silica component-containing substance, polystyrene, or cross-linked porous polystyrene as a carrier, and A 2 is a single bond or A 1 and a functional group, and the linking group represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, a nitrogen atom, or a sulfur atom. [ka] (In the formula, B 1 is a unit structure constituting silica, a silica component-containing substance, polystyrene, or cross-linked porous polystyrene as a carrier, and B 2 is a single bond or B 1 and the thiourea group or thiouronium group, and the linking group is an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, a nitrogen atom, or a sulfur atom; B 3 is a phenyl group which may be substituted with a hydroxyl group and / or an alkyl group having 1 to 3 carbon atoms. As an eleventh aspect, the present invention relates to the method for purifying a polysilane compound according to any one of the first to tenth aspects, in which the metal impurity is at least one kind selected from the group consisting of Mg, Cu, Zn, Cr, and Fe. As a twelfth aspect, the present invention relates to a method for purifying a polysilane compound according to any one of the first to eleventh aspects, in which the amount of the metal impurities is reduced to 2 ppm or less in terms of 100 mass % of the polysilane compound. As a thirteenth aspect, the present invention relates to a purified polysilane compound in which the amount of remaining metal impurities is 2 ppm or less calculated as 100% by mass of the polysilane compound, the polysilane compound having at least one structural unit selected from structures represented by the following formulas (1) to (3) and having a weight-average molecular weight of 50 to 30,000: [ka] (In the formula, R is a hydrogen atom, a hydroxy group, a silyl group, or an organic group, and n is an integer of 1 or more.) According to a fourteenth aspect, the present invention relates to the purified polysilane compound according to the thirteenth aspect, in which the silyl group is a silanyl group having 1 to 6 silicon atoms, and the organic group is an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms. According to a fifteenth aspect, the present invention relates to the purified polysilane compound according to the thirteenth or fourteenth aspect, in which the metal impurity is at least one selected from the group consisting of Mg, Cu, Zn, Cr, and Fe. [Effects of the Invention]

[0012] According to the method for purifying polysilane compounds of the present invention, no new metal components are used, and therefore no contamination of new metal components occurs. Furthermore, in the method for purifying polysilane compounds of the present invention, the polysilane compound is diluted with a compound having an amide group skeleton and then brought into contact with a chelating resin or an ion exchange resin, thereby efficiently removing metal components that are already contained in the polysilane compound to be purified without significantly changing the molecular weight of the polysilane compound, and this is different from the conventional method for purifying polysilane compounds. The removability is improved compared to conventional methods for purifying polysilane compounds. Furthermore, the method of the present invention allows for simple and efficient removal of metal components, such as zinc, even from polysilanes from which metal components are difficult to remove using conventional methods (e.g., washing with a solvent). Furthermore, the method of the present invention allows for a further significant reduction in the metal component content from polysilane compounds from which metal components have been removed using conventional methods (e.g., washing with a CuCl2 aqueous solution or an FeCl3 aqueous solution). The polysilane compounds obtained by such methods are high-purity polysilanes with significantly reduced metal component content, and are therefore suitable for applications requiring reduced metal component content, such as optoelectronic materials. Furthermore, because the metal component content is significantly reduced, deterioration of the polysilane can be suppressed over a long period of time. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention provides a method for purifying a polysilane compound, which comprises at least a preparation step of diluting a polysilane compound containing metal impurities with at least one compound having an amide group skeleton, and a metal removal step of subjecting the diluted polysilane compound to a metal removal treatment to remove the metal impurities from the system.

[0014] [Polysilane compounds] The polysilane is not particularly limited as long as it is a linear, cyclic, branched, or network compound having an Si-Si bond. Generally, the polysilane is often composed of a polysilane having at least one structural unit selected from the structural units represented by the following formulas (1) to (3).

[0015] [ka] (In the formula, R is a hydrogen atom, a hydroxy group, a silyl group, or an organic group, and n is an integer of 1 or more.)

[0016] In the formulas (1) and (2), examples of the organic group represented by R include hydrocarbon groups (alkyl groups, alkenyl groups, cycloalkyl groups, cycloalkenyl groups, aryl groups, and aralkyl groups), ether groups corresponding to these hydrocarbon groups (alkoxy groups, cycloalkyloxy groups, aryloxy groups, and aralkyloxy groups), hydroxyl groups, and optionally substituted amino groups (for example, amino groups (-NH), substituted amino groups (N-mono- or N,N-di-substituted amino groups substituted with the alkyl groups, cycloalkyl groups, aryl groups, aralkyl groups, acyl groups, and the like)). These substituents may be further substituted with one or more other substituents [for example, the above-exemplified substituents such as a hydrocarbon group such as an alkyl group (e.g., an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms), an alkoxy group (e.g., an alkoxy group having 1 to 10 carbon atoms, preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms), or an acyl group (e.g., an alkyl-carbonyl group having 1 to 10 carbon atoms such as an acetyl group, preferably an alkyl-carbonyl group having 1 to 6 carbon atoms, more preferably an alkyl-carbonyl group having 1 to 4 carbon atoms)].

[0017] In R of the formula (1) and formula (2), examples of the alkyl group include alkyl groups having 1 to 14 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, and hexyl (preferably alkyl groups having 1 to 10 carbon atoms, and more preferably alkyl groups having 1 to 6 carbon atoms).

[0018] Examples of the alkoxy group include alkoxy groups having 1 to 14 carbon atoms (preferably alkoxy groups having 1 to 10 carbon atoms, more preferably alkoxy groups having 1 to 6 carbon atoms), such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, and pentyloxy.

[0019] Examples of the alkenyl group include alkenyl groups having 2 to 14 carbon atoms, such as vinyl, allyl, butenyl, and pentenyl (preferably alkenyl groups having 2 to 10 carbon atoms, and more preferably alkenyl groups having 2 to 6 carbon atoms).

[0020] Examples of the cycloalkyl group include a cycloalkyl group having 5 to 14 carbon atoms such as cyclopentyl, cyclohexyl, and methylcyclohexyl (preferably a cycloalkyl group having 5 to 10 carbon atoms, more preferably a cycloalkyl group having 5 to 8 carbon atoms). Examples of the cycloalkyloxy group include a cycloalkyloxy group having 5 to 14 carbon atoms such as cyclopentyloxy and cyclohexyloxy (preferably a cycloalkyloxy group having 5 to 10 carbon atoms, more preferably a cycloalkyloxy group having 5 to 8 carbon atoms). Examples of the cycloalkenyl group include a cycloalkenyl group having 5 to 14 carbon atoms such as cyclopentenyl and cyclohexenyl (preferably a cycloalkenyl group having 5 to 10 carbon atoms, more preferably a cycloalkenyl group having 5 to 8 carbon atoms).

[0021] Examples of the aryl group include aryl groups having 6 to 20 carbon atoms, such as phenyl, methylphenyl (tolyl), dimethylphenyl (xylyl), and naphthyl (preferably an aryl group having 6 to 15 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms). Examples of the aryloxy group include aryloxy groups having 6 to 20 carbon atoms, such as phenoxy and naphthyloxy (preferably an aryloxy group having 6 to 15 carbon atoms, more preferably an aryloxy group having 6 to 12 carbon atoms). Examples of the aralkyl group include aryl-C1-C4 alkyl groups having 6 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl (preferably an aryl-C1-C2 alkyl group having 6 to 10 carbon atoms). Examples of the aralkyloxy group include aryl-C1-C4 alkyloxy groups having 6 to 20 carbon atoms, such as benzyloxy, phenethyloxy, and phenylpropyloxy (preferably an aryl-C1-C2 alkyloxy group having 6 to 10 carbon atoms).

[0022] Examples of the silyl group include silanyl groups having 1 to 10 silicon atoms (preferably silanyl groups having 1 to 6 silicon atoms), such as a silyl group, a disilanyl group, and a trisilanyl group.

[0023] Typically, the group R may be a hydrocarbon group (a hydrocarbon group which may have a substituent) or an ether group corresponding to the hydrocarbon group (an ether group to which a hydrocarbon group which may have a substituent is bonded or substituted). Preferred groups R include hydrocarbon groups such as alkyl groups, cycloalkyl groups, and aryl groups, and alkyl groups (e.g., alkyl groups having 1 to 4 carbon atoms, such as methyl groups) or aryl groups (e.g., aryl groups having 6 to 10 carbon atoms, such as phenyl groups) are particularly preferred. The substituents R may be the same or different.

[0024] When polysilane has a non-cyclic structure (straight-chain, branched-chain, or network structure), the terminal group (terminal substituent) is usually a hydrogen atom, a hydroxyl group, a halogen atom (such as a chlorine atom), an alkyl group, or an alkyl group. It may also be an alkoxy group, a silyl group, or the like.

[0025] Specific examples of polysilanes include branched-chain polysilanes (or network polysilanes) having a structural unit represented by formula (1), linear polysilanes having a structural unit represented by formula (2), cyclic polysilanes having a structural unit represented by formula (3), and branched polysilanes having a combination of structural units represented by formulas (1) to (3). When the polysilane is a copolymer, it may be either a block copolymer or a random copolymer. Furthermore, the polysilane may be a polysilane having each of the structural units represented by formulas (1) to (3) alone or in combination of two or more of them.

[0026] Linear polysilanes having a structural unit represented by formula (2) have properties such as superior solvent solubility compared to branched polysilanes having a structural unit represented by formula (1) or cyclic polysilanes having a structural unit represented by formula (3), making them suitable for a wide range of applications. Furthermore, polysilanes having a structural unit represented by formula (1) tend to incorporate metal components, making them difficult to remove, likely due to their branched structure. The present invention can efficiently remove metal components contained in polysilanes having either a linear or branched structure.

[0027] In the branched polysilane, the proportion of the branched structural unit, calculated in terms of silicon atoms (molar) constituting the polysilane, may be, for example, 1 mol % or more (e.g., 3 to 100 mol %), preferably 5 mol % or more (e.g., about 10 to 95 mol %), and more preferably 15 mol % or more (e.g., about 20 to 90 mol %) of the entire polysilane.

[0028] Representative polysilanes include, for example, polydialkylsilanes [e.g., polydialkylsilanes having 1 to 6 carbon atoms, such as polydimethylsilane, polymethylpropylsilane, polymethylbutylsilane, polymethylpentylsilane, polydibutylsilane, polydihexylsilane, and dimethylsilane-methylhexylsilane copolymers, preferably polydialkylsilanes having 1 to 4 carbon atoms], polyalkylarylsilanes [e.g., polyarylsilanes having 6 to 15 alkyl carbon atoms, such as polymethylphenylsilane and methylphenylsilane-phenylhexylsilane copolymers, preferably polyarylsilanes having 6 to 10 alkyl carbon atoms, such as polydiphenylsilane], polydiarylsilanes (e.g., polyarylsilanes having 6 to 15 carbon atoms, such as polydiphenylsilane, preferably polyarylsilanes having 6 to 10 carbon atoms), and polydiarylsilanes (e.g., polyarylsilanes having 6 to 15 carbon atoms, such as polydiphenylsilane, preferably polyarylsilanes having 6 to 10 carbon atoms). polysilanes having a structural unit represented by the formula (1), such as dialkylsilane-alkylarylsilane copolymers (e.g., dialkylsilane-alkylarylsilane copolymers having 1 to 6 carbon atoms, such as dimethylsilane-methylphenylsilane copolymer, dimethylsilane-phenylhexylsilane copolymer, and dimethylsilane-methylnaphthylsilane copolymer, preferably dialkylsilane-alkylarylsilane copolymers having 1 to 6 carbon atoms, such as dimethylsilane-methylphenylsilane copolymer, dimethylsilane-phenylhexylsilane copolymer, and dimethylsilane-methylnaphthylsilane copolymer), and the like; branched polysilanes having a structural unit represented by the formula (2) or the formula (3), such as polyarylsilanes (e.g., polyarylsilanes having 6 to 15 carbon atoms, such as polyphenylsilane (polyphenylsilane), preferably polyarylsilanes having 6 to 10 carbon atoms);The structural units represented by the formula (1) include dialkylsilane-arylsilane copolymers (e.g., a copolymer of a dialkylsilane having 1 to 6 carbon atoms and an arylsilane having 6 to 15 carbon atoms, such as a dimethylsilane-phenylsilane copolymer, preferably a copolymer of a dialkylsilane having 1 to 6 carbon atoms and an arylsilane having 6 to 10 carbon atoms), alkylarylsilane-arylsilane copolymers (e.g., a copolymer of an alkylsilane having 1 to 6 carbon atoms and an arylsilane having 6 to 15 carbon atoms, such as a methylphenylsilane-phenylsilane copolymer, preferably ...0 carbon atoms); and a branched polysilane having a structural unit represented by formula (2) or a structural unit represented by formula (3). Details of such polysilanes are exemplified, for example, by R.D. Miller, J. Michl; Chemical Review, Vol. 89, p. 1359 (1989) and N. Matsumoto; Japanese Journal of Physics, Vol. 37, p. 5425 (1998). The polysilane may also be a copolymer of a polysilane raw material (such as a halosilane) and a vinyl compound. Details of such copolymers are disclosed, for example, in JP-A-2002-128897.

[0029] These polysilanes can be used alone or in combination.

[0030] The molecular weight of the polysilane may be, in terms of weight average molecular weight, about 50 to 30,000, preferably about 300 to 20,000, and more preferably about 400 to 10,000. When the polysilane is cyclic, the number of ring members of the cyclic polysilane may usually be about 4 to 12, preferably about 4 to 10, and more preferably about 5 to 10 (particularly about 5 to 8).

[0031] Polysilanes may be commercially available or prepared by various known methods. A typical method for synthesizing polysilanes involves vigorously stirring dialkyldihalosilanes or dihalotetraalkyldisilanes in a toluene solvent at temperatures above 100°C using an alkali metal such as metallic sodium, resulting in reductive coupling [J. Am. Chem. Soc., 103 (1981) 7352]. However, this method requires heating an alkali metal that ignites in air and vigorously stirring and dispersing the mixture, raising safety concerns in industrial-scale production. Furthermore, the resulting polysilanes have a multimodal molecular weight distribution, which may result in insufficient quality for certain applications.

[0032] Other methods for producing polysilanes include (a) anionic polymerization of disilene masked with biphenyl or the like (Japanese Patent Laid-Open Publication No. 1-23063), (b) ring-opening polymerization of cyclic silanes (Japanese Patent Laid-Open Publication No. 5-170913), (c) dehydrogenative condensation polymerization of hydrosilanes using a transition metal complex catalyst (Japanese Patent Laid-Open Publication No. 7-17753), (d) electrochemical reduction of dihalosilanes at a temperature below room temperature to produce polysilanes (Japanese Patent Laid-Open Publication No. 7-309953), and (e) dehalogenative condensation polymerization of halosilanes using magnesium as a reducing agent (the so-called "magnesium reduction method"; for example, the methods described in WO98 / 29476, Japanese Patent Laid-Open Publication No. 2003-277507, and Japanese Patent Laid-Open Publication No. 2005-36139).

[0033] In particular, the magnesium reduction method has the following excellent features: (1) it can be synthesized using stable and inexpensive raw materials using general-purpose chemical synthesis equipment, making it advantageous in terms of safety and cost; (2) it does not contain impurities such as sodium and substances insoluble in organic solvents that are unsuitable for use in optical and electronic materials; (3) it produces polysilanes with little variation in molecular weight, high solubility in organic solvents, and high transparency; and (4) it produces polysilanes in high yield.

[0034] Therefore, polysilanes obtained by a magnesium reduction method may be preferably used. In such a magnesium reduction method, polysilanes can be synthesized by polymerizing halosilanes in the presence of at least a magnesium metal component. In particular, in the magnesium reduction method, in order to obtain high-performance polysilanes more efficiently, magnesium metal components are often used in combination with other metal components [e.g., lithium compounds, metal halides (metal halides other than lithium compounds (lithium halides, lithium halides)]] as catalysts.

[0035] Polysilanes obtained by these various methods (especially by the magnesium reduction method) The resulting polysilanes are produced using various metal components as catalysts, and these catalysts are often the cause of the inclusion of metal components in the polysilanes.

[0036] [Compounds with an amide group skeleton] The polysilane compound is diluted with at least one compound having an amide group skeleton before being treated to remove metals by the purification method of the present invention.

[0037] The compound having an amide group skeleton is a compound having a structure represented by the following formula (4): [ka] (In the formula, R1, R2, and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an ether group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms; or R1 and R2 may combine to form a ring, in which case R1 may represent an amino group optionally substituted with an alkyl group having 1 to 10 carbon atoms.)

[0038] Preferably, R1, R2, and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an ether group having 1 to 5 carbon atoms, or R1 and R2 may combine to form a ring, in which case R1 may represent an amino group optionally substituted with an alkyl group having 1 to 5 carbon atoms.

[0039] More specifically, the compounds having an amide group skeleton include the following compounds. [ka]

[0040] [Metal impurities] Metal impurities may be incorporated into polysilanes through any process, but are usually incorporated into polysilanes during the synthesis process. Examples of such metal impurities include (i) metal components (Mg, Cu, Zn, etc.) derived from metal catalysts that are incorporated into polysilanes by polymerizing raw materials for polysilanes in the presence of a metal catalyst; (ii) ) Metallic components contained in the raw materials of polysilanes are examples of such impurities. Usually, the majority of metallic impurities contained in polysilanes are metallic components derived from metal catalysts.

[0041] The metal impurities are not particularly limited and include various metal atoms (or metal ions), for example, alkali or alkaline earth metals (e.g., Na, Mg, etc.), transition metals (e.g., Group 3A elements of the periodic table such as Sm, Group 4A elements of the periodic table such as Ti, Group 5A elements of the periodic table such as V, Group 6A elements of the periodic table such as Cr, Group 8 elements of the periodic table such as Fe, Ni, Co, Pd, and Group 1B elements of the periodic table such as Cu), Group 2B elements of the periodic table (e.g., Zn, etc.), Group 3B metals of the periodic table (e.g., Al, etc.), and Group 4B metals of the periodic table (e.g., Sn, etc.). The metal impurities may be a single metal or may be composed of different metals.

[0042] Among these metal impurities, metals such as elements of Group 8 of the periodic table (particularly Fe) and elements of Group 2B of the periodic table (e.g., Zn) are effective as metals constituting polymerization catalysts for halosilanes, but are easily incorporated into polysilanes and are difficult to remove from polysilanes not only by conventional purification methods (e.g., washing with organic solvents, water, etc.) but also by washing with acids, alkalis, etc. The method of the present invention makes it possible to remove even such extremely difficult-to-remove metals from polysilanes at high levels.

[0043] The form in which the metal impurities are contained is not particularly limited, and for example, they may be incorporated into the polymer structure of the polysilane in the form of a metal compound, or may be bonded to the polysilane by coordination with a constituent atom of the polysilane (e.g., a silicon atom).

[0044] In the polysilane containing metal impurities, the proportion of the metal impurities is not particularly limited, but can be selected from a range of about 3 to 100,000 ppm, preferably about 3 to 10,000 ppm, more preferably about 3 to 5,000 ppm, and particularly preferably about 3 to 2,000 ppm, in terms of the weight of the metal, relative to the total. In the present invention, even polysilanes that already contain such large amounts of metal impurities can be efficiently removed.

[0045] Although the reason why metal impurities are incorporated into polysilane compounds is unclear, it is believed that metal impurities have some affinity for polysilane. Moreover, metal components (especially Fe, Zn, etc.) used as catalysts in polysilane synthesis have a high affinity (or residual tendency) for polysilane, probably because they are involved in polymerization. Once incorporated into polysilane and remain, methods such as washing (with solvents, acids, or alkalis) can remove some of the impurities, but it is difficult to remove them to a high degree.

[0046] Therefore, in the present invention, a polysilane compound containing metal impurities is diluted with at least one compound having an amide group skeleton, and the diluted polysilane compound is subjected to a metal removal treatment to efficiently remove the metal impurities from the system.

[0047] [Metal removal treatment] One example of a metal removal treatment method is to contact a polysilane compound containing a metal component with another metal component having a lower ionization tendency in the presence of a solvent. The metal removal treatment of the present invention is a treatment in which metal impurities are removed from the system by contacting the diluted polysilane compound with an ion exchange resin or a chelating resin.

[0048] [Ion exchange resin] An example of the ion exchange resin used in the present invention is one in which ion exchange groups are fixed to the surface of a porous carrier made of a styrene-divinylbenzene copolymer. Depending on the type of fixed exchange group, the resin is classified as either strongly acidic or weakly acidic. Strongly acidic resins include styrene-divinylbenzene copolymers. Examples of weakly acidic groups include carboxyl, phosphonic acid, phosphinic acid, arsenous acid, and phenoxide groups. Based on the physical properties of the carrier, they are classified into gel type and micro-reticular (MR) type, which is a gel-type resin with pores formed inside to make it porous.

[0049] The catalytic activity of ion exchange resins depends on the contact area between the reactant and the ion exchange resin surface and the type of functional group on the ion exchange resin surface. Without being bound by theory, gel-type ion exchange resins generally have only micropores (pore diameter: up to several tens of Å), so it is assumed that reactants with large molecular weights, such as polymers, have difficulty penetrating into the resin pores. MR-type ion exchange resins have mesopores and macropores (pore diameter: from several hundred Å), so even reactants with large molecular weights, such as polymers, can penetrate into the pores, and it is assumed that the contact area between the polymer and the ion exchange resin surface is relatively large. The ion exchange resin used in the present invention is preferably a mixture of a cation exchange resin and an anion exchange resin.

[0050] The ion exchange resin of the present invention is not particularly limited as long as it is a mixture of a cation exchange resin and an anion exchange resin, and commercially available products can be used. Preferably, the cation exchange resin is a styrene-based gel-type strongly acidic cation exchange resin having the structure of the following formula (6), and the anion exchange resin is a styrene-based macroporous strongly basic anion exchange resin having the structure of the following formula (7) or formula (8). [ka]

[0051] Examples of commercially available ion exchange resins include DS-1, a styrene-based gel-type strongly acidic cation exchange resin (trade name, manufactured by Organo Corporation), DS-4, a styrene-based macroporous strongly acidic cation exchange resin (trade name, manufactured by Organo Corporation), DS-2, a styrene-based gel-type strongly basic anion exchange resin (trade name, manufactured by Organo Corporation), DS-5, a styrene-based macroporous strongly basic type I anion exchange resin (trade name, manufactured by Organo Corporation), and DS-2, a styrene-based macroporous strongly basic type II anion exchange resin (manufactured by Muromachi Chemical Co., Ltd.).

[0052] The removal of metal impurities with an ion exchange resin can be carried out by treating a diluted polysilane compound containing metal impurities with the ion exchange resin in a batch system or a column flow system.

[0053] The batch method is a method in which the solution to be purified and ion exchange resin are stirred and mixed for a certain period of time, and then the resin is removed by filtration, etc. The column flow method is a method in which metal impurities are removed from the solution to be purified by passing the solution through a fixed bed such as a column or packed tower filled with ion exchange resin.

[0054] Comparing the batch method and column flow method, the contact between the solution to be purified and the ion exchange resin is generally From the viewpoint of catalytic efficiency, the column flow method allows treatment with ion exchange resin in a shorter time, and is therefore more effective in reducing the change in weight average molecular weight (ΔMw).

[0055] The treatment is usually performed once, but may be performed two or more times. The treatment time in the batch process varies depending on the type and amount of the polysilane compound to be purified, the ion exchange resin, and the solvent used. Similarly, the liquid flow rate in the column flow process varies depending on the type and amount of the polysilane compound to be purified, the ion exchange resin, and the solvent used. These conditions can be easily optimized by those skilled in the art through routine experiments.

[0056] The amount of ion exchange resin used in the present invention depends on the type of polysilane compound to be purified and the type of organic solvent used, but is usually about 0.01 to 1000% by mass, preferably 0.1 to 500% by mass, and more preferably 1 to 100% by mass, of the amount of polysilane compound to be purified.

[0057] [Chelating resin] The chelating resin used in the present invention is preferably a polymeric substance having a unit structure represented by the following formula (A-1) or a polymeric substance having at least one unit structure selected from the group consisting of unit structures represented by the following formulae (B-1) to (B-4) (hereinafter, these will also be referred to as the chelating agent (chelating resin) of formula (A-1), the chelating agent (chelating resin) of formulae (B-1) to (B-4), or simply formula (A-1), formulae (B-1) to (B-4), etc.).

[0058] [ka] [ka]

[0059] In the unit structure of formula (A-1), A 1 is a unit structure constituting silica, a silica component-containing substance, polystyrene, or cross-linked porous polystyrene as a carrier, and the glucamine type functional group is A 2 via A 1 In the glucamine-type functional group, n is an integer of 1 to 10. In particular, a structure in which n is 2 to 5, or 3 to 5, and particularly n=4 is preferred. A 2 represents a single bond, or A 1 and a functional group, and the linking group may be an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, a nitrogen atom, or a sulfur atom. 2 via an alkylene group having 1 to 5 carbon atoms, or 1 to 3 carbon atoms, particularly 1 carbon atom, 1 Examples of such structures include those linked to

[0060] In the chelating resin of formula (A-1), the carrier is preferably polystyrene or crosslinked porous polystyrene. 1 An example of the unit structure is polystyrene. The chelating resin of formula (A-1) has higher selectivity for metal ions with higher valences. Chelating agents of formula (A-1) are available, for example, from Mitsubishi Chemical Corporation under the trade names CRB03 and CRB05.

[0061] In the unit structures of formulae (B-1) to (B-4), B 1 is a unit structure constituting silica, a silica component-containing substance, polystyrene, or cross-linked porous polystyrene as a carrier, and B 2 represents a single bond, or B 1 and a functional group, and the linking group is an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, a nitrogen atom, or a sulfur atom; B 3 The group B may be a phenyl group which may be substituted with a hydroxyl group and / or an alkyl group having 1 to 3 carbon atoms. 2 Examples of the hydrocarbon group include hydrocarbon groups having 1 to 10 carbon atoms, or 1 to 5 carbon atoms, and particularly 3 carbon atoms. 1 The porous material is preferably polystyrene or crosslinked porous polystyrene, and particularly preferably crosslinked porous polystyrene.

[0062] Chelating agents containing polymeric substances having the unit structures of formula (B-1) and formula (B-2) can capture many metals under various conditions, including metals such as Ca, Cd, Cr, Cs, Cu, Fe, Ir, La, Mg, Os, Pd, Pt, Rh, Ru, Sc, Sn, and Zn, as well as their metal hydroxide colloids and metal oxide colloids. They are particularly suitable for capturing Sn, its ions, and its metal hydroxide colloids and metal oxide colloids. The amount of functional groups can be approximately 0.1 to 5 mmol per gram of metal adsorbent. The chelating agent of formula (B-1) is available from Muromachi Chemical Co., Ltd. under the trade name Muromac XMS-5418. The chelating resin of formula (B-2) is available from Purolite Co., Ltd. under the trade name S920.

[0063] Chelating agents containing polymeric substances having unit structures of formula (B-3) and formula (B-4) are effective for capturing metals, metal ions, such as Ag, Cu, Fe, Os, Pd, Rh, Sc, and Sn, as well as their metal hydroxide colloids and metal oxide colloids. They are particularly effective for capturing palladium ions in organic solvents. The amount of functional groups can be approximately 0.1 to 5 mmol per gram of metal adsorbent. Formula (B-3) is available from Purolite Co., Ltd. under the trade name S914. Furthermore, the chelating resin of formula (B-4) is available from Muromachi Chemical Co., Ltd. under the trade name MuromacXMS-5812.

[0064] The amount of the chelating resin used in the present invention is adjusted depending on the type of chelating resin and the amount of metal ions, but is usually about 0.01 to 1000% by mass, preferably 0.1 to 500% by mass, and more preferably 1 to 100% by mass, of the amount of the polysilane compound to be purified.

[0065] In the present invention, the ion exchange resin and the chelating resin may be used in combination, and several types of chelating resins may be used in combination.

[0066] [Method for purifying polysilane compounds] The method for purifying a polysilane compound of the present invention comprises at least a preparation step of diluting a polysilane compound containing metal impurities with at least one compound having an amide group skeleton, and a metal removal step of removing the metal impurities from the system by subjecting the diluted polysilane compound to a metal removal treatment. The present invention also provides a method for preparing a solution of a material to be purified (a polysilane compound to be purified) by dissolving the material to be purified in the compound having at least one amide group skeleton, and a method for dissolving the material to be purified in the compound having the amide group skeleton together with the ion exchange resin or chelating resin (hereinafter also referred to as a metal adsorbent). The present invention also covers a method for purifying a material solution, which includes the steps of filling an ethylene container with the material solution to be purified and the metal adsorbent, stirring the solution containing the material to be purified and the metal adsorbent, and removing the metal adsorbent from the solution containing the material to be purified and the metal adsorbent to obtain a purified solution. The present invention also covers a method for purifying a material solution in which all of the above purification steps are carried out in a batch manner. The present invention also covers a method for purifying a material solution, which includes the steps of preparing a solution of the material to be purified by dissolving the material to be purified in the compound having at least one type of amide group skeleton, and passing the solution of the material to be purified through a column packed with the metal adsorbent to obtain a purified solution.

[0067] A solution of the material to be purified, prepared by dissolving the material to be purified in a compound having at least one amide group skeleton, contains metal impurities derived from the material to be purified at a concentration of several ppm to several hundred ppm. The purification method of the present invention makes it possible to reduce the metal impurities in the solution to 2 ppm or less at 100% by mass. Furthermore, the present invention can be used to provide a method for purifying polysilane compounds, which can further significantly reduce the content of metal components by subjecting materials that have already been purified by other methods to metal treatment again using the purification method of the present invention.

[0068] The present invention also relates to a method for producing a polysilane compound solution with reduced metal impurities. Specifically, this method includes a step of circulating the material solution to be purified, in which the polysilane compound to be purified is dissolved in the compound having at least one amide group skeleton, in a system connected by piping to a column packed with the ion exchange resin or chelating resin, and adsorbing and removing metal ions or colloidal substances of those metals in the material solution to obtain a purified material solution with reduced impurities. A part of the flow path connecting the tank and the column by piping is provided with an outlet for the purified material solution containing the purified material, which can be opened and closed with a valve, allowing the purified material solution to be withdrawn from the flow path connected by piping. A pump can also be installed in part of the piping, and the material solution to be purified can be circulated through the pump. The circulation of the material solution to be purified is preferably carried out in a closed system to prevent contamination with impurities from outside.

[0069] In the present invention, the liquid in which the polysilane compound to be purified is dissolved with the at least one compound having an amide group skeleton can be a pre-purified liquid (also referred to as a pre-treatment liquid). By using the pre-treatment liquid as the material solution to be purified (the composition solution before purification), a material solution (the composition solution after purification) in which impurities have been highly reduced can be obtained more efficiently.

[0070] The material solution with reduced impurities can be removed to obtain a material with reduced impurities, or the material solution with reduced impurities can be used as a composition solution containing the material as is.

[0071] When a pretreatment liquid is used, the purification of the purified liquid can be carried out in advance in a closed system for purifying the solution of the material to be purified (method 1), or in advance in a closed system separate from the above-mentioned closed system and then piped to the closed system for purifying the solution of the material to be purified (method 2). The method (1) is a method in which liquid purification and the material solution to be purified are carried out in the same apparatus, in which the material is charged after the liquid purification is carried out, and the material solution to be purified is prepared, and then the material solution to be purified is purified again in the same apparatus. The method (2) is a method in which the purification of the liquid and the solution of the material to be purified are carried out in separate equipment. After the purification of the liquid is carried out in a separate purification system, the liquid is temporarily stored in a tank or is directly sent via piping to the purification system in which the solution of the material to be purified is purified.

[0072] The concentration of the polysilane compound in the material solution to be purified, obtained by dissolving the polysilane compound in the compound having at least one amide group skeleton, is 3% by mass to 50% by mass, preferably 5% by mass to 30% by mass, and more preferably 5% by mass to 15% by mass.

[0073] In the present invention, the present technique can be combined with metal removal methods such as acid washing, washing with a CuCl2 aqueous solution, separation washing, reprecipitation purification, and metal removal filters. [Example]

[0074] The abbreviations for the solvents used in the examples are as follows: NEP: N-ethyl-2-pyrrolidone DMIB: N,N-dimethylisobutylamine DMF: N,N-dimethylformamide PGMEA: Propylene glycol monomethyl ether acetate CPME: Cyclopentyl methyl ether

[0075] [Example 1] Polysilane (OGSOL SI-20-10, 5.0 g) manufactured by Osaka Gas Chemicals Co., Ltd. was added to a 100 mL polyethylene bottle and dissolved with 45.1 g of NEP to prepare 50.1 g of a 10% by mass NEP solution. This prepared solution was used as the solution to be purified. 10.0 g of chelating resin CRB03 (trade name) manufactured by Mitsubishi Chemical Corporation (20% by mass of the prepared solution) was added to the prepared solution to be purified and stirred for 24 hours at room temperature using a mixing rotor. The CRB03 was then filtered off, yielding 45.6 g of purified solution. The molecular weight of the purified solution was measured by GPC, and found to be Mw = 1,442. The change from before to after the metal removal treatment was less than 10%, confirming that the treatment was successful without any denaturation. Furthermore, the amount of remaining metal was measured using inductively coupled plasma mass spectrometry (ICP-MS, Agilent Technologies). 7500). Metal removal ability was evaluated as good when the Mg, Cu, and Zn contaminants in the polysilane synthesis process were reduced to 2.0 ppm or less each.

[0076] GPC evaluation conditions The weight-average molecular weight, number-average molecular weight, and dispersity of the branched polysilane were measured using a GPC apparatus (EcoSEC, HLC-8420GPC, manufactured by Tosoh Corporation) and GPC columns (TSKgel SuperMultiporeHZ-N, TSKgel SuperMultiporeHZ-H, manufactured by Tosoh Corporation) at a column temperature of 40°C, using tetrahydrofuran as an eluent (elution solvent) at a flow rate (flow rate) of 0.35 mL / min, and using polystyrene (manufactured by Sigma-Aldrich) as a standard sample.

[0077] [Example 2] OGSOL SI-20-10 (5.0 g) was diluted with 45.2 g of DMIB to prepare 50.2 g of a 10% by mass DMIB solution, which was used as the solution to be purified. To this 50.2 g solution to be purified, 10.2 g of CRB03 (20% by mass relative to the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mixer rotor. The CRB03 was then filtered off, yielding 44.3 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 1.

[0078] [Example 3] OGSOL SI-20-10 (5.0 g) was diluted with 45.1 g of DMF to prepare 50.1 g of a 10% by mass DMF solution, which was used as the solution to be purified. The 50.1 g of the prepared solution to be purified was mixed with ORLITE, a strong acid cation exchange resin manufactured by Organo Corporation. TM 10.5 g of DS-4 (20% by mass of the solution to be purified) and ORLITE strong basic anion exchange resin (manufactured by Organo Corporation) TM 10.3 g of DS-2 (20% by mass of the solution to be purified) was added and mixed. The mixture was stirred at room temperature for 24 hours using a rotor. DS-4 and DS-2 were then separated by filtration to obtain 45.6 g of a purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 1.

[0079] [Example 4] Polysilane (OGSOL SI-20-14, 5.0 g) manufactured by Osaka Gas Chemicals Co., Ltd. was diluted with 45.0 g of NEP to prepare 50.0 g of a 10% by mass NEP solution, which served as the solution to be purified. To this 50.0 g solution to be purified, 10.2 g of CRB03 (20% by mass of the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mix rotor. The CRB03 was then filtered off, yielding 45.7 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 2.

[0080] [Example 5] OGSOL SI-20-14 (5.0 g) was diluted with 45.2 g of NEP to prepare 50.2 g of a 10% by mass NEP solution, which served as the solution to be purified. To this 50.2 g solution to be purified, 10.2 g of DS-4 (20% by mass relative to the solution to be purified) and 10.1 g of DS-2 (20% by mass relative to the solution to be purified) were added, and the mixture was stirred at room temperature for 24 hours using a mixer rotor. DS-4 and DS-2 were then filtered off, yielding 44.8 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 2.

[0081] [Example 6] Polysilane (OGSOL SI-10-20, 5.0 g) manufactured by Osaka Gas Chemicals Co., Ltd. was diluted with 45.1 g of NEP to prepare 50.1 g of a 10% by mass NEP solution, which was used as the solution to be purified. To this 50.1 g solution to be purified, 10.0 g of CRB03 (20% by mass of the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mix rotor. The CRB03 was then filtered off, yielding 45.3 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 4.

[0082] GPC evaluation conditions The weight-average molecular weight, number-average molecular weight, and dispersity of the linear polysilane were measured using a GPC apparatus (EcoSEC, HLC-8420GPC, manufactured by Tosoh Corporation) and GPC columns (TSKgel SuperMultiporeHZ-N, TSKgel SuperMultiporeHZ-H, manufactured by Tosoh Corporation) at a column temperature of 40°C, using tetrahydrofuran as an eluent (elution solvent), and a flow rate (flow rate) of 0.35 mL / min, using polystyrene (manufactured by Sigma-Aldrich) as a standard sample.

[0083] [Example 7] OGSOL SI-10-20 (5.0 g) was diluted with 45.0 g of DMIB to prepare 50.0 g of a 10% by mass DMIB solution. 10.1 g of CRB03 (20% by mass of the solution) was added to the 50.0 g of prepared solution, and the mixture was stirred at room temperature for 24 hours using a mixer rotor. The CRB03 was then filtered off, yielding 45.1 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 4.

[0084] [Example 8] OGSOL SI-10-20 (5.0 g) was diluted with 45.0 g of NEP to prepare 50.0 g of a 10% by mass NEP solution. To this 50.0 g solution, 10.0 g of DS-4 (20% by mass relative to the solution) and 10.0 g of DS-2 (20% by mass relative to the solution) were added and stirred at room temperature for 24 hours using a mixer rotor. DS-4 and DS-2 were then filtered off, yielding 44.8 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 4.

[0085] [Example 9] OGSOL SI-10-20 (5.0 g) was diluted with 45.2 g of NEP to prepare 50.2 g of a 10% by mass NEP solution, which was used as the solution to be purified. To this 50.2 g solution to be purified, 10.1 g of chelating resin XMS-5418 (trade name) manufactured by Muromachi Chemical Co., Ltd. (20% by mass relative to the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mix rotor. The XMS-5418 was then filtered off, yielding 45.8 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 4.

[0086] [Comparative Example 1] OGSOL SI-20-10 (5.1 g) was diluted with 45.2 g of PGMEA to prepare 50.3 g of a 10% by mass PGMEA solution, which was used as the solution to be purified. To this 50.3 g solution to be purified, 10.2 g of CRB03 (20% by mass of the solution to be purified) was added and stirred at room temperature for 24 hours using a mixer rotor. The CRB03 was then filtered off, yielding 44.3 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 1.

[0087] Comparative Example 2 OGSOL SI-20-10 (5.0 g) was diluted with 45.1 g of CPME to prepare 50.1 g of a 10% by mass CPME solution, which was used as the solution to be purified. To this 50.1 g solution to be purified, 10.1 g of CRB03 (20% by mass of the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mixer rotor. The CRB03 was then filtered off, yielding 42.6 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 1.

[0088] Comparative Example 3 OGSOL SI-20-10 (5.0 g) was diluted with 45.0 g of PGMEA to prepare 50.0 g of a 10% by weight PGMEA solution. To this 50.0 g solution, 10.2 g of DS-4 (20% by weight of the solution) and 10.2 g of DS-2 (20% by weight of the solution) were added and stirred at room temperature for 24 hours using a mixer rotor. DS-4 and DS-2 were then filtered off, yielding 44.8 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 1.

[0089] Comparative Example 4 OGSOL SI-20-14 (5.0 g) was diluted with 45.1 g of PGMEA to prepare 50.1 g of a 10% by mass PGMEA solution, which was used as the solution to be purified. To this 50.1 g solution to be purified, 10.1 g of CRB03 (20% by mass relative to the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mixer rotor. The CRB03 was then filtered off, yielding 40.9 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 2.

[0090] Comparative Example 5 OGSOL SI-20-14 (5.1 g) was diluted with 45.1 g of CPME to prepare 50.2 g of a 10% by mass CPME solution, which was used as the solution to be purified. To this 50.2 g solution to be purified, 10.1 g of CRB03 (20% by mass relative to the solution to be purified) was added, and the mixture was stirred at room temperature for 24 hours using a mixer rotor. The CRB03 was then filtered off, yielding 42.6 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 2.

[0091] Comparative Example 6 OGSOL SI-20-14 (5.0 g) was diluted with 45.1 g of PGMEA to prepare 50.1 g of a 10% by mass PGMEA solution, which was used as the solution to be purified. 10.1 g of DS-4 (20% by mass relative to the solution to be purified) and 10.3 g of DS-2 (20% by mass relative to the solution to be purified) were added to the 50.1 g of the prepared solution to be purified, and the mixture was stirred in a mixer at room temperature for 24 hours. DS-4 and DS-2 were then filtered off, and the purified solution was The molecular weight and residual metal content of the purified solution are shown in Table 2.

[0092] Comparative Example 7 OGSOL SI-20-14 (5.0 g) was diluted with 45.0 g of CPME to prepare 50.0 g of a 10% by mass CPME solution. To this 50.0 g solution, 10.2 g of DS-4 (20% by mass relative to the solution) and 10.0 g of DS-2 (20% by mass relative to the solution) were added and stirred at room temperature for 24 hours using a mixer rotor. DS-4 and DS-2 were then filtered off, yielding 47.1 g of purified solution. The molecular weight and residual metal content of the purified solution are shown in Table 2.

[0093] Table 1 shows the molecular weight and residual metal content of polysilane compound SI-20-10 before and after purification. Table 2 shows the molecular weight and residual metal content of polysilane compound SI-20-14 before and after purification. Table 3 shows the molecular weight and residual metal content of polysilane compound SI-10-20 before and after purification. The values ​​of residual metal content listed are converted to 100% by mass of the polysilane compound. The target residual metal content was set to 2.0 ppm or less, based on the example in Japanese Patent Publication No. 2011-162792, which states that "polysilane compounds containing metals such as zinc (Zn) were removed to 2.0 ppm by washing with an aqueous solution containing a metal with low ionization tendency." Furthermore, the target metals for branched-chain polysilane compounds were Mg, Cu, and Zn, which are contaminants during the synthesis process. On the other hand, the target metals for linear-chain polysilane compounds were Cr, Fe, and Zn, which are contaminants during the synthesis process.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] As shown in Tables 1 to 3, in the metal removal methods using amide solvents in Examples 1 to 9, metals could be removed to below the target level without a significant change in the molecular weight of the polysilane compound to be purified, whereas in the metal removal methods using non-amide solvents in Comparative Examples 1 to 7, metal removal was poor and not practical.

Claims

1. A method for purifying a polysilane compound, comprising at least a preparation step of diluting a polysilane compound containing metal impurities with at least one compound having an amide group skeleton, and a metal removal step of removing the metal impurities from a system by subjecting the diluted polysilane compound to a metal removal treatment, The method for purifying a polysilane compound, wherein the metal removal treatment is a treatment for removing metal impurities using an ion exchange resin or a chelating resin.

2. 2. The method for purifying a polysilane compound according to claim 1, wherein the polysilane compound is a compound having at least one structural unit selected from structural units represented by the following formulas (1) to (3), and has a weight-average molecular weight of 50 to 30,000: 【Chemistry 1】 (In the formula, R is a hydrogen atom, a hydroxy group, a silyl group, or an organic group, and n is an integer of 1 or more.)

3. 3. The method for purifying a polysilane compound according to claim 2, wherein the silyl group is a silanyl group having 1 to 6 silicon atoms, and the organic group is an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 10 carbon atoms.

4. 4. The method for purifying a polysilane compound according to claim 1, wherein the compound having an amide group skeleton is a compound having a structure represented by the following formula (4): 【Chemistry 2】 (In the formula, R １ , R ２ , and R ３ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an ether group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, or R １ and R ２ may be bonded to form a ring, in which case R １ may represent an amino group which may be substituted with an alkyl group having 1 to 10 carbon atoms.

5. The R １ , R ２ , and R ３ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an ether group having 1 to 5 carbon atoms, or R １ and R ２ may be bonded to form a ring, in which case R １ 5. The method for purifying a polysilane compound according to claim 4, wherein may represent an amino group which may be substituted with an alkyl group having 1 to 5 carbon atoms.

6. 5. The method for purifying a polysilane compound according to claim 4, wherein the compound having an amide group skeleton is N-methylpyrrolidone, N-ethylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropanamide, N,N-dimethylformamide, N,N-dimethylacetamide, or N,N-dimethylisobutyramide.

7. 7. The method for purifying a polysilane compound according to claim 1, wherein the ion exchange resin is a mixture of a cation exchange resin and an anion exchange resin.

8. 8. The method for purifying a polysilane compound according to claim 7, wherein the cation exchange resin is a resin having a structure represented by the following formula (6), and the anion exchange resin is a resin having a structure represented by the following formula (7) or (8): 【Transformation 3】

9. The method for purifying a polysilane compound according to any one of claims 1 to 6, wherein the chelating resin is a polymeric substance having a unit structure represented by the following formula (A-1) or a polymeric substance having at least one unit structure selected from the group consisting of unit structures represented by the following formulas (B-1) to (B-4): 【Chemistry 4】 (wherein n represents an integer of 1 to 10, A １ is a unit structure constituting silica, a silica component-containing substance, polystyrene, or crosslinked porous polystyrene as a carrier, and A ２ is a single bond or A １ and a functional group, and the linking group represents an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, a nitrogen atom, or a sulfur atom. 【Transformation 5】 (In the formula, B １ is a unit structure constituting silica, a silica component-containing substance, polystyrene, or crosslinked porous polystyrene as a carrier, and B ２ is a single bond or B １ and the thiourea group or thiouronium group, and the linking group is an alkylene group having 1 to 10 carbon atoms which may contain an oxygen atom, a nitrogen atom, or a sulfur atom; B ３ is a phenyl group which may be substituted with a hydroxyl group and / or an alkyl group having 1 to 3 carbon atoms.

10. 10. The method for purifying a polysilane compound according to claim 1, wherein the metal impurities are at least one selected from the group consisting of Mg, Cu, Zn, Cr, and Fe.

11. 11. The method for purifying a polysilane compound according to claim 1, wherein the amount of the metal impurities is reduced to 2 ppm or less in terms of 100% by mass of the polysilane compound.

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