JP2003026808A - Method for producing organosilicon polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen uses of an organosilicon polymer material in which metal impurities are reduced to such a level that the organosilicon polymer material can be applied to an electronic part without impairing essential properties of the organosilicon polymer including a polysilane. SOLUTION: In this method for organosilicon polymer purification, removing metal impurities, the organosilicon polymer or a solution of the organosilicon polymer in a nonpolar solvent is stirred in the presence of a water-soluble compound having complex formation ability of an equivalent or more based on the metal impurities at a room temperature-150 deg.C for >=5 minutes and cleaned with pure water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying an organosilicon polymer by reducing metal impurities in the organosilicon polymer such as polysilane to a level usable for electronic materials.

[0002]

2. Description of the Related Art Conventionally, polysilane materials have been attracting attention for their unique chemical, optical, and electronic properties, such as conductive materials, photoconductive materials, and
It is expected as a non-linear optical material. However, the Si-Si bond, which is the basic skeleton of organosilicon-based polymers such as polysilane, is a condition under which a large amount of ionic by-products, such as the wurtz reaction of chlorosilanes with alkali metals such as metallic sodium, is generated. In many cases, they are synthesized, and the removal of these impurities is incomplete, which limits their application to electronic materials.

In this case, conventional purification methods include a method of repeatedly extracting an organic silicon-based polymer solution with an acidic aqueous solution (Japanese Patent Laid-Open No. 11-12362) or a method of washing the organic silicon-based polymer solution with hydrochloric acid water. Methods such as washing with ultrapure water (Japanese Patent Laid-Open No. 11-199675) have been known. However, while these methods can easily remove metal impurities, there is a risk of decomposition of the organosilicon polymer and an increase in the content of acidic components such as chlorine in the organosilicon polymer.

Therefore, according to the present invention, the metal impurities in the organosilicon polymer can be reduced to a level usable for electronic materials by a relatively simple operation without impairing the inherent properties of the organosilicon polymer. It is an object of the present invention to provide a method for purifying an organosilicon polymer that can be used.

[0005]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that it contains a metal impurity such as polysilane synthesized by the Wurtz reaction, which is easily ionized. As a method for purifying an organosilicon-based polymer, when a gel-like by-product is present in advance, it is preferable to remove the by-product and then dissolve the polymer in a non-polar solvent such as toluene if necessary to prepare a water-soluble complex. A compound having a forming ability (complexing agent) or a non-aqueous solution thereof is added, and the mixture is stirred at room temperature to 150 ° C for 5 minutes or more, and then preferably has an electric resistance of not less than half of the organosilicon polymer solution. 10 MΩ / c
It was found that the removal of metal impurities can be efficiently achieved by repeating washing with pure water of m or more twice or more, and the present invention has been accomplished.

That is, the present invention relates to a method for removing metal impurities in an organosilicon polymer, wherein a solution of the organosilicon polymer or a non-polar solvent thereof is water-soluble in an amount equal to or more than the metal impurities and has a complexing ability. A method for purifying an organosilicon polymer, which comprises stirring at room temperature to 150 ° C. for 5 minutes or more in the coexistence of a certain compound, and further washing with pure water.

According to the present invention, it is possible to reduce ionic impurities to a level at which it can be used for electronic material applications, etc., compared with organosilicon polymers, and particularly conductive materials,
Efficiently suppresses the mixing of acidic substances and polymer decomposition of ionic impurities and metal impurities that are obstacles to taking advantage of the properties of organosilicon polymers such as polysilane that are useful as photoconductive substances and nonlinear optical substances. Can be removed.

The present invention will be described in more detail below.

The purification method according to the present invention includes polysilanes, particularly polysilanes produced by the Wurtz reaction, polycarbosilanes produced by the Wurtz reaction, as well as organic silicon-based polymers produced by the ring-opening polymerization method or the anion polymerization method. It is applicable to any polymer containing a polar metallic impurity. These polymers may be linear or branched polymers as long as they are soluble in an organic solvent. According to the invention, the main chain Si-
It is also applicable to a polymer containing a Si bond or a side chain group such as a phenyl group or hydrogen group on silicon, which may be decomposed by a strong acid. The degree of polymerization of the above-mentioned polymer is not particularly limited, but it is preferable that the number of Si-chains is 2 or more, and the weight average molecular weight is 500 to 500,000.
Although the thing of about 0 can be used, a polymerization degree and a molecular weight are not limited to this.

In the present invention, the liquid organosilicon polymer is used as it is, preferably dissolved in a nonpolar organic solvent and diluted before use, and the solid one is dissolved in a nonpolar organic solvent before use. To serve. Any organic solvent may be used as long as it can dissolve the organosilicon polymer, and examples thereof include toluene and xylene. Although the concentration of the organosilicon polymer in the organic solvent is appropriately selected, it is 3 to 50% by weight, preferably 5 to 30% by weight, more preferably 10 to 20% by weight.

In the present invention, first, a compound (complexing agent) which is water-soluble and has a complex-forming ability in the above-mentioned organosilicon polymer solution.
Is added, and the mixture is stirred at room temperature or under heating conditions.Metal impurities that are easily ionized in a homogeneous reaction are insolubilized or made water-soluble as a metal salt or complex salt, and then easily removed by washing with pure water. Is what you do. As the complexing agent used in the present invention, acetic acid, in addition to monocarboxylic acids such as propionic acid, oxalic acid,
Polycarboxylic acids such as malonic acid, succinic acid, malic acid and citric acid, amino acids such as glycine and alanine, E
A chelating agent such as DTA (ethylenediaminetetraacetic acid) or acac (acetylacetone), an inclusion lattice compound such as cyclodextrin, or the like can also be selected. These water-soluble and complex-forming compounds (complexing agents) are selected in consideration of solubility in organic solvents, water-solubility of metal salts, pKa, ability to form complexes with metals, and the like, alone or in combination. Although they can be used, polycarboxylic acids are preferable, and citric acid is effective for removing iron and the like.

The complexing agent used in the present invention generally has a weak strength as an acid and a small action of decomposing the skeleton of the organosilicon polymer, but the treatment with a homogeneous system allows the metal and the metal ion to be efficiently treated. Can be captured. Further, in the case of the treatment using the same complex-forming agent, in the case of adding to the organic silicon-based polymer solution and heating, compared with the case of simply performing the washing operation with the complex-forming agent solution, metal impurities The removal effect is high.

The amount of the complexing agent used is not particularly limited, but is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the polymer solution. This complex-forming agent can be used as it is or as a non-aqueous solution such as alcohol. At this time, it is preferable that the reaction solution is uniform, but even if it is non-uniform, there is no particular problem. The reaction temperature is room temperature (20 ° C.) to 150 ° C., and the reaction can be performed at room temperature or by heating, but under a reflux condition where the movement of the organosilicon-based polymer molecule becomes larger when diluted or dissolved in an organic solvent. It is preferable to carry out. The reaction time is 5 minutes or longer, preferably 15 minutes to 3 hours, but is not particularly limited. Considering that this reaction is usually a weak acid reaction, a certain reaction time is required to reduce the metal content as compared with the hydrochloric acid washing method.

In the present invention, the subsequent washing with pure water is intended to dissolve and remove the metal salt formed by the reaction with the complex-forming agent, or to extract and remove it from the organic solvent containing the organosilicon polymer. It is a thing. As the pure water, it is preferable to use one having an electric resistance of 10 MΩ / cm or more, and as the cleaning method, a known method of liquid cleaning can be adopted. For example, a method using a separating funnel or a shaker is used. A method etc. can be adopted.
In addition, the amount of pure water used for one washing is 100% polymer solution.
30 to 300 parts by weight, especially 50 to 200 parts by weight
It can be part by weight.

The washing with tap water may be performed before the pure water washing, but the impurities contained in the tap water may be mixed, and the subsequent pure water washing is indispensable. The number of times of washing is preferably twice or more, more preferably three times or more.

[0016]

EFFECTS OF THE INVENTION According to the present invention, without impairing the original properties of organosilicon polymers such as polysilane,
The metal impurities can be removed to a level where it can be applied to electronic materials, and the applications of organosilicon polymer materials can be expanded.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following examples and comparative examples, but the examples do not limit the present invention.

[Examples 1 to 5] Weight average molecular weight 62,000
To 5 ml of a 10% toluene solution of poly (phenylmethylsilane) having a number average molecular weight of 17,000, 2.5 g of a complexing agent or 5 ml of a corresponding methanol solution was added, heated and refluxed for 2 hours. The mixture was stirred underneath. Transfer the solution to a separatory funnel and have an electric resistance of 10 MΩ /
The washing with 100 ml of pure water of cm or more was repeated 3 times. Methanol was reprecipitated from the washed solution to precipitate poly (phenylmethylsilane), which was then dried to obtain a purified product. By this operation, although each complexing agent showed specificity to the metal, the content of major metal impurities was reduced as shown in Table 1.

[Comparative Example] 50 m of a 10% toluene solution of the same poly (phenylmethylsilane) as that used in the Examples
l, washed twice with 50 ml of 20% oxalic acid solution, and then 100 m of pure water with an electric resistance of 10 MΩ / cm or more
The washing with 1 was repeated 3 times. Methanol was reprecipitated from the washed solution to precipitate poly (phenylmethylsilane), which was then dried to obtain a purified product. The results are shown in Table 1 together with Examples 1 to 5.

[0020]

[Table 1]

Claims (6)

[Claims] 1. A method for removing metal impurities in an organosilicon polymer, wherein a solution of the organosilicon polymer or a non-polar solvent thereof is present in a water-soluble amount equal to or more than the metal impurities and capable of forming a complex. Room temperature under ~ 150
A method for purifying an organosilicon polymer, which comprises stirring at a temperature of ° C for 5 minutes or more and further washing with pure water. 2. The purification method according to claim 1, wherein the organosilicon polymer is an organic solvent-soluble polysilane having a linear or branched structure. 3. The method according to claim 1, wherein the organosilicon-based polymer is polycarbosilane containing an organic solvent-soluble silicon-silicon bond having a linear or branched structure. 4. The purification method according to claim 1, wherein the organosilicon-based polymer is a polysiloxane containing a silicon-silicon bond soluble in an organic solvent and having a linear or branched structure. 5. The purification method according to claim 1, wherein the water-soluble compound having a complex-forming ability is an organic solvent-soluble polycarboxylic acid. 6. Pure water used for cleaning has an electric resistance of 10 MΩ.
/ Cm or more, the purification method according to any one of claims 1 to 5.