JPS61127732A - Molecular weight fractionation of ladder-type silicone resin - Google Patents

Abstract

PURPOSE:To carry out the titled fractionation in high reproducibility, by dissolving a silylated silsesquioxane polymer in a solvent having the maximum average molecular weight to be fractionated as the limit of soluble molecular weight, and precipitating the polymer from the solution by the addition of a solvent having the minimum average molecular weight to be fractionated as the limit of soluble molecular weight. CONSTITUTION:For example, a component having a molecular weight of 1-5X10<4> is fractionated from a silylated silsesquioxane polymer (e.g. polymethyl silsesquioxane), by dissolving the component having a weight-average molecular weight (Mw) of <=5X10<4> in a solvent having the maximum average molecular weight to be fractionated as the limit of soluble molecular weight (e.g. isopropanol), removing the insoluble component, adding a solvent having the minimum average molecular weight to be fractionated as the limit of soluble molecular weight (e.g. methanol) to effect the precipitation of the component having Mw of >1X10<4>, and recovering the precipitate. EFFECT:The obtained resin has excellent sharpness and sensitivity when used as an electron beam resist.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for fractionating a silylated silsesquioxane polymer having a ladder structure (also known as a ladder silicone resin) into a polymer having a specific molecular weight distribution.

The inventors have discovered that a silylated silsesquioxane polymer exhibits excellent resolution and sensitivity as an electron beam resist, and have proposed its use.

Here, the manufacturing method of silsesquioxane-based polymers such as polymethylsilsesquioxane, polyphenylsilsesquioxane, and polyphenylmethylsilsesquioxane is as follows: For example, methyltrichlorosilane, methyl Trimethoxysilane and the like are hydrolyzed at low temperatures to form a trifunctional monomer, which is then subjected to a polycondensation reaction to form a polymer, resulting in a very wide molecular weight distribution.

Therefore, if such a silsesquioxane polymer is silylated and then used as an electron beam resist as it is, the resist will have poor resolution due to the difference in solubility in a solvent depending on the molecular weight.

Therefore, it is necessary to separate and use resins within a specific molecular weight range.

The present invention relates to a new method for fractionating the molecular weight distribution of silylated silsesquioxane polymers.

[Conventional technology]

Conventionally, a method for separating silylated silsesquioxane polymers into specific ranges from their molecular weight distribution is to dissolve them in a solvent such as 4-methyl-2-pentanone and then add a non-solvent such as acetonidrile. Separation was carried out using the phenomenon of precipitation.

However, when using this method, there is a problem in that it is not possible to reproducibly separate substances with the desired molecular weight composition because the amount of non-solvent added and the temperature have a large effect.Therefore, there is a need for a method that can perform preparative separation with good reproducibility. It had been.

[Problem that the invention seeks to solve]

As mentioned above, the problem is that no good method has been found for separating only a specific molecular weight distribution region from silylated silsesquioxane polyesters having a wide molecular weight distribution.

[Means for solving problems]

The above problem can be solved by first determining the relationship between the solvent and the maximum average molecular weight in which it can be dissolved in various solvents that dissolve the silylated silsesquioxane polymer, and then determining the maximum average molecular weight to be fractionated as the solubility limit. A resin solution with a molecular weight below the required average molecular weight is prepared using a solvent, and then a solvent whose solubility limit is the minimum average molecular weight to be fractionated is added to the solution to precipitate and separate the resins within the fractionation range. This problem can be solved by using a molecular weight fractionation method for ladder-type silicone resin, which is characterized by the following.

[Effect]

The solubility of silsesquioxane-based polymers in solvents depends on the molecular weight of this polymer and the number of hydroxy groups (OH groups) that this polymer has, but the inventor discovered that the 08P! As a result of investigating the solubility in solvents when E was silylated to remove the solubility factor due to the OR group, it was found that the solubility clearly changes depending on the molecular weight.

That is, there are solvents that act weakly on solutes and solvents that act strongly on solutes, but it has been found that the maximum average molecular weight of the silsesquioxane-based polymer in which the solute is soluble differs clearly depending on the solvent.

The table shows the solubility limits for each solvent in order of strength of the solvent.

In other words, when it is desired to separate components with a molecular weight of 1 to 5 XIO' from a silylated silsesquioxane polymer, the present invention uses a resin with a wide molecular weight distribution and extracts components with an M- of up to 5X10' using lysopropanol. After that, when methanol is added, components in which M- exceeds IXIO' precipitate, and are collected to perform fractionation with good reproducibility.

〔Example〕

Hereinafter, a method for producing silylated polymethylsilsesquioxane as a ladder-type silicone resin and a method for separating a specific molecular weight component from among the resin components having a wide molecular weight distribution obtained by this method will be described with reference to Examples.

Synthesis example of polymethylsilsesquioxane:.

250 g of 4-methyl-2-pentanone and 3 triethylamine
1.2 g was placed in a 12 round bottom flask and cooled to -20°C in a dry ice-ethanol bath.

Next, while stirring, 45 g of methyltrichlorosilane and then 54 g of deionized water were added dropwise.

After the dropwise addition was completed, the mixture was gradually raised to room temperature, and then
The reaction was allowed to proceed for 4 hours at a temperature of 5°C.

At this time, nitrogen gas (N2) was bubbled to remove chlorine gas (C1z) in the system to the outside of the system.

After the reaction was completed, the organic layer was washed 5 times with deionized water (No. 11) and separated.

Next, as a silylation method, 50 g of trimethylchlorosilane was added to the organic layer thus obtained, and 50 g of dehydrated pyridine was added dropwise while stirring.

This reaction solution was washed 5 times with 11 deionized water, and the organic layer was separated.

500 cc of acetonitrile was added thereto, and the resulting precipitate was suction filtered and dried to obtain silylated polymethylsilsesquioxane.

As a result of examining this resin by GPC analysis, it was found that the weight average molecule f
i (Mw) is 5xio', and the degree of dispersion (Mw/Mn)
was 6.5.

Example 1: 10 g of silylated polymethylsilsesquioxane synthesized in this manner was dissolved in 200 cc of isopropanol, heated at 60°C for 20 minutes, and then left at 20°C for 24 hours. did.

Next, after removing the undissolved matter by the decanting method, the solution was
The mixture was poured into 0 cc of acetonitrile, and the precipitate was suction filtered and dried.

h in this case is 5X10' and the degree of dispersion is 1.8
Met.

Example 2: The silylated polymethylsilsesquioxane IQg synthesized by the above method was dissolved in 200 cc of cyclohexanone, heated at 60°C for 20 minutes, and then heated at 20°C for 24 minutes.
Let it stand for a while.

Next, after removing insoluble components by a decanting method, tl of isopropanol was added, and the resulting precipitate was filtered with suction and dried.

The resin thus obtained had an Mw of 13×10′ and a dispersity of 2.3.

〔Effect of the invention〕

As described above, the present invention utilizes the fact that silylated silsesquioxane has distinct solubility characteristics in solvents, and uses two strong and weak solvents to separate resins with a specific molecular weight distribution. By carrying out the invention, fractionation with good reproducibility becomes possible.

Claims (1)

[Claims] For various solvents that dissolve silylated silsesquioxane polymers, first determine the relationship between the solvent and the maximum average molecular weight in which it can be dissolved, and first use a solvent whose solubility limit is the maximum average molecular weight to be fractionated. A resin solution having a required average molecular weight or less is prepared, and then a solvent whose solubility limit is the minimum average molecular weight to be fractionated is added to the solution to precipitate and separate the resins in the fractionation range. Molecular weight fractionation method for ladder-type silicone resin.