Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-11-17
2002-03-05
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S031000, C556S451000, C556S452000
Reexamination Certificate
active
06353074
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a hydrogen-silsesquioxane resin by the hydrolytic condensation of trichlorosilane (HSiCl
3
). This invention also relates to a method for manufacturing a hydrogen-silsesquioxane resin which allows more or less complete re-utilization of the solvent, sulfuric acid and surfactants used, without any loss of these compounds.
BACKGROUND OF THE INVENTION
Hydrogen-silsesquioxane resins are useful precursor substances for silica-containing ceramic coatings. For example, U.S. Pat. No. 4,756,977 discloses a method for forming a coating in which a hydrogen-silsesquioxane resin is diluted with a solvent, applied to a substrate, and then forming a ceramic or ceramic-like coating by heating.
When trichlorosilane is subjected to hydrolytic condensation caused by direct contact with water, the reaction occurs abruptly, and the resin that is produced gels. Accordingly, various methods for manufacturing hydrogen-silsesquioxane resins (which are hydrolytic condensation products of trichlorosilane) while preventing such gelation have been proposed in the past.
For example, a method in which a hydrogen-silsesquioxane resin is manufactured by subjecting a solution of trichlorosilane dissolved in a hydrocarbon solvent to hydrolytic condensation while mixing said solution in a two-phase reaction medium consisting of concentrated sulfuric acid and an aromatic hydrocarbon is disclosed in Japanese Patent Application Kokoku No. Sho 47-31838. In that patent application, the aforementioned concentrated sulfuric acid and aromatic hydrocarbon react to produce an arylsulfonic acid hydrate, and the water of hydration in this hydrate contributes to the hydrolytic condensation of the aforementioned trichlorosilane. Then, a hydrogen-silsesquioxane resin produced by this hydrolytic condensation is obtained from the organic phase, and a mixture of concentrated sulfuric acid, arylsulfonic acid hydrate and non-hydrated arylsulfonic acid are obtained from the concentrated sulfuric acid phase. The non-hydrated arylsulfonic acid is obtained in large quantities. In experiments performed by the present inventors, it was found that when water is added to the concentrated sulfuric acid phase in an attempt to recover and reuse the arylsulfonic acid contained in said phase, precipitation occurs (for unknown reasons), so that the arylsulfonic acid cannot be reused. For this reason, large quantities of organic solvent and sulfuric acid are lost.
A method in which a hydrogen-silsesquioxane resin is formed by adding a solution containing trichlorosilane to a hydrolysis medium containing an arylsulfonic acid hydrate while this hydrolysis medium is agitated in described in Japanese Patent Application Kokai No. Hei 6-41518. That patent application describes a method in which concentrated sulfuric acid is added to toluene or benzene as a method for manufacturing the above mentioned hydrolysis medium containing an arylsulfonic acid hydrate. Furthermore, it is indicated that the water of hydration contained in the arylsulfonic acid hydrate thus formed is utilized in the hydrolytic condensation of the trichlorosilane. No mention is made concerning the re-utilization of the non-hydrated arylsulfonic acid that is produced, or concerning the recovery in any way of the organic solvent or sulfuric acid in that reference.
The present invention relates to a method for manufacturing a hydrogen-silsesquioxane resin by the hydrolytic condensation of trichlorosilane (HSiCl
3
). An object of the present invention is to provide a method for manufacturing a hydrogen-silsesquioxane resin which allows more or less complete re-utilization of the solvent, sulfuric acid and surfactants used, essentially without loss of these compounds.
SUMMARY OF THE INVENTION
The present invention pertains to a method for the manufacture of a hydrogen-silsesquioxane resin by the hydrolytic condensation of trichlorosilane (HSiCl
3
) in a two-phase system consisting of (I) aqueous phase: an aqueous solution in which sulfuric acid and an organic sulfonic acid selected from aromatic sulfonic acids or aliphatic sulfonic acids are dissolved, with the sulfuric acid comprising 80 to 96 wt % of the total amount of sulfuric acid and water present in the aqueous phase (in cases where the organic sulfonic acid is a hydrate, this includes the water of hydration contained in said hydrate); and
(II) organic phase: a solution formed by dissolving the organic sulfonic acid at the rate of 0.008 moles/liter or greater in a halogenated hydrocarbon solvent which is capable of dissolving the trichlorosilane, and which has no substantial reactivity with respect to sulfuric acid.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a method for manufacturing a hydrogen-silsesquioxane resin in which trichlorosilane (HSiCl
3
) is subjected to a hydrolytic condensation in a two-phase system consisting of an aqueous phase (I) and an organic phase (II) shown below:
(I) aqueous phase: an aqueous solution in which sulfuric acid and an organic sulfonic acid selected from aromatic sulfonic acids or aliphatic sulfonic acids are dissolved, with the sulfuric acid comprising 80 to 96 wt % of the total amount of sulfuric acid and water present in the aqueous phase (in cases where the organic sulfonic acid is a hydrate, this includes the water of hydration contained in said hydrate); and
(II) organic phase: a solution formed by dissolving the organic sulfonic acid at the rate of 0.008 moles/liter or greater in a halogenated hydrocarbon solvent which is capable of dissolving the trichlorosilane, and which has no substantial reactivity with respect to sulfuric acid; here, the weight ratio of the organic sulfonic acid (excluding the weight of the water of hydration contained in the compound in cases where said organic sulfonic acid is a hydrate) relative to the total weight of the sulfuric acid, organic sulfonic acid and (if necessary) water that are added in order to form the two phases is 5 wt % or greater.
As described above, the aqueous phase in the present invention comprises water, a large quantity of sulfuric acid and an organic sulfonic acid comprising the major portion of the aqueous phase. It is necessary that the concentration of sulfuric acid in this aqueous phase be in the range of 80 wt % to 96 wt % of the combined weight of water and sulfuric acid present in the aqueous phase. Described herein, the term “water present in the aqueous phase” naturally also includes water contained in the aqueous solution of sulfuric acid that is added to the aqueous phase, and water separated from organic sulfonic acids having water of hydration in the aqueous phase.
In cases where the concentration of sulfuric acid is outside the above mentioned range, the yield drops noticeably even if the other conditions of the present invention are satisfied.
Furthermore, the sulfuric acid that is used to form the aqueous phase may be an aqueous solution of sulfuric acid, 100% sulfuric acid or fuming sulfuric acid. The sulfuric acid used for the purpose of forming the aqueous phase is ordinarily added in the form of an aqueous solution of sulfuric acid. In cases where the amount of water that may be contained in the sulfuric acid and the amount of water of hydration that may be possessed by the organic sulfonic acid are insufficient for the hydrolytic condensation of the trichlorosilane, water must be separately added.
A solvent which can dissolve both trichlorosilane and a surfactant, and which has no substantial reactivity with respect to sulfuric acid, is selected as the halogenated hydrocarbon solvent used in the organic phase in the present invention. Here, the term “no substantial reactivity” means that no reaction occurs when the halogenated hydrocarbon solvent and the sulfuric acid are used in the manufacturing method of the present invention, or that the reaction rate is extremely slow so that the solvent is consumed by the reaction at a level that causes no practical problems.
Examples of such halogenated hydrocarbon solvents
Carpenter, II Leslie Earl
Michinio Tetsuyuki
Dawson Robert
Dow Corning Corporation
Robertson Jeffrey B.
Severance Sharon K.
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