Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2001-09-04
2003-04-22
Vollano, Jean F. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
Reexamination Certificate
active
06552218
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to a process for producing a hydroxyalkyl (meth)acrylate by performing a reaction between (meth)acrylic acid and an alkylene oxide.
B. Background Art
In the case of producing a hydroxyalkyl (meth)acrylate by performing a reaction between (meth)acrylic acid and an alkylene oxide, the formation of a diester (alkyleneglycol di(meth)acrylate) as a by-product has so far been a problem. The diester has two unsaturated bonds within one molecule, and promotes the polymerization of an object, the hydroxyalkyl (meth)acrylate, and causes the trouble such as clogging of an apparatus. Furthermore, in the case of producing a (co)polymer from a raw material of the hydroxyalkyl (meth)acrylate containing the diester, turbidity arises in the resulting polymer, or the hydroxyalkyl (meth)acrylate containing the diester causes the occurrence of gelation at the time of polymerization. Furthermore, the vapor pressure of the diester is approximate to that of the hydroxyalkyl (meth)acrylate. Therefore, once the diester is formed, the separation thereof is extremely difficult. In addition, when an object, the hydroxyalkyl (meth)acrylate is distilled and purified, the diester is also formed by a disproportionation reaction thereof.
It is known that the diester is apt to form when a reaction liquid of (meth)acrylic acid and the alkylene oxide, or the resulting hydroxyalkyl (meth)acrylate is elevated to a high temperature (e.g. JP-A-133227/1976). Therefore, if a reaction temperature or a distillation temperature is low, the formation of the diester is controlled to some degree. However, when the reaction temperature is low, the period of reaction step time lengthens very much, and so that there is not only a possibility that the productivity falls, but also a possibility that part of a product polymerizes because of the long period of reaction step time or that other by-products increase. Accordingly, falling the reaction temperature or the distillation temperature is not a practical countermeasure.
A method of controlling the formation of the diester at the time of distillation by deactivating a specific catalyst used in the reaction is disclosed (e.g. JP-A-194321/1993). However, there is a disadvantage that the available catalyst is limited, or that the catalyst is not applicable to the formation of the diester at the time of the reaction, and the control effect thereof was insufficient.
SUMMARY OF THE INVENTION
A. Object of the Invention
An object of the present invention is to provide a process for producing a hydroxyalkyl (meth)acrylate which enables to control the formation of a diester sufficiently at the time of reaction and/or at the time of distillation.
B. Disclosure of the Invention
The present inventors diligently studied to achieve the above object. As a result, they have found that the above object could be solved completely by allowing a liquid with a specific relative dielectric constant to coexist at the time of a reaction between (meth)acrylic acid and an alkylene oxide and/or at the time of distillation of a hydroxyalkyl (meth)acrylate.
That is to say, a process for producing a hydroxyalkyl (meth)acrylate, which comprises the step of carrying out a reaction between (meth)acrylic acid and an alkylene oxide in the existence of a catalyst; with the process being characterized in that when the reaction between (meth)acrylic acid and the alkylene oxide is carried out, there coexists a liquid having a relative dielectric constant of not less than 20 at 25° C.
An another process for producing a hydroxyalkyl (meth)acrylate, which comprises the step of carrying out a reaction between (meth)acrylic acid and an alkylene oxide in the existence of a catalyst; with the process being characterized by further comprising the step of distilling the resultant hydroxyalkyl (meth)acrylate in the coexistence of a liquid having a relative dielectric constant of not less than 20 at 25° C.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
First, an outline of a process for producing a hydroxyalkyl (meth)acrylate which the characteristic production process of the present invention can favorably apply to is explained as follows.
First, a reaction between (meth)acrylic acid and an alkylene oxide is carried out in the existence of a catalyst. The reaction rate of this reaction does not reach 100% in many cases, and it is general that the unreacted (meth)acrylic acid or alkylene oxide or such remains in a reaction liquid at the time of the end of the reaction. Then, the above reaction liquid is introduced into the step of removing the unreacted raw materials and such from the reaction liquid. As the subsequent final step, purification such as distillation is performed to obtain an object, the hydroxyalkyl (meth)acrylate.
Hereinafter, the features of the production process of the present invention are explained below.
The alkylene oxide which can be used in the present invention are favorably an alkylene oxide having 2 to 6 carbon atoms, more favorably an alkylene oxide having 2 to 4 carbon atoms. Examples thereof include ethylene oxide, propylene oxide, and butylene oxide, more favorably ethylene oxide and propylene oxide. Incidentally, (meth)acrylic acid used in the present invention means acrylic acid or methacrylic acid.
When the present invention is carried out, the amount of raw materials as charged for the above reaction between the (meth)acrylic acid and the alkylene oxide is favorably in the range of not less than 1 mol of the alkylene oxide per 1 mol of the (meth)acrylic acid, more favorably in the range of 1.0 to 5.0 mol, still more favorably in the range of 1.0 to 3.0 mol, especially favorably in the range of 1.0 to 2.0 mol. In the case where the amount of the alkylene oxide as charged is less than 1.0 mol, it is unfavorable because the reaction rate falls and by-products increase. When the amount of the alkylene oxide as charged is too much, especially more than 5 mol, it is unfavorable economically.
In the present invention, the reaction between the (meth)acrylic acid and the alkylene oxide in the existence of the catalyst can be performed by a method which is conventionally used for this kind of reaction.
In the case where the reaction is performed by a batch method, the reaction is performed by introducing a liquid alkylene oxide into the (meth)acrylic acid. The alkylene oxide may be introduced after the (meth)acrylic acid is dissolved in a solvent. In this case, the alkylene oxide may be added all at once, continuously, or intermittently. In the case of adding the alkylene oxide continuously or intermittently, as is often the case with this kind of reaction, the reaction can be completed by the so-called aging that is carried out by continuing the reaction after introducing the alkylene oxide. Furthermore, it is not always necessary to add the (meth)acrylic acid all at once in the initial stage, and the (meth)acrylic acid can be added after being divided into some portions.
In the case where the reaction is performed by a continuous method, the reaction is performed by adding the (meth)acrylic acid and the liquid alkylene oxide into a reactor such as a tubular or tank reactor continuously and extracting a reaction liquid out of the reactor continuously. In this case, a catalyst may be provided continuously together with raw materials and b e extracted continuously together with the reaction liquid. In the case of using the reactor such as the tubular reactor, a so-called fixed bed manner in which a solid catalyst as packed with the reactor is used may be utilized. In the case of using the reactor such as the tank reactor, the so-called fluidized bed manner in which a solid catalyst as fluidized together with the reaction liquid in the reactor is used may be used. Furthermore, in the cases of these continuous reactions, modes which allow part of the reaction liquid to circulate may be used.
The reactio
Ishida Tokumasa
Kajihara Tetsuya
Shingai Yasuhiro
Nippon Shokubai Co. , Ltd.
Roylance Abrams Berdo & Goodman L.L.P.
Vollano Jean F.
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