Method for producing (meth)acrylic acid derivative

Abstract: The present invention provides a method for efficiently using an aqueous solution of (meth)acrylic acid at a low concentration formed in a production/storage step of (meth)acrylic acid. In the present invention, a (meth)acrylic acid derivative is produced by using as a raw material an aqueous solution of (meth)acrylic acid formed by one or both of: a device which reduces a pressure of a gas comprising (meth)acrylic acid in production of (meth)acrylic acid; and a device which collects (meth)acrylic acid from a gas comprising (meth)acrylic acid. (end of abstract)

Agent: Oblon, Spivak, Mcclelland, Maier & Neustadt, P.C. - Alexandria, VA, US
Inventors: Yasushi Ogawa, Shuhei Yada, Yoshiro Suzuki, Kenji Takasaki, Yukihiro Hasegawa
USPTO Applicaton #: #20070060703 - Class: 524804000 (USPTO)
Related Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Involving Inert Gas, Steam, Nitrogen Gas, Or Carbon Dioxide, Processes Of Preparing A Desired Or Intentional Composition Of At Least One Nonreactant Material And At Least One Solid Polymer Or Specified Intermediate Condensation Product, Or Product Thereof, Preparation Of Intentional Or Desired Composition By Formation Of Solid Polymer Or Sicp In The Presence Of Water As A Designated Nonreactant Material (dnrm), Or Products Thereof, Solid Polymer Derived From Ethylenic Monomers Only

Method for producing (meth)acrylic acid derivative description/claims

The Patent Description & Claims data below is from USPTO Patent Application 20070060703, Method for producing (meth)acrylic acid derivative.

Brief Patent Description - Full Patent Description - Patent Application Claims

CROSS-REFERENCE TO A RELATED APPLICATION

[0001] The present application is a continuation of International Application PCT/JP04/016679, filed Nov. 10, 2004, which claims priority to Japanese Patent Application No. 2004-109322, filed Apr. 1, 2004.

[0002] 1. Technical Field

[0003] The present invention relates to a method for producing a (meth)acrylic acid derivative. The present invention more specifically relates to a method for using an aqueous solution of (meth)acrylic acid at a low concentration formed in a production step or a process of storage of (meth) acrylic acid, as a material for production of a (meth)acrylic acid derivative (hereinafter, may also be simply referred to as "derivative") without further purification as (meth)acrylic acid.

[0004] 2. Background Art

[0005] A (meth) acrylic acid-containing gas obtained through vapor-phase catalytic oxidation of propane, propylene, isobutene, or (meth)acrolein is collected in water or in a high boiling point solvent, to thereby form a (meth)acrylic acid solution. The (meth)acrylic acid solution is then subjected to a subsequent purification step involving extraction, diffusion, distillation, and crystallization, to thereby purify (meth)acrylic acid.

[0006] When a vaporization of (meth)acrylic acid as in distillation is involved in the purification step, an operation is conducted under reduced pressure. This is because reduced pressure decreases an operating temperature to suppress polymerization of (meth)acrylic acid. In addition to an operation of reducing pressure, air or a mixed gas of air and nitrogen (hereinafter, may also be referred to as "mixed gas") may be supplied into a system for suppressing polymerization.

[0007] The supplied air or the mixed gas is guided to a vacuum device used for reducing the pressure along with a vapor of (meth)acrylic acid. When a steam ejector is used as the vacuum device, (meth)acrylic acid is trapped in condensed water of a steam discharged from the ejector. When a vacuum pump is used, (meth)acrylic acid is trapped in a seal water thereof.

[0008] An example of a technique of recycling the thus-obtained aqueous solution of (meth)acrylic acid includes a method for circulating the aqueous solution to a collecting step of collecting in the above-mentioned water or the high boiling point solvent crude (meth)acrylic acid formed in production of (meth)acrylic acid or to a purification step thereafter (see JP 2000-351749 A, for example). However, in the method, a large volume of water is circulated along with (meth)acrylic acid, and thus, at least energy required for purification of (meth)acrylic acid from the aqueous solution is further increased.

[0009] Air or the mixed gas is supplied to (meth)acrylic acid stored in a tank for preventing polymerization. The supplied gas is discharged from the tank as a vent gas along with a vapor of (meth)acrylic acid. (Meth) acrylic acid has a strong odor, and thus is usually guided to a deodorization column and trapped in water or an aqueous solution of caustic soda (see "Safety guidelines for handling acrylic acid and acrylates", 5th edition, Japan Acrylate Industry Association, 1997, for example). The thus-obtained aqueous solution of (meth)acrylic acid has been heretofore treated as waste water. Thus, treatment of the aqueous solution of (meth)acrylic acid has involved a loss of (meth)acrylic acid and an increase in load of waste water treatment.

[0010] Meanwhile, JP 2000-351749 A discloses a method for directly introducing a vent gas containing (meth)acrylic acid into the collecting step. However, (meth)acrylic acid is usually produced through a continuous process, and a volume of a vent gas generated from the tank varies depending on receiving or discharge of (meth)acrylic acid. The method may become a variable factor of an operation in a continuous process, and thus is not preferable.

[0011] Further, a vent gas from the tank cannot be recycled while a production process of (meth)acrylic acid is stopped, and the vent gas from the tank must be treated separately.

DISCLOSURE OF THE INVENTION

[0012] The present invention has been made in view of solving the above problems, and an object of the present invention is therefore to provide a method for efficiently using an aqueous solution of (meth)acrylic acid at a low concentration formed in a production/storage step of (meth)acrylic acid.

[0013] The inventors of the present invention have confirmed that concentrations of impurities in an aqueous solution of (meth)acrylic acid at less than 20 mass % formed by trapping in water (meth)acrylic acid vaporized in air or in the mixed gas in a production/storage step of (meth)acrylic acid are substantially lower than that of (meth)acrylic acid.

[0014] The inventors of the present invention have conducted intensive studies based on the fact, and have found that (meth)acrylic acid in the aqueous solution can be used as a raw material for the derivative without disposing or circulating to a purification step, that is, purifying (meth)acrylic acid from the aqueous solution of (meth)acrylic acid, and that cooling of the aqueous solution is effective for the use of the aqueous solution. Thus, the inventors of the present invention have completed the present invention.

[0015] That is, the present invention is a method for producing a (meth)acrylic acid derivative, which comprises using as a raw material an aqueous solution of (meth)acrylic acid formed by one or both of: a device which reduces a pressure of a gas comprising (meth)acrylic acid in production of (meth)acrylic acid; and a device which collects (meth)acrylic acid from a gas comprising (meth)acrylic acid.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] In the present invention, a (meth)acrylic acid derivative is produced by using as a raw material an aqueous solution of (meth)acrylic acid formed by one or both of: a device which reduces a pressure of a gas comprising (meth)acrylic acid in production of (meth)acrylic acid; and a device which collects (meth)acrylic acid from a gas comprising (meth)acrylic acid. The term "(meth)acrylic acid" refers to acrylic acid or methacrylic acid. Further, the phrase "an aqueous solution of (meth)acrylic acid" refers to an aqueous solution of (meth)acrylic acid formed by trapping in water (meth)acrylic acid vaporized along with air or a mixed gas of air and nitrogen used in a production and storage step of (meth)acrylic acid.

[0017] A known device for reducing a gas pressure can be used for the device which reduces a pressure of a gas. Examples thereof include: a kinetic vacuum pump such as a steam ejector involving gas transportation by an entrainment effect of a working fluid (steam) blowing at high speed; and a liquid ring pump such as a normal vacuum pump involving sealing of a liquid (water) by discharging air in a casing.

[0018] Examples of the aqueous solution of (meth)acrylic acid formed by the device which reduces a pressure of a gas include: a condensed water of a vapor used for a steam ejector; and a seal water of a vacuum pump.

[0019] A known device for collecting a predetermined component in a gas can be used for the device which collects (meth)acrylic acid. An example thereof includes a deodorization device for collecting in water (meth)acrylic acid from a gas to deodorize the gas such as a packed column, a plate column, a spray column, and a scrubber.

[0020] An example of the aqueous solution of (meth)acrylic acid formed in the deodorization device includes a water used for collecting (meth)acrylic acid in the deodorization device.

[0021] The above-mentioned aqueous solution of (meth)acrylic acid may be used alone or may be used as a mixture of a plurality thereof.

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