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Continuous process for preparing polymers

Inactive Publication Date: 2001-12-13
ROHM & HAAS CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] According to a second aspect of the present invention there is provided a method for reducing polymer fouling during a continuous process for preparing a polymer including continuously feeding at least one reaction mixture containing at least one monomer to a reactor wherein the reactor does not contain a gas phase; polymerizing the monomer in the reactor; and continuously removing the polymer from said reactor.
[0021] In another embodiment the reactor consists of non-cylindrical channels and alternating channels for the temperature control medium which may be, for example, certain types of heat exchangers such as plate-frame, plate-fin, and spiral-plate heat exchangers. The plate-frame heat exchanger consists of standard plates which may be flat or corrugated. Corrugated plates are preferred due to improved mixing of the monomer with the other reactants. The plates serve as heat exchange surfaces and may be made of stainless-steel types 304 and 316; titanium, Monel, Incoloy 825, Hastelloy C, phosphor bronze, and cupronickel. The plates may be coated with materials such as graphite or polytetrafluoroethylene. The plates form alternating non-cylindrical channels for the reaction mixture containing at least one monomer and the temperature control medium to flow through. The plates are supported by a frame. Gaskets prevent leakage where the plate and frame meet. The frame may be made of clad stainless steel and enamel-coated mild steel.

Problems solved by technology

Such processes are susceptible to various degrees to polymer build-up or fouling on the reactor surfaces.
Polymer fouling results in the need to shut the reactors down and clean the reactor surfaces which reduces available production time and may, for certain reactor geometries such as tubular reactors, be highly inconvenient.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0032] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g / min from a 3.6 L tank to an evacuated premixer (Cornell Model D-8 Versator with a vacuum of 55.9 mm(22 in) water). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g / min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia / 13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in an evacuated chamber at 61.0 mm(24 in) water. The aqueous catalyst feed tanks were sparged with N2. The buffer feed tank was swept with N2.

[0033] D...

example 2

[0041] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g / min from a 3.6 L tank to an evacuated premixer (Cornell Model D-8 Versator with a vacuum of 55.9 mm (22 in) water). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g / min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia / 13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in an evacuated chamber at 61.0 mm (24 in) water. The aqueous tanks were sparged with Helium. The buffer feed and catalyst tanks were swept with Heli...

example 3

[0045] A monomer mixture (46% butyl acrylate, 53% methyl methacrylate, 1% methacrylic acid) was fed at 58.5 g / min from a 3.6 L tank to an evacuated premixer (Cornell Model D-8 Versator with a vacuum of 55.9 mm (22 in) water). An aqueous mixture (1.4% anionic surfactant) was fed at 11.4 g / min from a 7.6 L tank to the pre-mixer. The pre-mixer was set to a speed such that a stable monomer emulsion was produced. A 20 L aqueous feed tank was used to feed hot DI water to the front of the process. A 10% ammonium persulfate catalyst solution was prepared. The solution was mixed well and fed to the catalyst feed tank. A 1.2% aqueous ammonia / 13.8% sodium laurel sulfate buffer solution was prepared. The solution was mixed well and fed to the buffer feed tank. The aqueous feeds were fed through 18 feet of peroxide cured gas permeable tubing coiled in an evacuated chamber at 24" water. The aqueous, catalyst feed tanks were sparged with N2. The buffer feed tank was swept with N2.

[0046] DI water w...

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Abstract

A continuous process for preparing polymers, preferably emulsion polymers, with minimal fouling of the reactor is provided. The process is effected in a reactor which does not contain a gas phase, optionally by reducing the gas content of the reaction mixture.

Description

[0001] This invention relates to a continuous process for preparing polymers and a method for the reduction of polymer fouling on reactor surfaces, especially in a continuous process for preparing emulsion polymers.[0002] Polymers are typically prepared in batch, semi-continuous, or continuous processes. Such processes are susceptible to various degrees to polymer build-up or fouling on the reactor surfaces. Polymer fouling results in the need to shut the reactors down and clean the reactor surfaces which reduces available production time and may, for certain reactor geometries such as tubular reactors, be highly inconvenient.[0003] European Patent Application 926 161 A discloses a continuous process for preparing polymers in a reactor having a non-cylindrical channel which provides low levels of fouling. Even lower levels of fouling are desired.[0004] "Effects of Dissolved Gas on Emulsions, Emulsion Polymerization, and Surfactant Aggregation" by M. E. Karaman, et al. J. Phys. Chem,...

Claims

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Application Information

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IPC IPC(8): C08F2/00C08F2/22
CPCC08F2/22Y10S526/918
Inventor FITZWATER, SUSAN JANEMCFADDEN, DAWN MARIE
Owner ROHM & HAAS CO
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