CONTINUOUS AND MODULAR PROCESS FOR PRODUCING WATER-REDISPERSIBLE POLYMER POWDER COMPOSITIONS

Abstract

The invention relates to a method for producing polymer powder compositions which are redispersible in water and which are based on polymerisates of one or more ethylenically unsaturated monomers. In a first step, an aqueous polymerisate dispersion is produced by means of a radically initiated polymerization of one or more ethylenically unsaturated monomers in an aqueous medium, said polymerisate dispersion being convened into the polymer powder composition which is redispersible in water by means of a diving process. The invention is characterized in that the polymerization and the drying process are each carried out in a continuous manner, and the polymerization and the diving process are carried out in separate interconnected modules.

Claims

1. A method for producing polymer powder compositions which are redispersible in water and which are based on polymers of one or more ethylenically unsaturated monomers, comprising: producing an aqueous polymer dispersion by radically initiated polymerization of one or more ethylenically unsaturated mononmers in an aqueous medium; converting the aqueous polymer dispersion to the polymer powder composition, which is redispersible in water, by a drying process, wherein the polymerization and the drying process are each carried out continuously; and conducting the polymerization and the drying process in separate interconnected modules.

2. The method of claim 1, wherein the production is effected by the emulsion polymerization process in the presence of at least one protective colloid, optionally in combination with emulsifiers.

3. The method of claim 2, wherein, after completion of the polymerization and prior to the drying process, no further protective colloids are added to the aqueous polymer dispersion.

4. A modular apparatus for producing polymer powder compositions which are redispersible in water in a continuous process as claimed in claim 1, wherein the continuous process for the production of polymer powder compositions is carried out in separate, interconnected modules.

5. The modular apparatus of claim 4, wherein the modular apparatus is equipped with a polymerization module and a downstream drying module.

6. The modular apparatus of claim 5, wherein the apparatus comprises additional modules having control and infrastructure elements.

7. The modular apparatus of claim 4, wherein the interconnected modules are each transportable units or are assembled from transportable subunits.

8. The modular apparatus as claimed in claims 4 to 7, wherein the modules are connected to a production site via coupling to a local, permanently installed supply network/disposal network, with which the modules can be supplied with substances and/or energy, and/or from which the substances can be dispensed.

9. The modular apparatus of claim 7, wherein the interconnected nodules each have a casing.

Description

[0044] The process according to the invention is shown schematically in the figure. The apparatus comprises a module 1, the polymerization module, and a module 2, the drying module.

[0045] Module 1 is provided with a storage container 1, which is stocked with vinyl acetate monomer, and a storage container 2 for a master batch comprising the further constituents of the polymerization batch. Storage container 2 is kept stocked with a mixture of water, polyvinyl alcohol, initiators and buffer, in the amounts required for the polymerization. The contents of containers 1 and 2 are fed via pumps 6 to a mixer 3, and the mixture generated here is passed into the polymerization reactor 4.

[0046] When the polymerization vessel has been filled with the initial charge, the initial mixture is heated to a polymerization temperature of 70 C., which is maintained during the polymerization by cooling.

[0047] Subsequently, the polymer dispersion formed in polymerization reactor 4 is transferred continuously to the degassing vessel 5. During the polymerization, the amounts of reactant fed continuously to the reactor 4 via the mixer 3 correspond to the amounts which are fed to the degassing vessel 5.

[0048] The polymer dispersion is transferred from the degassing vessel 5 by a pump 6 to the module 2, the drying module, and is heated to a temperature of 90 C. by the heat exchanger 7. The polymer dispersion is introduced into the dryer 8 via an atomizing disk 9. Optionally, further protective colloid, polyvinyl alcohol for example, can be added as drying aid during the drying process via line 13 and pump 14. The air for atomizing the polymer dispersion is fed via line 10 and nozzle 11 to the atomizing disk 9 and heated with the heat exchanger 12.

[0049] The dry polymer powder is removed from the separator 15 and packaged in the packing device 17 into sacks 18. The moist drying air escapes via line 16.

[0050] In this procedure, in addition to the specific investment cost reduced by circa 30%, a dispersion powder is obtained with improved product quality, for example better redispersability.