CS211647B1 - A method for preparing a copolymer polyvinyl acetate dispersion - Google Patents

Abstract

The invention relates to a method for preparing a copolymeric polyvinyl acetate dispersion suitable for preparing pigmented paper paints. The problem is solved by copolymerization of monomers in the presence of ethoxyl surfactants, namely alkyl polyethylene glycol ether and alkali salts of phosphoric acid esters with alkyl polyethylene glycol ethers in the presence of salts of carbonic and phosphoric acids. Acrylic acid esters are used as vinyl acetate monomers. The dispersion prepared by the proposed method allows the preparation of pigmented paper paints containing 50 to 60% by weight of non-volatile fraction. with suitable flow properties.

Description

The invention relates to a process for the preparation of a copolymeric polyvinyl acetate dispersion, to the requirements for dispersions thereof, to the use of the preparation of pigmented paints for paper and board coating are influenced by the process for preparing and applying paint and the desired properties of the coated paper or board.

The presence of the dispersion in the paint affects such important properties as its flow behavior and water retention capacity. The dispersion also plays a significant role in the qualitative properties of the surfaces of paper or board treated with pigment paints.

Pigment paints prepared using polyvinyl acetate dispersions containing protective colloids (e.g. polyvinyl alcohol, cellulose derivatives) exhibit an unsuitable high apparent viscosity even at a relatively low solids content as well as a dilatant flow and high thixotropia.

Using certain polyvinyl acetate dispersions not containing a protective colloid, it is possible to prepare pigmented paints having satisfactory properties in the range of medium solids contents (40 to 50% by weight). At higher solids contents (in the range of 50 to 60% by weight), the apparent viscosity increases rapidly, and their flow properties deteriorate and thus cease to meet the requirements.

These drawbacks are overcome by the synthetic copolymer polyvinyl acetate dispersion prepared by the present process which, unlike other polyvinyl acetate dispersions! enables the preparation of pigment paints with a higher solids content (up to 60% by weight).

Treated paper or paperboard surfaces obtained by applying paints prepared using the copolymeric polyvinyl acetate dispersion prepared by the present process are characterized by improved calenderability, air and water vapor permeability and, in the case of paperboard, also with higher rigidity while maintaining the other desired properties.

A process for preparing a copolymeric polyvinyl acetate dispersion by emulsion copolymerization of the monomers of the present invention comprises copolymerizing 500 parts by weight of a mixture of vinyl acetate and an alkyl acrylate containing C 2 to C 8 alkyl in a weight ratio of vinyl acetate to alkyl acrylate of 10: 1 to 3: 2; in the presence of 15 to 40 parts by weight alkylpolyetylénglykolétéru-containing alkyl group and a 20 to 40 moles of ethylene oxide per Raolia alkyl, 1 to parts by weight of the sodium or potassium salts of phosphoric esters of alkylpolyetylénglykoléterrai containing alkyl _C10 and 3 to 10 moles of ethylene oxide per mole of alkyl and 0 5 to 5 parts by weight of primary and / or secondary, sodium and / or potassium salts of phosphoric acid and / or carbonic acid.

The dispersion prepared according to the present invention has the following properties: non-volatile content 50 to 55% by weight, viscosity 13 to 100 mPa.s, pH in the range 3 to 6, unreacted monomers content max. 1 By weight, frost-resistance up to -7 ° C and particle size in the range of 160 to 250 nm. The pigmented paint prepared using said dispersion exhibits a pseudoplastic flow and low thixotropy. The prepared paints exhibit favorable apparent viscosity values even at higher solids content. The colors retain their properties even at pH 11 to 11.5 in the presence of satin white. ^x

211.647

Example '1'

In a four-necked 1.5 liter sulfonation flask, an aqueous phase is prepared consisting of 460 parts by weight of water, 40 parts by weight of alkylpolyethylene glycol ether containing alkyl and 40 moles of ethylene oxide per mole of alkyl, 4 parts by weight of alkylpolyethylene glycol ether and sodium ethoxide containing sodium ethylate. per mole of alkyl, from 0.6 parts by weight of Na 2 HPO 4, from 0.5 parts by weight of HPO 4, from 0.8 parts by weight of Na 2 CO 4, and from 0.5 parts by weight of MaHCO 3, which is heated to 70 ° C.

At this temperature ea, 1.5 parts by weight of ^Κ 2 2 2θ8 are added, ^and 50 parts by weight of a mixture of vinyl acetate and butyl acrylate in a weight ratio of 3: 1 are added uniformly over a period of 240 minutes at 75 ° C. When the monomer feed is complete, the dispersion temperature aa is raised to 80 ° C and after the vinyl acetate content of the dispersion has fallen below 1 X by weight, the dispersion is cooled to 20 ° C.

The properties of the dispersion are as follows; a non-volatile content of 53.8% by weight, a viscosity of 40 mPa.s, a pH of 5 and an average particle size of 180 nm.

and

Example 2 '

The procedure as in Example 1, except that the aqueous phase consists of 460 parts by weight of water, 20 parts by weight of an alkylpolyethylene glycol ether containing C 1 to C 18 alkyl and 25 moles of ethylene oxide per mole of alkyl, 5 parts by weight of sodium alkylpolyethylene glycol ether phosphate containing C 1-6 alkyl. of ethylene oxide per mole of alkyl-α in 2.5 parts by weight

The 500 parts by weight monomer mixture used contains 9: 1 vinylacetate and octyl acrylate »

The properties of the dispersion are as follows: non-volatile content 52% by weight, viscosity 20 mPa.s, pH x 5.5 and average particle size 230 nm.

Example 3. The procedure as in Example 1 except that the aqueous phase consists of 450 parts by weight of water, 30 parts by weight of alkylpolyethylene glycol ether containing alkyl Cp and 40 moles of ethylene oxide per mole of alkyl, 8 parts by weight of alkylpolyethylene glycol ether phosphate and 5 parts by weight of Na2HPO4. The 500 parts by weight of monomers used consist of 3: 2 vinyl acetate and ethyl acrylate.

The dispersion properties are as follows: non-volatile content 54% by weight, viscosity 32 mPa.s, pH 5.5 and average particle size 170 nm.

Example 4

Example 1, except that the aqueous phase consists of 480 parts by weight of water, 15 parts by weight of an alkylpolyethylene glycol ether containing C 18 to C 18 alkyl and 40 moles of ethylene oxide per mole of alkyl, 2 parts by weight of a alkyl alkyl polyethylene glycol ether phosphate containing a and 4 moles of ethylene oxide per mole of alkyl and up to 2 parts by weight of K2HPO4.

The 500 parts by weight monomer mixture used consists of vinyl acetate and hexyl acrylate in a 6: 1 weight ratio.

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The properties of the dispersion are as follows: non-volatile content 50% by weight, viscosity 20 mPa · s, pH 4.5 and average particle size 250 nm.

Claims (1)

A process for the preparation of a copolymer polyvinyl acetate dispersion by emulsion copolymerization of monomers, characterized in that the copolymerization of 500 parts by weight of a mixture of vinyl acetate and an alkyl acrylate containing C8 to C8 alkyl in a weight ratio of vinyl acetate to alkyl acrylate of 10: 1 to 3: 2 is realized in the presence of 15 to 40 alkylpolyetylénglykoléteru comprising alkyl, C "and C, and _a 20 to 40 ethylene oxide per mole Raolia alkyl, 1-8 UIO 1 _(by weight of the sodium or potassium salts of phosphoric esters of alkylpolyetylénglykolétermi obsahujdeirai C ^ q alkyl and a 3 to 10 moles of ethylene oxide per and 0.5 to 5 parts by weight of primary and / or secondary, sodium and / or potassium salts of phosphoric acid and / or carbonic acid.