CS220265B1 - Process for preparing a copolymer polyvinyl acetate dispersion - Google Patents

Abstract

The invention relates to the preparation of a copolymer polyvinyl acetate dispersion intended primarily for use in exterior construction, where the dispersions used so far do not meet the established quality requirements. This problem is solved by the present invention by a method for preparing a copolymer polyvinyl acetate dispersion based on polyvinyl acetate-n-butyl acrylate in the presence of polyvinyl alcohol and alkyl polyglycol ether using a peroxybisulphate initiation system. In order to achieve specific properties of the dispersion and the polymer film prepared from it, it is modified after polymerization by adding ethylene glycol, benzyl alcohol, or butyl diglycol acetate. The proposed process can be used to prepare a dispersion that, in terms of quality, meets the requirements for the use of dispersions in construction.

Description

220265 3

The present invention relates to a process for preparing a copolymeric polyvinyl acetate dispersion comprising vinyl acetate-n-butyl acrylate.

Copolymerized polyvinyl acetate dispersions, with either acrylic esters or other comionomers, are usually prepared by emulsifying polymerization. In the emulsifier and protective colloids, the substances used are non-ionic and non-ionic spheres, which are most commonly represented by polyvinyl alkali, or ethylene oxide derivative with propylene oxide, or alkyl polyglycol ether. The polymerization systems also include initiators that improve the efficiency of the use of various activators. It is also possible to influence the properties of the prepared dispersion by the addition of additional milling agents which are typically added to the finished dispersion in order to achieve the desired specific properties. The use of copolymeric polyvinyl acetate dispersions in the construction sector, especially in the exterior, places high dispersion quality and high demands. Not only are the properties of the dispersion dispersed therein monitored, but the quality of the polymer film formed therefrom is monitored by drying under defined conditions. Required values of the following properties: frost resistance, minimum film-forming temperature, viscosity, alkaline hydrolysis resistance, water-absorbability of film, tackiness film, degree of film bleaching, film abrasion resistance and others.

A disadvantage of the known and used processes for the preparation of such dispersions is the fact that neither of them provides a dispersion that meets the requirements for use in the construction industry, especially in exteriors. No. 207,531, which, by defining the ratio of the protective colloid (polyvinyl alcohol anionic emulsifier (alkylpolyglycol ether and their total monomer mixture, using a peroxide initiator system, enhances both the wet abrasion resistance and the resistance to the effect of the alkaline medium.

However, this increase has not been shown to be sufficient, whereby the most significant drawback is the variation of said parameter (abrasion resistance in a substantial range of values, which may be due to the use of an initiator system which is sensitive to the behavior of various technological agents. Furthermore, the film's tackiness, degree of bleaching, and fluctuation of the minimum film-forming temperature towards the unwanted values are further unsatisfactory.

The present invention overcomes the above drawbacks, wherein the preparation of a copolymeric polyvinyl acetate dispersion is effected by copolymerizing a monomeric mixture of vinyl acetate-n-butyl acrylate in an intermediate phase comprising polyvinyl alcohol-protective colloid and an alkylpolyglycol ether nonionic emulsifier with characterized in that a mixture of monomers having a weight ratio of 3.5 to 5.7 relative to vinyl acetate is added to the aqueous phase prepared by dissolving the entire amount of protective colloid and emulsifier at temperatures of above 66 ° C, while the temperature-reacting mixture does not exceed 85 ° C throughout the preparation. Addition of either 0.075 to 0.125% by weight of potassium, sodium or ammonium peroxodisulfate is added in one portion and, after completion of the copolymerization, the pH of the dispersion is adjusted to 4 to 6 with continuous stirring and added From 0.1 to 0.8% by weight of ethylene glycol and from 0.2 to 1.0% by weight of a co-oxidant such as benzyl alcohol, butyldiglycol acetate, or mixtures thereof. The percentage of the components is related to the total weight of the dispersion. The advantage of the above process, as used previously (also in AO alone # 207 531), is that by forming an aqueous phase from all of the components of the emulsion system used, i.e. without further addition thereof in the course of the polymerization and using the pentachloro initiator system, such The appropriate comonomer ratio is formed by the conditions for the formation of polymeric particles of the size and distribution thereof, and the structure of the polymer, which favorably affects the homogeneity of the polymeric film formed from the dispersion and thus its application properties in the desired direction. The following examples further illustrate the invention but do not limit it in any way. Example 1

144.3 L of steam condensate was pumped into the polymerization reactor and 101.5 kg of a 15% K-solution of polyvinyl alcohol at a K-value of 50 + 5, calculated according to Fickentscher, containing residual acetate groups 12, was added. up to 16% by weight and max. cm-1 (trade name Sloviol R). At the same time, 150 kg of a 14% solution of alkyl polyglycol ether characterized by ethylene oxide content 90 + 3% by weight and a hydrophilic-lipophilic balance ratio of 16 to 20 (trade name Slovasol 2430) are added to the reactor.

The aqueous phase thus prepared is heated to 69 ° C and 1/20, i.e. 5% of the total monomer mixture mixture of 80% by weight of vinyl acetate and 20% by weight of n-butyl acrylate, is 21 liters. After 5-10 minutes of 220265 emulsification, the first dose of initiator is added with an amount of 12 L of 5% K2S2O8 solution.

As a result of the reaction, the temperature in the reactor starts to rise. After reaching a temperature of 72 DEG-73 DEG C., the monomer mixture is continuously metered in at a rate of 240 minutes, the temperature of the coating being uniformly raised to 85 DEG. In a 180 minute batch, a batch of 5% initiator solution in an amount of 4 L is added to the batch.

Upon completion of the monomer mixture feed, the dispersion was maintained at the indicated temperature of 85 ° C for 45 to 60 minutes. During this time, the free monomers react and then the reactor contents are cooled to 30 ° C. After cooling, 0.72 kg of 25% NH 4 OH solution was added to the dispersion to adjust pH, 0.8 kegylene glycol and 1.6 kg benzyl alcohol. By thoroughly mixing, the dispersion is filled with fillers. Example 2

Preparation as in Example 1, with the difference that 101.5 kg of 15% polyvinyl alcohol solution, 150 kg of 11.73% of an alkylpolyglycol ether and 6.4 kg of ethylene glycol are used. The peroxodisulfate initiator is used 4 times, the first dose being 8% 15% solution. Another portion was used at 60.180 and 220 min from the start of dispensing the monomer mixture, making the science a 1.6 L of 5% solution. Example 3

The preparation process and the amounts of individual uses of the polymerization system components as in

Table 1 of Table 1 except that the composition of the monomers is 85% by weight of vinyl acetate and 15% by weight of n-butyl acrylate and the benzyl alcohol is added in an amount of 8 kg. Example 4 _ •. .. ... (

The preparation process and the amounts of the individual components of the polymerization system as in Example 1, except that the p-oxodisulfate initiator is used once at the start of the polymerization at 16 L of 15% aqueous solution. Example 5

The preparation process and the amounts of the individual components of the polymerization system as in Example 1 except that the same amount of butyldiglycol acetate was used instead of 1.6 kg of benzyl alcohol. The prepared dispersions evaluated from the starters for use in construction showed qualitatively the values given in Table 1, which do not change significantly during the 6 months following the preparation of the dispersion.

The qualitative indicators achieved correspond to the current highest requirements for the use of the present dispersions in the building industry, especially for the preparation of exterior paints and sprays, plaster and polymer-cement mixtures. The prepared dispersion is also suitable for use as a textiles auxiliary and raw material for the preparation of dispersion adhesives for

Properties of prepared dispersions

Parameter 1 2 Example 3 4 5 Dry matter (% w / w) 52.2 51.7 52.4 51.9 52.1 Freeze resistance Resistant to freezing (cycles at -5 ° C) 5 5 5 5 5. Increased heat resistance (cycles at - (- 60 ° C) 5 5 5 5 5 Foaming (% vol.) 30 38 48 37 40 Min Film forming Temperature ° C + 4 +3 + 2 + 3 + 3 Mechanical Stability equals viscosity (mPa.s) 1700 1000 1600 1540 1450 pH value 5.1 5.0 4.9 4.8 5.0 alkaline resistance (% w / w) 19.7 20.0 15.0 16,1 17,3 water absorption in water (% w / w) 45,4 49,1 48,3 46,7 47,2 film adhesion (g) 10 100 100 10 10 water vapor diffusion through film (μ) 2900 2520 3800 2780 2860 AABAB film bleach grade wet film abrasion (min.) 60 45 45 45 50 film extensibility (% ')' 1000 720 760 860 950 residual monomer (wt%) 0.52 0.47 0.57 0 , 80 0,60 particle size (nm) 170 140 150 164 166 coagulum content (% vol.) 0 0 0 0 0

Claims (1)

220265 OBJECT OF THE PREPARATION OF A COOPERATIVE POLYVYL-ACETIC DISPERSION, BY CO-POLYMERIZING A MODERN Vinyl acetate-N-BUTYL ACRYLATE IN A WATER PHASE CONTAINING POLYSULYBALOBOL AS A PROTECTIVE COLOR AND AN alkyl polyglycol ether as a non-ionic emulsifier by a peroxodisulfate initiator system characterized in that a mixture of monomers, whose mutual composition by weight is determined by a ratio of 3.5 to 5.7 in favor of vinyl acetate to be added to the aqueous phase prepared by dissolving the entire protective colloid and emulsifier at temperatures above 66 ° C, the temperature of the reacting mixture does not exceed 85 ° C throughout the preparation process, adding potassium, sodium or ammonium peroxodisulphate to one or more times of 0.075 to 0.125%, and after the copolymerization is completed, the pH of the dispersion is adjusted while stirring. to 4 to 6 and added 0.1-0.8% by weight of ethylene glycol and 0.2-1.0% by weight of a coalescing agent such as benzyl alcohol, butyl diglyl acetate or mixtures thereof, the percentages of the components being based on the total weight of the dispersion. Sevorografia, n, p., Závod 7, Most Price 2,40 Kčs,