SK21398A3 - Process of preparation of a copolymer dispersion based on vinylester of versatic acid, vinylacetate and acrylate esters - Google Patents

Abstract

A copolymer aqueous dispersion, based on vinylester of versatic acid, vinylacetate and acrylate esters, is prepared by emulsion copolymerization in such a way, that to an aqueous phase components of an emulsion system are dosed which system consists of a protective colloid and a nonionogenic emulsifier, further an electrolyte, and necessary amount of water. After heating the aqueous phase to a temperature of approximately 70 DEG C, a starting dose of a mixture of monomers is added to the aqueous phase, and polymerization reaction is started by adding a predetermined amount of potassium, sodium or ammonium peroxodisulfate. After the starting dose of the mixture of monomers has polymerized, the rest amount of the mixture of monomers is started to be added to the reaction system. After termination of dosing the dispersion is maintained at a temperature of 79 DEG C to 80 DEG C for 30 to 45 minutes, it is cooled down.

Description

Technical field.

The present invention relates to a process for the preparation of an aqueous copolymer dispersion by emulsion copolymerization of versatic acid ester, vinyl acetate and acrylate esters using potassium, sodium or ammonium persulphate, wherein the polymer is characterized by properties that allow its use in external (outdoor) conditions, especially in various applications. in the construction industry, and for the preparation of anticorrosive primers.

BACKGROUND OF THE INVENTION

Emulsion polymerization and copolymerization of vinyl acetate, vinyl esters of versatic acid and acrylate esters, either alone or as co- and terpolymers with various other monomers and with each other, is used to prepare polymer dispersions for both traditional and special applications.

One of the areas of application of aqueous polymer dispersions is the construction sector, where polymer dispersions are used in both exterior and interior applications, especially in paints, as well as as an additive to polymer cement mortars, concrete, renderings, screeds, sealants and building materials. adhesives.

Aqueous copolymer dispersions also find application in the preparation of basic anticorrosive paints.

The use of aqueous copolymer dispersions in exterior façade coatings as well as in anticorrosive coatings imposes high quality requirements on the dispersion and the polymer contained therein. In the past, mainly solvent coating systems have been used in these applications, which are still in use today. At present, however, the most widely used method of protection against external influences, including corrosion, is the application of organic coatings. The development and use of new, constantly improved surface protection systems today is influenced by a number of factors, the most important of which are the environmental and economics of surface treatments. From this point of view, the organic coating must meet the requirements for physiological safety, low or no organic solvent content, no toxic pigments, and applicability independent of environmental influences.

The environmental aspect has been gaining importance in recent years and is a limiting factor in many countries. In the past, attention has been directed primarily to the volatile substances contained in paints. Combating organic solvent emissions has greatly reduced both manufacturers and processors of conventional paints, which are therefore being replaced by water-borne, powdered and high-solid paints.

Building paints form a significant group of water-based paints. They are used for coatings of plaster, concrete, ceramic, fibreboard or wood walls and plasterboard. Both types of paints for construction - exterior and interior, are highly filled paints in which the volume of pigments and fillers (OKP) is 50 to 80%. Thus, they are filled to a higher amount or equal to the Critical Pigment Volume (KOKP) value in the system. The binder (aqueous dispersion) content is in the range of 5 to 25% by weight. The particular amount of binder is dependent upon the ability of the binder to bind pigment and filler particles.

Dispersion paints contain a variety of components which affect the properties of both the paint itself and the film formed after drying. The chemical composition affects the Tg (glass transition temperature), MFT (minimum film forming temperature) values, which have a significant effect on the applicability of the prepared paint. The composition of the polymer also affects the physico-mechanical properties of dry films such as ductility, thermal expansion, flexibility, etc. the resulting film properties can also be influenced by the initiation system used. Likewise, the protective colloid or surfactant can affect the absorbency of the dispersion film to some extent. The choice of a suitable dispersion for the formulation of the paint must be selected with respect to the chemical composition of the dispersion, the initiator system used and the protective colloid or surfactant.

In addition to the above-mentioned requirements for the aqueous polymer dispersion used for the preparation of building (facade) paints, it must contain a polymer which provides the facade paint with desired gloss, adhesion and hardness, low diffusion resistance and water absorption, good washability and high abrasion resistance. A very important criterion is the resistance to UV radiation, which characterizes the effects of the external environment.

Aqueous polymer dispersion suitable for formulating anticorrosive primers should contain a polymer from which the protective film formed after the paint has dried must fulfill the protective function under the action of water and moisture, polluted atmosphere (SO4, Cl), oxygen, elevated temperature and UV radiation ( for the top layers of the system).

Aqueous polymer dispersions belong to a group of substances which fully meet the requirements for the formulation of building and anticorrosive primers from an environmental point of view. It has been shown that by the appropriate composition of the monomer mixture and the polymerization process, the conditions under which the resulting polymer particles and their distribution, as well as the polymer structure, favorably affect the homogeneity of the polymer film formed from the dispersion and hence its application properties in the desired direction. The prepared aqueous copolymer dispersion with the properties and properties of the polymer contained therein is suitable for use in the preparation of exterior (facade) and interior building paints, as well as in the preparation of basic anticorrosive paints.

The present invention provides a process for preparing such an aqueous polymer dispersion.

SUMMARY OF THE INVENTION

According to the invention, a process for the preparation of an aqueous copolymer dispersion based on vinyl versatic acid ester, vinyl acetate and acrylate esters consists in adding to the aqueous phase containing emulsion system and electrolyte components a mixture of monomers of 40-55% w / v of vinyl acetate ester 10 20 - 40% w ^/ w, vinyl acetate, 15 - 25% w / w. methyl methacrylate and Ο - 15% by weight of 2-ethylhexyl acrylate. The initiator system contains an amount of potassium, sodium or ammonium peroxodisulfate

2.3 parts by weight, based on the total polymerization batch, which is 1000 parts by weight.

Examples of the invention

Example 1

The components of the water phase - 18, - masses, parts, ie. 18, - g (as an approximately 10% aqueous solution) of polyvinyl alcohol having a molecular weight given by a K-value of 45-55 calculated according to Fickentscher, containing residual acetate groups 10

- 15% by weight, and a specific conductivity of max. 200 μβ.σπΓ ¹ (trade name Duviol SP-1)., 18, - masses, parts ie. 18, - g (as an approximately 13% aqueous solution) of an alkyl polyglycol ether, characterized by an ethane oxide content of 87-93% by weight and a relative number expressing the hydrophilic-lipophilic balance (HLB) 16

- 20 (trade name Slovasol 2430)., 1,5 masses, parts ie.

1.5 g (as approx. 10% aqueous solution) of NaHCO ₃ and enough water to not exceed the total amount of 478.5 wt. 478.5 g.

The aqueous phase thus prepared is heated with stirring to a temperature of 69-70 ° C and 23.8 parts by weight, i. 23.8 g of the monomer mixture, representing 5% by weight, of its total amount (476.7 parts by weight, ie 476.7 g). The monomer mixture is composed of - 20% by weight, vinyl acetate, 45% by weight, vinyl ester of versatic acid (trademark VeoVa 10), 20% by weight. methyl methacrylate and 15 wt.

2-ethylhexyl acrylate. After 5 to 10 minutes of emulsification, a first initiator dose of 1.5 wt. 1.5 g of potassium persulphate in the form of a 5% aqueous solution. After addition of the initiator, the temperature of the reaction mixture started to rise due to the reaction. After reaching a temperature of 72-73 ° C, the remaining 452.9 parts by weight, i.e. 452.9 g of the monomer mixture, will be continuously metered. Within 140 minutes, the mixture was dosed at a uniform rate of 1.95 wt. 1.95 g per minute. At 140 minutes, the dosing amount is reduced to 1.80 wt. to 1.80 g per minute, which is then uniformly reduced, so that in the last 10 minutes, the monomer mixture is metered at a rate of 0.85 to 0.45 parts by weight, i.e. by weight. 0.85 to 0.45 g per minute. The dosing of the monomer mixture generally takes 270 resp. 300 minutes.

The temperature of the reaction mixture was maintained at 74-76 ° C throughout the dosing period. At 120 minutes of the monomer mixture feed, a second batch of initiator is added to the polymerization batch in an amount of 0.4 wt. 0.4 g of potassium xodisulphate pen, additional portions are added at 150 minutes in an amount of 0.1% by weight, i.e. 0.1 g and then at 180, 210, 240 and 270 minutes, each in an amount of 0.075 wt. 0.075 g of potassium persulfate and in each case as a 5% aqueous solution.

After the monomer mixture is dosed, the polymerization batch is maintained at 78-80 ° C for 30-45 minutes. During this time, the free monomers have reacted and then the reactor contents are cooled to 30-35 ° C. After the dispersion has cooled down, the dispersion is treated by adding 5% by weight of the dispersion. 5 g of ethylene glycol and after thorough mixing, the dispersion is filled into containers.

Quantities of individual components, expressed in mass, parts, resp. in g, are based on 1,000 parts by weight of polymerization feedstock, i.e.. 1 000, - g.

The dispersion prepared as described above has the following quality:

- Dry matter - min. 50, -% by weight - Viscosity (Rheotest) - 2 - 3 Pa.s. - Particle size - 120 - 150 nm - pH - 4-5 - Film forming temperature (MFT) -4 ° C - Absorbency 10 - 30% by weight. - Degree of alkaline hydrolysis 0% by weight. - Abrasion resistance > 45 minutes - Ductility - 800 - 1500%

The dispersion facade coating has the following properties:

- Grip - 1st Grade

- Diffusion resistance - 65 - 80

- Water absorption - 0,02-0,06 kg / m ²

- Hardness - 19 - 25%

- Wet wiping - approx. 5,000 cycles

- After 1000 hours of alternating exposure to UV radiation. rinsing with water, exposure to temperatures of -20 and +50 ° C showed no change in gloss, color, adhesion and weight from the original values.

Example 2

Preparation procedure as in Example 1 except that a mixture of monomers of 40% by weight, vinyl acetate, 40% by weight, vinyl ester of versatic acid (VeoVa 10), 15% by weight was used. methyl methacrylate and 5 wt.

2-ethylhexyl acrylate. The monomer mixture is metered at a constant rate of 1.89 parts by weight, i. 1.89 g per minute, dosing lasting 235 to 245 minutes. The peroxodisulfate initiator is added to 3x, the first dose being 1.5 parts by weight, i.

1.5 g. Another portion is used in the 120th minute of dosing in an amount of 0.5 parts by weight, i. 0.5 g and the last in an amount of 0.3 parts by weight, i. 0.3 g is added when the monomer mixture is dosed. It is always used in the form of a 5% aqueous solution.

The prepared dispersion and the facade coating formulated therefrom exhibit similar properties to those described in Example 1.

Example 3

The preparation process and the amounts of the individual components of the polymerization system as in Examples 1 and 2, except that the composition of the monomer mixture is 20% by weight, vinyl acetate, 55% by weight, vinyl ester of versatic acid (VeoVa 10) and 25% by weight, methyl methacrylate.

The prepared dispersion and the façade paint formulated on the basis thereof exhibit similar properties as in the example

First

Example 4

The preparation process and the amounts of the individual components of the polymerization system as exemplified by the composition of the monomer mixture are 20% by weight, vinyl ester of versatic acid (VeoVa by weight, methyl methacrylate and 5% by weight of 2-ethylhexyl acrylate).

and 2 except that% wt, vinyl acetate, 50% 10), 25%

The prepared dispersion exhibits similar properties to that of Example 1, and the base anticorrosive paint formulated thereon, in addition to the basic properties, meets the requirements of the accelerated NaCl and SO ₂ atmospheric exposure tests.

Industrial usability

Polymer dispersions prepared on the basis of vinyl ester of versatic acid, vinyl acetate and acrylate esters prepared according to the invention extend the possibilities of preparing polymeric aqueous dispersions and are useful in the paint industry and in the construction industry.

Claims (2)

PATENT CLAIMS A process for the preparation of aqueous copolymer dispersions based on vinyl ester of versatic acid, vinylacetate and acrylate esters, by emulsion copolymerization in an aqueous phase containing polyvinyl alcohol as a protective colloid, and alkyl polyglycol ethers such as nonionic emulsifiers effect peroxodvojsíranového initiation of _the characterized in that the mixture monom ^ eq, where the composition is 20% of 40% by weight of vinyl acetate, 40% (55% by weight) of vinyl ester of versatic acid, 15% -25% by weight of (methyl methacrylate) and 15% by weight of 4% by weight. 2-ethylhexyl acrylate is added to the aqueous phase at temperatures above 67 ° C, the temperature of the reaction mixture does not exceed 80 ° C throughout the preparation, with the monomer mixture added at a constant rate for 140 minutes and then uniformly reduced to 0, 85 to 0.45 parts by weight, i. 0.85 to 0.45 g per minute, based on the total batch, at a dosing time of 270 resp. 300 minutes, or dosed at a constant rate for 235 to 245 minutes, adding 3 or more times 2.3 parts by weight, i. 2.3 g of potassium, sodium or ammonium persulphate, based on 1 000% w / w. parts, ie. 1000 g of polymerization batch.