CS260559B1 - CoalMMntn Means for Polymer Latexes - Google Patents

Abstract

The essence of the solution is the use of the addition of dinuclear liquid cycloaliphatic ethers, ketones or alcohols, saturated and unsaturated, with a boiling point range of 200 to 280 °C to reduce the minimum film-forming temperature of polymer dispersions (latexes) and enable their processing at temperatures lower than the glass transition temperature of the polymer used. These cycloaliphatic dinuclear compounds can be used individually or in a mixture, or even in a mixture with common organic solvents. It is advantageous to use a mixture of the above substances, obtained by processing distillation residues from the production of cyclohexanone, which contain these compounds. The solution process can be used in the production of paints and spray materials, sealants, adhesives and plastic concrete.

Description

The invention relates to a coalescing agent required to reduce the minimum film-forming temperature of polymeric latexes (aqueous polymer dispersions).

Polymer latexes are prepared by emulsion polymerization and consist mostly of spherical -4-3 polymer particles with a diameter of 10 to 5.10 mm dispersed in water. As a rule, these dispersions also contain emulsifiers, protective colloids, plasticizers, stabilizers, preservatives and fungicides, possibly also a flow aid or a small amount of solvent. After the application of such a polymer dispersion to the substrate, the water or the water is evaporated. after it has been soaked into the substrate, to form a continuous film by sintering the individual polymer particles when the temperature is higher than the so-called minimum film-forming temperature. Below this temperature the film becomes cloudy, white or cracked, or there is no film formation at all. In practice, it is desirable to minimize the minimum film-forming temperature so that dispersions in the form of paints, adhesives, sealants and spray materials can be processed even in cold weather. The minimum film-forming temperature of the latex is always lower than the glass transition temperature of the pure polymer used and serves to evaluate the processability of the latex. It is known that the minimum film-forming temperature can be lowered by the addition of so-called coalescent substances. As coalescing agents, high boiling organic solvents are used which solvate the polymer particles and improve their deformability, thereby reducing the minimum film-forming temperature and facilitating film formation. As a result of their volatility, solvents escape from the film during or after drying and the polymer acquires the original hardness. This results in mechanically stronger and less sticky films than if the addition of non-volatile plasticizers were used to reduce the minimum film-forming temperature.

The solvent used as a coalescing agent should be of low volatility and should not form an azeotropic mixture with water to avoid leakage and loss of action too quickly. It should not cause latex thickening or flammability increase, odor smell, physiologically harmful and very effective in reducing the minimum film-forming temperature. These requirements greatly limit the number of usable solvents. The addition of glycols, glycol ethers, glycol ether esters such as butyl glycol, butyl glycol acetate, butyl diglycol acetate and other high boiling esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is commonly used. Much less effective is the addition of turpentine oil, high-boiling aromatics and gasoline.

We have found that various binuclear cycloaliphatic ethers, ketones or saturated and unsaturated alcohols with a boiling range between 200 and 280 ° C are very suitable coalescing agents for polymeric aqueous dispersions. Cyclohexenylcyclohexyl ether, dicyclohexyl ether, 2- (1-cyclohexenyl) cyclohexanone, 2-cyclohexylidenecyclohexanone, 2-cyclohexylidenecyclohexanol, 2-cyclopentylidenecyclopentanone and their methyl derivatives have proved to be very effective. These dinuclear cycloaliphatic compounds may be used pure and singly or in the form of mixtures artificially prepared or in the form of technical mixtures as found in the distillation residues from cyclohexanone production or in products obtained from such distillation residues by purification and separation operations such as distillation, steam, washing with acidic solutions, etc. The effect of these substances is equal to the effect of the best coalescent agent - butyl glycoacetate, in some latexes it exceeds it. Compared to butyl glycol acetate, the main advantage is the lower cost, especially in the case of products obtained from refinery distillation of cyclohexanone produced from phenol or from distillation residues in refinery distillation of cyclohexanone-cyclohexanol mixture at the end of cyclohexanone production by oxidizing cyclohexane.

The amount in which suitable novel coalescing agents are used depends on the type of polymer dispersion and the desired reduction in the minimum film-forming temperature. 0.1 to 10 wt. %, based on the weight of the aqueous dispersion, but generally 1 to 3 wt. The novel coalescing agents can be combined with conventional and known coalescing agents and organic solvents. These substances are hygienically harmless and their physiological effect corresponds to dibutyl phthalate.

Said coalescing agents can be used to reduce the minimum film-forming temperature of all known types of polymeric aqueous dispersions prepared by the free-radical emulsion polymerization of various unsaturated monomers and mixtures thereof and polymer dispersions prepared by dispersing otherwise synthesized polymers or oligomers in water with the aid of emulsifiers, respectively. protective colloids.

The invention is illustrated by the following non-limiting example.

Exemplary embodiment

To 100 g of Sokrat 2 403 MV commercial dispersion (styrene / butyl acrylate / acrylic acid / methacrylamide emulsion copolymer, manufactured by n.p. Chemické závody Sokolov), a coalescent agent was added in small portions with slow stirring. The mixture was left to stand for two days and after short stirring the minimum film-forming temperature was measured according to the proposed standard CSN 64 9006 (SEVT 36 6282). The temperature was measured by a thermistor touch thermometer. The influence of the coalescent species and amount on the minimum film-forming temperature [^ c] is shown in the table.

Koalescent

Addition of coalescent mass

12 3 5 Dicyclohexyl ether (1) 17

2- (1-cyclohexenyl) cyclohexanone (2) mixture of (1) + (2) + 2-cyclohexylcyclohexanol rainil, cyclohexanone residues, fraction b.v.

100 to 115 ° C at 2.67 kPa dtto, fraction 115 to 125 ° C at 2.67 kPa butylglycol a mixture of dicyclohexyl ether and butyl glycol acetate

8.5

0

1

2,5 1

0

0

1

1

Claims (1)

The use of binuclear cycloaliphatic ethers, ketones or alcohols, both saturated and unsaturated, boiling in the range of 200 to 280 ° C as a coalescent agent for polymer latexes.