CS244709B1 - Process for preparing condensation products - Google Patents

Abstract

Improving the application properties of condensation products of cresol isomers and sodium sulfite with formaldehyde in an aqueous medium by modifying the resulting condensate in an alkaline medium with 1-naphthalenesulfonic acid, optionally with the addition of nonylphenol.

Description

The present invention relates to a process for the preparation of condensation products suitable, in particular, for dispersing organic dyes and pigments by wet grinding and for stabilizing fine dispersions in an aqueous alkaline, neutral or acidic environment at temperatures of 10 to 130 ° C.

A long range of dispersants is currently used to disperse colorants that are almost or totally insoluble in water. So far, the most commonly used formulations are classified either as condensation products of aromatic compounds containing sulfo groups, or in differently treated ligninsulfonates. Typically, many ligninsulfonates do not impart sufficient dispersion stability to hot dispersions. Other dispersing agents are effective only in the alkaline range and stain or stain the fiber, which is an obstacle to achieving bright shades. Finally, a considerable number of dispersants do not achieve sufficient dispersing and leveling effectiveness in dyeing due to the high sudsing properties.

The preparation process, one of the most commonly used conventional preparations so far, consists of two-phase condensation of cresol, sodium 2-naphthol-6-sulfonic acid and sodium sulfite with formaldehyde (FIAT report 1 013). However, its good dispersing and stabilizing properties remain only in an alkaline environment. In an acidic environment, the product exudes from the solution in a gel-like manner and deteriorates the feel of the textile fiber.

These drawbacks eliminate the condensation products prepared by the condensation of a mixture of three cresol isomers and sodium sulfite with formaldehyde in an aqueous process according to the invention, such that the condensation is carried out at pH 8-11 and at 80-140 ° C in the presence of 1-naphthalenesulfoacids; the molar ratio of cresol: sodium sulphite: formaldehyde: 1-naphthalenesulfonic acid falls within the range of 1: 0.3 to 1.2: 1.1 to 2.9: 0.2 to 0.35

Preferably, 1-naphthalenesulfoacid may be used with the addition of nonylphenol, the molar ratio of cresol: nonylphenol being in the range of 1 to 0.01 to 0.15.

The cresol fraction used may preferably contain 5 to 18% of the ortho isomer, 30 to 50% of the meta isomer and the remainder of the para-isomer.

Preparations prepared in this way have the following advantages:

(a) Condensation of cresol, 1-naphthalenesulfoacid and sodium sulphite with formaldehyde may be carried out in a single-phase production cycle.

(b) the presence of 1-naphthalenesulfoacid reduces the alkalinity of the reaction medium as determined by the sodium sulfite present. By effectively reducing the alkalinity, the required amount of sulfuric acid in the neutralization and thus the sodium sulfate content of the product is reduced.

c) Preparations with condensed 1-naphthalenesulfoacid show excellent solubility even in strongly acidic environments without the tendency to gel.

d) Said preparations permit a high concentration of the liquid product, since its neutralization does not increase but neutralizes its viscosity. The high concentration of the product then provides convenient production and shipping capacity.

e) In a neutral and slightly acidic environment, the product is very light and does not become dark.

d) In general, it has good grinding, stabilizing and leveling properties in alkaline, neutral and acidic environments.

Example 1

170 parts of crystalline sodium sulfite are dissolved in 135 parts of water at 34 ° C with the addition of 146 parts of 37% formaldehyde and 108 parts of techn. pure tricresol fractions containing 30-45% m-cresol and 70 parts of a 60% 1-naphthalene sulfoacid solution. The reaction mixture is slowly warmed to 96 ° C over 2 hours with optional warming and is maintained at a gentle boiling point for a further 10 hours at 96-98 ° C.

After cooling to 90 ° C, the mixture is neutralized hot with 50% sulfuric acid until neutral with a 10-fold diluted water sample.

Yield 628 parts approximately 43% of the product with 270 parts solids.

Example 2

170 parts of crystalline sodium sulfite are dissolved in 185 parts of water at 34 ° C with the addition of 165 parts of formaldehyde 37% and 108 parts of techn. pure tricresol fractions containing 30-45% m-cresol, 11 parts nonylphenol and 70 parts 60% 1-naphthalenesulfoic acid solution. The reaction mixture is slowly warmed to 96 ° C over 1 to 2 hours with optional heating and maintained at 96 to 98 ° C under gentle reflux for a further 10 hours. After cooling to 90 [deg.] C., it is neutralized hot with 50% sulfuric acid until neutral by a tenfold dilution of water. Yield 720 parts 41% product with 295 parts dry matter.

The products are used to disperse by wet milling in a conventional manner.

Claims (2)

Process for the preparation of condensation products by condensation of a mixture of three cresol isomers and sodium sulfite with formaldehyde in an aqueous medium, characterized in that the condensation is carried out at a pH of 8-11 and at a temperature of 80-140 ° C in the presence of 1-naphthalenesulfoacids cresol: sodium sulfite: formaldehyde: 1-naphthalenesulfoacid falls within the range of 1: 0.3 to 1.2: 1.1 to 2.9: 0.02 to 0.35. 2. A process according to claim 1, wherein the condensate is reacted with 1-naphthalenesulfoacid with addition of nonylphenol, wherein the molar ratio of cresol: nonylphenol falls within the range of 1: 0.01 to 0.15.