RU2522640C2 - Fluorine-containing sas and method of obtaining thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical technology of obtaining fluorine-containing surface-active substances, which can be applied in the field of creation anti-friction compositions, varnish-and-paint materials, water repellents for wide spectrum of materials, compositions for anti-corrosion protection of metals, etc. A fluorine-containing surface-active substance based on diglycerides of perfluorocarboxylic acids, selected from a group of carboxylic acids of hexafluoropropylene oxide dimer or trimmer or their mixture is obtained by carrying out a reaction of glycerol etherification with perfluorocarboxylic acids, selected from a group of hexafluoropropylene oxide dimer or trimmer or their mixture, in the presence of a catalyst, selected from the group: sulfuric acid, orthophosphoric acid, chlorosulphonic acid or sulphonated cation-exchange resins, with a temperature of the reaction mixture being 90 - 120°C and a molar ratio of glycerol to perfluorocarboxylic acid equal to 1:(2-2.1).

EFFECT: invention ensures simplified technology of synthesis of fluorine-containing surface-active substances and reduction of byproducts.

2 cl, 7 ex

Description

The invention relates to chemical technology for the production of organic compounds, namely to fluorine-containing surface-active substances (surfactants) and the method for their preparation. The invention can find application in the field of creating various antifriction compositions, paints and varnishes, water repellents for a wide range of materials, compositions for anticorrosive protection of metals, plastics, rubbers and other materials.

There are various fluorine-containing surfactants and methods for their synthesis, used to create various antifriction compounds, paints, water repellents, metal protection, rubber plastics, etc. areas of application.

A fluorine-containing surfactant is known [1], for which the sodium or potassium salt of perfluoro-4-methyl-3,6-dioxaoctanesulfofluoride is used, and the synthesis of surfactants is carried out by the interaction of perfluoro-4-methyl-3,6-dioxoctanesulfofluoride with an aqueous solution of potassium hydroxide or sodium.

There are various fluorine-containing surfactants based on linear perfluoric acids R _f COOH [2] and perfluoropolyethers - perfluoropolyethers with a terminal acid group at a molecular weight of 2000–5000 amu. [3].

The types of fluorine-containing surfactants considered above are characterized by insufficient stability for a number of technical applications for the adsorption film formed by them on the protected surface.

The closest analogue of the inventive fluorine-containing surfactant and the method for its preparation is fluorine-containing surfactant ethanol 2, 2, 2-tris- [1 ', 1', 1 ', 2', 2 ', 3', 3 ', 5', 6 ', 6 ', 8' - undecafluoro-5 ', 8'-di- (trifluoromethyl) -4', 7'-dioxo-9'-methyleneoxycarbonyl] [4]. A method for synthesizing said surfactant consists in carrying out a reaction between trimer fluoride of hexafluoropropylene oxide and pentaerythritol in an aromatic hydrocarbon solvent and an acid catalyst, followed by separation of unreacted pentaerythritol and solvent and isolation of the pure product by vacuum distillation. This method of producing a fluorine-containing surfactant allows one to synthesize a surfactant whose molecules, in the case of adsorption on the surface, form molecular adsorption films resistant to desorption. The resistance of the formed films to their desorption is explained by the branched structure of the molecule of the surfactant under consideration, due to which, upon its adsorption to the surface, the hydroxyl group is screened by fluorine-containing radicals from reactants (water, amines, phosphorus and sulfur compounds) that can displace the molecule from this surface.

The disadvantage of this method [4] is the formation of ethanol 2, 2, 2-tris- [1 ', 1', 1 ', 2', 2 ', 3', 3 ', 5', 6 ', 6 during the synthesis of a fluorine-containing surfactant ', 8'-undecafluoro-5', 8'-di- (trifluoromethyl) -4 ', 7'-dioxo-9'-methyleneoxycarbonyl] hydrogen fluoride, an extremely dangerous compound, which complicates the industrial technology for producing this surfactant. In addition, in the synthesis of surfactants, other by-products are also formed, such as polyperfluoric acids and mono-, pentaerythritol diesters. The formation of a sufficiently large number of by-products leads to an increased consumption of initial reagents for the development of a unit of the product, thereby increasing its cost.

The technical result of the claimed invention is that the proposed fluorine-containing surfactant is characterized by the ability to form no less stable adsorption films as the surfactant described in [4], and the method for its production is characterized by a lower volume of by-products and the absence of hydrogen fluoride among them. All this simplifies the technology for the synthesis of fluorine-containing surfactants, reduces material costs for the production of the final product and, as a result, reduces its cost.

The technical result is achieved due to the fact that, as a fluorine-containing surfactant, diglycerides of polyperfluorocarboxylic acids selected from a number of carboxylic acids of a dimer or trimer of hexafluoropropylene oxide or a mixture thereof are used, and a method for their synthesis consists in the esterification of glycerol with said acids in the presence of a catalyst selected from the series: sulfuric acid, phosphoric acid, chlorosulfonic acid or sulfonated cation exchange resins, and the esterification is carried out at a temperature of the reaction mixture in the range of 90- 120 ° C and a molar ratio of glycerol: polyperfluorocarboxylic acid equal to 1: (2-2.1).

The synthesis of the proposed fluorine-containing surfactant is as follows. A mixture consisting of glycerol and polyperfluorocarboxylic acid, taken in a molar ratio of 1: (2-2.1), is heated to a temperature of 90-120 ° C in the presence of an acid catalyst. During the synthesis process, water is released, which is continuously distilled off from the reaction mixture in order to shift the chemical equilibrium of the reaction in the direction of obtaining the final product. After the end of the esterification reaction, the reaction mixture is cooled and the catalyst is removed. The liquid catalyst (sulfuric acid, phosphoric acid, chlorosulfonic acid) can be removed by washing the reaction mixture with water, and the solid heterophasic catalyst (sulfonated cation exchange resins) can be removed by filtration. The purified mixture consists predominantly of diglycerides of polyperfluorocarboxylic acids and contains small amounts of unreacted polyperfluorocarboxylic acid and its triglycerides (the total amount of impurities determined by gas chromatography is less than 1%). Cleaning the reaction mixture from these impurities is impractical because they do not reduce the quality of the synthesized surfactant.

The temperature range of the heating temperature of the reaction mixture for its esterification is determined by the fact that, at a lower temperature, the rate of the esterification reaction decreases and the water formed during the reaction is not distilled off. The upper limit of the temperature range for heating the reaction mixture is determined by the fact that at higher values the formation of ethers and polyesters of glycerol occurs. The range of the molar ratio of glycerol to polyperfluorocarboxylic acid is selected based on the following. The ratio of 1: 2 glycerol and acid corresponds to the stoichiometric balance of the reaction for obtaining the inventive fluorine-containing. With an excess of polyperfluorocarboxylic acid, the reaction rate increases, and its time required for the complete conversion of glycerol decreases. An acid content of more than 2.1 mol per 1 mol of glycerol is impractical, since it does not significantly increase the reaction rate of glycerol conversion, but leads to the formation of triglycerides, the excessive content of which degrades the quality of the resulting product and requires additional cleaning operations.

The invention can be illustrated by a number of examples that do not limit other synthesis options of the proposed surfactant, corresponding to the above synthesis method.

Example 1

The reaction mixture in an amount of 300 ml with a molar content of glycerol: carboxylic acid trimer of hexafluoropropylene oxide, equal to 1: 2, and containing 1 ml of 98% sulfuric acid, was placed in a round bottom flask with direct refrigerator. For 12 hours, the temperature in the range of 100-120 ° C was maintained in the flask. After heating, the mixture was allowed to cool to room temperature and washed with distilled water to pH = 6.5.

Example 2

Similar to example 1, but phosphoric acid is used as a catalyst, and the heating time is 14 hours.

Example 3

Similar to example 1, but chlorosulfonic acid is used as a catalyst.

Example 4

Similar to example 1, but the acid used is a carboxylic acid dimer of hexafluoropropylene oxide.

Example 5

Similar to example 1, but as a catalyst used sulfonated ion-exchange resin brand Amberlist 15.

Example 6

Similar to example 1, but the catalyst used is a sulfonated ion-exchange resin brand Amberlist 15. The ratio of glycerol: carboxylic acid trimer of hexafluoropropylene oxide is 1: 2.1. Heating time 11 hours.

Example 7

Similar to example 6, but as the acid used is a mixture of a dimer or trimer of carboxylic acids of hexafluoropropylene oxide, taken in a molar ratio of 1: 1.

In addition, an additional surfactant sample was obtained according to [4]. From each synthesized surfactant sample, its 0.5 wt.% Solution in acetone was prepared with which friction units of a mechanism specially designed for these purposes were processed. The friction unit was a pair of roller plate, which are made of VK20 alloy and operate in dry friction at a temperature of 285 ° C. The resistance of the formed surfactant adsorption film was judged by the operating time of the friction units, until the change in the contact angle of the wetting surfaces of the liquid treated with the fluorine-containing surfactant solution with liquid paraffin. In all cases, this time was approximately equal and amounted to more than 146 hours. Thus, the above data confirm the reliability of the claimed technical result.

Information sources

1. RF patent No. 2041249, 1992

2. The journal "Friction and wear", t.11, N5, p.792; N6, p. 987, 1990

3. The journal "Friction and wear", t.13, N2, p.306, 1992

4. RF patent No. 2083552, 1997 (prototype).

Claims (2)

1. A fluorine-containing surfactant based on perfluorocarboxylic acid diglycerides selected from a series of carboxylic acids of a hexafluoropropylene oxide dimer or trimmer or a mixture thereof. 2. The method of producing a fluorine-containing surfactant according to claim 1 by carrying out the esterification reaction of a polyhydric alcohol with perfluorocarboxylic acids in the presence of a catalyst, characterized in that the synthesis consists in the esterification of glycerol with acids selected from the range of perfluorocarboxylic acids: dimer or trimer of hexafluoropropylene oxide or a mixture thereof in the presence of a catalyst selected from the range: sulfuric acid, phosphoric acid, chlorosulfonic acid or sulfonated cation exchange resins, and esterification iju carried out at a reaction temperature in the range 90-120 ° C and a molar ratio of glycerol: perfluorocarboxylic acid of 1: (2-2.1).