CS271828B1 - Method of pentaerythril-tetrakis-/-3-/3,5-ditere-butyl-4-oxophenyl/propionate production - Google Patents

Abstract

A method of obtaining pentaerythryl-tetrakis-[3-(3,5-ditert.butyl-4-oxyphenyl)propionate] by means of reetherification of methyl ether 3-(3,5-ditert. butyl-4-oxyphenyl)propionic acid in the presence of an alkaline catalyst at a temperature of 115-160 DEG C and at a pressure of 0.66-13.3 kPa. As alkaline catalyst a mixture of potassium carbonate, sodium carbonate and phenic acid is used at a weight ratio of 1:1-2:2-3, respectively, the catalyst being used in a quantity of 6-10 % of the initial weight of methyl ether. The product obtained is a highly effective non-toxic antioxidant for polymer materials.

Description

The invention relates to a process for the preparation of a low-reactive reactive solvent of epoxy resins based on condensates of aliphatic ketones with monoethanolamine.

In order to ensure good workability of epoxy resins, their lowest viscosity is required. This depends on the temperature, the relative molecular weight of the resin, its reactivity with the hardener, etc. In general, a reduction in viscosity can be achieved by the addition of low-molecular substances. Organic solvents are volatile from the mixture. Glyoidyl ether reactive solvents increase hardener consumption, increase exotherm and are harmful to health. Dibutylphthalate thinners have a high viscosity, often insufficient resistance to dry heat and various chemicals. Recently, benzyl alcohol has been used in the construction industry, but it reduces the heat resistance. The low viscosity results in better processability and bubble escape, easier mold filling and higher refillability. The optimum reactive solvent should have a strong dilution effect, guaranteed by its low viscosity up to 25 Pa.s at 25 ° C and low molecular weight at the highest possible boiling point.

However, in order to maintain the original properties, the addition of the reactive solvent is as compact as possible. An important requirement for a reactive solvent is that it contains a reactive group to participate in the cure while being as toxic as possible. Reactive solvents often increase the heat of reaction by their own reaction. In the case of acrylates, for example, the double bond reacts four times faster with amines than the epoxy resin, thus limiting the size of the possible casting or complicating the technological conditions. The most effective reactive solvent is styrene. However, its use is abandoned for health reasons. Glycyl ethers have a detrimental effect on the skin and mucosa. Acrylates also damage the respiratory mucosa by inhalation. The danger of acrylates is strongly dependent on its molecular weight, and liquid causes skin inflammations, especially during prolonged exposure. Conventional palm epoxides provide rigid, rigid, sometimes brittle materials by curing with conventional hardeners, which, in conjunction with materials with other volumetric thermal expansion, have considerable internal stress and often lead to cracking of the castings. These drawbacks of DC are mainly manifested when applied to products of larger sizes in insufficient resistance to low temperatures, impact, etc. The use of reactive solvents usually results in flexlbilization.

We have now found that some of these problems can be solved by using a low viscosity reactive solvent of epoxy resins, obtainable by reacting aliphatic ketones with ethanolamine in a molar ratio of 1 to 1.2: 1 in the presence of cyclohexane or toluene as solvent for azeotropic dewatering. the cyclohexane (toluene) was distilled off at normal pressure, and the residue was then pressurized to 90 ° C (50 psi). Aliphatic ketones are ketones having a carbon number of 3 to 9. The products consist of colorless to yellow-brown liquids, with a slight terpenic odor. Amine number = 475 to 280 mg KOH / 1 g, viscosity 0.0029 to 0.037 Pa.s / 25 ° C.

The reactive solvent obtained in this manner can be introduced into the composition as a separate component or as a solution thereof in an oxide resin or hardener. Due to the low reactivity of the amine secondary group with the epoxy group, a slow increase in viscosity has to be expected.

The advantage of the solution according to the invention is to obtain a reactive solvent with a low viscosity, which brings better processability and a decrease in the viscosity of the epoxy resins, as well as health safety during longer handling of the compositions in which it is contained.

The raw materials for the preparation of reactive solvents are primarily acetone, furthermore methyl ethyl ketone and diisobutyl ketone. However, all aliphatic ketones having up to 9 carbons, including mixtures thereof, may be used. The aliphatic ketones are refluxed with ethanolamine of conventional quality under azeotropic dewatering using cyclohexane or toluene at a molar ratio of 1: 1. After distilling off the solvents, the front part is distilled to 90 ° C at 3.33 kPa. In the case of aoetone, the reaction mixture must be rectified on a column, but not necessary for the other ketones.

CS 271828 Bl

The formation of N-hydroxyethylimines and oxazolidines is known from the general reactions of a carbonyl group with 1,2-aminoalcohols. In the case of reaction of aliphatic ketones with ethanolamine, the products will be of the same type. The composition of the reaction mixture is not known, nor is the procedure by which the complicated reaction mixture could be analyzed.

Example 1

A mixture of 183 g of athanolamine (3M), 197 g of acetone (3.4M) and 100 g of cyclohexanone is boiled under azeotropic dewatering of the reaction mixture. After separating 54 g of water, the reaction mixture is worked up by distillation on a Vigreux column. Acetone and cyclohexane were separated under normal pressure, and the product was collected at 35-50 ° C (230 g) at a pressure of 50 psi. It forms a clear, colorless liquid with a viscosity of 0,0029 Pa · s and an amine number of 475,4 mg KOH / 1 g. a resin having a viscosity of 2.2 Pa.s / 25 ° C is obtained.

Example 2

A mixture of 183 g of ethanolamine (3M), 284 g of methyl isobutyl ketone (3M) and 100 g of cyclohexane is boiled under azeotropic dewatering of the reaction mixture. After separating 54 g of water, cyclohexane is distilled off from the reaction mixture at normal pressure, and a front pressure of 90 DEG C. is distilled off at a pressure of 50 psi. The product is a yellowish liquid, tapernic fragrance (387 g). The viscosity is 0.020 Pa.s, the amine number is 362.6 mg KOH / 1 g. By homogenizing 90 g of an epoxy resin with an average molecular weight of 395, a viscosity of 16.3 Pa.s / 25 ° C and 10 g of product, a resin with a viscosity is obtained. 2.9 Pa.s / 25 ° C,

Example 3

A mixture of 122 g of ethanolamine (2M), 284 g of diisobutyl ketone (2M) and 80 g of cyclohexane is boiled under azeotropic dewatering until 36 g of water are distilled off. Thereafter, cyclohexane and the front are distilled off as in Example 2. The product consists of 340 g of a light brown liquid with a viscosity of 0.037 Pa · s and an amine number of 280 mg KOH / 1 g. resin with a viscosity of 3.8 Pa.s / 25 ° C.

Claims (1)

A process for the preparation of a low viscosity reactive solvent of epoxy resins, comprising boiling a mixture of aliphatic ketones with monoethanolamine in a molar ratio of 1 to 1.2: 1 under azeotropic dewatering with cyclohexane or toluene, then cyclohexane or toluene distilled from the reaction mixture under normal pressure; overhead stream at a pressure of 3.33 kPa and the temperature ^90? C with aliphatic ketones means a ketone of carbon number 3 to 9