CS266024B1 - Process for preparing a low viscosity aromatic epoxy resin modifier - Google Patents

Abstract

The solution represents a method for preparing a low-viscosity aromatic modifier with a significant diluting effect for epoxy, aliphatic polyamine-cured resins, which consists in heating a mixture of 1 mole of bisphenol A, 0.5 to 5 moles of a phenolic compound, 2.5 to 10 moles of allyl chloride and 2 to 8 moles of KOH or NaOH with a preferred ratio of components of 1:1 to 3:3 to 7:3.5 to 5.5 moles in an aqueous alcoholic solution with stirring for 1 to 8 hours at the boiling point of the reaction mixture, acidifying to pH 5, separating the organic phase from which the volatile components are removed by distillation to a temperature of 100 to 120 °C at a pressure of 3.33 KPa for 1 hour, wherein the phenolic compounds are phenol, and/or halogenophenols and/or alkylphenols with an alkyl size of 1 to 10 carbon atoms and/or resorcinol and/or pyrocatechin.

Description

The invention relates to a process for the preparation of a low-viscosity aromatic modifier of epoxy resins with a significant diluting effect.

To ensure good processability of epoxy resins, their lowest possible 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 weight substances. Organic solvents are mostly volatile from the mixture. Reactive solvents such as glycidethers increase hardener consumption, increase exotherm and are generally harmful to health. Dibutyl phthalate type plasticizers have a high viscosity, often insufficient resistance to dry heat and various chemicals. Dilution with maleic acid esters is also not suitable because their double bonds react with the primary amino groups, thus increasing the aliphatic content in the mass and thus reducing the thermal and chemical resistance. Recently, benzyl alcohol has been used in construction, but it reduces heat resistance.

It has recently been found that modification of bisphenol A allyl ether results in significantly more favorable resistance to dry heat and a number of chemicals as viscosity drops to diisoctyl phthalate levels. However, it turns out that for some application applications it would be necessary to obtain an aromatic modifier with an even lower molecular weight and thus a viscosity.

We have now found that low viscosity aromatic modifiers of epoxy resins can be prepared by reacting 1 mole of bisphenol A, 0.5 to 5 moles of phenolic compound, 2.5 to 10 moles of allyl chloride and 2 to 8 moles of KOH or NaOH, preferably 1 mole of bisphenol. to 3 moles of phenolic compound, 3 to 7 moles of allyl chloride, 3.5 to 5.5 moles of hydroxide in an aqueous-alcoholic medium with stirring and heating for 1 to 8 hours at reflux temperature of the reaction mixture, acidification to pH = 5, separation of organic phase from which the volatiles are removed by distillation to a temperature of 100 to 120 ° C at a pressure of 3.33 kPa. By phenolic compounds we mean phenol and / or alkylphenols of alkyl size up to and / or halophenols, and / or pyrotechnine and / or resorcinol. The modifiers thus prepared are mixtures of allyl ethers of bisphenol A, allyl ethers of phenolic compounds, then in the core of allylated phenols and optionally free phenols and bisphenol A.

The molar ratios of the starting materials and the reaction time can influence the viscosity or the accelerating effects of the modifier. At higher molar ratios of allyl chloride to hydroxyl groups of phenolic compounds, including bisphenol A and their corresponding amounts of KOH (NaOH), products with low viscosity and thus with a significant diluting effect are obtained. If we use a lower molar ratio to the hydroxyl groups of phenolic compounds in the preparation of modifiers so that part of them remains unreacted, we obtain a product with higher viscosity, but also with higher accelerating effects. The reaction time has a similar effect. The longer it is, the more the viscosity and accelerating effects decrease and, conversely, its shortening leads to products with higher viscosity, but also with higher accelerating effects.

The diluting effects of the various aromatic modifiers are given in the following table. This compares the decrease in viscosity of 10% modifier solutions in a low molecular weight 397 low molecular weight palm-type epoxy resin with commonly used modifiers of the same concentration to the viscosity of the resin itself.

epox. resin with epoxy, equivalent. 0.504 mol / 100 g viscosity at 25 ° C in Pa. with 13.40 20% modifier solution from ex. 1 in the above resin 1.13 20% modifier solution from ex. 2 0.82 20% modifier solution from ex. 3 4.20 - 20% modifier solution from ex. 5 1.47 20% bisphenol A bisallyl ether solution 3.20 20% dibutyl phthalate solution 2.10 20% diisooctyl phthalate solution 2.30

Low-viscosity aromatic modifiers are prepared from bisphenol A of standard operating grade, technical phenol, alkylphenols with an alkyl length of 1 to 10, halogen phenols, resorcinol, or mixtures thereof, and from allyl chloride. After mixing in the appropriate molar ratio, 15 to 35% by weight of ethyl alcohol (or another aliphatic alcohol of 1 to 4 carbons) based on the weight of the reaction mixture and the corresponding amount of techn. KOH or NaOH in 2 to 4 times by weight, amount of water based on KOH. The mixture is refluxed with stirring for the required time. After boiling, the reaction mixture is cooled, acidified with dilute HCl or H 2 SO 4 (5 to 25% by weight) to pH = 5 and the upper organic phase is separated. This is freed of volatiles by distillation to a temperature of 100 DEG C. to 120 DEG C. at a pressure of 3.33 kPa for 1 hour. The final product is a brown liquid with a faint aromatic odor. Instead of bisphenol A, other bisphenols or mixtures thereof can be used. Depending on the reaction conditions, various aromatic modifiers can be obtained.

Example 1

A mixture of 228 g (1 mol) of bisphenol A, 188 g (2 mol) of phenol, 382 g (5 mol) of allyl chloride, 600 g of ethyl alcohol and 253 g (4.5 mol) of KOH in 600 g of water is refluxed for 5 hours. . After boiling, the reaction mixture is cooled and acidified with 20% HCl to pH -5. The upper organic phase is separated from the lower aqueous phase and the volatiles are distilled off to 100 DEG C. at a pressure of 3.33 kPa for 1 hour. 540 g of a light brown product with a viscosity of 0.037 Pa.s / 25 DEG C. are obtained, which contains about 80% by weight of allyl ethers of bisphenol A and phenol, 15% by weight, of allylated phenols in the core and about 5% by weight of free phenols.

Example 2

A mixture of 228 g (1 mol) of bisphenol A, 282 g (3 moles) of phenol, 460 g (6 moles) of allyl chloride, 600 g of ethyl alcohol, 200 g (5 moles) of NaOH in 600 g of water is refluxed with stirring for 2 hours. . After cooling and acidifying the reaction mixture to pH = 5, the reaction mixture is worked up as in Example 1. 640 g of a brown product with an average composition of about 70% by weight, allyl ethers of bisphenol A and phenol, 20% by weight, in the core of allylated phenols and about 10% by weight are obtained. % by weight of free phenols. The viscosity is 0.021 Pa.s / 25 ° C.

Example 3

A mixture of 228 g (1 mol) of bisphenol A, 412 g (2 mol) of octylphenol, 382 g (5 mol) of allyl chloride, 600 g of isopropyl alcohol, 224 g (4 mol) of KOH in 600 g of water is refluxed for 6 hours. . Next, the reaction mixture is worked up according to Example 1. 748 g of a brown product with a viscosity of 0.039 Pa.s / 25 ° C are obtained.

Example 4

A mixture of 228 g (1 mol) of bisphenol A, 75 g (0.5 mol) of p-tert-butylphenol, 47 g (0.5 mol) of phenol, 230 g (3 mol) of allyl chloride, 600 g of ethyl alcohol and 168 g (3 mol) of moles) of KOH in 600 g of water is refluxed for 5 hours. Work-up of the reaction mixture according to Example 1 gives 494 g of product with a viscosity of 0.057 Pa.s / 25 ° C.

Example 5

228 g (1 mol) of bisphenol A, 257 g (2 mol) of p-chlorophenol, 500 g of ethyl alcohol, 252 g (4.5 mol) of KOH in 800 g of water and 383 g (5 mol) of allyl chloride are boiled under stirring under reflux. condenser for 2 hours. Shortening of the reaction mixture according to Example 1 gives 625 g of a brown product with a viscosity of 0.027 Pa.s / 25 ° C.

Example 6

A mixture of 228 g (1 mol) of bisphenol A, 110 g (1 mol) of resorcinol, 400 g of ethyl alcohol, 252 g (5 moles) of KOH in 650 g of water and 383 g (5 moles) of allyl chloride is refluxed with vigorous stirring for one hour. . Work-up of the reaction mixture according to Example 1 gives 496 g of a dark brown product with a viscosity of 1.827 Pa ₍ s / 25 ° C.

Claims (1)

Process for the preparation of a low-viscosity aromatic modifier of epoxy resins with a significant diluting effect, characterized in that a mixture of 1 mole of bisphenol A, 0.5 to 5 moles of phenolic compound, 2.5 to 10 moles of allyl chloride and 2 to 8 moles of potassium or sodium hydroxide is heated 1: 1 to 3: 3 to 7: 3.5 to 5.5 moles of these components in an aqueous-alcoholic solution with stirring for 1 to 8 hours at the boiling point of the reaction mixture, acidifying the reaction mixture to pH 5, separating the organic phase from which the volatiles are removed by distillation at 100 DEG to 120 DEG C. under a pressure of 3.33 kPa for 1 hour, the phenolic compounds being phenol, and / or halophenols, and / or alkylphenols having an alkyl size of up to C20, and / or resorcinol and / or pyrocatechin.