CS272822B1 - Low-viscous reactive epoxy composition - Google Patents

Abstract

The solution concerns a formulation of low-viscosity reactive epoxy composition containing non-toxic reactive solvent based on monoethanolamine and cycloaliphatic ketones. The low-viscosity reactive epoxy composition is prepared by homogenisation of 100 weight parts of epoxy resin with average molecular mass form 360 to 600 that contains 25 percent by weight of outer or inner plasticizing agent, from 1 to 30 weight parts of cycloaliphatic ketone condensate with monoethanolamine with amine number from 290 to 390 mg KOH/g and aliphatic aminic hardening agent in quantity from 60 to 120 percent of theory related to the contents of reactive groups in used epoxy resin.

Description

The present invention relates to a low-viscosity reactive epoxy composition comprising a novel non-toxic reactive solvent based on cycloaliphatic ketone and monoethanolamine condensates.

The viscosity of low molecular weight palm epoxy resins is typically 8 to 20 Pa.s / 25 ° C Pa.s / 25 ° C. This is too high for many applications and is therefore often adjusted by the addition of suitable reactive and non-reactive low molecular weight substances. The low viscosity results in better processability and bubble escape, easier mold filling and higher refillability.

When selecting a suitable reactive solvent, the reaction is carried out. apply two opposing needs. Usually, low molecular weight substances have a greater dilution effect. Iy, however, tend to have a higher vapor pressure, which complicates work safety measures. Reactive solvents have a great advantage over non-reactive solvents - the incorporation into a network of hardened material. Therefore, they do not escape from matter over time. Their reactivity to participate in networking is often dangerous from a toxicological point of view. The optimum reactive solvent should have a strong dilution effect guaranteed by its low viscosity up to 25 mPa · s and low molecular weight at the highest possible boiling point. In order to maintain the original properties, the addition of the reactive solvent is as low as possible. Further, a reactive group is required to participate in the claim but with low toxicity. Reactive solvents often increase the heat of reaction by their own reaction. In the case of acrylates, the double bond reacts about four times faster with amines than the epoxy groups of the resin, thereby limiting the size of the possible casting or complicating the process conditions. At the same time, the processability (scrubbing) of the composition and the fillability, especially with non-conductive fillers, are shortened. The addition of the primary amines proceeds rapidly - even at ambient temperature; the secondary amines require a longer time even at elevated temperature. The response is considerably prolonged. The advantage of the reaction of the primary amines with a double bond is due to incomplete reaction of dibutyl maleate or 2-ethylhexyl acrylate, some of which remains extractable.

The most effective reactive solvent is styrene. However, its use is abandoned for health reasons. - The disadvantage of glycidyl derivatives, the most commonly used glycidyl ethers, are adverse effects on the skin and mucous membranes. Direct contact causes irritation of the skin. They may develop up to watery blisters, especially where the skin is unholy and occasionally steamy (under the rings, between the fingers). Their vapor irritates the eyes, causing conjunctivitis, as well as mucous membranes of the upper respiratory tract. These effects are cumulative in more sensitive people. Inhaled acrylic vapors also damage the mucous membranes of the airways. Acute poisoning can result in death due to nerve tissue disruption, internal bleeding and pathological changes in various organs. The hazards of acrylates depend strongly on the molecular weight of the acrylates. Liquid acrylates cause skin inflammations, especially during prolonged exposure, and conjunctivitis. If glycidyl ethers above C 1 are used which are less toxic, their dilution effect is significantly weaker. The situation is similar with esters with double bond.

Conventional Diana epoxy resins provide solid, rigid, sometimes brittle materials by curing with conventional hardeners, which, when cured in conjunction with materials with different volumetric thermal expansion, have considerable internal stress, which often leads to cracking of the articles. These drawbacks are manifested mainly in its application to products of larger sizes with insufficient resistance to low temperatures, impact and the like. The use of reactive solvents usually provides slight flexibility in addition to viscosity reduction.

We have now found that some of these problems can be solved by using a reactive epoxy composition comprising by weight

100 parts epoxy resin with an average molecular weight of 360 to 600, which may contain up to 25% of the external or internal plasticizer, up to 30 parts of condensates of cycloaliphatic ketones and monoethanolamine of amine number

CS 272 822 Bl

290 to 390 mg KOH / g and from amine hardener aliphatic in an amount of 60 to 120% of the theory based on the content of reactive groups in the epoxy resin.

The condensates are prepared by reacting a cycloaliphatic ketone, for example cyclohexanone, with monoethanolamine. The resulting water is removed azeotropically, for example by cyclohexane. After distilling off the solvent, a condensate is obtained: A light reddish-brown liquid with a mild terpenic odor and slight turbidity, which disappears completely when dissolved in the epoxy resin. The amine number is in the range 290 to 390 mg KOH / g and the viscosity at 25 ° C is 14 to 24 mPa.s. The condensate is usually a complicated mixture of a number of substances with different proportions. A complete analysis has not yet been carried out. For example, starting from methyloekylohexanone, the major compound is 7-methyl-1-oxa-4-azaspiro- (4,5) decane,

The cycloaliphatic ketone condensate with monoethanolamine may be introduced into the composition as a separate component or as a solution thereof in a resin or hardener. Due to the reactivity of its secondary amine hydrogen with the epoxy group when dissolved in the resin, an increase in viscosity has to be expected (see Example 1). This increase is slow and allows use with a longer pot life.

An advantage of the present invention is the reduction in contact with the health-modifying modifying agents in the manufacture of the modifiers and reducing the contact of application personnel. Slower curing allows processing of larger volumes of epoxy resin, a significantly lower exotherm leads to very low shrinkage, and a decrease in average functionalization (geometric mean number of reactive sites of molecules in the reactive composition for a particular reaction) allows the preparation of resilient masses.

For the users of the reactive compositions, a mass mixing ratio with hardener as close as possible to 1: 1 is usually more preferred. The use of a solution of cycloaliphatic ketone condensates and monoethanolamine in amine hardeners often allows this more convenient formulation of the compositions.

The properties of the obtained materials can be influenced by the choice of the starting epoxide, polyamine, the type and quality of the cycloaliphatic ketone, the degree of hardening of the hardener, the amount of hardener relative to theory and the possible presence of other plasticizers in the resin. By changing the types and proportions of fillers, mechanical and electrical properties (strength, abrasion, surface resistance, etc.) and processability (viscosity, thixotropy) can be influenced.

The epoxy resins used are prepared by known methods, mostly by condensation of diane with epichlorohydrin in an alkaline medium. They may contain both an outer and an inner plasticizer.

The reactive epoxy compositions of the invention are generally yellow-brown liquids having a viscosity of 0.5 to 10 Pa.s. They do not smell like acrylates and can optionally be combined with each other.

The hardeners for the reactive epoxy compositions of the invention are all common aliphatic polyamines, adducts of reduced functionality, aminoamides and others such as cyclohexylaminopropylamine, xylylenediamine, N-aminoethylpiperazine, etc. They are used in an amount of 60-120% of the theory based on epoxide group content; of double bonds in an epoxy resin.

Example 1

The condensate of 2.5 M cyclohexanone (99%), 1.5 M methylcyclohexanone (83 SS) 8 4 M monoethanolamine has an amine number of 381 and a viscosity of 21 mPa · s / 25 ° C. Addition of 2, 5 and 10 g to 98, 95 and 90 g of epoxy resin having an average molecular weight of 388 and a viscosity of 15900 mPa.s reduces the viscosity to 8 640, 5 360 and 3470 mPa.s. After 10 days the viscosity increased to 23,800, 66,000 and 120,000 mPa.s. Reactive epoxy compositions of fresh modifications and dipropylene triamine in an amount of 110% of theory to epoxy groups had temperature increases in 15 minutes at 23 ° C of 10, 11 and 11.5 ° C for a weight of 160 g of the composition.

and

CS 272 822 Bl

Example 2

Condensate from 451 g of methylcyclohexanone. containing ketones of 72 wt. # 177 g monoethanolamine has an amine number of 300 mg KOH / g and a viscosity of 19.4 mPa.s. Epoxy resin with an average molecular weight of 388 and a viscosity of 15,900 mPa.s. was modified with condensate and diethylenetriamine was used as a hardener. The table shows the proportion of condensate in the resin in wt. % (P),% hardener theory against epoxy groups (D), viscosity in mPa.s / 25 ° C (V), temperature rise of 160 g reactive composition after 15 minutes at 23 ° C (N) and tensile strength ( lPa) and ductility (%} after 28 days of casting and gelation time in hours (G)

P D V ' M MPa % G 0 100 ALIGN! 15 900 9 45 6 2 2 100 ALIGN! 9 400 9 63 7.5 2 ¹ ° 3 100 ALIGN! 7 900 9.5 61 6 5 100 ALIGN! 5 560 10 56 6 ₂ T5 10 100 ALIGN! 2 790 11 60 6 15 Dec 100 ALIGN! 1 700 11 58 7 20 May 100 ALIGN! 1 250 11 55 7 25 100 ALIGN! 1 030 10 54 7 10 88.7 9 55 5.5 15- 82.1 8 53 5.5 20 May 74.6 6.5 48 6

Example 3

A reactive epoxy composition of 140 g of a 23% solution of dibutyl phthalate in a 506 average molecular weight epoxy resin, 26 g of an amine amide having a hydrogen equivalent weight of 75 and 21 g of condensate of 1 L methylcyclohexanone (83%) and 1 M monoethanolamine. mg KOH / g and a viscosity of 17 mPa.s has a temperature increase of 6 ° C after 15 minutes at 23 ° C and the mass obtained after 28 days, a tensile strength of 4.8 MPa, an elongation of 81% and a surface hardness of 75 ° Shore A.

Example 4

The condensate of 2.5 M cyclohexanone (99 95), 1.5 M methylcyclohexanone (83%) and 4 M monoethanolamine has an amine number of 381 mgKOH / g and a viscosity of 21 mPa.s. The epoxy resin with an average molecular weight of 379 and a viscosity of -1200 mPa.s was modified with 1 and 2 condensate.

P D 7 TO T 0 110 12 100 9 51 1 110 9 800 9 59 2 110 8,200 · 9 61

Example 5

A reactive epoxy composition consisting of 100 g of an average molecular weight epoxy resin of 407, 10 g of diisoctyl phthalate, 5 g of condensate of 1 .mu.l methylcyclohexanone (83 95) and 1.

5 minutes at 23 ° C temperature increase of 8 ° C and the mass obtained has a breaking strength <

CS 272 822 B1 at a thrust of 69 MPa using 11.9 g of dipropylenetriamine as a hardener (95% of theory in the epoxy groups).

Claims (1)

A low-viscosity reactive epoxy composition comprising a non-toxic reactive solvent transportable by halogenation of 100 parts by weight. epoxy resins having an average molecular weight of 360 to 600, which may contain up to 25 wt. % of the external or internal plasticizer; condensation of a cycloaliphatic ketone with a monoethanolamine having an amine number of 290 to 390 mg KOH / g and of an aliphatic amine hardener in an amount of 60 to 120% of theory based on the content of reactive groups in the epoxy resin used.