CS268955B1 - Accelerating plasticizer reaction of aliphatic amines with epoxides - Google Patents

Abstract

The solution is a plasticizer that accelerates the reaction of aliphatic amines and their adducts and modifications and epoxides while significantly reducing the viscosity and plasticization of cured materials. Accelerating plasticizers can be prepared by the reaction of 1 mole of biphenol A, 0.5 to 4 moles of phenol compound, 2 to 6 moles of allyl chloride and 2.5 to 7 moles of NaOH or KOH.

Description

The invention relates to a plasticizer accelerating the reaction of aliphatic amines and epoxides or liquid epoxy elastomers with a solution of bisphenol A and phenolic compounds in allyl derivatives of bisphenol A and phenolic compounds from the simultaneous plasticizing and diluting effect.

For successful curing of epoxy resins with aliphatic polyamines, it is recommended to work at a minimum temperature of 18 °C. At lower temperatures, it is necessary to use curing accelerators, although the reaction of the epoxy group with the hydrogen of the primary and secondary amine groups forms a secondary hydroxyl group, which also accelerates. Any acceleration of curing is simultaneously associated with a shortening of the workability time. If a slower-reacting hardener such as amine adducts or amino amides is used, it may be necessary to accelerate curing even at laboratory temperature. This causes a higher molecular weight and a lower concentration of primary amine groups. Excessive acceleration can lead to inhomogeneity of the cured mass and increased internal stress in it.

The accelerating effect is mostly exerted by hydrogen donors, such as alcohols, phenols, acids or water. However, they usually have too low boiling points and therefore cannot be used in large quantities or they have a higher molecular weight, but then they are solid and must be dissolved for dosing, e.g. Bisphenol A.

A practically usable accelerator must, in addition to its effectiveness, also have good processability, dosing, be compatible with resins and have no undesirable effects on the properties of the cured materials. For example, salicylic acid requires the absence of iron. For curing with aliphatic polyamines at laboratory temperature, the usual accelerators are triethanolamine, benzoic and salicylic acid and cresol. _Phenols are effective even at ♦5 °C, alcohols are not. Bisphenol A, which is one of the two main raw materials for the production of epoxy resins, is also effective. However, it is a solid at laboratory temperature. Acceleration by the influence of mono-2,3-dihydroxypropyl ether-monoglycidyl ether of bisphenol A, which can be obtained by hydrolysis of bisphenol A bisglycidyl ether in an alkaline environment, has also been described. Of all the phenols, m-cresol has received the most attention, but it has an unpleasant odor and is washed out with water. Alkylphenols are better in this respect, but they have lower efficiency and need to be used in larger quantities. Larger quantities can be used if the accelerator has a plasticizing effect, because there is no sharp deterioration in mechanical properties in particular. The efficiency increases with the acidity of the phenolic OH group. However, strong acids do not accelerate, they prefer to form amine salts. Sometimes pyrrolidine complexes and metals, amides, imides, nitriles, lactic acid, hydroxyalkylated polyamines, sulfamides, sulfonic acids, salts of thiocyanic acid, aminopropyl derivatives of polyoxyalkylenepolyamines, condensates of aniline with formaldehyde, sultones, derivatives of tetrahydrothiodiazine or tetrahydrothiadiazine-2-thione, aryldimethylureas, thiourea, piperazine, thiophosphates, phenol-formaldehyde condensates, tris-/dimethylaminomethyl/-phenol, triphenylphosphite, etc. are used.

It has now been found that a number of the above-mentioned problems with accelerating the curing of epoxy resins or liquid epoxy elastomers with aliphatic polyamines while simultaneously significantly reducing viscosity and slightly plasticizing are solved by using low-viscosity aromatic modifiers prepared by reacting 1 mole of bisphenol A, 0.5 to 4 moles of a phenolic compound, 2 to 6 moles of allyl chloride and 2.5 to 7 moles of NaOH or KOH in 100 parts of the above-mentioned modifiers in an amount of 0.5 to 35 parts per 100 parts of epoxy.

The main benefit is the simultaneous thinning, plasticizing and accelerating effect. Low viscosity is especially needed for work at lower temperatures and for possible filling of the system.

CS 268955 Bl □as blsphenols, blsphenol A is mainly used, but blsphenol F, etc. can also be used.

New accelerating plasticizers are usually yellow to brown liquids with a viscosity of 15 to 60 mPa.s/25 °C, they are odorless, do not release bisphenols, have significantly lower toxicological hazards for workers and very effectively reduce the viscosity of the used epoxy resin or liquid epoxy elastomer. They slightly increase the resistance to thermo-oxidative aging. They can also be used for modified epoxy resins.

Aliphatic polyamines are diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, trimethylhexamethylenediamine, pentamethylenediamine, their adducts and mixtures of modifications. Acceleration and plasticization have been found in other polyamines, e.g. isophoronediamine. '

The epoxy resins used are usually palm type with an average molecular weight of 300 to 600 and may contain fillers, pigments and additives regulating mechanical and technological properties. Liquid epoxy elastomers have an average molecular weight of 500 to 1000. They are products based on epoxy resins or compounds with an average molecular weight of 170 to 500 and polymeric fatty acids or carboxylic oligomers with an average molecular weight of 500 to 1500.

It can also be based on a mixture of 2 or more bisphenols or phenolic compounds.

For the dissolution of bisphenol A in allyl derivatives, it is advantageous to use the warm deethylation residue in their production. Polyamines are usually used in an amount of 90 to 160% of theory based on the content of epoxy groups.

Example 1

Six types of accelerating plasticizers were used, which were obtained by the reaction of moles of viscosity mPa.s/25 °C

1 bisphenol A + 2 phenol + 5 allyl chloride + 4.5 KOH type a 37 1 3 6 5.0 and 21 1 2 butylphenol 5 4.0 c 39 1 -- 2 cresol 5 4.5 D 29 1 1 resorcinol 5 ·*- 4.5 E 1827 1 -·- 2 chlorophenol 5 4.5 F 27

The accelerating effect was observed in the reaction of an epoxy resin with an average molecular weight of 397 with dipropylenetriamine at 23 °C. 140 g of resin, 2.8 g of the test substance and 19 g (100% of theory) of dipropylenetriamine were gradually weighed into a PVC crucible. Immediately after weighing, the mixture was homogenized by stirring on a 5 cm high wooden base. The temperature was read with a thermometer with a division of 1 °C. The temperature increase in 15 minutes, the tensile strength (MPa) and elongation (%) after 28 days after casting (T,t) and after 96 hours at 125 °C (14.14) and the weight loss ú (wt. %) after dry heat stress are given in Table t

type * °C T t ^{T4 4} ύ A 10 71 6.5 33 2 0.14 and 11 49 4.1 29 3 0.06 c 9.5 57 5.5 ³ 5 2.5 0.17 0 15 77 7 16 2.5 0.26 E 21 61 5 20 3 0.25 F 13 40 4 18 2.5 0.19 without and 35 3 28 2.7 0.31

CS 268955 Bl

Example 2

The effect of the amount of accelerator type A was investigated in modifications of epoxy resin with an average molecular weight of 392. The hardener was diethylenetriamine in an amount corresponding to 100% of theory relative to the content of epoxy groups in the embodiment As in Example 1. The last line states the use of 160% of theory hardener:

type A, % wt. ♦ °C/15 mln T t T ₄ t ₄ viscosity loss comp.mPa.s/25 °C

0 8 35 3 28 2.7 0.31 13400 2 10 71 6.5 33 2 0.14 10500 5 11 43 4 42 3.5 0.35 5560 20 17 65 7 61 5 1.27 1140 5 11 4x 8 40 4 0.41

Example 3 -

Homogenization of 160 g of epoxy resin with an average molecular weight of 588 and 40 g of accelerator type A gives a composition with a viscosity of 37 Pa.s/25 °C. When curing 165 g of the composition with 9.8 g of diethylenetriamine, a temperature increase of 18 °C was found in 15 minutes, a tensile strength of 57 MPa and an elongation of 6.1%. After dry heat stress (4 days, 125 °C) the strength was 41 MPa, the elongation was 3.5% and the weight loss was 1.83%.

Example 4

The influence of the accelerator on the course of the formation of epoxy rubber is shown by composition K (140 g of liquid epoxy elastomer with an average molecular weight of 800 * 14 g of trimethylhexamethylenediamine + O or 2.8 g of accelerator type F). The values found are:

g accelerator + °C/10 T (MPa) t (%)

About 7 3.0 60

2.8 10 3.2 64

Example 5

Compositions Z (150 g of epoxy resin with an average molecular weight of 385 ♦ 16.4 g of diethylenetriamine), Z1 (22.5 g of accelerator type A ♦ 127.5 g of the same resin, ♦ 13.5 g of diethylenetriamine), Z2 (22.5 g of accelerator type E + 127.5 g of the same resin ♦ 13.5 g of diethylenetriamine) and Z3 (10 g of accelerator type B ♦ 12.5 g of accelerator type F + 127.5 g of the same resin + 13.5 g of diethylenetriamine) were prepared from raw materials

rooms heated to 12 ⁰ with a temperature of 3, C and after 5 minutes 10 and 23 °C. mixing at temperature 23 °C were inserted into The gelation times found in minutes the table shows: °C 23 10 3 From 24 240 more than 8 hours From 1 19 195 360 Of 2 9 85 190 Out of 3 15 170 230 Example 6 The procedure described in example 1 it was compared speed up type A effect with its

by enrichment with 2% by weight of bisphenol A. While type A itself has a temperature increase of 10 °C in 15 minutes, the enriched one has 13 °C. The mechanical properties are the same.

Claims (1)

SUBJECT OF THE INVENTION Accelerating plasticizer for the reaction of aliphatic polyamines and epoxy resins with an average molecular weight of 300 to 600 and with liquid epoxy elastomers with an average molecular weight of 500 to 1000, which simultaneously significantly reduces viscosity and moderately plasticizes the cured mass, which can be prepared by the reaction of 1 mole of phenol A, 0.5 to 4 moles of a phenolic compound, 2 to 6 moles of allyl chloride and 2.5 to 7 moles of NaOH or KOH.