CS268956B1 - Accelerating plasticizer of aliphatic amine reaction with epoxides - Google Patents

Abstract

The solution is an accelerating plasticizer for the reaction of aliphatic polyamines with 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 with a mass composition of: 1 to 35 parts 1-naphthol, 30 to 95 parts 1-naphthyl allyl ether, 2 to 30 parts 4-allyl-1-naphthol and 1 to 20 parts 2-allyl-1-naphthol.

Description

The invention relates to the acceleration of the reaction of aliphatic polyamines and epoxy resins or liquid epoxy elastomers with a naphthol solution in a mixture of allyl derivatives of naphthol with a simultaneous plasticizing 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 hardening accelerators, although the reaction of the epoxy group with hydrogen of the primary and secondary amine groups forms a secondary hydroxyl group, which also accelerates. Any acceleration of hardening is simultaneously associated with a shortening of the workability time. If a slower-reacting hardener is used, such as amine adducts or amino amines, it may be necessary to accelerate hardening 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 hardened mass and greater internal stress in it.

Hydrogen atom donors, such as alcohols, phenols, acids or water, usually have an accelerating effect. However, they usually have too low boiling points, so they cannot be used in larger quantities, or they have a higher molecular weight, but then they are solid and must be dissolved for dosing, e.g. phenol A.

In addition to its effectiveness, a practically usable accelerator must also have good processability, dosing, be compatible with resins and have no undesirable effects on the properties of the cured materials. For example, asalicylic 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 ethermonoglycidyl 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 are less effective and larger amounts need to be used. Larger amounts can be used if the accelerator has a plasticizing effect, because there is no sharp deterioration in mechanical properties in particular. The effectiveness increases with the acidity of the phenolic OH group. However, strong acids do not accelerate, they prefer to form amine salts. Sometimes pyrrolidine complexes with metals, amides, imides, nitriles, lactic acid, hydroxyalkylated polyamines, sulfamides, sulfonic acids, thiocyanic acid salts, aminopropyl derivatives of polyoxyalkylenepolyamines, condensates of aniline with formaldehyde, sulfones, derivatives of tetrahydrothiodiazine or tetrahydrothiadiazine-2-thione, aryldimethylureas, thiourea, piperazine, thiophosphates, phenol-formaldehyde condensates, tris-/dimethylaminomethyl/-phenol, triphenylphosphite, etc. are used.

We have now found that many of the above-mentioned problems with accelerating the curing of epoxy resins or liquid epoxy elastomers with aliphatic polyamines are solved by using a plasticizing accelerator composed by weight of 1 to 35 parts of 1-naphthol, 30 to 95 parts of 1-naXtylallylether· 2 to 30 parts of 4-allyl-1-naphthol and 1 to 20 parts of 2-allyl-1-naphthol. It is used in an amount of 0.5 to 35 parts per 100 parts of epoxy.

Accelerating plasticizers according to the invention are prepared by mixing the individual components (sometimes it is necessary to use elevated temperatures, e.g. 70 °C) or as products of a suitably conducted reaction of allyl chloride with naphthol. Sometimes it is appropriate to add an inert plasticizer or diluent to the accelerator for better processability.

New accelerating plasticizers are usually dark red clear liquids without a pronounced odor with a viscosity of 15 to 50 mPa.s/25 °C. Due to the higher average molecular weight, they can be used in larger quantities than the accelerators used so far. They have a significantly lower toxicological hazard for workers, are not washed out by water and reduce the viscosity of the epoxy used. Their effectiveness is comparable to m-cresol. In addition, they increase

CS 268956 81 resistance to dry heat. Acceleration and plasticization increase with the amount used. It can also be used for modified epoxy resins. When modifying esters of unsaturated organic acids, whose double bonds react additively with aliphatic polyamines, it is necessary to increase the amount of aliphatic polyamines by the corresponding dose. These include, for example, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, trimethylhexamethylenediamine, pentamethylenediamine, their adducts, modifications and mixtures. Acceleration and plasticization have been found in other polyamines. e.g. isophoronediamine. It is usually used in amounts of 90 to 160% of theory based on the content of epoxy groups.

The epoxy resins used are usually palm type with an average molecular weight of 300 to 600 and may also contain fillers, pigments and additives regulating mechanical and technological properties. Liquid epoxy elastomers tend to have an average molecular weight of 500 to 1,000. These 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 1,500.

Example 1 ·

The types of accelerating plasticizers used had the following probable composition in wt.%:

type A B C l-naphthol 30 10 1 1-Naphthyl allyl ether 40 60 89 4-allyl-l-naphthol 20 20 6 2-allyl-l-naphthol 10 10 4- viscosity, mPa.s/25 °C 36 25 18

The accelerating effect was monitored in the reaction of an epoxy resin with an average molecular weight of 394 with dipropylenetriamine at 23 °C. 140 g of resin, 2.8 g of the test substance and 18.5 g of dipropylenetriamine (100% of theory) 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 content of OH groups of the test substance in mol/100 g and the ultimate tensile strength T (MPa) and elongation t (%) determined 28 days after casting are given in the table!

test substance + °C OH T t

— 8 - 39 3 1-Naphthyl allyl ether ' 9 0.007 60 4 type A 15.5 0.371 78 7 type Θ 11 0.232 55 4 type c 10 0.061 56 4

Example 2

Compositions were prepared and cast using the procedure given in Example 1.

K (135 g of epoxy resin with an average molecular weight of 3B4 + 15 g of accelerator type A + 14.8 g of diethylenetriamine),

L (126 g of the same resin + 14 g of type A + 23 g of diethylenetriamine, i.e. 150% of theory),

M (122.4 g of the same resin ♦ 27.6 g of type A + 13.4 g of diethylenetriamine),

N (114.2 g of the same resin + 25.8 g of type A + 1B.7 g of diethylenetriamine. i.e. 150 theory) and

P (124 g epoxy resin with an average molecular weight of 573 + 31 g accelerating plasticizer type B + 9.1 g diethylenetriamine). i

The temperature increase in 5 minutes at an ambient temperature of 25 °C and the determined tensile strength and elongation after 2Θ days are given in the table:

CS 268956 Bl

composition + °C th (MPa) t (%) To 6 · 62 5 L 9 ⁵⁹ , 5 M 12 60 4 N 13 49 5 P 13 31 3

Example 3

The influence of the accelerator on the course of the formation of epoxy rubber is shown by composition R (140 g of liquid epoxy elastomer with an average molecular weight of 800 + 14 g of trimethylhexamethylenediamin + O or 2.8 g of type A). The values found are: g of accelerator ♦ °C/io minutes pressure (MPa) t (%)

About 7

2.8 10

Example 4

_Composition Q (140 g of epoxy resin with an average molecular weight of 392 + 2.8 g of accelerator + 19 g of dipropylenetriamine) was monitored at 25 °C. After 10 minutes, temperature increases were determined, and after 28 days, mechanical values - tensile strength T (MPa), elongation t (%) and tensile product (MPa.%) were determined;

accelerator °C T t product * type A « 1-naphthol 11 78 7 546 triethanolamine 11 63 6 378 trlkresol 12 77 2.5 193

Example 5

To compare the lower temperatures of the accelerating plasticizer according to the invention, compositions S (16 g of epoxy resin with an average molecular weight of 580 + 4 g of accelerator type B + 1.2 g of diethylenetriamine) and composition U (16 g of the same resin + 4 g of dibutyl phthalate + 1.2 g of diethylenetriamine) were prepared. After rapid weighing and 5-minute homogenization by stirring, the compositions were poured into a tin lid with an inner diameter of 54 mm to a height of 5 mm and placed in a warm room at +2 °C. After 21 hours, composition S was non-sticky with a surface hardness of 87 °Shore A. _Composition U was an adhesive and its surface hardness was lower than 30 °Shore A. Example 6 '

The effect of thermo-oxidative aging (4 days, 125 °C) was verified for a composition of (120 g epoxy resin with an average molecular weight of 588 + 30 g plasticizer + 8.8 g diethylenetriamine), the weight loss is given in % by weight:

plasticizer °C/10min That *0 ^T 4 ^l 4 decline dibutyl phthalate 6 37 6 9 2 3.3 benzyl alcohol 19 43 5 3 2 10.4 diallyl ether of benzene A 6 64 5 44 4 1.3 type A 12.5/5 minutes 60 4 25 2 0.35

EN 268956 81

Claims (1)

Accelerating plasticizer for the reaction of aliphatic polyamines with epoxy resins with an average molecular weight of 300 to 600 and with liquid epoxy elastomers with an average molecular weight of 500 to 1,000, characterized in that it consists by weight of 1 to 35 parts of 1-naphthol, 30 to 95 parts of 1-naphthyl allyl ether, 2 to 30 parts of 4-allyl-1-naphthol, 1 to 20 parts of 2-allyl-1-naphthol.