AU440570B2 - Process forthe manufacture of solvent-resistant epoxide resin coatings - Google Patents

Description

S20;39 770 Solvent-free cold-cured epoxid;e resin coatings' based on aromatic epoxide resin compounds, for example

diomethane-diglycidyl-ethers, are known and are generally

distinguished by good resistance t.o inorganic and organic

acids, alkalis,, water and some organic solvents. This

resistance can be further increased if the coatings are

subsequently heat-treated at elevated temperatures. An

improvement in the solvent resistance can: in certain cases

also be achieved by adding small amounts of aromatic hydro-

carbons, for example toluene.

The possible curing agents for curing the solvent-

free coatings based on aromatic epoxide resins are mostly

based on aliphatic polyamines, aliphatic polyamine adducts,

aromatic or cycloaliphatic-, modified amine adducts or poly-

aminoamides or polyaminoimidazo-lines..

Resistance of such coatings- especially towards

organic s.olvents is only found to a greater or lesser extent

in the case. of petrols,, higher alcohols, phthalate plasticisers

and terpene hydrocarbons, but not, for example., in the case

of ketones,, lower alcohols', chlorinated and aromatic hydro-

carbons,, glycols.or esters.

It has novw been found that coatings produced with

*compositions consisting: of special. aliphatic polyglycidyl

ethers of low viscosity and of liquid' cycloaliphatic polyamines

and/or s.olid cycloalipha-.tic polyaminesi, which at. room

temperature form. a homogeneous, liquid phase, with the special

aliphatic polyglycidyl ethers of low viscosity, as curing

agents, show a surprisingly high solvent resistance, which is

significantly greater than that of the coatings hitherto used

in practice.

20,39 7./7o The subject of the present invention is hence a

process for the manufacture of epoxide resin coatings which

are distinguished by good resistance towards organic solvents,

and in particular towards trichlorethylene, characterised

in that curable, liquid compositions of a liquid poly-

glycidyl ether or poly-(p-methylglycidyl) ether of an

aliphatic polyol, which contains at least 4 OH groups and

at least 5 carbon atoms, preferably 5 to 12 carbon atoms,

in the aliphatic hydrocarbon chain which is optionally

interrupted by oxygen atoms, and a cycloaliphatic or

cycloaliphatic-aliphatic polyamine, containing at least one

primary amino group, which forms a homogeneous, liquid phase

with the polyglycidyl ether at room temperature, are cured

at room temperature.

The polyglycidyl ethers of the following polyalcohols

have proved particularly successful for the manufacture of

highly solvent-resistant cold-curing epoxide resin coatings:

D-sorbitol, diglycerine, pentaerythritol and dipentaerythritol.

The manufacture of such polyglycidyl ethers by single-

stage or two-stage condensation of the polyalcohols with

epichlorhydrin is for example described in French Patent

Specification No. 1,097,112 and in U.S. Patent Specification

No. 2,581,464. .Above all, the polyglycidyl ethers of lower

glycols can be manufactured in good yield and quality by this

process. These known processes are less well suited to the

manufacture of the liquid glycidyl ethers of polyhydric

polyols, which are solid at room temperature, with increasing

difficulties manifesting themselves as the hydroxyl equivalence

increases and the melting point increases. A suitable process

for the manufacture of the polyglycidyl compounds indicated

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20,39 7/70 in the Table is especially the process according to Swiss

Patent Application 18312/68 (Case 6612), which describes the reaction of the polyhydroxy compound with epichlorhydrin in the presence of 1,4-dioxane.

For the manufacture of the coatings according to

the invention, those glycidylation products of the polyols

indicated are also suitable in which not all OH groups of the starting polyols are glycidylated, that is to say polyglycidyl ethers still containing minor, amounts of free OH groups.

Suitable curing agent components are liquid,

cycloaliphatic polyamines, preferably of low viscosity,

such as, for example, 3-aminomethyl-3,5,5-trimethylcyclo-

hexylamine "isophoronediamine"), bis-(3-methyl-4-amino-

cyclohexyl)-methane or N-cyclohexyl-l,3-diaminopropane.

It is however also possible to use solid, cycloaliphatio

polyamines, which at room temperature form a homogeneous

liquid phase with the polyglycidyl ethers to be used, such as, for example, 9-methyl-10-y-aminopropyldecahydro-1,8-

napthyridine or 3 ,9-bis(-y-aminopropyl)-2,4,8,10-tetroxaspiro

as curing agents.

Aliphatic polyamines are unsuitable because of their

excessively highly exothermic reaction and inadequate

resistance to water, as are polyaminoamides or polyamino- imidazolines because of their partly high intrinsic viscosity and their lower resistance to water.

The solvent-free coatings manufactured in this way are of low viscosity and are generally fully cured after hours at room temperature. The resulting films show a high surface hardness and gloss as well as medium flexibility. The films are transparent and devoid of any surface faults.

4 440570

39 7/70 If desired, known ac-celerators for the amine curing

reaction, above all phenols, lannich bases or heterocyclic

amines, such as 2,4,6-tris-(dimethylamino-methyl)-phenol,

aminoethylpiperazine or 2,2-bis-(p-hydroxylphenyl)-propane

can be added to the curable compositions, whereby the

levelling properties are also improved. Further, surface-

active substances can also be added to the.coating compositions

to reduce the surface tension.

The curable compositions, free of volatile solvents,

consisting of liquid epoxide resin and the equivalent

proportion of liquid cycloaliphatic polyamines, can also

contain further customary additives, such as fillers, pigments,

dyestuffs or liquid extenders. These pigmented paints are

distinguished by high gloss and unusually high colour shade

stability.

It is of course also possible to add proportions of

easily volatile solvents, such as for example methyl ethyl

ketone, toluene or acetone, to the epoxide resin coatings

manufactured according to the invention, without thereby

worsening the properties of the films, but no technical

advantages are gained by this measure.

The application of the coating materials manufactured

according to the invention is usually effected by brushing,

roller application or spraying onto previously cleaned

substrates, with theapplication by spraying preferably

being carried out by means of two-component instruments.

In the examples which follow, parts denote parts by

weight and percentages denote percentages by weight.

In the examples below, the following polyglycidyl

compounds, having the indicated specifications, ware used.

5 440570

2 0,39 7170 Polyglycidyl Epoxide Viscosity Cl01 content; ether equivalents/ according to saponifiable kg Hoeppler at in 250C

A D-sorbitol- 5.2 6000 cP 1.2 polyglycidyl ether 3 Diglycerine- 6.7 480 oP 0.7 polyglycidyl ether C Pentaerytl-rtol 7.2 480 oP 0.3 polyglycidyl ether D Dipenta- 5.4 9800 OP 0.8 erythritol- polyglycidyl ether

Example 1 100 parts of dipentaerythritol-polyglycidyl ether (polyglycidyl ether D) are mixed with 35 parts of bis-(3- methyl-4-aminocyclohexyl)-methane and applied to a steel substrate. The mixture shows a iisoosity, according to Hoeppler, of 2000 cP at 2500, a pot life (100 ml) of 12 hours, a dust-drying time of 3hours and complete curing -after 8 hours, in each case at 2000 and 65% relative humidity. After 7 days'curing at 200 C, the film surface shows a Persos hardness of 300 seconds. After 3 months exposure at room temperature, the films show no attack whatsoever by trichlorethylene, ethylengtyco. mcoethylether, Wban6 (95% strength), benzene, petrol or tetralin and are easily attacked on immersion in acetone or ethyl acetate.

Example 2 100 parts of pentaerythritol-polyglycidyl ether (polyglycidyl ether 0) are mixed with 46 parts of bis-(3-

6 440570

20,397/70 methyl-4-aminocyclohexyl)-methane and applied. This mixture shows a viscosity, according to Hoeppler, of 300 cP at 250C, a pot life (100 ml) of 16 hours, a dust-drying-time of 5 hours and complete curing in 10 hours. The surface hardness according to Persoz is about 250 seconds after

7 days at 20 C, and the deep drawing value according to Erichsen, DIN 53156, is 4 to 5 mm after 8 weeks at 2000. After an immersion in solvents for 3 months at room temperature, the films show no attack whatsoever trichlorethylene, ethyl acetate, ethyleneglycol mcnea-yleter, etiaol

strength), benzene, petrol, tetralin, water (distilled) and sea water. The film shows limited resistance to acetone.

Example 3 Correspondingly to example 2, 100 parts of pentaerythritol-polyglycidyl ether (polyglycidyl ether 0) are mixed with 31._parts of bis-(3-methyl-4-amino-cyclohexyl)- methane and 4 parts of 2 ,4,6-tris-(dimethylaminomethyl)-phenol and applied. Whilst the viscosity of the mixture is virtually similar, corresponding to the mixture according to example 2, the present mixture is already fully cured after 7 hours. The cured films also possess virtually the same resistance properties towards solvents, with slightly worse resistance to water. Examole 4 100 parts of D-sorbitol-polyglycidyl ether (polyglycidyl ether A) are mixed with 33 parts of bis-(3- methyl-4-aminocyclohexyl)-methane and applied to a sand- blasted steel substrate. The mixture shows a viscosity,

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2 0,39 7/70 according to Hoeppler, of 6600 cP at 2500, a pot life

(100 ml) of 2.1/4 hours, a dust-drying time of 5 hours and

complete curing after 6 hours, in each case at 200C and

relative humidity.

After 8 weeks'storage at 6000, the 200 p thick

coating shows a deep-drawing value according to Erichsen,

DIN 53156, of 5 to 6 mm.

After an immersion in solvents for 3 months at

room temperature, the films show no attack whatsoever by

benzene, petrol, tetralin and water, and are slightly

attacked by ethyl acetate, ethyleneglycol monoethylether,

ethanol (95%)-and trichlorethylene.

Example

100 parts of diglycerine-polyglycidyl ether (poly-

glycidyl ether B) are mixed with 42 parts of bis-(3-methyl-

4-aminocyclohexyl)-methane and applied to a-steel substrate.

This mixture shows a viscosity, according to Hoe.ppler, of

800 cP at 25ocQ a pot life of 2.1/4 hours and a dust-dry

time of 5 hours, and requires approx. 8 hours for complete

curing. After 7 days' curing at 200C, the coating is

distinguished by a Persoz surface hardness of 270 seconds

and after 8 weeks by a deep-drawing value, according to

Erichsen, DIN 53156, of 4 to 5 mm. After 3 months' immersion

in solvents at room temperature, the films show no attack

whatsoever by benzene, petrol and tetralin, and show limited

resistance to acetone, ethyl acetate, athyleneglycol mono-

ethylether "aid -trichlorethylene.

Example 6

100 parts of pentaerythritol-polyglycidyl ether

(polyglycidyl ether C) are mixed with 40 parts of 9-methyl-

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20,3 9 7/70 l0-y-aminopropyl-decahydro-l,8 -naphthyridine, which has been fused at 600C, and are applied. The film, cured at 2000/ relative atmospheric humidity, shows a time for complete cure of 6 hours, and a dust-dryirgti e of lOhours, at 200 a thickness. The surface hardness according to Persoz is

seconds after 1 day and 80 seconds after 7 days. The deep-drawing value according to Erichsen, DIN 53156, is mm after 7 days'curing at 2000.

Example 7 100 parts of pentaerythritol-polyglycidyl ether (polyglycidyl ether C) are mixed with 51 parts of 3,9-bis- (y-aminopropyl)-2,4,8,10-tetrbxaspiro [5.5]-undecane, which. was fused at 500C. The gel time of this mix is 65 minutes at 200C for a quantity of 100 ml. The films cured at 2000/ relative atmospheric humidity are fully cured after 3 hours and dust-dry after 6 hours. The hardness according to Persoz is 30 seconds after 1 day and 55 seconds after 7 days. The deep-drawing value according to Erichsen, DIN 53156, is 6.2 mm after 7 days' curing at 2000.

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Claims (4)

20,397/70 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. Process for the manufacture of epoxide resin

coatings which are distinguished by good resistance towards

organic solvents, characterised in that curable liquid

compositions of a liquid polyglycidyl ether or poly-

(l-methylglycidyl)-ether of an aliphatic polyol, which contains at least 4 OH groups and at least 5 carbon atoms,

in the aliphatic hydrocarbon chain, and a cycloaliphatic or cycloaliphatic-aliphatic polyamine containing at least

one primary amino group, which at room temperature forms a

homogeneous liquid phase with the polyglycidyl ether

are cured at room temperature.

2. Process according to claim 1, characterized in that

the aliphatic hydrocarbon chain of the liquid polyglycidyl

ether or poly (P-methylglycidyl)-ether of an aliphatic

polyol, has 5 to 12 carbon atoms.

3. Process according to claim 1 or 2, characterized in that the aliphatic hydrocarbon chain of the liquid poly-

glycidyl ether or poly -methylglycidyl)-ether of an aliphatic polyol, is interrupted by oxygen atoms.

2U39 7/70

4. Process according to any one of claims 1 to 3.

characterised in that a cycloaliphatic.or cycloaliphatic-

aliphatic polyamine, containing at least one primary amino

group, which is liquid at room temperature, Is used as the curing

agent component.

Process according to claim characterised in that a

composition is used which additionally also contains an organic

solvent.

6. Process according to any one of claims 1 to

characterised in that the polyglycidyl ethers of diglycerine, of

pentaerythritol, of dipentaerythritol or of D-sorbitol are used

as epoxide resin components.

7. Process according to any one of claims 1 to 4,

characterised in that bis-(3-methyl-4-aminocyclohexyl)-methane

is used as the polyamine.

8. Process according to anyone of claims 1 to 3,

characterised in that 9-methyl-l0-Y-aminopropyl-decahydro-l,8-'

naphthyridine is used as the polyamine.

9. Process according to any one of claims 1 to 3, 4 8 characterised in that 3,9-bis-(--aminopr6pyl)-2,

tetroxaspiro [5.5]-undecane is used as the polyamine.

Process according to any one of claims i to 9,

characterised in that. the composition furthermore contains. a

curing accelerator for the polyamine curin- agent.

11. Process according to any one of claims 1 to

4405 7 0

20,39 7/70 characterised in that the composition furthermore contains

inorganic or organic pigments and/or fillers.

DATED THIS 25TH DAY OF SEPTEMBER, 1970.

CIBA LIMITED

EDWD. WATERS SONS, PATENT ATTORNEYS, MELBOURNE.