WO2004003050A1

WO2004003050A1 - Polyether urethane amines

Info

Publication number: WO2004003050A1
Application number: PCT/EP2003/050257
Authority: WO
Inventors: Jörg Volle; Wolfgang Scherzer
Original assignee: Huntsman Advanced Materials (Switzerland) Gmbh
Priority date: 2002-07-01
Filing date: 2003-06-25
Publication date: 2004-01-08
Also published as: TW200401789A; AU2003255520A1

Abstract

The invention relates to hydroxyl-containing polyether urethane amine as a hardener for epoxy resins, obtainable by the steps of a) reacting a polyalkylene polyether polyol with epichlorohydrin in a molar ratio of from 5:1 to 1:1, to give a hydroxyl-containing polyalkylene glycol monoglycidyl ether of the general formula (I), in which R = -H or -CH3 and n = 1 to 100, b) further linking, via the hydroxyl group of this polyalkylene glycol monoglycidyl ether of the formula (I), to a diisocyanate or polyisocyanate, to give a polyurethane epoxide, and c) subsequently forming an adduct from the polyurethane epoxide with an amine containing at least two reactive amine hydrogens per molecule, the molar ratio of polyurethane epoxide and amine being between 1:10 and 1:0.5; and to curable epoxy resin compositions comprising a polyether urethane amine of the invention; and also to the use of these curable compositions for producing shaped parts, coatings, foams.

Description

Polyether urethane amines

The invention relates to hydroxyl-containing polyether urethane amines as curing agents for epoxy resins, to a curable composition comprising these products as a formulating component, producing - in particular through the use of long-chain polyether urethane amines as hardeners for epoxy resins - elastic, chemical-resistant thermosets with low degrees of crosslinking, and also to the use of these curable compositions for producing mouldings and coatings.

Epoxy resins have long been widely used for producing corrosion protection coatings, abrasion-resistant coatings, casting compounds and adhesives which possess outstanding mechanical strength and have good chemical resistance. Owing to their high crosslinking density, amine-cured epoxy resins, particularly those based on diphenylpropane and epichlorohydrin, are hard and brittle, with glass transition ranges above 20°C.

In practice, the great hardness and high strength of amine-cured epoxy resins are not always necessary; at the same time there is frequently a desire for elastification and reduction in brittleness. For these qualities a variety of methods have been employed to date, but have not always been satisfactory.

In principle the degree of elastification can be raised internally, by lowering the crosslinking density, and externally, by adding plasticizer.

External elasticating agents are not reactive and are not incorporated into the thermoset network. They expand the network only by filling space. The external plasticizers include tar, phthalates, high-boiling alcohols, glycols, ketone resins, vinyl polymers, and similar products not reactive with epoxy resins and amine hardeners. This type of modification is suitable only for certain applications. Its contribution to elastification is minimal, since there is no substantial effect on the glass softening range but the thermoset structure is greatly disrupted. Internal elastification of epoxy resins can be achieved by reducing the functionality of the hardener, as described, for example, in DE-A 22 00 717. Customary for a long time, and to a considerable extent, have been long-chain, low- functionality amino amides based on monomeric and dimerized fatty acids. The flexibility of the thermosets based on these amino amides is too low for many applications, however.

From DE-A 10 90 803 it is also known to modify such systems by including polyurethanes.

DE-C 24 18 041 discloses a process for producing elasticated mouldings and sheetlike structures in which the hardener used includes the polyether amines described in DE-C 24 62 791 , which contain urethane groups.

These curing agents produce thermosets having good elastic properties, but in practice the relatively high viscosity of the curable compositions is found to be a hindrance. Moreover, such compounds have poor surface qualities. Good surfaces, however, are desired, particularly when such products are used as a single-layer coating.

An object was therefore to provide new, comparatively low-viscosity formulating components for curable compositions, the intention being that on the basis of their properties the formulating components should make it possible in particular to produce, inter alia, elasticated mouldings having good surface properties.

It has now surprisingly been found that this object can be achieved with specific new polyether urethane amines. The present invention also accordingly provides a hydroxyl- containing polyether urethane amine as a curing agent for epoxy resins, obtainable by the steps of a) reacting a polyalkylene polyether polyol with epichlorohydrin in a molar ratio of from 5:1 to 1 :1 , preferably 1 :1 , to give a hydroxyl-containing polyalkylene glycol monoglycidyl ether, possibly still containing free polyalkylene glycol, of the general formula (I)

in which R = -H or -CH₃ and π = 1 to 100, preferably 3 to 50, b) further linking, via the hydroxyl group of this polyalkylene glycol monoglycidyl ether of the formula (I), to a diisocyanate or polyisocyanate, to give a polyurethane epoxide, and c) subsequently forming an adduct from the polyurethane epoxide with an amine containing at least two reactive amine hydrogens per molecule, the molar ratio of polyurethane epoxide and amine being between 1 :10 and 1 :0.5, preferably 1 :1.

As amines it is possible in principle to use those which contain at least two reactive amine hydrogen atoms, examples being heterocyclic amines such as piperazine, N-aminoethylpiperazine; cycloaliphatic amines such as isophoronediamine, 1 ,2-(1 ,3;1 ,4)- diaminocyclohexane, aminopropylcyclohexylamine, tricyclododecanediamine (TCD); araliphatic amines such as xylylenediamine; aliphatic, optionally substituted amines such as ethylenediamine, propylenediamine, hexamethylenediamine, 2,2,4(2,4,4)- trimethylhexamethylenediamine, 2-methylpentamethylenediamine; ether amines such as 1 ,7-diamino-4-oxaheptane, 1 ,10-diamino-4,7-dioxadecane, 1 ,14-diamino-4,7,10- trioxatetradecane, 1 ,20-diamino-4,17-dioxaeicosane and, in particular, 1 ,12-diamino-4,9- dioxadodecane. It is also possible to use ether diamines based on propoxylated diols, triols and polyols ("Jeffamines^®" from Texaco). Furthermore it is possible to use polyalkylenepolyamines such as diethylenetriamine, triethylenetetraamine, dipropylenethamine, tripropylenetetraamine, and high molecular mass amines or adducts or condensation products containing free amine hydrogen. Preference is given to using polyethylenepolyamines such as, for example, ethylenediamine, diethylenetriamine, N-aminoethylpiperazine and cycloaliphatic amines such as, for example, isophoronediamine or aminopropylcyclohexylamine.

The isocyanates used in accordance with the invention for linking the polyalkylene glycol monoglycidyl ethers are the commercially customary aliphatic, araliphatic, cycloaliphatic or aromatic diisocyanates or polyfunctional isocyanates and also their trimerization products. Examples that can be mentioned include the following: tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, methylenedi(phenyl isocyanate), tetramethylene diisocyanate. Diisocyanates used with preference are tolylene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate. This list is not complete, but there is no need to mention that in order to link the polyalkylene glycol monoglycidyl ethers it is possible in principle to use all isocyanates having a functionality of at least 2. Through selection of the polyalkylene glycol and of the isocyanate it is possible to adjust properties, such as the elasticity, for example. Selection of shorter polyalkylene glycols, for example, leads generally to less elastic properties, or selecting longer polyalkylene glycols leads generally to more flexible properties. The hydroxyl-containing prepolymeric polyether urethanes obtained in this way are comparatively low-viscosity liquids. The adducts of the invention can be used as formulating components for curable compositions, preferably as curing agents for epoxy resins for producing elastic mouldings, coatings and foams. As curing agents the polyether urethane amines can be used alone or in a mixture with other amine hardeners customary in this field.

The present invention therefore further provides a curable composition comprising I) an epoxy resin having on average more than one epoxide group in the molecule and II) a hydroxyl-containing polyether urethane amine of the invention. The mixing ratio of I) to II) depends on the one hand on the amine equivalent of the polyether urethane amine and on the other hand on the epoxide equivalent of the epoxide compound and can amount to between 10 phr (parts per hundred parts resin I) and 1 000 phr. In order to adjust certain properties, however, the polyether urethane amine II) can also be used in an amount deviating from the theoretical mixing ratio, and also in a substoichiometric or superstoichiometric amount relative to the epoxy resin.

Not only the hydroxyl-containing polyether urethane amines of the invention themselves but also the curable compositions surprisingly possess a much lower viscosity than the known amino amides and the curable compositions prepared from them. Moreover, the surfaces obtained after curing of the curable compositions of the invention feature low levels of structuring and hydrate formation and a low level of development of a greasy film.

The curable compositions may further comprise the additives that are customary in epoxy resin technology and also other curing agents, especially aminic curing agents. Examples of customary amine hardeners are: aliphatic amines, e.g. polyethylenepolyamines and polypropylenepolyamines, for example diethylenetriamine and dipropylenetriamine, 2,4,4(2, 2,4)-trimethylhexamethylenediamine; cycloaliphatic diamines, such as 1-amino-3- aminomethyl-3,5,5-trimethylcyclohexane, also called isophoronediamine, and 3,3'-dimethyl- 4,4'-diaminodicyclohexylmethane; heterocyclic amines, such as piperazine; long-chain polyether amines, such as 1 ,12-diamino-4,8-dioxadodecane; aromatic amines, such as phenylenediamine, diaminodiphenylmethane; polyamido amines formed from natural or synthetic fatty acids and polyamines; amine adducts; and phenol-aldehyde-amine condensates. The hydroxyl-containing polyether urethane amines of the invention can be formulated in a known way with further formulating components such as viscosity regulators, accelerators - such as tertiary amines, triphenyl phosphite, alkylphenols - or with rapid hardeners, such as Mannich bases.

The epoxy resins I) used are curable hot and cold with the hardeners or hardener mixtures of the invention. They contain on average more than one epoxide group per molecule and can be glycidyl ethers of monohydric or polyhydric alcohols, such as glycerol, hydrogenated diphenylolpropane, or of polyhydric phenols, such as resorcinol, diphenylolpropane or phenol-aldehyde condensation products. It is also possible to use the glycidyl esters of polybasic carboxylic acids, such as hexahydrophthalic acid or dimerized fatty acids.

Particular preference is given to using liquid epoxy resins based on epichlorohydrin and diphenylolpropane having epoxide values of 0.4 - 0.6 epoxide groups/100 g resin.

If desired it is also possible to use, as reactive diluents, monofunctional aliphatic and aromatic glycidyl ethers, such as butyl glycidyl ether, phenyl glycidyl ether, or glycidyl esters, such as glycidyl acrylate, or epoxides, such as styrene oxide, or polyfunctional diglycidyl or thglycidyl ethers, particularly those of low molecular mass.

The combination of the long-chain polyether urethane amines having low degrees of crosslinking with highly crosslinking amine formulations makes it possible within a wide range to adjust the properties of the reactive resin composition in respect of viscosity, reactivity and the like and the properties of the thermoset in respect of elasticity, crosslinking density, mechanical strength and chemical resistance.

For the formulation of a reactive resin composition for coating, adhesive bonding or casting, the customary fillers, both mineral-based and organic-based, pigments, plasticizers, accelerators, solvents and other adjuvants are suitable. For the production of foams it is possible to use the blowing agents customary in this field, particularly the silane compounds which give off hydrogen.

The compositions of the invention can be employed with particular advantage where there is a need for effective substrate adhesion, good chemical resistance and elasticity for the bridging of cracks in the substrate and for the reduction of internal stress, including applications where these qualities are required at relatively low temperatures. One important field of use, therefore, is exemplified by the crack-bridging coating of concrete, for example, for industrial floors or impermeable safety basins, for heating oil tanks for example. Owing to their outstanding adhesion to iron and concrete and the adjustable elasticity the compositions of the invention are additionally suitable as casting compounds for joints, adhesives and liquid-tight, crack-bridging membranes. The low-shrink and low-stress curing also allows the production of large-sized mouldings or shaped parts.

The present invention further provides a process for producing shaped parts, coatings and foams, characterized in that the shaped parts are produced using a curable composition of the invention.

The present invention further provides a cured product obtainable by curing a composition of the invention.

Example 1 : Preparation of the reactants: A) Polyalkylene glycol monoglycidyl ethers

A1) From 2 000 g of polypropylene glycol (molar weight 2 000, OH number: 56) (1 mol) and 92.5 g of epichlorohydrin (1 mol) a known method - addition reaction in the presence of boron trifluo de etherate and ring closure in the presence of aqueous sodium hydroxide solution - produces approximately 2 070 g of a polypropylene glycol monoglycidyl ether having the following characteristics: epoxide value: 0.042 epoxide group/100 g resin; chlorine content (ASTM): 0.1 %; viscosity/25°C: 400 mPa.s with Rotovisko^® (beaker apparatus), measured according to the manufacturer's specifications; hydroxyl number: 26.

A2) In analogy to Example A1 ) a polyethylene glycol monoglycidyl ether is prepared from polyethylene glycol (molar weight 1 065) (1 mol) and 92.5 g of epichlorohydrin (1 mol): epoxide value: 0.08 epoxide group/100 g resin; chlorine content in % (ASTM): 0.1 ; viscosity/25°C: lardy-solid; hydroxyl number: 49.

A3) In analogy to Example A1 ) a difunctional glycidyl ether is prepared from a glycerol/propylene oxide adduct (molar weight approximately 1 500) (1 mol) and 185 g of epichlorohydrin (2 mol): epoxide value: 0.10 epoxide group/100 g resin; chlorine content (ASTM): 0.1%; viscosity/25°C: 170 mPa.s; hydroxyl number: 34. B) Preparation of the polyether urethane epoxides

B1 ) A reaction vessel is charged under nitrogen with 2 157 g of the polyalkylene glycol monoglycidyl ether (=1 hydroxyl equivalent) A1 and 0.2 g of dibutyltin laurate. At approximately 60°C 111 g of isophorone diisocyanate (1 isocyanate equivalent) are added continuously over the course of approximately 15 minutes. The mixture is subsequently stirred for 30 minutes until reaction is complete. The product has an epoxide value of 0.041 mol epoxide per 100 g.

C) Preparation of the polyether urethane amines

C1 ) A reaction vessel is charged under nitrogen with 2380 g (1 epoxide equivalent) of the polyether urethane epoxide prepared under B1) and at room temperature 129 g (1 mol) of N-aminoethylpiperazine (NAEP) are metered in over the course of one hour. Following the addition of NAEP the mixture is heated to an internal temperature of 100°C over the course of 30 minutes. It is subsequently stirred at 100^CC for 30 minutes until reaction is complete. The resulting hydroxyl-containing polyether urethane amine has the following characteristics: amine number: (mg KOH/g substance): 45; Gardner colour number: 1-2; viscosity: 3.0 Pa.s.

In analogy to the above examples the adducts listed in Table 1 below are prepared.

Key:

1 PAGMGE Polyalkylene glycol monoglycidyl ether

2 IPDI Isophorone diisocyanate

TDI Tolylene diisocyanate

TMDI Tetramethylene diisocyanate

MDI Methylenedi(phenyl isocyanate)

HMDI Hexamethylene diisocyanate

3 NAEP N-Aminoethylpiperazine

ED 350 Amino amide from monomeric fatty acid

XDA Xylylenediamine

DETA Diethylenetriamine

D 230 Polyoxypropylenediamine (Texaco)

TMD Trimethylhexamethylenediamine

4 V Viscosity at 25°C in Pa-s

Application examples

Example 13: Example of a liquid-tight, crack-bridging membrane.

51.75 kg of polyether urethane amine from Example 1 , 9.14 kg of trimethylhexamethylenediamine (isomer mixture), 9.14 kg of coconut fatty amine, 26.73 kg of nonylphenol and 3.25 kg of 2,4,4-tris(dimethylaminomethyl)phenol are mixed with one another and the mixture is subsequently stirred intensively with 82 kg of a mixture of 86% of a diane resin (bisphenol A) having an epoxide value of 0.52 epoxide group/100 g resin and 14% of a long- chain monofunctional reactive diluent based on C₁₂/C₁₄ fatty alcohol having an Ep value of 0.33. The mixture is spread over the area of concrete for coating in a coat thickness of approximately 3 mm. The processing time for industry-standard containers of approximately 25 kg is approximately 30 minutes at room temperature.

After about 24 hours at room temperature the membrane is ready for use and after 7 days at room temperature the following physical values are measured: tensile strength: 7.2 N/mm² (DIN 54455); tear propagation resistance: 16.0 N/mm² (DIN 54455); elongation: 98% (DIN 53507).

After additional thermal ageing at 80°C for 7 days the following values are measured after cooling to room temperature (23°C/24 hours): tensile strength: 6.8 N/mm²; tear propagation resistance: 15.5 N/mm²; elongation: 115%. At -10°C the following values are measured: tensile strength: 28.0 N/mm²; tear propagation resistance: 28.7 N/mm²; elongation: 32%. Example 14 Example of a liquid-tight, crack-bridging membrane.

67.30 kg of polyether urethane amine from Example 3, 5.69 kg of trimethylhexamethylene- diamine (isomer mixture), 5 69 kg of coconut fatty amine, 16 63 kg of nonylphenol and 4.70 kg of 2,4,5-tris(dιmethylamιnomethyl)phenol are mixed with one another and the mixture is subsequently stirred intensively with 82 kg of a mixture of 86% of a diane resin (bisphenol A) having an epoxide value of 0.52 epoxide group/100 g resin and 14% of a long- chain monofunctional reactive diluent based on Cι₂/C₁₄ fatty alcohol having an Ep value of 0 33.

The mixture is spread over the area of concrete for coating in a coat thickness of approximately 3 mm The processing time for industry-standard containers of approximately

25 kg is approximately 40 minutes at room temperature

After about 24 hours at room temperature the membrane is ready for use and after 7 days at room temperature the following physical values are measured- tensile strength: 12.4 N/mm²

(DIN 54455); tear propagation resistance: 9.2 N/mm² (DIN 54455), elongation- 59% (DIN

53507)

After additional thermal ageing at 80°C for 7 days the following values are measured after cooling to room temperature (23°C/24 hours) tensile strength 7 9 N/mm², tear propagation resistance- 11 4 N/mm²; elongation- 52%

At -10°C the following values are measured, tensile strength. 18.9 N/mm², tear propagation resistance- 15.4 N/mm²; elongation- 42%.

Starting from the abovementioned binder formulations it is also possible to produce filled elastic floor coatings, casting compounds and elasticized adhesives and also elastic epoxy resin/hardener foams

Claims

1. Hydroxyl-containing polyether urethane amine as a hardener for epoxy resins, obtainable by the steps of a) reacting a polyalkylene polyether polyol with epichlorohydrin in a molar ratio of from 5:1 to 1 :1 , to give a hydroxyl-containing polyalkylene glycol monoglycidyl ether of the general formula (I)

in which R = -H or -CH₃ and n = 1 to 100, b) further linking, via the hydroxyl group of this polyalkylene glycol monoglycidyl ether of the formula (I), to a diisocyanate or polyisocyanate, to give a polyurethane epoxide, and c) subsequently forming an adduct from the polyurethane epoxide with an amine containing at least two reactive amine hydrogens per molecule, the molar ratio of polyurethane epoxide and amine being between 1 :10 and 1 :0.5.

2. Hydroxyl-containing polyether urethane amine according to Claim 1 , characterized in that the chosen molar ratio in step a) of polyalkylene polyether polyol to epichlorohydrin and in step c) of polyurethane epoxide and amine is in each case 1 :1.

3. Hydroxyl-containing polyether urethane amine according to one of Claims 1 and 2, wherein for the compound of the general formula (I) n = 3 to 50.

4. Hydroxyl-containing polyether urethane amine according to one of Claims 1 to 3, wherein for the compound of the formula (I) R = -CH₃.

5. Hydroxyl-containing polyether urethane amine according to one of Claims 1 to 4, characterized in that the isocyanate for preparing the polyether urethane epoxide is selected from isophorone diisocyanate, hexamethylene diisocyanate and tolylene diisocyanate.

6. Hydroxyl-containing polyether urethane amine according to one of Claims 1 to 5, characterized in that the amine compound for forming an adduct from the polyether urethane epoxide is a polyethylenepolyamine, a cycloaliphatic amine or an amino amide.

7. A curable composition comprising I) an epoxy resin having on average more than one epoxide group in the molecule, and II) a polyether urethane amine according to one of Claims 1 to 6 as hardener for the epoxy resin, and, optionally, fillers of a mineral or organic basis, pigments, plasticizers, accelerators, solvents, blowing agents and/or other customary hardeners.

8. Curable composition according to Claim 7, wherein the epoxy resin I) is a liquid epoxy resin based on epichlorohydrin and diphenylolpropane.

9. Cured product obtainable by curing a composition according to one of Claims 7 and 8.

10. Use of a curable composition according to one of Claims 7 or 8 for producing shaped parts, coatings, foams.