WO2004003048A1

WO2004003048A1 - Isocyanato-containing polyether urethane monoepoxides

Info

Publication number: WO2004003048A1
Application number: PCT/EP2003/050258
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: TW200403298A; AU2003255521A1

Abstract

Curable compositions comprising A) a non-C) epoxy resin having on average more than one epoxide group per molecule, B) an amine compound, C) an isocyanato-containing polyether urethane monoepoxide of the general formula (I), in which R1 and R2 independently of one another are a radical -H or -CH3, n = 0 - 50, and R3 is an aliphatic, araliphatic, aromatic or cycloaliphatic alkylene radical, it being possible for C) to be present both as a constituent in the epoxy resin A) and as an amine adduct in the amine compound B), and D) auxiliaries and additives and/or diluents, and also polyurethane systems further comprising E) an optionally blocked isocyanate, and optionally F) a hydroxy compound having on average at least two hydroxyl groups in the molecule, the use of these curable compositions as casting resin, matrix resin, tooling resin or as coating materials, and further as a formulating component for epoxy resin compositions, in polyurethane systems, and for preparing stable aqueous epoxy resin dispersions.

Description

Isocyanato-containing polyether urethane monoepoxides

The invention provides for the use of isocyanato-containing polyether urethane monoepoxides in curable epoxy resin compositions, in polyurethane systems, and for preparing stable aqueous dispersions.

Curable mixtures based on aminic hardeners and epoxy resins are widely used in industry for the coating and hardening of metallic and mineral substrates. Aminic hardeners used are, in particular, aliphatic, cycloaliphatic or aromatic amines and also polyaminoamides which if desired contain imidazoline groups.

The mechanical and physical properties of the curable mixtures based on these amines are sufficient for many applications.

Particularly for the coating sector, however, binder systems are required which are surface tolerant, i.e. which exhibit good adhesion even to substrates that are difficult to coat, such as moist substrates or unpretreated metal panels, for example, and ensure optimum protection of the substrate, e.g. corrosion protection. In the adhesive sector as well there is a demand for high adhesion to the substrates that are to be bonded.

As hardeners for epoxy resins which have a relatively good adhesion, polyaminoamides which normally contain imidazoline groups are known.

The disadvantage of these compounds is the high viscosity at low temperatures (<15°C) and the slow rate of initial curing and through-curing. Moreover compounds of this kind have relatively high colour numbers.

It was therefore an object of the present invention to eliminate these disadvantages.

This object is-achieved by the inventive use of isocyanato-containing polyether urethane monoepoxides. Surprisingly it has been found that the isocyanato-containing polyether urethane monoepoxides of the invention have outstanding adhesion in combination with a low viscosity and a low colour number. The isocyanato-containing polyether urethane monoepoxides of the invention are appropriately added to the epoxy resin as a formulating component. Alternatively they can be used as an adducting component for the epoxy resin hardener. Furthermore it has surprisingly been found that the isocyanato-containing polyether urethane monoepoxides of the invention are outstandingly suitable for preparing stable aqueous epoxy resin dispersions. Moreover the products of the invention are surprisingly and advantageously also suitable for use as a formulating constituent and for dilution in polyurethane systems.

The invention accordingly provides for the use of isocyanato-containing polyether urethane monoepoxides of the general formula (I):

in which Ri and R₂ independently of one another are a radical -H or -CH₃, n = 0 - 50, preferably n = 5 - 35, and R₃ is an aliphatic, araliphatic, aromatic or cycloaliphatic alkylene radical, as a formulating component for epoxy resin compositions and also for preparing stable aqueous epoxy resin dispersions and also in polyurethane systems.

The compounds of the general formula (I) are obtainable by reacting polyalkylene glycols, where appropriate in the presence of catalysts, with epichlorohydrin and subsequently treating the products with sodium hydroxide solution, the molar ratio of polyalkylene glycol to epichlorohydrin being from 1 :0.8 to 1 :1.2, preferably 1 :1 , and further reacting these polyalkylene glycol monoglycidyl ethers with di- or polyisocyanates, preferably diisocyanates, using 1 mol of the di- or polyisocyanate per (remaining) hydroxyl group of the polyalkylene glycol monoglycidyl ether.

As polyalkylene glycols for preparing the compounds of the invention it is preferred to use polypropylene glycols. For the preparation of the polyether urethane monoepoxides of the general formula (I) according to the invention it is possible optionally to use diisocyanates and/or polyisocyanates. Appropriately, however, only diisocyanates are used, since they lead to much less viscous products than is the case when polyisocyanates are used.

The diisocyanates used preferably in accordance with the invention for reacting the polyalkylene glycol monoglycidyl ethers are the commercially customary aliphatic, araliphatic, cycloaliphatic or aromatic diisocyanates.

Examples which may be mentioned include the following: tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, methylene di(phenyl isocyanate), tetramethylene diisocyanate.

This list is not complete, but there is no need to mention that in principle all difunctional isocyanates can be used for the preparation of the compounds of the invention.

Preference is given to using tolylene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate. Particular preference is given to isophorone diisocyanate.

The preparation of the compounds of the invention is described in the experimental section.

The isocyanato-containing polyether urethane monoepoxides of the invention can be used as mentioned at the outset as an adducting component for the epoxy resin hardener.

The invention therefore further provides adducts of the polyether urethane monoepoxides of the invention with amine compounds. The degree of adducting is chosen such that the resulting adducts still contain free amine hydrogens. Appropriately the molar ratio of amine to a compound of the formula (I) is from 10:1 to 1 :1. The molar ratio is preferably from 3:1 to 2:1.

As the amine compound it is possible to use all amines which have at least two amine groups per molecule, such as polyethylene polyamines, for example, such as diethylene- triamine, triethylenetetramine, tetraethylenepentamine, etc.; polypropylenepolyamines such as dipropylenetriamine, tripropylenetetramine, and the polyamines obtained by cyanoethylation of polyamines, especially of ethylene diamine, and subsequent complete or partial hydrogenation; aliphatic amines such as diaminoethane, diaminopropane, neopentanediamine, diaminobutane, hexamethylenediamine, 2,2,4(2,4,4)- trimethylhexamethylene-1 ,6-diamine; cycloaliphatic polyamines such as isophoronediamine, diaminocyclohexane, norbornanediamine, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.l.0]decane (TCD diamine), 1 ,3 bis(aminomethyl)cyclohexane, bis(aminomethylcyclohexyl)methane; heterocyclic polyamines such as N-aminoethylpiperazine, 1 ,4-bis(aminopropyl)piperazine; aromatic amines, such as diaminodiphenylmethane for example; optionally imidazoline- containing polyaminoamides, such as condensation products of monomeric or dimeric fatty acids with polyethylenepolyamines, for example.

As the amine component it is preferred to use isophoronediamine, xylylenediamine and bis(aminomethylcyclohexyl)methane and 2,2,4(2,4,4)-trimethylhexamethylene-1 ,6 diamine. The adducts of the invention are prepared by processes known per se, by adding a polyalkylene glycol monoglycidyl ether of the general formula (I) dropwise to the amine compound, introduced as an initial charge, at 50°C - 200°C, preferably at 60 - 80 °C, and stirring the mixture at the same temperature for about 1 hour until reaction is complete.

The level of adducting depends on the intended application and on the desired viscosity of the amine adduct. However, after the reaction with the polyalkylene glycol monoglycidyl ether, there must be at least two amine hydrogens per molecule.

The invention further provides curable compositions comprising

A) a non-C) epoxy resin having on average more than one epoxide group per molecule,

B) an amine compound as hardener for components A) and C),

C) an isocyanato-containing polyether urethane monoepoxide of the general formula (I),

in which R₁ and R₂ independently of one another are a radical -H or -CH₃, n = 0 - 50, preferably n = 5 - 35, and R₃ is an aliphatic, araliphatic, aromatic or cycloaliphatic alkylene radical, and optionally D) auxiliaries and additives and/or diluents.

The proportion of the inventive component C) to be used appropriately can vary within wide limits depending on the field of use. An inventive compound of the general formula (I) can also, however, be used as sole epoxy resin component. The amounts of A) to C) used are guided on the one hand by the epoxide equivalent of the epoxide compound A) and the epoxide equivalent and isocyanate equivalent of the compound C) and also by the active amine equivalent of the amine compound B). Good results are generally obtained when the sum of the epoxide equivalents and isocyanate equivalents of A) and C) are equal in value to the active amine equivalents B). In order to achieve certain properties, however, it is also possible to operate with a superstoichiometric or else with a substoϊchiometric amount of the amine component B).

Using the compounds of the invention it is also possible to prepare stable solid-resin dispersions, specifically by reacting the isocyanate groups of the polyether urethane epoxides with the hydroxyl groups of the solid resin and then dissolving the resultant reaction product in water, where appropriate with the use of small amounts of solubilizer. An example of a solid-resin dispersion of this kind is described in the experimental section.

The isocyanato-containing polyether urethane monoepoxides of the invention can also be used with advantage in polyurethane systems. The tensile strength and elongation at break of the mouldings produced using the compounds of the invention is comparatively high and the viscosity of the curable mixture is comparatively low.

This invention accordingly further provides curable compositions comprising:

B) an amine compound,

in which R] and R₂ independently of one another are a radical -H or -CH_3, n = 0 - 50, preferably n = 5 - 35, and R₃ is an aliphatic, araliphatic, aromatic or cycloaliphatic alkylene radical, and

D) optionally auxiliaries and additives and/or diluents, and

E) an optionally blocked isocyanate, and

F) optionally a hydroxyl compound having on average at least two hydroxyl groups in the molecule. The sum of the epoxide equivalents of A) and C) and of the active amine equivalents B) and also the isocyanate equivalents from E) and of the hydroxyl equivalents F) ought appropriately to be equal in value. Here again, however, it is possible to deviate from equivalency in order to obtain particular properties.

Where a compound C) of formula (I) according to the invention is used as an amine adduct, the appropriate molar ratio of amine to a compound of the formula (I) is from 10:1 to 1 :1. The molar ratio is preferably 2:1.

As isocyanate component E) it is possible in principle to use the isocyanates which are also used for preparing the isocyanato-containing polyether urethane epoxides and have been described there. As blocked isocyanates it is possible to use the products available commercially, which are sold, for example, under the trade mark Desmocap by Bayer. The fraction of component E) should be not more than 40% by weight, based on the total amount of components A) to F) of the composition.

The hydroxyl compounds F), which can be used as well where appropriate, are compounds having on average at least two hydroxyl groups in the molecule. Examples are ethylene glycol, propylene glycol, butanediol, glycerol, and polyalkylene glycols. Preference here is given to using polyalkylene glycols, especially polypropylene glycols. The fraction of component F) ought appropriately to be such that the number of hydroxyl groups is equivalent to the total number of the isocyanate groups of the two components C) and E).

As auxiliaries and additives D) it is possible, furthermore, to use the customary fillers such as gravels, sands, silicates, graphite, silicon dioxide, talc, mica etc. in the particle size distributions customary in this field, and also pigments, dyes, stabilizers, levelling agents, plastifiers, nonreactive extender resins, plasticizers. As diluents it is possible to use both compounds which substantially remain in the thermoset after curing, such as high-boiling alcohols and ethers such as benzyl alcohol, propylene glycol, butyl diglycol, etc., and compounds which predominantly evaporate from the coating in the course of curing, such as xylene, butanol, methoxypropanol and water, for example. Preference is given to using benzyl alcohol and water.

The epoxide compounds A) used in accordance with the invention are commercially customary products having on average more than one epoxide group per molecule which derive from monovalent and/or polyvalent and/or polycyclic phenols, especially bisphenols and also novolacs, such as bisphenol A diglycidyl ether and bisphenol F diglycidyl ether, for example. An extensive listing of these epoxide compounds can be found in the handbook "Epoxidverbindungen und Epoxidharze" by A.M. Paquin, Springer Verlag Berlin, 1958, chapter IV, and also in Lee & Neville, "Handbook of Epoxy Resins", 1967, Chapter 2. It is also possible to use mixtures of two or more epoxide compounds A). Preferred in accordance with the invention are mixtures of glycidyl ethers based on bisphenol A, bisphenol F or novolacs with what are termed reactive diluents, such as, for example, monoglycidyl ethers of phenols or glycidyl ethers based on monohydric or polyhydric aliphatic or cycloaliphatic alcohols. Examples of such reactive diluents are phenyl glycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, C₁₂-C₁₄ alcohol glycidyl ether, butane glycidyl ether, hexane diglycidyl ether, cyclohexane dimethyl diglycidyl ether or glycidyl ethers based on polyethylene glycols or polypropylene glycols. If necessary the viscosity of the epoxy resins can be reduced further by adding these reactive diluents.

The amines used to prepare the adduct can be used individually or in a mixture.

The compositions of the invention can be used very generally as casting resins and can be employed in the formulation adapted to the particular field of use, for example, as adhesives, as matrix resins, as tooling resins or as coating materials.

The invention further provides the cured products obtainable by curing a curable composition of the invention.

Analytical methods:

Viscosity

Measured with the Haake RV 20 rotational viscometer in accordance with the manufacturer's instructions.

Amine number

Measured in accordance with DIN 16945.

Tecam time

Gelation time as measured with the Tecam gelation timer GT3 from Techne, Cambridge, GB at 23°C and 50% relative humidity; Sample mixture of resin and hardener = 250 g.

Colour number

Measured in accordance with DIN 53995 using the Lovibond colorimeter (Gardner colour number).

Examples:

Isocyanato-containing polyether urethane monoepoxides

Stage 1 : Polyalkylene glycol monoglycidyl ethers

The polyalkylene glycol monoglycidyl ethers are prepared by a conventional process - subjecting epichlorohydrin to addition reaction with the polyalkylene glycol at 30°C - 60°C in the presence of aqueous sodium hydroxide solution and subsequently separating off the aqueous sodium chloride solution.

The properties of the polyalkylene glycol monoglycidyl ethers prepared in this way are depicted in Table 1 :

Table 1:

Key: ' polypropylene glycol; polyethylene glycol

Stage 2

Reaction of the polyalkylene glycol monoglycidyl ethers (PAGMGE) with diisocyanates to give isocyanato-containing polyether urethane monoepoxides:

The diisocyanate is charged to the reaction vessel. The polyalkylene glycol monoglycidyl ether is homogenized with 0.1 % dibutyltin laurate (based on the total amount) and is added dropwise over about 2 hours to the isocyanate, which has been preheated to about 40°C, dropwise addition taking place at a rate such that the temperature does not exceed 60°C.

The properties of the products thus prepared are shown in Table 2: Table 2

Key: ¹⁾ corresponding in each case to 1 epoxide equivalent; ^corresponding in each case to 1 mol of diisocyanate; ³⁾ also corresponds to isocyanate equivalent (theory); ⁴⁾ IPDI = isophorone diisocyanate, TDI = tolylene diisocyanate, TMDI = tetramethylene diisocyanate

Use examples:

Example 9

Preparation of a dispersion (reaction of the isocyanate group of the isocyanato-containing polypropylene monoglycidyl ethers of the invention with the hydroxyl groups of the solid resin).

1 800 g of a solid resin having an epoxide equivalent of 500 and a hydroxyl number of 125

(Araldite 7071 from Vantico GmbH) are homogenized in a reaction vessel with 700 g of anhydrous xylene at 60°C. Over the course of 45 minutes, 100 g of the isocyanate from

Example 8 in solution in xylene are added. After a reaction time of 30 minutes the solvent is removed. This gives a resin having an epoxide equivalent of 498.

250 g of the resin prepared are homogenized with 20 g of isopropanol and 30 g of methoxypropanol at 75°C and over the course of 5 minutes 200 g of fully deionized water at a temperature of 70°C are added. This gives a stable dispersion having a viscosity of 5 5 mPa«s (at 25°C), measured with the Haake rotational viscometer, spindle MVI, reaction rate 128 revolutions per minute. 100 g of the dispersion are mixed with 15 g of a polyamine adduct hardener (Aradur 36 from Vantico GmbH) and 13.5 g of water. The viscosity of the mixture is 1 Pa»s. The mixture is applied as a film using a 40 μm spiral. After 5 minutes the film is dust dry (DIN 53150). The film thickness is 12 μm.

Example 10: Preparation of an adduct with isocyanato-containing polyether urethane monoepoxides and comparative example

80 g of isophorone diamine are charged to the reaction vessel and heated to 60°C. Over the course of 30 minutes, 40 g of the product from Example 5 are added dropwise. The mixture is stirred for 30 minutes thereafter. Subsequently 80 g of benzyl alcohol are added. The adduct formed has a viscosity of 269 mPa«s and a colour number of <1 (Gardner). The amine equivalent is 124 (arithmetical). 67 g of the amine adduct prepared in this way are homogenized with 100 g of a bisphenol A diglycidyl ether having an epoxide equivalent weight of 185 (Araldite GY 250 from Vantico AG) and applied to a glass plate using a 100 μm spiral.

After 24 hours at 20°C a tack-free high-gloss film is formed. The Tecam time is 45 minutes.

The Shore hardness D after 7 days at 23°C is 79.

The binder mixture is additionally applied in accordance with DIN 53283 to a steel panel. The tensile shear strengths are measured after 7 days of curing at room temperature. The tensile shear strength (DIN 53283) is 5 N/mm.

Comparative example

An adduct prepared in comparison thereto from 80 g of isophoronediamine, 40 g of bisphenol A diglycidyl ether (GY 250) in 80 g of benzyl alcohol results in accordance with the same method in a tensile shear strength of only 3.1 N/mm.

Example 11 : Formulation of the isocyanato-containing polyurethane epoxide with epoxy resin and comparative example

80 g of a bisphenol F diglycidyl ether having an epoxide equivalent of 168 (Araldite GY 287 from Vantico) are homogenized with 20 g of the product from Example 6. The viscosity is 9.5 Pa-s/25°C. 100 g of the formulation are homogenized with 52 g of a cycloaliphatic amine adduct (Aradur 46 from Vantico). The mixture is applied to a glass plate by means of a 100 μm spiral. After 24 hours a tack-free high-gloss film is obtained. The Shore hardness D is 68 after 24 hours and 71 after 48 hours (at 23°C). The Tecam time is 30 minutes.

100 g of the above-described formulation of 80 g of a BPF diglycidyl ether and 20 g of the product from Example 6 are mixed with 50 g of an aminoimidazoline from monomeric fatty acid and the mixture is applied in accordance with DIN 53283 to a steel panel. The tensile shear strength after 7 days of curing at RT is 8 N/mm².

Comparative example

In comparison thereto 100 g of an unmodified bisphenol F diglycidyl ether are mixed with 50 g of the above-described aminoimidazoline and the mixture is applied by the same method. The tensile shear strength after 7 days of curing at RT is only 6 N/mm². Example 12

Use of the isocyanato-containing polyether urethane epoxide in polyurethane formulations

60 g of a branched polyether urethane with crosslinkable blocked isocyanate groups

(Desmocap 11 from Bayer AG) are homogenized with 20 g of the product from Example 7 and 20 g of a bisphenol A diglycidyl ether having an epoxide equivalent of 185 (Araldite GY

250 from Vantico). The viscosity of this mixture is 38 Pa«s/25°C. Subsequently 12 g of a cycloaliphatic polyamine (Laromin C 260 from Bayer AG) are added and the mixture is stirred to homogeneity and cast to form mouldings. After 7 days at 23°C and a subsequent 24 hours at 60°C the following values are measured at 23°C: tensile strength (DIN 53455): 5.1 MPa; elongation at break (DIN 53455): 65%;

Shore hardness D (DIN 53505): 32

In comparison hereto, 80 g of Desmocap 11 and 20 g of the abovementioned bisphenol A diglycidyl ether are homogenized. The viscosity of this mixture is approximately

70 Pa»s/25°C. This mixture is likewise stirred to homogeneity with 12 g of Laromin C 252 and cured as described above. The following values are measured: tensile strength: 4.3 MPa; elongation at break: 63%; Shore hardness D: 26.

Claims

1. Curable composition comprising

B) an amine compound,

in which R^ and R₂ independently of one another are a radical -H or -CH₃, n = 0 - 50, and R₃ is an aliphatic, araliphatic, aromatic, cycloaliphatic alkylene radical, and

D) optionally auxiliaries and additives and/or diluents.

2. Curable composition according to Claim 1 , characterized in that component C) is present as a constituent in the epoxy resin A).

3. Curable composition according to one of Claims 1 or 2, characterized in that component C) is present as an amine adduct in the amine compound B).

4. Curable composition according to one of Claims 1 to 3, further comprising

E) an optionally blocked isocyanate, and

F) optionally a hydroxyl compound having on average at least two hydroxyl groups in the molecule.

5. Curable composition according to one of Claims 1 to 4, characterized in that in the formula (I) the repetition factor n = 5 - 35.

6. Curable composition according to one of Claims 1 to 5, characterized in that the polyalkylene glycol used to prepare component C) is a polypropylene glycol.

7. Curable composition according to one of Claims 1 to 6, characterized in that the diisocyanate used to prepare component C) is selected from hexamethylene diisocyanate, tolylene diisocyanate and isophorone diisocyanate.

8. Curable composition according to Claim 7, characterized in that the diisocyanate used to prepare component C) is isophorone diisocyanate.

9. Cured product obtainable by curing a composition according to one of Claims 1 to 8.

10. Use of a curable composition according to one of Claims 1 to 8 as a casting resin, adhesive, matrix resin, tooling resin or as a coating material.

11. Use of an isocyanato-containing polyether urethane monoepoxide of the general formula (I),

in which Ri and R₂ independently of one another are a radical -H or -CH₃, n = 0 - 50, preferably n = 5 - 35, and R₃ is an aliphatic, araliphatic, aromatic, cycloaliphatic alkylene radical, for preparing stable aqueous epoxy resin dispersions.