WO1995018183A1

WO1995018183A1 - Epoxy resins compatible with polyamine curing agents

Info

Publication number: WO1995018183A1
Application number: PCT/US1994/014550
Authority: WO
Inventors: A. Frank Leo
Original assignee: Henkel Corp
Current assignee: Henkel Corp
Priority date: 1993-12-29
Filing date: 1994-12-23
Publication date: 1995-07-06
Anticipated expiration: 1996-06-29

Abstract

The incorporation of polyurethane poly(meth)acrylate(s) into a composition comprising epoxy resin(s), multifunctional (meth)acrylate ester(s) of a polyol which forms an ester with (meth)acrylic acid, and a polyamine curing agent results in cured epoxy resin(s) that are hard and nonbrittle with high impact resistance and finds use as an adhesive or coating.

Description

EPOXY RESINS COMPATIBLE WITH POLYAMINE CURING AGENTS BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to epoxy resins and their uses. More particularly, the invention relates to epoxy resin compositions compatible with polyamine curing agents.

2. Statement of Related Art

U.S. 4,051,195 relates to blends of an epoxide resin and a poiy(meth)acrylate ester, which cure rapidly with aliphatic polyamine curing agents even at low temperatures. Such compositions can be employed as coatings, adhesives, castings, moldings and the like at high solids contents, including 100% solids content (so-called soiventless compositions).

While these compositions comprise an important advance in the art, since the cured compositions can be formulated to range from flexible to very hard, the latter type tend to be brittle and to have low impact resistance, which are serious disadvantages for their use as coatings, moldings, castings, and the like.

U.S.4,547,562 discloses soiventless polymeric compositions suitable for coatings and moldings formed by the addition reaction product of a first component comprising mono, di or poly amines, amine-terminated structures or an adduct of mono, di or polyamines with mono, di or polyfunctional acrylates or epoxides; and the second component comprising mono, di or poly acrylates, mixtures of mono, di or poly acrylates, or a mixture of mono, di or poly acrylates and mono, di or polyfunctional epoxides and/or glycidyl esters of acrylic acid or methacrylic acid.

Such compositions when cured can be used as adhesives, varnishes, lacquers, paints, or sealants. However, here again when used as coatings the coatings tend to be brittle, with low impact resistance.

This patent also contains the teaching that isocyanate and hydroxyl-terminated polyurethanes have high viscosities and "cannot be used as components of a liquid, soiventless system" (column 3, lines 1-8).

DESCRIPTION OF THE INVENTION

Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term "about".

It has now been discovered that the presence of small quantities of polyurethane poly(meth)acrylates in certain two component liquid soiventless epoxy resin systems results in cured epoxy resins that are hard, nonbrittle, and possess high impact resistance. This result is surprising, especially in view of the teachings of U.S.4,547,562 that hydroxyl-terminated polyurethanes cannot be used in such systems.

The two component epoxy resin system of the invention comprises A) a liquid epoxy resin component containing

a) at least one epoxy resin having at least two 1,2-epoxy groups; b) at least one multifunctional (meth)acrylate ester which is a polyol having at least two hydroxyl groups, in the form of an ester with acrylic acid or methacrylic acid; and c) at least one polyurethane poly(meth)acrylate;

and

B) a liquid hardener component containing a polyamine curing agent.

The epoxy resin (component A) a) above) includes those epoxy resins having two or more 1,2-epoxy groups per molecule. The epoxy resins include those set forth in U.S.4,051,195, which patent is expressly incorporated herein by reference. Such epoxy resins are liquid, saturated or unsaturated, aliphatic, cycloaliphatic or heterocyclic and can be either monomeric or polymeric.

Preferred epoxy resins for use herein are the epoxy novolac resins of formula I

where R = H or CH₃ and

n = 0 to 4.

The above epoxy novolac resins of formula I are usually mixtures of ortho, meta and para isomers. Also preferred are epoxy resins of formula II

wherein R= H or CH₃ and

m = 0 to 4.

Even more preferred are epoxy resins of formula II which are the diglycidyl ethers from epichlorohydrin and bisphenol A or bisphenol F, i.e. compounds of Formula II where R is methyl or hydrogen and m = 0.

The multifunctional (meth)acrylate esters (component A)b) above) useful in the practice of the invention include those esters set forth in U.S. 4,051,195, which is expressly incorporated herein by reference. These multifunctional (meth) acrylate esters should have a viscosity not greater than 5000 cps, and preferably not greater than 500 cps. Preferred esters are diols or triols, optionally ethoxylated and/or propoxylated with from 1 to 8 EO and/or PO groups, wherein all hydroxyl groups are in the form of acrylate esters, e.g. trimethaπol triacrylate. Most preferred are esters of the following formulae:

CH₂ = CH - COO(CH₂)_xOOC - CH = CH₂ (III)

wherein x is an integer of from 2-6, and

wherein y is an integer of from 1 -6 and R¹ is H or CH₃.

Examples of compounds within the above formulae include 1,3-propanediol diacrylate, 1,6-hexanediol diacrylate, and tripropyleneglycol diacrylate. Where multifunctional (meth) acrylate esters having a viscosity above 500 cps are present, they are preferably present in relatively small quantities, e.g. from 0.1 to 25%, based on the total weight of (meth)acrylate ester. Such higher viscosity esters are e.g. sugar polyacrylates, and in fact their presence may be useful in increasing the crosslink density of the cured epoxy.

While multifunctional methacrylate esters are within the scope of the invention, these esters are usually somewhat less desirable for use herein than the corresponding multifunctional acrylate esters due to their somewhat slower rates of reaction and more limited miscibility with the epoxy resins.

Where less than all hydroxy groups in the multifunctional (meth)acryiate esters are in the form of esters of (meth)acrylic acid, e.g. in the case of a triol or higher polyol having one or more free hydroxyl groups, the nonesterified hydroxyl groups can be present as such or in the form of C₁-C₃ alkoxy groups, preferably methoxy. It is however usually preferred to esterify all hydroxyl groups with (meth)acrylic acid.

It has also been discovered, and is a feature of this invention, that di(meth)acrylate esters of the formula

wherein R is H or CH₃,

R₁ is H or CH₃, n is an integer of from 0-6,

m is an integer of from 0-6, and

n + m = 1-6, preferably 2-6,

when used as component A)b) above, greatly improves the impact resistance and flexibility of the cured compositions, even without the presence of any polyurethane di(meth)acrylate (component A)c) above).

The polyurethane poly(meth) acrylates (component A)c) above) contain from 2 to 6 (meth) acrylate groups, are aliphatic or aromatic polyurethane derivatives, are highly viscous or solid, having a weight average molecular weight in the range of from 1200 to 5000, preferably 1200 to 1800. They are employed in amounts ranging from 0.1 to 25%, preferably 1 to 15%,and more preferably 1 to 10% by weight, based on the combined weight of components A)a) and A)b). Preferred are polyurethane di-acrylates having a weight average molecular weight in the range of from 1200 to 1800. These polyurethane diacrylates are usually prepared by reacting a diisocyanate with hydroxyethyl acrylate in a 1 :1 molar ratio, so that the resulting adduct contains a free isocyanate group, and then reacting two moles of this adduct with one mole of a dihydroxy polyether or polyester.

The hardener component (component B)) of the present two component epoxy resin systems are aliphatic polyamines such as polyalkyiene polyamines, e.g. ethylenediamine (H₂NCH₂CH₂NH₂) dimethylethylene diamine (CH₃NHCH₂CH₂NHCH₃), diethylenetriamine (H₂NCH₂CH₂NHCH₂CH₂NH₂), tetramethylene diamine (H₂NCH₂CH₂CH₂CH₂NH₂), triethylenetetramine (H₂NCH₂CH₂NHCH₂CH₂NHCH₂CH₂NH₂), hexamethylene diamine (H₂N(CH₂)₆NH₂), etc. Preferred for use herein are polyamide curing agents, i.e. amidoamines obtained by reacting a polyamine such as the above with straight or branched chain saturated aliphatic polycarboxylic acids, e.g. having from 2-50 carbon atoms in the alkylene groups, in which each carboxylic acid group has been reacted with a molecule of a polyamine. The resulting polyamides must contain at least two amine groups that are primary and/or secondary in nature. Preferred polyamide curing agents are the reaction products of one mol of a C₃₆ fatty diacid from the dimerization of a C₁₈ unsaturated fatty acid with two mols of diethylenetriamine or triethylenetetramine. Also, polyamines containing epoxy groups can be employed herein.

In addition to the polyamine curing agent, the hardener component can optionally contain quantities of other ingredients, e.g. from 0.001 to 65% by weight, based on the weight of polyamine curing agent, of ingredients such as accelerators, fillers, reinforcing agents, dyes, pigments and other additives.

In the compositions of the invention, the percentage ratio by weight of component A)a) to component A)b) is from 85:15 to 20:80. The particular ratio selected within the above range is not critical and will depend on the particular components chosen and the properties desired for the cured epoxy product.

Components A and B are used in an equivalent ratio of epoxy groups plus acrylate groups in the epoxy resin component to amine hydrogen atoms in the hardener component of from 0.85:1 to 1:1.15, preferably from 0.95:1 to 1:1.05, and more preferably 1:1.

The two component epoxy resin systems of the invention are applied by mixing together the epoxy resin component and the hardener component in the absence of solvents and applying the mixture at a temperature of from 0° to 150°F, preferably from 40° to 110ºF, and more preferably from 40° to 95ºF.

It is of course also possible to add solvents thereto, such as hydrocarbons, ethers, alcohols, esters, ketones, etc., but due to the liquid nature of the present compositions, such solvents are unnecessary. Moreover, for many applications solvents are highly undesirable, acting to reduce the solids contents, presenting environmental and safety problems, and causing a reduction in physical properties, e.g. in thick coatings of 20-1000 mils, solvents will be trapped in the coatings, resulting in cheesey films.

The two component epoxy resin system can be used as an adhesive system to bond two like or different substrates together as with other epoxy adhesives; as tough resilient nonbrittle coatings having high impact resistance for hard surfaces, including coatings for floors; as casting, molding and potting compositions; and as encapsulating compositions.

The epoxy system can be used immediately after mixing due to its low viscosity, even at a relatively high solids content, and its increased reactivity even at relatively low cure temperatures. Short cure times are also achieved. The cured mixtures exhibit excellent flexibility, impact resistance, and good chemical resistance.

Since the present epoxy system does not require any organic solvent, thick coatings containing 100% solids content, e.g. from 0.5 to 1 inch thick, can be readily applied to a substrate.

The epoxy systems of the invention can also be used as paint compositions, when mixed with paint pigments. The paint coatings resulting from their use are unusually tough, adhesive and chemically resistant.

The invention will be illustrated but not limited by the following examples.

EXAMPLES

Example 1

A two component epoxy resin system is prepared from the following ingredients:

COMPONENT A:

acrylate

parts per equiv. wt. epoxy

Ingredient hundred equivalents

DER 331⁽¹⁾ 60 190 0.316

PHOTOMER^® 6022^rø 20 130 0.154

PHOTOMER^® 4127⁽³⁾ 20 180 0.111

100 0.581

COMPONENT B:

parts per

hundred parts amine amine of Component equiv. wt. hydrogen

Ingredient A equivalents

DETA⁽⁴⁾ 12 20.6 0.581

⁽¹⁾DER 331 is the diglycidyl ether of bisphenol A.

⁽²⁾PHOTOMER® 6022 is an aromatic polyurethane containing six acrylate groups, a viscosity of from 500-800 poises, and a weight average molecular weight of 800.

(³⁾PHOTOMER® 4127 is a neopentylglycol- 2PO- diacrylate.

⁽⁴⁾DETA is diethylenetriamine.

Example 2

A two component epoxy resin system is prepared from the following ingredients:

COMPONENT A:

acrylate

parts per equiv. wt. epoxy ingredient hundred equivalents

DER 331 60 190 0.316

PHOTOMER® 6022 20 130 0.154

PHOTOMER® 4127 20 180 0.111

100 0.581

COMPONENT B:

parts per

hundred parts amine amine of Component equiv. wt hydrogen

Ingredient A equivalents

VERSAMINE® A-50⁽⁵⁾ 25 43 0.581

⁽⁵⁾VERSAMINE ® A-50 is an epoxy derivative of diethylenetriamine.

Example 3

A two component epoxy resin system is prepared from the following ingredients:

COMPONENT A:

acrylate

parts per equiv. wt epoxy

Ingredient hundred equivalents

DER 331 75 190 0.395

PHOTOMER® 4025⁽⁶⁾ 25 270 0.093

100 0.488

COMPONENT B:

parts per

hundred parts amine amine of Component equiv. wt hydrogen

Ingredient A equivalents

DETA 10 20.6 0.488 ⁽⁶⁾PHOTOMER® 4025 is bisphenol A-8EO- diacrylate.

Example 4

A two component epoxy resin system is prepared from the following ingredients:

COMPONENT A:

acrylate

parts per equiv. wt epoxy ingredient hundred equivalents

DER 331 75 190 0.395

PHOTOMER® 4025⁽⁶⁾ 25 270 0.093

100 0.488

COMPONENT B:

parts per

hundred parts amine amine of Component equiv. wt hydrogen

Ingredient A equivalents

VERSAMINE ® A-50 21 43 0.488

Claims

1. A two component epoxy resin system comprising

A) a liquid epoxy resin component containing

a) at least one epoxy resin having at least 21,2-epoxy groups; b) at least one multifunctional (meth)acrylate ester which is a polyol having at least two hydroxyl groups in the form of an ester with acrylic acid or methacrylic acid; and

c) from about 0.1 to about 25% parts by weight, based on the weight of a) plus b), of at least one polyurethane poly(meth)- acrylate; and

B) a liquid hardener component containing a polyamine curing agent.

2. The epoxy resin system of claim 1 wherein from about 1 to about 15% by weight of component A)c) is present in the epoxy resin component.

3. The epoxy resin system of claim 1 wherein component A)c) has a weight average molecular weight in the range of from about 1200 to about 5000.

4. The epoxy resin system of claim 3 wherein the molecular weight of component A)c) is in the range of from about 1200 to about 1800.

5. The epoxy resin system of claim 1 wherein the percentage ratio by weight of component A)a) to component A)b) is from about 85: 15 to about 20:80.

6. The epoxy resin system of claim 1 wherein component A)a) is an epoxy novolac resin of formula II

wherein R = H or CH₃, and n = 0 to 4.

7. The epoxy resin system of claim 6 wherein n in formula I is from 0-2.

8. The epoxy resin system of claim 6 wherein n in formula I is equal to zero or 1

9. The epoxy system of claim 1 wherein component A)b) has a viscosity not greater than about 5000 cps.

10. The epoxy system of claim 9 wherein said viscosity is not greater than about 500 cps.

11. The epoxy system of claim 1 wherein component A)b) is at least one of the following:

(i) a diol or triol having all hydroxy groups in the form of an acrylate ester and wherein the diol or triol is optionally ethoxylated and/or propoxylated with from 1 to 8 EO and/or PO groups; (ii) an acrylate ester of the formula CH₂ = CH - COO(CH₂)_xOOC - CH =CH₂ (III)

wherein x is an integer of from 2-6; and

(iii) an acrylate ester of the formula

R¹

I CH₂ = CH-COO(CH₂CHO)_γOC-CH = CH₂ (IV)

wherein y is an integer of from 1-6 and R is H or CH₃.

12. The epoxy resin system of claim 1 wherein the polyamine curing agent of component B) is a straight or branched chain saturated aliphatic polycarboxylic acid in which each carboxylic acid group is in the form of an amide with a polyamine, wherein the amide contains at least two primary and/or secondary amine groups.

13. The epoxy system of claim 1 wherein component A)b) is at least one di(meth)acryiate ester of the formula

this is revised

v

wherein R is H or CH₃,

R₁ is H or CH₃, n is an integer of from 0-6,

m is an integer of from 0-6,

and n + m = 1-6.

14. The epoxy system of claim 13 wherein in formula IV n + m = 2-6.

15. A curable liquid epoxy resin component comprising

a) at least one epoxy resin containing at least two 1 ,2-epoxy groups; b) at least one multifunctional (meth)acrylate ester which is a polyol having at least two hydroxyl groups in the form of an ester with acrylic acid or methacrylic acid; and

c) from about 0.1 to about 25% parts by weight, based on the weight of a) plus b), of at least one polyurethane poly(meth)acrylate.

16. The epoxy resin component of claim 15 wherein the percentage ratio by weight of component A)a) to component A)b) is from about 85:15 to about 20:80, and from about 1 to about 15% by weight of component A)c) is present therein.

17. A two component epoxy resin system comprising

A) a liquid epoxy resin component containing

a) at least one epoxy resin having at least two 1,2-epoxy groups, and

b) at least one di(meth)acrylate ester of the formula

wherein R is H or CH₃,

R₁ is H or CH₃,

n is an integer of from 0-6,

m is an integer of from 0-6,

and n + m = 1-6;

and

B) a liquid hardener component containing a polyamine curing agent.

18. The epoxy resin system of claim 17 wherein in component A)b) n + m = 2-6.