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EP-4741438-A1 - OXATHIOLANONE-GROUP CONTAINING ADDITIVE IN A CURABLE EPOXY RESIN COMPOSITION

EP4741438A1EP 4741438 A1EP4741438 A1EP 4741438A1EP-4741438-A1

Abstract

A compound (A) of formula wherein X is a n-valent organic group or H, and n is an integer of 1, 2, 3 or 4, is provided for use as an additive in an amine curable epoxy resin composition, especially for preparing coatings, adhesives, sealants and composite materials.

Inventors

  • PAWAR, MADHURA SHREEKAR
  • RUDOLF, PETER
  • FUKUZUMI, TAKEO
  • KOENIG, Sandra Gloria

Assignees

  • BASF SE

Dates

Publication Date
20260513
Application Date
20241106

Claims (15)

  1. The use of a compound (A) of formula wherein X is a n-valent organic group or H, and n is an integer of 1, 2, 3 or 4, as an additive in an amine curable epoxy resin composition.
  2. The use according to claim 1, wherein compound (A) has a molecular weight of at most 500 g/mol.
  3. The use according to claim 1 or 2, wherein X is a monovalent organic group X 1 or H, said monovalent organic group X 1 is selected from C 1 -C 18 -alkyl; C 1 -C 18 -alkyl substituted with OH, halogen, NR 1 R 2 , C 5 -C 10 -cycloalkyl, C 6 -C 12 -aryl, C 6 -C 12 -aryloxy, C 6 -C 12 -arylthio or C 2 -C 10 -heteroaryl, and / or interrupted with O, S, -COO-, -OCOO-, -CO-, C 5 -C 8 -cycloalkylene, C 6 -C 12 -arylene or C 2 -C 10 -heteroarylene; R 1 and R 2 are independently of one another and at each occurrence C 1 -C 4 -alkyl or phenyl; or R 1 and R 2 together are C 4 -C 6 -alkylene or C 4 -C 6 -alkylene interrupted by O, S and/or NR 3 ; and R 3 is C 1 -C 4 -alkyl; or X is a divalent organic group X 2 , said divalent organic group X 2 is selected from C 1 -C 18 -alkylene and C 1 -C 18 -alkylene substituted with halogen, NR 4 R 5 , C 5 -C 10 -cycloalkyl, C 6 -C 12 -aryl, or C 2 -C 10 -heteroaryl, and/or interrupted with O, S, -COO-, -OCOO-, -CO-, C 5 -C 8 -cycloalkylene, C 6 -C 12 -arylene, C 6 -C 12 -aryleneoxy, C 6 -C 12 -arylenethio, or C 2 -C 10 -heteroarylene; R 4 and R 5 are independently of one another and at each occurrence C 1 -C 4 -alkyl or phenyl; or X is a trivalent organic group X 3 , said trivalent group X 3 is composed of either benzenetriyl, triazine-2,4,6-triyl, 2,4,6-trioxo-1,3,5-triazine-triyl, methylidyne or nitrogen and a divalent organic group X 2a , or X is a tetravalent organic group X 4 , said tetravalent group X 4 is composed of either a group derived from methane or benzene and a divalent organic group X 2a , wherein X 2a is selected from C 1 -C 18 -alkylene; C 1 -C 12 -alkyleneoxy; C 6 -C 12 -arylene; C 6 -C 12 -aryleneoxy; and C 1 -C 18 -alkylene interrupted with O, S, -COO-, C 5 -C 8 -cycloalkylene, C 6 -C 12 -arylene, C 6 -C 12 -aryleneoxy, C 6 -C 12 -arylenethio, or C 2 -C 5 -heteroarylene.
  4. The use according to claim 1, 2 or 3, wherein n is an integer of 1, 2 or 3, preferably 1 or 2.
  5. The use according to any one of the preceding claims, wherein X is a monovalent organic group X 1 or H, said monovalent organic group X 1 is C 1 -C 12 -alkyl; C 1 -C 12 -alkyl substituted with halogen, cyclohexyl, phenyl, phenoxy, phenylthiol and / or interrupted with O, S, -COO-; cyclohexylene or phenylene; or X is a divalent organic group X 2 , said divalent organic group X 2 is selected from C 1 -C 18 -alkylene and C 1 -C 18 -alkylene interrupted with O, S, -COO-, cyclohexylene, phenylene, phenyleneoxy, phenylenethio or X is a trivalent organic group X 3 , said trivalent organic group X 3 is group composed of either benzenetriyl, triazine-2,4,6-triyl, 2,4,6-trioxo-1,3,5-triazine-triyl, methylidyne or nitrogen and a divalent organic group X 2a , wherein X 2a is selected from C 1 -C 12 -alkylene; phenylene, C 1 -C 12 -alkyleneoxy; and C 1 -C 6 -alkylene interrupted with O, S, -COO-, cyclohexylene, phenylene and phenyleneoxy.
  6. The use according to any one of the preceding claims, wherein the compound of formula (I) is a compound of formula wherein Y is a direct bond, O or COO, and p is an integer of 1 to 9, and q is an integer of 0 to 9; or a compound of formula wherein X 2 is C 1 -C 18 -alkylene; C 1 -C 18 -alkylene interrupted with O, S, COO, C 5 -C 8 -cycloalkylene, phenylene, phenyleneoxy, phenylenethio, and / or or a mixture thereof.
  7. The use according to any one of the preceding claims, wherein the compound of formula (I) is a compound of formula (Ib), wherein the divalent group X 2 is selected from wherein r is 2, 3 or 4; wherein s is about 1 to 10, preferably s is about 1 to 5; wherein W is CH 2 , C(CH 3 ) 2 , CH(CH 3 ), C(CH 3 )(C 2 H 5 ) or SO 2 .
  8. The use according to any one of the preceding claims, wherein the amine curable epoxy resin composition comprises an epoxy resin component (i) and a hardener component (ii).
  9. The use according to any one of the preceding claims, wherein the additive is used as a viscosity stabilizer of the epoxy resin component (i) comprising an epoxy resin (B) and a filler.
  10. A curable epoxy resin composition comprising a) a compound (A) of formula (I), as defined in any of claims 1 to 7; b) an epoxy resin (B); and c) a curing agent (C) comprising at least two amino groups, selected from a primary amino group, a secondary amino group and any combination thereof; wherein the equivalent ratio of groups of formula of compound (A) to epoxy groups of epoxy resin (B) is 0.45 : 1 to 0.05 : 1.
  11. The curable composition according to claim 10, wherein the equivalent ratio of groups of formula (II) of compound (A) to epoxy groups of epoxy resin (B) is 0.4 : 1 to 0.1 : 1.
  12. The curable composition according to claim 10 or 11, wherein the epoxy resin (B) comprises at least one polyglycidyl ether of an aromatic, an aliphatic or a cycloaliphatic polyol, preferably at least one polyglycidyl ether of an aromatic polyol.
  13. The curable composition according to claim 10, 11 or 12, wherein the curable epoxy resin composition is a two-pack formulation comprising (i) an epoxy resin component containing a) the compound (A), b) the epoxy resin (B), and d) optionally a filler, and (ii) a hardener component containing c) the curing agent (C).
  14. The curable composition according to any one of the claims 10 to 13, wherein the curable epoxy resin composition or the epoxy resin component is essentially free of a conventional reactive diluent selected from a glycidyl ether of an aliphatic polyol having 2 to 8 carbon atoms, a glycidyl ether of an unsaturated polyol having 2 to 8 carbon atoms, a glycidyl ether of a cycloaliphatic polyol having 3 to 8 carbon atoms, and a glycidyl ether of an aromatic polyol having 6 to 8 carbon atoms.
  15. The use of a curable epoxy resin composition, as defined in any of claims 10 to 14, for preparing an adhesive, a sealant, a coating or a composite material.

Description

The present invention relates to the use of an oxathiolanone group-containing compound as an additive in an amine curable epoxy resin composition, to an amine curable epoxy resin composition comprising said additive and to the use thereof for preparing an adhesive, a sealant, a coating or a composite material. Background of the invention Epoxy resins are one of the most important classes of thermosetting polymers used in industry. Epoxy resins are usually defined as oligomeric compounds having on average more than one epoxy group per molecule which are converted into thermosetting polymers by reaction of suitable hardeners or by polymerization of the epoxy groups. Due to their various properties like corrosion and humidity resistance, chemical resistance, for example, a high resistance towards organic solvents or alkalis, mechanical strength and electrical insulation as well as due to relative low costs, cured epoxy resins are used in a versatile field of applications such as paints, composites, coatings, adhesives, automotives and the aerospace industry. They may serve as a matrix for fiber composites and are often a major constituent in electrical laminates, structural adhesives, casting resins, and powder coatings. Reaction with hardeners / curing agents converts the epoxy resin into three-dimensionally cross-linked thermoset materials. Because of usual high cross-linking density, many of the systems suffers from some undesired mechanical properties, like brittleness. The epoxy resins typically have a high viscosity, which makes the application more difficult. Moreover, the high viscosity of the resins frequently limits the use of fillers, which is usually desirable for the purpose of modifying mechanical properties of the cured resin composition. In many cases, the use of fillers allows a reduction of costs of finally produced products, like coatings. Further, the curing reaction by adding polyamines as a curing agent to the epoxy resins often show volume shrinkage. The volume shrinkage during the curing reaction causes voids and micro-cracks in the cured material, and thus results in lowering the mechanical strength of the material, for example, contact failure between the adhesive and the substrate or corrosion of the substrate. Therefore, it is common to add diluents to the curing reaction of the epoxy resin and polyamines, like solvents or especially reactive diluents. Reactive diluents are substances of low molecular weight which have functional groups capable of reacting with epoxy groups of the epoxy resin with the amino groups of the hardener. The reactive diluents that are suitable for epoxy resins are typically monofunctional or polyfunctional oxiranes. Known reactive diluents improve the viscosity properties of the epoxy resin composition. However, in many cases they are detrimental to the hardness of the cured product or result in other poorer stability properties. In the prior art, various reactive diluents based on S-containing cyclic carbonates are described. US 3,554,967 discloses the addition of ethylene trithiocarbonate to an amine curable epoxy resin to obtain significantly shorter gel points, compared to a resin without ethylene trithiocarbonate. WO 2006/005386 A1 discloses an amine curing epoxy formulation comprising further a cyclic dithiocarbonate compound containing a -S-CS-O- group and a carboxylic acid like benzoic acid. The addition of the carboxylic acid is described to obtain less shrinkage. EP 2468791 A1 discloses the use of a cyclic dithiocarbonate compound derived from Bisphenol A in an amine curable epoxy resin formulation including a further epoxy-based reactive diluent. The obtained coatings are described to show improved early water resistance. However, the use of a cyclic dithiocarbonate compound as a reactive diluent shows still some disadvantages in view of some properties, like brittleness or handling or stability. The use of a cyclic thiocarbonate compound as a monomer in stoichiometric amounts with polyamines and polyepoxy compounds as a cross-linking agent to yield cured polyurethanes is known from WO 2020/007634 A1 and WO 2019/034470 A1. There is still a need for amine curable epoxy compositions having improved properties, like better processing, brittleness or stability for various applications, especially to find a balance between processing properties like sufficiently long pot-life time and mechanical properties, while the glass transition temperature should not be significantly reduced. Therefore, it is an object of the present invention to provide an additive to be used in amine curable epoxy composition having improved properties, especially compared to known reactive diluents based on cyclic dithiocarbonate compounds. In particular, the pot lifetime of the epoxy composition should be improved, without significantly reducing mechanical properties or other stability properties of the resulting cured products. Further, it is an object of the present inven