CURABLE (METH)ACRYLATE COMPOSITIONS

Abstract

A two-part curable (adhesive) composition comprising a Part A and a Part B: Part A comprising: (i) a curable (meth)acrylate component; (ii) a peroxide; and (iii) a phenolic lipid; and Part B comprising: (i) a curable (meth)acrylate component; and (ii) a transition metal component. These compositions are tack free, demonstrate good cure through volume and desirable bond strengths on both active and passive substrates. The two-part curable (adhesive) composition can cure across relatively large bond gaps and are non-volatile.

Claims

1. A two-part curable composition comprising a Part A and a Part B: Part A comprising: (i) a curable (meth)acrylate component; (ii) a peroxide; and (iii) a phenolic lipid; and Part B comprising: (i) a curable (meth)acrylate component; and (ii) a transition metal component.

2. The curable composition according to claim 1 wherein the phenolic lipid comprises a polyol comprising one or more moieties having the following structure: ##STR00027## wherein R is C.sub.10-C.sub.30 aliphatic, optionally substituted with heteroatoms selected from O, N or S, and wherein R may be optionally substituted with at least one of a hydroxyl, a C.sub.1-C.sub.6 alkyl, a C.sub.1-C.sub.6 alkoyl, a C.sub.1-C.sub.6 ether, oxo, epoxy or glycidoxy; R.sup.1 may be hydrogen or hydroxyl; R.sup.2 may be hydrogen, a carboxyl group or an ester.

3. The curable composition according to claim 1 wherein the phenolic lipid comprises one or more moieties having the following structure: ##STR00028## wherein R is a C.sub.10-C.sub.30 aliphatic group, optionally R is a C.sub.12 to C.sub.20 aliphatic group.

4. The curable composition according to claim 1, wherein the phenolic lipid comprises a cashew nutshell liquid based polyol.

5. The curable composition according to claim 4, wherein the cashew nutshell liquid based polyol is selected from the group consisting of a cashew nutshell liquid based polyether polyol, a cashew nutshell liquid based polyester polyol, a cashew nutshell liquid based Mannich polyol, a cashew nutshell liquid based polyester diol and/or combinations of two or more of these.

6. The curable composition according to claim 1, wherein the phenolic lipid comprises a cashew nutshell liquid based polyester diol comprising one or more moieties having the following structure: ##STR00029## wherein R is C.sub.10-C.sub.30 aliphatic, optionally substituted with heteroatoms selected from O, N or S, and wherein R may be optionally substituted with at least one of a hydroxyl, a C.sub.1-C.sub.6 alkyl, a C.sub.1-C.sub.6 alkoyl, a C.sub.1-C.sub.6 ether, oxo, epoxy or glycidoxy; R.sup.1 may be hydrogen or hydroxyl; R.sup.2 may be hydrogen, a carboxyl group or an ester.

7. The curable composition according to claim 6, wherein the polyester diol comprises one or more moieties having the following structure: ##STR00030## wherein R is a C.sub.10-C.sub.30 aliphatic group, optionally R is a C.sub.12 to C.sub.20 aliphatic group.

8. The curable composition according to claim 1 wherein the phenolic lipid comprises a resorcinol lipid.

9. The curable composition according to claim 1 wherein the phenolic lipid comprises an oligomer having up to 10 repeating phenolic lipid units.

10. The curable composition according to claim 1 wherein the phenolic lipid comprises a phenolic lipid dimer.

11. The curable composition according to claim 1 wherein the phenolic lipid comprises a phenolic ring with at least one C.sub.5 to a C.sub.30 side chain attached to the ring.

12. The curable composition according to claim 1 wherein the phenolic lipid component comprises a phenolic ring with at least one C.sub.10 to a C.sub.20 side chain attached to the ring.

13. The curable composition according to claim 1 wherein the phenolic lipid component comprises a phenolic ring with at least one C.sub.15 side chain attached to the ring.

14. The curable composition according to claim 1 wherein the phenolic lipid component is derived from cashew nutshell oil.

15. The curable composition according to claim 11 wherein the side chain terminates in an allyl group.

16. The curable composition according to claim 11 wherein the side chain comprises at least two double bonds.

17. The curable composition according to claim 16 wherein at least two double bonds are conjugated.

18. The curable composition according to claim 1 wherein the phenolic lipid component comprises cardol or an oligomer having up to 10 repeating units of cardol: ##STR00031##

19. The curable composition according to claim 18 wherein the phenolic lipid component comprises a dimer of cardol: ##STR00032##

20. The curable composition according to claim 1 wherein the phenolic lipid component comprises cardanol or an oligomer having up to 10 repeating units of cardanol: ##STR00033##

21. The curable composition according to claim 20 wherein the phenolic lipid component comprises a dimer of cardanol: ##STR00034##

22. The curable composition according to claim 1 wherein the phenolic lipid comprises anarcardic acid or an oligomer having up to 10 repeating units of anarcardic acid: ##STR00035##

23. The curable composition according to claim 22 wherein the phenolic lipid comprises a dimer of anarcardic acid: ##STR00036##

24. The curable composition according to claim 1 wherein phenolic lipid component comprises a phenolic lipid diol.

25. The curable composition according to claim 1 wherein the phenolic lipid component contains a cardanol glycidyl ether.

26. The curable composition according to claim 20, wherein the cardanol glycidyl ether has the following structure: ##STR00037##

27. The curable composition according to claim 1 wherein the phenolic lipid is present in an amount of from about 10 to about 30% by weight based on the total weight of the composition.

28. The curable composition according to claim 1 wherein the phenolic lipid is present in an amount of from about 12 to about 25% by weight based on the total weight of the composition.

29. The curable composition according to claim 1 wherein the phenolic lipid is present in an amount of from about 15 to about 20% by weight based on the total weight of the composition.

30. The curable composition according to claim 1 wherein the transition metal in the transition metal component is cobalt and the transition metal component is a cobalt compound.

31. The curable composition according to claim 1 wherein the transition metal in the transition metal component is cobalt in a cobalt (II) form.

32. The curable composition according to claim 1 wherein the transition metal component includes polymer bound cobalt, cobalt salt, cobalt naphthenate, and any combination thereof.

33. The curable composition according to claim 1 wherein the transition metal component includes cobalt neodecanoate.

34. The curable composition according to claim 1 wherein the transition metal component is present in an amount from about 0.1 to about 5%.

35. The curable composition according to claim 1 wherein the transition metal component is present in an amount from about 0.2 to about 4% by weight based on the total weight of the composition.

36. The curable composition according to claim 1 wherein the transition metal component is present in an amount from about 0.5 to about 2% by weight based on the total weight of the composition.

37. The curable composition according to claim 1 wherein the curable (meth)acrylate component is selected from polyethylene glycol dimethacrylate, hydroxypropyl methacrylate, isopropylidene glycerol methacrylate and combinations thereof.

38. The curable composition according to claim 1 wherein the curable (meth)acrylate component is present in an amount of from about 20% to about 80% by weight, based on the total weight of the composition.

39. The curable composition according to claim 1 wherein the curable (meth)acrylate component is present in an amount of from about 30 to about 60% based on the total weight of the composition

40. The curable composition according to claim 1 wherein the curable (meth)acrylate component is present in an amount of from about 35% to about 50% based on the total weight of the composition.

41. The curable composition according to claim 1 further comprising: a thickener component in an amount from about 20 to about 40% by weight based on the total weight of the composition.

42. The curable composition according to claim 41 wherein the thickener component is present in an amount from about 24 to about 36% by weight based on the total weight of the composition.

43. The curable composition according to claim 41 wherein the thickener component is present in an amount from about 28 to about 32% by weight based on the total weight of the composition.

44. The curable composition according to claim 41 wherein the thickener component is selected from propoxylated bisphenol A fumarate, fumed silica and combinations thereof.

45. The curable composition according to claim 1 further comprising: a chelating agent.

46. The curable composition according to claim 45 wherein the chelating agent is the tetrasodium salt of ethylenediamine tetraacetic acid (“EDTA”).

47. The curable composition according to claim 45 wherein the chelating agent is present in an amount from about 0.001% to about 4% by weight based on the total weight of the composition.

48. The curable composition according to claim 45 wherein the chelating agent is present in an amount from about 0.1% to about 3% by weight based on the total weight of the composition.

49. The curable composition according to claim 45 wherein the chelating agent is present in an amount from about 1% to about 2% by weight based on the total weight of the composition.

50. The curable composition according to claim 1 further comprising: a stabiliser component.

51. The curable composition according to claim 50 wherein the stabiliser component is butylated hydroxy toluene naphthaquinone.

52. The curable composition according to claim 50 wherein the stabiliser component is present in an amount of from about 0.5 to about 5%, by weight based on the total weight of the composition.

53. The curable composition according to claim 50 wherein the stabiliser component is present in an amount of from about 1 to about 4.5% by weight based on the total weight of the composition.

54. The curable composition according to claim 50 wherein the stabiliser component is present in an amount of from about 1 to about 2.5% by weight based on the total weight of the composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings in which:

[0085] FIG. 1 is a tensile strength evaluation of phenolic lipid (GX9203) in a 2-part acrylate formulation on a variety of substrates;

[0086] FIG. 2 is an evaluation of the tensile strength of 2-part acrylate formulations where the phenolic lipid content is varied;

[0087] FIG. 3 is an evaluation of the tensile strength of 2-part acrylate formulations using different monomers;

[0088] FIG. 4 is an evaluation of the tensile strength of 2-part acrylate formulations with varying filler/thickener content; and

[0089] FIG. 5 shows the tensile strength across gap on grit blasted mild steel (GBMS) for varying levels of silica.

DETAILED DESCRIPTION

[0090] The current invention addresses a market need for a curable composition that can provide a tack free surface, cure through volume and strengths on active and passive metals. The invention was demonstrated on mild steel, stainless steel, aluminium, PVC, PMMA and polycarbonate plastics.

Definitions

[0091] Unless otherwise specified the chemical nomenclature used herein has its usual meaning. As the person skilled in the art is well aware, wavy bonds indicate an attachment point, for example, the compound represented by Rz-X-Ry, where X is:

##STR00024##

represents the following compound:

##STR00025##

[0092] The term “glycidoxy” should be understood as a group having the following formula:

##STR00026##

[0093] The term “moiety” should be understood as being a sub-unit or substructure within a molecule.

[0094] The term Mannich polyol should be understood as a polyol comprising β-amino carbonyl functionality.

[0095] The term “liquid” should be understood as meaning a liquid at room temperature.

[0096] In the following examples for convenience the percentage by weight (% wt) is not based on the total weight of the composition but instead is expressed based on the weight of the part of the composition in which the component is present. Where reference is made to the percentage by weight based on the total weight of the composition this is based on the overall weight of the combined parts and taking into account a mixing ratio. So the percentage by weight based on the total weight of the composition represents the percentage by weight of each component relative to the combined overall weight of the mixed parts.

[0097] The formulation is outlined in Tables 1 and 2

TABLE-US-00001 TABLE 1 Material (Part A) % wt Polyethylene glycol Dimethacrylate 39.82 Butylated Hydroxytoluene - Stabiliser 0.1 EDTA Stabiliser 1.5 Phenolic lipid (GX9203) 26.64 Propoxylated Bisphenol A Fumarate 30.44 (Thickener) 1,1,3,3-Tetramethylbutyl Hydroperoxide 1.50

TABLE-US-00002 TABLE 2 Material (Part B) % wt Polyethylene glycol Dimethacrylate 66.43 Butylated Hydroxytoluene 0.0122 Propoxylated Bisphenol A Fumarate 30.64 Cobalt Neodecanoate (10%) 2.92

[0098] The composition is prepared by mixing/dissolving the raw materials in Tables 1 and 2 with moderate heating (45° C.) to form the respective parts of the composition. The Part A and Part B compositions are then mixed in a ratio of two parts of Part A with one part of Part B immediately prior to application.

[0099] The mixed adhesive is applied to one side of an adherend which is are lap shears (e.g. metal or plastic lapshear) and the assembly is clamped to maintain contact between the adherends. The clamped assembly is allowed to cure for a period of 24 hours, and the tensile strength break force is determined on an Instron machine according to ASTM D1002-05.

[0100] The results of testing of the composition of Example 1 with various substrates are set out in FIG. 1. The cure strength results on active and inactive metal surfaces show substrate independence, which is further highlighted by the strength results on plastic substrates (PMMA, PC and PVC).

Example 2

[0101] Variation in content of Cardolite GX9203 phenolic lipid in two-part acrylate formulation:

TABLE-US-00003 Material (Part A) % wt % wt % wt Polyethylene glycol 66.46 56.46 46.46 Dimethacrylate Butylated Hydroxytoluene 0.1 0.1 0.1 EDTA Stabiliser 1.5 1.5 1.5 Phenolic lipid (GX9203) 0 10 20 Propoxylated Bisphenol A 30.44 30.44 30.44 Fumarate 1,1,3,3-Tetramethylbutyl 1.50 1.50 1.50 hydroperoxide

TABLE-US-00004 Material (Part B) % wt Polyethylene glycol 66.43 Dimethacrylate Butylated Hydroxytoluene 0.0122 Propoxylated Bisphenol A 30.64 Fumarate Cobalt Neodecanoate (10%) 2.92

TABLE-US-00005 Tack Free Time Phenolic lipid Content (% wt) Tack Free Time (Hours)  0  24+ 10  24+ 20 <24 

[0102] The mixed adhesive is applied to one side of an adherend (metal or plastic lapshear) and the assembly is clamped to maintain contact between the adherends. The clamped assembly is allowed to cure for a period of 24 hours, and the tensile strength break force is determined on an Instron according to ASTM D1002-05.

[0103] FIG. 2 shows that % wt content of the phenolic lipid (GX-9203) in the 2-part acrylate formulation plays a significant role in the tensile strength on both active and inactive substrates.

Example 3

Variation in Monomer Type

[0104] Variation in monomer type in two part acrylate formulation with Cardolite GX9203 Phenolic lipid

TABLE-US-00006 Material (A Part) % wt % wt Hydroxypropyl Methacrylate (HPMA) 39.82 0 Isopropylidene glycerol methacrylate (IPGMA) 0 39.82 Butylated Hydroxytoluene 0.1 0.1 EDTA Stabiliser 1.5 1.5 Phenolic lipid 26.64 26.64 Propoxylated Bisphenol A Fumarate 30.44 30.44 1,1,3,3-Tetramethylbutyl hydroperoxide 1.5 1.5

TABLE-US-00007 Material (B Part) % wt % wt Hydroxypropyl Methacrylate 66.43 0 Isopropylidene glycerol methacrylate (IPGMA) 0 66.43 Butylated Hydroxytoluene 0.0122 0.0122 Propoxylated Bisphenol A Fumarate 30.64 30.64 Cobalt Neodecanoate (10%) 2.92 2.92

TABLE-US-00008 Tack Free Time Monomer Tack free Time (Hours) Hydroxypropyl Methacrylate (HPMA) <24 Isopropylidene glycerol methacrylate <24 (IPGMA)

[0105] FIG. 3 shows the variation in tensile strength based on monomer source, where the use of dimethacrylate monomer (PEGMA) outperforms mono-methacrylates like HPMA and IPGMA.

Example 4

[0106] Replacement of propoxylated Bisphenol A Fumarate with silica in two part acrylate formulations with Cardolite GX9203 Phenolic lipid

TABLE-US-00009 Material (Part A) % wt % wt % wt Polyethylene glycol Dimethacrylate 68.26 65.26 60.26 Butylated Hydroxytoluene 0.1 0.1 0.1 (PM17) EDTA Stabiliser 1.5 1.5 1.5 Phenolic lipid (GX9203) 26.64 26.64 26.64 Silica (Aerosil 200 - Hydrophilic) 2 5 10 1,1,3,3-Tetramethylbutyl 1.5 1.5 1.5 hydroperoxide

TABLE-US-00010 Material (Part B) % wt % wt % wt Polyethylene glycol Dimethacrylate 95.07 92.07 87.07 Butylated Hydroxytoluene 0.0122 0.0122 0.0122 Cobalt Neodecanoate (10%) 2.92 2.92 2.92 Silica (Aerosil 200 - Hydrophilic) 2 5 10

TABLE-US-00011 Tack Free Time Silica Content (% wt) Tack Free Time (Hours)  2 24-48  5 <24 10 <24

[0107] FIG. 4 shows the relationship between filler/thickener content and tensile strength, where propoxylated Bisphenol A fumarate can be replaced by hydrophobic silica to improve the “consistency” of the adhesive without impacting tensile strength.

[0108] FIG. 5 shows the tensile strength across gap on grit blasted mild steel (GBMS) for varying levels of silica.

[0109] The words “comprises/comprising” and the words “having/including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0110] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.