STRUCTURAL ADHESIVES

Abstract

An adhesive formulation having an adduct of an epoxy resin and an elastomer, a phenoxy epoxy hybrid resin supplied as a solution formed by dissolving a phenoxy resin in a liquid epoxy resin to form a pre-formed dissolution product, a core/shell polymer, and one or more additional epoxy resins. The adhesive formulation may include a curing agent, blowing agent, filler, accelerator, or a combination.

Claims

1. An adhesive formulation comprising: i) an adduct of an epoxy resin and an elastomer; ii) a phenoxy epoxy hybrid resin supplied as a solution formed by dissolving a phenoxy resin in a liquid epoxy resin to form a pre-formed dissolution product, wherein the adhesive formulation contains no more than 10% by weight of phenoxy resin; iii) a core/shell polymer; and iv) one or more additional epoxy resins.

2. The adhesive formulation according to claim 1, wherein the adhesive formulation contains from about 5% to about 20% by weight of the adduct based on the adhesive formulation.

3. The adhesive formulation according to claim 1, wherein the adduct includes about 1:5 to about 5:1 parts of epoxy to elastomer.

4. The adhesive formulation according to claim 1, wherein the elastomer in the adduct is selected from natural rubber, styrene-butadiene rubber, polyisoprene, polyisobutylene, polybutadiene, isoprene-butadiene copolymer, neoprene, nitrile rubber, butyl rubber, polysulfide elastomer, acrylic elastomer, acrylonitrile elastomers, silicone rubber, polysiloxanes, polyester rubber, diisocyanate-linked condensation elastomer, EPDM (ethylene-propylene diene rubbers), chlorosulphonated polyethylene, fluorinated hydrocarbons, and any combination thereof.

5. The adhesive formulation according to claim 4, wherein the adduct of the epoxy resin and the elastomer is derived from a butadiene acrylonitrile rubber.

6. The adhesive formulation according to claim 1, wherein the phenoxy resin is of the formula ##STR00002## where n is from 30 to 100.

7. (canceled)

8. (canceled)

9. (canceled)

10. (canceled)

11. The adhesive formulation according to claim 1, wherein the core/shell polymer include elastomers, polymers, thermoplastics, copolymers, other components, and combinations thereof.

12. (canceled)

13. The adhesive formulation according to claim 11, wherein the core/shell polymer includes a first polymeric material and a second polymeric material, wherein the first polymeric materials and second polymeric material are selected from styrenics, acrylonitriles, acrylates, acetates, polyamides, polyethylenes, and combinations thereof.

14. The adhesive formulation according to claim 1, wherein the core/shell polymer is a graft copolymer in which styrene, acrylonitrile, or methyl methacrylate, are grafted onto a core made from polymers of soft or elastomeric compounds.

15. The adhesive formulation according to claim 14, wherein the core includes other copolymerizable containing compounds, selected from styrene, vinyl acetate, methyl methacrylate, butadiene, and isoprene.

16. (canceled)

17. (canceled)

18. The adhesive formulation according to claim 1, wherein the adhesive formulation contains from 5% to 30% by weight of the core/shell polymer.

19. The adhesive formulation according to claim 1, comprising from 0.001% to 10% by weight of a curing agent.

20. The adhesive formulation according to claim 19, wherein the curing agent is selected from aliphatic or aromatic amines or their respective adducts, amidoamines, polyamides, cycloaliphatic amines, anhydrides, polycarboxylic polyesters, isocyanates, phenol-based resins, and mixtures thereof.

21. (canceled)

22. (canceled)

23. (canceled)

24. The adhesive formulation according to claim 1, wherein the adhesive formulation contains between containing between 2% and 15% by weight of the liquid epoxy resin of the phenoxy epoxy hybrid resin.

25. (canceled)

26. The adhesive formulation according to claim 1, wherein the adhesive formulation comprises a blowing agent, a filler, a curing agent accelerator, or a combination thereof.

27. (canceled)

28. The adhesive formulation according to claim 26, wherein the adhesive formulation comprises the filler, and wherein the filler is selected from particulate materials, beads, microspheres, silica, diatomaceous earth glass, clay, talc, pigments, colorants, glass beads or bubbles, glass, carbon or ceramic fibers, nylon or para-aramid fibers, or a combination thereof.

29. (canceled)

30. (canceled)

31. The adhesive formulation according to claim 1, wherein the adhesive formulation comprises one or more liquid polysulfides.

32. The adhesive formulation according to claim 1, wherein the adhesive formulation comprises the adduct of the epoxy resin and the elastomer in an amount of from 3% to 25% by weight of the adduct based on the adhesive formulation; from 5% to 30% of the core/shell polymer; and from 40 percent by weight to about 75% by weight total epoxy resin, wherein the total epoxy resin is the liquid epoxy resin of the phenoxy epoxy hybrid resin and the one or more additional epoxy resins.

33. The adhesive formulation according to claim 32, wherein the adhesive formulation includes between about 50% by weight and about 75% by weight total epoxy resins.

34. (canceled)

35. (canceled)

36. (canceled)

37. The adhesive formulation according to claim 1, wherein the adhesive formulation has a strength when cured in a wedge impact test at 40 C. of greater than 20 N/mm.

38.-45. (canceled)

Description

EXAMPLE 1

[0076] The following formulation was prepared.

TABLE-US-00001 Ingredient Grams Masterbatch 105 Epoxy elastomer adduct 30 Epalloy 8220 140 Kaneka MX 136 (25% core/shell 12 polymer dissolved in 75% Bisphenol F epoxy resin) Dicydianamide (Amicure CG 1200) 20 Omicure 52 2 Calcibrite OG calcium carbonate 75 Nanopox 510 (40% nano particle 20 size silica in 60% Bisphenol F epoxy resin)

[0077] Masterbatch and the adduct are placed into a sigma blade mixer/extruder, the Nanopox and the Kaneka are then added followed by the calcium carbonate and the epoxy resin. Finally the dicydianamide and the omicure are added and the materials mixed for about 15 minutes and a vacuum is applied to remove any entrapped air.

[0078] The adhesive properties of the formulation were tested by measuring the average T-peel strength at room temperature, the lap shear at room temperature and the wedge impact strength over the temperature range 40 C. to 90 C. The lap shear was measured employing 1.8 mm thick galvanised steel coupons as the substrate. The glass transition temperature of the cured adhesive was 131.4 C.

[0079] The results of the tests were as follows.

TABLE-US-00002 T-peel 9.35 N/mm Lap shear 35.4 MPa Wedge impact 90 C. 36.9 N/mm 23 C. 33.0 N/mm 30 C. 22.3 N/mm 40 C. 21.6 N/mm

[0080] The results show a relatively low drop in wedge impact from 90 C. to 40 C.; considerably less than current automotive crash durable adhesives where the high temperature value can be at least three times the low temperature value. Typical-40 C. values are below 20 N/mm. This low temperature performance coupled with the high Tg has significant benefits.

EXAMPLE 2

[0081] A similar formulation to that of Example 1 was prepared except that an additional 5 grams of the Kaneka MX 136 solution replaced 5 grams of the masterbatch.

[0082] In order to measure the extent of the high temperature degradation of the adhesive properties the lap shear strength (in MPa) was measured over the temperature range of 30 C. to 90 C. using 45 mm wide, 0.8 mm thickness with a 10 mm overlap. The results were as follows.

TABLE-US-00003 Lap Shear Temperature C. Strength 30 25.8 0 23.6 30 21.9 60 21.5 90 20.2

[0083] The results show that the shear strength is largely retained a high temperature showing unusually consistent performance over a broad temperature range.

[0084] The difference in values between Example 1 and 2 may be attributed to the difference in the thickness of the test substrate.

EXAMPLE 3

[0085] The following formulation was prepared in a manner similar to Example 1. [0086] Omicure 525 grams [0087] Dicydianamide (Amicure CG 1200)20 grams [0088] 40% phenoxy/60% Bisphenol Epoxy resin dissolution80 grams [0089] Araldite GY 28290 grams [0090] Paraloid EXL 265050 grams [0091] Epoxy resin elastomer adduct (70%), Hycar 130031 (30%)80 grams

[0092] The adhesive had the following properties [0093] Lap shear: 36.8 MPa [0094] T-peel: 11.33 N/mm [0095] Wedge Impact 30 C: 27.24 N/mm [0096] Wedge Impact 40 C: 25.5 N/mm

EXAMPLE 4

[0097] The following formulation was prepared in a manner similar to Example 1. [0098] Omicure 525 grams [0099] Dicydianamide (Amicure CG 1200)20 grams [0100] 40% phenoxy/60% Bisphenol Epoxy resin dissolution75 grams [0101] Epalloy 8220110 grams [0102] Paraloid EXL 265075 grams [0103] Epoxy elastomer adduct (2-types of solid epoxy, 4-type solid epoxy equal mix) 70%, Hycar 130031 (30%) [0104] Zeospeheres 1200:30 grams

[0105] The adhesive had the following properties [0106] Lap shear: 34.06 MPa [0107] T-peel: 8.75 N/mm [0108] Wedge Impact 30 C: 44.93 N/mm [0109] Wedge Impact 40 C: 38.36 N/mm

EXAMPLE 5

[0110] The following formulation was prepared in a manner similar to Example 1. [0111] Omicure 525 grams [0112] Dicydianamide (Amicure CG 1200)20 grams [0113] 40% phenoxy/60% Bisphenol Epoxy resin dissolution52.5 grams [0114] Epalloy 8220120 grams [0115] Paraloid EXL 265052.5 grams [0116] Epoxy elastomer adduct (60%), Hycar 130013 (20%), Hycar 13008 (20%)30 grams [0117] Calibrite OG75 grams [0118] Thioplast EPS15 (polysulfide)20 grams [0119] Kaneka 13510 grams [0120] Nanopox 51020 grams

[0121] The adhesive had the following properties [0122] Lap shear: 34.84 MPa [0123] T-peel: 10.42 N/mm [0124] Wedge Impact 30 C: 22.9 N/mm [0125] Wedge Impact 40 C: 21.28 N/mm

[0126] The Lap shear test in examples 3 to 5 employed: [0127] MetalGalvanized Steel [0128] Coupon size: 25 mm100 mm1.8 mm [0129] Overlap: 12.5 mm [0130] Bondline thickness: 0.3 mm [0131] Oil: Quaker N6130

[0132] T-Peel test in examples 3 to 5 employed: [0133] MetalGalvanized Steel [0134] Coupon size100 mm25 mm0.7 mm [0135] Bondline thickness0.3 mm [0136] Oil: None.

[0137] The Wedge Impact test employed: [0138] MetalElectrogalvanised Steel [0139] Thickness0.2 mm