Anaerobically curable compositions

Abstract

The present invention relates to anaerobically curable (meth)acrylate compositions, and stabilizers for same.

Claims

1. An anaerobically curable composition comprising: (a) a (meth)acrylate component; (b) a cure inducing component; and (c) at least one stabilizer comprising: at least one C.sub.6-C.sub.50 aliphatic chain, derived from a fatty acid, said stabilizer further comprising at least 2 nitrogen atoms and at least 4 carboxy groups.

2. An anaerobically curable composition according to claim 1, wherein the at least one C.sub.6-C.sub.50 aliphatic chain is a C.sub.7-C.sub.20 alkyl chain.

3. An anaerobically curable composition according to claim 1, wherein the at least one C.sub.6-C.sub.50 aliphatic chain is a C.sub.7-C.sub.12 alkyl chain.

4. An anaerobically curable composition according to claim 1, wherein the at least one C.sub.6-C.sub.50 aliphatic chain is selected from the group of: a C.sub.8 alkyl chain, a C.sub.10 alkyl chain, a C.sub.12 alkyl chain, a C.sub.14 alkyl chain, a C.sub.16 alkyl chain, a C.sub.18 alkyl chain, a C.sub.20 alkyl chain or a C.sub.22 alkyl chain.

5. An anaerobically curable composition according to claim 1, wherein the at least one C.sub.6-C.sub.50 aliphatic chain is derived from a vegetable oil or an animal fat.

6. An anaerobically curable composition according to claim 1, wherein the stabilizer has only 2 nitrogen atoms.

7. An anaerobically curable composition according to claim 1, wherein the stabilizer has 3 or more nitrogen atoms.

8. An anaerobically curable composition according to claim 1, wherein at least one nitrogen atom is covalently bonded to an aliphatic chain derived from a fatty acid.

9. An anaerobically curable composition according to claim 1, wherein at least one nitrogen atom is covalently bonded to an alkyl chain derived from a fatty acid.

10. An anaerobically curable composition according to claim 1, wherein at least one nitrogen atom is a secondary amine.

11. An anaerobically curable composition according to claim 1, wherein at least one nitrogen atom is a tertiary amine.

12. An anaerobically curable composition according to claim 1, wherein the stabilizer has only 4 carboxy groups.

13. An anaerobically curable composition according to claim 1, wherein the stabilizer comprises a glycinate group.

14. An anaerobically curable composition according to claim 1, wherein the at least one aliphatic chain comprises at least one unsaturated carbon-carbon bond.

15. An anaerobically curable composition according to claim 1, wherein the stabilizer is a compound having the formula: ##STR00016## wherein R.sup.1 is a C.sub.6-C.sub.50 an aliphatic chain, R.sup.2 is H or CH.sub.2C(O)OM, n is from 2 to 10, each M which may be the same or different is independently selected from H, Li, Na, K, Rb or Cs, wherein the compound of formula (I) comprises at least 3 nitrogen atoms and at least 4 carboxy groups.

16. An anaerobically curable composition according to claim 15, wherein R.sup.1 is a C.sub.6-C.sub.20 alkyl chain.

17. An anaerobically curable composition according to claim 15, wherein R.sup.1 is optionally substituted with one or more of NH.sub.2, HNR.sup.2, or N(R.sup.2).sub.2.

18. An anaerobically curable composition according to claim 15 wherein n is from 2 to 4.

19. An anaerobically curable composition according to claim 1, wherein the stabilizer is sodium cocoamphopolycarboxyglycinate.

20. An anaerobically curable composition according to claim 1, wherein the stabilizer is sodium tallowamphopolycarboxyglycinate.

21. An anaerobically curable composition according to claim 1, wherein the stabilizer is sodium oleylamphopolycarboxyglycinate.

22. An anaerobically curable composition according to claim 1, wherein the methacrylate component is a (meth)acrylate monomer having the formula:
H.sub.2C=CGCO.sub.2R.sup.8, wherein G may be hydrogen, halogen or alkyl groups having from 1 to 4 carbon atoms, and R.sup.8 may be selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl or aryl groups having from 1 to 16 carbon atoms, any of which may be optionally substituted or interrupted as the case may be with silane, silicon, oxygen, halogen, carbonyl, hydroxyl, ester, carboxylic acid, urea, urethane, polyurethane, carbonate, amine, amide, sulfur, sulfonate, and sulfone.

23. The cure product of a composition according to claim 1.

24. A method of bonding together two substrates comprising the steps of: applying a (meth)acrylate composition according to claim 1, to at least one of the substrates and mating together the substrates for a time sufficient to permit an adhesive bond to form from the (meth)acrylate composition between the mated substrates.

25. An assembly comprising two substrates bonded together by the cure product of composition according to claim 1.

26. A method of anaerobically curing a (meth)acrylate composition comprising the steps of: (a) providing a (meth)acrylate composition comprising: (i) a (meth)acrylate component; (ii) a cure inducing component; and (iii) at least one stabilizer comprising: at least one aliphatic chain, derived from a fatty acid, said stabilizer further comprising at least 2 nitrogen atoms and at least 4 carboxy groups; and (b) exposing the (meth)acrylate composition to an anaerobic environment for a time sufficient to cure the composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings in which:

(2) FIGS. 1-3 show the results for shear strength testing of control and test adhesive compositions which were heat aged at 35 C. for up to 10 weeks based on a pin and collar bonded test assembly.

DETAILED DESCRIPTION OF THE INVENTION

(3) It should be readily apparent to one of ordinary skill in the art that the examples disclosed herein below represent illustrative examples only, and that other arrangements and methods capable of reproducing the invention are possible and are embraced by the present invention.

(4) Stabilizers of the present invention are defined above. Such stabilizers are available under the trade name Ampholak, from Akzo Nobel.

(5) Stabilisers A-C below contain the following constituents in the noted amounts, as reported by the manufacturer.

(6) TABLE-US-00001 Composition Chemical Name % (w/w) Classification AMPHOLAK Stabilizer composition A 7CX/C Water 60-100 Non-Hazardous Sodium Chloride 0-20 Non-Hazardous Sodium 20-40 Non-Hazardous cocoamphopolycarboxyglycinate AMPHOLAK Stabilizer composition B 7TX Water 60-100 Non-Hazardous Sodium Chloride 0-20 Non-Hazardous Sodium 20-40 N; R50 Tallowamphopolycarboxyglycinate AMPHOLAK Stabilizer composition C XO7/C Water 60-100 Non-Hazardous Sodium Chloride 0-20 Non-Hazardous Sodium 20-40 Non-Hazardous Oleylamphopolycarboxyglycinate

(7) As a control sample EDTA was employed as stabilizer a 3.5% solution in a 3/1 propylene glycol/water mix.

(8) Advantageously, the above stabilizers act as chelators, sequestering metal ions thereby preventing pre-mature cure of anaerobically curable (meth)acrylate compositions comprising said stabilizers. They therefore provide for greater storage stability.

(9) The pin-and-collar test was used to compare shear strengths of adhesive compositions comprising the stabilizer of the invention to adhesive compositions comprising EDTA. The pin-and-collar test was carried in accordance with ISO 10123.

(10) The composition details are outlined below:

(11) 100 g batches of test composition were prepared from the listed components in the noted amounts as set forth below by weight percent.

(12) TABLE-US-00002 % weight of total Components Identity composition (meth)acrylate component polyurethane methacrylate 79.84 resin 3-(Trimethoxysilyl)-propyl 0.95 methacrylate PEG 200 dimethacrylate 3.10 Hydroxylpropyl methacrylate 2.99 Acrylic acid Acrylic acid 8.69 Cure inducing component Cumene hydroperoxide 1.95 1-Acetyl-2-phenylhydrazine 0.97 Saccharin 0.34 Stabilizers 5% naphthoquinone solution 0.20 (w/w in polyethylene glycol dimethacrylate) 9.2% chelator solution** 0.97 (w/w) **for test samples, the chelator solution was an Ampholak solution selected from Ampholak 7CX/C, Ampholak 7TX, and Ampholak XO7/C; for control samples, the chelator solution was an EDTA solution

(13) Initially the compositions were prepared by adding with mechanical mixing at room temperature in the appropriate amounts of the components as noted.

(14) The components were mixed for an appropriate period to allow for dissolution and/or dispersion, as the case may be of the solid components. The so-formed formulations were stored for further use by covering the beaker ensuring that an air pocket remained between the surface of the formulation and the cover.

(15) The control sample is the same as the test sample, albeit an EDTA solution replaces the chelator solution of the test sample which comprises the chelators of the invention.

(16) The formulations in accordance with this invention show shelf-stability at room temperature in open containers over time.

(17) The thermal stability of test compositions were compared to control compositions at 82 C. Test compositions comprising the stabilizers of the invention gave the same 82 C. thermal stability as control compositions comprising EDTA at the same weight percent. High thermal stability is particularly desirable, for applications in, for example, engine fittings, whereby elevated temperatures are experienced.

(18) Compositions were heat aged at 35 C. for up to 10 weeks. Control and test adhesive compositions, each aged for a given time period, were applied to the pin-and-collar specimen and allowed to cure for a fixed time period. The shear strength was then assessed and the results are shown in FIGS. 1 to 3. The stabilizer of the present invention present in the test sample for FIGS. 1 to 3 is Ampholak X07/C.

(19) FIG. 1 shows the results for shear strength assessment of control and test samples after curing at room temperature for 15 minutes and ageing at 35 C. for the specified number of weeks. The shear strength for both the control composition and the test composition was comparable after 8 weeks.

(20) Shear strength pin-and-collar test results after curing for 15 minutes at room temperature (see FIG. 1) and ageing at 35 C. for the specified number of weeks.

(21) TABLE-US-00003 Time (Weeks) 0 2 4 6 8 10 Control @ 35 C. 6 7 6 3 2 2 (N/mm.sup.2) Test @ 35 C. 5 5 7 5 2 2 (N/mm.sup.2)

(22) FIG. 2 shows the results for shear strength assessment of control and test samples after curing at room temperature for 1 hour and heat ageing for the specified number of weeks. The results clearly indicate comparable shear strength for both the control composition and the test composition.

(23) Shear strength pin-and-collar test results after curing for 1 hour at room temperature and heat ageing for the specified number of weeks (see FIG. 2).

(24) TABLE-US-00004 Time (Weeks) 0 2 4 6 8 10 Control @ 35 C. 16 15 12 8 10 10 (N/mm.sup.2) Test @ 35 C. 15 12 11 9 9 10 (N/mm.sup.2)

(25) FIG. 3 shows the results for shear strength assessment of control and test samples after curing for 24 hours at room temperature and heat ageing at 35 C. for the specified number of weeks. The results clearly indicate comparable shear strength for both the control composition and the test composition.

(26) Shear strength pin-and-collar test results after curing for 24 hours at room temperature and heat ageing at 35 C. for the specified number of weeks (see FIG. 3).

(27) TABLE-US-00005 Time (Weeks) 0 2 4 6 8 10 Control @ 35 C. 26 23 22 22 25 26 (N/mm.sup.2) Test @ 35 C. 25 20 21 19 22 24 (N/mm.sup.2)

(28) Desirably, stabilizers having the following formula:

(29) ##STR00015##
wherein R.sup.1 is a C.sub.6-C.sub.50 aliphatic chain,
R.sup.2 is H or CH.sub.2C(O)OM, n is from 2 to 10,
each M which may be the same or different is independently selected from H, Li, Na, K, Rb or Cs,
and wherein the compound of formula (I) comprises at least 3 nitrogen atoms and at least 4 carboxy groups;
proved to be at least as effective chelators as EDTA in the compositions of the present invention.

(30) Compositions comprising at least one of sodium cocoamphopolycarboxyglycinate, sodium tallowamphopolycarboxyglycinate, and/or sodium oleylamphopolycarboxyglycinate are particularly desirable.

(31) Overall, the stabilizer of the present invention is a viable alternative to EDTA as a chelator in anaerobically curable compositions. Advantageously, anaerobically curable adhesive compositions comprising the stabilizer of the present invention, demonstrated comparative shear strengths to compositions wherein EDTA was used as a chelator.

(32) 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.

(33) 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.