Cyanoacrylate compositions

Abstract

Allyl-cyanoacrylate-containing compositions with an anhydride aromatic component, which when cured confers improved moisture resistance, are provided.

Claims

1. A cyanoacrylate adhesive composition, comprising: (a) a cyanoacrylate component comprising allyl-2-cyanoacrylate and another cyanoacrylate monomer, and (b) in an amount up to about 1% by weight based on the total composition, an aromatic anhydride component selected from the group consisting of phthalic anhydride, 4,4′-(4,4′-isopropylidone diphenoxy)bis(phthalic anhydride), and combinations thereof, wherein said allyl-2-cyanoacrylate is present in an amount of at least 40% by weight, based on the cyanoacrylate component.

2. The composition of claim 1, further comprising an acidic stabilizer and a free radical inhibitor.

3. The composition according to claim 1, wherein the another cyanoacrylate monomer is (a) represented by H.sub.2C═C(CN)—COOR, wherein R is selected from C.sub.1-15 alkyl, alkoxyalkyl, cycloalkyl, alkenyl, aralkyl, aryl and haloalkyl groups, or (b) a biscyanoacrylate.

4. The composition according to claim 1, further comprising an accelerator component selected from the group consisting of calixarene, oxacalixarene, silacrown, cyclodextrin, crown ether, poly(ethyleneglycol) di(meth)acrylate, ethoxylated hydric compound, and combinations thereof.

5. The composition according to claim 4, wherein the crown ether is selected from members within the group consisting of 15-crown-5, 18-crown-6, dibenzo-18-crown-6, benzo-15-crown-5-dibenzo-24-crown-8, dibenzo-30-crown-10, tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8, cyclohexyl-12-crown-4, 1,2-decalyl-15-crown-5, 1,2-naphtho-15-crown-5, 3,4,5-naphtyl-16-crown-5, 1,2-methyl-benzo-18-crown-6, 1,2-methylbenzo-5, 6-methylbenzo-18-crown-6, 1,2-t-butyl-18-crown-6, 1,2-vinylbenzo-15-crown-5, 1,2-vinylbenzo-18-crown-6, 1,2-t-butyl-cyclonexyl-18-crown-6, asym-dibenzo-22-crown-6, and 1,2-benzo-1,4-benzo-5-oxygen-20-crown-7 and combinations thereof.

6. Reaction products of the composition according to claim 1.

7. The composition according to claim 1, wherein said allyl-2-cyanoacrylate is present in an amount of up to about 90% by weight of the cyanoacrylate component.

8. The composition according to claim 1, wherein cured products of which show improved moisture resistance at a temperature of 65° C. and 95% relative humidity.

9. A cyanoacrylate adhesive composition, comprising (a) a cyanoacrylate component comprising allyl-2-cyanoacrylate and another cyanoacrylate monomer, (b) an aromatic anhydride component selected from the group consisting of phthalic anhydride, 4,4′-(4,4′-isopropylidone diphenoxy)bis(phthalic anhydride), and combinations thereof, and (c) a hydrogenated aromatic anhydride component, wherein said allyl-2-cyanoacrylate is present in an amount of at least 50% by weight, based on the cyanoacrylate component.

10. The composition according to claim 9, wherein cured products of which show improved moisture resistance at a temperature of 65° C. and 95% relative humidity.

11. A cyanoacrylate adhesive composition, comprising: (a) a cyanoacrylate component comprising in an amount of at least 40% by weight, allyl-2-cyanoacrylate, and in an amount of at least 60% by weight, ethyl-2-cyanoacrylate, each based on the total cyanoacrylate component, and (b) in an amount of about 0.5% by weight, phthalic anhydride, based on the total composition.

12. The composition according to claim 11, wherein cured products of which show improved moisture resistance at a temperature of 65° C. and 95% relative humidity.

13. The composition according to claim 11, wherein said allyl-2-cyanoacrylate is present in an amount of at least 40% by weight to about 90% by weight.

14. A method of bonding together two substrates, comprising the steps of: applying a cyanoacrylate adhesive composition according to claim 1, to at least one of the substrates; and mating together the substrates for a time sufficient to permit the adhesive to fixture.

15. A method of preparing a cyanoacrylate adhesive composition according to claim 1, comprising the steps of: providing allyl-2-cyanoacrylate and another cyanoacrylate, and combining therewith with mixing an aromatic anhydride component.

16. A method of improving moisture resistance at a temperature of 65° C. and 95% relative humidity of cured cyanoacrylate compositions on assemblies having at least one substrate constructed from steel, comprising the steps of: applying a cyanoacrylate adhesive composition according to claim 1, to at least one of the substrates; mating together the substrates for a time sufficient to permit the cyanoacrylate adhesive composition to fixture and form assemblies; and exposing the assemblies to a temperature of 65° C. and 95% relative humidity.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows bond strength on mild steel substrates (at a temperature of 40° C. and 98% relative humidity) of ethyl-2-cyanoacrylate with and without anhydride additives, and allyl-2-cyanoacrylate with anhydride additives.

(2) FIG. 2 shows bond strength on mild steel substrates (at a temperature of 65° C. and 95% relative humidity) of ethyl-2-cyanoacrylate with anhydride additives, and allyl-2-cyanoacrylate.

(3) FIG. 3 shows bond strength over time (in weeks) under a temperature of 65° C. and 95% relative humidity of multiple cyanoacrylate compositions on mild steel substrates.

(4) FIG. 4 shows bond strength over time (in weeks) under a temperature of 40° C. and 98% relative humidity of multiple cyanoacrylate compositions containing varying levels of allyl and ethyl cyanoacrylate on mild steel substrates.

(5) FIG. 5 shows bond strength over time (in weeks) under a temperature of 65° C. and 95% relative humidity of multiple cyanoacrylate compositions containing varying levels of allyl and ethyl cyanoacrylate on mild steel substrates.

DETAILED DESCRIPTION

(6) As noted above, this invention is directed to a cyanoacrylate composition, which when cured confers improved moisture resistance. The cyanoacrylate composition includes (a) an allyl-cyanoacrylate and (b) an anhydride component.

(7) The allyl-2-cyanoacrylate should be included in the compositions in an amount within the range of from about 50% to about 99.98% by weight, with the range of about 90% to about 99% by weight being desirable, and about 95% by weight of the total composition being particularly desirable.

(8) Beyond the allyl-2-cyanoacrylate, the cyanoacrylate composition may also include other cyanoacrylate monomers, such as those represented by H.sub.2C═C(CN)—COOR, where R is selected from C.sub.1-15 alkyl, alkoxyalkyl, cycloalkyl, alkenyl, aralkyl, aryl, and haloalkyl groups. Desirably, the cyanoacrylate monomer is selected from methyl cyanoacrylate, ethyl-2-cyanoacrylate, propyl cyanoacrylates, butyl cyanoacrylates (such as n-butyl-2-cyanoacrylate), octyl cyanoacrylates, β-methoxyethyl cyanoacrylate and combinations thereof. Bis-cyanoacrylate may also be included.

(9) The aromatic anhydride component may be any aromatic anhydride, though phthalic anhydride or 4,4′-(4,4′-isopropylidone diphenoxy)bis(phthalic anhydride), are desirable.

(10) In addition to the aromatic anhydride component, hydrogenated or partially hydrogenated aromatic anhydrides may also be included. An example of a hydrogenated aromatic anhydride is a hydrogenated phthalic anhydride, such as 3,4,5,6-tetrahydrophthalic anhydride. Isomeric versions thereof and partially hydrogenated versions of phthalic anhydride may also be used.

(11) The aromatic anhydride component should be used in an amount up to about 1% by weight, such as within the range of about 0.05 to about 0.5% by weight.

(12) Accelerators may also be included in the inventive cyanoacrylate compositions, such as any one or more selected from calixarenes and oxacalixarenes, silacrowns, crown ethers, cyclodextrins, poly(ethyleneglycol) di(meth)acrylates, ethoxylated hydric compounds and combinations thereof.

(13) Of the calixarenes and oxacalixarenes, many are known, and are reported in the patent literature. See e.g. U.S. Pat. Nos. 4,556,700, 4,622,414, 4,636,539, 4,695,615, 4,718,966, and 4,855,461, the disclosures of each of which are hereby expressly incorporated herein by reference.

(14) For instance, as regards calixarenes, those within the following structure are useful herein:

(15) ##STR00001##
where R.sup.1 is alkyl, alkoxy, substituted alkyl or substituted alkoxy; R.sup.2 is H or alkyl; and n is 4, 6 or 8.

(16) One particularly desirable calixarene is tetrabutyl tetra[2-ethoxy-2-oxoethoxy]calix-4-arene.

(17) A host of crown ethers are known. For instance, examples which may be used herein either individually or in combination, include 15-crown-5, 18-crown-6, dibenzo-18-crown-6, benzo-15-crown-5-dibenzo-24-crown-8, dibenzo-30-crown-10, tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8, cyclohexyl-12-crown-4, 1,2-decalyl-15-crown-5, 1,2-naphtho-15-crown-5, 3,4,5-naphtyl-16-crown-5, 1,2-methyl-benzo-18-crown-6, 1,2-methylbenzo-5, 6-methylbenzo-18-crown-6, 1,2-t-butyl-18-crown-6, 1,2-vinylbenzo-15-crown-5, 1,2-vinylbenzo-18-crown-6, 1,2-t-butyl-cyclohexyl-18-crown-6, asym-dibenzo-22-crown-6 and 1,2-benzo-1,4-benzo-5-oxygen-20-crown-7. See U.S. Pat. No. 4,837,260 (Sato), the disclosure of which is hereby expressly incorporated herein by reference.

(18) Of the silacrowns, again many are known, and are reported in the literature.

(19) Specific examples of silacrown compounds useful in the inventive compositions include:

(20) ##STR00002##
dimethylsila-11-crown-4;

(21) ##STR00003##
dimethylsila-14-crown-5;

(22) ##STR00004##
and dimethylsila-17-crown-6.
See e.g. U.S. Pat. No. 4,906,317 (Liu), the disclosure of which is hereby expressly incorporated herein by reference.

(23) Many cyclodextrins may be used in connection with the present invention. For instance, those described and claimed in U.S. Pat. No. 5,312,864 (Wenz), the disclosure of which is hereby expressly incorporated herein by reference, as hydroxyl group derivatives of an α, β or γ-cyclodextrin would be appropriate choices as an accelerator component.

(24) For instance, poly(ethylene glycol) di(meth)acrylates suitable for use herein include those within the following structure:

(25) ##STR00005##
where n is greater than 3, such as within the range of 3 to 12, with n being 9 as particularly desirable. More specific examples include PEG 200 DMA, (where n is about 4) PEG 400 DMA (where n is about 9), PEG 600 DMA (where n is about 14), and PEG 800 DMA (where n is about 19), where the number (e.g., 400) represents the average molecular weight of the glycol portion of the molecule, excluding the two methacrylate groups, expressed as grams/mole (i.e., 400 g/mol). A particularly desirable PEG DMA is PEG 400 DMA.

(26) And of the ethoxylated hydric compounds (or ethoxylated fatty alcohols that may be employed), appropriate ones may be chosen from those within the following structure:

(27) ##STR00006##
where C.sub.m can be a linear or branched alkyl or alkenyl chain, m is an integer between 1 to 30, such as from 5 to 20, n is an integer between 2 to 30, such as from 5 to 15, and R may be H or alkyl, such as C.sub.1-6 alkyl.

(28) When used, the accelerator embraced by the above structures should be included in the compositions in an amount within the range of from about 0.01% to about 10% by weight, with the range of about 0.1 to about 0.5% by weight being desirable, and about 0.4% by weight of the total composition being particularly desirable.

(29) A stabilizer package is also ordinarily found in cyanoacrylate compositions. The stabilizer package may include one or more free radical stabilizers and anionic stabilizers, each of the identity and amount of which are well known to those of ordinary skill in the art. See e.g. U.S. Pat. Nos. 5,530,037 and 6,607,632, the disclosures of each of which are hereby incorporated herein by reference.

(30) Other additives may be included in the inventive cyanoacrylate compositions, such as certain acidic materials (like citric acid), thixotropy or gelling agents, rubber tougheners, thickeners, dyes, and combinations thereof.

(31) In another aspect of the invention, there is provided a method of bonding together two substrates, which method includes applying to at least one of the substrates a composition as described above, and thereafter mating together the substrates for a time sufficient to permit the adhesive to fixture. For many applications, the substrate should become fixed by the inventive compositions in less than about 150 seconds, and depending on the substrate as little as about 30 seconds.

(32) In yet another aspect of the invention, there are provided cured reactive products of the so-described compositions.

(33) In still another aspect of the invention, there is provided a method of preparing the so-described compositions.

(34) The invention will be further illustrated by the examples which follow.

EXAMPLES

(35) All samples were prepared by mixing together the noted constituents for a sufficient period of time to ensure substantial homogeneity of the constituents. Ordinarily, about 30 minutes should suffice, depending of course on the quantity of the constituents used.

(36) Initially, a variety of aromatic and hydrogenated anhydrides were evaluated in ethyl cyanoacrylate compositions, each containing 6.5 percent by weight of PMMA, 0.1 percent by weight of a crown ether, and 7 ppm of BF.sub.3, to form Samples B-E (with Sample A without an anhydride used as a control). The formulation details are set forth below in Table 1.

(37) TABLE-US-00001 TABLE 1 Constituents Sample/(Amt/wt %) Type Identity A B C D CA Ethyl CA 92.82 92.73 92.32 92.55 Anhydride Phthalic — 0.09 0.5 0.09 Anhydride 4,4′-(4,4′- — — — 0.09 isopropylidone diphenoxy)bis (phthalic anhydride) 3,4,5,6- — — — 0.09 tetrahydro- phthalic anhydride

(38) A variety of aromatic and hydrogenated aromatic anhydrides were also evaluated in an allyl cyanoacrylate composition (“Allyl CA” or “ACA”), each containing 6.5 percent by weight of PMMA, 0.1 percent by weight of a crown ether, and 7 ppm of BF.sub.3, to form Samples F-J. Sample E is used as a control. The formulation details are set forth in Table 2.

(39) TABLE-US-00002 TABLE 2 Constituents Sample/(Amt/wt %) Type Identity E F G H I J CA Allyl CA 93.40 93.40 93.40 93.40 93.40 93.40 Anhydride Phthalic —  0.09 0.09 0.5 Anhydride 4,4′-(4,4′- — — —  0.09 0.09 isopropylidone diphenoxy)bis (phthalic anhydride) 3,4,5,6-tetra- —  0.09 — 0.09 hydro-phthalic anhydride

(40) Tables 3-5 capture bond strength maintenance over time for mild steel lap shear assemblies at 98% or 95% relative humidity and a temperature of either 40° C. or 65° C. Reference to FIGS. 1-3 shows this data graphically.

(41) Next, allyl cyanoacrylate and ethyl cyanoacrylate (“Ethyl CA” or “ECA”) were used individually and in combination in increments of 10 parts, increasing or decreasing as shown in Table 6. PMMA at 6.5 parts, 0.1 percent by weight of a crown ether, 7 ppm of BF.sub.3 and phthalic anhydride at 0.5 parts were also used in each of the samples.

(42) Table 3 shows bond strength data generated over time on mild steel lap shear assemblies. With reference to FIG. 1, it is seen that the addition of 0.5% phthalic anhydride to the allyl cyanoacrylate composition (Sample J) significantly outperforms its counterpart ethyl cyanoacrylate composition (Sample C). Similar observations were made when comparing the addition of all three anhydrides to the allyl cyanoacrylate composition (Sample I) and the ethyl cyanoacrylate composition (Sample D). Table 4 shows bond strength data generated over time on mild steel substrates. With reference to FIG. 2, it is seen that the addition of all three anhydrides at levels of less than 0.09% to the allyl cyanoacrylate composition (Sample I) significantly outperform the counterpart ethyl cyanoacrylate composition (Sample D). Table 5 shows bond strength data generated over time on mild steel substrates. With reference for FIG. 3, it is seen that the addition of any of the anhydrides to the allyl cyanoacrylate compositions—Samples F, H, I and J—significantly outperform the counterpart ethyl cyanoacrylate compositions.

(43) TABLE-US-00003 TABLE 3 Time (weeks)/Mpas Sample 0 1 2 4 A 12.6 7.6 6.4 5.7 C 13.7 8.0 6.6 6.6 J 16.4 12.5 14.9 15.5 D 16.0 10.4 9.4 7.8 I 15.6 14.8 15.6 19.1

(44) TABLE-US-00004 TABLE 4 Time (weeks)/Mpas Sample 0 1 2 4 A 12.6 5.6 5.1 4.5 C 13.7 9.0 9.2 4.6 J 16.4 20.0 18.5 16.5 D 16.0 9.3 7.7 4.4 I 15.6 24.6 24.3 19.3

(45) TABLE-US-00005 TABLE 5 Time (weeks)/Mpas Sample 0 1 2 4 F 14.2 10.3 15.5 15.9 H 14.4 11.1 10.1 12.2 G 15.2 8.6 7.5 8.7 I 15.6 14.8 15.6 19.1 E 16.4 7.3 5.6 6.1 LOCTITE 401 8.1 7.9 5.7 5.4 J 16.4 12.5 14.9 15.5

(46) TABLE-US-00006 TABLE 6 Sample No. ACA ECA 1 0 100 2 0 100 3 10 90 4 20 80 5 30 70 6 40 60 7 50 50 8 60 40 9 70 30 10 80 20 11 90 10 12 100 0 13 100 0

(47) Each of Sample Nos. 1-13 was applied to mild steel lap shears, and bonded assemblies prepared for moisture performance evaluation. Tables 7 and 8 capture bond strength maintenance over time for steel lap shear assemblies at 98% or 95% relative humidity and either 40° C. or 65° C. The data shown in Table 7 may be seen graphically with reference to FIG. 4; the data shown in Table 8 may be seen graphically with reference to FIG. 5.

(48) TABLE-US-00007 TABLE 7 Time (weeks)/Mpas Sample No. 0 1 2 4 1 12.7 7.6 6.4 5.7 2 13.7 8.0 6.6 6.6 3 15.4 8.1 9.8 8.2 4 15.2 9.5 10.1 8.8 5 17.8 9.7 11.7 9.1 6 18.2 11.6 14.3 10.2 7 18.2 12.3 19.4 13.2 8 16.9 13.0 19.9 13.7 9 18.5 14.9 21.6 16.1 10 16.3 15.2 21.7 21.9 11 17.9 16.5 24.6 20.1 12 16.4 19.5 16.6 17.3 13 16.4 7.3 5.6 6.1

(49) TABLE-US-00008 TABLE 8 Time (weeks)/Mpas Sample No. 0 1 2 4 1 12.7 5.6 5.1 4.5 2 13.7 9.0 9.2 4.61 3 15.4 12.0 8.6 6.5 4 15.2 13.5 9.7 6.6 5 17.8 13.9 9.7 8.8 6 18.2 17.4 9.9 8.5 7 18.2 21.5 13.8 9.9 8 16.9 21.8 12.9 14.1 9 18.5 23.4 16.5 17.3 10 16.3 22.5 18.9 17.6 11 17.9 26.3 18.7 20.8 12 16.4 23.6 21.7 20.0 13 16.4 8.3 7.1 8.0

(50) With reference to FIGS. 4 and 5, it is seen that the allyl cyanoacrylate/anhydride compositions out perform the ethyl cyanoacrylate/anhydride compositions, particularly when one views data generated from compositions where the level of allyl cyanoacrylate is greater than or equal 40% by weight of the total composition.