阅读说明：本技术 柔性可光固化氰基丙烯酸酯组合物 (Flexible photocurable cyanoacrylate compositions ) 是由 L·李 X·魏 S·T·阿塔瓦拉 于 2020-04-05 设计创作，主要内容包括：本发明涉及一种可光固化组合物,其包括氰基丙烯酸酯组分、茂金属组分、光引发剂组分和增塑剂组分,其反应产物尤其在断裂伸长率方面表现出改善的柔韧性。(The present invention relates to a photocurable composition comprising a cyanoacrylate component, a metallocene component, a photoinitiator component and a plasticizer component, the reaction product of which exhibits improved flexibility, especially in terms of elongation at break.)

1. A cyanoacrylate composition comprising:

(a) a cyanoacrylate component;

(b) a metallocene component;

(c) a photoinitiator component; and

(d) a plasticizer component.

2. The composition of claim 1 wherein the plasticizer component is a short chain alkylene compound having a plurality of alkyl ester and/or reverse alkyl ester substituents thereon.

3. The composition of claim 1 wherein the plasticizer component is a short chain alkylene compound having 3 or 4 carbon atoms in the chain.

4. The composition of claim 1 wherein the plasticizer component is a short chain alkylene compound having a straight chain.

5. The composition of claim 1 wherein the plasticizer component is a short chain alkylene compound having 2-4 substituents thereon.

6. The composition of claim 1 wherein the plasticizer component is a short chain alkylene compound having a plurality of alkyl and/or retro-alkyl ester substituents thereon, wherein the alkyl and/or retro-alkyl ester has C_1-3Alkyl esters and/or reverse alkyl esters.

7. The composition of claim 1, wherein the plasticizer component is selected from the group consisting of:

8. the composition of claim 1, wherein the plasticizer component is present in an amount of from about 10% to about 30% by weight.

9. The composition of claim 1, wherein the plasticizer component is present in an amount of from about 15% to about 35% by weight.

10. The composition of claim 1, wherein the plasticizer component is present in an amount of from about 15% to about 20% by weight.

11. The composition of claim 1, further comprising a stabilizer.

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

13. The composition of claim 1, further comprising an accelerator component.

14. The composition of claim 13, wherein the accelerator component is selected from the group consisting of: calixarenes, oxacalixarenes, silacrown ethers, cyclodextrins, crown ethers, poly (ethylene glycol) di (meth) acrylates, ethoxylated hydroxyl-containing compounds, and combinations thereof.

15. The composition of claim 1, further comprising an additive selected from the group consisting of: toughening agents, anti-shock additives, thixotropy imparting agents, thickeners, dyes, and combinations thereof.

16. The reaction product of the composition of claim 1.

17. The composition of claim 1, wherein the reaction product thereof exhibits substantially no phase separation.

18. The composition of claim 1, wherein the reaction product thereof exhibits an elongation at break of greater than about 35%.

19. The composition of claim 1, wherein the reaction product thereof exhibits an elongation at break of greater than about 125%.

20. The composition of claim 1, wherein the reaction product thereof exhibits an overall shear strength on polycarbonate of greater than about 1800 psi.

21. The composition of claim 1, wherein the reaction product thereof exhibits an overall shear strength on polycarbonate of greater than about 1900 psi.

22. The composition of claim 1, wherein the reaction product thereof exhibits an overall shear strength on polycarbonate of greater than about 2200 psi.

23. The composition of claim 1, wherein the reaction product thereof exhibits greater than about 60 cycles in an oscillatory test.

24. A method of bonding two substrates together, wherein at least one substrate is comprised of a thermoplastic material, said method comprising the steps of:

applying a cyanoacrylate composition according to claim 1 to at least one substrate, and

the substrates are mated together for a sufficient time to allow the adhesive to set.

Technical Field

The present invention relates to a photocurable composition comprising a cyanoacrylate component, a metallocene component, a photoinitiator component and a plasticizer component, the reaction product of which exhibits improved flexibility, especially in terms of elongation at break.

Brief description of the related art

Cyanoacrylate adhesive compositions are well known and are widely used as quick setting, instant adhesives having a variety of uses. See H.V.Coover, D.W.Dreifus and J.T.O' Connor, "cyanoacrylates Adhesives" in Handbook of Adhesives,27,463-77, I.Skeist, ed., Van Nostrand Reinhold, New York,3rd ed. (1990). See also G.H.Millet, "Cyanoacrylate Adhesives" in Structural Adhesives, Chemistry and Technology, S.R.Hartshorn, ed., plenum Press, New York, p.249-307 (1986).

Cyanoacrylate compositions generally tend to cure to form relatively brittle polymeric materials. This is an undesirable property for certain applications where a certain degree of flexibility is required in the polymer material. Such applications include bonding flexible materials where a degree of flexibility is required in the bonding to match the flexibility of the material. There is also a need for flexible polymeric materials in applications where the polymeric material may be subjected to different forces in its end use application. For example, if the polymeric material has bonded two substrates together, the substrates may not remain undisturbed but may be subjected to external forces, e.g., the substrates form part of a moving object, or part of a stationary object, which is subjected to one or more continuous or incidental forces from other moving objects.

In the past, efforts have been made to improve the flexibility of the cured product of cyanoacrylate compositions. See, for example, U.S. patent nos. 2,776,232, 2,784,215, 2,784,127, 3,699,127, 3,961,966, 4,364,876, and 4,444,933. But are not suitable for photocurable cyanoacrylates, such as described in U.S. Pat. No. 5,922,783 (Wojciak).

The' 783 patent provides a photocurable composition comprising: (a) a 2-cyanoacrylate component, (b) a metallocene component, and (c) a photoinitiator component. There is no mention in the' 783 patent of including plasticizers or attempting to impart flexibility to the cured product of the disclosed photocurable compositions.

One way to overcome the brittleness of conventional polymerized cyanoacrylate adhesives is to plasticize the composition by using a mixture of monomers. It is believed that the use of cyanoacrylate monomer mixtures results in a more flexible polymeric material when the monomer mixture is cured. The second approach is to incorporate plasticizers into cyanoacrylate compositions. Flexibility here is generally obtained at the expense of cure speed and/or bond strength.

U.S. patent No. 6,977,278(Misiak) describes specific cyanoacrylate compositions comprising: (i) at least one lower cyanoacrylate monomer component selected from the group consisting of ethyl cyanoacrylate and ethyl methoxycyanoacrylate; (ii) at least one higher cyanoacrylate monomer component in an amount greater than 12% by weight, based on the total weight of the combination of lower cyanoacrylate monomers and higher cyanoacrylate monomers, and selected from the group consisting of: n-propyl cyanoacrylate, isopropyl cyanoacrylate, n-butyl cyanoacrylate, sec-butyl cyanoacrylate, isobutyl cyanoacrylate, tert-butyl cyanoacrylate, n-pentyl cyanoacrylate, 1-methyl-butyl cyanoacrylate, 1-ethyl-propyl cyanoacrylate, neopentyl cyanoacrylate, n-hexyl cyanoacrylate, 1-methyl pentyl cyanoacrylate, n-heptyl cyanoacrylate, n-octyl cyanoacrylate, n-nonyl cyanoacrylate, n-decyl cyanoacrylate, n-undecyl cyanoacrylate, n-dodecyl cyanoacrylate, cyclohexyl cyanoacrylate, benzyl cyanoacrylate, phenyl cyanoacrylate, tetrahydrofurfuryl cyanoacrylate, allyl cyanoacrylate, propargyl cyanoacrylate, 2-butenyl cyanoacrylate, phenethyl cyanoacrylate, butyl cyanoacrylate, isobutyl cyanoacrylate, butyl cyanoacrylate, 1-methyl methacrylate, butyl cyanoacrylate, n-octyl cyanoacrylate, n-nonyl cyanoacrylate, n-decyl cyanoacrylate, n-pentyl cyanoacrylate, n-heptyl cyanoacrylate, n-pentyl acrylate, n-pentyl cyanoacrylate, n-pentyl acrylate, n-heptyl cyanoacrylate, n-pentyl acrylate, n-octyl cyanoacrylate, n-pentyl acrylate, n-octyl cyanoacrylate, n-pentyl acrylate, n-octyl cyanoacrylate, n-octyl acrylate, n-pentyl acrylate, n-octyl acrylate, n-pentyl acrylate, n-octyl acrylate, n-pentyl acrylate, n-butyl acrylate, n-octyl acrylate, n-butyl acrylate, n, Chloropropyl cyanoacrylate, ethoxyethyl cyanoacrylate, ethoxypropyl cyanoacrylate, ethoxyisopropyl cyanoacrylate, propoxyethyl cyanoacrylate, isopropoxyethyl cyanoacrylate, butoxyethyl cyanoacrylate, methoxypropyl cyanoacrylate, methoxyisopropyl cyanoacrylate, methoxybutyl cyanoacrylate, propoxymethyl cyanoacrylate, propoxyethyl cyanoacrylate, propoxypropyl cyanoacrylate, butoxymethyl cyanoacrylate, butoxyethyl cyanoacrylate, butoxypropyl cyanoacrylate, butoxyisopropyl cyanoacrylate, butoxybutyl cyanoacrylate, isononyl cyanoacrylate, isodecyl cyanoacrylate, cyclohexylmethyl cyanoacrylate (cyclohexyl methyl-cyanoacrylate), naphthyl cyanoacrylate, 2- (2' -methoxy) -ethoxyethyl-cyanoacrylate, ethoxypropyl cyanoacrylate, isopropoxyethyl cyanoacrylate, propoxyethyl cyanoacrylate, propoxypropyl cyanoacrylate, butoxypropyl cyanoacrylate, butoxyisopropyl cyanoacrylate, butoxybutyl cyanoacrylate, isopropoxymethyl cyanoacrylate, isopropoxypropyl cyanoacrylate, cyclohexyl methyl cyanoacrylate, 2- (2' -ethoxy) -ethoxyethyl-cyanoacrylate, 2- (2' -propoxy) -ethoxyethyl-cyanoacrylate, 2- (2' -butoxy) -ethoxyethyl-cyanoacrylate, 2- (2' -pentyloxy) -ethoxyethyl-cyanoacrylate, 2- (2' -hexyloxy) -ethoxyethyl-cyanoacrylate, 2- (2' -methoxy) -propoxypropyl-cyanoacrylate, 2- (2' -ethoxy) -propoxypropyl-cyanoacrylate, 2- (2' -propoxy) -propoxypropyl-cyanoacrylate, 2- (2' -pentyloxy) -propoxypropyl-cyanoacrylate, 2- (2' -hexyloxy) -propoxypropyl-cyanoacrylate, 2- (2' -methoxy) -butoxybutyl-cyanoacrylate, 2- (2' -ethoxy) -butoxybutyl-cyanoacrylate, 2- (2' -butoxy) -butoxybutyl-cyanoacrylate, 2- (3' -methoxy) -propoxyethyl-cyanoacrylate, 2- (3' -methoxy) -butoxyethyl-cyanoacrylate, 2- (3' -methoxy) -propoxypropyl-cyanoacrylate, 2- (3' -methoxy) -butoxypropyl-cyanoacrylate, 2- (2' -methoxy) -ethoxypropyl-cyanoacrylate and 2- (2' -methoxy) -ethoxy, butyl-cyanoacrylate; (iii) at least one plasticizer component comprising at least one ester group-containing plasticizer, the plasticizer component being miscible in the mixture of component (i) and component (ii); the plasticizer component is present in the composition in an amount from about 15% to about 40% by weight of the composition and the Ap/Po ratio of the plasticizer component is in the range of from about 1 to less than about 6, provided that the plasticizer component does not include pentaerythritol tetrabenzoate as the sole plasticizer.

The' 278 patent clearly shows that amounts of plasticizer up to 12 wt% do not produce the desired properties, and that very large amounts of plasticizer adversely affect the cure speed and bond strength, so that if amounts less than about 40 wt% are used, it appears that the desired flexibility can be achieved in the cured composition.

More recently, U.S. patent No. 9,528,034(Li) describes and claims cyanoacrylate compositions comprising: (a) a cyanoacrylate component comprising a combination of ethyl 2-cyanoacrylate and octyl 2-cyanoacrylate; and (b) acetyl triethyl citrate in an amount from about 5 weight percent to less than about 15 weight percent. The' 034 patent does not mention that the teachings therein may be extended to photocurable cyanoacrylate compositions.

Despite the state of the art, there is a long-felt but unmet desire to obtain photocurable cyanoacrylate compositions that exhibit all of the attributes of photocurable cyanoacrylate compositions and add a degree of flexibility. It would therefore be highly advantageous to provide a solution to this desire.

Background

Disclosure of Invention

The present invention provides just such a solution.

In practice, the present invention provides photocurable compositions comprising a cyanoacrylate component (e.g., ethyl-2-cyanoacrylate), a metallocene component (e.g., ferrocene), a photoinitiator component (e.g., 2,4, 6-trimethylbenzoyldiphenylphosphine oxide), and a plasticizer component (e.g., a short chain alkylene compound having a plurality of alkyl esters and/or reverse alkyl esters substituted thereon).

Furthermore, the present invention relates to reaction products of the compositions of the present invention.

In addition, the present invention relates to a process for preparing the composition of the invention.

And to a method of bonding substrates using the composition of the invention.

The invention will be more fully understood upon reading the section entitled "detailed description" below.

Detailed Description

As mentioned above, the present invention is directed to a photocurable composition comprising a cyanoacrylate component, a metallocene component, a photoinitiator component and a plasticizer component.

The cyanoacrylate component includes cyanoacrylate monomers which may optionally have a number of substituents, for example H₂C ═ C (cn) -COOR, wherein R is selected from C_1-15Alkyl, alkoxyalkyl, cycloalkyl, alkenyl, aralkyl, aryl, allyl, and haloalkyl. Desirably, the cyanoacrylate monomer is selected from the group consisting of methyl cyanoacrylate, ethyl 2-cyanoacrylate, propyl cyanoacrylate, butyl cyanoacrylate, octyl cyanoacrylate, allyl 2-cyanoacrylate, β -methoxyethyl-2-cyanoacrylate, and combinations thereof. A particularly desirable cyanoacrylate monomer for use herein is ethyl-2-cyanoacrylate.

The cyanoacrylate component is present in an amount of about 65% to about 95% by weight, for example about 70% to about 85% by weight, desirably about 75% to about 80% by weight.

A variety of metallocenes are suitable for use herein. Those of particular interest herein can be represented by the metallocenes in structure I:

wherein R is₁And R₂May be the same or different, and may occur at least once and up to four times on each ring in the case of five-membered rings, and up to five times on each ring in the case of six-membered rings;

R₁and R₂Can be selected from H; any straight or branched alkyl component having from 1 to about 8 carbon atoms, e.g. CH₃、CH₂CH₃、CH₂CH₂CH₃、CH(CH₃)₂、C(CH₃)₃Etc.; acetyl; a vinyl group; an allyl group; a hydroxyl group; a carboxyl group; - (CH)₂)_n-OH, wherein n can be an integer ranging from 1 to about 8；-(CH₂)_n-COOR₃Wherein n can be an integer ranging from 1 to about 8 and R₃Can be any straight or branched chain alkyl moiety having from 1 to about 8 carbon atoms; h; li; na; or- (CH)₂)_n'Wherein n' may be an integer in the range of 2 to about 8; - (CH)₂)_n-OR₄Wherein n can be an integer ranging from 1 to about 8 and R₄Can be any straight or branched chain alkyl moiety having from 1 to about 8 carbon atoms; or- (CH)₂)_n-N⁺(CH₃)₃X^-Wherein n may be an integer ranging from 1 to about 8 and X may be Cl^-、Br^-、I^-、ClO₄ ^-Or BF₄ ^-；

Y₁And Y₂May not be present at all, but when at least one is present, they may be the same or different and may be selected from H, Cl^-、Br^-、I^-Cyano, methoxy, acetyl, hydroxy, nitro, trialkylamine, triarylamines (triaryamines), trialkylphosphines, triphenylamine, tosyl, etc.;

a and A' may be the same or different and may be C or N;

m and m' may be the same or different and may be 1 or 2; and

M_efe, Ti, Ru, Co, Ni, Cr, Cu, Mn, Pd, Ag, Rh, Pt, Zr, Hf, Nb, V, Mo, etc.

Of course, depending on the valence state, the element represented by Me may have, in addition to the carbocyclic ligands mentioned above, an additional ligand associated therewith- -Y₁And Y₂- - (e.g. wherein M_eIs Ti, and Y₁And Y₂Is Cl^-)。

Alternatively, the metallocene of structure I may be modified to include materials such as those encompassed by metallocene structure IA:

wherein R is₁、R₂、Y₁、Y₂A, A ', M' and M_eThe definition of (A) is as above. A particularly desirable example of such a material is where R is₁And R₂Each is H; y is₁And Y₂Each is Cl; a and A' are each N; m and M' are each 2, and M_eIs Ru.

Within the metallocenes of structure I, a very suitable metallocene can be selected from the metallocenes of structure II:

wherein R is₁、R₂And M_eAs defined above.

Particularly suitable metallocenes of structure I can be selected, wherein R₁、R₂、Y₁、Y₂M and m' are as defined above and Me is selected from Ti, Cr, Cu, Mn, Ag, Zr, Hf, Nb, V and Mo.

Desirably, the metallocene is selected from the ferrocene class (i.e., where M is_eIs Fe), for example ferrocene, vinylferrocene, ferrocene derivatives, for example butylferrocene or diarylphosphine metal-complexed ferrocene [ e.g. 1, 1-bis (diphenylphosphino) ferrocene-palladium dichloride]Titanocene (i.e., wherein M is_eIs Ti), e.g. bis (. mu.s)⁵-2, 4-cyclopentadien-1-yl) -bis- [2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl]Titanium (which is commercially available from IGM Resins b.v. (the netherlands) under the trade designation "IRGACURE"784 DC), and derivatives and combinations thereof. A particularly desirable metallocene is ferrocene.

And dialkylmetallocenes, such as dialkylferrocenes (e.g., dialkylferrocenyl ethane, propane, butane, etc.) are also suitable for use herein, particularly since about half of the equivalent weight of the material (as compared to the non-dialkylmetallocene) can be used to obtain the results sought, all else being unchanged. Of these materials, bis-ferrocenyl ethane is particularly desirable.

Of course, other materials may be well suited for use as the metallocene component. For example, M_e[CW₃-CO-CH＝C(O^-)-CW'₃]₂Wherein Me is as defined above and W' may be the same or different and may be selected from H and halogen, such as F and Cl. Examples of such materials include platinum (II) acetylacetonate ("ptacc"), cobalt (II) acetylacetonate ("coacc"), nickel (II) acetylacetonate ("niacc"), and copper (II) acetylacetonate ("CuACAC"). Combinations of those materials may also be used.

A variety of photoinitiators can be used herein to provide the benefits and advantages of the invention referenced above. Photoinitiators increase the speed of the curing process when the photocurable composition as a whole is exposed to electromagnetic radiation. Certain metallocenes, such as "IRGACURE"784DC, can serve the dual purpose of both the metallocene and the photoinitiator.

Examples of photoinitiators suitable for use herein include, but are not limited to, those commercially available under the trade designations "IRGACURE" and "DAROCUR" from IGM Resins b.v. (the netherlands), in particular "IRGACURE" 184 (1-hydroxycyclohexyl phenyl ketone), 907 (2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one), 369 (2-benzyl-2-N, N-dimethylamino-1- (4-morpholinophenyl) -1-butanone), 500 (a combination of 1-hydroxycyclohexyl phenyl ketone and benzophenone), 651(2, 2-dimethoxy-2-phenylacetophenone), 1700 (bis (2, 6-dimethoxybenzoyl-2, 4-, 4-trimethylpentyl) phosphine oxide in combination with 2-hydroxy-2-methyl-1-phenyl-propan-1-one) and 819[ bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide ] and "DAROCUR"1173 (2-hydroxy-2-methyl-1-phenyl-1-propane) and 4265(2,4, 6-trimethylbenzoyl diphenylphosphine oxide in combination with 2-hydroxy-2-methyl-1-phenyl-propan-1-one); and visible [ blue ] photoinitiator, dl-camphorquinone, and "IRGACURE"784 DC. Of course, combinations of these materials may also be employed herein.

Other photoinitiators useful herein include alkyl pyruvates, such as methyl, ethyl, propyl, and butyl pyruvates, and aryl pyruvates, such as phenyl, benzyl pyruvates, and appropriately substituted derivatives thereof.

Photoinitiators particularly suitable for use herein include ultraviolet photoinitiators, such as 2, 2-dimethoxy-2-phenylacetophenone (e.g.,"IRGACURE" 651) and 2-hydroxy-2-methyl-1-phenyl-1-propane (e.g., "DAROCUR" 1173), bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide (e.g., "IRGACURE" 819), ultraviolet/visible photoinitiator combinations of 2,4, 6-trimethylbenzoyldiphenylphosphine oxide (e.g., "IRGACURE" TPO), (ethyl 2,4, 6-trimethylbenzoyl) phenylphosphinate (e.g., "IRGACURE" TPO-L), and bis (2, 6-dimethoxybenzoyl-2, 4, 4-trimethylpentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (e.g., "IRGACURE" 1700), and the visible photoinitiator bis (η).⁵-2, 4-cyclopentadien-1-yl) -bis [2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl]Titanium (e.g., "IRGACURE"784 DC).

The plasticizer component should be a short chain alkylene compound having a plurality of alkyl ester and/or reverse alkyl ester substituents thereon. Ideally, the short chain alkylene compound should have 3 or 4 carbon atoms. The short chain alkylene compound should also be a straight chain compound (as opposed to branched or cyclic). The short chain alkylene compound should also have two to four substituents thereon. These substituents should be lower alkyl (e.g., in this case, C)_1-3) Esters or reverse esters. Thus, specific examples of plasticizers are:

the plasticizer component should be used in an amount of about 5% to less than about 35%, for example about 15 to about 30%, desirably about 25%, by weight based on the total composition.

More specifically, the plasticizer component may be comprised of a three carbon structure having methyl esters and/or retro-methyl esters attached thereto.

Accelerators may also be included in the cyanoacrylate compositions of the present invention, for example selected from any one or more of the following: calixarenes and oxacalixarenes, silacrown ethers (silacrowns), crown ethers, cyclodextrins, poly (ethylene glycol) di (meth) acrylates, ethoxylated hydroxyl-containing compounds, and combinations thereof.

Among calixarenes and oxacalixarenes, many are known and reported in the patent literature. See, for example, 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 expressly incorporated herein by reference.

For example, with respect to calixarenes, those in the following structures are useful herein:

wherein R is¹Is alkyl, alkoxy, substituted alkyl or substituted alkoxy; r²Is H or alkyl; and n is 4,6 or 8.

One particularly desirable calixarene is tetrabutyltetra [ 2-ethoxy-2-oxoethoxy ] calix-4-arene.

Many crown ethers are known. For example, examples that may be used herein, alone 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, tripheno-18-crown-6, unsymmetrical-dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8, cyclohexyl-12-crown-4, 1, 2-decyl-15-crown-5, 1, 2-naphtho-15-crown-5, 3,4, 5-naphthyl-16-crown-5, 1, 2-methyl-benzo-18-crown-6, 1, 2-methylbenzo-5, 6-methylbenzo-18-crown-6, 1, 2-tert-butyl-18-crown-6, 1, 2-vinylbenzo-15-crown-5, 1, 2-vinylbenzo-18-crown-6, 1, 2-tert-butyl-cyclohexyl-18-crown-6, asymmetric dibenzo-22-crown-6, and 1, 2-benzo-1, 4-benzo-5-oxo-20-crown-7. See U.S. patent No. 4,837,260(Sato), the disclosure of which is expressly incorporated herein by reference.

Many are also known for silacrown ethers and are reported in the literature.

Specific examples of silacrown compounds useful in the compositions of the present invention include:

see, for example, U.S. patent No. 4,906,317(Liu), the disclosure of which is expressly incorporated herein by reference.

A wide variety of cyclodextrins can be used in the present invention. For example, those described and claimed in U.S. patent No. 5,312,864(Wenz), the disclosure of which is expressly incorporated herein by reference, since hydroxy derivatives of alpha, beta, or gamma-cyclodextrin would be a suitable choice as accelerator components.

For example, poly (ethylene glycol) di (meth) acrylates suitable for use herein include those in the following structures:

where n is greater than 3, for example in the range of 3 to 12, n of 9 is 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 diol moiety in the molecule, excluding two methacrylate groups, expressed in grams/mole (i.e., 400 g/mol). A particularly desirable PEG DMA is PEG 400 DMA.

And for the ethoxylated hydroxyl-containing compound (or ethoxylated fatty alcohol that may be used), the appropriate may be selected from those within the following structures:

wherein C is_mMay be a linear or branched alkyl or alkenyl chain, m is an integer from 1 to 30, for example from 5 to 20, n is an integer from 2 to 30, for example from 5 to 15, and R may be H or an alkyl group, for example C_1-6An alkyl group.

When used, the accelerators included in the above-described structures should be included in the composition in an amount in the range of about 0.01% to about 10% by weight, with a 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.

Stabilizer packages are also commonly found in cyanoacrylate compositions. The stabilizer package may include one or more free radical stabilizers and anionic stabilizers, each of which is known by its name (identity) and amount to one of ordinary skill in the art. See, for example, U.S. patent nos. 5,530,037 and 6,607,632, the disclosures of each of which are incorporated herein by reference.

The radiation source selected to emit electromagnetic waves to photocure the compositions of the present invention can be selected from the group consisting of ultraviolet light, visible light, electron beam, x-ray, infrared radiation, and combinations thereof. Ideally, ultraviolet light is the radiation of choice, and suitable light sources include "H", "D", "V", "X", "M" and "a" lamps, mercury arc lamps and xenon arc lamps; ultraviolet radiation generated by microwaves; solar energy and fluorescent light sources. Any of these electromagnetic radiation sources may be used in conjunction with reflectors and/or filters to focus the emitted radiation onto specific portions of the substrate onto which the photocurable composition has been dispensed and/or within specific regions of the electromagnetic spectrum. Similarly, electromagnetic radiation may be generated directly in a steady manner or in an intermittent manner to minimize the extent of heat accumulation. Although electromagnetic radiation used to cure photocurable compositions into the desired reaction product is generally referred to herein as being in the ultraviolet region, it is not to be understood that other radiation within the electromagnetic spectrum may also be unsuitable. For example, in some cases, radiation in the visible region of the electromagnetic spectrum, either alone or in combination with radiation in the ultraviolet region, for example, may also be advantageously used. Of course, microwaves and infrared radiation may also be advantageously used under appropriate conditions.

Of course, depending on the particular components of the composition selected, higher or lower radiation intensity, more or less exposure thereto and length of exposure, and/or greater or lesser distance of the radiation source from the composition may be required to complete the cure.

More specifically, the selected lamp should have a power rating of at least about 100 watts/inch (about 40 watts/cm), and particularly requires a power rating of at least about 300 watts/inch (about 120 watts/cm), in terms of radiant intensity. In addition, since the inclusion of a photoinitiator in the composition may change the wavelength within the electromagnetic radiation spectrum at which curing occurs, it may be desirable to use an electromagnetic radiation source whose variables (e.g., wavelength, distance, etc.) are easily adjustable.

During curing, the composition will be exposed to a source of electromagnetic radiation, which emits an amount of energy, in KJ/m²Measurement, determined by parameters including: the size, type and geometry of the source; a duration of exposure to electromagnetic radiation; radiation intensity (and the portion of the radiation emitted in the region where curing is suitably effected); the absorption of electromagnetic radiation by any intervening material (e.g., substrate); and the distance of the composition from the radiation source. One skilled in the art will readily appreciate that the cure of the composition can be optimized by selecting appropriate values for these parameters, taking into account the particular components of the composition.

To effect curing, the electromagnetic radiation source may be held stationary while the composition is passed through its path. Alternatively, the substrate coated with the photocurable composition may be held stationary while the electromagnetic radiation source passes over or around it to effect the conversion of the composition into the reaction product. Still alternatively, the two may be moved back and forth with respect to each other, or left still as such, so long as the photocurable composition is exposed to electromagnetic radiation sufficient to effect curing.

Commercially available Curing Systems, such as "ZETA" 7200 or 7400 UV Curing Chamber (Henkel, Rocky Hill, CT), Fusion UV Curing Systems F-300B (Fusion UV Curing Systems, Buffalo Grove, IL), Hanovia UV Curing System (Hanovia Corp., Newark, NJ), Black light Model B-100(Spectroline, Westbury, NY), and RC500APulsed UV Curing System (Xenon Corp., Woburn, MA), are well suited for the purposes described herein.

The desired amount of energy may be delivered by exposing the composition to a weaker-energy electromagnetic radiation source for a longer period of time, by, for example, multiple passes, or by exposing the composition to a stronger-energy electromagnetic radiation source for a shorter period of time. Further, each of those multiple passes may occur at a source of different energy intensity. In any case, the skilled person will select an appropriate source of electromagnetic radiation according to the particular composition and place the source at a suitable distance therefrom, which together with the exposure length optimizes the conversion. Furthermore, it may be desirable to use electromagnetic radiation sources that are delivered in an intermittent manner, such as by pulsing or strobing, to ensure thorough and complete curing without causing excessive heat build-up.

In another aspect of the invention, there is provided a method of bonding two substrates together which comprises applying a composition as described above to at least one substrate and then mating the substrates together to set the adhesive for a sufficient time. For many applications, the substrate should be held by the composition of the present invention in less than about 150 seconds, and depending on the substrate, in as little as about 30 seconds.

In another aspect of the invention, there is provided a cured product of the described composition.

The invention will be further illustrated by the following examples.

Examples

Photocurable compositions were prepared from the ingredients identified in table 1 below in the amounts reported. Each composition also contained 6 wt.% PMMA (as a thickener) and a stabilizer.

TABLE 1

The plasticizers labeled compounds A, B and C are shown below:

the remaining plasticizers (shown below) contain aromatic or cycloaliphatic rings and have a molecular weight greater than 300, except for the plasticizer labeled compound A, B or C. Although dibutyl sebacate is a linear ester, the chain length is 8 carbon atoms (other than 3 or 4 carbon atoms) and the ester is 4 carbon atoms (other than 1,2, or 3 carbon atoms).

MORFLEX 540 (tributyl trimellitate) and MORFLEX 560 (trihexyl trimellitate) are each commercially available from Vartellus Holdings LLC, Indianapolis, IN, and HEXAMOLL DINCH (1, 2-cyclohexane dicarboxylic acid diisononyl ester) is commercially available from BASF corporation, Florham Park, N.J..

For additional comparison purposes, LOCTITE 4310 (commercially available from Henkel, Rocky Hill, CT) is included in Table 2. LOCTITE 4310 contains ethyl cyanoacrylate, metallocene and photoinitiator, and PMMA, consistent with U.S. patent No. 5,922,783.

For example, the elongation at break (in percent) of samples A-G and LOCTITE 4310 after curing by exposure to electromagnetic spectrum radiation. More specifically, seven samples and LOCTITE 4310 were each applied to a transparent mold and exposed to 365nm ultraviolet light generated by a Fusion UV system equipped with a D bulb. The sample is put at 100mW/cm²Cured for a period of 30 seconds per side at an intensity to produce a film thickness in the range of 0.025 to 0.034 inches. In addition to the elongation at break data, the appearance of the cured compositions is also marked in table 3. For each sample, five replicates of the specimen were prepared and evaluated every other sample.

Table 2 below shows the observations for various evaluations.

TABLE 2

As can be seen in table 2, the elongation at break of samples A, B and C is at least 35%. In practice, sample a is 35%, while sample C is 53%, and sample B is 125%. Each of these samples, like the control without plasticizer, cured to a clear reaction product. Other samples showed elongation at break below 35%, actually below 10% (up to 5.6%) and cured as opaque phase separated reaction products.

Additional photocurable cyanoacrylate compositions were prepared from the ingredients identified in table 3 below in the amounts reported. Each composition also contained PMMA as a thickener as well as a stabilizer in an amount of 6 wt%.

TABLE 3

Each of samples H-M was applied between the inwardly facing surfaces of a pair of polycarbonate samples having a length and width of 1 inch and a thickness of 1/4 inches. The assembly thus formed was exposed to 365nm ultraviolet light produced by the LOCTITE Zeta 7411-S UV Flood system at an intensity of 30mW/cm²For 10 seconds.

Table 4 below shows the observations for various evaluations.

TABLE 4

For example, the elongation at break (percent) of samples H-M after curing by exposure to radiation in the electromagnetic spectrum. More specifically, each of the six samples was applied to a transparent mold and exposed to 365nm ultraviolet light generated by a Fusion UV system equipped with a D-bulb. The sample is put at 100mW/cm²Cured per side at an intensity of about 30 seconds, resulting in a film thickness ranging from 0.025 to 0.034 inches. In addition to the elongation at break data, the appearance of the cured compositions, the bulk shear strength of the polycarbonate specimens, and the swing test (swing test) data are also identified in table 4. For each sample, five replicates of the specimen were prepared and evaluated.

As can be seen in table 4, the change in elongation at break depends on whether the plasticizer is triethyl acetyl citrate or CITROFOL II, and whether the selected amount is a higher endpoint (e.g., 25 wt% or 30 wt%) relative to a lower endpoint (e.g., 10 wt%, 15 wt%, or 20 wt%).

For acetyl triethyl citrate, 207% elongation at break was observed at a level of 30 wt%, whereas the value dropped to 28% at 15%. For CITROFOL II, an elongation at break of 101% was observed at a level of 25 wt%.

Bulk shear strength was measured on polycarbonate substrates after mating the substrates with the sample between them and exposing the so mated substrates to UV radiation. Desirably, as shown in Table 4, the reaction products of the samples exhibit an overall shear strength on polycarbonate of greater than about 1800psi, desirably greater than about 1900psi, for example greater than about 2200 psi.

The swing test measurements were made using a digital multifunction controller, cycling through 180 ° rotations starting from the 9 o 'clock position, with one cycle rotating counterclockwise from the 9 o' clock position to the 3 o 'clock position, holding there for 1 second, then rotating clockwise back to the 9 o' clock position and where it is held for 1 second. In this way, the time to perform 60 cycles was measured to be 149 seconds. Each sample subjected to the swing test was applied to the outer circumference of a PVC pipe, inserted with a Y-connector, and then exposed to ultraviolet light emitted from the LOCTITE brand 405LED Flood system to cure the Y-connector to the PVC pipe. A 1kg object was clamped approximately 1 inch from the end of the non-bonded side PVC pipe and allowed to hang freely for cyclic motion. The number of cycles that the PVC tubing completely detached from the Y-connector was marked as the point of failure and recorded.