阅读说明：本技术 两部分氰基丙烯酸酯/可阳离子固化粘合剂体系 (Two-part cyanoacrylate/cationically curable adhesive systems ) 是由 A·穆尼 S·赖利 D·穆尔 于 2020-02-25 设计创作，主要内容包括：本发明提供两部分氰基丙烯酸酯/可阳离子固化粘合剂体系。(The present invention provides a two-part cyanoacrylate/cationically curable adhesive system.)

1. A two-part curable composition comprising:

(a) a first part comprising a cyanoacrylate component, silica having hydrophobic and hydrophilic groups on the surface, and a cationic catalyst; and

(b) a second part comprising a cationically curable component,

wherein the cationic catalyst initiates curing of the cationically curable component when mixed together.

2. The composition of claim 1, wherein the cyanoacrylate component comprises H₂C ═ C (cn) -COOR, where R is selected from alkyl, alkoxyalkyl, cycloalkyl, alkenyl, aralkyl, aryl, allyl, and haloalkyl.

3. The composition of any one of the preceding claims, wherein the cationic catalyst comprises a lithium salt and a salt of a metal of group II of the periodic table of elements and a non-nucleophilic acid.

4. The composition of any one of the preceding claims, wherein the cationic catalyst is a non-nucleophilic acid having a pH of less than 1.0 when measured as a 10 wt.% aqueous solution.

5. The composition of any one of the preceding claims, wherein the cationic catalyst is a member selected from the group consisting of: fluoroboric acid, fluoroarsenic acid, fluoroantimonic acid and fluorophosphoric acid, lithium tetrafluoroborate, calcium bis (tetrafluoroborate), magnesium bis (tetrafluoroborate), lithium hexafluorophosphate, calcium bis (hexafluorophosphate), magnesium bis (hexafluorophosphate), lithium hexafluoroantimonate and lithium hexafluoroarsenate, lanthanide triflates, aryl iodonium salts, aryl sulfonium salts, lanthanum triflate, ytterbium triflate, trimethoxyboroxine-aluminum acetylacetonate, amine-boron trihalide complexes, quaternary ammonium salts, quaternary phosphonium salts, triarylsulfonium salts, diaryl iodonium salts and diazonium salts, trialkoxyboroxine curing agents, and combinations thereof.

6. The composition of any of the preceding claims, wherein the cationically curable component is selected from the group consisting of an epoxy component, an episulfide component, an oxetane component, a vinyl ether component, and combinations thereof.

7. The composition according to any of the preceding claims, wherein the cationically curable component is an epoxy component selected from the group consisting of cycloaliphatic epoxies, aromatic epoxies, aliphatic epoxies, and hydrogenated aromatic epoxies.

8. The composition of claim 6 or 7, wherein the epoxy component comprises a member selected from the group consisting of: epoxy-functionalized hydrogenated bisphenol A, bisphenol F, bisphenol E, bisphenol S, and biphenyl.

9. The composition of any of the preceding claims, wherein the first part is contained in a first chamber of a dual chamber syringe and the second part is contained in a second chamber of the dual chamber syringe.

10. The composition of any one of the preceding claims, wherein the first part further comprises phosphoric acid.

11. The composition of any of the preceding claims, wherein the second part further comprises at least one of a plasticizer, a filler, a thixotropic agent, and a toughening agent.

12. The composition of claim 11, wherein the toughening agent is a member selected from the group consisting of: (1) a reaction product of (a) a combination of ethylene, methyl acrylate, and a monomer having a carboxylic acid cure site, (2) (b) a dimer of ethylene and methyl acrylate, (3) (a) and (b) combination, (4) a vinylidene chloride-acrylonitrile copolymer, (5) and a vinyl chloride/vinyl acetate copolymer, (6) a copolymer of polyethylene and polyvinyl acetate, and combinations thereof.

13. The composition of any one of the preceding claims, wherein the first portion and the second portion are present in a ratio of about 1:1 by volume.

14. The composition of any preceding claim, wherein the first part and the second part are each contained in separate chambers of a dual-chamber container.

15. The composition of any of the preceding claims wherein the hydrophobic groups on the silica surface comprise organosilane groups.

16. A composition according to any preceding claim, wherein the hydrophobic groups on the silica surface comprise alkyltrialkoxysilane groups.

17. A composition according to any preceding claim, wherein the hydrophobic groups on the silica surface comprise alkyltrimethoxy silane groups.

18. The composition of any preceding claim, wherein the hydrophobic groups on the silica surface comprise hexadecyltrimethoxysilane groups.

19. The composition of any preceding claim, wherein the hydrophilic groups on the silica surface comprise silanol groups.

20. A composition comprising a cyanoacrylate component, silica having hydrophobic and hydrophilic groups on the surface, and a cationic catalyst.

21. The composition of claim 20 wherein the silica has a BET surface area of 170-210 and a carbon content of 0.9-1.8%.

22. The composition of claim 20 or claim 21, wherein the silica has been post-treated with hexadecylsilane.

Technical Field

The present invention provides a two-part cyanoacrylate/cationically curable adhesive system.

Brief introduction to the related art

Curable compositions such as cyanoacrylate adhesives are well known for their excellent ability to rapidly bond to a wide range of substrates, typically in minutes, often in seconds, depending on the particular substrate.

Polymerization of cyanoacrylates is initiated by nucleophiles found on most surfaces under atmospheric conditions. Initiation by surface chemistry means that sufficient initiating species are present when the two surfaces are brought into intimate contact with a small layer of cyanoacrylate between the two surfaces. Under these conditions, a firm adhesion was obtained in a short time. Thus, in essence, cyanoacrylates generally act as instant adhesives.

The performance, particularly the durability, of cyanoacrylate adhesives often becomes suspect when exposed to elevated temperature conditions and/or high relative humidity conditions. To address these application-dependent disadvantages, a number of additives have been identified for inclusion in cyanoacrylate adhesive formulations. Improvements would still be considered beneficial.

Cationically curable compositions are generally well known, and one of the main examples of them is the widely used epoxy composition. Epoxy compositions are known to form strong bonds between substrates made of many different types of materials once cured. However, epoxy compositions, whether one-part or two-part, do not have any of the same fast fixture times shown by cyanoacrylates and may tend to exhibit poor performance on substrates constructed of certain materials, particularly plastic substrates such as polycarbonate ("PC"), acrylonitrile-butadiene-styrene ("ABS"), polymethyl methacrylate ("PMMA"), and polyvinyl chloride ("PVC"), to name a few.

Conventional thixotropic additives that are compatible with cyanoacrylates have proven to be incompatible with cationic catalysts used in recently developed two-part cyanoacrylate/cationically curable adhesive systems (such as those sold by Henkel under the trade name LOCTITE, e.g., LOCTITE 4090). (see, for example, U.S. Pat. No.8,742,048)

This incompatibility has hindered the development of thixotropic and non-sagging forms of these breakthrough adhesive systems.

It would be desirable to provide an adhesive system that combines the characteristics of an instant adhesive (such as the fast fixture time observed with cyanoacrylates and the ability to bond to a wide range of substrates such as metals and plastics) with the robust bond strength observed with epoxy compositions and provides thixotropic properties to the adhesive system.

Background

Disclosure of Invention

Herein, silica having hydrophobic groups and hydrophilic groups on the surface has been shown to have excellent compatibility with cationic catalysts present in cyanoacrylate-based part a compositions.

Accordingly, in one aspect, a composition is provided that includes a cyanoacrylate component, silica having hydrophobic and hydrophilic groups on the surface, and a cationic catalyst.

In another aspect, the composition described in the preceding paragraph is used as a first part in a two-part curable composition with a second part comprising a cationically curable component, such as an epoxy component, an episulfide component, an oxetane component, and combinations thereof. When mixed together, the cationic catalyst initiates curing of the cationically curable component. Additionally, the cationically curable component can initiate curing of the cyanoacrylate.

Room temperature curable compositions provide good performance for substrates constructed of a wide variety of materials, such as polycarbonate ("PC"), acrylonitrile butadiene styrene ("ABS"), polymethylmethacrylate ("PMMA"), and polyvinyl chloride ("PVC"), and provide improved durability performance over conventional cyanoacrylate compositions, as well as improved fixture time and improved plastic adhesion over conventional cationically curable compositions.

Detailed Description

Part A

The cyanoacrylate component includes cyanoacrylate monomers, for example H₂C ═ C (cn) -COOR, wherein R is selected from C_1-15Alkyl radical, C_2-15Alkoxyalkyl radical, C_3-15Cycloalkyl radical, C_2-15Alkenyl radical, C_7-15Aralkyl radical, C_6-15Aryl radical, C_3-15Allyl and C_3-15A haloalkyl group. Desirably, the cyanoacrylate monomer is selected from the group consisting of methyl cyanoacrylate, ethyl-2-cyanoacrylate, propyl cyanoacrylate, butyl cyanoacrylate (e.g., n-butyl-2-cyanoacrylate), octyl cyanoacrylate, allyl cyanoacrylate, β -methoxyethyl cyanoacrylate, and combinations thereof. One particularly desirable is ethyl-2-cyanoacrylate ("ECA").

The cyanoacrylate component should be included in the part a composition in an amount of from about 50% to about 99.98% by weight, for example from about 65% to about 85% by weight is preferred, and from about 75% to about 97% by weight of the total part a composition is particularly preferred.

Silica having hydrophobic groups and hydrophilic groups on its surface is neither strictly hydrophobic silica filler nor strictly hydrophilic silica filler. The balance of hydrophobic and hydrophilic groups on the silica surface appears to be important in allowing the part a composition to attain physical properties (e.g., thixotropy) deemed suitable for use in the two-part curable compositions described herein.

The silica having hydrophobic groups and hydrophilic groups on the surface should be included in the part a composition in an amount in the range of from about 0.50 wt% to about 10 wt% based on the weight of the total part a composition, for example, from about 1 wt% to about 7.5 wt% based on the weight of the total part a composition is desirable, and from about 2.5 to about 5 wt% based on the weight of the total part a composition is particularly desirable.

Silicas having hydrophobic and hydrophilic groups on the surface are commercially available, for example under the trade name AEROSIL from Evonik. A particularly desirable commercially available silica having hydrophobic and hydrophilic groups on its surface is AEROSIL^TMAnd R816. The manufacturer Evonik reported the chemical name of a hydrolysate of silica with hexadecyltrimethoxysilane (CAS-No.199876-45-4), which is fumed silica post-treated with hexadecylsilane, particularly hexadecyltrimethoxysilane. Some of the features of such surface-treated fumed silica that are notable in the present inventionIncluding a BET surface area of 170-210 (by the test method in ISO9277) and a carbon content of 0.9-1.8 (by the test method in ISO 3262-20).

As cationic catalyst included in the part a composition of the two-part adhesive system, a hard cationic non-nucleophilic anionic catalyst should be used. Examples of such catalysts include lithium salts and salts of metals of group II of the periodic table, as well as non-nucleophilic acids. The pH of the non-nucleophilic acid is less than 1.0 when measured as a 10 wt% aqueous solution, and the anionic portion of the acid does readily participate in displacement reactions with organic halides. Examples of group II metal salts include calcium and magnesium. Examples of non-nucleophilic acids include fluoroboric acid, fluoroarsenic acid, fluoroantimonic acid, and fluorophosphoric acid. Thus, examples of salts of hard cationic non-nucleophilic anions include: lithium tetrafluoroborate, calcium bis (tetrafluoroborate), magnesium bis (tetrafluoroborate), lithium hexafluorophosphate, calcium bis (hexafluorophosphate), magnesium bis (hexafluorophosphate), lithium hexafluoroantimonate and lithium hexafluoroarsenate. Appropriate combinations may be used.

Cationic catalysts may also include triflates, aryl iodonium salts, aryl sulfonium salts, lanthanum triflate, ytterbium triflate, trimethoxyboroxine-aluminum acetylacetonate, amine-boron trihalide complexes, quaternary ammonium salts, quaternary phosphonium salts, tri-aryl sulfonium salts, diaryl iodonium salts, and diazonium salts of lanthanide elements. Appropriate combinations may be used.

Other cationic catalysts suitable for use in the part a composition of the adhesive system of the present invention are trialkoxyboroxine-based curing agents, such as described in U.S. patent nos. 4,336,367 and 6,617,400, the respective disclosures of which are hereby incorporated by reference. Of course, combinations of any two or more of these cationic catalysts may also be used.

Suitable for use as some or all of the cationic catalysts are boron trifluoride, boron trifluoride-etherate, sulfur trioxide (and their hydrolysis products) and methanesulfonic acid, which are commonly used to stabilize cyanoacrylate monomers against anionic polymerization (see below), which is a known problem of shelf-life stability. Appropriate combinations may be used.

Typically, the amount of cationic catalyst will fall within the range of from about 0.001 wt% to about 10.00 wt% based on the part a composition, preferably from about 0.01 wt% to about 5.00 wt% of the part a composition, for example from about 0.50 wt% to 2.50 wt% of the part a composition.

Additives may be included in the part a composition of the adhesive system to impart physical properties such as improved fixture speed, improved shelf life stability, flexibility, thixotropy, increased viscosity, color, and improved toughness. Thus, such additives may be selected from accelerators, free radical stabilizers, anionic stabilizers, gelling agents, thickeners [ such as PMMAs ], thixotropy-imparting agents (such as fumed silica), dyes, toughening agents, plasticizers, and combinations thereof.

These additives are discussed in more detail below. However, accelerators and stabilizers are discussed herein.

One or more accelerators may also be used in the adhesive system, particularly in the part a composition, to accelerate the cure of the cyanoacrylate component. These accelerators may be selected from the group consisting of calixarenes and oxacalixarenes, silacrown ethers (silacrowns), crown ethers, cyclodextrins, poly (ethylene glycol) di (meth) acrylates, ethoxylated hydroxyl-containing compounds (hydroxyl compounds), and combinations thereof.

Many of calixarenes and oxacalixarenes are known and have been reported in the patent literature. See, for example, U.S. patent 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 of the following structures may be used in the present invention:

wherein R is¹Is C_1-4Alkyl, alkoxy, substituted alkyl or substituted alkoxy; r²Is H or C_1-4An alkyl group; and n is 4,6 or 8.

One particularly preferred 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, asymmetric (asym) -dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8, cyclohexyl-12-crown-4, 1, 2-naphthylalkyl (decalyl) -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-butylcyclohexyl-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 of silacrown ethers are also known and have been reported in the literature. For example, a typical silacrown may be represented within the following structure:

wherein R is³And R⁴Is an organic radical which does not itself cause polymerization of the cyanoacrylate monomer, R⁵Is H or CH₃And n is an integer between 1 and 4. Suitable R³And R⁴Examples of radicals are the R radical, alkoxy radicals such as the methoxy radical and aryloxy radicals such as the phenoxy radical. R³And R⁴The groups may contain halogens or other substituents, for example trifluoropropyl. However, it is not suitable as R⁴And R⁵The radical of the group is a basic group such as amino, substituted amino and alkylamino.

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

dimethylsiloxane-11-crown-4;

dimethylsiloxane-14-crown-5;

and dimethylsiloxane-17-crown-6. See, for example, U.S. patent No. 4,906,317(Liu), the disclosure of which is expressly incorporated herein by reference.

Many cyclodextrins can be used in the present invention. For example, those disclosed and claimed in U.S. patent No. 5,312,864(Wenz), the disclosure of which is described herein specifically by reference, are suitable choices for use as accelerator components herein because the hydroxy derivatives of alpha, beta, or gamma-cyclodextrin are at least partially soluble in cyanoacrylates.

Additionally, poly (ethylene glycol) di (meth) acrylates suitable for use in the present invention include those falling within the following structure:

where n is greater than 3, for example in the range from 3 to 12, n is particularly preferably 9. More specific examples include PEG 200DMA (where n is about 4), PEG 400DMA (where n is about 9), PEG 600DMA (where n is about 14), and PEG 800DMA (where n is about 19), where the number (e.g., 400) represents the average molecular weight of the ethylene glycol moiety in the molecule, excluding two methacrylate groups, expressed as grams/mole (i.e., 400 g/mole). A particularly preferred PEG DMA is PEG 400 DMA.

Suitable in the ethoxylated hydroxyl-containing compound (or ethoxylated fatty alcohol which may be employed) may be selected from those falling within the following structures:

where Cm can be a linear or branched alkyl or alkenyl chain, m is an integer between 1 and 30, such as 5 to 20, n is an integer between 2 and 30, such as 5 to 15, and R can be H or an alkyl group, such as C_1-6An alkyl group.

Commercially available examples of such materials include those provided under the tradename DEHYDOL from BASF of dusseldov, germany, such as DEHYDOL 100.

Further, the accelerator comprises the structure:

wherein R is hydrogen, C_1-6Alkyl radical, C_1-6Alkoxy, alkyl sulfide, haloalkyl, carboxylic acid and their esters, sulfinic acid, sulfonic acid and sulfurous acid and their esters, phosphinic acid, phosphonic acid and phosphorous acid and their esters, Z is a polyether linkage, as defined above, n is 1 to 12 and p is 1 to 3, and R' is the same as R, and g is the same as n.

Particularly preferred chemicals as promoter components in this class are:

wherein the sum of n and m is greater than or equal to 12.

Accelerators should be included in the composition in an amount of from about 0.01% to about 10% by weight of the total part a composition, with a range of from about 0.1% to about 0.5% by weight of the total part a composition being preferred, and about 0.4% by weight of the total part a composition being particularly preferred.

Stabilizers used in the adhesive system part a composition include free radical stabilizers, anionic stabilizers, and stabilizer packages including combinations thereof. The type and amount of such stabilizers are well known to those 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. Common free radical stabilizers include hydroquinone, while common anionic stabilizers include boron trifluoride, boron trifluoride-etherate, sulfur trioxide (and its hydrolysis products), and methanesulfonic acid. As mentioned above, these anionic stabilizers may also be used as cationic catalysts or as part of them. Appropriate combinations may be used.

Part B

Cationically curable monomers used in part B compositions of the adhesive system include epoxy monomers, episulfide monomers, oxetane monomers, and combinations thereof.

The epoxy monomers used in the part B composition include a number of epoxy monomers, some of which are aromatic, some of which are aliphatic, and some of which are cycloaliphatic. Examples of such epoxy monomers include: bisphenol F diglycidyl ether (and hydrogenated versions thereof), bisphenol A diglycidyl ether (and hydrogenated versions thereof), bisphenol S diglycidyl ether (and hydrogenated versions thereof), bisphenol E diglycidyl ether (and hydrogenated versions thereof), biphenyl diglycidyl ether (and hydrogenated versions thereof), 4-vinyl-1-cyclohexene diepoxide, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate, limonene diepoxide, hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, aniline diglycidyl ether, propylene glycol diglycidyl ether, cyanuric acid triglycidyl ether, phthalic acid diglycidyl ether, diglycidyl ester of linoleic acid dimer acid, dicyclopentadiene diepoxide, tetrachlorobisphenol a glycidyl ether, 1,1, 1-tris (p-hydroxyphenyl) ethane glycidyl ether, tetraglycidyl ether of tetrakis (4-hydroxyphenyl) ethane, epoxy phenol novolac resin, epoxy cresol novolac resin, tetraglycidyl-4, 4' -diaminodiphenylmethane, and the like. Appropriate combinations may be used.

Commercially available epoxy resins suitable for use are polyglycidyl derivatives of phenolic compounds, such as those available under the trade names EPON 828, EPON 1001, EPON 1009 and EPON 1031 from Shell Chemical co, DER 331, DER332, DER334 and DER 542 from Dow Chemical co; GY285 available from Vantico, Tarrytown, NY; and BREN-S from Nippon Kayaku, Japan; epoxidized polybutadienes such as those commercially available under the trade designation PolyBD from Sartomer, EPOLEAD PB 3600 from Daicel; JP-100 and JP-200 from Nippon Soda, epoxidized liquid isoprene rubbers such as KL-610, KL-613 and KL-630T from Kuraray; and epoxidized liquid polyisoprenes such as EPOXYPRENE 25 and EPOXYPRENE 50 from Sanyo corporation. Other suitable epoxy resins include polyepoxides and the like prepared from polyols and polyglycidyl derivatives of phenol-formaldehyde novolacs which are commercially available under the trade names DEN 431, DEN 438, DEN 439 from Dow Chemical Company. Analogs of cresol may also be commercially available ECN1235, ECN 1273 and ECN 1299 from Ciba Specialty Chemicals. SU-8 is a bisphenol A type epoxy novolac resin available from Resolution. Of course, cycloaliphatic epoxy resins, such as those available under the tradename CYRACURE, and hydrogenated bisphenol and biphenyl type epoxy resins, such as those available under the tradename EPALLOY, are suitable for use herein. Appropriate combinations may be used.

Cycloaliphatic epoxy resins contain at least one cycloaliphatic group and at least one ethylene oxide group, typically two ethylene oxide groups. Representative cycloaliphatic epoxy resins include 2- (3, 4-epoxy) cyclohexyl-5, 5-spiro- (3, 4-epoxy) cyclohexane-m-dioxane, 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, 3, 4-epoxy-6-methylcyclohexylmethyl-3, 4-epoxy-6-methylcyclohexanecarboxylate, vinylcyclohexane dioxide, bis (3, 4-epoxycyclohexylmethyl) adipate, bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate, exo-exo bis (2, 3-epoxycyclopentyl) ether, endo-exo bis (2, 3-epoxycyclopentyl) ether, 2, 2-bis (4- (2, 3-glycidoxy) cyclohexyl) propane, 2, 6-bis (2, 3-glycidoxycyclohexyl-p-dioxane), 2, 6-bis (2, 3-glycidoxy) norbornene, the diglycidyl ether of linoleic acid dimer, limonene dioxide, 3-vinylcyclohexene oxide, 3-vinylcyclohexene dioxide, epoxidized poly (1, 3-butadiene-acrylonitrile), epoxidized soybean oil, epoxidized castor oil, epoxidized linseed oil, 2, 2-bis (3, 4-epoxycyclohexyl) propane, dicyclopentadiene dioxide, tricyclopentadiene dioxide, tetracyclopentadiene dioxide, 1, 2-epoxy-6- (2, 3-epoxypropoxy) hexahydro-4, 7-methyleneindane (methanoindane), p- (2, 3-epoxy) cyclopentylphenyl-2, 3-epoxypropyl ether, 1- (2, 3-epoxypropoxy) phenyl-5, 6-epoxyhexahydro-4, 7-methyleneindane, o- (2, 3-epoxy) cyclopentylphenyl-2, 3-epoxypropyl ether, 1, 2-bis [5- (1, 2-epoxy) -4, 7-hexahydromethyleneindanoxy (methanoindanyloxy) ] ethane, cyclopentenylphenyl glycidyl ether, cyclohexanediol diglycidyl ether, and diglycidyl hexahydrophthalate. Siloxane-functionalized epoxy resins may also be used, such as 1, 3-bis (3, 4-epoxycyclohexyl-2-ethyl) -1,1,3, 3-tetramethyldisiloxane and other epoxy-functional linear/cyclic siloxanes, such as those disclosed in U.S. Pat. No. 7,777,064, the disclosure of which is expressly incorporated herein by reference. In a particular embodiment, the cycloaliphatic epoxy resins are 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate and 3, 4-epoxy-6-methylcyclohexylmethyl-3, 4-epoxy-6-methylcyclohexane carboxylate. Other examples of cycloaliphatic epoxides suitable for use include those described in U.S. Pat. No. 6,429,281(Dershem), the disclosure of which is expressly incorporated herein by reference.

Of course, combinations of the above epoxy resins are also preferred for use in the present invention.

The episulfide monomer can be simply all or part of the sulfur-containing 3-membered ring type of the above-described base epoxy monomer.

The oxetane monomer may be selected from:

3-allyloxymethyl-3-ethyloxetane (AOX)

3-Ethyl-3 [ (phenoxy) methyl ] oxetane (POX)

Bis (1-ethyl-3-oxetanyl-methyl) ether (DOX)

F

Oxetanes, labeled a-C, are available from Toa Gosei co. Appropriate combinations may be used.

The vinyl ether monomer may be selected from a number of Materials, such as those commercially available under the trade name VEctomer, available from Vertellus Performance Materials inc. Examples include VEctomer vinyl ether 4010[ bis- (4-vinyloxybutyl) isophthalate ], VEctomer vinyl ether 4060[ bis (4-vinyloxybutyl) adipate ], and VEctomer vinyl ether 5015[ tris (4-vinyloxybutyl) trimellitate ].

The epoxide, episulfide, oxetane and/or vinyl ether monomers can be functionalized with one or more alkoxysilane groups. Examples of such materials include those commercially available from Gelest inc., Morrisville, PA..

As discussed above, additives may be included in either or both of the part a or part B compositions to affect various properties.

Fillers contemplated for optional use include, for example, aluminum nitride, boron nitride, silicon carbide, diamond, graphite, beryllium oxide, magnesium oxide, silica other than silica having hydrophobic and hydrophilic groups on the surface, such as fumed silica, or fused silica, alumina, perfluorinated hydrocarbon polymers (i.e., TEFLON), thermoplastic polymers, thermoplastic elastomers, mica, glass powder, and the like. Preferably, these fillers have a particle size of about 20 microns or less.

With respect to those other silicas, the silica may have a nanoparticle-sized average particle diameter; that is, the average particle size is on the order of 10^-9And (4) rice. The silica nanoparticles may be pre-dispersed in an epoxy resin and may be selected from those sold under the trade name NANOPOX from Nanoresins, germany. NANOPOX is a trade name for a silica nanoparticle reinforced epoxy resin product family, showing an excellent combination of material properties. The silica phase is composed of surface-modified synthetic SiO having a diameter of less than 50nm and an extremely narrow particle size distribution₂And (4) forming nanospheres. SiO 2₂Nanospheres are non-agglomerated dispersions in an epoxy resin matrix, resulting in low viscosity for resins containing no more than 50% by weight silica.

A commercially available example of a particularly preferred NANOPOX product for use herein includes NANOPOX a610 (40 wt% dispersion in a cycloaliphatic epoxy resin matrix). The NANOPOX product is believed to have a particle size of about 5nm to about 80nm, although the manufacturer reports less than 50 nm.

The silica component should be present in an amount of from about 1 to about 60 weight percent, for example from about 3 to about 30 weight percent, desirably from about 5 to about 20 weight percent, based on the total weight of the composition.

Flexibilizing agents (also referred to as plasticizers) contemplated for use include those which reduce the T of the composition_gBranched polyalkanes or polysiloxanes. Such flexibilizing agents include, for example, polyethers, polyesters, polythiols, polysulfides, and the like. If used, the flexibilizing agent is typically present in an amount of from about 0.5% to about 30% by weight of the total part B composition.

The flexibilizing agent may also be reactive; that is, they may be functionalized to react into a cured reaction product. In this case, hydroxyl-functionalized resins may be used, since they tend to co-react with cationically curable components, such as epoxy resins, and thus may alter the mechanical properties of the cured product.

For example, hydroxyl-functionalized aliphatic polyester diols provide improved flexibility to the cured composition. One commercially available example of a diol is available under the trade name K-FLEX A307 from King Industries. K-FLEX A307 is a low viscosity, 100% solids linear, saturated aliphatic polyester diol having primary hydroxyl groups as reported by the manufacturer. K-FLEX a307 was generalized to have been designed as a flexibility modifier for acrylic/isocyanate and acrylic/melamine systems. Commercial applications are advertised as automotive OEM, automotive refinish, aerospace, industrial maintenance, and plastic coatings.

Others include PolyTHF 650/1400/2000/2900 (sold under the trade name TERATHANE), polycaprolactone diols and triols (Aldrich), polydimethylsiloxane-polycaprolactone diols (e.g. WAX 350OH D from Wacker), K-PURE CDR-3441, CDR-3319(King Industry) and primary or secondary hydroxyl terminated polybutadiene/hydrogenated polybutadiene (Cray Valley, e.g. PolyBd/Krasol material).

Toughening agents contemplated for use in particular in the part a compositions include elastomeric polymers selected from elastomeric copolymers of lower olefin monomers with (i) acrylates, (ii) methacrylates, or (iii) vinyl acetate, such as acrylic rubbers; polyester polyurethane; ethylene-vinyl acetate; fluorinated rubber; isoprene-acrylonitrile polymers; chlorosulfonated polyethylene; and homopolymers of polyvinyl acetate are considered particularly useful. [See alsoU.S. Pat. No. 4,440,910(O' Connor), the disclosure of each of which is expressly incorporated herein by reference.]Elastomeric polymers are described in the' 910 patent as either homopolymers of alkyl esters of acrylic acid; copolymers of other polymerizable monomers such as lower olefins with alkyl or alkoxy esters of acrylic acid; and alkyl or alkoxy esters of acrylic acid. Other unsaturated monomers copolymerizable with the alkyl and alkoxy acrylates include dienes, reactive halogen-containing unsaturated compounds, and other acrylic monomers, such as acrylamide. Appropriate combinations may be used.

One such class of elastomeric polymers is, for example, copolymers of methyl acrylate and ethylene, manufactured by DuPont under the designation VAMAC, such as VAMAC N123 and VAMAC B-124. DuPont reports that VAMAC N123 and VAMAC B-124 are masterbatches of ethylene/acrylic elastomers. The dupont material VAMAC G is a similar copolymer, but does not contain fillers to provide color or stabilizers. VAMAC VCS rubber appears to be the base rubber through which other members of the VAMAC product line are compounded. VAMAC VCS (also known as VAMAC MR) is a reaction product of a combination of ethylene, methyl acrylate, and a monomer having a carboxylic acid cure site, which once formed, is then substantially free of processing aids such as the release agents octadecylamine, complex organophosphates and/or stearic acid, and antioxidants such as substituted diphenylamines. Appropriate combinations may be used.

More recently, DuPont has been offered to the market under the tradenames VAMAC VMX 1012 and VCD 6200, which are rubbers made from ethylene and methyl acrylate. It is believed that VAMAC VMX 1012 rubber has little to no carboxylic acid in the polymer backbone. Like the VAMAC VCS rubber, the VAMAC VMX 1012 and VCD 6200 rubbers are substantially free of processing aids such as the release agents octadecyl amine, complex organic phosphate esters, and/or stearic acid mentioned above, and antioxidants such as substituted diphenylamines. All of these VAMAC elastomeric polymers can be used in the present invention.

Further, the composition of part A may contain a vinylidene chloride-acrylonitrile copolymer [2 ]See alsoU.S. Pat. No. 4,102,945(Gleave)]And a vinyl chloride/vinyl acetate copolymer [ sic ], [ solution of (A) and (B) ]See alsoU.S. Pat. No. 4,444,933(Columbus)]. The disclosure of each of these U.S. patents is, of course, incorporated herein by reference in its entirety.

Copolymers of polyethylene and polyvinyl acetate commercially available from LANXESS Limited under the trade name LEVAMELT may be used.

A range of LEVAMELT agents are available and include, for example, LEVAMELT 400, LEVAMELT 600 and LEVAMELT 900. The LEVAMELT products vary in vinyl acetate content. For example, LEVAMELT 400 comprises an ethylene-vinyl acetate copolymer comprising 40 wt% vinyl acetate. LEVAMELT brand products are provided in granular form. The granules were almost colourless and dusted with silica and talc. The LEVAMELT brand of products consists of methylene units forming a saturated main chain with side chain acetate groups. The presence of a fully saturated backbone indicates LEVAMELT is a particularly stable polymer. It does not contain any reactive double bonds that make conventional rubbers prone to ageing reactions, ozone and ultraviolet light. It is reported that a saturated backbone makes it strong.

Interestingly, depending on the polyethylene/polyvinyl acetate ratio, the solubility of these LEVAMELT elastomers varies among different monomers, also due to the solubility the toughening ability varies.

The LEVAMELT elastomer is provided in particulate form and is easier to formulate than other known elastomeric tougheners.

The VINNOL brand surface coating resins marketed by Wacker Chemie AG, munich, germany, represent a wide range of vinyl chloride derived copolymers and terpolymers, which are being generalized for different industrial applications. The main components of these polymers are different compositions of vinyl chloride and vinyl acetate. The terpolymers of the VINNOL product line also contain carboxyl or hydroxyl groups. These vinyl chloride/vinyl acetate copolymers and terpolymers may also be used.

VINNOL surface coating resins with carboxyl groups are terpolymers of vinyl chloride, vinyl acetate and dicarboxylic acids, varying in their molar composition and degree of polymerization and polymerization process. These terpolymers are reported to exhibit excellent adhesion, particularly on metal substrates.

VINNOL surface coating resins with hydroxyl groups are copolymers and terpolymers of vinyl chloride, hydroxyacrylate and dicarboxylate, varying in their composition and degree of polymerization.

VINNOL surface coating resins without functional groups are copolymers of vinyl chloride and vinyl acetate of variable molar composition and degree of polymerization.

Rubber particles, in particular having a relatively small average particle size (For exampleLess than about 500nm, or less than about 200nm) rubber particles may also be included, particularly in the part B composition. Rubber (lip)The gum particles may or may not have a shell of the commonly known core-shell structure.

In the case of rubber particles having a core-shell structure, such particles generally have a core consisting of a polymeric material having elastomeric or rubbery properties, (ii) ((iii))Namely, it isA glass transition temperature of less than about 0 ℃,for exampleLess than about-30 ℃ C.), from a non-elastic polymeric material (Namely, it isThermoplastic or thermosetting/crosslinked polymers having a glass transition temperature above ambient temperature,for exampleGreater than about 50 deg.C) of a shell.For exampleThe core may be composed of a homopolymer or copolymer of a diene (e.g., a homopolymer of butadiene or isoprene, a copolymer of butadiene or isoprene with one or more ethylenically unsaturated monomers such as vinyl aromatic monomers, (meth) acrylonitrile, (meth) acrylate esters, and the like), while the shell may be composed of a polymer or copolymer of one or more monomers such as (meth) acrylate esters (meth)For exampleMethyl methacrylate), a vinyl aromatic monomer(s) ((II)Such asStyrene), vinyl cyanide(s) (For exampleAcrylonitrile), unsaturated acids and anhydridesFor exampleAcrylic acid), (meth) acrylamide, etc., which have a suitably high glass transition temperature. Other rubbery polymers may also be suitable for the core, including polybutyl acrylate or silicone elastomers: (For examplePolydimethylsiloxanes, in particular crosslinked polydimethylsiloxanes).

The rubber particles may consist of more than two layers (For exampleA central core of one rubber material may be surrounded by a second core of a different rubber material or the rubber core may be surrounded by a double shell of a different composition, or the rubber particles may have the structure: soft core, hard shell, soft shell, hard shell). In one embodiment of the invention, the rubber particles used are composed of a core and at least two concentric shells having different chemical compositions and/or properties. Each of the core or shell or both the core and shell may be crosslinked ((ii))For exampleIonic or covalent). The shell may be grafted to the core. The shell-containing polymer may carry one or more different groups capable of interacting with other components of the composition of the inventionFunctional group of type (A), (B)For exampleEpoxy groups).

Typically, the core will comprise from about 50% to about 95% by weight of the rubber particle, while the shell will comprise from about 5% to about 50% by weight of the rubber particle.

Preferably, the rubber particles are relatively small in size. For example, the average particle size may be from about 0.03 microns to about 2 microns or from about 0.05 microns to about 1 micron. The average diameter of the rubber particles may be less than about 500nm, for example less than about 200 nm. For example, the core-shell rubber particles may have an average diameter in the range of about 25nm to about 200 nm.

Methods of preparing rubber particles having a core-shell structure are known in the art and are described, for example, in U.S. Pat. nos. 4,419,496, 4,778,851, 5,981,659, 6,111,015, 6,147,142, and 6,180,693, each of which is hereby incorporated by reference in its entirety.

The rubber particles having a core-shell structure may be prepared in a master batch (masterbatch) in which the rubber particles are dispersed in one or more epoxy resins, such as diglycidyl ether of bisphenol a. For example, rubber particles are typically prepared in aqueous dispersions or emulsions. Such dispersions or emulsions may be combined with the desired epoxy resin or mixture of epoxy resins and water and other volatile materials removed by distillation or the like. One method of preparing such a masterbatch is described in detail in international patent publication No. WO 2004/108825, the disclosure of which is expressly incorporated herein in its entirety by reference. For example, an aqueous latex of rubber particles may be introduced in contact with an organic medium having partial solubility in water and then in contact with another organic medium having lower partial solubility in water than the first organic medium to separate the water and provide a dispersion of rubber particles in a second organic medium. The dispersion can then be mixed with the desired epoxy resin and volatile materials removed by distillation or the like to provide a masterbatch.

Particularly suitable dispersions of rubber particles having a core-shell structure in an epoxy resin matrix are available from Kaneka Corporation.

For example, the core may be formed primarily from raw materials of polybutadiene, polyacrylate, polybutadiene/acrylonitrile mixtures, polyols and/or polysiloxanes or any other monomers, which provide a low glass transition temperature. The shell may be formed primarily from a material of polymethylmethacrylate, polystyrene, polyvinyl chloride, or any other monomer, which imparts a higher glass transition temperature.

The core shell rubber may have a particle size in the range of 0.07 to 10 microns, for example 0.1 to 5 microns.

The core shell rubber, made in this manner, may be dispersed in a thermosetting resin matrix, such as an epoxy matrix or a phenolic matrix. Examples of epoxy matrices include diglycidyl ethers of bisphenol A, F or S or bisphenols, novolac epoxy resins, and cycloaliphatic epoxides. Examples of the phenolic resin include bisphenol a-based phenoxide. The matrix material is typically a liquid at room temperature.

The dispersion of core shell rubber may be present in an amount in the range of about 5% to about 50% by weight, preferably about 15% to about 25% by weight, based on viscosity considerations. These amounts are based on the total part B composition.

When used, these core shell rubbers allow toughening to occur in the composition and often in a predictable manner-in terms of temperature neutrality to cure-because it is a substantially uniform dispersion that is commonly observed in core shell rubbers, as they are offered for commercial sale.

Many core-shell rubber structures are available from Kaneka, such as those available under the trade name kanace, and are believed to have a core made of a copolymer of (meth) acrylate-butadiene-styrene, with butadiene being the major component in the phase separated particles dispersed in the epoxy resin. Other commercially available masterbatches of core-shell rubber particles dispersed in epoxy resins include GENIOPERL M23A (a dispersion of 30 wt.% core-shell particles in an aromatic epoxy resin based on bisphenol A diglycidyl ether; the core-shell particles have an average diameter of about 100nm and contain a crosslinked silicone elastomer core to which an epoxy-functional acrylate copolymer has been grafted); the silicone elastomer core comprises about 65% by weight of core-shell particles, available from Wacker Chemie GmbH.

In the case of those rubber particles which do not have the shell, the rubber particles can be based on a core of such a structure.

Preferably, the rubber particles are relatively small in size. For example, the average particle size may be about 0.03 microns to about 2 microns, or about 0.05 microns to about 1 micron. In certain embodiments of the invention, the rubber particles have an average diameter of less than about 500 nm. In other embodiments, the average particle size is less than about 200 nm. For example, the rubber particles may have an average diameter in the range of about 25nm to about 200nm, or about 50nm to about 150 nm.

The rubber particles are generally formed from a rubber having the properties of an elastomer or rubber (i.e., a glass transition temperature of less than about 0 c,example (b) Such asLess than about-30 deg.C) of a polymeric material.For exampleThe rubber particles may be composed of homopolymers or copolymers of dienes (e.g., homopolymers of butadiene or isoprene, copolymers of butadiene or isoprene with one or more ethylenically unsaturated monomers such as vinyl aromatic monomers, (meth) acrylonitrile, (meth) acrylates, and the like) and polysiloxanes. The rubber particles may contain functional groups such as carboxylate groups, hydroxyl groups, and the like, and may have a linear, branched, crosslinked, random copolymer, or block copolymer structure.

For example, the rubber particles may be formed primarily from starting materials of dienes such as butadiene, (meth) acrylates, ethylenically unsaturated nitriles such as acrylonitrile, and/or any other monomers which, when polymerized or copolymerized, result in polymers or copolymers having low glass transition temperatures

The rubber particles may be used in dry form or may be dispersed in a matrix, as described above.

Generally, the composition may contain from about 5 to about 35 weight percent rubber particles.

Combinations of different rubber particles may be advantageously used in the present invention. The rubber particles may vary, for example, in terms of particle size, glass transition temperature of the respective material, whether, to what extent, by what material they are functionalized, and whether and how their surface is treated.

One part of the rubber particles may be provided in the form of a masterbatch, in which the particles are stably dispersed in an epoxy resin matrix, while another part may be provided in the form of a dry powder to the adhesive composition (Namely, it isWithout any epoxy or other matrix material). For example, the adhesive composition can be prepared by simultaneously using a first type of rubber particles having an average particle diameter of about 0.1 μm to about 0.5 μm in a dry powder form, and a second type of rubber particles having an average particle diameter of about 25nm to about 200nm stably dispersed in a liquid bisphenol A diglycidyl ether matrix at a concentration of about 5 weight percent to about 50 weight percent. For example, the first type: the weight ratio of the second type of rubber particles may be about 1.5:1 to about 0.3: 1.

The chemical composition of the rubber particles may be substantially uniform throughout each particle. However, the outer surface of the particles is modified by reaction with a coupling agent, an oxidizing agent, or the like to improve the dispersibility of the rubber particles in the adhesive composition (For exampleTo reduce agglomeration of the rubber particles and to reduce the tendency of the rubber particles to settle out of the adhesive composition). The modification of the surface of the rubber particles may also enhance the adhesion of the epoxy matrix to the rubber particles upon curing of the adhesive. The rubber particles may optionally be irradiated to alter the degree of cross-linking of the polymers making up the rubber particles in different regions of the particles. For example, the rubber particles may be treated with gamma radiation such that the rubber is more cross-linked near the surface of the particles than in the center of the particles.

Rubber particles suitable for use in the present invention are available from commercial sources. For example, rubber particles such as NEP R0401 and NEP R401S (both based on acrylonitrile/butadiene copolymers) available from Eliokem, inc; NEP R0501 (based on carboxylated acrylonitrile/butadiene copolymers; CAS No.: 9010-81-5); NEP R0601A (based on hydroxy-terminated polydimethylsiloxane; CAS number 70131-67-8); and NEP R0701 and NEP 0701S (butadiene/styrene/2-vinylpyridine-based copolymer, CAS number 25053-48-9). Further, those are available under the PARALOID trade names, such as PARALOID 2314, PARALOID 2300 and PARALOID 2600, from Dow Chemical Co, philadelphia, PA, and those under the STAPHYLOID trade name, such as STAPHYLOID AC-3832, from Ganz Chemical Co.

Rubber particles that have been treated with reactive gases or other agents to modify the exterior surface of the particles by, for example, creating polar groups (e.g., hydroxyl groups, carboxylic acid groups) on the surface of the particles are also suitable for use in the present invention. Examples of reactive gases include, for example, ozone, Cl₂、F₂、O₂、SO₃And an oxidizing gas. Methods of modifying the surface of rubber particles using such agents are known in the art and are described, for example, in U.S. patent nos. 5,382,635; 5,506,283, respectively; 5,693,714, respectively; and 5,969,053, each of which is incorporated herein by reference in its entirety. Suitable surface modified rubber particles are also available from commercial sources, such as the rubber sold under the trade name VISTAMER by exosia.

When the rubber particles are initially provided in dry form, it is advantageous to ensure that such particles are well dispersed in the adhesive composition before the adhesive composition cures. That is, agglomerates of the rubber particles are preferably broken up to provide discrete individual rubber particles, which can be achieved by intimately and intimately mixing the dry rubber particles with the other components of the adhesive composition. For example, the dried rubber particles may be mixed with the epoxy resin and ground or melt mixed for a period of time effective to substantially completely disperse the rubber particles and to break up any agglomeration of the rubber particles.

Furthermore, Nanoresins are available under the trade name ALBIDUR (epoxy resins containing core-shell silicone rubber particles; e.g., EP2240A, EP 5340); ALBIFLEX (epoxy-siloxane block copolymer resin); and ALBIPOX (an epoxy resin containing an adduct of epoxy-nitrile butadiene rubber). Appropriate combinations may be used.

Thickeners may also be used.

Other additives may also be included in the part a composition. For example, phosphoric acid may be included in the part a composition. Improved strength and strength retention can be observed when included at a level of about 50ppm to about 1,000ppm, for example about 100ppm to about 500ppm, and applied to at least one aluminum substrate to be incorporated in an adhesive assembly. More specifically, humidity, heat aging and solvent soak tests show that the addition of phosphoric acid to the two-part cyanoacrylate/cationically curable adhesive systems of the present invention makes it possible to achieve significantly improved adhesives having excellent properties for both metals and plastics, especially durability to aluminum.

In practice, the part a and part B compositions are each contained in a separate container in the apparatus prior to use, and the two parts are removed from the container and mixed and applied to the substrate surface at the time of use. The container may be a dual chamber cartridge in which separate portions are advanced through a bore (which may be a common one or adjacent ones) through a chamber with a piston, and then through a mixing and dispensing nozzle. Or the containers may be coaxial or side-by-side bags that can be cut or torn apart and the contents mixed and applied to the substrate surface.

The invention will be more readily understood through the following discussion of the examples.

Examples

Unless otherwise indicated, references to CA or cyanoacrylate in the examples refer to ethyl-2-cyanoacrylate.

Referring to table 1, stock solution 1 was prepared as a base part a composition in the amounts recorded from the listed components as follows:

TABLE 1

Components	Amount (wt%)
		Ethyl cyanoacrylate	99.7315
MSA！	0.0085
		Hydroquinone	0.04
MMBP@	0.22

^！Methanesulfonic acid

^@2,2' -methylenebis (6-tert-butyl-4-methylphenol)

Cationic catalyst (LiBF) was added to stock solution 1 in the amounts reported in table 2₄) And fumed silica (CAB-O-SIL TS 720) as a silica component to prepare samples A-E.

TABLE 2

After samples a-E were each placed in a 20 gram bottle and aged at a temperature of 82 ℃ for 3 days, samples a-E were subjected to accelerated aging.

The appearance and viscosity of each sample was recorded before and after aging and is reported in table 3. Stock solution 1 was used for comparison purposes.

TABLE 3

^*The viscosity ratio was determined by using a Physica MCR-100 at 25 ℃ with a CP-50 cone at a shear rate of 3000s^-1And adjusting the viscosity measurement after dividing the initial viscosity.

A viscosity ratio of less than 3 is acceptable.

Referring to table 4, stock solution 2 was prepared as a base part a composition from the listed components in the amounts reported in table 4 below, wherein LiBF₄Added as a cationic catalyst.

TABLE 4

Components	Amount (wt%)
		Ethyl cyanoacrylate	98.7515
MSA	0.0085
		Hydroquinone	0.04
MMBP	0.22
		LiBF4	0.98

Various silica fillers were added to stock solution 2 to determine compatibility with the cationic catalyst in the cyanoacrylate. Table 5 shows the composition of samples F-I.

TABLE 5

After samples F-I were each placed in a 20 gram bottle and aged at a temperature of 82 ℃ for 3 days, samples F-I were subjected to accelerated aging.

The appearance and viscosity of each sample was recorded before and after aging and is reported in table 6. Stock solution 2 was used for comparison purposes.

TABLE 6

Of the four fumed silicas evaluated herein, when combined with LiBF in ethyl cyanoacrylate₄When used in combination, CAB-O-SIL TS 530 was the only silica that did not cause gelation after being left at a temperature of 82 ℃ for 3 days.

However, CAB-O-SIL TS 530 did not produce a high thixotropic effect (as seen from the viscosity ratio). Thus, a considerable amount-between about 5% and up to about 15% by weight-is used to obtain a gel.

Formulations are now prepared at 6% by weight using LOCTITE 454 as the base, AEROSIL R816, CAB-O-SIL TS 720 and AEROSIL R805 as the silica components, respectively, with or without cationic catalysts. Wherein only the combination of AEROSIL R816, cationic catalyst, and ethyl cyanoacrylate gave a gel formulation with anti-sag properties.

Indeed, the combination of AEROSIL R816, a cationic catalyst, and a cyanoacrylate produced part A compositions with excellent stability and thixotropy.

Using LOCTITE 4090 as part a of the base, a formulation with AEROSIL R816 was prepared and evaluated together with a formulation prepared from AEROSIL R805 for comparison purposes. AEROSIL R816 reported by the manufacturer Evonik has a BET surface area of 170-210 (based on ISO9277) and a carbon content of 0.9-1.8 (based on ISO 3262-20). It is fumed silica post-treated with hexadecylsilane. The manufacturer Evonik reports an AEROSIL R805 with a BET surface area of 125-175 (based on ISO9277) and a carbon content of 4.5-6.5 (based on ISO 3262-20). It is fumed silica post-treated with an organosiloxane.

Formulations with AEROSIL R816 showed excellent compatibility with cationic catalysts after accelerated aging.

The formulations were then evaluated for 1:1 mixing ratio relative to part B composition4090 and was found to produce adhesives having similar properties.

International patent publication No. WO 85/01055 states that aerrosil R805 can be added to cyanoacrylates to give non-flowable gels.

Therefore, AEROSIL is used^TMR805 a sample was prepared to which additional ingredients, including a cationic catalyst, were added. Table 7 shows the composition of sample J as follows.

TABLE 7

Components	Sample J/amount (wt%)
		Ethyl cyanoacrylate	74.813
MSA	0.0085
		Hydroquinone	0.04
BHA#	0.09
		Phosphoric acid	0.054
LiBF4	0.98
		VINNOL	8
AEROSIL R 805	6
		SO2	0.045

^#Butylated hydroxyanisole

Sample J was used as part a composition and placed into 50 grams of 1:1 dual cartridges and aged at a temperature of 82 ℃ for periods of 1,2, and 3 days. (part B composition was not placed in another chamber of the cartridge.)

Viscosity measurements were made using a Physica MCR-100(25 ℃, CP-50 cone) as described above and are reported in table 8.

TABLE 8

Sample J showed good sag resistance and improved stability and compatibility compared to samples made with AEROSIL 200 and AEROSIL R973, which gelled after aging for 3 days at a temperature of 82 ℃.

Samples were prepared using a cationic catalyst with AEROSIL R805 or AEROSIL R816. Table 9 shows the composition of samples K and L as follows:

TABLE 9

Each sample was placed in a3 gram aluminum tube and aged at a temperature of 82 ℃ for a period of 3 days.

The viscosity measurements were made during the initial and after aging using the Physica MCR-100 described above (25 ℃, CP-50 cone). Tables 10 and 11 record the various appearance and viscosity measurements observed.

Watch 10

TABLE 11

For comparison, LOCTITE 454 (part A only) was used and aged at a temperature of 35 ℃ in 3 g aluminum tubes. The results are shown in Table 12 below:

TABLE 12

Accelerated aging of sample L as part A composition was conducted in a3 gram aluminum tube at a temperature of 35 ℃.

The viscosity measurements were made using the Physica MCR-100 described above (25 ℃, CP-50 cone). The results are reported in table 13 below.

Watch 13

These results indicate that sample L (a formulation containing ethyl cyanoacrylate, a cationic catalyst and AEROSIL R816) has acceptable stability, the viscosity ratio in accelerated aging studies being consistent with that measured for LOCTITE 454.