CA1297621C - Radiation-cured adhesive system containing amides - Google Patents
Radiation-cured adhesive system containing amidesInfo
- Publication number
- CA1297621C CA1297621C CA000557766A CA557766A CA1297621C CA 1297621 C CA1297621 C CA 1297621C CA 000557766 A CA000557766 A CA 000557766A CA 557766 A CA557766 A CA 557766A CA 1297621 C CA1297621 C CA 1297621C
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- Prior art keywords
- composition
- percent
- acrylamide
- weight
- acrylate
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
Abstract
ABSTRACT OF THE DISCLOSURE
A reactive acrylic adhesive, activated by actinic radiation, includes at least about 0.1 percent by weight of a beta-unsaturated organic amide for enhanced curing speed.
A reactive acrylic adhesive, activated by actinic radiation, includes at least about 0.1 percent by weight of a beta-unsaturated organic amide for enhanced curing speed.
Description
`~ ~2g~
Reactive acrylic adhesives are well known in the art, and are widely utilized due to the numerous advantageous char-acteristics that they exhibit. Curing of such adhesives may be c~ctivated by various chemical initiators, and the use of actinic S radiation (particularly in the ultraviolet region of the spectrum) has taken on considerable importance in recent years. Although compositions are commercially available which respond to UV and other actinic radiation to cure at high rates of speed, increased reactivity will generally be regarded to be advantageous, and will in fact be a fundamental criterion (together of course with appropriate adhesive, chemical and physical properties) for certain applications.
Accordingly, it is the broad object of the present in-vention to provide a novel reactive acrylic adhesive composition that is activated by radiation and that cures at high rates of speed to produce a tough and strong solid adhesive material.
It is also an object of the invention to provide a novel method for bonding surfaces utilizing such an adhesive composition.
It has now been found that certain of the foregoing and related objects of the invention are readily attained by the provision of a liquid composition comprising a major proportion of polymerizable acrylate monomer and a filler providing elastomeric domains, an effective amount of an actinic radiation-responsive photoinitiator, and at least about 0.1 percent, by weight of the composition, of a beta-unsaturated organic amide compound.
~k , ` ~2g7~Zl Preferably, the amide compound will be selected from the group consisting of dimethylaminopropyl methacrylamide, N,N-dimethyl-acrylamide, tert-butylacrylamide, tert-butylmethacrylamide, methyl-methacrylamide, butoxymethacrylamide, iso-butoxymethacrylamide, cyclohexylmethacrylamide, benzylmethacrylamide, methacrylamide, isooctyl acrylamide, acrylamide, diacetone acrylamide, p-hydro-xyacrylamidoaniline, N,N-methylene-bis-methacrylamide, 1,1,5,5-tetraacrylamidopentane, and N-methylene-bis acrylamide.
Generally, the filler employed will be a reactive acrylated polyurethane oligomer having a molecular weight of about 400 to 6000; preferably, it will be a diisocyanate-capped polyether acrylated by reaction with hydroxyethyl acrylate or methacrylate.
The acrylate monomer will preferably be isobornyl acrylate, hydro-xyethyl methacrylate, polyethyleneglycol dimethacrylate, tri-methylcyclohexyl acrylate, and mixtures of the foregoing. Phenylketones, such as l-hydroxycyclohexylphenyl ketone and 2,2-di-methoxy-2-phenyl acetophenone, will often be preferred for use as the photoinitiator.
The usual amounts of the ingredients of the composition will be about one to ten percent of the amide compound, about 30 to 60 percent of the monomer, about 5 to 60lpercent of the filler, and about one to five percent of the photoinitiator, all based upon the weight of the composition. In preferred embodiments, the composition will additionally include about two to six weight percent of acrylic acid.
Other objects of the invention are attained by the 129'7~iZl provision of a bonding method, in accordance with which the ad-hesive composition hereinabove described is applied to at least one of the surfaces to be bonded. After effecting contact between the surfaces, the composition is exposed to actinic radiation for a period of time sufficient to effect curing to an adhesive solid. The curing period will normally be less than about one minute, and curing times of less than ten seconds are possible and will be highly desirable for many applications. The method of the invention may be employed to effect bonding of preassembled parts between which the clearance is very small, in which case a viscosity-reducing capolymerizable monomer, such as methyl-methacrylate, may be incorporated into the composition. Altern-altively, the composition may be used for gap-filling and coating applications, in which case the inclusion of a thixotrope or thickening agent may be beneficial.
Exemplary of the efficacy of the present invention are the following examples:
Example One A series of adhesive compositions are prepared and tested;
the ingredients and amounts, in parts by weight, are set forth in Table One, which follows. Cure rates are determined by apply-ing a drop of the adhesive composition to a glass microscope slide, covering it with a second slide (in offset relationship), and applying finger pressure to distribute the adhesive (the amount of adhesive is sufficient to cover an area of about one square inch, when spread). The assembly is held at about the ~ . .
lZ9'7~2~
focal point of a focused medium-pressure mercury UV lamp having a measured intensity (at the focal point) of about 100 milliwatts per square centimeter (about 30 milliwatts per square centimeter of :365 nanometer radiation), and gentle to and fro shear force is manually applied to the slides along the shear plane. The period that elapses from initial exposure until relative movement is no longer possible is taken to be the curing time for the composition.
TABLE ONE
Formulation Designation Ingredient A B C D E F G H
Oligomer 1 12 7 10 6 Oligomer 2 5 4 Oligomer 3 12 10 Oligomer 4 12 10 Acrylic Acid Silane 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 IRGACURE 651 1.6 2.6 1.6 1.6 1.6 1.6 1.6 1.6 Amide - - - - 2 2 2 2 Cure Time (Sec.): 4 4 4 10 2 2 2 3 In the foregoing Table, the oligomers are all acrylated polyurethanes; oligomers "1", "3" and "4" are toluene diisocyanate-capped polypropylene glycol polyethers, acrylated by reactionwith hydroxyethyL acrylate, the molecular weight of the oligomer "1" polyether backbone being about 400, and the polyethers of oligomers "2" and "4" being the successive next higher homologues;
oligomer "2" is a product that is commercially available from Mila Company. The ingredient designated "IBOA" is isobornyl lZ976`2~
acrylate, "HEMA" is hydroxyethyl methacrylate, the silane is a typical glass adhesion promoter, IRGACURE 651 (a trade-mark used by Ciba-Geigy Company for its 2,2-dimethoxy-2-phenyl aceophenone photoinitiator), and the amide employed is dimethylaminopropyl methacrylaminde. As can be seen, sub-stitution of the amide for an equal weight of the oligomer effects a reduction in the cure time values of at least fifty percent. In all instances the physical and chemical proper-ties of the cured adhesives are found to be excellent.
ExamPle Two Substitution of an equal weight of IRGACURE 184 (a trade-mark of Ciba-Geigy Company for l-hydroxycyclohexy-phenyl ketone) for the IRGACURE 651 as the catalyst is found to provide comparable (but less dramatic) decrease~ in cure times, as compared to the amide-free formulations. The times for a series of compo~itions into which IRGACURE 184 is sub~tituted, but otherwise identical to formulations E-H, are 3,3,4 and 5 seconds, respectively.
Exam~le Three A series of compositions embodying the invention are prepared utilizing various beta-unsaturated organic amides.
The formulation con~ists of 15.7 parts of oligomer "1"
(Table One), 39.3 parts i~obornyl acrylate, 20.0 parts hydroxyethyl methacrylate, 4.0 parts IRGACURE 651, 2.5 parts of the silane, 20.0 parts triethyleneglycol di-acrylate, and 5.7 parts of the selected amide (all parts on a weight basis)~ The amides are : (1) dimethylamino-propyl methacrylamide (as used in Example~ One 297~i21 and Two), (2) iso-butoxymethacrylamide, (3) isooctyl acrylamide, (4) acrylamide, (5) diacetone acrylamide, (6) N,N-methylene-bis-methacrylamide, (7) 1,1,5,5-tetraacrylamido-pentane, and (8) N,N-methylene-bis-acrylamide. Cure is effected by exposure to a black light source, having a measured intensity at the bond line of about 0.1 milliwatt per square centimeter.
The formulations containing amides (1) an~-(3) both cure in about six seconds; the remaining formulations cure in about five seconds, and all of the cured adhesives exhibit excellent properties. Thus, beta-unsaturated amides in general are seen to be effective cure accelerators in these compositions, and it will be appreciated by those skilled in the art that any of numerous other amides may be employed to good advantage, such as N,N-dimethyl acrylamide, tert-butylacrylamide, tert-butylmeth-acrylamide, methylmethacrylamide, butoxymethacrylamide, cyclo-hexyl methacrylamide, benzylmethacrylamide and methacrylamide.
Example Four The adhesive composition of Example One is modified by substituting an equivalent amount of camphroquinone for the IRGACURE 651 photoinitiator employed therein, to render the com-position responsive to radiation in the visible range. Results comparable to those reported above are achieved upon exposure to such light (filtered to block UV radiation) under the conditions descriked, with the amide-modified compositions exhibiting sub-stantially faster cure speeds than those from which theingredient is omitted.
-` 129~76Zl Example Five An adhesive composition is prepared by admixing 480 parts of an oligomer prepared by acrylating with HENA a 4000 molecular weight, toluene diisocyanate-capped polypropylene glycol polyether, 210 parts of IBOA, 70 parts HEMA, 20 parts IRGACURE 651, 12 parts maleic acid, 12 parts silane, and 1.5 parts phenolic antioxidant, all on a weight basis. A second compo~ition is prepared from the same amounts of the same ingredients, but additionally including about 45 parts of dimethylaminopropyl methacrylamide. A quantity of each composition is spread upon one surface of a painted, flexible steel measuring rule blade, and a strip of 5 mil Mylar (a trade-mark) film is applied over the adhesive, following which the assembly is exposed at the focus point of the UV
radiation source described in connection with Example One.
The blade is then bent back upon itself and flattened until it snaps; the adhesive is deemed satisfactory if the Mylar film simultaneously fractures, and unsatisfactory if instead delamination occurs.
Exposure of the samples for 10 seconds produces a positive (film-fracturing bond) only with the amide-contain-ing composition; the unmodified adhesive fails after either 10 or 15 seconds exposure, and requires 20 seconds in the actinic radiation beam to produce such a result.
The acrylate monomer employed in the instant compo~i-tions will generally be a reaction product of acrylic acid and/or methacrylic acid with one or more mono- or polybasic, substituted or unsubstituted, alkyl (Cl to Cl 8 ), aryl or aralkyl alcohols.
' ~ -7-129~iZl Preferred acrylates will often be those in which the alcohol moiety contains a polar substituent (e.g., an hydroxyl, amine, halogen, cyano, heterocyclic or cyclohexyl group), ~ince cross-linking or other intermolecular bonding is promoted thereby. General disclosure of suitable acrylic ester monomers are provided in the prior art, such as in United States Patent Nos. 3,21~,305 (line 65, column 1 through line 47, column 2)' 3,425,988 (line 49, column 2 through line 21, column 3); 3,651,036 (line 69, column 1 through line 12, column 2); 3,658,624 (line 74, column 1 through line 58, column 2); 3,826,756 (line 49, column 2 throu~h line 5, column 3); and 3,855,040 (line 20, column 3 through line 55, column 4). It is believed that the choice of appropriate ester monomers will be evident to those sXilled in the art, and that further ~eneralized description thereof will therefore be unnecessary.
Nevertheless, it might be pointed out that specific acrylates which can advantageously be employed, alone or in combination, include (in addition to the HEMA and IBOA used in the foregoing Examples) the tetraethylene-~lycol, isodecyl and hydroxyethyl esters of acrylic acid;
the butyl, isodecyl, methyl, tetrahydrofurfuryl, isobornyl, and dicyclopentadienyl esters of methacrylic acid; di-acrylates, triacrylates and tetracrylates (i.e., the poly-acrylic and polymethacrylic esters) of butyleneglycol, ,~ -8-lZ9762~
triethyleneglycol, tetraethyleneglycol, polyethylene ~lycol r bisphenol A, pentaerythritol (particularly the triacrylate e~ster), trimethylcyclohexyl acrylate, and the like.
Turning now more specifically to the filler, virtually any material that is soluble (to at least a significant degree) in the monomer fraction, and that services to toughen, flexi-bilize, and/or strengthen the cured adhesive, ~ay be used. The filler need not be introduced as a rubbery solid; liquids and waxy substances are also entirely suitable. It is most desira-ble that the filler be reactive with the monomeric components to produce intermolecular bonding, since that will enhance compatibility and tend to maximize the ultimate properties of the adhesive. In any event, it is believed that the effective fillers toughen or otherwise desirably modify the adhesive by dispersin~ in the monomer formulation to provide elastomeric domains: generally, they will be rubbery or elastomeric materials, thermoplastic polymers, or macromers.
Although the selection of specific appropriate elasto-meric domain-providin~ fillers will be evident to those skilled in the art, it mi~ht be mentioned that typical ~uitable materials include vinyl polymers, acrylic polymers, polyester elastomers, glycol polymers, acrylated epoxies, natural and synthetic rubbers, and the like. More particularly, fillers such as VINAC B-7 (a trade-mark for polyvinyl acetate sold by Airco Chemical Company), polyethyleneglycol 6000, HYCAR CTBN
and HYCAR 1022 (trade-mar~s for liquid rubbers sold by B.F.
Goodrich Chemical Company), X-80 (polyester oli~omer sold by v ,p~ _g_ . . .
.
1297~i21 Union Carbide Corporation), and KM-229, KM-288 and RM-323B
(acrylic elastomers sold by the Rohn & Haas Company) are advantageously used in the formulations of the invention.
In many instances, however, the urethane polymers and prepolymers will be preferred, with the latter being especially desirable due to the potential that they afford for further reaction of their pendant isocyanate groups with a reactive functionality (e.g., an hydroxyl group) provided by a suitable acrylate monomer. Typical specific urethane elastomers that are advantageously used include the rubber sold by B.F. Good-rich Chemical Company under the trade-mark ESTANE 5730, and the prepolymers sold respectively by Witco Chemical Company and by N.L. Industries under the trade-marks CASTOMER 0002 and VORITE.
Particularly preferred are ~uch urethanes capped with an acrylic monomer, e.g., the oligomers used in the foregoing Example~, and the polyacrylate esters of organic polyisocyan-ates described as "monomers" in the above-mentioned United States Patent No. 3,425,988. In view of all of the foregoing, however, it will be appreciated that the selection of a par-ticular elastomeric domain-providing filler is not critical, and that the specific material used may vary widely, depending upon the application for, and the properties desired in, the adhesive.
The amount of filler utilized will depend upon several ... .
lZ97~21 factors, including again the properties desired in the ultimate product, the nature of the components employed, and the like.
Generally, at least about five weight percent will be employed, and in the preferred compositions the filler will usually constitute about 20 to 50 weight percent.
As will be appreciated, a primary feature of the instant compositions resides in the use of the beta-unsaturated organic amide constituent, the incorporation of which has been found to produce a surprising increase in curing speed; typically, the modified adhesives cure 25 to 50 percent faster than the same compositions without the amide, as discussed above with reference to the Examples. It is believed that virtually any such amide that is substantially soluble in the formulation can be employed to good effect, be it mono- or polyfunctional, and a list of exemplary compounds has been set forth hereinabove.
However, the monofunctional amide will often provide the fastest cure rates and prove to be effective in the lowest concentrations;
they will therefore generally be preferred over the polyfunctional compounds. Dimethylaminopropyl methacrylamide has been found to be particularly effective, and to produce substantial decreases in cure times in concentrations as low as 0.1 percent by weight of the composition.
It has also been found that virtually any compatible photoinitiator may be employed in the instant compositions, and appropriate compounds will be evident to those skilled in the art. Nevertheless, it might be noted that l-hydroxycyclo-lZ~7~21 hexylphenyl ketone, 2,2-dimethoxy-2-phenyl acetophenone, diethoxy acetophenone, and 2-methyl-1-(methylethiophenyl~-2-(4-morpho-linyl)-l-propanone can be used to good effect for response to actinic radiation in the UV range, and camphroquinone and suitably sensitized compositions using the above-listed photoinitiators can, for example, be employed in visible-light reactive systems;
other appropriate initiators include benzophenone, benzil, tetramethyldiaminobenzophenone (Michler's ketone), benzoin ethers, alpha,alpha-diethoxyacetophenone and ketocoumarins. Typically, about one to five weight percent, and preferably about four percent, of the photoinitiator will be employed.
In addition to the principal components hereinabove described, it will be evident that other materials may also be incorporated into the instant compositions. For example, acrylic acid, used in the amounts indicated, is especially desirable from the standpoint of maximizing adhesion and curing rate; "inert"
fillers, such as wood flour, glass fibers, cotton linters, mica, alumina, silica, and the like, are conventionally used to modify viscosity, improve impact resistance, and for other purposes, and they may be employed in the instant compositions if so desired.
It is also conventional to include small perce~tages of silane monomers to increase moisture resistance as well as to enhance the bond strength of the adhesive to glass and similar surfaces.
Other substances, such as dyes, fire retarders, stabilizers (e.g.
the quinones and hydroquinones), thixotropes, thickeners, viscosity reducers, plasticizers, antioxidants, and the like, may additionally ~2976~i be incorporated, although it will be appreciated that such additives will often be furnished in the principal ingredients, making their separate introduction unnecessary.
Despite the fact that all of the compositions of the S invention exhibit adhesive properties, it will of course be under-stood that they can be used for other purposes as well. For example, they may serve as coatings, for applications in which gap-filling is of primary importance, etc.
Thus, it can be seen that the present invention provides a novel reactive acrylic adhesive composition that is activated by actinic radiation and that cures at high rates of speed to produce a tough and strong solid adhesive material. The invention also provides a novel method for bonding surfaces utilizing such an adhesive composition.
.
Reactive acrylic adhesives are well known in the art, and are widely utilized due to the numerous advantageous char-acteristics that they exhibit. Curing of such adhesives may be c~ctivated by various chemical initiators, and the use of actinic S radiation (particularly in the ultraviolet region of the spectrum) has taken on considerable importance in recent years. Although compositions are commercially available which respond to UV and other actinic radiation to cure at high rates of speed, increased reactivity will generally be regarded to be advantageous, and will in fact be a fundamental criterion (together of course with appropriate adhesive, chemical and physical properties) for certain applications.
Accordingly, it is the broad object of the present in-vention to provide a novel reactive acrylic adhesive composition that is activated by radiation and that cures at high rates of speed to produce a tough and strong solid adhesive material.
It is also an object of the invention to provide a novel method for bonding surfaces utilizing such an adhesive composition.
It has now been found that certain of the foregoing and related objects of the invention are readily attained by the provision of a liquid composition comprising a major proportion of polymerizable acrylate monomer and a filler providing elastomeric domains, an effective amount of an actinic radiation-responsive photoinitiator, and at least about 0.1 percent, by weight of the composition, of a beta-unsaturated organic amide compound.
~k , ` ~2g7~Zl Preferably, the amide compound will be selected from the group consisting of dimethylaminopropyl methacrylamide, N,N-dimethyl-acrylamide, tert-butylacrylamide, tert-butylmethacrylamide, methyl-methacrylamide, butoxymethacrylamide, iso-butoxymethacrylamide, cyclohexylmethacrylamide, benzylmethacrylamide, methacrylamide, isooctyl acrylamide, acrylamide, diacetone acrylamide, p-hydro-xyacrylamidoaniline, N,N-methylene-bis-methacrylamide, 1,1,5,5-tetraacrylamidopentane, and N-methylene-bis acrylamide.
Generally, the filler employed will be a reactive acrylated polyurethane oligomer having a molecular weight of about 400 to 6000; preferably, it will be a diisocyanate-capped polyether acrylated by reaction with hydroxyethyl acrylate or methacrylate.
The acrylate monomer will preferably be isobornyl acrylate, hydro-xyethyl methacrylate, polyethyleneglycol dimethacrylate, tri-methylcyclohexyl acrylate, and mixtures of the foregoing. Phenylketones, such as l-hydroxycyclohexylphenyl ketone and 2,2-di-methoxy-2-phenyl acetophenone, will often be preferred for use as the photoinitiator.
The usual amounts of the ingredients of the composition will be about one to ten percent of the amide compound, about 30 to 60 percent of the monomer, about 5 to 60lpercent of the filler, and about one to five percent of the photoinitiator, all based upon the weight of the composition. In preferred embodiments, the composition will additionally include about two to six weight percent of acrylic acid.
Other objects of the invention are attained by the 129'7~iZl provision of a bonding method, in accordance with which the ad-hesive composition hereinabove described is applied to at least one of the surfaces to be bonded. After effecting contact between the surfaces, the composition is exposed to actinic radiation for a period of time sufficient to effect curing to an adhesive solid. The curing period will normally be less than about one minute, and curing times of less than ten seconds are possible and will be highly desirable for many applications. The method of the invention may be employed to effect bonding of preassembled parts between which the clearance is very small, in which case a viscosity-reducing capolymerizable monomer, such as methyl-methacrylate, may be incorporated into the composition. Altern-altively, the composition may be used for gap-filling and coating applications, in which case the inclusion of a thixotrope or thickening agent may be beneficial.
Exemplary of the efficacy of the present invention are the following examples:
Example One A series of adhesive compositions are prepared and tested;
the ingredients and amounts, in parts by weight, are set forth in Table One, which follows. Cure rates are determined by apply-ing a drop of the adhesive composition to a glass microscope slide, covering it with a second slide (in offset relationship), and applying finger pressure to distribute the adhesive (the amount of adhesive is sufficient to cover an area of about one square inch, when spread). The assembly is held at about the ~ . .
lZ9'7~2~
focal point of a focused medium-pressure mercury UV lamp having a measured intensity (at the focal point) of about 100 milliwatts per square centimeter (about 30 milliwatts per square centimeter of :365 nanometer radiation), and gentle to and fro shear force is manually applied to the slides along the shear plane. The period that elapses from initial exposure until relative movement is no longer possible is taken to be the curing time for the composition.
TABLE ONE
Formulation Designation Ingredient A B C D E F G H
Oligomer 1 12 7 10 6 Oligomer 2 5 4 Oligomer 3 12 10 Oligomer 4 12 10 Acrylic Acid Silane 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 IRGACURE 651 1.6 2.6 1.6 1.6 1.6 1.6 1.6 1.6 Amide - - - - 2 2 2 2 Cure Time (Sec.): 4 4 4 10 2 2 2 3 In the foregoing Table, the oligomers are all acrylated polyurethanes; oligomers "1", "3" and "4" are toluene diisocyanate-capped polypropylene glycol polyethers, acrylated by reactionwith hydroxyethyL acrylate, the molecular weight of the oligomer "1" polyether backbone being about 400, and the polyethers of oligomers "2" and "4" being the successive next higher homologues;
oligomer "2" is a product that is commercially available from Mila Company. The ingredient designated "IBOA" is isobornyl lZ976`2~
acrylate, "HEMA" is hydroxyethyl methacrylate, the silane is a typical glass adhesion promoter, IRGACURE 651 (a trade-mark used by Ciba-Geigy Company for its 2,2-dimethoxy-2-phenyl aceophenone photoinitiator), and the amide employed is dimethylaminopropyl methacrylaminde. As can be seen, sub-stitution of the amide for an equal weight of the oligomer effects a reduction in the cure time values of at least fifty percent. In all instances the physical and chemical proper-ties of the cured adhesives are found to be excellent.
ExamPle Two Substitution of an equal weight of IRGACURE 184 (a trade-mark of Ciba-Geigy Company for l-hydroxycyclohexy-phenyl ketone) for the IRGACURE 651 as the catalyst is found to provide comparable (but less dramatic) decrease~ in cure times, as compared to the amide-free formulations. The times for a series of compo~itions into which IRGACURE 184 is sub~tituted, but otherwise identical to formulations E-H, are 3,3,4 and 5 seconds, respectively.
Exam~le Three A series of compositions embodying the invention are prepared utilizing various beta-unsaturated organic amides.
The formulation con~ists of 15.7 parts of oligomer "1"
(Table One), 39.3 parts i~obornyl acrylate, 20.0 parts hydroxyethyl methacrylate, 4.0 parts IRGACURE 651, 2.5 parts of the silane, 20.0 parts triethyleneglycol di-acrylate, and 5.7 parts of the selected amide (all parts on a weight basis)~ The amides are : (1) dimethylamino-propyl methacrylamide (as used in Example~ One 297~i21 and Two), (2) iso-butoxymethacrylamide, (3) isooctyl acrylamide, (4) acrylamide, (5) diacetone acrylamide, (6) N,N-methylene-bis-methacrylamide, (7) 1,1,5,5-tetraacrylamido-pentane, and (8) N,N-methylene-bis-acrylamide. Cure is effected by exposure to a black light source, having a measured intensity at the bond line of about 0.1 milliwatt per square centimeter.
The formulations containing amides (1) an~-(3) both cure in about six seconds; the remaining formulations cure in about five seconds, and all of the cured adhesives exhibit excellent properties. Thus, beta-unsaturated amides in general are seen to be effective cure accelerators in these compositions, and it will be appreciated by those skilled in the art that any of numerous other amides may be employed to good advantage, such as N,N-dimethyl acrylamide, tert-butylacrylamide, tert-butylmeth-acrylamide, methylmethacrylamide, butoxymethacrylamide, cyclo-hexyl methacrylamide, benzylmethacrylamide and methacrylamide.
Example Four The adhesive composition of Example One is modified by substituting an equivalent amount of camphroquinone for the IRGACURE 651 photoinitiator employed therein, to render the com-position responsive to radiation in the visible range. Results comparable to those reported above are achieved upon exposure to such light (filtered to block UV radiation) under the conditions descriked, with the amide-modified compositions exhibiting sub-stantially faster cure speeds than those from which theingredient is omitted.
-` 129~76Zl Example Five An adhesive composition is prepared by admixing 480 parts of an oligomer prepared by acrylating with HENA a 4000 molecular weight, toluene diisocyanate-capped polypropylene glycol polyether, 210 parts of IBOA, 70 parts HEMA, 20 parts IRGACURE 651, 12 parts maleic acid, 12 parts silane, and 1.5 parts phenolic antioxidant, all on a weight basis. A second compo~ition is prepared from the same amounts of the same ingredients, but additionally including about 45 parts of dimethylaminopropyl methacrylamide. A quantity of each composition is spread upon one surface of a painted, flexible steel measuring rule blade, and a strip of 5 mil Mylar (a trade-mark) film is applied over the adhesive, following which the assembly is exposed at the focus point of the UV
radiation source described in connection with Example One.
The blade is then bent back upon itself and flattened until it snaps; the adhesive is deemed satisfactory if the Mylar film simultaneously fractures, and unsatisfactory if instead delamination occurs.
Exposure of the samples for 10 seconds produces a positive (film-fracturing bond) only with the amide-contain-ing composition; the unmodified adhesive fails after either 10 or 15 seconds exposure, and requires 20 seconds in the actinic radiation beam to produce such a result.
The acrylate monomer employed in the instant compo~i-tions will generally be a reaction product of acrylic acid and/or methacrylic acid with one or more mono- or polybasic, substituted or unsubstituted, alkyl (Cl to Cl 8 ), aryl or aralkyl alcohols.
' ~ -7-129~iZl Preferred acrylates will often be those in which the alcohol moiety contains a polar substituent (e.g., an hydroxyl, amine, halogen, cyano, heterocyclic or cyclohexyl group), ~ince cross-linking or other intermolecular bonding is promoted thereby. General disclosure of suitable acrylic ester monomers are provided in the prior art, such as in United States Patent Nos. 3,21~,305 (line 65, column 1 through line 47, column 2)' 3,425,988 (line 49, column 2 through line 21, column 3); 3,651,036 (line 69, column 1 through line 12, column 2); 3,658,624 (line 74, column 1 through line 58, column 2); 3,826,756 (line 49, column 2 throu~h line 5, column 3); and 3,855,040 (line 20, column 3 through line 55, column 4). It is believed that the choice of appropriate ester monomers will be evident to those sXilled in the art, and that further ~eneralized description thereof will therefore be unnecessary.
Nevertheless, it might be pointed out that specific acrylates which can advantageously be employed, alone or in combination, include (in addition to the HEMA and IBOA used in the foregoing Examples) the tetraethylene-~lycol, isodecyl and hydroxyethyl esters of acrylic acid;
the butyl, isodecyl, methyl, tetrahydrofurfuryl, isobornyl, and dicyclopentadienyl esters of methacrylic acid; di-acrylates, triacrylates and tetracrylates (i.e., the poly-acrylic and polymethacrylic esters) of butyleneglycol, ,~ -8-lZ9762~
triethyleneglycol, tetraethyleneglycol, polyethylene ~lycol r bisphenol A, pentaerythritol (particularly the triacrylate e~ster), trimethylcyclohexyl acrylate, and the like.
Turning now more specifically to the filler, virtually any material that is soluble (to at least a significant degree) in the monomer fraction, and that services to toughen, flexi-bilize, and/or strengthen the cured adhesive, ~ay be used. The filler need not be introduced as a rubbery solid; liquids and waxy substances are also entirely suitable. It is most desira-ble that the filler be reactive with the monomeric components to produce intermolecular bonding, since that will enhance compatibility and tend to maximize the ultimate properties of the adhesive. In any event, it is believed that the effective fillers toughen or otherwise desirably modify the adhesive by dispersin~ in the monomer formulation to provide elastomeric domains: generally, they will be rubbery or elastomeric materials, thermoplastic polymers, or macromers.
Although the selection of specific appropriate elasto-meric domain-providin~ fillers will be evident to those skilled in the art, it mi~ht be mentioned that typical ~uitable materials include vinyl polymers, acrylic polymers, polyester elastomers, glycol polymers, acrylated epoxies, natural and synthetic rubbers, and the like. More particularly, fillers such as VINAC B-7 (a trade-mark for polyvinyl acetate sold by Airco Chemical Company), polyethyleneglycol 6000, HYCAR CTBN
and HYCAR 1022 (trade-mar~s for liquid rubbers sold by B.F.
Goodrich Chemical Company), X-80 (polyester oli~omer sold by v ,p~ _g_ . . .
.
1297~i21 Union Carbide Corporation), and KM-229, KM-288 and RM-323B
(acrylic elastomers sold by the Rohn & Haas Company) are advantageously used in the formulations of the invention.
In many instances, however, the urethane polymers and prepolymers will be preferred, with the latter being especially desirable due to the potential that they afford for further reaction of their pendant isocyanate groups with a reactive functionality (e.g., an hydroxyl group) provided by a suitable acrylate monomer. Typical specific urethane elastomers that are advantageously used include the rubber sold by B.F. Good-rich Chemical Company under the trade-mark ESTANE 5730, and the prepolymers sold respectively by Witco Chemical Company and by N.L. Industries under the trade-marks CASTOMER 0002 and VORITE.
Particularly preferred are ~uch urethanes capped with an acrylic monomer, e.g., the oligomers used in the foregoing Example~, and the polyacrylate esters of organic polyisocyan-ates described as "monomers" in the above-mentioned United States Patent No. 3,425,988. In view of all of the foregoing, however, it will be appreciated that the selection of a par-ticular elastomeric domain-providing filler is not critical, and that the specific material used may vary widely, depending upon the application for, and the properties desired in, the adhesive.
The amount of filler utilized will depend upon several ... .
lZ97~21 factors, including again the properties desired in the ultimate product, the nature of the components employed, and the like.
Generally, at least about five weight percent will be employed, and in the preferred compositions the filler will usually constitute about 20 to 50 weight percent.
As will be appreciated, a primary feature of the instant compositions resides in the use of the beta-unsaturated organic amide constituent, the incorporation of which has been found to produce a surprising increase in curing speed; typically, the modified adhesives cure 25 to 50 percent faster than the same compositions without the amide, as discussed above with reference to the Examples. It is believed that virtually any such amide that is substantially soluble in the formulation can be employed to good effect, be it mono- or polyfunctional, and a list of exemplary compounds has been set forth hereinabove.
However, the monofunctional amide will often provide the fastest cure rates and prove to be effective in the lowest concentrations;
they will therefore generally be preferred over the polyfunctional compounds. Dimethylaminopropyl methacrylamide has been found to be particularly effective, and to produce substantial decreases in cure times in concentrations as low as 0.1 percent by weight of the composition.
It has also been found that virtually any compatible photoinitiator may be employed in the instant compositions, and appropriate compounds will be evident to those skilled in the art. Nevertheless, it might be noted that l-hydroxycyclo-lZ~7~21 hexylphenyl ketone, 2,2-dimethoxy-2-phenyl acetophenone, diethoxy acetophenone, and 2-methyl-1-(methylethiophenyl~-2-(4-morpho-linyl)-l-propanone can be used to good effect for response to actinic radiation in the UV range, and camphroquinone and suitably sensitized compositions using the above-listed photoinitiators can, for example, be employed in visible-light reactive systems;
other appropriate initiators include benzophenone, benzil, tetramethyldiaminobenzophenone (Michler's ketone), benzoin ethers, alpha,alpha-diethoxyacetophenone and ketocoumarins. Typically, about one to five weight percent, and preferably about four percent, of the photoinitiator will be employed.
In addition to the principal components hereinabove described, it will be evident that other materials may also be incorporated into the instant compositions. For example, acrylic acid, used in the amounts indicated, is especially desirable from the standpoint of maximizing adhesion and curing rate; "inert"
fillers, such as wood flour, glass fibers, cotton linters, mica, alumina, silica, and the like, are conventionally used to modify viscosity, improve impact resistance, and for other purposes, and they may be employed in the instant compositions if so desired.
It is also conventional to include small perce~tages of silane monomers to increase moisture resistance as well as to enhance the bond strength of the adhesive to glass and similar surfaces.
Other substances, such as dyes, fire retarders, stabilizers (e.g.
the quinones and hydroquinones), thixotropes, thickeners, viscosity reducers, plasticizers, antioxidants, and the like, may additionally ~2976~i be incorporated, although it will be appreciated that such additives will often be furnished in the principal ingredients, making their separate introduction unnecessary.
Despite the fact that all of the compositions of the S invention exhibit adhesive properties, it will of course be under-stood that they can be used for other purposes as well. For example, they may serve as coatings, for applications in which gap-filling is of primary importance, etc.
Thus, it can be seen that the present invention provides a novel reactive acrylic adhesive composition that is activated by actinic radiation and that cures at high rates of speed to produce a tough and strong solid adhesive material. The invention also provides a novel method for bonding surfaces utilizing such an adhesive composition.
.
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A liquid composition of high-speed reaction to a solid adhesive when exposed to actinic radiation, comprising a major proportion of at least one polymerizable acrylate monomer and an elastomer domain-providing filler, an effective amount of an actinic radiation-response photoinitiator, and at least about 0.1 percent, by weight of said composition, of an amide com-pound selected from the group consisting of dimethylaminopropyl methacrylamide, methylmethacrylamide, iso-butoxymethacrylamide, cyclohexylmethacrylamide, methacrylamide, isooctyl acrylamide, acrylamide, diacetone acrylamide, p-hydroxyacrylamidoaniline, N,N-methylene-bis-methacrylamide, 1,1,5,5-tetraacrylamidopen-tane, and N,N-methylene-bis-acrylamide.
2. The composition of Claim 1 wherein said filler is an acrylated polyurethane oligomer.
3. The composition of CLaim 2 wherein said oligomer has a molecular weight of about 400 to 6000, and is a diisocyanate-capped polyether acrylated by reaction with hydroxyethyl acrylate or hydroxyethyl methacrylate.
4. The composition of Claim 1 wherein said acrylate monomer is a compound selected from the group consisting of isobornyl acrylate, hydroxyethyl methacrylate, polyethylene-glycol dimethacrylate, trimethylcyclohexyl acrylate, and mixtures thereof.
5. The composition of Claim 1 wherein said photoinitiator is a compound selected from the group of diethoxy acetophenone, 1-hydroxy-cyclohexylphenyl ketone, 2-methyl-1-(methyl-thiophenyl)-2-(4-morpholinyl)-1-propanone, and 2,2-dimethoxy-2-phenyl acetophenone.
6. The composition of Claim 5 wherein said actinic radiation to which said photoinitiator responds is in the ultraviolet range.
7. The composition of Claim 1 wherein said actinic radiation to which said photoinitiator responds is in the visible range.
8. The composition of Claim 1 wherein additionally including about two to six percent by weight thereof of acrylic acid.
9. The composition of Claim 1 wherein said photoinitiator constitutes about one to five percent by weight thereof.
10. The composition of Claim 9 wherein the amount of said amide compound is about one to ten percent by weight of said composition.
11. The composition of CLaim 10 wherein said monomer and filler constitute about 30 to 60 and 5 to 60 weight percent of said composition, respectively.
12. A liquid composition of high-speed reaction to a solid adhesive when exposed to actinic radiation, comprising about 30 to 60 percent of at least one polymerizable acrylate monomer, about 5 to 60 percent of an acrylated polyurethane oligomer having a molecular weight of about 400 to 6000, about one to five percent of an actinic radiation-response photo-initiator, about two to six percent of acrylic acid, and about 0.1 to ten percent of an amide compound selected from the group consisting of dimethylaminopropyl methacrylamide, methyl-methacrylamide, iso-butoxymethacrylamide, cyclohexylmethacryl-amide, methacrylamide, isooctyl acrylamide, acrylamide, diace-tone acrylamide, p-hydroxyacrylamidoaniline, N,N-methylene-bis-methacrylamide, 1,1,5,5-tetraacrylamidopentane, and N,N-methy-lene-bis-acrylamide, all based upon the weight of said composi-tion.
13. The composition of Claim 12 wherein said acrylate monomer is a compound selected from the group consisting of isobornyl acrylate, hydroxyethyl methacrylate, polyethylene-glycol dimethacrylate, trimethylcyclohexyl acrylate, and mixtures thereof.
14. In a method for bonding surfaces to one another, the steps comprising:
(a) providing a liquid composition of high-speed reac-tion to a solid adhesive when exposed to actinic radiation comprising a major proportion of at least one polymerizable acrylate monomer and an elastomer domain-providing filler, an effective amount of an actinic radiation-response photoinitia-tor, and at least about 0.1 percent, by weight of said composi-tion, of an amide compound selected from the group consisting of dimethylaminopropyl methacrylamide, methylmethacrylamide, iso-butoxymethacrylamide, cyclohexylmethacrylamide, methacryl-amide, isooctyl acrylamide, acrylamide, diacetone acrylamide, p-hydroxyacrylamidoaniline, N,N-methylene-bis-methacrylamide, 1,1,5,5-tetraacrylamidopentane, and N,N-methylene-bis-acryl-amide.
(b) applying said composition to at least one of the surfaces to be bonded, and effecting contact of another surface therewith; and (c) exposing said composition between said surfaces to actinic radiation for a period of time sufficient to effect curing of said composition to an adhesive solid.
(a) providing a liquid composition of high-speed reac-tion to a solid adhesive when exposed to actinic radiation comprising a major proportion of at least one polymerizable acrylate monomer and an elastomer domain-providing filler, an effective amount of an actinic radiation-response photoinitia-tor, and at least about 0.1 percent, by weight of said composi-tion, of an amide compound selected from the group consisting of dimethylaminopropyl methacrylamide, methylmethacrylamide, iso-butoxymethacrylamide, cyclohexylmethacrylamide, methacryl-amide, isooctyl acrylamide, acrylamide, diacetone acrylamide, p-hydroxyacrylamidoaniline, N,N-methylene-bis-methacrylamide, 1,1,5,5-tetraacrylamidopentane, and N,N-methylene-bis-acryl-amide.
(b) applying said composition to at least one of the surfaces to be bonded, and effecting contact of another surface therewith; and (c) exposing said composition between said surfaces to actinic radiation for a period of time sufficient to effect curing of said composition to an adhesive solid.
15. The method of Claim 14 wherein, in said composition said filler is an acrylated polyurethane oligomer.
16. The method of Claim 15 wherein, in said composition said oligomer has a molecular weight of about 400 to 6000 and is a diisocyanate-capped polyether acrylated by reaction with hydroxyethyl acrylate or hydroxyethyl methacrylate.
17. The method of Claim 14 wherein, in said composition said acrylate monomer is a compound selected from the group consisting of isobornyl acrylate, hydroxyethyl methacrylate, polyethyleneglycol dimethacrylate, trimethycyclohexyl acrylate, and mixtures thereof.
18. The method of Claim 14 wherein, in said composition said photoinitiator is a compound selected from the group consisting of diethoxy acetophenone, 1-hydroxy-cyclohexylphenyl ketone, 2-methyl-1-(methylthiphenyl)-2-(4-morpholinyl)-1-propanone, and 2,2-dimethoxy-2-phenyl acetophenone.
19. The method of Claim 14 wherein said composition additionally includes about two to six percent by weight thereof of acrylic acid.
20. The method of Claim 14 wherein, in said composition the amount of said amide compound is about one to ten percent, said monomers and filler constitute about 30 to 60 and 5 to 60 percent, respectively, and said photoinitiator constitutes about one to five percent, all by weight of said composition;
and wherein said period of time of exposure is less than ten seconds, the radiation dose being equivalent to 30 milliwatts per square centimeter of radiation of selected wavelength.
and wherein said period of time of exposure is less than ten seconds, the radiation dose being equivalent to 30 milliwatts per square centimeter of radiation of selected wavelength.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US854987A | 1987-01-29 | 1987-01-29 | |
| US008,549 | 1987-01-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1297621C true CA1297621C (en) | 1992-03-17 |
Family
ID=21732227
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000557766A Expired - Fee Related CA1297621C (en) | 1987-01-29 | 1988-01-29 | Radiation-cured adhesive system containing amides |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS63225673A (en) |
| AU (1) | AU1299388A (en) |
| CA (1) | CA1297621C (en) |
| WO (1) | WO1988005791A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2585370B2 (en) * | 1988-05-18 | 1997-02-26 | 富士重工業株式会社 | Clamp mechanism in the dish picker |
| JP5956325B2 (en) * | 2012-12-13 | 2016-07-27 | 富士フイルム株式会社 | Curable composition and polymerizable compound |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3862021A (en) * | 1972-02-17 | 1975-01-21 | Asahi Chemical Ind | Polymerizable compositions and laminated articles bonded |
| JPS5034966B2 (en) * | 1972-07-24 | 1975-11-12 | ||
| US4210713A (en) * | 1973-02-01 | 1980-07-01 | Nippon Paint Co., Ltd. | Photo-curable composition for coating containing an unsaturated urethane modified polymer |
| US4181752A (en) * | 1974-09-03 | 1980-01-01 | Minnesota Mining And Manufacturing Company | Acrylic-type pressure sensitive adhesives by means of ultraviolet radiation curing |
| US4131529A (en) * | 1976-06-05 | 1978-12-26 | Basf Aktiengesellschaft | Photoinitiators for photopolymerizable coating compositions |
| US4133909A (en) * | 1977-01-26 | 1979-01-09 | Mobil Oil Corporation | Radiation curable aqueous coatings |
| JPS5493026A (en) * | 1977-12-29 | 1979-07-23 | Teijin Ltd | Photosensitive adhesive |
| JPS584953A (en) * | 1981-07-01 | 1983-01-12 | Toshiba Corp | Semiconductor device |
| NZ205989A (en) * | 1982-11-05 | 1987-04-30 | Deltaglass Sa | Radiation curable, urethane acrylate-containing fluid adhesive compositions and glass laminates |
| NZ205990A (en) * | 1982-11-05 | 1987-04-30 | Deltaglass Sa | Radiation-curable, urethane acrylate-containing liquid adhesive composition and glass laminates |
-
1988
- 1988-01-27 JP JP1476688A patent/JPS63225673A/en active Pending
- 1988-01-28 AU AU12993/88A patent/AU1299388A/en not_active Abandoned
- 1988-01-28 WO PCT/US1988/000252 patent/WO1988005791A1/en unknown
- 1988-01-29 CA CA000557766A patent/CA1297621C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU1299388A (en) | 1988-08-24 |
| WO1988005791A1 (en) | 1988-08-11 |
| JPS63225673A (en) | 1988-09-20 |
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