Abstract:
A method and means for bonding an object to a surface use emitted light from a chemiluminescent source to cure a photo-curable adhesive. This non-electrical source of light cures different photo-curable adhesives which can be tuned to different wavelengths of light emitted by different chemiluminescent sources. The curing is relatively quick and requires no electrical lighting in a wide range of environmental conditions, including under water and in air, with little or no ancillary support. An inexpensive and expendable photo-curable adhesive system is provided which is greatly simplified as compared to electrically powered curing systems.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
     BACKGROUND OF THE INVENTION 
     This invention relates to adhesives for bonding objects together. In particular, this invention relates to curing photo-curable adhesives using light radiated from sources of chemiluminescent light in a variety of environments. 
     A wide variety of adhesives for joining objects together have been developed for many different tasks. Some adhesives are premixed and, after application, only need to be exposed to air for a while to cure. Others are mixed with catalysts or other compounds to initiate and speed the curing process. Generally speaking, conventional two-part adhesive mixtures have been sluggish and ineffective in cold seawater temperatures. 
     Adhesive compounds have been developed that initiate curing when they are radiated by light from an electric lamp. The light radiated from the lamps may be not only visible light, but other wavelengths, such as ultraviolet or infrared. Because of the disadvantages associated with radiating light underwater from lamps, contemporary electric light cured adhesives have been largely used in air. Efforts have been made to utilize light from an electrically driven LED (light emitting diode) to cure adhesives, however, this approach uses electrical energy to light the LED&#39;s while the adhesive cures. In addition, the use of electrical energy makes curing more expensive and complicated, and requires additional logistical support. 
     Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for bonding systems that utilize chemiluminescent light sources to cure photo-curable adhesives quickly under water and in air, and do not require any electrical lighting. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to providing a bonding system including a source of chemiluminescent light and a photo-curable adhesive cured by the radiated chemiluminescent light. 
     An object of the invention is to provide a system to cure photo-curable adhesives utilizing chemical sources of light. 
     Another object of the invention is to provide a system to adhesively bond objects underwater or in air using photo-curable adhesives and no ancillary electrical power. 
     Another object of the invention is to provide a system utilizing non-electrical sources of light for curing photo-curable adhesives. 
     Another object of the invention is to provide a system to bond objects under water or in air using fewer components. 
     Another object of the invention provides bonding using chemical light for producing cure in photo-curable adhesives. 
     Another object of the invention is to provide a system to cure photo-curable adhesive on demand by initiation of chemiluminescent reaction. 
     Another object of the invention is to provide a system having chemiluminescent sources of light emitting at different wavelengths of light to cure different photo-curable adhesives. 
     Another object is to provide systems having photo-curable methacrylate adhesives tunable to chemiluminescent light sources. 
     Another object of the invention is to provide systems having photo-curable epoxy tunable to chemiluminescent light sources. 
     Another object of the invention is to provide a system to cure photo-curable adhesive by breaking a membrane in a chemiluminescent module to initiate chemiluminescent reaction. 
     Another object of the invention is to provide a system to cure photo-curable adhesive mixing one chemical compound with another chemical compound in a chemiluminescent module to initiate chemiluminescent reaction. 
     Another object of the invention is to provide a system to cure photo-curable adhesive by injecting one chemical compound into another chemical compound in a chemiluminescent module to initiate chemiluminescent reaction. 
     Another object of the invention is to provide a system to cure photo-curable adhesives in a wide range of environmental conditions with little to no ancillary support. 
     Another object of the invention is to provide a system to cure photo-curable adhesives using chemically initiated radiation that is inexpensive and expendable. 
     Another object of the invention is to provide a system for curing photo-curable adhesives with chemically initiated radiation to repair underwater structure, such as the hull of a boat with the photo-curable adhesive. 
     These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of an assembled chemiluminescent light curing system having a covered photo-curable adhesive and being transported to a submerged surface. 
     FIG. 2 shows the chemiluminescent curing system prior to being bonded to a surface by the photo-curable adhesive. 
     FIG. 3 shows another embodiment of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the drawings, chemiluminescent curing, or bonding system  10  provides the capability for bonding object  20  onto mounting surface  60 . The bonding of this invention is particularly useful not only for underwater applications but also for air and other environments where surfaces and/or objects need to be bonded together. Surface  60  is shown as facing up, but it could be differently oriented. 
     Object  20  could be many different things that are useful underwater, such as sensors, ordnance, structural members, navigational aids, etc. Bonding system  10  has object  20  in housing  11  to help provide structural integrity and protect object  20  from surrounding water. Housing  11  may have interior reflective surface  11   a  to expedite curing by reflecting chemiluminescent light. Elongate tabs  12  extending downwardly from housing  11  have end portions  12   a  crimped inwardly to hold modular-like chemiluminescent light source  30 , transparent chemical barrier  40 , and photo-curable adhesive  50  of system  10  together in a compact package. 
     Flexible, shell-shaped push-button  13  extends above housing  11  and may be deformed by the pressure exerted by a finger. Push button  13  has portion  14  extending through an opening provided in housing  11  and object  20 . Portion  14  may be either piston or blade-shaped, or one or more rotatable rigid protuberances, etc. 
     Looking to FIG. 2, deformation of push-button  13  displaces the piston, blade, rotatable protuberances, etc. to rupture membrane  31  in chemiluminescent light source  30  by breaking, cutting, or tearing it. The ruptured membrane  31  causes chemical compounds that were separated by membrane  31  to contact each another and to be at least partially mixed. This triggers, or initiates a chemiluminescent (chemical light) reaction in source  30  so that light is created and emitted. Photo-curable adhesive  50  begins to cure as its photo initiator is energized by irradiation from chemiluminescent light source  30 . In other words, emitted light energizes, i.e., initiates and maintains, curing in photo-curable adhesive  50 . 
     Push-button  13  also could be a plunger on a hypodermic needle-like structure. This structure injects a chemical compound of chemiluminescent light source module  30  into a container of another chemical compound of chemiluminescent light source module  30  to initiate a chemiluminescent reaction in source  30  to create and emit light. Furthermore, push-button  13  also could be a valve-like mechanism that would open a passageway or orifice between separated envelopes of different chemicals of chemiluminescent light source  30 . This enables mixing of these chemicals to initiate chemiluminescent reaction in source  30  to produce light. Other mixing techniques also may be used. 
     Use of the term light as discussed herein is intended to include any or all of infrared light, visible light, or ultraviolet light that may be produced or used. Furthermore, in accordance with this inventive concept, other radiations from appropriate chemical or non-electric sources of electromagnetic radiation could be utilized which are appropriate to energize the photo initiator in the selected radiation-curable adhesive. 
     Tabs  12  optionally may have elongate parts suitably configured to frictionally engage chemiluminescent light source  30 , transparent chemical barrier  40 , and photo-curable adhesive  50 , and/or may have their end parts shaped to engage mating parts on surface  60 . Irrespective which fastening arrangement is chosen, transparent chemical barrier  40  is sandwiched between chemiluminescent light source  30  and photo-curable adhesive  50 . A further option is that a length of reinforced tape or wire mesh may be tightly wrapped about the periphery of housing  11 , chemiluminescent light source  30 , transparent chemical barrier  40 , and photo-curable adhesive  50  to hold them together. 
     For some applications, bonding system  10  might not have the modules of chemiluminescent light source  30 , chemical barrier  40 , and photo-curable adhesive  50  layered and substantially parallel with one another as shown in the drawings. These modules may be differently arranged with respect to each other, and chemical barrier  40  may not need to be interposed. For example, chemiluminescent light source  30 , might be wrapped about the outside, or otherwise disposed so that enough of its chemically generated light can impinge upon and chemically initiate and maintain curing in photo-curable adhesive  50 . Noting FIG. 3, another arrangement for bonding system  10  is that photo-curable adhesive module  50  may be directly attached to object  20 . A technician, or diver will bring object  20  and photo-curable adhesive module  50  to abut mounting surface  60 . Then, a hand-held chemiluminescent light source  30  will be activated by twisting, bending, flexing, crushing, etc., and the diver will bring it near, or adjacent to photo-curable adhesive module  50  and cure it with light radiated from source  30 . 
     The particular chemiluminescent light source  30  chosen may be any of several sources available in the art. Such chemiluminescent light sources might have two or more different chemical compounds, usually in solution or slurry-like solution, separated by membrane  31 . When membrane  31  is ruptured and the different chemical compounds of chemiluminescent light source  30  come together, they produce light via chemically induced fluorescence or phosphorescence processes. Additional mixing of some of the chemical compounds may be desirable to get more acceptable chemical light production, and, consequently, repeating the actuation of push button  13  and further injecting, twisting, bending, flexing, crushing, shaking, or other agitation may be needed to arrive at useful levels of intensity of radiated light. This further mixing of chemiluminescent light source  30  of bonding system  10  might be done before or after photo-curable adhesive  50  is placed against surface  60 . Irrespective of how much mixing of the chemical compounds is needed, the reaction produces an excited chemical state from which light is emitted to cure photo-curable adhesive  50 . 
     Different chemiluminescent chemical compounds in chemiluminescent light sources  30  cause emissions at different wavelengths of light. Thus, chemical compounds may be chosen to emit the wavelengths of light which initiate and produce cure in selected photo-curable adhesives  50  in accordance with this invention. By way of examples, some typical chemiluminescent light sources that may be selected are the chemical light products marketed by Omniglow Corporation, 96 Windsor St., West Springfield, Mass. 01059 under the trademarks CHEMLIGHT, CYALUME, SNAPLIGHT, and PML. These products include personnel marker lights, lightsticks, S.O.S., green-and-orange signals, and light circles. World Plastics Corporation, P.O. Box 14873, Cincinnati, Ohio 45250 also markets chemiluminescent products under the trademarks BRITEROPE and BRITESTICKS. The products themselves or compounds in these products can be selected to function in chemiluminescent source  30 . In addition, other light emitting chemicals could be selected for chemiluminescent light source  30 , such as the reagents employed for H 2 O 2 /oxalate reactions, peroxyoxalate chemiluminescence, polymer based oxalate sources, oxalate-fluorophore coupled compounds, etc. Various compounds will emit at different wavelengths, and, therefore, an acceptable compound may be selected to initiate and maintain curing of selected photo-curable adhesive  50 . 
     Bonding system  10  may have membrane-like barrier  40  to assure that chemicals of chemiluminescent light source  30  and photo-curable adhesive  50  are physically separated from each another. Barrier  40  also allows appropriate wavelengths of light to pass to initiate curing of photo-curable adhesive  50 . Thus, barrier  40  can be made from chemically non-reactive materials, such as some plastics which are transparent, translucent, or light filtering to pass the curing wavelengths of light from chemiluminescent light source  30  to photo-curable adhesive  50 . 
     Photo-curable adhesive  50  can be an epoxy, methacrylate, or any type of photo-curable adhesive as long as it is tuned to the radiation of the selected chemiluminescent light source  30 . Photo-curable methacrylate adhesives can be tuned to respond to different wavelengths of light depending on the photo initiator compound added to it, and photo-curable epoxies can be tuned to respond similarly may be used. Light curable composite resins, such as marketed under the trademark HELIOMOLAR by Vivavenet, might be used as adhesive  50  when visible light is emitted from chemiluminescent light source  30 . Another photo-curable methacrylate resin is comprised of 50% BisGlycidal Methacrylate (BisGMA) and 50% Triethylene Glycol dimethacrylate with traces of camphorquinone and aminoalkyl methacrylate. This resin can be filled with both strontium glass or silica. 
     Some other typical formulations for photo-curable adhesive  50  for underwater light curing applications are: 
     
       
         
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                 Poly 
                   
                   
                   
                   
                   
                   
                   
               
               
                   
                 PC 
                 BD 
                   
                 SB 
                 PBD 
                 Fumed 
               
               
                 Lot 
                 1000 
                 605 
                 ENC 
                 Diblock 
                 Diol 
                 Silica 
                 CHVE 
                 DVE 
                 Zonarac 
               
               
                   
               
             
             
               
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                 65 
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                 3 
                 60 
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                 4 
                 70 
                 . 
                 25 
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                 5 
                 65 
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                 05 
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                 80 
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                 15 
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     (All amounts are given in parts per weight; each lot of the formulations contained 3 wt % coupling agent and 2 wt % triethylene glycol except for vinyl ether formulations, and 5 wt % IOC8 photo initiator. And the listed chemicals: PC 1000 is a cycloaliphatic silicone diepoxide resin supplied by Polyset Co., P.O. Box III, Mechanicville, N.Y. 12118; IOC8 is (4-octyloxyphenyl)phenyliodonium hexafluoroantimonate supplied by General Electric Silicones, 260 Hudson River Rd., Waterford, N.Y. 12188; Poly BD 605 is an epoxidized elastomer, PBD Diol is polybutadiene diol, and SB is styrene-butadiene block polymer supplied by Shell Chemical Co., Houston, Tex.; ENR is Epoxidized natural rubber supplied by W. Symington &amp; Son, Ltd. Bath House, 53/60 Holborn Viaduct, London ECIA 2ES,UK; Fume Silica is Aerosil R-812 supplied by Degussaf Inc., 2 Pennsylvania Plaza, New York, N.Y. 10001; CHVG is 1,4-cyclohexylmethyldivinyl and DVE is diethylene glycol divinyl ether both supplied by International Specialty Products, 1361 Alps Road, Wayne N.J. 07470-3688; triethylene glycol is supplied by Aldrich Chemical Co., P.O. Box 355, Milwaukee, Wis. 53201; coupling agent (A-187) is 2(3epoxycyclohexylethyl)trimethoxysilane supplied by Union Carbide Corp., 39 Old Rigebury Rd., Danbury, Conn. 06817-0001 or Gelest, Inc., 612 William Leigh Dr., Tullytown, Pa. 19007-6308; and Zonatac is a terpene resin supplied by Arizona Chemical Co., 1001 E. Business Highway 98, Panama City, Fla. 32901). 
     Whatever compound is selected for photo-curable adhesive  50 , removable cap  51   a , or protective skin-like covering  51   b  is provided on its outwardly facing surface  52 . When bonding system  10  is to be attached, cap  51   a , or covering  51   b  is removed to expose surface  52  just prior to placing it on mounting surface  60 . Optionally, some uses of this inventive concept may call for photo-curable adhesive  50  being injected or dispensed onto mounting surface  60 , e.g., to repair a surface or to mount object  20  onto surface  60  directly. 
     In operation, system  10  may adhesively attach object  20  to surface, or substrate  60  in different environments, including submerged locations. Object  20  is placed next to mounting surface  60 . Next, cap  51   a  or covering  51   b  is removed from photo-curable adhesive  50 . Push button  13  is pushed (or activated) and portion  14  breaks membrane  31  that separates chemiluminescent chemicals of source  30 , see FIG.  2 . 
     As mentioned above, chemiluminescent light source  30  could be separated from object  20 , barrier  40 , and photo-curable adhesive  50 , or only photo-curable adhesive  50  could be joined to object  20 . Chemiluminescent light source  30  could be wrapped around photo-curable adhesive  50 , or hand-held, for example, and could be brought adjacent to radiate light onto photo-curable adhesive  50 . 
     As membrane  31  breaks and, possibly, the chemiluminescent chemicals are further mixed, shaken or otherwise agitated, the chemiluminescent chemicals emit light. Immediately prior to or during this time, exposed, outwardly facing surface  52  is placed against mounting surface  60 . Emitted light continues to pass through transparent barrier  40  to photo-curable adhesive  50 . Photo-curable adhesive  50  begins to cure as its photo initiator is energized by irradiation from chemiluminescent light source  30 . Object  20  is bonded to surface  60  as cure of photo-curable adhesive  50  progresses. Total curing of photo-curable adhesive  50  may not be necessary for object  20  to remain bonded for its needed function (or service). 
     Referring to FIG. 3, bonding system  10  could be strip or layer-shaped modules of chemiluminescent light source  30  and photo-curable adhesive  50 . These modules both could be contained in radiation-transparent envelopes that permit passage of radiation emitted from chemiluminescent light source  30  to photo-curable adhesive  50 , for example. The envelopes themselves could function as barrier  40  as discussed above. Of course, the envelope for photo-curable adhesive  50  would have to have a removable cap  51   a , or protective skin-like covering  51   b  on its outwardly facing surface  52  to expose adhesive for bonding onto a surface. 
     The modules of chemiluminescent light source  30  and photo-curable adhesive  50  of FIG. 3 could be joined together (glued, tied, extruded in adjoining, elongate or bag-like, radiation-transparent containers, etc.). These modules of chemiluminescent light source  30  and photo-curable adhesive  50  also might be separated from one another in differently-shaped, radiation-transparent envelopes, and when bonding photo-curable adhesive  50 , these separated modules could be brought in close proximity to emit chemiluminescent radiation from chemiluminescent light source  30  onto photo-curable adhesive  50 . Either of these joined-together or separated structures can have a variety of configurations, such as coextensive rod-like, planar, concentric, or coiled arrangements of modules of chemiluminescent light sources  30  and photo-curable adhesives  50 , depending on the use that is to be made of them. These joined-together or separated structures, can be made to remove chemiluminescent light source module  50  from photo-curable adhesive module  30  after photo-curable adhesive module  30  has cured and the desired bonding has been effected. Furthermore, in all embodiments of this inventive concept, it is an option to have parts of the chemical compounds used for generation of chemiluminescent light and parts of the chemical compounds used to function as a photo-curable adhesive to be mixed together. This may be done so long as they are compatible and do not interfere with each other&#39;s function and operation. 
     The disclosed components and their arrangements as disclosed herein all contribute to the novel features of this invention. These novel features assure more reliable and effective initiation and curing of photo-curable adhesive  50  and bonding of object  20  onto bonding surface  60  and may be differently shaped. Surface  60  could be differently contoured in nearly any shape; however, essential components of bonding system  10  also need to be similarly shaped to contiguously accommodate such a surface. This would not present much difficulty, however, since pliant photo-curable adhesive  50  usually can be easily molded. Tailoring these components for these different surfaces is well within the scope of this inventive concept. Furthermore, having this disclosure in mind, one skilled in the art to which this invention pertains will select and assemble components for bonding system  10  from among a wide variety available in the art and appropriately interconnect them to satisfactorily function as the disclosed invention which relies on different chemiluminescent light sources  30  emitting different wavelengths of light to cure different photo-curable adhesives  50 . Therefore, the disclosed arrangement is not to be construed as limiting, but rather, is intended to be demonstrative of this inventive concept. 
     In accordance with this invention bonding system  10  is an inexpensive and expendable photo-curable adhesive system, and designs utilizing this system are greatly simplified over electrically powered systems. Bonding system  10  may be used where it is not expedient to use radiation from electric lamps or other sources of electrically generated radiation. System  10  does not require any electrical energy (conventional electrical power or batteries) and ancillary equipment to initiate and/or produce curing in photo-curable adhesive  50  and bonding to surface  60 . Consequently, logistical support for curing photo-curable adhesive  50  is greatly reduced or eliminated. 
     It should be readily understood that many modifications and variations of the present invention are possible within the purview of the claimed invention. It is to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.