MXPA01003504A - Optical fiber connector using colored photocurable adhesive - Google Patents

Abstract

A colored adhesive useful for an optical fiber connection or termination, containing an adhesive component having a viscosity between about 200 centipoise and about 5000 centipoise, a colorant which is soluble in the adhesive component having a first color before exposure to radiation having a wavelength of from about 400 to about 1100 nanometers, and a second color after exposure to radiation, and an initiator system to cure the adhesive composition by exposure to the radiation.

Description

OPTICAL FIBER CONNECTOR USING PHOTOCURABLE COLORED ADHESIVE Background of the Invention Field of the Invention The invention relates to an adhesive composition for attaching an optical fiber to a suitable housing using light, in the ranges of the visible and near infrared spectrum, to cure the adhesive. A colorant included in the adhesive composition provides evidence that the space between the optical fiber and the housing is filled prior to curing. The dye also indicates the point at which exposure to a light source is sufficient to cure the adhesive and bond the optical fiber within the housing. Description of the Prior Art The successful use of fiber optic cables for the conduction, for example, of telecommunication signals, depends on maintaining the axial alignment of the fiber along the length of the cable although it can be subjected to clamped fastenings jointly by suitable termination structures or connectors. The correct placement of the optical fiber, within the termination structure or connector, represents a REF: 128508 critical requirement to maintain maximum signal transmission through a precision aligned fiber splice. The precise alignment depends on the retention of a fixed spatial relationship between the fiber and the connector structure. When the correct spatial relationship, exactly established, ensures the desired fiber-to-fiber alignment during splice formation using the termination structures or interconnect connectors, which can be subjected to repeated coupling and uncoupling. A convenient means of establishing the correct spatial relationship between an optical fiber and a connector involves the use of a connecting or bonding material, usually an adhesive, to secure the fiber to an inner surface of the connector structure. There are many examples of the use of adhesives, of various kinds, for connecting or splicing optical fibers within the connector structures. U.S. Patent No. 4,588,256 discloses the use of hot melt adhesive, contained in an optical fiber mounting means, within a connector. After heating the mounting means of the optical fiber, the hot melt adhesive softens, allowing the insertion of the optical fiber which becomes attached to the mounting means when the adhesive cools and solidifies. Similarly, U.S. Patent Nos. 4,984,865 and 5,048,915 use thermoplastic adhesives to bond an optical fiber within a connector structure. In both cases, a small amount of molten adhesive is exuded from the tip of the connector under the force of insertion of the optical fiber to the hot thermoplastic adhesive. After cooling, a small drop of adhesive surrounds or surrounds the fiberglass at the tip or end of the connector. This formation of the drop, although it suggests that the adhesive surrounds the optical fiber, does not provide confirmation that the adhesive fills the connector. The filling of the connector, places the adhesive in the space between the optical fiber and the inner wall of the connector, provides the optimal condition to securely join the fiber to the connector. Less than the optimal joint could lead to the alteration in the position of the fiber in relation to the connector with loss resulting from the alignment between the fibers present in the connectors used to splice lengths of optical cable together. A means for indicating the optimal connection between the optical fibers and the connection structures could be advantageous for providing reliable fiber optic connections. Suitable means of indication could confirm that the bonding or binding formation is capable of surviving forces associated with the shock or discharging or extension of a connection. The present invention provides a means for indicating optimal bond formation using a colored adhesive composition, which, during bonding of the optical fiber within a fiber connector structure, exhibits uniform coloration when the adhesive fills the space between the fiber and the connector in a first color. The adhesive is cured by exposure to visible light, and when it is cured, the first color changes to a second color at the start of curing. Furthermore, such an adhesive could be of a small viscosity so that it is injectable, however, sufficiently large, so that when it is injected it remains in the desired area of the connector and does not migrate to other areas. Brief Description of the Invention The invention provides an adhesive which bonds an optical fiber to a fiber housing in a fiber optic connector. The adhesive contains a dye to show that the space between the optical fiber and the housing is filled prior to the curing of the adhesive with light of wavelengths found in the visible and near-infrared range of the spectrum. When the adhesive cures, the dye also signals the sufficient exposure point to the light to join the optical fiber inside the housing. More specifically, the invention provides a composition for curing and distributing the adhesive for an optical fiber connection or termination, comprising: an adhesive having a viscosity from about 200 centipoise to about 5000 centipoise, a dye, which is soluble in the adhesive to show how the adhesive is distributed within the connection or termination, the dye having a first coloration before exposure to radiation from about 400 to about 1100 nanometers, but preferably from approximately 400 to about 700 nanometers, and a second color after exposure, and an indicator system for curing the adhesive composition by exposure to such radiation, the composition preferably has a cure beginning from about 60 seconds with the formation of the second color, more preferably up to about 30 seconds.

Preferably, the adhesive component comprises at least one acrylate monomer. The adhesive is curable by light of wavelengths from about 400 to about 1100 nanometers, preferably from about 400 to about 700 nanometers, more preferably from about 400 to about 600 nanometers, including a portion of the blue and green area of the spectrum, more preferably between approximately 500 and approximately 600 nanometers. The adhesive composition is cured and the colorant changes color in less than 30 seconds, preferably less than about 25 seconds, more preferably in less than about 15 seconds. The adhesive binds strongly to the fiber optic and fiber optic connector housing. . The invention also provides a method for attaching an optical fiber to a connector. As used herein, these terms have the following meanings. 1. The term "visible light" means electromagnetic radiation having wavelengths between about 400 nm and about 700 nm. 2. The term "near infrared", abbreviated "nIR", means electromagnetic radiation having wavelengths between about 700 nm and about 1000 nm in form. 3. The term "retaining device" generally refers to the portion of an optical connector designed to secure an optical fiber within the connector or termination. 4. The term "connector" means an article for aligning a first optical fiber with a second optical fiber establishing contact between the ends of the fiber and thereafter a means of lodging is included to retain the extreme contact of the fiber and the alignment of fiber. 5. The terms "connection" and "termination" mean the point at which the end of a first optical fiber is kept in contact with the end of a second optical fiber. The terms "connector", "connection", and termination are used interchangeably. 6. The term "(meth) acrylate" includes both acrylate and methacrylate. 7. The terms "epoxy" and "epoxide" mean an organic resin having at least one oxirane ring which is polymerizable by the opening of the ring. 8. The term "epoxy acrylate" means a material that contains both an epoxide functionality and an acrylate functionality in the same molecule, or a mixture that contains both acrylate and epoxy functionally in separate molecules. 9. The terms "coloring" and "color component" are synonyms and mean a compound which has a visible color. As used herein, all parts, percentages, and proportions are by weight, unless specifically stated otherwise. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reference to the appended drawings, wherein: Figure 1 is a side view of a longitudinal section of an embodiment of the present invention, showing a fiber optic connector including a plug or plug and receptacle; Figure 2 is a perspective view of the plug or plug and receptacle of Figure 1, with a partial section that discovers the fibers inclined inside the plug or pin. Figure 3 is a cross section of an alternative connector. Detailed Description of the Invention The optical fiber assemblies of the invention comprise at least one optical fiber in a retention device, adhered to the retention device by means of a colored photocurable adhesive, this adhesive changes color when it is exposed to radiation in the appropriate portion of the spectrum. The color change indicates the beginning of curing, ie, the adhesive has been exposed to sufficient radiation to be polymerized; The color can be inspected for uniformity to help in the evaluation of the level of curing of the adhesive. The color change could be within approximately sixty (60) seconds, preferably within about 30 seconds, more preferably within about 25 seconds, more preferably within about 15 seconds. Useful adhesives comprise an adhesive component, a free radical initiator system, and a colorant, which can be separated or can be a portion of the initiator system. The adhesive components useful in the optical fiber compositions and assemblies of the invention have a viscosity of about 200 to about 5000 centipoise (cps), preferably from about 400 to about 4000 cps, most preferably from about 400 to about 400 cps. approximately 3000 cps. Adhesive components useful in the system include those formed from at least one epoxy resin, those containing at least one (meth) acrylate monomer, and those formed from at least one epoxy resin and at least one (meth) monomer Acrylate Useful (meth) acrylate monomers include mono-, di- or poly (meth) acrylates such as methyl acrylate, methyl methacrylate, ethyl (meth) acrylate, (meth) isopropyl acrylate, allyl (meth) acrylate, glycerol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene di (meth) acrylate, triethylene glycol di (meth) acrylate, di (meth) 1,3-propanediol acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, sorbitol hexacylate, tri (iaet) trihydroxyethyl isocyanurate acrylate, bis- (meth) acrylate of polyethylene glycols having molecular weights of up to about 500, copolymerizable mixtures of acrylate monomers, for example those described in U.S. Patent 4,642,126, incorporated herein by reference, and the like. Other radically free polymerizable monomers, ie, ethylenically unsaturated compounds such as vinyl ethers, diallyl phthalate, styrene, and the like, may also be used in adhesive compositions therein. Useful epoxy materials include linear polymers having terminal epoxy groups, polymers having oxirane units of the backbone and polymers having pendant epoxy groups such as glycidyl ether monomers having the formula RTOCH? -CH-CB,) V n wherein R 'is alkyl or aryl and n is an integer having a value of 1 to about 6. Examples are glycidyl ethers of phenols. polyhydric obtained by reacting a polyhydric phenol with an excess of chlorohydrin. This type of epoxide is described extensively in U.S. Patent No. 3,018,262, incorporated herein by reference. Commercially available epoxy resins useful herein include Bisphenol A glycidyl ether, for example, those available as "Epon 828", "Epon 8225", "Epon 1004", and "Epon 1010" from Shell Chemical Co., and those available as "DER-331", "DER-332", and "DER-334" from Dow Chemical Co., vinylcyclohexene dioxides including "ERL-4206" from Union Carbide Corp .; 3,4-epoxycyclohexylmethyl-3, -epoxycyclohexene carboxylates such as "ERL-4221", "Cyracure UVR 6110", or "UVR 6105" from Union Carbide Company, 3,4-epoxy-6-methylcyclohexylmethyl-3 carboxylate, 4-epoxy-6-methyl-cyclohexene such as "ERL-4201" from Union Carbide Corp., silicone resins containing epoxy functionalities, and the like. Also useful are alkyl glycidyl ethers, epoxies available under the trademark "HELOXY Modifier" from Shell Chemical Company, epoxides of bisphenol F, available from "EPN-111138" or "GY-281" from Ciba Specialty Chemical Corp., and , 9-bis [4- (2, 3-epoxypropoxy) -phenyl] fluoroenone, available as "Epon 1079" from Shell Chemical Company. The epoxy resin polymers may contain other functionalities as long as the added functionality does not interfere substantially with the cationic curing at room temperature. Epoxy resin blends are also useful. Polyols useful for polymerizing the epoxy resins include monomeric polyhydroxy materials including alkylene glycols such as 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,8-octanediol, 2-ethyl-1,6-hexanediol.; bis (hydroxymethyl) cydohexane; polyhydroxyalkanes such as glycerin, tri-methylolethane, pentaerythritol, sorbitol, N, N-bis (hydroxyalkyl) benzamide; 1-butyn-l, 4-diol, 4, 4-bis (hydroxymethyl) diphenylsulfone, castor oil, and the like. Useful polymer polyols include polyoxyethylene and polyoxypropylene glycols, particularly those having molecular weights from about 200 to about 10,000, polytetra ether ethylene ether glycols such as polytetrahydrofuran or "polyTHF" compounds of varying molecular weight, hydroxypropyl and hydroxyethyl (meth) copolymers ) acrylates, copolymers containing the pendant hydroxy group formed by hydrolysis or partial hydrolysis of vinyl acetate copolymers, polyvinylacetal resins containing pendant hydroxyl groups; modified celluloses such as hydroxyethylated and hydroxypropylated celluloses; polyesters terminated with hydroxy, polyalkadienes and polylactones, particularly polycaprolactones, fluorinated polyoxyethylene and polyoxypropylene glycols. Commercially available, useful hydroxyl-containing materials include polytetramethylene ether glycols such as "TERATHANE" 650, 1000, 2000 and 2900 (available from du Pont de Nemours, Wilmington, DE); polyoxyalkylene tetroles having secondary hydroxyl groups such as "PEP" 450, 550 and 650; polyvinylacetal resins such as "BUTVAR" B-72a, B-73, and semejants (available from Monsanto Chemical Company, St. Louis, MO); resins such as "FORMVAR" 7/70, 12/85, 7 / 95S, and the like (available from Monsanto Chemical Company); polycaprolactone polyols such as "TONE" 0200, 0210, 0300, and the like (available from Union Carbide); polyester-aliphatic diol such as "PARAPLEX U-148" (available from Rohm and Haas, Philadelphia, PA); saturated polyester polyols such as the "MULTRON" R series from Mobay Chemical Co .; hydroxypropylated cellulose having an equivalent weight of about 100, such as "KLUCEL E" from Hercules Inc .; cellulose acetate butyrate ester "Alcohol Soluble Butyrate" having a hydroxyl equivalent weight of about 400 (available from Eastman Kodak Co., Rochester, NY); polyether polyols such as polypropylene glycol diol (for example, the "ARCOL PPG" series from ARCO Chemical Co.); polypropylene glycol triol such as "ARCOL" LT-28, LHT-42, LHT-112, and the like (available from ARCO Chemical Co.); triol or polyoxypropylene diol topped with ethylene oxide such as "ARCOL" 11-27, 11-34, E-351, E-452, and the like, from ARCO Chemical Co .; bisphenol A ethoxylate; polyols based on ethylene oxide or propylene oxide such as polyether polyols "VORANOL" from Dow Chemical Co. The adhesive component can also contain polymerizable functionalities both free of co or epoxy radicals, in a single molecule. These can be obtained by reacting a di or polyepoxide with one or more equivalents of an ethylenically unsaturated carboxylic acid. An example is the reaction product of UVR-6105 with an equivalent of methacrylic acid or acrylic acid. Commercially available materials having radically free and expoxy polymerizable functionalities include the "Cyclomer" series available from Daicel Chemical. The photoinitiator system is one that is capable of absorbing light in the visible range, that is, between approximately 400 nm and approximately 700 nm. In preferred embodiments of the invention, the photoinitiator absorbs light between about 400 nm and about 600 nm, most preferably between 500 nm to about 600 nm, in the green and a portion of the blue portion of the spectrum. The components in the photoinitiator system include at least one initiator and, preferably, at least one sensitizer. These initiator systems initiate the polymerization of both the epoxy resin and the free radical monomers when sufficient radiation of suitable wavelengths is absorbed. Useful sensitizers should be soluble in the monomer and are capable of absorbing light at the appropriate wavelengths. The sensitizer, preferably, is also capable of sensitizing 2-methyl-4,5-bis (trichloromethyl) -s-triazine, in accordance with the test procedure described in US Patent No. 3,729,313, incorporated herein by reference. Preferably, the sensitizer is also freestanding for reasonable periods of time. It is believed that suitable sensitizers include compounds in the following categories: ketones, coumarin dyes (e.g., keto-coumarins), xanthan dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes , aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons, p-substituted aminostyryl ketone compounds, aminotriaryl methanes, merocyanines, escuiarilium dyes and pyridinium dyes. Ketones (for example, monoketones or alfadicetones), ketocoumarins, aminoaryl ketones and p-substituted aminostyryl ketone compounds, sensitizers are preferred. For applications requiring high sensitivity, it is preferred to employ a sensitizer containing a julolidinyl moiety. For applications that require depth curing (for example, where the reinforcing coating or fibers attenuate radiation of similar wavelengths), it is preferred to employ sensitizers having an extinction coefficient of less than about 1000, more preferably less than about 100, at the desired wavelength of irradiation for photopolymerization. Alternatively, sensitizers that exhibit discoloration or bleaching at the appropriate wavelength (s) may also be used. In this reaction, the sensitizer discolours the composition, and the initiation can then progress through the layer or layers of material. By way of example, a preferred class of ketone sensitizers has the formula ACO (X) bB wherein X is CO or CRXR2, wherein R1 and R2 may be the same or different, and may be hydrogen, alkyl, alkaryl or aralkyl , b is one or zero, and A and B can be the same or different and can be substituted (by having one or more substituents that do not interfere) or unsubstituted alkyl, alkaryl, aralkyl or aryl groups, or together A and B can form a cyclic structure which can be a fused, aromatic heteroaromatic or substituted cycloaliphatic or unsubstituted aromatic ring. Suitable ketones of the above formula include mono-ketones (b = 0) such as 2,2-, 4,4- or 2,4-dihydroxybenzophenone, di-2-pyridyl ketone, di-2-furanyl ketone, di-2. -thiophenyl ketone, benzoin, fluorenones, quinones, for example, chloroquinone, 2-aza-3-carboxy-9-fluorenone, and the like, chalcone, Michler's ketone, 2-fluoro-9-fluorenone, 2-chlorothioxanthone, acetophenone, benzophenone, 1- or 2-acetonaphthone, 9-acetylanthracene, 2-, 3-or 9-acetylphenanthrene, 4-acetylbiphenyl, pripiophenone, n-butyrophenone, valerophenone, 2-, 3- or 4-acetylpyridine, 3-acetylcoumarin and the like . Suitable diketones include aralkyldicyketones such as anthraquinone, phenanthrenquinone, o-, m- and p-diacetylbenzene, 1,3-, 1,4-, 1,5-, 1,6-, 1,7- and 1,8- diacetylnaphthalene, 1,5-, 1,8- and 9,10-diacetylanthracene, and the like. Suitable a-diketones (b = 1 and X = CO) include 2,3-butanedione, 2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione, 3,4- heptanedione, 2,3-octanedione, 4,5-octanedione, benzyl, 2,2'-, 3,3'- and 4,4'-dihydroxylbenzyl, furyl, di-3,3'-indolylenedione, 2, 3- bornanedione (camphorquinone), 1,2-cyclohexanedione, 1,2-naphthaquinone, acenaphthaquinone, and the like. At least one sensitizer must be present in this photoinitiator system which absorbs visible light. Surprisingly, this dye 1) identifies the location of the adhesive in the connector, 2) participates in the curing reaction; and 3) undergoes a color change which reflects the start of curing. Other preferred sensitizers include Rose Bengal, Methylene Violet, Fluorescein, Eosin Yellow, Eosin Y, Ethyl Eosin, Eosin Bluish, Erythrosin Yellowish Blend, 4A 5 '-Dibromofluorescein.

Typically the photoinitiator system also includes an electron donor, although this is not required. A wide variety of donors can be used, the donor must be soluble in the monomer, and have good self-stability. Suitable donors are capable of increasing the curing speed or curing intensity of a composition upon exposure to light of the desired wavelength. The donor has an oxidation potential greater than zero, and less than or equal to the oxidation potential of p-dimethoxybenzene. Preferably the potential oxidation is between approximately 0.5 and 1 volts vs. a calomel electrode or saturated mercury chloride (S.C.E.). The values can be measured experimentally or can be obtained from references such as N.L. Weinburg, Ed., Technique of Electroorganic Synthesis Part II Techniques of Chemistry, Vol. V (1975) and the like. Preferred donors include amines (including aminoaldehydes and aminosilanes), amides (including phosphoramides), ethers (including thioethers), ureas (including thioureas), ferrocene, sulfinic acids and their salts, ferrocyanide salts, ascorbic acid and its salts, dithiocarbamic acid and its salts, salts of xanthates, salts of ethylene diamine tetraacetic acid, and salts of tetraphenylboronic acid. The donor may be substituted or unsubstituted with one or more substituents without interference. Particularly preferred donors contain an electron donating atom such as a nitrogen, oxygen, phosphorus, or sulfur atom, and a hydrogen atom that can be extracted by distillation attached to a carbon or silicon alpha atom to the electron donating atom. Preferred amine donor compounds include alkyl-, aryl-, alkaryl- and aralkyl-amines such as methylamine, ethylamine, propylamine, butylamine, triethanolamine, amylamine, hexylamine, 2,4-dimethylaniline, 2,3-dimethylaniline, or- , m- and p-toluidine, benzylamine, aminopyridine, N, N'-dimethylethylenediamine, N, N'-diethylethylenediamine, N, N'-dibenzylethylenediamine, N, N'-diethyl-1,3-propanediamine, N, N ' -diethyl-2-buten-1, 4-diamine, N, N'-dimethyl-1,6-hexandiamine, piperazine, 4,4'-trimethylenedipiperidine, 4,4'-ethylenedipiperidine, pN, N-dimethyl-aminophenol and pN, N-dimethylaminobenzonitrile; aminoaldehydes such as p-N, N-dimethylaminobenzaldehyde, p-N, N-diethylaminobenzaldehyde, carboxaldehyde of 9-julolidine and 4-morpholinobenzaldehyde; and aminosilanes such as trimethylsilylmorpholine, trimethylsilylpiperidine, bis (dimethylamino) diphenylsilane, tris (dimethylamino) methylsilane, N, N-diethylaminotrimethylsilane, tris (dimethylamino) phenylsilane, tris (methylsilyl) amine, tris (dimethylsilyl) amine, bis (dimethylsilyl) amine, N, N-bis (dimethylsilyl) aniline, N-phenyl-N-dimethylsilylaniline, and N, N-dimethyl-N-dimethylsilylamine. Tertiary aromatic alkylamines, particularly those having at least one group that removes electrons on the aromatic ring, have been found to provide especially good self-stability. Good self-stability has also been obtained using amines that are solid at room temperature. Preferred amide donor compounds include N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-N-phenylacetamide, hexamethylphosphoramide, hexaethylphosphoramide, hexapropylphosphoramide, trimorpholinophosphine oxide, and tripiperidinophosphine oxide. Suitable ether donor compounds include 4,4'-dimethoxybiphenyl, 1,2,4-trimethoxybenzene and 1,2,4,5-tetramethoxybenzene. Suitable urea donor compounds include N, N'-dimethylurea, N, N-dimethylurea, N ', N' -diphenylurea, tetramethylthiourea, tetraethyl thiourea, tetra-n-butyl thiourea, N, N-di-n-butyl thiourea, N, N '-di-n-butylthiourea, N, N-diphenylthiourea and N, N' -diphenyl-N, N '-diethylthiourea. In one embodiment of the invention, the photoinitiator system is a ternary system, according to U.S. Patent No. 5,545,676, incorporated herein by reference. In a three component system, the additional component is a diaryliodonium salt. The iodonium salt should also be soluble in the monomer and will be freestanding when dissolved therein in the presence of the sensitizer and donor. Accordingly, an election of a particular iodonium salt may depend to some degree on the selected monomers, and the other portions of the photoinitiator system. The ternary system must contain these three parts, however, it may contain more than one sensitizer or electron donor, if desired. . Useful salts are those described in U.S. Patent Nos. 3,729,313, 3,741,769, 3,808,006, 4,250,053 and 4,394,403, the iodonium salt portions of the descriptions of which are incorporated herein by reference. Preferred iodonium salts include diphenyliodonium chloride, diphenyliodonium hexafluorophosphate and diphenyliodonium tetrafluoroborate.

The adhesives of the invention are prepared by mixing, under conditions of "high safety", the components of the composition. The solvents can be used if desired, an inert solvent can be used. Examples of suitable solvents include acetone, dichloromethane, and acetonitrile. A monomer to be polymerized as a solvent may be used for another material to be polymerized. Compositions without solvent can also be prepared, with or without the use of light heating to facilitate dissolution. If desired, fillers can be added to the extent that they do not interfere with the polymerization process. Useful fillers include silica, pigments, antioxidants, glass materials, and the like. . The adhesive of the present invention can be used with a variety of different connector designs. Figures 1 and 2 illustrate an embodiment 10 of an optical fiber connector according to the present invention. The connector 10 is comprised of an elongated plug 12 and a receptacle or receptacle 1. Figure 1 is a longitudinal section of the connector 10 showing the plug or plug 12 fully inserted into the receptacle 14, and receptacle 14 mounted on a support surface or sealing piece 16. Figure 2 is a perspective view with a part 16 also omitted with a partial longitudinal section to illustrate the inside of the connector. The embodiment shown provides the interconnection of two fiber pairs, but those skilled in the art will appreciate that the concepts of the invention described herein extend to the single-pair interconnection as well as the interconnection of a multiplicity of pairs. The cap or plug 12 includes a retainer 18 of the fiber, which can be constructed of two securing elements or blocks 20 and 22, and a plug body or reinforcing ring 24 which is attached to the retainer the fiber 18. The optical fibers 30 and 32 which are to be interconnected or terminated passed through the retainer 18 and into the hollow interior of the reinforcing ring 24. The end portions of the fibers are uncoated, i.e. they are not fixed to any alignment member such as a splint or splice sleeve. Therefore, the reinforcing ring 24 serves not only to assist in physically locating the plug 12 in the receptacle 14, but also provides protection for the otherwise exposed end portions of the fibers (the reinforcing ring could be made in retractable form to fully expose the ends of the fiber if required). The holding device 18 has fiber receiving notches 34 formed in the adjacent surfaces of the blocks 20 and 22; These two components can be identical parts. The optical fibers are secured to the retaining device 18 by the use of the adhesive described above. The adhesive is injected through the cavities in the connector for this purpose, and is cured. The adhesive must adhere to the cable jacket. Which is typically epoxy silicone, polyolefin or polyvinyl chloride, where it is still present as well as reinforcing fibers, eg, Kevlar®, in those. areas where the outer coating has been removed or removed, and finally the fiber itself to keep the fiber in position. The retaining device 18 may have an extension 36 surrounding the fibers to release the additional tension and securing. A cover or sheath 38 can be provided to release the additional tension and capture the reinforced fibers in the fiber cable (strands or KEVLAR® cords), and assist in the handling of the plug 12. The reinforcing fibers do not need to be bent or finished, but they can be adhered to the unified structure of the retention device by means of the same adhesive as used to secure the fiber to the retention device, as described above. The tension relief of the reinforcing elements is achieved by an adjusted force of the straight wall section of the fiber optic retaining device within the cover 38. This is dependent on the choice of materials used for the cover or sheath 38 and the fiber optic retention device 18, and produce a design that does not require a securing ring and which aids easy fabrication and reduces the number of components needed. "A way" of removing peaks on the surface of the fiber optic retention device assists in attaching the cover or cover 38 to the retention device of the optical fiber 18, which also assists in the fastening of the cable to the cap 12 A retainer or retainer 40 is integrally molded on one side of the reinforcing ring 24 to releasably secure the cap 12 to the receptacle 14. The retainer or retainer circuit 40 can also impart mechanical polymerization to the cap, i.e. it can insert into the receptacle 14 only in one orientation. The plug 12 can be biased in the interconnected position, for example, by a trampoline (a flexible bracket) formed within the receptacle 14, to be pushed back against the retainer or retainer circuit 40 to minimize the effect of manufacturing tolerances. The receptacle 14 includes a body or housing 70 and another fiber retention device 72. The housing 70 may also have appropriate features (such as clamping arms 76) that allow it to be releasably mounted to the sealing part 16 of the housing. which can be, for example, a control panel or output from the work station (front plate of the box, of the wall). The clamping mechanism can be provided for mounting from the front of the panel, to allow all preparatory work to be given on the front side of the panel, or it can provide mounting from the back of the panel, to allow all the preparatory work done on the back side of the panel. Additional mechanisms, such as fastening of fibers, can be provided to retain the fibers firmly in the notches. The fibers do not extend to the ends of the spacer pieces 82 and 84 but it is preferred to terminate a sufficient distance from the ends to allow proper support of the portion of the optical fibers in the stopper when the connector is in use. If the fiber to fiber contact occurs very close to the ends of the notches V (or if the plug is inserted too far), the fiber portion in the plug can be bent beyond the notches and rise away from the top or vertex, breaking the connection. The receptacle 14 can have as many of these spacer pieces with fiber alignment notches as there are fibers in the cap or pin 12. The spacer pieces 82 and 84 are shaped to project into the slots 54 and 56, respectively, of the cover 24 when the cap 12 is fully inserted into receptacle 14. Spacer pieces 82 and 84 enter cladding 24 at an oblique angle (not zero) with respect to the plug axis, i.e., the axis defined by any of the optical fibers 30 or 32 when they extend straight into the liner 24. This angle is preferably approximately 42 °, this balance refers to the contact pressure of the end face of the fiber, the fiber forces directed in the notch V, the friction effects, and the desired tolerance window (a larger angle increases the tolerances). Since the fibers of the receptacle are not directed towards the opening 74, there is no danger of the light escaping damaging the user's eyes. The receptacle fiber retainer 72 is pivotally attached to the housing 70 providing posts on the first end of the retainer 72 which is broken into switches or hooks 88 formed at one end of the housing of the receptacle 70. The retention device 72 is releasably fixed in place using ridges or projections formed on the side of the retainer, which couple the holes 89 in the receptacle housing 70. An alternative design for the receptacle fiber retainer can be used in which the retainer is molded as a single piece with a top surface of the fire or cover plate that can be cut at its base, the base that has the fiber placement notches. All components of the connector 10 (except the sleeve of the plug or plug 38) may be formed of any durable light transmission material, preferably an injection-moldable polymer such as polycarbonate, VALOX (a polyester sold by General Electric), or RADEL (a polyarylsulphone sold by Amoco). The material may include conductive fillers to return the semiconductor components to minimize the triboelectric charge which may induce the final contamination of the fiber, so that the fillers do not attenuate the radiation too much during curing. The sheath 38 is preferably formed of low modulus copolyester elastomers, such as that available from RTP of Winona, Minnesota, under the material number 1559X67420B. The assemblies and the installation of the connector 10 is quite simple. The plug or plug 12 is typically assembled in the factory, although it can easily be assembled in the field. To place the adhesive in the assembly, the adhesive is simply placed in a syringe-like applicator (if desired, the adhesive may be provided in an applicator), over the opening in the retainer and the adhesive is injected to the adhesive. retaining device 18. The adhesive is then cured by placing a light having the wavelength radiation required above the connector for a period of 5 seconds to a few minutes. Useful lights include the Model XL3000, available from 3M, which uses a 75 Watt tungsten source, either unfiltered or filtered to match the sensitivity of the specific initiator system used. It is also understood that the plug 12 or receptacle 14 could be mounted on a mating cable or connection cable with any kind of optical connector at the other end of the fibers. It is recommended that the fibers be used which have a longer duration when exposed to indoor environments, such as the high strength fibers available from Minnesota Mining and Manufacturing Co. Those fibers have a conventional core and coating which is surrounded by a new three-layer construction, as described in U.S. Patent No. 5,381,504, described herein by reference. Those skilled in the art will also appreciate that the connector of the present invention can accommodate discrete optical fibers or multi-fiber ribbons or bands, as well as fibers both single-mode and multimode. The fibers which are pre-determined for either the plug 12 or receptacle 14, should be peeled, divided and cleaned. If the fibers are in the form of a belt or band which is part of a group of bundles of belts in a cable, then a portion of the cable sheath must be removed to reveal the belts or bands. Many cables have several protective layers, and each of these layers must be removed to provide access to the ribbons or bands of the fiber. Similar steps should be followed to remove the protective layers of a cable that has a single or simple discrete fiber. After the fibers have been removed from the protective cable liner, they are peeled off. The peeled fibers are then ready to be divided which can be done using any of the various commercially available fiber blades, such as those shown in U.S. Patent No. 5,024,363. The length of cut to join the fibers to the plug 12 is the distance of the fiber retention device 18 which, in the preferred embodiment, it is approximately 23 mm. For coupling the fibers to the receptacle 14, the cutting length is the distance from the fiber retention device 72 which, in the preferred embodiment, is approximately 15 mm. Once the person skilled in the art is satisfied that each of the fibers has an acceptable end surface, the fibers can be removed from the blade. In addition, the fibers may optionally be provided with an asymmetric treatment, similar to splitting or cutting to impart an angled or tapered end surface, as taught in U.S. Patent No. 5,048,908. For the plug, the fiber preparation can be given after the fiber cable has been threaded through the sheath 38. The final assembly of the plug 12 comprises the simple steps of placing the fibers in the notches V of the retention device 18 and breaking the liner 24 onto the retainer 18. A mounting device can be used to guide the liner 24 onto the fiber retention device to avoid damaging the fibers when they are inserted into the liner. The ends of the fibers should end in the plug approximately 0.5 mm from the end of the liner. The termination of the receptacle 14 is also simple. The fiber retainer 72 engages the housing 70, first by pushing the pivot posts into the switch 88, and then breaking the projections into holes 89. Care must be taken during the placement of the fibers in the notches V and the coupling from the retention device to the receptacle so as not to contaminate the ends or ends of the fiber. The installation of the connector 10 is also simple. The receptacle 14 is optionally mounted to any desired surface by convenient means, such as clamping arms 76 (another construction could be molded into the housing 70 for custom assembly). Several receptacles may also be mounted on a single module, and they may be designated for front and rear loading, or side displacement. After the receptacle 14 is assembled, the connection is completed by simply inserting the cap 12 into the opening 74. The cap 12 is releasable from the receptacle 14 by the retainer or retainer circuit 40. The dimensions of various components of the connector may vary considerably depending on the desired application. The following approximate dimensions are considered exemplary. The plug 12 has a total length of 57 mm, a width of 12 mm, and a thickness of 8 mm, and the fiber retaining device 18 provides securing notches that are 13 mm long. The cap liner 24 extends 25 mm beyond the retainer 18, providing an interior space which is 24 mm long, 10 mm wide and 6 mm high. The opening 74 of the receptacle 14 is 12 mm x 10 mm. Its height and total depth are 38 mm and 36 mm. The retention device 72 of the receptacle fiber is 20 mm long (from the end where the fibers are secured to the tips of the spacer parts 82 and 84), 12 mm wide and 1.5 mm thick. The fiber alignment notches in the spacer pieces 82 and 84 are 11.5 mm long and have a maximum depth of 2 mm which suitably accommodates more conventional optical fibers. The inner angle of the V-grooves should not be so narrow as this will result in excessive friction with the fibers, but also should not be too wide since this would not keep the fibers properly guided. It is believed that an interior angle of 90 ° is a good arrangement. "In an alternate connector shown in Figure 3, the cover or liner 312 is removed at one end of the fiber optic cable 314, together with the fiber liner and 318 to expose the reinforcement fiber 315 and the optical fiber 318 The adhesive 320 of the invention is injected into the interior of the connector recess and fills an interior surface 321 in a ceramic splice sleeve 322. Although the invention has been described with reference to the specific embodiments, this description is not understood to is built in a limiting sense. Various modifications of the described embodiment, as well as alternative embodiments of the invention, will become apparent to persons skilled in the art with reference to the description of the invention. Variations are possible in the plug, receptacle and holding device. For a detailed description of the mechanical construction of a useful connector, see U.S. Patent Nos. 5,381,498 and 5,757,997, and copending U.S.S.N 08 / 801,058, all of which are incorporated herein by reference. For example, although only two pairs of fibers are shown connected in the figures, the connector 10 could accommodate practically any number of fibers (or only a single or single pair). Therefore, it is contemplated that such modifications may be made without departing from the spirit or scope of the present invention as defined in the appended claims.

Bis GMA Glossary Reaction product of diglycidyl ether of Bis Phenol A and 2 equivalents of methacrylic acid. CD 1012 Diaryliodonium salt. Also known as Sarcat, available from Sartomer CPQ Canforquinone DPIPF Diphenyliodonium hexafluorophosphate EDMAB Ethyl-p-dimethylaminobenzoate PTHF 250 Polytetrahydrofuran TEGDMA Triethylene glycol dimethacrylate UVR 6105 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carboxylate Test Methods Keylar® Tension Test Cables were inserted into the plug of Figure 1 without divergence of Kevlar® output. The cover or shirt was placed approximately 0.010 cm behind the rear injection ports. The adhesive was injected by hand using a 3-ce syringe, which ensured that the cavity was completely filled.

Then each plug was cured with two exposures of 5 seconds, one on the top and one on the bottom with the appropriate light sources. Each duplex cable was cut in half and divided up to two separate cables protruding from the plug. For Kevlar® tractions, the plug was placed in a fixation device that was attached to a chattillon scale DFM100. One at a time, the cables consisting of cover, GGP fiber and Kevlar®, were wrapped around a 6.25 cm diameter mandrel and secured in place. They were pulled at a speed of 1.25 cm per minute until it deteriorated. Fiber Tension Test For fiber pulled or tensioned, after the plug was placed in the fastener that was decribed - for the Kevlar® tension test, the cover was separated about 10.16 cm (four inches) from the stopper, exposing the GGP and Kevlar® fiber. The GGP fiber was wrapped around a 6.25 cm mandrel and secured in place. They were pulled at a speed of 1.25 cm per minute until failure.

The Kevlar® was wound around the 6.25 cm mandrel and pulled at a speed of 1.25 cm per minute until failure. Examples Examples 1-2 and Comparative Examples IC and 2C Samples of fiber optic assemblies were made by peeling or removing the outer jacket of the cable, cutting Kevlar® fibers and inserting the optical fiber into a dual termination connector. Before joining the fibers they were cleaned with a lint-free pad which had been moistened with isopropyl alcohol, then the fibers were inserted into the holding device. Then, two drops of an adhesive having a formulation listed in Table 1 were injected into each channel of the fibers in the dual termination fixation device, and the connector was attached by exposing it for 25 seconds to a 3M Model XL, 3000 which Heals the light that has a 75-watt tungsten source from which the blue filter has been removed. The comparison of the results in Table 1 shows that adhesives without a visible light sensitizer and an indicator dye fail to cure when exposed to visible light. Also, the initiator systems in these examples have been optimized for visible light, and as a result, they do not cure efficiently as a result of exposure comparable to UV radiation. However, when exposed to visible light, curing proceeds and the color change of the dye from the initial color to the final color shows the curing process. In addition, the compositions of the invention exhibit increased extraction force, as shown in Table 2. Identical samples of both the adhesives of the invention and the comparative adhesives were also exposed to ultraviolet light that does not cure. The tensile force needed to remove the fiber from the connector is also shown in Table 1. Table 1 (pph) Examples 3-8; Compositions of Adhesives Using Alternative Dyes The identical formulations were mixed except for the dye selection, to form an adhesive; the various compositions appear in Table 2. The fiber optic assembly was formed as described in Examples 1-2, and the Kevlar ™ polishing tests were conducted. The results of the tests are also shown in Table 2. Table 3 shows the color changes in the examples -various. Table 2 Table 3 - Dye Color Change It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the products to which it refers.

Claims (17)

CLAIMS Having described the invention as above, the contents of the following claims are claimed as property:

1. A useful adhesive for a fiber optic connection or termination, comprising a) an adhesive component having a viscosity between about 200 centipoise and about 5000 centipoise, b) said adhesive which is curable by exposure to radiation of a length wave from about 400 to about 1100 nanometers, and c) an initiator system for curing the adhesive composition by exposure to said radiation, characterized in that d) a dye which is soluble in the adhesive component, said dye has a first color before exposure to said radiation and a second color after exposure to said radiation, whereby the dye is suitable to show that a space between an optical fiber and a housing is filled with an adhesive prior to curing the adhesive.

2. A colored adhesive useful for an optical fiber connection or termination according to the claim 1, characterized in that said dye is included in the initiator system.

3. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the viscosity is from about 400 centipoise to about 4000 centipoise.

4. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the radiation has a wavelength from about 400 nanometers to about 700 nanometers.

5. A colored adhesive useful for an optical fiber connection or termination according to claim 4, characterized in that the radiation has a wavelength from about 400 to about 600 nanometers.

6. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the composition has a curing start of up to about 60 seconds with the formation of the second color.

7. A colored adhesive useful for an optical fiber connection or termination according to claim 5, characterized in that the composition has a curing start of up to about 30 seconds.

8. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the adhesive component contains at least one acrylate monomer.

9. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the adhesive component contains at least one epoxy resin.

10. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the adhesive component contains at least one epoxy acrylate.

11. A colored adhesive useful for an optical fiber connection or termination according to claim 8, characterized in that the adhesive component contains at least one monomer selected from the group consisting of hydroxypropyl methacrylate, hydroxyethyl methacrylate (IRMA), and acid methacrylic

12. A colored adhesive useful for an optical fiber connection or termination according to claim 1, characterized in that the adhesive comprises a photoinitiator system containing an electron donor and at least one sensitizer.

13. A colored adhesive useful for an optical fiber connection or termination according to claim 12, characterized in that the photoinitiator system comprises at least one fluorone sensitizer.

14. A colored adhesive useful for an optical fiber connection or termination according to claim 13, characterized in that the photoinitiator system additionally comprises a diaryliodonium salt.

15. An optical fiber connector comprising: a) at least one fiber optic cable comprising at least one optical fiber surrounded by a plurality of reinforcing fibers, both of which are surrounded by at least one layer of polymer coating, one portion The cable is stripped in a layered winding such that a terminal end of the exposed fiber is followed by an area of the exposed reinforcing fibers, followed by an area of the coated cable; b) a retention device for the optical cable and c) an adhesive for securing the optical cable with the support, characterized in that the adhesive injected into the retention device is colored and comprises: i) an adhesive component having a viscosity between about 200 centipoise and about 5000 centipoise, ii) a dye which is soluble in the adhesive component, said dye having a first color before exposure to radiation having a wavelength from about 400 to about 1100 nanometers, and a second color after exposure to radiation, whereby the colorant is adequate to show that a space between an optical fiber and a housing is filled with adhesive prior to curing the adhesive, and iii) an initiator system for Curing the adhesive composition by exposure to radiation, optical fiber, reinforcing fibers and the retention device are submitted by means of the exposure ion to radiation when the start of curing occurs within sixty seconds.

16. An optical fiber connector according to claim 15, characterized in that it comprises a plurality of fiber optic cables.

17. An optical fiber connector according to claim 15, characterized in that the optical cable is a multi-fiber belt or band.