KR100482811B1 - Thermal stabilization method of optically transparent waveguide - Google Patents

Abstract

A photopolymerizable composition used to form a photopolymer composition for use in forming a light transmitting site of a device such as a light transmitting device.

Description

Thermal stabilization method of optically transparent waveguide

1A and 1C are schematic cross-sectional views of manufacturing a preferred waveguide according to the present invention.

2 is a perspective view schematically showing the arrangement of a preferred waveguide according to the present invention.

＊ Explanation of symbols for main part of drawing ＊

10 ..... Substrate 12 ..... Layer

14 ..... Mask 16 ..... Beam

18 ..... patterns

The present invention relates to photo-polymerizable compositions and thermally stable photopolymer compositions prepared therefrom. The invention also relates to a light transmissive optical device such as a waveguide formed from the photopolymer composition of the invention.

In an optical communication system, a message is conveyed by a carrier of optical frequencies generated by a light source such as a laser or a light emitting diode. Currently, such an optical communication system has been of interest because it can increase the number of communication channels and have various advantages over conventional communication systems, such as using other materials instead of expensive copper cables for message transmission. This means of conducting or inducing optical vibration waves from one point to another is called an optical waveguide. Optical waveguides are based on the fact that the light transmissive medium is surrounded or bounded by another medium with low refractive index, and the light is introduced along the axis of the inner medium to reflect largely at the interface with the surrounding medium, thus exhibiting a guiding effect. Works on the basis of

Glass formed from fibers of a particular dimension is most often used as material for waveguide devices. However, the use of light-transmissive polymers as light transmissive devices is increasing. However, conventional light-transmissive polymers have some drawbacks. For example, a light transmissive polymer usually has a property of discoloring when heat treated for a long time. The visual effect is the yellowing of the polymer.

Heat discoloration in the polymer is due to a number of factors, such as, for example, a quenching reaction in which the polymer degrades slowly. In general, when the heating for a long time as compared to the case of heating for a short time severely discolored. At first it turns pale yellow, but it may eventually turn brown or even black. By measuring the discolored polymer sample with an absorption spectrophotometer, one can observe the absorption band tail extending from the polymer's original ultraviolet absorption band to the visible spectral region (400 nm-700 nm) and even the ultraviolet spectral region (> 700 nm). have. Typically the absorbent tail is an indistinguishable microstructure. As light is absorbed in the transmissive region, the intensity of light waves passing through the waveguide decreases, which causes a “light output loss”.

In the infrared spectral region of 700-1300 nm, an optical waveguide of mainly multiple modes is used. If the polymer optical waveguide is heated for a long time and the heat-induced absorption band tail extends into the infrared wavelength region, light transmission through the waveguide can be significantly reduced. If it is markedly discolored, the waveguide becomes useless.

The photopolymer coating and waveguide may crack while heated to elevated temperatures.

The waveguide is cracked, scattering light and reducing the overall efficiency of the waveguide. Such cracks are caused by stress. In addition, the stress is caused by the non-uniformity of the photopolymer composition or the substrate or coating material in contact with the waveguide inside the waveguide is different from the waveguide material and the coefficient of thermal expansion.

In the process of forming a photopolymer waveguide on a substrate by UV exposure of the monomer precursor, the waveguide is generally subjected to tensile stress. This is because in general the volume occupied by the photopolymer is smaller than the volume occupied by the monomer precursor. Shrinkage may be about 10%.

Another effect due to temperature changes is the delamination of the waveguide in the substrate. As it is peeled off, the waveguide's characteristics (e.g., numerical aperture or NA) change, weakening the structure of the waveguide and being easily damaged by other environmental factors such as vibration and moisture.

In one aspect, the invention consists of multi-functional aryl acrylates and aryl methacrylates such as aryl acrylates and aryl methacrylates, preferably aryl triacrylates, aryl diacrylates and tetra-acrylates. One or more ethylenically unsaturated monomers selected from the group consisting of: And

Photoinitiators that activate polymerization when the unsaturated monomers are exposed to actinic radiation;

It relates to a photopolymerizable composition comprising a,

The composition was polymerized and exposed to air at 190 ° C. for 24 hours, as measured by ASTM D1544-80, indicating that it was colored to 8 or less using the Gardner Color Scale. When exposed to air at 190 ° C. for 24 hours, ASTM D 4538-90A Based on this, it is possible to form a photopolymer that is not cracked and is not peeled off.

In another aspect, the present invention relates to a photopolymer formed by exposing the photopolymerizable composition according to the present invention to actinic radiation.

In another aspect, the invention relates to a light transmission device such as an optical waveguide comprising a substrate having a predetermined pattern of light transmission sites on a surface of the substrate, which includes a light transmission site comprising a photopolymer according to the invention. It has a main body.

The present invention is advantageous for the polymers currently used in the manufacture of light transmitting devices.

For example. The photopolymers according to the invention exhibit improved thermal stability such that discoloration is reduced after treatment or use at relatively high temperatures (i.e., about -50 to 125 ° C), and therefore high light transmission as compared to thermally labile polymers. This property is particularly advantageous when the photopolymer is used in the manufacture of light transmitting elements in light transmitting devices such as waveguides which are exposed to relatively high temperatures during manufacture. Preferred photopolymers according to the invention have peeling resistance and crack resistance when bonded to a substrate, which is also preferred for the properties of the polymers used in the production of light transmitting elements of light transmitting devices.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The photopolymerizable composition according to the present invention comprises two essential components.

The first essential ingredient is a photopolymerizable ethylenically unsaturated monomer selected from the group consisting of aryl acrylates and aryl methacrylates (아크릴 aryl acrylate monomers).

Examples of such aryl acrylate monomers include, for example, diacrylates based on benzene, naphthalene, bisphenol-A, biphenylene, methane biphenylene, trifluoromethane biphenylene, phenoxyphenylene, Aryl diacrylates such as triacrylates and tetraacrylates, triacrylates and tetraacrylates. Preferred aryl acrylate monomers are multifunctional aryl acrylates and aryl methacrylates and more preferred aryl acrylate monomers are diacrylates, triacrylates and methacrylates based on tetra acrylate and bisphenol-A structures. Most preferred aryl acrylate monomers are ethoxylated bisphenol-A diacrylate and dimethacrylate, propoxylated bisphenol A diacrylate and dimethacrylate and ethoxylated hexafluorobisphenol-A diacrylate and dimetharate. Alkoxylated bisphenol-A diacrylates such as acrylates and dimethacrylates. The aryl acrylate monomers selected are ethoxylated bisphenol-A diacrylates and dimethacrylates.

The amount of aryl acrylate monomers in the composition can vary widely and can be used in amounts commonly used in photopolymerizable compositions used in the production of photopolymers used as light transmitting elements in optical transmission devices.

The amount of aryl acrylate monomer is generally about 35-99.9% by weight of the composition, preferably about 60-98% by weight of the composition and more preferably about 65-95% by weight of the composition.

The photopolymerizable compositions according to the present invention comprise photoinitiator systems which, as other essential ingredients, are activated by actinic radiation to produce activated species that allow the aryl acrylate monomers to photopolymerize.

The photoinitiator system may contain photoinitiators and, preferably, conventional sensitizers, in which the spectral responsiveness extends into regions of spectral utility, such as, for example, the U.V region where the laser is excited and the visible light spectral region. Generally the photo-initiator is an addition polymerization initiator that generates free-radicals activated by actinic radiation and is preferably thermally inert at temperatures below room temperature (eg about 20-25 ° C.). Examples of such initiators include those described in US Pat. No. 4,943,112. Preferred free radical initiators are 1-hydroxy-cyclohexyl-phenylketone (Irgacure 184), benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzophenone, benzidimethyl ketal (Irgacure 651), α, α-di Ethyloxy acetophenone, α, α-dimethyloxy-α-hydroxy acetophenone (Darocur 1173), 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-2- Propane-1-one (Darocur 2959), 2-methyl-1- [4 (methylthio) phenyl] -2-morpholino-propane-1-one (Irgacure 907), 2-benzyl-2-dimethylamino- 1- (4-morpholinophenyl) -butan-1-one (Irgacure 369), poly {1- [4- (1-methylvinyl) phenyl] -2-hydroxy-2-methyl-propane-1- (Esacure KIP), [4- (4-methylphenylthio) -phenyl] phenylmethanone (Quantacure BMS), di-carmpherquinone.

More preferred photoinitiators include benzidimethyl ketal (Irgacure 651), α, α-diethyloxy acetophenol, α, α-dimethyloxy-α-hydroxyacetophenone (Darocur 1173), 1-hydroxycyclohexyl-phenyl Ketone (Irgacure 184), 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-propan-1-one (Darocur 2959), 2-methyl-1- [4- Methylthio) phenyl] -2-morpholino-propane-1-one (Irgacure 907), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one (Irgacure 369) It includes.

The most preferred photoinitiator does not yellow when irradiated and therefore the color value of the composition does not increase to a scale value of 8 or more on a Gardner color scale as measured by ASTM D 150-80 for 24 hours exposure to 190 ° C. Such photoinitiators include benzidimethyl ketal (Irgacure 651), α, α-dimethyloxy-α-hydroxy acetophenone (Darocur 1173), 1-hydroxy-cyclohexyl-phenyl ketone (Irgacure-184) and 1- [ 4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-propan-1-one (Darocur 2959).

The amount of photoinitiator use may vary widely but may be used in conventional amounts. Generally, the photoinitiator amount is about 0.1-10% by weight of the composition. The amount of photoinitiator is preferably about 0.5-10% by weight, more preferably about 0.5-5% by weight, based on the total weight of the composition.

The composition according to the present invention may comprise not only the essential components, but also various optical components typically used in photopolymerizable compositions used in the production of photopolymers used as light transmitting elements of light transmitting devices. Such optical components are well known in the art and include stabilizers, inhibitors, plasticizers, optical gloss agents, mold release agents, chain transfer agents, other photopolymerizable monomers, and the like.

The composition according to the invention preferably comprises one or more other photopolymerizable monomer components in addition to the essential aryl acrylate monomers.

Without unduly degrading the basic properties provided by aryl acrylate monomers, such as, for example, the ability to reduce discoloration, crack peeling of photopolymers formed from the composition, for example crosslink density, viscosity, adhesion, cure rate and Other monomer components can be used to control the properties of the composition, such as controlling the refractive index and the like. Other monomers include photopolymerizable aliphatic ethylenically unsaturated monomers, preferably acrylate or methacrylate monomers, more preferably multifunctional acrylate or methacrylate monomers. Examples of useful non-essential monomer components include butyl acrylate (BA), ethylhexyl acrylate (EHA), phenoxyethyl acrylate (PEA), β-carboxyethyl acrylate (β-CEA), isobornyl acrylate (IBOA) ), Tetrahydrofurfuryl acrylate (THFFA), cyclohexyl acrylate (CHA), propylene glycol monoacrylate (MPPGA), 2- (2-ethoxyethoxy) ethyl acrylate (EOEOEA), N-vinyl P Lollidon (NVP), 1,6-hexanediol diacrylate (HDPA) or dimethacrylate (HDDMA), neopentyl glycol diacrylate (NPGDA), diethylene glycol diacrylate (DEGDA) or dimethacryl Rate (PEGDMA), triethylene glycol diacrylate (TEGDA) or dimethacrylate (TEGDMA), tetraethylene glycol diacrylate (TTEGDA) or dimethacrylate (TTEGDMA), polyethylene glycol diacrylate (PEGDA) or Dimethacryl (PEGDMA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA) ), Aliphatic diacrylate (ADA), alkoxylated aliphatic diacrylate (AADA), aliphatic carbonate diacrylate (ACDA), trimethylolpropane triacrylate (TMPTA) or trimethacrylate (TMPTMA), Pentaerytriol triacrylate (PETA), ethoxylated trimethylolpropane triacrylate (TMPEOTA), propoxylated trimethylolpropane triacrylate (TMPPOTA), glyceryl proxylated triacrylate (GPTA), Tris (2-hydroxyethyl) isocyanurate triacrylate (THEICTA), pentaerythrirol tetraacrylate (PETTA), dipentaerytriol pentaacrylate (D PEPA), ditrimethylol propane tetraacrylate (DTMPTTA), and alkoxylated tetraacrylate (ATTA). The most preferred monomers as non-essential components are trimethylol propane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), pentaerytriol triacrylate (PETA), ethoxylated trimethylolpropane tri Acrylate (TMPEOTA), Glyceryl Proxylated Triacrylate (GPTA), Pentaerythriol Tetraacrylate (PETTA), Dipentaerytriol Pentaacrylate (DPEPA), Ditrimethylolpropane Tetraacrylate (DTMPTTA ).

The total amount of other monomer components in the composition can vary widely and is generally about 0-65% by weight of the composition, preferably about 0-40% by weight of the composition, more preferably about 0-35% by weight of the composition. .

The photopolymerizable composition according to the present invention was thermally aged at 190 ° C. for 24 hours in air as specified in ASTM D 4538-90A, and thus yellowed after thermal aging (Gardner Color Scale. As measured by ASTM D 1544-80). It is preferable to include a stabilizer in order to prevent or reduce the sensitization of deterioration of characteristics such as cracking and peeling after the above coloring). Such stabilizers include UV absorbers, light stabilizers and antioxidants. UV absorbers include 2- [2-hydroxy-3,5-di (1,1-dimethylbenzyl) phenyl] -2-H-benzotriazole (Tinuvin 900), poly (oxy-1,2-ethanediyl ), α- (3- (3- (2H-benzitriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxyphenyl) -1-oxopropyl) -ω-hydroxy Hydroxyphenyl benzotriazoles such as hydroxy (Tinuvin 1130) and 2- [2-hydroxy-3,5-di (1,1-dimethylpropyl) phenyl] -2-H-benzotriazole (Tinuvin 238) and Hydroxybenzophenones such as 4-methoxy-2-hydroxybenzophenone and 4-n-octoxy-2-hydroxybenzophenone. Light stabilizers include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, 4-benzoyloxy-2 , 2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770), bis (1,2,2,6,6 -Pentamethyl-4-piperidinyl) sebacate (Tinuvin 292), bis (1,2,2,6,6-pentamethyl-4-piperidinyl) -2-n-butyl-2- (3, 5-di-tert-butyl-4-hydroxybenzyl) malonate (Tinuvin 144), succinic acid and N-β-hydroxy-ethyl-2,2,6,6-tetramethyl-4-hydroxy-piperi Hindered amines such as succinic acid polyester (Tinuvin 622) with Dean (Tinuvin 622). Antioxidants include 1,3,5-trimethyl-2,4,6-tris ((3,5-di-tert-butyl) -4-hydroxybenzyl) benzene, 1,1,3-tris- (2 -Methyl-4-hydryl-5-tert-butylphenyl) butane, 4,4'-butylidene-bis- (6-tert-butyl-3-methyl) -phenol, 4,4'-thiobis- (6-tert-butyl-3-methyl) phenol, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, cetyl-3,5-di-tert-butyl-4 Hydroxybenzene (Cyasorb UV 2908), 3,5-di-tert-butyl-4-hydroxybenzoic acid, 1,3,5-tris- (tert-butyl-3-hydroxy-2,6-dimethylbenzyl (Cyasorb 1790), stearyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076), pentaerythritol tetrabis (3,5-di-tert Substituted phenols such as -butyl-4-hydroxyphenyl) (Irganox 1010), thiodiethylene-bis- (3,5-di-tert-butyl-4-hydroxy) hydrocinnamate (Irganox 1035) do. Preferred stabilizers used in the present invention are antioxidants.

Preferred antioxidants are 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl) -4-hydroxybenzyl) benzene, 1,1,3-tris- (2- Methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4'-butylidene-bis- (6-tert-butyl-3-methylphenol), 4,4'-thiobis- (6 -tert-butyl-3-methylphenol), tris- (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, cetyl-3,5-di-tert-butyl-4-hydrate Cyasorb UV 2908, 3,5-di-tert-butyl-4-hydroxybenzoic acid, 1,3,5-tris-tert-butyl-3-hydroxy-2,6-dimethylbenzyl (Cyasorb 1790 ), Stearyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076), pentaerytriol tetrabis (3,5-di-tert-butyl-4 -Hydroxyphenyl) (Irganox 1010), thiodiethylene-bis- (3,5-di-tert-butyl-4-hydroxy) hydrocinnamate (Irganox 1035).

Most preferred stabilizers include pentaerytriol tetrabis (3,5-di-tert-butyl-4-hydroxyphenyl) (Irganox 1010), thiodiethylene-bis- (3,5-di-tert-butyl- 4-hydroxy) hydrocinnamate (Irganox 1035) and stearyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076).

The amount of stabilizing agent in the composition can vary widely and is generally about 0.1-10% by weight of the composition. The amount outside the stabilizer is preferably about 0.1-5% by weight of the composition, more preferably about 0.2-3% by weight of the composition.

The polymerizable composition of the present invention is useful as a precursor used to form the photopolymer of the present invention. Photopolymers according to the present invention are typically prepared by exposing the copolymerizable compositions of the present invention to actinic radiation of the required wavelength and intensity for the required period of time. As used herein, “chemical radiation” refers to light such as electron beams, ionic or neutron beams, or X-ray radiation, as well as visible, ultraviolet, or infrared spectral regions. The actinic radiation can be incoherent light or coherent light, for example laser light.

The light source of the actinic rays and the method of exposure, time, wavelength and intensity can vary widely depending on the degree of polymerization required, the refractive index of the photopolymer and other factors known to those skilled in the art. Conventional photopolymerization processes and their operating parameters are well known in the art. For example, S.P.Pappas Ed. Radiation Curing: Science and Technology Plenum Press, New York, NY; D. R. Radell Ed., Radiation Curing of Polymers, 11, Royal Society of Chemistry, Cambridge, Mass; And C.E. Hoyle and J.E.Kristle, Ed., Radiation Curing of Polymeric Materials, American Chemical Society. therefore. It is not described in detail herein.

The photopolymer according to the invention has several advantages over the conventional polymers used for the production of light transmitting elements in light transmitting devices. For example, the use of essential aryl acrylate monomers results in less discoloration when exposed to ambient temperatures of about 190 ° C. for 24 hours compared to other photopolymers. The degree of discoloration by the Gardner Color Scale is generally about 8 or less, preferably about 6 or less, more preferably about 5 or less and most preferably measured by ASTM D 1544-80 for 24 hours at 190 ° C. About 3 or less. The photopolymer according to the present invention does not crack or peel off or substantially crack or crack when formed in a glass substrate with a thickness of 10-200 microns and exposed to air at 190 ° C. for 24 hours by ASTM D 4538-90A. It does not peel off. The heat-treated sample was visually observed at a microscope of 50 x magnification so that the photopolymer coating did not crack and peel off. The unique properties of the photopolymers are believed to be due to the use of essential aryl acrylate monomers.

The photopolymer according to the invention can be used for the production of light transmitting elements in optical devices. Examples of such devices include planar optical slab waveguides, channel type optical waveguides, optical couplers, micro-optic elements, and the like; 4,877,717 and 5,136,682. In a preferred embodiment of the invention, the polymerizable compositions and photopolymers according to the invention are for example US having organic optical waveguides such as slab, channel type and rib waveguides and light transmitting elements made from the photopolymers according to the invention. It can be used to manufacture an optical waveguide coupling device as described in patent 4,609,252. In a more preferred embodiment of the present invention, the waveguide is in the form of a substrate having a waveguide strip or waveguide layer on one surface thereof.

Such waveguides are formed by applying to the surface of a suitable substrate a thin or thick coating of the polymerizable composition according to the invention. The coating can be formed by a variety of methods known in the art, such as spin coating, needle coating, roller coating, doctor blading, and evaporation.

The substrate can be any material desired for waveguide formation, including semiconductor materials such as silicon, silicon arsenide gallium oxide, silicon nitride, glass, quartz, plastics, ceramics, crystalline materials.

The substrate may or may not contain topographical forms such as grooves or electrical circuits or other devices such as electro-optical devices such as laser diodes.

In a substrate having an organic layer in which the light transmitting portion has a lower refractive index than the substrate material, a layer having a lower refractive index than the organic waveguide material should be formed first. Such layers are known in the art as buffer layers and can be composed of semiconductor oxides, low refractive index polymers or spin-on silicon dioxide glass materials.

Once the copolymerizable composition is formed into a thin or thick film on the substrate, actinic radiation is directly irradiated on the thin film to delineate the light transmissive site.

Delineating means that the location and dimensions of the light transmitting device are determined by the pattern of actinic radiation irradiated on the coating surface on the substrate. Patterned radiation should be chosen such that the photopolymerizable composition polymerizes into the desired pattern and other portions of the coating remain unreacted.

The light source of actinic radiation and the wavelength of radiation can be varied widely and conventional wavelengths and light sources can be used. It is desirable that photochemical excitation be performed with relatively short wavelength (or high energy) radiation such that light exposure (eg, room light) which is typically experienced before treatment does not polymerize the photopolymerizable material too early.

It can also be processed in a multiphoton process initiated by a high intensity actinic radiation source such as a laser. Therefore, it is desirable to expose to ultraviolet (300-400 nm wavelength). It is also useful to expose to far ultraviolet rays (wavelengths 190-300 nm). A convenient light source is a high pressure xenon or mercury-xenon arc lamp equipped with an appropriate optical filter to select the wavelength required for the process. Shortwave interference radiation is also useful in the practice of the present invention. Argon ion lasers operating in a “UV” mode at several wavelengths near 350 nm are preferred. Also preferred is a frequency-doubled argon ion laser output near the 257 nm wavelength. Electron beams or ion beams may also be used.

Controlling the spatial profile of actinic radiation in a layer of photopolymerizable material is possible in a conventional manner. For example, as one conventional method, a mask having a necessary light transmission pattern is inserted between a light source of actinic radiation and a photopolymerizable composition film.

The mask has a transparent portion and an opaque portion such that the radiation is applied only to the required portion of the coating surface. Mask exposure, which exposes a thin film through a mask, is well known in the art and may include contact, proximity, and injection methods for "printing" light transmission patterns onto a coating.

In other conventional spatial control methods, actinic radiation sources including direct or concentrated beams such as laser or electron beams are used.

Such a beam would only traverse a narrow area of the coating surface of the photo-polymerizable material. The required light transmissive partial pattern can be formed by scanning the beam in space or by moving the substrate so that the intersected portion changes for a stationary beam, moving many small intersections around the coating surface.

Such a method of exposure using a beam light source is known in the art as a "divect-write" method.

By selecting the spatial characteristics of the radiation it is possible to form a light transmitting portion on the surface of the substrate, for example slabs and channel waveguides. In slab waveguides, the light waves are only confined to the encapsulation surface, while in channel waveguides, the light waves are confined laterally within the encapsulation. Channel structures not only allow light to be directed directly to a specific area of the substrate, but also provide a mechanism by which light waves are split and combined, which is necessary for many nonlinear and electro-optical devices. After the photopolymerizable composition is polymerized on the substrate surface in a predetermined pattern of the photopolymer according to the present invention, the pattern is developed so that the predetermined pattern remains. For example, conventional printing methods such as the conventional photolithographic method described by William S. De Forest in Photoresist Materials ana Process, McGraw-Hill Company, New York (1975) can be used.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

1 shows a substrate 10, such as glass or molten quartz, having a photopolymerizable composition according to the invention forming layer 12 on the substrate surface. The composition of the copolymerizable material can be changed to give the necessary waveguide properties to the final device, but it is preferable that the photopolymer according to the present invention transmits a light wave of 400-1600 nm and has a refractive index of about 1.40-1.60. . At this time, the apparatus according to the present invention can accommodate optical fibers having various refractive indices. The organic layer 12 may be deposited by any suitable conventional method, such as, for example, immersing the substrate 10 in a solution of the photoactive composition. The photopolymerizable composition may be deposited to a thickness of 5-500 μm to form a device miscible with conventional glass and plastic fibers having a light carrier core typically of 5-500 μm in diameter. The deposited photopolymerizable composition may be washed with acetone and removed from the backside (or bottom) of substrate 10 as shown in FIG. Optionally, a copolymerizable composition deposited on the backside of the substrate may be left.

Thereafter, for example, the structure shown in FIG. 1 by the well-known photographic plate method described by William S. DeForest, Photoresist Materials and Processes, McGraw-Hill Book Company, New York, 1975, is placed at a distance of 1-10 μm from substrate 10. It was exposed to ultraviolet beam 18 through a positioned off-contact mask 14 and limited to the required form of the final device as shown in FIG. 1 to allow the photopolymerizable composition to polymerize into a waveguide photopolymer. Deposition and irradiated layer 12 were developed with a suitable solvent to remove unnecessary unpolymerized portions. Pattern 18 of the exposed photopolymerizable composition deposited on substrate 10 is confined to mask 14.

2 shows a preferred embodiment of the present invention formed in the shape of a Y plane in the predetermined planar shape of the device. Substrate 10 has a waveguide pattern 18 deposited on the substrate in the manner as described for FIG. 1 using a mask in the Y-shape with mask 14 shown in FIG. The device shown in FIG. 2 is used as a waveguide coupler.

Comparative Example 1

10 parts of Genomer T-1600 (viscosity 48,000 mPa, trifunctional polyester urethane acrylate from Biddle-Sawyer), 20 parts of 1,6-hexanediol diacrylate (HDDA, Scientific Polymer Products) and Darocur 1173 (α) 0.2 parts of α-dimethyloxy-α-hydroxy acetophenone, EM Industries), 0.2 parts of Irgacure 500 (a 1: 1 weight ratio of 1-hydroxycyclohexyl-phenylketone and benzophenone, Ciba-Geigy) And a liquid photoinitiator mixture of 0.6 parts of 0.2 parts Irgacure 651 (Ciba-Geigy, Benjidimethyl Ketal) was prepared and filtered through a 0.2 micron Teflon membrane. The liquid mixture was sprayed onto a glass plate to form a 0.2 mm thick layer, and under nitrogen cover, the layer was irradiated with UV radiation having an intensity of 25 mW / cm 2 for 0.5 minutes from a medium pressure mercury lamp. After irradiation the liquid layer turned into a solid coating. The coated substrate was then placed in an air circulation oven and thermally aged at 190 ° C. for 24 hours. The air doubled acceleration was set to 101 / h. The color of the aged sample was dark brown with a Gardner Color Scale of 18 or more as defined in ASTM D 1544-80. It did not delaminate from the substrate as defined in ASTM D 4538-90a, indicating that the layer did not crack. The test results are shown in Table 1 below.

Comparative Example 2

The same test procedure as in Comparative Example 1 was repeated except that HDDA was replaced with IBOA (isobonyl acrylate, Scientific Polymer Products). The color of the aged sample was dark brown with a Gardner color scale of 18 or higher.

It was not peeled off the substrate and the layer showed no cracking. The test results are shown in Table 1 below.

Comparative Example 3

The same test procedure as in Comparative Example 1 was repeated except that HDDA was replaced with TMPTA (Trimethylolpropane triacrylate, Scientific Polymer Products).

The color of the aged sample was dark brown with a Gardner color scale of 18 or higher.

It did not peel off the substrate and the layer showed no cracking. The test results are shown in Table 1 below.

Comparative Example 4

The same procedure as in Comparative Example 1 was repeated except that Genomer T-1600 was replaced with Genomer T-1200 (trifunctional polyester urethane acrylate, Biddle-Sawyer, viscosity 75,000 mPa). The color of the aged samples was dark brown with a Gardner color scale of 18 or higher. It did not peel off the substrate and the layer showed no cracking. The test results are shown in Table 1 below.

Comparative Example 5

The same procedure as in Comparative Example 1 was repeated except that Genomer T-1600 was replaced with Genomer T-1030 (trifunctional polyester urethane acrylate, Biddle-Sawyer). The color of the aged samples was light brown with a Gardner color scale of 5 or higher.

The polymer layer was peeled off the glass plate and the glass plate was slightly cracked. The test results are shown in Table 1 below.

Comparative Example 6

The test procedure was repeated as in Comparative Example 1, except that Genomer T-1600 was replaced with Ebercyl 8800 (an oligomeric aliphatic urethane acrylate having a functional level of 2.5, Radcure). The color of the aged sample was dark brown with a Gardner color scale of 18 or higher.

The polymer layer was peeled off from the glass plate and slightly cracked. The test results are shown in Table 1 below.

Table 1

Comparison of oligomeric acrylates containing polyurethane segments after heat-aging at 190 ° C. for 24 hours

(1) Discoloration was measured by the Gardner Color Scale in accordance with ASTM D 1544-80.

(2) Peeling was measured based on ASTMD 4538-90a.

(3) The cracks were measured according to ASTM D 4538-90a.

Comparative Example 7

A liquid mixture was prepared containing 10 parts of Scientific Polymer Products. Ethoxylated trimethylolpropane triacrylate (TMPEOTA) and 0.2 part of a liquid photoinitiator mixture of 0.066 parts of Darocur 1173, 0.066 parts of Irgacure 500 and 0.066 parts of Irgacure 651. The photocuring and thermal test procedure in Example 1 was then repeated. The aged siro was light brown, rated 12 on the Gardner color scale.

The polymer layer peeled off from the glass plate and became extremely overheated. The test results are shown in Table 2 below.

Comparative Example 8

The same test procedure as in Comparative Example 7 was repeated except that TMPEDTA was replaced with TMPTA (Scientific Polymer Products, trimethylolpropane triacrylate).

The color of the aged sample was pale yellow, grade 6 on the Gardner color scale.

The polymer layer was peeled off from the glass plate and severely cracked. The test results are shown in Table 2 below.

Comparative Example 9

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with NPPOGDA (Scientific Polymer Products, propoxylated neopentyl glycol diacrylate). The color of the aged samples was light brown with a Gardner color scale of grade 13 or higher.

The polymer layer was peeled and cracked in the glass plate.

The test results are shown in Table 2 below.

Comparative Example 10

The same test procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with GPTA (Scientific Polymer Products, Glyceryl Proxyized Triacrylate). The photocuring and thermal test procedure of Example 1 was then repeated. The color of the aged samples was brown with a Gardner color scale of 16 grades. The polymer layer was peeled and cracked in the glass plate.

The test results are shown in Table 2 below.

Comparative Example 11

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with TPGDA (Scientific Polymer Products, tripropylene glycol diacrylate). The color of the aged sample was light brown, grade 14 on the Gardner color scale. The polymer layer was peeled off and slightly cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 12

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with PEG 200DA (Scientific Polymer Products, polyethylene glycol-200 diacrylate).

The color of the aged sample was light brown, grade 13 on the Gardner color scale.

The polymer layer was peeled off and slightly cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 13

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with PEG 400DA (Scientific Polymer Products, polyethylene glycol-400 diacrylate).

The color of the aged samples was pale brown with a 16 grade Gardner color scale.

The polymer layer was peeled and cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 14

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with DTMPTTA (Scientific Polymer Products, ditrimethylolpropane triacrylate). The color of the aged sample was yellow, grade 8 on the Gardner color scale.

The polymer layer was peeled and cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 15

The same test procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with HDDA. The color of the aged sample was pale yellow, grade 6 on the Gardner color scale.

The polymer layer was peeled and cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 16

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with a mixture containing 7 parts of CN-112C60 (Sartamer, ethoxylated noblock acrylate) and 3 parts of TMPTA. The photocuring and thermal test procedure of Example 1 was then repeated. The color of the aged samples was light brown, grade 12 on the Gardner color scale. The polymer layer was peeled off from the glass plate and did not crack. The test results are shown in Table 2 below.

Comparative Example 17

The same test procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with a mixture containing 7 parts of AS-X95 (Biddle-Sawyer, oligomeric polyester acrylate) and 3 parts of HDODA. The color of the aged sample was pale brown, 8th grade on Gardner color scale.

The polymer layer is peeled off and slightly cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 18

The same test procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with SR 9008 (Sartomer, trifunctional alkoxylated acrylate). The color of the aged sample was yellow, grade 8 on the Gardner color scale. The polymer layer was peeled off from the glass plate and did not crack. The test results are shown in Table 2 below.

Comparative Example 19

The same test procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with SR 9012 (Sartomer, trifunctional oligomeric polyester acrylate). The color of the aged sample was yellow, grade 6 on the Gardner color scale. The polymer layer was peeled and cracked in the glass plate. The test results are shown in Table 2 below.

Comparative Example 20

The same procedure as in Comparative Example 7 was repeated except that TMPEOTA was replaced with a mixture containing 7 parts of TITA (Scientific Polymer Products, Tris- (2-hydroxyethyl) isocyanurate triacrylate) and 3 parts of HDDA. It was. The color of the aged samples was light brown, grade 12 on the Gardner color scale. The polymer layer was peeled and cracked in the glass plate.

The test results are shown in Table 2 below.

TABLE 2

(1) Discoloration was measured by the Gardner Color Scale in accordance with ASTM D 1544-80.

(2) Peeling was measured based on ASTMD 4538-90a.

(3) The cracks were measured according to ASTM D 4538-90a.

Example 4

The test procedure of Comparative Example 7 was repeated except that 10 parts of TMPEOTA were replaced with a mixture of 6.6 parts of EBDA and 3.4 parts of HDDA. The color of the aged sample was yellow with grades 8-9 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack.

The test results are shown in Table 3 below. Prior to photocuring the liquid composition was deposited on a glass or silicon substrate by spin-coating. Depending on the spinning speed the thickness of the photocured polymer could be controlled to 0.5-5 microns.

Example 5

The test procedure of Comparative Example 7 was repeated except that 10 parts of TMPEOTA were replaced with a mixture of 6.6 parts of EBDA and 3.4 parts of TMPTA. The color of the aged sample was pale yellow, rated 5-6 on a Gardner color scale. The polymer layer attached to the glass plate did not peel and crack.

The test results are shown in Table 3 below. Prior to photocuring the liquid composition was deposited on a glass or silicon substrate by spin-coating. Depending on the spinning speed the thickness of the photocured polymer could be controlled to 0.5-5 microns.

Example 6

The test procedure of Comparative Example 7 was repeated except that 10 parts of TMPEOTA was replaced with a mixture of 6.6 parts of EBDA and 3.4 parts of ethoxylated trimethylol propane triacrylate (ETMPTA). The color of the aged sample was yellow with 8-9 grade on Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 3 below.

Prior to photocuring the liquid composition was deposited on a glass or silicon substrate by spin-coating. Depending on the spinning speed the thickness of the photocured polymer could be controlled to 0.5-5 microns.

Example 7

The test procedure of Comparative Example 7 was repeated except that 10 parts of TMPEOTA was replaced with a mixture of 6.6 parts of EBDA and 3.4 parts of SR 9012 (Sartamer). The color of the aged sample was yellow with a 8-9 grade on the Gardner color scale. The polymer layer peeled and cracked in the glass plate.

The test results are shown in Table 3 below.

TABLE 3

(1) Discoloration was measured by the Gardner Color Scale in accordance with ASTM D 1544-80.

(2) Peeling was measured based on ASTMD 4538-90a.

(3) The cracks were measured according to ASTM D 4538-90a.

Example 8

The test procedure of Example 5 was repeated except that 0.05 part of Tinuvan 770 (bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, Ciba-Geigy) was added. Tinuvan 770 is a hindered amine stabilizer. The color of the aged sample was yellow, grade 9-10 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack.

The test results are shown in Table 4 below.

Example 9

The test procedure of Example 5 was repeated except that 0.05 part of AM 806 (Ferro Corp.) was added. AM 806 is also a hindered amine light stabilizer. The color of the aged sample was yellow, grade 9-10 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 10

Test of Example 5, except that 0.05 part of Tinuvan238 (2- [2-hydroxy-3,5-di (1,1-dimethylpropyl) phenyl] 2-H-benzotriazole, Ciba-Geigy) was added The procedure was repeated.

Tinuvan 238 is a benzotriazole UV absorber. The photocuring material took 2 minutes.

The color of the aged sample was yellow with 8-9 grade on Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 11

The test procedure of Example 5 was repeated except that 0.05 part of AM 340 (Ferro Corp.) was added. AM 340 is also a benzotriazole UV absorber. The photocuring material took 2 minutes. The color of the aged sample was yellow, grade 9-10 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 12

The test procedure of Example 5 was repeated except that 0.05 parts of Irganox 1010 (Ciba-Geigy, pentaerythritol tetrakis [3,5-di-tert-butyl-4-hydroxyhydrocinnamate]) was added. . Irganox 1010 is an antioxidant in the form of hindered phenols. The color of the aged sample was only very slightly discolored to the grade 2-3 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 13

The test procedure of Example 5 was repeated except that the amount of Irganox 1010 was reduced to 0.01 parts. The color of the aged sample was only very slightly discolored, corresponding to grade 2-3 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 14

The test procedure of Example 5 was repeated except that 0.05 parts of Irganox 1035 (Ciba-Geigy, Thio (diethylene-bis (3,5-di-tert-butyl-4-hydroxy) hydrocinnamate) was added. Irganox 1035 is a hindered phenolic antioxidant, and the color of the aged sample is slightly discolored to the grade 3-4 on the Gardner color scale The polymer layer attached to the glass plate does not peel and crack. Is shown in Table 4 below.

Example 15

The test procedure of Example 5 was repeated except that 0.05 parts of Irganox 1076 (Ciba-Geigy, stearyl-3- [3,5-di-tert-butyl-4-hydroxyphenyl] propionate) was added. . Irganox 1076 is an antioxidant in the form of hindered phenols. The color of the aged sample was very slightly discolored to the grade 2-3 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 16

The test procedure of Example 5 was repeated except that 0.05 parts of Irganox 1520 (Ciba-Geigy, 2,4-bis [octylthiomethyl] -0-cresol) was added. Irganox 1520 is an antioxidant in the form of hindered phenols. The color of the aged sample was slightly discolored to the grade 4-5 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 17

The test procedure of Example 5 was repeated except that 0.05 parts of Cyasorb UV 2908 (American Cyanamid, cetyl-3,5-di-tert-butyl-4-hydroxybenzene) was added. Cyasorb UV 2908 is a hindered phenolic antioxidant. The color of the aged sample was very slightly discolored to the grade 2-3 on the Gardner color scale. The polymer layer attached to our plate did not peel and crack. The test results are shown in Table 4 below.

Example 18

The test procedure of Example 5 was repeated except that 0.02 parts of Irganox 1010, 0.05 parts of Tinuvin 770 and 0.05 parts of Tinuvin-238 were added. Irganox 1010 is an antioxidant in the form of a hindered phenol, Tinuvan 770 is a hindered amine light stabilizer and Tinuvan 238 is a benzotriazole UV absorber. Photocuring took 2 minutes to complete. The color of the aged samples was yellow, corresponding to grades 7-8 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Example 19

The test procedure of Example 5 was repeated except that 0.02 parts of Irganox 1010 and 0.05 parts of Tinuvin 770 were added. Irganox 1010 is an antioxidant in the form of a hindered phenol and Tinuvin 770 is a hindered amine light stabilizer. The color of the aged sample was very slightly discolored to the grade 3-4 on the Gardner color scale. The polymer layer attached to the glass plate did not peel and crack. The test results are shown in Table 4 below.

Table 4

(1) Discoloration was measured by the Gardner Color Scale in accordance with ASTM D 1544-80.

(2) Peeling was measured based on ASTMD 4538-90a.

(3) The cracks were measured according to ASTM D 4538-90a.

(4) When the benzotriazole UV absorber was used as the additive, the photocuring rate was decreased.

(5) Another additive-Tinuvan 770 was added.

Example 20

Photosensitive monomer mixture consisting of 96 parts of ethoxylated bisphenol A diacrylate, 33 parts of trimethyl propane triacrylate, 3 parts of Irganox 1010, 1 part of Darocur 1173, 1 part of Irgacure 651 and 1 part of Irgacure 500 After developing with acetone to prepare an optical waveguide having a length of 5cm. The waveguide was twisted together with 100/140 micron glass optical fibers, 58% by weight of the monomer mixture and Genomer T1600, 50 parts of urethane acrylate, 98 parts of 1,6-hexanediol diacrylate, 1 part of Darocur 1173, Irgancure 651 It was coated with a reaction monomer mixture of 42 parts by weight of a mixture of 1 part and 1 part of Irgacure 500. As the substrate for the polymer optical waveguide, a polyimide circuit board material having a thin layer of a 58:42 mixture as described above was used. Both the substrate coating and the coating layer were cured by blanket exposure from a UV xenon lamp under nitrogen atmosphere.

810 nm laser light was connected to one end of the polymer optical waveguide through a glass fiber optic pigtail. A glass optical fiber attached to the opposite end of the polymer waveguide was connected to a silicon photodetector connected to the photometer to measure the power transmitted through the waveguide. After obtaining the initial transmission power of the polymer optical waveguide, the substrate with the polymer waveguide was placed on a heating plate and heated to 190 ° C., and the temperature was measured with a thermocouple element on the substrate following the attached polymer optical waveguide.

The temperature of the polymer optical waveguide was maintained at 190 ° C. for a total of 45 hours, after which the 810 nm laser light was further projected onto the polymer waveguide and the power was measured again.

The difference between the two power measurements was obtained and divided by the length of the waveguide by 5 cm to determine that the loss of the polymer waveguide was increased by only 0.13 dB / cm despite the increase in the exposure time to the high temperature treatment. This indicates that the waveguide material has a high resistance to thermal degradation of its optical properties.

Claims (17)

A photopolymerizable patterned photopolymer on a substrate formed by photopolymerizing a photopolymerizable composition, wherein the photopolymerizable composition comprises 1,6-hexanedioldiacrylate, trimethylolpropane triacrylate, pentaerytriol triacrylate, ethoxy Group consisting of cylatized trimethylolpropane triacrylate, glyceryl, propoxylated triacrylate, pentaerytriol tetraacrylate, dipentaerytriol pentaacrylate and di (trimethylolpropane) tetraacrylate At least one photoinitiator capable of active polymerization of said monomer and at least one unsaturated monomer selected from said photopolymerizable composition being exposed to actinic radiation and ethoxylated bisphenol A diacrylate, ethoxy to said photopolymerizable composition. Citric Hexafluorobisphenol A Diacrylate At least one ethylenically unsaturated monomer selected from the group consisting of chlorinated and propoxylated bisphenol A diacrylate is incorporated at about 35-99.9% by weight of the photopolymerizable composition, the photopolymer being in air at 190 ° C. A method of thermally stabilizing optically transparent waveguides with a Gardner Color Scale staining of 8 or less as measured by ASTM D1544-80 upon 24 hour exposure. The method of claim 1, wherein the coloring is about 6 or less on a Gardner color scale. The method of claim 1, wherein the coloring is about 5 or less on a Gardner color scale. The method of claim 1 wherein the ethoxylated bisphenol A diacrylate is present. The method of claim 1 wherein ethoxylated hexafluoro bisphenol A diacrylate is present. The method of claim 1 wherein propoxylated bisphenol A diacrylate is present. The method of claim 1, wherein the photoinitiator is benzyl dimethyl ketal; α, α-dimethyloxy-α-hydroxy acetophenone; 1-hydroxycyclohexyl-phenylketone; 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-propan-1-one; Benzophenones; Benzoin; Benzoin ethyl ether; Benzoin isopropyl ether; α, α-diethyloxy acetophenone; 2-methyl-1- [4 (methylthio) phenyl] -2-morpholino-propan-1-one; 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one; Poly {1- [4- (1-methylvinyl) phenyl] -2-methyl-poropan-1-one; [4- (4-methylphenylthio) -phenyl] phenylmethanone; And a free radical photoinitiator selected from the group consisting of di-camphorquinone. 8. The method of claim 7, wherein the photoinitiator is benzyl dimethyl ketal; α, α-diethyloxyacetophenone; α, α-dimethyloxy-α-hydroxy acetophenone; 1-hydroxycyclohexyl-phenylketone; 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-propan-1-one; Benzophenones; 2-ethyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one; And free radical photoinitiator selected from the group consisting of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one. The method of claim 8, wherein the photoinitiator is selected from benzidimethyl ketal; α, α-dimethyloxy-α-hydroxy acetophenone; 1-hydroxy-cyclohexyl-phenyl ketone; 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-propan-1-one; And a free radical photoinitiator selected from the group consisting of benzophenones, The method of claim 1 wherein the photopolymerizable composition further comprises an additional aliphatic ethylenically unsaturated monomer. The method of claim 10 wherein the aliphatic ethylenically unsaturated monomer is selected from the group consisting of acrylate monomers and aliphatic methacrylate monomers. 12. The aliphatic ethylenically unsaturated monomer of claim 11 wherein the aliphatic ethylenically unsaturated monomer is aliphatic diacrylate, aliphatic treacrylate. And aliphatic tetraacrylate, aliphatic dimethacrylate, aliphatic trimethacrylate and aliphatic tetramethacrylate. 13. The method of claim 12, wherein the aliphatic ethylenically-unsaturated monomer is selected from the group consisting of aliphatic diacrylates, aliphatic triacrylates and aliphatic tetraacrylates. The method of claim 1 wherein the composition further comprises a stabilizer. 15. The method of claim 14, wherein said stabilizer is an antioxidant. The method of claim 15, wherein the antioxidant is selected from 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl) -4-hydroxybenzyl) benzene; 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane; 4,4'-butylidene-bis- (6-tert = butyl-3-methylphenol); 4,4'-thiobis- (6-tert-butyl-3-methylphenol); Tris- (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate; Cetyl-3,5-di-tert-butyl-4-hydroxybenzene; 3,5-di-tert-butyl-4-hydroxybenzoic acid; 1,3,5-tris-tert-butyl-3-hydroxy-2,6-dimethylbenzyl; Stearyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; Pentaerytriol-tetrabis (3,5-di-tert-butyl-4-hydroxyphenyl); And a substituted phenol selected from the group consisting of thiodiethylene-bis- (3,5-di-tert-butyl-4-hydroxy) hydroxycinate. The method of claim 16, wherein the antioxidant is selected from stearyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; Pentaerytriol-tetrabis (3,5-di-tert-butyl-4-hydroxyphenyl); And a substituted phenol selected from the group consisting of thiodiethylene-bis- (3,5-di-tert-butyl-4-hydroxy-hydro) cinnamate.