MXPA97003378A

MXPA97003378A - Intermediate glass of self-adhesive safety glass of polivin chloride

Info

Publication number: MXPA97003378A
Application number: MXPA/A/1997/003378A
Authority: MX
Inventors: A Parker Anthony
Original assignee: Libbeyowensford Company
Priority date: 1994-11-09
Filing date: 1997-05-08
Publication date: 1997-08-01

Abstract

Laminated safety glass that includes a pair of glass sheets (10) units together with a self-adhesive composite intermediate layer (11). the composite intermediate layer (11) is formed by a support layer (12), including a plasticized PVC containing a film and a polymeric adhesive layer (13) in one, or preferably both, of the main surfaces of the support layer ( 12). The adhesive layers (13) are formed of polymeric material which is capable of adhering to the support layer containing PVC (12), and to the glass sheets (10). The respective refractive indices of the adhesive layers (13) and the support layer (12) coincide as much as possible in order to eliminate optical distortion due to reflections at the incident light interfaces. A preferred copolymer resin for forming the adhesive layers (13) is poly (vinyl) chloride-co-vinyl acetate-co-maleic acid

Description

INTERMEDIATE GLASS OF SELF ADHESIVE SAFETY GLASS OF POLYVINYL CHLORIDE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate layer for safety glass and, in particular, to a self-adhering composite intermediate layer that includes a layer containing polyvinyl chloride. 2. Compendium of the Related Art Safety glass is a well-known term for a glass sandwich composed of an intermediate layer that joins two plates or sheets of glass, so that when the glass breaks, it results in a minimum dispersion of glass. fragments of broken glass. The intermediate layer must possess a number of properties, including the following: high adsorption of impact energy to minimize striking injuries; enough shear strength to prevent broken glass from breaking the intermediate layer; sufficient adhesion to glass to inhibit laceration upon contact with, and prevent dispersion of, broken glass; acceptable thermal stability and wear resistance; and good optical quality. The intermediate layer must possess these properties over a wide temperature range, where these laminated glasses are used.

It is widely known that when a plasticized polyvinyl butyral film is used as an intermediate layer material in a safety glass for automobiles, aircraft and building materials due to its high adhesiveness, transparency and good mechanical properties over a wide range of temperatures. However, the use of plasticized polyvinyl butyral films makes the production of laminated safety glass relatively expensive. The surface of the plasticized polyvinyl butyral film is very rough, and presents the problem of blocking after the formation of the film. Accordingly, the polyvinyl butyral plastic film should be provided with some dividing device if it is to be stored or transported in the form of piles of cut sheets or in the form of rolls. In addition, the production of plasticized polyvinyl butyral films requires specialized equipment and, due to their sensitivity to moisture, plasticized polyvinyl butyral films should generally be handled under controlled atmosphere conditions during manufacture, stored immediately before incorporation. in laminated safety glass. All this adds to the cost of using laminated polyvinyl butyral films in laminated safety glass. Alternative materials have been proposed for the intermediate layers. For example, U.S. Patent No. 4,277,538 to Beckman et al. Discloses a laminated safety glass that uses a plasticized polyvinyl chloride (PVC) sheet as the intermediate layer. The use of PVC could be advantageous, in the sense that it could be produced in conventional equipment, and its manufacture could be much less expensive, and to be able to process it in a laminated safety glass when compared with the polyvinyl butyral. However, by itself, a PVC film does not adhere to the glass. To increase the adhesion of PVC to glass, Beckman and colleagues suggest the use of an organofunctional silane, either as a glue or evenly dispersed in the PVC film. However, the uses of the silane adhesion promoter have their disadvantages. It was found that dispersing an organofunctional silane in the PVC film in amounts sufficient to provide adequate adhesion to the glass results in a laminate having a mist that is unacceptably high for many applications. In addition, dispersing the silane in the intermediate layer can have a negative effect on the processability of the intermediate layer material. Second, the application of an organofunctional silane adhesion promoter necessitates an additional laminate manufacturing step, increasing the manufacturing costs of the resulting laminated glass unit.

U.S. Patent No. 4,600,627 discloses a laminated glass unit that includes a pair of glass sheets and a composite intermediate layer. The intermediate layer is formed of an intermediate sheet formed of polyester or PVC sandwiched between two intermediate layers of a crosslinking polymer, which may be ethylene / vinyl acetate (EVA.). The intermediate layers, which provide an adhesive bond between the intermediate sheet and the two glass sheets, have a thickness of approximately 0.2 mm. However, it was determined that the EVA intermediate layers do not provide sufficient adhesion to the glass, and therefore the use of the silane adhesion promoters is required. Furthermore, at least where the intermediate sheet is formed of PVC, the resulting laminated glass exhibits poor optical qualities. Accordingly, it would be advantageous to provide an improved PVC containing an intermediate layer which is relatively inexpensive and self-adhering to a glass sheet. It would also be advantageous to provide a layer containing PVC which, when incorporated into the laminated glass, provides a good optical quality. SUMMARY OF THE INVENTION The present invention relates to an improved layer containing polyvinyl chloride for laminated security glasses. The laminated safety glass or glass unit includes a pair of glass sheets bonded together with a self-adhering composite intermediate layer. The composite intermediate layer is formed of a backing layer including a plasticized PVC containing a film, and a polymeric adhesive layer in one, or preferably both, of the main surfaces of the backing layer. The adhesive layers are formed of a polymeric material which is capable of adhering to the PVC containing the support layer, and to the glass sheets. In a preferred embodiment, the adhesive layers have a first refractive index, and the backing layer has a second refractive index that matches the first refractive index, as much as possible, in order to eliminate the optical distortion caused by the reflection of the incident light in the interface. To achieve this, the first and second refractive indices should not differ by more than about 0.05. The adhesive layers are preferably formed of a copolymer of vinyl chloride, and at least one comonomer capable of adhering to the glass. A preferred copolymer resin for forming the adhesive layers in poly (vinyl chloride-co-vinyl acetate-co-maleic acid). The adhesive layers can be sprayed as latexes to form a film on the backing layer or the glass sheets. Alternatively, the formula of the adhesive layer can be placed in a solution and roller coated or printed by rotogravure as a thin film in one of the support layers. The adhesive layers can also be coextruded in the form of granules with the support layer. Gravure printing is the preferred method for forming the adhesive layers. The thickness of the adhesive layers will be determined by the degree to which the refractive index of the adhesive layer coincides with that of the backing layer, and by the desired level of adhesion. In accordance with the present invention, the thickness of each of the adhesive layers is preferably not more than 0.002 cm, and preferably not more than 0.001 cm. The improved PVC containing the intermediate layer of the present invention is thus relatively inexpensive, and is self-adhesive to a glass sheet. In addition, the intermediate layer provides a laminated glass having a good optical quality. Other objects and advantages will be more apparent during the course of the following description, when taken in relation to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWING The drawing is a diagrammatic cross-sectional view of a laminated glass unit in accordance with the present invention. DESCRIPTION OF THE PREFERRED MODALITY The numerous and diverse properties that an intermediate layer material requires to be used in laminated safety glass, has made it very difficult to successfully develop this laminated safety glass using an intermediate layer of PVC, even though the advantages of this are potentially large. As mentioned above, the properties that an intermediate layer must possess include: high absorption of impact energy; high resistance to sufficient shear forces to prevent broken glass from breaking the intermediate layer; sufficient adhesion to the glass to inhibit laceration upon contact with, and prevent dispersion of, broken glass; acceptable wear and thermal stability; and good optical quality. In accordance with the present invention, there is provided a laminated safety glass or glass unit, which includes a pair of glass sheets 10 joined together with a self-adhered composite intermediate layer 11. The composite intermediate layer 11 is formed of a layer of support 12, including a plasticized PVC containing film and a plastic adhesive layer 13 on one or both of the main surfaces of the support layer. Preferably, an adhesive layer 13 is provided on both sides of the support layer 12, as illustrated in the drawing. As will be described later, the use of the composite intermediate layer 11 results in a laminated glass having all the aforementioned properties, and whose production is more economical than a comparable laminated glass using polyvinyl butyral. SUPPORT LAYER The support layer 12 of the composite intermediate layer 11 is formed of a polyvinyl chloride polymer of a relatively high average molecular weight. Thus, the support layer 12 includes a vinyl chloride homopolymer, copolymer or graft polymer, or mixed combinations thereof. The thickness of the support layer 12 essentially affects the impact resistance of laminated glass. The impact strength of the laminated glass unit will decrease as the thickness of the support layer 12 decreases, so that a support layer 12 of at least 0.05 cm is preferred. However, from a commercial point of view, it is desirable to form a support layer, so that the overall thickness and weight of the laminated glass unit is comparable to current products, which use an intermediate PVB layer of approximately 0.07 cm thick. According to this, the thickness of the support layer 12 is preferably between 0.07 and 0.08 cm. If the intermediate layer is formed of a polyvinyl chloride homopolymer, it preferably has a mean molecular weight, or a mixture of average molecular weights of at least 30,000. In a preferred embodiment, the average molecular weight, or mixture of average molecular weights, is between about 40,000 and 165,000, with a degree of polymerization of between 500 to 2,600. A preferred PVC resin of this type is SE-1300, with a degree of polymerization of 1,300 and an average molecular weight of 80,600, which is commercially available from Shintech Inc. of Houston, Texas, United States. The control of the molecular weight distribution and the purity of the PVC were revealed as extremely important in a safety glass interlayer application. The variances and the molecular weight distribution can have a profound effect on the impact and processability properties of the film. In addition, the presence of impurities, such as initiators, can lead to excessive degradation of the intermediate layer, and that it acquires a yellowish color, and can have a long-term detrimental effect on the thermal stability of the intermediate layer. Accordingly, PVC is preferably formed by a suspension polymerization, which offers superior control of molecular weight and the removal of impurities. It was also discovered that a plasticized film containing a mixture of PVC homopolymer with copolymers, such as a copolymer between vinyl chloride and vinyl acetate, provides an improved intermediate layer. This copolymer showed better flow properties, and therefore, when mixed as PVC homopolymer results in a better processability over the PVC homopolymer alone. The support layer 12 is composed of a mixture of between about 75 to 98 phr PVC, and about 2 to 25 phr poly (vinyl chloride-co-vinyl acetate). In a preferred embodiment, the mixture is about 95 parts of PVC homopolymer, and about 5 parts of the poly (vinyl chloride-co-vinyl acetate). Examples of suitable vinyl chloride / vinyl acetate copolymers are MPR-TSN, commercially available from Nissin Chemicals, Nitta-Gun, Japan, which is a copolymer of 87% vinyl chloride and 13% vinyl acetate with a polymerization degree of 400; and UCAR VYHD, commercially available from Union Carbide, which is a copolymer of 86% vinyl chloride and 14% vinyl acetate with a degree of polymerization of 220. In another preferred embodiment, the support layer 12 is formed of a mixture of PVC homopolymer and a copolymer of vinyl chloride and methacrylate. An example of a suitable vinyl chloride / methacrylate copolymer is Geon E8, commercially available from The Geon Company. In this embodiment, the support layer 12 is formed from between about 40 to 80 parts of PVC homopolymer with about 20 to 60 parts of the vinyl chloride / methacrylate copolymer. This mixture also preferably includes from about 5 to 15 parts of a polycaprolactone, such as CAPA 656, commercially available from Solvay Interox. In another preferred embodiment, the support layer 12 is formed of an ethylene / vinyl chloride copolymer. A suitable example of this is VE-U resin, commercially available from Sekisui of Japan. This poly (vinyl chloride-co-ethylene) includes an 8% ethylene comonomer, and has a degree of polymerization of 1.050. In the most preferred embodiment, the support layer 12 is formed of a vinyl chloride copolymer or a mixture of vinyl chloride and one or more vinyl monomers copolymerizable therewith, and an allylic ether prepared by the partial allylation of an alcohol polyhydric, or a mixture of these allylic ethers, as described more fully in the co-pending application, with Serial No. 08 / 283,386, entitled "VINYL CHLORIDE COPOLYMERS AND METHOD FOR PRODUCING THEM". The level of vinyl chloride should be maintained above 50% by the weight of the total monomer mixture. Examples of hydroxy-containing monomers synthesized by the partial allylation of these polyhydric alcohols include diallyltrimethylolpropane ether, monoallytrimethylolpropane ether, allylic sucrose, allyl pentaerythritol, glyceryl monoallyl ether, glycerol diallyl ether, etc. The preferred hydroxy-containing monomer is trimethylolpropane monoallyl ether and trimethylolpropane diallyl ether. The allylic ethers prepared by the partial allylation of the polyhydric alcohols are preferably used according to the invention in the range of 0.015 to 30, and more preferably in the range of between about 0.1 to 10, parts by weight per hundred parts of the weight of the total monomer mixture. The plasticizers for the preparation of plasticized films containing PVC according to the present invention may be linear or branched aliphatic diesters, triesters or tetraesters, or aromatic diesters, triesters or tetraesters, or mixtures thereof. From an efficiency standpoint, preferred plasticizers include dihexyl azelate (DHZ), dihexyl adipate (DHA) and dioctyl azelate (DOZ). However, dioctyl adipate (DOA), while providing slightly reduced efficiency relative to the other annotated plasticizers, may be most preferable in view of its combination of efficiency and relatively lower cost. In addition, plasticizer mixes can be used for both economic and efficiency considerations. For example, mixing benzylbutyl phthalate (BBP) or DOP with DHA will result in a higher glass transition temperature with DHA alone, and at the same total plasticizer level. As a result, the average breaking height at room temperature will improve without disturbing the efficiency at low temperature. The total plasticizer concentration is between about 20 to 60 phr, depending mainly on the number of the average molecular weight and the molecular weight distribution of the PVC-containing resin. Most preferred is a total plasticizer concentration of between 35 and about 45 phr. Preferably, a film containing PVC with between about 1 to 5 is provided, and preferably from 2 to 4 phr, of a primary heat stabilizer including an organometallic compound, such as salts of the alkali metals and selected transition metals, including aluminum, barium, cadmium, calcium, lead, magnesium, tin and zinc. The primary heat stabilizer preferably includes a mixture of a zinc salt of an organic acid and a barium, calcium or tin salt of an organic acid, or a mixture of these. The primary heat stabilizer preferably includes from about 1.6 to 4.0% atomic zinc as the zinc salt of an organic acid, and from about 7.0 to 14.0% atomic barium as the barium salt of an organic acid. The zinc salt can be, for example, zinc stearate, zinc laurate, zinc oleate, zinc isostearate, zinc octoate or zinc decanate, or mixtures thereof. Similarly, examples of suitable barium and calcium salts include barium or calcium stearate, laureate, oleate, isostearate, octane, decanate or nonylphenolate, or mixtures thereof. To maximize the maximum duration, the thermal stability of the service use of the PVC providing used as an intermediate layer of safety glass, the primary heat stabilizer also preferably includes from about 2.0 to 4.0% phosphorus as phosphites. It was found that a preferred phosphite is triphenyl phosphite. In addition to the primary heat stabilizer, the PVC-containing film also preferably includes various secondary heat stabilizers, including epoxidized oils, perchlorates, and 1,3-beta-diketones. From about 2.5 to 15.0 phr of a preferred epoxidized oil is included as the second heat stabilizer in the PVC-containing film. A preferred epoxidized oil is epoxidized soybean oil. The PVC film also preferably includes from about 0.1 to 1.0 phr of a perchlorate, where a preferred perchlorate is sodium perchlorate. As another secondary heat stabilizer, the PVC film is provided with between about 0.1 to 2.0 phr of 1,3-beta-diketone. A preferred 1, 3 [beta] -dicetone is benzoylstearyl methane. The support layer 12 may also include other additives, such as UV light stabilizers, antioxidants, optical brighteners, dyes and the like. Accordingly, the support layer 12 is preferably formed of a formula that includes between about 0 to 2 phr of a benzophenone or benzotriazole derivative as a UV stabilizerbetween about 0 to 5 phr of phenols as an anti-oxidant, about 0 to 1 phr of a fluorescent whitening agent, and about 0 to 1 phr of blue dye.

ADHESIVE LAYERS The adhesive layers 13 of the intermediate layer 11 are formed of a polymeric material that adheres to both the backing layer 12 and the glass sheets 10. If an adhesive layer 13 is provided on each of the surfaces of the backing layer. 12, the two adhesive layers 13 can be of the same or different formulas. For example, where the laminated glass unit must be mounted on a vehicle, it may preferably form the adhesive layers 13 with different formulas resulting in different levels of adhesion to the glass sheets 10. Therefore, it may be preferable to formulate the adhesive layers 13 so that there is a higher level of adhesion between the support layer 12 and the glass sheet 10 that is inside the vehicle between the support layer 12 and the glass sheet 10 that is on the outside of the vehicle. As noted above, the adhesive layers 13 should adhere to the backing layer 12, as well as the glass sheets 10. To accomplish this, the adhesive layers 13 are formed of a polymeric material that is thermodynamically compatible with the backing polymer. vinyl chloride of the support layer 12, and h includes at least one type of functional group that is capable of forming chemical bonds with the glass, where these bonds can be covalent, ionic, hydrogen bonds, and other chemical bonds. The adhesive layers 13 are preferably formed of a copolymer having a functional group that is capable of adhering to the support layer. As used herein, the term "copolymer" means a polymer formed by the polymerization of two or more different types of monomer species. Examples of preferred polymers for forming the adhesive layers 13 include poly (ethylene-co-vinyl acetate-co-acrylic acid); poly (vinylpyrrolidone-co-vinyl acetate); poly (vinyl chloride-co-vinyl acetate-co-vinylalcohol); poly (vinyl chloride-co-acrylic ester); poly (vinyl chloride-co-vinyl acetate-co-maleic acid); poly (vinyl chloride-co-acrylic ester-co-maleic acid); and copolymers of vinyl chloride, vinyl acetate or acrylic ester, and the acid of the acrylic ester. Since the backing layer 12 is formed of a vinyl chloride homopolymer, copolymer, graft polymer, or combination thereof, the vinyl chloride groups present in the above examples provide excellent adhesion to the backing layer 12 by an entangled intermolecular chain mechanism, as occurs in thermodynamically compatible polymers. The vinyl acetate groups and other groups h are compatible with the vinyl chloride also provide adhesion to the support layer 12. The acid functionality provided in the above examples by the maleic acid or the acid of an acrylic ester is a preferred form of obtaining adhesion of the adhesive layer 13 to the glass sheets 10. In a preferred embodiment, the formula of the adhesive layers 13 may include a silane, preferably a silane h can react covalently with the polymer in the adhesive layers 13 for forming a graft copolymer. It is thought to form this graft copolymer. it will prevent the diffusion of the silane towards the support layer 12, and consequently reducing adhesion. Epoxy, mercapto and aminosilanes are preferred. If the adhesive layers 13 contain acid groups, an epoxysilane, such as the glycidoxypropyltrimethoxysilane range, is preferred. The functional acid groups of the polymer can then be used to react with the epoxy, forming a graft copolymer with characteristic alkoxysilane groups, h can be hydrolyzed, and in turn attached to the glass sheet 10. In this way, an excellent adhesion with low sensitivity to moisture between the adhesive layer 13 and the glass sheet 10, even when the adhesive layer 13 is deposited to a thickness of less than 0.0002 cm on the surface of the support layer 12. Also, include a silane in the adhesive layers 13 it did not result in significant fog in the laminated glass. Adhesive layers 13 preferably include a plasticizer comprising a diester, linear or branched aliphatic tetraester or triester, or diester, triester or aromatic tetraester, or mixtures thereof, where the concentration of the plasticizer is between about 5 and 60 phr. The adhesive layers 13 are preferably provided between about 1 to 5, preferably 2 to 4 phr, of a heat stabilizer including an organometallic compound, such as the salts of the selected alkali metals and transition metals, including aluminum, barium , cadmium, calcium, lead, magnesium, tin and zinc. For the adhesive layers 13, the heat stabilizer preferably includes a tin salt of an organic acid. Adhesive layers 13 may also contain other heat stabilizers, such as those noted above for backing layer 12. Adhesive layers 13 may also include other additives, such as UV light stabilizers, antioxidants, optical brighteners, dyes, fillers inorganic, inorganic pigments and the like. The adhesive layers 13 of the present invention are preferably formed from a formula including up to about 10 phr of a benzophenone or benzotriazole derivative as a UV stabilizer. Adhesive layers 13 may also include up to about 5 phr of phenols as an antioxidant, up to about 1 phr of a bleach or fluorescer, and up to about 1 phr of blue dye. The adhesive layers 13 are preferably formed as thin films on the surfaces of the support layer 12, or the respective glass sheets 10. Each adhesive layer 13 is approximately 0.0002 to 0.1 cm thick. Within that range, the thicker adhesive layer 13 will provide greater adhesion to the intermediate layer 11 and the glass sheets 10. At the upper end of that range, the copolymers discussed above will provide sufficient adhesion between the backing layer 12 and the backing layers 12. glass sheets 10. However, some of these copolymers have a refractive index that is different from the refractive index of the backing layer 12. This difference in the refractive index may be large enough to cause visible reflections from the interface between the support and adhesive layers. These reflections result in optical distortion, especially since the support layer 12 is generally provided with an embedding pattern to facilitate ventilation during lamination. Therefore, from the point of view of the optical quality, it is preferred to form the adhesive layers 13 as thin as possible. This is especially so if the silane is included in the adhesive layer 13. However, as the thickness of the adhesive layers 13 is reduced, the levels of adhesion to the glass will also decrease. In this way, the minimally tolerable thickness to retain the desired adhesion can produce an optical distortion problem if there is a significant difference in the refractive indices of the backing layer 12 and the adhesive layers 13.

As a result, in order to provide the most advantageous combination of adhesion and optical quality, it is important to match as closely as possible the refractive index of the adhesive layers 13 to the refractive index of the backing layer 12. The respective refractive indexes should not differ. of more than about 0.05, preferably not more than 0.04, and more preferably not more than 0.03, and even not more than about 0.01. The thicker the adhesive layers 13 are, the refractive indexes must match more. To achieve this, it is preferred to form the adhesive layers 13 of a copolymer including vinyl chloride. Thus, the adhesive layers 13 are preferably formed of a copolymer of vinyl chloride and a co -omer capable of adhering to the glass. A more preferred resin for forming the adhesive layers 13 is poly (vinyl chloride-co-vinyl acetate-co-maleic acid), such as the VMCH commercially available from Union Carbide. The refractive index of the adhesive layers 13 must be adjusted by altering the additives included in the formula. For example, since the BBP has a refractive index higher than DHA, the refractive index of the adhesive layers 13 must be increased by using BBP as a plasticizer, reduced by using DHA as a plasticizer, or controlled by using a mixture of BBP / DHA As mentioned above, the adhesive layers 13 can be applied to the glass sheets 10 or the backing layer 12. The adhesive layers 13 can be applied by any suitable technique. For example, the adhesive layers 13 can be sprayed as a latex to form a film and a backing layer 12 or the glass sheets 10. Alternatively, the formula of the adhesive layer 13 can be placed in solution and be roller coated or printed as rotogravure as thin film in the backing layer 12. The adhesive layers 13 can also be coextruded in the form of granules with the backing layer 12. The rotogravure printing is the preferred method for forming the adhesive layers 13. EXAMPLES The following points are illustrative of the present invention, and do not constitute any limitation with respect to the subject matter of the present invention. The adhesion, optical quality, refractive index, and thermal stability of each of the laminates in these examples were measured in the following methods. 1. Adhesion The piston method was used to measure the adhesion of the intermediate layer to the glass. 12-inch square glass laminates were placed in a refrigerator at 18 ° C for at least two hours. After being removed from the refrigerator, the laminates were placed on a metal substrate and repeatedly struck with a 16-ounce hammer to break the glass. Then all the broken glass not adhering to the intermediate layer was removed. The amount of glass adhering to the intermediate layer was visually compared to a set of known piston scale standards, and a piston value was assigned for each sample, varying from a piston value of 0 (no addition, no glass). adhered) to 10 (high adhesion, 1005 of adhering glass). 2. Optical Quality The optical quality of the laminated samples was determined by measuring distortion transmitted using a floating glass distortion meter, and by visual inspection using both a cross-linked background and a shadow meter. The transmitted shadows were measured with a Hazegard XL200 from Gardner / BYK. 3. Refraction index The refractive index was measured using the Becke-Line method. . Thermal Stability Thermal stability was determined by controlling the rate at which laminated samples of four square inches acquired a yellowish color in one or more temperature controlled furnaces. After measuring the initial yellow index (YIC) using Gardner's Spectrogard / BYK Silver Springs, Maryland, the samples were placed in one of five ovens placed at various temperatures (65, 80, 100, 120 and 150 ° C). The samples were removed from the ovens at regular intervals and the YIC was measured. The various interval times were as follows: 500 hours for the oven to 65 ° C, 250 hours for the oven at 80 ° C, 48 hours for the oven at 100 ° C, 24 hours for the oven at .120 ° C, and 4 hours for the oven at 150 ° C. 5. Boiling Test Adhesion, YIC and Mists were also measured after the samples were subjected to a boil test. In the boiling test, the samples were subjected vertically on the edge, in water at 66 ° C for 3 minutes, and then rapidly transferred and similarly immersed in boiling water. The samples were kept in boiling water for 2 hours and then removed. EXAMPLE 1 A support layer of approximately 0.01 cm was made with the following formula: Component phr Resin SE1300 PVC1 90 Geon E82 5 CAPA 6563 5 Adheto dihexyl 50 BBP 5 Drapex 6.84 5 Ther chek 13? ') 3 Irganox 10106 0.5 CPL46 0.1 Tinuvin 3288 0.2 1. PVC resin having a degree of polymerization of 1300 available from Shintech Inc. of Freeport, TX. 2. Copolymer resin (mixture of 94% vinyl chloride - 6% methyl acrylate monomer) available from The Geon Company. 3. Polycaprolactone resin available from Solvay Interox. 4. Epoxidized soybean oil available from Witco Corp. of Oakland, NJ. 5. Barium / zinc stabilizer package available from Ferro Corp. of Alton Hills, OH. 6. Phenolic antioxidant available from Ciba-Geigy Corp. of Hawthorne, NY. 7. Perchlorate stabilizer available from Asahi Denka Kogyo K.K. from Japan. 8. Benzatriazole ultraviolet light stabilizer available from Ciba-Geigy Corp. Adhesive layers were formed by applying a layer of poly (ethylene-co-vinyl acetate-co-acrylic acid) latex to the backing layer. The intermediate layer was then dried for 15 minutes at 100 ° C. A 2% aminosilane solution was applied to the glass sheets, and the laminates were assembled and autoclaved at 340 ° F and 240 psi with a retention time of 25 minutes. Transparent laminates were obtained with the following results: Property Value Adhesion, initial (piston) 9 Fog, initial 1.0% refractive index Approx. 1.47 Adhesive layers approx. 1.53 Support layer Optical quality visible distortion the incrustation in the support layer. EXAMPLE 2 A support layer of approximately .08 thickness was made with the following formula. Component phr Resin SE1300 PVC 70 Geon E8 20 LAYER 656 10 Dihexyl Adipate 40 Drapex 6.8 5 Thermchek 130 3 Irganox 1010 0.5 CPL46 0.1 Tinuvin 328 0.25 An adhesive layer was then applied to both surfaces of the support layer. These adhesive layers were applied by rotogravure printing on the support layer with a solution of the following formula: Component Weight% VMCH9 19.1% Dihexyl Adipate 3.8% Z604010 9.5% Tinuvin P 0.57% Thermchek 84012 0.23% Solvent MEK13 66.8% 9. Poly (vinyl chloride-co-vinyl acetate-co-maleic acid) with an average molecule weight number of 20,000, available from Union Carbide Corp. 10. Gamma glycidoxypropyltrimethoxysilane available from Dow Corning. 11. Benzotriazole ultraviolet light stabilizer available from Ciba-Geigy Corp. 12. Tin stabilizer available from Ferro Corp. 13. Methyl ethyl ketone After allowing the solvent to evaporate, the use of each of the adhesive layers was determined, by weight, and they were approximately 0.0001. "The laminates were assembled with a pair of 12" x 12"glass sheets, and the intermediate layer previously described, and were autoclaved at 300 ° F and 240 psi with a time Retention time of 25 minutes Transparent laminates were obtained with the following results: Property Value Adhesion, initial (piston) 9 Fog, initial 0.5-0.8% Initial YIC 0.5 Adhesion after boiling test No change Fog by boiling test No change YIC after boiling test No change Refraction index Adhesive layers 1.521 + .001 Support layer 1.546 + .003 Thermal stability * 5.6 Optical quality No visible distortion * YIC then d e 500 hours at 100 ° C. For comparison, samples were laminated with the identical support layer but without the adhesive layer under the identical autoclave cycle after applying a 4% gamma mercaptopropyltriethoxysilane solution on each glass sheet. For these samples, the YIC after 500 hours at 100 ° C was determined as 6.4.

EXAMPLE 3 Laminates were made that were identical to those made in Example 2, except that the adhesive layers included 3.8% by weight of BBP instead of 3.8% by weight of DHA. The refractive indexes were measured in the following way: Refraction index Support layer 1.546 + .003 Adhesive layer with DHA 1.521 + .001 Adhesive layer with BBP 1.535 + .001 EXAMPLE 4 A support layer approximately 0.08 cm thick was made with the following formula: Component phr Resin SE1300 PVC 90 Geon E8 5 CAPA 656 5 DHA 42.5 BBP 5 Drapex 6.8 5 Thermchek 130 3 Irganox 1010 0.5 CPL46 0.1 Tinuvin 328 0.2 This support layer was provided with an adhesive layer on both surfaces by rotogravure printing with each of the following formulas, which vary only with respect to the level of epoxysilane included. Component # 1 (weight%) # 2 (weight%) # 3 (weight%) VMCH 19.1% 19.1% 19.1% Dihexyl Adipate 3.8% 3.8% 3.8% Z6040 9.5% 5.0% 1.0% Tinuvin P 0.57%% 0.57% 0.57 % Ther chek 840 0.23%% 0.23% 0.23% Solvent MEK '66.8% 66.8% 66.8% After allowing the solvent to evaporate, the thickness of each of the adhesive layers was determined by weighing them. They were assembled into laminates with a pair of 12"x 12" glass sheets, and the intermediate layer described above, and were autoclaved at 300 ° F and 240 psi with a retention time of 25 minutes. Transparent laminates were obtained with the following results: Weight% Silane Thickness Adhesion (piston) # 1 9.5 0.088 thousand 9 # 2a 5.0 0.073 thousand 9 # 2b 5.0 0.051 thousand 2 # 3 1.0 0.074 thousand 1

Claims

1. A laminated glass unit, comprising sequentially: a first sheet of glass; an adhesive layer including a polymeric material, wherein the adhesive layer has a first refractive index; a support layer including a plasticized vinyl chloride polymer, wherein the support layer has a second refractive index; and a second sheet of glass; where the first and second refractive indices differ by no more than about 0.05.

2. A laminated glass unit as defined in claim 1, wherein the first and second refractive indices differ by no more than about 0.04.

3. A laminated glass unit as defined in claim 1, wherein the first and second refractive indices differ by no more than about 0.03.

4. A laminated glass unit as defined in claim 1, wherein the first and second refractive indices differ by no more than about 0.01. A laminated glass unit as defined in claim 1, further including a second adhesive layer including a polymeric material interposed between the support layer and the second glass sheet, wherein the second adhesive layer has a refractive index which differs from the second refractive index by no more than about 0.0

5.

6. A laminated glass unit as defined in claim 1, wherein the adhesive layer includes vinyl chloride polymer.

7. A laminated glass unit as defined in claim 6, wherein the adhesive layer includes a vinyl chloride copolymer and a comonomer having acid functional groups.

8. A laminated glass unit as defined in claim 6, wherein the adhesive layer includes a copolymer of vinyl chloride, vinyl acetate and maleic acid.

9. A laminated glass unit as defined in claim 6, wherein the adhesive layer includes a copolymer of vinyl chloride, vinyl acetate and vinyl alcohol.

10. A laminated glass unit as defined in claim 1, wherein the support layer includes a copolymer of vinyl chloride and methyl acrylate.

11. A laminated glass unit as defined in claim 1, wherein the support layer includes a copolymer of vinyl chloride and an allylic ether prepared by the partial allylation of a polyhydric alcohol.

12. A laminated glass unit as defined in claim 1, wherein the support layer includes a copolymer of vinyl chloride and ethylene.

13. A laminated glass unit as defined in claim 1, wherein the adhesive layer includes a silane.

14. A laminated glass unit as defined in claim 12, wherein the silane is an epoxy silane.

15. A laminated glass unit as defined in claim 12, wherein the silane is an aminosilane.

16. A laminated glass unit as defined in claim 12, wherein the silane is a mercaptosilane.

17. A laminated glass unit as defined in claim 1, wherein the adhesive layer is not more than 0.001 cm thick, and where the support layer is at least 0.002 cm thick.

18. A laminated glass unit as defined in claim 12, wherein the support layer is at least 0.6 cm thick.

19. A laminated glass unit, comprising sequentially: a first sheet of glass; a support layer including a vinyl chloride polymer; an adhesive layer including a polymeric material that is thermodynamically compatible with the vinyl chloride polymer, wherein the polymeric material includes at least one type of functional group that is capable of forming chemical bonds with the glass; and a second sheet of glass.

20. A laminated glass unit as defined in claim 19, further including a second adhesive layer interposed between the support layer and the first glass sheet, wherein the second adhesive layer includes a polymeric material that is thermodynamically compatible with the vinyl chloride polymer, wherein the polymeric material includes at least one type of functional group that is capable of forming chemical bonds with the glass.

21. A laminated glass unit as defined in claim 19, wherein the adhesive layer includes a vinyl chloride polymer.

22. A laminated glass unit as defined in claim 21, wherein the adhesive layer includes a vinyl chloride copolymer and a comonomer having acid functional groups.

23. A laminated glass unit as defined in claim 21, wherein the adhesive layer includes a copolymer of vinyl chloride, vinyl acetate and maleic acid. 2 . A laminated glass unit as defined in claim 21, wherein the adhesive layer includes a copolymer of vinyl chloride, vinyl acetate and vinyl alcohol. 25. A laminated glass unit as defined in claim 19, wherein the support layer includes a copolymer of vinyl chloride and ethylene. 26. A laminated glass unit as defined in claim 19, wherein the support layer includes a copolymer of vinyl chloride and methyl acrylate. 27. A laminated glass unit as defined in claim 19, wherein the support layer includes a copolymer of vinyl chloride and an allylic ether prepared by the partial allylation of a polyhydric alcohol. 28. A laminated glass unit as defined in claim 19, wherein the adhesive layer includes a silane. 29. A laminated glass unit as defined in claim 28, wherein the silane is an epoxysilane. 30. A laminated glass unit as defined in claim 28, wherein the silane is an aminosilane. 31. A laminated glass unit as defined in claim 28, wherein the silane is a mercaptosilane. 32. A laminated glass unit as defined in claim 19, wherein the adhesive layer is not more than 0.001 cm thick, and where the support layer is at least 0.02.c thick. 33. A laminated glass unit as defined in claim 32, wherein the support layer is at least 0.06 cm thick. 34. A method for forming a self-adhering interlayer for a laminated glass unit, comprising the steps of: a support layer including a plasticized vinyl chloride polymer; applying an adhesive layer to at least one surface of the support layer, wherein the adhesive layer includes a polymeric material that is thermodynamically compatible with the vinyl chloride polymer, wherein the polymeric material includes at least one type of functional group that is capable of to form chemical bonds with glass. 35. A method as defined in claim 34, wherein the adhesive layer placed in solution and applied to the backing layer by rotogravure printing.