MX2008006814A - Polymer interlayers comprising ethylene-vinyl acetate copolymer - Google Patents

Abstract

The present invention is in the field of polymer interlayers used in multiple layer glass panels, and specifically the present invention is in the field of polymer interlayers comprising a polymer sheet comprising an ethylene-vinyl acetate copolymer.

Description

POLYMERIC INTERMEDIATE LAYERS THAT COMPRISE COPOLYMER OF ETHYLENE-VINYL ACETATE FIELD OF THE INVENTION The present invention is in the field of polymeric intermediate layers in multilayer glass panels, and specifically the present invention is in the field of polymeric intermediate layers comprising a layer of ethylene-vinyl acetate copolymer.

BACKGROUND OF THE INVENTION Polymeric sheets which can be used as intermediate layers in multi-layered laminate products, light transmitters, such as safety glass or polymeric laminated products, typically comprise (poly) vinyl butyral. Security glass generally refers to a transparent layered product comprising a (poly) vinyl butyral sheet, disposed between two sheets of glass. Safety glass is often used to provide a transparent barrier in architectural and automotive openings. Its main function is to absorb energy, such as that caused by the impact of an object, without allowing penetration into the opening.

Although poly (vinyl) butyral is generally suitable for use as a polymeric sheet in intermediate security glass layers, alternative materials are often also useful. For example, both ionomeric polymer and polyurethane have been used in glass laminates. Intermediate layer materials are chosen, among other reasons, for improved handling, reduced production cost and improved performance. Alternative alternatives to the intermediate poly (vinyl) butyral layers may be useful, if those alternatives show improved performance or are less expensive to manufacture. A particularly useful polymer is the ethylene-vinyl acetate or EVA copolymer. Before use in intermediate glass layers, the ethylene-vinyl acetate copolymer is typically modified so as to impart the desired transparency and performance characteristics (see, for example, U.S. Patent 5,415,909). Modifications to the ethylene-vinyl acetate copolymer that improve transfer include the use of monosubstituted benzaldehyde and the use of thermosetting compounds (see, for example, U.S. Patents 5,352,530 and 4,935,470). These modifications may, however, result in less than ideal thermostability in the finished stratified product. Accordingly, further improved materials of ethylene-vinyl acetate copolymer are needed in the art for use in an intermediate layer or part of an intermediate layer in multi-layered glass panels.

BRIEF DESCRIPTION OF THE INVENTION It has now surprisingly been discovered, in accordance with the present invention, that the intermediate layers comprising ethylene-vinyl acetate copolymer incorporating a reaction product of a disubstituted benzaldehyde and a polyhydric alcohol or polyhydric alcohol derivative have excellent transparency and thermostability .

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 represents a schematic cross-sectional view of an embodiment of an intermediate layer of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to intermediate layers that can be used in multilayer laminated glass constructions, such as those used in architectural applications and automotive windshield applications. The layers of the present invention incorporate one or more layers of ethylene vinyl acetate copolymer, wherein the ethylene vinyl acetate copolymer layer comprises an ethylene vinyl acetate copolymer incorporating the reaction product of an alcohol. polyhydric or polyhydric alcohol derivative and one or more disubstituted benzaldehydes, as will be described in detail below. As used herein, "polyhydric alcohol / modified EVA with disubstituted benzaldehyde" means ethylene vinyl acetate copolymer comprising, as an added agent, the reaction product of a polyhydric alcohol or polyhydric alcohol derivative and a disubstituted benzaldehyde, as will be described in detail below. In - various embodiments of the present invention, an intermediate layer comprises a polymeric sheet comprising polyhydric alcohol / EVA modified with disubstituted benzaldehyde. In various embodiments of the present invention, an intermediate layer consists of or consists essentially of a polymer sheet of polyhydric alcohol / EVA modified with disubstituted benzaldehyde. Intermediate layers of the present invention also include multilayer intermediate layers that are formed by laminating a polymer sheet comprising polyhydric alcohol / modified EVA with disubstituted benzaldehyde with one or more additional polymeric layers, as is well known in the art. For example, one or more conventional polymeric sheets, as described in detail below, can be positioned in contact with the polymer sheet comprising polyhydric alcohol / modified EVA with disubstituted benzaldehyde to form a stacking and the stacking can then be stratified to form a intermediate layer. In addition, one or more polymeric films, as described with detail later, can be incorporated in intermediate layers of several layers. Examples of intermediate multilayer constructions of the present invention include, without limitation, the five constructions given below. In which "polyhydric alcohol / modified EVA with disubstituted benzaldehyde" is abbreviated "Modified EVA": polymeric sheet // modified EVA // modified EVA polymer sheet / modified EVA modified EVA // polymer film // modified EVA polymer sheet // polymer film // modified EVA modified EVA // polymeric sheet // modified EVA and variations thereof, including multiple, in which several occurrences of a layer type may have the same composition or different composition. In various embodiments of the present invention, an intermediate layer comprises a polymeric sheet produced by coextrusion or extrusion coating, wherein the intermediate layer has more than one polymeric sheet comprising, consists of or consists essentially of polyhydric alcohol / EVA modified with benzaldehyde disubstituted In general, for any embodiment of the present invention, in which a polymeric sheet comprising polyhydric alcohol / modified EVA with disubstituted benzaldehyde is laminated with one or more additional polymeric sheets to form a layered intermediate layer multilayer product, there is a equivalent in which polymeric sheets are formed in a single intermediate layer by coextrusion or extrusion coating, as is known in the art, to form an intermediate layer comprising at least one polymeric sheet comprising polyhydric alcohol / modified EVA benzaldehyde disubstituted . An example of constructed intermediate layer mode is generally shown in FIG. 1 with 10. As shown in FIG. 1, an intermediate layer 10 that has been produced by a coextrusion or extrusion coating process comprises a first polymeric sheet 12 which comprises polyhydric alcohol / EVA modified with bifunctional benzaldehyde, a second polymeric layer 14 comprising a second polymeric material and a third polymeric sheet 16 comprising a third polymeric material. The three polymeric sheets shown in FIG. 1 correspond to a layered intermediate layer having a polymeric sheet comprising polyhydric alcohol / EVA modified with disubstituted benzaldehyde, disposed between two other polymeric sheets. In one embodiment, for example, a modality constructed in accordance with Figure 1 comprises a polymer sheet of polyhydric alcohol / EVA modified with disubstituted benzaldehyde, disposed between two polyurethane polymer sheets. In various embodiments of the present invention, the intermediate layers are formed as shown in Figure 1, with inverted layers, in that a polymeric sheet is disposed between two polymer sheets of polyhydric alcohol / modified EVA with disubstituted benzaldehyde. In further embodiments of the present invention, a polymeric sheet comprising polyhydric alcohol / modified EVA with disubstituted benzaldehyde is used to form a double layer. The double layers of the present invention comprise at least one layer of polyhydric alcohol / EVA modified with disubstituted benzaldehyde and a polymeric sheet or adjacent polymeric film, with the polymer layers disposed on a rigid substrate, for example glass or plastic. In various embodiments of the present invention-for example those in which coextrusion or extrusion coating processes are not used-a pre-laminating step is included, in which two or more polymeric sheets or polymer films are placed in contact with each other. another in the desired configuration and heat and / or pressure is applied to "adhere" the layers together enough to allow the handling of the layer as a single unit. Stratified layering or rolling or stacking can be used immediately for use in stratification procedures.

Polyvinyl alcohol / ethylene-vinyl acetate copolymer modified with disubstituted benzaldehyde As used herein, "EVA" refers to ethylene-vinyl acetate copolymer.

In various embodiments of the present invention, the ethylene-vinyl acetate copolymer resins of the present invention comprise, by weight per weight basis, 40-95 percent by weight 60-92 percent by weight or 65-85 percent by weight. cent in weight: the remainder being all or substantially all of the following vinyl acetate component: The EVA can be prepared by any conventional method, as is known in the art, including, but not limited to, the high pressure method and the emulsification method. To the resin component of the EVA described above is added a reaction product of a polyhydric alcohol or a polyhydric alcohol derivative and a disubstituted benzaldehyde in a sufficient amount to improve the transparency of the finished polymer sheet. In various embodiments, the reaction product of a polyhydric alcohol or a polyhydric alcohol derivative and a benzaldehyde substituted for the resin is added in an amount of 0.01 to 5 phr, 0.05 to 3 phr, or 0.05 to 1 phr, in where "phr" means "parts per cent resin", on a weight basis. The polyhydric alcohol and the polyhydric alcohol derivatives of the present invention include, for example and without limitation, pentaerythritol, mannitol, sorbitol, dipentaerythritol, and mixtures thereof. In a preferred embodiment, the polyhydric alcohol is sorbitol. The disubstituted benzaldehydes of the present invention include those having the general formula: wherein Ri and R2 are the same or different, and are selected from the group consisting of cyclic alkyls and alkyls having from 1 to 10 carbon atoms, NO2, CN, COOH, C1, F, Br and the like. Specific examples of disubstituted benzaldehydes include 3,4-dimethylbenzaldehyde; 3,4-dimethylbenzaldehyde; 3,4-dibutylbenzaldehyde; 3,4-dihexylbenzaldehyde; 3-chloro-4-methylbenzaldehyde, and the like.

In various embodiments of the present invention, the reaction product of a polyhydric alcohol or polyhydric alcohol derivative and a disubstituted benzaldehyde is 1,3: 2,4-bis (3,4'-d, methylbenzylidene) sorbitol, which is obtainable as Millad® 3988 from Milliken Chemical (Spartanburg, South Carolina). Other compounds that are useful with the present invention as modifiers for improving the transparency of EVA are traditional nucleating agents; for example, aromatic carboxylic acid salts (for example sodium benzoate), organophosphate salts and phosphate esters, salt of norboncarboxylic acid, sulfonamide (for example p-tallowoluenesulfonamide), esters of carboxylic acid (for example PEG 600 Dilaurate) , salts of carboxylic acid and the like. It has also been found that talc and other inorganic fillers with very small particle size have a nucleating effect. In various embodiments, the polymer sheet of ethylene-vinyl acetate copolymer has a thickness of at least 0.02 millimeters, 0.1 millimeters, 0.2 millimeters, 0.05 millimeters, 1.0 millimeters, 5.0 millimeters, 10 millimeters, 15 millimeters or at least 20 mm. The polymers of polyhydric alcohol / EVA modified with disubstituted benzaldehyde of the present invention may further include any conventional performance enhancing agents, including, but not limited to, adhesion promoters and UV stabilizers.

Polymeric Sheet As used herein, "polymeric sheet" means any thermoplastic polymer composition formed by any suitable method with a thin layer for use in combination with a modified polyhydric alcohol / EVA layer with disubstituted benzaldehyde to form an intermediate layer that provides adequate penetration and retention properties of glass to stratified glass panels. Plasticized de (poly) vinyl butyral is most commonly used to form polymer sheets. As described in this section, the "polymeric sheets" do not specifically include polyhydric alcohol / modified EVA with disubstituted benzaldehyde, which are described above. The descriptions in this section for polymeric sheets apply to coextruded or extrusion coating modalities that correspond to polymeric sheets in stratified embodiments. The following section describes the various materials that can be used to form polymeric sheets, for example those shown as elements 14 and 16 in Figure 1. In various embodiments of the present invention, the polymeric sheets can be between 0.01 and 3.0 millimeters, from 0.1 to 2.0 millimeters, from 0.25 to 1.0 millimeters, or from 0.3 to 0.7 millimeters in thickness. The polymeric sheets of the present invention may comprise any suitable polymer and, in one embodiment, as exemplified above, the polymeric sheet comprises (poly) vinyl butyral.

In any of the embodiments of the present invention given herein that comprise (poly) vinyl butyral as the polymeric component of the polymeric sheet, another embodiment is included in which the polymeric component consists of or consists essentially of (poly) vinyl butyral . In these embodiments, any of the variations of additives, including plasticizers, discussed herein, can be used with the polymeric sheet having a polymer consisting of or consisting essentially of (poly) vinyl butyral. In one embodiment, the polymer sheet comprises a polymer based on partially acetalized polyvinyl alcohol (s). In additional embodiments, the polymer sheet comprises (poly) vinyl butyral and one or more additional polymers. In any of the sections herein specifically giving ranges, values and / or preferred methods for the (poly) vinyl butyral (for example and without limitation, for plasticizers, component percentages, thicknesses and feature enhancing additives) , these ranges also apply, if applicable to other polymers or polymer blends set forth herein as useful as components in polymeric sheets. For embodiments comprising (poly) vinyl butyral, (poly) vinyl butyral can be produced by known methods of acetalization which involve reacting polyvinyl alcohol (PVOH) with butyraldehyde in the presence of an acid catalyst, followed by neutralization of catalyst, separation, stabilization and drying of the resin. Details of suitable procedures for making (poly) vinyl butyral are known to those skilled in the art (see, for example, U.S. Patents 2,282,057 and 2,282,026). In one embodiment, the solvent method described in Vinyl Acetal Polymers, in Encyclopedia of Polymer Science & Technology, 3rd edition, Volume 8, pages 381-399, by B.E. Wade (2003). In another embodiment, the aqueous method described in the same source can be used. Poly (vinyl) butyral is commercially available in various forms, for example from Solutia Inc., St. Louis, Missouri as Butvar ™ resin. In various embodiments, resin is used to make the polymer sheet comprising (poly) vinyl butyral comprising from 10 to 35 weight percent (% wt.) Of hydroxyl groups calculated as polyvinyl alcohol, from 13 to 30% wt. of hydroxyl groups calculated as polyvinyl alcohol, or 15 to 22% p. of hydroxyl groups calculated as polyvinyl alcohol. This resin may also comprise less than 15% p. of residual ester groups, 13% p., 11% p., 9% p., 7% p., 5% p. or less than 3% p. of residual ester groups calculated as (poly) vinyl acetate, the remainder being an acetal, preferably butyraldehyde acetal, but optionally including other acetal groups in a minor amount, for example a hexanal 2-ethyl group (see, for example, the patent from US 5,137,954). In various embodiments, the polymer sheet comprises (poly) vinyl butyral having a molecular weight of at least 30,000, 40,000, 50,000, 55,000, 60,000, 65,000, 70,000, 120,000, 250,000 or at least 350,000 grams per mole (g / mol or Daltons). Amounts of a dialdehyde or trialdehyde may also be added during the acetalization step to increase the molecular weight by at least 350 g / mol (see, for example, U.S. Patents 4,902,464, 4,874,814, 4,814,529, and 4,654,179). As used herein, the term "molecular weight" means the weight average molecular weight. Various adhesion control agents can be used in the polymeric sheets of the present invention, including sodium acetate, potassium acetate and magnesium salts. Magnesium salts that can be used with these embodiments of the present invention include, but are not limited to, those set forth in US Pat. 5,728,472, such as magnesium nicotinate magnesium salicylate, di- (2-aminobenzoate) magnesium, di- (3-hydroxy-2-naphthoate) magnesium, and magnesium bis (2-ethylbutyrate) (number of chemical extracts 79992-76-0). In various embodiments of the present invention, the magnesium salt is magnesium bis (2-ethylbutyrate). Additives can be incorporated into the polymer sheet to enhance its performance in a final product. Such additives include, but are not limited to, the following agents: antiblocking agents, plasticizers, colorants, pigments, stabilizers (for example ultraviolet stabilizers), anti-oxidants, flame retardants, IR absorbers and combinations of the foregoing additives and the like, as is known in the art.

In various embodiments of polymeric sheets of the present invention, the polymeric sheets may comprise from 20 to 60, from 25 to 60, from 20 to 80 or from 10 to 70 parts of plasticizer per 100 parts of resin. Of course, other quantities may be used, as appropriate for the particular application. In some embodiments, the plasticizer has a hydrocarbon segment with less than 20, less than 15, less than 12, or less than 10 carbon atoms. The amount of plasticizer can be adjusted to affect the glass transition temperature (Tg) of the (poly) vinyl butyral sheet. In general, larger amounts of plasticizer are added to lower the Tg. The (poly) vinyl butyral polymer sheets of the present invention can have a Tg, for example 50 ° C or less, 40 ° C or less, 35 ° C or less, 30 ° C or less, 25 ° C or less. less, 20 ° C or less and 15 ° C or less. Any suitable plasticizers are added to the polymer resins of the present invention in order to form the polymer sheets. The plasticizers used in the polymeric sheets of the present invention may include esters of a polybasic acid or a polyhydric alcohol, among others. Suitable plasticizers include, for example, triethylene glycol di- (2-ethylbutyrate), triethylene glycol di- (2-ethylhexanoate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyldipate, mixtures of heptyl and nonyl adipates, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, polymeric plasticizers such as modified sebacic alkylates with oil, and mixtures of phosphate and adipates, as set forth in the patent of E.U.A. number 3,841, 890 and adipates as set forth in the patent of E.U.A. No. 4,144,217, and mixtures and combinations of the foregoing. Other plasticizers that can be used are mixed adipates made from alkyl alcohols of C4 to Cg and cyclic alcohols of C4 to C-? 0, as set forth in the patent of E.U.A. No. 5,013,779 and C6 to C8 adipate esters, such as hexyl adipate. In various embodiments, the plasticizer used is adipic acid dihexyl and / or triethylene glycol di-2-ethylhexanoate In various embodiments of the present invention, the polymeric sheets comprise a polymer selected from the group consisting of (poly) vinyl butyral, (poly) vinyl chloride, (poly) ethylene-co-vinyl acetate, (poly) ethylene-co-ethyl acrylate, partially neutralized copolymer ionomers of ethylene / (meth) acrylic acid (such as Surlyn® from DuPont) , polyethylene, polyethylene copolymers, polyurethane or any suitable polymeric material Polymeric resins can be thermally processed and shaped into a sheet according to methods known to those skilled in the art. refers to a polymeric component (eg, poly (vinyl) butyral or (poly) vinyl chloride) of a polymeric composition.The resin will generally have other components besides polymer, for example components that remain in the polymerization process. The resin is mixed with a plasticizer, if required, and optionally with other additives, for example performance enhancing agents, and heated to form a "melt". An exemplary method of forming a (poly) vinyl butyral sheet comprises extruding molten (poly) vinyl butyral comprising resin, plasticizer and additives - the melt - by passing the melt through a sheet mold (e.g. a mold having an opening that is substantially larger in one dimension than in a perpendicular dimension). Another exemplary method of forming a (poly) vinyl butyral sheet comprises casting a melt from a mold to a roll, solidifying the resin and subsequently removing the solidified resin as a sheet. Coextrusion and extrusion coatings are well known in the art. In an exemplary method of forming an intermediate layer of PU / EVA / PU by coextrusion, wherein PU is polyurethane, polyurethane resin, including additives, and an EVA resin of the present invention, including additives, are supplied separately to two single screw extruders. The extruder temperatures for the polyurethane are suitably adjusted, for example at 150 ° C-225 ° C or 160 ° C-180 ° C, and for the EVA, for example at 200 ° C-290 ° C or 240 ° C- 260 ° C. Two resins are heated to form the melts, which are pumped separately into two outer layer channels and one inner layer channel in a coextrusion mold of three distributor tubes. The melts are then passed through a mold flange to form an intermediate layer that has a polymeric EVA sheet disposed between two polyurethane polymer sheets. In any of these embodiments, the layer thicknesses may be the same as those given elsewhere herein for non-extruded embodiments. In other embodiments, the layers can be inverted to produce a constructed intermediate layer having a polyurethane polymer sheet disposed between two EVA polymer sheets.

Polymeric film As used herein, "polymeric film" means a relatively thin and rigid polymeric layer that functions as a performance enhancer layer. Polymeric films differ from polymeric sheets, as used herein, in the sense that polymeric films do not by themselves provide the necessary properties of impact resistance and retention of glass to a multilayer glass structure, rather, it provides performance improvements, such with an infrared radiation absorption character. Poly (ethylene) terephthalate is most commonly used as a polymeric film. The polymeric films used in the present invention can be any suitable film that is sufficiently rigid to provide a relatively flat, stable surface, for example those polymeric films conventionally used as a performance enhancing layer in multilayer glass panels. The polymeric film is preferably optically transparent (ie the objects adjacent to a side of the layer can be viewed comfortably by the eye of a particular observer who is looking through the layer from the other side) and usually has a tensile modulus of elasticity that is greater, in some embodiments significantly greater, regardless of the composition, than that of the adjacent polymer sheet. In various embodiments, the polymeric film comprises a thermoplastic material. Among the thermoplastic materials having suitable properties are nylons, polyurethanes, acrylics - polycarbonates, polyolefins such as polypropylene, acetates and triacetates of cellulose, polymers and copolymers of vinyl chloride and the like. In various embodiments, the polymeric film comprises materials such as re-stretched thermoplastic films that have remarkable properties, which include polyesters. In various embodiments, the polymer film comprises or consists of (poly) ethylene terephthalate and, in various embodiments, (poly) ethylene terephthalate has been biaxially stretched to improve strength and / or stabilized with heat to provide low characteristics of shrinkage, when subjected to high temperatures (for example less than 2% shrinkage in both directions after 30 minutes at 150 ° C). In various embodiments, the polymeric film can have a thickness of 0.013 millimeters to 0.40 millimeters, 0.025 millimeters to 0.2 millimeters or 0.04 to 0.06 millimeters. The polymeric film can optionally be treated or coated on its surface with a functional performance layer to improve one or more properties, such as adhesion or reflection of infrared radiation. These functional performance layers include, for example, a multi-layered stack to reflect infrared solar radiation and transmit visible light, when exposed to sunlight. This multi-layer stacking is known in the art (see, for example, WO 88/01230 and US Pat. No. 4,799,745), and may comprise, for example, one or more metal layers with thickness in Angstroms and one or more (e.g. two) dielectric layers deposited sequentially and optically -cooperated. As is known (see, for example, U.S. Patent Nos. 4,017,661 and 4,786,783), the metallic layers can optionally be heated by electrical resistance to remove frost or mist from any associated glass layers. Various coating and surface treatment methods for polyethylene terephthalate films and other polymeric films that can be used in the present invention are set forth in published European application No. 0157030. The polymeric films of the present invention may also include a layer of hard coating and / or against fog, as is well known in the art. The present invention includes multi-layered glass panels, and particularly glass panels, comprising any intermediate layers of the present invention. The present invention includes methods for making interlayers and multi-layered glass panels, and particularly sandwich panels. glass comprising forming any intermediate layers and glass panels of the present invention of the methods described herein. The present invention includes multi-layered glass panels, and specifically multi-layered glass panels, such as architectural safety glass and for automotive parts, comprising any of the intermediate layers of the present invention. The present invention includes methods of making an intermediate layer, comprising-using a coextrusion process or an extrusion coating process to form any of the intermediate layers of the present invention. The present invention includes methods of manufacturing multi-layered glass panel, comprising arranging any of the intermediate layers of the present invention, with or without additional polymeric layers, between two glass sheets and laminating the stack. The present invention includes methods of securing an enclosed space, comprising disposing in one or more openings provided by access to said space a multi-layered glass panel of the present invention. Also included in the present invention are stacks or rolls of any polymeric intermediate layers of the present invention disclosed herein. In addition to the embodiments given above, other embodiments comprise a rigid glassware substrate other than glass.

In these embodiments, the rigid substrate may comprise acrylic such as Plexiglass®, polycarbonate such as Lexan®, and other plastics, which are conventionally used as glassware. Various features and methods of measuring polymer sheets and / or laminated glasses for use in the present invention will now be described. The transparency of the polymer sheet can be determined by measuring the turbidity value, which is a quantification of the light diffused by a sample in contrast to the incident light. The percentage of turbidity can be measured according to the following procedure. An apparatus can be used to measure the amount of turbidity, or a Hazemeter, model D25, which is obtainable from Hunter Associates (Reston, VA), according to procedure A of ASTM D1003-61 (approved again in 1977), using the regulator C, at an observer angle of 2 degrees. In various embodiments of the present invention, the percentage of turbidity is less than 5%, less than 3% and less than 1%. Adhesion to percussion can be measured according to the following procedure and where "percussion" refers herein to quantify the adhesion of a polymer sheet to a glass, the following procedure is used to determine the percussion. Two-layered glass stratified samples are prepared with standard autoclave stratification conditions. The stratified products are cooled to approximately -17 ° C and are manually hammered with a break the glass. All broken glass that does not adhere to the polyvinyl butyral is then removed and the amount of glass that remains adhered to the polyvinyl butyral sheet is visually compared to a set of standards. The standards correspond to a scale in which several grades of glass remain adhered to the polyvinyl butyral sheet. In particular, at a percussion standard of zero, there is no glass adhering to the polyvinyl butyral sheet. At a percussion standard of 10, 100% of the glass remains adhered to the polyvinyl butyral sheet. For stratified glass panels of the present invention, several embodiments have a percussion of at least 3, at least 5, at least 8, at least 9 or 10. Other embodiments have a percussion between 8 and 10 inclusive. The "yellowness index" of a polymeric sheet can be measured according to the following: Transparent molded discs of 1 cm thick polymeric sheet having smooth polymeric surfaces are formed, which are essentially flat and parallel. The index is measured according to ASTM method D 1925, "standard test method for the yellowness index of plastics" from the spectrophotometric luminous transmittance in the visible spectrum. The values are corrected to 1 cm thick, using the thickness of the specimen measured. In various embodiments of the present invention, a polymer needle may have a yellowness index of 12 or less, 10 or less, or 8 or less.

EXAMPLES EXAMPLE 1 A composition of 100 grams of ethylene-vinyl acetate copolymer having 29.5% by weight of vinyl acetate and 0.1 grams of Millad® (obtainable from Milliken &Company, Spartanburg, South Carolina) is compressed by melting. then by melting at 165 ° C forming a polymeric sheet 0.76 millimeters thick. The resulting sheet exhibits 2% turbidity.

EXAMPLE 2 (Compare) A composition of 100 grams of ethylene-vinyl acetate copolymer having 29.5% by weight of vinyl acetate is compressed by melting at 165 ° C, forming a polymeric sheet of 0.76 millimeters in thickness. The resulting sheet showed 6% turbidity.

EXAMPLE 3 A composition of 100 grams of ethylene-vinyl acetate copolymer having 22% by weight of vinyl acetate and 0.1 grams of Millad 3988 is melt-formed, then compressed by melting at 165 ° C, forming a polymeric sheet 0.76 millimeters thick. The resulting sheet showed 6% turbidity.

EXAMPLE 4 (Comparative) A composition of 100 grams of ethylene-vinyl acetate copolymer having 22% by weight of vinyl acetate is compressed by melting at 165 ° C, forming a polymeric sheet of 0.76 in thickness. The resulting sheet exhibited 20% turbidity. By virtue of the present invention it is now possible to provide intermediate layers having transparent ethylene-vinyl acetate copolymer, which can provide process and cost advantages over the conventional ethylene-vinyl acetate copolymer other types of polymeric sheets. Although the invention has been described with respect to exemplary embodiments, it would be understood by those skilled in the art that various changes may be made and that equivalents may be substituted by elements thereof, without departing from the scope of the invention. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the invention, if departing from the essential scope thereof. Therefore, it is intended that the invention is not limited to the particular embodiments set out as the best mode contemplated, to carry out this invention, but that the invention will include all the modalities that fall within the scope of the appended claims. It will further be understood that the ranges, values or features given for any individual component of the present invention can be used interchangeably with any given ranges, values or characteristics for any of the other components of the invention, if compatible, to form a modality having defined values for each of the components, as given by the present. For example, a polymeric sheet comprising the ethylene-vinyl acetate copolymer with a transparent agent can be formed in any of the given ranges in addition to any of the ranges given for the thickness to form many permutations that are within the scope of the present invention. invention. It is understood that the figures are not drawn to scale, unless otherwise indicated. Each reference, including articles of specialized journals, patents, applications and books, to which reference is made herein, is hereby incorporated by reference in its entirety.

Claims (20)

NOVELTY OF THE INVENTION CLAIMS

1. An intermediate layer for use in a multilayer glass comprising: a first polymeric sheet comprising ethylene-vinyl acetate copolymer and a reaction product of a disubstituted benzaldehyde and a polyhydric alcohol or polyhydric alcohol derivative.

2. The intermediate layer according to claim 1, further characterized in that said intermediate layer comprises additionally a second polymeric sheet arranged in contact with said first polymeric layer, wherein said second polymeric sheet comprises a polymer selected from the group consisting of butyral of (poly) vinyl, (poly) vinyl chloride, (poly) ethylene-co-vinyl acetate, (poly) ethylene-co-ethyl acrylate, ethylene / partially neutralized (meth) acrylic acid copolymer ionomers, polyethylene , polyethylene and polyurethane copolymers.

3. The intermediate layer according to claim 2, further characterized in that said second polymeric sheet comprises (poly) vinyl butyral, ethylene / partially neutralized ethylene / methacrylic acid copolymer ionomers or polyurethane.

4. The intermediate layer according to claim 2, further characterized in that said intermediate layer additionally comprises a third polymeric sheet arranged in contact with said first polymeric sheet, wherein said third polymeric sheet comprises a polymer selected from the group consisting of (poly) vinyl butyral, (poly) vinyl chloride, (poly) ethylene-co-vinyl acetate, (poly) ethylene-co ethyl acrylate, ionomers of ethylene / partially neutralized (meth) acrylic acid copolymer, polyethylene, polyethylene and polyurethane copolymers.

5. The intermediate layer according to claim 4, further characterized in that said second polymeric sheet comprises butyral of partially neutralized ethylene / (meth) acrylic copolymer (poly) vinyl ether-ionomers or polyurethane.

6. The intermediate layer according to claim 1, further characterized in that said intermediate layer consists essentially of said first polymer sheet.

7. The intermediate layer according to claim 1, further characterized in that said reaction product is a reaction product of sorbitol and di-substituted benzaldehyde.

8. The intermediate layer according to claim 1, further characterized in that said reaction product is 1,3: 2,4-bis (3,4'-dimethylbenzylidene) sorbitol.

9. The intermediate layer according to claim 1, further characterized in that said ethylene-vinyl acetate copolymer comprises 0.05 to 3 phr of said reaction product.

10. - The intermediate layer according to claim 1, further characterized in that said ethylene-vinyl acetate copolymer comprises 0.05 to 1 phr of said reaction product.

11. An intermediate layer for use in a multilayer glass, consisting essentially of a polymeric sheet comprising ethylene vinyl acetate copolymer and a reaction product of a disubstituted benzaldehyde and a polyhydric alcohol or polyhydric alcohol derivative .

12. The intermediate layer according to claim 11, further characterized in that said reaction product is a reaction product of sorbitol and disubstituted benzaldehyde.

13. The intermediate layer according to claim 12, further characterized in that said reaction product is 1,3: 2,4-bis (3,4'-dimethylbenzylidene) sorbitol.

14. The intermediate layer according to claim 11, further characterized in that said ethylene-vinyl acetate copolymer comprises 0.05 to 3 phr of said reaction product of sorbitol and disubstituted benzaldehyde.

15. The intermediate layer according to claim 11, further characterized in that said ethylene vinyl acetate copolymer comprises 0.05 to 1 phr of said reaction product of sorbitol and disubstituted benzaldehyde.

16. - A multilayer glass panel comprising an intermediate layer, wherein said intermediate layer comprises: a first polymer sheet comprising ethylene-vinyl acetate copolymer and a reaction product of a disubstituted benzaldehyde and a polyhydric alcohol or derivative polyhydric alcohol.

17. The panel according to claim 16, further characterized in that said intermediate layer further comprises a second polymer sheet disposed in contact with said first polymeric layer, wherein said second polymeric sheet comprises a polymer selected from the group consisting of in (poly) vinyl butyral, (poly) vinyl chloride, (poly) ethylene-vinyl acetate co-acetate, (poly) ethylene-co-ethyl acrylate, ethylene / partially neutralized (meth) acrylic copolymer ionomers , polyethylene, copolymers of polyethylene and polyurethane.

18. The panel according to claim 17, further characterized in that said second polymeric sheet comprises (poly) vinyl butyral, ethylene / partially neutralized ethylene / methacrylic acid copolymer ionomers or polyurethane.

19. The panel according to claim 17, further characterized in that said intermediate layer further comprises a third polymeric sheet arranged in contact with said first polymeric sheet, wherein said third polymeric sheet comprises a polymer selected from the group consisting of butyral of (poly) vinyl, (poly) vinyl chloride, (poly) ethylene-co-vinyl acetate, (poly) ethylene-co-acrylate ethyl, ethylene / partially neutralized (meth) acrylic acid copolymer onomers, polyethylene, polyethylene and polyurethane copolymers.

20. The panel according to claim 19, further characterized in that said second polymeric sheet comprises (poly) vinyl butyral, ethylene / partially neutralized ethylene / methacrylic acid copolymer ionomers or polyurethane.