Recovery of recycled poly(vinyl butyral) polymers

Abstract

A method for recovering poly(vinyl butyral) (PVB), the method comprising the steps of: providing a solvent to a regeneration system; adding recycled PVB to the solvent and agitating to form a PVB mixture, the PVB mixture comprising a liquid portion containing dissolved high PVOH PVB resin and plasticizers and a low PVOH PVB solids and plasticizers; and filtering the PVB mixture to remove the low PVOH PVB solids.

Description

[Technical field]

[0001]

[0001] This invention relates to the field of poly(vinyl butyral) resin production, and more particularly, this invention is in the field of recovery and reuse of post-industrial and post-consumer poly(vinyl butyral), including methods for recovering post-industrial and post-consumer poly(vinyl butyral). [Background technology]

[0002]

[0002] Laminated glass panels, such as automotive windshields and architectural safety glass, are typically composed of two sheets of glass laminated together with a layer of plasticized polymer sandwiched between them, known as the interlayer. Poly(vinyl butyral) ("PVB") is a common polymer that typically forms the major component in the majority of polymer interlayers in automotive windshields and architectural safety glass. Poly(vinyl butyral) resin is typically mixed with a plasticizer before being melt extruded into a sheet.

[0003]

[0003] In recent years, multi-layer poly(vinyl butyral) interlayers have been increasingly marketed for use in laminated safety glass. Multi-layer interlayers can provide improved acoustic insulation due to the presence of a softer layer ("core layer") in the center of the sheet. Typically, the composition of the core layer differs from the composition of the outer layers ("skin layers") in terms of the amount of plasticizer relative to the amount of polymer. The plasticizer content is typically higher in the core layer than in the skin layers. Furthermore, the chemical composition of the PVB resin in the core layer differs from the chemical composition of the PVB resin in the skin layers in terms of hydroxyl content and sometimes also in terms of residual poly(vinyl acetate) content.

[0004]

[0004] One common form of conventional multi-layer interlayer, the three-ply acoustical interlayer, contains a soft core layer of a poly(vinyl butyral) ("PVB") resin having low residual hydroxyl content and a high amount of conventional plasticizers, and two hard skin layers having significantly higher residual hydroxyl content (see, e.g., U.S. Pat. Nos. 5,340,654, 5,190,826, and 7,510,771). Interlayers with the inverse configuration, i.e., one hard layer sandwiched between two softer layers, have been shown to improve the impact performance of glass panels and can also be designed for acoustical insulation.

[0005]

[0005] Generally, PVB resins are produced by a synthesis process that starts with the separation of ethane from natural gas or directly from a petroleum refining process. The ethane is then steam cracked to produce ethene (ethylene), which is used with an acetic acid feedstock to obtain vinyl acetate monomer. The vinyl acetate monomer is polymerized by free radical polymerization to give poly(vinyl acetate). The poly(vinyl acetate) is hydrolyzed or transesterified with methanol and ethanol to give poly(vinyl alcohol), which is then reacted with butyraldehyde to give poly(vinyl butyral). This synthesis process of PVB resins is energy intensive and relies on the use of non-renewable raw materials. Therefore, the prospect of recycled PVB resins derived from post-industrial and post-consumer recycled PVB has long been considered in the art as a potentially valuable source of PVB, which is less costly to produce than virgin PVB resin and can significantly reduce the environmental footprint of PVB production. Exemplary post-industrial raw materials include PVB rolls that are off-specification, damaged, or otherwise unusable, as well as PVB from damaged or defective post-industrial laminated glass. Exemplary post-consumer recycled PVB raw materials include post-consumer automotive windshields and architectural safety glass, as well as other post-consumer consumer products such as power devices (e.g., photovoltaic devices) and electronic display devices.

[0006]

[0006] Trimmings and off-grade uniform monolayer grade poly(vinyl butyral) sheet products can sometimes be directly reused in sheet manufacturing processes. However, both post-industrial and post-consumer PVB generally contain various mixtures of different PVB compositions as obtained from various products and / or different manufacturers, as well as additives such as plasticizers, UV absorbers, solar absorbers, etc. As a result, post-industrial and / or post-consumer PVB mixtures may contain PVB of various poly(vinyl butyral) compositions, including various polyvinyl alcohol contents. Such compositional differences within the mixture of recycled PVB always result in unacceptably high haze and / or discoloration of the PVB, even though other impurities have been removed from the PVB. Specifically, when PVB materials of significantly different compositions are mixed together, chemical incompatibility results in a cloudy or hazy material due to immiscible microdomains with different refractive indices, which greatly limits its reuse as an interlayer in automotive windshields and architectural safety glass applications. Thus, despite a long felt need in the art, there are several problems associated with recycled PVB.

[0007]

[0007] Similarly, multi-layer interlayers have limited recyclability in direct extrusion processes because the different layers typically have compositions that are too different from each other. The acoustic core layer does not mix well with the two skin layer materials, especially during extrusion, forming small but separate domains of core material, which creates a certain level of haze and limits its content in the extrusion. This makes a certain type of haze visible in laminated glass in which the multi-layer sheet pieces contain the PVB sheet used in the raw material supply, which results in products with poor appearance that are not suitable for sale in the market or do not meet certain quality requirements for certain products. The inability to recycle this multi-layer material is a significant economic loss. Therefore, maximizing the reuse of multi-layer scrap, off-cuts, and recycled PVB is not only a competitive advantage, but also an environmentally friendly practice.

[0008] In view of the above, there is a need to process post-industrial and / or post-consumer PVB in a manner that not only can remove plasticizers from recycled PVB material but also can separate the core layer from the skin layers of multi-layer interlayers so that the PVB obtained from the skin layers is a transparent polymer that can be used to make new PVB resins and interlayers, such as those that may be incorporated into new laminated glass panels. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a flow chart of a method for recovering PVB, according to an embodiment of the present invention. [Diagram 2]

[0010] GPEC chromatograms showing recycled PVB extracts in ethanol containing 9 wt.% (top), 16 wt.% (middle), and 20 wt.% (bottom) water. [Diagram 3]

[0011] FIG. 1 shows GPEC chromatograms of recycled PVB extract in methanol containing 0 wt.% (top), 9.5 wt.% (middle), and 4.9 wt.% (bottom) water. [Figure 4]

[0012] GPEC chromatograms showing recycled PVB extract in isopropanol containing 0 wt.% (top) and 32 wt.% water (bottom). [Diagram 5]

[0013] FIG. 1 is a schematic diagram of a process for selective dissolution and separation by filtration of recycled PVB resin. [Figure 6]

[0014] GPEC chromatograms of the suspension sample after dissolution in methanol containing 4 wt.% water (top), the starting mixture (middle), and the final filtrate sample (bottom). [Figure 7]

[0015] GPEC chromatograms of the suspension sample (top) and the combined filtrate (bottom) after dissolution in ethanol containing 20 wt.% water. [Figure 8]

[0016] FIG. 1 is a schematic diagram of the process of selective dissolution of recycled PVB flakes and separation by filtration and washing or centrifugation and washing. [Figure 9]

[0017] FIG. 1 is a GPEC chromatogram showing recycled PVB in ethanol with starting material (recycled pellets in ethanol) (top), supernatant after centrifugation (middle), and precipitated material (bottom), which represents mainly the core resin. [Figure 10]

[0018] GPEC chromatograms showing recycled PVB pellets in ethanol (top) and recycled PVB flakes in ethanol (bottom) from the supernatant after centrifugation. [Figure 11]

[0019] GPEC chromatograms showing 10 wt.% recycled PVB pellets in ethanol from the supernatant after the first centrifugation (top) and 5 wt.% recycled PVB pellets in ethanol from the supernatant after the first centrifugation (bottom). [Figure 12]

[0020] FIG. 1 shows GPEC chromatograms of 5 wt.% recycled PVB pellets in ethanol with the supernatant after the first centrifugation (top) and with the supernatant after the second centrifugation (bottom). [Figure 13]

[0021] FIG. 1 shows GPEC chromatograms of 10 wt.% recycled PVB pellets in ethanol with the supernatant after the first centrifugation (top) and with the supernatant after the second centrifugation (bottom). [Figure 14]

[0022] FIG. 1 is a schematic diagram of a laminated glass panel including a pair of glass sheets facing a polymer interlayer, the polymer interlayer including three layers having a pair of skin layers facing a core layer. [Figure 15]

[0023] FIG. 2 is another schematic diagram of a laminated glass panel including a pair of glass sheets facing a polymer interlayer, the polymer interlayer having a wedge shape. Summary of the Invention [Means for solving the problem]

[0010]

[0024] One aspect of the invention is a method for recovering poly(vinyl butyral) (PVB) comprising: (a) providing a solvent to a regeneration system; (b) adding recycled PVB to the solvent and stirring to form a PVB mixture, the PVB mixture comprising a liquid portion comprising dissolved high PVOH PVB resin and plasticizer and a solid portion comprising low PVOH PVB solids; and (c) filtering the PVB mixture to remove the low PVOH PVB solids. The removed low PVOH PVB solids may include residual high PVOH PVB resin and plasticizer. The method may further comprise the step (d) of separating the residual high PVOH PVB resin and plasticizer from the low PVOH PVB solids.

[0011]

[0025] Another aspect of the invention relates to a method for recovering poly(vinyl butyral) (PVB) comprising: (a) feeding a solvent to a regeneration system; (b) adding recycled PVB to the solvent and stirring to form a PVB mixture, the PVB mixture comprising a liquid portion comprising dissolved high PVOH PVB resin and plasticizer and a solid portion comprising low PVOH PVB solids; and (c) filtering the PVB mixture to remove low PVOH PVB solids, the removed low PVOH solids comprising residual high PVOH PVB resin and plasticizer. The removed low PVOH PVB solids may comprise residual high PVOH PVB resin and plasticizer. The method may further comprise a step (d) of separating the residual high PVOH PVB resin and plasticizer from the low PVOH PVB solids. The low PVOH solids may contain less than 20% (15%, 10%, 5%, 4%, 3%, 2%, 1%) high PVOH PVB resins derived from recycled PVB.

[0012]

[0026] One aspect of the present invention relates to a method for recovering poly(vinyl butyral) (PVB) from skin layers of a three-layer interlayer. This method is more suitable for materials with a well-dispersed composition in the feed, such as extruded and pelletized materials from recycled multi-layer PVB interlayers. The method includes feeding a solvent to a regeneration system. A further step includes adding recycled PVB to the solvent and stirring at a specific temperature for a specified time to form a PVB mixture. The PVB mixture is stirred to dissolve PVB resins with high poly(vinyl alcohol) ("PVOH") levels (referred to herein as high PVOH PVB resins) and plasticizers, while retaining PVB resins with low PVOH levels (referred to herein as low PVOH PVB resins) as solids. Often, the high PVOH resins are present in the skin or outer layer(s) of the multi-layer interlayer. A further step includes filtering and / or optionally centrifuging the PVB mixture to remove low PVOH PVB solids from the solution. This step may be repeated multiple times, such as until the high PVOH PVB (skin) resin and plasticizer are completely dissolved. Further steps include subjecting the solution to further processing, such as evaporation, vacuum and / or heat, or other processes known to those skilled in the art, to obtain a recovered high PVOH PVB polymer containing the plasticizer. Further steps may include separating the plasticizer from the recovered high PVOH PVB polymer.

[0013]

[0027] Another aspect of the invention relates to a recovered poly(vinyl butyral) (PVB) polymer. The recovered PVB polymer is produced by a process that includes feeding a solvent to a regeneration system. A further step includes adding recycled PVB to the solvent and stirring at a specific temperature for a specified time to form a PVB mixture. The PVB mixture is stirred to dissolve the high PVOH PVB (skin) resin and plasticizer while retaining the low PVOH PVB (core) resin as a solid. A further step includes filtering and / or optionally centrifuging the PVB mixture to remove the low PVOH PVB solids from the solution. This step may be repeated multiple times, such as until the high PVOH PVB (skin) resin and plasticizer are completely dissolved. A further step includes subjecting the solution to further processing, such as evaporation, vacuum and / or heat, or other processes known to those skilled in the art, to obtain a recovered high PVOH PVB polymer containing the plasticizer. A further step may include separating the plasticizer from the recovered high PVOH PVB polymer.

[0014]

[0028] Another aspect of the invention relates to a laminated glass panel comprising an interlayer comprising recycled poly(vinyl butyral) (PVB). The recycled PVB is produced by a process comprising feeding a solvent to a reclamation system. A further step comprises adding recycled PVB to the solvent and stirring at a specified temperature for a specified time to form a PVB mixture. The PVB mixture is stirred to dissolve the high PVOH PVB (skin) resin and plasticizer while retaining the low-PVOH PVB (core) resin as a solid. A further step comprises filtering and / or optionally centrifuging the PVB mixture to remove the low PVOH PVB solids from the solution. This step may be repeated multiple times, such as until the high PVOH PVB (skin) resin and plasticizer are completely dissolved. A further step comprises subjecting the solution to further processing, such as evaporation, vacuum and / or heat, or other processes known to those skilled in the art, to obtain a recycled high PVOH PVB polymer containing the plasticizer. A further step may comprise separating the plasticizer from the recycled high PVOH PVB polymer.

[0015]

[0029] One aspect of the present invention relates to a method for recovering poly(vinyl butyral) (PVB) from the skin layers of a three-ply interlayer. This method is more suitable for feeds that are still in layered form, such as ground multi-layer interlayer material, where the undissolved material can maintain a consistent shape and size during the operation. The method includes feeding a solvent to a regeneration system. A further step includes adding recycled PVB to the solvent and stirring at a specific temperature for a specified time to extract the high PVOH PVB (skin) resin and plasticizer, while retaining the low PVOH PVB (core) resin as a solid. A further step includes collecting the low PVOH PVB resin on a coarse screen. This step may be repeated multiple times, such as until the high PVOH PVB (skin) resin and plasticizer are completely extracted. A further step includes subjecting the extract to further processing, such as evaporation, vacuum and / or heat, or other processes known to those skilled in the art, to obtain a recovered high PVOH PVB polymer containing the plasticizer. A further step may include separating the plasticizer from the recovered high PVOH PVB polymer.

[0016]

[0030] Another aspect of the invention relates to a recovered poly(vinyl butyral) (PVB) polymer. The recovered PVB polymer is produced by a process that includes feeding a solvent to a regeneration system. A further step includes adding recycled PVB to the solvent and stirring at a specified temperature for a specified time to extract the high PVOH PVB (skin) resin and plasticizer while retaining the low PVOH PVB (core) resin as a solid. A further step includes collecting the low PVOH PVB resin on a coarse screen. This step may be repeated multiple times, such as until the high PVOH PVB (skin) resin and plasticizer are completely extracted. A further step includes subjecting the extract to further processing, such as evaporation, vacuum and / or heat, or other processes known to those skilled in the art, to obtain a recovered high PVOH PVB polymer containing the plasticizer. A further step may include separating the plasticizer from the recovered high PVOH PVB polymer.

[0017]

[0031] Another aspect of the invention relates to a laminated glass panel comprising an interlayer comprising recycled poly(vinyl butyral) (PVB). The recycled PVB is produced by a process comprising feeding a solvent to a reclamation system. A further step comprises adding recycled PVB to the solvent and stirring at a specified temperature for a specified time to extract the high PVOH PVB (skin) resin and plasticizer while retaining the low PVOH PVB (core) resin as a solid. A further step comprises collecting the low PVOH PVB resin on a coarse screen. This step may be repeated multiple times, such as until the high PVOH PVB (skin) resin and plasticizer are completely extracted. A further step comprises subjecting the extract to further processing, such as evaporation, vacuum and / or heat, or other processes known to those skilled in the art, to obtain a recovered high PVOH PVB polymer containing the plasticizer. A further step may comprise separating the plasticizer from the recovered high-PVOH PVB polymer.

[0018]

[0032] Another aspect includes further processing the recovered high PVOH PVB polymer, such as in a reacetalization process. Further processing of the recovered high PVOH PVB may include adding the recovered PVB polymer to a solvent, such as an alcohol, and stirring with a specific amount of catalyst and a specific amount of butyraldehyde at a specific temperature for a specified time to dissolve and equilibrate the recovered high PVOH PVB polymer into a PVB solution. A further step includes filtering the PVB solution to remove undissolved solids. A further step includes neutralizing the PVB solution with a base, such as potassium hydroxide (KOH). A further step includes precipitating the neutralized PVB solution and washing with water to remove the solvent to obtain a PVB solid. A further step includes filtering the resulting PVB solid and drying the filtered PVB solid to obtain the recovered PVB polymer. In an embodiment, the PVB polymer may be of a single composition (i.e., of known or uniform composition, such as from a single source and having the same or similar properties, such as the same residual hydroxyl level). In other embodiments, the PVB polymer may be of heterogeneous composition derived from multiple or unknown sources.

[0019]

[0033] Another embodiment includes further processing the recovered high PVOH PVB polymer, which is of a single polymer composition. When the PVB polymer is of a single (i.e., known or uniform) composition, the recovered PVB polymer can be directly processed. Further processing of the recovered PVB may include a further step of adding the recovered PVB polymer to a solvent, such as alcohol, and stirring at a specific temperature until the recovered PVB polymer is completely dissolved to form a PVB solution. A further step includes filtering the PVB solution to remove undissolved solids. A further step includes precipitation of the PVB solution and washing with water to remove the solvent to obtain a PVB solid. A further step includes filtering the resulting PVB solid and drying the filtered PVB solid to obtain a recovered PVB polymer, which is of a single or uniform composition. Alternatively, instead of precipitation, a further step after filtration includes evaporating the solvent to obtain a recovered PVB polymer, which is of a single or uniform composition.

[0020]

[0034] Another aspect includes further processing the recovered low PVOH PVB polymer, such as in a reacetalization process. Further processing of the recovered low PVOH PVB may include adding the recovered PVB polymer to a solvent, such as an alcohol, and stirring with a specific amount of catalyst and a specific amount of butyraldehyde at a specific temperature for a specified time to dissolve and equilibrate the recovered low PVOH PVB polymer into a PVB solution. A further step includes filtering the PVB solution to remove undissolved solids. A further step includes neutralizing the PVB solution with a base, such as potassium hydroxide (KOH). A further step includes precipitating the neutralized PVB solution and washing with water to remove the solvent to obtain a PVB solid. A further step includes filtering the resulting PVB solid and drying the filtered PVB solid to obtain the recovered PVB polymer. In an embodiment, the PVB polymer may be of a single composition (i.e., of known or uniform composition, such as from a single source and having the same or similar properties, such as the same residual hydroxyl level). In other embodiments, the PVB polymer may be of heterogeneous composition derived from multiple or unknown sources.

[0021]

[0035] Another embodiment includes further processing the recovered low PVOH PVB polymer, which is of a single polymer composition. When the PVB polymer is of a single (i.e., known or uniform) composition, the recovered PVB polymer can be directly processed. Further processing of the recovered PVB may include a further step of adding the recovered PVB polymer to a solvent, such as alcohol, and stirring at a specific temperature until the recovered PVB polymer is completely dissolved to form a PVB solution. A further step includes filtering the PVB solution to remove undissolved solids. A further step includes causing precipitation in the PVB solution and washing with water to remove the solvent to obtain a PVB solid. A further step includes filtering the resulting PVB solid and drying the filtered PVB solid to obtain a recovered PVB polymer, which is of a single or uniform composition. Alternatively, instead of precipitation, a further step after filtration includes evaporating the solvent to obtain a recovered PVB polymer, which is of a single or uniform composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022]

[0036] An embodiment of the present invention is directed to a method of recovering, recycling, and / or reusing poly(vinyl butyral) ("PVB"). More particularly, an embodiment of the present invention is directed to a method of recycling post-industrial and / or post-consumer recycled PVB to obtain a sufficient amount of PVB polymer that can be used to form polymer interlayers and / or laminated glass panels including polymer interlayers, or can be used in other processing steps. More particularly, FIG. 1 shows an exemplary method of recycling PVB according to an embodiment of the present invention. The method includes a step S1 of providing a solvent to a regeneration system. The solvent may be an alcohol, or a mixture of alcohol and water containing a certain amount of water, such that the low PVOH PVB is not soluble in the solvent (such as alcohol or an alcohol-water mixture). The solvent or solvent mixture is agitated. The method may include a further step S2 of adding recycled PVB material to the solvent to form a PVB mixture. This recycled material may take the form of a film (which may optionally be chopped, shredded or cut into small pieces, as further described below), or an extruded film into pellets, or any other structure derived from the starting multilayer film. The recycled PVB may contain at least some plasticizer. A further step S3 may include stirring the PVB mixture for a specified time at a specified temperature to allow the high PVOH PVB and plasticizer to be dissolved or extracted from the recycled PVB to form a mixture of liquid and low PVOH PVB solids. A further step S4 may include filtering the PVB mixture to remove the low PVOH PVB solids. This version of step S4 is more appropriate when the starting material is in the form of extruded pellets. Alternatively, step S4 may include passing the solution containing the low PVOH solids through a screen (such as a coarse screen) to remove the low PVOH PVB solids. In general, the use of a screen in step S4 is more appropriate when the starting material is in a film form instead of a pelletized form.

[0023]

[0037] A further step S5 may include determining the levels of plasticizer and high PVOH PVB in the low PVOH PVB solids to determine if further reclamation is required. If the amount of high PVOH exceeds the desired level in the low PVOH PVB solids, the process may be repeated by returning the low PVOH PVB solids to step S1 and repeating the steps.

[0024]

[0038] A further step S6 may include independently processing or treating either or both of the removed PVB polymers, the high PVOH PVB polymer or the low PVOH PVB polymer, such as rinsing the low PVOH portion with fresh solvent to remove the high PVOH and plasticizer to further improve separation, or by heat, evaporation, and / or vacuum to form a dried PVB polymer or a dissolved PVB solution. Step S6 may optionally include further processing of the dried PVB polymer or the dissolved PVB solution. The recovered low PVOH PVB polymer will not retain a significant portion of the plasticizer or high PVOH PVB polymer and may not contain detectable levels of plasticizer and / or high PVOH PVB polymer. The resulting PVB polymer recovered during the above steps, either the high PVOH PVB polymer or the low PVOH polymer, or both, may independently be further processed or may be of sufficient quality (e.g., sufficient transparency and / or color) to be partially or completely used in commercial products such as the manufacture of polymer interlayers and / or laminated glass panels that include the polymer interlayers, or to be used in resin manufacturing processes and reacetalized to form PVB resins. The recovered PVB can also be used in other applications, such as adhesives that can be formed with the recovered PVB, as well as flooring, ceramic compositions, binders, coatings, inks, dispersions, and other applications.

[0025]

[0039] The inventors have found that a solvent comprising alcohol or a mixture of alcohol and water will only dissolve the plasticizer and high PVOH PVB if water is present in a certain amount or level (as explained below), with minimal dissolution of the low PVOH PVB in this process. If there is too much water in the solvent mixture, only the plasticizer will dissolve in the solvent, and if there is too little water in the solvent mixture (depending on the solvent), all three components, i.e., the high PVOH PVB, a significant amount of the low PVOH PVB, and the plasticizer will dissolve in the solvent. Therefore, the solvent must be prepared and selected with a specific optimum amount of water so that only the high PVOH PVB and the plasticizer will dissolve and be separated from the low PVOH PVB resin.

[0026]

[0040] Preferred alcohols for the alcohol-water solvent mixture are ethanol, methanol, and isopropanol. When the alcohol is ethanol, the optimum range of the weight percent water in the ethanol / water solvent mixture in the extraction of plasticizer and high PVOH PVB resin from recycled PVB is about 16-24% water by weight, or about 20-about 24%, or at least 16%, at least 17%, at least 18%, at least 19%, at least 20% or more, and about 24% or less, less than 24%, less than 23%, less than 22%, or less than about 21% water. When the amount of water in the ethanol / water mixture exceeds about 24% water by weight, the solubility of the high PVOH PVB resin in the alcohol / water mixture becomes very limited. When the water content in the ethanol / water solvent mixture is less than about 20%, the low PVOH PVB resin begins to become soluble, and when the water content is less than about 16%, the low PVOH PVB resin becomes very soluble.

[0027]

[0041] Similarly, when using a solvent mixture of methanol and water, the range of water is from little to no water (i.e., about 0%) to about 9.5% water by weight, or no water at all, or more than 0%, more than 0.5%, more than 1.0%, more than 1.5%, more than 2.0%, more than 2.5%, more than 13.0%, more than 3.5%, more than 4.0%, more than 4.5%, more than 5.0%, more than 5.5%, or less than about 9.5%, less than 9.0%, less than about 8.5%, less than 8.0%, less than about 7.5%, less than 7.0%, less than about 6.5%, less than 6.0%, or from about 4.0 to about 6.0%. When the amount of water in the methanol / water mixture is greater than about 9.5% water by weight, the solubility of the high PVOH PVB in the alcohol / water mixture becomes so low that the solvent is no longer effective in isolating the resin. When the water content in the methanol / water solvent mixture is below about 4.0%, the low PVOH PVB resins begin to become soluble, and as the water level decreases towards 0%, the low PVOH PVB resins become increasingly soluble.

[0028]

[0042] Finally, a solvent mixture of water and isopropanol can be used, however, the solubility of PVB in the solution is low and the high PVOH PVB resin is not well extracted into the solvent compared to the plasticizer when compared to the extraction efficiency and yield of both the ethanol and methanol solvent systems. For this reason, isopropanol is a less suitable alcohol to use in this process than alcohols such as ethanol and methanol, however, higher levels or amounts of water in the solvent mixture may be required when using isopropanol.

[0029]

[0043] Although the amount of water used is described within a particular range, the particular amount of water in each solvent mixture described herein and in many of the examples below is appropriate for a particular level of PVOH in the PVB layers (i.e., skin and core layers). For example, some recycled PVB materials contain high PVOH polymers in the skin resins with residual PVOH levels of about 18-20 weight percent (wt.%) and low PVOH polymers in the core resins with residual PVOH levels of about 9-11 wt.%. Depending on the composition of the PVB mixture, it may be necessary to increase or decrease the amount of water in the solvent mixture to ensure optimal separation of the components.

[0030]

[0044] Haze is the percentage of transmitted light that is scattered, so that its direction deviates from the direction of the incident beam by more than a specified angle. Haze can be measured using a haze meter or spectrophotometer known to those skilled in the art in accordance with ASTM D1003-Procedure B at a 2 degree observation angle using Illuminant C. In some embodiments, glass panels, polymer layers, and / or interlayers incorporating the recovered high PVOH PVB described herein may have a haze value of less than 5 percent, less than about 4 percent, less than about 3 percent, less than about 2 percent, less than about 1, or less than about 0.5 percent.

[0031]

[0045] The recycled PVB fed to the regeneration system in step S2 may include post-industrial and / or post-consumer recycled PVB. Such post-industrial recycled PVB may include PVB rolls that are out of specification, damaged, or otherwise unusable, while such post-consumer recycled PVB may include material recovered from previously manufactured and / or used automotive windshields and architectural safety glass, as well as end or other off-cut materials. Recycled PVB material may also include scrap or post-consumer material from other consumer products, such as power devices (e.g., photovoltaic devices), electronic display devices, and other sources.

[0032]

[0046] Recycled PVB materials may have different PVB compositions, such as different amounts of polyvinyl alcohol ("PVOH"), as well as different amounts and types of plasticizers and other additives. As used herein, low-PVOH PVB polymer refers to PVB having a residual PVOH content of about 8 wt.% to 15 wt.%, or at least about 8 wt.%, at least about 9 wt.%, at least about 10 wt.%, at least about 11 wt.%, at least about 12 wt.%, at least about 13 wt.%, or at least about 14 wt.%, or less than about 15 wt.%, less than about 14 wt.%, less than about 13 wt.%, or less than about 12 wt.%, while high PVOH PVB polymer refers to PVB having a residual PVOH content of about 8 wt.% to 15 wt.%, or at least about 8 wt.%, at least about 9 wt.%, at least about 10 wt.%, at least about 11 wt.%, at least about 12 wt.%, at least about 13 wt.%, or at least about 14 wt.%, or less than about 15 wt.%, less than about 15 wt.%, less than about 14 wt.%, less than about 13 wt.%, or less than about 12 wt.%. PVB polymer refers to PVB having a residual PVOH content of about 17 wt.% to 27 wt.%, or at least about 17 wt.%, at least about 18 wt.%, at least about 19 wt.%, at least about 20 wt.%, at least about 21 wt.%, at least about 22 wt.%, at least about 23 wt.%, or at least about 24 wt.%, or less than about 27 wt.%, less than about 26 wt.%, less than about 25 wt.%, less than about 24 wt.%, about 23 wt.%, or less than about 22 wt.%, although other amounts may be used as needed or available. Additionally, multiple different PVB resins may be present in recycled PVB. For example, a first portion of the recycled PVB may have a PVOH amount of about 9-15 wt.%, a second portion of the recycled PVB may have a PVOH amount of about 15-20 wt.%, and a third portion of the recycled PVB may have a PVOH amount of about 20-27 wt.%. Generally, the recycled PVB may have a PVOH amount of about 8 to about 27 wt.%, or more, although other amounts are possible depending on the starting materials. These PVOH amounts are for illustrative purposes only, and other ranges of PVOH amounts (or different PVOH ranges) are possible depending on the materials used and the source of the materials.

[0033]

[0047] Recycled PVB may contain an amount of plasticizer (or a different amount of plasticizer depending on the starting recycled PVB), which is generally used to soften the PVB and / or to increase the glass transition temperature Tg Contemplated plasticizers include, but are not limited to, esters of polybasic acids, polyhydric alcohols, triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexanoate) (known as "3-GEH"), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, mixtures of heptyl adipate and nonyl adipate, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and polymeric plasticizers such as oil-modified sebacic acid alkyds, and mixtures of phosphates and adipates, and mixtures and combinations thereof. In some embodiments, 3-GEH is particularly preferred. Other examples of suitable plasticizers include, but are not limited to, tetraethylene glycol di(2-ethylhexanoate) ("4-GEH"), di(butoxyethyl)adipate, and bis(2-(2-butoxyethoxy)ethyl)adipate, dioctyl sebacate, nonylphenyl tetraethylene glycol, and mixtures thereof. Generally, the plasticizer content of a PVB material (e.g., resin or scrap) will be measured on a weight / weight basis as parts per hundred parts of resin ("phr"). For example, if 30 grams of plasticizer are added to 100 grams of polymer resin, the plasticizer content of the resulting plasticized polymer will be 30 phr. Recycled PVB materials may have various amounts and / or types of plasticizers.

[0034]

[0048] The recycled PVB material may be cut, chopped, and / or shredded to form small diameter (e.g., 2-20 mm, although other sizes including up to 1 cm may be used depending on the equipment and other factors) chips, granules, pellets, or flakes of PVB material (chips, granules, pellets, flakes, etc. are referred to herein as "ground PVB material"). Ground PVB material, such as flakes, chips, and / or pellets of PVB material, may be combined with one another to form a mixed composition (e.g., having mixed amounts of PVOH or other elements), or ground PVB from one source (such as PVB rolls having a known composition) may be used alone. Such ground PVB material may be fed into a regeneration system, which may be in the form of a single batch reactor recycle system or a continuous regeneration recycle system. For example, the single batch reactor may include a tank in the form of a continuous stirred tank reactor (CSTR) or another similar reactor, such as a countercurrent screw press extractor or other equipment known to those skilled in the art. One or more (or all) of the steps of the methods described herein may be carried out in a single batch reactor. Alternatively, a continuous regenerative system may be used, which includes multiple interconnected vessels (e.g., CSTRs) or multiple compartments in a tubular arrangement. In a continuous regenerative system, each of the steps may be carried out independently in one or more of the multiple vessels or multiple compartments in a tubular arrangement. Benefits of a continuous regenerative system may include higher throughput and higher efficiency compared to a single batch reactor.

[0035]

[0049] Referring to step S1, the solvent added to the regeneration system (e.g., a single batch reactor recycle system or a continuous regeneration recycle system) may include a variety of solvents sufficient to selectively dissolve the components of the recycled PVB material to form a solution or mixture. Examples of suitable solvents may include a mixture of one or more alcohols, such as ethanol, methanol, or isopropanol, optionally with a sufficient amount of water to selectively dissolve one or more components of the recycled PVB (e.g., one or more of the plasticizers and PVB resin, as well as other additives, such as UV absorbers, solar or infrared absorbers, antioxidants, etc.). The solvent mixture is configured to selectively dissolve the high PVOH PVB resin (and plasticizer) of the recycled PVB material to form a PVB solution from which the low PVOH PVB resin can be filtered from the dissolved high PVOH resin, solvent, and plasticizer (and other materials and impurities). The separated or removed low PVOH PVB solids may include the residual high PVOH PVB resin and plasticizer. The method may further include the step (d) of separating the residual high PVOH PVB resin and plasticizer from the low PVOH PVB solids.

[0036]

[0050] Referring to step S2, recycled PVB is added to the regeneration system (and solvent) and stirred to form a PVB mixture.

[0037]

[0051] Referring to step S3, the PVB mixture may be stirred for a period of time. The stirring time may be at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours or more, although other times may be appropriate. The mixture may be stirred at room temperature (about 22-23°C), or the mixture may be heated to a temperature above room temperature, such as at least about 5°C, at least 10°C, at least 15°C, at least 20°C, at least 25°C, at least 30°C, at least 35°C, at least 40°C, at least 45°C, at least 50°C, at least 55°C, or at least about 60°C or more. The stirring time and temperature are selected to be effective to extract the plasticizer from the recycled PVB. In some embodiments, the stirring temperature is from about 10°C to about 30°C, or from about 15°C to about 25°C. In other embodiments, the stirring temperature is about 5°C to about 60°C, about 5°C to about 50°C, about 5°C to about 40°C, about 5°C to about 30°C, 5°C to about 20°C, or about 5°C to about 10°C.

[0038]

[0052] Referring to step S4, this step includes filtering the PVB mixture to remove low PVOH PVB polymer solids from the mixture. In some embodiments, the filter may include a screen, mesh, cloth, or other similar filtering element. With respect to step S4, the solvent, plasticizer, and high PVOH PVB resin (and other impurities) may be removed from the PVB mixture to obtain a recovered low PVOH PVB polymer. As described in more detail below, after the initial filtering step, the high PVOH PVB may still retain significant levels of the original plasticizer and low PVOH PVB. As such, it may be necessary to return the low PVOH PVB to steps S1 or S2 of the reclaiming process to further dissolve (and extract) the plasticizer and high PVOH PVB resin. The return to the beginning of the process may be performed one or more times, and in embodiments, the return to the beginning of the process is repeated until the plasticizer and high PVOH PVB resin are completely removed or removed to undetectable levels. The recovered PVB may have some residual plasticizer and high PVOH PVB (if desired), or after multiple repetitions (discussed further below), may be free of detectable levels of plasticizer and high PVOH PVB, or may have very small amounts of plasticizer and high PVOH PVB (i.e., the recovered PVB may retain low levels of the original plasticizer and high PVOH PVB included as part of the original recycled PVB).

[0039]

[0053] Referring to step S5, the recovered PVB solids can be analyzed to determine the amount of residual plasticizer and high PVOH PVB resin in the recovered low PVOH PVB solids, and if the levels of plasticizer and high PVOH PVB resin are too high (i.e., above undetectable levels or above desired levels), the recovered low PVOH PVB solids may be returned to the regeneration system after step S1 (where fresh solvent is added or present in the regeneration system).

[0040]

[0054] Referring to step S6, either the high PVOH PVB polymer, the low PVOH polymer, or both may independently have the solvent (alcohol and water) removed, such as by drying, evaporation, or vacuum removal of the alcohol and water. For example, the recovered PVB solids (high PVOH, low PVOH, or both) may be dried, such as in an oven, at a particular temperature for a period of time to form a dry PVB polymer. The drying time may be at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 6 hours, at least 7 hours, at least 8 hours, at least 9 hours, at least 10 hours, at least 11 hours, at least 12 hours or more. The drying temperature may be at least about 20° C., at least about 25° C., at least about 30° C., at least about 35° C., at least about 40° C., at least about 45° C., at least about 50° C., at least about 55° C., at least about 60° C., at least about 65° C., at least about 70° C. or more. The drying time and temperature may vary depending on the method used to dry or remove the water and alcohol.

[0041]

[0055] In another embodiment, the recovered PVB solid, either the high PVOH PVB polymer, the low PVOH polymer, or both, may be independently dissolved in a solvent such as alcohol for further processing without the need for drying or solvent removal. If the recovered PVB polymer is a known or homogeneous polymer, the recovered PVB polymer can be further processed directly. Further processing of the recovered PVB may include a further step of adding the recovered PVB polymer to a solvent such as alcohol and stirring at a certain temperature until the recovered PVB polymer is completely dissolved to form a PVB solution. A further step includes filtering the PVB solution to remove undissolved solids. A further step includes causing precipitation in the PVB solution and washing with water to remove the solvent to obtain a PVB solid. A further step includes filtering the resulting PVB solid and drying the filtered PVB solid to obtain a recovered PVB polymer, the recovered PVB polymer being of a single or homogeneous composition. Alternatively, instead of precipitation, a further step after filtration includes evaporating the solvent to obtain a recovered PVB polymer, the recovered PVB polymer being of a single or homogeneous composition.

[0042]

[0056] When the recovered PVB, either the high PVOH PVB polymer, the low PVOH polymer, or both, are independently mixed or of heterogeneous composition, further processing of the recovered PVB may include adding the recovered PVB polymer to a solvent such as alcohol and stirring with a specific amount of catalyst and a specific amount of butyraldehyde at a specific temperature for a specified time to dissolve and equilibrate the recovered PVB polymer into a single PVB solution having a specified PVOH%. A further step includes filtering the PVB solution to remove undissolved solids. A further step includes neutralizing the PVB solution with a base such as potassium hydroxide (KOH) to form a neutralized PVB solution. A further step includes precipitating the neutralized PVB solution and washing with water to remove the solvent to obtain a PVB solid. A further step includes filtering the resulting PVB solid and drying the filtered PVB solid to obtain the recovered PVB polymer.

[0043]

[0057] The recovered high PVOH PVB polymer may optionally be used in an extrusion process (e.g., via an extruder or co-extruder) to form a PVB interlayer and / or a laminated glass panel including a PVB interlayer. The resulting recovered high PVOH PVB polymer, especially in the case of post-industrial recycled materials, may be of sufficient quality and / or transparency to be used in commercial applications, such as the manufacture of polymer interlayers and / or laminated glass panels including polymer interlayers.

[0044]

[0058] Recycled low PVOH PVB polymers may also be optionally used in extrusion processes (e.g., by extruder or co-extruder) to form PVB interlayers and / or laminated glass panels containing PVB interlayers. In particular, however, recycled low PVOH PVB polymers may retain very little or even none of the plasticizers originally contained in the recycled PVB. For example, in some embodiments, recycled low PVOH PVB polymers may retain about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1.5% or less, about 0.5% or less, or about 0% (or levels that are undetectable) of the plasticizers contained in the original recycled PVB. Therefore, it may be necessary to add additional plasticizers before extrusion or other further processing.

[0045]

[0059] In certain embodiments, steps S1-S6 above may be modified, added, and / or removed. Additionally, the recovered PVB polymer (high PVOH PVB and / or low PVOH PVB) may be further processed as described above.

[0046]

[0060] Furthermore, in addition to the above steps, centrifugation can also be used to separate the low PVOH PVB resin from the solution. First, the intermediate layer is treated with a solvent system (as described above) that dissolves only one of the two resins in the mixture, and then the resulting suspension is subjected to centrifugation to facilitate separation. Complete or partial removal of one component (such as the high PVOH or low PVOH PVB resin) can help reduce haze in recycling.

[0047]

[0061] The PVB recovered using the above recovery method steps can be used to form resins, resin layers, polymer interlayers, and / or laminated glass panels that include polymer interlayers. As used herein, the terms "polymer interlayer sheet", "interlayer", "polymer layer", and "polymer melt sheet" may refer to a monolayer sheet or a multilayer interlayer. A "monolayer sheet", as the name implies, is a single polymer layer that is extruded as one layer. A multilayer interlayer, on the other hand, may include multiple layers, including separately extruded layers, coextruded layers, or any combination of separately extruded layers and coextruded layers. Thus, a multilayer interlayer may include, for example, two or more monolayer sheets combined with each other ("multilayer sheet"); two or more layers coextruded together ("coextruded sheet"); two or more coextruded sheets combined with each other; a combination of at least one monolayer sheet and at least one coextruded sheet; and a combination of at least one multilayer sheet and at least one coextruded sheet. In various embodiments of the present invention, the multilayer interlayer comprises at least two polymer layers (e.g., monolayer or coextruded multilayer) disposed in direct contact with each other, each layer comprising a polymer resin. As used herein, the term "resin" refers to the polymer component (e.g., PVB) removed from the mixture resulting from the acid-catalyzed reaction and subsequent neutralization of the polymer precursor. Generally, a plasticizer, such as those discussed further above, is added to the resin to obtain a plasticized polymer. Furthermore, the resin may have other components in addition to the polymer and plasticizer, including, for example, acetates, salts, and alcohols.

[0048]

[0062] While the above recycling steps can result in a recovered PVB having at least some inherent plasticizer (e.g., 3-5 phr of plasticizer), embodiments may require adding additional plasticizer to the PVB before the PVB is used to form a polymer interlayer and / or a laminated glass panel including a polymer interlayer. For example, in some embodiments, an additional amount of 25-50 phr, 25-45 phr, 30-40 phr, or 33-35 phr may be added to the resulting PVB before the polymer interlayer and / or laminated glass panel is produced. In other embodiments, an additional amount of less than 25 phr, or less than 20 phr, or less, or more than 50 phr, or more than 55 phr, or more than 60 phr, or more than 65 phr, or more than 70 phr, or more may be added to the resulting PVB before the polymer interlayer and / or laminated glass panel is produced. Higher or lower amounts of plasticizer may be added as desired depending on the desired properties and application. In high PVOH PVB resins, additional resin may be added to control or reduce the level of plasticizer in the resin.

[0049]

[0063] The recovered PVB resin(s) typically have a molecular weight of greater than 30,000, or less than 500,000, or from about 30,000 to about 500,000 daltons, or from about 500,000 to about 500,000 daltons, or from 100,000 to about 425,000 daltons, as measured by size exclusion chromatography using low angle laser light scattering. As used herein, the term "molecular weight" refers to weight average molecular weight.

[0050]

[0064] Once a sufficient amount of plasticizer has been added to the recycled low PVOH PVB resin, or additional resin has been added to the high PVOH PVB resin (if necessary), it is believed that the polymer interlayer sheet can be manufactured by any suitable process known to those skilled in the art of manufacturing polymer interlayer sheets that can be used in multiple layer panels (such as glass laminates). For example, it is believed that the polymer interlayer sheet can be formed by solution casting, compression molding, injection molding, melt extrusion, melt blowing, or any other means for producing and manufacturing polymer interlayer sheets known to those skilled in the art. Furthermore, in embodiments in which multiple polymer interlayers are utilized, it is believed that these multiple polymer interlayers can be formed by coextrusion, blown film, dip coating, solution coating, blade, paddle, air knife, printing, powder coating, spray coating, or other methods known to those skilled in the art. Any method for producing a polymer interlayer sheet known to those skilled in the art is considered a possible method for producing the polymer interlayer sheets described herein, however, this application will focus on polymer interlayer sheets produced by extrusion and / or coextrusion processes.

[0051]

[0065] In the extrusion process, the thermoplastic resin and plasticizer, including any of the resins and plasticizers described above, are typically premixed and fed into the extrusion device. Additives such as colorants and UV inhibitors (in liquid, powder, or pellet form) may be used and can be mixed into the thermoplastic resin or plasticizer before reaching the extrusion device. These additives are incorporated into the thermoplastic polymer resin, and thus the resulting polymer interlayer sheet, to enhance certain properties of the polymer interlayer sheet and its performance in the final multilayer glass panel product.

[0052]

[0066] In the extrusion device, the particles of thermoplastic raw materials and plasticizers, including resins, plasticizers, and any of the other additives mentioned above, are further mixed and melted to obtain a melt that is generally uniform in temperature and composition. An embodiment of the present invention may provide a melt temperature that is approximately 200°C. When the melt reaches the end of the extrusion device, it is forced into an extrusion die. The extrusion die is the part of the extrusion device that gives the final polymer interlayer sheet product its profile. The die generally has an opening defined by a lip, which has one dimension substantially larger than the perpendicular dimension. The die is generally designed so that the melt flows uniformly from a cylindrical profile emerging from the die to the final profile shape of the product. Multiple shapes can be imparted to the final polymer interlayer sheet by the die, as long as there is a continuous profile. Generally, in the most basic sense, extrusion is a method used to make objects of a fixed cross-sectional profile. This is achieved by pushing or pulling a material through a die of the desired cross-section for the final product.

[0053]

[0067] In some embodiments, a coextrusion method may be utilized. Coextrusion is a method in which multiple layers of polymeric materials are extruded simultaneously. Generally, this type of extrusion utilizes two or more extruders to melt and pump a fixed volume of different thermoplastic melts of different viscosities or other properties through a coextrusion die into a desired final form. For example, the multilayer interlayer of the present invention (e.g., in the form of a three-layer interlayer) may be preferably coextruded using a multi-manifold coextrusion device including a first die manifold, a second die manifold, and a third die manifold. The coextrusion device may be operated by simultaneously extruding the polymer melt from each manifold through the die and out of the opening, and the multilayer interlayer is extruded as a composite of three individual polymer layers. To result in the production of a three-layer interlayer in which the core layer is sandwiched between the skin layers, the polymer melt may flow through the die such that the core layer is disposed between the skin layers. The opening of the die may include a pair of lips located on either side of the opening. Given the placement of the polymer melt, the skin layers may contact the lips. Regardless, the interlayer thickness may be varied by adjusting the distance between the die lips located at the die opening.

[0054]

[0068] In many cases, polymer interlayers having three layers will be used in the manufacture of laminated glass panels. For example, in some embodiments of this application, the improved acoustic damping properties of the soft layer are combined with the mechanical strength of the hard / rigid layer to create a multi-layer interlayer. In these embodiments, a central soft layer is sandwiched between two hard / rigid outer layers. This (hard) / / (soft) / / (rigid) configuration creates a multi-layer interlayer that is easy to handle, can be used in conventional lamination methods, and can be constructed with relatively thin and light layers. The soft core layer is generally characterized by a lower residual hydroxyl content, a higher plasticizer content, and / or a lower glass transition temperature than the relatively hard skin layers.

[0055]

[0069] The following presents a simplified description of how a multi-layer glass panel is typically produced in combination with an interlayer formed according to the above process. First, a multi-manifold coextrusion device can be used to coextrude the multi-layer interlayer, as described above. The device operates by simultaneously extruding the polymer melt from each manifold toward the extrusion orifice. The properties of the layers can be varied by adjusting the die lip properties of the extrusion orifice (e.g., temperature and / or orifice dimensions). Once formed, the interlayer sheet can be placed between two glass substrates, and the excess interlayer is trimmed off from the edges to create an assembly. It is unusual for multiple polymer interlayer sheets or a polymer interlayer sheet with multiple layers (or a combination of both) to be placed inside two glass substrates to create a multi-layer glass panel with multiple polymer interlayers. Air is then removed from the assembly by any applicable process or method known to those skilled in the art; for example, by nip rollers, vacuum bags, or another degassing mechanism. Furthermore, the interlayer is partially pressed to the substrate by any method known to those skilled in the art. In a final step, this preliminary bond is made more permanent by a high temperature and pressure lamination process or any other method known to those skilled in the art, such as, but not limited to, autoclaving, to form the final integral structure.

[0056]

[0070] In view of the above, a multilayer panel includes two sheets of glass, or other applicable substrate, with a polymer interlayer sheet(s) sandwiched therebetween. Multilayer panels are generally produced by placing at least one polymer interlayer sheet between two substrates to create an assembly. FIG. 14 shows a multilayer panel 10 including a pair of glass sheets 12 with a multilayer interlayer sandwiched therebetween. The multilayer interlayer is configured as a three-layer interlayer having three individual polymer interlayer sheets, including a soft core layer 14 and two relatively hard skin layers 16 disposed on either side of the core layer 14. Such glass panels incorporating such a three-layer structure may have better acoustic properties due to the sound reduction provided by the soft core layer, as discussed above.

[0057]

[0071] In some embodiments, the intermediate layer (e.g., the core layer 14 and the skin layer 16) have a generally constant or uniform thickness over the length of the intermediate layer (see, e.g., FIG. 14). However, in alternative embodiments, the intermediate layer may have at least one region of non-uniform thickness, as shown in FIG. 15. For example, the intermediate layer, including the core layer 14 and the skin layer 16, may be wedge-shaped such that the thickness of the intermediate layer varies (e.g., linearly) over the length of the intermediate layer. In some such embodiments, the thickness of the intermediate layer may vary due to a change in the thickness of the core layer 14 (i.e., the skin layer 16 has a generally constant thickness). Alternatively, the thickness of the intermediate layer may vary due to a change in the thickness of the skin layer 16 (i.e., the core layer 14 has a generally constant thickness). In a further alternative, the thickness of the intermediate layer may vary due to a change in the thickness of both the core layer 14 and the skin layer 16. In a further embodiment (not shown), one or more layers may increase in thickness across the width of the interlayer while one or more layers simultaneously decrease in thickness while maintaining an interlayer having at least one region of non-uniform thickness, such as a wedge-shaped interlayer. Such glass panels incorporating such three layers may have better acoustic properties due to the sound reduction provided by the soft core layer, as discussed above. Furthermore, due to the non-uniform thickness of the three layers, the glass panels may provide properties beneficial for use in head-up displays ("HUDs") by reducing undesirable image projection defects (e.g., reducing ghost images).

[0058]

[0072] Although disclosed in conjunction with the description of specific embodiments, including what are presently considered to be preferred embodiments, the detailed description is intended to be illustrative and should not be understood as limiting the scope of the disclosure. As will be appreciated by those skilled in the art, embodiments other than those specifically described herein are encompassed by the present invention. Modifications and variations of the described embodiments can be made without departing from the spirit and scope of the present invention.

[0059]

[0073] It will be further understood that any of the ranges, values, or properties set forth for any single component of the present disclosure can be used interchangeably with any of the ranges, values, or properties set forth for any of the other components of the disclosure, where applicable, to make embodiments having the stated values ​​for each of the components as set forth throughout this specification. For example, a polymer layer can be formed that includes a plasticizer content in any of the ranges set forth for residual hydroxyl content in addition to any of the ranges set forth, and many variations can be made, as needed, that are within the scope of the present invention but would be burdensome to list. EXAMPLES

[0060] material

[0074] The following materials were used in the examples below.

[0061]

[0075] PVB flake (also called PVB sheet) is a three-ply PVB sheet that has been cut into smaller flakes or pieces. The PVB flake used contains about 10-15 wt.% low PVOH PVB resin and about 85-90 wt.% high PVOH PVB resin on a resin only basis (excluding any plasticizers in the flake or sheet). In many examples, the PVB flake can be recycled Saflex® Q Series Acoustic PVB sheet from Eastman Chemical Company that has been cut or chopped into smaller flakes.

[0062]

[0076] PVB pellets are pellets that contain PVB flakes (including Saflex® Q Series Acoustic PVB) that have been run through an extruder and pelletized. Typically, the pellets contain small domains dispersed in a matrix of high PVOH PVB (skin) resin due to the low content of low PVOH PVB (core) resin in the pellets.

[0063]

[0077] Recycled PVB 1 is a first sample of post-consumer PVB sheet with unknown or unmeasured contents purchased from Recyverre, Inc. This material is chopped, shredded, or ground to form small pieces or flakes of material.

[0064]

[0078] Recycled PVB2 is a second sample of post-consumer PVB sheet with unknown or unmeasured contents purchased from Recyverre, Inc. This material is chopped, shredded, or ground to form small pieces or flakes of material.

[0065] Examples to Illustrate Solubility in Alcohol / Water Mixtures

[0079] Gradient polymer elution chromatography (GPEC) is a technique that can provide information about the composition of copolymers or terpolymers and the concentration of the polymer components, including the amount of plasticizer. The GPEC method involves first dissolving the polymer (i.e., PVB) in a good solvent, or using an extractant if the concentration of the extracted component is of interest. The dissolved sample or solution is injected onto the column under solvent conditions that cause the polymer to precipitate. The mobile phase is then changed to a gradient, which causes the polymer to elute as it redissolves. In the case of PVB, the main separation mechanism is believed to be the solubility of the PVB fraction in the mobile phase, so that the plasticizer elutes first due to its high solubility and low molecular weight in the solvent. There is also a separation mechanism due to the interaction of PVB with the column packing. There can be multiple factors that affect the separation, but the composition of the copolymer is believed to be the largest factor. The GPEC method can be used to determine the composition of the polymer, or in this case, the concentration of the resin and plasticizer in the sample.

[0066]

[0080] Experimental conditions and equipment used for GPEC testing: i.Thermo Scientific Dionex Ultimate 3000 Series HPLC ii. Corona Veo Charged Aerosol Detector-Evaporator (low setting) iii. Column: Supelco Discovery C18, 150mm, 4.6mm, 5 micron, 180A.

[0067] iv. Column temperature: 30°C v. Injection volume: 10 microliters vi. Gradient (flow rate: 1 ml / min)

[0068] [Table 1]

[0069]

[0081] GPEC sample preparation: PVB interlayer solid samples were dissolved in glacial acetic acid and the extract was used as is (approximately 0.05-0.5 g in 10 ml acetic acid). The solution was left to dissolve overnight at room temperature. Sample types included extracts in alcohol / water mixtures, plasticizer solutions, plasticizer / resin gels, and pellet, resin, or sheet samples.

[0070]

[0082] GPEC quantification: using the following formula: Pz / R = (a * area of ​​plasticizer) / (area of ​​resin) (where a is the response factor) is used to estimate the relative concentrations of resin (R) and plasticizer (Pz) based on relative area percentages. Estimate the relative concentrations of skin and core resins based on relative area percentages: % Core Resin = (Core Resin Area) * 100 / (Core Resin Area + Skin Resin Area) % Skin Resin = (Skin Resin Area) * 100 / (Core Resin Area + Skin Resin Area)

[0083] The weight percent of resin in a sample is determined by analysis of a solution of known resin concentration and by determining a single point response factor or by linear calibration.

[0071] Examples 1 to 8

[0084] GPEC solubility tests were performed by placing 0.1 g of recycled PVB flakes or PVB pellets into a 20 mL scintillation vial containing 15 mL of the solvent mixture to form samples 1-8. The recycled PVB flakes had a three-layer structure, with the skin layer being a high PVOH PVB resin containing about 18.7 wt.% PVOH and the core layer being a low PVOH PVB resin containing about 10.5% PVOH (this is about 11 wt.% low PVOH PVB resin and about 89 wt.% high PVOH PVB resin based on resin only, or about 7 wt.% low PVOH PVB resin, about 63 wt.% high PVOH PVB resin, and about 30 wt.% plasticizer based on total weight). Both the core and skin layers were plasticized with triethylene glycol di-(2-ethylhexanoate) (3-GEH). The vials were capped and then placed on a shaker for 12 hours before sampling. Each extract was analyzed using GPEC. Note that the extract was filtered through a 0.5 micron filter regardless of its appearance (clear or cloudy) and the filtered sample must be clear for injection.

[0072]

[0085] For each alcohol system, the % water at the solubility cutoff value for low PVOH resins, above which resins having approximately 10.5 wt.% PVOH were no longer detectable by the GPEC method, was determined as follows: Ethanol: greater than about 20% water by weight; Methanol: greater than about 4% water by weight.

[0073]

[0086] For each alcohol system, the % water at the high PVOH resin solubility cutoff value above which the high PVOH resin was no longer detectable by the GPEC method was determined as follows: Ethanol: greater than about 35% water by weight; Methanol: greater than about 20% water by weight.

[0074]

[0087] Table 1 and Figures 2-4 show data for the extractables of PVB for Samples 1-8 obtained using various solvent mixtures (with various levels of alcohol in water) that were analyzed using GPEC. Specifically, Figure 2 shows GPEC chromatograms of recycled PVB in mixtures of ethanol and water. The PVB mixture dissolved in ethanol containing about 9 wt.% water shows that both resins are soluble in the mixture (top). As the water content in ethanol was increased to about 16 wt.% water, the low PVOH PVB resin became less soluble but was still detectable (middle). In ethanol containing about 20 wt.% water, only a small amount of the low PVOH resin was detected (bottom).

[0075]

[0088] Figure 3 shows the GPEC chromatograms of recycled PVB in aqueous methanol. The interphase mixture dissolved in pure methanol (no added water) shows that some low PVOH resin is still detectable (top). With about 9.5 wt.% water in methanol, the solubility of the high PVOH PVB resin is low relative to the plasticizer (middle). Methanol with about 4.9 wt.% water has only a small amount of low PVOH PVB resin and good solubility of the high PVOH PVB resin (bottom).

[0076]

[0089] Figure 4 shows GPEC chromatograms of recycled PVB in mixtures of isopropanol and water. Both 100% isopropanol (top) and isopropanol with 32 wt.% water (bottom) show low solubility of high PVOH PVB relative to the plasticizer.

[0077]

[0090] The area percentages from the chromatograms in Figures 2-4 are summarized in Table 1. Measurements of the material are performed on the high PVOH PVB (extracted or dissolved portion).

[0078] [Table 2]

[0079]

[0091] The data in Figures 2-4 and Table 1 show the percentage of low and high PVOH in each resin. Example 1 is a control example. Using about 9 wt.% water in ethanol did not achieve selective dissolution of the low PVOH PVB resin. Examples 2, 7, and 8 show that only using 16 wt.% water in ethanol (Example 2), or isopropanol (containing 0% or 32% water in Examples 7 and 8, respectively) dissolved all of the high PVOH PVB resin and some of the low PVOH PVB resin in the extract. Examples 3, 4, 5, and 6 selectively dissolved the high PVOH PVB resin (relative to the low PVOH PVB resin) in the extract using selective dissolution with 20 wt.% water in ethanol (Example 3) or 0-9.5 wt.% water in methanol (Examples 4, 5, and 6). In other words, Examples 3, 4, 5, and 6 selectively dissolved the high PVOH PVB resin relative to the low PVOH PVB resin, while Examples 2, 7, and 8 were not as selective as Examples 3, 4, 5, and 6.

[0080] Dissolution / filtration method using pelletized material

[0092] Based on the solubility considerations above, a separation process using selective dissolution followed by filtration, such as that described in the flow chart of FIG. 5, was tested in Examples 9-16 below for both post-industrial and post-consumer recycled PVB interlayers. The dissolution and filtration method is more suitable for materials with a well-dispersed composition in the feed material, such as pelletized recycled multilayer PVB. Premixed materials in PVB pellets resulted in a visibly cloudy solution in which the domains of undissolved low PVOH PVB (core) resin were very small and remained in suspension. Mixtures containing 10% recycled PVB pellets in each solvent combination (shown below) were stirred at 50° C. for 2 hours to obtain viscous, cloudy suspensions. These visibly cloudy suspensions were designated the “before” samples in Table 2. An aliquot portion of the mixture was then sieved through a 1 mm filter to collect large resin chips and then further filtered using a laboratory 10 T filter (ErtelAlsop) with M-503 filter media. The resulting samples were designated the “after” samples in Table 2. Both the unfiltered (before) and filtered (after) samples were further dried in a 50° C. oven for 2 hours before being pressed into a sheet having a thickness of about 760 microns and laminated between two pieces of glass for haze measurement. The haze of the resulting material after removal of the solvent from the combined filtrate (i.e., dried) reflected the varying degrees of undissolved material that passed through during filtration (Table 2). A spectrophotometer was used to measure haze on the laminated, dried material using techniques known to those skilled in the art and as described above.

[0081] Example 9

[0093] 450 parts of ethanol containing 20% ​​water was placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB pellets were added and stirred at 50°C for 2 hours. The resulting mixture was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 50°C for 2 hours before being pressed into a sheet with a thickness of 760 microns and laminated between two pieces of glass for haze measurement as a control. The haze value was 51.6.

[0082] Example 10

[0094] 450 parts of ethanol containing 20% ​​water was placed in a 1-liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB pellets were added and stirred at 50° C. for 2 hours. The resulting mixture was then filtered at 60 psi using a laboratory 10 T filter (ErtelAlsop) with M-503 filter media. The viscous solution filtrate was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 50° C. for 2 hours, after which it was pressed into a sheet with a thickness of 760 microns and laminated between two pieces of glass for haze measurement. The haze value was 1.9.

[0083] Example 11

[0095] 450 parts of methanol containing 4% water was placed in a 1-liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB pellets were added and stirred at 50° C. for 2 hours. The resulting mixture was then filtered at 60 psi using a laboratory 10 T filter (ErtelAlsop) with M-503 filter media. The viscous solution filtrate was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 50° C. for 2 hours, after which it was pressed into a sheet with a thickness of 760 microns and laminated between two pieces of clear glass for haze measurement. The haze value was 17.7.

[0084] Example 12

[0096] 450 parts of ethanol containing 20% ​​water was placed in a 1-liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB pellets were added and stirred at room temperature for 12 hours. The resulting mixture was then filtered at 60 psi using a laboratory 10 T filter (ErtelAlsop) with M-503 filter media. The viscous solution filtrate was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 50° C. for 2 hours, after which it was pressed into a sheet with a thickness of 760 microns and laminated between two pieces of glass for haze measurement. The haze value was 11.8.

[0085]

[0097] Table 2 shows the types of PVB materials, solvents, and haze values ​​used in Examples 9 to 12 above.

[0086] [Table 3]

[0087]

[0098] Table 2 shows that there is a significant reduction in haze from the original sample (before) to the recovered sample (after) where the low PVOH PVB has been removed by the process of the present invention. A comparison of Examples 9-10, 11, and 12 shows that use of the process of the present invention significantly reduces haze when using solvents of either ethanol and water or methanol and water.

[0088]

[0099] Samples before and after filtration were also analyzed using GPEC as shown in Figures 6 and 7. In some cases, passage of undissolved resin was observable as seen in the final filtrate in Figure 6. Figure 6 shows a GPEC chromatogram of a suspension sample after dissolving 10% PVB pellets of Example 11 with methanol containing 4 wt.% water (top). The starting filtrate sample showed no detectable low PVOH PVB resin (middle). The final filtrate sample showed that some low PVOH PVB resin passed through the filter media (bottom). Figure 7 shows a GPEC chromatogram of a suspension sample after dissolving 10% PVB pellets of Example 10 in ethanol containing 20 wt.% water (top) and the combined filtrate (bottom). The entire filtered material was combined.

[0089] Extraction / filtration method using three interlayers

[0100] The extraction method is more suitable for feeds that are still in layered form, such as ground multi-layer interlayer material (i.e., PVB flakes that are pieces of multi-layer material such as sheets that have been chopped or cut into small pieces), where the undissolved material can maintain a consistent form and size during the operation and can be easily separated from the extract using a coarse screen. The general process is illustrated in Figure 8. The extraction part or step is typically carried out at ambient conditions and generally involves at least three extraction steps for good separation. The extract and undissolved resin can be easily separated using a very coarse screen.

[0090] Example 13

[0101] 800 parts of water were placed in a 1-liter three-neck jacketed glass reactor. To the stirred mixture, 0.5 parts of citric acid, 4 parts of sulfuric acid, and 200 parts of 1.27 centimeter (1 / 2 inch) flakes cut from Recycle PVB1 were added and stirred at 50° C. for 1 hour. The resulting flakes were poured into a filter with a 1 mm screen and rinsed with tap water. The washed flakes were poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in a 50° C. oven for 2 hours for further use.

[0091] Example 14

[0102] 450 parts of ethanol containing 20% ​​water were placed in a 1 liter three-neck jacketed glass reactor. 50 parts of dried Recycle PVB1 flakes from Example 13 were added to the stirred mixture and stirred at 50°C for 2 hours. The resulting mixture was divided into two parts. One part was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 50°C for 2 hours, after which it was pressed into a sheet with a thickness of 760 microns and laminated between two pieces of glass for haze measurement as a control (previous sample). The second part was filtered at 60 psi using a laboratory 10 T filter (ErtelAlsop) with M-503 filter media. The viscous solution filtrate was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 50°C for 2 hours, after which it was pressed into a sheet with a thickness of 760 microns and laminated between two pieces of glass for haze measurement. The haze value was 13.7.

[0092] Example 15

[0103] The above process in Example 13 was repeated using 1.27 centimeter (½ inch) flakes cut from Recycle PVB2 instead of Recycle PVB1. The resulting material was dried for subsequent use in Example 16.

[0093] Example 16

[0104] The above process in Example 14 was repeated using the material obtained in Example 15.

[0094]

[0105] Table 3 below shows the PVB materials, solvents, and haze values ​​used for Examples 13-16 above.

[0095] [Table 4]

[0096]

[0106] Table 3 shows that there is a significant reduction in haze from the original sample (before) to the recovered sample (after) where the low PVOH PVB has been removed by the process of the present invention. Comparing Example 13 to Example 14, the haze was reduced from 28.5% to 13.7% using the process of the present invention. Similarly, comparing Examples 15 and 16, the haze was reduced from 11.7% to 3.4%.

[0097] Example 17

[0107] 450 parts of 190 proof ethanol (approximately 9 wt.% water in ethanol) was placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB flake (1.27 centimeter (1 / 2 inch) pieces) were added and stirred for 12 hours at ambient temperature (approximately 22-23°C). The resulting mixture was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in a 40°C oven for 12 hours before being pressed into a sheet having a thickness of 760 microns and laminated between two pieces of glass to give a haze of 61.3%. GPEC analysis showed the resin composition of the material to be approximately 89 wt.% high PVOH (skin) resin and 11 wt.%.

[0098] Example 18

[0108] 450 parts of ethanol containing 20% ​​water was placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB flakes (cut into 1 / 2 inch pieces but 8 mesh or better) were added and stirred at ambient temperature (approximately 22-23°C) for 3 hours. The resulting mixture was filtered through a 1 mm screen strainer. The filtrate was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 40°C for 12 hours to give 38.42 parts of PVB with 46.9 phr of plasticizer. The resulting PVB was pressed into a sheet having a thickness of 760 microns and laminated between two pieces of clear glass to give an interlayer with a haze of 4.2%. After drying, the material on the screen was 12 parts, and GPEC analysis showed the resin composition of the material on the screen to be about 31 wt.% high PVOH (skin) resin and 69 wt.% low PVOH (core) resin with 25 phr plasticizer. Most of the high PVOH material had been removed, and the filtered material (Example 18) had significantly less high PVOH PVB resin than the starting material of Example 17. Additionally, the resulting material of Example 18 had significantly reduced haze levels.

[0099] Example 19

[0109] 50 parts of PVB flakes were added to 450 parts of ethanol containing 20 wt.% water. The mixture was stirred for 4 hours and the supernatant was decanted. 450 parts of fresh solvent (20 wt.% water in ethanol) was added to the remaining flakes and stirred for 4 hours. The above process was repeated one more time. The extracted flakes yielded 3.8 parts of dry resin after evaporation and the combined extracts after evaporation yielded 46 parts of high PVOH resin and plasticizer mixture, indicating a very high separation yield using this technique and ethanol water mixture. Longer stirring dissolves more of the high PVOH PVB resin in the separation and removal from the low PVOH PVB resin.

[0100]

[0110] Centrifugation can also be used to separate the low PVOH PVB resin from the solution. First, the interlayer is treated with a solvent system that dissolves only one of the two resins in the mixture, and then the resulting suspension is centrifuged to facilitate separation. Complete or partial removal of one component can help reduce haze in recycling.

[0101] Example 20

[0111] The PVB pellets were treated with 165-174 proof alcohol (methanol containing approximately 5 wt.% water). The mixture was stirred for several hours to obtain a viscous suspension. Centrifugation of the suspension yielded a supernatant and a precipitate. The supernatant consisted primarily of high PVOH PVB (skin) resin and plasticizers. The precipitate was more abundant in low PVOH PVB (core) resin. Figure 9 shows GPEC chromatograms of the starting PVB pellets (top), the supernatant (middle), and the precipitated material (bottom). Centrifugation of the 5% wt. PVB Q material in 170 proof alcohol resulted in approximately a 60% reduction in the low PVOH PVB (core) resin in the supernatant, and the precipitated material is primarily low PVOH PVB (core) resin.

[0102] Example 21

[0112] When PVB pellets are used as the feed, the separation of the high and low PVOH PVB resins is not as clean as when chopped PVB flakes are used due to the fact that in the PVB pellets the two resins (core and skin) are premixed and the undissolved material forms much finer suspended particles that are more difficult to separate using centrifugation. Figure 10 shows GPEC chromatograms of the PVB pellets supernatant (top) and the PVB flakes supernatant (bottom), both after centrifugation. Centrifugation of 10% wt. PVB pellets in 170 proof ethanol shows a 36% reduction in the low PVOH PVB (core) resin in the supernatant. In comparison, centrifugation of 10% wt. PVB flakes in 170 proof ethanol shows a very small amount of the low PVOH PVB (core) resin remaining in the supernatant.

[0103] Example 22

[0113] In suspensions made from extracted PVB pellets, as the percent of total solids (TS%) increases, the separation efficiency between the supernatant and suspended matter decreases. In Figure 11, after centrifugation, the GPEC chromatogram of the supernatant of 10% PVB pellets in 165 proof ethanol (top) shows a 36% reduction in low PVOH PVB (core) resin. After centrifugation, the supernatant of 5% PVB pellets in 170 proof ethanol (bottom) shows a 60% reduction in low PVOH PVB (core) resin. The reduction or removal of low PVOH PVB resin nearly doubles as the total solids level decreases from 10% to 5%.

[0104] Example 23

[0114] 450 parts of ethanol containing 20% ​​water was placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 25 parts of PVB pellets were added and stirred for 3 hours at ambient temperature (approximately 22-23°C). The resulting mixture was centrifuged at 4200 rpm for 40 minutes. The resulting supernatant and precipitated material were analyzed using GPEC. The supernatant layer showed a 60% reduction in low PVOH PVB (core) resin (see Figure 12, top). The above centrifugation procedure was repeated and the supernatant showed an 82% reduction in low PVOH PVB (core) resin by GPEC (see Figure 12, bottom).

[0105] Example 24

[0115] 450 parts of ethanol containing 24% water was placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB pellets were added and stirred for 3 hours at ambient temperature (approximately 22-23°C). The resulting mixture was centrifuged. The resulting supernatant and precipitated material were analyzed using GPEC. The supernatant layer showed a 36% reduction in low PVOH PVB (core) resin (see Figure 13, top). The above centrifugation procedure was repeated and the supernatant showed a 53% reduction in low PVOH PVB (core) resin by GPEC (see Figure 13, bottom).

[0106]

[0116] Regardless of the total solids level, further separation can be achieved by additional centrifugation. For example, as discussed above and shown in Figures 12 and 13, a second centrifugation step increases the reduction of low PVOH PVB (core) resin from 60 to 82% for material with 5% starting total solids and from 36 to 53% for 10% starting total solids (Examples 23 and 24, respectively), suggesting that multiple or sequential centrifugations can further improve separation of high and low PVOH PVB resins.

[0107] Example 25

[0117] 450 parts of ethanol containing 20% ​​water was placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB flakes, 8 mesh or finer, were added and stirred at ambient temperature (approximately 22-23°C) for 3 hours. The resulting mixture was centrifuged. The supernatant was poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 40°C for 12 hours to give 41.5 parts of PVB with 45.5 phr of plasticizer. The material was pressed into a sheet having a thickness of approximately 760 rons, laminated between two pieces of clear glass, and tested for haze. The haze measured was 3.6%. The combined precipitated material was 8 parts after drying and GPEC analysis showed a resin composition of 33% high PVOH PVB (skin) resin and 67% low PVOH PVB (core) resin with 22.1 phr of plasticizer.

[0108] Example 26

[0118] 450 parts of ethanol containing 9% water were placed in a 1 liter three-neck jacketed glass reactor. To the stirred mixture, 50 parts of PVB flakes were added and stirred for 3 hours at ambient temperature (approximately 22-23°C). The resulting mixture was not centrifuged, but poured into an aluminum tray and dried by evaporation in a fume hood until no weight loss was detectable. The material was then further dried in an oven at 40°C for 12 hours and then pressed into a sheet having a thickness of approximately 760 microns. The sheet was then laminated between two pieces of clear glass and the haze was measured. The resulting haze was 51.6%.

[0109]

[0119] The above shows that dissolution can be combined with centrifugation to provide an alternative method for separating high PVOH and low PVOH PVB resins.

[0110]

[0120] The present invention and its preferred embodiments will now be further described with reference to numbered items 1-57.

[0111]

[0121] Item 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) providing a solvent to a regeneration system; (b) adding recycled PVB to a solvent and stirring to form a PVB mixture, the PVB mixture comprising a liquid portion comprising dissolved high PVOH PVB resin and plasticizer and a solid portion comprising low PVOH PVB solids; (c) filtering the PVB mixture to remove low PVOH PVB solids; A method comprising:

[0112]

[0122] Item 2. The method of item 1, wherein the removed low PVOH PVB solids comprise residual high PVOH PVB resin and plasticizer, further comprising the step (d) of separating the residual high PVOH PVB resin and plasticizer from the low PVOH PVB solids.

[0113]

[0123] Item 3. The method of item 2, wherein the separating step (d) comprises washing the low PVOH PVB resin.

[0114]

[0124] Item 4. The method of item 2, wherein the separating step (d) comprises adding a solvent to the low PVOH PVB resin to further dissolve and remove the high PVOH PVB resin and the plasticizer.

[0115]

[0125] Item 5. The method of item 1, further comprising the step (e) of measuring the level of plasticizer and high PVOH PVB in the low PVOH PVB solids.

[0116]

[0126] Item 6. The method of item 5, further comprising repeating steps (a) to (e).

[0117]

[0127] Item 7. The method of item 6, wherein at least 80% (85%, 90%, 95%, 96%, 97%, 98%, 99%, or more) of the high PVOH PVB resin is removed from the recycled PVB.

[0118]

[0128] Item 8. The method of Item 1, wherein step (b) comprises a step of stirring at a temperature of about 5° C. to about 60° C. (5° C. to about 50° C., 5° C. to about 40° C., 5° C. to about 30° C., 5° C. to about 20° C., or 5° C. to about 10° C.).

[0119]

[0129] Item 9. The method of item 1, wherein the recycled PVB is in the form of PVB pellets.

[0120]

[0130] Item 10. The method of item 1, wherein the recycled PVB is in the form of PVB flakes, or pieces of PVB film or sheet.

[0121]

[0131] Item 11. The method of item 1, wherein the recycled PVB is in the form of PVB flakes, or PVB film or sheet pieces and PVB pellets.

[0122]

[0132] Item 12. The method of item 1, wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a batch reactor system.

[0123]

[0133] Item 13. The method of item 1, wherein the solvent added in step (a) comprises a mixture of water and an alcohol.

[0124]

[0134] Item 14. The method of item 13, wherein the alcohol is ethanol, methanol, or isopropanol, or a mixture of two or more alcohols.

[0125]

[0135] Item 15. The method of item 14, wherein the alcohol is ethanol and the water is present in an amount of about 16 weight percent to about 24 weight percent.

[0126]

[0136] Item 16. The method of item 14, wherein the alcohol is ethanol and the water is present in an amount of about 20 percent by weight to about 24 percent by weight.

[0127]

[0137] Item 17. The method of item 14, wherein the alcohol is methanol and water is present in an amount of about 0 weight percent to about 9.5 weight percent.

[0128]

[0138] Item 18. The method of item 9, wherein the recycled PVB has a diameter of about 2 to about 20 millimeters.

[0129]

[0139] Item 19. The method of item 1, wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a continuous regeneration system.

[0130]

[0140] Item 20. The method of item 19, wherein the continuous regeneration system is a continuous stirred tank reactor.

[0131]

[0141] Item 21. The method of item 1, wherein the recycled PVB is added to the solvent in an amount of at least 1 wt.% (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, or more).

[0132]

[0142] Item 22. A low PVOH PVB resin formed by the method of any of items 1 to 21.

[0133]

[0143] Item 23. A resin layer comprising the low PVOH PVB resin of Item 22.

[0134]

[0144] Item 24. An intermediate layer comprising the resin layer of Item 23.

[0135]

[0145] Item 25. The intermediate layer of item 24, further comprising a second resin layer.

[0136]

[0146] Item 26. The intermediate layer of item 23, wherein the resin layer is a core layer, and the intermediate layer further comprises a second resin layer and a third resin layer, the core layer being between the second resin layer and the third resin layer.

[0137]

[0147] Item 27. A composition comprising the low PVOH PVB resin of item 22.

[0138]

[0148] Item 28. A laminate comprising a first substrate, the intermediate layer of item 24, and a second substrate, wherein the intermediate layer is between the first substrate and the second substrate.

[0139]

[0149] Item 29. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) providing a solvent to a regeneration system; (b) adding recycled PVB to a solvent and stirring to form a PVB mixture, the PVB mixture comprising a liquid portion comprising dissolved high PVOH PVB resin and plasticizer and a solid portion comprising low PVOH PVB solids; (c) filtering the PVB mixture to remove low PVOH PVB solids, the removed low PVOH solids comprising residual high PVOH PVB resin and plasticizer; A method comprising:

[0140]

[0150] Item 30. The method of item 29, wherein the low PVOH solids include less than 20% (15%, 10%, 5%, 4%, 3%, 2%, 1%) high PVOH PVB resin derived from recycled PVB.

[0141]

[0151] Item 31. The method of item 28, further comprising the step (d) of separating the residual high PVOH PVB resin and plasticizer from the low PVOH PVB solids.

[0142]

[0152] Item 32. The method of item 31, wherein the separating step (d) includes washing the low PVOH PVB resin.

[0143]

[0153] Item 33. The method of item 31, wherein the separating step (d) comprises adding a solvent to the low PVOH PVB resin to further dissolve and remove the high PVOH PVB resin and the plasticizer.

[0144]

[0154] Item 34. The method of item 29, further comprising the step (e) of measuring the level of plasticizer and high PVOH PVB in the low PVOH PVB solids.

[0145]

[0155] Item 35. The method of Item 34, further comprising repeating steps (a) to (e).

[0146]

[0156] Item 36. The method of item 35, wherein at least 80% (85%, 90%, 95%, 96%, 97%, 98%, 99%, or more) of the high PVOH PVB resin is removed from the recycled PVB.

[0147]

[0157] Item 37. The method of Item 29, wherein step (b) comprises a step of stirring at a temperature of about 5° C. to about 60° C. (5° C. to about 50° C., 5° C. to about 40° C., 5° C. to about 30° C., 5° C. to about 20° C., or 5° C. to about 10° C.).

[0148]

[0158] Item 38. The method of item 29, wherein the recycled PVB is in the form of PVB pellets.

[0149]

[0159] Item 39. The method of item 29, wherein the recycled PVB is in the form of PVB flakes, or pieces of PVB film or sheet.

[0150]

[0160] Item 40. The method of item 29, wherein the recycled PVB is in the form of PVB flakes, or PVB film or sheet pieces and PVB pellets.

[0151]

[0161] Item 41. The method of item 29, wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a batch reactor system.

[0152]

[0162] Item 42. The method of item 29, wherein the solvent added in step (a) comprises a mixture of water and an alcohol.

[0153]

[0163] Item 43. The method of item 42, wherein the alcohol is ethanol, methanol, or isopropanol, or a mixture of two or more alcohols.

[0154]

[0164] Item 44. The method of item 43, wherein the alcohol is ethanol and the water is present in an amount of about 16 weight percent to about 24 weight percent.

[0155]

[0165] Item 45. The method of item 43, wherein the alcohol is ethanol and the water is present in an amount of about 20 weight percent to about 24 weight percent.

[0156]

[0166] Item 46. The method of item 43, wherein the alcohol is methanol and water is present in an amount of about 0 weight percent to about 9.5 weight percent.

[0157]

[0167] Item 47. The method of item 39, wherein the recycled PVB has a diameter of about 2 to about 20 millimeters.

[0158]

[0168] Item 48. The method of item 29, wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a continuous regeneration system.

[0159]

[0169] Item 49. The method of item 48, wherein the continuous regeneration system is a continuous stirred tank reactor.

[0160]

[0170] Item 50. The method of item 29, wherein the recycled PVB is added to the solvent in an amount of at least 1 wt.% (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, or more).

[0161]

[0171] Item 51. A low PVOH PVB resin formed by the method of any of items 1 to 50.

[0162]

[0172] Item 52. A resin layer comprising the low PVOH PVB resin of Item 48.

[0163]

[0173] Item 53. An intermediate layer comprising the resin layer of Item 49.

[0164]

[0174] Item 54. The intermediate layer of item 53, further comprising a second resin layer.

[0165]

[0175] Item 55. The intermediate layer of item 52, wherein the resin layer is a core layer, and the intermediate layer further comprises a second resin layer and a third resin layer, the core layer being between the second resin layer and the third resin layer.

[0166]

[0176] Item 56. A composition comprising the low PVOH PVB resin of item 51.

[0167]

[0177] Item 57. A laminate comprising a first substrate, the intermediate layer of item 53, and a second substrate, wherein the intermediate layer is between the first substrate and the second substrate.

Claims

1. 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) providing a solvent to a regeneration system; (b) adding recycled PVB to a solvent and stirring to form a PVB mixture, the PVB mixture comprising a liquid portion comprising dissolved high PVOH PVB resin and plasticizer and a solid portion comprising low PVOH PVB solids; (c) filtering the PVB mixture to remove low PVOH PVB solids; A method comprising:

2. 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) providing a solvent to a regeneration system; (b) adding recycled PVB to a solvent and stirring to form a PVB mixture, the PVB mixture comprising a liquid portion comprising dissolved high PVOH PVB resin and plasticizer and a solid portion comprising low PVOH PVB solids; (c) filtering the PVB mixture to remove low-PVOH PVB solids, the removed low-PVOH solids comprising residual high-PVOH PVB resin and plasticizer. method.

3. 3. The method of claim 1 or 2, wherein the removed low PVOH PVB solids comprise residual high PVOH PVB resin and plasticizer, and further comprising step (d) separating the residual high PVOH PVB resin and plasticizer from the low PVOH PVB solids.

4. 4. The method of claim 3, wherein the separating step (d) comprises washing the low PVOH PVB resin, or the separating step (d) comprises adding a solvent to the low PVOH PVB resin to further dissolve and remove the high PVOH PVB resin and plasticizer.

5. 3. The method of claim 1 or 2, further comprising step (e) measuring the level of plasticizer and high PVOH PVB in the low PVOH PVB solids.

6. The method of claim 5 further comprising repeating steps (a) through (e).

7. 3. The method of claim 1 or 2, wherein at least 80% (85%, 90%, 95%, 96%, 97%, 98%, 99%, or more) of the high PVOH PVB resin is removed from the recycled PVB.

8. 3. The method of claim 1 or 2, wherein step (b) comprises stirring at a temperature of from about 5°C to about 60°C (5°C to about 50°C, 5°C to about 40°C, 5°C to about 30°C, 5°C to about 20°C, 5°C to about 10°C).

9. 3. The method of claim 1 or 2, wherein the recycled PVB is in the form of PVB pellets, or the recycled PVB is in the form of PVB flakes, or PVB film or sheet pieces, or the recycled PVB is in the form of PVB flakes, or PVB film or sheet pieces and PVB pellets, or the recycled PVB has a diameter of about 2 to about 20 millimeters.

10. 3. The method of claim 1 or 2, wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a batch reactor system.

11. 3. The method of claim 1 or 2, wherein the solvent added in step (a) comprises a mixture of water and an alcohol, or wherein the solvent added in step (a) comprises a mixture of water and an alcohol, wherein the alcohol is ethanol, methanol, or isopropanol, or a mixture of two or more alcohols, or wherein the solvent added in step (a) comprises a mixture of water and an alcohol, wherein the alcohol is ethanol and water is present in an amount of about 16 weight percent to about 24 weight percent, or about 20 weight percent to about 24 weight percent, or wherein the solvent added in step (a) comprises a mixture of water and an alcohol, wherein the alcohol is methanol and water is present in an amount of about 0 weight percent to about 9.5 weight percent.

12. 3. The method of claim 1 or 2, wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a continuous regeneration system, or wherein the regeneration system to which the recycled PVB is supplied in step (a) comprises a continuous regeneration system, and the continuous regeneration system is a continuous stirred tank reactor.

13. 3. The method of claim 1 or 2, wherein the recycled PVB is added to the solvent in an amount of at least 1 wt. % (5 wt. %, 10 wt. %, 15 wt. %, 20 wt. %, or more).

14. 3. A low PVOH PVB resin formed by the method of claim 1 or 2.

15. A resin layer comprising the low PVOH PVB resin of claim 14.

16. An intermediate layer comprising the resin layer of claim 15.

17. 17. The intermediate layer of claim 16, further comprising a second resin layer, or wherein the resin layer is a core layer and the intermediate layer further comprises a second resin layer and a third resin layer, the core layer being between the second resin layer and the third resin layer.

18. 15. A composition comprising the low PVOH PVB resin of claim 14.

19. 17. A laminate comprising a first substrate, the intermediate layer of claim 16, and a second substrate, wherein the intermediate layer is between the first substrate and the second substrate.

Images