Recovery of poly(vinyl butyral) polymer

Abstract

A method for recovering poly(vinyl butyral) (PVB). The method includes mixing a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition. The PVB feed composition includes at least two different PVB-containing compositions. An additional step includes determining a residual polyvinyl alcohol (PVOH) content of the equilibrated PVB-containing composition. A further step includes adjusting the amount of butyraldehyde used in the mixing step based on the determined residual PVOH content.

Description

[Technical field]

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

[0002]

[0002] Laminated glass panels, such as automobile windshields and architectural safety glass, are typically composed of two sheets of glass laminated together with a layer of plasticized polymer sandwiched between them. Poly(vinyl butyral) ("PVB") is a common polymer that typically constitutes the major component in the majority of polymer interlayers in automobile windshields and architectural safety glass. Generally, PVB resins are produced by a synthetic process that begins with the separation of ethane from natural gas or directly from an oil 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 poly(vinyl acetate). The poly(vinyl acetate) is hydrolyzed to poly(vinyl alcohol), which is then reacted with butyraldehyde to obtain poly(vinyl butyral).

[0003]

[0003] The above synthesis processes are energy intensive and depend on the use of non-renewable raw materials. Therefore, the prospect of recycled PVB resin derived from post-industrial and post-consumer PVB materials has long been considered in the art as a potentially valuable source of PVB that is less costly to produce than virgin PVB resin and can significantly reduce the environmental footprint of PVB production. Exemplary sources of post-industrial PVB materials include recycled PVB off-cuts and PVB rolls that are out of specification, damaged, or otherwise unusable. Exemplary sources of post-consumer PVB materials include post-used automobile windshields and architectural safety glass, as well as other post-used consumer products, such as power devices (e.g., photovoltaic devices) and electronic display devices.

[0004]

[0004] Despite the long-standing and urgent need in the art, there are several problems associated with recycled PVB. For example, both post-industrial and post-consumer PVB materials generally contain mixtures of different PVB compositions as obtained from various products and / or different manufacturers, as well as different 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 (PVOH) contents. Such compositional differences within the mixture of recycled PVB always result in unacceptably high haze and / or discoloration of the recovered 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 usefulness in recycling.

[0005]

[0005] Furthermore, when recycling PVB materials having different compositions, it can be difficult to produce a recovered PVB material having the specific composition required for a particular end use. For example, it may be necessary to recycle a PVB feed composition comprised of two different PVB-containing compositions to produce a recovered PVB material that can be used as a skin layer of an acoustical three-ply interlayer. Alternatively, it may be necessary to use the recovered PVB material as a core layer of an acoustical three-ply interlayer. However, in some interlayers, the residual PVOH content of the PVB material used in the skin layer is significantly different from the residual PVOH content of the PVB material used in the core layer. Summary of the Invention [Problem to be solved by the invention]

[0006]

[0006] Thus, a need exists to process post-industrial and / or post-consumer PVB in a manner that allows for precise control of the composition of the recycled PVB (e.g., residual PVOH content) so that recycled PVB is produced having the specific composition required for use in an interlayer of a new laminated glass panel (e.g., having a uniform residual PVOH content). [Means for solving the problem]

[0007] One aspect of the invention relates to a method for recovering poly(vinyl butyral) (PVB). The method includes mixing a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition. The PVB feed composition includes at least two different PVB-containing compositions. An additional step includes determining the residual polyvinyl alcohol (PVOH) content of the equilibrated PVB-containing composition. A further step includes adjusting the amount of butyraldehyde used in the mixing step based on the determined residual PVOH content.

[0008] Another aspect of the invention relates to a method for recovering poly(vinyl butyral) (PVB). The method includes a step of establishing a target residual polyvinyl alcohol (PVOH) content. An additional step includes combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition. The PVB feed composition includes at least two different PVB-containing compositions. An additional step includes measuring the residual PVOH content of the equilibrated PVB-containing composition. A further step includes adjusting the amount of butyraldehyde used in the combining step based on a comparison of the target residual PVOH content to the measured residual PVOH content.

[0009] Another aspect of the invention relates to a method for recovering poly(vinyl butyral) (PVB). The method includes the step of combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition. The PVB feed composition has a molecular weight greater than 200K Daltons. An additional step includes producing a PVB resin from the equilibrated PVB-containing composition, the PVB resin having a molecular weight at least 25K less than the molecular weight of the PVB feed composition.

[0010] Another aspect of the invention relates to a method for recovering poly(vinyl butyral) (PVB). The method includes the steps of combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde, and heating to produce an equilibrated PVB-containing composition. The PVB feed composition has a molecular weight greater than 200K Daltons. An additional step includes precipitating the PVB-containing composition to produce a PVB resin, the PVB resin having a molecular weight at least 25K less than the molecular weight of the PVB feed composition. [Brief description of the drawings]

[0011] [Figure 1A] FIG. 1 is a flow chart of a method for recovering PVB according to an embodiment of the present invention. [Figure 1B]

[0012] FIG. 2 is a flow chart of another method for recovering PVB according to an embodiment of the present invention. [Figure 2A]

[0013] FIG. 1 is a schematic diagram of a PVB recycling system according to an embodiment of the present invention. [Figure 2B]

[0014] 2 is a schematic diagram of another PVB recycling system according to an embodiment of the present invention. [Diagram 3]

[0015] 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 core layer and a pair of skin layers facing each other. [Figure 4]

[0016] 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. [Diagram 5]

[0017] FIG. 2 is a flow chart of another method for recovering PVB according to an embodiment of the present invention. [Figure 6]

[0018] FIG. 13 is a flow chart of yet another method for recovering PVB according to an embodiment of the present invention. [Figure 7]

[0019] FIG. 13 is a flow chart of yet another method for recovering PVB according to an embodiment of the present invention. [Figure 8]

[0020] FIG. 13 is a flow chart of yet another method for recovering PVB according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT EMBODIMENTS The present invention is directed to methods of recovering, recycling, and / or reusing poly(vinyl butyral) ("PVB"). More particularly, the present invention is directed to methods of recycling post-industrial and / or post-consumer PVB materials to obtain PVB polymer of sufficient quality that it can be used to form polymer interlayers and / or laminated glass panels that include polymer interlayers. In some embodiments, the PVB polymer recycled from post-industrial and / or post-consumer PVB materials can be used in other applications.

[0013]

[0022] More specifically, FIG. 1A illustrates an exemplary PVB recovery method 100 for recycling PVB according to an embodiment of the present invention. The method includes a step S110 of providing post-industrial and / or post-consumer PVB material to a regeneration system. An exemplary embodiment of the regeneration system 10 is illustrated diagrammatically in FIG. 2A, which may be in the form of a continuous regeneration system of interconnected vessels in which the various steps and methods discussed herein may be performed. However, it should be understood that the embodiments contemplate the use of various regeneration systems, such as a single batch reactor regeneration system. For example, the single batch reactor may include a vessel in the form of a continuous stirred tank reactor (CSTR) or another similar reactor, such as a countercurrent screw press extractor or other device known to those skilled in the art. One or more (or all) of the steps of the method 100 described herein may be performed in a single batch reactor. Alternatively, a continuous regeneration system may be used, as exemplified by the regeneration system 10, 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 compartments. Benefits of a continuous regenerative system can include higher throughput and higher efficiency compared to a single batch reactor.

[0014]

[0023] The PVB material added to the reclamation system 10 may be referred to herein as a "PVB feed composition" and may include post-industrial and / or post-consumer PVB material, as described above. However, in some embodiments, new or virgin PVB material may be used. Nevertheless, the PVB feed composition may be added to the mixing tank 12 of the reclamation system 10. The mixing tank 12 may be configured with various mechanisms necessary to combine, mix, and / or agitate the materials added to the tank 12. In some embodiments, the mixing tank 12 may also be configured to apply heat to the materials added to the mixing tank 12. In some embodiments, as step S120, a solvent may be added to the mixing tank 12 of the reclamation system 10 to dissolve the PVB feed composition and form a PVB solution. In some embodiments, the solvent may be added to the mixing tank 12 before the PVB feed composition is added to the mixing tank 12. In other embodiments, the solvent may be added to the mixing tank 12 after the PVB feed composition is added to the mixing tank 12.

[0015]

[0024] An additional step S130 may include adding a catalyst to the mixing tank 12 to form a PVB reaction mixture from the PVB solution (i.e., the PVB feed composition and the solvent). In various embodiments, the catalyst may be added to the mixing tank 12 before or after the addition of the PVB feed composition. An additional step S140 may optionally include adding butyraldehyde to the mixing tank 12 to aid in forming the PVB reaction mixture from the PVB solution. In various embodiments, butyraldehyde may be added to the mixing tank 12 before or after the addition of the PVB feed composition. During and / or before step S140, the PVB reaction mixture may be heated in the mixing tank 12 to facilitate mixing and / or to allow some initial equilibration of the different PVB-containing compositions within the PVB feed composition. The PVB reaction mixture may be transferred from the mixing tank 12 to a holding tank 14, where the PVB reaction mixture is heated in step S150 for a period of time to equilibrate the PVB reaction mixture to a homogenous PVB composition. As used herein, the term "balanced" is used to mean that the balanced composition has been processed to contain at least a generally uniform residual polyvinyl alcohol (PVOH) content.

[0016]

[0025] Once the PVB reaction mixture is equilibrated (so as to form a homogenous PVB composition), the equilibrated PVB reaction mixture may be transferred to a filtration tank 16 where the equilibrated PVB reaction mixture may be filtered to remove salts and other remaining solids in step S160. Such filtration may be performed by a mesh screen, a centrifugal filtration system, or other suitable method. In some embodiments, the PVB reaction mixture may be subjected to centrifugation prior to filtration. In some embodiments, step S160 may further include adding a base to the equilibrated PVB reaction mixture. In such embodiments, the base may be added before or after filtration of the equilibrated PVB reaction mixture. For example, a base may be added prior to filtration and / or centrifugation to neutralize a catalyst, which may then be extracted by filtration and / or centrifugation.

[0017]

[0026] The filtered equilibrated PVB reaction mixture may be transferred to a solvent column 18 where the remaining solvent may be extracted, such as by evaporation, in step S170. In certain embodiments, the solvent may be added from the solvent column 18 back to the mixing tank 12 for reuse in the PVB recovery process 100. Once the solvent has been removed from the equilibrated PVB reaction mixture, the remaining solids comprise a solid equilibrated PVB material which may be fed to an extruder 20 and used in an extrusion process to form various PVB products, such as the manufacture of polymer interlayers and / or laminated glass panels containing polymer interlayers, or may be used in a resin manufacturing process and reacetalized to form a PVB resin. The recovered PVB may also be used in other applications, such as adhesives that may be formed from the recovered PVB, as well as flooring, ceramic compositions, binders, coatings, inks, dispersions, and other applications.

[0018]

[0027] An alternative PVB recovery method 100' for recycling PVB according to an embodiment of the present invention is shown in FIG. 1B. Method 100' generally includes the same steps S110-S150 as discussed above with respect to method 100. Method 100' may be carried out using a regeneration system 10' as shown generally in FIG. 2B. However, in contrast to method 100, after the PVB reaction mixture is equilibrated in holding tank 14 in method 100' (to form a homogenous PVB composition), the equilibrated PVB reaction mixture may be transferred to a precipitation tank 22 illustrated in FIG. 2B instead of filtration tank 16. In precipitation tank 22, a solid equilibrated PVB material may be precipitated from the equilibrated PVB reaction mixture. In some embodiments, the PVB reaction mixture may be neutralized with a base before, during or after precipitation. In any case, the resulting solid equilibrated PVB material may be transferred from precipitation tank 22 to a washing tank 24 to wash and remove remaining salts and other impurities, as shown in step S170' in FIG. 1B. Additionally, solvent may be removed and recovered from wash vessel 24 and reintroduced into mixing vessel 12 (eg, via solvent column 18) as previously described.

[0019]

[0028] 2B, the solid, equilibrated PVB material may be transferred from the washing tank 24 to a drying tank 26 where residual water and other fluids may be removed. The resulting product is a recovered PVB polymer that may be fed to an extruder 20 for use in extrusion processes to form various PVB products, such as the manufacture of polymer interlayers and / or laminated glass panels containing polymer interlayers, or may be used in resin manufacturing processes and reacetalized to form PVB resin. The recovered PVB may also be used in other applications, such as adhesives that may be formed from the recovered PVB, as well as flooring, ceramic compositions, binders, coatings, inks, dispersions, and other applications.

[0020]

[0029] The following description provides further specificity to the above-described PVB recovery method 100 and / or 100'. In some embodiments, the PVB feed composition may include at least two different PVB-containing compositions. For example, the PVB feed composition may include a first PVB-containing composition and a second PVB-containing composition, where the first PVB-containing composition has a different PVB content (e.g., based on weight percent (wt.%)) than the second PVB-containing composition. Alternatively or in addition, the first PVB-containing composition may have a different PVOH content (e.g., based on weight percent (wt.%)) than the second PVB-containing composition. Alternatively or in addition, the first PVB-containing composition may have a different vinyl acetate content (e.g., based on weight percent (wt.%)) than the second PVB-containing composition. Alternatively or in addition, the first PVB-containing composition may have a different plasticizer content (e.g., based on parts per hundred parts of resin ("phr")) than the second PVB-containing composition. Alternatively or additionally, the first PVB-containing composition may have a different plasticizer type than the second PVB-containing composition. Alternatively or additionally, the first PVB-containing composition may have a different molecular weight than the second PVB-containing composition. Alternatively or additionally, the first PVB-containing composition may have a variety of additional (or fewer) additives than the second PVB-containing composition. Such additives may include, for example, adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants.

[0021]

[0030] Referring first to the PVOH content of the PVB feed composition, the PVB feed composition generally has a residual PVOH content of about 9 to about 25 wt.% or more, although other amounts are possible depending on the particular starting materials. For example, the various PVB-containing compositions of the PVB feed composition may each contain a residual PVOH content of about 0-8 wt.%, about 8-12 wt.%, about 12-16 wt.%, about 16-20 wt.%, about 20-26 wt.%, about 26-32 wt.%, about 32-40 wt.%, about 40-90 wt.%, or about 90-100 wt.%, respectively. Alternatively or in addition, the various PVB-containing compositions of the PVB-feed composition may each be at least 8, at least 9, at least 9.5, at least 10, at least 10.5, at least 11, at least 11.5, at least 12, at least 12.5, at least 13, at least 13.5, at least 14, at least 14.5, at least 15, at least 15.5, at least 16, at least 16.5, at least 17, at least 17.5, at least 18, at least 18.5, at least 19, at least 19.5, at least 20, at least 25, at least 26, at least 30, at least 32, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 70, at least 80, at least 90, at least 100, at least 105 ... , at least 50, at least 60, at least 70, at least 80, or at least 90 wt.%, and / or a residual PVOH content of 100 wt.%, 90 wt.%, 80 wt.%, 70 wt.%, 60 wt.%, 50 wt.%, 40 wt.%, 35 wt.%, 32 wt.%, 30 wt.%, 25 wt.%, 22 wt.%, 20 wt.%, 19 wt.%, 18 wt.%, 17 wt.%, 16 wt.%, 15 wt.%, 14 wt.%, 13 wt.%, 12 wt.%, 11 wt.%, 10 wt.%, 9 wt.%, or 8 wt.%.

[0022]

[0031] As discussed above, a PVB-feed composition may include multiple different PVB-containing compositions, each having a different PVOH content. For example, a first PVB-containing composition of the PVB-feed composition may have a residual PVOH content of about 9-15 wt.%, while a second PVB-containing composition of the PVB-feed composition may have a residual PVOH content of about 15-25 wt.%. Nevertheless, such exemplary PVOH amounts are provided for illustrative purposes only, and other ranges of residual PVOH contents (or different PVOH ranges) may be possible depending on the materials used and the source of the materials. For example, multiple different PVB-containing compositions of a given PVB-feed composition may each have any of the residual PVOH contents (or PVOH ranges) listed above in the previous paragraph. Further, in some specific embodiments, the first and second PVB-containing compositions from the PVB-feed composition may have a relative difference in residual PVOH content of at least 0.5 wt.%, at least 1 wt.%, at least 2 wt.%, at least 4 wt.%, at least 6 wt.%, at least 8 wt.%, at least 10 wt.%, at least 12 wt.%, at least 14 wt.%, or at least 16 wt.%, and / or from 0.5 to 16 wt.%, from 0.5 to 14 wt.%, from 1 to 12 wt.%, from 2 to 10 wt.%, or from 4 to 8 wt.%.

[0023]

[0032] The PVB feed composition may also contain various amounts and types of plasticizers, which are generally used to soften the PVB and / or increase the glass transition temperature (T g) are used to lower the viscosity of the plasticizer. Types of plasticizers contemplated include, but are not limited to, esters of polybasic acids, polyhydric alcohols, triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexonate) (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, nonylphenyltetraethylene glycol, and mixtures thereof.

[0024]

[0033] Other suitable plasticizers may include blends of two or more separate plasticizers, including, but not limited to, those listed above. Still other suitable plasticizers or blends of plasticizers may be formed from aromatic groups, such as polyadipates, epoxides, phthalates, terephthalates, benzoates, toluates, mellitates, and other specialty plasticizers. Further examples include, but are not limited to, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol benzoate isobutyrate, 1,3-butanediol dibenzoate, diethylene glycol di-o-toluate, triethylene glycol di-o-toluate, dipropylene glycol di-o-toluate, 1,2-octyl dibenzoate, tri-2-ethylhexyl trimellitate, di-2-ethylhexyl terephthalate, bis-phenol A bis(2-ethylhexanoate), ethoxylated nonylphenol, and mixtures thereof. In some embodiments, the plasticizer may be selected from the group consisting of dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, and combinations thereof.

[0025]

[0034] As mentioned above, the plasticizer content of the PVB feed composition (e.g., resin or recycled PVB) is measured in phr, on a weight per weight basis. For example, if 30 grams of plasticizer are added to 100 grams of polymer resin, the plasticizer content of the resulting plasticized polymer is 30 phr. The PVB feed composition may have various amounts and / or types of plasticizer. For example, the various PVB-containing compositions of the PVB feed composition may each contain a plasticizer content of about 0-10 phr, about 10-20 phr, about 20-30 phr, about 30-40 phr, about 40-50 phr, about 50-60 phr, about 60-70 phr, about 70-80 phr, about 80-90 phr, or about 90-100 phr. Alternatively or in addition, the various PVB-containing compositions of the PVB-feed composition may comprise one or more plasticizers at a plasticizer content of at least about 20 phr, at least about 25 phr, at least about 30 phr, at least about 35 phr, at least about 38 phr, at least about 40 phr, at least about 45 phr, at least about 50 phr, at least about 55 phr, at least about 60 phr, at least about 65 phr, at least about 67 phr, at least about 70 phr, at least about 75 phr, respectively. In some embodiments, the various PVB-containing compositions of the PVB-feed composition may also each include about 100 phr or less, about 85 phr or less, 80 phr or less, about 75 phr or less, about 70 phr or less, about 65 phr or less, about 60 phr or less, about 55 phr or less, about 50 phr or less, about 45 phr or less, about 40 phr or less, about 38 phr or less, about 35 phr or less, or about 30 phr or less of one or more plasticizers.

[0026]

[0035] Additionally, the PVB feed composition may have various PVB contents, which may be defined as butyral or acetal contents. The various PVB-containing compositions of the PVB feed composition may each have a PVB content of at least about 50 wt.%, at least about 55 wt.%, at least about 60 wt.%, at least about 65 wt.%, at least about 70 wt.%, at least about 75 wt.%, at least 80 wt.%, at least 85 wt.%, at least 90 wt.%, at least 95 wt.%, or up to 100 wt.%, and / or between 50 and 100 wt.%, respectively. .%, 50-90wt.%, 50-80wt.%, 50-70wt.%, 50-60wt.%, 60-100wt.%, 60-90wt.%, 60-80wt.%, 60-70wt.%, 70-100wt.%, 70-90wt.%, 70-80wt.%, 80-100wt.%, 80-90wt.%, or 90-100wt.% PVB content and / or butyral / acetal content.

[0027]

[0036] The PVB-feed composition may have various vinyl acetate contents. The various PVB-containing compositions of the PVB-feed composition may each contain a vinyl acetate content of up to about 15 wt.%, up to about 10 wt.%, or up to about 5 wt.%, and / or from 5-15 wt.%, 5-10 wt.%, or 10-15 wt.%, respectively.

[0028]

[0037] Additionally, the PVB-feed composition may have a variety of molecular weights. The various PVB-containing compositions of the PVB-feed composition may each comprise a molecular weight of about 50,000 to about 600,000, about 70,000 to about 450,000, about 100,000 to about 425,000, about 150,000 to about 350,000, and / or about 200,000 to about 300,000 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. Alternatively or additionally, in certain specific embodiments, the various PVB-containing compositions of the PVB-feeding composition may each comprise a molecular weight of about 100,000 to about 175,000 daltons, about 120,000 to about 150,000 daltons, about 200,000 to about 250,000, about 250,000 to about 350,000 daltons, and / or about 275,000 to about 325,000 daltons.

[0029]

[0038] Additionally, the PVB feed composition may have a variety of other additives or impurities. The various PVB-containing compositions of the PVB feed composition each contain different amounts of adhesion control agents (ACAs), UV stabilizers, antioxidants, IR absorbers or blockers (e.g., indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaB), among other additives known to those skilled in the art. 6 ) and cesium tungsten oxide), colorants (e.g., dyes and pigments), antiblocking agents, flame retardants, processing aids, flow improving additives, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcing additives, and fillers.

[0030]

[0039] As shown in step S110 in PVB recovery method 100 and / or 100', prior to adding the PVB feed composition to reclamation system 10 and / or 10', the material of the PVB feed composition may be cut, chopped, and / or shredded to form small diameter (e.g., 2-20 mm, but 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. As discussed above, the PVB feed composition may include multiple different PVB-containing compositions. Thus, flakes, chips, and / or pellets of PVB material may be combined together to form a mixed composition (e.g., having mixed amounts of PVOH or other elements). Such PVB feed composition may then be fed to reclamation system 10 and / or 10', which may be in the form of a single batch reactor recycle system or a continuous regeneration recycle system, as discussed above.

[0031]

[0040] Referring again to step S120 of the PVB recovery method 100 and / or 100', the solvent added to the regeneration system 10 and / or 10' may include a variety of solvents sufficient to selectively dissolve the components of the PVB feed composition 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. The solvent is configured to dissolve the PVB feed composition to form a PVB solution having the form of a cloudy viscous solution. In some embodiments, a certain amount of water may be added to the solvent and / or PVB feed composition to aid in dissolving the PVB feed composition. Other alcohols, such as alcohols with more than three carbon atoms, such as n-butanol, or alcohols with more than one hydroxyl group (i.e., diols and triols), may also be used.

[0032]

[0041] Referring to step S130, the catalyst may include various catalysts such as sulfuric acid, sulfonic acid, sulfonating acid, methanesulfonic acid, or p-tolylsulfonic acid (p-toluenesulfonic acid). Referring to step S140, butyraldehyde may also be optionally used to aid in the formation of the PVB reaction mixture and to make the equilibrated PVB. As described in more detail below, the inventors have found that the amount of butyraldehyde used in the PVB recovery process 100 and / or 100' can affect the residual PVOH content of the resulting equilibrated PVB. Thus, embodiments of the present invention include the feature of adjusting the amount of butyraldehyde used in the PVB recovery process 100 and / or 100' to precisely control the amount of residual PVOH in the resulting equilibrated PVB.

[0033]

[0042] Once the materials described above have been added to the mixing tank 12 (i.e., the PVB feed composition, the solvent, the catalyst, and optionally the butyraldehyde), the mixing tank 12 can combine, mix, and / or agitate the materials to form a PVB reaction mixture. In some embodiments, the mixing tank 12 can also be configured to apply heat to the materials added to the mixing tank 12. Upon addition of the catalyst and butyraldehyde, the PVB reaction mixture can be about 15-25 wt.% PVB material (or 17 wt.%-23 wt.%, or 18 wt.%-22 wt.%, or about 20 wt.% PVB material), about 75-85 wt.% solvent (or 77 wt.%-83 wt.%, or 78 wt.%-82 wt.%, or about 80 wt.% solvent), about 10 wt.% PVB material, about 15 wt.% PVB material, about 17 wt.% PVB material, about 18 wt.% PVB material, about 20 wt.% PVB material, about 25 ... % butyraldehyde (or 0.25 wt.% to 2.0 wt.%, or 0.5 wt.% to 1.5 wt.%, or 0.75 wt.% to 1.25 wt.% butyraldehyde), about 0.3 wt.% water (or 0.1 wt.% to 0.5 wt.%, or 0.2 wt.% to 0.4 wt.% water), and / or about 0.05 wt.% catalyst. However, as discussed above and in more detail below, the amount of butyraldehyde used in PVB recovery process 100 and / or 100' may be adjusted as necessary to achieve a target residual PVOH content in the resulting equilibrated PVB.

[0034]

[0043] In step S150, the PVB reaction mixture may be transferred to a holding tank 14 to facilitate equilibration of the individual PVB-containing compositions in the PVB feed composition (now in the form of a PVB reaction mixture). More specifically, the PVB reaction mixture may be heated for a period of time. The mixture may be heated to a temperature of 65° C. to 85° C., 70° C. to 80° C., 70° C. to 78° C., or about 78° C. The period of heating may be at least 1 hour, at least 2 hours, at least 3 hours, and / or 1 to 5 hours, 2 to 4 hours, or about 3 hours. The heating, catalyst, and butyraldehyde enable the PVB reaction mixture to equilibrate the various PVB-containing compositions of the PVB feed composition into a uniform composition. For example, the PVB reaction mixture may equilibrate such that the PVB portion of the mixture reaches a uniform residual PVOH content.

[0035]

[0044] Referring to step S160 of the PVB recovery method 100, the equilibrated PVB reaction mixture may be transferred to a filtration vessel 16 where the mixture may be cooled and filtered to remove salts and other impurities. In some embodiments, the PVB reaction mixture may be cooled to a temperature below the temperature to which the mixture was heated in step S150. In some embodiments, a base is added to the equilibrated PVB reaction mixture to neutralize the mixture prior to filtration. In some embodiments, the base may include potassium hydroxide ("KOH"), sodium hydroxide, and the like. In some embodiments, the amount of base added to the mixture may comprise about 0.05 wt.% of the mixture. In some specific embodiments, the amount of base may be at least 0.02 wt.%, at least 0.03 wt.%, at least 0.04 wt.%, at least 0.05 wt.%, at least 0.06 wt.%, at least 0.07 wt.%, or at least 0.08 wt.% of the equilibrated PVB reaction mixture. In other embodiments, the base may form 0.02 wt.% to 0.08 wt.%, 0.03 wt.% to 0.07 wt.%, 0.04 wt.% to 0.06 wt.%, or about 0.05 wt.% of the equilibrated PVB reaction mixture. In any event, embodiments may provide that a sufficient amount of base is added so that the pH of the equilibrated PVB reaction mixture (which is about 2.0-2.5 before neutralization) reaches about 5.0 to about 7.0, or at least about 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.7, 6.8, 6.9 or 7.0, or about 5.1 to about 6.9, or about 5.2 to about 6.8, or about 5.3 to about 6.7, or about 5.4 to about 6.7, or about 5.5 to about 6.7, or about 5.6 to about 6.7, or about 5.7 to about 6.7, or about 5.8 to about 6.7, or about 5.9 to about 6.7.

[0036]

[0045] Step S160 may further include centrifuging and filtering the equilibrated PVB reaction mixture (e.g., neutralized as described above) to remove salts and other solids from the mixture. In some embodiments, the filter may include a screen, mesh, cloth, or other similar filtering element. The filtered equilibrated PVB reaction mixture may be fed to a solvent column 18 in step S170 where the solvent may be extracted (e.g., via evaporative distillation, steam stripping, extrusion evaporation, etc.). In certain embodiments, the solvent may be reused in the PVB recovery process 100 by adding it back to the mixing tank 12 from the solvent column 18. Once the solvent and catalyst are removed, the remaining solids include solid equilibrated PVB, which may be fed to the extruder 20 (e.g., for use in forming a polymer interlayer).

[0037]

[0046] Alternatively, as shown in PVB recovery method 100', after the PVB reaction mixture is equilibrated in holding tank 14 (to form a homogenous PVB composition), the equilibrated PVB reaction mixture may be transferred to precipitation tank 22 where solid PVB is precipitated from the equilibrated PVB reaction mixture as shown in step S160'. In some embodiments, the equilibrated PVB reaction mixture may be neutralized with a base before, during, or after precipitation. The resulting solid equilibrated PVB may be transferred from precipitation tank 22 to washing tank 24 to remove salts and other impurities as shown in step S170'. Additionally, as previously described, solvent may be recovered from washing tank 24 and reintroduced into mixing tank 12 (e.g., via solvent column 18). Specifically, solvent may be removed from washing tank 24 to solvent column 18 (e.g., via evaporative distillation, steam stripping, extrusion evaporation, etc.).

[0038]

[0047] The solid, equilibrated PVB may be transferred from the washing tank 24 to a drying tank 26 where residual water and other fluids may be removed. The resulting product is a recovered PVB polymer (equilibrated to have a uniform residual PVOH content) which may be fed to an extruder 20 for use in extrusion processes to form various PVB products, such as the manufacture of polymer interlayers and / or laminated glass panels containing polymer interlayers, or may be used in resin manufacturing processes and reacetalized to form PVB resin. The recovered PVB may 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.

[0039]

[0048] In certain embodiments, steps S110-S170 of method 100 described above (or steps S110-S170' of method 100') may be modified, added, and / or removed. Additionally, the recovered PVB polymer may be subjected to further processing as required for a particular end use application.

[0040]

[0049] The PVB recovered using the above PVB recovery method 100 and / or 100' can be used to form a resin, a resin layer, a polymer interlayer, and / or a laminated glass panel including a polymer interlayer. 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 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.

[0041]

[0050] Although the above steps of the PVB recovery method 100 can be performed to obtain a recovered PVB having at least some inherent plasticizer (e.g., 3-5 phr plasticizer, 10-20 phr plasticizer, 35-45 phr plasticizer, or various other amounts 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, additional amounts of less than 25 phr, or less than 20 phr, or less than 25 phr, 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. The recovered PVB resin (or resins) typically have a molecular weight of greater than 30,000 daltons, or less than 500,000 daltons, or from about 30,000 to about 500,000 daltons, or from about 100,000 to about 400,000 daltons, or from 100,000 to about 175,000 daltons, or from about 200,000 to about 250,000 daltons, or from about 250,000 to about 350,000 daltons.

[0042]

[0051] Once a sufficient amount of plasticizer has been added to the recycled PVB, it is believed that the polymer interlayer sheet can be produced by any suitable process known to those skilled in the art of producing polymer interlayer sheets that can be used in multi-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. While 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, this application will focus on polymer interlayer sheets produced by extrusion and / or coextrusion processes.

[0043]

[0052] 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.

[0044]

[0053] 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 has an opening, generally defined by a lip, that has one dimension substantially larger than the perpendicular dimension. Generally, the die is 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.

[0045]

[0054] 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 a fixed volume throughput of different thermoplastic melts of different viscosities or other properties and pump them through a coextrusion die into the desired final form. For example, the multilayer interlayer of the present invention (e.g., in the form of a three-layer interlayer) may preferably be 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.

[0046]

[0055] 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 built 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.

[0047]

[0056] 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 excess interlayer is trimmed off from the edges to create an assembly. It is not uncommon 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.

[0048]

[0057] In view of the above, a multi-layer panel includes two sheets of glass, or other applicable substrate, with a polymer interlayer sheet(s) sandwiched therebetween. Multi-layer panels are generally produced by placing at least one polymer interlayer sheet between two substrates to create an assembly. FIG. 3 shows a multi-layer panel 50 including a pair of glass sheets 52 with a multi-layer interlayer sandwiched therebetween. The multi-layer interlayer is configured as an acoustical three-ply interlayer having three individual polymer interlayer sheets, including a soft core layer 54 and two relatively hard skin layers 56 disposed on either side of the core layer 54. Such glass panels incorporating such a three-ply may have better acoustic properties due to the sound reduction provided by the soft core layer, as discussed above.

[0049]

[0058] In some embodiments, the intermediate layer (e.g., the core layer 54 and the skin layer 56) have a generally constant or uniform thickness over the length of the intermediate layer (see, e.g., FIG. 3). However, in alternative embodiments, the intermediate layer may have at least one region of non-uniform thickness, as shown in the multi-layer panel 60 of FIG. 4. For example, the intermediate layer, including the core layer 54 and the skin layer 56, 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 54 (i.e., the skin layer 56 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 56 (i.e., the core layer 54 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 54 and the skin layer 56. 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).

[0050]

[0059] Beneficially, laminated glass panels formed with at least one polymer layer / interlayer containing the recovered PVB obtained from the PVB recovery method 100 and / or 100' discussed above may have excellent optical quality. Such quality is generally due to the recovered PVB being equilibrated to have a uniform residual PVOH content. For example, when the recovered PVB (i.e., the equilibrated PVB-containing composition) is mixed with 20 phr of plasticizer to form a PVB resin, the PVB resin is formed into a PVB layer of 0.772 mm, and placed between two sheets of 2.3 mm glass to form a laminated glass panel, the laminated glass panel may have a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%. 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 according to ASTM D1003-Procedure B using Illuminant C at an observation angle of 2 degrees.

[0051]

[0060] However, it may be difficult to produce a polymer layer / interlayer with the required residual PVOH content to be formed into a particular layer of a polymer interlayer. For example, as described above, in the case of an acoustical three-ply interlayer, the soft core layer is generally characterized by a lower residual PVOH content, while the relatively harder skin layers are generally characterized by a higher residual PVOH content. Considering that the PVB feed composition used in the PVB recovery method 100 and / or 100' may contain multiple different PVB-containing compositions, the recovered PVB (after being recycled by the above-described PVB recovery method 100 and / or 100') may be formed with various levels of residual PVOH content, which may make it unsuitable for use as a skin or core layer of a three-ply interlayer. However, the inventors have discovered that by controlling the amount of butyraldehyde used in the PVB recovery method 100 and / or 100', the residual PVOH content of the recovered PVB can be precisely controlled. For example, by increasing the amount of butyraldehyde used in the PVB recovery process 100 and / or 100', the residual PVOH content of the recovered PVB can be reduced, while by decreasing the amount of butyraldehyde used in the PVB recovery process 100 and / or 100', the residual PVOH content of the recovered PVB can be increased.

[0052]

[0061] In view of the above, as shown in Figure 5, embodiments of the present invention include a further PVB recovery method 200 for controlling the amount of residual PVOH content of the recovered PVB. The method 200 includes an initial step S210 of mixing a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition. In some embodiments, the PVB feed composition includes at least two different PVB-containing compositions. An additional step S220 includes determining the residual PVOH content of the equilibrated PVB-containing composition. A further step S230 includes adjusting the amount of butyraldehyde used in the mixing step S210 based on the determined residual PVOH content.

[0053]

[0062] More specifically, the PVB feed composition may be mixed with a solvent, catalyst, and optionally butyraldehyde in the mixing vessel 12 and / or holding vessel 14 of the regeneration system 10 as described above with respect to the PVB recovery methods 100 and / or 100' to produce an equilibrated PVB-containing composition, as shown in step S210. As further described above, the PVB feed composition may include at least two different PVB-containing compositions, e.g., a first PVB-containing composition having a different residual PVOH content than a second PVB-containing composition. Nonetheless, once the PVB feed composition is equilibrated, the residual PVOH content of the equilibrated PVB-containing composition may be uniform and may be determined as shown in step S220.

[0054]

[0063] In some embodiments, the residual PVOH content may be determined when the equilibrated PVB-containing composition is in solution form, such as when the equilibrated PVB-containing composition is in holding tank 14, filtration tank 16, and / or precipitation tank 22. In some embodiments, the residual PVOH content of the equilibrated PVB-containing composition in solution form may be tested by cloud point measurements. Such cloud point measurements may be performed on a sample of the equilibrated PVB-containing composition solution extracted from holding tank 14, filtration tank 16, and / or precipitation tank 22. Alternatively, cloud point measurements may be performed directly on the equilibrated PVB-containing composition solution in holding tank 14, filtration tank 16, and / or precipitation tank 22.

[0055]

[0064] In other embodiments, the residual PVOH content may be determined when the equilibrated PVB-containing composition is in solid or resinous form, e.g., when solid PVB is obtained from the equilibrated PVB reaction mixture in solvent column 18, in precipitation tank 22 (e.g., after precipitation), in washing tank 24 (e.g., after evaporation), drying tank 26, and / or after the recovered PVB is otherwise formed into a resin for introduction into extruder 20. In some embodiments, the residual PVOH content of the equilibrated PVB-containing composition in solid or resinous form may be tested by infrared sensor and / or titration. Such tests may be performed on samples of the equilibrated PVB-containing composition (in solid or resinous form) extracted from solvent column 18, from precipitation tank 22, from washing tank 24, from drying tank 26, and / or otherwise prior to introduction into extruder 20. Alternatively, testing may be performed directly on the equilibrated PVB-containing composition (in solid or resin form) in the solvent column 18, in the precipitation tank 22, in the washing tank 24, in the drying tank 26, and / or in the feed line that supplies the PVB resin to the extruder 20.

[0056]

[0065] Based on the measured residual PVOH content of the equilibrated PVB, embodiments provide that the residual PVOH content is adjusted. As discussed above, the inventors have found that by increasing the amount of butyraldehyde used in the PVB recovery process 100 and / or 100', the residual PVOH content of the recovered PVB can be reduced, while by decreasing the amount of butyraldehyde used in the PVB recovery process 100 and / or 100', the residual PVOH content of the recovered PVB can be increased. Thus, a target residual PVOH content of the equilibrated PVB can be established, and the amount of butyraldehyde used in the PVB recovery process 100 and / or 100' can be adjusted to achieve such target.

[0057]

[0066] In some embodiments, the target residual PVOH content of the balanced PVB may be set at 14-50 wt.%, 15-25 wt.%, 16-22 wt.%, or 18.0-20.0 wt.%. Such targets may be used, for example, in embodiments where the balanced PVB is formed into a resin for use in a skin layer of an acoustical tri-ply. In other embodiments, the target residual PVOH content of the balanced PVB may be set at 5-15 wt.%, 7-13 wt.%, or 9-11 wt.%. Such targets may be used, for example, in embodiments where the balanced PVB is formed into a resin for use in a core layer of an acoustical tri-ply.

[0058]

[0067] The amount of butyraldehyde used in PVB recovery process 100 can be adjusted by varying the amount of butyraldehyde used in mixing tank 12. For example, in situations where the residual PVOH content of, for example, the equilibrated PVB recovered from PVB recovery process 100 is greater than a target, the amount of butyraldehyde used in mixing tank 12 may be increased (i.e., butyraldehyde is added to mixing tank 12 from solvent column 18 or from a fresh butyraldehyde feedstock). In contrast, in situations where the residual PVOH content of, for example, the equilibrated PVB recovered from PVB recovery process 100 and / or 100' is less than a target, the amount of butyraldehyde used in mixing tank 12 may be decreased (i.e., butyraldehyde may be extracted from mixing tank 12).

[0059]

[0068] In some embodiments, one or more of (i) determining the residual PVOH content of the equilibrated PVB, (ii) comparing it to a target residual PVOH content, and (iii) adjusting the amount of butyraldehyde used in the PVB recovery process may be automated. For example, an embodiment may include a control system (e.g., including memory elements, processing elements, and / or input / output elements) for automatically (i) determining the residual PVOH content of the equilibrated PVB in the PVB recovery process, (ii) comparing the determined residual PVOH content to a target residual PVOH content, and (iii) automatically adjusting the amount of butyraldehyde used in the PVB recovery process. Thus, the control system may be part of the regeneration system 10 and / or 10' and may be in communication with a test device (e.g., a sensor) that performs a test (e.g., cloud point, infrared, titration test) of the residual PVOH content of the equilibrated PVB in the system 10 and / or 10'. Upon receiving data indicative of the residual PVOH content of the equilibrated PVB, the control system may compare such data to a target residual PVOH content established and stored in the control system. Based on such a comparison, the control system may automatically adjust the amount of butyraldehyde used in the PVB recovery process (e.g., the amount used in mixing vessel 12 of systems 10 and / or 10'). The control system may perform such steps based on a processing element executing computer-implemented instructions stored on a storage element (e.g., a non-transitory computer-readable storage medium) of the control system.

[0060]

[0069] In view of the above, embodiments provide another method 300 of recovering PVB, shown in FIG. 6. Method 300 includes a step 310 of determining a target residual PVOH content. An additional step 320 includes combining the PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition. The PVB feed composition may include at least two different PVB-containing compositions. An additional step 330 includes measuring the residual PVOH content of the equilibrated PVB-containing composition. A further step 340 includes adjusting the amount of butyraldehyde used in the combining step 310 based on a comparison of the target residual PVOH content to the measured residual PVOH content.

[0061]

[0070] As a further advantage, the recovered PVB resulting from the PVB recovery method 100 and / or 100' discussed above may be formed with a preferred molecular weight for use in an acoustical three-ply interlayer. More specifically, the inventors have found that the recovered PVB resulting from the PVB recovery method 100 and / or 100' may have a reduced molecular weight relative to the PVB feed composition fed to the method. In some examples, the PVB feed composition may include recycled PVB formed from an acoustical three-ply interlayer. Such an acoustical three-ply interlayer may include a combination of skin and core layers, with the core layer generally having a higher molecular weight than the skin layer. If the recovered PVB is to be used in the skin layers of a new acoustical three-ply interlayer, the molecular weight of the recovered PVB should generally be less than the PVB feed composition. Advantageously, the PVB recovery method 100 and / or 100' provides that the recovered PVB has a reduced molecular weight relative to the PVB feed composition, as the steps of the PVB recovery method 100 unbind, dissolve, and / or cleave the interchain linkages of the PVB feed composition. An additional advantage of the recovered PVB having a reduced molecular weight (relative to the PVB feed composition) is that the recovered PVB also has a lower viscosity (relative to the PVB feed composition), which improves the flow of the PVB resin through an extruder and / or autoclave.

[0062]

[0071] In view of the above, an embodiment of the present invention provides another method 400 for recovering PVB, as shown in Figure 7. The method 400 includes an initial step S410 of mixing a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition, the PVB feed composition having a molecular weight greater than 200,000 (200K) Daltons. In other embodiments, the PVB feed composition may have a molecular weight greater than 225K, greater than 250K, greater than 275K, and / or greater than 300K Daltons. Additionally, the PVB feed composition may have a viscosity greater than 230 cps. An additional step S420 may include producing a PVB resin from the equilibrated PVB-containing composition, the PVB resin having a molecular weight at least 25K less than the molecular weight of the PVB feed composition. In other embodiments, the PVB resin may have a molecular weight that is at least 30K, at least 40K, at least 50K, at least 60K, at least 70K, at least 80K, at least 90K, or at least 100K Daltons less than the molecular weight of the PVB feed composition. Further, the PVB resin may have a viscosity that is at least 10 cps, at least 15 cps, and / or at least 20 cps less than the viscosity of the PVB feed composition. Alternatively or additionally, the PVB resin may have a viscosity that is at least 10%, at least 15%, at least 20%, or between 10-20% less than the viscosity of the PVB feed composition. For example, the PVB resin may have a viscosity of less than 230 cps, less than 220 cps, less than 210 cps, and / or less than 200 cps.

[0063]

[0072] Finally, an embodiment of the invention may provide another method 500 for recovering PVB, shown in Figure 8. Method 500 includes an initial step S510 of combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde and heating to produce an equilibrated PVB-containing composition, the PVB feed composition having a molecular weight greater than 200K Daltons. An additional step S520 may include precipitating the equilibrated PVB-containing composition to produce a PVB resin, the PVB resin having a molecular weight at least 25K less than the molecular weight of the PVB feed composition. EXAMPLES

[0064] Example 1

[0073] A mixture of 850 parts of SD29 alcohol (190 proof ethanol), 150 parts of PVB resin with a PVOH content of 10.50 wt.% (referred to herein as "starting PVB resin"), 3 parts of water, and 0.4 parts of sulfuric acid was charged into a 1-liter three-neck jacketed glass reactor. The mixture was stirred and heated to 78°C and held there for 4 hours. The resulting mixture was cooled to 65°C and neutralized with 0.46 parts of KOH until the mixture reached a pH of 6. The resulting cloudy mixture was further mixed with 8 equivalents of water in a high intensity mixer to form a PVB slurry. The alcohol and residual butyraldehyde were removed from the PVB slurry by fill and drain washes with deionized water, and the resulting slurry was filtered and dried. After drying, 134 parts of "recovered PVB resin" was obtained. The recovered PVB resin had a PVOH content of 18.38 wt.% as measured using a Bomem MB160 FT- (near infrared) NIR Analyzer. It should be noted that the Bomem MB160 FT-NIR Analyzer was calibrated using PVB resin samples with known residual PVOH content determined using titration.

[0065]

[0074] Further, each of the starting PVB resin and the recovered PVB resin was subjected to viscosity measurement by the following "Viscosity Test". First, 50 ml of 92 wt.% isopropanol in deionized water at 20° C. was dispensed into a 118 ml (4 oz) test bottle. 1.9084 gm of the resin sample was added to the test bottle and vigorously shaken for 30 minutes. The test bottle was placed in a 45° C. bath for at least 60 minutes. The test bottle was removed from the bath and shaken again until complete dissolution was achieved. The test bottle was then placed in a 20° C. bath for 60 minutes. The viscometer tube was placed in the 20° C. bath and allowed to equilibrate for approximately 5 minutes. Using a fast flow pipette, 10 ml of the solution was transferred from the test bottle to a viscometer tube (e.g., Cannon Fenske Viscometer No. 400). A pressure valve was used to force the fluid to the top mark of the viscometer. The pressure was released to allow the liquid level to flow past the top mark of the viscometer. A timer was used to calculate the time for the liquid in the viscometer to pass between the upper and lower marks. The viscosity in centistokes was determined by multiplying the measured time by the tube coefficient associated with the viscometer. The viscosity in centipoise was determined by multiplying the viscosity in centistokes by the solution density in gm / cc. Using the viscosity test, the viscosity of the starting PVB resin was determined to be 234 cps, while the viscosity of the recovered PVB resin was found to be reduced to 213 cps.

[0066]

[0075] Additionally, the molecular weights of the starting and recovered PVB resins were measured using the "Molecular Weight Test" described below. It was found that the starting PVB resin had a molecular weight of 273,031 Daltons, while the viscosity of the recovered PVB resin was reduced to a molecular weight of 245,203 Daltons. More specifically, the molecular weight test included gel permeation chromatography ("GPC") using Hexafluoroisopropanol AR from Biosolve as the GPC mobile phase (0.8 ml / min). Each sample was prepared by weighing approximately 20 mg of PVB resin into a 25 ml flask and adding 10 ml of mobile phase. The flask was then placed in an automatic shaking device until the PVB resin was completely dissolved. The analysis was performed on a three-detector system consisting of a Viscotek GPCmax (autosampler, pump and degasser), a Viscotek triple detector TDA302 (combined RALL / LALLS, viscometer and DRI), and a column oven. The separation was carried out on three Viscotek mixed bed columns type I-MB (low, medium and high molecular weight range) maintained at 45° C. The detector set-up was calibrated using a narrow PMMA standard from Viscotek with a reported molecular weight of 64,368 Daltons, inherent viscosity of 0.615 and dn / dc value of 0.189. The refractive index of the mobile phase was determined by preliminary experiments to be 1,2649 g / ml.

[0067] Example 2

[0076] A mixture of 800 parts SD29 alcohol (190 proof ethanol), 200 parts recycled PVB resin formed from an acoustical 3-ply interlayer (having skin layers with 10.50 wt.% PVOH content and a core layer with 18.70 wt.% PVOH content), 3 parts water, and 0.5 parts sulfuric acid was charged into a 1 liter, three-neck jacketed glass reactor. The mixture was stirred and heated to 78°C and held there for 4 hours. The resulting mixture was cooled to 65°C and neutralized with 0.46 parts KOH until the mixture reached a pH of 6. The resulting cloudy mixture was filtered to obtain a clear viscous solution. The solution was cast into a film and dried to obtain a clear film. The film was pressed into a 0.772 mm thick film of recovered PVB resin. The recovered PVB resin was found to have a PVOH content of 23.08 wt.% using the Bomem MB160 FT-NIR Analyzer previously described.

[0068] Example 3

[0077] A mixture of 800 parts SD29 alcohol, 200 parts recycled PVB formed from an acoustical 3-ply interlayer (having skin layers with 10.50 wt.% PVOH content and a core layer with 18.70 wt.% PVOH content), 15 parts butyraldehyde, 3 parts water, and 0.5 parts sulfuric acid was charged into a 1-liter, three-necked jacketed glass reactor. The mixture was stirred and heated to 78° C. and held there for 4 hours. The resulting mixture was cooled to 65° C. and neutralized with 0.46 parts KOH until the mixture reached a pH of 6. The resulting cloudy mixture was filtered to obtain a clear viscous solution. The solution was cast into a film and dried to obtain a clear film. The film was pressed into a 0.772 mm thick film of recovered PVB resin. The recovered PVB resin was found to have a PVOH content of 18.77 wt.% using the Bomem MB160 FT-NIR Analyzer described above.

[0069]

[0078] Although the present invention is disclosed in conjunction with a 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.

[0070]

[0079] It will be further understood that any of the ranges, values, or properties set forth for any single component of this disclosure can be used interchangeably with any of the ranges, values, or properties set forth for any of the other components of this 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 this invention but would be burdensome to list.

[0071]

[0080] The present invention and its preferred embodiments will now be further described with reference to numbered items 1-114.

[0072]

[0081] Item 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to form an equilibrated PVB-containing composition, the PVB feed composition comprising at least two different PVB-containing compositions; (b) determining the residual polyvinyl alcohol (PVOH) content of the equilibrated PVB-containing composition;

[0082] adjusting the amount of butyraldehyde used in said mixing in step (a) based on the residual PVOH content determined in step (b); A method comprising:

[0073]

[0083] Item 2. The method of item 1, further comprising the step of setting a target residual PVOH content of the equilibrated PVB-containing composition.

[0074]

[0084] Item 3. The method of item 2, wherein if the residual PVOH content determined in step (b) is greater than the target residual PVOH content, said adjusting in step (c) comprises increasing the amount of butyraldehyde used in said mixing in step (a).

[0075]

[0085] Item 4. The method of item 2, wherein if the residual PVOH content determined in step (b) is less than the target residual PVOH content, said adjusting in step (c) comprises decreasing the amount of butyraldehyde used in said mixing in step (a).

[0076]

[0086] Item 5. The method of item 4, wherein reducing the amount of butyraldehyde used in the mixing in step (a) comprises extracting butyraldehyde.

[0077]

[0087] Item 6. The method of item 2, wherein the target residual PVOH content of the balanced PVB-containing composition is 14-50%, 15-25%, 16-22%, 18.0-19.0%, or about 18.7%.

[0078]

[0088] Item 7. The method of item 1, wherein the equilibrated PVB-containing composition is a solution and said determining in step (b) is carried out by cloud point measurement.

[0079]

[0089] Item 8. The method of item 1, wherein the equilibrated PVB-containing composition is a PVB resin and said determining in step (b) is performed using an infrared sensor.

[0080]

[0090] Item 9. The method of item 1, wherein the equilibrated PVB-containing composition is a PVB resin and said determining in step (b) is carried out by titration.

[0081]

[0091] Item 10. The method of item 1, wherein the PVB feed composition comprises post-consumer recycled PVB.

[0082]

[0092] Item 11. The method of item 1, wherein the PVB feed composition comprises post-industrial recycled PVB.

[0083]

[0093] Item 12. The method of item 1, wherein the PVB feed composition comprises virgin PVB.

[0084]

[0094] Item 13. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVOH content than the second PVB-containing composition.

[0085]

[0095] Item 14. The method of item 13, wherein the relative difference between the residual PVOH content of the first PVB-containing composition and the residual PVOH content of the second PVB-containing composition is 2 to 10 wt.%.

[0086]

[0096] Item 15. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different aldehyde content than the second PVB-containing composition.

[0087]

[0097] Item 16. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different vinyl acetate content than the second PVB-containing composition.

[0088]

[0098] Item 17. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different plasticizer content than the second PVB-containing composition.

[0089]

[0099] Item 18. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different plasticizer type than the second PVB-containing composition.

[0090]

[0100] Item 19. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different molecular weight than the second PVB-containing composition.

[0091]

[0101] Item 20. The method of item 1, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different additive than the second PVB-containing composition, and the additive is selected from one or more of the following: adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants.

[0092]

[0102] Item 21. The method of item 1, wherein when the equilibrated PVB-containing composition is mixed with 20 phr of a plasticizer to form a PVB resin, and the PVB resin is formed into a 0.772 mm PVB layer and placed between two sheets of 2.3 mm glass to form a laminated glass panel, the laminated glass panel has a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%.

[0093]

[0103] Item 22. The method of item 1, wherein the solvent comprises an alcohol.

[0094]

[0104] Item 23. The method of item 1, wherein the catalyst comprises sulfuric acid.

[0095]

[0105] Item 24. The method of item 1, wherein the mixing in step (a) comprises heating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0096]

[0106] Item 25. The method of item 1, wherein the mixing in step (a) comprises agitating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0097]

[0107] Item 26. The method of item 1, further comprising filtering the equilibrated PVB-containing composition to remove solids.

[0098]

[0108] Item 27. The method of item 1, further comprising neutralizing the equilibrated PVB-containing composition by adding a base.

[0099]

[0109] Item 28. The method of item 27, wherein the base comprises potassium hydroxide.

[0100]

[0110] Item 29. The method of item 1, further comprising precipitating the equilibrated PVB-containing composition to obtain a PVB resin.

[0101]

[0111] Item 30. The method of item 29, further comprising the step of drying the PVB resin.

[0102]

[0112] Item 31. The method of item 30, further comprising washing the PVB resin to remove salt impurities.

[0103]

[0113] Item 32. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) establishing a target residual polyvinyl alcohol (PVOH) content; (b) combining the PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to form an equilibrated PVB-containing composition, the PVB feed composition comprising at least two different PVB-containing compositions; (c) measuring the residual PVOH content of the equilibrated PVB-containing composition; (d) adjusting the amount of butyraldehyde used in said combination in step (b) based on a comparison of the target residual PVOH content to the residual PVOH content measured in step (c). A method comprising:

[0104]

[0114] Item 33. The method of item 32, wherein said adjusting in step (d) comprises increasing the amount of butyraldehyde used in said combination in step (b) if the residual PVOH content measured in step (c) is greater than the target residual PVOH content established in step (a).

[0105]

[0115] Item 34. The method of item 32, wherein said adjusting in step (d) comprises decreasing the amount of butyraldehyde used in said combination in step (b) if the residual PVOH content measured in step (c) is less than the target residual PVOH content established in step (a).

[0106]

[0116] Item 35. The method of item 34, wherein reducing the amount of butyraldehyde used in the combination in step (b) comprises extracting butyraldehyde.

[0107]

[0117] Item 36. The method of item 32, wherein the target residual PVOH content is 14-50 wt.%, 15-25 wt.%, 16-22 wt.%, 18.0-19.0 wt.%, or about 18.7 wt.%.

[0108]

[0118] Item 37. The method of item 32, wherein the equilibrated PVB-containing composition is a solution and said measuring in step (c) is carried out by cloud point measurement.

[0109]

[0119] Item 38. The method of item 32, wherein the equilibrated PVB-containing composition is a PVB resin and the measuring in step (c) is performed using an infrared sensor.

[0110]

[0120] Item 39. The method of item 32, wherein the equilibrated PVB-containing composition is a PVB resin and the measuring in step (c) is carried out by titration.

[0111]

[0121] Item 40. The method of item 32, wherein the PVB feed composition comprises post-consumer recycled PVB.

[0112]

[0122] Item 41. The method of item 32, wherein the PVB feed composition comprises post-industrial recycled PVB.

[0113]

[0123] Item 42. The method of item 32, wherein the PVB feed composition comprises virgin PVB.

[0114]

[0124] Item 43. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVOH content than the second PVB-containing composition.

[0115]

[0125] Item 44. The method of item 43, wherein the relative difference between the residual PVOH content of the first PVB-containing composition and the residual PVOH content of the second PVB-containing composition is 2 to 10 wt.%.

[0116]

[0126] Item 45. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVB content than the second PVB-containing composition.

[0117]

[0127] Item 46. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different vinyl acetate content than the second PVB-containing composition.

[0118]

[0128] Item 47. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different plasticizer content than the second PVB-containing composition.

[0119]

[0129] Item 48. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different type of plasticizer than the second PVB-containing composition.

[0120]

[0130] Item 49. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different molecular weight than the second PVB-containing composition.

[0121]

[0131] Item 50. The method of item 32, wherein the at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different additive than the second PVB-containing composition, and the additive is selected from one or more of the following: adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants.

[0122]

[0132] Item 51. The method of item 32, wherein when the equilibrated PVB-containing composition is mixed with 20 phr of a plasticizer to form a PVB resin, and the PVB resin is formed into a 0.772 mm PVB layer and placed between two sheets of 2.3 mm glass to form a laminated glass panel, the laminated glass panel has a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%.

[0123]

[0133] Item 52. The method of item 32, wherein the solvent comprises an alcohol.

[0124]

[0134] Item 53. The method of item 32, wherein the catalyst comprises sulfuric acid.

[0125]

[0135] Item 54. The method of item 32, wherein the combining in step (b) comprises heating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0126]

[0136] Item 55. The method of item 32, wherein the combining in step (b) comprises agitating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0127]

[0137] Item 56. The method of item 32, further comprising filtering the equilibrated PVB-containing composition to remove solids.

[0128]

[0138] Item 57. The method of item 32, further comprising neutralizing the equilibrated PVB-containing composition by adding a base.

[0129]

[0139] Item 58. The method of item 57, wherein the base comprises potassium hydroxide.

[0130]

[0140] Item 59. The method of item 32, further comprising precipitating the equilibrated PVB-containing composition to obtain a PVB resin.

[0131]

[0141] Item 60. The method of item 59, further comprising the step of drying the PVB resin.

[0132]

[0142] Item 61. The method of item 60, further comprising washing the PVB resin to remove salt impurities.

[0133]

[0143] Item 62. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition, the PVB feed composition having a molecular weight greater than 200K Daltons; (b) producing a PVB resin from the equilibrated PVB-containing composition, the PVB resin having a molecular weight at least 25 K Daltons less than the molecular weight of the PVB feed composition; A method comprising:

[0134]

[0144] Item 63. The method of item 62, wherein the PVB feed composition has a molecular weight of greater than 225K, greater than 250K, greater than 275K, or greater than 300K.

[0135]

[0145] Item 64. The method of item 62, wherein the PVB resin has a molecular weight at least 30K, at least 40K, at least 50K, at least 60K, at least 70K, at least 80K, at least 90K, or at least 100K Daltons less than the molecular weight of the PVB feed composition.

[0136]

[0146] Item 65. The method of item 62, wherein the PVB resin has a viscosity of less than 230 cps, less than 220 cps, less than 210 cps, and / or less than 200 cps.

[0137]

[0147] Item 66. The method of item 62, wherein the PVB resin has a residual polyvinyl alcohol (PVOH) content percent of 14-50%, 15-25%, 16-22%, 18.0-19.0%, or about 18.7%.

[0138]

[0148] Item 67. The method of item 62, wherein the PVB feed composition comprises post-consumer recycled PVB.

[0139]

[0149] Item 68. The method of item 62, wherein the PVB feed composition comprises recycled off-cuts PVB.

[0140]

[0150] Item 69. The method of item 62, wherein the PVB feed composition comprises virgin PVB.

[0141]

[0151] Item 70. The method of item 62, wherein the PVB-feeding composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVB content than the second PVB-containing composition.

[0142]

[0152] Item 71. The method of item 62, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVOH content than the second PVB-containing composition.

[0143]

[0153] Item 72. The method of item 62, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different vinyl acetate content than the second PVB-containing composition.

[0144]

[0154] Item 73. The method of item 62, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different plasticizer content than the second PVB-containing composition.

[0145]

[0155] Item 74. The method of item 62, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different plasticizer type than the second PVB-containing composition.

[0146]

[0156] Item 75. The method of item 62, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different molecular weight than the second PVB-containing composition.

[0147]

[0157] Item 76. The method of item 62, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different additive than the second PVB-containing composition, the additive being selected from one or more of the following: adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants.

[0148]

[0158] Item 77. The method of item 62, wherein when the PVB resin is formed into a 0.772 mm PVB layer and placed between two sheets of 2.3 mm glass to form a laminated glass panel, the laminated glass panel has a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%.

[0149]

[0159] Item 78. The method of item 62, wherein the solvent comprises an alcohol.

[0150]

[0160] Item 79. The method of item 62, wherein the catalyst comprises sulfuric acid.

[0151]

[0161] Item 80. The method of item 62, wherein the mixing in step (a) comprises heating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0152]

[0162] Item 81. The method of item 62, wherein the mixing in step (a) comprises agitating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0153]

[0163] Item 82. The method of item 62, further comprising filtering the equilibrated PVB-containing composition to remove solids.

[0154]

[0164] Item 83. The method of item 62, further comprising neutralizing the equilibrated PVB-containing composition by adding a base, the base comprising potassium hydroxide.

[0155]

[0165] Item 84. The method of item 62, wherein the producing of step (b) comprises precipitating the equilibrated PVB-containing composition to obtain the PVB resin.

[0156]

[0166] Item 85. The method of item 62, further comprising the step of drying the PVB resin.

[0157]

[0167] Item 86. The method of item 62, further comprising the step of washing the PVB resin to remove salt impurities.

[0158]

[0168] Item 87. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) combining and heating a PVB feed composition, a solvent, a catalyst, and optionally butyraldehyde to produce an equilibrated PVB-containing composition, wherein the PVB feed composition has a molecular weight greater than 200K Daltons; (b) precipitating the equilibrated PVB-containing composition to produce a PVB resin, the PVB resin having a molecular weight at least 25K less than the molecular weight of the PVB feed composition; A method comprising:

[0159]

[0169] Item 88. The method of item 87, wherein the PVB feed composition has a molecular weight of greater than 225K, greater than 250K, greater than 275K, or greater than 300K Daltons.

[0160]

[0170] Item 89. The method of item 87, wherein the PVB resin has a molecular weight at least 30K, at least 40K, at least 50K, at least 60K, at least 70K, at least 80K, at least 90K, or at least 100K Daltons less than the molecular weight of the PVB feed composition.

[0161]

[0171] Item 90. The method of item 87, wherein the PVB resin has a viscosity of less than 230 cps, less than 220 cps, less than 210 cps, and / or less than 200 cps.

[0162]

[0172] Item 91. The method of item 87, wherein the PVB resin has a residual polyvinyl alcohol (PVOH) content percent of 14-50%, 15-25%, 16-22%, 18.0-19.0%, or about 18.7%.

[0163]

[0173] Item 92. The method of item 87, wherein the PVB feed composition comprises post-consumer recycled PVB.

[0164]

[0174] Item 93. The method of item 87, wherein the PVB feed composition comprises recycled off-cuts PVB.

[0165]

[0175] Item 94. The method of item 87, wherein the PVB supply composition comprises virgin PVB.

[0166]

[0176] Item 95. The method of item 87, wherein the PVB-feeding composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVB content than the second PVB-containing composition.

[0167]

[0177] Item 96. The method of item 87, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVOH content than the second PVB-containing composition.

[0168]

[0178] Item 97. The method of item 87, wherein the PVB-feeding composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different vinyl acetate content than the second PVB-containing composition.

[0169]

[0179] Item 98. The method of item 87, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different plasticizer content than the second PVB-containing composition.

[0170]

[0180] Item 99. The method of item 87, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different plasticizer type than the second PVB-containing composition.

[0171]

[0181] Item 100. The method of item 87, wherein the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different molecular weight than the second PVB-containing composition.

[0172]

[0182] Item 101. The method of item 87, wherein the PVB-feeding composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different additive than the second PVB-containing composition, the additive being selected from one or more of the following: adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants.

[0173]

[0183] Item 102. The method of item 87, wherein when the PVB resin is formed into a 0.772 mm PVB layer and placed between two sheets of 2.3 mm glass to form a laminated glass panel, the laminated glass panel has a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%.

[0174]

[0184] Item 103. The method of item 87, wherein the solvent comprises an alcohol.

[0175]

[0185] Item 104. The method of item 87, wherein the catalyst comprises sulfuric acid.

[0176]

[0186] Item 105. The method of item 87, wherein the combining and heating in step (a) comprises agitating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

[0177]

[0187] Item 106. The method of item 87, further comprising filtering the equilibrated PVB-containing composition to remove solids.

[0178]

[0188] Item 107. The method of item 87, further comprising neutralizing the equilibrated PVB-containing composition by adding a base, the base comprising potassium hydroxide.

[0179]

[0189] Item 108. The method of item 87, further comprising the step of drying the PVB resin.

[0180]

[0190] Item 109. The method of item 87, further comprising washing the PVB resin to remove salt impurities.

[0181]

[0191] Item 110. Recycled PVB formed by any of the methods of items 1 to 109.

[0182]

[0192] Item 111. A resin layer containing recycled PVB of Item 110.

[0183]

[0193] Item 112. An intermediate layer comprising the resin layer of Item 111.

[0184]

[0194] Item 113. The intermediate layer of item 112, further comprising a second resin layer, or 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.

[0185]

[0195] Item 114. A laminate comprising a first substrate, an intermediate layer of item 112 or 113, 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) combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to form an equilibrated PVB-containing composition, wherein the PVB feed composition comprises at least two different PVB-containing compositions; (b) determining the residual polyvinyl alcohol (PVOH) content of the equilibrated PVB-containing composition; (c) adjusting the amount of butyraldehyde used in said mixing of step (a) based on the residual PVOH content determined in step (b); A method comprising:

2. 10. The method of claim 1, further comprising the step of establishing a target residual PVOH content for the equilibrated PVB-containing composition.

3. 3. The method of claim 2, wherein if the residual PVOH content determined in step (b) is greater than a target residual PVOH content, the adjusting in step (c) comprises increasing the amount of butyraldehyde used in the blending of step (a), or if the residual PVOH content determined in step (b) is less than a target residual PVOH content, the adjusting in step (c) comprises decreasing the amount of butyraldehyde used in the blending of step (a), wherein decreasing the amount of butyraldehyde used in the blending of step (a) comprises extracting butyraldehyde.

4. 10. The method of claim 1, wherein the equilibrated PVB-containing composition is a solution and said determining in step (b) is performed by cloud point measurement, or wherein the equilibrated PVB-containing composition is a PVB resin and said determining in step (b) is performed using an infrared sensor or by titration.

5. 10. The method of claim 1, wherein the mixing in step (a) comprises heating the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde, or the mixing in step (a) comprises stirring the PVB feed composition, the solvent, the catalyst, and / or the butyraldehyde.

6. 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) establishing a target residual polyvinyl alcohol (PVOH) content; (b) combining the PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to form an equilibrated PVB-containing composition, wherein the PVB feed composition comprises at least two different PVB-containing compositions; (c) measuring the residual PVOH content of the equilibrated PVB-containing composition; (d) adjusting the amount of butyraldehyde used in said combination in step (b) based on a comparison of the target residual PVOH content with the residual PVOH content measured in step (c); A method comprising:

7. 7. The method of claim 6, wherein if the residual PVOH content measured in step (c) is greater than the target residual PVOH content established in step (a), the adjusting in step (d) comprises increasing the amount of butyraldehyde used in the combination of step (b); or if the residual PVOH content measured in step (c) is less than the target residual PVOH content established in step (a), the adjusting in step (d) comprises decreasing the amount of butyraldehyde used in the combination of step (b), wherein decreasing the amount of butyraldehyde used in the combination of step (b) comprises extracting butyraldehyde.

8. 7. The method of claim 6, wherein the equilibrated PVB-containing composition is a solution and the measuring in step (c) is performed by cloud point measurement, or the equilibrated PVB-containing composition is a PVB resin and the measuring in step (c) is performed using an infrared sensor, or the equilibrated PVB-containing composition is a PVB resin and the measuring in step (c) is performed by titration.

9. 7. The method of claim 6, wherein the combining in step (b) comprises heating the PVB feed composition, solvent, catalyst, and / or butyraldehyde, or the combining in step (b) comprises agitating the PVB feed composition, solvent, catalyst, and / or butyraldehyde.

10. 10. The method of claim 1, wherein the target residual PVOH content is 14-50 wt.%, 15-25 wt.%, 16-22 wt.%, 18.0-19.0 wt.%, or about 18.7 wt.%.

11. The at least two different PVB-containing compositions include a first PVB-containing composition and a second PVB-containing composition, the first PVB-containing composition having a different PVOH content than the second PVB-containing composition, and the relative difference between the residual PVOH content of the first PVB-containing composition and the residual PVOH content of the second PVB-containing composition is 2 to 10 wt. %, or the at least two different PVB-containing compositions comprise a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different aldehyde content than the second PVB-containing composition, or the at least two different PVB-containing compositions comprise a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different vinyl acetate content than the second PVB-containing composition, or the at least two different PVB-containing compositions comprise a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different plasticizer content than the second PVB-containing composition, or the at least two different PVB-containing compositions comprise a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different plasticizer content than the second PVB-containing composition, or 10. The method of claim 1, comprising a PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different plasticizer type than the second PVB-containing composition, or the at least two different PVB-containing compositions comprise the first PVB-containing composition and the second PVB-containing composition, wherein the first PVB-containing composition has a different molecular weight than the second PVB-containing composition, or the at least two different PVB-containing compositions comprise the first PVB-containing composition and the second PVB-containing composition, wherein the first PVB-containing composition has a different additive than the second PVB-containing composition, the additive being selected from one or more of the following: adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants.

12. 10. The method of claim 1, wherein when the equilibrated PVB-containing composition is mixed with 20 phr of plasticizer to form a PVB resin, the PVB resin is formed into a 0.772 mm PVB layer and placed between two 2.3 mm sheets of glass to form a laminated glass panel, the laminated glass panel has a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%.

13. 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) combining a PVB feed composition with a solvent, a catalyst, and optionally butyraldehyde to form an equilibrated PVB-containing composition, wherein the PVB feed composition has a molecular weight greater than 200K Daltons; (b) producing a PVB resin from the equilibrated PVB-containing composition, the PVB resin having a molecular weight at least 25 K Daltons less than the molecular weight of the PVB feed composition; A method comprising:

14. 14. The method of claim 13, wherein the mixing in step (a) comprises heating the PVB feed composition, solvent, catalyst, and / or butyraldehyde; the mixing in step (a) comprises stirring the PVB feed composition, solvent, catalyst, and / or butyraldehyde; or the forming in step (b) comprises precipitating the equilibrated PVB-containing composition to obtain the PVB resin.

15. 1. A method for recovering poly(vinyl butyral) (PVB), comprising: (a) combining and heating a PVB feed composition, a solvent, a catalyst, and optionally butyraldehyde to form an equilibrated PVB-containing composition, wherein the PVB feed composition has a molecular weight greater than 200 K Daltons; (b) precipitating the equilibrated PVB-containing composition to produce a PVB resin, the PVB resin having a molecular weight at least 25K less than the molecular weight of the PVB feed composition; A method comprising:

16. 16. The method of claim 15, wherein the combining and heating of step (a) comprises agitating the PVB feed composition, solvent, catalyst, and / or butyraldehyde.

17. 16. The method of claim 15, wherein the PVB feed composition has a molecular weight greater than 225K, greater than 250K, greater than 275K, or greater than 300K; or the PVB resin has a molecular weight at least 30K, at least 40K, at least 50K, at least 60K, at least 70K, at least 80K, at least 90K, or at least 100K Daltons less than the molecular weight of the PVB feed composition; or the PVB resin has a viscosity less than 230 cps, less than 220 cps, less than 210 cps, and / or less than 200 cps; or the PVB resin has a percent residual polyvinyl alcohol (PVOH) content of 14-50%, 15-25%, 16-22%, 18.0-19.0%, or about 18.7%.

18. The PVB feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different PVB content than the second PVB-containing composition; or the PVB feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different PVOH content than the second PVB-containing composition; or the PVB feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different PVOH content than the second PVB-containing composition. the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different vinyl acetate content than the second PVB-containing composition; or the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different plasticizer content than the second PVB-containing composition; or the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, wherein the first PVB-containing composition has a different plasticizer content than the second PVB-containing composition. The PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition having a different plasticizer type than a second PVB-containing composition, or the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition, and the first PVB-containing composition has a different molecular weight than the second PVB-containing composition, or the PVB-feed composition comprises at least two different PVB-containing compositions, including a first PVB-containing composition and a second PVB-containing composition.

16. The method of claim 15, wherein the PVB-containing composition comprises a composition, wherein the first PVB-containing composition has different additives than the second PVB-containing composition, and the additives are selected from one or more of the following: adhesion control agents, UV stabilizers, antioxidants, IR absorbers, and colorants; or wherein when the PVB resin is formed into a 0.772 mm PVB layer and placed between two 2.3 mm pieces of glass to form a laminated glass panel, the laminated glass panel has a haze of less than 5%, less than 2%, less than 1%, less than 0.5%, or less than 0.25%.

19. 10. The method of claim 1, wherein the PVB feed composition comprises post-consumer recycled PVB, or the PVB feed composition comprises post-industrial recycled PVB, or the PVB feed composition comprises recycled off-cuts PVB, or the PVB feed composition comprises virgin PVB, or the solvent comprises an alcohol, or the catalyst comprises sulfuric acid.

20. 10. The method of claim 1, further comprising filtering the equilibrated PVB-containing composition to remove solids, or further comprising neutralizing the equilibrated PVB-containing composition by adding a base, the base comprising potassium hydroxide, or further comprising precipitating the equilibrated PVB-containing composition to obtain the PVB resin, or further comprising drying the PVB resin, or further comprising washing the PVB resin to remove salt impurities.

21. 21. Recycled PVB formed by the method of any one of claims 1 to 20.

22. A resin layer comprising the recycled PVB of claim 21.

23. An intermediate layer comprising the resin layer of claim 22.

24. 24. The intermediate layer of claim 23, 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.

25. 24. A laminate comprising a first substrate, the intermediate layer of claim 23, and a second substrate, wherein the intermediate layer is between the first substrate and the second substrate.

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