High refractive index polyvinyl acetal resin modified with cyclic aldehydes

Abstract

Modified polyvinyl acetal resins containing residues of cyclic aldehydes are provided for use in forming interlayers for making laminated glass. The interlayers described herein exhibit desirable optical and acoustic properties and are more easily recycled than those without the modified polyvinyl acetal resin.

Description

[Technical Field]

[0001] Safety glass used in automotive windshields and architectural applications can include two laminated panes of glass with a plasticized polymer interlayer between the panes. Polyvinyl butyral ("PVB") can be the primary component of the polymer interlayer. Typically, PVB interlayers are single-ply, but in recent years, the market has seen an increase in sales of multi-layer polyvinyl butyral interlayers for laminated glass. Multi-layer interlayers can enhance sound insulation due to the presence of a soft "core" layer positioned between two hard "skin" layers. Typically, the PVB resin in the core layer has a different content composition than the PVB compound in the skin layers, and can have, for example, different residual hydroxyl and / or acetyl content.

[0002] During the manufacture of monolithic interlayers, it is common for off-grade and / or trim materials to be reused in the sheet manufacturing process because the monolithic interlayer contains only one type of polyvinyl butyral. However, due to the difference in polyvinyl butyral composition between the skin and core layers of multilayer PVB interlayers, multilayer film scrap cannot be re-extruded. If left as is, the resulting blend resin composition exhibits high levels of haze, resulting in a final interlayer product with unacceptable visual quality. As a result, large-scale recycling of multilayer interlayer materials has not been successful.

[0003] Therefore, it would be desirable to have a commercial-scale process and system for recycling multilayer polyvinyl butyral scrap (e.g., from off-grade end products, trim from manufacturing processes, and even discarded laminated glass) in an economically and environmentally beneficial manner. There is a need for resin compositions, including PVB resin compositions, that can be used in multilayer interlayers that do not exhibit haze upon re-extrusion and are therefore more recyclable. Summary of the Invention

[0004] In one aspect, the present technology relates to a polyvinyl acetal resin composition including a polyvinyl acetal resin component including the residue of at least one cyclic aldehyde having an unsaturated 5- or 6-membered ring group, and another polyvinyl acetal resin component including the residue of at least one C3-C8 aliphatic aldehyde, and at least one plasticizer.

[0005] In one aspect, the present technology relates to a polyvinyl acetal resin composition comprising one or more polyvinyl acetal resins, the polyvinyl acetal resin component comprising at least one residue of at least one cyclic aldehyde comprising at least one heterocyclic group, and at least one plasticizer, wherein the composition comprises less than 5 weight percent of a resin other than the polyvinyl acetal resin.

[0006] In one aspect, the present technology relates to an interlayer including: a first resin layer including a first polyvinyl acetal resin and at least one plasticizer; and a second resin layer including a polyvinyl acetal resin component including a residue of at least one cyclic aldehyde, another polyvinyl acetal resin component including a residue of at least one C3-C8 aliphatic aldehyde, and at least one plasticizer, wherein the cyclic aldehyde includes (a) a conjugated 5- or 6-membered ring and / or (b) a heterocycle.

[0007] In one aspect, the present technology relates to a method for producing a polyvinyl acetal resin component, comprising at least one of the following steps (a) and (b): (a) acetalizing polyvinyl alcohol with at least one C3-C8 aliphatic aldehyde and at least one cyclic aldehyde to form a modified polyvinyl acetal resin, wherein the cyclic aldehyde comprises (i) an unsaturated 5- or 6-membered ring and / or (ii) a heterocycle, and / or (b) blending the polyvinyl acetal resin comprising residues of a cyclic aldehyde and / or a heterocycle with another polyvinyl acetal resin comprising at least 50 weight percent residues of a C3-C8 aliphatic aldehyde to form a blended polyvinyl acetal resin composition.

[0008] In one aspect, the present technology relates to a blended polyvinyl acetal resin composition comprising: a first polyvinyl acetal resin having a residual hydroxyl content of at least 16 weight percent; a polyvinyl acetal resin component having residues of at least one cyclic aldehyde, the cyclic aldehyde comprising (a) an unsaturated 5- or 6-membered ring and / or (b) a heterocyclic ring; and at least one plasticizer; wherein the resin composition has a haze value of less than 1.

[0009] Various embodiments of the present technology are described in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block flow diagram showing the main steps / zones of a process / facility for producing modified polyvinyl acetal resin, according to an embodiment of the present technology. [Figure 2] 1 is a cross section of a multi-layer interlayer in accordance with an embodiment of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present inventors have discovered a polyvinyl acetal resin composition suitable for use in forming interlayers suitable for use in a variety of applications, which can also be recycled in large quantities. In particular, the inventors have discovered that multilayer interlayers having a core resin layer with a higher refractive index can exhibit lower haze values ​​when blended with other polyvinyl acetal resins, such as those used to form skin layers. As a result, such multilayer interlayers can be recycled, for example, by combining multilayer scrap with the skin layer resin and re-extruding the combination to form a recycled interlayer. The novel polyvinyl acetal resin used in the core layer contains cyclic aldehyde side chains extending from the polymer backbone. Modified polyvinyl acetal resins can be formed by co-acetalizing at least one cyclic aldehyde with at least one C3-C8 aliphatic aldehyde, and the resulting modified polyvinyl acetal resin can be blended with at least one plasticizer to form a modified resin composition suitable for use in multilayer interlayers.

[0012] Referring first to FIG. 1, a block flow diagram illustrating the main steps / zones of a process / facility for forming a modified polyvinyl acetal resin according to an embodiment of the present technology is provided. As shown in FIG. 1, vinyl acetate can be polymerized to obtain polyvinyl acetate, which can then be hydrolyzed to obtain polyvinyl alcohol. At least a portion of the polyvinyl alcohol can then be reacted with at least one cyclic aldehyde to form a modified polyvinyl acetal resin. The acetalization reaction can be carried out by suspension or solution polymerization in the presence of a catalyst, which can be an acid or a base. The resulting modified polyvinyl acetal resin can then be isolated, stabilized, and dried according to known methods, such as those described in U.S. Pat. Nos. 2,282,057 and 2,282,026, and Wade, B. 2016, Vinyl Acetal Polymers, Encyclopedia of Polymer Science and Technology. 1-22 (online, copyright 2016 John Wiley & Sons, Inc.).

[0013] As used herein, the term "modified polyvinyl acetal resin" refers to a polyvinyl acetal resin containing residues of at least one cyclic aldehyde. The modified polyvinyl acetal resin may have a total acetalization percentage of at least 50 weight percent, at least 55 weight percent, at least 60 weight percent, at least 65 weight percent, at least 70 weight percent, at least 75 weight percent, at least 80 weight percent, at least 85 weight percent, or at least 90 weight percent, as measured according to ASTM D-1396, unless otherwise specified. The total amount of aldehyde residues in the polyvinyl acetal resin can be collectively referred to as the acetal component, and the remainder of the polyvinyl acetal resin is residual vinyl alcohol (hydroxyl) groups and residual acetate (acetyl) groups, which are described in further detail below. As used herein, the term "unmodified polyvinyl acetal resin" refers to a polyvinyl acetal resin that does not contain residues of cyclic vinyl acetal monomers and that contains at least 99 weight percent of vinyl acetate, polyvinyl alcohol, and residues of at least one aldehyde.

[0014] The modified polyvinyl acetal resin may contain at least 1 weight percent, at least 2 weight percent, at least 5 weight percent, at least 10 weight percent, at least 15 weight percent, or at least 20 weight percent, and / or no more than 50 weight percent, no more than 45 weight percent, no more than 40 weight percent, no more than 35 weight percent, no more than 30 weight percent, no more than 25 weight percent, or no more than 20 weight percent of residues of one or more cyclic aldehydes, based on the total moles of aldehyde residues in the polyvinyl acetal resin. Alternatively, the modified polyvinyl acetal resin comprises at least 45 weight percent, at least 50 weight percent, at least 55 weight percent, at least 60 weight percent, at least 65 weight percent, at least 70 weight percent, at least 75 weight percent, at least 80 weight percent, at least 85 weight percent, at least 90 weight percent, at least 95 weight percent, or at least 99 weight percent, or up to 100 weight percent, and / or no more than 99 weight percent, no more than 95 weight percent, no more than 90 weight percent, no more than 85 weight percent, no more than 80 weight percent, no more than 75 weight percent, no more than 70 weight percent, no more than 65 weight percent, no more than 60 weight percent, no more than 55 weight percent, or no more than 50 weight percent of residues of cyclic aldehydes, based on the total weight of aldehyde residues in the modified polyvinyl acetal resin.

[0015] The cyclic aldehyde may contain at least one, two, or three ring groups. One or more ring groups may individually contain at least 5, at least 6, at least 8, or at least 10 atoms per ring, and / or no more than 30, 28, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 5, 4, or 3 carbon atoms. In some cases, the ring may contain only carbon atoms. At least one of the ring groups may be unsaturated, and in some cases, it may be conjugated or aromatic. In some cases, the cyclic aldehyde may contain at least one unsaturated five- or six-membered ring group.

[0016] In some embodiments, the cyclic aldehyde may contain a heterocycle having at least one atom other than carbon in the main ring structure. In the case of a heterocycle, the ring group may contain at least one heteroatom selected from the group consisting of sulfur (S), phosphorus (P), nitrogen (N), and oxygen (O). In some cases, the heterocycle may be unsaturated, while in other cases, the heterocycle may be conjugated. The heterocycle may be saturated. The cyclic aldehyde may contain one or more heterocycles.

[0017] Examples of specific cyclic aldehydes suitable for use in embodiments of the present technology may include, but are not limited to, furfural, substituted furfural, hydroxymethylfurfural (HMF), 2-thiophene carboxyaldehyde, 3-thiophene carboxyaldehyde, 2-pyridine carboxyaldehyde, 2-acetylthiophene, 2-pyrrole-2-carboxyaldehyde, 5-bromo-2-thiophene carboxyaldehyde, benzo(b)thiophene-2-carboxyaldehyde, 4-pyridine carboxyaldehyde, and 3-pyridine carboxyaldehyde.In some embodiments, the cyclic aldehyde may not be furfural or its derivatives.

[0018] The cyclic aldehyde may have a molecular weight of at least 1.500, at least 1.505, at least 1.510, at least 1.515, at least 1.520, at least 1.525, at least 1.530, at least 1.535, at least 1.540, at least 1.545, at least 1.550, at least 1.555, at least 1.560, at least 1.565, at least 1.570, at least 1.575, at least 1.580, at least 1.585, at least 1.590, at least 1.595, at least 1.600, at least 1.605, at least 1.610, at least 1.615, at least 1.620, at least 1.625 and / or a refractive index of 2.000 or less, 1.950 or less, 1.900 or less, 1.850 or less, 1.800 or less, 1.750 or less, 1.700 or less, 1.650 or less, 1.600 or less, 1.590 or less, 1.580 or less, 1.575 or less, 1.570 or less, 1.565 or less, 1.560 or less, 1.555 or less, 1.550 or less, 1.545 or less, 1.540 or less, 1.535 or less, 1.530 or less, or 1.525 or less.

[0019] In some embodiments, the modified polyvinyl acetal resin may further comprise the residue of at least one C1-C10 aliphatic aldehyde, C3-C8 aliphatic aldehyde, C3-C6 aliphatic aldehyde, or C4 aliphatic aldehyde. Examples of suitable aldehydes may include, but are not limited to, n-butyraldehyde, isobutyraldehyde, 2-methylvaleraldehyde, n-hexylaldehyde, 2-ethylhexylaldehyde, n-octylaldehyde, and combinations thereof. The modified polyvinyl acetal resin can comprise at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, or at least 95 weight percent, or in the range of 20 to 90, 30 to 80, or 40 to 70 weight percent, based on the total weight of aldehyde residues in the polyvinyl acetal resin. Alternatively, the modified polyvinyl acetal resin can comprise less than 50 weight percent, less than 45 weight percent, less than 40 weight percent, less than 35 weight percent, less than 30 weight percent, less than 25 weight percent, less than 20 weight percent, less than 15 weight percent, less than 10 weight percent, less than 5 weight percent, less than 2 weight percent, less than 1 weight percent, or less than 0.5 weight percent, based on the total weight of aldehyde residues in the polyvinyl acetal resin. In some cases, the modified polyvinyl acetal resin may be free of residues of C3-C8 aliphatic aldehydes.

[0020] Although this specification generally describes a single polyvinyl acetal resin having residues (or moieties) of two or more aldehydes, it should be understood that in some cases, an equivalent physical blend of two polyvinyl acetal resins, each containing residues of one of the aldehydes, may yield results similar to a single modified polyvinyl acetal resin. As used herein, the term "polyvinyl acetal resin component" may refer to an individual polyvinyl acetal resin present in a physical blend of two or more resins, or to the acetal moieties present on a single polyvinyl acetal resin.

[0021] In some cases, at least one resin composition, layer, or interlayer described herein may include a polyvinyl acetal resin component that includes residues of a cyclic aldehyde and another polyvinyl acetal resin component that does not include residues of a cyclic aldehyde (and may include, for example, residues of a C3-C8 aliphatic aldehyde). This polyvinyl acetal resin component may refer to either (1) a blend of two different polyvinyl acetal resins (e.g., one with cyclic aldehyde residues and the other without), or (2) a single polyvinyl acetal resin with two different acetal moieties (e.g., one with cyclic aldehyde residues and the other without). In either case, the polyvinyl acetal resin component (either as a single polyvinyl acetal resin or as a blend of two or more resins) may be combined with one or more plasticizers and optionally other additives to provide a single plasticized composition, layer, or interlayer according to embodiments of the present technology. As noted above, a polyvinyl acetal resin containing residues of a cyclic aldehyde may be referred to as a "modified polyvinyl acetal resin," regardless of whether it also contains residues of another aldehyde (e.g., a C3-C8 aliphatic aldehyde). When blended, the polyvinyl acetal resin having residues of another aldehyde may have similar properties (e.g., hydroxyl content, acetate content, etc.) to the modified polyvinyl acetal resin present in the blend.

[0022] When forming a modified polyvinyl acetal resin containing residues (or moieties) of both a cyclic aldehyde and another aldehyde (e.g., a C3-C8 aliphatic aldehyde), the cyclic aldehyde and the other aldehyde (e.g., a C3-C8 aliphatic aldehyde) may be combined (not shown in FIG. 1 ) before being introduced into the acetalization step / zone, or the aldehydes may be added separately, as shown in FIG. 1 . If added separately, the aldehydes may be added simultaneously or sequentially. For example, in some cases, the C3-C8 aliphatic aldehyde may be added after the cyclic aldehyde has been added and at least partially reacted with the polyvinyl alcohol. If the modified polyvinyl acetal resin contains only residues of a cyclic aldehyde, it may be added at any suitable time to the reaction, and the C3-C8 aldehyde may not be added.

[0023] The modified polyvinyl acetal resin may have a residual hydroxyl content of at least 8, at least 8.5, at least 9, at least 9.5, at least 10, at least 10.5, at least 11, at least 11.5, at least 12, or at least 12.5 weight percent and / or no more than 16 weight percent, no more than 15.5 weight percent, no more than 15 weight percent, no more than 14.5 weight percent, no more than 14 weight percent, no more than 13.5 weight percent, no more than 13 weight percent, no more than 12.5 weight percent, or no more than 12 weight percent. Additionally or alternatively, the modified polyvinyl acetal resin may have a residual acetate content of at least 0.5, at least 1, at least 1.5, at least 2, at least 5, at least 10, at least 15, or at least 18 weight percent and / or no more than 35 weight percent, no more than 30 weight percent, no more than 25 weight percent, no more than 20 weight percent, no more than 15 weight percent, no more than 10 weight percent, no more than 8 weight percent, no more than 6 weight percent, no more than 5 weight percent, no more than 3 weight percent, no more than 2.5 weight percent, or no more than 2 weight percent.

[0024] As used herein, the terms "residual hydroxyl content" and "residual acetate content" refer to the amount of hydroxyl and acetate groups, respectively, remaining on a polyvinyl resin after the acetalization reaction is complete. In the process of hydrolyzing polyvinyl acetate, not all of the acetate groups are converted to hydroxyl groups, leaving residual acetate groups on the resin. Similarly, in the process of acetalizing polyvinyl alcohol, not all of the hydroxyl groups are converted to acetal groups, again leaving residual hydroxyl groups on the resin. As a result, most polyvinyl acetal resins contain both residual hydroxyl groups (as vinyl hydroxyl groups) and residual acetate groups (as vinyl acetate groups) as part of the polymer chain. Residual hydroxyl content and residual acetate content are expressed as weight percent based on the weight of the polymer resin and are measured according to ASTM D-1396, unless otherwise specified.

[0025] In some embodiments, the modified polyvinyl acetal resin may contain less than 5 weight percent, less than 3 weight percent, less than 2 weight percent, less than 1 weight percent, or less than 0.5 weight percent of residues other than residual hydroxyl groups, residual acetate groups, and residues of aldehydes in the polymer backbone. For example, the modified polyvinyl acetal resin may contain less than 5 weight percent, less than 3 weight percent, less than 2 weight percent, less than 1 weight percent, or less than 0.5 weight percent of residues of acrylics, butadienes, imides, and combinations thereof.

[0026] The modified polyvinyl acetal resin may have a molecular weight of at least 30,000, at least 50,000, at least 70,000, at least 100,000, at least 250,000, at least 500,000 daltons and / or no more than 1,000,000 daltons, no more than 750,000 daltons, no more than 600,000 daltons, no more than 550,000 daltons, no more than 500,000 daltons, no more than 450,000 daltons, or no more than 425,000 daltons, as measured by the size exclusion chromatography with low angle laser light scattering (SEC / LALLS) method of Cotts and Ouano. As used herein, the term "molecular weight" refers to weight average molecular weight (Mw). The molecular weight of the polyvinyl acetal resin can range from 50,000 to 1,000,000, 100,000 to 750,000, or 250,000 to 750,000 daltons.

[0027] The modified polyvinyl acetal resin may not be crosslinked. That is, in some cases, it may contain less than 250 parts per million (ppm) by weight, less than 200 ppm, less than 150 ppm, less than 100 ppm, less than 50 ppm, less than 25 ppm, less than 10 ppm, less than 5 ppm, less than 3 ppm, less than 2 ppm, or less than 1 ppm by weight of a dialdehyde crosslinker. Additionally or alternatively, the modified polyvinyl acetal resin may contain less than 2 weight percent, less than 1 weight percent, less than 0.5 weight percent, or less than 0.25 weight percent of an acidic crosslinker. In some cases, little or no (e.g., less than 5 phr, less than 2 phr, less than 1 phr, or less than 0.5 phr) of these crosslinkers may be added to the resin or its precursor during the process for forming the modified polyvinyl acetal resin described herein.

[0028] The modified polyvinyl acetal resin may have a viscosity of at least 1.480, at least 1.485, at least 1.486, at least 1.490, at least 1.495, at least 1.500, at least 1.505, at least 1.510, at least 1.515, at least 1.520, at least 1.525, at least 1.530, at least 1.535, at least 1.540, at least 1.545, at least 1.550, and / or 1.6 The refractive index may be 1.00 or less, 1.595 or less, 1.590 or less, 1.585 or less, 1.580 or less, 1.575 or less, 1.570 or less, 1.565 or less, 1.560 or less, 1.555 or less, 1.550 or less, 1.545 or less, 1.540 or less, 1.535 or less, 1.530 or less, 1.525 or less, 1.520 or less, 1.515 or less, 1.510 or less, 1.505 or less, 1.500 or less, 1.495 or less, 1.490 or less, or 1.488 or less.

[0029] Referring now to FIG. 2 , a schematic cross-section of an interlayer according to various embodiments of the present technology is shown. The interlayer shown in FIG. 2 is a multi-layer interlayer having, for example, a first resin layer 1, a second resin layer 2, and a third resin layer 3. As used herein, terms such as “first,” “second,” and “third” are used to describe various elements, but such elements should not be unnecessarily limited by these terms. These terms are used only to distinguish one element from another and do not necessarily imply a particular order or even a particular element. For example, unless contradictory, an element may be considered a “first” element in the description and a “second” element in the claims. Consistency will be maintained within the description and with respect to each independent claim, but such names are not necessarily intended to be consistent between them. In some cases, the interlayer may include four or more layers (embodiments not shown in FIG. 2 ).

[0030] As shown in Figure 2, the second resin layer 2 may be located adjacent to and between the first and third resin layers 1, 3. The second resin layer 2 may be referred to as the "core" or "inner" layer, and the first and third resin layers 1, 3 may be referred to as the "skin" or "outer" layers. When the intermediate layer includes more than three layers, the outermost layer may be referred to as the skin layer, and the innermost layer may be referred to as the core layer.

[0031] In one or more embodiments, at least one of the resin layers (e.g., skin layers 1 and 3 and / or core layer 2 shown in FIG. 2) can include at least one modified polyvinyl acetal resin as described above. The modified polyvinyl acetal resin can be present in both the skin and core layers in the same or different amounts, while in other cases, the modified polyvinyl acetal resin can be present only in the skin or core layers. In some embodiments, skin layers 1 and 3 can include at least 85, at least 90, at least 95, at least 97, or at least 99 weight percent unmodified polyvinyl acetal resin, and core layer 2 can include at least 85, at least 90, at least 95, at least 97, or at least 99 weight percent of at least one modified polyvinyl acetal resin comprising residues of a cyclic vinyl monomer. As used herein, the term "unmodified polyvinyl acetal resin" refers to a polyvinyl acetal resin that contains at least 99 percent by weight of residues of vinyl acetate, polyvinyl alcohol, and at least one aldehyde, and that contains no residues of cyclic vinyl acetal monomers.

[0032] In some embodiments, at least one of the resin layers of the multilayer interlayer may include at least one thermoplastic polymer in addition to a polyvinyl acetal (or modified polyvinyl acetal) resin. Examples of suitable thermoplastic polymers include, but are not limited to, polyvinyl acetal resin, polyurethane (PU), poly(ethylene-co-vinyl acetate) (EVA), polyvinyl chloride (PVC), poly(vinyl chloride-co-methacrylate), polyethylene, polyolefin, ethylene acrylic acid ester copolymer, poly(ethylene-co-butyl acrylate), silicone elastomer, epoxy resin, and acid copolymers such as ethylene / carboxylic acid copolymers and ionomers thereof derived from any of the above-listed polymers, and combinations thereof.

[0033] In some cases, the core layer 2 and / or the skin layers 1, 3 may be substantially free of resins other than polyvinyl acetal resin (or modified polyvinyl acetal resin). In some embodiments, at least one of the core layer and / or skin layers may include a resin other than a polyvinyl acetal resin (or modified polyvinyl acetal resin) in an amount of 20 weight percent or less, 15 weight percent or less, 10 weight percent or less, 5 weight percent or less, 4.5 weight percent or less, 4 weight percent or less, 3.5 weight percent or less, 3 weight percent or less, 2.5 weight percent or less, 2 weight percent or less, 1.5 weight percent or less, 1 weight percent or less, 0.5 weight percent or less, 0.1 weight percent or less, or 0.05 weight percent or less, based on the total weight of all resins, or may include less than 0.5, 0.3, 0.25, 0.20, 0.15, 0.10, 0.05, or 0.01 phr of a resin other than a polyvinyl acetal resin or resins (e.g., polyolefins, acrylic resins, block copolymers, etc.). In some cases, at least one of the layers may comprise only a single polyvinyl acetal resin, while in other cases, one or more of the layers may comprise a blend of two or more polyvinyl acetal resins. One or more of the skin 1, 3 and core layers may be continuous layers that do not contain islands or particles of other polymeric materials dispersed therein.

[0034] The polyvinyl acetal resin (or resin component or modified polyvinyl acetal resin or component) used in one or more layers of the multilayer interlayer can comprise the residue of any suitable aldehyde, and in some embodiments, can comprise at least one, or at least two, or three or more C1-C10 aldehydes, at least one C3-C8 aldehyde, at least one C3-C6 aldehyde, or a C4-C8 or C4 aliphatic aldehyde. Examples of suitable aldehydes can include, but are not limited to, propionaldehyde, n-butyraldehyde, isobutyraldehyde, 2-methylvaleraldehyde, n-hexylaldehyde, 2-ethylhexylaldehyde, n-octylaldehyde, and combinations thereof. In some embodiments, the polyvinyl acetal resin or resins used in a layer or layers may comprise at least 20, at least 30, at least 40, at least 50, at least 60, or at least 70 weight percent of residues of at least one C3-C8 aldehyde, and / or may comprise up to 90 weight percent, up to 85 weight percent, up to 80 weight percent, up to 75 weight percent, up to 70 weight percent, or up to 65 weight percent of at least one C3-C8 aldehyde, or in the range of 20 to 90, 30 to 80, or 40 to 70 weight percent of at least one C3-C8 aldehyde, based on the total weight of aldehyde residues of the resin. The C3-C8 aldehyde may be selected from the group described above or may be selected from the group consisting of n-butyraldehyde, isobutyraldehyde, 2-ethylhexylaldehyde, and combinations thereof.

[0035] In some embodiments, the polyvinyl acetal resin may be a polyvinyl butyral (PVB) resin or component (or modified PVB resin or component). In other embodiments, the polyvinyl acetal resin may be a polyvinyl n-butyral resin, which comprises primarily residues of n-butylaldehyde and may contain, for example, no more than 50 weight percent, no more than 40 weight percent, no more than 30 weight percent, no more than 20 weight percent, no more than 10 weight percent, no more than 5 weight percent, or no more than 2 weight percent of residues of aldehydes other than n-butylaldehyde, based on the total weight of all aldehyde residues of the resin.

[0036] When the polyvinyl acetal resin present in one or more layers comprises a PVB resin, the molecular weight of the resin, measured as described above, can be at least 30,000, at least 50,000, at least 70,000, at least 100,000, at least 250,000, or at least 500,000 daltons, and / or no more than 1,000,000 daltons, 750,000 daltons, 600,000 daltons, 550,000 daltons, 500,000 daltons, 450,000 daltons, or 425,000 daltons. The molecular weight of the polyvinyl acetal resin can range from 50,000 to 1,000,000, 100,000 to 750,000, or 250,000 to 750,000 daltons.

[0037] The at least one polyvinyl acetal resin present in one or more layers of the intermediate layer (e.g., the first and third layers 1, 3 shown in FIG. 2) can have a residual hydroxyl content of 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, or at least 20.5 weight percent, and / or no more than 30 weight percent, no more than 29 weight percent, no more than 28 weight percent, no more than 27 weight percent, no more than 26 weight percent, no more than 25 weight percent, no more than 24 weight percent, no more than 23 weight percent, no more than 22 weight percent, no more than 21 weight percent, no more than 20 weight percent, or no more than 19.5 weight percent.

[0038] Additionally or alternatively, the at least one polyvinyl acetal resin present in one or more layers (e.g., first and third layers 1, 3 shown in FIG. 2) can have a residual acetate content of at least 0.5, at least 1, at least 1.5, at least 2, at least 5, at least 10, at least 15, or at least 18 weight percent and / or no more than 35 weight percent, no more than 30 weight percent, no more than 25 weight percent, no more than 20 weight percent, no more than 15 weight percent, no more than 10 weight percent, no more than 8 weight percent, no more than 6 weight percent, no more than 5 weight percent, no more than 3 weight percent, no more than 2.5 weight percent, or no more than 2 weight percent.

[0039] In some cases, one or more of the polyvinyl acetal resins (including modified polyvinyl acetal resins) may contain less than 5 weight percent, less than 3 weight percent, less than 2 weight percent, less than 1 weight percent, less than 0.5 weight percent, less than 0.1 weight percent, or less than 0.05 weight percent of residual hydroxyl, residual acetal, and residues other than aldehyde (e.g., olefinic, acrylic, butadiene, imide, etc.) In some cases, at least one polyvinyl acetal resin may contain less than 5 weight percent, less than 4 weight percent, less than 3 weight percent, less than 2 weight percent, less than 1 weight percent, or less than 0.5 weight percent of residues of any cyclic vinyl monomer described herein.

[0040] According to some embodiments, two or more layers of a multi-layer intermediate layer may have different compositions. For example, in some embodiments, one or both outer skin layers may be formed from at least a first polyvinyl acetal resin or resin component (e.g., an unmodified polyvinyl acetal resin), and the core or inner layer may be formed from at least a second polyvinyl acetal resin or resin component (e.g., a modified polyvinyl acetal resin or component). In some embodiments, the at least one polyvinyl acetal resin used to form the first layer may have a residual hydroxyl content and / or residual acetate content that is at least 2, at least 3, at least 4, at least 5, at least 6, or at least 8 weight percent higher or lower than the residual hydroxyl content and / or residual acetate content of the at least one second polyvinyl acetal resin used to form the second layer.

[0041] In some cases, the difference in the residual hydroxyl content of the polyvinyl acetal resins of two or more of the layers (e.g., the first and second and / or the second and third) can also be at least 2, at least 5, at least 10, at least 12, at least 15, at least 20, or at least 30 weight percent, and / or no more than 30 weight percent, 25 weight percent, 20 weight percent, 15 weight percent, 10 weight percent, or 8 weight percent. As used herein, the term "different weight percent" or "difference is at least... weight percent" refers to the difference between two given weight percents, calculated by subtracting one number from the other. For example, a polyvinyl acetal resin with a residual hydroxyl content of 12 weight percent has a residual hydroxyl content that is 2 weight percent less than a polyvinyl acetal resin with a residual hydroxyl content of 14 weight percent (14 weight percent - 12 weight percent = 2 weight percent). As used herein, the term "different" can refer to a value that is higher or lower than another value.

[0042] In some embodiments, at least one of the polyvinyl acetal resins used to form two different layers, for example, within an intermediate layer, can have a different residual acetate content than the other. For example, in some embodiments, the difference (or maximum difference) in the residual acetate content of two of the polyvinyl acetal resins (or any of the layers of the intermediate layer) can be at least 2, at least 3, at least 4, at least 5, at least 8, or at least 10 percent by weight, and / or 15 percent or less, 13 percent or less, 10 percent or less, 8 percent or less, 6 percent or less, 4 percent or less, 2 percent or less, 1 percent or less, or 0.5 percent or less. One of the polyvinyl acetal resins can have a residual acetate content, measured as described above, of less than 15 percent by weight, 13 percent or less, 12 percent or less, 10 percent or less, 8 percent or less, 6 percent or less, 5 percent or less, 4 percent or less, 3 percent or less, 2 percent or less, 1 percent or less, or 0.5 percent or less.

[0043] In some embodiments, at least one of the polyvinyl acetal resins used to form the layers of the intermediate layer may have a residual acetate content of at least 5, at least 8, at least 10, at least 12, at least 14, at least 16, at least 18, at least 20, or at least 30 weight percent. The difference in residual acetate content between the polyvinyl acetal resins used in two or more resin layers may be within the above ranges, or the difference may be less than 3 weight percent, 2 weight percent or less, 1 weight percent or less, or 0.5 weight percent or less.

[0044] In some embodiments, the difference in residual acetate content of polyvinyl acetal resins used in two or more layers can be less than 2 weight percent, 1 weight percent or less, 0.5 weight percent or less, and the difference in residual acetate content between polyvinyl acetal resins used in two or more layers can be at least 3, at least 5, at least 8, at least 15, at least 20, or at least 30 weight percent. In other embodiments, the difference in residual acetate content of polyvinyl acetal resins used in two or more layers can be less than 3 weight percent, 2 weight percent or less, 1 weight percent or less, or 0.5 weight percent or less, and the difference in residual hydroxyl content of the polyvinyl acetal resins can be at least 2, at least 5, at least 10, at least 12, at least 15, at least 20, or at least 30 weight percent.

[0045] In some embodiments, one or more of the layers may include at least one plasticizer. In some cases, each of the resin layers shown in Figure 2 may include a polyvinyl acetal resin and at least one plasticizer. Depending on the specific composition of the layer, the one or more plasticizers may be present in an amount of at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, or at least 70 phr (parts per hundred parts resin), and / or no more than 120 phr, no more than 110 phr, no more than 105 phr, no more than 100 phr, no more than 95 phr, no more than 90 phr, no more than 85 phr, no more than 80 phr, no more than 75 phr, no more than 70 phr, no more than 65 phr, no more than 60 phr, no more than 55 phr, no more than 50 phr, no more than 45 phr, no more than 40 phr, or no more than 35 phr, or in a range of 5 to 120, 10 to 110, 20 to 90, or 25 to 75 phr. These amounts may refer to a single plasticizer, a blend of plasticizers, or one plasticizer in a blend of two or more plasticizers.

[0046] As used herein, the term "parts per hundred parts of resin" or "phr" refers to the amount of plasticizer present relative to 100 parts of resin, on a weight basis. For example, if 30 grams of plasticizer is added to 100 grams of resin, the plasticizer is present in an amount of 30 phr. If a layer includes more than one resin, the weight of the plasticizer is compared to the total amount of all resins present to determine the parts per hundred of resin. Additionally, when the plasticizer content of a layer is given, it is given with reference to the amount of plasticizer in the mixture or melt used to make the layer.

[0047] Examples of suitable plasticizers include, but are not limited to, triethylene glycol di(2-ethylhexanoate) (“3GEH”), triethylene glycol di(2-ethylbutyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, tetraethylene glycol di(2-ethylhexanoate) (“4GEH”), dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, di(butoxyethyl) adipate, and bis(2-(2-butoxyethoxy)ethyl) adipate, dibutyl sebacate, dioctyl sebacate, and mixtures thereof. The plasticizer may be selected from the group consisting of triethylene glycol di(2-ethylhexanoate) and tetraethylene glycol di(2-ethylhexanoate), or the plasticizer may include triethylene glycol di(2-ethylhexanoate).

[0048] Additionally or alternatively, the plasticizer may include one or more of the following plasticizers: dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, butoxyethyl benzoate, butoxyethoxyethyl benzoate, butoxyethoxyethoxyethyl benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, 2,2,4-trimethyl 1,3-pentanediol benzoic acid 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, bisphenol A bis(2-ethylhexanoate), di-(butoxyethyl) terephthalate, di(butoxyethoxyethyl) terephthalate, and mixtures thereof.

[0049] In some embodiments, at least one layer (e.g., outer layers 1, 3 in Figure 2) may include at least one plasticizer in an amount of at least 20, at least 25, at least 30, or at least 35 phr, and / or no more than 45 phr, no more than 40 phr, or no more than 35 phr. Additionally or alternatively, at least one other layer (e.g., core layer 2 in Figure 2) may include at least one plasticizer in an amount of at least 50, at least 55, at least 60, at least 65, or at least 70 phr, and / or no more than 95 phr, no more than 90 phr, no more than 85 phr, no more than 80 phr, or no more than 75 phr.

[0050] At least one of the plasticizers used in the layers or interlayers may have a refractive index of at least 1.435, at least 1.440, at least 1.445, at least 1.450, at least 1.460, at least 1.470, at least 1.475, at least 1.480, at least 1.490, or at least 1.500, and / or 1.530 or less, 1.525 or less, 1.520 or less, 1.515 or less, 1.510 or less, 1.505 or less, 1.500 or less, 1.495 or less, 1.490 or less, or 1.485 or less.

[0051] In some cases, at least one resin layer (e.g., core layer 2 shown in FIG. 2) may have a total plasticizer content in the range of 20 to 120 phr, 30 to 90 phr, 45 to 85 phr, or 55 to 80 phr. Alternatively, or in addition, at least one resin layer (e.g., outer layers 1 and 3 shown in FIG. 2) may have a total plasticizer content in the range of 20 to 45 phr or 30 to 40 phr. The plasticizer content refers to the total amount of plasticizer in the intermediate layer and may be the amount of one or more plasticizers contained in the intermediate layer.

[0052] Resins with higher or lower residual hydroxyl and / or acetate contents may also ultimately contain different amounts of plasticizer when combined with at least one plasticizer. As a result, layers formed from polyvinyl acetal resins with different compositions may also have different properties within a single interlayer. Without wishing to be bound by theory, it is believed that the compatibility of a given plasticizer with a polyvinyl acetal resin may depend, at least in part, on the polymer's composition, particularly its residual hydroxyl content. Overall, polyvinyl acetal resins with higher residual hydroxyl contents tend to exhibit lower compatibility (or capacity) with a given plasticizer compared to similar resins with lower residual hydroxyl contents. As a result, polyvinyl acetal resins with higher residual hydroxyl contents tend to be less plasticizable and exhibit higher stiffness than similar resins with lower residual hydroxyl contents. Conversely, polyvinyl acetal resins with low residual hydroxyl content, when plasticized with a given plasticizer, tend to incorporate higher amounts of plasticizer, which may result in a softer resin layer exhibiting a lower glass transition temperature than a similar resin with a higher residual hydroxyl content. Depending on the particular resin and plasticizer, these trends may be reversed.

[0053] The types of plasticizers used in the skin and core layers can be the same or different. In some embodiments, at least one plasticizer can be a blend of two or more plasticizers. Furthermore, in some embodiments, two outer skin layers (e.g., outer layers 1 and 3 shown in FIG. 2) can have approximately the same or identical compositions (including type and / or amount of plasticizer) as each other, while the core layer can contain a different amount of plasticizer.

[0054] In some embodiments, the difference in plasticizer content between two or more resin layers can be at least 2, at least 5, at least 8, at least 10, at least 12, or at least 15, at least 20, at least 25, at least 30, or at least 35 phr. In some cases, a resin layer containing a resin with a lower hydroxyl content can have a higher plasticizer content. To control or maintain other properties of the resin layer or interlayer, the difference in plasticizer content between two of the layers can be 75 phr or less, 70 phr or less, 65 phr or less, 60 phr or less, 55 phr or less, 50 phr or less, 45 phr or less, 40 phr or less, 30 phr or less, 25 phr or less, 20 phr or less, or 17 phr or less. In other embodiments, the difference in plasticizer content between two of the resin layers can be at least 25 phr, at least 30 phr, at least 35 phr, at least 40 phr, at least 50 phr, at least 60 phr, at least 70 phr, or at least 80 phr. In some embodiments, the outer skin layers (eg, first and third layers 1, 3) can have a lower plasticizer content than the plasticizer content of the inner core layer (eg, second layer 2).

[0055] Glass transition temperature, or Tg, is the temperature that characterizes the transition of a polymer from a glassy state to a rubbery state. At least one of the plasticized resin layers (e.g., core layer 2) may have a glass transition temperature above -15°C, above -12°C, above -10°C, above -5°C, above -2°C, or above 0°C, and / or below 20°C, 15°C, 12°C, 10°C, 5°C, 2°C, 0°C, or below -1°C. Alternatively, or in addition, at least one of the resin layers (e.g., at least one skin layer 1 or 3 shown in Figure 2) may have a glass transition temperature of at least 20, at least 22, at least 25, at least 27, at least 29, or at least 30°C, and / or below 55°C, 50°C, 45°C, 40°C, 35°C, or 32°C.

[0056] The glass transition temperatures of the layers described herein were determined by dynamic mechanical thermal analysis (DMTA). DMTA measures a specimen's storage (elastic) modulus in Pascals (G'), loss (viscous) modulus in Pascals (G"), and tan delta (G" / G') as a function of temperature at a given oscillation frequency and temperature sweep rate. The glass transition temperature is then determined by the location of the tan delta peak on the temperature scale. The glass transition temperatures provided herein were determined in shear mode at an oscillation frequency of 1 Hz and a temperature sweep rate of 3°C / min.

[0057] In some embodiments, two of the resin layers may have different glass transition temperatures, particularly when two of the resin layers have resins with different hydroxyl or acetate and / or plasticizer content. The difference in glass transition temperatures of two of the layers (such as, for example, one of outer layers 1, 3 and core layer 2 shown in FIG. 2) may be at least 2, at least 3, at least 5, at least 8, at least 10, at least 12, at least 15, at least 18, at least 20, at least 22, at least 25, at least 30, or at least 35° C., and / or no more than 60° C., 55° C., 50° C., 45° C., 40° C., 35° C., 30° C., or 25° C.

[0058] In some cases, the outer layer(s) of a multilayer intermediate layer may have a higher Tg and thus be considered the "hard" outer layer, while the inner layer of the multilayer intermediate layer has a lower Tg and may be considered the "soft" intermediate layer. In some embodiments, the outer skin layer(s) may have a Tg that is at least 2, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, or at least 35°C higher than the Tg of the inner core layer, and / or 100°C or lower, 90°C or lower, 75°C or lower, 70°C or lower, 65°C or lower, 60°C or lower, 55°C or lower, 50°C or lower, 45°C or lower, or 40°C or lower, 35°C or lower, 30°C or lower, 25°C or lower.

[0059] With respect to optical properties, one or more of the plasticized resin layers may have a refractive index of at least 1.465, at least 1.470, at least 1.472, at least 1.474, at least 1.475, at least 1.480, at least 1.485, at least 1.490, at least 1.495, at least 1.500, at least 1.505, at least 1.510, at least 1.525, and / or 1.600 or less, 1.590 or less, 1.580 or less, 1.570 or less, 1.560 or less, 1.550 or less, 1.540 or less, 1.530 or less, 1.520 or less, 1.510 or less, 1.500 or less, 1.490 or less, 1.482 or less, 1.480 or less, or 1.479 or less.

[0060] The two or more layers of the intermediate layer may have different refractive indices based on the specific composition of each layer, including the type and amount of plasticizer and the specific polyvinyl acetal resin present in each layer. In some cases, the difference in refractive index between two of the layers of the intermediate layer (e.g., the skin and core layers) may be at least 0.0001, at least 0.005, at least 0.0010, and / or no more than 0.0100, 0.0075, 0.0050, or 0.0025, even when one layer (e.g., core layer 2) contains a modified polyvinyl acetal resin and another layer (e.g., one or more skin layers 1, 3) contains an unmodified polyvinyl acetal resin or no modified polyvinyl acetal resin.

[0061] In some cases, at least one layer (e.g., the first and / or third resin layers 1, 3) may have a refractive index of at least 1.470, at least 1.472, at least 1.474, and / or 1.482 or less, 1.480 or less, or 1.479 or less, and at least one of the other layers (e.g., the second resin layer 2) may have a refractive index of at least 1.465, at least 1.470, at least 1.475, at least 1.480, or at least The refractive index may be 1.485, at least 1.490, at least 1.495, at least 1.500, at least 1.505, at least 1.510, or at least 1.525, and / or 1.600 or less, 1.590 or less, 1.580 or less, 1.570 or less, 1.560 or less, 1.550 or less, 1.540 or less, 1.530 or less, 1.520 or less, 1.510 or less, 1.500 or less, or 1.490 or less.

[0062] In some embodiments, the entire intermediate layer can have a refractive index of at least 1.480, at least 1.482, at least 1.485, at least 1.487, at least 1.490, at least 1.500, at least 1.510, at least 1.520, at least 1.525, and / or 1.700 or less, 1.675 or less, 1.650 or less, 1.625 or less, 1.600 or less, 1.575 or less, 1.550 or less, 1.525 or less, 1.500 or less, 1.495 or less, 1.490 or less, or 1.485 or less.

[0063] Additionally, one or more of the layers of a multi-layer interlayer may contain at least one additive that can impart specific properties or characteristics to the polymer layer or interlayer. Such additives include, but are not limited to, dyes, pigments, stabilizers such as UV stabilizers, antioxidants, antiblocking agents, flame retardants, IR absorbers or blockers, such as indium tin oxide, antimony tin oxide, lanthanum hexaboride (LaB6), and cesium tungsten oxide, processing aids, flow promoters, lubricants, impact modifiers, nucleating agents, heat stabilizers, UV absorbers, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcing additives, fillers, and adhesion control agents (ACAs). The specific type and amount of such additives may be selected based on the final properties or end use of a particular interlayer, and may be used to the extent that the additive or additives do not adversely affect the final properties of the interlayer or windshield utilizing the interlayer for a particular application.

[0064] In some cases, one or more resin layers (or the entire interlayer) may be free of solid refractive index (RI) additives. As used herein, the term "solid RI additive" refers to an additive used to adjust the refractive index of a poly(vinyl acetal) resin, resin layer, or interlayer, which is solid at ambient conditions of 25°C and 1 atm. One or more or all of the resin layers within the interlayer may contain less than 0.5 phr, less than 0.25 phr, or less than 0.10 phr. Examples of solid RI additives include, but are not limited to, polyadipates, polystyrenes with molecular weights less than 2500, epoxides, phthalates, benzoates, inorganic oxides such as zirconium oxide, halogenated additives, and silicon-containing additives, as well as combinations thereof.

[0065] In some embodiments, one or both of the outer skin layers may include a gradient color band near one or both edges of the intermediate layer. Such gradient color bands may be embedded in all or part of the outer skin layer or layers of the intermediate layer and may have a thickness of 0.025 to 0.375 mm, 0.125 to 0.325 mm, or 0.225 to 0.300 mm. The thickness of one outer skin layer on each side of the intermediate layer may be 0.0125 to 0.075 mm, 0.025 to 0.05 mm, or 0.03 to 0.04 mm. As used herein, the term "outer skin layer" includes gradient color bands, if present.

[0066] According to some embodiments, at least one of the surfaces of the layers or interlayers may be textured to facilitate the formation of the interlayer or glazing. For example, at least a portion of at least one of the surfaces of one or more of the layers or interlayers may have a surface roughness (Rz) of at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, or at least 50 microns, and / or no more than 150 microns, no more than 140 microns, no more than 130 microns, no more than 120 microns, no more than 110 microns, no more than 100 microns, no more than 90 microns, no more than 80 microns, no more than 75 microns, no more than 70 microns, no more than 65 microns, no more than 60 microns, or no more than 40 microns.

[0067] As used herein, Rz is a measure of the surface topography of a polymer layer and is an indicator of the deviation of the surface from flatness. Furthermore, the surface roughness of a layer can also be described by its Rsm, which is a measure of the distance between peaks in the topography of the surface of the polymer layer. Further information regarding methods for determining Rz and Rsm is provided in U.S. Pat. No. 7,883,761, the entire contents of which are incorporated herein by reference to the extent consistent with the present disclosure. Such roughness can be achieved by any suitable method, including, but not limited to, embossing, melt-fracturing, and combinations thereof.

[0068] The intermediate layer can have any suitably shaped profile, including, for example, a flat profile having a generally uniform thickness, or a wedge-shaped profile having a constant or variable change in thickness. When the intermediate layer has a flat profile, at least 90, at least 92, at least 95, at least 97, at least 99, or all of the layer or vertical cross sections of the intermediate layer have a uniform thickness. Such intermediate layers may also be non-wedge-shaped and have a wedge angle of about zero or less than 0.05 milliradians (mrad).

[0069] When an interlayer has a constant thickness profile (as generally shown in FIG. 2 ), each of its individual layers can be flat, or two or more can have wedge-shaped profiles and be arranged so that the overall profile of the interlayer is flat (embodiment not shown). The overall thickness of an interlayer with a constant thickness profile can be at least 25, at least 27, or at least 30 mils, and / or no more than 37 mils, 35 mils, or 34 mils. Each layer can have an average thickness of at least 1, at least 2, at least 3, at least 5, or at least 6 mils, and / or no more than 20 mils, 15 mils, 10 mils, 8 mils, or 6 mils, with the core layer having a thickness of 1 to 8 mils or 2 to 6 mils, and the skin layers having a thickness of 1 to 15 mils or 2 to 12 mils, respectively. As used herein, the term “average thickness” refers to the thickness of a layer or interlayer measured at 10 equally spaced locations across the entire vertical height of the interlayer and then averaged (i.e., divided by 10).

[0070] In some cases, the resin used to form the skin layer may comprise 50 to 95 weight percent or 85 to 92 weight percent of the total intermediate layer, and the resin used to form the core layer may comprise 5 to 50 or 8 to 15 weight percent of the total intermediate layer.

[0071] In some embodiments, the intermediate layer can have an overall wedge-like or wedge-shaped profile. As used herein, the term "wedge-shaped" or "wedge-like" means having a cross-sectional shape in which at least a portion increases from a relatively thin dimension to a relatively thick dimension. In some cases, the thickness of the thinnest edge of the wedge-shaped portion of the intermediate layer (e.g., tapered zone) can be at least 0.50, at least 0.55, at least 0.60, at least 0.65, or at least 0.70 mm, and / or 1.1 mm or less, 1.0 mm or less, 0.95 mm or less, 0.90 mm or less, 0.85 mm or less, 0.80 mm or less, 0.75 mm or less, or 0.70 mm or less, and the thickness of the thinnest edge of the wedge-shaped portion of the intermediate layer (e.g., tapered zone) can be at least 0.50, at least 0.55, at least 0.60, at least 0.65, or at least 0.70 mm. The thickness of the thick edge can be at least 0.60, at least 0.65, at least 0.70, at least 0.75, at least 0.80, at least 0.85, or at least 0.90 mm, and / or no more than 2.0 mm, no more than 1.95 mm, no more than 1.90 mm, no more than 1.85 mm, no more than 1.80 mm, no more than 1.75 mm, no more than 1.70 mm, no more than 1.65 mm, no more than 1.60 mm, no more than 1.55 mm, or no more than 1.50 mm. The thickness of an entire intermediate layer at any point is the combined thickness of all of its layers at that point.

[0072] If at least one layer of the intermediate layers (or the intermediate layers themselves) is wedge-shaped, at least a portion of the intermediate layers may have at least one wedge angle of at least 0.05, at least 0.10, at least 0.13, at least 0.15, at least 0.20, at least 0.25, at least 0.30, at least 0.35, or at least 0.40 milliradians (mrad), and / or 1.0 mrad or less, 0.90 mrad or less, 0.85 mrad or less, 0.80 mrad or less, 0.75 mrad or less, 0.70 mrad or less, 0.65 mrad or less, or 0.60 mrad or less. In some embodiments, the intermediate layer may have an overall wedge angle of at least 0.3, at least 0.35, at least 0.40, at least 0.45, at least 0.50, at least 0.55, at least 0.60, at least 0.65, at least 0.70, at least 0.75 mrad, and / or 0.80 mrad or less, 0.75 mrad or less, 0.70 mrad or less, 0.65 mrad or less, 0.60 mrad or less, 0.55 mrad or less, 0.50 mrad or less, 0.45 mrad or less, 0.40 mrad or less, 0.35 mrad or less, 0.30 mrad or less.

[0073] In some embodiments, when the intermediate layer is a multi-layer intermediate layer, one or more of the skin layers or core layers may be wedge-shaped. In some cases, only the outer skin layer may be wedge-shaped, and the inner core layer may be flat or substantially flat. In other cases, one of the skin layers may be wedge-shaped and the other may be flat. In some cases, both the outermost skin layer and the innermost core layer may be wedge-shaped, with similar or different wedge angles. In other cases, the outer layer may be flat, and the inner core layer is wedge-shaped. In other cases, the outer skin layer may be wedge-shaped, and the inner core layer may be wedge-shaped or flat.

[0074] If the interlayer is a wedge-shaped interlayer, it may have at least one constant wedge angle that does not vary across all or a portion of the interlayer, while in other cases the wedge angle may vary continuously across all or a portion of the region of non-uniform thickness. Particular embodiments of interlayers having different tapered zone configurations are described in detail in U.S. Patent Application Publication No. 2017 / 0285339, the entirety of which is incorporated herein by reference to the extent not inconsistent with the present disclosure.

[0075] Whether the intermediate layer has a flat or wedge-shaped profile, the outer skin layers (shown as layers 1 and 3 in FIG. 2) can have similar or different thicknesses. If the outer layers have similar thicknesses, the maximum difference in thickness between the two outer layers can be 5 percent or less, 3 percent or less, 2 percent or less, 1 percent or less, or 0.5 percent or less. In some cases, the two outer skin layers can have the same nominal thickness.

[0076] In other embodiments, at least a portion of one outer skin layer 1 or 3 can be thicker than at least a portion of the other outer skin layer 3 or 1. For example, in some embodiments, one of the outer skin layers 1, 3 can be at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, or at least 50 percent thicker than the other outer skin layer at one or more locations along the intermediate layer. Alternatively, or in addition, at least a portion of one outer skin layer 1 or 3 can be no more than 90 percent, no more than 85 percent, no more than 80 percent, no more than 75 percent, no more than 70 percent, no more than 65 percent, no more than 60 percent, no more than 55 percent, no more than 50 percent, or no more than 45 percent thicker than the other outer skin layer 3 or 1 at one or more locations along the intermediate layer.

[0077] The interlayers described herein can be formed by any suitable method. For example, in some embodiments, a multilayer interlayer can be formed by coextrusion. In such a process, at least three resin streams, including a first outer skin resin stream, a second outer skin resin stream, and an inner core resin stream located between the first and second outer skin resin streams, are simultaneously extruded through a die to form a coextruded resin sheet. In other embodiments, a multilayer interlayer can be formed by separately extruding the first outer skin, second outer skin, and core resin streams to form three separate layers, and then laminating these layers together to form the multilayer interlayer. In some cases, both coextrusion and lamination can be used to form a multilayer interlayer. In some cases, coextrusion can be used to form a multilayer sheet having, for example, at least two, at least three, or four or more layers. The sheet can then be laminated to another sheet containing one or more other layers to form the multilayer interlayer. In some cases, one or more layers of the sheet can be flat, and one or more layers of the sheet can be wedge-shaped. In some embodiments, the multi-layer sheet may have a flat profile and may be laminated to a single layer sheet having a wedge-shaped profile to provide a wedge-shaped multi-layer interlayer.

[0078] Interlayers constructed and formed according to embodiments of the present technology may exhibit enhanced optical and / or acoustic properties compared to interlayers formed from conventional polymer layers. For example, in some embodiments, the interlayer may have a mottle value of 3.5 or less, 3.25 or less, 3 or less, 2.75 or less, 2.5 or less, 2.25 or less, 2 or less, 1.75 or less, 1.5 or less, or 1 or less. Mottle is a measure of optical quality and is detected as texture or graininess. Too much or too intense mottle can result in an undesirable visual appearance for the interlayer or glazing.

[0079] The mottle values ​​provided herein were determined using a Clear Mottle Analyzer (CMA), which includes a xenon arc lamp, a sample holder, a projection screen, and a digital camera. The xenon arc lamp is used to project a shadowgraph of the laminated sample onto the screen, and the camera is configured to capture an image of the resulting shadowgraph. The image is then digitally analyzed using computer imaging software and compared to a previously acquired image of a standard sample to determine the mottle of the sample. The method for measuring mottle using a CMA is described in detail in U.S. Pat. No. 9,311,699.

[0080] Transparency is another optical parameter used to describe the performance of the interlayers described herein and can be determined by measuring the haze value or percentage. Haze represents a quantification of the light scattered by a sample relative to incident light. In some embodiments, the resin blends, layers, and interlayers described herein can have a haze value of less than 5 percent, less than 4 percent, less than 3 percent, less than 2 percent, less than 1 percent, or less than 0.5 percent, measured at a 2-degree observer angle using Illuminant C according to ASTM D1003-13-Procedure B. Testing is performed on a 0.76 mm thick polymer sample laminated between two sheets of clear glass (commercially available from Pittsburgh Glass Works, Pennsylvania), each 2.3 mm thick, using a spectrophotometer such as a Hunterlab UltraScan XE instrument (commercially available from Hunter Associates, Reston, Va.).

[0081] In some embodiments, the interlayer may have a visible transmittance (%TvisK) of at least 65, at least 70, at least 75, at least 80, at least 81, at least 82, at least 83, at least 84, at least 85, at least 85.5, at least 86, at least 86.5, at least 87, at least 87.5, at least 88, or at least 88.5 percent. Additionally or alternatively, the interlayer may have a total solar transmittance (%Tts) of 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, or 45% or less, measured according to ISO 13837.

[0082] The interlayers described herein may also exhibit desirable acoustic performance. For example, in some embodiments, interlayers according to embodiments of the present technology may have a tan delta value of at least 0.70. Tan delta is the ratio of the loss modulus (G") in Pascals to the storage modulus (G') in Pascals of a sample as measured by dynamic mechanical thermal analysis (DMTA). DMTA is performed in shear mode at an oscillation frequency of 1 Hz and a temperature sweep rate of 3°C / min. The peak value of the G" / G' curve at the glass transition temperature is the tan delta value. The tan delta of interlayers described herein may be at least 1.0, at least 1.05, at least 1.10, at least 1.25, at least 1.50, at least 1.75, at least 2.0, or at least 2.25, and / or 5 or less, 4.75 or less, 4.5 or less, 4.25 or less, 4 or less, 3.75 or less, 3.5 or less, 3.25 or less, 3 or less, or 2.5 or less.

[0083] Additionally, the interlayer may have a damping loss factor or loss factor of at least 0.10, at least 0.15, at least 0.17, at least 0.20, at least 0.25, at least 0.27, at least 0.30, at least 0.33, or at least 0.35. The loss factor is measured by Mechanical Impedance Measurement as described in ISO Standard 16940. A polymer sample is laminated between two sheets of clear glass, each 2.3 mm thick, and prepared to have a width of 25 mm and a length of 300 mm. The laminated sample is then excited at its center point using a vibration shaker commercially available from Bruel and Kjaer (Naerum, Netherlands), and an impedance head (Bruel and Kjaer) is used to measure the force required to excite the bar into vibration and the velocity of vibration. The resulting transfer function is recorded using a National Instrument data acquisition and analysis system, and the loss factor for the first vibration mode is calculated using the half-power method.

[0084] According to embodiments of the present technology, an interlayer having at least one resin layer comprising a modified polyvinyl acetal resin described herein may be more easily recycled and / or recycled in greater quantities than a similar interlayer that does not comprise a modified polyvinyl acetal. For example, in some cases, a multi-layer interlayer that includes at least one pair of outer skin layers and an inner core layer that comprises a modified polyvinyl acetal resin may be more easily recycled than a similar multi-layer interlayer that does not have the same skin layers and core layer that does not comprise a modified polyvinyl acetal resin.

[0085] Recycling of the interlayer can be carried out by any known process, and in some cases results in a blend of two or more polyvinyl acetal resins (e.g., skin resin and core resin), usually containing at least one plasticizer. In some cases, because the refractive index of the modified polyvinyl acetal resin is increased compared to a similar unmodified polyvinyl acetal resin, a greater amount of the modified polyvinyl acetal resin can be recycled than would be expected if the resin were unmodified, and the recycled composition can still maintain desirable properties, including optical properties. The recycled interlayer can include post-consumer scrap, post-industrial scrap, and / or pre-consumer scrap.

[0086] For example, in some cases, a recycled blend composition may include at least one polyvinyl acetal resin and at least one modified polyvinyl acetal resin as described herein. The two resins may have different hydroxyl contents within one or more of the ranges herein, resulting in different plasticizer contents and / or refractive indices. The modified polyvinyl acetal resin may be present in the blend composition in an amount of at least 1.2, at least 1.5, at least 2, at least 5, at least 10, at least 12, or at least 15 weight percent, and / or no more than 30 weight percent, no more than 25 weight percent, no more than 20 weight percent, no more than 17 weight percent, no more than 15 weight percent, or no more than 10 weight percent, based on the total weight of the resins in the composition.

[0087] In some cases, the total amount of modified polyvinyl acetal resin compositions (e.g., plasticized polyvinyl acetal resins described herein) can be present in the blend composition in an amount of at least 1, at least 2, at least 5, at least 10, at least 12, or at least 15 weight percent, and / or no more than 50 weight percent, no more than 45 weight percent, no more than 40 weight percent, no more than 35 weight percent, no more than 30 weight percent, no more than 25 weight percent, no more than 20 weight percent, or no more than 15 weight percent, based on the total weight of the blend composition (e.g., resin and plasticizer). Even with higher amounts of different polyvinyl acetal resins, the blend composition can exhibit a haze of less than 2, less than 1.5, or less than 1.

[0088] In some cases, at least a portion of the blend composition can be used to form a recycled content interlayer. Such an interlayer can include, for example, at least 1, at least 5, at least 10, at least 15, at least 20, or at least 25 percent, and / or up to 75 percent, 70 percent, 65 percent, 60 percent, 55 percent, 50 percent, or 45 percent recycled content material, based on the total weight of the interlayer. In some cases, at least a portion of the outer skin layer of the recycled content interlayer can include recycled content resin (e.g., including recycled content-modified PVB resin) and at least one plasticizer and can have one or more of the properties discussed herein. The interlayer can be a multi-layer interlayer, with other layers either containing recycled content resin or not.

[0089] The interlayers described herein can be used to form glazing (or laminates or panels) by sandwiching an interlayer according to embodiments of the present technology between a first rigid substrate and a second rigid substrate and laminating the structure to form multi-layer glazing.

[0090] The multilayer glazing or panels described herein generally include a first rigid substrate sheet having a first substrate thickness and a second rigid substrate sheet having a second substrate thickness. Each of the first and second substrates can be formed from a rigid material, such as glass, and can be formed from the same or different materials. In some embodiments, at least one of the first and second substrates can be a glass substrate. In other embodiments, at least one of the first and second substrates can be formed from another material, including, for example, a rigid polymer, such as polycarbonate, copolyester, acrylic, polyethylene terephthalate, and combinations thereof. In embodiments, both rigid substrates are glass. Any suitable type of non-glass material may be used to form such substrates, depending on the performance and properties desired.

[0091] Any suitable type of glass may be used to form the rigid glass substrate; in some embodiments, the glass may be selected from the group consisting of aluminosilicate glass, borosilicate glass, quartz glass or fused silica glass, and soda-lime glass. When used, the glass substrate may be annealed, heat-strengthened, or tempered, chemically tempered, etched, coated, or strengthened by ion exchange, or may have been subjected to one or more of these treatments. The glass itself may be rolled glass, float glass, or flat glass. In some embodiments, the glass may not be chemically treated or strengthened by ion exchange, while in other embodiments, the glass may not be aluminosilicate glass. When the first and second substrates are glass substrates, the types of glass used to form each substrate may be the same or different.

[0092] The rigid substrates can have any suitable thickness. In some embodiments, when the rigid substrates are all glass substrates, the nominal thickness of at least one of the glass sheets (first or second glass) ranges from 0.1 mm to 12.7 mm, and the multi-layer glass panel includes any combination of the first and second glass sheets (and any other glass or rigid sheets, as appropriate). In some embodiments, the nominal thickness of the first and / or second substrate can be at least 0.4 mm, at least 0.5 mm, at least 0.7 mm, at least 0.75 mm, at least 1.0 mm, at least 1.25 mm, at least 1.3 mm, at least 1.6 mm, at least 1.9 mm, at least 2.2 mm, at least 2.5 mm, or at least 2.8 mm, and / or less than 3.2 mm, less than 2.9 mm, less than 2.6 mm, less than 2.5 mm, less than 2.3 mm, less than 2.0 mm, less than 1.75 mm, less than 1.7 mm, less than 1.5 mm, less than 1.4 mm, or less than 1.1 mm.

[0093] Additionally or alternatively, the first and / or second substrate may have a nominal thickness of at least 2.3 mm, at least 2.6 mm, at least 2.9 mm, at least 3.2 mm, at least 3.5 mm, at least 3.8 mm, or at least 4.1 mm, and / or less than 12.7 mm, less than 12.0 mm, less than 11.5 mm, less than 10.5 mm, less than 10.0 mm, less than 9.5 mm, less than 9.0 mm, less than 8.5 mm, less than 8.0 mm, less than 7.5 mm, less than 7.0 mm, less than 6.5 mm, less than 6.0 mm, less than 5.5 mm, less than 5.0 mm, or less than 4.5 mm. Other thicknesses may be appropriate depending on the application and desired properties.

[0094] When a multilayer panel includes two substrates having the same nominal thickness, the panel may be referred to as a "symmetrical configuration" because the ratio of the nominal thickness of one substrate to the nominal thickness of the other substrate is equal to 1. When a multilayer panel includes two substrates having different nominal thicknesses, the panel may be referred to as an "asymmetrical configuration" because the ratio of the nominal thickness of one substrate to the nominal thickness of the other substrate is not equal to 1. In some cases, the thicker rigid substrate or panel may have a nominal thickness that is at least 1.05, at least 1.5, at least 2, at least 2.5, at least 3, or at least 5 times thicker than the nominal thickness of the thinner rigid substrate or panel, and / or no more than 10 times, no more than 8 times, no more than 6 times, no more than 5 times, no more than 3 times, no more than 2 times, or no more than 1.5 times thicker.

[0095] In some embodiments, one or both of the substrates may be wedge-shaped. When one or both of the rigid substrates is a wedge-shaped substrate, the substrates may define a wedge angle of at least 0.05, at least 0.10, at least 0.15, at least 0.20, at least 0.25, at least 0.30, or at least 0.35 milliradians, and / or 1 milliradian or less, 0.95 milliradians or less, 0.90 milliradians or less, 0.85 milliradians or less, 0.80 milliradians or less, 0.75 milliradians or less, 0.70 milliradians or less, 0.65 milliradians or less, 0.60 milliradians or less, or 0.55 milliradians or less. When both substrates are wedge-shaped, the substrates may have substantially similar wedge angles within 0.001 milliradians, within 0.005 milliradians, or within 0.01 milliradians of each other. Alternatively, if both are wedged, one of the wedged substrates may have a different wedge angle than the other.

[0096] Examples of suitable types of multilayer panels may include windows for automotive applications, including, but not limited to, windshields, side windows, and sunroofs. Examples of suitable types of multilayer panels for architectural applications include, but are not limited to, laminated glass panels for windows, doors, walls, ceilings, and walkways. [Example]

[0097] Example 1 - High refractive index poly(vinyl acetal) resin Several poly(vinyl acetal) resins, referred to as comparative or control resins CR1-CR6 in Table 1 below, were prepared by acetalizing polyvinyl alcohol with one or more aldehydes, including n-butylaldehyde (n-ButCHO, RI=1.377) and benzaldehyde (BzCHO, RI=1.545). Benzaldehyde was used as a control aromatic monomer for polyvinyl acetal to demonstrate its low reactivity with polyvinyl alcohol due to its fully conjugated structure. Substitution of alkyl, aryl, or halogen on the aromatic ring of benzaldehyde can improve reactivity with polyvinyl alcohol.

[0098] Additionally, several poly(vinyl acetal) resins according to embodiments of the present invention were also synthesized. The resins of the present invention, designated IR1-IR5 in Table 1, were prepared by acetalizing polyvinyl alcohol with a mixture of n-butyraldehyde and various high refractive index aldehydes, including 4-methylbenzaldehyde (4-MBzCHO, RI=1.545), cinnamaldehyde (CCHO, RI=1.620), and 2-hydroxy-1-naphthaldehyde (2-Hy-1-NCHO, RI=1.652).

[0099] [Table 1]

[0100] Example 2 - Synthesis of Polyvinyl Acetal Using Cyclic Aldehyde Poly(vinyl acetal) was synthesized in a jacketed 2 L kettle reactor equipped with an overhead stirrer, condenser, addition funnel, and temperature probe for temperature monitoring. 115 g of polyvinyl alcohol (99% hydrolyzed) was dissolved in 1323 g of water by stirring at 150 rpm and 90°C for 1 hour to obtain a clear solution. After the polyvinyl alcohol was dissolved, the reaction mixture was cooled to 8°C. 149.5 g of n-butyraldehyde was then added via addition funnel over 1 minute and stirred at 150 rpm and 8°C for 30 minutes.

[0101] The concentrated inorganic acid catalyst solution (24.058 g of concentrated inorganic acid catalyst + 24.058 g of DI water) was rapidly added through the addition funnel over approximately 2 minutes, and the reaction mixture was stirred at 750 rpm for 15 minutes at 8°C until the agitator torque suddenly decreased to a minimum (a decrease in solution viscosity). After stirring for an additional 15 minutes, the bath temperature was then set to 70-80°C and the reaction mixture was heated for an additional 2-2.25 hours. The reaction mixture was cooled to room temperature, and the poly(vinyl acetal) resin was collected by vacuum filtration. The resin was then washed with 1.6 L of deionized water, and the solid resin was mixed with DI water with continuous stirring to remove residual acid using potassium hydroxide solution, followed by neutralization to a pH of 7-7.4 with the dropwise addition of KOH solution. Once neutralized, the resin was collected by vacuum filtration and dried overnight in a vacuum oven at 55°C. The dried resin was then ground to a 1 mm particle size using a ZM 200 Ultra Centrifugal Mill (Retsch®).

[0102] Poly(vinyl acetal) resins were similarly prepared according to Table 2 for CR2-CR6 and IR1-IR5 resins using mixtures of aliphatic and aromatic aldehydes.

[0103] [Table 2]

[0104] Example 3 - Characterization of Polyvinyl Acetal Resin 1The composition of the resulting resin was determined using H-NMR quantitative analysis. Samples were prepared by dissolving 20–30 mg of PVB in 1 mL of deuterated DMSO. Then, 100 μL of 1,4-dimethoxybenzene solution (DMB, 19.6 mg in 3 mL of DMSO-d6) was added and used as a chemical shift reference. The sample was heated to 80°C and stirred until completely dissolved. The sample was then transferred hot to an NMR tube and analyzed on a Bruker Avance III 600 MHz instrument (64 scans, 20-second delay, 80°C). The sample was analyzed using a 600 MHz BBFO probe. 1 The resins were analyzed by H-NMR spectroscopy. The amounts of aliphatic and aromatic polyvinyl acetals in the resins were determined by comparing the integrals of the signals between 0.5 ppm and 7.5 ppm.

[0105] The thermal properties of the resulting resins were determined by differential scanning calorimetry (ASTM D3418-21) by scanning from -55°C to 250°C at a scan rate of 10°C / min. The instrument used was a TA Instruments Q2000 DSC equipped with an RCS chiller unit. Standard aluminum pans and non-hermetic lids were used. Sample weights ranged from 3 to 7 mg. A preliminary thermal cycle was performed and recorded by heating the sample from -55°C to 255°C at a rate of 10°C / min to erase any previous thermal history. The temperature was held for 2 minutes (see Note 6, ASTM D3418-21). The sample was quenched to at least -55°C below the desired transition temperature. The temperature was held for 0.5 minutes. Heating was repeated at a rate of 10°C / min, and the heating curve was recorded until all desired transitions were complete. The Tg was determined by the midpoint of the change in baseline heat flow as a function of temperature in the second heating cycle.

[0106] The weight-average molecular weight (kg / mol) of the PVB resin was measured by gel permeation chromatography (GPC) using 20 mM potassium trifluoroacetate in hexafluoroisopropanol (HFIP solvent) at 40°C (flow rate: 1.0 ml / min, sample solution: 20 mg sample in 10 ml hexafluoroisopropanol containing 20 mM potassium trifluoroacetate + 10 μl isopropanol flow marker, injection volume: 10 μl, column set: Polymer Laboratories 5 μm HFIP gel guard and mixed HFIP gel).

[0107] The following information provides detection and instrumentation details. ■ Detection Refractive index set at 40°C Peak width setting >0.2 min (response time 4 sec) (2.28 Hz) Attenuation 31250nRIU Zero offset 5% Calibration material: Monodisperse polymethyl methacrylate standard material, MW=580~3,000,000g / mol ■ Equipment: Autosampler: Agilent Series 1100 Autosampler Column oven: Agilent series 1100 column oven Pump: Agilent Series 1100 isocratic pump Detector: Agilent series Refractive Index

[0108] The refractive index of a polyvinyl acetal resin film containing 75 parts of plasticizer per 100 parts was measured. A plasticized resin film was prepared by weighing 20 g of resin and 15 g of TEG-EH (triethylene glycol bis(2-ethylhexanoic acid)) plasticizer into a plastic cup. The resin and plasticizer were thoroughly mixed, and then the mixture was compounded in a Brabender mixer at 170°C and 50 rpm for 7 minutes. The resin and plasticizer compound was then pressed into a 30-mil thick film using a hydraulic or pneumatic press. The press temperature was set at 180°C. A 5-mil PET film was placed on a first metal plate, and then a 3" x 3" 30-mil shim was placed on top of the PET film. Five grams of the compounded resin and plasticizer mixture was weighed, and the compounded resin was spread onto the shim. A second piece of PET film was placed on top of the shim containing the resin / plasticizer compound, and then a second metal plate was placed on top of that. The assembly was placed in a press and pressed at 180°C and 2000 psi for 5 minutes. The press was cooled to approximately 40-50°C, then the pressure was released and the assembly removed from the press. The resulting 3" x 3" 30-mil-thick pressed film was removed from the metal shim and cut into 1- to 2-inch square pieces for RI measurements. RI measurements were performed using a Metricon Model 2010 Prism Coupler. Sample sizes of 1- to 2-inch squares were preferred, or cut as needed. The sample was then wiped clean with a Kimwipe and attached to the instrument via a plunger that pressed the sample flat against the prism. The plunger pressure was adjusted depending on the sample's stiffness or flexibility (higher for stiffer, lower for more flexible). The refractive index of the poly(vinyl acetal) film was measured at a wavelength of 589.3 nm. These RI values ​​were then compared to the RI of the PVB skin resin. The skin resin is a polyvinyl butyral resin using 18.5% PVOH as the top middle layer of a three-layer series. The RI of the PVB skin resin without plasticizer was 1.490 at 589.3 nm, and the RI of the PVB skin + 38 phr plasticizer was 1.483 at 589.3 nm.

[0109] The glass transition temperature of a 30 mil thick plasticized PVB film (PVB resin + 75 phr plasticizer) was measured by dynamic mechanical thermal analysis (DMTA) in shear mode at an oscillation frequency of 1 Hz and a temperature sweep rate of 3°C / min from -40°C to 80°C. DMTA measured the tan delta of the sample as a function of temperature at a given oscillation frequency and temperature sweep rate. The peak value of the tan delta curve was taken as the glass transition temperature. The analytical results and compositions of the comparative and inventive resins are shown in Table 3 below.

[0110] [Table 3]

[0111] Using the procedure described above, additional films were made by blending the skin resin with a selected resin (CR1, IR2, IR5) (second resin) and plasticizer from Table 1. The haze values ​​of the pressed films were then measured from 360 to 780 nm using a Hunterlab UltraScan Vis instrument, illuminant C / 2 and full transmission mode type, according to ASTM D1003 Section 8 Procedure B. The results are shown in Table 4. Method Steps: 1. The device was standardized using air. 2. Checked air standards to ensure equipment was properly standardized. 3. The PVB film was wiped clean using lint-free Kimwipes to ensure it was free of fingerprints and other smudges. 4. The PVB film was placed against the transmission port and analyzed to obtain the haze value.

[0112] [Table 4] The haze value of the second resin-free skin layer with plasticizer (38 phr) and n-butyraldehyde was 0.05%. conclusion 1. Polyvinyl acetal prepared with aromatic (cyclic) aldehydes showed a higher refractive index at 589.3 nm compared with aliphatic aldehyde (CR1) resin. 2. Polyvinyl acetal prepared with aromatic (cyclic) aldehydes increased the molecular weight and glass transition temperature of the resin. 3. Plasticized polyvinyl acetal prepared with aromatic (cyclic) aldehydes increased the glass transition temperature. 4. Benzaldehyde was used as a comparative example of an aromatic (cyclic) aldehyde, and NMR analysis showed that it had low reactivity with polyvinyl alcohol. This may be due to its conjugate structure. However, incorporating benzaldehyde increased the refractive index of the polyvinyl acetal resin. 5. Alkyl and aryl substitution on the benzaldehyde ring improved reactivity with polyvinyl alcohol. 4-Methylbenzaldehyde showed a very good increase in refractive index (DR2, DR4, and DR5). The refractive index difference (skin-core) was reduced in the resins of the present invention (DR2, DR3, DR4, and DR5). However, the DR3 cyclic aldehyde was less reactive with polyvinyl alcohol. 6. Some other cyclic aldehydes that may act to increase the refractive index and decrease the skin-core RI are 4-methoxybenzaldehyde (MeBzCHO, RI=1.578) and p-phenylbenzaldehyde (P-PhBzCHO, RI=1.5994). 7. Due to differences in polyvinyl butyral composition between the skin and core layers of multilayer PVB interlayers, multilayer film scrap cannot be re-extruded. If left as is, the resulting blend resin composition exhibits high levels of haze, resulting in unacceptable visual quality in the final interlayer product. As a result, large-scale recycling of multilayer interlayer materials has not been successful. The haze value of these interlayers / films can be improved by adding a polyvinyl acetal resin with a cyclic aldehyde to the skin resin. 8. Haze (Table 4) was significantly improved for films made by blending the skin resin with a resin selected from the second resin containing aromatic / cyclic aldehydes (Examples 15, 16, 17) compared to films made by blending the skin resin with the control resin (Examples 12, 13, 14).

[0113] definition It should be understood that the following is not intended to be an exhaustive list of defined terms. Other definitions may be provided in the preceding description, for example, when accompanying the use of a defined term in context.

[0114] As used herein, the term "modified polyvinyl acetal resin" refers to a polyvinyl acetal resin that contains residues of at least one cyclic aldehyde.

[0115] As used herein, the term "polyvinyl acetal resin component" can refer to an individual polyvinyl acetal resin present in a physical blend of two or more resins, or to the acetal moieties present on a single polyvinyl acetal resin.

[0116] As used herein, the term "polymer backbone" or "backbone" refers to the longest continuous chain of atoms bonded together in a polymeric compound.

[0117] As used herein, the term "side chain" or "pendant group" refers to a group of two or more atoms joined together and extending from the backbone of a polymeric compound.

[0118] As used herein, the term "substituted" refers to at least one atom or functional group in a molecule being replaced with a different atom or functional group to form a new compound.

[0119] As used herein, the term "ring" or "cyclic compound" refers to at least three atoms joined together in the form of a ring or ring system.

[0120] As used herein, the term "unsaturated" means having at least one C—C double bond.

[0121] As used herein, the term "saturated" means having no C—C double bonds.

[0122] As used herein, the term "conjugated" means having at least two CC double bonds separated by one CC single bond.

[0123] As used herein, the term "cyclic vinyl monomer" refers to a monomer that contains a vinyl group (-CH2=CH-) and at least one cyclic group.

[0124] As used herein, the term "heteroatom" refers to an atom other than carbon in a ring of a cyclic compound.

[0125] As used herein, the term "heterocyclic" refers to a ring group that contains at least two different types of atoms in the ring.

[0126] As used herein, the term "five-membered ring" refers to a molecule having a ring structure formed by five atoms bonded together.

[0127] As used herein, the term "six-membered ring" refers to a molecule having a ring structure formed by six atoms bonded together.

[0128] As used herein, the term "aromatic" refers to a planar unsaturated ring structure.

[0129] As used herein, the term "derivative" refers to a chemical compound derived from another chemical compound by chemical modification.

[0130] As used herein, the term "polymer backbone" or "backbone" refers to the longest continuous chain of atoms bonded together in a polymeric compound.

[0131] As used herein, the term "side chain" or "pendant group" refers to a group of two or more atoms joined together and extending from the backbone of a polymeric compound.

[0132] As used herein, the term "refractive index" refers to the ratio of the speed of light in a vacuum to the speed of light through a material of interest. Unless otherwise specified, as used herein, refractive index is measured at a wavelength of 589 nm at 25°C according to ASTM D542.

[0133] As used herein, "glass transition temperature" or "Tg" is the temperature that characterizes the transition of a polymer from a glassy to a rubbery state. The glass transition temperatures described herein are determined by dynamic mechanical thermal analysis (DMTA). DMTA measures a specimen's storage (elastic) modulus in Pascals (G'), loss (viscous) modulus in Pascals (G"), and tan delta (G" / G') as a function of temperature at a given oscillation frequency and temperature sweep rate. The glass transition temperature is then determined by the location of the tan delta peak on the temperature scale. Specific glass transition temperatures provided herein were determined in shear mode at an oscillation frequency of 1 Hz and a temperature sweep rate of 3°C / min, unless otherwise noted.

[0134] As used herein, the term "parts per hundred parts of resin" or "phr" refers to the amount of an ingredient (e.g., plasticizer, additive, etc.) present in a composition relative to 100 parts of resin, on a weight basis.

[0135] As used herein, the term "residual hydroxyl content" refers to the amount of hydroxyl groups remaining on the polyvinyl acetal resin after processing is complete. Residual hydroxyl content is expressed as a weight percent based on the weight of the polyvinyl acetal resin and is measured in accordance with ASTM D-1396, unless otherwise specified.

[0136] As used herein, the term "residual acetyl content" refers to the amount of acetyl groups remaining on the polyvinyl acetal resin after processing is complete. Residual acetyl content is expressed as a weight percent based on the weight of the polyvinyl acetal resin and is measured according to ASTM D-1396, unless otherwise specified.

[0137] As used herein, the term "residue" or "moiety" refers to a portion of a polymer, typically resulting from the reaction of one or more monomers.

[0138] As used herein, the term "aliphatic" refers to molecules, including saturated or unsaturated molecules, that do not contain aromatic groups.

[0139] As used herein, the term "haze" or "haze value" refers to a value that quantifies the amount of light scattered by a sample relative to incident light. Haze is measured at a 2-degree observer angle using Illuminant C according to ASTM D1003-13-Procedure B, unless otherwise specified. Testing is performed using a spectrophotometer such as a Hunterlab UltraScan XE instrument (commercially available from Hunter Associates, Reston, Va.) on a 0.76 mm thick polymer sample laminated between two sheets of clear glass (commercially available from Pittsburgh Glass Works, Pennsylvania), each 2.3 mm thick.

[0140] As used herein, the term "resin composition" refers to a composition that includes one or more polymeric resins.

[0141] As used herein, the term "resin layer" refers to one or more polymeric resins, optionally in combination with one or more plasticizers, formed into a polymer sheet.

[0142] As used herein, the term "interlayer" refers to a single or multi-layer polymer sheet suitable for use with at least one rigid substrate to form a multi-layer panel.

[0143] As used herein, the terms "single-sheet" interlayer and "monolithic" interlayer refer to an interlayer formed from one single sheet of resin.

[0144] As used herein, the terms "multi-layer" and "multi-layer" interlayer refer to an interlayer having two or more resin sheets that are coextruded, laminated, or otherwise bonded together.

[0145] As used herein, the term "molecular weight" or "MW" refers to weight average molecular weight as measured by the Cotts and Ouano size exclusion chromatography with low angle laser light scattering (SEC / LALLS) method, unless otherwise specified.

[0146] As used herein, the term "different from" can refer to a value that is higher or lower than another value, calculated by subtracting one value from the other.

[0147] As used herein, the term "vertical cross section" refers to a cross section taken between the upper and lower edges of the interlayer when it is positioned in an installed configuration when laminated in a windshield or other end use.

[0148] As used herein, the terms "Cx" or "Cx hydrocarbon" or "Cx component" refer to hydrocarbon compounds containing "x" total carbons per molecule and include all olefins, paraffins, aromatics, heterocycles, and isomers having that number of carbon atoms. For example, normal, iso, and tert-butane, as well as butene and butadiene molecules, each fall under the general description "C4" or "C4 component."

[0149] As used herein, the term "predominantly" means greater than 50 weight percent. For example, a predominantly propane stream, composition, feed, or product is a stream, composition, feed, or product that contains greater than 50 weight percent propane.

[0150] As used herein, the terms "a," "an," and "the" mean one or more.

[0151] As used herein, when used in a list of two or more items, the term "and / or" means that any one of the listed items can be used by itself, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A only, B only, C only, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C.

[0152] As used herein, the phrase "at least a portion" is inclusive of at least a portion, up to and including the entire amount or period.

[0153] As used herein, the terms "comprising," "comprises," and "comprise" are open-ended transitional phrases used to transition the subject matter listed before the term to one or more elements listed after the term, and the element or elements listed after the transitional phrase are not necessarily the only elements that make up the subject matter.

[0154] As used herein, "including," "include," and "included" have the same open-ended meaning as "comprising," "comprises," and "comprise" above.

[0155] As used herein, the term "recycled content" refers to a composition that is or includes a material that is directly and / or indirectly derived from recycled materials. Recycled content is generally used to refer to both physically recycled content and credit-based recycled content. Recycled content is also used as an adjective to describe materials that have physically recycled content and / or credit-based recycled content.

[0156] As used herein, the term "polyvinyl acetal resin component" can refer to an individual polyvinyl acetal resin present in a physical blend of two or more resins, or to the acetal moieties present on a single polyvinyl acetal resin.

[0157] As used herein, the term "unmodified polyvinyl acetal resin" refers to a polyvinyl acetal resin that contains at least 99 percent by weight of residues of vinyl acetate, polyvinyl alcohol, and at least one aldehyde, and that contains no residues of cyclic vinyl acetal monomers.

[0158] Claims not limited to the disclosed embodiments The above-described preferred embodiments of the present invention are merely used as an illustration and should not be used to limit the scope of the present invention. Modifications to the above-described exemplary embodiments can be easily made by those skilled in the art without departing from the spirit of the present invention.

[0159] The inventors state herein that they intend to rely on the doctrine of equivalents to determine and assess the reasonable equitable scope of the invention as it relates to any device that departs, but does not depart substantially, from the literal scope of the invention as set forth in the following claims.

Claims

1. A polyvinyl acetal resin composition, a polyvinyl acetal resin component comprising the residue of at least one cyclic aldehyde having an unsaturated 5- or 6-membered ring group, and another polyvinyl acetal resin component comprising the residue of at least one C3 to C8 aliphatic aldehyde; and at least one plasticizer, The polyvinyl acetal resin composition comprising:

2. 1. A method for producing a polyvinyl acetal resin component, the method comprising at least one of the following steps (a) and (b): (a) acetalizing polyvinyl alcohol with at least one C3-C8 aliphatic aldehyde and at least one cyclic aldehyde to form a modified polyvinyl acetal resin, wherein the cyclic aldehyde comprises (i) an unsaturated 5- or 6-membered ring and / or (ii) a heterocyclic ring; and / or (b) blending a polyvinyl acetal resin comprising residues of a cyclic aldehyde and / or heterocycle with another polyvinyl acetal resin comprising at least 50 weight percent residues of a C3 to C8 aliphatic aldehyde to form a blended polyvinyl acetal resin composition.

3. 10. The composition, layer, interlayer or method of any preceding claim, wherein the cyclic aldehyde comprises a saturated ring.

4. 10. The composition, layer, interlayer or method of any preceding claim, wherein the cyclic aldehyde comprises an unsaturated ring.

5. 10. The composition, layer, interlayer or method of any preceding claim, wherein the cyclic aldehyde is a heterocyclic aldehyde.

6. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the cyclic aldehyde comprises a ring having 30 or fewer carbon atoms.

7. 10. The composition, layer, interlayer or method of any preceding claim, wherein the cyclic aldehyde comprises a ring having only carbon atoms.

8. 10. The composition, layer, interlayer or method of any preceding claim, wherein the cyclic aldehyde comprises a conjugated ring.

9. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the residues of the cyclic aldehyde are present in the polyvinyl acetal resin in an amount of at least 1 weight percent and / or no more than 50 weight percent, based on total aldehyde residues of the polyvinyl acetal resin.

10. 10. The composition, layer, interlayer or method of any preceding claim, wherein the refractive index of the cyclic aldehyde or heterocyclic aldehyde is at least 1.

500.

11. 10. The composition, layer, interlayer or method of any preceding claim (claim 3 and dep), wherein the second polyvinyl acetal resin has a refractive index (RI) of at least 1.

480.

12. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the second polyvinyl acetal resin has a residual hydroxyl content of at least 8.5 weight percent and / or less than 16 weight percent.

13. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the first and / or second polyvinyl acetal resins have a weight average molecular weight (Mw) of at least 100,000 Daltons and / or up to 1,000,000 Daltons.

14. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the first polyvinyl acetal resin comprises at least 0.5 weight percent and / or no more than 35 weight percent residual acetyl groups.

15. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the polyvinyl acetal resin composition or the first and / or second polyvinyl acetal resin layers comprise at least one plasticizer having a refractive index at 589 nm of at least 1.435 and / or no greater than 1.

530.

16. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the plasticizer is selected from the group consisting of triethylene glycol di(2-ethylhexanoate), triethylene glycol di(2-ethylbutyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, tetraethylene glycol di(2-ethylhexanoate), dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, diisononyl adipate, heptylnonyl adipate, di(butoxyethyl) adipate, and bis(2-(2-butoxyethoxy)ethyl adipate), dibutyl sebacate, dioctyl sebacate, and mixtures thereof.

17. The plasticizer may be selected from the group consisting of dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diethylene glycol benzoate, butoxyethyl benzoate, butoxyethoxyethyl benzoate, butoxyethoxyethoxyethyl benzoate, propylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol benzoate isobutyrate, 1,3- 10. The composition, layer, interlayer, or method of any preceding claim, wherein the carboxylic acid is selected from the group consisting of butanediol, 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, bisphenol A bis(2-ethylhexanoate), di-(butoxyethyl) terephthalate, di(butoxyethoxyethyl) terephthalate, and mixtures thereof.

18. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the first and second polyvinyl acetal resin layers have a difference in refractive index of 0.0100 or less.

19. 10. The composition, layer, interlayer, or method of any preceding claim, wherein the plasticizer is present in the first polyvinyl acetal resin composition or layer in an amount of at least 20 phr and / or no more than 45 phr.

20. 10. The composition, layer, interlayer, or method of any preceding claim, further comprising a blended polyvinyl acetal resin layer comprising said blended resin composition.

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