Multilayer sound-damping interlayer containing ethylene vinyl acetal

Abstract

The present invention relates to a multilayer sound-damping interlayer comprising ethylene vinyl acetal.

Description

Technical Field

[0005]

[0001] The present invention relates to a multilayer sound attenuation interlayer containing ethylene vinyl acetal.

Background Art

[0002] Laminated safety glass (LSG) generally consists of two glass panels and an interlayer that adheres the glass panels. Partially acetalized polyvinyl alcohol containing a plasticizer, particularly polyvinyl butyral (PVB), is mainly used as the film material. LSG is used, for example, as a windshield or side window in the automotive field and as safety glass in the construction field.

[0003] The sound attenuation characteristics of laminated glass are becoming increasingly important as a feature thereof. This can be achieved, for example, particularly by a soft and sound-absorbing single-layer film. However, the mechanical stability of these films is generally insufficient, and they do not exhibit sufficient adhesion to glass.

[0004] Alternatively, since the individual layers differ in terms of their mechanical strength, a multilayer system in which sound absorption is achieved by mechanical decoupling can be used. Such a multilayer system containing PVB is described, for example, in US Patent Application Publication No. 2010 / 028642.

[0005] However, there is still a need in the industry for an improved sound attenuation interlayer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, one object of the present invention is to provide an interlayer film with improved sound attenuation characteristics, improved mechanical stability, improved environmental footprint, improved thermal stability, improved water incorporation profile, improved processability during film formation, or improved manufacturing cost or raw material cost.

[0008] These and other objectives are remarkably addressed by the present invention. [Means for solving the problem]

[0009] In a first aspect, the present invention relates to a sound-attenuating interlayer for laminated glass comprising at least two individual films, wherein at least one of the individual films comprises ethylene vinyl acetal. [Modes for carrying out the invention]

[0010] Preferably, the sound-attenuating interlayer contains ethylene vinyl acetal with an ethylene unit content in the range of 25 to 60 mol%. More preferably, the proportion of ethylene units in the ethylene vinyl acetal is 30 to 55 mol%, and even more preferably 35 to 50 mol%.

[0011] Preferably, the proportion of ethylene units in ethylene vinyl alcohol is 25 to 60 mol%, more preferably 30 to 55 mol%, and even more preferably 35 to 50 mol%.

[0012] Preferably, the sound-attenuating interlayer includes at least three individual membranes, the first individual membrane (A) and the third individual membrane (C) constituting the outer layer, and the second individual membrane (B) constituting the inner layer.

[0013] Preferably, the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and more preferably, the first individual membrane (A), the second individual membrane (B), and the third individual membrane (C) contain ethylene vinyl acetal.

[0014] Accordingly, this embodiment of the present invention relates to a multilayer film comprising two outer layers containing ethylene vinyl acetal facing the glass when used as an interlayer for laminated safety glass, and at least one inner layer. The inner layer is usually selected to be softer than the two outer layers and is often referred to as a sound-attenuating layer. When all individual films contain ethylene vinyl acetal, the ethylene vinyl acetal is usually of different grades, for example, differing in the amount of ethylene units in the polymer chain, degree of acetalization and / or degree of saponification.

[0015] Preferably, ethylene vinyl alcohol is obtained by copolymerizing ethylene and vinyl acetate, and then hydrolyzing the resulting copolymer. Conventional alkaline catalysts and acid catalysts can be used in the hydrolysis reaction, and among these, hydrolysis reactions using methanol and caustic soda (NaOH) catalysts as solvents are convenient.

[0016] The method for producing ethylene vinyl acetal used in this embodiment of the present invention is not particularly limited, but it can be produced by adding an aldehyde to an ethylene vinyl alcohol solution under acidic conditions and subjecting it to an acetalization reaction.

[0017] The reaction product obtained after the acetalization reaction is neutralized with alkali and washed with water to obtain ethylene vinyl acetal.

[0018] The catalyst for the acetalization reaction is not particularly limited, and any organic or inorganic acid may be used. Examples include acetic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, hydrochloric acid, and carbonic acid.

[0019] The degree of saponification of the acetate group is not particularly limited, but is preferably 95 mol% or more, more preferably 98 mol% or more, even more preferably 99 mol% or more, and most preferably 99.9 mol% or more.

[0020] Preferably, the proportion of vinyl alcohol units in the ethylene vinyl acetal resin of the present invention is 20 to 71 mol% based on the total monomer units constituting the resin.

[0021] The degree of acetalization of the ethylene vinyl acetal used in the present invention is preferably 1 mol% to 80 mol%, preferably 5 mol% or more and less than 70 mol%, more preferably the lower limit of the degree of acetalization is greater than 6 mol%, greater than 7 mol%, greater than 8 mol%, greater than 9 mol%, and most preferably greater than 10 mol%. Furthermore, the upper limit of the degree of acetalization is more preferably 38 mol% or less, 36 mol% or less, 34 mol% or less, and 32 mol% or less, in that order, and most preferably less than 30 mol%. Another preferred degree of acetalization is 30 to 50 mol%.

[0022] Preferably, the acetal groups each have 1 to 7 carbon atoms, i.e., they originate from a condensation reaction with an aldehyde having 1 to 7 carbon atoms. More preferably, they are methanal (formaldehyde), acetaldehyde, n-propanal (propionaldehyde), n-butanal (butyraldehyde), iso-butanal (2-methyl-1-propanal, iso-butyraldehyde), n-pentanal (valeraldehyde), iso-pentanal (3-methyl-1-butanal), sec-pentanal (2-methyl-1-butanal), tert-pentanal (2,2-dimethyl-1-propanal), n-hexanal (caproaldehyde), isohexanal (2-methyl-1-pentanal, 3-methyl-1-pentanal, 4-methyl-1-pentanal), 2,2-dimethyl-1-butanal, 2,3-dimethyl-1-butanal The list consists of 3,3-dimethyl-1-butanal, 2-ethyl-1-butanal, n-heptanal, 2-methyl-1-hexanal, 3-methyl-1-hexanal, 4-methyl-1-hexanal, 5-methyl-1-hexanal, 2,2-dimethyl-1-pentanal, 3,3-dimethyl-1-pentanal, 4,4-dimethyl-1-pentanal, 2,3-dimethyl-1-pentanal, 2,4-dimethyl-1-pentanal, 3,4-dimethyl-1-pentanal, 2-ethyl-1-pentanal, 2-ethyl-2-methyl-1-butanal, 2-ethyl-3-methyl-1-butanal, 3-ethyl-2-methyl-1-butanal, cyclohexylaldehyde, and benzaldehyde. Most preferably, they are derived from condensation reactions with iso-butyraldehyde or n-butyraldehyde.

[0023] Preferably, the ethylene vinyl acetal is a mixed acetal, i.e., it contains at least two different acetal groups. In other words, the ethylene vinyl acetal used in the present invention contains a first acetal group derived from the reaction of two hydroxy groups of each ethylene vinyl alcohol with one aldehyde, and at least a second acetal group obtained from the reaction of the other two hydroxy groups of each ethylene vinyl alcohol with a second aldehyde, and the first aldehyde is different from the second aldehyde. Preferred aldehydes are the same as those used for the acetals having one acetal group as described above.

[0024] Preferably, the ethylene vinyl acetal used in the process of the present invention has a glass transition temperature (Tg) of 30, 35, 40, 45, or 50 °C or higher. Also preferably, the Tg is 90, 75, 70, 65, 60, 55 °C. More preferably, the ethylene vinyl acetal used in the process of the present invention has a Tg of 30 - 90 °C, most preferably 35 - 75 °C, specifically 40 - 55 °C.

[0025] The glass transition temperature is determined by differential scanning calorimetry (DSC) using a heating rate of 10 K / min at a temperature interval of -50 °C to 200 °C in accordance with DIN 53765. The first heating ramp, followed by a cooling ramp, and then the second heating ramp were used. The position of the glass transition temperature was determined on the measurement curve related to the second heating ramp in accordance with DIN 51007. The DIN midpoint (Tg DIN) was defined as the intersection of the horizontal line at half-step height and the measurement curve. The step height was defined by the vertical distance between the two intersections of the central tangent and the baseline of the measurement curve before and after the glass transition.

[0026] The melting point (melting temperature, Tm) is measured by differential scanning calorimetry (DSC) in accordance with DIN EN ISO 11357-3:2018.

[0027] The vinyl alcohol and vinyl acetate content of ethylene vinyl acetal was determined in accordance with DIN ISO 3681 (acetate content) and DIN ISO 53240 (PVA content). The vinyl acetal content can be calculated as the sum of the vinyl alcohol and vinyl acetate content determined in accordance with DIN ISO 53401 / 53240, plus the remainder from the total ethylene required to make 100. The degree of acetalization can be calculated by dividing the vinyl acetal content by the sum of the vinyl alcohol content, vinyl acetal content, and vinyl acetate content. Conversion from weight percent to mole percent can be performed using formulas known to those skilled in the art.

[0028] The ethylene content of ethylene vinyl acetal resin is measured by NMR spectroscopy. First, ethylene vinyl acetal resin is dissolved in ethanol, and 2N hydroxylamine hydrochloride solution and hydrochloric acid are added. The mixture is stirred under reflux in a condenser in a water bath for 4 hours, cooled, and then ammonia water is added. Methanol is then added to precipitate the polymer, which is washed with water and dried to obtain ethylene vinyl alcohol copolymer. Next, this ethylene vinyl alcohol copolymer is dissolved in DMSO (dimethyl sulfoxide) at 120°C, cooled to room temperature, and then N,N-dimethyl-4-aminopyridine and acetic anhydride are added. The mixture is stirred for 1 hour, then precipitated with deionized water and acetone, and dried to obtain ethylene vinyl acetate copolymer. This polymer is dissolved in DMSO-d6 and measured with a 400 MHz proton NMR spectrometer. The obtained spectrum is integrated 256 times. The molar ratio of ethylene units in ethylene-vinyl alcohol copolymer is calculated from the intensity ratio of methine protons (peaks of 1.1-1.9 ppm) derived from ethylene units and vinyl acetate units, and terminal methyl protons (peaks of 2.0 ppm) derived from vinyl acetate units. Since ethylene units are not affected by the acetalization reaction, the molar ratio (n) of ethylene units in ethylene vinyl alcohol copolymer before the acetalization reaction is equal to the molar ratio (n) of ethylene units in the ethylene vinyl acetal resin obtained after the acetalization reaction.

[0029] Furthermore, the interlayer of the present invention may contain other polymers different from the ethylene vinyl acetal described above. It may contain one or more other ethylene vinyl acetal grades that differ in hydroxyl content, ethylene content, acetate content and / or degree of polymerization and / or degree of acetalization and / or type of acetal. Alternatively, it may also contain any polymer selected from the group consisting of polyvinyl acetal and mixtures thereof, such as polylactic acid (PLA), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene terephthalate copolymer (PETG), polyhydroxyalkanoate (PHA), wood-filled composites, metal-filled composites, carbon fiber-filled composites, thermoplastic elastomers (TPE), thermoplastic polyurethanes (TPU), polyolefins, polypropylene (PP), acrylonitrile styrene acrylate (ASA), polyacrylate, polymethacrylate, ionomer, polybutyral, and polyvinyl acetal.

[0030] Preferably, the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and the second individual membrane (B) contains a thermoplastic elastomer.

[0031] Thermoplastic elastomers generally include materials having a soft segment and a hard segment, such as polystyrene elastomers (soft segment: polybutadiene, polyisoprene / hard segment: polystyrene), polyolefin elastomers (soft segment: ethylene propylene rubber / hard segment: polypropylene), polyvinyl chloride elastomers (soft segment: polyvinyl chloride / hard segment: polyvinyl chloride), polyurethane elastomers (soft segment: polyether, polyester, or polycarbonate / hard segment: polyurethane), and polyester elastomers (soft segment: aliphatic polyester / hard segment: aromatic polyester). Examples include polyether ester elastomers (soft segment: polyether / hard segment: polyester), polyamide elastomers (soft segment: polypropylene glycol, polytetramethylene ether glycol, polyester, or polyether / hard segment: polyamide (e.g., nylon resin)), polybutadiene elastomers (soft segment: amorphous butyl rubber / hard segment: syndiotactic 1,2-polybutadiene resin), acrylic elastomers (soft segment: polyacrylate ester / hard segment: polymethyl methacrylate), etc. The above thermoplastic elastomers may be used individually or in combination of two or more.

[0032] The hard segment content in the thermoplastic elastomer is preferably about 5% by mass or more, or about 7% by mass or more, or about 8% by mass or more, or about 10% by mass or more, or about 14% by mass or more, or about 16% by mass or more, or about 18% by mass or more, relative to the total amount of thermoplastic elastomer. The hard segment content is preferably about 40% by mass or less, or about 30% by mass or less, or about 20% by mass or less, relative to the total amount of thermoplastic elastomer. If the hard segment content is less than about 5% by mass, it tends to be difficult to mold layer B, the peak height of tan d will be lower, the bending stiffness of the laminate will be reduced, or the sound insulation performance in the high-frequency range will be reduced. If the hard segment content exceeds about 40% by mass, the properties of the thermoplastic elastomer will be difficult to exhibit, the stability of the sound insulation performance will be reduced, or the sound insulation performance near room temperature will be reduced.

[0033] The soft segment content in the thermoplastic elastomer is preferably about 60% by mass or more, or about 70% by mass or more, or about 80% by mass or more, relative to the total amount of thermoplastic elastomer. The soft segment content is preferably about 95% by mass or less, or about 92% by mass or less, or about 90% by mass or less, or about 88% by mass or less, or about 86% by mass or less, or about 84% by mass or less, or about 82% by mass or less, relative to the total amount of thermoplastic elastomer. If the soft segment content is less than about 60% by mass, the properties of the thermoplastic elastomer tend not to be exhibited. If the soft segment content is greater than about 95% by mass, it tends to become difficult to mold layer B, the peak height of tan d decreases, the bending rigidity of the laminate decreases, or the sound insulation in the high-frequency range decreases. Here, when multiple thermoplastic elastomers are mixed, the hard segment and soft segment content in the thermoplastic elastomer are considered to be the average values ​​of the mixture, respectively.

[0034] From the viewpoint of achieving both moldability and sound insulation, it is more preferable to use a block copolymer having hard segments and soft segments as the thermoplastic elastomer. Furthermore, from the viewpoint of further improving sound insulation, it is preferable to use a polystyrene-based elastomer.

[0035] Furthermore, as thermoplastic elastomers, cross-linked rubbers such as natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, urethane rubber, silicone rubber, chlorosulfonated polyethylene rubber, acrylic rubber, and fluororubber may be used.

[0036] The thermoplastic elastomer is preferably a copolymer of an aromatic vinyl monomer and a vinyl monomer or a conjugated diene monomer, or a hydrogenated product of said copolymer. From the viewpoint of achieving both the function of a rubber exhibiting sound insulation properties and the function of a plastic, the copolymer is preferably a block copolymer having an aromatic vinyl polymer block and an aliphatic unsaturated hydrocarbon polymer block, such as a polystyrene-based elastomer.

[0037] When using a block copolymer as a thermoplastic elastomer, which comprises an aromatic vinyl polymer block and a vinyl polymer block or a conjugated diene polymer block, for example, an aromatic vinyl polymer block and an aliphatic unsaturated hydrocarbon polymer block, the bonding type of these polymer blocks is not particularly limited and may be linear, branched, radial, or a combination of two or more of these. Among these, the linear bonding type is preferred.

[0038] When aromatic vinyl polymer blocks are represented by "a" and aliphatic unsaturated hydrocarbon polymer blocks by "b", examples of linearly linked copolymers include diblock copolymers represented by ab, triblock copolymers represented by aba or bab, tetrablock copolymers represented by abab, pentablock copolymers represented by ababa or babab, (ab)nX type copolymers (where X is a coupling residue and n is an integer of 2 or more), and mixtures thereof. Among these, diblock copolymers or triblock copolymers are preferred, and of the triblock copolymers, triblock copolymers represented by aba are more preferred.

[0039] Examples of aliphatic unsaturated hydrocarbon monomers that make up aliphatic unsaturated hydrocarbon polymer blocks include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-phenyl-1-butene, 6-phenyl-1-hexene, 3-methyl-1-butene, 4-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-methyl-1-hexene, 4-methyl-1-hexene, 5-methyl Examples include 1-

[0040] The method for producing block copolymers is not particularly limited, but they can be produced by methods such as anionic polymerization, cationic polymerization, and radical polymerization. For example, in the case of anionic polymerization, specific examples include the following. (i) A method for sequentially polymerizing an aromatic vinyl monomer, a conjugated diene monomer, and then an aromatic vinyl monomer using an alkyllithium compound as an initiator. (ii) A method of sequentially polymerizing an aromatic vinyl monomer and a conjugated diene monomer using an alkyllithium compound as an initiator, followed by the addition of a coupling agent to perform coupling. (iii) A method for sequentially polymerizing a conjugated diene monomer followed by an aromatic vinyl monomer using a dilithium compound as an initiator.

[0041] Specific examples of suitable thermoplastic elastomers can be found, for example, by referring to U.S. Patent Application Publication No. 2010 / 239802.

[0042] In one preferred embodiment, the thermoplastic elastomer is at least (A) Polymer blocks mainly composed of aromatic vinyl compound units, and (B) Polymer blocks consisting mainly of 1,3-butadiene units, or mainly of isoprene units and 1,3-butadiene units. A hydrogenated block copolymer formed by hydrogenating a block copolymer containing a polymer block (A), wherein the polymer block (A) content is about 5% to about 40% by mass based on the total amount of the hydrogenated block copolymer, the hydrogenation rate of polymer block (B) is about 70% or more, and the glass transition temperature of the hydrogenated block copolymer is about -45°C to about 30°C.

[0043] In another preferred embodiment, the thermoplastic elastomer is a hydrogenated block copolymer formed by hydrogenating a block copolymer comprising at least a polymer block (C) mainly composed of aromatic vinyl compound units and a polymer block (D) mainly composed of 1,3-butadiene units or mainly composed of isoprene units and 1,3-butadiene units, wherein the content of polymer block (C) is about 10% to about 40% by mass based on the total amount of the hydrogenated block copolymer, the hydrogenation rate of polymer block (D) is about 80% or more, and the glass transition temperature of the hydrogenated block copolymer is less than about -45°C.

[0044] In the two preferred embodiments described above, preferably the aromatic vinyl compound is styrene, and / or polymer blocks (B) and (D) are composed mainly of isoprene units and 1,3-butadiene units, and / or the hydrogenated block copolymer is a triblock copolymer having an A1-B-A2 or C1-D-C2 type structure.

[0045] In another embodiment of the present invention, the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and the second individual membrane (B) contains polyvinyl acetal.

[0046] Other aldehydes as described above can also be advantageously used, but preferably, the individual membrane (B) is based on polyvinyl butyral (PVB) obtained by acetalizing polyvinyl alcohol with butyraldehyde.

[0047] Preferably, the individual film (B) contains polyvinyl acetal with a polyvinyl acetate group portion of 5 to 8 mol%.

[0048] Preferably, the individual film (B) contains less than 18% by weight, more preferably less than 14% by weight, most preferably 11 to 13.5% by weight, specifically less than 11.5 to 13% by weight of polyvinyl acetal with polyvinyl alcohol groups.

[0049] Specific examples of suitable polyvinyl acetals can be found, for example, by referring to U.S. Patent Application Publication No. 2010 / 028642.

[0050] In another preferred embodiment, the second individual membrane (B) comprises ethylene vinyl acetal. Thus, the ethylene vinyl acetal is a softer core material supplemented by two harder outer membranes.

[0051] Preferably, the first individual membrane (A) and the third individual membrane (C) contain polyvinyl acetal.

[0052] Preferably, the polyvinyl acetal has a polyacetate group portion of 0.1 to 11 mol%, preferably 0.1 to 4 mol%, and more preferably 0.1 to 2 mol%.

[0053] Preferably, the polyvinyl acetal has a polyvinyl alcohol group portion of 17-22% by weight, preferably 18-21% by weight, and more preferably 19.0-20.5% by weight.

[0054] Specific examples of suitable polyvinyl acetals can be found, for example, by referring to U.S. Patent Application Publication No. 2010 / 028642.

[0055] In another preferred embodiment of the present invention, the first individual membrane (A) and the third individual membrane (C) comprise an ionomer.

[0056] The ionomer resin is a partially neutralized ethylene α,β-unsaturated carboxylic acid copolymer comprising a resin having constituent units derived from ethylene, constituent units derived from α,β-unsaturated carboxylic acid, and optionally other constituent units described below, wherein at least a portion of the constituent units derived from α,β-unsaturated carboxylic acid are neutralized by ions.

[0057] In the ethylene-α,β-unsaturated carboxylic acid copolymer that serves as the base polymer, the content of constituent units derived from α,β-unsaturated carboxylic acid is typically 2% by mass or more, or 5% by mass or more (based on the mass of the total copolymer). In addition, the content of constituent units derived from α,β-unsaturated carboxylic acid is typically 30% by mass or less (based on the mass of the total copolymer).

[0058] Examples of α,β-unsaturated carboxylic acids constituting an ionomer include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and mixtures of two or more of these. In one embodiment, the α-ethylenically unsaturated carboxylic acid is selected from acrylic acid, methacrylic acid, and mixtures thereof. In another embodiment, the α,B-ethylenically unsaturated carboxylic acid is methacrylic acid.

[0059] The ethylene-acid copolymer may further contain copolymerization units of one or more additional comonomers, such as a,b-ethylenically unsaturated carboxylic acid esters. If present, alkyl esters having 3 to 10 or 3 to 8 carbon atoms are usually used. Specific examples of suitable esters of unsaturated carboxylic acids include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, octyl acrylate, octyl methacrylate, undecyl acrylate, undecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, dodecyl acrylate Examples of comonomers include, but are not limited to, methyl acrylate, dodecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isovolumyl acrylate, isobornyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, dimethyl fumarate, vinyl acetate, vinyl propionate, and mixtures of two or more of these. In one embodiment, additional comonomers are selected from methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, glycidyl methacrylate, vinyl acetate, and mixtures of two or more of these. In another embodiment, the additional comonomer is one or more of n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, and isobutyl methacrylate. In yet another embodiment, the additional comonomer is one or both of n-butyl acrylate and isobutyl acrylate.

[0060] The melt flow rate (MFR) of a suitable ethylene acid copolymer, determined at 190°C and 2.16 kg according to ASTM method D1238-89, is approximately 1 or approximately 2, up to approximately 4000 g / 10 min, up to 1000 g / 10 min, or up to approximately 400 g / 10 min.

[0061] Finally, suitable ethylene acid copolymers can be synthesized, for example, as described in U.S. Patent No. 3,404,134, U.S. Patent No. 5,028,674, U.S. Patent No. 6,500,888, U.S. Patent No. 6,518,365, U.S. Patent No. 8,334,033 and U.S. Patent No. 8,399,096.

[0062] To obtain an ionomer, the ethylene acid copolymer is partially neutralized by reaction with one or more bases. Examples of preferred procedures for neutralizing the ethylene acid copolymer are described in U.S. Patent No. 3,404,134 and U.S. Patent No. 6,518,365. After neutralization, about 1%, or about 10%, or about 15%, or about 20% to about 90%, or about 60%, or about 55%, or about 30% of the hydrogen atoms of the carboxylic acid groups present in the ethylene acid copolymer are replaced with other cations. In other words, about 1%, or about 10%, or about 15%, or about 20% to about 90%, or about 60%, or about 55%, or about 30% of the total content of carboxylic acid groups present in the ethylene acid copolymer is neutralized. In other words, based on the total content of carboxylic acid groups present in the unneutralized ethylene acid copolymer, the neutralization is performed to levels ranging from approximately 1%, or approximately 10%, or approximately 15%, or approximately 20% to approximately 90%, or approximately 60%, or approximately 55%, or approximately 30%. The level of neutralization can be adjusted to suit the specific end application.

[0063] Ionomers contain a cation as a counterion to the carboxylate anion. Suitable cations include any positively charged species that are stable under the conditions under which the ionomer composition is synthesized, processed, and used. Suitable cations can be used in combination of two or more. In some preferred ionsomers, the cation is a metal cation and may be monovalent, divalent, bivalent, or polyvalent. Useful monovalent metal cations include, but are not limited to, sodium, potassium, lithium, silver, mercury, and copper. Useful divalent metal cations include, but are not limited to, beryllium, magnesium, calcium, strontium, barium, copper, cadmium, mercury, tin, lead, iron, cobalt, nickel, and zinc. Useful trivalent metal cations include, but are not limited to, aluminum, scandium, iron, and yttrium. Useful polyvalent metal cations include, but are not limited to, those of titanium, zirconium, hafnium, vanadium, tantalum, tungsten, chromium, cerium, and iron. When the metal cation is polyvalent, complexing agents such as stearates, oleates, salicylates, and phenolate radicals may be included, as described in U.S. Patent No. 3,404,134. In other preferred compositions, the metal cation used is monovalent or divalent. Preferred metal cations are sodium, lithium, magnesium, zinc, potassium, and combinations of one or more of these metal cations. In more preferred compositions, the cations are sodium cations, magnesium cations, zinc cations, and combinations thereof.

[0064] In one embodiment, the counterion for the carboxylate anion in the ionomer is a sodium cation, and other counterions may be present in small amounts of less than 5 equivalents, less than 3 equivalents, less than 2 equivalents, or less than 1 equivalent, based on the total equivalent amount of carboxylate groups in the ionomer. In one embodiment, the counterion is substantially a sodium ion.

[0065] Preferably, at least one of the individual membranes (A), (B), or (C) is wedge-shaped. More preferably, all of the individual membranes (A), (B), and (C) are wedge-shaped.

[0066] Accordingly, the present invention relates to a combination of wedge-shaped and non-wedge-shaped individual films, or to a partially or completely wedge-shaped interlayer based entirely on wedge-shaped individual films. Wedge-shaped interlayers are commonly used in automobiles equipped with head-up displays to prevent double images.

[0067] Preferably, at least one of the individual films (A), (B), and (C) contains 10 to 50% by weight of a plasticizer. Thus, the individual films contain, in addition to the polymer material, one or more plasticizers in up to 50% by weight (based on the total weight of the composition). Any compound known to plasticize the corresponding polymer can be used. Preferred plasticizers include diesters of aliphatic diols, particularly aliphatic polyether diols and / or polyether polyols, with aliphatic carboxylic acids, preferably diesters of polyalkylene oxides, particularly diesters of diethylene glycol, triethylene glycol and tetraethylene glycol, with aliphatic (C6-C10) carboxylic acids, preferably 2-ethylbutyric acid and n-heptanoic acid; and diesters of aliphatic or aromatic (C2-C18) dicarboxylic acids, preferably adipic acid, sebacic acid, phthalic acid, and aliphatic (C4-C12) alcohols, preferably dihexyl adipates, phthalates, trimellitates, phosphates, fatty acid esters, particularly triethylene glycol-bis-(2-ethylbutyrate) and triethylene glycol ethylhexanoate (3G8); aromatic carboxylic acid esters, particularly dibenzoates and / or hydroxycarboxylic acid esters. Particularly preferred plasticizers are ISOFOL 12+5 EO, which is 2-butyl octanol with an average ethoxylation degree of 5; dihexyl adipate (DHA); 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH); dipropylene glycol dibenzoate (DPGDB); diethylene glycol dibenzoate (MONOCIZER PB-3A); MONOCIZER PB-10; and mixtures thereof. Mixtures of different and identical compositions of plasticizers, as well as single plasticizers, may be included. The term "different compositions" refers to both the type and proportion of plasticizers in the mixture. In the starting state before lamination, the mixture may contain at least 22% by weight, for example, 22.0–45.0% by weight, preferably 25.0–32.0% by weight, and particularly 26.0–30.0% by weight of plasticizers.

[0068] Optionally, the interlayer of the present invention may also contain other components besides the ethylene vinyl acetal described above. For example, it may contain antioxidants, optical gloss agents, stabilizers, processing aids, organic or inorganic nanoparticles, exothermic silicic acid, silica, surface active substances and / or rheological modifiers.

[0069] The damping characteristics were determined in accordance with ISO 16940 for a test specimen consisting of a 0.8 mm thick interlayer laminated between 2 mm thick glass panels. Each time, a first mode was determined, and the corresponding loss factor for that first mode was determined.

[0070] The sound absorption effect of the film of the present invention must be highest at the application temperature of the future glass laminate. In the case of automotive glass, the application temperature is around 20°C because the windows are heated in winter and cooled in summer by the air conditioning unit. In the above test setup, the film of the present invention preferably shows maximum attenuation in the temperature range of 15 to 25°C. Preferably, the loss factor value is greater than 0.1, more preferably greater than 0.15, and most preferably greater than 0.2.

[0071] The method for manufacturing the interlayer film is not particularly limited. Specifically, the starting resin composition can be formed into a film by extrusion molding, blow molding, injection molding, solution casting, etc., preferably by extrusion molding. The resin temperature during extrusion is preferably 170 to 250°C, more preferably 180 to 240°C, and even more preferably 190 to 230°C. If the resin temperature becomes too high, the ethylene vinyl acetal resin will undergo partial decomposition.

[0072] The individual films used in accordance with the present invention can be used with substantially any thickness, as long as the sound insulation properties are not adversely affected. All individual films can have, for example, the same thickness, but combinations of individual films with different thicknesses are also possible. In one preferred arrangement of the interlayer films of the present invention as a three-layer film A / B / C, the outer films A and C have substantially the same thickness, while the sound-absorbing film B can be as thin as possible. If the total thickness of the multilayer film is 0.8 mm, the sound-absorbing film may be 0.05 to 0.35 mm thick. The multilayer film of the present invention preferably has a total thickness of, for example, 0.38, 0.76, or 1.14 mm (i.e., a multiple of 0.38 mm), which is common in the industry.

[0073] The interlayer film of the present invention has a certain roughness on at least one surface in order to prevent the interlayer films from sticking together when, for example, the film is wound onto a roll, and to improve degassing performance in the lamination process. This roughness can be provided using conventional methods. Examples include methods that create a melt fracture structure by adjusting the extrusion conditions or by embossing the surface. Conventional methods can be used for the depth and shape of the embossing.

[0074] A further aspect of the present invention relates to the use of the interlayer of the present invention as an adhesive film for laminated glass.

[0075] This laminated glass can be manufactured by inserting and laminating the interlayer film of the present invention, as well as at least one film containing polyvinyl acetal, between two or more sheets of glass made of inorganic or organic glass. There are no particular restrictions on the glass laminated to the interlayer film for laminated glass of the present invention, but in addition to inorganic glass such as float glass, tempered glass, wired glass, or heat-absorbing glass, conventionally known organic glass such as polymethyl methacrylate or polycarbonate can be used. There are no particular restrictions on the thickness of the glass, but it is preferably 1 to 10 mm, more preferably 2 to 6 mm.

[0076] Lamination methods for obtaining the above-mentioned laminated glass are known in the art, and examples include methods using a vacuum laminator, a vacuum bag, a vacuum ring, and a nip roll. Furthermore, a method of immersion in an autoclave after temporary bonding can also be added. [Examples]

[0077] For the purposes of the present invention, various glass / glass laminates are manufactured. They include the film of the present invention in the form of three combined individual films as an intermediate layer, with films A and C in direct contact with the glass surface and film B positioned between films A and C. Tables 1 and 2 show the composition of each membrane.

[0078] [Table 1]

[0079] [Table 2]

[0080] [Preparation of the interlayer film of the present invention] The interlayer of the present invention is manufactured by film extrusion techniques known to those skilled in the art. To achieve a multilayer structure, individual layers A and C are extruded using twin-screw extruder 1, and individual layer B is extruded using twin-screw extruder 2. Depending on the example (see the table above), the following amounts of di-(2-butoxyethyl)-adipic acid (DBEA) are supplied to the extruder.

[0081] Using a feed block positioned before the molten material from extruders 1 and 2 enters a 34 cm wide extrusion die, the layers are combined to form a three-layer film in which layers A and C have the same composition and layer B is in contact with both layers A and C. The molten material constituting the three-layer structure is extruded onto a cooled chill roll, relaxed, and wound onto a further uncooled roll to form a final interlayer film. The results of individual examples are shown in Table 2.

[0082] The formulation of Example 1.1 contains 15% by weight of di-(2-butoxyethyl)-adipate (DBEA) added to extruder 2, based on the amount of resin, and 10% by weight of di-(2-butoxyethyl)-adipate (DBEA) added to extruder 1, based on the amount of resin.

[0083] The formulation of Example 1.2 contains 20% by weight of di-(2-butoxyethyl)-adipate ester (DBEA) to be added to extruder 2, based on the amount of resin, and 10% by weight of di-(2-butoxyethyl)-adipate ester (DBEA) to be added to extruder 1, based on the amount of resin.

[0084] The formulation of Example 2.1 contains 27.5% by weight of 3G8 added to extruder 1 based on the amount of resin, and 15% by weight of di-(2-butoxyethyl)-adipate ester (DBEA) added to extruder 2 based on the amount of resin.

[0085] The formulation of Example 2.2 contains 27.5% by weight of 3G8 added to extruder 1 based on the amount of resin, and 20% by weight of di-(2-butoxyethyl)-adipate ester (DBEA) added to extruder 2 based on the amount of resin.

[0086] The formulation of Example 3.1 contains 37.5% by weight of 3G8, based on the amount of resin, to be added to the extruder 2.

[0087] The formulation of Example 3.2 contains 37.5% by weight of 3G8 added to extruder 2 based on the amount of resin, and 10% by weight of di-(2-butoxyethyl)-adipate (DBEA) added to extruder 1 based on the amount of resin.

[0088] The formulation of Example 5.1 contains 10% by weight of di-(2-butoxyethyl)-adipate (DBEA) to be added to extruder 2, based on the amount of resin.

[0089] The formulation of Example 5.2 contains 15% by weight of di-(2-butoxyethyl)-adipate (DBEA) to be added to extruder 2, based on the amount of resin.

[0090] [Materials used according to the present invention] <Ethylene vinyl acetal (ACEV1) of layer A and layer C> 100 parts by weight of an ethylene vinyl alcohol copolymer (saponification degree: 99) containing 44 mol% of ethylene units synthesized according to the production method described in Japanese Patent Application Laid-Open No. 2016-28139 are dispersed in 315 parts by weight of 1-propanol, and the solution temperature is raised to 60°C while stirring. Then, 40 parts by weight of 1M hydrochloric acid is added, and then 16.7 parts by weight of n-butyl aldehyde is added while maintaining the temperature at 60°C. As the reaction proceeds, the ethylene vinyl alcohol copolymer dissolves, and the reaction mixture becomes a homogeneous solution. After 36 hours, 6.4 parts by weight of sodium hydrogen carbonate is added to stop the reaction. After adding 500 parts by weight of 1-propanol to the reaction solution to make it uniform, it is added dropwise to 2000 parts by weight of water to precipitate the resin. Then, the operations of filtration and washing with water are repeated three times, and the obtained solid is vacuum dried at 60°C for 8 hours. The ethylene vinyl acetal thus obtained has an ethylene unit content of 44 mol% and an acetalization degree of 31 mol%.

[0091] <Ethylene vinyl acetal (ACEV2) of layer B> 100 parts by weight of an ethylene vinyl alcohol copolymer (saponification degree: 99) containing 48 mol% of ethylene units synthesized according to the production method described in Japanese Patent Application Laid-Open No. 2016-28139 are dispersed in 315 parts by weight of 1-propanol, and the solution temperature is raised to 60°C while stirring. Then, 40 parts by weight of 1M hydrochloric acid is added, and further 34.2 parts by weight of n-butyl aldehyde is added while maintaining the temperature at 60°C. As the reaction proceeds, the ethylene vinyl alcohol copolymer dissolves, and the reaction mixture becomes a homogeneous solution. After 36 hours, 6.4 parts by weight of sodium hydrogen carbonate is added to stop the reaction. After adding 500 parts by weight of 1-propanol to the reaction solution to make it uniform, it is added dropwise to 2000 parts by weight of water to precipitate the resin. Then, the operations of filtration and washing with water are repeated three times, and the obtained solid is vacuum dried at 60°C for 8 hours.

[0092] <Polyvinyl butyral layer A (PVB1)> Polyvinyl alcohol and 100 parts by weight of Kuraray Poval® 28-99 (a commercially available product from Kuraray Europe GmbH) were dissolved in 1075 parts by weight of water while heating to 90°C. At 40°C, 57.9 parts by weight of n-butyraldehyde were added, and 100 parts by weight of 20% hydrochloric acid were added while stirring at 12°C. After polyvinyl butyral (PVB) precipitated, the mixture was heated to 71°C and stirred at this temperature for 2 hours. After cooling to room temperature, the PVB was separated, washed with water until neutral, and dried. PVB with a polyvinyl alcohol content of 19.0% by weight (27.5 mol%) and a polyvinyl acetate content of 1.3% by weight (1 mol%) was obtained.

[0093] <Polyvinyl butyral layer B (PVB2)> Polyvinyl alcohol with a degree of hydrolysis of 92.5 mol%, 100 parts by weight of Kuraray Poval (registered trademark) 50-92 (commercial product of Kuraray Europe GmbH), and 68 parts by weight of n-butyraldehyde were used. A PVB with a polyvinyl alcohol content of 12.0% by weight (18.3 mol%) and a polyvinyl acetate content of 9.6% by weight (7.5 mol%) was obtained.

[0094] <tpe1> This is a hydrogenated polystyrene-polyisoprene-polystyrene triblock copolymer thermoplastic elastomer with 75% 1,2- and 3,4-bond content. It has a hard block / soft block ratio [Mw(Al) / Mw(A2)] of 1.00, a glass transition temperature of -15°C, a styrene content of 21% by mass, a hydrogenation rate of 84%, and a weight-average molecular weight of 120,000. It is commercially available from Kuraray Co., Ltd. (Tokyo, Japan) as "Hybler (trademark) H7125".

[0095] <Ionomer> The ionomer used as an intermediate layer, manufactured by Kuraray America, Inc. (Wilmington, DE, USA) under the trademark "SENTRY GLAS® XTRA®," is produced from CI2, as described in U.S. Patent Application Publication No. 20190030863.

[0096] [Fabrication of laminates] A test laminate with dimensions of 30 × 30 cm is obtained by combining transparent glass (Planilux® 2.1 mm, washed with deionized water < 5 μS in a plate glass washing machine) with an interlayer having layer A and layer B that are always in contact with the glass.

[0097] Various sandwich-like materials are passed through a commercially available plate glass lamination nipper line to create pre-laminated structures. Lamination is performed using an autoclave under standard conditions (140°C, 12 bar, 90 minutes including a 30-minute holding time).

[0098] [measurement] To quantify the coupling and damping properties of the novel interlayer of the present invention, an impedance test in accordance with ISO 16940 (as of December 2008) is performed on a 25 × 300 mm laminated beam cut from the laminate. Here, the loss factor (LF) is directly related to damping, while the resonant frequency (f) is related to coupling due to bending stiffness, which can be calculated from the resonant frequency. Because plasticizers are redistributed between different layers of the multilayer film after a "thermal shock" such as a typical autoclave process for safety glass laminates, the impedance characteristics are evaluated precisely at 20°C six weeks after the laminate has been equilibrated. Preferred embodiments of the present invention include the following: [1] A sound-attenuating interlayer for laminated glass comprising at least two individual membranes, wherein the first individual membrane (A) comprises ethylene vinyl acetal. [2] The sound-attenuating interlayer according to [1], wherein the ethylene vinyl acetal comprises ethylene units in the range of 25 to 60 mol%. [3] The sound-attenuating interlayer according to [1] or [2], comprising at least three individual membranes, wherein the first individual membrane (A) and the third individual membrane (C) constitute the outer layer and the second individual membrane (B) constitutes the inner layer. [4] The sound-attenuating interlayer according to [3], wherein the first individual membrane (A) and the third individual membrane (C) are ethylene vinyl acetal. [5] The sound-attenuating interlayer according to [4], wherein the first individual membrane (A), the second individual membrane (B), and the third individual membrane (C) each contain ethylene vinyl acetal. [6] The sound-attenuating interlayer according to [3], wherein the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and the second individual membrane (B) contains a thermoplastic elastomer. [7] The sound-attenuating interlayer according to [3], wherein the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and the second individual membrane (B) contains polyvinyl acetal. [8] The second individual membrane (B) comprises ethylene vinyl acetal, the sound-attenuating interlayer as described in [3]. [9] The sound-attenuating interlayer according to [8], wherein the first individual membrane (A) and the third individual membrane (C) are polyvinyl acetal.

[10] The sound-attenuating interlayer according to [3], wherein the first individual membrane (A) and the third individual membrane (C) comprise an ionomer.

[11] The sound-attenuating interlayer according to any one of [1] to

[10] , wherein at least one of the individual membranes (A), (B), or (C) is wedge-shaped.

[12] The sound-attenuating interlayer according to

[11] , wherein the individual membranes (A), (B), and (C) are wedge-shaped.

[13] A sound-attenuating interlayer according to any one of the individual membranes (A), (B), and (C), wherein at least one of them contains a plasticizer in an amount of 10 to 50% by weight.

[14] A sound-attenuating interlayer described in any one of [1] to

[13] , with a loss factor value greater than 0.1 when measured in accordance with ISO16940 (as of December 2008).

[15] Laminated glass comprising two glass plates combined with a sound-attenuating interlayer as described in any one of items [1] to

[14] .

Claims

1. An interlayer for laminated glass comprising at least two individual films, wherein the first individual film (A) comprises ethylene vinyl acetal. The ethylene vinyl acetal contains ethylene units in the range of 25 to 60 mol%, the degree of acetalization of the ethylene vinyl acetal is greater than 10 mol% and less than or equal to 38 mol%, and the degree of saponification of the acetate group is 95 mol% or more. The loss factor value measured in accordance with ISO 16940 (as of December 2008) is greater than 0.

1. Interlayer.

2. The interlayer according to claim 1, comprising at least three individual membranes, wherein the first individual membrane (A) and the third individual membrane (C) constitute an outer layer, and the second individual membrane (B) constitutes an inner layer.

3. The interlayer according to claim 2, wherein the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal.

4. The interlayer according to claim 3, wherein the first individual membrane (A), the second individual membrane (B), and the third individual membrane (C) each contain ethylene vinyl acetal.

5. The interlayer according to claim 2, wherein the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and the second individual membrane (B) contains a thermoplastic elastomer.

6. The interlayer according to claim 2, wherein the first individual membrane (A) and the third individual membrane (C) contain ethylene vinyl acetal, and the second individual membrane (B) contains polyvinyl acetal.

7. The interlayer according to claim 2, wherein the second individual membrane (B) comprises ethylene vinyl acetal.

8. The interlayer according to claim 7, wherein the first individual film (A) and the third individual film (C) contain polyvinyl acetal.

9. The interlayer according to claim 2, wherein the first individual membrane (A) and the third individual membrane (C) contain an ionomer.

10. An interlayer according to any one of claims 1 to 9, wherein at least one of the individual membranes (A), (B), or (C) is wedge-shaped.

11. The interlayer according to claim 10, wherein the individual films (A), (B), and (C) are wedge-shaped.

12. The interlayer according to any one of claims 1 to 11, wherein at least one of the individual films (A), (B), and (C) contains a plasticizer in an amount of 10 to 50% by weight.

13. Laminated glass comprising two glass plates joined together by an interlayer as described in any one of claims 1 to 12.

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