Sound-insulating laminated glazing comprising intermediate layer consisting of two outer layers based on ethylene-carboxylic acid copolymers and adhesive inner layer based on latex, plasticizer and tackifier

Abstract

The invention relates to a laminated glazing comprising an inner glass sheet (1) and an outer glass sheet (2), each comprising an inner face and an outer face, and an intermediate layer (3) between the inner faces of the two glass sheets, characterized in that the intermediate layer comprises:-at least two viscoelastic outer layers (4) and (5) having a thickness of 0.1 mm to 0.8 mm, -two outer layers (4), (5), each of which is in direct contact with one of the two glass sheets and is formed from a material comprising at least one ionomer based on ethylene and a carboxylic acid copolymer, and-a viscoelastic damping adhesive inner layer (6) arranged between the two outer layers (4) and (5), said viscoelastic damping adhesive layer having a thickness of 15 [mu] m to 25 [mu] m, and formed from a material comprising at least one acrylic polymer, at least one tackifier and at least one plasticizer. The invention also relates to a side window or a windshield of a vehicle comprising the laminated glazing as described above, and a method for manufacturing the laminated glazing as described above.

Description

[0001] The present invention relates to a laminated glazing having good mechanical properties for damping vibrations and / or improving the transmission loss of noise, in particular of airborne origin, in particular in the audible frequency decade of 1 kHz to 10 kHz at room temperature, and to a method for producing the laminated glazing. In particular, the laminated glazing may be a side window or a windshield of a vehicle.

[0002] It is known to use tempered monolithic glazing for the sound insulation of vehicles or buildings, and more particularly for the side windows of motor vehicles. However, such glazings exhibit a significant transmission of airborne noise caused by air flow turbulence over the glazing. Furthermore, in the case of such tempered monolithic glazings, an improvement in the sound insulation is usually accompanied by an increase in the glass thickness; this is a particular problem in the automotive glazing sector due to today's demand for lighter vehicles.

[0003] To solve this problem, thin glazing can be laminated with a viscoelastic interlayer consisting of a material based on polyvinyl butyral (PVB), better known as acoustic PVB. To this end, document EP2608958 describes a laminated glazing with vibration-damping properties, consisting of a first glass sheet and a second glass sheet of low thickness, with a viscoelastic interlayer in between. The interlayer is a three-layer interlayer, which comprises two PVB layers (also called "outer layers" or "skins") assembled with the aid of a PVB layer (also called "inner layer" or "core") comprising a plasticizer. In this type of interlayer, the inner layer has higher vibration damping properties than the two outer layers. In addition, such laminated glazing provides higher sound insulation performance than tempered monolithic glazing for the same glass thickness. However, such laminated glazing has a lower mechanical stiffness than tempered monolithic glazing.

[0004] In practice, improving the mechanical strength of glazing units for buildings or motor vehicles, combined with reduced glass thickness and good sound insulation are generally incompatible with one another.

[0005] The Applicant has therefore sought to provide thin laminated glazing having improved sound insulation, in particular for airborne sound in the frequency decade between 1 kHz and 10 kHz at room temperature (or an increased sound attenuation), and good mechanical properties, such as good mechanical strength (e.g. stiffness, shear stress, etc.).

[0006] The Applicant has thus developed a laminated glazing comprising an inner pane (1) and an outer pane (2), each comprising an inner face and an outer face, and an intermediate layer (3) between the inner faces of the two panes, characterised in that the intermediate layer comprises:

[0007] at least two viscoelastic outer layers (4) and (5) having a thickness ranging from 0.1 mm to 0.8 mm, each of the two outer layers being in direct contact with one of the two glass sheets and being formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymers, and

[0008] - a viscoelastic damping adhesive inner layer (6) arranged between the two outer layers (4) and (5), the viscoelastic damping adhesive layer having a thickness of 15 to 25 μm and being formed from a material comprising at least one acrylic polymer, at least one tackifier and at least one plasticizer.

[0009] Figure 1 -[ Figure 1 ] schematically shows a detail of a cross section of a laminated glazing according to one embodiment of the invention.

[0010] In fact, the inventors have surprisingly found that the following combination in the interlayer allows to obtain laminated glazings having improved sound insulation properties, more particularly high airborne sound attenuation properties, and good mechanical properties, more particularly high mechanical strength: two outer layers formed from a specific material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm, and an inner layer having a specific thickness ranging from 15 μm to 25 μm and formed from a specific acrylic polymer-based material, a tackifier and a plasticizer (as defined in the present application).

[0011] This improvement in airborne sound insulation of the glazing obtained according to the invention is due to the loss factor tan δ (determined by dynamic mechanical analysis) of the three-layer interlayer being greater than or equal to 2, preferably greater than or equal to 3, over a frequency decade of 1 Hz to 10 kHz, preferably over a frequency interval of 1 kHz to 10 kHz, for a temperature range of 0°C to 40°C, preferably 10°C to 30°C, more preferably 15°C to 25°C and even more preferably at a temperature close to or equal to 20°C.

[0012] Thus, the inventors have demonstrated that the embodiment of the interlayer further enhances the sound insulation performance of the glazing with which it is provided, said interlayer having a high loss factor tan δ and which therefore comprises:

[0013] - two outer layers based on ethylene-carboxylic acid copolymers, the thickness of which ranges from 0.1 mm to 0.8 mm, preferably from 0.15 mm to 0.5 mm, preferably from 0.2 mm to 0.4 mm, and more preferably equal to 0.38 mm, and

[0014] - An inner layer formed of a specific material based on acrylic polymer, a tackifier and a plasticizer and having a specific thickness of 15 μm to 25 μm.

[0015] The loss factor tan δ of a material corresponds to the ratio of the energy dissipated in the form of heat to the energy of elastic deformation. It therefore corresponds to a technical characteristic specific to the properties of the material and translates the ability of the material to dissipate energy, in particular sound waves. The higher the loss factor, the greater the energy dissipated, and therefore the greater the material's vibration damping effect. The loss factor tan δ varies according to the temperature and frequency of the incident wave. For a given frequency, the loss factor reaches its maximum value at a temperature called the glass transition temperature determined by dynamic mechanical analysis. The loss factor tan δ can be estimated using a rheometer or any other suitable known device. A rheometer is a device that enables a sample of a material to be subjected to deformation stresses under precise temperature and frequency conditions, and thereby obtains and processes a set of rheological quantities that characterize the material. More specifically, the loss factor is measured using a rotational rheometer in oscillation mode, where the sample is subjected to a sinusoidal stress of an angular velocity ω of 1 to 1000 rad / s in a temperature range of -100°C to 100°C (with increments of 5°C). The rheometer used by the applicant is the MCR 302 model from Anton Paar.

[0016] According to the invention, the laminated glazing consists of a first inner glass sheet (1) and a second outer glass sheet (2), with an intermediate layer (3) arranged therebetween.

[0017] According to the present invention, "inner glass sheet" refers to the glass sheet facing the interior of a vehicle or a building. "Outer glass sheet" in this application refers to the glass sheet facing the external environment.

[0018] Each glass sheet has an inner face and an outer face. Between the inner faces of the two glass sheets (1, 2) is an intermediate layer (3).

[0019] The inner and outer panes (1, 2) are preferably made of soda-lime glass, as is customary for windows. However, the panes can also be made of other types of glass, such as quartz glass, borosilicate glass or aluminosilicate glass, or of rigid transparent plastics, such as polycarbonate or polymethyl methacrylate. The thickness of the inner and outer panes can vary and thus be adapted to the respective requirements. The inner and / or outer panes preferably have a thickness of 0.5 mm to 12 mm and preferably 1.1 mm to 3 mm.

[0020] According to a preferred embodiment, the inner and / or outer glass sheet comprises at least one coating. This (these) coating is intended to give the glass substrate the following properties: optical properties (mirror layer or anti-reflection layer), thermal properties (low-emissivity layer, solar control layer or anti-solar layer) or electrical properties (transparent conductive layer, antistatic layer). The inner and / or outer glass sheet may also comprise other types of coatings, such as non-stick coatings, scratch-resistant coatings or photocatalytic coatings.

[0021] Another possibility is that the inner and / or outer panes can be tinted, thereby featuring one or more metal oxide coatings, providing various thermal or aesthetic functions to the glazing. Furthermore, the inner and / or outer panes can be thermally or chemically tempered (such as the IOX or Gorilla Glass types sold by the company Corning) and / or have electrochromic functions to control and vary the light transmission (TL) of the glazing.

[0022] The intermediate layer (3) is arranged between the first and second glass sheets, that is, between the inner glass sheet (1) and the outer glass sheet (2) as defined above, and more precisely between the inner faces of the two glass sheets (1, 2). The intermediate layer according to the invention comprises at least two viscoelastic outer layers (4) and (5), each of which is in direct contact with one of the two glass sheets and has a thickness ranging from 0.1 mm to 0.8 mm, both outer layers being formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymers, said outer layers also being called "skin layers". The outer layers (4) and (5) are assembled by means of a viscoelastic damping adhesive inner layer (6), defined hereinafter.

[0023] The two viscoelastic outer layers (4) and (5) according to the invention have a thickness comprised between 0.1 mm and 0.8 mm, preferably between 0.15 mm and 0.5 mm, preferably between 0.2 mm and 0.4 mm, and more preferably this thickness is equal to 0.38 mm.

[0024] The two outer layers ensure in particular that the viscoelastic intermediate layer sandwiched between the two glass sheets has a sufficiently high shear modulus (G'); in other words, that the glazing has sufficient stiffness. The shear modulus G' is related - in particular for isotropic materials - to the Young's modulus E' by the relation G'=E' / 2(1+ν), where ν is the Poisson's factor of the material.

[0025] Each of the two outer layers (4) and (5) is in direct contact with one of the two glass sheets (1) or (2). The two outer layers are formed of a material comprising at least one ionomer based on an ethylene-carboxylic acid copolymer. Preferably, the ionomer is a copolymer comprising at least one ethylene monomer and at least one α-β-unsaturated carboxylic acid monomer, and 1% to 100% of the acid groups of the copolymer are neutralized into carboxylates comprising carboxylate ions and metal counterions. The metal counterions may consist essentially of zinc ions. Advantageously, 15% to 45% of the acid groups of the copolymer are neutralized, and even more advantageously 25% to 40% are neutralized.

[0026] And more particularly, the copolymer has from 12% to 30% of carboxylic acid monomers selected from α-β-unsaturated acids having from 3 to 8 carbon atoms. Even more particularly, the copolymer has from 17% to 23% of carboxylic acid monomers.

[0027] The carboxylic acid that can be used as the monomer for the copolymer described above is selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, monomethyl maleate and mixtures thereof. Functional equivalents of carboxylic acids known to those skilled in the art can also be used, such as carboxylates, anhydrides, esters, acyl halides, amides, nitriles and similar compounds that can be converted into carboxylic acids or acid salts by hydrolysis.

[0028] In the present invention, for example, those described in the following patent applications can be used as ethylene-carboxylic acid-based ionomer resins: WO 2004 / 011755, WO 2006 / 057771 and WO 2007 / 064794. In particular, the so-called The layer sold by the company Dupont de Nemours serves as the viscoelastic outer layer.

[0029] According to the present invention, the viscoelastic damping adhesive inner layer (6) is arranged between the two outer layers (4) and (5) and has a thickness of 15 μm to 25 μm, preferably the thickness is equal to 25 μm, and the inner layer is formed by a material comprising at least one acrylic polymer, at least one tackifier and at least one plasticizer.

[0030] The inventors surprisingly found that the thickness of the viscoelastic damping adhesive inner layer (6) arranged between the two outer layers (4) and (5) must be between 15 μm and 25 μm in order to achieve better sound insulation of the laminated glazing.

[0031] The inner layer (6) according to the invention thus serves to bond the two outer layers (4) and (5) of the intermediate layer (3) together and, after drying and calendering, to ensure the structural adhesion of the two glass sheets in the laminated glazing, and subsequently serves to dampen vibrations and / or improve the transmission losses of noise, in particular of airborne origin, over a frequency decade of 1 kHz to 10 kHz at room temperature. Furthermore, the specific thickness of the inner layer ensures that the laminated glazing according to the invention has good acoustic properties.

[0032] Preferably, the inner layer (6) is located in the center of the intermediate layer (3), which is itself arranged between the first and second glass sheets (1, 2).

[0033] The material of the viscoelastic damping adhesive inner layer may have a glass transition temperature of -55°C to 10°C (inclusive), in particular -45°C to +5°C and preferably -30°C to -5°C.

[0034] According to the present invention, the glass transition temperature (Tg) of the viscoelastic damping adhesive inner layer can be measured by differential scanning calorimetry (DSC). The glass transition temperature can be determined using the midpoint method for differential scanning calorimetry as described in ASTM-D-3418. The measuring device used by the applicant is the Discovery DSC model from TA Instruments.

[0035] Preferably, the glass transition temperature Tg is determined by dynamic mechanical analysis (DMA) or dynamic mechanical spectroscopy. The value of Tg is determined by plotting an isofrequency curve of the loss factor as a function of the material temperature. The temperature at which the loss factor value is maximum is equal to the glass transition temperature Tg. The glass transition temperature depends on the excitation frequency of the material. In the present application, "glass transition temperature" refers to the glass transition temperature measured by DMA at a frequency of 1 Hz.

[0036] As defined previously, according to the invention, the viscoelastic damping inner layer (6) is formed from a material comprising at least one acrylic polymer, at least one tackifier and at least one plasticizer.

[0037] The acrylic polymer can be selected from methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, amyl acrylate, amyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, octyl methacrylate, isooctyl acrylate, isooctyl methacrylate, nonyl acrylate, methyl methacrylate, The monomers are nonyl acrylate, isononyl methacrylate, isobornyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, vinyl formate, vinyl acetate, vinyl propionate, 2-hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid, styrene and acrylonitrile.

[0038] The acrylic polymer may be a copolymer formed from at least two monomers selected from the previously defined monomers.

[0039] Preferably, the inner layer may comprise two different acrylic polymers. Preferably, one of the two polymers is 2-ethylhexyl acrylate (2-EHA) and the other of the two polymers is butyl acrylate (BA). The mass ratio of 2-ethylhexyl acrylate (2-EHA) to butyl acrylate (BA) may be 2 to 4, and preferably equal to 3.

[0040] Other commercial latexes containing acrylic polymers may be used to form the inner layer (6). For example, Encor 4028, Encor 4517 or A&B 75070 latex.

[0041] The material may include another polymer other than an acrylic polymer. Such another polymer may be formed from at least one monomer selected from styrene and methyl methacrylate.

[0042] The material may comprise a first acrylic polymer having a first glass transition temperature Tg1 and a second acrylic or non-acrylic polymer having a second glass transition temperature Tg2 greater than Tg1. The difference between the second glass transition temperature Tg2 and the first glass transition temperature Tg1 is preferably greater than 10°C, and preferably greater than 20°C. Thus, the glass transition temperature of the material may be increased for the glass transition temperature of the material obtained using only the first acrylic polymer. In fact, the glass transition temperature obtained using only the first acrylic polymer may be too low to have the maximum damping of the material in the audible frequency range.

[0043] The polymer may form an interpenetrating polymer network (RIP).Thus, in the present invention, a polymer system of the interpenetrating polymer network (RIP) type may be used to form the core of the three-layer intermediate layer (3).

[0044] The applicant specifically proposes the use of latex, i.e. an aqueous emulsion of polymer particles containing IPN, to form the inner layer of the three-layer intermediate layer as defined in the present application. In the present application, "latex" is understood to refer to a dispersion of polymer particles in water or in an aqueous solvent. The latex may contain polymer particles having a core-shell structure. The core may be formed by an interpenetrating polymer network (IPN) having a glass transition temperature (Tg) of -50°C to -30°C, preferably -45°C to -35°C, and the shell may be formed by a polymer having a glass transition temperature low enough to allow the particles to coalesce after drying. The glass transition temperature of the shell may be lower than the glass transition temperature of the core, and may preferably be less than -50°C, and more preferably less than -60°C. The IPN thus comprises a first crosslinked polymer and a second polymer, which may or may not be crosslinked. In a preferred embodiment of the present invention, the second polymer is non-crosslinked. In this case, the IPN is a so-called "semi-interpenetrating polymer" network (semi-IPN). The second polymer may be linear or branched.

[0045] In particular, the mass fraction of the acrylic polymer in the viscoelastic damping adhesive inner layer (6) of the material is from 0.21 to 0.62, especially from 0.21 to 0.51, and preferably from 0.21 to 0.35.

[0046] In the present application, the “mass fraction” of a first element in a second element is understood to mean the ratio of the mass of the first element to the mass of the second element.

[0047] The addition of a tackifier and / or a plasticizer to the at least one acrylic polymer provides a means of adhesion between the two viscoelastic outer layers.

[0048] The tackifier may be selected from natural tackifying resins, especially rosin and terpenes, and synthetic tackifying resins, such as aliphatic or aromatic resins derived from petroleum. The tackifier may comprise a hydrogenated resin, and preferably a hydrogenated rosin resin. The hydrogenated resin may comprise a glycerol ester of a wood resin, preferably a rosin acid. The hydrogenated resin may comprise a hydrogenated rosin ester (e.g., a rosin ester under the trade name KE-311 or KE-100 or FTE019 or FTE020 resin).

[0049] In particular, the mass fraction of the tackifier in the viscoelastic damping adhesive inner layer (6) is 0.17 to 0.60, especially 0.22 to 0.35, and preferably 0.22 to 0.26.

[0050] According to the invention, the plasticizer allows the rheological properties of the composition of the viscoelastic damping adhesive inner layer to be optimized to obtain the best acoustic performance for glazing. The plasticizer may contain at least one element selected from the group consisting of citric acid esters, adipates, ethylene glycol and triethylene glycol derivatives. The citric acid ester may be acetyl tributyl citrate. The adipates may be triethylene glycol bis(2-ethylhexanoate) (e.g. Sold under the name WVC 3800).

[0051] In particular, the mass fraction of the plasticizer in the viscoelastic damping adhesive inner layer (6) is from 0.07 to 0.43, especially from 0.12 to 0.31, and preferably from 0.16 to 0.26.

[0052] Thus, advantageously, the material has a mass fraction of acrylic polymer in the viscoelastic damping adhesive inner layer (6) of 0.21 to 0.62, a mass fraction of plasticizer in the inner layer (6) of 0.07 to 0.43 and a mass fraction of tackifier in the inner layer (6) of 0.17 to 0.60.

[0053] Advantageously, the material has a mass fraction of acrylic polymer in the viscoelastic damping adhesive inner layer (6) of 0.21 to 0.51, a mass fraction of plasticizer in the inner layer (6) of 0.12 to 0.31 and a mass fraction of tackifier in the inner layer (6) of 0.22 to 0.35.

[0054] Advantageously, the material has a mass fraction of 0.21 to 0.35 of acrylic polymer in the viscoelastic damping adhesive inner layer (6), a mass fraction of 0.16 to 0.26 of plasticizer in the inner layer (6) and a mass fraction of 0.22 to 0.26 of tackifier in the inner layer (6).

[0055] Advantageously, the material has a mass fraction of acrylic polymer in the viscoelastic damping adhesive inner layer (6) of 0.21 to 0.62, a mass fraction of plasticizer in the inner layer (6) of 0.12 to 0.31 and a mass fraction of tackifier in the inner layer (6) of 0.22 to 0.35.

[0056] Advantageously, the material has a mass fraction of acrylic polymer in the viscoelastic damping adhesive inner layer (6) of 0.21 to 0.62, a mass fraction of plasticizer in the inner layer (6) of 0.16 to 0.26 and a mass fraction of tackifier in the inner layer (6) of 0.22 to 0.26.

[0057] According to a preferred embodiment of the present invention, the intermediate layer (3) further comprises two films (7) and (8) made of a material selected from poly(ethylene vinyl acetate) (EVA) and poly(ethylene terephthalate) (PET) and mixtures thereof, each of the two films being arranged between the viscoelastic damping adhesive inner layer (6) and one of the two viscoelastic outer layers (4) or (5). Thus, preferably, the inner layer (6) is located in the center of the intermediate layer (3), which itself is arranged between the first glass sheet and the second glass sheet (1, 2). And advantageously, the two films (7) and (8) are in direct contact with the viscoelastic damping adhesive inner layer (6). And even more advantageously, the film (7) is also in direct contact with the viscoelastic outer layer (4), and the film (8) is also in direct contact with the viscoelastic outer layer (5). The thickness of each of the two films is preferably from 6 μm to 200 μm, and more preferably from 12 μm to 50 μm. Thus, preferably, the intermediate layer (3) consists of five layers, namely an adhesive inner layer (6), films (7) and (8) and viscoelastic outer layers (4) and (5).

[0058] The two films (7) and (8) have the advantage of preventing components of the inner layer from entering the outer layer and thus avoiding any chemical incompatibility between components of the inner layer and components of the outer layer of the intermediate layer.

[0059] Figure 2 -[ Figure 2 ] schematically shows a detail of a cross section of a laminated glazing according to a preferred embodiment of the invention as described hereinbefore.

[0060] Preferably, the layer (or film) between the inner sheet of glass (1) and the inner layer (6) and the layer between said inner layer (6) and the outer sheet of glass (2) are identical; in other words, they have the same chemical nature and thickness.

[0061] The invention also relates to a side window or windshield of a vehicle comprising a laminated glazing as described above.

[0062] The present invention also relates to a method for producing a laminated glazing as described above, comprising the following steps:

[0063] a) providing an inner glass sheet (1) and an outer glass sheet (2),

[0064] b) Arranging an intermediate layer (3) between the inner faces of the two glass sheets (1, 2), the intermediate layer (3) comprising:

[0065] a first viscoelastic layer (4) formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm,

[0066] a viscoelastic damping adhesive layer (6) formed of a material comprising at least one acrylic polymer, at least one tackifier, and having a thickness of 15 μm to 25 μm, and

[0067] a second viscoelastic layer (5) formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm,

[0068] c) assembling the two glass sheets (1, 2) and the interlayer (3) by lamination to form a laminated glazing, and

[0069] d) Degassing by autoclaving the laminated glazing.

[0070] According to a preferred embodiment, the intermediate layer (3) is manufactured according to a method comprising the following steps:

[0071] - providing a first sheet made of a material comprising at least one ionomer based on an ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm,

[0072] - depositing a liquid composition on one side of the first ethylene-carboxylic acid copolymer-based ionomer sheet, the liquid composition comprising a latex, a tackifier and a plasticizer, the latex comprising an emulsion comprising a continuous aqueous phase and a dispersed phase, the dispersed phase comprising at least one acrylic polymer,

[0073] - drying the composition to form a viscoelastic damping adhesive layer having a thickness of 15 μm to 25 μm,

[0074] - Applying on said adhesive layer thus formed a second sheet made of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm.

[0075] The liquid composition may be a dilution of latex, tackifier and plasticizer in an aqueous phase.

[0076] The step of depositing a liquid composition comprising latex, a tackifier and a plasticizer on a first sheet made of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness of 0.1 mm to 0.8 mm can be carried out by a known roll-to-roll liquid deposition method, more precisely by nip-fed reverse roll liquid deposition.

[0077] Furthermore, the drying step of the composition is preferably carried out continuously at room temperature and / or in an oven at a temperature ranging from 40° C. to 120° C., preferably from 60° C. to 100° C. Advantageously, this drying step is carried out at a reduced pressure ranging from 0.01 atm to 1 atm, preferably from 0.1 atm to 0.5 atm, ideally at a pressure equal to 0.25 atm.

[0078] Preferably, the intermediate layer (3) further comprises two films (7) and (8) made of a material selected from the group consisting of poly(ethylene vinyl acetate) (EVA) and poly(ethylene terephthalate) (PET) and mixtures thereof, each of the two films being arranged between the viscoelastic damping adhesive inner layer (6) and one of the two viscoelastic outer layers (4) or (5), and each of the two films being advantageously in direct contact with the viscoelastic damping adhesive inner layer and / or one of the two viscoelastic outer layers. In this particularly preferred embodiment, a liquid composition comprising latex, a tackifier and a plasticizer is subsequently deposited on one side of the first film, the first film being made of a material selected from the group consisting of poly(ethylene vinyl acetate) (EVA) and poly(ethylene terephthalate) (PET) and mixtures thereof.

[0079] The process parameters, such as the tension of the ethylene-carboxylic acid copolymer based sheet and the stability of the rollers and the feeding of the liquid composition through the slot, can be controlled in such a way that the three-layer interlayer according to the invention does not have any corrugation defects.

[0080] The invention also relates to the use of a laminated glazing as described above as a side window or windshield of a motor vehicle or as a window of a building for damping vibrations in the audible frequency decade of 1 kHz to 10 kHz at room temperature and / or for improving the transmission loss of noise, which is particularly of airborne origin. In the case of the use of the glazing unit according to the invention as a windshield, it naturally meets all the conditions of United Nations Regulation 43 (called Regulation R43) for resistance to strong impacts in order to ensure its mechanical strength. Furthermore, the further glazing according to the invention has further improved soundproofing properties and good mechanical properties due to the specific choice of the interlayer (3) according to the invention.

[0081] Characterization of mechanical properties of laminated glazing

[0082] A laminated glazing according to the present invention is prepared, comprising:

[0083] - an inner glass sheet having a thickness of 2.1 mm,

[0084] - a viscoelastic outer layer having a thickness of 0.38 mm and comprising an ionomer based on ethylene-carboxylic acid copolymers,

[0085] - a viscoelastic damping adhesive inner layer having a thickness of 25 μm; said inner layer comprising two types of acrylic polymers formed from 2-ethylhexyl acrylate and isobutyl acrylate, and a tackifier such as TFE20-011 and plasticizer such as EP 123545K,

[0086] - a viscoelastic outer layer having a thickness of 0.38 mm and comprising an ionomer based on ethylene-carboxylic acid copolymers,

[0087] - An outer glass sheet having a thickness of 2.1 mm.

[0088] A laminated glazing according to the prior art (called "acoustic PVB") consists of two glass sheets with a thickness of 2.1 mm, laminated using a three-layer viscoelastic interlayer comprising two outer layers of PVB and an inner layer with a thickness equal to 0.10 mm comprising PVB and a plasticizer.

[0089] The laminated glazing described above was subsequently subjected to a shear modulus measurement (in Pa); this value characterizes the stiffness of the interlayer and therefore its acoustic performance.

[0090] The shear modulus is measured by DMTA using standard EN 16613 (in-plane shear method).

[0091] thus, Figure 3 -[ Figure 3 ] shows the shear modulus measurement results of the laminated glazing according to the present invention and the laminated glazing according to the prior art in the frequency range of 100 Hz to 10,000 Hz.

[0092] The curve formed by the continuous line shows the shear modulus of a laminated glazing according to the prior art, whereas the curve formed by the dashed line shows the shear modulus of a laminated glazing according to the invention.

[0093] Figure 3 The results reported in show that the laminated glazing according to the invention has better mechanical properties than laminated glazing according to the prior art, since the shear modulus of the interlayer according to the invention is approximately 100 times that obtained with the PVB interlayer of the prior art.

[0094] Acoustic Characterization of Laminated Glazing

[0095] In order to show the acoustic gain obtained between a laminated glazing according to the invention, a laminated glazing according to the prior art and another laminated glazing outside the invention (comparison), numerical simulations were performed. The acoustic model is based on the finite element method in order to reproduce the sound attenuation behavior according to NF EN ISO 10140.

[0096] thus, Figure 4 -[ Figure 4 ] shows the sound attenuation of laminated glazings of different configurations subjected to airborne noise generated according to standard NF EN 10140.

[0097] ●The curve formed by the solid line with triangles shows the sound attenuation of an assembled glass according to the prior art consisting of two glass sheets with a thickness of 2.1 mm, wherein the assembled glass is laminated using a three-layer viscoelastic interlayer, wherein the three-layer viscoelastic interlayer comprises two outer layers of PVB and an inner layer comprising PVB and a plasticizer with a thickness equal to 0.15 mm (called "acoustic PVB").

[0098] The curves formed by the dashed line with dots (called "SGP + 5 μm latex"), the solid line with dots (called "SGP + 10 μm latex"), the solid line with squares (called "SGP + 35 μm latex") and the solid line (called "SGP + 50 μm latex") respectively show the sound attenuation of a laminated glazing not covered by the present invention (comparative example). The laminated glazing consists of a viscoelastic damping adhesive inner layer comprising two types of acrylic polymers, the acrylic polymer being formed of 2-ethylhexyl acrylate and isobutyl acrylate, and comprising TFE20-011 as a tackifier and contains EP 123545K as plasticizer. The inner layers have thicknesses of 5 μm, 10 μm, 35 μm and 50 μm respectively and are located between two viscoelastic outer layers having a thickness of 0.38 mm and comprising an ionomer based on ethylene-carboxylic acid copolymer. The outer layers themselves are located between two glass sheets having a thickness equal to 2.1 mm.

[0099] The curves formed by the solid line with diamonds (called "SGP + 15 μm latex") and by the dashed line (called "SGP + 25 μm latex") respectively show the sound attenuation of a laminated glazing according to the invention. The laminated glazing consists of a viscoelastic damping adhesive inner layer comprising two types of acrylic polymers, the acrylic polymer being formed of 2-ethylhexyl acrylate and isobutyl acrylate, and comprising TFE20-011 as a tackifier and contains EP 123545K as plasticizer. The inner layers have a thickness of 15 μm and 25 μm respectively and are located between two viscoelastic outer layers having a thickness of 0.38 mm and comprising an ionomer based on ethylene-carboxylic acid copolymer. The outer layers are located between two glass sheets having a thickness equal to 2.1 mm.

[0100] Figure 4 The results reported in the study showed that:

[0101] - the laminated glazing according to the invention has an improvement of at least 2.7 dB in airborne sound attenuation at all frequencies from 5000 Hz to 10000 Hz at room temperature compared to laminated glazing according to the prior art (acoustic PVB), and

[0102] - Compared to laminated glazings whose viscoelastic damping adhesive inner layer arranged between two ethylene-carboxylic acid copolymer outer layers has a thickness outside the range of 15μm to 25μm, i.e. having a thickness equal to 5μm, 10μm, 35μm or 50μm, the laminated glazings according to the present invention have an improvement of at least 1.0 dB in airborne sound attenuation at all frequencies from 5000 Hz to 10,000 Hz at room temperature.

[0103] The laminated glazing according to the invention thus has good acoustic properties and good mechanical properties.

Claims

1. A laminated glazing comprising an inner glass sheet (1) and an outer glass sheet (2), wherein the inner glass sheet (1) and the outer glass sheet (2) each comprise an inner face and an outer face, and an intermediate layer (3) between the inner faces of the two glass sheets, characterized in that The middle layer comprises: at least two viscoelastic outer layers (4) and (5) having a thickness ranging from 0.1 mm to 0.8 mm, each of the two outer layers being in direct contact with one of the two glass sheets and being formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymers, and - a viscoelastic damping adhesive inner layer (6) arranged between the two outer layers (4) and (5), said viscoelastic damping adhesive layer having a thickness of 15 to 25 μm and being formed from a material comprising at least one acrylic polymer, at least one tackifier and at least one plasticizer.

2. The laminated glazing according to claim 1, wherein the ionomer is one or more copolymers comprising at least one ethylene monomer and at least one α-β-unsaturated carboxylic acid monomer, and 1% to 100% of the acid groups of the copolymer are neutralized to carboxylate salts comprising carboxylate ions and metal counterions.

3. Laminated glazing according to any of the preceding claims, wherein the material of the viscoelastic damping adhesive inner layer (6) has a glass transition temperature (Tg) of -55°C to 10°C.

4. Laminated glazing according to any of the preceding claims, wherein the material has a mass fraction of acrylic polymer in the viscoelastic damping adhesive inner layer (6) of 0.21 to 0.62, in particular 0.21 to 0.51 and preferably 0.21 to 0.

35.

5. The laminated glazing according to claim 1, wherein the material has a mass fraction of adhesion promoter in the viscoelastic damping adhesive inner layer (6) of 0.17 to 0.60, in particular 0.22 to 0.35 and preferably 0.22 to 0.

26.

6. Laminated glazing according to any one of the preceding claims, wherein the adhesion promoter comprises a hydrogenated resin, and preferably a hydrogenated rosin resin.

7. Laminated glazing according to any of the preceding claims, wherein the material has a mass fraction of plasticizer in the viscoelastic damping adhesive inner layer (6) of 0.07 to 0.43, in particular 0.12 to 0.31 and preferably 0.16 to 0.

26.

8. Laminated glazing according to any one of the preceding claims, wherein the acrylic polymer is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, amyl acrylate, amyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, octyl methacrylate, isooctyl acrylate, methacrylic acid, octyl acrylate, octyl methacrylate ...methacrylate, octyl acrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, octyl methacrylate, oct The monomers are isooctyl acrylate, nonyl acrylate, nonyl methacrylate, isononyl methacrylate, isobornyl methacrylate, decyl acrylate, decyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, vinyl formate, vinyl acetate, vinyl propionate, 2-hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid, styrene and acrylonitrile.

9. The laminated glazing according to claim 1 , wherein the material comprises a first acrylic polymer having a first glass transition temperature Tg1 and a second polymer having a second glass transition temperature Tg2 higher than Tg1, the difference between the second glass transition temperature Tg2 and the first glass transition temperature Tg1 being preferably greater than 10° C., and preferably greater than 20° C.

10. Laminated glazing according to any one of the preceding claims, wherein the inner pane (1) and the outer pane (2) have a thickness of 0.5 mm to 12 mm, preferably 1.1 mm to 3 mm.

11. Laminated glazing according to any one of the preceding claims, characterized in that The intermediate layer (3) further comprises two films (7) and (8) made of a material selected from poly(ethylene vinyl acetate) (EVA) and poly(ethylene terephthalate) (PET) and mixtures thereof, each of the two films being arranged between the viscoelastic damping adhesive inner layer (6) and one of the two viscoelastic outer layers (4) or (5).

12. The laminated glazing according to claim 11, characterized in that The two films (7) and (8) are in direct contact with the viscoelastic damping adhesive inner layer (6).

13. Laminated glazing according to claim 12, wherein each of the two films (7) and (8) has a thickness of 6 to 200 μm and preferably 12 to 50 μm.

14. A side window or windscreen of a vehicle comprising a laminated glazing according to any one of the preceding claims.

15. Use of a laminated glazing according to any one of claims 1 to 13 as a side window or windshield of a motor vehicle or as a building glazing.

16. A method for producing a laminated glazing according to any one of claims 1 to 13, comprising the following steps: a) providing an inner glass sheet (1) and an outer glass sheet (2), b) Arranging an intermediate layer (3) between the inner faces of the two glass sheets (1, 2), the intermediate layer (3) comprising: a first viscoelastic layer (4) formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm, a viscoelastic damping adhesive layer (6) formed of a material comprising at least one acrylic polymer, at least one tackifier, and having a thickness of 15 μm to 25 μm, and a second viscoelastic layer (5) formed of a material comprising at least one ionomer based on ethylene-carboxylic acid copolymer and having a thickness ranging from 0.1 mm to 0.8 mm, c) assembling the two glass sheets (1, 2) and the interlayer (3) by lamination to form a laminated glazing, and d) Degassing by autoclaving the laminated glazing.

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