Acoustically insulating laminated glazing comprising an interlayer made up of two external layers based on an ethylene-carboxylic acid copolymer and an adhesive internal layer based on latex, a plasticiser and a tackifier

Abstract

The present 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 comprising, between the inner faces of the two glass sheets, an interlayer (3), characterised in that the interlayer comprises: -at least two viscoelastic outer layers (4) and (5) having a thickness of between 0.1 mm and 0.8 mm, each of the two outer layers being in direct contact with one of the two glass sheets and being formed by a material comprising at least one ionomer based on ethylene and carboxylic acid copolymer, and - 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 between 15 µm and 25 µm and being formed by a material comprising at least one acrylic polymer, at least one tackifier and at least one plasticiser. The present invention also relates to a side window or windshield of a vehicle comprising a laminated glazing as described above, as well as to a method for manufacturing a laminated glazing as described above.

Description

[0001] DESCRIPTION

[0002] [TITLE OF THE INVENTION] Acoustically insulating laminated glazing comprising an interlayer composed of two external layers based on ethylene and carboxylic acid copolymer and an internal adhesive layer based on latex, plasticizing agent and tackifying agent

[0003] The present invention relates to a laminated glazing having good mechanical properties for damping vibrations and / or increasing the transmission loss of noise, in particular of airborne origin, in particular over the audible frequency decade between 1 kHz and 10 kHz at room temperature, as well as a method for manufacturing said laminated glazing. In particular, the laminated glazing may be a side window or a vehicle windshield.

[0004] It is known to use toughened monolithic glazing for the sound insulation of vehicles or buildings, and more particularly for the side glazing of motor vehicles. However, such glazing exhibits significant transmission of airborne noise caused by the turbulence of an air flow over said glazing. In addition, for these toughened monolithic glazings, the improvement in sound insulation is generally accompanied by an increase in the thickness of the glass; which poses a problem in particular in the field of automotive glazing due to the currently sought-after weight reduction of motor vehicles.

[0005] To solve this problem, thin glazings can be laminated using a viscoelastic interlayer composed of a material based on poly(vinyl butyral) (called PVB, from the English PolyVinyl Butyral), better known as acoustic PVB. To this end, document EP2608958 describes laminated glazings having vibration damping properties which are composed of a first glass sheet and a second glass sheet of thin thickness, between which is a viscoelastic interlayer. The interlayer is a three-layer interlayer comprising two layers of PVB, also called "outer layers" or "skins", assembled by means of a layer of PVB including plasticizing agents, also called "inner layer" or "core". In this type of interlayer, the inner layer has higher vibration damping properties than the two outer layers.In addition, such laminated glazing has higher acoustic insulation performance than monolithic tempered glazing, for equivalent glass thicknesses. However, such laminated glazing has lower mechanical rigidity than monolithic tempered glazing.

[0006] Indeed, improving the mechanical resistance of glazing for buildings or automobiles, combined with a reduction in glass thickness and good acoustic insulation, are generally not compatible with each other.

[0007] The Applicant therefore sought to provide laminated glazing, of low thickness, with improved acoustic insulation, in particular against airborne noise over the frequency decade between 1 kHz and 10 kHz, at room temperature (or an increase in acoustic attenuation) and good mechanical properties, such as good mechanical resistance (such as rigidity, shear stress, etc.).

[0008] The Applicant has thus developed 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 comprising, between the inner faces of the two glass sheets, an interlayer (3), characterized in that said interlayer comprises:

[0009] - at least two viscoelastic external layers (4) and (5) having a thickness of between 0.1 mm and 0.8 mm, each of the two external layers being in direct contact with one of the two glass sheets and formed by a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid, and

[0010] - an internal viscoelastic damping adhesive layer (6), arranged between the two external layers (4) and (5), said viscoelastic damping adhesive layer having a thickness of between 15 μm and 25 μm and being formed by a material comprising at least one acrylic polymer, at least one tackifying agent, and at least one plasticizing agent.

[0011] Figure 1 - [Fig. 1] schematically illustrates a detail of a section of laminated glazing according to one embodiment of the invention.

[0012] Indeed, it was surprisingly found by the inventors that the combination in the interlayer: of the two external layers formed by a particular material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid and having a thickness of between 0.1 mm and 0.8 mm with an internal layer having a specific thickness of between 15 μm and 25 μm and formed by a particular material based on acrylic polymer, tackifying agent and plasticizing agent (as defined in the present application), made it possible to obtain laminated glazing having improved acoustic insulation performance (more particularly high acoustic attenuation properties for airborne noise) and good mechanical properties (more particularly high mechanical strength).

[0013] This improvement in the acoustic insulation against airborne noise of the glazing obtained according to the invention is due to a loss factor: tan 5 (determined by dynamic mechanical analysis) of the three-layer interlayer whose value is greater than or equal to 2, preferably greater than or equal to 3, over the frequency decade between 1 Hz and 10 kHz, preferably over the frequency interval between 1 kHz and 10 kHz, for a temperature range between 0°C and 40°C, preferably between 10°C and 30°C, more preferably between 15°C and 25°C and even more preferably for a temperature close to or equal to 20°C.

[0014] Thus, the inventors have demonstrated that the implementation of an interlayer which has a high tan 5 loss factor and which therefore comprises:

[0015] - two external layers based on ethylene and carboxylic acid copolymer with a thickness of 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 equal to 0.38 mm, and

[0016] - an internal layer formed by a particular material based on acrylic polymer, tackifying agent and plasticizing agent and having a specific thickness of between 15 pm and 25 pm, makes it possible to further improve the acoustic insulation performance of the glazing which is equipped with it.

[0017] The loss factor tan 5 of a material corresponds to the ratio between the energy dissipated in the form of heat and the elastic deformation energy. It therefore corresponds to a technical characteristic specific to the nature of a material and reflects its capacity to dissipate energy, in particular acoustic waves. The higher the loss factor, the greater the dissipated energy, the more the material therefore plays its vibration damping function. This loss factor tan 5 varies according to the temperature and the 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. This loss factor tan 5 can be estimated using a rheometer or any other suitable known device.The rheometer is a device that allows a material sample to be subjected to deformation stresses under precise temperature and frequency conditions, and thus to obtain and process all the rheological quantities characterizing the material. More precisely, the loss factor is measured using a rotation rheometer in oscillation mode, where the sample is subjected to a sinusoidal stress for angular speeds co of 1 to 1000 rad / s in a temperature range from -100°C to 100°C with steps every 5°C. The rheometer used by the Applicant is the MCR 302 model from Anton Paar.

[0018] According to the invention, the laminated glazing is composed of a first inner glass sheet (1) and a second outer glass sheet (2), between which there is an interlayer (3).

[0019] According to the invention, the term "inner glass sheet" means a glass sheet facing the interior of the vehicle or building. An "outer glass sheet" designates in the present application a glass sheet facing the external environment.

[0020] Each glass sheet has an inner face and an outer face. Between the inner faces of the two glass sheets (1, 2) is the interlayer (3).

[0021] The inner and outer glass sheets (1, 2) are preferably made of soda-lime glass, as is customary for window panes. The glass sheets can, however, also be made of other types of glass, for example quartz glass, borosilicate glass or aluminosilicate glass, or of rigid transparent plastics, for example polycarbonate or polymethyl methacrylate. The thickness of the inner glass sheet and the outer glass sheet can vary and thus be adapted to various requirements. The inner glass sheet and / or the outer glass sheet preferably have a thickness of between 0.5 mm and 12 mm and preferably between 1.1 mm and 3 mm.

[0022] According to a preferred embodiment, the inner glass sheet and / or the outer glass sheet comprises at least one coating. This(these) coating(s) is(are) intended to give the glass substrate: optical properties (mirror or anti-reflective layers), thermal properties (low-emissive layers, solar control or anti-solar layers) or electrical properties (transparent conductive layers, anti-static layers). The inner glass sheet and / or the outer glass sheet may also comprise other types of coatings, such as non-stick coatings, anti-scratch coatings or photocatalytic coatings.

[0023] Another possibility is that the inner glass sheet and / or the outer glass sheet are tinted, thus having one or more layers of metal oxide coating, providing the glazing with various thermal or aesthetic functions. In addition, the inner glass sheet and / or the outer glass sheet can be thermally or chemically toughened (such as IOX or Gorilla Glass type glasses marketed by Corning) and / or have electrochromic functions for controlling and varying the light transmission (TL) of said glazing.

[0024] The interlayer (3) is arranged between the first and second glass sheets, in other words 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 interlayer according to the invention comprises at least two viscoelastic outer layers (4) and (5), each being in direct contact with one of the two glass sheets and having a thickness of between 0.1 mm and 0.8 mm, the two outer layers being formed by a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid, said outer layers also being called "skin layers". Said outer layers (4) and (5) are assembled by means of an internal viscoelastic damping adhesive layer (6), and are defined below.

[0025] The two viscoelastic external layers (4) and (5), according to the invention, have a thickness of between 0.1 mm and 0.8 mm, preferably between 0.15 mm and 0.5 mm, preferentially between 0.2 mm and 0.4 mm, and more preferentially the thickness is equal to 0.38 mm.

[0026] These two external layers make it possible in particular to provide the entire viscoelastic interlayer, sandwiched between the two sheets of glass, with a sufficiently high shear modulus (G'); in other words, sufficient stiffness for the glazing. The shear modulus G' can be linked, in particular for an isotropic material, to the Young's modulus E' by the relation G'=E72(1 +v), where v is the Poisson's ratio of the material.

[0027] Each of these 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 by a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid. Preferably, the ionomer is a copolymer comprising at least one ethylene monomer and at least one ap-unsaturated carboxylic acid monomer and 1% to 100% of the acid groups of said copolymer are neutralized into carboxylic acid salts comprising carboxylate ions and metal counterions. The metal counterion may consist essentially of a zinc ion. Advantageously, from 15% to 45% of the acid groups of said copolymer are neutralized, and even more advantageously from 25% to 40%.

[0028] And more particularly, said copolymer has from 12% to 30% of a carboxylic acid monomer selected from acids in the group consisting of α-O-unsaturated acids having from 3 to 8 carbon atoms. Even more particularly, the copolymer has from 17% to 23% of carboxylic acid monomer.

[0029] The carboxylic acids that can be used as a monomer of the copolymer described above are selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, monomethylmaleic acid and mixtures thereof. Functional equivalents of carboxylic acids known to those skilled in the art can also be used such as carboxylate salts, anhydrides, esters, acid halides, amides, nitriles and similar compounds that can be converted to carboxylic acids or acid salts by hydrolysis.

[0030] It is for example possible to use in the present invention as ionomer resins based on ethylene and carboxylic acid, those described in the following patent applications: WO 2004 / 011755, WO 2006 / 057771 and WO 2007 / 064794. In particular, it is possible to use as viscoelastic external layers layers marketed by the company Dupont de Nemours called SentryGlass®. The viscoelastic damping adhesive internal layer (6), according to the invention, is arranged between the two external layers (4) and (5), and has a thickness of between 15 μm and 25 μm, preferably the thickness is equal to 25 μm and said internal layer is formed by a material comprising at least one acrylic polymer, at least one tackifying agent, and at least one plasticizing agent.

[0031] The inventors surprisingly found that the thickness of the internal adhesive viscoelastic damping layer (6) arranged between the two external layers (4) and (5) had to be between 15 μm and 25 μm in order to obtain better acoustic insulation of the laminated glazing.

[0032] The inner layer (6) according to the invention is therefore used to bond the two outer layers (4) and (5) of the interlayer (3) together and ensure the structural adhesion of the two sheets of glass in the laminated glazing, after drying and calendering, then this said inner layer is used to dampen vibrations and / or increase the loss of transmission to noise, in particular of airborne origin, over the frequency decade between 1 kHz and 10 kHz, at room temperature. And, the specific thickness of this inner layer ensures that the laminated glazing, according to the invention, has good acoustic properties.

[0033] Preferably, the inner layer (6) is positioned in the center of the interlayer (3), which is itself arranged between the first glass sheet and the second glass sheet (1, 2).

[0034] The material of the viscoelastic damping adhesive inner layer may have a glass transition temperature of between -55°C and 10°C inclusive, in particular between -45°C and +5°C, and preferably between -30°C and -5°C.

[0035] According to the 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 as described in ASTM-D-3418 for differential scanning calorimetry. The measuring device used by the applicant is the Discovery DSC model from TA Instruments.

[0036] Preferably, a glass transition temperature Tg is determined by dynamic mechanical analysis (DMA) or dynamic mechanical spectrometry (DMA). The value of Tg is determined by plotting an isofrequency curve of the loss factor as a function of the temperature of the material. The temperature at which the value of the loss factor is maximum is equal to the glass transition temperature Tg. The glass transition temperature depends on the excitation frequency of the material. In this document, the term "glass transition temperature" means the glass transition temperature measured at a frequency of 1 Hz by DMA.

[0037] As stated above, the internal viscoelastic damping layer (6), according to the invention, is formed by a material comprising at least one acrylic polymer, at least one tackifying agent, and at least one plasticizing agent.

[0038] The acrylic polymer(s) may be formed from monomers 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, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, octyl acrylate, methacrylate octyl, isooctyl acrylate, isooctyl methacrylate, nonyl acrylate, nonyl methacrylate, isononyl 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.,

[0039] The acrylic polymer(s) may be copolymers, formed from at least two monomers chosen from the group formed by the monomers defined above.

[0040] 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 butylacrylate (BA). The mass ratio between 2-ethylhexyl acrylate (2-EHA) and butylacrylate (BA) may be between 2 and 4, and is preferably equal to 3.

[0041] Other commercial latexes comprising an acrylic polymer can be used to form the inner layer (6). For example, Arkema ® Encor 4028, Arkema ® Encor 4517, or Alberdingk ® A&B75070 latexes can be used.

[0042] The material may comprise another polymer that is not an acrylic polymer. Such another polymer may be formed from at least one monomer selected from styrene and methyl methacrylate.

[0043] The material may comprise a first acrylic polymer having a first glass transition temperature Tgi, and a second polymer, acrylic or non-acrylic, having a second glass transition temperature Tg2, higher than Tgi. The difference between the second glass transition temperature Tg2 and between the first glass transition temperature Tgi is preferably higher than 10°C, and preferably higher than 20°C. Thus, it is possible to increase the glass transition temperature of the material compared to the glass transition temperature of a material obtained solely with the first acrylic polymer. Indeed, the glass transition temperature obtained solely with the first acrylic polymer may be too low to present maximum damping of the material in an audible frequency range.

[0044] The polymer(s) may form an interpenetrating polymer network (IPN). The interpenetrating polymer network (IPN) type polymer system may thus be used, in the present invention, to form the core of the three-layer interlayer (3).

[0045] The Applicant proposes in particular to use a latex, i.e. an aqueous emulsion of polymer particles containing a RIP to form the inner layer of the tri-layer interlayer, as defined in the present application. In the present application, the term "latex" means a dispersion of polymer particles in water or in an aqueous solvent. The latex may comprise polymer particles having a core-shell structure. The core may be formed from an interpenetrating network of polymers (RIP) having a glass transition temperature (Tg) of between -50°C and -30°C, preferably between -45°C and -35°C, and the shell may be formed from a polymer having a glass transition temperature sufficiently low to allow the particles to coalesce after drying.The glass transition temperature of the shell may be lower than that of the core, and may preferably be lower than -50°C, and more preferably lower than -60°C. The RIP thus comprises a first crosslinked polymer and a second polymer, which may be crosslinked or non-crosslinked. In a preferred embodiment of the invention, the second polymer is non-crosslinked. In this case, the RIP is a so-called "semi-interpenetrating polymer network": semi-RIP (in English semi-IPN). The second polymer may be linear or branched.

[0046] In particular, the mass fraction of the acrylic polymer(s) in the internal adhesive viscoelastic damping layer (6) of the material is between 0.21 and 0.62, in particular between 0.21 and 0.51, and preferably between 0.21 and 0.35.

[0047] In the present application, "mass fraction" of a first element in a second element means the ratio of the mass of the first element to the mass of the second element.

[0048] The addition of tackifying agent and / or plasticizing agent to at least one acrylic polymer provides a means of adhesion between the two viscoelastic outer layers.

[0049] The tackifying agent may be chosen from natural tackifying resins, in particular rosins and terpenes, and synthetic tackifying resins such as aliphatic or aromatic resins derived from petroleum. The tackifying agent may comprise a hydrogenated resin, and preferably a hydrogenated rosin resin. The hydrogenated resin may comprise a glycerol ester of wood resin, preferably abietic acid. The hydrogenated resin may comprise a hydrogenated rosin ester (for example, a resin of the brand Arakawa ® KE-311 or KE 100 or FTE019 or FTE020).

[0050] In particular, the mass fraction of the tackifying agent(s) in the internal adhesive viscoelastic damping layer (6) is between 0.17 and 0.60, in particular between 0.22 and 0.35, and preferably between 0.22 and 0.26.

[0051] The plasticizing agent, according to the invention, makes it possible to optimize the rheological properties of the composition of the viscoelastic damping adhesive inner layer in order to obtain the best acoustic performance for the glazing. The plasticizing agent may comprise at least one element chosen from a citrate, an adipate, a glycol and a triethylene glycol derivative. The citrate may be acetyl-tributyl citrate. The adipate may be triethylene glycol bis(2-ethylhexanoate) (for example marketed under the name WVC 3800 from Celanese®).

[0052] In particular, the mass fraction of the plasticizing agent(s) in the internal adhesive viscoelastic damping layer (6) is between 0.07 and 0.43, in particular between 0.12 and 0.31, and preferably between 0.16 and 0.26.

[0053] Thus, advantageously, the material has a mass fraction of the acrylic polymer(s) in the internal adhesive viscoelastic damping layer (6) of between 0.21 and 0.62, a mass fraction of the plasticizing agent(s) in the internal layer (6) of between 0.07 and 0.43 and a mass fraction of the tackifying agent(s) in the internal layer (6) of between 0.17 and 0.60.

[0054] Advantageously, the material has a mass fraction of the acrylic polymer(s) in the internal adhesive viscoelastic damping layer (6) of between 0.21 and 0.51, a mass fraction of the plasticizing agent(s) in the internal layer (6) of between 0.12 and 0.31 and a mass fraction of the tackifying agent(s) in the internal layer (6) of between 0.22 and 0.35.

[0055] Advantageously, the material has a mass fraction of the acrylic polymer(s) in the internal adhesive viscoelastic damping layer (6) of between 0.21 and 0.35, a mass fraction of the plasticizing agent(s) in the internal layer (6) of between 0.16 and 0.26 and a mass fraction of the tackifying agent(s) in the internal layer (6) of between 0.22 and 0.26.

[0056] Advantageously, the material has a mass fraction of the acrylic polymer(s) in the internal adhesive viscoelastic damping layer (6) of between 0.21 and 0.62, a mass fraction of the plasticizing agent(s) in the internal layer (6) of between 0.12 and 0.31 and a mass fraction of the tackifying agent(s) in the internal layer (6) of between 0.22 and 0.35. Advantageously, the material has a mass fraction of the acrylic polymer(s) in the internal adhesive viscoelastic damping layer (6) of between 0.21 and 0.62, a mass fraction of the plasticizing agent(s) in the internal layer (6) of between 0.16 and 0.26 and a mass fraction of the tackifying agent(s) in the internal layer (6) of between 0.22 and 0.26.

[0057] According to a preferred embodiment of the invention, the interlayer (3) further comprises two films (7) and (8) made of a material chosen from poly(ethylene-vinyl acetate) (EVA) and poly(ethylene terephthalate) (PET) and mixtures thereof, each of the two films being arranged between the internal viscoelastic damping adhesive layer (6) and one of the two external viscoelastic layers (4) or (5).

[0058] Thus, preferably the inner layer (6) is positioned in the center of the interlayer (3), which is itself 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 inner adhesive viscoelastic damping layer (6). And even more advantageously, the film (7) is also in direct contact with the outer viscoelastic layer (4) and the film (8) is also in direct contact with the outer viscoelastic layer (5). The thickness of each of the two films is preferably between 6 μm and 200 μm and more preferably between 12 μm and 50 μm. Thus, preferably, the interlayer (3) is made up of five layers, namely the inner adhesive layer (6), the films (7) and (8) and the outer viscoelastic layers (4) and (5).

[0059] The two films (7) and (8) have the advantage of preventing components of the internal layer from going into the external layers and thus making it possible to avoid any existing chemical incompatibilities between the components of the internal layer and those of the external layers of the interlayer.

[0060] Figure 2 - [Fig. 2] schematically illustrates a detail of a section of a laminated glazing according to a preferred embodiment of the invention as described above.

[0061] Preferably, the layers (or films) between the inner glass sheet (1) and the inner layer (6) and the layers between said inner layer (6) and the outer glass sheet (2) are identical; in other words, they are of the same chemical nature and have the same thicknesses. The invention also relates to a side window or a windshield of a vehicle comprising laminated glazing as described above.

[0062] The invention also relates to a method for manufacturing laminated glazing as described above, comprising the following steps: a) providing an inner glass sheet (1) and an outer glass sheet (2), b) placing between the inner faces of the two glass sheets (1, 2) an interlayer (3) comprising:

[0063] - a first viscoelastic layer (4) formed by a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid and having a thickness of between 0.1 mm and 0.8 mm,

[0064] - a viscoelastic damping adhesive layer (6) formed by a material comprising at least one acrylic polymer, at least one tackifying agent and having a thickness of between 15 μm and 25 μm, and

[0065] - a second viscoelastic layer (5) formed by a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid and having a thickness of between 0.1 mm and 0.8 mm, c) assembling the two sheets of glass (1, 2) and the interlayer (3) by lamination to form a laminated glazing, and d) degassing said laminated glazing by autoclaving.

[0066] According to a preferred embodiment, the interlayer (3) is manufactured according to the method comprising the following steps:

[0067] - provision of a first sheet made of a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid and having a thickness of between 0.1 mm and 0.8 mm,

[0068] - depositing on one of the faces of said first sheet based on ethylene and carboxylic acid copolymer, a liquid composition comprising a latex, a tackifying agent, and a plasticizing agent, the latex comprising an emulsion, the emulsion comprising an aqueous continuous phase and a dispersed phase, the dispersed phase comprising at least one acrylic polymer,

[0069] - drying said composition so as to form a viscoelastic damping adhesive layer having a thickness of between 15 μm and 25 μm,

[0070] - application to said adhesive layer thus formed of a second sheet made of a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid and having a thickness of between 0.1 mm and 0.8 mm.

[0071] The liquid composition may be a dilution of the latex, tackifying agent and plasticizing agent in an aqueous phase.

[0072] The step of depositing the liquid composition comprising a latex, a tackifying agent, and a plasticizing agent on the first sheet of a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid and having a thickness of between 0.1 mm and 0.8 mm can be carried out by the known method of liquid roll-to-roll deposition, more precisely by the method of a reverse roll coater fed with the latex via a slit (nip-fed reverse roll).

[0073] In addition, the step of drying said composition is preferably carried out continuously, at room temperature and / or in an oven at a temperature between 40°C and 120°C, preferably between 60°C and 100°C. Advantageously, this drying step is carried out under a reduced pressure between 0.01 atm and 1 atm, preferably between 0.1 atm and 0.5 atm, ideally at a pressure equal to 0.25 atm.

[0074] Preferably, the interlayer (3) further comprises two films (7) and (8) made of a material chosen 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), and each of the two films is 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, the liquid composition comprising a latex, a tackifying agent, and a plasticizing agent is then deposited on one of the faces of the first film made of a material chosen from poly(ethylene-vinyl acetate) (EVA) and poly(ethylene terephthalate) (PET) and mixtures thereof.

[0075] The process parameters such as the tension of the ethylene and carboxylic acid copolymer-based sheets and the stability of the rollers and the feed 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 exhibit any corrugation defects. 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 building glazing to dampen vibrations and / or increase the transmission loss to noise, in particular of airborne origin, over the audible frequency decade between 1 kHz and 10 kHz, at room temperature. In the case where the glazing according to the invention is used as a windshield, it naturally meets all the conditions of United Nations Regulation No. 43 (known as Regulation R43) for resistance to hard impacts to ensure its mechanical strength.Furthermore, the other glazings according to the invention have, in addition to improved acoustic insulation properties, good mechanical properties due to the particular choice of the interlayer (3) according to the invention.

[0076] Characterization of the mechanical properties of laminated glazing

[0077] A laminated glazing unit according to the invention is prepared comprising:

[0078] - an inner glass sheet with a thickness of 2.1 mm,

[0079] - a viscoelastic outer layer having a thickness of 0.38 mm and comprising ionomers based on ethylene and carboxylic acid copolymer,

[0080] - an internal viscoelastic damping adhesive layer having a thickness of 25 μm; said internal layer comprising two types of acrylic polymers, formed from 2-ethylhexyl acrylate and isobutyl acrylate, and a tackifying agent such as ARAKAWA®TFE20-011 and a plasticizing agent such as alberdingk®EP 123545 K,

[0081] - a viscoelastic outer layer having a thickness of 0.38 mm and comprising ionomers based on ethylene and carboxylic acid copolymer,

[0082] - an outer glass sheet with a thickness of 2.1 mm.

[0083] We take a laminated glazing according to the prior art (called “Acoustic PVB”) consisting of two sheets of glass with a thickness of 2.1 mm, said glazing being laminated using a three-layer viscoelastic interlayer comprising two external layers of PVB and an internal layer with a thickness equal to 0.10 mm comprising PVB and plasticizing agents.

[0084] The aforementioned laminated glazing is then subjected to the measurement of the shear modulus (in Pa); this quantity characterizes the stiffness of the interlayer and consequently its acoustic performance. The shear modulus is measured by DMTA using the EN 16613 standard (plane shear method)

[0085] Thus, Figure 3 - [Fig. 3] illustrates the measurements of the shear modulus of the laminated glazing according to the invention and of the laminated glazing according to the prior art in a frequency range between 100 Hz and 10,000 Hz.

[0086] The curve formed by a continuous line illustrates the shear modulus of the laminated glazing according to the prior art while the curve formed by broken lines illustrates the shear modulus of the laminated glazing according to the invention.

[0087] The results reported in Figure 3 show that a laminated glazing according to the invention has better mechanical properties compared to a laminated glazing according to the prior art since the shear modulus of the interlayer according to the invention is approximately 100 times greater than that obtained for the PVB interlayer of the prior art.

[0088] Acoustic characterization of laminated glazing

[0089] 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 other laminated glazings outside the invention (comparative), a numerical simulation was carried out. The acoustic model is based on the finite element method so as to reproduce the behavior of the acoustic attenuation according to the NF EN ISO 10140 standard.

[0090] Thus, Figure 4 - [Fig. 4] illustrates the acoustic attenuation of laminated glazing of different configurations subjected to airborne noise produced according to standard NF EN 10140.

[0091] •The curve formed by a continuous line with triangles illustrates the acoustic attenuation of a glazing according to the prior art consisting of two sheets of glass 2.1 mm thick, said glazing being laminated using a three-layer viscoelastic interlayer comprising two external layers of PVB and an internal layer with a thickness equal to 0.15 mm comprising PVB and plasticizing agents (called “Acoustic PVB”).

[0092] • The curves formed respectively by broken lines with dotted lines (named “SGP + 5 pm latex”), by a continuous line with dots (named “SGP + 10 pm latex”), by a continuous line with squares (named “SGP + 35 pm latex”) and by a continuous line (named “SGP + 50 pm latex”) illustrate the acoustic attenuation of laminated glazings outside the invention (comparative examples). Said laminated glazings consist of an internal adhesive viscoelastic damping layer comprising two types of acrylic polymers, formed from 2-ethylhexyl acrylate and isobutyl acrylate and comprising as tackifying agent: ARAKAWA®TFE20-011 and as plasticizing agent: alberdingk®EP 123545 K.Said inner layer has a thickness of 5 μm, 10 μm, 35 μm and 50 μm respectively and is located between two viscoelastic outer layers having a thickness of 0.38 mm and comprising ionomers based on ethylene and carboxylic acid copolymer. Said outer layers are themselves located between two glass sheets with a thickness equal to 2.1 mm.

[0093] • The curves formed respectively by a continuous line with diamonds (named “SGP + 15pm latex”), and by broken lines (named “SGP + 25pm latex”) illustrate the acoustic attenuation of laminated glazing according to the invention. Said laminated glazings consist of an internal viscoelastic damping adhesive layer comprising two types of acrylic polymers, formed from 2-ethylhexyl acrylate and isobutyl acrylate and comprising as tackifying agent: ARAKAWA®TFE20-011 and as plasticizing agent: alberdingk®EP 123545 K. Said internal layer has a thickness of 15 μm and 25 μm respectively and is located between two external viscoelastic layers having a thickness of 0.38 mm and comprising ionomers based on ethylene and carboxylic acid copolymer. Said external layers are located between two glass sheets with a thickness equal to 2.1 mm.

[0094] The results reported in Figure 4 show:

[0095] - an improvement in the acoustic attenuation of airborne noise of the laminated glazing according to the invention of at least 2.7 dB over all frequencies from 5000 Hz to 10000 Hz, at room temperature, compared to the laminated glazing according to the prior art (acoustic PVB), and

[0096] - an improvement in the acoustic attenuation to airborne noise of the laminated glazings according to the invention of at least 1.0 dB over the entire frequency range from 5000 Hz to 10000 Hz, at room temperature, compared to laminated glazings whose internal adhesive viscoelastic damping layer, arranged between the two external layers based on ethylene and carboxylic acid copolymer, has a thickness outside the range between 15 pm and 25 pm (i.e. having a thickness equal to 5 pm, 10 pm, 35 pm or 50 pm). Thus, a laminated glazing according to the invention has both good acoustic properties and good mechanical properties.

Claims

[CLAIMS] 1. Laminated glazing comprising an inner glass sheet (1) and an outer glass sheet (2), each comprising an inner face and an outer face, and comprising, between the inner faces of the two glass sheets, an interlayer (3), characterized in that said interlayer comprises: - at least two viscoelastic external layers (4) and (5) having a thickness of between 0.1 mm and 0.8 mm, each of the two external layers being in direct contact with one of the two glass sheets and being formed by a material comprising at least one ionomer based on a copolymer of ethylene and carboxylic acid, and - an internal viscoelastic damping adhesive layer (6), arranged between the two external layers (4) and (5), said viscoelastic damping adhesive layer having a thickness of between 15 μm and 25 μm and being formed by a material comprising at least one acrylic polymer, at least one tackifying agent, and at least one plasticizing agent.

2. Laminated glazing according to claim 1, in which the ionomer(s) is one or more copolymer(s) comprising at least one ethylene monomer and at least one ap-unsaturated carboxylic acid monomer, and 1% to 100% of the acid groups of said copolymer(s) being neutralized into carboxylic acid salts comprising carboxylate ions and metal counterions.

3. Laminated glazing according to any one of the preceding claims, in which the material of the internal adhesive viscoelastic damping layer (6) has a glass transition temperature (Tg) of between -55°C and 10°C.

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

35.

5. Laminated glazing according to any one of the preceding claims, in which the material has a mass fraction of the tackifying agent(s) in the internal adhesive viscoelastic damping layer (6) of between 0.17 and 0.60, in particular of between 0.22 and 0.35, and preferably of between 0.22 and 0.

26.

6. Laminated glazing according to any one of the preceding claims, in which the tackifying agent comprises a hydrogenated resin, and preferably a hydrogenated rosin resin.

7. Laminated glazing according to any one of the preceding claims, in which the material has a mass fraction of the plasticizing agent(s) in the internal adhesive viscoelastic damping layer (6) of between 0.07 and 0.43, in particular of between 0.12 and 0.31, and preferably of between 0.16 and 0.

26.

8. Laminated glazing according to any one of the preceding claims, in which the acrylic polymer(s) are formed from monomers chosen from the group formed by 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, pentyl acrylate, pentyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, methacrylate cyclohexyl, octyl acrylate, octyl methacrylate, isooctyl acrylate, isooctyl methacrylate, nonyl acrylate, nonyl methacrylate, isononyl 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.

9. Laminated glazing according to any one of the preceding claims, in which the material comprises a first acrylic polymer having a first glass transition temperature T g i, and a second polymer having a second glass transition temperature T g2 , greater than T gi, the difference between the second glass transition temperature T g2 and between the first glass transition temperature T gi being preferably greater than 10°C, and preferably greater than 20°C.

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

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

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

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

14. Side window or windshield of a vehicle comprising laminated glazing according to any one of the preceding claims.

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

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

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