Adhesive composition for glass article comprising expansion means and laminated glazing for automobile comprising such a composition

Abstract

Adhesive composition for glass article comprising expansion means and laminated glazing for automobile comprising such a composition The invention relates to an adhesive composition for a glass article comprising poly(vinyl butyral) (PVB) and at least one expansion means. The invention also relates to a laminated glazing for automobile comprising at least two sheets of glass, and as a lamination interlayer, a layer of such an adhesive composition. The invention finally relates to methods for obtaining such a laminated glazing and for disassembling it comprising a step of heating the laminated glazing for automobile to a temperature of from 110°C to 260°C, in particular from 120°C to 250°C and preferably from 180°C to 220°C for a duration of from 0.5 to 10 minutes, in particular from 1 to 5 minutes and preferably from 1.5 to 3 minutes. Figure for abstract: None

Description

Title of the invention: Adhesive composition for a glass article comprising expansion means and laminated glazing for an automobile comprising such a composition Prior art

[0001] The present invention belongs to the field of disassembly and recycling of glass articles, in particular laminated glass, notably used in the automotive field.

[0002] The recycling of used glass is today a problem of prime importance, with the challenges of reducing the amount of vitrifiable raw material and reducing the environmental footprint of new glass.

[0003] Laminated glass consists of sheets of glass, bonded together by means of an adhesive composition deposited so as to form an interlayer polymeric film, typically based on poly(vinyl butyral) (PVB).

[0004] This type of glass is particularly appreciated for applications in the automotive field. Indeed, in the event of glass breakage, the polymeric film helps maintain cohesion of the entire glazing and prevents glass shards. This type of glazing is therefore mandatory for windshields of modern vehicles. It is also used for sunroofs or side windows.

[0005] However, the difficulty of recycling laminated glass is one of its main disadvantages since it requires the separation of two sheets of glass from an interlayer adhesive polymeric layer.

[0006] Typically, laminated glass is currently recycled by means of a crushing operation. However, at the end of this operation, there remains in the recovered materials: 20% by weight of glass in the interlayer polymer (such as PVB) and 5% by weight of interlayer polymer (such as PVB) in the glass.

[0007] It is therefore necessary to obtain better separation at the interfaces of the interlayer polymer and the glass when recycling laminated glass in order, on the one hand, to improve the quality and quantity of recovered glass but also to enable recycling of the interlayer polymer, reducing its impact on the cost and durability of a windshield. Statement of the invention

[0008] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above, by proposing a solution which makes it possible to disassemble the interlayer polymeric film formed from an adhesive composition and the glass sheets in a laminated glazing unit.

[0009] To this end, and according to a first aspect, the invention relates to an adhesive composition for a glass article comprising poly(vinyl butyral) (PVB) and an expansion means.

[0010] Such a composition according to the invention finds its interest, in particular, in the fact that it allows, in the context of its application as an interlayer film in laminated glazing, to weaken on demand the cohesion forces at the interfaces of the PVB and the glass by means of the expansion means which it comprises.

[0011] In particular, an adhesive composition according to the invention may comprise at least one expansion means chosen from microcapsules and / or chemical expansion agents.

[0012] The microcapsules used in a composition according to the invention consist of a volatile liquid core and a polymeric shell.

[0013] The volatile liquid core of the microcapsules vaporizes when subjected to heating, which leads to an increase in volume of the microcapsules and / or to a release of said core in the form of gas into the adhesive composition.

[0014] These microcapsules can be called "expandable microcapsules" because an increase in their volume is obtained by heating to a temperature greater than or equal to the glass transition temperature of the polymer shell and to the temperature of the vaporization temperature of the volatile liquid core. The increase in volume due to the change in state of the core then creates sufficient pressure for the deformation of the shell.

[0015] The increase in volume of the microcapsules and / or the release of gas into the adhesive composition obtained after heating makes it possible to weaken the cohesion forces at the PVB / glass interfaces and thus promotes the separation of two sheets of glass for disassembly of a laminated glazing unit, in particular for a laminated glazing unit intended for the automotive industry.

[0016] Such microcapsules and their methods of obtaining are for example described in applications US 3,615,972 A; US 4,049,604 A; US 4,016,110 A; US 4,582,756 A; US 2018 / 0355216 Al; JP H09 / 019.635 A; WO 2002 / 096635 A1; WO 2007 / 142593 A1; EP 0 486 080 Al; EP 0 572 233 Al; EP 1 149 628 A1; EP 1 964 903 Al and EP 1 508 604 AL

[0017] The shell of the microcapsules is composed of at least one thermoplastic polymer having a high glass transition temperature, in particular greater than or equal to the vaporization temperature of the liquid core.

[0018] Such polymers are capable of being obtained from the polymerization of at least one monomer chosen from (meth)acrylic monomers, aromatic alkenyls, vinyl derivatives, acid monomers and mixtures thereof.

[0019] By (meth)acrylic monomers is meant the monomers of formula general CH2CH(R')C(O)OR where R is selected from C1-C12 alkyl, C3-C10 cycloalkyl or an aromatic group, optionally substituted by a hydroxy radical or R is a hydrogen atom, and R' is chosen from a hydrogen atom and a methyl.

[0020] Among the (meth)acrylic monomers suitable for the present invention, mention may be made of methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, propyl methacrylate, lauryl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.

[0021] By aromatic alkenyls is meant the monomers of general formula Ar-CHCH2 where Ar represents an aromatic hydrocarbon radical, optionally substituted by a halogen.

[0022] Among the aromatic alkenyls, mention may be made of styrene, rort / zo-methylstyrene, meta-methylstyrene, para-methylstyrene, ethylstyrene, vinyl xylene, chlorostyrene, bromostyrene and styrene derivatives such as vinylbenzyl chloride and para-tert-butylstyrene.

[0023] Among the vinyl derivatives, mention may be made of acrylonitrile, methacrylonitrile, vinyl halides, vinyl esters and vinyl ethers.

[0024] Among the vinyl halides, mention may be made of vinyl chloride, vinyl bromide and vinylidene chloride.

[0025] By vinyl esters is meant the compounds of general formula CH2 CHOC(O)R where R is a CrCi7 alkyl.

[0026] Among the vinyl ester monomers, mention may be made of vinyl acetate, vinyl benzoate, vinyl butyrate, vinyl stearate, vinyl laurate, vinyl myristate and vinyl propionate.

[0027] Among the vinyl ethers, mention may be made of methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, sec-butyl vinyl ether and mixtures thereof.

[0028] Among the acid monomers, mention may be made of acrylic acid, methacrylic acid, itaconic acid, citraconic acid, maleic acid, fumaric acid and vinylbenzoic acid.

[0029] A thermoplastic polymer of a microcapsule suitable for the invention can be obtained by the copolymerization of several of the monomers cited above.

[0030] A thermoplastic polymer of a microcapsule suitable for the invention is typically obtained from acrylonitrile, acrylic ester and / or olefins.

[0031] In one embodiment of the invention, the microcapsules implemented in a composition according to the invention comprises a shell based on an acrylonitrile copolymer such as the acrylonitrile / methacrylonitrile copolymer or the acrylonitrile / methacrylonitrile / hydroxyethyl methacrylate copolymer.

[0032] In another embodiment of the invention, the microcapsules used in a composition according to the invention comprise a polymeric shell formed from monomers chosen from (meth)acrylic monomers, (meth)acrylonitriles and their mixtures. Preferably, said shell is obtained by the polymerization of monomers chosen from methyl methacrylate, acrylonitrile and their mixtures.

[0033] Preferably, the thermoplastic polymer constituting the shell of a microcapsule suitable for the invention has a light transmission greater than or equal to 70%, in particular at least 80% and preferably at least 88%.

[0034] The volatile liquid core of the microcapsules consists of a liquid whose vaporization temperature is low. A so-called "low" vaporization temperature for said liquid is less than or equal to the glass transition temperature of the shell polymer.

[0035] Said liquid may have a vaporization temperature of from 50°C to 200°C.

[0036] Such a liquid may be a hydrocarbon such as pentane, neopentane, isopentane, cyclopentane, acetylene, hexane, cyclohexane, methylcyclohexane, heptane, cycloheptane, heptene, octane, isooctane, cyclooctane, octene and mixtures thereof.

[0037] Among the hydrocarbons, alkanes which are liquid at room temperature such as pentane, neopentane, isopentane, cyclopentane, hexane, cyclohexane, methylcyclohexane, heptane, cycloheptane, octane, isooctane and cyclooctane are preferred.

[0038] Among the other compounds capable of constituting the core of the microcapsules, mention may be made of tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane and trimethyl-n-propylsilane.

[0039] The microcapsules suitable for the invention can therefore contain a liquid having a low vaporization temperature, in particular chosen from hydrocarbons, and preferably chosen from alkanes.

[0040] In particular, the liquid core of a microcapsule suitable for the invention comprises at least one hydrocarbon, preferably chosen from isopentane, pentane, hexane, cyclohexane, methylcyclohexane, heptane, heptene and mixtures thereof, and more preferably chosen from isopentane and methylcyclohexane.

[0041] The microcapsules suitable for the invention may comprise from 3% to 50% by weight of volatile liquid and preferably from 5% to 30% by weight of volatile liquid per relative to the total weight of a microcapsule.

[0042] The microcapsules suitable for the invention have a dimension, in particular a diameter, less than or equal to 5 μm, in particular less than or equal to 1 μm, and preferably less than or equal to 500 nm.

[0043] When the microcapsules are spherical in shape, the dimension discussed in the preceding paragraph corresponds to the diameter of the microcapsules, in particular the average diameter of a set of particles.

[0044] Indeed, the smaller the microcapsules, the better the transparency of an adhesive composition comprising them and therefore of a laminated glazing containing them. This is observed by a greater light transmission for an adhesive composition comprising microcapsules of smaller dimensions.

[0045] Conversely, an adhesive composition comprising microcapsules larger than 5 μm does not have satisfactory transparency for application in automotive glazing.

[0046] An adhesive composition according to the invention may contain from 1% to 10% by weight of microcapsules as described above relative to the total weight of the adhesive composition, in particular from 2% to 8% by weight and preferably from 3% to 7% by weight of said microcapsules.

[0047] An adhesive composition according to the invention may also comprise, as expansion means, chemical expansion agents.

[0048] Chemical blowing agents are compounds capable of releasing gas by thermal decomposition. These are known and typically used to form polymeric foams.

[0049] According to the same principle as that set out above, the gas released by these chemical expansion agents makes it possible to weaken the cohesion forces at the PVB / glass interfaces and ensures easy disassembly of laminated glazing for automobiles.

[0050] The chemical blowing agents suitable for the invention have carbon / oxygen (CO), nitrogen (NN) and / or nitrogen / sulfur (NS) bonds capable of breaking upon the input of heat. This breaking results in the release in gaseous form of carbon dioxide (CO2), ammonia (NH3), nitrogen (N2), sulfur dioxide (SO2) and / or water (H2O).

[0051] The chemical expansion agents suitable for the invention may be chosen from carbonates; azo compounds, in particular hydrazides such as azodicarbonamide; hydrazine derivatives; nitroso- and / or tetrazole compounds.

[0052] Among the carbonates suitable for use as chemical expansion agents according to the invention, mention may be made of sodium bicarbonate, sodium carbonate and zinc carbonate.

[0053] Among the azo compounds suitable for use as chemical expansion agents according to the invention, mention may be made of azobisisobutyronitrile and hydrazides such as azobicarbonamide and diisopropyl azodicarboxylate.

[0054] Among the hydrazine derivatives suitable for use as a chemical blowing agent according to the invention, mention may be made of semicarbazide; polymeric sulfonic hydrazides such as poly(methacryloyl toluenesulfonylhydrazide); and sulfonylsemicarbazides such as para-toluenesulfonylsemicarbazide and 4,4'-oxybis(benzenesulfonylsemicarbazide).

[0055] Among the nitroso- compounds suitable for use as chemical expansion agents according to the invention, mention may be made of dinitrosopentamethylenetetramine.

[0056] Among the tetrazoles suitable for use as chemical expansion agents according to the invention, mention may be made of 5-phenyltetrazole and 5-aminotetrazole.

[0057] The invention also relates to a laminated glazing for an automobile comprising at least two sheets of glass and, as a lamination interlayer, a layer of adhesive composition according to the invention.

[0058] Conventionally, the main faces of laminated automotive glazing are numbered from 1 to 4: • the Fl face is the external (outer) face of the exterior glass, preferably tinted; • face F2 is the internal face (lamination interlayer side) of the exterior glass; • the lamination interlayer, here consisting of the adhesive composition according to the invention; • face F3 is the internal face (interlayer side of the lamination) of the interior glass, preferably colorless and often of thickness less than or equal to that of the exterior glass; • face F4 is the internal face (passenger compartment side) of the interior glass.

[0059] The laminated glazing according to the invention may have a haze of at most 2%, in particular of aa plus 1.5%, and preferably less than or equal to 1%.

[0060] In the laminated glazing for automobiles according to the invention, the adhesive composition may have a thickness of from 100 μm to 2100 μm, in particular from 300 μm to 1100 μm and preferably from 650 μm to 850 μm.

[0061] In the laminated glazing for automobiles according to the invention, the glass sheets may have a thickness of from 0.1 mm to 6 mm, in particular from 0.3 mm to 5 mm and preferably from 0.7 mm to 3 mm.

[0062] The glass sheets suitable for laminated glazing for automobiles according to the invention may be made of mineral glass, in particular chosen from soda-lime, aluminosilicate and borosilicate glasses.

[0063] Preferably, the glass sheets suitable for laminated glazing for automobiles according to the invention are chosen from soda-lime-silica glasses.

[0064] The glass sheets suitable for laminated automotive glazing according to the invention are preferably colorless, and have a light transmission factor of at least 85%, or even 90%, preferably within the meaning of standard EN 410:1998.

[0065] The glass sheets suitable for laminated glazing for automobiles according to the invention may be clear glasses (with a light transmission greater than or equal to 90% for a thickness of 4 mm), for example glasses of standard soda-lime compositions such as Planilux® from the company Saint-Gobain Glass, or extra-clear (with a light transmission greater than or equal to 91.5% for a thickness of 4 mm), for example a soda-lime-silica glass with less than 0.05% by weight of Fe III or Fe2O3 such as Diamant® glass from Saint-Gobain Glass, or Optiwhite® from Pilkington, or B270® from Schott, or other composition described in document WO04 / 025334. The glass sheets suitable for laminated glazing for automobiles according to the invention may also be made of Planiclear® glass from the company Saint-Gobain Glass.

[0066] The glass sheets suitable for laminated glazing for automobiles according to the invention may also be curved and / or tempered glass, in particular thermally tempered, preferably at a temperature greater than or equal to 450°C, or better still greater than or equal to 600°C.

[0067] In one embodiment of the invention, the laminated glazing for an automobile according to the invention is a windshield or a roof, in particular a windshield.

[0068] When the laminated glazing for an automobile according to the invention is a roof, it must meet current automobile specifications, in particular for light transmission TL and / or energy transmission TE and / or energy reflection RE and / or for total transmission of solar energy TTS.

[0069] For an automobile roof, these being often tinted, a non-zero light transmission TL is preferred, and even at least 0.5% or at least 2% and at most 40% and even at most 20%.

[0070] For an automobile roof, a haze of less than or equal to 2% is preferred.

[0071] For an automobile roof, one or more of the following criteria is preferred: • At most 10% and preferably between 4% and 6%, • Re, in particular on the side of the external face, towards the outside of the vehicle, of at least plus 10%, and preferably between 4% and 5%, • TTS less than 30%, in particular less than 26% and preferably between 20% and 23%.

[0072] When the laminated glazing for automobiles according to the invention is a windshield, the light transmission may be greater than or equal to 70%, in particular greater than or equal to 75% and preferably at least 80%.

[0073] When the laminated glazing for an automobile according to the invention is a windshield, the following configuration can be provided: • the Fl face is the external (outer) face of the outer glass, preferably colorless with little tinting; • face F2 is the internal face (lamination interlayer side) of the exterior glass; • the lamination interlayer is the adhesive composition according to the invention, if necessary tinted in order to compensate for the low tint of the exterior glass; • face F3 is the internal face (lamination interlayer side) of the interior glass, preferably colorless; • face F4 is the internal face (passenger compartment side) of the interior glass.

[0074] A laminated glazing according to the invention is easily disassembled by heating, which provides heat to the adhesive composition comprising an expansion means, under the effect of which said expansion means increases the total volume of the adhesive composition and weakens the cohesion forces at the interfaces between the adhesive composition and the glass sheets.

[0075] This easy disassembly is particularly advantageous for the recycling of automotive glazing.

[0076] The invention therefore also relates to a method for disassembling a laminated glazing for an automobile according to the invention, comprising a step of heating the laminated glazing for an automobile to a temperature of from 110°C to 260°C, in particular from 120°C to 250°C and preferably from 180°C to 220°C for a duration of from 0.5 to 10 minutes, in particular from 1 to 5 minutes and preferably from 1.5 to 3 minutes.

[0077] In a particular embodiment, the heating step is carried out by means of an oven, a hot air gun, infrared rays, microwaves or by induction.

[0078] The disassembly method according to the invention has the advantage of being easily implemented and of making it possible to recover in a short time the constituent elements of the laminated glazing for automobiles (adhesive composition and glass sheets) which are not polluted, i.e. in which less than 5% by weight of the other constituents of the automotive glazing remain.

[0079] The invention finally relates to a method for obtaining laminated glazing for automobiles according to the invention, comprising a step of applying an adhesive composition according to the invention to one face of a glass sheet and then a step of placing a second glass sheet on the adhesive composition.

Claims

Claims

1. Adhesive composition for a glass article comprising poly(vinyl butyral) (PVB), characterized in that it further comprises at least one expansion means.

2. Adhesive composition according to the preceding claim, in which the expansion means is chosen from microcapsules and / or chemical expansion agents.

3. Adhesive composition according to claim 2, wherein the microcapsules represent from 1 to 10% by weight relative to the total weight of the composition, in particular from 2 to 8% by weight and preferably from 3 to 7% by weight.

4. An adhesive composition according to claim 2 or 3, wherein the microcapsules comprise a polymeric shell formed from monomers selected from (meth)acrylic monomers, (meth)acrylonitriles and mixtures thereof, and preferably selected from methyl methacrylate, acrylonitrile and mixtures thereof.

5. An adhesive composition according to any one of claims 2 to 4, wherein the microcapsules comprise a liquid having a low vaporization temperature, in particular chosen from hydrocarbons, and preferably chosen from alkanes.

6. Adhesive composition according to any one of claims 2 to 5, wherein the microcapsules have a dimension, in particular an average diameter, less than or equal to 5 pm, in particular less than or equal to 1 pm and preferably less than or equal to 500 nm.

7. An adhesive composition according to claim 2, wherein the chemical blowing agents are selected from carbonates; azo compounds, in particular hydrazides such as azodicarbonamide; hydrazine derivatives such as semicarbazide, polymeric sulfonic hydrazides and sulfonylsemicarbazides; nitroso- and / or tetrazole compounds.

8. Laminated glazing for automobiles comprising at least two sheets of glass, characterized in that it comprises, as lamination interlayer, a layer of adhesive composition according to any one of the preceding claims.

9. Laminated automotive glazing according to the preceding claim, in which the layer of adhesive composition has a thickness of from 100 pm to 2100 pm, in particular from 300 pm to 1100 pm, preferably from 650 pm to 850 pm.

10. Laminated glazing for an automobile according to any one of claims 8 or 9, said laminated glazing being a windshield or a roof, in particular a windshield.

11. Laminated glazing for an automobile according to any one of claims 8 to 10, said laminated glazing being a windshield and having a light transmission greater than or equal to 70%, in particular greater than or equal to 75% and preferably at least 80%.

12. Laminated glazing for automobiles according to any one of claims 8 to 11, said laminated glazing having a haze of at most 2%, in particular at most 1.5%, and preferably less than or equal to 1%.

13. Method for obtaining laminated automotive glazing as defined in any one of claims 8 to 12, comprising a step of applying an adhesive composition as defined in any one of claims 1 to 7 to one face of a glass sheet and then a step of placing a second glass sheet on the adhesive composition.

14. A method of disassembling a laminated automotive glazing unit as defined in any one of claims 8 to 12, comprising a step of heating the laminated automotive glazing unit to a temperature of from 110°C to 260°C, in particular from 120°C to 250°C and preferably from 180°C to 220°C for a duration of from 0.5 to 10 minutes, in particular from 1 to 5 minutes and preferably from 1.5 to 3 minutes.

15. A disassembly method according to the preceding claim, wherein the heating step is carried out by means of an oven, a heat gun, infrared rays, microwaves or by induction.