Laminated glass containing photochromic polymer film

Abstract

The present invention relates to laminated glass comprising two glass sheets, which are laminated by at least one thermoplastic intermediate layer comprising at least one photochromic polymer film and a UV-shielding polymer film.

Description

Technical Field

[0001] The present invention is directed to laminated glass comprising two glass sheets, which is laminated by at least one thermoplastic interlayer comprising at least one photochromic polymer film and a UV shielding polymer film.

[0002] Safety laminated glass usually consists of two glass sheets and is laminated by a thermoplastic polymer film. Such films are generally made from plasticizer-containing polyvinyl acetals such as polyvinyl butyral (PVB).

[0003] In passenger cars and smart buildings, it is often desirable to incorporate specific functions into glazing. An example of such a function is the option to provide protection against glare and heat from natural sunlight.

[0004] One option for providing such light shielding is to incorporate a photochromic material into the interlayer film of laminated glass, as described, for example, in DE4024330A1.

[0005] A photochromic molecule is a compound that reversibly converts between two states with different colors in response to stimulation by electromagnetic radiation. Typically, upon irradiation with light within a specific wavelength band, isomerization, i.e., conversion from a relatively transparent form to a colored form, occurs. When the irradiation of light is stopped, the conversion from the colored form to the transparent form occurs spontaneously through a thermal process or is induced by irradiation with a wavelength different from that used for the conversion from the transparent state to the colored state.

[0006] Photochromic molecules are generally sensitive to prolonged exposure to sunlight and tend to decompose upon light irradiation, especially when in an excited state. In DE4024330A1, the photochromic molecules are dispersed in the bulk of the intermediate layer, so they decompose more slowly with exposure to sunlight from outside the vehicle / building compared to other systems with photochromic molecules directly coated on the glass or intermediate layer surface. However, the photochromic molecules in DE4024330A1 still decompose over time, albeit more slowly, causing the intermediate layer to discolor and the photochromic effect to become less pronounced.

[0007] Therefore, improved glazing that enables photochromic light shielding is still needed in industry.

[0008] Accordingly, the present invention relates to a laminated glazing comprising an intermediate layer having a first film oriented outward and substantially blocking all natural UV radiation from sunlight, and a second film incorporating photochromic molecules that are protected from exposure to natural UV radiation by the first film and can be selectively excited by a radiation source from the inside. With this setup, the photochromic molecules are not permanently exposed to natural UV light from sunlight and are excited only on demand, thus resulting in a much longer lifetime.

[0009] Furthermore, this configuration allows for the excitation of photochromic materials only in specific regions, thus providing a more versatile method for light shielding or glare protection.

[0010] Therefore, the present invention relates to a laminated glass for use as a vehicle glazing or building glazing, comprising a first glass sheet and a second glass sheet laminated by at least one thermoplastic interlayer, wherein the thermoplastic interlayer is - A film A directed towards the inside of a vehicle or building, comprising a polymer and a photochromic material that exhibits photochromic coloration when exposed to radiation with wavelengths of 400 nm or less, - Facing outwards from a vehicle or building, at least one film B comprising polyvinyl acetal, at least one plasticizer, and at least one UV absorber Includes, Film B, measured in accordance with ISO 13837, has a light transmittance of 5% or less for light with wavelengths of 400 nm or less. A radiation source having a wavelength of 400 nm or less, suitable for exciting at least one photochromic material in film A, is arranged to enable the excitation of the photochromic material. Regarding laminated glass.

[0011] The phrase "exhibits photochromic coloration when exposed to radiation with wavelengths below 400 nm" is intended to indicate that film A contains photochromic molecules that can be excited by exposure to radiation with wavelengths below 400 nm, i.e., within the invisible UV range, but do not exhibit, or substantially do not exhibit, photochromic coloration at wavelengths above 400 nm, i.e., within the visible range.

[0012] The radiation source may be any light source capable of emitting light with wavelengths of 400 nm or less, i.e., UV light, for example, LED emitted light with peak wavelengths of 280-405 nm, e.g., 365 nm, 385 nm, or 405 nm. Xenon lamp emitted light, fluorescent lamp emitted light, and natural sunlight are also suitable if properly re-induced inside a building or vehicle, or on interior glass.

[0013] In the simplest example, the radiation source is placed inside the vehicle or building. Alternatively, the radiation source can be placed at the edge or partial recess of the glazing, or even outside the vehicle or building. In this case, the radiation is induced to enable the excitation of the photochromic material in the second film.

[0014] Film B, measured in accordance with ISO 13837, has a light transmittance of 5% or less for light with wavelengths of 400 nm or less. Therefore, film B blocks most of the natural UV radiation from the outside and protects the photochromic molecules in film A. Preferably, film B has a light transmittance of 4% or less, more preferably 2.5% or less, most preferably 1% or less, and particularly 0.5% or less for light with wavelengths of 400 nm or less.

[0015] Preferably, the polymer in film A is polyamide, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene furanoate (PEF), polyethylene naphthalate (PEN), polyvinyl alcohol (PVA), polylactic acid (PLA), cellulose acetate, polymethyl methacrylate (PMMA), ionomer, or a combination thereof. Most preferably, the polymer in film A contains polyvinyl alcohol, consists of polyvinyl alcohol, or is essentially made of polyvinyl alcohol.

[0016] Depending on the desired color impression, various classes of photochromic compounds can be used as photochromic substances. Spiroxazines are one of the two most industrially important classes of organic photochromic colorants. In the late 1970s, it was discovered that spiroxazines are relatively resistant to UV photodegradation, and in the 1990s, they were successfully commercialized as sun-responsive colorants for ophthalmic lenses. In addition to their robustness, the spiroxazine class can be easily synthesized by standard organic synthesis. A special advantage is that the color can be easily fine-tuned by changing the structure of spiroxazines.

[0017] The most well-known are indolinospironaphthoxazines, for example, described in EP-A1-0146135 or DE-C2-3814631, and representative bruise-modifying compounds of this class, known from, for example, EP-B10141107, US-4637698, or EP-A1-0245020. All of these compounds provide a blue-violet or blue-to-blue-green color effect. For a green impression, one can use indolinospirobenzothiopyran, for example, described in US-4565779, or a photochromic compound from the aforementioned teachings, along with a yellow compound. The latter is known from, for example, EP-A1-0362771 or EP-A2-0246114, both of which also describe spiropyran or spirooxazine compounds. Another important group of spirooxazines is nitrospiropyran, which rapidly revert to its original isomer in less than 10 minutes in the dark.

[0018] Many of the indolinospirobenzoxazines mentioned in WO-A1-88 / 02371, as well as the flugides and flugimids from GB-2170202, give a deep orange to violet-red color effect. All of the above colors can also be achieved by representatives of the dihydroindridine and tetrahydroindridine classes described in DE-OS2906193, DE-A1-3220257, and DE-A1-3521432. By appropriately mixing different photochromic colors, achromatic, gray, or brownish tones can also be produced.

[0019] Photochromic substances are widely available commercially, for example, Sigma-Aldrich offers Photorome(registered trademark) I, such as 1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3'-[3H]naphtho[2,1-b][1,4]oxazine], or also from Sigma-Aldrich, as an example of a commercially available spiropyran, 8-methoxy-6-nitro-1'-3',3'-trimethylspiro[2H-1-benzopyran-2,2'-indoline]. And 6-nitro-1,3,3-trimethylspiro[2H-1-benzopyran-2,2'-indoline] is commercially available. 2,2'-Bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,1'-biimidazole is an example of a commercially available hexaarylbiimidazole-type photochromic dye available from TCI.

[0020] 4,4'-Bis(hexyloxy)-3-methylazobenzene is another example of a commercially available azobenzene-type photochromic dye, also available from TCI.

[0021] cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene is an example of a diarylethene-type photochromic dye available from TCI.

[0022] 2,3-dihydro-2-spiro-4'-[8'-aminonaphthalene-1'(4'H)-one]perimidine is a spiroperimidine-type photochromic dye also available from TCI.

[0023] Other photoswitchable chemicals include azobenzenes and their derivatives, diarylethenes and their derivatives, the simplest example being stilbene, and major examples of dithienylethene types. Another compound with photoswitchable properties is several quinones, and in particular phenoxynaphthacenequinone. Some imidazole derivatives also exhibit a color change when exposed to UV light and revert to their original color in the dark or in the absence of UV light. One example is the cyclophane form of hexaarylbiimidazole (HABI).

[0024] Similarly, the photochromic material is introduced into film A in the form of a nanoemulsion.

[0025] The nanoemulsion contains a polymer in which a large number of liquid nanodroplets are suspended. The term "nanodroplet" shall refer to a droplet having a diameter of 5 to 1000 nm. In order to transmit visible light without scattering, the nanodroplets preferably have a diameter of 200 nm or less.

[0026] US10227527B2 describes the preparation of such a nanoemulsion, in which a first solution of a photochromic material is prepared in a first solvent. A second solution of the polymer of film A is prepared in a second solvent. Then, both solutions are mixed and emulsified by a method known in the art, such as sonication or vortex mixing.

[0027] Preferably, the first solvent is oil and the second solvent is water. The oil may be of animal, plant-based, or mineral / petrochemical origin, such as alkanes and other mineral oils, silicone oils, vegetable oils, such as acid triglycerides, and liquid crystal materials.

[0028] The concentration of the photochromic material in the first solution is preferably 0.1% to 8% by weight, more preferably 1.2% to 5% by weight.

[0029] The second solution is preferably an aqueous solution of polyvinyl alcohol (PVA). The concentration is preferably within the range of 3% to 40% by weight, more preferably 10% to 30% by weight.

[0030] Preferably, film A has a thickness of 10 to 1000 μm, more preferably 20 to 500 μm, even more preferably 30 μm to 200 μm, and most preferably 40 μm to 150 μm.

[0031] If film A does not adhere well to the glass sheet, an additional film C having good adhesion to both the polymer of film A and the glass surface may be used between film A and the glass surface. A polymer material very suitable for film C is polyvinyl acetal, most preferably polyvinyl butyral.

[0032] On the other hand, it is important that film C does not block UV light from the radiation source used to excite the photochromic material.

[0033] Therefore, the laminated glass preferably includes a film C containing polyvinyl acetal and a plasticizer, where film C is placed between film A and a glass sheet, and film C has a light transmittance of 5% or more for light with wavelengths of 400 nm or less, as measured in accordance with ISO 13837.

[0034] More preferably, film C has a light transmittance of 7.5% or more, most preferably 10% or more, 15% or more, or 20% or more, for light having a wavelength of 400 nm or less.

[0035] In an alternative preferred embodiment, film A comprises polyvinyl acetal and a plasticizer. Thus, film A itself adheres well to the glass sheet, and an additional film C is not required. Most preferably, the polyvinyl acetal is polyvinyl butyral.

[0036] When both films A and B contain polyvinyl acetal, it may be preferable to have a barrier film between film A and film B to prevent the UV absorber in film B and / or the photochromic material in film A from diffusing into the other layer.

[0037] Preferably, the barrier film contains, consists of, or is essentially composed of modified or unmodified polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyvinyl alcohol (PVA). In the case of unmodified PET, biaxially oriented PET is preferably used, and in the case of modified PET, PETG (poly(cyclohexanedimethylene terephthalate-co-ethylene terephthalate)) is preferably used. Layers of polyvinyl alcohol or ethylene-modified polyvinyl alcohol (e.g., Exceval®) and ethylene-vinyl alcohol copolymer (e.g., EVAL®) are also useful as diffusion barriers.

[0038] Preferably, the photochromic substance has a low tendency to diffuse into the polyvinyl acetal of film A, and / or at least one UV absorber has a low tendency to diffuse into the polyvinyl acetal of film B.

[0039] UV absorbers that do not diffuse or hardly diffuse can be selected from polymer UV absorbers, UV absorbers having ionic groups, UV-absorbing nanoparticles, and organic UV absorbers that exist as particles in a film matrix.

[0040] Preferably, film B contains 0.1 to 5.0% by weight, more preferably 0.25 to 4.5% by weight, even more preferably 0.5 to 4.0% by weight, even more preferably 1.0 to 3.75% by weight, and even more preferably 2.0 to 3.5% by weight of a UV absorber. If two or more UV absorbers are present in film B, these values ​​shall be read as the total amount of UV absorbers.

[0041] Preferably, the compounds are selected from benzotriazole compounds, benzophenone compounds, triazine compounds, benzoate compounds, malonic acid ester compounds, or oxalic acid anilide compounds.

[0042] More preferably, the UV absorber is a benzotriazole-based UV absorber such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,ω-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(5-chloro-2-benzotriazol)-6-tert-butyl-p-cresol, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, and 2'-hydroxy-5'-t-octylphenyl)benzotriazole; These include 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate, and 4-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)-1-(2- Hindered amine-based UV absorbers such as (3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl)-2,2,6,6-tetramethylpiperidine; or benzoate-based UV absorbers such as 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate and hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate.

[0043] Suitable examples of triazine compounds include 6-(4-hydroxy-3,5-di-t-butylanilino)-2,4-bis-octylthio-1,3,5-triazine, 6-(4-hydroxy-3,5-dimethylanilino)-2,4-bis-octylthio-1,3,5-triazine, 6-(4-hydroxy-3-methyl-5-t-butylanilino)-2,4-bis-octylthio-1,3,5-triazine, and 2-octylthio-4,6-bis-(3,5-di-t-butyl-4-oxyanilino)-1,3,5-triazine.

[0044] Suitable examples of benzophenone compounds include 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2-carboxybenzophenone, and 2-hydroxy-4-n-octoxybenzophenone.

[0045] Suitable examples of malonic acid ester compounds include dimethyl 2-(p-methoxybenzylidene)malonate, tetraethyl-2,2-(1,4-phenylenedimethylidene)bismalonate, and 2-(p-methoxybenzylidene)-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)malonate.

[0046] Suitable examples of oxalic acid anilide compounds include oxalic acid diamides in which an aryl group is substituted on the nitrogen atom, such as N-(2-ethylphenyl)-N'-(2-ethoxy-5-t-butylphenyl)oxalic acid diamide, N-(2-ethylphenyl)-N'-(2-ethoxy-phenyl)oxalic acid diamide, and 2-ethyl-2'-ethoxy-oxyanilide (Sanduvor VSU, manufactured by Clariant, Inc.).

[0047] Furthermore, most preferably, the UV absorber has a hydroxyphenylbenzotriazole structural unit. Phenol, 2,2'-methylene-bis(6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)) which is commercially available from BASF Schweiz AG under the name Tinuvin® 360, is particularly preferred.

[0048] Films A, B, and C can be manufactured by any conventional method, such as melt (co)extrusion or solvent casting.

[0049] Preferably, the thickness of film B and / or film C is 250 to 2500 μm, more preferably 500 to 1000 μm, and most preferably 700 to 900 μm.

[0050] The polyvinyl acetals used herein are generally produced by acetalizing polyvinyl alcohol or ethylene vinyl alcohol copolymers.

[0051] The films may each contain polyvinyl acetals having different polyvinyl alcohol content, degrees of acetalization, residual acetic acid content, ethylene ratio, molecular weight, and / or different chain lengths of acetal group aldehydes.

[0052] In particular, the aldehydes used in the production of polyvinyl acetals can be linear or branched (i.e., "n" or "iso" type) containing 2 to 10 carbon atoms, which result in the corresponding linear or branched acetal group. Accordingly, polyvinyl acetals are called "polyvinyl (iso)acetals" or "polyvinyl (n)acetals".

[0053] The polyvinyl(n) acetals used in accordance with the present invention are, in particular, obtained from the reaction of at least one polyvinyl alcohol with one or more aliphatic unbranched keto compounds containing 2 to 10 carbon atoms. For this purpose, n-butyraldehyde is preferably used, and the polyvinyl acetal is polyvinyl butyral (PVB).

[0054] The film preferably contains polyvinyl acetal having polyvinyl acetate groups in a ratio of 0.1 to 20 mol%, preferably 0.5 to 3 mol%, or 5 to 8 mol%, which are identical or different in each layer.

[0055] The polyvinyl alcohol content of the polyvinyl acetal used may be 6-26% by weight, 8-24% by weight, 10-22% by weight, 12-21% by weight, 14-20% by weight, 16-19% by weight, preferably 16-21% by weight, or 10-16% by weight.

[0056] The vinyl alcohol content and vinyl acetate content of polyvinyl acetal were determined in accordance with DIN ISO 3681 (acetic acid content) and DIN ISO 53240 (PVA content).

[0057] The film used in accordance with the present invention contains at least 16% by weight, for example 16.1 to 36.0% by weight, preferably 22.0 to 32.0% by weight, and particularly 26.0 to 30.0% by weight of a plasticizer.

[0058] A suitable plasticizer can be selected from the following group: - Esters of polyhydric aliphatic or aromatic acids, for example, dialkyl adipates, for example, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, mixtures of heptyl adipate and nonyl adipate, diisononyl adipate, heptylnonyl adipate, and esters of adipic acid with ester alcohols containing alicyclic ester alcohols or ether compounds, dialkyl sebacate, for example, dibutyl sebacate, and also esters of sebacate with ester alcohols containing alicyclic ester alcohols or ether compounds, esters of phthalates, for example, butyl benzyl phthalate or bis-2-butoxyethyl phthalate.

[0059] - Esters or ethers of oligoether glycols having polyhydric aliphatic or aromatic alcohols, or one or more unbranched or branched aliphatic or aromatic substituents, such as glycerol, diglycol, triglycol, or tetraglycol, and linear or branched aliphatic or alicyclic carboxylic acids (examples of the latter group include diethylene glycol-bis-(2-ethylhexanoate), triethylene glycol-bis-(2-ethylhexanoate), triethylene glycol-bis-(2-ethylbutanoate), tetraethylene glycol-bis-n-heptanoate, triethylene glycol-bis-n-heptanoate, triethylene glycol-bis-n-hexanoate, tetraethylene glycol dimethyl ether, and / or dipropylene glycol benzoate). - Phosphate esters with aliphatic or aromatic ester alcohols, e.g., tris(2-ethylhexyl) phosphate (TOF), triethyl phosphate, diphenyl-2-ethylhexyl phosphate and / or tricresyl phosphate - Esters of citric acid, succinic acid, and / or fumaric acid.

[0060] Furthermore, the film may contain additional additives such as residual water, antioxidants, adhesion modifiers, fluorescent whitening agents or fluorescent additives, stabilizers, colorants, processing aids, inorganic nanoparticles, calcined silicic acid and / or surface-active substances.

[0061] According to the present invention, film C can first be melted over its entire surface or locally on a glass sheet by increasing the temperature together with film A, and then covered with film B. Alternatively, film C can be placed together with films A and B between two glass sheets and melted at a high temperature.

[0062] The lamination process for manufacturing laminated glass is preferably carried out by placing film C together with films A and B between two glass sheets, and then pressing the resulting layered body under pressure or reduced pressure at a high temperature to form a laminate.

[0063] To laminate the layered bodies, methods familiar to those skilled in the art can be used, whether or not pre-laminates are manufactured in advance.

[0064] The autoclave process is carried out for about 2 hours at a pressure of approximately 10–15 bar and a temperature of 100–145°C. For example, according to EP1235683B1, the vacuum bag or vacuum ring method is carried out at approximately 200 mbar and 130–145°C.

[0065] Vacuum laminators can also be used. These consist of a chamber that can be heated and evacuated, and lamination glazing can be laminated within 30 to 60 minutes. A reduced pressure of 0.01 to 300 mbar and a temperature of 100 to 200°C, especially 130 to 160°C, have proven to be of practical value.

[0066] Any or all of the films may also have a wedge-shaped thickness profile for HUD applications.

[0067] In its simplest form, film B is a commercially available PVB film, with or without an ink ribbon, and with or without a wedge-shaped thickness profile.

[0068] In a preferred embodiment of the present invention, the laminate is used such that film B faces the side that is more exposed to UV light, for example, when the laminate is used as a windshield or a window in a building, film B is used so that it faces outwards from the vehicle or building, respectively.

[0069] In a second aspect, the present invention is - A polymer and at least one film A comprising a photochromic material that exhibits photochromic coloration when exposed to radiation with wavelengths of 400 nm or less, and does not exhibit photochromic coloration at wavelengths greater than 400 nm, - A film B comprising polyvinyl acetal, at least one plasticizer, and at least one UV absorber Includes, Film B, measured in accordance with ISO 13837, has a light transmittance of 1% or less for light with wavelengths of 400 nm or less. Regarding thermoplastic intermediate layers.

[0070] In a third aspect, the present invention, in order, -A film C containing polyvinyl acetal and a plasticizer, having a light transmittance of 10% or more for light with wavelengths of 400 nm or less, as measured in accordance with ISO 13837, -A film A containing polyvinyl alcohol (PVA) and a photochromic material that exhibits photochromic coloration when exposed to radiation with wavelengths below 400 nm, and does not exhibit photochromic coloration at wavelengths above 400 nm, - Film B comprising polyvinyl acetal, at least one plasticizer, and at least one UV absorber, and having a light transmittance of 1% or less for light with a wavelength of 400 nm or less, as measured in accordance with ISO 13837. This relates to thermoplastic intermediate layers, including those mentioned above.

[0071] Examples Photochromic film A is, a) 12 g aqueous polyvinyl alcohol (PVA) solution (8.75 wt% Poval 10-98, commercially available from Kuraray Europe GmbH) b) 0.11 mL of Myglyol® 812 containing 1 mg of Reversacol® Palatinate Purple photochromic dye, Casting a nanoemulsion consisting of, Subsequently, the water was evaporated, forming a solid PVA film containing nanoscale droplets of a mixture of Myglyol® 812 and Reversacol® Palatinate Purple. The film was prepared according to US10227527B, Example 8.

[0072] The following characteristics of film A will be measured. - Thickness: 100 μm -Visible light transmittance 透明 [EN 410]>80% -Visible light transmittance 有色 [EN 410] <20% - Haze level [ASTM D1003] < 2%

[0073] Using film A, a glass laminate A having the following structure and layer order is prepared. i.2mm float glass (external side "S1") ii. 0.76mm PVB film (Trosifol® UV Extra Protect, commercially available from Kuraray Europe GmbH) iii. Film A, 0.1 mm thick, as described above. iv. 0.76mm PVB film (Trosifol® Natural UV, commercially available from Kuraray Europe GmbH) v.2mm float glass (internal side "S4")

[0074] PVB film layer ii blocks over 95% of electromagnetic radiation in the 290nm to 400nm range. PVB film layer iv transmits over 70% of electromagnetic radiation in the 360nm to 400nm range.

[0075] Exposure of the outer side S1 of glass laminate A to natural sunlight or a radiation source emitting 380 nm radiation does not have a measurable effect on the visible light transmittance of the laminate.

[0076] When the internal S4 is exposed to sunlight or a radiation source emitting radiation with a wavelength of 380 nm, its visible light transmittance decreases to less than 20%.

[0077] Furthermore, the durability of photochromic glass laminate A is significantly increased due to the described laminate structure and orientation. When glass laminate A is irradiated with a xenon lamp for 4500 hours relative to S1, the ΔE (CIE-LAB) measurement shows a value of less than 1.5 in the transparent state.

[0078] Using the same test, glass laminate B, which has a similar structure to glass laminate A, was irradiated. The only difference was the use of a standard PVB film in layer ii. This modification of the laminate structure resulted in a high ΔE of over 5.5 for the transparent state and an increase in visible light transmittance to over 20%.

Claims

1. Laminated glass for use as vehicle glazing or building glazing, comprising a first glass sheet and a second glass sheet laminated by at least one thermoplastic interlayer, wherein the thermoplastic interlayer is - A film A directed towards the inside of the vehicle or the building, comprising a polymer and a photochromic material that exhibits photochromic coloration when exposed to radiation with wavelengths of 400 nm or less, and does not exhibit photochromic coloration at wavelengths greater than 400 nm, - Facing outwards from the vehicle or the building, at least one film B comprising polyvinyl acetal, at least one plasticizer, and at least one UV absorber Includes, Film B, measured in accordance with ISO 13837, has a light transmittance of 5% or less for light with a wavelength of 400 nm or less. A radiation source having a wavelength of 400 nm or less, suitable for exciting the photochromic material in at least one film A, is arranged to enable the excitation of the photochromic material. Laminated glass.

2. The laminated glass according to claim 1, wherein the polymer in film A is polyamide, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene furanoate (PEF), polyethylene naphthalate (PEN), polyvinyl alcohol (PVA), polylactic acid (PLA), cellulose acetate, polymethyl methacrylate (PMMA), ionomer, or a combination thereof.

3. The laminated glass according to claim 2, wherein the polymer in film A contains polyvinyl alcohol, consists of polyvinyl alcohol, or is essentially made of polyvinyl alcohol.

4. The laminated glass according to claim 2 or 3, wherein the photochromic material is introduced into film A in the form of a nanoemulsion.

5. A laminated glass according to any one of claims 2 to 4, comprising a film C containing polyvinyl acetal and a plasticizer, wherein film C is disposed between film A and one of the glass sheets, and film C has a light transmittance of 5% or more for light having a wavelength of 400 nm or less, as measured in accordance with ISO 13837.

6. The laminated glass according to claim 1, wherein film A comprises polyvinyl acetal and a plasticizer.

7. The laminated glass according to claim 6, wherein the polyvinyl acetal is polyvinyl butyral.

8. The laminated glass according to claim 6 or 7, comprising a barrier film between film A and film B.

9. The laminated glass according to claim 8, wherein the barrier film comprises, consists of, or is essentially made of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyvinyl alcohol (PVA).

10. The laminated glass according to any one of claims 7 to 9, wherein the photochromic substance has a low tendency to diffuse into the polyvinyl acetal of film A.

11. The laminated glass according to any one of claims 7 to 10, wherein the at least one UV absorber has a low tendency to diffuse into the polyvinyl acetal of film B.

12. The laminated glass according to any one of claims 1 to 11, wherein the polyvinyl acetal of film B is polyvinyl butyral.

13. A laminated glass for a vehicle windshield, comprising a radiation source of light having a wavelength of 400 nm or less, according to any one of claims 1 to 12.

14. - A polymer and at least one film A comprising a photochromic material that exhibits photochromic coloration when exposed to radiation with wavelengths of 400 nm or less, and does not exhibit photochromic coloration at wavelengths greater than 400 nm, - A film B comprising polyvinyl acetal, at least one plasticizer, and at least one UV absorber Includes, Film B, measured in accordance with ISO 13837, has a light transmittance of 5% or less for light with a wavelength of 400 nm or less. Thermoplastic intermediate layer.

15. In order, - A film C containing polyvinyl acetal and a plasticizer, having a light transmittance of 5% or more for light with a wavelength of 400 nm or less, as measured in accordance with ISO 13837, - A film A containing polyvinyl alcohol (PVA) and a photochromic material that exhibits photochromic coloration when exposed to radiation with wavelengths of 400 nm or less, and does not exhibit photochromic coloration at wavelengths greater than 400 nm, - Film B comprising polyvinyl acetal, at least one plasticizer, and at least one UV absorber, and having a light transmittance of 5% or less for light with a wavelength of 400 nm or less, as measured in accordance with ISO 13837. A thermoplastic intermediate layer containing the above.

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