WO2020018310A1

WO2020018310A1 - Interface phase separation in laminate glass and methods of manufacturing thereof

Info

Publication number: WO2020018310A1
Application number: PCT/US2019/040927
Authority: WO
Inventors: Xiaoju GUO; Liying Zhang
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2018-07-19
Filing date: 2019-07-09
Publication date: 2020-01-23
Anticipated expiration: 2021-01-19

Abstract

A light-scattering laminated glass article includes a first glass layer having a first glass composition; a second glass layer having a second glass composition and fused to the first glass layer; and an inter-diffused layer disposed between the first glass layer and the second glass layer and including components of both the first glass layer and the second glass layer, such that the inter-diffused layer has a different composition or material phase than the first glass layer and the second glass layer. Also disclosed are methods for forming light-scattering laminated glass articles.

Description

INTERFACE PHASE SEPARATION IN LAMINATE GLASS AND METHODS OF

MANUFACTURING THEREOF

BACKGROUND

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 62/700,513 filed on July 19, 2018, the content of which is relied upon and incorporated herein by reference in its entirety.

1. Field

[0002] This disclosure relates to interface phase separation in laminate glass and methods of manufacturing thereof.

2. Technical Background

[0003] Glass articles, such as those described herein, may be incorporated into a wide variety of consumer and commercial electronic devices and as a result, are susceptible to incidental contact and damage during transport and/or use of the associated device. These glass articles may require enhanced strength achieved by chemical tempering, thermal tempering, and lamination.

[0004] Currently, technologies for strength-enhancing processes cannot achieve glass articles with desirable optical characteristics for use as cover glasses, glass backplanes, and the like, in display devices, especially when viewing images at non-normal angles is a consideration for a display device application.

[0005] The disclosure discloses laminated glass articles and methods for forming laminated glass articles which have improved optical characteristics.

SUMMARY

[0006] In some embodiments, a light-scattering laminated glass article comprises: a first glass layer comprising a first glass composition; a second glass layer comprising a second glass composition and fused to the first glass layer; and an inter-diffused layer disposed between the first glass layer and the second glass layer and including components of both the first glass layer and the second glass layer, wherein the inter-diffused layer has a different composition or material phase than the first glass layer and the second glass layer. [0007] In one aspect, which is combinable with any of the other aspects or embodiments, the inter-diffused layer comprises P2O5 and at least one alkaline earth metal oxide.

[0008] In one aspect, which is combinable with any of the other aspects or embodiments, the P2O5 is present at a concentration in a range of 15 wt.% and 50 wt.% and the at least one alkaline earth metal oxide is present with a total concentration in a range of 20 wt.% and 65 wt.%.

[0009] In one aspect, which is combinable with any of the other aspects or embodiments, the inter-diffused layer further comprises AI2O3, S1O2, and at least one alkali metal oxide.

[0010] In one aspect, which is combinable with any of the other aspects or embodiments, the inter-diffused layer comprises droplets.

[0011] In one aspect, which is combinable with any of the other aspects or embodiments, the droplets have a maximum dimension in a range of 100 nm to 1 pm.

[0012] In one aspect, which is combinable with any of the other aspects or embodiments, the inter-diffused layer comprises at least one of crystalline, semi-crystalline, or phase- separated bodies.

[0013] In one aspect, which is combinable with any of the other aspects or embodiments, the inter-diffused layer has a different refractive index than the first glass layer and the second glass layer.

[0014] In one aspect, which is combinable with any of the other aspects or embodiments, the first glass composition has a different coefficient thermal expansion (CTE) than the second glass composition.

[0015] In one aspect, which is combinable with any of the other aspects or embodiments, the first glass composition is an aluminophosphosilicate glass.

[0016] In one aspect, which is combinable with any of the other aspects or embodiments, the aluminophosphosilicate glass comprises P2O5 at a concentration of at least 3 mol.%.

[0017] In one aspect, which is combinable with any of the other aspects or embodiments, the second glass composition is an aluminosilicate glass.

[0018] In one aspect, which is combinable with any of the other aspects or embodiments, the aluminosilicate glass comprises at least one alkaline earth metal oxide at a total concentration of at least 2.5 mol.%.

[0019] In some embodiments, a method for forming a light-scattering laminated glass article comprises: flowing a molten first glass composition; flowing a molten second glass composition to contact the molten first glass composition such that an interface is formed between the molten first glass composition and the molten second glass composition; and inter-diffusing a portion of the molten first glass composition into the molten second glass composition and a portion of the molten second glass composition into the molten first glass composition to form a phase-separated interface.

[0020] In one aspect, which is combinable with any of the other aspects or embodiments, the first glass composition has a first strain temperature and a first softening point temperature and the second glass composition has a second strain temperature and a second softening point temperature, and the inter-diffusing comprises: heating between the lower of the first strain temperature and the second strain temperature to the higher of the first softening point temperature and second softening point temperature to form an inter-diffused interface; and cooling the inter-diffused interface to form the phase-separated interface.

[0021] In one aspect, which is combinable with any of the other aspects or embodiments, the heating is conducted at a temperature of at least l200°C for a time in a range of 0.5 hr and 5 hrs, and the cooling is conducted at a temperature in a range of 200°C to l200°C for a time in a range of 3 min to 30 min.

[0022] In one aspect, which is combinable with any of the other aspects or embodiments, the heating is conducted during the flowing of the molten second glass composition.

[0023] In one aspect, which is combinable with any of the other aspects or embodiments, the heating is conducted after the flowing of the molten second glass composition.

[0024] In one aspect, which is combinable with any of the other aspects or embodiments, the first glass composition comprises an aluminophosphosilicate glass and the second glass composition comprises an aluminosilicate glass.

[0025] In one aspect, which is combinable with any of the other aspects or embodiments, the aluminophosphosilicate glass comprises P2O5 at a concentration of at least 3 mol.%; and wherein the aluminosilicate glass comprises at least one alkaline earth metal oxide at a total concentration of at least 2.5 mol.%.

[0026] In one aspect, which is combinable with any of the other aspects or embodiments, the phase-separated interface is an inter-diffused layer comprising P2O5 and at least one alkaline earth metal oxide.

[0027] In one aspect, which is combinable with any of the other aspects or embodiments, the P2O5 is present at a concentration in a range of 15 wt.% and 50 wt.% and the at least one alkaline earth metal oxide is present with a total concentration in a range of 20 wt.% and 65 wt.%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, in which:

[0029] FIGS. 1 A and 1B illustrates a schematic cross-sectional view of a portion of a laminated glass article, according to some embodiments.

[0030] FIG. 2 illustrates a schematic of a fusion draw process for making the glass article of FIG. 1A, according to some embodiments.

[0031] FIG. 3 illustrates a schematic magnified cross-sectional view of a portion of an interface of glass layers in the laminated glass article of FIG. 1B, according to some embodiments.

[0032] FIG. 4 illustrates an image of a Glass l/Glass 3 laminate showing phase separation and devitrification, but no cracks or significant blistering potential between the two glasses, according to some embodiments.

[0033] FIG. 5 illustrates a back- scattered electron (BSE) image of a Glass l/Glass 3 laminate, according to some embodiments.

[0034] FIGS. 6A-6D illustrate energy-dispersive x-ray (EDX) spectroscopy mappings of areas collected from the sample shown in FIG. 5, according to some embodiments.

[0035] FIG. 7 illustrates a phase-separated interface of a Glass 2/Glass 3 laminate, according to some embodiments.

[0036] FIG. 8 illustrates phase-separated interface droplets of a Glass 2/Glass 3 laminate, according to some embodiments.

[0037] FIG. 9 illustrates line scan data collected across the phase-separated interface of the Glass 2/Glass 3 laminate of FIG. 8, according to some embodiments.

DETAILED DESCRIPTION

[0038] Reference will now be made in detail to exemplary embodiments which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the exemplary embodiments. It should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.

[0039] Additionally, any examples set forth in this specification are illustrative, but not limiting, and merely set forth some of the many possible embodiments of the claimed invention. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the art, are within the spirit and scope of the disclosure.

[0040] Light scattering components may used to enhance optical characteristics of laminated glass articles, such as when laminated glass articles are utilized in display devices for viewing images, including still-images or video. For example, images may be projected onto the laminated glass article from a front or back side relative to a viewer. Light scattering components may scatter the projected image so that it is viewable by the viewer. Thus, light scattering components enable the laminated glass article to be used as a projection screen (e.g., a transparent projection screen).

[0041] Also, for example, light from a display device may propagate through laminated glass articles utilized as cover glasses (i.e., towards the viewer) and the image may be enhanced by scattering the light into varying directions as the light exits the laminated glass article. In particular, image quality at non-normal viewing angles may be enhanced by the light-scattering function of the laminated glass article. In other words, light entering the laminated glass article at an angle substantially normal to a major surface of the laminated glass article can be scattered to enhance the image at non-normal viewing angles.

[0042] A glass article strengthened by lamination is formed from at least two glass compositions which have different coefficients of thermal expansion (CTE). These glass compositions are brought into contact with one another in a molten state to form the glass article, i.e., the glass compositions are fused or laminated together. As the glass

compositions cool, the difference in CTE causes compressive stresses to develop in at least one of the layers of glass, thereby strengthening the glass article. Lamination processes may also be used to impart or enhance other properties of laminated glass articles, including physical, optical, and chemical properties.

[0043] The present disclosure relates to laminated glass articles and methods for forming laminated glass articles which have improved optical characteristics. Generally, in some embodiments, a light-scattering laminated glass article includes a first glass layer comprising a first glass composition, a second glass layer comprising a second glass composition and fused to the first glass layer, and an inter-diffused layer disposed between the first glass layer and the second glass layer and having components of both the first glass layer and the second glass layer such that the inter-diffused layer has a different composition or material phase than the first glass layer and the second glass layer. In some examples, the inter-diffused layer may have a composition derived from a combination of the first glass composition and the second glass composition at the lamination interface. The inter-diffused layer may function as the light scattering component, which serves to scatter light projected onto or through the laminated glass article.

[0044] Light scattering may be accomplished by a difference in refractive index of the light-scattering component as compared with the materials of the first glass layer and the second glass layer. That is, the inter-diffused layer may have a different refractive index than that of the first glass layer or the second glass layer. Light scattering may also be affected by at least a partial reflectivity of the light-scattering component. The laminated glass articles described herein promote light scattering while having smooth outer edges and surfaces, since the inter-diffused layer is embedded between the laminated glass.

[0045] Referring now to FIGS. 1 A and 1B, a cross-sectional view of a portion of a laminated glass article 100 is schematically illustrated, according to some embodiments. While FIGS. 1 A and 1B schematically depict the laminated glass article 100 as being a laminated glass sheet, it should be understood that other configurations and form factors are contemplated and possible. For example, the laminated glass article may have a non-planar configuration such as a curved glass sheet or the like. Alternatively, the laminated glass article may be a laminated glass tube, container, or the like.

[0046] The laminated glass article 100 generally comprises a glass core layer 102 and at least one glass cladding layer l04a. In the laminated glass article 100 of FIGS. 1A and 1B, the laminated glass article comprises a pair of glass cladding layers l04a, l04b positioned on either side of the glass core layer 102. Alternatively, the laminated glass article 100 may be constructed as a bi-layer laminate, such as when one of the glass cladding layers l04a, l04b is omitted from the laminated glass article leaving a single glass cladding layer fused to the glass core layer. In some examples, laminated glass article may include at least three laminated glass layers (e.g., at least 3, at least 4, at least 5, at least 6, etc.).

[0047] The glass core layer 102 generally comprises a first surface 103 a and a second surface l03b which is opposed to the first surface l03a. A first glass cladding layer l04a is fused to the first surface 103 a of the glass core layer 102 and a second glass cladding layer l04b is fused to the second surface l03b of the glass core layer 102. Thus, the glass cladding layers l04a, l04b are fused directly to the glass core layer 102 or are directly adjacent to the glass core layer. Lamination interfaces are present at the first surface 103 a and the second surface l03b. As used herein, the“interface” refers to the meeting point of the glass core layer 102 and a glass cladding layer l04a and/or l04b.

[0048] In some examples, the glass core layer 102 or the first glass cladding layer l04a and/or the second glass cladding layer l04b may comprise an aluminophosphosilicate glass including a concentration of P2O5. In some examples, the glass core layer 102 or the first glass cladding layer l04a and/or the second glass cladding layer l04b may comprise an aluminosilicate glass including a concentration of at least one alkaline earth metal oxide.

[0049] The P2O5 oxide of the aluminophosphosilicate glass may function to extract alkaline earth components from the adjoining aluminosilicate glass to form an inter-diffused layer disposed therebetween. In some examples, the inter-diffused layer comprises phase- separated, alkaline earth-rich phosphate droplets. In some examples, the droplets may have a maximum dimension in a range of 1 nm to 5 pm, or in a range of 10 nm to 2.5 pm, or in a range of 100 nm to 1 pm, or as a distribution of sizes within any maximum dimension range. In some examples, the inter-diffused layer comprises at least one of crystalline, semi crystalline, or phase-separated bodies.

[0050] The content of P2O5 in the aluminophosphosilicate glass must be sufficient to provide enough phosphorus sources at the predetermined temperature and time to form the phase-separated inter-diffused layer. In some examples, the concentration of P2O5 may be at least 1 mol.%, or at least 2 mol.%, or at least 3 mol.%, or at least 5 mol.%, or at least 10 mol.%, or at least 15 mol.%, or at least 20 mol.% of the aluminophosphosilicate glass.

[0051] Similarly, the content of the alkaline earth metal oxides in the aluminosilicate glass must be sufficient to provide enough alkaline earth metal sources at the predetermined temperature and time to form a pronounced phase-separated inter-diffused layer. In some examples, the concentration of the alkaline earth metal oxides may be at least 1 mol.%, or at least 2 mol.%, or at least 3 mol.%, or at least 5 mol.%, or at least 10 mol.%, or at least 15 mol.%, or at least 20 mol.% of the aluminosilicate glass. In some examples, the

concentration of the alkaline earth metal oxides may be in a range of 1 mol.% and 5 mol.% of the aluminosilicate glass (e.g., 2.5 mol.% or 2.6 mol.%). The alkaline earth metal oxides may include at least one of beryllium oxide (BeO), magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), or a combination thereof. [0052] FIG. 1B illustrates inter-diffused layers l05a, l05b in some examples where the laminated glass article 100 includes a pair of glass cladding layers l04a, l04b positioned on either side of the glass core layer 102. In some examples, the inter-diffused layer comprises P2O5. In some examples, the inter-diffused layer comprises at least one alkaline earth metal oxide as disclosed herein. In some examples, the inter-diffused layer comprises P2O5 and at least one alkaline earth metal oxide as disclosed herein. In some examples, the P2O5 may be present at a concentration in a range of 15 wt.% and 50 wt.%, or in a range of 25 wt.% and 40 wt.%, or in a range of 30 wt.% and 35 wt.%. In some examples, the at least one alkaline earth metal oxide may be present with a total concentration in a range of 20 wt.% and 65 wt.%, or in a range of 30 wt.% and 55 wt.%, or in a range of 35 wt.% and 50 wt.%, or in a range of 40 wt.% and 45 wt.%. In some examples, the inter-diffused layer may include aluminum oxide (AI2O3). In some examples, the inter-diffused layer may include silicon oxide (Si0₂). In some examples, the inter-diffused layer may include at least one alkali metal oxide (e.g., lithium oxide (Li₂0), sodium oxide (Na₂0), potassium oxide (K2O), rubidium oxide (Rb₂0)). In some examples, the inter-diffused layer may include at least one of AI2O3, S1O2, or at least one alkali metal oxide. In some examples, the inter-diffused layer may include AI2O3, Si0₂, and at least one alkali metal oxide.

[0053] Also described herein is a method for forming laminated glass articles. These embodiments will be described in greater detail herein.

[0054] FIG. 2 illustrates a schematic of a fusion draw process for making the glass article of FIGS. 1 A, according to some embodiments. In some examples, a laminate fusion draw apparatus 200 for forming laminated glass articles includes an upper overflow distributor or isopipe 202 which is positioned over a lower overflow distributor or isopipe 204. The upper overflow distributor 202 includes a trough 210 into which a molten glass cladding

composition 206 is fed from a melter (not shown). Similarly, the lower overflow distributor 204 includes a trough 212 into which a molten glass core composition 208 is fed from a melter (not shown). In embodiments, the molten glass cladding composition 206 may be a first glass composition and the molten glass core composition may be a second glass composition, where the first glass composition and the second glass composition are different from one another.

[0055] As the molten glass core composition 208 fills the trough 212, it overflows the trough 212 and flows over the outer forming surfaces 216, 218 of the lower overflow distributor 204. The outer forming surfaces 216, 218 of the lower overflow distributor 204 converge at a root 220. Accordingly, the molten glass core composition 208 flowing over the outer forming surfaces 216, 218 rejoins at the root 220 of the lower overflow distributor 204 thereby forming a glass core layer 102 of a laminated glass article.

[0056] Simultaneously, the molten glass cladding compositions 206 overflows the trough 210 formed in the upper overflow distributor 202 and flows over outer forming surfaces 222, 224 of the upper overflow distributor 202. The molten glass cladding composition 206 is outwardly deflected by the upper overflow distributor 202 such that the molten glass cladding composition 206 flows around the lower overflow distributor 204 and contacts the molten glass core composition 208 flowing over the outer forming surfaces 216, 218 of the lower overflow distributor, fusing to the molten glass core composition and forming glass cladding layers l04a, l04b around the glass core layer 102.

[0057] In some examples, the molten glass core composition 208 may have an average core coefficient of thermal expansion CTE_COre which is greater than the average cladding coefficient of thermal expansion CTE_ciad of the molten glass cladding composition 206.

Accordingly, as the glass core layer 102 and the glass cladding layers l04a, l04b cool, the difference in the coefficients of thermal expansion of the glass core layer 102 and the glass cladding layers l04a, l04b cause compressive stresses to develop in the glass cladding layers l04a, l04b. The compressive stress increases the strength of the resulting laminated glass article. As used herein, the term“average coefficient of thermal expansion” refers to the average coefficient of thermal expansion of a given material or layer between 0°C and 300°C.

[0058] In some embodiments, CTE_COre and CTE_ciad differ by at least about 5x 10 ⁷ °C ', at least about 15^c 10 ⁷“C¹, at least about 25x 1 O ⁷“C¹, or at least about 30x 1 O ⁷ °C ¹.

Additionally, or alternatively, CTE_COre and CTEciad differ by at most about 100^c 10 ⁷ °C ', at most about 75x 10 ⁷“C¹, at most about 50x 10 ⁷“C¹, at most about 40x 10 ⁷“C¹, at most about 30x l0 ^{7 o}C ¹, at most about 20x l0 ^{7 o}C ¹, or at most about l0x l0 ^{7 o}C ¹. The delta between the CTEcore and CTEciad strengthens the glass laminate by forming compression stresses in the clad layer. In some embodiments, CTEciad is at most about 66 ^c 10 ⁷ °C ', at most about 55x l0 ^{7 o}C ¹, at most about 50x l0 ^{7 o}C ¹, at most about 40x 1 O ⁷“C¹, or at most about 35 x lO ⁷ °C ' . Additionally, or alternatively, CTEciad is at least about 25 ^c 10 ⁷ °C ', or at least about 30^c 10 ⁷ °C ¹. Additionally, or alternatively, CTE_core is at least about 40 ^c 10 ⁷“C¹, at least about 50^c 10 ⁷“C¹, at least about 55x 10 ⁷“C¹, at least about 65x 10 ⁷“C¹, at least about 70x 10 ⁷ °C ¹, at least about 80x 10 ⁷“C¹, or at least about 90x 10 ⁷ °C ¹. Additionally, or alternatively, CTE_COre is at most about 110^c 10 ⁷“C¹, at most about 100^c 10⁷“C¹, at most about 90^c 10⁷“C¹, at most about 75x 10 ⁷“C¹, or at most about 70x 10⁷ °C^'1.

[0059] While FIG. 2 schematically depicts an apparatus for forming planar laminated glass articles such as sheets or ribbons, other geometrical configurations are also possible, such as cylindrical laminated glass articles.

[0060] Now referring to FIG. 3, in embodiments, the laminated glass article 100 comprises at least one inter-diffused layer l05a comprising light-scattering members 110 (e.g., droplets) and disposed between the glass core layer 102 and at least one of the glass cladding layers l04a, l04b (i.e., at the interface). The light-scattering members 110 may be positioned along substantially the entire interface of the glass core layer 102 and the glass cladding layer l04a. As shown in FIG. 3, the light-scattering members 110 may be substantially spherical in shape. However, in other embodiments, the light-scattering members 110 may have other shapes or form factors, such as irregularly shaped bodies having rounded or substantially flat surfaces, including particles comprising sharp angular features.

[0061] The light-scattering members 110 may have varying sizes. In one embodiment, each light-scattering member 110 may have a maximum dimension in a range of 1 nm to 5 pm (e.g., from 5 nm to 4.5 pm, or from 10 nm to 4.0 pm, or from 15 nm to 3.5 pm, or from 20 nm to 3.0 pm, or from 25 nm to 2.5 pm, or from 30 nm to 2.0 pm, or from 35 nm to 1.5 pm, or from 40 nm to 1.0 pm, or from 45 nm to 500 nm, or from 50 nm to 250 nm), or in a range of 10 nm to 2.5 pm (e.g., from 15 nm to 2.0 pm, or from 20 nm to 1.5 pm, or from 25 nm to 1.0 pm, or from 30 nm to 500 nm, or from 35 nm to 250 nm, or from 40 nm to 125 nm, or from 45 nm to 100 nm, or from 50 nm to 75 nm), or in a range of 100 nm to 1 pm (e.g., from 150 nm to 900 nm, or from 200 nm to 800 nm, or from 250 nm to 700 nm, or from 300 nm to 700 nm, or from 350 nm to 600 nm, or from 400 nm to 500 nm). However, other embodiments are contemplated herein that utilize light-scattering members 110 which have a maximum dimension even greater than 5 pm.

[0062] As used herein, the“maximum dimension” refers to the greatest distance between surfaces of an individual light-scattering member 110 through the light-scattering member 110. For example, the maximum dimension of a spherical light-scattering member 110 is the diameter of the sphere. The“average maximum dimension” refers to the average of the maximum dimensions of all light-scattering members 110 of a laminated glass article 100.

[0063] The light-scattering members 110 may comprise a composition or phase different from the other portions of the laminated glass article 100. In some examples, the light- scattering members 110 may comprise solids (e.g., particles) and/or gasses (oxygen, etc.), void spaces, droplets, or a combination thereof. Moreover, the light-scattering members 110 may have different compositions or phases from one another.

[0064] In some examples, the inter-diffused layer may be substantially flat at the lamination interface. The inter-diffused layer may be formed from an inter-diffusion of the glass core layer 102 and one or more of the glass cladding layers l04a, l04b. The inter- diffused layer formed is situated at the interface of the glass core layer 102 and one or more of the glass cladding layers l04a, l04b. The inter-diffused layer may be at least as thick as the maximum dimension of the largest light-scattering members 110 disposed therein. In some examples, an inter-diffused layer may comprise light-scattering members 110 (i.e., the light-scattering members 110 distinguishable from matrix 112). In some examples, individual light-scattering members may not be distinguishable within a matrix of the inter- diffused layer. For example, crystal growth may be present throughout the inter-diffused layer and individual nucleation sites for crystallization growth may create light-scattering members within the inter-diffused layer.

[0065] The light-scattering members 110 may have varying sizes and shapes, such that they interact differently with light of different wavelengths. Such varying sizes and/or shapes can enable an image comprising a plurality of colors (e.g., a full color image) to be projected onto the laminated glass article and visible by the viewer. In some examples, light-scattering members have a size distribution suitable to scatter light over a portion of or substantially the entire visible spectrum (e.g., light in a range of 400 nm to 700 nm). The density of light scattering members may vary per surface area of the interface. However, methods for producing laminated glass articles as described herein may be capable of controlling the size, shape, size distribution, and/or relative amount of the light-scattering members.

[0066] The material of the inter-diffused layer may have a refractive index that is different from the materials of the glass core layer 102 and glass cladding layers l04a, l04b. For example, the refractive index of the material of the inter-diffused layer may be at least about 1%, or at least about 2%, or at least about 3%, or at least about 4%, or at least about 5%, or at least about 10%, or at least about 20%, or at least about 30%, or at least about 40%, or at least about 50% different (i.e., greater than or less than) than the refractive index of the materials of the glass core layer 102 or the glass cladding layers l04a, l04b.

[0067] In some examples, the inter-diffused layer may comprise one or more crystalline, semi-crystalline, or phase separated bodies disposed at the interface of the glass core layer 102 and one or more of the glass cladding layers l04a, l04b. The crystalline, semi crystalline, or phase separated bodies may form discrete light-scattering members 110, as depicted in FIG. 3, or may be formed as a uniform layer at the interface of the laminated glass layers. The crystalline, semi-crystalline, or phase separated bodies may be caused by the inter-diffusion of materials present in the molten glass cladding compositions 206 and the molten glass core composition 208. In some examples, the crystalline, semi-crystalline, or phase separated bodies may comprise ceramic or glass-ceramic materials. The crystalline or semi-crystalline bodies described herein may be at least partially devitrified, meaning that at least some degree of organized internal structure is associated with the crystalline or semi crystalline bodies. Phase separated materials may have a phase (e.g., an amorphous phase or glass phase) which is different from the surrounding glass composition.

[0068] In some examples, the light-scattering member may be present at locations other than the interface between the core layer and the cladding layers. For example, a layer of the glass article (e.g., the core layer or the cladding layer) can be phase separated to form the light-scattering member. Such a glass article with a phase separated layer (with or without additional light-scattering members at the core/clad interface) may be used, for example, as a transparent projection screen. In some examples, the light-scattering member can be restricted to the interface between the core layer and the cladding layers. For example, the core layer and/or the cladding layer can be substantially free of light-scattering members at outer surfaces thereof, remote from the interface.

[0069] In one embodiment, nucleation sites may be generated during the fusion lamination process due to the fusing of the two glasses at high temperatures. The nucleation sites may allow devitrification at the interfaces of the glass core layer 102 and the glass cladding layers l04a, l04b. Devitrification may occur during the fusion process or in one or more subsequent heat treatments following formation of the glass laminate.

[0070] In some examples, to form the crystalline or semi-crystalline bodies, materials at the interface of the glass core layer 102 and/or the glass cladding layers l04a, l04b form an inter-diffused layer comprising an intermixed composition which is crystallizable. The intermixed composition may be crystallized by heating which may occur while the glass is being laminated in the fusion draw process. In some examples, additional heat treatments may be used to crystallize the intermixed composition after formation of the glass laminate. Additionally, heat treatments may be used to form the intermixed composition, where the heat treatment promotes diffusion and mixing of the components of the glass core layer 102 and the glass cladding layers l04a, l04b at the interface. For example, a first heat treatment may serve to form the intermixed composition and a second heat treatment may at least partially crystallize the intermixed composition. In some examples, an electrical potential in the molten glass cladding composition 206 and/or the molten glass core composition 208 may be utilized to form the intermixed composition.

[0071] In some examples, the intermixed composition of the inter-diffused layer may have a higher liquidus temperature than the materials of glass core layer 102 and the glass cladding layers l04a, l04b. For example, the liquidus temperature of the intermixed composition of the inter-diffused layer may be at least about 10% higher, or at least about 20% higher, or at least about 30% higher, or at least about 40% higher, or at least about 50% higher than the liquidus temperature of glass core layer 102 and/or the glass cladding layers l04a, l04b. Without being bound by theory, it is believed that relatively high liquidus temperature of the intermixed composition allows for the intermixed composition to be devitrified and/or phase separated in subsequent heating steps, or during the fusion lamination process. In some examples, the intermixed composition may have a devitrification temperature in the range of the forming temperature of the glass core layer 102 and/or the glass cladding layers l04a, l04b. A devitrified phase may form in the intermixed composition at the temperature corresponding to the viscosity of the glass core layer 102 and/or the glass cladding layers l04a, l04b at their forming temperatures. Typical viscosity of glass at a fusion drawn forming temperature may be in a range of 35,000 P and 300,000 P.

[0072] Glass compositions for the glass core layer 102 and the glass cladding layers l04a, l04b can be chosen to allow for the intermixed composition to have a higher liquidus temperature than the glass core layer 102 and the glass cladding layers l04a, l04b. For example, the mixture of the glass compositions of the glass core layer 102 and the glass cladding layers l04a, l04b may have a higher liquidus temperature than either the glass core layer 102 or the glass cladding layers l04a, l04b when particular glass compositions are selected.

[0073] In some examples, an aluminophosphosilicate glass and an aluminosilicate glass are utilized as the glass core layer 102 and the glass cladding layers l04a, l04b, respectively, or vice versa. However, it should be understood that many combinations of glass compositions may result in increased liquidus temperature, and any suitable combination of glass compositions is contemplated herein. In some examples, a first glass may comprise

Forsterite as the liquidus phase and is laminated with a second glass, having a lower MgO activity and therefore, a lower MgO diffusivity. Therefore, MgO from the first glass will uphill diffuse toward the interface of the first and second glasses and increase the liquidus temperature of the interface compositions. Either of the first and second glasses may be an aluminophosphate glass, an aluminoborosilicate glass, or an aluminosilicate glass.

EXAMPLES

[0074] The embodiments described herein will be further clarified by the following example. A laminated glass sample was formed from a first group glass— e.g., glass 1 or glass 2— having compositions Cl and C2, respectively, and a second group glass— e.g., glass 3— having a composition C3. Compositions Cl to C3 and associated properties are shown in Table 1. Compositions Cl and C2 had a relatively high proportion of B203 (“boron-rich”) and composition C3 had a relatively high proportion of P205 (“phosphorus-rich”). As used herein, the term“rich” is a relative term that depends on the concentration of the particular component in different glass layers.

Table 1 [0075] In one example, the laminated glass sample may be formed using the apparatus of FIG. 2. Thus, a molten first glass composition (e.g., one of Cl or C2, or C3) is flown and a molten second glass composition (e.g., C3, or one of Cl or C2) is flown to contact the molten first glass composition such that an interface is formed between the molten first glass composition and the molten second glass composition. The first glass composition may have a first strain temperature, a first softening point temperature, a first annealing temperature, and a first glass transition temperature, and the second glass composition may have a second strain temperature, a second softening point temperature, a second annealing temperature, and a second glass transition temperature.

[0076] As used herein, the“strain temperature” describes a temperature at which the glass achieves a viscosity of -10¹⁴ Poise to -10¹⁵ Poise. At this viscosity, the glass will hold its shape because it is a solid in practical terms and the movement of glass molecules has reached a point where no more strain may be introduced into the glass. As used herein, “softening point temperature” describes a temperature at which the glass achieves a viscosity of -10⁷ Poise to -10⁸ Poise. At this viscosity, the glass softens sufficiently to be worked. As used herein, the“annealing temperature” describes a temperature at which the glass achieves a viscosity of -10¹³ Poise and the“glass transition temperature” describes a temperature at which the glass achieves a viscosity of -10¹² Poise.

[0077] Thereafter, the fused article is heated between the lower of the first strain temperature and the second strain temperature to the higher of the first softening point temperature and second softening point temperature to form an inter-diffused interface. In one example, the heating is conducted at a temperature of at least l200°C for a time in a range of 0.5 hr and 5 hrs. In one example, the heating is conducted as a two-step process, with a first step of heating between the lower of the first strain temperature and the second strain temperature to one of the annealing temperature (first or second) or glass transition temperature (first or second), followed by a second heating step to the higher of the first softening point temperature and second softening point temperature. In some examples, the heating is conducted during the flowing of the molten second glass composition. In some examples, the heating is conducted after the flowing of the molten second glass composition.

[0078] As explained above, the P2O5 oxide of Cl or C2 may function to extract alkaline earth components from the adjoining C3 to form an inter-diffused layer disposed

therebetween. In some examples, the inter-diffused layer comprises phase-separated, alkaline earth-rich phosphate droplets. The content of P2O5 in the Cl or C2 glass are sufficient to provide enough phosphorus sources at the predetermined temperature and time to form the phase-separated inter-diffused layer. Likewise, the content of the alkaline earth metal oxides in the C3 glass are sufficient to provide enough alkaline earth metal sources at the

predetermined temperature and time to form a pronounced phase-separated inter-diffused layer.

[0079] The alkali metal oxide in Cl or C2 diffuses toward the C3 glass, while the alkaline earth metal oxide in C3 migrates in the opposite direction toward the Cl or C2 glass to provide alkaline earth components and form phosphate phase separation droplets in the interface.

[0080] After the step of heating, the inter-diffused interface may be cooled at a temperature in a range of 200°C to l200°C for a time in a range of several minutes to 30 minutes to form the phase-separated interface comprising a portion of the molten first glass composition and a portion of the molten second glass composition. In other words, phase separation occurs— between the light-scattering member and glass matrix— after the confluence of the two glasses during the cooling process such that the inter-diffused layer comprises at least P2O5 of C1/C2 and alkaline earth metal oxides of C3.

[0081] In some examples, the cooling may also allow for compression stress to be built-in to C3 due to the CTE mismatch between C3 and either Cl or C2, thereby producing a strengthened glass product without a requirement for an ion-exchanging or tempering post treatment. That is, because the CTE of C3 is lower than the CTE of Cl or C2, the cooling step allows for both a stress profile to be built in the laminate article (specifically in C3), as well as achieving phase separation in the interface.

[0082] Table 2 describes the composition of the light-scattering members and matrix of the inter-diffused layer, according to some examples. Without being bound by theory, it is believed that the immiscible phosphorus-rich liquid separates from the silicate melt and forms droplets. When the glass forming temperature and glass composition fall within the immiscible dome of the silica-rich and phosphorus-rich liquids, phase separation occurs during glass formation.

Table 2

[0083] FIGS. 4 to 6D illustrate images of a phase-separated Glass 1 /Glass 3 laminate sample. The sample was fused in platinum boat. Specifically, FIG. 4 is an image of a Glass l/Glass 3 laminate showing phase separation and devitrification, but no cracks or significant blistering potential between the two glasses, after a heat treatment of l200°C for about 2 hrs, according to some embodiments. FIG. 5 is a back- scattered electron (BSE) image of the Glass l/Glass 3 laminate of FIG. 4. Back-scattered electrons (BSE) consist of high-energy electrons originating in an electron beam, that are reflected or back-scattered out of the sample interaction volume by elastic scattering interactions with the sample atoms. Heavy elements (high atomic number) backscatter electrons more strongly than light elements (low atomic number) and appear brighter in the image. Thus, BSE are used to detect contrast between areas with different chemical compositions. FIG. 5 shows the crystallization with the imprinted platinum grain structure, where the platinum surface provides crystal nucleation sites.

[0084] FIGS. 6A-6D illustrate energy-dispersive x-ray (EDX) spectroscopy mappings of areas collected from the sample shown in FIG. 5. EDX is an analytical technique used for the elemental analysis or chemical characterization and relies on an interaction of X-ray excitation with the sample, whereby each element has a unique atomic structure allowing a unique set of peaks on its electromagnetic emission spectrum. FIGS. 6A to 6D shows the presence of elemental phosphorus (FIG. 6A), magnesium (FIG. 6B), strontium (FIG. 6C), and silicon (FIG. 6D) in the inter-diffused layer. For the phosphorus, magnesium, and strontium, the brightest areas of contract are seen in the light-scattering members due to the higher degrees of concentrations disposed therein. In other words, there is a significantly greater amount of these elements in the light-scattering members than in the glass matrix, Glass 1, or Glass 3. For silicon, the concentration is more evenly spread throughout Glass 1, Glass 3 and the glass matrix.

[0085] FIGS. 7 to 9 illustrate images of a phase-separated interface Glass 2/Glass 3 laminate. Specifically, FIG. 7 illustrates a phase separation observed in Glass 3 in a Glass 2/Glass 3 laminate whereby phase separation droplets are observed at a tip of diffusion front (see also FIG. 5, which shows the approximate area of the sample represented by the white box). Phase separation may also occur further from the interface. Moreover, similar to image of FIG. 4 for the Glass l/Glass 3 pair, FIG. 8 shows phase separation and devitrification between Glass 2/Glass 3 after a heat treatment of l200°C for about 2 hrs, according to some embodiments. The line extending through the droplets represents a line scan chemical composition analysis across the phase-separated interface, with the data shown in FIG. 9. As is seen in FIG. 9, three distinct segments are observed across the linear scale that correspond to the three droplets of FIG. 8 through which the line scan was conducted. In each segment, an elevated amount of Na oxide, Sr oxide, P oxide, and Mg oxide is seen. Without being bound by theory, it is believed this indicates that the P2O5 of Glass 2 may function to extract alkaline earth components from the adjoining Glass 3 to form an inter- diffused layer disposed therebetween and comprising the light-scattering members (i.e., phase-separated, alkaline earth-rich phosphate droplets).

[0086] The glass articles described herein can be incorporated into vehicles such as automobiles, boats, and airplanes (e.g., glazing such as windshields, windows or sidelites, mirrors, pillars, side panels of a door, headrests, dashboards, consoles, or seats of the vehicle, or any portions thereof), architectural fixtures or structures (e.g., internal or external walls of building, and flooring), appliances (e.g., a refrigerator, an oven, a stove, a washer, a dryer, or another appliance), consumer electronics (e.g., televisions, laptops, computer monitors, and handheld electronics such as mobile phones, tablets, and music players), furniture, information kiosks, retail kiosks, and the like. For example, the glass articles described herein can be used in display and/or touch panel applications, whereby the glass article can enable a display and/or touch panel with desired attributes of the glass article such as light scattering, mechanical strength, etc. In some examples, such displays can comprise projection displays. For example, the glass article comprises light scattering features for displaying an image projected thereon.

[0087] In some examples, a display comprising a glass article described herein is at least partially transparent to visible light. Ambient light (e.g., sunlight) can make the display image difficult or impossible to see when projected on such a display. In some examples, the display, or portion thereof on which the display image is projected can include a darkening material such as, for example, an inorganic or organic photochromic or electrochromic material, a suspended particle device, and/or a polymer dispersed liquid crystal. Thus, the transparency of the display can be adjusted to increase the contrast of the display image. For example, the transparency of the display can be reduced in bright sunlight by darkening the display to increase the contrast of the display image. The adjustment can be controlled automatically (e.g., in response to exposure of the display surface to a particular wavelength of light, such as ultraviolet light, or in response to a signal generated by a light detector, such as a photoeye) or manually (e.g., by a viewer).

[0088] The glass articles described herein can be used for a variety of applications including, for example, for cover glass or glass backplane applications in consumer or commercial electronic devices including, for example, LCD, LED, microLED, OLED, and quantum dot displays, computer monitors, and automated teller machines (ATMs); for touch screen or touch sensor applications, for portable electronic devices including, for example, mobile telephones, personal media players, and tablet computers; for integrated circuit applications including, for example, semiconductor wafers; for photovoltaic applications; for architectural glass applications; for automotive or vehicular glass applications including, for example, glazing and displays; for commercial or household appliance applications; for lighting or signage (e.g., static or dynamic signage) applications; or for transportation applications including, for example, rail and aerospace applications.

[0089] Thus, as presented herein, this disclosure relates to laminated glass articles and methods for forming laminated glass articles which have improved optical characteristics. More particularly, the present application provides a light-scattering laminated glass article with a phase-separated interface disposed between two glasses such that the interface has components of both the first glass layer and the second glass layer. The inter-diffused layer may have a composition derived from a combination of the first glass composition and the second glass composition at the lamination interface, but may still have a composition or material phase different than the first glass layer and the second glass layer.

[0090] As utilized herein, the terms“approximately,”“about,”“substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

[0091] As utilized herein,“optional,”“optionally,” or the like are intended to mean that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event or circumstance occurs and instances where it does not occur. The indefinite article“a” or“an” and its corresponding definite article“the” as used herein means at least one, or one or more, unless specified otherwise.

[0092] References herein to the positions of elements (e.g.,“top,”“bottom,”“above,” “below,” etc.) are merely used to describe the orientation of various elements in the

FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0093] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for the sake of clarity.

[0094] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claimed subject matter. Accordingly, the claimed subject matter is not to be restricted except in light of the attached claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A light-scattering laminated glass article comprising:

a first glass layer comprising a first glass composition;

a second glass layer comprising a second glass composition and fused to the first glass layer; and

an inter-diffused layer disposed between the first glass layer and the second glass layer and including components of both the first glass layer and the second glass layer,

wherein the inter-diffused layer has a different composition or material phase than the first glass layer and the second glass layer.

2. The light-scattering laminated glass article of claim 1, wherein the inter-diffused layer comprises P2O5 and at least one alkaline earth metal oxide.

3. The light-scattering laminated glass article of claim 2, wherein the P2O5 is present at a concentration in a range of 15 wt.% and 50 wt.% and the at least one alkaline earth metal oxide is present with a total concentration in a range of 20 wt.% and 65 wt.%.

4. The light-scattering laminated glass article of claim 2 or claim 3, wherein the inter- diffused layer further comprises AI2O3, S1O2, and at least one alkali metal oxide.

5. The light-scattering laminated glass article of any one of claims 2-4, wherein the inter-diffused layer comprises droplets.

6. The light-scattering laminated glass article of claim 5, wherein the droplets have a maximum dimension in a range of 100 nm to 1 pm.

7. The light-scattering laminated glass article of any one of claims 1-6, wherein the inter-diffused layer comprises at least one of crystalline, semi -crystalline, or phase-separated bodies.

8. The light-scattering laminated glass article of any one of claims 1-7, wherein the inter-diffused layer has a different refractive index than the first glass layer and the second glass layer.

9. The light-scattering laminated glass article of any one of claims 1-8, wherein the first glass composition has a different coefficient thermal expansion (CTE) than the second glass composition.

10. The light-scattering laminated glass article of any one of claims 1-9, wherein the first glass composition is an aluminophosphosilicate glass.

11. The light-scattering laminated glass article of claim 10, wherein the

aluminophosphosilicate glass comprises P2O5 at a concentration of at least 3 mol.%.

12. The light-scattering laminated glass article of any one of claims 1-11, wherein the second glass composition is an aluminosilicate glass.

13. The light-scattering laminated glass article of claim 12, wherein the aluminosilicate glass comprises at least one alkaline earth metal oxide at a total concentration of at least 2.5 mol.%.

14. A method for forming a light-scattering laminated glass article, the method comprising:

flowing a molten first glass composition;

flowing a molten second glass composition to contact the molten first glass composition such that an interface is formed between the molten first glass composition and the molten second glass composition; and

inter-diffusing a portion of the molten first glass composition into the molten second glass composition and a portion of the molten second glass composition into the molten first glass composition to form a phase-separated interface.

15. The method of claim 14, wherein: the first glass composition has a first strain temperature and a first softening point temperature and the second glass composition has a second strain temperature and a second softening point temperature, and

the inter-diffusing comprises:

heating between the lower of the first strain temperature and the second strain temperature to the higher of the first softening point temperature and second softening point temperature to form an inter-diffused interface; and

cooling the inter-diffused interface to form the phase-separated interface.

16. The method of claim 15, wherein the heating is conducted at a temperature of at least l200°C for a time in a range of 0.5 hr and 5 hrs, and the cooling is conducted at a temperature in a range of 200°C to l200°C for a time in a range of 3 min to 30 min.

17. The method of claim 15 or claim 16, wherein the heating is conducted during the flowing of the molten second glass composition.

18. The method of any one of claims 15-17, wherein the heating is conducted after the flowing of the molten second glass composition.

19. The method of any one of claims 14-18, wherein the first glass composition comprises an aluminophosphosilicate glass and the second glass composition comprises an

aluminosilicate glass.

20. The method of claim 19, wherein the aluminophosphosilicate glass comprises P2O5 at a concentration of at least 3 mol.%; and wherein the aluminosilicate glass comprises at least one alkaline earth metal oxide at a total concentration of at least 2.5 mol.%.

21. The method of any one of claims 14-20, wherein the phase-separated interface is an inter-diffused layer comprising P2O5 and at least one alkaline earth metal oxide.

22. The method of claim 21, wherein the P2O5 is present at a concentration in a range of 15 wt.% and 50 wt.% and the at least one alkaline earth metal oxide is present with a total concentration in a range of 20 wt.% and 65 wt.%.