Scratch and mar resistant laminated glass article
阅读说明：本技术 耐刮擦且耐损伤的层合玻璃制品 (Scratch and mar resistant laminated glass article ) 是由 蒂莫西·迈克尔·格罗斯 沙琳·玛丽·史密斯 于 2020-03-19 设计创作，主要内容包括：公开耐刮擦且耐损伤的层合玻璃制品。根据一个方面,所述层合玻璃制品可包括玻璃芯层和至少一个玻璃包覆层,所述玻璃芯层由芯玻璃组合物形成并且包括芯玻璃弹性模量E-(C),并且所述至少一个玻璃包覆层直接融合至所述玻璃芯层。所述至少一个玻璃包覆层可由不同于所述芯玻璃组合物的可离子交换的包覆玻璃组合物形成,并且包括包覆玻璃弹性模量E-(CL)。所述层合玻璃制品可具有总厚度T,并且所述至少一个玻璃包覆层具有厚度T-(CL),所述厚度T-(CL)大于或等于30％的总厚度T。E-(C)可比E-(CL)大至少5％。(A laminated glass article that is scratch and mar resistant is disclosed. According to one aspect, the laminated glass article may include a glass core layer formed from a core glass composition and including a core glass elastic modulus E and at least one glass cladding layer C And the at least one glass cladding layer is directly fused to the glass core layer. Said toAt least one glass cladding layer may be formed from an ion-exchangeable cladding glass composition different from the core glass composition and including a cladding glass elastic modulus E CL . The laminated glass article can have a total thickness T and the at least one glass cladding layer has a thickness T CL Said thickness T CL Greater than or equal to 30% of the total thickness T. E C Comparable E CL At least 5% greater.)
1. A laminated glass article comprising:
a glass core layer formed from a core glass composition and comprising a core glass elastic modulus EC(ii) a And
at least one glass cladding layer directly fused to the glass core layer, the at least one glass cladding layer being formed from an ion-exchangeable cladding glass composition different from the core glass composition, the at least one glass cladding layer comprising a cladding glass elastic modulus ECLWherein:
the laminated glass article has a total thickness T and the at least one glass cladding layer has a thickness TCLSaid thickness beingDegree TCLGreater than or equal to 30% of the total thickness T; and is
ECRatio ECLAt least 5% greater.
2. The laminated glass article of claim 1, wherein ECLLess than or equal to 76.5 GPa.
3. The laminated glass article of claim 2, wherein ECLGreater than or equal to 60 GPa.
4. The laminated glass article of claim 1, wherein ECAnd ECLThe difference therebetween is greater than or equal to 5 GPa.
5. The laminated glass article of claim 1, wherein the thickness T of the at least one glass cladding layerCLGreater than or equal to 35% of the total thickness T.
6. The laminated glass article of claim 1, wherein the core refractive index n of the glass core layerCA cladding refractive index n greater than the at least one glass cladding layerCL。
7. The laminated glass article of claim 6, wherein the clad refractive index nCLGreater than or equal to 1.45 and less than or equal to 1.55.
8. The laminated glass article of claim 1, wherein the at least one glass cladding layer comprises a first glass cladding layer and a second glass cladding layer, wherein:
the first glass cladding layer is directly fused to the first surface of the glass core layer; and is
The second glass cladding layer is directly fused to a second surface of the glass core layer, the second surface being opposite the first surface of the glass core layer.
9. The laminated glass article of claim 1, wherein:
the glass core layer has a core coefficient of thermal expansion CTE from 20 ℃ to 300 ℃C；
The at least one glass cladding layer has a cladding coefficient of thermal expansion CTE from 20 ℃ to 300 ℃CL(ii) a And is
CTECGreater than or equal to CTECL。
10. The laminated glass article of claim 9, wherein the laminated glass article has a intrinsic CTE thereinCAnd CTECLThe surface compressive stress caused by the difference between the above ranges is 10MPa or more and 100MPa or less.
11. The laminated glass article of claim 10, wherein the laminated glass article has an intrinsic CTECAnd CTECLA depth of compression caused by the difference therebetween, the depth of compression being greater than or equal to 20% of the total thickness T.
12. The laminated glass article of claim 1, wherein the glass core layer is formed from an ion-exchangeable core glass composition.
13. The laminated glass article of claim 12, wherein:
the glass core layer is exposed at an edge of the laminated glass article; and is
The glass core layer includes a surface compressive stress and a depth of compression at the edge of the laminated glass article.
14. The laminated glass article of claim 1, wherein the laminated glass article is ion-exchange strengthened such that the laminated glass article comprises a compressive stress region due to ion-exchange extending from a surface of the at least one glass cladding layer and into the total thickness T of the laminated glass article to a depth of compression DOC.
15. The laminated glass article of claim 14, wherein:
the laminated glass article has a surface compressive stress CS at the surface of the at least one glass cladding layer due to ion exchange0(ii) a And is
The depth of compression DOC due to ion exchange is less than or equal to 30% of the thickness T of the at least one glass cladding layerCL。
16. The laminated glass article of claim 14, wherein:
the glass core layer has a core coefficient of thermal expansion CTE from 20 ℃ to 300 ℃C；
The at least one glass cladding layer has a cladding coefficient of thermal expansion CTE from 20 ℃ to 300 ℃CL(ii) a And is
CTECGreater than or equal to CTECL。
17. The laminated glass article of claim 14, wherein Na in the at least one glass cladding layer2The concentration of O decreases from the surface of the at least one glass cladding layer, is minimal at an intermediate point within the thickness of the at least one glass cladding layer, and increases from the intermediate point toward an interfacial layer located between the at least one glass cladding layer and the glass core layer.
18. The laminated glass article of claim 14, wherein the weight gain due to ion exchange strengthening is less than 0.5%.
19. The laminated glass article of claim 14, wherein the laminated glass article has a Knoop scratch initiation threshold (Knoop scratch initiation threshold) of greater than or equal to 2N and less than or equal to 8N.
20. The laminated glass article of claim 1, comprising a surface dynamic strength of greater than or equal to 400N.
21. The laminated glass article of claim 1, comprising an edge dynamic strength of greater than or equal to 200N.
22. A laminated glass article comprising:
a glass core layer formed from an ion-exchangeable core glass composition and comprising a core refractive index nCAnd a core coefficient of thermal expansion CTE from 20 ℃ to 300 ℃C(ii) a And
at least one glass cladding layer directly fused to the glass core layer, the at least one glass cladding layer formed from an ion-exchangeable cladding glass composition different from the ion-exchangeable core glass composition, the at least one glass cladding layer comprising a cladding refractive index nCLAnd a coating coefficient of thermal expansion CTE from 20 ℃ to 300 ℃CLWherein:
the laminated glass article has a total thickness T and the at least one glass cladding layer has a thickness TCLSaid thickness TCLGreater than or equal to 30% of the total thickness T;
the core refractive index n of the glass core layerCThe cladding refractive index n being greater than the at least one glass cladding layerCL(ii) a And is
CTECGreater than or equal to CTECL。
23. The laminated glass article of claim 22, wherein the clad refractive index nCLGreater than or equal to 1.45 and less than or equal to 1.55.
24. The laminated glass article of claim 22, wherein the laminated glass article has a intrinsic CTE thereinCAnd CTECLThe surface compressive stress caused by the difference between the above ranges is 10MPa or more and 100MPa or less.
25. The laminated glass article of claim 24, wherein the laminated glass article comprisesThe laminated glass article has a intrinsic CTECAnd CTECLA depth of compression caused by the difference therebetween, the depth of compression being greater than or equal to 20% of the total thickness T.
26. The laminated glass article of claim 22, wherein the laminated glass article has a knoop scratch initiation threshold greater than or equal to 2N and less than or equal to 8N.
27. The laminated glass article of claim 22, wherein:
the laminated glass article is ion-exchange strengthened,
surface compressive stress CS at the surface of the at least one glass cladding layer due to ion exchange0Is greater than or equal to 200 MPa; and is
A depth of compression DOC due to ion exchange of less than or equal to 20% of the thickness T of the at least one glass cladding layerCL。
28. The laminated glass article of claim 22, comprising a surface dynamic strength of greater than or equal to 400N.
29. The laminated glass article of claim 22, comprising an edge dynamic strength of greater than or equal to 200N.
Technical Field
The present description relates generally to laminated glass articles and, more particularly, to laminated glass articles that are resistant to scratching and drop-induced damage.
Background
Glass articles (e.g., cover glasses, glass backsheets, etc.)) have been used in both consumer and commercial electronic devices such as LCD and LED displays, computer screens, Automated Teller Machines (ATMs), and the like. Some of these glass articles may include a "touch" function, which requires the glass article to be in contact with various objects including a user's finger and/or a stylus device, and thus, the glass must be strong enough to withstand normal contact without damage, such as scratching. In fact, scratches introduced into the surface of the glass article may reduce the strength of the glass article, as the scratches may become initiation points for cracks that lead to catastrophic damage to the glass.
Also, such glass articles may be incorporated into portable electronic devices such as mobile phones, personal media players, laptop computers, and tablet computers. Glass articles incorporating these devices may be damaged by intense impact during transportation and/or use of the associated device. Strong impact damage may include damage caused by dropping the device, for example. Such damage may lead to glass degradation.
Thus, there is a need for alternative glass articles that are both scratch resistant and drop induced damage resistant.
Disclosure of Invention
According to the first aspect a1, the laminated glass article includes a glass core layer formed from a core glass composition and including a core glass elastic modulus EC. At least one glass cladding layer may be directly fused to the glass core layer, the at least one glass cladding layer being formed from an ion exchangeable cladding glass composition different from the core glass composition, the at least one glass cladding layer comprising a cladding glass elastic modulus ECL. The laminated glass article can have a total thickness T and the at least one glass cladding layer has a thickness TCLThickness TCLGreater than or equal to 30% of the total thickness T. ECComparable ECLAt least 5% greater.
A second aspect a2 includes the laminated glass article of aspect a1, wherein ECLLess than or equal to 76.5 GPa.
The third aspect A3 includes the laminated glass article of any one of a1 or a2, wherein ECLGreater than or equal to 60 GPa.
A fourth aspect a4 includes the laminated glass article of any one of a1 to A3, wherein ECAnd ECLThe difference therebetween is greater than or equal to 5 GPa.
A fifth aspect a5 includes the laminated glass article of any one of a1 to a4, wherein the at least one glass cladding layer has a thickness TCLGreater than or equal to 35% of the total thickness T.
Sixth aspect a6 includes the laminated glass article of any one of a1 to a5, where the core refractive index n of the glass core layerCGreater than the cladding refractive index n of at least one glass cladding layerCL。
The seventh aspect a7 includes the laminated glass article of any one of a1 to a6, in which the clad refractive index nCLGreater than or equal to 1.45 and less than or equal to 1.55.
An eighth aspect A8 includes the laminated glass article of any one of a1 to a7, wherein the at least one glass cladding layer includes a first glass cladding layer and a second glass cladding layer, wherein: the first glass cladding layer is directly fused to the first surface of the glass core layer; and the second glass cladding layer is directly fused to a second surface of the glass core layer, the second surface being opposite the first surface of the glass core layer.
A ninth aspect a9 includes the laminated glass article of any one of a1 to A8, wherein: the glass core layer has a core coefficient of thermal expansion CTE from 20 ℃ to 300 DEG CC(ii) a At least one glass cladding layer has a cladding coefficient of thermal expansion CTE from 20 ℃ to 300 ℃CL(ii) a And CTECGreater than or equal to CTECL。
Tenth aspect a10 includes the laminated glass article of any one of a1 to a9, wherein the CTE is due in the laminated glass articleCAnd CTECLThe surface compressive stress caused by the difference between the above ranges is 10MPa or more and 100MPa or less.
An eleventh aspect a11 includes the laminated glass article of any one of a1 to a10, wherein the laminated glass article has an intrinsic CTECAnd CTECLA compression depth caused by the difference between, the compression depth being greater than or equal to 20% of the total thickness T.
A twelfth aspect a12 includes the laminated glass article of any one of a1 to a11, wherein the glass core layer is formed from an ion-exchangeable core glass composition.
A thirteenth aspect a13 includes the laminated glass article of any one of a1 to a12, wherein: the glass core layer is exposed at an edge of the laminated glass article; and the glass core layer comprises a surface compressive stress and a depth of compression at the edge of the laminated glass article.
A fourteenth aspect a14 includes the laminated glass article of any one of a1 through a13, wherein the laminated glass article is ion exchange strengthened such that the laminated glass article includes a compressive stress region due to ion exchange that extends from a surface of the at least one glass cladding layer and into a total thickness T of the laminated glass article to a depth of compression DOC.
A fifteenth aspect a15 includes the laminated glass article of any one of a1 to a14, wherein: the laminated glass article has a surface pressure due to ion exchange at a surface of at least one glass cladding layerCompressive stress CS0(ii) a And a depth of compression DOC due to ion exchange less than or equal to 30% of the thickness T of the at least one glass cladding layerCL。
A sixteenth aspect a16 includes the laminated glass article of any one of a1 to a15, wherein: the glass core layer has a core coefficient of thermal expansion CTE from 20 ℃ to 300 DEG CC(ii) a At least one glass cladding layer has a cladding coefficient of thermal expansion CTE from 20 ℃ to 300 ℃CL(ii) a And CTECGreater than or equal to CTECL。
A seventeenth aspect a17 includes the laminated glass article of any one of a1 to a16, wherein Na in the at least one glass cladding layer2The concentration of O decreases from the surface of the at least one glass cladding layer, is at a minimum at an intermediate point within the thickness of the at least one glass cladding layer, and increases from the intermediate point toward an interfacial layer located between the at least one glass cladding layer and the glass core layer.
An eighteenth aspect a18 includes the laminated glass article of any of a 1-a 17, wherein the weight gain due to ion exchange strengthening is less than 0.5%.
A nineteenth aspect a19 includes the laminated glass article of any one of a1 to a18, wherein the laminated glass article has a Knoop scratch initiation threshold (Knoop scratch initiation threshold) of greater than or equal to 2N and less than or equal to 8N.
A twentieth aspect a20 includes the laminated glass article of any one of a1 to a19, comprising a surface dynamic strength of greater than or equal to 400N.
A twentieth aspect a21 includes the laminated glass article of any one of a1 to a20, including an edge dynamic strength greater than or equal to 200N.
A twenty-second aspect a22 includes a laminated glass article comprising: a glass core layer formed from an ion-exchangeable core glass composition and comprising a core refractive index nCAnd a core coefficient of thermal expansion CTE from 20 ℃ to 300 ℃C(ii) a And at least one glass cladding layer directly fused to the glass core layer, the at least one glass cladding layer being formed from an ion-exchangeable cladding glass composition different from the ion-exchangeable core glass composition, the at least one glass cladding layerComprising a cladding refractive index nCLAnd a coating coefficient of thermal expansion CTE from 20 ℃ to 300 ℃CLWherein: the laminated glass article has a total thickness T and the at least one glass cladding layer has a thickness TCLThickness TCLGreater than or equal to 30% of the total thickness T; core refractive index n of glass core layerCGreater than the cladding refractive index n of at least one glass cladding layerCL(ii) a And CTECGreater than or equal to CTECL。
A twenty-third aspect A23 includes the laminated glass article of A22, where the cladding refractive index nCLGreater than or equal to 1.45 and less than or equal to 1.55.
A twenty-fourth aspect a24 includes the laminated glass article of any one of a22 to a23, wherein the CTE is due in the laminated glass articleCAnd CTECLThe surface compressive stress caused by the difference between the above ranges is 10MPa or more and 100MPa or less.
A twenty-fifth aspect a25 includes the laminated glass article of any one of a22 to a24, wherein the laminated glass article has an intrinsic CTECAnd CTECLA compression depth caused by the difference between, the compression depth being greater than or equal to 20% of the total thickness T.
A twenty-sixth aspect a26 includes the laminated glass article of any one of a22 to a25, wherein the laminated glass article has a knoop scratch initiation threshold greater than or equal to 2N and less than or equal to 8N.
A twenty-seventh aspect a27 includes the laminated glass article of any one of a22 to a26, wherein: the laminated glass article is ion-exchange strengthened and has a surface compressive stress CS at the surface of at least one glass cladding layer due to ion exchange0Is greater than or equal to 200 MPa; and a depth of compression DOC due to ion exchange is less than or equal to 20% of the thickness T of the at least one glass cladding layerCL。
A twenty-eighth aspect a28 includes the laminated glass article of any one of a22 to a27, including a surface dynamic strength of greater than or equal to 400N.
A twenty-ninth aspect a29 includes the laminated glass article of any one of a22 to a28, including an edge dynamic strength of greater than or equal to 200N.
It is to be understood that both the foregoing general description and the following detailed description describe various embodiments, and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments described herein and, together with the description, serve to explain the principles and operations of the claimed subject matter.
Drawings
Fig. 1 schematically depicts a cross-section of a laminated glass article according to one or more embodiments shown and described herein;
fig. 2 schematically depicts an interface region of a laminated glass article according to one or more embodiments shown and described herein;
fig. 3 schematically depicts an apparatus for forming a laminated glass article according to one or more embodiments shown and described herein;
FIG. 4 graphically depicts the weight gain (Y-coordinate) of a laminated glass article ion exchanged at different times as a function of the square root of the ion exchange time (X-coordinate);
FIG. 5 graphically depicts the alkali metal oxide concentration (Y-coordinate) in the laminated glass article as a function of depth (X-coordinate) for an ion-exchanged sample of the laminated glass article;
FIG. 6 graphically depicts the surface dynamic strength (Y-coordinate) of a sample and a control sample of a laminated glass article as a function of piston velocity (X-coordinate);
FIG. 7 graphically depicts the average surface dynamic strength (Y-coordinate) of a sample of laminated glass article and a control sample;
FIG. 8 graphically depicts edge dynamic strength (Y-coordinate) as a function of piston velocity (X-coordinate) for a sample and a control sample of a laminated glass article; and
fig. 9 graphically depicts the average edge dynamic strength (Y-coordinate) of the sample and the control sample of the laminated glass article.
Detailed Description
Reference will now be made in detail to embodiments of the laminated glass article, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Fig. 1 schematically depicts a cross-section of one embodiment of a laminated glass article, and is generally referred to by the reference numeral 100 in its entirety. The laminated glass article generally comprises: a glass core layer formed from a core glass composition and comprising a core glass elastic modulus EC(ii) a And at least one glass cladding layer directly fused to the glass core layer. At least one glass cladding layer may be formed from an ion-exchangeable cladding glass composition different from the core glass composition and including a cladding glass elastic modulus ECL. The laminated glass article can have a total thickness T, and the at least one glass cladding layer can have a thickness TCLThickness TCLGreater than or equal to 30% of the total thickness T. ECComparable ECLAt least 5% greater. Various embodiments of laminated glass articles and methods of forming the same will be described in more detail herein with particular reference to the claims.
Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
Directional terms as used herein, such as upper, lower, right, left, front, rear, top, bottom, are made with reference to the drawings as shown only, and are not intended to imply absolute orientations.
Unless otherwise expressly stated, any method set forth herein is not to be construed as requiring that its steps be performed in a particular order, nor in any case in any apparatus requiring a particular orientation. Thus, if a method claim does not actually recite an order to be followed by its steps, or any apparatus claim does not actually recite an order or orientation of individual components, or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, or that a specific order or orientation of components of an apparatus is not recited, it is no way intended that an order or orientation be inferred, in any respect. This is true for any possible non-explicit basis for explanation, including: logical considerations for the arrangement of steps, operational flows, component orders, or component orientations; derived from the general meaning of grammatical organization or punctuation; and the number or type of embodiments described in the specification.
As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a component" thus includes aspects having two or more such components, unless the context clearly dictates otherwise.
The term "CTE" as used herein refers to the coefficient of thermal expansion of the glass composition averaged over a temperature range from about 20 ℃ to about 300 ℃.
The elastic modulus (also referred to as young's modulus) of the different layers of the glass laminate is provided in gigapascals (GPa). The modulus of elasticity of the glass was determined by resonance ultrasonic spectroscopy for a bulk sample of each glass composition.
The term "softening point" as used herein means that the viscosity of the glass composition is 1 × 107.6The temperature of poise.
The term "annealing point" as used herein means that the viscosity of the glass composition is 1 × 1013The temperature of poise.
The terms "strain point" and "Tstrain" as used herein refer to glass compositions having a viscosity of 3X 1014The temperature of poise.
Compressive stresses, including surface compressive stresses, can be measured with a surface stress meter (FSM), which can be a commercially available instrument such as FSM-6000 manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurements rely on the accurate measurement of Stress Optical Constants (SOC) related to the birefringence of the glass. SOC was measured according to procedure C (Glass Disc Method) entitled "Standard Test Method for measuring the Glass Stress-Optical Coefficient" described in ASTM Standard C770-16, the contents of which are incorporated herein by reference in their entirety. Depth of compression (DOC) is also measured using FSM. The maximum Central Tension (CT) value is measured using the scattered light polarizer (SCALP) technique known in the art.
The concentration distribution of various constituent components (e.g., alkali constituent components) in the glass is measured by Electron Probe Microanalysis (EPMA). For example, EPMA can be used to distinguish between compressive stress in the glass due to ion exchange of alkali ions into the glass and compressive stress due to lamination.
The phrases "depth of compression" and "DOC" refer to the location in the glass where compressive stress is converted to tensile stress.
Embodiments described herein provide laminated glass articles having high scratch resistance while exhibiting improved resistance to drop-induced cracking. In particular, embodiments described herein include laminated glass articles including a glass cladding layer and a glass core layer having different characteristics to facilitate different properties in the glass. In particular, glass cladding has a high resistance to scratching and crack formation when subjected to sharp contacts. Further, the glasses used for the glass cladding layer and the glass core layer are selected so that compressive stress can be developed to a deep depth of compression upon cooling of the glass after molding. In embodiments, at least the glass cladding layer is also adapted to be strengthened by ion exchange, which may further improve the resistance of the laminated glass article to drop-induced damage. In some embodiments, the glass core layer may also be adapted to be strengthened by ion exchange, which helps to strengthen the portions of the glass core layer that are exposed at least at the edges of the laminated glass article after separation of the laminated glass article from the sheet or ribbon.
Referring now to fig. 1, a cross-section of a laminated glass article 100 is schematically depicted. The laminated glass article 100 generally includes a glass core layer 102 and at least one glass cladding layer 104 a. In the embodiment of the laminated glass article 100 shown in fig. 1, the laminated glass article includes a first glass cladding layer 104a and a second glass cladding layer 104b, the first glass cladding layer 104a and the second glass cladding layer 104b being located on opposite sides of the glass core layer 102. Although fig. 1 schematically depicts the laminated glass article 100 as a laminated glass sheet, it is understood that other configurations and form factors are contemplated and are possible. For example, the laminated glass article can have a non-planar configuration, such as a curved glass sheet or the like. Alternatively, the laminated glass article can be a laminated glass tube, container, or the like.
In the embodiments of the laminated glass article 100 described herein, the glass core layer 102 generally includes a first major surface 103a and a second major surface 103b, the second major surface 103b being opposite the first major surface 103 a. A first glass cladding layer 104a is fused to the first major surface 103a of the glass core layer 102 and a second glass cladding layer 104b is fused to the second major surface 103b of the glass core layer 102.
In the embodiments described herein, the glass cladding layers 104a, 104b are fused to the glass core layer 102 without any other non-glass materials, such as adhesives, coatings, etc., disposed between the glass core layer 102 and the glass cladding layers 104a, 104 b. Thus, in some embodiments, the glass cladding layers 104a, 104b are fused directly to the glass core layer 102 or are directly adjacent to the glass core layer 102.
Referring now to fig. 2, an enlarged view of the interface between the glass core layer 102 and the glass cladding layers 104a, 104b is schematically depicted. In an embodiment, the laminated glass article 100 includes interface regions 106a, 106b at the interface between the glass core layer 102 and the glass cladding layers 104a, 104 b. The interface regions 106a, 106b are formed when the glass core layer 102 and the glass cladding layers 104a, 104b are fused together. The interface regions 106a, 106b are thin layers comprised of a mixture of cladding compositions forming the glass cladding layers 104a, 104b and core compositions forming the glass core layer 102. For example, the interface regions 106a, 106b may include an intermediate glass layer and/or a diffusion layer formed at the interface of the glass core layer and the glass cladding layer (e.g., by diffusing one or more components of the glass core layer and the glass cladding layer into the diffusion layer). In some embodiments, the laminated glass article 100 comprises a glass-to-glass laminate (e.g., an in-situ fused multiple layer glass-to-glass laminate), wherein the interface between directly adjacent glass layers is a glass-to-glass interface.
Referring again to fig. 1, in the embodiments described herein, the total thickness T of the laminated glass article 100 is the sum of the thickness of the glass core layer 102 and the thickness of each of the glass cladding layers 104a, 104b along the Z-direction of the coordinate axis depicted in fig. 1. In embodiments, the total thickness T of the laminated glass article can be greater than or equal to 0.5mm and less than or equal to 300 mm. In some embodiments, the total thickness T of the laminated glass article can be greater than or equal to 0.8mm and less than or equal to 1.5. In some embodiments, the total thickness T of the laminated glass article can be greater than or equal to 0.9mm and less than or equal to 1.0 mm.
In an embodiment, the thickness of each glass cladding layer 104a, 104b is greater than or equal to 30% of the total thickness T of the laminated glass article. In embodiments, the thickness of each glass cladding layer 104a, 104b can be greater than or equal to 32% of the total thickness T of the laminated glass article, or even greater than or equal to 33% of the total thickness T of the laminated glass article. In embodiments, the thickness of each glass cladding layer 104a, 104b can be greater than or equal to 34% of the total thickness T of the laminated glass article, or even greater than or equal to 35% of the total thickness T of the laminated glass article. A total thickness T of the laminated glass article having a glass cladding layer thickness of greater than or equal to 30% may help prevent catastrophic damage to the glass article due to the introduction of deep defects (e.g., scratches, etc.) in the surface of the laminated glass article. In the embodiments described herein, the composition of the glass cladding layers 104a, 104b is different than the composition of the glass core layer 102 in order to achieve specific properties in the final laminated glass article.
For example, the glass core layer 102 and the glass cladding layers 104a, 104b may have different free volumes, resulting in different properties for the glass core layer 102 and the glass cladding layers 104a, 104 b. The phrase "free volume" as used herein refers to the space in a glass structure not occupied by atoms or structural units. In particular, the glass cladding layers 104a, 104b may have a relatively high free volume compared to the glass core layer 102. The relatively high free volume in the glass cladding layers 104a, 104b results in densification (i.e., scratching) of the glass during a sharp impact event and less shear forces, which in turn results in less glass subsurface damage and less residual stress in the glass. However, a relatively high free volume in the glass does not necessarily improve the resistance to drop-induced damage. For example, glasses with relatively high free volume typically have lower surface compression after ion exchange strengthening compared to glasses with relatively low free volume.
Thus, in the embodiments described herein, the glass core layer 102 has a lower free volume than the glass cladding layers 104a, 104 b. When the glass core layer 102 is strengthened by ion exchange, the relatively low free volume of the glass core layer 102 helps to achieve a higher compressive stress in the glass core layer 102. The compressive stress in the glass core layer 102 (e.g., at the edges of the glass core layer) improves the resistance of the laminated glass article 100 to drop-induced damage.
Based on the foregoing, a laminated glass article 100 having improved scratch resistance and improved resistance to drop-induced damage can be obtained by using a glass having a relatively higher free volume for the glass cladding layers 104a, 104b and a glass having a relatively lower free volume for the glass core layer 102.
The free volume of glass is related to the elastic modulus of the glass. In particular, it is generally understood that the elastic modulus of glass decreases with increasing free volume and increases with decreasing free volume. Thus, in the embodiments described herein, the elastic modulus E of the glass core layer 102CGreater than the modulus of elasticity E of the glass cladding layers 104a, 104bCL. In some embodiments, the elastic modulus E of the glass core layer 102CElastic modulus E of the glass cladding layers 104a and 104bCLAt least 5% greater. For example, in some embodiments, the elastic modulus E of the glass core layer 102CElastic modulus E of the glass cladding layers 104a and 104bCLAt least 10% larger, or even more than glass-cladModulus of elasticity E of the layers 104a, 104bCLAt least 15% greater. In other embodiments, the elastic modulus E of the glass core layer 102CElastic modulus E of the glass cladding layers 104a and 104bCLAt least 20% greater, or even greater than the modulus of elasticity E of the glass cladding layers 104a, 104bCLAt least 25% greater.
In some embodiments, the elastic modulus E of the glass core layer 102CAnd the elastic modulus E of the glass cladding layers 104a and 104bCLThe difference between is greater than or equal to 5GPa, or even greater than or equal to 10 GPa. For example, in some of these embodiments, the elastic modulus E of the glass core layer 102CAnd the elastic modulus E of the glass cladding layers 104a and 104bCLThe difference between is greater than or equal to 15GPa, or even greater than or equal to 20 GPa. In other embodiments, the elastic modulus E of the glass core layer 102CAnd the elastic modulus E of the glass cladding layers 104a and 104bCLThe difference therebetween is greater than or equal to 25GPa, or even greater than or equal to 30 GPa.
In some embodiments, the glass cladding layers 104a, 104b have an elastic modulus ECLIs less than or equal to 76.5GPa, and the glass core layer 102 has an elastic modulus ECIs greater than 76.5 GPa. For example, in some embodiments, the glass cladding layers 104a, 104b have an elastic modulus ECLIs less than or equal to 76.5GPa and greater than or equal to 60GPa, and the elastic modulus E of the glass core layer 102CIs greater than 76.5GPa and less than or equal to 90 GPa. In some embodiments, the glass cladding layers 104a, 104b have an elastic modulus ECLIs 71.5GPa or less, and the elastic modulus E of the glass core layer 102CIs greater than 76.5 GPa.
Similar to the modulus of elasticity, the free volume of a glass is also related to the refractive index n of the glass. In the embodiments described herein, the core refractive index n of the glass core layer 102CCladding refractive index n greater than glass cladding layers 104a, 104bCL. For example, in an embodiment, the cladding refractive index nCLIs greater than or equal to 1.45 and less than or equal to 1.55, or even greater than or equal to 1.48 and less than or equal to 1.505. In these embodiments, the core refractive index nCIs greater than or equal to 1.50 and less than or equal to 1.60,or even greater than or equal to 1.506 and less than or equal to 1.55.
Still referring to fig. 1, in the embodiments described herein, the laminated glass article 100 is formed such that there is a mismatch between the Coefficients of Thermal Expansion (CTE) of the glass core layer 102 and the glass cladding layers 104a, 104 b. The CTE mismatch of the glass core layer 102 and the glass cladding layers 104a, 104b results in the formation of compressive stresses extending from the surfaces 108a, 108b of the laminated glass article 100 into the thickness of the laminated glass article. For example, in some embodiments described herein, the glass cladding layers 104a, 104b are formed from a material having an average cladding coefficient of thermal expansion CTECLAnd the glass core layer 102 is formed from a glass composition having an average core coefficient of thermal expansion CTECAre formed from different glass compositions. CTE (coefficient of thermal expansion)CGreater than CTECL(i.e., CTE)C>CTECL) This causes the glass cladding layers 104a, 104b to be compressively stressed. The resulting compressive stress enhances the ability of the laminated glass article to withstand the introduction of surface flaws without catastrophic degradation.
Due to the CTE difference between the core and cladding layers, the compressive stress in the cladding layer can be approximated by the following equation:
wherein t iscoreIs the core thickness, tcladTo cover thickness, αcladTo cover the coefficient of thermal expansion, alphacoreIs the core coefficient of thermal expansion, Δ T isEffective temperature difference (effective temperature difference), EcoreIs the modulus of elasticity of the core, EcladIs the modulus of elasticity, v, of the coatingcoreIs the Poisson's ratio of the core, and vcladIs the poisson's ratio of the coating. In general, αclad<<Δ T and αcoreΔT<<1, therefore:
for example, in some embodiments, the composition is formulated to have a particle size of less than or equal to about 72x10-7Average coating CTE per degree CCLThe glass composition (which is averaged over a range of 20 ℃ to 300 ℃) forms a glass cladding layer. In some embodiments, the average clad CTE of the clad glass composition averaged over the range of 20 ℃ to 300 ℃CLMay be less than or equal to about 70x10-7V. C. In other embodiments, the average clad CTE of the clad glass composition averaged over the range of 20 ℃ to 300 ℃CLMay be less than or equal to about 65x10-7V. C. In other embodiments, the average clad CTE of the clad glass composition averaged over the range of 20 ℃ to 300 ℃CLMay be less than or equal to about 60x10-7Per deg.C, or even less than or equal to about 55x10-7/℃。
However, the glass composition forming the glass core layer may have an average coefficient of thermal expansion greater than 72x10 in the range of 20 ℃ to 300 ℃-7V. C. In some of these embodiments, the core glass composition of the glass core layer has an average core CTE in a range from 20 ℃ to 300 ℃CCan be greater than or equal to about 75x10-7V. C. In other embodiments, the glass composition of the glass core layer has an average core CTE that averages over a range from 20 ℃ to 300 ℃CCan be greater than or equal to about 80x10-7V. C. In other embodiments, the glass composition of the glass core layer has an average core CTE that averages over a range from 20 ℃ to 300 ℃CCan be greater than or equal to about 90x10-7/℃。
In the embodiments described herein, the glass coreThe difference in CTE between the layer 102 and the glass cladding layers 104a, 104b (i.e., | CTE)C–CTECL|) is sufficient to generate surface compressive stress in the cladding layer. In some embodiments, the CTE difference between the glass core layer 102 and the glass cladding layers 104a, 104b is sufficient to produce a surface compressive stress in the glass cladding layers 104a, 104b of greater than or equal to 10MPa and less than or equal to 100MPa extending from the surface of the glass cladding layers 104a, 104b and through the thickness of the glass cladding layers 104a, 104 b. That is, the compressive stress due to the CTE difference between the glass core layer 102 and the glass cladding layers 104a, 104b is 10MPa or more and 100MPa or less. In these embodiments, the compressive stress due to the CTE difference between the glass core layer 102 and the glass cladding layers 104a, 104b extends to a depth of compression (DOC) that is greater than or equal to 20% of the total thickness T of the laminated glass article 100. For example, in some embodiments, the compressive stress due to the CTE difference between the glass core layer 102 and the glass cladding layers 104a, 104b extends to a depth of compression that is greater than or equal to 22% of the total thickness T of the laminated glass article 100. In some embodiments, the compressive stress due to the CTE difference between the glass core layer 102 and the glass cladding layers 104a, 104b extends to a depth of compression that is greater than or equal to 25% of the total thickness T of the laminated glass article 100.
In some embodiments, the CTE difference between the glass core layer and the glass cladding layer is greater than or equal to about 5x10-7/° c or even 10x10-7V. C. In some other embodiments, the CTE difference between the glass core layer and the glass cladding layer is greater than or equal to about 20x10-7/° c or even 30x10-7V. C. In other embodiments, the CTE difference between the glass core layer and the glass cladding layer is greater than or equal to about 40x10-7/° c or even 50x10-7/℃。
In the embodiments described herein, the glass cladding layers 104a, 104b may be formed from ion-exchangeable cladding glass compositions. In some of these embodiments, the glass core layer 102 is formed from an ion-exchangeable core glass composition and the glass cladding layers 104a, 104b are formed from ion-exchangeable cladding glass compositions. In thatIn these embodiments, both the ion-exchangeable core glass composition and the ion-exchangeable clad glass composition may include Li2O and Na2O to facilitate ion exchange strengthening of the respective layers. When the glass cladding layers 104a, 104b are ion-exchange strengthened, the resistance of the laminated glass article 100 to damage caused by defects introduced into the surface of the laminated glass article can be further improved. Similarly, when ion exchange strengthening is performed on the glass core layer 102 (particularly ion exchange strengthening of the glass core layer 102 exposed at the edges of the laminated glass article 100 after separation of the laminated glass article 100 from the sheets or ribbons of laminated glass), the exposure tension at the edges can be eliminated and thereby improve the resistance of the laminated glass article 100 to damage at the edges.
Thus, it should be understood that in some embodiments, the laminated glass article 100 may also be strengthened by ion exchange to further enhance the properties of the laminated glass article 100. The combination of the CTE difference between the glass core layer 102 and the glass cladding layers 104a, 104b and the ion exchange strengthening results in a unique stress profile. In particular, the stress profile in the ion exchanged laminated glass article 100 is the sum of the stress profile due to the CTE difference between the glass cladding layer and the glass core layer and the stress profile due to the ion exchange. In embodiments, the compressive stress in the region from the glass surface to a certain depth from the surface (about 20% or even 30% of the thickness of the glass cladding layer) includes both compressive stress due to CTE differences between the glass core layer and the glass cladding layer and compressive stress due to ion exchange strengthening. That is, the compressive stress due to ion exchange extends to a depth of compression that is 20% or even 30% of the thickness of each glass cladding layer 104a, 104 b.
More particularly, in some embodiments, the glass cladding layers 104a, 104b and optionally the glass core layer 102 may be formed from glass compositions that may be ion exchange strengthened. The presence of alkali metal oxides in the glass core layer 102 and the glass cladding layers 104a, 104b helps strengthen the glass by ion exchange. In particular, alkali metal ions (e.g., potassium ions, sodium ions, lithium ions, etc.) move sufficiently in the glass to be usefulPromoting ion exchange. Strengthening of the laminated glass article by ion exchange can be achieved by: at a temperature of from 350 ℃ to 500 ℃, in molten KNO3Molten NaNO3Or a combination thereof, for less than about 30 hours or even less than about 20 hours.
In embodiments where the laminated glass article 100 is strengthened by ion exchange, the laminated glass article has a surface compressive stress CS due to ion exchange0And a compressive stress region resulting from ion exchange extending from the surfaces 108a, 108b of the laminated glass article 100 and into the total thickness T to a depth of compression DOC. In some of these embodiments, the surface compressive stress due to ion exchange is greater than or equal to 200MPa or even greater than or equal to 500 MPa. In some of these embodiments, the surface compressive stress due to ion exchange is greater than or equal to 600MPa or even greater than or equal to 700 MPa.
In some embodiments, the depth of compression due to ion exchange is less than or equal to 30% of the thickness of the glass cladding layer, and compressive stress is formed in the glass cladding layer due to ion exchange. In some embodiments, the depth of compression due to ion exchange is less than or equal to 20% of the thickness of the glass cladding layer, and compressive stress is formed in the glass cladding layer due to ion exchange. In some embodiments, the depth of compression due to ion exchange is less than or equal to 15% of the thickness of the glass cladding layer, and compressive stress is formed in the glass cladding layer due to ion exchange. In some embodiments, the depth of compression due to ion exchange is less than or equal to 10% of the thickness of the glass cladding layer, and compressive stress is formed in the glass cladding layer due to ion exchange.
As described above, in embodiments where the laminated glass article is separated from the continuous glass ribbon, the separation may expose the glass core layer and a central tension in the glass core layer along at least one edge of the laminated glass article. In embodiments where the laminated glass article includes a glass core layer formed of ion-exchangeable glass, the exposed edges and the exposed central tension of the laminated glass article may be ion-exchange strengthened to create a compressive stress in the surface of the exposed glass core layer that extends to a depth of compression. The surface compressive stress in the exposed glass core layer eliminates center tension at the exposed edges and reduces the risk of damage to the laminated glass article from the exposed edges. In these embodiments, the laminated glass article may have a surface compressive stress along the entire exposed edge (i.e., in the glass cladding layer and the glass core layer).
In embodiments where compressive stress is introduced into the laminated glass article through both lamination and ion exchange, the combination of lamination and ion exchange shortens the ion exchange time required to reach a particular depth of compression and/or surface compressive stress at a given ion exchange temperature. More particularly, forming a laminated glass article from a glass core layer having a CTE difference between the glass core layer and the glass cladding layers and one or more glass cladding layers results in surface compressive stresses of the glass article extending into the overall thickness of the glass article to a depth of compression. Because the laminated glass article has an existing surface compressive stress and depth of compression prior to ion exchange strengthening, the time required to reach a particular surface compressive stress or depth of compression through ion exchange can be reduced.
The reduced ion exchange time due to the existing surface compressive stress minimizes the weight gain of the glass substrate due to ion exchange. In particular, ion exchange strengthening is achieved by exchanging smaller (and lighter) ions in the glass network with larger (and heavier) ions from a molten salt bath. However, because the glass cladding layer has an existing surface compressive stress, fewer ion exchange events (i.e., exchanging smaller ions in the glass for larger ions from the molten salt bath) are required to achieve the desired increase in surface compressive stress. Thus, a laminated glass article having an existing surface compressive stress due to lamination has less weight gain during ion exchange to reach the same surface compressive stress as compared to the same laminated glass article (or a glass article formed only from the clad glass composition and having no existing surface compressive stress profile) having no existing surface compressive stress profile.
In the embodiments described herein, the laminated glass article has a weight gain due to ion exchange strengthening of less than 0.5%. In some embodiments, the laminated glass article has a weight gain due to ion exchange strengthening of less than 0.4%. In some embodiments, the laminated glass article has a weight gain due to ion exchange strengthening of less than 0.3%. In some embodiments, the laminated glass article has a weight gain due to ion exchange strengthening of less than 0.2%.
Referring again to FIG. 2, prior to ion exchange strengthening, the glass network of the glass cladding layers 104a, 104b has various compositional components (e.g., SiO)2And B2O3Glass former, Al2O3Etc. intermediate and CaO, Na2O, etc.) is substantially uniformly distributed from the surfaces 108a, 108b of the laminated glass article 100 to the respective interface regions 106a, 106 b. For example, the glass cladding layers 104a, 104b include at least one glass former, and the concentration of the glass former is substantially constant from the surfaces 108a, 108b of the laminated glass article 100 to the cladding side of the interface regions 106a, 106 b. In addition, the glass cladding layers 104a, 104b include at least one modifier (e.g., Na)2O and/or another alkali metal oxide) and the concentration of the modifying agent is substantially constant from the surfaces 108a, 108b of the laminated glass article 100 to the clad side of the interface regions 106a, 106 b.
However, after ion exchange, at least the alkali metal oxide (e.g., K) in the glass cladding layers 104a, 104b2O and/or Na2O) varies with depth from the surfaces 108a, 108b of the laminated glass article 100. For example, in a laminated glass article comprising Na2O and in a molten salt bath comprising sodium ions (e.g., comprising NaNO)3In the molten salt bath) of (b), Na2The concentration of O is from the surfaces 108a, 108b of the laminated glass article 100 to an intermediate point P of the thickness of the glass cladding layers 104a, 104bIFalls and at an intermediate point PIIs at a minimum and is from the intermediate point PIRising toward the cladding side of the interface regions 106a, 106 b. That is, the glass cladding layer 104a. 104b of Na2The concentration of O varies as a function of distance from the surfaces 108a, 108 b.
Although the concentration of alkali metal oxide in the glass cladding layer may vary due to ion exchange strengthening, it is understood that the other components in the glass network (i.e., the glass former, the intermediate, and the non-mobile modifier, such as alkaline earth metal oxides (CaO, MgO, etc.)) remain substantially the same (i.e., substantially uniform throughout the thickness of the glass cladding layer, and substantially uniform throughout the thickness of the glass core layer).
In some embodiments, the glass core layer may be formed from one of the ion-exchangeable core glass compositions listed in table 1A and table 1B below. However, it is understood that other compositions of the glass core layer 102 are contemplated and possible.
Table 1A: example glass core layer compositions
Table 1B: example glass core layer compositions
Composition analyzed (mol%)
C8
C9
C10
C11
C12
C13
SiO2
60.32
59.80
60.49
59.77
60.35
59.79
Al2O3
16.40
16.34
16.28
16.34
16.36
16.32
B2O3
1.47
1.46
0.98
0.97
0.49
0.49
P2O5
0.99
1.49
0.98
1.49
0.99
1.48
Li2O
8.29
8.43
8.31
8.41
8.31
8.34
Na2O
8.94
8.91
8.94
8.91
8.95
8.97
MgO
3.53
3.53
3.97
4.06
4.50
4.56
SnO2
0.06
0.05
0.05
0.05
0.06
0.05
Density (g/cm)3)
2.438
2.436
2.444
2.443
2.45
2.449
FE strain point (. degree. C.)
546
557
551
565
563
573
FE annealing Point (. degree. C.)
591
604
597
611
609
619
FE softening point (. degree. C.)
861
859
864
858
851
864
CTE*10-7(1/℃)
78.6
79.2
78.6
79.8
78.4
79
Stress optical coefficient (nm/mm/MPa)
2.891
2.919
2.866
2.874
2.833
2.861
Refractive index
1.5149
1.5149
1.5164
1.5148
1.5169
1.5157
Modulus of elasticity (GPa)
80.53
80.32
81.56
81.01
82.46
82.05
Poisson ratio
0.218
0.224
0.225
0.226
0.226
0.224
In some embodiments, the glass cladding layer may be formed from one or more ion-exchangeable cladding glass compositions listed in table 2A and table 2B below. However, it is understood that other compositions of glass cladding layers 104a, 104b are contemplated and possible.
Table 2A: example coated glass compositions
Table 2B: example coated glass compositions
The laminated glass articles described herein can be manufactured using a variety of processes including, but not limited to, a lamination slot draw process, a lamination float process, or a fusion lamination process. Each of these lamination processes generally involves flowing a first molten glass composition, flowing a second molten glass composition, and contacting the first molten glass composition with the second molten glass composition at a temperature greater than the glass transition temperature of either glass composition to form an interface between the two compositions such that the first molten glass composition and the second molten glass composition fuse together at the interface as the glass cools and solidifies.
In one particular embodiment, the laminated glass article 100 described herein may be formed by a melt lamination process (such as the process described in U.S. patent No. 4,214,886, which is incorporated herein by reference). For example, referring to FIG. 3, a laminate fusion draw apparatus 200 for forming a laminated glass article includes an upper overflow distributor or isopipe (isopipe)202 positioned above a lower overflow distributor or isopipe 204. The overflow distributor 202 includes a trough 210, and the molten glass cladding composition 206 is fed into the trough 210 from a melter (not shown). Similarly, lower overflow distributor 204 includes trough 212, and molten glass core composition 208 is fed from a melter (not shown) into trough 212.
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 underflow distributor 204. The outer forming surfaces 216, 218 of lower overflow distributor 204 meet at root 220. Thus, the molten glass core composition 208 flowing over the outer forming surfaces 216, 218 rejoins at the root 220 of the underflow distributor 204 to form the glass core layer 102 of the laminated glass article.
At the same time, the molten glass cladding composition 206 overflows the trough 210 formed in the overflow distributor 202 and flows over the outer forming surfaces 222, 224 of the overflow distributor 202. The molten glass cladding composition 206 is deflected outward 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, fuses to the molten glass core composition, and forms glass cladding layers 104a, 104b around the glass core layer 102.
Although fig. 3 schematically depicts a particular apparatus for forming a planar laminated glass article, such as a sheet or a ribbon, it should be understood that other geometric configurations are possible. For example, cylindrical laminated glass articles can be formed using apparatus and methods such as those described in U.S. patent No. 4,023,953.
In the embodiments described herein, the molten glass core composition 208 generally has an average core coefficient of thermal expansion CTE, as described aboveCGreater than the average cladding coefficient of thermal expansion CTE of the molten glass cladding composition 206CL. Thus, as the glass core layer 102 and the glass cladding layers 104a, 104b cool, the difference in the coefficients of thermal expansion of the glass core layer 102 and the glass cladding layers 104a, 104b results in compressive stress in the glass cladding layers 104a, 104 b. The compressive stress increases the strength of the resulting laminated glass article.
Knoop Scratch Thresholds (KST) as described herein were determined using a Knoop diamond indenter. The scratch threshold is determined by first determining the load range at which the transverse crack starts. Once the load range is determined, a series of 5mm long scratches are made at increasing constant loads using a speed of 4mm/s to identify the Knoop scratch threshold, with three or more scratches per load. Transverse cracks are defined as persistent cracks greater than twice the width of the groove.
In the embodiments described herein, the glass laminate has a knoop scratch threshold greater than or equal to 2 newtons (N). In some embodiments, the glass laminate has a knoop scratch threshold greater than or equal to 4N, or even greater than or equal to 6N. In embodiments, the glass laminates described herein have a knoop scratch threshold greater than or equal to 2N and less than or equal to 8N, or even greater than or equal to 4N and less than or equal to 8N. In some of these embodiments, the glass laminates described herein have a knoop scratch threshold greater than or equal to 2N and less than or equal to 4N, or even greater than or equal to 4N and less than or equal to 6N. In other embodiments, the glass laminates described herein have a knoop scratch threshold greater than or equal to 6N and less than or equal to 8N.
In the embodiments described herein, the damage resistance of the laminated glass article under dynamic loading conditions can be determined by a surface dynamic impact test. The surface dynamic impact test involves impacting a disc-like 30 grit SiC sandpaper at a predetermined speed against the surface of the laminated glass article. During impact, the laminated glass article (i.e., sample) was fixed in a jig, and the impact force was measured with a piezoelectric load cell (piezo electric load cell) attached to the laminated glass article. The impact force that causes damage to the laminated glass article is considered to be the surface dynamic strength of the laminated glass article.
Specifically, 1-inch disk 30-grit SiC paper was secured to the end of the piston, which was secured in a frictionless air bearing. The piston and air bearing are included in a test carrier that is pushed by a variable speed belt slide. The glass sample was fixed to a piezoelectric load cell located at the end of the belt slide. The belt slide pushes the test carrier towards the sample, at the end of the belt slide the carrier decelerates rapidly, causing the piston to push forward through momentum. The piston, more specifically the sandpaper attached to the end of the piston, hit the glass surface in the center of the glass sample and bounce freely on the air bearing. The actual speed of the piston before impact is measured by a pair of shutters (photogates). The impact force is recorded by a piezoelectric sensor.
In the embodiments described herein, the surface dynamic strength of the laminated glass article is greater than or equal to 400 newtons (N). In some embodiments, the surface dynamic strength of the laminated glass article is greater than or equal to 500N, or even greater than or equal to 600N. In some embodiments, the surface dynamic strength of the laminated glass article is greater than or equal to 700N, or even greater than or equal to 800N. In some embodiments, the surface dynamic strength of the laminated glass article is greater than or equal to 900N, or even greater than or equal to 1000N. In some embodiments, the surface dynamic strength of the laminated glass article is greater than or equal to 1000N, or even greater than or equal to 1200N. In an embodiment, the surface dynamic strength of the laminated glass article is greater than or equal to 400N and less than or equal to 1200N. In an embodiment, the surface dynamic strength of the laminated glass article is greater than or equal to 500N and less than or equal to 1100N. In an embodiment, the surface dynamic strength of the laminated glass article is greater than or equal to 500N and less than or equal to 1000N. In an embodiment, the laminated glass article has a surface dynamic strength greater than or equal to 500N and less than or equal to 900N. In an embodiment, the surface dynamic strength of the laminated glass article is greater than or equal to 600N and less than or equal to 800N.
In the embodiments described herein, the resistance of the laminated glass article to failure of the article edge under dynamic loading conditions can be determined by edge dynamic impact testing. The edge dynamic impact test involves impacting a tungsten carbide (WC) rod body against the edge of the laminated glass article at a predetermined velocity. The long axis of the WC rod body is perpendicular to the surface of the laminated glass article upon impact. During impact, the laminated glass article (i.e., sample) was fixed in a jig, and the impact force was measured with a piezoelectric load cell (piezo electric load cell) attached to the laminated glass article. The impact force that causes damage to the laminated glass article is considered to be the edge dynamic strength of the laminated glass article.
Specifically, an 3/8 inch WC rod was secured to the end of the piston, which was secured in a frictionless air bearing. The piston and air bearing are included in a test carrier that is pushed by a variable speed belt slide. The glass sample was fixed to a piezoelectric load cell located at the end of the belt slide. The belt slide pushes the test carrier towards the sample, at the end of the belt slide the carrier decelerates rapidly, causing the piston to push forward through momentum. The piston, more specifically the WC rod fixed to the end of the piston, hit the edge of the glass sample and bounce freely on the air bearing. The actual speed of the piston before impact is measured by a pair of shutters (photogates). The impact force is recorded by a piezoelectric sensor.
In embodiments described herein, the edge dynamic strength of the laminated glass article prior to ion exchange is greater than or equal to 200 newtons (N). In some embodiments, the edge dynamic strength of the laminated glass article prior to ion exchange is greater than or equal to 300N, or even greater than or equal to 400N. In an embodiment, the edge dynamic strength of the laminated glass article prior to ion exchange is greater than or equal to 200N and less than or equal to 500N. In an embodiment, the edge dynamic strength of the laminated glass article prior to ion exchange is greater than or equal to 300N and less than or equal to 500N. In an embodiment, the edge dynamic strength of the laminated glass article prior to ion exchange is greater than or equal to 300N and less than or equal to 500N.
In embodiments described herein, the edge dynamic strength of the laminated glass article after ion exchange is greater than or equal to 500 newtons (N). In some embodiments, the edge dynamic strength of the laminated glass article after ion exchange is greater than or equal to 500N, or even greater than or equal to 600N. In some embodiments, the edge dynamic strength of the laminated glass article after ion exchange is greater than or equal to 700N, or even greater than or equal to 800N. In an embodiment, the laminated glass article has an edge dynamic strength after ion exchange of greater than or equal to 500N and less than or equal to 900N. In an embodiment, the laminated glass article has an edge dynamic strength after ion exchange of greater than or equal to 600N and less than or equal to 800N. In an embodiment, the laminated glass article has an edge dynamic strength after ion exchange of greater than or equal to 700N and less than or equal to 800N.
The laminated glass articles described herein can be used in a variety of applications, including, for example, automotive glass, architectural, appliance, and consumer electronics (e.g., cover glass) applications. The combination of a thin ion-exchangeable glass cladding layer having a relatively low modulus of elasticity and an ion-exchangeable glass core layer having a relatively high modulus of elasticity provides improved resistance to surface damage (e.g., scratch resistance) as well as improved resistance to sharp impact damage (e.g., drop-induced damage and breakage) to the laminated glass article.
Examples of the invention
The embodiments described herein will be further clarified by the following examples.
Example 1
A three layer laminated glass article was formed from core glass composition C1 (table 1) and clad glass composition CL1 (table 2A). The glass cladding layer has a thickness of from about 200 μm to about 250 μm. The thickness of the glass core layer is approximately 300 μm. The glass core layer had an elastic modulus of 76.67GPa and a CTE of 84x10-7V. C. The glass cladding layer has an elastic modulus of 67.78GPa and a CTE of 49.6x10-7V. C. The compressive stress in the glass cladding layer due to the CTE mismatch between the glass cladding layer and the glass core layer was determined to be about 66MPa based on the values of the elastic modulus, poisson's ratio, and CTE of each glass. For the purpose of this calculation, Δ T is estimated as the difference between the lower strain point temperature and room temperature.
By immersing a sample of the laminated glass article in 20 wt% NaNO at a temperature of 390 deg.C380% by weight of KNO3For 0.5 hours, 2 hours, 4 hours, 7.5 hours, or 16 hours, respectively, to ion exchange strengthen the sample of the laminated glass article. The samples were weighed before and after the ion exchange treatment to determine the weight change due to ion exchange. The samples were also qualitatively examined to determine if the ion exchange process resulted in any warping or other deformation in the glass. No warpage or deformation was observed for any of the samples.
After the ion exchange strengthening, the Compressive Stress (CS) and the depth of compression were measured with a Fundamental Stress Meter (FSM) instrument. The samples ion exchanged for 2 hours had a surface compressive stress of approximately 390MPa and a depth of compression of approximately 7 μm. The sample ion exchanged for 4 hours had a surface compressive stress of approximately 415MPa and a depth of compression of approximately 10 μm. The sample ion exchanged for 7.5 hours had a surface compressive stress of approximately 385MPa and a depth of compression of approximately 12.5 μm. The samples ion exchanged for 16 hours had a surface compressive stress of approximately 360MPa and a depth of compression of approximately 21 μm. This data generally indicates that ion exchange further increases the compressive stress at the surface of the laminated glass article. It is believed that such an increase in surface compressive stress will further enhance the ability of the laminated glass article to withstand defects introduced on the surface without damage.
Referring now to fig. 4, the percentage of weight gain of the ion-exchange enhanced sample is plotted as a function of the square root of the ion-exchange time. Fig. 4 generally shows that the weight gain of all samples of the laminated glass article after ion exchange strengthening is less than 0.4%. The lack of observable warpage or deformation is believed to be due to the low weight gain. Additionally, the data in fig. 4 plus FSM data may indicate that: favorable stress profiles in the sample can be obtained with relatively low amounts of lithium ion toxicity in the molten salt bath.
In particular, as described above, the glass cladding layer and the glass core layer contain lithium ions (from Li)2O) that exchanges with sodium and potassium ions in the molten salt bath, resulting in an increase in surface compressive stress in the glass cladding layer. The weight gain data indicate that relatively little Li is passed+-Na+Or Li+-K+The exchange event may effect an increase in surface compressive stress, resulting in a relatively low weight gain. Thus, a relatively small amount of lithium is removed from the glass, resulting in a relatively low lithium ion toxicity in the molten salt bath.
While not wishing to be bound by theory, it is believed that after a relatively short ion exchange time, the surface compressive stress in the sample increases with a corresponding relatively low weight gain, relatively low bath toxicity, and no observable warpage or deformation attributable to the compressive stress pre-existing in the sample due to lamination.
Samples were also analyzed using electron microprobe analysis techniques to determine Li before and after ion exchange strengthening2O、K2O and Na2The concentration of O varies with depth. The drawn, laminated (i.e., prior to ion exchange) glass cladding has a Na concentration of approximately 4 mol%2O, and drawn laminated (i.e., prior to ion exchange) glassThe core layer has a concentration of approximately 11 mol% Na2And O. FIG. 5 graphically depicts 20% NaNO at 390 deg.C3/80％KNO3Na after ion exchange of the intermediate laminated glass article for 0.5 hour2O and K2The concentration of O is a function of depth from the surface.
The microprobe data depicted in FIG. 5 after ion exchange treatment at 390 ℃ for 0.5 hour indicates that: na occurs during ion exchange2O and K2O diffuses into the glass coating layer to increase Na in the glass coating layer2O and K2The concentration of O is particularly in the region near the surface of the glass cladding layer (i.e., 0 on the x-coordinate close to the coordinate axis depicted in fig. 5). This data also generally indicates: na in the glass coating2The concentration of O decreases with increasing distance from the surface of the laminated glass article (i.e., depth of 0), reaches a minimum at the midpoint of the glass cladding layer thickness, and increases from the midpoint toward the core-cladding interface. Similarly, K2The concentration of O is greatest near the surface and decreases with increasing distance from the surface of the laminated glass article. This data is consistent with FSM data showing an increase in surface compressive stress after ion exchange.
The drawn samples of the laminated glass articles and samples of the laminated glass articles ion exchanged under different conditions were also tested for surface dynamic impact strength according to the surface dynamic impact test procedure described herein. In particular, one set of samples tested in the pulled condition, one set of samples tested 5% NaNO at 390 ℃3/95％KNO3After ion exchange in the molten salt bath of (1) for 2.0 hours, a set of samples was tested at 390 ℃ with 5% NaNO3/95％KNO3After ion exchange in a molten salt bath for 24 hours, a set of samples was tested at 390 ℃ with 20% NaNO3/80％KNO3After ion exchange in the molten salt bath of (1) for 0.5 hours, and a set of samples at 390 ℃ with 20% NaNO3/80％KNO3After 7.5 hours of ion exchange in the molten salt bath of (2). Impact laminating glass with disc-shaped 30-grit SiC sandpaper using the surface dynamic impact test procedure described hereinA sample of the article. The load at each test impact was recorded. If the laminated glass article is not damaged upon impact, the disc-shaped sandpaper is replaced with "fresh" sandpaper and the speed of the piston to which the sandpaper is attached is increased. The process was repeated until the sample was damaged. The impact load at the time of damage was recorded as the "surface dynamic impact strength (surface dynamic impact strength)" of the sample. For comparison purposes, a non-laminated alkali aluminosilicate glass sample strengthened by ion exchange (hereinafter referred to as a "comparative" sample) was also tested to failure. The control sample was also tested to failure as was the laminated glass article.
Figure 5 graphically depicts surface dynamic impact strength at failure as a function of piston velocity for drawn laminated glass articles and control treatments. As shown in fig. 5, the laminated glass article generally had a surface dynamic impact strength of greater than or equal to 400N, while most samples had a surface dynamic impact strength of greater than 500N. However, the non-laminated control sample had a surface dynamic impact strength of 500N or less. Further, fig. 7 graphically depicts the average surface dynamic impact strength of the drawn laminated glass article, the ion-exchanged laminated glass article, and the control sample. As shown in fig. 7, the laminated glass article has a greater average surface dynamic impact strength in both the drawn condition and after ion exchange compared to the control sample.
The drawn samples of the laminated glass article and the samples of the laminated glass article after ion exchange were also tested for edge dynamic impact strength according to the edge dynamic impact test procedure described herein. In particular, one set of samples was tested in the drawn condition, while one set of samples was tested at 390 ℃ with 100% KNO3After 1.0 hour of ion exchange in the molten salt bath of (1). The samples were impacted with a WC stick of 3/8 inches using the edge dynamic impact test procedure described herein. The load at each test impact was recorded. If the laminated glass article is not damaged upon impact, the speed of the piston to which the WC rod body is attached is increased. The process was repeated until the sample was damaged. The impact load at failure was recorded as the "edge dynamic impact Strength (edge dynam) of the sampleic impact strength)”。
Figure 8 graphically depicts the edge dynamic impact strength at failure as a function of plunger velocity for drawn laminated glass articles and ion exchanged laminated glass articles. As shown in fig. 8, the laminated glass article generally had an edge dynamic impact strength of greater than or equal to 300N, while the ion exchanged sample had an edge dynamic impact strength of greater than or equal to 500N. Further, fig. 9 graphically depicts the average edge dynamic impact strength of the drawn laminated glass article and the ion exchanged laminated glass article. As shown in fig. 9, the ion exchanged laminated glass article has a greater average edge dynamic impact strength than the drawn laminated glass article.
Example 2
A three layer laminated glass article was formed from core glass composition C1 (table 1) and clad glass composition CL1 (table 2A). The thickness of the glass cladding layer is approximately 200 to 250 μm. The thickness of the glass core layer is approximately 300 μm. The glass core layer had an elastic modulus of 76.67GPa and a CTE of 84x10-7V. C. The glass cladding layer has an elastic modulus of 67.78GPa and a CTE of 49.6x10-7V. C. The compressive stress in the glass cladding layer due to the CTE mismatch between the glass cladding layer and the glass core layer was determined to be about 66MPa based on the values of the elastic modulus, poisson's ratio, and CTE of each glass. For the purposes of this calculation, Δ T is estimated as the difference between the lower strain point temperature and room temperature.
By immersing a sample of the laminated glass article in 100 wt.% KNO at a temperature of 390 ℃3For 0.5 hours, 1 hour, 2 hours, 4 hours, 8 hours, 16 hours, or 24 hours, respectively, to ion exchange strengthen the sample of the laminated glass article.
After ion exchange strengthening, the Compressive Stress (CS) and depth of compression were measured with a basic stress meter (FSM) instrument. Samples ion exchanged for 0.5 hours had a surface compressive stress of approximately 575MPa and a depth of compression of approximately 5 μm. The sample ion exchanged for 1 hour had a surface compressive stress of approximately 550MPa and a depth of compression of approximately 7 μm. The samples ion exchanged for 2 hours had a surface compressive stress of approximately 525MPa and a depth of compression of approximately 8 μm. The samples ion exchanged for 4 hours had a surface compressive stress of approximately 510MPa and a depth of compression of approximately 12 μm. The samples ion exchanged for 8 hours had a surface compressive stress of approximately 475MPa and a depth of compression of approximately 16 μm. The samples ion exchanged for 16 hours had a surface compressive stress of approximately 470MPa and a depth of compression of approximately 24 μm. The samples ion exchanged for 24 hours had a surface compressive stress of approximately 450MPa and a depth of compression of approximately 28 μm.
This data generally indicates that ion exchange further increases the compressive stress at the surface of the laminated glass article. It is believed that such an increase in surface compressive stress will further enhance the ability of the laminated glass article to withstand defects introduced on the surface without damage. In comparison to example 1 above, this data also shows: compared with 20% NaNO3/80％KNO3Lamination with medium ion exchange at 100% KNO3Ion exchange in (b) substantially increases surface compressive stress and depth of compression.
Example 3
The ion-exchange properties of the glass compositions of the glass core layer and the glass cladding layer indicated in tables 1A, 1B, 2A, and 2B were evaluated to determine the effect of free volume on ion exchange. In particular, 1mm thick coupons of each glass composition were annealed followed by 100% KNO at 410 ℃3For 4 hours in the molten salt bath. After ion exchange, the samples were analyzed using a Fundamental Stress Meter (FSM) instrument to determine the surface compressive stress and depth of compression caused by the ion exchange. The results are recorded in tables 3A, 3B, 4A, and 4B.
Table 3A: ion exchange characteristics of exemplary glass core compositions
Table 3B: ion exchange characteristics of exemplary glass core compositions
Table 4A: ion exchange characteristics of exemplary glass cladding compositions
Table 4B: ion exchange characteristics of exemplary glass cladding compositions
As shown in tables 3A-4B, the glass core compositions achieve higher surface compressive stress, while glasses with lower free volume (i.e., glasses with higher refractive index) exhibit higher compressive stress achieved under the same ion exchange conditions.
Those skilled in the art will appreciate that various modifications and changes may be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the present specification cover the modifications and variations of the various embodiments described herein provided such modifications and variations fall within the scope of the appended claims and their equivalents.
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