# US 2014/0154661 A1 · Durable glass articles for use as writable erasable marker boards

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- Number: US 2014/0154661 A1
- Document ID: US20140154661A1
- Status: Published application
- Kind: A1
- Application number: 14/093,649
- Filed: 2013-12-02
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Corning Incorporated
- Applicants: Corning Incorporated
- Inventors: Dana Craig Bookbinder; Jeffrey John Domey; Matthew Wade Fenton; David Lee Weidman
- Web page: https://patentgrep.com/patent/US20140154661A1

## CPC

- B43L 1/12: having translucent writing surfaces producing visual impressions by co-operation with backing members {(B43L1/008 takes precedence)}
- B32B 17/10: of synthetic resin
- B43L 1/00: Repeatedly-usable boards or tablets for writing or drawing (drawing-boards B43L5/00)
- B43L 1/002: {chemical details}
- B43L 1/008: {with magnetic action}
- B43L 1/126: {withinterposed adhesive substances}
- C03C 3/085: containing an oxide of a divalent metal
- C03C 3/087: containing calcium oxide, e.g. common sheet or container glass
- C03C 3/091: containing aluminium
- C03C 3/093: containing zinc or zirconium
- B43L: ARTICLES FOR WRITING OR DRAWING UPON; {WRITING OR DRAWING AIDS;} ACCESSORIES FOR WRITING OR DRAWING (workshop equipment for marking-out work B25H7/00; teaching hand-writing or drawing G09B11/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS

## Abstract

The invention relates to glass articles suitable for use as writeable erasable marker boards. More particularly, disclosed is a strengthened glass article suitable for use as a writeable erasable marker boards, wherein the glass sheet exhibits an ion exchanged glass having a front surface and a back surface and exhibiting a thickness of less than 2.0 mm and having a depth of layer (DOL) greater than 20 microns and a surface compressive strength of at least 300 MPa. The strengthened glass article exhibits certain optical properties which render it particularly suitable for use as a writeable erasable marker boards electronic including: (1) shadow parallax of less than 1.73/n measured at 60 degree incident light angle and for an index of refraction n; and, (2) a haze of less than 50%. Further disclosed is a markerboard with improved magnetic force attributes; sufficient to hold weak magnets in place.

## Claims

### Claim 1

A writeable erasable marker boards comprising a strengthened glass sheet having a front surface and a back surface wherein the glass sheet exhibits a thickness of less than 2.0 mm, shadow parallax of less than or equal to 1.73/n when measured at a 60 degree incident light angle and for an index of refraction of n, and a transmitted haze of less than 50%.

### Claim 2 (depends on 1)

The writeable eraseable marker board of claim 1 which further includes a magnetic or ferrous steel backing plate positioned on at least one side of the glass sheet such that when the marker board is vertical, a permanent magnet with maximum energy product of less than 10 MGOe will remain attached to the glass sheet through magnetic force only.

### Claim 3 (depends on 1)

The writeable erasable marker board of claim 1 which further includes a magnetic or ferrous steel backing plate positioned on at least one side of the glass sheet such that when the marker board is vertical, a permanent magnet with maximum energy product of less than 5 MGOe will remain attached to the glass sheet through magnetic force only.

### Claim 4 (depends on 1)

The writeable erasable marker board of claim 1 which further includes a magnetic or ferrous steel backing plate positioned on at least one side of the glass sheet such that when the marker board is vertical, a permanent magnet with maximum energy product of less than 1 MGOe will remain attached to the glass sheet through magnetic force only.

### Claim 5 (depends on 1)

A writeable eraseable marker board of claim 1 wherein the marker board further includes an organic film structure which is laminated to at least one side of the glass sheet which provides anti-splinter functionality.

### Claim 6 (depends on 1)

A writeable eraseable marker board of claim 1 wherein the marker board further includes a decorative layer is attached to at least one side of the glass sheet.

### Claim 7 (depends on 1)

The writeable erasable marker board of claim 1 wherein the strengthened glass article further exhibits a fracture toughness of greater than 0.75 MPa·m½, an abraded MOR of greater than 350 MPa, a Vickers hardness of at least 600 kgf/mm2, a Young's Modulus of greater than 60 GPa, and a surface compressive stress of greater than 300 MPa

### Claim 8 (depends on 1)

The writeable erasable marker board of claim 1, wherein the strengthened glass sheet has a thickness less than 2.0 mm and a surface compressive strength of at least 300 MPa.

### Claim 9 (depends on 1)

The writeable erasable marker board of claim 1, wherein the strengthened glass sheet has at least one compressively-stressed region near the front surface or the back surface, and wherein the compressively-stressed region has a layer depth of at least 20 microns.

### Claim 10 (depends on 1)

The writeable erasable marker board of claim 1, wherein the strengthened glass sheet has a thickness that is selected from the group consisting of less than 2.0 mm, less than 1.0 mm, and less than 0.7 mm.

### Claim 11 (depends on 1)

The writeable erasable marker board of claim 1, wherein the strengthened glass has an distinctness-of-reflected image (DOI) of less than 95.

### Claim 12 (depends on 1)

The writeable erasable marker board of claim 1, wherein the strengthened glass has an RMS roughness in a range from about 50 nm up to about 500 nm, a distinctness of image (DOI) of less than about 85 and a transmission haze of less than 40%.

### Claim 13 (depends on 1)

The writeable erasable marker board of claim 1, wherein the strengthened glass article exhibits an MOR of greater than 475 MPa.

### Claim 14 (depends on 1)

The writeable erasable marker board of claim 1 further comprising a mounting means, wherein the mounting means is selected from the group consisting of (i) a magnetic layer on the back surface of the strengthened glass sheet, (ii) an adhesive layer on the back surface of the strengthened glass sheet, and (iii) a static cling layer on the back surface of the strengthened glass sheet.

### Claim 15 (depends on 1)

The writeable erasable marker board of claim 1 further comprising a mounting means, wherein the mounting means is selected from the group consisting of (i) one or more mounting holes formed in the strengthened glass sheet, (ii) one or more glass sheet hanging elements attached to the strengthened glass sheet, and (iii) one or more glass sheet framing elements attached to the strengthened glass sheet.

### Claim 16 (depends on 1)

The writeable erasable marker board of claim 1 wherein the glass is an ion-exchanged alkali-aluminosilicate glass comprising, in weight percent as oxides on a batched basis, 40-80% SiO2, 0-28% Al2O3, 0-8% B2O3, 0-18% Li2O, 0-10% Na2O, 0-11% K2O, 0-16% MgO, 0-18% CaO, 0-15% CaF2, 0-20% SrO, 0-12% BaO, 0-8% ZnO, 0-20% P2O5, 0-8% TiO2, 0-5% ZrO2, 0-1% SnO2 and 0-1 Sb2O3, 0-1% As2O3 .

### Claim 17 (depends on 1)

The writeable erasable marker board of claim 1, wherein the glass is an ion-exchanged alkali-aluminosilicate glass comprising : 60-70 mol % SiO2; 6-14 mol % Al2O3; 0-15 mol % B2O3; 0-15 mol % Li2O; 0-20 mol % Na2O; 0-10 mol % K2O; 0-8 mol % MgO; 0-10 mol % CaO; 0-5 mol % ZrO2; 0-1 mol % SnO2; 0-1 mol % CeO2; less than 50 ppm As2O3; wherein 12 mol %≦Li2O+Na2O+K2O≦20 mol % and 0 mol %≦MgO+CaO≦10 mol %.

### Claim 18 (depends on 1)

The writeable erasable marker board of claim 1 wherein the glass is an ion-exchanged alkali-aluminosilicate glass comprising at least 50 mol % SiO2, less than 10 mol % B2O3, and at least 8 mol % Na2O, wherein the aluminoborosilicate glass is ion exchangeable, wherein a ratio
Al
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O
3
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+
B
2
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∑
modifiers
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wherein Al2O3(mol %)>B2O3(mol %) and the modifiers are Na2O and, optionally, at least one oxide selected from the group consisting of alkali metal oxides R2O other than Na2O and alkaline earth oxides RO, wherein the aluminoborosilicate glass has a Young's modulus of less than about 69 GPa, and wherein −6 mol %<Σmodifiers−Al2O3<3 mol %.