WO1995018016A1

WO1995018016A1 - Glass tile

Info

Publication number: WO1995018016A1
Application number: PCT/US1994/014435
Authority: WO
Inventors: Henry E. Lowe; Todd Fitzgerald; Clayton C. Nelson
Original assignee: Lowe Henry E
Priority date: 1993-12-30
Filing date: 1994-12-30
Publication date: 1995-07-06

Abstract

A glass tile having good structural strength, good color intensity, reduced brittlensess and an outstanding range of visual interes made by preparing a colored or color coated glass inset layer (10), sandwiching the glass inset layer (10) between top (12) and base (14) flat glass layers, and heating the sandwich to a temperature sufficient to fuse the three layers.

Description

GLASS TILE

BACKGROUND

This invention relates to tiles used to construct floor, wall and countertop coverings,

and art objects, and more specifically to unique glass tiles with unusual visual and

physical properties.

Tiles made of ceramics and porcelain are used to construct floor, wall and

countertop coverings, as well as art objects. Unfortunately, the range, intensity, and brilliance of color attainable in such tiles is often less than that sought by the designer or the artisan. Also, the processes by which such conventional ceramic and porcelain tiles are produced and their crystalline structures limit the range of visual effects which can be obtained. Various types of clear and colored glass are in use today in both practical and aesthetic applications ranging, for example, from simple windows, to stained glass

windows, to mirrors. The optical properties of glass, including reflectivity, transparency,

translucency, opaqueness, as well as the stability, rigidity, and abrasion resistance, are responsible for its widespread use. Unfortunately, however, glass has not heretofore been

successfully used in making tiles for use as wall, floor and countertop coverings because visual interest superior to ceramics and porcelain has not been achievable in any easy,

reliable and repeatable way, and because glass typically is brittle and forms dangerous shards on cutting or breaking.

If the unique visual properties of glass could be adapted to tiling applications by relatively simply and reliably making glass tiles with improved structural strength and color intensity, reduced brittleness, and an outstanding range of visual interest, an important

contribution would be at hand. SUMMARY

This invention satisfies the above needs by providing a novel glass tile in which outstanding visual interest and intense brilliant color can be obtained along with good

structural strength and ease of cutting substantially without shard formation. The glass tiles of the present invention may be made by preparing a glass inset layer, sandwiching the inset layer between top and base flat glass layers and fusing the three layers.

DRAWINGS

The features, aspects and advantages of the present invention will become better

understood with reference to the following description, the appended claims and the

accompanying drawings where:

FIGURE 1 is a front elevation view showing the glass inset layer sandwiched

between the top and base flat glass layers, before fusing;

FIGURE 2 is a front elevation view of the glass inset layer sandwiched between the top and base flat glass layers, after fusing; and FIGURE 3 is a perspective view of ai vacuum chamber with a crucible containing a metallic oxide being heated to a temperature sufficient to convert it to an ionized state and a glass substrate onto which the ionized metal is being coated.

DESCRIPTION The present invention is directed to a glass tile made by: 1 ) Preparing a glass inset layer 1 0 which is either made of colored glass or has a colored surface,

2) Sandwiching the glass inset layer between top flat glass layer 12 and base flat glass layer 14, and

3) Heating the resulting sandwich 16 to a temperature sufficient to fuse the 3 layers to produce a unitary product 18.

The glass inset layer and the top and base flat glass layers, as well as the fusing process,

are described below.

The Flat Glass Outer Layers

Flat glass outer layers 12 and 14 must be made of a glass composition compatible

with glass inset layer 10, in that the material of the flat glass and of the inset must have the same coefficients of linear expansion. More particularly, the coefficient of linear

expansion of the flat glass layers should be between about 87 and 92 and, in order to

maintain compatibility with the glass inset layer, chosen so that in a particular tile the coefficient of expansion of the fiat glass layers will be within about + 1 % of the coefficient of linear expansion of the inset glass layer.

The flat glass layers may be clear or colored and may be made of any conventional glass compound. Soda-lime-silica glass is the preferred material for the flat glass layers. The flat glass layers may be of any commercially available thickness which will permit fusing. It is preferred, however, that the top and base glass layers be in the range of

about 1 .5 to 2.5 mm in thickness and that the top glass layer be thinner than the base glass layer and equal in thickness or slightly thinner than the inset layer. More

particularly, the thickness of the inset layer should be about 25 to 100% of the thickness of the base layer and preferably about 50 to 75% of the thickness of the base layer. The thickness of the top layer should be about 25 to 100% of the thickness of the inset layer

and preferably about 50 to 75% of the thickness of the inset layer. This preferred

arrangement insures during fusing a proper fluid draping of the top glass layer around the

inset layer as well as uniform contact and fusing to the base layer, as illustrated at 20 in

FIG. 2. Thus, in order to make a tile comparable in thickness to that of a conventional

ceramic tile (roughly 6mm + 10%), a preferred base layer 14 would be about 2mm in

thickness, a preferred inset layer 10 would be about 2-2.5mm in thickness, and a preferred top layer 12 would be about 1.6mm in thickness. Finally, the three layers should be close to the same size, that is, their perimeters

should generally coincide when the sandwich is formed. In a preferred embodiment, as

illustrated in FIG. 1 , the perimeter of the inset layer should be offset so that it lies slightly

inside of the perimeter of the outer layers. The optimal offset, however, must be determined on a case-by-case basis, to insure that the top glass layer properly drapes

around the inset as illustrated at 20 in FIG. 2.

The shape and dimensions of the final glass tile will of course be determined by the shape and dimensions of the layers from which it is made. Typically, the final glass tile will be square or rectangular, although other shapes may be made. Also, the size of the tile will 20 be determined by the nature of the intended application. The Inset Layer

The inset layer may be made either of colored glass having a single color or multiple patterns, or of glass onto which a single color or a colored pattern has been

coated. In all cases, it is important that the inset be primarily made of glass in order to ensure that the proper structural properties are achieved in the final glass tile. Preferably, the inset is a single flat piece although it may comprise separate smaller pieces, glass frit or even metal oxide colors, such as those listed below in Table 1.

Colored glass inset layer When colored glass is used in the inset layer, it may comprise conventional stained glass. In a preferred embodiment, however, a particularly brightly colored and visually interesting single or multiple piece inset will be prepared in a process comprising the steps

of compounding a glass frit mixture, casting, trimming and firing, as described below.

1 . Glass frit and a coloring ingredient comprising an inorganic oxide are combined

with a non-aqueous fluid to form a homogenous mixture. The term "glass frit" refers herein to powdered glass or finely ground inorganic minerals mixed with fluxes and

coloring agents which turn into a glass or enamel on heating. The glass frit should be

ground to a size such that at least about 98% would pass through from a 60 to a 600 mesh U.S. standard screen, in a preferred embodiment, at least about 98% would pass through a 200 mesh U.S. standard screen.

The coloring agent will be a metallic oxide preferably chosen from among oxides of the metals set out in Table I below:

TABLE I

Color Metallic Oxide

Blue Co-Cr-Al

Yellow Cd-Zn

Orange, Light Red, Cd-Zn-Se

Medium Red and Dark Red

Green Cr

Blue Co-Al

Turquoise Co-Cr-Zn-Al

Black Cl-Fe-Cr

Pink Cr-Sn-Ca-Si

Blue Co-S i

B Pink Au

Blue Co-Cr-Al

Yellow Pb-Sb-Zn

Black Cu-Cr

Brown Cr-Fe-Zn-Sb-Zr-Si

Green Co-Cr-Al

Blue Co-Cr-Al

Brown Cr-Fe-Zn-Ni-Zr

Brown Cr-Fe-Zn

Yellow Cr-Sb-Ti

Yellow Ni-Sb-Ti

Black Cu-Cr

G ray V-Sb-Si-Ti

Pink Cr-Sn-Ca-Si

The non-aqueous fluid used in preparing the mixture may comprise an organic

solvent extender, a binder, and a plasticizer. The levels on a percent by weight basis

of glass frit, coloring agent and non-aqueous fluid components preferably lie in the

following ranges:

Ingredient Preferred Most Preferred

Glass frit 60-80 75-80

Coloring ingredient .05-2.0 0.1-1.5

Solvent extender 7.0-3.0 14-25

Binder 3.0-5.5 4.0-5.0

Plasticizer 4.5-8.5 5.5-7.0

Useful organic solvent extenders include methyl ethyl ketone, toluene, dimethyl

sulfoxide, mono- and dialkyl ethers of ethylene glycol, and alcohols. Methyl ethyl

ketone and toluene may be used in combination in a preferred organic solvent extender

in which it is further preferred that at least 5% by weight of the combination be methyl

ethyl ketone. In certain cases, the solvent extender may have to be adjusted to achieve

workable fluidity.

The binder will comprise a high molecular weight polyacrylate, a high molecular

weight polymethacrylate, or a high molecular weight polyvinyl resin, with

polymethacrylate being preferred. One particularly preferred high molecular weight

polymethacrylate is Rhome & Haas' B-66.

Finally, the plasticizer may be any commonly available organic compound typically

added to the high molecular weight polymer of choice to facilitate processing and to

increase the flexibility and toughness of the final product by internal modification (solvation) of the polymer molecule. For example, among the more important

plasticizers are nonvolatile organic liquids and low-melting solids, e.g., ethylene glycol

and its derivatives, tricresol phosphate, castor oil, etc. A preferred plasticizer for the

preferred polymethacrylate binder is dioctyl phthalate.

In one preferred embodiment, the mixture will comprise on a percent by weight

basis:

MATERIAL

Glass frit 76.4

Coloring ingredient 0.5

Toluene 14.8

Methyl ethyl ketone 1.3

Methacrylate polymer 4.4

Dioctyl phthalate 2.6

The ingredients are formed into a homogenous mixture by mixing at ambient

temperature in any conventional mixing device such as a ball mill, sand mill, pebble

mill, homogenizer or high speed mixer.

2. The homogenous mixture of step 1 is placed into a gravity-feed container and

then dropped onto a release surface, such as a waxed, varnished or teflon-coated surface.

The mixture forms a flat "mat" on this surface of a width determined primarily by the

rate of flow onto the release surface and optionally by nips which confine the outer

edges of the mat. The mat is passed under a doctors' knife to insure uniform thickness. It is then

permitted to cure by standing as the organic solvents are released and the mat becomes

highly thixotropic and then rubber-like.

Fans or other means to create air turbulence parallel and adjacent the surface of

the mat may be used to accelerate solvent escape and curing after the doctors' knife has

passed over the mat. Air turbulence adjacent and directed against the surface of the mat

can also create visually interesting color patterns in the final product due to locally rapid

solvent release. Such air movement early in the curing process can also alter color

patterns since coloring agents will be shuttled around in the wet mat.

3. When sufficiently rubber-like to cut, the mat is cut to the desired size

and permitted to continue curing over about a 24-hour period after which it is fired on

a gradient temperature profile from ambient to about 1200 to 1330°F and preferably to

about 1250 to 1270°F. The material is "soaked" or held at that temperature for from

about 5 to 30 minutes and preferably for about 15 minutes to drive off the balance of the solvent and finish the curing of the glass inset layer.

Coated glass inset layer

The colored glass inset 10 can be made by applying a conventional inorganic coating

capable of withstanding firing to a glass substrate.

In a preferred embodiment, a metallic ionized coating will be applied to the glass

substrate to produce a mirror-like finish of a single transmitted color or multiples thereof

and a dichroic effect in the final glass tile. Also, multiple ionized coatings may be

applied to produce a finish which transmits different colors for each coating, depending on the angle of light refraction.

The metallic coating is produced by ionizing and applying a metal oxide to a glass

substrate 28 in a vacuum chamber 20 pulling at least about 1 to 2 atmospheres of

vacuum. The metal oxides may be chosen from those known in the art including oxides

of the metals set out in Table 11 below.

TABLE II

Color Metallic Oxide

Blue Co

Yellow Cd

Green Cr

The metallic oxide is placed in a crucible 24 in the vacuum chamber and heated

with a laser 26 or other heat source to a temperature sufficient to convert it to an

ionized state. The glass substrate, which is supported on a turntable 30, may be at

ambient or it may have to be heated to achieve a satisfactory bond (typically up to about

700°F and preferably about 350-500°F), depending on the metallic oxide being used.

Typically, once the metallic oxide material is ionized, it will be allowed to deposit on

the glass substrate over a period of from about 15 minutes to 1.5 hours, depending on

the desired thickness of the coating. The glass substrate is rotated slowly (i.e., at about

30-60 rpm) during the deposition process in order to insure uniform deposition. When an inset layer prepared as just described is sandwiched and fused between

the base and top glass layers, the expansion and contraction of the glass as well as the

slightly different rates of expansion and contraction of the metallic coatings results in

a generally reproducible unique grainy appearance and random patterns.

Forming the Sandwich

Sandwich 16 with base layer 14, inset layer 10 and top layer 12 is formed as

depicted in FIG. 1 by simply placing each layer onto the layer below it, as depicted in

FIG. 1. If desired, a fine layer of an oil such as castor oil may be coated onto the

abutting surfaces to provide tackiness and prevent slippage. Actually, any oil or other

agent which 10 provides tackiness and is driven off during the fusing step without

leaving a deposit may be used.

Fusing, the Sandwich

Once sandwich 16 is formed, it is placed in an oven and fired from ambient on a

gradient temperature profile up to about 1425-1470°F and preferably up to about 1450°F. The sandwich is soaked at that temperature for from about 5-30 minutes and

preferably for about 15 minutes.

The sandwich is then rapidly cooled by the introduction of air, passing through the

annealing stage at about 1100°F downward to 500°F at a rate of about 20-25

Fahrenheit degrees per minute. Then it is slowly cooled to ambient temperature. The

final product is a fully fired, tempered glass tile 18. In an alternate embodiment, an

untempered tile 18 can be produced by rapidly cooling to the annealing temperature,

soaking for from about 5 to 30 minutes and preferably for about 15 minutes and then slowly cooling down to ambient.

The following examples are intended to illustrate the practice of the present

invention. These examples are not intended to be exhaustive or limiting of the

invention.

EXAMPLES

1. A glass tile was prepared from a sandwich comprising 4-inch square soda-lime-

silica clear glass base and top layers. The base layer was about 2mm in thickness and

the top layer was about 1.6mm in thickness. An inset layer about 2.5mm in thickness

was placed between the base and top layers.

The inset layer was prepared by combining glass frit having a particle size small

enough so that at least 98% would pass through a 200 mesh U.S. standard screen with

Co-Cr-Al, as a coloring ingredient. The frit and coloring agent were combined with an

organic solvent extender, a plasticizer, and a binder in weight percentages as follows:

MATERIAL

Frit . 76.4

Co-Cr-Al 0.5

Toluene 14.8

Methyl ethyl ketone 1.3

Methacrylate polymer 4.4

Dioctyl phthalate 2.6 The above mixture was formed into a homogenous mixture in a ball mill, placed into

a gravity-feed container, and dropped onto a teflon-coated surface to form a flat mat.

The mat was passed under a doctor's knife while being subjected to air turbulence under

a fan.

When the mat became sufficiently rubber-like to cut, it was cut into 4-inch squares

and then permitted to continue curing over a 24-hour period. After this, the 4-inch

squares were fired at a gradient temperature profile to about 1250-1270°F. The fired

pieces were soaked for about 15 minutes and then cooled to ambient temperature.

The above inset layer was placed between the base and top layers and fired on a

gradient temperature profile to about 1450°F and held at that temperature for about 15

minutes. Fans were then used to drive the temperature downward to about 500°F at a

rate of about 20-25 degrees Fahrenheit per minute and then cooled slowly to ambient

temperature. The final product was a fully fired, tempered glass tile with brilliant blue

color.

2. A glass tile was prepared in accordance with the procedure described in

example 1, except that a different inset was used. The inset, in this example, was

prepared by placing a glass substrate in a vacuum chamber pulling about 2 atmospheres

of vacuum. C0₂0₃ was provided in a crucible positioned within the vacuumed chamber.

The C0₂0₃ was heated with a laser to about 700-800°F to convert to an ionized state

whereupon it was allowed to deposit on the glass substrate over a period of about I

hour. The coated substrate was then used as the inset to prepare a bright blue glass tile.

3. Tiles prepared in accordance with the procedure of examples 1 and 2 above were subjected to ASTM procedures and compared to industry standards, with results

set out below in Table 111. These industry standards are believed to exceed average

characteristics of commercial ceramic tiles.

TABLE III

GLASS

ASTM CERAMIC TILE TILE TEST

TEST NAME PROCEDURE STANDARD RESULTS

Water Absorption C-373 0.5% (Impervious) 0.00

Bond Strength C-482 50 psi 122 psi

Thermal Shock C-484 No Disintegration No Disintegralion

Warpage (Edge) C-485 1.00% 0.12%

Warpage (Diagonal) C-485 0.75% 0.16%

Facial Dimensions C-499 3.0% Individual 1.14%

1.5% Range CV=0.9188%

Thickness Range C-499 0.04" 0.011"

Abrasive Hardness C-501 100 122

Wedging C-502 1.0% 0.884%

Chemical Resistance C-650 Alkali (10% KOH) Unaffected

Acid (10% HCL) Unaffected

Modulus of Rupture C-674 1,000 psi 9,420 psi

Knoop Hardness C-730 None 9

Frost Resistance C-1026 No Chipping, Flawless

0.50 All Conditions 0.65

While particular embodiments in the invention have been shown and described,

it will be obvious to those skilled in the art that various changes and modifications may

be made therein without departing from the spirit and scope of the invention. Therefore,

it is intended in the appended claims to cover all such changes and modifications which

fall within the true spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A glass tile comprising:

a glass inset layer fused between flat glass top and base layers, the flat

glass layers having a coefficient of linear expansion of between about 87 and 92 and

5 being within about + 1 % of the coefficient of linear expansion of the inset layer.

2. 2. The glass tile of claim 1 wherein the flat glass layers are clear.

3. 3. The glass tile of claim 1 wherein the flat glass layers are colored.

4. 4. The glass tile of claim 1 wherein the flat glass layers are soda-lime-silica

glass.

0 5. The glass tile of claim 1 wherein the flat glass layers are from about 1.5

to 2.5 mm in thickness.

6. The glass tile of claim 1 wherein the top layer is thinner than the base

layer and equal in thickness or thinner than the inset layer.

7. The glass tile of claim 1 wherein the top layer is about 50 to 75% of the

5 thickness of the base layer and about 50 to 75% of the thickness of the inset layer.

8. The glass tile of claim 1 in which the base layer is about 2 mm in

thickness, the inset layer is about 2-2.5 mm in thickness and the top layer is about

1.6 mm in thickness.

9. The glass tile of claim 1 in which the perimeters of the top and base

0 layers generally coincide and the perimeter of the inset layer is offset from the

perimeters of the top and base layers.

10. The glass tile of claim 1 in which the inset layer is made of colored

glass.

11. The glass tile of claim 1 in which the inset layer is made of glass onto

which a single color or a color pattern has been coated.

12. The glass tile of claim 1 in which the inset layer is a single flat piece.

13. The glass tile of claim 1 in which the inset layer comprises separate

smaller pieces.

14. The glass tile of claim 1 in which the inset layer is made up of

powdered glass.

15. The glass tile of claim 1 in which the inset layer is made up of metal

oxide colors.

16. The glass tile of claim 1 in which the inset layer is prepared by:

a) forming a homogenized mixture of glass frit ground to a size such that

at least 98% would pass through from a 60 to a 600 mesh U.S. Standard

Screen with a coloring ingredient comprising an inorganic oxide and a

non-aqueous fluid comprising an organic solvent extender, a binder and

a plasticizer,

b) forming a mat of the homogenized mixture on a release surface and

permitting the mat to stand until it becomes rubber-like,

c) cutting the mat to the desired size and permitting it to cure, and

d) firing on a gradient temperature profile to about 1200-1330°F for from

about 5 to 30 minutes.

17. The glass tile of claim 16 in which the glass frit is ground to a size such

that 98% would pass through a 200 mesh U.S. Standard screen.

18. The glass tile of claim 16 in which the metallic oxide is chosen from among

oxides of the group consisting of:

Co-Cr-Al

Cd-Zn

Cd-Zn-Se

Cr

Co-Al Co-Cr-Zn-Al

Cl-Fe-Cr

Cr-Sn-Ca-Si

Co-S i

Au Co-Cr-Al

Pb-Sb-Zn

Cu-Cr

Cr-Fe-Zn-Sb-Zr-Si

Co-Cr-Al Co-Cr-Al

Cr-Fe-Zn-Ni-Zr

Cr-Fe-Zn

Cr-Sb-Ti Ni-Sb-Ti

Cu-Cr

V-Sb-Si-Ti

Cr-Sn-Ca-Si

19. The glass tile of claim 16 in which the organic solvent is chosen from the

group consisting of methyl ethyl ketone, toluene, dimethyl sulfoxide, glycol ethyl

ether and alcohols.

20. The glass tile of claim 16 in which the homogenized mixture comprises:

Glass frit 76.4%

Coloring ingredient 0.5%

Toluene 14.8%

Methyl ethyl ketone 1.3%

Methacrylate polymer 4.4 %

Dioctyl phthalate 2.6 %

21. The glass tile of claim 16 in which the binder is chosen from the group

consisting of high molecular weight polyacrylate, high molecular weight

polymethacrylate, or high molecular weight polyvinyl resin.

22. The glass tile of claim 16 in which the plasticizer is chosen from the group

consisting of ethylene glycol and its derivatives, tricresly phosphate, castor oil.

23. The glass tile of claim 16 in which air turbulence in created adjacent the

surface of the mat during the curing process.

24. The glass tile of claim 16 in which the firing step is conducted on a gradient

temperature profile from ambient to about 1250-1270'F and held there for about 15

minutes.

25. The glass tile of claim 1 in which the glass inset comprises a glass substrate

having an inorganic coating.

26. The glass tile of claim 1 in which the glass inset comprises a glass substrate

having a metallic ionized coating.

27. The glass tile of claim 26 in which the glass inset is made by placing a

glass substrate and a metallic oxide in a vacuum chamber, pulling at least about 1-2

atmospheres of vacuum, heating the metallic oxide to a temperature sufficient to convert

it to an ionized state, and then allowing the ionized material to deposit on the glass

substrate over a period of at least about 15 minutes.

28. A method making a glass tile comprising:

forming a sandwich having an inset layer between a base layer and a top

layer in which the three layers are made of glass, and in which the top and base layers

have a coefficient and expansion between about 87 and 92 and the top and base layers

have a coefficient of expansion within about 1 % of the coefficient of expansion of the

inset layer; and

firing the sandwich on a temperature gradient profile from ambient and

holding to about 1425-1470°F and holding for about 5-30 minutes; and

cooling the sandwich.

29. The method of claim 28 in which the firing is conducted on a temperature

profile from ambient to about 1450°F and held at that temperature for about 15 minutes.

30. The method of claim 28 in which the cooling is at a rate of temperature

drop of about 20-25 Fahrenheit degrees per minute until 500°F is reached, whereupon

the cooling is permitted to proceed slowly to ambient temperature.