U.S. patent application number 15/873188 was filed with the patent office on 2018-05-24 for method for localized annealing of chemically strengthened glass.
The applicant listed for this patent is CORNING INCORPORATED. Invention is credited to Thomas Michael Cleary, Mark Stephen Friske, Robert Stephen Wagner.
Application Number | 20180141846 15/873188 |
Document ID | / |
Family ID | 51454987 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180141846 |
Kind Code |
A1 |
Cleary; Thomas Michael ; et
al. |
May 24, 2018 |
METHOD FOR LOCALIZED ANNEALING OF CHEMICALLY STRENGTHENED GLASS
Abstract
A method for making a laminate structure comprising a first
glass layer, a second glass layer, and at least one polymer
interlayer intermediate the first and second glass layers. The
first glass layer can be comprised of a strengthened glass having a
first portion with a first surface compressive stress and a first
depth of layer of compressive stress and a second portion with a
second surface compressive stress and a second depth of layer of
compressive stress. In other embodiments, the second glass layer
can be comprised of a strengthened glass having a third portion
with a third surface compressive stress and a third depth of layer
of compressive stress and a fourth portion with a fourth surface
compressive stress and a fourth depth of layer of compressive
stress.
Inventors: |
Cleary; Thomas Michael;
(Elmira, NY) ; Friske; Mark Stephen; (Campbell,
NY) ; Wagner; Robert Stephen; (Corning, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CORNING INCORPORATED |
Corning |
NY |
US |
|
|
Family ID: |
51454987 |
Appl. No.: |
15/873188 |
Filed: |
January 17, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14913890 |
Feb 23, 2016 |
9908805 |
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PCT/US14/52037 |
Aug 21, 2014 |
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15873188 |
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61869962 |
Aug 26, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 17/10788 20130101;
C03C 23/0025 20130101; C03C 23/0065 20130101; B32B 17/10743
20130101; B32B 17/1077 20130101; B32B 17/10137 20130101; B32B
17/10761 20130101; B32B 2605/00 20130101; B32B 17/10091 20130101;
C03B 25/08 20130101; C03C 21/00 20130101 |
International
Class: |
C03B 25/08 20060101
C03B025/08; B32B 17/10 20060101 B32B017/10; C03C 23/00 20060101
C03C023/00; C03C 21/00 20060101 C03C021/00 |
Claims
1-43. (canceled)
44. A method of providing locally annealed regions for a glass
article comprising: (a) providing a strengthened glass article
having a first surface compressive stress and a first depth of
layer of compressive stress; (b) targeting first portions of the
glass article on a first side thereof; (c) annealing the targeted
first portions to a second surface compressive stress and a second
depth of layer of compressive stress; and (d) repeating steps (b)
and (c) to create a pattern of annealed portions of the glass
article on the first side thereof.
45. The method of claim 44, wherein the second surface compressive
stress and the second depth of layer of compressive stress are less
than the first surface compressive stress and the first depth of
layer of compressive stress, respectively.
46. The method of claim 44, wherein the step of annealing further
comprises focusing a laser on the targeted first portions for a
predetermined energy density and dwell time to avoid inducing
damage to the glass article.
47. The method of claim 44, wherein the step of annealing further
comprises selectively heating the targeted first portions using
microwave energy.
48. The method of claim 44, wherein the step of annealing further
comprises selectively heating the targeted first portions using an
induction source.
49. The method of claim 44, further comprising the steps of: (i)
targeting third portions of the glass article on a second side
thereof; (ii) annealing the targeted third portions to a third
surface compressive stress and a third depth of layer of
compressive stress; and (iii) repeating steps (i) and (ii) to
create a pattern of annealed portions of the glass article on the
second side thereof.
50. The method of claim 49, wherein the second surface compressive
stress and the third surface compressive stress are different.
51. The method of claim 49 wherein the second depth of layer of
compressive stress and the third depth of layer of compressive
stress are different.
52. The method of claim 44, wherein the strengthened glass article
includes one or more glass layers and an interlayer.
Description
[0001] This application claims the benefit of priority to U.S.
Provisional Application No. 61/869,962 filed on Aug. 26, 2013 the
content of which is incorporated herein by reference in its
entirety.
BACKGROUND
[0002] Glass laminates can be used as windows and glazing in
architectural and vehicle or transportation applications, including
automobiles, rolling stock, locomotive and airplanes. Glass
laminates can also be used as glass panels in balustrades and
stairs, and as decorative panels or coverings for walls, columns,
elevator cabs, kitchen appliances and other applications. As used
herein, a glazing or a laminated glass structure can be a
transparent, semi-transparent, translucent or opaque part of a
window, panel, wall, enclosure, sign or other structure. Common
types of glazing that are used in architectural and/or vehicular
applications include clear and tinted laminated glass
structures.
[0003] Conventional automotive glazing constructions include two
plies of 2 mm soda lime glass with a polyvinyl butyral (PVB)
interlayer. These laminate constructions have certain advantages,
including low cost and a sufficient impact resistance for
automotive and other applications. However, because of their
limited impact resistance and higher weight, these laminates
exhibit poor performance characteristics, including a higher
probability of breakage when struck by roadside debris, vandals and
other objects of impact as well as well as lower fuel efficiencies
for a respective vehicle.
[0004] In applications where strength is important (such as the
above automotive application), the strength of conventional glass
can be enhanced by several methods, including coatings, thermal
tempering, and chemical strengthening (ion exchange). Thermal
tempering is conventionally employed in such applications with
thick, monolithic glass sheets, and has the advantage of creating a
thick compressive layer through the glass surface, typically 20 to
25% of the overall glass thickness. The magnitude of the
compressive stress is relatively low, however, typically less than
100 MPa. Furthermore, thermal tempering becomes increasingly
ineffective for relatively thin glass, e.g., less than about 2
mm.
[0005] In contrast, ion exchange (IX) techniques can produce high
levels of compressive stress in the treated glass, as high as about
1000 MPa at the surface, and is suitable for very thin glass. Ion
exchange techniques, however, can be limited to relatively shallow
compressive layers, typically on the order of tens of micrometers.
This high compressive stress can result in very high blunt impact
resistance, which might not pass particular safety standards for
automotive applications, such as the ECE (UN Economic Commission
for Europe) R43 Head Form Impact Test, where glass is required to
break at a certain impact load to prevent injury. Conventional
research and development efforts have been focused on controlled or
preferential breakage of vehicular laminates at the expense of the
impact resistance thereof.
[0006] For certain automobile glazings or laminates, e.g.,
windshields and the like, the materials employed therein must pass
a number of safety criteria, such as the ECE R43 Head Form Impact
Test. If a product does not break under the defined conditions of
the test, the product would not be acceptable for safety reasons.
This is one reason why windshields are conventionally made of
laminated annealed glass rather than tempered glass.
[0007] Tempered glass (both thermally tempered and chemically
tempered) has the advantage of being more resistant to breakage
which can be desirable to enhance the reliability of laminated
automobile glazing. In particular, thin, chemically-tempered glass
can be desirable for use in making strong, lighter-weight auto
glazing. Conventional laminated glass made with such tempered
glass, however, does not meet the head-impact safety requirements.
One method of forming a thin, chemically-tempered glass compliant
with head-impact safety requirements can be to perform a thermal
annealing process after the glass is chemically-tempered. This has
the effect of reducing compressive stress of the glass thereby
reducing the stress required to cause the glass to break. A
disadvantage of this method is the reduction of compressive stress
occurs in all areas of the glass product rather than in the area of
the glass where the head impact is most likely to occur.
[0008] Thus, there is a need to perform localized annealing in
controlled areas of the glass whereby a resulting product would
retain its strength in critical areas, e.g., near the edges
thereof, and be weakened in the areas important to occupant
safety.
SUMMARY
[0009] The embodiments disclosed herein generally relate to methods
for producing ion exchanged glass, e.g., glass having
characteristics of moderate compressive stress, high depth of
compressive layer, and/or desirable central tension. Additional
embodiments provide automobile glazings or laminates having
laminated, tempered glass.
[0010] In accordance with one or more embodiments herein, methods
and apparatus provide for a thin glass article having a layer of
surface compression from ion exchange techniques which enables
scratch and impact resistance. The glass article can also exhibit a
relatively high depth of compressive layer (DOL), making it
resistant to environmental damage. Notably, the compressive stress
(CS) at the glass surface in certain areas can be lower than in
traditional ion exchanged glass, which allows the glass to pass
automotive impact safety standards (such as the ECE R43 head form
impact test) and is therefore suitable for automotive glazing
applications.
[0011] Additional embodiments provide an exemplary method to cause
a directed thermal annealing and thereby local weakening of a
thermally-tempered or chemically-tempered glass article. One
exemplary embodiment utilizes a laser for such directed thermal
annealing whereby the laser locally heats the glass sufficiently to
cause thermal annealing, but laser exposure is managed to limit
cracking or other physical damage to the glass. A further exemplary
embodiment includes a directed microwave or induction heating to
create a desirable localized thermal annealing.
[0012] Some embodiments of the present disclosure provide a method
of providing locally annealed regions for a glass article. The
method includes providing a strengthened glass article having a
first surface compressive stress and a first depth of layer of
compressive stress and targeting first portions of the glass
article on a first side thereof. The method also includes annealing
the targeted first portions to a second surface compressive stress
and a second depth of layer of compressive stress and repeating
steps the targeting and annealing to create a pattern of annealed
portions of the glass article on the first side thereof.
[0013] Additional embodiments of the present disclosure provide a
laminate structure having a first glass layer, a second glass
layer, and at least one polymer interlayer intermediate the first
and second glass layers. The first glass layer can be comprised of
a strengthened glass having a first portion with a first surface
compressive stress and a first depth of layer of compressive stress
and a second portion with a second surface compressive stress and a
second depth of layer of compressive stress.
[0014] Further embodiments of the present disclosure provide a
laminate structure having a first glass layer, a second glass
layer, and at least one polymer interlayer intermediate the first
and second glass layers. The first glass layer can be comprised of
a strengthened glass having a first portion with a first surface
compressive stress and a first depth of layer of compressive stress
and a second portion with a second surface compressive stress and a
second depth of layer of compressive stress. The second glass layer
can be comprised of a strengthened glass having a third portion
with a third surface compressive stress and a third depth of layer
of compressive stress and a fourth portion with a fourth surface
compressive stress and a fourth depth of layer of compressive
stress.
[0015] It is to be understood that both the foregoing general
description and the following detailed description present
embodiments of the present disclosure, 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 present
disclosure, and are incorporated into and constitute a part of this
specification. The drawings illustrate various embodiments and
together with the description serve to explain the principles and
operations of the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] For the purposes of illustration, there are forms shown in
the drawings that are presently preferred, it being understood,
however, that the embodiments disclosed and discussed herein are
not limited to the precise arrangements and instrumentalities
shown.
[0017] FIG. 1 is a flow diagram illustrating some embodiments of
the present disclosure.
[0018] FIG. 2 is a flow diagram illustrating additional embodiments
of the present disclosure.
[0019] FIG. 3 is a cross sectional illustration of some embodiments
of the present disclosure.
[0020] FIG. 4 is a perspective view of additional embodiments of
the present disclosure.
[0021] FIG. 5 is another perspective view of FIGS. 3 and 4 showing
regions where reduced and full strength are desired.
[0022] FIG. 6 is a perspective view of a glass article with an
array of localized annealed portions.
DETAILED DESCRIPTION
[0023] In the following description, like reference characters
designate like or corresponding parts throughout the several views
shown in the figures. It is also understood that, unless otherwise
specified, terms such as "top," "bottom," "outward," "inward," and
the like are words of convenience and are not to be construed as
limiting terms. In addition, whenever a group is described as
comprising at least one of a group of elements and combinations
thereof, it is understood that the group may comprise, consist
essentially of, or consist of any number of those elements recited,
either individually or in combination with each other.
[0024] Similarly, whenever a group is described as consisting of at
least one of a group of elements or combinations thereof, it is
understood that the group may consist of any number of those
elements recited, either individually or in combination with each
other. Unless otherwise specified, a range of values, when recited,
includes both the upper and lower limits of the range. As used
herein, the indefinite articles "a," and "an," and the
corresponding definite article "the" mean "at least one" or "one or
more," unless otherwise specified
[0025] The following description of the present disclosure is
provided as an enabling teaching thereof and its best,
currently-known embodiment. Those skilled in the art will recognize
that many changes can be made to the embodiment described herein
while still obtaining the beneficial results of the present
disclosure. It will also be apparent that some of the desired
benefits of the present disclosure can be obtained by selecting
some of the features of the present disclosure without utilizing
other features. Accordingly, those of ordinary skill in the art
will recognize that many modifications and adaptations of the
present disclosure are possible and can even be desirable in
certain circumstances and are part of the present disclosure. Thus,
the following description is provided as illustrative of the
principles of the present disclosure and not in limitation
thereof.
[0026] Those skilled in the art will appreciate that many
modifications to the exemplary embodiments described herein are
possible without departing from the spirit and scope of the present
disclosure. Thus, the description is not intended and should not be
construed to be limited to the examples given but should be granted
the full breadth of protection afforded by the appended claims and
equivalents thereto. In addition, it is possible to use some of the
features of the present disclosure without the corresponding use of
other features. Accordingly, the foregoing description of exemplary
or illustrative embodiments is provided for the purpose of
illustrating the principles of the present disclosure and not in
limitation thereof and can include modification thereto and
permutations thereof.
[0027] FIG. 1 is a flow diagram illustrating some embodiments of
the present disclosure. With reference to FIG. 1, some embodiments
include the application of one or more processes for producing a
relatively thin glass sheet (on the order of about 2 mm or less)
having certain characteristics, such as relatively moderate
compressive stress (CS), relatively high depth of compressive layer
(DOL), and/or moderate central tension (CT). The process includes
preparing a glass sheet capable of ion exchange (step 100). The
glass sheet can then be subjected to an ion exchange process (step
102), and thereafter the glass sheet can be subjected to an anneal
process (step 104).
[0028] The ion exchange process 102 can involve subjecting the
glass sheet to a molten salt bath including KNO.sub.3, preferably
relatively pure KNO.sub.3 for one or more first temperatures within
the range of about 400-500.degree. C. and/or for a first time
period within the range of about 1-24 hours, such as, but not
limited to, about 8 hours. It is noted that other salt bath
compositions are possible and would be within the skill level of an
artisan to consider such alternatives. Thus, the disclosure of
KNO.sub.3 should not limit the scope of the claims appended
herewith. Such an exemplary ion exchange process can produce an
initial compressive stress (iCS) at the surface of the glass sheet,
an initial depth of compressive layer (iDOL) into the glass sheet,
and an initial central tension (iCT) within the glass sheet.
[0029] In general, after an exemplary ion exchange process, the
initial compressive stress (iCS) can exceed a predetermined (or
desired) value, such as being at or greater than about 500 MPa, and
can typically reach 600 MPa or higher, or even reach 1000 MPa or
higher in some glasses and under some processing profiles.
Alternatively, after an exemplary ion exchange process, initial
depth of compressive layer (iDOL) can be below a predetermined (or
desired) value, such as being at or less than about 75 .mu.m or
even lower in some glasses and under some processing profiles.
Alternatively, after an exemplary ion exchange process, initial
central tension (iCT) can exceed a predetermined (or desired)
value, such as above a predetermined frangibility limit of the
glass sheet, which can be at or above about 40 MPa, or more
particularly at or above about 48 MPa in some glasses.
[0030] If the initial compressive stress (iCS) exceeds a desired
value, initial depth of compressive layer (iDOL) is below a desired
value, and/or initial central tension (iCT) exceeds a desired
value, this can lead to undesirable characteristics in a final
product made using the respective glass sheet. For example, if the
initial compressive stress (iCS) exceeds a desired value (reaching
for example, 1000 MPa), then facture of the glass under certain
circumstances might not occur. Although this may be
counter-intuitive, in some circumstances the glass sheet should be
able to break, such as in an automotive glass application where the
glass must break at a certain impact load to prevent injury.
[0031] Further, if the initial depth of compressive layer (iDOL) is
below a desired value, then under certain circumstances the glass
sheet can break unexpectedly and under undesirable circumstances.
Typical ion exchange processes can result in an initial depth of
compressive layer (iDOL) being no more than about 40-60 .mu.m,
which can be less than the depth of scratches, pits, etc.,
developed in the glass sheet during use. For example, it has been
discovered that installed automotive glazing (using ion exchanged
glass) can develop external scratches reaching as deep as about 75
.mu.m or more due to exposure to abrasive materials such as silica
sand, flying debris, etc., within the environment in which the
glass sheet is used. This depth can exceed the typical depth of
compressive layer, which can lead to the glass unexpectedly
fracturing during use.
[0032] Finally, if the initial central tension (iCT) exceeds a
desired value, such as reaching or exceeding a chosen frangibility
limit of the glass, then the glass sheet can break unexpectedly and
under undesirable circumstances. For example, it has been
discovered that a 4 inch.times.4 inch.times.0.7 mm sheet of Corning
Gorilla.RTM. Glass exhibits performance characteristics in which
undesirable fragmentation (energetic failure into a large number of
small pieces when broken) occurs when a long single step ion
exchange process (8 hours at 475.degree. C.) was performed in pure
KNO.sub.3. Although a DOL of about 101 .mu.m was achieved, a
relatively high CT of 65 MPa resulted, which was higher than the
chosen frangibility limit (48 MPa) of the subject glass sheet.
[0033] In accordance with one or more embodiments, however, after
the glass sheet has been subject to ion exchange, the glass sheet
can be subjected to an annealing process 104 by elevating the glass
sheet to one or more second temperatures for a second period of
time. For example, the annealing process 104 can be carried out in
an air environment, can be performed at second temperatures within
the range of about 400-500.degree. C., and can be performed in a
second time period within the range of about 4-24 hours, such as,
but not limited to, about 8 hours. The annealing process 104 can
thus cause at least one of the initial compressive stress (iCS),
the initial depth of compressive layer (iDOL), and the initial
central tension (iCT) to be modified.
[0034] For example, after the annealing process 104, the initial
compressive stress (iCS) can be reduced to a final compressive
stress (fCS) which is at or below a predetermined value. By way of
example, the initial compressive stress (iCS) can be at or greater
than about 500 MPa, but the final compressive stress (fCS) can be
at or less than about 400 MPa, 350 MPa, or 300 MPa. It is noted
that the target for the final compressive stress (fCS) can be a
function of glass thickness as in thicker glass a lower fCS can be
desirable, and in thinner glass a higher fCS can be tolerable.
[0035] Additionally, after the annealing process 104, the initial
depth of compressive layer (iDOL) can be increased to a final depth
of compressive layer (IDOL) at or above the predetermined value. By
way of example, the initial depth of compressive layer (iDOL) can
be at or less than about 75 .mu.m, and the final depth of
compressive layer (fDOL) can be at or above about 80 .mu.m or 90
.mu.m, such as 100 .mu.m or more.
[0036] Alternatively, after the annealing process 104, the initial
central tension (iCT) can be reduced to a final central tension
(fCT) at or below the predetermined value. By way of example, the
initial central tension (iCT) can be at or above a chosen
frangibility limit of the glass sheet (such as between about 40-48
MPa), and the final central tension (fCT) can be below the chosen
frangibility limit of the glass sheet. Additional examples for
generating exemplary ion exchangeable glass structures are
described in co-pending U.S. application Ser. No. 13/626,958, filed
Sep. 26, 2012 and U.S. application Ser. No. 13/926,461, filed Jun.
25, 2013 the entirety of each being incorporated herein by
reference.
[0037] As noted above the conditions of the ion exchange step and
the annealing step can be adjusted to achieve a desired compressive
stress at the glass surface (CS), depth of compressive layer (DOL),
and central tension (CT). The ion exchange step can be carried out
by immersion of the glass sheet into a molten salt bath for a
predetermined period of time, where ions within the glass sheet at
or near the surface thereof are exchanged for larger metal ions,
for example, from the salt bath. By way of example, the molten salt
bath can include KNO.sub.3, the temperature of the molten salt bath
can be within the range of about 400-500.degree. C., and the
predetermined time period can be within the range of about 1-24
hours, and preferably between about 2-8 hours. The incorporation of
the larger ions into the glass strengthens the sheet by creating a
compressive stress in a near surface region. A corresponding
tensile stress can be induced within a central region of the glass
sheet to balance the compressive stress.
[0038] By way of further example, sodium ions within the glass
sheet can be replaced by potassium ions from the molten salt bath,
though other alkali metal ions having a larger atomic radius, such
as rubidium or cesium, can also replace smaller alkali metal ions
in the glass. According to some embodiments, smaller alkali metal
ions in the glass sheet can be replaced by Ag+ ions. Similarly,
other alkali metal salts such as, but not limited to, sulfates,
halides, and the like can be used in the ion exchange process.
[0039] The replacement of smaller ions by larger ions at a
temperature below that at which the glass network can relax
produces a distribution of ions across the surface of the glass
sheet resulting in a stress profile. The larger volume of the
incoming ion produces a compressive stress (CS) on the surface and
tension (central tension, or CT) in the center region of the glass.
The compressive stress is related to the central tension by the
following approximate relationship:
C S = C T ( t - 2 D O L D O L ) ##EQU00001##
where t represents the total thickness of the glass sheet and DOL
represents the depth of exchange, also referred to as depth of
compressive layer.
[0040] Any number of specific glass compositions can be employed in
producing the glass sheet. For example, ion-exchangeable glasses
suitable for use in the embodiments herein include alkali
aluminosilicate glasses or alkali aluminoborosilicate glasses,
though other glass compositions are contemplated. As used herein,
"ion exchangeable" means that a glass is capable of exchanging
cations located at or near the surface of the glass with cations of
the same valence that are either larger or smaller in size.
[0041] For example, a suitable glass composition comprises
SiO.sub.2, B.sub.2O.sub.3 and Na.sub.2O, where
(SiO.sub.2+B.sub.2O.sub.3).gtoreq.66 mol. %, and Na.sub.2O.gtoreq.9
mol. %. In an embodiment, the glass sheets include at least 6 wt. %
aluminum oxide. In a further embodiment, a glass sheet includes one
or more alkaline earth oxides, such that a content of alkaline
earth oxides is at least 5 wt. %. Suitable glass compositions, in
some embodiments, further comprise at least one of K.sub.2O, MgO,
and CaO. In a particular embodiment, the glass can comprise 61-75
mol. % SiO.sub.2; 7-15 mol. % Al.sub.2O.sub.3; 0-12 mol. %
B.sub.2O.sub.3; 9-21 mol. % Na.sub.2O; 0-4 mol. % K.sub.2O; 0-7
mol. % MgO; and 0-3 mol. % CaO.
[0042] A further example glass composition suitable for forming
hybrid glass laminates comprises: 60-70 mol. % SiO.sub.2; 6-14 mol.
% Al.sub.2O.sub.3; 0-15 mol. % B.sub.2O.sub.3; 0-15 mol. %
Li.sub.2O; 0-20 mol. % Na.sub.2O; 0-10 mol. % K.sub.2O; 0-8 mol. %
MgO; 0-10 mol. % CaO; 0-5 mol. % ZrO.sub.2; 0-1 mol. % SnO.sub.2;
0-1 mol. % CeO.sub.2; less than 50 ppm As.sub.2O.sub.3; and less
than 50 ppm Sb.sub.2O.sub.3; where 12 mol.
%.ltoreq.(Li.sub.2O+Na.sub.2O+K.sub.2O).ltoreq.20 mol. % and 0 mol.
%.ltoreq.(MgO+CaO).ltoreq.10 mol. %.
[0043] A still further example glass composition comprises:
63.5-66.5 mol. % SiO.sub.2; 8-12 mol. % Al.sub.2O.sub.3; 0-3 mol. %
B.sub.2O.sub.3; 0-5 mol. % Li.sub.2O; 8-18 mol. % Na.sub.2O; 0-5
mol. % K.sub.2O; 1-7 mol. % MgO; 0-2.5 mol. % CaO; 0-3 mol. %
ZrO.sub.2; 0.05-0.25 mol. % SnO.sub.2; 0.05-0.5 mol. % CeO.sub.2;
less than 50 ppm As.sub.2O.sub.3; and less than 50 ppm
Sb.sub.2O.sub.3; where 14 mol.
%.ltoreq.(Li.sub.2O+Na.sub.2O+K2O).ltoreq.18 mol. % and 2 mol.
%.ltoreq.(MgO+CaO).ltoreq.7 mol. %.
[0044] In another embodiment, an alkali aluminosilicate glass
comprises, consists essentially of, or consists of: 61-75 mol. %
SiO.sub.2; 7-15 mol. % Al.sub.2O.sub.3; 0-12 mol. % B.sub.2O.sub.3;
9-21 mol. % Na.sub.2O; 0-4 mol. % K.sub.2O; 0-7 mol. % MgO; and 0-3
mol. % CaO.
[0045] In a particular embodiment, an alkali aluminosilicate glass
comprises alumina, at least one alkali metal and, in some
embodiments, greater than 50 mol. % SiO.sub.2, in other embodiments
at least 58 mol. % SiO.sub.2, and in still other embodiments at
least 60 mol. % SiO.sub.2, wherein the ratio
Al 2 O 3 + B 2 O 3 modifiers > 1 , ##EQU00002##
where in the ratio the components are expressed in mol. % and the
modifiers are alkali metal oxides. This glass, in particular
embodiments, comprises, consists essentially of, or consists of:
58-72 mol. % SiO.sub.2; 9-17 mol. % Al.sub.2O.sub.3; 2-12 mol. %
B.sub.2O.sub.3; 8-16 mol. % Na.sub.2O; and 0-4 mol. % K.sub.2O,
wherein the ratio
Al 2 O 3 + B 2 O 3 modifiers > 1. ##EQU00003##
[0046] In yet another embodiment, an alkali aluminosilicate glass
substrate comprises, consists essentially of, or consists of: 60-70
mol. % SiO.sub.2; 6-14 mol. % Al.sub.2O.sub.3; 0-15 mol. %
B.sub.2O.sub.3; 0-15 mol. % Li.sub.2O; 0-20 mol. % Na.sub.2O; 0-10
mol. % K.sub.2O; 0-8 mol. % MgO; 0-10 mol. % CaO; 0-5 mol. %
ZrO.sub.2; 0-1 mol. % SnO.sub.2; 0-1 mol. % CeO.sub.2; less than 50
ppm As.sub.2O.sub.3; and less than 50 ppm Sb.sub.2O.sub.3; wherein
12 mol. %.ltoreq.Li.sub.2O+Na.sub.2O+K.sub.2O.ltoreq.20 mol. % and
0 mol. %.ltoreq.MgO+CaO.ltoreq.10 mol. %.
[0047] In still another embodiment, an alkali aluminosilicate glass
comprises, consists essentially of, or consists of: 64-68 mol. %
SiO.sub.2; 12-16 mol. % Na.sub.2O; 8-12 mol. % Al.sub.2O.sub.3; 0-3
mol. % B.sub.2O.sub.3; 2-5 mol. % K.sub.2O; 4-6 mol. % MgO; and 0-5
mol. % CaO, wherein: 66 mol.
%.ltoreq.SiO.sub.2+B.sub.2O.sub.3+CaO.ltoreq.69 mol. %;
Na.sub.2O+K.sub.2O+B.sub.2O.sub.3+MgO+CaO+SrO.gtoreq.10 mol. %; 5
mol. %.ltoreq.MgO+CaO+SrO.ltoreq.8 mol. %;
(Na.sub.2O+B.sub.2O.sub.3).ltoreq.Al.sub.2O.sub.3.ltoreq.2 mol. %;
2 mol. %.ltoreq.Na.sub.2O.ltoreq.Al.sub.2O.sub.3.ltoreq.6 mol. %;
and 4 mol.
%.ltoreq.(Na.sub.2O+K.sub.2O).ltoreq.Al.sub.2O.sub.3.ltoreq.10 mol.
%. Additional compositions of exemplary glass structures are
described in co-pending U.S. application Ser. No. 13/626,958, filed
Sep. 26, 2012 and U.S. application Ser. No. 13/926,461, filed Jun.
25, 2013 the entirety of each being incorporated herein by
reference.
[0048] FIG. 2 is a flow diagram illustrating additional embodiments
of the present disclosure. With reference to FIG. 2, these
embodiments can include in step 200 providing an article of glass
that has been chemically strengthened as discussed above. The
article can then be brought to another work station or kept at the
same work status whereby a suitable laser or other system (e.g.,
microwave, induction, or the like) can be targeted onto
predetermined locations of the article by moving the laser or using
a lens-array to change the target from one location to the next at
step 202. An exemplary laser can thus impart energy to the target
on the article, heating the glass and causing the compressive
stress to be reduced by an annealing action in the target area. In
some embodiments, settings of the laser and the respective exposure
time can be adjusted to cause a full or partial annealing effect in
the target area. Once the desired effect is achieved in one target
location, the laser can be re-targeted to a new location at step
204 and the process repeated to achieve a patterning of the glass
article. While one laser has been described herein, the claims
appended herewith should not be so limited as an array of lasers
can be employed that are individually or independently controlled
to produce a desired annealed pattern or provide annealing in a
predetermined area on the article.
[0049] Suitable lasers for embodiments of the present disclosure
include, but are not limited to, a CO.sub.2 laser system, an Nd:YAG
system, etc. Such lasers possess an advantage that laser energy
from the respective CO.sub.2 laser can be strongly absorbed by the
glass so that the energy of the laser can be concentrated within
the surface layer of the glass, i.e., the location where the
compressive stresses of tempered glasses are localized. A CO.sub.2
laser can typically penetrate about 10 or more microns into an
exemplary glass surface; however, the power thereof can be
controlled to achieve a desired depth of anneal in some embodiments
of the present disclosure. Such embodiments can provide a surface
specific absorption of laser energy whereby annealing can be
localized to areas on only one surface of the exemplary tempered
glass article, leaving the opposing tempered surface
non-annealed.
[0050] In another embodiment of the present disclosure, localized
annealing can be achieved on both sides of a glass article or
laminate structure to achieve a desired and/or localized annealing
on multiple tempered surfaces of the article. Exemplary laser
technology or equipment can be employed to achieve such localized
annealing by, for example, controlling the energy density, the
dwell time, and/or the rate of heating of the glass by the laser to
avoid inducing damage to the glass surface or portions thereof. In
additional embodiments, the spot size of the laser can be adjusted
to manage the energy density as well as optimize the amount of
glass area being affected (i.e., to minimize the process cycle
time). Embodiments of the present disclosure envision a large
variety of annealing patterns. For example, some embodiments can
employ laser technology to anneal a glass product in a grid pattern
of dots or points whereby the points are about 1 cm.sup.2 in area
with distance between adjacent points being approximately about 1
cm. This grid pattern would be effective in meeting safety
requirements for head impact while still retaining a significant
amount of the original un-annealed strength of the glass in the
area of the laser pattern.
[0051] While embodiments of the present disclosure have been
described with regard to laser technology, the claims appended
herewith should not be so limited as alternative processes can be
utilized to create a pattern of annealed glass. For example,
microwave systems can be employed in alternative embodiments of the
present disclosure to enable selective heating of glass. Patterned
annealing of a glass article with a microwave system, e.g.,
microwave energy, can be achieved using shielding material having a
designed pattern of holes or the like which is placed between the
article and the microwave energy source. In another embodiment,
induction heating can be employed for localized annealing of a
glass article. Patterned annealing of the article with an induction
heating system can be achieved using a printed design pattern
(placed or printed) on the glass article surface. This printed
design pattern can thus preferentially absorb or block energy from
an induction source thereby resulting in the glass article being
locally annealed in the desired locations.
[0052] Different combinations of time and temperature can be
employed in embodiments of the present disclosure to achieve a
localized reduction of stress (i.e., annealing) of 50 MPa or more
for chemically-tempered Gorilla.RTM. Glass as shown in Table 1
below.
TABLE-US-00001 TABLE 1 Time required for a stress reduction of 50
MPa Temperature (Celsius) (min) 250 960 300 150 325 60 350 30 375
15 400 7.5 425 2.5
[0053] It should be noted that the values in Table 1 are exemplary
only and should not limit the scope of the claims appended herewith
as higher and varying temperatures and/or times are also
envisioned. Further, if localized heating of greater than
425.degree. C. is achieved by the laser energy source, then the
time required to anneal each target can be much shorter. The
processes described herein can be suitable for a range of
applications. One application of particular interest is for
automotive glazing applications, whereby the process enables
production of glass which can pass automotive impact safety
standards. Other applications can be identified by those
knowledgeable in the art.
[0054] FIG. 3 is a cross sectional illustration of some embodiments
of the present disclosure. FIG. 4 is a perspective view of
additional embodiments of the present disclosure. With reference to
FIGS. 3 and 4, an exemplary embodiment can include two layers of
chemically strengthened glass, e.g., Gorilla.RTM. Glass, that have
been heat treated, ion exchanged and annealed, as described above.
Exemplary embodiments can possess a surface compression or
compressive stress of approximately 300 MPa and a DOL of greater
than about 60 microns. In a preferred embodiment, a laminate 10 can
be comprised of an outer layer 12 of glass having a thickness of
less than or equal to 10 mm and having a residual surface CS level
of between about 250 MPa to about 350 MPa with a DOL of greater
than 60 microns. In another embodiment the CS level of the outer
layer 12 is preferably about 300 MPa. The laminate 10 also includes
a polymeric interlayer 14 and an inner layer of glass 16 also
having a thickness of less than or equal to 1.0 mm and having a
residual surface CS level of between about 250 MPa to about 350 MPa
with a DOL of greater than 60 microns. In another embodiment the CS
level of the inner layer 16 is preferably about 300 MPa. In one
embodiment, an interlayer 14 can have a thickness of approximately
0.8 mm Exemplary interlayers 14 can include, but are not limited to
poly-vinyl-butyral or other suitable polymeric materials. In
additional embodiments, any of the surfaces of the outer and/or
inner layers 12, 16 can be acid etched to improve durability to
external impact events. For example, in one embodiment, a first
surface 13 of the outer layer 12 is acid etched and/or another
surface 17 of the inner layer is acid etched. In another
embodiment, a first surface 15 of the outer layer is acid etched
and/or another surface 19 of the inner layer is acid etched. Such
embodiments can thus provide a laminate construction that is
substantially lighter than conventional laminate structures and
which conforms to regulatory impact requirements.
[0055] In another embodiment of the present disclosure, at least
one layer of thin but high strength glass can be used to construct
an exemplary laminate structure. In such an embodiment, chemically
strengthened glass, e.g., Gorilla.RTM. Glass can be used for the
outer layer 12 and/or inner layer 16 of glass for an exemplary
laminate 10. In another embodiment, the inner layer 16 of glass can
be conventional soda lime glass, annealed glass, or the like.
Exemplary thicknesses of the outer and/or inner layers 12, 16 can
range in thicknesses from 0.55 mm to 1.5 mm to 2.0 mm or more.
Additionally, the thicknesses of the outer and inner layers 12, 16
can be different in a laminate structure 10. Exemplary glass layers
can be made by fusion drawing, as described in U.S. Pat. Nos.
7,666,511, 4,483,700 and 5,674,790, the entirety of each being
incorporated herein by reference, and then chemically strengthening
such drawn glass. Exemplary glass layers 12, 16 can thus possess a
deep DOL of CS and can present a high flexural strength, scratch
resistance and impact resistance. Exemplary embodiments can also
include acid etched or flared surfaces to increase the impact
resistance and increasing the strength of such surfaces by reducing
the size and severity of flaws on these surfaces. If etched
immediately prior to lamination, the strengthening benefit of
etching or flaring can be maintained on surfaces bonded to the
inter-layer.
[0056] One embodiment of the present disclosure is directed to a
laminate structure having a first glass layer, a second glass
layer, and at least one polymer interlayer intermediate the first
and second glass layers. The first glass layer can be comprised of
a thin, chemically strengthened glass having a surface compressive
stress of between about 250 MPa and about 350 MPa and a depth of
layer (DOL) of CS greater than about 60 .mu.m. In another
embodiment, the second glass layer can be comprised of a thin,
chemically strengthened glass having a surface compressive stress
of between about 250 MPa and about 350 MPa and a depth of layer
(DOL) of CS greater than about 60 .mu.m. Preferable surface
compressive stresses of the first and/or second glass layers can be
approximately 300 MPa. In some embodiments, the thicknesses of the
first and/or second glass layers can be a thickness not exceeding
1.5 mm, a thickness not exceeding 1.0 mm, a thickness not exceeding
0.7 mm, a thickness not exceeding 0.5 mm, a thickness within a
range from about 0.5 mm to about 1.0 mm, a thickness from about 0.5
mm to about 0.7 mm. Of course, the thicknesses and/or compositions
of the first and second glass layers can be different from each
other. Additionally, the surface of the first glass layer opposite
the interlayer can be acid etched, and the surface of the second
glass layer adjacent the interlayer can be acid etched. Exemplary
polymer interlayers include materials such as, but not limited to,
poly vinyl butyral (PVB), polycarbonate, acoustic PVB, ethylene
vinyl acetate (EVA), thermoplastic polyurethane (TPU), ionomer, a
thermoplastic material, and combinations thereof.
[0057] Another embodiment of the present disclosure is directed to
a laminate structure having a first glass layer, a second glass
layer, and at least one polymer interlayer intermediate the first
and second glass layers. The first and second glass layers can be
comprised of a thin, chemically strengthened glass having a surface
compressive stress of between about 250 MPa and about 350 MPa and a
depth of compressive layer (DOL) of greater than about 60 .mu.m.
Preferable surface compressive stresses of the first and/or second
glass layers can be approximately 300 MPa. In some embodiments, the
thicknesses of the first and/or second glass layers can be a
thickness not exceeding 1.5 mm, a thickness not exceeding 1.0 mm, a
thickness not exceeding 0.7 mm, a thickness not exceeding 0.5 mm, a
thickness within a range from about 0.5 mm to about 1.0 mm, a
thickness from about 0.5 mm to about 0.7 mm. Of course, the
thicknesses of the first and second glass layers can be different
from each other. Additionally, the surface of the first glass layer
opposite the interlayer can be acid etched, and the surface of the
second glass layer adjacent the interlayer can be acid etched. In
another embodiment, the surface of the first glass layer in contact
with the interlayer can be acid etched, and the surface of the
second glass layer opposite the interlayer can be acid etched.
Exemplary polymer interlayers include materials such as, but not
limited to, poly vinyl butyral (PVB), polycarbonate, acoustic PVB,
ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU),
ionomer, a thermoplastic material, and combinations thereof. The
first or second glass layer can have a central tension (CT) that is
below a predetermined frangibility limit.
[0058] Concerns related to damage levels of impact injuries to a
vehicle occupant has required a relatively easier breakage for
automotive glazing products. For example, in ECE R43 Revision 2,
there is a requirement that, when the laminate is impacted from an
internal object (by an occupant's head during a collision), the
laminate should fracture so as to dissipate energy during the event
and minimize risk of injury to the occupant. This requirement has
generally prevented direct use of high strength glass as both plies
of a laminate structure. It has been discovered through extensive
headform testing that exemplary laminate structures according to
embodiments of the present disclosure having one or more layers of
chemically strengthened glass with a residual surface compressive
stress level of about 250 MPa to about 350 MPa, and preferably
about 300 MPa, and with glass thicknesses of approximately 0.7 mm
for each layer, consistently comply with these test
requirements.
[0059] With continued reference to FIG. 4, another exemplary
laminate structure 10 embodiment is illustrated having an outer
layer 12 of glass with a thickness of less than or equal to 1.0 mm
and having a residual surface CS level of between about 250 MPa to
about 350 MPa with a DOL of greater than 60 microns, a polymeric
interlayer 14, and an inner layer of glass 16 also having a
thickness of less than or equal to 1.0 mm and having a residual
surface CS level of between about 250 MPa to about 350 MPa with a
DOL of greater than 60 microns. As illustrated, the laminate
structure 10 can be flat or formed to three-dimensional shapes by
bending the formed glass into a windshield or other glass structure
utilized in vehicles.
[0060] FIG. 5 is another perspective view of FIGS. 3 and 4 showing
regions where reduced and full strength are desired. FIG. 6 is a
perspective view of a glass article with an array of localized
annealed portions. With reference to FIGS. 5 and 6, a glass article
or laminate structure can be, but is not limited to, a windshield
or other suitable glass article as described above. A first area
504 of the glass article can be locally annealed to meet head form
testing or other criteria whereas a second area 502, e.g., the edge
sections of the windshield or other article, can maintain its
original strength and characteristics (see, e.g., FIGS. 3 and 4).
The first area 504 can be targeted by moving the laser or using a
lens-array to change the target from one location to a second
location. An exemplary laser can be employed to impart energy to
the target on the article, heating the glass and causing the
compressive stress to be reduced by an annealing action in the
target area. As noted above, inductive heating and/or microwave
heating mechanisms can also be employed thus the claims appended
herewith should not be limited solely to localized annealing by
laser technology. Once the desired full or partial annealing is
achieved in one target location, the laser can be re-targeted to a
new location and the process repeated to achieve a patterning 604
of the glass article. Such embodiments can provide a surface
specific absorption of laser energy whereby annealing can be
localized to predetermined areas 604 on one surface of the
exemplary glass article, leaving the other areas 602 of the glass
article (including opposing surfaces, not shown) non-locally
annealed. Of course, localized annealing can be achieved on both
sides of the glass article or laminate structure to achieve a
desired and/or localized annealing on multiple tempered surfaces of
the article to thereby achieve a plurality of differing surface
compressive stresses and depth of layers of compressive stress in a
single glass article. Furthermore, it is envisioned that the level
of annealing imparted by a respective laser(s) (or microwave or
induction source) can be modified from successive points or spots
in the first area 504 to create plural points or spots, or sets
thereof, having different levels of annealing in the first area 504
(and hence differing levels of surface compressive stress and depth
of layer of compressive stress between spots or points in the first
area 504).
[0061] Exemplary laser technology or equipment can be employed to
achieve such localized annealing by, for example, controlling the
energy density, the dwell time, and/or the rate of heating of the
glass by the laser to avoid inducing damage to the glass surface or
portions thereof. In additional embodiments, the spot size of the
laser can be adjusted to manage the energy density as well as
optimize the amount of glass area being affected (i.e., to minimize
the process cycle time). Embodiments of the present disclosure
envision a large variety of annealing patterns thus the depicted
array of points or dots in FIG. 6 should not limit the scope of the
claims appended herewith. For example, some embodiments can employ
laser, microwave or inductive technology to anneal a glass product
in a pattern of rows, ovals, points or other geometric figures or
arrays with varying distance between individual targeted areas.
Regardless, the grid pattern formed by such geometries should be
effective in meeting safety requirements for head impact while
retaining a significant amount of the original un-annealed strength
of the glass in the area of the laser pattern.
[0062] Embodiments of the present disclosure provide an ability to
reduce the strength of the glass in specific areas of a glass
article, to make the article compliant with safety standards (such
as head impact) while maintaining the full strength of the glass in
other areas of the article (e.g., near the edges of the article).
In non-limiting embodiments employing lasers, the laser equipment
can be programmed to expose certain areas and not expose other
areas, thereby eliminating the need for additional tooling to cause
the pattern of annealed glass. In these embodiments, the amount of
annealing can be readily adjusted by changing the laser parameters,
such as increasing or decreasing the power of the laser. By
creating a pattern of annealed glass, instead of annealing a large
continuous area of glass, glass articles according to embodiments
of the present disclosure can retain more of its original strength
while the locally annealed regions can be a failure origin under
the stress of an impact event (such as head impact). Additional
embodiments also provide the advantage of localized annealing on
one or both surfaces of a glass article.
[0063] Some embodiments of the present disclosure provide a method
of providing locally annealed regions for a glass article. The
method includes providing a strengthened glass article having a
first surface compressive stress and a first depth of layer of
compressive stress and targeting first portions of the glass
article on a first side thereof. The method also includes annealing
the targeted first portions to a second surface compressive stress
and a second depth of layer of compressive stress and repeating
steps the targeting and annealing to create a pattern of annealed
portions of the glass article on the first side thereof. In
additional embodiments, the second surface compressive stress and
the second depth of layer of compressive stress are less than the
first surface compressive stress and the first depth of layer of
compressive stress, respectively. The step of annealing can further
comprise focusing a laser on the targeted first portions for a
predetermined energy density and dwell time to avoid inducing
damage to the glass article. Exemplary lasers include, but are not
limited to, a CO.sub.2 laser or an Nd:YAG laser. Of course, other
methods of localized annealed can be employed such as, but not
limited to, selectively heating the targeted first portions using
microwave energy or selectively heating the targeted first portions
using an induction source. Any one of these other methods can also
employ shielding non-targeted portions of the glass article with
shielding material or preferentially absorbing or blocking energy
from the induction source, as applicable. In other embodiments, the
method includes targeting third portions of the glass article on a
second side thereof, annealing the targeted third portions to a
third surface compressive stress and a third depth of layer of
compressive stress, and repeating these additional targeting and
annealing steps to create a pattern of annealed portions of the
glass article on the second side thereof. In some embodiments, the
second surface compressive stress and the third surface compressive
stress are different. In other embodiments, the second depth of
layer of compressive stress and the third depth of layer of
compressive stress are different. An exemplary strengthened glass
article can include one or more glass layers and an interlayer.
Additionally, an exemplary strengthened glass article can include a
chemically strengthened glass layer, a thermally strengthened glass
layer, or a combination thereof.
[0064] Additional embodiments of the present disclosure provide a
laminate structure having a first glass layer, a second glass
layer, and at least one polymer interlayer intermediate the first
and second glass layers. The first glass layer can be comprised of
a strengthened glass having a first portion with a first surface
compressive stress and a first depth of layer of compressive stress
and a second portion with a second surface compressive stress and a
second depth of layer of compressive stress. The strengthened glass
of the first layer and/or second layer can be chemically
strengthened glass or thermally strengthened glass. In one
embodiment, the first surface compressive stress can be between
about 250 MPa and about 350 MPa and the first depth of layer of
compressive stress can be greater than about 60 .mu.m. In another
embodiment, the second surface compressive stress can be less than
the first surface compressive stress and the second depth of layer
of compressive stress can be less than the first depth of layer of
compressive stress. In some embodiments, the second glass layer can
be comprised of a strengthened glass having a third portion with a
third surface compressive stress and a third depth of layer of
compressive stress and a fourth portion with a fourth surface
compressive stress and a fourth depth of layer of compressive
stress. In another embodiment, the third surface compressive stress
can be between about 250 MPa and about 350 MPa and the third depth
of layer of compressive stress can be greater than about 60 .mu.m.
In additional embodiments, the fourth surface compressive stress
can be less than the third surface compressive stress and the
fourth depth of layer of compressive stress can be less than the
third depth of layer of compressive stress. Of course, the first
and third surface compressive stresses can be different, and the
first and third depth of layer of compressive stresses can be
different. Exemplary thicknesses of the first and second glass
layers can be, but are not limited to, a thickness not exceeding
1.5 mm, a thickness not exceeding 1.0 mm, a thickness not exceeding
0.7 mm, a thickness not exceeding 0.5 mm, a thickness within a
range from about 0.5 mm to about 1.0 mm, a thickness from about 0.5
mm to about 0.7 mm. In some embodiments, the thicknesses and/or
compositions of the first and second glass layers can be different.
An exemplary polymer interlayer can be, but is not limited to, poly
vinyl butyral (PVB), polycarbonate, acoustic PVB, ethylene vinyl
acetate (EVA), thermoplastic polyurethane (TPU), ionomer, a
thermoplastic material, and combinations thereof. An exemplary,
non-limiting thickness for an interlayer can be approximately 0.8
mm.
[0065] Further embodiments of the present disclosure provide a
laminate structure having a first glass layer, a second glass
layer, and at least one polymer interlayer intermediate the first
and second glass layers. The first glass layer can be comprised of
a strengthened glass having a first portion with a first surface
compressive stress and a first depth of layer of compressive stress
and a second portion with a second surface compressive stress and a
second depth of layer of compressive stress. The second glass layer
can be comprised of a strengthened glass having a third portion
with a third surface compressive stress and a third depth of layer
of compressive stress and a fourth portion with a fourth surface
compressive stress and a fourth depth of layer of compressive
stress. The strengthened glass of the first layer and/or second
layer can be chemically strengthened glass or thermally
strengthened glass. In one embodiment, the first surface
compressive stress can be between about 250 MPa and about 350 MPa
and the first depth of layer of compressive stress can be greater
than about 60 .mu.m. In another embodiment, the second surface
compressive stress can be less than the first surface compressive
stress and the second depth of layer of compressive stress can be
less than the first depth of layer of compressive stress. In
another embodiment, the third surface compressive stress can be
between about 250 MPa and about 350 MPa and the third depth of
layer of compressive stress can be greater than about 60 .mu.m. In
additional embodiments, the fourth surface compressive stress can
be less than the third surface compressive stress and the fourth
depth of layer of compressive stress can be less than the third
depth of layer of compressive stress. Of course, the first and
third surface compressive stresses can be different, and the first
and third depth of layer of compressive stresses can be different.
Exemplary thicknesses of the first and second glass layers can be,
but are not limited to, a thickness not exceeding 1.5 mm, a
thickness not exceeding 1.0 mm, a thickness not exceeding 0.7 mm, a
thickness not exceeding 0.5 mm, a thickness within a range from
about 0.5 mm to about 1.0 mm, a thickness from about 0.5 mm to
about 0.7 mm. In some embodiments, the thicknesses and/or
compositions of the first and second glass layers can be different.
An exemplary polymer interlayer can be, but is not limited to, poly
vinyl butyral (PVB), polycarbonate, acoustic PVB, ethylene vinyl
acetate (EVA), thermoplastic polyurethane (TPU), ionomer, a
thermoplastic material, and combinations thereof. An exemplary,
non-limiting thickness for an interlayer can be approximately 0.8
mm.
[0066] While this description can include many specifics, these
should not be construed as limitations on the scope thereof, but
rather as descriptions of features that can be specific to
particular embodiments. Certain features that have been heretofore
described in the context of separate embodiments can also be
implemented in combination in a single embodiment. Conversely,
various features that are described in the context of a single
embodiment can also be implemented in multiple embodiments
separately or in any suitable subcombination. Moreover, although
features can be described above as acting in certain combinations
and can even be initially claimed as such, one or more features
from a claimed combination can in some cases be excised from the
combination, and the claimed combination can be directed to a
subcombination or variation of a subcombination.
[0067] Similarly, while operations are depicted in the drawings or
figures in a particular order, this should not be understood as
requiring that such operations be performed in the particular order
shown or in sequential order, or that all illustrated operations be
performed, to achieve desirable results. In certain circumstances,
multitasking and parallel processing can be advantageous.
[0068] As shown by the various configurations and embodiments
illustrated in FIGS. 1-6, various embodiments for methods for
localized annealing of chemically strengthened glass have been
described.
[0069] While preferred embodiments of the present disclosure have
been described, it is to be understood that the embodiments
described are illustrative only and that the scope of the invention
is to be defined solely by the appended claims when accorded a full
range of equivalence, many variations and modifications naturally
occurring to those of skill in the art from a perusal hereof
* * * * *