U.S. patent application number 12/012891 was filed with the patent office on 2008-08-21 for articles such as safety laminates and solar cell modules containing high melt flow acid copolymer compositions.
Invention is credited to Matthew Scott Hall, Richard Allen Hayes, Sam Louis Samuels.
Application Number | 20080196760 12/012891 |
Document ID | / |
Family ID | 39402533 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080196760 |
Kind Code |
A1 |
Hayes; Richard Allen ; et
al. |
August 21, 2008 |
Articles such as safety laminates and solar cell modules containing
high melt flow acid copolymer compositions
Abstract
A polymeric film or sheet comprising an acid copolymer
composition comprising acid copolymer of an alpha olefin and about
1 to about 30 wt % of alpha,beta-ethylenically unsaturated
carboxylic acid having 3 to 8 carbons, based on the total weight of
the acid copolymer composition, wherein the acid copolymer has a
Melt Index of about 75 to about 600 g/10 min. The acid copolymer
composition preferably comprises an additive selected from the
group consisting of silane coupling agent, organic peroxide, and
combinations thereof. In addition, an article comprising an
interlayer formed of the polymeric film or sheet and an additional
layer selected from the group consisting of glass, other polymeric
interlayer sheets, polymeric film layers, and metal films or
sheets. Examples of articles include safety windows and solar
cells.
Inventors: |
Hayes; Richard Allen;
(Beaumont, TX) ; Samuels; Sam Louis; (Landenberg,
PA) ; Hall; Matthew Scott; (Landenberg, PA) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1122B, 4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
39402533 |
Appl. No.: |
12/012891 |
Filed: |
February 6, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60901510 |
Feb 15, 2007 |
|
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Current U.S.
Class: |
136/256 ;
156/285; 428/339; 525/221 |
Current CPC
Class: |
B32B 17/10853 20130101;
B32B 17/10018 20130101; B32B 2367/00 20130101; Y10T 428/31692
20150401; Y10T 428/269 20150115; Y10T 428/31938 20150401; C08J 5/18
20130101; B32B 17/10743 20130101; Y10T 428/31667 20150401; B32B
17/10697 20130101; B32B 27/06 20130101; B32B 27/08 20130101; B32B
17/10 20130101; B32B 17/10036 20130101; Y10T 428/31645 20150401;
B32B 27/308 20130101; C08J 2323/08 20130101; Y10T 156/1054
20150115; B32B 17/10 20130101; B32B 2367/00 20130101; B32B 17/10005
20210101; B32B 2367/00 20130101 |
Class at
Publication: |
136/256 ;
525/221; 428/339; 156/285 |
International
Class: |
H01L 31/0216 20060101
H01L031/0216; B32B 37/00 20060101 B32B037/00; B32B 17/10 20060101
B32B017/10 |
Claims
1. A polymeric film or sheet comprising an acid copolymer
composition comprising acid copolymer of an alpha olefin and about
1 to about 30 wt % of alpha,beta-ethylenically unsaturated
carboxylic acid having 3 to 8 carbons, based on the total weight of
the acid copolymer, wherein the acid copolymer has a Melt Index of
about 75 to about 600 g/10 min.
2. The polymeric film or sheet of claim 1 wherein the acid
copolymer composition further comprises an additive selected from
the group consisting of silane coupling agent, organic peroxide,
and combinations thereof.
3. An article comprising an interlayer formed of the polymeric film
or sheet of claim 1 and an additional layer selected from the group
consisting of glass, other polymeric interlayer sheets, polymeric
film layers, and metal films or sheets.
4. The article of claim 3, wherein the interlayer has a thickness
of about 0.1 to about 250 mils (about 0.003 to about 6.35 mm).
5. The article of claim 3, wherein (a) the alpha olefin is
ethylene; (b) the alpha,beta-ethylenically unsaturated carboxylic
acid is selected from the group consisting of acrylic acid,
methacrylic acid, itaconic acid, maleic acid, maleic anhydride,
fumaric acid, monomethyl maleic acid, and mixtures thereof; (c) the
acid copolymer comprises about 10 to about 25 wt % of repeat units
from the alpha,beta-ethylenically unsaturated carboxylic acid; and
(d) the acid copolymer has a Melt Index of about 100 to about 400
g/10 min.
6. The article of claim 3, wherein the acid copolymer composition
further comprises an additive selected from the group consisting of
silane coupling agent, organic peroxide, and combinations
thereof.
7. The article of claim 6, wherein (A) the acid copolymer has a
Melt Index of about 100 to about 400 g/10 min, (B) the alpha olefin
is ethylene, (C) the alpha,beta-ethylenically unsaturated
carboxylic acid is selected from the group consisting of acrylic
acid, methacrylic acid, itaconic acid, maleic acid, maleic
anhydride, fumaric acid, monomethyl maleic acid, and mixtures
thereof, and (D) the acid copolymer composition comprises about 10
to about 25 wt % of repeat units from the alpha,beta-ethylenically
unsaturated carboxylic acid, based on the total weight of the acid
copolymer composition.
8. The article of claim 6, wherein the acid copolymer composition
contains about 0.01 to about 5 wt % of the silane coupling agent,
based on the total weight of the acid copolymer composition, and
the silane coupling agent is selected from the group consisting of
gamma-chloropropylmethoxysilane, vinyltrimethoxysilane,
vinyltriethoxysilane,
vinyltris(beta-methoxyethoxy)silane,gamma-vinylbenzylpropyltrimethoxysila-
ne,
N-beta-(N-vinylbenzylaminoethyl)-gamma-aminopropyltrimethoxysilane,
gamma-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane,
gamma-glycidoxypropyltrimethoxysilane,
gamma-glycidoxypropyltriethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
vinyltrichlorosilane, gamma-mercaptopropylmethoxysilane,
gamma-aminopropyltriethoxysilane,
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and mixtures
thereof.
9. The article of claim 6, wherein the acid copolymer 20
composition contains about 0.01 to about 10 wt % of the organic
peroxide, based on the total weight of the acid copolymer
composition, and the organic peroxide is selected from the group
consisting of 2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(tert-betylperoxy)hexane-3, di-tert-butyl
peroxide, tert-butylcumyl peroxide,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide,
alpha, alpha'-bis(tert-butyl-peroxyisopropyl)benzene,
n-butyl-4,4-bis(tert-butylperoxy)valerate,
2,2-bis(tert-butylperoxy)butane,
1,1-bis(tert-butyl-peroxy)cyclohexane,
1,1-bis(tert-butylperoxy)-3,3,5-trimethyl-cyclohexane, tert-butyl
peroxybenzoate, benzoyl peroxide and mixtures thereof.
10. The article of claim 3, which is a safety glass laminate
wherein the additional layer is a glass sheet and the interlayer is
laminated to the glass sheet.
11. The article of claim 10, wherein the interlayer sheet has a
thickness of about 10 to about 250 mils (about 0.25 to about 6.35
mm).
12. The article of claim 3, which is a solar cell pre-laminate
assembly and comprises a solar cell component comprising one or a
plurality of solar cells.
13. The article of claim 12, wherein the polymeric film or sheet
has a thickness of about 0.1 to about 20 mils (about 0.003 to about
0.5 mm).
14. The article of claim 12, further comprising a second polymeric
layer that is positioned next to the solar cell component on the
opposite side from the polymeric film or sheet, wherein the second
polymeric layer comprises a polymeric composition selected from the
group consisting of poly(vinyl acetal), ethylene vinyl acetate,
polyurethane, polyvinylchloride, polyethylenes, polyolefin block
elastomers, ethylene acrylate ester copolymers, copolymer of alpha
olefin and alpha,beta-ethylenically unsaturated carboxylic acid and
ionomers thereof, silicone elastomers and epoxy resins.
15. The article of claim 12, further comprising an incident layer
that is formed of a transparent material and serves as an outer
layer at the light-receiving side of the assembly.
16. The article of claim 12, further comprising a backing layer
that is formed of glass, a plastic film or sheet, or a metal film
or sheet and serves as an outer layer at the back side of the
assembly.
17. The article of claim 12, wherein the acid copolymer has a Melt
Index of about 100 to about 400 g/10 min.
18. An article which is a solar cell module prepared by the steps
comprising (a) providing interlayer formed of the polymeric film or
sheet of claim 1, (b) providing a solar cell component comprising
one or a plurality of solar cells; and (c) encapsulating the solar
cell component in a matrix comprising the acid copolymer
composition.
19. The article of claim 18, wherein (a) the alpha olefin is
ethylene; (b) the alpha,beta-ethylenically unsaturated carboxylic
acid is selected from the group consisting of acrylic acid,
methacrylic acid, itaconic acid, maleic acid, maleic anhydride,
fumaric acid, monomethyl maleic acid, and mixtures thereof; (c) the
acid copolymer comprises about 10 to about 25 wt % of repeat units
from the alpha,beta-ethylenically unsaturated carboxylic acid; (d)
the interlayer sheet has a thickness of about 0.1 to about 20 mils
(about 0.003 to about 0.5 mm); and (e) the acid copolymer has a
Melt Index of about 100 to about 400 g/10 min.
20. A process of manufacturing an article, wherein the article is a
solar cell module, the process comprising: (i) providing a solar
cell pre-laminate assembly as described in claim 12, and (ii)
laminating the pre-laminate assembly to form the solar cell
module.
21. The process of claim 20, wherein the step (ii) of lamination is
conducted by subjecting the assembly to heat and, optionally,
vacuum.
22. A polymeric composition comprising an acid copolymer
composition and an additive, wherein (i) the acid copolymer
composition comprises an acid copolymer of an alpha olefin and
about 1 to about 30 wt % of an alpha,beta-ethylenically unsaturated
carboxylic acid having 3 to 8 carbons, based on the total weight of
the acid copolymer, (ii) the acid copolymer has a Melt Index of
about 75 to about 600 g/10 min and (iii) the additive is selected
from the group consisting of silane coupling agent, organic
peroxide and combinations thereof.
23. The polymeric composition of claim 22, wherein (A) the acid
copolymer has a Melt Index of about 100 to about 400 g/10 min, (B)
the alpha olefin is ethylene, (C) the alpha,beta-ethylenically
unsaturated carboxylic acid is selected from the group consisting
of acrylic acid, methacrylic acid, itaconic acid, maleic acid,
maleic anhydride, fumaric acid, monomethyl maleic acid, and
mixtures thereof, and (D) the acid copolymer comprises about 10 to
about 25 wt % of repeat units from the alpha,beta-ethylenically
unsaturated carboxylic acid, based on the total weight of the acid
copolymer.
24. The polymeric composition of claim 22, comprising about 0.01 to
about 5 wt % of the silane coupling agent, based on the total
weight of the polymeric composition, and wherein the silane
coupling agent is selected from the group consisting of
gamma-chloropropylmethoxysilane, vinyltrimethoxysilane,
vinyltriethoxysilane,
vinyltris(beta-methoxyethoxy)silane,gamma-vinylbenzylpropyltrimethoxysila-
ne,
N-beta-(N-vinylbenzylaminoethyl)-gamma-aminopropyltrimethoxysilane,
gamma-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane,
gamma-glycidoxypropyltrimethoxysilane,
gamma-glycidoxypropyltriethoxysilane,
beta-(3,4-epoxycyclohexylethyltrimethoxysilane,
vinyltrichlorosilane, gamma-mercaptopropylmethoxysilane,
gamma-aminopropyltriethoxysilane,
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and mixtures
thereof.
25. The polymeric composition of claim 22, comprising about 0.01 to
about 10 wt % of the organic peroxide, based on the total weight of
the polymeric composition, and wherein the organic peroxide is
selected from the group consisting of
2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(tert-betylperoxy)hexane-3, di-tert-butyl
peroxide, tert-butylcumyl peroxide,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide,
alpha, alpha'-bis(tert-butyl-peroxyisopropyl)benzene,
n-butyl-4,4-bis(tert-butylperoxy)valerate,
2,2-bis(tert-butylperoxy)butane,
1,1-bis(tert-butyl-peroxy)cyclohexane,
1,1-bis(tert-butylperoxy)-3,3,5-trimethyl-cyclohexane, tert-butyl
peroxybenzoate, benzoyl peroxide and mixtures thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Appln.
No. 60/901510, filed on Feb. 15, 2007, which is incorporated herein
by reference in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to polymeric films or sheets
comprising acid copolymer compositions, and their use in articles
such as safety laminates and solar cell modules.
BACKGROUND OF THE INVENTION
[0003] Glass laminated products have contributed to society for
almost a century. Beyond the well known, every day automotive
safety glass used in windshields, laminated glass is used in all
forms of the transportation industry. Safety glass is characterized
by high impact and penetration resistance and does not scatter
glass shards and debris when shattered.
[0004] Safety glass typically consists of a sandwich of two glass
sheets or panels bonded together with an interlayer of a polymeric
sheet. One or both of the glass sheets may be replaced with
optically clear rigid polymeric sheets, such as sheets made of
polycarbonates. Safety glass has further evolved to include
multiple layers of glass and polymeric sheets bonded together with
interlayers of polymeric sheets.
[0005] The interlayers used in safety glass are typically made from
relatively thick polymer sheets, which exhibit toughness and
bondability to the glass in the event of a crack or crash. Widely
used interlayer materials include complex, multicomponent
compositions based on poly(vinyl butyral) (PVB), poly(urethane)
(PU), poly(ethylene vinyl acetate) (EVA), acid copolymers and
ionormers derived therefrom, and the like.
[0006] As a renewable energy resource, the use of solar cell
modules is rapidly expanding. One preferred way of manufacturing a
solar cell module involves forming a pre-laminate assembly
comprising at least 5 structural layers. The solar cell
pre-laminates are constructed in the following order starting from
the top, or incident layer (that is, the layer first contacted by
light) and continuing to the backing (the layer furthest removed
from the incident layer): (1) incident layer (typically a glass
plate or a thin polymeric film (such as a fluoropolymer or
polyester film), but could conceivably be any material that is
transparent to sunlight), (2) front encapsulant layer, (3)
voltage-generating component (or solar cell component), (4) back
encapsulant layer, and (5) backing layer.
[0007] The encapsulant layers are designed to encapsulate and
protect the fragile voltage-generating component. Generally, a
solar cell pre-laminate will incorporate at least two encapsulant
layers sandwiched around the solar cell component. The optical
properties of the front encapsulant layer must be such that light
can be effectively transmitted to the solar cell component.
Additionally, encapsulant layers generally have similar
requirements and compositions to that described above for glazing
interlayers.
[0008] The use of acid copolymer compositions as solar cell
encapsulant films and sheets has been known within the art (see,
e.g., U.S. Pat. No. 3,957,537; U.S. Pat. No. 6,187,448; U.S. Pat.
No. 6,320,116; U.S. Pat. No. 6,414,236; U.S. Pat. No. 6,586,271;
U.S. Pat. No. 6,693,237; JP 2000186114; JP 2001089616; JP
2001119047; JP 2001119056; JP 2001119057; JP 2001144313; JP
2001261904; JP 2004031445; JP 2004058583; JP 2006032308; JP
2006036875; and JP 2006190867). For example, U.S. Pat. No.
6,187,448 and U.S. Pat. No. 6,320,116 disclose a multilayer solar
cell encapsulant sheet that includes an acid copolymer layer. U.S.
Pat. No. 6,414,236; U.S. Pat. No. 6,693,237 and JP 2006036875
disclose acid copolymer compositions containing organic peroxides
and silane coupling agents as solar cell encapsulant sheet
materials. JP 2000186114 discloses acid copolymer compositions,
ionomeric compositions, and blends thereof as solar cell
encapsulant sheets. JP 2001144313, JP 2004031445, JP 2004058583, JP
2006032308 and JP 2006190867 disclose acid copolymer compositions
containing silane coupling agents as solar cell encapsulant sheet
materials.
[0009] However, the acid copolymer resins being used in the art of
solar cell modules generally have a low melt flow index (MI) of 25
g/10 min or less. The use of such low melt flow acid copolymer
resins requires higher lamination temperatures (i.e., 130.degree.
C.-170.degree. C.) and therefore may complicate the lamination
process.
[0010] There is a need for polymeric film or sheet suitable for use
as interlayers in glass laminate end-use applications, such as
safety windows and solar cells, which do not have the shortcomings
described above, as well as for compositions useful in forming such
films or sheets. For instance, there is a desire to prepare useful
compositions with a reduced extrusion compounding temperature. For
instance, there is a desire to reduce the lamination temperature,
preferably to about 100.degree. C. to about 120.degree. C., or to
reduce the lamination cycle time, or both, and therefore
simplifying the lamination process. In addition, there is a desire
for films or sheets that have enhanced adhesion strength under wide
variety of lamination temperatures, including such desirable lower
temperatures, and to provide the laminates with improved shock
resistance.
SUMMARY OF THE INVENTION
[0011] The invention is directed to a polymeric film or sheet
comprising an acid copolymer composition comprising an acid
copolymer of an alpha olefin and about 1 to about 30 wt % of
alpha,beta-ethylenically unsaturated carboxylic acid having 3 to 8
carbons, based on the total weight of the acid copolymer, wherein
the acid copolymer has a Melt Index of about 75 to about 600 g/10
min.
[0012] Preferably the acid copolymer has a Melt Index of about 100
to about 400 g/10 min.
[0013] Preferably the alpha olefin is ethylene.
[0014] Preferably the alpha,beta-ethylenically unsaturated
carboxylic acid is selected from the group consisting of acrylic
acid, methacrylic acid, itaconic acid, maleic acid, maleic
anhydride, fumaric acid, monomethyl maleic acid, and mixtures
thereof.
[0015] Preferably the ionomeric copolymer comprises about 10 to
about 25 wt % (more preferably about 15 to about 23 wt %, and most
preferably about 18 to about 23 wt % ) of the
alpha,beta-ethylenically unsaturated carboxylic acid.
[0016] The films or sheets of the invention preferably have a total
thickness of about 0.1 mil (0.003 mm) to about 250 mils (6.35 mm).
In one embodiment, the polymeric film or sheet preferably has a
thickness of about 10 to about 250 mils (about 0.25 to about 6.35
mm). In another embodiment, the polymeric film or sheet preferably
has a thickness of about 0.1 to about 10 mils (about 0.003 to about
0.25 mm). In a third embodiment, the thicknesthickness is
preferably about 10 to about 20 mils (about 0.25 to about 0.51
mm).
[0017] Preferably the acid copolymer composition further comprises
an additive selected from the group consisting of silane coupling
agent, organic peroxide, and combinations thereof.
[0018] In one preferred embodiment, the acid copolymer composition
contains about 0.01 to about 5 wt % (more preferably about 0.05 to
about 1 wt %) of the silane coupling agent, based on the total
weight of the acid copolymer composition. Preferably the silane
coupling agent is selected from the group consisting of
gamma-chloropropylmethoxysilane, vinyltrimethoxysilane,
vinyltriethoxysilane,
vinyltris(beta-methoxyethoxy)silane,gamma-vinylbenzylpropyltrimethoxysila-
ne,
N-beta-(N-vinylbenzylaminoethyl)-gamma-aminopropyltrimethoxysilane,
gamma-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane,
gamma-glycidoxypropyltrimethoxysilane,
gamma-glycidoxypropyltriethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
vinyltrichlorosilane, gamma-mercaptopropylmethoxysilane,
gamma-aminopropyltriethoxysilane,
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and mixtures
thereof.
[0019] In another preferred embodiment, the acid copolymer
composition contains about 0.01 to about 10 wt % (preferably about
0.5 to about 3 wt %) of the organic peroxide, based on the total
weight of the acid copolymer composition. Preferably the organic
peroxide is selected from the group consisting of
2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(tert-betylperoxy)hexane-3, di-tert-butyl
peroxide, tert-butylcumyl peroxide,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide,
alpha, alpha'-bis(tert-butyl-peroxyisopropyl)benzene,
n-butyl-4,4-bis(tert-butylperoxy)valerate,
2,2-bis(tert-butylperoxy)butane,
1,1-bis(tert-butyl-peroxy)cyclohexane,
1,1-bis(tert-butylperoxy)-3,3,5-trimethyl-cyclohexane, tert-butyl
peroxybenzoate, benzoyl peroxide and mixtures thereof.
[0020] The invention is also directed to an article comprising an
interlayer formed of the polymeric film or sheet and an additional
layer selected from the group consisting of glass, other polymeric
interlayer sheets, polymeric film layers, and metal films or
sheets.
[0021] By "other polymeric interlayer sheets" reference is made to
an interlayer sheet that may be the same as or different than
interlayer formed of the polymeric film or sheet. Preferably the
other polymeric interlayer sheets are formed of materials selected
from the group consisting of acid copolymers and ionomers derived
therefrom, poly(ethylene-co-vinyl acetate) (EVA), poly(vinyl
acetal), polyurethane (PU), polyvinylchloride (PVC), polyethylenes,
polyolefin block elastomers, ethylene acrylate ester copolymers,
silicone elastomers and epoxy resins. In one preferred embodiment,
the other polymeric interlayer sheet is the same or substantially
similar to the interlayer formed of the polymeric film or
sheet.
[0022] Preferably the polymeric film layers are formed of materials
selected from the group consisting of polyesters, poly(ethylene
naphthalate), polycarbonate, polyolefins, norbornene polymers,
polystyrene, styrene-acrylate copolymers, acrylonitrile-styrene
copolymers, polysulfones, nylons, poly(urethanes), acrylics,
cellulose acetates, cellophane, vinyl chloride polymers, and
fluoropolymers.
[0023] In a preferred embodiment, the article is a safety glass
laminate wherein the additional layer is a glass sheet and the
interlayer is laminated to the glass sheet. Preferably the
interlayer is self-adhered to the glass sheets. Preferably the
safety glass laminate comprises two sheets of glass and the
interlayer is laminated between the glass sheets. Preferably the
interlayer is self-adhered to the two glass sheets. Preferably the
interlayer has a thickness of about 10 to about 250 mils (about
0.25 to about 6.35 mm).
[0024] In another preferred embodiment, the article is a solar cell
pre-laminate assembly and comprises a solar cell component
comprising one or a plurality of solar cells. The solar cell
pre-laminate assembly preferably further comprises a second
polymeric layer that is positioned next to the solar cell component
on the opposite side from the polymeric film or sheet, wherein the
second polymeric layer comprises a polymeric composition selected
from the group consisting of poly(vinyl acetal), ethylene vinyl
acetate, polyurethane, polyvinylchloride, polyethylenes, polyolefin
block elastomers, ethylene acrylate ester copolymers, copolymer of
alpha olefin and alpha,beta-ethylenically unsaturated carboxylic
acid and ionomers thereof, silicone elastomers and epoxy resins.
The solar cell pre-laminate assembly preferably an incident layer
that is formed of a transparent material (preferably glass or a
plastic film or sheet, most preferably glass) and serves as an
outer layer at the light-receiving side of the assembly.
[0025] The solar cell pre-laminate assembly preferably comprises a
backing layer that serves as an outer layer at the back side of the
assembly, wherein the backing layer preferably is formed of glass,
plastic films or sheets, or metal films or sheets.
[0026] In one preferred embodiment, the solar cell pre-laminate
assembly consists essentially of, from top to bottom, (i) an
incident layer formed of a transparent material, which is
positioned next to, (ii) a front encapsulant layer that is
positioned next to, (iii) a solar cell component comprising one or
a plurality of solar cells, which is positioned next to, (iv) an
optional back encapsulant layer that is positioned next to, (v) a
backing layer, wherein at least one of the encapsulant layers is
formed of the polymeric film or sheet.
[0027] The invention is further directed to an article which is a
solar cell prepared by the steps comprising (a) providing
interlayer formed of the polymeric film or sheet, (b) providing a
solar cell component comprising one or a plurality of solar cells;
and (c) encapsulating the solar cell component in a matrix
comprising the acid copolymer composition. The invention is also
directed to a process of manufacturing an article, wherein the
article is a solar cell module, the process comprising: (i)
providing a solar cell pre-laminate assembly, and (ii) laminating
the pre-laminate assembly to form the solar cell module. Preferably
the step of lamination is conducted by subjecting the assembly to
heat and, optionally, vacuum.
[0028] The invention is also directed to an improved polymeric
composition comprising an acid copolymer composition and an
additive, wherein (i) the acid copolymer composition comprises a
copolymer of an alpha olefin and about 1 to about 30 wt % of an
alpha,beta-ethylenically unsaturated carboxylic acid having 3 to 8
carbons, based on the total weight of the acid copolymer, (ii) the
acid copolymer has a Melt Index of about 75 to about 600 g/10 min
and (iii) the additive is selected from the group consisting of
silane coupling agent, organic peroxide, and combinations thereof.
The invention is also directed to shaped articles comprising this
polymeric composition. Preferably the shaped article is a polymeric
film or sheet. Preferably the film or sheet is a multilayer film or
sheet comprising one surface layer formed of the polymeric
composition. Preferably the multilayer film or sheet comprises two
surface layers with both being formed of the polymeric composition.
One preferred embodiment is a solar cell or solar cell
pre-laminate.
DETAILED DESCRIPTION OF THE INVENTION
[0029] All publications, patent applications, patents, and other
documents mentioned herein are incorporated by reference in their
entirety. Unless otherwise defined, all technical and scientific
terms used herein have the same meaning as commonly understood by
one of ordinary skill in the art to which this invention belongs.
In case of conflict, the present specification, including
definitions, will control.
[0030] Although methods and materials similar or equivalent to
those described herein can be used in the practice or testing of
the invention, suitable methods and materials are described
herein.
[0031] Unless stated otherwise, all percentages, parts, ratios,
etc., are by weight.
[0032] When an amount, concentration, or other value or parameter
is given as either a range, preferred range or a list of upper
preferable values and lower preferable values, this is to be
understood as specifically disclosing all ranges formed from any
pair of any upper range limit or preferred value and any lower
range limit or preferred value, regardless of whether ranges are
separately disclosed. Where a range of numerical values is recited
herein, unless otherwise stated, the range is intended to include
the endpoints thereof, and all integers and fractions within the
range. It is not intended that the scope of the invention be
limited to the specific values recited when defining a range.
[0033] When the term "about" is used in describing a value or an
end-point of a range, the disclosure should be understood to
include the specific value or end-point referred to.
[0034] As used herein, the terms "comprises," "comprising,"
"includes," "including," "containing," "characterized by," "has,"
"having" or any other variation thereof, are intended to cover a
non-exclusive inclusion. For example, a process, method, article,
or apparatus that comprises a list of elements is not necessarily
limited to only those elements but may include other elements not
expressly listed or inherent to such process, method, article, or
apparatus. Further, unless expressly stated to the contrary, "or"
refers to an inclusive or and not to an exclusive or. For example,
a condition A or B is satisfied by any one of the following: A is
true (or present) and B is false (or not present), A is false (or
not present) and B is true (or present), and both A and B are true
(or present).
[0035] The transitional phrase "consisting of" excludes any
element, step, or ingredient not specified in the claim, closing
the claim to the inclusion of materials other than those recited
except for impurities ordinarily associated therewith. When the
phrase "consists of" appears in a clause of the body of a claim,
rather than immediately following the preamble, it limits only the
element set forth in that clause; other elements are not excluded
from the claim as a whole.
[0036] The transitional phrase "consisting essentially of" limits
the scope of a claim to the specified materials or steps and those
that do not materially affect the basic and novel characteristic(s)
of the claimed invention. "A `consisting essentially of` claim
occupies a middle ground between closed claims that are written in
a `consisting of` format and fully open claims that are drafted in
a `comprising` format."
[0037] Where applicants have defined an invention or a portion
thereof with an open-ended term such as "comprising," it should be
readily understood that (unless otherwise stated) the description
should be interpreted to also describe such an invention using the
terms "consisting essentially of" or "consisting of."
[0038] Use of "a" or "an" are employed to describe elements and
components of the invention. This is done merely for convenience
and to give a general sense of the invention. This description
should be read to include one or at least one and the singular also
includes the plural unless it is obvious that it is meant
otherwise.
[0039] In describing certain polymers it should be understood that
sometimes applicants are referring to the polymers by the monomers
used to make them or the amounts of the monomers used to make them
or by the monomer residues incorporated within them. While such a
description may not include the specific nomenclature used to
describe the final polymer or may not contain product-by-process
terminology, any such reference to monomers, mo nomer residues,
repeat units and amounts should be interpreted to mean that the
polymer is made from those monomers or that amount of the monomers,
and the corresponding polymers and compositions thereof. In this
regard, a reference to a copolymer containing residues of a monomer
is referring to the fact that the copolymer contains repeat units
from that monomer. When applicants refer to a copolymer containing
a percentage of a monomer, it should be understood that this
reference is to the copolymer containing repeat units from that
monomer.
[0040] In describing and/or claiming this invention, the term
"copolymer" is used to refer to polymers containing two or more
monomers.
[0041] The terms "finite amount" and "finite value" are used to
refer to an amount that is greater than zero.
[0042] The term "acid copolymer" is used to refer to a resin
composition comprised of copolymerized residues of an alpha olefin
and copolymerized residues of an alpha,beta-ethylenically
unsaturated carboxylic acid having 3 to 8 carbons. The term
"ionomer" is used herein to refer to a resin composition derived
from a partially or fully neutralized "acid copolymer". It should
be understood that reference to "acid copolymer" is to a
composition that.is not so neutralized.
High Melt Flow Acid Copolymer Compositions
[0043] The invention is related to certain high melt flow acid
copolymer compositions that are useful in forming safety interlayer
sheets or solar cell encapsulant films or sheets. Specifically, the
high melt flow acid copolymer composition is comprised of an acid
copolymer having a MI of about 75 to about 600 g/10 min as measured
by ASTM D1238 at 190.degree. C. and a 2160 g load. (A similar ISO
test is ISO 1133.)
[0044] Acid Copolymer Resins:
[0045] The high Melt flow acid copolymer is comprised of a finite
amount of an alpha olefin and about 1 to about 30 wt % of an
alpha,beta-ethylenically unsaturated carboxylic acid having 3 to 8
carbons, based on the total weight of the copolymer. Preferably,
the acid copolymer comprises about 10 to about 25 wt %, or more
preferably, about 15 to about 23 wt %, or yet more preferably,
about 18 to about 23 wt %, of the alpha,beta-ethylenically
unsaturated carboxylic acid, based on the total weight of the acid
copolymer.
[0046] The alpha olefin comonomers typically incorporate from 2 to
10 carbon atoms. Preferable alpha olefins include, but are not
limited to, ethylene, propylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 3-methyl-1-butene, 4-methyl-1-pentene, and the like and
mixtures thereof. More preferably, the alpha olefin is ethylene.
The alpha,beta-ethylenically unsaturated carboxylic acid comonomers
may include acrylic acid, methacrylic acid, itaconic acid, maleic
acid, maleic anhydride, fumaric acid, monomethyl maleic acid, and
mixtures thereof. Preferable alpha,beta-ethylenically unsaturated
carboxylic acid comonomers include acrylic acid, methacrylic acid
and mixtures thereof.
[0047] The acid copolymers may be polymerized as disclosed in U.S.
Pat. No. 3,404,134; U.S. Pat. No. 5,028,674; U.S. Pat. No.
6,500,888; and U.S. Pat. No. 6,518,365.
[0048] The high melt flow acid copolymers have a MI of about 75 to
about 600 g/10 min, preferably about 100 to about 400 g/10 min.
[0049] Such a high melt flow rate provides the acid copolymer films
or sheets derived therefrom with reduced lamination temperatures,
or shorter cycle time, or both, when they are used in safety
laminates or solar cell laminates. Moreover, when laminated under
the lamination temperatures used herein, films or sheets derived
from such high melt flow acid copolymer compositions possess higher
adhesion strength than those derived from acid copolymer
compositions with relatively lower melt flow rates.
[0050] The high melt flow acid copolymers may optionally contain
other unsaturated comonomers. Specific examples of preferable other
unsaturated comonomers include, but are not limited to, methyl
acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl
methacrylate and mixtures thereof. In general, the acid copolymers
may incorporate 0 to about 50 wt %, or preferably, 0 to about 30 wt
%, or more preferably, 0 to about 20 wt %, of the other unsaturated
comonomer(s), based on the total weight of the copolymer.
[0051] Additives:
[0052] The high melt flow acid copolymer composition may further
comprise one or more additives.
[0053] In one particular embodiment, the acid copolymer composition
further comprises one or more silane coupling agents to further
enhance the adhesion strength of the films or sheets derived
therefrom.
[0054] Exemplary: silane coupling agents that are useful in the
invention include, but are not limited to,
gamma-chloropropylmethoxysilane, vinyltrimethoxysilane,
vinyltriethoxysilane,
vinyltris(beta-methoxyethoxy)silane,gamma-vinylbenzylpropyltrimethoxysila-
ne,
N-beta-(N-vinylbenzylaminoethyl)-gamma-aminopropyltrimethoxysilane,
gamma-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane,
gamma-glycidoxypropyltrimethoxysilane,
gamma-glycidoxypropyltriethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
vinyltrichlorosilane, gamma-mercaptopropylmethoxysilane,
gamma-aminopropyltriethoxysilane,
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, and the like
and mixtures thereof. The silane coupling agents are preferably
incorporated in the acid copolymer compositions at a level of about
0.01 to about 5 wt %, or more preferably, about 0.05 to about 1 wt
%, based on the total weight of the composition.
[0055] It is noted, that the silane coupling agents can reduce the
melt flow rate of the acid copolymer compositions to which they are
incorporated. Therefore, with a set level of silane, the high melt
flow acid copolymer compositions can maintain a certain level of
viscosity than the prior art lower melt flow acid copolymer
compositions.
[0056] In another embodiment of the invention, the acid copolymer
compositions may further comprise additives which effectively
reduce the melt flow of the resin, to the limit of thermosetting
the films or sheets during lamination. The use of such additives
will enhance the upper end-use temperature and reduce creep of the
laminate interlayer sheets or solar cell encapsulant films or
sheets derived therefrom. Typically, the end-use temperature may be
enhanced up to about 20 to about 70.degree. C. In addition, safety
laminates and solar cell laminates produced from such materials
will be fire resistant. Specifically, by thermosetting the acid
copolymer resins during lamination, the resins will have a reduced
tendency to melt and flow out of the laminate, which in turn, may
serve as additional fuel for a fire.
[0057] Typically, the effective melt flow reducing additives are
organic peroxides, such as 2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-di(tert-betylperoxy)hexane-3, di-tert-butyl
peroxide, tert-butylcumyl peroxide,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, dicumyl peroxide,
alpha, alpha'-bis(tert-butyl-peroxyisopropyl)benzene,
n-butyl-4,4-bis(tert-butylperoxy)valerate,
2,2-bis(tert-butylperoxy)butane,
1,1-bis(tert-butyl-peroxy)cyclohexane,
1,1-bis(tert-butylperoxy)-3,3,5-trimethyl-cyclohexane, tert-butyl
peroxybenzoate, benzoyl peroxide, and the like and mixtures
combinations thereof. Preferably the organic peroxides decompose at
a temperature of about 100.degree. C. or higher to generate
radicals. More preferably, the organic peroxides have a
decomposition temperature which affords a half life of 10 hours at
about 70.degree. C. or higher to provide improved stability for
blending operations.
[0058] Moreover, the temperature gap between the acid copolymer
composition compounding temperature and the organic peroxide
decomposition temperature is critical to avoid premature
crosslinking during the compounding and film and sheet formation
processes. In an extrusion process (which is the preferred process
for producing the compositions and manufacturing the high melt flow
acid copolymer films or sheets), the high melt flow acid copolymer
compositions require desirable reduced extrusion temperatures when
compared to the otherwise lower melt flow acid copolymer
compositions and therefore effectively preventing premature
crosslinking during extrusion compounding, film or sheet
formation.
[0059] Preferably, the organic peroxides are added at a level of
about 0.01 to about 10 wt %, or preferably, about 0.5 to about 3.0
wt %, based on the total weight of the composition.
[0060] If desired, initiators, such as dibutyltin dilaurate, may
also be contained in the acid copolymer composition at a level of
about 0.01 to about 0.05 wt %, based on the total weight of the
composition. In addition, if desired, inhibitors, such as
hydroquinone, hydroquinone monomethyl ether, p-benzoquinone, and
methylhydroquinone, may be added for the purpose of enhancing
control to the reaction and stability. Typically, the inhibitors
would be added at a level of less than about 5 wt %, based on the
total weight of the composition.
[0061] In yet another embodiment, the high melt flow acid copolymer
composition may further comprise any other suitable additive(s)
known within the art. Such additives may include, but are not
limited to, plasticizers, processing aides, flow enhancing
additives, lubricants, pigments, dyes, flame retardants, impact
modifiers, nucleating agents, antiblocking agents (e.g., silica),
thermal stabilizers, UV absorbers, UV stabilizers, dispersants,
surfactants, chelating agents, coupling agents, adhesives, primers,
reinforcement additives (e.g., glass fiber), fillers, and the like.
Generally, when used in solar cell encapsulant films or sheets, the
additives that may reduce the optical clarity of the compositions,
such as reinforcement additives and fillers, are reserved for those
films or sheets used as the back encapsulant layers.
[0062] Thermal stabilizers can be used and have been widely
disclosed within the art. Any known thermal stabilizer may find
utility within the invention. Preferable general classes of thermal
stabilizers include, but are not limited to, phenolic antioxidants,
alkylated monophenols, alkylthiomethylphenols, hydroquinones,
alkylated hydroquinones, tocopherols, hydroxylated thiodiphenyl
ethers, alkylidenebisphenols, O-, N- and S-benzyl compounds,
hydroxybenzylated malonates, aromatic hydroxybenzyl compounds,
triazine compounds, aminic antioxidants, aryl amines, diaryl
amines, polyaryl amines, acylaminophenols, oxamides, metal
deactivators, phosphites, phosphonites, benzylphosphonates,
ascorbic acid (vitamin C), compounds that destroy peroxide,
hydroxylamines, nitrones, thiosynergists, benzofuranones,
indolinones, and the like and mixtures thereof. The high melt flow
acid copolymer compositions may contain any effective amount of
thermal stabilizers. Use of a thermal stabilizer is optional and in
some instances is not preferred. When used, the high melt flow acid
copolymer compositions contain at least about 0.05 wt %, and up to
about 10 wt %, more preferably up to about 5 wt %, and most
preferably up to about 1 wt %, of thermal stabilizers, based on the
total weight of the composition.
[0063] UV absorbers can be used and have also been widely disclosed
within the art. Any known UV absorber may find utility within the
invention. Preferable general classes of UV absorbers include, but
are not limited to, benzotriazoles, hydroxybenzophenones,
hydroxyphenyl triazines, esters of substituted and unsubstituted
benzoic acids, and the like and mixtures thereof. The high melt
flow acid copolymer compositions may contain any effective amount
of UV absorbers. Use of a UV absorber is optional and in some
instances is not preferred. When used, the high melt flow acid
copolymer compositions contain at least about 0.05 wt %, and up
about 10 wt %, more preferably up to about 5 wt %, and most
preferably up to about 1 wt %, of UV absorbers, based on the total
weight of the composition.
[0064] Hindered amine light stabilizers (HALS) can be used and have
also been widely disclosed within the art. Generally, Hindered
amine light stabilizers are disclosed to be secondary, tertiary,
acetylated, N-hydrocarbyloxy substituted, hydroxy substituted
N-hydrocarbyloxy substituted, or other substituted cyclic amines
which further incorporate steric hindrance, generally derived from
aliphatic substitution on the carbon atoms adjacent to the amine
function. The high melt flow acid copolymer compositions may
contain any effective amount of hindered amine light stabilizers.
Use of hindered amine light stabilizers is optional and in some
instances is not preferred. When used, the high melt flow acid
copolymer compositions contain at least about 0.05 wt %, and up to
about 10 wt %, more preferably up to about 5 wt %, and most
preferably, up to about 1 wt %, of hindered amine light
stabilizers, based on the total weight of the composition.
High Melt Flow Acid Copolymer Films or Sheets
[0065] The invention further provides shaped articles, such as,
films or sheets comprising the high melt flow acid copolymer
compositions. These high melt flow acid copolymer films and sheets
may be produced by any suitable process. For example, the films and
sheets may be formed through dipcoating, solution casting,
compression molding, injection molding, melts extrusions, melt
blowing, or any other procedures that are known to those of skill
in the art. Preferably, the high melt flow acid copolymer films and
sheets are formed by melt extrusion, which is a particularly
preferred process for formation of "endless" products.
[0066] As discussed above, the high melt flow acid copolymer films
or sheets are useful in forming the interlayer sheets in safety
laminates or encapsulant films or sheets in solar cell laminates.
Moreover, the high melt flow acid copolymer films or sheets may
take the form of single-layer or multilayer films or sheets. By
single-layer, it is meant that the film or sheet has only one
single layer and that the one single layer is made of the high melt
flow acid copolymer composition. By multilayer, it is meant that
the high melt flow acid copolymer film or sheet has two or more
sub-layers and that at least one of the sub-layers is made of the
high melt flow acid copolymer composition. The other sub-layer(s)
of the multilayer film or sheet may be made of any suitable
polymeric compositions. Preferably, however, the other sub-layer(s)
is made of polymeric compositions selected from the group
consisting of acid copolymers and ionomers derived therefrom,
poly(ethylene vinyl acetate), poly(vinyl acetal) (e.g., poly(vinyl
butyral)), polyurethane, polyvinylchloride, polyethylenes (e.g.,
metallocene-catalyzed linear low density polyethylenes), polyolefin
block elastomers, ethylene acrylate ester copolymers (e.g.,
poly(ethylene-co-methyl acrylate) and poly(ethylene-co-butyl
acrylate)), silicone elastomers and epoxy resins. More preferably,
the other sub-layers are formed of polymeric compositions selected
from the group consisting of acid copolymers and ionomers derived
therefrom, poly(ethylene vinyl acetate), metallocene-catalyzed
linear low density polyethylenes, polyolefin block elastomers, and
ethylene acrylate ester copolymers. Moreover, to provide adequate
adhesion strength, at least one, or preferably, both, of the
surface sub-layers of the multilayer film or sheet are formed of
the high melt flow acid copolymer compositions. In one preferred
embodiment, multilayer films and sheets with high flow acid
copolymer surfaces and low flow core layers provide the desirable
low lamination temperatures and high adhesion of the invention.
[0067] The films or sheets of the invention preferably have a total
thickness of about 0.1 mil (0.003 mm) to about 250 mils (6.35 mm).
When used as a safety laminate interlayer sheet, the high melt flow
acid copolymer sheet preferably has a total thickness of about 10
mils (0.25 mm) to about 250 mils (6.35 mm), or more preferably,
about 15 mils (0.38 mm) to about 90 mils (2.28 mm), or yet more
preferably, about 30 mils (0.76 mm) to about 60 mils (1.52 mm).
Also in accordance to the invention, for use as a solar cell
encapsulant the sheet or film preferably has a thickness of about
0.1 mil (0.003 mm) to about 20 mils (0.51 mm). That is, when used
in a flexible solar cell laminate as a solar cell encapsulant film,
the high melt flow acid copolymer film preferably has a total
thickness of about 0.1 mil (0.003 mm) to about 10 mils (0.25 mm),
or more preferably, about 1 mil (0.03 mm) to about 5 mils (0.13
mm), while when used in a rigid solar cell laminate as a solar cell
encapsulant sheet, the high melt flow acid copolymer sheet
preferably has a total thickness of about 10 mils (0.25 mm) to
about 20 mils (0.51 mm). The thickness of the individual sub-layers
that make up the total multilayer acid copolymer film or sheet is
not critical and may be independently varied depending on the
particular application: Preferably, however, the surface layers of
a multilayer film or sheet should have a thickness of about 1 mil
(0.03 mm) to about 5 mils (0.13 mm).
[0068] The high melt flow acid copolymer films or sheets may have
smooth or rough surfaces on one or both sides. Preferably, the high
melt flow films or sheets have rough surfaces to facilitate the
de-airing of the laminates through the laminate process. Providing
channels for the escape of air and removing air during lamination
is a known method for obtaining laminates having acceptable
appearance. Rough surfaces can be effected by mechanically
embossing or by melt fracture during extrusion of the interlayer
sheet or encapsulant film or sheet followed by quenching so that
the roughness is retained during handling. The surface pattern can
be applied to the high melt flow acid copolymer film or sheet
through common art processes. For example, the as extruded film or
sheet may be passed over a specially prepared surface of a die roll
positioned in close; proximity to the exit of the die which imparts
the desired surface characteristics to one side of the molten
polymer. Thus, when the surface of such roll has minute peaks and
valleys, film or sheet formed of polymer cast thereon will have a
rough surface on the side which contacts the roll which generally
conforms respectively to the valleys and peaks of the roll surface.
Such die rolls are disclosed in, e.g., U.S. Pat. No. 4,035,549.
[0069] If desired, one or both surfaces of the high melt flow acid
copolymer film or sheet may be treated to enhance the adhesion to
other laminate layers. This treatment may take any form known
within the art, including adhesives, primers, such as silanes,
flame treatments (see, e.g., U.S. Pat. Nos. 2,632,921; U.S. Pat.
No. 2,648,097; U.S. Pat. No. 2,683,894; and U.S. Pat. No.
2,704,382), plasma treatments (see e: g., U.S. Pat. No. 4,732,814),
electron beam treatments, oxidation treatments, corona discharge
treatments, chemical treatments, chromic acid treatments, hot air
treatments, ozone treatments, ultraviolet light treatments, sand
blast treatments, solvent treatments, and the like and combinations
thereof. For example, a thin layer of carbon may be deposited on
one or both surfaces of the film or sheet through vacuum sputtering
as disclosed in U.S. Pat. No. 4,865,711. U.S. Pat. No. 5,415,942,
on the other hand, discloses a hydroxy-acrylic hydrosol primer
coating that may serve as an adhesion-promoting primer for
poly(ethylene terephthalate) films.
[0070] The adhesive layer preferably can take the form of a
monolayer of an adhesive primer or of a coating. The
adhesive/primer coating may be less than 1 mil (0.03 mm), or
preferably, less than 0.5 mil (0.013 mm), or more preferably, less
than 0.1 mil (0.003 mm), thick. The adhesives may be any adhesive
or primer known within the art. Preferably, the adhesives or
primers are silane coupling agents or poly(vinyl amine) or
poly(allyl amine). The poly(allyl amine)-based primers and their
application to poly(ethylene terephthalate) polymeric films are
disclosed within U.S. Pat. No. 5,411,845; U.S. Pat. No. 5,770,312;
U.S. Pat. No. 5,690,994; and U.S. Pat. No. 5,698,329.
Safety Laminates
[0071] The invention further provides safety laminates comprising a
polymeric interlayer sheet formed of the high melt flow acid
copolymer composition. Specifically, the safety laminate of the
invention comprises at least one rigid sheet layer and at least one
layer of the high melt flow acid copolymer sheet that is described
above as an interlayer sheet.
[0072] As discussed above, at the lamination temperatures used
herein, the high melt flow acid copolymer interlayer sheets
typically possess higher adhesion strength than those sheets
derived from otherwise low melt flow acid copolymers, and therefore
providing the safety laminate structures with improved shock
resistance.
[0073] In accordance to the invention, the rigid sheets can be
glass or rigid plastic sheets, such as, polycarbonate, acrylics,
polyacrylate, cyclic polyolefins (e.g., ethylene norbornene
polymers), metallocene-catalyzed polystyrene, polyamides,
polyesters, fluoropolymers and the like and combinations thereof.
Metal sheets (such as, aluminum, steel or galvanized steel) or
ceramic plates may be substituted for the rigid polymeric sheet or
glass.
[0074] The term "glass" is meant to include not only window glass,
plate glass, silicate glass, sheet glass, low iron glass, tempered
glass, tempered CeO-free glass, and float glass, but also to
include colored glass, specialty glass (such as those include
ingredients to control, e.g., solar heating), coated glass (such as
those sputtered with metals (e.g., silver or indium tin oxide) for
solar control purposes), E-glass, Toroglass, Solex.RTM. glass (a
product of Solutia). Such specialty glasses are disclosed in, e.g.,
U.S. Pat. No. 4,615,989; U.S. Pat. No. 5,173,212; U.S. Pat. No.
5,264,286; U.S. Pat. No. 6,150,028; U.S. Pat. No. 6,340,646; U.S.
Pat. No. 6,461,736; and U.S. Pat. No. 6,468,934. It is understood,
however, that the type of glass to be selected for a particular
laminate depends on the intended use.
[0075] One preferred embodiment of the invention is a safety
laminate comprising at least one layer of glass, and at least one
layer of the high melt flow acid copolymer sheet described above.
Preferably, the high melt flow acid copolymer sheet is self-adhered
to the glass. As used herein, when the a polymeric sheet is said to
be "self-adhered" to the glass, it is meant that there is no
intermediate layer such as a primer or thin adhesive layer between
the glass and the polymeric layer, nor has the surface of the glass
or polymeric layer been specially treated. A more preferred
embodiment of the invention is a laminate comprising two layers of
glass and at least one layer of the high melt flow acid copolymer
sheets bonded in between. Preferably, the high melt flow acid
copolymer sheet is self-adhered to one or both of the glass
layers.
[0076] The safety laminate of the invention may further comprise
other optional interlayer- sheets and/or film layers. The other
optional interlayer sheets may be formed of any suitable materials,
such as, acid copolymers and ionomers derived therefrom,
poly(ethylene vinyl acetate), poly(vinyl acetal) (e.g., poly(vinyl
butyral)), polyurethane, polyvinylchloride, polyethylenes (e.g.,
metallocene-catalyzed linear low density polyethylenes), polyolefin
block elastomers, ethylene acrylate ester copolymers (e.g.,
poly(ethylene-co-methyl acrylate) and poly(ethylene-co-butyl
acrylate)), silicone elastomers and epoxy resins. In one preferred
embodiment, the other interlayer is an acid copolymer composition
comprising acid copolymer of an alpha olefin and about 1 to about
30 wt % of alpha,beta-ethylenically unsaturated carboxylic acid
having 3 to 8 carbons, based on the total weight of the acid
copolymer, wherein the acid copolymer has a Melt Index of about 75
to about 600 g/10 min, and may be the same or different than the
one used in the first layer. The thickness of the other optional
interlayer sheet(s) is not critical and may be independently varied
depending on the particular application. The values provided above
for the acid copolymer layer are preferred in many instances.
[0077] The film layers used in the safety laminates may be metal,
such as aluminum foil, or polymeric. Preferable polymeric film
materials include, but are not limited to, polyesters (e.g.,
poly(ethylene terephthalate) (PET)), poly(ethylene naphthalate),
polycarbonate, polyolefins (e.g., polypropylene, polyethylene, and
cyclic polyolefins), norbornene polymers, polystyrene (including
syndiotactic polystyrene), styrene-acrylate copolymers,
acrylionitrile-styrene copolymers, polysulfones (e.g.,
polyethersulfone, polysulfone, etc.), nylons, poly(urethanes),
acrylics, cellulose acetates (e.g., cellulose acetate, cellulose
triacetates, etc.), cellophane, vinyl chloride polymers (e.g.,
polyvinylidene chloride, vinylidene chloride copolymers, etc.),
fluoropolymers (e.g., polyvinyl fluoride, polyvinylidene fluoride,
polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymers,
etc.) and the like. More preferably, the polymeric film is a
biaxially oriented poly(ethylene terephthalate) film.
[0078] The thickness of the polymeric film is not critical and may
be varied depending on the, particular application. In general,
however, the thickness of the polymeric film may range from about
0.1 mils (0.003 mm) to about 10 mils (0.26 mm), or preferably, from
about 1 mil (0.025 mm) to about 7 mils (0.18 mm).
[0079] In addition, the polymeric films are sufficiently
stress-relieved and shrink-stable under the coating and lamination
processes. Preferably, the polymeric films are heat stabilized to
provide low shrinkage characteristics when subjected to elevated
temperatures (i.e. less than 2% shrinkage in both directions after
30 min at 150.degree. C.).
[0080] The films may also be coated if desired. For example, the
films may be coated with organic infrared absorbers and sputtered
metal layers, such as silver, coatings and the like. Metal coated
polymeric films are disclosed in, e.g., U.S. Pat. No. 3,718,535;
U.S. Pat. No. 3,816,201; U.S. Pat. No. 4,465,736; U.S. Pat. No.
4,450,201; U.S. Pat. No. 4,799,745; U.S. Pat. No. 4,846,949; U.S.
Pat. No. 4,954,383; U.S. Pat. No. 4,973,511; U.S. Pat. No.
5,071,206; U.S. Pat. No. 5,306,547; U.S. Pat. No. 6,049,419; U.S.
Pat. No. 6,104,530; U.S. Pat. No. 6,204,480; U.S. Pat. No.
6,255,031; and U.S. Pat. No. 6,565,982. For example, the coating
may function as oxygen and moisture barrier coatings, such as the
metal oxide coating disclosed within U.S. Pat. No. 6,521,825; U.S.
Pat. No. 6,818,819; and EP 1 182 710.
[0081] If desired, one or both surfaces of laminate layers, such as
the acid copolymer interlayer sheet(s), the optional other
interlayer sheet(s) or film layer(s), or the rigid sheet(s), may be
treated to enhance their adhesion strength, as described above.
[0082] The safety laminate of the invention may take any form known
within the art. Preferable specific glass laminate constructions
include, for example, wherein "HMFAC" means the preferable high
melt flow acid copolymer comprising interlayer sheet and multilayer
sheet, as described above,
[0083] glass/HMFAC;
[0084] glass/HMFAC/film;
[0085] glass/HMFAC/glass;
[0086] glass/HMFAC/film/HMFAC/glass;
[0087] glass/HMFAC/film/HMFAC/film; and the like.
[0088] The safety laminates of the invention may be produced by any
of the lamination process that are described below in detail, or by
other processes.
Solar Cell Pre-Laminate Assemblies and Solar Cell Laminates
[0089] The invention further provides a solar cell pre-laminate
assembly which comprises a solar cell component formed of one or a
plurality solar cells and at least one layer, of the high melt flow
acid copolymer film or sheet that is described above.
[0090] Solar cells are commonly available on an ever increasing
variety as the technology evolves and is optimized. Within the
invention, a "solar cell" is meant to include any article which can
convert light into electrical energy. Typical art examples of the
various forms of solar cells include, for example, single crystal
silicon solar cells, polycrystal silicon solar cells, microcrystal
silicon solar cells, amorphous silicon based solar cells, copper
indium selenide solar cells, compound semiconductor solar cells,
dye sensitized solar cells, and the like. The most common types of
solar cells include multi-crystalline solar cells, thin film solar
cells, compound semiconductor solar cells and amorphous silicon
solar cells due to relatively low cost manufacturing ease for large
scale solar cells.
[0091] Thin film solar cells are typically produced by depositing
several thin film layers onto a substrate, such as glass or a
flexible film, with the layers being patterned so as to form a
plurality of individual cells which are electrically interconnected
to produce a suitable voltage output. Depending on the sequence in
which the multi-layer deposition is carried out, the substrate may
serve as the rear surface or as a front window for the solar cell
module. By way of example, thin film solar cells are disclosed in
U.S. Pat. No. 5,512,107; U.S. Pat. No. 5,948,176; U.S. Pat. No.
5,994,163; U.S. Pat. No. 6,040,521; U.S. Pat. No. 6,137,048; and
U.S Pat. No. 6,258,620. Examples of thin film solar cell modules
are those that comprise cadmium telluride or CIGS,
(Cu(In-Ga)(SeS)2), thin film cells.
[0092] In one particular embodiment, the solar cell pre-laminate
assembly comprises one layer of the high melt flow acid copolymer
film or sheet, which is positioned next to the solar cell component
and serves as one of the encapsulant layers, or preferably, the
high melt flow acid copolymer film or sheet is positioned next to
the solar cell component at the light-receiving side and serves as
the front encapsulant layer.
[0093] In accordance to the invention, besides the at least one
high melt flow acid copolymer film or sheet, the solar cell
pre-laminate assembly may optionally further comprise encapsulant
layers formed of other polymeric materials, such as, acid
copolymers and ionomers derived therefrom, poly(ethylene vinyl
acetate), poly(vinyl acetal) (e.g., poly(vinyl butyral), including
acoustic grades of poly(vinyl butyral)), polyurethane (PU), poly
vinyl chloride, polyethylenes (e.g., linear low density
metallocene-catalyzed polyethylenes), polyolefin block elastomers,
ethylene acrylate ester copolymers (e.g., poly(ethylene-co-methyl
acrylate) and poly(ethylene-co-butyl acrylate)), silicone
elastomers and epoxy resins.
[0094] In a further embodiment, the solar cell pre-laminate
assembly comprises two layers of the high melt flow acid copolymer
film or sheet, wherein each of the two high melt flow acid
copolymer films or sheets are laminated to each of the two sides of
the solar cell component and serve as the front and back
encapsulant layers.
[0095] The thickness of the individual encapsulant layers other
than the high melt flow acid copolymer film(s) or sheet(s) is not
critical and may be independently varied depending on the
particular application. Preferably, the thickness of each of these
encapsulant layers may independently range from about 1 mil (0.026
mm) to about 120 mils (3.00 mm), or more preferably, from about 1
mil to about 40 mils (1.02 mm), or most preferably, from about 1
mil to about 20 mils (0.51 mm). In addition, all the encapsulant
layer(s) comprised in the solar cell pre-laminate assemblies, may
have smooth or roughened surfaces. Preferably, however, the
encapsulant layer(s) have roughened surfaces to facilitate the
de-airing of the laminates through the lamination process.
[0096] In yet a further embodiment, the solar cell pre-laminate
assembly may further comprise an incident layer and/or a backing
layer serving as the outer layers of the assembly at the
light-receiving side and the back side, respectively.
[0097] The outer layers of the solar cell pre-laminate assemblies,
i.e., the incident layers and the backing layer, may be derived
from any suitable sheets or films. Suitable sheets may be glass or
plastic sheets, such as, polycarbonate, acrylics, polyacrylate,
cyclic polyolefins (e.g., ethylene norbornene polymers),
metallocene-catalyzed polystyrene, polyamides, polyesters,
fluoropolymers and the like and combinations thereof. In addition,
metal sheets, such as aluminum, steel, galvanized steel, or ceramic
plates may be utilized in forming the back-sheet.
[0098] Suitable film layers may be polymeric. Preferred polymers
used to form the polymeric films, include but are not limited to,
polyesters (e.g., poly(ethylene terephthalate)), poly(ethylene
naphthalate), polycarbonate, polyolefins (e.g., polypropylene,
polyethylene, and cyclic polyolefins), norbornene polymers,
polystyrene (including syndiotactic polystyrene), styrene-acrylate
copolymers, acrylonitrile-styrene copolymers, polysulfones (e.g.,
polyethersulfone, polysulfone, etc.), nylons, poly(urethanes),
acrylics, cellulose acetates (e.g., cellulose acetate, cellulose
triacetates, etc.), cellophane, vinyl chloride polymers (e.g.,
polyvinylidene chloride, vinylidene chloride copolymers, etc.),
fluoropolymers (e.g., polyvinyl fluoride, polyvinylidene fluoride,
polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymers,
etc.) and the like. Most preferably, the polymeric film is
biaxially oriented polyester film (preferably poly(ethylene
terephthalate film) or a fluoropolymer film (e.g., Tedlar.RTM.,
Tefzel.RTM., and Teflon.RTM. films, from E. I. du Pont de Nemours
and Company, Wlilmington, Del. (DuPont)).
Fluoropolymer-polyester-fluoropolymer ("TPT") films are also
preferred for some applications. Metal films, such as aluminum foil
may also be used herein as the back-sheet.
[0099] The solar cell pre-laminate assembly of the invention, may
optionally further comprise other functional film or sheet layers
(e.g., dielectric layers or barrier layers) embedded within the
assembly. Such functional layers may be derived from any of the
above mentioned polymeric films or those that are coated with
additional functional coatings. For example, poly(ethylene
terephthalate) films coated with a metal oxide coating, such as
those disclosed within U.S. Pat. No. 6,521,825; U.S. Pat. No.
6,818,819; and EP 1 182 710, may function as oxygen and moisture
barrier layers in the laminates.
[0100] If desired, a layer of non-woven glass fiber (scrim) may
also be included in the solar cell laminates to facilitate
de-airing during the lamination process or to serve as
reinforcement for the encapsulant layer(s). The use of such scrim
layers within solar cell laminates is disclosed within, e.g., U.S.
Pat. No. 5,583,057; U.S. Pat. No. 6,075,202; U.S. Pat. No.
6,204,443; U.S. Pat. No. 6,320,115; U.S. Pat. No. 6,323,416; and EP
0 769 818.
[0101] In addition, it is understood that all the film or sheet
layers positioned to the light-receiving side of the solar cell
layer are made of transparent material to allow efficient
transmission of sunlight into the solar cell component. In some
instances, a special film or sheet may be included to serve both
the function of an encapsulant layer and an outer layer. It is also
conceivable that any of the film or sheet layers included in the
assembly may be in the form of a pre-formed single-layer or
multi-layer film or sheet.
[0102] If desired, one or both surfaces of the laminate layers of
the solar cell pre-laminate assemblies may be treated to enhance
the adhesion strength, as described above.
[0103] The solar cell pre-laminate assemblies may take any form
known within the art. Preferable specific solar cell pre-laminate
constructions (top (light incident) side to back side) include, for
example, wherein "HMFAC" means the high melt flow acid copolymer
encapsulant film, multilayer film, sheet and multilayer sheet of
the invention, as described above,
[0104] glass/HMFAC/solar cell/HMFAC/glass;
[0105] glass/HMFAC/solar cell/HMFAC/Tedlar.RTM. film;
[0106] Tedlar.RTM. film/HMFAC/solar cell/HMFAC/glass;
[0107] Tedlar.RTM. film/HMFAC/solar cell/HMFAC/ Tedlar.RTM.
film;
[0108] glass/HMFAC/solar cell/HMFAC/PET film;
[0109] Tedlar.RTM. film/HMFAC/solar cell/HMFAC/PET film;
[0110] glass/HMFAC/solar cell/HMFAC/barrier coated
film/HMFAC/glass;
[0111] Tedlar.RTM. film/HMFAC/barrier coated film/HMFAC/solar
cell/HMFAC/barrier coated film/HMFAC/Tedlar.RTM. film;
[0112] glass/HMFAC/solar cell/HMFAC/aluminum stock;
[0113] Tedlar.RTM. film/HMFAC/solar cell/HMFAC/aluminum stock;
[0114] glass/HMFAC/solar cell/HMFAC/galvanized steel sheet;
[0115] glass/HMFAC/solar cell/HMFAC/PET film/HMFAC/aluminum
stock;
[0116] Tedlar.RTM. film/HMFAC/solar cell/HMFAC/PET
film/HMFAC/aluminum stock;
[0117] glass/HMFAC/solar cell/HMFAC/PET film/HMFAC/galvanized steel
sheet;
[0118] Tedlar.RTM. film/HMFAC/solar cell/HMFAC/PET
film/HMFAC/galvanized steel sheet;
[0119] glass/HMFAC/solar cell/acoustic poly(vinyl butyral)
encapsulant layer/glass;
[0120] glass/HMFAC/solar cell/poly(vinyl butyral) encapsulant
layer/Tedlar.RTM. film;
[0121] Tedlar.RTM. film/HMFAC/solar cell/acid copolymer encapsulant
layer/Tedlar.RTM. film;
[0122] glass/HMFAC/solar cell/ethylene vinyl acetate encapsulant
layer/PET film;
[0123] Tedlar.RTM. film/HMFAC/solar cell/poly(ethylene-co-methyl
acrylate) encapsulant layer/PET film;
[0124] glass/poly(ethylene-co-butyl acrylate) encapsulant
layer/solar cell/HMFAC/barrier coated film/poly(ethylene-co-butyl
acrylate) encapsulant layer/glass; and the like. While reference in
the above examples is to the preferred Tedlar.RTM. fluoropolymer
film, it should be readily recognized that the above embodiments
can also be made with other fluoropolymer film, such as a
fluoropolymer-polyester-fluoropolymer trilayer film. While
reference in the above examples is to the preferred
poly(terephthalate) film, it should be readily recognize that any
polyester film can be used. In addition, the term "glass" is
intended to refer to sheets of any of the aforementioned types of
glass or glass alternatives.
[0125] The invention further provides solar cell laminates derived
from the solar cell pre-laminate assemblies disclosed above.
Specifically the solar cell laminates are formed by subjecting the
solar cell pre-laminate assemblies to further lamination process,
as provided below in detail.
[0126] Moreover, as discussed above, under the lamination
temperature used herein, the high melt flow acid copolymer
encapsulant films or sheets typically possess higher adhesion
strength than those encapsulant films or sheets derived from
otherwise low melt flow acid copolymers at the reduced lamination
conditions described herein, and therefore provide solar cell
laminate structures with a simplified production process.
Lamination Process
[0127] The invention further provides a simplified process for
producing the safety laminates or solar cell laminates.
Specifically, as provided above, the incorporation of the high melt
flow acid copolymer interlayer sheets or high melt flow acid
copolymer solar cell encapsulant films or sheets requires reduced
lamination temperatures, or cycle time, or both compared to the
lamination temperatures or cycle times used in the process
involving low melt flow acid copolymers.
[0128] In accordance to the invention, the lamination process may
be an autoclave or non-autoclave process.
[0129] In an exemplary process, a glass sheet, a front encapsulant
layer, a solar cell component, a back encapsulant layer and a
backing layer (e.g., Tedlar.RTM. film), and a cover glass sheet are
laid up and laminated together under heat and pressure and a vacuum
(for example, in the range of about 27-28 inches (689-711 mm) Hg)
to remove air. Preferably, the glass sheet has been washed and
dried. A typical glass type is 90 mil thick annealed low iron
glass. In an exemplary procedure, the pre-laminate assembly of the
invention is placed into a bag capable of sustaining a vacuum ("a
vacuum bag"), drawing the air out of the bag using a vacuum line or
other means of pulling a vacuum on the bag, sealing the bag while
maintaining the vacuum, placing the sealed bag in an autoclave at a
temperature of about 100.degree. C. to about 180.degree. C., at a
pressure of about 150-about 250 psi, preferably about 200 psi
(about 15 bars), for about 10 to about 50 minutes. Preferably the
bag is autoclaved at a temperature of about 100.degree. C. to about
120.degree. C. for about 20 to about 45 minutes. More preferably
the bag is autoclaved at a temperature of about 110.degree. C. to
about 120.degree. C. for about 20 to about 40 minutes. A vacuum
ring may be substituted for the vacuum bag. One type of vacuum bags
is disclosed within U.S. Pat. No. 3,311,517. The high melt flow
acid copolymer films and sheets of the invention provides the
desirable advantage of lower lamination temperatures and/or faster
lamination cycle times, depending on the laminator's choice.
[0130] Any air trapped within the pre-laminate assembly may be
removed through a nip roll process. For example, the pre-laminate
assembly may be heated in an oven at a temperature of about
80.degree. C. to about 120.degree. C., or preferably, at a
temperature of between about 90.degree. C. and about 100.degree.
C., for about 15-60 (preferably about 30) minutes. Thereafter, the
heated pre-laminate assembly is passed through a set of nip rolls
so that the air in the void spaces between the solar cell outside
layers, the solar cell component, and the encapsulant layers may be
squeezed out, and the edge of the assembly sealed. This process may
provide the final solar cell module or may provide what is referred
to as a pre-press assembly, depending on the materials of
construction and the exact conditions utilized.
[0131] The pre-press assembly may then be placed in an air
autoclave where the temperature is raised to about 100.degree. C.
to about 160.degree. C., or preferably, between about 110.degree.
C. and about 120.degree. C., and pressure to between about 100 psig
and about 300 psig, or preferably, about 200 psig (14.3 bar). These
conditions are maintained for about 15 minutes to about 1 hour, or
preferably, about 20 to about 50 minutes, after which, the air is
cooled while no more air is added to the autoclave. After about
10-30 (preferably about 20) minutes of cooling, the excess air
pressure is vented and the solar cell laminates are removed from
the autoclave. This should not be considered limiting. Essentially
any lamination process known within the art may be used herein.
[0132] A non-autoclave lamination process has been disclosed, e.g.,
within U.S. Pat. No. 3,234,062; U.S. Pat. No. 3,852,136; U.S. Pat.
No. 4,341,576; U.S. Pat. No. 4,385,951; U.S. Pat. No. 4,398,979;
U.S. Pat. No. 5,536,347; U.S. Pat. No. 5,853,516; U.S. Pat. No.
6,342,116; U.S. Pat. No. 5,415,909; U.S. Pat. No. 2004-0182493;
U.S. Pat. No. 2003-0148114 A1; EP 1 235 683 B1; WO 91/01880; and WO
03/057478 A1. Generally, the non-autoclave process includes heating
the pre-laminate assembly or the pre-press assembly and,
optionally, the application of vacuum, pressure or both. For
example, the pre-press may be successively passed through heating
ovens and nip rolls. A commercial example of a photovoltaic
lamination process includes the Icolam vacuum laminating systems of
Meier Vakuumtechnik GmbH (Bocholt, Germany).
[0133] In producing solar cell laminates, if desired, the edges of
the laminates may be sealed to reduce moisture and air intrusion
and the potential degradation effect on the efficiency and lifetime
of the solar cell(s) by any means disclosed within the art.
Suitable edge seal materials include, but are hot limited to, butyl
rubber, polysulfide, silicone, polyurethane, polypropylene
elastomers, polystyrene elastomers, block elastomers,
styrene-ethylene-butylene-styrene (SEBS), and the like.
EXAMPLES
[0134] The following Examples and are intended to be illustrative
of the invention, and are not intended in any way to limit the
scope of the invention.
Methods
[0135] The following methods are used in the Examples presented
hereafter.
Melt Index
[0136] Melt Index (MI) is measured by ASTM D1238 at 190.degree. C.
and a 2160 g load. A similar ISO test is ISO 1133.
I. Lamination Process 1:
[0137] The laminate layers described below are stacked (laid up) to
form the pre-laminate assembly described within the examples. For
the assembly containing a film layer as the incident or back-sheet
layer, a cover glass sheet is placed over the film layer. The
pre-laminate assembly is then placed within a Meier ICOLAM 10/08
laminator (Meier Vakuumtechnik GmbH, Bocholt, Germany). The
lamination cycle includes an evacuation step (vacuum of 3 in. Hg)
of 5.5 minutes and a pressing stage (pressure of 1000 mb) of 5.5
minutes at a temperature of 115.degree. C. For Examples 9,11, 41
and 43 only, an additional step at 145.degree. C. for 5 minutes
while maintaining the pressing conditions is incorporated to cure
the composition. The laminate is then removed.
II. Lamination Process 2:
[0138] The laminate layers described below are stacked (laid up) to
form the pre-laminate assemblies described within the examples. For
the assembly containing a film layer as the incident or back-sheet
layer, a cover glass sheet is placed over the film layer. The
pre-laminate assembly is then placed within a vacuum bag, the
vacuum bag is sealed and a vacuum is applied to remove the air from
the vacuum bag. The bag is placed into an oven and heated to
90-100.degree. C. for 30 minutes to remove any air contained
between the assembly. The pre-press assembly is then subjected to
autoclaving at 115.degree. C. for 30 minutes in an air autoclave to
a pressure of 200 psig (14.3 bar), as described above. The air is
then cooled while no more air is added to the autoclave. After 20
minutes of cooling when the air temperature reaches less than about
50.degree. C., the excess pressure is vented, and the laminate is
removed from the autoclave.
EXAMPLES 1-15:,
[0139] The 12.times.12 in (305.times.305 mm) laminate structures
described below in Table 1 are assembled and laminated by
Lamination Process 1, above.
TABLE-US-00001 TABLE 1 Laminate Structures Example Layer 1 Layer 2
Layer 3 Layer 4 Layer 5 1, 16 Glass 1 HMFAC 1 HMFAC 1 Glass 1 2, 17
Glass 1 HMFAC 2 Glass 1 3, 18 Glass 2 HMFAC 3 PET 1 HMFAC 3 Glass 2
4, 19 Glass 3 HMFAC 4 EVA HMFAC 4 Glass 1 5, 20 Glass 1 HMFAC 5
HMFAC 5 PET 2 6, 21 Glass 2 HMFAC 6 Glass 2 7, 22 Glass 1 HMFAC 7
PET 3 8, 23 Glass 1 HMFAC 8 EBA HMFAC 8 Glass 1 9, 24 Glass 1 HMFAC
9 Glass 1 10, 25 Glass 2 HMFAC 10 PET 4 PVB PET 1 11, 26 Glass 1
HMFAC 12 HMFAC 11 HMFAC 12 Glass 1 12, 27 Glass 2 HMFAC 13 EBA
HMFAC 13 PET 5 13, 28 Glass 1 HMFAC 14 PET 6 HMFAC 14 Glass 1 14,
29 Glass 3 HMFAC 15 PET 1 HMFAC 15 Glass 2 15, 30 Glass 1 HMFAC 16
HMFAC 16 Glass 1
[0140] HMFAC 1 is a 20 mil (0.51 mm) thick embossed sheet of Acid
Copolymer A, a poly(ethylene-co-methacrylic acid) containing 15 wt
% of polymerized residues of methacrylic acid and having a MI of
100 g/10 min.
[0141] HMFAC 2 is a 60 mil (-1.52 mm) thick embossed tri-layer
sheet having (i) two (2) 1 mil (0.03 mm) thick surface layers
formed of a blend of Acid Copolymer B, a
poly(ethylene-co-methacrylic acid) containing 18 wt % of
polymerized residues of methacrylic acid and having a MI of 220
g/10 min, and 0.15 wt % of TINUVIN 328 (Ciba Specialty Chemicals
Company), based on the total weight of the blend and (ii) a core
layer of a poly(ethylene-co-isobutyl acrylate-co-methacrylic acid)
containing 10 wt % of polymerized residues of isobutyl acrylate and
10 wt % of polymerized residues of methacrylic acid that is 70%
neutralized with zinc ions and having a MI of 1 g/10 min.
[0142] HMFAC 3 is a 15 mil (0.38 mm) thick embossed tri-layer sheet
having (i) two (2) 1 mil (0.03 mm) thick surface layers of Acid
Copolymer C, poly(ethylene-co-methacrylic acid) containing 22 wt %
of polymerized residues of methacrylic acid and having a MI of 400
g/10 min and (ii) a core layer of a poly(ethylene-co-n-butyl
acrylate) containing 35 wt % of n-butyl acrylate and having a MI of
3 g/10 min.
[0143] HMFAC 4 is a 1 mil (0.03 mm) thick film of Acid Copolymer D,
a poly(ethylene-co-methacrylic acid) containing 19 wt % of
polymerized residues of methacrylic acid and having a MI of 150
g/10 min.
[0144] HMFAC 5 is a 20 mil (0.51 mm) thick embossed sheet of Acid
Copolymer E, a composition comprising 99.5 wt % of Acid Copolymer A
and 0.5 wt % of
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, based on the
total weight of the composition.
[0145] HMFAC 6 is a 90 mil (2.25 mm) thick embossed tri-layer sheet
having (i) two (2) 1 mil (0.03 mm) thick surface layers of Acid
Copolymer F, a composition comprising 99.25 wt % of Acid Copolymer
B and 0.25 wt % of
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, based on the
total weight of the composition and (ii) a core layer of a
poly(ethylene-co-methacrylic acid) containing 22 wt % of
polymerized residues of methacrylic acid that is 35% neutralized
with sodium ion and having a MI of 1.5 g/10 min.
[0146] HMFAC 7 is a 20 mil (0.51 mm) thick embossed tri-layer sheet
having (i) two (2) 1 mil (0.03 mm) thick surface layers of Acid
Copolymer G, a composition comprising 99.875 wt % of Acid Copolymer
C and 0.125 wt % of
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, based on the
total weight of the composition and (ii) a core layer of
poly(ethylene-co-methyl acrylate) containing 25 wt % of polymerized
residues of methyl acrylate and having a MI of 5 g/10 min.
[0147] HMFAC 8 is a 1 mil (0.03 mm) thick film of Acid Copolymer H,
a composition comprising 99.875 wt % of Acid Copolymer D, 0.30 wt %
of TINUVIN 1577, 0.30 wt % of CHIMASSORB 944 (products of the Ciba
Specialty Chemicals Company), and 0.125 wt % of
gamma-glycidoxypropyltriethoxysilane, based on the total weight of
the composition.
[0148] HMFAC 9 is a 90 mil (2.25 mm) thick embossed tri-layer sheet
having (i) two (2) 1 mil, (0.03 mm) thick surface layers of Acid
Copolymer E and (ii) a core layer of Acid Copolymer I, a
composition comprising 98.5 wt % of Acid Copolymer A and 1.5 wt %
of 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, based on the
total weight of the composition.
[0149] HMFAC 10 is a 15 mil (0.38 mm) thick embossed sheet of Acid
Copolymer J, a composition comprising 98.0 wt % of Acid Copolymer B
and 2.0 wt % of 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,
based on the total weight of the composition.
[0150] HMFAC 11 is a 20 mil (0.51 mm) thick embossed sheet of Acid
Copolymer K, a composition comprising 95 wt % of Acid Copolymer C,
0.5 wt % of CYASORB UV-1164 (Cytec Industries), 2.5 wt % of
trimethylolpropane triacrylate, and 2.5 wt % of
1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, based on the
total weight of the composition.
[0151] HMFAC 12 is a 1 mil (0.03 mm) thick film of Acid Copolymer
L, a composition comprising 93.0 wt % of Acid Copolymer D, 5.0 wt %
of triallyl isocyanurate and 2.0 wt % of
1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, based on the
total weight of the composition.
[0152] HMFAC 13 is a 1 mil (0.03 mm) thick film of Acid Copolymer
M, a composition comprising 98.0 wt % of Acid Copolymer A, 0.5 wt %
of vinyltrimethoxysilane, and 1.5 wt % of
1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, based on the
total weight of the composition.
[0153] HMFAC 14 is a 20 mil (0.51 mm) thick embossed sheet of Acid
Copolymer N, a composition comprising 97.75 wt % of Acid Copolymer
B, 0.25 wt % of gamma-methacryloxypropyltrimethoxysilane, and 2.0
wt % of 1,1 -bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, based
on the total weight of the composition.
[0154] HMFAC 15 is a 15 mil (0.38 mm) thick embossed sheet of Acid
Copolymer O, a composition comprising 97.375 wt % of Acid Copolymer
C, 0.125 wt % of
N-beta-(N-vinylbenzylaminoethyl)-gamma-aminopropyltrimethoxysilane,
and 2.5 wt % of 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,
based on the total weight of the composition.
[0155] HMFAC 16 is a 90 mil (2.25 mm) thick embossed sheet of Acid
Copolymer P, a composition comprising 94.875 wt % of Acid Copolymer
D, 3 wt % of trimethylolpropane triacrylate, 0.125 wt % of
N-beta-(N-vinylbenzylaminoethyl)-gamma-aminopropyltrimethoxysilane,
CYASORB UV-1164, and TINUVIN 123, and 2.0 wt % of 1,1
-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, based on the total
weight of the composition.
[0156] EBA is a 30 mil (0.76 mm) thick sheet formed of a
poly(ethylene-co-n-butyl acrylate) containing 30 wt % of
polymerized residues of n-butyl acrylate and having a MI of 2 g/10
min.
[0157] EVA is SC50B, believed to be a formulated composition based
on poly(ethylene-co-vinyl acetate) in the form of a 20 mil thick
(0.51 mm) sheet (Hi-Sheet Corporation, formerly Mitsui Chemicals
Fabro, Inc.).
[0158] Glass 1 is 2.5 mm thick float glass.
[0159] Glass 2 is a 2.5 mm thick clear annealed float glass plate
layer.
[0160] Glass 3 in a 3.0 mm thick Solex.RTM. solar control
glass.
[0161] PET 1 is a 7 mils (0.18 mm) thick poly(allyl amine)-primed,
biaxially-oriented poly(ethylene terephthalate) film layer.
[0162] PET 2 is a XIR.RTM.-70 HP Auto film (Southwall Company).
[0163] PET 3 is a XIR.RTM.-75 Auto Blue V-1 film (Southwall
Company).
[0164] PET 4 is a Soft Look.RTM. UV/IR 25 solar control film
(Tomoegawa Paper Company, Ltd., of Tokyo, Japan). [0165] PET 5 is a
XIR.RTM.-75 Green film (Southwall Company).
[0166] PET 6 is RAYBARRIER.RTM. TFK-2583 solar control film
(Sumitomo Osaka Cement Company).
[0167] PVB is B51V, believed to be a formulated composition based
on poly(vinyl butyral) in the form of a 20 mil thick (0.51 mm)
sheet (DuPont).
EXAMPLES 16-30
[0168] The 12.times.12 in (305.times.305 mm) laminate structures
described above in Table 1 are assembled and laminated by
Lamination Process 2, above.
EXAMPLES 31-43
[0169] The 12.times.12 in (305.times.305 mm) solar cell laminate
structures described below in Table 2 are assembled and laminated
by Lamination Process 1, above. Layers 1 and 2 constitute the
incident layer and front-sheet encapsulant layer, respectively, and
Layers 4 and 5 constitute the back-sheet encapsulant layer and the
backing layer, respectively.
TABLE-US-00002 TABLE 2 Solar Cell Laminate Structures Example Layer
1 Layer 2 Layer 3 Layer 4 Layer 5 31, 44 Glass 4 HMFAC 1 Solar Cell
1 HMFAC 1 FPF 32, 45 Glass 4 EVA Solar Cell 2 HMFAC 2 Glass 1 33,
46 Glass 4 HMFAC 3 Solar Cell 3 HMFAC 2 AL 34, 47 FPF HMFAC 4 Solar
Cell 1 HMFAC 4 FPF 35, 48 Glass 1 HMFAC 5 Solar Cell 2 HMFAC 5 PET
1 36, 49 Glass 4 HMFAC 7 Solar Cell 3 HMFAC 6 FPF 37, 50 FPF HMFAC
8 Solar Cell 3 HMFAC 8 FPF 38, 51 Glass 2 HMFAC 10 Solar Cell 4
HMFAC 9 Glass 2 39, 52 Glass 4 HMFAC 11 Solar Cell 1 HMFAC 11 FPF
40, 53 FPF HMFAC 12 Solar Cell 2 HMFAC 12 PET 1 41, 54 FPF HMFAC 13
Solar Cell 4 HMFAC 13 FPF 42, 55 Glass 4 HMFAC 14 Solar Cell 1
HMFAC 14 Glass 1 43, 56 Glass 4 HMFAC 15 Solar Cell 4 HMFAC 16
[0170] AL is a 3.2 mm thick aluminum sheet (3.2 mm thick) that is
5052 alloyed with 2.5 wt % of magnesium and conforms to Federal
specification QQ-A-250/8 and ASTM B209.
[0171] FPF is a 1.5 mil (0.038 mm) thick corona surface treated
Tedlar.RTM. film, DuPont.
[0172] Glass 4 is Starphire.RTM. glass from the PPG
Corporation.
[0173] Solar Cell 1 is a 10-inch by 10-inch amorphous silicon
photovoltaic device comprising a stainless steel substrate (125
micrometers thick) with an amorphous silicon semiconductor layer
(see, e.g., U.S. Pat. No. 6,093,581, Example 1).
[0174] Solar Cell 2 is a 10-inch by 10-inch copper indium
diselenide (CIS) photovoltaic device (see, e.g., U.S. Pat. No.
6,353,042, column 6, line 19).
[0175] Solar Cell 3 is a 10-inch by 10-inch cadmium telluride
(CdTe) photovoltaic device (see, e.g., U.S. Pat. No. 6,353,042,
column 6, line 49).
[0176] Solar Cell 4 is a silicon solar cell made from a 10-inch by
1-inch polycrystalline EFG-grown wafer (see, e.g., U.S. Pat. No.
6,660,930, column 7, line 61).
EXAMPLES 44-56
[0177] The 12.times.12 in (305.times.305 mm) solar cell laminate
structures described above in Table 2 are assembled and laminated
by Lamination Process 2, above. Layers 1 and 2; constitute the
incident layer and the front-sheet encapsulant layer, respectively,
and Layers 4 and 5 constitute the back-sheet encapsulant layer and
the backing layer, respectively.
COMPARATIVE EXAMPLE CE1 AND EXAMPLE 57
[0178] In Comparative Example CE1, 50 grams of a
poly(ethylene-co-methacrylic acid) copolymer containing 12 wt %
polymerized residues of methacrylic acid and having a MI of 3.3
g/10 min was added to a 90.degree. C. preheated Brabender Rheometer
(C. W. Brabender Instruments, Inc., So. Hackensack, N.J.) equipped
with a 50 cc mixing head over 1 minute, while the speed of the
mixing blades was set at 8 rpm. The process was shut down after
approximately 1/3 of the polymer resin had been added since the
resin was not melting or mixing with resin pellets flying out at
the top of the Brabender.
[0179] In Example 57, 50 grams of a poly(ethylene-co-methacrylic
acid) copolymer containing 19 wt % polymerized residues of
methacrylic acid and having a MI of 86 g/10 min was added to a
90.degree. C. preheated Brabender Rheometer equipped with a 50 cc
mixing head over 1 minute, while the speed of the mixing blades was
set at 8 rpm. The speed of mixing blades was then increased to 30
rpm and the polymer resin was further mixed for 5 minutes, after
which, a homogeneous polymer melt was achieved with the mixing
motor at 0.5 amp and the polymer melt temperature at 106.degree. C.
The process was shut down.
[0180] The results demonstrated that high flow acid copolymers
(Example 57) can be compounded at temperatures low enough (about
90.degree. C.) for the incorporation of organic peroxides through
commercially-viable and scalable extrusion compounding equipment
while corresponding low flow acid copolymers (Comparative Example
CE1) can not.
* * * * *