ACRYLIC PHOTOVOLTAIC MODULE BACKSHEET

• US 20110315189A1
• Filed: 03/01/2010
• Published: 12/29/2011
• Est. Priority Date: 03/03/2009
• Status: Active Grant

• Current Assignee: Trinseo Europe Gmbh
• Original Assignee: Arkema France (Arkema)
• Inventors: Ge, Jiaxin Jason, Wanat, Robert A., Hu, Rong Maria, Aubart, Mark A.
• Granted Patent: US 10,640,672 B2
• Time in Patent Office: Days
• US Class Current: 136/244
• CPC Class Codes: B29C 65/00 Joining or sealing of preformed parts , e.g. welding of plastics materials; Apparatus therefor general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/919 characterised by specific temperature, heat or thermal flux values or ranges specific electrical resistance values B29C66/81262
• CPC Class Codes: B29C 66/91935 lower than said fusion temperature
• CPC Class Codes: B29C 66/91943 higher than said glass transition temperature
• CPC Class Codes: B29K 2027/16 PVDF, i.e. polyvinylidene fluoride
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 2307/206 Insulating
• CPC Class Codes: B32B 2307/4026 within the layer by addition of a colorant, e.g. pigments, dyes
• CPC Class Codes: B32B 2307/416 Reflective
• CPC Class Codes: B32B 2307/546 Flexural strength; Flexion stiffness
• CPC Class Codes: B32B 2307/558 Impact strength, toughness
• CPC Class Codes: B32B 2307/712 Weather resistant
• CPC Class Codes: B32B 2327/12 containing fluorine
• CPC Class Codes: B32B 2333/04 Polymers of esters
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2457/12 Photovoltaic modules
• CPC Class Codes: B32B 27/08 : of synthetic resin
• CPC Class Codes: B32B 27/16 : specially treated, e.g. irradiated
• CPC Class Codes: B32B 27/18 : characterised by the use of special additives
• CPC Class Codes: B32B 27/20 : using fillers, pigments, thixotroping agents
• CPC Class Codes: B32B 27/304 : comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• CPC Class Codes: B32B 27/306 : comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/308 : comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 : comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/322 : comprising halogenated polyolefins, e.g. PTFE
• CPC Class Codes: B32B 27/36 : comprising polyesters
• CPC Class Codes: B32B 7/12 : using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: C08L 2666/02 : Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/24 : Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 27/16 : Homopolymers or copolymers or vinylidene fluoride
• CPC Class Codes: C08L 51/00 : Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds for ABS polymers C08L55/02; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 53/00 : Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• CPC Class Codes: C09D 133/12 : Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: H01L 31/049 : Protective back sheets
• CPC Class Codes: Y02E 10/50 : Photovoltaic [PV] energy
• CPC Class Codes: Y10T 428/269 : including synthetic resin or polymer layer or component

Abstract

The invention relates to an acrylic layer (in the form of a coating, film or sheet) useful as part of a photovoltaic module backsheet. The acrylic layer contains at least 40 percent of one or more acrylic polymers, including an acrylic polymer matrix and optionally acrylic impact modifiers. The acrylic polymer is preferably a polymer, copolymer, or terpolymer containing at least 50 weight percent of methylmethacrylate monomer units. The acrylic layer is flexible and optionally contains high levels of white pigment. It may also contain fluoropolymers such as polyvinylidene fluoride to improve weathering, processibility and film formation. The acrylic layer adheres to a polymer support layer such as polyethylene terephthalate (PET). A preferred substrate is PET that is pre-treated to improve adhesion, but unprimed PET can also be used. The backsheet provides excellent weatherability, environmental stability and reflectivity as part of a photovoltaic module.

Claims

1. A multi-layer backsheet comprising an acrylic homopolymer or copolymer layer (the acrylic layer) adhered to a polymer support layer, wherein said acrylic layer comprises at least 40 percent by weight of one or more acrylic polymers, and wherein said acrylic layer is in the form of one or more coatings, films, or sheets having a total thickness of from 10 to 200 microns, and wherein said backsheet is useful as the backsheet of a photovoltaic module.

2. The backsheet of claim 1, wherein said acrylic layer has either a T_m of greater than 25°

C. if said layer is crystalline or semi-crystalline, or a Tg of greater than 10°

C. if said layer is amorphous.

3. The backsheet of claim 2, wherein said acrylic layer has either a T_m of greater than 70°

C. if said layer is crystalline or semi-crystalline, or a Tg of greater than 70°

C. if said layer is amorphous.

4. The backsheet of claim 3, wherein said acrylic layer has either a T_ff, of greater than 85°

C. if said layer is crystalline or semi-crystalline, or a Tg of greater than 85°

C. if said layer is amorphous.

5. The backsheet module of claim 1, wherein said acrylic layer further comprises from 5 to 50 weight percent of one or more pigments, based on the weight of the acrylic polymer.

6. The backsheet of claim 5, wherein said pigment(s) are white pigments.

7. The backsheet of claim 6, wherein said white pigment comprises TiO₂, ZnO, and BaSO₄ particles.

8. The backsheet of claim 1, wherein said acrylic polymer comprises an acrylic matrix and from 0 to 50 weight percent of one or more impact modifiers, based on the total weight of acrylic polymers.

9. The backsheet of claim 8, wherein said acrylic polymer comprises an acrylic matrix and from 10 to 30 weight percent of one or more acrylic impact modifiers, based on the total weight of acrylic polymers.

10. The backsheet of claim 1, wherein said acrylic polymer comprises from 0.01 to 20 weight percent of functionalized monomer units.

11. The backsheet of claim 10, wherein said functionalized monomer units comprise acrylic acid, methacrylic acid, or a mixture thereof.

12. The backsheet of claim 1, wherein said acrylic layer further comprises one or more fluoropolymers that are miscible, semi-miscible or compatible with said acrylic polymers, and wherein the ratio of said acrylic polymer(s) to said fluoropolymer is from 40:

60 to 100;

0.

13. The backsheet of claim 12, wherein said fluoropolymer comprises a homopolymer or copolymer of polyvinylidene fluoride, comprising at least 75 weight percent of vinylidene fluoride monomer units.

14. The backsheet of claim 12, wherein the ratio of said acrylic polymer(s) to said fluoropolymer is from 51:

49 to 95;

5.

15. The backsheet of claim 1, wherein said acrylic layer has a Tg of greater than 110°

C.

16. The backsheet of claim 1, wherein said polymer support layer is selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and functionalized polyolefins.

17. The backsheet of claim 1, further comprising one or more additional layers selected from the group consisting of an additional acrylic layer of the same or different composition, a fluoropolymer layer, an ethylene vinyl cetate (EVA) layer, and a thermoplastic layer.

18. The backsheet of claim 1 wherein said acrylic layer has either a Tm or Tg of greater than 85°

C., wherein said acrylic layer comprises at least 51 weight percent of acrylic polymer(s), wherein said acrylic polymer(s) comprise an acrylic polymer matrix having from 0.01 to 20 weight percent of functionalized monomer units, and wherein said acrylic layer comprises from 5 to 50 weight percent of one or more white pigment(s) based on the weight of the polymer(s).

19. The backsheet of claim 1, wherein said acrylic polymer layer further is crosslinkable, and reactive with multi-functional groups.

20. The backsheet of claim 1, wherein said acrylic layer further comprises reactive additives.

21. A photovoltaic module comprising, in order from front to back:

a) a solar radiation transparent glazing material;

b) one or more solar cells; and

c) the backsheet of claim 1.