Photocell assembly

• US 4,636,578 A
• Filed: 04/11/1985
• Issued: 01/13/1987
• Est. Priority Date: 04/11/1985
• Status: Expired due to Fees

• Current Assignee: Atlantic Richfield Company (BP PLC)
• Original Assignee: Atlantic Richfield Company (BP PLC)
• Inventors: Feinberg, Stewart C.
• Primary Examiner(s): Weisstuch, Aaron
• Application Number:
  US06/722,085
• Time in Patent Office: 642 Days
• Field of Search: 136/251, 136/259, 29/588, 357/72
• US Class Current: 136/251
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10743 containing acrylate (co)polymers or salts thereof
• CPC Class Codes: H01L 31/0481 characterised by the composition of the encapsulation material
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

Photocell modules wherein one or more photocells are encapsulated within a thermoplastic polymeric pottant between the layers of a rigid or flexible laminate. The pottant is a graft copolymer of (a) at least one addition polymerizable backbone monomer having a glass transition temperature (T_g) of less than 0°, (b) at least one addition polymerizable backbone monomer having a T_g of 50°-150° C., and (c) a poly (vinyl aromatic) addition polymerizable macromonomer of 3,000-50,000 molecular weight having a T_g of at least 30° C. The pottant is highly light-transmissive, electrically insulating and provides excellent protection for the photocells and circuitry at low cost.

Claims

1. A photocell assembly comprising first and second sheets in spaced apart, laminar arrangement, said first sheet being transparent and light transmissive, said sheets defining a cavity therebetween, said cavity containing one or more photocells encapsulated within a thermoplastic polymeric pottant comprising a graft copolymer of

(a) 50-90 wt. %, based on graft copolymer, of at least one addition polymerizable backbone monomer having a T_g of less than 0°

C.,

(b) 0-10 wt. %, based on graft copolymer, of at least one addition polymerizable backbone monomer having a T_g of 50°

-150°

C., and

(c) 10-50 wt. %, based on graft copolymer, of a macromonomer comprising poly (vinyl aromatic) of number average molecular weight of 3,000-50,000 and having an addition polymerizable end group, said macromonomer having a T_g of at least 30°

C.

2. The photocell assembly of claim 1 wherein the macromonomer (c) comprises poly(vinyl aromatic) capped with alkylene oxide or alkylene sulfide and terminated with an alpha, beta monoethylenically unsaturated compound.

3. The photocell assembly of claim 1 wherein the T_g of backbone monomer (a) is less than -40°

C., the T_g of backbone monomer (b) is 80°

-120°

C., and the T_g of graft macromonomer (c) is at least 80°

C.

4. The photoceil assembly of claim 1 wherein the backbone monomer component (a) comprises at least one alkyl (C₁ -C₁₀) acrylate, backbone monomer component (b) comprises at least one monomer selected from acrylic acid, methacrylic acid, acrylamide or methacrylamide, and macromonomer (c) comprises polystyrene or poly (alpha-methylstyrene), capped with ethylene oxide and terminated with acryloyl halide or methacryloyl halide.

5. The photocell assembly of claim 4 wherein the T_g of backbone monomer (a) is less than -40°

C., the T_g of backbone monomer (b) is 80°

-120°

C., and the T_g of macromonomer (c) is at least 80°

C.

6. The photocell assembly of claim 5 wherein the backbone monomer component (a) comprises n-butyl acrylate, 2-ethylhexyl acrylate or a mixture thereof, backbone monomer (b) is acrylic acid, and macromonomer (c) is polystyrene capped with ethylene oxide and terminated with methacryloyl chloride.

7. The photocell assembly of claim 6 wherein the number average molecular weight of macromonomer (c) is about 10,000-35,000 and the number average molecular weight of the graft copolymer is about 100,000-200,000.

8. The photocell assembly of claim 6 wherein backbone monomer (a) comprises 60-80 wt. % of the graft copolymer, backbone monomer (b) comprises 0-5 wt. % of the graft copolymer, and macromonomer (c) comprises 20-40 wt. % of the graft copolymer.

9. The photocell assembly of claim 1 wherein said polymeric pottant is in the form of two sheets hot melted together on opposing sides of the photocell.

10. The photocell assembly of claim 1 wherein the second sheet comprises a metal layer and the assembly includes an electrical insulating sheet between said metal layer and the pottant material.

11. The photocell assembly of claim 1 wherein the pottant is in the form of a hot melt adhesive and the photocell is embedded in said adhesive.