Process for forming a durable low emissivity moisture vapor permeable metallized sheet including a protective metal oxide layer

Abstract

A process for forming a low emissivity, moisture vapor permeable metallized composite sheet by coating a moisture vapor permeable sheet with at least one metal and exposing the freshly deposited metal to an oxidizing plasma thereby forming a protective synthetic metal oxide over the metal. The composite sheet material is suitable for use as a building construction barrier layer such as roof lining and house wrap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an apparatus suitable for forming a composite sheet of the present invention.

FIG. 2 is a graph of Electron Spectroscopy for Chemical Analysis (ESCA) spectra of the surfaces of a metallized high density polyethylene plexifilamentary film-fibril sheet having naturally formed aluminum oxide thereon, and two high density polyethylene plexifilamentary film-fibril sheets metallized and post-treated in vacuum with oxygen plasma, indicating the presence of both aluminum and aluminum oxide at a surface depth of 10 nm.

FIGS. 3A and 3B are graphs of ESCA spectra of the surfaces of a metallized UHDPE film having naturally formed aluminum oxide thereon, and two UHDPE films metallized and post-treated in vacuum with oxygen plasma, indicating the presence of both aluminum and aluminum oxide at surface depths of 5 nm (FIG. 3A) and 10 nm (FIG. 3B).

Claims

1. A process for forming a moisture vapor permeable metallized composite sheet comprising: placing a porous moisture vapor permeable sheet in a vacuum chamber and drawing a vacuum within said vacuum chamber;depositing a metal coating onto at least one surface of a porous moisture vapor permeable sheet so as to substantially cover the outer surfaces of the moisture vapor permeable sheet while leaving the pores thereof substantially uncovered; andoxidizing the surface of the metal coating with an oxygen-containing plasma within said vacuum chamber to form a synthetic metal oxide coating.

2. The process of claim 1 further comprising forming at least one organic coating on the synthetic metal oxide coating.

3. The process of claim 1 wherein the surface of the metal coating is exposed to the plasma for between about 5 milliseconds and about 5000 milliseconds.

4. The process of claim 3, wherein the plasma source has an alternating voltage of a frequency and power level sufficient to produce the synthetic metal oxide coating.

5. The process of claim 2 wherein the organic coating is selected from polymers, oligomers or combinations thereof.

6. The process of claim 1, further comprising forming at least one organic coating onto said porous moisture vapor permeable sheet prior to depositing said metal coating.

7. A moisture vapor permeable metallized composite sheet comprising a porous moisture vapor permeable sheet having first and second outer surfaces and at least one multilayer coating comprising: a metal coating having a thickness between about 15 nanometers and 200 nanometers deposited on the first outer surface of the porous moisture vapor permeable sheet;a synthetic metal oxide coating having a thickness of less than about 10 nm formed by oxidizing the metal coating with an oxygen-containing plasma; andan outer organic coating having a thickness between about 0.05 μm and about 1 μm deposited on the metal oxide coating;wherein the multilayer coating substantially covers the outer surface of the porous moisture vapor permeable sheet, while leaving the pores thereof substantially uncovered.

8. The moisture vapor permeable metallized composite sheet of claim 7, which has an emissivity of less than about 0.20.

9. The moisture vapor permeable metallized composite sheet of claim 7, wherein the metal is selected from the group consisting of aluminum, tin, zinc, silicon, scandium, titanium, vanadium, chromium, manganese, cobalt, nickel, yttrium, zirconium, niobium, molybdenum, indium and their alloys.

10. The moisture vapor permeable metallized composite sheet of claim 7, wherein the metal is aluminum and the synthetic metal oxide coating comprises aluminum oxide.

11. The moisture vapor permeable metallized composite sheet of claim 7, further comprising an intermediate organic coating between said porous moisture vapor permeable sheet and said metal coating.

12. The moisture vapor permeable metallized composite sheet of claim 7, wherein the organic coating is selected from polymers, oligomers and blends thereof.

13. The moisture vapor permeable metallized composite sheet of claim 12, which is liquid repellent.

14. The moisture vapor permeable metallized composite sheet of claim 12, which is corrosion resistant.

15. The moisture vapor permeable metallized composite sheet of claim 7, wherein said organic coating comprises a cross-linked polyacrylate or vinyl.

16. The moisture vapor permeable metallized composite sheet of claim 11, wherein said intermediate organic coating comprises a cross-linked polyacrylate or vinyl.

17. The moisture vapor permeable metallized composite sheet of claim 7, wherein said porous moisture vapor permeable sheet is selected from the group consisting of nonwoven fabrics, woven fabrics, microporous films, microperforated films, paper and composites thereof.

18. A construction barrier layer comprising: a porous moisture vapor permeable sheet selected from the group consisting of nonwoven fabrics, woven fabrics, microporous films, microperforated films and composites thereof, having first and second outer surfaces and at least one multilayer coating comprising:a metal coating having a thickness between about 15 nanometers and 200 nanometers deposited on the first outer surface of the moisture vapor permeable sheet;a synthetic metal oxide coating having a thickness of less than about 10 nm formed by oxidizing the metal layer with an oxygen-containing plasma; andan outer organic coating having a thickness between about 0.05 μm and about 1 μm deposited on the metal layer;wherein the multilayer coating substantially covers the outer surface of the moisture vapor permeable sheet while leaving the pores substantially uncovered.

19. The construction barrier layer of claim 18, wherein said organic coating is liquid repellant.

20. The construction barrier layer of claim 18, wherein said synthetic metal oxide coating comprises aluminum oxide.