Light weight gypsum fiber panel suitable for use as roof cover board

Patent metadata

Field	Value
Publication number	US-9950957-B2
Application number	US-201615087539-A
Country	US
Kind code	B2
Filing date	Mar 31, 2016
Priority date	Oct 16, 2015
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A roof cover board made from a mixture of 30-60% stucco; 20-50% perlite; 10-30% cellulose fiber; 3-20% starch; and siloxane. Also disclosed is a stucco-free roof cover board made from a mixture of 30-60% perlite, 30-60% cellulose fiber, 5-25% starch; and siloxane. Also disclosed are methods for making same.

First claim

We claim:

1. A roof cover board made from a mixture of, on a water free basis, in wt. %:
30-45% stucco (calcium sulfate hemihydrate);
20-50% perlite;
15-30% cellulose fiber;
8-20% starch; and
0.2 to 2% siloxane.

2. The board of claim 1 , wherein the mixture comprises:
40-45% stucco;
20-35% perlite;
20-30% cellulose fiber;
8-15% starch; and
0.2 to 2% siloxane.

3. The board of claim 2 , wherein the perlite comprises particles of expanded perlite, wherein the cellulose fiber comprises recycled cellulose fiber, and wherein the starch is corn starch, wherein the recycled cellulose fiber comprises corrugated container board (OCC) or double lined kraft (DLK), and the expanded perlite has a density between 2 and 20 lbs/ft 3 , wherein the cellulose fibers have a weighted average fiber length of greater than 3.5 mm to at most 6 mm.

4. The board of claim 1 , wherein the board has an absence of bituminous material, wherein the mixture has 0.2 to 2% siloxane, wherein the stucco is the largest single component by dry weight, and wherein the board has 0 to 0.4 wt. % additional optional ingredients.

5. The board of claim 1 , wherein the mixture has 0.2 to 2% siloxane further comprising a catalyst selected from the group consisting of an alkaline earth oxide, an alkaline hydroxide, and any combination thereof, and the siloxane catalyst is present in a ratio of catalyst-to-siloxane of 0.5.

6. The board of claim 1 , wherein the mixture contains
40-45% stucco,
20-35% perlite,
20-30% cellulose fiber,
8-15% starch, and
0.4 to 1% siloxane.

7. The board of claim 1 , wherein the siloxane is methyl hydrogen siloxane, wherein the perlite comprises particles of expanded perlite, wherein the cellulose fiber comprises recycled cellulose fiber, and wherein the starch is corn starch.

8. The board of claim 1 , wherein the perlite comprises particles of expanded perlite, wherein the cellulose fiber comprises recycled cellulose fiber, and wherein the starch is corn starch, wherein the mixture comprises 40-45% stucco.

9. The board of claim 1 , wherein the board has a thickness of 0.25-1 inch, weight of 500-900 lbs/MSF, a density between 12 and 22 lbs/ft 3 , a MOR of at least 150 psi, and a compressive strength of at least 100 psi.

10. The board of claim 1 , wherein the board has an absence of newsprint and the cellulose fibers have a weighted average fiber length of greater than 1.4 mm.

11. A method of manufacturing the roof cover board of claim 1 , the method comprising:
mixing a composition containing:
stucco,
perlite,
cellulose fiber,
starch,
siloxane, and
water

to form a slurry furnish with a consistency of 5-15%,
the composition in wt. % on a water free basis being a mixture of:
30-45% stucco,
20-50% perlite,
15-30% cellulose fiber,
8-20% starch,
0.2 to 2% siloxane, and

depositing the slurry furnish onto a moving wire;
dewatering the slurry furnish to form a pad;
optionally, pressing the pad to further remove water and to achieve a desired thickness and surface smoothness;
cutting the pad to form uncured roof cover boards;
allowing the uncured boards to set; and
drying the set boards in a kiln.

12. A roof cover board made from a mixture of, on a water free basis, in wt. %:
30-60% perlite,
30-60% recycled cellulose fiber,
5-25% starch, and
0.2 to 2% siloxane;
having an absence of stucco,
having an absence of bituminous material,
having an absence of newsprint, and
containing less than 5% polymer; and
the board having a weight between 450 and 600 lbs/MSF and a density of between 11 and 14 lbs/ft 3 .

13. The board of claim 12 , wherein the recycled fiber is recycled cellulose fiber, and wherein the mixture contains
45-55% perlite,
35-45% recycled cellulose fiber,
8-12% starch, and
0.2 to 2% siloxane.

14. The board of claim 12 , wherein the perlite comprises particles of expanded perlite and wherein the starch is corn starch.

15. The board of claim 14 , wherein the recycled cellulose fiber comprises corrugated container board (OCC) or double lined kraft (DLK), and the expanded perlite has a density between 2 and 20 lbs/ft 3 .

16. The board of claim 12 , further comprising a catalyst, wherein the siloxane is methyl hydrogen siloxane for use as a water repellant and the catalyst is magnesium oxide.

17. The board of claim 12 , having a thickness of 0.25-1 inch, having a MOR of at least 150 psi, and a compressive strength of at least 90 psi.

18. The board of claim 12 , wherein the recycled cellulose fibers have a weighted average fiber length of greater than 1.4 mm.

19. A method of manufacturing the roof cover board, using a wet forming process comprising:
mixing a composition containing:
perlite,
recycled cellulose fiber,
starch,
siloxane, and
water

to form a furnish with a consistency of 3-10%;
the composition in wt. % on a water free basis being a mixture of:
30-60% perlite,
30-60% recycled cellulose fiber,
5-25% starch, and
0.2 to 2% siloxane,
having an absence of stucco,
having an absence of bituminous material,
having an absence of newsprint, and
containing less than 5% polymer;

dewatering the furnish on a moving wire to form a pad;
optionally, pressing the pad to further remove water and achieve desired thickness and surface smoothness,
cutting the pad to form green board; and
drying the green board in a kiln, the dried board having a weight between 400 and 685 lbs/MSF, and a density of between 10 and 17 lbs/ft 3 .

20. A roof cover board made from a mixture of, on a water free basis, in wt. %:
45-55% perlite,
35-45% recycled cellulose fiber,
8-12% starch, and
0.2 to 2% siloxane;
having an absence of stucco,
having an absence of bituminous material,
having an absence of newsprint, and
containing less than 5% polymer; and
the board having a weight between 400 and 685 lbs/MSF and a density of between 10 and 17 lbs/ft 3 .

Assignees

• United States Gypsum Co

Inventors

• Xu Yufeng
• Stivender Eugene S

Classifications

• C04B28/145

  Calcium sulfate hemi-hydrate with a specific crystal form · CPC title

• C04B18/24

  Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper {, cork} · CPC title

• C04B2111/00612

  as one or more layers of a layered structure · CPC title

• C04B14/185

  expanded · CPC title

• E04C2/02

  characterised by specified materials (translucent E04C2/54) · CPC title