Paper having mineral filler for use in the production of gypsum wallboard
US4372814A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1981 |
| Grant date | Feb 8, 1983 |
| Priority date | — |
| Expiry date | May 13, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31996
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A composite paper particularly adapted for use as cover sheets in the production of gypsum wallboard, the paper being sufficiently porous to permit better drainage and more rapid drying in the production of the paper, and when applied to the surfaces of a gypsum slurry for forming wallboard, permits less heat to be utilized in the wallboard conversion, thereby saving energy in the board production required for drying the board. The paper comprises in weight percent: PA1 (A) fibers in an amount of from about 65% to about 90% and having a fiber freeness of from about 350 to 550 ml. Canadian Standard Freeness, PA1 (B) a mineral filler in an amount from about 10% to about 35%, PA1 (C) a binder in an amount from about 1% to about 31/2%, PA1 (D) a flocculant in an amount of from about 2 to about 4 lb./ton, and PA1 (E) a sizing agent in an effective amount to prevent water penetration. In an preferred embodiment the paper is treated with an internal sizing agent during its formation, and subsequently treated with a surface sizing agent after formation, in order to provide better adhesion to the gypsum core.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.