United States Gypsum Company

Knauf Gips Kg

Mark K Hemphill

Qinghua Li

Yijun Sang

Suman Sinha Ray

James Wittbold

Charles W Cochran

Amit P Duvedi

Wayne A Fleming

Ashish Dubey

Michael Patrick Shake

Christopher J Nelson

Christopher Robert Nelson

Annamaria Vilinska

Runhai Lu

Naveen Punati

Naser Aldabaibeh

Te Hua Lau

James W Barber

Mark Antosh

Trevor S Rische

Kirk S Moore

Wilford Gary Pittman

Yongman Kim

Nicholas S Jones

Kevern O Fraser

Aaron D Johnson

Jon Cross

James R Wittbold

This disclosure provides products useful as construction materials and containing set gypsum and ammonium-exchanged vermiculite, including a gypsum panel having a gypsum core comprising set gypsum and ammonium-exchanged vermiculite and characterized by decreased heat shrinkage and increased resistance to fire damage in comparison to the gypsum panel that comprises vermiculite that has not been ammonium-exchanged. The disclosure further relates to methods for producing the gypsum panel and constructing building assemblies with the gypsum panels, including walls and ceilings.

Gypsum panel containing ammonium-exchanged vermiculite and methods

A fire-resistant gypsum panel comprises: a gypsum core layer comprising set gypsum and a high temperature sag-resistant material including mineral wool in an amount between 0.2% and 3.0% by weight of gypsum.

High temperature sag resistant gypsum panel

Disclosed is a composite gypsum board comprising a set gypsum core disposed between face (e.g., Manila) and back (e.g., Newsline) cover sheets. The set gypsum core is formed from a core slurry comprising stucco, water, and optional additives, such as foaming agent, migrating starch, accelerator, retarder, dispersant, etc. A dense layer formed from a dense layer slurry comprising stucco, water, fiber (e.g., paper fiber), and optionally, strength-enhancing starch, is disposed between the core and the face paper. The dense layer slurry contains a greater concentration of fiber, and optionally, strength-enhancing starch, than the core slurry, but the concentration of one or more other additives (e.g., accelerator, retarder, dispersant, or combinations thereof) is lower or the same in the dense slurry as compared with the core slurry. Also disclosed is a method of making board using one board mixer. In embodiments, paper fiber is added to water to form a suspension. The suspension is introduced, while in a non-laminar state, into the dense slurry. Further disclosed is apparatus, such as an extractor and an additive injection system, which can be a part of a cementitious slurry mixing and dispensing assembly.

Board with fiber-reinforced dense layer

An open cell set gypsum core includes an interlocking matrix of gypsum having air voids distributed therein. The air voids define cells having cell walls formed by the interlocking matrix. The interlocking matrix further includes channels distributed therein. The channels interconnect the air voids and comprise openings in the cell walls.

Open-celled gypsum core, gypsum acoustic panel, and method for making same

A gypsum wallboard having a core with a central core layer and one or more densified layers is disclosed. At least one densified layer contains salt absorbent particles of zeolite and/or hydrotalcite to improve adhesion of the gypsum core to a cover sheet. Also, methods of making the gypsum wallboard and a wall system for employing the gypsum wallboard are disclosed.

High salt gypsum wallboard containing salt absorbents and methods of making same

Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains set gypsum layers sandwiched between two cover sheets. The set gypsum layers are formed from at least stucco and water. The set gypsum layers include a board core and one or more skim coat layers. The set gypsum core makes up a substantial thickness (e.g., at least about 90%, at least about 92%, at least about 95%, or at least about 97%) of the total thickness of all the gypsum layers. A first skim coat layer is included on one side of the core, facing a first (face) cover sheet. A second skim coat layer is included on the other side of the core, facing a second (back) cover sheet. At least the second skim layer is formed from a slurry that contains starch. The stucco material generally includes a high salt impurity content, for example, when the stucco is calcined from certain sources of low-quality synthetic gypsum. For example, in some embodiments, the salts are chloride salts, e.g., sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl), and/or calcium chloride (CaCl).

Method of preparing gypsum wallboard from high salt gypsum, and related product

Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains at least one set gypsum layer sandwiched between two cover sheets. The set gypsum layer is formed from at least stucco and water. The stucco material generally includes a high salt impurity content, for example, when the stucco is calcined from certain sources of low-quality synthetic gypsum. For example, in some embodiments, the salts are chloride salts, e.g., sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl), and/or calcium chloride (CaCl)). At least one of the cover sheets is composed of high absorption paper, which enhances the bond between the set gypsum layer and the cover sheet.

Gypsum board containing high absorption paper and related methods

An accelerator for accelerating the rate of hydration of calcined gypsum is disclosed. The accelerator comprises calcium sulfate dihydrate particles and a starch. The starch has a cold water solubility of at least about 25% (e.g., at least about 35%) and a viscosity of about 25 Brabender Units (BU) or less when the starch is in a 30% aqueous slurry at 92&#xb0; C. Also disclosed are a method of preparing an accelerator, method of hydrating stucco to form set gypsum, slurry, and method of making gypsum board.

Accelerator comprising starch, and related board, slurries, and methods

Disclosed are a composite gypsum board and a method of preparing composite gypsum board. The board contains a set gypsum core sandwiched between two cover sheets. The core is formed from a slurry containing stucco, water, and optional ingredients such as foaming agent, accelerator, retarder, polyphosphate, starch, and dispersant, and core intumescent material. The board also contains at least one skim coat and/or hard edges. A face skim coat layer can be included on one side of the core, facing a face cover sheet. A back skim coat layer can be included on the other side of the core, facing a back cover sheet. Hard edges are known in the art and can be formed, e.g., continuously from a stucco slurry for forming the face and/or back skim coats. Preferably, the back skim coat layer and/or the hard edges are formed from a slurry containing stucco, water, skim coat or edge intumescent material (which have the same desired characteristics), and other optional additives as desired. The skim coat or edge intumescent material can be composed of the same material as the core intumescent material, if desired, but the skim coat and/or edge intumescent material is present in a higher relative concentration in its respective slurry than the amount of core intumescent material in the core slurry. Examples of suitable intumescent materials include expandable vermiculite (e.g., No. 4 or No. 5 according to the US naming system, or combinations thereof), expandable graphite, perlite, or any combination thereof.

Fire resistant gypsum board and related methods

Disclosed is an acid-modified flour and a method of making the acid-modified flour. The acid-modified flour is desirably prepared using a dry milling process. A starting flour is combined with a strong acid to form a mixture. The mixture is heated. A neutralizer is added to increase the pH of the mixture. If desired, the mixture can be dried and any agglomerates can be removed. The acid-modified flour can be used as a binder in a slurry for preparing one or more gypsum layers in a gypsum board.

Flour binder for gypsum board, and related methods, product, and slurries

Beads of materials such as activated alumina, zeolite and silica gel, are used as chloride salt absorbers. The beads are mixed with high-salt gypsum. After mixing for a short time, the mixtures are dried, and the beads and the powder are separated by using a sieve or other physical separation device resulting in a low-salt gypsum which can be used as a gypsum source to make gypsum wallboard.

Methods of removing chloride from gypsum having high level of chloride salt

Disclosed are an organic binder-based coating; a composite gypsum board containing face and back cover sheets, an outside surface of the back cover sheet bearing the coating; and a method of preparing composite board where the back cover sheet contains the coating on its outer surface. The coating is formed from a composition comprising an alkaline silicate, a solid filler, and optionally, a borate. An enhancing layer can also be applied to the back cover sheet.

Gypsum wallboard with enhanced fire resistance, and related coatings and methods

Gypsum boards formed from synthetic gypsum and other gypsum sources having high chloride salt concentrations. The gypsum boards may include a set gypsum board core layer between a front and back paper cover sheets. The back paper cover sheet has a plurality of perforations extending therethrough. Methods of making the gypsum boards, and a wall system for employing the gypsum boards, are also provided. The concentration of the chloride anion in aqueous gypsum slurry used to make the set gypsum board core layer and to perform the methods of the invention may range from about 500 ppm to about 3000 ppm, typically from about 500 ppm to about 2000 ppm per 1,000,000 parts by weight calcium sulfate hemihydrate, more typically from about 500 ppm to about 1500 ppm per 1,000,000 parts by weight calcium sulfate hemihydrate.

Gypsum board from gypsum having high level of chloride salt and a perforated sheet and methods associated therewith

Gypsum boards formed from synthetic gypsum and other gypsum sources having high chloride salt concentrations. Gypsum boards may include a board core including set gypsum. A total concentration of the chloride anion in the board core ranges from about 500 ppm to about 3000 ppm, typically about 1000 ppm to about 3000 ppm, based on weight of the calcium sulfate hemihydrate. An inner surface of a front paper cover sheet contacts a first face of the board core. An inner surface of a back paper cover sheet contacts a second face of the board core. A starch layer coats the inner surface of at least one of the front and back cover sheet. Methods of making the gypsum board, and a wall system for employing the gypsum boards, are also provided.

Gypsum board from gypsum having high level of chloride salt and a starch layer and methods associated therewith

Disclosed is a composite gypsum board comprising a board core comprising set gypsum sandwiched between face and back cover sheets. The composite gypsum board also comprises an intermediate sheet between the board core and the face cover sheet, with a thin, dense gypsum layer disposed between the intermediate sheet and the face cover sheet. Optionally, a second dense gypsum layer can be disposed between a first major side of the board core and the back cover sheet. Also disclosed is a method of preparing a composite gypsum board in which an intermediate sheet is applied over a dense gypsum layer disposed on a face cover sheet. A back cover sheet is applied to the other major side of the board core, with a second dense gypsum layer optionally disposed therebetween.

Growing community of inventors

Monroe, NY, United States of America

Mark K Hemphill