Fire-resistant gypsum board and method for making same

Abstract

The present disclosure generally relates to a method for producing a fire-resistant gypsum board including a gypsum core, the method including: providing a calcium sulfate slurry including a silicone oil having a Si-H hydride content of 0.01 equivalents of silicon or less per equivalent of silicon in an amount of 0.5 to 1.5 weight percent based on the mass of the gypsum core; setting the calcium sulfate slurry; and drying the set gypsum material to provide a gypsum core. The present disclosure also relates to a fire-resistant gypsum board including a gypsum core that shrinks less than 6 volume percent when heated to 850°C, the gypsum core including a silicone oil having a Si-H hydride content of 0.01 equivalents of silicon or less per equivalent of silicon, present in an amount ranging from 0.05 to 1.5 weight percent based on the mass of the gypsum core.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 384059, filed November 16, 2022, and European Patent Application Publication No. 23152888.6, filed January 23, 2023, each of which is incorporated by reference in its entirety.

[0002] FIELD OF THE INVENTION FIELD OF THE DISCLOSURE The present disclosure relates generally to fire-resistant gypsum boards and methods for making same. [Background technology]

[0003] Gypsum building products (e.g., variously known as wallboard, ceiling board, plasterboard, and "drywall") are panels made of a gypsum core sandwiched between two liner layers, often paper, on the exterior surfaces of the gypsum core. They are widely used as building materials due to their ease of manufacture, high mechanical strength, low thermal conductivity, resistance to fire spread, and soundproofing properties. The quality of gypsum board depends heavily on its gypsum core, which is processed into a hardened calcium sulfate dihydrate body by hydration of a stucco slurry (containing primarily calcium sulfate hemihydrate). To control the properties of gypsum board, additives are often added to the stucco slurry during the board manufacturing process. For example, foaming agents, inorganic compounds, and other additives may be included in the slurry to adjust the density, strength, and / or fire resistance properties of the board.

[0004] To provide fire-resistant gypsum boards, it has been common to incorporate a small amount of polymethylhydrosiloxane (PMHS) to improve the fire resistance properties of the board. By including PMHS, the gypsum board exhibits reduced board shrinkage at high temperatures, which indicates improved structural integrity. However, due to a global shortage, PMHS has become a cost-prohibitive additive. Therefore, there is a need in the art to find alternative additives that provide similar fire resistance performance and to find ways to better distribute the additive throughout the gypsum board. Summary of the Invention

[0005] In one aspect, the present disclosure provides a method of making a fire resistant gypsum board comprising a gypsum core, the method comprising: providing a calcium sulfate slurry containing a silicone oil having a hydride content of 0.01 equivalents of Si-H or less per equivalent of silicon in an amount of 0.05 to 1.5 wt. % (e.g., 0.1 to 1.0 wt. %) of the mass of the gypsum core; setting the calcium sulfate slurry to form a set gypsum material; and drying the set gypsum material to provide a gypsum core.

[0006] The silicone oil can be provided to the calcium sulfate slurry using, for example, an aqueous emulsion of silicone oil. As an alternative, when high shear mixing is used to mix the calcium sulfate slurry, the silicone oil can be emulsified in the high shear mixing.

[0007] In another aspect, the present disclosure provides a fire resistant gypsum board made by the methods described herein.

[0008] In another aspect, the disclosure provides a fire-resistant gypsum board (e.g., made by a method described herein) comprising a gypsum core that shrinks less than 6% by volume when heated to 850°C, wherein the gypsum core comprises a silicone oil having a hydride content of 0.01 or less equivalents of Si—H per silicon equivalent, present in an amount ranging from 0.05 to 1.5 wt. % (e.g., 0.1 to 1.0 wt. %) based on the weight of the gypsum core. [Brief explanation of the drawings]

[0009] The accompanying drawings are included to provide a further understanding of the methods of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings are not necessarily to scale, and sizes of various elements may be distorted for clarity. The drawings illustrate one or more embodiments of the present disclosure and, together with the description, serve to explain the principles and operation of the present disclosure. [Figure 1] FIG. 1 is a diagram of a fire resistant board as described herein. [Figure 2] 1 is a graph of the diameter reduction rate of fire gypsum tested according to ASTM C1795. [Figure 3] 1 is a graph of the diameter reduction rate of fire-rated gypsum board tested according to ASTM C1795. [Figure 4] 1 is a graph of diameter reduction for fire rated gypsum boards tested according to ASTM C1795 and made by the methods described herein. [Figure 5] 1 is a graph of diameter reduction for fire rated gypsum boards tested according to ASTM C1795 and made by the methods described herein. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present inventors have developed a method for producing a fire resistant board that does not require the use of polymethylhydrosiloxane (PMHS) yet still has the desired fire resistant properties.

[0011] As mentioned above, PMHS is often used to provide fire resistance to gypsum board. However, due to the shortage of silicone oil, the use of PMHS in gypsum board is becoming more expensive. Therefore, there is a need in the art to find an acceptable substitute for PMHS that provides the same fire resistance to gypsum board.

[0012] Additionally, the inventors have noticed that PMHS tends to migrate to the surface of the gypsum board during the curing and drying of the board. This tendency of PMHS to migrate to the surface of the board can leave a relatively small amount of PMHS in the center of the board, thus making the center of the board less fire-resistant. To address this drawback of PMHS in fire-resistant boards, the inventors have found a way to provide a fire-resistant gypsum board that improves thermal performance and better distributes silicone oil inside the gypsum board.

[0013] The present disclosure relates to fire-resistant gypsum boards containing a gypsum core and methods for making them. Accordingly, in one aspect, the present disclosure provides a method for making a fire-resistant gypsum board containing a gypsum core, comprising: a calcium sulfate slurry containing a silicone oil having a Si-H hydride content of 0.01 equivalents or less per silicon equivalent in an amount of 0.05 to 1.5 weight percent of the mass of the gypsum core; setting the calcium sulfate slurry to form a hardened gypsum material; and drying the hardened gypsum material to provide a gypsum core. In another aspect, the present disclosure also provides a fire-resistant gypsum board (e.g., made by a method described herein) containing a gypsum core that shrinks less than 6 volume percent when heated to 850°C, wherein the gypsum core contains a silicone oil having a Si-H hydride content of 0.01 equivalents or less per silicon equivalent, present in an amount ranging from 0.05 to 1.5 weight percent based on the weight of the gypsum core. The present inventors have determined that the use of polydimethylsiloxane is a good choice of silicone oil in the methods and systems of the present disclosure.

[0014] As will be understood by those skilled in the art, silicone oils can include a variety of different polysiloxanes. Such polysiloxanes can contain both hydrogen groups and other functional groups to modify the polysiloxane backbone. For example, PMHS contains both Si-H bonds and Si-CH3 bonds. The silicone oils of the emulsions described herein have a Si-H hydride content of 0.01 equivalents or less per equivalent of silicon (i.e., silicon atom). Thus, the silicone oils described herein have a low hydride content, for example, substantially no hydride content. In various embodiments, the silicone oils have a Si-H hydride content of 0.005 equivalents or less, or 0.002 equivalents or less, or 0.001 equivalents or less per equivalent of silicon. As will be understood by those skilled in the art, equivalents are calculated as molar equivalents.

[0015] Various silicones can be used in the methods and boards of the present disclosure. In some embodiments of the present disclosure described herein, the silicone oil comprises an alkyl-functional silicone. As used herein, an alkyl-functional silicone is a polysiloxane functionalized with an alkyl group. For example, in some embodiments, the silicone oil comprises a methyl-functional silicone, an ethyl-functional silicone, a propyl-functional silicone, or a butyl-functional silicone. In some embodiments, the silicone oil is a polydimethylsiloxane. However, in some embodiments, the silicone oil may be, for example, a copolymer of dimethylsiloxane with methylsiloxane or phenylsiloxane (in an amount such that the hydride content remains low). However, in many embodiments, it is desirable that the molar content of dimethylsiloxane units in the silicone oil is at least 90%, for example, at least 95% or at least 99%.

[0016] As described above, the silicone oil can be provided to the calcium sulfate slurry using, for example, an aqueous emulsion of silicone oil. In some embodiments, the aqueous emulsion of silicone oil can be provided by emulsifying silicone oil in water. The aqueous emulsion of silicone oil can be prepared by any emulsification process known in the art. In some embodiments, emulsification is achieved by a mechanical process. For example, in some embodiments, the aqueous emulsion of silicone oil is emulsified by mixing, shaking, and / or vortexing water with the silicone oil. The inventors have found that the emulsification process does not require any additional additives (e.g., emulsifiers) to provide an emulsified silicone. The emulsification may be carried out for a certain time, at a certain mixer speed, and at a certain temperature; such parameters are not particularly limited. It may be desirable to introduce the emulsion into the calcium sulfate slurry immediately after emulsification, without allowing time for the emulsion to significantly deteriorate. In some embodiments, the silicone oil emulsion can have a silicone oil concentration of, for example, 10 to 70% silicone oil.

[0017] Of course, other methods can also be used. For example, in some embodiments, the silicone oil can be provided to the calcium sulfate by mixing the silicone oil into the calcium sulfate slurry under conditions sufficient to form an emulsion. The mixing conditions of the calcium sulfate slurry itself can be sufficient to provide the desired silicone oil emulsion, for example, when high shear mixing is used. Thus, the high shear mixer used to mix the calcium sulfate slurry itself can emulsify the silicone in the slurry. In other embodiments, the silicone can be emulsified in the water used to make the calcium sulfate slurry.

[0018] In some embodiments, the silicone oil has a d50 droplet size in the range of 5 to 100 microns, which can be, for example, the d50 droplet size of the silicone oil emulsion added to the calcium sulfate slurry and / or the d50 droplet size of the silicone oil in the calcium sulfate slurry itself.

[0019] As mentioned above, the inventors speculate that the use of an emulsion helps limit the migration of silicone oil in the gypsum core, so that the silicone oil concentration can remain more uniform throughout. Accordingly, in some embodiments of the methods and boards described herein, the silicone oil concentration in the center of the gypsum core is at least 50% of the concentration within 10% of the outer edge of the gypsum core. For example, in various embodiments, the silicone oil concentration in the center of the gypsum core is at least 60%, or at least 65%, or at least 70%, or at least 75% of the concentration within 10% of the outer edge of the gypsum core. In some embodiments, the silicone oil concentration in the center of the gypsum core is at least 50% of the concentration at the edge of the gypsum core. In various embodiments, the silicone oil concentration in the center of the gypsum core is at least 60%, or at least 65%, or at least 70%, or at least 75% of the concentration at the edge of the gypsum core. In this regard, "center" and "edge" refer to locations measured along the thickness axis of the board. The "center" of the core is indicated by dashed line 120 in FIG. 1, and the "outer edge" of the core is indicated by arrow 125 in FIG. 1, which is described in more detail below.

[0020] As described above, the methods described herein include combining to provide a calcium sulfate slurry. In some embodiments, the calcium sulfate slurry is formed by combining stucco with water. As known in the art, stucco can have a variety of compositions depending on the source at hand and the application. As used herein, "stucco" is a material having at least 75% by weight calcium sulfate hemihydrate. It is typically provided by calcining gypsum to convert the dihydrate to hemihydrate. Real-world samples of stucco typically contain one or more of calcium sulfate dihydrate, calcium sulfate anhydrite, and inert calcium sulfate, along with the hemihydrate (e.g., present as α-calcium sulfate hemihydrate, β-calcium sulfate hemihydrate, or a combination thereof).

[0021] As described above, the calcium sulfate slurry includes stucco and water. As one skilled in the art will appreciate, the water provides fluidity to the slurry for ease of handling while also providing the water necessary for hydration to hemihydrate gypsum. One skilled in the art will select the desired ratio of stucco to water. In various embodiments of the present disclosure, the weight ratio of stucco to water in the slurry is 3:1 or less, e.g., 5:2 or less, or 2:1 or less, or 7:4 or less, or 3:2 or less. For example, in various embodiments, the weight ratio of stucco to water ranges from 3:1 to 1:2, or 2:1 to 4:7, or 3:1 to 2:3, or 3:1 to 1:1, or 5:2 to 1:2, or 5:2 to 4:7, or 5:2 to 2:3, or 5:2 to 1:1, or 2:1 to 1:2, or 2:1 to 4:7, or 2:1 to 2:3, or 2:1 to 1:1, or 7:4 to 1:2, or 7:4 to 4:7, or 7:4 to 2:3, or 7:1 to 1:1, or 3:2 to 1:2, or 3:2 to 4:7, or 3:2 to 2:3, or 3:2 to 1:1. Stucco is desirably present in the calcium sulfate slurry to provide a board having a gypsum core comprising primarily gypsum. For example, in various embodiments, the gypsum core comprises at least 75% gypsum, or at least 80% gypsum by weight, or at least 85% gypsum by weight.

[0022] As described above, the silicone oil (optionally emulsified) is present in the calcium sulfate slurry in an amount of 0.05 to 1.5 weight percent of the gypsum core mass. For example, in various embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.05 to 1.3 weight percent, or from 0.05 to 1.2 weight percent of the gypsum core mass. In various embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.05 to 1 weight percent, e.g., from 0.05 to 0.85 weight percent, or from 0.05 to 0.75 weight percent, or from 0.05 to 0.6 weight percent of the gypsum core mass. In various embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.05 to 0.5 weight percent, e.g., from 0.05 to 0.4 weight percent, or from 0.05 to 0.3 weight percent, or from 0.05 to 0.25 weight percent of the gypsum core mass. In various embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 1.5 wt. % of the gypsum core mass, e.g., from 0.1 to 1.3 wt. %, or from 0.1 to 1.2 wt. % of the gypsum core mass. In various embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 1 wt. % of the gypsum core mass, e.g., from 0.1 to 0.85 wt. %, or from 0.1 to 0.75 wt. %, or from 0.1 to 0.6 wt. % of the gypsum core mass. In various embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 0.5 wt. % of the gypsum core mass, e.g., from 0.1 to 0.4 wt. %, or from 0.1 to 0.3 wt. %, or from 0.1 to 0.25 wt. % of the gypsum core mass. In some embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 1.5 weight percent of the gypsum core mass, e.g., from 0.25 to 1.3 weight percent, or from 0.25 to 1.2 weight percent of the gypsum core mass. For example, in various embodiments described herein, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 1 weight percent of the gypsum core mass, e.g., from 0.25 to 0.85 weight percent, or from 0.25 to 0.75 weight percent, or from 0.25 to 0.65 weight percent. In some embodiments, the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 0.5 weight percent, e.g., from 0.25 to 0.4 weight percent of the gypsum core mass. The inventors have discovered that significant improvements in fire performance can be achieved at low concentrations of silicone.

[0023] Although not described in detail herein, one or more additives can be provided in the calcium sulfate slurry. For example, in some embodiments, the additive is selected from one or more accelerators, superplasticizers, retarders, dispersants, foaming agents, and / or glass fibers. In some embodiments, the additive is present in an amount of 10% or less by weight of the calcium sulfate mass in the slurry. In various embodiments, the additive is present in the slurry in an amount of 8% or less by weight or 5% or less by weight of the gypsum core mass. Similarly, in some embodiments, the additive is present in the gypsum core of the board in an amount of 10% or less by weight of the gypsum core mass, e.g., 8% or less by weight or 5% or less by weight. One skilled in the art would use an appropriate set of additives for a desired gypsum core material.

[0024] Thus, in various desirable embodiments, the slurry contains at least 85% by weight, e.g., at least 90% by weight, calcium sulfate on a dry weight basis (i.e., excluding absorbed water, but including water of hydration). Similarly, in various desirable embodiments, the gypsum core of the gypsum board contains at least 85% by weight, e.g., at least 90% by weight, calcium sulfate (i.e., including all hydrated and anhydrous forms thereof) based on the mass of the gypsum core.

[0025] In various embodiments, the slurry contains 5% or less by weight calcium carbonate, based on the amount of stucco in the slurry, i.e., in addition to any calcium carbonate provided as part of the stucco component. For example, in various embodiments, the slurry contains 3% or less, 2% or less, 1% or less, or 0.5% or less by weight calcium carbonate, based on the amount of stucco in the slurry, i.e., in addition to any calcium carbonate provided as part of the stucco component.

[0026] In various embodiments, the slurry contains 5% or less by weight each of potassium phosphates (including hydrogen phosphates and dihydrogen phosphates) and magnesium oxide, based on the amount of stucco in the slurry. For example, in various embodiments, the slurry contains 3%, 2%, 1%, or 0.5% or less by weight each of potassium phosphates (including hydrogen phosphates and dihydrogen phosphates) and magnesium oxide, based on the amount of stucco in the slurry.

[0027] In various embodiments, the gypsum core of the gypsum board contains 3% or less by weight each of struvite-K and syngenite based on the weight of the gypsum core. For example, in various embodiments, the gypsum core of the gypsum board contains 2% or less by weight each of struvite-K and syngenite based on the weight of the gypsum core, e.g., 1% or less by weight or less, or 0.5% or less by weight each of struvite-K and syngenite.

[0028] The method also includes setting the calcium sulfate slurry to form a set gypsum material. As one skilled in the art will appreciate, the calcium sulfate slurry described herein sets over time to form a set gypsum material. Accelerators or retarders in the slurry can be used to adjust the set time. One skilled in the art can use a conventional board production line to form the set gypsum material between the liners to create a building board.

[0029] As described above, the method includes drying the set gypsum material to provide a gypsum core. In some embodiments, drying is performed at a temperature in the range of 50-350°C or 50-300°C (i.e., as measured in the environment above the board during drying, e.g., in a drying oven) to provide a gypsum core. For example, in various embodiments, drying is performed at a temperature in the range of 100-350°C, or 100-325°C, or 100-300°C, or 150-350°C, or 150-325°C, or 150-300°C, or 200-350°C, or 200-325°C, or 200-300°C. Drying may be accomplished using an oven, with oven temperatures ranging from 50 to 350°C, or 50 to 325°C, or 50 to 300°C, or 100 to 350°C, or 100 to 325°C, or 100 to 300°C, or 150 to 350°C, or 150 to 325°C, or 150 to 300°C, or 200 to 350°C, or 200 to 325°C, or 200 to 300°C. During the drying step, the temperature of the gypsum core desirably does not exceed 125°C, e.g., 120°C, 115°C, 110°C, or 105°C. Those skilled in the art can use conventional drying methods when practicing the methods and boards of the present disclosure.

[0030] As mentioned above, the use of silicones as described herein, for example, providing the silicone as an emulsion, can provide gypsum boards with good fire resistance. One way to measure the fire resistance properties of a board is to measure the amount of shrinkage the board undergoes when exposed to high temperatures. Such measurements are performed as described in ASTM C1795, which can be used to measure high temperature shrinkage at 850°C. Lower shrinkage indicates better fire resistance. In some embodiments, the gypsum core shrinks less than 6% (e.g., less than 5%, or less than 4%) when heated to 850°C as measured by ASTM C1795.

[0031] Another aspect of the present disclosure provides fire-resistant gypsum boards made by the methods described herein. Even if the boards made by the methods described herein do not meet all of the board limitations described in more detail below, the parameters described herein may be useful for many of the specific methods described above.

[0032] Another aspect of the present disclosure provides a fire-resistant gypsum board (e.g., made by a method described herein) including a gypsum core that shrinks less than 6% by volume when heated to 850°C, wherein the gypsum core comprises a silicone oil having a hydride content of 0.01 equivalents of Si-H per equivalent of silicon or less, present in an amount ranging from 0.05 to 1.5% by weight based on the weight of the gypsum core.

[0033] As mentioned above, evaluation of the fire resistance of gypsum boards can be accomplished by measuring the shrinkage of the boards at elevated temperatures. In some embodiments, the fire resistant gypsum boards described herein shrink less than 5% by volume (e.g., less than 4% by volume) when heated to 850°C.

[0034] The silicone oil can be as described in any embodiment above with respect to the method of making gypsum board of the present disclosure. In various embodiments described herein, the silicone oil is an alkyl-functional polydimethylsiloxane.

[0035] In some embodiments, the gypsum core of the fire-rated gypsum board described herein comprises silicone oil in an amount ranging from 0.05 to 1.5 wt.%, e.g., 0.05 to 1.3 wt.%, or 0.05 to 1.2 wt.%, based on the weight of the gypsum core. In some embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.05 to 1.0 wt.%, e.g., 0.05 to 0.85 wt.%, or 0.05 to 0.75 wt.%, or 0.05 to 0.65 wt.%, based on the weight of the gypsum core. In various embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.05 to 0.5 wt.%, e.g., 0.05 to 0.4 wt.%, or 0.05 to 0.3 wt.%, or 0.05 to 0.25 wt.%, based on the weight of the gypsum core. In some embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.1 to 1.5 wt.%, e.g., 0.1 to 1.3 wt.%, or 0.1 to 1.2 wt.%, based on the weight of the gypsum core. In some embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.1 to 1.0 wt.%, e.g., 0.1 to 0.85 wt.%, or 0.1 to 0.75 wt.%, or 0.1 to 0.65 wt.%, based on the weight of the gypsum core. In various embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.1 to 0.5 wt.%, e.g., 0.1 to 0.4 wt.%, or 0.1 to 0.3 wt.%, or 0.1 to 0.25 wt.%, based on the weight of the gypsum core. In some embodiments, the gypsum core of the fire-rated gypsum board described herein comprises silicone oil in an amount ranging from 0.25 to 1.5 wt.%, e.g., 0.25 to 1.3 wt.%, or 0.25 to 1.2 wt.%, based on the weight of the gypsum core. In various embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.25 to 1.0 wt.%, e.g., 0.25 to 0.85 wt.%, or 0.25 to 0.75 wt.%, or 0.25 to 0.65 wt.%, based on the weight of the gypsum core. In various embodiments, the gypsum core comprises silicone oil in an amount ranging from 0.25 to 0.5 wt.%, e.g., 0.25 to 4 wt.%, based on the weight of the gypsum core.

[0036] As will be understood by those skilled in the art, gypsum boards typically include liners on opposing major surfaces. In some embodiments of the present disclosure described herein, the gypsum core of a fire-resistant gypsum board is disposed between a first liner on a first major surface of the gypsum board and a second liner on a second, opposing major surface of the board. An example of such a gypsum board is shown in the cross-sectional schematic diagram of FIG. 1, where a fire-resistant gypsum board (100) includes a gypsum core (101) and a first liner (102) on a first major surface (112) of the gypsum board, and a second liner (104) on a second, opposing major surface (114) of the gypsum board. The liner may be formed, for example, from paper (which itself may be coated with various substances, e.g., wax or silicone) or fiberglass. Of course, other liner materials are possible. [Example]

[0037] The following examples illustrate specific embodiments of the disclosed methods and products, and various uses thereof. They are provided for illustrative purposes only and should not be construed as limiting the scope of the disclosure.

[0038] Example 1. Effect of PDMS concentration on high-temperature shrinkage without emulsification Gypsum boards were prepared with different polydimethylsiloxane (PDMS) concentrations. To prepare the boards, a gypsum slurry containing 550 g of stucco, 284.08 g of water, 2 g (5.79 lbs / msf, 0.4 wt. % based on the weight of the stucco) of accelerator, 5 g (14.48 lbs / msf, 1 wt. % based on the weight of the stucco) of plaster retarder, and 1 wt. % surfactant based on the weight of the stucco was prepared. PDMS was added to the slurry in various amounts. The PDMS was not emulsified before being added to the slurry. For comparison, a gypsum slurry without silicone oil was prepared.

[0039] The gypsum slurry was then allowed to set and then dried to form board samples. Each board was 5 / 8 inch thick. The samples were prepared and tested for high temperature shrinkage at 850°C per ASTM C1795 to evaluate the fire resistance properties of the boards. Table 1 reports the board formulations and the results of the high temperature shrinkage tests. Figure 2 also shows the ASTM C1795 high temperature shrinkage at 850°C results, including error bars. The error bars for ASTM C1795 high temperature shrinkage at 850°C for these measurements are approximately 0.35%.

[0040] [Table 1]

[0041] The results in Table 1 and Figure 2 show that the inclusion of PDMS reduces the shrinkage rate of the board, which correlates with improved fire performance. Additionally, increasing the concentration of PDMS reduces shrinkage, which continues to decrease even after 2 lbs / msf.

[0042] For further comparison, board samples were prepared as above, but using 1.98 lbs / msf, 3.97 lbs / msf, and 5.9 lbs / msf polymethylhydrosiloxane (PMHS). Figure 3 shows the ASTM C1795 high temperature shrinkage results (including error bars) at 850°C for PMHS boards and PDMS boards. From Figure 3, it can be seen that PDMS and PMHS have similar effects on plasterboard shrinkage at the same concentrations. However, the effect of increasing the concentration of PMHS appears to plateau after 2 lbs / msf.

[0043] Example 2. Effect of PDMS emulsification on high-temperature shrinkage The gypsum board was prepared as described in Example 1, except that the PDMS was first emulsified before being added to the gypsum slurry. To emulsify the silicone oil, it was mixed in a VMI Rayneri (VMI Linxis Group: B00181347) equipped with an emulsifying blade. The emulsifying blade uses a 30 mm high stator with 29 slots and a rotor containing four blades. Emulsification was performed by mixing room temperature water and silicone oil at 2750 rpm for 2 minutes, after which the remainder of the liquid portion of the formulation was added, followed by the dry portion.

[0044] The boards were then tested by ASTM C1795 High Temperature Shrinkage at 850°C to evaluate the fire resistance properties of the boards. Table 2 reports the board formulations and the results of the high temperature shrinkage tests. Figure 4 also shows the ASTM C1795 High Temperature Shrinkage at 850°C results, including error bars. The error bars for ASTM C1795 High Temperature Shrinkage at 850°C in these measurements are approximately 0.35%.

[0045] [Table 2]

[0046] From the results in Table 2 and FIG. 4, it can be seen that by using emulsified PDMS, the diameter reduction rate of the board samples further decreases from −4.21% (Board No. 8) to −3.65% (Board No. 9).

[0047] Board samples were prepared as described above, except that 0.25 wt. % polymethylhydrosiloxane (PMHS) was used relative to the stucco. Figure 5 shows the ASTM C1795 high temperature shrinkage results (including error bars) at 850°C for PMHS and PDMS boards. Figure 5 shows that emulsification of PDMS provided improved shrinkage performance that was not observed with the PMHS board.

[0048] Various aspects and embodiments of the present disclosure are described by the following numbered embodiments, which may be combined in any number and in any combination not technically or logically consistent.

[0049] Embodiment 1. A method for making a fire-resistant gypsum board comprising a gypsum core, comprising: providing a calcium sulfate slurry containing a silicone oil having a hydride content of 0.01 equivalents of Si-H per equivalent of silicon or less in an amount of 0.05 to 1.5 weight percent of the mass of stucco used to form the slurry; setting the calcium sulfate slurry to form a set gypsum material; and drying the set gypsum material to provide a gypsum core.

[0050] Embodiment 2. The method of embodiment 1, wherein the silicone oil is an alkyl-functional silicone.

[0051] Embodiment 3. The method of embodiment 1 or 2, wherein the silicone oil is polydimethylsiloxane.

[0052] Embodiment 4. The method of any one of embodiments 1-3, wherein the silicone oil is provided to the calcium sulfate slurry in the form of an aqueous emulsion.

[0053] Embodiment 5. The method of any one of embodiments 1-3, wherein the silicone oil is provided to the calcium sulfate by mixing the silicone oil into the calcium sulfate slurry under conditions sufficient to form an emulsion.

[0054] Embodiment 6. The method of embodiment 4, wherein the aqueous emulsion of silicone oil has a d50 droplet size in the range of 5 to 100 microns.

[0055] Embodiment 7. The method of any one of embodiments 1 to 6, wherein the d50 droplet size of the silicone oil in the calcium sulfate slurry ranges from 5 to 100 microns.

[0056] Embodiment 8. The method of any of embodiments 1-7, wherein the silicone oil concentration in the center of the gypsum core is at least 50% of the concentration within 10% of the outer edge of the gypsum core.

[0057] Embodiment 9. The method of any of embodiments 1-7, wherein the silicone oil concentration in the center of the gypsum core is at least 60%, e.g., at least 65%, or at least 70%, or at least 75%, of the concentration within 10% of the outer edge of the gypsum core.

[0058] Embodiment 10. The method of any one of embodiments 1-7, wherein the silicone oil concentration at the center of the gypsum core is at least 50% of the concentration at the edge of the gypsum core.

[0059] Embodiment 11. The method of any of embodiments 1-7, wherein the silicone oil concentration at the center of the gypsum core is at least 60%, e.g., at least 65%, or at least 70%, or at least 75% of the concentration at the edge of the gypsum core.

[0060] Embodiment 12. The method of any one of embodiments 1-11, wherein the calcium sulfate slurry is formed by combining stucco and water in a weight ratio of 3:1 or less.

[0061] Embodiment 13. The method of any one of embodiments 1-11, wherein the calcium sulfate slurry is formed by combining stucco and water in a weight ratio ranging from 3:1 to 1:2.

[0062] Embodiment 14. The method of any one of embodiments 1-13, wherein the gypsum core comprises at least 75% by weight gypsum, e.g., at least 80% by weight gypsum, or at least 85% by weight gypsum.

[0063] Embodiment 15. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.05 to 1.3 wt. %, or from 0.05 to 1.2 wt. %, based on the mass of the gypsum core.

[0064] Embodiment 16. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.05 to 1.0 wt. %, e.g., 0.05 to 0.85 wt. %, or 0.05 to 0.75 wt. %, or 0.05 to 0.65 wt. %, based on the mass of the gypsum core.

[0065] Embodiment 17. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.05 to 0.5 wt.%, e.g., 0.05 to 0.4 wt.%, or 0.05 to 0.3 wt.%, or 0.05 to 0.25 wt.%, based on the mass of the gypsum core.

[0066] Embodiment 18. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 1.5 wt. %, e.g., 0.1 to 1.3 wt. %, or 0.1 to 1.2 wt. %, based on the mass of the gypsum core.

[0067] Embodiment 19. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 1.0 wt.%, e.g., 0.1 to 0.85 wt.%, or 0.1 to 0.75 wt.%, or 0.1 to 0.65 wt.%, based on the mass of the gypsum core.

[0068] Embodiment 20. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 0.5 wt.%, e.g., 0.1 to 0.4 wt.%, or 0.1 to 0.3 wt.%, or 0.1 to 0.25 wt.%, based on the mass of the gypsum core.

[0069] Embodiment 21. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 1.5 wt. %, e.g., 0.25 to 1.3 wt. %, or 0.25 to 1.2 wt. %, based on the mass of the gypsum core.

[0070] Embodiment 22. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 1.0 wt.%, e.g., 0.25 to 0.85 wt.%, or 0.25 to 0.75 wt.%, or 0.25 to 0.65 wt.%, based on the mass of the gypsum core.

[0071] Embodiment 23. The method of any one of embodiments 1 to 14, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 0.5 wt. %, e.g., 0.25 to 4 wt. %, based on the mass of the gypsum core.

[0072] Embodiment 24. The method of any one of embodiments 1 to 23, wherein one or more additives are provided in the calcium sulfate slurry.

[0073] Embodiment 25. The method of embodiment 24, wherein the additives are selected from one or more accelerators, flow agents, retarders, dispersants, foaming agents, and / or glass fibers.

[0074] Embodiment 26. The method of embodiment 24 or 25, wherein the additive is present in the slurry in an amount of 10% by weight or less (e.g., 8% by weight or less, or 5% by weight or less) of the mass of the gypsum core.

[0075] Embodiment 27. The method of any one of embodiments 1 to 26, wherein the slurry comprises at least 85% by weight, e.g., at least 90% calcium sulfate on a dry weight basis (i.e., excluding adsorbed water but including water of hydration).

[0076] Embodiment 28. The method of any one of embodiments 1-27, wherein the slurry contains 5% or less by weight of calcium carbonate relative to the amount of stucco in the slurry, i.e., in addition to any calcium carbonate provided as part of the stucco component.

[0077] Embodiment 29. The method of any of embodiments 1-27, wherein the slurry contains 3% by weight or less, e.g., 2% by weight or less, 1% by weight or less, or 0.5% by weight or less, of calcium carbonate, based on the amount of stucco in the slurry, i.e., in addition to any calcium carbonate provided as part of the stucco component.

[0078] Embodiment 30. The method of any one of embodiments 1-29, wherein the slurry contains 5% by weight or less of each of potassium phosphates (including hydrogen phosphates and dihydrogen phosphates) and magnesium oxide, based on the amount of stucco in the slurry.

[0079] Embodiment 31. The method of any one of embodiments 1-29, wherein the slurry contains 3% by weight or less, e.g., 2% by weight or less, 1% by weight or less, or 0.5% by weight or less, of each of potassium phosphates (including hydrogen phosphates and dihydrogen phosphates) and magnesium oxide, based on the amount of stucco in the slurry.

[0080] Embodiment 32. The method of any one of embodiments 1 to 31, wherein drying is carried out at a temperature in the range of 50 to 350°C to provide a gypsum core.

[0081] Embodiment 33. The method of any one of embodiments 1-32, wherein the gypsum core shrinks by less than 6% (e.g., less than 5%, or less than 4%) when heated to 850°C as measured by ASTM C1795.

[0082] Embodiment 34. A fire-resistant gypsum board produced by the method according to any one of embodiments 1 to 33.

[0083] Embodiment 35. A fire-rated gypsum board (e.g., made by the method of any of embodiments 1-33) comprising a gypsum core that shrinks less than 6% by volume when heated to 850°C, wherein the gypsum core comprises a silicone oil having a hydride content of 0.01 equivalents of Si-H per equivalent of silicon or less, present in an amount ranging from 0.05 to 1% by weight based on the mass of the gypsum core.

[0084] Embodiment 36. The fire-resistant gypsum board of embodiment 35, wherein the gypsum core shrinks by less than 5% by volume (e.g., less than 4% by volume) when heated to 850°C.

[0085] Embodiment 37. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.05 to 1.3 wt. %, or 0.05 to 1.2 wt. %, based on the mass of the gypsum core.

[0086] Embodiment 38. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.05 to 1.0 wt.%, e.g., 0.05 to 0.85 wt.%, or 0.05 to 0.75 wt.%, or 0.05 to 0.65 wt.%, based on the mass of the gypsum core.

[0087] Embodiment 39. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.05 to 0.5% by weight, e.g., 0.05 to 0.4% by weight, or 0.05 to 0.3% by weight, or 0.05 to 0.25% by weight, based on the mass of the gypsum core.

[0088] Embodiment 40. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.1 to 1.5 wt.%, e.g., 0.1 to 1.3 wt.%, or 0.1 to 1.2 wt.%, based on the mass of the gypsum core.

[0089] Embodiment 41. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.1 to 1.0 wt.%, e.g., from 0.1 to 0.85 wt.%, or from 0.1 to 0.75 wt.%, or from 0.1 to 0.65 wt.%, based on the mass of the gypsum core.

[0090] Embodiment 42. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.1 to 0.5% by weight, e.g., from 0.1 to 0.4% by weight, or from 0.1 to 0.3% by weight, or from 0.1 to 0.25% by weight, based on the mass of the gypsum core.

[0091] Embodiment 43. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.25 to 1.5 wt.%, e.g., 0.25 to 1.3 wt.%, or 0.25 to 1.2 wt.%, based on the mass of the gypsum core.

[0092] Embodiment 44. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.25 to 1.0 wt.%, e.g., 0.25 to 0.85 wt.%, or 0.25 to 0.75 wt.%, or 0.25 to 0.65 wt.%, based on the mass of the gypsum core.

[0093] Embodiment 45. The fire-resistant gypsum board of embodiment 35 or 36, wherein the gypsum core comprises silicone oil in an amount ranging from 0.25 to 0.5% by weight, for example, from 0.25 to 4% by weight, based on the mass of the gypsum core.

[0094] Embodiment 46. A fire-resistant gypsum board according to any one of embodiments 35 to 45, wherein the silicone oil is polydimethylsiloxane.

[0095] Embodiment 47. A fire-resistant gypsum board according to any one of embodiments 35-46, wherein the silicone oil concentration in the center of the gypsum core is at least 50% of the concentration within 10% of the outer edge of the gypsum core.

[0096] Embodiment 48. The fire-resistant gypsum board of any of embodiments 35-46, wherein the silicone oil concentration in the center of the gypsum core is at least 60%, e.g., at least 65%, or at least 70%, or at least 75%, of the concentration within 10% of the outer edge of the gypsum core.

[0097] Embodiment 49. A fire-resistant gypsum board according to any one of embodiments 35 to 46, wherein the silicone oil concentration at the center of the gypsum core is at least 50% of the concentration at the edge of the gypsum core.

[0098] Embodiment 50. The fire-resistant gypsum board of any of embodiments 35-46, wherein the silicone oil concentration at the center of the gypsum core is at least 60%, e.g., at least 65%, or at least 70%, or at least 75% of the concentration at the edge of the gypsum core.

[0099] Embodiment 51. The fire-resistant gypsum board of any of embodiments 35-50, wherein the additive is present in the gypsum core in an amount of 10% by weight or less (e.g., 8% by weight or less, or 5% by weight or less) of the mass of the gypsum core.

[0100] Embodiment 52. The fire-resistant gypsum board of any of embodiments 35-51, wherein the gypsum core contains at least 85% by weight, e.g., at least 90% by weight, calcium sulfate (i.e., including all hydrates and anhydrides thereof) based on the mass of the gypsum core.

[0101] Embodiment 53. A fire-resistant gypsum board according to any one of embodiments 35 to 50, wherein the gypsum core contains 3% by weight or less each of struvite-K and syngenite, based on the mass of the gypsum core.

[0102] Embodiment 54. The fire-resistant gypsum board of any one of embodiments 35 to 50, wherein the gypsum core contains 2% by weight or less, e.g., 1% by weight or less, or 0.5% by weight or less, each of struvite-K and syngenite, based on the mass of the gypsum core.

[0103] Embodiment 55. A fire-resistant gypsum board according to any of embodiments 35-54, wherein the gypsum core is disposed between a first liner on a first major surface of the gypsum board and a second liner on a second, opposing major surface of the board.

[0104] Embodiment 56. The fire-resistant gypsum board of embodiment 55, wherein the liner is a paper liner.

[0105] The details set forth herein are presented by way of example only for purposes of illustrative description of preferred embodiments of the present invention, and to provide what is believed to be the most useful and readily understood explanation of the principles and conceptual aspects of various embodiments of the present invention. In this regard, no attempt has been made to show structural details of the present invention in more detail than necessary for a fundamental understanding of the invention; the description, taken together with the figures and / or examples, will make apparent to those skilled in the art how several forms of the present invention may be embodied in practice. Therefore, before the disclosed processes and devices are described, it should be understood that the aspects described herein are not limited to specific embodiments, apparatus, or configurations, which may, of course, vary. It should also be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting unless specifically defined herein.

[0106] As used in the context of describing the present invention (particularly in the context of the claims that follow), the terms "a," "an," "the," and similar referents should be construed to cover both the singular and the plural unless otherwise indicated herein or clearly contradicted by context. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each separate value is incorporated herein as if it were individually recited herein. It is further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0107] All methods described herein can be performed in any suitable order of steps unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided herein, or the use of exemplary language (e.g., "etc."), are intended merely to better elucidate the invention and do not impose limitations on the scope of the invention as otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0108] Unless the context clearly dictates otherwise, throughout this specification and the claims, words like "comprise," "comprising," and the like, are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is, meaning "including, but not limited to." Words using the singular or plural also include the plural and singular, respectively. Additionally, the words "herein," "above," and "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application.

[0109] As will be understood by those skilled in the art, each embodiment disclosed herein can comprise, consist essentially of, or consist of its specified recited elements, steps, ingredients, or components. As used herein, the transitional phrases "comprise" or "comprises" mean "including," but are not limited to, and allow for the inclusion of even large amounts of unspecified elements, steps, ingredients, or components. The transitional phrase "consisting of" excludes any unspecified element, step, ingredient, or component. The transitional phrase "consisting essentially of" limits the scope of the embodiment to the specified elements, steps, ingredients, or components and to those that do not materially affect the embodiment.

[0110] Unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the scope of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0111] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0112] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limiting. Members of each group may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to include the modified group, and thus fulfills the written description of all Markush groups used in the appended claims.

[0113] Several embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or clearly contradicted by context.

[0114] It is further to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, and not of limitation, alternative configurations of the invention may be utilized in accordance with the teachings herein. Accordingly, the invention is not limited to that precisely as shown and described.

Claims

1. 1. A method for making a fire-resistant gypsum board comprising a gypsum core, the method comprising: providing a calcium sulfate slurry containing a silicone oil having a hydride content of 0.01 equivalents of Si—H per equivalent of silicon or less in an amount of 0.05 to 1.5 weight percent of the mass of stucco used to form the slurry; setting the calcium sulfate slurry to form a set gypsum material; and drying the set gypsum material to provide the gypsum core.

2. 10. The method of claim 1, wherein the silicone oil is an alkyl-functional silicone.

3. 3. The method of claim 1, wherein the silicone oil is polydimethylsiloxane.

4. 4. The method according to any one of claims 1 to 3, wherein the silicone oil is provided to the calcium sulfate slurry in the form of an aqueous emulsion.

5. 4. The method of claim 1, wherein the silicone oil is provided to the calcium sulfate by mixing the silicone oil into the calcium sulfate slurry under conditions sufficient to form an emulsion.

6. 6. The method of any one of claims 1 to 5, wherein the d50 droplet size of the silicone oil in the calcium sulfate slurry is in the range of 5 to 100 microns.

7. 7. The method of any one of claims 1 to 6, wherein the silicone oil concentration in the center of the gypsum core is at least 60% of the concentration within 10% of the outer edge of the gypsum core.

8. 8. The method of any one of claims 1 to 7, wherein the calcium sulfate slurry is formed by combining stucco and water in a weight ratio ranging from 3:1 to 1:

2.

9. 9. The method of claim 1, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.1 to 0.1 weight percent of the mass of the gypsum core.

10. 9. The method of any one of claims 1 to 8, wherein the silicone oil is present in the calcium sulfate slurry in an amount ranging from 0.25 to 0.75 weight percent of the mass of the gypsum core.

11. 11. The method of any one of claims 1 to 10, wherein the slurry contains no more than 1% by weight of calcium carbonate relative to the amount of stucco in the slurry, i.e., in addition to any calcium carbonate provided as part of the stucco component.

12. 12. The method of any one of claims 1-11, wherein the gypsum core shrinks less than 5% when heated to 850°C as measured by ASTM C1795.

13. A fire-resistant gypsum board (e.g., made by the method of any one of claims 1 to 12) including a gypsum core that shrinks less than 6% by volume when heated to 850°C, wherein the gypsum core includes a silicone oil having a hydride content of 0.01 equivalents of Si—H per equivalent of silicon or less, present in an amount ranging from 0.05 to 1.5% by weight based on the mass of the gypsum core.

14. 14. The fire resistant gypsum board of claim 13, wherein the gypsum core shrinks less than 5% by volume when heated to 850°C.

15. The fire-resistant gypsum board according to claim 13 or 14, wherein the gypsum core contains the silicone oil in an amount ranging from 0.1 to 1% by weight based on the weight of the gypsum core.

16. The fire-resistant gypsum board according to claim 13 or 14, wherein the gypsum core contains the silicone oil in an amount ranging from 0.25 to 0.75% by weight based on the weight of the gypsum core.

17. The fire-resistant gypsum board according to any one of claims 13 to 16, wherein the silicone oil is polydimethylsiloxane.

18. 18. The fire resistant gypsum board of any one of claims 13-17, wherein the gypsum core is disposed between a first paper liner on a first major surface of the gypsum board and a second paper liner on a second, opposing major surface of the board.

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