Patent Publication Number: US-2013251986-A1

Title: Building Material Containing Latent Heat Storage Material and Methods of Making the Same

Description:
BACKGROUND 
     The present disclosure generally relates to building material products comprising latent heat storage materials, and more particularly, to gypsum boards comprising phase change materials and methods of making the same. 
     There is a general desire in all technical fields to be energy efficient. In the building industry, for example, there is a permanent need to decrease the energy costs related to heating and cooling indoor rooms. A reduction in energy consumption can also have the added benefit of reducing carbon dioxide emissions. Recently, governmental bodies world-wide are considering setting caps on the amount of carbon dioxide emissions, which is creating a demand for more energy efficient buildings and building materials. 
     Accordingly, a continual need exists for improved building materials that aid in providing energy efficiency to buildings. 
     BRIEF SUMMARY 
     Disclosed herein are building materials, namely gypsum boards containing a latent heat storage material, and methods of making the same. 
     In one embodiment, a gypsum board comprises a gypsum core; and a facing material comprising a first side and second side opposite the first side, the second side is bonded to the gypsum core, wherein in an area proximate to the bond a latent heat storage material is disposed with a remainder of the gypsum core being substantially free of latent heat storage material. 
     In a second embodiment, a gypsum board comprises a gypsum core having a main portion and a second portion, the second portion being more dense than the main portion, wherein the second portion comprises a latent heat storage material; and a facing material comprising a first side and second side opposite the first side, the second side is bonded to the second portion of the gypsum core. 
     In a third embodiment, a gypsum board comprises a gypsum core; a facing material comprising a first side and second side opposite the first side, the second side is bonded to the gypsum core; a layer of encapsulated latent storage material disposed on the first side; and a coating layer disposed over the layer of encapsulated latent storage material such that substantially no encapsulated latent heat storage material is exposed to an outer surface of the coating layer. 
     In a fourth embodiment, a gypsum board comprises a gypsum core; a facing material comprising a first side and second side opposite the first side, the second side is bonded to the second portion of the gypsum core; and a coating layer disposed on the second side, wherein the coating comprises capsules of latent heat storage material. 
     In a fifth embodiment, a gypsum board comprises a gypsum core; a facing material comprising a first side and second side opposite the first side, the second side is bonded to the second portion of the gypsum core; and a coating layer disposed on the second side, wherein the coating comprises capsules of latent heat storage material. 
     In a sixth embodiment, a gypsum board comprises a gypsum core; a first fiber mat comprising a first side and second side opposite the first side, the second side is bonded to the second portion of the gypsum core; a first coating penetrating the first fiber mat from the first side into the fiber mat; a second fiber mat comprising a first side and second side opposite the first side, the second side is bonded to the gypsum core; a second coating penetrating the second fiber mat from the first side into the fiber mat; wherein both the first fiber mat and the second fiber mat each comprise glass fibers nominally about 10 to 16 microns in diameter and about one-quarter (¼) to about one (1) inch in length, the first fiber mat in the absence of coating has a basis weight of 1 to 3 pounds per 100 square feet; and wherein at least one of the first coating and the second coating each comprise a capsules of latent heat storage material and an organic binder. 
     In one embodiment, a method of making a gypsum board comprises: depositing a gypsum slurry for forming a set gypsum core onto a non-coated side of a pre-coated fiber mat, the fiber mat having a coating on a side opposite the non-coated side, the coating comprising an organic binder and a latent heat storage material; and drying the gypsum slurry to form a set gypsum core. 
     In a second embodiment, a method of making a gypsum board comprises: depositing a gypsum slurry for forming a set gypsum core onto a facing material; drying the gypsum slurry to form a set gypsum core; applying a latent heat storage material on the facing material on a side opposite in contact with set gypsum core; and applying a coating over the latent heat storage material. 
     In one embodiment, a building material comprises a paneled article having a first side and a second side; a layer of encapsulated latent heat storage material disposed on the first side; and a coating disposed over the layer of encapsulated latent heat storage material. 
     The above described and other features are exemplified by the following Figures and detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the exemplary drawings wherein like elements are numbered alike in the several Figures: 
         FIG. 1  is a cross-sectional view of an exemplary gypsum board comprising a phase change material in coating; 
         FIG. 2  is a cross-sectional view of an exemplary gypsum board comprising a phase change material disposed in a layer of the core of gypsum board; 
         FIG. 3  is a cross-sectional view of an exemplary gypsum board comprising a phase change material disposed on facing material with a coating disposed over the phase change material; and 
         FIG. 4  is shows a highly schematic view of an apparatus for making gypsum board. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is building materials containing latent heat storage materials and methods of making the same. Examples of building materials include, but are not limited to, gypsum board, wafer board, particle board, oriented strand board (OSB), plywood, fiberboard, medium density fiberboard (MDF), oriented strand lumber (OSL) parallel strand lumber (PSL), laminated veneer lumber (LVL), laminated strand lumber (LSL), cement board, wood, wood veneer, wood-plastic composites, plastic, plastic-cement composites, and combinations comprising at least one of the foregoing. 
     In one embodiment, the building material comprises a paneled article having a first side and a second side; a layer of encapsulated latent heat storage material disposed on the first side; and a coating disposed over the layer of encapsulated latent heat storage material. For ease in discussion, reference is hereinafter made to a gypsum board as an example of a building material for ease in discussion with the understanding that this disclosure can be adopted by a person of skill in the art to other building materials. 
     The term “latent heat storage” material is defined herein as a substance that has a phase transition temperature within a temperature range within which heat-transfer is intended. These materials are sometimes also referred to as phase change materials (PCMs). The PCMs disclosed herein have a solid/liquid phase transition in the temperature range from −20° C. (degrees Celsius) to 120° C. 
     Without wanting be bound by theory, it is believed that the location of the PCM in gypsum board can improve efficiency of heat transfer, thereby allowing less PCM material to be employed compared to, for example, homogenously distributing PCM in a gypsum core. More particularly, it is believed that the closer the PCM is to the surface of the gypsum board the more efficient the heat transfer will be. Embodiments are hereinafter described that have a stratified structure having a layer comprising a PCM. 
     Referring now to  FIG. 1 , an exemplary embodiment of a gypsum board  10  is shown. The gypsum board  10  comprises a board core  12  faced with a first facing material  14  and a second facing material  16 . The facing material  14  and  16  may be the same or different. For example, both facing material  14  and  16  may comprise glass fibers, both may comprise paper, or one may comprise paper and the other glass fibers. Other materials are envisioned for the facing materials  14  and  16  and are not a critical aspect of the invention. In one embodiment, both facing materials  14  and  16  comprise glass fibers nominally about 10 to 16 microns in diameter and about one-quarter (¼) to about one (1) inch in length, the first fiber mat in the absence of coating has a basis weight of 1 to 3 pounds per 100 square feet. 
     The board core  12  is basically of the type used in gypsum structural products commonly known as gypsum wallboard, dry wall, gypsum board, gypsum lath and gypsum sheathing. The core of such a product is formed by mixing water with powdered anhydrous calcium sulfate or calcium sulfate hemi-hydrate (CaSO 4 .½H 2 O), also known as calcined gypsum, to form an aqueous gypsum slurry, and thereafter allowing the slurry mixture to hydrate or set into calcium sulfate dihydrate (CaSO 4 .2H 2 O), a relatively hard material. The invention is not limited to any particular content of gypsum in the core. 
     A coating layer  18  is disposed on the first facing material  14 . An optional coating layer  22  can be disposed on facing material  16 . The coating material employed in coating layer  18  and  20  can be the same or different. In one embodiment, the coating layer  18  comprises a plurality of capsules  20  containing PCM. The capsules containing PCM are disposed within the coating such that substantially no capsules containing PCM is exposed to an outer surface of the coating layer  18 . The term “substantially” free or substantially none is being used throughout this disclosure to mean less than 10% by weight, based on a total weight (as defined by context, e.g., weight of coating), specifically less than 5% by weight. 
     The coating material used in coating layer  18  is selected to be compatible with the encapsulation material of PCM capsules  20  and the desired application. For example, if the coating layer  18  is disposed on the facing material  14  to form a pre-coated facing material, the porosity of the coating is controlled to allow water to evaporate thru the coating layer  18 . In “post” coating operations, porosity of the coating is less important. The term “post coating” is being used herein to refer to a coating operation after the gypsum board has been formed and dried in a drier. One potential advantage of post coating is less energy can be consumed compared to drying a gypsum board containing PCM, since the PCM absorbs heat energy. 
     Embodiments are envisioned where the coating layer comprises an organic binder, an inorganic binder or combinations of organic and inorganic binders. The choice of binder will vary depending on application and method employed in making the gypsum board  10 . 
     In one embodiment, the coating material used in the coating layer  18  comprises an organic binder. Examples of organic binders include, but are not limited to, styrene-butadiene-rubber (SBR), styrene-butadiene-styrene (SBS), ethylene-vinyl-chloride (EVCl), poly-vinylidene-chloride (PVdC), modified poly-vinyl-chloride (PVC), poly-vinyl-alcohol (PVOH), ethylene-vinyl-acetate (EVA), and poly-vinyl-acetate (PVA). Asphalt is not generally used as a binder in making a coated mat useful in this invention. 
     The coating layer  18  can optionally comprise a filler material. Examples of filler materials include, but are not limited to, ground limestone (calcium carbonate), sand, mica, talc, gypsum (calcium sulfate dihydrate), aluminum trihydrate (ATH), antimony oxide, or a combination of any two or more of these substances. 
     The PCM capsules  20  can be microcapsules, microcapsules, or a combination of the foregoing. The capsules comprise a capsule core of latent heat storage material and capsule wall of polymeric material, wherein about 90% or greater of the total weight of the capsule is the latent heat storage material. The term “microcapsule” is being used throughout this disclosure refers to capsules having a mean diameter of 1 to 100 μm (micrometers). The term “macrocapsule” is being used throughout this disclosure referred to any capsules having a mean diameter greater than 100 μm. The choice of capsule size will be variable dependent on desired application (e.g. fire rating). 
     Example of PCM materials and methods of making are discussed in U.S. Pat. No. 7,166,355 and include, but are not limited to: 1) aliphatic hydrocarbon compounds such as saturated or unsaturated C 10 -C 40 -hydrocarbons which are branched or specifically linear, e.g. n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-docosane, n-tricosane, n-tetracosane, n-pentacosane, n-hexacosane, n-heptacosane, n-octacosane, and cyclic hydrocarbons, e.g. cyclohexane, cyclooctane, cyclodecane; 2) aromatic hydrocarbon compounds such as benzene, naphthalene, biphenyl, o- or n-terphenyl, C 1 -C 40 -alkyl-substituted aromatic hydrocarbons such as dodecylbenzene, tetradecylbenzene, hexadecylbenzene, hexylnaphthalene or decylnaphthalene; 3) saturated or unsaturated C 6 -C 30 -fatty acids such as lauric, stearic, oleic or behenic acid, specifically eutectic mixtures of decanoic acid with, for example, myristic, palmitic or lauric acid; 4) fatty alcohols such as lauryl, stearyl, oleyl, myristyl and cetyl alcohols, mixtures such as coconut fatty alcohol and the oxo alcohols obtained by hydroformylation of α-olefins and further reactions; C 6 -C 30 -fatty amines such as decylamine, dodecylamine, tetradecylamine or hexadecylamine; 5) esters such as C 1 -C 10 -alkyl esters of fatty acids, e.g. propyl palmitate, methyl stearate or methyl palmitate, and specifically their eutectic mixtures or methyl cinnamate; 6) natural and synthetic waxes such as montanic acid waxes, montanic ester waxes, carnauba wax, polyethylene wax, oxidized waxes, polyvinyl ether wax, ethylene-vinyl acetate wax or hard waxes from Fischer-Tropsch processes; 7) halogenated hydrocarbons such as chloroparaffin, bromooctadecane, bromopentadecane, bromononadecane, bromoeicosane, bromodocosane. An example of a commercially available microcapsule PCM is Micronal™ from BASF. 
     Referring now to  FIG. 2 , an exemplary embodiment of a gypsum board  100  is shown. This embodiment illustrates another potential location option to allow the PCM to be proximate to a surface of the gypsum board. The gypsum board  100  comprises a board core  112  faced with a first facing material  114  and a second facing material  116 . A coating layer  118  is disposed on the first facing material  114 . An optional coating layer  122  can be disposed on facing material  116 . In this example, a plurality of capsules  120  containing PCM are located in a layer within the board core  112  itself. It is to be understood by a person of skill in the art that the choice of materials used in this embodiment can be the same as those mentioned above in relation to the embodiment shown in  FIG. 1 . 
     Referring now to  FIG. 4 , one convenient way to dispose the capsules in a layer within the board core is to meter them from a holding tank  401  into a separate stream of gypsum slurry at throughoutlet  417  to provide a relatively thin layer of aqueous calcined gypsum slurry  418  on the non-coated surface of sheet  416 . The thin layer of gypsum slurry  418  is somewhat more dense than the aqueous slurry of gypsum that is used to form the main portion of the core of the gypsum board (main core slurry discharged through outlet  419  from mixer  420  to form gypsum slurry layer  423 ). The slurry used to form the thin layer  18  is about 18-20% more dense than the density of the slurry  23  used to form the main portion of the core. A portion of this denser slurry also is often used to form hard edges of the gypsum board as well. The continuous sandwich of slurry and applied facing materials ( 414  and  416 ) is carried down conveyors  422 . 
     Other embodiments are envisioned where the PCM is applied downstream or upstream of the mixer such that the PCM is in proximity of the facing material. The challenge in these approaches is to provide a sufficient amount of gypsum slurry contact with the facing material. Vibrating tables may also be employed as a means of having the PCMs settle near the surface of the gypsum board. Additionally, the relatively more heavy macrocapsules compared to microcapsules can advantageously settle near the surface of gypsum board. 
     Referring now to  FIG. 3 , an exemplary embodiment of a gypsum board  200  is shown. This embodiment illustrates yet another potential location option to allow the PCM to be proximate to a surface of the gypsum board. The gypsum board  200  comprises a board core  212  faced with a first facing material  214  and a second facing material  216 . A coating layer  218  is disposed on the first facing material  214 . However, in comparison to the embodiment illustrated in  FIG. 1 , the plurality of capsules  220  containing PCM is present in a greater concentration near the surface of the facing material  214 . The challenge in this approach is to provide a sufficient amount of coating contact with the facing material to create a bond. 
     While  FIGS. 1-3  are discussed as separate embodiments for the purposes of illustration, it is to be understood that various combinations of these embodiments is envisioned. Embodiments are also envisioned where the facing material is eliminated. Further these boards can be laminated to other structures to provide multiple functions (e.g., sound abatement). 
     Advantageously, embodiments illustrated herein are helpful in creating a building material that when used in place of a similar building product without PCM provides greater energy efficiency in a build, which thereby can reduce carbon dioxide foot print of a building. 
     Ranges disclosed herein are inclusive and combinable (e.g., ranges of “up to about 25 wt %, or, more specifically, about 5 wt % to about 20 wt %”, is inclusive of the endpoints and all intermediate values of the ranges of “about 5 wt % to about 25 wt %,” etc.). “Combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by context, (e.g., includes the degree of error associated with measurement of the particular quantity). The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term. Reference throughout the specification to “one embodiment”, “another embodiment”, “an embodiment”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. 
     While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalent elements may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying this invention, but that the invention will include all embodiments falling within the scope of the appended claims.