RU2237640C2 - Gypsum-containing article showing enhanced resistance of constant deformation, method and composition for it preparing - Google Patents

Abstract

FIELD: building materials.

SUBSTANCE: invention proposes a gypsum-containing hardened article showing enhanced resistance of constant deformation and a method for it preparing. Method involves preparing a mixture of material based on calcium sulfate, water and sufficient amount of one or more improving agents taken among concentrated phosphoric acids each of that comprises 2 or some structural elements of phosphoric acids; and salts or ions of concentrated phosphates each of that comprises 2 or more structural elements of phosphates. Then mixture is kept under conditions providing the conversion of calcium sulfate-base material to material based on hardened gypsum. Invention provides preparing gypsum-containing articles showing enhanced strength, resistance of constant deformation and stability of sizes.

EFFECT: valuable properties of article.

48 cl, 19 tbl, 5 dwg, 14 ex

Description

The invention relates to a method for manufacturing and composition of gypsum-containing cured products, for example, gypsum panels, hardened gypsum composite panels, plaster, machined materials, materials for processing joints and soundproof tiles, and to methods for their preparation and their compositions. More specifically, the invention includes such hardened gypsum-containing articles that have increased resistance to constant deformation (for example, resistance to deflection) due to the use of one or more improving agents. In some preferred embodiments, the invention provides for the manufacture of such products by hydration of calcined gypsum in the presence of an improving agent that provides cured gypsum materials obtained by such hydration with increased strength, constant deformation resistance (e.g., deflection resistance) and dimensional stability (e.g., no shrinkage) during the drying of cured gypsum). The improving agent also provides an increase in other properties and advantages in the production of gypsum-containing cured products. In another embodiment of the invention, cured 2 gypsum is treated with one or more improving agents to obtain, if not the same, then similar, increased strength of continuous deformation (for example, resistance to deflection), dimensional stability and improvement of other properties and advantages of gypsum-containing products. In some embodiments of the invention, the gypsum-containing cured article of the present invention contains relatively high concentrations of hydrochloric acid salts, but eliminates the deleterious effect of such salt concentrations in the gypsum-containing articles.

Many well-known useful products contain hardened gypsum (calcium sulfate dihydrate) as an important, and often as a main component. For example, hardened gypsum is the main component of paper-coated gypsum panels used in typical structures of interior walls and dry masonry ceilings in buildings (see, for example, US Pat. Nos. 4,009,062 and 2,985,219). It is also a major component of composite panels and gypsum / cellulose fiber products, as described in US Pat. No. 5,320,677. The main part of the composition in products that fill and smooth the joints between the edges of gypsum panels is often gypsum (see, for example, US patent No. 3297601). Sound insulation tiles useful for use in suspended ceilings may contain a significant percentage of gypsum, as described, for example, in US Pat. usually depend mainly on the formation of set gypsum. The bulk of the composition of many special materials, such as materials useful for making models and molds that can be machined, as described in US Pat. No. 5,543,059, is gypsum.

Most of these gypsum-containing products are obtained by preparing a mixture of calcined gypsum (hemihydrate of calcium sulfate and / or calcium sulfate anhydride) and water (and other components, as necessary), pouring the mixture into the form of the desired configuration or on a plane and holding the mixture to solidify to form cured (i.e., re-hydrated) gypsum during the reaction of calcined gypsum with water to form a crystalline lattice of hydrated gypsum (calcium sulfate dihydrate). This is often accompanied by heating to moderate temperatures to remove residual free (unreacted) water to produce a dry product. Hydration of calcined gypsum is also desirable to ensure the formation of interconnected cells of the cured gypsum crystal lattice, thereby imparting strength to the gypsum structure in the gypsum-containing product.

All gypsum-containing products described above can be effective if the crystalline structure of the set gypsum in their components is increased in strength to obtain increased resistance to the stresses that may arise in them during use.

There is also a continuous tendency to produce many such gypsum-containing products lighter in weight by replacing part of their cured gypsum base with lower density materials (for example, with expanded perlite or with air pores). In these cases, there is a need to increase the strength of cured gypsum above normal levels, in order to only maintain the total strength of the product at the damage of the original product with a higher density, since less gypsum mass is present in the product with a lower density.

In addition, there is a need for higher permanent deformation resistance (for example, deflection resistance) in the structure of most of these gypsum-containing products, especially in conditions of high humidity and temperature, or even load. The human eye, as a rule, does not notice the sagging of the gypsum-containing panel with a deflection of less than about 2.54 mm along the panel length of 0.61 m. Thus, there is a need for gypsum-containing products that have sufficient resistance to permanent deformation over the life of such products. For example, gypsum-containing panels and tiles are often stored and used under conditions in which they are located horizontally. If the crystalline structure of hardened gypsum in these products does not have sufficient resistance to constant deformation, especially at high humidity and temperature, or even load, then the products may begin to bend in the areas between the points where they are attached to or rest on the underlying structure. This can spoil the appearance and cause difficulties when using the products. In many applications, gypsum-containing products must be able to bear loads, for example, single or concentrated loads without noticeable deflection. Thus, there is a continuing need for cured gypsum having increased resistance to constant deformation (e.g., deflection resistance).

There is also a need for higher dimensional stability of cured gypsum in gypsum-containing products during their manufacture and industrial use. Cured gypsum, especially in conditions of changing temperature and humidity, may shrink or expand. For example, moisture absorbed by the crystalline voids of a gypsum matrix in a gypsum panel or tile exposed to high humidity and temperature can increase the problem of deflection due to expansion of the moisture-saturated panel. In addition, in the manufacture of gypsum gypsum products, there is usually a significant amount of free (unreacted) water released from the matrix after gypsum is cured. This free water is essentially all removed by heating at moderate temperatures. As the evaporated water leaves the crystalline voids of the gypsum matrix, the matrix tends to shrink due to the natural forces of the cured gypsum (namely, the water is held by separate parts of the cured gypsum blocking crystals in the crystal lattice, which then tends to come closer together as water evaporation).

If such dimensional instability could be eliminated or minimized, various benefits could be gained. For example, using existing methods for producing gypsum panels, it would be possible to manufacture more products if the panels did not shrink during the drying process, and the necessary gypsum-containing products designed to maintain accurate shapes and dimensional proportions (for example, when used to make models and shapes) , could better serve for these purposes. In addition, for example, some types of plaster intended for the internal surfaces of walls of buildings may have advantages due to the absence of shrinkage during drying, so that the plaster could be better applied in thick layers without the risk of cracks than the need for many thin layers with long pauses to suitably dry between overlays.

Some specific types of gypsum-containing products also exhibit other specific problems. For example, gypsum-containing products with a lower density are often obtained by using blowing agents to form water bubbles in the dough (flowing water mixtures) from calcined gypsum, which form the corresponding permanent pores in the product when gypsum cures. This is often a problem because water foam is unstable, and therefore many bubbles can connect and exit relatively fluid dough (like bubbles in a hot tub) before gypsum cures, with significant concentrations of blowing agents to be used to obtain the desired concentration pores in gypsum to obtain a product with the desired density. This increases the costs and risks of the adverse effects of chemically active blowing agents on other components and properties of gypsum-containing products. It would be desirable to be able to reduce the amount of blowing agent needed to obtain the necessary pore concentration in gypsum-containing cured products.

There is also a need for new and improved compositions and methods for manufacturing gypsum-containing cured products made from mixtures containing high concentrations (namely, at least 0.015 wt.% With respect to the weight in a mixture of materials based on calcium sulfate) of chloride ions or their salts . Chloride ions or their salts can be contaminants in the calcium sulfate-based material itself or in water (for example, in sea water or in ground water containing brine) used in a mixture that could not be used to obtain gypsum-containing cured products before the present invention with stable properties.

There is also a need for new and improved compositions and methods for treating hardened gypsum to increase strength, resistance to permanent deformation (e.g., deflection resistance), and dimensional stability.

Thus, there is a continuing need for new and improved gypsum-containing products, compositions and methods for their preparation, which solve, eliminate or minimize the problems described above. The present invention satisfies these needs.

It was found that gypsum-containing cured products, compositions and methods for their preparation satisfy the needs described above. Each embodiment of the invention satisfies one or more of these needs.

A method of manufacturing a cured, gypsum-containing product having an increased resistance to constant deformation, comprising: obtaining a mixture of a material based on calcium sulfate, water, an accelerator and one or more improving agents selected from the group consisting of one or more of the following acids or salts, or anionic groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphate, tetracal potassium pyrophosphate, trisodium dipotassium tripolyphosphate, tetrasodium pyrophosphate, aluminum trimetaphosphate, acid pyroph sodium sulfate, ammonium polyphosphate having 1000-3000 repeating structural elements of phosphate, or polyphosphoric acid having 2 or more repeating structural elements of phosphoric acids, the mixture containing from about 0.015 to about 1.5 wt.% (relative to the weight of the material based on calcium sulfate in a mixture) of chloride ions or their salts, and maintaining the mixture under conditions sufficient to convert the material based on calcium sulfate to a material based on hardened gypsum with interconnected crystalline cells lattice, while the improving agent or agents are introduced into the mixture in such an amount that the gypsum-containing product has a higher resistance to permanent deformation than if the improving agent was not introduced into the mixture and the accelerator is introduced in such an amount that the gypsum-containing gypsum the product had a higher strength than if the accelerator were not introduced into the mixture.

In a method in which the concentration of the enhancing agent in the mixture can be from about 0.004 to 2.0% by weight relative to the weight of the calcium sulfate based material.

In the method, the concentration of the enhancing agent in the mixture may be from about 0.04 to 0.16% by weight relative to the weight of the calcium sulfate-based material.

In the method, the concentration of the enhancing agent in the mixture may be about 0.08% by weight relative to the weight of the calcium sulfate-based material.

In the method, the mixture may further include pre-gelatinized starch.

In the method, the calcium sulfate-based material may contain one or more of: calcium sulfate anhydride; calcium sulfate hemihydrate or calcium and sulfate ions.

In the method, the calcium sulfate-based material may include calcium sulfate hemihydrate.

In the method, the improving agent may include one or more of the following salts, or their anionic groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphates, and ammonium polyphosphate having 1000-3000 repeating structural elements of phosphates.

In the method, the mixture may contain 0.02-1.5 wt.% (Relative to the weight of the material based on calcium sulfate in the mixture) of chloride ions or their salts.

A gypsum-containing cured article may be manufactured as described above.

A gypsum panel having increased deflection resistance, comprising a core of laminate between coating sheets, in which the core contains hardened gypsum with interlocking cells with a crystal lattice, the panel being made by a method including:

the preparation or placement of the mixture between the coating sheets, the mixture comprising a material based on calcium sulfate, water, an accelerator and one or more improving agents selected from the group consisting of one or more of the following acids or salts, or their anionic groups: sodium trimetaphosphate, having 6-27 repeating structural elements of phosphate, tetracal-pyrophosphate, trisodium dipotassium tri-polyphosphate, tetrasodium pyrophosphate, aluminum trimetaphosphate, sodium hydrogen pyrophosphate, ammonium polyphosphate, having 1000-3000 repeating structural phosphate elements or polyphosphoric acid having 2 or more repeating structural elements of phosphoric acids, the mixture additionally containing from about 0.015 to about 1.5 wt.% (relative to the weight of the material based on calcium sulfate in the mixture) of chloride ions or their salts and maintaining the mixture under conditions sufficient to convert the calcium sulfate-based material into cured gypsum with interconnected cells of the crystal lattice, while the improving agent or agents are introduced into the mixture in such a quantity so that the gypsum panel has a higher deflection resistance than if the enhancing agent was not introduced into the mixture, and the accelerator was introduced in such an amount that the gypsum panel had a higher strength than if the accelerator was not introduced into the mixture.

In the gypsum panel, the concentration of the enhancing agent in the mixture may be from about 0.004 to 2.0 wt.% With respect to the weight of the calcium sulfate-based material or from about 0.04 to 0.16 wt.% With respect to the weight of the sulfate-based material calcium, or about 0.08 wt.% in relation to the weight of the material based on calcium sulfate.

In a gypsum panel, a calcium sulfate-based material may contain one or more of: calcium sulfate anhydride; calcium sulfate hemihydrate or calcium and sulfate ions.

In a gypsum panel, the enhancing agent may include one or more of the following salts, or their anionic groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphates, and ammonium polyphosphate having 1000-3000 repeating structural elements of phosphates.

In a gypsum panel, the mixture may contain 0.02-1.5 wt.% (Relative to the weight of the material based on calcium sulfate in the mixture) of chloride ions or their salts.

In the gypsum panel, the mixture may contain pregelatinized starch, the concentration of pregelatinized starch in the mixture being from about 0.08 to 0.5% by weight relative to the weight of the calcium sulfate-based material, or from about 0.16 to 0.4 wt.% in relation to the weight of the material based on calcium sulfate, or approximately 0.3 wt.% in relation to the weight of the material based on calcium sulfate.

In the gypsum panel, the core contains pores uniformly distributed in it, and the mixture further comprises water-based foam.

A gypsum panel in which water-based foam is obtained from a blowing agent or a mixture of blowing agents having the formula:

CH ₃ (CH ₂ ) _x CH ₂ (OCH ₂ CH ₂ ) _for OSO ₃ Θ M⊕

where X is a number from 2 to 20, Y is a number from 0 to 10 and is 0 at least 50 wt.% blowing agent or a mixture of blowing agents, and M is a cation.

In the gypsum panel, Y is 0 to 86-99% by weight of a blowing agent or a mixture of blowing agents.

In the gypsum panel, the mixture may further comprise pre-gelled starch and water-based foam.

A method of manufacturing a gypsum panel of a modified form, including:

preparing a homogeneous aqueous solution comprising water, at least one chloride salt, a wetting agent, and one or more improving agents selected from the group consisting of: phosphoric acids, each of which contains 1 or more structural elements of phosphoric acids; salts or ions of concentrated phosphates, each of which contains 2 or more structural elements of phosphates and monobasic salts or monovalent orthophosphate ions, and applying a homogeneous aqueous solution to the gypsum panel in an amount sufficient to soften the gypsum panel to facilitate changing the shape of the gypsum panel, changing the shape of the gypsum panels, as necessary, and drying the gypsum panel to obtain a gypsum panel of a modified form, with chloride salt, an improving agent or agents and wetting agents applied it is sufficient to provide a change in the form of the gypsum panel in a short time and a higher resistance to constant deformation of the changed gypsum panel than if the improving agent and wetting agent were not applied to the gypsum panel.

In the method, the applied solution may contain pre-gelled starch and, in addition, an anti-foam agent.

The applied solution may have a concentration of chloride salt of 0.05-1.0 wt.% With respect to the weight of the solution, a concentration of a wetting agent of 0.05-0.3 wt.% With respect to the weight of the solution, the concentration of improving agent 0.05-0 5 wt.% With respect to the weight of the solution, the concentration of starch is 0.025-0.2 wt.% With respect to the weight of the solution, the concentration of antifoam agent is 0.01-0.05 wt.% With respect to the weight of the solution.

The gypsum panel may be a paper coated panel.

A homogeneous water-based solution can only be applied to one side of the gypsum board.

The gypsum panel of a modified form can be manufactured in the above manner.

A method of manufacturing a gypsum panel of a modified form, including:

applying to a gypsum panel a homogeneous water-based solution containing water and a wetting agent, applying to a gypsum panel a homogeneous water-based solution containing water and at least one chloride salt, applying to a gypsum panel, before drying, a solution containing one or more improving agents selected from the group consisting of: phosphoric acids, each of which contains 1 or more structural elements of phosphoric acids; salts or ions of concentrated phosphates, each of which contains 2 or more structural elements of phosphates and monobasic salts or monovalent ions of orthophosphates, changing the shape of the gypsum panel, as necessary, and drying the gypsum panel to obtain a gypsum panel of a changed shape, the chloride salt improving agent or the agents and wetting agents are applied to the gypsum board in an amount sufficient to provide a change in the shape of the gypsum board in a short time and higher resistance to constant deformation and a gypsum panel of a changed shape than if no improving agent and wetting agent were applied to the gypsum panel.

In the method, a solution containing pregelatinized starch, as well as a solution containing an antifoam agent, can also be applied to the gypsum panel before drying.

Moreover, the applied solution containing chloride salt may have a concentration of chloride salt of 0.05-1.0 wt.% In relation to the weight of the solution.

In the method, the applied solution containing a wetting agent may have a concentration of a wetting agent of 0.05-0.3 wt.% With respect to the weight of the solution, the applied solution containing a improving agent may have a concentration of a improving agent of 0.05-0.5 weight % with respect to the weight of the solution, the applied solution containing starch may have a starch concentration of 0.025-0.2% by weight with respect to the weight of the solution.

In the method, the applied solution containing the antifoam agent may have a concentration of antifoam agent of 0.01-0.05 wt.% With respect to the weight of the solution.

The gypsum panel may be a paper coated panel.

In the method, the chloride salt, the improving agent or agents and the wetting agent can be applied only on one side of the gypsum board.

The gypsum panel of a modified form can be made in the above way.

All of the improved materials described above will have increased resistance to permanent deformation in the resulting set gypsum. However, some improving agents (for example, the following salts or their anionic groups: sodium trimetaphosphate (which is also referred to here as TMPN) having 6-27 repeating phosphate structural units (which is also referred to here as GMPH), and ammonium polyphosphate having 1000-3000 the repeating structural units of phosphate (which is also referred to here as PFA)) will provide benefits such as a very significant increase in deflection resistance. In addition, PFA receive the same deflection resistance that is obtained from TMPN, even when only one fourth of the concentration of TMPN is added.

In some preferred embodiments of the present invention, this is accompanied by the addition of a trimetaphosphate ion to a mixture of calcined gypsum and water to be used in the preparation of gypsum-containing cured products (the term “calcined gypsum”, as used here, means hemi calcium sulfate hemihydrate, calcium beta sulfate hemihydrate, water soluble calcium sulfate anhydride or a mixture of any or all of them, and the terms “gypsum gypsum” and “hydrated gypsum” mean calcium sulfate dihydrate). It was found that when water in a mixture spontaneously reacts with calcined gypsum to form hardened gypsum, it increases strength, resistance to constant deformation (for example, resistance to deflection) and dimensional stability compared to hardened gypsum obtained from a mixture that does not contain trimetaphosphate ion. The mechanism of this increase in properties is incomprehensible.

In addition, it was found that a trimetaphosphate ion (like PFA) does not slow down the rate of conversion of hardened gypsum from calcined gypsum. Indeed, when the trimethaphosphate ion is added at relatively high concentration levels within its effective addition ranges, it even accelerates the hydration rate of calcined gypsum to form hardened gypsum. This is especially unexpected since there is an increase in the strength of cured gypsum because gypsum experts generally believe that phosphoric acid derivatives or phosphates slow down the rate of formation of cured gypsum and reduce the strength of the gypsum obtained. In fact, this is true for most of these materials, but not for the trimetaphosphate ion. In general, in some preferred embodiments, the present invention provides a method for producing a gypsum-containing cured article having increased strength, constant deformation resistance (e.g., deflection resistance), and dimensional stability, including: forming a mixture of calcined gypsum, water and a trimethaphosphate ion and holding the mixture under conditions (for example, at a temperature, preferably below about 48.9 ° C.), sufficient to convert calcined gypsum into set gypsum.

In certain preferred embodiments, the present invention provides a method for producing a gypsum board comprising a core of cured gypsum layers between sheets of paper or other materials. The panel is made by obtaining a fluid mixture (suspension) of calcined gypsum, water and a trimetaphosphate ion, introducing it between the coating sheets and holding the resulting preform for curing and drying.

Although the panel thus obtained has all the necessary improved properties: increased strength, resistance to constant deformation (for example, deflection resistance), and dimensional stability, it was found that for unknown reasons, when such a panel was wetted for some reason or was not completely dried in the process of manufacture, the bond between the gypsum core and the coating sheets (usually including paper) can lose strength or even break down even when the panel contains a typical, non-gelled pre preliminarily starch (e.g., acid-modified starch) which normally contributes to improving the integrity of communications with a core of paper. The coating sheets may then peel off from the panel, which may be unsuitable. A solution was found to this potential problem. It has been found that the problem can be eliminated by introducing pregelatinized starch into the resulting suspension. This starch was then dispersed throughout the resulting gypsum core, and it was found that this eliminates the weakening of the bond between the core and the coating sheets.

Thus, in some of the embodiments of the present invention, a composition and method for producing more improved gypsum panels are provided. The composition includes a mixture of water, calcined gypsum, a trimetaphosphate ion and pregelatinized starch. The method includes obtaining such a mixture, introducing it between the sheets of the coating and ensuring curing and drying of the resulting preform.

In the case where it is necessary to obtain a lighter gypsum panel, the present invention provides a composition and method for doing this. The composition includes a mixture of water, calcined gypsum, a trimetaphosphate ion and a water-based foam, and the method includes preparing such a mixture, introducing it between the coating sheets and holding the resulting preform for curing and drying. This composition and method provides a lighter panel due to the fact that the bubbles of water-based foam lead to the formation of air pores in the core of the cured gypsum of the finished panel. The total strength of the panel is higher than the panels obtained by known technologies with the introduction of water-based foam into the mixture, since increased strength is obtained by introducing the trimethaphosphate ion into the mixture used to obtain the panel in accordance with the present invention. For example, 12.7 mm thick ceiling panels made in accordance with the present invention have significantly higher permanent deformation resistance (for example, deflection resistance) than 15.88 mm thick ceiling panels made by compositions and methods of known manufacturing processes. Thus, the present invention provides cost savings in the manufacture of ceiling panels.

Another advantage has been discovered from incorporating a trimetaphosphate ion into a mixture also containing water-based foam. Namely, it was found that in the finished gypsum-containing product, proportionally more air pores (and a larger total pore volume) are formed per unit amount of water-based foam used when the trimethaphosphate ion is introduced into the mixture. The reason for this is unknown, however, the advantage is that less blowing agent can be used to obtain the desired amount of air pores in the gypsum-containing cured article. This, in turn, results in lower production costs and a lower risk of adverse effects of chemically active blowing agents on other components or properties of the gypsum-containing product.

In some embodiments of the present invention, there is provided a composite panel comprising gypsum and a reinforcing material made by molding or placing the mixture on a surface, the mixture comprising a reinforcing material, calcium sulfate-based material, water and an acceptable amount of one or more enhancing agents selected from concentrated phosphoric acids, each of which contains 2 or more structural units of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates. The mixture is then maintained under conditions sufficient to convert the calcium sulfate-based material to the set gypsum-based material.

The present invention also provides a composite panel comprising cured gypsum and foreign particles, wherein at least a portion of the cured gypsum is within and near accessible pores in the foreign particles. The panel is made by molding or placing the mixture on the surface, the mixture comprising: foreign particles; calcium sulfate hemihydrate, at least a portion of which in the form of crystals is located inside or near the pores of foreign particles; water and an acceptable amount of one or more enhancing agents selected from the group consisting of concentrated phosphoric acids, each of which contains 2 or more structural units of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates. The mixture is then held under conditions sufficient to convert calcium sulfate hemihydrate to gypsum, whereby part of the gypsum inside or near accessible pores in the foreign particles causes hydration of the calcium sulfate hemihydrate crystals in or near the pores of the foreign particles.

The present invention also provides a gypsum-containing cured mechanically processed product made by molding a mixture containing starch, particles of a water-redispersible polymer, a calcium sulfate-based material, water, and a sufficient amount of one or more improving agents selected from:

concentrated phosphoric acids, each of which contains 2 or more structural units of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates. The mixture is then maintained under conditions sufficient to convert the calcium sulfate-based material to the set gypsum-based material. The present invention also provides a gypsum-containing cured product used to seal joints between the edges of gypsum panels, the product being prepared by mixing a joint comprising a binding agent, a thickener, a non-smoothing agent, calcium sulfate-based material, water and a sufficient amount of one or more improvers agents selected from concentrated phosphoric acids, each of which contains 2 or more structural units of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates. The mixture is then maintained under conditions sufficient to convert the calcium sulfate-based material to the set gypsum-based material.

The present invention also provides a gypsum-containing cured soundproofing tile made by molding or placing in a pan a mixture containing starch, water particles, expanded perlite, calcium sulfate-based material, water, and a sufficient amount of one or more improving agents selected from: concentrated phosphoric acids , each of which contains 2 or more structural units of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates. The mixture is then maintained under conditions sufficient to convert the calcium sulfate-based material to the set gypsum-based material.

The present invention also provides gypsum-containing cured articles made by molding a mixture of an improving agent, calcium sulfate dihydrate and water. More specifically, these embodiments of the invention include treating the gypsum casting with an improving agent. Upon receipt of a mixture of an improving agent, water and calcium sulfate dihydrate, it was found that gypsum-containing products having increased strength, constant deformation resistance (e.g., deflection resistance) and dimensional stability could be obtained. Such subsequent curing treatment may be accompanied by the administration of an improving agent or by spraying or impregnating the casting from calcium sulfate dihydrate with an improving agent. In the case of such subsequent curing treatment, the improving agent is selected from the group consisting of: concentrated phosphoric acids, each of which contains 1 or more structural units of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates and monobasic salts or monovalent ions of orthophosphates.

In some embodiments, the present invention provides a composition and method for producing gypsum-containing cured products from mixtures containing high concentrations of chloride ions or their salts (for example, at least 0.015 wt.%, By weight in a mixture of materials based on calcium sulfate). Chloride ions or their salts can be impurities in the material based on calcium sulfate or in water (for example, in sea water or in subsoil water containing brine) used in a mixture that until the present invention could not be used to obtain stable, gypsum-containing cured products.

In addition, it was found that the preliminary curing treatment of the calcium sulfate-based material in accordance with the present invention slows down the hydration rate during the formation of the set gypsum and adversely affects the strength of the set gypsum-containing product. It was found that this retardation and adverse effect on strength can be neutralized or even prevented by introducing the accelerator into the mixture in a sufficient amount and in an appropriate manner.

In addition, it was found that a gypsum panel having the desired shape can be made in accordance with the principles of the present invention. Prior to the present invention, the shape of a normal flat gypsum panel was usually changed by moistening the panel with water until the panel softened and became more flexible, and then the panel was given the desired shape, and after that they waited for the panel to dry. However, this prior technology leads to many problems in the production and on the equipment, since the humidification necessary to soften the panel and give it more flexibility so that it can be given the desired shape takes a lot of time, namely at least one hour or more, and often requires twelve hours. In addition, prior technology is not well suited for easily changing the panel to the desired shape. If the panel is not softened enough, then difficulties arise when giving it the desired shape. Namely, more force is required to give the desired shape to the panel, and if too much force is applied, the panel may be broken. Thus, there is a great need to develop methods and compositions that would reduce the wetting time and facilitate the process of shaping the gypsum panel.

According to a preferred embodiment of the present invention, for example, an aqueous chloride solution containing any enhancing agent (as described above in this brief description of the present invention and in the examples below) can be sprayed onto a flat gypsum panel to soften the panel and give it more flexibility. Then, a softened and more flexible panel can be easily shaped to fit with less effort than with prior technologies, and the desired shape of the modified panel will be retained after the panel dries due to the beneficial effect of the enhancing agent.

1 is a graph showing the weight of finished gypsum panels, including a gypsum panel in accordance with the present invention.

Figure 2 presents a graph comparing the deflection resistance of a gypsum panel made in accordance with the present invention, with industrially produced gypsum panels, of which all tested panels were attached to the ceiling using conventional staplers and screw connections. FIG. 3 is a graph comparing the deflection resistance of a gypsum panel made in accordance with the present invention with commercial gypsum panels, of which all tested panels were attached to the ceiling using conventional F2100 fixing means (i.e., glue).

Figure 4 presents a graph comparing the changes in the deflection of the gypsum panels made in accordance with the present invention, and industrially produced gypsum panels.

Fig. 5 is a graph showing the effect on the boom of processing a gypsum panel in accordance with the present invention obtained from a gypsum panel containing pre-cured and dried gypsum (namely, calcium sulfate dihydrate).

The present invention can be put into practice by using compositions and methods similar to those used in the previous technical solutions for the manufacture of various products containing hardened gypsum. A significant difference in the compositions and methods of some preferred variants of the present invention from the compositions and methods used in the preceding technical solutions for the preparation of various gypsum-containing cured products is that in the methods of the present invention, a salt of trimethaphosphate is introduced to re-hydrate the calcined gypsum so that in the presence of the trimetaphosphate ion, it was converted into gypsum, thereby realizing the advantage of the present invention. In other respects, the compositions and methods of the invention may be the same as the corresponding compositions and methods of the prior art.

The trimetaphosphate salt incorporated into the compositions of the present invention can be any water soluble trimetaphosphate salt that does not adversely affect when interacting with other components of the mixture. Some examples of suitable salts include sodium trimetaphosphate, potassium trimetaphosphate, ammonium trimetaphosphate, lithium trimetaphosphate, aluminum trimetaphosphate, and mixtures of these salts, among others. They are commercially available and are readily available, for example, from Soluta Inc., St. Louis, Missouri, previously a division of Monsanto Company, St. Louis, Missouri.

When practicing one of the preferred embodiments of the present invention, the trimetaphosphate salt is dissolved in a water-based mixture of calcined gypsum to obtain a concentration of trimetaphosphate ion from about 0.004 to 2.0 wt.% With respect to the weight of calcined gypsum. A preferred concentration of the trimetaphosphate ion is from about 0.04 to 0.16% by weight. A more preferred concentration is about 0.08% by weight. If in the practical use of some variants of the present invention it is required to facilitate storage and delivery, the salt of the trimetaphosphate can be pre-dissolved in water and introduced into the mixture in the form of an aqueous solution.

According to a preferred embodiment of the present invention, the trimetaphosphate ion should be present in the water-based mixture of calcined gypsum only during hydration of the calcined gypsum to form hardened gypsum. Therefore, although it is usually most convenient and thereby preferable to introduce the trimethaphosphate ion into the mixture at an early stage, it is also sufficient to introduce the trimethaphosphate ion into the mixture of calcined gypsum and water at a rather late stage. For example, in the manufacture of typical gypsum panels, water and calcined gypsum are introduced together into a mixer, mixed thoroughly, and then usually spread over a coating sheet on a moving belt, and a second coating sheet is placed on top of the distributed mixture before the main part of the rehydration of the calcined gypsum with the formation of hardened gypsum. Although it is most convenient to introduce the trimetaphosphate ion into the mixture during its preparation in the mixer, it is also acceptable to introduce the trimetaphosphate ion at the very last stage, namely, by spraying an aqueous solution of the ion onto a distributed mixture of calcined gypsum with water immediately before placing the second coating sheet on top of the mixture, with so that the aqueous solution of the trimetaphosphate ion is absorbed into the decomposed mixture and is present in it when the bulk of hydration occurs with the formation of hardened gypsum.

Other alternative methods of introducing a trimethaphosphate ion into the mixture are familiar to those skilled in the art, given that they should be within the scope of the present invention. For example, a trimetaphosphate salt may be preliminarily applied to one or both of the coating sheets so that the salt dissolves and the trimethaphosphate ion penetrates into the mixture when the layer of the aqueous mixture of calcined gypsum comes into contact with the coating sheet. Another alternative is to mix the trimetaphosphate salt with raw gypsum just before it is heated to produce calcined gypsum, so that the salt is already in the gypsum when the calcined gypsum is mixed with water to cause rehydration.

Other alternative methods of introducing the trimethaphosphate ion into the mixture are to add the trimethaphosphate ion to the cured gypsum using any suitable means, such as spraying or soaking the cured gypsum with a solution containing trimethaphosphate. It has been found that the trimethaphosphate ion will migrate into the cured gypsum through ordinary sheets of paper used in the treatment of cured gypsum.

Calcined gypsum used in accordance with the present invention may be in the form and concentration, which are usually suitable in the corresponding variants of the previous technical solutions. It can be hemihydrate calcium alpha sulfate, hemihydrate beta calcium sulfate, water soluble calcium sulfate anhydride, or mixtures of any or all of them, from natural or synthetic sources. In some preferred embodiments, calcium alpha sulfate hemihydrate is used to produce set gypsum having relatively high strength. In other preferred embodiments, calcium beta sulfate hemihydrate or a mixture of calcium beta sulfate hemihydrate with water soluble calcium sulfate anhydride are used.

In the practical use of the present invention, other conventional additives in conventional amounts can be used to impart desired properties and facilitate production, such as, for example, water-based foam, accelerators, curing inhibitors, re-calcination inhibitors, binders, adhesives, dispersion accelerators, smoothing or non-smoothing agents, thickeners, bactericides, fungicides, pH regulators, dyes, hardening materials, fire fighting agents, water repellent e agents, fillers and mixtures thereof.

In some preferred embodiments of the present invention, in which the method and composition is used to make gypsum panels comprising a core of gypsum-containing material between the coating sheets, the trimethaphosphate ion is used in the concentration and method described above. In other aspects, the same components can be used in practice and method in the same manner as in the compositions and methods for manufacturing gypsum panels in accordance with the prior art, for example, as described in US Pat. Nos. 4,009,062 and 2,985,219, the descriptions of which are incorporated in this application by reference. The panels obtained using this preferred composition and method in accordance with the present invention exhibit increased strength, continuous deformation resistance and dimensional stability.

Preferred methods and compositions for producing gypsum panels, in which the surface sheets of the panel include paper, also use pregelatinized starch to avoid otherwise increasing the risk of paper peeling under conditions of high humidity. Pregelatinization of raw starch is performed by brewing it in water at a temperature of at least 85 ° C or using other well-known methods.

Some examples of available easily gelatinized starches that accomplish the objectives of the present invention are (their trade names are given): PCF1000 starch, supplied by Lauhoff Grain Co .; and AMERIKOR 818 and HQM PREGEL starches, both supplied by Archer Daniels Midland Co.

When used in practice in preferred embodiments of the present invention, the pregelatinized starch is added to the aqueous mixture of calcined gypsum at a concentration of from about 0.08 to 0.5% by weight based on the weight of the calcined gypsum. A preferred concentration of pregelatinized starch is from about 0.16 to 0.4% by weight. A more preferred concentration is about 0.3%. If starch which is not pregelatinized (as is done in many cases) is also used in an appropriate embodiment of the preceding technical solution, then the pregelatinized starch in accordance with the present invention can also serve to replace all or part of the amount of starch that is usually used in the preceding technical decision.

In embodiments of the present invention that use a blowing agent to produce pores in a gypsum-containing gypsum-containing article for weight relief, any of the usual foaming agents known as suitable for making foamed gypsum-based products can be used. Many such blowing agents are well known and readily available in markets, for example, from GEO Specialty Chemicals, Amb-ler, PA. For further information on suitable blowing agents, see, for example, US Pat. Nos. 4,676,835; 5,186,612; 5,240,639 and 5,643,510 and the publication of PCT International Patent Application WO 95/16515, published June 22, 1995.

In many cases, it should be preferable to obtain relatively large pores in the gypsum product in order to maintain its strength. This can be accomplished by using a foaming agent that forms a foam, which is relatively unstable when in contact with a suspension of calcined gypsum. Preferably this is accomplished by mixing the bulk of the blowing agent known as forming a relatively unstable foam with a smaller amount of blowing agent known as forming a relatively stable foam.

Such blowing agent mixtures can be pre-prepared “off-site”, i.e. separate from the process for producing a foamed gypsum product. However, it is preferable to mix such blowing agents in a consistent and continuous manner, such as one of the process steps carried out “in a stream”. This can be done, for example, by pumping separate streams of various blowing agents into the pump and co-feeding the streams into or just in front of the foam generator, which is used to create a water-based foam stream, which is then introduced into the suspension of calcined gypsum and mixed with it. With this mixing, the ratio of blowing agents in the mixture can be simply and effectively controlled (for example, by changing the flow rate of one or both separate streams) to obtain the desired pore concentrations in the foamed article from the set gypsum. Such regulation should be done after checking the finished product to determine if such regulation is necessary. A further description of such in-stream mixing and control can be found in US Pat. No. 5,643,510 and in simultaneously filed US Patent Application 08/5773676, filed December 22, 1995. An example of one type of blowing agent suitable for producing an unstable foam has the formula

where R is an alkyl group containing from 2 to 20 carbon atoms, and M represents a cation. Preferably R is an alkyl group containing from 8 to 12 carbon atoms.

An example of one type of blowing agent suitable for producing a stable foam has the formula

where X is a number from 2 to 20, Y is a number from 0 to 10 and is greater than 0 at least 50 wt.% blowing agent, and M is a cation.

In some preferred embodiments of the present invention, blowing agents having the above formulas (Q) and (J) are mixed together so that a blowing agent of the formula (Q) and a portion of the blowing agent of the formula (J) in which Y is 0 are together from 86 to 99% by weight of the final blowing agent mixture.

In some preferred embodiments of the present invention, the water-based foam is obtained from a pre-mixed blowing agent having the formula:

where X is a number from 2 to 20, Y is a number from 0 to 10 and is 0 at least 50 wt.% blowing agent, and M is a cation. Preferably, Y is 0 to 86-99% by weight of a blowing agent of formula (Z).

In some preferred embodiments of the present invention, in which the method and composition is used to obtain a composite panel containing gypsum and hardening particles of the material, the trimethaphosphate ion is used in concentrations and in the same manner as described above. It is particularly preferred that the composite product contains cured gypsum and foreign particles, with at least a portion of the cured gypsum located inside or near accessible pores in the foreign particles. The composition in accordance with the present invention includes a mixture of: foreign particles having accessible pores; calcined gypsum, at least a portion of which is in the form of crystals inside or near pores in foreign particles; and water soluble salts of trimetaphosphate. The components of the composition can be mixed with water to obtain in accordance with the present invention a mixture of water, foreign particles having accessible pores, calcined gypsum (at least part of which is in the form of crystals inside or near the pores in foreign particles) and a trimethaphosphate ion. The method includes obtaining such a mixture, placing it on a plane or in a mold and keeping it for curing and drying. In other cases, the composition and method can be used in practice with the same components and in the same way as when using the compositions and methods to obtain a composite panel in accordance with the previous technical solutions, for example, as described in US patent No. 5320677, the description of which included in this application by reference.

In some preferred embodiments of the present invention, in which the method and composition is used to make a machined material, the trimethaphosphate ion is used in concentrations and in the same manner as described above. In some preferred forms of such embodiments, the composition includes a mixture of calcined gypsum, a water-soluble trimetaphosphate salt, starch, and particles of a water-redispersible polymer. The components of the composition can be mixed with water to obtain a mixture of water, calcined gypsum, a trimetaphosphate ion, starch and particles of a water redispersible polymer. The method includes obtaining such a mixture, placing it on a plane or in a mold and keeping it for curing and drying. As for other aspects than the introduction of salts and ions of trimethaphosphate, the composition and method can be applied in practice by using the same components and in the same way as when using the appropriate compositions and methods to obtain a mechanically processed plaster material in accordance with the previous technical solutions, for example, as described in US Pat. No. 5,543,059, the disclosure of which is incorporated herein by reference. In some preferred embodiments of the present invention, in which the method and composition is used to obtain the material used to seal the joints between the edges of the gypsum panels, the salts and ions of trimethaphosphate are used in the concentrations given above. As for other aspects than the introduction of salts and ions of trimetaphosphate, the composition and method can be applied in practice by using the same components and in the same way as when using the appropriate compositions and methods to obtain material for sealing joints in accordance with the previous technical solutions, for example, as described in US patent No. 3297601, the description of which is incorporated into this application by reference. In some preferred forms of such options, the composition includes a mixture of calcined gypsum, a water-soluble salt of trimetaphosphate, a binding agent, a thickening agent and a non-smoothing agent. The components of the composition can be mixed with water to obtain, in accordance with the present invention, a mixture of calcined gypsum, a trimetaphosphate ion, a binder, a thickening agent and a non-smoothing agent. The method includes obtaining such a mixture, introducing it into the joint between the edges of the gypsum panels and keeping it for curing and drying.

In such preferred embodiments for sealing joints, a bonding agent, a thickening agent, and a non-smoothing agent are selected from components well known to those skilled in the art for sealing joints. For example, the bonding agent may be a conventional latex bonding agent, with poly (vinyl acetate) and poly (ethylene-co-vinyl acetate) being preferred and to be formulated in the range of about 1 to 15% by weight of the mixture. An example of a suitable thickener is a cellulosic thickener, for example ethyl hydroxyethyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxypropyl cellulose or hydroxyethyl cellulose, which are introduced in the range of about 0.1 to 2% by weight of the mixture. Examples of suitable non-smoothing agents are clays of attapulgite, sepiolite, bentolite and montmorillonite, which are introduced in the range of about 1 to 10% by weight of the mixture.

In some preferred embodiments of the present invention, in which the method and composition is used to make a sound insulating tile, the trimethaphosphate ion is introduced at the concentrations given above. In some preferred forms of these options, the composition includes a mixture of water, calcined gypsum, a trimetaphosphate ion, gelatinized starch and mineral wool, or a mixture of water, calcined gypsum, a trimetaphosphate ion, gelatinized starch, expanded perlite particles and reinforcing fibers. The method includes obtaining such a mixture, pouring it into a pallet and keeping it for curing and drying. With regard to another aspect than the introduction of a trimetaphosphate ion, the composition and method can be used in practice with the same components and in the same way as the use of appropriate compositions and methods for producing soundproofing tiles in accordance with the previous technical solutions, for example, as described in patents US No. 5395438 and 3246063, the description of which is incorporated into this application by reference.

The following examples are presented to further illustrate some preferred embodiments of the present invention and to compare them with methods and compositions that are outside the scope of the claims of the present invention. Unless otherwise specified, the concentrations and materials in the compositions and mixtures are given in weight percent relative to the weight of the calcined gypsum present. The abbreviation "TMF" is accepted for sodium trimetaphosphate, and "TMF" for trimetaphosphate.

EXAMPLE 1

Laboratory tests for compressive strength of a cube

Samples of gypsum-containing products were made in accordance with the present invention and compared for compressive strength with samples made using various methods and compositions. The test procedure was used in accordance with ASTM standard C472-93.

Samples were prepared by dry mixing: 500 g of calcium beta-sulfate hemihydrate, 0.6 g of curing accelerator, containing finely ground particles of calcium sulfate dihydrate, coated with sugar to maintain chemical activity and heated, as described in US patent No. 3573947, the description of which is included to this application by reference; and 0 g of additives (control samples), 0.5-2 g of TMPN (preferred samples of the present invention) or 0.5-2 g of additives of other phosphates (comparison samples). Then, samples of the compositions were mixed with 700 ml of tap water having a temperature of 21.11 ° C. in a 2 liter WARING mixer, allowed to soak for 5 seconds and mixed at low speed for 10 seconds. The suspensions thus obtained were poured into molds for making cubes (with a side of 50.8 mm). After the curing of the calcium sulfate hemihydrate with the formation of gypsum (calcium sulfate dihydrate), the cubes were removed from the molds and dried in a ventilated oven at a temperature of 44.44 ° C for at least 72 hours or until the weight change stopped . The dried cubes had a density of approximately 0.705 g / m ³ .

The compressive strength of each dried cube was measured on a ZATES test machine. The results are shown in table 1 as averaged values for the three tested samples. The strength values of the control samples varied because calcium beta-sulfate hemihydrate from various sources and / or various portions of calcium beta-sulfate hemihydrate were used. The results in the table are presented in the form of measured compressive strength in pounds per square inch (psi) and changes in strength in percent over the corresponding control sample (Δ%). It was determined that the measured values had an experimental error of approximately +/- 5% (thus, the presented increase in strength above the control sample by 10% could actually be in the range of about 5-15%).

The data in table 1 show that the samples (PMS) in accordance with the present invention, as a rule, show significantly higher strength compared to the control, while the comparison samples show, as a rule, a very slight increase or no increase, or even a significant decrease in strength .

EXAMPLE 2

Continuous deformation resistance (laboratory tests of gypsum panel deflection resistance)

Samples of gypsum-containing panels were made in the laboratory in accordance with the present invention and compared for the resistance to continuous deformation of the samples of panels obtained using methods and compositions that are outside the scope of the claims of the present invention.

Samples were prepared by mixing in a 5-liter WARING mixer for 10 seconds at low speed: 1.5 kg of calcium beta-sulfate hemihydrate; 2 g of accelerator, as previously defined; 2 l of tap water and 0 g of the additive (control samples), 3 g of TMF (samples in accordance with the present invention), or 3 g of other additives (comparison samples). The suspensions thus obtained were poured into trays to obtain samples of flat gypsum panels, each measuring approximately 15.24 x 60.96 x 1.27 cm. After the curing of calcium sulfate hemihydrate to form gypsum (calcium sulfate dihydrate), the panels were dried in an oven at a temperature of 44.44 ° C until the change in weight has stopped. The final measured weight of each panel was recorded. No paper coatings were applied to these panels to exclude the effect of paper coatings on the deflection characteristics of gypsum panels under wet conditions.

Then the dried panel was laid horizontally on two supports 12.7 mm wide, the length of which corresponded to the full width of the panel, with one support at each end of the panel. The panels were left in this position for a certain period of time (for 4 days in this example) under constant environmental conditions: temperature 32.22 ° C and relative humidity 90%. The degree of deflection of the panel was then determined by measuring the distance (in inches) of the center of the upper surface of the panel from an imaginary horizontal plane passing between the upper edges of the ends of the panels. It was found that the resistance to constant deformation of the matrix from the cured gypsum panel is inversely proportional to the deflection of the panel. Thus, the greater the degree of deflection, the lower the relative resistance to permanent deformation containing the cured gypsum matrix of the panel.

The test results of the resistance to constant deformation are shown in table 2, which includes the composition and concentration of the additive (in weight percent relative to the weight of calcium sulfate hemihydrate), the final weight of the panel and the measured degree of deflection. The additives used in the comparison samples (outside the scope of the claims of the present invention) were other materials that were used in an attempt to increase the resistance of the gypsum panel to deflection in high humidity conditions.

The data in table 2 show that the panel (TMPN) made in accordance with the present invention had a significantly higher deflection resistance (and thus a significantly higher constant deformation resistance) than the control panel and comparison panels not related to the present invention. In addition, the panel made in accordance with the present invention had a deflection that was significantly less than a deflection of 2.54 mm per 0.6096 m of the panel length (4.17 mm per 1 meter of length), and thereby deflection invisible to the human eye.

EXAMPLE 3

Resistance to constant deformation (resistance to deflection of gypsum panels obtained on the production line)

A comparison of the weight of the products is shown in figure 1, and the deflection resistance of such products is shown in figures 2 and 3. The weight of the finished ceiling panels with a thickness of 12.7 mm for interior decoration in accordance with the present invention (i.e., when mixing trimetaphosphate with calcined gypsum and water) was the same as the weight of typical SHEETROCK® gypsum panels 12.7 mm thick for interior fittings manufactured by the United States Gyp-sum Company. The middle 12.7 mm thick ceiling panel shown in FIG. 1 is a Gold Bond® high strength ceiling panel manufactured by Nati-onal Gypsum Company. The average gypsum panel with a thickness of 15.88 mm shown in FIG. 1 is a SHEETROCR® Firecode gypsum panel, type X, manufactured by the United States Gypsum Company.

Figure 2 presents a graph comparing the deflection resistance of a gypsum panel made in accordance with the present invention, with the gypsum panels manufactured by the industry described above, of which all tested panels were installed using conventional fastening means with a stapler and screws.

Figure 3 shows a graph comparing the deflection resistance of a gypsum panel made in accordance with the present invention with commercial gypsum panels, of which all tested panels were fixed to the ceiling using conventional two-component urethane adhesive F2100.

The gypsum panels and other structural parts used for the deflection comparisons shown in FIGS. 2 and 3 were as follows:

A. Gypsum panel:

1. 1.27 × 121.92 × 243.84 cm manufactured in accordance with the present invention;

2. High strength ceiling panel 1.27 × 121.92 × 243.84 cm, pold Bond® from National Gypsum Company;

3. A typical SHEETROCK® gypsum panel with dimensions of 1.27 × 121.92 × 243.84 cm;

manufactured by United States Gypsum Company;

4. Gypsum board 1.59 × 121.92 × 243.84 cm SHEETROCK®, Firecode, Type X, manufactured by United States Gypsum Company.

B. Beams: height 45.82 cm × length 259.08 cm made of lumber with a nominal size of 50.8 × 76.2 mm by R.J. Cole, Inc. USG Tuff Set HES Joint Compound. Joint Tape - USG fiberglass mesh adhesive tape.

C. Steam-tight paint - No. 4512 Silver Vapor Barrier, item No. 246900.

D. Insulation - Injected cotton Delta Blowing Insulation, Rockwool mineral fiber.

E. Spray Textured Medium - Multilayer Medium

Ceiling Spray Texture QT, SHEETROCK®, USG.

F. Fasteners - brackets of [16th] caliber measuring 25.4x31.75 mm and screws for dry plaster No. 6 with a length of 31.75 mm. F2100 two-component urethane adhesive from Fofmseal, Inc.

Ceiling construction:

A. 2 × 4 beams were connected at both ends of the beams to produce a framework of beams.

B. Twelve (12) gypsum panels are fastened to the beam frame with F2100 glue. An edge with an average width of 25.4 mm was measured on gypsum panels.

C. The ceiling was carefully raised and placed on top of the pre-mounted four walls to obtain a room of 2.44 x 14.63 m.

D. The assembled ceiling was attached around the entire perimeter to the top wall plate with 88-mm screws 8 in length. The second ceiling was constructed using screws and staples for attaching gypsum panels to the beams. The ceiling was also raised and attached to four (4) walls.

Two (2) ceilings were constructed using three (3) pieces of gypsum panels of each type on each ceiling. One ceiling was attached mechanically, while the other was attached only with F2100 urethane adhesive (see figure 3). Gypsum panels were laid with alternating types of panels along the ceilings. The beams used were 2.567 m long, 45.82 cm high and spaced 60.96 cm apart from the center ("o.c.").

For the mechanical fastening of the ceiling, 16-gauge staples with a size of 25.4 × 31.75 mm in increments of 17.78 cm o.c. along the joints and screws for dry plaster No. 6 with a length of 31.75 mm in increments of 30.48 cm o.ts. along the surface of the beams.

The ceiling was glued along the panel at an edge of approximately 38.1 mm. An edge was used on one side of the plane of the beams and along the edge on both sides of the beams at the gypsum joints.

The gypsum panel was attached with paper-glued edges parallel to the girder belts.

After the gypsum joints were glued with tape, measurements of the initial position were made. Then, the ceilings were coated with non-permeable paint, after which they sprayed a textured medium. Immediately after applying the textured medium, repeated measurements were made. Then Rockwool insulation was injected onto the top of the beams. After that, the third measurement was made. Over time, after the introduction of insulation, temperature and humidity increased. The set temperature was 32.22 ° C, and relative humidity 90%. These conditions were maintained for seven (7) days, while deflection was measured every morning and afternoon. After seven days, the room was opened and the temperature was brought to ambient temperature. Deflection measurements were performed for more than three (3) days, and then the tests were completed.

As shown in FIGS. 2 and 3, gypsum panels made in accordance with the present invention exhibit significant deflection resistance compared to other gypsum panels, and it was below the limit for deflection of 2.54 mm per 0.6096 m of panel length ( 4.17 mm per 1 meter of panel length), which is invisible to the human eye.

EXAMPLE 4

Tests for pulling nails from laboratory gypsum panels

Manufactured laboratory samples of typical paper-coated gypsum panels obtained in accordance with the present invention were compared with control panels for resistance to pulling nails. Nail pulling resistance is a measure of the combination of the strength of the gypsum core of the panels covering its paper sheets and the bond between paper and gypsum. In the test, the maximum force required to pull the nail with the cap through the panel was measured until mass cracking in the panel occurred, and the test was performed in accordance with AOIM standard C473-95.

Suspensions were prepared by mixing in a HOBART mixer for 40 seconds at an average speed: 3.0 kg of calcium beta-sulfate hemihydrate, 5 g of accelerator, as defined above, 10 g of LC-211 starch (acid-modified, pre-gelatinized dry ground wheat starch , introduced, as a rule, into the gypsum panel compositions of the previous technical solutions and supplied by Archer Daniels Midland Mill-ling Co.), 20 g of paper fiber finely chopped in a hammer mill, 3 liters of tap water, 0-6 g of TMPN and 0-30 g pre-desire inirovannogo cornstarch HCF-1000, available from Lauhoff Grain Co.

The suspensions thus obtained were poured onto pallets on top of the paper, and then laid on top of their paper to obtain samples of flat gypsum panels that were approximately 35.56 x 60.96 x 12.7 cm in size. The paper on one surface was multilayer with the outer layers of manila paper, and the paper on the other side was multilayer newsprint, both types of paper are commonly used for the manufacture of paper-coated gypsum panels in the panel industry. Then each panel was kept in an oven at a temperature of 176.67 ° C until it lost 25% of its weight, and it was moved to a [other] oven and kept at a temperature of approximately 44.44 ° C until its weight will not become permanent.

Then, the weight of the finished panel and the resistance to pulling the nail were measured. The results are shown in table 3.

The results of table 3 show that the panels made in accordance with the present invention have a higher total strength (resistance to pulling the nail) compared to the control panels.

EXAMPLE 5

Dimensional stability and constant resistance to gypsum models obtained on the production line

Paper-coated foam gypsum panels were fabricated on a typical full-scale production line on gypsum panel industrial equipment. The panels were made with different concentrations of the trimethaphosphate ion, and they were compared with control panels (made without the trimethaphosphate ion) for dimensional stability and resistance to constant deformation. With the exception of the introduction of the trimetaphosphate ion in the manufacture of some panels, the panels were made using methods and components typical of the methods and components in the production of gypsum panels in accordance with the previous technical solutions. Table 4 shows the components and their approximate composition in weight percent (expressed as relatively close ranges based on the weight of the calcined gypsum used).

In Table 4: the curing accelerator contained finely divided sugar coated calcium sulfate dihydrate particles as described in US Pat. No. 3,573,947, in which the accelerator was not heated during manufacture; starch was an acid-modified HI-BOND dry-milled starch purchased from Lauhoff Grain Co .; the dispersant was DILODLO, a naphthalene sulfonate purchased from GEO Specialty Chemicals, Ambler, PA; the paper fiber was finely chopped paper fiber in a hammer mill; cure retardant was VERSENEX 80, a gelling agent purchased from Walters & Rogers, Kirkland, Washington; the blowing agent was WITCOLATE1276, purchased from Witco Corp., Greenwich, Connecticut; sodium trimetaphosphate was purchased from Monsanto Co., St. Louis, Missouri; and the re-calcination inhibitor was CERELOSE 2001, a dextrose used to reduce re-calcination of the ends of panels during the drying process.

The panels were obtained on a continuous production line 1.22 m wide by: continuously introducing and mixing the components in a mixer to obtain an aqueous suspension (the blowing agent was used to form water-based foam in a separate foam system; then the foam was introduced into the suspension through a mixer); continuous distribution on a moving belt of a suspension on sheets of paper coating (facing paper); applying other sheets of paper coating (bottom paper) on top of the distributed suspension to obtain a panel 12.7 mm thick; when the hydration of calcium sulfate hemihydrate to form calcium sulfate dihydrate has continued sufficiently to obtain sufficient cure of the suspension so that the panel can be cut, cutting a moving panel to produce individual panels of 3.66 x 1.22 m and a thickness of 12.7 mm; and drying the panels in a heated multi-shelf oven. Then, the resistance to constant deformation of the panels was determined by measuring the deflection as described in Example 2, except that the test panels were parts of approximately 0.3048 × 3.66 m (the size of 0.3048 m corresponded to the direction of the production line, i.e. was parallel to the direction) cut from industrial panels. Deflection measurements were carried out after the panels were kept at an ambient temperature of 32.22 ° C and a relative humidity of 90% for 24, 48 and 96 hours. The results are shown in table 5 for samples of panels in accordance with the present invention with different concentrations of trimethaphosphate ion and control samples (0% sodium trimetaphosphate) obtained immediately before and after samples in accordance with the present invention.

The data in Table 5 show that the panels made in accordance with the present invention had a more intensively increasing deflection resistance as the concentration of PMSF (and thus a more intensively increasing resistance to constant deformation) increased than the control panels.

The deflection resistance obtained by using the compositions and methods in accordance with the present invention, in addition, is shown in figa. More specifically, Table 5A shows the deflection, i.e. dipping deflection arrow, in accordance with standard C 473-95 AOIM, obtained on a gypsum panel production line having dimensions of 0.3048 × 0.6096 m and the same composition as shown in Table 1 above. From Table 5A, the same the directionality of the deflection resistance in accordance with standard C 473-95 AOIM, as the directionality of the deflection resistance for longer panels (0.3048 × 3.66 m), as shown in Fig.5.

Both wetted gypsum panels obtained on the production line with a size of 3.66 × 1.22 m and finished dried panels with a size of 3.66 × 1.22 m were also measured (in accordance with C473-95 AOIM) to determine their shrinkage in width and length after drying. The greater the shrinkage of the panels, the less dimensional stability they are. The results are shown in table 6.

The data in table 6 show that the panels made in accordance with the present invention had higher dimensional stability than the control panels. With the addition of TMPF 0.04% or more, no shrinkage was found either in length or in width.

EXAMPLE 6

Resistance to deflection under conditions of humidification and condensation (gypsum panels obtained on the production line)

An additional test demonstrates the deflection resistance of the panels obtained using the compositions and methods in accordance with the present invention. More specifically, the gypsum panels obtained on the production line were tested in which the adjustable condensation made it possible to provide a vapor barrier placed between the ceiling panel and the joints. The procedure for this test was as follows. Small attic fences and rooms were erected. The attic space was isolated on its roof and side walls and kept chilled to obtain controlled condensation on the ceiling. The ceiling area was 2.44 × 2.44 m with rafters measuring 0.6096 × 2.44 m and a pitch of 60.96 cm relative to the center. The room space was fenced on its ceiling and side walls with a multi-layer vapor barrier [with a layer thickness] of 0.152 mm and they began to raise humidity in the room space to obtain controlled condensation on the ceiling.

Two panels of 1.22 × 2.44 m in size from the test material (one test item and one control) were attached next to the beams, with a 0.15 mm thick polyethylene vapor barrier located on top of the panel. The ends of the panel were not attached. Humidity was then increased in part of the room through a steam-emitting humidifier, while the attic temperature was lowered using a window air conditioner. The steam supply from the humidifier was controlled until constant condensation was obtained on the vapor barrier above the ceiling panel. Throughout the test, no attempt was made to maintain a constant temperature and humidity. Therefore, the results should be taken into account as a relative measure of the deflection resistance of the test and control products, and not an attempt to predict the magnitude of the deflection under certain controlled environmental conditions.

Then, the deflection of the ceiling was periodically measured in three places along the panel (in the middle of the span between each part of the beams), obtaining a total of six values of the deflection arrow per product in one test. In addition, the temperature of the attic and room fencing was recorded at each deflection measurement.

The theoretical conditions for the dew point based on known data (assuming room temperature constant and equal to 21.11 ° C) are given below.

The test was performed for eighteen days using the following material: a gypsum panel 12.7 mm thick obtained on the production line in accordance with the present invention and the Firecode gypsum panel type X described above, with a thickness of 15.875 mm. A panel made in accordance with the present invention has a significantly lower deflection than the control, i.e. Firecode gypsum board, type X, 15.875 mm thick, as described above.

In this test, in the middle of the span, a distributed load of 14.59 N / m was applied between each beam as soon as the 8th day arrived [of the test]. The application of this load significantly increased the deflection of the control panel, but significantly less affected the panel in accordance with the present invention. As shown in FIG. 4, the gypsum panels in accordance with the present invention had a deflection arrow that was significantly lower than that which is visible to the human eye, namely, less than 2.54 mm per 0.6096 m (4.17 mm per 1 m of panel) the length of the panel.

EXAMPLE 7

Resistance to pulling out a nail of a gypsum panel obtained on a production line

In a typical full-scale gypsum panel production line, other paper-coated cured gypsum panels were made. Panels with three concentrations of trimethaphosphate ion were made and compared for resistance to nail pulling with control panels (made without trimethaphosphate ion).

With the exception of the introduction of the trimetaphosphate ion in the manufacture of some of the panels, the panels were obtained using methods and components in accordance with the methods and components typical of the previous technical solutions. The components and their content in weight percent were the same as those shown in table 4. A method of manufacturing panels is described in example 5.

The resistance to pulling a nail was determined in accordance with the standard C473-95 AOIM. The results are shown in table 7 for samples in accordance with the present invention, obtained with different concentrations of trimethaphosphate ion and control samples (0% trimethaphosphate) obtained immediately before and after samples in accordance with the present invention.

The results are shown in table 7, obtained in the manufacture of panels made in accordance with the present invention, demonstrate a higher overall strength (resistance to pulling the nail) compared with the control panels.

EXAMPLE 8

The bond strength of paper with gypsum panel obtained on the production line

In a typical full-scale gypsum panel production line, other paper-coated cured gypsum panels were made. Panels with different concentrations of trimethaphosphate ion, pregelatinized starch and ungelatinized pre-starch were made and compared with control panels (obtained without trimethaphosphate ion or pre-gelatinized starch) to maintain the integrity of the connection between the core of the gypsum panels and their face paper coatings after being in conditions of extreme dampness and moisture.

With the exception of introducing the trimetaphosphate ion and pregelatinized starch and varying the concentration of ungelatinized pregel starch in the manufacture of some of the panels, the panels were prepared using methods and components in accordance with the methods and components typical of the preceding technical solutions. The components and their content in weight percent were the same as those shown above in table 4. A method of manufacturing panels is described in example 5.

The pregelatinized starch used in the tests was PCF1000, purchased from Lauhoff Grain Co. He pregelatinized starch was HI-BOND, an acid-modified non-gelatinized pregel dried starch purchased from Lauhoff Grain Co.

After manufacturing the panels on the production line, samples with dimensions of 10.16 × 16.51 cm were cut from them (10.16 cm corresponds to the direction of the production line). Each of these small panel samples was then conditioned by keeping the entire outer surface of the paper coating on the front side in contact with a completely water-soaked cloth for 6 hours at a temperature of 32.22 ° C and a relative humidity of 90% of the environment, and then the wet cloth was removed and allowed the panel samples to dry slowly in the same environment until their weight became constant (usually about 3 days). Then, on the back surface of the panel samples at a distance of 63.5 mm from one of the edges measuring 152.4 mm and parallel to it, one narrow groove was made with a depth of 3.175 mm. After that, the core of the panel was clamped along the groove, without damage or squeezing of paper on the front side of the panel, and then most of the panel sample (63.5x152.4 mm) was pressed down under pressure, while the smaller part was held motionless and horizontal from its side the back surface, in an attempt to force the paper on the front of the panel to peel off from most of the panel. The force was increased until there was a complete separation of the two parts of the panel. The face of the panel was then checked to determine how much of its surface the paper had peeled off completely from the core (defined as “clean peeling”). This percentage area is shown in Table 8 as “% Communication Disruption”.

The data in table 8 show that after staying in conditions of excessive wetting regarding the problem of breaking the bond of the paper with the core of the panel: PMSC increases the problem; increasing the concentration of typical pre-gelatinized starch (HI-BOND) does not alleviate the problems; the introduction of pregelatinized starch (PCF1000) facilitates or eliminates the problem.

EXAMPLE 9

Processing products from calcium sulfate dihydrate after manufacture

In some preferred alternative embodiments of the present invention, the calcium sulfate dihydrate casting is treated with an aqueous solution of trimetaphosphate ion so as to obtain a sufficiently uniform distribution of the trimetaphosphate ion in the calcium sulfate dihydrate casting to increase strength, constant deformation resistance (e.g., deflection resistance), and dimensional stability containing cured gypsum products after repeated drying. More specifically, it has been found that treating a casting of calcium sulphate dihydrate with a trimethaphosphate ion increases strength, resistance to constant deformation (e.g., deflection resistance) and dimensional stability to a degree similar to that achieved using options in which the trimethaphosphate ion is added to calcined gypsum . Thus, in the embodiment in which the trimethaphosphate ion is introduced into the cured gypsum, it offers new compositions and methods for producing improved gypsum-containing products, including but not limited to boards, panels, tiles, gypsum / cellulose fiber composites, etc. Therefore, any gypsum-based product that requires tight control of deflection resistance will benefit from using this embodiment of the present invention. This treatment also increases the strength of the gypsum cast by approximately 15%. Trimetaphosphate ions can be introduced into gypsum castings in an amount of 0.04-2.0% (relative to the weight of gypsum) by spraying or impregnating with an aqueous solution containing trimethaphosphate ion, and then re-drying the gypsum castings.

Two methods of processing hardened gypsum products after their manufacture are as follows:

In both of the above methods, the aqueous solution of the trimetaphosphate ion is preferably added in an amount and so that it is sufficient to obtain a concentration of approximately 0.04-0.16 wt.% (Relative to the weight of calcium sulfate dihydrate) of the trimetaphosphate ion in the cast of calcium sulfate dihydrate .

The effect of reducing the deflection boom (i.e., deflection resistance) when using the first method described above is shown in FIG. Five (5) panels were fabricated and tested for deflection deflection arrows, as shown in FIG. 5. The dried panels weighed from 750 to 785 g. No solutions were added to the control panels after the final curing and drying of the gypsum cast. The panel, referred to as the “water only” panel [Fig. 5], contained only water introduced by spraying onto the cured and dried gypsum cast, and then was re-dried. The panel, referred to as the “TMPF solution” panel, contained 1% by weight of trimethaphosphate ion in an aqueous solution introduced by spraying onto the hardened and dried gypsum cast, and then was re-dried. The panel, called the "Gypsum-TMPN" panel, contained an aqueous solution saturated with gypsum and containing 1% by weight of trimethaphosphate ion, introduced by spraying onto the cured and dried gypsum cast, and then re-dried. In general, it is preferable to have a solution to be sprayed containing a concentration of trimethaphosphate ion in the range of 0.5 to 2% by weight. The final amount of trimethaphosphate ion both in the panel with the TMPN solution and the Gypsum-TMPN solution was 0.2% with respect to the weight of the gypsum cast used to produce the gypsum cast and 0.17% with respect to the weight of the finished panel containing hardened gypsum .

EXAMPLE 10

High salt processing

Other embodiments of the present invention relate to gypsum-containing cured products made from mixtures of materials based on calcium sulfate and water, containing high concentrations of chloride ions or their salts (namely, at least 0.015 wt.% With respect to the weight of the material based on calcium sulfate in mixtures, usually more than 0.02-1.5 wt.%). Chloride ions or their salts can be impurities in the materials themselves based on calcium sulfate or in water (for example, in seawater or in subsoil water containing brine) used in a mixture that until the present invention could not be used to obtain stable, containing hardened gypsum products, because they caused problems such as bloating, damage to the bond with the paper, burn out of the ends, low resistance to constant deformation, low strength and low dimensional stability.

The test results shown in table 9 relate to gypsum panels made and processed in the same manner as described in example 2, except that various amounts of chloride ion were introduced into the mixture along with different amounts of trimethaphosphate ion. Tests to determine the deflection arrows were performed in the same manner as described in example 2.

The test results shown in table 10 show that treatment with the trimethaphosphate ion allows the use of mixtures containing high concentrations of chloride ions or their salts. The panels were made and processed in the same manner as in Example 4, except that a different amount of chloride ion was introduced into the mixture, along with different amounts of trimethaphosphate ion. The integrity of the connection between the core of the gypsum panel and its paper face coating was tested in the same manner as described in example 8.

Table 11 shows the results of treating with a chloride ion of trimetaphosphate and PCF starch 1000 materials with a high content of chloride (from 0.08 to 0.16 wt.% Sodium chloride in the finishing gypsum) of panels that were made differently and processed in a similar way, as described in the example 5. As shown in table 11, the treatment provides an increase in strength when pulling a nail (measured in the same way as in example 4, namely, according to the standard C473-95 AOIM) and similar characteristics of the connection (measured in the same way as in example 8) compared with control panels, not with ERZHAN sodium chloride. In addition, treatment with the trimethaphosphate ion provides a significant improvement in deflection during wetting even with up to 0.3 wt.% Chloride added.

Table 12 shows the results of treatment of trimetaphosphate ion and PCF starch 1000 with materials even with a higher (than in table 11) chloride content (0.368% sodium chloride in the finishing gypsum) of panels that were made differently and processed in a similar manner as described in example 5 As shown in table 12, the treatment provides an increase in the strength when pulling a nail (measured in the same way as in example 4, namely, according to the standard C473-95 AOIM) and similar bond characteristics (measured in the same way as in example 8) compared to control panels not containing sodium chloride.

EXAMPLE 11

Treatment of calcined gypsum with various improvers

In the examples of the previously described preferred embodiments, the improving agent is the trimethaphosphate ion. However, in general, any improving agents that meet the general definition of improving agents described above will provide effective results (for example, increased resistance to permanent deformation) when processing calcined gypsum. As a rule, suitable improving agents include concentrated phosphoric acids, each of which contains 2 or more structural elements of phosphoric acids; and salts or ions of concentrated phosphates, each of which contains 2 or more structural units of phosphates.

Specific examples of such improving agents include the following acids or salts, or their anionic groups: sodium trimetaphosphate having the formula of a molecule (NaPO ₃ ) ₃ , sodium hexametaphosphate having 6-27 repeating phosphate structural elements and the formula of a molecule Na _{n + 2} P _n O _{3n + l} , where n = 6-27, tetracal potassium pyrophosphate having the formula of the molecule K ₄ P ₂ O ₇ , tri-sodium dipotassium tripolyphosphate having the formula of the molecule Na ₃ K ₂ P ₃ O ₁₀ sodium tripolyphosphate having the formula of the molecule Na ₅ P ₃ O ₁₀ tetrasodium polyphosphate having the formula of a molecule of Na ₄ P ₂ O ₇ , trimetaphosphate alumin oi having the formula of an Al (PO ₃ ) ₃ molecule, sodium acid pyrophosphate having the formula of a Na ₂ H ₂ P ₂ O ₇ molecule, ammonium pyrophosphate having 1000-3000 repeating structural elements and the formula of an (NH4) _{n + 2} P _n molecule) 3 _{n + 1} , where n = 1000-3000, or polyphosphoric acid having 2 or more repeating structural elements of phosphoric acid and the formula of the molecule H _n + ₂ P _n O _{3n + l} , where n is 2 or more.

The results of the use of such improving agents for the treatment of calcined gypsum are shown in tables 13, 14 and 15.

Table 13 shows the results of using various improving agents for processing calcined gypsum in the manufacturing process of gypsum panels and cubes. The panels were made and processed in the same manner as described in example 2. The cubes were made and processed in the same way as described in example 1. Except for two cases, various enhancement agents were used than the trimethaphosphate ion. The deflection boom after wetting was measured in the same manner as described in example 2. The compressive strength was measured in the same manner as described in example 1.

Table 14 shows the results of the use of polyphosphoric acid for processing calcined gypsum in the manufacturing process of gypsum panels and cubes. The panels were made and processed in the same manner as described in example 2. The cubes were made and processed in the same way as described in example 1. Except for two cases, various enhancement agents were used than the trimethaphosphate ion. The deflection boom after wetting was measured in the same manner as described in example 2. The compressive strength was measured in the same manner as described in example 1.

Table 15 shows the results of using aluminum polyphosphate (“PFA”) for processing calcined gypsum in the process of manufacturing gypsum panels and cubes. The panels were made and processed in the same manner as described above in Example 2. The cubes were made and processed in the same manner as described above in Example 1. With two exceptions, various enhancement agents were used than the trimethaphosphate ion. The deflection boom after wetting was measured in the same manner as described above in Example 2. The compressive strength was measured in the same manner as described above in Example 1.

The results given in tables 13, 14 and 15 show that all tested materials that meet the above definition of improving agents, when they are used to process calcined gypsum in the manufacture of hardened gypsum-containing products, contribute to their significantly higher resistance to constant deformation compared to control samples.

EXAMPLE 12

Treatment of castings from calcium sulfate dihydrate with various improving agents

In general, any improving agents that meet the general definition of improving agents described above will provide effective results (for example, increased resistance to constant deformation and increased strength) when processing castings from calcium sulfate dihydrate. Typically, suitable enhancement agents include: phosphoric acids, each of which contains 1 or more structural elements of phosphoric acids; and salts - or ions of concentrated phosphates, each of which contains 2 or more structural elements of phosphates and monobasic salts or monovalent ions of orthophosphates.

The results of using improving agents for processing castings of calcium sulfate dihydrate are shown in table 16.

Table 16 shows the results of using various materials in varying amounts to process dried calcined gypsum in the form of panels and cubes. The panels were made and processed in the same manner as described in example 2, and then processed as described in example 9. The cubes were made in the same way as described in example 1 and further processed in the same manner as described in example 9. For with the exception of two cases, various enhancing agents were used than the trimethaphosphate ion. The deflection boom after wetting was measured in the same manner as described in Example 2. The compressive strength was measured in the same manner as described above in Example 1.

The results shown in table 16 show that, within the framework of the above definition, improving agents, when used to treat cured and dried calcium sulfate dihydrate products, provide them with significantly higher resistance to constant deformation and significantly higher strength compared to control samples.

It will be understood by those skilled in the art that in the manufacture of gypsum-containing cured products in accordance with the present invention, a wide pH range, i.e. equal to or higher than 3.5. In the manufacture of gypsum panels in accordance with the present invention, the working pH range is preferably from about 5.0 to 9.0, and more preferably from about 6.5 to 7.5.

EXAMPLE 13

Overcoming Slowdown and Strength Reduction

In the pre-treatment for curing the calcium sulfate-based material of the present invention, it was further found that some improving agents slow down the hydration rate during the formation of the set gypsum and adversely affect the strength of the set gypsum-containing product. It was found that the slowdown and adverse effect on strength can be reduced or even overcome by introducing the accelerator into the mixture in an appropriate amount and in an appropriate manner. This is shown in Table 17. The suspension was prepared in accordance with Example 1, and sodium hexametaphosphate was used as the improving agent. Part of the suspension was tested using AOIM standard C 472 to determine the time required to achieve 98% hydration of the set gypsum. Another part of the suspension was used to make cubes in accordance with example 1 to determine the compressive strength. For these purposes, any of the known materials that can increase the rate of formation of set gypsum can be used. For this, the preferred accelerator is preferably the previously defined accelerator described in Example 1.

EXAMPLE 14

Plaster Casting

In addition, it was found that in accordance with the principles of the present invention, it is possible to obtain gypsum panels of the desired shape. Prior to the present invention, the shape of a completely flat gypsum panel was changed, as a rule, by wetting the panel with water to soften it and giving it more flexibility, and then changing the shape of the panel as necessary, and holding the panel thereafter until it dried. However, this prior technology increases the problems in many industries and equipment, since the humidification required to soften the panel and give it more flexibility so that it can be shaped, takes a considerable amount of time, namely at least one hour or more, and often requires twelve hours. In addition, prior technology is not well suited to make it easier to shape a panel. If the panel is not softened enough, then there are difficulties in giving it the desired shape. Namely, more effort is required to change the shape of the panel, as necessary, and if too much force is applied, the panel may be destroyed. Thus, there is a great need to develop methods and compositions that would reduce the wetting time and facilitate the process of shaping the gypsum panel.

According to a preferred embodiment of the present invention, for example, an aqueous chloride solution containing any enhancing agent (as described above in the examples and a brief description of the present invention) can be sprayed onto a flat gypsum panel to soften the panel and give it more flexibility. Then, a softened and more flexible panel can be easily shaped to fit with less effort than with prior technologies, and the modified panel, after drying, should retain its desired shape due to the beneficial effect of the improving agent, especially resistance to constant deformation.

It was found that, for example, absolutely flat gypsum panels with a thickness of 7.938, 9.525 and 12.70 mm can be shaped by softening the gypsum panel by spraying a solution of chloride salt or a mixture of solutions of various chloride salts (such as sodium chloride, calcium chloride) , magnesium chloride, potassium chloride, aluminum chloride, etc.) containing the improving agent described above. To achieve the most preferred results, a wetting agent (such as the surfactant Tergitol NP-9, supplied by Union Carbide Chemical & Plastic Company, Inc .; Neodol® 1-7 and Neodol® 1-5, supplied by Shell Chemical Company, and Iconol TDA-6 and Iconol DA-6, supplied by BASF Corporation) can be used to perform quick and effective moisturizing treatments. Starch (such as Stapol 580 and Stapol 630, supplied by A.E. Staley Manufacturing Company) can be used to improve the bond of the paper to the core and the strength of the modified shaped panel. An antifoam agent can be added to the saline if the formation of foam causes problems due to the foaming properties of the wetting agents.

In a preferred embodiment, the saline solution described above is applied to one side of the panel, while the other side is not treated to maintain tear resistance on the untreated side of the panel to prevent destruction of the panel in the process of changing its shape.

The processed panel may, for example, be a gypsum panel of any type with a paper coating, with any typical additives and gypsum compositions in such a panel. In a preferred embodiment, the panel contains internal reinforcing materials, such as discrete fibers (for example, glass, paper and / or synthetic fibers).

In accordance with the present invention, you can change the shape of gypsum panels of any size and thickness. In accordance with a preferred embodiment of the present invention, the shape of the paper-coated gypsum panels 7.938, 9.525 and 12.70 mm thick was changed by treating one side of the panel with an “easy to bend” solution containing (in relation to the total weight of the solution) 0.05 wt.% Sodium chloride , 0.05 wt.% Sodium trimetaphosphate, 0.05 wt.% Surfactant Tergitol NP-9 (wetting agent) and 0.025 wt.% Stapol 580 (modified corn starch). USG SHEETROCR® paper coated wall plaster panels of various thicknesses of 10.16 x 10.16 cm in size were sprayed with the most preferred bending solution, described above, in an appropriate manner to allow the panel to be impregnated with a thickness of 7.938 mm. 9.525 mm 1.814 kg facilitating the bending of the mortar and panels 12.7 mm thick 2.722 kg facilitating the bending of the mortar. The tests were carried out by treating one side of the wall gypsum panel, and the results were the same, regardless of whether the front side or the back side was processed. The results are shown in table 18.

As shown in table 18, after processing in accordance with the present invention, the shape of the wall gypsum panel can be changed as necessary. As shown, the required exposure time between the processing of the bending-facilitating solution and the flexible panel was minutes rather than hours that were required using the previous technical solutions.

The minimum radius of curvature (i.e., a measure of the degree of achievable bend; the smaller the radius, the greater the degree of achievable bend) are shown in Table 18 for each panel thickness. In each case, the minimum radius is much smaller than can be obtained using known technologies. As a rule, panels can also be bent in the direction of a generally weaker width.

The preferred method of processing and installing gypsum panels at the installation site is as follows.

Take chloride salts, starch, an improving agent, a wetting agent and the required amount of water

↓

Gently mix them for a uniform, easy-to-bend solution

↓

Spray the bending solution on one side of the gypsum board.

Wait 5-25 minutes

↓

Bend the gypsum panel to the desired curvature, install the panel and allow it to dry in the wild.

Suitable composition in relation to the weight of the solution: 0.05-1% chloride salt; 0.05-0.3% wetting agent; 0.05-0.5% improving agent; 0.025-0.2% starch. In addition, if necessary, an anti-foaming agent (for example, FoamMaster supplied by Henkel Corporation) in an amount of 0.01-0.05% based on the weight of the solution may be added to the bending aid.

Chloride salt, wetting and improving agents can be introduced into the panel separately, together or one with the other, at any time before drying the panel to provide advantages of the present invention.

The present invention is described in detail with specific reference to some of its preferred options, however, it should be borne in mind that changes and modifications can be made within the essence and scope of the claims of the present invention.

Claims (52)

1. A method of manufacturing a cured gypsum-containing product having increased resistance to constant deformation, comprising obtaining a mixture of a material based on calcium sulfate, water, an accelerator and one or more improving agents selected from the group consisting of one or more of the following acids or salts, or anionic groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphate, tetracal potassium pyrophosphate, trisodium dipotassium tripolyphosphate, tetrasodium pyrophosphate, aluminum trimetaphosphate, acid pyroph sodium sulfate, ammonium polyphosphate having 1000-3000 repeating structural elements of phosphate, or polyphosphoric acid having 2 or more repeating structural elements of phosphoric acids, and the mixture contains from about 0.015 to about 1.5 wt.% (by weight of sulfate-based material calcium mixture) of chloride ions or their salts, and maintaining the mixture under conditions sufficient to convert the material based on calcium sulfate into a material based on hardened gypsum with interconnected cells of the crystal lattice ki, while the improving agent or agents are introduced into the mixture in such an amount that the gypsum-containing product has a higher resistance to permanent deformation than if the improving agent was not introduced into the mixture, and the accelerator is introduced in such an amount that the gypsum-containing gypsum the product had a higher strength than if the accelerator was not introduced into the mixture. 2. The method according to claim 1, wherein the concentration of the improving agent in the mixture is from about 0.004 to 2.0% by weight of calcium sulfate-based material. 3. The method according to claim 1, wherein the concentration of the improving agent in the mixture is from about 0.04 to 0.16% by weight of calcium sulfate based material. 4. The method according to claim 1, wherein the concentration of the improving agent in the mixture is approximately 0.08% by weight of calcium sulfate-based material. 5. The method according to claim 1, wherein the mixture further comprises pre-gelatinized starch. 6. The method according to claim 1, wherein the material based on calcium sulfate contains one or more of calcium sulfate anhydride, calcium sulfate hemihydrate or calcium ions and sulfate. 7. The method according to claim 1, wherein the calcium sulfate-based material comprises calcium sulfate hemihydrate. 8. The method according to claim 7, in which the improving agent includes one or more of the following salts or their anionic groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphates, and ammonium polyphosphate having 1000-3000 repeating structural elements of phosphates. 9. The method according to claim 1, wherein the mixture contains 0.02-1.5% (by weight of the material based on calcium sulfate in the mixture) of chloride ions or their salts. 10. Gypsum-containing cured product made by the method described in claim 1. 11. A gypsum panel having increased deflection resistance, comprising a core of laminate between coating sheets, in which the core contains gypsum with interlocking cells with a crystal lattice, the panel being made by a method comprising preparing or placing a mixture between coating sheets, the mixture comprising material on based on calcium sulfate, water, an accelerator and one or more improving agents selected from the group consisting of one or more of the following acids or salts, or their anio groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphate, tetracal potassium pyrophosphate, trisodium dipotassium tripolyphosphate, tetrasodium pyrophosphate, aluminum trimetaphosphate, sodium acid pyrophosphate, ammonium polyphosphate having 1000-3000 repeating phosphate structural elements, or polyphosphate an acid having 2 or more repeating structural elements of phosphoric acids, the mixture additionally containing from about 0.015 to about 1.5% (by weight of the material based on calcium sulfate in the mixture) chlorides or their salts, and maintaining the mixture under conditions sufficient to convert the calcium sulfate-based material into gypsum with interconnected cells of the crystal lattice, while the improving agent or agents are introduced into the mixture in such an amount that the gypsum panel has a higher deflection resistance than if the enhancing agent was not introduced into the mixture, and the accelerator was introduced in such an amount that the gypsum panel had a higher strength than if the accelerator was not introduced into the mixture. 12. The gypsum panel according to claim 11, in which the concentration of the improving agent in the mixture is from about 0.004 to 2.0% by weight of calcium sulfate-based material. 13. The gypsum panel according to claim 11, in which the concentration of the improving agent in the mixture is from about 0.04 to 0.16% by weight of calcium sulfate-based material. 14. The gypsum panel according to claim 11, in which the concentration of the improving agent in the mixture is approximately 0.08% by weight of calcium sulfate-based material. 15. The gypsum panel according to claim 11, in which the material based on calcium sulfate contains one or more of calcium sulfate anhydride, calcium sulfate hemihydrate or calcium ions and sulfate. 16. The gypsum panel of claim 11, wherein the calcium sulfate-based material contains calcium sulfate hemihydrate. 17. The gypsum panel according to clause 16, in which the enhancing agent includes one or more of the following salts or their anionic groups: sodium trimetaphosphate having 6-27 repeating structural elements of phosphates, and ammonium polyphosphate having 1000-3000 repeating structural elements of phosphates. 18. The gypsum panel according to claim 11, in which the mixture contains 0.02-1.5% (by weight of the material based on calcium sulfate in the mixture) of chloride ions or their salts. 19. The gypsum panel according to claim 11, in which the mixture further comprises pre-gelatinized starch. 20. The gypsum panel according to claim 19, in which the concentration of pregelatinized starch in the mixture is from about 0.08 to 0.5% by weight of calcium sulfate based material. 21. The gypsum panel according to claim 19, in which the concentration of pregelatinized starch in the mixture is from about 0.16 to 0.4% by weight of calcium sulfate based material. 22. The gypsum panel according to claim 19, in which the concentration of pregelatinized starch in the mixture is approximately 0.3% by weight of calcium sulfate-based material. 23. The gypsum panel according to claim 11, in which the core contains pores uniformly distributed in it, and the mixture further comprises water-based foam. 24. The gypsum panel of claim 23, wherein the water-based foam is obtained from a blowing agent or a mixture of blowing agents having the formula CH ₃ (CH ₂ ) _x CH ₂ (OCH ₂ CH ₂ ) _for OSO ₃ Θ M⊕, where x is a number from 2 to 20; y represents a number from 0 to 10 and is 0 at least 50 wt.% blowing agent or a mixture of blowing agents; M is a cation. 25. The gypsum panel according to paragraph 24, in which y = 0 in 86-99 wt.% Blowing agent or a mixture of blowing agents. 26. The gypsum panel according to claim 11, in which the mixture further comprises pre-gelatinized starch and water-based foam. 27. A method of manufacturing a modified form gypsum panel, comprising preparing a homogeneous aqueous solution comprising water, at least one chloride salt, a wetting agent and one or more improving agents selected from the group consisting of phosphoric acids, each of which contains 1 or more structural phosphoric acid elements; salts or ions of concentrated phosphates, each of which contains 2 or more structural elements of phosphates and monobasic salts or monovalent orthophosphate ions, and applying a homogeneous aqueous solution to the gypsum panel in an amount sufficient to soften the gypsum panel to facilitate changing the shape of the gypsum panel, changing the shape of the gypsum panels, as necessary, and drying the gypsum panel to obtain a gypsum panel of a modified form, with chloride salt, an improving agent or agents and wetting agents applied It is sufficient to ensure that the form of the gypsum panel changes in a short time and a higher resistance to constant deformation of the changed gypsum panel is achieved than if the enhancing agent and wetting agent were not applied to the gypsum panel. 28. The method according to item 27, in which the applied solution, in addition, contains pre-gelatinized starch. 29. The method according to item 27, in which the applied solution, in addition, contains an anti-foam agent. 30. The method according to item 27, in which the applied solution has a concentration of chloride of 0.05-1.0% by weight of the solution. 31. The method according to item 27, in which the applied solution has a concentration of a wetting agent of 0.05-0.3% by weight of the solution. 32. The method according to item 27, in which the applied solution has a concentration of an improving agent of 0.05-0.5% by weight of the solution. 33. The method according to p, in which the applied solution has a starch concentration of 0.025-0.2% relative to the weight of the solution. 34. The method according to clause 29, wherein the applied solution has a concentration of anti-foam agent of 0.01-0.05% by weight of the solution. 35. The method according to item 27, in which the gypsum panel is a panel with a paper coating. 36. The method according to item 27, in which a homogeneous water-based solution is applied only on one side of the gypsum panel. 37. The gypsum panel of a modified form made by the method according to item 27. 38. A method of manufacturing a modified form of gypsum board, comprising applying to a gypsum panel a homogeneous water-based solution containing water and a wetting agent, applying to a gypsum panel a homogeneous water-based solution containing water and at least one chloride salt, applying to a gypsum panel before performing its drying of a solution containing one or more improving agents selected from the group consisting of phosphoric acids, each of which contains 1 or more structural elements of phosphoric acids slot salts or ions of concentrated phosphates, each of which contains 2 or more structural elements of phosphates and monobasic salts or monovalent ions of orthophosphates, changing the shape of the gypsum panel, as necessary, and drying the gypsum panel to obtain a gypsum panel of a changed shape, the chloride salt improving agent or the agents and wetting agents are applied to the gypsum board in an amount sufficient to provide a change in the shape of the gypsum board in a short time and higher resistance to constant deformation and a gypsum panel of a changed shape than if an improving agent and a wetting agent were not applied to the gypsum panel. 39. The method according to § 38, wherein a solution containing pre-gelled starch is also applied to the gypsum panel before it is dried. 40. The method according to § 38, wherein a solution containing an anti-foam agent is also applied to the gypsum panel before it is dried. 41. The method according to § 38, in which the applied solution containing chloride salt has a concentration of chloride salt of 0.05-1.0% by weight of the solution. 42. The method according to § 38, in which the applied solution containing a wetting agent, has a concentration of a wetting agent of 0.05-0.3% by weight of the solution. 43. The method according to § 38, wherein the applied solution containing the improving agent has a concentration of the improving agent 0.05-0.5% by weight of the solution. 44. The method according to § 39, wherein the applied solution containing starch has a starch concentration of 0.025-0.2% by weight of the solution. 45. The method according to p, in which the applied solution containing an anti-foam agent, has a concentration of anti-foam agent of 0.01-0.05% by weight of the solution. 46. The method according to § 38, wherein the gypsum panel is a paper-coated panel. 47. The method according to § 38, wherein the chloride salt, the improving agent or agents and the wetting agent are applied to only one side of the gypsum board. 48. The gypsum panel of a modified form made by the method according to clause 38. Priority on points: 07/30/1998 PP 1-9, 13-20, 24-31; 08.21.1998 10-12, 21-23; 08.21.1998 10-12, 21-23; 02.16.1999 PP 32-48.

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