Plasterboard manufacturing method and plasterboard
By integrating recycled calcium sulfate materials in a controlled manner, the method addresses the environmental impact and quality issues in plasterboard manufacturing, maintaining production efficiency and product quality.
Patent Information
- Application Number
- JP2024569748
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-10-13
- Filing Date
- 2023-07-26
- Publication Date
- 2025-07-25
AI Technical Summary
Existing gypsum-based plasterboard manufacturing processes have a significant environmental impact and do not effectively utilize recycled calcium sulfate materials, which often contain impurities that affect the manufacturing process and product quality.
A method involving the mixing of recycled and non-recycled calcium sulfate materials in a 1:1 ratio, followed by grinding and firing, to form a solidifiable slurry for plasterboard production, with controlled particle sizes and impurity levels, ensuring desirable hydration properties and reduced environmental footprint.
The method maintains the quality and production efficiency of plasterboards while significantly reducing environmental impact, achieving equivalent or improved manufacturing rates and product characteristics.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing plasterboard. The present invention further relates to plasterboard and the use of plasterboard.
Background Art
[0002] Gypsum occurs naturally as a raw material in the form of calcium sulfate dihydrate (CaSO4·2(H2O)). Gypsum-containing products such as plasterboard are manufactured by forming a mixture of calcined gypsum or dehydrated gypsum, i.e., calcium sulfate hemihydrate (CaSO4·0.5(H2O)) and water to form a solidifiable slurry, and then casting it into a predetermined shape. Calcium sulfate hemihydrate reacts with water, rehydrates to dihydrate crystals, and then cures or dries to a solid state.
Summary of the Invention
Problems to be Solved by the Invention
[0003] Gypsum products are commonly found throughout buildings because of their versatility, desirable mechanical properties, and potential for a high level of finish. Therefore, it is desirable to manufacture gypsum products with reduced environmental impact.
Means for Solving the Problems
[0004] According to a first aspect of the present invention, there is provided a method for manufacturing plasterboard, comprising the steps of mixing at least one recycled calcium sulfate material and at least one non-recycled calcium sulfate material to form a particle mixture, mixing at least the particle mixture and water to form a solidifiable slurry, and drying the solidifiable slurry to form a plasterboard, wherein the ratio of the recycled calcium sulfate material to the non-recycled calcium sulfate material in the particle mixture is at least 1:1, and the method further comprises the step of firing the particle mixture before mixing the particle mixture with water to form a solidifiable slurry.
[0005] In this way, a method for manufacturing plasterboard with reduced environmental impact is provided while maintaining favorable manufacturing and final product characteristics.
[0006] Here, to avoid ambiguity, it is understood that calcium sulfate materials, especially recycled calcium sulfate materials, can be impurities. Therefore, calcium sulfate materials should be understood to contain calcium sulfate in at least one form of its dihydrate, hemihydrate, or anhydrous form for the most part, but may also contain impurities.
[0007] Such impurities can include, but are not limited to, paper, glass fibers, fluidizing agents, water-resistant agents, and other components that are often introduced into the plasterboard in the manufacturing process. As understood, these impurities will also be incorporated into the recycled calcium sulfate material when present in, for example, the plasterboard. Therefore, when discussing the ratio of recycled calcium sulfate material to non-recycled calcium sulfate material, it is correct to compare the relative weights of both materials including the impurities.
[0008] Preferably, the method includes a step of grinding the particle mixture before mixing the particle mixture with water to form a solidifiable slurry. In this way, the method can reduce the particle size in the particle mixture, and as a result, improve and / or accelerate the entire manufacturing process.
[0009] Preferably, the average residence time of the particles in the particle mixture in the grinder is less than 75 seconds. More preferably, the average residence time of the particles in the particle mixture in the grinder is less than 60 seconds. Most preferably, the average residence time of the particles in the particle mixture in the grinder is less than 45 seconds.
[0010] Preferably, the Blaine value of the ground calcined material is less than 8000 cm 2 / g. More preferably, the Blaine value of the ground calcined material is less than 7000 cm 2less than / g. Even more preferably, the Blaine value of the pulverized and fired material is 6000 cm 2 / g or less. In this way, the particles in the fired mixture can have desirable hydration properties and / or a desirable water requirement.
[0011] Preferably, after firing, the particle mixture contains less than 20% by weight of calcium sulfate anhydride. Preferably, after firing, the particle mixture contains less than 16% by weight of calcium sulfate anhydride. Preferably, after firing, the particle mixture contains less than 10% by weight of calcium sulfate anhydride. By producing such a particle mixture, the process and / or the plasterboard can be improved.
[0012] Preferably, at least one non-recycled calcium sulfate material contains calcium sulfate hemihydrate. In some embodiments, at least one non-recycled calcium sulfate material consists of calcium sulfate hemihydrate. Preferably, at least one calcium sulfate material contains calcium sulfate dihydrate. In some embodiments, at least one non-recycled calcium sulfate material consists of calcium sulfate dihydrate.
[0013] Preferably, at least one recycled calcium sulfate material contains calcium sulfate hemihydrate. In some embodiments, at least one recycled calcium sulfate material consists of calcium sulfate hemihydrate. Preferably, at least one recycled calcium sulfate material consists of calcium sulfate dihydrate. In some embodiments, at least one recycled calcium sulfate material contains calcium sulfate dihydrate.
[0014] In some embodiments, the non-recycled calcium sulfate material and / or the recycled calcium sulfate material contain both calcium sulfate hemihydrate and calcium sulfate dihydrate.
[0015] Preferably, the recycled calcium sulfate material contains paper. More preferably, the recycled calcium sulfate material contains 2.2 wt% or less of paper, or 2 wt% or less of paper. Even more preferably, the recycled calcium sulfate material contains 1.7 wt% or less of paper, or 1.6 wt% or less of paper, or 1.5 wt% or less of paper. Even more preferably, the recycled calcium sulfate material contains 1.2 wt% or less of paper, or 1.0 wt% or less of paper. Even more preferably, the recycled calcium sulfate material contains 0.84 wt% or less of paper, or 0.7 wt% or less of paper, or 0.5 wt% or less of paper. Most preferably, the recycled calcium sulfate material contains 0.4 wt% or less of paper, or 0.2 wt% or less of paper. When the paper content of the recycled calcium sulfate material is as described, the recycled calcium sulfate material may have desirable hydration properties and / or water demand properties.
[0016] Preferably, the particle mixture contains 2.2 wt% or less of paper. More preferably, the particle mixture contains 2 wt% or less of paper, or 1.7 wt% or less of paper, or 1.6 wt% or less of paper, or 1.5 wt% or less of paper. Even more preferably, the particle mixture contains 1.2 wt% or less of paper. Even more preferably, the particle mixture contains 1 wt% or less of paper, or 0.84 wt% or less of paper. Even more preferably, the particle mixture contains 0.7 wt% or less of paper. Even more preferably, the particle mixture contains 0.5 wt% or less of paper, or 0.4 wt% or less of paper. Most preferably, the particle mixture contains 0.2 wt% or less of paper. When the paper content of the particle mixture is as described, the particle mixture may have desirable hydration properties and / or water demand properties.
[0017] Preferably, the method manufactures equivalent plasterboards at a rate exceeding 80% of the rate of an equivalent process in which the mixture does not contain recycled calcium sulfate material. More preferably, the method manufactures equivalent plasterboards at a rate exceeding 90% of the rate of an equivalent process in which the mixture does not contain recycled calcium sulfate material. In this way, the desirable properties of the equivalent process are maintained, and calcium sulfate products such as plasterboards have substantially the same properties as equivalent products manufactured by the equivalent process.
[0018] Preferably, the firing furnace throughput rate of the method is more than 80% of the throughput rate of an equivalent process in which the mixture does not contain recycled calcium sulfate material, and the plasterboard manufactured by the method is equivalent to that manufactured by the equivalent process. More preferably, the firing furnace throughput rate of the method is more than 90% of the throughput rate of an equivalent process in which the mixture does not contain recycled calcium sulfate material, and the plasterboard manufactured by the method is equivalent to that manufactured by the equivalent process. In this way, the desirable properties of the equivalent process are maintained.
[0019] Preferably, the method includes the step of adding a fluidizing agent to the curable slurry. Preferably, the fluidizing agent is added in an amount of 1% by weight or less of the dry weight of the calcium sulfate material. Preferably, the fluidizing agent is added in an amount of 0.1% by weight or more of the dry weight of the calcium sulfate material.
[0020] Preferably, the manufactured plasterboard has a density of 3 960 kg / m or less. Preferably, the manufactured plasterboard has a density of 3 760 kg / m or less. Preferably, the plasterboard has a density of 3 520 kg / m or more. Preferably, the plasterboard has a density of 3 680 kg / m or more. Preferably, the manufactured plasterboard has a thickness of 12.5 mm or less.
[0021] According to a second aspect of the present invention, there is provided a plasterboard comprising a recycled calcium sulfate material and a non-recycled calcium sulfate material, wherein the ratio of the recycled calcium sulfate material to the non-recycled calcium sulfate material is at least 1:1.
[0022] Preferably, the plasterboard has a density of 960 kg / m 3 or less. More preferably, the plasterboard has a density of 760 kg / m 3 or less. Preferably, the plasterboard has a density of 520 kg / m 3 or more. More preferably, the plasterboard has a density of 680 kg / m 3 or less. Preferably, the plasterboard has a thickness of 12.5 mm or less.
[0023] Preferably, the plasterboard comprises a core containing paper in an amount of 2.2 wt% or less. More preferably, the plasterboard comprises a core containing paper in an amount of 2 wt% or less. Even more preferably, the plasterboard comprises a core containing paper in an amount of 1.7 wt% or less, or 1.6 wt% or less, or 1.5 wt% or less. Even more preferably, the plasterboard comprises a core containing paper in an amount of 1.2 wt% or less. Even more preferably, the plasterboard comprises a core containing paper in an amount of 1 wt% or less, or 0.84 wt% or less. Even more preferably, the plasterboard comprises a core containing paper in an amount of 0.7 wt% or less, or 0.5 wt% or less, or 0.4 wt% or less. Most preferably, the plasterboard comprises a core containing paper in an amount of 0.2 wt% or less.
[0024] Preferably, the plasterboard contains a fluidizing agent in an amount of less than 1 wt% of the dry weight of the calcium sulfate material. Preferably, the plasterboard contains a fluidizing agent in an amount of less than 0.1 wt% of the dry weight of the calcium sulfate material.
[0025] According to a third aspect of the present invention, there is provided the use of a plasterboard as described herein and / or produced by a method as described herein.
Mode for Carrying Out the Invention
[0026] Next, embodiments of the present invention will be described as mere examples.
[0027] It is known that changing the particle size of the calcium sulfate material used in the production of plasterboard can affect the production process. Experiments were conducted to study the effect on the particle size of incorporating recycled calcium sulfate material.
[0028] Here, as a first step, a mixture of non-recycled calcium sulfate material and recycled calcium sulfate material was pulverized and fired. The particle size produced by this process was controlled by changing the selector position on the pulverizer. The selector position controls the outlet of the mixture from the pulverizer, and a higher selector position corresponds to a longer residence time and a smaller particle size. The Blaine value of the pulverized and fired material produced in each test was measured and is shown in detail in Table 1 below.
Table 1
[0029] The preferred Blaine value of the pulverized and fired mixture depends on the overall plasterboard production process, but in this case, a value of less than 8000 cm 2 / g is preferred. This preferred Blaine value can be the value for both pure non-recycled gypsum (calcium sulfate material 6) and a mixture containing a conventional level of recycled material (calcium sulfate material 5). When the amount of recycled material was increased to a 1:1 ratio with the non-recycled material, as in calcium sulfate material 4 and calcium sulfate material 4b, the desired Blaine value could be obtained.
[0030] Exceeding the Blaine value measured for the calcium sulfate mixture can also affect the composition of the mixture itself and its suitability for the manufacture of plasterboard.
[0031] To investigate this, samples of calcium sulfate material 3, calcium sulfate material 4, and calcium sulfate material 4b were used in further experiments. Here, the achievable line speed during manufacture and the weight % of calcium sulfate anhydride after firing were measured and compared with existing methods. Here, the proportion of calcium sulfate anhydride is measured as the weight % of the fired material.
[0032] The results of these experiments are detailed in Table 2.
Table 2
[0033] From Table 2, it can be seen that increasing the amount of recycled calcium sulfate material affects the overall manufacturing process and the composition of the fired material. First, it should be noted that as the amount of recycled material increases, the amount of calcium sulfate anhydride in the mixture after firing increases. The presence of calcium sulfate anhydride is typically undesirable because of the high water requirement during the manufacturing process. This high water requirement is often observed as a decrease in the achievable line speed during the manufacturing process. This effect is also observed in Table 2.
[0034] However, despite the increase in the amount of calcium sulfate anhydride found in the mixture, it should be noted that the amount of calcium sulfate anhydride present after firing of the non-recycled calcium sulfate material and the recycled calcium sulfate material is less than the preferred 20 wt%, more preferably less than 16 wt%, and most preferably less than 10 wt%. Therefore, the line speed of the manufacturing process when using a 1:1 ratio of recycled material to non-recycled material does not drop below 84% of the speed of an equivalent process where the mixture does not contain recycled calcium sulfate material.
[0035] When the calcium sulfate anhydride content of the firing mixture is exceeded, the other components of the mixture introduced by the recycled material can affect the water requirement of the mixture during the plasterboard manufacturing process. One of the components that has the greatest impact on the water requirement is known to be paper. Since paper is often used as the surface layer of plasterboard, it is often present in the recycled calcium sulfate material. Therefore, it is important to keep the paper content in the particle mixture at 2.2 wt% or less.
[0036] To show the effect of the paper content on the production of plasterboard, experiments were conducted as outlined below.
[0037] Here, a 200 g sample of the calcium sulfate material (containing 50% non-recycled calcium sulfate material in the form of calcium sulfate hemihydrate and 50% recycled calcium sulfate material) was prepared. The recycled calcium sulfate material contained 0.4 wt% paper fibers. Therefore, the sample included a baseline value of 0.2 wt% paper fibers. Then, additional paper fibers were added to the sample in various amounts, and water was added to the mixture to form a slurry.
[0038] Next, each slurry sample was mixed in a mixer at a constant speed for 10 seconds to ensure complete mixing of its components. The viscosity of the slurry was measured using a slump test, and each slurry sample was placed in a cylindrical mold with a diameter of 60 mm and a height of 50 mm on a glass substrate.
[0039] Thereafter, the mold was removed by lifting it so that the slurry was not supported. After removing the mold, the spread of the slurry across the substrate was measured 20 seconds later. At the end of that time, three measurements were taken at different points across the spread of the slurry, and the average of those measurements was recorded.
[0040] To measure the influence of paper on the water requirement of a mixture of solid materials, the viscosity of a sample containing 0.2 wt% of paper fibers was measured. To characterize the increase in water requirement, the amount of water added to the paper fiber-containing sample was increased until the spread of the same slurry was observed. In this way, the increase in water requirement could be characterized. The results of these experiments are shown in Table 3. [Table 3]
[0041] Here, the water volume gauge of the slurry is calculated using the following formula. [Equation]
[0042] As can be seen from Table 3, increasing the amount of paper fibers in the sample from 0.2 wt% to 0.7 wt% had no effect on the slurry viscosity. This is proven by the fact that Example 5 showed the same fluidity as Example 4 without using additional water required to obtain the same measured slump value.
[0043] As the paper content increased, additional water was required to maintain the same slurry viscosity as seen in Example 4. In Example 6 containing 1.2 wt% of paper, the moisture content increased to 79%. In Example 7 containing 2.2 wt% of paper, the moisture content increased to 83%.
[0044] Therefore, samples containing 2.2 wt% or less of paper showed water requirements acceptable for the industrial production of plasterboard, but a paper content of 0.7 wt% or less in the solid mixture used to form the slurry did not result in a measurable increase in water requirement.
Claims
1. A method for manufacturing a plasterboard, comprising the steps of mixing at least one recycled calcium sulfate material and at least one non-recycled calcium sulfate material to form a particle mixture, mixing at least the particle mixture and water to form a solidifiable slurry, and drying the solidifiable slurry to form a plasterboard , wherein the ratio of the recycled calcium sulfate material to the non-recycled calcium sulfate material in the particle mixture is at least 1:1, and further comprising the step of firing the particle mixture before mixing the particle mixture with water to form a solidifiable slurry.
2. The method according to claim 1, further comprising the step of pulverizing the particle mixture before mixing the particle mixture with water to form a solidifiable slurry.
3. The method according to claim 2, wherein the average residence time of the particles in the particle mixture in the pulverizer is less than 75 seconds.
4. The Blaine value of the pulverized and fired material is less than 8000 cm ２ / g, more preferably less than 7000 cm ２ / g, according to the method according to any one of claims 1 to 3.
5. After firing, the particle mixture contains less than 20% by weight of calcium sulfate anhydride, preferably less than 16% by weight of calcium sulfate anhydride, and most preferably less than 10% by weight of calcium sulfate anhydride. The method according to any one of claims 1 to 4.
6. The method according to any one of claims 1 to 5, wherein the at least one non-recycled calcium sulfate material comprises calcium sulfate hemihydrate and / or calcium sulfate dihydrate.
7. The method according to any one of claims 1 to 6, wherein the at least one recycled calcium sulfate material comprises calcium sulfate dihydrate.
8. The method according to any one of claims 1 to 7, wherein the at least one recycled calcium sulfate material comprises calcium sulfate hemihydrate.
9. The method according to any one of claims 1 to 8, wherein the particle mixture contains 2.2% by weight or less of paper, preferably 1.2% by weight or less of paper.
10. Manufacturing an equivalent plasterboard at a rate exceeding 80%, preferably exceeding 90%, of the rate of an equivalent process in which the particle mixture does not contain a recycled calcium sulfate material. The method according to any one of claims 1 to 9.
11. A plasterboard containing a recycled calcium sulfate material and a non-recycled calcium sulfate material, wherein the ratio of the recycled calcium sulfate material to the non-recycled calcium sulfate material is at least 1:
1.
12. 2. The plasterboard according to claim 11, comprising a core containing paper in an amount of 2.2% by weight or less, preferably 1.2% by weight or less.
13. 3. The plasterboard according to claim 11 or claim 12, comprising a fluidizing agent in an amount of 1% by weight or less of the dry weight of the calcium sulfate material.
14. 680 kg / m ３ to 760 kg / m ３ The plasterboard according to any one of claims 11 and 12, having a density of