Method and device for producing a gypsum mixture as a spreadable and quick-drying stucco gypsum mixture and stucco gypsum mixture produced by said method

Abstract

The invention relates to a method for producing a total gypsum mixture as a spreadable stucco gypsum mixture from dry gypsum with the addition of water, characterised in that the total dry gypsum is divided into a first and a second partial quantity, in that the quantity of the total added water required at least for the first and the second partial quantity corresponds to the stoichiometric water requirement of the gypsum content of the total gypsum mixture, in that the gypsum mixture is produced in a two-stage mixing process, wherein, in a first mixing step, the first partial quantity of the gypsum is produced as a first partial mixture by adding water as a gypsum foam, and in that, in a second mixing step, the second partial quantity is added as a second partial mixture to the first mixture and thus a spreadable gypsum mixture is produced as a total gypsum mixture and the gypsum foam is destroyed again in the process.

Description

[0001] -10-2025-43878401-Main Post Office-0014 06-10-2025— 43878401~Main Post Office iPcs i“0014 PCT / DE2025 / 000098

[0002] 1

[0003] Method and apparatus for producing a gypsum mixture as a spreadable and fast-drying plaster of Paris mixture and plaster of Paris mixture produced by the method

[0004] 5 The invention relates to a method according to the preamble of claim 1.

[0005] From EP 1 907 334 B1, fast-drying gypsum products are known. A gypsum slurry and a wall panel are disclosed which require less drying time than

[0006] Ten conventional products are needed. One reason for the low cost of wall panels is that they are manufactured using a fast and efficient process. To form the core, a slurry of calcium sulfate hemihydrate and water is used, which is continuously applied to a paper cover sheet running under a mixer. A second paper cover sheet is then applied, and the resulting unit is formed into a panel. The calcium sulfate hemihydrate reacts with a sufficient amount of water to convert the hemihydrate into a matrix of interlocking calcium sulfate dihydrate crystals, causing it to harden and become rigid. The resulting continuous strip is conveyed on a conveyor belt until the calcined gypsum...

[0007] Once the tape has cured in 20 minutes, it is cut into sheets of the desired length and then passed through a drying oven to remove excess moisture. Each of these steps takes only a few minutes. The reduction in the water-gypsum content is achieved here by specifying molecular structures and their sequence in a flow agent used in the process.

[0008] From DE 10 2017 111 018 B4, a spreading system for producing spreading material mats from spreading material, in particular wood fibers or wood chips, in the course of the production of wood-based panels or similar panels, e.g. fiberboard or particleboard, is known, with a spreading belt conveyor onto which the spreading material is fed, forming the

[0009] 30 spreading material mats are spread and equipped with an equalizing device for evenly distributing the material on the spreading belt conveyor, which has at least two (rotating) distribution rollers with distribution tools distributed across the roller width and circumference. -i0-2025-4387840i-Main Post-00i5 06~10-2025~43878401-Main Post Office t-0015 PCT / DE2025 / 000098

[0010] 2

[0011] In the context of panel manufacturing, spreading refers to the even distribution of fine material such as particles, fibers, or small agglomerates across its width and length, with the thickness adjusted for subsequent compaction. Both dry and semi-dry materials can be used.

[0012] 5. The water for the binder can be introduced through the aggregate, e.g. through moist wood particles or wood shives, as is known from DE 2 919 311 B1, through other aggregates and lightweight aggregates, or through the binder particles themselves, or through additives such as fibers.

[0013] 10

[0014] The phase composition of a plaster of Paris binder determines its technological properties, such as its water requirement, i.e., the ratio of water to gypsum during preparation (hereinafter also referred to as the water-plaster ratio), its workability, and the

[0015] 15 Hydration rate. The present invention takes into account the influence of different phase compositions in the binder on hydration and the resulting solid properties.

[0016] The hardening of gypsum building materials is based on the crystallization of calcium sulfate-

[0017] 20 Dihydrate from a solution supersaturated with respect to this phase. The intergrowth and interlocking of the resulting dihydrate crystals is primarily responsible for the formation of a solid structure and is thus the cause of the strength and stability of gypsum products.

[0018] 25 In nature, calcium sulfate occurs as a dihydrate, known as gypsum, or as anhydrous anhydrite II.

[0019] It is known that combinations of different superplasticizers or combinations of specially formulated substances can be used to lower the water-gypsum content of building material mixtures.

[0020] to use 30 pre-mixed flow agents with other additives.

[0021] For example, WO 2019 226 633 A1 discloses core layers of gypsum boards with water-to-gypsum ratios, i.e., with water-to-gypsum ratios, of 0.3 to 0.9 and 0.3 to 0.4. -i0-2025-4387840i-Main-Post-00i6 06- 10-2025-43878 01-Main-Post t-0016 PCT / DE2025 / 000098

[0022] 3

[0023] WO 2019 226 596 A1 also reveals core layers with water-gypsum values ​​of 0.3 to 0.9 and 0.3 to 0.4.

[0024] 5 From US 9 328 025 B2, it is known to produce a first mixture of gypsum with a plasticizer and water, and a second mixture comprising gypsum, plasticizer, foam, and water. In this process, the foam is first mixed with the plasticizer and water and then combined with the second quantity of gypsum. The aim is to control the bubble size distribution of the foam.

[0025] 10

[0026] In addition to the use of additives, particularly flow agents, as described above, the use of additives during the calcination of gypsum plaster is also described. Water-gypsum sprueti values ​​of 0.5 to 0.8 are known from WO 2019 226 596 A1.

[0027] 15

[0028] The use of calcium sulfate α-hemihydrate for the production of building materials, possibly in mixtures with cement, is also known. An example of this is WO 2015 168 078 A1. There, a cement-calcium sulfate hemihydrate mixture is mixed with a wetting agent mixture and water; this enables water-gypsum values.

[0029] 20 from 0.17 to 0.3.

[0030] Water gypsum values ​​as low as 0.18 are described in US 2008 202 415 A1 and US 2008 303 191 A1 when using cellulose ethers.

[0031] 25. Reductions in water gypsum levels could also be achieved through constructive measures on the systems. However, these do not allow operation in the range of stoichiometric water demand, as described in the case of the use of additives.

[0032] 30 DE 28 10 993 A1 discloses a process for the continuous treatment of calcined gypsum to produce gypsum hemihydrate (calcium sulfate hemihydrate) that has a low water requirement, does not solidify quickly, and is suitable for the automatic production of gypsum boards. In this process, at least a portion of the feed stream of calcined gypsum for a board slurry mixer is treated as such. -10-2025-43878401 -Hau ptpost-0017 06- 10-2025-43878401 -HauP t Po s 1-00 i 7 PCT / DE2025 / 000098

[0033] 4. A high-performance mixer is diverted. Water is continuously added to the calcined gypsum. The water and calcined gypsum are mixed homogeneously to a degree sufficient to incorporate approximately 1 to 8 wt.% free water into the mixture, where the wt.% values ​​refer to the total volume.

[0034] 5. The mixture is based on calcined gypsum. It is then allowed to cure for approximately 1 minute. This mixture is then fed into a gypsum slurry mixer of a gypsum board production line.

[0035] DE 28 10 993 A1 thus describes a stucco gypsum stabilization method (sometimes

[0036] 10 (also called "artificial aging"). Stucco gypsum stabilization essentially means that the alkyldimethoxide III contained in the stucco gypsum is hydrated to gypsum hemihydrate over a certain period of time. In DE 28 10 993 A1, the stabilized stucco gypsum is produced by extracting a subset of stucco gypsum from a given quantity of stucco gypsum and subjecting it to an artificial aging process.

[0037] 15. The gypsum is allowed to react, and after a "maturation period", a slurry is produced from the mixture prepared according to the description by adding the main amount of water, which is then processed into a board in a conventional plasterboard plant.

[0038] 20 The information on the percentage of free moisture in DE 28 10 993 A1 refers to the total mass of the plaster of Paris. DE 28 10 993 A1 discloses a so-called wet process for the production of wet plasterboards, which subsequently have to be dried in an oven.

[0039] 25 In DE 28 10993 A1 it is explained that approximately 85 to 100 parts of water are required. After the reaction, approximately 67% to 82% of the water must be dried off.

[0040] Also on page 9 of DE 28 10 993 A1, a general goal is a water saving of 20 to 50% on the consistency, i.e., on the freshly mixed

[0041] 30 parts of plaster of Paris are specified. This would reduce the stated water content for producing the slurry to 42.5 to 80 parts by mass. On page 12, the actual target for water savings is listed: The water requirement of the calcined gypsum, i.e., the plaster of Paris, is to be reduced by 20% to 30%. In this case, the 85 to 100 parts would be reduced to 59.5 to 80 parts. At the same time, -10-2025-43878401 -Hau ptpost-0018 06- 10-2025-43878401-HaufH Pos i-0018 PCT / DE2025 / 000098

[0042] 5 pointed out that this process describes a sub-process of plate manufacturing, which indicates that it is a wet process.

[0043] The purpose of the invention is to create a plaster of Paris with a low

[0044] 5. Adding water to process.

[0045] According to the invention, this problem is solved as specified in claim 1.

[0046] The invention relates to the production of a free-flowing, so-called

[0047] 10 semi-dry plaster mixtures, revealed.

[0048] The plaster of Paris mixture is based on plaster of Paris. Plaster of Paris is understood to be gypsum, which consists mostly of calcium sulfate hemihydrate and is fired at a low temperature, for example up to 180 °C. Besides the

[0049] 15. Calcium sulfate hemihydrate contains, to a lesser extent, stucco gypsum, usually one or two forms of anhydrous calcium sulfate, which are referred to as anhydrite III and anhydrite II and differ not chemically, but crystallographically. In addition, small amounts of calcium sulfate dihydrate, i.e., gypsum, may be present. This can be uncalcined raw material or gypsum that has been

[0050] 20. was formed erroneously from the three aforementioned components by reverse reaction due to improper handling, e.g., by reaction with atmospheric humidity.

[0051] The plaster mixture according to the invention dries quickly because, unlike usual, it is not

[0052] 25. The advantage is not only that the drying time for boards is reduced in a drying plant, but also because – unlike the method known from the aforementioned document DE 28 10 993 A1 – no drying by a drying device is required at all. After the binders have reacted, the boards produced according to the invention have a free moisture content of up to 10%.

[0053] 30. This limit is maintained because the panels are manufactured with a near-stoichiometric moisture content. The slight excess moisture therefore dries in the air until the equilibrium moisture content is reached. The percentage of free moisture is based on hydrated material to estimate whether drying is necessary. -10-2025-43878401 -Hau ptpost-0019 06- 10-2025-43878401-HauPiPos t-0018 PCT / DE2025 / 000098

[0054] 6

[0055] To facilitate understanding of the invention, some common technical terms from the relevant field are used below and explained in a manner specific to the invention:

[0056] 5 The term “water-gypsum value (EM)” refers to the ratio of water to gypsum obtained from a standard method for a plaster of Paris, for example, by determining the amount of aggregate (EM) or by determining the flow rate (FM). Both methods are described in DIN EN 13279-2 (Oct. 2004). Water-gypsum values ​​determined according to the

[0057] The values ​​determined using the first method are referred to as the water-gypsum value (EM), or abbreviated W / G-EM; those determined using the second method are referred to as W / G-FM. Typical values ​​for the stucco plasters considered here range from approximately 0.65 to 0.8.

[0058] 15. Chemical or stoichiometric water demand refers to the amount of water required for calcined gypsum to be completely converted to calcium sulfate dihydrate. Pure gypsum hemihydrate, which constitutes the main part of plaster of Paris, requires the addition of 0.186 parts water. Pure anhydrite III and pure anhydrite II, which are also present in plaster of Paris, require the addition of 0.186 parts water.

[0059] The 20 possible occurrences each require an addition of 0.2647 parts. This value will be referred to below as the stoichiometric water requirement.

[0060] Water-gypsum value (T): A water-gypsum mixture can also have a different water-gypsum value than that specified by a test method (e.g., DIN EN 13279-2 (Oct. 2004)).

[0061] 25 specific water-gypsum values, for example W / G-EM, are produced. The water-gypsum values ​​of such mixtures are subsequently referred to as water-gypsum value (T) or W / GT (T = Technical Method). This also applies if the entire mixture contains aggregates.

[0062] 30 Water-solids value (T): For a gypsum mixture with non-reactive components such as aggregates, fillers, or lightweight aggregates, the added water can be related not only to the gypsum but to all solids: water-solids value (T) or W / FT. (T for Technical Process). The distinction between one of the aforementioned water-gypsum values ​​(EM; FM; T) and a water-solids value (T) is defined by -10-2025-43878401 -Hau ptpost-0020 06- 10-2025-43878401-HauPtPos t-0020 PCT / DE2025 / 000098

[0063] 7

[0064] This is important because both values ​​must be considered for application. For example, while the water-based gypsum value (EM, FM, and T) and the water-solids value (T) are identical in a mixture consisting solely of plaster of Paris, water, and additives, the water-solids value (T) changes, for example, with the addition of an aggregate.

[0065] 5. The water-gypsum value (EM, FM or T) remains the same. It must then be checked whether the material properties of the new mixture have changed so significantly that recipe adjustments are necessary.

[0066] The goal is therefore to formulate a plaster mixture that complies with the listed specifications.

[0067] The material is processable using the 10-step method and, according to the terminology mentioned above, has a water-solids content (T) for the total mixture that is at most approximately equal to the stoichiometric water demand of the gypsum it contains. The gypsum it contains will consume all the water, and there will be no or only negligible amounts of water left in the hardened building material: drying is unnecessary.

[0068] 15

[0069] The method according to the invention is characterized in that the entire dry gypsum is divided into a first and a second subset, that the total amount of added water is determined as the water requirement for the entire gypsum mixture, and that the gypsum mixture is produced in a two-stage mixing process.

[0070] 20 wherein in a first mixing step the first subset of the gypsum is produced as a first partial mixture by adding water as gypsum foam and wherein in a second mixing step the second subset is produced as a second partial mixture as a spreadable gypsum mixture, wherein the foam is destroyed in the second mixing step.

[0071] 25

[0072] This assumes that the plaster of Paris added in the second mixing step draws so much water from the foam mixture of the first mixing step that the foam is destroyed. However, immediately before the addition of the second partial mixture, the plaster of Paris particles from the first partial mixture have been sufficiently broken down by the foam.

[0073] 30 spaced apart, so that the plaster particles of the second mixture are quickly and homogeneously mixed in.

[0074] Advantageous further developments result from the subclaims and the description. -10-2025-43878401 -Hau ptpost-0021 06-10-2025-43878401-HauP iPos t-0021 PCT / DE2025 / 000098

[0075] 8

[0076] It is advantageous according to the invention that a semi-dry gypsum mixture is produced in the second mixing step.

[0077] 5 Advantageously, the semi-dry gypsum mixture is formed into a middle layer of a multi-layer board, or the matrix of a gypsum-containing board is formed from the semi-dry gypsum mixture.

[0078] Preferably, such a plate is equipped with at least one sheet-like element.

[0079] 10 coatings are laminated.

[0080] Preferably, at least one coating is designed as a cardboard or nonwoven coating.

[0081] 15 It proves advantageous if the quantity of water added to the gypsum mixture is determined as corresponding to the stoichiometric water requirement of the entire stucco gypsum.

[0082] It is also advantageous if additional water is added in the second mixing step.

[0083] 20 is added. The mixing process takes place in batches or continuously.

[0084] Preferably, the total amount of water added for the entire gypsum mixture is to be determined by calculating the stoichiometric water requirement of the gypsum component of the total mixture and this

[0085] 25. Add the entire amount of water in the first mixing step to the part of the plaster of Paris for which the determination of the water-gypsum value via the amount of sprinkled water or via the flow measure is the basis of the calculation.

[0086] Advantageously, a light aggregate and a

[0087] 30 foaming agents added.

[0088] According to a particular embodiment of the invention, perlite is added to the first partial mixture. -10-2025-43878401-Main Post-0022 06" 10-2025-43878401-Main Post t Pos “ÖO22 PCT / DE2025 / 000098

[0089] 9

[0090] It is also advantageous to use a flow agent.

[0091] Fibers are preferably used, and these fibers can be polypropylene fibers, glass fibers, or organic fibers.

[0092] 5

[0093] Likewise, a pre-fabricated combination of a flow agent and fibers can be used to advantage.

[0094] The invention also relates to a device for manufacturing gypsum boards for carrying out one of the methods described above. The device is characterized in that it is equipped with a spreading device.

[0095] The invention also relates to a gypsum board with a gypsum board core or at least one layer of gypsum, wherein at least the gypsum board core or

[0096] 15 that at least one layer is produced according to one of the methods listed above.

[0097] Preferably, the gypsum board is produced on a spreading and forming system for cement-bonded wood fiberboards or cement building boards.

[0098] 20

[0099] Furthermore, the invention also relates to a spreadable plaster of Paris mixture produced according to one of the methods listed above.

[0100] According to the invention, mixing methods and formulations of a plaster of Paris mixture for use in gypsum plasterboard are disclosed. The gypsum plasterboard can be used as a matrix, for example in laminations with cardboard, or as the middle layer of multi-layered gypsum plasterboard. The method described in the invention enables the production, dosing, spreading, and shaping of such a plaster of Paris mixture. This is achieved through a two-stage process.

[0101] 30 Mixing process and the processing of the mixture on spreading devices. In the mixing process, a first stucco plaster mixture is used, which contains all the mixing water, a porous lightweight aggregate and a foaming agent, as well as the portion of plaster for which this water is sufficient for processing. The resulting -10-2025-43878401 -Hau ptpost-0023 06- 10-2025-43878401-HauP t Pos -t-0023 PCT / DE2025 / 000098

[0102] The 10 units of produced gypsum foam allow the remaining gypsum to be mixed into a second, dry mixture.

[0103] The water in the first plaster mixture corresponds approximately to the chemical

[0104] 5. The water requirement of the sum of the gypsum from the first and second partial mixtures, and thus of the entire gypsum mixture, is such that no subsequent drying step is necessary. By sacrificing the foam of partial mixture 1, the additional plaster of Paris from partial mixture 2 can be mixed in dry, resulting in a pourable plaster of Paris mixture, such as that found, for example, on

[0105] 10. It can be processed using commercially available systems. Systems based on this spreading technology are technically established and widely used, for example for cement-bonded wood panels.

[0106] A plaster mixture and a mixing process for the production of a

[0107] 15. A gypsum mixture with approximately stoichiometric water content is disclosed. Such gypsum mixtures can be processed into gypsum boards on plants for the production of cement-bonded wood panels or cement building boards, such as those offered by Grenzebach BSH GmbH, which no longer need to be dried or only with extremely reduced effort. Such mixtures are referred to as

[0108] 20 semi-dry mixtures, the process is referred to as semi-dry process.

[0109] Part of the energy consumption in the production of gypsum boards results from the drying of the portion of the added water that ensures the workability of the mixture, but is not consumed during the hydration of the semi-hydrated gypsum.

[0110] turned 25.

[0111] The method disclosed according to the invention contributes to reducing this energy expenditure. It lowers the water demand and the water-to-gypsum ratio (T) of the overall mixture of the middle layer of a multilayer panel.

[0112] 30 or a matrix of a gypsum board with lamination to approximately 0.2 and thus to the stoichiometric water demand of the stucco gypsum contained in this mixture, in contrast to the conventional procedure with water-gypsum values ​​(T), which are mostly around 0.65 to 0.8. In the conventional procedure, the water-gypsum values ​​(T) and (EM) therefore coincide, whereas in -10-2025-43878401 -Hau ptpost-0024 06- 10.-2025-43878401-Ha P tPos t-0024 PCT / DE2025 / 000098

[0113] 11. According to the inventive method, the water-gypsum value (T) corresponds to the stoichiometric water demand of the contained stucco gypsum. In a production plant, under technical conditions (for example, in plant engineering or with a special formulation), water-gypsum values ​​of 0.18 to 0.2 are obtained from the stoichiometric water demand.

[0114] The following table presents a greatly simplified version of this, whereby in both cases the water-gypsum value of the plaster of Paris used, determined by the amount of aggregate, is between 0.65 and 0.8:

[0115] 10

[0116] Another advantage of the invention is that gypsum mixtures can also be produced in locations with low water levels, minimizing or completely eliminating the use of water, which would otherwise have to be dried according to the prior art methods.

[0117] Descriptions of methods for lowering the water gypsum value (T) by using chemical additives such as the combination of different superplasticizers in partial mixtures and superplasticizers of special formulation or other additives are known, for example, from the above-mentioned WO 2019 226 633 A1 , WO 2019 226 596 A1 and US 9 328 025 B2.

[0118] The procedure described below allows the production of a finely divided, i.e., almost dry, gypsum mixture suitable for spreading, which can then be processed into a board or the main layer of a multi-layer board on a system 25 for the production of building material boards, in particular on a spreading system such as is used for cement-bonded wood boards and in cement building board plants.

[0119] Such spreading devices are described, for example, in "MDF - Medium Density 30 Fiberboard" by H.-J. Deppe and K. Ernst, Leinfelden-Echterdingen, 1996, pages 86-10-2025-43878401-Hauptpost-0025 06-10"2025-43878401-HauPt os t"0025 PCT / DE2025 / 000098

[0120] 12 to 92. After spreading, the material was shaped by means of compression using a roller.

[0121] The mixing process is described below using an exemplary embodiment:

[0122] Method 5 comprises the preparation of two partial mixtures, the distribution of the gypsum plaster component of the total mixture according to the procedure described below, and the sequential processing of the two partial mixtures, also according to the procedure described below. The mixing can take place in a single mixing vessel or, in a continuous mixing process, in successive mixing zones.

[0123] A typical mixture consists of the two sub-mixtures and the following components:

[0124] 15. Partial mixture 1 consists of the following materials:

[0125] Plasterboard

[0126] Portland cement (for pH adjustment),

[0127] Foaming agent

[0128] 20 high-performance flow agents (optional; recommended),

[0129] Lightweight aggregate: Conventional perlite, i.e., open-pored expanded perlite.

[0130] If necessary, other additives commonly used in gypsum board manufacturing, such as retarders, accelerators, hydrophobizers, rheology modifiers, wetting agents, strength enhancers, etc., can be added.

[0131] In addition to perlite, for example expanded perlite, fibers, standard aggregates, or other lightweight aggregates can also be used. If these lightweight aggregates are porous, they can completely or partially replace the expanded perlite.

[0132] 30

[0133] In the simplest case, the second submixture consists only of the component: plaster of Paris.

[0134] This may again contain additives, fibers, and fillers. -10-2025-43878401 -Hau ptpost-0026 06- 10-2025-43878401-HauP iPos t-002€ PCT / DE2025 / 000098

[0135] 13

[0136] The procedure is as follows: The mixing process is carried out with a mixer that is known per se, for example with a mixer from HOBART GmbH, 77656 Offenburg (DE), or a mixer from Maschinenfabrik Gustav Eirich GmbH & Co.

[0137] 5 KG, 74736 Hardheim (DE), for example an Eirich mixer of the R series, for example a dynamic mixer R02, with 2 different speeds each.

[0138] Preferably, the mixers are operated at varying speeds:

[0139] 10 Hobart mixers slow / fast (rpm): 140 / 285 Eirich mixers R02 slow / fast (rpm): 608 / 859

[0140] Mixing process for partial mixture 1 :

[0141] The added water, the previously added foaming agent, possibly also flow agent and / or

[0142] After 15 retarders have been added, a dry mixture of the solids plaster of Paris / cement / perlite is added to a mixer of the type mentioned above in such a way that a foam plaster is created.

[0143] The mixing speeds are chosen as follows: 15 s slow, 15 s

[0144] 20 quickly.

[0145] The foam forms during the second period, i.e., during the second 15 seconds.

[0146] Mixing process for partial mixture 2: Partial mixture 2 can, if it consists of

[0147] If the component 2 consists of several components, it must be premixed in the same or a largely identical manner as the dry component 1. If the component 2 consists of only one component or of a component mixture that was previously provided ready-made, a dry premix is ​​unnecessary.

[0148] 30

[0149] The pre-mixed partial mixture 2, prepared from the mixing process of partial mixture 1, is now carefully folded or mixed into the foam plaster during the mixing process for the second partial mixture. Here, the following information is used: -10-2025-43878401 -Hau ptpost-0027 06- 10-2025-43878401 -HauP Po s t- 0027 PCT / DE2025 / 000098

[0150] 14

[0151] Mixing speeds were preferably chosen as follows: 15 s slow, 15 s fast.

[0152] The second, faster time period of this mixing process for the second partial mixture

[0153] Step 5 leads to the dissolution of agglomerates, insofar as they were formed in the first stage of this mixing process. The foam is destroyed.

[0154] The added water of partial mixture 1, which corresponds to the stoichiometric water requirement of the entire plaster of Paris, is sufficient at the end of the

[0155] 10. Preparation of partial mixture 1 is therefore carried out to wet both the plaster of Paris mixture and the formed foam bubbles. This changes with the addition of partial mixture 2, which is now also wetted and, in addition, removes the liquid shell from the foam bubbles: The foam disappears.

[0156] 15. The mixing process for the second partial mix and the obtaining of a homogeneous, so-called semi-dry mix succeeds because partial mix 1 provides a volume that allows the incorporation of further gypsum (partial mix 2): The gypsum particles are sufficiently far apart due to the foam at the beginning of the second mixing process. This accepts

[0157] 20 assumed that the foam and part of the perlite (expanded perlite) will be destroyed during the mixing process for the second partial mixture and that the mixtures will be prepared according to the following instructions regarding the distribution of the plaster of Paris onto the two partial mixtures.

[0158] 25 Of particular importance in the production of the spreadable plaster of Paris mixture is, in addition to a) the two-stage procedure in the mixing process, b) the at least partial sacrifice of the perlite, c) the weighting of the two mixtures with regard to the distribution of the plaster of Paris between the two mixtures, which is carried out as follows:

[0159] 30 a) The water demand of the plaster of Paris is calculated from the chemical analysis. However, it is often sufficient to simply use a value of 16–20%, based on the binder, i.e., a water-to-gypsum ratio (W / G ratio (T)) as follows: W / G ratio = 0.16 to 0.2. The stoichiometric water demand of a pure β- -10-2025-43878401 -Hau ptpost-0028 06-10-2025“43878401-HauPiPos t-0Q28 PCT / DE2025 / 000098

[0160] 15

[0161] The stoichiometric value of the β-hemihydrate is approximately 0.186. This value decreases slightly if the gypsum contains impurities. It is also possible to work with a slightly substoichiometric ratio, meaning with a slight water deficit, in which case some of the β-hemihydrate remains unreacted. If the plaster of Paris contains significant amounts of anhydrite III, the stoichiometric water-gypsum value increases slightly above 0.186 in the case of 100% purity.

[0162] Small amounts of residual water are not a problem, as the water content in the semi-dry technique used here may be up to 10% free moisture at the end of the reaction time. This dries down to 4% in ambient air. This results in the specified fluctuation range of the water-gypsum values ​​from 0.16 to 0.2. When working with gypsum topcoats, the middle layer would even be deliberately mixed below stoichiometrically; any additional water would then be "absorbed" from the topcoats. b) Using a common method (determining the amount of aggregate; determining the water demand via flow coefficient), the water-gypsum value (EM or FM) of the pure stucco gypsum is determined. This is significantly higher than the value under a).

[0163] 20. Calculated stoichiometric claim, for example at 0.65 to 0.8. c) All the water is added to partial mixture 1 in the first mixing process. From b) the proportion of plaster of Paris that is added to mixture 1 so that the plaster of Paris is workable is calculated.

[0164] The remaining 25% of the plaster of Paris is added to the second batch of mixture. At the end, the water-to-gas (W / G) value (T) of the entire finished mixture after the second mixing process is again 0.2, and drying is not required.

[0165] In the first mixture, the water-gypsum value, depending on the specific determination, is usually around 0.65 to 0.8 and includes all the water from both mixing processes. Therefore, the water-gypsum value (T) and the water-gypsum value (EM; FM) are identical in the first mixture.

[0166] The table above can now be greatly simplified and extended to: -10-2025-43878401-Main-Post-0029 08~ 10~2025 _ 43878401— Main os ■t“00 9 PCT / DE2025 / 000098

[0167] 16

[0168] The resulting mixtures are spread and pressed for panel production; they can form the middle layer of a multi-layer panel or the core of a panel.

[0169] 5 Monoplate with or without lamination, a wall element (wall panel (also known as Gypsum Blocks and Big Wall elements) or a floor element (raised floor panel).

[0170] The addition of other additives such as fibers, etc., is carried out in a manner known per se.

[0171] 10

[0172] In cases where it is not absolutely necessary to work entirely without a dryer, the water-gypsum values ​​(T) of the overall mixtures can be increased accordingly when using additives with high specific surface areas (dusts) or strong absorbency (fibers), for example, if these additives significantly and negatively affect the spreading and shaping properties. The increase then corresponds to the requirement for the additional wetting of these additives, e.g., from 0.18 to 0.28, but not to the water requirement of the plaster of Paris, which is, for example, 0.70. The advantage of water savings through the basic system would be retained, and only the additional water would need to be dried. The energy required for drying would decrease.

[0173] 20 still considerable. -i0-2025-4387840i-Main Post-0030 06- 10~2025~43878401' _ HauiP iPos t~0030 PCT / DE2025 / 000098

[0174] 17

[0175] The stiffening time can be adjusted by adding retarders or accelerators to partial mixture 1. A retarder or accelerator can also be added to partial mixture 2. If partial mixture 2 contains

[0176] 5 For example, if calcium sulfate dihydrate is used as an accelerator, it only becomes active during the forming process into plates or the like, so that even plants with a short length can be realized for the production of plates.

[0177] The well-known spreading and forming devices of Grenzebach BSH GmbH,

[0178] For example, systems 10, used for the production of wood fiberboards or cement boards, allow for the adjustment of different board densities with a single mixture over a wide range. Such systems are also available from other suppliers for the production of cement-bonded wood-based panels using a spreading process. The density is adjusted via the total perlite content.

[0179] 15 their bulk densities and grain size distribution or by varying the ratio of different perlite types.

[0180] Alternative lightweight aggregates can only partially replace uncoated expanded perlite. This is especially true when using combinations of uncoated and expanded perlite.

[0181] 20 expanded perlite and other lightweight aggregates together with the foaming agent ensure that foam formation is guaranteed.

[0182] Generally, the entire perlite content is added to submixture 1.

[0183] 25 One embodiment of this is a board with a top layer coated with flowable gypsum slurries, wherein the board is reinforced with a glass fiber mesh or a glass fiber fabric.

[0184] The composition of a surface layer mixture is given below.

[0185] The top layer is formulated so that the free moisture content in the entire panel is less than 10%. The following values ​​are given in percent:

[0186] Plaster of Paris 73.31

[0187] Portland cement 2.27 -10-2025-43878401 -Hau ptpost-0031 06- 10-2025-43878401-HauP tPos 4-0031 PCT / DE2025 / 000098

[0188] 18

[0189] High-performance flow agent 0.65

[0190] Retarder 0.02

[0191] Added water 23.75

[0192] 5 The composition of the free-flowing middle layer mixture is as follows:

[0193] Taking into account the fluctuation ranges, the following results:

[0194] Table 10: -10-2025-43878401 -Hau ptpost-0032 06- 10- 2025-43878401-HauP Po s t-0032 PCT / DE2025 / 000098

[0195] 19

[0196] The commercially available fiberglass grids / fabrics are placed between the middle layer and the top layers; typical basis weights are approximately 125 g / m². 2 .

[0197] 5 With a mass ratio of the middle layer to the two top layers, in the example given: 1 : 0.3, compliance with the limit value of moisture is guaranteed.

[0198] When the gypsum board is dried at 40 °C, the drying loss is less than 10%. This is the requirement for the method described here. The drying loss according to the standard technique is correspondingly higher, based on the water-gypsum value (EM; FM) of the gypsum, which in this case is approximately comparable to the water-gypsum value (T).

[0199] The bulk density is adjusted, as explained above, via the perlite content of the matrix or, in this case, the middle layer.

[0200] 15

[0201] Such a board does not need to be dried, as its free moisture content is below 10%. The formulations can be expanded to include components that significantly increase the water-gypsum value (T) of the core layer and, consequently, the water requirement of the overall mixture. Only these additional water components of the added water then need to be dried. - -10-2025-43878401-Main-Post-0033 0033 PCT / DE2025 / 000098

[0202] 20

[0203] The reinforcement of the board does not have to be done with a fiberglass mesh, but can also be done with the means introduced for gypsum boards such as fibers, nonwoven mats, cardboard or similar means.

[0204] 5 The core of the invention is formed, according to the following exemplary embodiment, at least by the interaction of the following three features: a) Division of a plaster of Paris powder into two partial mixtures for two mixing steps (partial mixtures 1 and 2), wherein partial mixture 1 is the

[0205] 10 contains all the water and enough gypsum to remain workable with the water. (The remainder of the gypsum forms part 2 or the binder fraction of part 2.) b) Spacing of the particles of part 1 by the foam, so that

[0206] 15. The particles of partial mixture 2 can be mixed in, ensuring that these particles of partial mixture 2 are also uniformly wetted, and simultaneously sacrificing the foam produced in the first mixing step. c) Use of a spreading system to apply the semi-dry mixture thus obtained.

[0207] 20 mixes on one tape.

[0208] According to another embodiment, the following procedure is followed:

[0209] 25. The total amount of water to be added to the entire gypsum mixture is determined by calculating the stoichiometric water requirement of the gypsum component of the total mixture. This total amount of water is added in the first mixing step to the portion of the plaster of Paris for which the determination of the water-gypsum ratio via the amount of aggregate or via the flow rate is the basis.

[0210] 30 calculation is.

[0211] The water content of gypsum plaster was determined to be 0.75 according to DIN EN 13279-2 (Oct. 2004). The stoichiometric water content of the hemihydrate of calcium sulfate is 0.186. (Foreign minerals, anhydrite III and anhydrite II content of the -10-2025-43878401-Hauptpost-0034 06“ 10~2G25-43878401-HauP 4 Pos t~0034 PCT / DE2025 / 000098

[0212] 21

[0213] Calcium sulfate, residual dihydrate components and any other phases of calcium sulfate that are not hemihydrate are not considered separately and are treated like the β-hemihydrate component of the plaster of Paris.

[0214] 5 MSG is supposed to be the mass of the entire plaster of Paris in percent, i.e. 100%.

[0215] ASG is intended to be the percentage of gypsum used to produce the partial mixture.

[0216] 1 is to be used.

[0217] 10 BSG is supposed to be the percentage of gypsum used to produce the partial mixture.

[0218] 2 is to be used, so that:

[0219] MSG = ASG + BSG = 100%

[0220] 15. Therefore, assuming the stucco gypsum MSG to be distributed between the two sub-mixtures is 100%, the proportion ASG for the stucco gypsum assumed here is calculated according to

[0221] (0.186 / 0.75) x MSG = ASG

[0222] 20

[0223] BSG = MSG'- ASG is then the remainder at 100%.

[0224] In practice, 0.2 can be used instead of 0.186.

[0225] 25. Numerical example: 650 g of plaster of Paris are to be used.

[0226] The determination of the amount of aggregate according to DIN EN 13279-2 (Oct. 2004) yielded a water-to-gypsum ratio (W / G ratio) of 0.70. Therefore, the following proportion of stucco gypsum is to be used to prepare partial mix 1:

[0227] 30

[0228] (0.186 / 0.7) x 100 = 26.57% or 172.7 g.

[0229] For partial mixture 2, 100% - 26.57% = 73.43% or 477.3 g remain. -i0-2025-4387840i-Main Post-0035 06~ 10-2025~ 3878401~Haufl tpos ~0035 PCT / DE2025 / 000098

[0230] 22

[0231] In a plant for the production of boards using a mixer 1 (Fig. 1 ), boards are produced with the following layer sequence: top layer - mesh fabric - middle layer - mesh fabric - top layer.

[0232] 5 The invention is explained in more detail below using exemplary embodiments and the accompanying drawings. These show:

[0233] Fig. 1: A first plant for the production of panels with layers of stucco gypsum,

[0234] Fig. 1a shows a layer sequence produced with the system according to Fig. 1,

[0235] Fig. 2 shows another plant for the production of panels with layers of stucco plaster and

[0236] 15 Fig. 2a shows a layer sequence produced with the system according to Fig. 2.

[0237] From a mixer 1 for producing a self-flowing surface layer sludge, the surface layer sludge flows from a storage container 2 downstream of the mixer 1 onto the top of a forming and conveying belt 22, which is supported by a

[0238] The drive roller 13 is driven. On the conveyor belt 22, the top layer sludge forms a top layer 23. Downstream of the storage container 2, in the direction of travel of the conveyor belt 22, is a roller 3 for applying a glass mesh or plastic fabric 24. The glass mesh or plastic fabric 24 is applied to the forming and conveying belt 22 above the top layer 23 by means of the roller 3 for lamination. Then, a mixture for forming a middle layer 25 is applied from a stock box 4 onto a discharge belt 5. From this, the mixture is applied via a brush 8 to discharge or to scrape off the middle layer material onto the glass mesh or plastic fabric 24 and onto the top layer 23, which travels on the conveyor belt 22 in the direction of arrow A.

[0239] 30 is moved. The stockbox 4 is filled with material via a middle layer mixer 7 and this via a storage container 6.

[0240] A compaction roller 9 compacts the layer sequence applied to the conveyor belt 20. A further roller, namely a roller 10, then applies a -i0-2025-4387840i-Hauptpost-0036 06~lÖ~2025~43878401~HauP“tPos t-0036 PCT / DE2025 / 000098

[0241] 23 Another layer of a glass mesh or plastic fabric 26 is applied to the layer sequence already moving on the conveyor belt 22. Then, a self-flowing slurry intended for the formation of the top layer 27 is drawn from a mixer 12 via a discharge conveyor for the top layer slurry.

[0242] 5. A nozzle suitable for the housing 11 discharges the top layer sludge above the glass mesh or plastic fabric 26 onto the layer sequence. The glass mesh or plastic fabrics 24, 26 are each embedded in the top layer 23 or the top layer 27.

[0243] In another embodiment of a system for producing sheets (Fig. 2) with the layer sequence: lamination - middle layer - lamination, a conveyor belt 91 driven by a roller 90 is provided. For lamination, a first strip 15 of paper or cardboard material is applied from a roll 14 onto the conveyor belt 91; alternatively, cardboard or a nonwoven fabric is used.

[0244] 15. Material for the formation of a middle layer 16, to be applied to the first strip 15, is applied from a mixer 50 via a storage container 40 and a stockbox 21, as well as a discharge conveyor 30 and a brush 60 for dropping middle layer material onto the lamination above the first strip 15 onto the conveyor belt 91. A compaction roller 70 compacts the middle layer 16. A top lamination 17 is applied to the middle layer 16 via a roller 80, so that a layered structure of a sheet material is created, from which sheets are subsequently produced after drying by cutting or separating processes.

[0245] 25 The discharge of the material over the brushes 8 or 60 is referred to as spreading. The spreading devices are formed by the combination of the stockboxes 4, 21 with the discharge conveyor 5, 30 and brushes 8, 60.

Claims

-10-2025-43878401 -Hau ptpost-0038 06- 10-2025-43878401-HauP * Pos *-0038 PCT / DE2025 / 000098 1 Patent claims 1. Method for producing a complete gypsum mixture as a spreadable stucco gypsum mixture from dry gypsum with the addition of water, thereby 5 characterized in that the entire dry gypsum is divided into a first and a second subset, that the quantity of total added water required at least for the first and the second subset corresponds to the stoichiometric water requirement of the gypsum component of the entire gypsum mixture, that the gypsum mixture is processed in a two-stage process 10. Mixing process is carried out, wherein in a first mixing step the first partial quantity of the gypsum is produced as a gypsum foam by adding water, and in a second mixing step the second partial quantity is added to the first mixture as a second partial mixture, thus creating a spreadable gypsum mixture as a whole.

15. A plaster mixture is produced, and in the process the plaster foam is destroyed again.

2. Method according to claim 1, characterized in that a semi-dry gypsum mixture is produced in the second mixing step. 20 3. Method according to claim 2, characterized in that the semi-dry gypsum mixture is formed into a middle layer of a multi-layer board or that the matrix of a gypsum-containing board is formed from the semi-dry gypsum mixture. 25 4. Method according to claim 3, characterized in that the plate is laminated with at least one sheet-like coating.

5. Method according to claim 4, characterized in that the at least one coating is a cardboard or nonwoven coating. 30 are being trained.

6. Method according to any one of claims 1 to 5, characterized in that the amount of water added to the gypsum mixture is determined from the stoichiometric -10-2025-43878401-Main Post Office-003SD6~ 10-2025-43878401~Main Post Office t-0039 PCT / DE2025 / 000098 2 The amount of water required for the entire plasterwork is determined.

7. Method according to any one of claims 1 to 6, characterized in that 5. In the second mixing step, more water is added.

8. Method according to one of claims 1 to 7, characterized in that the total amount of water added for the entire gypsum mixture is determined by calculating the stoichiometric water requirement of the gypsum component of the entire gypsum mixture and that in the first mixing step the portion of the plaster of Paris for which the determination via the amount of aggregate or via the flow rate is the basis of the calculation is added.

9. Method according to any one of claims 1 to 8, characterized in that 15. A light aggregate and a foaming agent are added to the first partial mixture.

10. Method according to any one of claims 1 to 9, characterized in that expanded, uncoated perlite is added to the first partial mixture. 20 11. Method according to one of claims 1 to 10, characterized in that a flow agent is used.

12. Method according to one of claims 1 to 11, characterized in that 25 polypropylene fibers or glass fibers or organic fibers are used.

13. Method according to any one of claims 1 to 12, characterized in that a prefabricated combination of a flow agent and fibers is used. I'll be 30.

14. Device for the production of gypsum boards for carrying out a method according to one of claims 1 to 13, characterized in that the device is equipped with a spreading device. -10-2025-43878401 -Hau ptpost-0040 06- 10-2025-43878401-H awP What t -0040 PCT / DE2025 / 000098 15. Device for producing a gypsum mixture as a spreadable and fast-drying plaster mixture according to a method according to one of claims 1 to 13. 5 16. Gypsum board with a gypsum board core or at least one layer of gypsum, characterized in that at least the gypsum board core or the at least one layer is produced according to a method according to one of claims 1 to 13. 10 17. Gypsum board according to claim 16, characterized in that it is produced on a spreading and forming system for cement-bonded wood fiberboards or cement building boards. 15 18. Spreadable plaster of Paris mixture, produced by a process according to any one of claims 1 to 13.

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