Method of manufacturing of gypsum fiberboards with textile fiber material

Abstract

The invention relates to a method of manufacturing of gypsum fiberboards including the step of providing a fiber material which comprises providing textile fiber dust material. Further, the invention relates to a gypsum fiberboard comprising gypsum material and a fiber material comprising textile fiber dust material.

Description

[0001] Method of manufacturing of gypsum fiberboards with textile fiber material

[0002] The invention relates to a method of manufacturing of gypsum fiberboards and a gypsum fiberboard.

[0003] The invention pertains to the technical field of the production of gypsum fiberboards with reinforcing fibers.

[0004] Gypsum fiberboards are widely used in drywall installations, especially for wall- and ceiling panelling. In comparison to gypsum plasterboards, they offer better fire protection, higher stability and are less susceptible to negative influence by humidity.

[0005] The difference between gypsum fiberboards and plasterboards is the alternative structure. The plasterboard has a core of gypsum coated in cardboard, while the gypsum fiberboard is a homogeneous board made from fiber reinforced gypsum.

[0006] The properties of gypsum fiberboards like the fire resistance, water vapour permeability, bending strength, and thermal permeability are the subject matter of DIN EN 15283-2. According to it, a board with a thickness lower than 18 mm must have a bending strength of 5.5 N / mm2. However, a board with a thickness higher than 18 mm must have a bending strength of 5.0 N / mm2. These limits are fulfilled by gypsum fiberboards with cellulose fibers.

[0007] A method of manufacturing gypsum fiberboards with cellulose fibers is known from EP 3 013 768 B1.

[0008] The cellulose fibers used for manufacture of gypsum fiberboards can be environmentally friendly produced from recycled paper. However, because the cellulose is a resource with multiple different applications, it is expensive and occasionally scarce. To reduce the dependence on cellulose fibers an alternative type of fiber for the environmentally friendly manufacture of gypsum fiberboards is needed.

[0009] It is known that textile fibers are produced in the process of recycling used textiles. These fibers, however, are significantly longer and rougher than cellulose fibers made from recycled paper. Consequently, these textile fibers are generally not regarded to be suited to replace cellulose fibers in a gypsum fiberboard.

[0010] Therefore, it is the object of the invention to overcome the disadvantages of the state of the art and especially to provide a method of manufacturing gypsum fiberboards which contains at least an alternative type of fiber to cellulose fibers and is thus less dependent on the availability of recycled paper.

[0011] This object is solved by a method of manufacturing gypsum fiberboards and a gypsum fiberboard according to the respective independent claim. Advantageous embodiments are subject matter of the respective dependent claims.

[0012] The invention comprises a method of manufacturing a gypsum fiberboard comprising the steps of

[0013] - providing calcined gypsum material;

[0014] - providing a fiber material;

[0015] - mixing in a wet process the calcined gypsum material with the fiber material and water in a mixer to provide the mixture on a transport belt to obtain a moistened gypsum fiber mixture; or

[0016] - mixing in a dry process the calcined gypsum material with the fiber material to provide the mixture on a transport belt and adding water to obtain a moistened gypsum fiber mixture;

[0017] - reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material; cutting the gypsum fiberboard material to a predetermined size and shape to provide the gypsum fiber board; wherein the step of providing a fiber material comprises providing textile fiber dust material.

[0018] In the first alternative of the wet production process (Hatschek-Process), the method for manufacturing (producing) a gypsum fiberboard comprises the steps of providing calcined gypsum material (also called stucco or plaster of Paris, that includes mainly beta hemihydrate. However, calcined gypsum material can also contain minor amounts of other calcium sulphate modifications such as alpha-hemihydrate, anhydrite HU, anhydrite IIS, anhydrite III, dihydrate or mixtures of two or more of the above modifications as well as carbonates or other minerals may be present in minor amounts in the calcined gypsum material as well), providing a fiber material, introducing the calcined gypsum material together with the fiber material into a mixer and adding water, applying the moistened mixture of calcined gypsum material and fiber material to a movable transport belt and pressing the moistened mixture to obtain a gypsum fiberboard strand from which the gypsum fiberboards are cut. In the second alternative, the dry production process (Siempelkamp-Process), the method for producing a gypsum fiberboard comprises the steps of providing calcined gypsum material mixed with a fiber material, laying the calcined gypsum material together with the fiber material onto movable transport belt and adding water. A vacuum (under pressure) is applied through the movable transport (filter) belt to reduce the water from the moistened mixture to obtain a gypsum fiberboard material from which the gypsum fiberboards are formed (e.g. by cutting).

[0019] In both alternatives, the fiber material comprises textile fiber dust material which is a textile fiber material having only dust-like short fibers therein so as to appear as fibrous dust material. The range of the (median) fiber length is advantageously below 4 mm, in particular below 2 mm, and will be defined with preferred ranges in the following. Compared to the known use of cellulose fibers that means that at least some of the cellulose fibers can be replaced in the gypsum fiberboard. The need for cellulose fibers is reduced by including at least one alternative type of fiber, and the environmentally friendly production becomes less dependent on the availability of wastepaper.

[0020] According to an advantageous aspect, the step of providing the fiber material comprises providing the textile fiber dust material from the reprocessing of textiles. In fact, it has been shown that the recycling of used textiles produces a textile fiber dust material as a by-product, which has similar properties (e.g. wettability, mechanical strength) to cellulose.

[0021] Preferably, the reprocessing of textiles comprises the steps of:

[0022] - defibering textiles into a defibered portion and a textile fiber dust material portion; and

[0023] - rejecting the defibered portion from the textile fiber dust material portion.

[0024] The reprocessing of the textiles comprises the steps of defibering textiles in a defibered fraction (which contains fibers of up to several cm of length) and a textile dust fraction and sorting out the defibered fraction from the textile dust to provide the textile fiber dust material. The defibered portion is too coarse and not suitable for use in a gypsum fiber board. The textile dust portion is similar to wastepaper fibers and is suitable as fiber material and in particular as a substitute for cellulose fibers. The textiles can come from used clothing collections or industrial waste, for example.

[0025] Advantageously, the textile fiber dust material comprises fibers of plant or animal origin, synthetic fibers, regenerated fibers or mixtures thereof. The use of a variety improves the independence from a single product. In addition, some of the textile fiber material used in this process is now thermally recycled, meaning that its use in a gypsum fiberboard is a sustainable alternative to other uses for the resource.

[0026] It is particularly preferred that the textile fiber dust material comprises textile fibers with a length in the range of 0,001 mm to 4,0 mm or in the range of 0,001 mm to 3,0 mm or in the range of 0,5 mm to 4 mm, in particular in the range of 0,02 mm to 2,5 or in the range of 0,02 mm to 2,0 mm or in the range of 0,7 mm to 2,5 mm.

[0027] Preferably, the textile fiber dust material comprises textile fibers with a length distribution in the ranges of

[0028] 3 - 4 mm: 2 to 4 %;

[0029] 2 - 3 mm: 8 to 10 %;

[0030] 1 ,2 - 2 mm: 13 to 19 %;

[0031] 0,6 - 1 ,2 mm: 20 to 30 %;

[0032] 0,2 - 0,6 mm: 15 to 25 %; and 0 - 0,2 mm: 20 to 30 %.

[0033] Advantageously, the fiber material has a proportion in the range of 5 weight percent to 20 weight percent relative to the calcined gypsum material, preferably in the range of 13 weight percent to 16 weight percent.

[0034] Preferably, the calcined gypsum material is provided with a (liquid) hydrophobizing agent.

[0035] Advantageously, the step of reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material comprises applying a vacuum through a filter transport belt.

[0036] In an alternative aspect, the step of reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material comprises to apply a continuous pressure via a press.

[0037] In both alternatives, the step of reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material comprises the increase of reduction of water in a predetermined time by increasing the amount of textile fiber dust material. That means that during a predetermined time (e.g. when starting the application of a pressure), the amount of water exiting from the mixture can increase due to increasing textile fiber dust material proportion. In experiments, during the first 30 seconds after the application of a pressure, a 20 % increase of the reduced water compared to the identical proportion of cellulose fibers has been achieved.

[0038] A further aspect of the invention comprises a gypsum fiberboard (preferably manufactured according to the method described herein) comprising gypsum material and a fiber material, wherein the fiber material comprises textile dust fiber material. The manufacture of this gypsum fiber board is in particular more independent of the availability of cellulose fibers. It has been shown that the partial use of textile fiber dust material results in a bending tensile strength of the gypsum fiber board which differs only marginally from a gypsum fiber board with pure cellulose fiber material.

[0039] Preferably, the gypsum material comprises FGD gypsum and / or natural gypsum. The gypsum material in the gypsum fiberboard is cured (i.e. rehydrated) calcined gypsum material (also called stucco or plaster of Paris, that includes mainly beta hemihydrate. However, calcined gypsum material can also contain minor amounts of other calcium sulphate modifications such as alpha-hemihydrate, anhydrite HU, anhydrite IIS, anhydrite III, dihydrate or mixtures of two or more of the above modifications as well as carbonates or other minerals may be present in minor amounts in the calcined gypsum material as well). Advantageously, the fiber material has a proportion in the range of 5 weight percent to 20 weight percent relative to the calcined gypsum material, preferably in the range of 13 weight percent to 16 weight percent.

[0040] Preferably, the fiber material comprises cellulose fibers, mineral fibers, synthetic fibers or mixtures thereof and has a proportion of 2% to 100% of the textile fiber dust material. With a proportion of 100% textile fiber dust material, no cellulose fiber (or other fiber material) at all is required for the production of the gypsum fiberboards.

[0041] Advantageously, the gypsum fiberboard has a density of 1000 kg / m3to 1600 kg / m3, preferably 1 100 kg / m3to 1250 kg / m3. The density has an influence on properties such as sound insulation or mechanical stability and / or durability.

[0042] In the following, the invention will be explained in more detail with reference to an exemplary embodiment of a gypsum fiberboard according to the invention manufactured using the method according to the independent method claim. The exemplary embodiment is a gypsum fiber board with a thickness of 12.5 mm, a density of 1200 kg / m3and a fiber material content of 16 % of the total weight of the calcined gypsum material (which is close to the gypsum fiber board weight). The fiber material contains 50 % textile fiber dust and 50 % cellulose fibers. The gypsum fiberboard was manufactured using a dry process (Siempelkamp process).

[0043] In several laboratory tests according to DIN EN 15283-2, it has been shown that gypsum fiberboards according to the exemplary design have a flexural tensile strength of 6.1 N / mm2to 6.3 N / mm2. This measurement shows that the gypsum fiberboard according to the invention with a textile fiber dust content of 50 % meets that specific standard.

[0044] Further, a thermogravimetric analysis was carried out to investigate the influence of temperature on the textile fiber dust with a device for thermogravimetric analysis (TGA550 from TA Instruments). It was surprisingly found that the textile fiber dust starts burning slightly later (approx. 17%) than the cellulose fibers. This can be seen in Fig. 1 . The big loss of weight (which means that it is burnt) starts for the cellulose fibers at 253,69 °C, while it starts for the textile fiber dust at 296,73 °C. Also, up to 600 °C the textile fiber dust is more stable and decays slower.

[0045] Advantageously, the textile fiber dust material also has a slightly higher thermal stability than the cellulose fibers. This can be helpful when qualifying gypsum fiberboards for fire resistance.

[0046] In the following, the invention will be explained in more detail with reference to Fig. 2 which shows the result of an analysis of the reduction of water during the manufacturing for an exemplary embodiment of a gypsum fiberboard manufactured according to the invention.

[0047] In this study, a gypsum fiber mixture consisting of 90 % calcined gypsum and 10 % fibers was tested. Two types of fibers were compared with each other: Textile fiber dust and paper fibers (i. e. cellulose fibers). The aim was to find out how well water can be absorbed by the mixture and how the different fiber types affect the water permeability.

[0048] Test set-up:

[0049] A defined amount of water was poured onto the gypsum fiber mixture from above. The water was sucked through the gypsum fiber mixture using a suction device that generates a negative pressure of up to 0.5 bar (simulating the vacuum through the filter transport belt). The extracted water was collected in a flask placed on a scale. This allowed the amount of water sucked through to be measured precisely.

[0050] The results:

[0051] The test results show that the water could be sucked through the mixture faster in the sample with textile fibers than in the sample with paper fibers. Paper fibers bind the water more intensively, causing it to flow more slowly through the mixture. Textile fibers dust, on the other hand, bind less water and release it more quickly.

[0052] The conclusion:

[0053] The gypsum fiber mixture with textile fibers dust requires less water and also releases it more quickly. This could be used in practice to reduce the amount of water required in production and to make drying processes more efficient.

Claims

Claims1 . A method of manufacturing a gypsum fiberboard comprising the steps of- providing calcined gypsum material;- providing a fiber material;- mixing in a wet process the calcined gypsum material with the fiber material and water in a mixer to provide the mixture on a transport belt to obtain a moistened gypsum fiber mixture; or- mixing in a dry process the calcined gypsum material with the fiber material to provide the mixture on a transport belt and adding water to obtain a moistened gypsum fiber mixture;- reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material;- cutting the gypsum fiberboard material to a predetermined size and shape to provide the gypsum fiberboard; wherein the step of providing a fiber material comprises providing textile fiber dust material.

2. The method according to claim 1 , wherein the step of providing the fiber material comprises providing the textile fiber dust material from the reprocessing of textiles.

3. The method according to claim 2, wherein the reprocessing of textiles comprises the steps of:- defibering textiles into a defibered portion and a textile fiber dust material portion; and- rejecting the defibered portion from the textile fiber dust material portion.

4. The method according to any one of the preceding claims, wherein the textile fiber dust material comprises fibers of plant or animal origin, synthetic fibers, regenerated fibers or mixtures thereof.

5. The method according to any one of the preceding claims, wherein the textile fiber dust material comprises textile fibers with a length in the range of 0,001 mm to 4,0 mm or in the range of 0,001 mm to 3,0 mm or in the range of 0,5 mm to 4 mm, in particular in the range of 0,02 mm to 2,5 or in the range of 0,02 mm to 2,0 mm or in the range of 0,7 mm to 2,5 mm.

6. The method according to any one of the preceding claims, wherein the textile fiber dust material comprises textile fibers with a length distribution in the ranges of3.2- 4 mm: 2 to 4 %,2-3,2 mm: 8 to 10 %,1 .2-2 mm: 13 to 19 %,0,6-1 ,2 mm: 20 to 30 %,0,2-0, 6 mm: 15 to 25 % and0-0,2 mm: 20 to 30 %.

7. The method according to any one of the preceding claims, wherein the fiber material has a proportion in the range of 5 weight percent to 20 weight percent relative to the calcined gypsum material, preferably in the range of 13 weight percent to 16 weight percent.

8. The method according to any one of the preceding claims, wherein the fiber material further comprises cellulose fibers, mineral fibers, synthetic fibers or a mixture thereof.

9. The method according to claim 6, wherein and the textile fiber dust material portion is in the range of 5 to 100 weight percent, in particular in the range of 30 to 60 weight percent, of the fiber material portion.

10. The method according to any one of the preceding claims, wherein calcined gypsum material is provided with a hydrophobizing agent.1 1. The method according to any one of the preceding claims, wherein the step of reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material comprises applying a vacuum through a filter transport belt.

12. The method according to any one of the claims 1 to 10, wherein the step of reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material comprises to apply a continuous pressure via a press.

13. The method according to any one of the claims 11 or 12, wherein the step of reducing the water in the moistened gypsum fiber mixture by applying a pressure to obtain a gypsum fiberboard material comprises the increase of reduction of water in a predetermined time by increasing the amount of textile fiber dust material.

14. A gypsum fiber board comprising gypsum material and a fiber material comprising textile fiber dust material.

15. The gypsum fiberboard according to claim 14, wherein the fiber material is only of textile fiber dust material.

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