FI64129B - FRAMSTAELLNING AV EN BYGGNADSPLATTA ENLIGT UPPRULLNINGSFOERFARANDET - Google Patents

Description

• ASST *] [B] (11) ANNOUNCEMENT

jmar- ij utlAggn i ngsskrift 64i29? p3 | C? S: nl -A'C'l & t '' ^ ^ ^ ^ ^ (Si) Kv.fc.Wci.3 C 04 D 31/36 FINLAND —FINLAND (21) Pu.nttiMk.mui-IWwM-eimif, * (22) HikwnispUvi - AmOknlnfxfcc jf>. 05. 80 (23) Alkupfcvl — GIMfhMdac 30.0 ^ .00 (41) Tullut lulkiMicd - Bllvtt off * ntH | 01.12.8l

Pktantti. and the National Board of Registration} NlhtivUuipM> on „klKlL) ulluJwn 30 o6 83

Patent · och registerstyrelsen Amefcui uttogd och utUkrWMn puMicand '(32) (33) (31) Requested MuoilcMt — Baglrd priorltut (71) Oy Partek Ab, 2l600 Parainen, Finland-Finland (FI) (72) Kauko Ensio Junkkarinen, Muijala, Finland -Finland (FI) (7M Berggren Qy Ab (5 * 0 Building board production by corning method -

Framstalining av en byggnadsplatta enligt upprullningsforParandet

The invention relates to the production of a building board by a collection method in which the wet pulp of the board uses ground cellulose and / or waste paper fibers as carrier fibers, waste gypsum in the dihydrate form as a filler and hydraulically curable cement as a binder and additives.

Finnish patent application 762484 discloses the production of an asbestos-free building board by a collection method in which unopened or non-ground cellulosic fibers and / or waste paper are used as wet pulp carrier fibers, cement as a binder and, among some other substances, gypsum as part of the process. However, according to the method, the process is allowed to continue until the hemihydrate is virtually completely converted to the dihydrate before the wet mass is collected into a sheet.

According to application 762484, uncalcined waste gypsum can also be used. However, the present application does not disclose at all 2 64129 the relationship between the degree of opening of gypsum and cement and cellulose fibers (unopened fibers) in accordance with the present invention. Attempts to make building boards using unopened, i.e. unground, cellulosic fibers have not been satisfactory in practice because such untreated fibers do not hold the wet mass components, especially waste gypsum and binder, cement, evenly together. However, cohesiveness is essential, especially when using the collection method.

According to the present invention, it is intended to use waste gypsum for the production of fire-resistant building boards by a collection method. Waste gypsum is becoming a real problem, as it is formed in quite large quantities in some industries, such as the phosphate industry. In Finland, waste sparks are formed about 1 MB per year. The recovery of such an amount of waste is of great economic importance.

Experiments have shown that it is the grinding of pulp fibers that allows the use of waste gypsum in building board, although the waste gypsum itself does not bind. Namely, grinding causes "felting", i.e. a structure in which the fibers adhering to each other form a cavity. When these are filled with some compressed material that does not need to be chemically bonded, a surprisingly rigid structure is created. This substance can be waste gypsum, which thus acts as a mere filler. The phenomenon may be caused by surface forces between particles. Van der Waal force or other similar forces that hold particles together in cavities. In this way, very good boards can be made, which are well suited for interior cladding.

The mechanism that holds the disk together is not exactly known.

The strength of the building board thus obtained is, of course, not as good as the strength of a board made with known binders, but it is still surprisingly good. As such, however, the sheet is not waterproof and is soluble in water. For this reason, some hydraulically curable cement must be added to the mixture. Thus, cement is not intended to provide

II

3 64129 structures which allow the transfer of forces, as this is achieved by means of ground cellulose fibers and waste gypsum. Since the purpose of the cement is only to prevent the plate from dissolving, its proportion can be minimized. The amount of cement depends essentially on the other materials used, especially the waste gypsum.

By relating the degree of opening of the fibers and the amounts of gypsum and cement to each other in the correct way found through the experiments, a board which is water-resistant and has satisfactory strength properties is obtained. Since the proportion of cement can be minimized, the proportion of gypsum important for fire resistance can be maximized. Thus, a utilizing use has also been found for waste gypsum.

According to the invention, opened cellulose and / or waste paper fibers are used as carrier fibers in the production of waste gypsum as carrier fibers, the degree of grinding of which must be relatively high, 20-75 ° SR (Schopper-Riegler). The amount of hydraulically curable cement used as a binder is 10-50% of the total dry weight of the board, while the amount of waste gypsum is 20-80%, respectively. The amount of cement used depends on the degree of opening of the cellulosic fibers. Since uncalcined waste gypsum does not bind hydraulically, the use of cement is therefore important. In the method according to the invention, it is also important that the degree of opening of the carrier fibers and the amounts of gypsum and cement are advantageously related to each other in order to achieve the optimum result.

The features of the invention appear from the following claim. According to it, in addition to the above-mentioned materials, blast furnace slag and fly ash as well as silicon, perlite, vermiculite, limestone powder and the like are used for the building board, and further mineral fibers, glass fibers, glass, lining and slag wool and other materials and organic fibers: sisal, sisal and plastic fibers and the like, as well as flocculants to the extent indicated in the claim.

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The building board produced by the method according to the invention using uncalcined waste gypsum has completely satisfactory strength properties, although not all strength values are of the same class as with previously produced boards.

Instead of waste gypsum, the method according to the invention can of course also be used to produce building boards in which the starting material is uncalcined raw gypsum.

The following table shows, for comparison, some test results showing the strength properties of building boards made by the method according to Finnish patent application 762484 and the strength properties of building boards made by the method according to the present invention.

I: 5 64129

Composition Density Bending strength Impact strength Huan.

kg / m2 N / nm2 per Nmra / nm3. driving position. driving- driving- driving- driving- heading-. vast, nassa mouth. vast, nassa

Pulp fiber 15%

Gypsum »fed 50% 1119 9.6 19.3 3.4 7.0 as hemihydrate

Cement 35% - 762484

Pulp fiber 15%

Gypsum, fed 42% 1113 12.2 26.1 2.5 5.7 as a hemihydrate

Cement 15%

Min.additives 28%

Pulp fibers 10% Waste gypsum 60% 1415 13.6 16.8 2.1 3.1 On display

Cement 30% inventive

Pulp fibers 10% to Waste gypsum 60% 1311 15.4 19.2 2.3 3.5

Cement 10%

Slag 20%