DE1914612A1 - Fire-resistant fibreboard of asbestos and - wood fibre - Google Patents

Abstract

Composite fibre board is manufactured by continuous production of (a) a layer of moist wood fibres, (b) a layer comprising moist asbestos fibres and wood fibre slurry, pref. also including starch, above first layer. Both layers are then bonded together with expulsion of the water.

Description

Fire retardant fibreboard and method of making it The invention relates to fire retardant fibreboard and processes for their manufacture. Fiberboard with fire-retardant properties, for example according to Class I according to the British Standard B.P. 476 are obtained and are made using the finished plate is subjected to a further process such as chemical impregnation. This has the disadvantage that the £ is usually outside the monitoring of the Plate manufacturer sets, and here a plate is produced, which according to the Treatment to give the fire retardant properties over the same Plate is markedly inferior before treatment.

panels made in this way lose much of their strength, the rate of water absorption is greatly increased and the surface of the panels is increased are often with crystal cut off in the processing to make them fire retardant chemicals used defaced.

One known method of making fiberboard includes Steps: the logs are fed to a chopping machine, which chopping the logs crushed, transfer of the wood chips in a defilrator in which the wood chips at pressures up to au 12 (170 lbs./sq. in.) are treated with steam before closing Device for shredding the wood chips are fed into individual whey barrels, Transfer of the resulting mixture of wood fibers and water - the following is referred to as fibrous - to a thickener, which a certain percentage of the water removed, treatment of the pulp in a refinier, the larger ones Fibers chopped up and thereby a consistently fine fiber pulp is produced, feed of the fined pulp into a container or chamber where the fined pulp Chemicals (which usually contain aluminum sulfate) are added, transfer of the chemise-treated pulp into a cyclone, in which foreign particles such as E.g. sand or splinters are removed, transfer of the appropriate pulp in a head box or single hopper of a mat forming machine, from where the Is applied evenly fiber-free to an endless sieve belt, which is located under moved the headbox, and through which water from the gravity Pulp flows off as soon as the plates take shape, applying a vacuum suction under the main belt at three points to support the dewatering process, Passing the wet fiber mat between pressure rollers, subsequent cutting of the continuous wet fiber mats - hereinafter referred to as stratification - in plates, laying each of these wet layers on a steel wire mesh, which is located on a support plate made of mild steel, transfer of the support plates in a receiving magazine, in which the carrier plates are stacked on top of each other, Transfer of the Magazine after loading into a hydraulic press, around dry, dense plates of approximately 1/8 the thickness of the wet fiber mat, see below Produce, placing the plates in an oven, in which they are for several hours at high temperatures are exposed, transferring the plates to humidification chambers, in which the plates Absorb moisture under controlled conditions and then cut up the plates to the predetermined sizes.

The invention avoids the aforementioned disadvantage and provides a Process for the production of fire-retardant fibreboard, which involves shaping a moving layer of wet wood fibers in a continuous manner, the continuous Forming a wet asbestos pulp and pulp containing layer on top of one Surface of the 4-layer wood fiber during the forward movement and the subsequent one Removal of water from the two layers includes the two layers connect and unite.

Preferably, starch is present along with the asbestos fibers in order to to support the connection of the asbestos fibers with the wood fiber. So far has been Only asbestos is mentioned in the description, but other materials can also be used that are chemically inert six, for example gliners. -The invention also relates to Expensive fibreboard, namely composite panels, the two in the manufacturing process of the composite plate have interconnected layers, one of which Layer of Eols fibers and the other layer of a mixture of wood fibers, Asbestos fiber and starch.

The surface of the wood-asbestos layer is advantageously with Treats fire retardant chemicals, some of which penetrate the wood fiber layer.

The invention is explained in more detail below, with the description is to be considered as an example.

the new feature of the inventive method is that a second Headbox in the aforementioned mat forming machine above the endless one sieves and in front of the point at which the vacuum is applied. A mixture of wood fiber, asbestos fiber, starch and water is used in this second Filled casserole, from which it is in the form of a layer on the damp Mat made of wood fibers, which were generally formed by the mat forming machine, was applied will, and the top surface of the stratification will be subsequent to passing the pressure rollers are sprayed with a chemical, some of which through the Absent wood layer penetrates to the wood fiber layer. The presence of strength ensures that the hol2 and asbestos fibers connect with each other.

The chemical advantageously contains a. Mix in water dissolved borax (trademark Polybor), urea (trademark Urea FX) and formalin, and the chemical is sprayed onto the outer surface of the asbestos wood layer, from where it penetrates to the wood fiber layer.

The chemically treated pre-fret plate is then preferably with a Tall oil emulsion sprayed, showing any tendency of the plate, on the surface plate sticking after compression in the hydraulic press prevents.

The asbestos fiber and wood fiber mixture is produced by 1,140 250 gallons (1) of water to 50 lbs. (22.7 kg) of asbestos fiber to form an asbestos slurry added, 13.6 kg (30 lbs.) of fiber at mixed in 680 liters (150 gall.) of water are completely mixed, the asbestos slurry and the diluted pulp and 1.8 kg (4 lbs.) starch are added with the starch added 8% of dry soil on asbestos fibers.

The blending of the asbestos fibers, wood fibers and starch is done in one Container or box is made and the mixture is applied to the surface of the wet Fiber pulp mat with the interposition of the aforementioned second headbox applied so that 3.2 kg (7 lbs.) of asbestos (based on dry asbestos) is evenly distributed spread over 7.4 m² (80 sq.ft.) of the wet bar.

The amount given above would therefore be sufficient to cover approximately 52m² (560 sq.ft.) to cover.

Preferred proportions in the chemical mixture are 10.4 kg (23 lbs.) Borate (Trademark Polybor), 14.1 kg (31 lbs.) Urea (Trademark Urea FX) and 3,400 cc formalin (15% methanol), with the addition of water to form a Mixture of 51.2 liters (11.25 gallons). The chemical solution is advantageous in an amount of 9.1 liters (2 gallons) by 5.6 m (18 ft. 4 in.) of wet bedding applied.

Other chemicals besides those mentioned above that have fire retardant properties can also support the fire-retardant properties Solution can be used. Furthermore, the proportions of the substances used can be changed and varied to meet special needs.

Main advantage of composite panel; manufactured according to the invention is that when exposed to flames, the wood fibers in the finished Asbestos wood surface char and together with the asbestos an insulation opposite the heat.

A composite fiber board according to the invention is shown schematically in the drawing shown. Here: 1 means that essentially only consists of wood fibers 3 Layer of the board, 2 the second layer of the board, the wood fibers 3 and asbestos fibers 4 as well as preferably thickness anthät and 5 the line at which both layers with each other connected and united.

In the particularly preferred embodiment, the plate still contains fire-retardant or flame-retardant chemicals, predominantly in layer 2 with a concentration gradient from the top of layer 2 to layer 1, which is less and less saturated downwards.

- patent claims -

Claims (6)

Claims 1. Process for the production of fire-retardant fibreboard, thereby g e k e n n n s c i c h n e t that a moving layer of wet Wood fiber is produced in a continuous manner on one surface of this wood fiber layer a layer of wet asbestos fibers is continuously created while moving and wood / pulp and then water from the two layers below Connection and union of the two layers with one another is removed. 2. The method according to claim 1, characterized in that g e k e n n n z e e i c h -n e t that the surface of the wood acbest layer with one or more fire retardant Chemicals being treated. 3. The method according to claim 2, characterized ge k e n n s e i c h -n e t that the surface of the wood-asbestos layer so with an aqueous solution of a or several fire retardant chemicals are sprayed that something down to the wood fiber layer penetrates. 4. The method according to any one of the preceding claims. thereby g e no indication that the mixture of substances forming the asbestos-wood fiber layer Starch is added. 5. Fire-retardant fibreboard, which means that it can be used that this is a composite panel, the two during the manufacturing process the composite panel has unified layers, one of which consists of Wood fiber and the other layer made of a mixture of wood fiber, asbestos fiber and strength exists. 6. Fire-retardant fiberboard according to claim 5, characterized in that g e k e n n I can tell that they are made of hols fibers. Asbestos fibers and starch existing layer with one or more impregnated with fire retardant chemical (s).