HUT64926A - Plastering fibre-plate comprising cellulose base bibre-sludge and process for producing of the fibre-plate - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a gypsum bonded fibreboard containing cellulose-based fibrous sludge and to a process for making the fibreboard.

According to the literature, industrial production of gypsum board began in the United States in 1912 and in the Federal Republic of Germany in 1948. Fiberglass reinforced gypsum boards have been produced since 1960 in the German Democratic Republic. Since 1971, paper has been produced in the Federal Republic of Germany using waste paper / G. Kossatz;

K. Lempfer: Zür Herstellung Gipsgebundener Spanlatten in einem Halbtrockenverfahren Holz als Roh- und Werkstoff 40. / 1982 / 333-337. She./.

• Λ ·

- 2 The first industrial plant for the production of gypsum-bonded particle board / 1985 / was built by Saastamainen Oy Kuopio for the Finnish company BISON / GSK. /H.G. Schwarz: Industrielle Produktion gipsgebundener Spanplatten in einer neuen Anlage in Finnland Holz als Roh- und Werkstoff 44/1986 / 365-387. She./.

The widespread production of gypsum board is hampered by the fact that

- the very high quality requirements for special cover layers used on both sides of a sheet can only be met economically by paper mills with great difficulty.

- special board for gypsum board. gluing with corn starch, which is not permitted in some countries for construction purposes,

- the so-called souvenir used in sheet making. due to the wet process, adjusting the final moisture content of the finished product requires significant drying capacity.

In the case of fiberglass reinforced gypsum fiber boards, the process of crushing and mixing / homogenizing the fiberglass causes technological difficulties.

Fibreboard sheets utilized in the process described in U.S. Patent No. 164,419 have very favorable properties, but require the use of pure, graded plastic, silicate and non-metallic newsprint materials.

It is known that

- the paper industry suffers from a significant shortage of pulp and needs to be replaced by a large quantity of waste paper, and

- the task of cleaning and sorting waste paper entails a significant additional cost,

- the fibreboards are produced by a press, a very expensive machine,

- the waste paper is present in the fibrous sheets as non-filamentous fibers, which reduces the homogeneity of the sheets.

The disadvantages of gypsum-bonded particle boards besides their favorable properties are:

- the reiative has a high wood content (25-28%), which requires the use of mainly bark fir. Namely, decomposing organic acids / tannic acid / / and inlaying materials from deciduous trees delay the solidification / hydration of the gypsum and thus reduce the bond strength / M.H. Simatupang; Lu Xi Xian: Einfluss einiger Holzarten auf die Hydration des Gipses Holz als Roh- und Werkstoff 43. / 1985 / 118.0./.

- max. Can contain 15% bark because the bark has more bonding material than the wood,

- wood chipping and regurgitation appear as a separate cost factor in the process,

- recent research has shown that the binding of gypsum to wood shavings particles is adversely affected by the swelling of the gypsum during hydration and the shrinkage of the wood during drying, which breaks down existing bonds.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gypsum-bonded fibreboard which, while retaining the advantages of the known solutions, eliminates the disadvantages of the manufacturing technology, the properties of the raw material used in addition to the gypsum and the cost of manufacture.

The present invention is based on the discovery that cellulose-based pulp sludge, which is a major environmental problem due to its large amount in the papermaking industry, can be used for the preparation of low-cost, high-quality, easy-to-handle construction fiber boards after proper preservation and stabilization.

It is an object of the present invention that the fibreboard is 60-90 SR °, 8-15% dry solids sludge and 750-1250 kg gypsum and 1% biocide and preferably a gassing additive, which is produced as a papermaking waste. , for example, aluminum sulfate (Α12 ₂ (5ΟΟ) ₃ ) and / or calcium chloride (CaClCl).

It is a further object of the present invention to process pulp of 60-90 SR ° as a papermaking waste in a manner known per se to produce 8-15% dry matter in the slurry, to add to the slurry the additive for preserving and stabilizing the sludge, the biocide. 750 to 1250 kg of gypsum per minute and dispersing the elemental fibers of the sludge sludge with vigorous stirring in the gypsum system, preferably spreading the resulting dispersion system of W = 0.60-0.85 water gypsum on an infinite mesh belt, preferably by continuous sieving, applying a vacuum of 0.1-0.05 MPa and a pressure of 0.5-2.0 N / mm on one or both surfaces of the tablecloth until hydration of the gypsum is complete.

The sludge from the papermaking processes is subjected to post-treatment and filtration. During filtration, the waste that is still usable is recovered, while the non-recoverable materials are transferred to the sludge. During repeated use of the paper, the fibers are so fine that they are added to the sludge.

There is no sharp boundary between the fibers that can and cannot be used in papermaking, as this is always a function of the size of the mesh used in the filtration. The re-usability of the fibers is best determined by the degree of grinding, which indicates desiccation. The milling fibers range from 10-12 SR ° to 40-60 SR °. The degree of grinding of the paper sludge, which cannot be used in paper making, is 60-90 SR °. This sludge contains many contaminants, paints and preservatives.

The sludge is composed of elemental fibers and can be dehydrated very poorly.

Due to the large volume generated, as only a small part is currently utilized for agricultural purposes, its storage poses a significant environmental problem.

The processing of fibrous sludge as gypsum bonded fibreboard is a positive solution to the environmental problem, since the otherwise poorly dehydrated sludge removes, removes water from the gypsum reaction, and the elemental fibers of the sludge are homogeneously distributed in the sheet in terms of strength.

The preservation and stabilization of the sludge sludge can be accomplished by adding a biocide to prevent bacterial degradation.

The biocides to be used in paper mill treatment of fibrous sludge - e.g. 25 preservatives and 90 preservatives should be applied alternately weekly to eliminate the conditions of the ever-changing large number of microorganisms.

In order to improve the thermal insulation properties of gypsum-bonded fibreboard and to achieve a lower bulk density (950-1000 kg / m), aluminum sulphate in aqueous solution or crystalline form is used as a gas-forming but also strength-enhancing material.

4.5-6.0 to ensure pH.

The importance of aluminum sulfate addition is that:

- it can form a coordination bond on the hydroxyl and carboxyl groups of the fibers, and

due to the high surface area charge of the resulting aluminum hydroxide / AKCH2 / Gel, it forms a bridge between the fiber and the gypsum crystal and is formed by the carbonate hardness of the water, i.e. the presence of hydrocarbonates.

- the gypsum calcium carbonate / CaCO ^ / content, by reacting with the aluminum sulphate plus gypsum crystal growth - in strength - in addition lead dioxide / C0 ₂ / gas formation, which results in the formation of air pockets in the structure of the sheet preferably thermal point of view during the gypsum hydration.

I. A1 ₂ (SO ₄ ) ₃ + 6 H ₂ O j ₂ Al (OH) ₃ + ₃ SO ²

II. 2H ⁺ + 2CaCO3 * 2Ca ²⁺ + H20 + C0 ₂

III. Ca ²⁺ + S0 ₄ CaSO ₄ + 6H ⁺

The excess aluminum sulphate is reacted with a solution of calcium chloride / CaCl ₂ , which results in further gypsum crystallization and porosity increase:

ARC. A1 ₂ (SO ₄ ) ₃ + 3 CaCl ₂ -> 3 CaS0 ₄ + 2 AlCl ₃

V. A1C1 ₃ + H ₂ 0 * Al (OH) ₃ + 3 HCL

VI. CaCO ₃ + 2 HCL + CaCl ₂ + H ₂ 0 + C0 ₂

Calcium chloride may also be added in the form of a crystalline suspension.

According to the invention, it is expedient to add the aluminum sulphate and / or calcium chloride solution or crystal to the fiber sludge containing the 11-13% solids biocide immediately before the gypsum is added.

The elemental fibers of the fiber sludge are dispersed in the gypsum system by vigorous stirring and the resulting slurry of W = 0.6-0.85 water gypsum is spread over an endless plastic web. After pouring, use a continuous screen press on one or both surfaces of the table setting

A vacuum of 0.1 to 0.05 MPa and a pressure of 0.5 to 2.0 N / mm were used.

Using vacuum and press pressure, we try to reduce the water-gypsum factor of the tableware to a minimum,

- the water-gypsum factor W = 0.4 used for semi-dry technology, which is

increase in strength of the fiberboard, and

- leads to a reduction in drying energy.

Pressing should be done under pressure until the plaster is hydrated / cured / finished. The feed rate of the tableware is thus closely related to the completion of the crystallization process in the press.

The endless gypsum bonded fibreboard from the screen press is preformed to the required size lengthwise and transversely. The pre-formatted sheets are dried in a drying apparatus to a moisture content of 9 ± 3% and air-conditioned.

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- 9 Adjusting the final thickness of the sheets - is done with a contact belt sander on one side. Hydrophobization is carried out on demand. After the resulting gypsum fiber abrasive powder has been removed, it is reused as a bond accelerator to form the fiber-gypsum suspension.

The process of the invention will now be described in more detail by way of exemplary embodiments.

Example 1

3 pulp sludges with a dry content of 3.5-4.0% in papermaking - after 0.5-5 ml / m biocide / e.g. Busan 25 or Busan 90 / - treated for direct use in fiberboard production to a dry matter content of 11-13%. A 12.6 ° B aluminum sulfate solution was added to the fiber suspension with constant stirring at pH 4.5-6.0 for 3 minutes. To 1 m of the treated fiber suspension, 1000 kg of gypsum and abrasive powder mixture is continuously added with vigorous stirring while the elemental fibers are dispersed in a gypsum system in a rapid mixer. The resulting fiber-gypsum suspension is poured onto an endless web.

The spheres were pressed into a 10 mm fibreboard using a continuous press belt press at 0.5-2.0 N / mm pressure and 0.1-0.05 MPa vacuum on both sides. Depending on the tape speed, plates having a thickness of 10-22 mm can be produced. After formatting and drying, the plates are sanded to the final thickness on the top side, and 35-40 g / m hydrophobic material is uniformly applied to the sanded surface. Once the abrasive powder has been removed, it is re-used to bind the gypsum to the gypsum slurry and re-used to regulate the fiber-gypsum suspension. The sheets were conditioned to 9 ± 3%, and after stacking the stack was packed in shrink wrap.

Example 2

The 3.5-4.0% fibrous slurry was treated with biocidal as in Example 1 and then pressed to a dry solids content of 35-40% using a suction filter. The press cake thus produced can be transported to the processing site, where it is diluted with returewater / circulating water / 11-13% solids from the vacuum screen press. A 12.6 ° B aluminum sulphate solution was added to the fiber suspension with constant stirring.

Adjusting the pH to 4.5-6.0, then min. After 60 s, 150 1 of a 10% solution of calcium chloride per cubic meter were added immediately prior to the addition of the fiber suspension to the mixer. 1160 kg of gypsum was added to the 3 µm of the fiber suspension thus prepared with continuous vigorous stirring to disperse the fibers in the gypsum phase. In the following, the procedure of Example 1 is followed.

Example 3

As mentioned in Example 2, a biocide treated slurry of 11-13% dry solids was prepared by mixing 2.5 kg of crystalline aluminum sulfate per cubic meter.

Gypsum is mixed with abrasive powder and 15 kg of crystalline calcium chloride per cubic meter. To 1 µm of the fiber suspension

The gypsum containing 1000 kg of additive is mixed vigorously. In the following, the procedure of Example 1 is followed.

Example 4

As described in Example 2, a biocide treated fiber suspension is prepared. To the 11-13% fiber suspension, the pH was adjusted to 4.5-6.0 with 60 kg of crystalline calcium chloride per cubic meter with constant stirring at 12.6 ° B aluminum sulphate solution and after 60 s. Calcium chloride should be added immediately before the fiber suspension and gypsum mixing begins. 840 kg of gypsum are added per 1 m of the fiber suspension and the fibers are dispersed in the gypsum phase. Sheet formation is carried out as in Example 1.

The process according to the invention has the following advantageous properties:

- the cellulose base used in the pulp sludge is used as a secondary raw material in the production of sheets, which is produced in Hungary in a volume of t / day,

- fiber sludge during production replaces waste paper which is essential for our pulp industry / e.g. Ferma.ce.ll page / and eliminates the need to use paper as a cover layer / eg. plasterboard /, eliminates the need for expensive wood and costly further processing (barking, rolling, finishing /) with a lower volume density than similar indoor applications they increase the porosity of the product and thus have a very beneficial effect on the thermal and acoustic insulation properties. The thermal conductivity of the sheets was thus v λ = 0.16 —— at a thickness of v = 10 mm. mK does not contain toxic substances that are harmful to health, such as traditional chipboard / post-release formaldehyde /, also improves building biological effects / sensation of heat, humidity control, etc. the resulting homogeneous sheet structure results in increased rolling resistance, the product can be nailed directly without damage, eliminating the need for pre-drilling,

- the 10 ram fiber board does not necessarily require the use of a circular saw, since it can be broken along the line after drawing with a sharp cutting tool of a suitable size,

- inhomogeneous, adverse properties of the wood / swelling, shrinkage, dissolution of incrusting materials, etc. / are not present in the uniform sheet structure.

The invention is not limited to the solutions described in the exemplary embodiment, but encompasses all the solutions protected by the claims, in particular the main claim.

Claims (6)

Claims CLAIMS 1. A gypsum-bonded fibreboard comprising cellulose-based fibrous sludge, characterized in that the fibreboard is 60-90 SR °, 8-15% dry matter-3 fibrous sludge and 750-1250 kg gypsum per 1 m of sludge. biocide, and preferably a gas-forming, strength-enhancing additive such as aluminum sulfate (4) and / or calcium chloride (CaCl 2). 2. A process for the production of gypsum-bonded fibreboard containing cellulose-based fibrous sludge, comprising pulping 60-90 SR ° of paper pulp in a manner known per se to a dry matter content of 8-15%, adding to the slurry a preservative and 750 to 1250 kg of gypsum per 1 m are added to the sludge slurry, and the elemental fibers of the sludge sludge are dispersed in the gypsum system with vigorous stirring, and the resulting dispersion system of W = 0.60-0.85 water gypsum is expediently spread, preferably using a continuous screen press, a vacuum of 0.1-0.05 MPa and a press pressure of 0.5-2.0 N / mm are applied to one or both surfaces of the site until hydration of the gypsum is complete. 3. A process according to claim 2, characterized in that 0.5 to 5 ml of Busan 25 or Busan 90 are added to the sludge as biocide. A process according to claim 2 or 3, characterized in that 2.0-3.0 kg of crystalline aluminum sulphate or 12.6 ° B aluminum sulphate solution is mixed per g of the sludge slurry as a gasifying, strength-enhancing additive. the pH of the suspension Set between 4.5 and 6.0. 5. Process according to any one of claims 1 to 3, characterized in that 150 l of 10% calcium chloride solution or 15 kg of crystalline calcium chloride (CaCl ₂ ) are mixed with the fibrous sludge slurry immediately before mixing with the gypsum. • · ···· -i r 6. Process according to any one of claims 1 to 3, characterized in that during pressing, sheets of 10-22 mm thickness are produced, and after pressing, the sheets are formatted, dried, sanded, 35-40 g / m hydrophobic material is applied to the sanded surface and finally the sheets air conditioning to a humidity of 6-12%.