WO2006027137A1

WO2006027137A1 - Flat fibrous material and method for production thereof

Info

Publication number: WO2006027137A1
Application number: PCT/EP2005/009290
Authority: WO
Inventors: Wolfgang Christ; Hans Joachim Knapp; Klaus Schmalfuss
Original assignee: Wolfgang Christ; Hans Joachim Knapp; Klaus Schmalfuss
Priority date: 2004-09-03
Filing date: 2005-08-29
Publication date: 2006-03-16
Also published as: DE102004043219A1

Abstract

The invention relates to a flat material such as paper, paperboard and cardboard comprising a cellulose-containing fibrous material in the form of intermediate stuff and auxiliary agents, wherein said intermediate stuff is obtainable by impregnating in a saturated aqueous borax solution and subsequent drying.

Description

Flat fibrous material and process for its production

The invention relates to a sheet material of a cellulose-containing pulp as Halb¬ material, in particular papers, paperboard or cardboard, wherein the pulp has been pretreated by borax and a process for its preparation.

Sheet-like materials consisting of a fibrous material, such as papers, cardboard or paperboard, consist essentially of a pulp as pulp and of paper auxiliaries. Pulp, pulp and / or waste paper are used as pulp in the pulp. To produce this sheet material, a fiber felt is first formed from the fibrous pulp by dewatering the pulp suspension on a sieve. The resulting fiber felt is then subsequently compressed and dried. The weight per unit area is generally mine up to 225 g / m ² . At basis weights> 225 g / m ² one speaks of cardboard. The term cardboard with basis weights of 150 to 600 g / m ² encompasses both paper and paperboard types.

Cellulosic materials of this type are used in many forms as office material but also in construction. In particular, in the construction industry, there is a requirement that used materials flame retardant or flame retardant properties have. These requirements are currently met only partially or in part. However, there is great interest in using cellulosic substances, e.g. as insulating and insulating material, since recycling materials can be used as starting material and good insulation properties can be proven.

Numerous attempts are known in the literature to make cellulose-containing materials at least flame-retardant by impregnation or coating.

Additives such as ammonium sulfate as a flame-retardant Mate¬ rial are now no longer allowed because under heat toxic additives are released and there is a corrosive effect of the acidic by-products on electrical lines.

The use of boron compounds is unobjectionable. For example, DE 195 16 186 describes an insulating material with properties of fire class B1, in which cellulose-containing starting materials include borax pentahydrate, borax decahydrate, boraxpolyboron and / or boric acid. The dry fibers are impregnated by spraying an aqueous solution of borax and then added with other binders. The efficiency of the use of relatively expensive additives can be increased if, as described in US Pat. No. 4,370,249, talcum is added in addition to the boron compound. Talc does not support combustion. The loss of weight on heating corresponds to the loss of water of the talc, which supports the flame retardant effect of borax. In addition, the hydrophobic properties of the cellulose-containing material are improved.

Generally, an addition of powdered boric acid

(H ₃ BO ₃ ) and pulverized borax (Na ₂ B ₄ O ₇ 5H ₂ O) sodium terapatate pentahydrate, mixed in the ratio 1: 2 to 1: 4, in the relevant industry as the best, but expensive means for flame retardancy of cellulose products (see US Pat. No. 6,025,027). As further disadvantages of these solid substances, which are added to the dry fibers, the abrasion in the corresponding mills and corresponding safety requirements for the dust are considered.

In US Pat. No. 6,025,027 it is also attempted to supply the additives in liquid form to the process. For this purpose, borax is treated with alkali hydroxide to produce a metaborate. The metaborate is sprayed onto the fibers. Subsequently, the metaborate is treated by spraying an acid to neutralize the alkaline material.

Na ₂ B ₄ O ₇ - H ₂ O + 2Na (OH) + 2H ₂ O → 2Na ₂ O. B ₂ O ₃ . 4H ₂ O

Na ₂ O B ₂ O ₃ . 4H ₂ O + H ₂ SO ₄ → 2H ₃ BO ₃ + Na ₂ SO ₄ . 2H ₂ O + H ₂

A complete process (spraying on cellulose and then drying by hot air) to produce Position of cellulose-containing webs describes the US 5,534,301. In order to avoid powdery additives having the abovementioned disadvantages, additions of a mixture of ammonium sulfate, monoammonium phosphate, diammonium phosphate, boric acid, aluminum sulphate, sodium tetraborate, iron sulphate and zinc sulphate in liquid form are proposed, which have already been used in earlier steps have been described.

Et al can be related to a document US 2,386,471 or AT 13783 Herz, in which an aqueous fire-solid solution consisting of borax, ammonium phosphate and ammonium chloride for the impregnation of various materials ner is proposed.

From the state of the art, however, hitherto no sheet-like materials, in particular paper, cardboard or board materials have been known which have a high flame-retardant effect, in particular materials which fulfill the requirements of the fire class B1-A2 DIN4102. It is therefore the object of the present invention to indicate corresponding flat materials which fulfill the conditions according to the abovementioned fire class and to specify a method for producing these materials.

The object is achieved with respect to the sheet-like materials by the features of patent claim 1 and with respect to the method of manufacture by the features of claim 6. The dependent claims show advantageous developments.

According to the invention, it is thus proposed that the cellulose-containing pulp be produced as a pulp, as an essential component of the sheet-like materials, by a special pretreatment process. is presented. According to the invention, the pulp is obtained by impregnating the pulp in a saturated aqueous borax solution and then drying, and then mixing the pulp thus produced with borax. An essential element is that an aqueous borax solution is added to the pulp, in which the saturation limit has been increased by addition of, for example, monoammonium phosphate to the extent that the pulp can be fed with up to five times the amount of borax associates. The reactive materials thus produced explain the high fire resistance of the end product. The pulp produced in this way is then used in processes known per se for the production of the sheet-like materials.

It has now surprisingly been found that a paper, board or cardboard material which has been produced with such a pulp, fulfills the conditions according to the fire class B1-A2 DIN4102.

As the Applicant could show, the specific pretreatment achieved is that the adsorption of the borax molecules takes place not only physically, ie by incorporation of borax molecules between the macro-fibrils, but also chemically by binding to the accessible hydroxyl groups of the glucose molecules the amorphous areas of the microfibrils. The borax molecules thus form a monomolecular layer that envelops the fibers. Only then do deposits form between the macrofibrils. It is a peculiarity that the chemical bonding forces are significantly stronger than the physical binding forces. The envelope of the microfibrils is therefore particularly intensive and effective in protecting the fiber. sam. The prerequisite for entering into chemical bonds of the borax with the hydroxyl groups of the cellulase is now a relative lack of free water molecules, since water preferably forms hydrogen bonds to the glucose molecules. The situation can best be described by a competition of bonds with the free hydroxyl groups of the glucose molecules. By increasing the saturation limit of the borax solution according to the invention, targeted chemical compounds of the borax are promoted with the glucose molecules. With this mechanism of action there is a quantitative difference from the known methods of treating cellulose with borax. When sprayed with aqueous borax solution, where the concentration of borax is within the solubility limit of borax in pure water, even if it contains ammonium phosphate, the fibers are merely wetted with water. After drying, the borax crystallizes out and adheres physically to the fiber surface. If the borax is fed in solid form, a similar result is achieved, and the crystals adhere to the macrofibrils. In these two cases, the borax is physically adsorbed.

The chemical adsorption of the borax into the facial fibrils of the cellulose obviously achieves the outstanding properties of the material according to the invention. The increase in the saturation limit of borax in aqueous solution can be increased by various additives. It has been shown that the saturation limit can be increased to such an extent by the addition of monoammonium phosphate that ultimately a contribution of borax with more than 20% solids content in the paperboard and paper masses is achieved, as a result of which the extremely good high firing range is achieved. durability is realized.

From a material point of view, the invention in the material according to the invention comprises all fibrous cellulose-containing pulps which are known per se from the prior art. Usually, pulps, pulps and / or waste paper are used as starting materials here.

Of course, the material according to the invention may also contain paper auxiliaries, such as fillers, dyes, binders, optical brighteners, retention agents and / or deinking chemicals, as is known per se from the prior art. In the case of the dyes, those which are suitable for dyeing the compositions or for surface dyeing in coating compositions are suitable. Suitable binders are starch, casein and other proteins, plastic dispersions or resin glues. Ophthalmologists are those who usually increase the degree of wisdom. Retention agents are aluminum sulfate, synthetic and cationic substances. The mentioned deinking chemicals die¬ nen for the treatment of waste paper, various other substances such. Wetting agents, defoamers, preservatives, etc. can furthermore be added.

The invention further relates to a method for producing the above-described sheet-like material.

According to the invention, a conventional process for the production of paper, paperboard and cardboard is used. Such materials are usually formed by dewatering a pulp suspension of the pulp on a sieve. The resulting fiber felt is then compressed and dried. According to the invention, it is now proposed that the pulp used be immersed in an aqueous saturated borax solution. As borax solution, a solution of borax decahydrate is preferably used. Advantageously, the procedure is such that the saturated borax solution is initially brought into contact with the dry fibers. To improve the absorption process of the saturated aqueous borax solution into the fibers, this is followed by at least 20 minutes of grinding, kneading and / or mixing, preferably in a powder. In the pulper, the mass is kept in constant motion.

It is also advantageous if subsequently a reduction of the consistency in several stages from 18% solids to less than 0.4% is made. The drying of the fibrous pulp preferably takes place in stack or belt driers in several different temperature stages. Best results in the formation of the crystal lattice are achieved when working with three drying stages in the range of 115 to 145 ⁰ C, preferably with the temperature sequence 125 ⁰ C, 138.5 ⁰ C and 123 ⁰ C. It is important to ensure that the temperature never rises above 142 ⁰ C. This results in an undesirable bubble formation. It has further proved to be advantageous if the thus pretreated getrock- designated fibrous pulp then, preferably still mehr¬ days storage a three-day Lage¬ tion in air at approximately 10 to 35 ⁰ C is subjected.

Claims

claims

1. Flat, flame-retardant material from a cellulose-containing pulp as a pulp, and auxiliaries, characterized gekenn¬ characterized in that the cellulosic fibrous pulp has been obtained by impregnation in a saturated aqueous borax solution and subsequent Trock¬ tion, wherein the borax che¬ is mixed via the free hydroxyl groups of Cellu¬ loose.

2. Sheet material according to claim 1, characterized ge indicates that the Boraxmoleküle form a monomolecular layer enveloping the fibers.

3. Sheet material according to claim 1 or 2, da¬ characterized in that the cellulose containing fibrous pulp pulp, pulp and / or waste paper is.

4. Sheet material according to at least one of claims 1 to 3, characterized in that the aids are selected from fillers, dyes, binders, optical brighteners,

Retention aids and / or deinking chemicals.

5. Sheet material according to at least one of claims 1 to 4, characterized in that it is paper, cardboard or cardboard.

6. A process for producing a sheet-like material according to at least one of claims 1 to 5 by dewatering a Faserstoffauf¬ leaching of the pulp on a wire and subsequent compression and drying of Fa¬ serfilzes, characterized in that a pulp is used by Impregnation of the pulp in a saturated borax solution whose saturation limit is increased by the addition of monoammonium phosphate, and subsequent drying and mixing of the thus prepared pulp with solid borax has been obtained.

7. The method according to claim 6, characterized marked that borax decahydrate is used for the borax solution.

8. The method according to claim 6 or 7, characterized ge indicates that, following the impregnation of the pulp, a grinding, kneading and / or mixing operation is performed.

9. The method according to at least one of claims 6 to 8, characterized in that the Trock¬ tion of the pulp in floor or Bandtrock¬ nern follows with different temperature levels.

10. The method according to claim 9, characterized gekennzeich¬ net, that three drying stages with Temperaturfol¬ conditions between 115 and 135 ⁰ C are performed.

11. The method according to claim 10, characterized gekennzeich¬ net, that a multi-day storage, preferably three days at least 10 to 35 ⁰ C an¬ closes.