DE10114341A1 - Milling and bleaching natural cellulosic material, giving products used for paper or cardboard manufacture or as a dietary fiber, comprises hydrogen peroxide treatment at high solids level in a hammer or centrifugal mill - Google Patents

Abstract

Milling and bleaching particles (I) of comminuted natural cellulose material using hydrogen peroxide (II) as bleaching agent, comprises that (I) are treated with (II) at a solid content of more than 60 % (preferably more than 75 %) and ground in a high-speed hammer or centrifugal mill during the bleaching. Independent claims are also included for the following: (a) bleached fibers of pine-wood with a fiber length of 50 - 150 micro m, a bulk density of 90 - 130 g/l and a degree of whiteness of 65 - 69 % ISO; (b) bleached pine-wood flour with a 32 micro m sieve residue of less than 5 %, a D50 of 15 - 20 micro m, a bulk density of 220 - 330 g/l and a degree of whiteness of 67 - 72 % ISO; (c) bleached walnut shell flour with a particle size of 300 - 800 micro m, a bulk density of 350 - 500 g/l and a degree of whiteness of 54 - 68 % ISO; (d) bleached alpha -cellulose obtained from hardwood extraction residues, with a degree of whiteness of 78 % ISO at an alpha -cellulose content of more than 90 %; and (e) bleached, partly soluble cereal fibers obtained from optionally extracted, demineralized cereal residues, rice straw or oat husks reacted with nitric, sulfuric and/or other mineral acid.

Description

The invention relates to a method of the preamble of the Proof 1 corresponding type and a number of uses of the Products manufactured using this process.

A generic method emerges from US Pat. No. 4,029,543. at In the known method, wood fibers are released in a grinder and form a fibrous pulp. This pulp is contained with a peroxide bleaching agent treated as the only bleaching agent. The mechanical The fibers are released in the presence of the used bleaching liquid from the peroxide bleaching stage.

The known method is in terms of bleach consumption and Throughput and the fineness of the bleached product improvement.

The invention is based, these improvements of the task to get to know the procedure.

This object is achieved by the invention reproduced in claim 1 solves.

It has been found that the end of the process according to the invention Gear material can be processed with high solid density, which more than 60%, according to claim 2 may even be more than 75%. The rest on 100% is water, which is partly made of the material, e.g. B. the wood itself comes partly from the sprayed-on aqueous bleach. In many In some cases, the water in the wood is already sufficient and is not required a pure addition of water. The concurrent with the bleaching process grinding constantly opens up new fracture or separating surfaces of the particles the bleach are wetted. So there is a thorough bleaching of the entire volume of the particles while reducing the required amount of bleach, which is not only economical, but also has an impact on disposal and environmental pollution. The grinding However, it must be done in a certain way that is attached to the regrind "Particles from natural cellulosic material" is adapted. These particles are neither rubbery nor as brittle as mineral material. With The effect according to the invention can be achieved in cutting mills and jet mills do not reach. For raw materials of a certain medium hardness or softness like you would expect from natural cellulosic materials z. B. wood has to be expected, rather blow and slingshot mills are considered, sitting on a rotor, at high speed all-round grinding elements such as blow bars, hammers, arms, pins or Na sen, which the feed material in flight by impact and impact, not but crushing or crushing against a surface. to Question of the mills is based on the book by Vauck and Müller "Grundoperatio nen chemical process engineering "10th edition (1994) German publisher for the basic materials industry Leipzig Stuttgart p. 324-328.  

The high solids content during grinding has the effect that the grinding we takes place considerably more intensely than, for example, in an aqueous phase. It is about an almost dry grind. The simultaneous exposure to considerable me mechanical and chemical energy on the particles provides a variety of Fractures and partitions, thus an increase in the surface and a dif base the bleach into the interior of the particles. The bleaching treatment captures the entire particle volume.

An important aspect of the invention is the subject of claim 3, according to the grinding is carried out in such a way that the particles briefly have a strong temperature be subjected to temperature increase, e.g. B. to 150 to 180 ° C (claim 4).

This temperature increase can be caused by the grinding process, but can also be supported by external means. It significantly increases the effectiveness of the bleach and thus promotes the bleaching process. By increasing the temperature, water evaporates and takes the bleach, z. B. H ₂ O ₂ concentration, on the particles.

According to claim 5, it is recommended that the bleaching grinding ei ne wind sifting is superimposed. In the case of H ₂ O ₂ , this passes through several reactive intermediate stages and breaks down on the particles, so that no problem arises with remaining amounts of H ₂ O ₂ .

The bleaching grinding takes place in a continuous process, whereby the mill is constantly fed with raw material and constantly bleached pro product is withdrawn from the mill. To avoid the meal corridor, which is accompanied by a repeated circulation of the product through the mill goes, burdened by entrained, not crushable larger particles the latter must be continuously separated from the regrind, what happens through the wind sifting.  

The grinding can advantageously be carried out according to claim 6 in a mill which draws a lot of air during the grinding process in order to drive the drying of the ground material still in the mill. In this way, bleaching, grinding and drying can be carried out in one machine and a largely dry, optionally H ₂ O ₂ -free end product is obtained.

It is advisable to heat the air supplied to the mill during the grinding process zen (claim 7), in particular with wood so high that the lignin of the wood begins to soften (claim 8). This turns one into certain If desired, fibrillation of the material occurs.

An embodiment of the invention according to claim 9 provides that Influencing the water content of the regrind within the according to claim 1 or 2 given limits of solids content formation of the end product is controlled. This results in a wetter driving style a woolier product, a drier driving style a higher percentage Fiber shortening and thus a more powdery product.

The use of hydrogen peroxide can be 0.1 to 15%, in particular 0.5 to 4 % (claim 10) and is therefore relatively low, whereby according to claim 11 the conversion of the hydrogen peroxide can be 80 to 99.99%, d. H. the amount of hydrogen peroxide comes into effect almost quantitatively.

The bleach activator consumption can be less than 0.5% (An Proverb 12).

According to claim 13, the bleaching agent can contain less than 3% or Sodium carbonate (soda) as well as other aids such as TAED or Peressig acid added.

An important aspect is the subject of claim 14, according to which the middle Residence time in the mill is only 1 to 3 minutes.  

The particles leave the mill relatively quickly, which is equivalent with a correspondingly increased throughput.

Chemical and / or enzyme treatment can be carried out before grinding of the starting material take place (claim 15), the starting material already preconditioned. This can be neutral or weakly alkaline Starting material before mixing with hydrogen peroxide and Bleach activators at 20 to 65 ° C for 3 to 90 hours with commercially available Xylanase bleaching enzymes, such as those used for kraft pulp bleaching which are implemented (claim 16).

Xylanases are special hemicellulases which contain poly in the wood saccharides of the heteroxylan type in water-soluble low molecular weight ver can break down bonds (pentose, xylose). This will be on the parti created a larger surface and the effect of the following Bleach improved.

It can be advantageous to form the particles of the starting material to compress cellulose-containing material before grinding (claim 17).

This compression can be done using a pellet press with a ring or flat die, via a granulating compactor, a briquetting system or via rollers pressure.

The raw materials used as cellulose-containing material can be very be of diverse nature. An essential example for as a starting material in Be coming cellulose-containing material is wood (claim 18), esp special bark-free spruce or fir wood (claim 19) because the it can be easily ground or fibrillated. But there are also straw (An Proverb 20), cereal shells (oats, rice, spelled), walnut shell flour (Claim 22) or annual plants (Claim 23) into consideration, the last tere according to claim 24 raw cotton, alkaline extracted raw  Cotton, ramie, sisal, jute, wheat straw, olive seed flour, coconut len flour, coconut fiber, coffee bean or cocoa extract residue and Include hard grasses.

According to claim 25, already processed celluloses can be used be, e.g. B. extracted cellulose (EFC), deinking or technical Celluloses from the paper, pulp, cardboard or hygiene article industry. Demineralized grain residues, rice, Straw and similar materials are used, such as those used in animal feed Industry as an extract residue.

As diverse as the possible starting materials of the fiction According to the process are the uses of the process products.

According to claim 28, a bark-free softwood chip (spruce, Fir), deinking fabric or technical cellulose by means of the erfindungsge Processed product as a pulp and CTMP divider serve the cardboard industry.

According to claim 29, one can use the method according to the invention Spruce wood product with 50 to 150 µm fiber length, one Bulk density of 90 to 130 g / L and whiteness of 65 to 69% ISO is used as a reinforcing fiber in papermaking. After the invent method according to the invention bleached and ground wood fibers of the fiber lengths of 50 to 150 µm or 150 to 600 µm can also be used for paper rails, on pulpers and dispersers of the cardboard industry as well as Extenders for deinking fabrics can be used.

A spruce wood flour obtained by the method according to the invention with less than 5% sieve residue to 32 µm, D ₅₀ 15 to 20 µm, bulk density 220 to 330 g / L and a whiteness of 67 to 72% ISO can be used in the manufacture of paper, Folding boxboard, other packaging, for decorative paper, paper chemicals, carbonless paper, polyurethane leather, welding electrodes, plastic films, biopolymers, PP extrudates and laminating resins.

A grain fiber obtained by the method according to the invention demineralized, with nitric acid, sulfuric acid and / or other mine cereal residues converted from ralic acids, rice straw, oat husks Product can according to claim 32 as a dietary food fiber, as Ver thicker in fiber drinks and for dietary supplement tablets be used.

The same grain fibers can be used in precoat filtration as well Drainage aids or pressing aids in the food industry be used.

According to claim 34, an α-cellulose, which according to the Invention was obtained from hardwood extraction residue in accordance with the method and a whiteness of at least 78% ISO with an α-cellulose content of over 90%, for the production of microcrystalline cellulose (MCC), especially for the pharmaceutical industry (direct tableting) and for PU Leather can be used.

According to claim 35, such an α-cellulose can also be used for the production of cellulose gels made of microcrystalline cellulose.

According to claim 36, a fine light beige walnut shell flour with 300 to 800 µm particle size and a bulk density of 350 to 500 g / L as well as a whiteness of 54 to 68% ISO advantageous for hand washing pastes as well as for rolling metal parts.

According to claim 37, a partially soluble grain fiber from demine ralisiert, with nitric acid, sulfuric acid and / or other mineral acid converted grain residues, rice straw, oat husks, which are also extra can be used for the production of MCC-based cereal fiber gels  as a synergist with xanthan, CMC and other commercially available hydrocolloids Find application.

The invention also relates to some special products made after Method of one of claims 1 to 37 were obtained.

According to claim 38, it is a reinforcing fiber for the Pa pier manufacturing, which has been obtained from spruce wood, a fiber length of 50 to 150 µm, a bulk density of 90 to 130 g / L and a Whiteness from 65 to 69% ISO.

Another such product is a microfine light beige spruce wood flour with <5% sieve residue to 32 µm, D ₅₀ 15 to 20 µm, 220 to 330 g / L bulk density and a whiteness of 67 to 72% ISO.

Claim 40 is for a fine light beige walnut shell flour with 300 to 800 µm particle size, 350 to 500 g / l bulk density and a whiteness directed from 54 to 68% ISO.

Claim 41 relates to a raw white α-cellulose from hardwood Extraction residue with a whiteness of at least 78% ISO at egg α-cellulose content of over 90%.

Claim 42 relates to a raw white partially soluble grain fiber from demi mineralized, with nitric acid, sulfuric acid and / or other mineral acid converted grain residues as well as rice straw and oat husks, the can also be extracted.

embodiment

In a production trial for the bleaching of spruce wood, a batch made of 2750 kg peroxide bleached wood fibers.  

Raw material: coarse bark-free spruce wood particles (1-5 mm), with a mixture from hydrogen peroxide (35%) and diluted TAED soda solution acts (bulk density mixture 131 g / L, moisture 22%). The amount used in the treatment solution was 3-4% techn. Hydrogen peroxide + 0.5% TAED + 0.5% sodium carbonate, each based on the solid, d. H. on the amount of dry matter wood. The treatment solution was on the Holzpar sprayed on. Contact time before grinding: a few minutes. by rate 250 kg / h The grinding was carried out on a hammer mill.

Claims (42)

1. A process for grinding and bleaching natural cellulosic material comminuted into particles with a bleaching agent such as hydrogen peroxide, characterized in that the particles of the material are mixed with the bleaching agent at a solids content of more than 60% and during the action of the bleaching agent in a can be milled with a high-speed rotating or impact mill or centrifugal mill. 2. The method according to claim 1, characterized in that the Milling is carried out at a solids content of more than 75%. 3. The method according to claim 1 or 2, characterized in that the particles briefly rise sharply in temperature due to the grinding experience hung.   4. The method according to claim 3, characterized in that the Temperature increase to 150 ° C to 180 ° C takes place. 5. The method according to any one of claims 1 to 4, characterized in net that a wind sifting is superimposed on the bleaching grinding. 6. The method according to any one of claims 1 to 5, characterized in net that the grinding takes place in a mill, which much during the grinding process Air pervades. 7. The method according to any one of claims 1 to 6, characterized in net that the air supplied to the mill during the grinding process is heated. 8. The method according to claim 7, characterized in that the Mill fed air during the grinding process is heated so high that in wood particles as the starting material the lignin begins to soften so that it fibrillation occurs. 9. The method according to any one of claims 1 to 6, characterized in net that by influencing the water content within the through the permissible solids levels given the formation of the end product is controlled. 10. The method according to any one of claims 1 to 9, characterized in net that the use of hydrogen peroxide 0.1 to 15%, especially 0.5 is up to 4.0%. 11. The method according to claim 10, characterized in that the Sales of hydrogen peroxide is 80 to 99, 99%. 12. The method according to any one of claims 1 to 11, characterized indicates that the consumption of bleach activator is less than 0.5%.   13. The method according to any one of claims 1 to 12, characterized records that the bleach less than 3% alkalis or sodium car bonat (soda) and other aids such as TAED or peracetic acid sets are. 14. The method according to any one of claims 1 to 13, characterized indicates that the average residence time in the mill is 1 to 3 minutes wearing. 15. The method according to any one of claims 1 to 14, characterized records that a chemical and / or enzyme be act of the starting material takes place. 16. The method according to claim 15, characterized in that the neutral or weakly alkaline starting material before mixing Hydrogen peroxide and bleach activators at 20 to 65 ° C over three to ninety hours with commercial xylanase bleaching enzymes as for Kraft pulp bleaching is used. 17. The method according to any one of claims 1 to 16, characterized records that the particles of cellulose containing material must be compacted before grinding. 18. The method according to any one of claims 1 to 17, characterized shows that wood is used as the cellulose-containing raw material. 19. The method according to claim 18, characterized in that the Wood is bark-free spruce or fir wood. 20. The method according to any one of claims 1 to 17, characterized records that the cellulose-containing material is straw.   21. The method according to any one of claims 1 to 17, characterized records that the cellulose-containing material is cereal husks (oats, rice, Spelled). 22. The method according to any one of claims 1 to 17, characterized records that the cellulose-containing material is walnut shell flour. 23. The method according to any one of claims 1 to 17, characterized records that the cellulosic material is annual plants. 24. The method according to claim 23, characterized in that the Annual plants raw cotton, alkaline extracted raw cotton, Ramie, Sisal, Jute, Wheat Straw, Olive Kernel Flour, Coconut Shell Flour, Ko carbon fiber, coffee bean or cocoa extract residue or hard grass believe it. 25. The method according to any one of claims 1 to 17, characterized records that cellulose products are used as the cellulose-containing material become. 26. The method according to claim 25, characterized in that as cellulose-containing material extracted cellulose (EFC), deinking or technical celluloses made from paper, cellulose, cardboard or hygiene products kel industry can be used. 27. The method according to any one of claims 1 to 17, characterized records that as a cellulosic material, acid demineralized cereals leftovers, rice straw and the like are used in the feed Industry as an extract residue. 28. Use of a method according to one of claims 1 to 27 from bark-free softwood chips (spruce, fir), deinking or technical  Cellulose-derived product as wood pulp and CTMP Partial replacement for the cardboard packaging industry. 29. Use of a method according to one of claims 1 to 27 product made from spruce wood with a fiber length of 50 to 150 µm, one Bulk density of 90 to 130 g / L and whiteness of 65 to 69% ISO as a reinforcing fiber for the paper industry. 30. Use of a method according to one of claims 1 to 27 obtained product with a fiber length of 50 to 150 µm or 150 up to 600 µm for paper production and on pulpers and dispersers of the carton gnawing industry and as an extender for deinking fabrics. 31. Use of according to the method of one of claims 1 to 27 Spruce flour obtained with <5% sieve residue on 32 µm, D50 15 up to 20 µm, 220 to 320 g / L bulk density and a whiteness of 67 to 72 % ISO in the production of paper, folding boxboard, other ver packing carton, decorative paper, paper chemicals, carbonless papers, Polyurethane leather, welding electrodes, plastic foils, biopolymers, PP Extrudates and laminating resins. 32. Use of according to the method of one of claims 1 to 27 from straw, oat husks, spelled husks, rice husks, psyllium Seeds, soybean-derived grain and vegetable fibers, which me mechanically cleaned, washed and stripped of starch as diets table food fiber, as a thickener in fiber drinks as well as for Nah approximately supplements tablets. 33. Use of the method according to one of claims 1 up to 27 from straw, oat husks, spelled husks, rice husks, psylli around seeds, soy fibers obtained grain fibers, which are mechanically ge cleaned, washed and de-starched or demineralized,  with nitric acid, sulfuric acid and / or other mineral acids implemented grain residues, rice straw, oat husks, which are also extracted can be in precoat filtration and as a drainage aid and pressing aids in the food industry. 34. Use of α-cellulose, which is one of the Claims 1 to 27 was obtained from hardwood extraction residue and a whiteness of at least 78% ISO with an α-cellulose content above 90%, for the production of microcrystalline cellulose (MCC) for the pharmaceutical industry (direct tableting) and for PU leather. 35. Use of α-cellulose, which is one of the Claims 1 to 27 was obtained from hardwood extraction residue and a whiteness of at least 78% ISO with an α-cellulose content above 90%, for the production of cellulose gels from microcrystalline Cellulose. 36. Use of walnut shell flours made according to the procedure one of claims 1 to 27 from walnut shell flour with 300 to 800 microns Particle size, a bulk density of 350 to 500 g / L and a whiteness from 54 to 68 ISO for hand washing pastes and for rolling me metal pieces. 37. Use of a partially soluble grain fiber, which after Method of one of claims 1 to 27 from demineralized, with saltpetre acid, sulfuric acid and / or other mineral acids reacted crop deresten, rice straw or oat husks, which can also be extracted for the production of grain fiber gels based on MCC as a synergist Xanthan, CMC and other commercially available hydrocolloids.   38. bleached spruce fiber with a fiber length of 50 to 150 µm, a bulk density of 90 to 130 g / L and a whiteness of 65 up to 69% ISO. 39. Bleached spruce wood flour with a sieve residue of 32 µm from less than 5%, a D50 of 15 to 20 µm, a bulk density of 220 up to 330 g / L and a whiteness of 67 to 72% ISO. 40. Bleached walnut shell flour with a particle size of 300 to 800 µm, a bulk density of 350 to 500 g / L and a whiteness of 54 to 68% ISO. 41. Bleached α-cellulose from hardwood extraction residue with one Whiteness of at least 78% ISO with an α-cellulose content of over 90%. 42. Bleached, partially soluble grain fiber from demineralized, with Implemented nitric acid, sulfuric acid and / or other mineral acids Grain residues, rice straw or oat husks, which can also be extracted NEN.