DE102006061480A1 - Producing fibrous material comprises producing a chemical solution, mixing the chemical solution with wood and/or annual plant; heating the chemical solution and pulping and then separating the woods and the chemical solution - Google Patents

Abstract

Producing fibrous material from wood or annual plants with a lignin content of at least 15% for soft wood and 10% for annual plants comprises: producing a chemical solution; mixing the chemical solution with wood and/or annual plant; heating the chemical solution and the woods and/or the annual plants and subsequently either removing free-flowing chemical solution and pulping the woods and/or the annual plants in the vapor phase or pulping the woods and/or the annual plants in liquid phase and separating the free-flowing chemical solution and the woods and/or the annual plants. Producing fibrous material from wood or annual plants with a lignin content of at least 15% for soft wood, of at least 12% for hard wood and of at least 10% for annual plants, related to the oven dried fiber mass, comprises producing a chemical solution with more than 5% of chemicals (calculated as sodium hydroxide) for soft wood or with more than 3.5% of chemicals (calculated as sodium hydroxide) for hard wood or with more than 2.5% of chemicals (calculated as sodium hydroxide) for annual plants; mixing the chemical solution with wood and/or annual plant in a given liquor ratio; heating the chemical solution and the woods and/or the annual plants at a temperature that is above the room temperature and subsequently either removing free-flowing chemical solution and pulping the woods and/or the annual plants in the vapor phase or pulping the woods and/or the annual plants in liquid phase and separating the free-flowing chemical solution and the woods and/or the annual plants.

Description

The The invention relates to a process for producing pulp Wood or annual plants with a lignin content for conifers of more than 15%, for hardwoods of more than 12% and for Annual plants of more than 10%, in each case based on the produced otro pulp, wherein the pulp predetermined strength properties having.

It For example, processes are known which produce relatively high levels of fiber Lignin content of more than 15% for softwood and from about 12% for Produce hardwood. They provide a yield of 70% or more on the starting material used. These methods are based on chemical and / or mechanical decomposition of wood.

at Mechanical defibration of the wood is this - usually after a pre-damping - in grinding units in fiber bundles disassembled. These fiber bundles are then defibrillated by further grinding into individual fibers. The yield is very high, but also the required grinding energy. The strength of the wood fibers is - even after grinding - very low, because the fibers contain much native lignin and therefore little binding potential exhibit. They are also strong due to the mechanical defibration degraded what their recyclability impaired.

In the case of chemical decomposition of the wood, chemicals usually act on the wood under increased pressure and elevated temperature. A typical process for high yield pulps is the NSSC process. But other processes, such as Kraft or soda, can also be modified to produce high yield pulps (see "Choosing the best brightening process", N. Liebergott and T. Joachimides, Pulp & Paper Canada, Vo. 80, No. 12, December 1979 ). If the extraction of the originally used wood is to be limited to a maximum of 30%, far fewer chemicals are needed and used than in the production of pulps that are to be completely lignin-free. For the production of high-yield pulps, the amount of chemicals is metered depending on the desired yield. In order to achieve a yield of about 70% based on otro wood use, it is recommended in the prior art to use up to 10% of chemicals based on the starting material. In the case of solid pulps, the use of chemicals is often 30% of the chemicals related to the otro wood or more.

chemicals determine the process costs, so they are possible used sparingly. CTMP pulps are usually made with chemical quantities made from 3% to 5%. In known, industrially established Process for the preparation of high yield pulps, e.g. B. the NSSC process, up to 10% chemicals are based on the starting material used. With such a limited use of chemicals is still no recovery for the recovery the chemicals installed. Despite the relatively small amounts of chemicals leads this Type of pulp production to a considerable environmental, especially water pollution, not only because of the entry of chemicals but mainly because of the organic Freight being dumped in the receiving waters.

to Cost situation is to be noted, that with mechanically manufactured Fibers the sharply rising energy prices the manufacturing costs strain. For chemically produced high yield pulps the production with the costs for burdened the lost chemicals.

High yield pulps are ground to high levels of grinding for current uses. Only then will they reach an acceptable level of strength. As high degrees of grinding here are values of about 300 ml CSF (Canadian Standard Freeness), to be equated with 41 ° SR (Schopper-Riegler, see below) and 500 ml of CSF, to be equated with 26 ° SR, to see how they z. In "Choosing the best brightening process", N. Liebergott and T. Joachimides, Pulp & Paper Canada, Vo. 80, No. 12, December 1979 , are described for high yield pulp from softwood. A high degree of grinding is achieved by using mechanical energy. The fibers are rubbed against each other or on a grinder or on a grinding media and thus changed in their surface properties towards a better bonding behavior. The high degree of grinding is therefore not an end in itself. It results rather from the requirements of the strength properties of the fiber.

The In particular, high yield fibers produced by mechanical and / or chemical means become used where not necessarily a high Endweißgrad and high whiteness stability required are. You could there are many other fields of application, if the strength level could be increased.

It It is therefore an object of the invention to provide a process for the preparation of Pulp with a lignin content of more than 15% for softwood, more than 12% for Hardwood and more than 10% for To propose annual plants, in an economic way Fibers high strength can be produced.

• – Herstellen einer Chemikalienlösung mit mehr als 5% Chemikalien (berechnet als NaOH) für Nadelholz oder mit mehr als 3,5% Chemikalien (berechnet als NaOH) für Laubholz oder mit mehr als 2,5% Chemikalien (berechnet als NaOH), jeweils bezogen auf die otro Menge des eingesetzten Holzes,
• – Mischen der Chemikalienlösung mit dem Holz bzw. Einjahrespflanzen in einem vorgegebenen Flottenverhältnis,
• – Erwärmen der Chemikalienlösung und des Holzes bzw. Einjahrespflanzen auf eine Temperatur über Raumtemperatur und anschließend entweder (1. Alternative)
• – Entfernen frei fließender Chemikalienlösung und
• – Aufschließen des Holzes bzw. Einjahrespflanzen in der Dampfphase oder (2. Alternative)
• Aufschließen des Holzes bzw. Einjahrespflanzen in Gegenwart der Chemikalienlösung in flüssiger Phase und
• – Separieren der frei fließenden Chemikalienlösung und des Holzes bzw. der Einjahrespflanzen.

This object is achieved with a method for the production of pulp from wood or annual plants with a lignin content of at least 15% for softwood and 12% for hardwood and 10% for annual plants, each based on the otro fiber mass, with the steps:

• - Make a chemical solution with more than 5% chemicals (calculated as NaOH) for softwood or with more than 3.5% chemicals (calculated as NaOH) for hardwood or with more than 2.5% chemicals (calculated as NaOH), each purchased on the otro amount of wood used,
• Mixing the chemical solution with the wood or annual plants in a predetermined liquor ratio,
• - Heating the chemical solution and the wood or annual plants to a temperature above room temperature and then either (1st alternative)
• - Remove free-flowing chemical solution and
• - digesting the wood or annual plants in the vapor phase or (2nd alternative)
• Digesting the wood or annual plants in the presence of the liquid phase chemical solution and
• - Separating the free-flowing chemical solution and the wood or annual plants.

The inventive method based on that for the production of high yield pulps higher Chemical quantities are used as usual. More than 5% chemicals lie for softwood clearly over the usual Chemical quantities for technical pulp production, also more than 3.5% chemicals for hardwood and 2.5% for Annual plants. This high use of chemicals yields fibrous materials with good yield and excellent strength properties. So be for Softwood at grinding grades from only 12 ° SR to 15 ° SR, breaking lengths of more than 8 km, but also tear lengths of measured more than 9 km and more than 10 km. For hardwoods at only 20 ° SR values of more than 5 km, but also more than 6 km and measured more than 7 km. This will be the desired high level of strength reached.

It is more extraordinary Advantage of the method according to the invention to see that these strength values already at extremely low Grind grades are achieved, as previously for high-yield fibers not available were. Fibers according to the prior art show at Mahlgrade from 12 ° SR to 15 ° SR for softwood pulps or from 20 ° SR for hardwood an unacceptable level of strength. Known pulps have at these low degrees of grinding so far result in fibers that no sufficient binding capacity have the corresponding and no sufficient strength properties for an economic Have offered to use such fibers.

When Annual plants are particularly suitable for bamboo, hemp, rice straw, Bagasse, wheat, miscanthus or similar

By contrast, the fibrous materials produced by the process of the invention have tear lengths of more than 8 km up to 11 km and tear strengths of more than 70 cN up to more than 110 cN, even at grinding degrees in the range of 12 ° SR to 15 ° SR, based on a Leaf weight of 100 g / m ² . These low freeness levels are also achieved with a low specific demand for grinding energy, which is less than 500 kWh / t pulp for softwood pulps, and for hardwood pulp the demand for grinding energy may even be less than 300 kWh / t pulp. The realization that the high level of strength is achieved even at low grinding degrees of 12 ° SR to 15 ° SR for softwood and 20 ° SR for hardwood and below, is an integral part of the invention.

These high strength values are for Fibers with a lignin content of more than 15% for softwood pulps, of more than 12% for Hardwood pulp or more than 10% for annual plants so far not known. The high strength level can also be used for fibrous materials with an even higher one Lignin content can be maintained. The inventive method is also suitable for the production of softwood pulps with a lignin content of more than 18%, preferably more than 21%, advantageous of more than 24% in terms of otro fiber mass. Hardwood fibers with a lignin content of more than 14%, preferably more than 16%, more preferably more than 18% and annual plants with a Lignin content of more than 10%, preferably more than 12%, in particular more than 19% can also with the method according to the invention produced and show a high level of strength.

The Composition of the chemical solution used for digestion can in agreement with the wood to be grown or the annual plants and the desired ones Fiber properties are set. Usually will be alone used a sulfite component. Alternatively or in addition can a sulfide component come on. A digestion with a sulfite component is through the presence of sulfide components is not disturbed. Technically, mostly sodium sulfite but also the use of ammonium or potassium sulfite or of magnesium bisulfite is possible. In particular, when high amounts of sulfite can be used to dispense with the use of an alkaline component, because even without the addition of alkaline components, a high pH adjusts the digestion.

to PH adjustment and delignification support For example, an acidic and / or an alkaline component can be added. The alkaline component is usually sodium hydroxide (NaOH) used. Possible but is also the use of carbonates, especially sodium carbonate. All Information on chemical quantities of the digestion process in this Document, e.g. B. for the total use of chemicals or for the division the sulfite component and the alkaline component are, as far as not stated otherwise, each calculated and reported as sodium hydroxide (NaOH).

As an acidic component, acids can be added in order to set the desired pH. However, preference is given to the addition of SO ₂ , if appropriate in aqueous solution. It is inexpensive and readily available, especially if the spent chemical solution z. B. based on sodium sulfite, after digestion is prepared for further use.

It is considered independent inventive performance, the advantages of using a Quinone component for recognized the high yield digestion according to the invention to have. Chinon components, especially anthraquinone, be so far in the production of pulps with minimal lignin content used at the end of the digestion an undesirable To prevent attack on the carbohydrates. By adding quinone components will it be possible the digestion of wood until almost complete degradation of lignin. It has turned out to be an unprecedented, unexpected property of Chinon components proved that these are the speed lignin degradation in the production of high yield pulps increase significantly. The duration of the digestion can z. B. in the production of softwood pulps by more as half, be shortened by more than three quarters depending on digestion conditions. This remarkable effect comes with minimal use of quinone reached. Optimal is a use of z. As anthraquinone, the between 0.005% and 0.5%. Use of anthraquinone of up to 1% also provides the desired effect. A use of more than 3% anthraquinone is usually uneconomical.

Out one or more of the aforementioned chemicals, a chemical solution is prepared. Most of time becomes an aqueous solution stated. As an option, the use or the addition of organic solvents be provided. Alcohol, especially methanol and ethanol in combination with water, particularly effective chemical solutions for the production high quality high yield fiber. The mixing ratio of Water and alcohol can for the respective raw material can be optimized in few attempts.

The for producing a pulp with a yield of at least 70% to be used according to the invention Amount of chemicals at least 5% for Softwood, at least 3.5% for Hardwood and at least 2.5% for Annual plants, in each case based on the otro to be broken down Wood or annual plant mass. The quality of the produced pulp shows the best results with a chemical use of up to to 15% for Softwood up to 10% for Hardwood and up to 10% in annual plants. To be favoured between 9% and 11% of chemicals based on the otro used Wood in softwood, added. For hardwoods the use of chemicals is rather lower, preferably between 4% and 10%, more preferably between 6% and 8%, and annual plants between 3 and 10%.

As already explained above, setting a specific pH is by no means required. Only if z. B. special properties of the pulps (especially high whiteness, a certain ratio of breaking lengths and tear resistance) to be achieved with the digestion, it may be useful to add acid or an alkaline component before or during the digestion. According to an advantageous embodiment of the method according to the invention, regardless of the chosen use of chemicals as a whole, a ratio between an alkaline component and sulfur dioxide (SO ₂ ) can be adjusted within a wide range. SO ₂ is mentioned here as representative of the above-mentioned acidic component. So it can be used instead of SO ₂ and an acid. Since the possibly added quinone component is used only in minimal quantities, usually well below 1%, it is for the setting the This ratio is negligible. A ratio of alkaline component: SO ₂ in a range of 4: 1 to 1.6: 1 is well suited to carry out the process according to the invention and to achieve fibers with high strength properties. A common, particularly suitable range is between 2: 1 and 1.6: 1. The adjustment of the proportionate components is dependent on the aufzuschließenden raw material and the respective selected process control (digestion temperature, digestion time, impregnation).

The inventive method can be carried out in a wide pH range. The ratio of alkaline component to acidic component or the use of a acid or an alkaline component can be adjusted that at the beginning of the process, a pH between 6 and 11, preferably set between 7 and 11, more preferably between 7.5 and 10 becomes. The more alkaline pH values between 8 and 11, which for the inventive method are beneficial, favor also the effect of the quinone component. The inventive method is tolerant of pH; there are few chemicals for pH adjustment required. This has a favorable effect the price for Chemicals off.

Without further addition of acid or alkaline component arises, for. B. for softwood, at the end of the digestion a pH between 8 and 10, usually between 8.5 and 9.5 in the free flowing chemical solution as well as the dissolved ones organic components liquefied by the digestion. To the solved ones include organic ingredients especially lignosulfonates.

The Liquor ratio, so the relationship the amount of otro wood or annual plants to the chemical solution, is between 1: 1.5 and 1: 6. Preference is given to a liquor ratio of 1: 3 to 1: 5. In this area is a good and easy mix and impregnation of the to be closed Materials guaranteed. For softwood becomes a liquor ratio of 1: 4 preferred. For Wood chips with a large surface can the fleet ratio also much higher lie to allow rapid wetting and impregnation. At the same time, the concentration of the chemical solution can be so be kept high that the circulating liquid quantities are not too large.

The Mixture or impregnation the wood or year-old digestion material is preferably carried out at elevated temperatures. Heating up the wood chips and the chemical solution up to 110 ° C, preferably up to 120 ° C, particularly preferably up to 130 ° C leads to a fast and uniform digestion of the wood. For mixing or impregnating the wood chips is a period of up to 30 minutes, preferably up to 60 minutes, more preferably up to 90 minutes advantageous. The optimal time depends on the quantity the chemicals and the liquor ratio and the type of digestion (liquid or vapor phase).

Of the Digestion of the mixed or impregnated with the chemical solution Lignocellulosic material is preferably carried out at temperatures between 120 ° C and 190 ° C, preferably between 150 ° C and 180 ° C. For the most woods Digestion temperatures between 155 ° C and 170 ° C are set. Higher or higher lower temperatures can be set, but in this temperature range are the energy expenditure for the Heating and accelerating the digestion in an economic relationship to each other. higher Temperatures can also negative for the strength and whiteness of the Impact fibers. The generated by the high temperatures Pressure can easily by appropriate design of the digester be caught. Usually is the duration of heating only a few minutes, usually up to 30 minutes, advantageously up to 10 minutes, especially when using steam is heated. The duration of the heating up can be up to 90 minutes, preferably take up to 60 minutes, z. B. when in the liquid phase is disrupted and the chemical solution along with the wood chips too is heating.

The Duration of digestion will depend mainly on the desired Fiber properties selected. The duration of the digestion can be shortened to up to 2 minutes, z. For example the case of a vapor phase digestion of a hardwood with low Lignin content. It can also be up to 180 minutes, though z. B. the digestion temperature low and the natural lignin content of the to be closed Wood is high. Even if the initial pH of the digestion In the neutral range, a long digestion time may be required be. Preferred is the digestion time up to 90 minutes, especially in coniferous wood. Particularly preferred is the digestion time up to 60 minutes, advantageously up to 30 minutes. A digestion time of up to 60 minutes occurs mainly in deciduous trees in Consideration.

In annual plants, the digestion time is up to 90 minutes. The use of a quinone component, in particular anthraquinone, allows a reduction of the digestion time up to 25% of the Time required without the addition of anthraquinone. If the use of quinone components is omitted, the digestion time is extended by more than one hour, for example from 45 minutes to 180 minutes, for comparable digestion results.

To an advantageous embodiment the method according to the invention the duration of the digestion is set as a function of the selected liquor ratio. The lower the liquor ratio, the shorter the process duration can be set.

The Production of high yield pulp with high chemical use of more than 5% for Softwood, of more than 3,5% for Hardwood and at least 2.5% for Annual plants appear first uneconomical. But tests have shown that only a part the chemicals during the partial digestion of the lignocellulosic material consumed becomes. The predominant Part of the chemicals is discharged unused, either before the digestion (vapor phase digestion) or after digestion (digestion in the liquid phase). The actual Consumption of chemicals is below those used in the digestion solution Amounts.

Of the Chemical consumption is recorded as the amount of chemicals - related on the original amount of chemicals used - after removal or separation the chemical solution and, if necessary, the detection of chemical solution after defibering or measured in conjunction with a detection of the chemical solution becomes. The consumption of chemicals depends on the absolute amount the for the chemicals used, based on the otro to be broken down Carpentry and joinery. The higher the Use of digestion chemicals is the lower the direct Sales of chemicals. When used with 27.5% chemicals on otro wood mass, for example, only about 30% of the used Consumed chemicals. When used with 15% chemicals on otro wood, however, 60% of the chemicals used are consumed, as could be proven in laboratory experiments. The consumption of chemicals for the inventive method is according to a preferred embodiment of the procedure during digestion up to 80%, preferably up to 60%, more preferably up to 40%, advantageously up to 20%, particularly advantageous up to 10% of the chemical used at the beginning of the digestion becomes.

Of the Chemical consumption for producing a ton of pulp lies at about 6% to 14% sulphite and / or sulphide component and, if applicable, alkaline and / or acidic component and optionally quinone component based on otro pulp (deciduous and coniferous or annual plants). According to the invention this is sufficient Quantity of chemicals to a pulp with the given characteristics manufacture. However, to a uniform process result guarantee and possibly special, desired To get pulp properties, it may be useful prove, higher Chemical quantities for to use the digestion, z. As the above-mentioned up to 30% chemicals based on otro wood or annual plant mass.

Of the Use of these chemicals at the beginning of the digestion shows advantageous effect, since the fibers obtained in this way previously unavailable Properties, in particular high strength properties and high whiteness exhibit. In particular, no digestion method is currently available that has a broad pH range from neutral to alkaline Produced fibers with high strengths. As economically special It has been found attractive that the inventively prepared Fibers with much lower energy consumption to specified Grinding degrees to grind are known as fibrous materials. In addition, develop the high strengths already at unusually low degrees of grinding from 12 ° SR up to 15 ° SR for softwood and from 20 ° SR for hardwood.

Excess chemicals are present after mixing and impregnating the wood with the chemical solution or after digestion in the free flowing liquid. This excess is deducted before digestion (1st alternative) or after digestion (2nd alternative). According to an advantageous embodiment of the method, the composition of the removed chemical solution is detected and then adjusted to a predetermined composition for re-use for the production of fibers. The chemical solution that is removed before or after the decomposition of the wood or annual plants no longer has the original composition. At least some of the chemicals used for digestion have - as described above - penetrated into the material to be digested and / or has been consumed in the digestion. The unused chemicals can easily be used again for the next digestion. However, it is proposed according to the invention to first determine the composition of the removed chemical solution and then the consumed proportions of z. As sulfite, alkaline component, quinone component or water or alcohol to supplement to restore the given composition for the next digestion. This supplementary step is also called strengthening.

It is to be regarded as a significant advantage of this measure that the chemical solution especially when removing before digestion, but also at removal after digestion no or very few Contains substances, when reusing the starched chemical solution for the next digestion as disturbing prove. The method according to the invention, that it turns off, during the impregnation an oversupply of digestion chemicals to disposal So, despite the initially seemingly uneconomical Procedure of high chemical use work extremely economically, because the removal or the separation and the strengthening of the Chemical solution can easy and inexpensive carried out become.

The inventive method is specifically controlled so that only as little as possible of the used Starting material is degraded or dissolved. The aim is to produce a pulp which contains a lignin content for softwood of at least 15% based on the otro fiber mass, preferably a lignin content of at least 18%, more preferably 21%, advantageously at least 24%. For hardwood is sought a lignin content of at least 12% based on the otro fiber mass to reach, preferably of at least 14%, more preferably at least 16%, preferably at least 18%. In annual plants is the preferred lignin content is between 10 and 28%, in particular between 12 and 26%.

The Yield of the process according to the invention is at least 70%, preferably more than 75%, advantageous more than 80%, in each case based on the wood used. These Yield correlates with the above lignin content of Pulp. The original one Lignin content of wood is specific to the species. The yield loss turns out in the present process predominantly as a loss of lignin In unspecific digestion methods is the proportion of carbohydrates clearly increased, z. B. because digestion chemicals are intrinsically undesirable You can also dissolve cellulose or hemicelluloses.

A Another advantageous measure is, after defibering and possibly grinding the lignocellulosic Material to remove the remaining chemical solution and one Re-use. In a preferred embodiment, this reuse can have two aspects include. For one thing, that will be during decomposed or dissolved organic matter, mainly lignin, continue to be used. For example, it is burned by process energy to win. Or it is prepared to be used elsewhere become. Second, the used and unused chemicals again prepared so that they are for a renewed, partial Digestion of lignocellulosic material can be used. To belongs the treatment of used chemicals.

To a particularly preferred variant of the method according to the invention the chemical solution used is used extremely efficiently. After pulping and possibly grinding, the pulp is washed, to the chemical solution as far as possible to displace by water. The in this washing or displacement process Contains resulting filtrate considerable Amounts of chemical solution and organic material. According to the invention, this filtrate is removed or separated chemical solution supplied before the chemical solution be strengthened and the next Excited becomes. The chemicals and organic components contained in the filtrate to disturb not digestion. As far as they still contribute to delignification while the next Provide information, their content is recorded in the chemical solution and in determining the for this amount of chemicals required. The chemicals further contained in the filtrate behave while inert for the upcoming digestion. They do not bother. The ones contained in the filtrate Organic components are also inert. you will be after the next Digestion in the treatment of the chemical solution continues to be used, either to generate process energy or otherwise.

It is considered to be particularly advantageous that by this leadership of the Filtrate less fresh water and less chemicals for digestion be used. At the same time a maximum of dissolved organic Material recorded. Even this improved use of the gone into solution organic material improves the economy of the method according to the invention.

details the method according to the invention and the device will be explained in more detail below with reference to exemplary embodiments.

• – Die Ausbeute wurde durch Wägung des eingesetzten Rohstoffs und des nach dem Aufschluss erhaltenen Zellstoffs, jeweils bei 105 °C auf Gewichtskonstanz (atro) getrocknet, berechnet.
• – Der Ligningehalt wurde als Klason-Lignin bestimmt gemäß TAPPT T 222 om-98. Das säurelösliche Lignin wurde bestimmt gemäß TAPPT UM 250
• – Die papiertechnologischen Eigenschaften wurden an Prüfblättern bestimmt, die nach Zellcheming-Merkblatt V/8/76 hergestellt wurden.
• – Der Mahlgrad wurde nach Zellcheming-Merkblatt V/3/62 erfaßt.
• – Das Raumgewicht wurde nach Zellcheming-Vorschrift V/11/57 ermittelt.
• – Die Reißlänge wurde nach Zellcheming-Vorschrift V/12/57 bestimmt.
• – Die Durchreißfestigkeit wurde nach DIN 53 128 Elmendorf ermittelt.
• – Die Ermittlung von Tensile-, Tear- und Burst-Index erfolgte gemäß TAPPT 220 sp- 96.
• – Der Weißgrad wurde ermittelt durch Herstellung der Prüfblätter nach Zellcheming-Merkblatt V/19/63, gemessen wurde nach SCALA C 11:75 mit einem Datacolor elrepho 450 × Photometer; die Weiße ist in Prozent nach der ISO-Norm 2470 angegeben.
• – Die Viskosität wurde bestimmt nach dem Merkblatt IV/36/61 des Vereins der Zellstoff- und Papier-Chemiker und -Ingenieure (Zellcheming).
• – Sämtliche %-Angaben in diesem Dokument sind als Gewichtsprozent zu lesen, soweit nicht im einzelnen anders angegeben.
• – Die Angabe "otro" in diesem Dokument bezieht sich auf "ofentrockenes" Material, das bei 105 °C bis zur Gewichtskonstanz getrocknet wurde.
• – Die Chemikalien für den Aufschluss sind in Gewichtsprozent als Natriumhydroxid angegeben, soweit nicht anders erläutert.

The following tests were evaluated according to the following rules:

• The yield was calculated by weighing the raw material used and the pulp obtained after the pulping, in each case dried at 105 ° C. to constant weight (atro).
• The lignin content was determined as Klason lignin according to TAPPT T 222 om-98. The acid-soluble lignin was determined according to TAPPT UM 250
• - The paper technology properties were determined on test sheets, which were prepared according to Zellcheming leaflet V / 8/76.
• - The degree of grinding was recorded according to Zellcheming leaflet V / 3/62.
• - The density was determined according to Zellcheming regulation V / 11/57.
• The breaking length was determined according to Zellcheming regulation V / 12/57.
• - The tear resistance was determined according to DIN 53 128 Elmendorf.
• Tensile, tear and burst index were determined according to TAPPT 220 sp-96.
• - The whiteness was determined by preparing the test sheets according to Zellcheming leaflet V / 19/63, was measured according to SCALA C 11:75 with a Datacolor elrepho 450 × photometer; the whiteness is given in percent according to ISO standard 2470.
• - The viscosity was determined according to the leaflet IV / 36/61 of the Association of Pulp and Paper Chemists and Engineers (Zellcheming).
• - All% figures in this document are expressed as weight percent unless otherwise specified.
• - The term "otro" in this document refers to "oven-dry" material that has been dried to constant weight at 105 ° C.
• - The chemicals for the digestion are given in percent by weight as sodium hydroxide, unless otherwise stated.

Example 1 - Softwood pulping in the liquid phase

A mixture of spruce wood and Douglas fir chips was added after a damping (30 minutes with saturated steam at 105 ° C) with a sodium sulfite pulping solution at a liquor ratio of wood: digestion solution 1: 3. The total use of chemicals was less than 15% based on otro woodchips. The pH at the beginning of the digestion was adjusted to pH 6 by addition of SO ₂ .

The with chemical solution impregnated Spruce wood chips were over a period of 90 minutes at 170 ° C heated and over Opened for 60 minutes at this maximum temperature.

Subsequently was the free-flowing liquid removed by centrifugation, collected and in an array to return unused liquid analyzed and strengthened and so for the next digestion provided.

The Open-minded wood chips were shredded. Subsets of the so produced pulp were ground for different lengths to the To determine strength at different degrees of grinding. The energy expenditure for defibering the partially digested chips was less than 300 kWh / t of pulp.

The Yield in this experiment was 77% based on the used Carpentry and joinery.

These corresponds to a pulp with a lignin content of well over 20%. The average lignin content for spruce wood is 28% given in relation to the otro wood mass (Wagenführ, Anatomie des Holzes, VEB Fachbuchverlag Leipzig, 1980). The actual lignin content of the pulp is higher than 20% since while digestion predominantly, but not exclusively lignin is reduced. Also carbohydrates (cellulose and hemicelluloses) are dissolved in small quantities. The values given show that the digestion has good selectivity on the lignin and carbohydrate degradation has.

Of the whiteness lies with values of over 55% ISO is unexpectedly high and thus provides a good starting point for a possibly subsequent Bleach, in the whiteness of 75% ISO are achievable.

At a final grinding degree of 12 ° SR, these fabrics already have 6 km of breaking length with a specific gravity of 1.87 cm ³ / g.

In order to grind the fibers to a degree of grinding of 15 ° SR, a grinding time of 20 to 30 minutes is required. The meal develops up to a grinding time of 20 minutes (freeness 12 ° SR-15 ° SR) regardless of the pH at the beginning of the digestion (pH 6 to pH 9.4) in a narrow corridor.

Also independently from the initial pH of the digestion and that required to reach the freeness Grinding time becomes a high level of strength at a grind level of 15 ° SR reached.

Example 2

Of the Pulp was made from spruce wood chips, the pH at the beginning of the digestion was 9.4.

In addition to 15% total chemicals (sulfite and NaOH in predetermined proportions) the chemical solution 0.1 anthraquinone added based on the amount of wood used.

The Duration of digestion was 60 minutes.

The following values resulted: Yield (%): 81.1 lignin: 22.7 Whiteness (% ISO): 53.7 Tear length (km): 9.6 Tear resistance (cN, 100 g / m ² ): 75.0

By The addition of 0.1% anthraquinone may reduce the duration of digestion of about 180 minutes under otherwise unchanged digestion conditions be reduced to 60 minutes. This time gain is valuable, above all, because the plants for pulp production smaller can be dimensioned. additional Savings potential This is because the temperature required for the digestion only over one much shorter Period must be maintained.

Farther it was determined that with decreasing use of total chemicals to values between 5 and 15% for softwood pulp with largely equal good properties is generated. These results are not dependent on the use of anthraquinone. The anthraquinone causes an acceleration of the digestion, but the desired pulp can be opened up without the addition of anthraquinone.

Example 3: Hardwood pulping in the liquid phase

eucalyptus wood chips were after the damping with a sodium sulfite digestion solution a fleet ratio of wood digestion solution Offset 1: 3. The chemical usage here was 10.5% (as NaOH) on otro wood chips.

in the Period of 90 minutes, the pulp was impregnated and the food is heated to the maximum digestion temperature of 170 ° C. The cooking time was 50 minutes.

Outcrops with Eucalyptus wood shows that these substances with a specific Energy input for defibering of less than 250 kWh / t produce to let.

The yield in these experiments was 77% based on the wood pulp used. In an initial freeness of 14 SR these substances have 3.5 km tearing length at a specific of 2.05 cm ³ / g. These substances bleached to whiteness of 79.6% ISO in the following bleach.

tries have shown that the outcrops show a low overall time requirement in the vapor phase. Compared to the Digestion in the liquid Phase is the heating to the maximum digestion temperature much faster. The actual digestion then needs the same duration as boiling in the liquid phase. During the Vapor-phase digestion, there is no free-flowing chemical solution this will be after impregnation and deducted before digestion. It is therefore less organic Material added as the chemical solution after digestion in the liquid Phase is subtracted. On the quality of the produced pulp however, this has no significant impact.

While in vapor phase digestions similar values can be achieved in the yield, the Whiteness of the pulp produced during steam pulping, however, significantly lower. A significant effect is the reduction of the maximum digestion temperature from 170 ° C to 155 ° C: the whiteness increases.

The in the vapor phase produced fibers have excellent Strengths on. The tear length was for example measured at 10 km and 11 km at 15 ° SR. The tear resistance was measured, for example, at 82.8 cN and 91.0 cN. These Values correspond to the best values for high lignin fibers, the for outcrops in the liquid Phase have been reached or are still over. For fibers with a high lignin content from the prior art comparable strength values are not known.

Out The examples show particularly clearly that the fibrous materials according to the invention only require a small amount of energy during grinding to build up high tear lengths, without the tear resistance is reduced. Grinding degree 12 ° SR was reached in 0-10 minutes each; Grinding degree 13 ° SR 5-30 minutes, usually 10-20 minutes. In order to reach grinding degree 14 ° SR, the Jokro mill needed 30-40 minutes work and for Grinding degree 15 ° SR were needed between 35 and 40 minutes. It is obvious, that a grinding up to grinding degrees around 40 ° SR a huge effort Would require grinding energy. A particular advantage of the method according to the invention is therefore in it to see that with little expenditure of energy to be milled fibers be produced with high strengths.

Claims (19)

Method for producing wood pulp or annual plants with a lignin content of at least 15% for softwood, of at least 12% for Hardwood and of at least 10% for annual plants, respectively referring to the otro fiber mass, with the steps - Produce a chemical solution with more than 5% chemicals (calculated as NaOH) for softwood or with more than 3.5% chemicals (calculated as NaOH) for hardwood or with more than 2.5% of chemicals (calculated as NaOH) for annual plants, each related to the otro amount of wood - Mix the chemical solution with wood or annual plants in a given liquor ratio - heating the chemical solution and the wood or annual plants to a temperature above room temperature and subsequently - either (1st alternative) Remove free-flowing chemical solution and Unlock the Wood or annual plants in the vapor phase or (2nd alternative) Unlock the Wood or annual plants in the liquid phase and separating the free-flowing chemical solution and of wood or annual plants. Method according to claim 1, characterized in that that a pulp containing at least 15% lignin, preferably at least 18% lignin, preferably at least 21% lignin, in particular at least 24% lignin based on otro pulp for softwood or containing at least 14% lignin, preferably at least 16% lignin, more preferably at least 18% lignin based on otro pulp for Hardwood or containing at least 10% lignin, preferred at least 12% lignin, in particular at least 19% lignin on otro pulp for Annual plants is produced. Method according to claim 1 or 2, characterized that for the preparation of the chemical solution, a quinone component is used. Method according to one of the preceding claims, characterized characterized in that for the decomposition of softwood at most 15% chemicals, preferably used between 9 and 11% chemicals become. Method according to one of the preceding claims, characterized characterized in that for the digestion of hardwood at most 10% chemicals, preferably between 4 and 10% chemicals, especially between 6 and 8% chemicals are used. Method according to one of the preceding claims, characterized characterized in that for the digestion of annual plants at most 10%, preferably between 3 and 10% chemicals are used. Method according to one of the preceding claims, characterized characterized in that for the production of the chemical solution sulfites and sulfides, used singly or in admixture. Method according to claim 7, characterized in that that for the preparation of the chemical solution, an acidic and / or a alkaline component, in particular an acid, sulfur dioxide, sodium hydroxide and / or a carbonate is used. Method according to one of the preceding claims, characterized in that for the digestion of an alkaline component and an acidic component, in particular SO ₂ are used, wherein the ratio of alkaline component: SO ₂ in a range of 4: 1 to 1.6: 1, preferably set to 2: 1. Method according to one of the preceding claims, characterized characterized in that the method at a pH between 6 and 11, preferably between 7 and 11, more preferably between 7.5 and 10 performed becomes. Method according to one of the preceding claims, characterized characterized in that a liquor ratio wood: chemical solution between 1: 1.5 and 1: 6, preferably between 1: 3 and 1: 5 is set. Method according to one of the preceding claims, characterized characterized in that the heating of the chemical solution and the wood or annual plants up to 130 ° C, preferably up to 120 ° C, advantageous up to 110 ° C he follows. Method according to one of the preceding claims, characterized characterized in that the heating of the Wood or the annual plants and possibly the chemical solution to to 90 minutes, preferably up to 60 minutes, advantageously up to 30 Minutes, most advantageously lasts up to 10 minutes. Method according to one of the preceding claims, characterized characterized in that the unraveling of the wood or the annual plants at temperatures between 120 ° C and 190 ° C, preferably at temperatures between 150 ° C and 180 ° C, more preferably at temperatures between 160 ° C and 170 ° C is performed. Method according to one of the preceding claims, characterized characterized in that the unraveling of the wood or the annual plants up to 180 minutes, preferably up to 90 minutes, more preferably up to 60 minutes, advantageously up to 30 minutes, particularly advantageous takes up to 2 minutes. Method according to claim 15, characterized in that that the duration of the digestion dependent on from the liquor ratio chosen becomes. Method according to one of the preceding claims, characterized characterized in that the consumption of chemicals during the Digestion up to 80%, preferably up to 60%, more preferably up to 40%, advantageously up to 20%, particularly advantageous up to 10% of the chemicals used at the beginning of the digestion. Method according to one of the preceding claims, characterized characterized in that the composition of the removed or separated chemical solution recorded and then for the renewed use for the production of fibers on a given Composition is set. Method according to one of the preceding claims, characterized characterized in that after defibering and optionally grinding the digested lignocellulosic material released chemical solution removed is and is supplied to a re-use.