DE102007036382A1 - Lignocellulosic pulp from annual plants - Google Patents

Abstract

The invention relates to an unbleached lignocellulosic pulp of annual plants with a tearing length of more than 4.5 km at 20 ° SR and a lignin content of at least 8%, based on the unbleached otro pulp, and a bleached pulp of annual plants and two methods for its production ,

Description

The The invention relates to a lignocellulosic pulp of annual plants and a method for producing such a pulp from annual plants.

For the purposes of the present invention, the annual plants include not only grasses or parts thereof (bamboo, straw) but also fibrous plant components such as bagasse or banana peels. Lignocellulosic fibers from annual plants are used, inter alia, for the production of paper and cardboard. There are a large number of industrially produced lignocellulosic fibers known, which differ widely in their properties:
As wood pulp fibers are (also from annual plants) referred to, which are produced by mechanical defibration of the fiber composite by means of grinding or grinding units. In the production of wood pulp hardly any wood substance or lignin is broken down. The biomass originally used is found almost entirely in wood pulp. In the case of mechanical defibration of the annual plants, they are broken down into fiber bundles in milling aggregates, usually after pre-damping. 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 fibers is very low - even after mashing - because the fibers contain much native lignin and therefore have little bonding potential. They are also greatly reduced by the mechanical defibration, which impairs their recyclability. The pulp production requires high energy input.

newer Try to process wood pulp by pretreatment of annual plants with steam and / or chemicals the fiber properties improve and / or reduce energy requirements. These include in particular CTMP (Chemo-Thermomechanical Pulp) and TMP (Thermomechanical Pulp). With CTMP those in the technical application usually between 1-5% by weight of chemicals based on otro wood used to partially loosen the fiber composite to enable. Wood pulp is generally characterized due to low strength properties, in particular low tear length and especially low tear strengths, and high Opacity and light scattering with low whiteness with a high yellowing tendency.

When Pulp fibers are referred to by chemical dissolution of the fiber composite are produced from lignocellulosischem raw material. In the production of pulp, chemicals are used the most under high pressure and high temperature on the biomass Act. With more or less extensive removal of lignin and a part of the carbohydrates, so with significant loss yield, from annual plants produce fibers with good strength properties, especially high tear length and with good bleachability high whiteness and low yellowing tendency. The energy required to produce the pulp is obtained from the waste liquor of the digestion.

For the use of the fibers, the lignin content is often not critical. Critical is usually the strength level, as it is often the application areas limited. Therefore, numerous methods have been developed which try on the basis of processes of pulp production also for fibers with higher lignin content a higher one Strength level to achieve.

One such a procedure, which has occasionally established itself in practice, is the NSSC procedure. Using as little as possible Sulfite is used in technical applications with neutral to light aimed at alkaline pH values, with minimal degradation of lignin to achieve the highest possible strength of the fiber. The chemical quantities are as low as possible in practice held. Fibers produced by the NSSC process mostly used unbleached.

One Another method is the bisulfite process, which at pH values is operated by 4. Other methods, such as the force method (also called sulphate process) or the soda process, which for the production of pulps with minimal lignin content have been developed and applied to their suitability for the production of high yield pulps has been tested.

In the suitability test for such fibrous materials, it is always assumed from the practical experience that due to the high lignin content of the fiber in unground or in the low-milled state has only unsatisfactory low strengths and economic usability is not given. A good overview of high yield pulps from the wood raw material is provided by "Choosing the best brightening process", N. Liebergott and T. Joachimides, Pulp & Paper Canada, Vol. 80, No.12, December 1979, T391-T395. There, the achievable strength level is given as a function of the yield and the lignin content for unbleached pulps, which were prepared by various methods. As the lower limit for fibers usable for papermaking, the strength level is measured at 500 ml CSF (26 ° SR) and a comparative measurement is made for 300 ml CSF (41 ° SR). With yields of approx. 80%, spruce can have breaking lengths of approx. 9-10 km 500 ml CSF (26 ° SR) achieved. With further grinding, the strength values increase. These already relatively high values are achieved by digestion in the acidic pH range (bisulfite digestion, acid sulfite digestion). For fibers from neutral and alkaline outcrops (neutral sulphite digestion, power and soda digestion) significantly lower strength values are given, which also have to be produced with a multiple higher use of fiberization and grinding energy. This is indicated by the higher RPM revolutions of the PFI grinder required to achieve a freeness of 500 ml CSF (26 SR) and 300 ml CSF (41 ° SR), respectively.

For Bagasse are fibrous materials known, the z. For example, in 523 ml of CSF Tenside Factor of about 5000 and a Tear Factor of about 46 have. The whiteness of such fibers is about 35% ISO. chemicals determine the process costs, so they are possible used sparingly. CTMP pulps are becoming common manufactured with chemical quantities of 1% to 5%. At acquaintances, industrially established process for the production of high-yield fibers, z. As the NSSC process, up to 10% of chemicals are purchased used on the starting material. With such a limited use of chemicals is preferred no recovery for the recovery of Chemicals installed.

In spite of the relatively small quantities of chemicals This type of pulp production leads to a considerable Environmental, especially water pollution, not only because of of the chemical input but mainly because of the organic cargo, which is discharged into 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 cost of lost chemicals loaded.

The produced by mechanical and / or chemical means high yield fibers are used especially where not necessarily a high Final whiteness and high whiteness stability required are. You could get many more Applications open up, if the strength level could be increased.

outgoing From the described prior art, it is an object of the invention an unbleached and a bleached pulp of annual plants to provide a high at high lignin content of the fiber Strength level offers.

These Task is solved with a lignocellulosic pulp from annual plants with a tearing length of more than 4.5 km at 20 ° SR and a lignin content of at least 8% based on the unbleached otro pulp.

Of the The above-described pulp has a lignin content of at least 8% based on the otro pulp on. This lignin content is determined by determination of the Klason lignin and the acid leaching Lignins (definition for this see below). Klason lignin and acid soluble lignin together give the Lignin content of the respective pulp. The lignin content of the invention Annual plant fiber can also be quite higher especially more than 10%, more than 12% or more than 14%. The higher the lignin content of the annual plant fiber with a tearing length of more than 4.5 km at 20 ° SR is, the lower the yield losses in producing the Pulp. This increase in yield increases competitiveness of the pulp.

Of the Inventive pulp of annual plants differs from the prior art in that the fibers already at one compared to known fibers from annual plants far more lower grinding degree show high strength values. The degree of grinding is a measure of the drainage behavior a fiber suspension. At a freeness of 20 ° SR is the morphologically changed only slightly. Known fibers z. B. straw or bamboo with relatively high lignin content have a structure at 20 ° SR, which is unable to bond well to adjacent fibers - and to build up an acceptable static strength level. However, the pulp according to the invention is already at a low freeness of 20 ° SR - and thus after low expenditure of grinding energy - capable of a good one Build bond to adjacent fibers.

The achievable strength values are for annual plants with a lignin content of at least 8% over 4.5 km. values more than 5 km, more than 6 km and - preferably - from more than 7 km of breaking length at 20 ° SR each are readily available for these fibers.

However, the pulp of annual plants according to the invention is not only distinguished by high tear lengths. Rather, the strength level is high overall. Thus, the annual plant fiber according to the invention with a lignin content of more than 8% at 20 ° SR and based on a leaf weight of 100 g / m ^{2 has} a tear strength of at least 45 cN. This tear resistance in connection with the high breaking lengths even at such unusually low grinding degrees of 20 ° SR for annual plants is from the prior art not known.

simultaneously the pulp has a high lignin content of more than 8% an unusually high degree of whiteness. After this Digestion, ie without any sheet metal treatment, becomes values of 40% ISO and more measured. It is also readily possible values of over 50% ISO. As the lignin in general It is regarded as coloring for the pulp, it is remarkable if, despite the high lignin content such a whiteness is achieved.

Becomes the pulp according to the invention a bleaching treatment subjected to, the fiber properties improve significantly. The bleaching treatment is more demanding for some applications required to the whiteness; but she is also aiming for the Adjustment and improvement of fiber properties. The bleached Fiber not only has a much higher degree of whiteness of over 60% ISO, preferably of over 65% ISO and advantageously of more than 70% ISO. Increase with the bleaching treatment the breaking lengths are more than 5.5 km, preferred more than 5.5 km, more preferably more than 7.5 km 20 ° SR. During the bleaching treatment, the puncture resistance be stabilized.

method for the production of pulp from annual plants They are like described above, known processes consisting of annual plants fibers with a relatively high lignin content of over 7%. They provide a yield of 70% or more based on the starting material used. This procedure are based on chemical and / or mechanical decomposition of the Annual plants.

It is therefore an object of the invention, process for the production of pulp from annual plants with a lignin content of more than 8%, produced with high strength fibers in an economical way can be.

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

This object is achieved with a first process for the production of pulp from annual plants with a lignin content of at least 8%, in each case based on the otro fiber mass. This first method comprises the steps:

• - manufacture of a chemical solution containing more than 5% of chemicals (calculated as NaOH), in each case based on the otro amount of annual plants used,
• Mixing the chemical solution with the annual plants in a predetermined liquor ratio,
• - Heating the chemical solution and the annual plants to a temperature above room temperature and then either (1st alternative)
• - Remove free-flowing chemical solution and
• - digestion of annual plants in the vapor phase or (second alternative)
• - digesting the annual plants in the presence of the liquid phase chemical solution and
• - Separation of the free-flowing chemical solution and the annual balance sheets.

The first method according to the invention is based thereon that for the production of high-yield fibers higher Chemical quantities are used as usual. More than 5% of chemicals are significantly above the usual Chemical quantities for technical pulp production from annual plants. This high use of chemicals provides fibrous materials with good yield and excellent strength properties. So are for annual plants with a lignin content of 8% or more at grindings of only 20 ° SR Values of more than 4.5 km, but also tear lengths measured more than 5 km and more than 6 km. This will be the desired high strength level achieved.

It is an extraordinary advantage of the invention View method that these strength values already at extremely low degrees of grinding are achieved, as previously for High yield pulps were not available. Annual plant fibers according to the prior art show at Mahlgrade of 20 ° SR an unacceptable level of strength. Known pulps have at these low degrees of grinding so far result in fibers that no have shown sufficient bonding capacity and the Accordingly, no sufficient strength properties for have offered an economic use of such fibers.

By contrast, the fibrous materials produced by the process according to the invention have tear lengths of more than 4.5 km to more than 7 km and tear strengths of more than 45 cN to more than 60 cN, even at degrees in the range of 20 ° SR, based on a sheet weight of 100 g / m ² . These low levels of grinding are moreover achieved with a low specific requirement of milling energy, which may even be less than 300 kWh / t of pulp. The realization that the high level of strength is already achieved at low grinding degrees of around 20 ° SR and below is an essential part of the invention.

These high strength values are not yet known for pulp from annual plants with a lignin content of more than 8%. However, the high strength level can also be maintained for fibers with an even higher lignin content. The method according to the invention is also suitable for the production of annual fiber crops having a lignin content of more than 10%, preferably more than 12%, advantageously more than 14%, based on the fiber mass.

The for producing a pulp of annual plants with a Yield of at least 70% or with a lignin content of at least 8% of the amount of chemicals to be used according to the invention is for the first method according to the invention at least 7%, in each case related to the otro mass of annual plants. The quality of the produced Fibrous material shows the best results in a chemical use of up to 30% related to otro annual plants. To be favoured between 10% and 27.5%, more preferably between 10% and 20% Chemicals based on the used otro annual plants added. An optimal use of chemicals has proved to be the best between 10% and 15%.

Setting a specific pH is by no means required for the first method of the invention. 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 first method according to the invention, irrespective 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 amounts, usually well below 1%, it is negligible for setting this ratio. A ratio of alkaline component: SO ₂ in a range of 4: 1 to 1.6: 1 is well suited to carry out the first method 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).

• – Herstellen einer Chemikalienlösung mit weniger als 20% Sulfit (berechnet als NaSO₃), jeweils bezogen auf die otro Menge der eingesetzten Einjahrespflanzen,
• – Mischen der Chemikalienlösung mit dem Holz in einem vorgegebenen Flottenverhältnis,
• – Erwärmen der Chemikalienlösung und des Holzes auf eine Temperatur über Raumtemperatur und anschließend entweder (i. Alternative)
• – Entfernen frei fließender Chemikalienlösung und
• – Aufschließen der Einjahrespflanzen in der Dampfphase oder (2. Alternative)
• – Aufschließen der Einjahrespflanzen in Gegenwart der Chemikalienlösung in flüssiger Phase und
• – Separieren der frei fließenden Chemikalienlösung und der Einjahrespflanzen.

The object underlying the invention is also achieved with a second process for the production of pulp from lignocellulosic raw material with the steps:

• Preparing a chemical solution with less than 20% sulphite (calculated as NaSO ₃ ), in each case based on the otro amount of the annual plants used,
• Mixing the chemical solution with the wood in a predetermined liquor ratio,
• - heating the chemical solution and the wood to a temperature above room temperature and then either (i. Alternative)
• - Remove free-flowing chemical solution and
• - digestion of annual plants in the vapor phase or (second alternative)
• - digesting the annual plants in the presence of the liquid phase chemical solution and
• Separate the free-flowing chemical solution and the annual plants.

The The inventive method is based on that for the production of high-yield fibers a minimum of chemicals is used. Despite the low use of chemicals yields the inventive method fibers with good yield and excellent strength properties. So be for annual plant fiber with a lignin content of more than 8% after the second invention Processes are prepared at grinding degrees of only 20 ° SR values of more than 4.5 km, but also tear lengths of measured more than 5 km and more than 6 km. This will be the desired high strength level achieved.

In the first method according to the invention, it is believed that the quality of the high yield pulp of annual plants produced there is due to the high chemical input of more than 5% (calculated as NaOH). Experiments have shown, however, that a pulp with the same qualities can certainly also be produced if smaller amounts of sulfite are used and if the use of alkali, eg. B. of NaOH or Na ₂ CO _{3 is} omitted. The demand for sulfite in the second method according to the invention can be reduced by 10% to 50%, in most cases by 20% to 40%, usually by 25% to 35%, compared to the first method.

This is a significant advance on the one hand achieved in the process costs. On the other hand, the second method of the invention works much more environmentally friendly, because a total of a minimum of chemicals is used to produce a particularly high quality and versatile fiber. In addition, only a small and therefore particularly economical and environmentally friendly chemical reprocessing is required to complete the cycle of this process. Which of the two methods according to the invention is used depends on the compound to be disrupted Raw material and on the requirements of the produced pulp.

The second inventive method is according to a advantageous embodiment for the production of high-yield fibers used from annual plants. These high strength values are for pulps of annual plants with a lignin content of more than 8% so far unknown. The high strength level But it can also be used for fibrous materials with an even higher Lignin content can be maintained. The invention Method is also suitable for the production of fibers from annual plants with a lignin content of more than 10%, preferably more than 12%, advantageously more than 14% based on the otro fiber mass.

The The advantages described above apply without restriction for high yield pulps from annual plants, those according to one of the methods of the invention were manufactured. It is an extraordinary advantage View the inventive method that the described strength values already at extreme low degrees of grinding are achieved, as previously for High yield fibers combined with high strength values were not available. Fibers from annual plants show the state of the art at grindings of 20 ° SR an unacceptable level of strength. Known pulps have at these low degrees of grinding so far result in fibers that no have shown sufficient bonding capacity and the Accordingly, no sufficient strength properties for have offered an economic use of such fibers.

By contrast, the fibrous materials produced by the process according to the invention have tear lengths of more than 4.5 km and tear strengths of more than 45 cN, even at degrees in the range of 20 ° SR, based on a sheet weight of 100 g / m ² . These low levels of grinding are also achieved with a low specific requirement of milling energy lower than 250 kWh / t of pulp. The realization that the high level of strength is achieved even at low degrees 20 ° SR and below is an essential part of the invention.

The Composition of the chemical solution used for digestion May be in agreement with the wood to be split and the desired pulp properties are set. As a rule, only one sulfite component is used. alternative or in addition, a sulfide component may be added. Digestion with a sulfite component is by the presence not disturbed by sulfide components. Technically, mostly Sodium sulphite, but also the use of ammonium or potassium sulfite or magnesium bisulfite is possible. When in the first method according to the invention high levels of sulfite can be used on a alkaline component can be dispensed with, because even without adding Alkaline components sets a high pH, the digestion favored.

to PH adjustment and delignification support can for the first method according to the invention an acidic and / or an alkaline component are added. The alkaline component is usually sodium hydroxide (NaOH) used. But it is also possible to use carbonates, especially sodium carbonate. The information on chemical quantities of the first digestion process according to the invention in this document, e.g. B. for the total use of chemicals or Distribution of the sulphite component and the alkaline component, are calculated and indicated, unless otherwise stated as sodium hydroxide (NaOH). The information on chemical quantities of the second inventive method in this Document are each calculated and given as sodium sulfite.

As the acidic component, acids can be added for the first process according to the invention 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 regarded as an independent inventive achievement for both methods according to the invention to have recognized the advantages of using a quinone component for the high-yield digestion according to the invention. Quinone components, particularly anthraquinone, have heretofore been used in the manufacture of pulps with minimal lignin content to prevent unwanted attack on the carbohydrates towards the end of the digestion. The addition of quinone components makes it possible to continue the digestion of annual plants until almost complete degradation of the lignin. It has been found to be an unprecedented, unexpected property of quinone components that significantly increase the rate of lignin degradation in the production of high yield pulps. The duration of the digestion can z. B. in the production of annual plant fiber by more than half, depending on digestion conditions shortened by more than three quarters. This remarkable effect is achieved with minimal use of quinone. It is expedient to use z. B. anthraquinone zwi 0.005% and 0.5%, advantageously 0.025-0.2% anthraquinone, particularly advantageously 0.025-0.1% anthraquinone used. 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 is used for the inventive method a chemical solution produced. Mostly an aqueous solution is used. As an option, the use or the addition of organic Solvents are provided. Alcohol, in particular Methanol and ethanol, in combination with water are particularly effective Chemical solutions for the production of high quality High-yield fibrous materials. The mixing ratio of Water and alcohol can be used for each raw material be optimized few attempts.

The inventive methods can in a wide pH range can be performed. The relationship from alkaline component to acidic component or use an acid or an alkaline component may be at the first be set according to the invention method that at the beginning of the process, a pH between 5.5 and 11, preferably adjusted between 5.5 and 10, more preferably between 7.5 and 8.5 becomes. The more alkaline pH's between 8 and 11, which are responsible for the process according to the invention are advantageous also the effect of the quinone component. The invention Methods are tolerant to pH; it is especially at second inventive method no or Little chemicals required for pH adjustment. This works auspicious on the cost of chemicals.

Without further addition of acid or alkaline component at the end of the digestion, a pH between 5.5 and 10, usually between 7.5 and 8.5 in the free-flowing chemical solution and the dissolved therein organic components, the were liquefied by the digestion. To the solved ones Organic ingredients include mainly lignosulfonates.

The Fleet ratio, so the ratio of the amount the otro annual plants to the chemical solution, becomes set between 1: 1.5 and 1: 6 for both methods. A liquor ratio of 1: 3 to 1: 5 is preferred. In This area is a good and easy mix and impregnation ensured of the material to be opened. For annual plants becomes a liquor ratio of 1: 4 preferred.

The Mixture or impregnation of the annual plant-wood chips is preferably at elevated temperatures. A heating the chips and the chemical solution up to 170 ° C, preferably up to 150 ° C, more preferably up to To 130 ° C leads to a fast and even Digestion of annual plants. For mixing or Impregnating the wood chips is a period of up to to 30 minutes, preferably up to 60 minutes, more preferably advantageous for up to 90 minutes. The optimal period of time depends among other things on the amount of chemicals and the Fleet ratio and the type of digestion (liquid or vapor phase).

Of the Digestion of mixed with the chemical solution or impregnated lignocellulosic material is preferably carried out at temperatures between 120 ° C and 190 ° C, preferably between 150 ° C and 180 ° C. For the most Annual plants will have breakdown temperatures between 155 ° C and 170 ° C set. Higher or lower temperatures can be adjusted but in this temperature range stand the energy expenditure for the heating up and the acceleration the digestion in an economic relationship to each other. Higher temperatures can also be negative affect the strength and whiteness of the pulp. The pressure generated by the high temperatures can by appropriate Design of the stove can be caught easily. Usually The duration of the heating is only a few minutes, usually up to 30 minutes, advantageously up to 10 minutes, in particular, when heated by steam. The duration of the heating up can up to 90 minutes, preferably up to 60 minutes, z. For example is digested in the liquid phase and the chemical solution to heat together with the chips.

The duration of the digestion is chosen especially depending on the desired pulp properties. The duration of the digestion can be shortened to up to 2 minutes, z. B. in the case of a vapor phase digestion of annual plants with low lignin content. But it can also be up to 180 minutes, if z. B. the digestion temperature low and the natural lignin content of aufzuschließenden annual plants is high. Even if the initial pH of the digestion is in the neutral range, a long digestion time may be required. Preferably, the digestion time is up to 90 minutes. Particularly preferably, the digestion time is up to 60 minutes, advantageously up to 30 minutes. A digestion time of up to 60 minutes is particularly suitable for annual plants with low lignin content. The use of a quinone component, in particular anthraquinone, allows a reduction of the digestion time to up to 25% of the time required without the addition of anthraquinone. Will on the Dispensing with quinone components, 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 of the invention Procedure is the duration of digestion depending on set by the selected fleet ratio. The lower the fleet ratio, the shorter the process duration can be set.

The Production of high-yield pulp according to the first invention High chemical use of more than 5% for annual plants, as according to the first invention Proposed method appears initially uneconomical. But experiments have shown that only a part of the chemicals during the partial digestion of the lignocellulosic material consumed becomes. The vast majority of chemicals are left unused discharged, either before digestion (vapor phase digestion) or after digestion (digestion in the liquid phase). The actual consumption of chemicals is below that in the Digestion solution amounts used.

Of the Chemical consumption is proposed for both inventions Procedure is recorded as the amount of chemicals that - related to the originally used amount of chemicals - after removing or separating the chemical solution as well if necessary, detecting chemical solution after defibering or in conjunction with a detection of the chemical solution is measured. The consumption of chemicals depends on the absolute amount of used for the digestion Chemicals, based on the otro mass to be broken down at annual plants. The higher the use of digestion chemicals is, the lower is the direct sales of chemicals. At a Use of 27.5% chemicals based on otro annual plant mass for the first method according to the invention, For example, only about 30% of the chemicals used are consumed. at Use of 15% chemicals related to otro annual plants However, 60% of the chemicals used consumed, as in laboratory experiments could be detected. The consumption of chemicals for the first method according to the invention according to a preferred embodiment of the method during digestion up to 80%, preferably up to 40%, 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 softwood). According to the invention suffices this amount of chemicals according to the first proposed method, to produce a pulp with the given properties. However, a uniform process result to ensure and possibly special, desired To obtain pulp properties, it can according to the first inventive method as meaningful prove to use higher quantities of chemicals for digestion, z. As the aforementioned up to 30% chemicals based on otro Annual Plant Pulp.

Of the Use of these chemicals at the beginning of the digestion shows advantageous in the first method according to the invention Effect, since the fibrous materials obtained in this way not yet available properties, in particular high strength properties and have high degrees of whiteness. In particular, so far no Digestion methods available that have a broad pH spectrum from neutral to alkaline fiber with high Strengths generated. As economically attractive it turned out that the inventively produced Fibers with much lower energy consumption to specified Ground grinding grades are known fibrous matter from annual plants. In addition, they develop the high strengths already at unusual low grinding degrees of 20 ° SR.

A surplus of chemicals is in both of the invention Method after mixing and impregnating the annual plants with the chemical solution or after digestion in the free flowing liquid. This surplus is before digestion (1st alternative) or after digestion (2nd alternative) deducted.

According to an advantageous development 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 digestion of annual plants no longer has the initial 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 for both methods of the invention, the composition of the removed chemical solution first to determine and then the consumed shares of z. As sulfite, alkaline component, quinone component or water or alcohol to supplement to restore the predetermined 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 even more so when removing before digestion, but also when removed after digestion contains no or very few substances that are when reusing the starched chemical solution for the next digestion as disturbing prove. The first method according to the invention, that it turns off, during the impregnation an oversupply can provide for pulping chemicals So despite the initially uneconomical appearing Procedure of high chemical use extremely work economically, because the removal or separation and Strengthening the chemical solution can be easy and be carried out inexpensively.

The inventive methods are targeted so controlled that only as little as possible of the starting material used degraded or dissolved. The aim is to have a pulp produce at least 4% lignin based on the otro fiber mass preferably at least 5% lignin, more preferably at least 6% lignin, preferably at least 7% lignin.

The Yield of the inventive method is at least 70%, preferably more than 75%, advantageously at more than 80%, in each case based on the annual plants used. This yield correlates with the lignin content indicated above of the pulp. The original lignin content of annual plants is specific to the species. The yield loss poses predominantly as loss in the present process at lignin. In unspecific digestion process is the proportion significantly increased in carbohydrates, z. B. because digestion chemicals in an undesirable manner also cellulose or hemicelluloses bring in solution.

A Another advantageous measure is, after defibering and optionally grinding the lignocellulosic material remaining one Chemical solution to remove and re-use. This reuse can be more preferred for both methods Embodiment two aspects. For one thing, that will be during of the partial digestion degraded or dissolved organic material, predominantly lignin, continues to be used. It is burned, for example, to gain process energy. Or it is prepared to be used elsewhere. To the others are the used and unused chemicals again so prepared that they are for a renewed, partial Digestion of lignocellulosic material can be used. This includes the treatment of used chemicals.

To a particularly preferred variant of the invention Procedures, the chemical solution used is extraordinary used efficiently. After pulping and possibly grinding, the pulp becomes Washed to the chemical solution as much as possible to displace by water. That in this washing or Displacement process resulting filtrate contains considerable amounts of chemical solution and organic material. According to the invention this Filtrate of the removed or separated chemical solution fed before the chemical solution strengthened and the next digestion is supplied. The in the filtrate contained chemicals and organic components do not disturb the digestion. As far as they still have a contribution for delignification during the next digestion their salary is recorded in the chemical solution and in determining the required for this digestion Chemical quantity considered. The further in the filtrate contained chemicals behave during the upcoming Digestion inert. They do not bother. The ones contained in the filtrate Organic components are also inert. They are going to the next digestion of the chemical solution used further, either to generate process energy or on other way.

It is considered to be particularly advantageous that through this leadership Filtrate less fresh water and less chemicals for the digestion can be used. At the same time, it becomes a maximum detected dissolved organic material. Also this improved Use of the dissolved organic material improves the economy of the invention Process.

in the Following are ways to manufacture as well as essential properties of the fibrous material according to the invention on the basis of exemplary embodiments explained in more detail.

• – Die Ausbeute wurde durch Wägung des eingesetzten Rohstoffs und des nach dem Aufschluss oder der Bleiche erhaltenen Faserstoffs, jeweils bei 105°C auf Gewichtskonstanz (otro) getrocknet, berechnet.
• – Der Ligningehalt wurde als Klason-Lignin bestimmt gemäß TAPPI T 222 om-98. Das säurelösliche Lignin wurde bestimmt gemäß TAPPI UM 250
• – 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 Opazität wurde nach den Vorschriften des Zellcheming-Merkblatts VI/1/66 bestimmt.
• – Die papiertechnologischen Eigenschaften wurden an Prüfblättern bestimmt, die nach Zellcheming-Merkblatt V/8/76 hergestellt wurden.
• – Raumgewicht wurde nach Zellcheming-Vorschrift V/11/57 ermittelt.
• – Reißlänge wurde nach Zellcheming-Vorschrift V/12/57 bestimmt.
• – Die Durchreißfestigkeit wurde nach DIN 53 128 Elmendorf ermittelt. Sie wird für ein Blatt mit einem Blattgewicht 100 g/m² angegeben.
• – Der Mahlgrad wurde nach Zellcheming-Merkblatt V/3/62 erfaßt.
• – Die Ermittlung von Tensile-, Tear- und Burst-Index erfolgte gemäß TAPPI 220 sh-96.
• – Alle Prozentangaben in diesem Dokument sind Gewichtsangaben, soweit nicht anders vermerkt.

The properties of the fibers were recorded and measured according to the following standards:

• The yield was calculated by weighing the raw material used and the pulp obtained after the digestion or bleaching, in each case dried at 105 ° C. to constant weight (otro).
• The lignin content was determined as Klason lignin according to TAPPI T 222 om-98. The acid-soluble lignin was determined according to TAPPI UM 250
• - 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 in percent after the ISO standard 2470 specified.
• - The opacity was determined according to the specifications of Zellcheming leaflet VI / 1/66.
• - The paper technology properties were determined on test sheets, which were prepared according to Zellcheming leaflet V / 8/76.
• - Volumetric weight was determined according to Zellcheming regulation V / 11/57.
• Tear length was determined according to Zellcheming Regulation V / 12/57.
• - The tear strength was after DIN 53 128 Elmendorf determined. It is given for a leaf with a leaf weight of 100 g / m ² .
• - The degree of grinding was recorded according to Zellcheming leaflet V / 3/62.
• Tensile, Tear and Burst Index were determined according to TAPPI 220 sh-96.
• - All percentages in this document are by weight unless otherwise stated.

First invention method

Example 1 - Digestion in liquid phase

Bagasse-chips are after a damping (30 minutes with saturated steam with 105 ° C) with a sodium sulfite digestion solution at a liquor ratio of bagasse: digestion solution Offset 1: 3. The total amount of chemicals used was 27.5 on otro bagasse wood chips. The pH at the beginning of the digestion was adjusted to pH 8.5 to 9.5.

The Bagasse chips impregnated with chemical solution were over a period of 90 minutes at 170 ° C. heated and over 30 minutes at this maximum temperature open minded.

Subsequently The free flowing liquid was centrifuged removed, collected and in a return arrangement unused liquid analyzed and strengthened and so provided for the next digestion.

The open-minded bagasse wood chips were defibered. subsets of the thus-produced pulp were ground for various lengths to To determine the strength at different degrees of grinding. The energy expenditure for shredding the partially digested bagasse wood chips was less than 300 kWh / t of pulp.

Example 2

Bagasse-chips Become a 27.5 chemical additive at a liquor ratio of wood: chemical solution = 1: 5 at 120 ° C in the vapor phase impregnated for 120 minutes. When Chemicals are sulfite and 0.1% anthraquinone used. At the start the impregnation sets a pH of 9.4. After impregnation, the chemical solution away.

The woodchip impregnated with the chemical solution are heated with steam in about 5 minutes at 170 ° C. This vapor phase at 170 ° C is about 15-20 Minutes kept. then the steam is drained and within 30 seconds, the cooker is cooled to 200 ° C, and ambient pressure is established. The wood chips are the Cooker removed and shredded. Subsets of the thus prepared Bagasse pulp is ground and ground for the Partial quantities are determined by grinding degree and pulp properties.

Second invention method

Example 1 - Digestion in liquid phase

Bagasse-chips are after a damping (30 minutes with saturated steam with 105 ° C) with a sodium sulfite digestion solution at a liquor ratio of wood: digestion solution Offset 1: 3. The total use of chemicals was calculated at 15% as sodium sulfite, based on otro bagasse wood chips.

The Bagasse chips impregnated with chemical solution were over a period of 90 minutes at 170 ° C. heated and over 30 minutes at this maximum temperature open minded. The initial pH was in the range of pH 8.0 to 9.5.

Subsequently The free flowing liquid was centrifuged removed, collected and in a return arrangement unused liquid analyzed and strengthened and so provided for the next digestion. Strengthening means that the given sulphite concentration by adding fresh or recycled sulfite again is set for the next digestion. The chemical consumption in this first digestion is 82%.

The open-minded bagasse wood chips were shredded. Aliquots of the pulp so produced were ground for different lengths to determine the strength at different degrees of grinding. The energy required to shred the partially digested bagas sen-wood chips was less than 300 kWh / t of pulp.

The yield is 79.2% based on otro pulp. The tenacity was measured at 16 ° SR at 4.5 km, the Tear index at 7.0 mN · m ² / g. The whiteness was determined after digestion at 41% ISO.

Example 2

Bagasse-chips be with 23.6% sulfite at a liquor ratio of Wood: Chemical solution = 1: 5 at 120 ° C in the Vapor phase impregnated for 120 minutes. As chemicals sulfite and 0.1% anthraquinone are used. At the beginning of the impregnation a pH of 9.4 is reached. After impregnation the chemical solution is removed.

The woodchip impregnated with the chemical solution are heated with steam in about 5 minutes at 170 ° C. This vapor phase at 170 ° C is over 20 minutes held. Then the steam is released and within 30 seconds the cooker is cooled to 100 ° C and it stops ambient pressure. The wood chips are taken from the stove and frayed. Subsets of the thus prepared bagasse pulp will be ground and for the ground subsets Grinding degree and pulp properties determined.

At 16 ° SR, 5 km tenacity and 102 cN / 100 g / m ² paper weight were measured. The whiteness was determined to be 42.6% ISO and the yield was 78.9%.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - ISO standard 2470 [0062]
• - DIN 53 128 [0062]

Claims (36)

Lignocellulosic pulp from annual plants with a tearing length of more than 4.5 km at 20 ° SR and a lignin content of at least 8% based on the otro pulp in the unbleached state. Fiber according to claim 1, characterized that the lignin content of the unbleached pulp is at least 10%, preferably at least 12% and advantageously at least 14% of the otro Fiber is. Fiber according to claim 1, characterized that the breaking length is more than 5 km, preferably more than 6 km, more preferably more than 7 km. Fibrous material according to claim 1, characterized in that it has a tear resistance which is at least 45 cN at 20 ° SR at a sheet weight of 100 g / m ² . Fiber according to claim 1, characterized that the clay bleached pulp has a whiteness of at least 35% ISO. Lignocellulosic pulp from annual plants with a tearing length of more than 4.5 km at 20 ° SR and a lignin content of at least 7% based on the otro pulp in the bleached state. Fibrous material according to claim 6, characterized that the pulp with a lignin content of more than 7% relative on the otro pulp after bleaching a whiteness of at least 60% ISO. Fibrous material according to claim 6, characterized that the bleached pulp has a whiteness of more than 65% ISO, preferably of more than 70% ISO. Fiber according to claim 7, characterized that the bleached pulp at 20 ° SR has a breaking length more than 5 km, preferably more than 6.5 km, preferably from has more than 7.5 km .. Fiber according to claim 7, characterized that the bleached pulp with a lignin content of more than 7% at 20 ° SR a tear resistance of more than 45 cN. Process for producing pulp from annual plants with a lignin content of at least 8% relative to the otro fiber mass, with the steps - Make a chemical solution with more than 5% chemicals (calculated as NaOH), in each case on the otro amount of annual plants - Mix of the chemical solution with the annual plants in one predetermined fleet ratio - heating of the chemical solution and the annual plants on one Temperature above room temperature and then - either (1st alternative) Remove free-flowing chemical solution and Digestion of annual plants in the vapor phase - or (2nd alternative) Unearthing the annual plants in the liquid phase and separating the free-flowing Chemical solution and annual plants. Process for producing fibrous material from lignocellulosic raw material comprising the steps of: - preparing a chemical solution containing less than 20% sulphite (calculated as NaSO ₃ ) based on the otro amount of the lignocellulosic raw material - mixing the chemical solution with wood in a predetermined liquor ratio - heating the chemical solution and the wood to a temperature above room temperature and then - either (1st alternative) removing free-flowing chemical solution and digesting the wood in the vapor phase - or (2nd alternative) digesting the wood in the liquid phase and separating the free-flowing chemical solution and the wood. Method according to claim 11 or 12, characterized a pulp containing at least 8% lignin is preferred at least 10% lignin, preferably at least 12% lignin, especially advantageously produced at least 14% lignin based on otro pulp becomes. Method according to claim 11 or 12, characterized that for the preparation of the chemical solution sulfites and Sulfides, used singly or in mixture. Method according to claim 11, characterized in that that for the preparation of the chemical solution an acidic and / or an alkaline component, in particular an acid, sulfur dioxide, Sodium hydroxide and / or a carbonate is used. A method according to claim 11, characterized in that for digestion 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 to 2 : 1 is set. Method according to claim 14, characterized in that that for the preparation of the chemical solution sodium, potassium, Magnesium and / or ammonium sulfites are used. Method according to claim 11 or 12, characterized that for the preparation of the chemical solution, a quinone component is used. Method according to claim 11, characterized in that that for digestion 10 chemicals or more, preferably 12% chemicals or more, more preferably 15% chemicals or more become. Method according to claim 11 or 12, characterized that the process at a pH between 5.5 and 11, preferred between 5.5 and 10, more preferably between 7.5 and 8.5 becomes. Method according to claim 11 or 12, characterized that a liquor ratio annual plants: chemical solution between 1: 1.5 and 1: 6, preferably between 1: 3 and 1: 5 becomes. Method according to claim 11 or 12, characterized that heating the chemical solution and the Annual plants up to 170 ° C, preferably up to 150 ° C, advantageously up to 130 ° C. Method according to claim 11 or 12, characterized that heating the annual plants and possibly the chemical solution up to 90 minutes, preferably up to 60 minutes, advantageously until to 30 minutes, especially advantageous lasts up to 10 minutes. Method according to claim 11 or 12, characterized that digesting the annual plants at temperatures between 120 ° C and 190 ° C, preferably at temperatures between 150 ° C and 180 ° C, particularly preferred at temperatures between 160 ° C and 170 ° C is performed. Method according to claim 11 or 12, characterized that digesting 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 25, characterized in that that the duration of the digestion depends on is chosen from the fleet ratio. Method according to claim 11, characterized in that that the consumption of chemicals during the digestion up to 80%, preferably up to 40%, particularly preferably up to 40%, advantageously up to 20%, particularly advantageously up to 10% of the chemical use at the beginning of digestion. Method according to claim 12, characterized in that that for digesting lignocellulosic raw material with a lignin content of more than 14% based on otro raw material Up to 13% sulphite based on otro lignocellulosic raw material be consumed that to digest lignocellulosic Raw material with a lignin content of 12% to 25% based on otro Raw material can be consumed up to 10% sulphite, and that for digesting lignocellulosic raw material with a lignin content of up to 10% based on otro raw material less than 10% sulphite consumed, but at least 5% sulfite can be used. Method according to claim 12, characterized in that that the consumption of sulphite during the digestion up to 80%, preferably up to 60%, more preferably up to 40% of Sulfite is used at the beginning of the digestion. Method according to at least one of the preceding Claims, characterized in that for the production the chemical solution up to 75 wt .-% of the sulfite the return of already used for digestion Chemical solution is used, and that at least 25 wt .-% of the sulfite are added fresh. Method according to claim 30, characterized that for the preparation of the chemical solution up to 50 wt .-% of sulfite from the return of already to Digestion of used chemical solution is used, and that at least 50% by weight of the sulfite is added fresh. A method according to claim 30 or 31, characterized in that in the preparation of the chemical solution fresh sulfite is added in the following amounts: up to 13% for lignocellulosic raw material of more than 25% lignin based on otro raw material, up to 10% for lignocellulosic raw material a lignin content of 20% to 25% based on raw material and less than 10% for lignocellulosic raw material with a lignin content of less than 20%, calculated in each case as NaSO ₃ based on otro lignocellulosic raw material. A method according to claim 11 or 12, characterized in that the composition of the removed or separated chemical solution detected and subsequently for re-use for producing fibers is adjusted to a predetermined composition. Method according to claim 11 or 12, characterized that after defibering and optionally grinding the digested lignocellulosic Material released chemical solution is removed and a further use is supplied A method according to claim 11, 12 or 34, characterized characterized in that by recycling the digestion solution the solids content of this circulating digestion solution by up to 5%, preferably by up to 10%, more preferably by up to 15% increases. A method according to claim 11, 12, 34 or 35, characterized characterized in that the circulated digestion solution has a calorific value up to 1.5 MJ / kg higher than a freshly prepared digestion solution.