FI103588B - A process for the production of raw materials for artificial and other fibers from herbaceous plants - Google Patents

Description

103588

Process for the production of raw materials for man-made fibers and other fibers from herbaceous plants

The invention relates to a process for the preparation of pulp from herbaceous plants and the like using a two-step soup, first a formic acid cooking followed by a soup in formic acid and hydrogen peroxide. After cooking, if desired, bleaching is performed with oxidizing bleaching chemicals. The pulp thus prepared is particularly useful in the manufacture of textile yarns, non-woven products, wadding, viscose fibers, other fibers based on modified cellulose and fine paper. The invention also relates to the use of the pulp thus obtained in the manufacture of textile yarns, non-woven products, wadding, viscose fibers, other fibers based on modified cellulose and fine paper. The invention further relates to a process for the production of viscose fiber and fine paper using herbaceous plants as a raw material. The invention also relates to the viscose fibers and fine paper thus obtained.

The production of viscose fibers from herbaceous plants is difficult by conventional methods because the herbaceous plants contain many substances which cause great problems in the viscose process and also affect the quality of the product; 25 ways. In particular, high levels of ash, extract, silicate and calcium (2 - 10%) of grasses cause · 1; problems, because staying in too high concentrations • · makes it difficult to filter viscose. Also problematic are herbaceous trace elements which act as catalysts for the viscose process and disrupt the stability of the process.

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In traditional time processes, such as the sulphate process, the silicates dissolve in the cooking but in the 6 recovery they concentrate and the chemicals have to be removed to the sewage, causing environmental problems. For this reason, in industrialized countries, 2 103588 processes cannot be used to make soluble cellulose and still viscose. Another disadvantage of alkaline digestion is that much of the nutrients and metals remain in the pulp during the cooking step and cause problems in subsequent process steps, especially in generalized peroxide bleaching.

In the past, the problem has also been that the viscose fiber raw material and the fine paper raw material had to be manufactured mainly by different processes. It has now been found that the pulp produced by the process of the invention can also be used, with good results, to produce fine paper.

The most important factor in fine paper manufacturing is the short fibers of the bleached chemical pulp, which provide good printing properties of the paper. The fibers of herbaceous plants are thinner and, in many varieties, half shorter than hardwoods, which allows by nature to obtain a suitable ratio of paper to opacity and smoothness without grinding.

20 Fine papers include printing, writing and drawing paper and paperboard. Much of the fine paper is printed before the paper is used up. Fine papers are made from wood-free pulp and generally contain less than 10% mechanical pulp. Used as fresh fibers. 25 mainly birch and pine sulphate pulp and mechanical pulp • · * .. *.

··; Fine papers are subject to certain quality standards, the most typical of which are high brightness and good everyday V * performance.

[0006] U.S. Patent Application No. 933729 describes a process: V: for the preparation of cellulose from wood or annual plants: * · * by cooking with dilute acetic acid under pressure and addition of formic acid. The cooking is carried out at a high temperature of 130-190 ° C with acetic acid 35 in a concentration of 50-95% by weight and formic acid in a concentration of less than 40%.

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Fl patent 74750 describes a process for preparing bleached cellulose pulp from lignin-containing cellulosic feedstock by treating it with a cooking broth containing organic peroxoic acids. The peroxoacids are obtained by adding hydrogen peroxide to an organic carboxylic acid such as formic, acetic, propionic and butyric acid. The cooking is carried out at a temperature of about 70 to 90 ° C. Bleaching is then carried out with an alkali solution containing hydrogen peroxide. In addition to deciduous and coniferous nor-10 paint, one-year plants, grass, straw and bagasse can be used as raw materials. In the examples of the publication, the method has been applied solely to wood material.

The preferred range of amounts of hydrogen peroxide used in the process of said FI patent 74750 is 5 to 20% by weight, based on the amount of dry cellulose raw material. The cooking times are preferably 4-6 hours.

The process of FI patent 74750 may further comprise a pretreatment step with formic acid. It is mentioned in the publication that the formic acid treatment is preferably carried out at an acid boiling point (101 ° C or slightly higher). In Example 5 of the patent, the formic acid treatment is carried out at 90 ° C.

Seisto et al., Milox Pulping of Agricultural Plants, International Symposium on Wood and Pul-. 25 ping Chemistry, Helsinki June 6, 10, 1995, pp. 407-414 and • · in Seisto A. et al., Grass Pulp for Papermaking, "··· * by the Peroxyformic Acid Pulping Method, 1995 Pulping Conference. , Chigago 1 Oct-5 Oct 1995, pp. 487-494 describes the preparation of pulp from herbaceous plants by subjecting herbaceous plants to a two-stage cooking, followed by a formic acid cooking followed by a soaking of formic acid and hydrogen peroxide. According to Table 2 on page 409 of Seisto et al., the first 35 steps, the formic acid step, the boiling temperatures range from 100 to 120 ° C and the boiling times from 45 to 180 minutes. The second step has a cooking time of 3 hours and hydrogen peroxide amounts. 1.5 - 5% (based on the grass feedstock) When performing the first cooking step in the higher 5 temperature ranges from 105 ° C upwards (110 and 120 ° C) to the second stage hydrogen peroxide the amounts vary between 2 and 5% (based on the raw material). In addition, one experiment was performed using a single-stage formic acid soup without a hydrogen peroxide step (0% H 2 O 2).

10 In Seiston et al. Oh. publications mainly deal with the effect of cooking conditions on kappa. It is generally noted that the kappa number increased as the amount of hydrogen oxide decreased. It is also mentioned that with longer cooking times the amount of fines increases which causes problems in dewatering and that raising the temperature to 120 ° C had the same effect. To eliminate the fines problem, spring harvesting or fractionation of the raw material is suggested.

The present invention relates to a process for the environmentally friendly production of pulp from herbaceous plants and the like, wherein the herbaceous plants are subjected to a biphasic cooking process, first comprising formic acid cooking at a temperature above 100 ° C and then formic acid cooking at a temperature of 70-90 ° C. , and after cooking, if desired, bleaching using oxidizing bleaching chemicals.

The process according to the invention is characterized in that the first stage has a cooking temperature of 105-125 ° C, a cooking time of 30 minutes in the first and second cooking stages of 15 minutes to 1.5 hours and the amount of hydrogen peroxide used in the second t ·: * · *: 1-3% by weight in the cooking stage.

In the context of the present invention, the term "herbaceous plants and the like" generally refers to non-wood fiber sources. Among the most useful 5,103,588 sources of fiber can be mentioned straw, e.g. cereal straw (rice, wheat, rye, oats, barley), hay, e.g., esparto, sabai and lemon grass, reeds, e.g. papyrus, lake reed, sugar cane and bamboo, so-called fibers, e.g., Kha-5 double flax stalks, oil flax stalks, kenaf, jute and hemp, deciduous fibers, such as manila hemp and sisal, and seed hairs such as cotton and cotton lint fibers.

The herbaceous plants grown in Finland and useful in the present invention may include reed canary grass, timothy, dogwood, yellow fescue, eastern blubber, red foxglove, white clover, goat pea and bat.

The term "herbaceous plants and the like" in the context of the present invention also includes short-fiber hardwood and young thinning wood.

In the process according to the invention, all the above non-wood fiber plants can be used as raw material. The herbaceous plants used as a raw material, such as lake reed, do not need to be pre-treated e.g. by fractionation-20 to reduce ash and silicates or by grinding, but the stems, leaves, knots and cones of herbs can be cooked directly as they are harvested from shredding long stalks and leaves. In contrast, in known methods, where silicates cannot be separated, the pre-treatment of feeds has been used to reduce the problems caused by the silicates mechanically, e.g. by removing the sugarcane core or chemically, e.g. by acid hydrolysis or ·. hot-water. In such a pretreatment, 30 biomasses are lost and the most important short fibers are lost in the papermaking process, which is not the case according to the invention. in this method.

In the production of fine paper, short-fiber hardwoods and young rare-chopped hardwoods with a fiber length shorter than rope 6103588 can also be used as raw materials. The economics of using thinned logs is best when using a whole wood recovery method, such as a pulp chips method, whereby pure chips are used for the production of specialty fibers.

In the process of the invention, the herbaceous plants are first led to a first cooking step which is carried out in formic acid using a high temperature above 100 ° C which according to the invention is 105-125 ° C.

The high temperature ensures better solubility of organic and inorganic compounds without degradation of formic acid and damage to the fibers.

The concentration of formic acid solution used in the first step is generally 70 to 90%, preferably 80%.

The solid to liquid ratio in the first 15 cooking steps is generally in the range 1: 4 to 1: 8, preferably 1: 4 to 1: 4.5. This ratio is advantageously achieved in practice by adding to the cooking solution containing the cooking solution grasses to be treated, e.g., lake reed, for 5-10 min from the start of the liquid feeding, whereby the cooking chemistry-20 liters reduces the volume of the mattress.

The material to be treated from the first cooking step is conducted to the second cooking step which is carried out at a lower temperature of 70 to 90 ° C, preferably at about 80 ° C. Formic acid is used as the cooking solution. 25 poles with added hydrogen peroxide. The concentration of formic acid solution is 70-90%, preferably 80%. The amount of hydrogen peroxide to be added in the second step of the process of the invention is 1 to 3% by weight. This amount of hydrogen oks · · V · peroxide is lower than that of the above-described Seiston et al. The amounts of hydrogen peroxide used in the publications are from 2 to 5% by weight of the raw material (corresponding to about 5 to 14% by weight) when carrying out the first stage cooking at temperatures above 105 ° C (110 and 120 ° C).

The cooking times for the first and second cooking steps-35 may range from 15 minutes to 1.5 hours. The cooking times 7 103588, especially for the second cooking step, are thus shorter than those of Seisto et al. used in publications (cooking time of the second cooking step 3 h).

The other acids formed in the process, namely acetic acid, lactic acid, propionic acid and methyl formate, can be recycled as a mixed acid from cooking liquor to another cooking step where heavier acids than formic acid form more stable peroxy compounds and increase the efficiency of the peroxy acids. The decomposition of the peroxides is slower and the use in cooking is thus enhanced, requiring a smaller amount of hydrogen peroxide (1 to 2.5%) than, for example, the process according to the aforementioned FI Patent 74750 where the amount of hydrogen peroxide used is more than 4%. The aggressiveness of peroxy formic acid has thus been reduced and a more uniform product has been guaranteed. Methyl formate, in turn, assists in the formation of cellulose formate, which in turn has a positive effect on the production of viscose fiber.

If bleached pulp is desired, bleaching with oxidizing bleaching chemicals is performed after cooking 20. The oxidizing bleaching is preferably hydrogen peroxide bleaching. In a preferred embodiment, normal hydrogen peroxide bleaching is carried out, which generally comprises 2 to 4 steps. Bleaching may be at normal pressure or under pressure. Part. . 25 of the hydrogen peroxide steps can be replaced by other oxidizing bleaching chemicals, such as oxygen or ozone.

'··· * The process also includes appropriate washing steps'. ** between the cooking and bleaching steps. The final mass washing of the second cooking step is typically carried out by pressure water washing at 115-125 ° C with water.

::: Heavier than formic acid formed in the process: * · *: acids can be partially recycled to be used in the manufacture of preservatives, for example for the preservation of feed and grain. This avoids excessive concentration of the heavy acids or their separate distillation.

8 103588

The first stage cooking may be carried out with a second stage cooking broth containing 80% formic acid plus other cooking acids such as acetic acid, lactic acid, propionic acid and other organic acids as well as acids recovered during regeneration.

In a preferred embodiment of the process, the closed water circuits associated with the acidic cooking step and the closed water circuits associated with the alkaline bleaching are kept separate. The silicates formed in the process are separated into their own product and the excess sodium is returned to the bleaching and the organic compounds are incinerated. The process uses evaporated clean water as washing water. The formic acid released from the bleaching step is separated as sodium formate and returned to the force-15 plant to bind sulfur compounds there.

In the preparation of viscose fiber, the pulp from the cooking and bleaching step treated according to the invention is typically mercerized for 30 to 60 minutes and sulfurized for 30 to 60 minutes using a conventional wood-based viscose-20 cyproc process.

Formic acid, used as a cooking chemical, dissolves plant nutrients and metals so that after washing steps, the cellulose is sufficiently free from components that interfere with viscous filtration and catalysis. Kei-. . In alkaline hydrogen peroxide bleaching after 25 tonnes, vegetable silicates dissolve in bleaching water so efficiently that they also do not cause problems in the production of viscose. Also, the plant-based extractants · · · V * are removed in cooking and bleaching so that there is no adverse effect on the viscose process or subsequent yarn production.

• · '· *; The formic acid-based process of the invention has allowed the utilization of a uniform and narrow molecular weight distribution of short-fiber arable cellulose to produce 35 uniform and high-strength viscose fibers (2.8 to 3.1 cN / dtex).

9 103588

The fibers of reed are shorter than wood fibers and can hold 6-7 times more volume than wood fibers in the same volume unit. As a result, the retention capacity of the reed fluid is much higher than that of wood fibers. This also affects 5 mercerization. The penetration of the liquor into the fibers is slower and the total reaction time is longer than that of the wood fibers. With the same mercerization time, a large amount of insoluble fiber remains which forms an adhesive layer on the viscose filters. By extending 10 mercerization times and using the catalyst, good quality viscose with a Kw value of less than 100, which is considered good enough for industrial operation, has been obtained.

In the process of the invention, the high ash, nutrient, metal and extractant content of grassy plants can be lowered in the process steps to a level which does not interfere with the viscose process and to obtain a fiber distribution that provides firm and uniform viscose. High quality cellulose is also suitable for other modified pulp downstream products. These include, for example, CMC and cellulose acetate.

In the manufacture of fine paper, the pulp obtained from the cooking and bleaching step treated according to the invention is subjected to a process for the production of fine paper, in which:. 25 is combined in a suitable proportion of wood fiber. A suitable ratio is, for example, 30% to 50% grass fibers and the rest wood fibers.

It has been found that using, for example, 50% birch fiber and 1% herbaceous plants, the fiber produced by the peroxidic acid technology of the invention produces 30 fine papers which have better properties than birch pine based fine paper.

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When wood is used as a starting material in traditional fiber-based products such as fine paper, hardwoods and their fibers must be individually milled to provide the desired fiber bonding properties and sufficient paper opacity and smoothness properties. When using grass plants with thinner and shorter fibers than hardwoods, no separate grinding is required.

It is also possible for short fibers to provide more bonding in the paper structure than for long fibers. This also allows the use of a higher amount of filler, which can further improve the surface properties of the paper and lower the price of the paper.

10 In the manufacture of fine paper from non-wood fibers, problems such as dewatering, runnability and retention have generally been encountered. The paper obtained in this way has also exhibited unsatisfactory strength, bulk density and stiffness properties. Unexpectedly, the fibrous pulp produced by the process according to the invention has succeeded in producing fine paper with good opacity, high brightness, a smooth surface, suitable gloss, good light scattering properties and high surface strength. All of these features are achievable in high-quality color printing. Electronic color printing will increase interest in such papers.

On the other hand, the requirements of new printing technology and environmental protection will increase the properties of colors and inks. The stiffer color requirements 25 also set the surface strength of the paper to the requirements of color and fiber> · · stability. The new peroxic formic acid technology * 9 has been able to demonstrate on a pilot scale that 50% short-fiber grass fiber replaces birchwood for all offset four-color printing properties over birch pine paper.

♦ ·. * J *. The peroxy formic acid process of the invention and the subsequent manufacture of viscose and fine paper can be incorporated as part of the broader set out as a process diagram in the accompanying Figures 1 and 2.

1χ 103588

As shown in Figure 1, the raw material 16 (which may be reed or lake reed) is fed to the first cooking step 1. In the first cooking step, formic acid is used as the cooking chemical, which flows upstream of the previous cooking step 2 as the The mass flow from the first cooking stage is conducted to the second cooking stage 2.

10 In the second cooking step, the formic acid solution 22 from the next step, acidic acid 3, and hydrogen peroxide, which is a chemical stream 20, are used as the cooking chemical countercurrently. partly also as a replacement chemical stream 24. There may be several acid washing steps as required. From the acid wash, the cellulose stream 25 is led to the water wash 4. The water wash 20 may be pressurized and may have several steps as required. The water used for washing the water is obtained as condensate along the conduit 28. The water from the water wash is led to regeneration after washing via pipeline 27. From the water wash cellulose 26 is led to the first bleaching step 5 and the second bleaching step 6.

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The alkaline bleaching 5 and 6 of the cellulose is performed with :: hydrogen peroxide labeled as the chemical stream 29.

· *: There may be several bleaching steps depending on the desired brightness level. Bleaching solution 5 from first bleaching step. The counter-current 30 is provided upstream of the following bleaching steps 6 • · as a stream 32 and the bleaching solution • · of the first bleaching step • is conducted to the fiber separation 11 via the conduit 30. From the first bleaching step, the cellulose 31 is led to the following bleaching steps 6. The final bleaching step 35 uses water obtained from evaporation 13 via conduit 34 and hydrogen peroxide obtained from the 12103588 chemical stream 29. The final bleaching step 33 provides the bleached cellulose stream 33.

For the regeneration of cooking chemicals 7, cooking chemicals from the first cooking stage are conducted along line 19 along the pipeline, water for washing water along line 27 and formic acid solution obtained from concentrating the hemicellulose portion along line 38. During regeneration, formic acid is distilled and returned to the acid wash 3 via conduit 23. The distillate can also be introduced to control the acid concentration also for the first and second cooking steps 1 and 2 of the en-10. Concentrated aqueous formic acid solution is returned from concentrate of hemicellulose 10 via pipeline 38 to regeneration 7. The regeneration separates acid 35 which is led to the preparation of an organic preservative 8.

The fibers are separated from the bleaching solution in fiber separation 11. The bleaching solution is led through a conduit 30 from the first bleaching step 5 to the fiber separation 11.

The fiber-containing solution 40 is passed to a filter press 14.

Bleaching water filtrate 39 is passed to ultrafiltration 12.

In ultrafiltration, particles smaller than the fibers are separated from the water and passed through a conduit 41 to a compression step 14. The ultrafiltration filtrate is led through a conduit 42 to an evaporation 13, which may be multi-step. During evaporation, water containing silicate is concentrated. 3 0 is centrifuged and purified water is returned through line 34 • · to the final bleaching stage. Concentrated water for silicate is introduced via pipeline 43 to silicate separation 15. Silicate is separated in step 15 by adjusting the pH by addition of formic acid 35 as a chemical stream 44. From silicate separation, pure water 13 103588 is led to pipeline 45 into either ultrafiltration water stream 39. From the separation of the silicate, the silicate is recovered as its own product 46. The water 47 from the leach press is returned to ultrafiltration 12 and the organic material 48 is recycled.

In the general process diagram of Figure 2, lake reed and / or reed canary grass and formic acid are introduced into a cooking step comprising the two 10 cooking steps described above. Hydrogen peroxide is also introduced into the second cooking step. The pulp obtained from the cooking step is led to a bleaching step which is carried out with hydrogen peroxide. The pulp from bleaching is used to make fine paper and viscose.

The general process diagram of Figure 2 also indicates the regeneration step after cooking, the lignin separation and the hemicellulose separation. Separation of hemicellulose yields sugars and lignin separation lignin. The diagram also shows the power plant using electricity or peat or biowaste.

The closed water cycles associated with the acidic cooking stage and the closed water cycles associated with alkaline bleaching are kept separate. The bleaching waters are treated in their own closed loop and the silicates are separated into 25 products and the excess sodium is returned to the bleaching and the organic compounds are incinerated. Evaporated clean water is used as washing water. In bleaching, · 1; formic acid is different from sodium formate, which can be taken to the power plant with organic compounds * .1. 30 to be burned to bind sulfur compounds there.

- · · j · t The process is environmentally friendly. Formic acid and hydrogen peroxide used as cooking and polishing chemicals are biodegradable. The process operates in a closed water cycle and chemicals can be recovered without problems caused by silicates or other compounds.

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In the process of the invention, both brown pulp waters and bleaching waters can be sealed. Such a closed water cycle is not described in the aforementioned FI Patent 74750. In the process of the sulfur-free and chlorine-free chemicals of the invention, the closure of the water cycle is considerably simpler than in the conventional sulfate process, which requires separate removal of sulfur and sodium. In Peroxoformic Acid Method 10, the substances contained in the plants are already soluble in the first cooking step, which is acidic and does not carry back into the process with the chemicals. The dissolved compounds are transferred to the hemicellulose fraction, where they can be utilized as nutrients for fermentation and as a circulation nutrient with power plant ash. Only the silicates do not dissolve in the broth, they are 99% soluble in the bleaching step and can be separated into their own product. Purified water can be returned to bleaching for washing water.

The following examples illustrate the invention.

Example 1

A pilot-scale experiment was conducted in which 200 kg of spring-harvested lake reed (moisture 15%) was boiled at 120 ° C using 80% formic acid 25% in the first step and 80% regenerated formic acid in the second step and as an additive. 2.5% ♦ hydrogen peroxide (by mass). The ratio of cane to · *: saline (liquid ratio) was 1: 4.5. The soups in the first and second cooking stages were 60 min.

. ·. 30 The cooked pulp was bleached using an alkaline three-phase φ · ·; ·. of them hydrogen peroxide bleaching at 80 ° C.

The pulp thus treated was made of viscose fiber by mercerizing a wet pulp containing 20% solids for 60 min and embroidering for 60 min. The index of filtration 35, i.e. the filtration constant K i, was 82. The fiber strength was 3.1 cN / dtex.

103588

The filtration constant Kw was calculated by the formula Kw = 100000 '[(2-P2 / PJ / (P1 + P2), where PT = grams of viscose spilled over a period of 0 min to 20 min, and 5 P2 = grams of viscous spilled over 20 min to 60 min. equipment with a perforated plate on which was mounted a support ring (diameter 7.9 cm leaving a free filter surface of about 49 cm 2) and filter material (cotton linen plate, Procter & Gamble / the Buckeye Cellulose Division; quality 12-FW-4 ), the backing is made of unbleached cotton.

Fiber strength was determined by stretching a single fiber until it breaks. Strength was obtained by dividing the force required for breaking by the titer of the fiber. The titer 15 is expressed as a dtex value, which represents the fiber length such that a 10,000 m long 1.0 dtex fiber weighs 1.0 g.

Example 2

A pilot-sized experiment was conducted by boiling 250 kg of 20 spring-harvested lake reeds (moisture 15%) at 105 ° C using 80% formic acid in the first step and 2.5% by weight hydrogen peroxide as an additive. The liquid ratio and cooking times were the same as in Example 1. The pulp thus treated was bleached using three-step hydrogen peroxide bleaching at 80 ° C.

The pulp thus treated was made of viscose fiber by mercerizing a wet pulp containing 20% solids for 60 minutes and embroidering for 60 minutes. The filtration constant Kw was 121. The fiber strength was 2.9 cN / dtex.

*. ·. Example 0

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·; ·. A pilot-sized experiment was conducted by boiling 200 kg of lake reed (moisture 15%) at 115 ° C using 80% formic acid (second stage cooking liquid) for the first step. The liquid ratio was the same as above. Cooking time was 35 45 min. In the second cooking step, 2.5% hydrogen peroxide was used as the 80% admixture of formic acid with a cooking time of 60 min. The pulp was bleached by a three step alkaline hydrogen peroxide bleaching.

35% of the above reed fiber, 35% of birch fiber and 30% of pine fiber were prepared using fine paper. The Pilot paper machine ran 4 km of 80 cm wide base paper weighing 80 g / m2.

The opacity, bulk, stiffness, smoothness, and filler retention were better than that of the birch-10 pine-based fine paper used for comparison: the base paper produced by the method of the invention had an opacity of 89.3% (reference 86.8%), bulk 1.20 cc / g 1.18 cm3 / g), machine stiffness 0.554 mNm and transverse direction 0.163 mNm (0.317 mNm and 0.154 mNm on reference paper), the paper roughness was 215 ml / min and 340 ml / min on the reference paper (340 ml / min and 360 on the reference paper). ml / min) and filler retention of 86.03% (84.87% on reference paper).

The base paper thus obtained was coated on both sides with 20 g of 10 g / m 2 and supercalendered. In all-color offset printing, all the major printing advantages remained better than birch-pine-based fine paper.

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Claims (20)

103588 A process for the environmentally friendly production of pulp from herbaceous plants and the like, wherein the herbaceous plants are subjected to a two-stage cooking process, first comprising a formic acid cooking at a temperature above 100 ° C and then a formic acid cooking at 70-90 ° C using hydrogen peroxide as additive , and after cooking, bleaching is performed using ha-10 oxidizing bleaching chemicals, characterized in that the first stage cooking temperature is 105-125 ° C, the cooking time in the first and second cooking steps is 15 min to 1.5 h and the amount of hydrogen peroxide used in the second cooking step is 1 to 3% by weight. Process according to claim 1, characterized in that the first cooking step is carried out in about 70-90%, preferably about 80% formic acid. A process according to claim 1, characterized in that the second cooking step is carried out at about 80 ° C in about 70-90% formic acid, preferably about 80% formic acid. Process according to one of Claims 1 to 3, characterized in that after cooking, oxidative bleaching with hydrogen peroxide is carried out. ! A process according to claim 4, characterized in that the hydrogen peroxide bleaching is carried out in a 2-4 step. ·. ·. 30 A process according to any one of the preceding claims. · · • · ·; ·. A process characterized in that the ratio of solids to cooking liquor of the herbaceous plants at the beginning of cooking is 1: 4 to 1: 8, preferably 1: 4 to 1: 4.5. A method according to any one of the preceding claims, characterized in that the reed grass is used as a herbaceous plant. 103588 Process according to one of Claims 2 to 4, characterized in that the first stage cooking is carried out with a second stage cooking broth containing 80% formic acid plus other acids formed in the cooking 5, such as acetic acid, lactic acid, propionic acid and other organic acids. acids. Method according to one of the preceding claims, characterized in that the closed water circuits associated with the cooking step 10 and the closed water circuits associated with bleaching are kept separate. Process according to one of the preceding claims, characterized in that the silicates formed in the process are separated into their own product and the excess sodium is returned to the bleaching stage and the organic compounds are incinerated. Process according to one of the preceding claims, characterized in that the evaporated clean water is used as washing water. A process according to any one of the preceding claims, characterized in that the formic acid released from the pulp step is separated off as sodium formate and returned to the power plant to bind sulfur compounds there. Use of a pulp made by the process of any of the preceding claims for the production of textile yarns, non-woven products, wadding, viscose fibers and other fibers based on '1: modified cellulose. ·. ·. 30 A process according to any one of claims 1 to 12. use of pulp produced by the process for the production of fine paper. A process for the production of viscose fibers from gastrointestinal plants and the like, comprising the cooking step, the bleaching step and the mercurization of the fiber thus obtained, characterized in that the cooking step comprises the cooking according to claim 1 and the bleaching step comprises bleaching by oxidative bleaching. chemicals. Process according to Claim 15, characterized in that the bleaching comprises hydrogen peroxide bleaching. 17. A process for producing fine paper from grassy plants and the like, comprising a cooking step, a bleaching step and a fine paper production from the pulp thus obtained, characterized in that the cooking step comprises the cooking according to claim 1 and the bleaching step comprises bleaching with oxidizing bleaching chemicals. Process according to Claim 17, characterized in that the bleaching step comprises hydrogen peroxide bleaching. Viscose fiber, characterized in that it is produced by the process according to claim 15 or 16. Fine paper, characterized in that it is produced by the process according to claim 17 or 18. > · »• · · · · · · · · · · · · · · · · · · ··· · ·