JP2009516086A - New pulp and pulping methods. - Google Patents

Abstract

  The present invention relates to a new pulp. It is obtained from a lignocellulose material that is stirred in an aqueous tetraalkylammonium salt solution under microwave irradiation. The invention also relates to a method for pulping lignocellulosic material and a method for softening lignocellulosic material. The material to be treated is preferably wood, softwood or hardwood.

Description

  The present invention is directed to new pulp. It is derived from lignocellulosic material stirred in an aqueous tetraalkylammonium salt solution under microwave irradiation. The present invention is also directed to methods for pulping lignocellulosic materials and methods for softening lignocellulosic materials.

Pulp Pulp is a raw material for the production of paper, paperboard, fiberboard and similar industrial products. In purified form, it is the source of rayon cellulose, cellulose esters, and other cellulose-derived products.

  Fibrous plants are derived from plant fibers. Therefore, it is a renewable resource. Pulp has been used as a resource for stationery (eg papyrus) since the earliest Babylonian and Egyptian civilizations.

The origin of papermaking, which is the formation of a cohesive sheet by recombination of separated fibers, originated from Ts'ai-Lun using bamboo, mulberry bark and rags in China in the year 105 It is thought that the result. The use of wood as a papermaking resource was not commercially applied until the mid-1800s. The main wood-pulpation methods used today, such as groundwood, soda, sulfur dioxide (SO ₂ ) or acidic sulfite, and sulfate or kraft methods are 1844, 1853, 1866. , And 1870, respectively. Since their development, the basic methods have been improved and adapted. And the technology is very sophisticated.

Like most industries, as well as many research efforts to develop the most energy efficient and clean methods for manufacturing, environmental and energy concerns in the 1970s have resulted in significant changes in the operation of pulp and paper mills. I let you. In many cases, short-term practical results have added methods (eg, scrubbers, dust collectors, reservoirs, etc.) that minimize waste discharge.
Other trends include improved groundwood methods, removal or minimization of pulp quality, the use of single layers in harvesting and chipping, sulfur compounds that give off odors in pulping and corrosive chlorine compounds resulting from bleaching. Is to increase the utilization of high-yield pulp.

  Prior to the pulping process, the wood is processed by harvesting, barking, chipping and screening processes. The purpose of chipping for pulping is to reduce the wood to a size that allows penetration and diffusion of processing chemicals without undue fiber cutting or damage. A chip about 20 mm long is quite free flowing and can be transported pneumatically or on a belt. It can then be stacked or stored in a container (Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd edition, p. 379-391).

  Current pulp can be subdivided into mechanical pulp and chemical pulp.

  The aforementioned mechanical pulp is subdivided into groundwood pulp, thermomechanical pulp (TMP) and chemical thermomechanical pulp (CMTP). Ground pulp is prepared by pressing the wet wood against a wet rotating grindstone with the wheel axis parallel to the wooden axis. The temperature around the area to be polished can be 180-190 ° C. Water movement and pulp removal control and extinguish heat. Therefore, charring of wood is prevented. After such treatment, the groundwood pulp contains a significant proportion (70-80% by weight) of fiber bundles, broken fibers and particles in addition to the individual fibers. The fiber is essentially a wood that keeps the original cell wall lignin intact. They are therefore very stiff, bulky and do not collapse like chemical pulp fibers. Since groundwood pulp is obtained with a yield of about 95%, their costs are relatively low. The main direct cost other than wood is electricity. It is usually about 49-75 kJ (11.7-17.9 kcl) / ton on paper grade.

Thermomechanical pulp (TMP) is prepared by presteaming them at 110-150 ° C. to make the wood chips malleable. When heated above the glass transition point of wet lignin, wood thermoplasticization occurs. These chips with high consistency, when taken in fiber refiner, across the individual fibers are unleashed, separation occurs at the middle, ribbon-like material is prepared from S ₁ layer of the cell wall. The amount of fibrillization depends on the purification conditions. It is also important for the properties of the pulp. This material has a high light scattering coefficient, albeit lower than the light scattering coefficient of ground wood. It is also very flexible and provides good bonding to paper and surface smoothness. Increasing the proportion of long fibers enhances the tearing properties of TMP-pulp, but this portion of fibers is stiff and contributes little to bonding. There is much less fiber crushing than ground pulp.

  Chemical thermomechanical pulp (CTMP) is prepared in the same way as TMP, but the chips are gently pretreated with sodium sulfite at pH 9-10. In this process, the chips are impregnated with chemicals, steamed at 130-170 ° C. and subsequently purified. The yield is 90-92%, which is 2-3% lower than TMP. Although a range of properties can be obtained by adjusting the working variables, in general, CTMP pulp has a much higher fiber and lower particle ratio than the same type of thermomechanical pulp. Intact fibers are softer than TMP fibers, and therefore better sheet formability and bonding properties are obtained. There are reports that CTMP pulping is particularly suitable for pulping high-density hardwood.

  In chemical pulping, enough lignin is dissolved from the middle layer to separate the fibers with little, if any, mechanical action. However, some of the cell wall lignin is retained in the fiber. And attempts to remove it during cooking will result in excessive degradation of the pulp. For this reason, about 3-4% by weight of lignin usually remains in the hardwood chemical pulp and 4-10% by weight remains in the softwood chemical pulp. If it is intended to produce a pulp that is completely degraded and removed, the lignin is subsequently removed by separation bleaching.

  The concentration of cooking liquor in contact with the wood affects the rate of delignification. Delignification proceeds slower in the center of the chip at the center of the chip because it takes time for the chemical to diffuse through the tissue and decrease the reagent concentration as the chemical penetrates the chip. In order not to overheat the main part of the pulp, cooking is usually stopped before the center of the larger chip is properly delignified. Hence, the resulting pulp contains some of the pieces of wood that have not been broken down into fibers. It is separated by screening. It is then returned to the digester or mechanically broken down into fibers.

  The dominant chemical wood-pulp process is the kraft process or the sulfate process. The alkaline pulping solution or cooking solution contains sodium hydroxide and sodium sulfide in a ratio of about 3: 1. The name of Kraft (meaning power in German) was produced when the cooking liquor contained sodium sulfide compared to the pulp obtained if only sodium hydroxide was used as in the original soda process. Characterize stronger pulp. An alternative term, the sulfuric acid method, comes from the use of sodium sulfate, such as a makeup chemical in the recovery process. Sodium sulfate is reduced to sodium sulfide by organic-derived carbon in the recovery furnace.

  A solution of sodium sulfide and sodium hydroxide is in an equilibrium state as shown in the following formula.

Therefore, water-soluble sodium sulfide is a source of hydroxide ions and must be considered when adjusting the chemical charge. The development of certain systems in the North American industry put them on an equivalent basis by expressing both sodium hydroxide and sodium sulfide as equivalents to sodium oxide (Na ₂ O). The percentage of sodium sulfide in the mixture is known as the degree of sulfidation when both sodium sulfide (Na ₂ S) and sodium hydroxide (NaOH) are expressed as Na ₂ O. The chemical charge, solution composition, heating time, and reaction time and temperature are a function of the species or seed mix being digested and the intended use of the pulp. For the production of bleachable-grade pulp for good quality paper, the typical combination of Southern pine chip conditions is 18% active alkali, 25% sulfidity, liquor to wood ratio -ratio) 4: 1, 90 minutes at 170 ° C. in the first heating zone and 90 minutes at 170 ° C. in the second zone. Hardwood requires lower vigorous conditions, mainly due to lower initial lignin content.

  The craft method is a highly developed, malleable and efficient method, but has several problems and disadvantages for its use. Efforts are being made to minimize energy, water and chemical requirements at individual factories. In addition, the chemistry of this method originally has two problems. That is, formation of organosulfur compounds that give low yields of carbohydrates and odors.

One improvement of the craft process that has been applied commercially is the polysulfide process. When elemental sulfur is added to a solution of sodium sulfide and sodium hydroxide, the sulfur dissolves and has the general formula Na ₂ S _x (where x is 2-5, equilibrium conditions and how much sulfur is added. Complex mixture). Sulfur Na ₂ S _x is an oxidant, and under the conditions of kraft pulping, it converts the function of hemiacetal into a relatively alkali-stable aldonic acid. The increase in yield by the polysulfide process is proportional to the amount of sulfur added at about 10% based on wood.

One additional pulping method is sulfite pulping. In the original sulfite pulping process, wood was pulped with an aqueous solution of sulfur dioxide (SO ₂ ) and lime. Calcium sulfite has very limited solubility when pH 2 is exceeded. Excess SO ₂ gas was then maintained in the digester to keep the pH below the aforementioned level. Therefore, this method can be compared with a kraft method or a soda method which becomes an acid method. Currently, bases other than calcium are used with SO ₂ solutions. And sulfite pulping refers to various methods in which the entire pH range is utilized for all or part of pulping. Magnesium, sodium, and ammonia are used in place of calcium. Magnesium sulfide is less soluble at pH above 5, while sodium sulfite and ammonium sulfite are soluble at pH 1-14.

  In addition to the pulping methods discussed previously, there are several semichemical pulping methods. The distinction between semi-chemical methods and high-yield chemical methods is very small. In addition, the distinction between the mechanical method and the total chemical method becomes even more important. The semi-chemical method is essentially a chemical delignification that stops the chemical method at the point where mechanical processing is required to separate the fibers from the partially digested chips. Any known chemical method can be used to produce semi-chemical pulp. This pulp is less flexible but is more similar to chemical pulp than mechanical pulp. This is because it does not depend on the rupture of the fiber wall for bonding. The yield is 60-85% with a lignin content of 15-20%. Lignin collects on the fiber surface.

Microwave From recent literature on organic synthesis, it is known that when the energy required for the reaction to occur is directed to a system that uses microwave irradiation, the reaction time of the organic reaction decreases noticeably. A commonly used frequency for microwave energy is 2.45 GHz. There is a wide and continuously increasing literature available in the field of using microwave technology in organic synthesis. An example of a summary article on this topic was published by Mingos in 1994 (D. Michael P. Mingos), "Microwaves in chemical synthesis". ”, Chemistry and industry, Volume 1, August 1994, p. 596-599). Loupy et al. Recently published a review of heterogeneous catalysis under microwave irradiation (Loopy, A. (Loupy, A.), Pettit, A. (Petit, A.), Hamerin, J. (Hamelin, J.), Texier-Boullet, F., Jachault, P., Matthe, D., “Intensive New solvent-free organic synthesis using focused microwave, "Synthesis", 1998, p. 1213-1234). Another representative article was published by Strauss (CR Strauss, “A combinatorial approach to the development of Environmentally Benign Organic Chemical Preparations ")", Aust. J. chem., 1992, 52, p. 83-96).

Microwave in Mechanical Pulp Canadian Patent No. 00008526 (CA2008526) discloses the production of pulp using microwave heating of a soaked lignocellulosic material. The soaking is carried out with a state-of-the-art pulping solution (Na ₂ SO ₃ -solution) in the presence of a catalyst and a chelating agent. Subsequent to the above-described chemical penetration, material is produced by irradiation in a microwave transmission digester. This is followed by a separate mechanical purification step. The main advantage of microwave treatment is reduced cooking time and energy consumption.

  Scott et al. (TAPPI Fall Technol. Trade Fair, p. 667-676), “Microwaveving logs for energy savings and improved paper” properties for mechanical pulps ")". This treatment is carried out as a pretreatment for mechanical pulping without any further chemical penetration. The energy consumption of the next mechanical pulping was reduced to 15% of the maximum power usage level. Clearly, the wood material was softened by the rapid evaporation of water and the rapid tearing of such lignocellulosic material.

Microwave in Wood and Cellulose Degradation Finnish Patent No. 20031156 (FI20031156) discloses a microwave-assisted method of dissolving lignocellulosic material in an ionic liquid. This dissolution is complete and can be applied to any kind of lignocellulosic material, including softwood and hardwood. This dissolution must be carried out under conditions where water is substantially absent. The dissolved material components can be separated from the resulting ionic liquid solution.

  Rogers et al. Announced in 2002 the method of dissolving pure cellulose fibers in ionic liquids in the microwave field (Swatloski, RP), Spear SK, Holbray, JD ( Holbrey, JD), Rogers, RD, Journal of American Chemical Society, 2002, 124, p. 4974-4975). Also here, this dissolution has to be carried out in the substantial absence of water.

  Other non-derivatized organic solvents for cellulose are widely described in “Comprehensive Cellulose Chemistry”, Volume 1, Wiley-VCH, p. 59-67. In addition, different aqueous tetraalkylammonium hydroxide solutions have proven to be effective solvents for cellulose. Complete dissolution is achieved immediately. The aforementioned solvents are not practical in cellulose derivatization because water is always present in excess.

Canadian Patent No. 2008526 Finnish Patent No. 20031156 Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd edition, p. 379-391 D. Michael P. Mingos, "Microwaves in chemical synthesis", Chemistry and industry, volume 1, 1994 8 Moon, p. 596-599 Loopy, A. (Loupy, A.), Petit, A. (Petit, A.), Hamerin, J. (Hamelin, J.), Texier-Boullet, F., Yachaur, P. (Jachault, P.), Matthe, D., “New solvent-free organic synthesis using focused microwave”, Synthesis ("Synthesis"), 1998, p. 1213-1234. CR Strauss, “A combinatorial approach to the development of Environmentally Benign Organic Chemical Preparations”, Aust. J. chem., 1992 52, p. 83-96. Scott et al., "Microwaving logs for energy savings and improved paper properties for mechanical pulps", TAPPI Fall Technol. Trade Fair , P. 667-676. Swatloski, RP, Spear SK, Holbrey, JD (Holbrey, JD), Rogers, RD, Journal of American Chemical Society ), 2002, vol. 124, p. 4974-4975. “Comprehensive Cellulose Chemistry”, Volume 1, Wiley-VCH, p. 59-67.

  Pulp is important and one of the most energy consuming industries in the world. Due to climate change, continuous population growth, and such energy consumption, there is a great demand for new, energy-efficient production technologies in all sectors of industry. In pulping, removal or minimization of malodorous sulfur compounds would be an additional advantage.

  The object of the present invention is to provide a new pulp material.

  Another object of the present invention is to provide a method for pulping lignocellulosic material.

  A further object of the invention is to provide a method for softening lignocellulosic materials.

  Further objects will become apparent from the following description and from the claims.

  It is known that cellulose is completely dissolved in the aforementioned tetraalkylammonium hydroxide aqueous solution. It is also known that wood dissolves in ionic liquids in conditions that are substantially free of water.

  In the microwave field, when a test was conducted to dissolve cellulose in wood material in tetraalkylammonium hydroxide aqueous solution, it was surprising that it was lignin in wood material, not cellulose, that was dissolved in saline. It was discovered.

  Surprisingly, substantial delignification was performed, and stirring could be carried out in such a way as to complete that the cellulose remained intact as a bundle of thin and long fibers. The present invention provides a new type of pulp and a process for preparing it.

  By adjusting the salt concentration and the stirring time, delignification was avoided. At the same time, the wood material softened dramatically.

  In both delignification (pulping) and softening of the lignocellulosic material, a surprisingly short treatment was sought in order to reach the aforementioned results. Lignocellulosic materials such as wood were already either delignified or softened after stirring for 1 minute in a microwave field.

  According to the present invention, a new pulp is provided. The pulp comes from lignocellulosic material stirred in an aqueous tetraalkylammonium salt solution under microwave irradiation.

  Agitation can be performed with or without agitation of the lignocellulosic material in the aforementioned solution.

  The lignocellulosic material can be virtually any lignocellulosic material. The main source of pulp fibers is soft wood and hardwood wood. Other resources include straw, plants, and tow. Pulp fibers can be extracted mainly from any vascular plant found in nature. Also, straw, plants (eg, rice, african flower, wheat and sabai), tows and reeds (eg, mainly bagasses or sugar cane), several types of bamboo, bast fibers (eg, burlap, It can also be extracted from non-wood resources such as flax, kenaf hemp, linen, ramie, and cannabis), leaf fibers (eg, agaba or manila hemp and sisal).

  The preferred lignocellulosic material is wood such as softwood and hardwood.

  The lignocellulosic material can be in its original form as found in nature. Or it can be partially processed. In a preferred embodiment of the invention, the lignocellulosic material consists of wood chips. That is, lignocellulosic wood was subjected to barking and chipping prior to stirring the aforementioned materials in a water soluble tetraalkylammonium salt solution under microwave irradiation.

  The lignocellulose material can be pretreated by impregnating the lignocellulosic material with water or the aqueous tetraalkylammonium salt solution described above.

  The tetraalkylammonium salt content in the aqueous solution of tetraalkylammonium salt can be 1 to 75% by mass, preferably 5 to 60% by mass, and most preferably 10 to 40% by mass. The cation of the tetraalkylammonium salt is represented by the following chemical formula.

Here, an R ^1, R ^2, R ³ and R ⁴ are independently C ₁ -C ₃₀ alkyl group, C ₃ -C ₈ carbocyclic group or a C ₃ -C ₈ heterocyclic group. Further, the anion of the salt is halogen, pseudohalogen, perchlorate, be a C ₁ -C ₆ carboxylate or hydroxide.

  Preferably the anion is chloride or hydroxide. Most preferably, the anion is a hydroxide.

Particularly preferred tetraalkylammonium salts are those in which R ¹ , R ² , R ³ and R ⁴ are independently C ₄ alkyl groups and the anion of the salt is a hydroxide.

  When miscible with water, other organic ionic compounds can also be used as salt components in stirring the lignocellulosic material under microwave irradiation according to the present invention. Such various ionic compounds, known as ionic liquids, are described in Finnish Patent No. 20031156 (FI20031156).

  Stirring can be performed at a temperature of 40 ° C to 270 ° C, preferably at a temperature of 70 ° C to 210 ° C, and most preferably at a temperature of 120 ° C to 190 ° C.

  It is also possible to use pressure when stirring the lignocellulose material in an aqueous tetraalkylammonium salt solution under microwave irradiation. When utilized, the pressure is preferably below 20 bar, more preferably below 10 bar, most preferably between 2 and 9 bar.

  The agitation time can vary between 1 minute and 24 hours depending on the salt used and its concentration, the nature and concentration of the lignocellulosic material and possibly depending on the agitation temperature as well as the pressure utilized.

  The pulp of the present invention can be used as a raw material for producing paper, paperboard, fiberboard, and similar industrial products.

  According to the present invention, a method for pulping lignocellulosic material is also provided. In this method, the lignocellulosic material is agitated in an aqueous tetraalkylammonium salt solution under microwave irradiation to partially or fully delignify.

  In the pulping method, stirring can be performed with or without stirring the lignocellulosic material in the aforementioned solution.

  The lignocellulosic material can be virtually any lignocellulosic material. The main source of pulp fibers is soft wood and hardwood wood. Other resources include straw, plants, and tow. Pulp fibers can be extracted mainly from any vascular plant found in nature. Also, straw, plants (eg, rice, african flower, wheat and sabai), tows and reeds (eg, mainly bagasses or sugar cane), several types of bamboo, bast fibers (eg, burlap, It can also be extracted from non-wood resources such as flax, kenaf hemp, linen, ramie, and cannabis), leaf fibers (eg, agaba or manila hemp and sisal).

  Preferably, the lignocellulosic material used is wood such as softwood and hardwood.

  The lignocellulosic material can be in its original form as found in nature. Or it can be partially processed. In a preferred embodiment of the invention, the lignocellulosic material consists of wood chips. That is, lignocellulosic wood was subjected to barking and chipping prior to stirring the above materials in an aqueous tetraalkylammonium salt solution under microwave irradiation.

  The lignocellulose material can be pretreated by impregnating the lignocellulosic material with water or the aqueous tetraalkylammonium salt solution described above.

  In the pulping method, the tetraalkylammonium salt content in the aqueous tetraalkylammonium salt solution can be 1 to 75% by mass, preferably 5 to 60% by mass, and most preferably 10 to 40% by mass. The cation of the tetraalkylammonium salt is represented by the following chemical formula.

Here, an R ^1, R ^2, R ³ and R ⁴ are independently C ₁ -C ₃₀ alkyl group, C ₃ -C ₈ carbocyclic group or a C ₃ -C ₈ heterocyclic group. Further, the anion of the salt is halogen, pseudohalogen, perchlorate, be a C ₁ -C ₆ carboxylate or hydroxide.

  Preferably the anion is chloride or hydroxide. Most preferably, the anion is a hydroxide.

In the pulping process, particularly preferred tetraalkylammonium salts are those mentioned above in which R ¹ , R ² , R ³ and R ⁴ are independently C ₄ alkyl groups and the anion of the salt is a hydroxide. Salt.

  When miscible with water, other organic ionic compounds can also be used as salt components in the pulping process of the present invention. Available compounds are exemplified in Finnish Patent No. 20031156.

  In the pulping method of the present invention, stirring is performed at a temperature between 40 ° C. and 270 ° C., preferably at a temperature between 70 ° C. and 210 ° C., most preferably at a temperature between 120 ° C. and 190 ° C. Can do.

  It is also possible to use pressure when stirring the lignocellulose material in an aqueous tetraalkylammonium salt solution under microwave irradiation. When utilized, the pressure is preferably below 20 bar, more preferably below 10 bar, most preferably between 2 and 9 bar.

  The agitation time can vary between 1 minute and 24 hours depending on the salt used and its concentration, the nature and concentration of the lignocellulosic material and possibly depending on the agitation temperature as well as the pressure utilized.

  In the pulping process according to the invention, it is advantageous to select the aforementioned parameters in such a way that the delignification of the lignocellulosic material is partly or completely.

  The pulped lignocellulosic material can be used as a raw material for the production of paper, paperboard, fiberboard and similar industrial products.

  According to the present invention, a method for softening a lignocellulosic material is also provided. In this method, the lignocellulosic material is agitated in an aqueous tetraalkylammonium salt solution under microwave irradiation.

  In the softening method, stirring can be carried out with or without agitation of the lignocellulosic material in the aforementioned solution.

  In the aforementioned softening method, the lignocellulosic material can be virtually any lignocellulosic material. The main source of pulp fibers is soft wood and hardwood wood. Other resources include straw, plants, and tow. Pulp fibers can be extracted mainly from any vascular plant found in nature. Also, straw, plants (eg, rice, african flower, wheat and sabai), tows and reeds (eg, mainly bagasses or sugar cane), several types of bamboo, bast fibers (eg, burlap, It can also be extracted from non-wood resources such as flax, kenaf hemp, linen, ramie, and cannabis), leaf fibers (eg, agaba or manila hemp and sisal).

  Preferably, the lignocellulosic material used is wood such as softwood and hardwood.

  The lignocellulosic material can be in its original form as found in nature. Or it can be partially processed. In a preferred embodiment of the invention, the lignocellulosic material consists of wood chips. That is, lignocellulosic wood was subjected to barking and chipping prior to stirring the above materials in an aqueous tetraalkylammonium salt solution under microwave irradiation.

  The lignocellulose material can be pretreated by impregnating the lignocellulosic material with water or the aqueous tetraalkylammonium salt solution described above.

  In the softening method of the present invention, the content of the tetraalkylammonium salt in the aqueous solution of tetraalkylammonium salt can be 1 to 75% by mass, preferably 5 to 60% by mass, and most preferably 10 to 40% by mass. The cation of the tetraalkylammonium salt is represented by the following chemical formula.

Here, an R ^1, R ^2, R ³ and R ⁴ are independently C ₁ -C ₃₀ alkyl group, C ₃ -C ₈ carbocyclic group or a C ₃ -C ₈ heterocyclic group. Further, the anion of the salt is halogen, pseudohalogen, perchlorate, be a C ₁ -C ₆ carboxylate or hydroxide.

  Preferably the anion is chloride or hydroxide. Most preferably, the anion is a hydroxide.

In the softening method, particularly preferred tetraalkylammonium salts are those mentioned above wherein R ¹ , R ² , R ³ and R ⁴ are independently C ₄ alkyl groups and the anion of the salt is a hydroxide. It is.

  When miscible with water, other organic ionic compounds can also be used as salt components in the softening process of the present invention. Available compounds are exemplified in Finnish Patent No. 20031156.

  In the softening method of the present invention, stirring is performed at a temperature between 40 ° C. and 270 ° C., preferably at a temperature between 70 ° C. and 210 ° C., most preferably at a temperature between 120 ° C. and 190 ° C. it can.

  In the softening method of the present invention, it is also possible to use pressure. When utilized, the pressure is preferably below 20 bar, more preferably below 10 bar, most preferably between 2 and 9 bar.

  The agitation time can vary between 1 minute and 24 hours depending on the salt used and its concentration, the nature and concentration of the lignocellulosic material and possibly depending on the agitation temperature as well as the pressure utilized.

  In the softening method of the present invention, it is advantageous to select the aforementioned parameters in a way that the lignocellulosic material is only softened and not pulped. Therefore, substantial delignification does not occur during the softening process of the present invention. The structure of lignocellulosic material is cleaved and impregnated with an aqueous tetraalkylammonium salt solution in a manner that reduces energy and / or chemical consumption in subsequent processing steps.

  The softened lignocellulosic material can be used as a raw material for the production of paper, paperboard, fiberboard and similar industrial products.

  The present invention completes a new pulp. It can be manufactured in a rapid and energy efficient manner. The degree of delignification can be adjusted. Also, the resulting pulp is thin and of high quality consisting of long fibers. The present invention also achieves a method for softening lignocellulosic materials. The aforementioned softened, malleable material can then be further processed in a more energy efficient manner. Therefore, the present invention provides low energy consumption and such environmental conservation benefits. Also, formation of organic sulfur compounds that give off malodors can be avoided. The tetraalkylammonium salt used is a relatively cheap chemical product. And it is preferably recycled.

  The following examples illustrate the present invention without limiting the foregoing invention to the examples. In Examples 1-10, the treated lignocellulosic material was a Finnish softwood bar cut from a 20 mm long wood chip. The bar was cut parallel to a thin layer of wood to help long fibers. The original reason for cutting the bar was the limited size (ie 5 ml) of the microwave reactor.

Example 1
Treatment of softwood in 40% tetrabutylammonium hydroxide water at 170 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 40% tetrabutylammonium hydroxide aqueous solution and stirred at 170 ° C. for 5 minutes in a closed reaction tube equipped with a magnetic stirrer.
This agitation resulted in a dark brownish solution containing long fiber particles. Washing with water yielded both separate light beige fiber bundles as well as completely separate fibers.

Example 2
Treatment of softwood in 20% tetrabutylammonium hydroxide water at 170 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 20% aqueous tetrabutylammonium hydroxide and stirred in a sealed reaction tube with a magnetic stirrer at 170 ° C. for 5 minutes.
This agitation resulted in a dark brownish solution containing long fiber particles. Washing with water yielded both separate light beige fiber bundles as well as completely separate fibers. This pulp composition was slightly intact compared to that of Example 1.

Example 3
Treatment of softwood in 10% tetrabutylammonium hydroxide water at 170 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 10% tetrabutylammonium hydroxide aqueous solution and stirred at 170 ° C. for 5 minutes in a closed reaction tube equipped with a magnetic stirrer.
This agitation resulted in a dark brownish solution containing long fiber particles. Washing with water resulted in both a bundle of separated light beige fibers and an intact pulp composition compared to that of Example 2.

Example 4
Treatment of softwood in 10% tetrabutylammonium hydroxide water at 170 ° C, microwave field-30 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 10% tetrabutylammonium hydroxide aqueous solution and stirred at 170 ° C. for 30 minutes in a closed reaction tube equipped with a magnetic stirrer.
This agitation resulted in a dark brownish solution containing long fiber particles. Washing with water resulted in both separated light beige fiber bundles and a pulp composition similar to that of Example 1.

Example 5
Treatment of softwood in 40% tetrabutylammonium hydroxide water at 120 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 40% tetrabutylammonium hydroxide aqueous solution and stirred in a sealed reaction tube with a magnetic stirrer at 120 ° C. for 5 minutes.
This agitation resulted in a dark brownish solution containing long fiber particles. Washing with water yielded both separate light beige fiber bundles as well as completely separate fibers. This pulp composition was similar to that of Example 2.

Example 6
Treatment of softwood in 5% tetrabutylammonium hydroxide water at 120 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 5% tetrabutylammonium hydroxide aqueous solution and stirred in a sealed reaction tube with a magnetic stirrer at 120 ° C. for 5 minutes.
This agitation resulted in a brownish solution containing several wooden bars and long fiber particles. Washing with water resulted in a dramatically softened wooden stick and some particles separated from the stick.

Example 7
Treatment of softwood in 40% tetrabutylammonium hydroxide water at 80 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 40% tetrabutylammonium hydroxide aqueous solution and stirred in a sealed reaction tube with a magnetic stirrer at 80 ° C. for 5 minutes.
This agitation resulted in a brownish solution containing several wooden bars and long fiber particles. Washing with water resulted in a wooden bar that was dramatically softened and partially separated, and several particles that were also separated from the bar.

Example 8
Treatment of softwood in 10% tetrabutylammonium hydroxide water at 80 ° C, microwave field-30 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 10% aqueous tetrabutylammonium hydroxide and stirred in a sealed reaction tube with a magnetic stirrer at 80 ° C. for 30 minutes.
As in Example 7, this agitation resulted in a brownish solution containing several wooden bars and long fiber particles. Washing with water resulted in a wooden bar that was dramatically softened and partially separated, and several particles that were also separated from the bar.

Example 9
Treatment of softwood in 10% tetrabutylammonium hydroxide water at 70 ° C, microwave field-1 hour

About 750 mg of a softwood rod was mixed with 4.5 ml of 10% aqueous tetrabutylammonium hydroxide and stirred in a sealed reaction tube with a magnetic stirrer at 70 ° C. for 1 hour.
Here, this agitation resulted in a clear, light brownish solution containing several wooden bars. Washing with water resulted in dramatically softened and partially separated wooden sticks.

Example 10
Comparative treatment of softwood in 40% sodium hydroxide (NaOH) at 170 ° C, microwave field-5 minutes

About 750 mg of a softwood rod was mixed with 4.5 ml of 40% aqueous sodium hydroxide (NaOH) and stirred in a sealed reaction tube with a magnetic stirrer at 170 ° C. for 5 minutes.
Here, the agitation resulted in the destruction of the fibrous material while producing a part of the mucous, brownish, non-fibrous organic material.

Example 11
Comparative treatment of softwood in 40% tetrabutylammonium hydroxide water without microwave field

About 2000 mg of a softwood rod was mixed with 12 ml of 40% aqueous tetrabutylammonium hydroxide (NaOH) and stirred in a flask with a magnetic stirrer at 95 ° C. overnight.
Also here, this agitation resulted in the destruction of the fiber material while producing some of the mucous, brownish, non-fibrous organic material.

Claims (18)

  Pulp derived from lignocellulosic material stirred in an aqueous tetraalkylammonium salt solution under microwave irradiation.   The pulp according to claim 1, wherein the lignocellulosic material is a soft material or a hard material.   The tetraalkylammonium salt content in the aqueous tetraalkylammonium salt content is 1 to 75% by weight, preferably 5 to 60% by weight, and most preferably 10 to 40% by weight. 2. Pulp according to 2. The cation of the tetraalkylammonium salt has the following chemical formula

Wherein R ¹ , R ² , R ³ and R ⁴ are independently a C ₁ -C ₃₀ alkyl group, a C ₃ -C ₈ carbocyclic group or a C ₃ -C ₈ heterocyclic group. Indicated,
Anion is halogen tetraalkylammonium salts, pseudohalogen, perchlorate, pulp according to any one of claims 1 to 3, characterized in that the C ₁ -C ₆ carboxylate or hydroxide . The pulp according to claim 4, wherein R ¹ , R ² , R ³ and R ⁴ are each independently a C ₄ alkyl group, and the anion of the tetraalkylammonium salt is a hydroxide.   5. Stirring is performed at a temperature of 40 ° C. to 270 ° C., preferably at a temperature of 70 ° C. to 210 ° C., and most preferably at a temperature of 120 ° C. to 190 ° C. The pulp according to item 1.   A process for pulping a lignocellulosic material, characterized in that the lignocellulosic material is stirred in an aqueous tetraalkylammonium salt solution under microwave irradiation for partial or complete delignification.   The method according to claim 7, wherein the lignocellulosic material is a soft or hard material.   The content of the tetraalkylammonium salt in the tetraalkylammonium salt aqueous solution is 1 to 75% by mass, preferably 5 to 60% by mass, and most preferably 10 to 40% by mass, 9. The method according to 8. The cation of the tetraalkylammonium salt has the following chemical formula

Wherein R ¹ , R ² , R ³ and R ⁴ are independently a C ₁ -C ₃₀ alkyl group, a C ₃ -C ₈ carbocyclic group or a C ₃ -C ₈ heterocyclic group. Indicated,
The method according to claim 7, wherein the anion of the tetraalkylammonium salt is halogen, pseudohalogen, perchlorate, C ₁ -C ₆ carboxylate or hydroxide. . The method according to claim 10, wherein R ¹ , R ² , R ³ and R ⁴ are independently a C ₄ alkyl group, and the anion of the tetraalkylammonium salt is a hydroxide.   11. Stirring is performed at a temperature of 40 ° C. to 270 ° C., preferably at a temperature of 70 ° C. to 210 ° C., and most preferably at a temperature of 120 ° C. to 190 ° C. 2. The method according to item 1.   A method for softening a lignocellulose material, comprising stirring the lignocellulose material in a tetraalkylammonium salt aqueous solution under microwave irradiation.   The method according to claim 13, wherein the lignocellulosic material is a soft or hard material.   The tetraalkylammonium salt content in the aqueous tetraalkylammonium salt content is 1 to 75% by weight, preferably 5 to 60% by weight, and most preferably 10 to 40% by weight. 14. The method according to 14. The cation of the tetraalkylammonium salt has the following chemical formula

Wherein R ¹ , R ² , R ³ and R ⁴ are independently a C ₁ -C ₃₀ alkyl group, a C ₃ -C ₈ carbocyclic group or a C ₃ -C ₈ heterocyclic group. Indicated,
Anion is halogen tetraalkylammonium salts, pseudohalogen, perchlorate, A process according to any one of claims 13 to 15, characterized in that the C ₁ -C ₆ carboxylate or hydroxide . The method according to claim 16, wherein R ¹ , R ² , R ³ and R ⁴ are independently a C ₄ alkyl group, and the anion of the tetraalkylammonium salt is a hydroxide.   Stirring is performed at a temperature between 40 ° C and 270 ° C, preferably at a temperature between 70 ° C and 210 ° C, and most preferably at a temperature between 120 ° C and 190 ° C. The method according to any one of 13 to 16.