JP7270180B2 - Method for producing chemical pulp and pulp cooking aid - Google Patents

Description

The present disclosure relates to a method for making chemical pulp, a method for cooking lignocellulosic material and a pulp cooking aid.

Chemical pulping, that is, methods of chemically treating lignocellulosic material to produce pulp, include alkaline and sulfite cooking methods. Alkaline cooking methods in the present disclosure include a wide variety of kraft cooking methods, soda cooking methods, sulfite cooking methods, organosolv cooking methods, and the like. In addition, the sulfite cooking method (sulfite method) in the present disclosure is a general term for various sulfite methods including the alkaline sulfite method, the neutral sulfite method, the acid sulfite method, and the bisulfite method.
Hydroanthraquinones such as dihydroanthraquinone and tetrahydroanthraquinone are used as cooking aids in the production of pulp by cooking lignocellulosic materials in order to improve the pulp yield and the cooking rate. (For example, Patent Document 1). Also, polyoxyalkylene alkyl ether carboxylate is known as a resin removing agent for the cooking process (Patent Document 2).

JP-A-54-82401 Japanese Patent Publication No. 53-28522

However, in recent years, the carcinogenicity of anthraquinone has been pointed out. For example, the European Food Safety Authority (EFSA) issued an opinion in 2012 that anthraquinones cannot be ruled out as carcinogenic. In response, the German Federal Institute for Risk Assessment (BfR) announced in 2013 that anthraquinone would be removed from the list of substances permitted for use in food packaging paper. There is a tendency to refrain from
Moreover, there is a problem that even if the polyoxyalkylene alkyl ether carboxylate is added, the pulp yield and pulp quality cannot be sufficiently improved. Furthermore, when the kappa number obtained in the cooking process is high, there is a problem that a large amount of bleaching agents (oxygen, chlorine dioxide, chlorine, hypochlorous acid, hydrogen peroxide, sodium hydroxide, ozone, etc.) is required in the bleaching process. be.
Therefore, there is a demand for a new cooking aid capable of improving the pulp yield and lowering the kappa number in place of the conventional methods.

In one or more embodiments, the present disclosure provides a method for producing chemical pulp, a cooking method, and a pulp cooking aid and pulp cooking composition used therefor that can improve yield and reduce kappa number. do.

The present disclosure, in one aspect, relates to a method for producing chemical pulp that includes alkaline or sulfite cooking a lignocellulosic material in a chemical solution containing a radical scavenger and a nonionic surfactant.

The present disclosure relates, in one aspect, to a method for alkaline or sulfite cooking of lignocellulosic material comprising cooking the lignocellulosic material in a chemical solution containing a radical scavenger and a nonionic surfactant.

The present disclosure, in one aspect, relates to a pulp cooking aid containing a radical scavenger and a nonionic surfactant.

The present disclosure, in one aspect, relates to a pulp cooking composition comprising a first component containing a radical scavenger and a second component containing a nonionic surfactant.

INDUSTRIAL APPLICABILITY According to the present disclosure, in one or more embodiments, it is possible to provide a chemical pulp manufacturing method, a cooking method, a pulp cooking aid, and a pulp cooking composition that can improve pulp yield and reduce kappa number.

1] is a block diagram showing an example of the flow of a chemical pulp production system. [FIG. FIG. 2 shows a photograph of uncooked fibers that were not flat screen screened in Example 1. FIG.

The present disclosure is based on the finding that cooking in the presence of a radical scavenger and a nonionic surfactant promotes delignification and achieves both improved screen yield and reduced kappa number.

Although the reason why the above effects are obtained by cooking in the presence of a radical scavenger and a nonionic surfactant is not clear, it is presumed as follows.
The radical scavenger itself and hydrogen in the cooking liquor react with radicals derived from lignin, cellulose, etc., which are liberated or fragmented by cooking. This reaction can suppress the radical coupling reaction between lignins and the radical coupling reaction between lignin and cellulose. lignocellulose conversion can be suppressed, thereby improving the screening yield (pulp yield) than before.
In addition, nonionic surfactants act on hydrophobic substances such as lignin on the surface of cellulose, making it easier to remove hydrophobic substances from cellulose. easier access to the drug. As a result, the cellulose becomes easier to loosen, and the nonionic surfactant acts more easily on the hydrophobic substance, making it easier to remove the hydrophobic substance from the cellulose. becomes lower.
As a result, it is considered that both an improvement in screening yield (pulp yield) and a decrease in kappa number can be realized. However, the present disclosure is not limited to these mechanisms.

In the present disclosure, the “screening yield (pulp yield)” refers to the dry weight of the pulp (screening pulp) after removing uncooked fibers such as knot residue from the unbleached pulp after cooking. (Lignocellulosic material) Refers to the percentage of the total absolute dry weight.
In the present disclosure, "absolute dry weight" refers to the weight after drying at 105°C for one day.
In the present disclosure, the “kappa number” refers to the kappa number obtained by testing the above screened pulp according to JIS P 8211 (pulp-kappa number test method).

In the present disclosure, "chemical pulp" is pulp obtained by chemically treating and delignifying lignocellulosic material. Chemical pulps, in one or more embodiments, include sulfite pulp, dissolved sulfite pulp, alkaline pulp, kraft pulp, dissolved kraft pulp, or the like.

Methods for producing chemical pulp include alkali cooking and sulfite cooking. As the alkaline cooking method, in one or more embodiments, a strong alkaline aqueous solution such as an aqueous solution of sodium hydroxide or a mixed solution of sodium hydroxide and sodium sulfide is used as a cooking chemical solution, and in the cooking solution, for example, A method of cooking a cellulose raw material at 140 to 180° C. to obtain a pulp can be mentioned. Alkaline digestion, in one or more embodiments, includes various methods such as kraft digestion, soda digestion, sulfite digestion, or organosolv digestion. In one or more embodiments, the sulfite cooking method includes various sulfite methods such as an alkaline sulfite method, a neutral sulfite method, an acid sulfite method, and a bisulfite method.

In the present disclosure, the term “cooking” means subjecting a wood or non-wood lignocellulose material to high-temperature, high-pressure treatment using chemicals to dissolve or remove non-fiber materials such as lignin from the lignocellulose material to produce cellulose or the like. Separation of fibrin. Cooking in the present disclosure includes alkaline cooking or sulfite cooking. Cooking, in one or more embodiments, can be carried out by heating the lignocellulosic material and an alkaline solution (cooking liquor) containing a radical scavenger in a kettle. “Cooking” in the present disclosure includes not only cooking under high temperature and high pressure using a digester for fiberization (pulping), but also oxygen cooking for delignification (e.g., oxygen digester in oxygen delignification process ( cooking performed in an _O2 reactor)). High temperature treatment in the present disclosure includes heating to 80° C. or higher in one or more embodiments. Cooking in the present disclosure includes, in one or more embodiments, heating the chemical solution containing the radical scavenger or the alkaline solution to a temperature of 80°C to 200°C. In one or more embodiments, high-pressure treatment in the present disclosure includes applying pressure to 0.2 MPa or more, preferably 0.3 MPa or more, 1.0 MPa or more, or 3.0 MPa or less, It is preferably 2.0 MPa or less.

In the present disclosure, "lignocellulose material" may be various types of wood such as wood chips, or non-wood such as straw. Wood, in one or more embodiments, includes softwood (N material) chips and hardwood (L material) chips. Conifers, in one or more embodiments, include larch, red pine, cedar, and the like. Broadleaf trees, in one or more embodiments, include eucalyptus, acacia, and the like. The lignocellulosic material, in one or more embodiments, may be a single type of lignocellulosic material or a mixture of two or more types of lignocellulosic material. Lignocellulosic materials in the present disclosure can include pulp slurries (eg, unbleached or unbleached pulp, etc.) discharged from the digester (digestion process), as well as the wood chips and the like described above.

[Radical Scavenger]
In the present disclosure, the term “radical scavenger” refers to a compound that binds or can bind to radical species generated during cooking, or a compound that suppresses or can suppress a polymerization reaction caused by the radical species generated. Radical scavengers of the present disclosure can also be referred to as free radical scavengers in one or more embodiments.

Examples of radical scavengers include, in one or more embodiments, tetramethylpiperidineoxyl-based radical scavengers, phenol-based radical scavengers, amine-based radical scavengers, quinone-based radical scavengers, and the like.

Tetramethylpiperidineoxyl-based radical scavengers include, in one or more embodiments, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-TEMPO), 2,2,6, 6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-cyano-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-benzoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6, 6-tetramethylpiperidine-1-oxyl, 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl, or bis-(2,2,6,6-tetramethylpiperidine-1-oxyl) - Sebacate and the like. As the tetramethylpiperidineoxyl-based radical scavenger, H-TEMPO is preferred in one or more embodiments.

Phenolic radical scavengers include, in one or more embodiments, 2-methylphenol, 2-ethylphenol, 2-propylphenol, 2-methoxyphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-tert-butylcatechol (TBC) and the like. As the phenolic radical scavenger, TBC is preferred in one or more embodiments.

As the amine-based radical scavenger, in one or more embodiments, N,N'-di-sec-butyl-1,4-phenylenediamine (PDA), N,N'-bis(1,4-dimethylpentyl )-1,4-phenylenediamine, N-(1,4-dimethylpentyl)-N′-phenyl-1,4-phenylenediamine, N-phenyl-N′-(1,3-dimethylbutyl)-1, 4-phenylenediamine, N-phenyl-N'-isopropyl-1,4-phenylenediamine, N,N'-di-phenyl-1,4-phenylenediamine or N,N'-di-2-naphthyl-1 ,4-phenylenediamine and other phenylenediamine radical scavengers, N,N-diethylhydroxylamine (DEHA) or N,N-dimethylhydroxylamine and other hydroxylamine radical scavengers, tributylamine, diphenylamine, phenothiazine, or phenyl -α-naphthylamine and the like.

In one or more embodiments, the quinone-based radical scavenger includes hydroquinone, benzoquinone, methoquinone, ethylhydroquinone, propylhydroquinone, butylhydroquinone, pentylhydroquinone, hexylhydroquinone, tert-butylhydroquinone, hydroxyhydroquinone, naphthoquinone, and the like. be done.

[Nonionic surfactant]
Nonionic surfactants in the present disclosure include, in one or more embodiments, polyoxyalkylene alkylamines, polyoxyalkylene alkyl ethers, polyoxyalkylene fatty acid esters, sucrose fatty acid esters, polyoxyalkylene alkylphenyl ethers, poly Oxyalkylenepolyoxypropylenealkylamines, ethylene oxide adducts of sorbitan fatty acid esters, polyoxyalkylenealkylalkylenediamines, and the like can be mentioned. Alkylene oxides in nonionic surfactants include, in one or more embodiments, ethylene oxide and propylene oxide and combinations thereof. As nonionic surfactants, in one or more embodiments, polyoxyalkylene alkylamines and polyoxyalkylene alkyl ethers are preferred, and polyoxyethylene alkylamines and polyoxyethylene alkyl ethers are more preferred.

The number of moles of alkylene oxide (AO) added to the polyoxyalkylenealkylamine is, in one or more embodiments, 5 or more, 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more, or 60 or less, 55 or less or 50 or less. In one or more embodiments, the lower limit of the number of carbon atoms in the alkyl group in the polyoxyalkylenealkylamine is 10 or more, 11 or more, 12 or more, or 18 or more. The upper limit of the number of carbon atoms in the alkyl group in the polyoxyethylenealkylamine is 60 or less, 55 or less, 50 or less, 45 or less, or 40 or less in one or more embodiments that are not particularly limited.

The number of added moles of AO in the polyoxyalkylene alkyl ether is, in one or more embodiments, 5 or more or 10 or more, or 55 or less or 50 or less. The number of moles of EO added to the polyoxyethylene alkyl ether is 10 or more, 11 or more, 12 or more, or 18 or more in one or more embodiments. The upper limit of the number of carbon atoms in the alkyl group in the polyoxyethylene alkyl ether is 60 or less, 55 or less, 50 or less, 45 or less, or 40 or less in one or more embodiments that are not particularly limited.

In one or more embodiments, the HLB of the nonionic surfactant is 6 or more, 8 or more, 10 or more, 12 or more, 14 or more, or 16 or more, or 19.5 or less, 18.5 or less, or 18 or less. is. In the present disclosure, “HLB (hydrophilic lipophilic balance)” can be calculated using the Griffin formula in one or more embodiments. As HLB, the value described in the catalog of the surfactant manufacturer can also be used.

In one or more embodiments, the nonionic surfactant has a molecular weight of 200 or more, 500 or more, or 1000 or more, or 5000 or less, 4000 or less, or 3000 or less.

[Method for producing chemical pulp]
In one aspect, the present disclosure is a chemical pulp manufacturing method (chemical pulp of the present disclosure) comprising subjecting a lignocellulose material to alkaline digestion or sulfite digestion in a chemical solution containing a radical scavenger and a nonionic surfactant. manufacturing method). According to the chemical pulp production method of the present disclosure, since the cooking is performed in the presence of a radical scavenger and a nonionic surfactant, in one or more embodiments, a low kappa number pulp can be produced at a high pulp yield. can be manufactured in According to the chemical pulp production method of the present disclosure, in one or more embodiments, the digestion is performed in a chemical solution containing a radical scavenger and a nonionic surfactant, so that the cellulose is more easily loosened, and Since the hydrophobic substances are more easily removed from the cellulose, it is possible to obtain a better pulp yield improvement and kappa number lowering effect than when it is used alone.

In one or more embodiments, the chemical solution used for cooking in the chemical pulp manufacturing method of the present disclosure contains at least the pulp cooking aid of the present disclosure, and further contains the chemical solution (cooking liquor) used for alkaline cooking or sulfite cooking. sell. As a chemical solution (cooking liquor) used for alkaline cooking or sulfite cooking, in one or more embodiments, in the cooking process in the production of chemical pulp such as sulfite pulp, dissolved sulfite pulp, soda pulp, kraft pulp, and dissolved kraft pulp Chemical solutions (cooking liquor) used, chemical solutions (treatment liquid) used in the oxygen delignification step, and the like.

In one or a plurality of embodiments, the chemical liquid (digesting liquor) used for alkaline cooking includes an alkaline solution (digesting liquor) and the like. The alkaline solution (cooking liquor), in one or more embodiments, contains sodium sulfide (Na ₂ S) and sodium hydroxide (NaOH), preferably sodium sulfide and sodium hydroxide as main components. . The sulfidity in alkaline (cooking liquor) is in one or more embodiments from 10% to 35%, preferably from 27% to 30%. The alkali addition amount (active alkali addition rate (AA)) is in one or more embodiments from 5% to 35%, preferably from 13% to 30%. Sulfidity is represented by (Na ₂ S)/(NaOH+Na ₂ S)×100. Active alkali is represented by converting NaOH concentration + _Na2S concentration into _Na2O .

In one or a plurality of embodiments, a chemical solution (digesting liquor) used for sulfite cooking includes a sulfite solution, a hydrogen sulfite solution (bisulfite solution), or the like.

In one or more embodiments, the chemical solution (treatment liquid) used in the oxygen delignification step includes an alkaline solution (treatment liquid) used in the oxygen delignification step. The alkaline solution, in one or more embodiments, includes an alkaline agent such as sodium hydroxide or potassium hydroxide. The pH of the alkaline solution is, in one or more embodiments, 11 or higher or 12 or higher, or 14 or lower or 13.5 or lower.

The content of the radical scavenger and the nonionic surfactant in the chemical used for digestion can be appropriately determined according to the amount (eg, absolute dry weight) of the lignocellulose material to be digested in one or more embodiments. In one or more embodiments, the content of the radical scavenger and the nonionic surfactant in the chemical solution used for digestion may be constant, or may be increased or decreased according to the concentration of the alkaline agent in the chemical solution. good too. In one or more embodiments, the production method of the present disclosure includes increasing or decreasing the content of the radical scavenger and solvent nonionic surfactant in the chemical solution according to the concentration of the alkaline agent in the chemical solution. You can

In one or more embodiments, the content of the radical scavenger in the chemical solution is 0.0005% to 5% by weight, preferably 0.001% to 5% by weight, relative to the absolute dry weight of the lignocellulose material. 2% by weight, more preferably 0.005% to 1% by weight.
In one or more embodiments, the content of the nonionic surfactant in the chemical solution is 0.0005% to 5% by weight, preferably 0.001% by weight, relative to the absolute dry weight of the lignocellulose material. % to 2% by weight, more preferably 0.005% to 1% by weight.
In one or more embodiments, the total content of the radical scavenger and nonionic surfactant in the chemical solution is 0.0005% to 5% by weight relative to the absolute dry weight of the lignocellulose material, It is preferably 0.001% to 2% by weight, more preferably 0.005% to 1% by weight.

The ratio (weight ratio) of the nonionic surfactant to the radical scavenger in the chemical used for cooking is 0.01-100, preferably 0.1-10 in one or more embodiments.

The production method of the present disclosure, in one or more embodiments, may include the step of adding a radical scavenger and a nonionic surfactant. Addition of the radical scavenger and the nonionic surfactant, in one or more embodiments, should be carried out so that the content of the radical scavenger and the nonionic surfactant in the chemical solution to be digested is the above content. good. The amount of the radical scavenger and the nonionic surfactant to be added is, in one or more embodiments, appropriately depending on the amount of the lignocellulose material or pulp to be digested and the concentration of the alkaline agent such as sodium hydroxide in the chemical solution. can be determined, and the amount added may be constant, or may be increased or decreased depending on the situation. In one or more embodiments, the production method of the present disclosure may include increasing or decreasing the amount of the radical scavenger and the nonionic surfactant added according to the concentration of the alkaline agent in the chemical solution.

Radical scavengers and nonionic surfactants are not particularly limited as long as they are added in a chemical solution containing them so that the lignocellulose material exhibits the above effects in digestion. Moreover, in one or more embodiments, the radical scavenger and the nonionic surfactant may be added in a mixed state, or may be added separately. When added separately, the order of addition of the radical scavenger and nonionic surfactant is not particularly limited, and in one or more embodiments, after adding the radical scavenger, even if the nonionic surfactant is added Alternatively, the radical scavenger may be added after adding the nonionic surfactant, or the radical scavenger and nonionic surfactant may be added at the same time.

In one or a plurality of embodiments, the radical scavenger and the nonionic surfactant are added at least one location from the raw material chip supply step prior to the cooking step to the cooking step of digesting the lignocellulose material with alkali or sulfite. mentioned. Radical scavengers and nonionic surfactants, in one or more embodiments, may be added to the digester where cooking takes place, or from the standpoint of improving yield, the raw material that feeds the raw chips to the digester. It is preferably added in any of the chip feeding processes. In one or a plurality of embodiments, addition points in the raw material chip supply step include a chip bin (13 in FIG. 1), a steaming vessel (14 in FIG. 1), a metal trap, a chip chute, a high-pressure feeder, and the like. Therefore, the manufacturing method of the present disclosure may include mixing a radical scavenger and a nonionic surfactant with raw material chips.
It may also be added to the injection circulation line of the cooking liquor (white liquor and black liquor), or to the oxygen digester in the delignification step after cooking in the digester. In one or more embodiments, the radical scavenger and nonionic surfactant may be added at once, or may be added in portions.

In one or more embodiments of the production method of the present disclosure, the concentration of the radical scavenger with respect to the absolute dry weight of the raw material lignocellulose material is 0.0005% by weight to 5% by weight. It may comprise adding a radical scavenger to the (cooking liquor), preferably 0.001% to 2% by weight, more preferably 0.005% to 1% by weight.
In one or more embodiments of the production method of the present disclosure, cooking is performed so that the concentration of the nonionic surfactant with respect to the absolute dry weight of the lignocellulose material as a raw material is 0.0005% to 5% by weight. It may comprise adding a radical scavenger to the chemical liquor (cooking liquor) to be carried out, preferably 0.001% to 2% by weight, more preferably 0.005% to 1% by weight.
In one or more embodiments of the production method of the present disclosure, the total content of the radical scavenger and nonionic surfactant in the chemical liquid (cooking liquid) for cooking is It may include adding a radical scavenger and a nonionic surfactant to the chemical solution (cooking liquor) for cooking so that the content is 0.0005% to 5% by weight, preferably 0.001% by weight. % to 2% by weight, more preferably 0.005% to 1% by weight.

In one or more embodiments of the production method of the present disclosure, the ratio (weight ratio) of the nonionic surfactant to the radical scavenger in the chemical liquid used for cooking is 0.01 to 0.01 in one or more embodiments. 100, may include adding a radical scavenger to the chemical solution.
In one or more embodiments of the production method of the present disclosure, the ratio (weight ratio) of the radical scavenger to the nonionic surfactant in the chemical solution used for cooking is 0.01 to 0.01 in one or more embodiments. It may include adding a nonionic surfactant to the chemical solution so that it becomes 100.

Since the production method of the present disclosure can further improve the yield of pulp and further reduce the kappa number of the obtained pulp, in one or more embodiments, the chemical solution (cooking liquor) for cooking further contains a solvent. You can Therefore, in one or more embodiments, the production method of the present disclosure includes alkaline digestion or sulfite digestion of a lignocellulose material in a chemical solution containing a radical scavenger, a nonionic surfactant, and a solvent. good too. In addition, in one or more embodiments, the production method of the present disclosure may include adding a solvent to the chemical solution (cooking liquor) for cooking. The partial kappa number reduction effect of the solvent can be applied to the entire lignocellulose material by using it in combination with the radical scavenger, and a better kappa number reduction effect can be obtained than when it is used alone. A solvent may be mixed with a radical scavenger and added in one or more embodiments. Solvents that can be used are as described below.

FIG. 1 shows an example of the flow of the chemical pulp manufacturing method. The flow of FIG. 1 includes a step of supplying raw material chips of lignocellulose material, a cooking step, and an oxygen delignification step.
(Raw material chip supply process)
Chips 11 of lignocellulose material chipped by a chipper (not shown) are stored in a chip silo 12 . After the chips stored in the chip silo 12 are selected by a chip screen (not shown) and sent to the chip bin 13 , the gas phase inside the chips is replaced with water vapor in the steaming vessel 14 .
(Cooking process)
The chips whose permeability has been enhanced in the steaming vessel 14 are introduced with an alkaline cooking liquid in the impregnation tower 15 to promote the permeation of the cooking liquid into the interior of the chips. Thereafter, in the digester 16, wood chips, which are pulp materials, are mixed with a solution containing at least a radical scavenger, a nonionic surfactant, sodium hydroxide, etc., and steamed under pressure to dissolve the non-fiber components. Pulp slurry in which black liquor and pulp are mixed is discharged. Permeate tower 15 may also optionally be used as a prehydrolysis vessel (PHV) tower for prehydrolysis with acid.
(Oxygen delignification step)
The pulp slurry discharged from the digester 16 is washed in a black liquor washing tower 17, passed through a screen 18, a decker 19 and an unbleached high-concentration storage tower 20, and then introduced into an oxygen digester 21. Further delignification takes place in the oxygen digester 21 before being transferred to the bleaching step (not shown).

The heating temperature during cooking is, in one or more embodiments, 80°C to 200°C, preferably 140°C to 180°C. In one or more embodiments of the production method of the present disclosure, the lignocellulose material is heated at 80 ° C. to 200 ° C. in a chemical solution that is an alkaline solution containing a radical scavenger and a nonionic surfactant. including a cooking step.

The heating time during digestion is, in one or more embodiments, 30 minutes to 400 minutes, preferably 50 minutes to 300 minutes.

The production method of the present disclosure may include pre-treating the lignocellulosic material prior to the cooking as described above. In one or more embodiments, the pretreatment includes hydrothermal treatment (prehydrolysis treatment) and the like. Hydrothermal treatment, in one or more embodiments, can be performed by treating the chipped lignocellulose material with hot water or steam.

[Cooking method]
In one aspect of the present disclosure, a method for alkaline or sulfite cooking of a lignocellulose material (cooking method of the present disclosure), which comprises cooking a lignocellulose material in a chemical solution containing a radical scavenger and a nonionic surfactant. Regarding. According to the cooking method of the present disclosure, in one or more embodiments, improved pulp yield after cooking and reduced kappa number after cooking can be achieved. In the cooking method of the present disclosure, cooking can be performed in the same manner as in the production method of the present disclosure.

[Pulp cooking aid]
The present disclosure, in one aspect, relates to a pulp cooking aid (pulp cooking aid of the disclosure) containing a radical scavenger and a nonionic surfactant. According to the pulp cooking aid of the present disclosure, in one or more embodiments, improved pulp yield after cooking and reduced kappa number after cooking can be realized. According to the pulp cooking aid of the present disclosure, in one or more embodiments, the combined use of a radical scavenger and a nonionic surfactant makes it easier to loosen cellulose and remove more hydrophobic substances. Therefore, it is possible to obtain a better pulp yield improvement and kappa number lowering effect than when it is used alone.

The content of the radical scavenger in the cooking aid of the present disclosure is, in one or more embodiments, 1-50% by weight, preferably 5-40% by weight.

The nonionic surfactant content in the cooking aid of the present disclosure is, in one or more embodiments, 1 to 50% by weight, preferably 5 to 40% by weight. The content of the nonionic surfactant may be determined according to the content of the radical scavenger in one or more embodiments. The blending ratio of the nonionic surfactant to the radical scavenger (100 parts by weight) is, in one or more embodiments, 1 to 50% by weight, preferably 5 to 40% by weight.

The pulp cooking aid of the present disclosure can contain a radical scavenger at a high concentration and can be made into a one-component formulation with excellent long-term storage stability, and further contains a solvent. good too.

Solvents include hydrophilic organic solvents in one or more embodiments. Solvents include, in one or more embodiments, glycol-based solvents, glycol ether-based solvents, alcohol-based solvents, amine/amide-based solvents, and the like. Solvents may be used singly or in combination of two or more in one or more embodiments.

Glycol-based solvents include, in one or more embodiments, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, or polypropylene glycol. As the glycol-based solvent, ethylene glycol or the like is preferable in one or more embodiments.

As the glycol ether solvent, in one or more embodiments, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, Diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether propionate, propylene glycol monobutyl ether, 3-methoxy-3-methyl-1-butanol, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and the like. As the glycol ether-based solvent, in one or more embodiments, ethylene glycol monophenyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, or the like is preferable.

As alcohol solvents, in one or more embodiments, methanol, ethanol, n-propanol, iso-propanol, n-butanol, tert-butanol, 1,4-butanediol, 1,5-pentanediol, benzyl alcohol , or 2-ethyl-1-hexanol.

As the amine/amide solvent, in one or more embodiments, N,N-dimethylformamide, N-methylpyrrolidone, hexamethylphosphoric acid triamide, 1,3-dipropylimidazolidinone, 1,3-dimethylimidazon lysinone tetramethylurea, N,N-dimethylacetamide dimethylsulfonium, monoethanolamine, diethanolamine, triethanolamine, ditripropanolamine, tripropanolamine, triisopropanolamine and the like.

As the solvent, in one or a plurality of embodiments, a glycol ether solvent and a glycol solvent are preferable because they can improve the pulp yield and decrease the kappa value of the obtained pulp.

The content of solvent in the cooking aid of the present disclosure is, in one or more embodiments, 1-80% by weight, preferably 5-40% by weight. The content of the solvent may be determined according to the content of the radical scavenger in one or more embodiments. The blending ratio of the solvent to the radical scavenger (100 parts by weight) is, in one or more embodiments, 1 to 500 parts by weight, preferably 25 to 200 parts by weight.

The cooking aids of the present disclosure may contain water in one or more embodiments. The water content in the cooking aids of the present disclosure, in one or more embodiments, can be determined according to the surfactant content. The mixing ratio of water to surfactant (100 parts by weight) is, in one or more embodiments, 100 to 2000 parts by weight, preferably 200 to 1200 parts by weight.

The cooking aids of the present disclosure, in one or more embodiments, may further include antifoaming agents, other additives, and the like.

The cooking aid of the present disclosure, in one or more embodiments, can be produced by mixing a radical scavenger and a nonionic surfactant, and if necessary water, solvent, antifoaming agent or other can be produced by mixing the additives together, preferably by uniformly mixing them.

[Pulp cooking composition]
In one aspect, the present disclosure relates to a pulp cooking composition comprising a first component containing a radical scavenger and a second component containing a nonionic surfactant (the pulp cooking composition of the present disclosure). According to the pulp cooking composition of the present disclosure, in one or more embodiments, it is possible to achieve an improvement in the pulp yield after cooking and a decrease in the kappa number after cooking. According to the pulp cooking composition of the present disclosure, in one or more embodiments, the combined use of a radical scavenger and a nonionic surfactant makes it easier for cellulose to loosen, and makes it easier for hydrophobic substances to be removed. Therefore, it is possible to obtain a better pulp yield improvement and kappa number lowering effect than when it is used alone.

In one or more embodiments, the first component containing the radical scavenger and the second component containing the nonionic surfactant may be enclosed in separate containers or may be enclosed in the same container. good too.

The first component containing a radical scavenger can contain a high concentration of the radical scavenger and can improve long-term storage stability, so in one or more embodiments, it further contains a solvent. may be The type and content of the solvent are the same as for the cooking aid of the present disclosure above.

The present disclosure may relate to one or more embodiments of;
[1] A method for producing chemical pulp, comprising subjecting a lignocellulose material to alkaline digestion or sulfite digestion in a chemical solution containing a radical scavenger and a nonionic surfactant.
[2] The production method according to [1], wherein the nonionic surfactant is selected from the group consisting of polyoxyalkylenealkylamines and polyoxyalkylenealkylethers.
[3] The radical scavenger is selected from the group consisting of tetramethylpiperidineoxyl radical scavengers, phenol radical scavengers, amine radical scavengers and quinone radical scavengers [1] or [2] The manufacturing method described in .
[4] The production method according to any one of [1] to [3], wherein the cooking includes heating the chemical solution to a temperature of 80°C to 200°C.
[5] A method of digesting a lignocellulose material with alkali or sulfite, which comprises digesting the lignocellulose material in a chemical solution containing a radical scavenger and a nonionic surfactant.
[6] A pulp cooking aid containing a radical scavenger and a nonionic surfactant.
[7] A pulp cooking composition comprising a first component containing a radical scavenger and a second component containing a nonionic surfactant.

The present disclosure will be further described below using examples and reference examples. However, the present disclosure should not be construed as being limited to the following examples.

[Radical Scavenger]
H-TEMPO: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl TBC: 4-tert-butylcatechol [surfactant]

[Preparation example]
Digesting aids A to H were prepared by mixing a radical scavenger and a surfactant shown in Table 2 below at a ratio of 1:1 (weight ratio). Specifically, the cooking aids A to G are prepared by mixing an H-TEMPO aqueous solution with surfactants shown in Table 2 below so that the mixing ratio of the surfactant to 100 parts by weight of H-TEMPO is 100 parts by weight. was prepared by Cooking aid H was prepared by mixing TBC and NIS-1 so that the blending ratio of NIS-1 to 100 parts by weight of TBC was 100 parts by weight. The content of active ingredients (total of radical scavenger and surfactant) contained in cooking aids A to H is 15% by weight, and the mixing ratio of surfactant and water (water/surfactant) is 10/1.

[Example 1]
A 100 ml metal container is filled with 40 g (absolute dry weight) of red pine chips, and then the following cooking liquor (20% active alkali, 29% sulfidity) is added to the liquid ratio (ratio of cooking liquor weight to absolute dry weight of chips: liquor/ Chips) 4.2 was added, and the chemicals shown in Table 3 were added to the chips in an amount of 0.5% by weight relative to the absolute dry weight of the chips, and then cooking was carried out under the following cooking conditions. The screening yield and kappa number of the obtained unbleached pulp were measured according to the following methods. Table 3 shows the results.
In Reference Examples, H-TEMPO, NIS-1 or NIS-2 was added as a chemical agent to 0.5% by weight relative to the absolute dry weight of the chip, and the same treatment and measurement were performed. Blanks were treated and measured in the same way without the addition of drugs. These results are shown in Table 3.
<Cooking liquor>
Composition: 20% active alkali, 29% sulfidity
Active alkali: value obtained by converting NaOH concentration + Na ₂ S concentration into Na ₂ O <cooking conditions>
Apparatus: pressure vessel, nitrogen substitution Heating conditions: 160°C, 1.6 MPa, 3 hours

[Selection yield]
The obtained unbleached pulp was placed in a cloth bag, washed thoroughly with tap water, and then undigested fibers were removed using a flat screen (manufactured by Kumagai Riki Kogyo Co., Ltd.). . The screen pulp was dried at 105° C. for 3 hours to obtain the oven dry weight of the screen pulp. The screened yield was obtained by dividing the bone dry weight of the screened pulp by the bone dry weight of the chips before digestion and expressed in weight %. Also shown in FIG. 2 is a photograph of the uncooked fibers that were not screened on the flat screen.

[Kappa number]
The kappa number of the screened pulp was measured by the method of JIS P 8211.

As shown in Table 3, by cooking with a cooking liquor to which cooking aids A to G containing H-TEMPO and a nonionic surfactant were added, compared with the blank, the clarification yield was improved. And a decrease in the kappa number was confirmed. again. The combined use of H-TEMPO and nonionic surfactants (use of cooking aids A to G) to improve the selective yield and reduce the kappa number was obtained by using H-TEMPO and nonionic surfactants alone. Higher compared to when added cooking liquor is used, especially when used in combination with cooking aid F NIS-6 (polyoxyethylene stearylamine, EO addition moles 45, HLB 17.6). An improvement in yield and a decrease in kappa number were confirmed. From the test results of cooking aids B to F, it can be seen that the higher the number of moles of EO added, the better results tend to be obtained.
Further, the same procedure as in Example 1-1 was performed except that instead of cooking aid B, cooking aid H (TBC/NIS-1) was used. As a result, as in the case of H-TEMPO, by using TBC in combination with a nonionic surfactant, it was confirmed that the selective yield was improved and the kappa number was lowered.

In addition, as shown in FIG. 2, even though the cooking liquor and cooking conditions were the same except that the chemicals added to the cooking liquor were different, cooking aid A containing H-TEMPO and a nonionic surfactant was used. Or when cooking with a cooking liquor with the addition of B (Example 1-1 or 1-2), when using a cooking liquor with the addition of blank and H-TEMPO and nonionic surfactant alone (Blank, reference Compared to Examples 1-1 to 1-3), it was confirmed that the amount of undigested fibers remaining on the flat screen was significantly smaller, and that the undigested fibers were loosened more finely. That is, by adding H-TEMPO (radical scavenger) and a nonionic surfactant to the cooking liquor, wood chips can be uniformly and sufficiently cooked to be sufficiently converted into pulp fiber, and this sufficient pulp fiber can be obtained. This makes it easier for the nonionic surfactant to act on the hydrophobic substances of the pulp, and it can be said that both an improvement in the screening yield and a decrease in the kappa number have been achieved.

As a comparative example, instead of cooking aid A, cooking aid I or J shown in Table 4 below (combined use of radical scavenger and cationic surfactant or anionic surfactant) was used. It was carried out in the same manner as in Example 1-1. As a result, the selection yield and kappa number by the combined use of the radical scavenger and the cationic surfactant or the anionic surfactant were comparable to those by using each drug alone. That is, in the combined use with a cationic surfactant or an anionic surfactant, no improvement in the effect due to combined use with a radical scavenger seen in the combined use with a nonionic surfactant could be confirmed.

[Example 2]
In the same manner as in Example 1, except that 35 g (absolute dry weight) of acacia chips and the chemicals shown in Table 5 below were used instead of red pine chips, and the composition of the cooking liquor was changed to 16% active alkali and 29% sulfidity. gone. The results are shown in Table 5 below.

As shown in Table 5, even when acacia chips are used instead of red pine chips, H-TEMPO or H-TEMPO or As compared with the case of using a nonionic surfactant alone, it was possible to confirm the effects of both the improvement in the selection yield and the reduction in the kappa number.

Claims (5)

Alkaline digestion or sulfite digestion of a lignocellulose material in a chemical solution containing a radical scavenger and a nonionic surfactant;
The alkaline cooking is kraft cooking or sulfite cooking,
The radical scavenger is selected from the group consisting of tetramethylpiperidineoxyl-based radical scavengers and phenol-based radical scavengers,
The tetramethylpiperidineoxyl radical scavenger includes 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-TEMPO), 2,2,6,6-tetramethylpiperidine-1- oxyl, and bis-(2,2,6,6-tetramethylpiperidine-1-oxyl)-sebacate;
The phenolic radical scavenger includes 2-methylphenol, 2-ethylphenol, 2-propylphenol, 2-methoxyphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2 -tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-methylphenol, and 4-tert-butylcatechol (TBC) ;
A method for producing chemical pulp, wherein the nonionic surfactant is selected from the group consisting of polyoxyalkylenealkylamines and polyoxyalkylenealkylethers. 2. The production method according to claim 1 , wherein the cooking includes heating the chemical solution to a temperature of 80.degree. C. to 200.degree. Kraft digestion, sulfite digestion or sulfite digestion of a lignocellulose material in a chemical solution containing a radical scavenger and a nonionic surfactant ;
The radical scavenger is selected from the group consisting of tetramethylpiperidineoxyl-based radical scavengers and phenol-based radical scavengers,
The tetramethylpiperidineoxyl radical scavenger includes 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-TEMPO), 2,2,6,6-tetramethylpiperidine-1- oxyl, and bis-(2,2,6,6-tetramethylpiperidine-1-oxyl)-sebacate;
The phenolic radical scavenger includes 2-methylphenol, 2-ethylphenol, 2-propylphenol, 2-methoxyphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2 -tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-methylphenol, and 4-tert-butylcatechol (TBC) ;
A kraft, sulfite or sulfite cooking method for lignocellulosic materials, wherein said nonionic surfactant is selected from the group consisting of polyoxyalkylenealkylamines and polyoxyalkylenealkylethers. containing a radical scavenger and a nonionic surfactant,
The radical scavenger is selected from the group consisting of tetramethylpiperidineoxyl-based radical scavengers and phenol-based radical scavengers,
The tetramethylpiperidineoxyl radical scavenger includes 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-TEMPO), 2,2,6,6-tetramethylpiperidine-1- oxyl, and bis-(2,2,6,6-tetramethylpiperidine-1-oxyl)-sebacate;
The phenolic radical scavenger includes 2-methylphenol, 2-ethylphenol, 2-propylphenol, 2-methoxyphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2 -tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-methylphenol, and 4-tert-butylcatechol (TBC) ;
The nonionic surfactant is selected from the group consisting of polyoxyalkylene alkylamines and polyoxyalkylene alkyl ethers.
A pulp cooking aid for use in kraft, sulfite or sulfite cooking of lignocellulosic material . A first component containing a radical scavenger and a second component containing a nonionic surfactant,
The radical scavenger is selected from the group consisting of tetramethylpiperidineoxyl-based radical scavengers and phenol-based radical scavengers,
The tetramethylpiperidineoxyl radical scavenger includes 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (H-TEMPO), 2,2,6,6-tetramethylpiperidine-1- oxyl, and bis-(2,2,6,6-tetramethylpiperidine-1-oxyl)-sebacate;
The phenolic radical scavenger includes 2-methylphenol, 2-ethylphenol, 2-propylphenol, 2-methoxyphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,6-dimethoxyphenol, 2 -tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-methylphenol, and 4-tert-butylcatechol (TBC) ;
The nonionic surfactant is selected from the group consisting of polyoxyalkylene alkylamines and polyoxyalkylene alkyl ethers.
A pulp cooking composition for use in kraft, sulfite or sulfite cooking of lignocellulosic material .

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