ES2598509T3 - Paper product dropout rate - Google Patents

Abstract

A method for treating a cellulose pulp suspension, comprising (i) the step of subjecting the cellulose pulp fibers to an aqueous solution of a manganese transition metal catalyst and hydrogen peroxide at a pH of from 6 to 13 and (ii) subjecting the pulp to a refining process until a Shopper Riegler (SR) value of 10 at 90° is obtained and the resulting pulp is processed to give paper, tissue paper or cardboard, where the catalyst of transition metal manganese is present at a concentration of 0.0005 to 0.2 kg/tonne of oven dried pulp and hydrogen peroxide is present at a concentration of 0.1 to 25 kg/tonne of oven dried pulp, the manganese transition metal catalyst is preformed and is a mononuclear Mn(II), Mn(III), Mn(IV) transition metal catalyst, or Mn(II)Mn(II), Mn(II)Mn(III) ), Mn(III)Mn(III), Mn(III)Mn(IV), or dinuclear Mn(IV)Mn(IV), and the transition metal catalyst ligand has the formula (I):**Formula** in which:**Formula** p is 3; R is independently selected from: hydrogen, C1-C6 alkyl, C2OH, C1COOH, and pyridin-2-ylmethyl; R1, R2, R3 and R4 are independently selected from: H, C1-C4 alkyl and C1-C4 alkylhydroxy.

Description

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DESCRIPTION

Tadice for paper products waste Field of the invention

The present invention relates to a new paper pulp refining process.

Background of the invention

The pulp for the manufacture of paper, tissue paper, cardboard or related products can be obtained from wood pulp and other sources (for example, hemp, straw, cotton). The vast majority of the raw material is wood pulp, which can be soft wood or hardwood raw material. The softwood fibers come from coniferous trees that have aciculas, such as pine, spruce, alpine fir and Douglas fir. Hardwood fibers are obtained from deciduous trees of various types, such as birch, eucalyptus and acacia. The mechanical pulp contains most of the original lignin, while in the chemical pulp most of the lignin has been removed.

Among the distinctive differences between softwood (SW) and hardwood (HW) fibers are the length of the individual cellulosic fibers of the wood, the roughness of the fibers and the stiffness / collapsibility of the fibers.

Hardwood and softwood should be subjected to specific mechanical treatments (refining) to convert the wood into a fibrous suspension used in the formation of a paper web. The fibers of cellulose pulp suspensions are mechanically treated to change the properties of the fibers. The cellulose pulp suspension is transformed into a product that has better tensile / tear resistance properties, higher wear indexes (Shopper Riegler), greater amount of fines and better properties for the manufacture of tissue paper / tissue compared to to those of the initial cellulose pulp suspension. Higher wear rates lead to a decrease in dehydration capacity for paper / tissue paper manufacturing, which increases the energy needed to dry the paper and slows the papermaking speed. On the other hand, too low wear rates produce tissue paper / paper that is not strong enough. Refining is important for the properties of both chemical and mechanical pulp. Apart from dehydration, it should also be taken into account that the energy consumption during the refining process is high.

A chemical process for modulating cellulosic fibers by treating the fibers with iron salts and hydrogen peroxide has been disclosed in WO 2005/028744; Kraft softwood pulp treatment leads to fiber properties that resemble those of hardwood fibers.

WO 2004/022842 discloses a reduced energy process to refine the mechanical pulp after treatment with a pectinase enzyme to produce pulp with certain wear properties.

EP 0458397 discloses the use of 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-TACN) manganese complexes as bleaching and oxidation catalysts and their use for textile and pulp bleaching processes.

US Application 2001 / 0025695A1, Patt et al, discloses the use of CO and PF6- salts of 1,2-bis- (4,7-dimethyl-1,4,7-triazacyclonon-1 manganese complexes) -il) ethane (Me4-DTNE) and Me3-TACN, respectively, for the delignification and bleaching of wood pulp. Although the loss of viscosity described when a manganese compound comprising Me4-DTNE is used is absent or small, the loss of viscosity when a manganese compound comprising Me3-TACN is used is much greater. It is known that cellulose having a lower viscosity gives a lower resistance role (Pulp Bleaching, Principle and Practice, C.W. Dence, D.W. Reeve ed., Tappi, Atlanta, 1996).

WO 2007/125517 discloses the use of 1,2, bis- (4,7-dimethyl-1,4,7-triazacyclonon-1-yl) -ethane (Me4-DTNE) and Me3-TACN with buffer and sequestrants for the bleaching of cellulosic substrates.

WO 2008/086937 discloses the use of 1,2-bis- (4,7-dimethyl-1,4,7-triazacyclonon-1-yl) -ethane (Me4-DTNE) and Me3-TACN for the bleaching of cellulosic substrates, keeping the pH constant.

US 2002/0066542 A1 describes compounds of transition metal complexes of polydentate ligands, in particular cobalt and the use of such compounds in a method of delignification and bleaching. Reference experiments performed with a manganese complex comprising Me3-TACN showed a loss of viscosity, while the other compounds described showed no significant changes in viscosity.

It would be desirable to provide a method that allows a paper / tissue paper manufacturer to use a refining process with a lower level of wear that achieves the same resistance properties of the pulp as the

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conventionally provided by mechanical means.

Summary of the invention

We have found that the treatment of cellulosic fibers using a preformed transition metal complex of azadiclic molecules and hydrogen peroxide improves the refining effect of these fibers. The treatment can be carried out before, during or after the refining process, generally before or during the refining process. Improved refining properties can be observed by increasing tensile strength properties with the same mechanical energy input and the same Shopper Riegler- (SR) value.

In addition, despite the fact that within the field of pulp / paper in which it is widely recognized that the significant reduction in the loss of cellulose viscosity is not desirable for papermaking properties and that the use of Manganese catalysts comprising Me3-TACN produces a significant loss of viscosity, according to different studies, it is particularly surprising to have found that the use of such catalysts leads to an improvement of the refining process effect on fiber properties.

The present invention can be applied to chemical and mechanical pulp, including recycling pulp, for the production of paper, tissue paper or cardboard.

We have found that the energy consumption and the time required to obtain a cellulose pulp suspension that can be further processed to form a band that has a better wear, can be reduced by the action of a manganese catalyst together with hydrogen peroxide.

In a first aspect the present invention provides a method for the treatment of a cellulose pulp suspension comprising (i) the step of subjecting the cellulose pulp fibers to an aqueous solution of a manganese transition metal catalyst and peroxide of hydrogen at a pH of 6 to 13 and (ii) subject the paste to a refining process until a Shopper Riegler (SR) value of 10 to 90 ° is obtained and the resulting paste is processed on paper, tissue paper or cardboard , in which the manganese transition metal catalyst is present in a concentration of 0.0005 to 0.2 kg / tonne of oven-dried pulp and hydrogen peroxide is present in a concentration of 0.1 to 25 kg / ton of oven-dried pulp, the manganese transition metal catalyst is previously formed and is a transition metal catalyst Mn (II), Mn (III), Mn (IV) mononuclear or Mn (M) Mn (M), Mn (N) Mn (IM), Mn (MI) Mn (MI), Mn (III) Mn (IV) or Mn (IV) Mn (IV) dinuclear and the catalyst ligand Transition metal has the formula (I):

in which:

image 1

image2

p is 3;

R is independently selected from: hydrogen, C1-C6 alkyl, C2OH, C1COOH and pyridin-2-ylmethyl;

Ri, R2, R3 and R4 are independently selected from: H, C1-C4 alkyl and C1-C4 alkylhydroxy.

In a second aspect, the invention provides the use of an aqueous solution of a manganese transition metal catalyst and hydrogen peroxide at a pH of 6 to 13, in which the manganese transition metal catalyst is previously formed and is a transition metal catalyst Mn (II), Mn (III), Mn (IV) mononuclear or Mn (M) Mn (M), Mn (N) Mn (IM), Mn (MI) Mn (MI), Mn ( NI) Mn (IV) or Mn (IV) Mn (IV) dinuclear and the transition metal catalyst ligand has the formula (I):

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image3

in which

R

I

----- N [CR1R, CR3R4)

p is 3;

R is independently selected from: hydrogen, C1-C6 alkyl, C2OH, C1COOH and pyridin-2-ylmethyl;

Ri, R2, R3 and R4 are independently selected from: H, C1-C4 alkyl and C1-C4 alkylhydroxy.

to increase the degree of increase in the rate of depletion of cellulose pulp fibers in a process of

refined.

According to the first and second aspects of the invention, each R in the ligand of formula (I) is independently selected from:

hydrogen, C1-C6 alkyl, C2OH, CiCOOH and pyridin-2-ylmethyl. It is particularly unexpected for these ligands that do not form bridges, in which no R is attached to the N of another Q of another ring through an ethylene bridge, which are suitable for use in accordance with the method of the present invention, since prior art reduction in viscosity has been demonstrated when delignification reactions were carried out using transition metal catalysts comprising such a ligand.

The rate of wear (SR) is a standard measure that is determined by the Shopper Riegler method for the determination of drainage according to EN ISO 5267-1; The drain rate (SR) as used herein has been measured by this method.

The concentration of the catalyst and hydrogen peroxide will have an effect on the time of refining treatment of the paste that is required as well as the relationship between the mass of the paste and the amount of active ingredients used. In this sense, to optimize the conditions of the active ingredient concentration variables, the temperature, pH and time are variables that can be changed.

It is preferred that the treatment time of the paste with the catalyst and hydrogen peroxide is from 1 min to 4 h, more preferred from 5 min to 3 h, and most preferred from 10 min to 2 h. In addition, it is preferred that the process temperature using the catalyst and hydrogen peroxide is 30 to 95 ° C and more preferably between 40 and 90 ° C. The pH of the process using the catalyst and hydrogen peroxide is preferably between pH 8 and 12.

The transition metal and hydrogen peroxide complex can be added in a conventional bleaching stage. In another alternative, the transition metal and hydrogen peroxide complex can be added before or during the refining stage, for example, to the pulp that has already been bleached in one or more stages of delignification and bleaching, that is, to Chemical paste The chemical paste so treated may have been delignified / bleached by contact with hydrogen peroxide and a transition metal catalyst, for example, as defined in accordance with the present invention. In another alternative, the chemical pulp can be produced in another way, for example, by non-catalytic bleaching of the pulp, for example, using ozone, chlorine dioxide or non-catalytic bleaching with hydrogen peroxide.

In another alternative, the manganese catalyst together with hydrogen peroxide can be used in a bleaching stage, and again after the bleaching stage, before or during the refining stage.

Often, in the case of mechanical pulp and in the processing of recycling pulp, a bleaching stage is carried out, for example that involves the use of hydrogen peroxide. In such cases, the manganese transition metal catalyst defined in accordance with the first and second aspects of the invention could also be included. Sometimes, a reductive bleaching stage with dithionite can be used to treat the recycle pulp (at which bleaching stage the manganese transition metal catalyst will not be added). In another alternative, the manganese transition metal catalyst and hydrogen peroxide can be used to treat the mechanical pulp and the recycle pulp, in particular before or during the mechanical refining process, after it has been bleached with peroxide of hydrogen and / or with dithionite.

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In another alternative, the manganese catalyst together with hydrogen peroxide can be used in a bleaching stage, and again after the bleaching stage, before or during the refining stage.

These possibilities are analyzed in more detail below. Normally a washing step can be carried out, but it is not necessarily carried out between the addition of the transition metal catalyst and the hydrogen peroxide and the refining process (if the first one is carried out before the last one).

It will be appreciated that the amount of transition metal catalyst / hydrogen peroxide required per tonne of pulp (oven dried) is essentially in molar ratios, although it is normal in industry to express the amounts by weight. In this sense, the range of transition metal catalyst required per ton of pulp (dried in the oven) is in the range of 0.0005 to 0.2 kg per ton of pulp (dried in the oven). (0.0001 to 1 kg per ton of pasta (dried in the oven) equals approximately 0.1 to 1,500 mmol / ton of pasta (dried in the oven)). The hydrogen peroxide (100%) per ton of pasta (oven dried) is in the range of 0.1 to 25 kg, more preferably 0.5 to 25 kg, most preferably 1 to 25 kg. It is understood that each of the concentration ranges of the transition metal catalyst disclosed herein can be combined with each of the hydrogen peroxide ranges disclosed herein.

The molar ratio of transition metal catalyst: hydrogen peroxide is preferably in the range of 1: 100 to 1: 10,000.

Taking into account all of the above, it is routine for a technician skilled in the art to determine the test and error conditions to produce the drain index (SR) and apply the conditions to obtain and optimize the paste having the drain index (SR ) desired at an industrial level band.

Detailed description of the invention

The pulp to produce paper or cardboard grades is fed into a paper machine where a paper band is formed and the water is removed therefrom by pressing and drying.

Pressing the blade removes water by force. Once the water is forced out of the sheet, felt is used to collect the water. When paper is manufactured by hand, a sheet of blotting paper is used. The pulp for the manufacture of grades of tissue paper or kitchen paper is dehydrated and dried without pressure, to maintain adequate absorbency and smoothness properties.

Drying involves the use of air and or heat to remove water from the sheet of paper. In the early days of papermaking this was done by hanging the sheets of paper as clothes are laid. In more modern times, various forms of hot drying mechanisms are used. In the paper machine, the most common is the steam heated cylinder dryer. These dryers can be heated to temperatures above 200 ° F (93 ° C) and are used in long sequences of more than 40 cylinders. The heat produced by these can easily dry the paper to less than 6% humidity.

There are specific procedures to produce tissue paper. See Paper and Board Grades, Volume 18, Chapter 4, published by the Finnish Paper Engineers' Association and TAPPI (2000).

We have found that the treatment of a cellulose pulp suspension with a manganese transition metal catalyst and hydrogen peroxide changes the degree to which the pulp reacts to a mechanical refining process, as measured by its rate of wear ( Shopper-Riegler - SR), to produce a band made from cellulose pulp suspension. Treatment with the manganese catalyst can be done before mechanical refining, during or after the mechanical refining process. For example, and as discussed below, the catalyst / hydrogen peroxide can be added to a pulp mixture or a pulp deposit after mechanical refining, where the pulp can be stored before dehydration.

The relationship between tensile strength and wear is improved, that is, either by increasing the resistance with the same rate of wear or the same resistance with a lower rate of wear. By controlling the treatment conditions, an optimal rate of drainage of the final product is obtained. In addition, an increase in the specific volume can be achieved with the same refining, which is especially important for tissue paper.

We have found that the treatment of a cellulose pulp suspension and the monitoring of concentration and time variables allows an optimal rate of wear for different periods of time.

The term oven-dried pasta refers to the pasta being dried at 100-105 ° C until a constant weight is achieved. Reference is made to the TAPPI T240 om-93 (1993) test.

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REFINED

Different types of equipment are frequently used to mechanically treat cellulose pulp. In many factories, beaters have been used, including Hollander beaters, but now they have been largely replaced by conical and disc refiners, which can operate in continuous processes. The conical refiners are small angle refiners (Jordan), medium angle refiners (Conflo) and large angle refiners (Claflin). Group disc refiners comprise three types, single-disc, double-disc or multi-disc refiners.

Refining can be done at low consistency (2-6%), medium consistency (10-20%) or high consistency (30-35%). Depending on the requirements of the final product, different options can be chosen for optimal consistency processing. See Paper and Board Grades, Papermaking Part 1. Stock Preparation and Wet End, Volume 18, Chapter 4, published by the Finnish Paper Engineers' Association and TAPPI (2000).

The processes can be either batch or continuous, the latter being frequently preferred due to cost reasons and because the quality control is easier.

In many cases, different types of wood pulp are mixed, such as softwood and hardwood pulp. One of these or both can be refined independently. Often, more refiners are used in series to improve energy benefits / requirements for the treatment of pulp.

The refining can be carried out in the chemical paste, the mechanical paste and in the recycling paste, all object of the present invention.

Depending on the application, different levels of refining can be applied. For grades of tissue paper and kitchen paper, a low refining is carried out, to ensure a good specific volume, smoothness, absorbency and brightness. A low refining is beneficial for the previous properties, but negatively affects the resistance properties. Therefore, resistance agents are often added in wet and / or dry. After refining, Shopper Riegler indices of between 10 and 30 ° are often obtained.

For printing and writing paper, the printability and operability of the machine are key parameters. The document must be clean and bright, have the properties of smoothness, compressibility, adequate ink penetration and sufficient resistance for printing operations. A minimum opacity is another important characteristic. Therefore, these papers need good refining control to develop internal bond strength and to obtain the proper level of smoothness and formation for final use. The bleached cardboard grades, used among others for the packaging of frozen food and liquids, and for paper plates and cups, need a good stiffness and specific volume with adequate smoothness and printability. Internal union, foldability and dimensional stability are also important factors. Therefore, a sufficient degree of refining is also required to obtain these properties (without diminishing the specific volume and stiffness too much). Frequently for these applications, Shopper Riegler indexes are required after refining between 15 and 50 °.

Dense papers need a significant amount of refining, depending on the particular needs of the product. Removable base papers, glassine paper and waxed paper require extensive refining to obtain the desired balance between strength and appearance properties. Especially if the objective is to manufacture transparent papers, considerable energy requirements for the refining processes must be met. SR indices of up to 90 ° may be required.

Mechanical pulp often requires refining to produce paper or cardboard materials that have the appropriate physical properties. When mechanical pulp is refined, Shopper-Riegler indices of between 20 and 80 ° are often reached.

The degree of refining can be monitored online. The energy input is the most important parameter to determine the degree of refining. There are control systems to monitor online the refining process and the adjustment of the energy supply according to the requirements. Probes to monitor refiner load, temperature changes, flow / consistency, drain / drain (SR), etc. The main process variables include temperature, pH, consistency, additives, pretreatments, production rate and applied energy.

Treatment of cellulosic fibers with manganese catalyst and hydrogen peroxide

The application of manganese catalyst and hydrogen peroxide to treat cellulosic fibers can be done at different stages during the process of treating the fibers / papermaking. This may be either before the mechanical refining process, during the mechanical refining process or after the mechanical refining process, generally before or during the mechanical refining process.

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Generally, pulp that has been bleached in one or more stages of delignification and bleaching, chemical pulp, can be used to further treat to produce tissue paper, paper or cardboard. However, within the scope of this invention, pulp containing lignin (mechanical pulp) or recycled wood pulp can also be used. In the integrated factories, a wet paste suspension is contacted in the factory. When paper producers obtain pulp from other mills, the pulp sheets are first placed in a tank and disintegrated to obtain a suspension of diluted pulp, which can be further processed.

In pulp mills, chemical pulp is generally bleached with hydrogen peroxide and / or other bleaching processes that use, for example, ozone or chlorine dioxide. The mechanical and recycling pulp is often bleached with hydrogen peroxide to increase the brightness of the pulp. During one or more of these bleaching stages, hydrogen peroxide can be used together with the manganese catalyst to obtain the cellulose that can be treated in the refining process. The manganese catalyst and hydrogen peroxide can be added during the different stages in the factory.

In a pasta mixer, chemicals are added to the pasta which are thoroughly mixed. Within the scope of this invention, the catalyst and hydrogen peroxide could be added to the pasta mixer to achieve paste treatment. This can be done in low consistency mixers (mixers with continuous agitation, tower mixers, dynamic mixers or static mixers), medium consistency mixers (PEG mixers, high shear mixers) or high consistency mixers, including kneading and mixing mixers disc type In a steam mixer, water vapor is added to the pasta to increase the temperature of the pasta. The catalyst and hydrogen peroxide can also be added to the paste in a steam mixer.

See Pulp Bleaching, Principle and Practice, C.W. Dence, D.W. Reeve ed., Tappi, Atlanta, 1996, infra).

After the addition of the chemical bleaching products of the pulp to the mixers, most of the bleaching of the pulp takes place in the pulp bleaching tower, after which the pulp is washed. Since bleaching processes are generally slow (2-4 hours usually), bleaching towers tend to be large. However, smaller paste retention lines are sometimes used to allow certain bleaching or treatment reactions to occur. As the processes are generally continuous, the pulp moves slowly upwards (upward flow tower), downwards (downward flow tower) or a combination thereof (upward-downward flowing tower). Within the scope of this invention, treatment with the catalyst and hydrogen peroxide may be much shorter, which allows relatively small treatment towers.

In a pulp washing equipment, the treated pulp is usually washed with chemicals at an earlier stage of the treatment process. For example, the acid chlorine dioxide is washed with a solution of NaOH, to remove alkaline soluble lignin residues and prepare the paste for the next step. Within the scope of this invention, the manganese catalyst and hydrogen peroxide could be added to a (additional) mixer, making use of its rapid reaction kinetics for the treatment of the paste with the catalyst.

A pulp storage tower is designed to store the pulp for further processing after a period of time. Generally, such a storage tower can be found before the processes where the pulp bleaching stages take place or after the final bleaching stage, before, for example, transport to the paper mill. The catalyst and hydrogen peroxide can be added together with the pulp when they enter this storage tower, which allows a slow pulp treatment process.

A shredder is used to dilute paper waste (destined pulp) and add alkali and hydrogen peroxide to bleach the destined pulp. To this defibrator the manganese catalyst could be added to allow the treatment of the paste destined by the catalyst.

The manganese catalyst and hydrogen peroxide can also be added to the cellulose pulp before the refining process in the paper mill, such as in the shredder, the high density pulp tank, the pulp waiting tank, the dough mixing tank or in the dough leveling tanks. The pulp shredder and high density tank are commonly used to prepare dry raw material, semi-processed paper and recycling paper in a pumpable state by adding water and then mixing it with water. In the pulp mixing tank, two or more different types of pulp are mixed, optionally refined and stored for further processing, such as softwood and hardwood pulp. In leveling tanks, the consistency of wood pulp is reduced to the desired levels.

Mechanical pulp is often treated in waiting tanks to treat fibers that are distorted (twisted, curved or crooked). Generally the mechanical paste is diluted to 1-2% consistency, heated to 70-90 ° C, stirred for at least 20 minutes, after which it is further processed. Pulp deposits, similar to those for pulp storage described above, are used to store wood pulp. Also the aforementioned tanks are often used to store the wood pulp and ensure a constant flow of the pulp to be treated in subsequent processes. Pasta

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Wood can be shipped from pulp bleaching factories or it may have been produced on site (integrated factory).

In another alternative, the catalyst / hydrogen peroxide can be added just before the pulp refiner and allowed to react with the cellulose during the refining process. Due to the release of heat during refining, the requirement of additional energy to obtain an optimal treatment effect by the catalyst will be reduced or absent. Different refining equipment, including beaters, can be used; Hollander beaters; small angle conical refiners; medium angle conical refiners; large angle conical refiners; single disc refiners; double disc refiners; multi-disc refiners. See Paper and Board Grades, Papermaking Part 1. Stock Preparation and Wet End, Volume 18, Chapter 4 published by the Finnish Paper Engineers' Association and TAPPI (2000) and C.F. Baker, Tappi Journal, 78, 147, 1995.

Finally, the catalyst / hydrogen peroxide can be added after the mechanical refining stage, for example, in the pulp mixing tank (where the different sources of wood pulp are mixed) or in the pulp deposit. For example, mechanical pulp can be treated in this way.

In another alternative, the manganese catalyst together with hydrogen peroxide can be used both in a bleaching stage, and again after the bleaching stage, before or during the refining stage.

Transition Metal Catalyst

The manganese transition metal catalyst used can be non-deliquescent using counterions such as PFs- or ClO4-. However, for industrial substrates it is preferred that the transition metal complex be water soluble. It is preferred that the preformed transition metal is in the form of a salt such that it has a water solubility of at least 30 g / l, for example at least 50 g / l at 20 ° C. Preferred salts are chloride, acetate, sulfate and nitrate. These salts are described in WO 2006/125517.

According to the invention, each R in the ligand of formula (I) is independently selected from: hydrogen, C1-C6 alkyl, C2OH, C1COOH and pyridin-2-ylmethyl. According to particular embodiments, R is independently selected from: hydrogen, CH3, C2H5, CH2CH2OH and CH2COOH.

Preferably, Ri, R2, R3 and R4 are independently selected from: H and Me.

According to particular embodiments, Ri, R2, R3 and R4 are independently selected from: H and Me. Most preferably, the catalyst is derived from 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-TACN).

The preformed transition metal catalyst salt is preferably a dinuclear Mn (III) or Mn (IV) complex with at least one O2- bridge. In accordance with certain embodiments of the invention, the transition metal catalyst can be a salt, such as the salts described hereinbefore, of the complex [Mn (IV) 2 (MO) 3 (Me3TACN) 2] 2+ .

The level of application of manganese catalysts may vary depending on the application, but will be between 0.0005 and 0.2 kg / t of oven-dried paste (p.s.h.).

HYDROGEN PER6XIDE

Hydrogen peroxide is provided as an aqueous solution as is, or as peroxy salts, such as, percarbonate, etc. However, for reasons of cost, liquid hydrogen peroxide is preferred. The level of hydrogen peroxide applied is: from 0.1 kg / t to 25 kg / t of dried pasta (p.s.h.), more preferably from 0.3 to 25 kg / t p.s.h. and most preferred 0.5 to 25 kg / t p.s.h.

The reagents are preferably provided in an alkaline medium, optimally between pH 8 and 13, whose alkalinity is preferably provided by sodium hydroxide or sodium carbonate.

The temperature of the treatment process is preferably between 30 ° C and 95 ° C and more preferably between 40 ° C and 90 ° C.

The treatment time with the catalyst and hydrogen peroxide is between 1 minute and 4 hours, more preferably between 5 minutes and 3 hours and most preferably between 10 minutes and 2 hours.

Sequestrant

Many sequestrants are suitable for use with the present invention. Examples include aminophosphonate and carboxylate sequestrants, for example, aminophosphonate and aminocarboxylate sequestrants. Suitable sequestrants include ethylenediamine tetraacetate (EDTA), polyphosphonates such as Dequest ™ and non-phosphate stabilizers such as EDDS (ethylenediamine di-succinic acid).

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The sequestrant used in the step of treatment with manganese catalyst and hydrogen peroxide is preferably an aminocarboxylate sequestrant or mixtures thereof. The following are preferred examples of aminocarboxylate sequestrants: ethylenediaminetetraacetic acid (EDTA), N-hydroxyethylenediaminetetracetic acid (HEDTA), iminodisuccinic acid (IDS), nitrilotriacetic acid (NTA), N-hydroxyethylacetic acetic acid, diethyl acidic acid (DTP) MGDA), ethylenediamine di-succinic acid (EDDS) and alanine-N, N-diacetic acid. A more preferred aminocarboxylate sequestrant is diethylenetriaminepentaacetic acid (DTPA).

Phosphonate sequestrants can also be used; a preferred phosphonate sequestrant is Dequest 2066 diethylenetriamin penta (sodium salt of methylene phosphonic acid)

It will be understood that, when used, a sequestrant may be present in the form of free acid or salt. For example, if it is present as a salt, this may be an alkali metal, alkaline earth metal, ammonium salt or substituted ammonium salt. Generally, a sequestrant, if present, is in its free acid form or as a sodium salt, potassium or magnesium salt. An example of a sodium salt of an aminocarboxylate sequestrant is the pentanedic salt of diethylene anthramin penta (methylenephosphonic acid), commercially available under the trade name Dequest 2066A.

The most preferred concentration of the sequestrant used in the method is 0.01 to 50 kg / tonne of oven-dried pulp in the solution containing the manganese catalyst and hydrogen peroxide, most preferably 0.03 to 20 kg / ton of oven-dried pasta.

EXPERIMENTAL PART

Experiment 1: Treatment of softwood pulp with hydrogen peroxide with and without [Mn2 (j- O) 3 (Me3TACN) 2] (CH3COO) 2 at pH 11.0 (Me3-TACN = 1,4,7- trimethyl-1,4,7-triazacyclononane).

[Mn2 (j-O) 3 (Me3TACN) 2] (CH3COO) 2 (as a 3.5% aqueous solution) was obtained as disclosed elsewhere (WO2006 / 125517).

Softwood pulp with an ISO starting brightness of 49.9 was treated as follows: To a polyethylene (PE) bottle containing 250 g of oven-dried pulp at 10% consistency, 10 kg / H2O2 was added tpsh (tpsh = ton of oven-dried pasta - equal to 29.4 mM H2O2) and 7.2 kg / tpsh NaOH (equal to 18 mM NaOH). Depending on the experiments, 0.04 kg / [Mn2 (jO) 3 (Me3TAcN) 2] (CH3COO) 2 tpsh (equal to [Mn2 (jO) 3 (Me3TACN) 2] (CH3COO) 2 6.5 jM was added and 1.0 kg / DTPA tpsh (diethylenetriaminepentaacetic acid, pentasodic salt) - (from Akzo Nobel; trade name Dissolvine D50; purity is 50%). The initial pH value was pH 11.0 (measured at 20 ° C).

Note 1: This softwood pulp has been delignified in a stage of O2- tarignification and partially bleached in an additional stage with CO2.

Note 2: In practice, paste containing 35.6% dry matter and 64.4% water (35.6% dry matter) is used. Therefore, 702.3 g of "wet" pasta was used for each experiment.

Note 3: All experiments were carried out at 10% consistency.

The PE bottles are placed in a pre-heated water bath (62.5 ° C) for 1 hour and shaken during the entire bleaching process. Subsequently, the pasta mixture is filtered through a Buchner funnel and washed with copious amounts of demineralized water. Using the filtrate, the consumption of H2O2 is measured. The following analyzes are carried out on bleached pulp: kappa index, gloss and intrinsic viscosity.

The results of the experiments are given in Table 1.

Table 1 Results of softwood pulp treatment using [Mn2 (jO) 3 (Me3TACN) 2] (CH3COO) 2, [Mn2 (j-O) 3 (Me3TACN) 2] (CH3COO) 2 and DTPA and without [Mn2 (jO) 3 (Me3TACN) 2] (CH3COO) 2 at an initial pH of 11.0 at 60 ° C for

60 minutes.

 N °

 Sample Brightness (ISO%) Visc. Intr. (ml / g) Kappa index H2O2 consumption (kg / tpsh)

 OR

 Untreated (raw) 49.9 764 8.33

 P1

 White (without catalyst, without DTPA) 67.4 753 4.27 7.5

 P2

 0.04 kg / [Mn2 (j-O) 3 (Me3TACN) 2] (CH3COO) 2 tpsh and 1 kg / DTPA tpsh 68.1 701 4.11 7.8

 P3

 0.04 kg / [Mro (j- O) 3 (Me3TACN) 2] (CH3COO) 2 tpsh 66.8 698 4.17 9.6

The results shown in Table 1 show that the addition of [Mn2 ([jO) 3 (Me3TACN) 2] (CH3COO) 2 has some effect on bleaching and the kappa index and a clear effect on viscosity (polymerization degree of cellulose) from soft wood pulp.

5 The treated paste was broken down (DIN EN ISO 5263-1; 2004-12), beaten (PFI mill) (ONORM EN ISO 5264-2; 200305) and the drainage was tested (Schopper-Riegler method, OnORM EN ISO 5267 - 1; 2000-10).

Laboratory test sheets were prepared by the Rapid-Kothen method (ONORM EN ISO 5269-2; 2005-04) and the conditioning of the samples, NC 23/50 (DIN EN 20187; 1993-1911) was carried out. The following 10 tests were carried out using the test sheets: grammage (DIN EN ISO 536; 1996-1908), thickness, specific volume and density (DIN EN ISO 534; 2005-05), air permeability (Bendtsen, ISO 5636/3; 1992-1909), tensile strength, tensile strength, tensile strength, tensile index, ASD and elastic modulus (DIN EN ISO 1924-2; 2009-05), internal bond strength (steering z, TAPPI 541 om-05; 2005), tear strength, tear index (ONORM EN 21974; 1994-1909).

fifteen

The results are given in the following tables.

Table 2 Beat results and drainage of bleached softwood pulp after being treated according to the conditions given in Table 1. P1: without catalyst, without DTPA P2: [Mn2 (j-20 _______ O) 3 (Me3TACN ) 2l (CH3COO) 2 and DTPA P3 [Mn2 (jO) 3 (Me3TACN) 2l (CH3COO) 2 without DTPA ._______

 Sample

 P1 P2 P3

 Drainage

 [SR] [SR] [SR]

 Without beating

 14.0 13.8 14.0

 PFI 2000 Revolutions

 15.9 16.2 16.9

 PFI 5000 Revolutions

 24.1 24.3 23.2

 PFI 7000 Revolutions

 32.7 32.8 32.9

 PFI 9000 Revolutions

 41.6 46.5 45.5

The results shown in Table 2 show that the paste samples treated with catalyst and hydrogen peroxide exhibit similar SR values up to 7000 revolutions as the reference, while when the paste is refined at 9000 revolutions, higher SR values are obtained.

25

Table 3 Resistance and tear values of laboratory sheets prepared using refined paste at 5000 _________________________ revolutions, as shown in Table 2 ._________________________

 Sample

   P1 5000rev P2 5000rev P3 5000rev

 Weight

 [g / m2] 80.2 81.0 80.2

 Thickness

 [Jm] 111 112 113

 Density

 [g / cm3] 0.724 0.725 0.711

 Specific volume

 [cm3 / g] 1,380 1,380 1,407

 Air permeability (Bendtsen)

 [ml / min] 429 435 560

 Tractive force

 [N] 101 111 108

 Breaking Stretch

 [%] 2.96 2.89 2.89

 Tensile strength

 [kN / m] 6.74 7.42 7.21

 traction index

 [Nm / g] 84.1 91.6 89.9

 TORCH

 [J / m2] 136 144 141

 Elastic module

 [GPa] 6.33 6.92 6.76

 Internal bond strength

 [N / cm2] 82.6 81.5 84.1

 Tear resistance

 [mN] 877 827 814

 tear index

 [mN.m2 / g] 10.9 10.2 10.2

The results shown in Table 3 show that the paste samples treated with the catalyst and hydrogen peroxide and refined after 5000 revolutions in the PFI mill, show higher values of tensile strength, tensile energy absorption (TEA ) and tensile indices, decreased tear strength and tear index, while the other parameters are not very affected by the treatment with catalyst and hydrogen peroxide (all with respect to the reference without catalyst - P1). A slight improvement in these tensile strength properties was observed when the catalyst is used in combination with DTPA.

Claims (13)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 1. A method for the treatment of a cellulose pulp suspension, comprising (i) the step of subjecting the cellulose pulp fibers to an aqueous solution of a manganese transition metal catalyst and hydrogen peroxide at a pH of 6 to 13 and (ii) subject the pulp to a refining process until a Shopper Riegler (SR) value of 10 to 90 ° is obtained and the resulting pulp is processed to give paper, tissue paper or cardboard, where the Manganese transition metal catalyst is present in a concentration of 0.0005 to 0.2 kg / tonne of oven-dried pasta and hydrogen peroxide is present in a concentration of 0.1 to 25 kg / tonne of dried pasta furnace, the manganese transition metal catalyst is previously formed and is a transition metal catalyst Mn (II), Mn (III), Mn (IV) mononuclear or Mn (II) Mn (N), Mn (N) Mn (IM), Mn (MI) Mn (IM), Mn (III) Mn (IV) or Mn (IV) Mn (IV) dinuclear and the transition metal catalyst ligand has the formula (I): image 1 in which: R I ---- W ----- [CR ^ .CR-.RJ p is 3; R is independently selected from: hydrogen, C1-C6 alkyl, C2OH, C1COOH and pyridin-2-ylmethyl; Ri, R2, R3 and R4 are independently selected from: H, C1-C4 alkyl and C1-C4 alkylhydroxy. 2. The method according to claim 1, wherein R is independently selected from: hydrogen, CH3, C2H5, CH2CH2OH and CH2COOH. 3. The method according to claim 1 or claim 2, wherein R, Ri, R2, R3 and R4 are independently selected from: H and Me. 4. The method according to claim 1, wherein the catalyst is derived from 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-TACN). 5. The method according to any one of the preceding claims, wherein the pulp is subjected to a refining process until: (i) a Shopper Riegler (SR) value of 10 to 30 ° is achieved to produce tissue paper; (ii) a Shopper Riegler (SR) value of 15 to 50 ° is achieved to produce printing and writing paper; (iii) a Shopper Riegler (SR) value of 50 to 90 ° is achieved to produce tracing paper and transparent paper; or (iv) a Shopper Riegler (SR) value of 20 to 80 ° is reached. 6. The method according to any one of the preceding claims, wherein the catalyst and hydrogen peroxide are added to the pulp in a device selected from: a shredder, a high density pulp tank, a washing equipment of pasta, a pasta waiting tank, a pasta leveling tank, a pasta mixing tank, a pasta refiner, a pasta dilution tank and a pasta tank. 7. The method according to claim 6, wherein the pulp refiner is selected from: beaters, Hollander beaters, small angle conical refiners, medium angle conical refiners, large angle conical refiners, single disc refiners, double disc refiners and multi-disc refiners. 8. The method according to any one of the preceding claims, wherein the catalyst and hydrogen peroxide are added to the pulp during one of the bleaching steps for the chemical, mechanical or recycling treatment of the pulp, by an example, wherein the catalyst and hydrogen peroxide are added to the pulp in a device selected from a pulp mixer, a pulp bleaching tower, a pulp retention duct, a pulp washing equipment, a turret pasta storage, a steam mixer and a 5 10 fifteen twenty 25 30 35 shredder 9. The method according to any one of claims 1 to 7, wherein the pulp fibers have previously undergone a bleaching step. 10. The method according to any one of the preceding claims, wherein the solution containing the catalyst and hydrogen peroxide comprises from 0.01 to 50 kg / tonne of oven-dried pulp of an organic sequestrant, the solution being sequestrant selected from: an aminophosphonate sequestrant and a carboxylate sequestrant, for example, wherein the sequestrant is selected from: diethylenetriamin penta (sodium salt of methylenephosphonic acid), MGDA (methylglycine diacetate), GLDA (glutamic acid diacetate), IDS (iminodissucinate), EDDS (ethylenediamine disuccinate), EDTA (ethylenediamine tetraacetate) and DTPA (diethylene acetate) 11. A method according to any one of the preceding claims, wherein the energy contribution to the refining treatment is controlled and, based on the energy input threshold, the pulp is processed to give paper, tissue paper or paperboard. 12. Use of an aqueous solution of a manganese transition metal catalyst and hydrogen peroxide at a pH of 6 to 13, wherein the manganese transition metal catalyst is previously formed and is a Mn (II transition metal catalyst) ), Mn (III), Mn (IV) mononuclear or Mn (M) Mn (M), Mn (M) Mn (MI), Mn (IM) Mn (IM), Mn (III) Mn (IV) or Mn (IV) Dinuclear Mn (IV) and the transition metal catalyst ligand has the formula (I): in which: image2 image3 p is 3; R is independently selected from: hydrogen, C1-C6 alkyl, C2OH, C1COOH and pyridin-2-ylmethyl; Ri, R2, R3 and R4 are independently selected from: H, C1-C4 alkyl and C1-C4 alkylhydroxy, to increase the degree of increase in the rate of depletion of cellulose pulp fibers in a process of refined. 13. The use of claim 12 wherein the use comprises a method as defined in any one of claims 1 to 11.