FI121310B - Process for treating lignocellulosic materials containing pectin - Google Patents

Description

FIELD OF THE INVENTION Field of the Invention This invention relates to a process for treating pectin-containing lignocellulosic materials.

The present invention relates to a process for treating pectin-containing lignocellulose raw materials in a high-yield pulping process using one or more processing steps under alkaline conditions. More particularly, the present invention relates to a process for increasing the bleachability of the final pulp and also for reducing the cation consumption of process waters. The present invention also relates to pulp, paper, board or tissue produced by this process.

Background of the Invention

Mechanical pulping aims to convert the raw material into sufficiently high quality fibers without serious loss of yields. The properties of the mechanical pulps can be improved before, during, during the pulverization of coarse-grained fibers, or after finishing after defibration. In order to produce a high quality high yield pulp, it is generally important to increase the brightness by removing colored or chromophore structures without sacrificing the process yield. An extensive review of the state of the art can be found in Sundholm, J.: Mechanical Pulping, Book 5, FapetOy 1999.

Alkaline treatments are generally used for the pre-treatment of chips, such as in the production of chemical pulp, or in bleaching of mechanical or chemimechanical pulps, such as ground, hot and chemical pulp, with peroxide.

The chromophores of mechanical pulps are mainly derived from lignin. These structures are partially removed or converted to non-chromophore structures in bleaching processes. However, during the mechanical pulping process steps under primary conditions, that is, mainly during chip pre-treatment or pulp bleaching, new chromophore structures are also formed, due to the process conditions, i.e. high temperatures and high alkalinity. Alkaline darkening is a known phenomenon that produces orthoquinones and coniferaldehydes.

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Wood pectin is one of the major sources of the so-called '' anionic debris '' and the alkali-induced 'unbleached' chromophores present in the end product.

When pectin is cleaved, large pectin molecules break into smaller fragments, which are capable of diffusing out of the wood ('' anionic debris '') and form new chromophoric (terminal) end groups.

The present invention provided assurance that temperature is a critical variable that determines the degree of pectin degradation under alkaline conditions. The increase in temperature results in a sharp increase in cleavage and a decrease in the molecular weight of the fragments, thereby increasing the formation of chromophore end groups.

In this regard, by analogy with lowering the temperature, the result is a reduction in vigorous cleavage and an increase in the molecular weight of the fragments, thereby reducing the formation of chromophore end groups.

Alkaline-induced cleavage of pectin is a very rapid reaction: once the pectin has reacted (after cleavage), its prolonged time treatment at a temperature above (or below) the initial temperature no longer promotes cleavage.

SUMMARY OF THE INVENTION: The present invention relates to an industrial-scale bleach enhancement method based on preventing the formation of stable chromophores and reducing the release of anionic debris in alkali treatment of pectin-containing materials such as chips pre-treatment or peroxide bleaching. The invention is based on the observation that when alkali is added to the process, the temperature must be low, for example 70 ° C or below, since pectin demethylation occurs surprisingly rapidly, after which alkali-induced degradation of pectin is minimized even if the temperature is increased or increased. Compared to the high temperature (-100 ° C) commonly used in these processes, this process produces twice the amount of '' anionic debris '' in process water and prevents loss of about 2% of ISO brightness.

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The release of pectins from spruce TMP doubled in high temperature treatments (80-100 ° C) compared to the low temperature treatment (20-70 ° C) of the present invention. This was also found in the lower cation consumption of process waters (~ 25%). At the same time, the brightness of the Per-5 oxide bleached spruce pulps was up to 1-2% ISO higher for the impregnated pulps under low temperature conditions compared to the high temperature conditions prior to raising the temperature to the desired reaction temperature.

The present invention provides a process for treating pectin-containing ligno-10 cellulose raw materials in a high yield mass production process based on the use of one or more processing steps under alkaline conditions, wherein the alkaline chemicals are used in the first temperature treatment step (T-ι) once in contact with pectin-containing material 15 before one or more subsequent treatment steps at the same or higher temperature (T2). This results, for example, in improved brightness and reduced amount of ionic substances released into the process waters.

The present invention further provides pulp or bleached pulp obtained by the process of this invention and paper, cardboard or tissue paper obtained from said pulp.

One object of the present invention relates to increasing the bleaching of pectin-containing material and, for this reason, to increasing the brightness of bleached pulps, for example.

Yet another object of the present invention relates to reducing the release of anionic pectin agents.

Yet another object of the present invention relates to reducing the cation consumption of process water.

Yet another object of the present invention relates to improving certain papermaking properties such as pulp quality.

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Brief Description of the Drawings

Figure 1 shows that degradation of pectin under alkaline conditions at elevated temperature results in an increase in chromophore formation (1 mg / ml pectin, 94% methylesterified, 0.3 ml 1 M NaOH, 20-100 ° C, 30 min).

Figure 2 illustrates the principle of the present invention. Figure 2A is a block diagram of the steps of the present invention. Figure 2B shows the desired properties of the paper, the brightness, the water (amount of ionic substances) and the properties of the fibers, which are interdependent.

Figure 3 shows the kinetics of chain breakage at pH 11 and 40 ° C with hand-modeled model pectin (94% methylesterified).

Figure 4 shows a processing diagram of a preliminary series of experiments.

Figure 5 shows how Xyl and GalA are released into water after alkaline treatment of spruce "pure" TMP at different starting temperatures.

Figure 6 shows a processing diagram of a second set of experiments.

Fig. 7 shows the ISO degree of whiteness of sheets made of bleached TMP at different starting temperatures.

Figure 8 shows a processing diagram of the final set of experiments.

Fig. 9 shows the cation consumption of water at various initial temperatures after or without the alkaline treatment of TMP with or without peroxide. Peroxide acts as a buffer and >>>: 20 weakens the effect of alkali.

Figure 10 shows the ISO brightness percentage of sheets made of bleached and alkali-treated TMP at different starting temperatures. The lower temperature used at the beginning of the bleaching stage resulted in a +2% ISO.

DETAILED DESCRIPTION OF THE INVENTION Chemical reactions can generally be influenced by controlling the pH and temperature of the reaction. By controlling chemical reactions in alkali treatment of chips or pulps, some important papermaking properties can be improved.

Pectins are polydispersed polymers and have a backbone of partially methylesterified galacturonic acid (GalA) units with rhamnose 5 (Rha) units between them. Spruce contains 1.5-2% of pectins and aspen 2-2.5% (Pra-novich, AV Sundberg, K. and Holmbom, B. (2003) Chemical changes in thermo-mechanical pulp at alkaline conditions. J. Wood Chem Technol 23 (1): 89-112; Sundberg, A., Sundberg, K., Lillandt, C., and Holmbom, B. (1996) Determination of 5 hemicelluloses and pectin in wood and pulp fibers by acid methanolysis and gas chromatography. .Nord Pulp Pap Res J. 11 (4) 216-219, 226).

The release of pectic substances into process waters increases the amount of so-called '' anionic debris '' in the water cycle. This increases the total consumption of chemicals such as paper chemicals at the wet end of the papermaking machine (PM) and reduces the runnability of the PM 10.

OH 0γ ° · ° Η3 OH ° Y ° 'CH3 oh JZ, a? aD-GalA- ^ aD-GaIA-H> Cf-D-GalA-> aL-Rha— »aD-GalA-> aD-GalA 1 -> 4 1 -> 4 1 -> 2 1 -> 4 1 -> 4

Lignin is generally believed to be the predominant source of chromophores for which the highest brightness limit observed for mechanical silage masses, ~ 80% ISO for conifers and ~ 85% ISO for hardwoods. However, acidic hemicelluloses such as pectins, xylans and other uronans can play a crucial role in limiting the maximum brightness obtained in the peroxide bleaching of mechanical pulps.

Cleavage of the polymeric chain according to the β-elimination mechanism requires the presence of methyl esterified carboxyl groups and is therefore inhibited by demethylation (Kiss J. (1974) Carbohydr. Chem. Biochem. 29: 229 -03; Renard, CMGC and Thibault, J.-F. (1996) Degradation of pectin in alkaline conditions: Kinetics of demethylation (Carbohydrate Res. 286: 139-150). The rates of both demethylation and β-elimination reactions increase with pH. However, increasing pH increases demethylation more than β-elimination, while increasing temperature increases β-elimination more than demethylation. By controlling the temperature at the stages of the alkali treatment process, it is therefore possible to reduce the release of anionic pectic substances and also to increase the whiteness of the mechanical pulps to be bleached.

6 OH 0V0-CH * OH 0V0 ”β-elimination of CH ^ o o-ch3 oh o och3 oh

Pectin undergoes two simultaneous reactions under demineralized conditions: demethylation and β-elimination. The sensitivity of pectin to depolymerization by the action of β-elimination is dependent on the presence of an ester group in galacturonic acid. When the removal of methanol from pectin is complete, β-elimination stops. A double bond appears between the C4 and C5 at the non-reducing end (Kiss, 1974).

Release of pectins from spruce TMP doubles in high temperature (80-100 ° C) treatments compared to the low temperature (20-70 ° C) treatment of the present invention. This was also observed with lower cation consumption (~ 25%) of process waters. At the same time, the lightness of the peroxide bleached spruce pulps under low temperature conditions by the impregnated pulps increases by 1-2% ISO compared to the high temperature conditions prior to raising the temperature to the desired reaction temperature.

The effect of low temperature pretreatment with mechanical aspen pulp (BCTMP) has not been studied. However, it could be expected that the effect would be even more pronounced as aspen contains approximately 25% more pectins than six.

The present invention provides a process for treating pectin-containing ligno-cellulosic feedstock in a high-yield pulping process (prior to a papermaking machine headbox) using one or more processing steps under alkaline conditions. The pectin-containing raw material may be any suitable material, such as wood, coniferous or hardwood or combinations thereof, chopped lignocellulosic raw material such as wood chips, straw, pulp, or high yield pulp.

The alkaline treatment step may be used prior to mechanical pulping or the subsequent alkaline bleaching step (s). Alkaline chemicals may be any suitable alkaline chemicals that provide conditions sufficient for significant demethylation of native pectin methyl esters, typically above pH 9 at room temperature. The alkali starting material may, for example, be derived from hydroxides, carbonates or sulphites, preferably sodium, calcium, ammonium or magnesium hydroxides, carbonates or sulphites, or combinations thereof.

In the process of the present invention, alkaline chemicals are used in a low temperature treatment step (Ti), which refers to the point where the alkali is first contacted with the pectin-containing material prior to one or more subsequent treatment steps at the same or higher temperature (T2). It is important that no prior alkali treatment step is used for the material containing 10 pectins, since alkali-induced cleavage of pectin occurs very rapidly. Conversely, when the alkali is added for the first time at low temperature, the demethylation reaction occurs rapidly, thus preventing the alkali-induced further degradation of pectin by β-elimination reactions, the dose of alkali may be in the range 0.1-10% w / w based on dry state of the pectin-containing material. in terms of.

It is preferred that the pectins contained in the material to be treated are methylesterified. The degree of methyl esterification is generally 20 to 100%, determined as a percentage of galacturonic units containing one methyl ester group, and is preferably 50 to 70%.

The process of the present invention provides improved bleachability of pectin-containing material. This results in an improvement in the brightness of the pulp, as well as a reduction in the chemical consumption and costs required to achieve a particular brightness. In addition, the process waters 25 release a smaller amount of ionic substances. Reduced solids content; in water means less chemical costs in paper making or water treatment and less impact on the environment. It also improves paper machine performance. The quality of the pulp is also better, for example, it has less darkening.

Figure 2 illustrates the principle of the present invention. Figure 2A is a block diagram of the steps of the invention. Tn is one or more (n £ 2) steps T2, T3, T4 ... Figure 2B shows the desired properties of the paper, the brightness, the water (amount of ionic substances) and the properties of the fibers, which are interdependent.

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The high yield pulping process may mean the production of hot pulp or chemical pulp, in which the yield is generally greater than 70%, preferably greater than 80%, and more preferably greater than 85%.

The low temperature in step Ti, as used herein, means a temperature of 70 ° C or lower, preferably below 60 ° C, more preferably below 50 ° C. Normally, a temperature range from room temperature (20 ° C) to said 70 ° C may be used. In one embodiment, the temperature is 50-60 ° C. The duration of said low temperature step or the time interval between T-pn or T2 can range from 1 second to 24 hours, generally less than 10 4 hours. In one embodiment, the time interval is in the range of 1 second to 2 hours. In yet another embodiment, the time interval is in the range of 2 to 10 minutes, for example about 5 minutes. It is important that said time allows for demethylation reactions to occur at low temperature in the seam.

In one embodiment, other chemicals such as chelating, stabilizing and / or bleaching agents, preferably peracid, are also used in step Ti. The chemicals used in step Ti may also be recycled to the next step (s).

In one embodiment, chemicals such as alkali, chelating, stabilizing and / or bleaching agents such as EDTA, DTPA, silicate, magnesium sulfate, hydrogen peroxide are used in step T2. In another embodiment, the temperature in the T2 phase is in the range of 70-210 ° C.

The released anionic agents may include, for example, galacturonic acid, glucuronic acid and 4-O-methylene glucuronic acid. The process of the present invention mainly reduces the amount of galacturonic acid.

In one embodiment, the alkali treatment step is an alkali pretreatment step before mechanical defibration at high temperature (CTMP defibration). In yet another embodiment, the alkali treatment step is an alkali pretreatment step prior to alkaline peroxide bleaching; prior to the MC step in the two-step MC-HC bleaching sequence or prior to a single HC step or as an MC step using a controlled temperature prior to the high temperature HC step.

'' Chemical pulp '(CTMP) is prepared by treating a lignocellulosic material, usually wood chips, with one or more chemical agents, which includes the steps of heating the material and separating the fibers mechanically. In the above combined operations involving heating, chemical treatment and fiber separation, chemical treatment using a controlled temperature Ti may be performed before, during or after fiber separation.

Generally, when preparing CTMP pulps, the yield, that is, the dry weight of the pulp relative to the dry weight of the starting material, is obtained in the range of 70-90%, typically 85-90%, and TMP pulps 85-95%, typically 90-95%.

'' Chemical pre-treatment 'generally means an operation during which a lignocellulose-containing material, usually chips, is treated with either a sul-10-hit or a sulphite-sodium hydroxide mixture at a temperature equal to or greater than 100 ° C at a saturation vapor pressure. Treatment with liquids containing mixtures of sodium hydroxide and hydrogen peroxide is typically carried out at 60-80 ° C. The chemical treatment potentially involves conventional vapor absorption of the lignocellulosic material material to facilitate infiltration of a solution containing the selected reagents, followed by a subsequent screw extraction step (s) to remove entrained air and promote chemical partitioning.

The temperature at which the treatment is carried out is generally not more than 200 ° C and is usually in the range of about 120 to 160 ° C. The treatment medium will initially have a pH in the range of 6 to 12.5.

The duration of the chemical pre-treatment is dependent on the choice of other process variables, but is usually not more than 1 hour.

Expressed as SO2, the amount of sulfite in the pretreatment is, for example, in the range of about 0.1-10%, most typically 0.5-3%, with oven-dry lignocellulosic material and sodium hydroxide 0-7%, depending on the species of wood and product and process requirements. The amount of Η202: η in the alkaline peroxide pretreatment may be in the range 0.5-12%, most typically 3-5%, and the amount of sodium hydroxide 0.5-10%, most typically 2-7%, depending on the type of wood and product and process requirements.

Certain chemical agents, for example complexing or sequestering agents such as diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), sodium silicate, and magnesium sulfate (magnesium sulfate), may be used in combination with alkaline sulfite or alkaline peroxide.

The prior art bleaching of TMP and / or CTMP pulps using hydrogen peroxide in an alkaline medium is typically carried out by adding about 0.5-10% hydrogen peroxide in the presence of about 1-10% sodium silicate solution at a pH of about 9-11 and about 40%. At a temperature of -100 ° C for about 0.5-2 hours at a consistency of about 10-30%. The bleaching bath may also contain certain additives, mainly one or more sequestering or complexing agents, such as DTPA.

Tower bleaching refers to bleaching that usually occurs at high consistency.

The 2-stage bleaching process, which recycles HC (high consistency) bleaching filtrate to 10 initial MC (medium consistency) steps, is typically used where high (> 80% ISO) brightness is required for bleaching targets. The temperature at the first contact of the bleaching liquor and pulp is at the same level as the temperature of the bleaching step, i.e., with a good margin above 60 ° C, typically between 70 ° C and 90 ° C.

Soak bleaching refers to bleaching at high material consistency in a pressed pulp at lower temperatures, usually 20-45 ° C and longer bleaching times than conventional tower bleaching.

Defibrator bleaching means bleaching that is performed during the defibration step by adding alkaline peroxide to the feed to either the primary refiner or the secondary refiner. This means that the temperature at the first contact of the bleaching liquor and pulp is usually very high, i.e. 100-160 ° C.

eXAMPLES

EXAMPLE 1: Color development of pectin under alkaline conditions at various temperatures Commercially available methylesterified pectin (1 mg / ml pectin, 94% methylesterified, 0.3 ml 1 M NaOH, 20-100 ° C, 30 min). From Figure 1, it can be seen how the decomposition of pectin under alkaline conditions at elevated temperatures (above 70 ° C) results in a more intensive formation of chromophores, resulting in severe darkening of the waters.

It can be seen from Figure 3 that the pectin chain break is a very rapid reaction even at low temperatures, in this case at 40 ° C. In just 20 seconds, the chain length has been reduced by 30%.

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Example 2. Release of pectins from "TMP" pre-treated at different temperatures

Hot pulp from spruce (Picea abies L.) was sampled at a Finnish pulp mill after a second stage refiner at a consistency of approximately 35% and stored at -24 ° C until used.

'' Pure 'TMP fibers were obtained in a Soxhlet extractor with hexane-acetone (9: 1 v / v) for 24 hours to remove lipophilic material. Water soluble substances (hemicelluloses and low molecular weight aromatic compounds) were removed by careful washing. The pre-extracted TMP was suspended in distilled water (pH 5.5) at 60 ° C with a consistency of 2% and stirred for 3 h with a blade stirrer (~ 200 rpm). The TMP suspension was filtered under vacuum in a Buchner funnel using a papermaking machine wire. To prevent the loss of fines, the filtrate was passed through the formed fiber mycelium twice. The TMP was resuspended in distilled water and the washing operations were repeated 5 times. The final filtrate had a TOC of 4 mg / L. The washed TMP was air dried and stored in the dark at + 4 ° C.

10 g o.d. (oven-dry) TMP in 95g of the suspension kept in polyethylene plastic bags was mixed thoroughly. All pulps were first lost for 3 hours at 70 ° C, after which their temperature was adjusted to the target value for the experiments.

The masses were first equilibrated at various temperatures (4 ° C, 20 ° C and 70 ° C) for 1 hour, after which NaOH was added (see Table 1). At 4 ° C and 20 ° C, the pretreated pulps were stationary for 2 and 1 hours, respectively, followed by raising the temperature in a water bath to 70 ° C. At 70 ° C, the pretreated pulp was placed directly in a water bath set at 70 ° C for 90 minutes (Figure 4).

Finally, the pulps were cooled in an ice bath to 20 ° C. After the final pH measurement, the pulps were acidified with an amount of 6% SO2-water 30 to give a pH of 5. Samples of pulp filtrates were taken for chemical analysis.

Figure 5 shows how Xyl and GalA are released into water after alkali treatment at different starting temperatures. The difference in GalA release between 20 ° C and 70 ° C is high, i.e. more than 100%, while the release of neutral xylans (defined as xylose monomers) is not increased by raising the treatment temperature. This is a clear proof that the initial temperature at which the alkali encounters the mass determines the rate of cleavage of the pectin chain.

table 1

Pretreatment Main treatment Heat-NaOH Time Heat-time Final pH neutral state (° C) (% mass (min) state (° C) (min) after pH conditioning) * at 20 ° C to 2 1 120 70 60 8.5__4.6 2 2 120 70 60 10.5 5 20 1 60 70 60 8.0 4.8 20 2 60 70 60 10.1 4.8 70 1 0 70 60 8.6 4.4 70 2 0 70 60 10.5__5.1 5 * 1 M NaOH temperature adjusted to specific treatment temperature

Example 3

Bleachability of TMP pretreated at different temperatures

The mass used in Example 3 was the same as that used in Example 2 except that in these experiments it was not extracted with hexane or thoroughly washed. However, some of the water-soluble solids (hemicelluloses and low molecular weight aromatic compounds) were removed by first diluting the pulp to 2%, mixing the pulp at 60 ° C for 1 hour, and thickening the pulp to 20% with a BUchner funnel. To retain fines, the first portion of the filtrate was recycled through a fiber blanket.

Washed TMP, DTPA (0.25%, based on dry weight) and MgSO 4 (0.05%) were mixed thoroughly in a polyethylene plastic bag and kept overnight at room temperature. The pulp was thoroughly mixed and divided into plastic bags containing 10 g of o.d. mass each. The pulps were treated in parallel for each pretreatment temperature test (2 ° C, 20 ° C and 70 ° C).

The treatment scheme corresponding to Example 2 is shown in Figure 6. 10 ml of cold 3% H 2 O 2 was added to the pretreated masses at 2 ° C, mixed and placed in 13 cold (0-2 ° C) ice baths for 1 hour. To the mixture was first added 3 ml of cold Na-silicate solution (0.1 g / ml), stirred in cold, then 2.5 ml or 5 ml of 1 M NaOH (also this was cold) was added, stirred well and held for 2 hours. At 0- 2 ° C. At 20 ° C, the pretreated pulps were treated in an analogous manner except that the chemicals were added at room temperature and the pulp was kept at 20 ° C for 1 hour, after which the temperature was raised to the target bleaching temperature of 70 ° C. At 70 ° C, the pretreated pulps were taken directly to the bleaching step after the addition of the corresponding chemicals.

All three sets of pulps were placed in a water bath set at 70 ° C for 90 minutes. The pulps were cooled to 20 ° C in an ice bath. After the final pH measurement, the pulps were acidified with an amount of 6% SO2 in water to a pH of 5, followed by forming sheets according to the ISO 5269-1979 conversion.

Figure 7 shows the percentage ISO ISO brightness of sheets from bleached TMP at different starting temperatures. At higher temperatures, the brightness is significantly reduced by about 1 ISO%.

Example 4. Bleaching Bleaching of Unwashed TMP Pretreated at Various Temperatures and Cation Consumption of Its Filtrates The mass used in Example 4 was the same as in Example 3. Some of the water soluble materials (hemicelluloses and low molecular weight aromatic compounds) were removed by mixing at 2% consistency. 2 hours. The mass was thickened to 20% with a Buchner funnel. The first portion of the filtrate was recycled through a fiber blanket to preserve fines.

The washed and filtered TMP was mixed with DTPA (0.25%) and MgSO 4 (0.05%) and kept overnight, then the mass was divided into plastic bags containing 10 g of o.d. mass.

The treatment scheme for some of the experiments in Example 4 is shown in Figure 8. The masses to be treated at '' low 'temperatures (30 ° C, 40 ° C, 50 ° C and 60 ° C) were pretreated at 80 ° C for 2 hours. The pulps intended to be treated at 'high' temperatures (70 ° C, 80 ° C and 90 ° C) were not preheated. These experiments were performed by adding NaOH and peroxide or alkali alone to the pulp. All other variables were kept the same.

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Each pulp was pre-heated at the desired temperature for 1 hour, then added with 10 ml of 3% H 2 O 2, followed by the rapid addition of 3 ml of Na-silicate (0.1 g / ml) and 2.5 ml of 1 M NaOH. , mixed thoroughly (chemicals added and blended for 5 min) and the suspension held for a further 5 min at pre-5 heating temperature (total ~ 10 min with alkali at preheating temperature). All sets of bags were placed in a water bath set at 70 ° C for 90 minutes.

All pulps were cooled to 20 ° C in an ice bath. After the final pH measurement, the pulps were acidified with an amount of 6% SO2-10 in water to a pH of 5, after which the filtrate was sampled and sheets formed.

Figure 9 shows the cation consumption of water with and without peroxide after alkaline treatment of TMP at different starting temperatures. At higher temperatures (above 50 ° C), especially with alkaline (no peroxide) treated samples, the release of "anionic debris" is significantly greater than 100%. In alkaline peroxide treated samples, the increase in cation consumption is not as striking as with alkaline treatment alone. because peroxide acts as an alkaline reducing buffer.

Figure 10 shows the ISO brightness of sheets made from bleached and alkali-treated TMP at different starting temperatures. The lower temperature in the first bleaching stage resulted in + 2% ISO brightness compared to the higher temperature used in the initial alkali treatment. This difference is very significant and important because the high brightness units of high brightness masses are very cost-inefficient for chemical consumption, COD load and bulk material consumption. in terms of.

Analyzes were performed using the following equipment and methods

Bleached pulp paper sheets were examined using the SCAN ISO brightness test.

The sugar composition of hemicelluloses and pectins was determined using methanolysis (2M HCl in dry methanol), followed by gas chromatography analysis of TMS derivatives corresponding to the sugar monomers formed (Sundberg et al. 1996). The samples were freeze-dried before methanolysis.

The cation consumption (CD) of TMP waters was determined by polyelectrolyte titration using 0.0005 N potassium polyvinyl sulfate (KVPS) as an anionic polymer on the Mutek particle charge detector 03. TMP water samples containing soluble and colloidal substances were combined with 0.0005 N polybrene directly in assay cuvettes. :with.

A pH meter Handylab pH 12 (Schott-Geräte GmbH, Mainz, Germany) combined with a pH electrode BlueLine 28 pH (pH 0-14 / -5-80 ° C / Ge) was used to monitor the pH of the aqueous solutions / suspensions during alkali treatment.

Claims (14)

1. A process for treating pectin-containing lignocellulosic raw materials in a high yield pulping process using one or more processing steps under alkaline conditions, characterized in that the alkaline chemicals are used in a low temperature treatment step (T-ι), meaning that the alkali is first contacted with the material at one or more subsequent treatment steps at the same or higher temperature (T2) 2. Förfarande enligt patentkrav 1, kännetecknat av att reactionstemperaturen i; T o 70 ° C Ellera slurry, 60 ° C in french flask. 25 Process according to Claim 1, characterized in that the reaction temperature in Ti is at or below 70 ° C, preferably below 60 ° C. 3. Förfarande enligt patentkrav 1 eller 2, kännetecknat av att det alkali be-handlingsskedet utförs mechanical defibrering eller före et eller flera efterföljande alkaline blekningsskeden. 30 4. The patent application of the Förfarande enligt Face to the Föregäende, the kännetecknat av att pektinerna i det behandlade materialer and methylförestrade. Method according to Claim 1 or 2, characterized in that the alkali treatment step is carried out before the mechanical defibration or the subsequent alkali bleaching step (s). Process according to any one of the preceding claims, characterized in that the pectins of the material to be treated are methylesterified. 5. Förfarande enligt patentkrav 4, kännetecknat av att methylförestringsgraden 20-100%, definierat som percenten av galakturoniska enheter innehällande en methylesterggupp, företrädesvis 50-70%. 5 6. Förfarande enligt nägot av föregäende patentkrav, kännetecknat av att det pectininnehällande junk material, sommer barrträd eller lövträd eller deras kombinationer, kluvet lignocellulosarämaterial, säsom splintat trä, hackad halke. 10 7. Förfarande enligt vilket som Heist av föregaende patentkrav, kännetecknat av att such alkalis härstammar frän hydroxider, carbonater eller sulfiter, förretädesvis sodium, calcium, ammonium eller magnesium hydroxy, carbonater eller sulfiter, eller kombination. 15 8. Förfarande enligt vilket som Heist av föregäende patentkrav, kännetecknat av att i skede Ti tillförs ocksä andra chemikalier säsom kelaterande, stabiliserande och / eller blekande medel, företrädesvis peroxygener. Process according to Claim 4, characterized in that the degree of methyl esterification is 20 to 100%, determined as a percentage of galacturon units containing one methyl ester group, preferably 50 to 70%. Method according to any one of the preceding claims, characterized in that the pectin-containing raw material is wood, such as coniferous or deciduous wood or combinations thereof, chopped lignocellulosic raw material, such as; J wood chips, straw, pulp, or high yield pulp. A process according to any one of the preceding claims, characterized in that said alkali source is derived from hydroxides, carbonates or sulphites, preferably sodium, calcium, ammonium or magnesium hydroxides, carbonates or sulphites, or combinations thereof. Process according to any one of the preceding claims, characterized in that other chemicals such as chelating, stabilizing and / or bleaching agents, preferably peracid, are also used in step Ti. 9. Förfarande enligt vilket som Heist av föregäende patentkrav, kännetecknat 20 av att alkalisatsen in an interval of 0.1-10% (v / v) av det pectininnehällande materialets torrvikt. Method according to any one of the preceding claims, characterized in that the dose of alkali is in the range of 0.1 to 10% (w / w) of the pectin-containing material, expressed on a dry basis. 10. Förfarande enligt vilket som Heist av föregäende patentkrav, kännetecknat av att behandlingstiden av Ti in inom interval 1 second account 24 timmar. '25 Method according to any one of the preceding claims, characterized in that the treatment time of T-i is in the range of 1 second to 24 hours. 11. Förfarande enligt vilket som Heist av föregäende patentkrav, kännetecknat av att i skede T2 tillförs chemikalier säsom alkali, chelaterand, stabilizer och / eller blekande medel. 30 12. Förfarande enligt vilket som Heist av föregäende patentkrav, kännetecknat av att tempuren i skede T2 within a range of 70-210 ° C. Process according to any one of the preceding claims, characterized in that chemicals such as alkali, chelating, stabilizing and / or bleaching agents are used in step T2. Process according to any one of the preceding claims, characterized in that the temperature in step T2 is in the range of 70 to 210 ° C. 13. Massa som erhallits med förfarandet enligt vilket som Heist av föregäende patentkrav. 35 A pulp obtained by a method according to any one of the preceding claims. Paper, cardboard or tissue obtained from a pulp according to claim 13. 15 1. Förfarande för att behandla lignocellulosarämaterial som innehälier pektin i en defibreringsprocess med högt utbyte med utnyttjande av et eller flera behand-lingsskeden under alkaline förhällanden, kännetecknat av att alkaline chemistre (lags), vid den point; / där alkali för första gängen business contact med materialet som innehälier pektin, före 20 et eller flera efterföljande behandlingsskeden vid samma eller högre Temperature (T2). 14. Papper, cardboard eller tissuepapper framställd av pulp enligt patentkrav 13.