CA2167605A1 - Method for ozone bleaching paper pulp - Google Patents

Abstract

A method for ozone bleaching unbleached chemical paper pulp in a single ozone stage and in the presence of a tertiary alcohol including four to eight carbon atoms which is fed into the reaction medium at a temperature of - 5 DEG C to 80 DEG C prior to the actual ozone treatment stage, whereby the gas-liquid transfer, the exchange potentiality, the lignin oxidation selectivity and the ozone efficiency are improved, and the consitency of the treated pulp undergoing ozone treatment is between 6 and 60 %.

Description

W095 / 034 ~ 2 ~ 6 7 ~ ~ 5 PCT ~ 4/00910 BLAN ~ TM ~ NT PROCESS FOR PAPER PULP
BY THE OZONE
The present invention relates to a method of bleaching of paper pulp providing improved delignification stage performance involves in laundering sequences.

It is known in the prior art ~ ue the bleaching of chemical paper pulp obtained by baking of lignocellulosic materials, is carried out by means a sequence of delignifying treatment steps, using oxidizing chemicals. The first step in a classic whitening sequence is traditionally made by treating the unbleached dough with chlorine in an acid medium or by a chlorine-dioxide combination chlorine, so as to react with the residual lignin of the dough, to give chloro-lignins. These last can be extracted from the dough by solubilization in alkaline medium during a subsequent processing step.
The whitening sequence involves a series of stages corresponding to different chemical treatments can be coded as follows:
25 C Chlorination Reaction with chlorine elementary in the middle acid E Alkaline extraction Dissolution of products reaction using NaOH

Eo Oxidizing alkaline extraction Alkaline extraction in presence of oxygen D Chlorine dioxide Reaction with ClO2

2 1 ~ 7 ~ ~ 5 ~ rr ~ r ~ t -~ f 1 ~ r 2 -r, rr r ~ en CD Chlorine / chlorine dioxide Reaction with mixtures of the two compounds O Oxygen Reaction with ~ oxygen elementary in the middle alkaline H Hypochlorite Reaction with hypo-chlorite solution alkaline P Peroxide Reaction with a peroxide in an alkaline environment Z Ozone Reaction with ozone .

The blan ~ .h; m ~ nt sequences commonly used artwork so far include five to six stages among which molecular chlorine treatment intervenes in the first stage. The most common are: CEHDED and CEDED (for a more detailed description complete conventional bl ~ nch processes; ment can be refer to GA SMOOK, H ~ n ~ hook for plllp ~ n ~ p ~ p ~ .r T ~ .hnolo ~ i ~ t ~, 198 ~., 153-173 TAPPT, Atl ~ nt ~ GA).

These bleaching processes; m ~ nt provide pasta whose whiteness (Bl), the Kapa index (IK), as well that the degree of polymerization (DP) is satisfactory at industrial plan.

To date, existing or current legislation promulgation put the paper industries in remains to no longer use chlorine reagents for this type of operation in order to reduce any risk of pollution due to unwanted byproducts in effluents.
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W095 / 034 ~ 216 7 ~ O ~ PCT ~ 4/00910 -_ 3 Certain byproducts of bleaching using chlorine or its derivatives induce toxic compounds (AOX), some of which may be mutagens, carcinogens, bioaccumulative. These byproducts (AOX) come from the reaction of chlorine or derivatives chlorinated with organic matter from the degradation of lignin.

10In a first phase, he is known in the state prior art that the paper industries have attempted to limit the use of chlorine or its derivatives by replacing, at least partially, the first treatment step using chlorine or combination chlorine chlorine dioxide, by a pre-delignification using oxygen in an alkaline medium.

However, oxygen has been shown to be an agent delignifying less selective than elemental chlorine. In conventional delignification methods at oxygen, the reduction in the Kappa index remains limited because it is accompanied by a significant attack of the fibers cellulosic. This is why the pre-treatment of the dough oxygen is usually followed by a bleaching stage with chlorine to obtain a completely bleached pulp, using a lower amount of chlorine. This is how that the amount of AOX produced per ton of dough could be decreased significantly. This effort, although substantial, is not sufficient to bring these processes into line with standards or prescriptions issued by major countries industrialized.

For several years, to avoid the use chlorinated bleaching agents, many research are trying to develop sequences using preferably oxygenated reagents alone or in combination with a reduced acceptable chlorine oxidizer (the chlorine dioxide). The pasta thus produced cannot W095 / 03 ~; PCTn ~ 4/00910 21 ~ 76 ~ 5 ~ =

claim the label "totally chlorine free" (TCF), since is still used in these treatments, chlorine.

It is also known in the prior state of the technique of bleaching chemical pulp (kraft or sulfite) using sequences using only reagents oxygen ~ born. Oxygenated products conventionally used include oxygen, ozone, hydrogen peroxide, put implemented in combined sequences, i.e. in stages successive without prejudging the relative position of one oxidation steps.

Due to its oxidizing properties ozone appears to be the reagent for delignification ideal for bleaching ligno- fibers cellulosics, even if until today its price relatively high has limited the development of processes industrial.
Conventionally, there are described in the art anterior, bleaching sequences of the OZEP, OZP type, ZOP ... But, in this case, either the final dough lacks whiteness, i.e. its degree of polymerization reaches unacceptable levels, resulting in decreases in yield or drops in mechanical characteristics.

This phenomenon is due in particular to the non-ozone selectivity, which although rapidly attacking woody structures, correlatively degrades the structures cellulosic or hemicellulosic, which materializes the significant reduction in the degree of polymerization. Otherwise, ozone is extremely sensitive to operating conditions such as pH and temperature. Its chemical stability implies perfect control of the ozonation parameters.

According to the literature, the ozone attack on cellulose is mainly caused by radicals W095 / 03 ~ 21 ~ 7 6 ~ 5 PCT ~ 94/00910 formed during the oxidation of lignin or from the decomposition of ozone in the reaction medium.

Although there is no rule formalizing the relative position of stages involving reagents oxygenated in the bleaching sequences it's generally accepted that these sequences begin with a stage oxygan whose development has been the subject of many publications. Generally, it is also accepted that the ozone stage follows oxygen stage with or without stage washing type, alkaline extraction or washing type in the presence of a sequestrant or a complexing agent.

The use of a sequestrant or a complexing agent aims to inhibit the action of metal cations contained in the paste, said metal cations possibly induce, in the presence of certain reagents, radicals free whose chemical action is well known at the level of parasitic attacks of cellulose and hemicelluloses.
If you want to properly whiten a dough unbleached chemical using only reagents oxygenated it is necessary to have specific agents protective type or transfer agents likely to protect cellulose and hemicelluloses and / or make the more selective the lignin oxidation reactions.

This type of protective agent or transfer agent must make it possible to avoid and control the drastic drop the degree of polymerization during said stages of white; ~ ent. Simultaneously with the use of such additives, operating conditions (choice of physical and chemicals, etc.) must be in perfect adequacy in order to to optimize the result to be obtained.
In the prior art, certain organic reagents have been tested with more or less success: these are in particular products such as W095 / 03 ~ PCTn ~ 4/00910 2 ~ 7 ~

acetone, acetic acid, formic acid, acid oxalic, methyl acetate, acetic anhydride, nitromethane, methanol, ethanol, methyl ethyl ketone, dimethylformamide, dimethyl sulfoxide, propan-2-ol .... (see N. Liebergott, B Van Lierop, A.Skothos, Tap ~ i Journal January 1992, 145-152 and February 1992, 117-124 as well that MV Byrd Jr., JS Gratzl, RP Singh, TaPpi Journal March 1992, 207-213).

US-A-4 229 252 reports the use, ~ when ozone bleaching stage, alcohols introduced in small amount in the reaction medium, this in small consistency, i.e. for 0.01 to 4.9 ~ of dry matter, suspension in water.
Without taking into account an initial analysis of results obtained in the prior art, it is possible to make a number of comments and including clarifying that many of these products cannot be implemented only according to a particular method of treatment.

It is known that the methods of bleaching pulp ~ paper can be used in three ways different areas of consistency:

- low consistency (FC), describes a stage of bleaching in which the mass of dry matter in suspension in water is industrially between 3 and 5% (US-A-4,229,252 for example).
- the medium consistency (MC), qualifies a suspension with dry matter content industrially between 6 and 20% by mass.
- the high consistency (HC), characterizes a suspension with a dry matter content industrially between 20 and 60% by mass.

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The additives used in the prior state of the technical, were preferably for one, or even two, consist ~ n ~ e ~ defined above, consistencies where their action proved to be preponderant. It is generally low and medium consistencies.

The Applicant has discovered that it is possible to use ozone to carry out sequences of bleaching in the presence of carefully selected additives, and under operating conditions such as the fall of the degree of polymerization is limited, the value obtained being very little decrease compared to previous results obtained.

Additives used in the process according to the invention as well as the physico-chemical parameters of the ozonation reaction ~ are chosen so as to allow to whiten a dough significantly using essentially an ozone stage.
Consequently, the invention relates to a method of bleaching of unbleached chemical pulp of the ozone aid, characterized in that it does not use an ozone stage exclusively, in the presence of an alcohol tertiary, comprising from four to eight carbon atoms which is introduced into the reaction medium maintained at a temperature between -5 C and 80C, prior to proper ozonation stage, in order to improve the gas-liquid transfer, exchange potential, selectivity of lignin oxidation and the effectiveness of ozone, the consistency of the dough subjected to ozonation being between 6 and 60%.

According to the present invention, said additive is a alcohol having from four to eight carbon atoms, preferably four carbon atoms.

SHEET ME ~ FIEE
IPEA / EP

21676 ~) 5 r ~ ~ r ~ rr rr ~ r ~ r -r ~ rrrrr _ 8 .., According to an embodiment of the method according to the invention, said alcohol is a tertiary alcohol having four to six carbon atoms.

According to the invention, said additive is introduced according to a mass percentage, compared to dry dough, between 0.01 and 300%, preferably between 0.1 and 100 % and better between 1 and 10%.

Experience shows that temperature has a predominant influence on the selectivity of the reaction in the presence of additives as will be seen below during of the presentation of the examples of implementation. According to the invention, the temperature of the reaction medium during ozonation is between - 5C and + 80C, from preferably between 0C and 60C and better between 0C and 25C.

The addition, according to the invention of small quantities of an oxygenated organic product improves significant the selectivity of the delignification stage of the ozone paper pulp. In addition, if one operates in-below room temperature, in the presence of such additive, this delignification becomes very effective.

To date, it has never been shown to be possible to whiten a chemical paste by not using exclusively an ozone stage, without degrading considerably the dough thus treated.

In order to demonstrate the surprising effects by its invention, the applicant has carried out tests in placing themselves in extreme conditions which will not be those of an industrial operation, namely a almost complete delignification of a chemical paste as well as its bleaching to acceptable whiteness levels in using only an ozone stage. If the modes procedures of the process according to the invention, as well as the relative products, are conventionally used after a MOD ~ IFIEE SHEET
IPEA / EP

W095 / 034 ~ 21 ~ ~ 6 0 ~ PCT ~ 4/00910 .

oxygen stage, the results will only be better and will be correlatively accompanied by a reduction in the amount of ozone required for this implementation artwork.

We have given below, by way of illustration and without no limiting a number of examples of implementation of the method according to the invention, the reagents and / or the physico-chemical parameters of the reactions being given either under direct operating conditions, or under conditions of oxygen pre-treatment of the dough paper. The examples marked R do not conform to the invention and they are given by way of reference.
.
During this talk, we will refer to the curves given in annex to this description and for which we will give below all explanations required.

Most of the trials were conducted from an unbleached kraft paste with no treatment prior and characterized by:

- a Kappa index (IK) measured according to the NF standard ISO 302-1981 (F) of: 40.2 - a degree of polymerization (DP) measured according to the TAPPI T 230 om-82 standard from: 1950 _ a degree of whiteness (Bl) measured according to the standard NF Q 50-012 of: 28.3.
During the tests, including the examples below report we generally followed the operating mode below with regard to the stages of ozonation.

- A quantity of dry p ~ te is put to soak in an aqueous solution of sulfuric acid of pH 3 (acid pretreatment).

6 7 6 ~) S rrrrt - ~ - r - After disintegration of the dough according to standard ACPP C-lOP, the dough is separated from its aqueous medium and then washed with water. -- The consistency of said dough is adjusted to 3%
by mass of dry paste in the aqueous medium.
- The suspension thus obtained is ozonated in now constant the temperature of the reaction medium depending on the test chosen, the ozone load introduced, that is to say the amount of ozone introduced into the medium reaction being equal to 40 kg O3 / t of dry paste.
- After reaction and taking into account the material balance performed during this operation, it is possible to determine the actual pulp treatment rate (TT O3) corresponding to the mass of ozone that actually reacted with the dough, r ~ n ~ to the mass of dry dough present during the reaction. The treatment rate is expressed in kg of ozone per tonne of dry pulp.

- After reaction the dough treated with ozone is separated from the aqueous reaction medium, washed and then subjected in tests to determine the Kappa index, the degree of polym ~ risation and the degree of bl ~ nche-lr.
- Depending on the results obtained during these tests it is possible to determine two ratios significant to materialize the relevance of results obtained. These are the following reports:

l / t ~ llx ~ tr ~ t ~ m ~ nt en O ~ ie TTO3 / ~ IK
change in the Kappa index This report representing the mass of ozone necessary to delignify a ton of dough, one point of Kappa index. The lower the value of this ratio, the better the use of ozone, so the efficiency of ozone.
352 ~ / ne ~ r ~ ~ e poly ~ ri ~ tion either DP / IK
Kappa index SHEET l \ AOQIFIEE
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This report directly measures the selectivity of the delignification since one wishes to maintain a degree of highest possible polymerization by obtaining correlatively the lowest possible Kappa index.
The higher this ratio, the better the selectivity of ozone.

In table 1 below the unbleached kraft paste used has a Kappa index of 40.2 and a degree of polymerization of 1950.

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The results that were recorded in this table 1 highlight one of the major facts - discovered by the plaintiff which is the influence of the temperature of the reaction medium on the delignification and bleaching when using a carefully chosen additive. This additive designated by the reference A in this table 1 is 2-methyl-propan-2-ol.

If we compare curves 1, given in the appendix, representative of the ozone treatment rate, i.e.
the amount of ozone actually used during a bleaching reaction, depending on the temperature, with and without additive A, we observe an almost treatment rate constant as a function of the temperature in the absence of additive, whereas in the presence of additive, one obtains a curve where the treatment rate is slightly decreasing with temperature in the range ranging from 0C to 25C, followed by a second portion of different slope curve with more decay accentuated treatment rate between 25C and 60C. What whatever the temperature, the treatment rate in the presence of additive A remains higher ~ that obtained in the absence additive.
The difference in treatment rate is all the more more pronounced than the temperature is low.

In order to verify that the phenomenon observed was not not due to consumption of ozone by reagent A, we have demonstrated that direct ozonation of this product as well as ozonization of dough in the presence of this product, did not lead not to consumption of said reagent A by the injected ozone.

As the reagent is not consumed, the increase in treatment rate, i.e. ozone actually used during the reaction, is explained by a better transfer of ozone gas to the aqueous phase and after : ~;
W095 / 03 ~ - ~ `PCT ~ 4/00910 21676 ~ 5 diffusion of this trans ozone, of better fiber accessibility by dissolved ozone. This phenomenon is corroborated by the observation of the size of the bubbles ozone gas in the reaction medium, size which is S strong decrease compared to bubbling in an environment aqueous reputed to be pure. The decrease in the size of the bubbles ozone gas causes an increase in area interfacial exchange and consequently a better transfer from the gas phase to the liquid phase, all conditions being equal elsewhere.

The transfer being improved, more masses significant ozone are present in the environment reaction, the exchange potential increases simultaneously and the accessibility of the fibers is found facilitated.

This phenomenon is highlighted by curve 2 of TT 03 / ~ IK, depending on the temperature.
This curve 2 shows that this ratio TT 03 / ~ IK
in the presence of reagent A, presents a large portion increasing linear with temperature and in all case, systematically lower in absolute value than the same trace curve without additive of the reaction medium.

It has been observed that the Kappa index obtained after ozonation in the presence of reagent A was systematically lower than that obtained after ozonation in the same operating conditions, excluding the presence of reagent A.
in other words, the decrease in the Kappa index is more fast in the presence of the reagent A ~ except for the presence of this reagent A. This leads to the conclusion that the use of this reagent A allows better delignification for the same amount of ozone used.

Correlatively it was also observed that the variation of the degree of polymerization (~ DP = DPo - DP) W095 / 034 ~ ~ 6 ~ PCTn ~ 94/00910 corresponding to the decrease in the degree of polymerization during the ozonation phase, reduced to the treatment rate:
(~ DP / TT 03) was systematically better in the case of ozonation in the presence of additive A, compared to the same ozonation result without this additive A.

Curve 3 representative of the ratio ~ DP / TT 03 in the presence of additive, depending on the temperature, has a large linear part up to 40C while the same curve without additive has an increasing part in temperature function. So we see that a ozonation without additives induces a drop in the degree of polymerization greater than ozonation in the presence additive for the same ozone treatment rate.
This phenomenon demonstrates the selectivity provided by reagent A since the ozone injected preferentially goes react with woody structures rather than with cellulosic or hemicellulosic structures. This selectivity can be convincingly materialized by representing the variation in the degree of polymerization brought back has the Kappa index (DP / IK) as a function of temperature.
This is what is observed on curve 4 given in the appendix.

25The study of this curve 4 provides the following information:

The DP / IK report relating to ozonation without additive A is materialized by a straight line whatever the temperature. We can therefore conclude that this DP / IK ratio is almost constant, with very slight deterioration for high temperatures. On the other hand, the representation of this same report in the presence of reagent A shows, surprisingly, a decreasing monotonic curve in temperature function in any case greater than the previous curve and in particular for the means and - low temperatures where the difference can reach approximately 60 points.

~ rrrrr ~ rr ~ r 2 1 6 7 6 ~ 5 16 I rrr ~ r This observation is linked to a slight decrease significant degree of polymerization for high decrease in the Kappa index. This demonstrates in a way formal selectivity induced by the additive A during a ozonation sequence, this being carried out in drastic conditions since the ozonation was operated on an unbleached kraft paste, without prior stage of oxygen delignification. So far, none known result did not allow to highlight such possibility.

The results thus obtained by the implementation of the process according to the invention are in formal contradiction with those mentioned by Meredith in US-A 4,229,252, which observed independence of temperature from the effectiveness of delignification.

Table 2 below collates the data related to the different parameters significant and their variations according to the rate of ozone treatment.

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SUBSTITUTE SHEET (RULE 26) W095 / 03 ~ PCT ~ 94/00910 ~ i ~ 76 ~

The curves to which we refer below have been traced from the experimental elements contained in this table 2.

Curve 5 represents the variations in the rate of ozone treatment (TT o3) depending on the charge ozone introduced into the reaction medium.

It should be remembered that the processing rate in ozone is the quantity actually used for- a bleaching reaction. This amount is calculated at using mass balances carried out during the test. The ozone load is the quantity of raw ozone introduced into the reaction medium.
This curve 5 represents the treatment rate in ozone depending on the ozone load for different temperatures (0C and 25C), for ozonation in the presence of additive A (2-methyl-propan-2-ol) or for ozonation performed without this additive A.

These results show two phenomena remarkable: the first relates to the ozonation of the dough in the presence of additive A where it is found that the two curves plotted for the respective temperatures of 0C and 25C are practically superimposed, however that the curves drawn without additive A are divergent in load function for the two temperatures concerned (0C and 25C).
The quasi superposition of the two curves at O and 25C for ozonation in the presence of the additive A demonstrates that the ozonation efficiency as well as the transfer are independent of temperature when using the reagent A in the temperature range between 0C and 25C. These values are to be compared with the portion of the curve 3 between 0C and 25C.

W095 / 034 ~ 2 ~ 6 ~ ~ ~ 5 PCT ~ 4/00910 -~. . . .

Regarding the ozonation tests in the absence of an additive, the divergence of the curves is noted.
oC and 25C, depending on the load applied. This demonstrates the influence of temperature when do not use additives. The curve at 0C when not used not additive A, has a better coefficient of ozone use, therefore a better yield than the curve at 25C without reaching the values of the two almost superimposed curves when using additive A.
As an example, we can see that for a same treatment rate (about 30 kg / t of dough) the load in ozone represents 40 kg of ozone per tonne of pulp in the in the case of a temperature of 0C or 25C, in the presence of the reagent A, whereas for the same value of the treatment rate, it it is necessary to introduce, in the absence of additive, 90 kg of ozone per tonne of dough at 0C and 125 kg of ozone per tonne from p ~ te to 25C.

The presence of additive A in the medium reaction induces a very significant improvement in ozonation efficiency, resulting in savings in ozonated reagent during whitening sequences.

As an indication, for the processing rate chosen in the example above, the yields are as follows:

- for ooc or 25OC, in the presence of the additive A, yield = 75%
- for 0C and without additive, yield = 33%
- for 25C and without additive, yield = 24%.

For a temperature of 25C, if we compare the yields obtained in the presence of additive A and the yields obtained in the absence of these additives, we go account that yields are multiplied by a factor of 3.

2 1 S 7 ~ ~ ~ rrrrr r Curve 6 gives the variation of the Kappa index (~ IK = IKo ~ IK), depending on the processing rate in ozone for temperatures of o ~ C and 2SC, in the presence and in the absence of additive A.
, ...
Examination of curve 6, for a temperature of O ~ C and in the presence of the additive A shows a growth of delignification materialized by the difference in Kappa index according to the treatment rate.
The same curve at O ~ C plotted from the points o ~ kept without the presence of the additive A
~ aisse of the Kappa index, lower than that o ~ served previously. The selectivity of the additive A used is 15 also highlighted by this representation.

The curve plotted at 25C, in the presence of the additive A, is located below the previous one, while remaining superior to the court ~ eo ~ held at 0C in the absence ~ of 20 Additive A.

The curve plotted from the points obtained in the absence of additive A and at 25C is the worst curves. It is located below the corresponding curve 25 to 0C.

Cour ~ e 6 leads to conclusions following: in the presence of additive A, that the temperature either from O ~ C or 25C, we get a better 30 deligni ~ ication, therefore a more significant drop in the index Xappa that when working under the same conditions and for the same temperatures, in the absence of the additive A.
selectivity provided by the additive A, whatever the temperature is thus demonstrated.
Curve 7 represents the variation of the index of polymerization (DP) as a function of the Kappa index (IK) for temperatures of 0 ° C and 25 ~ C, for ozonation MO ~ FIEE SHEET
IPEA / EP

21 ~ 76 ~
W095t034 ~ PCT ~ 4/00910 carried out in the presence of additive A or without the presence of this additive.

The two curves thus obtained at ooc are S substantially parallel but the interesting point is in terms of ozone use and the Kappa index that it is possible to reach for ozone loads eminently different.

On the representative curve of ozonation outside presence of additive A, at 0C, for an ozone load of 140 kg / t and for a treatment rate of 57.4 kg / t, it is possible to obtain a Kappa index of 16.3 while on the curve representative of the points obtained during a ozonation in the presence of additive A and at 0C, for a theoretical ozone load of 80 kg / t and at a rate of treatment of 62.16 kgO3 / t we obtain a Kappa index of 8, this while maintaining a degree of polymerization at a excellent value close to 1360. This curve shows clearly the effectiveness of reagent A with regard to the ozonation efficiency and excellent selectivity given to oxidation by this reagent A, during a stage of delignification, since for a treatment rate substantially identical the difference in delignification (IK) is 8.3 points.

The demonstration is even more convincing at 25C, since curve 7 given in the appendix shows that a delignification with ozone alone, at this temperature, not allow the Kappa index to drop below 28.9 whereas the same ozonation sequence, practiced at 25C, in presence of additive A, achieves a Kappa index of 9.1 and a degree of polymerization of 1449. The selectivity of the reaction in the presence of additive A is, in this case, highlighted since for a Kappa index significantly reduced the degree of polymerization retains an exceptionally high value.

W095 / 03 ~ PCT ~ 94/00910 21 ~ 7605 22 Curve 8 given in the appendix represents the report DP / IR, depending on the ozone treatment rate (TT O3).
We note that an ozonation, conducted without the presence of the additive A and at 0C induces a representative curve increasing as a function of the ozone treatment rate with a maximum of DP / IK = 96.69 for a rate of ozone treatment of 57.4 then ~ ue the same sequence conduct in the presence of additive A leads to the result next: DP / IK = 170.5 for an ozone treatment rate 62.16.
This clearly demonstrates the selectivity of the reagent A during an ozonation sequence, for a temperature of 0C reaction medium.

If we make the same comparisons for a temperature of the reaction medium of 25C, it is found that the representative curve provides a report DP / IK = 64.12 for a treatment rate of 34.72 while the same sequence carried out in the presence of reagent A allows obtain a ~ P / IK ratio of 159.12 for a rate of treatment of 61.84.

Analysis of the results thus materialized clearly the selectivity brought by the reagent At whatever temperature in the range of temperature between 0 and 25C.

Curve 9 gives the representation of the evolution whiteness as a function of the ozone treatment rate.
The comparison between the curves drawn at 0C for a ozonation in the absence of additive A and ozonation at the same temperature in the presence of this additive A, made very significant whiteness differences appear for substantially identical treatment rates.
For a treatment rate of 57.4 in the absence of additive A, it is possible to achieve a whiteness of 46.4 whereas during an ozonation sequence in the presence 21 ~ 75 ~ 5 WOgS / 03 ~ PCTn ~ 4/00910 of additive A and at 0C, for an ozone treatment rate also close to 62.16 it is possible to reach a whiteness of 71.3.

The difference in whiteness for a rate of substantially identical treatment is 24.9 points in favor of an ozonation sequence using the additive A. The same ozonation sequence without the presence of this additive A
and driving at 25C achieves a whiteness of 35.3 for an ozone treatment rate of 34.72 and a whiteness of around 60 for a treatment rate of 61.84. In the case of a temperature of the reaction medium 25C the difference in whiteness also remains significant, although the absolute values are lower than those obtained at 0C.

This demonstrates that the additive A, promoting the delignification while maintaining a degree of polymerization suitable, achieves high degrees of whiteness in a single ozonation stage, this additive A constituting a agent that promotes selectivity and improved whiteness.

Curve 10 represents the variation in the degree of whiteness depending on the treatment rate reduced to the Kappa index variation (TT 03 / IKo ~ IK) and this, for two tested temperatures of 0C and 25C.

An ozonation sequence conducted at 0C in the absence of the additive A shows a variation of the degree of whiteness as a function of the ratio (TT 03 / IKo ~ IK) with a maximum of 46.4 in whiteness for a (TT 03 / IRo ~ IK) 2.4. The same ozonation sequence, conducted at 0C in the presence of the additive A, makes it possible to obtain a whiteness of 71.3 for a (TT 03 / IKo ~ IK) of 1.93.

The difference in the variation of the degree of whiteness is very important when we compare these two 2 ~ 6 7 ~; ~ 5 - ~ ~ ~ rr - rrr - r ~ rr 24 re ~ rr. r .. ~ rr curves and, in particular, for the same (TT 03 / IK0 - IK) the variation in the degree of whiteness is 24.9 points in favor of the ozonation sequence in the presence of the additive AT.
`, If we compare the curves materializing a ozonation at 25C, in the absence of additive A, at the curve plotted for the same temperature in the presence of additive A
the following significant points are obtained: at 25C, in the absence of additive A and for a (TT 03 / IKo - IK) of

3, l, the degree of whiteness is 35.3 while for a sequence carried out in the presence of the additive A and at the temperature of 25C, it is possible to obtain a degree of whiteness of 60.9 for a (TT 03 / IKo - IK) of 1.99.
If we compare the increase in the degree of whiteness for the same (TT 03 / IKo - IK), the difference is is 25.6 in favor of the curve plotted for a ozonation sequence in the presence of additive A. This representation demonstrates that whatever the temperature reaction medium between 0C and 25C, the degree whiteness achieved is very much higher when additive A is used, as it is in the absence of this additive.
Correlatively it appears that these rates of whiteness are obtained for (TT 03 / IKo - IK) always lower than those obtained in the absence of additive A.
The selectivity and whitening properties of additive A are highlighted by this representation. The phenomenon is all the more preponderant that it is impossible in the absence of the additive A of conduct an extensive delignification of the treated dough.
In all cases, the use of additive A allows a much more delignification with degrees of higher whiteness and better efficiency of ozone introduced into the reaction medium.

SHEET ~ / IO ~ FIEE
IPEA / EP

r ~ ~ rr ~ ~ r 2 1 6 ~ 7 6 ~ 5 ~ r Having discovered, surprisingly, that the addition of the additive A (2-methyl-propan-2-ol) to the reaction medium during the bleaching sequences by ozone provided interesting properties such as described above, the Applicant has compared this additive A
to other generic reagents of the same type.

Reagent A (2-methyl-propan-2-ol) being part tertiary alcohols, it was interesting to compare it other primary, secondary and tertiary, chain l; ne ~ 1st or branched to verify if these different alcohols had the same properties ~

To do this, the plaintiff conducted a certain number of investigations whose content is formalized in Table 3 below:
, For your convenience, the different types spirits have been identified in this table 3 by letters capital letters. The n ~ m ~ nc ~ ature thus assigned is given below after.

MO ~ FIEE SHEET
IP ~ AIEP

21 ~ 7 6 ~ 5 ~ PCT ~ R94 / 00910 DESIGNATION

B butan-l-ol CH3-CH2-CH2-cH2-OH
C butan-2-ol CH3 CH2 CIH OH

A 2-methyl-propan-2-ol CH3-C-OH
. CH3 D 2-methyl-butan-2-ol CH3-CH2-f-OH

E 2-methyl-pentan-2-ol CH3-CH2-CH2-C-OH

F 2,3-dimethyl-butan-2-ol CH3-CH -'- OH

~ H3 CH3 G 3,7-dimethyl-octan-3-ol CH3-CH-CH2-CH2-CH2-C-OH

SUBSTITUTE SHEET (RULE 26) WO 95/03448 21 ~ 7 6 0 S PCT / FR94 / 00910 - t ~ 0 ~ D tD CO U ~ N ~
.D _ O ~ 9 0 ~ i 1 ~ 0 _ _ ~ D

-----------____ y O ~ D ~ ~ _ ~ ~ - ~ 0 0 ~ 0 a ~ ~ 9 ~ L ~

O ~ l O t ~ ~ 1 ~ 0 1 ~ t ~ .l 0 ~ D ~ r) N
~ _ - ______________ N ~ ~ _ r ~
y ON 0 0 ~ 0 0 ~) N ~ ~ U ') _ NN 11') ~ ~ N _ _ _ _ t ~ t ~ _ NNNNN
~ J
~) ~ L t ~ .l N t ~ l ~ DN ~ t ~ 0 ~ N ~ t ~ l ~ - ~ ~ 1 ~ O ~ N ~ D ~ N
1-- ~) - - t ~ JOO 0 0 - - t`J t ~ o ~) 0 0 ~ i 1-- - _ t ~) ~ ~ ~ ~ N - - ~ NNNNN

~, i-- 0 0 0 0 0 0 0 0 ~ l N ~ JNN t ~ J

~! ~ ~ - - - - - - - - - - - -: ~, oooooo ....... oooooo

4., e ~ ~ m ~ s: n UJ LL ~. m D ~
~ ooooooooooooooo ~ e - N ~ ~ Y ') ~ 1 ~ 1 C5 ~ 0 - N ~ ~ UJ-c ~ - c ~ c ~ c ~ l SUBSTITUTE SHEET (RULE 26) W095 / 034 ~. ~ PCT ~ 94/00910 ....
~ 676 ~ S

The choice of these alcohols was dictated by many working hypotheses which are as follows:
- the influence of acidity linked to the group hydroxyl;
- the influence of the length and the linearity of the carbon chain carrying the alcohol function and, - the solubility of these additives in the medium reactive.

Curves 11 to 17 have been plotted from points appearing in table 3 and they give, for the study of the different parameters the point effects of different types of alcohols.
For all the reagents studied, the effects of temperature having proved identical to those observed for additive A, it was not necessary to push the observations for this particular parameter. The effects conducted on the various alcohols were carried out at the constant temperature of 0C.

Curve 11 gives the representation of the variation of the degree of polymerization as a function of the variation of the Kappa index for an unbleached kraft dough characterized by a Kappa initia ~ l index of 40.2, a degree initial polymerization of 1950 and an initial whiteness 28.3. The witness appearing on curve 11 repeats these values. The different points of the curve materialize the results of the tests carried out with the different additives. These points are identified with the letter which corresponds to the additive tested, in accordance with the nomenclature given above.

It is clear from this curve 11 that a ozonation sequence marked "reference", allows to lower the Kappa index of around 10 points, with a result identical to reagent G (3,7-dimethyl-octan-3-ol). The reagent WO 95/03 ~ 21 B 7 ~ ~ 5 PCT ~ 4/00910 r G, very poorly soluble in aqueous media does not provide any improvement over an ozonation sequence classic without additive, from the point of view of the two parameters studied (degree of polymerization and Kappa index).
An ozonation sequence conducted in the presence of the reagent C (butan-2-ol) significantly improves the delignification with a corresponding fall in the degree of polymerization. The results can be considered as better than an ozone sequence excluding additives or a ozonation sequence carried out in the presence of reagent G. The fall in the Kappa index is approximately 20 points. It is specified that the reagent C is an alcohol secondary.
Going through curve 13 we find 4 reagents having substantially the same properties with respect to parameters studied. These reagents are B, D, E, F, in accordance with the nomenclature given above.
In this series of reagents, we see the presence of additive B which is a primary alcohol and linear while the additives D, E, F, are alcohols tertiary: alcohols D and E, being linear with, in this which concerns the additive E an additional carbon on the linear chain and as regards the additive F, a additional carbon constituting a ramification of the initial chain of additive D. These four reactants (B, D, E, F) have delignification properties substantially identical, slightly better than the additive vs.

Finally, additive A presents the best delignification characteristics, while retaining a exceptionally high degree of polymerization. Indeed, the fall in the Kappa index is around 26 points compared to the initial Kappa index, however the degree of polymerization retains a value of around 1400, this 2167 & ~ 5 ~ ~. r. r. ~ - r under drastic conditions since the sequence bl ~ nchim ~ nt and delignification was carried out in one single stage of ozonation, without prior pre-delignification oxygen.
It is therefore clear that the additive A, compared to the other types of alcohol mentioned above has the best delignification characteristics and conservation of the degree of polymerization.
Curve 12 represents the variation of the ratio DP / IK depending on the ozone treatment rate (TT 03).
As preC ~ emm ~ t ~ each point is identified by a letter corresponding to an additive mentioned in the no ~ en ~ lature given above. The "reference" notation specifies that it is an ozonation sequence in Absence of additive. As above, the witness is shown with the label "witness". The e ~ m ~ n of this curve 12 induces the following remarks. A sequence ozonation without the presence of reagent is significantly identical to an ozonation sequence in the presence of the reagent G. An ozonation sequence performed in the presence of reagent F is significantly better than the two sequences previously described. The three reagents B, D, and E, introduced into an ozonation sequence have substantially identical results between them. Reagent C has poorer perform ~ nc ~ s, however that the reagent A
found clear with perfor ~ n ~ - ~ greater than those other reagents, this under the operating conditions as previously specified.

It is recalled that the DP / IK ratio representative of the selectivity of ozone in the presence of reagent must be as high as possible to materialize the good selectivity. This is the case of the additive A which, for a rate 32 kg O3 / t ozone treatment unit value close to 100. This demonstrates, in a relevant way, good selectivity of ozone in the presence of additive A.

MO ~ lFlEE SHEET
IPEA / EP

W095 / 034 ~ 21 ~ 7 6 ~ ~ PCT ~ 4/00910 ~! , It is interesting to note that, given the rates of high ozone treatment, reagents A, B, C, D, E, F
all promote the transfer of ozone as described previously. We can therefore say that these reagents constitute excellent agents of the reaction medium favoring the transfer of ozone and its reactivity towards screw lignin.

Curve 13 representative of the degree of whiteness Bl according to the DP / IK ratio shows that the best delignification additives are also the best whiteness promoting additives. Additive A
also presents in this demonstration the best performance given that for a DP / IK ratio of 100 there allows, in a single ozonation stage, to reach a whiteness of 50, a gain of 22 points in the operating conditions used.

The curve 14 representative of the variation of the whiteness according to the TT 03 / ~ IK ratio appears relatively good performance for all additives, with a special mention for the additive A whose selectivity with respect to lignin is materialized by the lower TT 03 / ~ IK ratio. This additive A allows by elsewhere to get the best whiteness. The difference is very important compared to an ozonation stage alone without presence of additive for which the whiteness does not increase practically not and where delignification remains relatively small.
The curves 15 show the evolution of the whiteness according to the Kappa index. Two types of representation are shown on these curves 15.

The first representation groups the points conventionally obtained, drawn from the literature and having relates to a stage of ozone bleaching successive to a oxygen predelignification step, i.e.

WOg5 / 03 ~ PCT ~ 4/00910 2 ~ 5 32 the starting Kappa index of the ozonation sequence is located around 12 for an initial whiteness close to 36. This first curve makes appear ~ correlatively to the decrease in the Kappa index, an increase in the S whiteness up to the value of 75 under conditions industrial.

The second representation groups the points from the tests of the various additives, each of these points is identified by a letter ~ ui corresponds to the nomenclature given above for said additives. The curve thus obtained groups points with additive for temperatures of the reaction medium of 0C and 25C (the letters in italics are the values for 25C). As previously, references are given for sequences ozonation without additives. These are two neighboring points in the axis of the IK between 30 and 35.

This curve shows the decrease of the Kappa index regardless of the temperature value between 0C and 25C, under drastic conditions, since without prior delignification sequence a oxygen. We can see that the different points are substantially aligned on a curve whose general shape is given for information only.

As in the previous curves, the additive A is found free of other additives at 0C and allows appreciate the selectivity of delignification and increased whiteness.

The general trend of the curve shows that would have cut the classic curve from the literature around 9O to 92 white, only with a stadium ozone, compared to the classic curve obtained by setting work of an oxygen predelignification step followed of an ozonation stage.

2 ~ 6 7 ~ ~ 5 ~ ~ r ~ ir 3 3. ~. rr In a curve presented later, other points will be given according to the same representation in order to demonstrate the degrees of whiteness achieved and the Kappa indices compared to classic curves.

Curve 16 shows the evolution of the degree of whiteness according to the variation of the Kappa index for a temperature of O ~ C and for the various additives used. As before, the control points and reference are given for information only and they correspond to the starting point of the treated dough and as in the ozonation stage without additives. The ~ x ~ m ~ n of this curve shows that the reagent G although increasing the degree of whiteness does not allow a extensive delignification. Additives B, C, D, E, F are substantially grouped for the same values of the degree of bl ~ n ~ h ~ ur and Kappa IK index. Additive A is noticeably clear ~ from others with the best improved whiteness and better delignification.

Curve 17 shows the variation in the degree of bl ~ n ~ h ~ ur based on the estimated treatment rate in kgO3 / t of dry dough. As above, the witnesses and the reference are given for information only and they correspond respectively to the initial dough (control) and with ozonated dough without additives (reference).

Additive G is found as usual near of the reference. Additives B, C, D, E, F are substantially grouped together. Additive A is slightly released at the level of bl ~ nche ~ lr for the same rate of treatment. The treatment rate being appreciably identical for additives B, C, D, E, F and the degree of whiteness varying for this same treatment rate we can say that additive A plays the role of a very good transfer followed closely by additives B, D, E, better in absolute terms only the additives C and F slightly released.

FEUI ~ MODIFIED
IPEA / EP

2 1 ~ 7 ~ rrrrr 34, The additive G which appreciably increases the degree of whiteness for a low TT03 treatment rate, of the same order of magnitude that the reference, has a mechanism of action surprising. Indeed, although its power to aid the delignification is low, there is an increase not negligible whiteness for a treatment rate relatively low ozone. This is all the more surprising that reagent G is sparingly soluble in water.

The selectivity provided by the different additives so tested, which are all alcohols, is related to their own reactivity towards ozone. Today, in the available literature, a majority of researchers agree that the mode of activation of alcohols by ozone would be due to a 1,3-dipolar insertion, in accordance with the mechanism shown below:

--I ~ / - ii o H GOC ~ H
0 = 0 ~ _ The transition state has an ion character carbonium. This state is stabilized by the group hydroxyl which has a donor mesomeric character. It's here reason why the hydrogen located in C ~ of the function alcohol undergoes a nucleophilic attack on ozone. This mechanism corroborates the experimental fact that second alcohols react faster than alcohols primary. Indeed, in secondary alcohols, the proton in o ~ of the alcohol function is more acidic than in primary alcohols. This is the case for reagent C.

FEUlLLE MO ~ IFIEE
IPEAIEP

W095 / 034 ~ 7 ~ ~ ~ PCT ~ 4 / OO91o Primary alcohols mainly give the corresponding acids, the aldehydes being in this case minority products. This is the case for additive B.

The ozonation of secondary alcohols gives the ketones and corresponding acids. This is the case of the additive vs.

The formation of these products follows from the patterns reactive, known in the current state of the art and which are given below for information.

WO 95/03448 `1 PCT ~ R94 / 00910 2 ~ 676 ~

RHRH
\ C '/ ~ ~
RCH20H + 3 ~ H ~ 3 ~ HOHO

RCHO + HOH + 2 RCOOH + HOOH

R ~ CHz RCH3CHOH + 03 ~ ~ H ~ O ------ ~ H203 + HO-CR = CH2 HO

"HC ~ O etc RC Oo + OOH ~ RCOOH + CH300H

OH

ACTION SHEET (RULE 26) W095 / 03448 216 7 ~ ~ 5 PCT ~ R94 / 00910 These diagrams show an intermediary hydrotrioxide which breaks down in several ways depending on the type of alcohol to give the products detected.

The ozonation of tertiary alcohols is very slow.
It likely occurs with an attack of hydrogen from the alcohol function to produce a radical alkoxy. This is the case for additives A, B, E, F which appear to be the most relevant through tests conducted by the applicant in the conditions previously exposed. This is in contradiction with Meredith's claims (US-A 4229252) according to which the additives of ~ ype primary alcohol would be more efficient in the context of ozonation sequences than additives of the secondary or tertiary alcohol type.

In all the tests conducted by the applicant no marked difference was found according to the length and branching of the carbon chains tertiary alcohols, to the extent that these alcohols are known to be soluble in the aqueous medium.

Once the properties of additive A, it was necessary to practice tests aimed at demonstrating the influence of the amount of additive in the reaction medium. The results thus obtained are recorded in table 4 below, o ~ the different classical parameters were studied according to the percentage of additive introduced into the reaction medium.

21 ~ 7 ~

CC ~
m ~

t ~ I _ _ _ _. . or ~, N

1 ~ t` ~ CD 0 ~ D ~ O 1 ~ N ~ t ~ ~ ~ 0 Y u ~ ~ o ~ a- o tD

oo ~ n ~ o tD ~ - O a ~
~ 1 _______________ Y

0 ~ D ~ ~ D
~ ~ ~ O 0 0 0 ~ 7 ~ CD ~ D ~ C ~ _ ~ --00 - o ~ cn1 ~~
E
~ D

., ~ xxxxxxxxxxxxxx 1-- 0 0 0 0 0 0 0 0 0 ~ IN t ~

20 ~
-o o ~
'.--_ ~ ~ oo ~ o ~ o ~ oo ~ oo ~ o ~ oo ID

Z o ~ ~ ~

.

CCC `ID CCC` 0 ~) CD ~
EEEEEEEEEEEEEEE

SUBSTITUTE SHEET (RULE 26) rr 2 ~ ~ 6 7 ~ 0 5 r; rr ~ ~ ttr Curve 18, taken from the elements contained in this table 4 represents the variation of the treatment rate in ; ozone as a function of the percentage of additive introduced into the reaction medium for the two reference temperatures usually used: 0 ~ C and 25C. Curved gods thus obtained have substantially the same appearance, with nevertheless better performance for the curve obtained at 0C. These curves show that the amount of additive to introduce into the reaction medium to obtain the previously described effects is weak and is not necessary to introduce significant quantities of this additi ~ to obtain concrete results. A percentage of additive A of between 1.7 and 7% by mass allows achieve significant results.

Curve 19 represents the variation of the index Kappa as a function of the percentage of additive A introduced into the reaction medium ~ for the two temperatures of reference 0C and 25C. We see that the curve at 0C
allows better delignification (reduction of the Kappa index) open the curve at 250c, this for identical mass percentages of additive A introduced in the reaction medium. It appears that the best delignification takes place when a percentage is used additive between 1.7 and 7% by mass.

The curve ZO represents the variation of TT 03 / I ~ o-IK in ~ anointing of the paurcentage of additive A introduced into the reaction medium for reference temperatures O ~ and 25C. The curve drawn for the temperature of 0C makes appear much better results than the plotted curve for the temperature of 25C. The TT 03 / IKo-IK ratio is minimum for a percentage of additive A of between 1.7 and 7% by mass. These results compared to those available in existing literature shows very poor poverty significant since ~ the best results according to this ~
literature give a TT 03 / IXo-IK ratio greater than 1.2 SHEET ME: ~ IFIEE
IPEA ~ EP

WOg5 / 034 ~ PCT ~ 94/00910 2167 ~ 5 ,,,; `40 and this during an ozonation sequence following a predelignification with oxygen then we obtain, on a direct sequence to ozone without predelignification a value of the TT 03 / IKo-IK ratio of 1.13 on average, value lower than that given in the literature.

Curve 21 represents the variation of the ratio DP / IK as a function of the ozone treatment rate for reference temperatures OoC and 25C, in the presence of additive A. The curve plotted from the relative points ~
the temperature of 0C is better than the curve obtained a from the points for the temperature of 25C. We have explained previously the importance of the DP / IK ratio in specifying that it had to be as high as possible in order to properly materialize a good delignification, without significant drop in the DP index. The introduction of the additive At 0C, DP / IK ratios close to 100 appear, which demonstrates the selectivity of this additive A during ozonation sequences. This DP / IK ratio of around 100 is obtained for quantities of additive, expressed in mass percentage, between 1.7 and 7% by weight of dry matter. The materialization of this statement is given by curve 22.

The properties of additive A having been evidenced by the curves and tables previously clarified, the plaintiff verified that it was possible to push delignification using a sequence of sequences using ozone in the presence of the additive A and by introducing intermediate washing stages, style sequences: Z wash Z wash. Table 5 below after summarizes a number of values obtained experimentally from an unbleached chemical paste, the starting Kappa index was 31.5 and the degree of polymerization of 1650.

WO 95/03448,. . . `-` PCT / FR94 / 00910 2167 ~ 05 o 0 m ~ ~
Yr ~
o - ~ ~ a t ~ - - -~~ ~ 0 ~
o ~ 0 o 0 U ~ ~ I` ~
~ D ~ - O
U ~ Lq - ~ D ~ U) Y ~ ~

o ~ ~ CO
- ~ r, u ') ~ O

, ~
,. ~ xxx Y ~
oooooo ~
'D

o ~ ~.
g `2 ~~
ae Zo - ~ ~

E ~ ~ 'EE

REPLACEMENT SHEET (RULE 26 ~

21676D5 ~. .
r ~ ~ t Under the operating conditions such as illustrated by this table 5, that is to say with a dough suspension with a consistency of 3 ~ for an ozone load of 20 kg / t of dough and for a addition of additive A up to 6.7% in temperature of the reaction medium of 0C, after a acid pretreatment, the above results have been obtained after.

L0 The effective ozonation rate of the dough has raised to 15.4 kg / t of dough for a Kappa index after ozonation of 16.5 and a degree of polymerization of 1328. The characteristic report TT 03 / ~ IK stands at 1.027 however the DP / IK ratio is 80.48 for one degree whiteness equal to 48.

If we practice delignification and white ~. ~ im ~ nt in two stages of ozonation separated by a washing, and under the same operating conditions as previously, we obtain an ozone treatment rate of 26.8 kg / t of dough, for a final Kappa index of 5.9 and a degree of polymerization of 1174. The treatment rate on ~ IK is equal to 1.047 however that the DP / IK ratio is of 198.98 for a degree of whiteness equal to 64.9.
The third experimental stage has been conducted, always without oxygen pre-lignification, using three stages of ozonation separated by washes of the p ~ te. Under always identical operating conditions the following results were obtained:
- ozone load 60 kg / t of dough - ozone treatment rate 30 kg / t of dough - IK

- TT 03 / ~ IK 1,099 - DP / IK ~ 312 - Final whiteness 67.3 ~ EUlLLE ~ / IO ~ IFIEE
IPEA / EP

21 G7 ~ Q ~

43 -. . . .
These results dismantle ~ it is possible to delignify and launder to values accepted without assume a final bleaching stage, a dough type unbleached chemical without prior delignification stage oxygen with exceptional characteristic differences for this type of treatment. Indeed, the TT 03 / ~ report is always less than 1.1, however DP remains greater than 1000 and the whiteness reaches values appreciable.
Of course these results would be magnified and reduced ozone quantities if the same were done operations, after a predelignification stage at oxygen. This highlights the results obtained by the plaintiff and the beneficial effects of additi ~ A.

During sequences as described above it is possible to reuse additive A by recycling it from one stage to another ~ This is made possible by the fact that this additive A is not consumed and that it retains its properties after several successive stages of ozonation.

The previously described tests were carried out from an unbleached chemical pulp of the sulfate type.
Z ~
A ~ in to highlight the results obtained on this type of dough, the applicant has practiced a certain number of trials on a sulfite type dough. The results from these investigations are gathered in the table 6 below:

~ EUlLLE lJloD / lFlEE
~ / EP

WO 95/03448 PCT / FR94 / OOglO
~ 1 ~ 7 ~

N In a ~
- OO ~ N ~ J
m ~ ~ D ~ CD r ~
~ ly WE
t ~ _ooc ~ ~
y ~ ~ S ~ cr ~
~ o ~
ON ~ N ~ ~
U) L ~ ~ I ~ N
a ~ mm ~ - -_ _ _ _ _ N _ I ~ U) O ~ ~ n f_ V _ ~ _ P ~ ~ U7 I_ N ~ JOO

ae ~, ~ D

~ ~, e ~

.c ~ oooo ~ Y _ _ _ _ a ~

. .
n ~ IY
Z ~ D ~ tD ~ .D

`C ~ ~
~ EE

SUBSTITUTE SHEET (RULE 26) 2 1 6 7 6 0 5 ri I rrrr 4 5. q The treated unbleached sulfite paste had a hint Kappa of g, 2, a degree of polymerization from 1935 and a initial whiteness of 60. This off-white sulfite type paste had undergone prior to the ozonation stage a stage of delignification with pure oxygen in the presence of reagents classified for this operation. The trials `which have been conduits included conventional ozonation stages, without additive A, and ozonation sequences modified with introduction of the additive A into the reaction medium. The percentage of additive A, when used was 6 t 7% by mass of dry matter. Ozonation tests with or without additive A have been driven for both reference temperatures 0C and 25C.
An ozonation sequence conducted at a temperature of 25C, in the presence of the additive A
appear for a TT 03 of 1.1 kgO3 / t of dough, at the index Kappa of 8.1 and a degree of polymerization from 1895. The TT 03 / ~ IK ratio is 1, DP / IK ratio is 233.95 and the degree of whiteness at 60.2.
We therefore see that an ozonation sequence classic, driving in the absence of the additi ~ A leads to weak delignification, a relatively modest decline in degree of polymerization and substantially whiteness identical to the initial whiteness. Treatment with ozone under these operating conditions is substantially Without effect.
For the same temperature of 25C, a sequence modified ozonation in the presence of additive A
appear for the same initial ozone load a TT 03 2.3 kgO3 / t of dough, a Kappa number of 6.7, a degree of polymerization of 1859, a characteristic report TT03 / ~ IK of 0.92, a DP / IK ratio of 277.46 and a degree whiteness of 63.5.
Several remarks are in order. The first one relates to increasing the ozone treatment rate for ~ EUILLE MOD ~ FIEE
IPEA / ~ P

2167GO ~; ~; rrr ~ -. .
_ 46 the same theoretical charge of introduced ozone, which is explained by me ~ An; smes of transfer and of accessibility previously described. The degree of polymerization after ozonation is substantially identical to that obtained in the absence of the additive A, ~ the ratio TTO3 / ~ IK is significantly lower and less than one, the DP / IK ratio is increasing significantly and the degree whiteness increases by 3.5 points.

A classic ozonation sequence conducted outside presence of additive A and for a temperature of OC made show the following results:
- The TTO3 is 1.35 kg of O3 / t of dough, in slight increase compared to the figure obtained at 25C;
- The Kappa index stands at 7.5, down on that obtained under conditions identical to 25C;
- The degree of polymerization was established in 1897, value substantially identical to that obtained at 25C;
- The characteristic ratio TTO3 / ~ IK is equal to O, 79;
- The DP / IK ratio is equal to 252.93 and it is in increase and - the degree of whiteness is 62.8, slightly increase from the same point at 25C.
A modified ozonation sequence conducted at OC
in the presence of additive A gives the following results:
- TTO3 is 4.3 kgO3 / t of dough;
- The Kappa index, after the ozonation stage stands at 4;
- The degree of polymerization is established at 1742;
- The characteristic ratio TTO3 / ~ K is equal to O, 83;
- The DP / IK ratio is equal to 435/5 and - The degree of whiteness is established at 72.2.
These values allow in the case of a dough ecru chemical sulfite type to consolidate the demonstration MODJFIED SHEET
IPEA / EP

W095 / 034 ~ 216 7 ~ ~ S PCT ~ 4/00910 made from the results obtained on a chemical paste ecru sulfate type. The degrees of whiteness obtained are higher in absolute value than those obtained on a dough ecru chemical sulfate type. This confirms the facilities of whitening that this type of dough presents.

The beneficial influence provided by the additive A, during an ozonation sequence and whatever the temperature, is highlighted by the results obtained in the same way as the beneficial effect of temperature during the ozonation sequences.

It is interesting to note that the degree of polymerization obtained (1742 for a Kappa index of 4 and a whiteness of 72.2) is exceptional, which demonstrates the selectivity provided by the additive A, as well as the protection of cellulosic constituents or hemicellulosic dough and more generally carbohydrates.
We took the values from curve 15 and we supplemented by the results from Table 6. All of these elements are grouped on curve 23 which allows materialize all the results obtained.
This curve 23 demonstrates the validity of the results obtained and the excellent performances compared to those known methods. It also demonstrates that it is possible to delignify and whiten simultaneously a dough with a starting Kappa index greater than 30, using a single sequence (in one stage or in two stages), without any problem of appreciable decrease in the degree of polymerization with increased whiteness significant.
This curve also shows that when using additive A, for the same Kappa index, we achieves a significantly higher degree of whiteness than W095 / 03 ~ ~ PCTn ~ 4/00910 21676 ~

that we would obtain under operating conditions classics as described in the prior art.

The previous literature describes, during bleaching sequences the use of chemical additive type oxalic acid, acetic acid, etc ..., so it was interesting to check if this type of chemical compounds used simultaneously with additive A was likely to bring interesting properties during the stages of ozone bleaching. To this end, the plaintiff has performed a number of tests by combining additive A
with oxalic acid or acetic acid. The tests were conducted on a chemical pulp of the sulfate type having a Kappa index of 31.5, a degree of polymerization of 1650 and a degree of whiteness on the order of 30. Several sequences have been studied to allow different comparisons.

The first test consisted of a stadium ozonation in the presence of the additive A introduced according to a mass percentage of 6.7 with respect to the mass of dry matter. The TTO3 was 15.2 kgO3 / t of dry pulp, the Kappa index after ozonization of 16.5, the degree of polymerization of 1328, however that the DP / IK ratio stood at 80.48 and the TTO3 / ~ IK ratio at 1.013.
The second sequence performed consisted of add a mixture of additive A and oxalic acid in the reaction medium. Mass percentages respective of the two additives were:
- Additive A: 3.3 ~
.- Oxalic acid (additive H): 1%
The results obtained were as follows:
- TTO3: 16.2 kgO3 / t of dough;
- Kappa index: 17.2;
- Degree of polymerization: 1420;
- DP / IK: 82.56;
- TTO3 / ~ IK: 1.13 wo gs / ~ 4 ~ 216 7 ~ ~ 5 PCT ~ 4/00910 The third test carried out concerned the introduction of a mixture of additives comprising the additive A for a mass percentage of 3.3 and acetic acid (additive I) for an amsic percentage of 4.4. The The following results were obtained:
- TT03: 14.8 03 / t of dough;
- Kappa index: 16.4;
- Degree of polymerization: 1363;
- DP / IK: 83.91;
- TT03 / ~ IK: 0.980;

The fourth test carried out involved a mixture of additive A for a mass percentage of 3.3 with acetic acid in a percentage of 52.8. The results were as follows:
- TT03: 14.66 03 / t of dough;
- Kappa index: 15.4;
- Degree of polymerization: 1324;
- DP / IK: 85.97;
- TT03 / ~ IK: 0.981;
All of these results are summarized in the table 7 below:

WO 95/03448 ~ ~ I'CT / FR94 / 00910 ~ 1 ~ 7 ~

o - ~ a- ~
t ~ __ oo y 0 0 ~ _ ._ SQ ~ iot ~

u) I
Y ~ _ _ ~
~ Q ~ D
OV
t ~ __ ~ ~

'~ XXXX
oooo v C 6 I ~ ~

~ ~ OOOO

o ~ o -j, ~,;

E ~ E ~ E ~ - ~ ~
U ~ ~ <- 1 ~

REPLACEMENT FEIJILLE (RULE 26) W095 / 034 ~ 216 ~ 6 QS PCT ~ 4/00910 Reading this table allows you to go account of the good results obtained by the additive A used alone. The combinations of this additive A (2-methyl-propan-2-ol) plus oxalic acid or this additive A plus acid acetic all show relatively good results identical whatever the criterion examined.

It is however interesting to note that it is necessary to introduce significant amounts of acetic acid.
in combination with additive A to obtain results suitable in terms of delignification or selectivity.

In all cases it can be noted that the values of TT03 are excellent since they are close to or less than 1.1.
Although the results obtained by mixing additive A with oxalic acid or acetic acid can be considered good it should be noted that to get similar results ~ the additive A used only it is necessary to introduce a mixture of oxalic acid or acetic acid, in very high mass percentages.
This means that the protective or selection effect of additive A, considered alone and in small percentage mass is much greater than the respective effects of acids oxalic and acetic used alone or in mixture with additive A.

Table 8 below gives a summary of the evolution of the characteristics (IK, Bl, DP) of a dough unbleached kraft after treatment, at room temperature, by ozone (flow rate of 0.3 Nm3 / h and a concentration of 100 g / Nm3), in the presence of a tertiary alcohol, in particular t-BuOH.

Initially this dough has an IK of 23, a DP
from 1610, a Bl from 35. It also has a consistency 35%, a load of 1.5% (by mass compared to the dough dry) and it underwent an acid pretreatment pH = 2.5.

52 _ ~
2167605 Table 8 Amount of t-BuOH IK Bl DP
(% by mass) 0 9.6 56.4 1210 9 59.3 1220 8.5 60.2 1240 8 61.3 1250 7.4 62.2 1240 21676 ~ 5 rrrr; rrrr 53 ,, ~,. ..

A study of this table suggests that the consistency (35 ~) of mixture has a favorable influence on the whole of the results; the choice as addit7f of t-BuCK
verifies his role as agent of transLert, he per ~ and lower Xappa tIK) while increasing the degree of white ~ eur (B1) for a de ~ re polymerization (DP) pratiaue ~ ent constant.

lC As he apoaralt at court ~ e 24, the influence of the additive, in this case t-BuOH, is préDcndér ~ nte on the selectivity of ozone.

The court ~ 25 illustrates the evolution of the index KaF7J2 in ~ anointing of the percentage of tertiary alcohol (t- ~ uC ~;) used.

SHEET MOD ~ FIEE
IPEA / EP

Claims (10)

1. Unbleached paper pulp bleaching process of the chemical type using ozone characterized in that it only uses an ozone stage exclusively, in presence of a tertiary alcohol, comprising from four to eight carbon atoms that is introduced into the medium reaction maintained at a temperature between -5°C
and 80°C, prior to the ozonation stage proper said, in order to improve the gas-liquid transfer, the exchange potential, the selectivity of the oxidation of the lignin and ozone efficiency, the consistency of the pulp subjected to ozonization being between 6 and 60%. 2. Bleaching process according to claim 1 characterized in that said tertiary alcohol comprises four to six carbon atoms. 3. Bleaching process according to claim 1 characterized in that said tertiary alcohol comprises four carbon atoms. 4. Bleaching process according to any of the preceding claims characterized in that, after reaction, the alcohol is recycled and reused without treatment particular in the process. 5. Bleaching process according to any of the preceding claims characterized in that the ozone is introduced in successive stages into the medium reaction. 6. Bleaching process according to any of the preceding claims, characterized in that said alcohol is associated with another oxygenated product. 7. Bleaching process according to any of the preceding claims, characterized in that said alcohol is introduced according to a mass percentage, by relative to the dry pulp, between 0.01 and 300%, of preferably between 0.1 and 100% and better still between 1 and 10%. 8. Bleaching process according to any of the preceding claims, characterized in that the temperature of the reaction medium during ozonation is between 0°C and 60°C and better still between 0°C and 25°C. 9. Bleaching process according to any of the preceding claims, characterized in that the ozone stage is implemented after a preliminary stage of oxygen delignification. 10. Bleaching process according to any of the preceding claims, characterized in that the ozone stage is implemented after a pretreatment of pulp, between oxygen pre-delignification and ozonation stage proper.