FR2785303A1 - Papermaking process uses an additive of at least one humic material or its derivative at the wet stage to increase mechanical properties and raise the machine production speeds - Google Patents

Abstract

To improve the quality of paper during its production a volume of at least one humic material or its derivative is added to the paper at the wet stage of the papermaking machine or to the pulp. The additive is fed into the wet pulp at a rate of 0.005 - 6.00 (2-1.0)% of dry additive in relation to the dry paper material. The additive is fed into the wet pulp at the wet section of the papermaking machine before the web has dried by 45% (particularly 5%). The humic material is derived from composting and particularly of peat or reoxidized coal. The additive can also be potassium humate.

Description

IMPROVED PAPERMAKING PROCESS
The invention relates to an improved process for manufacturing paper.

 For the purposes of the present invention, the term "paper" means any type of product obtained by the use of a paper technique but which, in reality, can be related to both paper and cardboard as non-woven products, felts, sails, etc. This term "paper" therefore denotes in the following any sheet not only based on cellulosic fibers, the raw material most frequently used in the paper and cardboard industry, but also based on synthetic fibers such as polyamides, polyesters and polyacrylic resins, and mineral fibers such as asbestos, ceramic and glass fibers.

 The production of paper, whatever the type of machine used, is always based on the same principle: a mixture of fibers and water is conducted on a canvas (Fourdrinier canvas) so that the water flows through the canvas and a damp veil is retained. This veil is then subjected to treatments under vacuum and under pressure (in presses), so as to remove more water, then it is finally dried by passage over drying cylinders heated with steam.

 Conventional papermaking processes first include a step of preparing the pulp.

The fibers are thus mixed with water in a pulper to form a thick pulp. Then the additives, in particular the fillers, both mineral and organic, and the retention agents, such as starches, are added in well defined proportions in the pulper. The suspension thus made up of fibers, additives and water is then treated in order to obtain the required quality: the suspension is refined, stored in mixing tanks, passed through cyclones and sieves to remove the impurities bigger. At the end of this preparation stage, the suspension contains approximately 99% water and 1% pulp and additives, which constitutes the refined paste.

 The next step, that is to say the step of forming the sheet, consists in removing the water from the suspension thus prepared, so as to form a uniform sheet of paper with well defined characteristics (grammage, opacity, porosity, mechanical resistance, whiteness, printability, etc.). The removal of water on a Fourdrinier type machine is carried out on three successive sections: a forming section, a press section and a drying section.

 In the forming section, water is removed by dripping through a fabric. On the head box, the refined dough is brought and dosed through the slot in the head box on an endless canvas where the majority of the water drips, both naturally and using suction. When the consistency reaches about 5%, the water stops dripping and must be removed in the following press section. The wet sheet or veil thus passes through several presses of two rolls each. The water is removed both by pressure between the two rollers and also by suction. Most generally, at the exit from the press section, the consistency of the sheet reaches approximately 40%. The sheet then passes over the surface of a series of steam heated dryer cylinders. The water is removed by evaporation, and at the exit of this drying section, the consistency of the sheet is about 90-95%.

 Depending on the characteristics of the paper required, the paper sheet is then simply wound or calendered, or surfaced, using a "size-press" which is generally located in the drying section, or coated.

 Historically, papermakers have tried to improve the speed of draining as well as the retention of fillers and "fines" at what is commonly referred to as the wet section of the paper machine. that is, the part which is located upstream of the drying section.

 Thus, one or more organic retention agents such as starch, generally cationic, carboxymethylcellulose, alginates, polyacrylamides, polyethylenimine, polyamides ..., or mineral retention agents such as sulfate aluminum, sodium aluminate, aluminum polychloride or aluminum polychlorosulfate ..., are added to the paste, which contains in particular mineral fillers such as kaolin, calcium or magnesium carbonates, talc, titanium oxide, alumina hydrate, sodium silico aluminate, calcium sulfate, etc ... These retention agents, more or less effective, have the effect of improving the speed d drainage, by advancing the water line towards the head box, improving the retention of fillers and fibers, and reducing the quantity of suspended matter (MES) in the paper machine's drainage water , also called "white waters".

 Unfortunately, despite the addition of these retention agents and the addition of aluminum ions, the bonding and charge retention properties in the paper sheet are still insufficient and the content of suspended solids in white water remains too high. . There is therefore still a huge demand from the paper industry for an improved paper manufacturing process allowing better retention of fibers and fillers, to decrease the rate of suspended matter in the drainage water. , and to increase the mechanical characteristics of the paper obtained.

 However, it is to the credit of the inventors to have found that the addition in the wet section of the paper machine of an effective quantity of a humic product or of a humic derivative made it possible to satisfy these various desiderata of the papermaking technique, by significantly increasing the retention of fillers and fibers, by significantly reducing the MES rate in water under canvas, and by significantly increasing the mechanical resistance characteristics of the paper.

 The improved process for manufacturing paper according to the invention is therefore characterized by the fact that an effective amount of at least one humic product is added to one or more places located in the wet section of the paper machine or at least one humic derivative.

 In the context of the present invention, the term humic product and humic derivative denotes humic substances or humified organic materials and their derivatives, and more particularly the products selected from the group comprising humic acids, fulvic acids, humates, fulvates, hymatomelanic acids, uronic acids, polyuronides and humine, their derivatives, and mixtures thereof.

 These products are present in particular in leonardite or peat.

 Humic products represent a large part of the organic matter present on the surface of the planet and result from the biological and chemical degradation of plant and animal residues, as well as the activity of synthesis of microorganisms.

 The degradation of organic matter can be divided into two parts: humification and the formation of hard coal. In the humification process, we find the formation of recent humic matter, such as that present in peat, while in the genesis of coal, we highlight the formation of fossil matter.

 Regarding humification, when plant and animal residues enter the soil, an aerobic biochemical oxidation process takes place. During this stage of dynamic transformation of molecules, we observe the synthesis of the basic elements composing humic products. This metabolism results from the catabolism of aromatic groups (lignins, tannins, flavanoids, glycosides, etc.) accompanied by the release of NH3, H2S, C02 and CH4.

 The aliphatic molecules of organic matter take on an aromatic conformation. Hydrocarbon materials and proteins decompose rapidly in the first stages of humification and their derivatives bind, via extremely fragile physical or chemical bonds, to humic materials, thus forming their ramifications.

 Resins and natural waxes cannot be degraded and are accumulated in the human body.

 In a later stage of this biological oxidation process, the aromatic molecules are transformed into molecules with an oxyquinone structure. The latter then enter into a polymerization process, oxygen bridges being established between the aromatic molecules.

 The first stage of humification therefore consists in the decomposition of large organic molecules into smaller aromatic compounds, and the second stage consists in polymerizing these aromatic derivatives into humic matter.

 Coal formation, on the other hand, is a natural process by which the carbon content of humified matter increases. During this process, the degree of polymerization of the molecules increases while the microbial activity decreases. The increase in temperature and pressure help in the formation of these polymers.

 The first stage of coal formation begins when the humic matter is flooded, which induces an environment under anaerobic conditions. The microbial activity decreases and the initial oxidizing environment changes to a reducing environment, which promotes the polymerization reaction. This transformation is periodic, since wetlands can evolve into dry areas. These aerobic, oxidative, and anerobic, reducing periods alternate and when the deposits are covered with inorganic mineral deposits, the second abiotic phase begins. Under these anaerobic conditions, life stops and the polymerized molecules continue their process of dehydration, decarboxylation, and dehydrogenation.

 Under these reducing conditions, molecular condensation continues and the bonds (aromatic-C-O-C- aromatic) evolve to a condensate (aromatic-C-Caromatic) then to anthracene bridges (aromaticaromatic).

 Coal formation is reversible in the presence of water and air. This can be observed during the rise of coal rocks to the surface of the earth or during the infiltration of water and air into the rock. This type of hard coal is called reoxidized hard coal. It is in this reoxidized coal that we generally find the best qualities of humic acids. Unfortunately, however, the mines containing this reoxidized coal are few in the world.

 The humic products used in the process according to the invention can therefore in particular be derived from materials resulting from humification (peat in particular) or from reoxidized coal.

 These products have complex structures, which depend on their formation process (humification or coal formation) as well as on the moment of their evolution in this formation process.

Site ACTIF R= {-CH2-;-CHOH-;-CH=CH-; cycle ?
Plus l'humification est poussée vers la formation de la houille, plus la structure des produits humiques ressemble à la structure (B) présentée.The following two diagrams show the conformation of molecules representative of humic products which can be used in the process according to the invention:

ACTIVE site R = {-CH2 -; - CHOH -; - CH = CH-; cycle?
The more the humification is pushed towards the formation of the coal, the more the structure of humic products resembles the structure (B) presented.

 The number n of aromatic monomers constituting these products constitutes a variable which makes it possible to define either the presence of humic acid or the presence of fulvic acid: if n is less than or equal to 10, it is fulvic acid, whereas if n is greater than 10, it is humic acid.

 In general, in the context of the present patent application, the term "humic products" means humic substances or humified organic matter; by the term "humic acids" the fraction of humus extracted in an alkaline medium, which contains different polyhydroxycarbonic acids of variable molecular weight, containing humic acid and fulvic acid; by the term "humic acid" the fraction extractable in alkaline medium from humus substances, insoluble in acidic and alcoholic medium; by the term "fulvic acid" the extractable fraction in an alkaline medium of humus substances, soluble in acidic and alcoholic medium; by the term "humine" the fraction of humus substances insoluble in alkaline medium; by the terms "humates" and "fulvates" the different salts of humic acid and fulvic acid: humato-or fulvato-metallic complexes, humato-or fulvatoalkali, humato-or fulvato-cationic charge ...

 For the purposes of the present invention, the term "humic derivatives" means the products obtained from humic products previously defined by reactions which do not essentially modify their molecular structure or skeleton.

Among these reactions, mention may in particular be made of esterification, etherification, oxidation, controlled hydrogenation and crosslinking reactions.

 Preferably, an amount of humic products or humic derivatives of between 0.005% and 6% is used in the process according to the invention, preferably between 0.01% and 5%, and even more preferably between 0.02% and 1 %, these percentages being expressed in dry weight of humic matter relative to the dry weight of paper.

 As indicated previously, the humic product or the humic derivative can be added at one or more points located in the wet section of the paper machine, that is to say in practice before the sheet of paper reaches a rate about 45% dryness. Preferably, most of the addition is carried out before the sheet of paper reaches a dryness rate of 20% and more preferably still 5%.

 The humic products or humic derivatives used in the process according to the invention can be added alone or in admixture with the other retention agents or the additives and fillers which must be included in the composition of the paper.

 The method according to the invention provides a very significant improvement in the bonding properties, retention of charges, fine elements and other additives, which results in a significant reduction in the suspended matter in white water.

The use in the manufacture of paper of humic products or humic derivatives in accordance with the present invention also improves:
-draining of the sheet on the canvas of the paper machine as well as the physical characteristics of the paper obtained. The speed of the machine and its productivity are therefore increased.

 -the efficiency of use of consumable products on the machine.

 -the purification yield on canvas water, expressed by a drop in the content of suspended matter and the chemical oxygen demand. This induces a very clear relief of the polluting load at the level of biological and physico-chemical treatment plants.

 The invention also relates to the use of humic products and humic derivatives for the production of paper.

 It can be better understood with the aid of the examples which follow, which are given purely by way of non-limiting illustration.

EXAMPLE 1: Manufacture of cardboard for tubes.

 Cardboard for tubes is manufactured according to the conventional method and according to the method according to the invention, that is to say with the addition of humic products.

The characteristics of the cardboard are as follows: -weight: 400 g / m2 -fibrous composition 100% of old paper and
boxes - retention agent: cationic polyacrylamide
0.4% compared to fibers
and poly aluminum chloride to
18% in A1203, at the rate of
1, 2% compared to fibers - mass additives: starch at 6% compared to
fibers.

In the conventional process for manufacturing this cardboard, the following data are noted: -on canvas waters:
Turbidity FTU: 430
TH (F): 80
Aluminum content: 1.6 ppm
The machine speed is 49.5 m / min
The internal cohesion of the cardboard thus produced is 210 J / m2.

 During the preparation of this cardboard according to the process according to the invention, 400 grams per tonne of cardboard of potassium humate are added, in the form of a concentrated solution at 18% relative to the dry matter.

A few hours after the introduction of this product, at a potassium humate level of 0.04% compared to the fibers, we can see that the above parameters have evolved as follows: -on canvas waters:
FTU turbidity: 360 (i.e. -16%)
TH (F): 60 (i.e. 25%)
Aluminum content: 0.5 ppm (i.e.-68%)
The machine speed could have been increased by approximately%, to reach a value of 51.5 m / min.

 Furthermore, the internal cohesion of the cardboard obtained according to the process according to the invention has been notably increased, to a value of 240 J / m2, ie a difference of + 14.3%.

EXAMPLE 2: Manufacture of printing and writing paper.

The characteristics of said paper are as follows: -weight: 80 g / m2 -fibrous composition: 20% deinked pulp,
40% chemical pulp
bleached softwood
30% chemical pulp
bleached leaves
10% broken manufacturing - load: 18% calcium carbonate
compared to fibers - glue: Rosin reinforced at 3% by
compared to fibers - retention agents: cationic polyacrylamide to
0.4% compared to fibers
and poly aluminum chloride to
18% in A1203 at 1% compared
to fibers - mass additives: carboxymethylcellulose
sodium at 0.3% compared to
fibers.

The production of this paper according to the conventional process gives the following values:
Turbidity of water under canvas FTU: 36
bonding pH: 7.3
Burst index: 2.23
COBB bonding index 1 ': 15 g / m2
When the paper is prepared using the process according to the present invention, with the addition of potassium humate concentrated to 18% relative to the dry matter, with a dosage of 500 g per tonne of paper (i.e. 0.05% compared to the fibers), the following characteristics are obtained:
Turbidity of water under FTU fabric: 24 (i.e. 33%)
bonding pH: 7.3
Burst index: 2.46 (i.e. + 10%)
COBB bonding index 1 ': 13 g / m2 (-13%)
EXAMPLE # 3
The tests were also carried out in the laboratory, on 200 g formulas.

The fiber composition was made of 100% waste paper and the adjuvants were as follows:
-6% native wheat starch
-0.5% Guar fines
-1.2% 18% poly aluminum chloride
-0.4% cationic polyacrylamide
A humic product of the potassium humate type was added, at a rate of 1% and 2% relative to the fibers.

The addition of this humic product makes it possible to very clearly show the formation of an aggregate of the materials present in the dough. The flock is not scattered.

 The contact time for potassium humate is 2 minutes in the dough.

The following results were obtained:
Control 1% Humate K + 2% Humate K +
Burst 0.9 1.2 1.75
Internal cohesion 44.5 63.3 74.9
Earnings / + 30 to 40% + 60 to 95%
EXAMPLE n: preparation of cardboard for 440 g / m2 tubes
The fibrous materials used consisted of 100% old paper and cardboard.

The retention officers were:
cationic polyacrylamide at the rate of 0.4% relative to the fibers, introduced at the machine head, and
-polychloride of aluminum at 18% in A1203, at the rate of 0.8% compared to the fibers, introduced into the vat room at the head of the machine.

Mass additives:
- native wheat starch at a rate of 5.35% compared to the fibers, introduced in thick paste, and
- anionic galactomannan at the rate of 0.59% compared to the fibers, introduced in thick paste.

The machine parameters were as follows:
-production: 2446 kg per hour
-speed: 49 m / min
The physical characteristics of the cardboard obtained according to the conventional manufacturing process were as follows
- internal cohesion: 216 J / m2
- burst index: 8.9
- Ring Crush, cross direction: 88.5 daN
- breaking length, direction
walk: 27 N.

 The humic product was added between the pulper and the thick pulp vat, at a rate of 0.05% relative to the fibers.

 As soon as it arrives on the cardboard machine, approximately 4 hours after its introduction, which corresponds to the normal time to pass from the pulper to the head box, it was first observed that the water line receded, which reveals an acceleration of the drainage, and a significant drop in the steam in pre-drying, hence an acceleration of the speed of the machine, which could reach 51.5 m / min.

 In a second step, the primary physical characteristic of cardboard, that is to say internal cohesion, was analyzed: it increased by 23%.

This improvement has enabled a gradual decrease in the amounts of starch and galactomannan adjuvants, in the following proportions:
-starch rate: -8. 5%, i.e. a rate of 4.93%
compared to fibers
- rate in
galactomannan: -63. 8%, i.e. a rate of
0.36% compared to fibers.

 Production increased by about 6%, reaching 2,570 kg / hour.

As for the physical characteristics, we arrive at the following equilibrium:
- internal cohesion: 219 J / m2
- burst index: 9.4
- Ring Crush, cross direction: 89.8 daN
- breaking length,
direction of travel: 27.9 N.

 It emerges from these examples that the introduction of humic products or humic derivatives not only makes it possible to reduce the suspended matter in the water under canvas, but that it makes it possible to very significantly increase the productivity of paper machines, while providing a very significant improvement in the characteristics of the paper and cardboard thus prepared.

 These decisive advantages are certainly due to the presence on the molecules of humic products or humic derivatives used in accordance with the invention of a multitude of ionizable carboxylic and hydroxyl functions and of oxygen or nitrogen atoms which donate electrons. . This presence gives humic materials the ability to form complexes with mono and versatile cations. The presence of a strong anionicity of humic materials would thus make it possible to retain and better organize the orientation of the molecules used in the composition of the sheets of paper, by optimizing the cationic bridging responsible for internal cohesion.

 Thus, thanks to the present invention, a person skilled in the art has a completely efficient process for manufacturing paper.

Claims (6)

 1. An improved process for manufacturing paper, characterized in that one adds, at one or more places located in the wet section of the paper machine, an effective amount of at least one humic product or at least a humic derivative.  2. An improved process for manufacturing paper according to claim 1, characterized in that the effective amount of humic product or humic derivative is between 0.005% and 6%, preferably between 0.01% and 5%, and more preferably still between 0.02% and 1%, these percentages being expressed in dry weight of humic matter relative to the dry weight of paper.  3. An improved process for manufacturing paper according to either of claims 1 and 2, characterized in that the humic product or humic derivative is added to the wet section of the paper machine before the sheet of paper does not reach a dryness rate of about 45%, preferably 20% and more preferably still%.  4. An improved process for manufacturing paper according to any one of claims 1 to 3, characterized in that the humic products and derivatives are derived from materials resulting from humification, in particular peat or reoxidized coal.  5. Use of humic product or humic derivative for papermaking.  6. Use according to claim 5, to reduce the rate of suspended matter in the water under canvas, to improve the characteristics of the paper machine, and to increase the physical characteristics of the paper.