CA2466312C - A retention and drainage system recommended for the manufacturing of paper, paperboard, cardboard and other similar products - Google Patents
A retention and drainage system recommended for the manufacturing of paper, paperboard, cardboard and other similar products Download PDFInfo
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- CA2466312C CA2466312C CA2466312A CA2466312A CA2466312C CA 2466312 C CA2466312 C CA 2466312C CA 2466312 A CA2466312 A CA 2466312A CA 2466312 A CA2466312 A CA 2466312A CA 2466312 C CA2466312 C CA 2466312C
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- retention
- stock
- paper
- drainage agent
- drainage
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Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
- D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
- D21H23/765—Addition of all compounds to the pulp
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/06—Paper forming aids
- D21H21/10—Retention agents or drainage improvers
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
- D21H17/24—Polysaccharides
- D21H17/28—Starch
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
- D21H17/375—Poly(meth)acrylamide
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/53—Polyethers; Polyesters
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/71—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes
- D21H17/74—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes of organic and inorganic material
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
- D21H21/20—Wet strength agents
Abstract
A process for manufacturing a paper stock for use in making paper, paperboard and similar cellulosic products, by adding, at one or more different points of the wet end of the paper-making machine, a secondary retention and drainage agent containing a liquid smectite, and a primary retention and drainage agent comprising a natural or synthetic polymer. The retention and drainage agents can be added in any order, thus improving the retention, drainage, formation and drying, without affecting the whiteness, and enhancing the physical values of the paper, paperboard, cardboard and other similar products. The smectite can be an enhanced, concentrated, liquid smectite that can avoid the need for an on-site preparation unit.
Description
DESCRIPTIVE NOTE
The present invention generally refers to the manufactur-ing process of paper, paperboard, cardboard and similar prod-ucts (such as cellulose, fiber cement, etc.) in which, at dif-ferent points of the wet end of the machine, an enhanced, con-centrated, liquid smectite (avoiding herewith the need of an on-site preparation unit) and a natural or synthetic polymer are added.
The said retention and drainage agents can be added in any order, thus improving the retention, drainage, formation and drying, without affecting the whiteness and enhancing the physical values of the paper, paperboard, cardboard and other similar products.
ANTECEDENTS
The retention and drainage systems aim at improving the drainage (the capacity to eliminate water) and the retention of fines and fillers which are part of the paper sheet.
These systems have evolved coming from one retention and drainage agent to two and more components used today. Each one of them shows advantages and disadvantages, while the systems most used are the ones based on microparticles.
The benefits expected from a retention and drainage system are the following:
- higher production (ton/hr);
- lower production costs;
- lower energy consumption;
- better stability and reliability of the production systems;
The present invention generally refers to the manufactur-ing process of paper, paperboard, cardboard and similar prod-ucts (such as cellulose, fiber cement, etc.) in which, at dif-ferent points of the wet end of the machine, an enhanced, con-centrated, liquid smectite (avoiding herewith the need of an on-site preparation unit) and a natural or synthetic polymer are added.
The said retention and drainage agents can be added in any order, thus improving the retention, drainage, formation and drying, without affecting the whiteness and enhancing the physical values of the paper, paperboard, cardboard and other similar products.
ANTECEDENTS
The retention and drainage systems aim at improving the drainage (the capacity to eliminate water) and the retention of fines and fillers which are part of the paper sheet.
These systems have evolved coming from one retention and drainage agent to two and more components used today. Each one of them shows advantages and disadvantages, while the systems most used are the ones based on microparticles.
The benefits expected from a retention and drainage system are the following:
- higher production (ton/hr);
- lower production costs;
- lower energy consumption;
- better stability and reliability of the production systems;
- less acidity in the system due to the decrease of aluminum sulphate and consequently fewer corrosion problems;
- better formation of the paper sheet (seen against the light);
- less porosity of the paper and - less humidity of the paper.
Traditionally the paper machines have worked with reten-tion agents, such as:
- natural polymers such as starch;
- synthetic polymers such as cationic, anionic, amphoteric and non-ionic polyacrylamides and - polyethylene oxide.
These products have the characteristic to "retain" a higher number of solids in suspension (fines and fillers) than the stock on its own without these additives.
Therefore, these days it is common practice in the paper manufacturing industry to use stock retention and drainage aids.
- better formation of the paper sheet (seen against the light);
- less porosity of the paper and - less humidity of the paper.
Traditionally the paper machines have worked with reten-tion agents, such as:
- natural polymers such as starch;
- synthetic polymers such as cationic, anionic, amphoteric and non-ionic polyacrylamides and - polyethylene oxide.
These products have the characteristic to "retain" a higher number of solids in suspension (fines and fillers) than the stock on its own without these additives.
Therefore, these days it is common practice in the paper manufacturing industry to use stock retention and drainage aids.
In the prior art several stock retention and drainage aids are known, such as the polyacrylamides (PAM), polyethylenimines (PEI), polyamides and polyamines, mainly.
Thus, for example, in the US Patent NO 3.052.595 the use of polyacrylamides with filler is described and it is stated that advantageous results are obtained when bentonite provides 1 to 20% by weight of the mineral filler. In the British Patent NO 1.265.496 it is described how polyacrylamides are used to retain organic filler and cellulosic fines but that critical conditions have to be observed for successful operation, and particular modified acrylamides are described.
In the German Patent NO 2262906 it is proposed to improve the dewatering of cellulosic slurries by adding bentonite and a low molecular weight cationic polymer that serves as a poly-electrolyte. In the prior art, the amount of bentonite included in the pulp is generally between 0.02 and 2% by weight dry ben-tonite clay, based on dry weight of paper or pulp, and most preferably it is between 0.1 and 1%. The bentonite-type clay used in the invention may be one of the common commercially available bentonites (known as montmorillonite clays) such as "Wyoming bentonite" and "Fullers Earth", and may or may not be chemically modified, e.g. by alkali treatment to convert the calcium bentonite substantially to alkali (e.g. sodium, potassium or ammonium)bentonite.
Another document related to the subject of the present invention is the US Patent N 4.753.710 granted to the company Allied Colloids in which a process is described according to which a cationic polymer, preferably polyethylenimine, a polyamine epichlorhydrin product, a polymer of diallyl dimethyl ammonium chloride, or a polymer of acrylic monomers is added to a watery cellulosic suspension before the last shearing stage, and bentonite is added after this shearing stage. This process allows for better retention, drainage, drying and web forming properties. The bentonite used in the said process is called "HydrocolTM..
Respectively, according to the paper production method de-scribed in the US Patent NO 5.178.730, granted to the company Delta Chemicals, there is added to the stock before the shear-ing stage a cationic polymer, which is preferably a tertiary or quaternary amine derivative of polyacrylamide, and after the shearing stage, before the head box, there is added a natural hectorite at a weight ration 0.5:1 - 10:1. The method according to this patent can be used in alkaline and acid paper produc-tion processes.
In the US Patent NO 5.876.563, of Allied Colloids, a cati-onic starch together with a cationic polymer and an anionic mi-croparticulate material is used as the retention aid.
On the other hand, according to the Patent WO 99/14432 of Allied Colloids, the microparticulate aid is preferably ben-tonite, silica, a polysilicic acid, polysilicate microgel, or an aluminum-modified version thereof.
The use of silicate microparticles together with a cati-onic polymer in a retention system is described in the US Pat-ent 5.194.120 of Delta Chemicals. The prevalent cation in the synthetic amorphous metal silicate was magnesium, and the poly-mer was preferably a terciary or quaternary amine derivative of polyacrylamide, their weight ratio being between 0.03:1 and 30:1. By this method, retention, dewatering and formation were improved by using smaller amounts of retention aids than previ-ously, and thus the costs were correspondingly lower.
Through the US Patent NO 4.305.781, granted to Allied Col-loids in 1981, the use of a clay in combination with a syn-thetic polymer was introduced. Today this is known as the dual system (two components) or microparticulate system (particle size between nanometers and micrometers).
The combination and the adding order - first clay then polymer - increased drainage and retention. This patent was based on a non-ionic linear polymer.
Here below this and other systems of the prior art and their disadvantages will be described in detail:
The so-called ORGANOPOLT' system, described in Patent N EP-A-0 235893, granted in the year 1979, consisted of two chemical products:
a) ORGANOSORBI, which is an activated or modified bentonite, an inorganic pigment in powder, which is added as a slurry at 1.5 - 5% by weight in concentration, preferably 2.5% by weight to the level box. In the prior art, an automatic unit for the preparation of the dispersion of the bentonite in powder was used, an on-line continuous process, that is, not by batch, generating the following problems:
no adequate swelling is produced, that is, no de-lamination of the bentonite is produced, since the dispersion residence time in the automatic bentonite preparation equipment is very short. Therefore the bentonite does not increase the retention capacity of the colloidal and semi-colloidal particles of organic and inorganic compounds present in the stock the pa-per, paperboard, cardboard and other similar products are made with;
- there are variations in the concentration of the ben-tonite dispersion added to the stock system the pa-per, paperboard, cardboard and other similar products are made with;
the required equipment of continuous preparation is very big, complex, difficult to operate and handle and has a very high cost, (US $ 80.000);
the concentrations of bentonite above 5% by weight form very viscous, gel-like dispersions difficult to pump;
b) The ORGANOPOL polymer, which is an essentially linear cationic polyacrylamide with molecular weights of more than one million, three million and higher (according to Patent NO EP-A-0 235893) is added to the thin, diluted stock, after the pressure screen.
The polymer added at this point, does not allow to reduce the size of the floccules, no smaller, tougher and more uniform floccules are obtained, and therefore there is no good forma-tion of the paper, paperboard or cardboard sheet.
The ORGANOPOL system presents the following disadvantages:
loss of whiteness, with the consequent increase of the use of optical whiteners, the adverse impact of the retention and drainage and the complex handling of the bentonite.
Afterwards, in the US Patent NO 4.753.710 (corresponding to the Hydrocol process), granted in the year 1988, basically the same idea is presented, apart from the fact that the order of adding the two products to the machine is inverted, that is, first the polymer is added, and then the clay (a bentonite).
That patent is based on cationic linear polymers of high molecular weight before a shearing stage, and after the shear-ing stage the clay (bentonite) is added. Preferably at the last shearing point, which is the pressure screen.
It is important to point out that both patents, but espe-cially the last one, make a big distinction at the shearing point. Additionally it focuses on a very specific type of poly-mer.
This system, known as Hydrocol, presents several problems:
- Necessity of an on-site preparation equipment of high cost, approx. US$ 80.000;
- poor hydration of the bentonite (the maximum levels are not achieved);
- high consumption of the product (2 to 6 kilos per ton of pa-per) ;
- high energy consumption;
- more complex operation;
- loss of whiteness and - excessive retention with a negative effect on the drainage.
Until today many dual systems have been presented, with the same objectives, but none have been able to overcome these inconveniences. Currently, the company CIBA, owner of several patents, should represent more than 50% of the systems used in paper plants in the world.
To give complete information, the existing systems are presented here below in a table explaining the basic operation principles:
System Component 1 Component 2 Component 3 ParticolTM Cationic Colloidal (CIBA) polyacrylamide silica PoliflexTM Cationic Inverse (CIBA) polyacrylamide anionic micro-emulsion ComposilTM Cationic Polysilicic (EKA) starch with acid high substitu-tion degree PositekTM Cationic co- High molecular Borosilicate (Nalco) agulant weight floccu-lant MosaicTM (Buck- Coagulant Polyacrylamide Microparticle man) (4 alterna-tives) The before mentioned systems of the prior art present some advantages and disadvantages to be mentioned hereafter:
ParticolTM has the advantage of using low application doses and its on-site preparation diminishes the possibility of losing effectiveness. The counterpart is the complex equipment at the client's plant.
ComposilTM is a system which has good retention and drainage results, does not effect the strength properties and does not have any impact on the consumption of optical whiteners.
However, the problem is that it is only effective in alkaline sys-tems, it is expensive and good control must be kept on the dose (equipment).
Positek and Mosaic systems need more components, and therefore have more equipment and variables to control; they are more complex systems.
These and other inconveniences of the procedures of the prior art have been solved through the present invention, a detailed description of which will follow hereafter.
DETAILED DESCRIPTION OF THE INVENTION
In view of the problems generated by the before described systems, we have developed the following system:
According to the present invention a new retention and drainage system was developed, called "TOP DUAL'", recommended for the manufacturing of paper, paperboard, cardboard and other similar products, for acid, neutral and alkaline environments, in which basically two products or chemical compositions are added to the paper stock:
a) A liquid secondary retention and drainage agent, called VERSINQUI A-250TM, with which the necessity of an expensive on-site preparation equipment is eliminated and b) A primary retention and drainage agent, called VERSINQUITM;
This flexible system, when compared to the ones described above, succeeds in improving the process of drainage, retention, the formation of the sheet and the drying, increasing the physical parameters and does not negatively affect the whiteness of the paper, cardboard, paperboard and other similar products.
Traditionally the polymers have been considered primary or of more importance to the process of manufacturing paper, paperboard and cardboard for the retention, drainage and formation. The microparticulate, dual and even trial (3 components) systems have come and presented an improvement regarding these variables and have been secondary to the principal (polymer).
In the present invention we have wanted to underline the significant contribution of the microparticle which is respon-sible for the main improvement of the system. That is the rea-son why in the first place the product VERSINQUI A-250 is elaborated on, which, even though traditionally called "secon-dary" agent, brings about more improvement than the VERSINQUI, traditionally called "primary" agent.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 shows in a drawing the stream of a plant where paper, paperboard, cardboard or other similar products (such as cellulose, fiber cement etc.) are manufactured, including the adding points for the treatment of retention and drainage of the present invention and Figure 2 shows in a drawing the molecular structures of synthetic polymers used as retention agents. In figure 2, a represents a molecular structure of linear polymers, b repre-sents a molecular structure of branched polymers and c repre-sents a molecular structure of cross-linked polymers.
In particular, Figure 1 shows the following treatment equipments relevant from retention and drainage treatment point of view, including the points where the products of the present invention can be added:
a) refined or non-refined stock tank (la);
b) refined or non-refined stock tank pump(lb);
c) refiner (2) ;
d) level box (3) ;
e) stock pump feeding the depuration stage (4);
f) other depuration stages (5);
g) feeding at the first stock depuration stage (6);
h) arrival of the stock of the first stock depuration stage (7) ;
i) feeding of the dilution water before the depurated stock enters (8);
j) fan pump (9) ;
k) entry of the pressure screen (10a);
1) interior of the pressure screen (l0b);
m) exit of the pressure screen (10c) and n) head box (11).
When referring to Figure 1 in particular, it indicates the preferable points where the retention and drainage agents cor-responding to the TOP DUAL system of the present invention should be added.
In particular, the novel secondary retention and drainage agent, VERSINQUI A-250, consists of a liquid formula, manufac-tured by the supplier, capable of being introduced via a pump and which contains as one of its main ingredients a smectite or a chemically modified version thereof, preferably a normal, ac-tivated or modified bentonite with a concentration in the for-mula higher than 6.5% by weight of the dispersion. This secon-dary formula allows, among other things, to strongly increase the specific, superficial area of the before mentioned smectite with which the retention capacity of fines, colloidal parti-cles, semi-colloidal particles, organic and inorganic compounds present in the paper stock with which paper, paperboard, card-board and other similar products are manufactured, is improved.
Once the secondary agent VERSINQUI A-250 is added to the stock, it modifies the stock, which is flocculated by the action of the second component, called primary retention and drainage agent VERSINQUI.
In contrast with the adding of the before mentioned prod-uct ORGANOSORB supplied by the company CIBA, consisting of a bentonite slurry of less than 5% by weight, preferably 2.5% by weight of the bentonite in the dispersion, which is added to the level box (3), the secondary retention and drainage agent, VERSINQUI A-250, of the present invention can be added to the paper machine in the following points of the process, indicated in Figure 1:
a) at the suction of the stock tank pump (lb);
b) at the level box (3);
c) at the suction of the stock pump feeding the stock depu-ration stage (4);
d) at other paper stock depuration stages (5);
e) to accepted of the first stage of stock depuration (6);
f) at the dilution water before the entry of the depurated stock (8);
g) before the fan pump (9) ;
h) before the pressure screen (10a);
i) inside the pressure screen (lob) and j) after the pressure screen (10c).
In particular, the secondary retention and drainage agent, object of the present invention, the novel liquid product VERS-INQUI A-250, more easily retains the organic and inorganic com-pounds present in the stock the paper, paperboard, cardboard and other similar products (cellulose, fiber cement, etc.) are manufactured with, such as fines, fillers, glues, starch, lign-ine and hemicelluloses.
Adding the secondary retention and drainage agent of the present invention VERSINQUI A-2501" before the fan pump and the primary retention and drainage agent VERSINQUIT", consisting of a linear, branched or cross-linked polyacrylamide apart from starches, polyethylene oxides, dry strength resins, wet strength resins, organic and inorganic coagulants and other polymers, before and inside the pressure screen (10a, 10b) of the paper machine allow to obtain a higher general first-pass retention in the said machines.
Apart from that, adding the secondary retention and drainage agent VERSINQUI A-250'" and the primary retention and drainage agent VERSINQUIT" at the indicated points of the paper machine allows to obtain smaller, tougher and more uniform floccules, with which a better formation of the paper sheet is obtained and it allows to enhance the physical parameters of the paper, paperboard, cardboard and other similar products, such as the longitudinal strength, the transversal strength, CMT, ring crush, Cobb, Mullen explosion, Denisson, etc.
Apart from that, through this system (process) the prod-ucts added at the indicated points of the paper machine allow to increase the retention of the said paper machine with which a decrease in the consistence, and in the level of solids sus-pended in the "white water", in the water under the wire and the vats, is achieved.
Additionally, adding the secondary retention and drainage agent VERSINQUI A-250 and the primary retention and drainage agent VERSINQUI at the indicated points of the paper machine allows to work with lower consistences in the head box (11) of the paper machine, with which, among other things, a better distribution of the fibers in the wet sheet being formed on the wire or the vats is achieved.
Moreover, adding the secondary retention and drainage agent VERSINQUI A-250 and the primary retention and drainage agent VERSINQUI according to the present invention, allows to increase the drainage capacity of the paper stock, to produce a dryer sheet at the end of the wire or the vats, with which a substantial saving in the consumption of steam is achieved, apart from increasing the speed and with this the production of the paper machine and maintaining, moreover, the stability thereof.
Through the TOP DUAL retention and drainage system of the present invention it is possible to decrease the levels of dos-age of the chemical product VERSINQUI A-250 to 150 g/ton of pa-per, equivalent to 40 g of smectite per ton/paper, and the polymer VERSINQUI to 50 g/ton paper, obtaining high levels of retention and drainage of the fiber very superior to those of the systems described in the prior art, for example the one called ORGANOPOL. With these before mentioned dosage levels a considerable saving in consumption and the consequent costs of the chemical products of the TOP DUAL retention and drainage system in the paper machine according to the invention is achieved.
The preferable dosage level of the secondary retention and drainage agent according to the invention, VERSINQUI A-250, consisting of a pumpable liquid formula prepared in the chemi-cal product suppliers's plant, lies between 150 and 1.000 g/ton of paper; however, the dosage of the formula of the prior art consisting of a powder bentonite (ORGANOPOL system) lies be-tween 2.000 and 6.000 g/ton of paper, where, moreover, in this last case a very big and expensive unit is used in the continu-ous process of the preparation of the bentonite dispersion. The said dosage of the retention and drainage agents VERSINQUI A-250/VERSINQUI according to the invention allows to improve the quality of the manufactured paper, complying with all the tech-nical specifications and quality standards of the product manu-factured in the paper machine.
In relation to the prior art, in particular the ORGANOPOL
product of the company CIBA consists of a linear cationic poly-acrylamide described in the patent NO EP-A-0 235893, granted in the year 1979, is applied in the dual retention system OR-GANOPOL and is added to the thin, diluted paper stock after the last point of major shearing of the machine, that is after the pressure screen (10c) and flocculates the modified stock. How-ever, the primary retention and drainage agent of the present invention, VERSINQUI, consisting of a linear, branched or cross-linked polyacrylamide, apart from starches, polyethylene oxides, dry strength resins, wet strength resins, organic and inorganic coagulants and other polymers, can be added before and inside the pressure screen (10a, 10b) to allow, in the first place, for the formation of big floccules in the modified stock, which, while passing through the before mentioned pres-sure screen, form smaller, tougher and more uniform floccules, with which a better formation of the sheet of paper, paper-board, cardboard or other similar product without lumps in the stock is achieved. In the process of the present invention it is also possible to add the primary retention and drainage agent VERSINQUI after the pressure screen (10c).
Another advantage of the present invention through the process of adding VERSINQUI at the indicated adding points, is that it allows to reduce the tearing of the paper sheets and, consequently, to increase the productivity of the paper ma-chine, reducing, moreover, the solids in suspension at the ef-fluent of the machine or plant.
Another advantage of the invention lies in the fact that adding the retention agent VERSINQUI at the indicated points of the paper machine allows to reduce the dosages of starch, glue and other chemical agents, maintaining the values within the standard, reducing the BOD and COD indexes at the effluent of the paper machine with the consequent advantages from environ-mental contamination point of view.
Thanks to the retention and drainage agents and the system of adding thereof according to the present invention, it is possible to use more recycled fibers in the paper machine.
Finally, the system of the present invention allows to work in acid, neutral or alkaline environments and does not af-fect the whiteness of the paper.
The before mentioned primary retention and drainage agent VERSINQUI, which is a linear, branched or cross-linked poly-acrylamide or a starch, polyethylene oxide (PEO), dry strength resin, wet strength resin, organic or inorganic coagulant or another polymer, flocculates the stock.
Adding the primary retention and drainage agent VERSINQUI
according to the invention can be done at the following points of the paper machine:
a) between the stages of the manufacturing process of paper, paperboard, cardboard (la) and (10c) of the stock stream of Figure 1 and preferably at the following points:
- before the fan pump (9);
- before the pressure screen (10a);
- inside the pressure screen (10b);
- after the pressure screen (10c).
The primary retention and drainage agent VERSINQUI can be formed by the following components:
- linear, branched or cross-linked polyacrylamides;
- starches;
- polyethylene oxides;
- dry strength and wet strength resins;
- organic and inorganic coagulants and - other polymers.
The before mentioned primary retention and drainage agent is preferably prepared in the client's plant. If the ingredi-ents are solid products, then the dissolution thereof is effec-tuated in an automatic powder dissolution unit, and if they are liquids, then it is effectuated by means of an on-line dosage pump. The dosage range of the primary retention agent lies be-tween 50 and 10.000 g/ton of paper.
ADDING STAGES
A) The first stage for adding the chemical products of the re-tention and drainage system called TOP DUAL according to the present invention is developed in the refined or non-refined stock tank (la) . This refined or non-refined stock is the re-sult of the disintegration of the fibrous material: rags of cellulose, waste paper and brokers, etc., produced in the so-called "helix" or "pulper" according to a production schedule.
This fibrous material converted in stock and after going through the depuration stages, screens, etc., arrives at the refined or non-refined stock tank (la).
At the suction of the stock pump (ib) of this refined or non-refined stock tank (la), as first adding point, a liquid chemical composition with retention and drainage properties ac-cording to the invention is added. This chemical composition corresponds to the product VERSINQUI A-250, secondary retention and drainage agent.
This stock with the agent VERSINQUI A-250 goes to the fan pump (9), pressure screen (10) and then to the head box (11).
There are nine other possible points of adding, mentioned be-fore, adequate for introducing the agent VERSINQUI A-250 to the paper stock to manufacture paper, paperboard, cardboard and similar products.
Adding the secondary agent VERSINQUI A-250, which is a liquid, pumpable product, manufactured in the plant of the sup-plier and which contains a smectite or a chemically modified version thereof, preferably a normal, activated or modified bentonite, is very easy, since it is preferably distributed in containers of 1.000 kg and a variable caudal pump is sufficient to adequately add this product. It is a simple installation: on a container, a second container is installed on a stand with the 1.000 kg of VERSINQUI A-250 product which is unloaded ac-cording to what the lower container consumes. Finally, during the course of the days, what is left inside the upper container is emptied and the container is changed. The lower container is connected to the dosage pump.
This first liquid composition, corresponding to the secon-dary retention and drainage agent called VERSINQUI A-250 has the following chemical formula:
General formula:
Water (from 5 to approx. 950 C): 0 - 92%, by weight;
Dispersing agent: 1 - 80%, by weight and Smectite (clay): 8 - 50% by weight.
Application example:
Warm water (40 - 60 C): 66.4%, by weight;
Sodium polyacrylate: 9.1% by weight and Smectite (clay): 24.5% by weight (preferably mont-morillonite).
The preparation of this first liquid composition of the secondary agent VERSINQUI A-250, prepared in the supplier's plant, allows for a de-lamination of the smectite (clay) and, therefore, the specific, superficial area of the smectite is strongly increased, with which an increase in the retention of fines, colloidal particles, semi-colloidal particles of the or-ganic and inorganic compounds present in the paper stock for the manufacturing of paper, paperboard, cardboard and other similar products, is achieved and this thus modified stock is flocculated by the second component, the so-called primary re-tention and drainage agent.
The pumpable liquid chemical composition of the secondary retention and drainage agent VERSINQUI A-250 according to the invention allows to concentrate the smectite clay 6.5% by weight in the watery dispersion, situation not one single sys-tem in use in the world currently achieves.
The dosage controlled via a pump with variable caudal of the VERSINQUI A-250 lies preferable between 150 and 1.000 g/ton of final produced paper. The dispersing agent of the before mentioned formula is preferably a sodium polyacrylate. However, it is also possible to formulate the product VERSINQUI A-250 with other dispersing agents different from sodium polyacry-late:
a) organic salts of alquil-aril-sulphonic acids;
b) purified sulpholignine;
c) extracts from seaweed;
d) condensed proteins and fatty acids;
e) sulphonate esters;
f) high molecular weight alquil sulphate sodium salts;
g) polycarboxilic compounds;
h) phosphates: hexametaphosphates, pyrophosphates, tripoly-phosphates, etc.;
i) sodium salt of polyaspartic acid;
j) alcohol;
k) acetone y 1) glycerin.
B) The second stage of the method according to the invention comprises adding the liquid composition or chemical product, called primary retention and drainage agent or VERSINQUI, which can be a:
- linear, branched or cross-linked polyacrylamide;
- starch;
- polyethylene oxide;
- dry strength and wet strength resin;
- organic and inorganic coagulant and - other polymer.
The adding points of the before mentioned primary retention agent can be between the positions la to 10c of the stream drawing of Figure 1. Adding the primary retention and drainage agent VERSINQUI is preferably done at the following points:
a) before the fan pump (9) ;
b) before the pressure screen (loa);
c) inside the pressure screen (lob) y a) after the pressure screen (10c).
The preparation and adding of the primary retention and drainage agent is preferably in the paper factory of the cli-ent. If the products are solid, then the dissolution is done in an automatic powder dissolution unit and if they are liquids, it is done by means of an on-line dilution dosing pump.
The dosage range of the primary retention and drainage agent lies between 50 and 10.000 g/ton final paper.
Contrarily to what is explained before, in the adding sys-tem described in the prior art, through the ORGANOPOL system of the company CIBA, the recommended adding points are the follow-ing:
a) adding ORGANOSORB, bentonite dispersion, at the level box (3) and b) adding ORGANOPOL, linear polyacrylamide, after the pres-sure screen (10c).
Generally, in the process of the present invention, the sequence of adding the two chemical compositions or the chemi-cal products can be done indistinctly; that is, first the sec-ondary retention and drainage agent and then the primary, or vice versa, first the primary retention and drainage agent and then the secondary. Additionally, in some cases the secondary retention and drainage agent can be used without the primary retention and drainage agent.
Here below the adding points of the TOP DUAL retention and drainage system according to the invention are summed up, re-ferring to Figure 1:
1)VERSINQUI A-250, secondary retention and drainage agent:
a) at the suction of the stock tank pump (1b);
b) at the level box (3);
c) at the suction of the stock pump feeding the stock depu-ration stage (4);
d) at other paper stock depuration stages (5);
e) to accepted of the first stage of stock depuration (6);
f) at the dilution water before the entry of the depurated stock (8) ;
g) before the fan pump (9) ;
h) before the pressure screen (loa);
i) inside the pressure screen (lob) and j) after the pressure screen (loc).
2)VERSINQUI, primary retention and drainage agent, between the stages of the process of manufacturing paper, paperboard, cardboard or other similar products from item la to 10c of Fig-ure 1, but preferably:
a) before the fan pump (9) ;
b) before the pressure screen (loa);
c) inside the pressure screen (lob) y d) after the pressure screen (10c).
Thus, for example, in the US Patent NO 3.052.595 the use of polyacrylamides with filler is described and it is stated that advantageous results are obtained when bentonite provides 1 to 20% by weight of the mineral filler. In the British Patent NO 1.265.496 it is described how polyacrylamides are used to retain organic filler and cellulosic fines but that critical conditions have to be observed for successful operation, and particular modified acrylamides are described.
In the German Patent NO 2262906 it is proposed to improve the dewatering of cellulosic slurries by adding bentonite and a low molecular weight cationic polymer that serves as a poly-electrolyte. In the prior art, the amount of bentonite included in the pulp is generally between 0.02 and 2% by weight dry ben-tonite clay, based on dry weight of paper or pulp, and most preferably it is between 0.1 and 1%. The bentonite-type clay used in the invention may be one of the common commercially available bentonites (known as montmorillonite clays) such as "Wyoming bentonite" and "Fullers Earth", and may or may not be chemically modified, e.g. by alkali treatment to convert the calcium bentonite substantially to alkali (e.g. sodium, potassium or ammonium)bentonite.
Another document related to the subject of the present invention is the US Patent N 4.753.710 granted to the company Allied Colloids in which a process is described according to which a cationic polymer, preferably polyethylenimine, a polyamine epichlorhydrin product, a polymer of diallyl dimethyl ammonium chloride, or a polymer of acrylic monomers is added to a watery cellulosic suspension before the last shearing stage, and bentonite is added after this shearing stage. This process allows for better retention, drainage, drying and web forming properties. The bentonite used in the said process is called "HydrocolTM..
Respectively, according to the paper production method de-scribed in the US Patent NO 5.178.730, granted to the company Delta Chemicals, there is added to the stock before the shear-ing stage a cationic polymer, which is preferably a tertiary or quaternary amine derivative of polyacrylamide, and after the shearing stage, before the head box, there is added a natural hectorite at a weight ration 0.5:1 - 10:1. The method according to this patent can be used in alkaline and acid paper produc-tion processes.
In the US Patent NO 5.876.563, of Allied Colloids, a cati-onic starch together with a cationic polymer and an anionic mi-croparticulate material is used as the retention aid.
On the other hand, according to the Patent WO 99/14432 of Allied Colloids, the microparticulate aid is preferably ben-tonite, silica, a polysilicic acid, polysilicate microgel, or an aluminum-modified version thereof.
The use of silicate microparticles together with a cati-onic polymer in a retention system is described in the US Pat-ent 5.194.120 of Delta Chemicals. The prevalent cation in the synthetic amorphous metal silicate was magnesium, and the poly-mer was preferably a terciary or quaternary amine derivative of polyacrylamide, their weight ratio being between 0.03:1 and 30:1. By this method, retention, dewatering and formation were improved by using smaller amounts of retention aids than previ-ously, and thus the costs were correspondingly lower.
Through the US Patent NO 4.305.781, granted to Allied Col-loids in 1981, the use of a clay in combination with a syn-thetic polymer was introduced. Today this is known as the dual system (two components) or microparticulate system (particle size between nanometers and micrometers).
The combination and the adding order - first clay then polymer - increased drainage and retention. This patent was based on a non-ionic linear polymer.
Here below this and other systems of the prior art and their disadvantages will be described in detail:
The so-called ORGANOPOLT' system, described in Patent N EP-A-0 235893, granted in the year 1979, consisted of two chemical products:
a) ORGANOSORBI, which is an activated or modified bentonite, an inorganic pigment in powder, which is added as a slurry at 1.5 - 5% by weight in concentration, preferably 2.5% by weight to the level box. In the prior art, an automatic unit for the preparation of the dispersion of the bentonite in powder was used, an on-line continuous process, that is, not by batch, generating the following problems:
no adequate swelling is produced, that is, no de-lamination of the bentonite is produced, since the dispersion residence time in the automatic bentonite preparation equipment is very short. Therefore the bentonite does not increase the retention capacity of the colloidal and semi-colloidal particles of organic and inorganic compounds present in the stock the pa-per, paperboard, cardboard and other similar products are made with;
- there are variations in the concentration of the ben-tonite dispersion added to the stock system the pa-per, paperboard, cardboard and other similar products are made with;
the required equipment of continuous preparation is very big, complex, difficult to operate and handle and has a very high cost, (US $ 80.000);
the concentrations of bentonite above 5% by weight form very viscous, gel-like dispersions difficult to pump;
b) The ORGANOPOL polymer, which is an essentially linear cationic polyacrylamide with molecular weights of more than one million, three million and higher (according to Patent NO EP-A-0 235893) is added to the thin, diluted stock, after the pressure screen.
The polymer added at this point, does not allow to reduce the size of the floccules, no smaller, tougher and more uniform floccules are obtained, and therefore there is no good forma-tion of the paper, paperboard or cardboard sheet.
The ORGANOPOL system presents the following disadvantages:
loss of whiteness, with the consequent increase of the use of optical whiteners, the adverse impact of the retention and drainage and the complex handling of the bentonite.
Afterwards, in the US Patent NO 4.753.710 (corresponding to the Hydrocol process), granted in the year 1988, basically the same idea is presented, apart from the fact that the order of adding the two products to the machine is inverted, that is, first the polymer is added, and then the clay (a bentonite).
That patent is based on cationic linear polymers of high molecular weight before a shearing stage, and after the shear-ing stage the clay (bentonite) is added. Preferably at the last shearing point, which is the pressure screen.
It is important to point out that both patents, but espe-cially the last one, make a big distinction at the shearing point. Additionally it focuses on a very specific type of poly-mer.
This system, known as Hydrocol, presents several problems:
- Necessity of an on-site preparation equipment of high cost, approx. US$ 80.000;
- poor hydration of the bentonite (the maximum levels are not achieved);
- high consumption of the product (2 to 6 kilos per ton of pa-per) ;
- high energy consumption;
- more complex operation;
- loss of whiteness and - excessive retention with a negative effect on the drainage.
Until today many dual systems have been presented, with the same objectives, but none have been able to overcome these inconveniences. Currently, the company CIBA, owner of several patents, should represent more than 50% of the systems used in paper plants in the world.
To give complete information, the existing systems are presented here below in a table explaining the basic operation principles:
System Component 1 Component 2 Component 3 ParticolTM Cationic Colloidal (CIBA) polyacrylamide silica PoliflexTM Cationic Inverse (CIBA) polyacrylamide anionic micro-emulsion ComposilTM Cationic Polysilicic (EKA) starch with acid high substitu-tion degree PositekTM Cationic co- High molecular Borosilicate (Nalco) agulant weight floccu-lant MosaicTM (Buck- Coagulant Polyacrylamide Microparticle man) (4 alterna-tives) The before mentioned systems of the prior art present some advantages and disadvantages to be mentioned hereafter:
ParticolTM has the advantage of using low application doses and its on-site preparation diminishes the possibility of losing effectiveness. The counterpart is the complex equipment at the client's plant.
ComposilTM is a system which has good retention and drainage results, does not effect the strength properties and does not have any impact on the consumption of optical whiteners.
However, the problem is that it is only effective in alkaline sys-tems, it is expensive and good control must be kept on the dose (equipment).
Positek and Mosaic systems need more components, and therefore have more equipment and variables to control; they are more complex systems.
These and other inconveniences of the procedures of the prior art have been solved through the present invention, a detailed description of which will follow hereafter.
DETAILED DESCRIPTION OF THE INVENTION
In view of the problems generated by the before described systems, we have developed the following system:
According to the present invention a new retention and drainage system was developed, called "TOP DUAL'", recommended for the manufacturing of paper, paperboard, cardboard and other similar products, for acid, neutral and alkaline environments, in which basically two products or chemical compositions are added to the paper stock:
a) A liquid secondary retention and drainage agent, called VERSINQUI A-250TM, with which the necessity of an expensive on-site preparation equipment is eliminated and b) A primary retention and drainage agent, called VERSINQUITM;
This flexible system, when compared to the ones described above, succeeds in improving the process of drainage, retention, the formation of the sheet and the drying, increasing the physical parameters and does not negatively affect the whiteness of the paper, cardboard, paperboard and other similar products.
Traditionally the polymers have been considered primary or of more importance to the process of manufacturing paper, paperboard and cardboard for the retention, drainage and formation. The microparticulate, dual and even trial (3 components) systems have come and presented an improvement regarding these variables and have been secondary to the principal (polymer).
In the present invention we have wanted to underline the significant contribution of the microparticle which is respon-sible for the main improvement of the system. That is the rea-son why in the first place the product VERSINQUI A-250 is elaborated on, which, even though traditionally called "secon-dary" agent, brings about more improvement than the VERSINQUI, traditionally called "primary" agent.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 shows in a drawing the stream of a plant where paper, paperboard, cardboard or other similar products (such as cellulose, fiber cement etc.) are manufactured, including the adding points for the treatment of retention and drainage of the present invention and Figure 2 shows in a drawing the molecular structures of synthetic polymers used as retention agents. In figure 2, a represents a molecular structure of linear polymers, b repre-sents a molecular structure of branched polymers and c repre-sents a molecular structure of cross-linked polymers.
In particular, Figure 1 shows the following treatment equipments relevant from retention and drainage treatment point of view, including the points where the products of the present invention can be added:
a) refined or non-refined stock tank (la);
b) refined or non-refined stock tank pump(lb);
c) refiner (2) ;
d) level box (3) ;
e) stock pump feeding the depuration stage (4);
f) other depuration stages (5);
g) feeding at the first stock depuration stage (6);
h) arrival of the stock of the first stock depuration stage (7) ;
i) feeding of the dilution water before the depurated stock enters (8);
j) fan pump (9) ;
k) entry of the pressure screen (10a);
1) interior of the pressure screen (l0b);
m) exit of the pressure screen (10c) and n) head box (11).
When referring to Figure 1 in particular, it indicates the preferable points where the retention and drainage agents cor-responding to the TOP DUAL system of the present invention should be added.
In particular, the novel secondary retention and drainage agent, VERSINQUI A-250, consists of a liquid formula, manufac-tured by the supplier, capable of being introduced via a pump and which contains as one of its main ingredients a smectite or a chemically modified version thereof, preferably a normal, ac-tivated or modified bentonite with a concentration in the for-mula higher than 6.5% by weight of the dispersion. This secon-dary formula allows, among other things, to strongly increase the specific, superficial area of the before mentioned smectite with which the retention capacity of fines, colloidal parti-cles, semi-colloidal particles, organic and inorganic compounds present in the paper stock with which paper, paperboard, card-board and other similar products are manufactured, is improved.
Once the secondary agent VERSINQUI A-250 is added to the stock, it modifies the stock, which is flocculated by the action of the second component, called primary retention and drainage agent VERSINQUI.
In contrast with the adding of the before mentioned prod-uct ORGANOSORB supplied by the company CIBA, consisting of a bentonite slurry of less than 5% by weight, preferably 2.5% by weight of the bentonite in the dispersion, which is added to the level box (3), the secondary retention and drainage agent, VERSINQUI A-250, of the present invention can be added to the paper machine in the following points of the process, indicated in Figure 1:
a) at the suction of the stock tank pump (lb);
b) at the level box (3);
c) at the suction of the stock pump feeding the stock depu-ration stage (4);
d) at other paper stock depuration stages (5);
e) to accepted of the first stage of stock depuration (6);
f) at the dilution water before the entry of the depurated stock (8);
g) before the fan pump (9) ;
h) before the pressure screen (10a);
i) inside the pressure screen (lob) and j) after the pressure screen (10c).
In particular, the secondary retention and drainage agent, object of the present invention, the novel liquid product VERS-INQUI A-250, more easily retains the organic and inorganic com-pounds present in the stock the paper, paperboard, cardboard and other similar products (cellulose, fiber cement, etc.) are manufactured with, such as fines, fillers, glues, starch, lign-ine and hemicelluloses.
Adding the secondary retention and drainage agent of the present invention VERSINQUI A-2501" before the fan pump and the primary retention and drainage agent VERSINQUIT", consisting of a linear, branched or cross-linked polyacrylamide apart from starches, polyethylene oxides, dry strength resins, wet strength resins, organic and inorganic coagulants and other polymers, before and inside the pressure screen (10a, 10b) of the paper machine allow to obtain a higher general first-pass retention in the said machines.
Apart from that, adding the secondary retention and drainage agent VERSINQUI A-250'" and the primary retention and drainage agent VERSINQUIT" at the indicated points of the paper machine allows to obtain smaller, tougher and more uniform floccules, with which a better formation of the paper sheet is obtained and it allows to enhance the physical parameters of the paper, paperboard, cardboard and other similar products, such as the longitudinal strength, the transversal strength, CMT, ring crush, Cobb, Mullen explosion, Denisson, etc.
Apart from that, through this system (process) the prod-ucts added at the indicated points of the paper machine allow to increase the retention of the said paper machine with which a decrease in the consistence, and in the level of solids sus-pended in the "white water", in the water under the wire and the vats, is achieved.
Additionally, adding the secondary retention and drainage agent VERSINQUI A-250 and the primary retention and drainage agent VERSINQUI at the indicated points of the paper machine allows to work with lower consistences in the head box (11) of the paper machine, with which, among other things, a better distribution of the fibers in the wet sheet being formed on the wire or the vats is achieved.
Moreover, adding the secondary retention and drainage agent VERSINQUI A-250 and the primary retention and drainage agent VERSINQUI according to the present invention, allows to increase the drainage capacity of the paper stock, to produce a dryer sheet at the end of the wire or the vats, with which a substantial saving in the consumption of steam is achieved, apart from increasing the speed and with this the production of the paper machine and maintaining, moreover, the stability thereof.
Through the TOP DUAL retention and drainage system of the present invention it is possible to decrease the levels of dos-age of the chemical product VERSINQUI A-250 to 150 g/ton of pa-per, equivalent to 40 g of smectite per ton/paper, and the polymer VERSINQUI to 50 g/ton paper, obtaining high levels of retention and drainage of the fiber very superior to those of the systems described in the prior art, for example the one called ORGANOPOL. With these before mentioned dosage levels a considerable saving in consumption and the consequent costs of the chemical products of the TOP DUAL retention and drainage system in the paper machine according to the invention is achieved.
The preferable dosage level of the secondary retention and drainage agent according to the invention, VERSINQUI A-250, consisting of a pumpable liquid formula prepared in the chemi-cal product suppliers's plant, lies between 150 and 1.000 g/ton of paper; however, the dosage of the formula of the prior art consisting of a powder bentonite (ORGANOPOL system) lies be-tween 2.000 and 6.000 g/ton of paper, where, moreover, in this last case a very big and expensive unit is used in the continu-ous process of the preparation of the bentonite dispersion. The said dosage of the retention and drainage agents VERSINQUI A-250/VERSINQUI according to the invention allows to improve the quality of the manufactured paper, complying with all the tech-nical specifications and quality standards of the product manu-factured in the paper machine.
In relation to the prior art, in particular the ORGANOPOL
product of the company CIBA consists of a linear cationic poly-acrylamide described in the patent NO EP-A-0 235893, granted in the year 1979, is applied in the dual retention system OR-GANOPOL and is added to the thin, diluted paper stock after the last point of major shearing of the machine, that is after the pressure screen (10c) and flocculates the modified stock. How-ever, the primary retention and drainage agent of the present invention, VERSINQUI, consisting of a linear, branched or cross-linked polyacrylamide, apart from starches, polyethylene oxides, dry strength resins, wet strength resins, organic and inorganic coagulants and other polymers, can be added before and inside the pressure screen (10a, 10b) to allow, in the first place, for the formation of big floccules in the modified stock, which, while passing through the before mentioned pres-sure screen, form smaller, tougher and more uniform floccules, with which a better formation of the sheet of paper, paper-board, cardboard or other similar product without lumps in the stock is achieved. In the process of the present invention it is also possible to add the primary retention and drainage agent VERSINQUI after the pressure screen (10c).
Another advantage of the present invention through the process of adding VERSINQUI at the indicated adding points, is that it allows to reduce the tearing of the paper sheets and, consequently, to increase the productivity of the paper ma-chine, reducing, moreover, the solids in suspension at the ef-fluent of the machine or plant.
Another advantage of the invention lies in the fact that adding the retention agent VERSINQUI at the indicated points of the paper machine allows to reduce the dosages of starch, glue and other chemical agents, maintaining the values within the standard, reducing the BOD and COD indexes at the effluent of the paper machine with the consequent advantages from environ-mental contamination point of view.
Thanks to the retention and drainage agents and the system of adding thereof according to the present invention, it is possible to use more recycled fibers in the paper machine.
Finally, the system of the present invention allows to work in acid, neutral or alkaline environments and does not af-fect the whiteness of the paper.
The before mentioned primary retention and drainage agent VERSINQUI, which is a linear, branched or cross-linked poly-acrylamide or a starch, polyethylene oxide (PEO), dry strength resin, wet strength resin, organic or inorganic coagulant or another polymer, flocculates the stock.
Adding the primary retention and drainage agent VERSINQUI
according to the invention can be done at the following points of the paper machine:
a) between the stages of the manufacturing process of paper, paperboard, cardboard (la) and (10c) of the stock stream of Figure 1 and preferably at the following points:
- before the fan pump (9);
- before the pressure screen (10a);
- inside the pressure screen (10b);
- after the pressure screen (10c).
The primary retention and drainage agent VERSINQUI can be formed by the following components:
- linear, branched or cross-linked polyacrylamides;
- starches;
- polyethylene oxides;
- dry strength and wet strength resins;
- organic and inorganic coagulants and - other polymers.
The before mentioned primary retention and drainage agent is preferably prepared in the client's plant. If the ingredi-ents are solid products, then the dissolution thereof is effec-tuated in an automatic powder dissolution unit, and if they are liquids, then it is effectuated by means of an on-line dosage pump. The dosage range of the primary retention agent lies be-tween 50 and 10.000 g/ton of paper.
ADDING STAGES
A) The first stage for adding the chemical products of the re-tention and drainage system called TOP DUAL according to the present invention is developed in the refined or non-refined stock tank (la) . This refined or non-refined stock is the re-sult of the disintegration of the fibrous material: rags of cellulose, waste paper and brokers, etc., produced in the so-called "helix" or "pulper" according to a production schedule.
This fibrous material converted in stock and after going through the depuration stages, screens, etc., arrives at the refined or non-refined stock tank (la).
At the suction of the stock pump (ib) of this refined or non-refined stock tank (la), as first adding point, a liquid chemical composition with retention and drainage properties ac-cording to the invention is added. This chemical composition corresponds to the product VERSINQUI A-250, secondary retention and drainage agent.
This stock with the agent VERSINQUI A-250 goes to the fan pump (9), pressure screen (10) and then to the head box (11).
There are nine other possible points of adding, mentioned be-fore, adequate for introducing the agent VERSINQUI A-250 to the paper stock to manufacture paper, paperboard, cardboard and similar products.
Adding the secondary agent VERSINQUI A-250, which is a liquid, pumpable product, manufactured in the plant of the sup-plier and which contains a smectite or a chemically modified version thereof, preferably a normal, activated or modified bentonite, is very easy, since it is preferably distributed in containers of 1.000 kg and a variable caudal pump is sufficient to adequately add this product. It is a simple installation: on a container, a second container is installed on a stand with the 1.000 kg of VERSINQUI A-250 product which is unloaded ac-cording to what the lower container consumes. Finally, during the course of the days, what is left inside the upper container is emptied and the container is changed. The lower container is connected to the dosage pump.
This first liquid composition, corresponding to the secon-dary retention and drainage agent called VERSINQUI A-250 has the following chemical formula:
General formula:
Water (from 5 to approx. 950 C): 0 - 92%, by weight;
Dispersing agent: 1 - 80%, by weight and Smectite (clay): 8 - 50% by weight.
Application example:
Warm water (40 - 60 C): 66.4%, by weight;
Sodium polyacrylate: 9.1% by weight and Smectite (clay): 24.5% by weight (preferably mont-morillonite).
The preparation of this first liquid composition of the secondary agent VERSINQUI A-250, prepared in the supplier's plant, allows for a de-lamination of the smectite (clay) and, therefore, the specific, superficial area of the smectite is strongly increased, with which an increase in the retention of fines, colloidal particles, semi-colloidal particles of the or-ganic and inorganic compounds present in the paper stock for the manufacturing of paper, paperboard, cardboard and other similar products, is achieved and this thus modified stock is flocculated by the second component, the so-called primary re-tention and drainage agent.
The pumpable liquid chemical composition of the secondary retention and drainage agent VERSINQUI A-250 according to the invention allows to concentrate the smectite clay 6.5% by weight in the watery dispersion, situation not one single sys-tem in use in the world currently achieves.
The dosage controlled via a pump with variable caudal of the VERSINQUI A-250 lies preferable between 150 and 1.000 g/ton of final produced paper. The dispersing agent of the before mentioned formula is preferably a sodium polyacrylate. However, it is also possible to formulate the product VERSINQUI A-250 with other dispersing agents different from sodium polyacry-late:
a) organic salts of alquil-aril-sulphonic acids;
b) purified sulpholignine;
c) extracts from seaweed;
d) condensed proteins and fatty acids;
e) sulphonate esters;
f) high molecular weight alquil sulphate sodium salts;
g) polycarboxilic compounds;
h) phosphates: hexametaphosphates, pyrophosphates, tripoly-phosphates, etc.;
i) sodium salt of polyaspartic acid;
j) alcohol;
k) acetone y 1) glycerin.
B) The second stage of the method according to the invention comprises adding the liquid composition or chemical product, called primary retention and drainage agent or VERSINQUI, which can be a:
- linear, branched or cross-linked polyacrylamide;
- starch;
- polyethylene oxide;
- dry strength and wet strength resin;
- organic and inorganic coagulant and - other polymer.
The adding points of the before mentioned primary retention agent can be between the positions la to 10c of the stream drawing of Figure 1. Adding the primary retention and drainage agent VERSINQUI is preferably done at the following points:
a) before the fan pump (9) ;
b) before the pressure screen (loa);
c) inside the pressure screen (lob) y a) after the pressure screen (10c).
The preparation and adding of the primary retention and drainage agent is preferably in the paper factory of the cli-ent. If the products are solid, then the dissolution is done in an automatic powder dissolution unit and if they are liquids, it is done by means of an on-line dilution dosing pump.
The dosage range of the primary retention and drainage agent lies between 50 and 10.000 g/ton final paper.
Contrarily to what is explained before, in the adding sys-tem described in the prior art, through the ORGANOPOL system of the company CIBA, the recommended adding points are the follow-ing:
a) adding ORGANOSORB, bentonite dispersion, at the level box (3) and b) adding ORGANOPOL, linear polyacrylamide, after the pres-sure screen (10c).
Generally, in the process of the present invention, the sequence of adding the two chemical compositions or the chemi-cal products can be done indistinctly; that is, first the sec-ondary retention and drainage agent and then the primary, or vice versa, first the primary retention and drainage agent and then the secondary. Additionally, in some cases the secondary retention and drainage agent can be used without the primary retention and drainage agent.
Here below the adding points of the TOP DUAL retention and drainage system according to the invention are summed up, re-ferring to Figure 1:
1)VERSINQUI A-250, secondary retention and drainage agent:
a) at the suction of the stock tank pump (1b);
b) at the level box (3);
c) at the suction of the stock pump feeding the stock depu-ration stage (4);
d) at other paper stock depuration stages (5);
e) to accepted of the first stage of stock depuration (6);
f) at the dilution water before the entry of the depurated stock (8) ;
g) before the fan pump (9) ;
h) before the pressure screen (loa);
i) inside the pressure screen (lob) and j) after the pressure screen (loc).
2)VERSINQUI, primary retention and drainage agent, between the stages of the process of manufacturing paper, paperboard, cardboard or other similar products from item la to 10c of Fig-ure 1, but preferably:
a) before the fan pump (9) ;
b) before the pressure screen (loa);
c) inside the pressure screen (lob) y d) after the pressure screen (10c).
Claims (19)
1. A process for the retention and drainage of a stock useful for the manufacturing of paper, paperboard, cardboard, cellulose and fiber cement, comprising the steps of (1) adding into paper stock from about 40 to about 2,000 grams of a secondary retention and drainage agent, per ton of produced paper, that retains fines, colloidal and semi-colloidal particles, and organic and inorganic compounds present in the stock, the secondary retention and drainage agent having a composition comprising a de-laminated smectite, and consisting essentially of, by weight:
(1) from about 1 to about 80% a dispersing agent selected from the group consisting of a polyacrylate, a purified sulpholignin, an extract of seaweed, a protein, a condensed fatty acid, a sulphonate ester, a high molecular weight alkyl sulphate, a polycarboxylic compound, a phosphate, a hexametaphosphate, pyrophosphate, and tripolyphosphate, a polyaspartic acid alkali salt, an alcohol, an acetone and other lower ketone, and glycerin, and mixtures thereof;
(2) from about 8 to about 50% de-laminated smectite; and (3) from 0 to about 91% water;
wherein the added secondary retention and drainage agent composition has a temperature in the range of from 5° to about 95° C; and optionally, (2) adding a primary retention and drainage agent that flocculates the stock, the primary retention and drainage agent, selected from the group consisting of a linear, branched, or cross-linked polyacrylamide, a starch, a polyethylene oxide, a wet strength resin, a dry strength resin, an organic or inorganic coagulant, and a polyvinyl amine.
(1) from about 1 to about 80% a dispersing agent selected from the group consisting of a polyacrylate, a purified sulpholignin, an extract of seaweed, a protein, a condensed fatty acid, a sulphonate ester, a high molecular weight alkyl sulphate, a polycarboxylic compound, a phosphate, a hexametaphosphate, pyrophosphate, and tripolyphosphate, a polyaspartic acid alkali salt, an alcohol, an acetone and other lower ketone, and glycerin, and mixtures thereof;
(2) from about 8 to about 50% de-laminated smectite; and (3) from 0 to about 91% water;
wherein the added secondary retention and drainage agent composition has a temperature in the range of from 5° to about 95° C; and optionally, (2) adding a primary retention and drainage agent that flocculates the stock, the primary retention and drainage agent, selected from the group consisting of a linear, branched, or cross-linked polyacrylamide, a starch, a polyethylene oxide, a wet strength resin, a dry strength resin, an organic or inorganic coagulant, and a polyvinyl amine.
2. The process according to claim 1 wherein the secondary retention and drainage agent can be added at a point in the process selected from: at the suction of a stock tank pump;
at a level box; at the suction of a stock pump feeding a stock depuration stage; at other paper stock depuration stages; at an outlet of a first stage of stock depuration; at a dilution water supply before entry of a depurated stock; before a fan pump; before a pressure screen; inside the pressure screen; and after the pressure screen.
at a level box; at the suction of a stock pump feeding a stock depuration stage; at other paper stock depuration stages; at an outlet of a first stage of stock depuration; at a dilution water supply before entry of a depurated stock; before a fan pump; before a pressure screen; inside the pressure screen; and after the pressure screen.
3. The process according to claim 1 wherein the primary retention and drainage agent can be added at a point in the process selected from before a fan pump, and before, inside and after a pressure screen of the paper machine.
4. The process according to claim 2 wherein the secondary retention and drainage agent is added in a continuous way.
5. The process according to claim 1 wherein the secondary retention and drainage agent is added at a level in a range between 150 and 1,000 g/ton produced paper.
6. The process according to claim 1 wherein the secondary retention and drainage agent is added to the stock in an acid, neutral or alkaline environment.
7. The process according to claim 1 wherein the smectite comprises a montmorillonite.
8. The process of claim 1 wherein the composition of the secondary retention and drainage agent comprises by weight: (1) about 9.1% a dispersing agent; (2) about 24.5%
smectite; and (3) about 66.4% water; and wherein the added composition has a temperature in the range of from about 40°C to about 60°C.
smectite; and (3) about 66.4% water; and wherein the added composition has a temperature in the range of from about 40°C to about 60°C.
9. The process of claim 1 wherein the process is performed in a paper plant, and wherein the secondary retention and drainage agent is provided as a composition prepared in a supplier's plant, and is brought to the paper plant for use.
10. The process of claim 1 wherein the smectite comprises a chemically modified smectite, a normal, activated or modified bentonite, and mixtures thereof.
11. The process according to claim 1 wherein the primary retention and drainage agent can be added in the process between a refined or non-refined stock tank, and exit of a pressure screen.
12. The process of claim 11 wherein the primary retention and drainage agent can be added continuously at a point in the process selected from: into a fan pump;
into entry of the pressure screen; into the interior of the pressure screen; and into the exit of the pressure screen.
into entry of the pressure screen; into the interior of the pressure screen; and into the exit of the pressure screen.
13. The process of claim 1 wherein the primary retention and drainage agent is added at a level in a range between 50 and 10,000 g/ton produced paper.
14. The process of claim 13 wherein the primary retention and drainage agent is added at a level in a range between 100 and 6,000 g/ton produced paper.
15. The process of claim 1, wherein the step of adding the primary retention and drainage agent precedes the step of adding the secondary retention and drainage agent.
16. The process of claim 1, comprising only the step of adding the secondary retention and drainage agent.
17. The process of claim 5 wherein the composition of the secondary retention and drainage agent comprises by weight: (1) about 9.1% a dispersing agent; (2) about 24.5%
smectite; and (3) about 66.4% water; the composition having a temperature in the range of from about 40°C to about 60° C.
smectite; and (3) about 66.4% water; the composition having a temperature in the range of from about 40°C to about 60° C.
18. The process of claim 17 wherein the secondary retention and drainage agent composition is added at suction of a stock pump feeding a stock depuration stage.
19. The process of claim 5 wherein the level of smectite in the secondary retention and drainage agent is about 24.5% by weight.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CL2003000904 | 2003-05-05 | ||
| CLCL904-2003 | 2003-05-05 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2466312A1 CA2466312A1 (en) | 2004-11-05 |
| CA2466312C true CA2466312C (en) | 2012-07-10 |
Family
ID=32968444
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2466312A Expired - Fee Related CA2466312C (en) | 2003-05-05 | 2004-05-04 | A retention and drainage system recommended for the manufacturing of paper, paperboard, cardboard and other similar products |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20040221977A1 (en) |
| EP (1) | EP1475476A1 (en) |
| JP (1) | JP2004332193A (en) |
| CN (1) | CN100532717C (en) |
| AR (1) | AR044156A1 (en) |
| BR (1) | BRPI0401695A (en) |
| CA (1) | CA2466312C (en) |
| HK (1) | HK1072085A1 (en) |
| MX (1) | MXPA04003942A (en) |
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| DE102004063005A1 (en) | 2004-12-22 | 2006-07-13 | Basf Ag | Process for the production of paper, cardboard and cardboard |
| JP4977127B2 (en) * | 2006-03-16 | 2012-07-18 | 住友精化株式会社 | Papermaking method and papermaking machine |
| US9752283B2 (en) | 2007-09-12 | 2017-09-05 | Ecolab Usa Inc. | Anionic preflocculation of fillers used in papermaking |
| CN103422395B (en) * | 2012-05-15 | 2016-03-02 | 纳尔科公司 | The method of dehydration, scraps of paper wet web strength and wet strength is strengthened in papermaking |
| US8088250B2 (en) | 2008-11-26 | 2012-01-03 | Nalco Company | Method of increasing filler content in papermaking |
| US8404083B2 (en) * | 2008-08-18 | 2013-03-26 | Basf Se | Process for increasing the dry strength of paper, board and cardboard |
| CN101634120B (en) * | 2009-08-25 | 2011-12-28 | 陕西科技大学 | Method for improving performance of paper stock in retention and drainage aiding |
| CN102242522B (en) * | 2010-04-07 | 2012-07-25 | 浙江凯丰纸业有限公司 | Device used for bidirectional combined papermaking enhancing process |
| FI124202B (en) * | 2012-02-22 | 2014-04-30 | Kemira Oyj | Process for improvement of recycled fiber material utilizing the manufacturing process of paper or paperboard |
| US9200408B2 (en) * | 2012-11-02 | 2015-12-01 | Ecolab Usa Inc. | Method of delivering a pigment dispersion and retention aid to a papermaking process |
| CN103850150A (en) * | 2014-03-27 | 2014-06-11 | 潍坊恒联美林生活用纸有限公司 | Manufacturing process of industrial dust-free wipe paper |
| CN107460770A (en) * | 2017-06-30 | 2017-12-12 | 安徽中亚纸业有限公司 | A kind of paper pulp environment-friendly paper pulp dehydrating agent |
| AU2019209164B2 (en) | 2018-01-16 | 2022-12-08 | Solenis Technologies, L.P. | Process for making paper with improved filler retention and opacity while maintaining wet tensile strength |
| CN109024041A (en) * | 2018-08-03 | 2018-12-18 | 广州市宏晓包装制品有限公司 | A kind of dewatering of pulp auxiliary agent |
| US10961662B1 (en) | 2019-12-23 | 2021-03-30 | Polymer Ventures, Inc. | Ash retention additive and methods of using the same |
| CN111979843A (en) * | 2020-08-24 | 2020-11-24 | 山鹰国际控股股份公司 | Wet-end papermaking process for improving surface smoothness of paper |
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| US150575A (en) * | 1874-05-05 | Improvement in rolling wire shutters | ||
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| US3052595A (en) * | 1955-05-11 | 1962-09-04 | Dow Chemical Co | Method for increasing filler retention in paper |
| EP0017353B2 (en) * | 1979-03-28 | 1992-04-29 | Ciba Specialty Chemicals Water Treatments Limited | Production of paper and paper board |
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| SE451739B (en) * | 1985-04-03 | 1987-10-26 | Eka Nobel Ab | PAPER MANUFACTURING PROCEDURE AND PAPER PRODUCT WHICH DRAINAGE AND RETENTION-IMPROVING CHEMICALS USED COTTONIC POLYACRYLAMIDE AND SPECIAL INORGANIC COLLOID |
| GB8602121D0 (en) * | 1986-01-29 | 1986-03-05 | Allied Colloids Ltd | Paper & paper board |
| US4964955A (en) * | 1988-12-21 | 1990-10-23 | Cyprus Mines Corporation | Method of reducing pitch in pulping and papermaking operations |
| JPH0247394A (en) * | 1988-08-05 | 1990-02-16 | Mizusawa Ind Chem Ltd | Additive for paper making |
| GB8828899D0 (en) * | 1988-12-10 | 1989-01-18 | Laporte Industries Ltd | Paper & paperboard |
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| TW550325B (en) * | 1999-11-08 | 2003-09-01 | Ciba Spec Chem Water Treat Ltd | Manufacture of paper and paperboard |
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-
2004
- 2004-04-26 MX MXPA04003942A patent/MXPA04003942A/en active IP Right Grant
- 2004-04-29 CN CNB2004100550313A patent/CN100532717C/en not_active Expired - Fee Related
- 2004-05-03 AR ARP040101499A patent/AR044156A1/en active IP Right Grant
- 2004-05-03 EP EP20040076330 patent/EP1475476A1/en not_active Withdrawn
- 2004-05-04 CA CA2466312A patent/CA2466312C/en not_active Expired - Fee Related
- 2004-05-05 US US10/709,443 patent/US20040221977A1/en not_active Abandoned
- 2004-05-05 BR BR0401695-5A patent/BRPI0401695A/en not_active IP Right Cessation
- 2004-05-06 JP JP2004137822A patent/JP2004332193A/en active Pending
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2005
- 2005-06-08 HK HK05104811.4A patent/HK1072085A1/en not_active IP Right Cessation
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|---|---|
| HK1072085A1 (en) | 2005-08-12 |
| MXPA04003942A (en) | 2007-06-29 |
| CA2466312A1 (en) | 2004-11-05 |
| BRPI0401695A (en) | 2005-01-18 |
| CN1576460A (en) | 2005-02-09 |
| JP2004332193A (en) | 2004-11-25 |
| CN100532717C (en) | 2009-08-26 |
| US20040221977A1 (en) | 2004-11-11 |
| AR044156A1 (en) | 2005-08-24 |
| EP1475476A1 (en) | 2004-11-10 |
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