KR20160021851A - A method of improving dewatering efficiency, increasing sheet wet web strength, increasing sheet wet stregnth and enhancing filler retention in papermaking - Google Patents

Abstract

The present invention provides a method for improving dewatering efficiency in a papermaking process, increasing sheet wet web strength, increasing sheet wet strength, and enhancing filler retention. The method improves the efficiency of the drainage aid or wet web strength aid or wet strength aid by coating at least a portion of the filler particles with a material that prevents the filler material from adhering to such additives. The drainage additive or wet web strength additive or wet strength adjuvant firmly holds the cellulose fibers together and is not wasted on the filler particles.

Description

FIELD OF THE INVENTION The present invention relates to a method of improving dewatering efficiency upon papermaking, increasing sheet wet web strength, increasing sheet wet strength, and improving filler retention. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] FILLER RETENTION IN PAPERMAKING}

BACKGROUND OF THE INVENTION

The present invention relates to a method of improving dewatering efficiency in a papermaking process, increasing sheet wet web strength, increasing sheet wet strength, and enhancing filler retention. Typically, in the papermaking process, chemicals are added to the wet end to aid in the dehydration, retention and wetting of the slurry or the improvement of the dry sheet strength. The wet part of the papermaking process refers to the stage in the papermaking process in which the fibers are dispersed in the form of slurries in water. The fiber-water slurry then proceeds to a drainage and dehydration process to form a wet web. The solids content after this wet forming process is about 50%. The wet web is further dried and forms a dry sheet of paper mat. Paper mats include water and solids, typically 4 to 8% water. The solid portion of the paper mat comprises fibers (typically, cellulose-based fibers) and may also include fillers.

Fillers are mineral particles added to the paper mat during the papermaking process to improve the opacity and light reflection properties of the resulting paper. Some examples of fillers are described in U.S. Patent No. 7,211,608. Fillers include inorganic and organic particles or pigments used to increase opacity or brightness, reduce porosity, or reduce the cost of paper or cardboard sheets. Some examples of fillers include at least one of kaolin clay, talc, titanium dioxide, alumina trihydrate, barium sulfate, magnesium hydroxide, pigments such as calcium carbonate, and the like.

Calcium carbonate fillers consist of two forms: GCC (ground calcium carbonate) and PCC (precipitated calcium carbonate). GCC is natural calcium carbonate rock and PCC is synthetically produced calcium carbonate. Since this has a larger specific surface area, PCC has greater light scattering ability and provides better optical properties to the resulting paper. However, for the same reasons, PCC-filled paper mats produce paper that is weaker than GCC-filled paper at dry strength, wet strength and wet web strength.

The filler is generally much smaller than the fibers, so that the filler has a much larger specific surface area than the fibers. One of the problems found by those skilled in the art to increase the filler content in the sheet is that the high filler content reduces the efficiency of wetting chemicals such as dehydrating auxiliaries, wet web strength adjuvants and wet strength adjuvants. The present invention is to provide a novel filler pretreatment to reduce the adsorption of wetting chemicals onto the filler surface and thereby increase the efficiency of wetting chemicals such as dehydrating auxiliaries, wetting web strength aids and wet strength aids.

Paper wet web strength is very important for paper manufacturers because increased paper wet web strength will increase machine runnability and reduce sheet breakage and machine downtime. Paper wet web strength depends on the number and strength of bonds formed between the woven fibers of the paper mat. Filler particles having a larger surface area are likely to engage these fibers and are more likely to interfere with the number and strength of such bonds. Due to its larger surface area, PCC fillers are more detrimental to such bonding than GCC.

Paper dewatering efficiency is also of great importance to paper producers because the reduced dewatering efficiency in wetted areas increases the steam demand for drying operations and reduces machine speed and production efficiency. Dehydrating auxiliaries are widely used to improve the dewatering efficiency to reduce energy consumption and increase machine speed and production efficiency.

A brief summary of the invention

In order to satisfy the long-felt but unresolved need identified above, at least one embodiment of the present invention is a papermaking process comprising a filler,

Providing a blend of filler particles, at least one drainage additive or wet web strength additive or wet strength aid, and a cellulose fiber stock, step,

Treating the filler particles with the composition in the absence of a cellulose fiber stock solution,

Combining the filler particles with the cellulose fiber mother liquor,

Treating the blend with at least one wet strength additive or wet web strength additive or drain additive,

Forming a paper mat from the formulation; and

And delivering the composition to a distribution head for mixing into a filler slurry,

At least 10% of the filler particles are precipitated calcium carbonate, at least 10% of the filler particles are heavy calcium carbonate, the cellulose fiber stock solution comprises a plurality of cellulose fibers and water, the composition comprises a wet strength additive or wet web strength Improves the performance of additives or drainage additives,

At least a portion of the composition is added to the filler with a spin mixing device having a dispensing head, the spin mixing device is rotated by a drive, arranged in a container containing a slurry of filler particles, associated with a spinning surface, The head has a dispensing outlet along which the composition is provided with a slurry and a mixing blade,

Characterized in that the dispensing outlet is formed as an opening and the mixing blade is formed as a strip extending transversely to the plane of rotation and having a length equal to at least half of the inner diameter of the slurry pipe.

Additional features and advantages are described herein and will become apparent from the following detailed description.

The detailed description of the invention is set forth with particular reference to the following drawings:
1 is a cross-sectional view of a device used to supply the invention to a slurry of filler particles.
Figure 2 is an exploded view of a cross-sectional view of a device used to supply the invention to a slurry of filler particles.
In the present description, like reference numerals in the drawings will indicate similar features, unless otherwise specified. The drawings are merely illustrative of the principles of the invention and are not intended to limit the invention to the specific embodiments illustrated.

DETAILED DESCRIPTION OF THE INVENTION

In at least one embodiment of the present invention, the present invention is a papermaking process comprising a filler. In at least one embodiment of the invention, the papermaking process comprises producing a filler blend of PCC and GCC, wherein the PCC comprises at least 10% by weight filler, the GCC comprises at least 10% filler mass, Pretreating at least a portion of the filler particles with a wet web strength additive or a wetting strength adjuvant or a coating that reduces the adhesion between the wet strength adjuvant and the filler particles, the filler blend and the wet web strength additive or the drainage aid or the wet strength aid, To the mat.

Adding a wet web strength additive or drainage aid or wet strength adjuvant to a paper mat can increase the wet web strength of the paper being formed, improve drainage, improve machine speed and running ability, or improve sheet wet strength It has been known for a long time. Some examples of wet strength additives, wet web strength additives and drainage aids are described in U.S. Patent Nos. 7,125,469, 7,615,135, and 7,641,776.

Unfortunately, it is not practical to add large amounts of wet strength adjuvant or wet web strength additive or drain adjuvant to compensate for the drawbacks of large amounts of filler in the paper mat. One reason is that such additives are expensive, and that a large amount of additives will result in commercially impractical production costs. In addition, the addition of too much additive adversely affects the papermaking process and hinders the operability of various types of paper making equipment. In addition, the cellulose fibers may only adsorb a limited amount of wet strength adjuvant or wet web strength additive or drain adjuvant. This imposes limits on how many adjuvants can be used. One reason for why this is so is that wet strength or wet web strength additives or drain adjuvants tend to neutralize the anionic fiber / filler charge, and when these charges are neutralized, further adsorption of such additives is inhibited to be.

In addition, adding filler to the paper mat also reduces the efficiency of the wet strength adjuvant or wet web strength additive or drain adjuvant. Such additives tend to coat the filler particles. The more filler particles are present, the less wetting strength adjuvant or wetting web strength additive or drainage agent that can be used to coat the filler particles with the additive and thus bond the cellulose fibers together. Because of the maximum amount of wet strength additive or wet web strength additive or drainage agent that can be added, more filler always means less effective strength additive. This effect is more pronounced with PCC than with GCC because the higher surface area of PCC is coated with more additive than GCC.

In at least one embodiment of the present invention, at least a portion of the filler particles are pretreated with the composition to prevent, at least in part, adhesion of the wet strength additive or wet web strength additive or drain adjuvant to the filler particles. Pretreatment allows for the complete coating of some or all of one or more filler particles with the composition. Alternatively, pretreatment may be considered to apply the composition to only a portion of one or more filler particles, to fully coat some filler particles, and to apply the composition to only a portion of some other particle. In at least one embodiment, the pretreatment is performed with at least a portion of the composition described in U.S. Patent No. 5,221,435, particularly the cationic charge-deflecting species described in the patent. In at least one embodiment, the pretreatment is performed with the diallyl-N, N-disubstituted ammonium halide-acrylamide copolymer described in U.S. Patent No. 6,592,718.

Although pre-treatment of filler particles is known in the art, conventional pretreatment methods for filler particles are not concerned with the effect of wet strength additives or wet web strength additives or drainage aids on adhesion to filler particles. In fact, many prior art pretreatments increase the adhesion of strength additives to filler particles. For example, U.S. Patent No. 7,211,608 describes a method of pretreating filler particles with a hydrophobic polymer. However, this pretreatment is not associated with adhesion between the strength additive and the filler particles, but only splashes water to offset excess water absorbed by the strength additive. In contrast, the present invention reduces the interaction between the wet strength additive or the wet web strength additive or drain adjuvant and the filler particles and, unexpectedly, significantly increases paper strength, sheet dewatering and machine running capability.

When comparing the wet tensile strength of the presented paper to the percent filler in relation to the total solids fraction of the paper mat used to produce the paper presented, the results clearly show that the sheet is not wetted with the wet strength adjuvant 63700 (temporary wet strength adjuvant) It has a very weak wet strength. Velox could significantly increase sheet wet strength. The pretreatment of the filler alone did not increase the sheet wet strength. However, the filler pretreatment further promoted the Velox performance, which resulted in higher sheet wet strength.

When comparing the wet web tensile strength of a proposed paper against the percent filler with respect to the total solids fraction of the paper mat used to produce the paper presented, the relationship between increasing filler content and decreasing paper wet web strength is a linear relationship . Without adding Nalco dehydrating auxiliaries (wet web strength aid) 63700, the paper sheet has a very poor wet web strength. Sheet wet web strength can be significantly improved by using Nalco dehydration aid 63700. [ Pretreatment with filler alone negatively affects paper wet web strength. However, the filler pretreatment can further elongate the performance of the Nalco dehydration aid 63700 and an additional 20% wet strength improvement is achieved by a filler pretreatment at a lower ash content. For higher ash content, the performance of 63700 was much higher than 20%. This is because the reduction of the efficiency of the captured strength additive to the filler particles was relieved by the filler pretreatment.

At least some of the fillers included by the present invention are well known and commercially available. These include any inorganic or organic particles or pigments used to increase opacity or brightness, reduce porosity, or reduce the cost of paper or cardboard sheets. The most common fillers are calcium carbonate and clay. However, talc, titanium dioxide, alumina trihydrate, barium sulfate, and magnesium hydroxide are also suitable fillers. Calcium carbonate includes heavy calcium carbonate (GCC) in the form of a dried or dispersed slurry, chalk, precipitated calcium carbonate (PCC) of any morphology, and precipitated calcium carbonate in dispersed slurry form. GCC or PCC in dispersed slurry form is typically formed using a polyacrylic acid polymer dispersant or a sodium polyphosphate dispersant. Each of these dispersants imparts significant anionic charge to the calcium carbonate particles. The kaolin clay slurry is also dispersed using a polyacrylic acid polymer or sodium polyphosphate.

In at least one embodiment, the treating composition is any one of the compositions described in U.S. Patent No. 6,592,718 or a combination thereof. In particular, any of the AcAm / DADMAC copolymer compositions described in detail above is suitable as a treatment composition. An example of an AcAm / DADMAC copolymer composition is product # Nalco-4690 (hereinafter referred to as 4690) from Nalco Company (Naperville, Illinois).

The treating composition may be a coagulant. Coagulants included in the present invention are well known and commercially available. These may be inorganic or organic. Representative inorganic coagulants include alum, sodium aluminate, polyaluminium chloride or PAC (also known as aluminum chlorohydroxide, aluminum hydroxide chloride, and polyaluminum hydroxychloride), sulfated polyaluminium chloride, Polyaluminum silicasulfate, ferric sulfate, ferric chloride, and the like, and blends thereof.

Some organic coagulants suitable as a treating composition are formed by condensation polymerization. Examples of polymers of this type include epichlorohydrin-dimethylamine (EPI-DMA), and EPI-DMA ammonia crosslinked polymers.

Further coagulants suitable as treating compositions are the polymers of ethylene dichloride and of ammonia, or of ethylene dichloride and of dimethylamine with or without ammonia, multifunctional amines such as diethylenetriamine, tetra Ethylenepentamine, hexamethylenediamine, and the like, and condensation polymers of polymers such as melamine formaldehyde resins.

Additional coagulants suitable as treatment compositions include cationically charged vinylated polymers such as (meth) acrylamide, diallyl-N, N-disubstituted ammonium halides, dimethylaminoethyl methacrylate and its quaternary ammonium salts, dimethylaminoethyl Acrylate and its quaternary ammonium salt, methacrylamidopropyltrimethylammonium chloride, diallylmethyl (beta-propionamido) ammonium chloride, (beta-methacryloyloxyethyl) trimethylammonium methylsulfate, quaternized poly Copolymers, and terpolymers of acrylamide or methacrylamide that produce vinylamides, vinyllactams, vinylamines, and, in reaction, Mannich or quaternary Mannich derivatives. A preferred quaternary ammonium salt may be produced using methyl chloride, dimethyl sulfate, or benzyl chloride. The terpolymer may comprise anionic monomers such as acrylic acid or 2-acrylamido 2-methylpropanesulfonic acid, where the total charge for the polymer is cationic. The molecular weight of these polymers, i.e., both vinyl addition and condensation polymers, is as low as several hundreds or as high as several million. Preferably, the molecular weight range should be from about 20,000 to about 1,000,000. In at least one embodiment, the pretreatment is carried out by any, some, or all combinations of any of the compositions described as a composition suitable for pretreating filler particles.

In at least one embodiment, the wet strength adjuvant or wet web strength additive or dehydrating adjuvant has the same charge as a composition suitable for treating the filler particles. When the two have the same charge, the filler additive is less likely to adsorb the wet strength adjuvant, the wet web strength additive, or the drain adjuvant on its surface. The wet strength adjuvant, wet web strength additive or drain adjuvant included by the present invention may be any of the materials described in U.S. Patent No. 4,605,702 and U.S. Patent Application No. 2005/0161181 Al, Glycoxylated acrylamide / DADMAC copolymer compositions. An example of a glycoxylated acrylamide / DADMAC copolymer composition is Product # Nalco 63700, manufactured by Nalco Company (Naperville, Illinois). Another example is an amine-containing polymer comprising an allylamine / acrylamide copolymer and a polyvinylamine, and one example is polyamide-polyamine-epichlorohydrin (PAE).

In at least one embodiment, the fillers used are PCC, GCC, and / or kaolin clay. In at least one embodiment, the fillers used are PCC, GCC, and / or kaolin clay with polyacrylic acid polymer dispersants or blends thereof. The ratio of the wet strength additive to the solids paper mat or the wet web strength additive or the drain additive may be 3 kg of additive per ton of paper mat.

In at least one embodiment, at least a portion of the filler particles are pretreated using a rotary mixing apparatus. The spin mixing apparatus includes a dispensing head configured and arranged to rotate as it dispenses a treatment chemical to the filler particles. In at least one embodiment, the spin mixing device is the device described in U.S. Patent No. 5,993,670. The apparatus can be blended into the flocculant liquid (s) process stream, wherein a dispensing head rotated by the drive is arranged in the pipe / conduit through which the slurry of filler particles flows and is associated with the rotating surface, The dispensing head has a coagulant outlet distributed along its circumference and a mixing blade and is connected to the flocculant liquid delivery conduit.

In at least one embodiment, the invention is also directed to an apparatus for mixing a flocculant liquid formed by a mixture of an activator and water, the flocculant liquid being added to 100 parts of the filler slurry, wherein the flocculant liquid contains the required amount of active agent To 100 parts of the slurry.

There are cases where the device for mixing is located in the direction of the slurry flow, downstream of the transfer pump or centrifuge, and that the liquid and filler mix well with each other. However, there are certainly a number of cases where this is not the case and the mixing apparatus has failed to perform a satisfactory mixing of the flocculant liquid and the filler. In the known device of the type mentioned above (DE-05 40 29 824), the flocculant outlet is formed as a hole or nozzle, each of which is formed as a journal-like projection, The dimensions of the mixing blade and the outlet are very small compared to the width of the filler slurry stream. In some cases, the mixing of the flocculant liquid with the slurry obtained with this apparatus is insufficient. That is, the added flocculant liquid is not sufficiently uniformly distributed in the slurry stream behind the device and is not contained in the slurry in an amount required for satisfactory agglomeration.

It is therefore an object of the present invention to provide a device of the type described above in which a better mixing of the flocculant liquid against the slurry is achieved. An apparatus according to the invention for achieving this object is characterized in that the flocculant outlet is formed as a slot and the mixing blade is formed as a strip extending transversely to the plane of rotation and having a length corresponding to at least half of the slurry stream width .

In at least one embodiment, only one, some, or all of the chemicals added to the pretreatment process are added by the rotating device.

In at least one embodiment, the configuration of the dispensing head of the apparatus results in improved mixing and dispensing of the flocculant liquid in the slurry. The flocculant liquid emerges from each slot in the form of a wide strip, into which the next mixing blade is inserted in the opposite direction of rotation and the aggregate liquid along its edge is drawn through the slurry as a foggy strip . The flocculant liquid is delivered to the slurry as intermittent torrents through the slots, and the slots and strips are arranged in turn in the direction of rotation. The dimensioning of the length of the slots and blades depends on the diameter of the stream or dispensing head.

In at least one embodiment, the coagulant slots and the strip-shaped blades may extend both in the direction of the slurry stream and substantially perpendicular to the slurry stream. Another embodiment of the present invention is possible in which the rotational axis of the mixing head extends at an angle to the slurry stream. However, the rotating surface of the mixing head generally extends substantially in the direction of the slurry stream.

Each slot is formed of two or more slot sections arranged in succession, for example. However, it is particularly advantageous and advantageous that each slot is continuous along its entire length. This prevents clogging and unwanted high rate of flocculation of the flocculant liquid.

Each strip-shaped mixing blade is divided, for example, by a radial incision in a comb-like fashion along its length. However, it is particularly advantageous and advantageous if each strip-shaped mixing blade is continuous over its length. This improves the rigidity of the strip-shaped mixing blades and improves the mixing action.

The cross-section of each exit slot may vary along its length to control the amount of coagulant liquid that exits. It is particularly effective and advantageous when the cross-sectional area of each exit slot is increased toward the middle as viewed along its length. This shape of the outlet slot is used in the middle of the slurry pipe where the slot extends transversely with respect to the stream direction as more slurry is from the side. Due to the uniform slot width, a uniform delivery of the flocculant to the slurry is achieved.

In at least one embodiment, the slot forming the outlet for the flocculant liquid has a width of, for example, 7 to 9 mm. The larger the amount of coagulant liquid that must be delivered in time units, the wider the slot, the smaller the amount of coagulant liquid that must be delivered in time units, the narrower the slot.

It is particularly effective and advantageous when the edges of each strip-shaped mixing blade extend approximately parallel to the inner contour of the slurry pipe to form a gap therebetween. The elongated strip-shaped mixing blade extending in the radial direction improves the mixing action. However, there must be a gap between the mixing blade and the slurry conduit, and the gap is large enough to allow passage of the stone pieces present in the slurry.

This clearance is particularly important when the strip-shaped mixing blade extends transversely to the stream and is large. If the strip-shaped mixing blade extends transversely to the stream, the clearance is preferably smaller in the direction of the axis of rotation than in the transverse direction relative to the axis of rotation.

A particularly advantageous and advantageous embodiment of the invention is obtained when the direction of rotation of the dispensing head drive can be varied. In the apparatus according to the invention, the mixing blades are relatively large or protruded relative to the slurry pipe cross section, so that when the dispensing head rotates in the same direction for a long time, clogging into hard slices and fiber or thread accumulation There is a risk. Rotation in the opposite direction prevents this clogging and accumulation.

One, two, and / or more flocculant outlets may be provided, for example, between two mixing blades. However, it is particularly advantageous and advantageous that the outlet slots and the strip-shaped mixing blades alternate in the rotational direction. This also improves the mixing process. Two or more outlet slots and two or more strip-shaped mixing blades are provided on the dispensing head in the rotational direction.

It is furthermore particularly effective and advantageous if the inner cross section of the slurry pipe in the region of the dispensing head is similar to the further inner cross section of the slurry pipe. Thus, the apparatus according to the invention eliminates the reduction of the slurry pipe and the associated increase in flow rate of the slurry. The dispensing head results in a larger reduction in cross-section that is previously available for the slurry.

It is particularly effective and advantageous when the dispensing head is formed as a cylindrical tubular section and / or when the outer diameter of the dispensing head corresponds to at least 0.4 of the slurry pipe inner diameter. This simplifies the configuration of the dispensing head and improves the stiffness, while the shape of the strip-shaped mixing blades and exit slots provides an increased demand for stiffness of the dispensing head.

A particularly advantageous and advantageous embodiment of the invention is that the dispensing head passes through a rotatably supported connecting tube extending further from the slurry pipe and connected to the drive and to the flocculating liquid delivery conduit, Is formed when the flocculant liquid delivery conduit is rotatably supported in the open connection chamber. This manner of delivery of the flocculant liquid to the rotatable dispensing head ensures the increased rigidity of the connector and the support of the connector by simple means. This is made possible by the device according to the invention due to the "stone grinding" cooperation of the strip-shaped mixing blades and slurry pipes.

For satisfactory delivery of the flocculant liquid (s) through the exit slot, the flow cross-section available for the flocculant liquid (s) is very important. In one embodiment of the invention, all of the exit slots together have a smaller cross-section than the proceeding flow cross-section of the flocculant liquid. The entire cross-section of the inlet opening is not smaller than the flow cross-section in the delivery conduit and the connecting pipe. The flow cross-section at the dispensing head and the flow cross-section at the connector are similar. The arrangement of the connecting tubes in the sealed connection chamber can optimize the flow cross-section of the flocculant liquid.

It is particularly effective that the slurry can penetrate into the outlet slot if the flocculant liquid is not under pressure, for example, when the flocculant liquid pump is not working, if the check valve is arranged in the flocculant liquid delivery conduit, Do. The sealing and bearing in the connecting chamber remain lubricated with the flocculant liquid when the flocculant liquid from the flocculant liquid pump is no longer under pressure.

A particular advantageous and advantageous embodiment of the invention is obtained when the dispensing head is driven at a rotational speed of 700 to 2,500 revolutions per minute, preferably 1,000 to 2,000 revolutions per minute. At such relatively high rotational speeds, the desired improved mixing and dispensing of the flocculant liquid in the slurry occurs. At excessively low rotational speeds below 500 rev / min, the strip or stream of flocculant liquid is discontinued. However, large speeds require too high a cost to achieve the desired effect. In the known device of the type described above (DE-05 4029824), flocculants stored in the reservoir can be used. It is further known (DE-05 39 01 292) to add fresh water to the flocculent available in liquid or powder form to obtain about 1% of the flocculant mother liquor. The coagulant mother liquor is then mixed with 4 to 10 parts of make-up water in a filling station to obtain a flocculant in the form of a so-called commercial solution. This flocculant is added to the slurry in an amount of 18-20% of the amount of filler slurry. That is, about 20 parts of the flocculant liquid is added to 100 parts of the filler particles in the form of a flocculant formulation. At this time, the coagulant-containing slurry, i.e., the conditioned filler, contains the liquid 1/6 added by the addition of the coagulant liquid to be added additionally.

In known applications, a large amount of water is used for further processing of the coagulant formulation, which is costly. For processing, in addition to a device for obtaining a mother liquor, a device for obtaining a commercial solution is required, which incurs additional costs associated with the device and additional costs associated with driving the device. The coagulant and its water are delivered until they are mixed with the slurry, and the transfer requires energy, which is costly. The water component of the flocculant is passed along with the slurry to a filter press, passed through a filter press and refined to the end. Thus, in known applications, the increased additional cost is associated with the water contained in the flocculant liquid.

Therefore, it is an object of the present invention to improve the process as described above so that the costs associated with the use of the flocculant liquid or its water content increase are eliminated. This object is achieved according to the invention by designing such a device according to the invention so that up to 3t of flocculant liquid should be provided for a filler slurry of 100t.

It has been found that the use of the dispensing head of the device according to the invention allows to remove the water component of the flocculant liquid without excluding the efficiency of the flocculant liquid mixed in the slurry. In known applications, a large amount of water component is required to achieve the desired effect with a certain amount of additive, but this is not necessary when the apparatus of the present invention is used. The water component of the flocculant liquid can be greatly reduced, thereby correspondingly eliminating the costs associated with this water content. Less water requires less water to be pumped and less water to purify.

The improved efficiency achieved by the present invention can be described as follows without claiming to be correct: the particular shape of the mixing blade of the apparatus of the present invention greatly degrades the filler slurry particles of the slurry, The disassembled pieces become open fissures. The specific shape of the flocculant outlet ensures that the flocculant liquid takes on the shape of a large surface membrane that covers the newly open openings, thereby ensuring that the filler and flocculant mixture is intensified. It is not necessary to further dilute the additive with a large amount of water by mixing the flocculant liquid according to the present invention in a finely distributed state so as to increase the flocculant liquid water content. Thus, according to certain advantageous and advantageous embodiments of the present invention, the flocculant liquid is used as the mother liquor, and the additives are mixed with the water in a single step. With this embodiment, additional stations for further mixing with water are eliminated.

Referring now to Figures 1 and 2, in at least one embodiment, the apparatus is mounted on a filler slurry delivery conduit / pipe 1 and the filler slurry passes through the filler slurry delivery conduit / Lt; / RTI > The device can be mounted on the slurry pipe 1 by means of an elongated flange 3 and comprises a connecting chamber 4 projecting from the flange 3. From the connecting chamber 4 a dispensing head 6 extends to the slurry pipe 1 and is rotated by a drive 7 provided at the opposite end of the chamber 4 and formed as an electric motor. The flocculant liquid conduit 8 is opened into the chamber 4 and the check valve 9 is located in the conduit 8. The dispensing head 6 forms an outlet slot 10 and has a strip-shaped mixing blade 11.

The sleeve 14 supports the connecting tube 15 at the shaft extension 12 extending from the drive 7 and at the end wall of the connecting chamber 4 and is provided with an axial face seal 16 Through which the shaft extension 13 extends. The connector tube 15 has a plurality of elongated inlet openings 17 through which the coagulant flows from the connecting chamber to the connector tube. The connecting tube 15 protrudes into the connecting chamber 4 through which a sleeve 5 with a flat surface is provided in the flange 3 and the tubular dispensing head 6 forms an integral part of the connecting tube 15 do. The dispensing head 6 is associated with a rotating surface 18 indicated by the dashed line. Each mixing blade 11 forms an arcuate edge 19 which limits the slot 20 with respect to the slurry pipe 1 having a circular cross section at the corresponding blade position.

The foregoing description is better understood with reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of the invention.

Example  One

1 (i) Pretreatment of filler:

A blend of filler particles was obtained from a paper mill. The blend filler was a mixture of 50% PCC and 50% 100% GCC. The filler blend was diluted with tap water to a 20% solids content. 200 mL of the diluted filler blend was placed in a 500 mL glass beaker. Stirring was carried out for at least 30 seconds before adding the coagulant. The stirrer was a R1342, 50 mm, EUROSTAR digital overhead mixer (both from IKA Works, Inc., Wilmington, North Carolina) with a 4-blade propeller. The coagulant solution was slowly added with stirring at 800 rpm and after the initial 30 seconds of mixing. The coagulant solution used was 4690. The dose of coagulant was 1 kg / ton based on the weight of the dried filler. Stirring was continued at 800 rpm until all of the coagulant was added. Thereafter, the stirring speed was increased to 1500 rpm for 1 minute.

1 (ii) Filler Usage:

The feedstock was prepared by disintegrating a commercial bleached hardwood dry lap. A mixture of 50% PCC and 50% GCC was added to the pulp stock to achieve different filler content in the sheet. 200 ppm Nalco 61067 was used as a retention aid. For the pretreatment evaluation, the filler mixture was pretreated with Nalco coagulant 4690 before the filler was added to the stock. During hand sheet manufacture, 3 kg / ton Nalco 63700 was added to improve sheet wet web strength. The inventors sought to evaluate the effect of the filler pretreatment on the crimp dewatering performance of 63700 by measuring the sheet wet web strength. The handsheet was compressed to a specified solids content (50%) by controlling the same pressure level at 60 占 폚 and the time required to completely decompose the wetted sheet under water under a shear force of 1000 RPM was measured using a sheet And recorded for comparison with wet web strength. The results showed that the sheet wet web strength could be significantly improved by the addition of 63,700. Filler pretreatment could additionally enhance sheet wet web strength by an additional 20% at an even lower ash content. For higher ash content, the 63700 performance was much higher than 20%.

Example 2

A machine test was performed, in which the paper machine manufactured GAB300 at a machine speed of 900 m / min. Cellulose fibers 14% MXW; 3% coated broke; 17% SOW; 12% uncoated Broke, 44% DIP and 10% ONP. In addition, the feedstock contained GCC. During the test, all wetting additives, including 15 / ton Nalco squeeze dehydration aid 63700, retention aid, sizing agent, and cationic starch, were kept constant.

1) Enhancement of filler retention:

4690 was gradually increased from 0.5 kg / ton to 2 kg / ton based on the filler. The online ash content was gradually increased by adding 4690 to the filler pipe. Obviously, pre-treatment of the filler increased the score by 0.7 points from 15.6% to 16.3%. Typically, for the same grade production, the recorded ash content of DCS was about 12% without using Nalco 63700. It should be noted that the improvement in ash content is due to the only filler ply. Therefore, the increase in ash content in the filler ply is estimated to be about 1.4% as the filler ply accounts for half the basis weight of the final product. FPAR increased from 70% to 75%, which could explain why the final ash content was significantly increased.

2) Reduced vapor pressure:

Also, the vapor pressure of the pre-dryer was found to be reduced through pretreatment of the filler. The vapor pressure was gradually reduced from 2.15 bar to 2 bar from 10:30 am to 2:00 pm. The vapor pressure returned to only 2.05, although the press presses of the first press section and the press section of the second press section were reduced from 550 to 470 and 600 to 580, respectively.

During the test, after about 1 hour of pretreatment of the filler, the ash content increased from approximately 15.6% to 16.3% and then remained at the same level for several hours. On the other hand, the vapor pressure kept decreasing for several hours until the press load was reduced. This appears to indicate that the steam reduction is not only due to the ash content increase. In addition, the reduction in steam requirement of this test should be due to the lowering of total steam loss by ash alone, as the 4690 is only due to such ply, since it was applied to the filler ply only. Therefore, the results showed that the filler pretreatment could enhance the 63700 performance as a squeeze dehydrating agent or a wet web strength aid.

Those skilled in the art will appreciate that all of the methods described above may also be applied to paper mats comprising other non-cellulosic fibrous materials, paper mats comprising a mixture of cellulosic fibrous materials and non-cellulosic fibrous materials, and / ≪ RTI ID = 0.0 > and / or < / RTI >

Changes may be made in the structure, operation, and arrangement of the method of the invention described herein without departing from the concept and scope of the invention as defined in the claims. Although the present invention may be embodied in many different forms, certain preferred embodiments of the invention are described herein. The present disclosure is illustrative of the principles of the present invention and is not intended to limit the invention to the specific embodiments illustrated. The present invention also includes any possible combinations of some or all of the various embodiments described herein. All patents, patent applications, and other citations referred to in this application, or any cited patent, cited patent or other citation, are incorporated herein by reference in their entirety. In addition, the present invention contemplates embodiments that exclude any, some, or all of the compositions, methods, ingredients, elements, or other parts of any citation.

The above description is intended to be illustrative and not non-exclusive. This description will suggest many variations and alternatives to those skilled in the art. All such alternatives and modifications are intended to be included within the scope of the claims, and the term " comprising " means "including, but not limited to. Those skilled in the art will recognize that other equivalents to the specific embodiments described herein are intended to be covered by equivalents as well.

This completes the description of preferred and alternative embodiments of the invention. Those skilled in the art will recognize that other equivalents to the specific embodiments described herein are intended to be encompassed by the appended claims.

Claims (19)

A papermaking process comprising a filler,
Providing a blend of filler particles, at least one drainage additive or wet web strength additive or wet strength aid, and a cellulose fiber stock, step,
Treating the filler particles with the composition in the absence of a cellulose fiber stock solution,
Combining the filler particles with the cellulose fiber mother liquor,
Treating the blend with at least one wet strength additive or wet web strength additive or drain additive,
Forming a paper mat from the formulation; and
And delivering the composition to a distribution head for mixing into a filler slurry,
At least 10% of the filler particles are precipitated calcium carbonate, at least 10% of the filler particles are heavy calcium carbonate, the cellulose fiber stock solution comprises a plurality of cellulose fibers and water, the composition comprises a wet strength additive or wet web strength Improves the performance of additives or drainage additives,
At least a portion of the composition is added to the filler with a spin mixing device having a dispensing head, the spin mixing device is rotated by a drive, arranged in a container containing a slurry of filler particles, associated with a spinning surface, The head has a dispensing outlet along which the composition is provided with a slurry and a mixing blade,
Wherein the dispensing outlet is formed as an opening and the mixing blade is formed as a strip extending transversely to the plane of rotation and having a length equal to at least half of the inner diameter of the slurry pipe. The method of claim 1, wherein the paper mat is formed by removing a portion of the water from the formulation. The method of claim 1 wherein at least a portion of the calcium carbonate is in one form selected from the list consisting of undispersed calcium carbonate, dispersed slurry calcium carbonate, chalk, and any combination thereof. 3. The method of claim 1 wherein at least a portion of the calcium carbonate is in the form of a slurry calcium carbonate dispersed and the dispersed slurry calcium carbonate is at least one selected from polyacrylic acid polymer dispersant, sodium polyphosphate dispersant, kaolin clay slurry, ≪ / RTI > The method of claim 1, wherein the blend of filler particles is 50% heavy calcium carbonate and 50% precipitated calcium carbonate. The method of claim 1, wherein the composition is a coagulant. The method of claim 1, wherein the composition is a coagulant selected from the list consisting of an inorganic coagulant, an organic coagulant, a condensation polymerization coagulant, and any combination thereof. The method of claim 1, wherein the composition is a coagulant having a molecular weight range from 200 to 1,000,000. The composition of claim 1 wherein the composition is selected from the group consisting of alum, sodium aluminate, polyaluminum chloride, aluminum chlorohydroxide, aluminum hydroxide chloride, polyaluminum hydroxychloride, sulfated polyaluminium chloride, (EPI-DMA), EPI-DMA ammonia cross-linked polymers, polymers of ethylene dichloride and ammonia, polymers of ethylene dichloride, polymers of dimethylamine, polyfunctional diethylene < RTI ID = 0.0 > Polycondensation polymers of triamine, condensation polymers of polyfunctional tetraethylenepentamine, condensation polymers of polyfunctional hexamethylenediamine, condensation polymers of polyfunctional ethylene dichloride, melamine polymers, formaldehyde resin polymers, cationically charged vinylated polymers, How The method of coagulant selected from a list consisting of the combination. The method of claim 1, wherein the composition is a AcAm / DADMAC copolymer. The method of claim 1, wherein the drainage additive or wet web strength additive or wet strength additive is selected from the group consisting of glyoxylated acrylamide / DADMAC copolymers, poly-vinylamines, poly-vinylamides, poly-diallylamines, One method selected from the list. The method of claim 1, wherein the ratio of the drain additive or wet web strength additive or wet strength additive to the solids portion of the paper mat is 0.3 to 5 kg of strength additive per tonne of paper mat. The method of claim 1, wherein at least a portion of the GCC particles are treated with the composition. The method of claim 1, wherein the PCC particles are not treated with the composition. The method of claim 1, wherein the paper mat has a solids portion and the filler particles in the paper mat occupy more than 50% of the combined mass of solids portions of the paper mat. The method of claim 1, wherein the wastewater additive or wet web strength additive or wet strength adjuvant and composition have the same charge. The method according to claim 1, wherein the blend of filler particles further comprises one substance selected from the list consisting of organic pigments, inorganic pigments, clay, talc, titanium dioxide, alumina trihydrate, barium sulfate, magnesium hydroxide, ≪ / RTI > A papermaking process comprising the use of a filler,
Providing a blend of filler particles, at least one dry strength aid, and a cellulose fiber stock solution,
Treating the filler particles with the composition in the absence of a cellulose fiber stock solution,
Combining the filler particles with the cellulose fiber mother liquor,
Treating the formulation with at least one dry strength adjuvant,
Forming a paper mat from the formulation; and
And delivering the composition to a dispensing head for mixing into a filler slurry,
At least 10% of the filler particles are in the form of dispersed slurry calcium carbonate,
The cellulose fiber stock solution contains a plurality of cellulose fibers and water,
The composition improves the performance of the dry strength adjuvant in the paper mat,
At least a portion of the composition is added to the filler with a spin mixing device having a dispensing head, the spin mixing device is rotated by a drive, arranged in a container containing a slurry of filler particles, associated with a spinning surface, The head has a dispensing outlet along which the composition is provided as a slurry and mixing blade,
Wherein the dispensing outlet is formed as an opening and the mixing blade is formed as a strip extending transversely to the plane of rotation and having a length equal to at least half of the inner diameter of the slurry pipe. As a method for increasing the interaction between the cellulosic fibers and the wetting additive or the wet web strength additive or the wet strength adjuvant,
Pretreating the filler particles with the composition in the absence of a cellulose fiber mother liquor,
Blending the pretreated filler particles with the cellulose fibers,
Treating the blend with at least one wastewater additive or wet web strength additive or wet strength adjuvant,
And delivering the composition to a dispensing head for mixing into a filler slurry,
The filler particles are selected from the list consisting of precipitated calcium carbonate, heavy calcium carbonate, and any combination thereof,
The composition prevents the wastewater additive or wet web strength additive or wet strength adjuvant from adhering to the filler particles,
At least a portion of the composition is added to the filler with a spin mixing device having a dispensing head, the spin mixing device is rotated by a drive, arranged in a container containing a slurry of filler particles, associated with a spinning surface, The head has a dispensing outlet along which the composition is provided as a slurry and mixing blade,
Wherein the dispensing outlet is formed as an opening and the mixing blade is formed as a strip extending transversely to the plane of rotation and having a length equal to at least half of the inner diameter of the slurry pipe.

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