KR102220315B1 - 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, increasing sheet wet web strength, increasing sheet wet strength, and promoting filler retention in a paper making process. The method improves the efficiency of the drainage aid or wet web strength aid or wet strength aid by coating at least some 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 aid holds the cellulose fibers tightly together and is not wasted on the filler particles.

Description

[A METHOD OF IMPROVING DEWATERING EFFICIENCY, INCREASING SHEET WET WEB STRENGTH, INCREASING SHEET WET STREGNTH AND ENHANCING] FILLER RETENTION IN PAPERMAKING}

Background of the invention

The present invention relates to a method for improving dewatering efficiency, increasing sheet wet web strength, increasing sheet wet strength, and enhancing filler retention in a paper making process. Typically, in the papermaking process, chemicals are added to the wet end to aid in dehydration of the slurry, increasing retention, and improving the wet or dry sheet strength. The wet part of the papermaking process refers to a stage in the papermaking process in which the fibers are dispersed in the form of a slurry in water. The fiber-water slurry then proceeds to a drainage and dewatering 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 contain water and solids, typically 4 to 8% water. The solids portion of the paper mat contains fibers (typically, cellulose-based fibers) and may also contain fillers.

Fillers are mineral particles added to the paper mat during the paper making process to improve the opacity and light reflective properties of the resulting paper. Some examples of fillers are described in US Pat. 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 one or more of kaolin clay, talc, titanium dioxide, alumina trihydrate, barium sulfate, magnesium hydroxide, pigments such as calcium carbonate, and the like.

Calcium carbonate fillers come in two forms: GCC (ground calcium carbonate) and PCC (precipitated calcium carbonate). GCC is a natural calcium carbonate rock, and PCC is a synthetically produced calcium carbonate. Since these have a larger specific surface area, PCC has a greater light scattering ability and provides better optical properties to the resulting paper. However, for the same reason, the PCC filled paper mat produces paper that is weaker than the GCC filled paper in dry strength, wet strength and wet web strength.

Fillers are generally much smaller than fibers, and thus fillers have a much larger specific surface area than fibers. One of the challenges 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 wet chemicals such as dehydration aids, wet web strength aids and wet strength aids. The present invention is to provide a novel filler pretreatment to reduce the adsorption of wet chemicals onto the filler surface and thereby increase the efficiency of wet chemicals such as dehydration aids, wet web strength aids and wet strength aids.

Paper wet web strength is very important to paper producers, as increased paper wet web strength will increase machine runnability and reduce sheet break and machine downtime. The paper wet web strength depends on the number and strength of bonds formed between the woven fibers of the paper mat. Filler particles with a larger surface area are more likely to engage these fibers and impede the number and strength of these bonds. Due to its larger surface area, PCC fillers interfere with this bonding more than GCC.

Paper dewatering efficiency is also very important for paper producers, as the reduced dewatering efficiency in the wet part increases the steam demand for drying operations and reduces machine speed and production efficiency. Dehydration aids are widely used to improve dewatering efficiency to reduce energy consumption and increase machine speed and production efficiency.

Brief summary of the invention

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

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

Treating the filler particles with the composition in the absence of cellulose fiber mother liquor,

Blending the filler particles with the cellulose fiber mother liquor,

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

Forming a paper mat from the blend and

Delivering the composition to a distribution head for mixing into the 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 mother liquor comprises a plurality of cellulose fibers and water, and the composition is a wet strength aid or wet web strength on a paper mat. Improve the performance of additives or drainage additives,

At least a portion of the composition is added to the filler by a rotating mixing device with a dispensing head, the rotating mixing device being rotated by the drive, arranged in a container containing the slurry of filler particles, associated with the rotating surface, and dispensing surrounding the axis of rotation The head has a distribution outlet along its periphery through which the composition is provided to the slurry and mixing blade,

The dispensing outlet is formed as an opening, and the mixing blade is formed as a strip extending transversely to the rotating surface and having a length equal to at least half the inner diameter of the slurry pipe.

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

The detailed description of the invention is hereinafter described with specific reference to the drawings:
1 is a cross-sectional view of a device used to supply the present invention to a slurry of filler particles.
2 is an exploded view of a cross-sectional view of a device used to supply the present invention to a slurry of filler particles.
In the present description, like reference numerals in the drawings will represent 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 method comprising a filler. In at least one embodiment of the present invention, the papermaking method comprises the steps of producing a filler blend of PCC and GCC, wherein the PCC comprises at least 10% by mass of filler and GCC comprises at least 10% by mass of filler, Pre-treating at least a portion of the filler particles with a wet web strength additive or drainage aid or a coating that reduces the adhesion between the wet strength aid and the filler particles, the filler blend and wet web strength additive or both a drainage aid or wet strength aid to paper. And adding to the mat.

The addition of a wet web strength additive or a drainage aid or a wet strength aid to the paper mat is to increase the wet web strength of the formed paper, increase drainage, improve the machine speed and processing capacity, or increase the sheet wet strength. It has been known for a long time. Some examples of wet strength aids, wet web strength additives and drainage aids are described in US Pat. Nos. 7,125,469, 7,615,135, and 7,641,776.

Unfortunately, it is not practical to add large amounts of wet strength aids or wet web strength additives or drainage aids to compensate for the weaknesses caused by the large amount of filler in the paper mat. One reason is that such additives are expensive, and large amounts of additives will cause production costs that are not commercially viable. In addition, adding too much additives adversely affects the papermaking process and impairs the operability of various types of papermaking equipment. Additionally, cellulose fibers are capable of adsorbing only limited amounts of wet strength aids or wet web strength additives or drainage aids. This imposes a limit on how many supplements can be used. One reason why this is so is that wet strength aids or wet web strength additives or drainage aids tend to neutralize the anionic fiber/filler charge, and if these charges are neutralized, further adsorption of such additives is inhibited. to be.

In addition, adding a filler to the paper mat also reduces the effectiveness of the wet strength aid or wet web strength additive or drainage aid. Such additives tend to coat the filler particles. The more filler particles present, the more the additive coats the filler particles, and thus less wet strength aid or wet web strength additive or drainage agent that can be used to bond the cellulose fibers together. Because there is the maximum amount of wet strength aid or wet web strength additive or drainage agent that can be added, more fillers always mean less effective strength additives. This effect is more severe with PCC than with GCC because the higher surface area of PCC is coated with more additives than with GCC.

In at least one embodiment of the present invention, at least some of the filler particles are pretreated with the composition to at least partially prevent adhesion of the wet strength aid or wet web strength additive or drainage aid to the filler particles. Pretreatment contemplates completely coating some or all of the one or more filler particles with the composition. Alternatively, the pretreatment contemplates applying the composition only to a portion of one or more filler particles, or completely coating some filler particles and applying the composition only to a portion of certain other particles. In at least one embodiment, the pretreatment is carried out with at least a portion of the composition described in US Pat. No. 5,221,435, in particular of the cationic charge-biasing species described in that patent. In at least one embodiment, the pretreatment is carried out with the diallyl-N,N-disubstituted ammonium halide-acrylamide copolymer described in US Pat. No. 6,592,718.

Although pretreatment of filler particles is known in the art, conventional methods of pretreatment of filler particles do not relate to the effect of wet strength aids or wet web strength additives or drainage aids on adhesion to the filler particles. In fact, many prior art pretreatments increase the adhesion of the strength additive to the filler particles. For example, US Pat. No. 7,211,608 describes a method of pretreating filler particles with a hydrophobic polymer. However, this pretreatment is not related to the adhesion between the strength additive and the filler particles, only splashing the water to compensate for the excess water absorbed by the strength additive. In contrast, the present invention reduces the interaction between wet strength aids or wet web strength additives or drainage aids and filler particles, and unexpectedly results in a significant increase in paper strength, sheet dewatering and machine running capacity.

When comparing the wet tensile strength of the presented paper to the percentage of filler in relation to the total solids portion of the paper mat used to produce the presented paper, the results clearly show that the sheet does not have wet strength aid 63700 (temporary wet strength aid) added. If not, it indicates that it has very weak wet strength. Velox was able to significantly increase the sheet wet strength. The sheet wet strength could not be increased only by pretreatment of the filler. However, filler pretreatment further enhanced Velox performance, which resulted in higher sheet wet strength.

When comparing the wet web tensile strength of the given paper to the percentage of filler with respect to the total solids portion of the paper mat used to produce the given paper, the relationship between increasing filler content and decreasing paper wet web strength is a linear relationship. . If no Nalco dehydration aid (wet web strength aid) 63700 is added, the paper sheet has very poor wet web strength. Sheet wet web strength can be significantly improved by using Nalco dewatering aid 63700. Filler pretreatment alone has a negligible effect on the strength of the paper wet web. However, filler pretreatment can further extend the performance of Nalco dehydration aid 63700, and an additional 20% wet strength improvement was achieved by filler pretreatment at lower ash content. For higher ash content, the performance of 63700 elongated even higher than 20%. This is because the reduction in the efficiency of the strength additives trapped on the filler particles was dispelled by the filler pretreatment.

At least some of the fillers covered 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 dry or dispersed slurry form, choke, precipitated calcium carbonate (PCC) in any morphology, and precipitated calcium carbonate in dispersed slurry form. GCC or PCC in the form of a dispersed slipper is typically formed using a polyacrylic acid polymer dispersant or a sodium polyphosphate dispersant. Each of these dispersants impart a significant anionic charge to the calcium carbonate particles. Kaolin clay slurries are also dispersed using polyacrylic acid polymer or sodium polyphosphate.

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

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

Some organic coagulants suitable as treatment compositions are formed by condensation polymerization. Examples of this type of polymer include epichlorohydrin-dimethylamine (EPI-DMA), and EPI-DMA ammonia crosslinked polymer.

Further coagulants suitable as treatment compositions are polymers of ethylene dichloride and ammonia, or of ethylene dichloride and dimethylamine with or without ammonia, polyfunctional amines, such as diethylenetriamine, tetra, prepared by condensation reaction. And condensation polymers of ethylenedichloride and polymers such as ethylenepentamine, hexamethylenediamine and the like, such as melamine formaldehyde resins.

Additional coagulants suitable as treatment compositions are cationic charged vinyl addition polymers such as (meth)acrylamide, diallyl-N,N-disubstituted ammonium halides, dimethylaminoethyl methacrylate and quaternary ammonium salts thereof, dimethylaminoethyl Acrylate and its quaternary ammonium salt, methacrylamidopropyltrimethylammonium chloride, diallylmethyl (beta-propionamido) ammonium chloride, (beta-methacryloyloxyethyl) trimethyl ammonium methylsulfate, quaternized poly Vinyllactam, vinylamine, and polymers, copolymers and terpolymers of acrylamide or methacrylamide which react to produce Mannich or quaternary Mannich derivatives. Preferred quaternary ammonium salts can be produced using methyl chloride, dimethyl sulfate, or benzyl chloride. Terpolymers may include anionic monomers such as acrylic acid or 2-acrylamido 2-methylpropane sulfonic acid as long as the total charge on the polymer is cationic. The molecular weights of these polymers, both vinyl-added and condensed polymers, range as low as a few hundred or as high as millions. Preferably, the molecular weight range should be about 20,000 to about 1,000,000. In at least one embodiment, the pretreatment is performed by a combination of any, part or all of any of the compositions described as suitable compositions for pretreating the filler particles.

In at least one embodiment, the wet strength aid or wet web strength additive or dehydration aid has the same charge as a composition suitable for treating the filler particles. When the two carry the same charge, the filler additive is less likely to adsorb the wet strength aid, wet web strength additive, or drainage aid on its surface. Wet strength aids, wet web strength additives or drainage aids encompassed by the present invention are any of the materials described in U.S. Patent No. 4,605,702 and U.S. Patent Application No. 2005/0161181 A1, and in particular various Glycosylated acrylamide/DADMAC copolymer compositions. An example of a glycosylated acrylamide/DADMAC copolymer composition is product # Nalco 63700 manufactured by the Nalco Company (Naperville, Illinois). Another example is an amine-containing polymer including allylamine/acrylamide copolymers and polyvinylamine, and more than one example is polyamide-polyamine-epichlorohydrin (PAE).

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

In at least one embodiment, at least some of the filler particles are pretreated using a rotary mixing device. The rotary mixing device includes a dispensing head configured and arranged to rotate as it disperses the treatment chemicals in the filler particles. In at least one embodiment, the rotary mixing device is the device described in US Pat. No. 5,993,670. The device is capable of mixing the coagulant liquid(s) into the process stream, where a distribution head rotated by the drive is arranged in the pipe/conduit through which a slurry of filler particles flows, is associated with the rotating surface, and surrounds the rotating axis. The dispensing head has a coagulant outlet and mixing blades distributed along its periphery and is connected with a coagulant liquid delivery conduit.

In at least one embodiment, the present invention is also the use of a device for mixing a flocculant liquid formed by a mixture of an activator and water, and its n addition is added to 100 parts of a filler slurry, wherein the flocculant liquid contains the required amount of activator. It relates to the use of being added 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 the case where the liquid and the filler mix with each other with good results. However, there are certainly many cases where this is not the case, and the case where the mixing device has not performed satisfactory mixing of the flocculant liquid and the filler. In known devices of the type mentioned above (DE-05 40 29 824), the coagulant outlet is formed as a hole or a nozzle, each mixing blade is formed as a journal-like projection, which crosses the rotating surface. The dimensions of the mixing blade and outlet in the direction are very small compared to the width of the filler slurry stream. In some cases, the mixing of the flocculant liquid into the slurry obtained with these devices is insufficient. That is, the added flocculant liquid is not sufficiently uniformly distributed in the slurry stream behind the apparatus and is not contained in the slurry in the amount necessary for satisfactory flocculation.

Therefore, it is an object of the invention to be an apparatus of the type described above in which a better mixing of the coagulant liquid into the slurry is achieved. The device according to the invention for achieving this object is characterized in that the coagulant outlet is formed as a slot, the mixing blade extends transversely to the rotating surface and is formed as a strip having a length corresponding to at least half the width of the slurry stream. To do.

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

In at least one embodiment, the configuration of the dispensing head of the device allows improved mixing and dispensing of the flocculant liquid in the slurry to be achieved. The coagulant liquid comes out of each slot in the form of a wide strip, into which the next mixing blade is inserted in the direction opposite to the direction of rotation and along its edge pulls the agglomerate liquid through the slurry as a foggy strip. . The flocculant liquid is delivered to the slurry as an intermittent rapid flow through the slots, and the slots and strips are arranged one after the other in the direction of rotation. The dimensioning of the lengths of the slots and blades depends on the diameter of the stream or distribution head.

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

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

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

The cross-section of each outlet slot can be varied along its length to control the amount of flocculant liquid that comes out. It is particularly effective and advantageous if the cross-sectional area of each outlet slot is increased toward the middle when viewed along its length. This shape of the outlet slot is used when the slot extends transversely to the stream direction as there is more slurry in the middle of the slurry pipe than in the side. Due to the uniform slot width, 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 has to be delivered in units of time, the wider the slots, and the smaller the amount of coagulant liquid that has to be delivered in units of time, the narrower the slots.

It is particularly effective and advantageous if the edge of each strip-shaped mixing blade extends approximately parallel to the inner contour of the slurry pipe to form a gap therebetween. The elongated strip-shaped mixing blades extending in the radial direction improve 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 the stone chips present in the slurry to pass through.

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

Particularly effective and advantageous embodiments of the invention are obtained in cases where the direction of rotation of the dispensing head drive can be varied. In the device according to the invention, the mixing blade is relatively large or protruding relative to the cross section of the slurry pipe, and thus, when the dispensing head rotates in the same direction for a long time, clogging into hard pieces and accumulation of fibers or threads Danger exists. 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 effective and advantageous if the outlet slots and strip-shaped mixing blades are alternated in the direction of rotation. In addition, it improves the mixing process. At least two outlet slots and at least two strip-shaped mixing blades are provided above the dispensing head in the direction of rotation.

In addition, it is particularly effective and advantageous if the inner cross section of the slurry pipe in the area 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 shrinkage of the slurry pipe and the associated increase in the flow rate of the slurry. The dispensing head has previously achieved a greater reduction in cross section available for the slurry.

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

A particularly effective and advantageous embodiment of the invention is that the dispensing head extends away from the slurry pipe, passes to the drive, and with a rotatably supported connector, which is connected to the flocculant liquid delivery conduit, and is further provided with an inlet opening. , The coagulant liquid transfer conduit is formed when it is rotatably supported in an open connection chamber. This mode of delivery of the coagulant liquid to the rotatable dispensing head ensures increased rigidity of the connecting tube and support of the connecting tube by simple means. This is made possible in the apparatus according to the invention due to the "stone grinding" cooperation of the strip-shaped mixing blade and the slurry pipe.

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

It is particularly effective and advantageous that the slurry can penetrate into the outlet slot if the flocculant liquid is not under pressure in front of the check valve, e.g. if the flocculant liquid pump is not working, if the check valve is arranged in the flocculant liquid delivery conduit. Do. The sealing and bearings in the connection chamber remain lubricated with the coagulant liquid when the coagulant liquid from the coagulant liquid pump is no longer under pressure.

Certain effective and advantageous embodiments of the invention are obtained when the dispensing head is driven at a rotation speed of 700 to 2,500 revolutions/min, preferably 1,000 to 2,000 revolutions/min. At these relatively high rotational speeds, the desired improved mixing and distribution of the flocculant liquid in the slurry occurs. At extremely low rotational speeds of less than 500 rotations/min, the strip or stream of flocculant liquid ceases. However, large speeds require excessively high costs to achieve the desired effect. In known devices of the type described above (DE-05 4029824), a flocculant stored in a reservoir can be used. It is further known to add fresh water to the available flocculants in liquid or powder form to obtain about 1% flocculant mother liquor (DE-05 39 01 292). Thereafter, the coagulant mother liquor is mixed with 4 to 10 parts by volume of make-up water in a filling station to obtain a coagulant in the form of a so-called commercial solution. These flocculants are added to the slurry in an amount of 18 to 20% of the amount of the filler slurry. That is, about 20 parts of the flocculant liquid in the form of a flocculant formulation are added to 100 parts of the filler particles. At this time, the flocculant-containing slurry, ie the conditioned filler, contains liquid 1/6 added by mixing of the flocculant liquid which is further added.

In known applications, for further processing of the flocculant formulation, large amounts of water are used, which is expensive. For processing, in addition to a device for obtaining the mother liquor, a device for obtaining a commercial solution is required, which leads to an additional cost associated with the device and an additional cost associated with the operation of the device. The flocculant and its water are delivered until they are mixed with the slurry, and the delivery requires energy, which is expensive. The water component of the flocculant is passed along with the slurry to a filter press, passed through the filter press, and finally has to be purified again. Thus, in known applications, an increased additional cost is associated with the water contained in the flocculant liquid.

Therefore, it is an object of the present invention to thereby improve the above-described process so that the costs associated with the use of a flocculant liquid or increasing its water content are eliminated. This object is achieved according to the invention by designing the above-described apparatus according to the invention in such a way that a maximum of 3 t of coagulant liquid should be provided for 100 t of filler slurry.

It has been found that the use of the dispensing head of the apparatus according to the invention allows the water component of the flocculant liquid to be removed without precluding the efficiency of the flocculant liquid mixed into the slurry. While in known applications a large amount of the water component is required to achieve a certain effect with a certain amount of additive, this is not necessary when the device of the invention is used. The cost associated with this water content is correspondingly eliminated as the water component of the flocculant liquid can be reduced very significantly. As less water is needed, less water has to be pumped and less water has to be purified.

The improved efficiencies achieved by the present invention can be described as follows, without claiming that the description is correct: the specific shape of the mixing blade of the apparatus of the present invention greatly decomposes the filler slurry particles of the slurry and thus forms The disassembled pieces that become open form an open fissure. The specific shape of the coagulant outlet ensures that the mixing of the filler and coagulant is enhanced by allowing the coagulant liquid to take the shape of a large surface film covering the newly opened thermode. The flocculant liquid according to the present invention is already mixed in a finely distributed state to further dilute the additive with a large amount of water, and it is not necessary to increase the flocculant liquid water component. Thus, according to a particular effective and advantageous embodiment of the invention, the flocculant liquid is used as the mother liquor, and the additive is mixed with water in a single step. Due to this embodiment, an additional station for further mixing with water is eliminated.

Referring now to FIGS. 1 and 2, in at least one embodiment, the device is mounted on the filler slurry conveying conduit/pipe 1, through which the filler slurry conveying conduit/pipe 1 is directed to the arrow 2 Flows in the direction The device can be mounted on the slurry pipe 1 by means of an elongated flange 3 and comprises a connection chamber 4 protruding from the flange 3. From the connection chamber 4, a dispensing head 6 extends into the slurry pipe 1, which is provided at the opposite end of the chamber 4 and is rotated by a drive 7 formed as an electric motor. The flocculant liquid conduit 8 is opened into the chamber 4 and a 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 connector 15 at the shaft extension 12 extending from the drive 7 and at the end wall of the connection chamber 4, and an axial face seal 16 is provided. And, through this, the shaft extension 13 is extended. The connecting tube 15 has a plurality of elongated inlet openings 17 through which the coagulant flows from the connecting chamber to the connecting tube. The connecting tube 15 protrudes into the connecting chamber 4, through which a flat sleeve 5 is provided on the flange 3, and the tubular distribution head 6 forms an integral part of the connecting tube 15 do. The dispensing head 6 is associated with the rotating surface 18 indicated by the dotted line. Each mixing blade 11 forms an arcuate edge 19, which limits a slot 20 for a slurry pipe 1 with a circular cross section at the corresponding blade position.

The above description may be better understood with reference to the following examples, which are presented for illustrative purposes and do not limit the scope of the present invention.

Example One

1(i) filler pretreatment:

Blends of filler particles were 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 20% solids content. 200 mL of the diluted filler blend was placed in a 500 mL glass beaker. Stirring was performed for at least 30 seconds before adding the coagulant. The stirrer was a R1342, 50 mm, EUROSTAR Digital overhead mixer with 4-blade propeller, both obtained from IKA Works, Inc. (Wilmington, North Carolina). The coagulant solution was slowly added after the initial 30 seconds of mixing while stirring at 800 rpm. The coagulant solution used was 4690. The dosage of coagulant was 1 kg/ton based on the dry filler weight. Stirring was continued at 800 rpm until all coagulant was added. Then, the stirring speed was increased to 1500 rpm for 1 minute.

1(ii) Use of filler:

Stocks were 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 retention aid. For pretreatment evaluation, the filler mixture was pretreated with Nalco coagulant 4690 before the filler was added to the stock. During handsheet preparation, 3kg/ton Nalco 63700 was added to improve the sheet wet web strength. The present inventors attempted to evaluate the effect of filler pretreatment on the compression dewatering performance of 63700 by measuring the sheet wet web strength. The hand sheet was compressed to a specific solid content (50%) by controlling the same pressure level at 60°C, and the time required to completely decompose the wet sheet in water under a shear force of 1000 RPM is expected to reflect the compression dehydration indirectly. Recorded for comparison with wet web strength. The results indicated that the sheet wet web strength can be significantly improved by the addition of 63700. Filler pretreatment could further enhance the sheet wet web strength by an additional 20% at lower ash content. For higher ash content, the performance of 63700 was much higher than 20%.

Example 2

A mechanical test was conducted, at which time the paper machine manufactured GAB300 at a machine speed of 900 m/min. 14% MXW cellulose fiber; 3% coated broke; 17% SOW; A composition was provided that was 12% uncoated Broke, 44% DIP and 10% ONP. In addition, the stock contained GCC. During the test, all wet part additives including 15/ton Nalco compression dehydration aid 63700, retention aid, sizing agent, and cationic starch were kept constant.

1) Increased filler retention:

The 4690 was gradually increased from 0.5 kg/ton to 2 kg/ton based on the filler. The online ash content was found to gradually increase by adding 4690 to the filler pipe. Obviously, there was an increase of 0.7 batch points from 15.6% to 16.3% through filler pretreatment. Typically, for the same grade production, the recorded ash content of DCS was about 12% without the use of Nalco 63700. It should be noted that the ash content improvement is only due to the filler ply. Therefore, the increase in ash content in the filler ply is estimated to be about 1.4% as the filler plies occupy half the basis weight of the final product. FPAR increased from 70% to 75%, which may explain why the final ash content was significantly improved.

2) Vapor pressure reduction:

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

During the test, about 1 hour after the filler was pretreated, 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 remained decreasing for several hours until the press load was reduced. This appears to indicate that the vapor reduction was not solely due to an increase in ash content. In addition, the reduction in steam need for this test is due only from such a ply since 4690 was applied only to the filler ply, so the total vapor reduction due to the increase in ash content alone should be less. Therefore, the results indicated that filler pretreatment could enhance the 63700 performance as a compression dewatering agent or wet web strength aid.

Those skilled in the art will appreciate that all of the methods previously described are also suitable for paper mats comprising other non-cellulosic fibrous materials, paper mats comprising mixtures of cellulose-based fibrous materials and non-cellulosic fibrous materials, and/or synthetic fibrous materials. It will be appreciated that it is applicable to the material.

Changes may be made in the construction, operation, and arrangement of the inventive methods described herein without departing from the concept and scope of the invention as defined in the claims. While the present invention can be implemented in a number of different forms, certain preferred embodiments of the present invention are described herein. This description is an illustration of the principles of the invention and does not limit the invention to the specific embodiments illustrated. In addition, the invention includes any possible combinations of some or all of the various embodiments described herein. All patents, patent applications, and other citations mentioned in this application or in any cited patent, cited patent, or other citation are incorporated herein by reference in their entirety. In addition, the invention contemplates embodiments that exclude any, some or all of the compositions, methods, components, elements or other portions of any citation.

The above is intended to be exemplary and not non-exclusive. This description will present a number of 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, wherein the term “comprising” means “including, but not limited to”. Those of skill in the art may recognize other equivalents to the specific embodiments described herein, for which equivalents are also intended to be covered by the claims.

This makes the description of preferred and alternative embodiments of the invention complete. Those of skill in the art may recognize other equivalents to the specific embodiments described herein, for which equivalents are intended to be covered by the claims appended hereto.

Claims (19)

A papermaking method comprising a filler, the method comprising
Providing filler particles, at least one wet strength aid, and a cellulose fiber stock,
Treating the filler particles with a composition in the absence of a cellulose fiber mother liquor, wherein the composition is a coagulant,
Blending the filler particles with the cellulose fiber mother liquor,
Treating the formulation with at least one wet strength aid,
Forming a paper mat from the blend, and
Delivering the composition to a distribution head for mixing the composition into the 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 mother liquor comprises a plurality of cellulose fibers and water, and the composition enhances the performance of the wet strength aid in the paper mat. Let,
At least a portion of the composition is added to the filler by a rotating mixing device with a dispensing head, the rotating mixing device being rotated by the drive, arranged in a container containing the slurry of filler particles, associated with the rotating surface, and dispensing surrounding the axis of rotation The head has a distribution outlet along its periphery through which the composition is provided to the slurry and mixing blade,
The dispensing outlet is formed as an opening, and the mixing blade is formed as a strip extending transversely to the rotating surface and having a length equal to at least half 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. The method of claim 1, wherein at least a portion of the calcium carbonate is in the form of a dispersed slurry calcium carbonate, and the dispersed slurry calcium carbonate is at least one selected from polyacrylic acid polymer dispersant, sodium polyphosphate dispersant, kaolin clay slurry, and any combination thereof. Methods of further comprising eggplant substances. The method of claim 1 wherein the filler particles are 50% heavy calcium carbonate and 50% precipitated calcium carbonate. The method of claim 1, wherein the composition is a coagulant selected from the list consisting of inorganic coagulants, organic coagulants, condensation polymerization coagulants, and any combination thereof. The method of claim 1, wherein the composition is a coagulant having a molecular weight range of 200 to 1,000,000. The method of claim 1, wherein the composition is alum, sodium aluminate, polyaluminum chloride, aluminum chlorohydroxide, aluminum hydroxide chloride, polyaluminum hydroxychloride, sulfated polyaluminum chloride, polyaluminum silica sulfate, Ferric sulfate, ferric chloride, epichlorohydrin-dimethylamine (EPI-DMA), EPI-DMA ammonia crosslinked polymer, polymer of ethylene dichloride and ammonia, polymer of ethylene dichloride, polymer of dimethylamine, polyfunctional diethylene Condensation polymer of triamine, condensation polymer of polyfunctional tetraethylenepentamine, condensation polymer of polyfunctional hexamethylenediamine, condensation polymer of polyfunctional ethylenedichloride, melamine polymer, formaldehyde resin polymer, cationically charged vinyl addition polymer, and these A method that is a coagulant selected from a list consisting of any combination. The method of claim 1 wherein the composition is an AcAm/DADMAC copolymer. The method of claim 1, wherein the wet strength aid is one selected from the list of poly-vinylamine, poly-vinylamide, poly-diallylamine, and any combination thereof. The method of claim 1, wherein the ratio of the wet strength aid to the solids portion of the paper mat is from 0.3 to 5 kg of strength additive per ton of paper mat. The method of claim 1 wherein at least some 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 make up more than 50% of the combined mass of the solids portion of the paper mat. The method of claim 1 wherein the wet strength aid and composition have the same charge. The method of claim 1, wherein the filler particles further comprise one material selected from the list consisting of organic pigments, inorganic pigments, clay, talc, titanium dioxide, alumina trihydrate, barium sulfate, magnesium hydroxide, and any combination thereof. How to. A papermaking method comprising the use of a filler, the method comprising
Providing filler particles, at least one dry strength aid, and a cellulose fiber mother liquor,
Treating the filler particles with a composition in the absence of a cellulose fiber mother liquor, wherein the composition is a coagulant,
Blending the filler particles with the cellulose fiber mother liquor,
Treating the blend with at least one dry strength aid,
Forming a paper mat from the blend, and
Delivering the composition to a dispensing head for mixing the composition into the filler slurry,
At least 10% of the filler particles are in the form of a dispersed slurry calcium carbonate,
The cellulose fiber mother liquor contains a plurality of cellulose fibers and water,
The composition enhances the performance of the dry strength aid on the paper mat,
At least a portion of the composition is added to the filler by a rotating mixing device with a dispensing head, the rotating mixing device being rotated by the drive, arranged in a container containing the slurry of filler particles, associated with the rotating surface, and dispensing surrounding the rotating shaft The head has a distribution outlet along its periphery through which the composition is provided to the slurry and mixing blade,
The dispensing outlet is formed as an opening, and the mixing blade is formed as a strip extending transversely to the rotating surface and having a length equal to at least half the inner diameter of the slurry pipe. A method of increasing the interaction between a wet strength aid and a cellulose fiber mixed with filler particles, the method comprising:
Pretreating the filler particles with a composition in the absence of a cellulose fiber mother liquor, wherein the composition is a coagulant,
Blending the pretreated filler particles with cellulose fibers,
Treating the formulation with at least one wet strength aid, and
Delivering the composition to a dispensing head for mixing the composition into the 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 wet strength aid from adhering to the filler particles,
At least a portion of the composition is added to the filler by a rotating mixing device with a dispensing head, the rotating mixing device being rotated by the drive, arranged in a container containing the slurry of filler particles, associated with the rotating surface, and dispensing surrounding the axis of rotation The head has a distribution outlet along its perimeter through which the composition is provided to the slurry and mixing blades,
The dispensing outlet is formed as an opening and the mixing blade is formed as a strip extending transversely to the rotating surface and having a length equal to at least half the inner diameter of the slurry pipe.
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