JP2002526681A - Acidic colloids in fine particle systems used in papermaking - Google Patents

Abstract

SUMMARY OF THE INVENTION A microparticulate system for use as a capture and drainage aid in making alkaline and acidic paper products comprises HMW flocculant polymer (6), acidic colloid (7), and a coagulant or MMW flocculant (5). The acidic colloid (7) comprises an aqueous solution of a water-soluble polymer or copolymer of melamine aldehyde, preferably melamine formaldehyde, and comprises from 0.0005% by weight based on the dry weight of solids in the furnish. It is present in amounts up to 0.5% by weight. The HMW flocculant polymer (6) can be added to the stock or furnish after the fan pump; and before the pressure screen (2); the acidic colloid (7) can be added after the pressure screen (2). The coagulant / MMW flocculant (5) added to the stock can be added before the fan pump (1). Alternatively, this order of chemical addition can be varied, ie the acidic colloid (7) can be added before or after the fan pump (1) or before the pressurized screen (2). The addition of a fine particle system to the furnish improves capture, drainage and sheet formation during papermaking.

Description

DETAILED DESCRIPTION OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to paper products having improved properties in the area of capture, drainage, and sheet formation, ie, improvements for use as auxiliaries in making paper or paperboard. To a fine particle system. More particularly, the present invention relates to a fine particle system that includes an acidic colloid as the fine particle or inorganic fine particle material of the fine particle system.

BACKGROUND OF THE INVENTION In the manufacture of paper or paperboard, a diluted aqueous composition, known as "furnish" or "stock", is sprayed onto a movable mesh, known as "draping net". The solid components of the composition, such as cellulosic fibers and inorganic particulate filler material, are drained or filtered through a sieving net to form a paper sheet. The percentage of solid material trapped on the web is known as "first channel trap" in the papermaking process. Drainage, capture and formation (D / R / F) aids are used in the papermaking process.

[0003] Entrapment is thought to be a function of different mechanisms, such as mechanical retraction, electrostatic attraction, and filtration by crosslinking between fibers and fillers in the furnish. Since both cellulosic fibers and many common filler materials are negatively charged, they are repelletized from one another. Generally, the only factor that tends to enhance capture is mechanical retraction. Therefore, trapping aids are generally used to improve the trapping of fibers and fillers in the screen. Powder and filler entrapment is important to the papermaker in ensuring entrapment of colloidally sized particles in a sheet.
The first channel capture (FPR) measures this ability of the capture program. Colloidal silica has been used in the past as fine particles in capture aids for alkaline fine paper. Silica must be used properly to enhance the capture of powders and fillers by trapping the colloidal material and forming a fine mass that quickly dewaters the pulp slurry.

[0004] Drainage relates to the rate at which water is removed from the stock or furnish as the paper sheet is formed. Drainage usually refers to the removal of water that occurs before the paper sheet is optionally pressed and subsequently formed into a sheet. Thus, drainage aids are used to improve the overall effectiveness of dewatering during the manufacture of paper or paperboard.

[0005] The formation relates to the formation of paper or paperboard sheets produced in the papermaking process. Formation is generally assessed by the variation in light transmission within the paper sheet. Greater variability indicates a "poor" formation and low variability generally indicates a "good" formation. In general, as the level of capture increases, the level of formation generally decreases from good formation to poor formation.

[0006] Improvements in the capture and drainage of paper or paperboard sheets, and formation properties are particularly desirable for several reasons, and most notably, productivity. Good trapping and good drainage make the paper machine run faster,
And allows to reduce machine stoppages. Good sheet formation reduces paper waste. These improvements are recognized by the use of capture and drainage aids. Capture and drainage aids are additives that are used to agglomerate the fine solids present in the stock or furnish to improve these parameters in the papermaking process. The use of such additives is limited by the effect of agglomeration in paper sheet molding. If more capture aid is added to increase the size of the solidification of the fine solid material, this will generally cause the density of the paper sheet to fluctuate, as described above, thereby producing a "poor" sheet ground. May result in a conflict. Excessive agglomeration can also ultimately form holes in the sheet and / or affect drainage so that a late loss of vacuum pressure can occur during the late stages of dewatering during the papermaking process. sell. Capture and drainage aids are generally added to the furnish at the wet end of the papermaking machine,
And in general, there are three types: (a) a single polymer; (b) two polymers; or (c) a microparticulate system that can include a flocculant and / or a coagulant.

[0007] Fine particle systems generally provide the best results as capture and drainage aids and have been extensively described in the prior art. In the past few years, bentonite clay and colloidal silica have been used to improve drainage, capture and formation.

Examples of publications describing microparticulate systems include: EP-B- in which bentonite is used as an inorganic material associated with a high molecular weight cationic polymer in a particular order of addition.
WO-A-94 / 26972, which describes that vinylamide polymers are used with organic materials and one of a variety of inorganic materials such as silica, bentonite, clay, and the like; WO-A-97 / 16598, in which kaolin is described to be used with various cationic polymers; and bentonite, silica or acrylic acid polymers are described as cationic dispersion polymers. European Patent EP 805 234, which is disclosed for use in conjunction.

US Pat. Nos. 4,305,781 and 4,753,710 disclose the use of high molecular weight nonionic and ionic polymers with bentonite clay to aid in dewatering and entrapment in papermaking. Is disclosed. U.S. Pat. No. 4,388,1
No. 50 and 4,385,961 teach the use of cationic starch and colloidal silica. U.S. Pat. Nos. 4,643,801 and 4,750,974 describe the use of cationic starch, high molecular weight anionic polymers, and colloidal silica during papermaking. US Patent 5,
185,062 describes anionic polymers which act as fine particles with high molecular weight cationic flocculants. US Patent No. 5,167,766 includes:
It is taught to use charged organic polymer microbeads as fine particles in papermaking.

[0010] The fine particle system generally includes a polymer flocculant with or without a cationic flocculant and a fine particle material. The fine-grained material improves the efficacy of the flocculant and / or produces a smaller, more homogeneous mass.

[0011] The use of melamine-formaldehyde (MF) acidic colloids for the wet strength of paper is well known. TAPPI Monograph No. 29, "Wet Strength on Paper and Paperboard", C.I. S. Maxwell, J .; P. Weidner is cited. U.S. Pat. No. 2,345,543 describes the preparation of stable melamine-formaldehyde acidic colloids. U.S. Pat. No. 2,485,080 includes incorporation of urea into condensation products. U.S. Pat. Nos. 2,559,220 and 2
, 986,489 teach the use of these colloids to increase the wet strength of the paper. U.S. Pat. No. 4,845,148 describes the use of amino-aldehyde acidic colloids with acrylamide to increase the dry strength of paper. U.S. Pat. No. 5,286,347 describes the use of melamine formaldehyde colloids for pitch control in papermaking. U.S. Pat. No. 4,461,858 describes the use of a polyvinyl alcohol-melamine formaldehyde colloid mixture for wet strength in paper. U.S. Pat. No. 4,009,706 teaches using a melamine formaldehyde colloid and a high molecular weight anionic polymer to aggregate raw sugar.

[0012] To achieve better runnability on papermaking machines and / or to obtain specific end-use paper properties such as improved sheet formation for improved printability and improved surface strength. In spite of the several fine particle systems currently available for use in paper mills, paper and paperboard are improved and formed by improving drainage and capture during the papermaking process. There remains a very real and substantial need for a fine particle system for improving sheet formation properties in a laminated sheet.

(Summary of the Invention) The present invention fulfills this need. The present invention relates to a fine particle system used as a trapping and drainage aid in a papermaking process.

According to a first aspect of the present invention, inorganic fine particles containing, in furnish, a high molecular weight polymer flocculant and an acidic colloid composed of an aqueous solution of a water-soluble polymer or copolymer There is provided a method of making paper, characterized by adding a fine particle system as a capture and / or drainage aid comprising the material.

According to a second aspect of the present invention, a fine particle system is added to the furnish as a capture and drainage aid, and the fine particle system comprises a high molecular weight polymer flocculant, and a water soluble polymer or copolymer. A fine particle system is provided that includes an inorganic particulate material that includes an acidic colloid composed of a coalesced aqueous solution.

According to a third aspect of the present invention, a paper or paperboard product is produced by adding a fine particle system to an aqueous cellulosic furnish, wherein the fine particle system comprises a high molecular weight polymer flocculant. Or paper having improved properties in the areas of trapping, drainage and formation, characterized in that it comprises an inorganic particulate material comprising an acidic colloid composed of an aqueous solution of a water-soluble polymer or copolymer. A paperboard product is provided.

[0017] A fourth aspect of the invention is a method wherein the steps include: a) adding a high molecular weight polymeric flocculant to the furnish dilute stream after the first shearing step; b) at least After the second high shear stage, adding inorganic particulate material including an acidic colloid composed of an aqueous solution of a water-soluble polymer or copolymer; (c) draining the furnish and removing the sheet Forming a water-based cellulosic furnish, comprising: (d) drying the sheet.

[0018] In some aspects of the invention, and in a preferred embodiment, the acidic colloid is comprised of an aqueous solution of a water-soluble polymer selected from the group consisting of melamine aldehyde, urea aldehyde, and melamine-urea aldehyde. , And aldehyde,
Lower formula

[0019]

Embedded image

Wherein R 1 is selected from the group consisting of linear and branched C _1-4 alkyl
It is. The acidic colloid is present in the stock or furnish in an amount ranging from about 0.0005% to about 0.5% by weight based on the dry weight of the solids in the stock or furnish. . Preferably, the aldehyde is formaldehyde and the acidic colloid is melamine formaldehyde, which can be etherified with a linear or branched alcohol.

The high molecular weight (HMW) polymer flocculant is present in an amount ranging from about 0.0025% to about 1.0% by weight based on the dry weight of solids in the furnish. I do. The high charge density cationic coagulant may be added to the stock or furnish prior to the first shearing step, or may be added, for example, before or after the addition of the acidic colloid. Alternatively, the acidic colloid and / or flocculant may be added to the stock or furnish prior to the HMW flocculant and / or coagulant and / or prior to the first shear stage.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the capture / drainage / formation (R / D) for specific applications at the wet end of a papermaking machine in the papermaking process for both acidic and alkaline fine papers. / F) directed to fine particle systems used as auxiliaries.

As used herein, the term “paper” includes paper sheets and products that include cellulosic sheet materials, including paperboard and the like.

The “fine particle system” of the present invention is at least one hydrophilic polymer used as an aggregating agent, and fine particles in the system, and at least one inorganic particle that is a coagulant in some cases. Refers to the combination with the material. In the present invention, the fine particle or inorganic particle material is an acidic colloid. The components of this combination may be added together with the stock or furnish to be treated, but preferably are added separately by the means and procedures described below.

The present invention can be performed using a conventional papermaking machine. According to conventional practice, the furnish or "dilute stock" drained to form a paper sheet is often
Made generally in a mixing or storage vessel by mixing pigment or filler material, suitable fibers, any desired reinforcing agents and / or other additives, and water, which may be recycled water It is made by diluting thick stock. The dilute stock can be washed by conventional means, for example, using a whirlwind washer. Usually, the dilute stock is washed by passing through a centrifugal screen. The dilute stock is typically pumped along the papermaking machine by one or more centrifugal pumps known as fan pumps. For example, the dilute stock may be pumped by a first fan pump to a centrifugal screen. The dilute stock is diluted with water before it enters this first fan pump or before the first fan pump, i.e. by passing the thick stock and dilution water through a mixing pump,
It can form a dilute stock. The dilute stock may be further washed by passing through a second centrifugal screen or pressure screen and passed through a headbox prior to the sheet forming step of the papermaking machine.

The sheet forming process may be performed on any conventional paper and paperboard forming machine, such as, for example, a flat fourdrinier device, a double screen forming device, or a bat forming device, or any of these forming machines. Any combination may be used. An approach system for a papermaking machine may include the components shown in a single drawing. These components include a fan pump 1, a pressure screen 2, and a headbox 3. By passing the thick stock and dilution water through a mixing pump (not shown), the thick stock is diluted with water to form a thin stock before entering the fan pump 1. sell. The dilute stock is cleaned of contaminants by passing it through the pressure screen 2 and the dilute stock leaving the press screen 2 is passed through the headbox 3 before forming the sheet.

The single drawing also illustrates preferred points of addition for the components of the microparticulate system of the present invention. Preferably, before the thin stock passes through the fan pump 1, a coagulant is added to the thin stock, the process of which is indicated by arrow 4 and the addition is indicated by arrow 5. As indicated by arrow 6, the flocculant is added to the dilute stock upon exiting fan pump 1, and the fine-grained particulate material, including the acidic colloid, is mixed with the dilute stock as indicated by arrow 7. Upon exiting the pressure screen 2, it is added to the thin stock. The fan pump 1 and the pressure screen 2 create a high shear stage on the paper machine.

In the present invention, the high molecular weight (HMW) polymeric flocculant of the fine particle system is preferably added before the dilute stock reaches the end point of high shear, and the resulting dilute stock is obtained. Is preferably sheared, for example, at the end of high shear and preferably before adding the finely divided acidic colloidal material of the present invention. In a single drawing, the flocculant is shown to be added before the dilute stock passes through the press screen 2 and the acidic colloid is added after the stock passes through the press screen 2 Indicates that

Preferably, the microparticulate HMW polymer flocculant of the present invention has a solids content of dilute rather than thick stock (ie, desirably no more than 2%, or most preferably, 3% by weight). Has). Thus, the HMW flocculant polymer can be added directly to the dilute stock or to the dilution water used to convert the thick stock to dilute stock.

High molecular weight polymer flocculants generally include agents for flocculating solids, especially fine powders, in the furnish. As used herein, "fine powder" means fine solid particles and fibers as defined in TAPPI Test Methods T261 and T269, respectively.

[0031] The agglomeration of the fine powder in the stock and furnish is carried out with the high molecular weight polymer itself or with a medium molecular flocculant or coagulant, which may be a high charge density cationic coagulant. Can be performed in combination. The agglomeration of the fines indicates that the fiber structure of the formed paper sheet is excellent for capturing fines, thereby providing improved dewatering and drainage.

The high molecular weight polymer flocculant is a polymer that provides the flocculant action, preferably by itself.

An example of a high molecular weight polymeric flocculant suitable for use herein is about 100,000
These have a weight average molecular weight of at least 500,000. Preferably, the weight average molecular weight is above about one million, and often above about five million, and is characteristically in the range of ten to thirty million or more. These polymers can be linear, branched, cationic, anionic, nonionic, amphoteric or hydrophobically modified polymers of acrylamide or other nonionic monomers.

The amount of the fine particle-based high molecular weight polymer flocculant added to the furnish in the present invention is:
The solids present in the furnish can be any amount that is sufficient to provide a substantial effect in agglomerating the fine powder. The total amount of water-soluble flocculant polymer added is about 0
. In the range from 0025% to about 1.0% by weight, more preferably 0.0%
In the range of 1% to 0.2% by weight, and most preferably about 0.012%.
It can range from 5% to about 0.1% by weight (dry weight of polymer based on dry weight of solids present in the furnish). The addition may take place at one or more addition sites in one or more doses, and may preferably be made in a single dose to the dilute stock flow after the fan pump, It causes a high shearing action.

Desirably, the mass formed by the high molecular weight polymeric flocculant is subjected to a shearing action before adding the acidic colloid of the fine particles of the present invention. Preferably, this shearing action is induced by a pressure screen where high shearing action is induced.

In the present invention, the acidic colloid is composed of an aqueous solution of a water-soluble polymer or copolymer. In a preferred embodiment, any melamine aldehyde type polymer or copolymer can be used. Preferably, the polymer is a) melamine or substituted melamine; and b)

[0037]

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Wherein R 1 is selected from the group consisting of straight and branched chain C _1-4 alkyl
It is produced by using an aldehyde having Preferred aldehydes are methanal (formaldehyde), ethanal, propanal, glyoxal, and glutaraldehyde, and the most preferred aldehyde is formaldehyde.

The molar ratio of component a) to component b) above should range from about 1: 1 to about 1:10, with a preferred ratio being from about 1: 3 to 1: 6. The most preferred molar ratio is about 1 mole of melamine or a derivative thereof to about 3 moles of aldehyde. Thus, the most preferred polymer is made from melamine and formaldehyde, and the molar ratio of melamine to formaldehyde is about 1: 3.

The melamine aldehyde type polymers of the present invention are insoluble in water, but can be maintained in a colloidal suspension in an acidic solution. Any acid or suitable combination of acids, preferably hydrochloric acid, may be used to produce the melamine aldehyde acidic colloid. The active content of the melamine aldehyde type polymer in the acidic suspension or solution is
It should range from about 0.1% to about 20%, preferably from 1% to about 15%, and most preferably from about 4% to about 12%. The pH should be low enough using aqueous minerals or organic acids to retain the melamine aldehyde type polymer in the finely divided colloidal suspension, ie between 1.0 and 2.5 .

A urea aldehyde type polymer solution suitable for use in the present invention is
As defined above, most preferably a urea-formaldehyde solution. The molar ratio of urea to aldehyde should be in the range from 1: 1 to 1:10, with the most preferred ratio being from 1.3 to 1: 6.

[0042] Melamine urea aldehyde copolymer solutions can also be used in the present invention. These solutions are made from an aldehyde component, urea, and melamine or substituted melamine as described above. Preferably, it is a melamine-urea-formaldehyde copolymer solution. Melamine-urea-aldehyde copolymer solutions suitable for use in the present invention include, for each mole of mixed melamine and urea in an acidic aqueous solvent, 1 to 70 mole percent urea, 30 to 99 mole percent melamine, and It contains up to about 1 to 4 moles of aldehyde. Copolymer solutions for use in the present invention are in the range of 0.1 to 20 percent solids, and preferably 1 to 12 percent solids.

The acidic colloid of the present invention may be a copolymer containing melamine aldehyde and a condensate containing amelin-aldehyde, dicyandiamide aldehyde, biguanidine-aldehyde, urea formaldehyde polyalkylene polyamide, and polyureide. .

Acidic colloids are prepared by reacting an amine with a specific aldehyde and curing the solution under acidic conditions, generally using hydrochloric acid. As curing progresses, the colloidal particles grow to a size of 20 to 200 angstroms. The average degree of polymerization is from 10 to 20 methylolated melamine units. The particles carry a cationic charge, i.e., some of the secondary amine units
Protonated. Colloidal solutions characteristically exhibit a blue haze. The solution
Store at a concentration of 8-12% active polymer. The solution may consist exclusively of amines and aldehydes, or may be a derivative thereof. The solution is alcohol,
It can be partially etherified with glycols or other hydroxyl containing species. The solution is
It may be a co-condensate of melamine-formaldehyde and another aminoplast, which may then be etherified. The solution can be a mixture of such aminoplasts and is then used to form an acidic colloid. The aminoplast that forms the colloid can also be a copolymer of monomers unsaturated with ethylene, such as acrylamide, dimethylaminoethyl acrylate, diallyldimethylammonium chloride, or methacrylamidopropyltrimethylammonium chloride. In the present invention, these acidic colloids are used herein as part of a fine particle drainage, capture and formation program related to making paper or paperboard.

In a preferred embodiment, the acidic colloid may be those disclosed in the aforementioned US Pat. No. 5,382,365, which is incorporated herein by reference. The amount of acidic colloid added to the furnish is from about 0.0005% to about 0.5% by weight, based on the dry weight of the paper stock or solids present in the furnish, and preferably , From about 0.005% to about 0.25% by weight. This addition can be made in one or more doses at one or more feed points or sites of addition, but is preferably in one dose, and preferably
It can be performed after the pressing screen 2 in the figure and at least between the pressing screen 2 and the head box 3. The acidic colloid of the fine particle system of the present invention is preferably a melamine-formaldehyde acidic colloid.

The addition of a high molecular weight (HMW) polymer flocculant generally causes the formation of large lumps of suspended solids in the furnish to which the polymer is added. These big chunks
Immediately or continuously by high shear, it is crushed into very small chunks known in the art as "fine chunks". This "high shear" is caused by passing the agglomerated furnish through the press screen 2 of the drawing.

In general, a water-soluble polymer having a lower molecular weight than the flocculant can be used as a coagulant by adding it to the thick stock, and preferably the furnish is used before the furnish passes through the fan pump 1. Added to the ingredients. The coagulant may be a high charge density cationic polymer. For example, when the coagulant polymer is a nitrogen-containing cationic polymer, the equivalent nitrogen per kilogram of polymer is about 0.2, preferably at least 0.35, and most preferably 0.4 to 2. It may exhibit a charge density of 5 or more. If the polymer is optionally formed by polymerization of a cationic, ethylenically unsaturated monomer with other monomers, the amount of cationic monomer will depend on the amount of monomer used to form the polymer. Normally, about 2 mole%, and usually about 5 mole%, and preferably at least about 10 mole%, based on the total amount
It is.

[0048] Both natural and synthetic inorganic and organic coagulants can be used in the microparticulate system of the present invention. Where the coagulant is a cationic, suitable cationic coagulants include polydiallyldimethylammonium chloride (p-DADMAC); polyalkylamines; dimethylamine and / or ammonia or other primary and secondary amines and Cationic polymers of chlorohydrin; polyamidoamines; copolymers of cationic monomers such as DADMAC or acryloyloxyethyltrimethylammonium chloride with nonionic monomers such as acrylamide; cyanoguanidine modification of urea / formaldehyde resins Melamine / formaldehyde polymer; urea / formaldehyde polymer; polyethyleneimine; cationic starch; cationic aluminum salts of monomers and polymers; amphoteric polymers that handle total cationic charge; Blend of agents.

[0049] The amount of the microparticulate coagulant of the present invention added to the stock or furnish is sufficient to provide a substantial effect in coagulating the solids present in the furnish. Any amount. The total amount of the water-soluble coagulant polymer is from about 0.0025% by weight to about 1%.
. It can range up to 0% by weight, more preferably from 0.005% to 0.50% by weight (dry weight of polymer based on dry weight of solids present in the furnish). .

If a medium molecular weight (MMW) flocculant is used instead of the cationic coagulant, the coagulant can be added before the stock passes through the fan pump 1. Examples of MMW coagulants suitable for use in the present invention are those having a weight average molecular weight ranging from 500,000 to between about 5 and 6 million. The chemical additive can be acrylamide or a copolymer of any unsaturated monomers.
Suitable MMW coagulants include Calgon Corporation (Pennsylvania)
ECCat® 500 copolymer available from Co., Ltd.

[0051] The amount of MMW coagulant can be any amount sufficient to provide a substantial effect in coagulating the solids present in the paper or furnish. The total amount of MMW coagulant ranges from about 0.0025 to about 1.0, based on the dry weight of solids present in the furnish.
It can be in the range up to% by weight. Application rates range from 0.01 to 5.0 pounds / ton of polymer.

As mentioned above, a coagulant or MMW flocculant can be added to the thick stock before the fan pump 1. The HMW flocculant polymer can be added to the dilute stock after the flow of the stock through the fan pump 1 and the acidic colloid of the present invention can be added to the stock after the flow of the stock through the pressure screen 2, Can be added to dilute stock. Alternatively, these chemical additives may be added to the stock in a different order and / or at a different feed point than shown in the figures.

The original thick stock is a traditional chemical pulp, for example bleached and unbleached sulfate or sulphite pulp; a mechanical pulp, such as broken wood pulp; a thermomechanical pulp; or a chemical thermochemical pulp; Or it can be made from any conventional papermaking process, such as recycled pulp, such as an inked waste fiber filler composition obtained from a coagulation or regeneration process; and any mixtures thereof.

The stock or furnish used in the present invention and in the final paper is substantially unfilled (eg, contains less than 10% by weight and generally less than 5% by weight filler in the final paper). Or filled with a filler that can be supplied in an amount up to 50% by weight based on the dry weight of the stock solids, or in an amount up to 40% by weight based on the dry weight of the paper solids. sell. If a filler is used, any conventional white dye filler such as calcium carbonate, kaolin clay, calcined kaolin, titanium dioxide, or talc, or combinations thereof, may be present. Fillers, if present, are preferably incorporated into the furnish in a conventional manner and before adding the components of the microparticulate system of the present invention.

The stock or furnish used in the present invention includes other known optical additives such as rosin, alum, neutral sizing agents or optical fluorescent agents. that is,
It may include a strengthening or binding agent, and may include, for example, a starch such as a cationic starch. The pH of the stock generally ranges from about 4 to about 9.

The amounts of fibers, fillers, and other additives such as reinforcing agents or alum,
All are as before. Typically, the dilute stock has a solids content of 0.1% to 3% by weight, or a fiber content of 0.1% to 2% by weight. The dilute stock usually has a solids content of from 0.1% to 2% by weight. These contents are based on the dry weight of solids in the stock.

The acidic colloid used as the particle material of the fine particles in the fine particle system of the present invention is preferably a melamine-formaldehyde acidic colloid or a derivative thereof. Preferably, the acidic colloid is composed of an aqueous solution of a water-soluble polymer or copolymer, and is preferably melamine aldehyde, preferably melamine formaldehyde. These particles are easily dispersed in the aqueous pulp suspension in a papermaking process that enhances the surface properties of the final paper product. These particles generally have an average particle size of about 10 to about 20 nm.

The inventors have found that an acidic colloid, melamine formaldehyde, together with a flocculant and a coagulant, can increase drainage and entrapment in the papermaking process and improve sheet formation.

Experiments The following examples illustrate the invention in more detail and are not intended to limit the scope of the invention in any way. In the examples, melamine formaldehyde is compared to colloidal silica as fine particles. Cationic starch was used as cationic coagulant. The following products were used in these examples: Anionic Flocculant-Calgon Corporation, comprising about 70% by weight acrylamide and about 30% by weight acrylic acid.
) (28% by weight active anionic acrylamide-acrylic acid copolymer available from Pittsburgh, PA). Melamine-Formaldehyde (MF) acidic colloid-8% active solution available from Calgon Corporation (Pittsburgh, PA). Colloidal silica-15% active solution available from Nalco (Naparville, IL). Calbital 60-ECC International, Inc. (ECC Inte
national, Inc. ) (Dry submarine calcium carbonate available from Atlanta, Georgia). Registered trademark Stalok 400 and Interbond CA. E. FIG.
Cationic starch available from A.E. Staley. (Registered trademark Stallock is a federally registered trademark of AE Starley). Hercon 70-Heracles, Inc. (Hercules, I
nc. AKD (alkyl ketene dimer) size available from).

Examples 1 to 23: Alkaline Fine Furnish Furnish Preparation Synthetic alkaline furnish was manufactured and used in drainage and capture tests and when making handsheets. The following ingredients were used: Fiber: 50/50% by weight bleached hard wood kraft paper / bleached soft wood kraft paper Filler: 50/50% by weight seabed calcium carbonate (Carbital 60) / precipitated calcium carbonate. Filler loading: 20% by weight based on fiber solids Starch: 0.5% by weight based on fiber solids (Interbond C (I
nterbond C)) Size: 0.25% by weight Herkon 70 (AKD) Dried wrapped pulp is soaked in warm water for 10 minutes, diluted with water to a consistency of 2% by weight solids, and 590 ml of Canadian Standard Free To the degree (CSF), it was purified or agitated in a laboratory-scale Voice Allis Valley refining machine. Starch, sizing and filler were added to the refined pulp slurry in this order. The pH of the pulp slurry was generally 7.5 ± 0.3. The pulp slurry was further diluted with tap water to approximately 1.0% by weight consistency to form a dilute stock for testing. The furnish is representative of the typical alkaline fine furnish used for printing and document grade paper, and was used in Examples 1-23.

Drainage Testing Procedure 1.1 200 ml (2 g solids) furnish at 1.1 wt% headbox consistency was
Poured into a square mixing jar and diluted to 500 ml with tap water. 2. The contents are pumped to the second fan pump inlet, fan pump outlet, and pressurized screen outlet with the following mixing times (seconds) and speeds (r
pm) using a standard brit jar type mixing device with a propeller (1 inch in diameter).

Time rate (rpm) additive feed point t ₀ 1200 before starch fan t ₁₀ 1200 flocculant before screen t ₂₀ 600 after acidic colloid screen t ₃₀ stop The contents in the mixing jar were transferred to a 500 ml graduated drain tube fitted to the bottom with a 100 mesh screen. The tube was inverted five times to ensure that the stock was homogeneous. Remove the stopper at the bottom of the tube and 100,
Elution times were measured for 200 and 300 ml elution volumes. The elution time at a volume of 300 ml for the untreated stock blank should preferably be greater than 60 seconds. 4. The improvement in wastewater provided by the treatment was calculated as follows based on the drainage time for the untreated blank sample. Drainage improvement rate (%) = (Drainage time without treatment−Drainage time treated) / Drainage time without treatment × 100% The results of the drainage pipe test are shown in Table 1.

Capture Test Means (FPR, FPAR, FPFR) —TAPPI Test Method T269 500 ml of furnish in headbox consistency (1.0%) at 1200 rpm
While stirring the stock at m, it was poured into a brit jar having a 70 mesh screen. 2. The mixing time / speed (seconds / rpm) sequence, the following load: at t _30, in order to stimulate the chemical load point (opening the bottom of the stop cock, and collects the eluate of the first 100ml) , Similar to those used in the drainage test means above. 3. The eluate was filtered through Whatman # 4 filter paper,
And it dried at 105 degreeC. 4. The pad was burned at 600 ° C. for 2 hours and the ash residue was measured. The results for the residual test are shown in Tables 2 and 3.

Production and Testing of Handmade Sheets Handmade sheets were prepared using a Noble & Wood hand sheet mold (Noble & Wo).
o Hand Hand Sheet Mold)
Manufactured in grams. This device produces a 20 cm × 20 cm square handmade sheet. Mixing time / speed (seconds / rpm) used in manufacturing handmade sheets
) The order was the same as that used for the drainage test means. The processed furnish samples were poured into a deckle box on a Noble & Wood handsheet machine, and the sheets were manufactured using standard techniques well known by those skilled in the art.

Sheet Properties Sheet formation was measured on handmade sheets using an MK System Formation Tester, Model M / K950R.

Examples 1 to 8: Drainage The data in Table 1 below show that the acidic colloids in the microparticulate system of the invention together with an anionic HMW flocculant and melamine-formaldehyde (MF) at 10 and 20 lb /. 2 shows the improvement of drainage observed when using tons of cationic starch. The cationic starch is fed before the fan pump, the anionic flocculant is fed before the screen, and the MF is fed after the screen, as described above for the mixing time and speed sequence in the drainage test means. Supplied.

The data in Table 1 shows important findings in the use of MF as fine particles in the papermaking process. In general, colloidal silica (prior art fine particles) requires more than 10 pounds / ton of cationic coagulant or starch to be an effective drainage aid in paper manufacture. The results in Table 1 show that the use of an acidic colloid, such as melamine formaldehyde, with an anionic flocculant reduces the amount of cationic starch or coagulant required in the paper mill and increases the It appears to indicate that the desired level of drainage in a papermaking machine can be achieved. At high loadings of melamine formaldehyde, 20 lb / ton of cationic starch appears to be beneficial, but drainage levels are not sufficient to achieve acceptable "machine" sheet formation. Can be considered "too high". This data can also show that by increasing the MF application, the drainage level can be increased to the desired level.

[0068]

[Table 1]

Examples 9 to 14 below show the colloidal silica present here as fine particle material and melamine formaldehyde (MF) as fine particle material of the present invention.
The comparison data between is shown.

Examples 9-14: First Channel Capture (FPR) In Table 2, Examples 9-14 show 10 lb / ton cationic starch and 0.5 lb / ton active anion. 5 shows that the effect from MF was enhanced compared to silica at the dosages indicated in connection with the first channel capture when using a flocculant.
Entrapment is in accordance with the mixing order discussed here above in the drainage test means, so that the brit (
(Britt) method (TAPPI test method T269).

[0071]

[Table 2]

Examples 15-20: First Channel Ash Capture (FPAR) The capture of micron sized fillers is also an important factor in the manufacture of paper products. Filler materials should be trapped in the sheet to reduce production costs, improve the optical properties in the sheet, and increase the efficiency of the papermaking machine. The capture of these micron sized fillers is measured by first channel ash capture (FPAR). Table 3 below shows colloidal silica (prior art) at the indicated dosages when using 10 lb / ton cationic starch and 0.5 lb / ton active anionic flocculant.
The effect obtained from MR (the present invention) is enhanced in comparison with the above.

[0073]

[Table 3]

It is generally known to those skilled in the art that drainage levels cannot generally be increased without the possibility of sacrificing properties in the sheet. During coagulation, the sheet generally
Poor optical properties and / or sheet formation may result. Currently, if the stock or furnish contains an excess amount of flocculant, or the flocculant is not properly used in the stock or furnish, or is not used at the appropriate feed point on the papermaking machine, Today's fine particle systems can cause severe sheet formation problems. Poorly formed sheets also have difficulty losing water (dewatering) in the press and / or dry section of the papermaking machine. As exemplified below in Examples 21-23, it has been observed that the use of melamine formaldehyde improves sheet formation, and that the dewatering step of the sheet in the press and / or drying section of the papermaking machine is An improvement can be implied when compared to fine particles of the preceding part, such as colloidal silica.

Examples 21-23: Formation Table 4 illustrates the advantages of using melamine formaldehyde (MF) as the particulate material of the fine particles, while using colloidal silica for sheet formation. (
The higher the forming index, the better the sheet formation. ) Generally, high levels of drainage are associated with a significant decrease in the molding index. As can be seen from Examples 22 and 23,
At equivalent drainage levels, melamine formaldehyde produced better sheet formation than prior art colloidal silica.

[0076]

[Table 4]

While specific embodiments of the present invention have been described for purposes of illustration, enormous variations and details of the invention may depart from the invention as defined in the appended claims. It will be clear to those skilled in the art that this can be done without.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a single diagram illustrating a portion of a typical papermaking machine, and the point at which the components of the fine particle system of the present invention are added in a preferred form.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL , IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZA, ZW (71) Applicant One Nelco Center , Naperville, Illinois 60563-1198, United States of America F-term (reference) 4D015 BA11 BA19 BB09 BB17 CA20 DB07 DB09 DB26 DB33 DC03 DC07 EA04 EA35 4L055 AG80 AG81 AG32 FA18

Claims (17)

[Claims] 1. A fine particle system for use as a capture and drainage aid in a furnish, comprising: a) from about 0.0025% to about 25% by weight based on the dry weight of solids in said furnish. A high molecular weight polymeric flocculant present in an amount up to 1.0% by weight, and b) from about 0.0005% to about 0.5% by weight based on the dry weight of solids in the furnish. A fine particle system comprising an acidic colloid comprising an aqueous solution of a water-soluble polymer or copolymer present in an amount of 2. The method according to claim 1, wherein the polymer is selected from the group consisting of melamine aldehyde, melamine is substituted or unsubstituted, and the aldehyde has the following formula: The system of claim 1, wherein R 1 is selected from the group consisting of linear or branched C _1-4 alkyl. 3. The system according to claim 2, wherein the aldehyde is selected from the group consisting of formaldehyde, ethanal, propanal, glyoxal, and glutaraldehyde. 4. The system according to claim 3, wherein the aldehyde is formaldehyde. 5. The system according to claim 1, wherein said water-soluble polymer is melamine-formaldehyde. 6. The system according to claim 5, wherein the melamine-formaldehyde is etherified with a linear or branched alcohol. 7. The method according to claim 7, wherein the melamine-formaldehyde is dissolved in an acidic aqueous environment.
The system of claim 5, which is at about 50% solids. 8. The system according to claim 1, wherein said acidic colloid is a copolymer of melamine-formaldehyde and urea-formaldehyde. 9. The method of claim 9, wherein said acidic colloid comprises said melamine-aldehyde and a condensate selected from the group consisting of amelin-aldehyde, dicyandiamide aldehyde, biguanidine-aldehyde, urea formaldehyde polyalkylene polyamine and polyureide. 2. The system according to claim 1, which is a polymer. 10. The acidic colloid is an amine-aldehyde type copolymer and is ethylene selected from the group consisting of acrylamide, dimethylaminoethyl acrylate, diallyldimethylammonium chloride, and methacrylamidopropyltrimethylammonium chloride. The system according to claim 1, which is an unsaturated monomer. 11. The solids content of the furnish is about 0.00
2. The composition of claim 1 further comprising a coagulant present in an amount from 5% to about 0.5% by weight.
The system described in 1. 12. The paper product manufactured with the fine particle system according to claim 1, wherein the acidic colloid is melamine-formaldehyde. 13. A paper product made with the fine particle system according to claim 2. 14. A process comprising: a) after the first high shear stage and before the second high shear stage, from about 0.0025% to about 0.0025% by weight based on dry weight of solids in the furnish. Adding a high molecular weight polymer flocculant to the lean stock flow of the furnish in an amount ranging up to 1.0% by weight;
And b) after the second high shear stage, removing the acidic colloid present in an amount ranging from about 0.0005% to about 0.5% by weight based on the dry weight of solids in the furnish. Adding to the furnish. A method for producing a paper product. 15. The process further comprising: c) prior to said first high shear stage, from about 0.005% to about 0.5% by weight based on dry weight of solids in the furnish. 15. The method according to claim 14, wherein the coagulant is added to the furnish in an amount. 16. The method according to claim 14, wherein the acidic colloid is melamine-formaldehyde. 17. The process comprising: a) after the first high shear stage and before the second high shear stage, from about 0.0005% to about 0.0005% by weight based on the dry weight of solids in the furnish. Adding an acidic colloid consisting of melamine formaldehyde present in an amount up to 0.5% by weight to the lean stock flow of the furnish, and b) after said second high shear stage, the furnish Adding to the furnish a high molecular weight polymeric flocculant in an amount ranging from about 0.0025% to about 1.0% by weight based on the dry weight of the solids therein. A method for producing a paper product, characterized in that: