JP2002526680A - Silica-acid colloid mixture in fine particle system used for papermaking - Google Patents

Abstract

A microparticle system for use as a retention and drainage aid in the production of alkaline and acid paper products comprises a high molecular weight flocculant polymer (6) and a silica-acid colloid blend (7), and optionally a cationic coagulant or a medium molecular weight flocculant (5). The high molecular weight flocculant polymer (6) may be added to the furnish after the fan pump (1) and prior to the pressure screen (2); the silica-acid colloid blend (7) may be added to the furnish after the pressure screen (2), and optionally, the coagulant or medium molecular weight flocculant (5) may be added prior to the fan pump (1). Addition of the microparticle system to the paper furnish improves retention and drainage during the papermaking process and sheet formation. The acid colloid of the silica-acid colloid blend (7) is a polymer or a copolymer of a melamine aldehyde acid colloid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] Background of the Invention 1. FIELD OF THE INVENTION The present invention relates to improved particulates having improved properties in the areas of retention, drainage, and sheet formability, for example, used as auxiliaries in forming paper products such as paper or paperboard. It is about the system. In particular, it relates to a particulate system containing a silica-acid colloid mixture as an inorganic particulate material in the particulate system.

[0002] 2. 2. Description of the Background Art In the production of paper or paperboard, a dilute aqueous composition known as "furnish" or "stock" is sprayed onto a moving mesh known as "wire". The solid components of the composition, such as cellulosic fibers and inorganic particulate filler material, are drained or filtered by a wire to form a paper sheet. The ratio of the solid material remaining on the wire is determined by the “first pass holding” (F
PR). Drainage, retention, and forming (D / R / F) aids are used in the papermaking process.

[0003] Retention has been thought to be due to the action of different mechanisms, such as mechanical entrainment, electrostatic attraction, and crosslinking between fibers and fillers in the furnish. Because both cellulosic fibers and many common filler materials are negatively charged, they repel each other. Generally, the only factor that tends to increase retention is mechanical entrainment. Thus, retention aids are used to improve retention of fibers and fillers on the wire. Retention of fines and fillers is important to the papermaker to establish retention of colloid-sized particles in the sheet. First pass hold (FPR) measures this capability of the hold program. Colloidal silica has been used in the past as fine particles in alkaline high quality paper retention aids. When used properly, silica can
Retention of fines and fillers can be increased to form fine flocs (microflocs) that trap the colloidal material, allowing rapid dewatering of the pulp slurry.

[0004] Drainage relates to the rate at which water is removed from the furnish as the paper sheet is formed. Drainage involves pressurizing the paper and removing the water that occurs prior to any pressing to form a sheet. Thus, drainage aids are used to improve the overall effect of dewatering in the manufacture of paper or paperboard.

[0005] Forming involves the formation of paper or paperboard sheets produced in the papermaking process. Molding is usually evaluated by the variation in light transmission into the paper sheet. High fluctuations indicate "poor" molding and low fluctuations usually indicate "good" molding. In general, as the retention level increases, the level of molding usually falls from good molding to poor molding.

[0006] Improvements in retention and drainage and in the forming properties of paper or paperboard sheets are particularly required for a variety of reasons, the most important of which has been recognized as productivity. . Good retention and good drainage allow the papermaking machine to run faster, reducing machine failure. Good sheet moldability
Reduce the amount of paper waste. These improvements are achieved through the use of retention and drainage aids. Retention and drainage aids are additives used to agglomerate finely divided solids present in furnish generally to improve these parameters in the papermaking process. The use of such additives is limited by the effect of agglomeration on the formability of the paper sheet. If more retention aid is added to increase the size of the agglomerates of finely divided solids, this generally results in fluctuations in the density of the paper sheet, and as described above, leads to `` bad '' sheet formation. May be the result. Over-coagulation can eventually lead to holes in the sheet, and can also have an effect on drainage, such as a loss of vacuum pressure in the later stages of dewatering during the subsequent papermaking process. Retention and drainage aids are generally added to the furnish at the wet end of the papermaking equipment, and are generally of three types: (a) a single polymer, (b) two polymers, or (c) ) There are particulate systems that can be used with flocculants and / or coagulants.

[0007] Particulate systems can generally yield the best results as retention and drainage aids and have been widely described in the prior art. Examples of particulate-based publications include: In EP-B-235,893, bentonite is used in the specified order of addition as the inorganic material associated with the HMW cationic polymer. WO-A-94 / 26972 discloses that a vinylamide polymer is used in combination with one of various inorganic materials such as silica, bentonite and china clay, and an organic material. WO-A-97 / 16598 discloses the use of kaolin in combination with one of various cationic polymers. In EPO805234, bentonite, silica, or an acrylic polymer is used in combination with a cationic dispersion polymer.

[0008] US Patent Nos. 4,305,781 and 4,753,710 disclose the use of HMW nonionic and ionic polymers combined with bentonite clay to promote dewatering and retention in papermaking. U.S. Patent Nos. 4,388,150 and 4,385,961 disclose the use of cationic starch and colloidal silica. U.S. Patent Nos. 4,643,801 and 4,750,974 disclose the use of cationic starch, anionic HMW polymers, and colloidal silica in papermaking. U.S. Pat. No. 5,185,062 describes anionic polymers that act as microparticles with HMW cationic flocculants. US Patent 5,167,
No. 766 teaches the use of charged organic polymer microbeads as fine particles in papermaking.

[0009] Melamine-formaldehyde (MF) acid colloids for the wet strength of paper are well known. "Wet Strength in Paper an" edited by CS Maxwell, JP Weidner
d Paperboard "TAPPI Monograph. U.S. Pat. No. 2,345,543 describes the preparation of stable melamine-formaldehyde acid colloids and U.S. Pat. No. 2,485,080 describes the inclusion of urea in condensation products. U.S. Patent Nos. 2,559,220 and 2,986,489 teach the use of these colloids to increase the wet strength of paper. U.S. Patent No. 4,845,148 discloses that to increase the dry strength of paper, No. 5,286,347 describes the use of melamine formaldehyde colloids for the control of resin content in papermaking US Pat.
No. 1,858 describes the use of a polyvinyl alcohol-melamine formaldehyde colloid mixture for wet strength of paper. U.S. Pat. No. 4,009,706 teaches the use of MF colloids and anionic HMW polymers to aggregate crude sugar. U.S. Pat. Is described.

[0010] Particulate systems generally contain a polymeric flocculant with or without a cationic coagulant and a fine particulate material. The fine particulate material may be an inorganic particulate material, which improves the effect of the flocculant and / or allows for the production of smaller and more uniform floc.

[0011] Certain end uses are used to achieve better operating properties of papermaking equipment and / or improved sheet formability for better printing properties, or improved surface strength, for example. The use of various particulate systems in paper mills to obtain paper properties is currently available, but due to drainage and retention during the papermaking process, as well as improved forming properties in the formed sheet, paper or paperboard. There remains a very real and practical need for improved particulate systems for the improvement of.

SUMMARY OF THE INVENTION The present invention meets this need. The present invention relates to particulate systems used as retention and drainage aids in papermaking processes.

According to a first aspect of the present invention, the addition of a particulate system as a retention and / or drainage aid having a polymeric polymeric flocculant and an inorganic particulate material to a paper stock or furnish is provided. Wherein the inorganic particulate material comprises a silica-acid colloid mixture, and the mixture further comprises colloidal silica and an acid colloid.

According to a second aspect of the present invention, there is provided an improved particulate system added to a paper stock or furnish as a retention and / or drainage aid, said particulate system comprising a high molecular weight polymer aggregate. Agent and an inorganic particulate material, wherein the inorganic particulate material comprises a silica-acid colloid mixture, and the mixture is a particulate system comprising colloidal silica and an acid colloid.

According to a third aspect of the present invention, there is provided a paper or paperboard having improved properties in the areas of retention, drainage and formability, wherein the paper or paperboard is an aqueous cellulosic paper stock or furnish. Prepared by adding an improved particulate system, said particulate system comprising a high molecular weight polymer flocculant and an inorganic particulate material including a silica-acid colloid mixture, and said mixture comprising colloidal silica and an acid colloid. Is included.

A fourth aspect of the present invention includes a method wherein the paper or paperboard is made by forming an aqueous cellulosic paper furnish, comprising: (a) after an initial shear stage, For thin stock flows of paper furnish,
Adding a high molecular weight polymer flocculant, (b) after the second shearing stage, adding to the paper furnish, an inorganic particulate material containing a colloidal silica and a silica-acid colloid mixture having an acid colloid. (C) draining the paper furnish to form the sheet, and (d) drying the sheet.

The acid colloid may comprise an aqueous solution of a water-soluble polymer which can be melamine aldehyde, urea aldehyde or melamine-urea aldehyde, wherein the aldehyde is represented by the following chemical formula:

[0018]

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Here, R ₁ is selected from the group consisting of linear and branched alkyl having 1 to 4 carbon atoms. The acid colloid is preferably a polymer of melamine formaldehyde, but is preferably a copolymer of melamine-formaldehyde and urea-formaldehyde, or a copolymer containing melamine aldehyde and condensates, or an amine-aldehyde type and ethylene-based copolymer. It may be a copolymer of saturated monomers.

In the silica-acid colloid mixture, the acid colloid and the colloidal silica are each about 99.000 based on total solids in an acidic environment of pH 3.0 or less.
It is mixed in a ratio within the range of 5: 0.5 to about 0.5: 99.5. The silica-acid colloid mixture has a composition of about 0.00% based on the dry solids weight in the furnish.
005% by weight to about 0.5% by weight.

[0021] The high molecular weight polymer flocculant is present in the furnish at about 0% based on dry solids weight.
. The silica-acid colloid mixture is present in the furnish in an amount of from about 0.0005% to about 0.5%, based on dry solids weight, in the furnish. Present in amounts within. A high charge density cationic coagulant, or a flocculant having a medium molecular weight, may be added to the furnish prior to the first shear stage, and in some instances, the addition of a silica-acid colloid mixture May be added before or after. In some instances, it may be more advantageous to change the order of the supply locations of the chemical additives in the papermaking equipment. That is, the silica-acid colloid mixture may be added to the stock or furnish prior to the first shear stage, or the coagulant or medium molecular weight flocculant may be added after or before the second shear stage, and The molecular weight flocculant may be after or before the second shear stage.

[0022] DETAILED DESCRIPTION OF THE INVENTION The present invention, in the papermaking process for the high-quality paper for both acid and alkaline,
It is directed to a particulate system that is used as a retention and / or drainage aid for certain applications in the wet end of papermaking equipment.

Here, the term “paper” includes products containing cellulosic sheet materials, including paper sheets, paperboard and the like.

The “fine particle system” of the present invention includes at least one kind of hydrophilic polymer used as an aggregating agent, an inorganic particulate material that is fine particles in the system, and, if necessary, a cationic coagulant or It is referred to as a combination of flocculants having a medium molecular weight. In the present invention, the inorganic particulate material is a silica-acid colloid mixture. The components of this combination may be added together to the stock or furnish being processed,
Preferably, they are separately added in the following manner or order.

The present invention can be implemented using a conventional papermaking device. According to conventional methods, the "thin stock" or furnish drained to form a paper sheet is treated in a mixing or closed vessel with pigment or filler materials, suitable fibers,
It is often made by diluting the thick stock typically produced by mixing any required reinforcing agents and / or other additives, and water, which may be circulated water. The thin stock can be cleaned by conventional methods such as, for example, a vortex washer. Usually, the thin stock is washed by passing through a centrifugal filtration membrane. The thin stock is pumped along the papermaking machine by one or more centrifugal pumps, commonly known as fan pumps. For example, a thin stock is pumped by a first fan pump to a centrifugal filtration membrane. The thick stock can be diluted with water to form a thin stock before the first fan pump or before the inlet site to the first fan pump, for example, where the thick stock and dilution water are combined. This is done by passing through a mixing pump. The thin stock may be further washed by passing through a second centrifugal filtration membrane and passed through a headbox prior to the sheet forming step of the papermaking machine.

The sheet forming step can be performed by using a conventional paper or board forming apparatus such as a flat wire fold liner, a twin wire former, or a bat former, or a combination of these forming apparatuses. An introduction system to a papermaking apparatus may include the elements shown in a single drawing. These elements include a fan pump 1, a pressure screen 2, and a headbox 3. The thick stock is passed through a mixing pump (not shown) of the thick stock and dilution water to form a thin stock, and the fan pump 1
May be diluted with water before the stock inlet. The thin stock is cleaned of impurities by flowing through the pressure screen 2 and the thin stock released from the pressure screen 2 flows to the headbox 3 before the sheet is formed.

[0027] The single figure also describes the preferred points of addition of the components of the particulate system of the present invention. Preferably, when a cationic coagulant or a medium molecular weight (MMW) flocculant is used, the thin stock is added to the thin stock before flowing through the fan pump 1 in the flow shown by arrow 4. . The addition is indicated by arrow 5. The high molecular weight (HMW) agglomerated polymer is added to the thin stock as it exits the fan pump 1, as shown by arrow 6. Also, the silica-acid colloid mixture is added to the thin stock as it exits the pressure screen 2, as indicated by arrow 7. Fan pump 1 and pressure screen 2 create a high shear stage in the papermaking equipment.

In the present invention, the HMW agglomerated polymer of the particulate system is preferably added before the thin stock arrives at the end of the high shear, so that the thin stock is, for example, at the last point of high shear And is suitably sheared. And it is preferably before the addition of the particulate silica-acid colloid mixture of the invention. In a single figure, the HMW flocculant is a thin stock with a pressure screen 2
, And the silica-acid colloid mixture is shown as being added after the stock has flowed through the pressure screen 2.

The HMW aggregated polymer of the particulate system of the present invention is preferably added to a thin stock (ie, desirably having less than 2%, at most 3% by weight solids) rather than a thick stock. . Thus, the HMW flocculant polymer may be charged directly into the thin stock or added to the dilution water used to convert the thick stock into a thin stock.

The HMW agglomerated polymer contains an agent for aggregating solids, especially fines, in the papermaking furnish. The term "fine powder" used here means TAPPI test method T
261 and T269 mean fine solid particles and fibers, respectively.

The agglomeration of the furnish fines may be effected by the HMW polymer itself, or by a combination with a high charge density cationic coagulant or MMW flocculant. Agglomeration of the fines provides better retention of the fines in the fibrous structure of the formed paper sheet, thereby improving dewatering or drainage.

The HMW flocculant is a polymer that provides a flocculating effect, preferably by itself.

An example of a preferred HMW flocculant polymer for use in the present invention is about 100,000
These have a weight average molecular weight of at least 500,000. Preferably, the weight average molecular weight is greater than one million, often greater than 5 million, and most typically ranges from 10 million to 30 million or more. These polymers may be linear, branched, cationic, anionic, nonionic, amphoteric, or hydrophobically modified acrylamide or other nonionic monomer Polymer.

[0034] The amount of particulate HMW flocculant added to the stock or furnish in the present invention provides substantial effectiveness against the agglomeration of solids, especially fines, present in the furnish. May be any amount sufficient to The total amount of water-soluble polymer added may range from about 0.0025% to about 1% by weight, more preferably 0.01% to 0.2%, and most preferably. , Approx.
It is in the range of from 0125% to about 0.1% by weight (dry weight of polymer based on the weight of dry solids present in the furnish). The addition may be performed in one or more dosing locations at one or more dosing locations, preferably in one dosing for thin stock flows after a fan pump that causes high shear. It is.

Desirably, flocculent (flock) formed by HMW polymer flocculant
Is subjected to a shearing action prior to the addition of the particulate silica-acid colloid mixture of the present invention. Preferably, this shearing action is caused by a pressure screen that causes high shearing action.

[0036] In a preferred embodiment, the particulate particulate material of the present invention is described in US Pat.
No. 382,378, including silica-acid colloid mixtures, such as those compositions disclosed therein, the teachings of which are incorporated herein by reference. For example, a mixture of melamine aldehyde, urea aldehyde, or melamine urea aldehyde, and colloidal silica is included in the silica-acid colloid mixture of the present invention. As described in U.S. Pat. No. 5,382,378, silica sol is a dispersion of discrete colloidal particles of amorphous silica stably dispersed in an aqueous solution. The silica sol is in the range of 5 to 50% SiO ₂ ,
And has a particle size of less than 1 micron. The stability of the silica sol depends on maintaining a high electrostatic repulsion between the silica particles. The pH is made alkaline to maintain a negative charge on the silica particles to prevent aggregation. Colloidal solutions have very poor stability at low pH and tend to gel.

Preferred silica sols for use in the present invention are those having a particle size of less than 1 micron, preferably 3 to 20 nm, and having a solids content of 0.5% to 50% by weight.

In a preferred embodiment, any melamine aldehyde type polymer can be used as the acid colloid component of the fine particles. The polymer is prepared by using a) melamine or a substituted melamine, and b) an aldehyde having the formula:

[0039]

Embedded image

Here, R ₁ is selected from the group consisting of linear or branched alkyl groups having 1 to 4 carbon atoms. Dialdehyde can also be used. The dialdehyde may be linear or cyclic having 2 to 8 carbon atoms and may be C-substituted and contain heteroatoms. Preferred aldehydes are methanal (formaldehyde), ethanal, propanal, glyoxal, and glutaraldehyde. The most preferred aldehyde is formaldehyde.

The molar ratio of components a) and b) above ranges from about 1: 1 to 1:10, and more preferably ranges from about 1: 3 to about 1: 6. The most preferred molar ratio is about 3 moles of aldehyde to about 1 mole of melamine or a derivative thereof.
Thus, the most preferred polymers are prepared from melamine and formaldehyde, with a molar ratio of melamine to formaldehyde of about 1: 3.

The melamine aldehyde type polymer of the present invention is insoluble in water, but can be maintained in a colloidal suspension in an acidic solution. Although hydrochloric acid is preferred, any acid or compatible combination of acids can be used to prepare the melamine aldehyde acid colloid of the particulate particulate material of the present invention. The active ingredient of the melamine aldehyde-type polymer in the acidic suspension or solution is about 0.1% to about 20%, preferably 1% to about 15%, most preferably about 4% to about 12%.
%. The pH should be low enough between 1.0 and 2.5 with an aqueous inorganic or organic acid to keep the melamine aldehyde type polymer in a fine colloidal suspension.

Suitable urea aldehyde type polymer solutions for use in the present invention are those wherein the aldehyde is as defined above, and most preferably a urea-formaldehyde solution. The molar ratio of urea to aldehyde ranges from 1: 1 to 1:10, with the most preferred ratio being from 1: 3 to 1: 6.

[0044] Melamine urea aldehyde copolymer solutions can also be employed in the present invention. These solutions are prepared from an aldehyde component, urea, and melamine or a substituted melamine as defined above. Preferably, it is a melamine-urea-formaldehyde copolymer solution. Melamine-urea-formaldehyde copolymer solutions suitable for use in the present invention comprise 1 to 70 mole% urea, 30 to 99 mole% melamine, and each mole of melamine and urea combined in an acidic aqueous medium. From about 1 to 4 moles of aldehyde. The copolymer solution used in the present invention ranges from 0.1 to 20 percent solids, preferably from 1 to 12 percent solids.

The acid colloid may be a copolymer containing melamine aldehyde and condensates including ammeline-aldehyde, dicyandiamide aldehyde, diguanidine-aldehyde, urea formaldehyde polyalkylene polyamide, and polyureide.

The acid colloid is prepared by reacting a specific aldehyde with an amine, and aging the solution under acidic conditions, typically using hydrochloric acid. As ripening proceeds, 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. That is, some of the secondary amine units are protonated. The colloidal solution shows a characteristic blue haze. Solution is 8-12%
Preserved in activity. The solution may consist mostly of amines and aldehydes,
Alternatively, a derivative thereof may be used. The solution may be partially etherified with an alcohol, glycol or other hydroxyl containing species. The solution may be a co-condensation of melamine formaldehyde and another amino resin, and may be etherified. The solution may be a mixture of such amino resins, which is used to form an acid colloid. The colloid-forming amino resin may be a copolymer of an ethylenically unsaturated monomer, such as acrylamide, dimethylaminoethyl acrylate, diallyldimethylammonium chloride (DADMAC), or methacrylamidopropyl trimethylammonium chloride. .

In a preferred embodiment, the composition of the microparticles of the invention is similar to and is prepared similarly to that disclosed in US Pat. No. 5,382,378, which is hereby incorporated by reference. The pH of the colloidal silica solution is first reduced to between 1.3 and 2.0 using 10% hydrochloric acid. For example, an acid colloid solution, which is a melamine urea aldehyde copolymer, is added during stirring. The resulting mixture has a pH of about 1.0 to 3.0, preferably a pH of 1.5. The mixture can be between 1.0 and 50% total solids. In the present invention,
These silica-acid colloid mixtures are applied as part of a particulate system within a retention, drainage, and sheet forming program for forming paper or paperboard.

The amount of silica-acid colloid of the particulate particulate material of the particulate system of the present invention added to the paper or furnish may be about 0% by dry weight, based on the weight of dry solids in the furnish. It can be in the range between 0.0005% to about 0.5%, preferably between about 0.005% to about 0.25% by weight. The addition can take place in one or more doses at one or more locations, but is preferably in a single dose, preferably after pressure screen 2 in a single figure, and 2 and the headbox 3.

The silica-acid colloid mixture in the fine particle system of the present invention comprises colloidal silica,
And acid colloids, preferably melamine formaldehyde acid colloids and derivatives thereof as described above.

In general, the addition of the HMW flocculant polymer causes the formation of large, solid, flocculent (flock) suspended in the paper or furnish to which the polymer is added. These large flocs (flocks) are immediately or subsequently broken by high shear into very small flocs known in the art as "microflocs". This “high shear” may be introduced by the flow of the floc-formed furnish through the pressure screen 2 in a single drawing.

The water-soluble coagulant is generally of lower molecular weight than the HMW flocculant added to the stock in front of the pressure screen 2, and preferably is a stock prior to the stock flowing through the fan pump 1 in a single drawing Is added to The coagulant is preferably a high charge density cationic polymer. For example, if the coagulant polymer is a nitrogen-containing cationic polymer, it may have a charge density of about 0.2, preferably at least 0.35, most preferably 0.4 to 2.5 or more. And is equivalent to nitrogen per kilogram of polymer. If the polymer is formed by polymerization of a cationic ethylenically unsaturated monomer, optionally with other monomers, the amount of cationic monomer will be based on the total amount of monomers used in forming the polymer. It is generally about 2 mol%, and usually about 5 mol%, and preferably at least about 10 mol%.

Suitable cationic coagulants include the following: Polydiallyldimethylammonium chloride (p-DADMAC); polyalkylamines; dimethylamine and / or cationic polymers of ammonia or other primary and secondary amines with epichlorohydrin; polyamidoamines Kinds; DADMAC
Or copolymers of a cationic monomer such as acryloyloxyethyltrimethylammonium chloride with a nonionic monomer such as acrylamide; cyanoguanidine-modified polymers of urea / formaldehyde resins; polymers of melamine / formaldehyde; Polymers of / formaldehyde; polyethylene imines; cationic starches; cationic aluminum salts singly and in polymers; amphoteric polymers which process an effective cationic charge; and mixtures of the abovementioned coagulants.

The amount of cationic coagulant in the particulate system of the present invention added to the stock or furnish has a substantial effectiveness in coagulating the solids present in the paper or furnish. Any amount may be used as long as it is sufficient to give
The total amount of water-soluble coagulant polymer can be in the range of about 0.0025 to 1.0% by dry weight, based on the weight of dry solids present in the furnish, more preferably Is in the range of about 0.005% to about 0.50% by weight.

If an MMW flocculant is used instead of the cationic coagulant, this flocculant can be added before the stock passes through the fan pump 1. Examples of suitable MMW flocculants for use in the present invention are those having a weight average molecular weight in the range of 500,000 to about 5 and 6 million. The chemical additive may be acrylamide or a copolymer of any unsaturated monomer. Suitable MMW flocculant Calgon Corporation, ECCat ^TM 50 that available husband from PA
It may contain a 0 copolymer.

[0055] The amount of MMW flocculant can be any amount sufficient to provide substantial effectiveness in coagulating the solids present in the paper or furnish. Good. The total amount of MMW flocculant may range from about 0.0025 to 1.0% by weight, based on the weight of dry solids present in the furnish. Dosages are in the range of 0.01 to 0.5 lb / ton polymer.

As mentioned above, the cationic coagulant or MMW flocculant can be added to the thick stock before the fan pump, and the HMW flocculant is thinner after the stock passes through the fan pump 1. It may be added to stock. Then, the silica-acid colloid mixture of the present invention may be added to the thin stock after the stock has passed through the pressure screen 2 in the single figure. Alternatively, these chemical additives may be added to the stock in a different order than shown in the figure. That is, the silica-acid colloid mixture may be added before the fan pump 1 and the HM
W coagulant may be added after pressure screen 2 and coagulant or MMW coagulant may be added before pressure screen 2. In the papermaking apparatus, the supply points for the chemical additives may be in another order.

The initial thick stock may be, for example, a traditional chemical pulp such as bleached or unbleached sulfate or sulfite pulp; a mechanical pulp such as groundwood pulp; a thermomechanical pulp; or a chemical thermomechanical. Pulp; regenerated pulp such as fiber filler composites from the agglomeration or recycling process, deinked waste; and mixtures thereof, such as those made from any conventional papermaking stock.

The furnish or stock used in the present invention and the final paper may be substantially unfilled (eg, less than 10% by weight in the final paper, typically 5%). Less than 10% by weight of filler).
The final stock may be filled with fillers that can be supplied in amounts up to 50% based on dry solids weight, or up to 40% based on dry weight of the paper. If a filler is used, any conventionally used white pigment filler may be present, for example, calcium carbonate, kaolin clay, baked kaolin, titanium oxide, or talc, or mixtures thereof. Fillers, if present, are preferably included in the furnish by conventional methods and prior to the addition of the particulate system components of the present invention.

The final stock or stock used in the present invention may contain other known optional additives such as rosin, alum neutral size or optical brighteners. . It may include fortifying agents, or binders, in which case it may include starch, for example, cationic starch. The furnish pH is generally in the range of about 4 to about 9.

The amounts of fibers, fillers, and other additives, eg, fortifying agents, or alum, can all be conventional. Typically, thin stocks have between 0.1% and 3% solids by weight, or 0.1% by weight.
To 2% by weight of the fiber component. Thin stocks will usually have from 0.1% to 2% solids by weight. These ratios are based on the dry solids weight in the furnish.

As mentioned above, the silica-acid colloid mixture used as the particulate particulate material in the particulate system of the present invention is colloidal silica and an acid colloid or a derivative thereof. The acid colloid is preferably composed of an aqueous solution of a water-soluble polymer, which is preferably melamine aldehyde, more preferably melamine-formaldehyde. This particulate material is easily dispersed in an aqueous pulp suspension in the papermaking process to improve the surface properties of the final paper product.

The present inventors have found that a silica-acid colloid mixture bound by the HMW coagulant itself, or with the coagulant, or with the MMW coagulant, can increase drainage and retention, and increase the sheet in the papermaking process. It has been found that the moldability can be improved.

[0063] The following examples are intended to illustrate the invention in more detail, it is not intended to limit the scope of the present invention in any case. The following products were used in these experiments.

Polymer A: 25% by weight active acrylamide having about 90 mole% acrylamide and about 10 mole% acryloyloxyethyltrimethyl-ammonium chloride, available from Calgon Corporation (Pittsburgh, PA) -Acryloyloxyethyltrimethylammonium chloride copolymer.

Polymer B: having about 70 mole% acrylamide and about 30 mole% acrylic acid, available from Calgon Corporation (Pittsburgh, PA)
Anionic flocculant-28% by weight active anionic acrylamide-acrylic acid copolymer.

Polymer C: Medium molecular weight cationic copolymer of acrylamide and diallyldimethylammonium chloride, available from Calgon Corporation (Pittsburgh, PA).

Polymer D: Medium molecular weight terpolymer of acrylamide, diallyldimethylammonium chloride, and acrylic acid, available from Calgon Corporation, Pittsburgh, PA.

Melamine-formaldehyde (MF) acid colloid: 8% active solution available from Calgon Corporation, Pittsburgh, PA.

Colloidal silica: available from Dupont (Wilmington, DE)
15% active solution.

Carbital 60: A dry, ground calcium carbonate available from ECC International Inc. (Atlanta, GA).

Staroc ^™ 400 (Federal Trademark of AE Staley) and Interbond C: Cationic starch available from AE Staley.

Harcon 70: AKD (alkyl ketone dimer) size available from Hercules, Inc.

EXPERIMENTAL EXAMPLES 1-16 Preparation of Alkaline Fine Paper Furnish Preparation of Synthetic Alkaline Fine Paper Furnish was prepared, used for drainage and retention tests, and handsheets were formed. . This furnish was prepared with the following ingredients.

Fiber: 50/50% by weight, bleached hardwood kraft / bleached softwood kraft Filler: 50/50% by weight, ground calcium carbonate (Carvital 60)
/ Precipitated calcium carbonate Filler loading: 20% by weight based on fiber solids Starch: 0.5% by weight based on fiber solids (Interbond C) Size: 0.25% by weight HARCON 70 (AKD)

The dried wrapped pulp is soaked in lukewarm water for 10 minutes, diluted with water to a concentration of 2% solids by weight, and digested with a laboratory-scale Voice Alice Valley beater to 590 ml of Canadian Standard Water (CSF) And purified. The starch, size, and filler were added into the washed pulp slurry in this order. The pH of the pulp slurry was typically 7.5 ± 0.3. The pulp slurry was further diluted with tap water to a concentration of about 1.0% by weight to form a thin stock for drainage and retention tests, and a handsheet was formed. This furnish is representative of the typical alkaline good paper furnish used to form printing and writing grade paper.

Drainage Test Procedure 200 ml (2 g solids) of furnish at a headbox concentration of 1.1% by weight was poured into a rectangular mixing jar and diluted with 500 ml of tap water.

[0077] 2. These components are contained in a standard Brit Jar propeller mixer (diameter 1).
Inches). The mixing is performed according to the following mixing time (second) and speed (
(rpm), the addition of the chemical additive was simulated at the second fan pump inlet, fan pump outlet, and pressure screen outlet.

[0078]

[Table 1]

[0079] 3. The components in the mixing jar were transferred to a 500 ml graduated drain tube fitted with a 100 mesh screen at the bottom. The tube was inverted five times to ensure that the stock was homogeneous. The bottom stopper of the tube was removed and the elution times at 100, 200 and 300 ml elution volumes were measured. The elution time in a 300 ml volume of untreated stock blank should preferably be longer than 60 seconds.

[0080] 4. The improvement in wastewater provided by the treatment was calculated as follows, based on the drainage time of the untreated blank sample.

[0081]

(Equation 1)

Retention test procedure (FPR, FPAR) TAPPI test method T269 1. While stirring the stock at 1200 rpm, the head box concentration (1.0
%) Of the furnish was poured into a brit jar having a 70 mesh screen.

2. The order of mixing time (seconds) / speed (rpm) was similar to that used in the drainage test procedure above to simulate the chemical addition points, except for the following changes.

[0084] In t _30, the bottom stopcock is opened for the first 100ml were collected eluted.

[0085] 3. The eluate was filtered through Whatman No. 4 filter paper,
Dried at 05 ° C.

[0086] 4. The pad was burned at 600 ° C. for 2 hours and ash retention was determined.

Handsheet Preparation and Testing Handsheets were prepared with a nominal weight of 70 grams / square meter used in Novell and Wood handsheet molds. This device is 20cm x 2
Form a 0 cm square handsheet. The mixing time / speed sequence used to form the handsheets was the same as that used for the drain test procedure. Samples of the treated furnish were poured into the deckle box of a Novell and Wood handsheet machine, and the sheets were prepared using standard techniques well known to those skilled in the art.

Sheet Properties Molding was tested on handsheets using the MK System Molding Tester, Model M / K950R. Brightness and opacity measurements were made using a Technidyne Color Touch, Model ISO.

Preparation of Mixture The colloidal silica-acid colloid mixture was prepared by the following procedure.

1) The amounts of colloidal silica solids and acid colloid solids in the ratios in Table 1 were calculated, and the specified amounts of each solution were added in separate beakers.

2) A pH probe attached to a pH meter was placed in the colloidal silica solution. The pH of this solution was reduced to about 1.5 by adding 10% hydrochloric acid.

[0092] 3) The acid colloid solution was added to the colloidal silica solution while stirring the colloidal silica solution.

4) The pH of the final mixture of 3) above was adjusted to 1.5 by adding 10% hydrochloric acid.
Was adjusted to

Table 1 summarizes the composition ratio of the silica-melamine formaldehyde (MF) mixture used in Experimental Examples 1 to 16.

[0095]

[Table 2]

Experimental Examples 1 to 7 Table 2 shows the results of drainage in Experimental Examples 1 to 7, and Table 3 shows the same results as in Experimental Examples 1 to 7
Shows the results of the retention of. Experimental Examples 2 and 4 show the effectiveness especially when using a silica-MF mixing ratio of 4: 1.

Drainage: The doses in Examples 1-7 are shown as activity based on pounds / ton of dry pulp. The data shown in Table 2 shows the effectiveness of a 4: 1 silica-MF mixing ratio for increasing furnish dewatering rates. As shown in Experimental Example 2, 4:
Using a mixing ratio of 1 at 1.0 pounds / ton increases wastewater. That is, it is shown that the drainage speed of Experimental Example 2 using the silica-MF mixing ratio of 4: 1 increases as compared with Experimental Example 1. That is, the drainage speed of Experimental Example 1 is 39%, while the drainage speed of Experimental Example 2 is 57%. Further improvements in administration with a 4: 1 mixing ratio of silica-MF with even better drainage can be seen in Examples 3 and 4 in Table 2. That is, in Experimental Example 3, it is 63%, while in Experimental Example 4, it is 68%.

A silica-MF mixing ratio of 4: 1 (Example 4) also added less starch at a similar dose of 2.0 lb / ton, ie furnish at the inlet of the fan pump. At this point, in comparison with Experiment 7 at 15 lb / ton, Example 4 was even more effective at 5 lb / ton starch than at the silica itself (Example 7). there were. This is important because reducing the amount of starch required in a papermaking system allows the papermaker to reduce costs.

[0099]

[Table 3]

Retention: Table 3 shows the 4: 1 silica-MF mixing ratio of the present invention to increase first pass retention (FPR) and first pass ash retention (FRAR) in the drain / retention / formation program. Show ability. Retention is performed in the mixing order described above, using the brit method (TAPPI
It was measured using the test method T269). Experimental Example 1, which did not include the particulate material,
The FPR was 5.2%. When silica / MF mixing ratio of 4: 1 was added at 2 lb / ton, as shown in Experimental Example 4, FPR increased to 92.0% and FPAR increased to 61%.
% (Experimental Example 1) to 80.1% (Experimental Example 4). FPR and FP
This increase in AR results in a more efficient papermaking process, reduced use of fillers,
And it is an important factor for paper makers in that sheet properties are improved. The silica-MF mixture ratio of 4: 1 of the present invention also allows the use of lower amounts of starch to achieve similar retention results as those examples using silica alone. That is, Experimental Example 3 (4: 1 mixture) in comparison with Experimental Example 6 (silica).

[0101]

[Table 4]

Experimental Examples 8 to 12 1: 1 mixture Table 4 shows the results of drainage of Experimental Examples 8 to 12, and Table 5 shows the results of retention of Experimental Examples 8 to 12. These results show the effectiveness in increasing drainage and retention as the dose of the 1: 1 silica-MF mixture in Table 1 was increased from 1.0 lb / ton to 2.0 lb / ton. Things. Similar to a 4: 1 silica-MF mixing ratio, this 1: 1 mixture shows similar performance to silica, but at lower starch levels, ie, 15 lb / ton for silica. At 5 lbs / ton.

[0103]

[Table 5]

[0104]

[Table 6]

Experimental Examples 13 to 16: 1: 4 mixture Table 6 shows the results of drainage of Experimental Examples 13 to 16, and Table 7 shows the results of retention. These results show that drainage and retention are improved when a 1: 4 ratio of the silica-MF mixture in Table 1 is added to the DRF program. Tables 6 and 7
As can be seen in Example 1, drainage and retention were improved in Examples 14-16 when the silica-MF mixing ratio of the present invention was 1: 4, i.e., as compared to Example 13 where no mixture was used. Have been.

[0106]

[Table 7]

[0107]

[Table 8]

Mixture Stability As shown in Table 8, different ratios of the silica-MF mixture were pH dependent, depending on the composition.
= 2.0 with different stability. The following measurements were made.

[0109]

[Table 9]

As the silica-MF mixing ratio of 1: 4 shows, the more acid colloid present in the mixture, the longer it is stable at acidic pH, ie more than 180 days. 12% MF was formed by concentrating the solution at 8% total solids. The mixtures according to the invention have considerably better stability than any of the separate components. That is, 15 and 90 days compared to 150 or more days for the silica-acid colloid mixture of the present invention.

Experimental Examples 17-21: The remainder of the Lightweight Coated (LWC) furnish experimental example was used at a total solids of 15% and a silica-MF mixture ratio of 9: 1 (weight / weight, solids). . The silica used was DuPont (Wilmington, D.C.).
30% solids silica available from E). The mixture was prepared according to the method described above.

Examples 17-21 in Tables 9-A and 9-B demonstrate the effectiveness of the present invention in improving drainage, retention, and sheet formability in synthetic aqueous furnishes. This furnish is representative of the typical furnish used to produce lightweight coated paper (lightweight coated) grade substrate sheets. The furnish was treated with 15 lb / ton Stalok 400 starch for 15 minutes before the retention aid was added.

Preparation of furnish: The synthetic furnish used for drainage and retention tests and for handsheet formation was prepared with the following ingredients.

Fiber: 45% by weight bleached softwood kraft (SWK) 55% by weight chemishermomechanical pulp (CTWP) Filler: baked clay Filler loading: 10% by weight based on total dry fiber weight Alum: total dry 0.5% by weight based on fiber weight

In preparing the furnish, the CTMP was immersed in hot water for 15 to 20 minutes, diluted with water to 1.5% solids by weight, and 200 ml of Canadian standard filtered water (C
Until SF), this was solved or refined in a laboratory-scale Voice Alice Valley beater. SWK was separately immersed in water, diluted to 1.5% solids by weight, digested and purified to 550 ml CFW. The fibers were mixed in the ratios described above and baked clay was added. The pH of the furnish was adjusted to 5.0 with dilute sulfuric acid and the conductivity was 2000 μS / cm with sodium sulfate.
Was adjusted to

[0116]

[Table 10]

[0117]

[Table 11]

Experimental Examples 18-21, shown in Tables 9-A and 9-B, illustrate the effect of adding the fine particle mixture to the LWC furnish at a location after the screen. Increasing the addition of the particulate mixture results in a sharp increase in drainage, FPR, and FPAR. Compared to sheets not treated with the particulate system of the present invention, the furnish filler and fines are more retained while the sheets can be dried faster and the papermaker can These effects are important because speed can be increased. The results in Tables 9-A and 9-B show that the brightness and opacity of the sheet remain relatively unchanged, while simultaneously forming the sheet, as compared to the sheet that was not treated with the particulate system of the present invention. Shows that the sex is reduced using the present invention.

Experimental Examples 22-26: Paperboard furnishes Experimental examples 22-26 in Tables 10-A and 10-B show synthetic aqueous furnish drainage,
It illustrates the effectiveness of the present invention in maintaining and improving sheet properties. This furnish is representative of typical furnishes used to form substrate sheets for paperboard.

Preparation of furnish: Furnish is prepared by dissolving 360 g of unbleached old cardboard (OCC) in lukewarm water and diluting to 23 liters with tap water. The pulp was then refined by a laboratory scale beater to 300 ml of CSF as in previous experimental examples. 18 liters of this stock was diluted to 0.5% by weight and the following salts were added to adjust the water chemistry to paper mill conditions. That is, 5
. 61 g calcium chloride, 0.96 g potassium chloride, 8.17 g alum (50% by weight), 15.96 g sodium sulfate, 0.59 g sodium bicarbonate, and 0.97 g sodium silicate. Conductivity is about 2000μS
/ Cm. The pH was adjusted to 5.0 with dilute sulfuric acid.

[0121]

[Table 12]

[0122]

[Table 13]

In Tables 10-A and 10-B, Examples 22, 25, and 26 demonstrate the effect of using 20 pounds of starch in paperboard furnish in connection with the particulate mixture of the present invention. It is. Also, Tables 10-A and 10-B show that increasing doses of the particulate mixture and starch of the present invention show that drainage, FPR, and FPAR
It indicates that is increased. These results also show that the particulate mixture also performs well when 10 pounds of starch is used in the furnish. This is believed to indicate that in some furnishes, the high concentrations required of starch to be effective are not required by the present invention. Conventional silica programs generally require high doses of starch to achieve efficacy, but this is not the case when using the microparticle system of the present invention.

Experimental Examples 27-30: Furnish for Newsprint Paper Examples 27-30 of Tables 11-A, 11-B, and 11-C show the drainage, retention, and sheet forming of synthetic aqueous furnishes. This shows the effectiveness of the present invention in improving the properties. This furnish represents a typical groundwood pulp furnish used to make base sheets for newsprint.

Preparation of furnish: A synthetic furnish used for drainage and retention tests and used to form a handsheet was prepared as follows.

Fiber: 80% by weight CTMP 10% by weight SWK 10% by weight Renewed newsprint Filler: baked clay Filler loading: 4% by weight based on total dry fiber weight Alum: 50 lb / ton

In this furnish preparation, the CTMP is immersed in hot water (140 ° F.) and loosened in a blender for 15 to 20 minutes. Recycled newsprint is separately processed in a similar manner. The SKW is immersed in lukewarm water for 2 hours and loosened in a blender for 15 to 20 minutes.

CTMP, recycled newsprint, and SKW were mixed together and from 50 to 75 ml of CSF with a laboratory scale beater as in the above experimental example.
Purified at a concentration of 5% by weight. Baked clay and alum have a final pH of 4.
8 to 5.2. The conductivity of the stock is adjusted to 2000 μS / cm using sodium chloride.

[0129]

[Table 14]

[0130]

[Table 15]

[0131]

[Table 16]

In Tables 11-A to 11-C, Experimental Examples 27 and 28 show that when the particulate mixture of the present invention was added to newsprint furnish at a position after the screen,
Shows that increases in drainage, FPR, and FPAR are seen. Drainage, FP
This increase in R, and FPAR will be an important consideration in high speed newsprint equipment. These results of Experimental Examples 27 and 28 also show that the particulate system of the present invention is effective even without starch. These factors allow the paper manufacturer to reduce costs, thereby lowering the total cost per ton of paper produced.

Application to Commercially Available Machines Good Quality Alkaline Paper The effect of the present invention was evaluated on a commercially available good quality alkaline paper machine. The microparticle mixture program of the present invention was compared to a basic (baseline) program. The basic (baseline) program is that polymer B is fed in front of the screen (0.15 lb / ton active) and polymer C is fed to the post-screen furnish (1.0 lb / ton active). As performed on the device. In the particulate program of the present invention, polymer C was fed to the furnish at a pre-screen stage, and the particulate mixture was added at a post-screen stage (1.0 lb activity). Note that dosages are approximations and have been altered by differences in underlying weight and paper grade. The program of the present invention was also compared to a representative silica program. Here, in the silica program, polyamine is supplied to the tray (1.5 lb / ton activity), HMW anionic polyacrylamide is supplied to the stage before the screen (1.0 lb / ton activity), and colloidal silica is supplied. Added to post-screen stage (1.5 lb / ton activity). The results of this comparison are shown in Tables 12 and 13.

[0134]

[Table 17]

[0135]

[Table 18]

From Table 12 (80 pounds, basis weight), it can be seen that the particulate mixture of the present invention has improved sheet formability (lower numbers are better), lower flow usage, and more compared to other programs. You can see the result of high press solids. In the use of equivalent streams, the present invention is more efficient than a basic (baseline) program.
The equipment speed increased by 3.6%, and 3.1% over the conventional silica program. This factor can allow the papermaker to increase the speed of the equipment, resulting in more paper production and / or lower energy to create a stream. These results also show better sheet formability when the microparticle mixture of the present invention is used. This factor is important in that more uniform and higher quality paper sheets can be produced.

Table 13 (100 pounds, basis weight) shows that for a 100 pound basis weight paper,
4 shows a comparison between the use of the microparticle mixture of the invention and the use of other programs. Drainage is an important issue in heavier weight papers and in thicker sheets where more energy is required for drying. The present invention is shown as providing better sheet formability, higher pressed solids, and lower flow when compared to the base (baseline program) or silica program. These factors of the present invention enable papermakers to produce higher quality sheets at higher papermaking machine speeds.

While specific embodiments of the present invention have been described by way of illustration, various modifications and details of the invention may be made without departing from the invention as defined in the appended claims. What we do is obvious to those skilled in the art.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The single drawing schematically depicts parts of a typical papermaking machine and points of addition of the components of the particulate system of the invention in a preferred form.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) D21H 21/06 D21H 21/06 (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, E E, 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, ZWF terms (reference) 4D015 BA09 BA11 BA19 BB09 BB14 CA20 DA35 DB07 DB09 DB26 DB33 DC07 EA04 EA35 4L055 AG18 AG80 AG81 AH18 EA32 FA20 FA22 GA05 GA16

Claims (21)

[Claims] 1. A particulate system used as a retention and drainage aid in a paper furnish comprising: a) from about 0.0025% to about 1.0% based on dry solids weight in said furnish.
B. A HMW polymer flocculant present in an amount of: b) a silica-acid colloid mixture comprising: (1) an acid colloid comprising an aqueous solution of a water-soluble polymer or copolymer; and (2) a colloidal silica; An acid colloid and said colloidal silica comprise a silica-acid colloid mixture which is mixed in a range of 99.5: 0.5 to 0.5: 99.5, respectively, based on total solids under acid conditions of pH 3.0 or less; A particulate system wherein the silica-acid colloid mixture is present in the furnish in an amount from about 0.0005% to about 0.5% by weight, based on dry solids weight. 2. The microparticle system according to claim 1, wherein the polymer is selected from the group consisting of substituted or unsubstituted melamine and melamine aldehydes of the formula: Embedded image (In the formula, R1 is selected from the group consisting of a linear or branched alkyl group having 1 to 4 carbon atoms.) 3. The particulate system according to claim 2, wherein said aldehyde is an aldehyde selected from the group consisting of formaldehyde, ethanal, propanal, glyoxal, and glutaraldehyde. 4. The particulate system according to claim 3, wherein said aldehyde is formaldehyde. 5. The particulate system according to claim 4, wherein said water-soluble polymer is melamine-formaldehyde. 6. The fine particle system according to claim 5, wherein the melamine-formaldehyde is etherified with a linear or branched alcohol. 7. The microparticle system according to claim 1, wherein the silica-acid colloid mixture comprises colloidal silica and an acid colloid of a copolymer of melamine-formaldehyde and urea-formaldehyde. 8. The condensation wherein the silica-acid colloid mixture is selected from the group consisting of the colloidal silica and the melamine aldehyde and amelin-aldehyde, dicyandiamide aldehyde, biguanidine-aldehyde, urea formaldehyde polyalkylene polyamine, and polyureide. 2. The fine particle system according to claim 1, further comprising an acid colloid of a copolymer containing substances. 9. The silica-acid colloid mixture wherein the colloidal silica and an ethylenically unsaturated monomer selected from the group consisting of acrylamide, dimethylaminoethyl acrylate, diallyldimethylammonium chloride, and methacrylamidopropyl trimethylammonium chloride 2. The fine particle system according to claim 1, comprising an acid colloid of an amine-aldehyde type copolymer. 10. The composition of claim 1 wherein said furnish comprises about 0.00
The particulate system of claim 1, further comprising a high charge density or thionic coagulant present in an amount from 5% to about 0.5% by weight. 11. In the furnish, based on the dry solids weight, about 0.00
2. The particulate system of claim 1, further comprising a medium molecular weight flocculant present in an amount from 25% to 1.0% by weight. 12. A paper product formed using the particulate system according to claim 1. 13. A paper product formed using the particulate system according to claim 2. 14. A process for the production of paper products, comprising: a) after the first high shear stage and before the second high shear stage, based on the dry weight of solids in the paper furnish. Adding a high molecular weight polymeric flocculant to the furnish in an amount from about 0.0025% to about 1.0% by weight; and b) before or after the second high shear stage, Adding a silica-acid colloid mixture to the paper furnish in an amount of from about 0.0005% to about 0.5% by weight, based on dry weight of solids, of the paper product. C) prior to said first high shear stage, a high charge density cationic of from about 0.005% to about 0.5% by weight based on the dry weight of solids in said furnish; The method of claim 14, further comprising: adding a coagulant to the furnish. 16. The method of claim 14, wherein said silica-acid colloid mixture comprises a melamine-formaldehyde acid colloid. 17. c) Prior to the first high shear stage, a medium molecular weight polymer in an amount from about 0.025% to about 1.0% by weight based on the dry weight of solids in the furnish. The method of claim 14, further comprising adding to the furnish. 18. A process for producing a paper product, comprising: a) after the first high shear stage and before the second high shear stage, based on the dry weight of solids in the furnish, Adding a silica-acid colloid mixture to the paper furnish such that it is present in an amount of 0.0005% to about 0.5% by weight; and b) before or after said second high shear stage. A process for producing a paper product comprising the step of adding from about 0.0025% to about 1.0% by weight, based on the dry weight of solids in the stock, of a high molecular weight polymer flocculant to said paper furnish. C) prior to said first high shear stage, a high charge density cationic of from about 0.005% to about 0.5% by weight based on the dry weight of solids in said furnish; 19. The method of claim 18, further comprising: adding a coagulant to the furnish. 20. The method of claim 18, wherein the silica-acid colloid mixture comprises a melamine-formaldehyde acid colloid. 21. c) Prior to the first high shear stage, a medium molecular weight polymer in an amount of from about 0.025% to about 1.0% by weight based on the dry weight of solids in the furnish. 19. The method of claim 18, further comprising: adding to the furnish.