KR100580306B1 - Selective retention of filling components and improved control of sheet properties by enhancing additive pretreatment - Google Patents

Abstract

The present invention relates to a method for increasing the retention and drainage levels of filler components in paper making furnish used in the papermaking process. The method includes preparing a slurry of filler component; Treating the slurry with 0.003% to 2.0% by weight of a phenolic enhancer based on the total solid weight of the paper stock to form a pretreated filler component slurry; Adding the pretreated slurry to the paper stock; Adding 0.003 to 0.5% by weight of a polymeric flocculant to the paper stock based on the total solid weight of the paper stock slurry, thereby increasing the retention and dehydration levels of the filler component in the paper stock. Preferred enhancers are condensates of phenol and formaldehyde, and preferred agglomerates contain acrylamide, methacrylamide, and / or N-vinylformamide. The method provides a significant advantage in the papermaking process while retaining the desired filler component in the final sheet, while not retaining undesirable filler components such as inks and dye particles present in the recycled papermaking stock.

Paper Making, Hold, Filler, Paper Making Material, Waste Glow, Enhancer, Tangle

Description

{SELECTIVE RETENTION OF FILLING COMPONENTS AND IMPROVED CONTROL OF SHEET PROPERTIES BY ENHANCING ADDITIVE PRETREATMENT}

TECHNICAL FIELD The present invention relates to the art of papermaking, and more particularly to wet-end additives added to paper making furnish.

In the papermaking process, paper is formed from an aqueous cellulose suspension containing cellulose fibers and selected inorganic pigments. Generally these cellulose slurries are diluted to a consistency of up to 1% (dry weight percent of solids in the slurry), usually up to 0.5% of consistency, in front of the paper machine. The size and shape of the particles present in the papermaking slurry (called papermaking stock) vary widely. These particles range in size from one micrometer or less for most inorganic pigments and dyes to a few millimeters for fibers. Generally, initial dewatering of the paper stock is carried out by ejecting the cellulose paper stock on or between the filter fabric (s), referred to as wire. The opening of such a wire is generally about 200 meshes, which corresponds to a pore size through which particles with a diameter of 76 micrometers can pass. If no attractive force acts between the particles, the inorganic pigment passes very easily through the wire and is not held in a sheet, thereby reducing the advantage of adding the inorganic pigment. Thus, under normal papermaking environments, many papermaking stock components that are so small in size to pass through the openings of the wire need to be deformed if they are to be retained on paper.

As the fibers form a mat on a wire, their own filtration medium is formed, and most of the small particles in the paper stock are trapped in the fiber mat by simple filtration, which causes the paper to This is especially true when it is thick, ie when the basis weight is heavy. However, despite the heavy basis weight, a significant portion of the small particulate matter may not be sufficiently retained in the sheet. If the basis weight is light or the formation of the mat is hampered by turbulence of the paper machine, the filtration mechanism for retaining the small particles is seriously insufficient. Under papermaking environments where this filtration mechanism is insufficient, the coagulation and / or flocculation of the particles may occur by altering the interparticle interactions using chemical treatment agents commonly referred to as retention aids. Needs to be.

Withholding small particle constituents provides many advantages for the papermaker. Since inorganic fillers, such as clay and calcium carbonate, are less expensive than fibers, the use of such fillers in place of fibers reduces raw material costs. It is also essential to withhold fillers and fiber fines in order to obtain the paper properties required for the desired end use. Examples of such paper properties include opacity, brightness and proper ink interaction. The small particles have a large surface area when aggregated into a predetermined mass, so that a large amount of additives such as dyes and sizing agents can be attached to these small particles, so that the fine particles necessary for effective use of such additives are fine. The retention force of the material can be obtained.

Filler particles or fibrous microparticles (so-called first passthrough) that are not initially held are mostly present in the paper stock over time, as most of them are recycled back to the paper stock through a white water system. The fraction of small particles is increased. However, these results are sometimes unsatisfactory for several reasons as follows. Because some of the important and expensive materials lose their effectiveness during recycling in white water systems, these materials need to be retained in the primary pass for performance and paper properties. Examples of such materials are titanium dioxide and alkaline sizing agents. In this way, the total amount of fines present in the sheet can be increased, but the distribution of the fines in the sheet is often very uneven, which can result in a two-sided phenomenon of the paper. In addition, the concentration of non-pending material in the paper machine's white water system is a cause of deposition problems and associated runnability problems that delay manufacturing and impair product quality. This problem is alleviated by the use of effective preservatives. Thus, the progress of the cleaner machine is improved, the fibers and fillers are used more efficiently, and the waste destined for the waste disposal facility of the paper machine is reduced.

Representative retention agents include polymeric coagulants, which are cationic solution polymers having low to medium molecular weights (10 ³ -10 ⁶ g / mole). Since these flocculants are polymers with high cationic charge density, it is believed that the retention activity of the flocculants is induced in the interaction with the negatively charged papermaking component. Because of the shear sensitivity and relatively small agglomeration size formed by the polymeric flocculant, these polymeric flocculants are rarely used alone as retention agents, but are used with the flocculant as a dual polymer program. In this way, it is believed that the flocculant can agglomerate the particles initially to more effectively entangle the particles.

Similarly, hydrolyzable aluminum salts are widely used as coagulants for papermaking. Because of the acid generated by the hydrolysis of aluminum, the pH of machines using alum decreases. Thus, this process is called "acidic papermaking process". Aluminum species with maximum cohesive capacity are formed in the pH range of 4-6. Polyaluminum chloride is also an effective flocculant. Such polyaluminum chloride flocculants can be used over a wide pH range, as they are partially neutralized and do not lower the pH to the extent that the alum is lowered.

Entangling describes a number of possible ways of providing aggregation of small particles. Different stages of flocculation are required at each step in the pulp and paper manufacturing plant. When forming a wire in a paper machine, paper is formed by rapidly dehydrating the paper stock. The retention agent acts as the components of the slurry clump before the slurry hardens in a successive dehydration step to form a sheet. Moderate levels of entanglement are required to provide the necessary retention and dehydration rates.

In a single polymer program, flocculants (typically cationic polymers) are the only substances added. This flocculating agent is added to the thin papermaking stock obtained after mixing the cellulose stream and the filler stream. Another method to improve the entanglement on the fiber mat of cellulose micromaterials, inorganic fillers and other paper stock components is a dual polymer program, also referred to as a flocculant / entanglement system, which is added in front of the paper machine. In such a system, a coagulant, such as a low molecular weight synthetic cationic polymer or cationic starch, is first added to a typical paper stock after mixing the cellulose stream and the filler stream to initially agglomerate the particles of the paper stock, followed by the addition of a tangle. do. Generally the tangle agent is a high molecular weight synthetic polymer. As the fiber mat of paper is formed, the presence of such large aggregates in the paper stock increases the retention. The aggregates are filtered on the fiber mat, while most of the non-aggregated particles pass through the fiber mat.

In systems containing high concentrations of anionic polymer / oligomeric materials, the performance of cationic polymers is often adversely affected. The anionic material may be an inorganic or organic material. The most representative examples of anionic harmful substances, also called "anionic trash", include silicates used as hydrogen peroxide stabilizers in pulping, bleaching and ink removal processes, and wood such as polygalacturonic acid and lignin derivatives. There is an extracted substance species. Nonionic polymers are affected by the anionic materials to a much lower extent than cationic polymers.

One example of a nonionic polymer system is a polyethylene oxide (PEO) and cofactor program. Such a system is an effective retention agent for newspaper paper and other mechanical pulp stocks. Known cofactors are kraft lignin, sulfonated kraft lignin, naphthalene sulfonate, tannin extract, and phenol-formaldehyde resins. A recent European patent application (Echt, EPO application 621 369 A1, 1995) discloses the use of poly (p-vinyl phenol) as cofactor. WO 95/21295 also describes that phenol sulfoneformaldehyde resins improve retention. However, these resins are added to those after the incorporation of the cationic polymer into the cellulose suspension.

Another way to use nonionic polymers with cofactors is by Huinig Xiao and R. Pelton. Xiao reported the synthesis of copolymers of acrylamide and poly (ethylene-glycol) methacrylate. Such copolymers contain pendant PEG chains. This chain interacts with the resol-type phenolic resin, as claimed by Xiao and Pelton, above, to form a three-dimensional structure that causes excellent performance as a retention polymer. Xiao and Pelton, however, do not report any beneficial effects of phenolic resins on the entanglement performance of polyacrylamide homopolymers. This information is summarized in WO 94/17243. Unexpectedly, a synergy between polyacrylamide homopolymers and certain cofactors such as phenolformaldehyde resins has been identified under appropriate conditions. This method is described in European Patent Application No. 0 773 319 A1.

Since filled paper requires less purification and is easier to dehydrate compared to unfilled paper, there is increasing interest in increasing the filler content of paper in terms of raw material costs and energy savings. The term filler as used herein includes calcium carbonate, various forms of clay, talc, titanium dioxide, gypsum, hydrated aluminum oxide, silica, plastic pigments, and the like. In addition, final paper properties such as opacity, brightness and printability can be improved by increasing the filler loading.

Attempts to improve the level of retention of fillers have focused on modifying the filler surface by chemical pretreatment. Commercial filler suppliers have chemically modified the filler particles by attaching / bonding a cationic polymer to the surface of the filler particles to be marketed as precision grade fillers. In a similar manner, chemical distributors pre-aggregate the filler by adding a cationic polymer to the filler slurry in situ at the paper mill before mixing the filler slurry with the fiber slurry. Pre-aggregation of such fillers is disclosed in PCT applications WO 86/04370, US Pat. Nos. 4,295,933 and 4,272,297, and British Patent 2,001,088.

Treatment of the filler with an aqueous colloidal dispersion of cationic melamine-formaldehyde resin followed by aqueous vinyl alcohol polymer solution to form a modified filler is described in US Pat. No. 4,495,245. Surface treatment of cationic fillers using dispersants, which are cationic polymer electrolytes, to make the filler particles into cations is disclosed in US Pat. No. 5,244,542. It is disclosed in US Pat. No. 4,943,349 to improve retention levels by tangling inorganic fillers and binders (eg, starches or synthetic polymers) before adding them to the fiber suspension. In these methods, it was found that the retention level of the filler in the final product was increased.

U.S. Patent 4,913,775 outlines the manner of addition of treatment agents for the production of paper and cardboard. FI 67735 discloses a method for improving retention levels by adding pre-mixable cationic polymers and anionic components, but this addition process does not provide optimal results. US Pat. No. 4,388,150 describes starch and colloidal silicic acid that can be premixed and added to the paper stock. The patent also states that this process does not provide the best results.

 US Pat. No. 5,670,021 discloses a papermaking process in which a mixture of alkali silicate and phenolformaldehyde resin is added to a filler prior to addition to the cellulose slurry. The resulting mixture is then treated with PEO agglomerate to improve filler retention levels, dehydration and paper formation in the papermaking process.

The use of nonionic programs containing PEO involves some very important conditions. High molecular weight PEOs used at the wet end are dry polymers that require very expensive and tedious makedown systems. If such PEOs are not prepared properly, such polymers can have a detrimental effect on progression due to the particulate residues contained therein, as well as dramatically degrade their performance. PEO is known to be chemically sensitive to some metal ions and residual oxidants present in the wet part of the paper machine. This lowering of the molecular weight results in unstable performance. The performance of these EPO-containing programs is known to be very sensitive to shear stress. This sensitivity hinders the performance of modern large paper machines that are shear stress intensive. Finally, due to the raw materials and processing involved, PEO is very expensive compared to many other water soluble polymers.

The present invention dramatically deviates from the prior art of improving filler retention levels based on chemical pretreatment of filler particles. The term filler component, as defined herein, is used in the sense to include small solids used for filling and changing properties, including, but not limited to, conventional fillers as described above. The present invention discloses the use of a new double polymer program in the papermaking process, in which the flocculant consists of a selected group of monomers. This new use also allows the papermaker to selectively withhold the filler relative to other ingredients present in the papermaking slurry. This new method of use does not necessarily improve the level of overall hold in order to provide the benefit of improved progression and paper properties. This use is for preferentially withholding portions of the paper stock with certain properties (eg fillers). Such fillers may be preferentially retained over cellulosic materials or in some cases may be preferentially retained over ink particles that degrade brightness.

The present invention dramatically deviates from conventional methods of improving filler retention levels based on chemical pretreatment of filler particles. The present invention teaches that the papermaking process can be improved by pretreatment of the filler as opposed to conventional methods of pre-tangling the filler. Specifically, the present invention teaches pretreatment of fillers with phenolic additives (enhancers) to improve retention of filler components and to improve runnability before introducing the filler stream into the cellulose paper slurry. . The addition of such additives can be carried out with or without adjusting the pH using common hydrogen atom donors such as dilute inorganic acids, but the final step of the tangle disclosed herein is when the pH of the filler is adjusted to about 5. The performance is significantly increased. The present invention also teaches that the above advantages can be maintained even when high levels of anionic harmful substances are present.

In the first step of the present invention, a phenolic enhancer is added to the desired filler component prior to mixing the filler slurry with the fiber slurry. Wherein the phenolic enhancer is mixed with the filler slurry and stored for a predetermined time and supplied separately as a product, or else the phenolic enhancer is added to the fiber slurry just before adding the filler slurry to the fiber slurry. mill and mix with the filler slurry in situ. The addition of such phenolic enhancers can be carried out with or without controlling the pH using common hydrogen atom donors such as dilute inorganic acids. In the next step of the present invention, the addition of an agglomerate to the paper stock containing the pretreated filler stream results in a significantly selective increase in the level of retention of fillers for other low brightness particles in the final paper produced. This interaction also improves the overall progress of the filler retention, dehydration, paper formation, and papermaking processes. Accordingly, the present invention discloses new applications for improving retention, paper formation, porosity uniformity, and overall dehydration levels, as well as selective retention of filler material to other particulate matter in the system.

The present invention provides a method for increasing the retention and dehydration levels of filler components in the paper stock used in the papermaking process. The method of the present invention comprises the steps of preparing a slurry of filler component; Treating the slurry with from about 0.003% to about 2.0% by weight phenolic enhancer based on the solid weight of the paper stock to form a pretreated filler component slurry; Adding about 0.003% to about 0.5% by weight of a polymeric flocculant to the paper stock, based on the total weight of solids in the paper stock slurry, before and after the filler is introduced into the paper stock. Increase the retention and dehydration levels of the filler components present in the paper stock. Preferred enhancers are condensates of phenol and formaldehyde, and preferred agglomerates are acrylamide homopolymers or copolymers.

The present invention provides an important advantage in many papermaking processes, while retaining the desired filler components in the final paper while not retaining undesirable components such as inks and dyes present in the paper stock.

One embodiment of the present invention is a method for increasing the retention and dehydration levels of a filler component in a paper stock used in a papermaking process, the method comprising

a) preparing a slurry of filler component;

b) treating the slurry with from about 0.003 to about 2.0 weight percent phenolic enhancer based on the weight of the total solids of the paper stock to form a pretreated filler component slurry;

c) adding the pretreated slurry of step b) to the paper stock;

d) adding from about 0.003 to about 0.5 weight percent of a polymeric tangle to the paper stock, based on the total solid weight of the papermaking material,

A method of increasing the retention and dehydration levels of the filler component in the papermaking stock.

Another embodiment of the present invention is a method for increasing the retention and dehydration level of a filler component in a paper stock used in a papermaking process, the method comprising

a) preparing a slurry of filler component;

b) treating the slurry with from about 0.003 to about 2.0 weight percent phenolic enhancer based on the total solid weight of the paper stock to form a pretreated filler component slurry;

c) adding from about 0.003 to about 0.5 weight percent of a polymeric tangle to the paper stock based on the total solid weight of the paper stock slurry;

d) adding the pretreated slurry of step b) to the paper stock,

A method of increasing the retention and dehydration levels of the filler component in the papermaking stock.

The following description applies to the embodiments of the present invention described above. The filler component can be selected from the group consisting of calcium carbonate, clay, silica, titanium dioxide, magnesium oxide, gypsum, talc, hydrated aluminum oxide, magnesium silicate and mixtures thereof. Such phenolic enhancers include, but are not limited to, phenol-formaldehyde resins, tannin extracts, naphthol-formaldehyde condensates, poly (para-vinyl phenols), as well as functional groups such as carboxylates, sulfonates, and phosphonates May be selected from the group consisting of said enhancer substituted with a functional group, and a mixture of said enhancers. Tannin extract as used herein refers to a naturally occurring polyphenolic substance present in organic extracts of some tree species bark.

The pH conditions of step a) are about 4 to 8, preferably about 4.5 to about 6.5. From about 0.007 to about 1.0 weight percent phenolic enhancer may be added in step b) based on the total solid weight of the papermaking stock. Preferably, from about 0.02 to about 0.5 weight percent phenolic enhancer may be added in step b) based on the total solid weight of the paper stock.

The paper stock may be selected from the group consisting of paper stock for manufacturing high-quality paper, cardboard, and newspaper paper, but is not limited thereto.

The tangle agent may be a nonionic, anionic, or cationic polymer. In addition, the coagulant may have a molecular weight of about 500,000 or more. The flocculant preferably has a molecular weight of about 1,000,000 or more, most preferably about 5,000,000 or more.

The method of the present invention preferably comprises adding from about 0.001 to about 1 weight percent cationic flocculant to the paper stock based on the total solid weight of the slurry; Or adding a processing aid selected from the group consisting of bentonite, talc, silica, cationic starch, mixtures thereof and the like to the paper stock.

The present invention relates to clays, silica, titanium dioxide, magnesium oxide, pulverized calcium carbonate pretreated with synthetic or natural polymers known as enhancers, containing groups such as phenol groups, naphthol groups, sulfonated phenol groups or sulfonated naphthol groups. Demonstrate improved retention levels of filler components, such as pulverized calcium carbonate, inorganic pigments, organic pigments, or any other small filler or alteration of solids, and that the phenolic material has a filler retention level with a certain tangle. Proves to improve significantly. As used herein, the term agglomerate includes acrylamide homopolymers, copolymers and terpolymers, methacrylamide homopolymers, copolymers and terpolymers, and N-vinylamide homopolymers, copolymers and terpolymers It is used in a sense not limited to this.

The present invention relates to a method for increasing the retention and dehydration levels of a filler component in a paper stock used in the papermaking process, wherein the method comprises from about 0.003 to about 2.0% by weight of phenolic based on the total weight of solids in the paper stock. Adding the enhancer to the filler component slurry. At this time, the addition of the phenolic enhancer to the filler component slurry is carried out on-site at the paper mill or at a previous place to make the filler component into a product. To the papermaking stock containing the pretreated filler component, from about 0.001 to about 0.5% by weight (entangled active ingredient) of agglomeration agent, based on the total solid weight of the papermaking stock, is added.

It is not necessary to pretreat all of the fillers introduced into the papermaking slurry. Some of the fillers may be pretreated with the enhancer and then mixed with the untreated filler prior to introduction into the cellulose containing slurry. In addition, the pretreated filler stream may be separated and added in part at different locations during the papermaking process. Specifically, some of the pretreated fillers may be added before or after introducing the flocculant. Some of the pretreated fillers may be added before and after high shear regions such as fan pumps and pressure screens.

The amount of the phenolic enhancer is preferably about 0.003 to 2.0 wt%, more preferably about 0.007 to about 1.0 wt%, and most preferably about 0.02 to about 0.5 wt%, based on the total solid weight of the paper stock. to be.

Typically, pretreatment of the filler with the enhancer may require several seconds of retention time and appropriate mixing such as those associated with line dilution or static mixers. Of course, the contact time and mixing strength between the enhancer and the filler may vary. In general, performing the pH adjustment step during pretreatment improves performance. The need for such adjustment is confirmed by the observed performance. If adjustment to the most beneficial pH of about 5 is required, this is achieved by using dilute solutions of proton donors such as inorganic acids.

The flocculating agent used in the present invention is generally selected from nonionic, cationic, anionic flocculating agents and the like. Examples of such nonionic flocculating agents include homopolymers, copolymers and terpolymers of nonionic monomers. Preferred nonionic monomers are acrylamide or methacrylamide or N-vinylformamide, and thus preferred nonionic flocculating agents are poly (acrylamide), poly (methacrylamide) or poly (N-vinylformamide), respectively.

 The amount of the nonionic flocculating agent consisting of acrylamide, methacrylamide and / or N-vinylformamide polymer is preferably from about 0.001 to about 0.5% by weight, more preferably from about 0.001% by weight, based on the total solid weight of the paper stock slurry. 0.003 to about 0.2 weight percent, most preferably about 0.007 to about 0.1 weight percent.

Nonionic flocculating agents usefully used in the practice of the present invention are acrylamide, methacrylamide, N-tert butyl acrylamide, N-vinylformamide, N-vinylpyrrolidone, N-vinylpiperidone, N- Vinyl caprolactam, N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-5-phenylpyrrolidone, N-vinyl-2-oxazolidone, N-vinyl It is formed from at least one monomer selected from the group consisting of imidazole, vinyl acetate, maleimide and N-vinylmorpholinone and the like. Such monomers may be polymerized to form homopolymers. When mixed and polymerized, a copolymer or terpolymer may be obtained.

Cationic or anionic acrylamide or N-vinylamide copolymers or terpolymers may be used in place of the nonionic acrylamide or N-vinylamide polymer agglomerates. In some cases, such as when using anionic acrylamide or N-vinylamide copolymers or terpolymer coagulants, a cationic flocculant must be added to the slurry prior to adding the agglomerate. The amount of such flocculant is preferably about 0.001 to about 1% by weight, more preferably about 0.01 to about 0.5% by weight, most preferably about 0.02 to about 0.25% by weight based on the total solid weight of the paper stock slurry. .

As used herein, the term cationic flocculant is intended to include all water-soluble copolymers of meta (acrylamide) capable of carrying positive charges when dissolved in water, regardless of whether the positive charge carrying capacity depends on pH. I understand. Examples of cationic copolymers of meta (acrylamide) include copolymers of meta (acrylamide) and dimethylaminoethyl methacrylate (DMAEM), copolymers of meta (acrylamide) and dimethylaminoethyl acrylate (DMAEA), Copolymers of meta (acrylamide) and diethylaminoethyl acrylate (DEAEA), copolymers of meta (acrylamide) and diethylaminoethyl methacrylate (DEAEM), meta (acrylamide), and Copolymers of quaternary ammonium form with dimethyl sulfate or methyl chloride, copolymers of meta (acrylamide) and Mannich reaction modified polyacrylamides, of meta (acrylamide) and diallylcyclohexylamine hydrochloride (DACHA HCl) Copolymer, copolymer of meta (acrylamide) and diallyldimethylammonium chloride (DADMAC), meta (acrylamide) and methacrylamidopropyl Copolymers of dimethylammonium chloride (MAPTAC) and copolymers of meta (acrylamide) and allyl amine (ALA).

In addition, as used herein, the term cationic flocculant includes any water-soluble form of N-vinylformamide or a monomer associated therewith that is capable of carrying a positive charge when dissolved in water, regardless of whether the charge carrying capacity depends on pH. It is understood that copolymers may be included. Examples of such cationic copolymers of N-vinylformamide include copolymers of N-vinylformamide and dimethylaminoethyl methacrylate (DMAEM), copolymers of N-vinylformamide and dimethylaminoethyl acrylate (DMAEA). , Copolymer of N-vinylformamide with diethylaminoethyl acrylate (DEAEA), copolymer of N-vinylformamide with diethylaminoethyl methacrylate (DEAEM), N-vinylformamide, and the acrylate Copolymer of quaternary ammonium form with dimethyl sulfate or methyl chloride, copolymer of N-vinylformamide with Mannich modified polyacrylamide, N-vinylformamide and diallylcyclohexylamine hydrochloride (DACHA HCl) Copolymer of N-vinylformamide and diallyldimethylammonium chloride (DADMAC), copolymer of N-vinylformamide and methacrylamidopropyltrimethylammonium There is a copolymer of a low-grade copolymer, and N- vinyl formamide and allyl amine (ALA) of (MAPTAC).

The high molecular weight anionic polymer is preferably a water soluble vinyl copolymer of (meth) acrylamide and the following monomers: acrylic acid, 2-acrylamido-2-methylpropane sulfonate (AMPS) and mixtures thereof. Further, the anionic high molecular weight flocculant is a hydrolyzed acrylamide polymer, or acrylamide or its homologue (e.g. methacrylamide) and acrylic acid or its homologue (e.g. methacrylic acid), or a monomer (e.g. male) Acid, itaconic acid, vinylsulfonic acid, AMPS, or other sulfonate-containing monomers). The anionic polymer may be a sulfonate or phosphonate containing polymer synthesized by modifying the acrylamide polymer in a manner such that sulfonate or phosphonate substituents, or mixtures of these substituents, are obtained. Most preferred high molecular weight anionic tangles are acrylic acid / acrylamide copolymers, and 2-acrylamide-2-methylpropane sulfonate / acrylamide copolymers (AMPS), acrylamidomethane sulfonate / acrylamide (AMS), Sulfonate-containing polymers such as acrylamido ethane sulfonate / acrylamide (AES) and 2-hydroxy-3-acrylamide propane sulfonate / acrylamide (HAPS).

The high molecular weight anionic polymer is preferably a water-soluble vinyl copolymer of N-vinylformamide or a monomer associated therewith with the following monomers: acrylic acid, 2-acrylamido-2-methylpropane sulfonate (AMPS) and mixtures thereof . Further, the anionic high molecular weight flocculant is a hydrolyzed acrylamide polymer, or acrylamide or its homologue (e.g. methacrylamide) and acrylic acid or its homologue (e.g. methacrylic acid), or a monomer (e.g., Copolymers of maleic acid, itaconic acid, vinylsulfonic acid, AMPS, or other sulfonate-containing monomers). The anionic polymer may be a sulfonate or phosphonate containing polymer synthesized by modifying the acrylamide polymer in such a way that a sulfonate or phosphonate substituent or a mixture of these substituents is obtained. The preferred high molecular weight anionic tangles are acrylic acid / acrylamide copolymers, and 2-acrylamide-2-methylpropane sulfonate / acrylamide copolymers (AMPS), acrylamidomethane sulfonate / acrylamides (AMS), Sulfonate-containing polymers such as acrylamido ethane sulfonate / acrylamide (AES) and 2-hydroxy-3-acrylamide propane sulfonate / acrylamide (HAPS).

 Nonionic, cationic and anionic flocculating agents preferably have a molecular weight of at least 500,000. More preferred molecular weight is at least about 1,000,000, but best results were obtained when the molecular weight was at least about 5,000,000. The anionic or cationic monomer may constitute up to about 80 mole percent of the copolymer, but best results were obtained when the anionic or cationic charge varied within the range of about 0 to 30 mole percent.

The high molecular weight flocculants (anionic, nonionic, cationic) can be used in the form of a solid, an aqueous solution, a water-in-oil emulsion, or a dispersion in water.

Additives for inhibiting harmful substances such as bentonite, talc, cationic starch, cationic flocculants, or mixtures thereof may be added at any point in the system. A preferred addition point is the thick papermaking pulp before dilution with white water. The use of such additives increases the cleanliness of the papermaking operation, but if the additives are not used, hydrophobic precipitation may occur which adversely affects productivity and paper quality.

Typically the flocculant is a cationic polymer having a low molecular weight of about 1,000 to about 500,000. More preferably, the molecular weight is about 2,000 to about 200,000.

Examples of polymers used as flocculants include quaternized dimethylaminoethylacrylate, quaternized dimethylaminomethacrylate, vinyltrimethoxysilane, acrylamide, diallyldimethylaminoalkyl (meth) acrylate, diallyldimethylaminoalkyl ( And copolymers formed from diallyldimethylammonium chloride with monomers selected from the group consisting of meta) acrylamide and mixtures thereof. In addition, polymers that can be used include polyethylene imine, polyamine, polycyanodiamide formaldehyde, poly (diallyldimethylammonium chloride), poly (diallyldimethylaminoalkyl (meth) acrylate), poly (diallyldimethylaminoalkyl (Meth) acrylamide), copolymers formed from acrylamide and / or diallyldimethylaminoalkyl (meth) acrylate and diallyldimethylaminoalkyl (meth) acrylamide, as well as condensation polymers of dimethyl amine and epichlorohydrin , A condensation polymer of ammonia and ethylene dichloride, or a copolymer of acrylamido N, N-dimethyl piperazine quaternary salt with acrylamide.

In addition, polymeric flocculants that can be used in the present invention are those that can be polymerized with esters, amides, nitriles or salts of (meth) acrylic acid, such as amidine vinylformamide, vinyl alcohol, vinyl acetate, and vinyl pyrrolidone. Poly (vinylamine) such as those formed from one or more monomers selected from the group consisting of. In addition, the flocculant may be an inorganic material such as alum. In addition, the present invention can be applied to a papermaking slurry selected from the group consisting of fine paper, cardboard, and newspaper paper slurry. Such slurries include wood containing, wood free, first used, recycled and mixtures thereof. It is believed that the method of the present invention can be applied to all grades and types of paper products containing the filler components described herein.

The phenolic enhancer is a phenol-formaldehyde resin, tannin extract, naphthol-formaldehyde condensate, poly (para-vinyl phenol), as well as said enhancer substituted by functional groups such as carboxylate, sulfonate, phosphonate and the like , And mixtures thereof.

Other additives may be added to the cellulose slurry that do not substantially interfere with the activity of the tangle / phenolic enhancer combination of the present invention. Examples of such other additives include size agents such as alum and rosin, particulates, pitch control agents, and biocides.

The amount of filler component generally used in papermaking stock is about 5 to about 30 parts by weight per 100 parts by weight of dry pulp of the slurry, but the amount of such filler components may be as low as about 1 part by weight or as high as about 50 parts by weight.

In order to measure the efficiency of the method described herein, the following Britt Jar experimental method was used. The Brit rule test method is an industrial certification test evaluation method of FPR and FPAR. First Pass retention (FPR) refers to the degree of incorporation of the entire solid into the sheet formed. This is calculated from the consistency of the papermaking slurry, C _s, and the white water, C _ww , obtained during the formation of the sheet as represented by the following equation:

FPR = ((C _s -C _ww ) / C _s ) X 100%

Therefore, the higher the FPR value, the higher the efficiency of the treatment agent.

First Pass Ash retention (FPAR) is an indication of the degree of incorporation of filler into the sheet formed. This FPAR is calculated from the filler _viscosity C _fs of the initial papermaking slurry obtained during the formation of the sheet and the filler _viscosity C _fww of the white water, as shown by the equation:

FPAR = ((C _fs -C _fww ) / C _fs ) X 100%

Therefore, the higher the FPAR value, the higher the processing efficiency.

The briddle consists of a shielded container, an impeller, a screen for performing dehydration (typically 200-70 mesh) and a valve. These brits are used to replicate the shear conditions of the paper machine. The experiment was carried out by operating the impeller while adding a sample of paper stock having a known consistency to the paper mill (from a paper mill in the Midwest) to the breeze. The paper stock was then treated with a dilute treatment solution to be evaluated in order that best reflects the addition point to the paper machine. After the experiment was finished, 100 ml of white water sample (effluent passed through Brit's filter) was collected under dynamic conditions. Dynamic conditions were used to prevent the formation of mats during dehydration.

The consistency of the paper stock as used in the experiment was 0.2 to 0.7%. In these ranges, the retention level value was found not to depend on the consistency of the fee. The polymer used in all experiments was diluted to 1% for flocculants and phenolic enhancers and 0.1% for flocculation agents. The Britza's impeller was operated at 800 rpm.

The Britza test focuses on attraction or repulsion rather than hydrodynamic factors on retention of paper, focusing on the effect of colloidal factors on retention levels, i.e. physical trapping of micromaterials and mechanical entanglement of fibers. It is used to replicate the level of retention on paper machines.

Thus, the retention level value measured does not include a factor relating to filtration and thus represents a pure chemical retention component.

In each test, additives were added in the order in which they were added to the paper stock on the paper machine. All samples were stirred for the same time whether or not all additives were introduced into the given test. Each test was performed by placing the paper stock in an upper chamber located above the screen and processing in the following order:

0 seconds-application fee

5 seconds-clay (pretreated or not pretreated)

10 seconds-phenolic enhancer added for experiments without pretreatment

15 sec-Add Tangle

20 sec-sample collection

Next, the dried and after ashing (ashing) through filtration pad was measured in the consistency C _ww and filler consistency in the white water in the white water _fww C. Next, these values were used to calculate FPR and FPAR.

The following examples are presented to illustrate preferred embodiments and uses of the invention and are not intended to limit the scope of the invention as set forth in the claims. Unless stated otherwise, in the following examples% means% by weight

Example 1

Table I below shows the data obtained from the experiment using the papermaking fee for the production of newspaper paper. The paper stock is prepared by using a thick heat treatment pulp (TMP) sample obtained from a newspaper paper manufacturing plant. A 20% calcined earth filler, available from Engelhard Corporation, Iselin, New Jersey, USA, was introduced into the application fee. The consistency was adjusted to 0.5%.

Before incorporating the filler into the papermaking slurry, the effect obtained when introducing the phenolic enhancer into the filler as a pretreatment agent was evaluated in comparison with the case where the enhancer was not introduced, i.e., when the filler was used in a conventional manner. The phenolic enhancer was a commercially available phenol formaldehyde resin of the resol type. During the pretreatment of the filler all the enhancers were added to the filler and then the filler was introduced into the cellulose containing papermaking slurry. The pH of the filler prepared as a slurry using tap water was 7. For pretreatment experiments involving adjustment of pH, the pH was lowered to 6 using a dilute solution of inorganic acid.

The nonionic tangle was a latex inverse emulsified homopolymer acrylamide having a RSV of 20.0% total solids content of 30.0 dl / g and commercially available from Nalco Chemical Company, Naperville, Illinois, USA. The amount of the flocculant used was 2 kg of product per tonne of solid of the support material. The amount of the phenolic enhancer obtained in 41.5% solids from Borden Chemical Co., Shivoigan, WI, was 2 kg (active ingredient) per tonne of total solid of the refining agent.

Surprisingly, the pretreatment of the filler with the phenolic material followed by the use of acrylamide homopolymers as a tangle has been shown to improve retention levels as the FPR shows higher values. It is clear from this example that adjusting the pH of the filler prior to pretreatment with the phenolic enhancer improves the retention level. The retention level measurement was performed using the above described Britza process.

Table 1

Influence of Pretreatment on the Retention Level of Calcined Soils Using Nonionic Polyacrylamides as Entangling Agents

1st Pass Hold Level  First pass ash hold level No pretreatment 77.9 68.2 Pretreatment 83.1 75.5 Pretreatment with changing pH 87 81.8

Example 2

Table II below shows the data obtained from the experiment using the papermaking fee for the production of newspaper paper. The paper stock is prepared by using a thick TMP sample obtained from a newspaper paper manufacturing plant. A 20% water-washed kaolinto filler, available from Engelhard Corporation, Eiselin, NJ, was introduced into the application fee. The consistency was adjusted to 0.5%.

Before incorporating the filler into the papermaking slurry, the effect obtained when the phenolic enhancer was introduced into the filler as a pretreatment agent was evaluated in comparison with the case where the enhancer was not introduced, i.e., when the filler was used in a conventional manner. The phenolic enhancer was a commercially available phenol formaldehyde resin of the resol type. During the pretreatment of the filler all the enhancers were added to the filler and then the filler was introduced into the cellulose containing papermaking slurry. The pH of the filler prepared as a slurry using tap water was 7. For pretreatment experiments involving adjustment of pH, the pH was lowered to 6 using a dilute solution of inorganic acid.

The nonionic tangle was a latex inverse emulsified homopolymer acrylamide having a RSV of 20.0% total solids content of 30.0 dl / g and commercially available from Nalco Chemical Company, Naperville, Illinois, USA. The amount of the flocculant used was 2 kg of product per tonne of total solid of the support material. The amount of the phenolic enhancer obtained in 41.5% solids from Borden Chemical Co., Shivoigan, WI, was 2 kg (active ingredient) per tonne of total solid of the refining agent.

If the filler was pretreated with the phenolic material without pH adjustment and acrylamide homopolymer was used as the tangle, it was found that the retention level did not improve. Surprisingly, however, it is confirmed in this example that the retention level is increased by adjusting the pH of the filler prior to pretreatment with the phenolic enhancer. The retention level measurement was performed using the above described Britza process.

Table II

Effect of Pretreatment on Washing Clay with Nonionic Polyacrylamides as a Tangle

1st Pass Hold Level  First pass ash hold level No pretreatment 68.1 55 Pretreatment 67.6 54.6 Pretreatment with changing pH 73.1 65.1

Example 3

Table III below shows the data obtained from the experiment using the preparation fee for producing newspaper paper. The paper stock is prepared by using a thick TMP sample obtained from a newspaper paper manufacturing plant. J.M. in Habre de Grace, Maryland, United States. A 20% amorphous silica filler, available from Huber, was introduced into the support. The consistency was adjusted to 0.5%.

Before incorporating the filler into the papermaking slurry, the effect obtained when introducing the phenolic enhancer into the filler as a pretreatment agent was evaluated in comparison with the case where the enhancer was not introduced, i.e., when the filler was used in a conventional manner. The phenolic enhancer was a commercially available phenol formaldehyde resin of the resol type. During the pretreatment of the filler all fillers were added to the filler and then the filler was introduced into the cellulose containing papermaking slurry. The pH of the filler prepared as a slurry using tap water was 7. For pretreatment experiments involving adjustment of pH, the pH was lowered to 6 using a dilute solution of inorganic acid.

The nonionic tangle was a latex inverse emulsified homopolymer acrylamide having a RSV of 20.0% total solids content of 30.0 dl / g and commercially available from Nalco Chemical Company, Naperville, Illinois, USA. The amount of the phenolic enhancer is shown in the first column of Table III below, and all the amount is based on the total solid weight of the support material.

The use of acrylamide homopolymer as a tangle after pretreatment of the filler confirmed a significant improvement in retention levels. The retention level measurement was performed using the above described Britza process.

TABLE III

Improvement of retention level when pretreatment with enhancer using amorphous silica as filler and nonionic acrylamide as tangle

Enhancer Pretreatment (kg / t) First Pass Hold Level (%) First Pass Ash Hold Level (%) 0 64.5 38.7 0.6 65.0 44.4 1.2 67.7 55.6 1.8 72.5 61.4 3.5 76.4 75.9

As described above, according to the present invention, by pre-treating the filler with a phenolic enhancer before adding the filler to the paper stock, it is possible to improve the retention and dehydration level of the filler in the support material.

Modifications and configurations of the method according to the present invention described above can be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims (22)

A method for increasing the retention and dehydration levels of filler components in paper stock used in the papermaking process, the method comprising a) preparing a slurry of filler component at a pH of 4 to 8; b) treating said slurry with 0.003 to 2.0 weight percent phenolic enhancer based on the total solid weight of said paper stock to form a pretreated filler component slurry; c) adding the pretreated slurry of step b) to the paper stock; d) adding a polymeric tangle having a molecular weight of at least 500,000 to the paper stock in an amount of 0.003 to 0.5% by weight, based on the total solid weight of the paper stock slurry. To increase the retention and dehydration levels of the. The method of claim 1 wherein the filler component is selected from the group consisting of calcium carbonate, clay, silica, titanium dioxide, magnesium oxide, gypsum, talc, hydrated aluminum oxide, magnesium silicate and mixtures thereof. The method of claim 1 wherein the phenolic enhancer is selected from the group consisting of phenol-formaldehyde resins, tannin extracts, naphthol-formaldehyde condensates, poly (para-vinyl phenols), and mixtures thereof. The method of claim 1, wherein the phenolic enhancer in step b) is added in an amount of 0.007 to 1.0% by weight based on the total solid weight of the papermaking stock. The method of claim 1 wherein the phenolic enhancer in step b) is added in an amount of 0.02 to 0.5% by weight based on the total solid weight of the papermaking stock. The method of claim 1, wherein the paper stock is selected from the group consisting of paper, cardboard, and newspaper stock. The method of claim 1, wherein the flocculating agent is an anionic polymer. The method of claim 1, wherein the flocculating agent is acrylamide, methacrylamide, N-tert butyl acrylamide, N-vinylformamide, N-vinylpyrrolidone, N-vinylpiperidone, N-vinyl caprolactam, N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-5-phenylpyrrolidone, N-vinyl-2-oxazolidone, N-vinylimidazole, A nonionic polymer formed by polymerization of a monomer selected from the group consisting of vinyl acetate, maleimide, N-vinylmorpholinone and mixtures thereof. The method of claim 1 wherein the flocculating agent is a cationic polymer. The method of claim 1, further comprising adding a cationic flocculant to the paper stock in an amount of 0.001 to 1 weight percent based on the total solid weight of the paper stock slurry. The method of claim 1, further comprising adding a processing aid selected from the group consisting of bentonite, talc, silica, cationic starch, and mixtures thereof. A method for increasing the retention and dehydration levels of filler components in the paper stock of the paper making process, a) preparing a slurry of filler component at a pH of 4 to 8; b) treating said slurry with 0.003 to 2.0 weight percent phenolic enhancer based on the total solid weight of said paper stock to form a pretreated filler component slurry; c) adding a polymeric tangle agent having a molecular weight of at least 500,000 to the paper stock in an amount of 0.003 to 0.5% by weight based on the total solid weight of the paper stock; d) adding the pretreated slurry of step b) to the paper stock, thereby increasing the retention and dehydration levels of the filler component in the paper stock. 13. The method of claim 12, wherein said filler component is selected from the group consisting of calcium carbonate, clay, silica, titanium dioxide, magnesium oxide, gypsum, talc, hydrated aluminum oxide, magnesium silicate and mixtures thereof. 13. The method of claim 12, wherein the phenolic enhancer is selected from the group consisting of phenol-formaldehyde resins, tannin extracts, naphthol-formaldehyde condensates, poly (para-vinyl phenols), and mixtures thereof. The method of claim 12, wherein the phenolic enhancer in step b) is added in an amount of 0.007 to 1.0% by weight based on the total solid weight of the paper stock. The method of claim 12, wherein in step b) the phenolic enhancer is added in an amount of 0.02 to 0.5% by weight based on the total solid weight of the papermaking stock. 13. The method of claim 12, wherein the paper stock is selected from the group consisting of high quality paper, cardboard, and newspaper paper. 13. The method of claim 12, wherein the flocculating agent is an anionic polymer. The method of claim 12, wherein the flocculating agent is acrylamide, methacrylamide, N-tert butyl acrylamide, N-vinylformamide, N-vinylpyrrolidone, N-vinyl piperidone, N-vinyl caprolactam, N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-5-phenylpyrrolidone, N-vinyl-2-oxazolidone, N-vinylimidazole, A nonionic polymer formed by polymerization of a monomer selected from the group consisting of vinyl acetate, maleimide, N-vinylmorpholinone and mixtures thereof. 13. The method of claim 12, wherein the flocculating agent is a cationic polymer. 13. The method of claim 12, further comprising adding a cationic flocculant to the paper stock in an amount of 0.001 to 1 weight percent based on the total solid weight of the paper stock slurry. 13. The method of claim 12, further comprising adding a processing aid selected from the group consisting of bentonite, talc, silica, cationic starch and mixtures thereof.