JP2017500454A - Method for improving size efficiency of ASA emulsion emulsified with polymeric emulsifier - Google Patents

Abstract

The present invention relates to a method for improving the size efficiency of ASA sizing agents in a papermaking process. Specifically, the present invention is modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound as a pulp slurry by sizing a pulp slurry by using an ASA emulsion emulsified with a polymer emulsifier as a sizing agent. Adding the papermaking filler particles to the pulp slurry.

Description

  The present disclosure relates to a method for improving the size efficiency of ASA sizing agents in a papermaking process. Specifically, the present invention relates to a method for improving the size efficiency of an ASA emulsion emulsified with a polymer emulsifier by treating papermaking filler particles with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound in a papermaking size process. About.

  Paper is typically a cellulose-containing fiber composite that has polar and strong hydrophilic properties, i.e. it is easily wetted and swollen by aqueous systems. This property results in excessive and uncontrollable penetration of water and other liquids (eg, inks, printing inks) into the fibrous web when writing and stamping on paper and when processing paper. The resulting problems include a decrease in internal fiber bonding strength, a deterioration in mechanical properties, a decrease in dimensional stability, and a very poor writing and stamping ability.

  In order to control the wetting and osmotic behavior, so-called sizing agents are used which act opposite to the behavior described above through partial hydrophobization. These adjuvants can be added to aqueous cellulose pulp (internal addition size) and applied by means of surface treatment of a pre-formed paper web using a suitable application system such as size press, film press, coater, etc. Both doing (surface size) is possible. For some types of paper, both methods are used together.

  In neutral or weakly alkaline papermaking processes, neutral sizing agents are used, such as typical neutral sizing agents including, for example, alkyl ketene dimers (AKD) and alkenyl succinic anhydrides (ASA). In recent years, the use of neutral sizing agents for paper and cardboard sizes has become common throughout the world. In general, the neutral sizing agent itself is a water-insoluble oil. Therefore, it must be in an emulsion state before being added to the furnish due to the size added internally. In order to obtain a stable emulsion of a neutral sizing agent, a suitable emulsifier is most important. Cationic starch and synthetic acrylamide polymers are usually used as emulsifiers. A large amount of cationic starch must be used to achieve the target size efficiency, but due to the fact that the use of a relatively much smaller amount of synthetic polymer provides a similar effect compared to cationic starch. Polymer emulsifiers are attracting attention. Further, the use of large amounts of cationic starch can greatly increase the level of chemical oxygen demand (COD) in the water released from the paper mill and cause severe environmental pollution. From the viewpoint of environmental conservation, it is desirable to replace the cationic starch with a cationic polymer.

In another aspect, more and more fillers, such as CaCO ₃ , TiO _2, are added to the paper to reduce fiber consumption due to cost reduction requirements. However, such fillers typically used adversely affect the size of the alkaline paper. Increasing the ash content, ie adding more filler, negatively affects the neutral size. More specifically, the neutral size effect when using polymeric emulsifiers is not ideal compared to cationic starch emulsifiers.

  Several publications report that size efficiency can be improved by surface treating the filler, with a focus mainly on modification of the hydrophobicity of the filler and processing techniques. US Pat. No. 5,411,639 discloses that a starch / fatty acid soap complex digests starch and then an aqueous solution of the starch and a fatty acid soap (a sodium or potassium salt of a fatty acid) under certain conditions. It discloses that it can be obtained by mixing. When such a composite is used to modify the filler, the AKD size efficiency can be effectively improved. US Pat. No. 5,527,430 also discloses a method to improve the size efficiency of ASA, where the polymer is used to surface-modify the filler so that the surface of the filler is hydrophobic. Is done. In both methods, fatty acids, or salts of fatty acids, are used, and starch / fatty acid complexes are used in large quantities resulting in complex processes. The use of large amounts of chemicals for surface modification of calcium carbonate is not economically suitable for practical use.

US Pat. No. 5,411,639 US Pat. No. 5,527,430 U.S. Pat. No. 3,102,064 U.S. Pat. No. 4,657,946 US Pat. No. 6,491,790

  In view of the above disadvantages in the prior art, the present invention provides a method for improving the size efficiency of an ASA emulsion emulsified with a polymer emulsifier, which can significantly improve the efficiency of a neutral size. To solve the problem.

  It has been found that the size efficiency of ASA emulsions emulsified with polymeric emulsifiers can be significantly improved by using paper filler particles modified with hydroxyl-containing hydrocarbon natural polymeric polysaccharide compounds as paper fillers. It was. Moreover, it has been surprisingly found that the above effects can be achieved by modifying paper filler particles with only very small amounts of hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds.

  That is, the present invention is a method for improving the size efficiency of an ASA emulsion emulsified with a polymer emulsifier in a papermaking process, wherein the pulp slurry is sized by using the ASA emulsion emulsified with a polymer emulsifier as a sizing agent. And a step of adding, as a papermaking filler, papermaking filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound into a pulp slurry.

  Furthermore, the present invention provides a papermaking filler particle modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide simultaneously with or before or after the addition of an ASA emulsion emulsified with a polymer emulsifier into the pulp slurry. A method for papermaking is provided, comprising the step of adding to the paper.

  According to the present invention, when a polymer emulsifier is used as an emulsifier, the size efficiency of ASA size can be significantly improved. According to the present invention, the size efficiency of an ASA emulsion emulsified with a synthetic polymer does not fall below the size efficiency of an ASA emulsion emulsified with a cooking cationic starch emulsifier.

  Unless defined otherwise, scientific and technical terms herein have the same meaning as understood by one of ordinary skill in the art. In the event of a conflict, the meaning used in this specification should prevail.

The present invention is a method for improving the size efficiency of an ASA emulsion emulsified with a polymer emulsifier in a papermaking process, comprising:
Sizing the pulp slurry by using an ASA emulsion emulsified with a polymer emulsifier as a sizing agent;
Adding a papermaking filler particle modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound into a pulp slurry as a papermaking filler;
Providing a method.

ASA
In this context, ASA refers to alkenyl succinic anhydride and is known as a neutral sizing agent (see US Pat. No. 3,102,064). ASA sizing agents are available, for example, from Nalco Co. N7540, N7542 and N7543 manufactured by Kemi Co. It is commercially available as AS2300, etc. ASA is a water-soluble oil, and the mixture with water exists as an emulsion. In order to obtain a stable ASA emulsion, an emulsifier must be used.

Polymer emulsifiers Examples of emulsifiers for emulsifying ASA emulsions include cationic starch and acrylamide synthetic polymers. In this context, the polymer emulsifier can be a water-soluble acrylamide compound, which consists of a copolymer of acrylamide and a cationic monomer and a copolymer of acrylamide and a cationic monomer cross-linked with glyoxal. It can be selected from a group.

  In the present specification, the cationic monomer is dimethyldiallylammonium chloride, methylacrylyloxyethyltrimethylammonium chloride, N, N, N-trimethyl-3- (2-methylallylamido) -1-propylammonium chloride, N, N'-dimethylaminoethyl methacrylate, quaternary ammonium salt cation of N, N'-dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, quaternary ammonium salt of dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and diethylaminoethyl acrylate It can be selected from the group consisting of quaternary ammonium salts.

  For example, the polymer emulsifier is a copolymer of acrylamide and a cationic monomer having a weight average molecular weight of 10,000 to 1,000,000 daltons, wherein the ratio of cationic monomer units to acrylamide units is 1/99. It may be a copolymer that is between 20/80, for example between 2/98 and 18/82, or for example between 5/95 and 15/85.

  In this context, “cationic monomer unit” refers to a moiety derived from a cationic monomer of a polymer and “acrylamide unit” refers to a moiety derived from acrylamide of a polymer. “Glyoxal unit” refers to a moiety derived from glyoxal of a polymer.

  For example, a polymer emulsifier is a copolymer of glyoxal cross-linked acrylamide and a cationic monomer having a weight average molecular weight of 100,000 to 3,000,000 daltons, wherein the ratio of acrylamide units to cationic monomer units is Between 5/95 and 95/5, and the ratio of glyoxal units to acrylamide units is between 60/40 and 5/95, or such as between 50/50 and 10/90, or such as 45/55. It may be a copolymer that is between 10/90.

  More specifically, the polymer emulsifier may be selected from the group consisting of a copolymer of methyl acrylyloxyethyl trimethyl ammonium chloride and acrylamide, and dimethyl diallyl ammonium chloride acrylamide crosslinked with glyoxal.

  Nalco Co. Manufactured by N7541 and N63007, and Buckman Co. Bubond 650 made by the company is an example of a commercially available polymer emulsifier that can be used.

ASA emulsions emulsified with polymeric emulsifiers ASA emulsions emulsified with polymeric emulsifiers are known in the art, for example by reference to US Pat. Nos. 4,657,946 and 6,491,790. The preparation of an ASA emulsion emulsified with a polymer emulsifier is, for example, a step of mixing 0.01 to 10 parts by weight of a polymer emulsifier with 50 to 99.9 parts by weight of water, and then 0.01 to 40 parts by weight. Of ASA and stirring for 1-2 minutes under high shear conditions. As used herein, “high shear conditions” means that ASA is dispersed into water by mechanical force to form an emulsion. High shear conditions can be achieved by methods known in the art. For example, it can be achieved by a homogenizer or a turbo pump. The ASA content in the ASA emulsion emulsified with the polymer emulsifier may be 0.01 to 10% by weight. The particle size of the emulsified ASA particles may be, for example, 0.1-5 μm, or such as 0.2-2 μm, or such as 0.5-1.5 μm.

Paper-made filler particles modified with hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds Paper-made filler particles modified with hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds are used for individual paper-made filler particles or for papermaking. A core formed by an aggregate of filler particles; and a coating layer formed by a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound and covering the surface of the core. Paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide can be composed of only the core and the coating layer. The “coating layer formed of the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound” contains only the hydroxyl-containing hydrocarbon natural polymer polysaccharide as a modifier for the filler particles for papermaking. Is meant to mean.

Hydroxyl-containing hydrocarbon natural macromolecular polysaccharide compounds refer to macromolecular polysaccharide carbohydrates formed by monosaccharide monomers (C ₆ H ₁₀ O ₆ ) via glucoside bonds. Specific examples may be selected from the group consisting of cellulose, cationic cellulose, chitosan, cationic chitosan, guar gum, cationic guar gum, cooked natural starch and cooked cationic starch, or any combination thereof. Specifically, the hydroxyl-containing hydrocarbon natural polymeric polysaccharide compound can also be any, eg, two or more combinations selected from a given example. For example, it may be a combination of cooked starch and one or more selected from cellulose, chitosan, guar gum or their cationic compounds. For example, it may be a cooked starch (a cooked natural starch and / or a cooked cationic starch herein). For example, it may be a cooked natural starch.

  “Paper for papermaking” or “filler for papermaking” is one grade of important raw material for papermaking and can replace a large amount of pulp fiber in the papermaking process. The use of fillers can substantially reduce papermaking costs and improve whiteness, opacity, smoothness, final paper gloss, printability and writing ability, and / or dimensional stability. Under some conditions, it can also improve stock drainage at the wet end and reduce papermaking costs. The papermaking filler may be an inorganic filler or an organic filler. The inorganic filler can be selected from, for example, kaolin, calcium carbonate, talc, titanium dioxide, aluminum hydroxide, calcium sulfate and amorphous silicate, or any combination thereof. For example, the inorganic filler may be a combination of calcium carbonate and one or more selected from kaolin, talc, titanium dioxide, aluminum hydroxide, calcium sulfate, and amorphous silicate. The inorganic filler may be, for example, calcium carbonate. The calcium carbonate can be an anionic calcium carbonate, such as anionic ground calcium carbonate or anionic precipitated calcium carbonate, or it can be a cationic calcium carbonate, such as cationic precipitated calcium carbonate or cationic ground calcium carbonate. .

  The organic filler can be selected from the group consisting of synthetic polymer fillers, starch-based fillers, wood powder fillers, or any combination thereof. Synthetic polymer fillers may be, for example, 1,1-dichloroethylene / acrylonitrile copolymers, urea formaldehyde resin aggregate fillers and starch-based fillers. The papermaking filler is, for example, selected from the group consisting of calcium carbonate, kaolin, talc, titanium dioxide, aluminum hydroxide, calcium sulfate, amorphous silicate, polymer filler, starch filler and wood powder filler. 1 type or the combination of 2 or more types may be sufficient. The papermaking filler may be either surface unmodified or surface modified. Surface modification can be performed by conventional surface modifiers in the art, such as raw starch, cationic starch.

  “Paper filler particles” refers to paper filler particles that are not subjected to surface modification. The papermaking filler particles may be primary particles (individual papermaking filler particles) or secondary particles (aggregates of papermaking filler particles). The particle size of the papermaking filler particles is not particularly limited as long as it does not affect the use as a papermaking filler. The particle size of the papermaking filler particles may be, for example, 0.1 to 200 μm, for example 2 to 100 μm, for example 10 to 50 μm.

  “Coating layer” refers to a layer covering the surface of the core. The weight ratio of the coating layer to the core may be, for example, 0.1: 100 to 5: 100, such as 0.2: 100 to 2: 100, or such as 0.3: 100 to 1.5: 100.

  Paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide can be produced by the following method. The manufacturing method includes the following steps:

  1. Preparing a solution or dispersion of a hydroxyl-containing hydrocarbon natural polymeric polysaccharide. The solution or dispersion may be, for example, an aqueous solution or an aqueous dispersion. There is no particular limitation on the content of the hydroxyl-containing hydrocarbon natural polymer polysaccharide in the solution or dispersion, which can be suitably selected according to actual needs, such as 0.1 to 20% by weight, or, for example, It may be 0.2 to 10% by weight, or for example 0.5 to 5% by weight.

  2. Preparing a suspension of papermaking filler particles. The suspension may be an aqueous suspension. There is no special restriction | limiting in the content rate of the papermaking filler particle | grains in suspension, It can select suitably according to actual need. For example, the content of papermaking filler particles in the suspension may be 1 to 60 wt%, or such as 5 to 30 wt%, or such as 10 to 20 wt%.

  3. Mix the solution or dispersion of the hydroxyl-containing hydrocarbon natural polymer polysaccharide with the suspension of the paper-made filler particles so that the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound coats the surface of the paper-made filler particles. Step. The mixing ratio of the solution or dispersion of the hydroxyl-containing hydrocarbon natural polymer polysaccharide to the suspension of the paper filler particles is not particularly limited and can be suitably selected according to actual needs. For example, the hydroxyl-containing hydrocarbon natural polymer polysaccharide in the solution or dispersion of the hydroxyl-containing hydrocarbon natural polymer polysaccharide is 0 with respect to 100 parts by weight of the paper-making filler particle in the suspension of paper filler particles. 0.1-20 parts by weight, or for example 0.2-10 parts by weight, or for example 0.5-5 parts by weight. During and / or after mixing, mixing can be facilitated, for example, by stirring. The resulting liquid can be used directly as a paper filler and the prepared paper filler particles modified with hydroxyl-containing hydrocarbon natural polymeric polysaccharide compounds can also be filtered and / or centrifuged. It can be separated by means such as separation. The weight ratio of the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound to the paper-making filler particles in the prepared paper-made filler particles modified with the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is determined as follows. It can be adjusted by adjusting the mixing ratio, mixing period, stirring conditions, and filtration / centrifugation conditions of the solution or dispersion of the molecular polysaccharide compound and the suspension of the papermaking filler particles.

  The weight ratio of the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound to the paper filler particles in the paper-made filler particles modified with the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound can be measured, for example, by the following method: The resulting paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound are dried, for example, by heating, the contained medium (for example, water, organic solvent) is removed, and then calibrated. M1; Heat-dried paper-made filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound are re-immersed in a medium (for example, water or an organic solvent) to rehydrate the hydroxyl-containing hydrocarbon natural polymer polysaccharide. The compound layer is swollen and then the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound layer is physically treated (eg The resulting paper filler particles are dried again, for example by heating, to remove the adhering medium and then weighed again to indicate M2; weight ratio Is M1-M2 / M2. For example, when the paper filler particles are flammable inorganic fillers such as calcium carbonate, the weight ratio can be measured by the following method: modified by the resulting hydroxyl-containing hydrocarbon natural polymer polysaccharide compound The papermaking filler particles are separated by filtration, dried at, for example, 120 ° C. to remove the medium (eg, water, organic solvent), and a certain amount of completely dried hydroxyl-containing hydrocarbon natural polymer polysaccharide compound The papermaking filler particles modified by the above are taken, weighed and shown as M1; heated in air at 550 ° C. for 2 hours, weighed again and shown as M2; the weight ratio is M1-M2 / M2 .

Papermaking method (process)
The “papermaking method (process)” or “method for papermaking” includes the steps of forming an aqueous cellulosic papermaking furnish, draining the furnish to form a sheet, and drying the sheet Is intended to mean a method of manufacturing a paper product.

  “Pulp slurry” or “pulp” is intended to mean a product obtained from a pulping process. “Pulping” is a chemical method or mechanical method or a combination of both, where plant fiber raw materials are dissociated to form a pulp slurry with the original color (unbleached pulp), or further bleached pulp is formed. Includes manufacturing processes. The pulp can be any of the known pulps, including mechanical pulp, chemical pulp, chemical-mechanical pulp, and recycled waste paper pulp slurry, such as pulp containing mechanical pulp and / or recycled fiber However, it is not limited to these.

  The pulp is subjected to pulping and additional conditioning to produce a suspension of fibers that can be used in a hand sheet. Such fiber suspensions are referred to as “paper stocks” to distinguish them from paper slurries that are not subject to pulping and additional conditioning.

  “Wet paper sheet” refers to the product obtained after the pulp raw material is formed through the headbox, molding part and press part and partially drained, and the wetness of the wet paper sheet is, for example, 35% May be in the range of 50% to 50%. For the sake of clarity, the product that comes from the molding part but has not been used for draining in the press part is called “wet paper web”. The dryness of the wet paper web may be in the range of 15% to 25%, for example.

  “Paper sheet” refers to the product obtained after the wet paper sheet has been dried in the dryer section. The dryness of the paper sheet may be in the range of 92% to 97%, for example.

In one aspect, the present invention further comprises
(A) preparing a pulp slurry;
(B) At the same time before or after the ASA emulsion emulsified with the polymer emulsifier is added to the pulp slurry, the filler particles for papermaking modified with the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound are added to the pulp slurry. And get paper stock,
(C) molding the resulting stock to obtain a wet paper web;
(D) pressing and draining the wet paper web obtained in step (c) to obtain a wet paper sheet;
(E) drying the wet paper sheet obtained in step (d) to obtain a paper sheet.

1. The process before flowing on the wire includes the following steps:
(1) Steps to prepare stock: paper slurry can be made into stock, and stock preparation is pulping and additional adjustment (sizing agent, filler, pigment and auxiliary agent) Etc.) are added. The paper slurry is first subjected to pulping, where the fibers of the paper slurry are required for certain types of paper and to provide the paper with physical and mechanical properties that meet the requirements of the paper machine. , Undergo necessary processing such as cutting, swelling, and fine fiber formation. Paper slurry is useful for writing and imparting resistance to liquid impregnation, improving paper color, whiteness and color tone, increasing paper transparency, improving paper printing performance, etc. Size, filler addition, and coloring. In addition, various chemical auxiliaries can be added to impart some special properties to the paper, such as enhanced dry and wet paper strength, and foam removal. At this stage, some or all of the papermaking filler particles modified by the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound can be added to the paper slurry as a filler. Independently, at the same time or before or after, some or all of the ASA emulsion emulsified with the polymer emulsifier can be added as a sizing agent into the paper slurry. As a filler, only paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound may be added to the paper slurry; and / or as a sizing agent, the paper slurry is emulsified with a polymer emulsifier. Only an ASA emulsion may be added. Obviously, other fillers and / or sizing agents can be added into the paper slurry as required.

  (2) Supplying the stock to the slurry supply system: The stock is supplied into the slurry supply system and subjected to processing such as storage, screening, purification, slag removal, sand removal, gas removal, etc., and metal impurities, Non-metallic impurities, fiber bundles, lumps and air are discharged to avoid adverse effects on paper quality and not interfere with the papermaking process. The slurry is adjusted for slurry proportion, dilution rate, concentration, drug addition and pressure removal, and then flows into the headbox and onto the wire for papermaking.

2. Paper making includes the following steps:
(1) Step of approaching the raw material flow: The stock is delivered to the forming part (wire part) through the head box. The headbox is useful for uniformly dispersing the fibers and allowing the slurry to flow smoothly over the wire. Papermaking additives, such as dry strength agents, wet strength agents, can be added in the process of approaching the feed stream. At this stage, some or all of the papermaking filler particles modified by the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound can be added to the paper slurry as a filler. Independently, at the same time or before or after, some or all of the ASA emulsion emulsified with the polymer emulsifier can be added as a sizing agent into the paper slurry. As a filler, only paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound may be added to the paper slurry; and / or as a sizing agent, the paper slurry is emulsified with a polymer emulsifier. Only an ASA emulsion may be added. Obviously, other fillers and / or sizing agents may be added into the paper slurry as required.

  (2) Molding step: In the molding part, the stock delivered by the molding part is molded into a wet paper web by draining on the wire. The molded part is also referred to as a wire part. The dryness of the wet paper web may be in the range of 15% to 25%, for example.

  Step (c) may be performed by step (1) or (2), but is not limited thereto.

  (3) Pressing and draining step: In the pressing part, the wet paper web from the forming part is subjected to a mechanical press to form a wet paper sheet. The dryness of the wet paper sheet may be in the range of 35% to 50%, for example.

  Step (d) can be performed by, for example, step (3), but is not limited thereto.

  (4) Drying step: In the dryer section, the wet paper sheet from the press section is dried in a drying cylinder to form a paper sheet. The dryness of the paper sheet may be in the range of 92% to 97%, for example.

  Step (e) can be performed by, for example, step (4), but is not limited thereto.

  The amount of papermaking filler particles modified by the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound added to the paper slurry can be suitably selected as required by those skilled in the art, for example, the final paper (When the particles are added in several stages, the amount refers to the total amount). For example, the total amount of paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is, for example, 1 to 50 parts by weight or, for example, 10 to 30 parts by weight with respect to 100 parts by weight of the overdried pulp slurry. Or for example 15-30 parts by weight, or for example 20-30 parts by weight. The sizes in the above two stages are called internal sizes and this method of size is the method used in the papermaking process. The amount of ASA emulsion added by emulsification with the polymer emulsifier can be suitably selected as required by those skilled in the art, and such selection is a common skill for skilled technicians (emulsion When added in several stages, the amount refers to the total amount). The ASA emulsion emulsified with the polymer emulsifier is in an amount based on ASA with respect to 100 parts by weight of the overdried pulp slurry, for example, 0.05 to 0.5 parts by weight, for example 0.05 to 0.1 parts by weight. Can be added in an amount.

  In addition, the paper sheet may be subjected to finishing processes such as calendaring, winding and cutting, paper sorting or rewinding, packaging, etc., as necessary, to produce the paper sheet into a finished paper in the form of a flat or roll. You may go. In addition, surface size, coating, and on-line soft calender or off-line super calender can be implemented in the dryer section to improve paper sheet quality.

  In the papermaking process, the paper slurry provided by the stock preparation system is generally supplied to the slurry supply system (which is treated before the stock flows on the wire), the head box and the molding unit, the press unit, the dryer unit, etc. Provided.

  The invention is described in more detail by reference to the following examples and comparative examples, but is not limited to these examples.

1. Preparation of cooked starch or other hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds For use as hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds, it is necessary to cook starch (either raw starch or cationic starch) is there. A starch paste was formed by cooking a quantity of starch in water. The starch paste concentration was 2% by weight. For other hydroxyl-containing hydrocarbon natural polymeric polysaccharide compounds, a 1% strength by weight solution or dispersion was formulated at room temperature and stored for future use.

2. Preparation of paper-made filler particles modified with hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds by coating paper-made filler particles with cooked starch or other hydroxyl-containing hydrocarbon natural polymer polysaccharide compounds. The calcium suspension was placed in a beaker and a certain amount of hydroxyl-containing hydrocarbon natural polymeric polysaccharide compound was added into the calcium carbonate particles with stirring for 10 minutes. After the addition of the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound, the particle size of the calcium carbonate particles increased significantly.

3. Preparation of ASA emulsion emulsified with polymer emulsifiers 0.0175 g N7541 or N63007 (both are Nalco products) are mixed with 50-99.9 g water, then added into 0.01-40 g ASA, high Stir for 1-2 minutes under shear conditions to obtain an ASA emulsion for size.

4). Laboratory papermaking and paper water resistance testing Fiber slurry composition: 20% softwood bleached kraft pulp (NBKP), 20% hardwood bleached kraft pulp (LBKP), 20% bleached chemithermomechanical pulp (BCTMP) ).

  A certain amount of fiber slurry was mixed with a corresponding amount of pretreated filler. After mixing for 5 seconds, the wet end starch was added, followed by the ASA emulsion emulsified with the polymer 15 seconds after mixing the fiber slurry and pretreated filler. Ten seconds after adding the ASA emulsion, Nalco product N-61067 was added as a retention aid and mixed for an additional 15 seconds. Agitation was discontinued and the furnish mixture was transferred to Rapid Kosten Sheet Former for sheeting. The blending ratio of the slurry used for papermaking was 20-30 parts by weight of calcium carbonate filler treated with a polysaccharide compound with respect to 100 parts by weight of the slurry added. As a control, untreated calcium carbonate filler was also used as a filler and added to the fiber slurry for papermaking. After draining through a 100 mesh line, a 20 cm diameter paper sheet was formed. The paper sheet was then dried under vacuum at 96 ° C. for 8 minutes and cured overnight at 24 ° C. under constant temperature conditions.

  The water resistance of the paper sample is tested by Hercules sizing test (Hercules Sizing Test (HST)). The HST method is an optical method that measures the resistance of paper to penetration of an aqueous penetrant and is a general purpose test useful for the degree of size. The penetration time of the test ink in the paper is used to evaluate the water resistance of the paper. The ink used in the experiment contains 1% formic acid (see Tappi Official Method 530).

5. Experimental results and data analysis [Example 1]
Cationic chitosan solution (concentration 1%) was added with stirring into a certain amount of anionic calcium carbonate suspension and further stirred for about 20 minutes. The average particle size of calcium carbonate was 1.9 μm before the treatment and increased to about 7 to 10 μm after the treatment with the cationic chitosan solution. The weight ratio of cationic chitosan to calcium carbonate in the particles was measured from about 0.3: 100 to 1.5: 100. The treated calcium carbonate suspension was added to the pulp slurry and used for the sheet according to step 4 above. The ASA emulsifier used for the sheet is Nalco product N7541, which has the structure of a copolymer of methylacryloyloxyethyltrimethylammonium chloride and acrylamide and contains 10 mol% cationic charge [DMAEM ^* MCQ (Dimethylammonium methyl methacrylate methyl chloride quat) / AcAm (acrylamide)]. Calcium carbonate accounted for about 27-30% of the weight of the final paper, i.e. about 27-30 parts by weight of 100 parts by weight of pulp slurry with filler was calcium carbonate. The amount of ASA used in the hand sheet manufacturing process, the amount of cationic chitosan used for the treatment of the CaCO ₃ filler, the particle size of the filler before and after the treatment, the HST result, and the ash content of the final paper sheet Table 1 summarizes.

From the above data it can be seen that pretreatment of CaCO ₃ filler with cationic chitosan helps to improve the size efficiency of ASA emulsion emulsified with polymer. For example, when calcium carbonate is untreated, filler is added in an amount of about 28-29% by weight and ASA is added in an amount of 0.5 kg / ton, the HST value of a paper sample obtained from the papermaking process Is 2.8 s, and after treating the filler with cationic chitosan at a usage rate of 15 kg / ton, the HST value rises to 26.5 s. When calcium carbonate is untreated, filler is added in an amount of about 28-29% by weight, and ASA is added in an amount of 0.9 kg / ton, the HST value of the paper sample obtained from the papermaking process is 36. .1 s, and after treating the filler with cationic chitosan at a usage rate of 15 kg / ton, the HST value rises to 177.0 s.

[Example 2]
Guar gum solution (concentration 1%, cationic substitution degree 0.04) was added with stirring into a certain amount of anionic calcium carbonate suspension and stirred for about 20 minutes. The average particle size of calcium carbonate was 1.9 μm before the treatment, and increased to about 9-30 μm depending on the amount of guar gum used. The weight ratio of cationic chitosan to calcium carbonate in the particles was measured from about 0.3: 100 to 1.5: 100. The treated calcium carbonate suspension was added to the pulp slurry and used for the sheet according to Step 4 above. The ASA emulsifier used for the sheet was Nalco product N7541. Calcium carbonate accounted for about 30% of the weight of the final paper, i.e., about 30 parts by weight of 100 parts by weight of pulp slurry with filler was calcium carbonate. The amount of ASA used in the hand sheet manufacturing process, the amount of cationic guar gum used for the treatment of the CaCO ₃ filler, the particle size of the filler before and after the treatment, the HST result, and the ash content of the final paper sheet These are summarized in Table 2.

  From the above data it can be seen that pretreatment of calcium carbonate with cationic guar gum helps to improve the size efficiency of ASA emulsion emulsified with polymer. For example, when calcium carbonate is untreated, filler is added in an amount of about 28 to 29% by weight, and ASA is added in an amount of 0.6 kg / ton, the HST value of a paper sample obtained from the paper making process Is 4.5 s, and after treating the filler with cationic guar gum at a usage rate of 15 kg / ton, the HST value rises to 32.7 s. When calcium carbonate is untreated, filler is added in an amount of about 28-29% by weight, and ASA is added in an amount of 1.0 kg / ton, the HST value of the paper sample obtained from the papermaking process is 15 .5 s, and after treating the filler with cationic guar gum at a usage rate of 15 kg / ton, the HST value rises to 143.1 s.

[Example 3]
The cooked cationic starch solution (concentration 2%) was added with stirring into a certain amount of anionic calcium carbonate suspension and further stirred for about 20 minutes. The average particle size of calcium carbonate was 1.9 μm before treatment and increased to about 100 μm after treatment with starch solution. The weight ratio of cationic chitosan to calcium carbonate in the particles was measured from about 0.3: 100 to 1.5: 100. The treated calcium carbonate suspension was added to the pulp slurry for papermaking. Calcium carbonate accounted for about 30% of the weight of the final paper, i.e., about 30 parts by weight of 100 parts by weight of pulp slurry with filler was calcium carbonate. The composition of the fiber pulp slurry was NBKP 20%, LBKP 60% and BCTMP 20%, and the paper basis weight was 100 g / m ² . The polymer emulsifier used in the experiment was Nalco product N63007. Table 3 shows the test data for water resistance.

From the above data it can be seen that pretreatment of CaCO ₃ filler with cooking cationic starch helps to improve the size efficiency of ASA emulsion emulsified with polymer. For example, when calcium carbonate is untreated, filler is added in an amount of about 28 to 29% by weight, and ASA is added in an amount of 0.5 kg / ton, the HST value of a paper sample obtained from the papermaking process Is 6.2 s, and the HST value rises to 110.2 s after treating the filler with cooking cationic starch at a usage rate of 15 kg / ton. When calcium carbonate is untreated, filler is added in an amount of about 28-29% by weight, and ASA is added in an amount of 0.9 kg / ton, the HST value of the paper sample obtained from the paper making process is 68. .3 s, the HST value rises to 395.6 s after treating the filler with cooking cationic starch at a usage rate of 15 kg / ton.

[Example 4]
The cooked raw starch solution (concentration 2%) was added with stirring into a certain amount of anionic calcium carbonate suspension and stirred for about another 20 minutes. The average particle size of calcium carbonate was 2 μm before treatment and increased to about 17-50 μm depending on the amount of starch used in the treatment solution. The weight ratio of cationic chitosan to calcium carbonate in the particles was measured from about 0.3: 100 to 1.5: 100. The treated calcium carbonate suspension was added to the pulp slurry for papermaking. Calcium carbonate accounted for about 28-30% of the weight of the final paper, ie, about 28-30 parts by weight of 100 parts by weight of the pulp slurry with filler was calcium carbonate. The composition of the fiber pulp slurry was NBKP 20%, LBKP 60% and BCTMP 20%, and the paper basis weight was 100 g / m ² . The polymer emulsifier used in the experiment was Nalco product N63007. Table 4 shows the test data for water resistance.

  From the above data it can be seen that pretreatment of calcium carbonate with uncooked raw starch helps to improve the size efficiency of ASA emulsion emulsified with polymer. For example, when calcium carbonate is untreated, filler is added in an amount of about 28 to 29% by weight, and ASA is added in an amount of 0.5 kg / ton, the HST value of a paper sample obtained from the papermaking process Is 2.6 s, and the HST value rises to 122.1 s after treating the filler with cooking cationic starch at a usage rate of 15 kg / ton. When calcium carbonate is untreated, filler is added in an amount of about 28-29% by weight, and ASA is added in an amount of 0.9 kg / ton, the HST value of the paper sample obtained from the papermaking process is 16 .3 s, the HST value rises to 240.5 s after the filler is treated with cooking cationic starch at a usage of 15 kg / ton.

[Example 5]
Compare with the case of using starch as an emulsifier Cationic starch is one of the most commonly used effective emulsifiers used in ASA sizes. The purpose of this example is to compare the size efficiency of 7541 as an emulsifier when the filler is pretreated with cooked starch to the size efficiency when using cationic starch directly as an emulsifier. In the experiment, the calcium carbonate filler was pretreated with cooked starch when 7541 was used as the emulsifier. The amount of raw cooked starch used to pre-treat the filler was 10 kg of cooked starch per ton of filler. US Pat. No. 5,411,639 discloses the use of starch and sodium stearylcarboxylate in the treatment of calcium carbonate fillers to improve size efficiency. In this experiment, the effect of calcium carbonate on ASA size efficiency is compared and calcium carbonate is treated with a complex formed by adding sodium stearylcarboxylate into the cooked starch. Experiments have found that cooked starch worked to improve the size efficiency of ASA emulsified with polymer, more effectively than the cooked starch-sodium stearylcarboxylate complex by the filler treatment approach. N7541 worked more effectively as an emulsifier when the filler was pretreated than cooked starch without the filler being pretreated.

[Example 6]
Effect of CaCO _{3 at} different contents This example compared the effect of fillers treated with starch on the size efficiency of the polymer emulsifier at different filler usage. The starch used was cooking uncationized raw starch. The composition of the fiber pulp slurry used was 20% NBKP, 60% LBKP and 20% BCTMP, the paper basis weight was 100 g / m ² , and the polymer emulsifier used in the experiment was Nalco product N7541 there were.

  From Table 6, it can be seen that the size efficiency of ASA decreases with increasing filler loading, while the size efficiency of ASA improves with increasing the amount of starch used to treat calcium carbonate.

Claims (24)

A method for improving the size efficiency of an ASA emulsion emulsified with a polymer emulsifier in a papermaking process, comprising:
Sizing the pulp slurry by using an ASA emulsion emulsified with the polymer emulsifier as a sizing agent;
Adding a papermaking filler particle modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound into the pulp slurry as a papermaking filler;
Including the method.   The hydroxyl-containing hydrocarbon natural polymer polysaccharide is selected from the group consisting of cooked cationic starch, cooked natural starch, cellulose, cationic cellulose, chitosan, cationic chitosan, guar gum and cationic guar gum, or any combination thereof. The method according to claim 1.   The method of claim 1, wherein the papermaking filler particles are calcium carbonate particles.   The method of claim 1, wherein the polymer emulsifier is selected from the group consisting of copolymers of acrylamide and cationic monomers, and copolymers of acrylamide and cationic monomers cross-linked with glyoxal.   The polymer emulsifier is a copolymer of acrylamide and a cationic monomer having a weight average molecular weight of 10,000 to 1,000,000 daltons, and the ratio of the cationic monomer unit to the acrylamide unit is 1/99. 5. The method of claim 4, wherein the method is between 20/80, between 2/98 and 18/82, or between 5/95 and 15/85.   The polymer emulsifier is a copolymer of glyoxal cross-linked acrylamide and a cationic monomer having a weight average molecular weight of 100,000 to 3,000,000 daltons, wherein the ratio of the acrylamide unit to the cationic monomer unit is The ratio of the glyoxal units to the acrylamide units is between 60/40 and 5/95, between 50/50 and 10/90, or 45/55 and 10 The method of claim 4, which is between / 90.   The cationic monomer is dimethyldiallylammonium chloride, methylacrylyloxyethyltrimethylammonium chloride, N, N, N-trimethyl-3- (2-methylallylamido) -1-propylammonium chloride, N, N′-dimethyl. Aminoethyl methacrylate, quaternary ammonium salt cation of N, N′-dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, quaternary ammonium salt of dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and quaternary ammonium of diethylaminoethyl acrylate The method according to any one of claims 4 to 6, which is selected from the group consisting of salts.   5. The method of claim 4, wherein the polymeric emulsifier is selected from the group consisting of glyoxal cross-linked dimethyldiallylammonium chloride acrylamide and a copolymer of methylacrylyloxyethyltrimethylammonium chloride and acrylamide.   The weight ratio of the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound to the paper filler particle in the paper-made filler particles modified with the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is from 0.1: 100. The method of claim 1, wherein the method is 5: 100, 0.2: 100 to 2: 100, or 0.3: 100 to 1.5: 100. A method for papermaking,
(A) preparing a pulp slurry;
(B) Simultaneously or before or after addition of the ASA emulsion emulsified with a polymer emulsifier into the pulp slurry, paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound are added to the pulp slurry. Adding to and obtaining a stock,
(C) molding the resulting stock to obtain a wet paper web;
(D) pressing and draining the wet paper web obtained in step (c) to obtain a wet paper sheet;
(E) drying the wet paper sheet obtained in step (d) to obtain a paper sheet;
Including methods.   The hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is selected from the group consisting of cooked cationic starch, cooked natural starch, cellulose, cationic cellulose, chitosan, cationic chitosan, guar gum and cationic guar gum, or any combination thereof 11. The method of claim 10, wherein:   The method of claim 10, wherein the papermaking filler particles are calcium carbonate particles.   11. The method of claim 10, wherein the polymeric emulsifier is selected from the group consisting of a copolymer of acrylamide and a cationic monomer, and a copolymer of acrylamide and a cationic monomer cross-linked with glyoxal.   The polymer emulsifier is a copolymer of acrylamide and a cationic monomer having a weight average molecular weight of 10,000 to 1,000,000 daltons, and the ratio of the cationic monomer unit to the acrylamide unit is 1/99. 14. A method according to claim 13, which is between 20/80, between 2/98 and 18/82, or between 5/95 and 15/85.   The polymer emulsifier is a copolymer of glyoxal cross-linked acrylamide and a cationic monomer having a weight average molecular weight of 100,000 to 3,000,000 daltons, wherein the ratio of the acrylamide unit to the cationic monomer unit is The ratio of the glyoxal units to the acrylamide units is between 60/40 and 5/95, between 50/50 and 10/90, or 45/55 and 10 14. The method of claim 13, wherein the method is between / 90.   The cationic monomer is dimethyldiallylammonium chloride, methylacrylyloxyethyltrimethylammonium chloride, N, N, N-trimethyl-3- (2-methylallylamido) -1-propylammonium chloride, N, N′-dimethyl. Aminoethyl methacrylate, quaternary ammonium salt cation of N, N′-dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, quaternary ammonium salt of dimethylaminoethyl acrylate, diethylaminoethyl acrylate, and quaternary ammonium of diethylaminoethyl acrylate 16. A method according to any one of claims 13 to 15 selected from the group consisting of salts.   14. The method of claim 13, wherein the polymeric emulsifier is selected from the group consisting of glyoxal cross-linked dimethyl diallylammonium chloride acrylamide and a copolymer of methyl acrylyloxyethyl trimethyl ammonium chloride and acrylamide.   The weight ratio of the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound to the paper filler particles in the paper-made filler particles modified with the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is 0.1: 100 to 5: 11. The method of claim 10, wherein the method is 100, 0.2: 100 to 2: 100, or 0.3: 100 to 1.5: 100.   The total addition amount of the paper filler particles modified with the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound is 1 to 50 parts by weight, or 10 to 30 parts by weight, or 100 parts by weight of the overdried pulp slurry, or The method of Claim 10 which is 15-30 weight part or 20-30 weight part.   The ASA emulsion emulsified with the polymer emulsifier is in an amount based on ASA, in an amount of 0.05 to 0.5 parts by weight, or 0.05 to 0.1 parts by weight, with respect to 100 parts by weight of the overdried pulp slurry. The method according to claim 10, which is added. Paper filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound,
A core made of individual papermaking filler particles, or aggregates of papermaking filler particles;
A coating layer covering the surface of the core and formed by the hydroxyl-containing hydrocarbon natural polymer polysaccharide;
Including
The weight ratio of the hydroxyl-containing hydrocarbon natural polymer polysaccharide to the paper filler particles is 0.1: 100 to 5: 100, 0.2: 100 to 2: 100, or 0.3: 100 to 1.5. : 100 papermaking filler particles.   The hydroxyl-containing hydrocarbon natural polymer polysaccharide is selected from the group consisting of cooked cationic starch, cooked natural starch, cellulose, cationic cellulose, chitosan, cationic chitosan, guar gum and cationic guar gum, or any combination thereof. The paper filler particle modified by the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound according to claim 21.   The papermaking filler particles modified with a hydroxyl-containing hydrocarbon natural polymer polysaccharide compound according to claim 21, wherein the papermaking filler particles are calcium carbonate particles.   24. The paper-containing filler particles for improving the size efficiency of an ASA emulsion emulsified with a polymer emulsifier in papermaking are produced by the hydroxyl-containing hydrocarbon natural polymer polysaccharide compound according to any one of claims 21 to 23. Use of modified paper filler particles.