EP0953679A1 - Paper strengthening agent and paper strengthening method - Google Patents
Paper strengthening agent and paper strengthening method Download PDFInfo
- Publication number
- EP0953679A1 EP0953679A1 EP98111753A EP98111753A EP0953679A1 EP 0953679 A1 EP0953679 A1 EP 0953679A1 EP 98111753 A EP98111753 A EP 98111753A EP 98111753 A EP98111753 A EP 98111753A EP 0953679 A1 EP0953679 A1 EP 0953679A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- paper
- polymer
- dispersion
- paper strengthening
- diluted
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/18—Reinforcing agents
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
- D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
- D21H17/43—Carboxyl groups or derivatives thereof
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/50—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by form
- D21H21/52—Additives of definite length or shape
Definitions
- the present invention relates to a paper strengthening agent comprising a dispersion of fine water-insoluble polymer particles manufactured by polymerizing a monomer containing (meth)acrylic acid in an aqueous solution and precipitating the produced polymer, which is added to a paper layer after a paper layer is formed in a paper making process and relates to a paper strengthening method wherein a low-viscosity polymer dispersion prepared by diluting the present paper strengthening agent with water is impregnated into paper by spraying or coating.
- the Laid-Open Japanese Patent Application No. Sho 62-20511 discloses a method of obtaining a water-soluble polymer dispersion by polymerizing a monomer in an aqueous salt solution that dissolves the monomer and does not dissolve a formed polymer in the presence of a polymer electrolyte.
- the Laid-open Japanese Patent Application No. Sho 60-185900 discloses a method for obtaining a dispersion of fine polymer particles by polymerizing acrylic acid with acrylamide in an aqueous salt solution that dissolves the monomers but does not dissolve the formed polymer.
- the fine particles can be obtained in the absence of any polymer electrolyte.
- the fine polymer particles obtained here are water-insoluble and dissolved in a solvent if the dispersion is neutralized. That is, it is a different technique from that proposed in the Laid-open Japanese Patent Application No. Sho 62-20511.
- the fine particles in the dispersion of acrylic acid-acrylamide copolymer agglomerate on standing resulting in curding in the manner of bean curd, thereby having the disadvantage of being unable to be stored for long periods of time.
- An object of the present invention is to increase bursting strength, ring crush strength and surface paper strength such as wax pic by efficiently impregnating a paper layer with a high molecular weight polymer.
- Another object of the present invention is to increase the interlayer adhesive paper strength by adhering a high molecular weight polymer to a plurality of web surfaces.
- a dispersion of fine polymer particles having a low viscosity, good workability and excellent stability for preservation can be manufactured by polymerizing a monomer containing (meth)acrylic acid in the presence of a dispersibility retaining agent such as a cationic polymer electrolyte to precipitate the produced polymer.
- the inventors of the present invention also discovered that said dispersion demonstrates outstanding effects such as paper strengthening by coating said dispersion onto dry paper with a size press, gate roll coater or blade coater and so forth, paper strengthening by spray impregnating said dispersion into wet paper on a wire part, and interlayer adhesion paper strengthening by adhering a polymer of said dispersion onto a plurality of web surfaces, thereby leading to completion of the present invention.
- a first aspect of the present invention is to provide a paper strengthening agent substantially comprising a polymer dispersion manufactured by polymerizing a monomer containing (meth)acrylic acid in an aqueous solution and precipitating the produced polymer as fine particles, and which is added to a paper layer after a paper layer is formed, wherein
- a second aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the polymer dispersion is polymerized and precipitated in the presence of a dispersibility retaining agent comprising a polyvalent electrolyte.
- a third aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is one selected from a cationic polymer electrolyte, a surface active agent having a polyvalent cationic hydrophilic group and a hydrophobic group, and a mixture thereof.
- a fourth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the weight ratio of the monomer containing (meth)acrylic acid in an aqueous solution to the dispersibility retaining agent is 100:1 to 10:1.
- a fifth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the viscosity of said polymer dispersion is 30 to 1500 mPa ⁇ s immediately after and one month after the production.
- a sixth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is dimethyldiallylammonium chloride (co)polymer.
- a seventh aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is an alkyl group-substituted and/or an aralkyl group-substituted polyethylenepolyamine.
- An eighth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is an alkyl group having at least 5 carbon atoms-substituted and/or an aralkyl group-substituted pentaethylenehexamine.
- a ninth aspect of the present invention is to provide a paper strengthening method comprising the steps of: diluting the above-mentioned paper strengthening agent with water to prepare a diluted dispersion, coating or impregnating said diluted dispersion onto a dry paper, and drying the treated dry paper.
- a tenth aspect of the present invention is to provide a paper strengthening method wherein a diluted dispersion of the above-mentioned paper strengthening agent is impregnated into wet paper.
- An eleventh aspect of the present invention is to provide a paper strengthening method wherein a diluted dispersion of the above-mentioned paper strengthening agent is spray impregnated into wet paper.
- a twelfth aspect of the present invention is to provide a paper strengthening method wherein the wet paper in the above method is of a single layer.
- a thirteenth aspect of the present invention is to provide a method of preventing interlayer separation comprising the steps of spraying a diluted dispersion of the above-mentioned paper strengthening agent onto a web surface to prepare a plurality of webs having a polymer adhered to surfaces thereof, and pressing the surfaces of said webs so as to be superimposed followed by drying.
- the monomer that contains (meth)acrylic acid used in the present invention is a mixture of 5 to 50 mol% of acrylic acid, methacrylic acid or a mixture thereof, and itaconic acid and/or acryloylaminoisobutyl sulfonic acid and so forth over a range that does not lower the degree of polymerization or have a detrimental effect on solubility; and, 50 to 95 mol% of one type of nonionic monomer selected from the group consisting of (meth)acrylamide, (meth)acrylonitrile, N-vinylcarboxylic amide, N-isopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, methyl(meth)acrylate, hydroxyethyl(meth)acrylate, vinylmethylether, vinylacetate, styrene and a mixture thereof.
- Cationic monomer can be polymerized as a component of the monomer containing (meth)acrylic acid over the range in which water insolubility of the resulted polymer can be secured when diluting with distilled water.
- a monomer composition that contains 5 to 50 mol% of (meth)acrylic acid, 50 to 95 mol% of (meth)acrylamide and 0 to 50 mol% of (meth)acrylonitrile is most preferable.
- dispersibility retaining agent comprising a cationic polymer electrolyte used in the present invention are (co)polymers of salts or quaternary products of dialkylaminoalkyl(meth)acrylate, (co)polymers of salts or quaternary products of dialkylaminoalkyl(meth)acrylamide, and (co)polymers of dialkyldiallylammonium salt.
- Examples of the salts or quaternary products of dialkylaminoalkyl(meth)acrylate include dimethylaminoethyl(meth)acrylate hydrochloride and acryloyloxyethyltrimethylammonium chloride.
- examples of the salts or quaternary products of the dialkylaminoalkyl(meth)acrylamide include hydrochlorides or methylated products of dialkylaminopropyl(meth)acrylamide.
- An example of dialkyldiallylammonium salt is dimethyldiallylammonium chloride.
- the cationic water-soluble polymer may be a homopolymer or a copolymer with a nonionic monomer such as acrylamide.
- a particularly preferable cationic water-soluble polymer is dimethyldiallylammonium chloride (co)polymer.
- An example of a dispersibility retaining agent comprising a surface active agent having a polyvalent cationic hydrophilic group and a hydrophobic group used in the present invention is a substituted polyethylenepolyamine in which at least one hydrogen atom at a nitrogen atom thereof is substituted by an alkyl group and/or an aralkyl group.
- An alkyl group-substituted product of pentaethylenehexamine having at least 5 carbon atoms in said alkyl group is effective.
- the weight ratio of the monomer that contains (meth)acrylic acid to the dispersibility retaining agent is preferably 100:1 to 10:1. If the amount of the dispersibility retaining agent is too small, the dispersion curds into the form of bean curd. On the other hand, excessive addition of dispersibility retaining agent is economically meaningless.
- the dispersibility retaining agent according to present invention may be a sole compound or a mixture thereof.
- the viscosity of the polymer dispersion is maintained within the range of 30 to 5000 mPa ⁇ s immediately after and one month after the production, and is stable for a long time.
- a product having a viscosity of 30 to 1500 mPa ⁇ s is preferable in terms of handling when considering convenience during use.
- the surface charge of the polymer particles is considered to be cationic, and it can also be mixed with an aqueous solution of a water-soluble cationic polymer and an aqueous dispersion.
- An aqueous salt solution may also be used in the present invention for the purpose of promoting polymer precipitation.
- the salt that forms said aqueous salt solution include alkaline metal salts such as sodium salt and potassium salt, and ammonium salts such as ammonium chloride, ammonium sulfate and ammonium nitrate.
- the concentration and pH of said aqueous salt solution must be such that the monomers containing (meth)acrylic acid dissolve, while the polymer that is formed does not. In contrast, it is necessary that the dispersibility retaining agent that is also present be soluble in said aqueous salt solution.
- the (meth)acrylic acid (co)polymer dispersion and the dispersibility retaining agent in the present invention can respectively be obtained by dissolving monomer(s) in an aqueous medium under nitrogen atmosphere without oxygen, and radical polymerizing the monomer(s) by adding a water-soluble azo type polymerization initiator such as 2,2'-azobis(2-amidinopropane) hydrochloride or a water-soluble redox type polymerization initiator using such as both ammonium persulfate and sodium hydrogen sulfite.
- a water-soluble azo type polymerization initiator such as 2,2'-azobis(2-amidinopropane) hydrochloride
- a water-soluble redox type polymerization initiator such as both ammonium persulfate and sodium hydrogen sulfite.
- Temperature of the polymerization system can be selected arbitrarily depending on the property of the polymerization initiator used within the range of 0 to 100°C.
- a chain transfer agent such as isopropylalcohol or mercaptan can be added and used by arbitrary selection in the same manner as ordinary radical polymerization.
- stirring at a peripheral speed of a stirrer of at least 1 meter/min must be performed for smoothening the precipitation of fine polymer particles. There is no upper limit of the stirring speed and any stirring conditions can be selected provided that the contents do not overflow from the equipment.
- preparation of the dispersibility retaining agent is generally performed by the stationary polymerization in an aqueous solution
- the polymerization therefor in the present invention is preferably performed under stirring from the viewpoint of the homogenization of products.
- the polymer concentration in the dispersion of the present invention is high or at least 5 wt% and is normally from 5 wt% to about 40 wt%.
- the dispersion of the present invention contains a high concentration of formed polymer, the viscosity of the dispersion is low, normally low at 30 to 5000 mPa ⁇ s, and preferably 30 to 1500 mPa ⁇ s, because the polymer is stably dispersed in a dispersion medium in a state of fine particles. Therefore, as its characteristics, the polymer dispersion can flow easily and can be handled very easily.
- the polymer particles in the dispersion of the present invention can be recognized in a non-diluted state and in a state diluted 10 times with distilled water when it is magnified by a factor of 400 with an optical microscope.
- the average particle diameter of the polymer particles is normally 1 to 100 ⁇ m, preferably 2 to 50 ⁇ m, and more preferably 2 to 30 ⁇ m.
- the average particle diameter of the polymer particles exceeds 100 ⁇ m, since the particles tend to precipitate easily, settling stability deteriorates.
- solubility also deteriorates at the time of use due to the large size of the polymer particles even when mixed with water, thus requiring a long time to completely dissolve the polymer.
- the dispersion of the present invention has excellent settling stability and any trouble such as adherence of particles to each other thereby creating masses does not occur even during storage at the normal temperature.
- the solubility thereof in water during use is extremely good.
- the molecular weight of the polymer in the dispersion of the present invention is not specially limited. If the dispersion of the present invention is expressed by the solution viscosity when dissolved in 2 wt% of aqueous salt solution of ammonium sulfate (viscosity measured at 25°C by using a Brookfield viscometer) in such a manner that the concentration of the polymer becomes 0.5 wt%, it is normally in the range of 5 to 200 mPa ⁇ s. Also, the dispersion of the present invention hardly has any change in viscosity with time even after storage for 1 month.
- the polymer particles can be recognized with a microscope and when an alkali is added to the dispersion to adjust the pH of the dispersion to 7.0, said polymer particles are dissolved to form an aqueous solution. That is, the dispersion of the present invention can be said to be a dispersion of the fine particles of water-insoluble polymer.
- paper strengthening effects are obtained by coating or impregnating an aqueous diluted dispersion of said paper strengthening agent onto a dry paper or wet paper surface and then drying.
- the paper strengthening agent can be used in combination with another wet end chemical, for example a retention aid for fillers or a drainage aid. More specifically, an aqueous solution of cationic starch, cationic polyacrylamide or other wet end paper strengthening agent and so forth is added and mixed with a paper material, and spraying a diluted aqueous dispersion of the paper strengthening agent according to the present invention onto wet paper at each intermediate stage of formation of the sheet, namely before the suction part or on the suction part, with a wire to impregnate said diluted aqueous dispersion into the paper.
- another wet end chemical for example a retention aid for fillers or a drainage aid.
- polymer is impregnated onto the surface and inside the paper by coating a diluted aqueous dispersion of the paper strengthening agent of the present invention onto the resulting dry paper by a size press, gate roll coater or blade coater and so forth.
- Paper to which the paper strengthening agent is added for these non-wet ends is frequently used in printing paper, recording paper and PPC paper (i.e. paper for plan paper copy), and the sheets are typically single layer.
- a plurality of webs are typically combined with each other.
- the strength of the paper such as the interlayer adhesive paper strength of a plurality of laminated sheets of paper, can be increased making it possible to prevent interlayer separation.
- interlayer separation preventive agents such as starch, modified starch, casein and galactomannan may be also be used in the paper strengthening agent of the present invention.
- the present invention is characterized in that the polymer comprising a water-soluble monomer containing (meth)acrylate is not used.
- Methodacrylic (co)polymer is refractory and has a low viscosity even though the molecular weight is high, enabling even highly concentrated diluted aqueous dispersions to be coated onto a surface easily.
- a high molecular weight polymer can be efficiently coated in a water-insoluble state. Since the pH rises when the coated polymer is impregnated into paper, a portion of the polymer becomes water-soluble and transforms into a paste-like substance. Consequently, it is expected to function as an adhesive.
- the polymer dispersion is sprayed or coated onto the surface after diluting to a polymer concentration of 0.1 to 0.5 wt%.
- the amount of polymer added to the paper by spraying or coating is a polymer net amount of 0.05 to 1.0 wt% per pulp SS (i.e. suspended solid), and preferably 0.1 to 0.5 wt%.
- Example-1 In a reactor equipped with a stirrer, a nitrogen aeration pipe and a temperature controller, 10 parts of a monomer composition consisting of 15 mol% of acrylic acid, 55 mol% of acrylamide and 30 mol% of acrylonitrile, and 1 part of polydimethyldiallylammonium chloride as a dispersant (manufactured by CPS Co., trade name: Age Flock WT40HV) were dissolved in 89 parts of deionized water. Thereafter, as a polymerization initiator, 2,2'-azobis[2-(imidazoline-2-yl)propane] dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-044) was added. Under stirring, the polymerization was carried out for 20 hours at 35°C to obtain a polymer dispersion (pH 3) in which 5 to 50 ⁇ m fine particles were dispersed. This dispersion is referred to as "Sample-1".
- the viscosity of said polymer dispersion (Sample-1) was 1000 mPa ⁇ s, fine particles were recognized with a microscope even after diluting 10 times with distilled water, and the polymer was essentially confirmed to be water-insoluble.
- Sodium carbonate aqueous solution was mixed in said dispersion to adjust the pH of the dispersion to 7, after which the polymer was dissolved and the molecular weight thereof was determined from the intrinsic viscosity based on said aqueous solution.
- Example-2 The same operation as that of Preparative Example-1 was performed with the exception of using a monomer composition consisting of 30 mol% of acrylic acid, 45 mol% of acrylamide and 25 mol% of acrylonitrile to obtain a water-insoluble polymer dispersion. This dispersion is referred to as "Sample-2".
- the viscosity of said polymer dispersion (Sample-3) was 500 mPa ⁇ s or less, fine particles were recognized with a microscope even after diluting said dispersion 10 times with distilled water, and the polymer was essentially confirmed to be water-insoluble.
- Sodium carbonate aqueous solution was mixed in said dispersion to adjust the pH of the dispersion to 7, after which the polymer was dissolved and the molecular weight thereof was determined from the intrinsic viscosity based on said aqueous solution.
- Example-4 a polymer dispersion in which 10 to 20 ⁇ m fine particles were dispersed in the aqueous salt solution. This dispersion is referred to as "Sample-4".
- the viscosity of said polymer dispersion (Sample-4) was 500 mPa ⁇ s or less, fine particles were recognized in said dispersion with a microscope even after diluting 10 times with distilled water, and the polymer was essentially confirmed to be water-insoluble.
- Sodium carbonate aqueous solution was mixed in said dispersion to adjust the pH of the dispersion to 7, after which the polymer was dissolved and the molecular weight thereof was determined from the intrinsic viscosity based on said aqueous solution.
- the polymer dispersion of the present example was diluted with pH 3.0 acidic water to prepare a diluted aqueous dispersion having a polymer concentration of 2.0%.
- This diluted dispersion was coated onto commercially available medium quality paper (basis weight: 55 g/m 2 , manufactured by Daishowa Paper Co., Ltd., neutral paper) using a coating rod and roll dried for 5 minutes at 105°C to obtain coated paper.
- the amounts of coated polymer were 0.1 g/m 2 and 0.2 g/m 2 .
- the results of bursting strength and surface strength tests are shown in Table 2. Results of Paper Strengthening Effect Test No.
- the polymer dispersion of the present example was diluted with pH 3.0 acidic water followed by the addition of acidic starch to prepare a coating liquid having a polymer concentration of 2.0% and acidic starch concentration of 2.0%.
- This coating liquid was coated onto medium quality paper having a basis weight of 60 g/m 2 using a gate roll coater followed by drying to obtain a coated paper.
- the amounts of coated polymer were 0.1 g/m 2 and 0.2 g/m 2 .
- the results of bursting strength and surface strength tests are shown in Table 3. Results of Paper Strengthening Effect Test No.
- the paper surface coating liquids prepared from the paper strengthening agents of the present invention can be easily coated onto paper in the form of a diluted dispersion having low viscosity and good workability, and are able to provide paper having high paper strength.
- Old corrugated cardboard was beaten in a Niagara type beater and adjusted to the freeness of 400 ml of Canadian Standard Freeness (C.S.F.) to prepare pulp.
- a liquid bond of 2% was added to said pulp followed by stirring to obtain a uniform mixture.
- the resulting pulp slurry was diluted to 0.5%, and wet paper A was obtained having a dry basis weight of 125 g/m 2 and moisture content of 96% using a hand-made paper tester.
- Diluted dispersions of each sample having a polymer concentration of 0.25% were sprayed onto one side of wet paper A using a nozzle at a pressure of 2 atm according to the polymer amounts described in Table 4 (polymer content per solid content of the pulp), followed by suctioning from the opposite side thereof.
- This a model test in the case of spraying at a wire part for forming paper from pulp slurry.
- wet paper A was placed between blankets and pressed twice with a test calendar followed by drying to obtain paper for measuring paper
- the paper strengthening agent of the present invention was able to be sprayed easily in the form of a diluted dispersion with low viscosity and good workability, and paper was able to be provided having good establishment of retention in the paper and high paper strength without the nozzle becoming clogged or the occurrence of non-uniform adhesion.
- Old corrugated cardboard was beaten in a Niagara type beater and adjusted to the freeness of 400 ml of the Canadian Standard Freeness (C.S.F.) to prepare pulp.
- a liquid bond of 2% and a commercially available anionic paper strengthening agent of 0.9% were added to the pulp and stirred to mix uniformly.
- the resulting pulp slurry was diluted to 0.5%, and wet paper A having a dry basis weight of 100 g/m 2 and moisture content of 86% and wet paper B having a dry basis weight of 100 g/m 2 and moisture content of 96% were prepared by a hand-made paper tester.
- Diluted dispersions of each sample of the present invention having a polymer concentration of 0.5% were sprayed onto one side of wet paper A using a nozzle at a pressure of 2 atm according to the polymer amounts described in Table 5 (polymer content per solid content of the pulp). Thereafter, the coated surface of the wet paper A was overlaid with the surface of wet paper B after which they were placed between blankets and pressed through a test calendar and dried to obtain a dried combination board. After adjusting the moisture of this combination board, the T-peel strength thereof (g/inch) was measured in accordance with J-TAPPI paper pulp test method No. 19-77. The results are shown in Table 5.
- the interlayer adhesive paper strengthening agent of the present invention can be easily sprayed in the form of a diluted dispersion having low viscosity and good workability, and combination paper is able to be provided having high interlayer separation effects without the nozzle becoming clogged or the occurrence of non-uniform adhesion.
Landscapes
- Paper (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Description
- The present invention relates to a paper strengthening agent comprising a dispersion of fine water-insoluble polymer particles manufactured by polymerizing a monomer containing (meth)acrylic acid in an aqueous solution and precipitating the produced polymer, which is added to a paper layer after a paper layer is formed in a paper making process and relates to a paper strengthening method wherein a low-viscosity polymer dispersion prepared by diluting the present paper strengthening agent with water is impregnated into paper by spraying or coating.
- The Laid-Open Japanese Patent Application No. Sho 62-20511 discloses a method of obtaining a water-soluble polymer dispersion by polymerizing a monomer in an aqueous salt solution that dissolves the monomer and does not dissolve a formed polymer in the presence of a polymer electrolyte.
- On the other hand, the Laid-open Japanese Patent Application No. Sho 60-185900 discloses a method for obtaining a dispersion of fine polymer particles by polymerizing acrylic acid with acrylamide in an aqueous salt solution that dissolves the monomers but does not dissolve the formed polymer. In this method, the fine particles can be obtained in the absence of any polymer electrolyte. The fine polymer particles obtained here are water-insoluble and dissolved in a solvent if the dispersion is neutralized. That is, it is a different technique from that proposed in the Laid-open Japanese Patent Application No. Sho 62-20511. However, the fine particles in the dispersion of acrylic acid-acrylamide copolymer agglomerate on standing resulting in curding in the manner of bean curd, thereby having the disadvantage of being unable to be stored for long periods of time.
- An object of the present invention is to increase bursting strength, ring crush strength and surface paper strength such as wax pic by efficiently impregnating a paper layer with a high molecular weight polymer.
- Another object of the present invention is to increase the interlayer adhesive paper strength by adhering a high molecular weight polymer to a plurality of web surfaces.
- The inventors of the present invention discovered that a dispersion of fine polymer particles having a low viscosity, good workability and excellent stability for preservation can be manufactured by polymerizing a monomer containing (meth)acrylic acid in the presence of a dispersibility retaining agent such as a cationic polymer electrolyte to precipitate the produced polymer. Moreover, during the course of various attempts to search for applications for this dispersion, the inventors of the present invention also discovered that said dispersion demonstrates outstanding effects such as paper strengthening by coating said dispersion onto dry paper with a size press, gate roll coater or blade coater and so forth, paper strengthening by spray impregnating said dispersion into wet paper on a wire part, and interlayer adhesion paper strengthening by adhering a polymer of said dispersion onto a plurality of web surfaces, thereby leading to completion of the present invention.
- A first aspect of the present invention is to provide a paper strengthening agent substantially comprising a polymer dispersion manufactured by polymerizing a monomer containing (meth)acrylic acid in an aqueous solution and precipitating the produced polymer as fine particles, and which is added to a paper layer after a paper layer is formed, wherein
- (1) the concentration of the (meth)acrylic acid (co)polymer in the polymer dispersion is at least 5 wt%,
- (2) the average particle diameter of the (meth)acrylic acid (co)polymer particles in the polymer dispersion is 1 to 100 µm,
- (3) the viscosity of the polymer dispersion is 30 to 5000 mPa·s immediately after and one month after the production,
- (4) the polymer particles can be recognized when the polymer dispersion is diluted 10 times with distilled water and the diluted dispersion is magnified by a factor of 400 and observed with a microscope, and
- (5) when the pH of the diluted dispersion is adjusted to 7.0 by adding an alkali, the polymer particles are dissolved to form an aqueous solution.
-
- A second aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the polymer dispersion is polymerized and precipitated in the presence of a dispersibility retaining agent comprising a polyvalent electrolyte.
- A third aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is one selected from a cationic polymer electrolyte, a surface active agent having a polyvalent cationic hydrophilic group and a hydrophobic group, and a mixture thereof.
- A fourth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the weight ratio of the monomer containing (meth)acrylic acid in an aqueous solution to the dispersibility retaining agent is 100:1 to 10:1.
- A fifth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the viscosity of said polymer dispersion is 30 to 1500 mPa·s immediately after and one month after the production.
- A sixth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is dimethyldiallylammonium chloride (co)polymer.
- A seventh aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is an alkyl group-substituted and/or an aralkyl group-substituted polyethylenepolyamine.
- An eighth aspect of the present invention is to provide a paper strengthening agent characterized in that, in the above-mentioned paper strengthening agent, the dispersibility retaining agent is an alkyl group having at least 5 carbon atoms-substituted and/or an aralkyl group-substituted pentaethylenehexamine.
- A ninth aspect of the present invention is to provide a paper strengthening method comprising the steps of: diluting the above-mentioned paper strengthening agent with water to prepare a diluted dispersion, coating or impregnating said diluted dispersion onto a dry paper, and drying the treated dry paper.
- A tenth aspect of the present invention is to provide a paper strengthening method wherein a diluted dispersion of the above-mentioned paper strengthening agent is impregnated into wet paper.
- An eleventh aspect of the present invention is to provide a paper strengthening method wherein a diluted dispersion of the above-mentioned paper strengthening agent is spray impregnated into wet paper.
- A twelfth aspect of the present invention is to provide a paper strengthening method wherein the wet paper in the above method is of a single layer.
- A thirteenth aspect of the present invention is to provide a method of preventing interlayer separation comprising the steps of spraying a diluted dispersion of the above-mentioned paper strengthening agent onto a web surface to prepare a plurality of webs having a polymer adhered to surfaces thereof, and pressing the surfaces of said webs so as to be superimposed followed by drying.
- The monomer that contains (meth)acrylic acid used in the present invention is a mixture of 5 to 50 mol% of acrylic acid, methacrylic acid or a mixture thereof, and itaconic acid and/or acryloylaminoisobutyl sulfonic acid and so forth over a range that does not lower the degree of polymerization or have a detrimental effect on solubility; and, 50 to 95 mol% of one type of nonionic monomer selected from the group consisting of (meth)acrylamide, (meth)acrylonitrile, N-vinylcarboxylic amide, N-isopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, methyl(meth)acrylate, hydroxyethyl(meth)acrylate, vinylmethylether, vinylacetate, styrene and a mixture thereof.
- Cationic monomer can be polymerized as a component of the monomer containing (meth)acrylic acid over the range in which water insolubility of the resulted polymer can be secured when diluting with distilled water.
- Among them, a monomer composition that contains 5 to 50 mol% of (meth)acrylic acid, 50 to 95 mol% of (meth)acrylamide and 0 to 50 mol% of (meth)acrylonitrile is most preferable.
- It is preferable to carry out polymerization in the presence of a dispersibility retaining agent in order to obtain a polymer dispersion in the present invention. Examples of the dispersibility retaining agent comprising a cationic polymer electrolyte used in the present invention are (co)polymers of salts or quaternary products of dialkylaminoalkyl(meth)acrylate, (co)polymers of salts or quaternary products of dialkylaminoalkyl(meth)acrylamide, and (co)polymers of dialkyldiallylammonium salt.
- Examples of the salts or quaternary products of dialkylaminoalkyl(meth)acrylate include dimethylaminoethyl(meth)acrylate hydrochloride and acryloyloxyethyltrimethylammonium chloride. Also, examples of the salts or quaternary products of the dialkylaminoalkyl(meth)acrylamide include hydrochlorides or methylated products of dialkylaminopropyl(meth)acrylamide. An example of dialkyldiallylammonium salt is dimethyldiallylammonium chloride.
- Not only one type, but also a mixture of two or more types of cationic monomers that form said cationic water-soluble polymer can be used.
- The cationic water-soluble polymer may be a homopolymer or a copolymer with a nonionic monomer such as acrylamide.
- A particularly preferable cationic water-soluble polymer is dimethyldiallylammonium chloride (co)polymer.
- An example of a dispersibility retaining agent comprising a surface active agent having a polyvalent cationic hydrophilic group and a hydrophobic group used in the present invention is a substituted polyethylenepolyamine in which at least one hydrogen atom at a nitrogen atom thereof is substituted by an alkyl group and/or an aralkyl group. An alkyl group-substituted product of pentaethylenehexamine having at least 5 carbon atoms in said alkyl group is effective.
- The weight ratio of the monomer that contains (meth)acrylic acid to the dispersibility retaining agent is preferably 100:1 to 10:1. If the amount of the dispersibility retaining agent is too small, the dispersion curds into the form of bean curd. On the other hand, excessive addition of dispersibility retaining agent is economically meaningless.
- The dispersibility retaining agent according to present invention may be a sole compound or a mixture thereof.
- As a result of adding dispersibility retaining agent within said range, the viscosity of the polymer dispersion is maintained within the range of 30 to 5000 mPa·s immediately after and one month after the production, and is stable for a long time.
- A product having a viscosity of 30 to 1500 mPa·s is preferable in terms of handling when considering convenience during use.
- Since the polymer dispersion of the present invention uses a polyvalent cationic compound as the dispersibility retaining agent, the surface charge of the polymer particles is considered to be cationic, and it can also be mixed with an aqueous solution of a water-soluble cationic polymer and an aqueous dispersion.
- An aqueous salt solution may also be used in the present invention for the purpose of promoting polymer precipitation. Examples of the salt that forms said aqueous salt solution include alkaline metal salts such as sodium salt and potassium salt, and ammonium salts such as ammonium chloride, ammonium sulfate and ammonium nitrate. The concentration and pH of said aqueous salt solution must be such that the monomers containing (meth)acrylic acid dissolve, while the polymer that is formed does not. In contrast, it is necessary that the dispersibility retaining agent that is also present be soluble in said aqueous salt solution.
- The (meth)acrylic acid (co)polymer dispersion and the dispersibility retaining agent in the present invention can respectively be obtained by dissolving monomer(s) in an aqueous medium under nitrogen atmosphere without oxygen, and radical polymerizing the monomer(s) by adding a water-soluble azo type polymerization initiator such as 2,2'-azobis(2-amidinopropane) hydrochloride or a water-soluble redox type polymerization initiator using such as both ammonium persulfate and sodium hydrogen sulfite.
- Temperature of the polymerization system can be selected arbitrarily depending on the property of the polymerization initiator used within the range of 0 to 100°C. For adjusting the molecular weight of the polymer obtained, a chain transfer agent such as isopropylalcohol or mercaptan can be added and used by arbitrary selection in the same manner as ordinary radical polymerization. At the time of preparing the (meth)acrylic acid (co)polymer dispersion, stirring at a peripheral speed of a stirrer of at least 1 meter/min must be performed for smoothening the precipitation of fine polymer particles. There is no upper limit of the stirring speed and any stirring conditions can be selected provided that the contents do not overflow from the equipment. Although preparation of the dispersibility retaining agent is generally performed by the stationary polymerization in an aqueous solution, the polymerization therefor in the present invention is preferably performed under stirring from the viewpoint of the homogenization of products.
- The polymer concentration in the dispersion of the present invention is high or at least 5 wt% and is normally from 5 wt% to about 40 wt%.
- Although the dispersion of the present invention contains a high concentration of formed polymer, the viscosity of the dispersion is low, normally low at 30 to 5000 mPa·s, and preferably 30 to 1500 mPa·s, because the polymer is stably dispersed in a dispersion medium in a state of fine particles. Therefore, as its characteristics, the polymer dispersion can flow easily and can be handled very easily.
- The polymer particles in the dispersion of the present invention can be recognized in a non-diluted state and in a state diluted 10 times with distilled water when it is magnified by a factor of 400 with an optical microscope. At this time, the average particle diameter of the polymer particles is normally 1 to 100 µm, preferably 2 to 50 µm, and more preferably 2 to 30 µm. When the average particle diameter of the polymer particles exceeds 100 µm, since the particles tend to precipitate easily, settling stability deteriorates. Moreover, solubility also deteriorates at the time of use due to the large size of the polymer particles even when mixed with water, thus requiring a long time to completely dissolve the polymer. On the contrary, the dispersion of the present invention has excellent settling stability and any trouble such as adherence of particles to each other thereby creating masses does not occur even during storage at the normal temperature. In addition, the solubility thereof in water during use is extremely good.
- The molecular weight of the polymer in the dispersion of the present invention is not specially limited. If the dispersion of the present invention is expressed by the solution viscosity when dissolved in 2 wt% of aqueous salt solution of ammonium sulfate (viscosity measured at 25°C by using a Brookfield viscometer) in such a manner that the concentration of the polymer becomes 0.5 wt%, it is normally in the range of 5 to 200 mPa·s. Also, the dispersion of the present invention hardly has any change in viscosity with time even after storage for 1 month.
- When the dispersion of the present invention is diluted 10 times, the polymer particles can be recognized with a microscope and when an alkali is added to the dispersion to adjust the pH of the dispersion to 7.0, said polymer particles are dissolved to form an aqueous solution. That is, the dispersion of the present invention can be said to be a dispersion of the fine particles of water-insoluble polymer.
- In the present invention, paper strengthening effects are obtained by coating or impregnating an aqueous diluted dispersion of said paper strengthening agent onto a dry paper or wet paper surface and then drying.
- In the paper strengthening method of the present invention, the paper strengthening agent can be used in combination with another wet end chemical, for example a retention aid for fillers or a drainage aid. More specifically, an aqueous solution of cationic starch, cationic polyacrylamide or other wet end paper strengthening agent and so forth is added and mixed with a paper material, and spraying a diluted aqueous dispersion of the paper strengthening agent according to the present invention onto wet paper at each intermediate stage of formation of the sheet, namely before the suction part or on the suction part, with a wire to impregnate said diluted aqueous dispersion into the paper.
- In another embodiment according to the present invention, after drying manufactured paper, polymer is impregnated onto the surface and inside the paper by coating a diluted aqueous dispersion of the paper strengthening agent of the present invention onto the resulting dry paper by a size press, gate roll coater or blade coater and so forth.
- Nearly the entire amount of polymer coated according to said method is retained within the paper, namely within the pulp sheet. Due to adhesion of pulp fibers and so forth, it is possible to increase not only surface paper strength, but also bursting strength and ring crush strength.
- Paper to which the paper strengthening agent is added for these non-wet ends is frequently used in printing paper, recording paper and PPC paper (i.e. paper for plan paper copy), and the sheets are typically single layer.
- In contrast, in the production of cardboard, a plurality of webs are typically combined with each other. By spraying a diluted aqueous dispersion of the paper strengthening agent of the present invention onto a web surface to prepare a plurality of webs adhered with polymer on the surface, and drying after pressing so as to overlap the surfaces of said webs, the strength of the paper, such as the interlayer adhesive paper strength of a plurality of laminated sheets of paper, can be increased making it possible to prevent interlayer separation.
- Furthermore, conventional interlayer separation preventive agents such as starch, modified starch, casein and galactomannan may be also be used in the paper strengthening agent of the present invention.
- The present invention is characterized in that the polymer comprising a water-soluble monomer containing (meth)acrylate is not used.
- (Meth)acrylic (co)polymer is refractory and has a low viscosity even though the molecular weight is high, enabling even highly concentrated diluted aqueous dispersions to be coated onto a surface easily.
- According to the present invention, a high molecular weight polymer can be efficiently coated in a water-insoluble state. Since the pH rises when the coated polymer is impregnated into paper, a portion of the polymer becomes water-soluble and transforms into a paste-like substance. Consequently, it is expected to function as an adhesive.
- When considering the properties as a coating agent, there is no occurrence of decay in comparison with starch, and there are no increases in viscosity in comparison with an aqueous solution of (meth)acrylate (co)polymer. Thus, there is no difficulty in spray coating onto wet paper and there is no occurrence of uneven coating of dry paper surfaces.
- In the method of the present invention, the polymer dispersion is sprayed or coated onto the surface after diluting to a polymer concentration of 0.1 to 0.5 wt%.
- The amount of polymer added to the paper by spraying or coating is a polymer net amount of 0.05 to 1.0 wt% per pulp SS (i.e. suspended solid), and preferably 0.1 to 0.5 wt%.
- Although the following provides a detailed explanation of the present invention through its examples, the present invention is not limited to the following.
- In a reactor equipped with a stirrer, a nitrogen aeration pipe and a temperature controller, 10 parts of a monomer composition consisting of 15 mol% of acrylic acid, 55 mol% of acrylamide and 30 mol% of acrylonitrile, and 1 part of polydimethyldiallylammonium chloride as a dispersant (manufactured by CPS Co., trade name: Age Flock WT40HV) were dissolved in 89 parts of deionized water. Thereafter, as a polymerization initiator, 2,2'-azobis[2-(imidazoline-2-yl)propane] dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name: VA-044) was added. Under stirring, the polymerization was carried out for 20 hours at 35°C to obtain a polymer dispersion (pH 3) in which 5 to 50 µm fine particles were dispersed. This dispersion is referred to as "Sample-1".
- The viscosity of said polymer dispersion (Sample-1) was 1000 mPa·s, fine particles were recognized with a microscope even after diluting 10 times with distilled water, and the polymer was essentially confirmed to be water-insoluble. Sodium carbonate aqueous solution was mixed in said dispersion to adjust the pH of the dispersion to 7, after which the polymer was dissolved and the molecular weight thereof was determined from the intrinsic viscosity based on said aqueous solution.
- The same operation as that of Preparative Example-1 was performed with the exception of using a monomer composition consisting of 30 mol% of acrylic acid, 45 mol% of acrylamide and 25 mol% of acrylonitrile to obtain a water-insoluble polymer dispersion. This dispersion is referred to as "Sample-2".
- In a reactor equipped with a stirrer, a nitrogen aeration pipe and a temperature controller, 20 parts of a monomer composition consisting of 30 mol% of acrylic acid, 60 mol% of acrylamide and 10 mol% of acrylonitrile, and 1 part of polydimethyldiallylammonium chloride as a dispersant (manufactured by CPS Co., trade name: Age Flock WT40HV) were dissolved in 79 parts of an aqueous solution of sodium chloride having a concentration of 20 wt%. Thereafter, as a polymerization initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-50) was added. Under stirring, the polymerization was carried out for 10 hours at 53°C to obtain a polymer dispersion (pH 3) in which 10 to 20 µm fine particles were dispersed in the aqueous salt solution. This dispersion is referred to as "Sample-3".
- The viscosity of said polymer dispersion (Sample-3) was 500 mPa·s or less, fine particles were recognized with a microscope even after diluting said dispersion 10 times with distilled water, and the polymer was essentially confirmed to be water-insoluble. Sodium carbonate aqueous solution was mixed in said dispersion to adjust the pH of the dispersion to 7, after which the polymer was dissolved and the molecular weight thereof was determined from the intrinsic viscosity based on said aqueous solution.
- In a reactor equipped with a stirrer, a nitrogen aeration pipe and a temperature controller, 20 parts of a monomer composition consisting of 10 mol% of acrylic acid, 70 mol% of acrylamide and 20 mol% of acrylonitrile, and 1 part of a compound in which 3 moles of benzyl chloride were added to pentaethylenehexamine as a dispersant were dissolved in 79 parts of an aqueous solution of sodium chloride having a concentration of 20 wt%. Thereafter, as a polymerization initiator, 2,2'-azobis(2-amidinopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-50) was added. Under stirring, the polymerization was carried out for 10 hours at 53°C to obtain a polymer dispersion (pH 3) in which 10 to 20 µm fine particles were dispersed in the aqueous salt solution. This dispersion is referred to as "Sample-4".
- The viscosity of said polymer dispersion (Sample-4) was 500 mPa·s or less, fine particles were recognized in said dispersion with a microscope even after diluting 10 times with distilled water, and the polymer was essentially confirmed to be water-insoluble.
- Sodium carbonate aqueous solution was mixed in said dispersion to adjust the pH of the dispersion to 7, after which the polymer was dissolved and the molecular weight thereof was determined from the intrinsic viscosity based on said aqueous solution.
- Polymer characteristics of the Sample-1 to Sample-4 are shown in Table 1.
No. Sample Name Monomers (mol%) Molecular weight AAc AAm AN 1 Sample-1 15 55 30 2,000,000 2 Sample-2 30 45 25 3,000,000 3 Sample-3 30 60 10 2,500,000 4 Sample-4 10 70 20 3,700,000 AAc: Acrylic acid
AAm: Acrylamide
AN: Acrylonitrile - The polymer dispersion of the present example was diluted with pH 3.0 acidic water to prepare a diluted aqueous dispersion having a polymer concentration of 2.0%. This diluted dispersion was coated onto commercially available medium quality paper (basis weight: 55 g/m2, manufactured by Daishowa Paper Co., Ltd., neutral paper) using a coating rod and roll dried for 5 minutes at 105°C to obtain coated paper. The amounts of coated polymer were 0.1 g/m2 and 0.2 g/m2. The results of bursting strength and surface strength tests are shown in Table 2.
Results of Paper Strengthening Effect Test No. Sample Name Coated Amount (g/m2) Burst Factor Surface Strength WAX PIC 1 Sample-1 0.1 2.15 12A 2 Sample-1 0.2 2.24 13A 3 Sample-2 0.1 2.13 12A 4 Sample-3 0.1 2.12 12A 5 Sample-4 0.1 2.12 12A 6 Acidic starch only 0.5 1.50 11A 7 Non-coated 0 1.30 8A WAX PIC: measured according to TAPPI (Technology Association of Pulp and Paper Industries) T459os-75
BURSTING STRENGTH TEST: TAPPI T403om-85 - The polymer dispersion of the present example was diluted with pH 3.0 acidic water followed by the addition of acidic starch to prepare a coating liquid having a polymer concentration of 2.0% and acidic starch concentration of 2.0%. This coating liquid was coated onto medium quality paper having a basis weight of 60 g/m2 using a gate roll coater followed by drying to obtain a coated paper. The amounts of coated polymer were 0.1 g/m2 and 0.2 g/m2. The results of bursting strength and surface strength tests are shown in Table 3.
Results of Paper Strengthening Effect Test No. Sample Name Coated Amount (g/m2) Burst Factor Surface Strength WAX PIC 1 Sample-1 0.1 2.15 12A 2 Sample-1 0.2 2.24 13A 3 Sample-2 0.1 2.14 12A 4 Sample-2 0.2 2.24 13A 5 Acidic starch only 0.6 1.50 11A 6 Non-coated 0.6 1.50 11A - The paper surface coating liquids prepared from the paper strengthening agents of the present invention can be easily coated onto paper in the form of a diluted dispersion having low viscosity and good workability, and are able to provide paper having high paper strength.
- Old corrugated cardboard was beaten in a Niagara type beater and adjusted to the freeness of 400 ml of Canadian Standard Freeness (C.S.F.) to prepare pulp. A liquid bond of 2% was added to said pulp followed by stirring to obtain a uniform mixture. The resulting pulp slurry was diluted to 0.5%, and wet paper A was obtained having a dry basis weight of 125 g/m2 and moisture content of 96% using a hand-made paper tester. Diluted dispersions of each sample having a polymer concentration of 0.25% were sprayed onto one side of wet paper A using a nozzle at a pressure of 2 atm according to the polymer amounts described in Table 4 (polymer content per solid content of the pulp), followed by suctioning from the opposite side thereof. This a model test in the case of spraying at a wire part for forming paper from pulp slurry. Next, wet paper A was placed between blankets and pressed twice with a test calendar followed by drying to obtain paper for measuring paper strength.
- After adjusting the moisture of the resulting paper for measuring paper strength, bursting strength and ring crush strength were measured, the results of which are shown in Table 4.
Results of Paper Strengthening Effect Test No. Sample Name Amt. Added (%) Burst Factor Ring Crush Strength 1 Sample-1 0.3 2.15 15.02 2 Sample-2 0.3 2.14 15.01 3 Sample-3 0.3 2.14 15.00 4 Sample-4 0.3 2.14 15.01 5 Control-A 0.3 1.89 14.12 6 Control-B 0.3 1.90 14.12 7 Blank 0 1.50 11.73 REMARKS: Control-A is a commercially available mannic paper strengthening agent for wet ends (manufactured by Arakawa Chemical Industries, Ltd., trade name: Polystron 609), while Control-B is a commercially available Hoffman reaction type paper strengthening agent for wet ends (manufactured by Seiko Chemical Industries, Ltd., trade name: Stargum FN).
RING CRUSH TEST: TAPPI T472wd-76 - The paper strengthening agent of the present invention was able to be sprayed easily in the form of a diluted dispersion with low viscosity and good workability, and paper was able to be provided having good establishment of retention in the paper and high paper strength without the nozzle becoming clogged or the occurrence of non-uniform adhesion.
- Old corrugated cardboard was beaten in a Niagara type beater and adjusted to the freeness of 400 ml of the Canadian Standard Freeness (C.S.F.) to prepare pulp. A liquid bond of 2% and a commercially available anionic paper strengthening agent of 0.9% were added to the pulp and stirred to mix uniformly. The resulting pulp slurry was diluted to 0.5%, and wet paper A having a dry basis weight of 100 g/m2 and moisture content of 86% and wet paper B having a dry basis weight of 100 g/m2 and moisture content of 96% were prepared by a hand-made paper tester. Diluted dispersions of each sample of the present invention having a polymer concentration of 0.5% were sprayed onto one side of wet paper A using a nozzle at a pressure of 2 atm according to the polymer amounts described in Table 5 (polymer content per solid content of the pulp). Thereafter, the coated surface of the wet paper A was overlaid with the surface of wet paper B after which they were placed between blankets and pressed through a test calendar and dried to obtain a dried combination board. After adjusting the moisture of this combination board, the T-peel strength thereof (g/inch) was measured in accordance with J-TAPPI paper pulp test method No. 19-77. The results are shown in Table 5.
- With the exception of using aqueous polymer solutions by adjusting the diluted dispersions of each sample of the present invention having a polymer concentration of 0.5% used in the examples to pH 7.0 with sodium hydroxide to dissolve the polymer, the same procedure was used as that in the examples. The results are shown in Table 5.
Results of Interlayer Adhesion Effect Test Sample Name Diluted Dispersion pH Polymer Added Amount T-Peel Strength (g/inch) Spray Form Example 1 Sample-1 2.7 0.3% 402 Mist Example 2 Sample-2 2.7 0.3% 400 Mist Comp. Ex. 1 Sample-1 7.0 0.3% 125 Large drops Comp. Ex. 2 Sample-2 7.0 0.3% 136 Large drops Comp. Ex. 3 Sample-3 7.0 0.3% 126 Large drops Comp. Ex. 4 Sample-4 7.0 0.3% 134 Large drops - The interlayer adhesive paper strengthening agent of the present invention can be easily sprayed in the form of a diluted dispersion having low viscosity and good workability, and combination paper is able to be provided having high interlayer separation effects without the nozzle becoming clogged or the occurrence of non-uniform adhesion.
- While the presently preferred embodiments of the present invention have been shown and described, it will be understood that the present invention is not limited thereto, and that various changes and modifications may be made by those skilled in the art without departing from the scope of the invention as set forth in the appended claims.
Claims (13)
- A paper strengthening agent comprising a polymer dispersion manufactured by polymerizing a monomer containing (meth)acrylic acid in an aqueous solution and precipitating the produced polymer as fine particles, and which is added to a paper layer after a paper layer is formed, wherein(1) the concentration of the (meth)acrylic acid (co)polymer in said polymer dispersion is at least 5 wt%,(2) the average particle diameter of the (meth)acrylic acid (co)polymer particles in said polymer dispersion is 1 to 100 µm,(3) the viscosity of said polymer dispersion is 30 to 5000 mPa·s immediately after and one month after the production,(4) the polymer particles can be recognized when said polymer dispersion is diluted 10 times with distilled water and the diluted dispersion is magnified by a factor of 400 and observed with a microscope, and(5) when the pH of said diluted dispersion is adjusted to 7.0 by adding an alkali, said polymer particles are dissolved to form an aqueous solution.
- The paper strengthening agent according to claim 1, wherein said polymer dispersion is polymerized and precipitated in the presence of a dispersibility retaining agent comprising a polyvalent electrolyte.
- The paper strengthening agent according to claim 1 or claim 2, wherein said dispersibility retaining agent is one selected from a cationic polymer electrolyte, a surface active agent having a polyvalent cationic hydrophilic group and hydrophobic group, and a mixture thereof.
- The paper strengthening agent according to any one of claims 1 to 3, wherein the weight ratio of the monomer containing (meth)acrylic acid in an aqueous solution to the dispersibility retaining agent is 100:1 to 10:1.
- The paper strengthening agent according to any one of claims 1 to 4, wherein the viscosity of said polymer dispersion is 30 to 1500 mPa·s immediately after and one month after the production.
- The paper strengthening agent according to any one of claims 1 to 5, wherein the dispersibility retaining agent is dimethyldiallylammonium chloride (co)polymer.
- The paper strengthening agent according to any one of claims 1 to 5, wherein the dispersibility retaining agent is an alkyl group-substituted and/or an aralkyl group-substituted polyethylenepolyamine.
- The paper strengthening agent according to claim 7, wherein the dispersibility retaining agent is an alkyl group-substituted and/or an aralkyl group-substituted pentaethylenehexamine, the alkyl group having at least 5 carbon atoms.
- A paper strengthening method comprising the steps of: diluting the paper strengthening agent according to any one of claims 1 to 8 with water to prepare a diluted dispersion, coating or impregnating said diluted dispersion onto a dry paper, and drying the treated dry paper.
- A paper strengthening method comprising the steps of: diluting the paper strengthening agent according to any one of claims 1 to 8 with water to prepare a diluted dispersion, and impregnating said diluted dispersion into wet paper on a wire part.
- The paper strengthening method according to claim 10 wherein said diluted dispersion is sprayed to be impregnated into wet paper.
- The paper strengthening method according to any one of claims 10 and 11, wherein the wet paper treated with said diluted dispersion is of a single layer.
- A paper strengthening method comprising the steps of: diluting the paper strengthening agent according to any one of claims 1 to 8 with water to prepare a diluted dispersion, spraying said diluted dispersion onto a web surface to prepare a plurality of webs having polymer adhered to surfaces thereof, and pressing the surface of said webs so as to be superimposed followed by drying.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12664398A JP3302642B2 (en) | 1998-04-22 | 1998-04-22 | Paper Strengthening Agent and Paper Strengthening Method |
JP12664398 | 1998-04-22 | ||
JP17532898A JPH11350384A (en) | 1998-06-09 | 1998-06-09 | Surface coating agent for paper |
JP17532898 | 1998-06-09 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0953679A1 true EP0953679A1 (en) | 1999-11-03 |
EP0953679B1 EP0953679B1 (en) | 2002-09-11 |
Family
ID=26462808
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98111753A Expired - Lifetime EP0953679B1 (en) | 1998-04-22 | 1998-06-25 | Paper strengthening agent and paper strengthening method |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0953679B1 (en) |
DE (1) | DE69807843T2 (en) |
ES (1) | ES2185086T3 (en) |
NO (1) | NO323070B1 (en) |
RU (1) | RU2146317C1 (en) |
TW (1) | TWI224641B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101210403B (en) * | 2007-12-21 | 2010-08-11 | 陕西科技大学 | Method for preparing ring crush intensity synergist of full waste paper corrugated base paper |
WO2019076702A1 (en) | 2017-10-18 | 2019-04-25 | Basf Se | Method for producing multi-layer paper |
WO2019076703A1 (en) | 2017-10-18 | 2019-04-25 | Basf Se | Method for producing single-layer or multi-layer paper |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2999038A (en) * | 1958-01-24 | 1961-09-05 | Rohm & Haas | Method of producing wet-strength papers |
EP0036993A1 (en) * | 1980-03-28 | 1981-10-07 | Wolff Walsrode Aktiengesellschaft | Process for ennobling paper and paper-board |
JPS60185900A (en) * | 1984-03-01 | 1985-09-21 | 星光化学工業株式会社 | Papermaking method |
US5045587A (en) * | 1988-12-12 | 1991-09-03 | Kyoritsu Yuki Co., Ltd. | Method of maintaining flowability of acrylic polymer dispersion |
EP0717056A2 (en) * | 1994-12-15 | 1996-06-19 | Hymo Corporation | An aqueous dispersion of an amphoteric water-soluble polymer, a method of manufacturing the same, and a treating agent comprising the same |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0614907A (en) * | 1992-06-30 | 1994-01-25 | Shimadzu Corp | Measuring system using light absorption |
-
1998
- 1998-06-25 ES ES98111753T patent/ES2185086T3/en not_active Expired - Lifetime
- 1998-06-25 EP EP98111753A patent/EP0953679B1/en not_active Expired - Lifetime
- 1998-06-25 DE DE1998607843 patent/DE69807843T2/en not_active Expired - Lifetime
- 1998-07-01 RU RU98113153A patent/RU2146317C1/en not_active IP Right Cessation
- 1998-07-03 NO NO19983091A patent/NO323070B1/en not_active IP Right Cessation
-
1999
- 1999-10-29 TW TW88118763A patent/TWI224641B/en not_active IP Right Cessation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2999038A (en) * | 1958-01-24 | 1961-09-05 | Rohm & Haas | Method of producing wet-strength papers |
EP0036993A1 (en) * | 1980-03-28 | 1981-10-07 | Wolff Walsrode Aktiengesellschaft | Process for ennobling paper and paper-board |
JPS60185900A (en) * | 1984-03-01 | 1985-09-21 | 星光化学工業株式会社 | Papermaking method |
US5045587A (en) * | 1988-12-12 | 1991-09-03 | Kyoritsu Yuki Co., Ltd. | Method of maintaining flowability of acrylic polymer dispersion |
EP0717056A2 (en) * | 1994-12-15 | 1996-06-19 | Hymo Corporation | An aqueous dispersion of an amphoteric water-soluble polymer, a method of manufacturing the same, and a treating agent comprising the same |
Non-Patent Citations (1)
Title |
---|
DATABASE WPI Section Ch Week 8544, Derwent World Patents Index; Class A14, AN 85-273498, XP002109240 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101210403B (en) * | 2007-12-21 | 2010-08-11 | 陕西科技大学 | Method for preparing ring crush intensity synergist of full waste paper corrugated base paper |
WO2019076702A1 (en) | 2017-10-18 | 2019-04-25 | Basf Se | Method for producing multi-layer paper |
WO2019076703A1 (en) | 2017-10-18 | 2019-04-25 | Basf Se | Method for producing single-layer or multi-layer paper |
US11680371B2 (en) | 2017-10-18 | 2023-06-20 | Solenis Technologies, L.P. | Method for producing multi-layer paper |
Also Published As
Publication number | Publication date |
---|---|
ES2185086T3 (en) | 2003-04-16 |
RU2146317C1 (en) | 2000-03-10 |
NO983091D0 (en) | 1998-07-03 |
NO983091L (en) | 1999-10-25 |
NO323070B1 (en) | 2006-12-27 |
DE69807843D1 (en) | 2002-10-17 |
EP0953679B1 (en) | 2002-09-11 |
TWI224641B (en) | 2004-12-01 |
DE69807843T2 (en) | 2003-05-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8278374B2 (en) | Processes for manufacture of a dry strength paper and methods for imparting dry strength to paper using a cationic starch graft polymer | |
FI110386B (en) | A composition for coating papers containing substantially alkaline swelling latex | |
KR101836210B1 (en) | Surface application of polymers to improve paper strength | |
WO2005072185A2 (en) | Method of using aldehyde-functionalized polymers to enhance paper machine dewatering | |
US4189345A (en) | Fibrous compositions | |
CA1100269A (en) | Creping paper using cationic water soluble polymer | |
RU2347865C2 (en) | Application of water-soluble stitched cation-active polymers for suppression of resin and sticky materials deposits creation in manufacture of paper | |
JPS6225781B2 (en) | ||
EP0953679B1 (en) | Paper strengthening agent and paper strengthening method | |
JP5637527B2 (en) | Paper making method | |
JP2005226200A (en) | Paper making method | |
CA2904596C (en) | Method of using aldehyde-functionalized polymers to increase papermachine performance and enhance sizing | |
KR100650355B1 (en) | Paper strengthening agent and paper strengthening method | |
CA2679740C (en) | Blends of anionic copolymers suitable for surface size and methods of making the same | |
JP3354646B2 (en) | Polyvinyl alcohol resin composition | |
JP4395817B2 (en) | Method for producing surface sizing agent and coated paper | |
CN1294227A (en) | Paper reinforcing agent and paper reinforcing method | |
EP0014534B1 (en) | Preparation of hydrophilic polyolefin fibres and paper containing these fibres | |
JP3260297B2 (en) | Delamination inhibitor and delamination prevention method | |
JP3302642B2 (en) | Paper Strengthening Agent and Paper Strengthening Method | |
KR101123548B1 (en) | Dispersin agent for paper pulp | |
CA1118165A (en) | High strength composites and a method for forming | |
KR100508069B1 (en) | Polymer dispersion, preparation method thereof and use thereof | |
JPH11323766A (en) | Paper particle-antisticking agent for water doctor for press roll and method for antisticking of paper particle | |
WO2024129932A1 (en) | Improved retention of engineered cellulosic additives using synergistic cationic polymer combination |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): DE ES FI FR GB IT NL SE |
|
AX | Request for extension of the european patent |
Free format text: AL;LT;LV;MK;RO;SI |
|
17P | Request for examination filed |
Effective date: 19991214 |
|
AKX | Designation fees paid |
Free format text: DE ES FI FR GB IT NL SE |
|
17Q | First examination report despatched |
Effective date: 20001211 |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE ES FI FR GB IT NL SE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20020911 Ref country code: IT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED. Effective date: 20020911 |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
REF | Corresponds to: |
Ref document number: 69807843 Country of ref document: DE Date of ref document: 20021017 |
|
ET | Fr: translation filed | ||
NLV1 | Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act | ||
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FG2A Ref document number: 2185086 Country of ref document: ES Kind code of ref document: T3 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed |
Effective date: 20030612 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FI Payment date: 20090528 Year of fee payment: 12 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20100625 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: ES Payment date: 20120628 Year of fee payment: 15 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20130620 Year of fee payment: 16 Ref country code: SE Payment date: 20130620 Year of fee payment: 16 Ref country code: DE Payment date: 20130423 Year of fee payment: 16 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20130703 Year of fee payment: 16 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R119 Ref document number: 69807843 Country of ref document: DE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20140626 |
|
REG | Reference to a national code |
Ref country code: SE Ref legal event code: EUG |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20140625 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R119 Ref document number: 69807843 Country of ref document: DE Effective date: 20150101 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST Effective date: 20150227 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20150101 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20140625 Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20140630 |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FD2A Effective date: 20150728 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: ES Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20140626 |