JP2005232604A - Bulkiness reduction inhibitor, paper making method, and paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain bulky high quality paper having both good bulkiness and high inner strength. <P>SOLUTION: The subject bulkiness reduction inhibitor for paper is characterized by comprising an un-gelatinized starch aqueous slurry for being added to a paper material to give a starch solid content concentration of 0.5 to 15 mass % based on the solid content of pulp in the paper material. The paper making method comprises adding the bulkiness reduction inhibitor to the paper material and then subjecting the paper material to a dehydration process, a pressing process, and a drying process. The paper is produced by this method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bulk reduction inhibitor for producing a bulky paper having high internal strength, a papermaking method using the bulk reduction inhibitor, and a bulky paper produced by the papermaking method.

  In recent years, the recycling of waste paper has been promoted due to the rise in pulp prices, the effective use of resources and the need for environmental protection. At the same time, in order to minimize the amount of pulp used, the basis weight of paper products has been reduced. An effort is being made to lower it. However, as waste paper recycling is promoted, the fiber blended in the papermaking raw material is in the direction of miniaturization, and the thickness (bulkness) and strength of the paper are difficult to produce, which causes the paper quality to deteriorate. There was a problem that.

  Under such circumstances, in order to obtain a bulky and high-quality paper, an operation of increasing the basis weight of the paper is performed. However, increasing the basis weight of the paper increases the amount of pulp to be used, which is not preferable from the viewpoint of environmental protection, and increases in production cost are inevitable as the price of used paper increases. From such a background, there has been a demand for a method capable of producing a bulky and high-quality paper from a raw material with a high waste paper content ratio or a raw material with a low pulp content.

  As a method for producing bulky paper, a physical method for reducing external pressure such as press pressure in the paper making process, a method for physically fluffing pulp fibers to increase the bulkiness of the pulp, and reacting a pulp with a crosslinking agent Methods (Patent Documents 1 and 2), bulking agents such as ester compounds of polyhydric alcohols and fatty acids and bulking agents using compounds obtained by adding oxyalkylene groups to the ester compounds (Patent Documents 3 and 4), cationic compounds, A bulking agent using an amine, an amine, an ammonium salt and an amphoteric compound (Patent Document 5), or a bulking agent containing various nonionic surfactants and an anionic surfactant (Patent Documents 6 to 8). And the like. These methods may cause disadvantages such as deterioration in operability, increase in energy costs, and difficulty in recycling paper, but they can be said to exhibit certain effects in terms of increasing the bulk of paper. However, increasing the bulk of the paper is reducing the density of the paper, so in any method, a decrease in paper strength, particularly a decrease in internal strength, is an unavoidable problem. It is bulky and has high internal strength. It was difficult to produce paper having

  On the other hand, as a method for improving the internal strength of paper, there is a method of adding a paper strength enhancer composed of various water-soluble polymers to the paper stock. Examples of the paper strength enhancer include various types of starch pastes of cationic or amphoteric, or synthetic synthetic materials such as cation-modified polyacrylamide (PAM), cation-modified poly (meth) acrylate, polyethylene oxide (PEO), and polyvinyl alcohol (PVA). Molecules are used. When added to the stock, these paper strength enhancers adsorb to the pulp fibers, strengthening the adsorption between the fibers, and forming a stronger inter-fiber bond in the pressing and drying processes to make the sheet a dense structure. To improve paper strength. That is, these paper strength enhancing agents have the effect of improving paper strength by increasing the density of the paper, and consequently act in the direction of reducing the bulk of the paper. In addition, in papers that require higher strength, such as corrugated cardboard and paperboard, it is necessary to add more paper strength enhancers, which not only further reduces the bulk of the paper but also reduces drainage and texture. As a result, the adverse effects on the operation were unavoidable. Therefore, with these paper strength enhancing agents, it is difficult to improve the internal strength of the paper while maintaining the bulk of the paper. Furthermore, when these paper strength enhancing agents are used in the above-described methods for producing various bulky papers, not only the effects of various treatments for making the paper bulky are lost, but also energy costs are wasted and chemical unit consumption is increased. This will also cause problems, and will lead to results that are contrary to the goals of environmental conservation and recycling society construction in the paper industry.

  As an internally added paper strength enhancer to be added to the paper stock, an aqueous slurry of a so-called self-fixing starch in which a high molecular weight cationic polymer is adsorbed on the surface of an anionic starch, in addition to the aforementioned water-soluble polymer, There is a technique (Patent Document 9) used as In addition to this, as a technique for improving the strength of paper, a technique of internally adding cationic starch in a slurry state (patent document 10) obtained by subjecting starch to a heat treatment in a dry manner in the presence of a cationic polymer at a high temperature, There is a technique (Patent Document 11) for internally adding a coagulated starch slurry containing starch particles, a cationic polymer flocculant, and an anionic inorganic colloid such as bentonite. However, the bulk and strength of paper are contradictory characteristics, and it has been difficult to achieve both of these characteristics by the conventional internal addition method of a paper strength enhancer.

  As another method for improving the internal strength of paper, there is a spray method in which an ungelatinized starch slurry is sprayed on a wet paper or between wet paper layers. In this method, a relatively large amount of starch can be applied to the paper, and as a result, a high-strength paper can be obtained. However, there are problems such as the need for strict maintenance and maintenance of the spray nozzle to perform spraying without interruption, the need to install a spray device, and the sprayed starch slurry mist droplets easily contaminating the paper machine. There is a point.

A surface sizing method is widely used as a method for improving the surface strength of paper, and is effective in improving internal strength. However, in the process of applying a sizing liquid such as starch paste on the paper surface, pressure is applied to the paper and the density of the paper tends to increase as the amount of sizing liquid increases. It will be difficult to do. Therefore, it is difficult to apply the size liquid and maintain the bulk at a high level with the current application technique. Further, the surface size method not only reduces the bulk, but also has a demerit that a coating device such as a size press is required.
Japanese Patent Laid-Open No. 4-185791 Japanese Patent Laid-Open No. 4-185792 JP 2000-034691 A JP 11-350380 A JP-A-11-269799 JP-A-11-200263 JP-A-11-200284 JP-A-11-200285 JP 2000-226401 A JP-A-9-291103 JP-T-2001-504174

  Accordingly, an object of the present invention is to obtain a bulky high quality paper having both bulkiness and high internal strength. In particular, an object of the present invention is to obtain a bulky and high-quality paper in a papermaking process for paperboard that requires high internal strength.

As a result of intensive studies to achieve the above object, the present inventors have surprisingly found that the starch solid content concentration is 0.5 to 15% by mass with respect to the pulp solid content in the paper stock. Furthermore, it has been found that by using an aqueous slurry of ungelatinized starch as a bulk reduction inhibitor, a bulky and high quality paper can be obtained, and the present invention has been completed.
That is, the above object of the present invention is achieved by the following means.
[Claim 1] It is characterized by comprising an aqueous slurry of ungelatinized starch contained in the paper stock so that the starch solid content concentration relative to the pulp solid content in the paper stock is in the range of 0.5 to 15% by mass. Paper bulk reduction inhibitor.
[Claim 2] The bulk reduction inhibitor according to claim 1, which is a bulk reduction inhibitor for paperboard.
[Claim 3] The bulk reduction inhibitor according to claim 1 or 2, which is used for improving the internal strength while maintaining the bulk of the paper.
[Claim 4] The bulk reduction inhibitor according to any one of claims 1 to 3, which is added to the stock during papermaking.
[5] The bulk reduction inhibitor according to any one of [1] to [4], which is used in a papermaking system using a bulking agent for papermaking internal addition.
[Claim 6] The bulk reduction inhibitor according to any one of claims 1 to 5, wherein the starch is a self-fixing starch in which a high molecular weight cationic polymer is adsorbed on the surface of an anionic starch.
[7] A bulk reduction inhibitor according to any one of [1] to [6] is added to a stock, and then the stock is subjected to a dehydration step, a press step, and a drying step. Paper making method.
[8] The method according to [7], wherein the paper stock includes pulp imparted with bulkiness by performing physical treatment and / or chemical treatment.
[9] A paper produced by the method according to any one of [6] to [8].

  According to the present invention, it is possible to produce a bulky and high-quality paper, particularly a paperboard that is bulky and has high internal strength.

Hereinafter, the present invention will be described in more detail.
The bulk reduction inhibitor of the present invention comprises an aqueous slurry of ungelatinized starch. The mechanism by which the bulk reduction inhibitor of the present invention can improve the internal strength of the paper while maintaining the bulk is considered as follows.
For example, when a water-soluble polymer is used as a paper strength enhancer, the added water-soluble polymer is adsorbed over a wide range of pulp fibers and promotes adsorption between fibers. In the process of forming the sheet, the bond between the pulp fibers becomes strong, and a paper having a high density is formed. Therefore, in such a case, it is difficult to produce a bulky and high strength paper.

  On the other hand, the bulk reduction inhibitor of the present invention comprising an aqueous slurry of ungelatinized starch is present as insoluble particles because it is in an aqueous slurry state when added to the stock. When this is added to the stock, it is fixed to the pulp fiber by ionic adsorption or entanglement with physical fibers, but the fixed starch particles are very coarse compared to the water-soluble polymer. There is no effect of promoting adsorption between fibers. Therefore, even if this paper stock is dehydrated and pressed, a sheet is formed with the pulp fibers remaining in a sparse state. After that, in the drying process, the starch particles contained in the wet sheet are gelatinized and dispersed in the sheet by moisture and heat of drying in the sheet, and penetrate into a wide range between the pulp fibers, so that the inside of the paper Strength can be improved. Furthermore, the bulk reduction inhibitor of the present invention has a high internal strength without hindering the effects of various bulky treatments by the same mechanism as described above even in a papermaking system using bulked pulp or a bulking agent for papermaking. Improvements can be achieved, making it possible to produce more bulky and high quality paper.

  The starch used for the bulk reduction inhibitor comprising the aqueous slurry of ungelatinized starch of the present invention is not particularly limited. For example, cationization treated with raw starch, various cationizing agents or cationic polymers Any commercially available starch such as starch, oxidized starch, esterified starch, etherified starch, and self-fixing starch having a cationic polymer adsorbed on the surface thereof can be used. In particular, it is preferable to use starch that has been processed so as to be easily fixed to pulp fibers in an aqueous slurry state and to be easily gelatinized in the drying step. As such starch, self-fixing starch having a high molecular weight cationic polymer adsorbed on the surface of anionic starch particles can be used, and among them, 20% aqueous solution having a concentration of 0.2% by weight is formed on the surface of anionic starch particles. It is particularly preferable to use self-fixing starch in which a high molecular weight cationic polymer having a B-type viscosity at 10 ° C. and 60 rpm of 10 mPa · s or more is adsorbed as a solid content per starch solid content of 100 to 20,000 ppm.

  Anionic starch used as a raw material for the self-fixing starch is starch having an anion on the particle surface. The anionization degree is preferably set as appropriate in consideration of the degree of cationization of the cationic polymer to be adsorbed, and is preferably 0.01 meq / g or more, for example. When the anionization degree is 0.01 meq / g or more, the cationic polymer is adsorbed satisfactorily, and is easily fixed to the pulp fiber in the state of an aqueous slurry, and obtains a self-fixing starch that is easily gelatinized and dispersed in the drying process. be able to. The degree of anionization is preferably 0.03 to 0.5 meq / g.

The anionic starch is preferably an anionic starch having a solid content concentration of 1 to 20% by mass of a starch paste solution that gives a B-type viscosity of 50 mPa · s at 50 ° C. and 60 rpm. The solid content concentration of the anionic starch is determined by solidifying the aqueous slurry of the anionic starch at 95 ° C. for 30 minutes and then cooling to 50 ° C. when the B-type viscosity at 60 rpm is 50 mPa · s. It is determined by measuring the concentration.
If the solid content concentration of the anionic starch paste showing a B-type viscosity of 50 mPa · s at 50 ° C. and 60 rpm is in the range of 1 to 20% by mass, the starch has a relatively high molecular weight, and thus the strength of the starch itself is high. In addition, when the starch fixed in the paper layer in the dehydration process is gelatinized and dispersed in the drying process, the starch stays inside the paper without migrating to the surface of the paper and strengthens the bonds between the fibers, resulting in high internal strength. An improvement effect can be obtained. If it is above this range, the starch will have a very low molecular weight, so not only will the starch migrate in the drying process and the effect of improving the internal strength will decrease, but the cold water soluble component will increase, and starch yield in the dehydration process will increase. There is a risk of causing problems such as a decrease and a decrease in the internal strength improvement effect associated therewith.

  Specific examples of the anionic starch include oxidized starch treated with hypochlorite such as sodium hypochlorite, and starch dibasic acid reacted with dibasic acid anhydride such as succinic anhydride and maleic anhydride. Mention may be made of half esters and starch phosphates treated with phosphoric acid and / or phosphates such as phosphoric acid / urea (in combination), sodium phosphate, sodium tripolyphosphate. Among these, oxidized starch and starch phosphate ester are economically advantageous because anion introduction and viscosity reduction can be achieved almost simultaneously.

  The anionic starch may have a viscosity reduced to a desired level at the same time as anionization. If the viscosity is not reduced to a desired level only by anionization, the anion starch has a low viscosity after anionization. Can be applied. As a method for reducing the viscosity, known methods for reducing the viscosity such as acid hydrolysis, oxidative decomposition, and enzymatic decomposition can be employed. Specific examples of the raw material starch used for the preparation of the anionic starch include corn starch, tapioca starch, potato starch, sweet potato starch, wheat starch, waxy corn starch, and high amylose corn starch, and any commercially available starch can be used.

  The high molecular weight cationic polymer adsorbed on the surface of the anionic starch particles is not particularly limited as long as it can be adsorbed on the surface of the anionic starch particles. For example, those having a cationization degree of 0.2 meq / g or more are preferably used. Specific examples of the high molecular weight cationic polymer include cation-modified polyacrylamide (PAM), polyethyleneimine, cation-modified poly (meth) acrylate, polydiallyldimethylammonium chloride, and chitosan. Among these, from the economical viewpoint, those of cation-modified polyacrylamide type such as diethylaminoethyl methacrylate, diallyldimethylammonium chloride, diallyldiethylammonium chloride, methacryloyloxyethyltrimethylammonium methylsulfate, methacryloyloxyethyltrimethylammonium chloride, methacrylic acid. A copolymerized PAM obtained by copolymerizing a cationic monomer such as amidopropyltrimethylammonium chloride, a Mannich-modified PAM, a Hoffman-decomposed PAM, and the like are preferable. Further, in addition to the cation, it may have a substituent of nonion or anion (in a range where the degree of net cationization does not fall below 0.2 meq / g, for example).

The molecular weight of the high molecular weight cationic polymer adsorbed on the surface of the anionic starch particles can be, for example, in the range of 10,000 to 20 million.
However, it is difficult to accurately measure the molecular weight of a polymer having a very high molecular weight, and errors due to the measurement method are large. Therefore, in the present invention, the aqueous solution viscosity is used as an index of molecular weight. That is, the high molecular weight cationic polymer used in the present invention is preferably a high molecular weight cationic polymer having a B-type viscosity of 10 mPa · s or more at 20 ° C. and 60 rpm in an aqueous solution having a concentration of 0.2% by mass. It is more preferable to use a high molecular weight cationic polymer having a viscosity in the range of 30 to 500 mPa · s. This aqueous solution viscosity is a value obtained by measuring the B-type viscosity at 20 ° C. and 60 rpm of an aqueous solution having a concentration of 0.2% by mass by diluting or dissolving the cationic polymer with distilled water. When a high molecular weight cationic polymer having a B-type viscosity of 10 mPa · s or more, preferably 30 to 500 mPa · s is used, the cationic polymer adsorbed on the starch is adsorbed in a wide range with the pulp fiber, and the starch is formed in the paper layer in the dehydration process. It can be fixed efficiently. On the other hand, the use of high molecular weight cationic polymers with viscosities exceeding this range increases the fixability to pulp fibers, but causes significant aggregation of starch particles, causing starch to be fixed non-uniformly within the paper layer and improving efficiency. There is a risk that it will be difficult to achieve an increase in internal strength.

  As a method for obtaining a self-fixing starch by adsorbing a cationic polymer to an anionic starch, an aqueous slurry in which an anionic starch is suspended in water and an aqueous solution of the cationic polymer are brought into contact with each other, and sufficient to adsorb the cationic polymer to the anionic starch. A time holding method can be used, and the specific method is not particularly limited. The simplest method is a method in which an aqueous cationic polymer solution or a powdered cationic polymer is added to an aqueous slurry of anionic starch and sufficiently stirred.

  The adsorption amount of the high molecular weight cationic polymer on the surface of the anionic starch particles is preferably in the range of 100 to 20,000 ppm, more preferably in the range of 500 to 10,000 ppm as the solid content per starch solid content. When the adsorption amount is within the above range, efficient adsorption to the pulp fiber and uniform fixing in the paper layer, that is, efficient internal strength improvement can be achieved. Above this range, the starch particles can cause significant aggregation and non-uniform fixation within the paper layer, as well as excessive cationic polymers can promote the adsorption of pulp fibers and reduce paper bulk. There is.

  When an aqueous slurry of anionic starch is adsorbed with a cationic polymer, it causes some aggregation and temporarily increases the viscosity of the aqueous slurry. Therefore, it is preferable to prepare the aqueous slurry of the anionic starch at the time of producing the self-fixing starch at a concentration at which the slurry can be sufficiently stirred even in the above case, for example, a concentration of 30% or less. Also, if the temperature of the aqueous slurry of anionic starch exceeds the gelatinization start temperature of the anionic starch, the starch will start to swell and the viscosity of the slurry may increase, deteriorating the workability. There is a risk that problems such as deterioration of freeness will occur. From the above viewpoint, the temperature of the aqueous slurry of anionic starch during the production of self-fixing starch is preferably 40 ° C or lower.

  The bulk reduction inhibitor of the present invention can be, for example, an aqueous slurry obtained from the aforementioned self-fixing starch. The aqueous slurry can be prepared by a known method. Moreover, the aqueous slurry of ungelatinized starch that is the bulk reduction inhibitor of the present invention contains gelatinized starch, commercially available synthetic polymers, salts, antifoaming agents, preservatives, etc. in addition to ungelatinized starch. You can also. Although the starch density | concentration in the said aqueous slurry is not specifically limited, When workability | operativity is considered, it can be made into the range of 1-40%, for example, Preferably 5-30%.

  The bulk reduction inhibitor of the present invention can be added to a paper stock during paper making. More specifically, the bulk reduction inhibitor of the present invention can be added to the stock before paper making. Thereafter, a paper stock containing the bulk reduction inhibitor of the present invention is subjected to a dehydration step, a press step, and a drying step, whereby a bulky and high-quality paper can be produced.

  The bulk reduction inhibitor of the present invention is a paper stock so that the starch solid content concentration with respect to the pulp solid content in the paper stock is 0.5 to 15%, preferably 1 to 5% on a mass basis. It is contained in the inside. If the starch solid content concentration in the paper stock is within the above range, it becomes possible to fix a sufficient amount of starch in the paper layer to improve the internal strength of the paper while maintaining the bulk of the paper. . On the other hand, if the starch solid content concentration in the stock is less than 0.5% by mass, a paper having high internal strength cannot be obtained, and if the starch solid content concentration in the stock exceeds 15% by mass, the density It causes a rise and it becomes difficult to obtain a bulky and high quality paper. The bulk reduction inhibitor of the present invention can be added to a stock prepared by adding chemicals for papermaking as described later to the raw pulp liquid, and the raw pulp liquid before the addition of chemicals for papermaking It can also be added. It should be noted that “added to the paper stock” described below includes addition to the raw material pulp liquid before adding the chemical for papermaking.

  In the present invention, the raw material pulp used for producing paper includes ground wood pulp (GP), pressurized ground wood pulp (PGW), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), semi-chemical pulp (SCP). ) And other mechanical pulp (MP), chemical pulp (AP, KP), deinked pulp (DIP), recovered pulp obtained from process waste paper generated in the paper making process, etc. Can be blended into the paper stock at an arbitrary ratio according to the required quality. In order to make a paper having a higher bulk, it is also preferable to use a pulp imparted with a bulk by performing a physical treatment or a chemical treatment. Examples of such a pulp include a physically fluffed pulp, a pulp reacted with a crosslinking agent, and the like. The bulk reduction inhibitor of the present invention is used in a papermaking system that uses a large amount of waste paper raw material that has been disaggregated twice or more like DIP or recovered pulp, and has become difficult to produce bulk. The effect of improving the strength can be exhibited more remarkably.

  When paper is made, commercially available chemicals for papermaking such as water-soluble aluminum compounds, sizing agents, fillers, yield improvers, and freeness improvers may be added to the paper stock. Among them, the yield improver and the drainage improver are often made of a water-soluble polymer, and they are added in order to promote the adsorption of fibers in the paper and facilitate the formation of a dense sheet. In such a case, it is preferable to use at a low addition rate of 1% or less with respect to the pulp raw material.

  The addition of a bulking agent for internal addition during papermaking is effective for papermaking of bulky paper. When the bulk reduction inhibitor of the present invention and the bulking agent are used in combination, the addition ratio of the bulking agent in the paper stock is preferably 0.1 to 1.5% by mass, more preferably 0, based on the pulp solid content. .2 to 1.0% by mass. In that case, it is preferable to add the bulk reduction inhibitor of the present invention so that the starch solid content concentration is 0.5 to 15% by mass, and 1.0 to 5% by mass with respect to the pulp raw material. More preferably. The bulking agent used in combination is not particularly limited. For example, a bulking agent, a cationic compound, an amine, an ammonium salt and an amphoteric compound using an ester compound of a polyhydric alcohol and a fatty acid and a compound obtained by adding an oxyalkylene group to the ester compound are used. Bulking agents, bulking agents containing various nonionic surfactants and anionic surfactants, bulking agents having a hydrophobic group, polyamine group, glycidyl group structure, amino having an acetal group bonded to an amino group A bulking agent containing a compound as an active ingredient can be used.

  The bulk reduction inhibitor of the present invention exerts its effect by being added in the paper making process before the dehydration and pressing process in which the paper is filtered to form a sheet while traveling on the wire of the paper machine. be able to. For example, it is desirable to add the bulk reduction inhibitor of the present invention such as a refiner, a machine chest, a seed box, or a head box at a place where it can be uniformly blended with the pulp raw material. In the present invention, the order of addition of the bulk reduction inhibitor of the present invention and other chemicals for papermaking is not particularly limited.

  The drying step is preferably performed under such conditions that the starch particles contained in the sheet are efficiently gelatinized and dispersed. For example, the temperature inside the sheet is 50 ° C. or more, more preferably moisture in the sheet is Desirably, the drying is performed under such a condition that the temperature inside the sheet reaches 70 ° C. or more in a state of 50% or more. If the moisture inside the sheet is 50% or more and the temperature inside the sheet is 50 ° C. or more, starch can be gelatinized and dispersed well, and a paper having high internal strength as well as bulkiness can be obtained.

  The paper obtained by adding the bulk reduction inhibitor of the present invention to a stock and then subjecting the stock to a dehydration step, a pressing step, and a drying step has both bulkiness and internal strength. That is, the bulk reduction inhibitor of the present invention can be used to improve the internal strength while maintaining the bulk of the paper and to obtain a high-quality paper. Here, “high quality paper” refers to any paper having a high internal strength. "Improving internal strength" means strengthening the bond between pulp fibers in paper, improving paper strength and improving quality, and contributing to the suppression of paper breaks in the papermaking process It means to do. The internal strength of the paper can be evaluated by any means including a burst strength test method and a tensile strength test method defined by the Japanese Standards Association (JIS). As described above, it is generally possible to improve the internal strength by an internal addition method of a water-soluble polymer, but these methods reduce the bulk of the paper. Therefore, the “state in which the bulk of the paper is maintained” as used herein refers to a state in which a decrease in the bulk of the paper caused by the internal addition method of the water-soluble polymer is suppressed, that is, when these internal strength improvement treatments are not performed. It shows that a paper bulk comparable to that of the paper obtained is obtained.

  The density of the paper is, for example, a paper obtained by the same production method except that the internal strength improving process having the effect of reducing the bulk of the paper, such as an internal addition method of a water-soluble polymer and a surface size method, is not performed. When the density is 100%, the density change rate can be 102% or less, preferably 101% or less. Further, the internal strength of the paper can be 100% or more as the rate of change in internal strength when the internal strength of the blank is set to 100% as described above, and is preferably 103% or more. By using the bulk reduction inhibitor of the present invention, it is possible to obtain high-quality paper having both the bulkiness in the above range and the internal strength.

  The bulky high-quality paper produced according to the present invention can be coated with a size liquid such as starch paste or PVA solution by a size press or the like. Performing such a treatment is effective in achieving higher internal strength and imparting printability, although reduction in bulk due to physical pressure and applied size liquid is inevitable.

  The paper bulk reduction inhibitor of the present invention can be widely used for paper in general, and particularly when used for paperboard, the effect of improving the internal strength while maintaining the paper bulk can be significantly obtained. it can. Here, the “paperboard” means a base paper whose rigidity is the most important characteristic, and specific examples thereof include corrugated baseboard, white paperboard, paperboard basepaper, building material basepaper, and paper tube basepaper. However, the paper which can use the bulk reduction inhibitor of the present invention is not limited to these paperboards. The bulk reduction inhibitor of the present invention is used when it is required to satisfy both bulk and internal strength in terms of quality and production in all papers such as book paper, newspaper winding paper, coated paper, kraft paper, and PPC paper. Is possible.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The “%” shown below is based on the mass of the pulp solids unless otherwise specified. Moreover, the "blank" as described below shows the sample made by the same prescription as an Example or a comparative example except not adding the component shown as a bulk reduction inhibitor for internal addition shown in Tables 1-4. . The paper obtained in Examples and Comparative Examples was evaluated by the following method.
(1) Density Measured according to JIS P 8118. Moreover, the density change rate when the density of the blank was set to 100% was calculated from the obtained value. The difference in density change rate of 1% is fully recognized as a dominant difference.
(2) Specific compression Measured according to JIS P 8126.
(3) Specific burst It measured according to JIS P8112.
(4) Breaking length Measured according to JIS P8113.
(5) Internal bond JAPAN TAPPI No. Measurement was performed according to 54.

[Examples 1-7]
Pulp slurry made of 100% corrugated paper is adjusted to 2% with city water, and 2% of sulfuric acid band (manufactured by Sumitomo Chemical Co., Ltd.) is stirred (a liquid sulfuric acid band containing 8% as aluminum sulfate). 1 minute later, and after 1 minute, an aqueous slurry of self-fixing starch (HR Bond; manufactured by Nippon Food Chemicals Co., Ltd.) or cationic starch (Neotack 40T: manufactured by Nippon Food Chemicals Co., Ltd.) The solid content was added in such an amount as shown in Table 1, and diluted water was added 1 minute later to prepare a paper stock having a pulp concentration of 1.0%.

Using the obtained paper stock, using an experimental square sheet machine (250 mm × 250 mm, manufactured by Kumagai Riki Kogyo Co., Ltd.), with a paper stock concentration of 0.1% and a basis weight of 120 g / m ² A paper sheet was prepared. The first press then 1 kg / cm ² for 2 minutes, after the second press followed 1 kg / cm ² for 1 minute, dried on a rotary evaporator with a surface temperature 130 ° C. 3 minutes to obtain a liner base paper . This was conditioned overnight at 23 ° C. and a relative humidity of 50% and then analyzed. The results are shown in Table 1.

[Comparative Examples 1-6]
As in Examples 1 to 7, while stirring 2% corrugated paper pulp, 2% sulfuric acid band (manufactured by Sumitomo Chemical Co., Ltd.) was converted to 100% as a liquid sulfuric acid band containing 8% as aluminum sulfate. 1 minute later, an aqueous solution of amphoteric PAM (Polystron 1224; manufactured by Arakawa Chemical Co., Ltd.) or amphoteric starch (Cato 3210; manufactured by Nippon NSC Co., Ltd.) was added to the concentration shown in Table 1. 1 minute later, diluted water was added to prepare a paper stock having a pulp concentration of 1.0%. A liner base paper was produced in the same manner as in Examples 1 to 7 using the obtained paper stock. The analysis results of the liner base paper are shown in Table 1.

  From Table 1, Examples 1 to 7 using the bulking agent of the present invention consisting of an aqueous slurry of ungelatinized starch are Comparative Examples 1 to 7 using aqueous solutions of water-soluble polymers such as amphoteric PAM and amphoteric starch paste. On the other hand, it can be seen that the improvement in internal strength was achieved in a low density state, that is, in a bulky state. On the other hand, Comparative Examples 1 to 6 to which an aqueous solution of a water-soluble polymer such as amphoteric starch or amphoteric PAM is added cause an increase in density (decrease in bulk) depending on the addition rate, although the internal strength is improved.

[Examples 8 to 15]
Pulp slurry consisting of 70 parts DIP from magazine waste paper and 30 parts hardwood bleached pulp (LBKP) was adjusted to 2% concentration with city water, and 1% sulfuric acid band (manufactured by Sumitomo Chemical Co., Ltd.) was stirred. A liquid sulfuric acid band containing 8% as aluminum is converted to 100%), and after 1 minute, an aqueous slurry of self-fixing starch (HR bond; manufactured by Nippon Food Chemical Co., Ltd.) is added. It added in the quantity used as the density | concentration shown in Table 1, and also 0.5% of sizing agents (Harsize NES-405; Harima Kasei Co., Ltd. product) were added after 1 minute. After further stirring for 1 minute, 0.5% of bulking agent (BK-115; manufactured by Kao Corporation or Sulsol VL; manufactured by BASF Japan Corporation) was added, and 1 minute later, dilution water was added to obtain a pulp concentration. A 1.0% strength paper stock was prepared.

Using the obtained paper stock, using an experimental square sheet machine (250 mm × 250 mm, manufactured by Kumagai Riki Kogyo Co., Ltd.), with a paper stock concentration of 0.1% and a basis weight of 140 g / m ² as a target A paper sheet was prepared. Subsequently, after pressing for 2 minutes at 1 kg / cm ² , the paper was dried for 2 minutes with a rotary dryer having a surface temperature of 130 ° C. to obtain a handmade paper. This was conditioned overnight at 23 ° C. and a relative humidity of 50% and then analyzed. The results are shown in Table 2.

[Comparative Examples 7 to 18]
As in Examples 8 to 11, while stirring 2% pulp slurry (DIP: LBKP = 70: 30), 1% sulfuric acid band (manufactured by Sumitomo Chemical Co., Ltd.) was liquid (containing 8% as aluminum sulfate). 1 minute later, and after 1 minute, an aqueous solution of amphoteric PAM (Harmide EX-200; manufactured by Harima Kasei Co., Ltd.) or amphoteric starch (Cato3210; manufactured by Nippon NSC Co., Ltd.) was added. Alternatively, the amphoteric starch solids concentration was added in an amount such that the concentration shown in Table 2 was added, and 0.5% of a sizing agent (Harsize NES-405; manufactured by Harima Kasei Co., Ltd.) was further added after 1 minute. After further stirring for 1 minute, 0.5% of bulking agent (BK-115; manufactured by Kao Corporation or Sulsol VL; manufactured by BASF Japan Corporation) was added, and 1 minute later, dilution water was added to obtain a pulp concentration. A 1.0% strength paper stock was prepared. Handmade paper was produced in the same manner as in Examples 8 to 11 using the obtained paper stock. Table 2 shows the analysis results of the handmade paper.

  From Table 2, in Examples 8-15 using the bulk reduction inhibitor of the present invention consisting of an aqueous slurry of ungelatinized starch in a papermaking system using a bulking agent, water solubility such as amphoteric PAM and amphoteric starch paste solution It can be seen that the internal strength was improved in a low density state, that is, in a bulky state, as compared with Comparative Examples 7 to 18 using an aqueous polymer solution. On the other hand, Comparative Examples 7 to 18 to which an aqueous solution of a water-soluble polymer such as amphoteric PAM or amphoteric starch was added caused an increase in density (decrease in bulk) depending on the addition rate, although the internal strength was improved. It turns out that the effect of the agent has disappeared.

  According to the present invention, in particular, a paperboard requiring a high internal strength can be produced in a bulky and high quality, which can greatly contribute to the reduction of the amount of pulp used and the establishment of an environmental recycling society.

Claims (9)

Paper bulk characterized by comprising an aqueous slurry of ungelatinized starch contained in the paper stock so that the starch solid content concentration relative to the pulp solid content in the stock is in the range of 0.5 to 15% by mass. Reduction inhibitor. The bulk reduction inhibitor according to claim 1, which is a bulk reduction inhibitor for paperboard. The bulk reduction inhibitor according to claim 1 or 2, which is used for improving the internal strength while maintaining the bulk of the paper. The bulk reduction inhibitor according to any one of claims 1 to 3, which is added to the stock during papermaking. The bulk reduction inhibitor according to any one of claims 1 to 4, which is used in a papermaking system using a bulking agent for papermaking. The bulk reduction inhibitor according to any one of claims 1 to 5, wherein the starch is a self-fixing starch having a high molecular weight cationic polymer adsorbed on the surface of an anionic starch. A papermaking method, comprising adding the bulk reduction inhibitor according to any one of claims 1 to 6 to a paper stock, and then subjecting the paper stock to a dehydration step, a press step, and a drying step. The method according to claim 7, wherein the stock includes pulp imparted with bulkiness by performing physical treatment and / or chemical treatment. A paper manufactured by the method according to any one of claims 6 to 8.