JP2006083509A - Method for producing water-disintegrable paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing water-disintegrable paper bulky, having good shape retention against physical loading, such as a load, even when impregnated with an aqueous chemical and made to be in a wet state, strong, and difficult to be broken. <P>SOLUTION: This method for producing the water-disintegrable paper comprises subjecting a fiber sheet to embossing, in such a state that a water content of the fiber sheet is 10-100 wt%, and drying the fiber sheet simultaneously with or immediately after the embossing, wherein the fiber sheet contains a water-soluble binder or a water-swelling binder, is substantially dispersible in water, and has a basis weight of 30-150 g/m<SP>2</SP>. The fiber sheet is preferably impregnated with the aqueous chemical, after the fiber sheet is dried. It is preferable that the embossing is conducted by using a pair of embossing rolls having concave and convex parts of which the shapes are engaged with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method capable of producing bulky hydrolytic paper.

  The present applicant previously made water disintegration by impregnating a water disintegration paper produced by wet papermaking and containing a water-soluble binder having a carboxyl group with an aqueous cleaning agent containing polyvalent metal ions and an organic solvent as essential components. A cleaning article was proposed (see Patent Document 1). In addition, a water-disintegrable cleaning article produced by wet papermaking and impregnating a water-disintegrating paper containing polyvinyl alcohol as a binder with a boric acid aqueous solution containing a water-soluble solvent has also been proposed (see Patent Document 2). These water-decomposable cleaning articles have a strength that can withstand a cleaning operation, and also have good water-decomposability that allows the water to be discarded in a toilet or the like. The fiber sheet as the base material of these water-degradable cleaning articles is made of a cellulose-based material such as pulp having non-heat-fusible constituent fibers and biodegradability after disposal because it has water-decomposability.

  In order for the water-degrading paper including the water-decomposable cleaning article to be biodegraded after its disposal, it is difficult to mix the heat-fusible fiber, which is usually a fiber having no biodegradability. Some heat-fusible fibers are made of polylactic acid, which is a biodegradable material, but they are expensive and not economical. A typical example of the biodegradable and inexpensive fiber is pulp.

  As a method for making a paper made of fibers mainly composed of pulp or the like bulky, there is an embossing method in which pressing is performed between engraved rolls. The paper embossing method can be broadly divided into a wet embossing method in which embossing is performed on wet paper in the middle of papermaking and a dry embossing method in which embossing is performed after paper making. The wet embossing method is a method in which embossing is performed until paper is dried on a paper machine (see Patent Document 3). Patent Document 3 describes that wet paper subjected to emboss shaping is dried in a drying process. However, in order to dry a large amount of water contained in wet paper during normal paper making, it is necessary to improve the thermal efficiency by bringing the wet paper into strong contact with the surface of the Yanki dryer or multi-cylinder dryer. Bulky embossing was not possible. On the other hand, the dry embossing method is the most general method for embossing paper once made and dried. When embossing is performed on paper mainly composed of non-heat-fusible fibers such as pulp, embossing is performed while the pulp fiber bond (hydrogen bond, bond through binder, etc.) is formed. The bond between fibers and the fiber are broken, and the strength of the paper and the shape retention of the emboss (maintenance of bulk) are lowered.

JP-A-2-149237 JP-A-3-292924 JP-A-8-260397

  Accordingly, an object of the present invention is to provide a method for producing hydrolyzed paper that is less crushed and has good shape retention and can prevent a decrease in strength with respect to the problems of embossing in the paper embossing method described above. .

The present invention provides a fiber sheet having a basis weight of 30 to 150 g / m ² that contains a water-soluble binder or a water-swellable binder and has a water content in the fiber sheet of 10 to 200% by weight. The object is achieved by providing a method for producing hydrolyzed paper, which is embossed in a state and dried at the same time or immediately thereafter.

  In the present invention, a water-soluble binder aqueous solution is added to a sheet containing fibers that do not contain a water-soluble binder and are substantially water-dispersible, and the water-soluble binder content in the sheet is 1 to 30% by weight. And obtaining a fiber sheet having a moisture content of 10 to 200% by weight relative to the weight of the dried sheet, embossing the fiber sheet in this state, and simultaneously or immediately after that, A method for producing hydrolyzed paper to be dried is provided.

  According to the production method of the present invention, the obtained hydrolytic paper can be made bulky. Further, the obtained hydrolytic paper has a good shape retaining property against a physical load such as a load even when it is impregnated with an aqueous chemical and is strong and difficult to tear.

The present invention will be described below based on preferred embodiments with reference to the drawings. The present invention is premised on increasing the thickness by embossing a substantially water-dispersible fiber sheet containing a water-soluble binder or a water-swellable binder. The hydrolyzed paper obtained by embossing a fiber sheet having a basis weight of 30 to 150 g / m ² preferably has a thickness Td measured under a 0.3 kPa load in a dry state. The bulk becomes 0 mm. Furthermore, when the thickness measured under a load of 2.2 kPa is Tw, the thickness ratio (Tw / Td) of the hydrolytic paper after impregnating the aqueous drug with 100 to 500% by weight is preferably It becomes 0.7 or more.

  First, the hydrolytic paper obtained according to the production method of the present invention will be described. FIG. 1 is a perspective view of a hydrolytic paper 1 manufactured according to a preferred embodiment of the present invention. The hydrolytic paper 1 has a first surface 1a and a second surface 1b, and has a large number of convex portions 2, 2... That protrude from one surface side to the other surface side. Yes. The convex portions 2 are arranged at regular intervals so as to form a line in each of the longitudinal direction X and the width direction Y of the hydrolyzed paper 1, and form a staggered arrangement pattern. Recesses 3, 3,... Are respectively formed between the protrusions 2, 2,... To form a staggered arrangement pattern. As a result, the bulk of the water disintegrating paper has a three-dimensional shape as a whole.

  The hydrolytic paper 1 is characterized by its bulkiness. The thickness Td of the hydrolytic paper 1, that is, the distance from the top of the convex portion 2 on the first surface 1a to the top of the convex portion 2 on the second surface 1b is the thickness under a load of 0.3 kPa in the dry state after embossing. Expressed by Td, it is preferably 1.0 to 3.0 mm as described above, and more preferably 1.2 to 2.5 mm. The 0.3 kPa load is very small and approximates the apparent thickness of the hydrolytic paper 1.

  When the hydrolytic paper 1 is impregnated with an aqueous chemical, it is preferable that the hydrolytic paper 1 has a shape retaining property that maintains its thickness even when pressed by applying a certain load in addition to being bulky. In the present invention, for example, the force strongly pressed by the hand is assumed to be 2.2 kPa. When the thickness measured under a 2.2 kPa load of the water-disintegrating paper 1 in the state of being impregnated with the aqueous chemical is Tw, the shape-retaining property is increased as the thickness ratio Tw / Td is closer to 1. This means that the maintainability of the According to the production method of the present invention, a thickness ratio of preferably 0.7 or more is achieved, more preferably 0.75, and even more preferably 0.8 or more. When the thickness ratio is less than 0.7, the shape retention is low, and no difference from the conventional embossing method is observed.

  There is no significant difference in the value of Tw when the amount of the aqueous drug impregnated is in the range of 100 to 500% by weight. For this reason, in the present invention, the amount of impregnation of the aqueous chemical solution is not included in the Tw measurement conditions. If the amount of impregnation of the aqueous chemical solution is included in the Tw measurement conditions, it is appropriate to set it to twice the dry weight of hydrolyzed paper, which is a typical amount of impregnation in the present invention.

  The fiber sheet contains substantially water-dispersible fibers and a water-soluble binder or a water-swellable binder. In order to obtain a hydrolytic paper that maintains its bulkiness and exhibits good wet strength under aqueous drug impregnation, the sheet configuration as described above is essential. The water-soluble binder or water-swellable binder contributes to the development of wet strength under the impregnation of the aqueous drug, the maintenance of the shape retention of the bulky embossed shape, and the water disintegration property when the flush toilet is discarded.

  As the substantially water-dispersible fiber contained in the fiber sheet, those having a fiber length of preferably 15 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less are used. From the viewpoint of achieving both water decomposability and wet strength, it is preferable to mainly use pulp fibers having a weight average fiber length of 0.5 mm to 3.0 mm. Furthermore, rayon fibers and synthetic fibers having an average fiber length of about 4.0 to 7.0 mm can be mixed from the viewpoint of improving the texture. As a kind of fiber, the fiber which has biodegradability is preferable, and a cellulosic fiber is mentioned as a typical thing. Examples of the cellulosic fibers include natural fibers such as pulp and cotton, and semisynthetic fibers such as rayon. These fibers can be used alone or in combination of two or more. Fibrilized fibers with different beating degrees can be used. As pulp, bleached wood pulp such as bleached softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), and other pulp derived from hemp, etc., mercerized pulp subjected to chemical treatment and alkali-swelled, having a spiral structure Chemically crosslinked pulp and fine fibrous cellulose can also be used. In addition, olefin fibers such as polyethylene and polypropylene, which are not biodegradable, and synthetic fibers such as polyester can be used, and synthetic fibers made of polylactic acid are more preferably used because they are biodegradable. The fiber sheet preferably contains 70 to 100% by weight, particularly 80 to 100% by weight of cellulosic fibers excluding the binder.

  Examples of the water-soluble binder include natural polysaccharides, polysaccharide derivatives, and synthetic polymers. Examples of natural polysaccharides include sodium alginate, gum tart, guar gum, xanthan gum, gum arabic, carrageenan, galactomannan, gelatin, casein, albumin, and pull plan. Examples of the polysaccharide derivative include carboxymethylcellulose, carboxyethylcellulose, carboxymethylated denven or a salt thereof, starch, methylcellulose, ethylcellulose and the like. Synthetic polymers include polyvinyl alcohol, polyvinyl alcohol derivatives, unsaturated carboxylic acid polymers or copolymer salts, and copolymers of unsaturated carboxylic acids and monomers copolymerizable with the unsaturated carboxylic acids. And the like. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic anhydride, maleic acid, and fumaric acid. The addition amount of these water-soluble binders can be an appropriate value depending on the use and the type of the binder, but is generally 1 to 30% by weight, particularly 2 to 15% by weight based on the weight of the fiber sheet. % Is preferable from the viewpoint of maintaining bulkiness, developing appropriate wet strength, developing good water disintegration, and economy. In addition, these binders function as a binder that temporarily insolubilizes and maintains the bond between fibers in a state where an aqueous chemical containing water at a high concentration is impregnated in hydrolytic paper. It preferably plays the role of strength maintenance. The water content in the aqueous drug is 30 to 95% by weight, preferably 50 to 95% by weight, and more preferably 60 to 95% by weight. From the viewpoint of sexual properties and irritation to the hand skin.

  Such temporary insolubilization of the water-soluble binder is achieved by the amount of chemical solution impregnated in the hydrolytic paper and the binder insolubilizing component contained in the hydrolytic paper or the aqueous chemical. The amount of the aqueous chemical impregnated into the hydrolytic paper varies depending on the kind and molecular weight of the binder and the content in the hydrolytic paper, and thus cannot be limited. However, it is preferable to impregnate the aqueous chemical at a level at which most of the binder cannot be dissolved. Examples of the insolubilizing component of the binder include a water-soluble organic solvent, a specific acid, an electrolyte, and the like.

  Specific examples of the water-soluble organic solvent include monohydric alcohols such as ethanol, methanol, and isopropyl alcohol, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexylene glycol, and 3-methyl-1. Glycols such as 1,3-butanediol, mono- or diethers of these glycols with lower alcohols such as methanol, ethanol, propanol, and butanol, esters of the glycols with lower fatty acids, and polyhydric alcohols such as glycerin and sorbitol. Can be mentioned. The water-soluble organic solvent in the aqueous drug can be used alone or in combination of two or more, and the concentration thereof is preferably 30 to 70% by weight, more preferably 30 to 60% by weight, still more preferably 30 to 50%. % By weight. Moreover, when using together with the acid and electrolyte which are mentioned later, Preferably it is 1 to 50 weight%, More preferably, it is 5 to 40 weight%, More preferably, it is the range of 10 to 30 weight%.

  Typical examples of the acid and the electrolyte include those that temporarily insolubilize the water-soluble binder by salting out or crosslinking. The salt used for salting out is not particularly limited as long as it is a water-soluble salt, and various salts can be used. On the other hand, as a salt used for crosslinking, a substance selected depending on the kind of the binder is different. Examples thereof include water-soluble salts that donate potassium ions that crosslink with carrageenan, guar gum, and the like to gel in an aqueous drug. Moreover, the water-soluble salt which donates the bivalent metal ion which bridge | crosslinks and insolubilizes with a carboxylic acid-type binder in presence of a small amount of water-soluble solvent in a chemical | medical solution is mentioned. On the other hand, boric acid salts such as boric acid and sodium tetraborate that crosslink and gel with polyvinyl alcohol can be mentioned. The concentration of these acids and electrolytes in aqueous chemicals varies depending on the type of binder and the content in hydrolyzed paper, so it cannot be specified unconditionally. In consideration, it is in the range of 1 to 10% by weight, preferably 1 to 5% by weight.

  The aqueous drug is formed by blending the above-described crosslinking agent and organic solvent using water as a medium. In addition to these components, surfactants, bactericides, chelating agents, bleaching agents, deodorants, fragrances and the like may be added to the aqueous drug as necessary to enhance the cleaning performance of the aqueous drug. As the surfactant, any of an anionic surfactant, a nonionic surfactant, a cationic surfactant and an amphoteric surfactant can be used. In particular, from the viewpoint of compatibility between cleanability and finish, polyoxyalkylene (Alkylene oxide addition mole number 1-20) alkyl (straight chain or branched chain having 8 to 22 carbon atoms) ether, alkyl (straight chain or branched chain having 8 to 22 carbon atoms) glycoside (average sugar condensation degree 1 to 5) , Nonionic surfactants such as sorbitan fatty acid (straight or branched chain having 8 to 22 carbon atoms) ester and alkyl (straight or branched chain having 6 to 22 carbon atoms) glyceryl ether, and alkylcarboxybetaine and alkylsulfobetaine , Alkylhydroxysulfobetaine, alkylamidocarboxybetaine, alkylamidosulfobetaine, alkylamidohydro 8-24 amphoteric surfactants alkyl carbon atoms such as shea sulfobetaine is preferably used.

  The aqueous drug is preferably impregnated in an amount of 100 to 500% by weight, more preferably 100 to 300% by weight, based on the weight (dry basis) of the hydrolytic paper, from the viewpoint that a sufficient wiping effect is exhibited.

  On the other hand, examples of the water-swellable binder include fibrous polyvinyl alcohol, fibrous carboxymethyl cellulose, and fibrous carboxyethyl cellulose. When such a water-swellable binder is used, paper is generally mixed with raw fiber such as pulp fiber. The content of the water-swellable binder in the fiber sheet is preferably 5 to 40% by weight, more preferably 8 to 8% from the viewpoints of maintaining bulkiness, appropriate wet strength expression, good water disintegration expression, and economic efficiency. It is in the range of 30% by weight, more preferably 10-25% by weight. Even when a water-swellable binder is used, as in the case of the water-soluble binder described above, the swelling of the binder is temporarily suppressed in a state where the water-disintegrating paper is impregnated with an aqueous chemical containing water at a high concentration. It preferably functions as a binder that maintains the bond between the fibers and plays a role in maintaining bulkiness and strength during cleaning. For example, in the case of fibrous polyvinyl alcohol, boric acid salts such as boric acid and sodium tetraborate, and in the case of fibrous carboxymethyl cellulose and fibrous carboxyethyl cellulose, divalent such as magnesium ion, calcium ion, and zinc ion. Water-soluble salts that generate metal ions are preferably used.

  As described above, there are various combinations of the water-soluble or water-swellable binder and the agent that temporarily insolubilizes or suppresses the swelling of the binder matching the binder. Among them, the carboxylic acid-based water-soluble binder and divalent metal ions, A combination of aqueous drugs containing a hydrophilic organic solvent is preferred.

  Among the carboxylic acid-based water-soluble binders, an alkali metal salt of carboxymethyl cellulose (hereinafter also referred to as CMC) is particularly preferable. CMC has a degree of etherification of 0.8 to 1.2, particularly 0.85 to 1.1, and has good performance as a binder, and has good affinity with a crosslinking agent described later. It is preferable from the point. CMC has a viscosity of 10 to 40 mPa · s, particularly 15 to 35 mPa · s at 25 ° C., and a viscosity of 5 to 4% aqueous solution at the same temperature is 2500 to 4000 mPa · s, particularly 2700 to 3800 mPa · s. In addition, when the viscosity of a 5% by weight aqueous solution at 60 ° C. is 1200 mPa · s or less, it is preferable from the viewpoint of handling properties when it is added to paper by spraying or the like.

  In the hydrolytic paper containing a carboxylic acid-based water-soluble binder, the water-based chemical impregnated therein includes a water concentration of 60 to 90% by weight, a water-soluble organic solvent concentration of 8 to 35% by weight, an alkaline earth metal, manganese The composition containing 1 to 5% by weight of a water-soluble divalent metal salt that provides one or more metal ions selected from the group consisting of zinc, cobalt, and nickel temporarily insolubilizes the binder. Therefore, it is preferable from the viewpoint of exhibiting sufficient wet strength and obtaining good water disintegrability.

  The wet strength in the state of being impregnated with an aqueous chemical is 300 cN / 25 mm or more in the machine direction (Machine Direction, abbreviated MD), and 100 cN / 25 mm in the direction perpendicular to the MD (Cross Machine Direction, abbreviated CD). The above is preferable from the viewpoint of robustness during cleaning. About MD direction, More preferably, it is 400 cN / 25mm or more, More preferably, it is 500 cN / 25mm or more. About CD direction, More preferably, it is 150 cN / 25mm or more, More preferably, it is 200 cN / 25mm or more.

  Returning to FIG. 1 again, the convex portion 2 has a substantially hemispherical shape. The same applies to the recess 3. It is preferable that the both sides of the hydrolytic paper 1 of this embodiment have the same performance. From this point of view, it is preferable that the shape and interval of the protrusions 2 on the first surface 1a are substantially the same as that of the second surface 1b. Further, the convex portion 2 existing on the first surface 1a has a front and back relationship with the concave portion 3 existing on the second surface 1b. Similarly, the concave portion 3 existing on the first surface 1a is a convex portion existing on the second surface 1b. It is preferable that it has the relationship between the part 2 and front and back. Furthermore, it is preferable that the shape of the convex part 2 is the reverse of the shape of the concave part 3.

  There is no limitation on the embossed pattern. What is necessary is that the paper after embossing becomes bulky. In particular, uneven steel match embossing tends to be bulky. In this uneven steel match emboss, unevenness is present uniformly and regularly on the roll surface, and the convex part of one roll and the other concave part are engaged between the two rolls. This concavo-convex pattern is a repetition of convex portions and concave portions, and the pitch between the convex portions and the concave portions is preferably 3.5 to 14.0 mm, and more preferably 5.0 to 10.0 mm. Further, the difference (groove depth) between the convex apex and the concave apex is preferably 1 mm to 5 mm, more preferably 1.5 mm to 4.5 mm, and still more preferably 2 mm to 4 mm. From the viewpoint of making it preferable (see FIG. 2).

  Assuming a 10 cm × 10 cm square area on one surface of the hydrolytic paper 1, the convex portion 2 has an average of 50 to 850, particularly 100 to 600, in any position on the surface. Preferably it is formed. By setting the number of the convex portions 2 within this range, the convex portions 2 and the concave portions 3 are arranged in a well-balanced manner. Therefore, when the hydrolytic paper 1 according to the present embodiment is used for cleaning, it is possible to remove dirt. It will be even better.

  As will be apparent from the preferable method for producing hydrolyzed paper, which will be described later, the convex portions 2 and the concave portions 3 in the hydrolytic paper can be freely designed according to the engraving pattern of the embossing roll.

Next, the preferable manufacturing method of the hydrolytic paper 1 is demonstrated. The water disintegrating paper 1 is a substantially water-dispersible fiber sheet containing a water-soluble binder or a water-swellable binder and having a basis weight of 30 to 150 g / m ² , and the moisture content in the fiber sheet is in a dry state. It is obtained by embossing in a state of 10 to 200% by weight with respect to the weight of the fiber sheet, and drying the fiber sheet at the same time or immediately thereafter.

  Water-dispersible fiber sheets containing a water-soluble binder are produced by various methods. For example, it is known that a water-soluble binder and a water-soluble binder fixing agent to pulp fibers are added to a pulp dispersion as a papermaking raw material to produce a hydrolyzed paper stock containing a predetermined amount of the water-soluble binder. (JP-A-3-193996). It is also possible to form a sheet from a pulp dispersion, press dehydrate or semi-dry, and then spray dry or coat dry the water-soluble binder to produce a hydrolyzed paper stock containing a certain amount of water-soluble binder. It is. In this case, a hydrolyzed paper stock having a lower density and better water decomposability can be obtained by using a pre-drying method such as a hot air passage dryer than press dewatering. Furthermore, instead of the above-mentioned wet papermaking method, pulp fibers may be defibrated dry without using water to form a web, and then sprayed or coated with a water-soluble binder, and then dried to produce a fiber sheet. Is possible. This is the so-called airlaid manufacturing method.

  FIG. 3 shows a schematic view of an example of a production apparatus preferably used for producing a water-dispersible fiber sheet containing a water-soluble binder. The manufacturing apparatus (wet paper making machine) shown in FIG. 3 includes a former, a wire part, a first dry part, a spray part, and a second dry part. The former adjusts the furnish supplied from a preparation device (not shown) to a predetermined concentration and supplies it to the wire part. A preparation device (not shown) includes a device that beats and beats raw materials such as pulp fibers, and an addition device that adds additives such as sizing agents, pigments, paper strength enhancers, bleaching agents, and flocculants to the beaten and beaten raw materials. And a stock made of a raw material having a predetermined concentration according to the characteristics of hydrolyzed paper is prepared as a finished stock. It is also possible to mix a binder with the pulp slurry. The wire part is a wet paper that forms the paper stock supplied from the former as a wet paper. The first dry part is for drying the wet paper formed in the wire part. A spray part sprays a binder on the paper dried by the 1st dry part. The second dry part is for drying the paper that has been wetted by spraying the binder in the spray part.

  The paper furnish supplied from the former 4 is made in the wire part, and wet paper is formed on the wire 5. Water is removed from the wet paper by suction by a suction box 6 installed in the wire part, and a predetermined moisture content is obtained. Next, the wet paper is introduced into the first dry part 7 and dried. The first dry part 7 is composed of a through air dryer (hereinafter referred to as TAD). The TAD includes a rotating drum 8 whose peripheral surface is air permeable and a hood 9 that covers the rotating drum 8 almost airtightly. In TAD, air heated to a predetermined temperature is supplied into the hood 9. The heated air flows from the outside of the rotating drum 8 toward the inside. The wet paper web is conveyed in a state of being held on the peripheral surface of the rotating drum 8 rotating in the direction of the arrow in FIG. While being transported in the TAD, the heated paper penetrates the wet paper in the thickness direction, whereby the wet paper is dried to become paper.

  The paper obtained in the first dry part 7 is sprayed with an aqueous solution containing a binder in the spray part. The spray part is a position between the first and second dry parts 7 and 14. Both dry parts 7 and 14 are connected via a conveyor.

  The conveyor includes an upper conveyor belt 10 and a lower conveyor belt 11 that rotate in the directions indicated by the arrows. The conveyor 10 is configured to convey paper to the second dry part 14 while being dried by the TAD of the first dry part 7 and sandwiched between the belts 10 and 11. A vacuum roll 12 is disposed at the folded end on the downstream side of the upper conveyor belt 10. The vacuum roll 12 adsorbs paper on the back surface of the upper conveyor belt 10 and conveys the upper conveyor belt 10 under the adsorbed state.

  As shown in FIG. 3, the spray part includes a spray nozzle 13. The spray nozzle 13 is disposed below the second dry part 14 and so as to face the vacuum roll 12. The spray nozzle 13 sprays a spray liquid containing a binder toward the vacuum roll 12 and adds (externally adds) the spray liquid to paper.

  After the binder is supplied in the spray part, the paper is conveyed to the second dryer part 14. The second dryer part 14 is composed of a Yankee dryer. The paper that has been sprayed with the spray liquid and is in a wet state is conveyed while being held on the peripheral surface of the rotary drum 15 of the Yankee dryer installed in the hood 16. The paper is dried while being held by the rotating drum 15.

  A doctor blade 17 is installed at the exit of the Yankee dryer. The doctor blade 17 peels the paper from the rotary drum 15 of the Yankee dryer while creping the paper. This crepes the paper. Next, the paper is once wound up by a winder (not shown) to form a roll.

  On the other hand, a water-dispersible fiber sheet containing a water-swellable binder can also be produced by various methods. For example, it is known that a predetermined amount of a water-swellable fibrous binder is added to a pulp dispersion, a wet paper is formed, and dried to obtain a fiber sheet (Japanese Patent Application Laid-Open No. 4-370300). (Kaihei 2-74694). It is also possible to produce a fiber sheet by dry-filamentizing the mixed fiber raw material of pulp fiber and water-swellable fibrous binder by the airlaid method instead of the wet papermaking method, forming a web, and then drying. It is.

  Furthermore, it is also possible to produce a fiber sheet containing both a water-soluble binder and a water-swellable binder by combining the above-described methods (hereinafter, the above-described various fiber sheets are also referred to as raw paper).

  The raw paper is dried in the subsequent process, or once stored in the form of a roll and then added with water again, and then subjected to uneven shaping by bulky embossing, or immediately after that, dried. It is formed as a bulky water-disintegrating paper having uneven portions. Such a manufacturing method is performed by, for example, a heat embossing apparatus capable of drying at the same time as bulky uneven shape forming as shown in FIG. The embossing device shown in FIG. 4 has a pair of embossing rolls 18 and 18. Each embossing roll 18 has a large number of irregularities on its peripheral surface and is in mesh with each other. Each embossing roll 18 rotates in the direction indicated by the arrow in FIG. Each embossing roll 18 is made of metal, and a heating means (not shown) is attached so that it can be heated to a predetermined temperature. The embossing roll is preferably made of metal for heating, but as the embossing material, one roll may be made of rubber or paper in addition to the metal. A spray nozzle 19 is installed upstream of the embossing rolls 18 and 18. Water is sprayed from the spray nozzle 19 toward the raw paper.

  As shown in FIG. 4, the raw paper is unwound from a roll (not shown), and after being wetted by the water sprayed from the spray nozzle 19, is sent to the embossing device. In the embossing device, raw paper is pressed between a pair of embossing rolls 18 and 18 and embossed. As described above, the embossing rolls 18 have a structure in which the embossing rolls 18 are engaged with each other, so that the raw paper sandwiched between the two rolls 18 is provided with an uneven shape corresponding to the uneven shape applied to the rolls 18. . That is, the raw paper is steel match embossed. Further, the water contained in the raw paper is dried and removed by the heated embossing roll 18, and a new inter-fiber bond is completed. As a result, a bulky water-disintegrating paper having a number of concavo-convex shapes is obtained.

  FIG. 5 schematically shows the raw paper that has been subjected to steel match embossing. The raw paper in this state is wetted with water. That is, hydrogen bonds between constituent fibers are weakened. For this reason, the constituent fibers 20 of the raw paper are in a state where they can be rearranged by receiving an external force, that is, along the uneven pattern of the steel match emboss. Accordingly, when the raw paper passes between the embossing rolls 18, 18, the fibers are rearranged according to the concave / convex pattern of the embossing roll 18, and the raw paper is shaped unevenly. At the same time, water is dried and removed from the raw paper wet by heating with the embossing roll 18. As a result, in the rearranged fiber structure, hydrogen bonding between the fibers and rebonding between the fibers by the binder are established again. In the bulky water-disintegrating paper obtained in this way, the side wall of the convex part 2 (or the side wall of the concave part 3) is not easily broken. In this way, it is possible to obtain a hydrolytic paper that is excellent in the shape-retaining property of the concavo-convex shape and has little strength reduction. Furthermore, in the hydrolytic paper 1 impregnated with the aqueous agent containing the specific component described above, the binder is temporarily insolubilized or swollen so that the interfiber bonding is maintained and the uneven shape is maintained. And the wet strength is also good.

  Unlike this manufacturing method, when we try to form irregularities by embossing rolls 18 and 18 without wetting paper in a general dry state as it is, it deforms greatly in the vertical direction while maintaining the hydrogen bonds between the constituent fibers. Therefore, as shown in FIG. 6, the bonds between the fibers are broken or the fibers themselves are cut, and the side walls of the convex portions (or the side walls of the concave portions) are broken. As a result, although the uneven portion is once formed on the obtained paper, the uneven portion is easily crushed when an external force is applied. Moreover, the strength of the obtained hydrolyzed paper is greatly reduced as compared with that before the uneven shaping.

  From the viewpoint of successfully forming irregularities on the raw paper, the amount of water sprayed on the paper before being introduced between the embossing rolls 18 and 18 is 10 to 200% by weight based on the dry weight of the raw paper. 10 to 130% by weight, particularly 10 to 50% by weight, especially 10 to 40% by weight is preferable. The raw paper generally contains about 5 to 10% by weight of water in advance, and when the water content in the raw paper is less than 10% by weight, the inter-fiber hydrogen bond is weakened and the binder is swollen. Dissolution cannot be sufficient and sufficient relocation of fibers along the concavo-convex pattern does not occur. On the other hand, if it exceeds 200% by weight, the load for drying becomes large and the economy is inferior. On the other hand, the heating temperature of the embossing rolls 18 and 18 is preferably 150 to 250 ° C. from the viewpoint of sufficiently drying the raw paper. The degree of drying of the raw paper may depend on the conveying speed of the raw paper, but if the conveying speed increases, the raw paper cannot be sufficiently dried only by the heat of the embossing roll. Therefore, by increasing the diameter of the hot embossing roll as shown in FIG. 7, the sheet contact time is lengthened to facilitate drying, and as shown in FIG. 8, a hood 23 covering the embossing rolls 18 and 18 is installed. The air 21 heated to a predetermined temperature is supplied from a part of the hood 23, and the heated air is discharged from the part of the hood as exhaust 22 to increase the drying capacity. It is. In order to easily peel the sheet formed with unevenness by the embossing rolls 18, 18, it is preferable to add a release agent simultaneously with water. Examples of the release agent include higher fatty acid, polyethylene wax, silicone oil, mineral oil, and other solutions containing a surfactant.

  On the other hand, as another method, a sheet containing a fiber that does not contain a water-soluble binder and is substantially water-dispersible is manufactured by a wet papermaking method or an airlaid method, and a water-soluble binder aqueous solution is sprayed in the process. To obtain a sheet containing a water-soluble binder and a wet state containing a predetermined amount of water, then embossing the fiber sheet in this state, and drying at the same time or immediately thereafter, as desired. It is possible to obtain a hydrolytic paper having the following physical properties. In FIG. 9, the short fibers dried from the former 24 are opened in the dry paper making and sucked onto the vacuum conveyor 25 to form a web, sprayed with a water-soluble binder by the spray nozzle 13, and embossed by the embossing device 18. I do. Then, it is dried with an air-through dryer 7. In addition, the code | symbol in FIG. 9 has shown the member similar to the code | symbol in FIG. Moreover, the explanation regarding the manufacturing method described above is appropriately applied to points that are not particularly described regarding the method shown in FIG. 9.

  In addition, after manufacturing a fiber sheet that does not contain a water-soluble binder, an aqueous solution in which the water-soluble binder is dissolved can be sprayed and added in an embossing apparatus as shown in FIG. It is possible to obtain. In that case, the amount of the water-soluble binder contained in the fiber sheet is preferably 1 to 30% by weight, particularly 2 to 15% by weight, from the viewpoint of maintaining bulkiness, developing appropriate wet strength, and economical. . The amount of water added simultaneously with the water-soluble binder is 10 to 200% by weight, particularly 10 to 130% by weight, especially 10 to 50% by weight, and more preferably 10 to 40% by weight, based on the dry weight of the raw paper. It is preferable that

  As described above, in the present production method, by embossing and drying under a predetermined moisture content, it is possible to reduce the occurrence of tearing on the paper, and to form a large number of bulky uneven portions without reducing the strength. Can be formed. In addition, the height of the concavo-convex portion can be made sufficiently high by appropriate selection of the embossing roll. In addition, the formed uneven portion has high shape retention.

  The hydrolyzed paper 1 impregnated with the aqueous drug does not hydrolyze to the extent that it is impregnated with the aqueous drug, but when it is discarded in a large amount of water, it quickly disintegrates at the fiber level. The degree of water disintegration is measured by the ease of loosening as defined in JIS P 4501-1993 (toilet paper), and the lower this value, the better the water disintegration. As a standard of ease of loosening, 100 seconds or shorter is preferable, and 60 seconds or shorter is more preferable.

  The water disintegrating paper 1 impregnated with an aqueous chemical is suitable for use as a cleaning article around the water such as a toilet, a washroom, and a kitchen for an object, and as a sheet for removing a butt, wiping a body for care, and a makeup remover. Used. The cleaning article after use should just be poured into water and discarded, and when drained into water, it will be quickly disintegrated, so the drain pipe will not be clogged.

  The present invention is not limited to the embodiment. For example, the hydrolytic paper is not limited to a single-layer structure, and may have a multilayer structure including a plurality of multi-plies. In the case of a multilayer structure, a water-soluble binder or a water-swellable binder may be contained in at least the surface layer paper.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” and “part” mean “% by weight” and “part by weight”, respectively.

[Examples 1 to 6]
Using the wet paper machine shown in FIG. 3, a wet paper was obtained by making a paper stock of 100% of softwood bleached kraft pulp (NBKP). The wet paper was dried with a through air dryer 7 as a first dryer to a moisture content of 4% by weight. The obtained paper is sandwiched and conveyed between a pair of plastic conveyors 10, 11 and sprayed with a 5% solution at 60 ° C and 1000 mP · s CMC (etherification degree 0.9, made by Nippon Paper Industries) binder liquid. Sprayed with a nozzle 13. The spray amount was 130% with respect to the weight of the paper. The amount of CMC added was 6.5% based on the weight of the paper. The paper to which CMC was added was dried with a Yankee dryer 14 as a second dryer, and then creped with a doctor blade 17. Thus, a CMC-added paper having a basis weight of 30 g / m ² was produced. Further, using the same wet paper machine of FIG. 3, CMC-unadded paper having a basis weight of 30 g / m ² was produced. These two types of paper were laminated in the order of CMC-added paper / CMC non-added paper / CMC-added paper in a separate step to prepare a 3-ply fiber sheet (raw paper) having a basis weight of 90 g / m ² .

  A fiber sheet having a three-ply structure was unwound and water was sprayed using a spray nozzle 19 shown in FIG. The moisture content of the fiber sheet sprayed with water was measured with a heat-drying moisture meter (MX-50 manufactured by A & D). The amount of water sprayed relative to the weight of the dried fiber sheet was as shown in Table 1. The fiber sheet sprayed with water was introduced between the pair of embossing rolls 18 and 18 shown in FIG. Each embossing roll has a large number of irregularities on its peripheral surface and is in mesh with each other. Each embossing roll 18 was heated to the temperature shown in Table 1. The fiber sheet was sandwiched between a pair of embossing rolls 18 and 18 to form irregularities. Further, the water contained in the fiber sheet was removed by the heat of the embossing roll 18. In this way, bulky hydrolytic paper was obtained. Table 1 shows the basis weight of the hydrolyzed paper.

  Next, hydrolyzed paper was impregnated with aqueous drug A having the following formulation. The amount of impregnation was twice the dry weight of the hydrolytic paper before impregnation.

[Comparative Example 1]
The process was the same as in Examples 1 to 6 until a fiber sheet having a basis weight of 90 g / m ² having a three-ply structure of CMC added paper / CMC non-added paper / CMC added paper was produced. When this fiber sheet was embossed in a separate step, embossing was performed between embossing rolls 18 and 18 that were not sprayed with water and were not heated. The step of impregnating aqueous drug A was carried out in the same manner as in Examples 1 to 6 to obtain hydrolyzed paper.

[Examples 7 and 8]
In a wet paper machine, blended paper with 90 parts: 10 parts of bleached softwood bleached kraft pulp (NBKP) and fibrous PVA (Kuraray Klaron KII) and dried with a Yankee dryer to produce a sheet with a basis weight of 33 g / m ² did. In another step, the sheet was made into a two-ply structure to obtain a fiber sheet (raw paper). Thereafter, in the same manner as in Examples 1 to 6, an aqueous chemical was impregnated to obtain hydrolyzed paper. However, an aqueous drug B having the following formulation was used as the aqueous drug.

[Comparative Example 2]
When embossing the fiber sheet in a separate step, embossing was performed between the embossing rolls 18 and 18 that were not sprayed with water and were not heated. Except for these, water-decomposable paper was obtained in the same manner as in Examples 7 and 8.

[Aqueous drug A (when the binder is CMC)]
・ Alkyl glucoside 0.2%
・ CaCl ₂ 3%
・ Propylene glycol monomethyl ether 13%
・ 3-methyl-1,3-butanediol 5%
・ Water balance

[Aqueous drug B (when the binder is PVA))
・ Alkyl glucoside 0.2%
・ Boric acid 3%
・ Propylene glycol monomethyl ether 13%
・ 3-methyl-1,3-butanediol 5%
・ Water balance

[Performance evaluation]
The thickness Td (under a load of 0.3 kPa) of the hydrolytic paper obtained in each example and each comparative example and the thickness Tw (under a load of 2.2 kPa) of the hydrolytic paper impregnated with the aqueous chemical were measured. Based on these values, the thickness ratio Tw / Td was calculated. Further, the strength (breaking strength) of the hydrolytic paper was measured by the following methods. Furthermore, the water disintegration property of the water disintegrating paper was measured by the following method. These results are shown in Table 1.

[Strength (breaking strength)]
Regarding the breaking strength in the MD direction, the sample is cut out 100 mm in the MD direction and 25 mm in the CD direction, and attached to a tensile tester (TENSILON RTA-100 manufactured by ORIENTEC) with a distance between chucks of 50 mm so that the MD direction becomes the tensile direction. The strength when the sample is pulled and broken at a tensile speed of 300 mm / min is defined as the breaking strength. Regarding the breaking strength in the CD direction, the sample is cut 100 mm in the CD direction and 25 mm in the MD direction, and attached to a tensile tester with a distance between chucks of 50 mm so that the CD direction becomes the tensile direction. Thereafter, the measurement is performed in the same manner as the breaking strength in the MD direction.

[Water disintegration]
The water-decomposable cleaning article was cut into a square so that the weight of the paper (not including the aqueous drug) was 0.3 g, and used as a water-decomposability measurement sample. Others were measured based on the ease of loosening of toilet paper (JIS P4501).

  As is apparent from the results shown in Table 1, it can be seen that the hydrolytic paper of each Example has a thickness ratio as large as 0.7 or more and has shape retention with respect to a load. Further, the dry strength and wet strength of the hydrolytic paper of each example are higher than those of the comparative examples. Furthermore, it can be seen from the results of the examples that embossing with a large amount of water spray and a high moisture content tends to improve the shape retention and strength of the thickness.

It is a perspective view which shows one Embodiment of the hydrolytic paper manufactured based on the suitable manufacturing method of this invention. It is a principal part enlarged view of an embossing roll. It is a schematic diagram which shows the paper making apparatus of a hydrolytic paper. It is a schematic diagram which shows an embossing apparatus. It is a schematic diagram which shows the state of uneven | corrugated shaping. It is a schematic diagram which shows the state of uneven | corrugated shaping at the time of drying. It is a schematic diagram which shows an embossing apparatus. It is a schematic diagram which shows an embossing apparatus and a hot air apparatus. It is a schematic diagram which shows the embossing in dry papermaking (airlaid papermaking).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrolytic paper 2 Convex part 3 Concave part 4 Former 5 Wire 6 Suction box 7 Through air dryer (TAD)
8 Rotating drum 9 Hood 10 Upper envelope belt 11 Lower envelope belt 12 Vacuum roll 13 Spray nozzle 14 Yankee dryer 15 Rotating drum 16 Hood 17 Doctor knife 18 (Heat) Embossing roll 19 Spray nozzle 20 Fiber 21 Heated air 22 Exhaust 23 Hood 24 Former 25 Vacuum conveyor 26 Wire

Claims (7)

Embossing with a water sheet containing a water-soluble binder or a water-swellable binder and having a basis weight of 30 to 150 g / m ² and a water content of 10 to 200% by weight. The fiber sheet is dried simultaneously with or immediately after that.   The method for producing hydrolyzed paper according to claim 1, wherein the fiber sheet is impregnated with an aqueous drug after the fiber sheet is dried.   The method for producing hydrolytic paper according to claim 1 or 2, wherein the embossing is performed using a pair of embossing rolls having an uneven portion meshing with each other.   4. The hydrolysis according to any one of claims 1 to 3, wherein a water-soluble binder is contained in an amount of 1 to 30% by weight based on the fiber sheet, or a water-swellable binder is contained in an amount of 5 to 40% by weight based on the fiber sheet. A method for producing sex paper.   The water-soluble binder is a water-soluble binder having a carboxyl group, and the water-swellable binder is a cellulose-based or starch-based derivative having a fibrous carboxyl group, or a polyvinyl alcohol having a hydroxyl group or a derivative thereof. The method for producing hydrolyzed paper according to any one of claims 1 to 4.   The method for producing hydrolytic paper according to any one of claims 2 to 5, wherein the aqueous drug contains an agent capable of insolubilizing a water-soluble binder and a water-swellable binder. A water-soluble binder aqueous solution is added to a sheet containing fibers that do not contain a water-soluble binder and are substantially water-dispersible, so that the water-soluble binder content in the sheet is 1 to 30% by weight and is in a dry state. A fiber sheet having a water content of 10 to 200% by weight with respect to the weight of the sheet is obtained, embossed on the fiber sheet in this state, and simultaneously or immediately after that, the fiber sheet is dried. Production method.