Water-soluble sheet

Abstract

We provide a water-soluble sheet that enables further improvements in environmental considerations. [Solution] The present invention provides a hydrolytic sheet having a base paper sheet 20, wherein the base paper sheet contains bamboo fiber pulp, and the bamboo fiber pulp content is 10% to less than 100% by mass relative to the total mass of the base paper sheet, and a hydrolytic sheet having a base paper sheet, wherein the base paper sheet is composed of bamboo fiber pulp. When the base paper sheet contains bamboo fiber pulp, the base paper sheet may also contain at least one selected from the group consisting of wood pulp, synthetic pulp, recycled paper pulp, synthetic pulp, semi-synthetic fibers (for example, rayon), bleached softwood kraft pulp, bleached hardwood kraft pulp, kenaf, straw, cotton, and silkworm floss. The base paper sheet may be embossed to create a bulky structure by forming numerous bumps 120 on it, thereby increasing its strength and improving its cleaning function (especially its wiping function).

Description

Technical Field

[0001] The present invention relates to a hydrolyzable sheet.

Background Art

[0002] Conventionally, hydrolyzable sheets have been widely used in toilet cleaners. Generally, hydrolyzable sheets used in toilet cleaners are formed by stacking a plurality of tissue papers and adhering them to each other via a water-soluble binder, and subjecting them to embossing to form a bulky structure with a large number of concavo-convex forms, and impregnating them with an aqueous agent. A paper towel for toilet cleaning having such a basic configuration is shown, for example, in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] s The paper towel for toilet cleaning proposed in Patent Document 1 is formed by stacking a plurality of water-soluble papers and adhering between the papers with a water-soluble adhesive, and subjecting the whole to concavo-convex embossing to form a towel body, and impregnating the towel body with a disinfectant solution. However, the paper towel for toilet cleaning proposed in Patent Document 1 may not be able to further improve consideration for the environment.

[0005] Therefore, the present invention has been made in view of such a situation, and a main object thereof is to provide a hydrolyzable sheet capable of further improving consideration for the environment.

Means for Solving the Problems

[0006] The inventor, through diligent research to solve the above-mentioned objectives, has surprisingly succeeded in developing a hydrolytic sheet that can achieve further improvements in environmental considerations, thus completing this invention.

[0007] In other words, the first aspect of the present invention is, Having a base paper sheet, The base paper sheet contains bamboo fiber pulp, The present invention provides a hydrolytic sheet in which the bamboo fiber pulp content is 10% to less than 100% by mass relative to the total mass of the base paper sheet.

[0008] In the first side of the hydrolyzable sheet according to the present invention, The aforementioned base paper sheet It may also include at least one selected from the group consisting of wood pulp, synthetic pulp, recycled paper pulp, synthetic pulp, semi-synthetic fibers, bleached softwood kraft pulp, bleached hardwood kraft pulp, kenaf, straw, cotton, and silkworm cocoons.

[0009] Furthermore, a second aspect of the present invention is, Having a base paper sheet, The present invention provides a water-soluble sheet in which the base paper sheet is composed of bamboo fiber pulp. [Effects of the Invention]

[0010] This invention can achieve further improvements in environmental considerations. The effects described herein are not necessarily limited to those described herein, and any of the effects described herein may also be present. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a process diagram showing an example of manufacturing a water-soluble sheet according to the present invention. [Figure 2] Figure 2 is a partial plan view showing an example of a water-soluble sheet according to the present invention. [Figure 3] Figure 3 is a longitudinal cross-sectional view along line AA in Figure 2. [Modes for carrying out the invention]

[0012] The following describes preferred embodiments for carrying out the present invention. The embodiments described below are examples of typical embodiments of the present invention and should not be interpreted as narrowing the scope of the present invention. Unless otherwise specified, in the drawings, "up" means the upward direction or upper side in the drawing, "down" means the downward direction or lower side in the drawing, "left" means the left direction or left side in the drawing, and "right" means the right direction or right side in the drawing. In the explanation using the drawings, the same or equivalent elements or members are denoted by the same reference numeral, and redundant explanations are omitted unless there are special circumstances.

[0013] <Summary of this invention> First, I will explain the outline of this invention. This invention relates to a water-soluble sheet used in toilet cleaners and the like.

[0014] The first aspect of the hydrolytic sheet according to the present invention is a hydrolytic sheet having a base paper sheet, wherein the base paper sheet contains bamboo fiber pulp, and the bamboo fiber pulp content is 10% to less than 100% by mass relative to the total mass of the base paper sheet. In the first aspect of the hydrolytic sheet according to the present invention, the base paper sheet may contain at least one selected from the group consisting of wood pulp, synthetic pulp, recycled paper pulp, synthetic pulp, semi-synthetic fibers, bleached softwood kraft pulp, bleached hardwood kraft pulp, kenaf, straw, cotton, and silkworm cocoons. The second aspect of the hydrolytic sheet according to the present invention is a hydrolytic sheet having a base paper sheet, wherein the base paper sheet is composed of bamboo fiber pulp. In the second aspect of the hydrolytic sheet according to the present invention, the bamboo fiber pulp content is 100% by mass relative to the total mass of the base paper sheet. The method for manufacturing the first and second side-water-soluble sheets according to the present invention comprises: an embossing step in which a base paper sheet impregnated with a water-soluble binder is used, and the base paper sheet is embossed to form a bulky portion with numerous indentations on the base paper sheet; a water-impregnation step in which water is supplied to the base paper sheet from the outside after the embossing step to impregnate the base paper sheet with water; a drying step in which the base paper sheet is dried after the water-impregnation step; a folding step in which the base paper sheet is folded after the drying step; and an aqueous agent impregnation step in which an aqueous agent is supplied to the base paper sheet to impregnate the base paper sheet with the aqueous agent. The first and second side-water-soluble sheets according to the present invention can achieve further improvements in environmental considerations.

[0015] The above description constitutes an overview of the present invention.

[0016] The following describes preferred embodiments for carrying out the present invention in a specific and detailed manner. It should be noted that the embodiments described below are merely examples of representative embodiments of the present invention, and this should not be interpreted as narrowing the scope of the present invention.

[0017] The hydrolyzable sheet according to the embodiment of the present invention is manufactured by subjecting a base paper sheet as a raw material sheet to processing in a plurality of steps to obtain a hydrolyzable sheet. The base paper sheet contains bamboo fiber pulp. The bamboo fiber pulp is an aggregate of bamboo fibers and may also be referred to as bamboo pulp. The content of the bamboo fiber pulp is 10% by mass to less than 100% by mass with respect to the total mass of the base paper sheet. Preferably, the content of the bamboo fiber pulp is 40% by mass to 60% by mass with respect to the total mass of the base paper sheet. More preferably, the content of the bamboo fiber pulp is 50% by mass with respect to the total mass of the base paper sheet. When the base paper sheet contains bamboo fiber pulp, the base paper sheet may contain at least one selected from the group consisting of wood pulp, synthetic pulp, waste paper pulp, synthetic pulp, semi-synthetic fibers (for example, rayon), softwood kraft pulp, hardwood kraft pulp, kenaf, straw, cotton, and cocoon silk. The base paper sheet may contain a toilet paper material formed by blending softwood kraft pulp and hardwood kraft pulp. Further, the base paper sheet is composed of bamboo fiber pulp. In this case, the content of the bamboo fiber pulp is 100% by mass with respect to the total mass of the base paper sheet. The environmental merits of bamboo fiber pulp are as follows. · Bamboo fiber pulp is a material that contributes to reducing environmental impact. Bamboo fiber pulp (bamboo) grows quickly, regenerates naturally after harvesting, and requires little pesticide, fertilizer, or irrigation, so it is useful as a sustainable resource. · Bamboo fiber pulp is a renewable biomass raw material. · Bamboo fiber pulp has a high CO2 absorption capacity and can absorb about five times as much carbon dioxide as an average hardwood tree. The density of the bamboo fiber pulp is, for example, 0.4 g / cm3 or less, and the pH (10% slurry) is, for example, 6 to 8. The bamboo fiber pulp may be water-soluble or may not be water-soluble.

[0018] The embossing process in the hydrolyzable sheet according to the embodiment of the present invention gives a large number of concavities and convexities to the base paper sheet to form a bulky structure, thereby increasing the strength and enhancing the cleaning function (especially the wiping function).

[0019] As the water-soluble binder used in the hydrolyzable sheet of the embodiment according to the present invention, any material may be used as long as it has a predetermined adhesive force and can impart a predetermined strength to the hydrolyzable sheet, and various materials can be used.

[0020] Examples of the water-soluble binder used in the hydrolyzable sheet of the embodiment according to the present invention include polysaccharide derivatives, natural polysaccharides, synthetic polymers, etc. Examples of polysaccharide derivatives include carboxymethyl cellulose, carboxyethyl cellulose, carboxymethylated starch or its salt, starch, methyl cellulose, ethyl cellulose, etc. Examples of natural polysaccharides include guar gum, tragacanth gum, xanthan gum, sodium alginate, carrageenan, gum arabic, gelatin, casein, etc. Examples of synthetic polymers include polyvinyl alcohol, polyvinyl alcohol derivatives, salts of polymers or copolymers of unsaturated carboxylic acids, etc., and examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic anhydride, maleic acid, fumaric acid, etc. Among the above, it is particularly preferable to use carboxymethyl cellulose.

[0021] The base paper sheet impregnated with the water-soluble binder is further impregnated with an aqueous agent. The aqueous agent contains an agent that imparts a cleaning function to the hydrolyzable sheet of the embodiment according to the present invention, and also contains agents formulated for other purposes. As the aqueous agent, those having an aqueous composition prepared by blending water, a crosslinking agent, and a water-soluble organic solvent are used, and surfactants, bactericides, preservatives, deodorants, bleaching agents, chelating agents, fragrances, etc. can be blended as necessary.

[0022] A crosslinking agent reacts with a water-soluble binder to form a crosslinked structure, thereby improving its physical strength. When a water-soluble binder containing carboxyl groups, such as carboxymethylcellulose, is used as the water-soluble binder, it is preferable to use a polyvalent metal ion as the crosslinking agent. Examples of such polyvalent metal ions include zinc, alkaline earth metals, manganese, nickel, and cobalt. Specifically, zinc, calcium, barium, cobalt, and nickel ions are preferably used, as they are preferable for providing sufficient wet strength.

[0023] The polyvalent metal ions mentioned above are used in the form of water-soluble metal salts such as sulfates, chlorides, hydroxides, carbonates, and nitrates. Crosslinking agents are one of the components that make up aqueous agents, but as will be described later, they may also be used separately from the aqueous agents.

[0024] As water-soluble organic solvents, monohydric alcohols such as ethanol, methanol, and isopropyl alcohol; glycols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, and hexylene glycol; monoethers or diethers of these glycols with lower alcohols such as methanol, ethanol, propanol, and butanol; esters of the aforementioned glycols with lower fatty acids; and polyhydric alcohols such as glycerin and sorbitol can be used.

[0025] Examples of surfactants that may be added to aqueous agents as needed include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. In particular, it is preferable to use nonionic surfactants such as polyoxyalkylene alkyl ethers, alkyl glycosides, and sorbitan fatty acid esters.

[0026] Next, a method for manufacturing a water-soluble sheet according to an embodiment of the present invention will be described based on the process diagram shown in Figure 1. In the same figure, reference numeral 100 denotes a feed roll around which a long base paper sheet 20 impregnated with a water-soluble binder is wound, and the base paper sheet 20 is fed in the direction of arrow Y by a pinch roll 300. The base paper sheet 20 may be a single-layer structure consisting of one sheet of thin paper such as toilet paper, or a multi-layer structure made by stacking two or more sheets of thin paper. As described above, the base paper sheet 20 is impregnated with a water-soluble binder, and the method for manufacturing the base paper sheet 20 will be described below. In this specification, the base paper sheet before impregnation with the water-soluble binder is referred to as the pre-impregnation base paper sheet, and the base paper sheet after impregnation with the water-soluble binder is referred to as the base paper sheet 20.

[0027] The base paper sheet 20 is impregnated with a water-soluble binder. For example, carboxymethylcellulose is used as the water-soluble binder. The water-soluble binder is supplied by spraying the water-soluble binder solution onto the surface of the base paper sheet before impregnation from the nozzle of a spraying device. In this way, the water-soluble binder is supplied to the base paper sheet before impregnation from the outer side of the sheet and impregnated. In this case, the water-soluble binder solution may be sprayed only on one side of the base paper sheet before impregnation, or on both sides. As the spraying nozzle used for spraying, either a one-fluid nozzle that sprays pressurized water-soluble binder solution alone, or a two-fluid nozzle that mixes compressed air and water-soluble binder solution and sprays the water-soluble binder solution in a mist using the pressure of the compressed air, can be used.

[0028] The means of supplying the water-soluble binder solution are not limited to the spraying described above. For example, methods such as dropping the water-soluble binder solution onto the surface of the base paper sheet before impregnation, or coating the sheet, may be employed. Furthermore, the method for manufacturing a water-soluble sheet according to the embodiment of the present invention may include a step of impregnating the base paper sheet 20 having a bulky portion 170 with an aqueous agent and a step of impregnating the base paper sheet 20 with a crosslinking agent, which is a component of the aqueous agent, as will be described later. In the aqueous agent impregnation step, the aqueous agent solution is supplied to the base paper sheet 20, and in the crosslinking agent impregnation step, the crosslinking agent solution is supplied to the base paper sheet 20. Here, as with the means of supplying the water-soluble binder solution, any means such as spraying, dropping, or coating can be employed, similar to the means of supplying the water-soluble binder solution described above. In the following description, the spraying method will be used as an example of these supply means.

[0029] The amount of water-soluble binder supplied (added) to the unimpregnated base paper sheet is preferably 50% to 100% by weight relative to the weight of the unimpregnated base paper sheet, and the concentration of the water-soluble binder solution is preferably 1% to 20%.

[0030] Since the water-soluble binder solution is supplied from the outer side of the unimpregnated base paper sheet, the surface of the unimpregnated base paper sheet is also impregnated with the water-soluble binder. Consequently, in the water-soluble sheet of the embodiment of the present invention that is finally manufactured, the surface of the water-soluble sheet of the embodiment of the present invention is impregnated with the water-soluble binder solution. The water-soluble binder solution may be impregnated from one side (supply side) of the unimpregnated base paper sheet to the opposite side in the thickness direction (i.e., throughout the entire thickness), or it may be impregnated only partway (i.e., partway through the thickness) without reaching the opposite side. In the former case, where the impregnation is throughout the entire thickness, the surface of one side and the opposite side in the thickness direction of the water-soluble sheet of the embodiment of the present invention will be impregnated with the water-soluble binder.

[0031] In supplying and impregnating with the water-soluble binder described above, a crosslinking agent, which is a component of an aqueous chemical, may also be supplied and impregnated in addition to the water-soluble binder. That is, in the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, the water-soluble binder impregnation step may include a step of impregnating both the water-soluble binder and the crosslinking agent. In the first embodiment of this embodiment, first, a water-soluble binder solution is sprayed onto the base paper sheet before impregnation from the outer side of the base paper sheet to impregnate it with the water-soluble binder, and then a crosslinking agent solution is sprayed to impregnate the base paper sheet 20 with the crosslinking agent. In the second embodiment, first, a crosslinking agent solution is sprayed onto the base paper sheet before impregnation from the outer side of the base paper sheet before impregnation to impregnate it with the crosslinking agent, and then a water-soluble binder solution is sprayed to impregnate the base paper sheet before impregnation with the water-soluble binder. In a third embodiment, a water-soluble binder solution is sprayed onto the unimpregnated base paper sheet from its outer surface, and at the same time, a crosslinking agent solution is sprayed onto it, thereby impregnating it with both the water-soluble binder and the crosslinking agent simultaneously. In each of these embodiments, the entire amount of crosslinking agent necessary for the crosslinking reaction with the water-soluble binder may be impregnated, or only a portion of it may be impregnated.

[0032] As described above, if the water-soluble binder and the crosslinking agent are impregnated together in the water-soluble binder impregnation process, the crosslinking reaction with the water-soluble binder occurs early, and the base paper sheet 20 can be quickly given the required strength.

[0033] The base paper sheet 20 impregnated with a water-soluble binder is sent to a dryer where drying takes place (first drying step). Drying methods include electromagnetic wave drying, aeration drying (hot air drying), infrared drying, and hot roll drying, but electromagnetic wave drying is preferred. Electromagnetic wave drying uses electromagnetic waves to perform drying, and an electromagnetic wave dryer with a mechanism and structure similar to that of a microwave oven can be used for this purpose. In the manufacturing method of a water-soluble sheet according to the embodiment of the present invention, electromagnetic wave drying is performed by microwave heating, and is based on the principle that when microwaves are irradiated, oscillators that connect polar water molecules absorb the microwaves, vibrate and rotate, and the temperature rises, and this temperature rise evaporates the water and dries the sheet.

[0034] Electromagnetic wave drying has the advantage of being able to dry in a short time, and because electromagnetic waves have high penetration ability, they can penetrate into the interior of the base paper sheet 20 and heat it uniformly, thus enabling uniform drying. Furthermore, in electromagnetic wave drying, electromagnetic wave energy is directly applied and there is no secondary energy consumption, so energy can be saved by at least 30% compared to infrared heating, and energy consumption can be reduced, thus contributing to a reduction in manufacturing costs. As an electromagnetic wave dryer used in the manufacturing method of the hydrolyzable sheet according to the embodiment of the present invention, for example, one that has the capacity to dry 1 kg of water in 1 hour per 1 kW of power is preferable. In addition, as an electromagnetic wave dryer installed in a continuous manufacturing facility, it is preferable to use a tunnel-type electromagnetic wave dryer that can continuously pass the base paper sheet 20 inside the dryer, as this is suitable for continuous production.

[0035] In the first drying step, infrared drying can also be suitably used as a means of drying the base paper sheet 20 impregnated with a water-soluble binder. Infrared radiation is an electromagnetic wave with a wavelength range of 0.75 μm to 1000 μm, which is shorter than microwaves. Infrared radiation is divided into near-infrared radiation (wavelength 0.7 μm to 2.5 μm) and far-infrared radiation (wavelength 4 μm to 1000 μm) depending on the wavelength. Near-infrared radiation is not easily absorbed by objects and has low heating efficiency. Therefore, in the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, it is preferable to use far-infrared radiation, which is easily absorbed by objects and has high heating efficiency. In the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, it is preferable to use far-infrared radiation with a wavelength of 4 μm to 50 μm within the far-infrared wavelength range of 4 μm to 1000 μm. Far-infrared radiation with a wavelength of 4 μm to 50 μm has high absorbance with respect to water, and in the case of an object containing a lot of moisture, much of the far-infrared radiation is absorbed in the relatively shallow part from the surface to the interior.

[0036] Far-infrared drying is a method that dries materials by directly transferring heat to them using far-infrared rays, rather than by heating the air. It is a form of drying using radiant heat. Therefore, the materials can be heated efficiently, resulting in shorter drying times. Furthermore, it is possible to reflect the heat rays in a specific direction using reflectors and concentrate them at a predetermined location for heating and drying. By adopting such a drying method, energy efficiency for drying can be improved, and drying process costs can be reduced.

[0037] Any structure of far-infrared dryer equipped with a heating element that generates far-infrared rays can be used, but it is preferable that the heating element's temperature be maintained at 200°C or higher. By maintaining the heating element's temperature at 200°C or higher, far-infrared rays can be generated efficiently. Furthermore, by intermittently supplying power using a thermostat or the like, energy-saving operation becomes possible.

[0038] When drying the base paper sheet 20 impregnated with a water-soluble binder using a dryer, the method for manufacturing a water-soluble sheet according to the embodiment of the present invention is not limited to drying with a single dryer, but may also be configured to install multiple dryers and sequentially send the base paper sheet 20 to each dryer for drying. That is, for example, the base paper sheet 20 transported by a belt conveyor may be sent to a first dryer for drying, and then sent to a second dryer for a second drying. In this case, the degree of drying may be different between the first and second drying stages. Such multi-stage drying is particularly beneficial for electromagnetic wave drying and infrared drying. In the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, electromagnetic wave drying and infrared drying can also be combined. An electromagnetic wave dryer and an infrared dryer may be installed separately. For example, the base paper sheet 20 may be first sent to the electromagnetic wave dryer for electromagnetic wave drying, and then sent to the infrared dryer for infrared drying. Alternatively, the order may be reversed, with infrared drying performed first, followed by electromagnetic wave drying. Furthermore, the first stage of electromagnetic wave drying (or infrared drying) and the second stage of infrared drying (or electromagnetic wave drying) may be repeated alternately several times. In addition, an electromagnetic wave heating mechanism and an infrared heating mechanism may be provided in a single dryer. The base paper sheet 20 may be sent to such a dryer, where heating by electromagnetic waves and infrared rays are applied simultaneously, thereby performing both electromagnetic wave drying and infrared drying at the same time.

[0039] The base paper sheet 20, dried in a dryer, is passed through a pair of upper and lower embossing rolls 400, 400, where it is embossed. The embossing rolls 400, 400 have numerous protrusions for embossing on their circumferential surfaces, and conventionally known embossing rolls can be used. The embossed surface may be formed on only one side of the base paper sheet 20 or on both sides. When embossing is applied to both sides of the base paper sheet 20, an embossing roll consisting of a pair of upper and lower metal rolls, each having numerous protrusions for embossing on its circumferential surface, is used. When embossing is applied to only one side of the base paper sheet 20, an embossing roll consisting of a metal roll with numerous protrusions for embossing on its circumferential surface and a pair of rubber retaining rolls, one above the other, is used.

[0040] As described above, in the method for manufacturing a hydrolyzable sheet according to the embodiment of the present invention, the base paper sheet 20, which has been dried in a dryer, is subjected to embossing. Therefore, there is no risk of the base paper sheet 20 adhering to the embossing rolls 400, 400, and for this reason, it is not necessary to apply a release agent to the embossing rolls 400, 400, nor is it necessary to apply a release agent to the base paper sheet 20. However, in order to more reliably prevent the base paper sheet 20 from adhering to the embossing rolls 400, 400, a release agent may be applied to the embossing rolls 400, 400, or a release agent may be applied to the base paper sheet 20. Embossing can be performed without heating the embossing rolls 400, 400, or it may be performed with the embossing rolls 400, 400 heated to a predetermined temperature. In the latter case, the heating temperature of the embossing rolls 400, 400 is preferably 60°C to 150°C.

[0041] As shown in Figures 2 and 3, embossing creates a textured surface 120 on the base paper sheet 20, consisting of numerous protrusions 130 and recesses 140, and these numerous textured surfaces 120 form a bulky portion 170. Depending on the embossing depth, the processing load may not be able to keep up, and some of the interfiber bonds may break. Such interfiber bond breakage does not occur when the embossing depth is small, but it does occur when the embossing depth is large. For example, when the embossing depth is 1 mm to 5 mm, interfiber bond breakage is likely to occur. In the manufacturing method of the hydrolyzable sheet according to the embodiment of the present invention, the occurrence of interfiber bond breakage may actually be desirable.

[0042] In the next step, water is supplied to the base paper sheet 20, which has a bulky portion 170 formed by numerous bumps 120 (water impregnation step). The water is supplied by spraying water 510 onto the surface of the base paper sheet 20 from the nozzle of a spraying device. In this way, the base paper sheet 20 is supplied with water from the outer side and impregnated. The water 510 may contain any material (for example, a water-soluble binder solution, an aqueous agent, a crosslinking agent, etc.). The water 510 may be sprayed on only one side of the base paper sheet 20 or on both sides. As the spraying nozzle used for spraying, either a one-fluid nozzle that sprays pressurized water 510 alone, or a two-fluid nozzle that mixes compressed air and water 510 and sprays the water 510 in a mist using the pressure of the compressed air, can be used.

[0043] The means of supplying water 510 is not limited to the spraying described above, but for example, a method of dropping water 510 onto the surface of the base paper sheet 20 or a coating method may be employed. Furthermore, the method for manufacturing a water-soluble sheet according to the embodiment of the present invention may include a step of impregnating the base paper sheet 20 having a bulky portion 170 with an aqueous agent and a step of impregnating the base paper sheet 20 with a crosslinking agent, which is a component of the aqueous agent, as will be described later. In the aqueous agent impregnation step, an aqueous agent solution is supplied to the base paper sheet 20, and in the crosslinking agent impregnation step, a crosslinking agent solution is supplied to the base paper sheet 20. Here, as the means of supplying these aqueous agent solution and crosslinking agent solution, any means such as spraying, dropping, or coating can be employed, similar to the means of supplying water described above. In the following description, the spraying method will be used as an example of these supply means.

[0044] The supply of water 510 as described above impregnates the base paper sheet 20 with water 510. Herein, the method for manufacturing a water-soluble sheet according to the embodiment of the present invention includes a mode in which, during embossing, some of the interfiber bonds in the base paper sheet 20 are destroyed, and a mode in which some of the water-soluble binder (for example, a water-soluble binder laminated on the base paper sheet 20 as a film) is destroyed by the dissolution of the water-soluble binder. When such destruction of interfiber bonds or destruction of the water-soluble binder occurs in the base paper sheet 20, the locations of the destroyed interfiber bonds or water-soluble binder become areas where water 510 can easily penetrate, thereby increasing the overall penetration rate of water 510. Consequently, the penetration rate of water 510 is greater than when no destruction of interfiber bonds or water-soluble binder occurs, allowing water 510 to penetrate efficiently. Furthermore, as water 510 enters the areas where interfiber bonds are broken or where the water-soluble binder is broken, the fibers become bonded to each other via the dissolved water-soluble binder, resulting in stronger interfiber bonds. In other words, when the water-soluble binder dries and forms a film, the strength of this binder film is greater than the strength of the fibers themselves, and therefore the strength of the water-soluble sheet according to the embodiment of the present invention can be improved. Moreover, when crosslinking occurs, the strength of the binder film increases even further.

[0045] Since water 510 is supplied from the outer side of the base paper sheet 20, the surface of the base paper sheet 20 is also impregnated with water 510. The water 510 may impregnate the base paper sheet 20 from one side (the supply side) to the opposite side in the thickness direction (i.e., throughout the entire thickness), or it may impregnate only partway through the thickness direction without reaching the opposite side. In the former case, where the water impregnates throughout the entire thickness direction, the water-soluble binder is impregnated on both the one side and the opposite side in the thickness direction of the water-soluble sheet according to the embodiment of the present invention.

[0046] In the process of supplying and impregnating with the water 510 described above, a crosslinking agent, which is a component of an aqueous chemical agent, may also be supplied and impregnated in addition to the water 510. That is, in the method for manufacturing a hydrolyzable sheet according to the embodiment of the present invention, the water impregnation step may include a step of impregnating with both water 510 and a crosslinking agent. In the first embodiment of this embodiment, first, water 510 is sprayed onto the base paper sheet 20 having a bulky portion 170 from the outer surface side of the base paper sheet 2 to impregnate it with water 510, and then a crosslinking agent solution is sprayed to impregnate the base paper sheet 20 with the crosslinking agent. In the second embodiment, first, a crosslinking agent solution is sprayed onto the base paper sheet 20 from the outer surface side of the base paper sheet 20 to impregnate it with the crosslinking agent, and then water 510 is sprayed to impregnate the base paper sheet 20 with water 510. In the third embodiment, water 510 is sprayed onto the base paper sheet 20 from its outer surface, and at the same time, a crosslinking agent solution is sprayed onto it, so that the water 510 and the crosslinking agent are impregnated simultaneously. In each of these embodiments, the entire amount of the crosslinking agent necessary for the crosslinking reaction to form with the water-soluble binder dissolved in water 510 may be impregnated, or only a portion of it may be impregnated.

[0047] The base paper sheet 20 impregnated with water 510 is sent to a dryer 610 where drying takes place. Drying methods include electromagnetic wave drying, aeration drying (hot air drying), infrared drying, and hot roll drying, but electromagnetic wave drying is preferred. Electromagnetic wave drying uses electromagnetic waves to perform drying, and an electromagnetic wave dryer with a mechanism and structure similar to that of a microwave oven can be used for this purpose. In the manufacturing method of a hydrolyzable sheet according to the embodiment of the present invention, electromagnetic wave drying is performed by microwave heating, and is based on the principle that when microwaves are irradiated, oscillators that connect polar water molecules absorb the microwaves, vibrate and rotate, and the temperature rises, and this temperature rise evaporates the water and dries the material.

[0048] Electromagnetic wave drying has the advantage of being able to dry in a short time, and because electromagnetic waves have high penetration ability, they can penetrate into the interior of the base paper sheet 20 and heat it uniformly, thus enabling uniform drying. Furthermore, in electromagnetic wave drying, electromagnetic wave energy is directly applied and there is no secondary energy consumption, so energy can be saved by at least 30% compared to infrared heating, and energy consumption can be reduced, thus contributing to a reduction in manufacturing costs. As an electromagnetic wave dryer used in the manufacturing method of the hydrolyzable sheet according to the embodiment of the present invention, for example, one that has the capacity to dry 1 kg of water in 1 hour per 1 kW of power is preferable. In addition, as an electromagnetic wave dryer installed in a continuous manufacturing facility, it is preferable to use a tunnel-type electromagnetic wave dryer that can continuously pass the base paper sheet 20 inside the dryer, as this is suitable for continuous production.

[0049] Unlike aeration drying (hot air drying), electromagnetic wave drying eliminates the risk of the embossed surface of the surface 120 being crushed by air pressure, and unlike hot roll drying, eliminates the risk of the surface being crushed by mechanical pressure.

[0050] Furthermore, electromagnetic wave drying offers superior drying efficiency compared to aeration drying, infrared drying, and hot roll drying, and can dry in a short time, thus eliminating the risk of embossing reversal, which reduces the height difference of the embossing. Preventing this embossing reversal is of great importance in the manufacturing method of a water-soluble sheet according to the embodiment of the present invention. Specifically, in the manufacturing method of a water-soluble sheet according to the embodiment of the present invention, a water-soluble binder is supplied to the base paper sheet 20 after embossing to impregnate it. As a result, the impregnation with the water-soluble binder removes the distortion caused by embossing, leading to the problem of so-called embossing reversal, where the uneven shape of the uneven body 120 collapses. To solve this problem, the selection of a drying method is crucial. By adopting electromagnetic wave drying as the drying method, the drying time can be significantly reduced compared to other drying methods, allowing for the rapid removal of moisture that causes the embossing reversal. Consequently, the collapse of the uneven shape due to the release of distortion is suppressed, the shape of the uneven form can be maintained, and the embossing reversal can be suppressed. As mentioned above, in electromagnetic wave drying, the electromagnetic waves penetrate to the interior of the base paper sheet 20 and heat it, so the base paper sheet 20 is heated and dried uniformly and quickly, not only on the surface but also inside. This has a significant effect on suppressing the embossing return mentioned above.

[0051] Infrared drying can also be suitably used as a means of drying the base paper sheet 20 impregnated with a water-soluble binder and water 510. Infrared radiation is an electromagnetic wave with a wavelength band of 0.75 μm to 1000 μm, which is shorter than microwaves. Infrared radiation is divided into near-infrared radiation (wavelength 0.7 μm to 2.5 μm) and far-infrared radiation (wavelength 4 μm to 1000 μm) depending on the wavelength. Near-infrared radiation is not easily absorbed by objects and has low heating efficiency. Therefore, in the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, it is preferable to use far-infrared radiation, which is easily absorbed by objects and has high heating efficiency. In the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, it is preferable to use far-infrared radiation with a wavelength of 4 μm to 50 μm within the far-infrared wavelength band of 4 μm to 1000 μm. Far-infrared radiation with a wavelength of 4 μm to 50 μm has high absorbance with respect to water, and in the case of an object containing a lot of moisture, much of the far-infrared radiation is absorbed in the relatively shallow part from the surface to the interior. Therefore, when far-infrared drying is applied to the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, it has the effect of preventing deformation of the embossing. That is, when far-infrared rays are emitted onto the base paper sheet 20 impregnated with a water-soluble binder, the far-infrared rays are absorbed in large quantities in the relatively shallow internal region from the surface of the base paper sheet 20, thereby rapidly heating and drying the area near the surface. As a result, the drying of the embossed surface proceeds in a short time, and as a result, deformation of the embossing due to moisture absorption can be prevented. Furthermore, by preventing deformation of the embossing, it is also possible to prevent embossing return, which is a decrease in the height difference of the embossing. Thus, since the embossed surface can be dried quickly by far-infrared drying, embossing return can be reliably prevented, and therefore, there is an advantage in shortening the time required for the drying process.

[0052] Far-infrared drying is a method that dries materials by directly transferring heat to them using far-infrared rays, rather than by heating the air. It is a form of drying using radiant heat. Therefore, the materials can be heated efficiently, resulting in shorter drying times. Furthermore, it is possible to reflect the heat rays in a specific direction using reflectors and concentrate them at a predetermined location for heating and drying. By adopting such a drying method, energy efficiency for drying can be improved, and drying process costs can be reduced.

[0053] Any structure of far-infrared dryer equipped with a heating element that generates far-infrared rays can be used, but in this case, it is preferable that the heating element's temperature be maintained at 200°C or higher. By maintaining the heating element's temperature at 200°C or higher, far-infrared rays can be generated efficiently. Furthermore, by intermittently supplying power using a thermostat or the like, energy-saving operation is possible. In far-infrared drying, there is no load due to air pressure as in ventilated drying (hot air drying), and there is no load due to mechanical pressure as in hot roll drying, so there is no risk of crushing of the embossed surface or distortion of the base paper sheet 20.

[0054] When drying the base paper sheet 20 impregnated with a water-soluble binder and water 510 using a dryer 610, the method for manufacturing a water-soluble sheet according to the embodiment of the present invention is not limited to drying with a single dryer, but may also be configured to install multiple dryers and sequentially send the base paper sheet 20 to each dryer for drying. That is, for example, the base paper sheet 20 transported by a belt conveyor may be sent to a first dryer for drying, and then sent to a second dryer for a second drying. In this case, the degree of drying may be different between the first and second drying stages. Such multi-stage drying is particularly beneficial in electromagnetic wave drying and infrared drying. In the method for manufacturing a water-soluble sheet according to the embodiment of the present invention, electromagnetic wave drying and infrared drying can also be combined. That is, an electromagnetic wave dryer and an infrared dryer may be installed, and for example, the base paper sheet 20 may first be sent to the electromagnetic wave dryer for electromagnetic wave drying, and then sent to the infrared dryer for infrared drying, or the order may be reversed, with infrared drying performed first and then electromagnetic wave drying. Furthermore, the first stage of drying, electromagnetic wave drying (or infrared drying), and the second stage of drying, infrared drying (or electromagnetic wave drying), may be repeated alternately several times. Alternatively, an electromagnetic wave heating mechanism and an infrared heating mechanism may be provided in a single dryer, and the base paper sheet 20 may be sent to a dryer with such a structure, where heating by electromagnetic waves and infrared heating are applied simultaneously, so that drying by electromagnetic waves and infrared rays are performed at the same time.

[0055] The base paper sheets 20, dried by the dryer 610, are sequentially sent to the folding process, the cutting process, and the aqueous chemical impregnation process.

[0056] Herein, as an alternative method for manufacturing the water-soluble sheet according to the embodiment of the present invention, a base paper sheet 20 having a bulky portion 170 may be impregnated with a water-soluble binder and water 510, and then the base paper sheet 20 impregnated with the water-soluble binder and water 510 may be dried in a dryer 610 as described above (electromagnetic wave drying, far-infrared drying, etc.), and then the dried base paper sheet 20 may be impregnated with a crosslinking agent, and the base paper sheet 20 impregnated with the crosslinking agent may be passed through another dryer for weak drying, and then sent to the folding process. If the base paper sheet 2 is folded in a state where it is completely dried in the dryer 610, there is a risk of cracking occurring at the folds, but according to this embodiment, the drying performed immediately before the folding process is not complete drying but weak drying (for example, semi-drying), so there is no risk of cracking occurring at the folds when folding.

[0057] In the manufacturing method of the hydrolyzable sheet according to the embodiment of the present invention, the above-mentioned cracking problem does not occur if the degree of drying by the dryer 610 is adjusted, and there is no problem in folding the base paper sheet 20 after drying it with the dryer 610. As described above, the dried base paper sheet 20 is sequentially sent to the folding process, the cutting process, and the aqueous agent impregnation process. In the aqueous agent impregnation process, a compositional solution containing water, a crosslinking agent, a water-soluble organic solvent, a surfactant, etc., is supplied to the folded body of the base paper sheet 20 to impregnate it. However, as an alternative manufacturing method of the hydrolyzable sheet according to the embodiment of the present invention, the crosslinking agent, which is a component of the aqueous agent, may be separated from the other components of the aqueous agent, and only the crosslinking agent may be supplied to the base paper sheet 20 at a stage before the folding process to impregnate it. This embodiment will be described below.

[0058] A crosslinking agent solution is sprayed onto the base paper sheet 20 after the drying process is complete. For example, an aqueous zinc sulfate solution is used as the crosslinking agent solution.

[0059] The amount of crosslinking agent solution supplied (added) to the base paper sheet 20 is the amount necessary for metal ions (e.g., zinc ions) to undergo a sufficient crosslinking reaction with the carboxyl groups in the water-soluble binder impregnated in the base paper sheet 20. In the method for producing a hydrolyzable sheet according to the embodiment of the present invention, it is preferable to add at least 1 / 3 mole of the carboxyl groups, and more preferably at least 1 / 2 mole.

[0060] By spraying the base paper sheet 20 with a crosslinking agent solution, the base paper sheet 20 is impregnated with the crosslinking agent, and a crosslinking reaction occurs between the crosslinking agent and the water-soluble binder in the base paper sheet 20. As a result, the water-soluble binder becomes a crosslinked structure, which improves the strength of the base paper sheet 20.

[0061] After the crosslinking agent impregnation process is complete, the base paper sheet 20 is guided to the folding machine 800 and folded a predetermined number of times. For example, it is folded in half from the center, perforations are made at predetermined intervals, this folded body is folded in half again along the perforations to form a four-fold body, and this four-fold body is folded in half again from the center to form an eight-fold body. Alternatively, the base paper sheet 20 may be folded alternately and continuously along the longitudinal direction so that fold lines are formed continuously, and perforations are made at predetermined intervals.

[0062] After the folding process, the base paper sheet 20 is cut to a predetermined size to obtain a folded body 900. Next, an aqueous chemical solution 1000 that does not contain a crosslinking agent is sprayed onto the folded body 900, and the folded body 900 is impregnated with the aqueous chemical that does not contain a crosslinking agent (hereinafter, the aqueous chemical that does not contain a crosslinking agent is referred to as the crosslinking agent-free chemical). The crosslinking agent-free chemical used is a mixture of water, a water-soluble organic solvent, a surfactant, a disinfectant, a preservative, a deodorant, a fragrance, etc.

[0063] For sufficient cleaning function, it is preferable to supply the crosslinking agent-free agent so that it impregnates the base paper sheet 20 in the folded body 900 at an amount of 50% to 200% by weight, preferably 130% to 150% by weight.

[0064] In this way, a water-soluble sheet according to the embodiment of the present invention, which is impregnated with an aqueous agent, is obtained. The water-soluble sheet according to the embodiment of the present invention, manufactured by the manufacturing method of the water-soluble sheet according to the embodiment of the present invention, is a concept that means not only a folded shape (folded body) but also a flat sheet in an unfolded state. Multiple bundles of the folded water-soluble sheets are packed into a sealed bag, thus obtaining a product 1100 that can be used as a toilet cleaner or baby wipe.

[0065] In the above embodiment, the method is not limited to impregnating the folded body 900 with a crosslinking agent that does not contain water at the stage before bagging, but also includes storing the folded body 900 in a sealed bag, and in this stored state The crosslinking agent-free chemical solution may be sprayed and supplied through the opening of the bag entrance to impregnate the folded body 900 with the crosslinking agent-free chemical.

[0066] In the above-described embodiment, the process of impregnating the base paper sheet with an aqueous agent is divided into two steps: impregnating the base paper sheet with a crosslinking agent, which is a component of the aqueous agent, and impregnating the base paper sheet with an aqueous agent that does not contain a crosslinking agent. However, as an alternative method for manufacturing the hydrolyzable sheet according to the embodiment of the present invention, the crosslinking agent impregnation may be omitted before the folding process and performed after the folding process. In this case, an aqueous agent solution containing a crosslinking agent is sprayed onto the folded body 900 to impregnate the folded body 900 with the aqueous agent containing a crosslinking agent.

[0067] In an embodiment in which the folded body 900 is impregnated with an aqueous agent containing this crosslinking agent, it is preferable that the amount of crosslinking agent supplied to the folded body 900 and the amount of aqueous agent components other than the crosslinking agent component supplied are the same as in the above embodiment (impregnation of the crosslinking agent before the folding process and impregnation of the crosslinking agent-free agent after the folding process).

[0068] In the method for manufacturing a hydrolyzable sheet according to the embodiment of the present invention, among the two other manufacturing methods described above, the embodiment in which the crosslinking agent is impregnated into the base paper sheet 20 at a stage before the folding process is preferred. The reason for this is as follows.

[0069] In other words, in an embodiment in which the folded body 900 is impregnated with an aqueous agent containing a crosslinking agent after the folding process, multiple folded bodies 900 are arranged in an upright position, and the aqueous agent solution is sprayed and supplied from above in this state. As a result, the aqueous agent supplied by spraying is impregnated from the periphery of the folded body 900, and the impregnation distribution gradually spreads toward the center. Because of this difference in the progress of impregnation, the crosslinking reaction occurs first from the periphery, and the crosslinking agent, which is a component of the aqueous agent, is preferentially consumed in the crosslinking reaction in the periphery. As a result, the concentration of the crosslinking agent gradually decreases as the aqueous agent is impregnated toward the center, and this results in a phenomenon where the crosslinking agent concentration is low and the degree of crosslinking is also low in the center. Consequently, the degree of crosslinking in the center is lower than that in the periphery, resulting in a variation in strength where the physical strength in the center is lower than that in the periphery.

[0070] In contrast, in the embodiment in which the base paper sheet 20 is impregnated by spraying a crosslinking agent solution before the folding process, the crosslinking agent solution is sprayed from above toward the surface of the base paper sheet 20. Therefore, the crosslinking agent solution can be sprayed uniformly onto the sheet surface, and the impregnation of the crosslinking agent in the thickness direction of the base paper sheet 20 is also uniform. As a result, the so-called crosslinking variation, where the degree of crosslinking differs between the periphery and the center as described above, does not occur, and a uniform degree of crosslinking is obtained throughout the entire base paper sheet 20, resulting in the advantage of obtaining uniform physical strength throughout the entire sheet. Therefore, the folded body 900 obtained by folding this base paper sheet 20 also has uniform physical strength. For these reasons, the manufacturing method of impregnating with a crosslinking agent before the folding process is preferable.

[0071] When the base paper sheet 20 is not impregnated with the crosslinking agent before the folding process, but the folded body 900 is impregnated with an aqueous agent containing the crosslinking agent after the folding process, it is preferable to employ a supply method in which the aqueous agent solution containing the crosslinking agent is sprayed from above the upright folded body 900, then the upright position is reversed and the folded body is lined up in the opposite position, and the aqueous agent solution is sprayed again from above in this state. Alternatively, the aqueous agent solution may be sprayed from both the left and right sides of the upright folded body 900. According to these supply methods, the aqueous agent containing the crosslinking agent can be uniformly impregnated, and variations in crosslinking can be prevented.

[0072] As described above, a manufacturing method for a hydrolyzable sheet according to the embodiment of the present invention is suitable in which the process of impregnating the base paper sheet with an aqueous agent is divided into two steps: a step of impregnating the base paper sheet with a crosslinking agent, which is a component of the aqueous agent, before the folding step (hereinafter referred to as step A), and a step of impregnating the base paper sheet with an aqueous agent consisting of components other than the crosslinking agent (a crosslinking agent-free agent) after the folding step (hereinafter referred to as step B). However, in this manufacturing method, when supplying the crosslinking agent solution to the base paper sheet before the folding step, a mixed solution obtained by mixing the crosslinking agent solution with an aqueous agent solution consisting of components other than the crosslinking agent (a crosslinking agent-free agent solution) may be supplied to the base paper sheet. In this case, the amount of crosslinking agent in the crosslinking agent solution is a portion of the total amount of crosslinking agent used in step A (for example, 80% of the total amount), and the amount of crosslinking agent-free agent in the crosslinking agent-free agent solution is a portion of the total amount of aqueous agent used in step B (for example, 20% of the total amount). Then, in step B after the folding process, when supplying the base paper sheet with a crosslinking agent-free chemical solution, a mixed solution obtained by mixing the crosslinking agent solution with the crosslinking agent-free chemical solution is supplied to the base paper sheet. In this case, the amount of crosslinking agent-free chemical solution used in step B is the remaining amount of the total amount of crosslinking agent-free chemical used in step B (for example, 80% of the total amount), and the amount of crosslinking agent in the crosslinking agent solution is the remaining amount of the total amount of crosslinking agent used in step A (for example, 20% of the total amount).

[0073] Furthermore, in the above-described embodiment, in step A, the entire amount of the crosslinking agent (100%) is used, and in step B, a portion of the total amount of the crosslinking agent-free agent used (for example, 20% of the total amount) is used, and a mixed solution of these crosslinking agent solution and crosslinking agent-free agent solution is supplied to the base paper sheet. On the other hand, in step B, the remaining amount of the crosslinking agent-free agent used in step B (for example, 80% of the total amount) is used, and this crosslinking agent-free agent solution is supplied to the base paper sheet. Furthermore, in step A, a portion of the total amount of crosslinking agent used in step A (for example, 80% of the total amount) may be used, and this crosslinking agent solution may be supplied to the base paper sheet. In step B, the entire amount (100%) of the water-free crosslinking agent may be used, and the remaining amount of crosslinking agent used in step A (for example, 20% of the total amount) may be used, and a mixed solution of these water-free crosslinking agent solutions and crosslinking agent solutions may be supplied to the base paper sheet.

[0074] As shown in Figures 2 and 3, the water-soluble sheet according to the embodiment of the present invention, manufactured as described above, has a uniformly formed uneven surface 120 consisting of numerous protrusions 130 and recesses 140 formed by embossing across its entire surface, and this uneven surface 120 forms a bulky portion 170, thereby configuring the water-soluble sheet according to the embodiment of the present invention as bulky paper. The numerous protrusions 130 are arranged linearly along the transport direction of the base paper sheet 20 in the manufacturing process (Z direction in Figure 2), thereby forming rows of protrusions 150, and the numerous recesses 140 are arranged linearly along the Z direction, thereby forming rows of recesses 160. These rows of protrusions 150 and rows of recesses 160 are arranged alternately and repeatedly along a direction perpendicular to the Z direction.

[0075] In the embodiment of the present invention, the shape of the protrusions 130 and recesses 140 of the uneven body 120 of the water-soluble sheet is arbitrary and is not limited to a circle as shown in Figure 2, but may be an ellipse, triangle, square, rhombus, etc., or it may be an irregular shape or a pattern such as a floral pattern.

[0076] The water-soluble sheet according to the embodiment of the present invention contains a water-soluble binder having a cross-linked structure. When electromagnetic wave drying is performed in the manufacturing process, the water-soluble sheet according to the embodiment of the present invention contains a water-soluble binder that has been subjected to electromagnetic wave drying. Furthermore, when far-infrared drying is performed in the manufacturing process, the water-soluble sheet according to the embodiment of the present invention contains a water-soluble binder that has been subjected to far-infrared drying. In the manufacturing method of the water-soluble sheet according to the embodiment of the present invention, the water-soluble binder is supplied from the outer surface side of the base paper sheet, so the impregnation area of ​​the water-soluble binder also includes the surface of the water-soluble sheet. Therefore, the water-soluble binder is also impregnated into the surface of the water-soluble sheet according to the embodiment of the present invention, thereby providing the necessary strength to the surface of the water-soluble sheet according to the embodiment of the present invention. As a result, when wiping a part to be cleaned using the water-soluble sheet according to the embodiment of the present invention, there is no risk of paper dust remaining on the dried surface after wiping, and the generation of paper dust can be prevented.

[0077] The water-soluble sheet according to the embodiment of this invention can be used as a cleaning product for cleaning toilets and the surrounding area, or as a wet wipe. The water-soluble sheet according to the embodiment of this invention has a predetermined strength when wet, does not tear during use, has a superior feel, and dissolves quickly when flushed down the toilet after use, without the risk of clogging sewer pipes, thus having excellent strength and water-soluble properties. Furthermore, the water-soluble sheet according to the embodiment of this invention can achieve further improvements in environmental considerations.

[0078] Furthermore, the water-soluble sheet according to the embodiments of the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention.

[0079] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0080] Furthermore, this invention can also take the following configuration. [1] Having a base paper sheet, The base paper sheet contains bamboo fiber pulp, A hydrolytic sheet in which the bamboo fiber pulp content is 10% to less than 100% by mass relative to the total mass of the base paper sheet.

[0081] [2] The aforementioned base paper sheet A hydrolytic sheet according to [1], comprising at least one selected from the group consisting of wood pulp, synthetic pulp, recycled paper pulp, synthetic pulp, semi-synthetic fibers, bleached softwood kraft pulp, bleached hardwood kraft pulp, kenaf, straw, cotton, and silkworm cocoons.

[0082] [3] Having a base paper sheet, The base paper sheet is a water-soluble sheet made from bamboo fiber pulp.

[0083] [4] Using a base paper sheet impregnated with a water-soluble binder, An embossing step is performed on the base paper sheet to form a bulky area on the base paper sheet with numerous indentations and protrusions, After the embossing process, a water impregnation process is performed in which water is supplied to the base paper sheet from the outside and the water is impregnated into the base paper sheet. After the water impregnation step, a drying step is performed to dry the base paper sheet, After the drying process, a folding process is performed in which the base paper sheet is folded, A method for producing a hydrolyzable sheet, comprising an aqueous agent impregnation step of supplying an aqueous agent to the base paper sheet and impregnating the base paper sheet with the aqueous agent.

[0084] [5] A method for producing a hydrolyzable sheet according to [4], wherein a crosslinking agent that undergoes a crosslinking reaction with the water-soluble binder to form a crosslinked structure of the water-soluble binder is impregnated into the base paper sheet before the folding step.

[0085] [6] A method for producing a hydrolyzable sheet according to [4] or [5], wherein a crosslinking agent that undergoes a crosslinking reaction with the water-soluble binder to form a crosslinked structure of the water-soluble binder is impregnated into a base paper sheet impregnated with the water-soluble binder before the drying step. [Explanation of Symbols]

[0086] 20...Base paper sheets, 510...Water, 1000... Aqueous chemical solution, 120...uneven body, 170... Bulky section.

Claims

1. Having a base paper sheet, The base paper sheet contains bamboo fiber pulp, A hydrolytic sheet in which the bamboo fiber pulp content is 10% to less than 100% by mass relative to the total mass of the base paper sheet.

2. The aforementioned base paper sheet A hydrolytic sheet according to claim 1, comprising at least one selected from the group consisting of wood pulp, synthetic pulp, recycled paper pulp, synthetic pulp, semi-synthetic fibers, bleached softwood kraft pulp, bleached hardwood kraft pulp, kenaf, straw, cotton, and silkworm cocoons.

3. Having a base paper sheet, The base paper sheet is a water-soluble sheet made from bamboo fiber pulp.

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