Paper-containing structure, and method for producing paper-containing structure

Abstract

In this paper-containing structure, a paper-containing sheet (2) has a first surface (1a) and a second surface (1b), in which a first hydroxyl-group-rich region (11) is formed in the first surface (1a), and a second hydroxyl-group-rich region (14) is formed in the second surface (1b). In each of the hydroxyl-group-rich regions (11, 14), a tensile stress is generated and is balanced with an anti-deformation force of the paper-containing sheet (2) to form a first stable state, thereby keeping a first shape. When the paper-containing structure (1) has a second shape, the forces are balanced with each other to form a second stable state, thereby keeping the second shape. The shape of the paper-containing structure (1) is switched between the first shape and the second shape in at least one direction upon the application of a trigger force.

Description

Paper-containing structure and method for manufacturing the paper-containing structure

[0001] The present invention relates to a paper-containing structure whose three-dimensional shape changes when a trigger force is applied, and a method for manufacturing the paper-containing structure. This application claims priority based on Japanese Patent Application No. 2022-166403, filed on October 17, 2022, the contents of which are incorporated herein by reference.

[0002] Origami technology has the advantage of being able to create a variety of three-dimensional structures by folding a single sheet of paper. By devising folding patterns, it is possible to repeatedly use the functions of unfolding and retracting, and it is possible to create structures with relatively high mechanical strength, so it is expected to be applied in a variety of fields. For example, origami technology can be expected to be applied to the manufacturing of three-dimensional electronic devices, the production of lightweight and inexpensive shock-absorbing materials, and space-saving by folding sheets.

[0003] In this context, autonomous paper folding technology, which allows paper to bend by itself by applying some external force to the paper, has attracted attention, and this technology is sometimes referred to as "self-folding." The development of such autonomous paper folding technology is expected to lead to significant advances in the utilization of the properties of origami described above.

[0004] One such folding technique that has been reported so far is to place a material on the paper that responds to external stimuli, such as electric current or heat, and then use the material's response to the applied stimuli to make the paper fold autonomously.

[0005] However, such folding techniques have the problem that the environment in which they can be used may be limited because they require the supply of some kind of energy, such as electric current or heat, and furthermore, they have the problem of being expensive because the paper must be modified with special materials.

[0006] As a method for solving such problems, a method has been disclosed in which an aqueous solution containing 2-propanol is ejected onto paper using an inkjet printer and then dried (see Non-Patent Document 1). This method has the advantage that it does not require the supply of energy such as electric current or heat to the paper, and it does not require the paper to be modified with a special material.

[0007] Hiroki Shigemune, Shingo Maeda, Yusuke Hara, and Shuji Hashimoto. "Design of paper mechatronics: Towards a fully printed robot" Proceedings of 2014 IEEE / RSJ International Conference on Intelligent Robots and Systems (IROS 2014)

[0008] The method disclosed in Non-Patent Document 1 is useful in that it can solve the problems of other methods to date, but further improvement is desired in order to apply it to a practical method for producing three-dimensional structures.

[0009] The present invention aims to provide a novel, highly practical paper-containing structure that utilizes origami techniques, and a method for manufacturing the same.

[0010] The present invention provides the following aspects: [1] A paper-containing structure formed from a dry paper-containing sheet containing paper, the paper-containing sheet having a first surface and a second surface that are opposite each other, wherein a first hydroxyl group-rich region having a higher hydroxyl group density than other regions on the first surface is formed on the first surface. A second hydroxyl group-rich region having a higher hydroxyl group density than other regions on the second surface is formed on the second surface, and tensile stress is generated in each of the first hydroxyl group-rich region and the second hydroxyl group-rich region. When the paper-containing structure is in a first shape, the tensile stress in the first hydroxyl group-rich region on the first surface and the tensile stress in the second hydroxyl group-rich region on the second surface balance with the resistance to deformation of the paper-containing sheet to form a first stable state and maintain the first shape. Furthermore, when the paper-containing structure is in a second shape, the tensile stress in the first hydroxyl group-rich region on the first surface balances with the resistance to deformation of the paper-containing sheet to form a second stable state and maintain the second shape. The paper-containing structure is capable of switching between the first shape and the second shape in at least one direction upon application of a trigger force to a portion of the paper-containing structure.

[0011] According to aspect [1], by applying a trigger force to a part of the paper-containing structure having a first hydroxyl group-rich region and a second hydroxyl group-rich region, the balance between the tensile stress and the deformation resistance force within the paper-containing structure changes, causing the paper-containing structure to switch in at least one direction between a first shape and a second shape. This switching action can realize various functions such as grasping, storing, switching, and moving an object, and opening and closing a valve.

[0012] [2] In the paper-containing structure of the first aspect, the first hydroxyl group high concentration region and the second hydroxyl group high concentration region have a wavenumber of 3331 cm －１ When infrared light is reflected from a surface portion of the paper-containing structure by a total reflection measurement method using infrared light of a wave number of 3331 cm and an infrared absorption spectrum of the surface portion is measured, the transmittance of the infrared light may be lower than that of the other portion. －１The infrared transmittance of the high hydroxyl group concentration region is not limited, but may be lower by 0.01% or more, 0.1% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, or 10% or more than that of the other regions.

[0013] [3] In the paper-containing structure according to the first or second aspect, the paper-containing sheet may have one or more notches formed therein, and the first stable state and the second stable state may be formed by the notches. A trigger force may be applied to the notches.

[0014] [4] In the paper-containing structure of any of Aspects 1 to 3, the trigger force may be generated by water penetration into the paper-containing structure, a change in humidity in the environment in which the paper-containing structure is placed, localized compression of the paper-containing structure, heating of the paper-containing structure, cooling of the paper-containing structure, cutting of a portion of the paper-containing structure, or application of an external force to the paper-containing structure. The trigger force is a stimulus to the paper-containing sheet, and may be a force applied to the paper-containing sheet or a force generated within the paper-containing sheet. For example, the trigger force may be a localized temperature change of the paper-containing sheet due to irradiation with strong light, a bullet collision, burning off a portion of the paper-containing sheet with a laser beam, vibration of the paper-containing sheet with sound waves, or a pressure force on the paper-containing sheet due to the blowing of air or wind.

[0015] [5] In the paper-containing structure of any one of Aspects 1 to 4, the paper-containing structure may be bidirectionally switched between the first shape and the second shape by applying the trigger force to a part of the paper-containing structure. The method and type of trigger force applied when changing from the first shape to the second shape may be different from the method and type of trigger force applied when changing from the second shape to the first shape. The paper-containing structure may have a third shape or a fourth shape.

[0016] [6] A gripping tool for gripping an article, comprising the paper-containing structure of any one of aspects 1 to 5, wherein the first shape is an article-releasing shape with an open end, and the second shape is an article-gripping shape with a narrowed end, and the trigger force is generated by the gripping tool colliding with the article or by the gripping tool contacting a support surface on which the article is supported, thereby causing the paper-containing structure to change from the article-releasing shape to the article-gripping shape and grip the article. The end can be set to match the position of the article to be gripped, and may be the bottom end, side end, or top end of the paper-containing sheet.

[0017] [7] A drone gripping device comprising the gripping device according to aspect 6, characterized in that the gripping device has a fixing portion at its center that is fixed to the support portion of the drone. In the case of drones, the light weight of the gripping device and the lack of a separate opening / closing mechanism are significant advantages. It can also be used for ultra-small drones. Furthermore, the drone gripping device of the present invention can change from the second shape to the first shape, grip an item to a destination point, and release the item from the drone at the destination point to drop or place it.

[0018] [8] A cushioning material comprising the paper-containing structure of any one of aspects 1 to 5 and used to arrange one or more items therein, wherein the paper-containing structure has an origami structure, and the first shape is a contracted shape without pockets or a flat shape without pockets when the paper-containing structure is folded, and the second shape is an expanded shape in which the paper-containing structure is unfolded to form one or more pockets, and the contracted shape or flat shape may be changed to the expanded shape by applying a trigger force to a portion of the paper-containing structure. In this case, the paper-containing sheet may be, for example, printed with a required pattern of first hydroxyl-rich regions and second hydroxyl-rich regions, and then folded into a Miura fold or egg box shape, or may have creases. The pocket may have a honeycomb structure.

[0019] [9] An origami device comprising the paper-containing structure of any one of aspects 1 to 5, and at least one of an electronic element and wiring provided on at least one of the first surface and the second surface of the paper-containing structure. The electronic element may be an active element alone or a combination of active elements (e.g., a transistor, IC, diode, or operational amplifier), or a passive component such as a resistor, coil, or capacitor. It may also be a printed antenna, relay, switch, connector, printed circuit board, or terminal. The wiring may be, for example, a thin copper or aluminum printed on the paper-containing sheet. It is also possible to apply a trigger force to the paper-containing sheet using a heating element or solenoid, causing the paper-containing sheet to deform between the first and second shapes.

[0020]

[10] A cushioning material comprising the paper-containing structure described in any one of aspects 1 to 5 and used to arrange one or more items therein, wherein the paper-containing structure has an origami structure, the first shape being a flat plate shape with no pockets when the paper-containing structure is unfolded, and the second shape being an unfolded shape with one or more pockets when the paper-containing structure is folded, and the flat shape can be changed to the unfolded shape by applying a trigger force to a portion of the paper-containing structure.

[0021]

[11] A cushioning material comprising a paper-containing structure according to any one of aspects 1 to 5, wherein the paper-containing structure has one or more openings, and the first hydroxyl group-rich region and the second hydroxyl group-rich region arranged around the openings, the first shape being a contracted shape without a pocket when the paper-containing structure is folded or a flat shape when the paper-containing structure is unfolded, and the second shape being a three-dimensional shape having a cylindrical wall portion standing on the periphery of the opening and a support portion extending from the cylindrical wall portion, and the paper-containing structure can change from the contracted shape or the flat shape to the three-dimensional shape by applying a trigger force to a portion of the paper-containing structure. The cylindrical wall portion and the support portion may have a honeycomb structure as a whole.

[0022]

[12] A method for producing a paper-containing structure according to any one of aspects 1 to 5, comprising the steps of applying a liquid containing water to the first surface and the second surface of the paper-containing sheet in areas where the first hydroxyl group high concentration region and the second hydroxyl group high concentration region are to be formed, and drying the liquid.

[0023]

[13] In the paper-containing structure described in any one of Aspects 1 to 5, a flexible protective film may be attached to at least a portion of at least one of the first and second surfaces of the paper-containing sheet. By covering at least a portion of the paper-containing sheet with the protective film, particularly in areas that come into contact with water, unnecessary moisture is prevented from penetrating the paper-containing sheet, and the deformation function of the paper-containing sheet due to the first high hydroxyl group concentration region and the second high hydroxyl group concentration region can be maintained. Furthermore, when the paper-containing structure is used to hold a moisture-rich item such as fruit, forming a protective film in the area that comes into contact with the item prevents the paper-containing structure from absorbing moisture from the item, thereby maintaining the freshness of the fruit. Furthermore, the friction coefficient of the surface that comes into contact with the fruit or other item is increased in the area where the protective film is coated, thereby improving the positional stability of the item when stored.

[0024]

[14] In the paper-containing structure described in any one of Aspects 1 to 5, flexible protective films may be attached to the first and second surfaces of the paper-containing sheet. By sandwiching the paper-containing sheet between the protective films in this manner, even if the paper-containing structure 1 is wet or placed in a humid environment, unnecessary moisture does not penetrate the paper-containing sheet, and the deformation function of the paper-containing sheet due to the first hydroxyl group high concentration region and the second hydroxyl group high concentration region can be maintained. Furthermore, when the paper-containing structure is used to hold a moisture-rich item such as fruit, the paper-containing structure can be prevented from absorbing moisture from the item. This allows the freshness of the fruit or other items to be maintained. Furthermore, by covering the surface with a protective film, the friction coefficient of the surface that comes into contact with the item, such as fruit, is increased, thereby improving the positional stability of the item when stored. The edge of the paper-containing sheet may be covered with the material of the protective film, forming an edge protective film. In this case, moisture resistance can be further improved and peeling of the protective film from the edge can be suppressed.

[0025] According to the present invention, by applying a trigger force to a portion of a paper-containing structure having a first hydroxyl group-rich region and a second hydroxyl group-rich region, the balance between the tensile stress and the deformation resistance force within the paper-containing structure changes, causing the structure to switch in at least one direction between a first shape and a second shape. This switching action can realize various functions.

[0026] 1 is an enlarged cross-sectional view illustrating the principle of the paper-containing structure according to the present invention. FIG. 1 is an enlarged cross-sectional view illustrating the principle of the paper-containing structure according to the present invention. FIG. 2 is an enlarged cross-sectional view illustrating the principle of the paper-containing structure according to the present invention. FIG. 3 is an enlarged cross-sectional view illustrating an example of a high hydroxyl group concentration region in the present invention. FIG. 4 is an enlarged cross-sectional view illustrating the function of a high hydroxyl group concentration region in the present invention. FIG. 5 is an enlarged cross-sectional view illustrating the function of a high hydroxyl group concentration region in the present invention. FIG. 6 is a cross-sectional view illustrating a method for measuring the concentration of hydroxyl groups. FIG. 7 is a graph illustrating the high hydroxyl group concentration region in the present invention. FIG. 8 is a graph illustrating the high hydroxyl group concentration region in the present invention. FIG. 9 is a graph illustrating the high hydroxyl group concentration region in the present invention. FIG. 10 is a perspective view illustrating an embodiment of a paper-containing structure according to the present invention. FIG. 11 is a plan view illustrating an embodiment of a paper-containing structure according to the present invention. FIG. 12 is a perspective view illustrating an embodiment of a paper-containing structure according to the present invention. FIG. 13 is a plan view illustrating an embodiment of a paper-containing structure according to the present invention. FIG. 14 is a perspective view illustrating another embodiment of a paper-containing structure according to the present invention. FIG. 15 is a perspective view illustrating another embodiment of a paper-containing structure according to the present invention. FIG. 16 is a plan view illustrating another embodiment of a paper-containing structure according to the present invention. 19 is a cross-sectional view showing the operation of another embodiment of the present invention. FIG. 19 is a plan view showing a test piece according to an embodiment of the present invention. FIG. 19 is a graph showing test results of the amount of movement and load using the test piece of FIG. 18. FIG. 19 is a graph showing paper thickness and angle change using the test piece of FIG. 18. FIG. 19 is a graph showing horizontal printing width and angle change using the test piece of FIG. 18. FIG. 20 is a perspective view showing another embodiment of a paper-containing structure according to the present invention. FIG. 20 is a plan view showing another embodiment of a paper-containing structure according to the present invention. FIG. 20 is a plan view showing another embodiment of a paper-containing structure according to the present invention. FIG. 20 is a front view showing another embodiment of a paper-containing structure according to the present invention. FIG. 20 is a perspective view showing another embodiment of a paper-containing structure according to the present invention. FIG. 20 is a front view showing an article-releasing state of a drone-mounted gripper as another embodiment of a paper-containing structure according to the present invention. FIG. 21 is a front view showing an article-gripping state of a drone-mounted gripper as another embodiment of a paper-containing structure according to the present invention.1 is a plan view showing another embodiment of a paper-containing structure according to the present invention; FIG. 2 is a plan view showing another embodiment of a paper-containing structure according to the present invention; FIG. 3 is a perspective view showing another embodiment of a paper-containing structure according to the present invention; FIG. 4 is a plan view showing another embodiment of a paper-containing structure according to the present invention; FIG. 5 is a front view showing another embodiment of a paper-containing structure according to the present invention; FIG. 6 is a plan view showing another embodiment of a paper-containing structure according to the present invention; FIG. 7 is a plan view showing another embodiment of a paper-containing structure according to the present invention; FIG. 8 is a perspective view showing another embodiment of a paper-containing structure according to the present invention; FIG. 9 is a perspective view showing another embodiment of a paper-containing structure according to the present invention; FIG. 10 is a perspective view showing another embodiment of a paper-containing structure according to the present invention; FIG. 11 is an enlarged cross-sectional view showing another embodiment of a paper-containing structure according to the present invention; FIG. 12 is an enlarged cross-sectional view showing another embodiment of a paper-containing structure according to the present invention; FIG. 13 is an enlarged cross-sectional view showing another embodiment of a paper-containing structure according to the present invention; FIG. 14 is a plan view showing a sensing pad as another embodiment of a paper-containing structure according to the present invention; FIG. 15 is a perspective view showing the sensing pad fixed to a human head; FIG. 16 is a partially broken plan view showing an absorbent pad as another embodiment of a paper-containing structure according to the present invention; FIG. 17 is a cross-sectional view of the absorbent pad; FIG. 18 is a plan view showing a conical structure as another embodiment of a paper-containing structure according to the present invention. 1 is a front photograph showing the state before a trigger force is applied to the conical structure. FIG. 2 is a front photograph showing the state after a trigger force is applied to the conical structure. FIG. 3 is a cross-sectional view showing a catalyst unit as another embodiment of the paper-containing structure according to the present invention. FIG. 4 is a photograph of a cushioning material without a protective film as another embodiment of the paper-containing structure according to the present invention before deformation. FIG. 5 is a photograph of the cushioning material without the protective film after deformation. FIG. 6 is a photograph of a cushioning material with a protective film as another embodiment of the paper-containing structure according to the present invention before deformation. FIG. 7 is a photograph of the cushioning material with the protective film after deformation. FIG. 8 is a photograph showing a usage mode of the cushioning material with the protective film. FIG. 9 is an explanatory diagram showing a moisture absorption experiment method for investigating the difference in moisture absorbency between a paper-containing sheet with and without a protective film formed thereon. FIG. 10 is a graph showing the results of the moisture absorption experiment.

[0027] Hereinafter, embodiments of a paper-containing structure and a method for manufacturing a paper-containing structure according to the present invention will be described with reference to the drawings.

[0028] 1A to 1C are enlarged cross-sectional views illustrating the operating principle of the present invention. As shown in FIGS. 1A to 1C, the paper-containing structure of the present invention is a paper-containing structure formed from a dry paper-containing sheet 2 containing paper. The paper-containing sheet 2 has a first surface 1a and a second surface 1b, which are opposite surfaces. A first hydroxyl group-rich region 11 having a higher hydroxyl group density than other regions on the first surface 1a is formed on the first surface 1a by impregnating a portion of the paper-containing sheet 2 with a liquid 9 consisting of water or an aqueous solution. A second hydroxyl group-rich region (not shown) having a higher hydroxyl group density than other regions on the second surface 1b is also formed on the second surface 1b.

[0029] The first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region each experience a tensile stress in a direction parallel to the paper-containing sheet 2. The tensile stress in the first hydroxyl group high concentration region 11 on the first surface 1a, the tensile stress in the second hydroxyl group high concentration region on the second surface 1b, and the anti-deformation force of the paper-containing sheet 2 itself counteract each other when the paper-containing structure 1 is in a first shape to form a first stable state and maintain the first shape, and also counteract each other when the paper-containing structure is in a second shape to form a second stable state and maintain the second shape. The present invention is characterized in that the paper-containing structure 1 can be switched between the first shape and the second shape in at least one direction by applying a trigger force to a portion thereof.

[0030] As shown in FIG. 1A, water 9 is applied to and penetrates the first surface 1a of the paper-containing sheet 2 to form a first hydroxyl group high concentration region 11. １Taking this into consideration, an appropriate amount of water 9, but not an excessive amount, is applied to the first surface 1a. As a result, water 9 penetrates into the paper-containing sheet 2 from the first surface 1a, as shown in Figures 1B and 1C. Figure 1B shows a state in which the paper-containing sheet 2 swells slightly due to the penetration of water 9, causing the paper-containing sheet 2 to warp so that the first surface 1a becomes convex. Typically, after this state has passed, the water 9 evaporates, resulting in the unwarped state shown in Figure 1C, and tensile stress remaining in the first hydroxyl group high concentration region 11.

[0031] 2, the penetration of water 9 may reach the second surface 1b from the first surface 1a. In this case, a first hydroxyl group-rich region having a wide width or a high hydroxyl group concentration is formed on the first surface 1a, and a second hydroxyl group-rich region having a narrow width or a low hydroxyl group concentration is formed on the second surface 1b.

[0032] 3, a first hydroxyl group high concentration region 12 in which the penetration of water 9 does not reach the second surface 1b from the first surface 1a, and a first hydroxyl group high concentration region 13 in which the penetration of water 9 reaches the second surface 1b from the first surface 1a may be formed. In this case as well, a difference in tensile stress occurs between the first surface 1a side and the second surface 1b side, and the effect of the present invention can be achieved.

[0033] The paper-containing sheet 2 is a sheet made of paper itself (i.e., a paper sheet) or a sheet mainly composed of paper and containing cellulose as a main component. As the paper sheet, for example, a relatively thick paper such as tracing paper, in which bundles of cellulose fibers are compressed by being subjected to strong pressing during the manufacturing process, is suitable.

[0034] A sheet primarily made of paper may contain paper and other components. The other components can be selected arbitrarily depending on the purpose as long as the effects of the present invention are not impaired. Specific examples of other components include resins, silica gel, cosmetic agents such as calcium carbonate and clay, glossing agents, and binders such as starch and PVA.

[0035] When applying water 9 to the paper-containing sheet 2, not only pure water but also other liquids such as an aqueous solution containing various water-soluble compounds or an aqueous solution containing a small amount of an organic solvent such as alcohol may be used. In this case, the solute in the aqueous solution may penetrate into the paper-containing sheet 2 and remain. Examples of solutes in aqueous solutions include organic solvents (2-propanol, ethylene glycol, etc.) used to adjust the viscosity and surface tension of the inkjet ink, various electrolytes such as salts, and dyes. The aqueous solution may contain only one type of solute, or two or more types. For example, adding a dye has the advantage of making it easier to visually confirm the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14.

[0036] The concentration of components other than water in the aqueous solution is preferably as low as possible, for example, preferably 5% by mass or less of the entire liquid, more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0037] Non-Patent Document 1 discloses a technology for autonomously folding a paper sheet using an aqueous solution containing 2-propanol, which contains water and 2-propanol in a mass ratio of "water:2-propanol = 90:10." However, although lower alcohols such as 2-propanol are highly miscible with water, they do not have the ability to autonomously fold paper-containing sheets, or if they do, the ability is significantly inferior to that of water. Therefore, when compared at the same amount, when an aqueous solution containing 2-propanol is used, the rate of autonomous deformation of the paper-containing sheet is slower and the folding angle remains small compared to when pure water or an aqueous solution in which the majority of the liquid component is water is used.

[0038] In contrast, the paper-containing structure and its manufacturing method of the present invention have a significant advantage in that the autonomous deformation of the paper-containing sheet can be achieved at a faster speed and at a larger bending angle than when an aqueous solution containing 2-propanol at a high concentration is used. However, various liquids can also be used in the paper-containing structure manufacturing method of the embodiment of the present invention as long as the liquid is low in concentration. In the paper-containing structure manufacturing method of the embodiment of the present invention, it is also possible to use an aqueous solution containing 2-propanol as long as the concentration is low as described above.

[0039] In the above process, when a liquid such as water or an aqueous solution is applied to and penetrates the paper-containing sheet 2, two types of aqueous solutions with different concentrations of the additive may be applied separately to different regions of the paper-containing sheet 2. The solute is not particularly limited as long as it is water-soluble, and can be selected arbitrarily. The aqueous solution is preferably neutral.

[0040] Of the solutes, the salt may be either an organic salt or an inorganic salt, but is preferably an inorganic salt. Examples of the inorganic salt include alkali metal chlorides such as lithium chloride (LiCl, hydration parameter: 7.1), sodium chloride (NaCl, hydration parameter: 3.5), potassium chloride (KCl, hydration parameter: 1.9), and rubidium chloride (RbCl, hydration parameter: 1.2); alkali metal bromides such as lithium bromide (LiBr, hydration parameter: 7.6), sodium bromide (NaBr, hydration parameter: 4.2), potassium bromide (KBr, hydration parameter: 2.1), and rubidium bromide (RbBr, hydration parameter: 0.9); alkali metal bromides such as lithium iodide (LiI, hydration parameter: 9.0), sodium iodide (NaI, hydration parameter: 5.5), potassium iodide (KI, hydration parameter: 2.5), and rubidium iodide (RbI, hydration parameter: 0.6); magnesium chloride (MgCl ２ , hydration parameter: 13.7), calcium chloride (CaCl ２ , hydration parameter: 12.0), strontium chloride (SrCl ２ chlorides of Group 2 metals such as magnesium bromide (MgBr ２ , hydration parameter: 17.0), calcium bromide (CaBr ２ , hydration parameter: 14.6), strontium bromide (SrBr ２ bromides of Group 2 metals such as magnesium iodide (MgI ２ , hydration parameter: 19.0), calcium iodide (CaI ２ , hydration parameter: 17.0), strontium iodide (SrI ２iodides of Group 2 metals such as manganese chloride (MnCl ２ , hydration parameter: 11.0), ferrous chloride (FeCl ２ , hydration parameter: 12.0), cobalt chloride (CoCl ２ , hydration parameter: 13.0), nickel chloride (NiCl ２ , hydration parameter: 13.0), and the like.

[0041] The permeation and drying of water 9 in the aqueous solution can be suppressed by adding the above-mentioned solute to the paper-containing sheet 2. If a small suppression effect is acceptable, a solute with a hydration parameter of 0.5 to 9 can be selected, and if a large suppression effect is desired, a solute with a hydration parameter of 15 to 20 can be selected, although this is not limited in the present invention.

[0042] The temperature at which the water 9 is applied to and penetrates the paper-containing sheet 2 is not limited, but may be, for example, 10 to 35° C. Under such temperature conditions, the water 9 can penetrate the paper-containing sheet 2 more effectively.

[0043] The relative humidity when the water 9 is applied to and penetrates the paper-containing sheet 2 is preferably 10 to 80%, and may be, for example, 20 to 65% or 20 to 40%. Under such relative humidity conditions, the water 9 can penetrate the paper-containing sheet 2 more effectively.

[0044] After the penetration step, the paper-containing sheet 2 having a water 9 concentration gradient therein is dried. When the paper-containing sheet 2 having a water concentration gradient is dried, the cellulose in the paper-containing sheet 2 shrinks in the area 11 containing the water 9, generating tensile stress, as shown in FIG. 4A, for example. This causes the paper-containing sheet 2 to bend so that the first surface 1a becomes concave. As drying progresses, the angle of bending increases. As shown in FIG. 4B, a three-dimensional structure 10 is formed when drying is complete. When the paper-containing sheet 2 is dried while suppressing this deformation, the paper-containing sheet 2 can generate tensile stress in the high hydroxyl group concentration region.

[0045] Cellulose molecules are bonded to each other by hydrogen bonds in the paper-containing sheet 2. When water 9 is permeated into the paper-containing sheet 2, the first surface 1a side expands, and it is presumed that the water molecules break the hydrogen bonds between cellulose molecules in the paper-containing sheet 2, creating a state in which water molecules are interposed between cellulose molecules, and forming intermolecular bonds of cellulose molecule-water molecule-cellulose molecule.

[0046] The paper-containing sheet 2 is produced by sandwiching pulp between press rolls to remove moisture, and then heating the sheet while applying pressure with the press rolls. Due to this manufacturing method, the paper-containing sheet 2 is initially in a state of compressive strain caused by an external force. When water 9 is permeated into such a paper-containing sheet 2 and then dried, as the water 9 in the paper-containing sheet 2 decreases due to drying, the cellulose molecules in the paper-containing sheet 2 are again bonded to each other by hydrogen bonds. At this time, the paper-containing sheet 2 is in a stable state with the strain reduced or eliminated compared to its initial state, and is presumed to shrink more than before the permeation of water 9. The contraction force generated at this time is presumed to cause the paper-containing sheet 2 to autonomously bend in the high hydroxyl group concentration region, as shown in Figure 4B.

[0047] Although the present invention does not limit the formation of the first and second water concentration gradient regions on the paper-containing sheet 2, printing using an inkjet printer can be suitably employed to apply a complex shape. When an inkjet printer is used, a liquid consisting of water or an aqueous solution is ejected from the inkjet printer onto the paper-containing sheet 2, adhered to the paper-containing sheet 2, and allowed to penetrate the paper-containing sheet 2.

[0048] [Method for Measuring Hydroxyl Group Density] Figure 5 shows the measurement principle of the attenuated total reflection (ATR) method for measuring hydroxyl group density. A transparent crystal 15, which serves as an optical waveguide, is placed on the paper-containing sheet 2 as a sample. Infrared light is incident through this crystal 15 while continuously changing wavelengths, and the infrared light is irradiated from the underside of the crystal 15 onto a region at a depth dp in the surface layer of the paper-containing sheet 2. The reflected light that penetrates and is reflected inside the paper-containing sheet 2 re-enters the light-receiving sensor through the crystal 15, and the transmittance for each wavenumber of the incident light is determined by the light-receiving sensor. In the figure, θ is the angle of incidence, and in this specification, the value is taken as 45°. The penetration depth dp at which reflected light occurs varies depending on the sample, but is generally in the range of 0.5 to 5 μm. The device used for the actual measurement was a Fourier transform infrared spectrophotometer manufactured by Shimadzu Corporation, product name "IRAffinity-1S," and the measurement conditions were: resolution: 4 cm －１ , apodization function (function used in Fourier transform): Happ-Genzel, number of integrations: 30.

[0049] 6 and 7 show examples of data obtained by the ATR method of FIG. 5. FIGS. 6 to 9 show the transmittance (%) spectra obtained for the front surface of the paper-containing sheet 2 before water penetration, the front surface of the paper-containing sheet 2 after printing and drying, and the back surface of the paper-containing sheet 2, while continuously changing the wave number of infrared rays. As shown in these graphs, the wave number of 3331 (cm －１ ), the transmittance drops significantly due to the high density of hydroxyl groups, resulting in a downward peak. －１ ) and comparing the transmittance, it was proven that the density of hydroxyl groups in the surface layer portion of the paper-containing sheet 2 can be compared.

[0050] 8 and 9 show the results of comparative experiments conducted to confirm whether other factors were causing the decrease in infrared transmittance of the paper-containing sheet 2. In these comparative experiments, the infrared spectra of the front and back surfaces of the paper-containing sheets that had been subjected to four types of treatment were measured while continuously changing the infrared wave number. "Water surface" indicates the surface of the paper-containing sheet 2 after water has been printed on its surface and dried, "Water back" indicates the back surface of the paper-containing sheet 2 after water has been printed on its surface and dried, "Mold back" indicates the back surface of the paper-containing sheet 2 after the paper-containing sheet 2 has been pressed with a load of 1 ton / (40 mm x 40 mm), "Mold surface" indicates the surface of the same pressed paper-containing sheet 2, "Compressed back" indicates the back surface of the paper-containing sheet 2 after the paper-containing sheet 2 has been sandwiched between aluminum blocks and pressed with a load of 3 ton / (40 mm x 40 mm), "Compressed surface" indicates the surface of the same paper-containing sheet 2 after sandwiching between aluminum blocks and pressing, "Hand-folded back" indicates the surface of the paper-containing sheet 2 after hand-creasing, and "Hand-woven surface" indicates the back surface of the paper-containing sheet 2 after hand-creasing. As shown in these graphs, the wavenumber of 3331 (cm －１ The only graph showing a significant decrease in transmittance due to the high density of hydroxyl groups before and after the water penetration test was the "water surface" graph. Therefore, it was proven that the decrease in transmittance due to the hydroxyl group concentration was the result of water penetration.

[0051] [First Embodiment] Figures 10 to 12 show a paper-containing structure 20, which is a specific first embodiment of the paper-containing structure of the present invention. In this paper-containing structure 20, a band-shaped first hydroxyl group-rich region 11 extending in the short-side direction is formed in the widthwise center of the first surface 1a of a rectangular paper-containing sheet 2 by printing with water or an aqueous solution, for example. Furthermore, a band-shaped second hydroxyl group-rich region 14 is formed on the second surface 1b of the paper-containing sheet 2 at a fixed distance from both ends of the long side by printing with water or an aqueous solution, for example. The paper-containing sheet 2 is then sufficiently dried. At the center of both longitudinal ends of the first hydroxyl group-rich region 11, weakened lines 22 may be formed in advance by intermittently cutting the paper-containing sheet 2 in a dotted line pattern or by shallowly incising the paper-containing sheet 2, as shown in Figure 11. The length of the weakened line 22 may be such that it reaches the second hydroxyl group-rich region 14 or does not.

[0052] Note that the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 may have a hydroxyl group concentration that is not constant in the horizontal direction and / or thickness direction of the paper-containing sheet 2 (i.e., a gradient). A concentration gradient occurs in the thickness direction due to diffusion, so a gradient typically occurs when applying from one side. For convenience of explanation, the long and short sides are described above, but the long and short sides may be reversed. Furthermore, the paper-containing sheet 2 may be square, or may have any shape, such as a circle, ellipse, triangle, pentagon, or irregular shape. The shapes of the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 may not be linear bands, but may be curved, intermittent dotted lines, or may intersect at an acute or obtuse angle without being perpendicular, or the width of the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 may vary in the longitudinal direction. The above points are also common to other embodiments unless otherwise noted.

[0053] After the drying process, the paper-containing sheet 2 is curved along the mountain fold line 5 so that the second surface 1b side is concave along the second hydroxyl group high concentration region 14 due to tensile stress that tends to shrink the sheet in the width direction within the second hydroxyl group high concentration region 14. Meanwhile, tensile stress that tends to shrink the sheet in the width direction of the first hydroxyl group high concentration region 11 also occurs within the first hydroxyl group high concentration region 11. However, because the second hydroxyl group high concentration region 14 curves first, the paper-containing sheet 2 has a high resistance to deformation against a force bending the sheet in the long side direction, and almost no deformation occurs due to the tensile stress of the second hydroxyl group high concentration region 14. As a result, the long sides of the sheet are curved in the first shape shown in Figure 10, and the tensile stress of the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the resistance to deformation of the sheet 2 are balanced, maintaining a stable shape.

[0054] Next, a downward force is applied to the center of the first surface 1a of the paper-containing structure 20, which is stable in the first shape shown in Figure 10, or incisions 21 are made at both ends of the first hydroxyl group high concentration region 11, or both, or if a weakened line 22 is present, the weakened line 22 is torn. This forms incisions 21 perpendicular to the second hydroxyl group high concentration region 14, or reduces the width of the second hydroxyl group high concentration region 14 due to the incisions 21, thereby reducing the deformation resistance of the paper-containing sheet 2. Then, due to the tensile stress from the first hydroxyl group high concentration region 11, the paper-containing sheet 2 bends along the width direction of the first hydroxyl group high concentration region 11, deforming into a V-shaped cross section concave toward the first surface 1a, and stopping while maintaining this second shape. In the second shape, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress from the second hydroxyl group high concentration region 14, and the deformation resistance of the paper-containing sheet 2 are balanced, so no further deformation occurs.

[0055] Therefore, with this paper-containing structure 20, in the first shape shown in Fig. 10, by applying a downward force to the center of the first surface 1a, by making incisions 21 at both ends of the first hydroxyl group high concentration region 11, or by doing both, or by ripping the weakened lines 22 if any, the paper-containing structure 20 changes to the second shape shown in Fig. 12, and can perform various functions in the process. For example, by forming a V-shape in the second shape, the paper-containing structure 20 can pinch another item, perform some kind of switching operation at the moving end, or press another item by utilizing the increased overall thickness of the paper-containing structure 20.

[0056] Furthermore, the paper-containing structure 20 can be formed simply and at low cost by applying water or an aqueous solution to the paper-containing sheet 2 and drying it, and since it can be made in a variety of sizes and is light in weight, it can be used for a wide variety of purposes.

[0057] Although a pushing force is used as the trigger force in the above explanation, in the present invention, the trigger force may be generated by the penetration of water into the paper-containing structure, a change in humidity in the environment in which the paper-containing structure is placed, localized compression of the paper-containing structure, heating of the paper-containing structure, cooling of the paper-containing structure, cutting of a part of the paper-containing structure, or application of an external force from another direction to the paper-containing structure. This also applies to the following embodiments.

[0058] 13 to 15 show a paper-containing structure 30, which is a second embodiment of the paper-containing structure of the present invention. In this paper-containing structure 30, a first hydroxyl group high concentration region 11, which is a band extending in the short side direction, is formed in the widthwise center of the first surface 1a of a rectangular paper-containing sheet 2 by printing with water or an aqueous solution, or the like. On the second surface 1b of the paper-containing sheet 2, as shown in FIG. 14, a second hydroxyl group high concentration region 14, which is a band extending in the V-shape in plan view from both corners of one short side toward the center of the other short side, is formed by printing with water or an aqueous solution, or the like. The paper-containing sheet 2 is then sufficiently dried.

[0059] In this paper-containing structure 30, a mountain fold line 5 is formed in advance along the center in the width direction of the second hydroxyl group high concentration region 14. In addition, a valley fold line 6 is formed once along the center in the width direction of the first hydroxyl group high concentration region 11 and then stretched flat. In this state, the valley fold line 6 is almost invisible.

[0060] After the drying process, the paper-containing sheet 2 is bent in a V-shape at the mountain fold line 5 so that both ends are concave toward the second surface 1b along the second hydroxyl group high concentration region 14 due to tensile stress that tends to shrink the sheet in the width direction within the second hydroxyl group high concentration region 14. Meanwhile, tensile stress that tends to shrink the sheet in the width direction of the first hydroxyl group high concentration region 11 also occurs within the first hydroxyl group high concentration region 11, but because the paper-containing sheet 2 is first bent in a V-shape at the mountain fold line 5, the resistance to deformation against the force bending the paper-containing sheet 2 along the long side direction is high, and almost no deformation due to the tensile stress of the second hydroxyl group high concentration region 14 occurs. As a result, as shown in Figure 13, the mountain fold lines 5, which are arranged in a V-shape when viewed from above, are stable in a first shape bent in a V-shape in cross section.

[0061] Next, by applying a downward force to the center of the first surface 1a of the paper-containing structure 20, which is stable in the first shape shown in Figure 13, the paper-containing sheet 2 bends at the hidden valley fold line 6, as shown in Figure 15, and the mountain fold line 5 is bent in the center. As a result, the anti-deformation force of the mountain fold line 5 weakens, and the tensile stress of the first hydroxyl group high concentration region 11 prevails, causing the paper-containing sheet 2 to deform into a V-shaped cross section concave toward the first surface 1a. The paper-containing sheet then stops, maintaining the second shape shown in Figure 15. In the second shape shown in Figure 15, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, preventing further deformation.

[0062] Therefore, with this paper-containing structure 30, when the first shape shown in Fig. 13 is applied with a downward force to the center of the first surface 1a, it can easily change to the second shape shown in Fig. 15, and in the process can perform various functions. For example, by forming a V-shape in the second shape, the paper-containing structure 30 can hold other items, perform switching operations, or press other items by increasing the thickness of the paper-containing structure 30. The cross sections of the mountain fold line 5 and the valley fold line 6 may be gently curved in a U-shape rather than being V-shaped as shown in the figure.

[0063] For ease of explanation, the long and short sides of the paper-containing sheet 2 in the paper-containing structure 30 have been described above, but the long and short sides may be reversed, or the paper-containing sheet 2 may be square, or the paper-containing sheet 2 may be any shape such as circular, elliptical, triangular, pentagonal, or irregular. The shapes of the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 do not have to be linear bands, but may be curved, or the width of the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 may change in the longitudinal direction.

[0064] 16, 17A, and 17B show a paper-containing structure 40, which is a third embodiment of the paper-containing structure of the present invention. In this paper-containing structure 40, a band-shaped first hydroxyl group high concentration region 11 extending in the short side direction is formed on the first surface 1a of a rectangular paper-containing sheet 2 by printing with water or an aqueous solution, etc. Furthermore, a semicircular or semi-elliptical band-shaped second hydroxyl group high concentration region 14 connecting both ends of each long side and passing near the center of the paper-containing sheet 2 is formed on the second surface 1b of the paper-containing sheet 2 by printing with water or an aqueous solution, etc. The paper-containing sheet 2 is then sufficiently dried.

[0065] In this paper-containing structure 40, mountain fold lines 5, each curved in cross section with a small radius of curvature, are formed in advance along the second hydroxyl group-rich region 14 by press processing using a mold or similar. However, this press processing is not required in the present invention; the structure can operate even when the material is applied and dried. Furthermore, valley fold lines 6 are formed once along the center of the width of the first hydroxyl group-rich region 11 and then flattened. In this state, the valley fold lines 6 are almost invisible. Although folds may occur depending on the type of printing machine or printing sequence, their high resistance to deformation prevents bending, allowing the structure to form a flat state without having to be flattened again after printing. In this case, the flattening process is unnecessary. Whether the structure remains flat or a fold is formed after printing is affected by the design (thickness, curvature, etc.) of the printing lines on the first surface 1a and second surface 1b of the paper-containing sheet 2, and should be individually set. This also applies to the following embodiments.

[0066] After the drying process, the paper-containing sheet 2 is curved with a small curvature around the mountain fold line 5 due to tensile stress that tends to shrink the sheet in the width direction within the second hydroxyl group high concentration region 14, which applies a force to the mountain fold line 5 in a direction that further reduces the radius of curvature. Meanwhile, tensile stress that tends to shrink the sheet in the width direction of the first hydroxyl group high concentration region 11 also occurs within the first hydroxyl group high concentration region 11, but because the paper-containing sheet 2 has already curved along the semicircular or semicircular arc-shaped mountain fold line 5, the resistance of the paper-containing sheet 2 to deformation against the force bending the sheet in the long side direction is high, and no deformation occurs due to the tensile stress of the second hydroxyl group high concentration region 14. As a result, the mountain fold lines 5 shown in Figure 13 each protrude toward the first surface 1a as shown in Figure 17A, and the paper-containing sheet 2 is stabilized in a dome-shaped first shape with a raised center.

[0067] Next, by applying a downward force to the center of the first surface 1a of the paper-containing structure 40, which is stable in the first shape shown in Figure 16, the paper-containing sheet 2 bends at the hidden valley fold line 6 as a boundary, as shown in Figures 17A and 17B, the mountain fold line 5 is bent at the center, the anti-deformation force due to the mountain fold line 5 is weakened, the tensile stress due to the first hydroxyl group high concentration region 11 prevails, and the paper-containing sheet 2 deforms concavely toward the first surface 1a (curves upward).The paper-containing sheet then stops, maintaining the second shape shown in Figure 17B.In ​​the second shape, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, so no further deformation occurs.

[0068] Therefore, with this paper-containing structure 40, when the first shape shown in Fig. 16 is applied with a downward force to the center of the first surface 1a, it changes to the second shape shown in Fig. 17B, and in the process can perform various functions. For example, when the paper-containing structure 40 is in the second shape, it has a V-shape, which makes it possible to pinch other items, perform switching operations, and lower other items by reducing the dome height of the paper-containing structure 30.

[0069] For convenience of explanation, the long and short sides of the paper-containing sheet 2 in the paper-containing structure 40 have been described above, but the long and short sides may be reversed, or the paper-containing sheet 2 may be square, or the paper-containing sheet 2 may be any shape such as circular, elliptical, triangular, pentagonal, irregular, etc. The width of the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 may vary in the longitudinal direction.

[0070] FIG. 18 shows a test piece for verifying the effects of the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 of the third embodiment. The first hydroxyl group-rich region 11, which is a strip extending along the short side, is formed on the first surface 1a of the rectangular paper-containing sheet 2 by printing with water or an aqueous solution, or the like. The first hydroxyl group-rich region 14, which is a semicircular or semi-elliptical strip connecting both ends of each long side and passing near the center of the paper-containing sheet 2, is formed on the second surface 1b of the paper-containing sheet 2 by printing with water or an aqueous solution, or the like. A crest line 5 curved with a small radius of curvature is formed in advance along the widthwise center of the second hydroxyl group-rich region 14 by press processing using a mold, or the like. The paper-containing sheet 2 is then sufficiently dried. A valley line 6 is formed along the widthwise center of the first hydroxyl group-rich region 11 and then flattened. In this state, the valley line 6 is almost invisible. Even in this embodiment, if the surface is flat after printing, further pressing is not necessary.

[0071] The length r1 of the perpendicular line from the center of the second hydroxyl group high concentration region 14 to the long side of the paper-containing sheet 2 was 24 mm, and the length r2 of half the long side of the paper-containing sheet 2 was 15 mm. The paper-containing sheet 2 was commercially available tracing paper, and its thickness was 39.5 kg, 56.0 kg, and 88.0 kg in terms of the ream weight (1000 sheets) of 46-size paper. The width of the second hydroxyl group high concentration region 14 was 2 mm.

[0072] First, a commercially available tracing paper with a ream weight (1000 sheets) of 46-size paper and a weight of 56.0 kg was used, and the narrowest width W of the two second hydroxyl group high concentration regions 14 was changed to 10, 20, 30, and 40 mm, respectively, to produce paper-containing structures 50. These paper-containing structures 50 had a dome-shaped first shape. The center P of each of these dome-shaped paper-containing sheets 2 was pressed down with a measuring device, and the change in the pressing force was recorded. The results were as shown in the graph in FIG. 19.

[0073] As shown in Figure 19, when the distance between the curves was 30 mm, a larger peak appeared than when the distance was 10, 20, or 40 mm, and the load peaked when the displacement (push-down distance) was 12.5 mm. Once the displacement passed this peak, the load suddenly decreased, indicating that the dome shape was crushed and displaced to the second shape. In this way, by adjusting the geometric shape of the second hydroxyl group-rich region 14, it was possible to variably adjust the operating point of the paper-containing structure 50 and the trigger force leading to the shape change.

[0074] 20 shows the results of the test piece of FIG. 18 in which the thickness of the tracing paper serving as the paper-containing sheet 2 was changed to 39.5 kg, 56.0 kg, and 88.0 kg in a ream weight (1,000 sheets) of 46-size paper, and the narrowest width W of the two second hydroxyl group high concentration regions 14 was set to 10 mm, the length r1 to 24 mm, and the length r2 to 15 mm. Then, while gradually applying a load, the cross-sectional angle sandwiching the first hydroxyl group high concentration region 11 before and after the morphological change was measured.

[0075] As shown in FIG. 20, when the ream weight was 39.5 kg and 56.0 kg, a large angle change was obtained, but when the ream weight was 88.0 kg, the paper-containing sheet 2 was too thick and an appropriate angle change was not obtained.

[0076] Next, Figure 21 shows the results of measuring the cross-sectional angle sandwiching the first hydroxyl group high concentration region 11 when the printing width of the first hydroxyl group high concentration region 11 was changed to 6, 8, and 10 mm in the test piece of Figure 18. The narrowest width W of the two second hydroxyl group high concentration regions 14 was 10 mm, the length r1 was 24 mm, and the length r2 was 15 mm. Then, the cross-sectional angle sandwiching the first hydroxyl group high concentration region 11 was measured while gradually applying a load.

[0077] 21, the angle change increased as the printing width of the first hydroxyl group high concentration region 11 increased to 6, 8, and 10 mm. This proves that the tensile stress generated by the first hydroxyl group high concentration region 11 increases as the width of the first hydroxyl group high concentration region 11 increases.

[0078] 22 and 23 show a paper-containing structure 60 according to a fourth embodiment of the present invention. In this paper-containing structure 60, a circular opening 61 is formed in the center of a square paper-containing sheet 2. On the first surface 1a of the paper-containing sheet 2, band-shaped first hydroxyl group-rich regions 11 are formed by printing with water or an aqueous solution, or the like, radially from the opening 61 along the diagonal of the paper-containing sheet 2. On the second surface 1b of the paper-containing sheet 2, band-shaped second hydroxyl group-rich regions 14 are formed by printing with water or an aqueous solution, radially from the opening 61, reaching the center of each side of the paper-containing sheet 2. The paper-containing sheet 2 is then sufficiently dried, optionally with a press or the like, to curve into a spherical shape. The widths of the first hydroxyl group-rich regions 11 and the second hydroxyl group-rich regions 14 increase toward the outside. The openings 61 are formed at locations where folding lines converge on the paper-containing sheet 2, allowing each folding line to bend appropriately.

[0079] After the drying process, the paper-containing sheet 2 experiences tensile stress within the second hydroxyl group high concentration region 14, which tends to shrink the sheet in the width direction. Tensile stress also occurs within the first hydroxyl group high concentration region 11, which tends to shrink the sheet in the width direction. However, because the paper-containing sheet 2 is pressed to curve as a whole, the resistance to deformation against the force bending the paper-containing sheet 2 along the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 is high, and almost no deformation occurs due to the tensile stress in the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14. As a result, the paper-containing sheet 2 remains stable in the curved first shape as a whole, as shown in FIG.

[0080] Next, by applying a downward force to the center of the first surface 1a of the paper-containing structure 60, which is stable in the first shape shown in Figure 23, the curved shape of the paper-containing sheet 2 approaches flattening, the resistance to deformation of the paper-containing sheet 2 weakens, and the tensile stress due to the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 prevail, causing the paper-containing sheet 2 to deform concavely toward the first surface 1a along the first hydroxyl group high concentration region 11 and concavely toward the first surface 1a along the second hydroxyl group high concentration region 14. As a result, the paper-containing sheet 2 remains in the second shape shown in Figure 22, which is a cross-star shape when viewed from above and a triangular shape when viewed from the front. In the second shape, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the resistance to deformation of the paper-containing sheet 2 are balanced, so no further deformation occurs.

[0081] Therefore, with this paper-containing structure 60, when a downward force is applied to the center of the first surface 1a in the convex curved first shape shown in Fig. 23, it changes to the second shape shown in Fig. 22, and in the process can perform various functions. For example, when the paper-containing structure 60 forms a mountain shape in the second shape, it can hold other items, perform switching operations, or raise other items by increasing the dome height of the paper-containing structure 60.

[0082] Instead of curving the paper-containing sheet 2, a ring-shaped protrusion 62 may be formed in the center of the paper-containing sheet 2, coaxial with the opening 61. The cross section of the ring-shaped protrusion 62 is curved convexly. The ring-shaped protrusion 62 increases the resistance to deformation against the force that bends the paper-containing sheet 2 along the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14, and deformation due to tensile stress in the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 is almost eliminated. As a result, the paper-containing sheet 2 is stabilized in a flat first shape as a whole, as shown in Figure 23. Meanwhile, by pressing down on the center of the paper-containing sheet 2, the ring-shaped convex portion 62 becomes flatter, weakening the anti-deformation force of the paper-containing sheet 2. The tensile stresses from the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 prevail, causing the paper-containing sheet 2 to deform concavely toward the first surface 1a along the first hydroxyl group high concentration region 11 and concavely toward the first surface 1a along the second hydroxyl group high concentration region 14. As a result, the paper-containing sheet 2 remains in the second shape shown in Figure 22, which is a cross star when viewed from above and a triangular shape when viewed from the front. In this case, the tensile stresses generated by the first hydroxyl group high concentration region 11, the tensile stresses of the second hydroxyl group high concentration region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, preventing further deformation.

[0083] 24 to 29 show a drone gripping device (paper-containing structure) 70 according to a fifth embodiment of the present invention. The gripping device of the present invention is not limited to drones, but can be applied to any object that can be attached to a moving object and used to grip the target object. For example, it can be attached to a robot, the tip of a robot arm, a small, self-propelled machine, a living organism such as an insect, or the human body. The gripping direction can be set according to the position of the object to be gripped, and can be the bottom edge, side edge, or top edge of the paper-containing sheet.

[0084] As shown in Figures 28 and 29, the drone gripping device 70 is attached to a support 75 at the bottom of a flying drone 74, and is used to grasp and lift a target object 77 by placing it over the object 77. The drone gripping device 70 automatically closes to grasp and lift the object 77. The method of attachment of the drone gripping device 70 is not limited to the downward-facing state shown in the figure. For example, the drone gripping device 70 may be attached to the side of the drone 74 facing laterally to grasp an object located to the side, or may be attached to the top of the drone 74 facing upward to grasp an object located above the drone 74. The drone gripping device of the present invention can also change from the second shape to the first shape to grasp an object to a destination point, and then release the object from the drone at the destination point and drop or place it.

[0085] 24 and 25, the paper-containing sheet 2 of this drone gripping device 70 has a generally H-shaped configuration with rectangular roll deformation portions 71 formed on both sides of the two long sides of the rectangular main body in the longitudinal direction. Gaps 72 are formed between the roll deformation portions 71.

[0086] As shown in Fig. 24, four first high hydroxyl concentration regions 11 are formed on the first surface 1a of the paper-containing sheet 2 radially from the opening 73 toward each roll deformation portion 71. Also, as shown in Fig. 25, a large number of second high hydroxyl concentration regions 14 are formed on the second surface 1b of the paper-containing sheet 2 at the positions shown by printing with water or an aqueous solution. Specifically, these are band-shaped second high hydroxyl concentration regions 14 extending from the opening 73 to each gap 72, band-shaped second high hydroxyl concentration regions 14 extending from the opening 73 along both sides of the mountain fold line 5 formed in the center of the paper-containing sheet 2, second high hydroxyl concentration regions 14 formed over the entire surface of the roll deformation portion 71, and second high hydroxyl concentration regions 14 adjacent to the roll deformation portion 71. Then, as shown in Fig. 28, the paper-containing sheet 2 is curved and thoroughly dried so that the first surface 1a is concave overall. The roll deformation portion 71 is already rolled into a cylindrical shape in the initial state due to the tensile stress of the second hydroxyl group high concentration region 14. This roll deformation portion 71 is formed to sufficiently increase the strength of the contact point with the article 77 when gripping the article 77.

[0087] The drone gripping device 70 is fixed to a support 75 of the drone 74 through the opening 73 and is suspended from the drone 74. In this state, the opening 73 is bent upward and the roll deformation portion 71 is open. This state is the first shape.

[0088] Next, the drone gripping device 70, which is stable in the first shape shown in Fig. 28 , is lowered by the drone 74 so that it abuts against the item 77. When it collides with the item 77, the center of the drone gripping device 70 is lifted, becomes convex upward, and is inverted as shown in Fig. 29. As a result, the drone gripping device 70 covers the item 77, and the roll deformation portion 71 abuts against and supports the lower end of the item 77, so that the item 77 can be lifted by raising the drone 74.

[0089] That is, by applying a force to lift the second surface 1b to the paper-containing sheet 2, the paper-containing sheet 2 is inverted downward, weakening the anti-deformation force of the paper-containing sheet 2. The tensile stresses from the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 prevail, causing the paper-containing sheet 2 to deform concavely toward the first surface 1a along the first hydroxyl group-rich region 11 and concavely toward the second surface 1b along the second hydroxyl group-rich region 14. As a result, the paper-containing sheet 2 remains in the second shape, which is a three-dimensional shape with a narrowed bottom, as shown in Figures 26 and 27. In the second shape, the tensile stresses generated by the first hydroxyl group-rich region 11, the tensile stresses of the second hydroxyl group-rich region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, preventing further deformation. When supporting the item 77, the anti-deformation force from the item 77 is also applied, so the sheet does not narrow to the state shown in Figure 26, but rather the item 77 is sandwiched and compressed.

[0090] Therefore, with this drone gripper 70, when a pushing force is applied to the center of the second surface 1b in the upwardly curved first shape shown in Figure 28, it changes to the downwardly narrowed second shape shown in Figure 29, and in the process, it can perform the function of gripping an item 77. In this way, the drone gripper 70 automatically closes and grips the item 77 simply by raising and lowering the drone 74, so an automatic gripping device can be realized at low cost without complicating the structure of the drone 74. When the roll deformation portion 71 is lifted from the state in which the item 77 is gripped, the device curls up again to the state shown in Figure 28, making it easy to release the item 77. The item 77 can be used for a variety of purposes, such as agricultural products such as fruit, medicine, mail, and food in food processing.

[0091] Sixth Embodiment Figures 30 to 32 show a cushioning material 80 having a honeycomb structure, a sixth embodiment of the present invention. The honeycomb structure has attractive structural characteristics, including high porosity and light weight. The air layer within the hexagonal cells of the honeycomb structure prevents convection and provides excellent thermal buffering, i.e., thermal insulation. Furthermore, in the event of an impact, the energy is dispersed to the adjacent surfaces, providing excellent shock absorption. The cushioning material of the present invention can also be widely used as a core material for sandwich structures, sandwiched between panels on both sides. Small holes can be drilled in the flat panel on one side of the sandwich structure to allow sound to resonate within the honeycomb, thereby achieving a sound-deadening effect. Therefore, the cushioning material of the present invention can be used in a variety of applications as a highly functional cushioning material. In addition to the honeycomb structure, the cylindrical wall shape of the present invention can also be triangular, rectangular, or pentagonal. The cushioning material of the present invention can also be used as a support for temporarily parking drones, a support used to install sensors at high altitudes, and a container or support for collecting items or belongings at disaster or accident sites.

[0092] A cushioning material 80 having a honeycomb structure has a three-dimensional shape in its second shape, which is its mode of use, having one or more openings 81, a cylindrical wall portion 82 standing around the openings 81, and a support portion 83 extending from the cylindrical wall portion 82, as shown in Fig. 32. When not in use, the cushioning material 80 takes on a flat first shape, as shown in Figs. 30 and 31. The flat first shape has the advantage that multiple cushioning materials 80 can be stacked for storage, and when unfolded, an item can be placed in the opening 81 of the cylindrical wall portion 82, and the cylindrical wall portion 82 and support portion 83 form the cushioning material 80 that protects the item from forces in the vertical and horizontal directions.

[0093] As shown in FIGS. 30 and 31, the paper-containing sheet 2 of the cushioning material 80 has a long, narrow rectangular shape, and rectangular openings 81 are formed at intervals in the center in the width direction.

[0094] As shown in Fig. 30, nine first hydroxyl group high concentration regions 11 are formed on the first surface 1a of the paper-containing sheet 2 by printing with water or an aqueous solution or the like so as to extend from each opening 81. Also, as shown in Fig. 31, many second hydroxyl group high concentration regions 14 are formed on the second surface 1b of the paper-containing sheet 2 at the positions shown in the figure by printing with water or an aqueous solution or the like.

[0095] Specifically, as shown in Figure 30, the first hydroxyl group high concentration region 11 includes a thin first hydroxyl group high concentration region 11 extending from a position dividing the long side of the opening 81 into three equal parts along the foot of the perpendicular to the long side of the paper-containing sheet 2, a relatively thick first hydroxyl group high concentration region 11 connecting the short sides of the opening 81, and a relatively thick first hydroxyl group high concentration region 11 extending from the short side of the opening 81 to the center of the short side of the paper-containing sheet 2.

[0096] As shown in Figure 31, the second hydroxyl group high concentration regions 14 include thin second hydroxyl group high concentration regions 14 extending along the feet of perpendicular lines from both ends of the long side of the opening 81 to the long side of the paper-containing sheet 2, thin semicircular second hydroxyl group high concentration regions 14 arranged to surround both ends of the long side of the opening 81, and thin semicircular second hydroxyl group high concentration regions 14 arranged to surround the center of each short side of the paper-containing sheet 2.

[0097] This buffer material 80 is prepared by forming the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 by printing or the like, and then pressing the paper-containing sheet 2 into a flat plate, if necessary, and then stacking the buffer material 80 on top of it for storage. If the flatness can be maintained after the printing has dried, pressing is not necessary. In this state, the tensile stress of the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 is counterbalanced by the anti-deformation force of the paper-containing sheet 2 because the buffer material 80 is stacked on top of it, so the flat first shape is maintained.

[0098] When the buffer material 80 is removed and a trigger force, which is a mechanical stimulus, is applied to the buffer material 80, the anti-deformation force of the paper-containing sheet 2 weakens, and the tensile stress due to the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 prevail, causing the paper-containing sheet 2 to deform, becoming concave toward the first surface 1a along the first hydroxyl group high concentration region 11 and concave toward the first surface 1a along the second hydroxyl group high concentration region 14. As a result, the buffer material 80 changes to a second shape as shown in Figure 32 and stops. In the second shape, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, so no further deformation occurs.

[0099] This cushioning material 80 has the advantage that in the flat first shape, many cushioning materials 80 can be stacked for storage, and when a trigger force is applied to cause it to deform, an item can be stored in the opening 81 of the tubular wall portion 82, and the tubular wall portion 82 and the support portion 83 become cushioning material 80 that protects the item from forces from the vertical and horizontal directions, so that cushioning material 80 with sufficient cushioning power can be obtained at low cost. Because no plastic is used, it is also environmentally friendly.

[0100] Seventh Embodiment FIGS. 33 to 36 show a cushioning material 90 according to a seventh embodiment of the present invention. The cushioning material 90 has a structure in which the cushioning material 80 of the sixth embodiment is connected in the width direction. In the second shape, which is the usage mode of the cushioning material 90, as shown in FIG. 36, the cushioning material 90 has a three-dimensional shape having four openings 91, cylindrical wall portions 92 standing around the openings 91, and support portions 93 extending from the cylindrical wall portions 92. The cylindrical wall portions 92 are connected to each other by the support portions 93. When not in use, the cushioning material 90 takes a flat first shape as shown in FIGS. 33 and 34. The flat first shape has the advantage that multiple cushioning materials 90 can be stacked and stored. When unfolded, items can be placed in the openings 91 of the cylindrical wall portions 92, and the cylindrical wall portions 92 and support portions 93 form the cushioning material 90 to protect the items from forces in the vertical and horizontal directions.

[0101] As shown in FIGS. 33 and 34, the paper-containing sheet 2 of the cushioning material 90 is rectangular, and has rectangular openings 91 formed in three rows spaced apart from one another.

[0102] As shown in Fig. 33, first hydroxyl group high concentration regions 11 are formed on the first surface 1a of the paper-containing sheet 2 by printing with water or an aqueous solution or the like so as to extend from each opening 91. Also, as shown in Fig. 34, a large number of second hydroxyl group high concentration regions 14 are formed on the second surface 1b of the paper-containing sheet 2 at the positions shown in the figure by printing with water or an aqueous solution or the like.

[0103] Specifically, as shown in Figure 33, the first hydroxyl group high concentration region 11 includes a thin first hydroxyl group high concentration region 11 extending from a position dividing the long side of the opening 91 into three equal parts, a relatively thick first hydroxyl group high concentration region 11 connecting the short sides of the opening 91, a relatively thick first hydroxyl group high concentration region 11 extending from the short side of the opening 91 to the center of the short side of the paper-containing sheet 2, and a semicircular first hydroxyl group high concentration region 11 arranged to surround the short side of the opening 91 in the center.

[0104] As shown in Figure 34, the second hydroxyl group high concentration regions 14 include thin second hydroxyl group high concentration regions 14 extending along the feet of perpendicular lines from both ends of the long side of the opening 91 to the long side of the paper-containing sheet 2, thin semicircular second hydroxyl group high concentration regions 14 arranged to surround both ends of the long side of the openings 91 on both sides, and thin semicircular second hydroxyl group high concentration regions 14 centered on each short side of the paper-containing sheet 2.

[0105] This buffer material 90 is prepared by forming the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 by printing or the like, and then, if necessary, pressing the paper-containing sheet 2 into a flat plate shape, with the buffer material 90 superimposed on top, and then storing the paper-containing sheet 2. If the flatness can be maintained after the printing has dried, pressing is not necessary. In this state, the tensile stress of the first hydroxyl group-rich region 11 and the second hydroxyl group-rich region 14 is counterbalanced by the anti-deformation force of the paper-containing sheet 2 because the buffer material 90 is superimposed, thereby maintaining the flat first shape.

[0106] When the buffer material 90 is removed and a trigger force, which is a mechanical stimulus, is applied to the buffer material 90, the anti-deformation force of the paper-containing sheet 2 weakens, and the tensile stress due to the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 prevail, causing the paper-containing sheet 2 to deform, becoming concave toward the first surface 1a along the first hydroxyl group high concentration region 11 and concave toward the first surface 1a along the second hydroxyl group high concentration region 14. As a result, the buffer material 90 changes to and stops in the second shape as shown in Figures 35 and 36. In the second shape, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, so no further deformation occurs.

[0107] This cushioning material 90 has the advantage that in the flat first shape, many cushioning materials 90 can be stacked for storage, and when a trigger force is applied to cause it to deform, items can be stored in the openings 91 of many of the tubular wall portions 92, and the tubular wall portions 92 and support portions 93 become cushioning materials 90 that protect items from forces from the top, bottom, and left and right directions, so that cushioning material 90 with sufficient cushioning power can be obtained at low cost. Because no plastic is used, it is also environmentally friendly.

[0108] Eighth Embodiment Figures 37 to 39 show a cushioning material 100 according to an eighth embodiment of the present invention. In the second shape, which is the usage mode of this cushioning material 100, as shown in Figure 39, the cushioning material 100 has a three-dimensional shape with staggered square openings 101 and undulations 102 connecting the openings 101 to each other. The undulating portions 102 have alternating mountain and valley fold lines. When not in use, the cushioning material 100 takes the flat first shape, as shown in Figures 38 and 39. The flat first shape has the advantage that multiple cushioning materials 100 can be stacked and stored. When unfolded, items can be stored in the valley portions of the undulating portions 102, and the undulating portions 102 form the cushioning material 100 that protects the items from forces in the vertical and horizontal directions.

[0109] As shown in Figure 37, first hydroxyl group high concentration regions 11 are formed on the first surface 1a of the paper-containing sheet 2 by printing with water or an aqueous solution or the like so as to extend from each opening 101. Also, as shown in Figure 38, multiple second hydroxyl group high concentration regions 14 are formed on the second surface 1b of the paper-containing sheet 2 at the positions shown in the figure by printing with water or an aqueous solution or the like. The first hydroxyl group high concentration regions 11 and the second hydroxyl group high concentration regions 14 form a so-called Miura fold pattern.

[0110] This buffer material 100 is stored by forming the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 by printing or the like, pressing the paper-containing sheet 2 into a flat plate, and then stacking the buffer material 100 on top of it. In this state, the tensile stress of the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 is counterbalanced by the anti-deformation force of the paper-containing sheet 2 because the buffer material 100 is stacked on top of it, so the first flat shape is maintained.

[0111] When the cushioning material 100 is removed and a trigger force, which is a mechanical stimulus, is applied to the cushioning material 100, the anti-deformation force of the paper-containing sheet 2 weakens, and the tensile stress due to the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 prevail, causing the paper-containing sheet 2 to deform, becoming concave toward the first surface 1a along the first hydroxyl group high concentration region 11 and concave toward the first surface 1a along the second hydroxyl group high concentration region 14. As a result, the cushioning material 100 changes to a second shape having a Miura fold structure as shown in Figure 39 and stops. In the second shape, the tensile stress generated by the first hydroxyl group high concentration region 11, the tensile stress of the second hydroxyl group high concentration region 14, and the anti-deformation force of the paper-containing sheet 2 are balanced, so no further deformation occurs.

[0112] This cushioning material 100 has the advantage that in the flat first shape, many cushioning materials 100 can be stacked for storage, and when a trigger force is applied to cause it to deform, an item can be stored in the valleys between the undulating portions 102, and the cylindrical wall portion 102 and the support portion 103 become cushioning material 100 that protects the item from forces from the up and down and left and right directions, so that cushioning material 100 with sufficient cushioning power can be obtained at low cost. Because no plastic is used, it is also environmentally friendly.

[0113] Figure 40 shows an embodiment in which the Miura fold structure is further expanded. Another pattern may be a so-called egg box shape, as shown in Figure 41.

[0114] 42 is an enlarged cross-sectional view showing a ninth embodiment of a paper-containing structure 1 according to the present invention. This ninth embodiment is characterized in that a protective film 104 is fixed over the entire surface of each of the first surface 1a and the second surface 1b of a paper-containing sheet 2 on which first hydroxyl group high concentration regions 11 and second hydroxyl group high concentration regions 14 are formed in various patterns, via an adhesive layer 103. The paper-containing sheet 2 may be any of the paper-containing sheets 2 described in this specification.

[0115] By sandwiching the paper-containing sheet 2 between the protective films 104 in this manner, even if the paper-containing structure 1 is wet or placed in a humid environment, unnecessary moisture will not penetrate the paper-containing sheet 2, and the deformation function of the paper-containing sheet 2 due to the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 can be maintained. Furthermore, when the paper-containing structure 1 is used to hold a moisture-rich item such as fruit, the paper-containing structure 1 can be prevented from absorbing moisture from the item. Therefore, the freshness of the fruit or the like can be maintained. Furthermore, by covering the surface with the protective film 104, the coefficient of friction of the surface that comes into contact with the item, such as fruit, is increased, thereby improving the stability of the item when stored.

[0116] The protective film 104 is preferably made of various plastics with excellent moisture resistance, and although the material is not limited, examples include polyethylenes such as linear short-chain branched polyethylene (LLDPE) and low-density polyethylene (LDPE), polyolefin resins such as unoriented polypropylene (CPP), polyvinyl acetate resins, polyvinyl chloride resins, poly(meth)acrylic resins, urethane resins, etc. The thickness of the protective film 104 is not limited, but is preferably 0.001 μm or more and 10,000 μm or less, and more preferably 0.01 μm or more and 100 μm or less, so as to maintain appropriate moisture resistance and not inhibit deformation of the paper-containing sheet 2. Furthermore, from the viewpoint of preventing the protective film 104 from interfering with the deformation of the paper-containing sheet 2 as little as possible, it is preferable that the thickness of the paper-containing sheet 2 be 0.01 μm or more and 10,000 μm or less, more preferably 1 μm or more and 1,000 μm or less, and the thickness of the protective film 104 be approximately 0.001% or more and 1,000% or less, more preferably 1% or more and 100% or less of the thickness of the paper-containing sheet 2.

[0117] The adhesive layer 103 can be, for example, a one-component or two-component cured or non-cured vinyl adhesive layer, a (meth)acrylic adhesive layer, a polyamide adhesive layer, a polyester adhesive layer, a polyether adhesive layer, a polyurethane adhesive layer, an epoxy adhesive layer, a rubber adhesive layer, or other solvent-based adhesive layer, a water-based adhesive layer, an emulsion-based adhesive layer, etc. When dry lamination is performed, an adhesive diluted with an organic solvent is coated on the protective film 104, and after drying, the paper-containing sheet 2, on which the first hydroxyl group high concentration region 11 and the second hydroxyl group high concentration region 14 have been formed in advance, is sandwiched between a pair of protective films 104 and pressed together with heated rolls to bond them together.

[0118] 42, in the paper-containing structure 1, the ends of the protective films 104 on both sides may extend over the edge of the paper-containing sheet 2 to form edge protective films 105, and the edge of the paper-containing sheet 2 may be airtightly sealed by the plastic that makes up the protective films 104. When the paper-containing structure 1, in which the protective films 104 are bonded to both sides of the paper-containing sheet 2 via adhesive layers 103, is cut with a laser beam using a laser cutter or the like, the protective films 104 (and adhesive layers 103) melt at high temperature and flow along the edge of the paper-containing sheet 2, forming edge protective films 105 that airtightly cover the edge of the paper-containing sheet 2, thereby easily forming the edge sealing structure of FIG. 42. However, the paper-containing structure 1 of the ninth embodiment may also be configured without the edge protective films 105.

[0119] [Tenth Embodiment] In the ninth embodiment, protective films 104 were provided on both sides of the paper-containing sheet 2. However, as shown in FIG. 43, the protective film 104 may be provided on only one side of the paper-containing sheet 2 via an adhesive layer 103. In applications where water droplets fall on only one side of the paper-containing sheet 2, it is not a problem if the second side 1b of the paper-containing sheet 2 is exposed. Furthermore, in the ninth and tenth embodiments, instead of providing the protective film 104 on the entire surface of the paper-containing sheet 2, the protective film 104 may be formed in a certain pattern only in necessary areas via an adhesive layer 103. These necessary areas include areas that come into contact with moisture or liquids such as water, or areas that come into contact with fruit or other moisture-rich items. Furthermore, if the material of the protective film 104 is suitable, it is also possible to directly heat-soften the protective film 104, attach it to the paper-containing sheet 2, and heat-seal it, without providing the adhesive layer 103.

[0120] 44 is an enlarged cross-sectional view showing an eleventh embodiment of the present invention. In this eleventh embodiment, protective films 104 are attached via adhesive layers 103 to both sides of a paper-containing sheet 2 on which first high hydroxyl group concentration regions 11 and second high hydroxyl group concentration regions 14 have been formed. A nonwoven fabric 107 is then attached to the entire surface of one of the protective films 104 via an adhesive layer 106. The pair of protective films 104 protects the paper-containing sheet 2 from moisture and maintains the deformability of the paper-containing sheet 2, while the nonwoven fabric 107 softens the contact surface with the article, protecting the article and absorbing excess moisture from the article. The nonwoven fabric 107 may have a specific pattern depending on the purpose.

[0121] 45 is an enlarged cross-sectional view showing a twelfth embodiment of the present invention. In this twelfth embodiment, a paper-containing sheet 2 is preliminarily formed with a first high hydroxyl group concentration region 11 and a second high hydroxyl group concentration region 14. Protective films 104 are attached to both sides of the sheet via adhesive layers 103. A circuit layer 108 is provided on one of the protective films 104, and is then covered with a protective film 109.

[0122] The circuit layer 108 may have a circuit made of a thin metal film with high conductivity such as copper or aluminum, forming a fixed pattern, and sensors, resistors, capacitors, integrated circuits, coils, antennas, etc. arranged on the circuit, and in combination with the deformability of the paper-containing sheet 2, it performs necessary functions such as sensing, signal processing, and communication.

[0123] 46 is a plan view showing a sensing pad 110 as a twelfth embodiment of the present invention. The sensing pad 110 has a three-dimensional shape that fits to a specific part of a living body such as a human or animal, and has a number of sensors 111 that detect electrical signals, temperature, electrical conductivity, and the concentration of specific substances from the living body using the sensors 111, process the signals, and send them to the outside via cables 112. Protective films 104 may be formed on both sides of the paper-containing sheet 2 via adhesive layers 103, or a type without protective films 104 may be used.

[0124] The shape of the sensing pad 110 is not limited, but the illustrated example is cross-shaped, with a first hydroxyl group-rich region 11 that forms a V-shape in plan view toward the center of the tips of four extensions extending from the center, and a second hydroxyl group-rich region 14 that crosses the first hydroxyl group-rich region 11 at the base of the extensions. Due to the action of these first hydroxyl group-rich region 11 and second hydroxyl group-rich region 14, when triggered by a trigger force, the back surface of the sensing pad 110 can be deformed into a gently concave curve, allowing it to be placed on, for example, a human head 113 with almost no gaps. Multiple sensors 111 are arranged on the back surface of the sensing pad 110 and are connected to a central cable 112 via an electronic circuit (not shown). When the sensing pad 110 is placed along the curved surface of the head 113, all of the sensors 111 abut against the surface of the head 113, detecting an electrical signal and transmitting it via the cable 112. This allows electrical signals to be detected at multiple points on the head 113 and used for, for example, brain diagnosis and analysis.

[0125] 48 and 49 are partially cutaway plan and cross-sectional views showing an absorbent pad 120 for use as a sanitary napkin or the like, as a thirteenth embodiment of the present invention. As shown in Fig. 48, this absorbent pad 120 has, for example, a rectangular shape with rounded corners. As shown in Fig. 49, it has a support 122 including a paper-containing sheet 2 and an absorbent layer 121 covering both sides of the support 122, the outer edges of which are crimped and fixed to form a seal 123. The paper-containing sheet 2 has, except for the seal 123, first high hydroxyl group concentration regions 11, second high hydroxyl group concentration regions 14, and openings 101 formed in a grid pattern as shown in Fig. 37, and the description of Fig. 37 is incorporated herein.

[0126] The absorbent pad 120 is stacked and housed in a case (not shown), and when it is removed from the case, the release of compression acts as a trigger force, causing the first high hydroxyl concentration region 11 and the second high hydroxyl concentration region 14 to bend, resulting in a zigzag cross-sectional shape as shown in Figure 49. This causes the space between the pair of absorbent layers 121 to expand, increasing the absorbent capacity for liquids such as menstrual blood and preventing leakage, and also making it possible to reduce discomfort caused by the absorbent layer 121 sticking too closely to the skin due to the unevenness of the support 122.

[0127] 50 is a plan view showing a conical structure 124 as a fourteenth embodiment of the present invention. The conical structure 124 has a square-shaped paper-containing sheet 2 with a circular central hole 125 formed in the center. On the upper surface of the paper-containing sheet 2, straight first hydroxyl group high concentration regions 11 are formed radially from the central hole 125, at equal angular intervals around the central hole 125. Furthermore, a weakened line 126 extending radially from the outer periphery to the central hole 125 is formed in a portion of the paper-containing sheet 2, allowing the sheet to be easily torn along this weakened line 126 by hand. In this fourteenth embodiment, the second hydroxyl group high concentration region 14 is not required.

[0128] With this conical structure 124, when the weakened line 126 is torn, this triggers the stress generated by the first hydroxyl group high concentration region 11, causing the conical structure 124 to deform into a conical shape with the central hole 125 at its apex. Figures 51 and 52 show photographs of the conical structure 124 shown in Figure 50, with Figure 51 showing the structure before the weakened line 126 is torn and Figure 52 showing the structure after the weakened line 126 is torn and deformed into a conical shape. As shown in Figures 42 and 43, the paper-containing sheet 2 preferably has a protective film 104 attached to at least its upper surface via an adhesive layer 103. The conical structure 124 can also be used as a dish or container by placing food or other contents in the recess with the pointed end facing downward. It can also be used as a protective cover or the like by placing the pointed end facing upward over an object.

[0129] 51 and 52, a square tracing paper measuring 153 μm in thickness and 200 mm in length and width was used as the paper-containing sheet 2, a circular hole with a diameter of 10 mm was formed as the central hole 125, and a pattern of first hydroxyl group-rich regions 11 measuring 0.95 mm in width and 70 mm in length was formed radially around the central hole 125 at 6° intervals by printing pure water using an inkjet printer. Approximately 2 minutes after printing, 10 μm-thick polyethylene protective films 104 were attached to both sides of the paper-containing sheet 2 with adhesive layers 103 formed by spraying "3M Spray 55" (a 3M product name) to form conical structures 124. It was confirmed that the conical structures 124 actually deformed into a cone shape.

[0130] 53 is a plan view showing a catalyst unit 127 as a 15th embodiment of the present invention. This catalyst unit 127 has a cylindrical catalyst container 128, a paper-containing sheet 2 provided inside this catalyst container 128, and catalyst layers 131 fixed to both sides of the paper-containing sheet 2. Both ends of the catalyst container 128 are tapered to form an inlet section 129 and an outlet section 130 that are connected to the outside.

[0131] The paper-containing sheet 2 is a long rectangle, and has first hydroxyl group high concentration regions 11, second hydroxyl group high concentration regions 14, and openings 101 formed in a grid pattern as shown in Figure 37, and the explanation of Figure 37 is used for these. The long paper-containing sheet 2, with catalyst layers 131 fixed to both sides, is rolled into a spiral shape to form a cylinder, which is then enclosed in a catalyst container 128. Gaps are formed between each layer of the paper-containing sheet 2, and because the cross-sectional shape of the paper-containing sheet 2 is zigzag, the fluid flows while refracting within the gaps, making it possible to increase the efficiency of contact with the catalyst layer 131.

[0132] [16th Embodiment] Figures 54 and 55 show photographs of a cushioning material 100, a cushioning material for arranging small fruits and foods, such as strawberries and cherries, in a box, before and after deformation, according to the 16th embodiment of the present invention. The paper-containing sheet 2 of this cushioning material 100 does not have an adhesive layer 103 or a protective film 104 formed thereon. The paper-containing sheet 2 has first high-hydroxyl group concentration regions 11 on its front surface and second high-hydroxyl group concentration regions 14 on its back surface, formed in a grid pattern as shown in Figure 37 , with rectangular openings 101 formed at the intersections of the grid. The paper-containing sheet 2 measures 420 mm long x 297 mm wide and 123 μm thick, and is made of tracing paper. The distance between the centers of the openings 101 along the first high-hydroxyl group concentration regions 11 and the second high-hydroxyl group concentration regions 14 is 51 mm. The first high-hydroxyl group concentration regions 11 and the second high-hydroxyl group concentration regions 14 are 15 mm wide and were formed by printing pure water using an inkjet printer. FIG. 54 is a photograph of the state after printing, and FIG. 55 is a photograph of the state in which the cushioning material 100 is compressed from all sides (when a trigger force is applied).

[0133] 56 and 57 are photographs showing a cushioning material 133 with a protective film, as a 17th embodiment of the present invention, in which protective films 104 are attached to both sides of a paper-containing sheet 2 formed in the same manner as in the 16th embodiment via adhesive layers 103, and then openings 101 are formed. The shape of the cushioning material 133 with a protective film, the printing patterns of the first high hydroxyl group concentration region 11 and the second high hydroxyl group concentration region 14, and the size and arrangement of the openings 101 are the same as those of the cushioning material 100, except that the adhesive layers 103 and protective films 104 are formed on both sides of the paper-containing sheet 2. Note that the adhesive layers 103 and protective films 104 do not have openings 101 formed in them. The cushioning material was manufactured as follows. After printing pure water on the paper-containing sheet 2 using an inkjet printer, approximately 10 minutes later, polyethylene protective films 104 each having a thickness of approximately 10 μm were attached to both sides of the paper-containing sheet 2 with adhesive layers 103 formed by spraying commercially available spray glue (3M Corporation, product name: 3M Spray Glue 55), the margins were cut off with a laser cutter, and the edge surfaces of the protective film 104 were melted to form edge protective films 105, sealing the cross section of the paper-containing sheet 2. The sheet was then heated to 90° C. for 5 minutes with an electric heater to cause thermoplastic deformation of the protective film 104 following the shape of the paper-containing sheet 2, after which bending was adjusted by hand to obtain a cushioning material 133 with a protective film.

[0134] Fig. 56 is a photograph of the state after protective film 104 has been attached, and Fig. 57 is a photograph of the state in which cushioning material 133 with protective film is compressed from all sides (a state in which a trigger force is applied). As is clear from a comparison of Fig. 55 and Fig. 57, cushioning material 133 with protective film 104 fixed to both sides with adhesive layer 103 also experiences deformation similar to that of cushioning material 100 without protective film 104.

[0135] Figure 58 is a photograph of the cushioning material 133 with protective film of Figure 57 compressed and placed into a packaging box for strawberries (117 mm length x 210 mm width x 50 mm height), with a strawberry placed in the central depression (pocket). As such, the cushioning material 133 with protective film having a complex three-dimensional shape can be easily manufactured by inkjet printing, and furthermore, the cushioning material 133 is formed with the moisture-proof protective film 104, so that the strawberries can be preserved with good flavor for a long period of time.

[0136] [Moisture absorption experiment] A portion of the cushioning material 100 of the 16th embodiment, in which the protective film 104 is not formed on the paper-containing sheet 2, and a portion of the cushioning material 133 of the 17th embodiment, in which the protective film 104 is formed, were used as samples to examine the difference in moisture absorption between the samples. The surface area (one side) of the cut-out samples was 150 cm ２ The internal volume was 430 cm ３ The two airtight containers were placed in a constant temperature and humidity environment with the lids open. The temperature was room temperature. The constant humidity environment was conditioned using a saturated salt method using high-humidity NaCl, and the relative humidity was approximately 75%. After the temperature and humidity had stabilized, each sample was sealed in an airtight container together with a humidity sensor, and the humidity was measured over time using the humidity sensor. The results are shown in Figure 60.

[0137] 60, in the sample of the 16th embodiment without the protective film 104, the relative humidity dropped to about 60% after about 1000 seconds, whereas in the sample of the 17th embodiment with the protective film 104, the relative humidity remained almost constant at about 73% after about 1000 seconds. It was found that the protective film 104 prevented the paper-containing sheet 2 from absorbing moisture.

[0138] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. The components of the above embodiments may be combined with each other, or other known configurations may be combined. For example, in addition to the above embodiments, the present invention can be applied to skin-worn items (cosmetics), electrostatic adhesive pads, wristbands, tourniquets, etc., from the viewpoint of maintaining an appropriate distance from an object by deforming the paper-containing sheet 2. From the viewpoint of increasing the surface area, the present invention can be applied to filters in addition to catalytic units. From the viewpoint of imparting a curved shape, the present invention can be applied to filters, speakers, ultrasonic elements, displays, hats, helmets, shoe insoles, etc. From the viewpoint of compactness through deformation, the present invention can be applied to space shelters, furniture, tableware, parachutes, etc. From the viewpoint of changing optical properties through deformation, the present invention can be applied to anti-peeping window and wall structures. From the viewpoint of cushioning function, the present invention can be applied to helmets, protectors for drone equipment, and propellers. From the viewpoint of changing insulation and heat resistance through deformation, the present invention can be applied to drink sleeves, etc. From the viewpoint of the pop-up effect through deformation, the present invention can be applied to picture books. From the viewpoint of deadfolding, the present invention can be applied to stickers, sticky notes, office equipment, etc.

[0139] According to the present invention, by applying a trigger force to a part of a paper-containing structure having a first hydroxyl group-rich region and a second hydroxyl group-rich region, the balance between the tensile stress and the deformation resistance force within the paper-containing structure changes, causing the structure to switch in at least one direction between a first shape and a second shape. This switching action can realize various functions, making the present invention industrially applicable.

[0140] 1 Paper-containing structure 1a First surface 1b Second surface 2 Paper-containing sheet 5 Mountain fold line 6 Valley fold line 9 Water 11 First hydroxyl group high concentration region 14 Second hydroxyl group high concentration region 20, 30, 40, 50, 60, 70, 80, 90, 100 Paper-containing structure 22 Weakened line 61 Opening 62 Ring-shaped convex portion 70 Drone gripping tool 71 Roll deformation portion 73 Opening 74 Drone 75 Supporting tool 77 Article 80 Cushioning material 81 Opening 82 Cylindrical wall portion 83 Support portion 90 Cushioning material 91 Opening 92 Cylindrical wall portion 93 Support portion 100 Cushioning material 101 Opening 102 Rough portion 103 Adhesive layer 104 Protective film 105 End surface protective film 106 Adhesive layer 107 Nonwoven fabric 108 Circuit layer 109 Protective film 110 Sensing pad 111 Sensor 112 Cable 113 Head 120 Absorbent pad 121 Absorbent layer 122 Support 123 Sealing portion 124 Conical structure 125 Central hole 126 Weakened line 127 Catalyst unit 128 Catalyst container 129 Inlet portion 130 Outlet portion 131 Catalyst layer 132 Passage 133 Cushioning material with protective film

Claims

1. A paper-containing structure formed by a dry paper-containing sheet comprising paper, the paper-containing sheet has a first surface and a second surface that face each other; a first hydroxyl group high concentration region having a higher hydroxyl group density than other portions of the first surface is formed in a band shape on the first surface; a second hydroxyl group high concentration region having a higher hydroxyl group density than other portions of the second surface is formed in a band shape on the second surface; a tensile stress is generated in each of the first hydroxyl group high concentration region and the second hydroxyl group high concentration region in the width direction of the strip-like shape, the first hydroxyl group high concentration region and the second hydroxyl group high concentration region intersect at the longitudinal midpoint when the paper-containing sheet is viewed in a plane, and the paper-containing sheet is curved by the tensile stress generated within the second hydroxyl group high concentration region that tends to shrink the second hydroxyl group high concentration region in the width direction, and the first shape is maintained by counteracting the tensile stress generated within the first hydroxyl group high concentration region that tends to shrink the first hydroxyl group high concentration region in the width direction, The paper-containing structure is characterized in that, when a trigger force is applied to a part of the paper-containing structure, the tensile stress generated within the first hydroxyl group high concentration region overcomes the curvature caused by the second hydroxyl group high concentration region, causing the paper-containing sheet to bend in the width direction of the first hydroxyl group high concentration region and deform into a second shape.

2. In the first hydroxyl group high concentration region and the second hydroxyl group high concentration region, the wave number is 3331 cm －１ The paper-containing structure described in claim 1, characterized in that when infrared rays are reflected at a surface portion of the paper-containing structure using a total reflection measurement method using infrared rays and the infrared absorption spectrum of the surface portion is measured, the transmittance of the infrared rays is lower than that of the other portions.

3. The paper-containing structure according to claim 1 or 2, characterized in that one or more notches are formed in the paper-containing sheet, and the first stable state and the second stable state can be formed by the notches.

4. The paper-containing structure of claim 1 or 2, characterized in that the trigger force is generated by water penetration into the paper-containing structure, a change in humidity in the environment in which the paper-containing structure is placed, local compression of the paper-containing structure, heating of the paper-containing structure, cooling of the paper-containing structure, cutting of a part of the paper-containing structure, or application of an external force to the paper-containing structure.

5. The paper-containing structure according to claim 1 or 2, wherein the paper-containing structure is switched between the first shape and the second shape in both directions by applying the trigger force to a part of the paper-containing structure.

6. A gripping tool used to grip an object, comprising the paper-containing structure according to claim 1 or 2, the first shape is an open-ended article-releasing shape; The second shape is an article-grasping shape with the end narrowed, The trigger force is generated by the gripping tool colliding with an item or contacting a support surface on which the item is supported, thereby causing the paper-containing structure to change from the item-releasing shape to the item-grasping shape and grasp the item.

7. A gripping tool for a drone, comprising the gripping tool according to claim 6, and having a fixing part at the center of the gripping tool that is fixed to a support part of the drone.

8. A cushioning material comprising the paper-containing structure according to claim 1 or 2, and used to arrange one or more items therein, the paper-containing structure has an origami structure; The first shape is a contracted shape in which the paper-containing structure is folded and has no pocket, or a flat shape in which the paper-containing structure is unfolded, the second shape is an expanded shape in which the paper-containing structure is expanded to form one or more pockets; A cushioning material characterized in that it changes from the contracted shape or flat shape to the expanded shape when a trigger force is applied to a part of the paper-containing structure.

9. An origami device comprising: a paper-containing structure according to claim 1 or 2; and at least one of an electronic element and wiring provided on at least one of the first surface and the second surface of the paper-containing structure.

10. A cushioning material comprising the paper-containing structure according to claim 1 or 2, and used to arrange one or more items therein, the paper-containing structure has an origami structure; The first shape is a contracted shape in which the paper-containing structure is folded and has no pocket, or a flat shape in which the paper-containing structure is unfolded, the second shape is an expanded shape in which the paper-containing structure is expanded to form one or more pockets; A cushioning material characterized in that it changes from the contracted shape or flat plate shape to the expanded shape when a trigger force is applied to a part of the paper-containing structure.

11. A cushioning material comprising the paper-containing structure according to claim 1 or 2, the paper-containing structure has one or more openings, and the first hydroxyl group-rich region and the second hydroxyl group-rich region disposed around the openings; The first shape is a flat shape in which the paper-containing structure is unfolded, The second shape is a three-dimensional shape in which the paper-containing structure has a cylindrical wall portion standing on the periphery of the opening and a support portion extending from the cylindrical wall portion, A cushioning material characterized in that it changes from the flat shape to the three-dimensional shape when a trigger force is applied to a part of the paper-containing structure.

12. A method for producing the paper-containing structure according to claim 1 or 2, comprising: applying a liquid containing water to the first surface and the second surface of the paper-containing sheet at locations where the first hydroxyl group high concentration region and the second hydroxyl group high concentration region are to be formed; and drying the liquid.

13. 3. The paper-containing structure according to claim 1, wherein a flexible protective film is attached to at least a portion of at least one of the first surface and the second surface of the paper-containing sheet.

14. 3. The paper-containing structure according to claim 1, wherein a flexible protective film is attached to each of the first and second surfaces of the paper-containing sheet.

15. A paper-containing structure formed by a dry paper-containing sheet comprising paper, the paper-containing sheet has a first surface and a second surface that face each other; a first hydroxyl group high concentration region is formed on the first surface, the first hydroxyl group high concentration region having a higher density of hydroxyl groups than other portions of the first surface; a second hydroxyl group high concentration region is formed on the second surface, the second hydroxyl group high concentration region having a higher density of hydroxyl groups than other portions of the second surface; a tensile stress is generated in each of the first hydroxyl group high concentration region and the second hydroxyl group high concentration region, the first hydroxyl group high concentration region and the second hydroxyl group high concentration region intersect with each other when the paper-containing sheet is viewed in plan; the tensile stress in the first hydroxyl group high concentration region on the first surface and the tensile stress in the second hydroxyl group high concentration region on the second surface are balanced with the anti-deformation force of the paper-containing sheet when the paper-containing structure is in a first shape, forming a first stable state and allowing the first shape to be maintained, and also when the paper-containing structure is in a second shape, they are balanced with the anti-deformation force of the paper-containing sheet, forming a second stable state and allowing the second shape to be maintained; A paper-containing structure, characterized in that a flexible protective film is formed on the entire first and second surfaces of the paper-containing sheet.

16. The paper-containing structure described in claim 15, characterized in that the paper-containing sheet has a Miura fold shape, and the first hydroxyl group high concentration region and the second hydroxyl group high concentration region are formed along the fold lines of the Miura fold shape.

17. The paper-containing structure according to claim 15 or 16, wherein an opening is formed in the paper-containing sheet at the intersection where the first hydroxyl group high concentration region and the second hydroxyl group high concentration region intersect.

18. 17. The paper-containing structure according to claim 15, wherein an end surface protective film connected to the protective film is formed on the end surface of the paper-containing sheet.