cushioning material

Abstract

To provide a buffer material enabling cushioning property to be improved while ensuring degree of freedom in deforming.SOLUTION: A buffer material of the present invention includes cellulose fibers and a binding material for binding the cellulose fibers and has a cushioning sheet having sheet-like shape. The cushioning sheet protrudes toward at least one surface side and has a plurality of first protrusions provided in lattice pattern. In addition, the cushioning sheet has preferably a plurality of second protrusions that protrude more than the first protrusion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention relates to a cushioning material. [Background technology]

[0002] In recent years, there has been a demand for cushioning materials that reduce environmental impact and can replace plastic materials. Processing methods for reusing waste paper have been known for some time. For example, Patent Document 1 discloses a cushioning material using crepe paper. Crepe paper is made by forming wrinkles in a base paper made from recycled waste paper and then processing it to solidify the wrinkles with, for example, a shape-retaining agent, giving it the property of expanding and contracting in the direction intersecting the wrinkles. Such cushioning materials are in the form of corrugated sheets and are used to match the size of the packaging material or to wrap the object to be protected. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-199325 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, because the cushioning material described in Patent Document 1 is corrugated, it is easy to deform it by forming folds along the direction in which the corrugation repeats, or by rolling it along that direction, but it is difficult to deform it in a direction other than that. Therefore, there are limitations on the direction of deformation. [Means for solving the problem]

[0005] The present invention provides a cushioning material comprising a sheet-like cushioning sheet containing cellulose fibers and a binding material for binding the cellulose fibers, The cushioning sheet is characterized by having a plurality of first protrusions that project toward at least one side and are arranged in a grid pattern. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a schematic diagram showing an example of a manufacturing apparatus capable of producing the cushioning material of the present invention. [Figure 2] Figure 2 is an enlarged cross-sectional view of the cushioning material of the present invention (first embodiment). [Figure 3] Figure 3 is an enlarged plan view of the cushioning material of the present invention (first embodiment). [Figure 4] Figure 4 is a cross-sectional view of the cushioning material of the present invention (second embodiment). [Modes for carrying out the invention]

[0007] Preferred embodiments of the present invention will be described in detail below. <First Embodiment> Figure 1 is a schematic diagram showing an example of a manufacturing apparatus capable of producing the cushioning material of the present invention. Figure 2 is an enlarged cross-sectional view of the cushioning material of the present invention. Figure 3 is an enlarged plan view of the cushioning material of the present invention. For the sake of explanation, in the following, the upper part in Figures 1 and 2 (and also in Figure 4) will be referred to as "top" and the lower part as "bottom".

[0008] The embodiments described below illustrate examples of the present invention. The present invention is not limited in any way to the embodiments described below, and includes various modifications that do not alter the essence of the present invention. Not all of the configurations described below are necessarily essential to the present invention.

[0009] First, let me explain about cushioning materials. The cushioning material WS of this embodiment has a cushioning sheet 1A. The cushioning sheet 1A includes a plurality of cellulose fibers and a binding material that binds the cellulose fibers together.

[0010] Cellulose fibers are natural materials rich in plant origin. By using cellulose fibers as fibers, it is possible to suitably cope with environmental problems and the conservation of buried resources, etc., and it is also preferable from the viewpoints of stable supply of cushioning material WS and cost reduction. Further, among various fibers, cellulose fibers have particularly high theoretical strength, and are also advantageous from the viewpoint of improving the strength of the cushioning material.

[0011] Cellulose fibers are usually mainly composed of cellulose, but may contain components other than cellulose. Examples of such components include hemicellulose, lignin, and the like.

[0012] However, the content rate of lignin in the cellulose fibers is preferably 5.0 mass% or less, more preferably 3.0 mass% or less, and even more preferably 1.0 mass% or less. Thereby, the cushioning performance of the cushioning material WS, particularly the compression characteristics, becomes more excellent.

[0013] Further, the content rate of cellulose in the cellulose fibers is preferably 50.0 mass% or more, more preferably 60.0 mass% or more, and even more preferably 80.0 mass% or more.

[0014] Further, as the cellulose fibers, for example, those subjected to treatments such as bleaching may be used. Also, the cellulose fibers may be those subjected to treatments such as ultraviolet irradiation treatment, ozone treatment, plasma treatment, and the like.

[0015] As cellulose fibers, in addition to natural cellulose fibers such as animal cellulose fibers and plant cellulose fibers, chemical cellulose fibers such as organic cellulose fibers, inorganic cellulose fibers, and organic-inorganic composite cellulose fibers may also be used. More specifically, cellulose fibers include those made from cellulose, cotton, hemp, kenaf, flax, ramie, jute, Manila hemp, sisal hemp, coniferous trees, broadleaf trees, etc. These may be used individually, in appropriate mixtures, or as regenerated cellulose fibers that have been purified or otherwise treated. Furthermore, cellulose fibers may be subjected to various surface treatments.

[0016] The average length of the cellulose fibers is not particularly limited, but is preferably 10 μm to 50 mm as the length-length weighted average cellulose fiber length, more preferably 20 μm to 5.0 mm, and even more preferably 30 μm to 3.0 mm.

[0017] This allows for improved stability, strength, and other properties of the cushioning material WS. Furthermore, it allows for improved cushioning performance of the cushioning material WS.

[0018] The cellulose fibers contained in the buffer sheet 1A, when considered as individual cellulose fibers, preferably have an average thickness of 1.0 μm or more and 1000 μm or less, and more preferably 2.0 μm or more and 100.0 μm or less.

[0019] This allows for improved stability and strength of the shape of the cushioning material WS. Furthermore, it improves the cushioning performance of the cushioning material WS. Additionally, it more effectively prevents unintended irregularities from forming on the surface of the cushioning material WS.

[0020] If the cross-section of a cellulose fiber is not circular, the diameter of a circle with an area equal to the area of ​​the cross-section shall be treated as the thickness of the cellulose fiber.

[0021] The average aspect ratio of the cellulose fibers, that is, the average length to the average thickness, is not particularly limited, but is preferably between 10 and 1000, and more preferably between 15 and 500.

[0022] This allows for improved stability and strength of the shape of the cushioning material WS. Furthermore, it improves the cushioning performance of the cushioning material WS. Additionally, it more effectively prevents unintended irregularities from forming on the surface of the cushioning material WS.

[0023] In this specification, the term "cellulose fiber" may refer to a single cellulose fiber or to an aggregate of multiple cellulose fibers. Furthermore, the cellulose fiber may also refer to cellulose fibers that have been loosened into fibers by a defibration treatment, i.e., defibrated material. Examples of materials to be defibrated include pulp sheets, paper, recycled paper, tissue paper, kitchen paper, cleaners, filters, liquid absorbents, sound absorbers, cushioning materials, mats, cardboard, etc., in which cellulose fibers are intertwined or bound together.

[0024] The cellulose fiber content in the cushioning sheet 1A is preferably 63.0% by mass or more and 90.0% by mass or less, more preferably 67.0% by mass or more and 88.0% by mass or less, and even more preferably 72.0% by mass or more and 86.0% by mass or less. This makes it possible to improve the strength and cushioning performance of the cushioning material WS.

[0025] The cushioning sheet 1A contains a binding material. The binding material has the function of binding cellulose fibers together, but it may also have functions other than those mentioned above. More specifically, for example, the binding material may have the function of preventing components other than cellulose fibers, such as colorants described later, from falling off the buffer material.

[0026] As a binding material, one that is thermoplastic is preferred. This makes it easier to bond cellulose fibers together by applying heat to melt or soften the binding material during the manufacturing process of the cushioning material, causing it to spread between the cellulose fibers.

[0027] The binder is preferably one that melts or softens at 200°C or below, and more preferably one that melts or softens at 160°C or below.

[0028] This allows for more favorable bonding of cellulose fibers through heat treatment at relatively low temperatures, which is preferable from an energy-saving standpoint.

[0029] The glass transition temperature of the bonding material is preferably 45°C to 95°C, and more preferably 50°C to 90°C.

[0030] This allows for more favorable bonding of cellulose fibers through heat treatment at relatively low temperatures, which is preferable from an energy-saving standpoint. Furthermore, it more effectively prevents the unintended softening of natural binding materials when, for example, the buffer material is placed in a high-temperature environment.

[0031] The binder may be a petroleum-based binder derived from petroleum, or a natural binder derived from natural sources.

[0032] Examples of petroleum-based binders include various synthetic resins such as thermoplastic resins, thermosetting resins, and photocurable resins.

[0033] Examples of thermoplastic resins among synthetic resins include AS resin, ABS resin, polypropylene, polyethylene, polyvinyl chloride, polystyrene, acrylic resin, polyester resin, polyethylene terephthalate, polyphenylene ether, polybutylene terephthalate, nylon, polyamide, polycarbonate, polyacetal, polyphenylene sulfide, and polyether ether ketone.

[0034] As a binder other than natural binders, biodegradable synthetic resins such as polylactic acid, polybutylene succinate, and polyhydroxybutanoic acid may be used.

[0035] By using biodegradable resins, the environmental compatibility of the cushioning material can be improved. Furthermore, the resin may be subjected to processes such as copolymerization or modification.

[0036] Examples of natural binders include natural resins such as rosin, dammar, mastic, copal, amber, shellac resin, kirin blood, sandarac, and colophonium; natural polymers such as starch and modified versions thereof; one or more selected from these can be used in combination; however, it is preferable that the natural binder includes shellac resin.

[0037] This makes it possible to improve the strength and cushioning performance of the cushioning material WS, as well as improve the processability of the cushioning material WS.

[0038] Starch is a polymer material in which multiple α-glucose molecules are polymerized by glycosidic bonds. Starch may be linear or branched.

[0039] As for starch, for example, various plant-derived starches can be used. Examples of starch raw materials include grains such as corn, wheat, and rice; legumes such as broad beans, mung beans, and adzuki beans; tubers such as potatoes, sweet potatoes, and tapioca; wild grasses such as dogtooth violets, bracken, and kudzu; and palms such as sago palm.

[0040] In addition, modified starch and altered starch may be used as the starch. Examples of modified starch include acetylated adipic acid crosslinked starch, acetylated starch, oxidized starch, sodium octenyl succinate starch, hydroxypropyl starch, hydroxypropylated phosphate crosslinked starch, phosphorylated starch, phosphate esterified phosphate crosslinked starch, urea phosphorylated esterified starch, sodium starch glycolate, and high amylose corn starch. Examples of altered starch include pregelatinized starch, dextrin, lauryl polyglucose, cationized starch, thermoplastic starch, and carbamate starch.

[0041] The content of the binding material in the buffer sheet 1A is preferably 12.0% by mass or more and 28.0% by mass or less, more preferably 14.0% by mass or more and 25.0% by mass or less, and even more preferably 15.0% by mass or more and 22.0% by mass or less. This makes the aforementioned effects even more pronounced.

[0042] Buffer sheet 1A only needs to contain cellulose fibers and a binding material, but it may also contain other components. Hereinafter, such components will also be referred to as "other components."

[0043] Other components include, for example, flame retardants, colorants, flocculation inhibitors, surfactants, fungicides, preservatives, antioxidants, UV absorbers, and oxygen absorbers.

[0044] The content of other components in the buffer sheet 1A is preferably 7.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less.

[0045] As shown in Figure 2, the cushioning sheet 1A has a sheet-like overall shape. The thickness of the cushioning sheet 1A is not particularly limited, but is preferably 0.1 mm or more and 10 mm or less, more preferably 0.1 mm or more and 8 mm or less, and even more preferably 0.2 mm or more and 5 mm or less.

[0046] This makes it possible to improve the strength and rigidity of the cushioning material WS. Furthermore, it improves processability, for example, when processing sheet-shaped cushioning material WS into three-dimensional cushioning material WS through processes such as deep drawing, and more effectively prevents the occurrence of wrinkles and tears.

[0047] The cushioning sheet 1A has a plurality of first protrusions 11A that project toward the upper surface in the illustrated configuration and a plurality of second protrusions 12A that project toward the other surface 21.

[0048] The first projections 11A are arranged in a grid pattern. Furthermore, the first projections 11A form a rectangle in a plan view of the cushioning sheet 1A. In other words, the cushioning sheet 1A has grooves arranged in a grid pattern. With this configuration, when the cushioning material WS is bent or rolled, it can be deformed in the same way regardless of the direction in which it is bent or rolled. Moreover, compared to a cushioning material with a flat surface that omits the first projections 11A, the first projections 11A can contact the object to be protected first and deform preferentially. Therefore, the impact applied from the object to be protected can be absorbed in stages. As a result, it has superior cushioning performance. In summary, by having the first projections 11A, it is possible to enhance cushioning performance while ensuring a degree of freedom during deformation.

[0049] The length of the side (maximum length) of the first projection 11A in a plan view is preferably 0.1 mm or more and 5 mm or less, and more preferably 0.2 mm or more and 3 mm or less.

[0050] This prevents the cushioning material (WS) from being hindered when it is folded or rolled up.

[0051] The protrusion amount (maximum protrusion amount) of the first projection 11A is preferably 0.1 mm or more and 5 mm or less, and more preferably 0.2 mm or more and 3 mm or less.

[0052] This allows the cushioning performance to be fully utilized, and prevents the cushioning material WS from being hindered when it is folded or rolled up.

[0053] Furthermore, the cushioning sheet 1A has a plurality of second protrusions 12A that protrude more than the first protrusion 11A. The presence of the second protrusions 12A allows the second protrusions 12A and then the first protrusion 11A to contact the object to be protected and deform in that order. Therefore, the impact from the object to be protected can be absorbed in multiple stages. As a result, the cushioning performance is further improved.

[0054] Furthermore, the second projection 12A is hemispherical in shape. This further enhances cushioning performance and more effectively prevents it from hindering the bending or rolling of the cushioning material WS.

[0055] The diameter (maximum length) of the second projection 12A in plan view is preferably 0.4 mm or more and 20 mm or less, and more preferably 2 mm or more and 10 mm or less.

[0056] This prevents the cushioning material (WS) from being hindered when it is folded or rolled up.

[0057] The protrusion amount (maximum protrusion amount) of the second projection 12A is preferably 0.2 mm or more and 10 mm or less, and more preferably 1 mm or more and 5 mm or less.

[0058] This allows the cushioning performance to be fully utilized, and prevents the cushioning material WS from being hindered when it is folded or rolled up.

[0059] Further, the maximum protrusion amount of the second protrusion 12A is preferably 1.1 times or more and 8 times or less, more preferably 1.5 times or more and 4 times or less, the maximum protrusion amount of the first protrusion 11A. Thereby, the cushioning performance can be further enhanced, and when the cushioning material WS is bent or rounded, it is possible to more effectively prevent the operation from being inhibited.

[0060] The density of the cushioning sheet 1A is not particularly limited, but is preferably 0.02 g / cm 2 or more and 0.20 g / cm 3 or less, more preferably 0.03 g / cm 3 or more and 0.15 g / cm 3 or less, still more preferably 0.05 g / cm 3 or more and 0.11 g / cm 3 or less.

[0061] Thereby, the strength and rigidity of the cushioning material WS can be made more excellent. Further, the durability of the cushioning material WS against impact can be made more excellent. Further, for example, when the cushioning material WS is processed into a cushioning material WS having a three-dimensional shape by deep drawing or the like, the workability can be made more excellent, and the occurrence of wrinkles and breakage can be more effectively prevented.

[0062] Particularly, when the cushioning material WS satisfies both the above-described thickness condition and density condition, the effects thereof act synergistically, and the effects as described above are more significantly exhibited.

[0063] The basis weight of the cellulose fiber in the cushioning sheet 1A is not particularly limited, but is preferably 150 g / m 2 or more and 650 g / m 2 or less, more preferably 160 g / m 2 or more and 600 g / m 2 or less, still more preferably 200 g / m 2 or more and 500 g / m 2The following is even more preferable. This makes it possible to improve the strength and rigidity of the cushioning material WS. It also makes it possible to improve the impact resistance of the cushioning material. Furthermore, it makes it possible to improve the processability when processing a sheet-like cushioning material WS into a three-dimensional cushioning material WS by processes such as deep drawing, and it is possible to more effectively prevent the occurrence of wrinkles and tears.

[0064] Thus, the cushioning material WS comprises cellulose fibers and a binding material that binds the cellulose fibers together, and has a cushioning sheet in the form of a sheet. Furthermore, the cushioning sheet 1A has a plurality of first protrusions 11A that project toward at least one side and are arranged in a grid pattern. As a result, when the cushioning material WS is bent or rolled, it can be deformed in the same way regardless of the direction in which it is bent or rolled. Moreover, compared to a cushioning material with a flat surface that omits the first protrusions 11A, the first protrusions 11A can contact the object to be protected first and deform preferentially. Therefore, the impact applied from the object to be protected can be absorbed in stages. As a result, it has superior cushioning performance. In summary, by having the first protrusions 11A, it is possible to enhance cushioning performance while ensuring a degree of freedom during deformation.

[0065] Furthermore, the first projection 11A forms a rectangle in a plan view of the cushioning sheet 1A. This facilitates the manufacturing of the cushioning sheet 1A and further enhances its cushioning performance.

[0066] The plan view shape of the first projection 11A is not particularly limited and may be, for example, a triangle or a polygon with pentagons or more sides, or it may be circular.

[0067] Furthermore, the planar shape of the second projection 12A is not particularly limited and may be, for example, a triangle, a rectangle, or a polygon with pentagons or more.

[0068] [Manufacturing equipment] Next, we will describe a manufacturing apparatus that can be used to produce cushioning material WS. Figure 1 is a schematic diagram showing an example of a manufacturing apparatus capable of producing cushioning material WS.

[0069] As shown in Figure 1, the manufacturing apparatus 100 includes a supply unit 10, a coarse crushing unit 12, a defibration unit 20, a sorting unit 40, a first web forming unit 45, a rotating body 49, a mixing unit 50, a stacking unit 60, a second web forming unit 70, a buffer material forming unit 80, a cutting unit 90, and a humidifying unit 78.

[0070] The supply unit 10 supplies raw materials to the crushing unit 12. The supply unit 10 is, for example, an automatic feeding unit for continuously feeding raw materials to the crushing unit 12. The raw materials supplied to the crushing unit 12 can be any material containing cellulose fibers.

[0071] The coarse crushing unit 12 cuts the raw material supplied by the supply unit 10 into fine pieces in the air or other air. The shape and size of the fine pieces are, for example, several centimeters square. In the illustrated example, the coarse crushing unit 12 has a coarse crushing blade 14, which can cut the raw material that is fed in. For example, a shredder can be used as the coarse crushing unit 12. The raw material cut by the coarse crushing unit 12 is received in the hopper 1 and then transported to the defibration unit 20 via the pipe 2.

[0072] The defibration unit 20 defibrates the raw material that has been cut by the crushing unit 12. Here, "defibration" means separating the raw material, which is made up of multiple cellulose fibers bound together, into individual cellulose fibers. The defibration unit 20 also has the function of separating substances such as resin particles, ink, toner, fillers, and anti-bleeding agents that are attached to the raw material from the cellulose fibers.

[0073] The material that passes through the defibration section 20 is called "defibrated material." In addition to the unraveled defibrated cellulose fibers, the "defibrated material" may also contain resin particles separated from the cellulose fibers during the unraveling process, as well as colorants such as inks, toners, and fillers, and additives such as anti-bleeding agents and paper strength enhancers. Examples of resin particles separated from cellulose fibers include particles containing resin used to bind multiple cellulose fibers together.

[0074] The defibration unit 20 performs defibration in a dry manner. Unlike the wet method, which dissolves the material in a slurry in a liquid such as water, the dry method refers to processing the defibration in air such as the atmosphere. In this embodiment, an impeller mill is used as the defibration unit 20. The defibration unit 20 has the function of generating an airflow that sucks in the raw material and discharges the defibrated material. As a result, the defibration unit 20 can suck in the raw material from the inlet 22 along with the airflow it generates, process it for defibration, and transport the defibrated material to the outlet 24. The defibrated material that has passed through the defibration unit 20 is transferred to the sorting unit 40 via the pipe 3. The airflow used to transport the defibrated material from the defibration unit 20 to the sorting unit 40 may be the airflow generated by the defibration unit 20, or an airflow generating device such as a blower may be provided and its airflow may be used.

[0075] The sorting unit 40 receives the defibrated material from the defibration unit 20 through the inlet 42 and sorts it according to the length of the cellulose fibers. The sorting unit 40 has a drum unit 41 and a housing unit 43 that houses the drum unit 41. For example, a sieve is used as the drum unit 41. The drum unit 41 has a mesh and can separate the first sorted material, which is cellulose fibers or particles that are smaller than the mesh opening and pass through the mesh, from the second sorted material, which is cellulose fibers, undefibrated pieces, and clumps that are larger than the mesh opening and do not pass through the mesh. For example, the first sorted material is transferred to the mixing unit 50 via the pipe 7. The second sorted material is returned to the defibration unit 20 via the discharge port 44 and pipe 8. Specifically, the drum unit 41 is a cylindrical sieve that is rotationally driven by a motor. For the mesh of the drum section 41, for example, wire mesh, expanded metal made by stretching a metal sheet with cuts in it, or perforated metal made by forming holes in a metal sheet using a press or the like can be used.

[0076] The first web forming unit 45 transports the first sorted material that has passed through the sorting unit 40 to the mixing unit 50. The first web forming unit 45 includes a mesh belt 46, tension rollers 47, and a suction unit 48.

[0077] The suction unit 48 can suck up the first sorted material, which has been dispersed into the air through the opening of the sorting unit 40, i.e., the opening of the mesh, onto the mesh belt 46. The first sorted material accumulates on the moving mesh belt 46, forming a web V. The basic configuration of the mesh belt 46, tension roller 47, and suction unit 48 is the same as that of the mesh belt 72, tension roller 74, and suction mechanism 76 of the second web forming unit 70, which will be described later.

[0078] The web V is formed into a soft, swollen state containing a lot of air by passing through the sorting section 40 and the first web forming section 45. The web V accumulated on the mesh belt 46 is fed into the pipe 7 and transported to the mixing section 50.

[0079] The rotating body 49 can cut the web V before it is transported to the mixing section 50. In the illustrated example, the rotating body 49 has a base 49a and projections 49b protruding from the base 49a. The projections 49b have, for example, a plate-like shape. In the illustrated example, there are four projections 49b, which are spaced equally apart. By rotating the base 49a in direction R, the projections 49b can rotate about the base 49a as an axis. By cutting the web V with the rotating body 49, for example, fluctuations in the amount of defibrated material supplied to the deposition section 60 per unit time can be reduced.

[0080] The rotating body 49 is located near the first web forming section 45. In the illustrated example, the rotating body 49 is located near the tension roller 47a, which is located downstream in the path of the web V, i.e., next to the tension roller 47a. The rotating body 49 is positioned so that the projection 49b can contact the web V, but does not contact the mesh belt 46 on which the web V is deposited. The shortest distance between the projection 49b and the mesh belt 46 is, for example, 0.05 mm or more and 0.5 mm or less.

[0081] The mixing unit 50 mixes the first sorted material that has passed through the sorting unit 40, in other words, the first sorted material conveyed by the first web forming unit 45, with an additive containing a natural binding material. The mixing unit 50 includes an additive supply unit 52 for supplying the additive, a pipe 54 for conveying the first sorted material and the additive, and a blower 56. In the illustrated example, the additive is supplied from the additive supply unit 52 to the pipe 54 via the hopper 9. The pipe 54 is continuous with the pipe 7.

[0082] In the mixing section 50, an airflow is generated by the blower 56, allowing the first sorted material and the additive to be mixed and conveyed within the pipe 54. The mechanism for mixing the first sorted material and the additive is not particularly limited; it may be agitated by high-speed rotating blades, or it may utilize the rotation of a container, such as a V-type mixer.

[0083] The additive supply unit 52 may be a screw feeder as shown in Figure 1, or a disc feeder (not shown). The additive supplied from the additive supply unit 52 includes the natural binding material mentioned above. At the time the natural binding material is supplied, the multiple cellulose fibers are not bound together. As the natural binding material passes through the buffer material forming unit 80, a portion of it melts and binds the multiple cellulose fibers in the surface area of ​​the buffer material WS.

[0084] The additives supplied from the additive supply unit 52 may include, in addition to natural binders, colorants for coloring cellulose fibers, flocculation inhibitors to suppress the flocculation of cellulose fibers and natural binders, and flame retardants to make cellulose fibers and other materials less flammable, depending on the type of buffer material WS being manufactured. The mixture that has passed through the mixing unit 50, that is, the buffer material manufacturing composition which is a mixture of the first sorted material and additives, is transferred to the accumulation unit 60 via the pipe 54.

[0085] The deposition section 60 introduces the mixture that has passed through the mixing section 50 through the inlet 62, loosening the entangled cellulose fiber defibrations and dispersing them in the air as they fall. As a result, the deposition section 60 can deposit the mixture uniformly onto the second web-forming section 70.

[0086] The deposition section 60 has a drum section 61 and a housing section 63 that houses the drum section 61. A rotating cylindrical sieve is used as the drum section 61. The drum section 61 has a mesh and drops cellulose fibers or particles smaller than the mesh opening size contained in the mixture that has passed through the mixing section 50. The configuration of the drum section 61 is, for example, the same as the configuration of the drum section 41.

[0087] Furthermore, the "sieve" of the drum section 61 does not necessarily have the function of selecting specific objects. In other words, the "sieve" used as the drum section 61 simply means one equipped with a mesh, and the drum section 61 may simply allow all of the mixture introduced into the drum section 61 to sift.

[0088] The second web forming section 70 deposits the material that has passed through the deposit section 60 to form a web W, which is a deposit that will become the buffer material WS. At this time, a mold (not shown in Figure 1) can be placed on the mesh belt 72 to act as a receiving tray, and the web can be formed inside the mold. The second web forming section 70 includes, for example, a mesh belt 72, a tensioning roller 74, and a suction mechanism 76. As the mold, for example, one corresponding to the shape of the buffer sheet 1A shown in Figures 2 and 3 can be used.

[0089] As the mesh belt 72 moves, it deposits the material that passes through the openings of the accumulation section 60, i.e., the openings of the mesh, onto the mold. The mesh belt 72 and the mold are stretched by tension rollers 74, and are configured to be difficult for material to pass through but allow air to pass through. The mesh belt 72 moves as the tension rollers 74 rotate. As the mesh belt 72 moves continuously, the material that passes through the accumulation section 60 continuously accumulates, forming a web W on the mold on the mesh belt 72. The mesh belt 72 and the mold are made of, for example, metal, resin, cloth, nonwoven fabric, etc.

[0090] The suction mechanism 76 is located below the mesh belt 72, that is, on the side opposite to the deposition section 60. The suction mechanism 76 can generate a downward airflow, that is, an airflow directed from the deposition section 60 towards the mesh belt 72. This suction mechanism 76 can draw the mixture dispersed in the air by the deposition section 60 onto the mesh belt 72. This increases the discharge velocity from the deposition section 60. Furthermore, the suction mechanism 76 can create a downflow in the path of the falling mixture, suppressing entanglement of defibrated material and additives during the fall.

[0091] As described above, a web W is formed in a soft, swollen state containing a lot of air through the web formation process carried out in the deposition section 60 and the second web formation section 70. The web W deposited on the mold on the mesh belt 72 is transported to the buffer material formation section 80.

[0092] The thickness of the web W, which is the sediment transported to the buffer material forming section 80, is preferably 2.0 mm or more and 150 mm or less, more preferably 3.0 mm or more and 120 mm or less, and even more preferably 5.0 mm or more and 100 mm or less.

[0093] Furthermore, the density of web W is 0.01 g / cm³. 3 More than 0.05g / cm 3 Preferably, it is 0.02 g / cm³. 3 More than 0.04g / cm 3 The following is more preferable.

[0094] Furthermore, the basis weight of Web W is 150g / m². 2 More than 650g / m 2 Preferably, it is 160 g / m². 2 More than 600g / m 2 It is more preferable that it be less than 200 g / m 2 More than 500g / m 2 The following is even more preferable:

[0095] The cushioning material forming section 80 includes a support section 81 and a mold 82. A heating element is built into at least one of the support section 81 and the mold 82. The support section 81 is composed of a flat plate-shaped member. The mold 82 is located on the opposite side of the support section 81 via a web W during transport.

[0096] The mold 82 can be in a state where it is pressed against the support portion 81 to heat and pressurize the web W, or in a state where it is separated from the support portion 81.

[0097] In this embodiment, the web W is conveyed intermittently, and the support section 81 and mold 82 repeatedly undergo heating and pressurizing conditions, thereby enabling the production of the cushioning material WS.

[0098] The support portion 81 may be a male type corresponding to the shapes of the first projection 11A and the second projection 12A. In this case, the first projection 11A and the second projection 12A can be formed on both sides of the cushioning sheet 1A.

[0099] Furthermore, the configuration is not limited to the above. For example, heating and pressing may be performed using a pair of heating and pressing rollers having irregularities that correspond to the shapes of the first projection 11A and the second projection 12A. In this case, the cushioning material WS can be manufactured while the web W is continuously conveyed. Therefore, productivity is excellent.

[0100] In this process, the heating temperature is preferably between 10°C and 250°C above the melting or softening point, and more preferably between 20°C and 220°C above the melting or softening point, if the binder material has a melting or softening point. If the binder material is starch or the like, the heating temperature is preferably between 50°C and 100°C, which is the temperature at which gelatinization begins when water (30% by mass or less) is added.

[0101] This effectively prevents unintended modification and deterioration of the components of the cushioning sheet 1A, while efficiently forming bonds between cellulose fibers using natural binding materials. This improves the productivity of the cushioning sheet 1A and enhances its strength, cushioning performance, and other properties. It is also preferable from an energy-saving standpoint.

[0102] Furthermore, the pressurizing pressure in this process is preferably 0.50 MPa or less, more preferably 0.01 MPa to 0.45 MPa, and even more preferably 0.03 MPa to 0.40 MPa.

[0103] This allows the manufactured cushioning sheet 1A to have appropriate voids while efficiently forming bonds between cellulose fibers using natural binding materials, thereby improving the strength, cushioning performance, and other properties of the cushioning sheet 1A. It is also preferable from an energy-saving standpoint.

[0104] The heating and pressurizing time in this process is preferably between 1 second and 300 seconds, more preferably between 10 seconds and 60 seconds, and even more preferably between 15 seconds and 45 seconds.

[0105] This allows for improved productivity of the cushioning material WS while also enhancing its strength, cushioning performance, and other properties. It is also preferable from an energy-saving perspective.

[0106] The manufacturing apparatus 100 of this embodiment may have a cutting section 90 as needed. In the illustrated example, the cutting section 90 is provided downstream of the cushioning material forming section 80. The cutting section 90 cuts the mold containing the cushioning material WS formed by the cushioning material forming section 80. In the illustrated example, the cutting section 90 has a first cutting section 92 that cuts the mold containing the cushioning material WS in a direction intersecting the conveying direction of the cushioning material WS, and a second cutting section 94 that cuts the cushioning material WS in a direction parallel to the conveying direction. The second cutting section 94 cuts the mold containing the cushioning material WS that has passed through the first cutting section 92, for example.

[0107] Furthermore, the manufacturing apparatus 100 of this embodiment may also have a humidifying unit 78. In the illustrated example, it is located downstream of the cutting unit 90 and upstream of the discharge unit 96. The humidifying unit 78 can provide water or water vapor to the buffer material WS. Specific embodiments of the humidifying unit 78 include, for example, spraying a mist of water or an aqueous solution, spraying water or an aqueous solution, or ejecting water or an aqueous solution from an inkjet head and applying it to the material.

[0108] The manufacturing apparatus 100 has a humidification unit 78, which allows the formed cushioning material WS to be moistened. This makes the cellulose fibers softer due to the moisture. Therefore, when using the cushioning material WS to form containers or the like, wrinkles and tears become less likely to occur. In addition, moistening the cushioning material WS makes it easier to form hydrogen bonds between the cellulose fibers, which increases the density of the cushioning material WS and, for example, improves its strength.

[0109] In the example shown in Figure 1, the humidifying section 78 is located downstream of the cutting section 90. However, the same effect can be obtained if the humidifying section 78 is located downstream of the cushioning material forming section 80. In other words, the humidifying section 78 may be located downstream of the cushioning material forming section 80 and upstream of the cutting section 90.

[0110] By removing only the cushioning material WS from the mold in which it was formed, a cushioning material WS can be obtained as a three-dimensional molded body having, for example, a convex shape.

[0111] <Second Embodiment> Figure 4 is a cross-sectional view of the cushioning material of the present invention (second embodiment).

[0112] The following description of a second embodiment of the cushioning material of the present invention will be made with reference to this figure, focusing on the differences from the previously described embodiment, and omitting explanations of similar matters.

[0113] As shown in Figure 4, in this embodiment, a nonwoven fabric sheet 1B is provided on one side and the other side of the cushioning sheet 1A. The nonwoven fabric sheet 1B is bonded to the cushioning sheet 1A.

[0114] Because both sides of the cushioning sheet 1A are covered with a nonwoven fabric sheet in this way, it is possible to prevent or suppress the scattering of powder such as cellulose fibers from the cushioning sheet 1A. Therefore, it is possible to prevent or suppress the adhesion of powder such as cellulose fibers to the object to be protected.

[0115] The fibers constituting the nonwoven fabric sheet 1B are not particularly limited, but it is preferable that they be the same cellulose fibers used in the cushioning sheet 1A.

[0116] Furthermore, it is preferable that the average length of the fibers constituting the nonwoven fabric sheet 1B is longer than the average length of the cellulose fibers contained in the cushioning sheet 1A.

[0117] Furthermore, the nonwoven fabric sheet 1B may contain a binding material that connects the fibers together. This binding material is not particularly limited, but can be appropriately selected and used from, for example, the examples of binding materials included in the cushioning sheet 1A listed.

[0118] The thickness (average thickness) of the nonwoven fabric sheet 1B is not particularly limited, but is preferably 0.05 mm or more and 1 mm or less, and more preferably 0.1 mm or more and 0.5 mm or less.

[0119] This allows the first projection 11A and the second projection 12A to fully exert the effects described above. Furthermore, it is possible to more effectively prevent or suppress the scattering of powder such as cellulose fibers from the buffer sheet 1A.

[0120] Furthermore, the basis weight of nonwoven fabric sheet 1B is 10 g / m². 2 More than 100g / m 2 Preferably, it is 10 g / m 2 More than 50g / m 2 The following is more preferable. This makes it possible to more effectively prevent or suppress the scattering of powder such as cellulose fibers from the cushioning sheet 1A, and to ensure sufficient cushioning performance of the cushioning sheet 1A.

[0121] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto.

[0122] For example, the present invention includes configurations that are substantially identical to those described in the embodiments, such as configurations with the same function, method, and results, or configurations with the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0123] For example, the cushioning material of the present invention is not limited to those manufactured using the methods and manufacturing equipment described above. [Explanation of Symbols]

[0124] 1...Hopper, 1A...Cushioning sheet, 2,3,7,8...Tube, 9...Hopper, 10...Feeding section, 11A...First projection, 12A...Second projection, 12...Coarse crushing section, 14...Coarse crushing blade, 20...Fibre separation section, 22...Inlet, 24...Discharge port, 40...Sorting section, 41...Drum section, 42...Inlet, 43...Housing section, 44...Discharge port, 45...First web forming section, 46...Mesh belt, 47,47a...Tensioning roller, 48...Suction section, 49...Rotating body, 49a...Base, 49b...Protrusion, 5 0...Mixing section, 52...Additive supply section, 54...Pipe, 56...Blower, 60...Stacking section, 61...Drum section, 62...Inlet, 63...Housing section, 70...Second web forming section, 72...Mesh belt, 74...Tensioning roller, 76...Suction mechanism, 78...Humidification section, 80...Cushioning material forming section, 81...Support section, 82...Mold, 90...Cutting section, 92...First cutting section, 94...Second cutting section, 96...Discharge section, 100...Manufacturing equipment, R...Direction, V...Web, W...Web, WS...Cushioning material

Claims

1. It comprises cellulose fibers and a binding material for binding the cellulose fibers together, and is in the form of a sheet. A cushioning material made of a cushioning sheet, The aforementioned cushioning sheet has multiple components that protrude toward at least one side and are arranged in a grid pattern. The first projection and It has a plurality of second protrusions that protrude more than the first protrusion, A cushioning material that absorbs impacts from a protected object by deforming when the first and second protrusions come into contact with the protected object.

2. The cushioning material according to claim 1, wherein the first projection forms a rectangle in a plan view of the cushioning sheet.

3. The cushioning material according to claim 1, wherein the second projection is hemispherical.

4. The maximum protrusion of the second projection is 1.1 times or more and 8 times or less the maximum protrusion of the first projection. The cushioning material according to claim 1.

5. The basis weight of the cellulose fibers in the aforementioned cushioning sheet is 150 g / m² or more and 650 g / m² or more. A cushioning material according to any one of claims 1 to 4, wherein the m² is 1 or less.

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