Method for manufacturing cushioning material, and cushioning material

Abstract

To provide a buffer material manufacturing method enabling mechanical strength to be improved and a buffer material.SOLUTION: A manufacturing method of a buffer material P includes a defibrillation step to generate a fiber F by defibrillating a fabric under a drying condition, a mixing step to generate a mixture by mixing binder with the fiber F, an accumulation step to generate a web W by accumulating the mixture in the air, and a primary molding step to mold the web W by pressuring and heating.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cushioning material and a cushioning material.

Background Art

[0002] Conventionally, a method for manufacturing a cushioning material containing fibers and a resin has been known. For example, Patent Document 1 discloses a method for manufacturing an elastic fiber structure containing fibers derived from natural products and biodegradable heat-fusible synthetic fibers. The use of the elastic fiber structure is a cushioning material or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the manufacturing method described in Patent Document 1 has a problem that it is difficult to improve the mechanical strength as a cushioning material. Specifically, various fibers are mixed, passed through a carding machine, and then laminated. Therefore, the fiber length directions are likely to be aligned in a direction intersecting the lamination direction, and the entanglement between the fibers decreases. As a result, it becomes difficult to ensure the mechanical strength of the cushioning material, and there is a possibility that the cushioning material is easily deformed by an external force. That is, a method for manufacturing a cushioning material with improved mechanical strength has been demanded.

Means for Solving the Problems

[0005] The method for manufacturing a cushioning material includes a defibrating step of defibrating a fabric in a dry manner to generate fibers, a mixing step of mixing a binder with the fibers to generate a mixture, a depositing step of depositing the mixture in the air to generate a web, and a primary forming step of pressurizing and heating the web to form it.

[0006] The cushioning material comprises fibers obtained by dissecting a fabric including a plain weave or knit fabric, and a binder derived from natural materials that binds the fibers together, and has recesses shaped to correspond to the three-dimensional shape of the packaged object. [Brief explanation of the drawing]

[0007] [Figure 1] A flowchart illustrating the manufacturing method of the cushioning material according to the embodiment. [Figure 2] A schematic diagram showing the configuration of a cushioning material manufacturing device. [Figure 3] A schematic cross-sectional view showing the state of fibers in a plate-shaped cushioning material. [Figure 4] A schematic diagram showing the conformability of the cushioning material to the mold when it is compression molded (Figure 3). [Figure 5] A schematic cross-sectional view showing the state of fibers in a plate-shaped cushioning material. [Figure 6] A schematic diagram showing the conformability of the cushioning material to the mold when it is compression molded (Figure 5). [Figure 7] A schematic cross-sectional view showing the state of fibers in a conventional plate-shaped cushioning material. [Figure 8] A schematic diagram showing the conformability of the cushioning material to the mold when it is compression molded (Figure 7). [Modes for carrying out the invention]

[0008] The embodiments described below illustrate a method for manufacturing cushioning material for storing three-dimensional objects, and will be explained with reference to the drawings. In each of the following figures, the Z-axis, which is a coordinate axis, is added as needed, the direction indicated by the arrow is the +Z direction, and the direction opposite to the +Z direction is the -Z direction. The +Z direction may also be referred to as upward, and the -Z direction as downward. In Figure 2, the -Z direction coincides with the vertical direction.

[0009] Also, for the sake of illustration convenience, the sizes of each component are shown to differ from their actual dimensions. In cushioning material manufacturing equipment, the end of the conveying direction for raw materials and webs is sometimes called downstream, and the side going upstream in the conveying direction is sometimes called upstream.

[0010] 1.Cushioning material The cushioning material produced by the method for producing cushioning material according to this embodiment includes fibers and a binder as raw materials. The fibers and binder are derived from natural products from the viewpoint of reducing environmental impact. Furthermore, it is preferable that the fibers and binder are biodegradable.

[0011] Fibers are one of the main components of cushioning material and, along with binders, affect the physical properties of the cushioning material, such as its mechanical strength. Fibers obtained by defibrating fabric are used. From the viewpoint of resource recycling, it is preferable to use used fabrics such as old clothes.

[0012] The fabric preferably includes knitted fabric, plain weave fabric, and pile fabric. The fabric may also include nonwoven fabric.

[0013] Examples of fibers include natural fiber materials such as cotton, hemp, wool, silk, and regenerated cellulose. These fibers may be used individually or in combination of two or more. In particular, among the above fiber materials, it is preferable that the fabric contains cotton or wool, considering factors such as the ease of obtaining used clothing and the physical properties of the fibers.

[0014] The fibers may include synthetic fibers such as polypropylene, polyester, and polyurethane, but from the viewpoint of reducing environmental impact, it is preferable to use only fibers derived from natural materials.

[0015] The binder is used to bond the fibers together in the buffer material. The binder is a thermoplastic or thermosetting resin. Examples of resins include shellac, pine resin, dammar, polylactic acid, plant-derived polybutylene succinate, plant-derived polyethylene, and Kaneka's PHBH® (Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)). One of these resins may be used alone, or two or more may be used in combination. In particular, the binder is preferably a biodegradable resin from the viewpoint of reducing environmental impact.

[0016] The cushioning material may contain additives in addition to fibers and binders. Examples of additives include colorants, flame retardants, antioxidants, ultraviolet absorbers, anti-aggregation agents, antibacterial agents, fungicides, waxes, and mold release agents.

[0017] The cushioning material is manufactured using the above raw materials. The cushioning material has a recess for storing and protecting the packaged object. After being primarily formed into a plate shape or a块状 shape, the cushioning material is secondarily formed by compression molding or the like, and a recess having a shape corresponding to the three-dimensional shape of the packaged object is formed. The details of the manufacturing method of the cushioning material will be described later.

[0018] The shape of the recess is preferably a desired shape corresponding to the three-dimensional shape of the packaged object. For this purpose, the shape of the mold must be correctly reflected in the recess during compression molding. Therefore, in the cushioning material, it is necessary to suppress the occurrence of unintended deformation due to the pressing of the mold and improve the followability to the mold. That is, among the mechanical strengths of the cushioning material, the followability to the mold is an important physical property.

[0019] Examples of the packaged object include information terminal devices such as wristwatches, notebook computers, small game machines, smartphones, printers, and projectors, precision parts, models, pottery, porcelain, glassware, household appliances, and fresh produce.

[0020] 2. Manufacturing Method of Cushioning Material As shown in FIG. 1, the manufacturing method of the cushioning material according to the present embodiment includes a raw material supply step, a crushing step, a fiber separation step, a mixing step, a deposition step, a primary forming step, a cutting step, and a secondary forming step.

[0021] In the manufacturing method of the cushioning material, the cushioning material is manufactured through each step in the above order from the upstream raw material supply step to the downstream secondary forming step. The manufacturing method of the cushioning material of the present invention includes a fiber separation step, a mixing step, a deposition step, and a primary forming step, and the other steps are not limited to the above. Further, the cushioning material of the present invention may be used in a state where the primary forming step is completed and the secondary forming step is unfinished. The cushioning material that has not undergone the secondary forming step is in a plate shape or a块状 shape.

[0022] A specific example of a method for manufacturing cushioning material will be described along with a cushioning material manufacturing apparatus. The cushioning material manufacturing apparatus 1 in this embodiment is just one example and is not limited thereto.

[0023] As shown in Figure 2, the cushioning material manufacturing apparatus 1 is equipped with a supply unit 5, a crushing unit 10, a defibration unit 30, a mixing unit 60, a stacking unit 100, a web transport unit 70, a primary molding unit 150, and a cutting unit 160, arranged from upstream to downstream. Although not shown in the figure, the cushioning material manufacturing apparatus 1 is also equipped with a control unit that integrally controls the operation of each of the above components. In the cushioning material manufacturing method of this embodiment, a compression molding machine is used to perform a secondary molding process on the plate-shaped cushioning material P manufactured by the cushioning material manufacturing apparatus 1. A known device is used as the compression molding machine.

[0024] In the supply unit 5, the raw material supply process takes place. The supply unit 5 supplies raw materials to the crushing unit 10. The supply unit 5 is equipped with, for example, an automatic feeding mechanism 6, which continuously and automatically feeds the raw material fabric C into the crushing unit 10. The fabric C is a material containing the aforementioned fibers.

[0025] The coarse crushing section 10 performs a coarse crushing process. The coarse crushing section 10 shreds the fabric C supplied from the supply section 5 into fine pieces in an atmosphere such as air. The coarse crushing section 10 is a shredder, cutter mill, etc., having a coarse crushing blade 11. The fabric C is shredded into fine pieces by the coarse crushing blade 11. The planar shape of the fine pieces is, for example, a few millimeters square or irregular. The fine pieces are collected in the quantitative supply section 50.

[0026] The quantitative feeding unit 50 weighs the flakes and supplies them to the hopper 12 in a fixed quantity. The quantitative feeding unit 50 is, for example, a vibratory feeder. The flakes supplied to the hopper 12 are transported through the pipe 20 and reach the inlet 31 of the defibration unit 30.

[0027] The defibration process is carried out in the defibration unit 30. The defibration unit 30 dry-defibrates the fragments of the fabric C to produce fibers. The defibration unit 30 includes an inlet 31, an outlet 32, a stator 33, a rotor 34, and an airflow generating mechanism (not shown). The fragments of the fabric C are introduced into the interior of the defibration unit 30 via the inlet 31 by the airflow from the airflow generating mechanism. In this specification, "dry" means that the process is carried out in air, such as the atmosphere, rather than in a liquid.

[0028] The stator 33 and rotor 34 are positioned inside the defibration section 30. The stator 33 has a substantially cylindrical inner surface. The rotor 34 rotates along the inner surface of the stator 33. The strips of fabric C are sandwiched between the stator 33 and the rotor 34 and defibrated by the shear force generated between them.

[0029] The defibrated fibers preferably have a length-weighted average fiber length of 1.0 mm or more, and preferably a maximum fiber length of 5.0 mm or more. This prevents the fibers from becoming excessively short, further improving the mechanical strength of the cushioning material P. The length-weighted average fiber length of the fibers is determined by a method in accordance with ISO 16065-2:2007.

[0030] The longest fiber length is determined by the following method: The fibers are placed on a glass plate so that they do not overlap as much as possible. In this state, the fiber length of the fibers on the glass plate is measured using a Keyence VHX-5000 digital microscope. Specifically, the fiber length is determined from the digital photograph taken with the microscope using the measurement software included with the device. This operation is performed on 50 randomly selected fibers, and the longest fiber length is taken as the longest fiber length. Note that fiber length refers to the distance along the curve if the fiber is curved.

[0031] The fibers preferably have an aspect ratio of 0.9 or less. The aspect ratio of the fibers is the value obtained by dividing the shortest fiber length by the total fiber length. According to this, curved or bent fibers are included in the cushioning material P. As a result, bias in the orientation direction of the fibers in the cushioning material P is less likely to occur, and the fibers become more likely to intertwine with each other. This further improves the mechanical strength of the cushioning material P.

[0032] The aspect ratio of the fiber is determined by the following method: The fiber is imaged on a glass plate in the same manner as the longest fiber length. The shortest fiber length is the straight-line distance between both ends of the fiber. The fiber length and shortest fiber length are determined from this digital image using the measurement software attached to the device. This operation is performed on 50 randomly selected fibers, and the aspect ratio of the fiber is determined as the average value of the 50 fibers.

[0033] The fibers generated in the defibration section 30 are discharged into the pipe 40 from the outlet 32. The pipe 40 communicates with the inside of the defibration section 30 and the inside of the accumulation section 100. The fibers are transported from the defibration section 30 to the accumulation section 100 by the airflow generated by the airflow generation mechanism. A mixing section 60 is provided in the pipe 40 between the defibration section 30 and the accumulation section 100.

[0034] A mixing process is carried out in the mixing section 60. The mixing section 60 mixes fibers with binders and other materials in air to produce a mixture. The mixing section 60 includes hoppers 13 and 14, supply pipes 61 and 62, and valves 65 and 66.

[0035] Hopper 13 communicates with the inside of pipe 40 via supply pipe 61. In supply pipe 61, valve 65 is provided between hopper 13 and pipe 40. Hopper 13 supplies binder into pipe 40. Valve 65 adjusts the weight of binder supplied from hopper 13 to pipe 40. This adjusts the mixing ratio of fibers to binder. The binder may be supplied as a powder or as a molten material.

[0036] Hopper 14 communicates with the inside of pipe 40 via supply pipe 62. Valve 66 is provided between hopper 14 and pipe 40 in supply pipe 62. Hopper 14 supplies additives other than the binder into pipe 40. Valve 66 adjusts the weight of the additives supplied from hopper 14 to pipe 40. This adjusts the mixing ratio of the additives to the fibers and binder. Note that additives are not essential components in the buffer material P, and hopper 14 and supply pipe 62 may be omitted. Alternatively, the additives may be mixed with the binder beforehand and supplied from hopper 13.

[0037] The fibers and binders are mixed as they are transported through the pipe 40 to the deposition section 100 to form a mixture. To promote the formation of the mixture in the pipe 40 and to improve the transportability of the mixture, a blower or the like may be placed in the pipe 40 to generate airflow. The mixture is transported through the pipe 40 to the deposition section 100.

[0038] The deposition process is carried out in the deposition section 100. The deposition section 100 generates a web W by depositing a mixture containing fibers and binders in the air. The deposition section 100 has a drum section 101 and a housing section 102 that houses the drum section 101. The deposition section 100 takes the mixture from the pipe 40 into the drum section 101 and deposits it on the mesh belt 122 in a dry manner.

[0039] Below the stacking section 100, a web transport section 70 is arranged, which includes a mesh belt 122 and a suction mechanism 110. The suction mechanism 110 is positioned opposite the drum section 101, with the mesh belt 122 in between, in the direction along the Z-axis.

[0040] The drum section 101 is a cylindrical sieve that is rotationally driven by a motor (not shown). A mesh that functions as a sieve is provided on the side of the cylindrical drum section 101. The drum section 101 allows particles such as fibers and mixtures that are smaller than the mesh opening size of the sieve to pass from the inside to the outside. The mixture is dispersed into the air inside the housing section 102 after the entangled fibers are loosened by the drum section 101.

[0041] The fibers are dispersed in the air within the housing portion 102, and the fibers are randomly deposited on the mesh belt 122. As a result, the fibers in the web W are less likely to be oriented in a specific direction.

[0042] The sieve in the drum section 101 does not need to have the function of separating large fibers and other particles from the mixture. That is, the drum section 101 may loosen the fibers of the mixture and release all of the mixture into the housing section 102. The mixture dispersed in the air inside the housing section 102 is deposited on the upper surface of the mesh belt 122 by gravity and suction from the suction mechanism 110.

[0043] In the web W, the mass ratio of fibers to binder is preferably in the range of 15:85 to 45:55 in terms of fibers to binder. This ensures that various physical properties, including the mechanical strength, of the cushioning material P can be secured. Furthermore, the density and thickness of the manufactured cushioning material P are adjusted according to the basis weight of the web W.

[0044] The web conveying section 70 includes a mesh belt 122 and a suction mechanism 110. The suction mechanism 110 facilitates the accumulation of the mixture onto the mesh belt 122. The web conveying section 70 also conveys the web W formed from the mixture downstream by the rotation of the mesh belt 122.

[0045] The suction mechanism 110 is positioned below the drum section 101. The suction mechanism 110 sucks air from inside the housing section 102 through multiple holes in the mesh belt 122. As a result, the mixture released to the outside of the drum section 101 is sucked downward along with the air and deposited on the upper surface of the mesh belt 122. A known suction device such as a blower is used in the suction mechanism 110.

[0046] The multiple holes in the mesh belt 122 allow air to pass through but make it difficult for fibers and binders contained in the mixture to pass through. The mesh belt 122 is an endless belt and is stretched by three tension rollers 121.

[0047] The mesh belt 122 moves downstream as the tension roller 121 rotates, with its upper surface moving downstream. In other words, the mesh belt 122 rotates clockwise in Figure 2. As the mesh belt 122 rotates due to the tension roller 121, the mixture is continuously deposited, forming a web W. The web W contains a relatively large amount of air and is soft and inflated. The web W is transported downstream as the mesh belt 122 moves.

[0048] Here, the web W may be laminated with a nonwoven fabric or the like. Specifically, when the web W is piled on the mesh belt 122, a nonwoven fabric is interposed between the mesh belt 122 and the web W. Also, the upper surface of the web W is covered with a nonwoven fabric. By continuously supplying the nonwoven fabric to the web W from above and below, the web W is laminated with the nonwoven fabric. The cushioning material P may be manufactured from the web W in this state.

[0049] The nonwoven fabric used for lamination is preferably made of fibers such as polylactic acid, cellulose, or regenerated cellulose. This, along with the raw materials contained in Web W, promotes a reduction in environmental impact.

[0050] A humidifier 130 may be placed downstream of the deposition section 100 to spray water onto the web W on the mesh belt 122 for humidification. This suppresses the scattering of fibers, binders, and other materials contained in the web W. Alternatively, a water-soluble additive may be added to the water used for humidification, allowing the additive to impregnate the web W in parallel with the humidification process.

[0051] The web W is transported downstream by the mesh belt 122, detached from the mesh belt 122, and drawn into the dancer roller 141. The dancer roller 141 is provided to ensure processing time for the downstream primary molding. Specifically, since the primary molding process following the deposition process is a batch process, the dancer roller 141 is moved up and down to ensure processing time for the primary molding process for the web W continuously supplied from the deposition section 100. The web W passes through the dancer roller 141 to the primary molding section 150.

[0052] The primary molding process is performed in the primary molding section 150. In the primary molding process, the web W is heated and pressurized to form a continuous sheet-like cushioning material P. The primary molding section 150 is a heating press device and comprises an upper substrate 152 and a lower substrate 151. The upper substrate 152 and the lower substrate 151 pressurize the web W between them and heat the web W with a built-in heater.

[0053] The web W is compressed from above and below by pressure, increasing its density, and the binder melts upon heating, wetting and spreading between the fibers. When heating ends and the resin solidifies in this state, the fibers are bonded together by the binder. In the primary molding process, a continuous process using a heating roller or the like may be used.

[0054] The pressurizing and heating conditions in the primary molding section 150 are appropriately adjusted depending on the desired density of the cushioning material P and the melting point of the resin binder. While not particularly limited, the pressurizing conditions are, for example, 0.1 MPa or higher, and the heating conditions are, for example, 90°C or higher. In the primary molding section 150, the web W becomes a continuous sheet-like cushioning material P, which then proceeds to the cutting section 160.

[0055] The cutting unit 160 performs the cutting process. The cutting unit 160 cuts the continuous sheet-like cushioning material P into single-sheet and plate-like cushioning material P. Although not shown in the illustration, the cutting unit 160 includes a vertical blade and a horizontal blade.

[0056] The vertical blade cuts the cushioning material P in a direction aligned with the direction of travel of the continuous sheet-like cushioning material P. The horizontal blade cuts the cushioning material P in a direction intersecting the direction of travel of the continuous sheet-like cushioning material P. As a result, roughly rectangular, plate-shaped cushioning material P is produced and placed in the tray 170.

[0057] In the secondary molding process, after the primary molding process, recesses are formed in predetermined areas of the plate-shaped cushioning material P by applying pressure. Specifically, a compression molding machine is used to form the recesses. As described above, the recesses are shaped to correspond to the three-dimensional shape of the packaged object. The conformability to the mold during compression molding is influenced by the mechanical strength of the cushioning material P. This mechanical strength is influenced by the morphology and dispersion of the fibers in the cushioning material P. In addition, protrusions may be formed along with the recesses. Note that in Figures 3 to 8, which are referenced in the following description, the -Z direction is not limited to the vertical direction.

[0058] As shown in Figure 7, in the conventional plate-shaped cushioning material P3, multiple fibers F are oriented substantially along a plane perpendicular to the Z-axis. Furthermore, entanglement between fibers F is minimal, and interference between fibers F is infrequent. These characteristics are derived from the manufacturing method, which involves lamination using a carding machine.

[0059] As shown in Figure 8, when the cushioning material P3 is compressed in the -Z direction using a mold M, the area around the region in contact with the mold M collapses significantly. This is because the compressive force of the mold M is dispersed and propagated to the surrounding area due to the orientation and morphology of the multiple fibers F of the cushioning material P3. The morphology of the fibers F referred to here includes the length-weighted average fiber length, the longest fiber length, and the aspect ratio, as described above.

[0060] Furthermore, since the cushioning material P3 is heated during compression molding, the resin in the cushioning material P3 cannot contribute to the mechanical strength during compression molding. As a result, it has been difficult to improve the mechanical strength of conventional cushioning material P3, and its conformability to the mold has tended to deteriorate.

[0061] In contrast, in the plate-shaped cushioning materials P1 and P2 of this embodiment, the orientation directions of the multiple fibers F are not easily aligned and do not tend to be biased towards a particular direction. This is because the aforementioned deposition process is carried out in air, resulting in random deposition of the fibers F compared to when the fibers are laminated using a carding machine. Furthermore, because the fiber defibration process is performed, the length-weighted average fiber length and the longest fiber length of the fibers F are shorter compared to when the fiber defibration process is not performed.

[0062] When knitted fabric is used as the raw material for fiber F, as shown in Figure 3, the cushioning material P1 contains many curved fibers F. Because knitted fabric is made by looping yarn, curved fibers F are generated from the looped parts of the yarn contained in the knitted fabric. Therefore, fibers F made from knitted fabric tend to have a smaller aspect ratio.

[0063] Furthermore, in this embodiment, the fibers F are dispersed in the air during the deposition process before being deposited to form the web W. Therefore, the fibers F are less likely to be oriented in a specific direction within the cushioning material P1. As a result, in the cushioning material P1, multiple relatively short fibers F are randomly dispersed, and curved fibers F and straight fibers F are relatively intertwined. Consequently, the mechanical strength of the cushioning material P1 is improved compared to the conventional cushioning material P3.

[0064] As shown in Figure 4, when the cushioning material P1 is compressed in the -Z direction using a mold M, almost no indentation occurs around the area in contact with the mold M. This is because the morphology and dispersion state of the multiple fibers F in the cushioning material P1 make it difficult for the compressive force of the mold M to propagate to the surrounding area. As a result, the cushioning material P1 has excellent mechanical strength and improved conformability to the mold.

[0065] When plain weave fabric is used as the raw material for fiber F, as shown in Figure 5, multiple relatively short fibers F are randomly dispersed within the cushioning material P2. Among the multiple fibers F, there are also curved fibers F, albeit in smaller quantities compared to knitted fabrics. Because plain weave fabric is woven by intersecting warp and weft threads, curved fibers F tend to be generated from the intersections of warp and weft threads in the plain weave fabric.

[0066] Furthermore, in this embodiment, the fibers F are dispersed in the air during the deposition process before being deposited to form the web W. Therefore, the fibers F are less likely to be oriented in a specific direction within the cushioning material P2. As a result, in the cushioning material P2, multiple relatively short fibers F are randomly dispersed, and the fibers F are relatively intertwined. Consequently, the mechanical strength of the cushioning material P2 is improved compared to conventional cushioning materials.

[0067] As shown in Figure 6, when the cushioning material P2 is compressed in the -Z direction using a mold M, a slight indentation occurs around the area in contact with the mold M, but the degree of indentation is less severe compared to the conventional cushioning material P3. This is because the morphology and dispersion state of the multiple fibers F in the cushioning material P3 make it difficult for the compressive force of the mold M to propagate to the surrounding area. As a result, the cushioning material P2 has superior mechanical strength and improved conformability to the mold.

[0068] As described above, a cushioning material P having a recess is manufactured. According to this embodiment, the following effects can be obtained.

[0069] A cushioning material P with improved mechanical strength can be manufactured. Specifically, since the fabric C is defibrated, the resulting fibers F tend to be relatively short. Also, since the mixture is deposited in air to form a web W, the fibers F within the web W are less likely to be oriented in a particular direction. As a result, within the cushioning material P, multiple relatively short fibers F are randomly dispersed and intertwined with each other. Therefore, compared to conventional methods where fibers F are oriented in a particular direction and laminated, the mechanical strength of the cushioning material P is improved. In other words, a method for manufacturing a cushioning material P with improved mechanical strength, and the cushioning material P itself, can be provided.

[0070] Because the cushioning material P has recesses, the packaged items can be stored and protected in these recesses. Furthermore, the mechanical strength of the cushioning material P is improved, which enhances its conformability to the mold during secondary molding processes such as compression molding. This allows for the precise formation of recesses of the desired shape.

[0071] 3. Examples and Comparative Examples The effects of the present invention will be explained in more detail below with reference to examples and comparative examples. Table 1 shows the composition of raw materials used in the manufacture, manufacturing conditions, and evaluation results for the cushioning material P of Examples 1 and 2, and the cushioning material of Comparative Example 1. In the raw material composition column of Table 1, a dash (-) indicates that no additive was used. The present invention is not limited in any way by the following examples.

[0072] [Table 1]

[0073] 3.1. Manufacturing of cushioning materials As shown in Table 1, in Example 1, 100% cotton knit fabric was used as the raw material fabric C for fiber F. Specifically, in the coarse crushing step, the knit fabric was coarsely crushed into irregularly shaped fragments with a long side of 1 mm to 30 mm using a cutter mill from Makino Sangyo Co., Ltd. Next, in the defibration step, the fragments were subjected to defibration in the same manner as in the defibration step of the above embodiment to obtain defibrated material.

[0074] Fiber F was extracted from the defibrated material, and its length-weighted average fiber length, longest fiber length, and fiber aspect ratio were determined using the method described above. As a result, the length-weighted average fiber length was 32 mm, the longest fiber length was 60 mm, and the fiber aspect ratio was 0.66.

[0075] Next, in the mixing step, the defibrated fiber F and polylactic acid as a binder were mixed in a mass ratio of 7:3 by air agitation. Then, in the deposition step, the mixture was deposited in air until it reached a basis weight of 1500 g / m². 2A web W was formed. Then, as a primary molding step, the web W was subjected to a heat press. At this time, the heating conditions were 135°C for 5 minutes, and the pressurizing conditions were such that the thickness after manufacturing was 15 mm, thereby producing the plate-shaped cushioning material P of Example 1. The method for manufacturing the plate-shaped cushioning material P of Example 1 is referred to as manufacturing method α.

[0076] In Example 2, a plain weave fabric made of 100% cotton was used as the raw material fabric C for fiber F. Specifically, in Example 2, the only difference was that the raw material for fiber F was changed; otherwise, the plate-shaped cushioning material P of Example 2 was manufactured using the same manufacturing method α as in Example 1.

[0077] Furthermore, in the fiber F extracted from the defibrated material of Example 2, the length-weighted average fiber length was 20 mm, the longest fiber length was 45 mm, and the fiber aspect ratio was 0.72.

[0078] In Comparative Example 1, commercially available absorbent cotton was used as the raw material for fiber F. Specifically, the absorbent cotton was cut into roughly rectangular strips of approximately 30 mm x 30 mm using scissors. Next, compressed air was blown onto these strips to separate the fibers F into individual fibers. The separated fibers F were then collected, and the length-weighted average fiber length, longest fiber length, and fiber aspect ratio were determined using the method described above. As a result, the length-weighted average fiber length was 28 mm, the longest fiber length was 30 mm, and the fiber aspect ratio was 0.93.

[0079] The loosened fibers F and polylactic acid as a binder were mixed in a mass ratio of 7:3 by air agitation. The mixture was then placed on a metal tray, and the fibers F were spread out while minimizing uneven distribution. This operation was repeated to form a web of layered mixture on the metal tray. The web was then subjected to a heat press in the same manner as in Example 1. At this time, the heating conditions were 135°C for 5 minutes, and the pressurizing conditions were such that the thickness after manufacturing was 15 mm, thereby producing the plate-shaped cushioning material of Comparative Example 1. The method for producing the plate-shaped cushioning material of Comparative Example 1 is referred to as manufacturing method β.

[0080] 3.2. Evaluation of cushioning materials For the cushioning material P of Examples 1 and 2, and the cushioning material of Comparative Example 1, the conformability to the mold during compression molding in the secondary molding process was investigated as an indicator of mechanical strength.

[0081] Specifically, a plate-shaped cushioning material P was cut into a square with sides of 10 cm to create a test specimen. A cylindrical iron body with a diameter of 4 cm and a height of 3 cm was placed on the center of the main surface of the test specimen, and the specimen was then placed on the bottom plate of a hydraulic press. The top and bottom plates of the hydraulic press were preheated to 135°C. Next, the test specimen and the cylindrical body were compressed from above and below using the hydraulic press, causing the cylindrical body to immerse itself 1 cm into the test specimen. After leaving it in this state for 5 minutes, the test specimen, with the cylindrical body still in place, was removed from the hydraulic press and left at room temperature of approximately 25°C.

[0082] After cooling, the cylindrical body was removed from the test specimen, and the shape of the recess in the specimen created by the cylindrical body was observed. Specifically, the angle between the bottom surface of the approximately circular recess in contact with the bottom surface of the cylindrical body and the side surface of the recess pushed into the specimen by the cylindrical body was measured. Specifically, a cross-section including the center of the bottom surface of the recess and the compression direction during compression molding was cut out. This cross-section was imaged and printed, and the angle was measured using an angle gauge. Measurements were performed on each test specimen of the examples and comparative examples, and they were evaluated according to the following criteria. Evaluation Criteria A: The above angle is 80° or greater. B: The above angle is 70° or more and less than 80°. C: The above angle is 60° or more and less than 70°. D: The above angle is less than 60°.

[0083] As shown in Table 1, the cushioning material P in Example 1 received an A rating, while the cushioning material P in Example 2 received a B rating. This indicates that in Examples 1 and 2, the mechanical strength was improved, resulting in superior conformability to the mold during compression molding. In contrast, the cushioning material in Comparative Example 1 received a D rating, indicating that it was difficult to improve mechanical strength and that its conformability to the mold was poor. [Explanation of Symbols]

[0084] C...Fabric, F...Fiber, P...Cushioning material, W...Web.

Claims

1. A defibration process in which the fabric is defibrated by a dry process to produce fibers with an aspect ratio of 0.9 or less, A mixing step of mixing a binder with the aforementioned fibers to produce a mixture, A deposition step of depositing the aforementioned mixture in air to generate a web, A primary molding step involves pressurizing and heating the web to form it, Following the primary molding process, a secondary molding process is performed to form a recess in a predetermined region by applying pressure. Equipped with, A method for manufacturing cushioning material for packaged goods, wherein the recess has a shape corresponding to the three-dimensional shape of the packaged goods.

2. A defibration step of dismantling a knitted fabric to produce fibers, A mixing step of mixing a binder with the aforementioned fibers to produce a mixture, A deposition step of depositing the aforementioned mixture in air to generate a web, A primary molding step involves pressurizing and heating the web to form it, Following the primary molding process, a secondary molding process is performed to form a recess in a predetermined region by applying pressure. Equipped with, The recess has a shape corresponding to the three-dimensional shape of the packaged object. A method for manufacturing cushioning material for packaged goods.

3. A defibration process in which the fabric is defibrated by a dry process to produce fibers with an aspect ratio of 0.9 or less, A mixing step of mixing a binder with the aforementioned fibers to produce a mixture, A deposition step of depositing the aforementioned mixture in air to generate a web, A primary molding step involves pressurizing and heating the web to form it, Following the primary molding process, a secondary molding process is performed to form a recess in a predetermined region by applying pressure. A storage step involves storing the items to be packaged in the recess to manufacture the packaging body, Equipped with, A method for manufacturing a package, wherein the recess has a shape corresponding to the three-dimensional shape of the packaged object.

4. A defibration step of disintegrating a knitted fabric to produce fibers, A mixing step of mixing a binder with the aforementioned fibers to produce a mixture, A deposition step of depositing the aforementioned mixture in air to generate a web, A primary molding step involves pressurizing and heating the web to form it, Following the primary molding process, a secondary molding process is performed to form a recess in a predetermined region by applying pressure. A storage step involves storing the items to be packaged in the recess to manufacture the packaging body, Equipped with, A method for manufacturing a package, wherein the recess has a shape corresponding to the three-dimensional shape of the packaged object.

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