JP2024042249A - Sheet manufacturing device - Google Patents

Abstract

To smoothly manufacture a sheet.SOLUTION: A sheet manufacturing device has an accumulation section to form a web by accumulating materials including fibers by an air flow, a humidification section to apply moisture from one surface side of the web, and a pressurization section to form a sheet by pressurizing the humidified web at a pressurization position. The pressurization section has a first roller coming in contact with the one surface of the web at the pressurization position and a second roller coming in contact with the other surface of the web at the pressurization position. The web is conveyed so that the one surface of the web comes in contact with the surface of the first roller across a predetermined length from the pressurization position as a starting point. The first roller has a heating mechanism. The first roller heats the web while the one surface of the web comes in contact with the surface of the first roller.SELECTED DRAWING: Figure 3

Description

The present invention relates to a sheet manufacturing apparatus.

Conventionally, as shown in Patent Document 1, a defibration section defibrates a material to be defibrated in the atmosphere, a mixing section mixes an additive containing a resin to the defibrated material in the atmosphere, and a defibration section that defibrates the defibrated material in the atmosphere. A sheet manufacturing apparatus is known that includes a humidity control section that controls the humidity of a mixture of fibers and additives, a pressure section that pressurizes the controlled mixture, and a heating section that heats the pressurized mixture. It is being

JP 2015-137437 A

However, the above-mentioned apparatus requires a resin as a binder in order to produce a sheet with sufficient strength. In recent years, there has been a demand for a method for producing sheets that have sufficient strength without using resin.

The sheet manufacturing apparatus includes a deposition section that deposits fiber-containing material using an airflow to form a web, a humidification section that applies moisture from one side of the web, and a pressurizing section to the humidified web. a first roller that contacts the one side of the web at the pressing location, and a first roller that contacts the one side of the web at the pressing location; a second roller in contact with the other surface, and the web is conveyed such that the one surface of the web contacts the surface of the first roller over a predetermined length starting from the pressurizing point, The first roller has a heating mechanism, and the first roller heats the web while the one surface of the web is in contact with the surface of the first roller.

FIG. 1 is a schematic diagram showing the configuration of a sheet manufacturing device. FIG. 3 is a schematic diagram showing the configuration of a pressurizing section. FIG. 4 is a schematic diagram showing a state in which a web is wrapped around a pressure unit.

First, the configuration of the sheet manufacturing apparatus 1 will be explained. The sheet manufacturing apparatus 1 is an apparatus that forms sheets S.
As shown in FIG. 1, the sheet manufacturing apparatus 1 includes, for example, a supply section 10, a coarse crushing section 11, a defibrating section 20, a sorting section 40, a first web forming section 45, a rotating body 49, It includes a mixing section 50, a depositing section 60, a web conveying section 80, a humidifying section 90, a pressing section 100, and a cutting section 120. Furthermore, the sheet manufacturing apparatus 1 includes a control section (processor) that controls the drive mechanism of each of the above sections.

The supply section 10 supplies raw materials to the coarse crushing section 11 . The supply unit 10 is, for example, an automatic input unit for continuously inputting raw materials into the coarse crushing unit 11. The raw material supplied by the supply unit 10 is a material containing various fibers.

The fibers are not particularly limited, and a wide variety of fiber materials can be used. Examples of fibers include natural fibers (animal fibers, vegetable fibers), chemical fibers (organic fibers, inorganic fibers, organic-inorganic composite fibers), and the like. More specifically, the fibers include fibers made of cellulose, silk, wool, cotton, hemp, kenaf, flax, ramie, jute, Manila hemp, sisal hemp, softwood, hardwood, etc., and these may be used alone. However, they may be mixed as appropriate and used, or they may be used as regenerated fibers that have been purified.

Examples of raw materials for fibers include pulp, used paper, old cloth, and the like. Further, the fibers may be subjected to various surface treatments. Further, the material of the fiber may be a pure substance or may be a material containing a plurality of components such as impurities and other components. Further, as the fiber, a defibrated material obtained by dry defibrating waste paper, pulp sheet, etc. may be used.

The length of the fiber is not particularly limited, but it is a single independent fiber, and the length of the fiber along the longitudinal direction is 1 μm or more and 5 mm or less, preferably 2 μm or more and 3 mm or less, and more preferably 3 μm or more and 2 mm. It is as follows.

In the sheet manufacturing apparatus 1, since moisture is applied in the humidifying section 90, the mechanical strength of the sheet S to be formed can be increased by using fibers capable of forming hydrogen bonds. Such fibers include cellulose.

The content of fibers in the sheet S is, for example, 50% by mass or more and 99.9% by mass or less, preferably 60% by mass or more and 99% by mass or less, and more preferably 70% by mass or more and 99% by mass or less. Such a content can be achieved by blending when forming a mixture.

The coarse crushing section 11 shreds the raw material supplied by the supply section 10 into small pieces in air such as the atmosphere. The shape and size of the strips are, for example, several cm square. The coarse crushing section 11 has a coarse crushing blade 12, and the coarse crushing blade 12 can cut the input raw material. As the coarse crushing section 11, for example, a shredder is used. The raw material shredded by the crushing section 11 is received by a hopper 14 and then transferred to the defibrating section 20 via a pipe 15.

The defibrating section 20 defibrates the raw material shredded by the coarse crushing section 11. Here, "defibrating" refers to loosening a raw material made up of a plurality of bound fibers into individual fibers. The defibrating section 20 also has the function of separating substances such as resin particles, ink, toner, and anti-bleeding agent attached to the raw material from the fibers.

The material that has passed through the defibrating section 20 is referred to as a "defibrated material." In addition to the unraveled fibers, the "defibrated material" includes resin particles separated from the fibers during unraveling, coloring agents such as ink and toner, anti-bleeding materials, paper strength enhancers, etc. It may also contain agents. The shape of the loosened defibrated material is string-like. The loosened defibrated material may exist in a state where it is not intertwined with other loosened fibers, that is, in an independent state, or it may be entangled with other loosened defibrated materials to form a lump. It may exist in a state, that is, in a state where it forms lumps.

The defibration section 20 performs defibration in a dry manner. Here, processing such as defibration in air such as the atmosphere rather than in a liquid is referred to as a dry process. As the defibrating section 20, for example, an impeller mill is used. The defibrating section 20 has a function of generating an airflow that sucks the raw material and discharges the defibrated material. Thereby, the defibrating section 20 can suction the raw material from the inlet 22 along with the air flow using the air flow generated by itself, perform the defibration process, and transport the defibrated material to the discharge port 24. The defibrated material that has passed through the defibrating section 20 is transferred to the sorting section 40 via the pipe 16. Note that the airflow for conveying the defibrated material from the defibration unit 20 to the sorting unit 40 may be generated by using the airflow generated by the defibration unit 20, or an airflow generation device such as a blower may be provided to generate the airflow. You may use it.

The sorting section 40 introduces the defibrated material defibrated by the defibrating section 20 through the introduction port 42 and sorts it according to the length of the fibers. The sorting section 40 includes, for example, a drum section 41 and a housing section 43 that accommodates the drum section 41. As the drum section 41, for example, a sieve is used. The drum section 41 has a mesh, and contains fibers or particles smaller than the opening size of the mesh, that is, the first sorted material passing through the mesh, fibers, unfibrillated pieces, and clumps larger than the opening size of the mesh, In other words, it is possible to separate the second sorted material that does not pass through the screen. For example, the first sorted material is transferred to the deposition section 60 via the pipe 17. The second sorted material is returned to the defibrating section 20 from the discharge port 44 via the pipe 18. Specifically, the drum section 41 is a cylindrical sieve that is rotationally driven by a motor. As the mesh for the drum portion 41, for example, a wire mesh, expanded metal made by stretching a metal plate with cuts, or punched metal made by forming holes in a metal plate using a press or the like is used.

The first web forming section 45 conveys the first sorted material that has passed through the sorting section 40 to the pipe 17 . The first web forming section 45 includes, for example, a mesh belt 46, a tension roller 47, and a suction mechanism 48.

The suction mechanism 48 can suck the first sorted material that has passed through the opening of the sorting section 40 and is dispersed in the air onto the mesh belt 46 . As a result, the first sorted material is deposited on the moving mesh belt 46.

The first sorted material that has passed through the opening of the sorting section 40 is deposited on the mesh belt 46 . The mesh belt 46 is stretched by a tension roller 47, and has a configuration that allows air to pass through it but not easily through the first sorted material. The mesh belt 46 moves as the tension roller 47 rotates. A web V is formed on the mesh belt 46 by continuously moving the mesh belt 46 and continuously piling up the first sorted material that has passed through the sorting section 40 .

The suction mechanism 48 is provided below the mesh belt 46. The suction mechanism 48 can generate a downward airflow. The first sorted material dispersed in the air by the sorting section 40 can be sucked onto the mesh belt 46 by the suction mechanism 48 . Thereby, the discharge speed from the sorting section 40 can be increased.

The web V passes through the sorting section 40 and the first web forming section 45 and is formed into a soft and swollen state containing a large amount of air. The web V deposited on the mesh belt 46 is introduced into the pipe 17 and conveyed to the depositing section 60.

The rotating body 49 cuts the web V. In the illustrated example, the rotating body 49 has a base 49a and a protrusion 49b protruding from the base 49a. The protrusion 49b has, for example, a plate-like shape. In the illustrated example, four protrusions 49b are provided, and the four protrusions 49b are provided at equal intervals. By rotating the base 49a in the direction R, the protrusion 49b can rotate about the base 49a. By cutting the web V with the rotating body 49, for example, fluctuations in the amount of fibers supplied to the deposition section 60 per unit time can be reduced.

The rotating body 49 is provided near the first web forming section 45 . In the illustrated example, the rotating body 49 is provided near the tension roller 47a located on the downstream side in the path of the web V. The rotating body 49 is provided at a position where the protrusion 49b can come into contact with the web V, but is not in contact with the mesh belt 46 on which the web V is deposited. Thereby, it is possible to suppress the mesh belt 46 from being worn out by the protrusion 49b. The shortest distance between the protrusion 49b and the mesh belt 46 is, for example, 0.05 mm or more and 0.5 mm or less. This is the distance at which the web V can be cut without the mesh belt 46 being damaged.

The mixing section 50 mixes the first sorted material (fiber) that has passed through the sorting section 40 and starch as a binder. The mixing unit 50 includes a starch supply unit 52 that supplies starch, a pipe 54 that conveys the first sorted material and the starch, and a blower 56. In the illustrated example, starch is supplied from the starch supply section 52 to the tube 54 via the hopper 19. Tube 54 is connected to tube 17.

In the mixing section 50, an air current is generated by a blower 56, and the first sorted material and starch can be mixed and conveyed in the tube 54. Note that the mechanism for mixing the first sorted material and the starch is not particularly limited, and may be one that stirs with a blade that rotates at high speed, or one that uses rotation of a container like a V-type mixer. It's okay.

As the starch supply section 52, a screw feeder, a disk feeder, or the like is used.

The starch supplied from the starch supply unit 52 is a polymer in which a plurality of α-glucose molecules are polymerized through glycosidic bonds. Starch may be linear or may contain branches.

Starch derived from various plants can be used. Starch sources include cereals such as corn, wheat, and rice; beans such as broad beans, mung beans, and red beans; tubers such as potato, sweet potato, and tapioca; wild plants such as dogtooth violets, bracken, and kudzu; and palms such as sago palm.

Furthermore, processed starch or modified starch may be used as the starch. Processed starches include acetylated adipic acid cross-linked starch, acetylated starch, oxidized starch, sodium octenyl succinate starch, hydroxypropyl starch, hydroxypropylated phosphate cross-linked starch, phosphorylated starch, phosphate esterified phosphate cross-linked starch, Examples include urea phosphorylated esterified starch, sodium starch glycolate, and high amylose corn starch. Moreover, as the modified starch, dextrin obtained by processing or modifying starch can be suitably used.

In the sheet manufacturing apparatus 1, by using starch as a binder, the environmental impact can be reduced compared to when synthetic resin is used. In addition, by adding moisture to the fibers (first sorted material) containing starch and then pressurizing and heating the fibers, at least one of bonding between the fibers due to gelatinization of the starch and hydrogen bonding between the fibers occurs, and the sheet S can have sufficient strength. Note that if the sheet S can have sufficient strength only through hydrogen bonding between the fibers, the sheet S can also be manufactured without using starch. When manufacturing the sheet S without using starch, the sheet manufacturing apparatus 1 does not need to be equipped with a starch supply unit 52.

The starch content in the sheet S is, for example, 0.1% by mass or more and 50% by mass or less, preferably 1% by mass or more and 40% by mass or less, and more preferably 1% by mass or more and 30% by mass or less. Such a content can be achieved by blending when forming a mixture.

In addition to starch, the starch supply section 52 may contain, depending on the type of sheet S being manufactured, a colorant for coloring the fibers, an aggregation inhibitor for inhibiting aggregation of the fibers and aggregation of the starch, and a flame retardant for making the fibers, etc. less flammable. The mixture that has passed through the mixing section 50 is transferred to the deposition section 60 via the pipe 54.

The deposition section 60 introduces the mixture that has passed through the mixing section 50 through an inlet 62, loosens entangled fibers, and makes them fall while being dispersed in the air. Thereby, the deposition section 60 can deposit the mixture on the second web forming section 70 with good uniformity.

The deposition section 60 includes, for example, a drum section 61 and a housing section 63 that accommodates the drum section 61. As the drum section 61, a rotating cylindrical sieve is used. The drum section 61 has a net, and drops fibers or particles smaller than the opening size of the mesh, which are 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.

Note that the "sieve" of the drum section 61 does not need to have the function of sorting out specific objects. That is, the "sieve" used as the drum section 61 means one equipped with a screen, and the drum section 61 may filter out all of the mixture introduced into the drum section 61.

The deposition section 60 includes a second web forming section 70 . The second web forming section 70 forms a web W by depositing the mixture that has passed through the drum section 61. The second web forming section 70 includes, for example, a first mesh belt 72, a tension roller 74, and a suction mechanism 76.

The mixture that has passed through the opening of the deposition section 60 is deposited on the first mesh belt 72 . The first mesh belt 72 is stretched by a tension roller 74, and has a structure that allows air to pass through but not easily to pass the mixture. The first mesh belt 72 moves as the tension roller 74 rotates. The web W is formed on the first mesh belt 72 by continuously moving the first mesh belt 72 and continuously piling up the mixture that has passed through the deposition section 60 .

The suction mechanism 76 is provided below the first mesh belt 72. The suction mechanism 76 can generate a downward airflow. The mixture dispersed in the air by the drum section 61 can be sucked onto the first mesh belt 72 by the suction mechanism 76 . Thereby, the discharge speed from the deposition section 60 can be increased. Furthermore, the suction mechanism 76 can form a downflow in the falling path of the mixture, and can prevent fibers and starch from becoming entangled while falling.

As described above, by passing through the deposition section 60, a soft and swollen web W containing a large amount of air is formed.

A web conveying section 80 is arranged on the downstream side of the first mesh belt 72 in the conveying direction of the web W. The web transport section 80 peels the web W on the first mesh belt 72 from the first mesh belt 72 and transports it toward the pressure section 100 .
As shown in FIG. 2, the web conveyance section 80 includes a second mesh belt 81 as a conveyance belt, a plurality of rollers 82, and a suction mechanism 83 as a suction section. The second mesh belt 81 is stretched by a plurality of rollers 82 and is configured to allow air to pass through. The second mesh belt 81 is configured to be rotatably driven by the rotation of the roller 82 . The suction mechanism 83 is arranged at a position facing the web W with the second mesh belt 81 interposed therebetween. The suction mechanism 83 includes an intake fan (not shown), and generates an upward (+Z direction) airflow in the second mesh belt 81 by the suction force of the intake fan. The web W is sucked by this airflow.

Thereby, the web W can be peeled off from the first mesh belt 72 and the other surface Wb, which is the upper surface of the web W peeled off from the first mesh belt 72, can be brought into contact with the second mesh belt 81. Then, the other surface Wb of the web W contacts the second mesh belt 81, and the web W is conveyed while being held.

A humidifying section 90 is arranged below the web conveying section 80. The humidifier 90 is arranged to face the second mesh belt 81. The humidifying unit 90 applies moisture from one side Wa side which is the lower surface of the web W in contact with the second mesh belt 81 . The humidifier 90 applies humidified air (for example, water vapor or mist) to the web W as moisture.

As shown in FIG. 2, the humidifying unit 90 includes a container 91 capable of storing water, and a piezoelectric vibrator 92 disposed at the bottom of the container 91. A discharge port 93 is formed at the top of the container 91 to discharge humidified air. The container 91 is arranged so that the discharge port 93 faces one side Wa of the web W. By driving the piezoelectric vibrator 92, ultrasonic waves are generated in the water, and mist (humidified air) is generated in the container 91. The generated mist is applied toward one side Wa of the web W via the outlet 93 of the container 91. By applying moisture from below the web W, water droplets will not fall onto the web W even if dew condensation occurs in the humidifying section 90 or its vicinity. That is, for example, when moisture is applied to the web W from above, the moisture may adhere to the humidifying section 90 or its vicinity, fall as water droplets, and the water droplets may adhere to the web W. In this case, the application of moisture to the web W becomes non-uniform. However, in this embodiment, the falling of water droplets, etc. is suppressed, and the quality of the sheet S can be avoided from being affected.

The suction mechanism 83 is arranged at a position facing the humidifying section 90 with the second mesh belt 81 interposed therebetween. The suction mechanism 83 sucks the mist discharged from the humidifying section 90. The mist discharged from the discharge port 93 is sucked into the suction mechanism 83 arranged opposite to the discharge port 93. Thereby, the mist is sucked into the suction mechanism 83 via the web W, so that moisture can be applied to the web W in the thickness direction.

The moisture content of the web W to which moisture has been added in the humidifying section 90 is, for example, 12% by mass or more and 40% by mass or less. This web moisture content allows hydrogen bonds to be effectively formed between the fibers, thereby increasing the strength of the sheet S.

A pressure unit 100 is arranged downstream of the web conveyance unit 80 and the humidification unit 90. The web W to which moisture has been applied is conveyed to the pressurizing section 100.

The pressurizing section 100 pressurizes the humidified web W to form a sheet S. The pressure unit 100 includes a first roller 101 that contacts one side Wa of the web W, and a second roller 102 that contacts the other side Wb of the web W. The web W is sandwiched between the first roller 101 and the second roller 102 and pressurized to form the sheet S. Note that the detailed configuration of the pressurizing section 100 will be described later.
A cutting section 120 is arranged downstream of the pressurizing section 100. The sheet S formed by the pressing section 100 is conveyed to the cutting section 120.

The cutting section 120 cuts the sheet S formed by the pressing section 100. In the illustrated example, the cutting section 120 includes a first cutting section 122 that cuts the sheet S in a direction intersecting the conveying direction of the sheet S, and a second cutting section 124 that cuts the sheet S in a direction parallel to the conveying direction. , has. The second cutting section 124 cuts the sheet S that has passed through the first cutting section 122 .
Through the above steps, a cut sheet S of a predetermined size is formed. The cut sheet S is discharged to the receiving section 130.

Next, the detailed configuration of the pressurizing section 100 will be explained. First, the form of the nip portion Np (pressure location) in the pressure section 100 will be described.
As described above, this embodiment realizes the sheet manufacturing apparatus 1 that forms the sheet S using starch as a binder. Here, in the sheet manufacturing process using starch, it is necessary to add moisture to the web W containing starch, and since the amount of moisture in the web W is relatively large, for example, wrinkles etc. may occur when pressurized. This easily occurs, making it difficult to maintain the smoothness of the sheet S.
Therefore, the pressure unit 100 of this embodiment is configured to be able to form a smooth sheet S. This will be explained in detail below.

As shown in FIGS. 2 and 3, the pressure section 100 includes a first roller 101 and a second roller 102. As shown in FIGS. Each rotation axis of the first roller 101 and the second roller 102 is arranged along the direction along the X-axis. The dimensional length of the first roller 101 and the second roller 102 along the X axis is longer than the dimensional length of the transported web W along the X axis. Thereby, the first roller 101 and the second roller 102 can nip the entire area of the web W along the X axis.

In this embodiment, the surface of the first roller 101 is configured to be harder than the surface of the second roller 102. Specifically, the first roller 101 is made of metal, and the second roller 102 is made of metal and rubber covering the surface thereof.
More specifically, the first roller 101 includes a hollow core metal 111 such as aluminum, iron, stainless steel, or the like. The surface of the first roller 101 contains PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene/hexafluoropropylene copolymer), and ETFE (tetrafluoroethylene). A surface layer 112 made of a fluororesin such as ethylene/ethylene copolymer) or a silicone resin is provided. By providing the surface layer 112, the mold releasability with respect to the web W (sheet S) can be improved. Furthermore, wear and damage to the core metal 111 can be suppressed.
The second roller 102 includes a hollow core metal 114 such as aluminum, iron, stainless steel, or the like. The surface of the core bar 114 is covered with an elastic layer 115 made of silicone rubber, urethane rubber, or the like. The hardness of the elastic body is preferably Asker C 30 or more and 70 or less, more preferably Asker C 40 or more and 60 or less. The thickness of the elastic layer is preferably 1 mm or more and 10 mm or less, more preferably 1 mm or more and 5 mm or less. Further, the surface of the elastic layer 115 is made of PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene/hexafluoropropylene copolymer), ETFE (tetrafluoropropylene copolymer), or It is covered with a surface layer 116 made of a fluororesin layer (such as ethylene/ethylene copolymer) or a tube containing a fluororesin. By providing the surface layer 116, the releasability from the web W (sheet S) can be improved. Furthermore, wear and damage to the elastic layer 115 can be suppressed.

By applying pressure to the web W by the first roller 101 and the second roller 102, the web W becomes thinner and the fiber density within the web W increases. The pressure applied to the web W by the first roller 101 and the second roller 102 is preferably 0.1 MPa or more and 15 MPa or less, more preferably 0.2 MPa or more and 10 MPa or less, and even more preferably 0.4 MPa or more and 8 MPa or less. If the pressure is within this range, deterioration of the fibers can be suppressed, and a sheet S with good strength can be manufactured again using the defibrated material obtained by defibrating the manufactured sheet S as a raw material.

Further, the first roller 101 and the second roller 102 of this embodiment each have built-in heaters 113 and 117 (for example, a halogen heater) for heating as heating mechanisms. The temperatures of the first roller 101, the second roller 102, and the heaters 113, 117 are acquired by the temperature detection unit, and the driving of the heaters 113, 117 is controlled based on the acquired temperatures. Thereby, it becomes possible to maintain each surface temperature of the first roller 101 and the second roller 102 at a predetermined temperature. For example, the surface temperature of the first roller 101 is preferably 100°C or more and 130°C or less, and the surface temperature of the second roller 102 is preferably 80°C or more and 100°C or less.

Since the pressurizing section 100 of this embodiment simultaneously pressurizes and heats the web W, it is possible to improve the productivity of the sheet S. Furthermore, the configuration of the sheet manufacturing apparatus 1 can be simplified. Moreover, the water contained in the web W evaporates after the temperature rises, and the thickness of the web W becomes thinner, increasing the fiber density. The temperature of water and starch increases due to the heat, and the fiber density increases due to the pressure. In addition, the starch gelatinizes, and then the water evaporates, and a plurality of fibers are bonded to each other via the gelatinized starch. Furthermore, water evaporates due to heat and fiber density increases due to pressure, so that a plurality of fibers are bound together by hydrogen bonds.

Here, when moisture is added to the web W containing starch and fibers, it is necessary to form the sheet S by reliably binding the fibers in the web W in the pressurizing section 100. This is because if water remains in the web W, the binding of the fibers will be insufficient and wrinkles etc. will easily occur in the sheet S.
Therefore, in the nip portion Np where the web W is sandwiched between the first roller 101 and the second roller 102, it is necessary to ensure a sufficient nip width Nw. The nip portion Np refers to a pressurizing location where the web W is pressed by the first roller 101 and the second roller 102, and the nip width Nw is the dimension in the conveyance direction of the web W at the nip portion Np. That is, the nip width Nw is the length dimension from the nip start position to the nip end position of the web W between the first roller 101 and the second roller 102. The nip width Nw is formed to have a substantially constant dimension along the X axis of the nip portion Np.

By ensuring a sufficient nip width Nw, the heating and pressurizing time of the web W is ensured, so that the fibers contained in the sheet S are reliably bonded, and a sheet S with better mechanical strength can be formed. In order to ensure the nip width Nw, for example, a configuration using soft rollers with rubber surfaces for both the first roller 101 and the second roller 102 is considered. This ensures the nip width Nw by the elastic deformation of each soft roller. However, since both soft rollers elastically deform, the pressure variation in the nip portion Np tends to increase, and wrinkles are likely to occur. Therefore, a smooth sheet S cannot be formed. On the other hand, if metal rollers (hard rollers) are used for both the first roller 101 and the second roller 102, elastic deformation does not occur, so the nip width Nw cannot be sufficiently ensured, and the pressurizing and heating time of the web W cannot be ensured, resulting in insufficient bonding of the fibers.

According to this embodiment, when the web W is nipped between the first roller 101 and the second roller 102 which have different hardnesses, the surface of the second roller 102 is stably indented by the pressing pressure of the first roller 101. It becomes a state. This maintains a constant nip width Nw and stabilizes the pressure within the nip portion Np. Since the web W can be heated and pressurized in this state, the fibers in the web W can be reliably bound, and a smooth sheet S can be formed.

In addition, since moisture is applied from one side Wa of the web W, the one side Wa has a larger amount of moisture in the thickness direction of the web W than the other side Wb. Therefore, when the web W is nipped, the moisture can be moved from the one side Wa to the other side Wb by the heating of the first roller 101 made of a hard metal with good thermal conductivity. As a result, the web W is pressurized and heated in a state in which the moisture has spread throughout the entire thickness direction, so that the uniformity of the strength within the sheet S can be improved.
Furthermore, since the web W is heated to a high temperature on the side of the first roller 101, steam in the web W is likely to spread to the other side Wb that contacts the lower temperature side of the second roller 102. Also, by heating the one side Wa of the web W, which has more moisture, to a higher temperature, the diffusion of moisture to the other side Wb is promoted, improving the heating efficiency.

In addition, in the case where both the first roller 101 and the second roller 102 are configured to use soft rollers, thickness unevenness of the sheet S occurs due to expansion and contraction of the surface of each soft roller at the nip portion Np. According to this embodiment, one side Wa of the web W containing a large amount of water easily sticks to the harder first roller 101 side, and the web W can be nipped while following the first roller 101 side. At this time, one surface Wa of the web W is pinned on the first roller 101 side, and the other surface Wb is nipped on the second roller 102 side in a slipping state, so that a smooth sheet S can be formed.

Moreover, the surface of the first roller 101 of this embodiment has unevenness. In this case, the surface roughness measured by the surface roughness meter is preferably 2 μm or more and 8 μm or less, and more preferably 3 μm or more and 6 μm or less in terms of Ra (arithmetic mean roughness). Further, Rz (maximum height) is preferably 15 μm or more and 70 μm or less, more preferably 25 μm or more and 50 μm or less. The unevenness on the surface of the first roller 101 is formed by, for example, blasting or thermal spraying.

Since the surface of the first roller 101 has very minute irregularities, it is possible to reduce the difference in surface quality between the first surface Sa (the surface corresponding to one surface Wa of the web W) and the second surface Sb (the surface corresponding to the other surface Wb of the web W) of the sheet S while ensuring the smoothness of the sheet S. In detail, when the web W is pressed between the first roller 101 and the second roller 102, the thickness of the high fiber density portion of the web W is large, and the thickness of the low fiber density portion is small. Here, if both the first roller 101 and the second roller 102 are soft rollers, the unevenness in the web W occurs almost evenly on the one surface Wa and the other surface Wb because both rollers elastically deform. As a result, the difference in surface quality between the first surface Sa and the second surface Sb of the sheet S is reduced. However, in this embodiment, since one of the first rollers 101 is made of metal, it does not elastically deform, and when nipped, the unevenness in the web W is biased toward the second roller 102 side having a soft surface. Therefore, the second surface Sb of the sheet S on the second roller 102 side becomes a relatively rough surface, and the first surface Sa of the sheet S on the first roller 101 side becomes a smooth surface, resulting in a difference in surface quality between the first surface Sa and the second surface Sb of the sheet S. Therefore, by forming minute irregularities on the surface of the first roller 101, the first surface Sa of the sheet S on the first roller 101 side also becomes a relatively rough surface. Therefore, the difference in surface quality between the first surface Sa and the second surface Sb of the sheet S can be reduced. In addition, when the first surface Sa and the second surface Sb of the sheet S are touched with the fingers, the texture of the first surface Sa and the second surface Sb of the sheet S is similar, and the sense of incongruity is reduced. In addition, for example, when an image is formed on the sheet S by a printer or the like, the first surface Sa and the second surface Sb can maintain the same image quality.

Next, the winding manner of the web W in the pressing unit 100 will be described.
As described above, in the present embodiment, a sheet manufacturing process using starch is adopted. Here, since moisture is added to the web W by the humidifying unit 90, deformation and breakage easily occur, making handling difficult.
Therefore, the pressurizing unit 100 of the present embodiment is configured to be able to stably handle the web W. This will be specifically described below.

The pressure section 100 includes a first roller 101 that contacts one surface Wa of the web W at the nip section Np (pressure location), and a second roller 102 that contacts the other surface Wb of the web W at the nip section Np. .
As shown in FIG. 3, the web W is conveyed such that one surface Wa of the web W contacts the surface of the first roller 101 over a predetermined length starting from the nip portion Np. Then, while one surface Wa of the web W is in contact with the surface of the first roller 101, the first roller 101 heats the web W. That is, the web W is heated in the nip part Np and the wrapping area Ta where it is wrapped around the first roller 101 over a predetermined length from the nip part Np. The sheet S is formed by passing through the wrapping area Ta.

In this embodiment, since moisture is applied from one side Wa of the web W, the amount of moisture is greater than that on the other side Wb, so the one side Wa of the web W sticks more easily. Utilizing this characteristic, the web W can be stably handled by conveying the web W with one side Wa attached to the first roller 101 (wrapped around it). In addition, since the one side Wa side of the web W having a large moisture content is wound around the first roller 101, it is possible to heat the web W efficiently.

In addition, moisture still remains inside the web W discharged from the nip portion Np, making the web W prone to deformation and breakage. In this embodiment, the first roller 101 is provided with a winding region Ta downstream of the nip portion Np in the transport direction, thereby improving transportability of the web W and ensuring drying.
In addition, by wrapping the web W around the first roller 101 located below the web W being transported due to its own weight, the transport posture of the web W after the nip portion Np is stabilized, and deformation, etc., can be suppressed.

A third roller 103 is provided at a position facing the first roller 101 and downstream of the nip portion Np in the transport direction of the web W. Furthermore, a pair of transport rollers 118 is arranged downstream of the third roller 103. The web W (sheet S) is transported downstream by driving the transport roller pair 118 . The web W passing through the wrapping area Ta from the nip portion Np is peeled off from the first roller 101 at a predetermined position, contacts the lower part of the third roller 103, and is conveyed downstream.
Since the web W is conveyed via the third roller 103, the predetermined length of the web W wound around the first roller 101 (winding area Ta) can be kept constant.

Furthermore, since the surface of the first roller 101 has unevenness, the pinning effect (anchor effect) due to the unevenness suppresses deformation and breakage of the web W after the nip portion Np, and prevents the web W from being deformed or broken during heating of the wrapping area Ta. It is also possible to suppress the occurrence of waviness in the web W due to shrinkage.

Here, the first roller 101 is a driving roller, and the second roller 102 is a driven roller. Since the first roller 101 on the side around which the web W is wound is a driving roller, the transport speed of the web W and the tension on the web W are stable, and a smooth sheet S can be formed.

Further, in this embodiment, the diameter of the first roller 101 is larger than the diameter of the second roller 102. The diameter of the first roller 101 is, for example, 110 mm or more and 150 mm or less, and the diameter of the second roller 102 is, for example, 80 mm or more and less than 110 mm.
By increasing the diameter of the first roller 101, the wrapping area Ta can be secured. That is, the heating time for the web W can be secured. The winding dimension of the web W in the winding region Ta is, for example, about 1/8 to 1/2, preferably about 1/8 to 1/4 of the outer peripheral dimension of the first roller 101. Note that the setting of the wrapping area Ta can be changed as appropriate depending on the heating conditions of the heater 113 and the like.
Since the web W is conveyed following the larger roller circumferential surface, the curl of the sheet S upon completion of drying is reduced.
Further, by making the second roller 102 smaller, the configuration of the pressure section 100 can be made smaller.

DESCRIPTION OF SYMBOLS 1... Sheet manufacturing apparatus, 10... Supply part, 11... Crushing part, 20... Defibration part, 40... Sorting part, 50... Mixing part, 52... Starch supply part, 60... Deposition part, 70... Second web formation Part, 80... Web conveyance part, 90... Humidification part, 91... Container, 92... Piezoelectric vibrator, 93... Discharge port, 100... Pressure part, 101... First roller, 102... Second roller, 103... Third Roller, 111... Core bar, 112... Surface layer, 113... Heater, 114... Core bar, 115... Elastic layer, 116... Surface layer, 117... Heater, 118... Transport roller pair, 120... Cutting section, 130... Receiving section , W...web, Wa...one side, Wb...other side, S...sheet, Sa...first side, Sb...second side, Np...nip portion, Nw...nip width, Ta...wrapping area.

Claims (6)

a depositing section for depositing fiber-containing material by airflow to form a web;
a humidifying unit that applies moisture from one side of the web;
a pressurizing section that presses the humidified web at a pressurizing point to form a sheet;
The pressure unit includes a first roller that contacts the one surface of the web at the pressure location, and a second roller that contacts the other surface of the web at the pressure location,
The web is conveyed such that the one side of the web contacts the surface of the first roller over a predetermined length starting from the pressurized point,
The first roller has a heating mechanism, and the first roller heats the web while the one side of the web is in contact with the surface of the first roller. sheet manufacturing equipment. The sheet manufacturing apparatus according to claim 1,
A sheet manufacturing apparatus characterized in that the first roller is made of metal. The sheet manufacturing apparatus according to claim 1,
A sheet manufacturing apparatus characterized in that a diameter of the first roller is larger than a diameter of the second roller. The sheet manufacturing apparatus according to claim 1,
a third roller located at a position opposite to the first roller and provided downstream from the pressurizing point in the conveyance direction of the web;
A sheet manufacturing apparatus characterized in that the web peeled off from the first roller contacts the third roller. The sheet manufacturing apparatus according to claim 2,
A sheet manufacturing apparatus characterized in that the surface of the first roller has irregularities. The sheet manufacturing apparatus according to claim 1,
a starch supply unit that supplies starch for binding the fibers;
A sheet manufacturing device comprising: a mixing section that mixes the starch and the fibers.

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