Manufacturing method for molded products

Abstract

To provide a production method of a molding excellent in strength.SOLUTION: A production method of a molding comprises a deposition step of depositing a mixture of fibers and starch, a humidification step of adding water to the deposited mixture, and a molding step of obtaining a molding by heating and applying pressure to the mixture with water added. The gelatinization temperature of the starch is 60°C or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a molded article. [Background Art]

[0002] As a method for producing a molded article such as a cushioning material by recycling waste paper without using a large amount of water as in a papermaking method, there has been proposed a method for producing a molded article, comprising defibrating waste paper into a cotton-like material, adding atomized moisture thereto, and further adding a powdery or granular paste material to produce a molded article (see, for example, Patent Document 1). This method for producing a molded article has an advantage that the molded article can be produced only by using a smaller amount of water than in the papermaking method, so that energy and time consumed for dehydration, drying and the like can be saved. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. Hei 5-246465 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, in the above method for producing a molded article, simply mixing a paste material with fibers cannot achieve strong bonding between fibers, and there are cases where sufficient strength of the obtained molded article cannot be ensured. In particular, when a molded article is produced by applying a small amount of moisture to a mixture of fibers and a paste material, depending on molding conditions, regions with strong bonding between fibers and regions with weak bonding between fibers may occur in the molded article. There is a problem that the molded article is damaged starting from the regions with weak bonding, resulting in a decrease in the strength of the molded article. [Means for Solving the Problem]

[0005] A method for manufacturing a molded body includes a deposition step of depositing a mixture containing fibers and starch, a humidification step of adding water to the deposited mixture, and a molding step of heating and pressurizing the mixture to which water has been added to obtain a molded body, wherein the gelatinization temperature of the starch is 60°C or lower. [Brief explanation of the drawing]

[0006] [Figure 1] A schematic diagram showing a preferred embodiment of a binder used in a method for manufacturing molded articles. [Figure 2] A schematic side view showing the configuration of a manufacturing apparatus suitable for carrying out a method for manufacturing molded articles. [Modes for carrying out the invention]

[0007] Preferred embodiments of the present invention will be described below.

[0008] 1. Method for manufacturing molded articles The following describes each step in the manufacturing process of the molded product. Before that, however, we will explain the raw materials used in the manufacturing process of the molded product.

[0009] 1.1. Ingredients The method for manufacturing the molded article uses fibers and starch, which is a binding material that connects the fibers, as raw materials.

[0010] 1.1.1. Fibers Fibers are the main component of molded products manufactured using molded product manufacturing methods. They contribute significantly to maintaining the shape of the molded product and greatly influence its properties, such as strength.

[0011] The fibers may be composed of any material, but it is preferable that they maintain their fibrous state even when heated during the molding process.

[0012] The fiber may be a synthetic fiber composed of a synthetic resin such as polypropylene, polyester or polyurethane, but is preferably a naturally-derived fiber, i.e., a biomass-derived fiber, and more preferably a cellulose fiber.

[0013] This makes it possible to more suitably address environmental issues, save fossil reserves, and the like.

[0014] In particular, when the fiber is a cellulose fiber, the following effects can also be obtained.

[0015] That is, cellulose fiber is an abundant plant-derived natural material. By using cellulose fiber as the fiber, it is possible to more suitably address environmental issues, save fossil reserves, and the like, and this is also preferable from the viewpoints of stable supply of molded articles, cost reduction, and the like. In addition, among various fibers, cellulose fiber has particularly high theoretical strength, and is advantageous from the viewpoint of further improving the strength of the molded article.

[0016] Cellulose fiber is generally mainly composed of cellulose, but may contain components other than cellulose. Examples of such components include hemicellulose, lignin, and the like.

[0017] The fiber is preferably composed of a substance containing at least one chemical structure selected from a hydroxyl group, a carbonyl group, and an amino group.

[0018] This facilitates the formation of hydrogen bonds between the fiber and starch, which is a binding material that binds the fibers, and can improve the bonding strength between the fiber and starch. Accordingly, the strength of the entire molded article, for example, the tensile strength of a sheet-shaped molded article, can be further improved.

[0019] Further, as the cellulose fiber, one subjected to treatment such as bleaching may be used.

[0020] Further, the fibers may have been subjected to a treatment such as ultraviolet irradiation treatment, ozone treatment, or plasma treatment. This can enhance the hydrophilicity of the fibers and improve the affinity with starch, which is the binding material. More specifically, these treatments can introduce functional groups such as hydroxyl groups to the surface of the fibers, enabling more efficient formation of hydrogen bonds between the fibers and starch.

[0021] The average length of the fibers is not particularly limited, but is preferably 0.1 mm or more and 50.0 mm or less, more preferably 0.2 mm or more and 5.0 mm or less, and still more preferably 0.3 mm or more and 3.0 mm or less.

[0022] This allows further improvement in the shape stability, strength, and other properties of the produced molded article.

[0023] The average thickness of the fibers is not particularly limited, but is preferably 0.005 mm or more and 0.500 mm or less, and more preferably 0.010 mm or more and 0.050 mm or less.

[0024] This allows further improvement in the shape stability, strength, and other properties of the produced molded article. In addition, it can more effectively prevent unintended unevenness from forming on the surface of the molded article.

[0025] The average aspect ratio of the fibers, that is, the average length relative to the average thickness, is not particularly limited, but is preferably 10 or more and 1000 or less, and more preferably 15 or more and 500 or less.

[0026] This allows further improvement in the shape stability, strength, and other properties of the produced molded article. In addition, it can more effectively prevent unintended unevenness from forming on the surface of the produced molded article.

[0027] 1.1.2 Starch Starch is used as a binding material to connect fibers. Starch is a polymer material in which multiple α-glucose molecules are polymerized by glycosidic bonds. Starch contains at least one of amylose and amylopectin. Since starch is a biomass-derived raw material, using starch as a binding material can effectively address environmental issues and conserve resources.

[0028] The gelatinization temperature of the starch is 60°C or lower, preferably 55°C or lower, and more preferably 52°C or lower. By keeping the gelatinization temperature within this range, the water absorption capacity of the starch, which acts as a binder, is increased, allowing it to quickly absorb the added water. This allows for favorable gelatinization of the starch even at relatively low temperatures, resulting in excellent binding properties. In other words, it is possible to produce molded articles with sufficient strength.

[0029] Furthermore, the gelatinization temperature of the starch is preferably 30°C or higher, and more preferably 40°C or higher. This suppresses unwanted starch gelatinization inside the molded body manufacturing apparatus. Specifically, by keeping the starch gelatinization temperature within the above range, it is possible to suppress the excessive absorption of moisture by the starch in a room temperature environment. This suppresses starch gelatinization in the flow path that supplies the binder in the molded body manufacturing apparatus. As a result, it becomes possible to stably supply the binder and uniformly mix the fibers and starch. Consequently, it is possible to manufacture molded bodies with excellent strength. It also offers excellent productivity.

[0030] Natural starches used as raw materials for starch can include, for example, those derived from various plants. More specifically, they can be derived from 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 plants such as bracken and kudzu; and palms such as sago palm.

[0031] The weight-average molecular weight of the starch is preferably 50,000 to 400,000, more preferably 70,000 to 300,000, and even more preferably 80,000 to 200,000.

[0032] This allows for improved water absorption efficiency of the starch, and enables the production of molded articles with sufficient strength. More specifically, even with a small amount of added water, gelatinization by heating proceeds favorably, resulting in excellent productivity of the molded articles. Furthermore, the strength of the produced molded articles can be improved. In addition, starch with a weight-average molecular weight within the above range is less susceptible to unintended denaturation due to the addition of water.

[0033] Starch with a weight-average molecular weight within the above range has a smaller molecular weight than ordinary starch. Starch with a weight-average molecular weight controlled to a predetermined range can be suitably obtained, for example, by the following methods: After suspending natural starch in water, starch with a weight-average molecular weight controlled to a predetermined range can be obtained by treating it with sulfuric acid, hydrochloric acid, or sodium hypochlorite under conditions that prevent the starch from gelatinizing. Alternatively, starch with a weight-average molecular weight controlled to a predetermined range can be obtained by directly adding natural starch or a very small amount of volatile acid such as hydrochloric acid diluted with water, thoroughly mixing, aging, drying at a low temperature, and then heating to 120°C to 180°C. Or, for example, starch with a weight-average molecular weight controlled to a predetermined range can be suitably obtained by hydrolyzing a paste made by heating natural starch with water using an acid or enzyme.

[0034] The weight-average molecular weight of starch can be determined by measurement using gel permeation chromatography. The weight-average molecular weights shown in the examples described later are also values ​​obtained by measurement using gel permeation chromatography.

[0035] The starch is preferably starch particles C2, as shown in Figure 1, and it is preferable that the starch particles C2 are integrated with inorganic particles C3 to form composite particles C1 as described below.

[0036] The binder C10 contains starch particles C2 containing starch and inorganic particles C3, and the binder C10 also contains composite particles C1 in which the starch particles C2 and inorganic particles C3 are integrated.

[0037] In this invention, the state in which at least a portion of the inorganic particles C3 are attached to the surface of the starch particles C2, or at least a portion of the inorganic particles C3 are contained within the starch particles C2 to form a composite particle C1, is referred to as a "composite particle C1 in which starch particles C2 and inorganic particles C3 are integrated." In other words, this does not exclude the possibility that the binder C10 contains starch particles C2 and inorganic particles C3 that do not form a composite particle C1.

[0038] In the configuration shown in Figure 1, the composite particles C1 contained in the binder C10 have inorganic particles C3 attached to the surface of starch particles C2.

[0039] This creates a repulsive force between the inorganic particles C3, making it less likely for the composite particles C1 to aggregate. The arrangement of the inorganic particles C3 can be confirmed, for example, using various electron microscopes.

[0040] The composite particle C1 preferably contains starch particles C2 with an average particle size of 1.0 μm or more and 30.0 μm or less, more preferably contains starch particles C2 with an average particle size of 3.0 μm or more and 20.0 μm or less, and even more preferably contains starch particles C2 with an average particle size of 5.0 μm or more and 15.0 μm or less.

[0041] This allows for smoother moisture absorption into the starch particles C2 contained in the binder C10 during the manufacturing of the molded article, resulting in improved strength and reliability of the resulting molded article. In particular, when the starch particles C2 have an average particle size of 30.0 μm or less, the specific surface area of ​​the starch particles C2, i.e., the ratio of surface area to volume of the starch particles C2, becomes larger, resulting in excellent water absorption efficiency of the starch particles C2. Therefore, even with a small amount of moisture added, it is possible to manufacture a molded article with sufficient strength.

[0042] The composite particle C1 contains inorganic particle C3.

[0043] The average particle size of the inorganic particles C3 is preferably 1.0 nm or more and 20.0 nm or less, more preferably 3.0 nm or more and 18.0 nm or less, and even more preferably 5.0 nm or more and 10.0 nm or less.

[0044] This effectively suppresses the formation of excessive irregularities on the surface of composite particles C1, which are attached to the surface of starch particles C2 by inorganic particles C3. Therefore, when the binder C10 is mixed with the fibers, the fluidity of the composite particles C1 can be improved, and the composite particles C1 can be mixed more uniformly with the fibers. In addition, inorganic particles C3 can be attached more effectively to the surface of starch particles C2, preventing inorganic particles C3 from unintentionally detaching from the surface of starch particles C2 or unintentionally becoming embedded inside the starch particles C2. Furthermore, because the average particle size of inorganic particles C3 is between 1.0 nm and 20.0 nm, a repulsive force acts between the inorganic particles C3, suppressing aggregation of composite particles C1 and further improving the dispersibility of composite particles C1.

[0045] The binder C10 may contain inorganic particles C3 that are not attached to the starch particles C2, in other words, inorganic particles C3 that do not constitute the composite particles C1. However, the proportion of inorganic particles C3 that constitute the composite particles C1 to the total inorganic particles C3 contained in the binder C10 is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. This suppresses aggregation of the composite particles C1 and further improves the dispersibility of the composite particles C1.

[0046] The inorganic particles C3 only need to be composed primarily of inorganic materials. Furthermore, the inorganic particles C3 may have a substantially uniform composition in each part, or they may have parts with different compositions.

[0047] Examples of constituent materials for inorganic particles C3 include various metal materials, various metal compounds, various glass materials, and various carbon materials.

[0048] Examples of metallic materials include elemental metals such as Fe, Al, Cu, Ag, and Ni, as well as alloys containing at least one of these elements.

[0049] Examples of metallic compounds include metal oxides, metal nitrides, metal carbides, and metal sulfides, and more specifically, silica, alumina, zirconia, titanium oxide, magnetite, and ferrite.

[0050] Examples of glass materials include soda-lime glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass.

[0051] Examples of carbon materials include diamond, carbon fiber, carbon black, carbon nanotubes, carbon nanofibers, and fullerenes.

[0052] In particular, silica is preferred as the constituent material of inorganic particles C3. In other words, it is preferable that inorganic particles C3 are composed of materials containing silica.

[0053] This further improves the dispersibility of the composite particles C1. As a result, it is possible to effectively suppress the unintended aggregation of the binder C10 during storage or during transport of the binder C10 in the manufacturing process of molded products.

[0054] The inorganic particles C3 may consist mainly of inorganic materials, and may also contain organic materials in addition to inorganic materials.

[0055] However, the content of inorganic material in the mother particles of inorganic particle C3 is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more.

[0056] 1.2. Method for Manufacturing Molded Articles The method for manufacturing a molded body includes a deposition step of depositing a mixture containing fibers and starch, a humidification step of humidifying the deposited mixture, and a molding step of heating and pressurizing the humidified mixture to obtain a molded body. The gelatinization temperature of the starch is 60°C or lower.

[0057] This makes it possible to bond the fibers together firmly and uniformly throughout the entire molded body, enabling the production of a molded body with sufficient strength. Specifically, when obtaining a molded body by heating and pressurizing a mixture containing humidified fibers and starch, the starch functions as a binding material that bonds the fibers together. In this case, by using starch that gelatinizes at 60°C or below as the binding material, the fibers can be bonded together even when heated at a relatively low temperature. As a result, it is possible to produce a molded body with sufficient strength while suppressing fiber deterioration due to excessive heating. Furthermore, by using starch that gelatinizes at 60°C or below as the binding material, even when it is difficult to uniformly heat the mixture of fibers and starch, which is the precursor of the molded body, it is possible to suppress damage to the fibers due to overheating in the high-temperature areas, while raising the temperature in the low-temperature areas to the gelatinization temperature to gelatinize the starch, thereby firmly bonding the fibers together and uniformly bonding them throughout the entire molded body, making it possible to produce a molded body with superior strength.

[0058] 1.2.1. Deposition process In the deposition process, a mixture containing fibers and a starch-containing binder C10 is deposited in the air.

[0059] The mixing ratio of fibers to binder C10 in this process is not particularly limited, but the content of binder C10 in the mixture is preferably 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 45% by mass or less, and even more preferably 3% by mass or more and 40% by mass or less.

[0060] This makes it possible to achieve a sufficiently high fiber content in the final molded article while also improving the strength of the molded article. Furthermore, it allows for smoother transport of the binder C10 during the manufacturing process of the molded article.

[0061] In this process, the fibers mixed with the binder C10 may be pre-treated with humidification, for example, prior to the humidification process described later, i.e., the process of humidifying the mixture. Alternatively, the fibers may be humidified between the time of mixing with the binder C10 and the deposition of the resulting mixture.

[0062] In the above-mentioned cases, the water content in the fibers subjected to this process is preferably 0.1% by mass or more and 12.0% by mass or less, more preferably 0.2% by mass or more and 10.0% by mass or less, and even more preferably 0.3% by mass or more and 9.0% by mass or less.

[0063] This effectively prevents, for example, the fibers from being negatively affected by static electricity before this process, such as the fibers adhering to the walls of the manufacturing equipment for the molded body due to static electricity, and also allows for a more uniform mixing of the fibers and the binder C10.

[0064] 1.2.2. Humidification process In the humidification process, the mixture deposited in the deposition process, i.e., the mixture containing fibers and binder C10, is humidified.

[0065] This allows for excellent bonding strength between the fibers and the binder C10, as well as bonding strength between the fibers via the binder C10, in the molding process described later, resulting in a molded article with significantly superior strength. Furthermore, the molding process can be carried out under relatively mild conditions.

[0066] The method for humidifying a mixture is not particularly limited, but it is preferable to humidify it without contact with the mixture. Examples include placing the mixture in a high-humidity atmosphere, passing the mixture through a high-humidity space, spraying a mist of a water-containing liquid onto the mixture, or passing the mixture through a space where a mist of a water-containing liquid is suspended. One or more of these methods can be selected and combined. More specifically, the mixture can be humidified using various humidifiers such as evaporative or ultrasonic humidifiers. The mixture may be humidified in multiple stages during the process of manufacturing a molded body. The water-containing liquid may contain, for example, preservatives, fungicides, insecticides, etc.

[0067] The amount of water added in the humidification process is preferably 12% to 40% by mass of the total mass of the mixture, more preferably 15% to 40% by mass, and even more preferably 20% to 30% by mass.

[0068] This allows for the production of molded articles with significantly less moisture compared to conventional papermaking methods. In other words, it is possible to produce sheets with superior strength while suppressing the amount of energy, such as electricity, required to heat and dry the added moisture.

[0069] 1.2.3. Molding process In the molding process, the mixture humidified in the humidification process is heated and pressurized. This yields a molded body. The molding process may be carried out simultaneously with the humidification process.

[0070] The heating temperature of the mixture in the molding process is not particularly limited, but is preferably 60°C to 200°C, more preferably 70°C to 150°C, and even more preferably 80°C to 120°C. In this embodiment, since starch with a gelatinization temperature of 60°C or lower is used as the binder C10, the fibers can be firmly and uniformly bonded together even at relatively low heating temperatures. As a result, it becomes possible to manufacture a molded article with sufficient strength while suppressing fiber deterioration.

[0071] This process can be carried out using, for example, a heat press or a heat roller.

[0072] This effectively prevents unintended deterioration and modification of the fibers and the components of the binder C10, while allowing the binder C10 to spread more favorably on the surface of the fibers. As a result, the strength and reliability of the manufactured molded articles can be improved. It is also preferable from the viewpoint of energy saving. Furthermore, it allows for favorable gelatinization of the starch contained in the binder C10.

[0073] When the molded body is in the form of a sheet, it is preferable to heat and pressurize the mixture using a pair of heat rollers 204, as shown in Figure 2.

[0074] This allows for uniform heating and pressurization of the mixture of fibers and binder C10 when manufacturing sheet-like molded articles. As a result, the fibers can be firmly and uniformly bonded together in the molded article, making it possible to produce a molded article with superior strength.

[0075] Furthermore, it is preferable that the heating and pressurizing of the mixture in the molding process be performed simultaneously by a pair of heat rollers 204. This eliminates the need to separately provide a pressure roller for pressurizing the mixture and a heat roller 204 for heating the mixture, allowing simultaneous heating and pressurizing of the mixture using only a pair of heat rollers 204. As a result, the overall size of the molded body manufacturing apparatus can be reduced. Also, from the viewpoint of miniaturizing the molded body manufacturing apparatus and ensuring the strength of the resulting molded body, it is preferable not to apply a pressure greater than the pressure applied to the mixture by the heat rollers 204, and not to heat the mixture to a temperature higher than the temperature at which the heat rollers heat the mixture, before pressurizing and heating the mixture with the heat rollers 204.

[0076] Furthermore, when the mixture is heated and pressurized by a pair of heat rollers 204, the surface temperature of the heat rollers 204 is preferably 70°C to 140°C, more preferably 80°C to 130°C, and even more preferably 90°C to 120°C. In this embodiment, since starch with a gelatinization temperature of 60°C or lower is used as the binder C10, the fibers can be firmly and uniformly bonded together even at relatively low heating temperatures. As a result, it becomes possible to manufacture a molded article with sufficient strength while suppressing fiber deterioration.

[0077] In the molding process, it is preferable to pressurize the mixture with a pressure of 0.1 MPa to 100.0 MPa, more preferably with a pressure of 0.2 MPa to 10.0 MPa, and even more preferably with a pressure of 0.3 MPa to 8.0 MPa.

[0078] This allows for better wetting and spreading of the binder C10 on the fiber surface while suppressing fiber degradation due to pressure. As a result, the strength of the manufactured molded product can be improved.

[0079] The method for manufacturing the molded article described above can be suitably carried out, for example, using the molded article manufacturing apparatus described below.

[0080] 1.2.4. Manufacturing equipment for molded products Next, we will describe the manufacturing equipment for molded products.

[0081] Figure 2 is a schematic diagram illustrating the configuration of a manufacturing apparatus suitable for carrying out the manufacturing method of the molded article according to this embodiment. For the sake of explanation, in the following, the upper side of Figure 2 may be referred to as "up" or "upper," the lower side as "down" or "downward," the left side as "left" or "upstream," and the right side as "right" or "downstream."

[0082] In the following explanation, as an example of a molded product manufacturing apparatus, we will use a sheet manufacturing apparatus 100 that manufactures sheets as molded products.

[0083] As shown in Figure 2, the sheet manufacturing apparatus 100, which is a molded product manufacturing apparatus, includes a raw material supply unit 11, a coarse crushing unit 12, a defibration unit 13, a sorting unit 14, a first web forming unit 15, a fine division unit 16, a mixing unit 17, a loosening unit 18, a second web forming unit 19, a sheet forming unit 20, a cutting unit 21, and a stock unit 22. The sheet manufacturing apparatus 100 also includes a humidification unit 231, a humidification unit 232, a humidification unit 233, and a humidification unit 234.

[0084] The operation of each part of the sheet manufacturing apparatus 100 is controlled by a control unit (not shown).

[0085] The following describes the configuration of each part of the sheet manufacturing apparatus 100.

[0086] The raw material supply unit 11 is the part that performs the raw material supply process, supplying sheet-like material M1 to the crushing unit 12. This sheet-like material M1 is a sheet-like material containing fibers such as cellulose fibers.

[0087] The coarse crushing section 12 is the part that performs a coarse crushing process in which the sheet-like material M1 supplied from the raw material supply section 11 is coarsely crushed in air or other air. The coarse crushing section 12 has a pair of coarse crushing blades 121 and a hopper 122.

[0088] The pair of coarse crushing blades 121 rotate in opposite directions to each other, thereby coarsely crushing the sheet-like material M1 between them, i.e., cutting it into coarse fragments M2. The shape and size of the coarse fragments M2 are preferably suitable for the defibration process in the defibration section 13. For example, they are preferably small pieces with a side length of 100 mm or less, and more preferably small pieces with a length of 10 mm to 70 mm.

[0089] The hopper 122 is positioned below the pair of coarse crushing blades 121 and is, for example, funnel-shaped. This allows the hopper 122 to receive the coarse crushed pieces M2 that have been crushed and fallen by the coarse crushing blades 121.

[0090] Furthermore, a humidifying unit 231 is positioned above the hopper 122, adjacent to a pair of coarse crushing blades 121. The humidifying unit 231 humidifies the coarse crushed pieces M2 inside the hopper 122. This humidifying unit 231 is an evaporative humidifier that has a filter (not shown) containing moisture, and supplies humidified air to the coarse crushed pieces M2 by passing air through the filter. By supplying humidified air to the coarse crushed pieces M2, it is possible to control the adhesion of the coarse crushed pieces M2 to the hopper 122 and other parts due to static electricity.

[0091] The hopper 122 is connected to the defibration section 13 via a pipe 241, which is a flow path. The coarse fragments M2 collected in the hopper 122 are transported to the defibration section 13 by passing through the pipe 241.

[0092] The defibration section 13 is the part that performs a defibration process in which the coarse fragments M2 are defibrated in air or other air, that is, in a dry manner. Through the defibration process in this defibration section 13, defibrated material M3 can be produced from the coarse fragments M2. Here, "defibration" means separating the coarse fragments M2, which are made up of multiple fibers bound together, into individual fibers. The separated fibers then become the defibrated material M3. The shape of the defibrated material M3 is linear or strip-shaped. Furthermore, the defibrated material M3 may exist in a state where they are intertwined and form clumps, that is, in a state where they form so-called "clumps".

[0093] The defibration section 13, in this embodiment for example, is composed of an impeller mill having a high-speed rotating rotor and a liner located on the outer circumference of the rotor. The coarse fragments M2 that flow into the defibration section 13 are sandwiched between the rotor and the liner and defibrated.

[0094] Furthermore, the defibration unit 13 can generate an airflow, i.e., an air current, from the coarse crushing unit 12 to the sorting unit 14 by the rotation of the rotor. This allows the coarse crushed pieces M2 to be drawn into the defibration unit 13 from the pipe 241. After the defibration process, the defibrated material M3 can be sent to the sorting unit 14 via the pipe 242.

[0095] A blower 261 is installed in the middle of pipe 242. The blower 261 is an airflow generator that generates an airflow directed toward the sorting section 14. This facilitates the delivery of the defibrated material M3 to the sorting section 14.

[0096] The sorting section 14 is the part that performs a sorting process to separate the defibrated material M3 according to the length of the fibers. In the sorting section 14, the defibrated material M3 is sorted into first sorted material M4-1 and second sorted material M4-2 which is larger than the first sorted material M4-1. The first sorted material M4-1 is of a size suitable for the subsequent manufacture of the sheet S. The second sorted material M4-2 includes, for example, materials that have not been sufficiently defibrated or materials in which the defibrated fibers have excessively aggregated.

[0097] The sorting unit 14 includes a drum section 141 and a housing section 142 that houses the drum section 141.

[0098] The drum section 141 is a sieve composed of a cylindrical mesh body that rotates around its central axis. The defibrated material M3 flows into this drum section 141. As the drum section 141 rotates, the defibrated material M3 smaller than the mesh opening is sorted as the first sorted material M4-1, and the defibrated material M3 larger than the mesh opening is sorted as the second sorted material M4-2.

[0099] The first sorted item, M4-1, falls from the drum section 141.

[0100] The second sorted material M4-2 is sent to a pipe 243, which is a flow path connected to the drum section 141. The pipe 243 is connected to the drum section 141 on the opposite side, i.e., the upstream side. After passing through the pipe 243, the second sorted material M4-2 merges with the coarse fragments M2 within the pipe 241 and flows into the defibration section 13 together with the coarse fragments M2. As a result, the second sorted material M4-2 is returned to the defibration section 13 and subjected to defibration processing together with the coarse fragments M2.

[0101] Furthermore, the first sorted material M4-1 from the drum section 141 disperses into the air as it falls toward the first web forming section 15, which is a separation section located below the drum section 141. The first web forming section 15 is the part that performs the first web forming process, which forms the first web M5 from the first sorted material M4-1. The first web forming section 15 has a mesh belt 151 which is a separation belt, three tension rollers 152, and a suction section 153.

[0102] The mesh belt 151 is an endless belt on which the first sorted material M4-1 accumulates. This mesh belt 151 is wrapped around three tension rollers 152. The rotational drive of the tension rollers 152 then transports the first sorted material M4-1 on the mesh belt 151 downstream.

[0103] The first sorted material M4-1 is larger than the mesh opening of the mesh belt 151. As a result, the passage of the first sorted material M4-1 through the mesh belt 151 is restricted, and it can therefore accumulate on the mesh belt 151. Furthermore, as the first sorted material M4-1 accumulates on the mesh belt 151 and is transported downstream along with the mesh belt 151, it forms a layered first web M5.

[0104] Furthermore, the first sorted material M4-1 may contain dust and other particles. Dust and particles may be mixed in with the sheet material M1 when it is supplied from the raw material supply unit 11 to the crushing unit 12. These dust and particles are smaller than the mesh opening of the mesh belt 151. As a result, the dust and particles pass through the mesh belt 151 and fall further down.

[0105] The suction unit 153 can draw in air from below the mesh belt 151. This allows dust and dirt that has passed through the mesh belt 151 to be drawn in along with the air.

[0106] The suction unit 153 is connected to the recovery unit 27 via a pipe 244, which is a flow path. Dust and dirt sucked up by the suction unit 153 are collected in the recovery unit 27.

[0107] A pipe 245, which serves as a flow path, is further connected to the recovery section 27. A blower 262 is installed in the middle of the pipe 245. The operation of this blower 262 generates suction force in the suction section 153. This promotes the formation of the first web M5 on the mesh belt 151. This first web M5 is formed from dust and dirt that has been removed. The dust and dirt are then passed through the pipe 244 by the operation of the blower 262 and reach the recovery section 27.

[0108] The housing section 142 is connected to the humidifying section 232. The humidifying section 232 is composed of an evaporative humidifier similar to the humidifying section 231. As a result, humidified air is supplied into the housing section 142. This humidified air can humidify the first sorted material M4-1, and thus it is possible to suppress the first sorted material M4-1 from adhering to the inner wall of the housing section 142 due to electrostatic force.

[0109] A humidification unit 235 is located downstream of the sorting unit 14. The humidification unit 235 consists of an ultrasonic humidifier that sprays water. This supplies moisture to the first web M5, thereby adjusting the moisture content of the first web M5. This moisture adjustment suppresses the adhesion of the first web M5 to the mesh belt 151 due to electrostatic force. As a result, the first web M5 is easily detached from the mesh belt 151 at the position where the mesh belt 151 is folded back by the tension roller 152.

[0110] A subdivision section 16 is located downstream of the humidification section 235. The subdivision section 16 is the part that performs the subdivision process of dividing the first web M5 that has been separated from the mesh belt 151. The subdivision section 16 has a rotatably supported propeller 161 and a housing section 162 that houses the propeller 161. The first web M5 can be divided by being caught in the rotating propeller 161. The divided first web M5 becomes a subdivision body M6. The subdivision body M6 then descends within the housing section 162.

[0111] The housing section 162 is connected to the humidifying section 233. The humidifying section 233 is composed of an evaporative humidifier similar to the humidifying section 231. As a result, humidified air is supplied into the housing section 162. This humidified air also helps to suppress the adhesion of the fragments M6 to the propeller 161 and the inner wall of the housing section 162 due to electrostatic force.

[0112] A mixing section 17 is located downstream of the subdivision section 16. The mixing section 17 is the part that performs the mixing process of mixing the subdivided material M6 with the aforementioned binder C10. This mixing section 17 includes a binder supply section 171, a pipe 172 which is a flow path, and a blower 173.

[0113] The pipe 172 connects the housing portion 162 of the subdivision portion 16 and the housing portion 182 of the loosening portion 18, and is a flow path through which the mixture M7 of the subdivision material M6 and the binder C10 passes.

[0114] A binder supply unit 171 is connected to the middle of the pipe 172. The binder supply unit 171 has a screw feeder 174. By rotating this screw feeder 174, the binder C10 can be supplied to the pipe 172. The binder C10 supplied to the pipe 172 is mixed with the fractionated material M6 to form a mixture M7.

[0115] Furthermore, the binder supply unit 171 may contain, along with the binder C10, a coloring agent for coloring the fibers, an agglomeration inhibitor for suppressing the aggregation of fibers and the binder C10, a flame retardant for making the fibers and other materials less flammable, and so on.

[0116] Furthermore, a blower 173 is installed in the middle of the pipe 172, downstream of the binder supply section 171. The blower 173 can generate an airflow directed towards the loosening section 18. This airflow can agitate the subdivided material M6 and the binder C10 within the pipe 172. As a result, the mixture M7 can flow into the loosening section 18 with the subdivided material M6 and binder C10 uniformly dispersed. In addition, the subdivided material M6 in the mixture M7 is loosened as it passes through the pipe 172, becoming finer fibers.

[0117] The loosening section 18 is the part that performs a loosening process in the mixture M7, which involves loosening the intertwined fibers. The loosening section 18 has a drum section 181 and a housing section 182 that houses the drum section 181.

[0118] The drum section 181 is a sieve composed of a cylindrical mesh body that rotates around its central axis. The mixture M7 flows into this drum section 181. As the drum section 181 rotates, fibers and other materials smaller than the mesh opening of the mixture M7 can pass through the drum section 181. In the process, the mixture M7 is loosened.

[0119] The housing section 182 is connected to the humidifying section 234. The humidifying section 234 is composed of an evaporative humidifier similar to the humidifying section 231. As a result, humidified air is supplied into the housing section 182. This humidified air humidifies the inside of the housing section 182, thereby suppressing the adhesion of the mixture M7 to the inner wall of the housing section 182 due to electrostatic force.

[0120] The mixture M7 loosened in the drum section 181 disperses into the air and falls toward the second web forming section 19 located below the drum section 181. The second web forming section 19 is the part that performs the second web forming process, in which a second web M8 is formed from the mixture M7. In this embodiment, the second web forming process is a deposition process in which the mixture containing fibers and binder C10 is deposited in the air. The second web forming section 19 has a mesh belt 191 which is a separation belt, a tensioning roller 192, and a suction section 193.

[0121] The mesh belt 191 is an endless belt on which the mixture M7 is deposited. This mesh belt 191 is wrapped around four tension rollers 192. The rotational drive of the tension rollers 192 then conveys the mixture M7 on the mesh belt 191 to the downstream side.

[0122] Furthermore, most of the mixture M7 on the mesh belt 191 is larger than the mesh opening of the mesh belt 191. This prevents the mixture M7 from passing through the mesh belt 191, and thus allows it to accumulate on the mesh belt 191. In addition, as the mixture M7 accumulates on the mesh belt 191, it is transported downstream along with the mesh belt 191, forming a layered second web M8.

[0123] The suction unit 193 can draw air from below the mesh belt 191. This allows the mixture M7 to be drawn onto the mesh belt 191, thereby promoting the accumulation of the mixture M7 on the mesh belt 191.

[0124] A pipe 246, which serves as a flow path, is connected to the suction unit 193. A blower 263 is installed in the middle of this pipe 246. The operation of this blower 263 generates suction force in the suction unit 193.

[0125] A humidification unit 236 is located downstream of the loosening unit 18. The humidification unit 236 is the part that performs the humidification process described above. The humidification unit 236 is composed of an ultrasonic humidifier similar to the humidification unit 235. This allows moisture to be supplied to the second web M8, thereby adjusting the moisture content of the second web M8. This moisture adjustment makes it possible to achieve a suitable bonding strength between the fibers and the binder C10 in the sheet S, which is the final molded product.

[0126] Furthermore, humidification can suppress the electrostatic attraction of the second web M8 to the mesh belt 191. As a result, the second web M8 can be easily detached from the mesh belt 191 at the position where the mesh belt 191 is folded back by the tension roller 192.

[0127] A sheet forming section 20 is located downstream of the second web forming section 19. The sheet forming section 20 is the part that performs the sheet forming process, which is a molding process that forms a sheet S from the second web M8. This sheet forming section 20 has a pressurizing section 201 and a heating section 202.

[0128] The pressurizing section 201 has a pair of calender rollers 203, which can pressurize the second web M8 between them. This increases the density of the second web M8. The second web M8 is then conveyed toward the heating section 202. One of the pair of calender rollers 203 is a driven roller driven by a motor (not shown), and the other is a driven roller.

[0129] The heating section 202 has a pair of heat rollers 204. By passing the second web M8 between the pair of heat rollers 204, the second web M8 can be heated and pressurized. Due to the heating and pressurizing using the pair of heat rollers 204, the binder C10 melts within the second web M8, and the fibers bond together via the molten binder C10. This forms a sheet S as a molded body. By heating the second web M8 with the pair of heat rollers 204, the second web M8 can be heated and pressurized uniformly, and a sheet S with excellent strength can be manufactured.

[0130] The surface temperature of the heat roller 204 is preferably between 70°C and 140°C. This allows for strong and uniform bonding of fibers at a relatively low heating temperature. As a result, it becomes possible to manufacture molded articles with sufficient strength while suppressing fiber degradation.

[0131] The heat roller 204 is preferably pressurized with a pressure of 0.1 MPa to 100.0 MPa, more preferably with a pressure of 0.2 MPa to 10.0 MPa, and even more preferably with a pressure of 0.3 MPa to 8.0 MPa.

[0132] This allows the binder C10 to be more effectively wetted and spread across the surface of the fibers. As a result, the strength of the molded article produced can be improved.

[0133] Of the pair of heat rollers 204, one is a driving roller driven by a motor (not shown), and the other is a driven roller.

[0134] A cutting section 21 is located downstream of the sheet forming section 20. The cutting section 21 is the part that performs the cutting process for cutting the sheet S. This cutting section 21 has a first cutter 211 and a second cutter 212.

[0135] The first cutter 211 cuts the sheet S in a direction intersecting the conveying direction of the sheet S.

[0136] The second cutter 212 is located downstream of the first cutter 211 and cuts the sheet S in a direction parallel to the conveying direction of the sheet S.

[0137] By cutting with the first cutter 211 and the second cutter 212 in this manner, a sheet S of the desired size as a molded body is obtained. This sheet S is then conveyed further downstream and stored in the stock section 22.

[0138] 1.3. Molded body Next, we will describe the molded body.

[0139] The molded article is manufactured using the molded article manufacturing method described above. This makes it possible to provide a molded article with excellent strength.

[0140] Preferably, the fibers and starch-containing binder C10 contained in the molded article satisfy the same conditions as described above.

[0141] The shape of the molded body is not particularly limited and may be any shape, such as a sheet, block, sphere, or three-dimensional solid; however, the molded body according to this embodiment is preferably in the form of a sheet. Here, "sheet" refers to a thickness of 30 μm or more and 30 mm or less, with a density of 0.05 g / cm³. 3 More than 1.50g / cm 3 This refers to a molded body formed in the following manner.

[0142] This allows the molded body to be suitably used as a recording medium, for example. Furthermore, by using the apparatus described above, manufacturing can be done more efficiently.

[0143] When the molded article according to the present invention is a sheet-shaped recording medium, its thickness is preferably 30 μm or more and 30 mm or less.

[0144] This allows the molded body to be used more favorably as a recording medium. Furthermore, by using the apparatus described above, manufacturing can be done more efficiently.

[0145] If it is a sheet-shaped recording medium, its density is 0.6 g / cm³. 3 More than 0.9g / cm 3 The following is preferable. This allows the molded body to be used more favorably as a recording medium.

[0146] The molded article only needs to be manufactured by applying the above-described method for manufacturing a molded article to at least a portion of it, and may also have other parts. Furthermore, it may be manufactured by performing a post-processing step after the steps described in the method for manufacturing a molded article.

[0147] The applications of the molded body are not particularly limited and include, for example, recording media, liquid absorbers, cushioning materials, soundproofing materials, etc.

[0148] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto.

[0149] For example, in the embodiments described above, the case in which the binder C10 contains composite particles C1 in which inorganic particles C3 are attached to the surface of starch particles C2 was mainly explained. However, the binder C10 may not contain the composite particles C1 as described above, as long as it contains starch. Also, although the form of starch was mainly described as starch particles C2, the binder may not contain starch particles C2 as long as it contains starch.

[0150] Furthermore, each component of the sheet manufacturing apparatus 100 can be replaced with any other component capable of performing a similar function. Additionally, any additional components may be added.

[0151] 2. Examples Next, embodiments of the present invention will be described.

[0152] 2.1. Preparation of binder 2.1.1. Preparation of raw starch 1-5 Starch with a weight-average molecular weight of 1.3 million (manufactured by Nippon Denki Chemical Co., Ltd., G-800) was suspended in water, and sulfuric acid was reacted under conditions that prevented the starch from gelatinizing. The mixture was thoroughly mixed and stirred for 12 hours. After drying at 50°C for 24 hours to reduce the moisture content to 10% by mass or less, the mixture was heated at 120-180°C to obtain a paste-like starch. Subsequently, the paste-like starch was washed with water, freeze-dried, and then coarsely ground to obtain raw material starch 1 with a weight-average molecular weight of 100,000. The gelatinization temperature of raw material starch 1 was 51°C. Furthermore, starch with a weight-average molecular weight of 1.3 million (manufactured by Nippon Denki Chemical Co., Ltd., G-800) was processed in the same manner as when raw material starch 1 was produced, except that the processing conditions (concentration of sulfuric acid, stirring time) were changed, to obtain raw material starch 2 (gelatinization temperature 42°C), raw material starch 3 (gelatinization temperature 57°C), raw material starch 4 (gelatinization temperature 34°C), and raw material starch 5 (gelatinization temperature 68°C).

[0153] A Rigaku Thermo Plus EVO DSC8231 differential scanning calorimeter was used to measure the gelatinization temperature of each raw starch. Specifically, a solution was prepared by mixing raw starch and deionized water in a mass ratio of 1:2, and this solution was sealed in a pressure-resistant aluminum pan to serve as the measurement sample. Next, the measurement sample was placed in the above apparatus, and differential calorimetry was performed at a heating rate of 10°C per minute. In the obtained DSC curves, the temperature at which the curve began to shift endothermally relative to the baseline was read as the gelatinization temperature.

[0154] 2.1.2. Preparation of starch particles 1-1~1-3, 2-1, 3-1, 4-1, and 5-1 Raw starch 1 was crushed at a processing pressure of 4 bar using a fluidized bed counter-jet mill (counter jet mill AFG-R, manufactured by Hosokawa Micron Corporation) to obtain starch particle C2, which had an average particle size of 10 μm, specifically starch particle 1-1. Raw starches 2-5 were subjected to the same treatment as raw starch 1 to obtain starch particles 2-1, 3-1, 4-1, and 5-1, respectively. Furthermore, raw starch 1 was treated in the same manner as when starch particle 1 was produced, except for a change in the processing pressure during crushing, to obtain starch particle 1-2 with an average particle size of 4 μm (processing pressure 6 bar) and starch particle 1-3 with an average particle size of 20 μm (processing pressure 2 bar).

[0155] 2.1.3. Preparation of composite particles (Preparation Example 1) 99 parts by mass of starch particles 1-1 and 1 part by mass of fumed silica (HM-30S, manufactured by Tokuyama Corporation) as inorganic particle C3 were packed into a Henschel mixer (FM mixer FM 20C / I, manufactured by Nippon Coke Industries Co., Ltd.) and mixed at a frequency of 60 Hz for 10 minutes. After that, the mixture was sieved using a sieve with a mesh size of 30 μm to prepare binder C10 of Preparation Example 1, which contains composite particle C1 in which starch particles C2 and fumed silica as inorganic particle C3 are integrated.

[0156] (Preparation Examples 2-7) The binder C10 for Preparation Examples 2 to 7 was prepared in the same manner as in Preparation Example 1, except that the starch particles C2 and inorganic particles C3 were configured as shown in Table 1.

[0157] [Table 1]

[0158] 2.1.4. Manufacturing of Sheets as Molded Products (Example 1) In this example, a sheet was manufactured as a molded body using the binder C10 from Preparation Example 1 described above.

[0159] A modified sheet manufacturing machine 100 (Seiko Epson PaperLab® A-8000) was prepared, which was modified to allow humidification of the sheet after forming and before pressurization. As the fiber source, commercially available copy paper (Fuji Xerox GR70-W) on which business documents were printed using an inkjet printer was used as the sheet material M1.

[0160] Next, the sheet-like material M1 was supplied to the raw material supply unit 11 of the sheet manufacturing apparatus 100, and the binder prepared in binder preparation example 1 was supplied to the binder supply unit 171. The sheet manufacturing apparatus 100 was then operated, and the material underwent the following processes: crushing, defibration, sorting, first web formation, cutting, mixing, loosening, second web formation (a lamination process), humidification, sheet formation (a molding process), and cutting, to produce an A4-sized sheet as a molded body. The basis weight of the obtained sheet was 90 g / m². 2 That was the case.

[0161] At this time, the final molded sheet was adjusted so that it contained 10 parts by mass of binder for every 90 parts by mass of fiber as raw material. In addition, the conditions for heating and pressurizing during the molding process were set to a heat roller 204 temperature of 110°C, a pressurizing force of 70 MPa, and a heating and pressurizing time of 15 seconds.

[0162] (Examples 2-10, Comparative Example 1) An A4-sized sheet was manufactured as a molded body in the same manner as in Example 1, except that the binder C10 was as shown in Table 2 and the molding conditions were as shown in Table 2.

[0163] 2.2. Evaluation 2.2.1. Strength of the molded body From the molded sheets produced in each of the above examples and comparative examples, 100 mm x 20 mm strips were cut out, and the breaking strength was measured along the longitudinal direction of each strip. A Shimadzu Autograph AGS-1N was used to measure the breaking strength at a tensile speed of 20 mm / sec. The specific tear strength was calculated from this and evaluated according to the following criteria. A higher specific tear strength indicates superior strength.

[0164] A: The specific tear strength is 25 Nm / g or higher. B: The specific tear strength is 20 Nm / g or more and less than 25 Nm / g. C: Specific tear strength is 15 Nm / g or more and less than 20 Nm / g. D: The specific tear strength is 10 Nm / g or more and less than 15 Nm / g. E: Specific tear strength is less than 10 Nm / g. The results are shown in Table 2.

[0165] [Table 2]

[0166] As is clear from Table 2, Examples 1 to 10, which produced molded articles using the method for producing molded articles according to the present invention, showed excellent results, with the resulting molded articles having a specific tear strength of D or higher. In contrast, Comparative Example 1 used starch whose gelatinization temperature was outside the range specified in the present invention, but unsatisfactory results were not obtained.

[0167] Furthermore, the strength of the molded body obtained in Example 10 is lower compared to Example 1 and others, which were manufactured under the same molding conditions. This is thought to be because the binder of Preparation Example 6 used in Example 10 has higher water absorption than the binder of Preparation Example 1 used in Example 1 and others, causing starch gelatinization in the flow path that supplies the binder in the molded body manufacturing apparatus, which reduced the transportability of the binder. [Explanation of Symbols]

[0168] C10...binder, C1...composite particles, C2...starch particles, C3...inorganic particles, 201...pressure section, 202...heating section, 203...calender roller, 204...heat roller.

Claims

1. A deposition process in which a mixture containing fibers and starch is deposited, A humidification step of adding water to the deposited mixture, The process includes a molding step of heating and pressurizing the mixture to which water has been added to obtain a molded body, The gelatinization temperature of the aforementioned starch is 60°C or lower. In the aforementioned starch, at least a portion of the inorganic particles adhere to the surface of the starch particles, and together with the inorganic particles form composite particles. The proportion of the inorganic particles that constitute at least some of the composite particles to the inorganic particles is 70% by mass or more. A method for manufacturing a molded product.

2. The method for producing a molded article according to claim 1, wherein the heating temperature of the mixture in the molding step is 60°C or more and 200°C or less.

3. The method for manufacturing a molded article according to claim 1 or 2, wherein the molding step involves heating and pressurizing the mixture using a pair of heat rollers.

4. The method for manufacturing a molded article according to claim 2 or 3, wherein the molding step involves pressurizing the mixture with a pressure of 0.2 MPa or more and 10.0 MPa or less.

5. A method for producing a molded article according to any one of claims 1 to 4, wherein the gelatinization temperature of the starch is 30°C or higher.

6. The method for manufacturing a molded article according to any one of claims 1 to 5, wherein the amount of water added in the humidification step is 12% by mass or more and 40% by mass or less relative to the total mass of the mixture.

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