Method for manufacturing a shaped body and a jointing material

Abstract

Provided is a method for manufacturing a molded body that improves the strength of a molded body obtained by dry molding, and a bonded material. The method for manufacturing a molded body includes: a second sheet formation step of allowing a mixture (M7) containing a fiber and a bonding material to be accumulated in air, the bonding material containing starch and an alkali metal salt; a humidification step of giving water to the mixture (M7); and a sheet formation step of allowing the mixture (M7) to which water is given to be heated and pressurized to obtain a sheet (S), the content of the alkali metal salt in the bonding material being 2.0% by mass or less relative to the total mass of the starch.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a molded article and the materials used for bonding it. Background Technology

[0002] A method for manufacturing a sheet-like molded article comprising fibers and high-molecular-weight polysaccharides such as starch as a binding material for the fibers has been known for a long time. For example, Patent Document 1 discloses a starch-based paper strength enhancer that uses starch with a low average degree of polymerization as the main component.

[0003] However, the starch-based paper strength enhancer described in Patent Document 1 has the following problem: even when used in dry forming with a small amount of water, it is difficult to improve the strength of the molded article. This is because the fibrils of the fibers cannot contribute to interfiber bonding in a small amount of water. Furthermore, the insufficient interfiber bonding force caused by this cannot be compensated by the low molecular weight starch-based paper strength enhancer described in Patent Document 1. Therefore, in order to obtain a molded article with sufficient strength using a small amount of water, as in the manufacturing method of the molded article of the present invention, it is necessary to use a starch-based paper strength enhancer with an appropriate molecular weight. In order to obtain such a starch-based paper strength enhancer, it is necessary to appropriately control the molecular weight of the starch. Therefore, it is more effective to perform treatment such as hydrolysis of starch using acid. Here, when molecular weight control is achieved by acid treatment, the following problems sometimes occur.

[0004] In detail, during the acid treatment of starch, alkali metal hydroxides are sometimes added to neutralize the acid. If alkali metal salts generated during the neutralization reaction remain in the starch, the gelatinization temperature can become unstable, making it difficult to manage. Since the gelatinization temperature of starch affects the strength of the molded article, improving its strength becomes challenging. Therefore, a method for manufacturing molded articles that improves the strength of the molded article compared to existing technologies is sought.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-115960 Summary of the Invention

[0006] The method for manufacturing a molded article includes: a stacking step in which a mixture comprising fibers and a binding material is stacked in air, the binding material comprising starch and an alkali metal salt; a humidification step in which water is supplied to the mixture; and a molding step in which the mixture, to which water has been supplied, is heated and pressurized to obtain a molded article, wherein the content of the alkali metal salt in the binding material is less than 2.0% by mass relative to the total mass of the starch.

[0007] The binding material includes a binding material comprising starch, which binds fibers together by being given water, and an alkali metal salt, wherein the content of the alkali metal salt in the binding material is less than 2.0% by mass relative to the total mass of the starch. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating the structure of the composite used in the manufacturing method of the molded body according to the embodiment.

[0009] Figure 2 A flowchart illustrating the manufacturing method of the shaped object.

[0010] Figure 3 This is a schematic diagram showing the structure of the manufacturing apparatus used in the manufacturing method of the molded body. Detailed Implementation

[0011] In the embodiments described below, examples are given of a bonding material for dry forming and a method for manufacturing a sheet-like molded body using the bonding material, and the description is based on the accompanying drawings. For ease of illustration, the sizes of the components are slightly different from actual dimensions. Furthermore, in this specification, dry forming refers to a method that uses a relatively small amount of water compared to wet forming, such as wet sheet forming. The amount of water used will be described later.

[0012] 1. Complex

[0013] like Figure 1 As shown, the composite C10 of this embodiment includes composite particles C1, which contain inorganic oxide particles C3 integrally within the binder particles C2, which are particles containing starch as a binder material. Composite C10 is an example of a binder material for dry forming in this invention. Composite C10 functions as a binder material that bonds the fibers together when manufacturing a shaped article containing fibers.

[0014] Here, the inclusion of inorganic oxide particles C3 in the binding material particles C2 in an integral manner means that at least a portion of the inorganic oxide particles C3 are located on the surface or inside the binding material particles C2. In the composite C10, in addition to including composite particles C1, it may also separately include binding material particles C2 and inorganic oxide particles C3 that do not form composite particles C1.

[0015] In particular, in composite particles C1, when inorganic oxide particles C3 are attached to the surface of bonding material particles C2, there will be repulsive forces between the inorganic oxide particles C3.

[0016] As a result, the C2 binding material particles become less likely to aggregate, thus suppressing the uneven distribution of C2 binding material particles in the molded body and thereby improving the strength of the molded body. The state of the inorganic oxide particles C3 in the C2 binding material particles can be observed, for example, using a scanning electron microscope.

[0017] 1.1. Composite particles

[0018] In the composite particle C1, one or more inorganic oxide particles C3 are attached to the surface of a bonding material particle C2. Preferably, multiple inorganic oxide particles C3 are attached to the surface of a bonding material particle C2. This promotes the suppression of aggregation of the bonding material particle C2.

[0019] The average particle size of the composite particles C1 is preferably 1.0 μm or more and 100.0 μm or less, more preferably 2.0 μm or more and 70.0 μm or less, and even more preferably 3.0 μm or more and 50.0 μm or less. This can further promote the above-mentioned effect.

[0020] In this specification, the average particle size refers to the 50% volumetric particle size distribution. The average particle size is measured using the dynamic light scattering method or laser diffraction method described in JIS Z8825. Specifically, a commercially available particle size analyzer that uses dynamic light scattering as its measurement principle, such as the MICROTRAC UPA from Nikkiso Corporation, can be used. The average particle size of the starch is measured using the aforementioned apparatus after dispersion in a solvent such as water.

[0021] The content of composite particles C1 in composite C10 is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, relative to the total mass of composite C10. This suppresses uneven distribution of composite particles C1.

[0022] 1.1.1. Combining material particles

[0023] The starch in the binding material C2 is gelatinized by heating after being given water. This gelatinization of the starch binds the fibers in the mixture, described later as a material used to form the body, together with each other.

[0024] Starch forms non-covalent bonds, such as hydrogen bonds, with fibers, especially cellulose fibers with functional groups such as hydroxyl groups. Therefore, starch provides good coating properties for fibers, thereby improving the strength of molded articles.

[0025] Starch is a high molecular weight compound formed by the polymerization of multiple α-glucose molecules through glycosidic bonds. Starch includes at least one of amylose and amylopectin.

[0026] While the sources of starch are not specifically limited, examples include grains such as corn, wheat, and rice; legumes such as peas, broad beans, mung beans, and adzuki beans; tubers such as potatoes, sweet potatoes, and cassava; wild herbs such as wild ferns, bracken, and kudzu; and palm trees such as coconut palms. Because starch is derived from natural substances, it is more effective in reducing carbon dioxide emissions compared to petroleum-based sources, and it also exhibits superior biodegradability.

[0027] Processed starch or modified starch can also be used as a starch material. Examples of processed starch include acetylated adipic acid crosslinked starch, acetylated starch, oxidized starch, sodium octenyl succinate starch, hydroxypropyl starch, hydroxypropyl distarch phosphate, monostarch phosphate, phosphorylated distarch phosphate, urea phosphate starch, sodium starch glycolate, and high-amino corn starch.

[0028] Examples of modified starches include α-starch, dextrin, lauryl polydextrose, cationic starch, thermoplastic starch, and carbamate starch. Dextrin is preferably a material obtained by processing or modifying starch.

[0029] The gelatinization temperature of starch is preferably 30°C or higher and 60°C or lower, more preferably 35°C or higher and 55°C or lower, and even more preferably 40°C or higher and 52°C or lower. Therefore, even with a relatively small amount of water and a relatively low heating temperature, starch gelatinization is readily achieved. This is therefore preferable for manufacturing molded articles achieved by dry forming, thereby further improving the strength of the molded article during dry forming. Furthermore, the method for measuring the gelatinization temperature of starch will be described later.

[0030] The gelatinization temperature of starch is related to the molecular chain length, i.e., the average molecular weight. Therefore, when the gelatinization temperature of starch exceeds 60°C, it is preferable to adjust the gelatinization temperature by breaking down the high molecular weight chains and reducing their molecular weight. Methods for breaking down the high molecular weight chains of starch include acid treatment, enzyme treatment, oxidant treatment, and physical treatments. In particular, acid treatment is preferred for ease of processing. That is, it is preferable to use acid-treated starch that has been hydrolyzed and had its average molecular weight adjusted through acid treatment.

[0031] The average molecular weight of the starch, for example, by weight-average molecular weight, is preferably 50,000 or more and 400,000 or less. This improves the water absorption of the binding material particles C2, thereby reducing the amount of water required during the manufacture of the molded article. The weight-average molecular weight of the starch can be determined by GPC (Gel Permeation Chromatography).

[0032] Starch that has undergone acid treatment sometimes contains salts such as alkali metal salts. In this case, the binding material includes starch and alkali metal salts. Specifically, acids such as hydrochloric acid and sulfuric acid are used in the acid treatment. Moreover, after adjusting the average molecular weight with acid, the acid is neutralized using aqueous solutions such as sodium hydroxide and potassium hydroxide. At this time, alkali metal salts such as sodium chloride, potassium chloride, and sodium sulfate are generated from the acid from the acid treatment and the base from the neutralization treatment.

[0033] Although the alkali metal salts generated during acid treatment can be reduced by subsequent washing during neutralization, some remain in the prior art, causing instability in the gelatinization temperature. Specifically, differential scanning calorimetry (DSC) is used to measure the gelatinization temperature of starch. If DSC is performed on starch containing a high amount of alkali metal salts, the endothermic peak representing the gelatinization temperature in the obtained DSC curve is prone to deformation and branching. This makes it difficult to accurately determine the gelatinization temperature, thus making its management challenging. Furthermore, during the molding process, the gelatinization process achieved by the binding material particles C2 is unstable, becoming a major cause of reduced strength in the molded body.

[0034] Therefore, additional cleaning treatments are performed to reduce the alkali metal salt content in the binder to 2.0% by mass or less relative to the total mass of starch. This content is preferably 1.5% by mass or less relative to the total mass of starch, and more preferably 1.0% by mass or less. This makes the endothermic peak value representing the gelatinization temperature of starch in differential scanning calorimetry stable and clear, thereby enabling management of the gelatinization temperature. Known cleaning methods such as water washing filtration and ultrafiltration can be used to reduce the alkali metal salt content in the starch.

[0035] The average particle size of the combined material particles C2 is preferably 1.0 μm or more and 30.0 μm or less, more preferably 3.0 μm or more and 20.0 μm or less, and even more preferably 5.0 μm or more and 15.0 μm or less.

[0036] Therefore, the function of the binder material becomes readily apparent, and the binder material particles C2 are easily dispersed in the molded body, thereby suppressing uneven distribution of starch and fiber. This further enhances the strength of the molded body. Furthermore, since the average particle size is 30.0 μm or less, the total surface area per unit mass of binder material particles C2 increases. This improves the water absorption of the binder material particles C2, thereby reducing the amount of water required during the manufacturing of the molded body. Therefore, this can be considered a preferred manufacturing method for dry molding. Moreover, the processability of the composite C10 is improved, and its flowability is enhanced when transporting the composite C10 via piping.

[0037] The binding material particles C2 can also include binding materials other than starch. Examples of binding materials other than starch include glycogen, hyaluronic acid, konjac, etherified tamarind gum, etherified locust bean gum, etherified guar gum, and gum arabic as natural gums, etherified carboxymethyl cellulose and hydroxyethyl cellulose as fiber-derived gums, sodium alginate and agar as seaweed, collagen, gelatin, hydrolyzed collagen, and sericin and other compounds derived from natural substances, polyvinyl alcohol, polyacrylic acid, and polyacrylamide.

[0038] In addition to binding materials such as starch, the binding material particles C2 may also contain components that do not have the function of binding fibers together even when water is provided. Examples of such components include color materials such as pigments, dyes, and toners, as well as fiber materials.

[0039] The starch content in the bound material particles C2 is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, relative to the total mass of the bound material particles C2.

[0040] The composite C10 may also contain binding material particles C2 that are not attached to inorganic oxide particles C3, in other words, binding material particles C2 that will not form composite particles C1. However, relative to the total mass of the binding material particles C2 contained in the composite C10, the proportion of binding material particles C2 that form composite particles C1 is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0041] 1.1.2. Inorganic oxide particles

[0042] By positioning the inorganic oxide particles C3 on the surface of the binding material particles C2, agglomeration in the composite particles C1 can be suppressed. The average particle size of the inorganic oxide particles C3 is preferably 1 nm or more and 20 nm or less, more preferably 5 nm or more and 18 nm or less.

[0043] Thus, aggregation is further suppressed in the composite particles C1, and fluidity is improved without excessive surface unevenness. Furthermore, the inorganic oxide particles C3 become easier to adhere to the surface of the binding material particles C2 and are less likely to detach from the surface of the binding material particles C2.

[0044] The composite C10 may also contain inorganic oxide particles C3 that do not adhere to the binding material particles C2; in other words, it may contain inorganic oxide particles C3 that do not form composite particles C1. However, relative to the total mass of the inorganic oxide particles C3 contained in the composite C10, the proportion of inorganic oxide particles C3 that form composite particles C1 is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0045] The parent particles of inorganic oxide particles C3 contain inorganic oxides. Because the parent particles contain inorganic oxides, the heat resistance of inorganic oxide particles C3 can be improved.

[0046] Materials that can serve as the parent material for inorganic oxide particles C3 include, for example, silica, bauxite, titanium dioxide, zirconium oxide, magnetite, ferrite and other metal oxides, as well as glass materials such as soda glass, crystal glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass. Among these materials, silica is preferred because it can improve the adhesion between the parent material and the coating layer derived from the surface treatment agent. Furthermore, silica has a relatively small impact on the color tone of the molded body, making it suitable for manufacturing sheet-like molded bodies.

[0047] The parent particles of inorganic oxide particles C3 may also contain organic matter, or inorganic matter other than inorganic oxides such as metal nitrides, metal sulfides, and metal carbides. The content of inorganic oxides is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 95% by mass or more, relative to the total mass of the parent particles of inorganic oxide particles C3.

[0048] Preferably, the inorganic oxide particles C3 have a coating layer derived from surface treatment on the surface of the parent particles. The coating layer is preferably formed using a surface treatment agent such as a fluorine-containing compound or a silicon-containing compound. This further suppresses agglomeration in the bonding material particles C2 and the composite particles C1. Furthermore, the flowability and handleability of the composite C10 can be improved, thereby increasing productivity in the manufacture of the molded article. Moreover, by efficiently reducing the surface free energy of the inorganic oxide particles C3, the wettability of the composite C10 to the fibers is improved.

[0049] Fluorinated compounds used as surface treatment agents include, for example, perfluoropolyethers and fluorinated modified silicone oils.

[0050] Silicon-containing compounds used as surface treatment agents include, for example, various silicone compounds such as polydimethylsiloxane with trimethylsilyl groups at the ends, polydimethylsiloxane with hydroxyl groups at the ends, polymethylphenylsiloxane, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, methanol-modified silicone oil, polyether-modified silicone oil, and alkyl-modified silicone oil.

[0051] Among the various silicone compounds described above, polydimethylsiloxanes with trimethylsilyl groups at the ends are preferred. In other words, it is preferable that the coating layer of the parent particle of inorganic oxide particle C3 has trimethylsilyl groups on its surface. This further suppresses aggregation in inorganic oxide particle C3, binding material particle C2, and composite particle C1.

[0052] The coating layer of the inorganic oxide particles C3 preferably contains 2.0% by mass or more carbon relative to the total mass of the inorganic oxide particles. This reduces the number of hydroxyl groups present on the surface of the inorganic oxide particles C3, thereby decreasing hydrophilicity. Therefore, for example, it can suppress moisture absorption by the inorganic oxide particles C3 during storage, etc.

[0053] The aforementioned surface treatment agents can be used individually or in combination. When using multiple types of surface treatment agents, multiple types can also be used for a single parent particle. Furthermore, regarding multiple types of surface treatment agents, one type of surface treatment agent can be used for a single parent particle, and the inorganic oxide particles C3 with different surface treatment agents can be mixed together.

[0054] The composite C10 is preferably satisfied in addition to the above conditions, it also satisfies the following conditions.

[0055] The content of the binding material particles C2 in the composite C10 is preferably 90.0% by mass or more and 99.9% by mass or less relative to the total mass of the composite C10, more preferably 95.0% by mass or more and 99.7% by mass or less, and even more preferably 97.0% by mass or more and 99.4% by mass or less. This further improves the strength of the molded article.

[0056] The content of inorganic oxide particles C3 in composite C10 is preferably 0.1% by mass or more and 10.0% by mass or less relative to the total mass of composite C10, more preferably 0.3% by mass or more and 5.0% by mass or less, and even more preferably 0.6% by mass or more and 3.0% by mass or less. This further suppresses the aggregation of composite particles C1.

[0057] 2. Manufacturing method of the molded body

[0058] like Figure 2 As shown, the manufacturing method of the molded body involved in this embodiment includes a raw material supply process, a coarse crushing process, a fiber desiccation process, a screening process, a first sheet forming process, a dividing process, a mixing process, a disassembly process, a second sheet forming process as a stacking process, a humidification process, a sheet forming process as a forming process, and a cutting process.

[0059] In the method for manufacturing the molded article, from the upstream raw material supply process to the downstream cutting process, the sheet-like molded article is manufactured through each process in the above-described order. Furthermore, the method for manufacturing the molded article of the present invention includes an accumulation process, a humidification process, and a forming process, while other processes are not limited to those described above. First, a summary of the second sheet forming process, the humidification process, and the sheet forming process in the method for manufacturing the molded article of this embodiment will be given.

[0060] In the second sheet forming process, a mixture comprising composite C10 and fibers is deposited in air, wherein composite C10 contains a binding material. That is, the method for manufacturing the molded article of the present invention is a manufacturing method related to dry forming.

[0061] The content of complex C10 in the mixture is preferably 1% by mass or more and 50% by mass or less relative to the total mass of the mixture, 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.

[0062] This allows for maintaining a high fiber content in the molded article and improving its strength. Furthermore, it enhances the transportability of the mixture during the manufacturing process.

[0063] For the fibers contained in the mixture, water may be pre-applied, for example, before the humidification process described later. In this case, the water content in the pre-applied fibers is preferably 0.1% by mass or more and 12.0% by mass or less relative to the total mass of the fibers, 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.

[0064] Therefore, the effects of static electricity on the fibers can be suppressed upstream of the second sheet forming process. Specifically, for example, adhesion of fibers to the walls of the forming apparatus caused by static electricity is suppressed. Furthermore, during the preparation of the mixture, uneven distribution of fibers and composite C10 is suppressed and they are mixed together. Additionally, water can be supplied to the fibers from the time they are set as a mixture until the sheet forming process.

[0065] Fibers are the main component of molded articles manufactured through molding processes. Fibers greatly contribute to maintaining the shape of the molded article and have a significant impact on its strength and other properties.

[0066] The fiber is preferably a material containing one or more of the following groups: hydroxyl, carbonyl, and amino groups. This facilitates the formation of hydrogen bonds between the fiber and the starch contained in the C10 composite. Therefore, the bonding strength between the fiber and the starch can be increased, thereby further enhancing the strength of the molded article. Furthermore, the fiber is preferably capable of maintaining its fibrous shape through heating during the sheet forming process.

[0067] Although fibers can also be synthetic fibers containing synthetic resins such as polypropylene, polyester, and polyurethane, from the perspective of environmental protection and resource conservation, fibers derived from natural substances, i.e., derived from biomass, are preferred.

[0068] Among biomass-derived fibers, cellulose fibers are preferred. Cellulose fibers are a relatively abundant natural raw material derived from plants. Therefore, the use of cellulose fibers promotes responses to environmental issues and the conservation of storage resources. Furthermore, cellulose fibers have advantages in terms of raw material supply and cost. Moreover, cellulose fibers theoretically possess exceptionally high strength among various fibers, which also contributes to the increased strength of molded products.

[0069] Although cellulose fibers are primarily formed from cellulose, they can also contain components other than cellulose. Examples of components other than cellulose include hemicellulose and lignin. Furthermore, cellulose fibers can be treated with processes such as bleaching.

[0070] Fibers can also be treated with ultraviolet light, ozone, and plasma. These treatments generate functional groups such as hydroxyl groups on the fiber surface. Therefore, the hydrophilicity of the fiber can be increased, thereby enhancing the affinity between starch and fiber.

[0071] The average length of the fibers 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 even more preferably 0.3 mm or more and 3.0 mm or less. This improves the shape stability of the molded article.

[0072] The average fiber thickness is preferably 0.005 mm or more and 0.500 mm or less, more preferably 0.010 mm or more and 0.050 mm or less. This improves the shape stability of the molded article and, more importantly, enhances the surface smoothness of the molded article.

[0073] The average aspect ratio of the fibers, that is, the ratio of average length to average thickness, is preferably 10 or more and 1000 or less, more preferably 15 or more and 500 or less. This improves the shape stability of the molded article, and also enhances the smoothness of the molded article's surface.

[0074] Water is introduced into the mixture during the humidification process. The water introduced into the mixture is used for starch gelatinization. Through the introduction of water and the heating in the subsequent sheet-forming process, the starch gelatinizes to bind the fibers together.

[0075] Methods for supplying water to a mixture include, for example, exposing the mixture to a high-humidity atmosphere or exposing the mixture to a water-containing mist. In the humidification process, one of these methods can be used alone or in combination. Specifically, various humidifiers, such as vaporization humidifiers and ultrasonic humidifiers, can be used for water supply.

[0076] In the humidification process, the amount of water supplied to the mixture is preferably 12% by mass or more and 40% by mass or less relative to the total mass of the mixture, more preferably 15% by mass or more and 35% by mass or less, and even more preferably 20% by mass or more and 30% by mass or less.

[0077] As mentioned above, starch gelatinization is promoted by controlling the gelatinization temperature of starch by reducing the content of alkali metal salts. Therefore, although the range of water supplied is significantly smaller compared to existing wet papermaking methods, starch gelatinization is easily achieved. Thus, this can be considered a manufacturing method that is more preferred for dry forming.

[0078] Furthermore, the application of water to the mixture can be performed in processes other than the humidification process. Additionally, the water applied to the mixture may contain components other than water, such as preservatives, antifungal materials, and pesticides.

[0079] The sheet forming process includes a heating process and a pressurizing process. In the sheet forming process, a mixture to which water has been added is heated and pressurized to obtain a shaped body. Heating the mixture promotes the gelatinization of the starch in the mixture, thereby binding the fibers in the mixture together. At this time, by pressing the mixture, the shaped body is formed into a desired shape, such as a sheet. Alternatively, the humidification process and the sheet forming process described above can be performed in parallel. Furthermore, the heating process and the pressurizing process can also be performed separately in the sheet forming process.

[0080] In the sheet forming process, the heating temperature for heating the mixture is preferably 60°C or higher and 200°C or lower, more preferably 70°C or higher and 150°C or lower, and even more preferably 80°C or higher and 130°C or lower. This suppresses deterioration and modification caused by excessive heating of the fibers and composite C10 of the mixture. Furthermore, it improves the flowability of composite C10, making it easier for the composite C10 to wet and spread on the fibers. Therefore, the quality of the formed article can be improved. In addition, since starch readily gelatinizes, the heating temperature is also lower, which is also preferable from the viewpoint of energy saving required for heating.

[0081] In the sheet forming process, the pressure applied to the mixture is preferably 0.2 MPa or more and 10.0 MPa or less, more preferably 0.2 MPa or more and 10.0 MPa or less, and even more preferably 0.3 MPa or more and 5.0 MPa or less. This suppresses fiber breakage and splitting in the mixture, thereby further improving the strength of the formed article.

[0082] Next, a specific example of the method for manufacturing the molded article will be described together with the apparatus for manufacturing the molded article. Furthermore, the apparatus for manufacturing the molded article described below is an example and is not intended to be limited thereto.

[0083] like Figure 3 As shown, the sheet manufacturing apparatus 100 for manufacturing sheet-shaped shaped bodies includes a raw material supply unit 11, a coarse crushing unit 12, a fiber debonding unit 13, a screening unit 14, a first sheet forming unit 15, a fine crushing unit 16, a mixing unit 17, a disassembly unit 18, a second sheet forming unit 19, a sheet forming unit 20, a cutting unit 21, and a material preparation unit 22. Furthermore, in Figure 3 In Chinese, the upper side is sometimes called the upper side, the lower side is called the lower side, the left side is called the left side, and the right side is called the right or downstream side.

[0084] The sheet manufacturing apparatus 100 also includes humidification units 231, 232, 233, and 234. Furthermore, the sheet manufacturing apparatus 100 includes a control unit (not shown). The control unit comprehensively controls all structures of the sheet manufacturing apparatus 100.

[0085] The raw material supply process is carried out in the raw material supply section 11. The raw material supply section 11 supplies sheet material M1 to the coarse crushing section 12. The sheet material M1 is, for example, ordinary paper containing fibers such as cellulose fibers.

[0086] A coarse crushing process is performed in the coarse crushing section 12. The coarse crushing section 12 coarsely crushes the sheet material M1 supplied from the raw material supply section 11 in a gas such as air. The coarse crushing section 12 has a pair of coarse crushing blades 121 and a hopper 122.

[0087] While a pair of coarse shredding blades 121 rotate in opposite directions, they coarsely shred the sheet-like material M1 between them. Through the pair of coarse shredding blades 121, the sheet-like material M1 is cut into coarse fragments M2. The shape of the coarse fragments M2 is preferably suitable for the defibering process of the defibering section 13, for example, small pieces with a length of 10 mm or more and 70 mm or less.

[0088] The hopper 122 is positioned below a pair of coarse crushing blades 121. The hopper 122 is generally funnel-shaped, narrowing at the bottom. Thus, the hopper 122 receives and collects the coarse fragments M2 that have been coarsened by the pair of coarse crushing blades 121 and fall downwards.

[0089] Above the hopper 122, a humidifying unit 231 is arranged adjacent to a pair of coarse crushing blades 121 in the left-right direction. The humidifying unit 231 humidifies the coarse fragments M2 inside the hopper 122. The humidifying unit 231 includes a vaporizing humidifier, which, although not shown in the figure, has a filter impregnated with water. By passing air through this filter, humidified air is generated and supplied to the coarse fragments M2. This suppresses the charging of the coarse fragments M2, making it difficult for the coarse fragments M2 to adhere to the hopper 122 or the like.

[0090] The hopper 122 is connected to the defiberization section 13 via the pipe 241, which serves as the conveying path for the coarse fragments M2. Therefore, the coarse fragments M2 collected by the hopper 122 are conveyed to the defiberization section 13 through the pipe 241.

[0091] The defibering process is performed in the defibering section 13. The defibering section 13 defibers the coarse fragments M2 in a gas such as air, in other words, in a dry manner. Through the defibering process in the defibering section 13, the coarse fragments M2 are transformed into a defibered material M3. Here, defibering refers to the process of separating the coarse fragments M2, which are formed by bonding multiple fibers, one fiber at a time. That is, the defibered material M3 is a substance formed by separating the multiple fibers of the coarse fragments M2 individually. The defibered material M3 is cotton-like or ribbon-like in shape. Furthermore, in the defibered material M3, multiple fibers may also intertwine with each other to form clumps, thereby forming a mass.

[0092] A blower 261 and a pipe 242 are arranged between the defiberization section 13 and the screening section 14. The blower 261 is an airflow generating device. The blower 261 generates an airflow by rotating a rotor (not shown) to draw coarse fragments M2 from the hopper 122 to the defiberization section 13 via the pipe 241. In addition, the defiberized material M3 is conveyed to the screening section 14 via the pipe 242 by this airflow.

[0093] A screening process is performed in the screening unit 14. The screening unit 14 screens the defiberized material M3 according to the length of the fibers or the size of the blocks. In the screening unit 14, the defiberized material M3 is screened into a first screening material M4-1 and a second screening material M4-2, which is larger than the first screening material M4-1. The first screening material M4-1 is a size suitable for the material of the sheet S used as the forming body. The second screening material M4-2 may contain, for example, substances that have not been adequately defiberized or substances formed by excessive aggregation of the defiberized fibers.

[0094] The screening section 14 has a roller section 141 and a housing section 142. The housing section 142 houses the roller section 141. The desiccant M3 flows into the interior of the roller section 141.

[0095] The roller section 141 is cylindrical, and the sides of the cylinder are formed by a mesh. The roller section 141 rotates about the central axis of the cylinder. The mesh on the side of the roller section 141 functions as a sieve. As the roller section 141 rotates, the defiber material M3 inside the roller section 141 passes through the mesh as a first screening material M4-1 due to the rotation of the roller section 141, while the defiber material M3 with larger mesh sizes remains inside the roller section 141 as a second screening material M4-2.

[0096] The first screening material M4-1 passes through the mesh on the side of the roller section 141. Furthermore, the first screening material M4-1 falls downwards while being dispersed in the air within the housing section 142. A first sheet forming section 15 is disposed below the roller section 141.

[0097] A humidifying section 232 is connected to the housing portion 142. The humidifying section 232 includes a vaporization-type humidifier similar to that of the humidifying section 231. Humidified air is supplied into the housing portion 142 through the humidifying section 232. As a result, the charging of the first filter material M4-1 is suppressed, making it difficult for the first filter material M4-1 to adhere to the inner wall or other surfaces of the housing portion 142.

[0098] The second screened material M4-2 is conveyed to the pipe 243, which communicates with the interior of the roller section 141. The pipe 243 is connected to the roller section 141 from the inside. Therefore, the second screened material M4-2 is conveyed from the pipe 243 to the pipe 241 and mixed with the coarse fragments M2 in the pipe 241. That is, the second screened material M4-2 is subjected to defibering treatment again in the defibering section 13.

[0099] A first sheet forming process is performed in the first sheet forming section 15. The first sheet forming section 15 forms a first sheet M5 from the first screened material M4-1. The first sheet forming section 15 has a mesh belt 151 as a separating belt, three support rollers 152, and a suction section 153.

[0100] The mesh belt 151 is a seamless belt made of mesh. The mesh opening of the mesh belt 151 is smaller than that of the first screened material M4-1. Therefore, the first screened material M4-1 falling from the roller section 141 will not pass through the mesh of the mesh belt 151 and will accumulate on top of the mesh belt 151.

[0101] The mesh belt 151 is wound around three support rollers 152. When the support rollers 152 are driven to rotate, the mesh belt 151... Figure 3 The screen rotates clockwise, thereby conveying the first screened material M4-1 accumulated on top to the downstream side. The screening process of the screening section 14 and the rotation of the mesh belt 151 are carried out continuously in parallel. Therefore, the first screened material M4-1 accumulated on the mesh belt 151 is stacked into layers, thus becoming the first material sheet M5.

[0102] Here, if dust or the like gets mixed into the first screening material M4-1, it will pass through the mesh of the mesh belt 151 and fall downwards compared to the mesh belt 151, thus being discharged. For example, such dust may be mixed in with the sheet material M1 when the sheet material M1 is supplied from the raw material supply section 11 to the coarse crushing section 12.

[0103] A suction unit 153 is arranged opposite the housing portion 142 in the vertical direction, separated by a mesh belt 151. When viewed from the side, the suction unit 153 is located inside the mesh belt 151 wound around the three support rollers 152. The suction unit 153 draws air from the housing portion 142 above it by passing through the mesh belt 151 facing the housing portion 142.

[0104] The first screened material M4-1 is drawn onto the surface above the mesh belt 151 by the suction of the suction unit 153, thereby promoting the formation of the first material sheet M5 on the mesh belt 151. Furthermore, the aforementioned dust passes through the mesh belt 151 and is sucked in. The suction unit 153 is connected to the recovery unit 27 via the pipe 244. The dust sucked in by the suction unit 153 is recovered by the recovery unit 27.

[0105] A pipe 245 and a blower 262 are also connected to the recovery section 27. The blower 262 exerts the suction force in the suction section 153. That is, the blower 262 causes the suction section 153 to draw air from above via the pipe 245, the recovery section 27, and the pipe 244.

[0106] A humidification unit 235 is disposed downstream of the screening unit 14. The humidification unit 235 includes an ultrasonic humidifier and sprays water in a mist form to humidify the first material sheet M5. Therefore, the moisture content of the first material sheet M5 is regulated, thereby suppressing the charging of the first material sheet M5 and making it difficult for the first material sheet M5 to adhere to the mesh belt 151 due to static electricity. As a result, it becomes easy to peel the first material sheet M5 off the mesh belt 151 at its downstream end.

[0107] A subdivision section 16 is disposed downstream of the humidification section 235. A segmentation process is performed in the subdivision section 16. The subdivision section 16 segments the first sheet M5 peeled off from the mesh belt 151. The subdivision section 16 has a rotating blade 161 supported in a rotatable manner and a housing section 162 for housing the rotating blade 161. The rotating blade 161 contacts the first sheet M5, thereby segmenting the first sheet M5. The first sheet M5 is segmented into subdivided pieces M6. The subdivided pieces M6 fall downward within the housing section 162.

[0108] A humidifying section 233 is connected to the housing portion 162. The humidifying section 233 includes a vaporization-type humidifier similar to that of the humidifying section 231. Humidified air is supplied into the housing portion 162 through the humidifying section 233. As a result, the charging of the subdivided element M6 is suppressed, making it difficult for the subdivided element M6 to adhere to the inner wall of the housing portion 162 or the rotating blade 161, etc.

[0109] A mixing section 17 is disposed downstream of the subdivision section 16. A mixing process is performed in the mixing section 17. The mixing section 17 mixes the subdivision M6 and the composite C10. The mixing section 17 includes a composite supply section 171, a pipe 172, and a blower 173.

[0110] The tube 172 connects the lower part of the housing portion 162 with the housing portion 182 of the disassembly portion 18. The subdivided part M6 and the mixture M7 of the subdivided part M6 and the composite C10 flow in the tube 172.

[0111] A composite supply unit 171 is connected to a pipe 172 between the housing portion 162 and the blower 173. The composite supply unit 171 has a screw feeder 174. When the screw feeder 174 is driven to rotate, the composite C10 is supplied from the composite supply unit 171 into the pipe 172. When the composite C10 is supplied into the pipe 172, the composite C10 and the subdivided particles M6 are mixed to form a mixture M7.

[0112] The composite C10 supplied to the tube 172 may, for example, include a coloring material for coloring the fibers, an aggregation inhibitor for inhibiting the aggregation of the fibers and the composite C10, and a flame retardant for imparting flame retardancy to the fibers.

[0113] Blower 173 is positioned downstream of the location connected to composite supply section 171 within pipe 172. Blower 173 generates an airflow within pipe 172 towards disassembly section 18. This airflow, within pipe 172, simultaneously agitates the fine particles M6 and composite C10 before being conveyed to disassembly section 18. Blower 173 effectively suppresses uneven distribution of fine particles M6 and composite C10 within mixture M7.

[0114] A disassembly section 18 is located downstream of the pipe 172. A disassembly process is performed in the disassembly section 18. The disassembly section 18 carefully disassembles the intertwined fibers contained in the mixture M7. The disassembly section 18 has a roller section 181 and a housing section 182 that houses the roller section 181. The pipe 172 communicates with the interior of the roller section 181, allowing the mixture M7 to flow into the roller section 181.

[0115] The roller section 181 is cylindrical, and the sides of the cylinder are formed by a mesh. The roller section 181 rotates about the central axis of the cylinder. The mesh on the side of the roller section 181 functions as a sieve. As the mixture M7 flowing into the roller section 181 is broken down by the rotation of the roller section 181, fibers smaller than the mesh openings pass through the mesh of the roller section 181.

[0116] The mixture M7, having passed through the mesh of the roller section 181, disperses in the air within the housing section 182 while falling downwards from the roller section 181. A second sheet forming section 19 is disposed below the roller section 181.

[0117] A humidifying section 234 is connected to the housing portion 182. The humidifying section 234 includes a vaporization-type humidifier similar to that of the humidifying section 231. Humidified air is supplied from the humidifying section 234 to the housing portion 182. As a result, the charging of the mixture M7 is suppressed, making it difficult for the mixture M7 to adhere to the inner wall or other surfaces of the housing portion 182.

[0118] A second sheet forming process is performed in the second sheet forming section 19. The second sheet forming section 19 forms a second sheet M8 from the mixture M7. The second sheet forming section 19 has a mesh belt 191 as a separating belt, four support rollers 192, and a suction section 193.

[0119] The mixture M7 falls from the roller section 181 onto the surface above the mesh belt 191. The mesh belt 191 is a seamless belt made of mesh. The mesh openings of the mesh belt 191 are smaller compared to the majority of the mixture M7 falling from the roller section 181. Therefore, the mixture M7 does not pass through the mesh of the mesh belt 191 and accumulates on the surface above the mesh belt 191.

[0120] The mesh belt 191 is wound around four support rollers 192. When the support rollers 192 are driven to rotate, the mesh belt 191... Figure 3 The conveyor belt rotates clockwise, thereby conveying the mixture M7 accumulated at the top to the downstream side. The disassembly process of the disassembly section 18 and the rotation of the conveyor belt 191 are carried out continuously in parallel. Therefore, the mixture M7 accumulated on the conveyor belt 191 is stacked into layers, thus becoming the second sheet M8.

[0121] A suction unit 193 is arranged opposite the housing portion 182 in the vertical direction, separated by a mesh belt 191. When viewed from the side, the suction unit 193 is located inside the mesh belt 191 wound around the four support rollers 192. The suction unit 193 is connected to the blower 263 via a pipe 246.

[0122] Blower 263 exerts suction force in suction section 193. That is, blower 263 causes suction section 193 to draw air from above via pipe 246. As a result, suction section 193 draws air from inside housing section 182 through mesh belt 191 facing housing section 182. Therefore, the formation of the second sheet M8 on mesh belt 191 is promoted.

[0123] A humidifying section 236 is disposed downstream of the area of ​​the housing portion 182 opposite to the mesh belt 191. Like the humidifying section 235, the humidifying section 236 includes an ultrasonic humidifier that sprays water in a mist form to humidify the second sheet M8. This regulates the moisture content of the second sheet M8, thereby increasing the bonding force between the fibers and the composite C10 in the manufactured sheet S. Furthermore, the charging of the second sheet M8 is suppressed, making it difficult for the second sheet M8 to adhere to the mesh belt 191. This makes it easier to peel the second sheet M8 from the mesh belt 191 at its downstream end.

[0124] A sheet forming section 20 is disposed downstream of the second sheet forming section 19. A sheet forming process is performed in the sheet forming section 20. The sheet forming section 20 has a pressure heating section 201. The second sheet M8 peeled off from the mesh belt 191 is conveyed to the sheet forming section 20.

[0125] The pressure heating section 201 has a pair of hot rollers 203. In the sheet forming process, the pair of hot rollers 203 are used to form the sheet S from the second sheet M8.

[0126] The second sheet M8 is heated and pressurized simultaneously by passing it between a pair of heated rollers 203. Each of the heated rollers 203 has a built-in heater (not shown). This heater raises the surface temperature of each heated roller 203.

[0127] Heating and pressurization are applied to the second sheet M8 in parallel via a pair of heated rollers 203. That is, heating and pressurization are performed simultaneously using the pair of heated rollers 203. Specifically, heating to a higher temperature than that applied by the pair of heated rollers 203 is not performed on the second sheet M8 in processes prior to the sheet forming process. Furthermore, applying pressure higher than that applied by the pair of heated rollers 203 is not performed on the second sheet M8 in processes prior to the sheet forming process.

[0128] Thus, the starch in the composite C10 of the second sheet M8 melts, causing the fibers to bond together and forming a sheet S. Since the second sheet M8 is pressurized and heated in parallel by a pair of heated rollers 203, the bonding of the fibers is promoted, thereby increasing the strength of the sheet S. Furthermore, the manufacturing process of the sheet S can be simplified. Moreover, since a pair of heated rollers 203 are responsible for both heating and pressurization, the apparatus is simplified compared to using a separate device for heating and pressurization, making miniaturization easier.

[0129] The surface temperature of each hot roller 203 is preferably 70°C or higher and 140°C or lower. This suppresses fiber deterioration in the second sheet M8. Furthermore, it gelatinizes the starch, thereby further promoting fiber bonding.

[0130] As described above, the pressure applied to the second sheet M8 composed of the mixture M7 by a pair of heated rollers 203 is preferably 0.2 MPa or more and 10.0 MPa or less, more preferably 0.2 MPa or more and 10.0 MPa or less, and even more preferably 0.3 MPa or more and 5.0 MPa or less. This facilitates the wetting and spreading of starch onto the surface of the fibers, thereby further promoting the bonding of the fibers together.

[0131] One of the pair of heated rollers 203 is a driving roller driven by a motor (not shown), and the other is a driven roller. The second sheet M8 passes through the pressurized heating section 201 of the sheet forming section 20 to become a sheet S, and is conveyed to the downstream cutting section 21.

[0132] A cutting process is performed in the cutting section 21. The cutting section 21 cuts the sheet S into the desired shape. The cutting section 21 has a first shear 211 and a second shear 212. In the cutting section 21, the first shear 211 is arranged downstream from the sheet forming section 20 side, followed by the second shear 212.

[0133] The first shear 211 cuts the sheet S in a direction intersecting the direction in which the sheet S is conveyed. The second shear 212 cuts the sheet S in a direction along which the sheet S is conveyed. The first shear 211 and the second shear 212 result in a neat shape for the sheet S. Furthermore, the sheet S is stored in a preparation section 22 located downstream of the cutting section 21. The sheet S is manufactured using the above methods.

[0134] Although the sheet S is exemplified as a molded body in this embodiment, the shape of the molded body realized by the manufacturing method of the molded body of the present invention is not limited to the above description. Besides sheet-like shapes, various other shapes such as block-like, spherical, and three-dimensional shapes can also be listed as molded bodies. Among these shapes, the manufacturing method of the molded body of the present invention and the bonding materials are more preferred for manufacturing sheet-like molded bodies in order to improve the strength of the molded body.

[0135] When the shaped body is a thin sheet S, the density of the thin sheet S is preferably 0.6 g / cm³. 3 Above and 0.9g / cm 3 Therefore, for example, the thin film S is more suitable for recording media used in inkjet recording. In addition to being used in recording media, the thin film S can also be processed for use in liquid absorbers, cushioning materials, and sound-absorbing materials.

[0136] According to this embodiment, the following effects can be obtained.

[0137] In dry forming, the strength of the sheet S manufactured from fibers and composite C10 can be improved. Specifically, by suppressing the content of alkali metal salts contained in starch, the gelatinization temperature of the starch is stabilized and easily managed. Therefore, by controlling the gelatinization temperature, the bonding between fibers in the mixture M7 achieved by starch gelatinization is promoted. As a result, the strength of the sheet S can be improved. That is, in dry forming, a method for manufacturing a molded body that improves the strength of the sheet S and composite C10 as a bonding material can be provided.

[0138] 3. Examples and Comparative Examples

[0139] Hereinafter, embodiments and comparative examples are shown, and the effects of the present invention will be described in more detail. For Embodiments 1 to 14 and Comparative Examples 1 to 3, sheets S as shaped articles were manufactured and evaluated. Hereinafter, Embodiments 1 to 14 may simply be referred to as Embodiments, and Comparative Examples 1 to 3 as Comparative Examples. Furthermore, the present invention is not limited by the following embodiments.

[0140] Regarding the various levels of the embodiments and comparative examples, Tables 1 and 2 show the types and specifications of starch, the types of inorganic oxide particles C3, the conditions of the manufacturing process of the molded articles, and the evaluation results of the strength of the molded articles. The details of the types of starch and inorganic oxide particles C3 in Tables 1 and 2 are described below.

[0141] Types of starch

[0142] ·1…Product name NSP-B1. Japan Starch Chemical Co., Ltd.

[0143] ·2…Product name LUSTERGEN (registered trademark) FK. Japan Starch Chemical Co., Ltd.

[0144] Types of inorganic oxide particles C3

[0145] • A… Fumed silica, product name REOLOSIL (registered trademark) ZD-30ST (hydrophobic grade, surface-treated product. The carbon content of the coating layer derived from the parent particle surface is 2.9% by mass relative to the total mass of the inorganic oxide particles). Tokuyama Corporation.

[0146] • B… Fumed silica, product name REOLOSIL (registered trademark) QS-30 (hydrophilic grade, no surface treatment). Tokuyama Corporation.

[0147] Table 1

[0148]

[0149] Table 2

[0150]

[0151] 3.1. Preparation of Starch

[0152] The preparation, analysis, and measurement of starch were carried out using the following method. First, starches 1 and 2 were subjected to a pulverization process as a pretreatment. Specifically, starches 1 and 2 were pulverized using a reverse-jet pulverizer AFG-R from Hosokawa Micron Corporation's fluidized bed jet pulverizer to form bound material particles C2. In starches 1 or 2 of embodiments other than Examples 11 and 12, the compressed air pressure during pulverization in the above-mentioned apparatus was set to 800 kPa. In starch 1 of Example 11, the compressed air pressure was set to 1200 kPa, and in starch 1 of Example 12, the compressed air pressure was set to 100 kPa.

[0153] In Comparative Example 1, starch 1 was subjected to the same pulverization process as the starch in the examples after a predetermined amount of Fujifilm and Kosei Chemical Co., Ltd. sodium chloride was added as an alkali metal salt prior to the pulverization process described above. In Comparative Example 2, starch 1 was subjected to the same pulverization process as the starch in the examples after a predetermined amount of Fujifilm and Kosei Chemical Co., Ltd. potassium chloride was added as an alkali metal salt prior to the pulverization process described above. In Comparative Example 3, starch 1 was subjected to the same pulverization process as the starch in the examples after a predetermined amount of Fujifilm and Kosei Chemical Co., Ltd. sodium sulfate was added as an alkali metal salt prior to the pulverization process described above.

[0154] 3.1.1. Average particle size of starch

[0155] Regarding the starches of the embodiments and comparative examples that underwent pulverization treatment, the average particle size of the starch particles was measured using the method described above, and the results are shown in Tables 1 and 2.

[0156] 3.1.2. Combining qualitative and quantitative analysis of alkali metal salts in the materials.

[0157] Using a Rigaku Corporation TG-DTA (Thermogravimetry-Differential Thermal Analysis) apparatus TG8121, each starch was thermally decomposed at 850°C for 30 minutes under an inert gas atmosphere such as nitrogen or helium. Subsequently, qualitative and quantitative analyses were performed on the thermal decomposition residue using energy dispersive X-ray spectroscopy (EDS). Based on the mass of starch before TG-DTA measurement, the mass of the thermal decomposition residue, and the results of EDS analysis, the types and contents of alkali metal salts contained in the bound material were determined.

[0158] Based on the results of the above analysis, each starch in the examples contains sodium chloride, an alkali metal salt. In the starch of Comparative Example 1, the amount of sodium chloride originally contained in starch 1 and the amount of sodium chloride added before the pulverization process were detected.

[0159] In the starch of Comparative Example 2, sodium chloride originally present in starch 1 and potassium chloride added before the pulverization process were detected. The content of alkali metal salts in the starch of Comparative Example 2 was the sum of the amount of sodium chloride originally present in starch 1 and the amount of potassium chloride added before the pulverization process.

[0160] In the starch of Comparative Example 3, sodium chloride originally present in starch 1 and sodium sulfate added before the pulverization process were detected. The alkali metal salt content in the starch of Comparative Example 3 was the sum of the amount of sodium chloride originally present in starch 1 and the amount of sodium sulfate added before the pulverization process. The alkali metal salt content in each starch is shown in Tables 1 and 2.

[0161] 3.1.3. Measurement of starch gelatinization temperature

[0162] For the starches used in the examples and comparative examples, the gelatinization temperature was measured using a Thermoplus EVO DSC8231 differential scanning calorimeter from Rigaku Corporation, Japan. Specifically, a solution containing 1 part starch and 2 parts deionized water by mass was sealed in a pressure-resistant aluminum dish as a test sample. Next, the test sample was placed in the apparatus, and differential calorimetry was performed at a heating rate of 2°C per minute. The endothermic peak value (peak-to-valley value) in the obtained DSC curves was read as the gelatinization temperature, and is shown in Tables 1 and 2. However, in Comparative Examples 1, 2, and 3, the gelatinization temperature could not be determined because the endothermic peak value of the DSC curves showed branching.

[0163] 3.2. Fabrication of the composite

[0164] Complexes were prepared using starches from examples other than Example 13 and comparative examples. Specifically, pulverized starch and inorganic oxide particles C3 were loaded into a Henschel FM mixer from Coke & Engineering, Japan, and mixed at a frequency of 60 Hz for 10 minutes. Afterward, coarse particles larger than 30 μm were removed by passing the mixture through a sieve with a mesh opening of 30 μm, thereby obtaining a complex. In Example 13, the above operation was performed using only pulverized starch without the addition of inorganic oxide particles C3, and the same treatment as for complex preparation was carried out. That is, Example 13 represents a level where no complex was formed.

[0165] 3.3. Manufacturing of the molded body

[0166] Molded articles were manufactured for both the embodiment and the comparative example. Specifically, a device was used, which was a modified Seiko Epson PaperLab A-8000 dry office paper machine that could humidify the sheet before post-forming processing. In the sheet feeder of the above device, used paper printed with business documents on FUJIXEROX GR-70W recycled copy paper by an inkjet printer was loaded as the sheet material M1, and the device was set to a basis weight of 90 g / m². 2 .

[0167] Next, the composite of the embodiment and the comparative example, and the processed product of Example 13 were respectively loaded into the box of the above-mentioned device. The above-mentioned box was sequentially loaded into the above-mentioned device, and recycled sheets as molded articles of the embodiment and the comparative example were manufactured. In addition, the conditions of the humidification process and the molding process during manufacturing were set to the values ​​shown in Table 1 and Table 2.

[0168] The molded body of Example 1 is made by using starch 1 and inorganic oxide particles A, with the amount of water supplied in the humidification process set to 20% by mass, the heating temperature in the molding process set to 90°C, and the pressure applied in the molding process set to 2.0 MPa.

[0169] Example 2 is an example in which starch 2 is used instead of starch 1, as in Example 1.

[0170] Examples 3, 4, 5, and 6 represent changes to the heating temperature of the forming process compared to Example 1.

[0171] Examples 7 and 8 represent changes to the pressure applied during the forming process compared to Example 1.

[0172] Examples 9 and 10 are different from Example 1 in that the amount of water supplied in the humidification process is changed.

[0173] Examples 11 and 12 represent adjustments to the compressed air pressure during the pulverization process and changes to the average particle size, relative to Example 1.

[0174] Example 13 represents the level of starch not forming a complex, as opposed to Example 1, without the use of inorganic oxide particles.

[0175] Example 14 is an example in which inorganic oxide particles B are used instead of inorganic oxide particles A, as opposed to Example 1.

[0176] In Comparative Examples 1, 2, and 3, the content of alkali metal salts contained in the starch was increased compared to Example 1. In Comparative Examples 1, 2, and 3, the content of alkali metal salts was set to exceed 2.0% by mass relative to the total mass of the starch.

[0177] 3.4. Evaluation of the strength of the molded body

[0178] Tensile strength was measured as an indicator of the strength of the molded body. Specifically, an AUTOGRAPHAGS-1N tensile testing machine from Shimadzu Corporation was used. Immediately after the molded body was manufactured, a 100mm x 20mm rectangle was cut from it to create a test piece. The test piece was placed in the aforementioned apparatus with its long side aligned with the tensile direction. Then, the breaking strength along the long side of the test piece was measured at a tensile speed of 20mm per second. The tensile strength was calculated by comparing the measured breaking strength with the density of the molded body, and evaluated according to the following criteria.

[0179] 5: Specific tensile strength is above 25 Nm / g.

[0180] 4: The specific tensile strength is above 20 Nm / g and less than 25 Nm / g.

[0181] 3: The specific tensile strength is above 15 Nm / g and less than 20 Nm / g.

[0182] 2: The specific tensile strength is above 10 Nm / g and less than 15 Nm / g.

[0183] 1: Specific tensile strength is less than 10 Nm / g.

[0184] As shown in Tables 1 and 2, the evaluation results of the specific tensile strength of all embodiments are within the allowable range of 2 or higher. In particular, in Embodiments 1, 2, 4, and 5, the evaluation result is equivalent to 5 (excellent), and in Embodiments 3 and 6, the evaluation result is equivalent to 4 (good). Thus, the improved strength of the molded articles is demonstrated in these embodiments.

[0185] In contrast, as shown in Table 2, the evaluation results for the specific tensile strength of all comparative examples were equivalent to a poor score of 1. This indicates that it was difficult to improve the strength of the molded articles in the comparative examples.

[0186] Symbol Explanation

[0187] 203…a pair of hot rollers; C2…bonding material particles; C3…inorganic oxide particles; C10…composite as a bonding material; M7…mixture; S…sheet as a shaped body.

Claims

1. A method for manufacturing a shaped article, comprising: The stacking process involves stacking a mixture containing fibers and binding materials in air, the binding materials comprising starch that has been acid-treated with hydrochloric acid or sulfuric acid and an alkali metal salt derived from the acid treatment and a neutralization treatment, the neutralization treatment being carried out using sodium hydroxide or potassium hydroxide after the average molecular weight of the starch has been adjusted by hydrochloric acid or sulfuric acid. In the humidification process, water is supplied to the mixture; The forming process involves heating and pressurizing the mixture to which the water has been added to obtain a shaped body. The content of the alkali metal salt in the binding material is less than 2.0% by mass relative to the total mass of the starch. In the humidification process, the amount of water supplied to the mixture is 12% by mass or more and 40% by mass or less relative to the total mass of the mixture. The average particle size of the bonding material is greater than 1.0 μm and less than 30.0 μm. The particles of the bonding material contain inorganic oxide particles in a manner that makes them integral.

2. The method for manufacturing the molded article as described in claim 1, wherein, The gelatinization temperature of the starch is above 30°C and below 60°C.

3. The method for manufacturing the molded article as described in claim 1 or claim 2, wherein, In the forming process, a pair of hot rollers are used.

4. The method for manufacturing a molded article as described in claim 1, wherein, In the forming process, the pressure applied to the mixture is 0.2 MPa or more and 10.0 MPa or less.

5. The method for manufacturing a molded article as described in claim 1, wherein, The inorganic oxide particles have a coating layer on their surface. The coating layer contains more than 2.0% by mass of carbon relative to the total mass of the inorganic oxide particles.

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