Binder and method for producing a molded body

Abstract

To provide a binder for use as binding material in production of a molding by binding fibers or the like, from which a molding having sufficient strength can be produced.SOLUTION: A binder C10 comprises a binding material particle C2 including a binding material for binding fibers to each other with addition of water, and an inorganic particle C3. The binder C10 further comprises a composite particle C1 in which the binding material particle C2 and the inorganic particle C3 are integrated into one. The inorganic particle C3 has a specific surface area of 150 m2 / g or more and 280 m2 / g or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a binder and a method for manufacturing a molded body.

Background Art

[0002] As a method for manufacturing a molded body such as a cushioning material by recycling waste paper without using a large amount of water as in the papermaking method, a method for manufacturing a molded body has been proposed in which waste paper is defibrated into a cotton-like material, atomized moisture is added, and further a powdery or granular adhesive material is added to manufacture a molded body (see, for example, Patent Document 1). Such a method for manufacturing a molded body has an advantage that a molded body can be manufactured using only a small amount of water as compared with the papermaking method, so that energy and time consumed for dehydration, drying, etc. can be saved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above method for manufacturing a molded body, even if a powdery adhesive material is simply mixed with the fibers, it is difficult to uniformly distribute the adhesive material in the molded body, and as a result, it may be difficult to sufficiently ensure the strength of the obtained molded body. In particular, when manufacturing a sheet-like molded body such as recycled paper as the molded body, if there is an area where the amount of the adhesive material is small, the molded body may break starting from that portion, and the strength of the sheet may decrease.

Means for Solving the Problems

[0005] The binder contains binder material particles containing a binder material that binds fibers together when moisture is imparted, and inorganic particles. The binder contains composite particles in which the binder material particles and the inorganic particles are integrated. The specific surface area of the inorganic particles is 150 m 2 / g or more and 280 m 2 / g or less.

[0006] The method for manufacturing a molded body includes a deposition step of depositing a mixture containing fibers and the above binder, a humidification step of humidifying the deposited mixture, and a molding step of obtaining a molded body by heating and pressurizing the humidified mixture.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] 1. Binder As shown in FIG. 1, the binder C10 is a binder C10 containing binder material particles C2 containing a binder material that binds fibers together when moisture is imparted, and inorganic particles C3. The binder C10 contains composite particles C1 in which the binder material particles C2 and the inorganic particles C3 are integrated. The specific surface area of the inorganic particles C3 is 150 m 2 / g or more and 280 m 2 / g or less. The binder C10 is used by being mixed with fibers as described later, and is used to bind the fibers together to manufacture a molded body.

[0009] In the present invention, a state in which at least a part of the inorganic particles C3 adheres to the surface of the binder particles C2 or at least a part of the inorganic particles C3 is contained inside the binder particles C2 to form the composite particles C1 is referred to as "the composite particles C1 in which the binder particles C2 and the inorganic particles C3 are integrated". That is, it does not exclude the case where the binder C10 contains the binder particles C2 that do not form the composite particles C1 and the inorganic particles C3.

[0010] In the illustrated configuration, in the composite particles C1 contained in the binder C10, the inorganic particles C3 adhere to the surface of the binder particles C2.

[0011] Thereby, a repulsive force acts between the inorganic particles C3, and aggregation between the binder particles C2 is less likely to occur. The arrangement of the inorganic particles C3 can be confirmed by, for example, various electron microscopes.

[0012] 1.1. Composite particles The composite particles C1 contained in the binder C10 may be those in which a single inorganic particle C3 adheres to the surface of a single binder particle C2. However, the binder C10 preferably contains, as the composite particles C1, particles in which a plurality of inorganic particles C3 adhere to the surface of a single binder particle C2.

[0013] Thereby, a repulsive force acts between the inorganic particles C3, and aggregation between the binder particles C2 becomes even less likely to occur.

[0014] The average particle diameter 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. Thereby, it becomes easier to uniformly distribute the composite particles C1 in the molded body.

[0015] In this specification, the average particle diameter refers to the median diameter (D50 value at a cumulative frequency of 50%) unless otherwise specified. The average particle diameter can be obtained, for example, by measurement using Microtrac UPA (manufactured by Nikkiso Co., Ltd.).

[0016] 1.1.1. Binder particles The binder particles C2 contain a binder that exhibits a binding force for binding fibers together when moisture is imparted thereto.

[0017] Examples of the binder constituting the binder particles C2 include natural product-derived components such as starch, dextrin, glycogen, amylose, hyaluronic acid, kudzu starch, konjac, arrowroot starch, etherified starch, esterified starch, natural gum pastes (etherified tamarind gum, etherified locust bean gum, etherified guar gum, acacia arabica-based gum), fiber-derived pastes (etherified carboxymethyl cellulose, hydroxyethyl cellulose), seaweeds (sodium alginate, agar), animal-derived proteins (collagen, gelatin, hydrolyzed collagen, sericin), etc., and polyvinyl alcohol, polyacrylic acid, polyacrylamide, etc. One or more selected from these can be used in combination, but natural product-derived components are preferred, and starch is more preferred.

[0018] Starch is a polymer material in which a plurality of α-glucose molecules are polymerized by glucoside bonds. Starch contains at least one of amylose and amylopectin.

[0019] By using natural product-derived components as the binder, the use of petroleum-derived materials is suppressed, the CO2 emission amount is reduced, and an excellent effect according to the present invention, that is, when used as a binder when manufacturing a molded body by binding fibers or the like, an effect that a molded body having sufficient strength can be manufactured is obtained. In addition, such materials are also excellent in biodegradability.

[0020] In particular, starch is a material that exhibits suitable binding force when gelatinization progresses upon heating after water is added, that is, a binding material that suitably exhibits a binding force for binding fibers together when water is added. Further, starch exhibits a binding force through non-covalent bonds such as hydrogen bonds with fibers composed of materials having functional groups such as hydroxyl groups, particularly fibers such as cellulose fibers, has excellent binding force with fibers, and exhibits excellent coating property with respect to fibers. Therefore, the strength and the like of the molded body produced using the binder C10 can be made more excellent.

[0021] The binding material preferably contains starch having a weight average molecular weight of 50,000 or more and 400,000 or less.

[0022] Thereby, the water absorption efficiency of the binder C10 can be made more excellent, and a molded body having sufficient strength can be produced. More specifically, even when the amount of water added is small, gelatinization of starch by heating proceeds suitably, the productivity of the molded body using the binder C10 can be made excellent, and the strength of the produced molded body can be made excellent. Further, starch having a weight average molecular weight within the above range is less likely to undergo unintended modification due to water addition.

[0023] Starch controlled so that the weight average molecular weight becomes a value within a predetermined range can be suitably obtained as follows. For example, after suspending natural starch in water, sulfuric acid, hydrochloric acid, or sodium hypochlorite is allowed to act under conditions where the starch does not gelatinize, whereby starch controlled so that the weight average molecular weight becomes a value within a predetermined range can be obtained. Further, for example, natural starch is directly added, or a volatile acid such as hydrochloric acid in a very small amount is diluted with water and added, mixed well, aged, dried at a low temperature, and then heated to 120 to 180°C, whereby starch controlled so that the weight average molecular weight becomes a value within a predetermined range can be obtained. Further, for example, by subjecting a paste liquid obtained by heating natural starch together with water to a treatment of hydrolysis with an acid or an enzyme, starch controlled so that the weight average molecular weight becomes a value within a predetermined range can be suitably obtained.

[0024] As described above, the weight average molecular weight of the starch as the binder material is preferably 50,000 or more and 400,000 or less, more preferably 70,000 or more and 300,000 or less, and even more preferably 80,000 or more and 200,000 or less. Thereby, the water absorption efficiency of the binder material can be made even better, and a molded body having sufficient strength can be manufactured.

[0025] Incidentally, the weight average molecular weight of the starch can be determined from the measurement by gel permeation chromatography. The weight average molecular weight shown in the examples described later is also a value determined from the measurement by gel permeation chromatography.

[0026] In addition to the binder material, the binder material particles C2 may contain components other than the binder material, that is, components that do not exhibit a binding force to bind fibers even when moisture is added. Examples of such components include fiber materials, pigments, dyes, color materials such as toners, and the like.

[0027] The content rate of the binder material in the binder 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.

[0028] The average particle diameter of the binder 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 μm or less.

[0029] Thus, when manufacturing a molded body using the binder C10, in the step of mixing the fibers and the binder C10, the fibers and the binder C10 can be mixed more uniformly. Also, when water is added to the mixture of the fibers and the binder C10, the absorption of water proceeds more smoothly, and the strength and reliability of the finally obtained molded body can be made more excellent. In particular, when the particle size of the binder material particles C2 is relatively small in this way, the ratio of the surface area to the mass of the binder material particles C2 increases, and the water absorption efficiency by the binder material becomes more excellent. As a result, even when the amount of water added is small, a molded body with sufficient strength can be manufactured. Also, in the binder C10, when the binder material particles C2 with such a small average particle size were not coexisted with the inorganic particles C3, aggregation of the binder material particles C2 often occurred. However, in the present invention, by using the composite particles C1 in which the binder material particles C2 and the inorganic particles C3 are integrated, aggregation of the binder material particles C2 can be effectively prevented. That is, even when the average particle size of the binder material particles C2 is a value within the above range, by making the composite particles C1 in which the binder material particles C2 and the inorganic particles C3 are integrated, aggregation between the binder material particles C2 can be suppressed.

[0030] The binder C10 may contain binder material particles C2 to which the inorganic particles C3 are not attached, in other words, binder material particles C2 that do not constitute the composite particles C1. However, the ratio of the binder material particles C2 that constitute the composite particles C1 to the total binder material particles C2 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. Thereby, aggregation between the binder material particles C2 can be more effectively suppressed, and a molded body excellent in strength can be manufactured.

[0031] 1.1.2. Inorganic Particles The composite particles C1 contain inorganic particles C3. The specific surface area of the inorganic particles C3 is 150 m 2 / g or more and 280 m 2 / g or less, and 180 m 2 / g or more and 230 m 2It is preferably below / g.

[0032] The specific surface area of the inorganic particles C3 is 150 m 2 / g or more and 280 m 2 / g or less, whereby the angle of repose of the composite particles C1 can be reduced. Therefore, when the composite particles C1 are mixed with the fibers, the fluidity of the composite particles C1 is enhanced. Thus, when the binder C10 is used as a binding material in manufacturing a molded body by binding fibers or the like, the composite particles C1 can be more uniformly mixed with the fibers. As a result, a molded body in which the binder material particles C2 are more uniformly distributed can be manufactured, and the molded body has sufficient strength because the binder material particles C2 are uniformly distributed. Furthermore, since the binder C10 of the present invention is excellent in dispersibility, it is possible to effectively suppress the binder C10 from aggregating inadvertently during storage of the binder C10 or during conveyance of the binder C10 in the manufacturing process of the molded body.

[0033] The average particle diameter 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 still more preferably 5.0 nm or more and 10.0 nm or less.

[0034] Thereby, it is suitably suppressed that excessive irregularities occur on the surface of the composite particles C1 to which the inorganic particles C3 adhere to the surface of the binder material particles C2. Therefore, when the composite particles C1 are mixed with the fibers, the fluidity of the binder C10 can be made more excellent, and the composite particles C1 can be more uniformly mixed with the fibers. In addition, the inorganic particles C3 can be more suitably adhered to the surface of the binder material particles C2, and it is possible to prevent the inorganic particles C3 from inadvertently falling off from the surface of the binder material particles C2 or from inadvertently burying inside the binder material particles C2. Further, when the average particle diameter of the inorganic particles C3 is 1.0 nm or more and 20.0 nm or less, a repulsive force acts between the inorganic particles C3, and the effect of the binder C10, which suppresses the aggregation of the binder material particles C2 and improves the dispersibility of the composite particles C1 by including the composite particles C1 in which the binder material particles C2 and the inorganic particles C3 are integrated, is more remarkably exhibited.

[0035] The binder C10 may contain inorganic particles C3 that are not attached to the binder material particles C2, in other words, inorganic particles C3 that do not constitute the composite particles C1. However, the proportion of the inorganic particles C3 that constitute the composite particles C1 in the 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. Thereby, the effect that the binder C10, which suppresses the aggregation of the binder material particles C2 and improves the dispersibility of the composite particles C1, is more significantly exhibited by including the composite particles C1 in which the binder material particles C2 and the inorganic particles C3 are integrated.

[0036] The inorganic particles C3 may mainly be composed of an inorganic material. Further, the inorganic particles C3 may have a substantially uniform composition at each part, or may have parts with different compositions.

[0037] More specifically, for example, the inorganic particles C3 may be those in which particles composed of an inorganic material are surface-treated with at least one kind of surface treatment agent. In other words, the inorganic particles C3 may have particles composed of an inorganic material and a coating layer by the surface treatment agent that coats the particles.

[0038] Thereby, for example, the unintentional aggregation of the binder material particles C2 can be more effectively prevented, the wet spreading on the fiber surface of the binder material in the molding process can be made better, and the strength of the finally obtained molded body can be made more excellent.

[0039] Examples of the material constituting the inorganic particles C3 include various metal materials, various metal compounds, various glass materials, various carbon materials, and the like.

[0040] Examples of the metal material include simple metals such as Fe, Al, Cu, Ag, Ni, and alloys containing at least one of these.

[0041] Examples of the metal compound include metal oxides, metal nitrides, metal carbides, metal sulfides, etc. More specifically, silica, alumina, zirconia, titanium oxide, magnetite, ferrite, etc. are included.

[0042] Examples of the glass material include soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, alkali-free glass, etc.

[0043] Examples of the carbon material include diamond, carbon fiber, carbon black, carbon nanotube, carbon nanofiber, fullerene, etc.

[0044] Among them, silica is preferable as the constituent material of the inorganic particles C3. In other words, the inorganic particles C3 are preferably composed of a material containing silica.

[0045] Thereby, the dispersibility of the composite particles C1 is further improved. As a result, it is possible to effectively suppress the involuntary aggregation of the binder C10 during storage of the binder C10 or during transportation of the binder C10 in the manufacturing process of the molded body.

[0046] The inorganic particles C3 only need to be mainly composed of an inorganic material, and may contain an organic material in addition to the inorganic material.

[0047] However, the content rate of the inorganic material in the inorganic particles C3 is preferably 90% by mass or more, more preferably 92% by mass or more, and further preferably 95% by mass or more.

[0048] 1.1.3. Other configurations The binder C10 includes the composite particles C1 described above, and may further include other configurations. For example, the binder C10 may include the binder material particles C2 to which the inorganic particles C3 are not attached together with the composite particles C1 described above, or may include the inorganic particles C3 not attached to the binder material particles C2.

[0049] However, the content rate of the composite particles C1 in the binder C10 is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. Thereby, the above-described effects are more significantly exhibited.

[0050] 1.1.4. Other Conditions The binder C10 preferably satisfies the following conditions.

[0051] For example, the content rate of the binder material particles C2 in the binder C10 is preferably 90.0% by mass or more and 99.9% by mass or less, 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. Thereby, the above-described effects are more significantly exhibited.

[0052] The coating rate of the inorganic particles C3 with respect to the surface area of the binder material particles C2 in the binder C10 is preferably 80% or more and 400% or less, and more preferably 100% or more and 250% or less. Here, the coating rate of the inorganic particles C3 with respect to the surface area of the binder material particles C2 is a value defined by the following formula.

[0053]

Equation

[0054] Thereby, the dispersibility of the composite particles C1 is improved. That is, by setting the coating rate of the inorganic particles C3 to 80% or more and 400% or less, aggregation of the composite particles C1 to form coarse particles is suppressed. As a result, unintentional aggregation of the binder C10 is effectively suppressed during storage of the binder C10 or during conveyance of the binder C10 in the manufacturing process of the molded body.

[0055] 2. Method for Producing Binder The binder C10 of the present embodiment can be manufactured by mixing binder particles C2 and inorganic particles C3 by an appropriate method. That is, the binder particles C2 adjusted to a desired molecular weight and average particle size and the inorganic particles C3 are prepared and mixed and stirred using a stirrer such as a super mixer, a Henschel mixer, or a turbulizer. By stirring the binder particles C2 and the inorganic particles C3 under a certain shearing force, frictional heat is generated on the particle surface, and the integration of the binder particles C2 and the inorganic particles C3 proceeds. Then, sieving is performed with a sieve having an aperture of 20 μm to 100 μm to obtain the binder C10.

[0056] 3. Method for manufacturing a molded body The method for manufacturing a molded body includes a deposition step of depositing a mixture containing fibers and the above-mentioned binder C10, a humidifying step of humidifying the deposited mixture, and a molding step of obtaining a molded body by heating and pressurizing the humidified mixture. And the binder C10 is a binder C10 containing binder particles C2 containing a binding material that binds the fibers by imparting moisture and inorganic particles C3. The binder C10 contains composite particles C1 in which the binder particles C2 and the inorganic particles C3 are integrated, and the specific surface area of the inorganic particles C3 is 150 m 2 / g or more and 280 m 2 / g or less.

[0057] In the method for manufacturing a molded body of the present embodiment, the angle of repose of the composite particles C1 can be reduced, so that the composite particles C1 can be uniformly mixed with the fibers. Therefore, a molded body in which the binding material is more uniformly distributed can be obtained, and a molded body having sufficient strength can be manufactured.

[0058] 3.1. Deposition step In the deposition step, a mixture containing fibers and the binder C10 is deposited.

[0059] The mixing ratio of the fiber and the binder C10 in this step is not particularly limited, but the content of the binder C10 in the mixture obtained in this step 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] Thereby, while making the fiber content in the finally obtained molded body sufficiently high, the strength of the molded body can be made more excellent. In addition, the conveyance of the binder C10 in the manufacturing process of the molded body can be performed more smoothly.

[0061] In this step, the fiber mixed with the binder C10 may be, for example, one that has been previously humidified before the humidification step described later, that is, the step of performing humidification treatment on the mixture. Further, the fiber may be humidified during the deposition of the mixture obtained by this mixing from the mixing with the binder C10.

[0062] In the case as described above, the moisture content in the fiber supplied to this step 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] Thereby, for example, it is possible to effectively prevent the fiber from being adversely affected by static electricity before this step, for example, the fiber adhering to the wall surface of the manufacturing apparatus of the molded body or the like due to static electricity, and it is also possible to mix the fiber and the binder C10 more uniformly.

[0064] 3.1.1. Fiber The fiber is the main component of the molded body manufactured using the method for manufacturing the molded body, and greatly contributes to maintaining the shape of the molded body and also greatly affects the properties such as the strength of the molded body.

[0065] The fiber may be made of any material, but it is preferably one that can maintain its fibrous state even when heated in the forming process.

[0066] In particular, the fiber is preferably composed of a substance containing at least one chemical structure among a hydroxyl group, a carbonyl group, and an amino group.

[0067] Thereby, for example, when starch is used as the binding material, it becomes easier to form hydrogen bonds between the fiber and the binding material, and the binding strength between the fiber and the binding material can be made more excellent, and the strength of the entire molded body, for example, the tensile strength of the sheet-shaped molded body, etc. can be made more excellent.

[0068] The fiber may be a synthetic fiber composed of a synthetic resin such as polypropylene, polyester, polyurethane, etc., but is preferably a natural fiber, that is, a biomass-derived fiber, and more preferably a cellulose fiber.

[0069] Thereby, it is possible to more suitably respond to environmental problems and conservation of buried resources, etc. In particular, when the fiber is a cellulose fiber, the following effects can also be obtained.

[0070] That is, cellulose fiber is a natural material rich in plant origin. By using cellulose fiber as the fiber, it is possible to more suitably respond to environmental problems and conservation of buried resources, etc., and it is also preferable from the viewpoints of stable supply of the molded body and cost reduction, etc. Also, cellulose fiber has a particularly high theoretical strength among various fibers, and is advantageous from the viewpoint of further improving the strength of the molded body.

[0071] Cellulose fiber is usually mainly composed of cellulose, but may contain components other than cellulose. Examples of such components include hemicellulose, lignin, etc.

[0072] In addition, as the cellulose fiber, those subjected to treatments such as bleaching may be used.

[0073] In addition, the fiber may be one subjected to treatments such as ultraviolet irradiation treatment, ozone treatment, and plasma treatment. By this, the hydrophilicity of the fiber can be enhanced, and the affinity with the binding material can be enhanced. More specifically, by these treatments, functional groups such as hydroxyl groups can be introduced onto the surface of the fiber, and hydrogen bonds can be formed more efficiently between the fiber and the binding material.

[0074] The average length of the fiber 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 even more preferably 0.3 mm or more and 3.0 mm or less.

[0075] Thereby, the shape stability, strength, etc. of the produced molded body can be made more excellent.

[0076] The average thickness of the fiber 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.

[0077] Thereby, the shape stability, strength, etc. of the produced molded body can be made more excellent. In addition, the occurrence of unintended irregularities on the surface of the molded body can be more effectively prevented.

[0078] The average aspect ratio of the fiber, that is, the average length with respect 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.

[0079] Thereby, the shape stability, strength, etc. of the produced molded body can be made more excellent. In addition, the occurrence of unintended irregularities on the surface of the produced molded body can be more effectively prevented.

[0080] 3.1.2. Binding Material As the binder C10 to be mixed with the fibers, those described in "1. Binder Material" are used.

[0081] 3.2. Humidifying Step In the humidifying step, the mixture deposited in the deposition step, that is, the mixture containing fibers and the binder C10, is humidified.

[0082] Thereby, in the molding step described later, the bonding strength between the fibers and the binder material and the bonding strength between the fibers via the binder material can be made excellent, and the strength of the finally obtained molded body can be made sufficiently excellent. Further, the molding in the molding step can be suitably performed under relatively mild conditions.

[0083] The method of humidifying the mixture is not particularly limited, but it is preferably performed in a non-contact manner with respect to the mixture. For example, methods such as placing the mixture in a high-humidity atmosphere, passing the mixture through a high-humidity space, spraying a mist of a liquid containing water onto the mixture, and passing the mixture through a space in which a mist of a liquid containing water is floating can be mentioned, and one or more methods selected from these can be combined and performed. More specifically, the humidification of the mixture can be performed using various humidifiers such as vaporization type and ultrasonic type. The humidification of the mixture may be performed at a plurality of stages, for example, in the process of manufacturing the molded body. Note that the liquid containing water may contain, for example, a preservative, a fungicide, an insecticide, or the like.

[0084] The amount of moisture imparted to the mixture in the humidifying step is not particularly limited, but it is preferably to impart 1 to 50 parts by mass of moisture, more preferably 5 to 40 parts by mass of moisture, and even more preferably 10 to 30 parts by mass of moisture with respect to 100 parts by mass of the mixture subjected to the humidifying step.

[0085] Thereby, a molded body having sufficient strength can be manufactured with significantly less moisture compared to the conventional papermaking method, and the effects of the present invention can be more significantly exhibited.

[0086] 3.3. Forming Process In the forming process, the mixture humidified in the humidifying process is pressurized and heated. Thereby, a formed body is obtained. Note that the humidifying process and the forming process may be carried out simultaneously.

[0087] The pressure applied to the mixture in the forming process is not particularly limited, but is preferably 0.1 MPa or more and 100.0 MPa or less, and more preferably 0.3 MPa or more and 80.0 MPa or less.

[0088] Thereby, the binder C10 can be more suitably spread and wetted on the surface of the fiber. As a result, the strength of the produced formed body can be made more excellent.

[0089] The heating temperature in the forming process is not particularly limited, but is preferably 50°C or more and 200°C or less, more preferably 60°C or more and 150°C or less, and even more preferably 70°C or more and 120°C or less.

[0090] Thereby, while effectively preventing unwanted deterioration, denaturation, etc. of the components of the fiber and the binder C10, the binder C10 can be more suitably spread and wetted on the surface of the fiber. As a result, the strength and reliability of the produced formed body can be made more excellent. Also, it is preferable from the viewpoint of energy saving. In particular, when the binder material particles C2 are composed of a material containing starch as the binder, the gelatinization of the water-absorbed starch can be suitably advanced, and the components of the formed body can be effectively prevented from deteriorating unintentionally.

[0091] The forming process can be carried out using, for example, a hot press, a hot roller, etc. Thereby, while effectively preventing unwanted deterioration, denaturation, etc. of the components of the fiber and the binder C10, the binder C10 can be more suitably spread and wetted on the surface of the fiber. As a result, the strength and reliability of the produced formed body can be made more excellent.

[0092] The method for manufacturing the molded body described above can be preferably implemented using, for example, the manufacturing apparatus for a molded body described below.

[0093] 4. Manufacturing Apparatus for Molded Body Next, the manufacturing apparatus for the molded body will be described.

[0094] FIG. 2 is a schematic explanatory view showing the configuration of the manufacturing apparatus, which is suitable for implementing the method for manufacturing the molded body. In the following, for convenience of explanation, the upper side in FIG. 2 may be referred to as "upper" or "above", the lower side as "lower" or "below", the left side as "left" or "upstream side", and the right side as "right" or "downstream side".

[0095] In the following description, as an example of the manufacturing apparatus for the molded body, an example of a sheet manufacturing apparatus 100 for manufacturing a sheet S as the molded body will be given and described.

[0096] As shown in FIG. 2, the sheet manufacturing apparatus 100, which is a manufacturing apparatus for the molded body, includes a raw material supply unit 11, a crushing unit 12, a defibrating unit 13, a sorting unit 14, a first web forming unit 15, a subdividing 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. Further, the sheet manufacturing apparatus 100 includes a humidifying unit 231, a humidifying unit 232, a humidifying unit 233, and a humidifying unit 234.

[0097] The operations of each part included in the sheet manufacturing apparatus 100 are controlled by a control unit (not shown).

[0098] The method for manufacturing the sheet S as the molded body includes a raw material supply step, a crushing step, a defibrating step, a sorting step, a first web forming step, a dividing step, a mixing step, a loosening step, a second web forming step, a humidifying step, a sheet forming step, and a cutting step. And the sheet manufacturing apparatus 100 can execute these steps in order.

[0099] Hereinafter, the configuration of each part included in the sheet manufacturing apparatus 100 will be described.

[0100] The raw material supply unit 11 is a part that performs a raw material supply process of supplying the sheet-like material M1 to the crushing unit 12. As this sheet-like material M1, it is a sheet-like material containing fibers such as cellulose fibers.

[0101] The crushing unit 12 is a part that performs a crushing process of crushing the sheet-like material M1 supplied from the raw material supply unit 11 in the air such as in the air. The crushing unit 12 has a pair of crushing blades 121 and a hopper 122.

[0102] The pair of crushing blades 121 can crush, that is, cut the sheet-like material M1 between them by rotating in opposite directions to obtain crushed pieces M2. The shape and size of the crushed pieces M2 are preferably suitable for the defibrillation process in the defibrillation unit 13. For example, it is preferably a small piece with a side length of 100 mm or less, and more preferably a small piece with a side length of 10 mm or more and 70 mm or less.

[0103] The hopper 122 is disposed below the pair of crushing blades 121 and has, for example, a funnel shape. Thereby, the hopper 122 can receive the crushed pieces M2 that have been crushed by the crushing blades 121 and have fallen.

[0104] Also, above the hopper 122, a humidifying unit 231 is disposed adjacent to the pair of crushing blades 121. The humidifying unit 231 humidifies the crushed pieces M2 in the hopper 122. This humidifying unit 231 has a filter (not shown) containing moisture and is composed of a vaporizing humidifier that supplies humidified air with increased humidity to the crushed pieces M2 by passing air through the filter. By supplying the humidified air to the crushed pieces M2, it is possible to control the adhesion of the crushed pieces M2 to the hopper 122 or the like due to static electricity.

[0105] The hopper 122 is connected to the defibrillation unit 13 via a pipe 241 that is a flow path. The crushed pieces M2 collected in the hopper 122 pass through the pipe 241 and are conveyed to the defibrillation unit 13.

[0106] The fiberizing section 13 is a part that performs a fiberizing process of fiberizing the crushed pieces M2 in the air such as in the atmosphere, that is, in a dry manner. By the fiberizing process in this fiberizing section 13, fiberized material M3 can be generated from the crushed pieces M2. Here, "fiberize" means to unwind and separate the crushed pieces M2 formed by binding a plurality of fibers into individual fibers one by one. And what is thus unwound becomes the fiberized material M3. The shape of the fiberized material M3 is linear or strip-shaped. Also, the fiberized materials M3 may exist in a state where they are entangled and form a lump, that is, a so-called "clump".

[0107] In the present embodiment, for example, the fiberizing section 13 is composed of an impeller mill having a rotor that rotates at high speed and a liner located on the outer periphery of the rotor. The crushed pieces M2 flowing into the fiberizing section 13 are sandwiched between the rotor and the liner and fiberized.

[0108] Also, the fiberizing section 13 can generate an air flow, that is, an air current, from the crushing section 12 toward the sorting section 14 due to the rotation of the rotor. Thereby, the crushed pieces M2 can be sucked from the pipe 241 into the fiberizing section 13. Also, after the fiberizing process, the fiberized material M3 can be sent out to the sorting section 14 via the pipe 242.

[0109] A blower 261 is installed in the middle of the pipe 242. The blower 261 is an air current generating device that generates an air current toward the sorting section 14. Thereby, the sending out of the fiberized material M3 to the sorting section 14 is promoted.

[0110] The sorting section 14 is a part that performs a sorting process of sorting the fiberized material M3 according to the length of the fibers. In the sorting section 14, the fiberized material M3 is sorted into a first sorted material M4-1 and a second sorted material M4-2 that is larger than the first sorted material M4-1. The first sorted material M4-1 has a size suitable for the subsequent production of the sheet S. The second sorted material M4-2 includes, for example, those with insufficient fiberization or those in which the fiberized fibers are excessively aggregated.

[0111] The sorting unit 14 includes a drum unit 141 and a housing unit 142 that houses the drum unit 141.

[0112] The drum unit 141 is composed of a cylindrical net body and is a sieve that rotates around its central axis. The defibrated material M3 flows into this drum unit 141. Then, as the drum unit 141 rotates, the defibrated material M3 smaller than the mesh opening of the net is sorted as the first sorted material M4-1, and the defibrated material M3 larger than or equal to the mesh opening of the net is sorted as the second sorted material M4-2.

[0113] The first sorted material M4-1 falls from the drum unit 141.

[0114] The second sorted material M4-2 is sent out to a pipe 243, which is a flow path connected to the drum unit 141. The opposite side of the pipe 243 from the drum unit 141 is connected to the pipe 241. The second sorted material M4-2 that has passed through the pipe 243 merges with the crushed pieces M2 in the pipe 241 and flows into the defibrating unit 13 together with the crushed pieces M2. As a result, the second sorted material M4-2 is returned to the defibrating unit 13 and is defibrated together with the crushed pieces M2.

[0115] Also, the first sorted material M4-1 from the drum unit 141 falls while being dispersed in the air and heads toward a first web forming unit 15, which is a separation unit located below the drum unit 141. The first web forming unit 15 is a part that performs a first web forming process of forming a first web M5 from the first sorted material M4-1. The first web forming unit includes a mesh belt 151 that is a separation belt, three tension rollers 152, and a suction unit 153.

[0116] The mesh belt 151 is an endless belt on which the first sorted material M4-1 accumulates. This mesh belt 151 is looped around the three tension rollers 152. Then, due to the rotational drive of the tension rollers 152, the first sorted material M4-1 on the mesh belt 151 is conveyed to the downstream side.

[0117] The first sorted object M4-1 is larger than the mesh opening of the mesh belt 151. As a result, the passage of the first sorted object M4-1 through the mesh belt 151 is restricted, and thus it can accumulate on the mesh belt 151. Also, since the first sorted object M4-1 accumulates on the mesh belt 151 and is conveyed downstream together with the mesh belt 151, it is formed as a layered first web M5.

[0118] In addition, for example, dust and dirt may be mixed in the first sorted object M4-1. Dust and dirt may be mixed in together with the sheet-like material M1 when the sheet-like material M1 is supplied from the raw material supply unit 11 to the crushing unit 12, for example. This dust and dirt is smaller than the mesh opening of the mesh belt 151. As a result, the dust and dirt pass through the mesh belt 151 and further fall downward.

[0119] The suction unit 153 can suck air from below the mesh belt 151. As a result, the dust and dirt that have passed through the mesh belt 151 can be sucked together with the air.

[0120] The suction unit 153 is connected to the collection unit 27 via a pipe 244 which is a flow path. The dust and dirt sucked by the suction unit 153 are collected by the collection unit 27.

[0121] A pipe 245 which is a flow path is further connected to the collection unit 27. Also, a blower 262 is installed in the middle of the pipe 245. By the operation of this blower 262, a suction force can be generated in the suction unit 153. As a result, the formation of the first web M5 on the mesh belt 151 is promoted. This first web M^5 has had the dust and dirt removed. Also, the dust and dirt reach the collection unit 27 by passing through the pipe 244 due to the operation of the blower 262.

[0122] The housing part 142 is connected to the humidifying part 232. The humidifying part 232 is constituted by a vaporizing type humidifier similar to the humidifying part 231. Thereby, humidified air is supplied into the housing part 142. By this humidified air, the first sorted material M4-1 can be humidified, and thus it is also possible to suppress the first sorted material M4-1 from adhering to the inner wall of the housing part 142 by electrostatic force.

[0123] A humidifying part 235 is arranged on the downstream side of the sorting part 14. The humidifying part 235 is constituted by an ultrasonic humidifier that sprays water. Thereby, moisture can be supplied to the first web M5, and thus the moisture content of the first web M5 is adjusted. By this moisture adjustment, it is possible to suppress the adsorption of the first web M5 to the mesh belt 151 by electrostatic force. Thereby, the first web M5 can be easily peeled off from the mesh belt 151 at the position where the mesh belt 151 is folded back by the tensioning roller 152.

[0124] A subdividing part 16 is arranged on the downstream side of the humidifying part 235. The subdividing part 16 is a part that performs a subdividing process of dividing the first web M5 peeled off from the mesh belt 151. The subdividing part 16 has a rotatably supported propeller 161 and a housing part 162 that houses the propeller 161. Then, by the first web M5 being caught by the rotating propeller 161, the first web M5 can be divided. The divided first web M5 becomes the subdivided body M6. Further, the subdivided body M6 descends in the housing part 162.

[0125] The housing part 162 is connected to the humidifying part 233. The humidifying part 233 is constituted by a vaporizing type humidifier similar to the humidifying part 231. Thereby, humidified air is supplied into the housing part 162. By this humidified air, it is also possible to suppress the subdivided body M6 from adhering to the propeller 161 or the inner wall of the housing part 162 by electrostatic force.

[0126] On the downstream side of the subdivision part 16, a mixing part 17 is arranged. The mixing part 17 is a part that performs a mixing process of mixing the fine body M6 and the binder C10 described above. This mixing part 17 has a binder supply part 171, a pipe 172 which is a flow path, and a blower 173.

[0127] The pipe 172 connects the housing part 162 of the subdivision part 16 and the housing part 182 of the loosening part 18, and is a flow path through which the mixture M7 of the fine body M6 and the binder C10 passes.

[0128] In the middle of the pipe 172, the binder supply part 171 is connected. The binder supply part 171 has a screw feeder 174. By rotationally driving 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 fine body M6 to become the mixture M7.

[0129] Note that, from the binder supply part 171, together with the binder C10, for example, a coloring agent for coloring fibers, an aggregation inhibitor for suppressing the aggregation of fibers and the binder C10, a flame retardant for making fibers and the like difficult to burn, etc. may be included.

[0130] Also, in the middle of the pipe 172, a blower 173 is installed on the downstream side of the binder supply part 171. The blower 173 can generate an air flow toward the loosening part 18. By this air flow, in the pipe 172, the fine body M6 and the binder C10 can be stirred. Thereby, the mixture M7 can flow into the loosening part 18 in a state where the fine body M6 and the binder C10 are uniformly dispersed. Also, the fine body M6 in the mixture M7 is loosened in the process of passing through the pipe 172 and becomes finer fibrous.

[0131] The loosening part 18 is a part that performs a loosening process of loosening the fibers intertwined with each other in the mixture M7. The loosening part 18 has a drum part 181 and a housing part 182 that houses the drum part 181.

[0132] The drum part 181 is composed of a cylindrical net body and is a sieve that rotates around its central axis. The mixture M7 flows into this drum part 181. Then, as the drum part 181 rotates, fibers and the like in the mixture M7 that are smaller than the mesh opening can pass through the drum part 181. At this time, the mixture M7 will be loosened.

[0133] The housing part 182 is connected to the humidifying part 234. The humidifying part 234 is composed of a vaporizing type humidifier similar to the humidifying part 231. Thereby, humidified air is supplied into the housing part 182. With this humidified air, the inside of the housing part 182 can be humidified, and thus it is also possible to prevent the mixture M7 from adhering to the inner wall of the housing part 182 by electrostatic force.

[0134] The mixture M7 loosened by the drum part 181 falls while being dispersed in the air and heads toward the second web forming part 19 located below the drum part 181. The second web forming part 19 is a part that performs a second web forming process of forming the second web M8 from the mixture M7. The second web forming process in this embodiment is a deposition process of depositing the mixture M7 containing fibers and the binder C10. The second web forming part 19 includes a mesh belt 191 that is a separation belt, a stretching roller 192, and a suction part 193.

[0135] The mesh belt 191 is an endless belt on which the mixture M7 is deposited. This mesh belt 191 is wound around four stretching rollers 192. Then, by the rotational drive of the stretching roller 192, the mixture M7 on the mesh belt 191 is conveyed to the downstream side.

[0136] Also, most of the mixture M7 on the mesh belt 191 is larger than the mesh opening of the mesh belt 191. As a result, the mixture M7 is suppressed from passing through the mesh belt 191, and thus can be deposited on the mesh belt 191. Further, the mixture M7 is deposited on the mesh belt 191 and conveyed downstream together with the mesh belt 191, so that it is formed as a layered second web M8.

[0137] The suction part 193 can suck air from below the mesh belt 191. Thereby, the mixture M7 can be sucked onto the mesh belt 191, and thus the deposition of the mixture M7 on the mesh belt 191 is promoted.

[0138] A pipe 246 which is a flow path is connected to the suction part 193. Further, a blower 263 is installed in the middle of this pipe 246. By the operation of this blower 263, a suction force can be generated in the suction part 193.

[0139] A humidifying part 236 is arranged on the downstream side of the loosening part 18. The humidifying part 236 is a part that performs the humidifying process described above. The humidifying part 236 is composed of an ultrasonic humidifier similar to the humidifying part 235. Thereby, moisture can be supplied to the second web M8, and thus the moisture content of the second web M8 is adjusted. By this moisture adjustment, the bonding force between the fibers and the binder in the finally obtained sheet S as a molded body can be made suitable.

[0140] In particular, for the binder C10 of the present embodiment, since the specific surface area of the inorganic particles C3 contained in the composite particles C1 is 150 m 2 / g or more and 280 m 2 / g or less, by imparting moisture, the binder C10 can be sufficiently charged. For this reason, the adhesion force of the binder C10 to the second web M8 increases, and the interfiber bonding force inside the sheet S increases, so that it becomes possible to manufacture a sheet S having sufficient strength.

[0141] In addition, by humidifying, it is possible to suppress the adsorption of the second web M8 to the mesh belt 191 due to electrostatic force. As a result, the second web M8 can be easily peeled off from the mesh belt 191 at the position where the mesh belt 191 is folded back by the tensioning roller 192.

[0142] A sheet forming unit 20 is disposed downstream of the second web forming unit 19. The sheet forming unit 20 is a part that performs a sheet forming process, which is a forming process for forming the sheet S from the second web M8. This sheet forming unit 20 has a pressing unit 201 and a heating unit 202.

[0143] The pressing unit 201 has a pair of calendar rollers 203, and the second web M8 can be pressed between them. As a result, the density of the second web M8 is increased. Then, this second web M8 is conveyed toward the heating unit 202. Note that one of the pair of calendar rollers 203 is a driving main roller driven by the operation of a motor (not shown), and the other is a driven roller.

[0144] The heating unit 202 has a pair of heating rollers 204, and can heat and press the second web M8 between them. By this heating and pressing, in the second web M8, the binder C10 melts, and the fibers are bonded to each other through the melted binder C10. As a result, the sheet S as a molded body is formed. Then, this sheet S is conveyed toward the cutting unit 21. Note that one of the pair of heating rollers 204 is a driving main roller driven by the operation of a motor (not shown), and the other is a driven roller.

[0145] A cutting unit 21 is disposed downstream of the sheet forming unit 20. The cutting unit 21 is a part that performs a cutting process for cutting the sheet S. This cutting unit 21 has a first cutter 211 and a second cutter 212.

[0146] The first cutter 211 cuts the sheet S in a direction intersecting with the conveyance direction of the sheet S.

[0147] The second cutter 212 cuts the sheet S in a direction parallel to the conveyance direction of the sheet S on the downstream side of the first cutter 211.

[0148] By cutting with such first cutter 211 and second cutter 212, the sheet S as a molded body of a desired size is obtained. Then, this sheet S is further conveyed to the downstream side and accumulated in the stock unit 22.

[0149] (Example) Next, an example of the present invention will be described.

[0150] 5. Preparation of Binder 5.1. Preparation of Raw Starches 1 to 3 After suspending starch with a weight average molecular weight of 1.3 million (manufactured by Nippon Starch Chemical Co., Ltd., G-800) in water, sulfuric acid was allowed to act under conditions where the starch did not gelatinize, and it was thoroughly mixed and stirred for 12 hours. After drying at 50°C for 24 hours to make the moisture content 10 mass% or less, a paste-like starch was obtained by heating at 120 to 180°C. Thereafter, the paste-like starch was washed with water, freeze-dried, and then coarsely pulverized to obtain raw starch 1 with a weight average molecular weight of 100,000. In addition, except for changing the treatment conditions (concentration of sulfuric acid, stirring time) for starch with a weight average molecular weight of 1.3 million (manufactured by Nippon Starch Chemical Co., Ltd., G-800), it was treated in the same manner as when manufacturing raw starch 1 to obtain raw starch 2 (weight average molecular weight 30,000) and raw starch 3 (weight average molecular weight 500,000).

[0151] 5.2. Preparation of Starch Particles 1 to 3 Raw starch 1 was pulverized using a fluidized bed opposed jet mill (Counter Jet Mill AFG-R, manufactured by Hosokawa Micron Corporation) at a processing pressure of 4 bar to obtain starch particles 1 with an average particle size of 10 μm. In addition, the same treatment as that performed on raw starch 1 was performed on raw starches 2 and 3 to obtain starch particles 2 and 3, respectively. Furthermore, except for changing the processing pressure during pulverization for raw starch 1, it was treated in the same manner as when manufacturing starch particles 1 to obtain starch particles 4 with an average particle size of 4 μm (processing pressure 6 bar) and starch particles 5 with an average particle size of 20 μm (processing pressure 2 bar).

[0152] 5.3. Preparation of Composite Particles (Adjustment Example 1) 1 part by mass of starch particles as binder particles C2 and 1 part by mass of fumed silica (manufactured by Tokuyama Corporation, DM-30S) as inorganic particles C3 were filled into a Henschel mixer (FM mixer FM 20C / I manufactured by Nippon Coke Industry Co., Ltd.) and mixed for 10 minutes at a frequency of 60 Hz. Thereafter, sieving was performed with a sieve having an opening of 30 μm to prepare a binder C10 of Adjustment Example 1 containing composite particles C1 in which the starch particles 1 as binder particles C2 and the fumed silica as inorganic particles C3 were integrated.

[0153] (Adjustment Examples 2 to 13) Binders C10 containing composite particles C1 of Adjustment Examples 2 to 13 were prepared in the same manner as in Adjustment Example 1, except that the types of binder particles C2 and inorganic particles C3 and the blending ratio of binder particles C2 and inorganic particles C3 were changed as shown in Table 1. · DM-30S (Tokuyama Corporation, Rheoseal (registered trademark), product number: DM-30S, fumed silica) · HM-20L (Tokuyama Corporation, Rheoseal, product number: HM-20L, fumed silica) · HM-30S (Tokuyama Corporation, Rheoseal, product number: HM-30S, fumed silica) · ZD-30ST (Tokuyama Corporation, Rheoseal, product number: ZD-30ST, fumed silica) · DM-30 (Tokuyama Corporation, Rheoseal, product number: DM-30, fumed silica) · Aerogel RX-200 (Nippon Aerogel Co., Ltd., Aerosil (registered trademark), product number: RX-200, fumed silica) · Aerogel 300 (Nippon Aerogel Co., Ltd., Aerosil (registered trademark), product number: 300, fumed silica)

[0154]

Table 1

[0155] 6. Manufacturing of the Sheet as a Formed Body (Example 1) In this example, using the binder C10 of the above adjustment example 1, the sheet S as a formed body was manufactured.

[0156] A modified machine obtained by modifying a sheet manufacturing apparatus 100 (PaperLab (registered trademark) A - 8000 manufactured by Seiko Epson Corporation) so that the sheet after forming and before pressing can be humidified was prepared. As the fiber source, a commercially available copy paper (GR70 - W manufactured by Fuji Xerox Co., Ltd.) printed with business documents by an inkjet printer was used as the sheet - like material M1.

[0157] Next, the above sheet - like material M1 was supplied to the raw material supply unit 11 of the sheet manufacturing apparatus 100, and the binder C10 manufactured by preparing the binder was supplied to the binder supply unit 171, and the operation of the sheet manufacturing apparatus was carried out. The processes of a crushing process, a defibering process, a sorting process, a first web forming process, a cutting process, and a mixing process, a loosening process, a second web forming process which is a deposition process, a humidifying process, a sheet forming process which is a forming process, and a cutting process were performed to manufacture an A4 - sized sheet S as a formed body. The basis weight of the obtained sheet was 90 g / m 2 It was.

[0158] At this time, the sheet S as the finally obtained formed body was adjusted so that it contained 10 parts by mass of the binder C10 with respect to 90 parts by mass of the fiber as the raw material. Also, when performing heat - pressing in the heating unit 202, the heating temperature was 80°C, the pressure was 70 MPa, and the heat - pressing time was 2 seconds.

[0159] (Examples 2 - 11, Comparative Examples 1 - 2) An A4 - sized sheet S as a formed body was manufactured in the same manner as in Example 1 except that the binders shown in Table 2 were used as the binder C10.

[0160] 7. Evaluation 7.1. Strength of the Formed Body From the sheets as the molded articles produced in the above-described respective examples and respective comparative examples, strips of 100 mm × 20 mm were cut out, and the breaking strength was measured in the longitudinal direction of the strips. For the measurement of the breaking strength, an Elmendorf tear strength tester manufactured by Kumagai Riki was used, and the evaluation was made according to the following criteria from the calculated specific tear strength.

[0161] A: The specific tear strength is 4 mN·m 2 ·g or more. B: The specific tear strength is 3 mN·m 2 ·g or more and less than 4 mN·m 2 ·g. C: The specific tear strength is 2 mN·m 2 ·g or more and less than 3 mN·m 2 ·g. D: The specific tear strength is 1 mN·m 2 ·g or more and less than 2 mN·m 2 ·g. E: The specific tear strength is less than 1 mN·m 2 ·g. The results are shown in Table 2.

[0162]

Table 2

[0163] As is clear from Table 2, in Examples 1 to 11 in which the molded articles were produced using the binder C10 according to the present invention, the results of the specific tear strength test were evaluated as D or higher, and excellent results were obtained. On the other hand, in Comparative Examples 1 and 2 in which the binder C10 in which the specific surface area of the inorganic particles C3 was not 150 m 2 / g or more and 280 m 2 / g or less was used, the results of the specific tear strength test were E, and satisfactory results were not obtained.

Explanation of Signs

[0164] C10... binder, C1... composite particles, C2... binder material particles, C3... inorganic particles.

Claims

**Claim 1**: A binder comprising binder material particles containing starch having a weight average molecular weight of 70,000 or more and 400,000 or less and an average particle diameter of 1.0 μm or more and 30.0 μm or less, and inorganic particles, wherein the binder contains composite particles in which the binder material particles and the inorganic particles are integrated, and the specific surface area of the inorganic particles is 150 m2 / g or more and 280 m2 / g or less. **Claim 2** The average particle diameter of the inorganic particles is 1.0 nm or more and 20.0 nm or less. The binder according to claim 1 wherein the binder contains composite particles in which the binder material particles and the inorganic particles are integrated, **Claim 3** In the binder, the coverage rate of the inorganic particles with respect to the surface area of the binder material particles is 8 0% or more and 400% or less. The binder according to any one of claims 1 to 2. **Claim 4** The inorganic particles contain silica. The binder according to any one of claims 1 to 3. **Claim 5** A deposition step of depositing a mixture containing fibers and the binder according to any one of claims 1 to 4, a humidifying step of humidifying the deposited mixture, and a molding step of obtaining a molded body by heating and pressurizing the humidified mixture. A method for manufacturing a molded body comprising: ​

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