Patent Description:
The present disclosure relates to a method for producing a shaped article and to a binder.

In the related art, methods are known in which a sheet-shaped article containing fibers and a macromolecular polysaccharide, such as starch, as a binder for the fibers is produced. For example, <CIT> discloses a starch-based paper-strengthening agent whose main constituent is a starch having a relatively small average degree of polymerization.

The starch-based paper-strengthening agent described in <CIT>, however, has a disadvantage: with this agent, it is difficult to improve the strength of a shaped article in dry shaping as well, or in shaping with a small amount of water. This is because, with a small amount of water, fiber fibrils cannot contribute to interfiber bonding, and paper strength enhancers based on a low-molecular-weight starch like that described in <CIT> fail to compensate for the associated lack of interfiber bonding strength. Obtaining a sufficiently strong shaped article with a small amount of water as in the method according to an aspect of the present disclosure for producing a shaped article, therefore, requires using a starch-based paper strength enhancer having an appropriate molecular weight. Obtaining such a starch-based paper strength enhancer requires properly controlling the molecular weight of the starch, and an effective way of doing that is to treat the starch, for example by hydrolysis with an acid or other substances. Molecular-weight control by acid treatment, however, has had a disadvantage as described below.

More precisely, acid treatment of starch can involve neutralizing the acid by adding a material like a hydroxide of an alkali metal. Any residual fraction of the alkali metal salt produced via the neutralization in the starch often causes the gelatinization temperature to fluctuate, and this has made gelatinization temperature control a difficult task. Since the gelatinization temperature of starch is relevant to the strength of a shaped article made therewith, the gelatinization temperature variability has been an obstacle to improving the strength of shaped articles. Overall, there is a need for a method, for producing a shaped article, that improves the strength of the shaped article compared with known methods.

According to an aspect of the present disclosure, a method for producing a shaped article as set out in the appended set of claims.

The embodiments described below provide examples of a binder for dry shaping, a method for producing a sheet-shaped article using this binder, etc., and describe them with reference to drawings. For the sake of convenience, the elements in the drawings are not drawn to scale. The term "dry shaping" herein refers to a shaping process in which a relatively small amount of water is used compared with wet shaping, such as wet sheet-making. The amount of water supplied will be described later herein.

As illustrated in <FIG>, a complex C10 according to this embodiment includes composite particles C1 formed by binding material particles C2, which are particles of a binding material containing starch, and inorganic oxide particles C3 integrated therewith. The complex C10 is an example of a binder according to an aspect of the present disclosure for dry shaping. The complex C10 will act as a binder for fibers in the production of a shaped article containing the fibers.

In this context, inorganic oxide particles C3 being integrated with binding material particles C2 refers to a situation in which at least a subset of the inorganic oxide particles C3 are on the surface of or inside the binding material particles C2. Besides the composite particles C1, the complex C10 may include binding material particles C2 and inorganic oxide particles C3 as separate particles not forming composite particles C1.

In particular, composite particles C1 having inorganic oxide particles C3 on the surface of the binding material particle C2 undergo a repulsive force that acts between the inorganic oxide particles C3.

By virtue of these, the binding material particles C2 do not easily aggregate together. The unevenness in the distribution of the binding material particles C2 in the shaped article will be limited, improving the strength of the shaped article. The state of the inorganic oxide particles C3 on the binding material particles C2 can be observed using, for example, a scanning electron microscope.

The composite particles C1 have one or more inorganic oxide particles C3 on the surface of each one of the binding material particles C2. Preferably, multiple inorganic oxide particles C3 are adhering to the surface of each one of the binding material particles C2. This enhances the preventive effect on the aggregation of the binding material particles C2.

Preferably, the average particle diameter of the composite particles C1 is <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, even more preferably <NUM> or more and <NUM> or less. This further enhances the above effect.

An average particle diameter herein refers to a diameter at a <NUM>% volume in a particle size distribution by volume. The average particle diameter is measured by the dynamic light scattering and laser diffraction methods set forth in JIS Z8825. Specifically, commercially available dynamic light scattering-based particle size analyzers, such as Nikkiso's Microtrac UPA, can be employed. The average particle diameter of the starch is measured using such an analyzer after the starch is dispersed in water or any other solvent.

Preferably, the composite particles C1 content of the complex C10 is <NUM>% by mass or more, more preferably <NUM>% by mass or more, even more preferably <NUM>% by mass or more of the total mass of the complex C10. This reduces unevenness in the distribution of the composite particles C1.

The binding material particles C2 will experience the gelatinization of the starch in the binding material therein when heated after being supplied with water. By gelatinizing, the starch will join fibers together in the mixture described below, a material for the shaped article.

The starch will form noncovalent bonds, such as hydrogen bonds, with the fibers, cellulose fibers in particular, which have hydroxyl and other functional groups. The starch, therefore, will cover the fibers well, improving the strength of the shaped article.

Starch is a polymeric compound formed by multiple α-glucose molecules polymerized by glycosidic bonds. Starch contains at least one of amylose or amylopectin.

The starch can be of any origin, but examples of origins include cereals, such as corn, wheat, and rice; beans, such as peas, broad beans, green gram, and adzuki beans (Vigna angularis); tubers, such as potatoes, sweet potatoes, and tapioca; wild grasses, such as katakuri (Erythronium japonicum), bracken, and kudzu vine (Pueraria montana var. lobata); and palm trees, such as the sago palm. Being of natural origin, starches are effective reducers of carbon dioxide emissions compared with petroleum derivatives and are highly biodegradable at the same time.

The starch may be a modified or altered starch. Examples of modified starches include acetylated distarch adipate, acetylated starch, oxidized starch, starch sodium octenyl succinate, hydroxypropyl starch, hydroxypropyl distarch phosphate, monostarch phosphate, phosphated distarch phosphate, urea phosphate starch, sodium starch glycolate, and high-amylose corn starch.

Examples of altered starches include pregelatinized starch, dextrin, lauryl polyglucose, cationic starches, thermoplastic starches, and starch carbamate. Dextrin is preferably one obtained by modifying or altering starch.

Preferably, the gelatinization temperature of the starch is <NUM> or above and <NUM> or below, more preferably <NUM> or above and <NUM> or below, even more preferably <NUM> or above and <NUM> or below. This ensures the starch will easily gelatinize with a relatively small amount of water even when the heating temperature is relatively low. The starch in that case, therefore, is suitable for producing a shaped article by dry shaping and helps further improve the strength of the shaped article in dry shaping. How to measure the gelatinization temperature of the starch will be described later.

The gelatinization temperature of starch correlates with the chain length, or the average molecular weight, of the starch. When the gelatinization temperature of the starch exceeds <NUM>, therefore, it is preferred to adjust the gelatinization temperature by cutting the polymer chains into lower-molecular-weight segments. The cutting of polymer chains of starch is done by, for example, acid treatment, enzymatic treatment, treatment with an oxidant, or physical treatment. Acid treatment is particularly preferred for its simplicity and ease of implementation. In other words, it is preferred that the starch be an acid-treated starch, hydrolyzed by acid treatment and having an adjusted average molecular weight.

Preferably, the average molecular weight of the starch is, for example, <NUM> or more and <NUM> or less as a weight-average molecular weight. This improves the water absorption of the binding material particles C2, thereby helping reduce the amount of water supplied in the production of the shaped article. The weight-average molecular weight of starch can be determined by GPC (gel permeation chromatography).

A starch treated with an acid can contain a salt, such as an alkali metal salt. In that case, the binding material contains starch and an alkali metal salt. More precisely, acid treatment uses an acid, such as hydrochloric acid or sulfuric acid. After the adjustment of the average molecular weight with the acid, the acid is neutralized with an aqueous solution, for example of sodium hydroxide or potassium hydroxide. During this, the acid for acid treatment and the base for neutralization combine to produce an alkali metal salt, such as sodium chloride, potassium chloride, or sodium sulfate.

The alkali metal salt produced through the acid treatment is eliminated through washing subsequent to the neutralization. In the related art, however, it has leaved so much salt that the gelatinization temperature of the starch will fluctuate. More precisely, the gelatinization temperature of starch is measured by differential scanning calorimetry (DSC). When a sample of a starch relatively rich in an alkali metal salt is analyzed by DSC, the resulting DSC curve, which is an indicator for the gelatinization temperature, tends to be distorted or split. This has made it difficult to pinpoint the exact gelatinization temperature, thereby making gelatinization temperature control a difficult task. During the process of producing a shaped article, furthermore, the alkali metal salt has destabilized gelatinization behavior of binding material particles C2, causing reduced strength of the shaped article.

To address this, the alkali metal salt content of the binding material is reduced to <NUM>% by mass or less of the total mass of the starch, for example through additional washing. Preferably, this percentage is <NUM>% by mass or less, more preferably <NUM>% by mass or less, of the total mass of the starch. This makes the DSC endothermic peak as an indicator of the gelatinization temperature of the starch stable and clear, thereby allowing the manufacturer to control the gelatinization temperature. The reduction of the alkali metal salt content of the starch can be achieved by known washing methods, such as filtration after washing with water and ultrafiltration.

The average particle diameter of the binding material particles C2 is <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, even more preferably <NUM> or more and <NUM> or less.

This makes more certain that the binding material particles C2 will perform their function as a binding material, and at the same time reduces unevenness in the distribution of the starch and the fibers by making the particles C2 more dispersible in the shaped article. The strength of the shaped article, therefore, will be further improved. Since the average particle diameter is <NUM> or less, furthermore, the total surface area per unit mass of the binding material particles C2 is increased. This enhances the water absorption of the binding material particles C2. The amount of water supplied in the production the shaped article will be reduced, and this helps make the production method suitable for dry shaping. The complex C10, furthermore, becomes easier to handle, and flowability is also improved, for example when the complex C10 is transported through piping.

The binding material particles C2 may contain binding materials other than starch. Examples of binding materials other than starch include glycogen, hyaluronic acid, and konjac; tamarind gum ethers, locust bean gum ethers, guar gum ethers, and acacia gum arabic, which are natural gum adhesives; carboxymethylcellulose ethers and hydroxyethylcellulose, which are fiber-derived adhesives; sodium alginate and agar, which are seaweeds; collagen, gelatin, and hydrolyzed collagen, which are proteins of animal origin; sericin and other compounds of natural origin; and polyvinyl alcohol, polyacrylic acid, and polyacrylamide.

Besides the binding material(s) such as starch, the binding material particles C2 may contain constituents that do not have the function of joining fibers together even when supplied with water. Examples of such constituents include coloring materials, such as pigments, dyes, and toner, and fiber materials.

Preferably, the starch content of the binding material particles C2 is <NUM>% by mass or more, more preferably <NUM>% by mass or more, even more preferably <NUM>% by mass or more of the total mass of the binding material particles C2.

The complex C10 may contain binding material particles C2 with no inorganic oxide particle C3 adhering thereto, or, in other words, binding material particles C2 not forming composite particles C1. It is, however, preferred that the percentage of binding material particles C2 forming composite particles C1 be <NUM>% by mass or more, more preferably <NUM>% by mass or more, even more preferably <NUM>% by mass or more of the total mass of binding material particles C2 in the complex C10.

The inorganic oxide particles C3 prevent the aggregation of the composite particles C1 by being present on the surface of the binding material particles C2. Preferably, the average particle diameter of the inorganic oxide particles C3 is <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less.

This further reduces the aggregation of the composite particles C1 and, at the same time, improves their flowability by ensuring their surface roughness will not be too large. The inorganic oxide particles C3 in that case, furthermore, easily adhere to the surface of the binding material particles C2 and do not easily detach from the surface of the binding material particles C2.

The complex C10 may contain inorganic oxide particles C3 not adhering to binding material particles C2, or, in other words, inorganic oxide particles C3 not forming composite particles C1. It is, however, preferred that the percentage of inorganic oxide particles C3 forming composite particles C1 be <NUM>% by mass or more, more preferably <NUM>% by mass or more, even more preferably <NUM>% by mass or more of the total mass of inorganic oxide particles C3 in the complex C10.

The base particle of the inorganic oxide particles C3 contains an inorganic oxide. Owing to the presence of the inorganic oxide in their base particle, the inorganic oxide particles C3 have improved heat resistance.

Examples of materials for the base particle of the inorganic oxide particles C3 include metal oxides, such as silica, alumina, titania, zirconia, magnetite, and ferrite; and glass materials, such as soda-lime glass, glass-ceramics, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass. Of these materials, silica is particularly preferred; it improves the adhesion between the base particle and a coating layer derived from surface treatment agent(s). Silica, furthermore, is suitable for the production of sheet-shaped articles by virtue of its limited impact on the color of shaped articles made therewith.

The base particle of the inorganic oxide particles C3 may contain organic substances and/or inorganic substances other than inorganic oxides, such as metal nitrides, metal sulfides, and metal carbides. Preferably, the inorganic oxide content is <NUM>% by mass or more, more preferably <NUM>% by mass or more, even more preferably <NUM>% by mass or more of the total mass of the base particle of the inorganic oxide particles C3.

Preferably, the inorganic oxide particles C3 have a coating layer produced by surface treatment on the surface of their base particle. Preferably, the coating layer is formed using a surface treatment agent, such as a fluorine-containing compound or silicon-containing compound. This further prevents the aggregation of the binding material particles C2 and that of the composite particles C1. The flowability and the ease of handling of the complex C10, furthermore, are improved, and this will improve productivity in the production of the shaped article. Such a coating layer, furthermore, efficiently reduces the surface free energy of the inorganic oxide particles C3, thereby improving the wettability of the complex C10 on the fibers.

Examples of fluorine compounds as surface treatment agents include perfluoropolyether and fluorinated silicone oil.

Examples of silicon-containing compounds as surface treatment agents include silicone compounds, such as trimethylsilyl-terminated polydimethylsiloxane, hydroxy-terminated polydimethylsiloxane, polymethylphenylsiloxane, amino-modified silicone oil, epoxy-modified silicone oil, carboxy-modified silicone oil, carbinol-modified silicone oil, polyether-modified silicone oil, and alkyl-modified silicone oil.

Of these various silicones, it is particularly preferred to use trimethylsilyl-terminated polydimethylsiloxane. In other words, it is preferred that the coating layer on the base particle of the inorganic oxide particles C3 have trimethylsilyl groups on its surface. This further prevents the aggregation of the inorganic oxide particles C3, that of the binding material particles C2, and that of the composite particles C1.

Preferably, the coating layer of the inorganic oxide particles C3 contains <NUM>% by mass or more carbon in relation to the total mass of the inorganic oxide particles C3. This reduces the number of hydroxyl groups on the surface of the inorganic oxide particles C3, thereby lowering the hydrophilicity of the surface. As a result, for example, water absorption in the inorganic oxide particles C3, for example while in storage, will be reduced.

One such surface treatment agent alone or a combination of multiple ones may be used. When multiple surface treatment agents are used, each single base particle may be treated with the multiple ones. Alternatively, each single base particle may be treated with one of the surface treatment agents so that there will be a mixture of inorganic oxide particles C3 treated with different agents.

Preferably, the complex C10 meets the following conditions besides the foregoing.

It is preferred that the binding material particles C2 content of the complex C10 be <NUM>% by mass or more and <NUM>% by mass or less, more preferably <NUM>% by mass or more and <NUM>% by mass or less, even more preferably <NUM>% by mass or more and <NUM>% by mass or less of the total mass of the complex C10. This further improves the strength of the shaped article.

It is preferred that the inorganic oxide particles C3 content of the complex C10 be <NUM>% by mass or more and <NUM>% by mass or less, more preferably <NUM>% by mass or more and <NUM>% by mass or less, even more preferably <NUM>% by mass or more and <NUM>% by mass or less of the total mass of the complex C10. This further prevents the aggregation of the composite particles C1.

As illustrated in <FIG>, a method according to this embodiment for producing a shaped article includes a material-feeding step; a crushing step; a defibrating step; a screening step; a first web forming step; a dividing step; a mixing step; a disintegrating step; a second web forming step, which is the deposition step; a moistening step; a sheet-forming step, which is the shaping step; and a cutting step.

In the method for producing a shaped article, a sheet-shaped article is produced through these steps in the indicated order, from the upstream material-feeding step to the downstream cutting step. It should be noted that the method according to an aspect of the present disclosure for producing a shaped article includes a deposition step, a moistening step, and a shaping step, and no other step needs to be as listed above. Of the steps in the method according to this embodiment for producing a shaped article, the second web forming, moistening, and sheet-forming steps will now be outlined first.

In the second web forming step, a mixture containing a complex C10 and fibers is deposited in the air, the complex C10 containing a binding material. That is, the method according to an aspect of the present disclosure for producing a shaped article is one that relates to dry shaping.

Preferably, the complex C10 content of the mixture is, for example, <NUM>% by mass or more and <NUM>% by mass or less, more preferably <NUM>% by mass or more and <NUM>% by mass or less, even more preferably <NUM>% by mass or more and <NUM>% by mass or less of the total mass of the mixture.

This ensures the fiber content of the shaped article will be maintained relatively high and helps improve the strength of the shaped article at the same time. In the production process for the shaped article, furthermore, the transportability of the mixture is improved.

The fibers in the mixture may be supplied with water beforehand, for example before the moistening step described below. In that case, it is preferred that the water content of the fibers supplied with water beforehand be <NUM>% by mass or more and <NUM>% by mass or less, more preferably <NUM>% by mass or more and <NUM>% by mass or less, even more preferably <NUM>% by mass or more and <NUM>% by mass or less of the total mass of the fibers.

This helps prevent the fibers from being affected by static electricity upstream of the second web forming step. More precisely, electrostatic adhesion of the fibers, for example to walls of the production system for the shaped article, is reduced. In the preparation of the mixture, furthermore, the fibers and the complex C10 are mixed together with reduced unevenness in distribution. Alternatively, the fibers may be supplied with water between the preparation of the mixture and the sheet-forming step.

The fibers are the main constituent of the shaped article produced by the method for producing a shaped article. The fibers contribute greatly to the shaped article's ability to hold its shape and have great impact on the strength and other characteristics of the shaped article at the same time.

Preferably, the fibers contain a material having one or more kinds of the following functional groups: hydroxyl, carbonyl, and amino. This encourages the formation of hydrogen bonds between the fibers and the starch in the complex C10. The strength of bonding between the fibers and the starch, therefore, is improved, and the strength of the shaped article will be further improved. Preferably, the fibers are able to maintain their shape as fibers by being heated in the sheet-forming step.

The fibers may be synthetic fibers, i.e., fibers containing a synthetic resin, such as polypropylene, polyester, or polyurethane. It is, however, preferred that the fibers be of natural origin, or of biomass origin, for example for environmental and resource preservation reasons.

Of fibers of biomass origin, it is more preferred that the fibers be of cellulose in particular. The cellulose fiber is of plant origin and is a relatively abundant natural material. By using cellulose fibers, therefore, the manufacturer can accelerate its efforts to handle environmental issues, preserve underground resources, etc. The cellulose fiber, furthermore, is superior in raw material availability and cost. The cellulose fiber, moreover, contributes to improving the strength of the shaped article, too, with its particularly high theoretical strength surpassing that of other fibers.

The cellulose fibers, although primarily cellulose, may contain constituents other than cellulose. Examples of constituents other than cellulose include hemicellulose and lignin. The cellulose fibers may have been treated, for example by bleaching.

The fibers may have been treated, for example by ultraviolet irradiation, ozonation, or plasma treatment. These treatments produce functional groups, such as hydroxyl groups, on the surface of the fibers. The hydrophilicity of the fibers, therefore, is increased, and the fibers become more compatible with the starch.

Preferably, the average length of the fibers is, for example, <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, even more preferably <NUM> or more and <NUM> or less. This improves, for instance, stability in the shape of the shaped article.

Preferably, the average thickness of the fibers is, for example, <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less. This improves, for instance, stability in the shape of the shaped article. The smoothness of the surface of the shaped article is also improved.

Preferably, the average aspect ratio, i.e., the ratio of the average length to the average thickness, of the fibers is, for example, <NUM> or higher and <NUM> or lower, more preferably <NUM> or higher and <NUM> or lower. This improves, for instance, stability in the shape of the shaped article. The smoothness of the surface of the shaped article is also improved.

In the moistening step, the mixture is supplied with water. The water supplied to the mixture will be used by the starch to gelatinize. Supplying water and applying heat in the subsequent sheet-forming step will cause the starch to gelatinize and join the fibers together.

Examples of how to supply water to the mixture include exposing the mixture to a high-humidity atmosphere and exposing the mixture to a mist containing water. In the moistening step, one such method alone or a combination of multiple ones is used. More precisely, water is supplied using, for example, a humidifier, such as a steam vaporizer or ultrasonic humidifier.

The amount of water supplied to the mixture in the moistening step is <NUM>% by mass or more and <NUM>% by mass or less, more preferably <NUM>% by mass or more and <NUM>% by mass or less, even more preferably <NUM>% by mass or more and <NUM>% by mass or less of the total mass of the mixture.

As stated above, the gelatinization temperature of the starch is controlled by virtue of a reduced alkali metal salt content, and this accelerates the gelatinization of the starch. Even though the above ranges of amounts of water supplied are significantly small compared with those in known wet sheet-making processes, therefore, it is easy to gelatinize the starch. This helps make the production method suitable for dry shaping.

Water may also be supplied to the mixture in step(s) other than the moistening step. The water supplied to the mixture may contain constituents other than water, such as a preservative, an antimold, and/or a pesticide.

The sheet-forming step includes a heating step and a pressing step. In the sheet-forming step, heat and pressure are applied to the mixture supplied with water to give a shaped article. The heat applied to the mixture accelerates the gelatinization of the starch in the mixture, and the gelatinized starch joins the fibers in the mixture together. Pressure is applied to the mixture, or the mixture is pressed, at the same time to turn the shaped article into the desired shape, for example the shape of a sheet. The above moistening step and the sheet-forming step may be performed in parallel. In the sheet-forming step, furthermore, the heating and pressing steps may be carried out separately.

Preferably, the heating temperature, to which the mixture is heated in the sheet-forming step, is <NUM> or above and <NUM> or below, more preferably <NUM> or above and <NUM> or below, even more preferably <NUM> or above and <NUM> or below. This prevents the fibers and the complex C10 in the mixture from being degraded, altered, or otherwise affected by excessive heating. The flowability of the complex C10, furthermore, is increased, and the complex C10 wets and spreads better over the fibers. As a result, the quality of the shaped article will be improved. The increased gelatinizability of the starch, furthermore, allows for a low heating temperature, which is also advantageous as it helps reduce the energy requirements for the heating.

Preferably, the pressure applied to the mixture in the sheet-forming step is <NUM> MPa or more and <NUM> MPa or less, more preferably <NUM> MPa or more and <NUM> MPa or less, even more preferably <NUM> MPa or more and <NUM> MPa or less. This limits damage to and breakage of the fibers in the mixture, thereby helping further improve the strength of the shaped article.

A specific example of a method for producing a shaped article will now be described together with a production system for the shaped article. It should be noted that the production system for a shaped article described below is merely an example; the system does not need to be as described below.

As illustrated in <FIG>, the sheet-making system <NUM>, which produces a sheet-shaped article, includes a material-feeding section <NUM>, a crushing section <NUM>, a defibrating section <NUM>, a screening section <NUM>, a first web forming section <NUM>, a shredding section <NUM>, a mixing section <NUM>, a disintegrating section <NUM>, a second web forming section <NUM>, a sheet-forming section <NUM>, a cutting section <NUM>, and a stock section <NUM>. In the following, the terms above and below, up and down, side by side, etc., are based on directions in <FIG>. Being on the right in <FIG> may be described with the term downstream.

The sheet-making system <NUM> also includes moistening units <NUM>, <NUM>, <NUM>, and <NUM>. The sheet-making system <NUM>, furthermore, includes a control unit, not illustrated. The control unit centrally controls each component of the sheet-making system <NUM>.

At the material-feeding section <NUM>, the material-feeding step is performed. The material-feeding section <NUM> feeds a sheet-shaped material M1 to the crushing section <NUM>. The sheet-shaped material M1 is, for example, ordinary paper containing cellulose or other fibers.

At the crushing section <NUM>, the crushing step is performed. The crushing section <NUM> crushes the sheet-shaped material M1 fed from the material-feeding section <NUM> in a gas, for example in the air. The crushing section <NUM> has a pair of crushing blades <NUM> and a hopper <NUM>.

The pair of crushing blades <NUM> rotate in opposite directions and crush the sheet-shaped material M1 while it passes between the pair of crushing blades <NUM>. By the pair of crushing blades <NUM>, the sheet-shaped material M1 is broken into fragments M2. Preferably, the shape of the fragments M2 is one suitable for the defibration at the defibrating section <NUM>, such as small pieces measuring <NUM> or more and <NUM> or less in length.

The hopper <NUM> is below the pair of crushing blades <NUM>. The hopper <NUM> is substantially funnel-shaped, tapered at its bottom. This allows the hopper <NUM> to receive and collect the fragments M2 produced by the pair of crushing blades <NUM> and falling down.

Above the hopper <NUM> is a moistening unit <NUM> placed side-by-side with the pair of crushing blades <NUM>. The moistening unit <NUM> moistens the fragments M2 inside the hopper <NUM>. The moistening unit <NUM> includes a steam vaporizer and, although not illustrated, has a water-dampened filter. By passing air through the filter, humidified air is produced and fed to the fragments M2. This reduces static charge on the fragments M2, ensuring the fragments M2 will not easily adhere, for example to the hopper <NUM>.

The hopper <NUM> is coupled to the defibrating section <NUM> by a tube <NUM>, which is a pathway for the transportation of the fragments M2. The fragments M2 collected at the hopper <NUM>, therefore, are transported to the defibrating section <NUM> through the tube <NUM>.

At the defibrating section <NUM>, the defibrating step is performed. The defibrating section <NUM> defibrates the fragments M2 in a gas, for example in the air, or, in other words, dry-defibrates the fragments M2. Through the defibration at the defibrating section <NUM>, defibrated fibers M3 are produced from the fragments M2. In this context, defibration refers to separating the fragments M2, each of which is an assembly of multiple fibers bound together, into individual fibers. The defibrated fibers M3, therefore, are individual fibers separated out of the fragments M2. The shape of the defibrated fibers M3 is flakes or strips. The defibrated fibers M3, furthermore, may include masses of fibers entangled together, or may have formed "lumps.

Between the defibrating section <NUM> and the screening section <NUM> are a blower <NUM> and a tube <NUM>. The blower <NUM> is a device that produces a stream of gas. By rotating its rotor, not illustrated, the blower <NUM> produces a gas stream that sucks the fragments M2 from the hopper <NUM> into the defibrating section <NUM> via the tube <NUM>. By the gas stream, furthermore, the defibrated fibers M3 are transported to the screening section <NUM> via the tube <NUM>.

At the screening section <NUM>, the screening step is performed. The screening section <NUM> screens the defibrated fibers M3 according to the length of fibers and/or the size of fiber masses. At the screening section <NUM>, the defibrated fibers M3 are divided into first screened fibers M4-<NUM> and second screened fibers M4-<NUM>, which are larger than the first screened fibers M4-<NUM>. The first screened fibers M4-<NUM> have a size suitable for use as a material for the sheets S, which are the shaped article. The second screened fibers M4-<NUM> include, for example, insufficiently defibrated fibers and too large aggregates of defibrated fibers.

The screening section <NUM> has a drum <NUM> and a housing <NUM>. The housing <NUM> contains the drum <NUM>. The defibrated fibers M3 flow into the drum <NUM>.

The drum <NUM> is cylindrical, and the wall of the cylinder is mesh. The drum <NUM> rotates around its central axis. The meshed wall of the drum <NUM> functions as a sieve. As the drum <NUM> rotates, the defibrated fibers M3 in the drum <NUM> pass through the mesh as first screened fibers M4-<NUM> when smaller than the mesh openings and remain inside the drum <NUM> to be second screened fibers M4-<NUM> when larger than the mesh openings.

The first screened fibers M4-<NUM> pass through the meshed wall of the drum <NUM>. After that, the first screened fibers M4-<NUM> fall down while dispersing in the air inside the housing <NUM>. Below the drum <NUM> is a first web forming section <NUM>.

A moistening unit <NUM> is coupled to the housing <NUM>. The moistening unit <NUM> includes a steam vaporizer similar to that of the moistening unit <NUM>. By the moistening unit <NUM>, humidified air is fed into the housing <NUM>. Static charge on the first screened fibers M4-<NUM>, therefore, is reduced, ensuring the first screened fibers M4-<NUM> will not easily adhere, for example to the inner walls of the housing <NUM>.

The second screened fibers M4-<NUM> are transported to a tube <NUM> connecting to the inside of the drum <NUM>. The tube <NUM> extends from the drum <NUM> and is coupled to the tube <NUM>. The second screened fibers M4-<NUM>, therefore, are transported from the tube <NUM> to the tube <NUM> and mixed with the fragments M2 in the tube <NUM>. That is, the second screened fibers M4-<NUM> are defibrated again at the defibrating section <NUM>.

At the first web forming section <NUM>, the first web forming step is performed. The first web forming section <NUM> forms a first web M5 from the first screened fibers M4-<NUM>. The first web forming section <NUM> has a mesh belt <NUM>, which is a separating belt; three tension rollers <NUM>; and an aspirator <NUM>.

The mesh belt <NUM> is an endless belt that is a piece of mesh. The mesh openings in the mesh belt <NUM> are smaller than the first screened fibers M4-<NUM>. The first screened fibers M4-<NUM> that fall down from the drum <NUM>, therefore, do not pass through the mesh openings in the mesh belt <NUM> but accumulate on the mesh belt <NUM>.

The mesh belt <NUM> is wound around three tension rollers <NUM>. As the tension rollers <NUM> are driven to rotate, the mesh belt <NUM> transports the deposit of first screened fibers M4-<NUM> thereon downstream by rotating clockwise in <FIG>. The screening step, at the screening section <NUM>, and the rotation of the mesh belt <NUM> proceed in parallel and continuously. The first screened fibers M4-<NUM> that accumulate on the mesh belt <NUM>, therefore, are layered, forming a first web M5.

In this step, any dust, for example, in the first screened fibers M4-<NUM> is eliminated as it passes through the mesh openings in the mesh belt <NUM> and falls down from the mesh belt <NUM>. Such dust can enter the system together with the sheet-shaped material M1, for example when the sheet-shaped material M1 is fed from the material-feeding section <NUM> to the crushing section <NUM>.

Below the housing <NUM> is an aspirator <NUM>, facing the housing <NUM> with the mesh belt <NUM> therebetween. In side view, the aspirator <NUM> is inside the mesh belt <NUM> wound around the three tension rollers <NUM>. The aspirator <NUM> pulls the air in the housing <NUM> above it through the portion of the mesh belt <NUM> facing the housing <NUM>.

The air pulled by the aspirator <NUM> attracts the first screened fibers M4-<NUM> to the upper surface of the mesh belt <NUM>, accelerating the formation of the first web M5 on the mesh belt <NUM>. The aforementioned dust, furthermore, is sucked through the mesh belt <NUM>. The aspirator <NUM> is coupled to a trap <NUM> by a tube <NUM>. The dust sucked into the aspirator <NUM> is collected in the trap <NUM>.

A tube <NUM> and a blower <NUM> are also coupled to the trap <NUM>. The blower <NUM> provides the suction at the aspirator <NUM>. That is, the blower <NUM> causes the aspirator <NUM> to suck the air present above it by acting on it via the tube <NUM>, the trap <NUM>, and the tube <NUM>.

Downstream of the screening section <NUM> is a moistening unit <NUM>. The moistening unit <NUM> includes an ultrasonic humidifier and moistens the first web M5 by sending water mist to it. The water content of the first web M5, therefore, is adjusted. Static charge on the first web M5 is reduced, inhibiting electrostatic adhesion of the first web M5 to the mesh belt <NUM>. This makes it easier to peel the first web M5 off the mesh belt <NUM> at the downstream end of the mesh belt <NUM>.

Downstream of the moistening unit <NUM> is a shredding section <NUM>. At the shredding section <NUM>, the dividing step is performed. The shredding section <NUM> divides the first web M5 peeled off from the mesh belt <NUM>. The shredding section <NUM> has a rotatably supported propeller <NUM> and a housing <NUM> that contains the propeller <NUM>. A rotating propeller <NUM> touches the first web M5, dividing the first web M5. The first web M5 is divided into shreds M6. The shreds M6 fall down inside the housing <NUM>.

A moistening unit <NUM> is coupled to the housing <NUM>. The moistening unit <NUM> includes a steam vaporizer similar to that of the moistening unit <NUM>. By the moistening unit <NUM>, humidified air is fed into the housing <NUM>. Static charge on the first shreds M6, therefore, is reduced, ensuring the shreds M6 will not easily adhere, for example to the inner walls of the housing <NUM> or the propeller <NUM>.

Downstream of the shredding section <NUM> is a mixing section <NUM>. At the mixing section <NUM>, the mixing step is performed. The mixing section <NUM> mixes the shreds M6 and the complex C10 together. The mixing section <NUM> has a complex feeder <NUM>, a tube <NUM>, and a blower <NUM>.

The tube <NUM> connects the bottom of the housing <NUM> and the housing <NUM> of the disintegrating section <NUM>. The shreds M6 and a mixture M7 of the shreds M6 and the complex C10 pass through the tube <NUM>.

The complex feeder <NUM> is coupled to the tube <NUM> between the housing <NUM> and the blower <NUM>. The complex feeder <NUM> has a feeding screw <NUM>. As the feeding screw <NUM> is driven to rotate, the complex C10 is fed from the complex feeder <NUM> into the tube <NUM>. When the complex C10 is fed into the tube <NUM>, the complex C10 and the shreds M6 are mixed together to give a mixture M7.

The complex C10 fed into the tube <NUM> may contain, for example, a colorant that colors the fibers, an aggregation inhibitor that reduces the aggregation of the fibers and that of the complex C10, and/or a flame retardant that renders the fibers fireproof.

The blower <NUM> is on the tube <NUM> and located downstream of where the complex feeder <NUM> is coupled to it. The blower <NUM> produces a stream of gas inside the tube <NUM>, a gas stream that moves toward the disintegrating section <NUM>. The gas stream transports the shreds M6 and the complex C10 inside the tube <NUM> to the disintegrating section <NUM> while stirring them. By virtue of the blower <NUM>, unevenness in the distribution of the shreds M6 and the complex C10 in the mixture M7 is reduced.

The disintegrating section <NUM> is downstream of the tube <NUM>. At the disintegrating section <NUM>, the disintegrating step is performed. The disintegrating section <NUM> disintegrates masses of entangled fibers in the mixture M7 into smaller pieces. The disintegrating section <NUM> has a drum <NUM> and a housing <NUM> that contains the drum <NUM>. The tube <NUM> connects to the inside of the drum <NUM>, and the mixture M7 flows into the drum <NUM>.

The drum <NUM> is cylindrical, and the wall of the cylinder is mesh. The drum <NUM> rotates around its central axis. The meshed wall of the drum <NUM> functions as a sieve. As the drum <NUM> rotates, the mixture M7 inside the drum <NUM> is disintegrated, and fibers smaller than the mesh openings pass through the mesh of the drum <NUM>.

The part of the mixture M7 that has passed through the mesh of the drum <NUM> falls down below the drum <NUM> while dispersing in the air inside the housing <NUM>. Below the drum <NUM> is a second web forming section <NUM>.

A moistening unit <NUM> is coupled to the housing <NUM>. The moistening unit <NUM> includes a steam vaporizer similar to that of the moistening unit <NUM>. Humidified air is fed from the moistening unit <NUM> into the housing <NUM>. Static charge on the mixture M7, therefore, is reduced, ensuring the mixture M7 will not easily adhere, for example to the inner walls of the housing <NUM>.

At the second web forming section <NUM>, the second web forming step is performed. The second web forming section <NUM> forms a second web M8 from the mixture M7. The second web forming section <NUM> has a mesh belt <NUM>, which is a separating belt; four tension rollers <NUM>; and an aspirator <NUM>.

The mixture M7 falls down from the drum <NUM> onto the upper surface of the mesh belt <NUM>. The mesh belt <NUM> is an endless belt that is a piece of mesh. The mesh openings in the mesh belt <NUM> are smaller than most of the fibers in the mixture M7 falling down from the drum <NUM>. The mixture M7, therefore, does not pass through the mesh openings in the mesh belt <NUM> but accumulates on the upper surface of the mesh belt <NUM>.

The mesh belt <NUM> is wound around four tension rollers <NUM>. As the tension rollers <NUM> are driven to rotate, the mesh belt <NUM> transports the deposit of the mixture M7 thereon downstream by rotating clockwise in <FIG>. The disintegrating step, at the disintegrating section <NUM>, and the rotation of the mesh belt <NUM> proceed in parallel and continuously. The part of the mixture M7 that accumulates on the mesh belt <NUM>, therefore, is layered, forming a second web M8.

Below the housing <NUM> is an aspirator <NUM>, facing the housing <NUM> with the mesh belt <NUM> therebetween. In side view, the aspirator <NUM> is inside the mesh belt <NUM> wound around the four tension rollers <NUM>. The aspirator <NUM> is coupled to a blower <NUM> by a tube <NUM>.

The blower <NUM> provides the suction at the aspirator <NUM>. That is, the blower <NUM> causes the aspirator <NUM> to suck the air present above it by acting on it via the tube <NUM>. As a result of this, the aspirator <NUM> pulls the air inside the housing <NUM> above it through the portion of the mesh belt <NUM> facing the housing <NUM>. The formation of the second web M8 on the mesh belt <NUM>, therefore, is accelerated.

Downstream of where the housing <NUM> and the mesh belt <NUM> face each other is a moistening unit <NUM>. Like the moistening unit <NUM>, the moistening unit <NUM> includes an ultrasonic humidifier and moistens the second web M8 by sending water mist to it. The water content of the second web M8, therefore, is adjusted, and the strength of bonding between the fibers and the complex C10 in the resulting sheet S will be improved. Static charge on the second web M8, furthermore, is reduced, ensuring the second web M8 will not easily adhere to the mesh belt <NUM>. This makes it easier to peel the second web M8 off the mesh belt <NUM> at the downstream end of the mesh belt <NUM>.

Downstream of the second web forming section <NUM> is a sheet-forming section <NUM>. At the sheet-forming section <NUM>, the sheet-forming step is performed. The sheet-forming section <NUM> has a heat press <NUM>. The second web M8 peeled off from the mesh belt <NUM> is transported to the sheet-forming section <NUM>.

The heat press <NUM> has a pair of heating rollers <NUM>. In the sheet-forming step, the pair of heating rollers <NUM> is used to shape the second web M8 into a sheet S.

The passage of the second web M8 between the pair of heating rollers <NUM> causes the second web M8 to be pressed while being heated. Each of the pair of heating rollers <NUM> has a built-in heater, not illustrated. The heater increases the surface temperature of the heating roller <NUM>.

By the pair of heating rollers <NUM>, heat and pressure are applied to the second web M8 in parallel. That is, at the pair of heating rollers <NUM>, heating and pressing are performed simultaneously. More precisely, in the steps before the sheet-forming step, the second web M8 is not subjected to heating to a temperature higher than the temperature to which the pair of heating rollers <NUM> heats it. Likewise, in the steps before the sheet-forming step, the second web M8 is not subjected to the application of a pressure higher than the pressure the pair of heating rollers <NUM> applies to it.

This turns the second web M8 into a sheet S as a result of the starch in the complex C10 melting and joining the fibers together. The parallel pressing and heating of the second web M8 performed by the pair of heating rollers <NUM> encourages bonding between the fibers, improving the strength of the sheet S. The production process for the sheet S, furthermore, is streamlined. Because the pair of heating rollers <NUM> alone is used to perform heating and pressing, moreover, the setup is simple and can be easily made in a compact design compared with when heating and pressing are conducted using separate devices.

Preferably, the surface temperature of each heating roller <NUM> is <NUM> or above and <NUM> or below. This limits, for example, the degradation of the fibers in the second web M8. The starch, furthermore, gelatinizes, further encouraging bonding between the fibers.

As stated, it is preferred that the pressure applied by the pair of heating rollers <NUM> to the second web M8, formed from the mixture M7, be <NUM> MPa or more and <NUM> MPa or less, more preferably <NUM> MPa or more and <NUM> MPa or less, even more preferably <NUM> MPa or more and <NUM> MPa or less. This allows the starch to wet and spread better over the surface of the fibers, further encouraging bonding between the fibers.

One of the pair of heating rollers <NUM> is a driving roller powered by a motor, not illustrated, and the other is a driven roller. The second web M8 turns into a sheet S by passing through the heat press <NUM> in the sheet-forming section <NUM> and is transported to the downstream cutting section <NUM>.

At the cutting section <NUM>, the cutting step is performed. The cutting section <NUM> cuts the sheet S into the desired shape. The cutting section <NUM> has a first cutter <NUM> and a second cutter <NUM>. In the cutting section <NUM>, the first cutter <NUM> is closer to the sheet-forming section <NUM>, and the second cutter <NUM> is downstream.

The first cutter <NUM> cuts the sheet S transversely with respect to the direction of transport of the sheet S. The second cutter <NUM> cuts the sheet S in the direction parallel to the direction of transport of the sheet S. By the first and second cutters <NUM> and <NUM>, the sheet S is trimmed to its intended shape. Then the sheet S is stored in a stock section <NUM> placed downstream of the cutting section <NUM>. In this way, a sheet S is produced.

Although sheets S have been featured as an example of a shaped article in this embodiment, this is not the only possible shape of the shaped article produced by the method according to an aspect of the present disclosure for producing a shaped article. Examples of shapes of the shaped article include various ones, such as blocks, spheres, and three-dimensional solids, besides sheets. Of these, the method according to an aspect of the present disclosure for producing a shaped article and the binder according to another are suitable for producing a sheet-shaped article by virtue of their ability to improve the strength of the shaped article.

When the shaped article is sheets S, it is preferred that the density of the sheets S is <NUM>/cm<NUM> or more and <NUM>/cm<NUM> or less. This makes, for example, the sheets S a suitable recording medium for inkjet recording. Besides recording media, furthermore, the sheets S may be used as a liquid absorbent, a buffering material, a sound absorber, etc., after treatment.

According to this embodiment, the following advantages are obtained.

In dry shaping, the strength of sheets S produced from fibers and a complex C10 is improved. More precisely, the gelatinization temperature of starch is stabilized by virtue of a limited alkali metal salt content of the starch, and this makes it easier to control the gelatinization temperature. The gelatinization temperature, therefore, is controlled, and bonding between the fibers in the mixture M7 through the gelatinization of the starch is encouraged. This improves the strength of the sheets S. Overall, this embodiment provides a method, for producing a shaped article, that improves the strength of sheets S in dry shaping and also provides the complex C10 as a binder.

The advantages of aspects of the present disclosure will now be more specifically described by providing examples and comparative examples. For Examples <NUM> to <NUM> and Comparative Examples <NUM> to <NUM>, sheets S that were shaped articles were prepared and evaluated. Hereinafter, Examples <NUM> to <NUM> may be collectively referred to simply as the Examples, and Comparative Examples <NUM> to <NUM> may be collectively referred to simply as the Comparative Examples. It should be noted that no aspect of the present disclosure is limited by these Examples.

For each level of the Examples and Comparative Examples, the starch used and its specifications, the inorganic oxide particles C3 used, parameters in the production process for the shaped article, and the strength grade of the shaped article are presented in Tables <NUM> and <NUM>. In Tables <NUM> and <NUM>, the details of the starches and the inorganic oxide particles C3 are as follows.

Starches were prepared and analyzed/measured by the following methods. First, starches <NUM> and <NUM> were pretreated by crushing. Specifically, each of starches <NUM> and <NUM> was crushed using Hosokawa Micron's fluidized-bed opposed jet mill Counter Jet Mill AFG-R, giving binding material particles C2. For starch <NUM> or <NUM> in the Examples excluding Examples <NUM> and <NUM>, the air pressure of the mill during crushing was set to <NUM> kPa. For starch <NUM> in Example <NUM>, this air pressure was set to <NUM> kPa, and for starch <NUM> in Example <NUM>, this air pressure was set to <NUM> kPa.

To starch <NUM> in Comparative Example <NUM>, a predetermined amount of FUJIFILM Wako Chemicals' sodium chloride was added as an alkali metal salt before the crushing. After that, the starch was crushed in the same way as the starches in the Examples. To starch <NUM> in Comparative Example <NUM>, a predetermined amount of FUJIFILM Wako Chemicals' potassium chloride was added as an alkali metal salt before the crushing. After that, the starch was crushed in the same way as the starches in the Examples. To starch <NUM> in Comparative Example <NUM>, a predetermined amount of FUJIFILM Wako Chemicals' sodium sulfate was added as an alkali metal salt before the crushing. After that, the starch was crushed in the same way as the starches in the Examples.

For each of the crushed starches in the Examples and Comparative Examples, the average particle diameter of particles of the starch was measured by the method described above. The results are presented in Tables <NUM> and <NUM>.

Using Rigaku's TG-DTA (thermogravimetry-differential thermal analysis) system TG8121, each starch was thermally decomposed at <NUM> for <NUM> minutes in an atmosphere of inert gases including nitrogen and helium. Then the residue from thermal decomposition was qualitatively and quantitatively analyzed by energy dispersive x-ray spectroscopy (EDS). Alkali metal salts in the binding material were identified and quantified based on the mass of the starch before the TG-DTA measurement, the mass of the residue from thermal decomposition, and the EDS analytical results.

The results of the analysis indicated each of the starches in the Examples contained the alkali metal salt of sodium chloride. For the starch in Comparative Example <NUM>, sodium chloride originally contained in starch <NUM> and sodium chloride added before crushing were detected.

For the starch in Comparative Example <NUM>, sodium chloride originally contained in starch <NUM> and potassium chloride added before crushing were detected. The alkali metal salt content of the starch in Comparative Example <NUM> is the sum of the original sodium chloride content of starch <NUM> and the amount of potassium chloride added before crushing.

For the starch in Comparative Example <NUM>, sodium chloride originally contained in starch <NUM> and sodium sulfate added before crushing were detected. The alkali metal salt content of the starch in Comparative Example <NUM> is the sum of the original sodium chloride content of starch <NUM> and the amount of sodium sulfate added before crushing. The alkali metal salt content of each starch is presented in Tables <NUM> and <NUM>.

For each of the starches in the Examples and Comparative Examples, the gelatinization temperature was measured using Rigaku's differential scanning calorimeter Thermo plus EVO DSC8231. Specifically, a solution prepared by mixing the starch and deionized water together in a ratio by mass of <NUM> in <NUM> was sealed in a pressure-resistant aluminum pan, and this solution was used as a sample for measurement. Then this sample for measurement was set in the calorimeter and analyzed by differential scanning calorimetry at a heating rate of <NUM> per minute. On each of the resulting DSC curves, the temperature at which the curve had the endothermic peak (temperature at the bottom of the peak) was read as the gelatinization temperature. The results are presented in Tables <NUM> and <NUM>. It should be noted that in Comparative Examples <NUM>, <NUM>, and <NUM>, the gelatinization temperature was indeterminable because the endothermic peak in the DSC curve was split.

A complex was prepared from each of the starches in the Examples excluding Example <NUM> and in the Comparative Examples. Specifically, the crushed starch and the inorganic oxide particles C3 were loaded into Nippon Coke & Engineering's Henschel mixer FM Mixer and mixed together at a frequency of <NUM> for <NUM> minutes. Then coarse particles larger than <NUM> were eliminated using a <NUM>-µm mesh sieve to complete the complex. In Example <NUM>, the crushed starch alone, without inorganic oxide particles C3 added, was handled in the same way for a processing similar to the preparation of the complex. That is, Example <NUM> is a level at which no complex was formed.

A shaped article was produced for each of the Examples and Comparative Examples. Specifically, the production system was a version of Seiko Epson's dry-process office papermaking system PaperLab A-<NUM> modified so that formed sheets could be moistened before processing. The sheet feeder of this system was loaded with used paper, as the aforementioned sheet-shaped material M1, prepared by printing a business document on FUJI XEROX's recycled copier paper GR-70W using an ink jet printer, and the system was configured for a grammage of <NUM>/m<NUM>.

Then cartridges of the system were each loaded with one of the complexes in Examples and the Comparative Examples or the processed starch in Example <NUM>. The cartridges were attached to the system one after another, and recycled sheets were produced that were shaped articles in the Examples and Comparative Examples. Parameters in the moistening and shaping steps during production were set to the values indicated in Tables <NUM> and <NUM>.

The shaped article in Example <NUM> is a level at which starch <NUM> and inorganic oxide particles A were used, the amount of water supplied in the moistening step was <NUM>% by mass, the heating temperature in the shaping step was <NUM>, and the pressure applied in the shaping step was <NUM> MPa.

Example <NUM>, compared with Example <NUM>, is a level at which starch <NUM> was used instead of starch <NUM>.

Examples <NUM>, <NUM>, <NUM>, and <NUM>, compared with Example <NUM>, is a level at which the heating temperature in the shaping step was changed.

Examples <NUM> and <NUM>, compared with Example <NUM>, is a level at which the pressure applied in the shaping step was changed.

Examples <NUM> and <NUM>, compared with Example <NUM>, is a level at which the amount of water supplied in the moistening step was changed.

Examples <NUM> and <NUM>, compared with Example <NUM>, is a level at which the average particle diameter was changed by adjusting the air pressure during the crushing.

Example <NUM>, compared with Example <NUM>, is a level at which no inorganic oxide particles were used; the starch did not form a complex.

Example <NUM>, compared with Example <NUM>, is a level at which inorganic oxide particles B were used instead of inorganic oxide particles A.

In Comparative Examples <NUM>, <NUM>, and <NUM>, compared with Example <NUM>, the alkali metal salt content of the starch was increased. Comparative Examples <NUM>, <NUM>, and <NUM> are levels at which the alkali metal salt content exceeded <NUM>% by mass of the total mass of the starch.

As a measure of the strength of the shaped articles, specific tensile strength was measured. Specifically, the tensile tester was Shimadzu's Autograph AGS-1N. Immediately after the production of a shaped article, a test specimen was prepared by cutting a <NUM>×<NUM> strip out of the shaped article. The test specimen was set on the tester, with the longitudinal axis of the test specimen aligned with the direction of stretch. Subsequently, the longitudinal fracture strength of the test specimen was measured at a tensile rate of <NUM> per second. The specific tensile strength was calculated from the measured fracture strength and the density of the shaped article and graded according to the following assessment criteria.

As shown in Tables <NUM> and <NUM>, the specific tensile strength in all Examples was within acceptable limits, graded <NUM> or better. In particular, in Examples <NUM>, <NUM>, <NUM>, and <NUM>, the grade was <NUM>, which corresponds to excellent, and in Examples <NUM> and <NUM>, the grade was <NUM>, which corresponds to good. This revealed the Examples improve the strength of shaped articles.

Claim 1:
A method for producing a shaped article, the method comprising:
a deposition step, in which a mixture containing fibers and a binding material is deposited in air, the binding material containing starch and an alkali metal salt;
a moistening step, in which the mixture is supplied with water; and
a shaping step, in which heat and pressure are applied to the mixture supplied with the water to give a shaped article (S), wherein:
an alkali metal salt content of the binding material is <NUM>% by mass or less of a total mass of the starch;
in the moistening step, an amount of the water supplied to the mixture is <NUM>% by mass or more and <NUM>% by mass or less of a total mass of the mixture;
an average particle diameter of the binding material is <NUM> or more and <NUM> or less, wherein the average particle diameter of the binding material is measured as disclosed in the present description; and
particles of the binding material include inorganic oxide particles integrated therewith..