JP7349083B2 - Manufacturing method of okara kneading resin - Google Patents

Description

The present invention relates to a method for producing an okara kneading resin in which okara generated during tofu production is kneaded into the resin.

Currently, some of the okara generated during the tofu manufacturing process is recycled for use in food, feed, and fertilizer, but much of it is disposed of as waste. However, as shown in FIG. 1, dried okara can absorb water vapor of 20% or more of its own weight at 25° C. and 90% R.H. relative humidity.

For this reason, utilizing the hygroscopicity of okara, Patent Document 1 proposes a method in which a glue is added to dried okara, formed into a plate by compression molding, and recycled as trays and folding boxes with excellent hygroscopicity. ing.

Furthermore, it has been proposed to knead food biomass into resin during molding for the purpose of imparting functionality such as antibacterial properties and improved strength. For example, Patent Document 2 discloses that a thermosetting or thermoplastic resin and food biomass such as okara, bran, coffee bean grounds, soybean grounds, soy sauce grounds, and beer grounds are stirred and mixed while heating at around 150°C. After that, a method of molding using an arbitrary molding method has been proposed.

Japanese Patent Application Publication No. 2-192904 Japanese Patent Application Publication No. 10-145055

However, in the method shown in Patent Document 1 mentioned above, in which a sizing agent is added to dried okara and compression molding is performed, there is a concern that the hygroscopicity of the okara may be inhibited by the sizing agent. In addition, because the bean curd curd is glued only with glue, it tends to disintegrate easily.

Furthermore, in Patent Document 2, the food biomass is dried because the resin and the food biomass are heated at around 150° C. during stirring and mixing. For this reason, there is a concern that the food biomass is likely to be scattered due to static electricity, resulting in poor handling, such as when a stirred mixture of resin and food biomass is fed into the hopper of a molding machine. Furthermore, since food biomass and resin have different true specific gravity, the larger the amount of food biomass kneaded, the more difficult it is to knead the food biomass and resin to a state where they do not separate.

The present invention seeks to solve the problems of the prior art as described above.

In order to achieve the above object, the present invention provides a new method for producing okara kneaded resin by heating, melting and kneading a mixture containing okara and resin. The present invention also provides a new okara kneading resin obtained by heat-melting and kneading okara and resin, in which the total weight ratio of okara and resin is 80% by weight or more. In a typical embodiment, in the production method of the present invention, a resin having a melting point of 220°C or less, such as polypropylene, polyethylene, polylactic acid, or polybutylene succinate, and okara, which is soybean residue produced during tofu production, are used. The okara kneaded resin is produced by heating and melt-kneading the mixture at 180° C. or higher and 220° C. or higher to obtain a kneaded product of okara and resin, followed by a step of cooling the kneaded product. The so-produced okara kneading resin may be further cut into lengths of 1 mm or more and 10 mm or less to obtain okara kneading resin pellets.

When the okara was thermogravimetrically measured (in an air atmosphere, at a heating rate of 10° C./min), as shown in FIG. 2, a rapid weight loss was confirmed in the temperature range of 220° C. or higher. For this reason, if the kneading temperature of bean curd and resin is 220° C. or lower, it is thought that thermal decomposition of bean curd will hardly occur.

At this time, the okara contained in the okara kneading resin contains water of 1% to 20% by weight and oil content of 1% to 15% by weight. Further, the weight ratio of bean curd curd curd curd curd curd lees contained in the bean curd curd kneading resin is 10% by weight or more and 70% by weight or less.

In addition, when kneading bean curd curd and resin, a kneader schematically shown in FIG. 3 is used. There is a concern that the moisture contained in the bean curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd (curd curd curd curd curd curd curd curd curd curd curd curd) is mixed with water vapor. In order to solve this problem, water vapor generated within the cylinder 1 is released to the outside of the cylinder 1 by providing an automatic exhaust valve 2 at an arbitrary location of the cylinder 1.

The present invention provides a novel method for producing okara kneaded resin by heating, melting, and kneading a mixture containing okara and resin. The present invention also provides a new okara kneading resin obtained by heating and melting kneading okara and resin, in which the total weight ratio of okara and resin is 80% by weight or more. The novel okara kneading resin of the present invention does not cause the okara and the resin to separate, and is suitable for manufacturing molded products. The novel okara kneading resin of the present invention also contains only a small amount of components other than okara and resin, and therefore can be easily produced.

According to the production method of the present invention, when kneading okara with resin, it is possible to knead okara into resin without adding a compatibilizer or the like, and the okara and resin do not separate.

The present invention not only reduces raw material costs by kneading food biomass and reducing the proportion of resin in molded products, but also reduces the amount of resin used, which can contribute to building a sustainable society. Useful.
In the embodiment of the present invention, the following items are provided, for example.
(Item 1)
heating and melting and kneading a mixture containing okara and resin to obtain a kneaded product of okara and resin;
cooling the kneaded material;
A method for producing okara kneading resin, comprising:
(Item 2)
The manufacturing method according to item 1, wherein the total weight proportion of the okara and the resin in the mixture is 80% by weight or more.
(Item 3)
The manufacturing method according to item 1, wherein the total weight proportion of the okara and the resin in the mixture is 90% by weight or more.
(Item 4)
The method for producing okara kneading resin according to any one of items 1 to 3, wherein the resin has as a main component one or more selected from polypropylene, polyethylene, polylactic acid, and polybutylene succinate.
(Item 5)
The method for producing okara kneading resin according to any one of items 1 to 4, wherein the okara contains an oil content of 1% by weight or more and 15% by weight or less.
(Item 6)
The method for producing okara kneading resin according to any one of items 1 to 5, wherein the okara contains water of 1% by weight or more and 20% by weight or less.
(Item 7)
The method for producing okara kneading resin according to any one of items 1 to 6, wherein the weight proportion of okara in the okara kneading resin is 10% by weight or more and 70% by weight or less.
(Item 8)
The method for producing okara kneading resin according to any one of items 1 to 7, characterized in that the heating melt-kneading is performed at a temperature of 180° C. or higher and 230° C. or lower.
(Item 9)
The method for producing an okara kneading resin according to any one of items 1 to 8, wherein the okara kneading resin is one in which the okara and the resin do not separate.
(Item 10)
The method for producing okara kneaded resin according to any one of items 1 to 9, further comprising the step of cutting the kneaded material into lengths of 1 mm or more and 10 mm or less to form pellets.
(Item 11)
A method for manufacturing a resin molded product, the method comprising:
A step of providing okara kneading resin by the method for producing okara kneading resin according to any one of items 1 to 10;
Processing the okara kneading resin to obtain a resin molded product;
A manufacturing method including:
(Item 12)
An okara kneading resin obtained by heat-melting and kneading okara and a resin, wherein the total weight proportion of the okara and the resin in the okara kneading resin is 80% by weight or more.
(Item 13)
The okara kneading resin according to item 12, wherein the total weight proportion of the okara and the resin in the kneading resin is 90% by weight or more.
(Item 14)
The okara kneading resin according to item 12 or 13, wherein the okara and the resin do not separate.
(Item 15)
Okara kneading resin produced by the method for producing okara kneading resin according to any one of items 1 to 10.
(Item 16)
Items 12 to 14, which have a water vapor adsorption amount of 3.5 mg, 7.5 mg, and 20 mg or more per 1 g of the okara kneading resin when measured at a measurement temperature of 25 ° C. and a relative humidity of 25%, 50%, and 90%, respectively. The okara kneading resin according to any one of the above.

It is a figure showing the water vapor adsorption isotherm of dried okara. It is a figure showing the thermogravimetric curve of dried okara. FIG. 2 is a diagram schematically showing a kneader used for kneading bean curd curd and resin. It is a figure which shows typically the flow of a kneading process, a cooling process by an air cooling system, and a cutting process. FIG. 2 is a diagram schematically showing the flow of a kneading process, a cooling process using a cooling block contact method, and a cutting process. FIG. 3 is a diagram schematically showing the flow of a kneading process, a water-cooling cooling process, and a cutting process. It is a figure which shows typically the pelletizer used in the cutting process.

Embodiments of the present invention will be described below. The embodiment described below describes an example of a preferred embodiment of the invention, and does not limit the constituent elements of the invention described in the claims. Any weight percentages described herein may be on a wet weight basis or on a dry weight basis, as appropriate.

(Properties of resin and okara to be kneaded)
(Resin material)
The type of resin to be kneaded with bean curd is preferably polypropylene, polyethylene, polylactic acid, or polybutylene succinate, each having a melting point of 220° C. or lower. Note that a plurality of types of these resins may be mixed. In particular, resins with similar solubility parameters (eg, polypropylene and polyethylene, polylactic acid and polybutylene succinate) are preferred because they are easy to mix. Examples of the mixed resin in the present invention include a resin containing polybutylene succinate and polylactic acid, or a resin containing polypropylene and polyethylene. The weight ratio of each resin in the mixed resin of multiple types may be arbitrary, but in one embodiment, the mixed resin of the present invention includes polybutylene succinate and polylactic acid, or polypropylene and polyethylene. It may contain 99:1 to 1:99. It is envisioned that polylactic acid, which is relatively hard and has low impact strength, may be blended with polybutylene succinate, which is a soft resin, to improve the impact strength of the resulting kneaded resin without losing its biodegradability. On the other hand, a resin with a melting point exceeding 220° C. is not suitable because thermal decomposition of okara becomes noticeable during melt-kneading (see FIG. 2). In this specification, when a resin "contains a certain component as a main component", it means that the weight proportion of the component in the resin is 70% by weight or more.

(Kneading ratio of okara)
Okara is the residue that remains when soy milk is squeezed during the process of producing tofu from soybeans, and is generated in large quantities during the tofu production process. The kneading ratio of okara in the okara kneading resin of the present invention is calculated by the following formula 1. The R, W1 and W2 in equation 1 represent the mixed ratio (weight %) of the kara, the dry weight (kg) of the mixture, and the dry weight (kg) of the resin.

Moreover, the kneading ratio of bean curd curd in the bean curd kneading resin is preferably 10% by weight or more, more preferably 25% by weight or more, and most preferably 30% by weight or more. When the kneading ratio of bean curd curd is less than 10% by weight, there is a concern that the bean curd lees will be buried in the resin and no significant difference will be observed in the hygroscopicity of the kneaded resin pellets. When the kneading ratio of okara increases, the resin tends to separate from the okara after being heated and melted and kneaded with the resin, and it is difficult to mix the okara uniformly.However, in the present invention, various conditions described below were considered. As a result, even if okara is kneaded with 10% by weight or more, 25% by weight or more, or 30% by weight or more, the okara and resin do not separate and/or are suitable for producing molded products. A kneaded resin or kneaded resin pellets with a high degree of uniformity could be obtained. In this specification, the product obtained after heating and melting and kneading a mixture of okara and resin is referred to as a "kneaded product", and the product obtained by cooling the kneaded product is referred to as a "okara kneaded resin" or a "kneaded product". Okara kneading resin or kneading resin cut into pellets is called "okara kneading resin pellets" or "kneading resin pellets."

When the kneading ratio of bean curd curd is more than 70% by weight, the bean curd lees easily peels off from the bean curd kneading resin, and the strength of the kneaded resin pellets is also low, making it difficult to use it practically as a bean curd kneading resin. Therefore, the kneading ratio of bean curd curd in the bean curd kneading resin may be 70% by weight or less, preferably 60% by weight or less, and more preferably 51% by weight or less. The kneading ratio of okara in the okara kneading resin of the present invention may be in a numerical range between any one of the lower limit values in the above paragraph and any one of the upper limit values described in this paragraph.

(Total weight ratio of okara and resin)
The present invention provides a bean curd kneading resin and a method for producing the same, in which bean curd curd and resin do not separate from each other even though the total weight ratio of bean curd curd and resin is high. In the production method of the present invention, the total weight ratio of okara and resin in the mixture of okara and resin before heating and melting kneading is 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, It is 98% or more, 99% or more, or 100%. In addition, in this specification, when the "total weight ratio of okara and resin" is used, it may be a value calculated based on the bone dry weight of each okara and resin, or it may be a value calculated based on the weight including water. Although it may be a calculated value, it is typically a value calculated based on bone dry weight. The total weight ratio of okara and resin in the mixture of okara and resin before heating and melt-kneading is preferably 90% by weight or more, more preferably 95% by weight or more, and most preferably 100%.

The total weight ratio of okara and resin in the okara kneading resin of the present invention is 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 98% or more, 99% or more, or 100%. be. The total weight ratio of okara and resin in the okara kneading resin is preferably 90% by weight or more, more preferably 95% by weight or more, and most preferably 100%.

In one embodiment, the okara kneading resin and the manufacturing method thereof of the present invention do not use a sizing agent or a compatibilizer for uniformly blending the okara and the resin. Common sizing agents for uniformly blending bean curd curd and resin include polyvinyl acetate, polyvinyl alcohol, and starch paste. Typical compatibilizing agents for uniformly blending bean curd curd and resin include cellulose esters such as acetylcellulose, diacetylcellulose, triacetylcellulose, nitrocellulose, and cellulose sulfate.

In one embodiment, the okara kneading resin of the present invention may also contain additional components in addition to okara and resin. In typical embodiments, the additional ingredients include fillers for strength reinforcement, flame retardants (triphenyl phosphate, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, etc.), pigments (titanium dioxide, zinc oxide, iron oxide, etc.). etc.). Examples of fillers for strength reinforcement include organic fillers such as cellulose (derived from wood waste, for example), and inorganic fillers such as talc and cement waste. The weight proportion of the additional component in the okara kneading resin of the present invention in the okara kneading resin is 30% by weight or less, and typically 20% by weight or less. In a preferred embodiment, the weight proportion of the additional component in the okara kneading resin of the present invention is 10% by weight or less, more preferably 5% by weight or less, and most preferably 0% by weight ( i.e. not included).

In the okara kneading resin, since the resin solidifies after being melted once, it can be characterized by forming an interconnected network structure. In the okara kneading resin, the okara can maintain its shape before and after kneading, and therefore may exist in the form of particles. In the okara kneading resin, it is preferable that the resin and okara exist uniformly. For example, when a cube of 8 mm ³ is cut out from the okara kneading resin, the weight ratio of okara or resin in any cube is Similarly to the weight proportion of okara or resin in the whole kneaded resin, the difference may be, for example, within 5%, within 3%, or within 1%.

In this specification, in the okara kneading resin, "no peeling" between the okara and the resin means that there are peeling marks where the okara has peeled off from the resin in 80% or more of the surface of the okara kneading resin that can be visually observed. is not observed. In a preferred embodiment, in the okara kneading resin of the present invention, no peeling marks caused by the okara peeling from the resin are observed in 90% or more of the visually observable surface of the okara kneading resin, and in a more preferred embodiment, In this case, no peeling traces of okara peeled from the resin were observed in 95% or more of the surface of the okara kneading resin that could be visually observed. Note that this peeling mark also applies to the okara kneading pellets obtained after cutting the kneaded resin. That is, in the okara kneaded resin pellets of the present invention, the okara and the resin do not separate, and in a preferred embodiment, the okara is separated from the resin in 90% or more of the visually observable surface area of the okara kneaded resin pellets. No peeling marks are observed, and in a more preferred embodiment, no peeling marks are observed when the okara is peeled off from the resin in 95% or more of the surface of the okara kneaded resin pellets that can be visually observed. For example, the peeling marks are caused by the originally existing okara particles falling off from the resin due to peeling, and may be holes formed in the resin or cavities surrounded by the resin. Moreover, peeling can also be characterized by a weak holding power of okara in the kneaded resin. In one embodiment, when the kneaded resin is cut and the newly formed cross section is subjected to horizontal vibration at 100 rpm with an amplitude of 1 cm for 1 minute with the newly formed cross section facing downward, the weight of okara that falls per 1 ^m2 of cross section is is 10 g or less, 1 g or less, 0.1 g or less, or 0.01 g or less, it can also be determined that no peeling has occurred.

Okara kneading resin pellets obtained from the okara kneading resin of the present invention (for example, kneaded resin rods discharged from a 20 mm diameter outlet and cut into pieces at 4 mm intervals by a pelletizer) can be used in a multi-analyte gas adsorption amount measuring device (for example, , Anton Paar, Autosorb-iQ2-XR-VP) at a measurement temperature of 25°C and a relative humidity of 25%, 50%, and 90%. It may have a water vapor adsorption amount of 20 mg or more. Although not intending to be bound by theory, this is due to the fact that the kneaded resin pellets were produced only from okara and resin without using any sizing agent, and that there was a substantial amount of okara. This is thought to be due to this.

(shape and size of resin)
Regarding the shape of the resin to be kneaded with the okara, if the resin is originally in the form of a film or sheet, such as a packaging film or container, it is cut into pieces and submitted to a kneading machine. In this case, the size is preferably 0.1 mm square or more and 10 mm square or less, more preferably 3 mm square or more and 9 mm square or less, and most preferably 6 mm square or more and 8 mm square or less. If the size of the resin is smaller than 0.1 mm square, the scattering due to static electricity will be extremely difficult to operate, and if the size of the resin is larger than 10 mm square, the mixture of resin and okara will be transferred to the hopper shown in Figure 3. 3, there is a concern that the resin will accumulate between the hopper 3 and the screw 4 and the uniformity of the bean curd and the resin will deteriorate.

Further, the thickness is preferably 0.01 mm or more and 10 mm or less, more preferably 0.05 mm or more and 2 mm or less, and most preferably 0.09 mm or more and 0.12 mm or less. If the thickness of the resin is less than 0.01 mm, the scattering due to static electricity will significantly impair operability, and if the thickness of the resin is greater than 10 mm, the mixture of resin and okara will be transferred to the hopper 3 and screw 4 shown in Figure 3. This is because the resin is deposited between the bean curd and the bean curd, resulting in a decrease in the uniformity of the bean curd curd and the resin in the bean curd kneading resin.

When the resin to be kneaded with okara is in the form of fibers, the thickness and number of filaments are not particularly limited, but the fiber length is preferably 1 mm or more and 10 mm or less, more preferably 3 mm or more and 8 mm or less, and most preferably 4 mm or more and 6 mm or less. If the fiber length is less than 1 mm, the scattering due to static electricity will significantly impair operability, and if the fiber length is greater than 10 mm, the mixture of resin and okara will be transferred between the hopper 3 and the screw 4 shown in Fig. 3. This is because the resin accumulates, resulting in a decrease in the uniformity of the okara and resin in the okara kneading resin.

When the shape of the resin to be kneaded with bean curd is granular, the average particle diameter of the granules is preferably 1 mm or more and 10 mm or less, more preferably 3 mm or more and 8 mm or less, and most preferably 4 mm or more and 6 mm or less. If the average particle size is smaller than 1 mm, scattering due to static electricity will significantly impair operability, and if the average particle size is larger than 10 mm, the mixture of resin and okara is poured into the kneader hopper 3 shown in FIG. 3. This is because the okara does not enter the screw 4 at this time, resulting in insufficient mixing with the okara and the uniformity of the okara and resin during kneading.

(size of okara)
The okara generated during the tofu manufacturing process is in the form of powder, but at this point the size of the okara varies. Therefore, it is necessary to grind the okara using a ball mill or the like to control the average particle size of the okara. At this time, the average particle size of the okara to be kneaded with the resin is preferably 10 μm or more and less than 500 μm, more preferably 50 μm or more and less than 250 μm, and most preferably 70 μm or more and less than 100 μm. However, as demonstrated in Examples 1 and 2, if the average particle size of the bean curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd curd lees curd (bean curd curd curd curd) has a particle size of about 200 μm, it is possible to omit the pulverization before kneading. If the average particle size of the bean curd is less than 10 μm, it will easily scatter during mixing, which may reduce operability. If the average particle size of the bean curd is larger than 500 μm, the mixture of resin and okara may This is because the resin accumulates between the hopper 3 and the screw 4 shown in FIG. 3, resulting in a decrease in the uniformity of the okara and resin in the okara kneading resin. In this specification, the term "average particle size" refers to the value obtained by measuring the longest diameter of 20 randomly selected okara particles using a scanning electron microscope, and averaging the measured values. For example, the diameter of okara particles can be measured based on a scale. The size of bean curd curd can be maintained even in the kneaded resin.

(Percentage of water contained in okara)
When the resin and okara are completely dry, static electricity is likely to be generated due to friction during kneading, and the resin and okara are likely to scatter. For this reason, the generation of static electricity is prevented by containing an appropriate amount of water in the bean curd. At this time, the moisture content of the okara is preferably 1% by weight or more and less than 20% by weight, more preferably 5% by weight or more and less than 15% by weight, and most preferably 9% by weight or more and less than 12% by weight. If the moisture content of bean curd is less than 1% by weight, there is a risk that it will scatter during mixing, resulting in large variations in the mixing ratio. This is because there is a concern that the interior of the cylinder 1 will be cooled by the heat of vaporization and the resin will not be sufficiently melted, and particularly in the case of a resin having an ester bond, there is a concern that the molecular weight decrease due to hydrolysis will be significant.

(Percentage of oil contained in okara)
The oil contained in okara improves compatibility with resin and is essential for uniform kneading. For this reason, the oil content contained in bean curd curd lees is preferably 1% by weight or more and 20% by weight or less, more preferably 7% by weight or more and 15% by weight or less, most preferably 11% by weight or more and 13% by weight or less. If the content of oil contained in okara is less than 1% by weight, there is a concern that the kneading with the resin will be uneven and the peeling of okara from the okara kneading resin will become noticeable. This is because if the oil content is more than 20% by weight, there is a concern that the oil will bleed out from the bean curd kneading resin and cause corrosion of mechanical equipment such as a kneader.

(Summary of okara kneading resin pellet production)
The method for producing okara kneaded resin pellets in the present invention includes a step of heating and melting kneading the mixed resin and okara to produce a kneaded product, and a step of cooling and solidifying the kneaded product (hereinafter referred to as the cooling step). include. In a typical embodiment, the method for producing okara kneaded resin pellets according to the present invention includes a step of mixing resin and okara in an arbitrary ratio (hereinafter referred to as a mixing step), and a step of mixing the resin and okara in the mixing step. A process of melt-kneading using a kneading extruder to produce a kneaded product of okara and resin (hereinafter referred to as the kneading process), a process of cooling and solidifying the kneaded product discharged from the kneader (hereinafter referred to as the cooling process) The process further includes a step of cutting the cooled kneaded material into pellets (hereinafter referred to as a cutting step).

(Mixing process)
In the mixing step, resin and okara are mixed at an arbitrary ratio. Typically, the resin and okara are mixed so that the kneading ratio of okara in the above-mentioned okara kneading resin is, for example, 30% by weight or more and 70% by weight or less. The method of mixing is not particularly limited; for example, okara and resin may be put into a container such as a stainless steel pot in any ratio, and then the lid may be closed and the mixture turned upside down manually, or a rotary stirrer may be used. The mixture of resin and okara may be stirred while rotating. At this time, since the okara contains an appropriate amount of water, static electricity is prevented from being generated on the resin surface, making it difficult to scatter.

(Amount of okara and resin added to stirring container)
When mixing okara and resin, it is preferable that the following formula 2 be satisfied between the bulk volume of okara, the bulk volume of resin, and the volume of the stirring container. In addition, V1, V2, and V in Formula 2 represent the bulk volume (L) of okara, the bulk volume (L) of resin, and the volume (L) of the stirrer, respectively.

Regarding the amount of okara and resin charged into the stirring container, (V1+V2)/V is preferably 0.1 or more and 0.8 or less, more preferably 0.3 or more and 0.6 or less, and 0. Most preferably, it is .4 or more and 0.5 or less. If the value of formula 2 is less than 0.1, the loss rate due to adhesion to the inner wall of the stirring container will increase, and if it is greater than 0.8, the okara and resin will not be stirred and mixing will be insufficient. There are concerns that. Actually, compared to the case where (V1+V2)/V exceeds 0.8 and 1.0, when (V1+V2)/V is between 0.1 and 0.8, the obtained okara kneading Both the appearance evaluation (the appearance evaluation based on Table 1 described later) and the amount of water vapor adsorption of the resin pellets were excellent (data not shown).

(Rotation speed of stirrer during rotary stirring)
When mixing okara and resin by rotary stirring, the rotation speed of the stirrer can be any value as long as okara and resin are appropriately stirred, but preferably 1 rpm or more and 30 rpm or less, The speed is more preferably 5 rpm or more and 20 rpm, most preferably 12 rpm or more and 15 rpm or less. If the rotation speed is less than 1 rpm, there is a concern that the okara and resin will not be sufficiently stirred, and if the rotation speed is higher than 30 rpm, there will be no significant difference in the degree of mixing and the technical significance will be diluted. .

(kneading process)
The mixture of okara and resin produced in the mixing step is heated and melted and kneaded. In an exemplary embodiment of the invention, the bean curd and resin mixture is introduced through a kneader hopper 3, which is schematically shown in FIG. A screw 4 having a spiral groove is rotating in the cylinder 1, and the molten resin and bean curd are discharged from the discharge port 5 in a mixed state. At this time, the oil contained in the okara prevents phase separation between the resin and the okara, resulting in uniform kneading. Normally, when kneading food biomass or inorganic fillers that have low compatibility with resin, a compatibilizer is added to improve uniformity, but since the okara used in the present invention contains oil, a compatibilizer is added. Uniform kneading is possible even without this.

(kneading temperature)
In the exemplary embodiment, a heater 6 is installed inside the cylinder 1 of the kneading machine for producing okara kneading resin of the present invention, and the kneading temperature can be arbitrarily controlled by the temperature control section 7. . When kneading bean curd curd and resin, the kneading temperature is preferably 160°C or more and 220°C or less, more preferably 170°C or more and 200°C or less, and most preferably 180°C or more and 190°C or less. In this specification, the term "kneading temperature" refers to the temperature at the hottest point in the cylinder 1. If the kneading temperature is less than 160°C, the resin will not be sufficiently melted, and if the kneading temperature is higher than 220°C, thermal decomposition of the bean curd curd curd curd curd curd lees will be significantly thermally decomposed, and there is a concern that a desirable bean curd kneaded resin may not be obtained. In a preferred embodiment, the kneading step may be performed such that the molecular weight of the resin after kneading increases compared to the molecular weight of the resin before kneading.

(Cylinder material)
The material of the cylinder 1 is not particularly limited either, but it is preferable to use stainless steel or cermet because the cylinder 1 comes into contact with resin and okara containing water, similar to the screw. In addition, it is also preferable to improve corrosion resistance by performing surface treatment such as chrome plating.

(Screw rotation speed)
In the kneading step, the rotation speed of the screw 4 is preferably 50 rpm or more and 120 rpm or less, more preferably 55 rpm or more and 100 rpm or less, and most preferably 60 rpm or more and 80 rpm or less. If the rotation speed of the screw 4 is less than 10 rpm, there is a concern that the resin and okara will receive heat for a long time, making thermal decomposition or hydrolysis more likely to occur, and if it is higher than 100 rpm, the resin may not melt. This is because there is a concern that it will not be enough and that it will not be possible to mix it with the okara. In fact, compared to when the screw rotation speed was 200 rpm, when the screw rotation speed was 50 rpm or more and 120 rpm or less, the obtained okara kneaded resin pellets were superior in both appearance evaluation and water vapor adsorption amount (data (not shown).

(Material of screw)
Although the material of the screw 4 is not particularly limited, it is preferable to use stainless steel or cermet as the material of the screw 4 since okara containing moisture is introduced. In addition, it is also preferable to improve corrosion resistance by performing surface treatment such as chrome plating.

(Automatic exhaust valve)
In a preferred embodiment, the kneading machine used in the heating melting and kneading in the production of the okara kneading resin of the present invention has an automatic kneading machine installed in the cylinder to prevent the internal pressure in the cylinder from increasing due to the evaporation of water contained in the okara. Install exhaust valve 2. At this time, it is preferable that the automatic exhaust valve 2 is set to automatically release water vapor into the atmosphere when the inside of the cylinder becomes 0.05 MPa.G or higher.

(Discharge port diameter)
Although the shape of the discharge port 5 is not particularly limited, a circular shape is most preferable. Moreover, when the shape of the discharge port 5 is circular, the diameter of the discharge port 5 is preferably 1 mm or more and less than 10 mm, more preferably 2 mm or more and 6 mm or less, and most preferably 4 mm or more and less than 5 mm. If the diameter of the discharge port 5 is less than 1 mm, the discharged okara kneaded resin 8 is likely to be cut, and if it is thicker than 10 mm, the okara kneaded resin 8 is easily cut, and the subsequent cooling process or cutting process There is a concern that the operability will deteriorate.

(cooling process)
In the kneading process, rod-shaped okara kneading resin 8 is discharged from the discharge port 5. Immediately after being discharged, the okara kneading resin 8 is transferred to a pelletizer, but a step (cooling step) of cooling and solidifying the okara kneading resin 8 is required before that.

(Cooling method)
The method of cooling the okara kneading resin 8 in the cooling process includes a method of blowing air through the okara kneading resin 8 using a blower or the like (hereinafter referred to as an air cooling method), and a method of impregnating the okara kneading resin 8 in water (hereinafter referred to as an air cooling method). A water cooling method) and a method of contacting a cooling block (hereinafter referred to as a cooling block contact method) are preferable, an air cooling method and a cooling block contact method are more preferable, and an air cooling method is most preferable. This is because not only can the okara kneading resin 8 be cooled by air cooling, but also water is less likely to adhere to the okara.

(cooling distance)
In the cooling process, when cooling the rod-shaped okara kneading resin 8 discharged from the kneader, the distance from the discharge port 5 to the pelletizer 9 (hereinafter referred to as cooling distance) is preferably 1 m or more and 10 m or less, and 2 m or more and 6 m or less. is more preferable, and most preferably 3 m or more and 5 m or less. If the cooling distance is less than 1 m, there is a risk that the okara kneading resin will not be sufficiently cooled, making subsequent cutting difficult.If the cooling distance is longer than 10 m, the okara kneading resin will not be sufficiently cooled with any cooling method. This is because it solidifies sufficiently and becomes of little technical significance. In fact, compared to the case where the cooling distance was 0.3 m, when the cooling distance was 1 m or more, both the appearance evaluation and the amount of water vapor adsorption of the resulting okara kneaded resin pellets were superior (data not shown). ).

(Cooling of okara kneading resin using air cooling method)
FIG. 4 schematically shows the flow of the kneading process, the cooling process using an air cooling system, and the cutting process. When the okara kneading resin 8 is cooled by the air cooling method, the okara kneading resin 8 moves on a feed table 10 installed between the kneader and the pelletizer 9. At this time, air is sent from the blower 11 to the surface of the okara kneading resin 8, and the wind speed to the surface of the okara kneading resin 8 is preferably 1.5 m/s or more and 10 m/s or less, and 3 m/s or more and 7 m/s or less. More preferably, 4 m/s or more and 5 m/s or less is most preferable. If the wind speed on the surface of the bean curd kneading resin 8 is less than 1.5 m/s, the kneaded material will not be sufficiently cooled, making subsequent cutting difficult. This is because there is a concern that the okara kneading resin 8 may be cut.

(Cooling of okara kneading resin using cooling block contact method)
FIG. 5 schematically shows the flow of the kneading process, the cooling process using the cooling block contact method, and the cutting process. When the okara kneading resin 8 is cooled by the cooling block contact method, the temperature of the cooling block 12 is preferably -20°C or more and 10°C or less, more preferably -5°C or more and 5°C or less, and most preferably 0°C or more and 3°C or less. preferable. Even if the temperature of the cooling block 12 is lower than -20°C, there is no difference in the degree of cooling of the kneaded material, and the technical significance becomes weak.If the temperature is higher than 10°C, the cooling of the kneaded material is insufficient, so This is because there is a concern that it will be difficult to cut the paper.

(Cooling of okara kneading resin using water cooling method)
FIG. 6 schematically shows the flow of the kneading process, the water cooling process, and the cutting process. In the case of the water cooling system, the okara kneading resin 8 is cooled by passing through a water tank 13. At this time, the water temperature in the water tank 13 is preferably 0°C or more and 10°C or less, more preferably 2°C or more and 7°C or less, and most preferably 4°C or more and 6°C or less. If the water temperature in the water tank 13 is less than 0°C, the water in the water tank 13 turns into ice and the okara kneading resin 8 cannot be immersed, and if it is higher than 10°C, the okara kneading resin 8 is not sufficiently cooled. This is because there is a concern that subsequent cutting may be difficult. Note that when cooling is performed using a water cooling method, it is necessary to perform a drying process again after the cutting process to remove moisture.

(Cutting process)
The cooled rod-shaped okara kneading resin 8 is cut into arbitrary sizes in a cutting process using a pelletizer 9. At this time, the cutting method is not particularly limited, but it is practically preferable to use a strand cutting method in which the pelletizer uses a rotating blade and a fixed blade. In a preferred embodiment, in the okara kneading resin of the present invention or the okara kneading resin produced by the production method of the present invention, the okara and the resin do not separate even after cutting.

(Cutting interval of okara kneading resin)
When cutting the rod-shaped okara kneading resin 8 sent from the kneading machine with the pelletizer 9, the cutting interval is preferably 1 mm or more and 10 mm or less, more preferably 3 mm or more and 8 mm or less, and most preferably 4 mm or more and 5 mm or less. . This is because if the cutting interval is less than 1 mm, the okara kneaded into the okara kneading resin 8 is likely to peel off, and if it is longer than 10 mm, there is a concern that it is too large to be handled as a moisture-absorbing material.

(Material of pelletizer rotating blade and fixed blade)
FIG. 7 schematically shows the structure inside the pelletizer 9. Inside the pelletizer 9, a rotating blade 14 and a fixed blade 15 are installed. The materials of the rotary blade 14 and fixed blade 15 are not particularly limited, but since okara contains oil, materials with excellent corrosion resistance such as stainless steel or cermet, or surface treatments such as chrome plating are used. This is desirable.

(Collection of okara kneaded resin pellets and subsequent molding)
The okara kneading resin 8 is cut by the rotary blade 14 and fixed blade 15 in the pelletizer 9, and the okara kneading resin pellets 16 are accumulated in a container 17 in which the lower part of the pelletizer is installed. In addition to being used as a hygroscopic material, the okara kneaded resin material pellets thus obtained can be molded into a molded article of any shape by a molding method such as injection molding or extrusion molding. In this specification, an article obtained by processing a kneaded resin or kneaded resin pellets as a material or a part of a material is referred to as a molded article.

Examples for obtaining preferred okara kneaded resin pellets will be shown below and explained in more detail. Note that the examples are for explaining the invention in detail, and are not intended to limit the invention.

[Example 1]
(resin and okara)
The resin used in this example was obtained by cutting a 0.1 mm thick polypropylene film used for tofu packaging into 5 mm square pieces. Regarding the okara generated during the tofu manufacturing process, the okara was placed in a dryer set at 80°C and the moisture content was 5% by weight. Note that the oil content of the okara used in this example was 13% by weight. Furthermore, when the okara was observed using an optical microscope, the average particle size was 202 μm.

(Mixing process)
The resin of this example and okara were mixed so that the okara kneading ratio was 51% by weight, and using a rotary stirrer, the rotation speed was 15 rpm and (V1+V2)/V was 0.6 for 10 minutes. A mixing step was performed.

(kneading process)
A twin-screw kneader (manufactured by Imoto Seisakusho, model IMC-1ADA) was used to knead the resin and okara. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 175°C, 180°C, 180°C, and 170°C, respectively, and the screw rotation speed was 60 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using a fan, and wind at a speed of 4 m/s was blown onto the rod-shaped okara kneading resin. Further, the cooling distance was set to 5 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 4 mm intervals using a pelletizer (manufactured by Imoto Seisakusho, model IMC-1113) to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the five-level evaluation shown in Table 1. Note that an appearance index of 4 or higher was evaluated as "suitable".

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The okara kneaded resin pellets obtained in this example were measured at a measurement temperature of 25°C, a relative humidity of 25%, 50%, and The amount of water vapor adsorption at 90% was measured. In addition, the water vapor adsorption amount at relative humidity of 25%, 50%, and 90% is 3.5 mg, 7.5 mg, and 20 mg, respectively, as reference values, and the water vapor adsorption amount of the okara kneaded resin pellets obtained in this example is If the amount is higher than the standard value, it is judged that the material can be used as a hygroscopic material, and the material is rated as "suitable".

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 5.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per gram of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% were 7.1 mg, 16.7 mg, and 93.3 mg, respectively. Thus, the amount of water vapor adsorption was greater than the standard value.

(comprehensive evaluation)
From the above results, the appearance evaluation and water vapor adsorption amount of the okara kneaded resin pellets obtained in this example both met the standards, so the overall evaluation was appropriate.
[Example 2]

(resin and okara)
The resin used in this example was the same as that used in Example 1. Furthermore, the okara was placed in a dryer set at 80°C and had a moisture content of 1% by weight. Note that the oil content of the okara used in this example was 10% by weight. Furthermore, when the okara was observed using an optical microscope, the average particle size was 198 μm.

(Mixing process)
The resin of this example and okara were placed in a 20 L stainless steel barrel so that the kneading ratio of bean curd was 70% by weight, the lid was closed, and the barrel was manually turned upside down for 10 minutes. At this time, (V1+V2)/V was set to 0.7.

(kneading process)
The same kneader as in Example 1 was used to knead the resin and okara. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 215°C, 220°C, 220°C, and 210°C, respectively, and the screw rotation speed was 120 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using a fan, and wind at a speed of 1.5 m/s was blown onto the rod-shaped okara kneading resin. Moreover, the cooling distance was 1 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 1 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 4.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per 1 g of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% were 8.9 mg, 21.5 mg, and 129.6 mg, respectively. Thus, the amount of water vapor adsorption was higher than the standard value.

(comprehensive evaluation)
From the above results, the appearance evaluation and water vapor adsorption amount of the okara kneaded resin pellets obtained in this example both met the standards, so the overall evaluation was appropriate.
[Example 3]

(resin and okara)
Polybutylene succinate (PTT MCC Biochem, BioPBS FZ71) pellets were used as the resin in this example. Furthermore, the okara used was one that was placed in a dryer set at 80° C. and had a moisture content of 20% by weight. Note that the oil content of the okara used in this example was 9% by weight. Furthermore, the bean curd curd curd curd was ground to an average particle size of 75 μm using a ball mill.

(Mixing process)
The resin of this example and okara were mixed so that the kneading ratio of okara was 30% by weight, and using a rotary stirrer, the rotation speed was 1 rpm, and (V1+V2)/V was 0.8. A mixing step was performed for 1 minute.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 165°C, 170°C, 170°C, and 160°C, respectively, and the screw rotation speed was 50 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. In this example, the rod-shaped bean curd kneading resin was cooled by contacting it with a cooling block cooled to -5°C, and the cooling distance was 10 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 10 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 5.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amount of water vapor adsorbed per gram of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% was 5.2 mg, 10.4 mg, and 40.6 mg, respectively. Thus, the amount of water vapor adsorption was greater than the standard value.

(comprehensive evaluation)
From the above results, both the appearance evaluation and the water vapor adsorption amount met the standards, so the overall evaluation of this example was suitable as a bean curd kneading resin.
[Example 4]

(resin and okara)
The same resin as in Example 1 was used as the resin in this example. Furthermore, the okara used was one that was placed in a dryer set at 80° C. and had a moisture content of 4% by weight. Note that the oil content of the okara used in this example was 14% by weight. Furthermore, the bean curd curd curd curd was ground to an average particle size of 75 μm using a ball mill.

(Mixing process)
The resin of this example and okara were mixed so that the kneading ratio of okara was 20% by weight, and the rotation speed was 30 rpm using a rotary stirrer, and (V1+V2)/V was 0.2. A mixing step was performed for 10 minutes.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 185°C, 190°C, 190°C, and 180°C, respectively, and the screw rotation speed was 55 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using an electric fan, and wind at a speed of 3 m/s was blown onto the rod-shaped bean curd kneading resin. Further, the cooling distance was set to 2 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 3 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 5.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per gram of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% were 1.9 mg, 5.9 mg, and 18.7 mg, respectively. Thus, the amount of water vapor adsorption was greater than the standard value.

(comprehensive evaluation)
From the above results, the appearance evaluation and water vapor adsorption amount of the okara kneaded resin pellets obtained in this example both met the standards, so the overall evaluation was appropriate.
[Example 5]

(resin and okara)
As the resin in this example, a polyethylene film having a thickness of 1 mm was cut into 5 mm squares using a cutting machine. Furthermore, the okara used was one that was placed in a dryer set at 80° C. and had a moisture content of 6% by weight. Note that the oil content of the okara used in this example was 6% by weight. Furthermore, the average particle size of the okara was 200 μm.

(Mixing process)
The resin of this example and okara were mixed so that the kneading ratio of okara was 51% by weight, and the rotation speed was 30 rpm using a rotary stirrer, and (V1+V2)/V was 0.3. A mixing step was performed for 10 minutes.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 155°C, 160°C, 160°C, and 150°C, respectively, and the screw rotation speed was 100 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. In this example, the rod-shaped bean curd kneading resin was cooled by contacting it with a cooling block cooled to 0° C., and the cooling distance was 6 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at intervals of 8 mm using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 5.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per 1 g of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% were 7.8 mg, 17.6 mg, and 95.4 mg, respectively. Thus, the amount of water vapor adsorption was greater than the standard value.

(comprehensive evaluation)
From the above results, the appearance evaluation and water vapor adsorption amount of the okara kneaded resin pellets obtained in this example both met the standards, so the overall evaluation was appropriate.
[Example 6]

(resin and okara)
As the resin in this example, a polyethylene film having a thickness of 1 mm was cut into 5 mm squares using a cutting machine. Furthermore, the okara used was placed in a dryer set at 80°C and had a moisture content of 6% by weight. Note that the oil content of the okara used in this example was 6% by weight. Furthermore, the average particle size of the okara was 200 μm.

(Mixing process)
The resin of this example and okara were mixed so that the kneading ratio of okara was 30% by weight, and the rotation speed was 30 rpm using a rotary stirrer, and (V1+V2)/V was 0.3. A mixing step was performed for 10 minutes.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 195°C, 200°C, 200°C, and 190°C, respectively, and the screw rotation speed was 80 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. In this example, the rod-shaped bean curd kneading resin was cooled by being impregnated in water at a temperature of 5° C., and the cooling distance was set to 4 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 5 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 5.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amount of water vapor adsorbed per 1 g of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% was 4.9 mg, 10.6 mg, and 42.1 mg, respectively. Thus, the amount of water vapor adsorption was greater than the standard value.

(comprehensive evaluation)
From the above results, the appearance evaluation and water vapor adsorption amount of the okara kneaded resin pellets obtained in this example both met the standards, so the overall evaluation was appropriate.
[Example 7]

(resin and okara)
As the resin in this example, a polylactic acid thread (Terramac manufactured by Unitika) having a thickness of 75 denier and 30 filaments was cut into a length of 5 mm. Furthermore, the okara used was placed in a dryer set at 80°C and had a moisture content of 10% by weight. Note that the oil content of the okara used in this example was 13% by weight. Furthermore, the average particle size of the okara was 200 μm.

(Mixing process)
The resin of this example and okara were mixed so that the kneading ratio of okara was 25% by weight, and the rotation speed was 20 rpm using a rotary stirrer, and (V1+V2)/V was 0.7. A mixing step was performed for 10 minutes.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 175°C, 180°C, 180°C, and 170°C, respectively, and the screw rotation speed was 60 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using a fan, and wind at a speed of 4 m/s was blown onto the rod-shaped okara kneading resin. Further, the cooling distance was set to 4 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 4 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this example was evaluated, the evaluation was 5.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per gram of the okara kneaded resin pellets obtained in this example at relative humidity of 25%, 50%, and 90% were 4.4 mg, 9.4 mg, and 27.9 mg, respectively. Thus, the amount of water vapor adsorption was greater than the standard value.

(comprehensive evaluation)
From the above results, the appearance evaluation and water vapor adsorption amount of the okara kneaded resin pellets obtained in this example both met the standards, so the overall evaluation was appropriate.
[Comparative example 1]

(resin and okara)
The resin used in this comparative example was the same as that used in Example 1. Furthermore, since the okara used had just been produced in the tofu manufacturing process, the moisture content was 81% by weight. Note that the oil content of the okara used in this comparative example was 13% by weight. Furthermore, when the okara used in this comparative example was dried and observed under an optical microscope, the average particle size was 201 μm.

(Mixing process)
The resin of this comparative example and okara were mixed so that the kneading ratio of okara was 30% by weight, and using a rotary stirrer, the rotation speed was 12 rpm, and (V1+V2)/V was 0.5. A mixing step was performed for 1 minute.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 175°C, 180°C, 180°C, and 170°C, respectively, and the screw rotation speed was 60 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using a fan, and wind at a speed of 4 m/s was blown onto the rod-shaped okara kneading resin. Moreover, the cooling distance was set to 3 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 5 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this comparative example was evaluated by the same method as described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this comparative example was evaluated, the evaluation was 1.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per 1 g of the okara kneaded resin pellets obtained in this comparative example at relative humidity of 25%, 50%, and 90% were 0.5 mg, 0.9 mg, and 1.2 mg, respectively. Thus, the amount of water vapor adsorption was less than the standard value.

(comprehensive evaluation)
From the above results, both the appearance evaluation and the amount of water vapor adsorption did not meet the standards, so the overall evaluation of this comparative example was unsuitable as an okara kneading resin. This was thought to be because the moisture content of bean curd was too high, resulting in insufficient kneading with the resin. Although the automatic exhaust valve 2 did not operate in this comparative example, it is presumed that the internal pressure tends to increase as the kneading ratio of bean curd curd is increased.
[Comparative example 2]

(resin and okara)
The resin used in this comparative example was the same as that used in Example 1. Furthermore, the okara used was placed in a dryer set at 80°C and had a moisture content of 5% by weight. Furthermore, in this comparative example, the dried okara was immersed in acetone to make the oil content 0% by weight. Furthermore, when the okara used in this comparative example was observed using an optical microscope, the average particle size was 198 μm.

(Mixing process)
The resin of this comparative example and okara were mixed so that the kneading ratio of okara was 51% by weight, and using a rotary stirrer, the rotation speed was 15 rpm, and (V1+V2)/V was set to 0.5. A mixing step was performed for 1 minute.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 175°C, 180°C, 180°C, and 170°C, respectively, and the screw rotation speed was 60 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using a fan, and wind at a speed of 4 m/s was blown onto the rod-shaped okara kneading resin. Moreover, the cooling distance was set to 3 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 5 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this comparative example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this comparative example was evaluated, the evaluation was 1.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per gram of the okara kneaded resin pellets obtained in this comparative example at relative humidity of 25%, 50%, and 90% were 0.3 mg, 1.0 mg, and 1.4 mg, respectively. Thus, the amount of water vapor adsorption was less than the standard value.

(comprehensive evaluation)
From the above results, both the appearance evaluation and the amount of water vapor adsorption did not meet the standards, so the overall evaluation of this comparative example was unsuitable as an okara kneading resin. This was thought to be because the oil content was removed by the degreasing treatment of the bean curd, resulting in a decrease in affinity with the resin.
[Comparative example 3]

(resin and okara)
The resin used in this comparative example was the same as that used in Example 5. Furthermore, the okara used was placed in a dryer set at 80°C and had a moisture content of 10% by weight. Note that the oil content of the okara used in this comparative example was 13% by weight. Furthermore, when the okara used in this comparative example was dried and observed under an optical microscope, the average particle size was 199 μm.

(Mixing process)
The resin and okara of this comparative example were placed in a stainless steel barrel with a capacity of 20 L so that the kneading ratio of bean curd was 30% by weight, the lid was closed, and the barrel was manually turned upside down for 10 minutes. At this time, (V1+V2)/V was set to 0.6.

(kneading process)
The resin and okara were kneaded using the same kneader as in Example 1. In this example, the set temperatures of the heaters 6a, 6b, 6c, and 6n were 295°C, 300°C, 300°C, and 300°C, respectively, and the screw rotation speed was 60 rpm. Note that the diameter of the discharge port was 20 mm.

(cooling process)
The rod-shaped okara kneading resin that came out of the kneader outlet in the kneading process was cooled and solidified in the cooling process. The cooling method in this example was air cooling using a fan, and wind at a speed of 5 m/s was blown onto the rod-shaped okara kneading resin. Further, the cooling distance was set to 4 m.

(Cutting process)
The rod-shaped okara kneading resin solidified in the cooling process was cut into pieces at 4 mm intervals using the same pelletizer as in Example 1 to obtain okara kneading resin pellets.

(Appearance evaluation of okara kneaded resin pellets)
The appearance of the obtained okara kneaded resin pellets was evaluated based on the 5-level evaluation shown in Table 1 in the same manner as in Example 1.

(Evaluation of hygroscopicity of okara kneaded resin pellets)
The hygroscopicity of the okara kneaded resin pellets obtained in this comparative example was evaluated by the method described in Example 1.

(Appearance evaluation results of okara kneaded resin pellets)
When the appearance of the okara kneaded resin pellets obtained in this comparative example was evaluated, the evaluation was 2.

(Water vapor adsorption amount of okara kneaded resin pellets)
The amounts of water vapor adsorbed per 1 g of the okara kneaded resin pellets obtained in this comparative example at relative humidity of 25%, 50%, and 90% were 3.1 mg, 5.3 mg, and 18.1 mg, respectively. Thus, the amount of water vapor adsorption was less than the standard value.

(comprehensive evaluation)
From the above results, both the appearance evaluation and the amount of water vapor adsorption did not meet the standards, so the overall evaluation of this comparative example was unsuitable as an okara kneading resin. This was thought to be because the kneading temperature was high and the okara thermally decomposed, resulting in a decrease in moisture absorption and a decrease in affinity with the resin.

The conditions for producing okara kneaded resin pellets in Examples 1 to 7 and Comparative Examples 1 to 3 are shown in Table 2, and the appearance evaluation, water vapor adsorption amount evaluation, and overall evaluation of the obtained okara kneaded resin pellets are shown in Table 3. Shown all together.

[Example 8]
Okara kneading resin was produced by kneading okara and PBS in the same manner as in Example 3 except that the kneading ratio of okara was changed to 20 wt% instead of 30 wt%. 10 mg of bean curd kneading resin was dissolved in 10 mL of chloroform (manufactured by Kanto Kagaku Co., Ltd.) and filtered through a membrane filter (manufactured by PTFE, 0.50 um), and the molecular weight of PBS was analyzed. The molecular weight distribution measurement results of the sample were calculated in terms of polystyrene.
(Analysis conditions)
Analyzer: Gel permeation chromatography analyzer (DGU-20A3 / LC-20AD / CBM-20A / SIL-20AHT / CTO-20AC / SPD-M20A / RID-10A / FRC-10A, manufactured by Shimadzu Corporation)
Standard material: Shodex STANDARD
(Type: SM-105, peak top molecular weight: 1150, 2970, 6320, 19500, 45100, 139000, 270000, 730000, 1390000, 2380000, manufactured by Showa Denko K.K.)
Sample introduction amount: 20 uL
Mobile phase: chloroform flow rate: 1 mL/min
Column: Shodex GPC K-806M (300 mm x 8.0 mm I.D.)
Column temperature: 40℃
Detector: Refractive index differential detector (RID)
The results are shown below.

From the results shown in Tables 2 and 3 above, it is clear that okara and resin that are not completely degreased and contain a moderate amount of water do not separate from each other, and okara and resin that have hygroscopicity It was confirmed that it was possible to produce kneaded pellets. Therefore, since no compatibilizer or the like is added, a moisture-absorbing material that does not have the disadvantages of thermal decomposition can be obtained. Furthermore, the present invention is very simple and can fully contribute to recycling in a recycling society, and is a highly sustainable method.

1 Kneader cylinder 2 Automatic exhaust valve 3 Hopper 4 Screw 5 Discharge ports 6a, 6b, 6c, 6n Heater
7 Control part 8 Rod-shaped okara kneading resin 9 Pelletizer 10 Feeding stand 11 Air blower 12 Cooling block 13 Water tank 14 Rotating blade 15 Fixed blade 16 Okara kneading resin pellets 17 Container

Claims (13)

A method for producing okara kneading resin, the method comprising:
A step of providing okara containing an oil content of 1% by weight or more and 15% by weight or less and a water content of 3% by weight or more and 20% by weight or less,
heating and melt-kneading the mixture containing the okara and resin at 160° C. or higher and 230° C. or lower to obtain a kneaded product of the okara and resin;
a step of releasing water vapor generated during the heating melt-kneading to the outside of the cylinder that performs the heating melt-kneading;
cooling the kneaded material;
, the total weight proportion of the okara and the resin in the mixture is 70% by weight or more, and produced without using a sizing agent or a compatibilizer for uniformly blending the okara and the resin. The sizing agent is glyoxal, polyvinyl acetate, polyvinyl alcohol, or starch paste, and the compatibilizing agent is cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose nitro, or cellulose sulfate. can be,
The resin has as a main component one or more selected from polypropylene and polyethylene,
A method in which the weight proportion of okara in the okara kneading resin is 30% by weight or more and 70% by weight or less . The method according to claim 1, wherein the total weight proportion of the okara and the resin in the mixture is 80% by weight or more. The method according to claim 1, wherein the total weight proportion of the okara and the resin in the mixture is 90% by weight or more. In the step of releasing water vapor, the internal pressure of the cylinder is 0.05 MPa. The method according to any one of claims 1 to 3 , characterized in that the method is carried out in such a way that it does not exceed G. The method according to any one of claims 1 to 4 , wherein the okara kneading resin is one in which the okara and the resin do not separate. The method according to any one of claims 1 to 5 , further comprising the step of cutting the kneaded material into lengths of 1 mm or more and 10 mm or less to form pellets. The mixture further includes a step of mixing a filler, a flame retardant, and/or a pigment, wherein the filler includes cellulose and talc, and the flame retardant includes triphenyl phosphate, aluminum hydroxide, magnesium hydroxide, and water. 7. A method according to any one of claims 1 to 6, comprising calcium oxide, and wherein the pigment comprises titanium dioxide, zinc oxide, and iron oxide. A method for manufacturing a resin molded product, the method comprising:
A step of providing okara kneading resin by the method for producing okara kneading resin according to any one of claims 1 to 7 ;
Processing the okara kneading resin to obtain a resin molded product;
A method that encompasses. Okara kneading resin is obtained by heat-melting and kneading okara and resin at a temperature of 160° C. or more and 230° C. or less , wherein the total weight proportion of the okara and the resin in the okara kneading resin is 80% by weight or more. ,
The okara contains an oil content of 1% by weight or more and 15% by weight or less, and a water content of 3% by weight or more and 20% by weight or less,
The kneaded resin is manufactured in such a way that the water vapor generated during the heated melt-kneading is released to the outside of the cylinder that performs the heated melt-kneaded,
The kneading resin is characterized in that it is produced without using a sizing agent or a compatibilizing agent for uniformly blending the okara and the resin, and the sizing agent includes glyoxal, polyvinyl acetate, polyvinyl alcohol, or a starch paste, and the compatibilizing agent is cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose nitro, or cellulose sulfate,
The resin has as a main component one or more selected from polypropylene and polyethylene,
Okara kneading resin, wherein the weight proportion of okara in the okara kneading resin is 30% by weight or more and 70% by weight or less . The okara kneading resin according to claim 9 , wherein the total weight proportion of the okara and the resin in the kneading resin is 90% by weight or more. The okara kneading resin according to claim 9 or 10 , wherein the okara and the resin do not separate. Okara kneading resin produced by the method for producing okara kneading resin according to any one of claims 1 to 6 . When measured at a measurement temperature of 25° C. and a relative humidity of 25%, 50% and 90%, the adsorption amount of water vapor is 3.5 mg, 7.5 mg and 20 mg or more per 1 g of the okara kneading resin, respectively. 12. Okara kneading resin according to any one of Item 11 .

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