JP2003191264A - Method for manufacturing biodegradable molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for which a biodegradable molded article having sufficient strength is simply manufactured even in a case of having a complicated shape, and having sufficient water resistance and extremely good biodegradability is secured. <P>SOLUTION: A molding raw material 14, a cover film 12 and a mold 20a comprising a projected mold piece 21a and a recessed mold piece 22a are used to arrange the molding raw material 14, and the cover film 12 between the projected mold piece 21a and the recessed mold piece 22a and at least one of the projected mold piece 21a and the recessed mold piece 22a is moved in the fitting direction of both mold pieces while heated to deform the central part of the cover film 12. By this constitution, the molding raw material 14 is subjected to steam foam molding, and the cover film 12 is simultaneously softened to be bonded to the surface of a biodegradable foam molded article under pressure. Further, at least during the deformation of the cover film 12, the relative moving speed of the projected mold piece 21a to the fixing plane of the cover film is held to 8-12 mm/s. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a foamed molded product (biodegradable molded product) which is mainly composed of starch and has biodegradability.
In particular, the present invention relates to a method for producing a biodegradable molded article that can be suitably used as a disposable foamed molded article that is discarded after use, such as a food container, molding cushioning material, guess, packaging tray, etc. It is about. Further, the present invention is a method for producing a biodegradable molded article suitable for producing a biodegradable molded article having a deep drawing shape such as a bowl shape or a cup shape using a substantially flat coating film. It is about.

[0002]

2. Description of the Related Art As a method for disposing molded articles, a technology for disposing molded articles by biodegradation utilizing microorganisms has been developed and is in the limelight. In particular, in the above-mentioned biodegradation disposal technique, a technique utilizing a natural polymer such as starch or protein has been drawing attention from the viewpoint of practicality. This means that the above-mentioned various biodegradable plastics have the same excellent quality as the conventional plastics (non-degradable or hardly degradable), but in reality, the biodegradation rate is slow. This is because it has problems.

For example, if the thickness (thickness) of a molded product formed of biodegradable plastic is large, it takes a very long time to completely decompose the molded product. The volume cannot be increased. In addition, when the molded product made of the biodegradable plastic is used as disposable tableware or the like, composting with food residue is the most environmentally friendly treatment method. However, the decomposition rate of the biodegradable plastic is much slower than that of food residues, and thus it is difficult to perform composting. Moreover, in general, when the molded product has thickness and strength, it is difficult to perform crushing treatment, and therefore it is difficult to crush to improve the decomposition rate of the biodegradable plastic. Composting is virtually impossible.

On the other hand, starch, protein and the like have good biodegradability and can be decomposed very easily even if the volume is increased. Since it is possible to secure resources, it is mostly used as a foamed molded product, and therefore, there is an advantage that a molded product having an appropriate thickness and heat insulating property can be obtained, and it is particularly noted. .

As a disposal technique by biodegradation using the above-mentioned starch or protein, for example, Japanese Patent Laid-Open No.
320401, JP 7-224173 A, JP 7-10148 A, JP 2000-A.
Various techniques such as 142783 and JP-A-7-97545 can be cited.

[0006] First, since the natural raw material of starch is used as the main raw material in the above-mentioned techniques, it is possible to exhibit better degradability than biodegradable plastics, and it is possible to obtain a molded shape that is superior to paper / pulp. Although it has the advantage of being highly versatile, it has problems of poor water and humidity resistance, limited applications, and need for moisture-proof storage.

[0007] Next, according to the techniques (1) and (2), a molded product is molded using starch or various polysaccharides similar thereto as a main raw material, and in order to improve water resistance, a natural resin (Danmar resin) is formed on the surface of the molded product. Or shellac resin) to form a water resistant coating.

However, in a molded product obtained by molding starch as the main raw material (including a foamed molded product), the surface is not perfectly smooth and fine irregularities are formed. Fine pinholes are likely to occur at positions corresponding to the uneven portions of the water resistant coating. Therefore, it is difficult to impart complete water resistance even if some water repellency can be expected. In particular, when moisture resistance is required, moisture is likely to be absorbed from the pinholes of the water resistant coating, which causes problems such as easy deformation of the molded product.

In addition, the above-mentioned dammar resin or shellac resin must be dissolved in an organic solvent such as alcohol for coating. Therefore, when removing the organic solvent after the coating process, a large-scale device is required to prevent these organic solvents from diffusing into the air and contaminating the atmosphere or the surrounding environment. Invite.

[0010] Next, in the above technique, as in the above technique, a raw material obtained by dissolving an aliphatic polyester in a halogenated hydrocarbon is applied to the surface of a biodegradable material having poor water resistance, such as starch. A degradable coating agent is applied. In this technique, since a dip method (immersion coating method) is used as a specific coating method, it is possible to form an appropriate water resistant coating even on a molded article having a complicated shape.

However, in this technique, it is necessary to remove the halogenated hydrocarbon used for dissolving the coating agent, and similarly to the technique described above, a device for preventing the diffusion of the halogenated hydrocarbon is required. And other problems. Moreover, many of the halogenated hydrocarbons are not suitable for the human body and the environment, and since the halogenated hydrocarbons specifically mentioned in the technology are freon-based, they should not be dispersed in the air as much as possible. I won't. As a result, there is a problem in that a large-scale airtight chamber and a recovery device are required as the above device.

In addition to the above-mentioned techniques, there is a method of preparing wax or hydrophobic protein as a coating liquid and then coating it on the surface of a molded article. Generally, a water resistant coating is sufficiently uniform over the entire surface of the molded article. And it is difficult to apply completely. It is relatively easy to apply if it is a flat molded product such as a flat plate, but as described above, the molded product mainly composed of starch tends to have irregularities on its surface, which hinders the formation of a uniform film. In the case of a molded product having a substantially circular cross section such as a cup shape or a bowl shape, it is necessary to rotate the molded product or the coating device, which further increases the difficulty of coating.

Further, even if the coating liquid can be applied sufficiently uniformly by using, for example, a dipping method, the coating liquid after coating solidifies and flows down until it is formed into a coating film, and unevenness in the coating film easily occurs. There is also a problem.

Further, the above wax has a problem that it has poor heat resistance because of its relatively low melting point. Furthermore, although the above hydrophobic protein has relatively good heat resistance and does not require the use of an organic solvent, since an aqueous solvent is often used, the molded product absorbs moisture during the coating process to soften or deform. There is also the problem of causing it.

Therefore, a technique of laminating a water resistant coating on the surface of the molded article instead of applying the water resistant coating has been conventionally proposed. Specifically, for example, JP-A-11-171238 and JP-A-5-27873.
Techniques such as JP-A No. 8 and JP-A-5-294332 are cited.

In the above technique, the container obtained by the pulp molding method rather than molding starch is covered with a non-water-permeable or non-absorbable protective layer. This technology has the advantage that the conventional plastic coating technology for paper containers can be applied almost as is,
Since the pulp mold is mainly composed of fibers, the biodegradation rate is slow, it cannot be discarded together with food residues, it is difficult to add thickness to the container, and it does not lend itself to deep-drawing molding. There is a problem that it is not suitable for the production of various molded products.

On the other hand, in the above techniques and, the surface of a biodegradable container made of natural polysaccharides or proteins, or those chemically modified within the biodegradable range is coated with a thin film of biodegradable plastic, Manufactures biodegradable containers.

In this technique, the biodegradable plastic is used as a thin water resistant coating, while the container body is molded as a container having a sufficient thickness with natural polysaccharides, proteins, etc. While exhibiting
It can also exhibit sufficient biodegradability. therefore,
It is a particularly promising technique as a biodegradable disposal technique using starch or protein.

[0019]

However, in the above technique, the structure of the biodegradable container body is simply covered with the biodegradable plastic thin film, and the specific structure of the biodegradable container is described below. Is hardly mentioned.

For example, when the main body of the biodegradable container is mainly composed of polysaccharides or proteins, the strength thereof becomes a problem, but the technology of (1) does not explain the strength at all. Further, there is no description at all about how to specifically coat the biodegradable plastic thin film, for example, whether it is formed by a coating method or whether a coating film is previously formed and attached.

Further, in the above technique, the coating state of the biodegradable plastic thin film on the body of the biodegradable container is not specified at all. The biodegradable plastic thin film is coated in order to improve the water resistance of the biodegradable container body containing a polysaccharide or a protein as a main component, but in the above technique, it is simply coated. It is mentioned, but nothing about what the coating looks like.

No matter how many times the biodegradable container is used for disposable purposes, stability and durability as a one-way container are required. If the biodegradable plastic thin film easily peels off from the body of the biodegradable container, it is durable. It cannot be said that there is a nature. Therefore, the coating state on the container body is an important condition, but the above technique does not consider this point at all.

Moreover, as described above, since biodegradable plastics have a slow biodegradation rate, it is difficult to use them as a thick molded article. However, the biodegradable rate is not limited to the thickness of the molded article. It also largely depends on the total amount contained in the molded product. Here, in the above technology, it is only stated that foaming the biodegradable container body improves the biodegradability, and the relationship between the degree of foaming and the biodegradability and the relationship between biodegradable plastic and biodegradable plastics. No mention is made of the balance of biodegradation with the main body of the sex container, and therefore, the biodegradation of one whole container cannot be favorably advanced.

On the other hand, the above technique is supposed to correspond to one of the biodegradable container manufacturing methods disclosed above. In this technique, a thermoplastic is dissolved in a solvent to After coating on the surface of the biodegradable container body and drying it to volatilize the solvent, another coating thin film made of thermoplastic is laminated and thermocompression bonded. That is, it is disclosed that a thermoplastic resin is used as an adhesive in order to stably attach a coating thin film (corresponding to a biodegradable plastic thin film).

Here, as described in the above-mentioned techniques, when the thermoplastic resin is used by being dissolved in a solvent, there arises a problem that a device for preventing the diffusion of the solvent is required. Moreover, chloroform is used as a solvent in a specific example of this technique, and this should not be scattered into the atmosphere as much as possible. There is also a problem that a device is required.

Further, in the above manufacturing method, a sheet is first formed from a polysaccharide or protein, and then the sheet is press-molded by a mold to obtain a biodegradable container body. Therefore, for example, deep-drawn containers such as cups, food trays with partitions and packaging trays with uneven thickness, and molded articles with complex shapes such as cushioning materials for packaging. The problem is that you cannot do it.

The present invention has been made in view of the above problems, and an object thereof is to have sufficient strength even with a complicated shape, sufficient water resistance, and a very good raw material. It is an object of the present invention to provide a method for producing a biodegradable molded article, which can easily produce a biodegradable molded article having degradability.

[0028]

In order to solve the above-mentioned problems, the method for producing a biodegradable molded article according to the present invention is "a slurry obtained by mixing starch and a derivative thereof as a main component with water. -Like or dough-shaped forming raw material and a biodegradable plastic as a main component, and using a hydrophobic coating film, the above-mentioned forming raw material and the coating film are heat-molded in a molding die to obtain biodegradability. At the same time that the foamed molded product is subjected to steam foaming molding, the covering film is softened and pressure-bonded to the surface of the biodegradable foamed molded product. "

Therefore, the method for producing a biodegradable molded article of the present invention has the following advantages. That is, first, according to the above method, starch as a main component is mixed with water to prepare a slurry-like or dough-like forming raw material,
By steam-foam molding using this molding raw material, it is possible to easily mold even a very complicated shape, and the resulting biodegradable foam molded article will have a certain water content, which means that conventional starch molding is possible. It can exhibit superior strength as compared to a product.

Further, according to the above method, the coating film is mainly composed of biodegradable plastic having properties close to those of general plastics, and at least has hydrophobic property. A degradable molded product can be produced.

Further, according to the above-mentioned method, since the steam foam molding of the molding raw material and the pressure bonding of the covering film are carried out at the same time, it becomes possible to manufacture the biodegradable molded product in a smaller number of steps, and the biodegradable molding is possible. The product can be manufactured by a simple method.

Further, according to the above method, the coating film is pressure-bonded to the surface of the biodegradable foamed molded article by heat molding in the molding die, so that the coated film is substantially adhered to the surface of the biodegradable foamed molded article. It is possible to obtain a biodegradable molded product in a state, and it is difficult for the coating film to peel from the surface of the biodegradable foamed molded product. Therefore, the water resistance of the biodegradable molded product can be more reliably ensured.

By the way, the present inventors have already made the starch or its derivative as a main component, and a slurry-like or dough-like forming raw material obtained by mixing this with water, and a biodegradable plastic as a main component. , A coating film having at least a hydrophobic property is used to heat the above-mentioned forming raw material and the coating film in a molding die to form a biodegradable foamed molded product of a predetermined shape by steam foam molding, and at the same time, form a coating film. The invention of a method for producing a biodegradable molded article including a simultaneous-pasting step in which the coating film is finally attached to the surface of the biodegradable foamed molded article by heating, softening and pressure bonding has been applied for. (International application PCT / JP
01/07903).

The above-mentioned prior invention is an excellent invention capable of producing a biodegradable molded article excellent in biodegradability and water resistance, reducing the number of production steps, and shortening the production time.

However, in the above-mentioned prior invention, when a deep-drawing biodegradable molded article such as a bowl type container or a cup type container is manufactured as the biodegradable molded article,
The coating film is preliminarily formed into a shape substantially the same as the outer shape of the biodegradable molded article, or the coating film is
As shown in the development view, the film was divided into a plurality of film pieces so that the overall shape of the biodegradable molded product was approximately the same. Therefore, at least two steps were required to produce a deep-drawn biodegradable molded product from the coated film.

Another object of the present invention is to provide a method for producing a biodegradable molded product which can produce a deep-drawn biodegradable molded product such as a bowl type container and a cup type container in a smaller number of steps. It is in.

The method for producing a biodegradable molded article according to the present invention has the above-mentioned basic constitutional requirements, and in order to achieve the above-mentioned object, "a coating film is formed in a deep drawing mold together with the molding raw material. By arranging them in a substantially plane shape and performing the above-mentioned thermoforming, a deep-drawn biodegradable molded article is manufactured. "

According to the above method, since the covering film is arranged in a substantially flat shape when the covering film is pressure-bonded, a commercially available substantially flat or roll-shaped film can be used as it is as the covering film. therefore,
The step of preforming the coating film can be omitted, and the manufacturing process can be greatly simplified.

Further, according to the above method, since the covering film is arranged in a substantially plane shape, the covering film can be easily supplied, and the covering film is conveyed by rollers, clamps or the like and continuously supplied. Is possible. Therefore, it becomes possible to continuously produce a deep-drawn biodegradable molded product.

In the specification of the present application, the "deep-drawing shaped article" is a concave shape having a depth of 30 mm or more, and (1) the center line (the center of the bottom surface and the center of the opening are At least one of the inclination angles of the side surfaces with respect to the connecting straight line) is 30 ° or less, and (2) the aspect ratio (longitudinal dimension / lateral dimension) is 0.3 or more. The vertical dimension is the height direction (center line direction).
Refers to the maximum external dimension, and the lateral dimension refers to the maximum external dimension in the direction (radial direction) orthogonal to the height direction.

In the case of a food container, the deep-drawing shape is generally “cup”, “cup”, “bowl”, “donburi”,
It corresponds to the shape called "bowl". On the other hand, a concave shape that is not a deep-drawing shape (hereinafter referred to as a shallow-drawing shape) corresponds to a shape called “tray”, “flat plate”, “round plate”, “square plate”, etc. in the case of food containers. To do.

In the above-mentioned manufacturing method, the coating film having a substantially flat shape is directly preliminarily formed into a deep-drawing shape by heating and pressing the coating film having a substantially flat surface in a molding die without preforming the coating film having a substantially flat shape. It is designed to be molded. Therefore, compared with the case of forming a substantially flat cover film into a shallow drawing shape such as a dish shape without preforming, or the case of forming the cover film into a deep drawing shape after preforming, the cover film is pressed at the time of crimping. Must be stretched significantly.
However, depending on the type of biodegradable plastic, when a biaxially stretched film having excellent heat resistance and gas barrier properties is used as the covering film, it tends to be unable to be significantly stretched during molding. Therefore, unless the heating conditions in the mold are optimized so that the covering film is sufficiently stretched, defects such as tears, cracks, and pinholes may occur in the covering film when the covering film is stretched.

Still another object of the present invention is to more surely avoid the occurrence of defects in the coating film, particularly when a deep-drawing biodegradable molded product is produced using a substantially flat coating film. Another object of the present invention is to provide a method for producing a biodegradable molded article, which can ensure the water resistance of the biodegradable molded article more reliably.

Another method for producing a biodegradable molded article according to the present invention has the above-mentioned basic constitutional requirements and, in order to achieve the above-mentioned object, "using a mold comprising a pair of a convex mold and a concave mold, Before the heat molding, the molding raw material and the covering film are arranged between the convex mold and the concave mold, and at the time of the heat molding, the covering film is moved by moving at least one of the convex mold and the concave mold in the direction in which they are fitted. Of the convex type relative to the plane formed by connecting the surfaces of the non-deformed portions of the outer periphery of the coating film while the central portion of the convex portion is deformed and at least the deformation of the coating film is 8 mm / s to Keep within 12 mm / s. "
It has the feature point.

According to the above method, since the speed at which the coating film is stretched by the convex mold is kept substantially constant and at the optimum speed, a deep-drawing-shaped raw material is produced by using a substantially flat coating film. When producing a degradable molded product, it is possible to avoid tears, cracks, and pinholes in the coating film. Therefore, the biodegradable foamed molded article can be more surely covered with the coating film, so that the water resistance of the biodegradable molded article can be more reliably ensured.

In the above method, it is preferable that the convex type and the concave type are linearly brought close to each other at least during the deformation of the covering film.

According to the above method, for example, the pressure applied to the coating film by the convex mold is more uniform as compared with the case where one side of the convex mold is connected to one side of the concave mold by a hinge and the convex mold is rotated. Becomes Therefore, in particular, when producing a biodegradable molded product having a very deep drawing, or when producing a biodegradable molded product having a more complicated shape, it is possible to stretch the coating film uniformly, Uniform wall thickness.
Therefore, the effect of the coating film, that is, the water resistance of the biodegradable molded product is further improved.

In the above method, it is preferable to move both the convex mold and the concave mold in a direction in which they approach each other at least until the coating film starts to deform.

According to the above method, at least until the coating film starts to deform, both the convex mold and the concave mold are moved toward each other, so that the time required for fitting the convex mold into the concave mold (fitting time). Can be shortened, and as a result, the manufacturing time can be shortened.

Further, another method for producing a biodegradable molded article according to the present invention has the above-mentioned basic constitutional requirements, and in order to achieve still another object of the present invention, "the temperature of the molding die is The heating is performed so as to be equal to or higher than the softening point of the film and lower than the melting point of the coating film by 10 ° C. or more. ”

According to the above method, the temperature of the molding die is lower than the melting point of the coating film by 10 ° C. or more, so that the coating film is softened without melting and molded into a shape corresponding to the molding die. This makes it possible to avoid pinholes in the coating film, especially when a deep-drawing biodegradable molded product is produced using the coating film having a substantially flat surface. Therefore, the biodegradable foamed molded article can be more surely covered with the coating film, so that the water resistance of the biodegradable molded article can be more reliably ensured.

In the above method, it is preferable to heat the mold so that the temperature of the mold is 130 ° C. or higher.

According to the above-mentioned method, since the molding raw material can be sufficiently heated and steam-foam molded, the steam-foam molding time can be shortened, and the steam-foaming condition becomes good, resulting in a uniform and dense structure. A biodegradable foamed molded product having Therefore, the production time can be shortened and the properties such as strength of the resulting biodegradable molded product can be improved.

In the above method, it is more preferable to heat the mold so that the temperature of the mold is 150 ° C. or higher.

According to the above method, the molding raw material can be heated more sufficiently to be steam-foamed and molded.
While further shortening the molding time of steam foam molding,
The steam foaming conditions are further improved, and a biodegradable foamed molded product having a more uniform and dense structure can be obtained. Therefore, the production time can be further shortened and the properties such as strength of the obtained biodegradable molded article can be improved.

In each of the above methods, it is preferable to dispose a slip agent (lubricant) on the surface of the mold contacting the coating film before the heat molding.

According to the above method, contact friction between the surface of the coating film and the surface of the molding die can be reduced. Therefore, when the coating film is stretched by the molding die, the coating film is ruptured or cracked due to the friction with the molding die. It is possible to avoid such damage.

In the present specification, the term "slip agent" means contact friction between the surface of the coated film after molding and the surface of the mold so that the obtained biodegradable molded product is easily separated from the mold. Is used to prevent the coating film from sticking to the mold and is not limited to so-called "lubricants".

The slip agent is preferably a fluororesin layer formed on the surface of the mold.

In the above method, when a liquid slip agent (such as a lubricant or oil) is applied to the surface of the mold contacting the coating film, or when a slip agent in the form of fine particles (inorganic particles) is applied to the surface of the mold contacting the coating film. And the like) have the following advantages as compared with the case where they are attached.

That is, when a liquid slip agent is applied or a fine particle slip agent is adhered, the slip agent peels off from the surface of the mold during molding, so it is necessary to apply the slip agent each time molding is performed. There is. On the other hand, in the above method, since the fluororesin layer is formed on the surface of the molding die to serve as the slip agent, the slip agent does not peel off from the surface of the molding die during molding and can be used for a long time. Therefore, the labor of disposing the slip agent on the surface of the molding die can be reduced.

When a liquid slip agent is applied or a fine particle slip agent is adhered, the slip agent adheres to the surface of the biodegradable molded product during molding, so that biodegradable molding is performed after molding. It is necessary to remove the slip agent from the object surface. On the other hand, in the above method, the slip agent does not adhere to the surface of the biodegradable molded article during molding and the surface of the biodegradable molded article is not contaminated. It can be omitted.

[0063]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. 1 to 8.
The present invention is not limited to this.

First, the biodegradable molded article produced by the production method of the present invention will be described.

The biodegradable molded article produced by the production method of the present invention includes a biodegradable foamed article having a predetermined shape obtained by steam foam molding of a molding raw material described below, and a coating film attached to the surface thereof. The coated film is a biodegradable molded article containing, and having at least hydrophobicity, the biodegradable plastic being the main component.

In the above biodegradable molded product, the volume ratio of the air phase contained in the biodegradable foamed product is preferably more than 30% by volume based on the total volume of the biodegradable molded product. As a result, the surface area of the biodegradable foamed article is increased, and microorganisms that biodegrade the biodegradable foamed article are easily incorporated. Therefore, the biodegradable foamed molded article is easily biodegraded, and as a result, the biodegradability of the biodegradable molded article can be further improved.

In the following description, the above-mentioned biodegradable foamed molded product will be appropriately abbreviated as "foamed molded product". The term "slurry state" refers to a state in which sufficient fluidity is obtained at least in the state where water is added to starch. Therefore,
Starch does not need to be dissolved in water, but may be in a state close to a suspension. On the other hand, the dough-like state is a state in which the fluidity is lower than that of the slurry-like state, and is a state close to a semi-solid state.

The production method of the present invention is a method for producing a deep-drawn biodegradable molded article, or a method suitable for producing a deep-drawn biodegradable molded article.

As an example of the deep-drawn biodegradable molded article, a bowl-shaped container (a bowl-shaped container) is specifically mentioned. As shown in FIG. 2 (a), the bowl type container 10 a includes a container body 11 a which is the above-mentioned biodegradable foamed molded product, and a covering film which is directly and substantially adhered so as to cover the surface thereof. 12 and. As described later, the surface of the container body 11a does not need to be entirely covered with the coating film 12,
It may be partially covered.

Another example of the deep-drawn biodegradable molded article is a cup-shaped container (cup-shaped container).
As shown in FIG. 3 (a), the cup-shaped container 10 b also has a structure including a container body 11 b which is the biodegradable foamed molded product and a coating film 12. 3A and 3B, the upper diagram is a vertical sectional view of the cup-shaped container 10b, and the lower diagram is a plan view corresponding to the upper diagram (the cup-shaped container 10b is viewed from above). Figure
Is.

The method for producing a biodegradable molded article according to the present invention comprises a raw material for molding in the form of a slurry or a dough obtained by mixing starch or a derivative thereof as a main component with water, and a biodegradable plastic. Using a coating film having hydrophobicity as a main component, the coating film is placed in a deep-drawing mold together with the forming raw material in a substantially planar shape, and the forming raw material and the coating film are formed into a deep-drawing shape. A method for producing a deep-drawing biodegradable molded article, in which the biodegradable foamed article is steam foam-molded by heating in a mold, and at the same time, the coating film is softened and pressure-bonded to the surface of the biodegradable foamed article. Is.

Since the method for producing a biodegradable molded article according to the present invention is a method of directly attaching the covering film to the foamed molded article at the same time as the steam foam molding of the raw material for molding, a predetermined shape is formed from the raw material for molding. When compared with the method of sticking the covering film with an adhesive after steam-foaming the foamed molded product (hereinafter referred to as the post-sticking method), it has the following advantages.

In the biodegradable molded product obtained by this method, as shown in FIGS. 1 (a) and 2 (a), the covering film 12 is directly formed on the surface of the foamed molded product (the container main bodies 11a and 11b). It will be configured. First, the first advantage is that the number of steps can be reduced. That is, according to this method, the covering film 12 can be attached in a minimum of one step, so that the number of steps can be reduced as compared with the above-mentioned post-adhesion method, which requires at least two steps. Further, since the attachment can be performed in one step, the time required for manufacturing can be shortened.
Therefore, the production efficiency of the biodegradable molded product according to the present invention can be improved.

The second advantage is that it is not necessary to use a pasting type. That is, since the foamed molded product (container main body 11a, etc.) is molded by the molding die (mold 20a, etc.), the covering film 12 is also adhered at the same time. No mold needed. Therefore, it is possible to reduce the cost required for the manufacturing facility and to eliminate the need for the bonding facility including the above-mentioned bonding die, so that the space for the manufacturing facility can be saved.

The third advantage is that it is not necessary to use an adhesive. Therefore, the raw material cost for the adhesive can be suppressed, and the content ratio of starch in the biodegradable molded product obtained by not using the adhesive can be increased to further improve the biodegradability.

As a fourth advantage, in this method, the covering film 12 is formed directly on the surface of the foamed molded product (container main bodies 11a and 11b), and the covering film 12 is attached in close contact with the foamed molded product. The point that the attached state of the covering film 12 becomes stable is mentioned.

In the production method of the present invention, at least at a temperature not lower than the softening point (softening start temperature) of the biodegradable plastic which is the main component of the covering film 12 and lower than the melting point, the covering film is formed at the same time as the steam foam molding of the molding raw material. 12 is pasted. Therefore, the coating film 12 faces the foam molded article in the foam molding process in a state of being heated and pressed, and is subjected to the pressure of the mold from the outside in the softened state, and the foam molding process is performed from the inside. While being subjected to the pressure of a foam-molded product, the foam-molded product comes into close contact with the foam-molded product. As a result, the covering film 12 is attached to the surface of the foamed molded product in such a manner as to be fused.

In this way, in the cross section of the biodegradable molded product obtained, the layer of the covering film 12 and the foamed molded product 1 are
The boundary surface with the surface of No. 1 does not become a smooth surface as in the case of a simple sticking method (post sticking method), but becomes an irregular surface having irregularities, for example, and the covering film 12 is a foam molded article. It is in a state of being sufficiently adhered to 11. As a result, the adhered state of the covering film 12 becomes extremely strong, and the stability of the adhered state is at the same level as when the adhesive layer is provided. Therefore, the water resistance and gas barrier property of the obtained biodegradable molded article can be further improved.

The boundary surface between the layer of the covering film 12 and the surface of the foamed molded product 11 may vary depending on the components of the covering film 12, components contained in the foamed molded product 11 and manufacturing conditions.
It can be a boundary surface of various shapes.

When the above four advantages are combined, the biodegradable molded product can be produced by the production method according to the present invention more efficiently and at lower cost than the post-pasting method. The molded product can be provided at a lower price. Therefore, the biodegradable molded product according to the present invention can be easily used for a disposable application.

Next, the molding raw material used in the present invention will be described. The molding raw material used in the present invention contains starch or its derivative as a main component, and is obtained by mixing this with water.

The starch used as the main raw material of the above-mentioned molding raw material is not particularly limited. For example, potatoes, corn, tapioca, rice,
Starch which can be easily obtained from agricultural products that are produced worldwide as the main grains such as wheat and sweet potato can be preferably used. The above-mentioned starch may be produced from a specific agricultural product, or may be produced by mixing a plurality of agricultural products.

Further, the above-mentioned starch derivative refers to starch modified within the range of not inhibiting biodegradability, and specific examples thereof include pregelatinized starch, crosslinked starch and modified starch. Furthermore, it is also possible to use a mixture in which the unmodified starch and the starch derivative are mixed. Therefore, in a broad sense, the starch in the present invention includes starch which is not modified at all (starch in a narrow sense), derivatives of the above starch, and a mixture thereof. In the following description, unless otherwise specified, “starch” means broadly defined starch.

The content of starch contained in the above molding raw material is 100 based on the total amount of main solids of the molding raw material.
When the weight percentage is set, it is preferably in the range of 50 wt% or more and 100 wt% or less. Further, when the total amount of the forming raw material including water is 100% by weight, it is preferably in the range of 20% by weight or more and 60% by weight or less. Within this range, the biodegradable molded product according to the present invention can be considered to have starch as its main component, and can exhibit good biodegradability. In addition,
In the present specification, the starch as the main raw material and the bulking agent which is a bulking additive among the additives are collectively referred to as “main solid content”.

The molding raw material may contain various additives in addition to the starch. Specific examples of the additive include a bulking agent, a strength adjusting agent, a plasticizer, an emulsifier, a stabilizer, a homogeneity adjusting agent, a moisturizing agent, a handling adjusting agent, a conductivity adjusting agent, a dielectric loss adjusting agent, and a swelling agent. , Colorants and the like.

These additives have advantages in the manufacturing process such as improving the production efficiency of the biodegradable molded product and avoiding problems in the manufacturing process, and the resulting biodegradable molded product. The biodegradable molded product which is a finished product, such as improving the quality of the product and reducing the cost of the biodegradable molded product, can be mentioned. These additives are not particularly limited as long as they do not significantly deteriorate the quality of the foamed molded product and the biodegradable molded product.

The above-mentioned extender is an additive for increasing the amount of the molding raw material by adding it to the molding raw material to reduce the amount of the main raw material starch to be used as much as possible to reduce the cost. Therefore, it is not particularly limited as long as it is cheaper than starch, but preferably a by-product associated with the processing / manufacturing of food or the like which also serves as waste treatment can be preferably used.

Specifically, for example, (1) vegetables and fruits such as celery, carrots, tomatoes, citrus fruits (mandarin orange, lemon, grapefruit, etc.), apples, grapes, berries, pineapple, sugar cane, and sugar beet are used as raw materials. Squeezed dregs, squeezed dregs, or a mixture thereof produced during the production and processing of food (food and drink); (2) Produced during the production of processed foods made from grains such as tofu such as okara By-products; (3) Sake lees, shochu lees, brewer's yeast cake, wine yeast cake, or a mixture thereof produced during the production of sake such as sake, shochu, beer, and wine.
(4) Extraction residue of tea, such as coffee, black tea, barley tea, green tea, and oolong tea, tea leaves, or a mixture thereof; (5) soybeans, corn, rapeseed, sesame, etc. A mixture of these;
(6) By-products produced during grain refining such as bran, bran, and chaff, or mixtures thereof; (7) By-products produced during starch production, such as gluten meal; (8) Corn cups, biscuits, wafers, waffles Confectionery, etc.
Baking scraps or a mixture thereof produced during the production of bread products; (9) those obtained by subjecting each of the above byproducts and the like to a drying treatment and / or a crushing treatment; and the like. These may be used alone or in combination of two or more.

The above-mentioned strength adjusting agent is an additive for adjusting the strength of the foamed molded article and the biodegradable molded article (in particular, improving the strength), and is not particularly limited, but specifically, For example, the above-mentioned extenders (1) to
(9) Various by-products; (10) Sugars such as glucose (dextrose), dextrin, or isomerized sugar, or a mixture thereof; (11) Sugar alcohols such as sorbitol, mannitol, lactitol, or a mixture thereof; (12) (13) Carnauba wax, candelilla wax, beeswax, paraffin, microcrystalline wax, and other waxes or mixtures thereof, such as vegetable oils, animal oils, processed oils, and mixtures thereof; 14) Xanthan gum, gellan gum, guar gum, locust bean gum, pectin, arabic gum, karaya gum, tara gum, carrageenan, furcellulan, agar, alginic acid, and salts thereof. Sugars or mixtures thereof; (15) Calci Metal salts such as chlorides, sulfates, organic acid salts, carbonates, hydroxides and phosphates of metals such as um, sodium, potassium, aluminum, magnesium and iron, or mixtures thereof; (16) Quartz powder , Diatomaceous earth, talc, insoluble minerals such as silicon or mixtures thereof; (17) Cellulose, microcrystalline cellulose, paper, pulp (both used pulp and virgin pulp),
Plant fibers such as carboxymethyl cellulose, methyl cellulose, acetyl cellulose and their derivatives, or mixtures thereof; (18) Various structures such as glass, metal, carbon, ceramics and other inorganic substances and fibers made of these; (19) shells, Natural materials such as bone meal, eggshell, leaves, wood meal and mixtures thereof; (20) calcium carbonate, carbon,
Talc, titanium dioxide, silica gel, aluminum oxide, non-fibrous fillers, or mixtures thereof; (21) Fatty acids such as stearic acid, lactic acid and lauric acid, or salts thereof such as metal salts thereof, or fatty acid derivatives such as acid amides and ethers. Or a mixture thereof (22) Other food additives such as glycerin, polyglycerin, propylene glycol, ethylene glycol, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, sugar ester, lecithin, sorbitan fatty acid ester, polysorbate, etc. object,
Or a mixture thereof; (23) a natural resin such as shellac, rosin, sandalac resin, gutta percha, dammar resin, or a mixture thereof; (24) a biodegradable resin such as polyvinyl alcohol, polylactic acid, or a mixture thereof; (25) Acetyltributyl citrate, zirconium salt solution, ammonium zirconium carbonate alkaline aqueous solution, or a mixture thereof; and the like. These may be used alone or in combination of two or more.

The above-mentioned plasticizer is an additive that improves the flow characteristics of the raw material for molding and gives flexibility to the foamed molded product and the biodegradable molded product to be obtained. Include, for example, (1)-
Various by-products of (9); listed as strength modifiers (10) to (21)
And various compounds of (23) and (24); (26) acetyl polybutyl citrate, sugar alcohols such as glycerin, polyglycerin, propylene glycol and ethylene glycol, or a mixture thereof; and the like. These may be used alone or in combination of two or more.

The above-mentioned emulsifier is an additive which, when an oily additive is added to the molding raw material, sufficiently mixes the oily additive into an oil-in-water type emulsion, and is not particularly limited. Although it is not intended, specifically, for example, (27)
Examples thereof include surfactants such as glyceric acid ester, polyglyceric acid ester, propylene glycol fatty acid ester, sugar ester, sorbitan acid ester, lecithin and polysorbate, or a mixture thereof.

The stabilizer is an additive for stabilizing the state of the prepared molding raw material, and is not particularly limited, but specifically, for example, starch as the main raw material described above. (Strictly defined, no modification) or its derivatives; (10) sugars listed in the above strength modifier; (11) sugar alcohols; (14) thickening polysaccharides; (17) vegetable fibers and their derivatives (excluding paper) ); (21) Fatty acid, fatty acid salt, fatty acid derivative; and the like. These may be used alone or in combination of two or more.

The above-mentioned homogeneity adjusting agent is the homogeneity in the slurry-like or dough-like forming raw material, that is, the "texture" of the forming raw material (in this case, particles of the solid content forming the slurry state or the dough-like state). Etc.) is an additive for making the state as fine as possible, uniform and smooth, and is not particularly limited, but specifically, for example,
Starch (in a narrow sense, unmodified) or its derivative as the main raw material described above; various by-products listed in the bulking agent (1) to (9); various compounds listed in the strength modifier (10) to (25) ; And the like. These may be used alone or in combination of two or more.

The moisturizer is for allowing the foamed molded product to contain a certain amount of water, and has the same function as the plasticizer. That is, if the foamed molded product containing starch as the main component is in a state of containing a certain amount of water (moisturizing state), the brittleness of the pregelatinized starch is reduced,
The effect that the strength and flexibility are improved can be obtained. Therefore, the moisturizer also functions as a plasticizer and a strength adjuster.

The moisturizing agent is not particularly limited, but specifically, for example, the above-mentioned starch as the main raw material (in a narrow sense, unmodified) or its derivative; (9) Various by-products; (10) Sugars listed as strength modifiers; (11) Sugar alcohols; (12) Fats and oils; (13) Waxes; (14) Thickening polysaccharides; (15) Metal salts; ( 17) vegetable fibers and derivatives thereof; (19) natural materials such as shells, bone meal, eggshell, leaves, and wood meal; (22) food additives; These may be used alone or in combination of two or more.

The above-mentioned handling adjuster functions as a slurry adjuster, and is an additive for improving the handling property of the molding raw material in the form of slurry or dough, and is not particularly limited. All the materials and compounds mentioned as the above-mentioned plasticizer, emulsifier and stabilizer are included. These may be used alone or in combination of two or more.

The above-mentioned conductivity adjusting agent is a factor for controlling the heat generation state when the foamed molded article is internally heat-generated, as will be described later, in particular when it is internally heat-generated by electric heating. Which is one of the additives for adjusting the dielectric constant of the forming raw material, and is not particularly limited, and specifically, for example, (12) fats and oils mentioned in the above strength adjusting agent; (13) waxes; (14) thickening polysaccharides; (15) metal salts; (28) salts, various water-soluble electrolytes such as acids, alkalis and alcohols; and the like. These may be used alone or in combination of two or more.

The above-mentioned dielectric loss controlling agent is one of the factors for controlling the heat generation state when molding a foamed molded article, especially when it is heat-molded by internally generating heat by high frequency dielectric heating. It is an additive for adjusting the dielectric loss of the raw material and is not particularly limited, but specifically, for example, (12) fats and oils; (13) wax; (15) mentioned in the above strength adjusting agent. Metal salts; (16) Insoluble minerals;
(17) vegetable fiber or its derivative; (28) various water-soluble electrolytes mentioned in the above dielectric constant adjusting agent; (29) zirconium salt, zirconium salt-containing compound such as ammonium zirconium carbonate solution, or a mixture thereof; Can be mentioned. These may be used alone or in combination of two or more.

The puffing agent is an additive for adjusting the degree of foaming of the raw material for molding, or for promoting the expansion of the raw material for molding to obtain a foamed molded article suitable for the shape and application, and is not particularly limited. However, specifically, for example, (30) benzenesulfohydrazine compounds, azonitrile compounds, nitroso compounds, diazoacetamide compounds, azocarboxylic acid compounds and other organic swelling agents and various preparations containing them;
(31) Ammonia swelling agents such as ispata and various preparations containing them; (32) Inorganic swelling agents such as sodium hydrogencarbonate, ammonium alum hydrogen tartrate, magnesium carbonate and the like; and various preparations containing them; and the like. These may be used alone or in combination of two or more.

The colorant is an additive added for the purpose of coloring the entire foam-molded product, and is not particularly limited. Specifically, for example, (33) an inorganic type such as carbon black is used. Pigments; (34) Natural or synthetic organic dyes such as various colorants defined by the color index; (35) Colorants of natural materials such as caramel and cacao powder; and the like. These may be used alone or in combination of two or more.

Here, of the additives contained in the above-mentioned molding raw material, the content of the extender (also sometimes referred to as a bulking additive) is included in the total main solid content of the molding raw material. It is preferably not more than the content of starch.

In the raw material for molding of the present invention, the water to be mixed with starch or its derivative as the main component may be water used for industry and is not particularly limited.

The amount of water added to the above forming raw material is 20% by weight or more and 7% by weight when the forming raw material is 100% by weight.
Within the range of 0% by weight or less, preferably 25% by weight or more and 55
It is within the range of not more than wt%. The amount of water added to the raw material for molding is the above-mentioned main solid content (starch as the main raw material +
25% by weight when the total amount of the raw material components in the molding raw material is 100% by weight, and the additives (functional additives) other than the above-mentioned bulking agent (filling agent) It is in the range of not less than 230% by weight and preferably in the range of not less than 33% by weight and not more than 120% by weight.

When the amount of water added to the molding raw material is within the above range, the molding raw material is in the form of slurry or dough. If the amount of water added to the forming raw material is less than 20% by weight, the amount of water contained in the forming raw material is too small and the fluidity is almost lost, which is not preferable for forming. On the other hand, when it exceeds 70% by weight, the content of water contained in the raw material for molding is too large, and the content of the solid content is excessively reduced, so that sufficient molding cannot be performed, which is not preferable.

Since the molding raw material is in the form of slurry or dough, it becomes possible to easily fill the molding raw material into the cavity of the molding die, and the molding processability is improved. Further, it becomes possible to allow a certain amount of water to remain in the foamed molded product after molding, and the flexibility of the foamed molded product can be improved.

Next, the covering film 12 used in the present invention will be described.

The covering film 12 may be made of a biodegradable plastic as a main component and having a hydrophobic property, that is, one which can impart at least water resistance to the foamed molded product. Further, it is more preferable that the coating film 12 further imparts gas barrier properties, heat insulation properties, abrasion resistance, strength improvement, flexibility and the like. In particular, when the biodegradable molded product according to the present invention is used in a highly-tight storage container or the like, it is necessary to avoid oxidation or moisture absorption of the contents housed therein. It is very preferable that the degradable molded product can impart a gas barrier property, that is, a gas barrier property.

The raw material of the coating film 12 is not particularly limited as long as it is biodegradable and at least exhibits water resistance, preferably gas barrier property after being attached to the surface of the foamed molded product. Not something.

Specifically, for example, 3-hydroxybutyric acid-3-hydroxyvaleric acid copolymer, poly-p-hydroxybenzaldehyde (PHB), polybutylene succinate (PBS), polycaprolactone (PLC), cellulose acetate. -Based (PH) polymer, polyethylene succinate (PESu), polyester amide, modified polyester, polylactic acid (PLA), Matterby (registered trademark, Novamont, Italy: polyvinyl alcohol-based starch-based, biodegradable) Resins and aliphatic polyester-based resins are sub-components), cellulose
Examples include various materials known as so-called "biodegradable plastics" such as chitosan composites. These raw materials may be used alone or in the form of a composite of two or more kinds. In addition, auxiliary materials such as biodegradable plasticizers and fillers may be added to these biodegradable plastics.

Further, the coating film 12 may be prepared by mixing starch with each of the above raw materials (biodegradable plastic). In this case, the mixing ratio of the biodegradable plastic to starch is not particularly limited as long as various functions such as hydrophobicity of the coating film 12 are not deteriorated, but for example, the mixing ratio is about 1: 1 by weight. Ratios can be preferably used.

In addition, various additives may be added to the coating film 12. Specific additives include, for example, a colorant, an additive capable of improving water resistance and gas barrier properties, an additive capable of improving various properties in softening at the time of application, and the like, but are not particularly limited. is not.

The thickness (film thickness) of the covering film 12 is not particularly limited, but a film or sheet within a range of 0.01 mm or more and a few mm or less may be used before being attached to the foamed molded product. It should be.

Further, since the covering film 12 is heated and softened to be stuck on the surface of the foamed molded product, as described later, the thickness after sticking is smaller than the above range. . The thickness of the covering film 12 after the sticking is appropriately set to such a thickness that water resistance and gas barrier properties can be exhibited according to the type of biodegradable plastic as a raw material, and is not particularly limited. However, the upper limit is preferably 80 μm or less, and more preferably 50 μm or less. Regarding the lower limit, the thickness may be such that water resistance and gas barrier properties can be exhibited as described above, but in general, 5 μm or more is preferably used.

The weight of the coating film 12 is preferably less than 40% by weight based on the total weight of the biodegradable molded product. Therefore, it is desirable that the thickness of the covering film 12 be set so as to satisfy this weight ratio. According to this, by suppressing the amount of the biodegradable plastic having a relatively slow biodegradation rate, the biodegradable molded article as a whole can exhibit very good biodegradability.

As a preferred molding method in the present invention,
A deep-drawing mold having a cavity matched to the desired shape of the molded product and comprising at least two or more parts is used, and the molding raw material and the coating film are put into the cavity of the mold. A method of molding the foamed molded product and the covering film by heating and pressurizing the same can be mentioned.

Therefore, the deep-drawing mold has two or more metals that have cavities matching the desired shape of the molded product and that can be divided so that the foamed molded product can be taken out after molding. An example is a configuration including a mold piece made of metal. When a biodegradable container is manufactured as a biodegradable foamed molded product, a mold comprising a metal convex mold piece (convex mold) and a metal concave mold piece (concave mold) that fit together is preferably used.

As the deep-drawing mold comprising the convex piece and the concave piece, specifically, the metallic convex piece (convex) 21a and the metallic concave piece (shown in FIG. 4A) are used. Concave)
Examples include a mold 20a composed of a pair of 22a, a metal convex mold piece (convex mold) 21b and a metal concave mold piece (concave mold) 22b shown in FIG. 5A, and the like.

Further, in FIGS. 4 and 5, the upper and lower split molds are shown as examples of the split molds, but the way of splitting in the split molds (that is, the number of mold pieces).
Is not limited to upper and lower halves. For example, instead of the two-piece mold 20b shown in FIG. 5, a convex piece 21c having the same shape as the convex piece 21b as shown in FIG.
And a three-divided mold 20c composed of two concave mold pieces 23c and 24c having a shape obtained by dividing the concave mold piece 22b into two.
It is also possible to use.

The mold 20a, the mold 20b, and the mold 20c are the convex piece 21a and the concave piece 22a, the convex piece 21b and the concave piece 22b, and the convex piece 21c and the concave piece 23, respectively.
FIG. 4 (b) and FIG. 5 with the combination of c and 24c.
As shown in (b) and FIG. 6 (b), cavities 25a and 25b adapted to the shape of the desired foam molded article (see FIGS. 2 and 3) are formed inside.

Although not shown, the molds 20a.2 are also provided.
0b and 20c include knockout pins for taking out the foamed molded product, the convex mold pieces 21a, 21b and 21c,
A hinge, a guide, or a bar that movably connects the concave pieces 22a, 22b, 23c, and 24c may be provided.

Further, using the mold 20a, the cavity 2
By sandwiching the molding raw material in 5a between the two covering films 12 and heating and pressurizing it, the bowl type container 10a shown in FIG. 2 (a) is obtained, and the molds 20b and 20c are used. The molding raw material in the tee 25b is sandwiched between the two covering films 12 and heated and pressed to obtain the cup-shaped container body 10b shown in FIG. 3 (a).

In the present embodiment, the molds 20a, 20b, 20c are mentioned as an example of the mold, but the molds are not limited thereto, and various conventionally known molds can be used. Also, its shape can be appropriately selected according to the shape of the foamed molded product.

However, as will be described later, the mold used in the present invention is required to have heat resistance for steam foam molding, as well as strength and abrasion resistance. Further, when the internal heating is performed using microwaves, microwave transparency is required. Therefore, in the internal heating using microwaves, as the molding die, a molding die made of resin or ceramic having microwave transparency, heat resistance, strength, and abrasion resistance is preferably used. In this case, the metal mold is more preferable because the mold itself also acts as a part of the electrode in the case of energization and internal heating using high frequency dielectric as will be described later.

Next, a heating method during molding will be described.

As the heating method during the above-mentioned molding, for example, external heating by direct heating means for directly heating the molding die such as direct fire, far infrared ray, electric heater, IH heating device, energization heating, high frequency dielectric heating, microwave Internal heating by an internal heating means for heating the internal forming raw material itself, such as heating, can be used, and these can also be used in combination.

In the case of internal heating, the molding raw material itself is heated. Therefore, the covering film 12 is heated by the high-temperature molding raw material in the foam molding process and is attached to the surface of the foam molded product. Therefore, if the internal heating is used, the coating film 12 is not directly heated by the mold, so that the coating film 12 containing a biodegradable plastic having a relatively low melting point as a main component can be used.

On the other hand, in the external heating, since the coating film 12 is directly heated by the molding die, the molding raw material inside the coating film 12 is also heated, so that the molding raw material is sufficiently foam-molded. Will be applied to the covering film 12 at a considerably high temperature. Therefore, it is preferable to use a film having a higher melting point as the coating film 12, and the heating temperature of the mold must be set more finely in consideration of the melting point and the softening point of the coating film 12.

Therefore, in view of the ease of attachment and the range of selection of the covering film 12, the internal heating is more versatile as the heating method.

However, in the external heating, since the coating film 12 is directly heated from the molding die, there is an advantage that the softening of the coating film 12 and the adhesion to the surface of the foamed molded product can be easily controlled. Further, in the case of the coating film 12 having a high softening point, if internal heating is used and the molding raw material is heated to such an extent that the coating film 12 is sufficiently softened, it may be excessively foam-molded depending on the type of the molding raw material. In some cases, external heating may be preferable because the quality of the foamed molded product may be deteriorated.

As described above, since the heating method has advantages of both external heating and internal heating, the condition of the heating method depends on what kind of biodegradable molded product is to be produced.
The conditions are appropriately selected such as external heating, internal heating, or a combination thereof, and are not particularly limited.

In the case of external heating, the molding die (mold 20a etc.) is directly heated by the above direct heating means. As a result, the molding raw material in the cavity (cavity 25a, etc.) is externally heated from the molding die, and the foaming molded article is molded by steam-foaming the molding raw material.

On the other hand, in the case of internal heating, a mold having the same shape as the above-mentioned forming die for external heating can be used. For example, as schematically shown in FIG. 8, a mold 20a including a convex mold piece 21a and a concave mold piece 22a is used, and the electrode 26 and the electrode 26 are connected to the convex mold piece 21a and the concave mold piece 22a, respectively. An insulator 27 is arranged at a contact portion between the mold piece 21a and the concave mold piece 22a, and the electrode 26.
A heating device having a power source 28 connected to 6 can be used. As a result, the molding raw material filled in the cavity 25a can be internally heated. The electrode 26 is connected to a switch, a control circuit, and the like (not shown) in addition to the power source 28.

The configuration in which the electrodes 26 are arranged on the convex pieces 21a or the concave pieces 22a can be applied to the case of the external heating. That is, even in the case of external heating, it is possible to employ a configuration in which the heating means and the electrode 26 are directly arranged in order to directly heat the molding die. Therefore, the configuration shown in FIG. 8 in which the electrodes 26 are arranged can be used for both external heating and internal heating.

Dielectric heating is particularly preferable as the internal heating. According to the dielectric heating, the molding raw material generates heat in a short time at the initial stage of foam molding, and the whole expands at once.
As a result, the pressure of pressing the coating film 12 against the mold is strong and uniform. Further, by controlling the temperature of the molding die and the heat generation of the molding raw material, the molding film contact surface (the surface in contact with the molding die) of the covering film.
It is also possible to raise the temperature of the adhesive surface (the surface to be adhered to the coating film) of the foamed molded article to near the melting point while suppressing the temperature to or below the melting point. As a result of these, it is possible to obtain a biodegradable molded product in which the foamed molded product and the covering film 12 have high adhesion.

The above-mentioned dielectric heating is a method of heating an object to be heated by dielectric loss of the object to be heated, and high frequency (HF; 3 to 30 MHz) is applied to the object to be heated (dielectric) to perform the dielectric heating. There are high-frequency dielectric heating and microwave heating in which a microwave (HF; 1 to 100 GHz) is applied to an object to be heated (dielectric) to perform dielectric heating. Of these, high frequency dielectric heating can perform dielectric heating by using a metal "mold" as an electrode, an output device (high frequency generator)
It is more preferable in that the heat generation of the raw material for molding can be easily controlled because the precise output control can be performed.

Next, one embodiment of a method for producing a deep-drawn biodegradable molded article according to the present invention will be described with reference to FIG. In addition, here, the convex piece 21 shown in FIG.
bowl mold 20a comprising a and a concave piece 22a
Will be described in more detail by taking as an example the case where the bowl type container 10a is manufactured by using.

In the method for producing a biodegradable molded product according to the present embodiment, as shown in FIG. 1, a starch or a derivative thereof as a main component is mixed with water to obtain a slurry or dough-shaped molded product. A bowl type container 10a (see FIG. 2) is manufactured by using the raw material 14 and two coating films 12 having a biodegradable plastic as a main component and having hydrophobicity.

First, as shown in FIG. 1, the convex mold piece 21a and the concave mold piece 22a of the mold 20a divided into two are replaced by the convex mold piece 2a.
1a and the center of the concave mold piece 22a are aligned on the vertical line, and the convex mold piece 21a is arranged on the upper side and the concave mold piece 22a is arranged on the lower side. In addition, the convex surface (lower surface) of the convex piece 21a
And the concave surface (upper surface) of the concave piece 22a are made to face each other so that the distance along the vertical line is substantially equal at any position.

Next, between the convex mold piece 21a and the concave mold piece 22a, the molding raw material 14 and the two non-preformed covering films 12 are arranged in a substantially planar shape. At this time, the two covering films 12 are arranged so as to be spaced from each other and parallel to each other, and a slurry-like or dough-like forming raw material 14 is provided between the two covering films 12.
To supply. In addition, the coating film 12 has a convex piece 21a.
Are arranged so as to be perpendicular to a straight line connecting the center of the concave mold piece 22a and the center of the concave mold piece 22a, and in this case, they are arranged horizontally.

As a method of arranging the covering film 12 in a substantially plane shape, simply disposing the covering film 12 in a substantially plane shape in the mold 2
0a, a method of fixing the curled coating film 12 on both sides of the mold 20a, or the like may be used. However, the coating film 12 may be formed into a convex piece 21a by using a plurality of rollers arranged on both sides of the mold 20a. The coating film 12 can be continuously supplied by passing it between the concave piece 22a and the concave piece 22a.

Then, the container body 11a is steam-foam molded by heating (pressurizing) the molding raw material 14 and the coating film 12 in the mold 20a using the above-described external heating and / or internal heating. At the same time, the covering film 12 is softened and pressure-bonded (attached) to the surface of the container body 11a. By this one step, the bowl type container 10a as the biodegradable molded product according to the present invention can be molded.

This molding raw material 14 and the covering film 1
2 is heat-molded, the convex mold piece 21a and the concave mold piece 22a
At least one of them is moved in a direction in which the convex mold piece 21a fits into the concave mold piece 22a. As a result, first, FIG.
As shown in FIG.
The center portion of the upper coating film 12 is pressed by the convex mold and begins to deform. Then, the central portion of the coating film 12 is deformed so as to approach the shape of the surface of the convex mold piece 21a as shown in FIG. 7B, and finally the convex mold piece 21a fits into the concave mold piece 22a. At this point, it is molded into a shape that is substantially the same as the surface of the convex piece 21a. Note that, in FIGS. 7A and 7B, only the covering film 12 is shown for simplification of the drawings.

In this way, the central portion of the covering film 12 is deformed and molded by the pressing by the convex mold piece 21a. At this time, since the convex piece 21a has a deep drawing shape, the covering film 12 is significantly stretched. Therefore, it is important to optimize the speed at which the covering film 12 is stretched.

The speed at which the covering film 12 is stretched is such that the convex piece 21a with respect to the covering film fixing plane A (see FIG. 7 (b)) while the covering film 12 is deformed.
Depends on the relative moving speed of. Here, the covering film fixing plane A is a plane formed by connecting the surfaces of the undeformed portion of the outer periphery of the covering film 12 (in this case, the portion fixed to the upper end of the concave mold piece 22a).

Therefore, in the manufacturing method of the present embodiment, at least while the covering film 12 is deformed, the relative moving speed of the convex piece 21a to the covering film fixing plane A is in the range of 8 mm / s to 12 mm / s. It is preferable to keep it inside.

As a result, the speed at which the coating film 12 is stretched by the convex piece 21a is kept substantially constant and at an optimum speed, so that the coating film 12 is prevented from being torn, cracked, or pinhole. it can. When the relative moving speed of the convex piece 21a with respect to the covering film fixing plane A is higher than 12 mm / s, the covering film 12 is rapidly stretched, so that tears or cracks are likely to occur. On the contrary, if the relative moving speed of the convex piece 21a with respect to the covering film fixing plane A is slower than 8 mm / s, pinholes are apt to occur in the covering film 12 although the cause is not clear.

In particular, in the manufacturing method of this embodiment, since the deep-drawing shaped article (the bowl type container 10a) is manufactured by using the substantially flat cover film 12, the cover film 1
2 is significantly stretched. Therefore, the biaxially stretched film having particularly excellent heat resistance and gas barrier property is used as the coating film 1
When used as No. 2, it is relatively difficult to stretch the coating film 12 so that the coating film 12 is free from tears, cracks, and pinholes. However, by setting the moving speed within the above numerical range, it is possible to avoid the occurrence of tears, cracks, and pinholes in the coating film 12 even in such a case. As a result, the covering film 1
Since the container body 11a can be more surely covered by No. 2, the water resistance of the bowl type container 10a can be more surely ensured.

In the method of this embodiment, the covering film 12
Since the outer peripheral portion of is fixed to the upper end of the concave mold piece 22a, the covering film fixing plane A is at a predetermined distance from the upper end surface of the concave mold piece 22a. Therefore, the relative moving speed of the convex piece 21a with respect to the covering film fixing plane A is
Is equal to the relative approach speed of the concave piece 21a. on the other hand,
Instead of fixing the outer peripheral portion of the covering film 12 to the upper end of the concave piece 22a as in the method of the present embodiment, it is possible to fix the outer peripheral portion of the covering film 12 by using some fixing means separately. In that case, the relative moving speed of the convex piece 21a with respect to the covering film fixing plane A is not the relative approaching speed of the convex piece 21a and the concave piece 21a,
It becomes equal to the relative moving speed of the convex piece 21a and the fixing means.

Further, in the method of the present embodiment, during the period when the covering film 12 is deformed, the covering film 12 starts to be deformed by being pressed by the convex piece 21a (FIG. 7).
From the time when the convex piece 21a shown in (a) first contacts the upper covering film 12), the covering film 12 becomes the convex shape 2
At the time of molding into a shape substantially the same as the surface of 1a (Fig. 7 (b))
The time until the convex piece 21a shown in (4) is fitted into the concave piece 22a).

The numerical range of the relative moving speed described above is
It is based on an experiment using a coating film 12 having a thickness of 20 to 80 μm. However, even when the coating film 12 having another thickness is used, by setting the relative moving speed of the convex piece 21a with respect to the coating film fixing plane A within the above-mentioned numerical range, the thickness of 20 to 80 μm can be obtained. It is expected that substantially the same effect as when using the covering film 12 is obtained.

In the manufacturing method of this embodiment, it is preferable that the convex pieces 21a and the concave pieces 22 are linearly brought close to each other at least while the covering film 12 is deformed. That is, the relative movement of the convex piece 21a with respect to the concave piece 22 is preferably a linear movement.

According to the above method, for example, the convex piece 21a
One side of the concave piece 22 and one side of the concave piece 22 are connected by a hinge, and the convex piece 2
The pressure applied to the coating film 12 by the convex mold piece 21a becomes more uniform as compared with the case of rotating 1a. Therefore, the coating film 12 can be stretched uniformly, and the thickness of the coating film 12 becomes uniform. Therefore, the effect of the coating film 12, that is, the water resistance of the biodegradable molded product is further improved.

In the manufacturing method of this embodiment, while the covering film 12 is deformed, the relative moving speed of the convex piece 21a with respect to the covering film fixing plane A is 8 mm / s to 12 mm.
When kept within the range of mm / s, the time required from the deformation start time of the coating film 12 to the time when the convex mold piece 21a fits into the concave mold piece 22a is limited within a specific range determined by the shape of the mold 20a. It On the other hand, the covering film 12
The relative moving speed of the convex piece 21a with respect to the covering film fixing plane A until the deformation of the convex shape can be set arbitrarily.

Therefore, in the manufacturing method of this embodiment, it is preferable that both the convex mold piece 21a and the concave mold piece 22a be moved in the directions toward each other until at least the deformation of the coating film 12 is started.

According to the above method, since both the convex piece 21a and the concave piece 22a are moved in the direction of approaching each other at least until the covering film 12 starts to deform, the convex piece 21a is fitted to the concave piece 22a. It is possible to shorten the time (fitting time) required until the production is completed, and as a result, it is possible to shorten the manufacturing time.

When both the convex mold piece 21a and the concave mold piece 22a are moved toward each other, the convex mold piece 2
Both the convex mold piece 21a and the concave mold piece 22a may be moved toward each other until 1a fits into the concave mold piece 22a. However, the convex mold piece 21a and the concave mold piece 22a may be moved until the covering film 12 starts to deform. It is preferable to move both of them in a direction of approaching each other, while moving only the convex piece 21a after the covering film 12 starts to deform. This makes it unnecessary to move the covering film 12 when the covering film 12 is held in a substantially flat shape such as when the covering film 12 is continuously conveyed, and the operation is simplified.

The heating temperature of the mold 20a during the heat molding is within a temperature range in which the covering film 12 can be softened without being melted and pressure-bonded to the surface of the foamed molded article, that is, the softening point of the covering film 12 or more, the covering film. The temperature may be lower than the melting point of 12, but is preferably set according to the thermal characteristics of the covering film 12 used. The temperature of the mold 20a is set so that the coating film 1 is heated during the heat molding.
It is preferable that the temperature is not lower than the softening point of 2 and is 10 ° C. or more lower than the melting point of the coating film 12.

As a result, it is possible to prevent the covering film 12 from being softened without being melted and formed into a shape corresponding to the mold 20a, and thus the covering film 12 from having pinholes. Therefore, the container body 11a can be more surely covered with the covering film 12, so that the water resistance of the bowl type container 10a can be more surely ensured.

The heating at the time of thermoforming is performed by saying that "the temperature of the mold 20a is equal to or higher than the softening point of the covering film 12 and the covering film 1
It is more preferable to satisfy the temperature condition of 10 ° C. or more lower than the melting point of 2 and 130 ° C. or more ”(hereinafter referred to as temperature condition A). As a result, since the slurry-like or dough-like forming raw material 14 in the cavity (cavity 25a etc.) can be sufficiently heated for steam foam molding, the molding time of steam foam molding can be shortened and the steam foam molding can be performed. The condition is satisfied, and the container body 11a having a uniform and dense structure is obtained. Therefore, the manufacturing time can be shortened and the characteristics such as strength of the bowl type container 10a can be improved.

The heating at the time of thermoforming is performed by saying that "the temperature of the mold 20a is equal to or higher than the softening point of the covering film 12 and the covering film 1
It is more preferable to satisfy the temperature condition of 10 ° C. or more lower than the melting point of 2 and 150 ° C. or more ”(hereinafter referred to as temperature condition B). As a result, the slurry-like or dough-like forming raw material 14 in the cavity (cavity 25a or the like) can be heated more sufficiently to be steam foam-molded, so that the molding time of steam foam-molding can be further shortened. At the same time, the steam foaming conditions are further improved, and the container body 11a has a more uniform and dense structure.
Is obtained. Therefore, the manufacturing time can be further shortened, and the characteristics such as the strength of the bowl type container 10a can be improved.

In order to satisfy the temperature condition A, it is necessary to use the covering film 12 having a softening point of 130 ° C. or higher and a melting point of 140 ° C. or higher, and in order to satisfy the temperature condition B. As the coating film 12, it is necessary to use the coating film 12 having a softening point of 150 ° C. or higher and a melting point of 160 ° C. or higher.

By using the coating film 12 having such a softening point and a melting point, it is possible not only to satisfy the above temperature conditions but also to obtain a bowl-type container 10a having high heat resistance in which softening and melting hardly occur. In particular, when the bowl type container 10a is used as a cup noodle vessel or the like, it is possible to more reliably avoid deformation or melting of the bowl type container 10a due to heat of hot water or the like poured into the bowl type container 10a.

Therefore, the thermal characteristics of the covering film 12 are preferably such that the heating temperature at the time of thermoforming can be set to a high temperature and the heat resistance of the bowl type container 10a can be improved. Specifically, the softening point of the coating film 12 is more preferably 120 ° C. or higher, and 1
The temperature is more preferably 30 ° C. or higher, further preferably 150 ° C. or higher. The melting point of the covering film 12 is preferably 150 ° C. or higher, and 170 ° C.
More preferably, it is more preferably 200 ° C. or higher. Further, the covering film 12 preferably has a softening point of 120 ° C. or higher and a melting point of 150 ° C. or higher, a softening point of 130 ° C. or higher, and a melting point of 170 ° C. or higher. Preferably
Most preferably, the softening point is 150 ° C or higher and the melting point is 200 ° C or higher.

The upper limit of the heating temperature of the mold 20a is not particularly limited as long as it is lower than the melting point of the coating film 12, but is 240 ° C. or lower in order to avoid thermal change of the bowl type container 10a. preferable.

In addition, the steam foam molding is performed by using the molding raw material 14
This is a molding method in which bubbles are generated by evaporating water contained therein to generate water vapor. for that reason,
In the production method according to the present invention, in order to form the molding raw material 14 by steam foam molding, the molding raw material 14 has a boiling point of 10% of water.
It is necessary to heat to 0 ° C or higher.

Therefore, when only external heating is used as the heating method, the heating temperature of the mold 20a is 100
It is necessary that the temperature is not lower than 0 ° C, and it is more preferable that the temperature is sufficiently higher than the boiling point of water of not lower than 100 ° C, specifically, not lower than 140 ° C. As a result, the water contained in the forming raw material 14 is always evaporated to become water vapor and bubbles are generated.
Therefore, the obtained molded product must be steam-foamed, and the foamed molded product can be easily obtained.

Therefore, when external heating is used as the heating method, it is necessary to select, as the coating film 12, a film mainly composed of biodegradable plastic having a melting point of 100 ° C. or higher. If the coating film 12 contains a biodegradable plastic having a melting point of less than 100 ° C. as a main component, the coating film 12 will be completely melted at the temperature for sufficiently steam-foaming the molding raw material 14, and The film 12 cannot maintain the film shape.

On the other hand, when only the internal heating is used as the heating method, or when the external heating and the internal heating are used in combination, a low frequency AC voltage or a high frequency electric field is applied to the electrode 26 to cause the cavitation. Since the molding raw material 14 itself in the tee (cavity 25a etc.) is internally heated, the heating temperature also depends on various conditions related to the internal heating and is not particularly limited.
May be at or above the temperature at which steam foams. Therefore,
When the internal heating is used, it is possible to use the coating film 12 having a relatively low melting point as compared with the external heating.

[0169] As various conditions relating to the internal heating, specifically, the characteristics of the electrode 26 and the magnitude of the above-mentioned low-frequency AC voltage and high-frequency electric field are greatly involved. It also largely depends on the conductivity and dielectric loss of the raw material 14. That is, when heat molding is performed by electric heating, the heat generation state is controlled by the conductivity of the molding raw material 14, and when heat molding is performed by high frequency dielectric heating,
This is because the heat generation state is controlled by the dielectric loss of the forming raw material 14. The practical setting range of the above various conditions is not particularly limited as long as it is set so that the temperature in the cavity is in the same temperature range as the external heating in practical use.

The heating time is appropriately set according to the heating temperature and the shape and thickness of the container body 11a, but at least the water content of the container body 11a after molding falls within a predetermined range. Such time is preferable. In other words, it is preferable that the time is such that the water in the forming raw material 14 is not almost completely evaporated.

If the heating time is extended for a long time until the water content of the container body 11a becomes smaller than the above-mentioned predetermined range, the container body 11a will be in an excessively foamed state and will not have a predetermined water content. However, it becomes hard and brittle, which deteriorates the quality of the container body 11a, which is not preferable.

The specific heating time is not particularly limited. For example, when high frequency dielectric heating is performed, molding can be performed in a much shorter time than general external heating, and when the container body 11a is thick, the heating time tends to be long. Therefore, the heating time is basically set appropriately according to the heating method, the shape of the container body 11a, etc.
It is preferably within the range of 0 seconds to 5 minutes.

The molding pressure at the time of heat molding is not particularly limited, but generally, for example, 5 kg.
/ Cm ² or more and 50 kg / m ² or less is preferably used. Of course, this molding pressure can be changed according to various conditions.

Further, in the manufacturing method of the present embodiment, it is preferable to dispose a slip agent on the surface of the mold 20a which comes into contact with the coating film 12 before the heat molding. This allows
Since the contact friction between the surface of the coating film 12 and the surface of the die 20a can be reduced, when the coating film 12 is stretched by the die 20a, the friction with the die 20a causes the coating film 12 to be broken or cracked. It is possible to avoid damage.

Any slip agent may be used as long as it can reduce friction between the surface of the mold 20a and the surface of the coating film 12, and higher aliphatic alcohols, fatty acid amides, metal soaps such as magnesium stearate, and fatty acids. In addition to those generally called "lubricants" such as ester-based compounds and their complexing agents, fats and oils such as vegetable fats and oils, inorganic fine particles, fluororesins and the like can be used. The slip agent may be arranged on the surface of the mold 20a by applying a liquid such as lubricant or oil on the surface of the mold 20a, by attaching fine particles such as inorganic fine particles on the surface of the mold 20a, Examples of the method include forming a solid layer such as a fluororesin coating on the surface of 20a, and a method of forming a solid layer on the surface of the mold 20a is preferable. A fluororesin layer is preferable as the solid layer formed on the surface of the mold 20a.
Therefore, the slip agent is most preferably a fluororesin layer (fluororesin coating, so-called fluororesin coating) formed on the surface of the mold 20a.

This is because the liquid slip agent is applied to the mold 20.
a When applying it to the surface or applying a slip agent in the form of fine particles to the mold 2
When it is adhered to the surface 0a, the slip agent peels off from the surface of the mold 20a during molding, so it is necessary to apply the slip agent each time molding is performed. On the other hand, when the fluororesin layer is formed as the slip agent on the surface of the mold 20a, the slip agent does not peel off from the surface of the mold 20a during molding, and can be used for a long time. Therefore, the labor of disposing the slip agent on the surface of the mold 20a can be reduced.

When the liquid slip agent is applied or the fine particle slip agent is adhered, the slip agent adheres to the surface of the bowl-shaped container 10a during molding. Therefore, after molding, the surface of the bowl-shaped container 10a is formed. It is necessary to remove the slip agent from the. On the other hand, in the above method, the slip agent does not adhere to the surface of the bowl type container 10a during molding and the surface of the bowl type container 10a is not contaminated, and it is possible to save the labor of removing the slip agent from the surface of the bowl type container 10a after molding. it can.

As the fluororesin, tetrafluoroethylene resin (so-called "Teflon (registered trademark)"), tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin Examples thereof include tetrafluoroethylene-ethylene copolymer resin, trifluoroethylene chloride resin, vinylidene fluoride resin, and the like, and the tetrafluoroethylene resin is particularly preferable because it has excellent heat resistance and is inexpensive.

As described above, the manufacturing method of this embodiment is
Slurry-like or dough-like forming raw material 1 obtained by mixing starch or a derivative thereof with water
4 and a coating film 12 having a biodegradable plastic as a main component and having hydrophobicity, using a deep drawing die 20.
The coating film 12 is arranged in a substantially flat shape together with the molding raw material 14 in a, and the molding raw material 14 and the coating film 12 are heat-molded in the mold 20a to obtain the container body 11
This is a method for manufacturing the bowl type container 10a by steam-foaming a and simultaneously softening the cover film 12 and pressing it onto the surface of the container body 11a.

In addition, the manufacturing method of this embodiment uses the convex piece 2
1a and a concave mold piece 22a are used as a mold 20a, and the raw material for molding 14 and the coating film 12 are arranged between the convex mold piece 21a and the concave mold piece 22a before heat molding.
At the time of heat molding, the central portion of the covering film 12 is deformed by moving at least one of the convex mold piece 21a and the concave mold piece 22a in a direction in which these are fitted, and at least while the covering film 12 is deformed, the covering film 1
2 Convex mold piece 21a with respect to the covering film fixing plane A formed by connecting the surfaces of the non-deformable portion of the outer circumference
This is a method of maintaining the relative moving speed of (4) within the range of 8 mm / s to 12 mm / s.

Further, in the manufacturing method of the present embodiment, heating is performed so that the temperature of the mold 20a is equal to or higher than the softening point of the coating film 12 and lower than the melting point of the coating film 12 by 10 ° C. or more. Is the way to do it.

In the manufacturing method described above, the mold 20a is used.
Although the case of manufacturing using the bowl type container 10a has been described, the cup type container 10b, etc. is used by using a deep drawing type mold having another shape such as the mold 20b and the mold 20c. Biodegradable molded articles having other shapes such as the above can be manufactured in the same manner.

The above-described manufacturing method is particularly suitable for manufacturing a deep-drawing biodegradable molded product, but the method of heating under the above heating conditions is the dish type container 1
It is also useful for producing a biodegradable molded product having a large size in the direction in which it spreads in a plane, such as 0b.

In the manufacturing method described above, the convex piece 21
b is arranged on the upper side and the concave piece 22b is arranged on the lower side.
2b may be arranged on the upper side and the convex piece 21b may be arranged on the lower side. Also,
Here, the convex piece 21b and the concave piece 22b are arranged in the vertical direction, and the convex piece 21b and the concave piece 22b are moved in the vertical direction. However, the arrangement direction and the moving direction of the convex piece 21b and the concave piece 22b are described. Is not particularly limited and may be, for example, in the horizontal direction.

Further, in the above-described manufacturing method, the molding raw material is sandwiched between the two covering films 12 and the entire surface of the foamed molded product is covered with the covering film 12 in the steam foam molding using the molding die. However, in the present invention, only the upper surface of the foamed molded product is covered with the coating film 12
You may coat with.

On the other hand, for example, a cup noodle container (see FIG.
As shown in (a) and (b), such as the bowl type container 10a), not only do you put boiling water in the inside, but also the entire container so that the inside dried noodles do not oxidize or absorb moisture. When the gas barrier property is required, it is preferable to adhere the coating film 12 to the entire container.

[0187] The deep-drawn biodegradable molded product produced by the present invention is, for example, a molded product for packaging such as a cushioning material for packaging, guess, a tray for packaging, instant noodles such as cup noodles, cup udon and cup yakisoba. It can be suitably used as a container, a one-way plate or tray used for a food service, or a food container such as a container for soup or juice. Further, the shallow drawing-shaped biodegradable molded article produced in the present invention is a cushioning material for packaging,
It can be suitably used as a food product container such as a guise, a molded article for packaging such as a packaging tray, or a one-way system plate or tray used for a food service.

In particular, since the biodegradable molded article produced by the present invention has water resistance, it can be suitably used as a container for food with a large amount of water, and also has gas barrier properties and the like. It can also be suitably used as a container for instant foods that can be stored for a certain period of time. In particular, since the biodegradable molded article produced by the present invention has high hot water resistance, it can be suitably used as a container for instant noodles such as cup noodles and cups to which hot water is poured during use.

[0189]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto.

[Molding Raw Material] First, various starches (including derivatives), which are main raw materials, various additives, and water are uniformly mixed with a mixer so as to have the composition shown in Table 1, and a slurry-like molding raw material is obtained. (1) to (3) and (7) and dough-shaped forming raw materials (4) to (6) and (8) were prepared.

[0191]

[Table 1]

[Coating Film] As the covering film, five kinds of covering films F1, F2, F3 and F shown in Table 2 are used.
4 and F5 were prepared.

[0193]

[Table 2]

[Example 1] Regarding all combinations (40 types in total) of 8 types of molding raw materials (1) to (8) shown in Table 1 and 5 types of coating films F1 to F5 shown in Table 2 The bowl type container 10a was manufactured by the manufacturing method described with reference to FIG.

At this time, as the heating method, the external heating for heating the mold 20a by using the electric heating heater and the internal heating by the high frequency dielectric heating were used together.

In this embodiment, the temperature of the mold 20a is set to 90 for all 40 types of raw material combinations described above.
℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140
℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190
It was manufactured under 12 kinds of heating conditions, which were set to 0 ° C and 200 ° C, respectively.

480 kinds of bowl type containers 10 thus obtained
With respect to a (sample), the foam moldability, the state of the coated film after molding, and the water resistance were evaluated. Regarding the foam moldability, the fineness and uniformity of the foam structure of the container body 11a were investigated. In addition, regarding the state of the coated film after molding, after visually checking for abnormalities such as tearing and melting, dip the sample with no abnormality in the pinhole of the coated film by immersing it in colored water containing a surfactant. I checked for the presence.

As a result, the following results were obtained irrespective of the type of molding raw material and coating film. That is, when the temperature of the mold 20a was lower than the softening point of the covering film, the covering film was broken. Further, when the temperature of the mold 20a was substantially equal to the melting point of the coating film, pinholes frequently occurred in the coating film. Further, when the temperature of the mold 20a was higher than the melting point of the coating film, the coating film melted. On the other hand, in other cases, the coating film was not melted, and was in a good state with no abnormalities such as tears, cracks, and pinholes.

From the above results, the temperature of the mold 20a is not less than the softening point of the coating film and 10% from the melting point of the coating film, irrespective of the raw material for molding and the type of the coating film.
It has been found that it is preferable that the temperature is lower than 0 ° C.

On the other hand, regarding the fineness and uniformity of the foamed structure of the container body 11a, the temperature of the mold 20a should be 1
It was good when the temperature was 30 ° C. or higher, and even better when the temperature of the mold 20a was 150 ° C. or higher.

Therefore, a summary of these results is as follows.
When both the covering film and the container body 11a are good, any one of the covering films F2 to F5 is used as the covering film, the temperature of the mold 20a is equal to or higher than the softening point of the covering film 12, and the melting point of the covering film 12 is 10 or more. It was a case where the temperature was lower than 0 ° C and higher than 130 ° C.

Even in that case, the container body 11
When a is further improved, the coating film F4 or F5 is used as the coating film, and the temperature of the mold 20a is
This was the case where the softening point of the coating film 12 or higher was 10 ° C. or more lower than the melting point of the coating film 12 and 130 ° C. or higher.

Therefore, regarding the softening point of the coating film, it was good when the temperature was 90 ° C. or higher, and more good when it was 130 ° C. or higher. As for the melting point of the coating film, the melting point of 140 ° C. or higher was good, and the melting point of 170 ° C. or higher was better.

Example 2 All combinations (16 types in total) of 8 types of molding raw materials (1) to (8) shown in Table 1 and 5 types of coating films F3 and F5 shown in Table 2 The bowl type container 10a was manufactured by the manufacturing method described with reference to FIG.

At this time, as the heating method, the external heating for heating the die 20a by using the electric heating heater and the internal heating by the high frequency dielectric heating were used together. When the coating film F3 is used, the temperature of the mold 20a during heat molding is set to 130 ° C, and when the coating film F5 is used, the temperature of the mold 20a during heat molding is 160 ° C. Set to.

When both the convex mold piece 21a and the concave mold piece 22a are moved toward each other, the convex mold piece 21a
a and the concave mold piece 22a come into contact with the coating film (until the coating film 12 starts to deform), the convex mold piece 2
Both 1a and the concave mold piece 22a were moved toward each other, while only the convex mold piece 21a was moved thereafter. Then, for all combinations of the above 16 kinds of raw materials, the convex piece 21 when only the convex piece 21a is moved
The moving speed of a was changed from 5 mm / s to 20 mm / s at a constant speed.

With respect to the obtained bowl type container 10a (sample), the foam moldability, the state of the coated film after molding, and the water resistance were evaluated in exactly the same manner as in Example 1.

As a result, the following results were obtained irrespective of the type of molding raw material and coating film. That is, when the moving speed of the convex piece 21a was in the range of 8 mm / s to 12 mm / s, a very good bowl-shaped container 10a was obtained in which the covering film had no abnormalities such as tears, cracks, and pinholes. When the moving speed of the convex piece 21a was lower than 8 mm / s, pinholes were easily generated in the coating film.
On the contrary, when the moving speed of the convex piece 21a is higher than 12 mm / s, the cover film is likely to be torn (fracture or crack) frequently.

[Example 3] Regarding all combinations (total 16 types) of 8 types of molding raw materials (1) to (8) shown in Table 1 and 5 types of coating films F3 and F5 shown in Table 2 The mold 20c shown in FIG. 6 was used to manufacture the cup-shaped container 10b shown in FIG. 3 by the same manufacturing method as that described with reference to FIG.

At this time, as the heating method, the external heating for heating the die 20c by using the heater for electric heating and the internal heating by the high frequency dielectric heating were used together. When the coating film F3 is used, the temperature of the mold 20c during heat molding is set to 130 ° C, and when the coating film F5 is used, the temperature of the mold 20c during heat molding is 160 ° C. Set to.

As the mold 20c, (1) a mold 20c coated with vegetable oil as a slip agent on the surface in contact with the coating film, and (2) magnesium stearate as a slip agent on the surface in contact with the coating film. A die 20c applied, (3) a die 20c formed with a tetrafluoroethylene resin coating as a slip agent on the surface in contact with the coating film, (4) a die 20c having no slip agent on the surface in contact with the coating film, That is, four types of molds 20c having different surface states were prepared. Then, for all combinations of the above 16 types of raw materials, the cup type container 10b was manufactured using the four types of molds 20c.

With respect to the obtained cup-shaped container 10b (sample), the foam moldability, the state of the coated film after molding, and the water resistance were evaluated in exactly the same manner as in Example 1.

As a result, the following results were obtained irrespective of the type of molding raw material and coating film.

That is, in the case of (4) in which the mold 20c having no slip agent was used on the surface in contact with the covering film, tears and pinholes were generated in the covering film, and the covering film F5 was used especially (4 ), Cracks and pinholes occurred remarkably.

On the other hand, a mold 20c having a slip agent on the surface in contact with the coating film was used (1) to
In the case of (3), no tears or pinholes were generated in the coated film. Further, in these cases (1) to (3), the foam moldability was good, and the slip agent was not adversely affected. Further, the surface of the coated film was the most beautiful in the case of (3) using the tetrafluoroethylene resin coating, as the slip agent was not attached.

[0216]

The method for producing a biodegradable molded article of the present invention comprises:
As described above, a starch or a derivative thereof as a main component, a slurry-like or dough-like forming raw material obtained by mixing this with water, and a biodegradable plastic as a main component and a hydrophobic coating film, By heat-molding the above-mentioned molding raw material and the covering film in a molding die, the biodegradable foamed molded product is steam foam-molded, and at the same time, the covering film is softened and pressure-bonded to the surface of the biodegradable foamed molded product. A method for producing a biodegradable molded article, using a mold comprising a pair of a convex mold and a concave mold, prior to the above heat molding, arranging a molding raw material and a coating film between the convex mold and the concave mold, At the time of the heat molding, the central portion of the coating film is deformed by moving at least one of the convex mold and the concave mold in the direction in which they are fitted, and at least the coating film is deformed. During that, with respect to a plane formed by connecting the surface of the non-deformable part of the coating film periphery, the relative moving speed of the convex, 8mm / s~12
This is a method of keeping it within the range of mm / s.

As described above, the method for producing a biodegradable molded article of the present invention comprises starch or a derivative thereof as a main component,
Using a slurry-like or dough-like forming raw material obtained by mixing this with water and a coating film having a biodegradable plastic as a main component and having hydrophobicity, the above-mentioned forming raw material and the coating film are formed in a mold. A method for producing a biodegradable molded article, which comprises subjecting a biodegradable foamed molded article to steam foam molding by steam molding at the same time, and at the same time, softening the coating film to press-bond it to the surface of the biodegradable foamed molded article. It is a method of performing the heating so that the mold temperature is equal to or higher than the softening point of the coating film and lower than the melting point of the coating film by 10 ° C. or more.

According to each of the above methods, a biodegradable molded article having sufficient strength even when it has a complicated shape, sufficient water resistance, and very good biodegradability can be easily produced. Has the effect.

Furthermore, according to each of the above methods, it is possible to more reliably avoid the occurrence of defects in the coating film, particularly when a deep-drawing biodegradable molded product is produced using a substantially planar coating film. Also, it is possible to more reliably ensure the water resistance of the biodegradable molded product.

As described above, the method for producing a biodegradable molded product of the present invention comprises a starch or a derivative thereof as a main component and a slurry or dough-shaped molding raw material obtained by mixing this with water. And a biodegradable plastic as a main component and a coating film having a hydrophobic property, by heat-molding the molding raw material and the coating film in a molding die to form a steam-foam molded biodegradable foamed product. At the same time, a method of manufacturing a biodegradable molded article in which the coating film is softened and pressure-bonded to the surface of the biodegradable foamed molded article, in which the coating film is placed in a deep-drawing mold together with the molding raw material in a substantially planar shape. Then, the above hot molding is performed to produce a deep-drawn biodegradable molded article.

According to the above method, it is possible to easily produce a biodegradable molded article having sufficient strength even when it has a complicated shape, sufficient water resistance, and very good biodegradability. Produce an effect.

Further, according to the above method, a deep-drawing biodegradable molded article such as a bowl type container or a cup type container can be produced in a smaller number of steps.

[Brief description of drawings]

FIG. 1 is an explanatory view illustrating a method for producing a biodegradable molded product according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the shape of a bowl type container as an example of a biodegradable molded article produced by the production method of the present invention.

FIG. 3 is a schematic cross-sectional view and a schematic plan view showing the shape of a cup-shaped container as still another example of the biodegradable molded product manufactured by the manufacturing method of the present invention.

FIG. 4 is a schematic cross-sectional view showing the structure of a forming die for forming the bowl type container shown in FIG.

5 is a schematic cross-sectional view showing an example of the configuration of a forming die for forming the cup-type container shown in FIG.

FIG. 6 is a schematic cross-sectional view showing another example of the configuration of a molding die for molding the cup-shaped container shown in FIG.

7A and 7B are schematic explanatory views showing how the covering film is deformed by the molding die shown in FIG. 4, in which FIG. 7A shows the time when the covering film starts to deform, and FIG. 7B is the middle of the deformation of the covering film. Indicates the point in time.

FIG. 8 is a schematic explanatory view showing an example of a configuration in which electrodes are provided for internal heating in the molding die shown in FIG.

[Explanation of symbols]

10a Bowl type container (biodegradable molded product) 10b Cup type container (biodegradable molded product) 11a Container body (biodegradable foamed molded product) 11b Container body (biodegradable foamed molded product) 12 Covering film 14 Raw materials for molding 20a Mold (molding die) 20b Mold (molding die) 20c Mold (molding die)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29K 1:00 B29K 1:00 105: 04 105: 04 105: 20 105: 20 B29L 9:00 B29L 9:00 22:00 22:00 (72) Inventor Rumi Shinohara 1-1-47 Unobe, Ibaraki-shi, Osaka Nissei Co., Ltd. (72) Shinji Tanaka 1-1-47 Unobe, Ibaraki-shi, Osaka World Stock Company F-term (reference) 4F204 AA01 AA24 AB01 AB02 AB06 AB07 AB11 AB16 AD05 AG03 AG20 AR08 FA01 FB01 FB13 FB22 FB23 FF01 FF05 4F208 AA01 AB02 AD05 AD08 AG03 AG20 AH55 AR06 AR08 MA05 MB01 MB11 MB13 MC03 MG01 MG06 M08 MG01 MH06

Claims (9)

[Claims] 1. A starch or its derivative as a main component,
Using a slurry-like or dough-like molding raw material obtained by mixing this with water and a coating film containing a biodegradable plastic as a main component and having hydrophobicity, the above-mentioned molding raw material and coating film are formed in a molding die. A method for producing a biodegradable foamed product by steam-foaming the biodegradable foamed product by heat-molding at the same time, softening the coating film and press-bonding to the surface of the biodegradable foamed product. And a mold comprising a pair of concave molds, before the heat molding, a molding raw material and a coating film are arranged between the convex mold and the concave mold, and at the time of the heat molding, at least one of the convex mold and the concave mold is The center part of the coating film is deformed by moving it in the direction that fits, and at least while the coating film is deforming, the surface of the undeformed part of the outer periphery of the coating film is To the plane formed by the Bukoto, the relative moving speed of the convex, 8m
A method for producing a biodegradable molded article, characterized in that the biodegradable molded article is kept within a range of m / s to 12 mm / s. 2. The method for producing a biodegradable molded product according to claim 1, wherein the convex mold and the concave mold are linearly brought close to each other at least while the covering film is deformed. 3. The method for producing a biodegradable molded product according to claim 1, wherein both the convex mold and the concave mold are moved in a direction in which they approach each other at least until the coating film starts to deform. . 4. A starch or a derivative thereof as a main component,
Using a slurry-like or dough-like molding raw material obtained by mixing this with water and a coating film containing a biodegradable plastic as a main component and having hydrophobicity, the above-mentioned molding raw material and coating film are formed in a molding die. A method for producing a biodegradable molded article, which comprises subjecting a biodegradable foamed molded article to steam foam molding by heat-molding at the same time, and at the same time softening the coating film to press-bond it to the surface of the biodegradable foamed article, A method for producing a biodegradable molded article, which comprises heating the mold so that the temperature of the mold is equal to or higher than the softening point of the coating film and lower than the melting point of the coating film by 10 ° C. or more. 5. The method for producing a biodegradable molded article according to claim 4, wherein the heating is carried out so that the temperature of the mold is 130 ° C. or higher. 6. The method for producing a biodegradable molded article according to claim 4, wherein the heating is carried out so that the temperature of the mold is 150 ° C. or higher. 7. A starch or its derivative as a main component,
Using a slurry-like or dough-like molding raw material obtained by mixing this with water and a coating film containing a biodegradable plastic as a main component and having hydrophobicity, the above-mentioned molding raw material and coating film are formed in a molding die. A method for producing a biodegradable foamed product by steam-foaming the biodegradable foamed product at the same time by softening the coating film and pressing the biodegradable foamed product on the surface of the biodegradable foamed product by deep-drawing. By arranging the coating film in a substantially flat shape together with the forming raw material in the shaping die, and performing the above-mentioned heat forming,
A method for producing a biodegradable molded article, which comprises producing a deep-drawn biodegradable molded article. 8. The biodegradable molded article according to any one of claims 1 to 7, wherein a slip agent is provided on the surface of the mold contacting the coating film before the hot molding. Manufacturing method. 9. The method for producing a biodegradable molded article according to claim 8, wherein the slip agent is a fluororesin layer formed on the surface of the molding die.