JPH05329952A - Manufacture of decomposable cushioning material - Google Patents

Abstract

PURPOSE:To enable biodegradable resin to cope even with highly foaming without requiring a special chemical foaming agent by a method wherein after raising temperature of a water-containing biodegradable resin granular material together with steam under a pressurized state, the granular material is inflated by opening suddenly, and many inflated granular materials are collected to be integrated. CONSTITUTION:A water-containing biodegradable resin granular material is brought into contact with steam under a pressurized state to raise temperature of the granular material to its softening point or about its melting point. The granular material is inflated by being released suddenly from the state, and many inflated granular materials are collected to integrate the whole thereof. For a manufacturing method, superheated steam is supplied from respective steam tubes 14, 18, and the water- containing biodegradable resin granular material P reaches a conveyor 13 from a hopper 16 via rotary valves 15a, 15b. Its water content is fallen to an exhaust opening 12 under an enclosed state because of a high temperature pressurized condition, and reaches a hermetically sealed space 19 between rotary valves 17a, 17b. When the hermetically sealed space 19 is released, the granular material is suddenly exposed to atmospheric pressure, and foamed by evaporation of the steam in the granular material.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable resin that has recently been in the spotlight as being environmentally friendly and environmentally friendly, and more particularly to a foaming and shaping technique for them.

[0002]

BACKGROUND OF THE INVENTION Since synthetic resins are excellent in mass productivity, moldability and durability, they have achieved technological development and accompanying consumption expansion at a remarkable rate in this century. However, since the amount of these synthetic resins discarded has become enormous, many synthetic resin products are also present in the dust that floats on the sea and rushes to the coastline. At the refuse incineration plant, various problems have come to be raised due to the waste of synthetic resin. That is, since the synthetic resin has a very strong intermolecular bonding force, it emits high heat during incineration to damage the furnace wall, and the combustion gas contains a large amount of harmful gas. In addition, it does not rust even if it is exposed, and it does not decompose with light or ozone, and there is no choice but to wait for it to be abraded by mechanical energy such as wind and rain and waves.
In particular, in the case of highly foamed packaging cushioning materials, heat insulating materials, packaging trays, etc., this requires only a large volume, and separate collection is not cost-effective, so that it may occur at sea or on the coastline. Was an embarrassing entity, as it was white in color.

Under such circumstances, a recycling movement has been carried out, and degradable resins have been put on the market, and technical development of degradable resins has been remarkable recently.
Consumption is also expanding. However, degradable resin,
Biodegradable resins, in particular, are difficult to foam high with conventional chemical foaming agents because of the relationship between the softening point or melting point and the foaming temperature of the foaming agent. Foaming and shaping technology is required.

[0004]

[Technical Items Attempted to Develop] Therefore, the present invention intends to provide a molding technique capable of coping with high foaming of a biodegradable resin without requiring a special chemical foaming agent.

[0005]

[Constitution of the invention]

[Means for Achieving the Object] That is, a method for producing a degradable cushioning material according to a first invention of the present application is to bring particles of water-containing biodegradable resin into contact with steam under pressure to form the particles. A step of raising the temperature to about its softening point or melting point, a step of rapidly releasing the heated and pressurized state to expand the granules, and a large number of the expanded particles thus obtained are aggregated to integrate the whole. And a process.

Further, in the method for producing a degradable cushioning material according to the second invention of the present application, the granules of the biodegradable resin containing water are contacted with water vapor under pressure in a continuous porous mold. Then, the step of raising the temperature of the granules to the softening point or the melting point thereof is performed, and the granules are rapidly released from the heating and pressurizing state while the granules are placed in the molding die, and the granules are placed in the molding die. And inflating, and integrally forming the shape into the inner shape of the molding die.

Further, in the method for producing a degradable cushioning material according to the third invention of the present application, substantially water and a biodegradable resin are put into a cylindrical container having a constriction opening at the front to biodegrade. Of pushing the flexible resin to the front narrowing opening while heating it up to its softening point or melting point and extruding it in a fluid state from the narrowing opening to the outside of the cylindrical container, and rapidly heating and pressurizing the inside of the cylindrical container. And a step of collecting a plurality of expanded extrudates that have been released and expanded to integrate the whole. These inventions are intended to achieve the above object.

[0008]

According to the present invention, when the biodegradable resin is heated to about its softening point or melting point, the water present at the same time is heated and pressurized so that it is heated to about its softening point or melting point. It exists in a state of being forcibly confined in a biodegradable resin. Therefore, when it is rapidly released from the heating and pressurizing state, the water trapped inside expands and expands at once, so if the biodegradable resin is a granule, it will be expanded as an expanded granule. If it is extruded as a fluid, it is obtained as a puffed extrudate. The expanded granules thus obtained or the expanded extrudates appropriately subdivided and the like are aggregated together with an adhesive component or the like if necessary, and the whole is pressed or heated to bond their mutual contact parts, Are entangled with each other, or the outermost contour is solidified and enclosed, thereby giving a specific shape that is integrated as a whole. Further, if the process of obtaining the expanded granules is performed in a continuous porous mold, or if a plurality of expanded extrudates extruded in the form of a fluid are collected immediately after that, foaming due to expansion occurs. Almost at the same time, the whole is given a specific shape.

[0009]

EXAMPLES The present invention will be described below with reference to biodegradable resin and its swelling, which are its constituents, and then the method of Examples will be specifically described by using each apparatus shown in the drawings. The biodegradable resin in the present invention means a resin material whose physical properties are deteriorated based on a biological action, and a type in which the resin itself is completely decomposed and a resin which is difficult to decompose are blended to impart disintegration property. There is a type. The former type includes products produced by microorganisms, products using natural polymers, products produced from petroleum-based raw materials, and the latter type includes blends with starch and blends with aliphatic polyesters. Etc. As the biodegradation mechanism, there are various modes such as degradation by enzymes such as lipase, amylase, cellulase and protease, degradation by microorganisms such as activated sludge, and degradation by soil in natural environments such as forests and cultivated land. More specifically, polyhydroxybutyric acid and its derivatives, pullulan, cellulose-chitosan mixtures, esterification products of cellulose, amylose and wood flour, polyester-nylon copolymers, polyester copolymers, blends of starch and polyethylene. In addition to the body, polyvinyl alcohol, polyether, polyurethane, polyamide and the like can be mentioned. These generally have a low melting point and are accelerated in the presence of water. On the other hand, swelling means
It is known as a technique in the manufacture of so-called snacks such as popcorn, and in the case of snacks, grains that have an appropriate amount of water are used, and the product temperature is sufficiently raised in a high-temperature and high-pressure container. When it is suddenly released to a low pressure after holding it for a while, the moisture in the grain tissue causes instantaneous evaporation, and the tissue expands due to the expanding pressure of steam at that time, batch puff gun, belt conveyor type, It is performed by various types of devices such as a fluidized bed type. In the present invention, this technique is applied as a foaming technique for biodegradable resin.

Further, in this embodiment, pellets of Mater-Bi "Matterby" (registered trademark) sold by Nippon Synthetic Chemical Industry Co., Ltd. were used as the biodegradable resin. NOV belonging to group
In relation to the development of AMONT, it is considered as a thermoplastic biodegradable polymer in which derivative products from multiple agricultural products such as starch and modified polyvinyl alcohol sneak into each other at the molecular level and are linked by hydrogen bonds. Is what Further, it is said that biodegradation is promoted by absorbing water and swelling, and exhibits biodegradability equivalent to that of paper in an environment in which microorganisms survive.

In this embodiment, a pretreatment step of positively containing water in the granules of the biodegradable resin was provided. Specifically, after soaking the biodegradable resin granules in a container poured with sufficient water for a certain period of time, take out the hydrous biodegradable resin granules and remove water droplets adhering to the surface. The following steps were performed. The pretreatment process is
It may be soaked in hot water that is appropriately heated or boiled for a certain time, or may be left for a long time in a controlled high humidity atmosphere. By providing such a pretreatment step, more uniform water than the equilibrium water content in the atmosphere can be included in the biodegradable resin granules, so that more stable and high foaming can be achieved. it can.
Of course, even if the biodegradable resin has an equilibrium moisture content in the atmosphere depending on the heating and pressurizing conditions, depending on the required expansion ratio or the heating and pressurizing method, it is not necessary to provide this pretreatment step. The biodegradable resin which is left in the air and contains the equilibrium moisture may be used as it is.

FIG. 1 shows an example of an apparatus for carrying out the method for producing a degradable cushioning material according to the first invention of the present application, in which granules of biodegradable resin can be continuously expanded and discharged sequentially. It is like this. That is, in FIG. 1, 10 has an inlet 11 and an outlet 12, and the inlet 11 and the outlet 1
2 is a heating container having a horizontally long pressure resistant structure whose inside is a closed space by a valve mechanism provided in each of the heating cans 1 and 2.
Inside the 0, a conveyor 13 made of a mesh belt is installed over the length thereof. A steam pipe 14 from a steam generator (not shown) is provided between the forward surface 13a and the backward surface 13b of the mesh belt of the conveyor 13,
A large number of fumaroles 14a are bored in the steam pipe 14, and each fumarole 14a is directed to the outward surface 13a of the conveyor 13. In addition, a rotary valve 15a is provided in upper and lower two stages as a valve mechanism for ensuring the airtightness in the heating can 10 at each of the inlet 11 and the outlet 12.
15b, 17a and 17b are connected to each other, a hopper 16 is provided above the rotary valve 15a at the upper stage of the inlet 11, and a closed space 19 between the upper and lower rotary valves 17a and 17b at the outlet is further provided. In addition, a separate steam pipe 18 is extended so that steam having a higher temperature and pressure than the steam supplied into the heating can 10 can be appropriately supplied to the closed space 19.

Therefore, such a conveyor type expansion device A
First, superheated steam was supplied from each of the steam pipes 14 and 18 to preheat the closed space 19 between the heating can 10 and the outlet rotary valve, and then the biodegradability that was appropriately hydrated by the above pretreatment step. When the resin particles P are supplied to the hopper 16, the rotary valves 15a and 15b therebelow are sequentially transferred, and the biodegradable resin particles P reach the start end of the conveyor 13 in the heating can 10. The biodegradable resin granules P that have reached the conveyor 13 are being sent forward as the conveyor 13 advances, but since the heating can 10 is filled with superheated steam and is under high temperature pressure, By the time it is delivered to the end of 13, it is heated to its softening point or melting point. At this time, the water content of the biodegradable resin granules P is also heated at the same time.
Since the atmosphere is under high temperature and pressure, the biodegradable resin particles are forcibly confined without being evaporated from the biodegradable resin particles. The biodegradable resin granules P sent to the end of the conveyor 13 drop to the discharge port 12 immediately below as the conveyor 13 rotates, and from the rotary valve 17a at the upper stage of the discharge port to the lower stage as the valve continues to rotate. Closed space 19 with rotary valve 17b
Leading to. In preparation for the biodegradable resin particles P remaining on the mesh belt of the conveyor 13 in the vicinity of the dropping position of the biodegradable resin particles at the end of the conveyor, particularly strongly heated steam from the inside of the conveyor. May be blown off and blown off, or a rotary brush may be provided directly above and scraped off.

If necessary, a superheated steam higher than that in the heating can 10 is supplied to the closed space 19 between the upper rotary valve 17a and the lower rotary valve 17b, so that the heating and pressurizing action necessary for expansion is achieved. Eventually adjusted. The lower rotary valve 17b rotates,
When the closed space 19 is opened, the particles of the biodegradable resin are rapidly exposed to the atmospheric pressure, so that the water confined in the particles of the biodegradable resin is instantaneously evaporated. Wake up. At this time, since the particles of the biodegradable resin itself have been raised to the softening point or the melting point thereof, the force of expansion of the steam acts as a force to expand the particles of the biodegradable resin, and Foaming occurs as a swelling phenomenon in the resin particles. When the steam expands and its release occurs, the temperature of the product decreases, and in the substantially expanded state, the shape is solidified and the expansion is completed. At this time, since the degree of heat and pressure applied to the granules of the biodegradable resin and the degree of water content as a pretreatment step thereof have a great influence on the degree of expansion, it is necessary to set conditions according to the physical properties and grade of the biodegradable resin. If these conditions are not met, the degree of expansion will be insufficient, or conversely, the degree of expansion will be too large to cause rupture, or even if sufficient expansion will occur, contraction will occur thereafter.

In the expanded granules R thus obtained, the respective granules are expanded in an independent state, and after cooling and drying if necessary, for example, the molding die 2 shown in FIG.
A large number of pieces are assembled in 0 and the whole is integrated. It is desirable that the heating can and the valve mechanism be kept adiabatic and / or heated from the surroundings with high-temperature fluid, etc., and that the bottom of the heating can is provided with a detailed structure such as a discharge pipe for discharging condensed water generated. It Although the rotary valve shown in the figure is designed to rotate a simple four-blade blade, the rotor shape was devised so that a high-speed jet for preventing adhesion could be blown onto it, or a rotary piston type rotary Holding the pocket with the shaft in between, the bottom of the pocket has a piston structure and is connected to each other, when one bottom is lowered, one bottom is raised and when the raw material is received in synchronization with the rotation of the rotor May have a structure in which the bottom is lowered and rises when discharged.

In FIG. 2, the expanded granules R of the biodegradable resin obtained through the above steps are placed in the mold 20 in an appropriate amount determined in consideration of the expected filling rate. In this molding die 20, an upper die 20a and a lower die 20b have guide pins 21.
And is vertically movable, and is closed to form a space 22 having a thick-walled cross section inside. Further, the upper mold 20a and the lower mold 20b are provided with heating means, in the illustrated embodiment, a heater 23, so that the expanded granules R can be heated. The entire molding die 20 is installed between a base and a pressure plate in a press machine (not shown). In this example, the heating means was arranged in the molding die, but when the vulcanizing press machine is used as the pressing machine, the heating means itself is provided,
It suffices to use a mold having good thermal conductivity.

Therefore, the heater 23 of the molding die 20 is energized in advance, or the expanded granules R are placed in the molding die 20 and then energized to raise the temperature of the molding die 20 to expand the expanded granules R.
The temperature of the softening point or near the melting point of the mold, the mold 20 is pressed by the press machine to form the mold 2.
When 0 is closed, the expanded granules R in the inside are crushed and interlock with each other, and some of them are fused with each other. The adjacent expanded granules R are fused firmly to each other, and the outer contour becomes a single molded product shaped into the inner shape of the molding die 20. Furthermore, after the heating and pressurizing state is maintained for a while to ensure fusion inside and the like, the pressing by the press is stopped, the molding die 20 is opened, and the molded product is taken out to expand. The aggregate of particles can be obtained as a thick angle rod. At this time, heating may be interrupted during pressurization or positive cooling may be performed in order to ensure internal fusion or the like.

The angle rod, which is an aggregate molded product of expanded particles of biodegradable resin thus obtained, can be used, for example, as a corner support material for a package in a cardboard box for packaging. Even if it is illegally dumped, it will biodegrade, so even if it floats on the sea or hits the coastline, it will be decomposed after a while, and even if it is left on the ground it will wind and rain and underground. Since it absorbs the moisture of the product and decomposes it, there is no need to dispose of it at a refuse incineration plant. Moreover, it can be obtained as a comparatively high foaming product and does not require a special chemical foaming agent.

In the step of integrating the above,
If the degree of heating to the mold exceeds the melting point of the biodegradable resin, the meaning obtained as the expanded particles before that is lost, so add expanded particles of biodegradable resin with a low melting point separately. Alternatively, a degradable resin powder having a low melting point, a thermoplastic resin, and a component having an adhesive function such as glue may be added. Other adhesive components include starch paste,
Furinori, gum arabic, glue, casein, linseed oil,
Starch derivatives such as starch acetate and carboxymethyl starch, fibrin derivatives such as methyl cellulose and ethyl cellulose, sodium alginate, locust bean gum,
Vinyl-based synthetic glue such as polyvinyl alcohol, vinyl-acetate-acrylic acid copolymer-based vinyl-based copolymer synthetic glue, sodium polyacrylate-based acrylic synthetic glue, styrene-maleic acid copolymer-based styrene-based synthetic glue, etc. In addition to natural adhesives, semi-synthetic adhesives, synthetic adhesives, adhesives, as well as solutions in which various resins are appropriately dissolved in a solvent, thermoplastic resins, powders of decomposable resins having a low melting point, and the like can be used. Further, it may be adhered and adhered by an adhesive elastomer such as silicone gel or urethane gel. If a natural product or biodegradable adhesive component is used as this adhesive component, a completely pollution-free degradable cushioning material can be obtained. Also, of course, one of heating and pressurization may be applied, and the expanded granules may be adhered to each other, mechanically entangled with each other, or the outermost shell may be solidified and confined to be integrated. It suffices to exhibit a specific overall shape that has been converted.

In the above embodiment, the particles of the biodegradable resin were expanded in an independent state, and subsequently, in the next step, a large number of aggregates were formed to shape the whole shape. An embodiment of the method for producing a degradable cushioning material according to the second invention of the present application, which enables the step of integrating the above-mentioned steps to be performed almost simultaneously, will be described. FIG. 3 shows an example of an apparatus for carrying out this method.
Is a heating can, and this heating can 30 includes an upper can part 30a and a lower can part 3
0b can be opened and closed by a hinge 30c and the rims are in close contact with each other to form a closed space 31 having a pressure resistant structure, and a steam pipe 32 from a steam generator (not shown) is extended to the lower can portion 30b.
Further, the upper can portion 30a is provided with a quick opening lid 33 capable of withstanding sudden and extreme opening. And this heating can 30
A porous molding die 34 made of continuous porous material can be freely arranged inside, and the fumaroles of the steam pipe 32 are directed to the porous molding die 34. On the other hand, this porous mold 34
Is the upper mold 34a and the lower mold 3 similar to the molding mold 20 described above.
4b, and its flange 34c can be easily clamped by a clamping means (not shown) so that it can be integrated at a proper time. In the illustrated embodiment, a cubic space 35 is formed inside. Although not shown in the figure, it is not composed of a solid metal material, but is composed of a porous material having innumerable network-like pores that communicate the inside and the outside almost all over. As the porous material, in addition to foamed metal, a sintered material such as metal or ceramics, which is sinter-molded by adding a filler capable of forming voids, and metal wire, punching metal, or the like is press-formed. And various forms such as those formed by laminating them.

In such a batch-boil type expansion device B,
First, superheated steam is supplied from the steam pipe 32 to preheat the heating can 30 and, if possible, the porous mold 34, and then the heating can 30
And, the porous mold 34 is sequentially opened, and the granules P of the biodegradable resin that have been appropriately hydrated by the pretreatment step are placed in the porous mold 34 in an appropriate amount determined in consideration of the expected expansion ratio, Immediately, the porous mold 34 is clamped, and the porous mold 34 is placed so as to face the steam pipe 32 in the heating can 30, and the heating can 30 is closed. Then, the superheated steam is again supplied into the heating can 30. Then, the heating can 30 is filled with superheated steam and is under high-temperature pressure, but since the porous mold 34 disposed inside is made of continuous porous material, the superheated steam is not formed in the porous mold 34. The degradable resin particles P are also heated. Therefore, the biodegradable resin granules P will soon be heated to the softening point or the melting point thereof, and at the same time, the water content of the biodegradable resin granules will be heated. Since it is under pressure, it is forcibly confined in the biodegradable resin granules without evaporating from the biodegradable resin granules.

When the rapid opening lid 33 of the upper can portion is suddenly opened while observing the time when such a state is reached, the biodegradable resin granules P are stored in the continuous porous molding die 34. However, since it is suddenly exposed to the atmospheric pressure, expansion occurs in the porous mold 34. Since this expansion is within the porous mold 34 whose outermost contour is restricted, the biodegradable resin particles are restricted in their expansion during expansion.
In a state where they influence each other, they expand so as to fill each other's space, and expand in a state where the inside of the porous molding die 34 is uniformly filled, and the overall shape is the same as the inner shape of the porous molding die 34. Will be shaped. For this reason, if the pores of the porous molding die are relatively large, there is an advantage that heating and pressurizing and exposure to low pressure can be performed rapidly, but the surface after expansion is strongly uneven due to the pores. Tend to get out. In such a case, thereafter, the surface can be simply pressed or heated by a solid molding die to make the surface smooth. Therefore, it is desirable that the pores are small as long as the flow resistance of water vapor is not significantly increased.

Thereafter, the heating can 30 is opened to take out the perforated mold 34, and after appropriately cooling, the clamp is released and taken out, and then the perforated mold 34 is cooled and dried appropriately to obtain the inner shape of the perforated mold 34. A cubic shaped puffed molded article is obtained. In this expanded molded product, the expanded particles constituting the expanded molded product are complicatedly intruded into one body, and can be used as various cushioning materials and the like as in the above-mentioned embodiment. In addition, in order to withstand a heavy load, the adhesive components and the like may be impregnated and strengthened to bond the expanded tissues.

Next, an embodiment of the method for producing the degradable cushioning material according to the third invention of the present application will be described. In each of the above-mentioned examples, the particles of the biodegradable resin are designed to be swelled independently even though the outermost shell is regulated, but in this example, the biodegradable resin particles are There is no division as a body and the whole is in a fluid state and is sequentially expanded by extrusion molding, and a degradable cushioning material is produced through a process of obtaining a continuous expanded extrudate. That is, FIG. 4 shows a device therefor, in which 40 is a cylinder, a hopper 41 is provided above the start end thereof, and a die 42 is provided at the end end thereof, and the interiors of these are communicated and the inside of the cylinder is provided with a tip. The taper wall 40a is formed so as to narrow as it goes to. The screw 4 is placed in the cylinder 40.
3 is provided in the vicinity of the tapered wall 40a, and a heater 44 for heating is arranged around the cylinder 40.

In such an extrusion type expansion device C, if the hopper 41 is supplied with the granules P of the biodegradable resin which has been hydrated as in the above-mentioned embodiment, the biodegradable resin charged in the cylinder 40 is discharged. The granules P may be narrowed as the inside of the cylinder 40 moves forward while being pushed forward in the cylinder 40 by the screw 43. Therefore, the shearing force at the time of pushing and the inner wall of the cylinder 40 by the heater 44 are formed. Is heated to about the softening point or melting point,
At least immediately before the die 42, it becomes fluid and is extruded as fluid from the die 42. At this time, the inside of the cylinder 40 is continuously supplied with biodegradable resin particles from the rear side, and the extrusion to the front side is restricted by the die 42 and the tapered wall 40a. The water contained in the particles of the biodegradable resin is forcibly confined and pushed into the biodegradable resin without being evaporated from the particles of the biodegradable resin. Therefore, at the moment when the biodegradable resin is extruded in a fluid state from the die 42, the biodegradable resin that has been heated and pressurized until now is suddenly exposed to the atmospheric pressure, so that the biodegradable resin is forcibly trapped. Moisture causes evaporation instantaneously. At this time, the biodegradable resin is extruded one after another in the form of a cross-section die 42 in a fluid state, so that a continuous rod-shaped material is obtained in which its cross-sectional area expands due to the force of expansion of water vapor. In the present embodiment, the rotary cutter 45 at the tip of the die 42 is operated in a timing manner to cut the continuous rod-shaped object into a fixed length to obtain a large number of expanded extrudates S having an appropriate length.
The puffed extrudate S thus obtained may be further crushed to an appropriate size and filled in the forming die 20 in FIG. Making use of the extruded shape of the extruded product S, for example, a rectangular flat molding die 5 with an edge as shown in FIG.
It is possible to align these in 0 and integrate them as a whole to form a sheet. Also in this case, as in the case of the above-mentioned example, heating or pressurization is appropriately performed, a puffed extrudate of a biodegradable resin having a low melting point is added separately, and powders of a degradable resin having a low melting point, various adhesives such as a thermoplastic resin are used. Needless to say, the components may be added.

Further, for example, as shown in FIG. 6, the cylinder 4
0 is provided with a plurality of dies, and a second die is further provided in front of the die to regulate the outer contour of the entire die, and one die is inflated by the first die 61 and is being inflated by the second die 62 It is also possible to obtain a puffed extrudate having a thick shape or an appropriate cross-sectional shape by integrating them as a whole.
At this time, the adhesive component may be sprayed on the tip of the first die 61, or the second die 62 may be provided with a heating or cooling means. In the embodiment using the apparatus of FIGS. 5 and 6, the biodegradable resin granules containing water are supplied to supply the biodegradable resin and the water into the cylinder, but the present invention is not limited to this. Since it is sufficient that the biodegradable resin contains water under pressure when it is extruded from the final die, biodegradation from the hopper is not required without using granules of the biodegradable resin that has been hydrated as a pretreatment step. The biodegradable resin and the water may be substantially supplied by adding and supplying the water together with the functional resin.

Further, although not shown, depending on the type of biodegradable resin, for example, the granules of the biodegradable resin are put in a rotary heating can having a horizontal rotating shaft, and the lid is sealed and rotary heated. While rotating the can, it is externally heated by an appropriate heating means such as a gas burner, and the pressure inside the rotary heating can is raised to high pressure by the water contained in the biodegradable resin or the added water, and the lid is rapidly opened to obtain expanded granules. You may do it. However, in this case, it is difficult to rapidly heat the biodegradable resin into the granules, and the water is forcibly confined in the granules of the biodegradable resin without being evaporated from the granules of the biodegradable resin. ,
Since it is quite difficult to raise the temperature to the softening point or the melting point of the biodegradable resin, it is difficult to control the swelling action. This is because one of the causes is the difference between heating and pressurizing with superheated steam or heating and pressurizing with saturated steam, and in this respect, each embodiment using the apparatus shown in the drawings supplies superheated steam. It is heated and pressurized,
That is far more advantageous.

In addition to the above-mentioned respective examples, the obtained expanded granules or expanded extrudates are once dipped in a component such as an adhesive component capable of forming a solidified film to such an extent that they are not impregnated into the inside, and then dried. After forming a skin layer on the surface, a large number of them may be aggregated and integrated, or a skin layer may be formed in the same manner on the integrated product, and further, a film pack may be formed along their outer shape. For example, if the inside is sealed, a buffer effect due to the air layer trapped inside can be expected. Separately from this, as a post-treatment step, a water-repellent or water-resistant paint such as a silicone-based paint or a colored paint is applied, and an insect repellent or an insecticide component or the like is applied to these paints or any of the above steps. May be added. Of course, the pre-treatment process and these post-treatment processes are not always necessary and can be appropriately added. In the above examples, the biodegradable resin used was Mater-Bi "Matterby" (registered trademark) in the form of pellets, but the present invention is not limited thereto and other biodegradable resins are used. However, biodegradable resins of various sizes and shapes can be applied.

Therefore, the degradable cushioning material according to the present invention is shaped as in each of the above-mentioned embodiments, is shaped like a tray, and is used as a cushioning material for pottery, glassware, precision equipment, high-grade fruits and the like. By shaping it into a shape, it can be used in the same manner as in the case where a conventional foam such as Styrofoam is used. Further, rather than being used as a cushioning material, it is naturally possible to deal with usage such as a heat insulating material. In this sense, the degradable cushioning material referred to in the present application is intended only for strict cushioning. Not only the above-mentioned applications, but also a wide range of applications and products applicable as highly foamed products.

[0030]

As described above, according to the present invention, the biodegradable resin can cope with high foaming without requiring a special chemical foaming agent, and can be foamed and shaped into an appropriate shape. It can be provided as a substitute for the foam of the present invention and can contribute to the reduction of garbage pollution, which is now an important issue.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a conveyor-type expansion device which is an example of a device for carrying out an embodiment of the method for producing a biodegradable cushioning material of the present invention.

FIG. 2 is a schematic vertical cross-sectional view showing a state in which a large number of expanded particles in an embodiment of the method for producing a biodegradable cushioning material of the present invention are aggregated in a molding die and integrated as a whole.

FIG. 3 is a schematic vertical cross-sectional view of a batch cauldron expansion device which is an example of a device for carrying out another embodiment of the method for producing a biodegradable cushioning material of the present invention.

FIG. 4 is a schematic vertical cross-sectional view of an extrusion-type expansion device which is an example of a device for carrying out still another embodiment of the method for producing a biodegradable cushioning material of the present invention.

FIG. 5 is a perspective view showing a state where a large number of expanded extrudates in a further embodiment of the method for producing a biodegradable cushioning material of the present invention are aligned in a molding die and integrated as a whole.

FIG. 6 is a perspective view of essential parts near a die in an example of an apparatus for carrying out still another embodiment of the method for producing a biodegradable cushioning material of the present invention.

[Explanation of symbols]

 A Conveyor type expansion device B Batch kettle type expansion device C Extrusion type expansion device P Granules of hydrolyzable biodegradable resin R Expanded granules S Expanded extrudate 10 Heating can 11 Inlet port 12 Conveyor 13a Forward surface 13b Return surface 14 Steam pipe 14a Vent hole 15a Rotary valve at inlet 15b Rotary valve at inlet 16 Hopper 17a Rotary valve at outlet 17b Rotary valve at outlet 18 Steam pipe 19 Sealed space 20 Mold 20a Upper die 20b Lower Mold 21 Guide pin 22 Thick angled space 23 Heater 30 Heating can 30a Upper can part 30b Lower can part 30c Hinge 31 Closed space 32 Steam pipe 33 Quick open lid 34 Porous mold 34a Upper mold 34b Lower mold 34c Flange 35 Cubic Space 40 Cylinder 40a Tapered wall 41 Hot Over 42 die 43 Screw 44 Heating 45 rotary cutter 50 bordered rectangle flat mold 61 first die 62 second die

Claims (3)

[Claims] 1. A step of bringing a granule of hydrous biodegradable resin into contact with water vapor under pressure to raise the granule to its softening point or melting point, and then rapidly from the heat and pressure state. A method for producing a degradable cushioning material, which comprises a step of releasing and expanding the granules, and a step of collecting a large number of the expanded granules thus obtained to integrate the whole. 2. A step of bringing particles of hydrous biodegradable resin into contact with water vapor in a continuous porous mold under pressure to raise the particles to a softening point or a melting point thereof. A step of rapidly releasing the heating and pressurizing state of the granules while the granules are placed in the molding die to expand the granules in the molding die and integrally form the whole into the inner shape of the molding die. A method for producing a degradable cushioning material, comprising: 3. A water-degradable resin and a water-degradable resin are substantially put into a cylindrical container having a narrowed opening in the front, and while the biodegradable resin is pushed to the front narrowed opening, its softening point or melting point is reached. The process of extruding from the constriction opening to the outside of the cylindrical container by raising the temperature to a fluidized state, and gathering a plurality of expanded extrudates that are rapidly released from the heated and pressurized state in the cylindrical container and integrate the whole A method for producing a degradable cushioning material, comprising the steps of: