JPH05269875A - Method for molding biodegradable resin - Google Patents

Abstract

PURPOSE:To provide molding technique highly foaming biodegradable resin without requiring a special chemical foaming agent. CONSTITUTION:A process bringing particles 1 of a moisture-containing biodegradable resin into contact with oil 5 heated to the b.p. of water or higher to boil and evaporate the moisture in the biodegradable resin and a process gathering the obtained foamed particles of the biodegradable resin and heating and/or pressing the whole of the particles to integrate the same are provided. The moisture in the biodegradable resin receives the heat of the peripheral oil to be boiled and evaporated while the biodegradable resin itself is softened or melted by the peripheral oil to be foamed by the steam pressure obtained by the boiling and evaporation of the moisture in the resin. A large number of these foamed particles are gathered to be pressed under heating and fused or bonded each other or mechanically entangled and confined in the outermost solidified and shaped skin to obtain an integrated specific whole shape.

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. Various problems have also been raised in waste incineration plants due to synthetic resin waste. 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, as for the cushioning material for packing, the heat insulating material, the packaging tray, etc., which are molded with high foaming, it requires only a large volume and the separate collection does not justify the cost. 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. With respect to degradable resins, technological development is remarkable and consumption is gradually expanding. There is a tendency. However, degradable resins, especially biodegradable resins, are difficult to be highly foamed by conventional chemical foaming agents because of the relationship between their softening or melting points and the foaming temperature of the foaming agents, and now, especially High foaming and shaping technology of degradable resin 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, the method for molding a biodegradable resin, which is the first invention of the present application, comprises contacting hydrous granules of biodegradable resin with oil heated above the boiling point of water, After boil vaporizing in a biodegradable resin, and after collecting a large number of foam particles of the biodegradable resin obtained by this,
A step of heating and / or pressurizing the whole to integrate them. Further, the method of molding the biodegradable resin according to the second invention of the present application, the granules of hydrous biodegradable resin is contacted with oil heated above the boiling point of water,
A step of boiling and evaporating water-containing water in a biodegradable resin, and a large number of biodegradable resin foam granules thus obtained are collected together with an adhesive component, and the whole is heated and / or pressurized to be integrated. And a step of setting.
These inventions are intended to achieve the above object.

[0006]

In the present invention, the water-containing water in the biodegradable resin receives the heat of the surrounding oil and evaporates by boiling. On the other hand, since the biodegradable resin itself is softened or melted by the surrounding oil, it expands or foams due to the vapor pressure of the vaporized inside. Then, a large number of the foamed granules thus obtained are aggregated together with an adhesive component if necessary, and if the whole is heated and / or pressurized, their mutual contact portions are fused or bonded, or mechanically. It becomes entangled, or the outermost contour is solidified and enclosed, so that it has an integrated specific overall shape.

[0007]

EXAMPLES The present invention will be described below with reference to biodegradable resins as its constituent elements, and then concretely based on the illustrated examples. 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. And
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. is there. 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 mixture, esterification products of cellulose, amylose and wood flour, polyester-nylon copolymer, polyester copolymer, blend 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.
Further, the oil heated above the boiling point of water may be various ones such as animal oil, vegetable oil, mineral oil, chemically synthesized oil, etc., but it has high safety and low viscosity, and is separated and recovered later. Easy ones are suitable.

In this example, the biodegradable resin was used as Mater-Bi "Matterby" sold by Nippon Synthetic Chemical Industry Co., Ltd.
(Registered trademark) pellets were used, and the commercially available edible salad oil was used as the oil. Here, Mater-Bi as a biodegradable resin is involved in the development of NOVAMONT, which belongs to the Montedison Group of Italy, and a purified substance from a plant and a synthetic polymer dip into each other at the molecular level, It is a thermoplastic biodegradable polymer formed by hydrogen bonds. Further, its melting point is around 140 ° C., and it is said that biodegradation is promoted by absorbing water and swelling, and exhibits biodegradability equivalent to that of paper under the environment of microbial survival.

In this embodiment, a water-containing step of positively containing water in this biodegradable resin was provided as a pretreatment step. Specifically, as shown in FIG. 1, sufficient water 3 was poured into the container 2, and the pelletized biodegradable resin 1 was immersed in the water for 10 hours. Although not shown, after this, the hydrolyzed biodegradable resin was taken out and spread on a water-absorbent paper to remove water droplets adhering to the surface, which was the pretreatment for the next step. In addition to this, the water-containing step may be immersed in hot water that is appropriately heated or boiled, or may be left for a long time in a high humidity atmosphere. By providing such a water-containing step, more water can be contained than the equilibrium water content in the atmosphere, so that the foaming can be further increased.
Further, according to the water-containing step which is sufficiently calculated and controlled, it is easy to obtain the one in which the biodegradable resin has a uniform water content in the skin layer and the core portion and is uniformly foamed. Of course, if the equilibrium water content is necessary and sufficient for the required expansion ratio, the biodegradable resin containing the equilibrium water content that is left in the atmosphere may be used as it is without needing to provide a water-containing step.

In the subsequent step of contacting with oil heated above the boiling point of water, which is a feature of the present invention, the pot 4 is filled under atmospheric pressure of ordinary temperature and humidity in this embodiment as shown in FIG. Salad oil 5 with a gas stove 6 at 130 ℃ -1
It was heated to about 80 ° C., and the water-containing biodegradable resin 1 obtained through the water-containing step was dispersed and dropped in this salad oil 5 in the form of pellets.

Oil 5 obtained by heating biodegradable resin 1 containing water
When immersed, a large amount of heat of oil is transferred from the surface to the biodegradable resin, and the water content of water is heated almost simultaneously with the biodegradable resin itself, and the temperature rises rapidly.
Since this temperature increase reaches the boiling point of water or higher, the water content of water is vaporized in the biodegradable resin. Since the biodegradable resin has also reached the softening temperature or melting point at the same time, the biodegradable resin itself is expanded and foamed due to the vapor pressure of the water vaporized inside. This action is performed sequentially from the skin layer, and in the case of small grains, the whole is almost instantaneously performed almost instantaneously, but in the case of relatively large grains, it is sequentially performed from the skin layer to the core. The same action is continuously performed, and soon the whole becomes almost uniformly inflated and foamed. The biodegradable resins that are adjacent to each other in the initial stage of oil immersion may be obtained in the form of a lump that is fused and foamed with each other.

In this embodiment, the oil temperature is from 160 ° C to 1 ° C.
When the temperature is set to 80 ° C., foaming can be performed with an expansion ratio of about 8 to 10 times, which is much higher than the expansion ratio of about 2 times obtained by adding a few% of a commercially available chemical foaming agent. I was able to make it. The foamed granules of the biodegradable resin thus obtained are then subjected to centrifugation, washing, drying, etc., so that the adhered oil is desirably separated and recovered. It may be used as an oil for the process. Also, if the oil temperature in this step is low,
A comparatively low foaming type because the steam pressure due to boiling vaporization is not utilized at once because the biodegradable resin softens or melts slowly, and when the oil temperature is high, boiling vaporized steam is released all at once. A highly foamed product can be obtained.

The foamed granules 10 of the biodegradable resin thus obtained are assembled in a molding die 7 as shown in FIG. 3 and heated and pressed in the next step in this embodiment. That is, in FIG. 3, the expanded granules 10 of biodegradable resin obtained through the above steps are placed in the cavity of the molding die 7 in an appropriate amount determined in consideration of the expected filling rate.
In this molding die 7, the upper die 7a and the lower die 7b are guide pins 7
The upper mold 7a and the lower mold 7b are closed as shown by the two-dot chain line A so as to form a cavity having a thick-walled cross section inside. Is becoming Further, the upper die 7a and the lower die 7b are provided with heating means, in the illustrated embodiment, a heater 8,
The expanded granules 10 placed in the cavity can be heated. Further, the entire molding die 7 is installed between a base and a pressure plate in a press machine (not shown). In this embodiment, the heating means 8 is arranged in the molding die 7, but when a vulcanizing press is used as the pressing machine, the heating means itself is provided, so that the molding die having good thermal conductivity should be used. All you have to do is use it.

Therefore, the heater 8 of the molding die 7 is energized in advance, or the expanded granules 10 are placed in the cavity and then energized so that the temperature of the molding die 7 rises and the expanded granules 10 are heated.
The softening or heating point near the melting point, the molding die 7 is pressed by the press machine and the upper die 7a is pressed.
If the lower mold 7b and the lower mold 7b are closed, the foamed granules 1 inside
0 is partially crushed and intermingled with each other, and some of them are fused to each other, and particularly, in the portion that comes into contact with the inner wall of the molding die, the adjacent foamed granules are relatively firmly fused to each other, The outer shell becomes a single molded product shaped into a cavity. Furthermore, after maintaining the heating and pressurizing state for a while to ensure internal fusion and the like, the pressing by the pressing machine is stopped, and the upper mold 7a and the lower mold 7b are released, and If the molded product in the tee is taken out, the aggregate of the expanded granules 10 can be obtained as a thick angled rod. In addition,
At this time, in order to ensure internal fusion and the like, it is possible to appropriately suspend heating during pressurization, actively cool, or the like.

An angled rod having a thick wall, which is an aggregate molded product of the expanded beads 10 of the biodegradable resin thus obtained, is
It can be used as a corner support material for a package in a packaging cardboard box. 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 above process, if the heating degree of the mold 7 far exceeds the melting point of the biodegradable resin,
The meaning obtained as the expanded granules 10 by relatively high-foaming in the previous step is lost. To this end, as the foamed granules, foamed granules made of a biodegradable resin having a low melting point are added separately, or a powder of a degradable resin having a low melting point, a thermoplastic resin, and a component having an adhesive function such as glue. May be added.
In addition to this, as the adhesive component referred to in the present application, starch paste, furi, gum arabic, glue, casein, linseed oil, starch derivatives such as starch acetate / carboxymethyl starch, fibrin derivatives such as methyl cellulose / ethyl cellulose, sodium alginate, locust bean. Gum, vinyl synthetic adhesives such as polyvinyl alcohol, vinyl acetate synthetic adhesives such as vinyl acetate acrylic acid copolymers, acrylic synthetic adhesives such as sodium polyacrylate, styrene synthetic adhesives such as styrene-maleic acid copolymers In addition to adhesives such as glue, natural, semi-synthetic, and synthetic glues, adhesives may be used, as well as solutions in which various resins are appropriately dissolved in solvents, and solvents that soften and swell biodegradable resins may be used. By heating and pressurizing the expanded granules together with these adhesive components, the expanded granules are fused and mechanically entangled in the same manner as in the above-described example, and are also fused and bonded by the adhesive component. As a result, the whole is shaped into a specific shape.

Further, as a post-treatment step, if it is intended to endure a heavy load and have a life, a water-resistant paint or the like may be applied thereafter. In addition to the above, in the present invention, a sheet-like material is obtained between flat plate-shaped molding dies, or it is shaped into a tray, or is applied to various shapes as a cushioning material for crockery, glass products, precision instruments, high-grade fruits and the like. It can be shaped and used in the same manner as in the case where conventional foams such as Styrofoam were used. In the above examples, Mater-Bi "Matterby" (registered trademark) pellets were used as the biodegradable resin, and salad oil was used as the oil, but the present invention is not limited to these. Instead, other biodegradable resins, biodegradable resins of various sizes and shapes, and other oils can be applied. In some cases, the heated oil does not come into contact with the biodegradable resin as a liquid, but it can be applied even when the heated oil comes into contact with the biodegradable resin under a filled atmosphere. The water-containing step, the pretreatment step and the posttreatment step such as centrifugation, washing, drying, and painting are not necessarily required and can be appropriately added. In addition, when the oil is a drying fat or oil, it may be used as an adhesive component in some cases, and therefore, the oil adhering to the foam granules may be used as it is as an adhesive component without being recovered. Further, in the above-mentioned embodiment, the molding was performed batchwise by the molding die once, but when a continuous rod-shaped aggregate molding having a predetermined cross section is required, it is gradually extruded by a so-called extrusion molding in a cylindrical molding die. Alternatively, heating and / or pressure may be applied to continuously shape. Further, in the above-mentioned embodiment, the heating and the pressing are performed, but even when either one of them is made to act, the foamed granules are fused to each other, adhered, or mechanically entangled with each other. The outermost contour may be solidified and confined to present an integrated specific overall shape.

[0018]

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 perspective view showing a state of a water-containing step as a pretreatment step in an example of the method for molding a biodegradable resin of the present invention.

FIG. 2 is a perspective view showing a state of a foaming step in one example of the method for molding a biodegradable resin of the present invention.

FIG. 3 is a partial cross-sectional view of a molding die showing a state of a shaping step in one example of the method for molding a biodegradable resin of the present invention.

[Explanation of symbols]

 1 biodegradable resin 2 container 3 water 4 pan 5 oil 6 gas range 7 molding die 7a upper die 7b lower die 71 guide pin 8 heater (heating means) 10 foam granules of biodegradable resin

Claims (2)

[Claims] 1. A step of bringing water-containing biodegradable resin granules into contact with oil heated to a boiling point of water or higher to evaporate water-containing water in the biodegradable resin by boiling, and a biodegradable resin obtained thereby. A method of molding a biodegradable resin, which comprises a step of collecting a large number of the expanded granules and then heating and / or pressurizing the whole to integrate them. 2. A step of bringing hydrous biodegradable resin granules into contact with oil heated to a boiling point of water or higher to evaporate hydrous water in the biodegradable resin, and a biodegradable resin obtained thereby. And a step of assembling a large number of the foamed granules together with the adhesive component, and heating and / or pressurizing the whole to integrate them.