JP3241088B2 - Molding method of biodegradable resin - Google Patents

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 which has recently attracted much attention as an earth-friendly and environmentally-friendly one, and more particularly to a foaming and shaping technique thereof.

[0002]

BACKGROUND OF THE INVENTION Synthetic resins are excellent in mass productivity, moldability, and durability, and have undergone technical development and the accompanying increase in consumption at a phenomenal rate this century. However, the amount of these synthetic resins that have been discarded has become enormous, and many synthetic resin products have been found in garbage that floats on the sea or rushes to the shoreline. Various problems have also been raised in garbage 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 and damages the furnace wall, and the combustion gas contains a large amount of harmful gas. In addition, even if it is bare, it does not rust or decompose with light or ozone, and it has no choice but to wait for it to be scraped off by mechanical energy such as wind, rain, and waves. In particular, in the case of highly foamed materials such as cushioning material for packing, heat insulating material, and packaging trays, this requires only volume, and sorting and collection is not worth the cost. Was an annoying entity that stood out, partly because it was white.

Under these circumstances, recycling campaigns have been implemented, and degradable resins have been put on the market. Technical development has been remarkable for degradable resins, and consumption has gradually increased. There is a tendency. However, degradable resins, especially biodegradable resins, are difficult to foam with a conventional chemical blowing agent because of the relationship between the softening or melting point and the foaming temperature of the foaming agent. High foaming and shaping techniques for degradable resins are required.

[0004]

Accordingly, an object of the present invention is to provide a molding technique capable of coping with high foaming of a biodegradable resin without requiring a special chemical foaming agent.

[0005]

Configuration of the Invention

Means for Achieving the Object The first aspect of the present invention relates to a method for molding a biodegradable resin, which comprises bringing granules of a biodegradable resin into contact with an oil heated to a temperature higher than the boiling point of water. The process of boiling and vaporizing the biodegradable resin in the biodegradable resin
And integrating the whole by heating and / or pressurizing. Further, the method for molding a biodegradable resin according to the second invention according to the present application is to bring the granules of the biodegradable resin containing water into contact with oil heated to a boiling point of water or higher,
A step of boiling and evaporating water-containing water in a biodegradable resin, and after assembling a large number of foamed particles of the biodegradable resin obtained together with an adhesive component, heating and / or pressurizing the whole to integrate them. And a step of squeezing.
The present invention aims to achieve the above object.

[0006]

According to 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, the biodegradable resin expands or foams due to the vapor pressure of boiling and vaporizing inside. If necessary, a large number of the obtained expanded granules are assembled together with an adhesive component, and if the whole is heated and / or pressed, the mutual contact portions are fused or bonded, or mechanically. When they are entangled or the outermost shape is solidified and confined, they come to have an integrated specific overall shape.

[0007]

Next, the present invention will be described in detail with reference to the illustrated embodiment after describing the biodegradable resin as a constituent element thereof. The biodegradable resin in the present invention means a resin material whose physical properties are reduced based on a biological action. There is a type. And
The former type includes microbial products, natural polymer-based products, products derived from petroleum-based raw materials, etc.The latter type includes blends with starch and blends with aliphatic polyesters. is there. These biodegradation mechanisms include various aspects such as degradation by enzymes such as lipase, amylase, cellulase, and protease; degradation by microorganisms such as in activated sludge; and degradation by soil in natural environments such as forests and cultivated lands. More specifically, polyhydroxybutyric acid and its derivatives, pullulan, cellulose-chitosan mixture, esterified products of cellulose, amylose and wood flour, polyester-nylon copolymer, polyester copolymer, blend of starch and polyethylene Examples include body, polyvinyl alcohol, polyether, polyurethane, polyamide and the like. These generally have a low melting point and are accelerated in the presence of water.
The oil heated above the boiling point of water may be various oils such as animal oils, vegetable oils, mineral oils, synthetic oils, etc., but is highly safe, has low viscosity, and can be separated and recovered later. Easy ones are suitable.

[0008] In the present embodiment, the biodegradable resin is a Mater-Bi “Matterby” sold by Nippon Synthetic Chemical Industry Co., Ltd.
(Registered trademark) pellets, and a commercially available edible salad oil was used as the oil. Here, Mater-Bi as a biodegradable resin is involved in the development of NOVAMONT, a company belonging to the Montedison group of Italy, and a purified substance from a plant and a synthetic polymer penetrate into each other at the molecular level, It is a thermoplastic biodegradable polymer formed by hydrogen bonding. Further, its melting point is about 140 ° C., and it is said that it absorbs water and swells to promote biodegradation, and exhibits biodegradability equivalent to that of paper in an environment where microorganisms can survive.

In this embodiment, a water-containing step for positively containing water in the biodegradable resin is provided as a pretreatment step. Specifically, as shown in FIG. 1, a sufficient amount of water 3 was poured into a container 2, and the pellet-like biodegradable resin 1 was immersed for 10 hours in a submerged state. Although not shown, after this, the hydrated biodegradable resin was taken out, spread on water-absorbing paper, and water droplets adhering to the surface were removed to perform pretreatment in the next step. In addition, this water-containing step may be immersed in appropriately heated or boiling water or may be left in a high-humidity atmosphere for a long time. By providing such a water-containing step, it is possible to contain more water than the equilibrium moisture in the atmosphere, so that it is possible to achieve a higher foaming.
In addition, according to the well-calculated and controlled water-containing step, it is easy to obtain a foamed biodegradable resin having a uniform water content in the skin layer and the core and having a uniform foam. Of course, if the equilibrium moisture is necessary and sufficient for the required expansion ratio, a biodegradable resin containing equilibrium moisture may be used as it is left in the atmosphere without dare 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 as shown in FIG. 130 ° C ~ 1 in salad oil 5 with gas range 6
Heating was performed to about 80 ° C., and the water-containing biodegradable resin 1 obtained through the water-containing step was dispersed and dropped in the salad oil 5 in the form of pellets.

The biodegradable resin 1 containing water is heated oil 5
When the biodegradable resin is immersed, a large amount of heat of oil is transmitted to the biodegradable resin from its surface, and the water content of the biodegradable resin is heated almost simultaneously with the biodegradable resin itself and the temperature rises rapidly.
Since this temperature rise reaches the boiling point of water or more, the water-containing moisture is boiled and vaporized in the biodegradable resin. Since the biodegradable resin also reaches the softening temperature or the melting point at the same time, the biodegradable resin itself expands and foams due to the steam pressure that has been vaporized inside. This action is carried out sequentially from the skin layer. In the case of small grains, the whole is performed almost instantaneously and almost instantaneously, but in the case of relatively large grains, the action is successively performed from the skin layer toward the core. The same operation is performed continuously, and soon the whole becomes almost uniformly expanded and foamed. The biodegradable resins adjacent to each other in the initial stage of the oil immersion may be obtained as a cluster-like mass which is fused together and foamed.

In this embodiment, the temperature of the oil is from 160 ° C to 1 ° C.
At 80 ° C., it can be foamed with a foaming ratio of about 8 to 10 times, which is much higher than the foaming ratio of about 2 times obtained by adding a few percent of a commercially available chemical foaming agent. Was able to be transformed. The foamed particles of the biodegradable resin thus obtained are preferably subjected to centrifugal separation, washing, drying, etc., so that the adhered oil is preferably separated and collected. It may be used as a process oil. Also, if the oil temperature in this step is low,
Compared to those with relatively low foaming because the steam pressure by boiling vaporization is not used at a stretch because the biodegradable resin slowly reaches the softening or melting point. A highly foamed product can be obtained.

In the present embodiment, the foamed particles 10 of the biodegradable resin thus obtained are assembled in a molding die 7 as shown in FIG. 3 as a next step, and heated and pressed. That is, in FIG. 3, an appropriate amount of the foamed biodegradable resin particles 10 obtained through the above-described process is set in the cavity of the mold 7 in consideration of a predetermined filling rate.
The molding die 7 includes an upper die 7a and a lower die 7b that
The upper die 7a and the lower die 7b are closed as shown by a two-dot chain line A so as to form a cavity having a thick section in the inside as shown by a two-dot chain line A. Has become. The upper mold 7a and the lower mold 7b are provided with heating means, in the illustrated embodiment, a heater 8.
Thus, the expanded granular material 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 (not shown). In this embodiment, the heating means 8 is arranged in the molding die 7. However, when a vulcanizing press is used as the press, the heating means itself is provided. You only have to use it.

Therefore, the heater 8 of the mold 7 is energized in advance, or the foam granules 10 are placed in the cavity and energized.
At a time when the temperature is raised to a temperature close to its softening or melting point, the molding die 7 is pressed by a press machine, and the upper die 7a is pressed.
And the lower mold 7b are closed so that the internal foamed granules 1
0 is partially crushed and interlocks with each other, and partially fuses with each other. In particular, at a portion in contact with the inner wall of the mold, adjacent foam particles fuse relatively firmly along the same, The outer shell becomes a single molded product formed into a cavity shape. Furthermore, after maintaining the state of heating and pressurizing for a while to ensure the internal fusion and the like, the pressing by the press machine is stopped, the upper mold 7a and the lower mold 7b are released, and the cabinet is released. If the molded product in the tee is taken out, the aggregate of the expanded granules 10 can be obtained as a thick angle rod. In addition,
At this time, in order to ensure the internal fusion or the like, it is possible to appropriately interrupt the heating during the pressurization, or actively cool the glass.

The thick angled rod, which is an aggregate molded product of the expanded biodegradable resin particles 10 obtained as described above,
It can be used as a corner support for a packing item in a packing cardboard box. This is because biodegradation occurs even in the case of illegal dumping. Since it decomposes by absorbing moisture, there is no need to dispose of it at a garbage incineration plant. Moreover, it can be obtained as a relatively high foaming product, and can be obtained without the need for a special chemical blowing agent.

In the above process, if the degree of heating 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 process is lost. For this purpose, foamed particles made of a biodegradable resin having a low melting point are separately added as foamed particles, or a component having an adhesive function such as a powder of a degradable resin having a low melting point, a thermoplastic resin, and a paste. May be added.
Other adhesive components referred to in the present application include starch paste, paste, gum arabic, glue, casein, linseed oil, starch derivatives such as starch acetate and carboxymethyl starch, fibrous derivatives such as methyl cellulose and ethyl cellulose, sodium alginate, locust bean Gum, vinyl-based synthetic paste such as polyvinyl alcohol, vinyl-based synthetic paste such as vinyl acetate-acrylic acid copolymer, acrylic-based synthetic paste such as sodium polyacrylate, styrene-based synthesis such as styrene-maleic acid copolymer In addition to adhesives such as natural, semi-synthetic, and synthetic pastes such as glue, a solution in which various resins are appropriately dissolved in a solvent, or a solvent that softens and swells a biodegradable resin may be used. When the foamed granules are aggregated together with these adhesive components and then heated and pressed, the foamed granules are fused and mechanically entangled in the same manner as in the above-described embodiment, and are fused or adhered by the adhesive components. As a result, the whole is shaped into a specific shape.

Further, as a post-processing step, if it is intended to endure a heavy load and have a long life, then it may be coated with a water-resistant paint or the like. In the present invention, in addition to the above, a sheet-like material is obtained between flat molds, a tray-like shape is formed, and various shapes are formed as a cushioning material for set goods, glass products, precision equipment, high-quality fruits, and the like. It can be used in the same manner as when a conventional foam such as styrene foam is used. In the above embodiments, pellets of Mater-Bi "Mataby" (registered trademark) are used as the biodegradable resin, and salad oil is 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 can be applied even when it comes into contact with a gaseous and filled atmosphere, The pre-treatment step and post-treatment step such as a water-containing step, centrifugation, washing, drying, and painting are not always necessary and can be added as appropriate. In addition, when the oil is a drying oil or fat, it may be used as an adhesive component. Therefore, the oil may be used as an adhesive component without collecting the oil adhering to the foamed granules. Further, in the above-described embodiment, the molding was performed once each time in a batch-type molding die. However, when a continuous rod-shaped aggregate having a predetermined cross section is required, it is gradually extruded into a cylindrical molding die. And / or may be heated and / or pressurized to continuously shape. Further, in the above embodiment, the heating and the pressurizing are performed. However, even when either one of them is applied, the foamed particles are mutually fused, bonded, or mechanically entangled. Alternatively, the outermost shell may be solidified and confined, or may have a specific integrated whole 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 the garbage pollution which is an important issue.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state of a water-containing step as a pretreatment step in one embodiment 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 an embodiment 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 embodiment of the method for molding a biodegradable resin of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biodegradable resin 2 Container 3 Water 4 Pot 5 Oil 6 Gas range 7 Mold 7a Upper die 7b Lower die 71 Guide pin 8 Heater (heating means) 10 Foamed particles of biodegradable resin

Claims (2)

(57) [Claims] 1. A step of bringing granules of a biodegradable resin containing water into contact with an oil heated to a boiling point of water or higher to vaporize water-containing water in the biodegradable resin, and obtaining the biodegradable resin obtained thereby. A process of assembling a large number of expanded granules of the above, and heating and / or pressurizing the whole to integrate them. 2. A step of bringing particles of a biodegradable resin containing water into contact with an oil heated to a boiling point of water or higher to vaporize water-containing water in the biodegradable resin, and obtaining the biodegradable resin obtained thereby. A process of assembling a large number of foamed granules together with an adhesive component, and heating and / or pressurizing the whole to integrate them.