JPH11314277A - Biodegradable resin composition and molding method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable resin composition, which can expand a biodegradable resin even to high expansion without requiring a special chemical expanding agent, the its processing technique. SOLUTION: A biodegradable resin composition is formed by aggregating a large number of biodegradable resins 1, each of which is expanded by being added with water 3 and the whole of which is shaped into a proper shape. Further, a processing method has a process for positively including the water 3 in the biodegradable resin, a process for boilingly evaporating water content in the biodegradable resin by heating the biodegradable resin up to the temperature higher than the boiling point of the water 3 and a process for aggregating a large number of biodegradable resin 1 expanded particles and integrating the whole particles under either heat or pressure or both the heat and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to Japanese Patent Application No. 4-119493 (Japanese Unexamined Patent Application Publication No. 10-158) related to the earlier application of the present applicant.
No. 427) A biodegradable resin composition, which is a part of the invention disclosed in "Method of molding biodegradable resin" and has recently been more and more spotlighted as "friendly to the earth" and "friendly to the environment". In particular, the present invention relates to a novel composition capable of achieving their foaming without requiring a special chemical foaming agent, and a method for molding the same.

[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 packing cushioning materials, heat insulating materials, and packaging trays, which require only a large volume, sorting and collecting are not worth the cost, and are not suitable for use on the sea or coastline. It was an annoying thing that stood out 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.

In order to meet such technical requirements, the present applicant has already filed Japanese Patent Application No. 4-119493 (Japanese Unexamined Patent Application Publication No.
No. 158427) The technology is disclosed as a "biodegradable resin molding method". Particularly, its usefulness as a "biodegradable resin composition" was evaluated. For the decomposable resin composition and its molding method ”.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a biodegradable resin composition which can cope with high foaming without requiring a special chemical foaming agent and can be foamed. It aims to provide molding technology.

[0006]

That is, the biodegradable resin composition according to claim 1 is formed by assembling a large number of foamed biodegradable resins containing water and shaping the whole into an appropriate shape. It is characterized by the following. In addition, the biodegradable resin composition according to claim 2, in addition to the above requirements, that water is positively added to the biodegradable resin, and that the water is contained at or above the equilibrium moisture value of the biodegradable resin. It is a feature. Furthermore, the biodegradable resin composition according to claim 3 is characterized in that, in addition to the above requirements, the biodegradable resin is a cellulose ester compound. Furthermore, the method of molding a biodegradable resin composition according to claim 4 is a step of positively containing water in the biodegradable resin, and heating the biodegradable resin to a temperature equal to or higher than the boiling point of water. A step of boiling and evaporating the biodegradable resin in the biodegradable resin, and after assembling a large number of foamed particles of the biodegradable resin obtained by this, the whole is integrated by one or both of heating and pressing And a process. Furthermore, in addition to the above requirements, the method for molding a biodegradable resin composition according to claim 5 further comprises a step of positively containing water in the biodegradable resin, and heating the biodegradable resin to a temperature higher than the boiling point of water. Then, the step of boiling and evaporating the contained water in the biodegradable resin, and after assembling a large number of foamed granules of the biodegradable resin obtained with the adhesive component, the whole is heated or pressurized And / or a step of integrating them by one or both. Furthermore, the molding method of the biodegradable resin composition according to claim 6 is:
In addition to the above requirements, the biodegradable resin is a cellulose ester compound. The present invention aims to achieve the above object.

In the present invention, when the water content of the biodegradable resin is exposed to a high temperature atmosphere, the biodegradable resin receives ambient heat and evaporates. On the other hand, since the biodegradable resin is softened or melted by the surrounding high temperature atmosphere, the biodegradable resin expands, that is, foams due to the vapor pressure of boiling and vaporizing inside. If necessary, a large number of the obtained foamed particles are assembled together with the adhesive component, and if the whole is subjected to one or both of heating and pressurizing, the mutual contact portions are fused or adhered. Then, they are mechanically entangled or the outermost shape is solidified and confined, so that a specific overall shape is formed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a biodegradable resin as a constituent element of the present invention will be described, then a biodegradable resin composition using the same will be described, and a method of molding the biodegradable resin composition will be described. Will be specifically described. The biodegradable resin in the present invention means a resin material whose physical properties are deteriorated based on a biological action. There is a type given. The former type includes products produced by microorganisms, products made from natural polymers, products produced from petroleum-based raw materials, and the like.The latter type contains blends with starch and blends with aliphatic polyesters. Etc. These biodegradation mechanisms have various forms, such as degradation by enzymes such as lipase, amylase, cellulase, and protease, degradation by microorganisms in activated sludge and the like, and degradation by soil in natural environments such as forests and cultivated lands. More specifically, polyhydroxybutyric acid and its derivatives, pullulan, a cellulose-chitosan mixture, an esterified product of cellulose, amylose and wood flour, a polyester-nylon copolymer, a polyester copolymer, and a 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 5, which is an example of a high-temperature atmosphere heated above the boiling point of water, may be various oils such as animal oils, vegetable oils, mineral oils, and synthetic oils, but has high safety and low viscosity. Those which can be easily separated and recovered later are suitable.

In this embodiment, pellets of Mater-Bi "Mataby" (registered trademark) sold by Nippon Synthetic Chemical Industry Co., Ltd. are used as the biodegradable resin.
A commercially available edible salad oil was used. 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. Also, its melting point is around 140 ° C,
The biodegradation is promoted by absorbing water and swelling, and shows biodegradability equivalent to that of paper in an environment where microorganisms can survive.

[0010] The biodegradable resin composition according to the present invention is provided by providing a water-containing step of positively including water in the biodegradable resin as described above for foaming. Specifically, as shown in FIG.
Pour the biodegradable resin 1 in the form of pellets
Was soaked for 10 hours. 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, the biodegradable resin containing the equilibrium moisture may be used as it is without leaving a step that is an apparent moisture-containing step without being provided. . Of course, in this case, it seems that there is no apparent water-containing step, but whether or not water can be absorbed depends on humidity conditions, temperature conditions, ventilation conditions, and the like in the atmosphere. When the conditions are satisfied and sufficient equilibrium water is obtained, measures are taken to leave the biodegradable resin for water addition, and this step is essentially a so-called active water-containing step. It becomes.

A process of placing the device in a high-temperature atmosphere following the water-containing process will be described. The biodegradable resin composition of the present invention comes into contact with a high-temperature oil 5 which is an example of an atmosphere heated to a temperature higher than the boiling point of water. In the embodiment of the present invention, a salad oil, which is an example of the oil 5 filled in the pot 4, is supplied to a gas range 6 under the normal atmospheric pressure of normal temperature and humidity, as shown in FIG.
To about 130 ° C. to 180 ° C., and the water-containing biodegradable resin 1 obtained through the water-containing step was dispersed and dropped in the salad oil in the form of pellets.

[0012] 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 at the initial stage of the oil immersion may be obtained as a cluster-like mass which is fused and foamed.

In this embodiment, the temperature of the oil 5 is set to 160
When the foaming ratio is about 8 to 10 times, the foaming rate can be expanded to about 8 to 10 times, which is far higher than the foaming rate of about 2 times obtained by adding a few percent of a commercially available chemical foaming agent. High foaming was achieved. The foamed biodegradable resin thus obtained is then centrifuged or washed,
It is desirable that the adhering oil is separated and collected by drying or the like, and the separated and collected oil may be used as oil for the next process. In addition, if the temperature of the oil 5 in this step is low, the biodegradable resin slowly reaches the softening point or melting point, and the steam pressure due to the boiling vaporization is not used at a stretch. Then, the vaporized water vapor is released at a stroke, so that a relatively highly foamed water vapor can be obtained.

In the present embodiment, the foamed biodegradable resin particles 10 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 in consideration of a predetermined filling rate is placed in the cavity of the mold 7. In the molding die 7, an upper die 7a and a lower die 7b are guided by guide pins 71, 71 and are vertically movable.
As shown by the chain double-dashed line A, the upper mold 7a and the lower mold 7b are confined to form a cavity having a thick section in the inside. The upper die 7a and the lower die 7b are provided with a heating means, in the illustrated embodiment, a heater 8, so that the foamed granules 10 placed in the cavity can be heated through the molding die 7. Also, the mold 7
The whole 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 molding die 7 is energized in advance, or the energized granule 10 is 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.
When the lower mold 7b is closed, the internal firing granules 1
0 is partially crushed and interlocks with each other, and some are welded to each other. In particular, in a portion which comes into contact with the inner wall of the molding die, the relatively close fused foam particles are fused together, and the outer shell Becomes one 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, pressing by the press machine is stopped, the upper mold 7a and the lower mold 7b are opened, and the cabinet is opened. If the molded product in the tee is taken out, the aggregate of the foam particles 10 can be obtained as a thick angle rod. In addition,
At this time, in order to ensure the internal fusion or the like, the heating can be interrupted during the pressurization, or the cooling can be actively performed.

The thus obtained thick angled rod, which is a collective molded product of the biodegradable resin foam particles 10, can be used as a corner support or the like for a package in a cardboard box for packaging. it can. This is because even if it is illegally dumped, it will biodegrade, so if it drifts on the sea or hits the coastline, it will be decomposed in a while,
Moreover, even if it is left on the ground, it decomposes by absorbing rain and rain and moisture in the ground, so 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 foam 10 by relatively high foaming in the previous process is lost. For this purpose, as a foamed particle, a foamed particle made of a biodegradable resin having a low melting point is separately added, or a powder of a degradable resin having a low melting point, a thermoplastic resin, or a component having an adhesive function such as a glue. 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 Including glue, natural, semi-synthetic, and synthetic glue, as well as adhesives, as well as solutions in which various resins are appropriately dissolved in solvents, and solutions in which biodegradable resins are appropriately dissolved in solvents, and softening of biodegradable resins It may be a solvent or the like that swells. If the foamed particles are aggregated together with these adhesive components and then heated and pressed, the foamed particles are fused or bonded together as in the above-described embodiment, and the whole is shaped into a specific shape. Will be.

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 embodiment, the Biodegradable resin 1 is provided with Mater-Bi “Mataby” (registered trademark).
Was used, and salad oil was used as the oil 5. However, the present invention is not limited to these. Other biodegradable resins are used for the biodegradable resin, and their shapes are not pellets. In both cases, those having a sheet shape, a fibrous shape, or an appropriately shaped shape can be used, and other oils can be used as the oil for creating a high-temperature atmosphere. Further, depending on the case, even if the heated oil does not come into contact with the biodegradable resin as a liquid but comes into contact with the gas in a gas-filled atmosphere, it can be applied. In addition, it is essential to add water to the biodegradable resin in the water-containing step, but centrifugation in the foaming step,
Various steps such as washing and drying are not always necessary, and can be added as appropriate. Also, when the oil is a drying oil, it may be used as an adhesive component,
The oil adhering to the foam particles may be used as it is as an adhesive component without collecting the oil. Further, in the above-described embodiment, the molding is performed once each time by a batch-type forming die. However, when a continuous rod-shaped collective molded product having a predetermined cross section is required, a so-called extruded cylindrical forming die is gradually used. The shape may be continuously formed by one or both of heating and pressing. In the above embodiment,
Heating and pressurizing are applied, but even when either one of them is applied, the foam particles are fused together, bonded, mechanically entangled, or the outermost It may be closed and closed to present an integrated specific overall shape.

[0019]

According to the present invention, the biodegradable resin can cope with high foaming without requiring a special foaming agent, and can be provided as a substitute for a conventional foam. It can contribute to the reduction of garbage pollution.

[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 a method for molding a biodegradable resin composition of the present invention.

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

FIG. 3 is a perspective view including a partial cross section of a molding die showing a state of a shaping step in another embodiment of the method for molding a biodegradable resin composition 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 10 Foamed particles of biodegradable resin

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 04

Claims (6)

[Claims] 1. A biodegradable resin composition obtained by assembling a large number of biodegradable resins foamed with water and forming the whole into an appropriate shape. 2. The biodegradable resin buffer material according to claim 1, wherein water is positively added to the biodegradable resin and is contained in an amount equal to or higher than the equilibrium moisture value of the biodegradable resin. 3. The biodegradable resin composition according to claim 1, wherein the biodegradable resin is an ester compound of cellulose. 4. A step of positively containing water in the biodegradable resin, and heating the biodegradable resin to a boiling point of water or higher.
A step of boiling and evaporating the contained water in the biodegradable resin, and after assembling a large number of expanded granules of the biodegradable resin obtained by this, the whole is integrated by one or both of heating and pressing. And a step of molding the biodegradable resin composition. 5. A step of positively containing water in the biodegradable resin, and heating the biodegradable resin to a temperature equal to or higher than the boiling point of water.
A step of boiling and evaporating the contained water in the biodegradable resin, and after assembling a large number of foamed granules of the biodegradable resin obtained with the adhesive component, heat or pressurize the whole. A method for forming a biodegradable resin composition, comprising the steps of: 6. The method for molding a biodegradable resin composition according to claim 4, wherein the biodegradable resin is an ester compound of cellulose.