JP2001129867A - Manufacturing method for foam utilizing waste produced in pet bottle recycling process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that un-utilized scrap material amounting to about 30% of the scrap materials in a PET bottle recycling process is produced, the unused scrap material cannot be recycled as material due to the mixed inclusion of PE, PP or the like in addition to PET and their coloring, and incineration of the material could damage an incinerator due to its high colorific value at their disposal. SOLUTION: Polypropylene of 200 pts.wt., 700 pts.wt. of corn starch, and 20 pts.wt. of calcium carbonate are added to 100 pts.wt. PET bottle scrap material so as to kneaded for 20 min and then charged in the hopper of a twin-screw extruder in order to be kneaded, heated, melted and pressurized under the feeding of water so as to be discharged through a tip opening part in the air and expanded, resulting in obtaining a foam having the expansion ratio of about 5,000%. The foam can be used as a buffering material and a heat insulating material. In addition, the heat value at its incineration is about one half of that at the incineration of foamed polystyrene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a means for effectively utilizing waste materials generated in a PET bottle recycling process.
The foam is continuously discharged by an extruder and used as a cushioning material and heat insulating material to promote the recycling of PET bottles, and to prevent damage to the incinerator when disposing of the product. The present invention relates to a method for producing a foamed material in which the calorific value at the time of combustion is suppressed to the level of wood in consideration of the component ratio.

[0002]

2. Description of the Related Art In order to promote the recycling of PET bottles, PET bottles separated and recovered from the market, after removing bottles made of materials other than PET, crushing and washing,
Pure PET flakes with a length of 8 mm or more are extracted and reprocessed mainly into fibers, etc. However, even colored pure PET flakes and fine powders with a length of 8 mm or less are not sufficiently reused and are ground at the same time. PET bottle caps and labels are disposed of as waste, 30% of the weight of the collected PET bottles is disposed of, new industrial waste is generated, and recycled materials are recycled. The low utilization rate has hindered the spread of PET bottle recycling.

[0003]

In the PET bottle recycling process, bottles and the like made of different materials are separated and eliminated, then crushed into flakes, washed and sorted, and pure PET flakes, cap crushed flakes, labels and other crushed. Flakes can be roughly classified into three types, but pure PET flakes are not allowed to be reused as raw materials for original PET bottles. Therefore, the development of products using recycled materials is urgent. In particular, cap crushed flakes, labels and other crushed flakes are hardly reused and are disposed of as industrial waste.

[0004] The above-mentioned cap crushed flakes, labels and other crushed flakes are made of raw materials other than PET, such as PE,
Not only PP and other materials are mixed, but also the size of flakes is from fine powder to 10 mm or more, and there is a problem that they are colored or printed. Reuse was difficult.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention focuses on products and processing fields which can be used even if their properties as plastic products are inferior.
A foam obtained by continuous foaming using an extruder using water as a foaming agent has been developed. Further, by setting the plastic component ratio in the foam to 30% or less, the calorific value during incineration can be suppressed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention reuses flakes generated in a plastic bottle recycling process, which had been discarded because they could not be effectively used in the past, without damaging the incinerator when disposing after use. As described above, a method for producing a foamed material in which the plastic component ratio is suppressed to 30% or less is provided.

In the present invention, the ratio of the plastic component is set to 30% or less in order to suppress the amount of heat generated during incineration.
At that time, as a component other than the plastic component, corn starch, a vegetable organic component represented by paper and a porous inorganic component represented by calcium carbonate are used, but the plant organic component is not limited to corn starch and paper, Any fine particles such as wood flour can be used. Also, the porous inorganic component is not limited to calcium carbonate, but is obtained in a porous and fine particle state, or in a manufacturing process,
For example, any material that can be atomized in an extruder can be used. However, in any case, it is a prerequisite for mass production that homogeneous, continuously available, and inexpensive.

According to the present invention, a foamable composition is composed of flakes generated in a PET bottle recycling process and calcium carbonate added, corn starch and paper are added as fillers, and the mixture is agitated and mixed, and then extruded. A continuous foam is obtained by throwing into a hopper of the machine, kneading, heating, melting and pressurizing while supplying water, and discharging and expanding into the atmosphere.

When only the flakes generated in the PET bottle recycling process are used as the plastic component constituting the foamable composition described above, the foaming ratio at the time of discharge and expansion is about 15 times, and the bulk specific gravity is reduced. growing. When it is desired to increase the expansion ratio, the expansion ratio can be increased to about 50 times by adding a compatible plastic material. In addition, by selecting an appropriate plastic material and filler, a foam having arbitrary characteristics such as elasticity and hardness can be obtained.

As the foamable composition, a plastic material,
After kneading the plant organic component and the porous inorganic component, water is added as a blowing agent, and in order to obtain a uniform foam, it is important that the components are uniformly dispersed. For this purpose, if the flakes generated in the PET bottle recycling process are as large as 8 mm or more, the flakes are reground and then the required amount of plastic, vegetable organic components and porous inorganic components are added, and the mixture is stirred and kneaded with a mixer. It is desirable to supply the composition to an extruder. Also, the extruder is kneading
It is indispensable to use a biaxial system in which the structural parts responsible for the heating and pressurizing functions are rearranged, and the kneading / shearing heat effect and the discharge pressure suitable for the properties of the composition can be obtained.

[0011]

Embodiments of the present invention will be described below. Example 1
Is pure PET less than 8 mm long, which is excluded as unusable from those collected as pure PET flakes.
To 30 kg of flakes, 70 kg of corn starch and 2 kg of calcium carbonate were added, and the foamable composition stirred and mixed at room temperature with a mixer was supplied to a hopper of a twin-screw extruder having a screw diameter of 47 mm, and the mixture was continuously added to the mixture. While supplying water, kneading, heating and melting
At an extrusion speed of kg / hour, the mixture is discharged into the atmosphere from a discharge opening having an inner diameter of 3 mm maintained at 170 to 190 degrees Celsius,
A continuous discharge product having a diameter of 13 mm was obtained. At this time, the molding conditions of the extruder were such that the supply of water was 5-6 liters / hour, the temperature of the mixture immediately before the heated and melted discharge opening was 170-185 degrees Celsius, and the internal pressure was 30-45 kg / hour.
It was set to be maintained at cm2.

A second embodiment will be described below. 8m above
15 kg of pure PET flakes of m length or less, 15 kg of polypropylene in pellet form, 70 kg of corn starch,
And 2 kg of calcium carbonate were added, and the foamable composition was stirred and mixed at room temperature with a mixer.
Example 1 was fed to a hopper of a 7 mm twin screw extruder.
Under the same conditions as described above, the mixture was discharged into the atmosphere to obtain a swollen continuous discharge having a diameter of 18 mm.

A third embodiment will be described below. In the PET bottle recycling process, 20 kg of pelletized polypropylene, 70 kg of corn starch, and 2 kg of calcium carbonate were added to 10 kg of the material obtained by recrushing the crushed and crushed cap flakes in the PET bottle recycling process, and the mixture was stirred and mixed at room temperature with a mixer to form a foam. Screw with a screw diameter of 47
mm to a hopper of a twin-screw extruder, and discharged into the atmosphere under the same conditions as in Example 1 to obtain a continuous discharge product expanded to a diameter of 25 mm.

A fourth embodiment will be described below. In the PET bottle recycling process, 10 kg of the material obtained by re-grinding the crushed and sorted labels and other crushed flakes, 20 kg of pelletized polypropylene, 70 kg of corn starch,
And 2 kg of calcium carbonate were added, and the foamable composition was stirred and mixed with a mixer at room temperature.
Example 1 was fed to a hopper of a 7 mm twin screw extruder.
Under the same conditions as described above, the mixture was discharged into the atmosphere to obtain a continuous discharge expanded to a diameter of 20 mm.

The results of measuring the properties of the foams obtained in Examples 1, 2, 3, and 4 will be described. The weight and volume of the obtained foam were measured, and the bulk specific gravity was calculated. As a result, Example 1 was 0.06, Example 2 was 0.05, Example 3 was 0.02, Example 4 was 0.03.
When this is expressed by a foaming ratio, Example 1 is approximately 17 times,
Example 2 is about 20 times, Example 3 is about 50 times, and Example 4 is about 30 times. In addition, since the hardness is correlated with the expansion ratio, it has been found that the hardness can be adjusted in accordance with the use standard of the cushioning material.

In the foam of the above embodiment, the plastic component ratio is set to 30%, but the amount of heat generated during combustion of a sample made of the same components as the foam is JIS.
According to the measurement method based on M8814, about 5,900 ca
1 / g, which means that the styrofoam product has a calorific value of about 10,000 cal / g and the wood has a calorific value of about 5,400.
It was found that the cal / g was almost the same as wood.

[0017]

The present invention is embodied in the form described above and has the following effects.

The production method of the present invention makes it possible to reuse waste material flakes generated in the PET bottle recycling process, which had been discarded without being used conventionally, as a raw material. The use of recycled materials is expected to increase, and the incinerator will not be easily damaged when disposed after reuse because the calorific value during combustion is low.

Since the foam produced by the production method of the present invention can be expected to be used as a substitute for a cushioning material using styrene foam as a raw material, the consumption of styrene foam, which causes environmental destruction, is reduced. Has an effect.

The foam produced by the production method of the present invention uses waste generated in the PET bottle recycling process, uses plant organic components and inorganic components as fillers, and reduces the ratio of expensive plastic materials. Since it is as low as 30% or less, material costs can be reduced and disposal costs can be reduced.

Claims (4)

[Claims] 1. A waste material generated in a PET bottle recycling process is used as a raw material of a foamable composition using water as a foaming agent, and is kneaded, heated, melted and pressurized by an extruder, and discharged into the atmosphere. A method for producing a foamed material which expands to obtain a foam, wherein a ratio of a plastic component is suppressed to 30% or less,
A method for producing a foam having a calorific value during combustion comparable to that of wood. 2. A composition in which flake-like waste material generated in a PET bottle recycling process is crushed again by a fine crusher, and a plant organic component typified by corn starch and paper and a porous inorganic component typified by calcium carbonate are added. The product is kneaded with a mixer, then put into a hopper of an extruder, and kneaded, heated, melted and pressurized while supplying water, and discharged into the atmosphere from the opening at the tip and expanded to produce a foam. The method also includes a production method in which a pulverized waste material or a composition kneaded with a mixer is pelletized, pelletized, and supplied to an extruder to improve discharge efficiency. 3. The ratio of the plastic component is 30%.
In setting below, crushing of general-purpose plastic materials such as granular polyethylene (PE) and polypropylene (PP) or industrial waste containing these plastic components according to the plastic composition of waste materials generated in the PET bottle recycling process A production method in which the properties of the obtained foam, such as expansion ratio, elasticity, and hardness, can be arbitrarily adjusted by adding a product. 4. In the PET bottle recycling step, a bottle of dissimilar material made of a material other than PET (PET) is separated / excluded, then crushed into flakes, washed / sorted, and pure PET flakes. Cap crushed flakes,
Labels and other crushed flakes are roughly classified into three types. At present, only PET flakes are hardly reused and 30% of the input PET bottles are discarded. A production method in which foams can be obtained from all three types by a production method according to the composition of each flake.