JP2000141396A - Production of molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substitute returning to soil simply and friendly to environment by compounding a biodegradable resin and food leavings in a definite ratio to subject them to injection molding. SOLUTION: Food leavings selected from bean-curd refuse, food leavings generated from a corn milling process and coffee grounds are dried to be adjusted to 5-10% in moisture content. Further, a pretreatment process for finely dividing food leavings to reduce the size thereof to 30 μm or less and an injection molding process charging a biodegradable resin and the pre-treated food leavings in a compounding ratio of (49-65):(51-35) and subjecting them to injection molding to produce a molded product are included.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molded article using an injection molding technique, and more particularly to an injection molding technique using a biodegradable resin and food residues as raw materials. The present invention relates to a method for manufacturing a molded product.

[0002]

2. Description of the Related Art Plastic products manufactured by using an injection molding technique are highly evaluated in terms of moldability, strength and the like, and are now widely used. However, since plastic products are derived from petroleum, when they are disposed of by burning, harmful gases are generated, and in some cases, highly toxic substances such as dioxin are generated. On the other hand, promoting landfill is unrealistic at present when it is difficult to secure landfill sites. Therefore, from the viewpoint of environmental protection, development of a product replacing plastic products is required.

[0003] Biodegradable resins have attracted attention recently because they are degraded by microorganisms and return to soil or dissolve in water, so that they are environmentally friendly. However, as a substitute for plastic products, when injection molding technology is used, the moldability is poor due to low fluidity, and the price is expensive. Has not been reached.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a molded product which can solve the above-mentioned problems, has good moldability and is satisfactory in price, and can replace conventional plastic products. I do. Another object of the present invention is to provide a method for manufacturing a molded product using a biodegradable resin as one raw material and utilizing injection molding technology. Further, another object of the present invention is to provide a method for producing a molded product using a biodegradable resin and a conventionally discarded food residue or the like as raw materials.

[0005]

Means for Solving the Problems As a result of earnest research, the present inventors have surprisingly found that a certain ratio of a biodegradable resin and a specific food residue is blended and injection-molded.
They have found that a molded product that can sufficiently compete with conventional plastic products in terms of moldability, price, and the like can be manufactured, and have come to propose the following invention. The invention according to claim 1 is a method for producing a molded product, comprising drying food residues selected from food residue or coffee residue generated in a process of milling okara and corn to a water content of 5 to 10%; A pretreatment step of finely pulverizing food residues having a size of 30 μm or less, and a biodegradable resin and the food residues, 49 to 6;
5: 51-35, and injection molding to produce a molded product by injection molding.

[0006]

Embodiments of the present invention will be described below. (Raw materials) Biodegradable resin Any resin may be used as long as it can be decomposed by microorganisms such as bacteria. For example, there is a lactic acid-based biodegradable resin represented by the following general formula.

[0007]

Embedded image The above biodegradable resin is available from Shimadzu Corporation
Product name "Rakuti" ($ 5000 series, $ 9000)
Series). In addition, there is an aliphatic polyester resin represented by the following general formula.

[0008]

Embedded image The above biodegradable resin is available from Showa High Polymer Co., Ltd.
Product name "Bionore" (chemical name "polybutylene succinate (PBS) (# 1000 series), chemical name" polybutylene succinate adipate (PBSA) (# 3
000 series)). In this,
A preferred biodegradable resin is Lacty. Lacty has the following structure, is completely decomposed into water and carbon dioxide by the action of microorganisms in soil and water, and requires less energy for combustion.

[0009] 2. Food residue The food residue used is food residue or coffee residue generated in the okara, corn milling process. Okara is squeezed residue of soy milk produced in the process of producing tofu. The main component is fiber, but it also contains some protein and fat. The main component of food residue from the corn milling process is corn starch (corn starch), but it also contains some protein and fat. The coffee residue is a residue generated after grinding and roasting the coffee beans corresponding to the high, excluding the skin and the fleshy part in advance. For example, a large amount of coffee residue is produced when producing a coffee beverage for canned coffee. Most of the above-mentioned food residue is currently disposed of as industrial waste.

(Manufacturing method) Pretreatment step The food residue is dried to a water content of 5 to 10%. By using food residues having a water content of 5 to 10% by weight, sufficient fluidity can be imparted to the biodegradable resin, and thus the water content is limited to the above range. Drying is performed by heating in the air. Then, it is pulverized and sieved to a size of 30 microns or less.
If the size of the food residue exceeds 30 microns, the surface properties of the molded article may be adversely affected, so the size is limited to the above range. Preferably, the size is 2
Those having 0 to 30 microns are 80% or more.
The food residue and the biodegradable resin that have been pretreated as described above are charged into a commercially available mixer and mixed well. In addition, a biodegradable resin and food residue are 49-65: 51-
The mixture is charged into a mixer at a weight ratio of 35 and mixed.

2. Injection molding process A commercially available injection molding machine is used. For example, an injection molding machine provided with a mixer schematically shown in FIG. 1 is used. The injection molding machine 1 is a commonly used in-line screw type machine for plastic injection molding, and includes a mixer 3, a hopper 5, a heating cylinder 7, a mold 9, and a temperature controller 11. Etc. On the heating cylinder 7, four heaters 13 (H-3, H-2, H-1, H-
N). H-3 is located farthest from the gate of the cavity of the mold 9 (not shown) of the mold 9, and is positioned so as to approach the gate (not shown) in the order of H-2, H-1, and HN. I do. The temperature controller 11 is provided for cooling and heating the mold. In addition, a screw back pressure adjusting valve (not shown) is provided to adjust the screw back pressure.

The injection molding process will be described below. When the biodegradable resin X and the food residue Y are charged into the mixer 3, they are sufficiently mixed there to form a homogeneous mixture. Mixture Z is
After passing through the hopper 5, it is further fed into the heating cylinder 7 heated by the heater 13. Inside the heating cylinder 7, the rotation of the screw (not shown) plasticizes the mixture and accumulates at the tip of the screw as a homogeneous melt. After the screw has receded a certain distance due to the accumulated pressure of the melt, it will now turn forward and
Acting as a plunger, the melt is injected from a nozzle (not shown) towards the gate. The injected melt is held in the cavity of the mold 6 for a certain period of time, solidified to form a molded product, and then taken out of the mold 6.

(Use of molded article) The molded article of the present invention has moldability and strength equal to or higher than that of a plastic product molded by conventional injection molding, and is therefore used in the same manner as a conventional plastic product. It can be used in That is,
The molded article of the present invention contains okara containing a large amount of fibers, so that the strength of the molded article is improved, and the molded article has higher strength than conventional articles.

(Disposal of Molded Article) The molded article produced by the production method of the present invention can be promptly returned to soil by the cooperative action of the biodegradable resin and food residue. In particular, when okara is used as a food residue, the okara activates the activity of microorganisms such as bacteria and can be returned to the soil more quickly. Further, the molded article produced by the production method of the present invention does not generate harmful substances as in conventional plastic products even when burned. Therefore, when discarded, the molded article of the present invention may be returned to soil as it is or may be subjected to combustion treatment.

[0015]

EXAMPLES A molded product was manufactured according to the following manufacturing method. The raw materials used are as follows.

[0016]

[Table 1]

Each of the biodegradable resins described in Table 1 is specifically a lactic acid-based biodegradable plastic, and is a # 9000 series manufactured by Shimadzu Corporation under the trade name "Lacty". The specific physical data are as follows.

[0018]

[Table 2]

Using the same type of injection molding machine as described in the above embodiment (capacity: 170 tons, manufactured by Toshiba Machine Co., Ltd.), injection molding was performed under the following conditions. The amount of raw materials (biodegradable resin and food residue) charged into the hopper 5 was 100 kg per charge.

[0020]

[Table 3]

As shown in Table 2, the product of the present invention, Comparative Product 1 and Comparative Product 2 described in Table 1 were injection-molded according to processing conditions 1, and Comparative Product 3 and Comparative Product 4 Injection molding was performed according to condition 2. The holding pressure was changed on the way. The times of the first and second stages were almost the same. The injection amount was changed by changing the forward speed of the screw twice in the middle. The times of the first stage, the second stage and the third stage were almost the same. When cooling the mold 9, the mold 9 was cooled.

The shape of the obtained molded product 20 is shown in FIG. This is a simple coin purse. The wall thickness was set to about 2-3 mm. The dimensions were set to about 18 cm in the vertical direction (l), about 8 cm in the horizontal direction (t), and about 3 cm in the height (h). Reference numeral 23 indicates a degassing portion.
Reference numeral 25 indicates a gate.

The product of the present invention (biodegradable resin 60%) was excellent in moldability. Comparative product 1 (60% biodegradable resin)
Defects such as blistering, clouding, and wetting caused by gas accumulation occurred. Comparative product 2 (60% biodegradable resin) had poor surface properties. Comparative product 3 (100% biodegradable resin)
However, despite the fact that the heat melting temperature of the raw material was higher than that of the product of the present invention, the fluidity was low, so that the material was cut off. In addition, blister caused by gas accumulation,
Defects such as cloudiness and we occurred. Further, the releasability was poor. Comparative Product 4 (80% biodegradable resin) was less than Comparative Product 3, but suffered the same defects as Comparative Product 3.

[0024]

As described above, according to the method for producing a molded product of the present invention, an injection molded product having the same form as a conventional plastic product can be produced. In the method for producing a molded product of the present invention, molding can be performed using a general injection molding machine. Further, the molded article produced by the production method of the present invention can be disposed of by returning it to soil as it is. Also, when burned, unlike conventional plastic products, no harmful substances are generated.

[Brief description of the drawings]

FIG. 1 is a schematic view of an injection molding machine that can be used when carrying out the production method of the present invention.

FIG. 2 shows a molded article (coin purse) manufactured in an embodiment of the present invention.
It is a perspective view of.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection molding machine 3 Mixer 5 Hopper 7 Heating cylinder 9 Die 13 Heater 20 Molded product 23 Gas release part 25 Gate

Claims (1)

[Claims] 1. A method for producing a molded article, comprising drying food residues generated from a process of milling okara or corn, or food residues selected from coffee grounds to reduce the water content to 5%.
And a pretreatment step of food residues to be pulverized to a size of 30 μm or less, and a biodegradable resin and the food residues are 49-65: 51-51.
An injection molding step of producing a molded product by injection molding at a mixing ratio of 35 and injection molding.