JP2003011201A - Foamed molded object and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed molded object as a cushioning material or the like, and a method for manufacturing the same. SOLUTION: Starch and a thermoplastic resin are used as a principal raw material and a thermoplastic elastomer is added to the principal raw material and an additive being a foaming aid is added thereto to prepare a mixed raw material which is, in turn, equally mixed using a mixer 1 in a mixing process S1 to ensure a raw material mixture. Next, this raw material mixture is kneaded with water further supplied as a raw material under a predetermined high temperature/high pressure condition using an extruder in an extrusion process S2 to be heated and melted, and the kneaded molten mixture is extruded under normal pressure from the extrusion opening part of the extruder to mold a foamed molded continuous body which is, in turn, cut into a desired dimension using a cutter 3 in a cutting process S3 to manufacture the foamed molded object being a product used as the cushioning material or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed molded article that can be used as a cushioning material such as a foamed sheet, a block or a tube of a packing material and a method for producing the same.

[0002]

2. Description of the Related Art Foamed moldings of the prior art include foamed polystyrene resin, foamed polyethylene resin, polyvinyl chloride resin, etc. The method of manufacturing them is to decompose them by heating and pressurizing to generate nitrogen gas and carbon dioxide gas. A chemical foaming agent, a fluorocarbon-based foaming agent, a low boiling point hydrocarbon, or the like was used.

There are various types of foamed molded articles of the prior art, but, for example, in Japanese Patent Laid-Open No. 9-111029 "Method for producing loose cushioning material", a plant-based foaming agent, a polypropylene resin, a starch-based additive and water are used as raw materials. There is disclosed a method of manufacturing the loose cushioning material.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In conventional foamed polystyrene resins, foamed polyethylene resins, polyvinyl chloride resins, and other foamed molded articles, and methods for producing these,
Hazardous gas and black smoke are generated at the time of disposal after opening the packaging, which causes environmental pollution. Also, there is a problem that the incineration equipment becomes expensive due to the high calories burned during incineration.
Moreover, in these manufacturing methods, a chemical foaming agent that decomposes by heating and pressurizing to generate nitrogen gas and carbon dioxide, a fluorocarbon-based agent,
Since a foaming agent such as low boiling point hydrocarbon is used, and the foaming agent is expensive and has high volatility, it is difficult to handle.

In the prior art Japanese Unexamined Patent Publication No. 9-111029 "Method for producing loose cushioning material", since the raw material used is a hydrophilic raw material, a plant-based foaming agent, a starch-based additive and a polypropylene resin-based foaming agent are used. However, since it is difficult to obtain a sufficient elastic modulus and the water resistance is low, there is a problem in practical use that there is only the use of a bulk cushioning material for packaging that does not require strength. .

[0006]

In order to solve the above-mentioned problems, in the method for producing a foamed molded article according to claim 1 of the present invention, it reacts with water to cause a change in pressure and temperature. It is characterized in that starch, which has foaming characteristics, is actively used as a main raw material.

The foamed molded article according to claim 2 of the present invention is characterized in that a thermoplastic elastomer is added to enhance its elastic restoring property.

The foamed molded article according to claim 2 of the present invention contains a thermoplastic resin and a thermoplastic elastomer, and has a function of not generating a harmful gas during waste incineration and not damaging the furnace. And

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing a foamed molded article, which corresponds to claim 1 of the present invention, is a thermoplastic resin comprising starch, which has a foaming property under the conditions of pressure and temperature change by reacting with water, and polypropylene. A mixing step (S1) of a granular / powdered mixed raw material in which a resin is used as a main raw material, a thermoplastic elastomer is added to the main raw material, and other additives such as talc as a foaming aid are added. , The raw material mixture is uniformly mixed using a mixer, and then, in the extrusion step (S2), the extruder is used to
The raw material mixture is charged into the hopper of the extruder, and is kneaded, heated, and melted under a predetermined high temperature and high pressure condition while further supplying the raw material water from near the front of the cylinder.
It is discharged under normal pressure from the discharge opening of the extruder to form a foam molding continuous body, and then, in a cutting step (S3), the foam molding continuous body is cut into a desired size using a cutting machine. The feature is to provide a foamed molded product as a product used as a cushioning material or the like.

According to claim 2 of the present invention, the foamed molded article contains a thermoplastic resin composed of starch, polypropylene and the like as a main constituent component, a thermoplastic elastomer component, and further comprises talc and the like. It is characterized in that it has a foamed shape and has desired dimensions by including an additive component as a foaming aid.

The foamed molded article according to claim 2 of the present invention can be manufactured by using the method for manufacturing a foamed molded article according to claim 1.

In the foamed molded product of the present invention and the method for producing the same, as starch, corn starch, tapioca starch, wheat starch, potato starch, etc., and raw starch consisting of unpurified starch containing protein in addition to the starch component, α- Modified starches such as starches, oxidized starches, esterified starches and etherified starches, and celluloses and derivatives thereof such as carboxymethyl cellulose salts and methyl celluloses can be used.

In the foamed molded product and the method for producing the same of the present invention, as the thermoplastic resin, polypropylene, low density polyethylene, high density polyethylene, ethylene-propylene copolymer, ethylene vinyl acetate copolymer resin, polyolefin resin, poly Examples thereof include vinyl acetate, polyvinyl butyral, cellulose acetate, fatty acid polyester fat, and the like, and copolymers of these, vinyl acetate-
It is also possible to use a thermoplastic resin composed of a polyethylene copolymer, a polyethylene-acrylic acid copolymer, or the like. These have an advantage that no harmful gas is generated during waste incineration and the furnace is not damaged.

In the foamed molded product of the present invention and the method for producing the same, as the thermoplastic elastomer, a thermoplastic elastomer composed of an olefin elastomer, a urethane elastomer, an ester elastomer, an amide elastomer, a silicone elastomer or the like can be used. ， These have the advantage that no harmful gas is generated during waste incineration and the furnace is not damaged.

In the foamed molded product of the present invention and the method for producing the same, a foaming aid composed of talc, calcium carbonate, silica, mica, kaolin, activated carbon and the like can be used as an additive.

In the foamed molded product of the present invention and the method for producing the same, as an additive, for example, a fragrance, a colorant, a surfactant, a flame retardant, an antibacterial agent, a plasticizer may be used depending on the desired characteristics and application of the foamed molded product. A useful additive such as an agent may be added.

In the method for producing a foamed molded article according to claim 1 of the present invention, the foaming property of starch is that heating and pressurization is caused by the incorporation of water molecules due to the knitting structure due to the strong hydrogen bond of starch molecules. Under the conditions, the starch particles largely swell to form a viscous gelatinous substance, which is expanded by being discharged under normal pressure from the discharge opening of the extruder, so that a foaming action can be secured.

In the method for producing a foamed molded product according to claim 1 of the present invention, the method of supplying water as a raw material is not limited to the method of supplying in the extrusion step (S2), but the mixing step (S
In 1), it can be supplied directly.

In the method for producing a foamed molded article according to claim 1 of the present invention, the feed amount of water as a raw material is preferably 5 to 25 wt% as a raw material blending weight%, and when it is 5 wt% or less. Is difficult to foam, 25% by weight
In the above cases, the foamed molded product as a product has a function of shrinking to have a non-uniform cell structure or a low bulk density.

In the method for producing a foamed molded article according to claim 1 of the present invention, at a high temperature in the extrusion step (S2)
High-pressure conditions are temperature; 120-195 ° C, and pressure; 5
-100 kgf / cm ² is desirable.

In the foamed molded product of the present invention and the method for producing the same, the component weight% contained in the thermoplastic elastomer product is preferably from several% to 30% by weight, and the larger the component weight% is, the more the elastic restoring property is obtained. It has a good effect and increases the physical and mechanical strength such as compressive strength and the water resistance such as hygroscopicity and hygroscopic shrinkage resistance. When it is 2% by weight or less, sufficient elastic recovery is obtained. Has no effect.

In the foamed molded article and the method for producing the same of the present invention, the foamed molded article as a product is compared with a foamed resin made of expanded polystyrene (PS) or the like according to the prior art,
Physical and mechanical strength such as elasticity and compressive strength, and
With regard to water resistance such as hygroscopicity / moisture absorption and shrinkage resistance, it is possible to secure almost the same physical property values, and it has the effect of being able to be used as a cushioning material for foam sheets, blocks, tubes, etc. of packaging fillers.

In the foamed molded product and the method for producing the same of the present invention, since the foamed molded product as a product contains a thermoplastic resin and a thermoplastic elastomer as the resin-based raw materials, no harmful gas is generated during waste incineration, It has the function of not damaging the furnace.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings of the embodiment of the present invention, FIG.
FIG. 2 is a schematic view of steps of a method for producing a foamed molded article showing an example of the present invention, and FIG.
% Of raw material blended. FIG. 3 shows an embodiment of the present invention, wherein the weight percentage of the product constituents in the foamed molded article produced in Examples 1, 2 and 3 for the above-mentioned various formulations, and FIG. It is a product characteristic comparison with respect to the foaming molded article of this invention manufactured by 2 and 3, and the expanded polystyrene (PS) resin which is an example of the foaming molded article by a prior art.

An embodiment of the present invention will be described below. As shown in FIG. 1, the method for producing a foamed molded product is as follows. The starch reacts with water and has a foaming property under pressure and temperature change conditions, and polypropylene and the like. A mixing step of mixing granular raw materials, in which a thermoplastic resin is used as a main raw material, a thermoplastic elastomer is added to the main raw material, and other additives such as talc and the like as a foaming aid are added. In (S1), an evenly mixed raw material mixture is secured using the mixer (1), and then in the extrusion step (S2), the extruder (2) is used to feed the raw material mixture into the hopper of the extruder. Under a predetermined high temperature and high pressure condition, while further supplying water as a raw material from near the front part of the cylinder, kneading, heating and melting, and discharging under normal pressure from the discharge opening of the extruder. A foam molding continuous body is molded, and then, in the cutting step (S3), the cutting machine (3) is used to cut the foam molding continuous body to a desired size, and foam molding as a product used as a cushioning material or the like. It is characterized by providing a body.

The foamed molded articles according to the examples of the present invention include a thermoplastic resin composed of starch, polypropylene and the like as a main constituent component, a thermoplastic elastomer component, and talc and the like as another foaming aid. It is characterized in that it is a foamed body containing the additive component of 1. and having a desired size.

In the method for producing a foamed molded article of the embodiment of the present invention, as a raw material, as shown in FIG. 2, corn starch purified from corn or tapioca starch purified from cassava is used as a starch, and a thermoplastic resin is used. , Polypropylene (PP), olefin elastomer or silicone elastomer as thermoplastic elastomer, talc as additive, talc, and water are used. The blending weight% shown in FIG. 2 was applied corresponding to 1, 2, and 3.

In the method for producing a foamed molded article of the embodiment of the present invention, a twin-screw type extruder having an inner diameter of the discharge opening of 3 mm is used as the extruder (2), and any one of the embodiments 1, 2 and 3 is used. High temperature and high pressure conditions: temperature; 170-180 ° C, pressure;
40-55 kg weight / cm ² , extrusion rate: 100 kg /
Manufactured in time.

In the foamed molded article of the embodiment of the present invention, the product composition weight% of the foamed molded article is calculated from the compounded weight% of Examples 1, 2 and 3 of the method for producing the foamed molded article shown in FIG.
The water is in a vaporized state, and the component weight% is as shown in FIG.

In the foam molded article of the embodiment of the present invention, the product characteristics of the foam molded article are compared as shown in FIG. Then, according to the conventional technology, the bulk density, the compressive strength, the moisture absorption rate of expanded polystyrene (PS) using gas as a foaming agent,
The moisture absorption shrinkage resistance and elastic resilience are shown for comparison. In all cases, the foamed molded articles of the examples of the present invention have substantially the same physical property values as the foamed polystyrene (PS) of the prior art. This means that it can be used as a cushioning material for packing materials.

In the foam molded article of the embodiment of the present invention, the compressive strength in comparison of the product characteristics of the foam molded article was measured by cutting a product sample into a cylindrical body having a length of 20 mm and a diameter of about 15 mm, which was manufactured by Shimadzu Corporation Autograph. Then, attach a basket-shaped jig and compress the entire surface by 50% on the horizontal plate (length: 10 mm).
The stress when left for 20 seconds was measured. Compression speed is 3
0 mm / min. Five product samples were used for each of Examples 1, 2, and 3, and the average value was used as the compressive strength value.

In the foamed molded articles of the examples of the present invention, the moisture absorption rate in the comparison of the product characteristics of the foamed molded articles is as shown in Examples 1, 2 and 3 under the test environmental conditions: temperature of 40 ° C. and relative humidity of 90%. The product sample was evaluated by the water absorption rate after standing for 48 hours.

In the foamed molded articles of the examples of the present invention, the moisture absorption shrinkage resistance in the comparison of the product characteristics of the foamed molded articles is as follows: Test environment condition: temperature 40 ° C., relative humidity 90%.
With respect to the product samples of Examples 1, 2, and 3, the change in shrinkage after standing for 14 days was measured and evaluated by the shrinkage rate with respect to the dimension before the test.

In the foamed molded articles of the examples of the present invention, the elastic resilience in the comparison of the product characteristics of the foamed molded articles has a smooth glass plate obtained by cutting a product sample into a cylindrical body having a length of 50 mm and a diameter of about 15 mm. The sample was sandwiched between (50 * 50 * 2 mm), placed horizontally, and a load of 1 kg was applied to the center of the glass plate on the upper surface for 10 minutes, and then the load and the glass plate on the upper surface were removed. The restoration property after 30 minutes was evaluated, and the sample that was restored by 80% or more of the diameter was evaluated as good.

[0035]

The present invention is carried out in the form as described above and has the effects as described below.

The foamed molded article of the present invention and the method for producing the same are
Compared with the foamed molded products made of expanded polystyrene according to the conventional technology, the physical and mechanical strengths such as elasticity and compressive strength, and the water resistance such as hygroscopicity and hygroscopic shrinkage resistance are almost the same. It is possible to provide a foamed molded article that can secure the above, and has an effect that it can be used as a cushioning material such as a foamed sheet of packaging filler, a block, a tube, and the like.

Since the foamed molded product and the foamed molded product provided by the method for producing the same of the present invention contain a thermoplastic resin and a thermoplastic elastomer as the resin-based raw materials, no harmful gas is generated at the time of waste incineration, and Has the effect of not damaging.

[Brief description of drawings]

FIG. 1 is a process schematic view of a method for manufacturing a foamed molded product, showing an embodiment of the present invention.

FIG. 2 is a blending percentage by weight of raw materials of Examples 1, 2, and 3 with respect to various formulations in a method for producing a foamed molded product, showing an example of the present invention.

FIG. 3 shows an example of the present invention, in which the weight percentages of the product constituents in the foamed molded articles produced in Examples 1, 2, and 3 with respect to the above-mentioned various formulations are shown.

FIG. 4 shows an example of the present invention, which is an example of the foamed molded product of the present invention and the foamed molded product of the prior art manufactured in Examples 1, 2, and 3 for the above-mentioned various formulations. Product characteristics comparison with resin.

[Explanation of symbols]

1 mixer 2 extruder 3 cutting machine

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Claims (2)

[Claims] 1. A mixed raw material comprising starch and a thermoplastic resin as main raw materials, a thermoplastic elastomer added to the main raw materials, and an additive as a foaming aid,
In the mixing step (S1), an evenly mixed raw material mixture is secured using the mixer (1), and then in the extrusion step (S1).
In 2), the extruder (2) is used to knead, heat, and melt the raw material mixture under a predetermined high temperature and high pressure condition while further supplying water as a raw material, and then from the discharge opening of the extruder. It is discharged under normal pressure to form a foam molding continuous body, and then, in a cutting step (S3), the foam molding continuous body is cut into a desired size by using a cutting machine (3) and used as a cushioning material or the like. It is characterized by providing foamed molded products as products.
Method for producing foamed molded product. 2. A foamed body having starch and a thermoplastic resin as main constituents, a thermoplastic elastomer component, and an additive component as a foaming aid, and having a desired size. Foamed molded product.