JPH08183869A - Foam cushion and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To produce a cushioning material improved in biodegradability, dimensional stability and compressive strength by extruding a mixture of rice bran with polyvinyl alcohol and foaming the extrudate. CONSTITUTION: 50wt.% or above mixture comprising a natural starch and/or a modified starch as optional components and 50wt.% or below rice bran is mixed with 50wt.% or below polyvinyl alcohol and water to obtain a foaming material of a water content of 20wt.% or below. This material is fed into a single- or twin-screw extruder, kneaded at 120-200 deg.C, and extruded to obtain a foamed cushioning material having a bulk density of 5-50kg/m<3> , a modulus of 50% or above, a compressive strength of 400-1200g/cm, and a resistance to shrinkage due to moisture absorption of 90% or above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam cushioning body mainly used for various kinds of packaging and a method for producing the same.

[0002]

2. Description of the Related Art Polystyrene resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS as a foamable synthetic resin container, packaging material, and cushioning material for transportation.
A large amount of foams such as resins and polyurethane resins having a cushioning effect have been used.

For example, in expanded polystyrene, volatile liquid propane which does not dissolve polystyrene resin as a foaming agent and has a boiling point at or below the softening point of polystyrene resin,
Hydrocarbons such as butane, pentane, hexane, heptane,
Polystyrene resin mixed with alcohols, esters, ethers, ketones, halogenated hydrocarbons, etc.
Pre-expanded polystyrene beads are pre-expanded at a temperature of 0 to 110 ° C, then put into a mold and steam blown or heated at 100 to 130 ° C to cause secondary expansion and heat fusion of the beads to each other at the same time to obtain bulk density. Moldings of about 10 to 30 kg / m ³ are made.

However, there are the following problems. As foamable synthetic resin containers, packaging materials, and cushioning materials for transportation, a large amount of foamed materials such as polystyrene resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin, polyurethane resin, etc. that have a cushioning effect have been used. It was If these are discarded after use,
The incineration method has the disadvantages that it emits a significant amount of black smoke during combustion and that the combustion heat reaches 10,000 kcal, which causes early damage to the incinerator. When it is disposed of in a landfill, the foamable synthetic resin container and the packaging material are undegraded and left in their original shape indefinitely, and are therefore subject to waste pollution. It is also pointed out as an environmental pollutant in the sea, rivers, and lakes, where it is exposed as floating waste in its original form forever.

Therefore, like natural polymers, they are decomposed and assimilated by microorganisms in soil and water, incorporated into the natural material circulation system, and supplied with environmentally friendly packaging materials and transportation buffer materials that do not pollute the environment. That is an urgent issue.

[0006]

The problem to be solved by the present invention is to solve the above-mentioned conventional problems, and more specifically, it has biodegradability such as vegetable starch and is an edible grain itself. Instead, rice bran, which is a by-product of the grain refining process, is used to develop a new buffer material from a material that is friendly to the natural environment and can be assimilated by microorganisms in the natural environment.

[0007]

A foam cushioning body according to the present invention which can solve the above-mentioned problems comprises a foamed molded product of rice bran according to claim 1, wherein the foamed molded product contains polyvinyl alcohol. It is characterized by Further, in claim 2, the foamed molded product contains rice bran in a proportion of 50% by weight or more and polyvinyl alcohol in a proportion of 50% by weight or less.

According to a third aspect, the foamed molded product contains 50 to 80% by weight of rice bran and 50 to 20 of polyvinyl alcohol.
It is characterized in that it is contained in a weight percentage. In Claim 4, the bulk density is 5 to 60 kg / m ³ , the elastic modulus is at least 20%, the compressive strength is 200 to 1000 g / cm ² , and the moisture absorption shrinkage resistance is 70% or more.

According to a fifth aspect of the present invention, it comprises a foamed molded product of natural starch and / or modified starch and rice bran, and the mixture of natural starch and / or modified starch and rice bran contains rice bran in an amount of 50% by weight or less. At the same time, add 50% polyvinyl alcohol to the mixture.
It is characterized in that it is contained in a proportion of not more than wt%.

According to claim 6, the bulk density is 5 to 50 kg / m ³ ,
Elastic modulus at least 50%, compressive strength 400-120
It is characterized by 0 g / cm ² and moisture absorption shrinkage resistance of 90% or more. In claim 7, the total water content of the material is 20% by weight by using a single-screw or twin-screw extruder.
The following is characterized in that the foam molding is performed at a temperature of about 120 to 200 ° C.

According to the eighth aspect of the present invention, the material in the high temperature wet-expanded state that has left the extruder is subsequently subjected to a thermoforming operation.

[0012]

As described above, the present invention comprises a rice bran having biodegradability and a composition containing hydrophilic polyvinyl alcohol as a modifier for modifying the hardness, brittleness and foaming property of the rice bran. Which is a foaming buffer, and the method for producing the same is to provide the above-mentioned mixed composition with an extruder to give heat and moisture necessary for expansion and foaming,
Since foam molding is the basic principle, this foam molded product is almost completely decomposed in the natural environment and is assimilated by microorganisms in the natural environment to provide low density, elasticity and compressive strength that are environmentally friendly. It is possible to obtain the cushioning material.

At a low price and on the basis of effective use of resources,
An excellent cushioning molded article is obtained by using rice bran as a raw material and blending and using polyvinyl alcohol as a modified adhesive. As a manufacturing method, a simple molding method in which the materials rice bran and modifier polyvinyl alcohol are mixed and subjected to an extrusion molding machine to immediately obtain a foamed molded product, such as rope, hollow macaroni, flat sheet, etc. It is possible to efficiently and continuously produce molded products that have been cut into pieces.

The rice bran used as the main material in the present invention is mainly rice bran. Since the bran is a by-product, there is no precise specification in terms of composition components, but the use of a modifier and polyvinyl alcohol has the advantage that it can be used without any problems in terms of characteristics. Both of the rice bran and the rice bran in Table 1 below are in a category where they can be used.

[0015]

[Table 1]

As additives, insect repellents and rat repellents can be added as necessary or desired. Also,
Sodium phosphate, ammonium sulfate and the like can be added as the combustion retardant, and known compounds such as citric acid and ascorbic acid can be added as the antioxidant.

[0017]

EXAMPLES The physical properties of the foams obtained in the following examples were evaluated by the following methods. The method used to measure the bulk density of the bulk density material used micro glass beads and the weight of the material was calculated by measuring the weight of the glass beads required to replace the volume of the material.

Using a container (250 cm ³ ) of known volume, the fine glass beads (diameter 0.2) required to fill the container.
mm) and the density of the glass beads is calculated.

[0019]

[Equation 1]

The material is cut into 5 cm long cylinders and the weight of the material required to fill the container is measured. In that case, the material is packed so that there are few spaces between the material and the material and the container, and the material is not deformed. Next, glass beads are placed in the above space to fill the space, and the weight (increase) of the glass beads used for embedding is measured.

[0021]

[Equation 2]

Compressive strength When a squirrel cage jig is attached to an autograph manufactured by Shimadzu Corporation, the material is cut into a cylindrical body having a length of 20 mm, fully compressed (to a length of 10 mm) by 50% on a horizontal platen, and left for 20 seconds. Was measured. Compression speed is 30mm / min, 3 with new material
The measurement was performed once, and the average was taken as the value of the compressive strength. After the completion of the elastic modulus compression test, the length of the material was measured one minute later.

[0023]

(Equation 3)

The moisture- absorption shrinkage resistant material was allowed to stand for 14 days under the environmental conditions of 40 ° C. and RH 90%, and the dimensional change was measured. A constant temperature and humidity chamber attenuator manufactured by Advantech Toyo was used. Example 1 Rice bran starch (glucose 71.8%, crude protein 11.
9% by weight, 2.1% by weight of crude fat, 0.4% by weight of fiber, 1.1% by weight of ash, 12.7% by weight of water, using the content product), the blending addition amount of polyvinyl alcohol was changed to 2 Shaft meshing high shear screw type extruder (screw diameter 46m
m, die diameter 2.5 mmφ x 5 holes, heating 3 division band heater, barrel with ceramic heater, heating temperature 120 ~
Extrusion molding was performed at 200 ° C., a screw rotation speed of 300 rpm, a raw material supply rate of 20 to 30 kg / hr, and a total water content of 15 to 18% by weight. When the blending ratio of polyvinyl alcohol was 10% by weight, it was brittle and easily disintegrated. When about 20% by weight of polyvinyl alcohol was added, a molded product having a brittleness and no disintegration, a bulk density of about 14 kg / m ³ , a compressive strength and an elastic modulus was obtained.

Regarding the moisture absorption shrinkage resistance, a foamed molded product having a retention rate of 80% or more can be obtained by blending about 20% by weight or more of polyvinyl alcohol.

[0026]

[Table 2]

Example 2 Middle-bran starch, which has a higher fat content than that of white-bran starch, causes foaming inhibition and tends to be a hard and brittle foamed molded product. On the other hand, as shown in Table 3, 5
0% by weight or more and polyvinyl alcohol 50% by weight or less, compounded rice bran and white bran starch composition 50% by weight
The molded product obtained by the above and the compounding composition of 50% by weight or less of polyvinyl alcohol has a closed cell structure, a bulk density of about 12 to 15 kg / m ³ , an elastic modulus of 73 to 77%, and a compressive strength of 530 to 990 gr / cm ^2. Thus, a foamed molded product having a moisture absorption / shrinkage retention of 90% or more can be obtained.

The extruder conditions and operating conditions were the same as in Example 1.

[0029]

[Table 3]

The analytical composition of the used rice bran was as follows: glucose content: 58.8, protein: 14.7, fat content: 8.
7, fiber content: 2.6, ash content: 4.1, water content: 11.1% by weight Example 3 As shown in Table 4, modified cornstarch (modified starch) was mixed with 50% by weight or less of rice bran starch. A foamed molded product obtained from a compounded composition in which 50 wt% or more of polyvinyl alcohol is added to 50 wt% or less of polyvinyl alcohol improves a shrinkage defect due to moisture absorption of the modified cornstarch alone composition and has a low density closed cell structure. It showed satisfactory elastic modulus and compressive strength. Extruder conditions and operating conditions were the same as in Example 1.

The modified corn starch used is approximately 70%
Amylated corn starch was hydroxypropylated with 7% by weight propylene oxide and 3% by weight sodium sulfate was added.

[0032]

[Table 4]

[0033]

EFFECT OF THE INVENTION A mixed composition of rice bran and polyvinyl alcohol which is a hydrophilic resin, preferably 50 to 80 rice bran.
An extruded product obtained by extrusion from a blended composition of 50% by weight of polyvinyl alcohol and 50 to 20% by weight of polyvinyl alcohol is a foaming buffer having excellent properties for packaging, particularly as a protective cushioning material.

The foamed buffer according to the present invention comprises a starch type and / or a modified starch type (starch composition 90 to 10).
0% product), which is cheaper than low density foam molded products,
Under high humidity conditions, the foamed products do not shrink much and have excellent dimensional stability. Moreover, it is environmentally friendly, has low density, elasticity, and compressive strength, and has a biodegradability that is slower than the 100% natural starch product, but at least 50% by weight of rice bran starch. The blended composition contains at least about 4% by weight of crude fat when using the bran, and at least about 2% by weight of crude fat when using half and half bran. Molded products, in soil and water, in addition to the action of decomposing fats, decomposition by microorganisms,
Assimilation is promoted and it is put into the natural material circulation system and decomposes, so it is not exposed in its original form and the pollution after use as a buffer is eliminated.

Further, according to the manufacturing method of the present invention, it is possible to easily provide foam cushioning bodies of various forms.

Claims (8)

[Claims] 1. A foam cushioning body comprising a foam molded product of rice bran, wherein the foam molded product contains polyvinyl alcohol. 2. The foam cushioning body according to claim 1, wherein the foamed molded product contains rice bran in an amount of 50% by weight or more and polyvinyl alcohol in an amount of 50% by weight or less. 3. The foam cushioning body according to claim 2, wherein the foamed molded product contains rice bran in an amount of 50 to 80% by weight and polyvinyl alcohol in an amount of 50 to 20% by weight. 4. The foamed buffer according to claim 1, which has a bulk density of 5 to 60 kg / m ³ , an elastic modulus of at least 20%, a compressive strength of 200 to 1000 g / cm ² , and a moisture absorption shrinkage resistance of 70% or more. . 5. A foamed molded product of natural starch and / or modified starch and rice bran, wherein the mixture of natural starch and / or modified starch and rice bran contains rice bran in a proportion of 50% by weight or less, and A foaming buffer containing polyvinyl alcohol in a proportion of 50% by weight or less with respect to the mixture. 6. The foamed cushion according to claim 5, which has a bulk density of 5 to 50 kg / m ³ , an elastic modulus of at least 50%, a compressive strength of 400 to 1200 g / cm ² , and a moisture absorption shrinkage resistance of 90% or more. . 7. A foamed buffer body, characterized by using a single-screw or twin-screw extruder to make the total water content of the material 20% by weight or less and foaming at a temperature of about 120 to 200 ° C. Method. 8. The method for producing a foam cushioning body according to claim 4, wherein a thermoforming operation is subsequently applied to the material in the high temperature wet expanded state that has left the extruder.