JP3439239B2 - Edible biodegradable buffer and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

[Industrial applications]

[0002] The present invention relates to an edible biodegradable cushioning material and a method for producing the same, and more specifically, using starch as a raw material,
The present invention relates to an edible biodegradable cushioning material which has excellent elasticity, is edible and biodegradable, and can be used as a cushioning material for a polystyrene foam substitute.

Further, the edible biodegradable cushioning material according to the present invention can be used as a livestock feed as well as a compost after being used as a cushioning material.

[0004]

[Prior Art and Problems to be Solved by the Invention]

At present, pollution caused by synthetic plastics, which is also used as a raw material for cushioning materials, occupies a major position in environmental problems.

Although a recycling movement of synthetic plastics is also being carried out, the recovery rate is low, and it is difficult to completely sort the recovered plastics due to the large number of types of synthetic plastics. Is.

As one means for solving this problem, a biodegradable plastic that has been decomposed by microorganisms and returned to nature has appeared.

Several types of cushioning materials have been developed using starch as a raw material. However, in order to retain the physical properties of the cushioning materials, all of them are made of synthetic plastic material for starch and are quite acceptable. It cannot be said that it is dietary.

Therefore, at present, there is no known biodegradable and edible cushioning material.

[0010] Heretofore, as a technique related to a starch-based foam, Japanese Patent Application Laid-Open No. 50-83469, Japanese Patent Publication No. 53-39902, and Japanese Patent Publication No. 59-5.
There are those disclosed in Japanese Patent Application Laid-Open No. 00251 and Japanese Patent Application Laid-Open Nos. 2-298525 and 5-39377.

Among these, Japanese Unexamined Patent Publication No. 50-83469 discloses amylose as a raw material, and Japanese Unexamined Patent Publication No. 2-298525 discloses one in which starch containing 45% or more amylose is used as a raw material.

[0012] In the case of amylose, the molecular structure has many straight-chain portions and the film-forming property is relatively good, and when extruded at a higher temperature than the extruder, the amylose molecules are easily arranged and organized in the extrusion direction. It is considered that a foam having a specific elasticity is obtained.

However, in the case of ordinary starch, the amylose content is about 20 to 27%, and only the cornstarch separated and purified from high amylose corn has an amylose content of 45% or more.

However, in order to use high amylose for this purpose, the raw material price is high and it is not practical.

Japanese Patent Publication No. 53-39902 discloses a method in which an organic solvent having a boiling point of 100 ° C. or less is used as a foaming agent.

When such an organic solvent is used, bubbles are generated inside the extruder barrel during extrusion of the extruder, and it becomes difficult for the gelatinized starch film to retain the bubbles when discharged from the die, resulting in good foaming. Hard to get a body.

Further, when foaming occurs inside the barrel, the pressure fluctuates due to the expansion and contraction of gas, the discharge speed becomes unstable, and the shape of the foam changes and becomes non-uniform.

In Japanese Patent Publication No. 59-500251, a foam produced by using a carbonate, an organic or inorganic acid or an acid reaction substance, and an acid supply substance as a gas generating and expanding agent, and extruding by heating with an extruder at 60 to 220 ° C. Is disclosed.

A starch foam can be produced only under the conditions described here, but the resulting foam has poor elasticity and easily collapses, so that it cannot be used as a cushioning material.

Further, in Japanese Unexamined Patent Publication No. 5-39377, the gas generating expander used in the above-mentioned Japanese Patent Publication No. 53-39902 and Japanese Patent Publication No. 59-500251 is denied, and heating gas generation is performed. Disclosed is the use of a water-insoluble foam control agent of the type.

Examples of the bubble control agent include azo-based, hydrazine-based, triazole-based, N-nitroso-based organic foaming agents, inorganic foaming agents such as ammonium bicarbonate, sodium bicarbonate and potassium bicarbonate, and butane except alcohol-based foaming agents. , Volatile compounds containing hydrocarbons such as pentane are mentioned.

These bubble regulators are foaming agents usually used in synthetic plastics and are disclosed in Japanese Patent Publication No. 59-50025.
The publication 1 has the same description.

According to Japanese Patent Application Laid-Open No. 5-39377, the gas generating and expanding agent in Japanese Patent Publication No. 59-500251 is a mixture of a metal carbonate and an organic acid, and since foaming has no temperature dependence in the extruder. It is said that the target foam cannot be obtained by foaming regardless of the heating temperature.

However, the foaming of the carbonate is largely dependent on the pH of the paste liquid which is melted in the extruder, and the foaming is performed at the time of die discharge by appropriately setting the amounts of the carbonate and the organic acid. Is sufficiently possible, and Japanese Patent Laid-Open No. 5-39
Equivalent products can be obtained within the range of the technical contents described in Japanese Patent No. 377.

On the other hand, although excellent results are described for the effects of the invention described in Japanese Patent Application Laid-Open No. 5-39377, there is no description about the conditions and technical contents leading to them, and the results are shown in Table 59 It does not go beyond the scope of the technology described in Japanese Patent Publication No. 500251.

Therefore, according to the technical contents described in JP-A-5-39377, a starch foam can be obtained,
The desired elastic cushioning material cannot be obtained.

Azo-based organic foaming agents, which are foamed by heating, foam in the barrel of the extruder and cannot be resisted even by the internal pressure of the extruder, and are broken into bubbles, resulting in a powdery state. It is discharged and a good foam cannot be obtained.

[0028]

[Means for Solving the Problems]

It has been found that an elastic and highly flexible cushioning material cannot be obtained only by the conditions found in the prior art.

Therefore, the inventors of the present invention determined that it was necessary to search for a more unknown and detailed condition design in order to obtain the intended cushioning material, and conducted extensive studies to find the condition.

Further, as a result of studying conventional techniques, the present inventors questioned why high-amylose starch gives a relatively good foam but ordinary starch does not give a good product. In addition, when polyvinyl alcohol (PVA) was mixed and subjected to an extruder treatment, a very good product was obtained, but there was a question as to why.

It is considered that this is due to the structure of the starch molecule. Specifically, in the case of high amylose, there are many straight-chain moieties, and the molecules tend to be oriented at the time of extrusion from the extruder, and the straight-chain molecules in the extrusion direction. It is considered that when the cells are lined up, they are organized and the film property of the bubble film surface is strengthened to obtain elasticity. In addition, since it is considered that making bubbles fine is also an element that imparts elasticity, the raw materials, additives, extruder operating conditions, etc. were examined to satisfy these elements.

When only the starch is extruded under normal extruder conditions, a starch foam having a finished appearance can be obtained, but its bubbles are large, and "air hurt" or "scratch".
Swelled like (rice cracker), brittle against external pressure, elastic,
It becomes inflexible.

As a result of examining conditions for imparting elasticity and flexibility to this foam, it was considered necessary to satisfy the following factors.

1. Increase the total volume of bubbles. 2. Individual bubbles are miniaturized to reduce the volume of single bubbles. 3. Moreover, the above 1. In order to satisfy, the number of bubbles is increased. 4. When extruded from the extruder, the starch molecules are oriented and organized to strengthen the film strength of the bubble film surface.

The above 1. , 2. , 3. For the factors of
The selection of additives and the setting of extruder operating conditions were investigated.

The above 4. Is the core of the present invention, and this has been thoroughly studied.

High-amylose cornstarch with high amylose content (amylose content = 60%) and normal cornstarch (amylose content = 25%) were extruded under normal extruder conditions without additives to obtain starch foaming. There was a considerable difference in the physical properties.

High amylose starch gave relatively good foams, whereas ordinary starch gave brittle foams with no elasticity.

It is considered that this is because in the case of high amylose, the molecule has many linear portions and the molecular orientation is easy.

Therefore, even in ordinary starch, if the extruder conditions are set so that the molecular orientation is possible, it is possible that a starch foam equivalent to that in the case of high amylose may be produced, and earnest research is conducted. Continued.

That is, by making the discharge speed from the die of the extruder as high as possible and making the length of the die hole (hole length) long, the flow velocity difference between the center portion of the discharged matter and the die wall surface portion. It is considered that the longitudinal molecular orientation is generated by the mutual pulling and the orientation causes elasticity of the starch foam.

When the starch is subjected to the extruder treatment, when it is injected from the die at a temperature of 100 ° C. or more under normal conditions (the additives other than water are not used, the treatment amount is moderate), then immediately after the die is discharged. 1-2 cm is not swelled yet and is in a transparent state.

After that, the water inside is vaporized to become water vapor, which expands in the direction perpendicular to the discharge direction.

In this case, the swelling volume is large and good, but the elasticity is poor and the film is in the form of "hail" or "scratch".

However, by adding an appropriate expanding agent, it is possible to increase the discharge speed because the inside of the die is expanded in the injection direction at the same time as the pressure is decreased, and by doing so, the foam is finely foamed and the elasticity is improved. There was found.

Therefore, the following conditions were considered as the operating conditions of the extruder.

1. Make the extrusion speed from the extruder as fast as possible. 2. Increase the length of the die hole. 3. The discharge speed is further increased by foaming inside the die and increasing the volume at the time of discharging from the die. 4. Selection and amount of foaming agent for foaming inside the die. 5. Selection of auxiliary additives and determination of amounts for smoother operation under the above conditions.

As a result, in order to increase the extrusion speed of the extruder, it is necessary to increase the feed amount to the limit of the normal device capacity and to minimize the opening area of the die hole.

At the same time, a foaming agent such as baking powder is used to reduce the pressure when passing through the die, and at the same time, foam in the die to accelerate discharge from the die opening.

In order to secure the feed amount, it is necessary to reduce the extruder load, and the purpose can be achieved by mixing vegetable oil such as soybean oil.

In order to obtain as many fine bubbles as possible, an emulsifier such as sucrose fatty acid ester is added to improve the dispersibility of the mixed fats and oils.

Only when the above conditions were satisfied, the discharge speed from the extruder was secured, and a starch foam having good elasticity and flexibility was successfully obtained, and the present invention was completed.

That is, the means for solving the problems of the present invention are as follows.

First, a foaming agent was added to starch so that the pore length was 5
100 with an extruder equipped with a ~ 50mm die
An edible biodegradable cushioning material obtained by heating to ˜200 ° C., melting, and extruding in an expanded state from an extruder die at a discharge rate of 100 to 400 m / min.

Second, the foaming agent is added to the starch in an amount of 0.01 to
5%, fat and oil 0.1 to 20%, and emulsifier 0.01 to
Add 5%, heat to 100-200 ℃ with an extruder equipped with a die with a hole length of 5-50 mm, melt, and expand 100-400 m from the extruder die.
An edible biodegradable cushioning material obtained by extruding at a discharge rate of 1 minute.

Thirdly, a foaming agent was added to starch so that the pore length was 5
100 with an extruder equipped with a ~ 50mm die
A method for producing an edible biodegradable cushioning material, which comprises heating to ~ 200 ° C, melting, and extruding in an expanded state from a die of an extruder at a discharge rate of 100 to 400 m / min.

Fourthly, the amount of the foaming agent is 0.01 to 0.01 with respect to the starch.
5%, fat and oil 0.1 to 20%, and emulsifier 0.01 to
Add 5%, heat to 100-200 ℃ with an extruder equipped with a die with a hole length of 5-50 mm, melt, and expand 100-400 m from the extruder die.
A method for producing an edible biodegradable cushioning material, which is produced by extruding at a discharge rate of 1 / min.

Here, as the foaming agent, in addition to commercially available baking powder, sodium hydrogen carbonate, baking alum,
It is also possible to use a mixture of primary lime phosphate.

More specifically, the amount of the foaming agent added is 0.01 to 5%, which varies depending on the kind of the foaming agent, but when a commercially available baking powder is used, it is preferably 1%.
~ 2%, the amount of fat added is 0.1 to 20%, preferably 5
-10%, and the amount of the emulsifier added is 0.01-5%, preferably 0.1-1%.

In addition, addition of calcium carbonate, talc, diatomaceous earth or the like is effective in order to stably generate a large number of fine bubbles, and a more stable foam can be obtained.

Further, the addition amount of calcium carbonate, talc, diatomaceous earth or the like can be added up to 20% with respect to starch.

As the condition of the extruder, a biaxial type is preferable in order to increase the conveying speed, and the opening area of the die hole is 100 to 400 m / min, preferably 150 to 350 m / min when the discharge speed is in the expanded state. Set to.

The temperature of the barrel and the contents is not particularly limited, but may be in the range of boiling point of 100 ° C to carbonization coloring of 200 ° C, preferably 110 to 160 ° C.

The discharge pressure of the die has a close relationship with the discharge speed and is automatically determined, and its numerical value is 50.
~ 150 kg / cm ² .

In order to satisfy the above conditions, it is necessary to minimize the mechanical load, and by using oils and fats and emulsifiers within the above-mentioned use amount ranges, the feed amount can be further increased, resulting in expansion and foaming. The structure of the body membrane surface becomes good, and the flexibility and elasticity of the expanded product can be satisfied as a cushioning material only by adopting such conditions.

[0067]

【Example】

First, an extruder used for carrying out the present invention will be described with reference to the schematic view of the extruder shown in FIG.

The extruder used in this embodiment is
Alpha riser α-50 made by Suehiro EPM Co., Ltd.
Type (screw diameter = 68 mmφ), which is composed of a biaxial screw 1, a barrel 2, a die 3, a heating coil and cooling jacket 4, a drive motor 5, and a feeder 6.
A liquid injection port 7 is provided in the middle of the barrel 2, and a cutter 8 is attached to the discharge port of the die 3.

The structure of the twin screw 1 of the extruder was a forward (forward) ball type, and a partial reverse (reverse direction) cut flight type was inserted in the final stage.

As the die 3, only one die having a diameter of 3 mm and a hole length of 12 mm was used.

Next, the operation of the extruder will be described.

The raw material is continuously supplied from the hopper through the feeder 6 into the barrel 2 of the extruder.

The raw material continuously supplied into the barrel 2 is transferred forward by the twin-screw screw 1.

When liquid injection is required, the liquid is injected from the liquid injection port 7 in the middle of the barrel 2 by a metering pump (not shown).

The transferred raw material is mechanically processed by the twin-screw screw 1 according to the processing conditions, and at the same time, heat-treated by the heating coil and the cooling jacket 4.

The treated raw material is pressurized and discharged from the die 3 at the tip and cut into an appropriate size by the rotary cutter 8 to form a cocoon-like expanded product.

Hereinafter, the edible biodegradable cushioning material according to the present invention was prepared by using the above extruder with a screw rotation speed of 25.
An example manufactured by operating at 0 rpm will be described.

Corn starch was used as the raw material starch, the starch feed rate was 70 kg / h, and the water addition rate was 3.5 liters /
Under the conditions of h, as shown in Table 1, the use amount of the additive was changed to 8 ways, and the examples were performed.

The baking powders shown in Table 1 are
It is manufactured by Inoue Suke Shoten Co., Ltd. and contains the following components.

Sodium hydrogen carbonate 27.0%: d-sodium hydrogen tartrate 10.0%: fumaric acid monosodium 10.0%: roasted alum 23.0%: sucrose fatty acid ester 0.8%

The compounding foaming agent used in Example 6 is based on the following components.

Sodium hydrogen carbonate 43%: Baked alum 3
0%: Primary lime phosphate 27%

The puffed product obtained in each of the examples was cut by the cutter 8 at the time of discharge to form a cocoon ball shape.

Regarding the cocoon-ball-shaped puffed products obtained in each Example,
In addition to obtaining the bulk density and elastic modulus, observation with the naked eye was performed.
Sensory tests were performed by human panelists on three items: swelling, elasticity, and dusting.

The bulk density was calculated using the following formula.

Bulk density (g / l) = [length 15 cm, width 1
Weight of sample filled in box with 5 cm and depth of 20 cm] /
[Volume of a box 15 cm long, 15 cm wide, 20 cm deep]

The elastic modulus is measured by the creep meter [Leonar R
E-3305] A sample piece cut into 10 mm was manufactured by Sanden Co., Ltd. and 0.5 mm with a plunger having a diameter of 30 mm.
At a rate of / sec, the sample piece height after 1 minute of compression after release to 50% of the original height was measured and calculated using the formula:

Elastic modulus (%) = {[height of sample piece after 1 minute−50% height of sample piece] / [height of sample piece before compression−50% height of sample piece] ]} × 100

The sensory test was carried out by the 5-point evaluation method as follows.

As for the swelling property, the swelling state, particularly the volume per piece and the state of bubbles were observed with the naked eye.

The elasticity was judged by the feel when touched by the hand.

As for the powder standing, the state in which the powder was not generated was observed by observing the powder generation state due to the way the powder was crushed by hand.

Regarding the result of the sensory test, 1 = bad, 2
= Slightly bad, 3 = normal, 4 = somewhat good, 5 = good, with 5 levels as 5 grades, each of the 10 panelists expressed 1 to 5 points, and statistically processed the results. expressed.

For each example, the temperature of the die plate and the tip barrel and the pressure of the die plate were measured, and the discharge rate was calculated by the following equation.

Discharge speed (m / min) = [expanded tip length (cm) × cutter rotation speed (rpm) × blade number] /
100

The above results are shown in Table 1.

[0098]

[Table 1]

[0099]

[Comparative example]

Table 2 is basically the same as the above embodiment.
As shown in Comparative Example 1, the amount of starch feed, the amount of water added, the amount of additive used, the type of die, etc.
In Comparative Example 6, the physical properties of the products obtained in each Comparative Example were measured and the discharge speed was determined in the same manner as in the above Examples.

The results are shown in Table 2.

[0102]

[Table 2]

[0103]

【The invention's effect】

According to the present invention, the flexibility and elasticity are excellent,
It is possible to obtain an edible biodegradable cushioning material which is edible and biodegradable and can be used as a cushioning material for a polystyrene foam substitute.

The edible biodegradable cushioning material according to the present invention is
After being used as a cushioning material, it can be used not only for composting but also as feed for livestock, which gives a solution to environmental problems such as plastic pollution.

[Brief description of drawings]

FIG. 1 Schematic diagram of the extruder

[Explanation of symbols]

1 twin screw 2 barrels 3 dies 4 Heating coil and cooling jacket 5 drive motor 6 feeder 7 Injection port 8 cutter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI // B29K 105: 04 B65D 81/04 (56) References JP 62-239975 (JP, A) JP 4-126734 (JP, A) JP-A-1-97615 (JP, A) JP-A-5-39377 (JP, A) JP-A-5-50493 (JP, A) JP-A-1-135620 (JP, A) Kai 50-83469 (JP, A) JP 2-298525 (JP, A) JP 59-64316 (JP, A) JP 53-39902 (JP, B1) JP 59-500251 ( (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 47/00-47/96 B65D 81/107 C08K 3/00-13/08 C08L 1/00-101/16 C08J 9 / 00-9/42

Claims (4)

(57) [Claims] 1. A foaming agent is added to starch so that the pore length is 5 to 50.
Extruder equipped with mm die 100 to 20
An edible biodegradable buffer material obtained by heating to 0 ° C., melting, and extruding in an expanded state from a die of an extruder at a discharge speed of 100 to 400 m / min. 2. A foaming agent is 0.01 to 5% with respect to starch,
Add 0.1 to 20% of oil and fat and 0.01 to 5% of emulsifier, heat with an extruder equipped with a die with a hole length of 5 to 50 mm to 100 to 200 ° C., melt and extrude in an expanded state. An edible biodegradable cushioning material obtained by extruding from a die of a ruder at a discharge speed of 100 to 400 m / min. 3. A foaming agent is added to starch so that the pore length is 5 to 50.
Extruder equipped with mm die 100 to 20
A method for producing an edible biodegradable cushioning material, which is produced by heating to 0 ° C., melting, and extruding in an expanded state from a die of an extruder at a discharge rate of 100 to 400 m / min. 4. The foaming agent is 0.01 to 5% with respect to starch,
Add 0.1 to 20% of oil and fat and 0.01 to 5% of emulsifier, heat with an extruder equipped with a die with a hole length of 5 to 50 mm to 100 to 200 ° C., melt and extrude in an expanded state. A method for producing an edible biodegradable cushioning material produced by extrusion from a die of a ruder at a discharge speed of 100 to 400 m / min.