JPH093334A - Thermoplastic material obtained from protein, its molded item, and their production - Google Patents

Abstract

PURPOSE: To obtain a biodegradable, environmentally friendly thermoplastic material by thermally treating a mixture of protein and an org. polyhydroxy compd. under specified conditions. CONSTITUTION: This material, having a tensile strength of 10-300kg/cm<2> , is obtd. by pressing a mixture of protein and an org. polyhydroxy compd. in an open system at 100 deg.C or higher. Pref. examples of the polyhydroxy compd. are glycerin, ethylene glycol, diethylene glycol, and polyethylene glycol. Substituting a part of the polyhydroxy compd. with water is also pref.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic material obtained from a protein, a molded article thereof, and a method for producing the same. More specifically, the present invention relates to a material obtained by heat-treating a protein under predetermined conditions. The present invention relates to a material having thermoplasticity similar to that of a general thermoplastic resin, a molded article made of such a material, and a method for producing them.

[0002]

2. Description of the Related Art Conventionally, a large amount of protein has been discarded as an industrial waste from a food processing company without being effectively used. For example, most of the residues obtained by processing seafood, birds and animals into foods are discarded as industrial wastes, and a method for effective use thereof is required.

Therefore, for example, Japanese Patent Application No. 5-332484.
It is proposed to obtain a thermoplastic material by heating a protein in the presence of water and / or an organic hydroxy compound in a closed system at a temperature above 100 ° C. for a certain period of time. However, since this material is manufactured in a relatively small-scale closed system, there is room for improvement in expanding the scale and simplifying the manufacturing method.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention aim to improve the method for producing a thermoplastic material from a protein and to develop a thermoplastic material having biodegradability with the aim of effectively utilizing the protein. As a result of diligent research, it was found that even if the protein is heat-treated under a predetermined condition in an open system rather than in a closed system, it has almost the same thermoplasticity as a general thermoplastic resin and can be a molded article, The present invention has been achieved.

Since the thermoplastic material according to the present invention is derived from a protein, it is originally not only excellent in safety and hygiene but also has biodegradability which naturally decomposes even when it is left unattended. For example, a molded product made of an environmentally friendly thermoplastic material such as a disposable container or a cap can be used.

[0006] Therefore, the present invention is a thermoplastic material using protein as a raw material, which has thermoplasticity similar to general thermoplastic resins, molded articles made of such materials, and methods for producing them. The purpose is to provide.

[0007]

The thermoplastic material according to the present invention has a tensile strength of 10 to 300 kg / cm obtained by pressurizing a mixture of protein and an organic polyhydroxy compound at a temperature of 100 ° C. or higher in an open system. It is in the range of ² . A molded product made of such a material according to the present invention can be obtained by thermoforming the thermoplastic material.

First, a method of manufacturing a thermoplastic material according to the present invention will be described. In the present invention, the protein used as a raw material typically includes soybean protein, protein albumin, Zein, casein, etc., but is not limited to these, and other various proteins can be used. Can be used. For example, these proteins can be obtained from food waste, processed blood of animals and fish, casein precipitation residue of milk, and the like.

When dried protein is used as a raw material, usually 20 to 95% by weight of such protein and 80 to 5% by weight of organic polyhydroxy compound are mixed and stirred to form a uniform protein paste. Prepared and opened it 1
The thermoplastic material according to the present invention is obtained by heating at a temperature exceeding 00 ° C., for example, by press molding. Here, in the preparation of the protein paste, the amount of the organic polyhydroxy compound is preferably 10 to 70% by weight, particularly preferably 15 to 50% by weight.

When the amount of protein in the protein paste is too small, the thermoplastic material obtained is usually soft and it may be difficult to maintain a certain shape as it is.
On the other hand, when the amount of protein is too large, in the obtained material, the action of the organic polyhydroxy compound as a plasticizer may be insufficient, and the material may not have sufficient thermoplasticity. By setting the amount of the organic polyvalent hydroxy compound to the protein within the above range, the tensile strength is 10 to 300.
Thermoplastic materials in the range of kg / cm ² can be obtained.

In the present invention, specific examples of the organic polyhydric hydroxy compound include, for example, glycerin, diglycerin, trimethylolpropane, pentaerythritol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, sorbitol, sorbitan, mannitol. Examples thereof include aliphatic polyhydric alcohols such as maltitol, sucrose and polyethylene glycol, and polyhydric phenol compounds such as resorcin or aromatic polyhydric hydroxy compounds. Among these, glycerin, ethylene glycol, diethylene glycol or polyethylene glycol is particularly preferable.

According to the present invention, water can be used in place of a part of the organic polyhydroxy compound in the production of the thermoplastic material, if necessary. As described above, when water is used in place of a part of the organic polyhydroxy compound, the amount of water is 50% of that of the organic polyhydroxy compound used in order to prevent brittleness of the molded product due to evaporation after molding. It is preferably in the range of not more than 30% by weight, preferably not more than 30% by weight.

Therefore, the thermoplastic material according to the present invention and the molded article obtained from the thermoplastic material can be obtained, as described above, by containing an organic polyhydric hydroxy compound and, in some cases, water together with the organic polyhydric hydroxy compound. However, if it contains a large amount of water, if it is left in an air atmosphere for a long time, the water may evaporate over time and the hardness may increase.In some cases, it has poor strength and is easily cracked. Will be lacking.

The thermoplastic material obtained from the protein according to the present invention is a 100% protein paste in which the content of the organic polyhydroxy compound (and water in some cases) is appropriately adjusted.
It can be produced by pressurizing at a temperature exceeding 0 ° C., for example, press molding. The mold for press molding is not particularly limited, and for example, a mold having a gap of 0.3 to 1.0 mm can be used. Press molding usually consists of hot press molding and cooling press molding.

First, hot press molding is performed as follows. After preheating the protein paste under atmospheric pressure at a predetermined temperature for about 1 to 15 minutes, while maintaining this temperature,
In order to degas the gas generated from the protein paste,
The pressure is increased to a predetermined pressing pressure while defoaming. This defoaming time is usually about 0.5 to 1 minute. In order to effectively perform defoaming during this pressurizing operation, the pressure may be increased or decreased while the pressure is being changed.

In this way, when the predetermined pressure is reached, heating and press molding is carried out while maintaining the predetermined temperature for a certain period of time under this pressure, and then depressurized to atmospheric pressure to obtain from the mold. Take out the molded product. The preheating temperature and the press molding temperature may be usually the same temperature, or the preheating temperature may be set lower than the press molding temperature and the temperature may be raised to the press molding temperature during the pressurizing operation.

Next, in the cooling press molding, the warm depressurized molding obtained in the above heating press molding is immediately attached to another press molding machine, pressurized to a predetermined pressure, and usually held for several minutes. Usually, it takes several minutes to cool to normal temperature under pressure and depressurize to obtain the sheet-shaped thermoplastic material according to the present invention. The molding pressure in this cold press molding may be the same as the pressure in the hot pressing step.

However, in the production of the thermoplastic material according to the present invention, the above cooling press molding is not always necessary, and it may be combined with the heating press molding. Also,
Both press moldings are preferably performed under an inert gas atmosphere, for example, a nitrogen atmosphere.

In the present invention, the preheating temperature and the molding temperature are usually 100 to 200 ° C., preferably 110 to 1
The temperature is 90 ° C., most preferably 130 to 170 ° C., and the pressing time is usually about 1 to 100 minutes, preferably about 1 to 10 minutes. The pressurizing condition in press molding may be atmospheric pressure or more, but is usually 5 kg / cm ² or more, preferably 50 kg / cm ²
That is all. The pressing conditions in the cold press molding are usually the same as those in the hot press molding, but they do not necessarily have to be the same.

[0020]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. The raw materials used in the following examples are as follows. Soy protein: New Fuji Pro SE Casein: Reagent Casein Na: Reagent Zein: Reagent Glycerin: Special grade reagent Diethylene glycol: First grade reagent

Examples 1-8 show examples of the production of thermoplastic materials according to the invention. In these, the protein paste was heat press-molded by a press molding machine equipped with a mold of 10 cm × 10 cm × 0.5 mm and then cold press-molded to obtain a sheet-shaped thermoplastic material. The tensile strength of the obtained thermoplastic material was measured under the following measurement conditions.

Measuring instrument: Model 4501 manufactured by Instron Co., Ltd. Measuring condition: 25 ° C., pulling speed 30 mm / min Measuring sample: Distance between chucks 30 mm, sample width 5 mm

Example 1 9 g of soybean protein and 3 g of glycerin were mixed and stirred well, and then preheated for 5 minutes with a press molding machine equipped with the above mold.
Defoaming for 1 minute, press temperature 150 ℃, press pressure 100kg /
Heat press molding represented by cm ² and press time of 5 minutes was performed, and then cooling press molding was performed for 3 minutes to obtain a yellow-orange, almost transparent sheet-shaped thermoplastic material.
The tensile strength of this material was 170 kg / cm ² .

Example 2 Heating and cooling press molding were performed in the same manner as in Example 1 except that 8 g of soybean protein and 4 g of glycerin were used to obtain a sheet-like thermoplastic material having a tensile strength of 112 kg / cm ^2. It was

Example 3 Heating and cooling press molding were performed in the same manner as in Example 1 except that 6 g of soybean protein and 6 g of glycerin were used to obtain a sheet-like thermoplastic material having a tensile strength of 56 kg / cm ^2. It was

Example 4 Heating and cooling press molding were performed in the same manner as in Example 1 except that 4 g of soybean protein and 8 g of glycerin were used to obtain a sheet-like thermoplastic material having a tensile strength of 25 kg / cm ^2. It was

Example 5 Zein (6 g) and glycerin (6 g) were mixed and stirred well, and then preheated for 7 minutes, defoaming for 1 minute, press temperature of 150 ° C., press pressure of 100 kg / cm, using a press molding machine equipped with the above mold.
² , hot press molding was carried out under the condition of pressing time of 5 minutes, and then cooling press was carried out for 3 minutes to obtain a yellow sheet-shaped thermoplastic material. The tensile strength of this material is 119
kg / cm ² .

Example 6 8 g of casein and 4 g of glycerin were mixed and stirred well, and then preheated for 5 minutes, defoaming for 1 minute, press temperature 150 ° C., press pressure 100 kg / in a press molding machine equipped with the above mold. cm
² , hot press molding was carried out under the condition of pressing time of 5 minutes, and then cooling press was carried out for 3 minutes to obtain a light yellow sheet-like thermoplastic material. The tensile strength of this material is 92
kg / cm ² .

Example 7 8 g of casein Na and 4 g of glycerin were mixed and stirred well, and then preheated 5 with a press molding machine equipped with the above mold.
Min, defoaming 1 min, press temperature 150 ° C, press pressure 100
Heat press molding was carried out under the conditions of kg / cm ² and pressing time of 5 minutes, and then cooling press was carried out for 3 minutes to obtain a light yellow sheet-shaped thermoplastic material. The tensile strength of this material was 77 kg / cm ² .

Example 8 8 g of soybean protein and 4 g of diethylene glycol were mixed,
After stirring well, with a press molding machine equipped with the mold,
Preheating 5 minutes, defoaming 1 minute, press temperature 150 ° C., press pressure 100 kg / cm ² , press time 5 minutes, hot press molding is performed, and then cooling press is performed for 3 minutes,
A pale yellow sheet-shaped thermoplastic material was obtained. The tensile strength of this material was 100 kg / cm ² .

When a part of each of the sheet-like thermoplastic materials obtained as described above was buried in soil, there were some differences, but in all cases, after one month, more than half decomposed, Some of them had almost no shape.

COMPARATIVE EXAMPLE 1 8 g of casein and 4 g of distilled water were mixed and stirred well,
Using a press molding machine equipped with the mold, preheat 5 minutes, defoam 1
Min, press temperature 150 ° C, press pressure 100 kg / cm ² ,
Hot press molding was carried out under the condition of pressing time of 5 minutes, and then cooling press was carried out for 3 minutes to obtain a sheet material. Bubbles were present on the entire sheet of this material, and when it was left to stand, water transpirationd, causing no strength and cracking.

Comparative Example 2 Zein 6g and distilled water 6g were mixed and stirred well.
It was difficult to obtain a uniform paste. Preheat the obtained paste with a press molding machine equipped with the above-mentioned mold 5
Min, defoaming 1 min, press temperature 150 ° C, press pressure 100
Heat press molding was performed under the conditions of kg / cm ² and a pressing time of 5 minutes, and then a cooling press was performed for 3 minutes to obtain a sheet-shaped material. This material has bubbles throughout the sheet,
When left unattended, the water vaporized and was not strong enough to break.

Comparative Example 3 When soybean protein was used as the protein, the same procedure as in Comparative Examples 1 and 2 was carried out. When the sheet-shaped material obtained was left to stand, water was evaporated and the sheet-like material had no strength and cracked. I got it.

[0035]

INDUSTRIAL APPLICABILITY According to the present invention, a material having thermoplasticity can be obtained from many kinds of proteins. Proteins discharged as industrial waste by food processing companies and the like, for example, proteins in wastes discarded as residues after processing seafood, birds and animals into food, by treating according to the production method of the present invention, It is possible to obtain a thermoplastic protein having a hardness capable of being molded into a medical capsule, a disposable container, a cap or the like. Since such a protein-derived thermoplastic material according to the present invention is biodegradable, it naturally decomposes even if left unused after use, so that an environmentally friendly molded article can be provided.

Claims (7)

[Claims] 1. A thermoplastic material having a tensile strength in the range of 10 to 300 kg / cm ² obtained by pressurizing a mixture of a protein and an organic polyhydroxy compound at a temperature of 100 ° C. or higher in an open system. 2. An organic polyhydroxy compound is glycerin,
The thermoplastic material according to claim 1, which is at least one selected from ethylene glycol, diethylene glycol, and polyethylene glycol. 3. Production of a thermoplastic material having a tensile strength in the range of 10 to 300 kg / cm ^{2 which} is characterized by pressurizing a mixture of a protein and an organic polyhydroxy compound at a temperature of 100 ° C. or higher in an open system. Method. 4. The method for producing a thermoplastic material according to claim 3, wherein water is used in place of a part of the organic polyhydroxy compound. 5. The organic polyhydroxy compound is glycerin,
The method for producing a thermoplastic material according to claim 3, which is at least one selected from ethylene glycol, diethylene glycol, and polyethylene glycol. 6. A method for producing a biodegradable thermoplastic molded article, which comprises thermoforming the thermoplastic material according to claim 1 or 2. 7. A biodegradable thermoplastic molded article obtained by the method according to claim 6.