JPH0771824B2 - Novel laminated plate material and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a raw material for molding and processing using a natural raw material. Since this material has thermoplasticity in a water-containing state, it has the characteristic that it can be molded into various shapes while being humidified, and can be used as a new natural polymer-based molding material. Furthermore, this material has microbial degradability, and since the decomposed product is completely harmless to the environment,
As a novel biodegradable plastic with strong flexibility, it is used in various industrial fields that require molding.

[0002]

2. Description of the Related Art Natural materials generally have poor thermoplasticity, and as a result, they have been lacking in moldability as general-purpose plastics. Recently, however, the problem of waste of petroleum-based plastics has arisen, and the idea of preparing biodegradable plastics from natural materials has come up. In addition, there is an increasing demand to review the material as a special processing material by taking advantage of the texture of the natural material itself. for that purpose,
It is required to have physical properties such as having sufficient thermoplasticity during processing and being difficult to break. Even in natural polymers, starch and certain proteins have the property of having thermoplasticity and being capable of being molded when they contain water, but as a processing material, they are quite strong and difficult to break. It has only unsatisfactory physical properties. It is desirable that the material for processing has moderate transparency in addition to easiness of bending and bending, but natural materials for processing that satisfy these physical properties have not been developed.

As an artificial protein resin, there is a casein resin composed of milk protein, that is, casein. However, even if the physical properties of casein resin are improved, there are drawbacks such as low thermoplasticity in a water-containing state and weak bending strength. Processing was impossible. Even in an attempt to manufacture a plastic using gluten, satisfactory results such as transparency and strength have not been obtained. Further, although there is a report that the silk protein fibroin and the chitosan from the shells of the marine shells, which are the constituents of the present invention, have been studied as a film for a permeable membrane, a material having new properties containing these three components of glycerin There has been no attempt to produce a sheet-like material, and there has been no attempt to produce a plate-like material suitable for molding by further stacking these.

[0004]

The physical properties of the material required for the molding process are the appropriate transparency of the molded product, the thermoplasticity in the water-containing state, and the difficulty of breaking. Furthermore, it is more preferable if a decorative pattern can be put in the plate-shaped molded body. The present invention has been made for the purpose of providing a material for molding and processing which can satisfy such requirements based on a natural raw material and also a method for producing the same.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors cast and dry an aqueous solution in which fibroin, chitosan and glycerin coexist to prepare a sheet, Further, it was found that a material capable of being molded and having an appropriate transparency can be formed by humidifying and laminating this sheet and hot pressing, and based on this finding, the present invention has been completed.

That is, according to the present invention, by coexisting the above three components in an aqueous solution and casting and drying, the physical properties of the sheet that cannot be obtained by the single component or the two components can be exhibited. A transparent plate-shaped material that can be molded is obtained. If any of the above three components is lacking, it is difficult to exhibit the physical properties for molding.
Fibroin is indispensable as a transparent material capable of expressing water-containing thermoplasticity, and chitosan is necessary for imparting toughness to the material and appropriately compatibilizing with fibroin to homogenize the material and not impair transparency of the sheet. . Glycerin improves the film-forming property during sheet preparation, and evenly adsorbs moisture by humidification to facilitate the movement of molecular chains such as fibroin, thereby making it possible to perform laminated adhesion only by hot pressing. It is important that the three components exist in a uniform phase in the lamination of the sheets, and for that purpose, it is necessary to form the sheets by a casting and drying method of an aqueous solution in which the three components coexist.

[0007] The plate-shaped laminated sheet material obtained by laminating multiple sheets can exhibit the bending property essential for molding, that is, the property of extremely large bending toughness when heated with water because of its laminated structure. Further, the obtained laminated sheet is immersed in water or the like to remove an appropriate amount of glycerin, and hot-pressed again to finally obtain a plate-shaped material having hardness and water resistance suitable for molding. The details of the present invention are shown below, but the mixing ratio, temperature, water content, number of layers, etc. are not limited to this range.

The proportion of glycerin with respect to fibroin and chitosan is preferably 20 to 100%, and if it is out of this range, the film-forming property of the sheet deteriorates. The ratio of chitosan to fibroin is preferably 5 to 30%. If it is less than 5%, it becomes very brittle, and if it is more than 30%, the adhesiveness at the time of hot pressing deteriorates. An aqueous solution containing these three components is cast and dried to obtain a sheet. This sheet is moistened with steam or water to adjust the water content to preferably 10 to 70%, and preferably 5 or more sheets are laminated by hot press lamination at 50 to 200 ° C to form a laminated sheet having a thickness of several millimeters. obtain. In order to impart water resistance and the like, this laminated sheet is immersed in water or the like to remove glycerin, and the wet laminated sheet is hot-pressed again and dried to obtain a plate-shaped material for molding.

In order to improve the physical properties such as hardness of the plate-shaped material, it is possible to remove the glycerin by immersing it in an aqueous solution of ethanol or formalin instead of immersing it in water when removing glycerin. Further, in order to give coloring and other physical properties, a filler or a pigment,
A polymer or the like can also be added. It is also possible to obtain a plate-shaped material with a decoration inside by printing a pattern or the like on the sheet surface by an appropriate method and then laminating by hot pressing.

[0010]

Industrial Applicability By preparing the novel material of the present invention by the production method of the present invention, it is possible to provide a microbial-degradable plate-like material which is a molding material made of a natural polymer and which can be molded and processed. In recent years, development of microbial degradable plastics for molding has been required, and the present invention responds to this.

[0011]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1 A 5% aqueous solution of fibroin obtained by refining silk thread, a 1% aqueous chitosan solution in which chitosan was dissolved in 0.5% acetic acid aqueous solution, and reagent grade glycerin were prepared. These were mixed in a predetermined ratio and filtered through a 150-mesh filter cloth. Octyl alcohol, as an antifoaming agent, was poured onto these filtrates on the liquid surface, and defoaming was sufficiently performed under reduced pressure. These mixed liquids were cast on a stainless steel vat and blow-dried at 70 ° C. for 4 hours to obtain a sheet having a thickness of about 100 μm.

Each of these sheets was laminated 10 sheets, humidified to a water content of 40%, and heated at 150 ° C. for 1 minute to 300.
The laminated sheet was hopless at kg / cm ² . Further, this laminated sheet is immersed in water to deglycerin,
Again, 300 kg / cm ² hot pressing was performed at 110 ° C. for 5 minutes to obtain a plate-shaped material. Table 1 shows the comparison results regarding the properties such as plasticity of these various samples when heated with water.

[Table 1]

As is clear from this table, the laminated sheet can be molded only when fibroin, chitosan and glycerin coexist, and the necessary conditions as a molding material are satisfied.

Example 2 The effect of water content when hot pressing a sheet prepared under the same conditions as in Example 1 using fibroin: chitosan: glycerin in a ratio of 5: 1: 4 for 1 minute at 150 ° C. Table 2 shows the adhesive strength of the plate-shaped material.

[Table 2]

As is clear from the table, it is not suitable because the sheets are not bonded unless the sheets are hydrated and a laminated sheet is not formed, and it is necessary to hydrate the sheets. However, if the water content is too high, problems such as foaming occur, and the water content of the sheet was desired to be about 10 to 70%.

Example 3 A sheet prepared by using fibroin: chitosan: glycerin in a ratio of 5: 1: 4 under the same conditions as in Example 1 has a water content of 40% and a hot press temperature for 1 minute. The influence of is investigated in Table 3 by examining the adhesive strength of the plate-shaped material.

[Table 3]

As is apparent from the table, the press temperature is 50
If the temperature is lower than 0 ° C, sufficient adhesion is not achieved and the formation of the laminated sheet is insufficient. If the temperature is higher than 200 ° C., the evaporation of water is too strong and the formation of the laminated sheet is insufficient. Further, when the temperature was high as a whole, coloring tended to increase.
From this, it was found that the pressing temperature is preferably about 50 to 200 ° C.

Example 4 Using fibroin: chitosan: glycerin in a ratio of 5: 1: 4, prepared under the same conditions as in Example 1 and having a thickness of about 1
The water content of a sheet of 00 μm is 40% and it is 150 ℃ for 1 minute.
Table 4 shows the relationship between the bendability of a plate-shaped raw material piece having a length of 4 cm and hot-watered at 70 ° C. and the number of laminated sheets, which was prepared by hot pressing with. In addition, as a reference, the experimental results without stacking are also shown.

[Table 4]

If the sheets were not laminated, it was difficult to prepare a thick sheet, and this material lacked flexibility and was unsuitable for molding. It has been found that the plate-shaped material obtained by laminating has sufficient flexibility so that both ends of the plate-shaped material piece can be contacted without breaking in warm water when the number of layers is 5 or more.

A plate-shaped material obtained by preparing a laminated sheet of 10 layers at a water content of 40% at 150 ° C., deglycerin-treated and re-hot-pressing is water-resistant yellowish transparent. The physical properties suitable as a processing material such as hardness, flexibility when heated with water, and water absorption were obtained.

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Claims (2)

[Claims] 1. A plate-like material having thermoplasticity when containing water, which is obtained by laminating sheets composed of three components of fibroin, chitosan and glycerin. 2. The method for producing a plate-shaped raw material according to claim 1, further comprising the step of humidifying the sheets formed by the casting and drying method, and laminating and adhering the sheets by hot pressing.