JP6494985B2 - Bioplastic manufacturing method and bioplastic molded body - Google Patents

Description

  The present invention relates to a method for producing bioplastic and a bioplastic molded body produced by the method.

  The polymer resin material is a material used in many products because of its advantages such as easy processing. In recent years, from the viewpoint of environmental protection, recyclable or biodegradable polymer resin materials using organic materials as a raw material, as represented by so-called bioplastics, have attracted attention.

  Patent Documents 1 and 2 relate to a method for producing a heat conductor and a derivative obtained by hot pressing a silk protein such as fibroin. By hot-pressing silk protein, a polymer resin material having biodegradability can be produced. Patent Document 1 aims to produce a material having excellent thermal conductivity among them, and Patent Document 2 aims to produce a material having excellent dielectric properties.

Japanese Patent No. 4783756 Japanese Patent No. 5084027

  A polymer resin material usually has a larger coefficient of thermal expansion than a metal or the like. In the field of semiconductor devices and precision equipment, thermal expansion of materials can have a significant impact on manufacturing quality and equipment functionality. For this reason, resin materials having a low coefficient of thermal expansion are required in many industrial fields such as processing equipment, semiconductor manufacturing equipment, optical equipment, measuring equipment, and electronic devices. On the other hand, there is a strong demand for using bioplastics in these devices in order to improve environmental adaptability.

  Then, the objective of this invention is providing the manufacturing method of the bioplastic with a comparatively small coefficient of thermal expansion, and the bioplastic molded object manufactured by the said method.

Manufacturing method according to the present invention is a method for producing a bio-plastics, and particle size adjustment step of the sheep wool mainly composed of keratin and ground to the fiber length is the fiber diameter equivalent 53μm into a powder, fiber A mixing step in which water is added to and mixed with the powder having a length corresponding to the fiber diameter, and a forming step in which hot-pressure forming is performed on the mixture of the powder and water. Moreover, the bioplastic molded body according to the present invention is molded based on the production method of the present invention.

  The method for producing a bioplastic according to the present invention uses a powder obtained by pulverizing hair containing keratin as a main component until the fiber length is equivalent to the fiber diameter, and is mixed with water to perform hot-pressure molding to obtain bioplastic It was.

  When the fiber length is relatively large, the constituents constituting the powder are fibrous. In such a case, since the fibrous structure remains in the microscopic structure in the bioplastic molded body, the direction of the assembly of the structure is generated, or a gap is generated between the structures. There is a risk that the molded body will not be homogeneous.

  On the other hand, in the present invention, the constituents of the powder become particles by pulverizing hair containing keratin as a main component until the fiber length is equivalent to the fiber diameter. For this reason, the bioplastic molded body tends to be homogeneous. This improves the physical properties of the bioplastic molded body and reduces the coefficient of thermal expansion.

In the present invention, in the mixing step, as a pretreatment of the hot pressing, the mixture is stored in a sealed container and heated to evaporate water in the sealed container to form the powder. You may mix. According to this, the evaporated water becomes easy to blend with the powder uniformly. Therefore, it can suppress that the bioplastic molded object becomes heterogeneous because water is unevenly distributed in the powder.

Contact name and "shall fiber length is less Xmyuemu" In the present invention, for example, when using a sieve, mesh opening sieve with sieve Xmyuemu, corresponding to those recovered as undersize fraction. Similarly, in the present invention, “the fiber length is X μm or more” corresponds to, for example, when a sieve is used, sieved using a sieve having an opening of X μm and collected as a sieve.

In the present invention, before Symbol granularity adjustment process, the fiber length was further pulverized the sheep wool may be as follows 32 [mu] m. Further, fibers having a fiber length of 32 μm or less may be separated. According to this, a homogeneous bioplastic molding was obtained by using wool powder having a fiber length equivalent to the fiber diameter as a raw material. As the bioplastic molded body became homogeneous, the coefficient of thermal expansion decreased and the bending strength also increased. Moreover, the bioplastic molded object which concerns on another viewpoint of this invention is a hot-pressure molded object of the wool powder which has a fiber length of 32-53 micrometers, Comprising: A thermal expansion coefficient is 29x10 < ^-6 > / K or less. A bioplastic molded product according to still another aspect of the present invention is a hot-pressed product of wool powder having a fiber length of 32 μm or less, and has a coefficient of thermal expansion of 17 × 10 ⁻⁶ / K or less.

FIG. 1 is a flow chart relating to a method for producing a bioplastic molded body. FIG. 2 (a) is an SEM photograph of wool before pulverization, and FIG. 2 (b) is an SEM photograph of wool powder after pulverization. FIG. 3 is a diagram of a pulse current sintering apparatus used in a molding process for performing hot-pressure molding. FIG. 4 is an SEM photograph of the bioplastic molded body.

  Below, the manufacturing method of the bioplastic which concerns on one Embodiment of this invention is demonstrated, referring FIG.

  First, in the particle size adjustment step S1, hairs that are raw materials are pulverized as follows. In this embodiment, hair whose main component is keratin is used. As the hair having keratin as a main component, wool, feathers, hair and the like are targeted. After washing raw wool such as wool, it is dried and cut. Thereafter, the cut hair is pulverized by a pulverization method such as a ball mill or a jet mill until a powder having a fiber length equivalent to the fiber diameter is produced. Freeze grinding may be used when grinding the hair. Moreover, you may grind | pulverize the hair after cooking. Freezing and steaming are done to make the hair brittle and easy to grind. The fiber diameter equivalent includes a size from the fiber diameter to about 1.5 times the fiber diameter. For example, when the hair is wool, the hair is pulverized until a powder having a fiber length of 53 μm or less is produced. Preferably, the hair is pulverized until a powder having a fiber length of 32 μm or less is produced. For example, when pulverizing with a ball mill, the size of the ball, the material of the ball, the pulverizing time, the number of rotations, the standing time (the time for temporarily stopping the pulverization and cooling), etc. are preferably adjusted appropriately depending on the object to be pulverized. . The pulverization may be performed in a plurality of times. For example, after pulverization, the powder remaining on the sieve may be pulverized again. FIG. 2 (a) is a SEM (Scanning Electron Microscope) photograph of the wool before pulverization, and FIG. 2 (b) is an SEM photograph of the wool powder after pulverization.

  After grinding, the hair powder is sieved. As the sieve, one having an aperture of 53 μm or an aperture of 32 μm is used. Thereby, the powder whose fiber length is 53 micrometers or less, or the powder whose fiber length is 32 micrometers or less can be obtained. Moreover, you may use combining said sieve. For example, when a 53 μm sieve is used and then a 32 μm sieve is used for the powder that has passed through the sieve, a powder having a fiber length of 32 to 53 μm can be obtained. It is important to consider the optimization of the pulverization conditions. For example, it is appropriately sieved so as not to overgrind, and only the sieve is further crushed. Thereby, it can suppress that cost becomes excessive. A sieve having a mesh size of less than 32 μm may be used. In this case, a powder in which the upper limit and the lower limit of the fiber length are adjusted to less than 32 μm can be obtained. As described above, the particle size may be adjusted with a sieve, or the particle size may be adjusted without using a sieve. For example, the hair may be pulverized until the desired particle size is obtained, and the pulverized hair may be used as it is in the next step without being sieved.

  Next, in the mixing step S2, water and the hair powder obtained in the step S1 are mixed. First, the hair powder and 10 to 40% by mass of water with respect to 100% by mass of the mixture are put in a mortar or the like and mixed. Thereafter, a mixture of water and hair powder is put into a container and heated, and kept at a temperature higher than normal temperature for a certain period of time. This evaporates the water in the container and allows the hair powder to conform to the water. It is desirable that the amount of water added, temperature, and time are appropriately adjusted. In addition, it is preferable to use a container that can be sealed, and after heating water and powder, the container is heated in a sealed state. As described above, when water and hair powder are blended, water is uniformly distributed in the hair powder. If the water in the hair powder is uneven, the finally obtained bioplastic molded product may not be homogeneous. In contrast, as described above, water is evaporated in a sealed container and blended into a powder, so that the finally obtained bioplastic molded body tends to be homogeneous.

  Next, in the molding step S3, a bioplastic molded body is produced from the mixture obtained in the step S2. For example, a pulse current sintering apparatus 1 as shown in FIG. 3 is used. The pulse current sintering apparatus 1 includes electrodes 10 and 20, a power source 30, a vacuum chamber 40, and a cylindrical die 50. A graphite punch 12 protruding downward in the vacuum chamber 40 is fixed to the lower end of the electrode 10. The punch 12 is inserted into the die 50 from above. A graphite punch 22 protruding upward in the vacuum chamber 40 is fixed to the upper end of the electrode 20. The punch 22 is inserted into the die 50 from below. In the die 50, in the space between the punches 12 and 22, the mixture obtained in the step S2 is arranged. The electrodes 10 and 20 are connected to a power source 30.

  The pulse current sintering apparatus 1 having the above configuration is used as follows, and the mixture is subjected to hot pressing. The inside of the vacuum chamber 40 is depressurized to 6.0 Pa or less. By loading the electrode 10 from above, the mixture is pressurized at a pressure of 20 to 40 MPa. Then, by operating the power supply 30 while pressurizing the mixture, a large pulsed current is passed through the mixture via the electrodes 10 and 20 and the punches 12 and 22, and heat generation due to Joule heat is generated in the mixture. Thus, the mixture is heated at a rate of 5 to 50 ° C./min, heated to 75 to 150 ° C., and then naturally cooled to obtain a bioplastic molded body. In addition, you may perform hot-pressure shaping | molding with a hot press, a heat drawing machine, etc. instead of the pulse electric current sintering apparatus 1. FIG.

  Next, in the drying step S4, the bioplastic molded body obtained in the step S3 is dried. For example, it is preferable to dry for 21 days or more while keeping the temperature at about 100 ° C. It is desirable that the drying temperature and the drying time are appropriately adjusted according to the dry state.

  According to the bioplastic manufacturing method of the present embodiment described above, a bioplastic molded body is formed from a hair powder whose main component is keratin, the fiber length of which corresponds to the fiber diameter. When the fiber length of the constituent constituting the powder is relatively large, the fibrous constituent remains in the microscopic structure in the bioplastic molded body. For this reason, there exists a possibility that a molded object may not become uniform because directionality arises in the aggregate | assembly of a structure or a space | gap arises between structures. On the other hand, in this embodiment, since the bioplastic is molded from powder whose fiber length is equivalent to the fiber diameter, the molded body tends to be homogeneous. As a result, physical properties such as a low coefficient of thermal expansion or an increased bending strength are improved.

[Example 1]
Examples according to the present invention will be described below in detail together with comparative examples. After washing and drying, the raw wool from which dirt has been removed is cut into a length of about 10 mm. Grinding the cut wool with a planetary ball mill (FRITSCH, P-6) using 15 mm and 20 mm alumina balls at a rotation speed of 300 rpm for 1 minute, and then leaving it for 5 minutes Was repeated (S1). The pulverized wool powder is passed through sieves having openings of 32 μm, 53 μm, 74 μm, 105 μm and 250 μm, and fiber lengths of 105 to 250 μm, 74 to 105 μm, 53 to 74 μm, and 32 to 53 μm And were separated into those of 32 μm or less (S1).

  Next, wool powder of each fiber length and 20% by mass of water with respect to 100% by mass of the mixture were put in a mortar and mixed. Thereafter, the mixture of water and wool powder of each fiber length was put in a sealable plastic bag, sealed, and kept at 60 ° C. for 24 hours in an electric furnace (manufactured by ASONE, VACUUM OVEN AVO-250N) (S2).

  Next, the mixture of water and wool powder was sintered using the pulse current sintering apparatus 1 (S3) and then dried to obtain a bioplastic molded body (S4). The vacuum degree of the vacuum chamber 40 was 6.0 MPa, the pressurizing pressure was 20 MPa, the heating rate was 20 ° C./min, and the sintering temperature was 150 ° C. Drying was performed by keeping the temperature at about 100 ° C. for 21 days in an electric furnace (manufactured by ASONE, VACUUM OVEN AVO-250N). As a result, a disk-shaped bioplastic molded body having a thickness of 4 mm and a diameter of 15 mm was obtained.

  FIG. 4 shows SEM photographs of “cross section” and “vertical surface” of a bioplastic molded body prepared from wool powder adjusted to each fiber length. The “vertical plane” photograph shows a photograph of a plane along a direction perpendicular to the cross-sectional direction of the “cross-section” photograph. When the cross-sectional photographs of 300 times and 1000 times of the bioplastic molded body having fiber lengths of 105 to 250 μm, 74 to 105 μm, and 53 to 74 μm were seen, the cross section of the fiber appeared. Similarly, when the vertical plane photographs of 300 times and 1000 times of bioplastic molded bodies having fiber lengths of 105 to 250 μm, 74 to 105 μm, and 53 to 74 μm were seen, long fiber shapes appeared. That is, there was a fiber that was not completely melted in a bioplastic molded body produced from wool powder having a fiber length of 105 to 250 μm, 74 to 105 μm, and 53 to 74 μm. As a result, non-homogeneous bioplastics may be formed due to the direction in the molded body caused by fibers that have not been completely melted or voids between the areas of the fibers that have not been completely melted and the melted areas. It was a molded body.

  On the other hand, the cross section of the fiber and the shape of the long fiber did not appear in the SEM photograph having a fiber length of 32 to 53 μm and 32 μm or less, and a homogeneous bioplastic molded body was obtained. As can be seen from the SEM photograph of the wool fiber in FIG. 2, the diameter of the wool fiber is about 30 μm. That is, a homogeneous bioplastic molded body was obtained from wool powder having a fiber length equivalent to the fiber diameter (including a size from the fiber diameter to about 1.5 times the fiber diameter).

[Example 2]
A disc-shaped bioplastic molded body having a thickness of 4 mm and a diameter of 15 mm was produced from wool having a fiber length of 105 to 250 μm, 74 to 105 μm, 53 to 74 μm, 32 to 53 μm, and 32 μm or less in the same manner as in Example 1. . The thermal expansion coefficient of the bioplastic molded body of each fiber length was measured using a thermal expansion measuring device (manufactured by SII, TMA / SS6300).

When the fiber length is in the range of 74 μm or more, the coefficient of thermal expansion is as large as about 40 × 10 ⁻⁶ / K. On the other hand, 34 × 10 ⁻⁶ / K at 53 to 74 μm, 29 × 10 ⁻⁶ / K at 32 to 53 μm, 17 × 10 ⁻⁶ / K at 32 μm or less, and before and after the fiber length becomes 53 μm, As the fiber length becomes shorter, the value of the coefficient of thermal expansion of the bioplastic molded body becomes smaller. That is, the coefficient of thermal expansion decreases from the point when the fiber length is equivalent to the fiber diameter. Therefore, it was found that the physical characteristics are improved by the homogeneity of the bioplastic.

[Example 3]
A disc-shaped bioplastic molded body having a thickness of 4 mm and a diameter of 15 mm was prepared from wool powder having a fiber length of 74 to 105 μm and a length of 32 μm or less in the same manner as in Example 1. The maximum bending stress of the bioplastic molded body of each fiber length was measured by a three-point bending strength test using a bending tester (manufactured by Shimadzu Corporation, AGS-X 10N-10kN).

  The maximum bending stress of the bioplastic molded body produced from wool having a fiber length of 32 μm or less was 103 MPa. On the other hand, the bending stress of the bioplastic molded body having a fiber length of 74 to 105 μm was 74 MPa. From this experimental result, it was also found that a material having excellent physical properties such as maximum bending stress can be obtained from the wool powder having a fiber length that becomes a homogeneous bioplastic molding.

1 Pulse Current Sintering Apparatus 10, 20 Electrode 12, 22 Punch 30 Power Supply 40 Vacuum Chamber 50 Die

Claims (5)

And particle size adjustment step of the powder that fiber length sheep wool mainly composed of keratin and ground to a fiber diameter equivalent 53 .mu.m,
A mixing step in which water is added to and mixed with the powder containing fiber length equivalent to the fiber diameter;
A method for producing a bioplastic comprising a molding step of subjecting the powder and water mixture to hot-pressure molding. In the mixing step, as a pretreatment of the hot pressing, the mixture is accommodated in a sealed container and heated to evaporate water in the sealed container and mix with the powder. The manufacturing method according to claim 1. Prior Symbol granularity adjustment process method according to claim 1 or 2 fiber length was further pulverized the sheep hair, characterized in that with: 32 [mu] m. A hot-pressed body of wool powder having a fiber length of 32 to 53 μm, having a thermal expansion coefficient of 29 × 10 ^-6 / K or less bioplastic molded body, A hot-pressed body of wool powder having a fiber length of 32 μm or less, having a thermal expansion coefficient of 17 × 10 ^-6 / K or less bioplastic molded body,