JP2615440C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine silk fibroin powder from a silk substance. 2. Description of the Related Art It has use as an additive for goods and cosmetics. Conventionally, as a method of producing such fine powder of silk fibroin, a silk substance is dissolved in an aqueous solution containing a neutral salt, and then the neutral salt is removed to form an aqueous fibroin solution, and a precipitant is added to the aqueous solution. It is known to add silk fibroin to form a precipitate and then separate and dry the precipitate or freeze-dry the aqueous solution. However, such a method is still unsatisfactory industrially because the silk substance needs to be made into an aqueous solution once. On the other hand, when the silk material is directly pulverized, in this case, a part of the silk material changes its molecular structure and becomes non-crystallized, but most of the silk material has high strength but is deformed but fine. Unable to obtain powder. [0003] An object of the present invention is to provide a method for industrially advantageously producing a fine crystalline silk fibroin powder from a silk material. Means for Solving the Problems The present inventor has made intensive studies to solve the above problems, and as a result, has completed the present invention. That is, according to the present invention, after the silk material is brought into contact with an aqueous solution of sodium carbonate at a temperature of 95 ° C. or more to deteriorate the strength, the resulting silk material is subjected to dealkalization and drying, and then the obtained dried silk A method for producing a fine silk fibroin powder is provided, which comprises pulverizing a substance to an average particle size of 3 to 6 μm . According to the present invention, there is also provided a method for producing the above-mentioned fine powder of silk fibroin, wherein the fine powder of silk fibroin retains the crystal structure of the raw silk material. A method for producing the fine powder of silk fibroin described above, wherein the method is contained in a bag formed of a cloth material having voids. [0005] The silk material used in the present invention includes cocoon layer, cocoon thread, raw silk, silk fabric, and their waste. To preferably carry out the method of the invention, the silk material is firstly treated with an aqueous solution and an aqueous solution of sodium carbonate at a temperature above 95 ° C., preferably about 100 ° C.
Contact and process. The degree of alkalinity of the aqueous solution is pH 11.5 or more, preferably
Has a pH of 12 or more. Treatment of the silk material with an aqueous solution of sodium carbonate is performed by immersing the silk material in the aqueous solution. The time (treatment time) for bringing the silk substance into contact with the aqueous solution of sodium carbonate is as follows:
It is a time sufficient for the strength of the silk material to be degraded to a level suitable for pulverization regardless of the wild silk. For example, in the case of a silk thread, it may be brought into contact with an aqueous solution of sodium carbonate until its tensile strength becomes about 0.05 g / d or less. Generally, the processing time is
It is 1 to 4 hours, and when the fineness of raw silk is large, when sericin is fixed, or when it is hard to deteriorate like wild silk, additional time of 2 to 3 hours or more is required. The specific time required for contact with the aqueous solution of sodium carbonate can be easily determined by examining the relationship between the ease of pulverization of the silk material with reduced strength after alkali treatment and the contact time by a simple preliminary experiment. be able to. [0006] The silk material after the treatment with the aqueous solution of sodium carbonate is separated from the aqueous solution, and the sodium carbonate adhering thereto is removed by washing with water, dealkalized, and then dried. Next, the silk material thus obtained is comminuted. The fine pulverization of the silk material can be performed by a general pulverization method, but is preferably performed in a two-stage pulverization step of preliminarily pulverizing and then pulverizing. The coarse grinding is 15-
The pulverization is performed so that a pulverized product having an average size of about 30 μm is obtained.
This is performed so as to obtain a pulverized product having an average size of m . [0007] When the silk material is treated with an aqueous solution of sodium carbonate according to the present invention, the silk material is put into a bag formed in advance of a cloth having fine mesh-like voids, and the bag is washed with sodium carbonate . The treatment is preferably carried out by immersion in an aqueous solution. In such a treatment, the components dissolved from the silk substance in the aqueous solution of sodium carbonate and very small silk particles at the time of the treatment are passed through the fine voids of the cloth-like material forming the bag to form the bag. It can be easily removed to the outside. That is, after the treatment with the aqueous solution of sodium carbonate , the bag containing the silk substance can be passed through and easily removed to the outside of the bag. That is, after the treatment with the aqueous solution of sodium carbonate , the bag containing the silk substance can be passed through and easily removed to the outside of the bag. That is, carbonic acid
After aqueous workup sodium, immersing a bag body having the silk substance or shaken several times vertically or horizontally in an aqueous solution of sodium carbonate <br/>, the bag body in an aqueous solution of sodium carbonate <br/> By soaking or pulling, the solubilizing component of the silk substance and the fine silk substance can be removed to the outside of the bag through the fine voids of the cloth forming the bag. [0008] As the cloth-like material constituting the bag body, a woven or non-woven fabric formed of alkali-resistant fibers can be used. Examples of the alkali resistant fiber include a cotton fiber and a synthetic resin fiber. The size of the fine voids is appropriately selected according to the size of the silk material to be removed. Generally, however, only a fine silk material having a size of 1 μm or less can be selectively passed in an aqueous solution of sodium carbonate. Dimensions. [0009] When the silk substance is put into the bag and treated as described above, there is an advantage that the washing can be performed while the silk substance is kept in the bag when washing with water. Then, by performing the treatment with the aqueous solution of sodium carbonate and the dealkalization treatment after the treatment using the bag body, the treated silk substance can be collected with high efficiency. According to the present invention, fine silk fibron powder having an average particle diameter of 3 to 6 μm can be produced from a silk substance with a high yield. The fine powder of silk fibroin obtained by the present invention is crystalline, has properties equivalent to silk yarn, and has excellent hygroscopicity, moisture release and moisture permeability. Since the method of the present invention does not use a step of completely dissolving the silk material, the treatment operation is simple, and the amorphous portion of the silk material is removed when the aqueous solution of sodium carbonate is used. In addition, the resulting silk fibroin fine powder has excellent crystallinity, and has excellent performance as well as silk yarn. Therefore, the method of the present invention is excellent as an industrial production method of crystalline silk fibroin fine powder. Next, the present invention will be described in more detail by way of examples. Example 1 A raw silk of about 30 d (denier) was used as a sample, and 1 part by weight of the raw silk was immersed in an alkaline aqueous solution consisting of 1 part by weight of sodium carbonate and 30 parts by weight of water and boiled. In this treatment, as the treatment time elapses, the raw silk sample loses weight, the treatment for 40 minutes loses about 10%, and the treatment for 1 hour loses about 16%. In the above treatment, the tensile strength of the raw silk also deteriorated with the lapse of the treatment time, and after one hour of treatment, the tensile strength was reduced to about 0.04 g / d. In addition, the tensile strength in this case was measured using Tensilon and UTM-II type as an apparatus. Next, the raw silk treated as described above was washed with water and then dehydrated four times to remove alkali, and then dried at room temperature. Next, the dried raw silk was coarsely pulverized to an average particle size of about 20 μm and then finely pulverized. In this case, an ordinary pulverizer (sample mill, manufactured by Fuji Electric Co., Ltd.) was used for coarse pulverization, and a fine pulverizer (Current Jet, manufactured by Nisshin Engineering Co., Ltd.) was used for fine pulverization. The particle size of the finely pulverized raw silk (fine silk fibroin powder) thus obtained is 1
-20 μm, and the average particle size was about 5 μm. Next, when the fine powder was examined with a polarizing microscope, it was found that the fine powder was 4.0 × 10 to ^{3 to} 5.0 × 1.
It shows a birefringence of 0 to ³ and has a birefringence value of 5 for a generally known silk fibroin.
. The value was about the same as 2 × 10 to ³ . Therefore, it is considered that the orientation of the fibroin molecules in the fine powder as described above is the same as that of the silk fibroin. Further, the X-ray diffraction photograph of the fine powder confirmed this, and showed the same β-type as the silk thread. Further, from the result of heat measurement of the fine powder by a DSC device, no exothermic peak due to crystallization was observed in the DSC curve of this fine powder, and it was confirmed that the fine powder had the same crystallinity as silk fibroin. Furthermore, from the moisture absorption / desorption curve of the fine powder, it was confirmed that this powder showed only about 1% lower moisture content than the silk thread, and had the same absorption / desorption performance as the silk thread. . From the above, it was confirmed that the fine powder of silk fibroin obtained by the present invention had the same structure and function as silk thread. As described above, silk fibroin fine powder was obtained at a yield of about 70% by subjecting raw silk to alkaline treatment for about 1 hour. Example 2 An experiment was performed in the same manner as in Example 1 except that raw silk was put in a bag and subjected to an alkali treatment and a water washing treatment. In this case, as the bag, warp and weft: 50th, warp density: 25
Yarn / cm, weft yarn density: 20 yarns / cm, thickness: 0.25 mm, weight: 120 g / m
What used the cotton cloth of No. ² formed in the bag body was used. By using this bag, dissolved matter during the alkali treatment and ultrafine powder having a diameter of about 1 μm or less could be removed to the bag through the cotton cloth. In this example, silk fibroin fine powder could be obtained in a high yield of 70 to 60% by subjecting raw silk used as a raw material to an alkali treatment for about 2 to 3 hours. Example 3 An experiment was performed in the same manner as in Example 1 except that silk fabric was used instead of raw silk. In this case, too, silk fibroin fine powder could be obtained in a yield of 75% in an alkali treatment time of 1 hour.

Claims (1)

Claims 1. After the silk substance is brought into contact with an aqueous solution of sodium carbonate at a temperature of 95 ° C. or more to reduce the strength, the resulting silk substance is subjected to dealkalization and drying, and then obtained. A method for producing fine powder of silk fibroin, comprising pulverizing the dried silk material to an average particle size of 3 to 6 μm . 2. The process for producing fine silk fibroin powder according to claim 1, wherein the fine silk fibroin powder retains the crystal structure of the raw silk material. 3. The method for producing a fine powder of silk fibroin according to claim 1, wherein the silk substance is placed in a bag formed of a cloth having fine mesh-like voids in advance.