JP3960141B2 - Purification method of sericin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for purifying sericin, which is obtained by drying a sericin aqueous solution obtained in a spinning process or a scouring process, or a sericin aqueous solution in which sericin is eluted in water for extraction of sericin from cocoons and silk threads. In particular, the present invention relates to a purification method for classifying and purifying sericin having different molecular weights.
[0002]
[Prior art]
  Sericin is useful as a raw material for cosmetics and pharmaceuticals. Conventionally, a sericin aqueous solution obtained as a waste liquid in the spinning process and scouring process, or a sericin aqueous solution in which sericin is eluted in water for extraction of sericin from silkworms and silk thread, has been used. The sericin powder is obtained by drying.
[0003]
  As this drying method, application of techniques such as spray drying, freeze drying, reduced pressure drying and the like used particularly in the field of the food industry has been attempted. For example, JP-A-4-202435 discloses scouring containing sericin. A method is disclosed in which a waste solution is ultrafiltered to obtain a concentrated solution of sericin, and the concentrated solution is spray-dried. Japanese Patent Application Laid-Open No. 10-140154 discloses that a sericin powder is obtained by mixing a water-soluble organic solvent such as methanol, ethanol, dioxane or the like into a sericin aqueous solution to precipitate sericin, followed by filtration and drying. Is described. Japanese Patent Application Laid-Open No. 2000-184868 discloses that sericin hydrolyzate is eluted by treating soot with sodium carbonate water at 80 ° C. for 1 hour, the eluate is concentrated under reduced pressure, and the condensate is removed by filtration. It is disclosed that a double amount of ethanol is added to precipitate a sericin hydrolyzate, which is filtered and freeze-dried to obtain a sericin hydrolyzate powder.
[0004]
  These methods use scouring waste liquid or hydrolyze the scouring waste liquid with alkali and are effective for obtaining sericin having a small molecular weight, but having a large molecular weight of about 500,000. It is unsuitable for In addition, sericin is not purified by classification into different molecular weights. For example, sericin having a large molecular weight of about 500,000 or more and a sericin having a molecular weight of about 150,000 or less are used. It does not meet the requirements for classification and purification as the main component.
[0005]
[Problems to be solved by the invention]
  In view of these problems, the present invention seeks to provide an efficient method for purifying sericin from a mixture of sericin and water into several molecular weight grades including a molecular weight grade as large as about 500,000. To do.
[0006]
[Means for Solving the Problems]
  The gist of the present invention includes sericin having a molecular weight of 500,000 or more.Lower pipe waste liquidStep 1 for preparing
TheLower pipe waste liquidThe air permeability is 1-7cm³/(cm²・ S)And filtering with a filter cloth that is
Is a method for purifying sericin.
[0007]
  The step 2 may include a step of enclosing the mixture in a bag including the filter cloth and pressurizing the bag in which the mixture is encapsulated.
[0008]
  The method for purifying sericin is as follows:
Mixing the first filtration residue obtained in step 2 with a water-soluble organic solvent; and
Filtering the first filtration residue mixed with the water-soluble organic solvent through a second filter cloth;
Drying the second filtration residue obtained in step 4; and
Can be included.
[0009]
  The water-soluble organic solvent can be ethanol.
[0010]
  The step 5 may include a hot air drying step.
[0011]
  The step 4 encloses the first filtration residue in a second bag including the second filter cloth, and pressurizes the second bag in which the first filtration residue is enclosed. Steps may be included.
[0012]
  The method for purifying sericin may include a step 6 of ultrafiltration of the filtrate filtered in the step 2.
[0013]
  The method for purifying sericin may include a step 8 of drying the retentate generated in the step 6.
[0014]
  The method for purifying sericin may include step 7 of adding hydrogen peroxide to the retentate produced in step 6 to gel the sericin in the retentate and then filtering the retentate.
[0015]
  The filtration in the step 7 may include a step of filtering with a third filter cloth, and the air permeability of the third filter cloth is 1 to 7 cm.³/(cm²・ S)It can be.
[0016]
  The method for purifying sericin may include a step 9 of ultrafiltration of the filtrate produced in the step 6 and / or the filtrate produced in the step 7.
[0017]
  The method for purifying sericin may include a step 10 of drying the retentate generated in the step 9.
[0018]
  Step 10 includes
A vacuum concentration step of vacuum concentration of the retentate produced in step 9;
A reduced-pressure drying step of drying the concentrated solution produced in the reduced-pressure concentration step under reduced pressure;
Can include.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
  FIG. 1 is a process diagram showing the flow of steps of the method for purifying sericin according to the present invention. The aspect which concerns on this invention is demonstrated in detail following a process below.
[0020]
  Step 1: A mixture of sericin and water is prepared. As sericin, one having a large average molecular weight is used. In this respect, as the mixture of sericin and water, the lower pipe waste liquid is preferable for the reason described later. The lower pipe waste liquid is a mixture of sericin and water recovered in the lower pipe process. The lower pipe process is a rewinding process in which the silk thread used for the weft of the silk fabric is wound in a wet state, and the sericin adhering to the silk thread is watered by the squeezing or pressing force applied to the thread that is running or wound. At the same time, it is separated into waste liquid and recovered as lower pipe waste liquid. In the present specification, the average molecular weight means a weight average molecular weight unless otherwise specified.
[0021]
  The lower pipe waste liquid usually contains about 1% by weight of sericin. In addition, sericin contained in the lower pipe waste liquid is not affected by chemicals different from sericin obtained in the scouring process, so it has a high molecular weight, so it does not completely dissolve in water and exists in the lower pipe waste liquid in a gel state. To do.
[0022]
  Step 2: First, a mixture of sericin and water is filtered using a filter cloth. The filter cloth has an air permeability of 1-7cm³/(cm²・ S)A woven filter cloth (measured at a pressure of 125 Pa by a Frazier type tester according to JIS L 1096 8.27.1 A method) is preferably used. In a mixture of sericin and water having a large average molecular weight, sericin molecules are associated with each other in the liquid and partially gelled. By this filtration, sericin having a relatively low molecular weight passes through the filter cloth as an aqueous solution and becomes a filtrate. Since sericin having a large molecular weight is gelled, it does not pass through the filter cloth and remains on the liquid supply side of the filter cloth as the first filtration residue. The first filtration residue remains as a tofu-like soft object.
[0023]
  In step 2, it is preferable to form a filter cloth into a bag shape, seal the bag with a mixture of sericin and water, pressurize the sealed bag, and squeeze out the liquid material. For example, a bag containing 50 liters of the mixture is pressed between the upper and lower sides with a pressure plate. The pressurizing force is gradually increased, and after reaching 500 to 1000 N, pressurization is continued. Pressurization is continued for about 1 day. An air cylinder is preferably used as the pressurizing means. As the pressurizing means, a method may be used in which a bag-like filter cloth containing a mixture is twisted to squeeze out the moisture therein. As the filtering means, a filter such as a filter press may be used.
[0024]
  The first filtration residue obtained in the step 2 is a mixture of sericin mainly composed of sericin having a molecular weight of about 500,000 or more and water. It can also be offered to the market as 1).
[0025]
  Step 3: Next, an approximately equivalent amount (weight ratio) of a water-soluble organic solvent is added to the first filtration residue obtained in Step 2, and the mixture is mixed using a stirring means such as a mixer. Examples of the water-soluble organic solvent include acetone and alcohol, but ethanol is most preferable because it does not cause adverse effects on the environment and the living body. The water-soluble organic solvent has an effect of stopping the drying rate in Step 5-1 described later.
[0026]
  Step 4: The first filtration residue mixed with the water-soluble organic solvent is filtered using a filter cloth. The filter cloth has an air permeability of 1-7cm³/(cm²・ S)The woven filter cloth is preferably used. By this filtration, a second filtration residue in the form of okara is obtained.
[0027]
  Step 5-1: Okara-like second filtration residue obtained in Step 4 is heat-dried in the air. Heat drying is preferably performed at 40 to 55 ° C. It is more preferable to carry out at 45-50 degreeC at the point which stops a drying rate and does not denature sericin. Heat drying is more preferably hot air drying in terms of stopping the drying speed. By this drying, the moisture of the second filtration residue is reduced to a solid.
[0028]
  Step 5-2: The solid material obtained in Step 5-1 is pulverized into particles and dried under reduced pressure. As a result, a sericin powder (dried sericin 1) containing sericin having a molecular weight of about 500,000 or more as a main component is obtained.
[0029]
  Step 6: The filtrate roughly filtered in Step 2 is ultrafiltered and concentrated using an ultrafiltration apparatus having a molecular weight cut off of 150,000. Depending on the application, the molecular weight cut off can be varied. In addition, since linear polymers such as sericin are entangled in a string in the liquid, the molecular weight cut off of sericin is higher than the standard molecular weight cut off.
[0030]
  Step 7: Hydrogen peroxide is added to the concentrated solution concentrated in Step 6 so as to have a concentration of 0.5% by weight, and sericin contained in the concentrated solution is gelled. The concentrated solution containing gelled sericin is filtered to take out the residual gel. A filter cloth is used for filtration. The air permeability of the filter cloth is 1-7cm³/(cm²・ S)It is.
[0031]
  The gel obtained in the step 7 is a mixture of sericin mainly composed of sericin having a molecular weight of approximately 100,000 to 200,000 and water, and is used as it is or by adding water as a medium molecular weight sericin-containing liquid (liquid 2). It can also be offered to the market.
[0032]
  Step 8: The gel obtained in Step 7 is dried under reduced pressure. Thereby, the dried sericin (dried sericin 2) which has a molecular weight of about 100,000 to 200,000 as a main component is obtained.
[0033]
  This vacuum drying in step 8 is preferably performed in two stages of vacuum concentration and vacuum drying because the drying efficiency is increased. For example, this is performed using the apparatus shown in FIGS. The vacuum concentrator 6 for vacuum concentration that can be suitably used in the present invention shown in the plan view of FIG. 2A and the longitudinal sectional view of FIG. 2B includes a vacuum concentration container 12 and a vacuum concentration container. And a vacuum concentration container heating means 30 for heating 12. The vacuum concentration container heating means 30 includes a hot water tank 46, hot water 48 stretched on the hot water tank 46, and an electric heater 47. A lid 32 is attached to the vacuum concentration container 12. The lid 32 is fastened to the opening edge 36 of the vacuum concentration container 12 by a bolt 34. In the lid 32, a suction pipe 36 that is electrically connected to the inside of the reduced pressure concentration container 12 is erected from the center portion toward the outside. A pressure gauge 31 that displays the pressure inside the vacuum concentration container 12 is connected to the tip of the suction pipe 36. A pipe 38 branches off from the middle part of the suction pipe 36, and one end 27 of the coupler is connected to the tip of the pipe 38. Further, a connecting pipe 39 branches from an intermediate portion of the pipe 38. The connecting pipe 39 is used to pre-depressurize the decompression and concentration vessel 12 in advance by an auxiliary vacuum pump (not shown), and has a coupler one side 40 at the tip and a valve 42 in the middle. If the preliminary decompression is not performed, the connecting pipe 39 is not necessary.
[0034]
  The gel 9 which is the above residue is put into the state shown in FIG. A screen 44 is attached to the lid 32 so as to cover the opening of the suction pipe 36 so that liquid droplets scattered when the liquid of the content of the vacuum concentration container 12 boils do not enter the suction pipe 36. It has been.
[0035]
  The vacuum concentration container 12 is housed in a hot water tank 46. Hot water 48 heated by an electric heater 47 is stretched in the hot water tank 46. The vacuum concentration container 12 is immersed in the warm water 48 with the upper edge remaining in a state where the warm water 48 is not put therein, and the wall surface of the vacuum concentration container 12 is heated using the warm water 48 as a medium. By keeping the temperature of the hot water 48 constant, the temperature of the wall surface 51 of the vacuum concentration container 12 is kept constant. By circulating the hot water 48 in the tank by a circulation means (not shown), the temperature of the wall surface 51 of the vacuum concentration container 12 is kept uniform regardless of the location. The vacuum concentration container 12 is placed on the grid-like gantry 52 so that the outer bottom is in contact with the hot water 48.
[0036]
  The vacuum concentration by the vacuum concentrator 6 is preferably performed at a temperature of 42 ° C. or lower and 13 ° C. or higher under a reduced pressure of 1333 to 3333 Pa using a vacuum pump or the like through a pipe 38. It is preferable to concentrate under reduced pressure at about 28-40 ° C. By this treatment, the gel 9 is concentrated and becomes a syrup-like high-viscosity soft body. The time required to reach such a state varies depending on conditions such as the amount of the input liquid, the temperature of the liquid under reduced pressure, the pressure of the reduced pressure, etc. For example, 4 liters of liquid maintained at 40 ° C. The time until it becomes a soft body is about 6 hours.
[0037]
  From the high-viscosity soft body, water vapor generated inside the soft body due to boiling is difficult to escape to the outside, and since the high-viscosity soft body is unlikely to generate convection, heat is not easily transmitted from the wall surface of the vacuum concentration vessel 12 and is concentrated. Progresses slowly.
[0038]
  In order to further advance the concentration and dry, the soft body is then placed in a vacuum drying container 14 that can be suitably used in the present invention, as shown in the plan view of FIG. 3A and the longitudinal sectional view of FIG. It is transferred to. The transfer is performed by closing the valve 22 and then putting the soft material in the vacuum concentration container 12 into the vacuum drying container 14 by moving means such as scooping with a spatula (not shown). The reduced pressure concentration container 12 is detachably attached to the hot water tank 46. Further, the vacuum drying container 14 has an inner bottom surface 90 as wide as possible within a range where there is no problem in strength. The soft material is preferably deposited in a layered manner on the bottom of the vacuum drying container 14 with a thickness of 1 to 50 mm, more preferably 10 to 30 mm. If the layer is too thin, the drying time will be faster, but the throughput will be less and the efficiency will be poor. If the layer is too thick, it will be difficult to dry.
[0039]
  The reduced-pressure dryer 10 for reducing the reduced-pressure drying includes a reduced-pressure drying container 14 and a reduced-pressure drying container heating means 50 for heating the reduced-pressure drying container 14. The vacuum drying container heating means 50 includes a hot water tank 76, hot water 78 stretched on the hot water tank 76, and an electric heater 75. The vacuum drying container 14 has a shallow box shape with a flat inner bottom surface 90. A lid 52 is attached to the vacuum drying container 14. The lid 52 is fastened to the opening edge 56 of the vacuum drying container 14 by the bolt 34. In the lid 52, a suction pipe 56 that constitutes the flow path 20 that is electrically connected to the inside of the vacuum drying container 14 is erected from the center portion toward the outside. A pressure gauge 31 that displays the pressure inside the vacuum drying container 14 is connected to the tip of the suction pipe 56. A pipe 58 branches off from an intermediate portion of the suction pipe 56, and one end portion 67 of the coupler is connected to the tip of the pipe 58. Further, a connecting pipe 59 branches from an intermediate portion of the pipe 58. The connection pipe 59 is used to depressurize the vacuum drying container 14 in advance by an auxiliary vacuum pump (not shown), and has a coupler one end 68 at the tip and a valve 72 in the middle. If the preliminary decompression is not performed, the connecting pipe 59 is not necessary.
[0040]
  A screen 57 is attached to the lid 52 so as to prevent the liquid droplets scattered when the liquid in the vacuum drying container 14 boils from entering the suction pipe 56 so as to cover the opening of the suction pipe 56. It has been.
[0041]
  The vacuum drying container 14 is stored in a hot water tank 76. Hot water 78 heated by an electric heater 75 is stretched in the hot water tank 76. The vacuum drying container 14 is immersed in the warm water 78 with the upper edge remaining in a state where the warm water 78 is not put therein, and the wall surface 80 of the vacuum drying container 14 is heated using the warm water 78 as a medium. By keeping the temperature of the hot water 78 constant, the temperature of the wall surface 80 of the vacuum drying container 14 is kept constant. By circulating the hot water 78 in the tank by a circulation means (not shown), the temperature of the wall surface 80 of the vacuum drying container 14 is kept uniform regardless of the place. The vacuum drying container 14 is placed on the grid-like gantry 77 so that the outer bottom is in contact with the hot water 78.
[0042]
  A box body 84 is attached to the lid 52 so that the upper surface 81 of the lid 52 is covered with the opening portion down. An infrared heater 88 is attached to the inner upper surface 86 of the box 84 so as to heat the upper surface 81 of the lid 52. The lower surface 85 of the lid 52 is heated by the infrared heater 88 through the upper surface 81, and the space 87 inside the vacuum drying container 14 is heated with the lid 52 being covered. The vacuum drying container 14 has a flat and substantially horizontal inner bottom surface 90, and the inner space 87 in a state where the lid 52 is closed has a flat shape, and the lower surface 85 of the lid 52 and the inner bottom surface 90 of the vacuum drying container 14 The interval of is narrow. As a result, the soft body 8 charged in the vacuum drying container 14 and staying in a layered form is efficiently heated from above.
[0043]
  The soft body 8 is dried under reduced pressure at a temperature of 42 ° C. or lower under reduced pressure of 1333 to 3333 Pa using a decompression means such as a vacuum pump through a pipe 58.
[0044]
  In the vacuum concentrator 6 and the vacuum dryer 10, heating means using warm water as a medium is preferable as the heating means for heating the gel-like or soft body. Those that heat directly or indirectly using an induction heating device, those that heat the vacuum concentration container 12 and the vacuum drying container 14 with a mantle heater, those that heat the vacuum concentration container 12 and the vacuum drying container 14 with infrared rays, etc. Also good.
[0045]
  The soft body is dried while generating a large number of bubbles by the reduced-pressure drying apparatus 10, and becomes a porous solid in a state where the drying proceeds to a predetermined degree. The time until the soft body is dried varies depending on the drying conditions, but it takes about 24 hours for the soft body having a thickness of 2 cm kept at 40 ° C. to dry.
[0046]
  This porous solid is pulverized to obtain sericin powder. Since the solid is porous, the pulverization for powdering can be performed very easily and efficiently.
[0047]
  In Step 8, if the efficiency is not questioned, the gel-like material may be directly put into the vacuum drying apparatus 10 without using the vacuum concentration apparatus 6, and drying may be performed.
[0048]
  In such a method for drying sericin according to the present invention, concentration and drying are performed under reduced pressure of 1333 to 3333 Pa. Therefore, the boiling point of water does not exceed 40 ° C., and the temperature of sericin is increased during concentration and drying. It does not rise above 42 ° C, which is the heat denaturation temperature of sericin. Therefore, sericin is not denatured by heat by drying.
[0049]
  Such a method for drying sericin does not require a large and expensive apparatus such as freeze-drying. Further, a large amount of energy cost for freezing a large amount of water as a solvent is not required.
[0050]
  Step 9: The filtrate obtained by filtering the filtrate filtered in Step 6 and / or the gelled sericin contained in the concentrate in Step 7 is further reduced to a molecular weight limit of 10,000. Ultrafilter using a filtration device and concentrate. Depending on the application, the molecular weight cut off can be varied.
[0051]
  The concentrated solution obtained in Step 9 is a mixture of sericin mainly composed of sericin having a molecular weight of about 30,000 to 70,000 and water, and as it is or by adding water, a high molecular weight sericin-containing liquid (liquid 3) is obtained. It can also be offered to the market.
[0052]
  Step 10: The concentrated liquid obtained in Step 9 is dried under reduced pressure. As a result, a sericin powder containing sericin having a molecular weight of about 3 to 70,000 as a main component is obtained. The drying under reduced pressure is preferably carried out in two stages using the apparatus shown in FIGS. 2 and 3 in the same manner as in step 7, since the drying efficiency is increased.
[0053]
  Through the above steps, a sericin powder mainly composed of sericin having a molecular weight of about 500,000 or more (step 6), and a sericin powder mainly composed of sericin having a molecular weight of about 100 to 200,000 (step 7), A sericin powder (step 9) containing sericin having a molecular weight of about 3 to 70,000 as a main component is obtained.
[0054]
  Of course, it is generally possible to fractionate a substance into substances with different molecular weights by changing the molecular weight of ultrafiltration and performing multiple fractionation. It is difficult to use ultrafiltration to separate sericin having a molecular weight of about 500,000 or more. This is because it is difficult to make a mixed solution of sericin and water containing such a large molecular weight, and gelled sericin exists in the solution. The filtration process is not smoothly performed by pinching the filtration membrane.
[0055]
  Even in an aqueous solution containing sericin having a molecular weight of 500,000 or less, the sericin molecule is entangled in water in a string shape, so that it can be fractionated into sericin having a sharp molecular weight distribution by simply performing ultrafiltration. Is difficult.
[0056]
  In the present invention, sericin powders or sericin-containing liquids having different molecular weights can be obtained by combining ultrafiltration and filtration with a filter cloth and performing filtration under the above-mentioned predetermined conditions. .
[0057]
  As the mixture of sericin and water prepared in step 1, one having a large average molecular weight and containing sericin is used. In this respect, the lower pipe waste liquid is preferable as the mixture of sericin and water.
[0058]
  Example
  Step 1: 51 liters of lower pipe waste liquid (concentration: 1.1% by weight) were prepared.
[0059]
  Step 2: The lower pipe waste liquid was sealed in a bag made of filter cloth. The filter cloth has an air permeability of 6cm³/(cm²・ S)A woven filter cloth was used. The filter cloth bag containing the lower pipe waste liquid was pressurized with a press using an air cylinder. The applied pressure was 600 N. The applied pressure was increased to 600 N over 4 hours from the start of pressurization, and then the applied pressure was maintained for 20 hours.
[0060]
  The (first) filtration residue of this filtration is 4000 cm of a mixture of sericin and water with a sericin content of 6%.³Obtained. In addition, 47 liters of a liquid mixture of sericin and water having a sericin content of 0.6% was obtained as the filtrate that passed through the filter cloth.
[0061]
  Step 3: Tofu-like mixture of sericin and water obtained in Step 2 4000 cm³And ethanol 3800cm³And stirred with a mixer.
[0062]
  Step 4: This stirred product was filtered under the same pressure conditions as in Step 2 using the same filter cloth bag as in Step 2. As a (second) filtration residue of this filtration, 1982 g of a mixture of sericin, water and ethanol having a sericin content of 11.7% was obtained.
[0063]
  Step 5-1: 1982 g of okara-like mixture of sericin, water and ethanol obtained in Step 4 was dried with a hot air dryer at a hot air temperature of 50 ° C. for 20 hours. As a result, 230 g of dried sericin having a sericin content of about 95% was obtained.
[0064]
  Step 5-2: 230 g of dried sericin obtained in Step 5-1 was finely pulverized and dried under reduced pressure at 42 ° C. for 15 hours using a normal vacuum pump. As a result, sericin powder having an average molecular weight of 500,000 measured by chromatography (gel permeation method) was obtained.
[0065]
  Step 6: Ultrafiltration device with a molecular weight cut off of 150,000 (Daisen Memblem Systems Model FS03-CC-FUS0181) from 47 liters of filtrate (sericin content 0.6%) that passed through the filter cloth in the filtration of Step 2 Concentrated with. As a result, 12 liters of a retentate having a sericin content of 1.4% and 35 liters of a filtrate having a sericin content of 0.3% were obtained.
[0066]
  Step 7: In 12 liters of the retentate having a sericin content of 1.4% obtained in Step 6, hydrogen peroxide is added to a concentration of 0.5% by weight, and the contained sericin is gelled. did. This retentate in which sericin is gelled is used as a filter cloth with an air permeability of 1.5 cm.³/(cm²・ S)The filtration was performed under the same filtration conditions as in Step 2, except that the woven filter cloth was used. As a result, 3.8 liters of residual liquid (concentrated liquid) having a sericin content of 3.4% and 8 liters of filtrate having a sericin content of 0.5% were obtained. The retentate obtained in step 6 may be directly charged into step 8. However, in that case, the efficiency of drying in step 8 is not good.
[0067]
  Step 8: 3.8 liters of the residual liquid (concentrated liquid) having a sericin content of 3.4% obtained in Step 7 was dried under reduced pressure at 42 ° C. for 20 hours using an ordinary vacuum pump. As a result, about 120 g of sericin powder having an average molecular weight of 150,000 measured by chromatography (gel permeation method) was obtained.
[0068]
  Step 9: Combine 8 liters of filtrate with a sericin content of 0.5% obtained in Step 7 and 35 liters of filtrate with a sericin content of 0.3% obtained in Step 6 to obtain a molecular weight cut-off of 10,000. The solution was concentrated with an ultrafiltration device (Daisen Memblem Systems Model FB02-CC-FUS0181). As a result, about 10 liters of a retentate having a sericin content of 1.2% was obtained.
[0069]
  Step 10: About 10 liters of the retentate having a sericin content of 1.2% obtained in Step 9 is heated to 42 ° C. using the vacuum concentration device 6 shown in FIG. The solution was concentrated under reduced pressure for 20 hours, and the sericin content was 50% by weight, and the concentrate was 200 cm.³was gotten. This concentrate 200cm³The vacuum drying container 14 shown in FIG. 3 is used to heat the vacuum drying container 14 to 42 ° C., the vacuum vacuum is dried for 15 hours with a normal vacuum pump, and the average molecular weight measured by chromatography (gel permeation method) is About 105 g of 60,000 sericin powder was obtained.
[0070]
  Although the embodiment of the method for purifying sericin of the present invention has been described above, the present invention can be carried out in a mode to which various improvements, modifications and variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. These embodiments all belong to the scope of the present invention.
[0071]
【The invention's effect】
  The present invention classifies from a mixture of sericin and water containing sericin having a large molecular weight of 500,000 or more, such as lower pipe waste liquid, to several molecular weight grades including a molecular weight grade of about 500,000 or more. The obtained sericin can be obtained efficiently.
[0072]
  The present invention involves the modification of sericin classified into several molecular weight grades, including sericin mainly composed of a large molecular weight sericin of about 500,000 or more, without using chemicals and chemicals from natural products. Can be obtained efficiently.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a process diagram showing the flow of steps of a method for purifying sericin according to the present invention.
2 shows an embodiment of a vacuum concentrator for vacuum concentration that can be suitably used in the present invention, FIG. 2 (a) is a plan view, and FIG. 2 (b) is a longitudinal sectional view.
3 shows an embodiment of a vacuum dryer for vacuum drying that can be suitably used in the present invention, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a longitudinal sectional view.
[Explanation of symbols]
6: Vacuum concentrator
8: Soft objects
9: Gel
10: Vacuum dryer

Claims (13)

Preparing a lower pipe waste liquid containing sericin having a molecular weight of 500,000 or more;
Purification process of sericin and a step 2 of permeability under tube effluent said is filtered through a filter cloth which is ^{1~7cm 3 / (cm 2 · S} ). The step 2, and sealing the lower tube waste in a bag comprising the filter cloth, the purification method of sericin according to claim 1 including the step of pressurizing the bag to the lower tube waste is sealed. Mixing the first filtration residue obtained in step 2 with a water-soluble organic solvent; and
Filtering the first filtration residue mixed with the water-soluble organic solvent through a second filter cloth;
The method for purifying sericin according to claim 1, further comprising a step 5 of drying the second filtration residue obtained in the step 4.   The method for purifying sericin according to claim 3, wherein the water-soluble organic solvent is ethanol.   The method for purifying sericin according to claim 3 or 4, wherein the step 5 includes a hot air drying step. The step 4 encloses the first filtration residue in a second bag comprising the second filter cloth, and the second bag in which the first filtration residue is encapsulated. The method for purifying sericin according to any one of claims 3 to 5, comprising a step of applying pressure.   The method for purifying sericin according to any one of claims 3 to 6, comprising a step 6 of ultrafiltration of the filtrate filtered in the step 2.   The method for purifying sericin according to claim 7, comprising the step 8 of drying the retentate produced in the step 6.   The method for purifying sericin according to claim 8, further comprising the step of filtering the retentate after hydrogen peroxide is added to the retentate produced in the step 6 to gel the sericin in the retentate. The sericin according to claim 9, wherein the filtration in the step 7 includes a step of filtering through a third filter cloth, and the air permeability of the third filter cloth is 1 to 7 cm ³ / ( cm ² · S ) . Purification method.   The method for purifying sericin according to any one of claims 7 to 10, further comprising a step 9 of ultrafiltration of the filtrate produced in the step 6 and / or the filtrate produced in the step 7.   The method for purifying sericin according to claim 11, comprising a step 10 of drying the retentate produced in the step 9. Step 10 is
A vacuum concentration step of concentrating the retentate produced in step 9 under reduced pressure;
The method for purifying sericin according to claim 12, further comprising a reduced-pressure drying step of drying the concentrated solution produced in the reduced-pressure concentration step under reduced pressure .

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