JPWO2015178147A1 - Fibroin porous sheet, medical sheet, wound dressing, and method for producing fibroin porous sheet - Google Patents

Abstract

Provided are a fibroin porous sheet that is thin and excellent in water absorption speed, water retention, adhesion, and preferably transparency at the time of water absorption, and a method for producing the same. Specifically, a fibroin porous sheet having a 25% compression hardness of 200 kPa to 800 kPa and a thickness of 0.25 mm to 2.5 mm, wherein at least one surface of the sheet does not have a non-porous coating over the entire surface, A medical sheet using a fibroin porous sheet, and a wound dressing using the fibroin porous sheet are provided. Furthermore, the present invention provides a method for producing a fibroin porous sheet in which a dry fibroin porous material having a 25% compression hardness of 200 kPa to 800 kPa is compressed at a compression rate of 7% to 40% and sliced with a band saw.

Description

The present invention relates to a fibroin porous sheet, a medical sheet, a wound dressing, and a method for producing a fibroin porous sheet.

  Porous materials made using biological substances such as proteins and saccharides are used in cosmetics and esthetics for the purpose of moisturizing, etc. for use in esthetic salons or individuals; medical treatments such as wound dressings and drug sustained-release carriers Field: Daily necessities such as disposable diapers and sanitary products; Water purification field that can be used as a support for microorganisms, bacteria, etc .; Cell culture support (scaffolding materials) and tissue regeneration support in tissue engineering, regenerative medical engineering, etc. It can be used in a wide range of industries such as the body.

  Protein groups such as saccharides such as cellulose and chitin, collagen, keratin, and silk fibroin are known as biologically-derived substances constituting the porous body. Among these, fibroin, particularly silk fibroin, is industrially utilized because it is excellent in stable supply of raw materials and price stability. Furthermore, it has a track record of being used for a long time as a surgical suture, in addition to clothing applications, and has recently been used as an additive for foods and cosmetics. Since silk fibroin has no problem with respect to safety to the human body, use in the field of utilization of porous materials is being studied.

  There are several reports on the technique for producing silk fibroin porous materials. For example, a method in which a silk fibroin aqueous solution is rapidly frozen and then immersed in a crystallization solvent and melted and crystallized at the same time (see Patent Document 1). A method for producing a porous body (see Patent Document 2), adding a small amount of a water-soluble organic solvent to a silk fibroin aqueous solution, and then freezing and melting for a certain time to obtain a silk fibroin porous body Techniques (see Patent Document 3 and Non-Patent Document 1) are known. Further, there is a report that a porous material having a homogeneous structure excellent in water absorption can be obtained by using a porous material such as paper on the inner wall of the container using the technique of Patent Document 3 (Patent Document). 4). Furthermore, there is a report of an example of processing a silk fibroin porous body using a slicing apparatus (see Patent Document 5).

JP-A-8-41097 JP 2006-249115 A Japanese Patent No. 3412014 JP 2008-255298 A JP 2012-82246 A

Biomacromolecules, 6, p. 3100-3106 (2005)

Since the porous body produced by the methods described in Patent Documents 1 to 3 has a non-porous film on the surface, there is room for improvement in the water absorption rate.
Moreover, the porous body produced by the technique described in Patent Document 4 is formed on the surface although a part of the non-porous film formed on the surface of the porous body is peeled off by the porous material on the surface of the container. The non-porous film cannot be completely removed, and the porous material on the surface of the container and the silk fibroin porous body are firmly fixed, so that the film is thin (for example, 2.5 mm or less, preferably thick). In the case of producing a silk fibroin porous body (having a thickness of 1 mm or less), there was a problem that it was difficult to take out without breaking from the container.
Furthermore, Patent Document 5 describes an example in which the produced porous body is processed by a slicing apparatus, but the processing accuracy is poor in processing in a water-containing state, and the 25% compression hardness is 200 kPa to 800 kPa. In the case of such a flexible porous body, there has been a problem that processing into a thin sheet (for example, a thickness of 2.5 mm or less, preferably 1 mm or less) is extremely difficult.
For example, in the case of a wound dressing, a sufficient water absorption speed and water retention are required even in the case of a thin sheet.
Therefore, the present invention provides a thin fibroin porous sheet that has no non-porous coating over the entire surface of at least one surface of the sheet and is excellent in water absorption rate, water retention and adhesion, and a medical device using the fibroin porous sheet. It is an object of the present invention to provide a wound sheet, a wound dressing material using the fibroin porous sheet, and a method for producing the fibroin porous sheet.

As a result of intensive studies to achieve the above problems, the present inventors have found that the problems can be solved by the following invention.
That is, the present invention relates to the following [1] to [16].
[1] A fibroin porous sheet having a 25% compression hardness of 200 kPa to 800 kPa and a thickness of 0.25 mm to 2.5 mm, wherein at least one surface of the sheet does not have a non-porous coating over the entire surface.
[2] The fibroin porous sheet according to the above [1], wherein the thickness is 0.25 mm to 1 mm.
[3] The fibroin porous sheet according to the above [1] or [2], wherein both surfaces of the sheet do not have a non-porous film over the entire surface.
[4] The fibroin porous sheet according to any one of the above [1] to [3], wherein the area ratio of the pores is 60% to 99% on the surface having no non-porous film over the entire surface.
[5] the area of the sheet is a 15cm ² ~1200cm ^2, fibroin porous sheet according to any one of the above [1] to [4].
[6] The above [1] to [5], wherein the positive thickness variation represented by the following formula (1) and the negative thickness variation represented by the following formula (2) are both within 15%. The fibroin porous sheet according to any one of the above.
Positive thickness variation (%) = {(maximum thickness (mm)) / (average thickness (mm)) × 100} −100 (1)
Negative thickness variation (%) = 100 − {(minimum thickness (mm)) / (average thickness (mm) × 100} (2)
[7] The fibroin porous sheet according to any one of the above [1] to [6], which contains a hydroxyl group-containing compound.
[8] The fibroin porous sheet according to the above [7], wherein the hydroxyl group-containing compound is glycerin.
[9] The fibroin porous sheet according to any one of [2] to [8], wherein the color difference is 0.50 to 7.94.
[10] The fibroin porous sheet according to any one of [2] to [9], wherein the color difference per unit thickness is 2.1 to 7.8.
[11] The fibroin porous sheet according to any one of [1] to [10], wherein the fibroin is silk fibroin.
[12] A medical sheet comprising the fibroin porous sheet according to any one of [1] to [11].
[13] A wound dressing comprising the fibroin porous sheet according to any one of [1] to [11].
[14] A method for producing a fibroin porous sheet, comprising compressing a dry fibroin porous material having a 25% compression hardness of 200 kPa to 800 kPa at a compression rate of 7% to 40% and slicing with a band saw.
[15] The method for producing a fibroin porous sheet according to the above [14], wherein the dry fibroin porous material contains 20% by mass to 60% by mass of a hydroxyl group-containing compound.
[16] The method for producing a fibroin porous sheet according to the above [14] or [15], wherein the dried fibroin porous material is a silk fibroin porous material.

  The porous sheet according to the present invention is a thin sheet having a thickness of 0.25 mm to 2.5 mm, which is difficult to produce despite being flexible with a 25% compression hardness of 200 kPa to 800 kPa. And at least one surface of a sheet does not have a non-porous film over the whole surface. Therefore, although it is thin, it is excellent in water absorption speed and water retention, and is excellent in adhesion. Furthermore, the porous sheet according to the present invention includes those having excellent transparency at the time of water absorption.

It is an example of the slicing apparatus used for the slice of a porous body. It is an example of the other slice apparatus used for the slice of a porous body. It is a figure which shows a compression rate. It is a figure which shows the height distance of an upper roll and a band saw. It is a figure which shows the measuring point of thickness. It is an electron micrograph of the non-porous film | membrane of the surface of a silk fibroin porous body. It is an electron micrograph of the slice surface of the silk fibroin porous body from which the non-porous film of the surface was excised by slicing. It is a figure which shows the thickness measurement point of the comparative example 12.

(Fibroin porous sheet)
The fibroin porous sheet according to the present invention has a non-porous coating on at least one surface of the sheet, a 25% compression hardness of 200 kPa to 800 kPa, and a thickness of 0.25 mm to 2.5 mm. It is a fibroin porous sheet. It is preferable that both surfaces of the sheet, that is, both the front surface and the back surface do not have a non-porous film over the entire surface. Here, “there is no non-porous coating over the entire surface” means a state in which pores exist in any section when the surface of interest is divided into 25 cm vertically and horizontally at an arbitrary length of 5 cm × 5 cm. .
Since at least one surface of the sheet does not have a non-porous film over the entire surface, the water absorption rate and moisture retention are excellent, and since the thickness is as thin as 0.25 to 2.5 mm, the adhesion is excellent. In particular, when the thickness is 1 mm or less, the transparency at the time of water absorption is excellent. In addition, since it becomes difficult to process by giving flexibility by setting the 25% compression hardness to 800 kPa or less, it is usually difficult to make the thickness 2.5 mm or less. I am letting.
Normally, the fibroin porous body has a non-porous coating on the entire surface thereof, but as described above, the fibroin porous sheet of the present invention does not have a non-porous coating on the entire surface of at least one of the sheets. The method for producing the fibroin porous sheet of the present invention will be described in detail later. For example, it can be obtained by processing a dry fibroin porous material containing a hydroxyl group-containing compound.

  The thickness of the fibroin porous sheet of the present invention is 0.25 mm to 2.5 mm. If the thickness of the sheet is 0.25 mm or more, the silk fibroin porous sheet has sufficient strength and can be handled and processed. On the other hand, if the sheet thickness is 2.5 mm or less, the adhesiveness is excellent, and if it is 1 mm or less, the transparency at the time of water absorption is also excellent. From the same viewpoint, the thickness of the fibroin porous sheet is preferably 0.25 mm to 2.0 mm, more preferably 0.25 mm to 1 mm, and further preferably 0.4 mm to 0.8 mm.

On the surface of the fibroin porous sheet of the present invention which does not have a non-porous coating, the pore area ratio is preferably 60% to 99%, more preferably 80% to 99%, and even more preferably 85% to 98. %. When the pore area ratio is 60% or more, the water absorption rate, water retention and adhesion tend to be sufficient, and when it is 99% or less, sufficient water retention tends to be maintained. The area ratio is measured by subjecting a scanning electron micrograph to image processing using image analysis software ImageJ (manufactured by National Institutes of Health, USA).
Further, the pore size (average pore diameter) of the fibroin porous sheet is preferably 1 μm to 300 μm, more preferably 5 μm to 200 μm, still more preferably 10 μm to 100 μm, and particularly preferably 15 μm to 50 μm.
Furthermore, the porosity is preferably 80% or more, more preferably 90% or more, and further preferably 95% or more. Here, the porosity is a value obtained as follows. First, the obtained porous body is left in pure water for 1 day to completely absorb water, weighed (wet mass), freeze-dried to completely remove water in the porous body, and weighed again. (Dry mass). Next, assuming that the density of water is 1 g / cm ³ , the density of fibroin is 1.2 g / cm ³ , and the density of the fibroin porous material in a water-containing state is 1 g / cm ³ , the value obtained according to the following equation is the silk fibroin porosity. The porosity of the material was taken.
Porosity = {(wet mass−dry mass / 1.2) / wet mass} × 100

Also, the area of fibroin porous sheet of the present invention may be suitably determined in accordance with the application is not particularly ^limited, is preferably a 15cm ² ~1200cm 2. Within this range, it is easy to use for each application such as face mask, eye mask, wound dressing and the like. From the above viewpoint, it is more preferable area of fibroin porous sheet is 15cm ² ~1000cm ^2.
It should be noted that processing a thin fibroin porous sheet such as 0.25 mm to 2.5 mm in such a size while suppressing variation in thickness is difficult in the usual method, coupled with the difficulty in processing the fibroin porous body. This is difficult and has been achieved for the first time by processing by the method described in detail later.

The positive thickness variation and the negative thickness variation of the fibroin porous sheet of the present invention are both preferably within 15%, and more preferably within 10%. The thickness variation is determined by the following method.
(Thickness variation)
As shown in FIG. 5, the thickness of 12 points of the sheet was measured, and the thickness variation was calculated from the maximum value, the minimum value, and the average value according to the following equation.
Positive thickness variation (%) = {(maximum thickness (mm)) / (average thickness (mm)) × 100} −100 (1)
Negative thickness variation (%) = 100 − {(minimum thickness (mm)) / (average thickness (mm) × 100} (2)
These thickness variations are preferably as small as possible, but in particular if they are 15% or less, there is an advantage that the thinned portion during processing is not easily broken. In addition, there is an advantage that adhesion at a thick portion is difficult to be lowered and is not easily peeled off during mounting. From the above viewpoint, the thickness variation is more preferably 10% or less.
The lower limit of the thickness variation is preferably as small as described above, but is about 1% in manufacturing.

  The fibroin porous sheet of the present invention preferably contains a hydroxyl group-containing compound. By containing the hydroxyl group-containing compound in the manufacturing process of the fibroin porous sheet described in detail later, while suppressing the occurrence of cracks due to freeze-drying, to suppress a crack during processing by giving a certain degree of flexibility, In addition, a sheet having a 25% compression hardness of 200 kPa to 800 kPa can be obtained.

The hydroxyl group-containing compound may be any compound having one or more hydroxyl groups per molecule, preferably having 1 to 10 hydroxyl groups per molecule, and more preferably having 1 to 4 hydroxyl groups per molecule. Those having 2 to 4 hydroxyl groups per molecule are more preferred.
The molecular weight of the hydroxyl group-containing compound is preferably 1000 or less, more preferably 800 or less, more preferably 500 or less, further preferably 200 or less, and particularly preferably 150 or less. preferable. On the other hand, the lower limit of the molecular weight of the hydroxyl group-containing compound is not particularly limited, but is preferably 30 or more, more preferably 50 or more, and further preferably 70 or more.

Specific examples of the hydroxyl group-containing compound include glycerin, polyglycerin, polyethylene glycol, triethyl citrate, lactic acid, polyvinyl alcohol, propylene glycol, butylene glycol, alcohol, glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, and the like. Can be mentioned. Among these, 1 type can be used independently or 2 or more types can be used together.
Among these, glycerin, polyethylene glycol, triethyl citrate, polyglycerin, lactic acid, propylene glycol, and butylene glycol are preferred from the viewpoints of handling properties, slice processability, and safety. In particular, since glycerin has an effect of moisturizing the skin, it is more preferable in applications where it is applied to the skin such as skin care materials and wound dressings.

The color difference of the fibroin porous sheet of the present invention is not particularly limited, but the color difference is preferably 0.50 to 7.94. The color difference is a value obtained by the measurement method described in the examples. If the color difference is 0.50 or more, it is advantageous in that the sheet can be easily seen, and if the color difference is 7.94 or less, the color change is small when applied to the skin, so that the face, arms or legs It is advantageous in that it can easily relieve a sense of incongruity when it is attached to the like. From the above viewpoint, the color difference of the fibroin porous sheet is more preferably 0.5 to 5.0, and still more preferably 0.8 to 5.0.
The color difference per unit thickness is not particularly limited, but is preferably 2.1 / mm to 7.8 / mm. If the color difference per unit thickness is 2.1 / mm or more, it is advantageous in that the sheet is easily visible, and if it is 7.8 / mm or less, the color change is small when applied to the skin. It is advantageous in that it is easy to relieve a sense of discomfort when worn on the face, arms or feet. From the above viewpoint, the color difference per unit thickness is more preferably 2.1 / mm to 5.0 / mm, and further preferably 2.5 / mm to 5.0 / mm.

  The fibroin constituting the fibroin porous sheet of the present invention is preferably silk fibroin from the viewpoint of obtaining excellent water absorption rate, excellent water retention, flexibility, texture and the like.

(Fibroin porous sheet manufacturing method)
The fibroin porous sheet of the present invention can be obtained by processing a fibroin porous material. Specifically, it is obtained by compressing a dry fibroin porous material having a 25% compression hardness of 200 kPa to 800 kPa at a compression rate of 7% to 40% and slicing with a band saw. Hereinafter, the manufacturing method of a fibroin porous sheet is demonstrated in detail.

<Fibroin porous material>
The fibroin porous body is not particularly limited as long as it is a porous body composed of fibroin. From the viewpoint of obtaining excellent water absorption speed, excellent water retention, flexibility, texture, etc., it is a silk fibroin porous body. Preferably there is.
The fibroin porous material is obtained by, for example, freezing a fibroin aqueous solution in which additives such as carboxylic acids, amino acids, and water-soluble liquid organic substances are added to a fibroin aqueous solution to obtain a frozen material, and then frozen water in the frozen material. A technique obtained by melting is used. According to this technique, a fibroin porous body excellent in shape stability and strength tends to be obtained.

  Examples of fibroin include silk fibroin produced from natural silkworms such as rabbits, wild silkworms, and tengu, and transgenic silkworms. In consideration of the simplicity of the production process, silk fibroin obtained from rabbit cocoons is preferred. Hereinafter, silk fibroin will be described as an example, but the present invention is not limited thereto.

(Silk fibroin porous material)
The silk fibroin used as a raw material for the silk fibroin porous material may be any one as long as it is produced from silkworms such as rabbits, wild silkworms, and tengu, as described above, and the production method thereof is not limited. The silk fibroin porous material is obtained from a silk fibroin solution, but when dissolved in water, silk fibroin has low solubility in water and is difficult to directly dissolve in water. As a method for obtaining a silk fibroin aqueous solution, any known method may be used, but a method in which silk fibroin is dissolved in a high concentration lithium bromide aqueous solution, followed by desalting by dialysis and concentration by air drying is simple.

The silk fibroin porous material used in the present invention may be produced by any method, but due to reproducibility and high strength of the obtained porous material, a specific additive is added to the silk fibroin aqueous solution to obtain the aqueous solution. It is preferred to produce by freezing and then thawing.
In the production of the silk fibroin porous body, the concentration of silk fibroin is preferably 1 to 10% by mass / volume, more preferably 1.5 to 8% by mass / volume in the silk fibroin solution. More preferably, it is 0.0-6 mass / volume%. By setting within this range, it is possible to efficiently produce a silk fibroin porous body that has sufficient strength and is difficult to break during slicing.

<Additives>
Examples of the additive include carboxylic acids, amino acids, water-soluble liquid organic substances, and the like. These additives can be used individually by 1 type, or can also use 2 or more types together.

The carboxylic acids are not particularly limited as long as they are organic acids having at least one carboxy group in the molecule, and examples thereof include monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids. Moreover, the thing whose pKa is 5.0 or less is preferable, the thing of 3.0-5.0 is more preferable, and the thing of 3.5-5.0 is further more preferable.
As the carboxylic acids, aliphatic carboxylic acids are preferable, and for example, saturated or unsaturated monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids having 1 to 6 carbon atoms can be preferably used. Specific examples include formic acid, acetic acid, propionic acid, butyric acid, succinic acid, lactic acid, acrylic acid, 2-butenoic acid, and 3-butenoic acid. These aliphatic carboxylic acids can be used individually by 1 type, or can use 2 or more types together. Among these, from the viewpoint of safety to the human body, acetic acid, lactic acid, and succinic acid are more preferable, and acetic acid is more preferable.

The amino acid is not particularly limited, and examples thereof include monoaminocarboxylic acids such as valine, leucine, isoleucine, glycine, alanine, serine, threonine, and methionine; monoaminodicarboxylic acids (acidic amino acids) such as aspartic acid and glutamic acid. Aliphatic amino acids are mentioned. In addition, aromatic amino acids such as phenylalanine and amino acids having a heterocyclic ring such as hydroxyproline are also included. Among these, acidic amino acids and oxyamino acids such as hydroxyproline, serine and threonine are preferable from the viewpoint of ease of shape adjustment.
From the same viewpoint (easily adjusting the shape), monoaminodicarboxylic acid is more preferable among acidic amino acids, aspartic acid and glutamic acid are particularly preferable, and hydroxyproline is more preferable among oxyamino acids. These amino acids can be used alone or in combination of two or more.
Amino acids include L-type and D-type optical isomers, but when L-type and D-type are used, there is no difference in the resulting porous material. Good.

  The water-soluble liquid organic substance is liquid at normal temperature (20 ° C.), and is dissolved or mixed without separation when mixed with water at normal temperature (20 ° C.). Examples of water-soluble liquid organic substances include alcohols such as methanol, ethanol, isopropanol, and butanol; polyhydric alcohols such as glycerin and propylene glycol; dimethyl sulfoxide (DMSO); dimethylformamide (DMF); pyridine; acetone; Etc. are preferred. These can be used individually by 1 type or can use 2 or more types together. Among these, it is preferable to use ethanol, dimethyl sulfoxide, glycerin, and acetone from the viewpoint of safety to the human body.

When the additive is used in the silk fibroin aqueous solution, the content of the additive is preferably 0.1 to 18% by volume, more preferably 0.1 to 5.0% by volume, More preferably, it is 4.0 volume%. By setting within this range, it tends to be easy to manufacture a porous body having sufficient strength.
Moreover, it is preferable that content of an amino acid is 1-500 mass parts with respect to 100 mass parts of silk fibroin, It is more preferable that it is 5-50 mass parts, It is further 10-30 mass parts preferable.

The silk fibroin porous material to which the additive is added can be produced by pouring the silk fibroin solution to which the additive has been added into a mold or a container, freezing it in a low-temperature thermostatic bath, and then thawing it. it can. The freezing temperature is not particularly limited as long as the silk fibroin solution containing the additive is frozen, but is preferably −30 ° C. to −10 ° C., more preferably −25 ° C. to −15 ° C. Further, the freezing time is preferably 4 hours or more at a predetermined freezing temperature so that it can be sufficiently frozen and kept in a frozen state for a certain time.
As a method of freezing, the silk fibroin solution may be frozen to a freezing temperature all at once, but once it is kept at about −5 ° C. for about 2 hours to be in a supercooled state and then lowered to the freezing temperature. Freezing is preferable for obtaining a porous body having high mechanical strength. In addition, the structure and strength of the porous body can be controlled to some extent by adjusting the time taken from −5 ° C. to the freezing temperature.
Thereafter, the silk fibroin porous material is obtained by thawing the frozen silk fibroin solution. The melting method is not particularly limited, and examples include natural melting and a method of holding in a thermostatic bath.

  The silk fibroin porous material thus obtained contains additives, but if it is necessary to remove the additives depending on the application, the additives are removed from the silk fibroin porous material by an appropriate method. Can be used. For example, the simplest method is to remove the additive by immersing the silk fibroin porous material in pure water or ultrapure water.

The silk fibroin porous body has a sponge-like porous structure. Normally, this silk fibroin porous body contains water unless it is removed by drying, and is a flexible structure in a water-containing state. is there.
On the other hand, a dried silk fibroin porous material can be obtained by drying the silk fibroin porous material. Although there is no restriction | limiting in particular in a drying method, From a viewpoint of suppressing the shrinkage | contraction accompanying drying, freeze-drying is preferable. In the case of freeze-drying, if the drying is completed without completely sublimating the water, the pores are crushed due to the surface tension of the remaining water. Therefore, it is preferable to dry until the water is completely sublimated.

<Introduction of hydroxyl-containing compound>
It is preferable that the silk fibroin porous material contains the hydroxyl group-containing compound before the lyophilization. By containing the hydroxyl group-containing compound, cracking due to freeze-drying is suppressed, cracking during processing is suppressed by giving a certain degree of flexibility, and 25% compression hardness is 200 kPa to 800 kPa. A flexible sheet can be obtained.
A silk fibroin porous material having a hardness suitable for slicing can be obtained by drying by the above method. On the other hand, when wet, the processing accuracy tends to be low because it is too soft during processing, and when the silk fibroin porous body is pressed against the slicing blade, the water inside the silk fibroin porous body is squeezed out. This tends to make it difficult to process.
In addition, when the silk fibroin porous sheet wet with water or a cosmetic liquid is required, it can be easily wetted by being immersed in water or a cosmetic liquid after processing.

  The method for containing the hydroxyl group-containing compound in the silk fibroin porous body is not particularly limited, and when the silk fibroin porous body is produced, the method of blending it into the silk fibroin solution, You may make it soak in the solution containing the hydroxyl-containing compound of the grade which immerses. Although the immersion time is not particularly limited, if the immersion time is short, the amount of the hydroxyl group-containing compound introduced into the silk fibroin porous material is small, or the concentration varies depending on the place in the silk fibroin porous material. Problems can occur.

In the silk fibroin porous body containing a hydroxyl group-containing compound, the content of the hydroxyl group-containing compound is preferably 20 to 60% by mass, more preferably 25 to 50% by mass, and 25 to 45% by mass. More preferably. By setting the concentration of the hydroxyl group-containing compound within the above range, a silk fibroin porous material excellent in flexibility, workability, and handling properties tends to be easily obtained. More specifically, when it is 20% by mass or more, it is excellent in flexibility, is not easily cracked when dried, does not become brittle, is not easily cracked during slicing, and excellent handling properties tend to be obtained. On the other hand, when it is 60% by mass or less, moderate flexibility can be suppressed, shrinkage before and after lyophilization is small, the tack of the surface of the porous material is good, and it is difficult to wind around the roll during slicing, Excellent handling properties tend to be obtained.
Moreover, in the said range, the hardness of the porous material obtained can be adjusted by changing a hydroxyl-containing compound density | concentration. For example, when a porous material having a hydroxyl group-containing compound concentration of 20% by mass and a porous material of 40% by mass are compared, the porous material of 40% by mass is more flexible.

  The silk fibroin porous material can be made into a shape suitable for the purpose, such as a film shape, a sheet shape, a block shape, a tubular shape, a spherical shape, and the like by appropriately selecting a mold and a container for producing the silk fibroin porous material. In view of the ease of slicing, it is preferable to use a sheet-like material having no irregularities. There are no restrictions on the shape or container of the silk fibroin solution so long as it does not flow out. From the viewpoint of obtaining a silk fibroin porous body having a uniform structure, the material is iron, stainless steel, aluminum, gold, or the like. It is preferable to use a material having high thermal conductivity such as silver, copper and the like. Further, the thickness of the mold and the wall of the container is preferably 0.5 mm or more from the viewpoint of its function and deformation due to expansion during freezing, etc., and it is easy to handle and has cooling efficiency. From the viewpoint, it is more preferably 1 to 3 mm.

Moreover, the mold | type and container used here can provide a mold release layer in the inner wall surface in contact with the silk fibroin solution inside for the purpose of prevention of adhesion | attachment of a silk fibroin porous body.
For the release layer, a sheet made of a fluororesin such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA); Preferable examples include a release-treated sheet made of polyethylene terephthalate (PET), polypropylene (PP) or the like; a coating made of a fluororesin such as PTFE, FEP, or PFA. When these release layers are used, the silk fibroin porous material can be easily taken out from the container.
In addition, the thickness of the release layer is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 200 μm or less, from the point that heat conduction is hardly inhibited.

The silk fibroin porous sheet can be obtained by slicing the silk fibroin porous body following the drying step described above.
As a slicing method used for manufacturing the fibroin porous sheet of the present invention, for example, as shown in FIG. 1, a silk fibroin porous material sandwiched between upper and lower rolls is sliced against a band saw, FIG. As shown in Fig. 4, there is a method of slicing by fixing the fibroin porous body with a suction chuck or a frictional force and moving the blade in the horizontal direction. By performing slicing by these methods, a thin fibroin porous sheet having excellent adhesion can be obtained with high thickness accuracy. Moreover, the fibroin porous sheet excellent in the transparency at the time of water absorption is obtained by making thickness into 1.0 mm or less.
Further, in the slicing process, it is preferable from the viewpoint of water absorption speed and transparency to excise a non-porous film formed on at least one surface, preferably the entire surface, of the silk fibroin porous body. Hereinafter, a method for slicing the silk fibroin porous material sandwiched between the upper and lower rolls shown in FIG.

The device for slicing the silk fibroin porous material sandwiched between the upper and lower rolls shown in FIG. 1 to the band saw has a band saw rotating between the upper and lower rolls whose vertical position can be adjusted. The transported silk fibroin porous material is fed between upper and lower rolls, pressed against a rotating band saw, and cut to obtain a fibroin porous sheet. This apparatus can obtain a fibroin porous sheet having an arbitrary thickness by adjusting the positions of the upper and lower rolls. In addition, by setting the preferred compression ratio and the height distance between the upper roll and the band saw, it is possible to obtain a fibroin porous sheet that is thin, excellent in adhesion and in some cases transparency at the time of water absorption, with high thickness accuracy. it can.
As described above, the positive thickness variation and the negative thickness variation of the silk fibroin porous sheet are each preferably 15% or less, and more preferably 10% or less. By using a silk fibroin porous material having a preferable hardness and slicing it by setting a preferable compression ratio and a height distance between the upper roll and the band saw, such a silk fibroin porous sheet having a small thickness variation can be obtained. can get. The compression rate and the height distance between the upper roll and the band saw are defined as shown in FIGS. 3 and 4, respectively. That is, when the thickness of the silk fibroin porous sheet is “A” and the distance between the upper roll and the lower roll is “B”, the compression ratio is (A−B) / A [however, when% is displayed, Multiply by 100. ] (See FIG. 3). Further, the height distance between the upper roll and the band saw is defined as the distance from the intersection of the straight line indicating the shortest distance between the upper roll and the lower roll and the extension line of the tip of the band saw blade to the upper roll (see FIG. 4). ).

As described above, the hardness of the silk fibroin porous material subjected to slicing is such that the 25% compression hardness is 200 kPa to 800 kPa, preferably 250 kPa to 800 kPa, and more preferably 300 kPa to 600 kPa. When the 25% compression hardness is 200 kPa or more, the processing accuracy is improved, and slice processing to a thickness of 2.5 mm or less is facilitated. When the 25% compression hardness is 800 kPa or less, the porous body can be prevented from cracking during slicing, and sufficient flexibility can be obtained.
In addition, since the 25% compression hardness of the silk fibroin porous sheet obtained by slicing a silk fibroin porous body having a 25% compression hardness in the above range is composed of the same porous body, The value is equivalent to the above.

Although there is no restriction | limiting in particular in the thickness of the silk fibroin porous body used for a slice process, It is preferable that it is 1 mm-50 mm, It is more preferable that it is 2 mm-40 mm, It is further more preferable that it is 2.5 mm-20 mm. By using a porous body having a thickness in this range, it can be processed with high accuracy.
Although there is no restriction | limiting in particular in the shape of the silk fibroin porous body provided to a slicing process, When it is the objective to obtain a silk fibroin porous sheet, it is preferable that it is a shape which has two flat sides. Specifically, a rectangular parallelepiped, a cube, a cylinder, a triangular prism, etc. are mentioned.

The compression rate in slicing is 7 to 40%, preferably 10 to 40%, and more preferably 10 to 30%. The compression rate is calculated from the thickness of the silk fibroin porous body before slicing and the set distance between the upper and lower rolls of the slicing machine as shown in the following equation.
Compression rate = {(silk fibroin porous body thickness−distance between upper and lower rolls) / silk fibroin porous body thickness} × 100
When the silk fibroin porous body is compressed at a compression rate exceeding 40%, the silk fibroin porous body is crushed by the upper and lower rolls, and the shape cannot be maintained. Further, when the silk fibroin porous body is compressed at a compression rate of less than 7%, the upper and lower rolls cannot be sandwiched between the silk fibroin porous body, and the silk fibroin porous body that hits the band saw flows in the rotation direction of the band saw. Therefore, it cannot be sliced.

  As described above, for example, by using a dry silk fibroin porous material having an appropriate hardness (25% compression hardness 200 kPa to 800 kPa) obtained by adding a hydroxyl group-containing compound to the silk fibroin porous material, the compressibility , And by slicing with the above band source slicer appropriately adjusted the distance between the upper roll and the band saw, for the first time, it has a thin thickness of 0.2 to 2.5 mm and a non-porous coating on at least one surface It became possible to process into a silk fibroin porous sheet without it. Also, variation in thickness within the sheet is minimized by using a dry silk fibroin porous material with appropriate hardness, and setting the compression rate and the distance between the upper roll and the band saw to appropriate values. can do.

  In slicing, the height distance between the upper roll and the band saw is preferably 0.2 mm to 1.0 mm, and more preferably 0.2 mm to 0.9 mm. By setting within this range, a thin sheet can be sliced with low thickness variation.

In order to excise the non-porous film on the surface of the silk fibroin porous material by slicing, at least one surface, preferably two surfaces of the silk fibroin porous material having the non-porous film may be excised by slicing. is necessary. When slicing for the purpose of excision of the non-porous film of the silk fibroin porous material, the thickness to be excised is not particularly limited as long as the non-porous film can be removed, but it is 0.1 mm to 2 mm. Is preferably 0.2 mm to 1.5 mm, and more preferably 0.3 mm to 1 mm.
Usually, a silk fibroin porous body has a non-porous film on the entire surface thereof, but it is not necessary to remove the non-porous film by slicing all of the non-porous film. For example, after slicing two opposite faces of a rectangular parallelepiped and removing the non-porous film, the entire surface of the non-porous film is removed by further punching or manual cutting. A fibroin porous sheet can also be obtained.
However, since it is difficult to punch or manually process a wide surface with high processing accuracy, it is preferable to perform the slicing when removing a non-porous film having an area of at least 20 cm ² or more. Moreover, there is no restriction | limiting in particular in the order of a process, For example, a slicing process may be performed after a punching process and vice versa.
There is no restriction | limiting in particular in the method of punching, For example, the punching by the hand press which uses a Thomson blade, or a hydraulic press is mentioned.

When slicing is performed, there is no particular limitation on the number of sheets produced from one porous body.
For example, if both surfaces of the sheet are silk fibroin porous sheets that do not have a non-porous coating, the non-porous coating is cut from the entire surface of a single silk fibroin porous material to obtain a single silk fibroin porous sheet. A manufacturing method can be used. In addition, 10 mm-thick rectangular parallelepiped silk fibroin porous bodies are sliced 1 mm each, and after removing the non-porous film, the remaining two-sided non-porous film is removed and the 8 mm-thick rectangular parallelepiped is removed. 8 sheets of 1 mm thick silk fibroin porous sheet having no non-porous coating on the two opposite faces are obtained by slicing a 1 mm silk fibroin porous sheet 7 times from the silk fibroin porous body of For example, a method of obtaining eight 1 mm thick silk fibroin porous sheets having no non-porous film on the entire surface by punching with a Thomson blade or the like from the surface from which the non-porous film has been removed may be mentioned.
Further, when obtaining a plurality of silk fibroin porous sheets from one silk fibroin porous body in this way, there is no particular limitation on the order of slicing, and for example, slicing may be performed one by one in order from the top. Alternatively, slice processing may be performed alternately.

Usually, a silk fibroin porous sheet has a non-porous film on both sides thereof, but a silk fibroin porous sheet characterized by having no non-porous film on both surfaces of the sheet by slicing as described above. Can be obtained. Moreover, the silk fibroin porous sheet from which the non-porous film of the whole surface was removed can be obtained by performing a punching process further.
Also, a wet porous body is usually too flexible to be processed into a thin sheet, but if it is a dry silk fibroin porous body containing a hydroxyl group-containing compound, the thickness can be increased by slicing. Processing into a thin sheet of 0.25 mm to 2.5 mm is possible. In addition, such a thin sheet, particularly a sheet having a thickness of 1 mm or less, can be suitably used for applications in which transparency at the time of water absorption is high and transparency can be utilized. For example, in skin care material applications such as face masks and eye masks and medical applications such as wound dressings, it is preferable because the sheet does not stand out when worn and there is no sense of incongruity.
Since the fibroin porous sheet of the present invention is thin as described above, it is flexible, easily follows a wound part, and is easy to use on a curved surface having a high curvature such as a fingertip part. Moreover, since the non-porous film which existed on both surfaces of the fibroin porous body is removed by processing, the pores are exposed despite being thin. Therefore, the water absorption speed is high, the exudate from the wound part can be absorbed quickly, the surrounding skin or the like is hardly excessively softened, and an appropriate moist environment can be maintained. Furthermore, since the fibroin porous sheet of the present invention is also excellent in water retention, a large amount of leachate can be retained even if it is thin. Therefore, this invention also provides the medical sheet | seat formed using the fibroin porous sheet of this invention. The present invention also provides a wound dressing using the fibroin porous sheet of the present invention.

(Medical sheet, wound dressing)
The medical sheet and wound dressing of the present invention are made using the fibroin porous sheet of the present invention.
When using a fibroin porous sheet as a wound dressing, in addition to alleviating pain by sticking to the wound part, it absorbs exudate that exudes from the wound and holds it on the wound surface and is contained in the exudate It is also desirable to have water retention so that it can be used for wet therapy to heal wounds by actively utilizing the ingredients.
The fibroin porous sheet of the present invention is excellent in adhesion, without impairing the merits of texture such as flexibility and touch, and also excellent in water absorption speed and water retention.
Therefore, the medical sheet and wound dressing of the present invention alleviate the pain caused by being applied to the wound part, absorb the exudate exuding from the wound or the like and hold it in the wound part, and the exudate It is excellent in the characteristics that can actively utilize the components contained in it, and the characteristics that can be used in moving parts such as arms and elbows, and can be suitably used in wet therapy.

  The medical sheet and the wound dressing of the present invention can contain a drug by taking advantage of the excellent water absorption rate. By including a drug, the medical sheet and wound dressing of the present invention can be given a function of promoting wound healing. In the case of including a drug, for example, a drug such as a bactericide, antibiotic, or physiologically active substance may be impregnated or applied to the medical sheet or wound dressing of the present invention. These drugs can be used alone or in combination of two or more.

The medical sheet and wound dressing of the present invention can be configured such that the fibroin porous sheet of the present invention is fixed with a dressing film, bandage, adhesive tape or the like.
Since the fibroin porous sheet is soft even in a dry state, it can be used as it is as a medical sheet and a wound dressing, or it can be used as a medical sheet and a wound dressing containing a moisturizing agent. Examples of the humectant include glycerin, polyvinyl pyrrolidone, polyvinyl alcohol, and polyethylene glycol. In the case of a medical sheet or wound dressing containing a moisturizing agent, keep the medical sheet or wound dressing in a sealed state and keep it dry until just before use. Is preferred.

The medical sheet and wound dressing of the present invention are preferably composed only of the fibroin porous sheet of the present invention, and the porous layer composed of the fibroin porous sheet of the present invention and a fine layer on one surface. It is also preferable that it consists of a film layer which does not have a hole. As its usage, it is preferable that a porous layer (a surface not having a non-porous film) is in contact with the wound surface and a film layer is formed on the opposite surface opposite to the wound surface. This is because, when such a wound dressing is applied to wet therapy, exudate from the wound surface can be absorbed and retained, and there is an effect of suppressing evaporation and diffusion of the exudate.
Furthermore, as described above, by including a drug in the porous layer, it is possible to have a function of promoting wound healing. For example, healing can be promoted by impregnating or applying a bactericidal agent, antibiotics, physiologically active substance, or the like to the porous layer. These drugs can be used alone or in combination of two or more.
In addition, the number of pores of the film layer can be controlled, and a film layer having a small amount of pores can be formed as necessary.
On the other hand, since the film layer has very few pores, the surface is smooth. Therefore, by using the film layer as the wound surface side, it is possible to give a function of preventing adhesion and to control the liquid permeability of the film layer to control the drug release rate.

When the wound dressing material of the present invention is composed of the porous layer and a film layer having no pores on both sides, the rate of absorbing exudate from the wound surface as described above may be reduced. However, it has a function of suppressing evaporation of exudate and a function of preventing adhesion to the wound surface, which is useful.
Further, when the wound dressing of the present invention is composed of only a porous layer, it is assumed that exudate from the wound surface passes through the porous layer and exudes to the opposite side. Since the porous material itself has sufficient water retention, the covering material sufficiently exhibits the effects of the present invention and is useful. Evaporation can also be suppressed by using a dressing film with low moisture permeability.

EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
Example 1
(Preparation of silk fibroin solution)
The silk fibroin aqueous solution was obtained by dissolving scoured sashimi (manufactured by Nagasuna Coffee Co., Ltd.) in a 9M lithium bromide aqueous solution, removing insolubles by centrifugation, and then repeating dialysis against ultrapure water. . The obtained silk fibroin aqueous solution was air-dried in a dialysis tube and concentrated. Acetic acid was added as an additive to this concentrated solution to prepare a silk fibroin solution having a silk fibroin concentration of 3 mass / volume% and an acetic acid concentration of 2 volume%.

(Manufacture of silk fibroin porous material)
This silk fibroin solution is poured into a mold (inside size: 400 mm × 300 mm × 10 mm) made of an aluminum plate and placed in a liquid-cooled low-temperature thermostatic chamber (manufactured by Maekawa Seisakusho Co., Ltd.) that has been cooled to −5 ° C. It left still at -5 degreeC for 2 hours. Nybrine Z1 (manufactured by Maruzen Petrochemical Co., Ltd.) was used as the refrigerant.
Thereafter, it was cooled to −20 ° C. at a rate of −3 ° C./hour, and kept at that temperature for 5 hours to freeze.
The frozen sample was returned to room temperature by natural thawing, then removed from the mold, immersed in ultrapure water, and the acetic acid used was removed by exchanging the ultrapure water twice a day for 3 days.

(Introduction of hydroxyl group-containing compound (glycerin))
The silk fibroin porous material produced as described above was immersed in a 10 L 2% by volume glycerin aqueous solution for 96 hours, and then immersed in a freeze dryer “FD-550P” (model number, Tokyo Rika Instrument Co., Ltd.). And dried for 3 days to obtain a dried silk fibroin porous material. Further, the mass of the dried silk fibroin porous material was measured.
The concentration of the hydroxyl group-containing compound in the dried silk fibroin porous material is calculated by dividing the amount of the hydroxyl group-containing compound introduced into the dried silk fibroin porous material by the dry mass of the porous material after introduction of the hydroxyl compound, and Calculated.
{(Mass of dry silk fibroin porous body after introduction of hydroxyl compound)-(Mass of dry silk fibroin porous body without introduction of hydroxyl group-containing compound)} / (Mass of dry silk fibroin porous body after introduction of hydroxyl compound)

(Slicing)
The silk fibroin porous material produced as described above is a band source slicer “KMK-09-0005-HT” in which the compression ratio of the upper and lower rolls is set to 15% and the height distance between the upper roll and the band saw is set to 0.65 mm. ”(Made by Kitajima Machine Knife Co., Ltd.) and sliced as shown in FIG. 1, and after removing the non-porous film on one side of the 400 mm × 300 mm surface of the porous body, 10%, the height distance between the upper roll and the band saw was set to 0.20 mm, and the surface from which the non-porous film was removed was sliced again with a band source slicer to obtain a silk fibroin porous sheet.

The thickness, size, processability and 25% compression hardness of the silk fibroin porous sheet were evaluated by the following method.
(Slicing availability)
Slicing is performed under the set conditions, and it is possible to obtain a sheet without any problems such as cracking or wrapping. When the sheet is cracked, it is cracked. The case where the fibroin porous material flowed and could not be sliced was defined as a flow.
(Size measurement)
When the size of the silk fibroin porous sheet was measured with a ruler, it was 382 mm × 286 mm, which was equivalent to the size of the silk fibroin porous body before cutting.
(Thickness measurement)
The thickness of the silk fibroin porous sheet was measured with a thickness gauge “547-321” (manufactured by Mitutoyo Corporation) as shown in FIG. 4 to measure the thickness at 12 locations within the sheet, and the average value of the thickness at the 12 locations was determined as silk fibroin. The thickness of the porous sheet was used.
(25% compression hardness)
For the fibroin porous sheet, a universal testing machine “EZ- (N) S” (model number, manufactured by Shimadzu Corporation) was used, the load cell was 50 N, a circular compression plate having a diameter of 8 mm was used as a jig, and the compression speed was 1 mm. / Min, at a room temperature of 22 ° C., the load when 25% of the thickness of the material was pressed with a compression plate was measured, and the value calculated by the following equation was taken as 25% compression hardness (kPa).
25% compression hardness (kPa) = (Load (N) / area of compression plate (mm ² ) when 25% of material thickness is pressed with compression plate)) × 1000
(Electron microscope observation)
6 and 7 show the results of observing the structure of the surface from which the non-porous film before slicing and the non-porous film after slicing have been removed using a scanning electron microscope. Using a scanning electron microscope “XL30-FEG” (manufactured by Philips), measurement was performed in a low vacuum Pt deposition mode and an acceleration voltage of 10 kV. 6 and 7 show that the non-porous film has been removed by slicing.

Examples 2-14
Silk fibroin concentration of the silk fibroin solution poured into the container, additive type, container size, concentration of glycerin solution to be immersed, slicer setting when making porous sheet (compression rate and height distance between upper roll and band saw) A silk fibroin porous sheet was obtained in the same manner as in Example 1 except for changing to the one shown in Table 1.

Corresponding container sizes are as follows (length x width x thickness).
* 1: 400mm x 300mm x 10mm
* 2: 400mm x 300mm x 5mm
* 3: 400mm x 300mm x 20mm
* 4: 150mm x 50mm x 10mm

From Examples 1 to 6 in Table 1, it was found that a silk fibroin porous sheet having an arbitrary thickness can be obtained by changing the compression ratio and the height distance between the upper roll and the band saw.
From Examples 7 to 9 in Table 1, it was found that the silk fibroin porous material can be similarly processed even if the thickness and size of the porous material are different.
From Examples 10 to 14 in Table 1, even if the hydroxyl compound content (the concentration of glycerin immersed in the table and the glycerin mass ratio in the dry porous material), the type of additive, the concentration of fibroin, etc. are changed, the same processing I found it possible.

Example 15
The silk fibroin solution was prepared in the same manner as in Example 1, the silk fibroin porous material was produced, and the hydroxyl group-containing compound was introduced. The resulting dried silk fibroin porous material into which the hydroxyl compound was introduced was compressed into upper and lower rolls. As shown in FIG. 1, using a band source slicer “KMK-09-0005-HT” (manufactured by Kitajima Machine Knife Co., Ltd.) with the height distance between the upper roll and the band saw set to 0.4 mm. After slicing and removing a 400 mm × 300 mm surface non-porous film of the porous body, the surface from which the non-porous film has been removed is further sliced under the conditions shown in Table 2 to obtain a silk fibroin porous sheet Got.

Example 16
Using the remainder of the silk fibroin porous material used in obtaining the silk fibroin porous sheet in Example 15, further slicing was performed on the surface sliced in Example 15 under the conditions shown in Table 2. And a silk fibroin porous sheet was obtained.

Example 17
Using the remaining silk fibroin porous material used in obtaining the silk fibroin porous sheet in Example 16, further slicing was performed on the surface sliced in Example 16 under the conditions shown in Table 2. And a silk fibroin porous sheet was obtained.

Examples 18-23
Using the remaining silk fibroin porous material used in the previous example as in Examples 16 and 17, slicing was performed under the conditions described in Table 2 to obtain a silk fibroin porous sheet. .

Corresponding container sizes are as follows (length x width x thickness).
* 1: 400mm x 300mm x 10mm
From Examples 15 to 23 in Table 2, it was found that a plurality of sheets can be obtained from one block by repeatedly slicing one silk fibroin porous body. Further, it was found that a silk fibroin porous sheet having an arbitrary thickness can be obtained by changing the height distance between the upper roll and the band saw even from a silk fibroin porous body that has been repeatedly sliced.

Example 24, Comparative Examples 1-5
Preparation of a silk fibroin porous sheet was attempted in the same manner as in Example 1 except that the concentration of the glycerin solution to be immersed and the setting of the slicer (the compressibility and the height distance between the upper roll and the band saw) were changed. The results are shown in Table 3.

  It turned out that the slice to thickness thinner than 0.2 mm from the comparative example 1 is difficult. It was found that slicing could not be performed if the compression rate was not set to an appropriate value as compared with Comparative Examples 2 and 3. In Comparative Example 4, the produced silk fibroin porous material was already cracked after drying, and when it was sliced, it was further broken and a sheet could not be obtained. Thus, a hydroxyl group-containing compound (glycerin) It was found that a good porous sheet could not be obtained by slicing when no was added. From Comparative Example 5, it was found that if a large amount of the hydroxyl group-containing compound (glycerin) was added, the porous body was wound around the roll during slicing and could not be sliced.

Comparative Example 6
In Example 1, it replaced with the silk fibroin porous sheet, and produced the sheet | seat using the spunlace cotton nonwoven fabric (weighing 30g / m < ² >, Marusan Sangyo Co., Ltd. product). The sheet thickness was 0.24 mm.

Comparative Example 7
In Example 1, it replaced with the silk fibroin porous sheet and produced the sheet | seat using the spunlace cotton nonwoven fabric (weighing 70g / m < ² >, Marusan Sangyo Co., Ltd. product). The sheet thickness was 0.40 mm.

* 5: Silk fibroin porous material
* 6: Spunlaced cotton non-woven fabric (weighing 30 g / m ² )
* 7: Spunlace cotton nonwoven fabric (weight per unit area: 70 g / m ² )

Table 4 shows the results of evaluating the transparency and adhesion of Examples 1 to 6, Example 24, and Comparative Examples 6 and 7 by the following method.
(Transparency evaluation)
Silk fibroin porous sheets (Examples 1 to 6 and Example 24) completely absorbed on a Japanese skin standard color plate (Bio Skin Plate (Bio Color), manufactured by Beaulux Co., Ltd.) and Comparative Examples 6 and 7 The color difference ΔE * ab (D65) was measured in SCE mode from the porous sheet using a color difference meter “CM-700d” (manufactured by Konica Minolta). The reference color was the Japanese skin standard color plate. The transparency is higher as the color difference compared to the reference color is smaller. Moreover, the color difference per unit thickness was calculated by the following formula, and 10 or less was defined as being transparent.
(Color difference per unit thickness, mm ⁻¹ ) = (Color difference ΔE * ab) / (Thickness, mm)

(Adhesion evaluation)
Regarding the adhesion when the nonwoven fabrics of silk fibroin porous sheets (Examples 1 to 6 and Example 24) and Comparative Examples 6 and 7 were applied to the face by the following usage method, 10 panelists (5 Japanese men and Evaluation was performed by 5 Japanese women) according to the following evaluation criteria, and an average score (rounded off after the decimal point) was obtained.
A silk fibroin porous sheet (Examples 1 to 6 and Example 24) and a nonwoven fabric of Comparative Examples 6 and 7 that were completely absorbed in a room at a room temperature of 23.6 ° C. and a relative humidity of 40% were applied to the face and before operation. After evaluating the adhesiveness of the film, the word “aiueo” was used to evaluate the adhesiveness after changing the expression. The evaluation criteria were as follows.
5 points: Excellent contact feeling, close contact with the unevenness, and expression may be changed.
4 points: Excellent contact feeling, close contact with unevenness, and expression may be changed.
3 points: Excellent contact feeling and close contact along the unevenness, but it is said to change the expression.
2 points: Inferior to the feeling of adhesion, and uneven parts are lifted.
1 point: There is no feeling of adhesion and sticking is difficult.

From Table 4, the silk fibroin porous sheets of Examples 1 to 6 having a thickness of 0.2 to 1 mm are transparent because the color difference and the color difference per unit thickness are small. The color differences per unit thickness were all 10 mm ⁻¹ or less. Moreover, the silk fibroin porous body of Examples 1-6 has a low color difference per unit thickness compared with the cotton nonwoven fabric widely used as a face mask material, and may be transparent if it is the same thickness. I understood. Moreover, it turned out that the silk fibroin porous sheet of Examples 1-6 and the silk fibroin porous sheet of Example 24 are excellent in adhesiveness compared with the nonwoven fabrics of Comparative Examples 6 and 7.

Comparative Example 8
A silk fibroin solution was prepared under the same conditions as in Example 1, and after producing a silk fibroin porous body, a porous body in a wet state without introducing a hydroxyl group-containing compound and lyophilization Example 1 Cutting with a band source slicer was attempted under the same conditions as above, but the water was squeezed and the crushed porous material passed between the blade and the lower roll and could not be processed.

Comparative Example 9
The porous body in a wet state prepared by the same operation as in Comparative Example 8 was cut with a cutter to try to produce a porous sheet. Although cutting was attempted by applying a blade at an interval of 0.25 mm, the porous body was crushed and deformed by the pressure when pressing the cutter, and the porous body escaped from the blade because it was too soft. It was difficult to process into a sheet.

Comparative Example 10
The porous body in a wet state prepared by the same operation as in Comparative Example 8 was cut with a cutter to try to produce a porous sheet. Although cutting was attempted by applying blades at intervals of 1 mm, the porous body was crushed and deformed by the pressure applied when the cutter was pressed, and the porous body escaped from the blades because it was too soft. It was difficult to process.

  From Comparative Example 8 to Comparative Example 10, it was found that it was difficult to process a porous sheet of 1 mm or less using a wet porous body.

Comparative Example 11
The silk fibroin porous material prepared by preparing a silk fibroin solution, producing a silk fibroin porous material, introducing a hydroxyl group-containing compound, and freeze-drying by the same operation as in Example 1 was cut with a cutter, I tried to make it. Although cutting was attempted by applying a blade at an interval of 0.25 mm, the porous body was crushed and deformed by the pressure when pressing the cutter, and the porous body escaped from the blade because it was too soft. It was difficult to process into a sheet.

Comparative Example 12
Preparation of a silk fibroin solution, production of a silk fibroin porous material, introduction of a hydroxyl group-containing compound, and freeze-drying were carried out in the same manner as in Example 1 to cut the produced silk fibroin porous material with a cutter to produce a porous sheet. Tried. As a result of cutting by applying a blade at intervals of 1 mm, it was possible to obtain a silk fibroin porous sheet having a size of about 3 cm × 4 cm and a thickness of about 1 mm, but a sheet having a size larger than that was obtained. It was difficult because the accuracy of the thickness was poor.

  If it is a silk fibroin porous body having an appropriate hardness than Comparative Examples 11 and 12, it can be processed by a simple method such as a cutter, but a silk fibroin porous sheet with a large size and thickness is highly accurate. It turned out to be difficult to obtain.

  Table 5 shows the results of evaluating thickness variations of Example 1, Example 6, and Comparative Example 12 by the following method. The thickness variation was determined by the method described in the specification text. Further, since the silk fibroin porous sheet obtained in Comparative Example 12 had an irregular upper size and 12 points were difficult to measure, 5 points were measured as shown in FIG.

  From Table 5, it was found that the thickness variation of the silk fibroin porous sheet cut with a cutter was large. From this, it was found that a silk fibroin porous sheet having a large area and a small thickness variation can be obtained only by processing a silk fibroin porous material having an appropriate hardness under an appropriate processing technique and appropriate conditions.

Comparative Example 13
The size of the mold made of the aluminum plate was set to 400 mm × 300 mm × 1 mm, and hard filter paper No. A silk fibroin solution was prepared and a silk fibroin porous body was produced in the same manner as in Example 1 except that 4A (manufactured by ADVANTEC) was attached.
As a result, the filter paper affixed to the mold made of an aluminum plate and the silk fibroin porous body were firmly fixed and did not peel off, and only fragments were obtained even when forcibly peeling off.

  When the thickness was thinner than Comparative Example 13, it was found that it was difficult to remove the non-porous coating on the surface using filter paper.

Example 25
A dried silk fibroin porous material was obtained in the same manner as in Example 1 except that the size of the mold made of the aluminum plate was 100 mm × 100 mm × 6.0 mm and the concentration of the glycerol aqueous solution to be immersed was 3% by volume.
The obtained silk fibroin porous body was sliced to obtain a silk fibroin porous sheet having a thickness of 3.0 mm. Using this silk fibroin porous sheet, a water absorption rate test was conducted according to the following method. The results are shown in Table 6.
(Water absorption rate test)
1 mL of ultrapure water was dropped in the vicinity of the center of the 100 mm × 100 mm surface of the porous material using a push-button liquid microvolume meter “Pipetteman P-1000” (manufactured by Gilson). The water absorption rate was calculated according to the following equation. The measurement was performed 5 times, and the average value was obtained.
Water absorption rate (μl / second) = Pure water dripping amount (1000 μl) / Time required for water absorption (second)

Comparative Example 14
A dried silk fibroin porous material was obtained in the same manner as in Example 1 except that the size of the mold made of the aluminum plate was 100 mm × 100 mm × 3.0 mm and the concentration of the glycerin aqueous solution to be immersed was 3% by volume. Using this dried silk fibroin porous material, a water absorption rate test was conducted in the same manner as in Example 25. The results are shown in Table 6.

Comparative Example 15
The dried silk fibroin porous material was the same as in Example 1 except that the size of the mold made of the aluminum plate was set to an inner diameter of 100 mm × 100 mm × 3.0 mm, and the obtained silk fibroin porous material was not immersed in the glycerin aqueous solution. Got the body. Using this dried silk fibroin porous material, a water absorption rate test was conducted in the same manner as in Example 25. The results are shown in Table 6.

  From the results of Example 25 and Comparative Examples 14 and 15, in the wound dressing of the present invention, since the non-porous film present on both surfaces of the fibroin porous body is usually removed by processing, the pores are exposed. It was found that the liquid absorption speed was excellent.

Example 26
A silk fibroin porous sheet was prepared in the same manner as in Example 1, and a water retention test was performed according to the following method.
As a result, the water retention rate was as large as 1710%, and a large amount of leachate could be absorbed, which proved useful as a wound dressing.
(Water retention test)
After weighing the dried silk fibroin porous material (the mass at this time is referred to as “dry mass”), it was immersed in ultrapure water for 30 seconds. Subsequently, it was kept in the air for 30 seconds, the surface moisture was dropped, weighed again (the mass at this time was referred to as “wet mass”), and the water retention rate was calculated according to the following formula.
Water retention rate (%) = (wet mass (g) −dry mass (g)) / dry mass (g)

  The silk fibroin porous sheet of the present invention is used in cosmetics and esthetics for the purpose of moisturizing, etc. for use in esthetic salons or individuals; skin care fields such as face masks and eye masks; wound dressings, drug sustained-release carriers, hemostatic sponges Medical fields such as disposable diapers, sanitary products, daily necessities, water purification and environmental fields that can be used as a support for microorganisms, bacteria, etc .; cell culture supports (scaffolds) in tissue engineering, regenerative medical engineering, etc. It is applicable to various industries such as materials) and tissue regeneration supports.

Claims (16)

  A fibroin porous sheet having a 25% compression hardness of 200 kPa to 800 kPa and a thickness of 0.25 mm to 2.5 mm, wherein at least one surface of the sheet does not have a non-porous coating over the entire surface.   The fibroin porous sheet according to claim 1, wherein the thickness is 0.25 mm to 1 mm.   The fibroin porous sheet according to claim 1 or 2, wherein both surfaces of the sheet do not have a non-porous film over the entire surface.   The fibroin porous sheet according to any one of claims 1 to 3, wherein an area ratio of pores is 60% to 99% on a surface having no non-porous film over the entire surface. Area of the sheet is 15cm ² ~1200cm ^2, fibroin porous sheet according to any one of claims 1-4. The positive thickness variation represented by the following formula (1) and the negative thickness variation represented by the following formula (2) are both within 15%, according to any one of claims 1 to 5: The fibroin porous sheet as described.
Positive thickness variation (%) = {(maximum thickness (mm)) / (average thickness (mm)) × 100} −100 (1)
Negative thickness variation (%) = 100 − {(minimum thickness (mm)) / (average thickness (mm) × 100} (2)   The fibroin porous sheet according to any one of claims 1 to 6, comprising a hydroxyl group-containing compound.   The fibroin porous sheet according to claim 7, wherein the hydroxyl group-containing compound is glycerin.   The fibroin porous sheet according to any one of claims 2 to 8, wherein the color difference is 0.50 to 7.94.   The fibroin porous sheet according to any one of claims 2 to 9, wherein a color difference per unit thickness is 2.1 to 7.8.   The fibroin porous sheet according to any one of claims 1 to 10, wherein the fibroin is silk fibroin.   The medical sheet which uses the fibroin porous sheet of any one of Claims 1-11.   A wound dressing comprising the fibroin porous sheet according to any one of claims 1 to 11.   A method for producing a fibroin porous sheet, comprising compressing a dry fibroin porous material having a 25% compression hardness of 200 kPa to 800 kPa at a compression rate of 7% to 40% and slicing with a band saw.   The manufacturing method of the fibroin porous sheet of Claim 14 with which the said dry fibroin porous body contains 20 mass%-60 mass% of hydroxyl-containing compounds. The method for producing a fibroin porous sheet according to claim 14 or 15, wherein the dried fibroin porous material is a silk fibroin porous material.