JP2021028434A - Method for producing polymer substance molding - Google Patents

Abstract

To provide a method for producing a polymer substance molding capable of forming in a dry process, thereby reducing the amount of waste liquid generated by the production, and having high orientation and high elongation and excellent in toughness.SOLUTION: A method for producing a polymer substance molding comprises an extrusion step of extruding a mixed solution containing a polymer substance, an ionic liquid, and a solvent from a discharge port into a gas phase, a solidification step of obtaining a solidified body containing a polymer substance and an ionic liquid by causing a solvent contained in the mixed solution extruded into the gas phase to vaporize in the gas phase, and a heat stretching step of heating and stretching the solidified body in the gas phase.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a polymer substance molded product, which can be molded by a dry method, thereby reducing the amount of waste liquid generated by the production, and having high orientation and strong elongation, and excellent tasness. ..

Known solvents for molding using proteins as raw materials include trifluoroethanol, tetrahydrofuran, hexafluoroisopropanol (HFIP), trifluoroacetic acid, formic acid, water, and dimethylformamide (for example, Non-Patent Document 1). reference). Among them, hexafluoroisopropanol is used in the process of producing silk artificial fibers because it dissolves refined silk fibroin well and is highly volatile (see, for example, Patent Document 1).

However, the molded product obtained by volatilizing the solvent from the silk fibroin solution or desolving it in a coagulation bath has low flexibility and elongation, poor processability, and it is difficult to improve the strong elongation by stretching. Therefore, the strength and elongation were insufficient.

U.S. Pat. No. 5,252,285

D.B. Khadka, D.T. Haynie, Nanomedicine: Nanotechnology, Biology, and Medicine, 8, 1242-1262 (2012)

The present invention has been made in view of such an actual situation, and an object of the present invention is that it can be molded by a dry method, whereby the amount of waste liquid generated by production can be reduced, and the orientation and strength and elongation are high. An object of the present invention is to provide a method for producing a polymer substance molded product having excellent taskiness.

As a result of diligent research to achieve the above object, the present inventors have taken care of this by using a mixed solution containing a polymer substance, an ionic liquid, and a solvent when producing a polymer substance molded product. The solidified material containing the polymer substance and the ionic liquid obtained by extruding into the phase and vaporizing the solvent in the gas phase has excellent flexibility and elongation, and further, such a polymer substance and We have found that by stretching a solidified body containing an ionic liquid, a polymer substance molded body having high orientation and strong elongation and excellent tasness can be obtained, and have completed the present invention.

That is, the present invention relates to the following matters.
[1] An extrusion step of extruding a mixed solution containing a polymer substance, an ionic liquid, and a solvent from a discharge port into a gas phase.
A solidification step of obtaining a solidified body containing a polymer substance and an ionic liquid by vaporizing the solvent contained in the mixed solution extruded into the gas phase in the gas phase.
A method for producing a polymer substance molded product, which comprises a heat-stretching step of heat-stretching the solidified body in a gas phase.

[2] The method for producing a polymer substance molded product according to [1], further comprising an ionic liquid removing step of removing the ionic liquid contained in the solidified body after stretching by the heat stretching step.
[3] In the ionic liquid removal step, the ionic liquid is removed so that the content of the ionic liquid contained in the solidified body is 1% by weight or less with respect to the entire solidified body after stretching. The method for producing a polymer substance molded product according to [2].
[4] The polymer substance molding according to [2] or [3], wherein the removal of the ionic liquid in the ionic liquid removal step is performed by immersing the solidified body after stretching in a good solvent of the ionic liquid. How to make a body.
[5] The method for producing a polymer substance molded product according to any one of [1] to [4], wherein two or more kinds of polymer substances are used as the polymer substance.

[6] The high according to any one of [1] to [5], wherein a solvent having a boiling point of 300 ° C. or lower and capable of dissolving the polymer substance and the ionic liquid in an amount of 1% by weight or more is used as the solvent. A method for producing a molecular substance molded product.
[7] The method for producing a polymer substance molded product according to any one of [1] to [6], wherein the polymer substance is a protein.
[8] The method for producing a polymer substance molded product according to [7], wherein the protein is a structural protein.
[9] The method for producing a polymer substance molded product according to [7] or [8], wherein the protein is fibroin.
[10] The method for producing a polymer substance molded product according to any one of [7] to [9], wherein the protein is silk fibroin.

[11] The polymer substance molded product according to any one of [1] to [10], wherein the ionic liquid has a melting point of less than 100 ° C., a heating weight reduction rate of 10% by mass, and a temperature of 200 ° C. or higher. Production method.
[12] The method for producing a polymer substance molded product according to any one of [1] to [11], wherein the ionic liquid contains an imidazolium structure-containing cation.
[13] The method for producing a polymer substance molded product according to [12], wherein the imidazolium structure-containing cation is 1-hexyl-3-methylimidazolium cation.
[14] The method for producing a polymer substance molded product according to claim [13], wherein the ionic liquid is 1-hexyl-3-methylimidazolium chloride.
[15] The method for producing a polymer substance molded product according to any one of [1] to [14], wherein the solvent is hexafluoroisopropanol.

[16] The method for producing a polymer substance molded product according to any one of [1] to [15], wherein the stretching ratio in the heating and stretching step is 3 times or more.
[17] In the extrusion step, the mixed solution is continuously extruded into the gas phase from the discharge port.
In the solidification step, the solvent contained in the mixed solution extruded continuously is vaporized in the gas phase to continuously obtain the solidified body.
The polymer substance molded product according to any one of [1] to [16], wherein a fibrous polymer substance molded product is obtained by continuously stretching the solidified product obtained in the heat stretching step. Manufacturing method.

According to the present invention, it is possible to perform dry molding, thereby reducing the amount of waste liquid generated by the production, and producing a polymer substance molded product having high orientation and strong elongation and excellent tasness. A method can be provided.

FIG. 1 is a diagram showing an example of a spinning apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing stress-strain curves of Examples 1 and 2 and Comparative Examples 1 and 2. FIG. 3 (A) is a polarizing microscope photograph of the heat-drawn yarn (without methanol washing) obtained in Example 1, and FIG. 3 (B) is an undrawn yarn (without methanol washing) obtained in Reference Example 1. ) Is a polarizing microscope photograph. FIG. 4 (A) is an electron micrograph of the side surface of the heat-drawn yarn (without methanol washing) obtained in Example 1, and FIG. 4 (B) is a heat-drawn yarn (methanol) obtained in Example 1. It is an electron micrograph of a cross section (without cleaning). FIG. 5 (A) is an electron micrograph of the side surface of the heat-drawn yarn (with methanol washing) obtained in Example 2, and FIG. 5 (B) is a heat-drawn yarn (methanol) obtained in Example 2. It is an electron micrograph of a cross section (with cleaning). FIG. 6 is an X-ray spectrum (EDX spectrum) extracted from a cross section of the heat-drawn yarn (without methanol washing) obtained in Example 1. FIG. 7 (A) is an EDX field image of a cross section of the heat drawn yarn (without methanol washing) obtained in Example 1, and FIG. 7 (B) shows a chlorine signal in the cross section shown in FIG. 7 (A). It is an element mapping image of interest. FIG. 8 is an X-ray spectrum (EDX spectrum) extracted from a cross section of the heat-drawn yarn (with methanol washing) obtained in Example 2. FIG. 9A is an EDX field image of a cross section of the heat drawn yarn (with methanol washing) obtained in Example 2, and FIG. 9B shows a chlorine signal in the cross section shown in FIG. 9A. It is an element mapping image of interest.

The method for producing a polymer substance molded product of the present invention is:
An extrusion process that extrudes a mixed solution containing a polymer substance, an ionic liquid, and a solvent from the discharge port into the gas phase.
A solidification step of obtaining a solidified body containing a polymer substance and an ionic liquid by vaporizing the solvent contained in the mixed solution extruded into the gas phase in the gas phase.
It is provided with a heating and stretching step of heating and stretching the solidified body in the gas phase.

The polymer substance used in the present invention may be a polymer substance, and is not particularly limited, and examples thereof include proteins, polysaccharides, and synthetic polymers. In addition, these polymer substances may be used individually by 1 type, and may be used in combination of 2 or more types.

Examples of proteins include recombinant proteins having a molecular weight of 5000 daltons or more, fusion proteins, recombinant proteins, structural proteins, functional proteins, and artificial structural proteins derived from these proteins. Among these, structural proteins, functional proteins, and artificial structural proteins derived from structural proteins and functional proteins are preferable, and structural proteins are more preferable. The functional protein is a protein having physiological activity, and examples thereof include bovine serum albumin and immunoglobulin, and bovine serum albumin is preferable. The structural protein is a protein that forms or retains its structure and morphology in vivo, and examples of the structural protein include fibroin, keratin, collagen, elastin, resilin, and the like, and among these, orientation. Fibroin is preferred from the viewpoint of obtaining a better molded product due to its properties and strong elongation.

Examples of fibroin include silk fibroin, spider silk fibroin, hornet silk fibroin, and the like, and these may be used in combination. For example, when silk fibroin and spider silk fibroin are used in combination, the ratio of silk fibroin is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably, with respect to 100 parts by mass of spider fibroin. It is 10 parts by mass or less.

The silk fibroin may be sericin-removed silk fibroin, sericin-unremoved silk fibroin, or a combination thereof. Sericin-removed silk fibroin is purified by removing sericin that covers silk fibroin and other fats. The silk fibroin purified in this way is preferably used as a lyophilized powder. Sericin-unremoved silk fibroin is unrefined silk fibroin from which sericin and the like have not been removed.

The spider silk fibroin may contain a spider silk polypeptide selected from the group consisting of a natural spider silk protein and a polypeptide derived from the natural spider silk protein (artificial spider silk protein).

The one derived from the natural spider silk protein has an amino acid sequence similar to or similar to the amino acid repeat sequence of the natural spider silk protein, and is, for example, a mutation of the recombinant spider silk protein or the natural spider silk protein. Examples include bodies, analogs or derivatives. The spider silk protein is preferably a large spider silk thread protein produced in a large bottle-shaped gland of a spider or a spider silk protein derived from the large spider silk thread protein. Examples of the large spider thread protein include large bottle-shaped gland spiders MaSp1 and MaSp2 derived from Nephila clavipes, ADF3 and ADF4 derived from Araneus diadematus.

The spider silk protein may be a small spider silk thread protein produced in a small bottle-shaped gland of a spider or a spider silk protein derived thereto. Examples of the small spit tube bookmark thread protein include vial-shaped gland spidroins MiSp1 and MiSp2 derived from Nephila clavipes.

In addition, the spider silk protein may be a weft protein produced in the flagellar form ground of a spider or a spider silk protein derived thereto. Examples of the weft protein include flagellar silk protein derived from Nephila clavipes in the United States.

The polysaccharide is not particularly limited, and examples thereof include cellulose, hemicellulose, glycogen, starch, chitin, chitosan, agarose, and carrageenan.

The synthetic polymer may be any of a synthetic polymer obtained by a polycondensation reaction, a synthetic polymer obtained by chain polymerization, and other synthetic polymers, and is not particularly limited, but for example, a styrene polymer. , Acrylic polymer, methacrylic polymer, carboxylic acid vinyl ester polymer, poly-N-vinyl compound polymer, polyolefin polymer, polydiene polymer, polyester polymer, silicone polymer, polyurethane Examples thereof include based polymers, polyamide-based polymers, polyimide-based polymers, epoxy-based polymers, polyvinyl butyral-based polymers, phenol-based polymers, amino-based polymers, oxazoline-based polymers, and carbodiimide-based polymers.

The ionic liquid may be an organic salt that is liquid at a temperature lower than 100 ° C., and is not particularly limited. For example, imidazolium, pyrrolidinium, piperidinium, pyridinium, quaternary ammoniwam, quaternary phosphonium, sulfonium, and these. Examples thereof include salts of cations such as derivatives and anions such as halogen, triflate, tetrafluoroborate and hexafluorophosphate. Among these, an imidazolium salt containing an imidazolium structure-containing cation such as an imidazolium cation is preferable from the viewpoint of compatibility with a polymer substance.

Examples of the imidazolium salt include 1,3-dimethylimidazolium salt, 1-ethyl-3-methylimidazolium salt, 1-methyl-3-propylimidazolium salt, 1-butyl-3-methylimidazolium salt, and the like. 1-Hexyl-3-methylimidazolium salt, 1-methyl-3-n-octylimidazolium salt, 1- (2-hydroxyethyl) -3-methylimidazolium salt, 1-decyl-3-methylimidazolium salt , 1-ethyl-2,3-dimethylimidazolium salt, 1,2-dimethyl-3-propylimidazolium salt, 2,3-dimethyl-1-propylimidazolium salt, 1-butyl-2,3-dimethylimidazolium salt, 1-butyl-2,3-dimethylimidazolium salt Rium salt, 1-hexyl-2,3-dimethylimidazolium salt, etc. are mentioned, and among these, 1-ethyl-3-methylimidazolium salt, 1-butyl-3-methylimidazolium salt, 1-hexyl The -3-methylimidazolium salt is preferable, and the 1-hexyl-3-methylimidazolium salt is more preferable.

For example, various cations
[Emim] 1-Ethyl-3-methylimidazolium ion
[Bmim] 1-Butyl-3-methylimidazolium ion
[Hmim] 1-hexyl-3-methylimidazolium ion
[Omim] 1-Methyl-3-octylimidazolium ion
[Dmim] 1-decyl-3-methylimidazolium ion Various anions,
[Cl] Chloride ion
[Ac] Acetate ion
[DMP] Dimethyl phosphate ion
[DEP] diethyl phosphate ion
[TfO] Trifluoromethanesulfonate ion
[TFSI] When bis (trifluoromethanesulfonyl) imide ion is used, the ionic liquids shown below are exemplified.
[Emim] [Cl], [Bmim] [Cl], [Hmim] [Cl], [Omim] [Cl], [Dmim] [Cl]
[Emim] [Ac], [Bmim] [Ac], [Hmim] [Ac], [Omim] [Ac], [Dmim] [Ac]
[Emim] [DMP], [Bmim] [DMP], [Hmim] [DMP], [Omim] [DMP], [Dmim] [DMP]
[Emim] [DEP], [Bmim] [DEP], [Hmim] [DEP], [Omim] [DEP], [Dmim] [DEP]
[Emim] [TfO], [Bmim] [TfO], [Hmim] [TfO], [Omim] [TfO], [Dmim] [TfO]
[Emim] [TFSI], [Bmim] [TFSI], [Hmim] [TFSI], [Omim] [TFSI], [Dmim] [TFSI]
Among these, 1-hexyl-3-methylimidazolium chloride ([Hmim] [Cl]) is preferably used.

The ionic liquid preferably has a melting point of less than 100 ° C. and a heating weight reduction rate of 10% by mass and a temperature of 200 ° C. or higher, a melting point of less than 60 ° C., and a heating weight reduction rate of 10% by mass. It is more preferable that the temperature is 250 ° C. or higher. The heating weight reduction rate is a value calculated from the weight change from the start of heating when the ionic liquid is heated to 50 to 500 ° C. at a quasi-static rate (5 ° C./min). Further, as the ionic liquid, it is preferable to use a liquid in which the polymer substance to be used is dissolved in an amount of 5% by weight or more, and it is more preferable to use a liquid in which the polymer substance to be used is dissolved in an amount of 7% by weight or more.

The solvent is not particularly limited, but is preferably one having a boiling point of 300 ° C. or lower and capable of dissolving 1% by weight or more of a polymer substance and an ionic liquid, and for example, hexafluoroisopropanol and hexafluoroacetone are preferable. , Hexafluoroisopropanol is particularly suitable.

Next, the method for producing the polymer substance molded product of the present invention will be described in detail. In the present invention, the polymer substance molded product can be produced, for example, by using the spinning apparatus according to the embodiment of the present invention shown in FIG. In the following, the description will be focused on the manufacturing method using the spinning device shown in FIG. 1, but the manufacturing method of the polymer substance molded product of the present invention is particularly applied to the manufacturing method using the spinning device shown in FIG. It is not limited.

In the production method of the present invention,
First, a mixed solution containing the above-mentioned polymer substance, ionic liquid, and solvent is extruded into the gas phase from the discharge port (extrusion step).
Next, the solvent contained in the mixed solution extruded into the gas phase is vaporized in the gas phase to obtain a solidified body containing a polymer substance and an ionic liquid (solidification step).
Then, the obtained solidified body is heat-stretched in the gas phase to obtain a polymer substance molded product (heat-stretching step).

The extrusion step and the solidification step in the production method of the present invention can be performed, for example, by using the spinning apparatus shown in FIG. The spinning apparatus shown in FIG. 1 has a storage tank 10, and a mixed solution 20 containing a polymer substance, an ionic liquid, and a solvent is stored in the storage tank 10. Then, according to the spinning apparatus shown in FIG. 1, the mixed solution 20 is continuously extruded into the gas phase from the nozzle 40 having a discharge port at the tip by the gear pump 30 attached to the lower end of the storage tank 10. .. Then, the extruded mixed solution 20 falls toward the winder 60 due to gravity, and the solvent contained in the mixed solution 20 evaporates in the gas phase to become a fibrous solidified body, and the winder 60 becomes a fibrous solidified body. Taken up by. The solidified body wound by the winder 60 contains a polymer substance and an ionic liquid.

Then, the fibrous solidified body wound by the winder 60 is heated and stretched to obtain a polymer substance molded product. The method of stretching is not particularly limited, but uniaxial stretching is preferable.

The method for preparing the mixed solution 20 is not particularly limited, and examples thereof include a method of mixing a polymer substance, an ionic liquid, and a solvent with a mixing device. In this case, from the viewpoint of mixability, a method of first mixing the polymer substance and the solvent and then adding the ionic liquid is preferable.

The content ratio of the polymer substance in the mixed solution 20 is preferably more than 5% by weight, 30% by weight or less, more preferably 7% by weight to 25% by weight, still more preferably 10% by weight to 18% by weight.
The content of the ionic liquid in the mixed solution 20 is preferably more than 0 parts by weight and 100 parts by weight or less, preferably 1 to 50 parts by weight, and more preferably 12 to 12 to 100 parts by weight with respect to 100 parts by weight of the polymer substance. 25 parts by weight.

The nozzle 40 and the discharge port provided at the tip thereof are not particularly limited, and may be appropriately selected according to the shape and size of the polymer substance molded product to be manufactured. For example, the discharge port is a multi-hole discharge port. May be. The inner diameter of the nozzle 40 is preferably 0.1 to 0.6 mm, more preferably 0.15 to 0.3 mm.

Further, in the present embodiment, when the mixed solution 20 is continuously extruded from the nozzle 40, a method of extruding into the gas phase and evaporating the solvent in the gas phase, that is, a dry spinning method is adopted. Is. The gas phase is not particularly limited, and may be in the air, in an inert gas, or in a non-oxidizing atmosphere. Further, when the solvent is evaporated in the gas phase, a method of blowing hot air, a method of heating, or the like may be adopted, if necessary. According to the present embodiment, since the dry spinning method is used, the amount of waste liquid can be reduced as compared with the dry-wet spinning method and the wet spinning method, whereby the environmental load can be reduced, and moreover, the environmental load can be reduced. Since the manufacturing process can be simplified, the production efficiency can be improved.

The distance D from the discharge port of the nozzle 40 to the winder 60 is such that the solvent contained in the mixed solution 20 extruded from the discharge port of the nozzle 40 sufficiently evaporates, whereby the solvent can be sufficiently wound up by the winder 60. The length may be set so that it can be a solidified body, but it is usually about 50 cm to 5 m. Further, in the present embodiment, the solidified body after the solvent has evaporated may be substantially free of the solvent, or if it is about several% by weight, the solvent remains. You may.

In addition, in this embodiment, it is preferable that the mixed solution 20 extruded from the discharge port of the nozzle 40 flows down according to gravity, and by making such a mode, the flow orientation of the polymer substance is changed. It can occur and promote crystal orientation, which can result in the resulting polymeric material molded product having higher orientation and strength elongation.

Next, in the present embodiment, the solidified product thus obtained is heat-stretched. The solidified product obtained in the present embodiment is obtained by a dry spinning method and contains a polymer substance and an ionic liquid. Since the solidified body thus obtained by the dry spinning method is obtained by evaporating the solvent in the gas phase, the ionic liquid is uniformly distributed as a plasticizer inside the polymer substance. Can be done.

Therefore, according to the present embodiment, when the solidified body is heated and stretched, the polymer substance contained in the solidified body can be put into a molten state using an ionic liquid as a plasticizer, and in such a molten state. It enables stretching. In particular, according to the present embodiment, during heat stretching, the action of the ionic liquid can cause relaxation of the polymer chains while preventing microstructural destruction in the solidified body subjected to heat stretching. By stretching in such a state, the molecular orientation of the polymer chain can be effectively enhanced. As a result, it is possible to obtain a polymer substance molded product having high orientation and strong elongation and excellent tasness. Although it is not always clear why the action of the ionic liquid can suppress the microstructural destruction in the solidified body subjected to heating and stretching, the ionic liquid intervenes between the polymer molecular chains to cause the adjacent polymer. It is considered that this is because the relaxation of the polymer molecular chains can be caused while appropriately maintaining the interaction between the molecular chains.

The heating temperature at the time of heating and stretching is not particularly limited, but is preferably a temperature equal to or higher than the glass transition temperature (Tg) of the polymer substance and ionic liquid used, preferably 40 ° C. or higher, and more preferably 100. ° C. or higher, more preferably 120 ° C. or higher. The upper limit of the heating temperature is not particularly limited, but is usually 160 ° C. or lower. Further, the stretching ratio at the time of heat stretching is preferably 3 times or more, more preferably 3.5 times or more, and the upper limit thereof is usually 10 times or less. The heating and stretching method is not particularly limited, but for example, another method is applied to the fibrous solidified body wound by the winder 60 (unwinding side) while applying tension in the longitudinal direction under heating. The fibrous solidified body can be stretched by winding it on a winder (winding side), and the draw ratio at this time can be controlled and calculated according to, for example, the following formula.
Stretching ratio = winding speed ÷ unwinding speed

In this way, according to the present embodiment, a fibrous polymer substance molded product can be obtained. According to the present embodiment, it is possible to perform dry molding, thereby reducing the amount of waste liquid generated by production, and further, it is possible to perform good stretching under heating. The fibrous polymer substance molded product can be made to have high orientation and strong elongation and excellent tasness.

In the present embodiment, the polymer substance molded product (solidified product after stretching) thus obtained may be subjected to a treatment for removing the ionic liquid, if necessary. If the ionic liquid remains, exudation of the ionic liquid may become a problem depending on the use of the obtained polymer substance molded body (solidified body after stretching). In such a case, It is preferable to perform a treatment for removing the ionic liquid. The method for removing the ionic liquid is not particularly limited, and examples thereof include a method in which a polymer substance molded product (solidified product after stretching) is immersed in a good solvent of the ionic liquid for cleaning. The good solvent for the ionic liquid used in this case is not particularly limited and may be appropriately selected depending on the type of the ionic liquid to be used. For example, a polar solvent such as water, methanol or ethanol, acetone, methyl ethyl ketone or the like may be used. Examples include ketone solvents, alcan organic solvents such as n-hexane and n-heptane, ether solvents such as diethyl ether, tetrahydrofuran and cyclopentyl methyl ether, and aproton solvents such as dimethyl sulfoxide and N-methyl-2-pyrrolidone. Be done.

Further, when removing the ionic liquid, the amount of the ionic liquid remaining in the polymer substance molded body (solidified body after stretching) is preferably 1% by weight or less, more preferably 0.1% by weight or less. Therefore, it is desirable to carry out a treatment for removing the ionic liquid. The method for setting the amount of the remaining ionic liquid after the removal of the ionic liquid in the above range is not particularly limited, but the method for adjusting the immersion time in a good solvent or the method for immersing in a good solvent is 30. Examples thereof include a method of heating to about 100 ° C. In addition, a method of irradiating ultrasonic waves to promote the elution of the ionic liquid and a method of stirring a good solvent during immersion can be mentioned. Further, after performing the operation of removing the ionic liquid, it is preferable to dry it if necessary.

In the above, the case of producing a fibrous polymer substance molded product by using the spinning apparatus shown in FIG. 1 has been illustrated and described, but the present invention is not particularly limited to such an embodiment. Absent. For example, in the above-mentioned method, an embodiment in which the solidified body obtained by evaporating the solvent is wound by the winder 60 and then heat-stretched is illustrated, but the solidified material is not wound by the winder 60 and is heated as it is. It may be stretched. Further, the shape of the discharge port when the mixed solution 20 is extruded from the discharge port provided at the tip of the nozzle 40 is not particularly limited, and is a thread-shaped molded body, a string-shaped molded body, a film-shaped molded body, or a tape. It can be shaped according to various shaped bodies such as a shaped body and a hollow thread-shaped molded body.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
(1) Polishing of raw silk 6.5 g of raw silk derived from silk moth is heated with 650 mL of a desericin solution (0.25 w / v% Marcel soap, 0.25 w / v% sodium carbonate aqueous solution) at 85 ° C. for 20 minutes. Was washed with. The supernatant was discarded, and the same operation was repeated twice additionally (a total of three washing operations). After discarding the supernatant, the obtained fibers were rinsed with a sufficient amount of ultrapure water (80 ° C.) and vacuum dried at room temperature (25 ° C.) overnight.
To 4.9 g of vacuum-dried silk, 32.9 g of a mixed solution of calcium chloride / water / ethanol (1/8/2, mol / mol / mol) is added little by little, and heated at 55 ° C. for 1 hour to dissolve. , A silk solution was obtained. The obtained silk solution was returned to room temperature, packed in a cellulose dialysis tube (MWCO: 14000 Da), and replaced with ultrapure water (4 days, 4 ° C.). Then, the silk aqueous solution obtained by dialysis was diluted with ultrapure water so that the silk concentration was 4 wt% or less, and freeze-dried by a conventional method to obtain refined silk.

(2) Preparation of spinning solution (mixed solution) 16.25 g of hexafluoroisopropanol was added to 3.0 g of refined silk, heated to 50 ° C., and mixed to dissolve the refined silk in hexafluoroisopropanol. .. Then, while maintaining the temperature of the obtained solution at 50 ° C., 0.75 g of 1-hexyl-3-methylimidazolium chloride ([Hmim] [Cl]) was added and mixed to spin the product. A liquid (mixed solution) was obtained.

(3) Dry spinning using a spinning solution A stainless steel cylinder (manufactured by Musashi Engineering Co., Ltd.) equipped with a disposable needle with an inner diameter of 0.3 mm is filled with the spinning solution prepared above and pressurized with nitrogen to make the spinning solution. Was continuously discharged into the air. At this time, a needle to which a fluorine-based mold release agent was previously applied was used as the needle of the discharge port, and the discharge direction of the spinning liquid was set to the vertical downward direction. As a specific operation, first, at the start, the spinning liquid is discharged at a nitrogen pressure of 0.3 MPa, the dropped yarn is wound around a roller directly under the cylinder, the discharge is stabilized, and then the pressure is 0.02 MPa. The discharge operation was continuously performed. In line with this, the roller winding speed directly under the cylinder was reduced from the initial speed of 12.0 m / min to 4.0 m / min. In this operation, the spinning liquid discharged from the needle changes from liquid to filamentous by evaporating hexafluoroisopropanol as a solvent in the air, and is continuously wound around the roller in a filamentous state. It became a form to be taken. Then, after winding between the rollers five times, the yarn was guided to a winder (4.2 m / min) equipped with a bobbin, which was used as the raw yarn before drawing. The obtained raw yarn before drawing was vacuum dried together with the bobbin at room temperature (25 ° C.) (drying time: 5 hours).

(4) Thermal drawing of raw yarn Using two winding machines, a device system for winding the raw yarn before drawing obtained above from one and winding the drawn yarn on the other is assembled, and a thermal drawing operation is performed. To obtain a heat-drawn yarn. At this time, a hot plate is placed between the two winders to adjust the temperature to 120 ° C., the speed on the unwinding side is 0.25 m / min, and the speed on the winding side is 0. It was set to 88 m / min. That is, the draw ratio was 3.5 times (= 0.88 m / min ÷ 0.25 m / min).

<Example 2>
A heat-drawn yarn was obtained in the same manner as in Example 1. Then, the obtained heat-drawn yarn was immersed in a sufficient amount of methanol at room temperature (25 ° C.) for 5 minutes, and then vacuum-dried at room temperature (25 ° C.) for 30 minutes to obtain 1-hexyl-3-methylimidazolium. By removing the chloride ([Hmim] [Cl]), a heat-drawn yarn (with methanol washing) was obtained.

<Reference example 1>
An undrawn yarn was obtained in the same manner as in Example 1. In Reference Example 1, heat stretching was not performed.

<Reference example 2>
An undrawn yarn was obtained in the same manner as in Example 1. Then, the unstretched raw yarn is immersed in a sufficient amount of methanol at room temperature (25 ° C.) for 5 minutes, and then vacuum dried at room temperature (25 ° C.) for 30 minutes to produce 1-hexyl-3-methylimidazolium chloride. By removing ([Hmim] [Cl]), undrawn yarn (with methanol washing) was obtained.

<Comparative example 1>
Example 1 except that the refined silk obtained in the same manner as in Example 1 was used, but 1-hexyl-3-methylimidazolium chloride ([Hmim] [Cl]) as an ionic liquid was not blended. In the same manner as above, a spinning solution (mixed solution) was obtained, and dry spinning was carried out in the same manner to obtain raw silk. When the raw yarn obtained in Comparative Example 1 was thermally stretched by the same method as in Example 1, the raw yarn was severely broken and could not be thermally stretched.

<Tensile test>
The heat-drawn yarns obtained in Examples 1 and 2 and the undrawn yarns obtained in Reference Examples 1 and 2 were used, and these were fixed to a test piece paper having a distance between gripping tools of 20 mm with an adhesive. Then, the stress and elongation were measured at a tensile speed of 10 mm / min with an Instron tensile tester INSTRON5943. At this time, the temperature was maintained between 22 and 27 ° C. and the relative humidity between 26 and 46%. The load cell has a capacity of 500 N, and the gripper is a clip type.

The stress-strain curve obtained as a result of the tensile test is shown in FIG.
From FIG. 2, the Young's modulus of Example 2 (with heat stretching and methanol washing) was 4.83 GPa, and the Young's modulus of Example 1 (without heat stretching and methanol washing) was 5.12 GPa, which were similar to each other. .. At the yield point, Example 2 (with thermal stretching and methanol cleaning) had a stress of 108 MPa and a strain of 2.2%, and Example 1 (without thermal stretching and methanol cleaning) had a stress of 160 MPa and a strain of 3.6%. Met.
The physical properties of the breaking point were about the same as in Example 2 (with thermal stretching and methanol cleaning), stress 167 MPa and strain 35%, and in Example 1 (without thermal stretching and methanol cleaning), stress 170 MPa and strain 30%. there were. The tensile stresses of Example 2 (with thermal stretching and methanol cleaning) and Example 1 (without thermal stretching and methanol cleaning) increased monotonically in the section of strain 5 to 30%, and were accompanied by tension during the test. It can be determined that orientation hardening has occurred.

On the other hand, Reference Example 2 (unstretched, with methanol washing) has a Young's modulus of 4.41 GPa, which is the same as Example 2 (with heat stretching and methanol washing) and Example 1 (without heat stretching and methanol washing). Although it was about the same, it broke in the elastic range with a breaking stress of 62 MPa and a breaking strain of 1.8%.

On the other hand, in Reference Example 1 (unstretched, without methanol cleaning), the tensile stress does not exceed 11 MPa at the maximum, and the fracture strain is 221%, that is, the fracture is extended to 2.2 times the initial length and fractures. It showed clearly different physical properties.

The results of Reference Example 2 (unstretched, with methanol washing) and Reference Example 1 (unstretched, without methanol washing) can be said to support that the ionic liquid functions as a plasticizer for protein fibers. That is, Reference Example 1 (unstretched, without methanol cleaning) is an example in which the effect of the plasticizer can be clearly seen, and the presence of the ionic liquid itself does not contribute to the improvement of strength, but greatly contributes to the improvement of elongation. I understand. On the contrary, in Reference Example 2 (unstretched, with methanol washing) in which the ionic liquid was removed by methanol washing, the plasticity was not exhibited and the ionic liquid was broken in the elastic region.

Furthermore, the results of Example 2 (with heat stretching and methanol washing) and Example 1 (without heat stretching and methanol washing) have comprehensive physical properties as compared with unstretched due to the heat heating and stretching step in the presence of an ionic liquid. It suggests that it will improve. Regarding this, it was thought that the relaxation of the protein molecular chain occurred in the process of thermal drawing, and the molecular orientation was enhanced while preventing the structural destruction in the fiber. Along with this, it is considered that the elongation could be maintained even after the ionic liquid was removed by washing with methanol.

Further, in both Example 2 (with thermal stretching and methanol cleaning) and Example 1 (without thermal stretching and methanol cleaning), the breaking strain exceeds 30%, which is higher than the breaking strain of natural silk (about 20%). It was a big one.

<Calculation of toughness>
The toughness of the heat-drawn yarns obtained in Examples 1 and 2 and the undrawn yarns obtained in Reference Examples 1 and 2 was calculated according to the following formula.
In the above formula, W: toughness (MJ / m ³ ), σ: tensile stress: MPa, x: tensile strain (mm / mm).
The toughness value of Example 1 (with heat stretching and methanol washing) was 43.2 MJ / m ³ , and the toughness value of Example 2 (with hot stretching and methanol washing) was 39.4 MJ / m ³ . Yes, the toughness value of Reference Example 1 (unstretched, without methanol cleaning) is 10.2 MJ / m ³ , and the toughness value of Reference Example 2 (unstretched, without methanol cleaning) is 0.7 MJ / m. It was ^3.

<Observation of polarized light with a polarizing microscope>
The heat-drawn yarn obtained in Example 1 (without washing with methanol) and the undrawn yarn obtained in Reference Example 1 (without washing with methanol) were fixed to a slide glass, and polarized light manufactured by Olympus equipped with a polarizer and an analyzer. Observation was performed using a microscope Olympus CX31 with a field image of 10 times the eyepiece and 20 times the objective lens (total 200 times) with the background in a dark state (cross Nicol). FIG. 3 (A) is a polarizing microscope photograph of the heat-drawn yarn (without methanol washing) obtained in Example 1, and FIG. 3 (B) is an undrawn yarn (without methanol washing) obtained in Reference Example 1. ) Is a polarizing microscope photograph. In each case, it can be confirmed that light is transmitted only to the fiber portion and shows an interference color. From this, it can be understood that the crystal orientation of silk fibroin has already occurred in the winding process of the undrawn yarn by the dry spinning. In the dry spinning method of this method, the discharged spinning liquid flows down due to gravity, and it is considered that the protein polymer is fluidly oriented here to generate polarized light.

<Morphological observation with scanning electron microscope (SEM)>
The heat-drawn yarn (without methanol cleaning) obtained in Example 1 was cut with a carbon steel razor and imaged with a scanning electron microscope JSM-7100F manufactured by JEOL Ltd. FIG. 4 (A) is an electron micrograph of the side surface of the heat-drawn yarn (without methanol washing) obtained in Example 1, and FIG. 4 (B) is a heat-drawn yarn (methanol) obtained in Example 1. It is an electron micrograph of a cross section (without cleaning). From FIG. 4 (A), it can be understood that the side surface of the fiber is smooth, and from FIG. 4 (B), the inside of the fiber is densely packed to have a uniform structure.

Similarly, the heat-drawn yarn (with methanol washing) obtained in Example 2 was cut with a carbon steel razor and imaged with a scanning electron microscope JSM-7100F manufactured by JEOL Ltd. FIG. 5 (A) is an electron micrograph of the side surface of the heat-drawn yarn (with methanol washing) obtained in Example 2, and FIG. 5 (B) is a heat-drawn yarn (methanol) obtained in Example 2. It is an electron micrograph of a cross section (with cleaning). From FIGS. 5 (A) and 5 (B), the state of the side surface and the cross section is almost the same as that of the heat-drawn yarn obtained in Example 1 (without methanol washing), and the shape of the fiber surface is affected by the methanol treatment. It can be confirmed that there is no.

<Analysis of ionic liquid contained in heat drawn yarn>
The heat-drawn yarn (without methanol cleaning) obtained in Example 1 was cut with a carbon steel razor, and elemental analysis was performed with an EDX device attached to a scanning electron microscope JSM-7100F manufactured by JEOL Ltd. FIG. 6 is an X-ray spectrum (EDX spectrum) extracted from a cross section of the heat-drawn yarn (without methanol washing) obtained in Example 1. In FIG. 6, the vertical axis represents the intensity (Counts) of the EDX detector, and the horizontal axis represents the energy (keV) of the characteristic X-ray. A chlorine-derived Kα ray was found near 2.6 keV in this spectrum, which was found in the chlorine atom of the ionic liquid (1-hexyl-3-methylimidazolium chloride ([Hmim] [Cl])) used in the examples. It can be understood that it is a characteristic X-ray derived from it. The ionic liquid is generally refractory, and it is clear that almost all of the ionic liquid in the spinning liquid remains in the molded body by dry spinning.

<Distribution of ionic liquid contained in heat drawn yarn>
The heat-drawn yarn (without washing with methanol) obtained in Example 1 was cut with a carbon steel razor, and the chlorine atom (Kα ray: 2.6 keV) was removed by the EDX device attached to the scanning electron microscope JSM-7100F manufactured by JEOL Ltd. Element mapping was performed. FIG. 7 (A) is an EDX field image of a cross section of the heat drawn yarn (without methanol washing) obtained in Example 1, and FIG. 7 (B) shows a chlorine signal in the cross section shown in FIG. 7 (A). It is an element mapping image of interest. From the element mapping image, the chlorine atoms of the ionic liquid (1-hexyl-3-methylimidazolium chloride ([Hmim] [Cl])) are uniformly distributed inside the fiber, that is, the ionic liquid is inside the fiber. It can be understood that it is evenly distributed.

<Confirmation of removal of ionic liquid by washing with methanol>
The heat-drawn yarn obtained in Example 2 (with methanol washing) was attached to the JEOL scanning electron microscope JSM-7100F by the same method as the heat-drawn yarn obtained in Example 1 (without methanol washing). By measuring with an EDX device, it was confirmed that the ionic liquid was removed by washing with methanol. FIG. 8 is an X-ray spectrum (EDX spectrum) extracted from a cross section of the heat-stretched yarn (with methanol washing) obtained in Example 2, and FIG. 9 (A) is the heat-stretching obtained in Example 2. It is an EDX field view image of the cross section of a thread (with methanol washing), and FIG. 9B is an element mapping image focusing on a chlorine signal in the cross section shown in FIG. 9A. As shown in FIG. 8, a peak of chlorine-derived Kα rays could not be confirmed in the vicinity of 2.6 keV, and as shown in FIGS. 9 (A) and 9 (B), the element mapping image of the cross section also showed. No chlorine signal was confirmed. From this result, it can be judged that almost the entire amount (0.1% by weight or less) of the ionic liquid (1-hexyl-3-methylimidazolium chloride ([Hmim] [Cl])) was removed from the fiber by the step of washing with methanol. ..

Claims (17)

An extrusion process that extrudes a mixed solution containing a polymer substance, an ionic liquid, and a solvent from the discharge port into the gas phase.
A solidification step of obtaining a solidified body containing a polymer substance and an ionic liquid by vaporizing the solvent contained in the mixed solution extruded into the gas phase in the gas phase.
A method for producing a polymer substance molded product, which comprises a heat-stretching step of heat-stretching the solidified body in a gas phase. The method for producing a polymer substance molded product according to claim 1, further comprising an ionic liquid removing step of removing the ionic liquid contained in the solidified body after stretching by the heat stretching step. 2. Claim 2 in the ionic liquid removing step, removing the ionic liquid so that the content of the ionic liquid contained in the solidified body is 1% by weight or less with respect to the entire solidified body after stretching. The method for producing a polymer substance molded product according to. The method for producing a polymer substance molded product according to claim 2 or 3, wherein the removal of the ionic liquid in the ionic liquid removal step is performed by immersing the solidified product after stretching in a good solvent of the ionic liquid. The method for producing a polymer substance molded product according to any one of claims 1 to 4, wherein two or more kinds of polymer substances are used as the polymer substance. The polymer substance molded product according to any one of claims 1 to 5, wherein as the solvent, a solvent having a boiling point of 300 ° C. or lower and capable of dissolving the polymer substance and the ionic liquid in an amount of 1% by weight or more is used. Production method. The method for producing a polymer substance molded product according to any one of claims 1 to 6, wherein the polymer substance is a protein. The method for producing a polymer substance molded product according to claim 7, wherein the protein is a structural protein. The method for producing a polymer substance molded product according to claim 7 or 8, wherein the protein is fibroin. The method for producing a polymer substance molded product according to any one of claims 7 to 9, wherein the protein is silk fibroin. The method for producing a polymer substance molded product according to any one of claims 1 to 10, wherein the ionic liquid has a melting point of less than 100 ° C., a heating weight reduction rate of 10% by mass, and a temperature of 200 ° C. or higher. The method for producing a polymer substance molded product according to any one of claims 1 to 11, wherein the ionic liquid contains an imidazolium structure-containing cation. The method for producing a polymer substance molded product according to claim 12, wherein the imidazolium structure-containing cation is 1-hexyl-3-methylimidazolium cation. The method for producing a polymer substance molded product according to claim 13, wherein the ionic liquid is 1-hexyl-3-methylimidazolium chloride. The method for producing a polymer substance molded product according to any one of claims 1 to 14, wherein the solvent is hexafluoroisopropanol. The method for producing a polymer substance molded product according to any one of claims 1 to 15, wherein the stretching ratio in the heat stretching step is 3 times or more. In the extrusion step, the mixed solution is continuously extruded from the discharge port into the gas phase.
In the solidification step, the solvent contained in the mixed solution extruded continuously is vaporized in the gas phase to continuously obtain the solidified body.
The method for producing a polymer substance molded product according to any one of claims 1 to 16, wherein a fibrous molded product is obtained by continuously stretching the solidified product obtained in the heat stretching step.