JP2017197730A - Method for producing molding and molding - Google Patents

Abstract

Provided is a method for producing a molded body, which can produce a molded body derived from biomass having a high flexural modulus without using an additive material such as phenol resin fiber.
A method for producing a molded body, wherein a molded body is obtained by pressurizing and heating a material containing hornet silk in a mold.
[Selection figure] None

Description

  The present invention relates to a method for producing a molded body and a molded body.

  In recent years, there has been an increase in the movement of replacing metal materials with resin materials for the purpose of reducing weight or ensuring ease of molding. As such a resin material, a phenol resin or the like is often used.

For example, Patent Document 1 discloses a phenol resin composition having “phenol resin fiber (A) and matrix resin (B), wherein the matrix resin (B) contains a phenol resin. “A molded product obtained by molding” a “phenol resin composition” (Claim 1) (Claim 7).
The molded body disclosed in Patent Document 1 has acquired characteristics such as a high flexural modulus by adding phenol resin fibers to a matrix resin.

JP 2014-80491 A

In recent years, due to increasing awareness of environmental conservation, bioplastics made from biological resources (biomass) have been attracting attention as deoiling materials.
The inventor paid attention to silk (a protein produced by moth larvae) as biomass, and produced a molded body from silk powder without adding an additive material such as phenol resin fiber. However, the obtained molded body may have insufficient bending elastic modulus.

  Then, an object of this invention is to provide the manufacturing method of a molded object which can manufacture the molded object derived from the biomass which has a high bending elastic modulus, without using additive materials, such as a phenol resin fiber.

  As a result of intensive studies to achieve the above object, the present inventor has found that a molded article having a high flexural modulus can be obtained by using hornet silk, and has completed the present invention.

That is, the present invention provides the following [1] to [8].
[1] A method for producing a molded body, wherein a molded body is obtained by pressurizing and heating a material containing hornet silk in a molding die.
[2] The molded body according to [1], wherein the material containing the hornet silk is a material obtained by removing impurities including wood chips constituting the nest from a cocoon collected from a hornet nest. Production method.
[3] The method for producing a molded article according to the above [1] or [2], wherein a state of the material containing the hornet silk is powder.
[4] The method for producing a molded body according to any one of the above [3], wherein a particle size of the material containing the hornet silk is 400 μm or less.
[5] The method for producing a molded article according to any one of the above [3], wherein a particle size of the material including the hornet silk is less than 150 μm.
[6] The method for producing a molded article according to any one of [3] to [5], wherein a difference between an upper limit value and a lower limit value of a particle size of the material including the hornet silk is 70 μm or less.
[7] The method for producing a molded body according to any one of [1] to [6], wherein the temperature at the time of heating is 100 ° C. or higher.
[8] A molded body obtained by molding a material containing hornet silk, and having a flexural modulus of 5.0 GPa or more.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a molded object which can manufacture the biomass-derived molded object which has a high bending elastic modulus can be provided, without using additive materials, such as a phenol resin fiber.

<Method for producing molded body>
The method for producing a molded body of the present invention (hereinafter, also simply referred to as “the manufacturing method of the present invention”) is a molding in which a molded body is obtained by pressurizing and heating a material containing hornet silk in a mold. It is a manufacturing method of a body.
Hornet silk is biomass like conventional silk, but forms a super-secondary structure different from conventional silk, as will be described later. For this reason, it is speculated that the molded product obtained by the production method of the present invention is superior in properties such as flexural modulus compared to a molded product obtained using conventional silk without adding phenol resin fibers or the like. Is done.

<Hornet Silk>
Hornets make nests by mixing wood chips and dead plants with saliva. The hornet's nest usually has a multi-stage nest that is covered with a ball-shaped outer skin. In each nest, hexagonal nests where hornets of hornets grow are arranged without gaps. The hornet larvae spun from the inside of the nest before making it into a cocoon, creating a cap-shaped cocoon made of hornet silk and blocking the nest entrance.
That is, hornet silk is a protein produced by wasp larvae.
It should be noted that the wings collected from the hornet's nest are usually contaminated with wood chips and the waxes secreted by the hornet larvae from the body surface. It is preferable to use it after that.

  Further, in the present invention, hornet silk is not limited to those constituting cocoons collected from hornets' nests, but is obtained by using a gene recombination technique, for example, a gene encoding hornet silk into E. coli. The produced protein is also included in the hornet silk in the present invention.

That is, the hornet silk in the present invention is a concept including not only a protein itself produced by hornet larvae but also a protein having the same amino acid composition as a protein produced by hornet larvae.
Specifically, the amino acid composition of hornet silk is characterized in that the total of alanine and serine is as high as 50 mol% or more and glycine is as low as 10 mol% or less.
The amino acid composition of such hornet silk is different from that of silk fibroin, which is a protein produced by moth larvae. For example, in the case of rabbits, the total of alanine and serine is only about 45 mol%, and glycine is also high at about 42 mol%. In the case of savages, the total of alanine and serine is relatively high at about 49 mol%, but glycine is also high at about 31 mol%.

  While ordinary silk (silk fibroin) forms a β-sheet structure, which is a planar structure, Hornet silk has a super-secondary coiled-coil structure (the molecular chains of α helices create a left-handed coil). A spiral aggregate formed by intertwining them). It is presumed that the characteristics of the obtained molded body are different depending on the difference in structure.

<Materials including Hornet Silk>
(Outline of materials including Hornet Silk)
The material containing hornet silk used in the present invention (hereinafter also referred to as “HS-containing HS material” for convenience) is not particularly limited as long as it contains hornet silk, but there are also components other than hornet silk in the HS-containing material. It is preferably a biological resource (biomass).
Examples of the HS-containing material include a material that is left without removing impurities from wasps 'wrinkles; a material that is obtained by removing impurities from wasps'wrinkles; and the like.
The state of such an HS-containing material is not particularly limited, but is substantially a powder. Hereinafter, a powdery HS-containing material will be described as an example. However, it is not excluded to use the powdered HS-containing material dissolved or dispersed in a liquid in the process of obtaining a molded body.

(First embodiment of HS-containing material)
Examples of the HS-containing material include a powder obtained by cutting and crushing a cocoon collected from a nest. For example, a ball mill or a jet mill is used for the pulverization. The obtained powder includes not only hornet silk but also impurities.
In addition, after cutting and before pulverization, impurities may be removed by hand sorting as necessary.
Further, impurities may be further separated and removed from the powder obtained by pulverization. At this time, for example, an electrostatic sorting method in which an object is charged using static electricity and sorting and separation using a difference in charge amount can be used.

(Second aspect of HS-containing material)
Hornet silk dissolves efficiently in halogenated organic solvents and neutral salt solutions.
On the other hand, impurities (wood chips, wax, etc.) adhering to the cocoon collected from the hornet's nest are insoluble in the halogenated organic solvent and the neutral salt aqueous solution.
Therefore, the cocoon collected from the hornet's nest is immersed in a halogenated organic solvent or an aqueous neutral salt solution, stirred as necessary to dissolve only the hornet silk, and then passed through a filter or a centrifuge. As a result, impurities that are insoluble components can be separated.

  Examples of the halogenated organic solvent include dichloroacetic acid, trifluoroacetic acid, hexafluoroisopropanol, hexafluoroacetone and the like. Examples of the neutral salt aqueous solution include aqueous solutions of lithium bromide, calcium chloride, copper ethylenediamine, sodium thiocyanate, lithium thiocyanate, magnesium nitrate, and the like.

  In addition, since there exists a solvent which may decompose | disassemble protein in a halogenated organic solvent, it is preferable to cool to 4 degrees C or less in that case, and to prevent decomposition | disassembly. Decomposition hardly occurs below 4 ° C. If the temperature is further reduced, the dissolution rate decreases.

  Hornet silk dissolved in the halogenated organic solvent can be insolubilized and recovered by adding a precipitant that reduces the solubility of the protein. Examples of the precipitating agent include methanol, ether, ethanol and the like.

Hornet silk dissolved in a neutral salt aqueous solution can remove neutral salt components by dialysis using a dialysis membrane. Specifically, for example, in the case of a lithium bromide (LiBr) aqueous solution, lithium bromide can be removed using a dialysis tube made of cellulose.
In the dialysis tube, most of the hornet silk precipitates (solidifies) during the dialysis process, but some of it may dissolve. In that case, solidified hornet silk and dissolved hornet silk can be recovered by filtering or centrifuging the contents of the dialysis tube after dialysis.

  When either a halogenated organic solvent or a neutral salt aqueous solution is used, the recovered hornet silk is dried (for example, freeze-dried) and pulverized to be pulverized. For example, a ball mill or a jet mill is used for the pulverization.

(Particle size of HS-containing material)
Whether it is the first aspect or the second aspect (other aspects), the powdered HS-containing material is appropriately classified before being used as the material of the molded body. May be. Classification is performed, for example, by sieving using an electromagnetic sieve shaker.
The particle size of the powder used after classification is, for example, a particle size having a width such as “106 μm or more and less than 150 μm”.

In the obtained molded body, the above particle size (upper limit value) is preferably smaller because the properties such as bending fracture stress, bending fracture strain, and toughness are excellent. Specifically, the particle size (upper limit) is preferably 400 μm or less, more preferably less than 150 μm, and still more preferably less than 75 μm. In addition, the measuring method (evaluation method) of the bending fracture stress, bending fracture strain, and toughness in this invention is mentioned later.
The molded body obtained using the HS-containing material having a small particle size has a relatively strong interaction between the HS-containing materials constituting the molded body, as compared with the case where the particle size is large, or It becomes high and it becomes difficult to make a crack, so it is estimated that the above characteristics can be obtained.
On the other hand, the lower limit of the particle size is not particularly limited, but is, for example, 5 μm or more.

Moreover, from the reason that the bending elastic modulus of the obtained molded body is more excellent, the difference between the upper limit value and the lower limit value of the particle size is preferably 120 μm, more preferably 70 μm or less.
For example, when the particle size of the powder used after classification is “106 μm or more and less than 150 μm”, the “difference between the upper limit value and the lower limit value” of this particle size is less than 44 μm.
Since the “difference between the upper limit value and the lower limit value” of the particle size of the HS-containing material constituting the molded body is small, the HS-containing material is uniformly dispersed in the molded body. .

<Manufacture of molded body>
The production method of the present invention produces a molded body by pressurizing and heating the above-described HS-containing material in a mold.
The mold used is, for example, a graphite or steel mold, and is appropriately selected according to the desired shape of the molded body. Moreover, in this invention, a rolling roll shall also be contained in a shaping | molding die.
The temperature at the time of heating is preferably 100 ° C. or higher. Although an upper limit is not specifically limited, For example, it is 200 degrees C or less.

  As such a production method of the present invention, for example, a method of hot-pressing a powdery HS-containing material can be mentioned. For hot pressing, it is preferable to use a hot press or a pulse current sintering apparatus. In addition, as a hot press and a pulse electric current sintering apparatus, a conventionally well-known apparatus can be used suitably.

(Hot press forming using hot press)
In the case of hot pressing using a hot press, for example, a powdery HS-containing material or a mixture prepared by adding some water to a powdered HS-containing material is filled in a mold, Is used to obtain a molded body by hot pressing in the atmosphere. Even when the powdery HS-containing material is used as it is, it is considered that the powdery HS-containing material contains some moisture.
The pressure at the time of pressurization is 10-30 MPa, for example. The ultimate temperature is preferably 100 ° C. or higher, more preferably 130 ° C. or higher. Although an upper limit is not specifically limited, For example, it is 200 degrees C or less. Although it depends on the heating time, carbonization of the surface and the like becomes remarkable when the temperature is extremely high.
As other conditions, the heating time is, for example, 150 to 600 seconds, and the pressing time is, for example, 150 to 600 seconds.

(Hot-pressure molding using pulse current sintering equipment)
In the case of hot pressing using a pulse current sintering apparatus, for example, first, a mixture is prepared by adding water such as distilled water to a powdered HS-containing material and mixing uniformly. At this time, the addition amount of water in the mixture is preferably 30% by mass or less, and more preferably 5 to 15% by mass with respect to 100% by mass of the mixture.
Next, the prepared mixture is filled in a mold and hot-press molded in a reduced pressure atmosphere using a pulse current sintering apparatus to obtain a molded body.
The reduced pressure atmosphere is, for example, an atmosphere of 6 Pa or less, preferably 4 Pa or less.
The pressure at the time of pressurization is 20 MPa or more, for example, and 20-40 MPa is preferable.
Moreover, ultimate temperature is 40-200 degreeC, for example, 110-150 degreeC is preferable and 120-140 degreeC is more preferable.
As other conditions, the temperature rising rate is, for example, 5 to 50 ° C./minute, the holding time at the ultimate temperature is, for example, 0 to 500 seconds, and the temperature decreasing rate is, for example, 5 to 50 ° C./minute.

  In addition, it is preferable to dry the obtained molded object suitably, regardless of the aspect of hot press molding. The drying condition is not particularly limited, but is preferably a condition in which the moisture content of the molded product is 1% or less. Specifically, for example, it is left at 80 to 120 ° C. for 5 to 20 days in a vacuum.

<Molded body>
Next, the molded product of the present invention will be described.
The molded body of the present invention is a molded body formed by molding a material containing hornet silk, and has a flexural modulus of 5.0 GPa or more. The bending elastic modulus of the molded body of the present invention is preferably 5.5 GPa or more, and more preferably 6.0 GPa or more. In addition, the measuring method of the bending elastic modulus in this invention is mentioned later.
Such a molded article of the present invention is substantially a molded article obtained by the production method of the present invention described above.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

[Test Example 1]
<Production of molded body: Example 1>
First, a cocoon collected from a hornet's nest was cut into a length of about 10 mm, and impurities were removed by hand sorting within a range that could be visually confirmed.
Then, using a planetary ball mill (alumina container: 500 mL, alumina balls: φ15 mm, φ20 mm, total amount 3.2 kg), rotating at 300 rpm for 1 minute, stopping for 5 minutes 10 times and grinding And powdered.
After the pulverization, the obtained powder was classified using a magnetic sieve shaker. In Example 1, fine particles (particle size: less than 75 μm) were used.
Thereafter, electrostatic sorting was performed using a small high voltage power source manufactured by Green Techno Co., and impurities were removed from the powder. Electrostatic sorting is usually performed by using both the specific gravity difference and the attractive force due to static electricity in a rotating drum. Here, the electrostatic sorting is performed without using the specific gravity difference. Was done. In this way, a powder (hereinafter, also referred to as “hornet silk powder”), which is a material containing hornet silk, was obtained.

  Next, the obtained hornet silk powder is filled into a steel mold and heated in the atmosphere using a hot press (Toyo Seiki Seisakusho, mini TEST PRESS 10), pressure: 30 MPa, temperature: 170 ° C. A compact was produced by hot pressing under conditions of time: 300 seconds and press time: 300 seconds.

<Preparation of molded body: Examples 2-3>
The process of obtaining hornet silk powder from cocoons collected from hornet nests was different from that in Example 1.
Specifically, first, lithium bromide (LiBr) was dissolved in distilled water to prepare a 9 mol / L LiBr aqueous solution as a neutral salt aqueous solution. In the prepared LiBr aqueous solution, 200 mg of cocoon collected from the hornet's nest was added, and stirred at 40 ° C. for about 1 hour until there was no undissolved material other than impurities. The LiBr aqueous solution after stirring was centrifuged to separate and remove insoluble impurities.
Next, the LiBr aqueous solution from which impurities have been removed is put into a dialysis tube made of cellulose (Wako Pure Chemical Industries, seamless cellulose tube, small size 18), and dialysis is performed at room temperature in distilled water for 4 days to remove LiBr. did.
After dialysis, the contents of the dialysis tube are filtered through a glass filter (G-4) to recover the solid content. The recovered solid content is lyophilized for 2 days, and then subjected to the same conditions as in Example 1. By pulverizing, hornet silk powder was obtained.
Next, the obtained hornet silk powder was classified by performing sieving using an electromagnetic sieve shaker. In Example 2, fine particles (particle size: less than 75 μm) were used, and in Example 3, coarse particles (106 μm or more and less than 250 μm) were used.
The hornet silk powder thus obtained was hot-press molded in the same manner as in Example 1 to produce a molded body.

<Production of molded body: Comparative Example 1>
Using a commercially available silk powder (manufactured by KB Seiren, IM type, average particle size 7 μm), hot pressing was performed in the same manner as in Example 1 to prepare a molded body.

<Evaluation of molded body>
The molded bodies of Examples 1 to 3 and Comparative Example 1 were evaluated as described below. The evaluation results are shown in Table 1 below.
Before the evaluation, the molded body was left to dry in a vacuum at 100 ° C. for 10 days. The moisture content of the molded body after drying was 1% or less in all cases.

(Flexural modulus)
About the molded bodies of Examples 1 to 3 and Comparative Example 1, the flexural modulus was measured using an autograph (manufactured by Shimadzu Corporation, AGS-1kNSTD) in accordance with JIS K 7171 (Plastic-Determination of bending characteristics). Was measured.

(Vickers hardness)
About the molded bodies of Examples 1 to 3 and Comparative Example 1, using a micro hardness tester (manufactured by Shimadzu Corporation, HMV-G20), in accordance with JIS Z 2244 (Vickers hardness test-test method), Vickers hardness Was measured.

As is clear from the results shown in Table 1 above, the molded bodies of Examples 1 to 3 manufactured using Hornet silk powder were compared with the molded body of Comparative Example 1 manufactured using conventional silk powder. The bending elastic modulus showed a higher value.
Moreover, compared with the molded object of Comparative Example 1, the molded object of Examples 1-3 showed a higher value also in Vickers hardness.

  In addition, when Example 1 and Example 2 are contrasted, it is the Example which removed the contaminant by performing centrifugation after melt | dissolution in LiBr aqueous solution rather than the molded object of Example 1 which removed the contaminant by electrostatic selection. The molded body of 2 showed a higher flexural modulus. This is considered to be because the impurities in Example 2 were able to remove impurities more accurately than in Example 1 when obtaining hornet silk powder.

[Test Example 2]
<Production of molded body>
First, a hornet silk powder was obtained in the same manner as in Examples 2 to 3 of Test Example 1 described above (that is, the removal of contaminants was “dissolved / centrifugated”).

Next, the obtained hornet silk powder was sieved using an electromagnetic sieve shaker and classified as shown in Table 2 below.
Specifically, the particle size is “32 μm to less than 53 μm”, “53 μm to less than 75 μm”, “75 μm to less than 106 μm”, “106 μm to less than 150 μm”, “150 μm to less than 212 μm”, “212 μm to less than 250 μm”, and A hornet silk powder of “250 μm or more and less than 355 μm” was obtained.

Thereafter, the hornet silk powder of each particle size was subjected to hot-pressure molding in the same manner as in Example 1 of Test Example 1 described above to produce a molded body.
Two or four shaped bodies were prepared for each particle size. Specifically, four molded bodies are produced only when a hornet silk powder having a particle size of “212 μm or more and less than 250 μm” is used, and in the case of other particle sizes, two molded bodies are produced. did.

<Evaluation of molded body>
The produced molded body was evaluated as described below. The evaluation results are shown in Table 2 below. The results shown in Table 2 below are average values of the evaluation results for two or four molded bodies.
Before the evaluation, the molded body was left to dry in a vacuum at 100 ° C. for 10 days. The moisture content of the molded body after drying was 1% or less in all cases.

For each molded body, using an autograph (AGS-1kNSTD, manufactured by Shimadzu Corporation), in accordance with JIS K 7171 (Plastic-Determination of bending characteristics), from the stress-strain curve, bending fracture stress, bending fracture Strain and flexural modulus were determined.
Further, the area under the stress-strain curve was determined as energy required for destruction of the molded body (referred to as “absorbed energy”). Absorbed energy is a measure of the toughness of the compact.

  As shown in Table 2 above, the “flexural modulus” of the molded body was good, but no significant change was observed depending on the particle size of the used hornet silk powder.

  On the other hand, the “bending fracture stress”, “bending fracture strain” and “absorbed energy” of the molded product tended to be better as the particle size of the used hornet silk powder was smaller. . In particular, when the particle size of the hornet silk powder was less than 150 nm, the particle size was even better than when the particle size was 150 nm or more.

In addition, as shown in Table 2 above, the molded products having a particle size of “106 μm or more and less than 150 μm”, “150 μm or more and less than 212 μm” and “212 μm or more and less than 250 μm” have an upper limit value and a lower limit value of the particle size. The difference is 70 μm or less.
The bending elastic moduli of these molded products were the same as those of Example 3 of Test Example 1 described above (the particle size was “106 μm or more and less than 250 μm”, and the difference between the upper limit value and the lower limit value of the particle size exceeded 70 μm. The former was higher than the flexural modulus of the molded body).

Claims (8)

  The manufacturing method of a molded object which obtains a molded object by pressurizing and heating the material containing hornet silk in a shaping | molding die.   The manufacturing method of the molded object of Claim 1 whose material containing the said hornet silk is a material obtained by removing the foreign material containing the wood waste which comprises the said nest from the cocoon extract | collected from the wasp nest.   The manufacturing method of the molded object of Claim 1 or 2 whose state of the material containing the said hornet silk is a powder.   The manufacturing method of the molded object of Claim 3 whose particle size of the material containing the said hornet silk is 400 micrometers or less.   The manufacturing method of the molded object of Claim 3 whose particle size of the material containing the said hornet silk is less than 150 micrometers.   The manufacturing method of the molded object of any one of Claims 3-5 whose difference of the upper limit and the lower limit of the particle size of the material containing the said hornet silk is 70 micrometers or less.   The manufacturing method of the molded object of any one of Claims 1-6 whose temperature at the time of the said heating is 100 degreeC or more. A molded body formed by molding a material containing hornet silk,
A molded article having a flexural modulus of 5.0 GPa or more.