JP3342946B2 - Silk fibroin powder coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint containing ultrafine silk fibroin powder.

[0002]

2. Description of the Related Art In recent years, various products have been proposed in which fine touch of silk fibroin is contained to improve touch feeling and moisture absorption / release properties. For example, there is an artificial leather containing fine powder of silk fibroin manufactured by blending fine powder of silk fibroin in a synthetic resin. Conventionally, various methods have been proposed for producing such fine powder of silk fibroin.

[0003] For example, according to Japanese Patent Publication No. 39-1941,
After dissolving the silk fibroin in a copper-ethylenediamine aqueous solution or the like, alcohols are added to the silk fibroin aqueous solution obtained by dialysis, the precipitate is dried, and then the dried product is pulverized to produce fine silk fibroin powder. According to Japanese Patent Application Laid-Open No. 4-300369, silk fibers are hydrolyzed with hydrochloric acid, subjected to degradation treatment, and then mechanically pulverized to produce fine silk fibroin powder.

However, fine silk fibroin powder obtained by the production method disclosed in the above-mentioned JP-B-39-1941 has once broken the structure of the silk fiber by a chemical treatment, so that the original texture of the silk fiber is impaired. There is a possibility that it has been. Also,
Even with the fine powder of silk fibroin obtained by the production method according to JP-A-4-300369, the original texture of silk may not be maintained.

[0005] Accordingly, it is not always possible to obtain good moisture absorption / desorption properties, touch feeling and anti-glare properties for various products, for example, paints containing the silk fibroin fine powder obtained by the above-mentioned conventional method. Was. In addition, since the silk fibroin fine powder obtained by the conventional method is colored yellow to green, it was difficult to obtain a pastel color, white color, pale color, or the like. Therefore, an object of the present invention is to provide a coating material containing silk fibroin ultrafine powder, which always provides good moisture absorption / desorption properties, touch feeling and anti-glare properties.

[0006]

The paint containing ultra-fine silk fibroin powder according to the present invention comprises: a first pulverizing step of pulverizing silk fibroin into coarse powder by dry mechanical pulverization means; The dry using a ball mill
A second pulverizing step of pulverizing into fine powder by a mechanical mechanical pulverizing means , and using a jet mill of the fine powder of silk fibroin .
A third pulverizing step of pulverizing into an ultrafine powder having an average particle diameter of 10 μm or less by dry mechanical pulverizing means , and in at least one of the first to third pulverizing steps or thereafter, with respect to the silk fibroin powder. It is obtained by using an ultrafine powder of silk fibroin produced by subjecting it to a β-treatment and blending the ultrafine powder of silk fibroin into a resin.

The average particle size of the coarse powder is approximately 100 μm.
m. The average particle size of the fine powder is approximately 20 μ
m. The dry mechanical pulverizing means used in the first pulverizing step may be any means such as a rotary blade mill . As described above, by combining the pulverizing steps by the dry mechanical pulverizing means into three stages so that powders having a small particle diameter are obtained sequentially, an ultrafine powder that cannot be obtained by only one mechanical pulverization can be obtained. Will be obtained.

[0008] Further, since all the steps are dry, the work is simple, and the original texture of silk is maintained. The β-treatment is a treatment in which silk fibroin is immersed in an appropriate liquid in order to increase the ratio of the β structure, and examples of the liquid for this treatment include an organic solvent. Specific examples of the organic solvent include alcohols such as methanol and ethanol, and acetone. The β-treatment may be performed at least once in or after any of the first, second, and third pulverizing steps, and may be performed two or more times as necessary.

By performing such a β-treatment, the degree of crystallinity increases. And preferably 70% of natural silk
By making the above crystallinity, when producing paint,
The ultrafine silk fibroin powder can be uniformly dispersed in the resin. As a result, a paint excellent in moisture absorption / desorption properties, anti-glare properties and touch feeling, and also excellent in antistatic performance while maintaining the texture unique to silk can be obtained. Further, since the ultrafine powder has a good whiteness, it is easy to develop all colors of the paint. Furthermore, since the ultrafine powder has good wettability on the surface, it can be easily incorporated into an aqueous resin.

The resin of the present invention includes a solvent-based resin and a water-based resin. Examples of the solvent-based resin include an acrylic resin, a urethane resin, an alkyd resin, an amino resin, and the like, and these may be used alone or as a mixture of two or more. Examples of the aqueous resin include vinyl acetate emulsions, acrylic emulsions, urethane emulsions, and the like, or water-soluble acryl, water-soluble urethane, water-soluble epoxy, water-soluble alkyd, and the like. use.

The paints include oil paints, fiber derivative paints, synthetic resin paints, rubber derivative paints, water paints and the like. Solvents for solvent-based paints include thinner, dimethylformamide, methyl ethyl ketone, toluene, isopropyl alcohol and the like. In the paint of the present invention, depending on the purpose of stabilization of quality and the use environment, additives usually used in this field, such as dispersants, antifungal agents, crosslinking agents, curing agents, ultraviolet absorbers and the like In addition, a necessary amount of a processability improver such as a plasticizer, a stabilizer, and a film forming agent, a filler, a coloring agent such as a dye or a pigment, or an extender pigment may be added.

The mixing ratio of the ultrafine silk fibroin powder to the resin is in the range of 90 to 1 wt% of ultrafine silk fibroin powder to 10 to 99 wt% of resin solids. The ratio of the ultrafine powder is
If it exceeds 90% by weight, the coating film after drying and fixing becomes brittle,
If it is less than 1 wt%, there is no effect of the addition. However, the content of the ultrafine powder in the coating film is preferably 5 to 50% by weight. It is preferable that the ultrafine powder is uniformly dispersed in the coating film. Further, the ultrafine powder may be exposed on the surface, and in this case, it is useful for further improving the touch feeling, the warm feeling and the anti-glare effect.

The object to be coated with the paint is metal, glass,
Resin, paper, ceramics, wood, etc. are optional. In addition, the coating method of the paint may be selected from brush coating, spray coating, electrostatic coating, airless coating, powder coating, etc., depending on the object to be coated, coating conditions, drying conditions, and coating scale. it can.

The paint according to the present invention can improve the moisture absorption and desorption properties, so that traces and stains such as fingerprints are less likely to adhere.
Further, the paint according to the present invention has an antiglare effect and does not reflect light, so that it is suitable for interiors of automobiles and the like. And since it becomes calm color tone, it can give a sense of quality.
Furthermore, since the paint according to the present invention can provide a good touch feeling, it is suitable for painting a part of a home appliance, a stationery, etc., which is touched by human hands.

[0015]

EXAMPLES The ultrafine silk fibroin powder used in this example was obtained as follows. First, raw silk was cut into 2-3 cm with a cutter blade mill, and then refined by immersing silk fibroin in warm water or warm water containing enzymes to obtain a silk fibroin raw material from which sericin was completely removed. If unrefined silk fibroin is used as a raw material, the resulting powder may have a reduced touch feeling or cause a light brown coloration.

Next, the cut silk fibroin is fed to a rotary blade mill [Orient hard type pulverizer V manufactured by Orient Co., Ltd.]
M-32 (trade name)] and crushed into a silk fibroin coarse powder having an average particle size of about 100 μm, and then placed in a fluidized drier or the like, and dried at 100 ° C. for 6 hours. The temperature condition for this drying is 130 ° C. or less, preferably 90 ° C.
~ 110 ° C. If it is higher than 130 ° C, it may turn yellow. The time is set to one hour or more. If the drying is not performed sufficiently, when the ball mill wall surface is made of general stainless steel at the time of the subsequent ball mill pulverization, the ball mill wall surface will be worn and the powder will be colored intensely. However, when the wall material of the ball mill is made of a material that does not cause coloring problems, such as ceramics, it is not necessary to perform sufficient drying.

In the present embodiment, the particle size of the powder was measured using a laser rotary particle size analyzer [SK LAS manufactured by Seishin Enterprise Co., Ltd.].
ER PRO 7000S (trade name), dispersion medium: ethanol, dispersion condition: ultrasonic wave 60 seconds]. Next, using a ball mill (manufactured by Kondo Kagaku Seisakusho), the silk fibroin coarse powder was pulverized for 12 hours to obtain a fine silk fibroin powder having an average particle size of about 20 μm. The ball mill has a wall made of ceramic and a ball made of alumina in order to prevent coloring of the powder.

Although the average particle diameter can be reduced to 20 μm or less by this ball mill pulverization, jet mill pulverization can be performed at such a particle diameter and the average particle diameter can be reduced to 20 μm in consideration of working efficiency.
The ball mill pulverization is completed at about μm. That is, if it is attempted to further reduce the particle size by a ball mill, it takes much time, and there is no great difference in the particle size of the particles obtained by the subsequent jet mill pulverization.

After the fine silk fibroin powder taken out of the ball mill is transferred to a cylindrical tank, methanol is poured into the tank and stirred at room temperature for 1 hour to increase the degree of crystallinity. Process and continue,
The fine silk fibroin powder was taken out of the tank and the fine silk fibroin powder was dried. By performing the β-treatment, the obtained powder can be dispersed well in a resin solution or the like for producing a product. Next, the fine powder of the silk fibroin was pulverized using a jet mill (Single Track Jet Mill (trade name) manufactured by Seishin Enterprise Co., Ltd.) to obtain an ultrafine powder having an average particle size of 3.252 μm. The processing amount at the time of this pulverization was 5 kg / h.

Example 1 A coating material according to this example was prepared by blending and mixing 10% of the ultrafine silk fibroin powder in a solvent-based urethane resin solution. Next, the paint was spray-painted on an ABS plate (2 mm thick) with a spray gun (manufactured by Iwata Coating Machine Industry Co., Ltd.).

Example 2 In Example 1, an aqueous urethane resin emulsion (Superflex 41) was used in place of the solvent urethane resin solution.
0 (trade name, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and painted in the same manner as in Example 1. Example 3 Same as Example 1, except that an iron plate (2 mm thick) was used as the object to be coated.

COMPARATIVE EXAMPLE 1 Same as Example 1, except that the ultrafine silk fibroin powder was not mixed in the resin. Comparative Example 2 A coating material was prepared in the same manner as in Example 1, except that 10% of silica powder was blended in place of the silk fibroin ultrafine powder to prepare a coating material.

COMPARATIVE EXAMPLE 3 Same as Example 2, except that ultrafine silk fibroin powder was not mixed in the resin. Comparative Example 4 A coating material was prepared in the same manner as in Example 1 except that 10% of silica powder was blended in place of the ultrafine silk fibroin powder to prepare a coating material. Comparative Example 5 Same as Example 3, except that an iron plate (2 mm thick) was used as the object to be coated.

Hygroscopicity, touch feeling, antiglare property and electrification of paint
Evaluation of prevention performance The paints of the above Examples and Comparative Examples were evaluated for moisture absorption, touch feeling, antiglare properties and antistatic performance as follows. (1) Method of evaluating hygroscopicity Using a brush, water was applied on the coating film in a size of 2 cm in width and 3 cm in length, and the time required for drying was visually measured. Table 1 shows the results. (2) Evaluation method of touch feeling Twenty arbitrarily selected persons were allowed to touch the coating film, and the touch was evaluated as excellent, good, or bad. Table 1 shows the results.

(3) Method of evaluating antiglare property A sample is placed on a desk, and the sample is irradiated with strong light from one side of the desk to the other side. Then, a person sitting on the other side of the desk was asked whether the reflected light from the sample was dazzling. The number of people involved in the evaluation is 20. The light source used was a reflex lamp
500W for daylight color (Matsushita Electric Industrial Co., Ltd.)
It is. Table 1 shows the results. In the table, ○ means not dazzling and × means dazzling. (4) Evaluation method of antistatic performance According to JIS-L1094B, the sample was rubbed with a cotton cloth, and the charged voltage after 1 minute was measured. To measure this charged voltage, use a rotary static tester (Model: RST-20
1, Koa Shokai Co., Ltd.) was used. Table 1 shows the results.
Shown in

[0026]

[Table 1]

From Table 1, it can be seen that the paints of Examples 1 to 3 are excellent in hygroscopicity and touch feeling because they contain the ultrafine silk fibroin powder of the present invention. In addition, it has excellent antiglare properties and antistatic performance. In particular, the antistatic performance is about 1/3 or less of the comparative example.

On the other hand, since the paints according to Comparative Examples 1, 3, and 5 do not contain the ultrafine silk fibroin powder of the present invention,
It can be seen that the hygroscopicity and touch feeling are inferior. Also,
The anti-glare property and antistatic performance are also inferior. Also,
Since the paints according to Comparative Examples 2 and 4 contain silica powder instead of the ultrafine silk fibroin powder of the present invention, the paints of Examples are inferior in hygroscopicity and touch feeling. You can see that. Further, even if there is no problem with respect to the antiglare property, the antistatic performance is poor.

[0029]

According to the paint containing the ultrafine powder of silk fibroin according to the present invention, good moisture absorption / desorption property and touch feeling can always be obtained. In addition, it has excellent antiglare properties and antistatic properties.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-297411 (JP, A) JP-A-63-291652 (JP, A) JP-A-7-279053 (JP, A) JP-A-7-790 278441 (JP, A) JP-A-4-337331 (JP, A) JP-A-6-339924 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 5 / 00-201 / 00 C08J 3/12 B02C 1/00-25/00 B29B 13/10

Claims (4)

(57) [Claims] 1. A first pulverizing step of pulverizing silk fibroin into a coarse powder by a dry mechanical pulverizing means , and a second pulverizing step of pulverizing the silk fibroin coarse powder into a fine powder by a dry mechanical pulverizing means using a ball mill. A pulverizing step, and a third pulverizing step of pulverizing the fine powder of silk fibroin into an ultrafine powder having an average particle diameter of 10 μm or less by dry mechanical pulverizing means using a jet mill, During at least one of the milling steps or thereafter, β
A silk fibroin ultrafine powder-containing paint obtained by using a silk fibroin ultrafine powder produced by subjecting the composition to a plasticization treatment and blending the silk fibroin ultrafine powder into a resin. 2. The paint containing ultrafine silk fibroin powder according to claim 1, wherein said resin is a solvent-based resin. 3. The paint containing ultrafine silk fibroin powder according to claim 1, wherein said resin is an aqueous resin. 4. The method according to claim 1, wherein
In the paint containing ultra-fine silk fibroin powder, the mixing ratio of the ultra-fine silk fibroin powder and the resin is
10% to 99% by weight of fat solids, 90% silk fibroin powder
Silk fibroin characterized by being in the range of 1 wt% to 1 wt%
Ultra fine powder containing paint.