JP3373039B2 - Silk fibroin ultra fine powder containing ink - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink containing ultrafine silk fibroin powder and can be used for surface printing of plastic, glass, metal or the like or precoating of a printing surface. 2. Description of the Related Art In recent years, various products have been proposed in which silk fibroin fine powder is contained to improve the feel and moisture absorption / desorption 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 Japanese Patent Publication No. 39-1941 has once destroyed 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] Therefore, for various products, such as inks, containing the silk fibroin fine powder obtained by the above-mentioned production method, good moisture absorption / desorption properties, writing acceptance characteristics and excellent feel due to the moisture absorption / desorption properties. Was not always available. Therefore, an object of the present invention is to provide an ink containing ultrafine powder of silk fibroin, which can always obtain good moisture absorption / desorption properties, writing acceptability and feel. [0006] The ink containing the ultrafine powder of silk fibroin according to the first invention of the present invention is a method of pulverizing silk fibroin into coarse powder by dry mechanical pulverization means.
Crushing process and the above-mentioned silk fibroin coarse powder is ball milled
A second crushing step of crushing to a fine powder with a dry mechanical grinding means using a jet mill the silk fibroin fine powder
A third pulverizing step of pulverizing into ultrafine powder having an average particle size of 10 μm or less by dry mechanical pulverizing means using
The silk fibroin ultrafine powder produced by subjecting the silk fibroin powder to β-treatment during or after at least one of the third pulverization steps is used, and the silk fibroin ultrafine powder is blended into the ink component. It was obtained. 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 size are obtained sequentially, an ultrafine powder which 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 manufacturing products,
The ultrafine silk fibroin powder can be uniformly dispersed in various inks. As a result, a product excellent in moisture absorption / release properties, moisture permeability, and feel can be obtained while maintaining the texture unique to silk. Inks are roughly classified into solvent-based and water-based inks, and the present invention is applicable to both inks. The main components of the ink component are a base resin, a solvent, an auxiliary, and a pigment. The content of each component is as follows. The main resin type of the base resin ink base includes acryl, urethane, vinyl, epoxy, cellulose, chlorinated polyolefin, and the like, and one or a mixture of these is selected and used. On the other hand, at present, water-based inks and paints are being developed in view of environmental problems. Regarding the ink of the present invention, the printing target,
It is necessary to determine the type of resin to be used depending on conditions such as the purpose and environmental problems. In the case of solvent-based inks, various types of solvents such as aliphatic, ketone, alcohol, aromatic, and ether are used. The type of solvent to be used is selected depending on the type of resin, printing target, printing method, purpose, and the like, and the content is determined accordingly. Auxiliaries are selected according to the purpose, printing target, printing conditions and the like.
The purpose includes various purposes such as enhancement of film physical properties and improvement of setability. Pigment A pigment is generally used for coloring an ink or for giving a mat tone or the like. The proportion of each component in the ink of the present invention is arbitrary, and is, for example, as follows. Resin component: 5-30% Pigment component: 0-40% Silk fibroin: 5-90% Solvent component: Remaining amount This ink is used for screen printing, gravure printing, flexo printing, pad printing, etc. Printing can be performed on the surface to be printed using a general printing method. In the present invention, since the ink contains the silk fibroin of the present invention, excellent hygroscopicity can be imparted to the ink coating film. This makes it possible to easily overwrite the ink film with a writing instrument. Then, the writing quality at the time of writing is greatly improved, and the abrasion resistance of the character is also improved. Further, since the coating film obtained by the present ink has a good feel, it is suitable for use on parts touched by humans, such as home appliances and stationery. Furthermore, since it has a matting effect, high-quality printing can be performed. 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 an enzyme to obtain a silk fibroin raw material from which sericin was completely removed. If unrefined silk fibroin is used as a raw material, the feel of the resulting powder may be reduced,
Causes a light brown coloration. Next, the cut silk fibroin was fed to a rotary blade mill [Orient hard mill 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 the ball mill pulverization, jet mill pulverization can be performed with 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 particles obtained by the subsequent jet mill pulverization. After the fine silk fibroin powder removed from the ball mill is transferred to a cylindrical tank, methanol is poured into the tank, and the mixture is stirred at room temperature for 1 hour to increase the degree of crystallinity. 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 commercially available solvent-based ink, sericol ink (trade name,
The ink according to this example was prepared by mixing and mixing 15% of the ultrafine powder of silk fibroin obtained by the above-mentioned method with Teikoku Ink Mfg. Co., Ltd. Example 2 An ink according to this example was prepared by blending and mixing 30% of the ultra-fine silk fibroin powder obtained by the above-mentioned production method with an aqueous acrylic emulsion. Comparative Example 1 Sericol ink (trade name) which is a general ink itself. Comparative Example 2 An ink according to this comparative example was prepared by blending and mixing 15% hydrophilic silica powder as a comparative powder with Sericol ink (trade name). Comparative Example 3 A water-based acrylic emulsion itself. Comparative Example 4 30 hydrophilic silica powders were added to an aqueous acrylic emulsion.
% To prepare an ink according to this comparative example. Evaluation of Properties The inks of the above Examples and Comparative Examples were printed on polycarbonate plates (thickness 0.5 mm) and dry PPC paper My Paper (trade name, manufactured by Nippon Business Supply Co., Ltd.) to prepare samples. These samples were evaluated for adhesion, printability, writing acceptability, and touch functionality. (1) Adhesion This adhesion evaluation test uses a wear resistance test, and applies a load of 100 g to a friction element (plate-like member) to which Kanakin No. 3 (cotton cloth) is attached as a friction cloth. Was carried out by rubbing the surface of the sample 50 times. As a result, all of Examples 1 and 2 and Comparative Examples 1 to 4 were good in terms of ink adhesion. (2) Printability This printability evaluation test was carried out by screen-printing the sample and observing the printability. As a result, all of Examples 1 and 2 and Comparative Examples 1 to 4 were excellent in printability. (3) Writing Acceptability The sample was overwritten using the following writing instrument, and evaluated by measuring the time required for the overwritten characters to dry. The number of measurements is four or more. Table 1 shows the results. The writing instrument used was an XY plotter (water-based ink) or a brush pen (manufactured by Kuretake Seishodo Co., Ltd.) in the case of the My Paper (trade name), and an oil-based felt pen (Mitsubishi) in the case of the polycarbonate plate. Pencil Co., Ltd.) or an aqueous felt pen (Mitsubishi Pencil Co., Ltd.). The XY plotter is
It is WX2400 made by Graphic Co., and the speed of the recording paper is 1cm.
/ S, the input range is 0.5V. [Table 1] According to Table 1, the samples of Examples 1 and 2 contain the ultrafine powder of silk fibroin of the present invention in the ink. It can be seen that it is significantly improved. On the other hand, since the samples of Comparative Examples 1 to 4 do not contain the silk fibroin ultrafine powder of the present invention or contain hydrophilic silica powder instead of the silk fibroin ultrafine powder, It can be seen that the drying property when overwriting is not as good as the sample of the example. (4) Tactile Functionality The tactile functionalities were determined by having 20 randomly selected in-house monitors evaluate the texture, writing quality, and sharpness of characters. The texture is an evaluation based on the feel of a solid coated film. The writing taste and the sharpness of characters are
This is an evaluation of the acceptance of writing. The evaluation criteria were five levels from 5 (good) to 1 (bad). Table 2 shows the results. [Table 2] From Table 2, it can be seen that the samples of Examples 1 and 2 contain the silk fibroin ultrafine powder of the present invention in the ink, so that the samples have good texture, writing quality and clearness of characters. It can be seen that it is. On the other hand, Comparative Examples 1 to
Sample No. 4 does not contain the silk fibroin ultrafine powder of the present invention or contains hydrophilic silica powder in place of the silk fibroin ultrafine powder.
It can be seen that at least one of the writing quality and the sharpness of the character is poor. According to the silk fibroin ultrafine powder-containing ink of the present invention, since the silk fibroin ultrafine powder of the present invention is contained, good moisture absorption / desorption properties, writing acceptability and feel are obtained. Always obtained.

Continuation of the front page (56) References JP-A-6-41483 (JP, A) JP-A-4-337331 (JP, A) JP-A-7-310019 (JP, A) JP-A-7-278472 (JP) JP-A-7-278441 (JP, A) JP-A-7-279053 (JP, A) JP-A-7-188563 (JP, A) Patent 2829220 (JP, B2) Patent 2842980 (JP, B2) Patent 2951505 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-11/20 C08J 3/12 B02C 1/00-25/00 B29B 13/10

Claims (1)

(57) [Claim 1] A first pulverizing step of pulverizing silk fibroin into a coarse powder by a dry mechanical pulverizing means, and a dry mechanical pulverizing means using a ball mill of the silk fibroin coarse powder. And a third pulverizing step of pulverizing the fine powder of silk fibroin into an ultrafine powder having an average particle size of 10 μm or less by dry mechanical pulverizing means using a jet mill. And during or after at least one of the first to third pulverizing steps, the silk fibroin powder has a β
An ink containing ultra-fine silk fibroin powder obtained by using ultra-fine silk fibroin powder produced by subjecting it to a chemical treatment and blending the ultra-fine silk fibroin powder into an ink component.