Functional japanese paper sheet and its manufacturing method

Abstract

To provide a Japanese paper sheet which has photocatalytic activity to generate active oxygen even in visible light or weak ultraviolet light, has self-cleaning action, maintains antibacterial or antiviral effect by the effect of plaster in a place not exposed to light, has deodorizing effect by securing a large surface area by using the Japanese paper, and can determine the time of replacement by irradiation with a black light.SOLUTION: The present invention is characterized in that it is formed by processing Japanese paper with an aqueous solution in which titanium oxide, lime plaster, and a fluorescent whitening agent are dispersed, squeezing it, and drying it.SELECTED DRAWING: None

Description

[Technical field]

[0001] This invention relates to a functional washi paper sheet with antibacterial and antiviral activity that can be used in locker rooms and other places. [Background technology]

[0002] Titanium oxide has catalytic activity in photochemical reactions, and when irradiated with ultraviolet light, it activates oxygen in the air to generate active oxygen, etc. The generated active oxygen exhibits strong oxidizing properties, oxidatively decomposing various substances, and is known to have strong antibacterial properties (see, for example, Patent Documents 1 and 2).

[0003] However, there was a major drawback in that the above-mentioned effects could not be achieved in environments with weak light, such as indoor lighting, or in environments with no light at all.

[0004] On the other hand, plaster is a natural material and has a fine pore structure. This pore structure allows plaster to absorb and store moisture, absorbing moisture when the humidity is high and releasing humidity when the humidity is dry, thereby regulating the humidity in the room. This has the effect of maintaining a comfortable indoor environment. In addition, the surface of plaster has a fine uneven structure, and these unevennesses have the function of catching dust and fine particles. Dust that adheres to the surface of plaster is easily peeled off by changes in humidity and wind, and has the effect of reducing suspended matter in the air in the room. Furthermore, plaster becomes alkaline when wet with water, which has the effect of suppressing the growth of mold and bacteria, and can prevent the growth of mold. However, since plastered walls are applied with a trowel, the finish depends on the skill of the plasterer, and if the finish is not smooth, fine unevenness will remain on the surface. These unevennesses can cause dirt and dirt to accumulate on the wall and the growth of mold. Therefore, efforts have been made to improve on the advantages of conventional plaster and other plastered walls, and wall materials and finishing methods using inorganic materials have been disclosed. However, no mention or suggestion has been made of uses or applications other than as architectural finishing materials (see, for example, Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-155598 [Patent Document 2] Japanese Patent Application Publication No. 9-225319 [Patent Document 3] JP 2001-193253 A [Patent Document 4] JP 2003-64840 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved is to create antibacterial and antiviral properties on a washi paper sheet regardless of the brightness of the light, and further, to make these properties evident according to the fluorescence emitted when irradiated with a black light. [Means for solving the problem]

[0007] The inventors conducted extensive research to solve the above problems, and as a result, they succeeded in developing a washi sheet that retains antibacterial and antiviral activity in both light and dark places, by passing a sheet of washi paper through a treatment solution containing a mixture of titanium oxide, lime plaster and a fluorescent agent, similar to the padding process used in dyeing, squeezing it with a mangle and drying it, thereby allowing titanium oxide, lime plaster and a fluorescent brightener to coexist on the surface of the washi sheet, and furthermore, has the function of allowing a decrease in such activity to be detected by a decrease in the amount of light emitted by the fluorescent brightener. Effect of the Invention

[0008] This invention provides a functional washi sheet that maintains antibacterial and antiviral activity in both light and dark, and can determine the decline in activity of titanium oxide and plaster by the decline in the amount of luminescence from the fluorescent whitening agent, making it clear when to replace the sheet. Furthermore, because washi paper was selected as the base material, it has a large surface area and is expected to have a high deodorizing effect and humidity control effect.

[0009] According to the present invention, by using the functional washi paper sheet with antibacterial and antiviral activity of the present invention in environments with weak light such as locker rooms and cages in hot spring facilities, or in environments with no light at all, the antibacterial and antiviral properties can be exhibited, and places and tools used by an unspecified number of people can be kept hygienic. Furthermore, by irradiating with black light, the presence or absence of functional components and the amount of adhesion can be determined according to the luminescence intensity of the fluorescent whitening agent, which is useful for clarifying the time to replace the functional washi paper sheet with antibacterial and antiviral activity of the present invention.

[0010] The functional washi paper sheet of the present invention, which has been given antibacterial and antiviral activity, can be shaped freely and installed anywhere, for example, in bathroom lockers, baskets, supplies in nursing homes, hospitals, wallpaper, interior decoration, curtains, roll curtains, sheets, rugs, tablecloths, car seats, shoe soles, etc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below with reference to the following embodiments. Note that the present invention is not limited to the following embodiments and implementations, and can be carried out with appropriate modifications. EXAMPLES

[0012] As the titanium oxide, any aqueous solution containing anatase type titanium oxide dispersed in water may be used. For example, aqueous photocatalytic treatment solution Titanal (registered trademark) from Fushimi Co., Ltd., and aqueous anatase type titanium oxide solutions TA100, TA200, TA300, TA301, and TA500 from Fuji Titanium Industry Co., Ltd. may be used as long as they are dispersed in an aqueous solution.

[0013] Rutile and anatase photocatalysts may be used, for example, Double Care Coat (registered trademark) from Wako Filter Technology Co., Ltd. In this case, the fabric is pretreated with a rutile titanium oxide solution.

[0014] The plaster used was the same as that used in repairing Himeji Castle. The characteristic of Japanese plaster is that it is a mixture of slaked lime, susa (a binder made of straw or paper), and nori (mainly seaweed glue such as hornwort). Plaster is a wall material with excellent moisture-regulating, deodorizing, antibacterial, and durability, and is said to last for 100 years. It is an ideal material for this application, especially in bathrooms. This plaster was used in this example. Plaster contains natural organic binder components, so even if a titanium oxide aqueous solution that does not contain binder components is used, titanium oxide can be fixed to the surface of the Japanese paper. Also, if an organic binder is mixed into the titanium oxide solution, slaked lime (calcium hydroxide) or quicklime (calcium oxide) can be used instead of plaster.

[0015] Examples of the fluorescent whitening agent include stilbene-based, coumarin-based, imidazole-based, triazole-based, and oxazole-based agents, among which stilbene-based agents, particularly 2'2-(1,2-ethenedinyl)bis(5-methylbenzoxazole)-based fluorescent dyes containing a bluing dye, are preferred. A specific example of a product that can be preferably used is the cotton fluorescent dye Illuminal BGF manufactured by Showa Kako.

[0016] The washi paper used was a washi paper sheet made by inserting weft threads made of washi paper into the stitches of a knitted fabric made of warp fibers such as polyester from Fujilace Co., Ltd. Washi paper is usually supplied in rolls. However, if it is directly processed into washi paper, it is difficult to process because the washi paper tears during processing. In addition, in order to minimize dimensional changes during drying, it is dried while being pulled by a stretching device such as a tenter, so it is also prone to damage. In addition, since the finished product is used in various shapes, the washi paper itself is prone to wrinkles and requires heat treatment such as an iron to stretch it again. By using a washi paper sheet made by inserting weft threads made of washi paper into the stitches of a knitted fabric made of warp fibers such as polyester from Fujilace Co., Ltd., damage during processing can be prevented and the finished product can be used in various shapes. In addition, the characteristics of "washi paper" are generally said to be "the fibers are much longer than Western paper, so it is strong even though it is thin, has a relatively long life, and has a unique texture." Washi paper also has a warm appearance and a pleasant texture. Washi paper is traditionally made in Japan, and is mainly made from plant fibers. It is generally made by hand, and there are many different types of paper depending on the manufacturing method. Fujilace Co., Ltd. has succeeded in mechanically producing this washi paper and using a warp knitting machine to turn it into washable washi fabric, and has collaborated with inventors to develop a variety of products. Washi paper is breathable and absorbent, making it well suited to Japan's humid climate, and has long been rooted in Japanese lifestyle and culture.

[0017] As a method using only anatase-type photocatalyst, the processing method for Japanese paper sheets was to add 1g of lime plaster and 0.01g of Illuminal BGF to 1L of water diluted 5 times with titanal, mix well, and immerse the Japanese paper sheets in a bath ratio of 1:20. After immersion, squeeze out the water well and place in a drying oven to dry at 90℃ for about an hour.

[0018] Similarly, when processing a two-liquid type photocatalyst of rutile and anatase type, pre-coat with Double Care Coat's rutile type titanium dioxide solution, then add 1g of lime plaster and 0.01g of Illuminal BGF to 1L of anatase type titanium dioxide solution, mix well, and immerse the washi paper sheet in a bath ratio of 1:20. After immersion, squeeze out the water well and dry in a drying oven at 90℃ for about an hour.

[0019] In this case, the amount of adhesion relative to the weight of the washi sheet was 0.1-0.2wt% for plaster, 0.8-1.4wt% for titanium dioxide, and 0.005-0.009wt% for fluorescent whitening agent. If the surface area of ​​the material is about twice as large, the amount of adhesion will be about twice as much. However, if it is more than three times as large, the cost will increase significantly, so it is desirable to adhere to an amount of adhesion of three times or less.

[0020] The antiviral effect of the processed washi paper was evaluated by the following procedure, based on JIS L 1922 "Antiviral Test Method for Textile Products." 50 It was done by law. (1) The fabric was cut into pieces measuring 20 mm x 20 mm and stacked to a mass of 0.4 g. These were then placed in a vial. Three test samples were prepared, and six blank samples were prepared by treating JIS fastness white cotton cloth in the same manner. 200 μL of each test solution was dropped onto each test sample and then dried. (2) The vial containing the material was wrapped in aluminum foil with the lid separate, and the vial containing the sample was covered with aluminum foil, and both were sterilized in an autoclave (121°C, 20 minutes). After sterilization, the vial was immediately dried in a clean bench. After drying, the vial was closed and the sample was kept clean until testing. (3) The influenza virus (PR8 strain) was used as the virus. The initial infection concentration of the virus was 10 7 TCID 50 / mL. (4) 200 μL of the above virus solution was dropped onto the sample prepared in (2) and absorbed, then the lid was closed and the container was left to stand for 2 hours at 25° C. Triplicate samples were used for each test. (5) For the three blank samples, the infectivity was also measured immediately after the virus was dropped. The reason for this was to confirm whether the infectivity of the virus was maintained immediately after dropping and after leaving it to stand for two hours. In other words, this was to prove that the infectivity of the virus had not decreased even after two hours had passed. If the difference in the infectivity decreases by one digit (90%) or more, the test is not valid. (6) Each of the samples (4) and (5) was added to 20 mL of SCDLP medium (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and stirred thoroughly to wash out any viruses adhering to the sample. (7) Using this virus washout solution as the stock solution, a 10-fold dilution series was prepared. 100 μL of the stock solution was taken and added to 900 μL of dilution solution to obtain a 1 / 10 dilution solution, and by repeating the same process, virus dilutions of 1 / 100, 1 / 1000, 1 / 10000, etc. were prepared. In this case, a medium commonly used for influenza viruses (Opti-MEM I Reduced Serum Medium, hereafter referred to as growth medium) was used for dilution. (8) Unlike bacteria, viruses cannot replicate on their own, so they must infect cells and grow. In this study, we used MDCK cells (short for Madin-Darby canine kidney cells), which are commonly used in influenza virus tests. MDCK cells were cultured in a 96-well microplate before use. Before adding the virus dilutions, the cell surface was washed with growth medium containing 0.25% trypsin (hereafter, maintenance medium). The washing was performed twice by adding 100 μL of maintenance medium to each well and then turning the well upside down to drain the medium. In this case, to prevent the cells from drying out, the second draining operation was performed immediately before dripping each virus dilution. (9) 100 μL of each diluted solution was dropped into each well. The first 8 wells were filled with the virus washing stock solution, and the second well was filled with the 1 / 10 diluted solution. This was repeated for each diluted solution. (10) Using a microplate, the same procedure was repeated starting with the original solution, filling all wells with each dilution solution. (11) The microplate was covered and placed in a CO2 incubator at 33°C for 1 hour to allow the virus to infect the cells. (12) After standing for 1 hour, each virus dilution on the microplate was removed, and 100 μL of maintenance medium was added to wash the cell surface. Then, 200 μL of maintenance medium was added to each well, and the cells were cultured in a CO2 incubator at 33°C for 7 days. (13) On the third day of culture, the cells were observed under an inverted microscope as an intermediate observation, and the state of the cells in each well was recorded in a results sheet. The same was also done after 7 days. (14) The cells in each well were observed to confirm whether they were infected or not. (15) From the above results, the virus infectivity was determined by the Behrens-Körber method, and the antiviral activity value was calculated. (16) According to the definition of the JIS, an antiviral activity value of 2.0 or higher is considered effective, and an antiviral activity value of 3.0 or higher is considered sufficiently effective.

[0021] The antibacterial properties were evaluated with reference to JIS L 1902 "Antibacterial properties test method for textile products." Staphylococcus aureus was used as the bacteria. JIS L 1902 specifies the method for evaluating whether a textile product has antibacterial properties. In this test, the extent to which microorganisms grow within a certain period of time is examined, and the antibacterial properties of the textile product are judged from the results. The procedure and test conditions are as follows. (1) As in the virus test, 200μL of each processing solution was dropped onto the test cloth and then dried. Three pieces each of the standard cotton cloth for antibacterial testing (control sample) and the test cloth (0.4g / piece) were sterilized with dry heat and then used in the experiment. (2) The control sample and the test sample were pre-mixed with 10 5 Approximately 0.2 mL of Staphylococcus aureus liquid adjusted to CFU / mL is inoculated. (3) The sample with the bacteria inoculated is cultured in a 37°C incubator (in a dark place) for 18 hours. (4) Wash out the bacteria from the sample with a washing solution (20 mL of SCDLP medium). (5) The washed bacteria are plated onto pour agar plates. (6) The agar medium with the bacteria seeded on it is cultured in an incubator at 37°C for 24 to 48 hours. (7) Count the colonies formed on the agar medium. (8) The results were then substituted into the equation defined in the JIS. According to the JIS definition, an antibacterial activity value of 2.0 or higher indicates effectiveness, and 3.0 or higher indicates sufficient effectiveness.

[0022] The deodorizing test was conducted based on the SEK Mark Textile Product Certification Standards, Chapter 6-4 Deodorizing Test, Detector Tube Method. Ammonia was used as the odor gas. The procedure is as follows: (1) Standard cotton cloth for testing (control sample) and test sample 100 cm 2 The material is conditioned at 20°C and 65% RH for 24 hours. (2) Place the control sample and test sample into a 5 L polyvinyl fluoride sampling bag, seal it, and evacuate it. (3) Fill the tank with 3L of odorous gas whose concentration has been adjusted using a permeator. (4) Leave it for 2 hours and then measure the odorous gas concentration. (5) The odor reduction rate was calculated using the following formula. Odor reduction rate [%] = ((gas concentration of control sample - gas concentration of test sample)) / gas concentration of control sample x 100

[0023] Table 1 summarizes the effects of each photocatalyst under black light (365 nm) irradiation.

[0024] [Table 1]

[0025] As shown in Table 1 above, in the dark, both anatase-type titanium dioxide and two-liquid-type titanium dioxide had antiviral activity values ​​of less than 2.0, which is the JIS definition of effective. In addition, when exposed to black light, both had antiviral activity values ​​of 3.0, demonstrating sufficient effectiveness.

[0026] The antiviral effects of mixing each photocatalyst with filtration plaster are summarized in Table 2.

[0027] [Table 2]

[0028] As is clear from the table, it has become clear that by combining both of these with lime plaster, an antiviral effect can be obtained even in dark places.

[0029] The antibacterial effect of each photocatalyst is summarized in Table 3.

[0030] [Table 3]

[0031] In the dark, the antibacterial activity value was below 2.0, indicating that titanium oxide alone did not provide antibacterial performance.

[0032] The antibacterial effect of plaster is shown in Table 4.

[0033] [Table 4]

[0034] As is clear from Table 4, plaster has a high antibacterial activity even in the dark. Therefore, by mixing it with titanium dioxide, it is possible to exert antibacterial and antiviral functions in both light and dark places.

[0035] The reason we chose washi paper as the base material was because we expected it to have a high deodorizing effect. The results of measuring the deodorizing effect of washi paper sheets are summarized in Table 5. Generally, an odor reduction rate of 80% or more is considered effective.

[0036] [Table 5]

[0037] By mixing a fluorescent agent into the titanium oxide and lime plaster mixed solution, the coated area will fluoresce when irradiated with ultraviolet light such as a black light, making it easy to check for the presence or absence of a coating layer and for uneven coating, and if the coating layer falls off over time, it becomes easy to determine whether it needs to be replaced. [Industrial Applicability]

[0038] This invention provides a washi paper sheet with antibacterial and antiviral properties. The washi paper sheet created by this invention can be used for the inside of lockers, baskets, and all kinds of other equipment, and has extremely high industrial applicability as a measure against new viral infections.

Claims

1. A method for producing a functional washi sheet, comprising a fiber treatment agent preparation step in which titanium oxide, lime plaster and a fluorescent whitening agent are uniformly dispersed in water, an adhesion step in which washi paper is immersed in the fiber treatment agent, a dehydration step in which excess fiber treatment agent is removed from the washi paper to which the fiber treatment agent has been adhered, and a drying step in which the dehydrated washi paper is dried.

2. The method for producing a functional Japanese paper sheet according to claim 1, wherein the titanium oxide has a crystal type of anatase type alone or a mixture of anatase type and rutile type, and the average particle size of the primary particles is in the range of 30 nm to 10 μm.

3. 3. The method for producing a functional Japanese paper sheet according to claim 1 or 2, wherein the plaster is made of slaked lime, quicklime, or a mixture of slaked lime or quicklime with a binder such as straw and glue.

4. The method for producing a functional washi paper sheet according to any one of claims 1 to 3, wherein the fluorescent brightening agent is at least one selected from the group consisting of stilbene-based, coumarin-based, imidazole-based, triazole-based, and oxazole-based fluorescent dyes.

5. 5. The method for producing a functional Japanese paper sheet according to claim 4, wherein the fluorescent whitening agent is a stilbene-based fluorescent dye, 2'2-(1,2-ethenedinyl)bis(5-methylbenzoxazole)-based fluorescent dye.

6. A method for manufacturing a functional washi paper sheet according to any one of claims 1 to 5, characterized in that the washi paper is formed by inserting weft threads made of washi paper into the stitches of a knitted base fabric woven from warp fibers such as polyester.

7. The method for producing a functional washi paper sheet according to any one of claims 1 to 6, wherein the titanium oxide is in the form of an aqueous solution or an aqueous dispersion.

8. The method for producing a functional washi paper sheet according to any one of claims 1 to 7, wherein the titanium oxide is in the form of an aqueous solution or aqueous dispersion further containing an organic binder.

9. A functional washi sheet with titanium oxide, lime plaster and fluorescent whitening agent attached to the fiber surface.

10. The functional Japanese paper sheet according to claim 9, wherein the titanium oxide is anatase type alone or a mixture of anatase type and rutile type, and the average particle size of the primary particles is in the range of 30 nm to 10 μm.

11. 11. The functional Japanese paper sheet according to claim 9 or 10, wherein the plaster is made of slaked lime, quick lime, or a mixture of slaked lime or quick lime with straw and glue as binders.

12. The functional washi paper sheet according to any one of claims 9 to 11, wherein the fluorescent whitening agent is at least one selected from the group consisting of stilbene-based, coumarin-based, imidazole-based, triazole-based, and oxazole-based fluorescent dyes.

13. The functional Japanese paper sheet according to any one of claims 10 to 12, wherein the fluorescent whitening agent is a stilbene-based fluorescent dye, 2'2-(1,2-ethenedinyl)bis(5-methylbenzoxazole)-based fluorescent dye.

14. The functional washi paper sheet according to any one of claims 9 to 13, characterized in that the washi paper is formed by inserting weft threads made of washi paper into the stitches of a knitted base fabric woven from warp fibers such as polyester.

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