Functional paper product

Abstract

To provide a functional paper product that is water resistant, oil resistant and can be recycled.SOLUTION: A functional paper product 1 is composed of base paper 20 and a coating film 10 formed on the base paper 20, where the coating film 10 is mainly composed of a modified mannan derived from a konjak mannan from which acetyl groups are isolated, and swollen modified mannan sol of a viscosity, prior to hardening, of 3000 mPa / s or below is hardened in a state of infiltrating the gaps of cellulose fibers of the base paper 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a functional paper product that is excellent in water resistance, oil resistance and durability and can be recycled. [Background technology]

[0002] Currently, plastic packaging materials, packaging containers, food containers, straws, etc. are used in a variety of situations. They are highly water- and oil-resistant, and are highly convenient because they can accommodate a variety of items, foods, and beverages. However, environmental issues have been pointed out regarding the disposal of plastic packaging materials, packaging containers, food containers, and straws.

[0003] There is also a method of laminating paper products, including cardboard boxes and paper plates, with polyethylene film. However, this method also results in a significantly higher manufacturing cost than before, and because the paper products are laminated, they cannot be recycled.

[0004] In this situation, Patent Document 1 discloses an invention for a method for manufacturing food containers, in which water, glucomannan, and an alkali are mixed and stirred to liberate acetyl groups and inhibit swelling of modified mannan, and the swelling inhibition of the modified mannan is removed by neutralization to obtain a neutral or acidic mannan sol or a mannan gel obtained by gelling the mannan sol, which is then applied to a paper food container and dried.

[0005] According to the invention described in Patent Document 1, food containers have superior water resistance and oil resistance compared to conventional containers, have a low environmental impact, and can be produced at low cost. Furthermore, the food containers in this invention disintegrate in water and are therefore recyclable. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2021 / 166017 Summary of the Invention [Problem to be solved by the invention]

[0007] The swollen modified mannan described in Patent Document 1 has a specified viscosity, but in order to mass-produce paper products at low cost using general-purpose printing equipment owned by paper companies and printing companies, it is necessary to apply the swollen modified mannan to paper at a relatively low viscosity.

[0008] In view of the above problems, the present invention aims to provide a functional paper product that can be mass-produced using general-purpose equipment at paper companies and printing companies, has excellent water resistance, oil resistance, and durability, and is recyclable. [Means for solving the problem]

[0009] The present inventors have investigated the above-mentioned problems and have discovered that by applying the above-mentioned swollen modified mannan with a reduced viscosity when coating the base paper, the swollen modified mannan can infiltrate into the gaps between the cellulose fibers of the base paper and harden in a state in which it is intricately entangled with the cellulose fibers.

[0010] The present invention has been made based on such findings, and provides a functional paper product consisting of a base paper and a coating formed on the base paper, wherein the coating is primarily composed of modified mannan in which the acetyl groups of konjac mannan have been released, and the functional paper product is produced by hardening a swollen modified mannan sol in which the viscosity of the swollen modified mannan before hardening is 3000 mPa·s or less while infiltrating into the gaps between the cellulose fibers of the base paper. Effect of the Invention

[0011] According to the present invention, it is possible to mass-produce functional paper products that are water-resistant and oil-resistant while suppressing the generation of konjac odor, harshness, astringency, etc., efficiently and inexpensively using the existing facilities of paper manufacturers, printing companies, etc., without installing new coating equipment. Furthermore, it is possible to impart durability in addition to water-resistant and oil-resistant properties. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of (a) a conventional paper product (i.e., base paper 10 on which no coating is formed) and (b) a functional paper product 1 according to the present embodiment. [Diagram 2] (a) is a cross-sectional view of a conventional paper product, and (b) is a scanning microscope photograph of the surface of the functional paper product according to this embodiment. [Diagram 3] 1 is a graph showing the change in viscosity over time when the concentration of swollen denatured mannan is 1%. [Figure 4] 1 is a graph showing the change in viscosity over time when the concentration of swollen denatured mannan is 1.2%. [Diagram 5] 1 is a graph showing the change in viscosity over time when the concentration of swollen denatured mannan is 1.4%. [Figure 6] 1 is a graph showing the change in viscosity over time when the concentration of swollen denatured mannan is 1% or less. [Figure 7] 1 is a table showing the viscosity reduction rate depending on the temperature range and stirring time at a swollen denatured mannan concentration of 1%. [Figure 8] This is a table showing the results of a 24-hour verification test using a Garle Cobb size tester. [Figure 9] 1 is a graph and a table comparing the film thickness of swollen modified mannan sol with different paper smoothness. [Figure 10] 1 is a graph showing the results of a water resistance test of a hamburger wrapper base paper coated with swollen modified mannan sol using a coating rod No. 5. [Figure 11] 1 is a graph showing the results of a water resistance test of a hamburger wrapper base paper coated with swollen modified mannan sol using a coating rod No. 48. [Figure 12]Scanning microscope photographs of paper coated with swollen modified mannan sol, (a) shows the condition of the coated surface after one coat of swollen modified mannan sol with 300 times water content applied using a No. 5 coating rod, (b) shows the condition of the coated surface after two coats of the same swollen modified mannan sol as (a), and (c) shows the condition of the coated surface after three coats of the same swollen modified mannan sol as (a). [Figure 13] Scanning microscope photographs of paper coated with swollen modified mannan sol, (a) shows the condition of the coated surface after 300 times swollen modified mannan sol was applied once with a No. 48 coating rod, and (b) shows the condition of the coated surface after 150 times swollen modified mannan sol was applied once with a No. 5 coating rod. [Figure 14] (a) is an optical microscope photograph of the surface of paper that has not been coated with swollen modified mannan sol, and (b) is an optical microscope photograph of the surface of paper that has been coated three times with swollen modified mannan sol at a hydration ratio of 300 times using a No. 5 coating rod. [Figure 15] This is a photograph of a chocolate confectionery being placed on a functional paper product coated with swollen modified mannan sol and observed over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the functional paper product according to the embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows (a) a cross-sectional view of a conventional paper product (i.e., base paper 10 on which no coating is formed) and (b) a cross-sectional view of the functional paper product 1 according to the present embodiment. Fig. 2 shows (a) a cross-sectional view of the conventional paper product and (b) a scanning microscope photograph of the surface of the functional paper product according to the present embodiment.

[0014] The functional paper product 1 according to this embodiment comprises a base paper 20 and a coating 10 formed on the base paper 20 .

[0015] There is no particular limitation on the type of base paper 20, and any paper used for the purpose of imparting water resistance, oil resistance, and durability, such as food base paper, tableware base paper, and cardboard base paper, can be used. In particular, it is preferable to select paper used for manufacturing paper food containers and paper tableware. Examples of food containers include paper cups, paper cups, paper plates, paper trays, ice cream containers, milk containers, liquor containers, soft drink containers, ramen containers, rice bowl containers, and confectionery containers. Examples of tableware include spoons, forks, chopsticks, straws, stirrers, and paper knives. Other paper products include laundry detergent containers, kitchen detergent containers, dressing containers, pickle containers, liquid detergent and cosmetic containers, food container lids, hamburger wrapping paper and hamburger boxes, paper bags, and other wrapping papers.

[0016] The coating 10 is composed primarily of modified mannan in which the acetyl groups of konjac mannan have been released, and is formed when the swollen modified mannan sol, in which the viscosity of the swollen modified mannan before hardening is 3000 mPa·s or less, has hardened while infiltrating into the gaps between the cellulose fibers of the base paper 20.

[0017] As shown in Figure 1 (b), the swollen modified mannan sol hardens while infiltrating into the gaps between the cellulose fibers of the base paper 20, so that the coating 10 and the base paper 20 are firmly bonded together, and no adhesive is required to bond the base paper 20 and the coating 10.

[0018] 1(b) appears to have a two-layer structure in order to explain the relationship between the base paper 20 and the coating 10, but in reality, the swollen modified mannan sol hardens while infiltrating into the gaps between the cellulose fibers of the base paper 20, so the thickness of the coating 10 is almost the same as that of the base paper 20, and there is no clear interface between the base paper 20 and the coating 10. Therefore, the coating 10 can add water resistance, oil resistance, and durability without impeding the original uses and functions of conventional paper products.

[0019] As shown in Figure 2(a), there are many gaps between the cellulose fibers in the base paper 20, so when liquid is poured into the base paper 20, the liquid leaks out through these gaps. In contrast, the functional paper product 1 according to this embodiment is formed so that the gaps between the cellulose fibers of the base paper 20 are covered with a coating 10 as shown in Figure 2(b), so that even when liquid is poured, the liquid is retained without leaking, achieving water resistance and oil resistance. In addition to liquids such as water and oil, solids and gases can also be retained.

[0020] As shown in FIG. 2(b), the coating 10 is preferably formed so as to completely fill the gaps (holes) between the cellulose fibers of the base paper 20, but depending on the use of the functional paper product of this embodiment, it is not necessarily necessary to form a complete coating without gaps (holes). For example, when the functional paper product of this embodiment is used to make plates, knives, forks, spoons, bags, and wrapping paper, these are uses that do not require complete water resistance and oil resistance. The same is true when the product is made into cups, bowls, and beverage packs. This is because when the coating 10 comes into contact with water, it absorbs water and swells, filling the gaps in the base paper. This is due to the fact that the raw material of the coating 10 is konjac mannan.

[0021] Even if the coating 10 absorbs water and swells, due to the inherent irreversibility of konjac, the coating 10 will not dissolve or return to the swollen modified mannan sol before hardening. In addition, the coating 10 has the same strength as a general polyethylene film, and is therefore resistant to high and low temperatures and acids and alkalis.

[0022] The functional paper product according to the present embodiment can be formed into a shape such as a cube, a rectangular parallelepiped, or a triangular pyramid to obtain a beverage pack for containing beverages such as milk. Furthermore, by forming it into a bag shape, it can be used as a paper bag as an alternative to a shopping bag. In addition, the dried paper can be formed into any shape such as a spoon, fork, chopsticks, straw, stirrer, or plate. By forming it into a desired shape in this way, various functional paper products can be obtained. Furthermore, it can be used as a packaging paper for foods such as hamburgers. In addition, since the functional paper product according to the present embodiment is water-resistant and oil-resistant, it can be used for purposes other than the functional paper products exemplified above as long as water-resistant and oil-resistant properties are required.

[0023] An example of a functional paper product other than the functional paper products exemplified above is cardboard. That is, by using cardboard base paper (liner base paper and / or core base paper) for the base paper 20, it is possible to provide cardboard that is more water-resistant, oil-resistant, and durable than general cardboard. Cardboard with such added functionality can be used not only as a packaging material to protect products from scratches, dirt, crushing, etc. as in the past, but also for meat, seafood, vegetables, frozen foods, and the like that could only be used in polystyrene foam containers.

[0024] Furthermore, the paper can be used in functional paper products, such as umbrella fabrics, raincoats, hats, etc.

[0025] Next, a method for producing a functional paper product according to an embodiment of the present invention will be described. The swollen modified mannan sol applied to the functional paper product of the present invention is within the following range. That is, as disclosed in Japanese Patent No. 6089308, water, konjac mannan, and an alkali are mixed and stirred to release acetyl groups, and modified mannan whose swelling is suppressed is used. The swollen modified mannan sol in which the acetyl groups have been released and the pH of the modified mannan is lowered by neutralizing the modified mannan, and the swelling suppression is released is preferably used because the sol from which the acetyl groups have been released has the ability to gel even in the pH range from acidic to weakly alkaline, and does not have the konjac odor, harshness, or astringency.

[0026] However, in addition to the above-mentioned swollen modified mannan sol, any mannan sol that has the ability to gel even under low pH conditions, such as a mannan sol that gels in the acidic to neutral pH range, or a sol in which modified konjac powder that has been deacetylated with an alkali or enzyme is dispersed in water, may be used.

[0027] Next, a method for preparing the swollen modified mannan sol for application to paper products will be described.

[0028] Swollen denatured mannan sol can be obtained by subjecting konjac mannan to alkali treatment and neutralization treatment. Konjac mannan is mixed with water, alkali, and mixed, and the mixture is stirred for 1 to 100 minutes to inhibit swelling, and the acetyl group is released to obtain denatured mannan. The denatured mannan obtained is neutralized to release the swelling, and when the denatured mannan swells, stirring is stopped and the mixture is allowed to swell sufficiently to obtain swollen denatured mannan sol.

[0029] The konjac mannan may be one or a mixture of two or more of ground konjac root, konjac flour, and konjac mannan obtained by washing konjac flour with an alcoholic aqueous solution. The variety of konjac root is not limited, and any variety of konjac genus of the Araceae family that contains konjac mannan may be used.

[0030] The ratio of konjac mannan to the alkaline solution is preferably 10 to 500 parts of water per 1 part of konjac mannan. The water temperature is preferably 60 degrees Celsius or lower.

[0031] The alkali to be added may be strong, and examples include calcium hydroxide, calcined shell calcium, and eggshell calcium. The amount of alkali must be enough to liberate the acetyl groups in the konjac mannan and inhibit swelling, and is greater than the amount of alkali used when producing konjac for normal food use. In the case of calcium hydroxide, it is preferable to use 7.6% or more of the weight of the konjac mannan.

[0032] The pH of the alkaline solution is preferably 11.7 or higher. If the pH is too low, swelling cannot be suppressed. If the pH is too high, swelling suppression may not be released depending on the type and degree of purification.

[0033] Swelling inhibition means suppressing the inherent ability of konjac mannan to swell (speed, viscosity, etc.). For example, when using Japan-produced premium konjac mannan of the KONJAC variety to produce regular konjac for food use, calcium hydroxide is used in an amount of about 3-6% of the weight of the konjac mannan. In comparison, by using a larger amount of calcium hydroxide that slows down the swelling speed or reduces the viscosity, the swelling can be suppressed.

[0034] The acetyl group of konjac mannan is released by alkali treatment, and the swelling-inhibited modified mannan is mixed with water and alkali, and the swelling inhibition is released by using a food or neutralizing agent to swell the mannan, thereby obtaining a swollen modified mannan sol. The food or neutralizing agent used may be any substance that can release the swelling inhibition, and a food or neutralizing agent that lowers the pH is preferred. After addition, the mannan sol swells in a few seconds to 60 minutes when stirred, and a swollen modified mannan sol can be obtained.

[0035] The swollen modified mannan sol thus produced is applied to a base paper and dried. In this case, hot air drying is preferable, but other drying methods such as natural drying and vacuum drying may also be used.

[0036] Next, the dried paper (paper coated with the swollen modified mannan sol and dried) is molded into the shape of the desired paper product, thereby obtaining functional paper products of any shape, such as plates, cups, bowls, boxes, etc., that are water-resistant, oil-resistant, and durable.

[0037] The obtained functional paper product can then be molded into any shape, such as a cube, rectangular parallelepiped, roughly triangular pyramid, or bag, depending on the application. In addition, the dried paper can also be molded into any shape, such as a spoon, fork, chopsticks, straw, or stirrer. By molding into the desired shape in this way, various functional paper products can be obtained. Furthermore, it can also be used as packaging paper for foods such as hamburgers.

[0038] Next, the viscosity adjustment of the swollen modified mannan when the mannan is applied to the base paper will be described.

[0039] When mass-producing functional paper products by coating the swollen modified mannan, it is desirable for the viscosity value to be 3000 mPa·s or less, preferably 1000 mPa·s or less, depending on the specifications of existing manufacturing equipment.

[0040] It is known that the viscosity value of the swollen denatured mannan in the present invention decreases with increasing temperature. Therefore, three types of mannan with mannan concentrations of 1%, 1.2%, and 1.4% were tested in a thermostatic water bath at four temperatures, 28°C, 35°C, 40°C, and 50°C, with a stirring speed of 90 rpm for 5 hours (viscosity value measured every hour). The above viscosity values ​​were measured after 4 hours at 35°C (rotation speed 30 rpm) using a rotor M4 with a viscometer "TVB-10" manufactured by Toki Sangyo Co., Ltd. "TVB-10" viscometer.

[0041] Figures 3 to 5 show the above test results in graphs for each mannan concentration. The test results show that when the mannan concentration is 1%, the viscosity value can be reduced to 3000 mPa·s or less by controlling the temperature in the 40-50°C range. These results also show that in order to further reduce the viscosity value, it is necessary to keep the mannan concentration at 1% or less.

[0042] Therefore, in order to examine mannan concentrations of 1% or less, four hydration ratios were used: 150 times (mannan concentration: 0.66%), 200 times (mannan concentration: 0.5%), 250 times (mannan concentration: 0.4%), and 300 times (mannan concentration: 0.33%). Tests were conducted at 35°C in a thermostatic water bath with a stirring speed of 90 rpm for four hours (viscosity values ​​were measured every hour).

[0043] The test results are shown in Figure 6, which is a graph of the hydration ratio of mannan (the numbers in parentheses are concentrations). The test results show that the viscosity value can be kept below 3000 mPa s at any hydration ratio, and that by increasing the hydration ratio to 200 or more, the viscosity can be kept below approximately 1000 mPa s.

[0044] In addition, Figure 7 shows the viscosity reduction rate depending on the temperature range and stirring time (stirring speed 90 rpm) at a mannan concentration of 1%, obtained from the experimental results. As shown in the table, it is possible to significantly reduce the viscosity value by increasing the temperature. This shows that even when the mannan concentration is 1%, 1.2%, or 1.4%, it is possible to reduce the viscosity value of the swollen modified mannan sol to 3000 mPa s or less, or even 1000 mPa s or less, by increasing the temperature and adjusting the stirring time.

[0045] As mentioned above, the viscosity value can be reduced by reducing the mannan concentration to 1% or less, but reducing the mannan concentration leads to a reduction in the amount of mannan fiber contained in the mannan. This can affect the film thickness of the swollen modified mannan sol when it is applied to the base paper and dried, and the penetration of water and oil into the cellulose fiber structure of the base paper, which may affect the water and oil resistance.

[0046] Therefore, we estimated the mannan fiber content for each hydration ratio, and actually applied it to base paper and conducted a 24-hour verification test to verify the water and oil resistance, including bleeding to the back side of the paper.

[0047] The swollen modified mannan sol used in the verification was produced as follows. Konjac mannan produced in Japan, the variety of which is KONJAC, and calcium hydroxide were added to 100 cc of water at 12°C, and the mixture was stirred for 10 minutes. Then, 0.15 g of citric acid, a neutralizing agent, was added, and when the mixture swelled, the stirring was stopped and the mixture was left for 60 to 120 minutes to produce a swollen modified mannan sol. The swollen modified mannan sol produced was then applied to a base paper and dried. Note that, when producing a neutral swollen modified mannan sol, citric acid was added as a neutralizing agent, but when producing an acidic swollen modified mannan sol, a slightly larger amount of citric acid was added. Note that, instead of citric acid, other acidic substances or foods containing acids that can be used as neutralizing agents may be used.

[0048] To confirm the water resistance, a water absorption test was performed using a water absorption tester. The water absorption tester used was a Garle Cobb Size Tester (standard type) manufactured by Kumagai Riki Kogyo Co., Ltd. And the test paper used was a base paper for food containers. When applying the swollen modified mannan sol to the base paper, coating rods No. 5 and No. 48 manufactured by Kumagai Riki Kogyo Co., Ltd. were used to apply the swollen modified mannan sol to 11.43 μm (for No. 5) and 109.8 μm (for No. 48), respectively.

[0049] In the 24-hour verification test using the Garle Cobb Size Tester, tea beverages were used as samples to confirm water resistance, and coffee beverages and household cooking oil were used as samples to confirm oil resistance. In addition, chocolate was directly contacted (for approximately 8 months) to confirm the resistance.

[0050] The results of the verification are shown in the table in Figure 8. As shown in the table, looking at the relationship between mannan content and water / oil resistance, it is clear that the lower limit is approximately 0.26g of mannan per 100cc, with 0.5g or more being preferable whenever possible. This means that it is possible to adjust the mannan content depending on the production cost and application (required strength of water / oil resistance).

[0051] In addition, looking at the relationship between the thickness of the applied swollen modified mannan sol before hardening and the water and oil resistance, the lower limit of the thickness of the film before hardening is about 3 μm, depending on the content of swollen modified mannan sol, and it is preferable to make it 5 μm or more if possible. As shown in the table, in the case of household edible oil, the oil resistance is improved by applying swollen modified mannan sol multiple times to increase the film thickness. This makes it possible to adjust the film thickness before hardening depending on the manufacturing cost and application (required strength of water and oil resistance).

[0052] Regarding water resistance, it is possible to solve the cost problem by changing the hydration ratio and the film thickness before hardening depending on the purpose and conditions of use of the paper product to be used. For example, when manufacturing a paper tray coated with swollen modified mannan sol instead of a PVC food tray of a general mass retailer, if the moisture content of the food is low, it is possible to manufacture it more cheaply than a PVC food tray by setting the hydration ratio to about 500 times and the film thickness before hardening to about 3 μm. Conversely, if the moisture content of the food is high, it is possible to prevent moisture from seeping in by applying swollen modified mannan sol to the front and back of the tray, for example.

[0053] For paper cups, water resistance can be ensured by applying swollen modified mannan sol to the inside of the surface that comes into contact with water under normal conditions of use, but for example, when used for a long time with ice such as iced coffee, applying swollen modified mannan sol to the front and back of the paper cup can provide performance equivalent to that of a PVC cup. Of course, it is also possible to obtain performance equivalent to that of a PVC cup lid by applying swollen modified mannan sol to the front and back of a paper cup lid.

[0054] Based on the results of the above-mentioned verification, a verification was also conducted on the case where chocolate was directly contacted (continuous contact for about 8 months) as shown in FIG. 14. In the illustrated example, a mannan aqueous solution with a water addition ratio of 250 times and a very small amount of mannan dietary fiber was used, and a very small amount of application (0.11 g / m 2 ), no oil was observed to penetrate into the contact surface or back side of the swollen modified mannansol-coated paper. Therefore, it was confirmed that the paper exhibits the same level of oil resistance as PVC-processed packaging materials, and it can be used as a packaging material for chocolate products in the same way as PVC-processed packaging materials and aluminum packaging materials.

[0055] Next, the surface treatment of paper coated with swollen modified mannan sol can make a big difference in water and oil resistance. This is influenced by the properties of mannan. For example, when swollen modified mannan sol is applied to copy paper used in general jet printers and a water and oil resistance test is performed, the water and oil resistance tends to be lower than that of general paper with an untreated surface. The same tendency is seen in paper with a water-resistant surface.

[0056] Therefore, we used base papers with different smoothness and actually applied swollen modified mannan sol with coating rods No. 5 and No. 48 to confirm the results. As a result of the confirmation, as shown in Figure 9, it was found that when increasing the film thickness, the lower the smoothness of the base paper, the thicker the film can be made, and it is preferable for the base paper to have a lower smoothness. In other words, making the smoothness of the base paper as low as possible and applying swollen modified mannan sol to the unprocessed surface leads to improved water and oil resistance. Also, even if swollen modified mannan sol is applied to paper that has been treated to be water resistant with chemicals, etc., the film thickness cannot be sufficiently secured, so water and oil resistance does not improve.

[0057] Next, we developed a functional paper product, hamburger wrapping paper (45g / m 2 The results of a water resistance test conducted by applying swollen modified mannan sol at a water addition ratio of 100 to 500 times to a hamburger wrapping paper base paper are described below. That is, in the water resistance test, a box-shaped container (7.5 cm x 8 cm, depth 3.8 cm) was created by applying swollen modified mannan sol to a hamburger wrapping paper base paper using coating rods No. 5 and No. 48, and about 40 cc of room temperature tea was poured into the box-shaped container, and the time elapsed until water leakage was confirmed was investigated.

[0058] As the results of the water resistance test, Fig. 10 shows the test results of a hamburger wrapping paper coated with modified mannan sol swollen by coating rod No. 5, and Fig. 10 shows the test results of a hamburger wrapping paper coated with modified mannan sol swollen by coating rod No. 48. Figs. 10 and 11 show the estimated mannan fiber amount together with each water addition ratio.

[0059] In addition, in the above water resistance test, a water resistance test was conducted on a hamburger wrapping paper base paper that was not coated with swollen modified mannan sol as a comparison, and water leakage from the box-shaped container was confirmed in 4 minutes and 15 seconds. On the other hand, it can be seen that the hamburger wrapping paper coated with the modified mannan sol swollen by coating rod No. 5 exhibits water resistance of 1.5 hours (hours) even at a hydration ratio of 500 times, and 11.3 hours (hours) at a hydration ratio of 100 times. It can also be seen that the hamburger wrapping paper coated with the modified mannan sol swollen by coating rod No. 48 exhibits water resistance of 2.5 hours (hours) even at a hydration ratio of 500 times, and 23.8 hours (hours) at a hydration ratio of 100 times.

[0060] From the above water resistance test results, it is possible to significantly improve water resistance by setting the hydration ratio at least to 500 times or less. It is more preferable to set the hydration ratio to 400 times or less, and even more preferable to set the hydration ratio to 300 times or less, which can ensure water resistance for more than half a day and makes it possible to significantly improve water resistance.

[0061] As can be seen from the amount of mannan fiber shown in the water resistance test results shown in FIG. 10, the amount of mannan fiber is at least 0.01 g / m 2 More than 0.017 g / m 2 By applying the above amount of mannan fiber to the base paper, it is possible to significantly improve the water resistance.

[0062] Next, we investigated the effect of applying the swollen modified mannan sol on the durability of the base paper. Conventionally, the final product is manufactured by increasing the thickness of the base paper depending on the required durability of the paper product. However, this increases the amount of base paper used, which leads to increased costs and environmental impact.

[0063] In this verification, the swollen modified mannan sol was applied to copy paper, and the burst strength was measured using a KRK burst strength tester manufactured by Kumagai Riki Kogyo Co., Ltd., and the durability (tensile strength, etc.) was measured using a horizontal tensile tester (desktop type). The burst strength test results showed that when the swollen modified mannan sol was applied to one side, the burst strength was improved by 140.6% compared to uncoated paper, and when the swollen modified mannan sol was applied to both sides, the burst strength was improved by 158.1% compared to uncoated paper. In terms of tensile strength, when the swollen modified mannan sol was applied to one side, the longitudinal breaking length was improved by 110.1% compared to uncoated paper, and the transverse breaking length was improved by 110.9%.

[0064] Cardboard boxes and paper containers, etc., can be damaged from the outside when stacked or during transportation, but the above-mentioned verification results show that in order to ensure the required burst strength and tensile strength, by applying swollen modified mannan sol to one side or both sides of the paper as necessary, it is possible to improve the durability of paper products without increasing the thickness of the base paper or the amount of base paper used, as in the past.

[0065] In other words, in the case of cardboard, by applying the swollen modified mannan sol to one side, it is possible to ensure water resistance and improve burst strength and tensile strength. This also makes it possible to reduce the thickness of the cardboard base paper (liner paper) that is conventionally used, thereby reducing costs. Of course, by applying the swollen modified mannan sol to both sides of the cardboard base paper as necessary, it is possible to further increase the burst strength and tensile strength. In addition, the same effect can be obtained by applying the swollen modified mannan sol to the core base paper, which is necessary for the strength of the cardboard.

[0066] Table 1 shows the results of examining the breaking strength, burst index, tensile strength, and breaking length, which are indicators of durability, of functional paper products manufactured by forming a coating 20 on the surface of liner paper, using liner paper as base paper 10.

[0067] The liner paper used was LB-grade liner paper according to the JIS standard (JISP3902). The swollen modified mannan sol was applied once with a coating rod of No. 5 or No. 48, with a water addition ratio of 150 (mannan concentration of 0.66%). The test conditions were temperature 22.6°C, humidity 38%, test machine type C (kPa), and span 100 mm.

[0068] As shown in Table 1, the liners (samples 1 and 2) on which a coating of swollen modified mannan was formed showed significantly improved burst strength, burst index, tensile strength, and breaking length compared to the base paper. From these results, it became clear that by forming a coating made by hardening the swollen modified mannan sol, the quality of the cardboard can be improved without increasing the thickness of the paper. In addition, since the formed coating has a high frictional force, forming the coating also increases the frictional resistance of the cardboard, making the friction treatment of the cardboard, which is commonly performed, unnecessary. Although data is not shown, functional paper products in which a coating 20 is formed on the liner base paper are also imparted with water resistance and oil resistance.

[0069] [Table 1]

[0070] Table 2 shows the results of investigating the burst strength, longitudinal strength (tensile strength and elongation), and transverse strength (tensile strength and elongation), which are indicators of the durability of the core raw paper, produced from a functional paper product in which a coating 20 is formed on the surface of the core raw paper, using the core raw paper as base paper 10. The measuring equipment and conditions were the same as those for the liner paper described above.

[0071] The core raw paper used was MB-class core raw paper according to the JIS standard (JISP3902). The coating conditions for the swollen modified mannan sol were as follows: the swollen modified mannan sol with a water addition ratio of 150 (mannan concentration 0.66%) was applied once using a No. 5 or No. 48 coating rod.

[0072] As shown in Table 2, the liners (samples 3 and 4) on which a coating of swollen modified mannan was formed had burst strength, longitudinal strength, and transverse strength equal to or greater than those of the core raw paper. This result demonstrated that the durability of the core raw paper can be improved by forming a coating of hardened swollen modified mannan sol on the core raw paper. The core is used to impart strength to cardboard, but the core of this embodiment can add strength to the cardboard without increasing the weight of the core. Although no data is shown, functional paper products in which a coating 20 is formed on the core raw paper are also imparted with water resistance and oil resistance.

[0073] [Table 2]

[0074] (Verification by microscopic photograph) Next, the following will be explained based on micrographs of the surface coated with swollen modified mannan sol. Figure 12 shows scanning micrographs of paper coated with swollen modified mannan sol, in which (a) shows the condition of the surface coated with swollen modified mannan sol at a water addition ratio of 300 times, which was coated once with a No. 5 coating rod, (b) shows the condition of the surface coated with the same swollen modified mannan sol as (a) coated twice, and (c) shows the condition of the surface coated with the same swollen modified mannan sol as (a) coated three times.

[0075] As shown in Figure 12(a), it can be seen that a film of swollen modified mannan sol is formed in the gaps between the cellulose fibers of the paper, but there are some cavities that appear black here and there. Furthermore, as shown in Figure 11(b), when the swollen modified mannan sol is applied twice, a film of the swollen modified mannan sol is formed in the gaps between the cellulose fibers more effectively, and the number of cavities is significantly reduced. Furthermore, as shown in Figure 12(c), when the swollen modified mannan sol is applied three times, almost no cavities are found, and it can be seen that a film of the swollen modified mannan sol is reliably formed over a wide area.

[0076] That is, by increasing the number of times of application of the swollen modified mannan sol, a film of the swollen modified mannan sol is evenly formed on the surface of the paper, and it can be confirmed that the mannan fibers penetrate into the gaps between the cellulose fibers of the base paper. This contributes greatly to the water resistance and oil resistance of functional paper products. Note that base paper whose surface has been treated with anti-bleeding agents or chemicals for water resistance processing is not preferable because it inhibits the formation of the mannan film as described above.

[0077] Next, FIG. 13(a) shows a scanning microscope photograph of a coating surface where swollen modified mannan sol with a hydration ratio of 300 times was applied once with a No. 48 coating rod, and FIG. 13(b) shows a scanning microscope photograph of a coating surface where swollen modified mannan sol with a hydration ratio of 150 times was applied once with a No. 5 coating rod. Comparing these, it can be seen that there are fewer remaining gaps in FIG. 13(a) than in FIG. 13(b). Therefore, even if the hydration ratio is increased, by increasing the film thickness of the swollen modified mannan sol, it is possible to more reliably form a film of the swollen modified mannan sol on the surface of the base paper.

[0078] In addition, Fig. 14(a) shows an optical microscope photograph of the surface of base paper not coated with swollen modified mannan sol, and Fig. 14(b) shows an optical microscope photograph of the coated surface of a paper surface coated with swollen modified mannan sol at a hydration ratio of 300 times three times using a No. 5 coating rod. As shown in the figure, the surface not coated with swollen modified mannan sol has light diffusely reflected by the cellulose fibers of the base paper, making the outlines of the cellulose fibers vague and dark overall. On the other hand, the surface coated with swollen modified mannan sol three times and forming a film of swollen modified mannan sol all over has an iridescent film and clearly visible outlines of the cellulose fibers, making it bright overall.

[0079] (Follow-up observation of foods containing fats and oils) Figure 15 shows a photograph of a chocolate confectionery placed on a functional paper product coated with swollen modified mannan sol and observed over time. The example shown in the photograph is one with a water content of 250 times, but no oil seepage was observed over a period of eight months.

[0080] (Other embodiments) Although several embodiments of the functional paper product of the present invention have been described above, the present invention is not necessarily limited to the above-mentioned embodiments, and the following are possible.

[0081] For example, the above-mentioned verification results were mainly focused on swollen modified mannan sol with a hydration ratio of 100 to 500 times, but the range is not necessarily limited to this. For example, the hydration ratio can be set to 500 to 3000 times, and verification has made it clear that water resistance and oil resistance can be ensured even in this range. Within this range of hydration ratio, the viscosity becomes very low, making it easy to apply using general-purpose machines.

[0082] On the other hand, when the hydration ratio is 500 to 3000 times, the concentration of the swollen modified mannan sol decreases, so it is necessary to satisfy the required performance by increasing the number of applications depending on the water resistance and oil resistance required for the functional paper product. Therefore, from the viewpoint of using the existing facilities of paper companies, printing companies, etc. and efficiently mass-producing high-quality functional paper products, it can be said that a hydration ratio of 100 to 500 times is a preferable range. [Industrial Applicability]

[0083] The present invention makes it possible to mass-produce functional paper products that are water-resistant and oil-resistant while suppressing the generation of konjac odor, harshness, astringency, etc., efficiently and inexpensively using the existing facilities of paper companies, printing companies, etc., without the need to install new coating equipment. [Explanation of symbols]

[0084] 1...Functional paper product according to this embodiment 10… membrane 20…base paper

Claims

1. A functional paper product comprising a base paper and a coating formed on the base paper, The coating is mainly composed of modified mannan in which the acetyl group of konjac mannan is released, The swollen modified mannan sol, in which the viscosity of the swollen modified mannan before hardening is 3000 mPa·s or less, is hardened in a state in which it is infiltrated into the gaps between the cellulose fibers of the base paper. Functional paper products.

2. 2. The functional paper product according to claim 1, wherein the viscosity of the swollen modified mannan sol before hardening is 1000 mPa·s or less.

3. The amount of mannan fiber in the swollen modified mannan sol is 0.01 g / m ２ The functional paper product according to claim 1 or 2.

4. 2. The functional paper product according to claim 1, wherein the base paper is at least one selected from the group consisting of base paper for food containers, base paper for tableware, and base paper for cardboard.

5. The functional paper product according to claim 1, which is at least one selected from the group consisting of paper cups, paper cups, paper plates, paper trays, ice cream containers, milk containers, liquor containers, soft drink containers, ramen containers, rice bowl containers, confectionery containers, paper bags, spoons, forks, chopsticks, straws, stirrers, paper knives, laundry detergent containers, kitchen detergent containers, dressing containers, pickle containers, liquid detergent and cosmetic containers, food container lids, hamburger wrapping paper and hamburger boxes, paper bags, wrapping paper, and cardboard.

6. The functional paper product according to claim 1, which is at least one selected from the group consisting of an umbrella, a raincoat, and a hat.

Images