Food containers and paper products

Abstract

The object is to provide a food container and paper product that are water-resistant, oil-resistant and recyclable. A food container, wherein a modified mannan whose swelling is suppressed by releasing acetyl groups is mixed and stirred with water, konjac mannan and an alkali, and a neutral or acidic modified mannan is solified or gelled to remove the swelling suppression of the modified mannan by neutralization, and the solified mannan sol or gelled mannan gel is applied to a paper food container and dried.

Description

Technical Field

[0001] The present invention relates to food containers and paper products which are water-resistant, oil-resistant and recyclable. Background Art

[0002] Currently, plastic food containers, straws, etc. are used in various occasions. They are highly convenient because they are excellent in water resistance and oil resistance and can handle a variety of foods and beverages. On the other hand, plastic food containers and straws have environmental issues related to their disposal.

[0003] For example, in the United States, plastic waste has been buried in the soil until now. However, since most plastic waste does not decompose naturally, it accumulates in the soil. On the other hand, in developing countries, plastic waste is increasingly being dumped directly into rivers and oceans, causing significant adverse effects on the marine ecosystem.

[0004] As such environmental issues are pointed out, there is a growing trend to abolish the use of plastic food containers worldwide. For example, world-famous coffee chains and fast food restaurants aim to abolish the use of plastic straws. In addition, a family restaurant in Japan has abolished the use of plastic straws in principle and switched to alternative straws made of naturally degradable plastic materials and food materials, and is actively developing food containers made of food materials.

[0005] As an alternative to conventional plastic straws and food containers, there is a method of using naturally degradable plastic materials and food materials. However, although the environmental load is reduced, the manufacturing unit price is significantly higher than before.

[0006] There is also a method of laminating paper containers with polyethylene films, but this method not only greatly increases the manufacturing unit price compared to the past, but also cannot be recycled due to the lamination process even though it is a paper product. Therefore, the laminated paper containers have to be incinerated, which has a heavy environmental impact.

[0007] As such, in the method of using a biodegradable plastic raw material or food raw material that is considered to be an alternative to plastic food containers and straws, there is a problem that the manufacturing unit price is high. In addition, in the case of a method of laminating a paper container, in addition to the high manufacturing unit price, there is also an environmental problem that recycling is impossible.

[0008] Therefore, as a relatively cheap countermeasure, it is considered to apply the konjac paste known to have water resistance on the paper, or to use konjac film, konjac lamination, etc. And, as a technology of sticking konjac film on a paper container, there is the technology described in the following Patent Document 1.

[0009] Furthermore, the following Non-Patent Document 1 describes the use of konjac paste as an adhesive for laminating Japanese paper.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Publication No. 2002-355918

[0013] Non-patent literature

[0014] Non-patent document 1: Dynic Co., Ltd., "まるふのproduction", [online], Internet<URL:https: / / www.dynic.co.jp / company / 80 / chno3 / ch03-3.html.> Summary of the invention

[0015] Problem that the invention aims to solve

[0016] The technology described in Patent Document 1 is a technology of pasting deacetylated konjac membranes on paper. Thus, water-resistant paper can be produced at low cost. However, the deacetylated konjac membranes themselves have alkalinity, so when the paper products produced by the technology described in Patent Document 1 are used in food containers, konjac smell, bitterness, astringency, etc. are generated. Therefore, the paper products using the technology described in Patent Document 1 cannot be used in food containers, etc.

[0017] In addition, in Non-Patent Document 1, since konjac paste is used directly as an adhesive, the konjac smell is strong. Therefore, similarly to Patent Document 1, it cannot be used as a food container or paper product.

[0018] Solutions for solving problems

[0019] In view of the above problems, the inventors of the present invention have invented a food container and a paper product which are water-resistant and oil-resistant and can be recycled.

[0020] The first invention is a food container, wherein a neutral or acidic mannan sol obtained by neutralizing a modified mannan in which acetyl groups are released and swelling is suppressed by mixing and stirring water, konjac mannan and an alkali, or a mannan gel obtained by gelling the mannan sol is applied to a paper food container and dried.

[0021] By using the food container of the present invention, it is possible to obtain a food container that suppresses the occurrence of konjac odor, bitterness, astringency, etc. and has water resistance. In addition, unlike food containers that have been laminated, the food container of the present invention can be naturally decomposed, so the environmental load is lower than before, and it can be manufactured at a low cost. In addition, since it dissociates in water, it can also be recycled.

[0022] In the above invention, the food container may be formed by applying the solubilized mannan sol or the gelled mannan gel to a thickness of at least 50 μm and then drying it.

[0023] In order to ensure water resistance as a food container for storing mineral water or the like, it is preferred to apply the coating in a thickness of 50 μm or more as in the present invention.

[0024] In the above invention, the food container may be formed by applying the solubilized mannan sol or the gelled mannan gel to a thickness of at least 100 μm and then drying it.

[0025] Coating with a thickness of 100 μm or more as in the present invention is more preferred because it increases the variety of beverages that can be contained.

[0026] In the above invention, the food container may be a food container in which the solubilized mannan sol or the gelled mannan gel is applied to a thickness of at least 200 μm and then dried.

[0027] By applying the coating at a thickness of 200 μm or more, oil resistance can be ensured in addition to water resistance.

[0028] The fifth invention is a paper product, wherein a neutral or acidic mannan sol obtained by neutralizing and releasing the swelling inhibition of the modified mannan, or a mannan gel obtained by gelling the mannan sol, is applied to paper and dried.

[0029] Containers that require water resistance and oil resistance are not limited to food containers, but can also be widely used in paper products.

[0030] In the above invention, the paper product can be configured as a paper product for food.

[0031] The present invention is particularly effective in that it does not produce konjac smell, bitterness, astringency, etc., and has water resistance and oil resistance, and can be recycled. Therefore, it is particularly preferred as a paper product for food use.

[0032] In the above invention, the paper product may be configured as any one or more paper products including a spoon, a fork, chopsticks, a straw, a stirring stick, a bag, a beverage package, and a food packaging paper.

[0033] As an example of a paper product for food use, the product of the present invention can be mentioned.

[0034] Effects of the Invention

[0035] According to the present invention, it is possible to produce a food container or paper product that suppresses the generation of konjac smell, bitterness, astringency, etc. and has water resistance and oil resistance. In addition, the food container or paper product in the present invention can be naturally decomposed, so the environmental load is lower than before, and it can be manufactured at a low cost. In addition, the food container or paper product in the present invention dissociates in water and can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a table showing the results of the water absorption test.

[0037] Figure 2 This is a table showing the results of a water absorption test for confirming the presence or absence of influence by high temperature or low temperature.

[0038] Figure 3 It is a table showing the results of the sensory test.

[0039] Figure 4 This is a photograph showing the state of the torn test paper after it was placed in a container of water and left for 24 hours in a recyclability confirmation test.

[0040] Figure 5 This is a photograph showing a state where a test paper immersed in water for 24 hours is put into a pulp disintegrator.

[0041] Figure 6 This is a photograph showing the disintegrated state of the test paper.

[0042] Figure 7 This is a photograph showing a state in which a mixed solution obtained by mixing water and a test paper is fed into a sheet making machine.

[0043] Figure 8 This is a photograph showing the state of paper after being made by a sheet making machine.

[0044] Fig. 9 This is a photograph showing a state where copied paper is fixed on a press.

[0045] Fig.10 This is a photograph showing the state of being put into a dryer after pressing.

[0046] Fig.11 This is a photograph showing the state of recycled paper being discharged from a dryer. DETAILED DESCRIPTION

[0047] As the mannan sol or mannan gel (konjac sol or konjac gel) to be applied to the food container or paper product of the present invention, a mannan sol of modified mannan produced by the production method disclosed in Japanese Patent No. 6089308 is used. The sol from which acetyl groups are released has the ability to gel even in an acidic to neutral pH range and has no konjac smell, bitterness, or astringency, and is therefore preferably used. However, the present invention is not limited thereto, and any substance may be used as long as it is a mannan sol that gels in an acidic to neutral pH range or a mannan gel that is gelled from a mannan sol.

[0048] A method for producing mannan sol or mannan gel (konjac sol or konjac gel) by using modified mannan for coating on food containers or paper products is described.

[0049] Mannan sol is obtained by subjecting konjac mannan to alkali treatment and neutralization treatment. Water, alkali and konjac mannan are mixed and stirred for about 1 to 100 minutes while suppressing swelling to free acetyl groups. Swelling is eliminated by neutralization treatment, and stirring is stopped when mannan swells. Then, mannan sol is obtained by allowing it to swell fully.

[0050] The mannan gel is obtained by heating the mannan sol.

[0051] Konjac mannan can be obtained by mixing one or more of the following: a material obtained by grinding konjac yam, konjac flour, and glucomannan obtained by washing konjac flour with an alcohol aqueous solution. In addition, there is no specific variety of konjac yam, and any variety of the genus Amorphophallus of the Araceae family containing konjac mannan can be used.

[0052] The ratio of konjac mannan to alkaline solution is preferably 10 to 200 parts of water per 1 part of konjac mannan. The water temperature is preferably 60 degrees Celsius or lower.

[0053] The added alkali only needs to be strongly alkaline, and calcium hydroxide, shell-fired calcium, eggshell calcium, etc. can be cited as an example. The amount of alkali needs to be an amount that can free the acetyl group of konjac mannan and inhibit swelling, which is more than the amount of alkali used when manufacturing ordinary konjac. In the case of calcium hydroxide, it is preferably 7.6% or more of the weight of konjac mannan. The pH of the alkaline solution is preferably above 11.7. When the pH is too low, swelling cannot be inhibited. Depending on the variety and degree of purification, when the pH is too high, swelling inhibition may not be lifted. Swelling inhibition refers to inhibiting the ability (speed, viscosity, etc.) of konjac mannan to swell. For example, when using special konjac mannan produced in Japan of the variety KONJAC to manufacture ordinary konjac, calcium hydroxide is used in an amount of about 3% to 6% of the weight of konjac mannan, but compared with this, by using calcium hydroxide in an amount that slows down the swelling rate or lowers the viscosity, its swelling can be inhibited.

[0054] The acetyl group of konjac mannan is freed by alkali treatment, and a food is used in a mixed solution of water and alkali mixed with modified mannan whose swelling is suppressed to remove the swelling inhibition, thereby causing it to swell and obtain a mannan sol. The food used can be any material as long as it removes the swelling inhibition, and a food that lowers the pH is preferred. After addition, when stirring is performed, it swells within a few seconds to 60 minutes to obtain a mannan sol.

[0055] In the case of producing the mannan gel, it is sufficient to heat the mannan sol.

[0056] The mannan sol or mannan gel produced as described above is applied to paper and dried. In this case, hot air drying is preferred, but other drying methods such as natural drying and vacuum drying may also be used.

[0057] Then, the dried paper (paper coated with mannan sol or mannan gel using modified mannan and dried) is formed into the shape of the desired food container. Thus, it is possible to obtain a food container with water resistance and oil resistance in any shape such as a plate, a cup, a bowl, a box, etc. In addition, by forming it into a cube, a rectangular parallelepiped, a roughly triangular pyramid, etc., a beverage package for storing beverages such as milk can be obtained. Furthermore, by forming it into a bag shape, it can be used as a paper bag to replace a shopping bag. In addition, the dried paper can also be formed into any shape such as a spoon, a fork, chopsticks, a straw, a stirring rod, etc. By forming it into a desired shape, various paper products for food can be obtained. Furthermore, it can also be used as packaging paper for foods such as hamburgers. It should be noted that the paper coated with mannan sol or mannan gel manufactured by the above method has water resistance and oil resistance, so as long as the purpose of water resistance and oil resistance is required, it can also be used for purposes other than food containers.

[0058] Next, the mannan sol or mannan gel using the modified mannan was applied to paper at a dilution ratio of 100 times with water to confirm whether the paper had water resistance and oil resistance.

[0059] Regarding the mannan sol using the modified mannan used herein, 0.91 g of Japanese konjac mannan of the KONJAC variety and 0.09 g of calcium hydroxide are added to 100 cc of water at 12°C, and the mixture is stirred for 10 minutes. Thereafter, 0.15 g of citric acid as a neutralizing agent is added, stirring is stopped when swelling occurs, and then the mixture is left for 60 to 120 minutes to prepare a mannan sol. Then, the prepared mannan sol is applied on paper and dried. It should be noted that, in the case of preparing a neutral mannan sol, 0.15 g of citric acid is added as a neutralizing agent, but in the case of preparing an acidic mannan sol, 0.25 g of citric acid is added.

[0060] When confirming the water resistance, a water absorption test using a water absorption tester was performed. The water absorption tester used was a Gurley type Cobb size tester (standard type) manufactured by Kumagai Riki Industry Co., Ltd. In addition, as the test paper, base paper and paper obtained by coating the base paper with a mannan sol adjusted to neutral (about pH 7.0) or acidic (about pH 4.5) and drying it were used. In addition, when the mannan sol was coated on the base paper, it was coated with a No. 22 or No. 44 coating rod manufactured by Kumagai Riki Industry Co., Ltd. to a thickness of 50.3 μm (in the case of No. 22) or 100.6 μm (in the case of No. 44). In addition, a test paper was used in which the paper was coated once with a No. 44 coating rod and dried naturally, and then coated once again with a No. 44 coating rod and dried naturally twice (200.12 μm = 100.6 μm × 2 times of coating).

[0061] The above-mentioned test papers were placed on a water absorption tester and were allowed to contact with the sample liquids for 24 hours. After 24 hours, the presence or absence of leaching to the back side of the test paper was confirmed to confirm water resistance and oil resistance.

[0062] As liquid samples, mineral water (pH 7.0), coffee beverage (pH 3.70), 100% orange juice (pH 3.46), household oil (pH 6.5), Japanese sake (pH 3.71), and cola (pH 2.20) were used.

[0063] As a result, it becomes Figure 1 The results are shown in the table. Figure 1As can be seen from the table, when a mannan sol using modified mannan is coated on base paper with a thickness of about 50 μm or more and dried naturally, a coating film that ensures water resistance is formed, thereby obtaining water resistance. In addition, when a mannan sol using modified mannan is coated on base paper with a thickness of about 100 μm or more and dried naturally, water resistance can be obtained in most cases. Furthermore, when a mannan sol using modified mannan is coated on base paper with a thickness of about 200 μm or more and dried naturally, oil resistance can be ensured in addition to water resistance.

[0064] In addition, in order to confirm whether there is any influence of high temperature or cold temperature, 98 degree hot coffee beverage, 98 degree hot tea, vanilla ice, and room temperature tea were used as samples to confirm the water resistance and oil resistance in the same way. Figure 2 The results are shown in the table.

[0065] according to Figure 2 Even in this case, if a mannan sol using modified mannan is applied to a thickness of about 50 μm or more and dried naturally, water resistance can be obtained, and if a mannan sol using modified mannan is applied to a thickness of 100 μm or more and dried naturally, water resistance can be obtained in most cases.

[0066] Furthermore, a sensory test was conducted to confirm whether konjac smell, bitterness, astringency, etc., were reflected in food, etc. by coating the modified mannan sol on the base paper. In the sensory test, mineral water was placed in three types of food containers: a paper food container coated with a modified mannan sol adjusted to neutral (pH 7.0) and naturally dried for 3 days, a paper food container coated with a modified mannan sol adjusted to acidic (pH 4.09) and naturally dried for 3 days, and a paper food container without any coating. The sensory test collaborators confirmed whether the astringency, bitterness, odor, and taste changed. The sensory test collaborators were 12 women (1 in their 20s, 6 in their 30s, 2 in their 40s, and 3 in their 50s) and 3 men (1 in their 20s and 2 in their 30s).

[0067] The results of the sensory tests are shown in Figure 3 According to the table. Figure 3 As shown in the table, 80% of the sensory test collaborators answered that there was no difference from mineral water in the food containers coated with the mannan sol adjusted to neutral modified mannan and dried, and the effect was small compared with the paper food containers without any coating (about 67%). In addition, about 53% of the sensory test collaborators answered that there was no difference from mineral water in the food containers coated with the mannan sol adjusted to acid modified mannan and dried.

[0068] Therefore, it was found that the generation of konjac smell, bitterness, astringency and the like was suppressed, and in particular, when a neutral modified mannan was used, a higher effect was achieved than when nothing was applied.

[0069] Furthermore, a test was conducted to confirm whether the paper (test paper) coated with the mannan sol using the modified mannan can be recycled. In this test, 10 sheets of ordinary copy paper and thick paper (280 mg / m 2 ) were coated on one side of each sheet with a coating rod No. 22 using a mannan sol using a modified mannan adjusted to a neutral pH of 7.0 at a thickness of 50.3 μm.

[0070] Then, tear the test papers by hand and put them into a container filled with water for 24 hours. Figure 4 Here, copy paper and thick paper as test paper are mixed and put into one container, which reproduces the situation in which various papers are mixed and put into one container filled with water in actual recycling.

[0071] The test paper immersed in water for 24 hours was taken out from the container and gently squeezed. Then, 50 g of the test paper (immersed in water in a torn state) was put into a pulp disintegrator together with 2 L of water and disintegrated for 3 minutes. Figure 5 The state of being put into the pulp disintegrator is shown. As the pulp disintegrator, a standard pulp disintegrator (with a continuously variable transmission) "KRK2530" manufactured by Kumagai Riki Kogyo Co., Ltd. was used.

[0072] The test paper was put into the disintegrator, and the test paper was disintegrated in 2 L of water. Then, 3 L of water was further put into the liquid after the test paper was disintegrated in water. Figure 6 In this way, 1 L of the liquid was taken out from the liquid mixed with the test paper dissociated in 5 L of water and put into the square sheet making machine. Figure 7 As the sheet copying machine, a square sheet copying machine "KRK2555" manufactured by Kumagai Riki Kogyo Co., Ltd. was used. Figure 8 The state after papermaking by a sheet making machine is shown.

[0073] Then, the copied paper is fixed on a press and put into a dryer. Fig. 9 The copied paper is fixed on the press. Fig.10 The state of being put into the dryer after pressing is shown in FIG. As the press machine, a square sheet press "KRK2570" manufactured by Kumagai Riki Kogyo Co., Ltd. is used. In addition, as the dryer, a rotary dryer "KRK2575" manufactured by Kumagai Riki Kogyo Co., Ltd. is used.

[0074] The recycled paper (recycled paper) is discharged from the dryer in Fig.11 The recycled paper (recycled paper) was weighed and found to weigh 3.9 g per sheet.

[0075] From the above results, it was confirmed that even when the mannan sol using modified mannan was applied to paper, it could be sufficiently recycled.

[0076] Industrial Applicability

[0077] According to the present invention, it is possible to produce a food container or paper product that suppresses the generation of konjac smell, bitterness, astringency, etc. and has water resistance and oil resistance. In addition, the food container or paper product in the present invention can be naturally decomposed, so the environmental load is lower than before, and it can be manufactured at a low cost. In addition, the food container or paper product in the present invention dissociates in water and can be recycled.

Claims

1. A paper product, characterized in that: The invention is a paper product comprising base paper and a coating formed on the base paper. The coating is obtained by applying a neutral or acidic mannan sol obtained by neutralizing a modified mannan in which acetyl groups are released and swelling is suppressed by mixing water, konjac mannan and an alkali and stirring the mixture to release the swelling suppression of the modified mannan, and drying the mixture.

2. The paper product according to claim 1, characterized in that The coating is obtained by applying the mannan sol to a thickness of 50 μm or more and drying it.

3. The paper product according to claim 1, characterized in that: The coating is obtained by applying the mannan sol to a thickness of 100 μm or more and drying it.

4. The paper product according to claim 1, characterized in that: The coating is obtained by applying the mannan sol to a thickness of 200 μm or more and drying it.

5. The paper product according to claim 1, characterized in that: The invention includes any one or more of a spoon, a fork, chopsticks, a straw, a stirring stick, a bag, a beverage package, and a food packaging paper.

6. A food container, characterized in that: The invention is a paper product comprising base paper and a coating formed on the base paper. The coating is obtained by applying a neutral or acidic mannan sol obtained by neutralizing a modified mannan in which acetyl groups are released and swelling is suppressed by mixing water, konjac mannan and an alkali and stirring the mixture to release the swelling suppression of the modified mannan, and drying the mixture.

7. The food container according to claim 6, characterized in that It is a paper product used for food.

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