A method for manufacturing a gel-like material, a gel-like material obtained by the said manufacturing method, and a method for using the gel-like material as a hoof protection device for animals.

Abstract

This invention provides a method for manufacturing a gel-like material for hoof protection devices that can be used in the treatment of hoof diseases, etc., which is naturally biodegradable, adhesive, and causes minimal burden on animals even if accidentally ingested. [Solution] The present invention provides a method for producing a gel-like material, comprising: preparing a chitosan solution by dissolving chitin or chitosan in an acid solution; adding gallic acid or plant-derived polyphenols as a crosslinking agent to the chitosan solution to prepare a chitosan pregel solution; and leaving the chitosan pregel solution at a temperature of 0 to 40°C until the water absorption amount, measured in accordance with JIS K 7223-1996, reaches 20 g / g or more, thereby crosslinking the chitosan pregel solution to obtain a gel-like material.

Description

Technical Field

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[0001] The present invention relates to a method for producing a gel-like material, and more particularly to a method for producing a gel-like material that can be suitably used as a hoof protection tool for animals.

Background Art

[0002] Hoof diseases, which are diseases of the hooves of ungulates, have various causes such as bacterial infection, weight load, and nutritional deficiency. As preventive measures, hoof trimming (cutting the hooves), foot bathing, or local spraying with a disinfectant solution to disinfect the hooves are generally performed (for example, Patent Documents 1 and 2). However, inappropriate hoof trimming can cause hoof diseases. In addition, when the organic substances in the foot bath solution are exposed to air, the disinfection effect is lost, and it is important to manage and replace the disinfectant solution to sufficiently disinfect the hooves of animals. However, considering efficiency and economy, it is difficult to prevent and treat hoof diseases by foot bathing.

[0003] As a treatment method for hoof diseases, a method of removing corroded and deteriorated keratin, administering an ointment or an antibiotic to the affected area, protecting the affected area with a gauze, and wrapping the affected area with an eight-shaped bandage or a method of attaching a hoof stand made of a hard wooden board to a healthy hoof with an adhesive, so-called geta method, has been performed. However, the bandage may be contaminated, have poor air permeability, or impair the treatment effect. In addition, in the geta method, a wooden hoof stand made of a hard wooden board has a drawback that it cannot be treated when there is decay on both side hooves. To solve this problem, for example, Patent Document 3 discloses an auxiliary hoof stand for treating hoof diseases made of a water-repellent semi-rigid synthetic resin plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0005] However, these hoof support plates for treating hoof diseases, made of water-repellent, semi-rigid synthetic resin, are not adhesive themselves, and may detach from the hoof during treatment. In such cases, the hoof support does not decompose easily, increasing the burden on the environment, and there is also a risk that the animal may accidentally ingest the detached hoof support, potentially affecting its health.

[0006] In view of the above problems, the object of the present invention is to provide a method for producing a gel-like material for hoof protection devices that can be used in the treatment of hoof diseases, etc., which is naturally biodegradable, adhesive, and places minimal burden on animals even if accidentally ingested. [Means for solving the problem]

[0007] As a result of diligent research, the inventors focused on chitosan gel and found that by using gallic acid or plant-derived polyphenols as crosslinking agents that place less burden on animals even if accidentally ingested, the gelation rate can be adjusted, and as a result, a gel-like material with appropriate adhesiveness and hardness for use as a hoof protection device in the treatment of hoof diseases can be manufactured. The present invention is based on this finding. In other words, the gist of the present invention is as follows.

[0008] [1] A method for producing a gel-like material, Prepare a chitosan solution by dissolving chitin or chitosan in an acid solution. To the chitosan solution, gallic acid or plant-derived polyphenols are added as a crosslinking agent to prepare a chitosan pregel solution. The chitosan pregel solution is left at a temperature of 0 to 40°C until the water absorption, measured in accordance with JIS K 7223-1996, reaches 20 g / g or more, thereby crosslinking the chitosan pregel solution and obtaining a gel-like material. A method for manufacturing a gel-like material, including the following. [2] The method according to [1], wherein the acid solution is acetic acid. [3] The method according to [1], wherein the concentration of chitin or chitosan in the solution is 1 to 20% by mass. [4] The method according to [3], wherein the crosslinking agent is added to the chitin or chitosan in a proportion of 0.01 to 10% by mass. [5] The method according to [1], wherein the plant-derived polyphenols are tea-derived polyphenols. [6] A gel-like material obtained by crosslinking chitin or chitosan with gallic acid or plant-derived polyphenols, A gel-like material whose water absorption capacity, measured according to JIS K 7223-1996, is in the range of 20 to 70 g / g. A method for using the gel-like material described in [7] [6] as a hoof protection device for animals, A method for protecting animal hooves, in which a gel-like material having a water absorption capacity in the range of 20 to 70 g / g, as measured in accordance with JIS K 7223-1996, is used as a hoof protection device, and the hoof protection device naturally falls off the hooves when the water absorption capacity of the gel-like material falls below 20 g / g over time. [8] The method according to [7], wherein the hoof protection device is in the form of a sheet. [Effects of the Invention]

[0009] According to the present invention, by using gallic acid or plant-derived polyphenols as a crosslinking agent and allowing the gelation (crosslinking reaction) of a gel made of chitin or chitosan to proceed until the water absorption capacity reaches 20 g / g or more, a gel-like material suitable as a hoof protection device used in the treatment of hoof diseases can be produced. This material is naturally biodegradable, has adhesive properties, and places minimal burden on animals even if accidentally ingested. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a graph showing the change in water absorption amount of the chitosan gel samples from Examples 1 to 5 over time. [Figure 2] Figure 2 is a graph showing the change in water absorption amount of the chitosan gel samples from Examples 6 to 11 over time. [Modes for carrying out the invention]

[0011] [Method for manufacturing gel-like materials] The method for producing a gel-like material according to the present invention basically includes the steps of preparing a solution in which chitin or chitosan is dissolved (hereinafter also referred to as the "solution preparation step"), preparing a pregel solution by adding a crosslinking agent to the solution (hereinafter also referred to as the "pregel solution preparation step"), and obtaining a gel-like material by crosslinking the pregel solution (hereinafter also referred to as the "pregel solution crosslinking step"). Each step will be described in detail below.

[0012] [Steps for preparing a chitin or chitosan solution] In the method for producing a gel-like material according to the present invention, chitin or chitosan is used as the raw material for the gel-like material. Chitin is an insoluble polysaccharide (β-poly-N-acetyl-D-glucosamine) to which the monosaccharide N-acetyl-D-glucosamine is bonded, and chitosan is a product or derivative of chitin obtained by deacetylation, and includes not only chitosan (β-poly-D-glucosamine) and its derivatives, but also chitosan salts and those containing unreacted chitin and its derivatives. The chitin or chitosan that can be used in the present invention is not particularly limited, but from the viewpoint of solubility when dissolving in an acid solution as described later, for example, when using an acid solution such as acetic acid, chitosan with a degree of deacetylation of 50% or more can be preferably used, more preferably 70% or more, and particularly preferably 90% or more. The degree of deacetylation indicates the proportion of chitosan in the chitin derivative.

[0013] These chitins and chitosans are contained in the exoskeletons of insects and crustaceans, the cell walls of fungi, etc. in the biological world and have biocompatibility. The "biocompatibility" mentioned here means that the substance shows no significant harmful or unwanted effects on the living body. In addition, since chitosan and chitin contain nitrogen, they show various physiological activities such as hemostatic effects and antibacterial properties, and are also used as raw materials for wound dressing materials, which can improve the erosion state of the affected area, have excellent absorbency of exudate, suppress the growth of bacteria, and prevent the deterioration of hoof diseases. Therefore, even if animals accidentally ingest the gelling material made from chitosan, the burden on the animals is small.

[0014] The main components of chitosans are not particularly limited. For example, chitosan, N-allyl chitosan, N-alkyl chitosan, O-allyl chitosan, O-alkyl chitosan, sulfated chitosan, nitrated chitosan, carboxymethylated chitosan, etc. can be mentioned, but chitosan and carboxymethylated chitosan are preferred.

[0015] Since many of the above-mentioned chitins or chitosans are insoluble in water as they are, they are dissolved in an acid solution to prepare a solution. The acid solution capable of dissolving chitin or chitosans is not particularly limited, and an acidic aqueous solution obtained by dissolving organic acids such as acetic acid, lactic acid, gluconic acid, malic acid, citric acid, or inorganic acids such as hydrochloric acid can be used. However, from the perspective of the burden on animals and environmental burden even in case of accidental ingestion, organic acids such as acetic acid, glacial acetic acid, and lactic acid can be preferably used.

[0016] The concentration of chitin or chitosans in the solution obtained as described above is preferably in the range of 1 to 20% by mass, more preferably 5 to 15% by mass, and particularly preferably 8 to 10% by mass. If the concentration of chitin or chitosans in the solution is too low, it becomes difficult for chitin or chitosan to gel in the pregel solution crosslinking step described later. Also, if the concentration of chitin or chitosans in the solution is too high, the solution viscosity becomes high and it becomes difficult to mold when gelled. Water may be added as appropriate to adjust the viscosity of the chitosan solution.

[0017] Although it depends on the acid solution used, when acetic acid is used as the acid solution, chitosans are added up to a ratio of 25 parts by mass to 100 parts by mass of an aqueous acetic acid solution (3% acetic acid), and by mixing the two, chitosans can be dissolved well, and a chitosan solution can be prepared. The temperature at which chitosans are dissolved in the acid solution is not particularly limited, and for example, it can be carried out at room temperature.

[0018] [Chitosan pre-gel solution preparation step] In the method for producing the gel-like material of the present invention, next, gallic acid or plant-extracted polyphenols are added as a cross-linking agent to the solution obtained as described above to prepare a pre-gel solution. A solution in which chitin or chitosan is dissolved gels by performing a neutralization treatment even without adding a cross-linking agent, but in the present invention, gallic acid or plant-extracted polyphenols are used as the cross-linking agent. By adding a cross-linking agent, the gelation rate (degree of cross-linking) at the time of gelation can be easily adjusted, and as a result, the time to reach a predetermined water absorption amount can be appropriately adjusted.

[0019] Gallic acid and plant-extracted polyphenols impose little burden on animals even if ingested, and can reduce the environmental burden when the gel-like material falls off or is discarded in the soil. Gallic acid is a compound represented by the following formula, and is a kind of polyphenol having a basic skeleton of hydrolyzable tannin contained in gallnuts, Chinese gallnuts, tea leaves, brewed wine, etc. Gallic acid may be an anhydride or a hydrate (for example, gallic acid monohydrate). [Chemical formula]

[0020] Examples of plant-derived polyphenols include isoflavones found in soybeans and kinako (roasted soybean flour), quercetin found in onions, apples, and shallots, anthocyanins (e.g., anthocyanins) found in red wine, blueberries, and black beans, sesamin found in sesame seeds, theaflavins found in black tea, hesperidin found in yuzu, Satsuma oranges, and lemons, luteolin found in bell peppers, garland chrysanthemum, and celery, naringin found in grapefruit and hassaku oranges, tannins found in lotus root, chlorogenic acid found in prunes, plums, burdock, and coffee, mumefural found in plums, and tea-derived polyphenols (also called polymerized tea catechins) which are polymers of catechins. Furthermore, tea-extracted polyphenols refer to structures in which multiple unpolymerized monomeric catechins ((+)-catechin, (-)-epicatechin, (+)-gallocatechin, (-)-epigallocatechin, (-)-catechin gallate, (-)-epicatechin gallate, (-)-gallocatechin gallate, (-)-epigallocatechin gallate) are linked together by tea-derived enzymes, light, pH changes, etc. Among the plant-extracted polyphenols described above, tea-extracted polyphenols can be preferably used.

[0021] The amount of crosslinking agent added to a solution of chitin or chitosan is preferably 0.01 to 10% by mass, more preferably 0.03 to 5% by mass, and particularly preferably 0.05 to 3% by mass, relative to the mass of chitin or chitosan in the solution. If the amount of crosslinking agent added is less than the above range, gelation will not proceed, making it difficult to obtain a gelling material with the desired water absorption capacity. Conversely, if the amount of crosslinking agent is more than the above range, gelation will proceed too much, and the period (time) during which the gelling material with the desired water absorption capacity is obtained tends to be shortened.

[0022] [Chitosan Pregel Solution Crosslinking Process] The chitosan pregel solution obtained as described above undergoes a gelation reaction over time, increasing its degree of crosslinking. As a result, the water absorption capacity of the chitosan gel changes over time. Specifically, after a few days to two weeks, the gel becomes hard enough to maintain its shape (e.g., sheet-like), and thereafter, the water absorption capacity increases over time. After reaching its maximum value, the water absorption capacity gradually decreases as gelation progresses. In this invention, the chitosan pregel solution is left to gel, and the resulting gel with a water absorption capacity of 20 g / g or more is used as the gel material. In this invention, water absorption capacity refers to the water absorption capacity measured in accordance with JIS K 7223-1996 (Test method for water absorption capacity of superabsorbent polymers). Specifically, it can be measured as follows.

[0023] First, prepare a nylon mesh bag with a mesh opening of 57 μm and 255 mesh (for example, a nylon mesh bag that is 10 cm wide and 20 cm deep). From the resulting gel-like substance, cut out several samples of approximately 1 g each and place them in a nylon mesh bag (let's call the mass of the sample placed in the bag a (g)). Fill a 1L beaker with water and immerse the nylon mesh bag containing the sample in it up to 150mm from the bottom of the bag. After 24 hours of soaking, remove the nylon mesh bag from the water and hang it up for 10 minutes to drain the water. Measure the mass of the drained nylon mesh bag (let's call this mass b(g)). The same test is performed on nylon mesh bags that do not contain a sample, and the mass of the drained nylon mesh bags is measured (let's call the measured mass c(g)). The water absorption rate W (g / g) is defined as the value calculated by the following formula. W=(bca) / a

[0024] The time it takes for the water absorption to reach 20 g / g or more varies depending on the properties of the chitosan pregel solution used (for example, the amount of crosslinking agent added and the type of crosslinking agent used).

[0025] [Applications of gelling materials] The gelled material obtained as described above can be suitably used as a hoof protection device for animals. A gelled material having a predetermined water absorption capacity is adhesive and can be attached to the sole of an animal's hoof. In one embodiment of the present invention, a gel-like material having a water absorption capacity in the range of 20 to 70 g / g, as measured in accordance with JIS K 7223-1996, is used as a hoof protection device for animals. As the water absorption capacity of the gel-like material falls below 20 g / g over time, the hoof protection device will naturally detach from the hoof. That is, as gelation progresses and the water absorption capacity falls below 20 g / g, the adhesiveness decreases and the hoof protection device made of the gel-like material naturally detaches. In the present invention, the period during which the water absorption capacity of the gel-like material is in the range of 20 to 70 g / g (i.e., the period during which the gel-like material has suitable adhesiveness) is preferably 10 hours to 2 months, and more preferably half a day to 2 weeks, under the usage environment. Furthermore, the above period can be extended by storing the gel-like material with a water absorption capacity of 20 g / g or more in a cool place (for example, in a refrigerator). Therefore, by storing the obtained gelling material in a cool place and removing it from the cool place when needed, it is possible to maintain a period in which the water absorption capacity is in the range of 20 to 70 g / g.

[0026] As described above, the gel-like material of the present invention is composed solely of biocompatible materials. Therefore, even if an animal were to accidentally ingest the gel-like material after it has naturally detached, it is considered that the impact on the animal's body would be minimal. Furthermore, the gel-like material composed of the above-mentioned materials is considered to have minimal environmental impact even if it is discarded into the environment due to natural detachment. [Examples]

[0027] The present invention will be described in detail below with reference to examples, but the technical scope of the present invention is not limited to the examples. Unless otherwise specified, "%" means mass%.

[0028] [Preparation of Pregel solution] Chitosan (viscosity 19 mPa·s, degree of deacetylation 84%) was dissolved in a 3% aqueous acetic acid solution to prepare a chitosan solution. Three different chitosan solutions with chitosan concentrations of 8% by mass, 9% by mass, and 10% by mass were prepared by varying the amount of chitosan added. Next, gallic acid monohydrate was added as a crosslinking agent to the obtained chitosan solution to prepare a chitosan pregel solution. At this time, four types of chitosan pregel solutions were prepared by varying the amount of gallic acid monohydrate added.

[0029] [Gel preparation] The obtained Pregel solution was filled into containers of a predetermined size and left to stand at room temperature. Gel sheets of different thicknesses were prepared by varying the amount of Pregel solution used. Details of the sheet-like chitosan gel samples used in the experiment are shown in Table 1 below.

[0030] [Table 1]

[0031] The amount of water absorbed by each chitosan gel sample was measured after leaving it at room temperature for several days to approximately 120 days. The amount of water absorbed was calculated by measuring the masses of a, b, and c according to the test method described above in accordance with JIS K 7223-1996, and using the following formula: W=(bca) / a It was calculated using the method described below.

[0032] The time-dependent changes in water absorption of the chitosan gel samples from Examples 1 to 5 are shown in Figure 1. As is clear from Figure 1, the chitosan gel of Example 1 dissolved when immersed in water until 13 days after the preparation of the pregel solution, and swelled after 23 days. Similarly, the chitosan gel of Example 2 dissolved when immersed in water until 6 days after the preparation of the pregel solution, and swelled after 20 days. Furthermore, the chitosan gels of Examples 3 to 5 dissolved when immersed in water until 7 days after the preparation of the pregel solution, and swelled after 11 days. Thus, it can be seen that the water absorption of the chitosan gel (water absorption of 20 g / g or more) can be adjusted by the chitosan concentration and the crosslinking agent concentration. It can also be seen that the water absorption reaches its maximum after a predetermined time has elapsed, and then gradually decreases over time. Note that the "×" marks in the graph of Figure 1 indicate that the gel has hardened at that point and is no longer suitable as a gel material.

[0033] As described above, the chitosan gel sample from Example 1 dissolved when immersed in water 13 days after the preparation of the pregel solution, but it swelled after 23 days and maintained a water absorption capacity of 20 g / g or more until 28 days later. On the other hand, the chitosan gel sample after 34 days had a water absorption capacity of less than 20 g / g and the gel had hardened, making it unsuitable as a gel material. Furthermore, as described above, the chitosan gel sample from Example 2 eluted when immersed in water 6 days after the preparation of the pregel solution, but it swelled after 20 days and was able to maintain a water absorption capacity of 20 g / g or more until at least 70 days later. Furthermore, as described above, the chitosan gel sample from Example 3 dissolved when immersed in water 7 days after the preparation of the pregel solution, but it swelled after 11 days and was able to maintain a water absorption capacity of 20 g / g or more until 21 days later. On the other hand, the chitosan gel sample after 26 days had a water absorption capacity of less than 20 g / g, and the gel had hardened, making it unsuitable as a gel material. Furthermore, as described above, the chitosan gel sample of Example 4 eluted when immersed in water 7 days after the preparation of the pregel solution, but it swelled after 11 days and was able to maintain a water absorption capacity of 20 g / g or more until at least 74 days later. Furthermore, as described above, the chitosan gel sample of Example 5 eluted when immersed in water 7 days after the preparation of the pregel solution, but it swelled after 11 days and was able to maintain a water absorption capacity of 20 g / g or more until at least 40 days later.

[0034] Next, for each chitosan gel sample from Examples 1 to 5, the adhesiveness of the gelling material was evaluated by attaching the chitosan gel sample to a cow's horn (similar to the adhesiveness to animal hooves) and assessing the degree of peeling. The evaluation criteria were as follows. ○: The sheet adheres firmly to the surface of the beef horn, making it difficult to peel off by hand. △: The sheet is attached to the surface of the beef horn, but it can be easily peeled off by hand. ×: Part of the sheet is peeling off from the cow horn surface. The evaluation results are shown in Table 2 below. Note that "-" in Table 2 indicates the state before gelation.

[0035] [Table 2]

[0036] Considering the adhesiveness evaluation results shown in Table 2 together with the change in water absorption over time shown in Figure 1, it can be seen that the gel-like material exhibits adhesiveness in the range of water absorption from 20 to 70 g / g, and that the adhesiveness decreases when the water absorption drops below 20 g / g.

[0037] Four types of sheet-like chitosan gel samples, Examples 6-9, were prepared in the same manner as described above, except that tea-extracted polyphenols (Sunphenon 90S-OP, manufactured by Taiyo Kagaku Co., Ltd.) were used as the crosslinking agent instead of gallic acid monohydrate. Additionally, two types of sheet-like chitosan gel samples, Examples 10 and 11, were prepared in the same manner as described above, except that tea-extracted polyphenols (GREEN TEA PE, manufactured by BHN Co., Ltd.) were used as the crosslinking agent instead of gallic acid monohydrate. Details of the sheet-like chitosan gel samples used in the experiments are shown in Table 3 below.

[0038] [Table 3]

[0039] The time-dependent changes in water absorption of the chitosan gel samples from Examples 6-11 are shown in Figure 2. As is clear from Figure 2, it can be seen that the water absorption reaches 20 g / g or more approximately 7 days after the preparation of the chitosan gel. Furthermore, it can be seen that the water absorption reaches its maximum after a predetermined time has elapsed, and then gradually decreases over time. Note that the "×" marks in the graph of Figure 2 indicate that the gel has hardened at that point and is no longer suitable as a gel material.

[0040] The chitosan gel sample from Example 6 swells 11 days after the preparation of the pregel solution and maintains a water absorption capacity of 20 g / g or more until 18 days later. On the other hand, the chitosan gel sample after 21 days has a water absorption capacity of less than 20 g / g, indicating that the gel has hardened and is unsuitable as a gel-like material. Furthermore, the chitosan gel sample from Example 7 eluted when immersed in water 6 days after the preparation of the pregel solution, but it swelled after 20 days and was found to be able to maintain a water absorption capacity of 20 g / g or more for at least 42 days. The chitosan gel sample from Example 8 swells 7 days after the preparation of the pregel solution and can maintain a water absorption capacity of 20 g / g or more until at least 74 days have passed. The chitosan gel samples from Examples 9-11 swelled starting 7 days after the preparation of the pregel solution, and were found to maintain a water absorption capacity of 20 g / g or more until at least 40 days later.

[0041] Furthermore, the tackiness of the gelling material was evaluated for each chitosan gel sample from Examples 6 to 11 in the same manner as described above. The evaluation results are shown in Table 4 below. In Table 4, "-" indicates the state before gelation.

[0042] [Table 4]

[0043] Considering the adhesiveness evaluation results shown in Table 4 together with the change in water absorption over time shown in Figure 2, it can be seen that the gel-like material exhibits adhesiveness in the range of water absorption from 20 to 70 g / g, and that the adhesiveness decreases when the water absorption drops below 20 g / g.

Claims

1. A method for producing a gel-like material, Prepare a solution by dissolving chitin or chitosan in an acid solution, To the aforementioned solution, gallic acid or plant-derived polyphenols are added as a crosslinking agent to prepare a pregel solution. The aforementioned Pregel solution is left at a temperature of 0 to 40°C until the water absorption, measured in accordance with JIS K 7223-1996, reaches 20 g / g or more, thereby crosslinking the Pregel solution and obtaining a gel-like material. A method for manufacturing a gel-like material, including the following.

2. The method according to claim 1, wherein the acid solution is acetic acid.

3. The method according to claim 1, wherein the concentration of chitin or chitosan in the solution is 1 to 20% by mass.

4. The method according to claim 3, wherein the crosslinking agent is added to the chitin or chitosan in a proportion of 0.01 to 10% by mass.

5. The method according to claim 1, wherein the plant-derived polyphenols are tea-derived polyphenols.

6. A gel-like material obtained by crosslinking chitin or chitosan with gallic acid or plant-derived polyphenols, A gel-like material whose water absorption capacity, measured according to JIS K 7223-1996, is in the range of 20 to 70 g / g.

7. A method for using the gel-like material described in claim 6 as a hoof protection device for animals, A method for protecting an animal's hoof, in which a gel-like material having a water absorption capacity in the range of 20 to 70 g / g, as measured in accordance with JIS K 7223-1996, is used as a hoof protection device, and the hoof protection device naturally detaches from the hoof when the water absorption capacity of the gel-like material falls below 20 g / g over time.

8. The method according to claim 7, wherein the hoof protection device is in the form of a sheet.

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