Mastitis prevention sheet and method for producing mastitis prevention sheet

Abstract

A mastitis prevention sheet includes a base material layer, and an adhesive layer supported by the base material layer. The adhesive layer contains chitosan, a saturated carboxylic acid, and a cured product of an adhesive for forming the adhesive layer. The percentage of the mass of the chitosan with respect to the mass of a main agent of the adhesive in the cured product of the adhesive is 6% by mass or more. The percentage of the mass of the saturated carboxylic acid with respect to the mass of the main agent is 3% by mass or more.

Description

Mastitis prevention sheet, and method for manufacturing a mastitis prevention sheet.

[0001] This disclosure relates to a mastitis prevention sheet and a method for manufacturing a mastitis prevention sheet.

[0002] One example of a teat opening protection patch for livestock comprises a laminate consisting of an elastic sheet and an adhesive layer. The adhesive layer is laminated over the entire surface of one side of the elastic sheet. The teat opening protection patch may be contaminated with chitosan, which has antibacterial activity, to enhance its function of protecting the teat opening. When the teat opening protection patch is used, the adhesive layer of the laminate is applied to the teat of the livestock so as to cover the teat opening. This protects the teat opening with the laminate, thereby preventing the livestock from becoming infected with bacteria or other pathogens through the teat opening, and consequently reducing the risk of mastitis in the livestock. The duration for which the teat opening protection patch is applied is set to about 10 days to 2 weeks for livestock in the dry period, which are susceptible to bacterial infections (see, for example, Patent Document 1).

[0003] International Publication No. 2017 / 150203

[0004] Incidentally, if the surrounding environment for livestock is hot and humid, the teat opening protection patches attached to the teat openings of the livestock will also be exposed to high temperatures and humidity for extended periods. As a result, the antibacterial activity of chitosan may be deactivated during the period in which the teat opening protection patches are used.

[0005] One embodiment of a mastitis prevention sheet comprises a base layer and an adhesive layer supported by the base layer. The adhesive layer contains chitosan, a saturated carboxylic acid, and a cured product of an adhesive for forming the adhesive layer. In the cured product of the adhesive, the percentage of the mass of the chitosan relative to the mass of the main component of the adhesive is 6% by mass or more, and the percentage of the mass of the saturated carboxylic acid relative to the mass of the main component is 3% by mass or more.

[0006] One embodiment of a mastitis prevention sheet comprises a base layer and an adhesive layer supported by the base layer. The adhesive layer contains chitosan, a hydroxycarboxylic acid, and a cured product of an adhesive for forming the adhesive layer. In the cured product of the adhesive, the percentage of the mass of the chitosan relative to the mass of the main component of the adhesive is 3% by mass or more, and the percentage of the mass of the hydroxycarboxylic acid relative to the mass of the main component is 3% by mass or more.

[0007] One embodiment of a mastitis prevention sheet comprises a base layer and an adhesive layer supported by the base layer. The adhesive layer contains chitosan, a saturated carboxylic acid, a cured product of an adhesive for forming the adhesive layer, and an alcohol. The percentage of the mass of the chitosan in the cured product of the main component of the adhesive is 3% by mass or more, the percentage of the mass of the saturated carboxylic acid in relation to the mass of the main component is 1.5% by mass or more, and the percentage of the mass of the alcohol in relation to the mass of the main component is 40% by mass or more.

[0008] One embodiment of a method for manufacturing a mastitis prevention sheet is a method for manufacturing a mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer. The manufacturing method includes forming the base layer, forming the adhesive layer, and laminating the adhesive layer to the base layer. Forming the adhesive layer includes preparing a coating solution containing the main component, the chitosan, and the saturated carboxylic acid such that the percentage of chitosan by mass relative to the solid content of the main component of the adhesive for forming the adhesive layer is 6% by mass or more, and the percentage of saturated carboxylic acid by mass relative to the solid content of the main component is 3% by mass or more.

[0009] One embodiment of a method for manufacturing a mastitis prevention sheet is a method for manufacturing a mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer. The manufacturing method includes forming the base layer, forming the adhesive layer, and laminating the adhesive layer to the base layer. Forming the adhesive layer includes preparing a coating solution containing the main component, the chitosan, and the hydroxycarboxylic acid such that the percentage of chitosan by mass relative to the solid content of the main component of the adhesive for forming the adhesive layer is 3% by mass or more, and the percentage of hydroxycarboxylic acid by mass relative to the solid content of the main component is 3% by mass or more.

[0010] One embodiment of a method for manufacturing a mastitis prevention sheet is a method for manufacturing a mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer. The manufacturing method includes forming the base layer, forming the adhesive layer, and laminating the adhesive layer to the base layer. Forming the adhesive layer includes preparing a coating solution containing the main component, the chitosan, the saturated carboxylic acid, and the alcohol such that the percentage of chitosan by mass relative to the solid content of the main component of the adhesive for forming the adhesive layer is 3% by mass or more, the percentage of saturated carboxylic acid by mass relative to the solid content of the main component is 1.5% by mass or more relative to the percentage of chitosan by mass, and the percentage of alcohol by mass relative to the solid content of the main component is 40% by mass or more.

[0011] Figure 1 is a cross-sectional view showing the structure of the mastitis prevention sheet in the first embodiment. Figure 2 is a plan view showing the structure of the first example of the mastitis prevention sheet. Figure 3 is a plan view showing the structure of the second example of the mastitis prevention sheet. Figure 4 is a plan view showing the structure of the third example of the mastitis prevention sheet. Figure 5 is a flowchart for explaining the process of forming the base layer included in the manufacturing method of the mastitis prevention sheet. Figure 6 is a flowchart for explaining the process of forming the adhesive layer included in the manufacturing method of the mastitis prevention sheet. Figure 7 is a flowchart showing the process of forming the mastitis prevention sheet included in the manufacturing method of the mastitis prevention sheet. Figure 8 is a process diagram showing one step included in the method of using the mastitis prevention sheet. Figure 9 is a process diagram showing one step included in the method of using the mastitis prevention sheet. Figure 10 is a process diagram showing one step included in the method of using the mastitis prevention sheet. Figure 11 is a process diagram showing one step included in the method of using the mastitis prevention sheet. Figure 12 is a table showing the evaluation results of the mastitis prevention sheets of the examples and comparative examples. Figure 13 is a cross-sectional view showing the structure of a modified example of the mastitis prevention sheet. Figure 14 is a process diagram showing one step included in the manufacturing method of the modified mastitis prevention sheet. Figure 15 is a process diagram showing one step included in the manufacturing method of the modified mastitis prevention sheet. Figure 16 is a process diagram showing one step included in the manufacturing method of the modified mastitis prevention sheet. Figure 17 is a process diagram showing one step included in the manufacturing method of the modified mastitis prevention sheet. Figure 18 is a process diagram showing one step included in the manufacturing method of the modified mastitis prevention sheet.

[0012] [First Embodiment] A first embodiment of a mastitis prevention sheet and a method for manufacturing a mastitis prevention sheet will be described with reference to Figures 1 to 11.

[0013] [Mastitis Prevention Sheet] As shown in Figure 1, the mastitis prevention sheet 10 comprises a base layer 11 and an adhesive layer 12 supported by the base layer 11. The mastitis prevention sheet 10 comprises a sheet body 10B including the base layer 11 and the adhesive layer 12. In the example shown in Figure 1, the adhesive layer 12 is in contact with the base layer 11. A printing layer, for example, may be located between the adhesive layer 12 and the base layer 11.

[0014] In the adhesive layer 12, the side opposite to the side facing the base layer 11 is the adhesive surface 12S. In the example shown in Figure 1, since the adhesive layer 12 is in contact with the base layer 11, the side of the adhesive layer 12 opposite to the side in contact with the base layer 11 is the adhesive surface 12S. The mastitis prevention sheet 10 is attached to the teats of livestock so that the adhesive surface 12S included in the sheet body 10B does not come into contact with the teat openings of the livestock. The livestock may be, for example, dairy cows.

[0015] The adhesive layer 12 contains chitosan, a saturated carboxylic acid, and a cured product of the adhesive for forming the adhesive layer 12. The mastitis prevention sheet 10 of this embodiment satisfies the following conditions: (Condition 1) The percentage of the mass of chitosan relative to the mass of the main component of the adhesive in the cured product of the adhesive is 6% by mass or more. (Condition 2) The percentage of the mass of saturated carboxylic acid relative to the mass of the main component of the adhesive in the cured product of the adhesive is 3% by mass or more.

[0016] According to the mastitis prevention sheet 10, even when the mastitis prevention sheet 10 is used under high temperature and high humidity conditions, it is possible to suppress the deactivation of the antibacterial effect of the mastitis prevention sheet 10. For example, the mastitis prevention sheet 10 does not lose its antibacterial effect even when left undisturbed for two weeks in a high temperature and high humidity environment where the temperature is 40°C and the relative humidity is 90%. The antibacterial effect of chitosan is confirmed by a method in accordance with JIS Z 2801:2010 "Antibacterial processed products - Antibacterial test methods and antibacterial effect". Since the cured product of the adhesive is composed of the solid content of the main component and the solid content of the curing agent, the mass of the main component of the adhesive in the cured product is equal to the amount of solid content of the main component in the adhesive.

[0017] The number of carbon atoms in the hydrocarbon chain of a saturated carboxylic acid, that is, the number of carbon atoms other than those in the carboxyl group (COOH) of a saturated carboxylic acid, may be between 1 and 3. A carboxylic acid having 1 to 3 carbon atoms in its hydrocarbon chain is acetic acid (CH₃). ３ -COOH), propionic acid (CH ３ CH ２ -COOH), butyric acid (CH ３ (CH ２ ) ２It is a -COOH compound. An acidic compound, preferably acetic acid.

[0018] The adhesive is a two-component adhesive, consisting of a main component and a curing agent. The adhesive may be, for example, an acrylic adhesive or a urethane adhesive. A urethane adhesive is preferred.

[0019] In the example shown in Figure 1, the mastitis prevention sheet 10 further comprises a protective layer 13 and a release layer 14. The surface 11S of the base layer 11 is the surface opposite to the surface in contact with the adhesive layer 12. The protective layer 13 is in contact with the surface 11S of the base layer 11. The protective layer 13 covers the entire surface 11S of the base layer 11. The release layer 14 is in contact with the adhesive surface 12S of the adhesive layer 12. The release layer 14 covers the entire adhesive surface 12S of the adhesive layer 12.

[0020] Figure 2 shows a first example of the planar structure of the mastitis prevention sheet 10 as viewed from a viewpoint opposite to the plane on which the mastitis prevention sheet 10 is spread. As shown in Figure 2, the mastitis prevention sheet 10 has a flat shape before use. Viewed from a viewpoint opposite to the plane on which the mastitis prevention sheet 10 is spread, the outer edge 10E of the mastitis prevention sheet 10 has a rectangular shape extending along the first direction D1. The outer edge 10E of the mastitis prevention sheet 10 coincides with the outer edge of the protective layer 13.

[0021] The protective layer 13 comprises a first region 13R1 and a second region 13R2. Each region 13R1 and 13R2 extends along a first direction D1, and the first region 13R1 and the second region 13R2 are aligned along a second direction D2 that is perpendicular to the first direction D1. The second region 13R2 is the region within the protective layer 13 that is in contact with the base layer 11. In contrast, the first region 13R1 is the region within the protective layer 13 that is not in contact with the base layer 11.

[0022] The length of the protective layer 13 along the first direction D1 may be, for example, 100 mm or more and 150 mm or less. The length of the first region 13R1 along the second direction D2 may be, for example, 5 mm or more and 20 mm or less. The length of the second region 13R2 along the second direction D2 may be, for example, 50 mm or more and 100 mm or less.

[0023] When viewed from a viewpoint opposite to the plane on which the mastitis prevention sheet 10 is spread, the base layer 11 has the same shape and size as the second region 13R2 of the protective layer 13 and overlaps the entire second region 13R2. When viewed from a viewpoint corresponding to the plane on which the mastitis prevention sheet 10 is spread, the adhesive layer 12 and the release layer 14 have the same shape and size as the base layer 11 and overlap the entire base layer 11.

[0024] The protective layer 13 has two cuts 13B in the first region 13R1. Each cut 13B extends from the outer edge of the protective layer 13 toward the base layer 11. The cuts 13B have a length that does not reach the base layer 11. In the example shown in Figure 2, each cut 13B extends along the second direction D2. Each cut 13B extends from the portion of the outer edge of the protective layer 13 that extends along the first direction D1 and is included in the first region 13R1 toward the base layer 11. Each cut 13B may also extend along a direction intersecting the second direction D2. Because the protective layer 13 has cuts 13B, when peeling the protective layer 13 from the base layer 11, it is possible to tear the protective layer 13 along the cuts 13B, thereby peeling the protective layer 13 from the base layer 11. Therefore, it is easy to peel the protective layer 13 from the base layer 11.

[0025] The distance D13B between the cuts 13B in the first direction D1 may be, for example, 3 mm or more and 40 mm or less. This makes it easier to grasp the portion of the protective layer 13 located between the cuts 13B. The center of the mastitis prevention sheet 10 in the first direction D1 may be located between the cuts 13B. This makes it possible to tear the protective layer 13 at approximately the center of the first direction D1 by tearing the protective layer 13 along the cuts 13B. The mastitis prevention sheet 10 may have only one cut 13B or it may have three or more cuts 13B.

[0026] Figure 3 shows a second example of the planar structure of the mastitis prevention sheet 10 as viewed from a viewpoint opposite to the plane on which the mastitis prevention sheet 10 extends. As shown in Figure 3, the mastitis prevention sheet 10 may have a substantially trapezoidal shape. However, each side of the outer edge 10E of the mastitis prevention sheet 10 that extends along the first direction D1 has a bending point at the boundary between the first region 13R1 and the second region 13R2 of the protective layer 13.

[0027] In the protective layer 13, a first region 13R1 and a second region 13R2 are aligned along a first direction D1. The first region 13R1 and the second region 13R2 each have a trapezoidal shape. The second region 13R2 has a trapezoidal shape that tapers in the direction from the second region 13R2 toward the first region 13R1 in the first direction D1. The first region 13R1 has a trapezoidal shape that tapers more steeply than the second region 13R2 in the direction from the second region 13R2 toward the first region 13R1 in the first direction D1.

[0028] The base layer 11, adhesive layer 12, and release layer 14 have the same size and shape as the second region 13R2 of the protective layer 13 when viewed from a viewpoint opposite to the plane on which the mastitis prevention sheet 10 is spread. The base layer 11, adhesive layer 12, and release layer 14 overlap the entire second region 13R2.

[0029] The second example of the mastitis prevention sheet 10 shown in Figure 3 may also have a slit 13B. In this case, the mastitis prevention sheet 10 may have a slit 13B located in the first region 13R1 of the protective layer 13 and extending, for example, along the second direction D2 from the outer edge 10E of the mastitis prevention sheet 10 toward the second region 13R2. The mastitis prevention sheet 10 may have a slit 13B located in the first region 13R1 of the protective layer 13 and extending, for example, along the first direction D1 from the outer edge 10E of the mastitis prevention heat 10 toward the second region 13R2. The mastitis prevention sheet 10 may have only one slit 13B or two or more.

[0030] Furthermore, the shape of the outer edge 10E and each layer of the mastitis prevention sheet 10 is not limited to the rectangular and trapezoidal shapes described above. For example, the outer edge 10E and each layer may have polygonal shapes other than squares, or they may have circular or elliptical shapes.

[0031] Figure 4 shows a third example of the planar structure of the mastitis prevention sheet 10 as viewed from a viewpoint corresponding to the plane on which the mastitis prevention sheet 10 extends. As shown in Figure 4, the mastitis prevention sheet 10 may have a substantially rectangular shape. The third example of the mastitis prevention sheet 10 comprises one second region 13R2 and two first regions 13R1 that sandwich the second region 13R2 in a first direction D1. The second region 13R2 has a rectangular shape that extends along the first direction D1. Of each first region 13R1, the portion included in the outer edge 10E is composed of two arc-shaped portions that are connected along the second direction D2. Each arc-shaped portion has a curvature such that its center of curvature is located within the first region 13R1.

[0032] The protective layer 13 has a cut 13C that extends along the first direction D1. The cut 13C extends from the boundary between two arc-shaped portions in the first first region 13R1 to the boundary between two arc-shaped portions in the second first region 13R1. Thus, since the protective layer 13 has a cut 13C that extends throughout the entire mastitis prevention sheet 10 in the first direction D1, the protective layer 13 is easily peeled off from the base layer 11 along the cut 13C.

[0033] The mastitis prevention sheet 10 has a region including the center of the second region 13R2 and has a plurality of cuts 10C near the outer edge 10E. Each cut 10C extends along the second direction D2, and the plurality of cuts 10C are arranged at equal intervals along the first direction D1. Each cut 10C has a length of less than half the distance between the outer edge 10E and the cut 13C in the second direction D2. Because the mastitis prevention sheet 10 has cuts 10C, milk leaking from the nipple opening can be discharged through the cuts 10C. Because the cuts 10C extend along the second direction D2, the base layer 11 and the adhesive layer 12 are less likely to tear when the mastitis prevention sheet 10 is attached to the nipple.

[0034] [Method for producing mastitis prevention sheet] Referring to FIGS. 5 to 7, a method for producing mastitis prevention sheet 10 will be described. The method for producing mastitis prevention sheet 10 according to the present embodiment includes forming a base material layer 11, forming an adhesive layer 12, and laminating the adhesive layer 12 onto the base material layer 11.

[0035] Forming the adhesive layer 12 includes preparing a coating liquid so as to satisfy the following conditions. (Condition 3) The percentage by mass of chitosan relative to the solid content in the main agent of the adhesive for forming the adhesive layer 12 is 6% by mass or more. (Condition 4) The percentage by mass of saturated carboxylic acid relative to the solid content of the main agent is 3% by mass or more.

[0036] Hereinafter, with reference to the drawings, the method for producing mastitis prevention sheet 10 will be described in more detail. In the production of the mastitis prevention sheet 10, after the base material layer 11 and the adhesive layer 12 included in the mastitis prevention sheet 10 are individually formed, the adhesive layer 12 is laminated onto the base material layer 11. Hereinafter, the step of producing the base material layer 11 will be described with reference to FIG. 5, the step of producing the adhesive layer 12 will be described with reference to FIG. 6, and the step of producing the mastitis prevention sheet 10 by attaching the adhesive layer 12 to the base material layer 11 will be described with reference to FIG. 7.

[0037] As shown in FIG. 5, the step of producing the base material layer 11 includes a first coating film forming step (step S11), a drying step (step S12), and an aging step (step S13). Specifically, in the first coating film forming step, a first coating film is formed using a first coating liquid for forming the base material layer 11 (step S11). At this time, the first coating film is formed on one surface of the protective layer 13. Next, the first coating film is dried in the drying step (step S12). The thickness of the first coating film after drying may be, for example, 5 µm or more and 30 µm or less. Thereafter, the base material layer 11 can be obtained from the first coating film by aging the dried first coating film in the aging step (step S13). Thereby, a first laminate composed of the base material layer 11 and the protective layer 13 can be obtained. The thickness of the base material layer 11 obtained after aging is equal to the thickness of the first coating film after drying.

[0038] The protective layer 13 is formed from a synthetic resin. The protective layer 13 may be formed of, for example, a base sheet and a release layer. In this case, the release layer is laminated on the base sheet. When the protective layer 13 includes a base sheet and a release layer, the release layer is in contact with the base material layer 11. The base sheet may be formed from, for example, either a polyolefin resin or a polyester resin. The polyester resin may be, for example, a polyethylene terephthalate resin. The polyolefin resin may be, for example, a polypropylene resin. The base sheet is preferably formed from a polyolefin resin. The base sheet may be any one of a uniaxially stretched sheet, a biaxially stretched sheet, and an unstretched sheet. The release layer may be formed from, for example, a silicone resin.

[0039] The protective layer 13 may be composed only of the above-mentioned base sheet. In this case, in the base sheet, the contact surface that comes into contact with the base material layer 11 may be subjected to processing for facilitating peeling of the base material layer 11 from the base sheet. The processing for the contact surface of the base sheet may be, for example, embossing. The thickness of the protective layer 13 may be, for example, 30 µm or more and 400 µm or less.

[0040] The base material layer 11 is formed from a synthetic resin. A first coating liquid for forming the base material layer 11 contains a material capable of forming a synthetic resin layer after the first coating liquid is dried. The first coating liquid contains, for example, a prepolymer or a polymer, and a solvent.

[0041] The synthetic resin for forming the base material layer 11 may be, for example, a polyurethane resin. The polyurethane resin may be an aqueous polyurethane. This makes it possible to obtain the base material layer 11 having high suitability for application to skin. The thickness of the base material layer 11 may be, for example, 5 µm or more and 30 µm or less.

[0042] The thin base material layer 11 made of a polyurethane resin stretches well even when a small external force is applied to the base material layer 11 to stretch the base material layer 11. Therefore, the base material layer 11 can have high conformability to the nipple which is the application target of the sheet main body 10B, and can also have high adhesiveness to the nipple.

[0043] The thickness of the base layer 11 may be, for example, 5 μm or more and 30 μm or less. The tensile elongation at break of the base layer 11 may be, for example, 130% or more. The tensile elongation at break can be determined in accordance with JIS K 7161-1:2014 (ISO 527-1:2012) "Plastics - Determination of tensile properties - Part 1: General rules" and JIS K 7127:1999 (ISO 527-3:1995) "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets". If the object to be measured does not have a yield point, the tensile fracture strain is measured, and if it has a yield point, the nominal strain at tensile fracture is measured, and the tensile elongation at break can be determined using these measured values.

[0044] Furthermore, the 100% elongation tensile strength of the base layer 11 may be, for example, 4 N / cm or less. The 100% elongation tensile strength is the value obtained by dividing the magnitude of the force measured when the strain, as defined in JIS K 7161-1:2014 (ISO 527-1:2012) "Plastics - Determination of tensile properties - Part 1: General rules", reaches a specified value (100%) by the width of the test piece. The 100% elongation tensile strength (T) (N / cm) can be calculated by the following formula.

[0045] T = F / W In the above formula, F is the magnitude of the measured force (N), and W is the width of the test specimen (cm).

[0046] The base layer 11 may be formed from a synthetic resin other than polyurethane resin. Examples of synthetic resins other than polyurethane resin include polyvinylidene fluoride resin, ethylene-vinyl acetate copolymer resin, polypropylene resin, and polyethylene terephthalate resin.

[0047] As shown in Figure 6, the process for producing the adhesive layer 12 includes an acidic aqueous solution preparation step (step S21), a second coating solution preparation step (step S22), a second coating film formation step (step S23), and a drying step (step S24). Specifically, in the acidic aqueous solution preparation step, an acidic aqueous solution containing chitosan is prepared (step S21). Next, in the second coating solution preparation step, a second coating solution for forming the adhesive layer 12 is prepared using an acidic aqueous solution containing the main component of the adhesive for forming the adhesive layer 12, a curing agent for the adhesive, and chitosan (step S22). At this time, the second coating solution is prepared so as to satisfy the above-mentioned conditions 3 and 4.

[0048] Since the second coating solution is prepared using an acidic aqueous solution containing chitosan, it is possible to ensure a uniform distribution of chitosan molecules within the second coating solution. As a result, chitosan molecules are uniformly distributed even in the adhesive layer formed using the second coating solution. The second coating solution may contain a solvent other than the acidic aqueous solution. In this case, the viscosity of the second coating solution can be adjusted using a solvent other than the acidic aqueous solution.

[0049] Thus, the adhesive layer 12 is formed by mixing an acidic aqueous solution containing chitosan with the main agent and curing agent contained in the adhesive. Chitosan is soluble in acidic aqueous solutions, and in acidic aqueous solutions, the amino groups of chitosan have a positive charge, which allows chitosan to have antibacterial activity. Since the formation of the adhesive layer 12 uses chitosan dissolved in an acidic aqueous solution that has antibacterial activity, the adhesive layer 12 can contain chitosan that has antibacterial activity. The acidic aqueous solution used to dissolve the chitosan powder contains a saturated carboxylic acid. The number of carbon atoms in the hydrocarbon chain of the saturated carboxylic acid may be between 1 and 3. Examples of saturated carboxylic acids with 1 to 3 carbon atoms in the hydrocarbon chain may be acetic acid, propionic acid, butyric acid, etc.

[0050] Next, in the second coating film formation step, a second coating film is formed on one surface of the release layer 14 using the second coating liquid (step S23). Subsequently, the second coating film is dried in the drying step to obtain an adhesive layer 12 from the second coating film (step S24). This provides an adhesive layer 12 that satisfies the above-described conditions 1 and 2. The thickness of the adhesive layer 12 may be, for example, 5 μm or more and 30 μm or less. This provides a second laminate composed of the release layer 14 and the adhesive layer 12.

[0051] The release layer 14 may be configured such that the peel strength between the release layer 14 and the adhesive layer 12 is less than the peel strength between the protective layer 13 and the base layer 11. The release layer 14 is made of a synthetic resin. The release layer 14 is made of, for example, a base sheet and a release layer. The release layer is laminated on the base sheet. When the release layer 14 comprises a base sheet and a release layer, the release layer is in contact with the adhesive layer 12. The base sheet may be made of, for example, polyethylene terephthalate resin. The base sheet may be a uniaxially oriented sheet, a biaxially oriented sheet, or an unoriented sheet. The release layer may be made of, for example, a silicone resin.

[0052] The release layer 14 may consist only of the base sheet described above. In this case, the contact surface of the base sheet that comes into contact with the adhesive surface 12S of the adhesive layer 12 may be processed to facilitate the peeling of the adhesive layer 12 from the base sheet. The processing of the contact surface of the base sheet may be, for example, embossing. The thickness of the release layer 14 may be, for example, 12 μm or more and 350 μm or less.

[0053] As described above, the adhesive layer 12 is formed from a two-component adhesive. The two-component adhesive may be, for example, an acrylic adhesive or a urethane adhesive. The thickness of the adhesive layer 12 may be, for example, 5 μm or more and 30 μm or less.

[0054] Chitosan may be in powder form. The maximum particle size of the chitosan may be, for example, 50 μm or less. From the viewpoint of suppressing the recovery of chitosan on the plate used for coating the second coating film, it is preferable that the maximum particle size of the chitosan is smaller than the thickness of the second coating film before drying. From the viewpoint of making it easier for the chitosan contained in the adhesive layer 12 to come into contact with the papillae, it is preferable that the maximum particle size of the chitosan is larger than the thickness of the adhesive layer 12 formed by the drying of the second coating film. The maximum particle size of the chitosan can be determined, for example, by the size of the mesh of the sieve used to separate the chitosan.

[0055] As shown in Figure 7, the process of obtaining a mastitis prevention sheet 10 from a first laminate and a second laminate includes a bonding step (step S31) and an aging step (step S32). Specifically, in the bonding step, the adhesive layer 12 of the second laminate is bonded to the base layer 11 of the first laminate (step S31). Next, in the aging step, the laminate composed of the first laminate and the second laminate is aged (step S32). This allows a mastitis prevention sheet 10 to be obtained. In the obtained mastitis prevention sheet 10, the protective layer 13, base layer 11, adhesive layer 12, and release layer 14 are laminated in the order described above.

[0056] [How to use the mastitis prevention sheet] The method of using the mastitis prevention sheet 10 will be explained with reference to Figures 8 to 11. Below, the method of using the mastitis prevention sheet 10 when attaching it to the teats of a dairy cow, which is an example of livestock, will be explained.

[0057] As shown in Figure 8, when using the mastitis prevention sheet 10, after peeling off the release layer 14 from the adhesive layer 12, a portion of the adhesive surface 12S is attached to the teat N of the dairy cow C. This positions the mastitis prevention sheet 10 relative to the teat N.

[0058] Next, as shown in Figure 9, the mastitis prevention sheet 10 is folded so that the adhesive surface 12S of the mastitis prevention sheet 10 surrounds the nipple N, thereby bringing the first portion 12S1 of the adhesive surface 12S into close contact with the second portion 12S2 of the adhesive surface 12S. This attaches the mastitis prevention sheet 10 to the nipple N so that the flat mastitis prevention sheet 10 has a cylindrical shape that surrounds the nipple N. The contact area formed by bringing the first portion 12S1 of the adhesive surface 12S into close contact with the second portion 12S2 is easily located outside the nipple N in the radial direction of the nipple N, and is not easily located below the nipple opening NA. Therefore, the contact area is less likely to come into contact with the milk secreted from the nipple opening NA.

[0059] Next, as shown in Figure 10, the protective layer 13 is peeled off from the base layer 11. At this time, for example, the user of the mastitis prevention sheet 10 grasps the first region 13R1 of the protective layer 13. Then, the user pulls the protective layer 13 along the direction from the first region 13R1 to the second region 13R2, tearing it from the cut 13B, thereby peeling a part of the protective layer 13 off from the base layer 11. The user also peels off the portion of the protective layer 13 that remains attached to the base layer 11. After peeling the protective layer 13 off the base layer 11, it is preferable to grasp the tubular portion of the mastitis prevention sheet 10 that surrounds the nipple N, thereby making the tubular portion adhere closely to the nipple N.

[0060] As shown in Figure 11, the third portion 12S3 of the adhesive surface 12S is brought into close contact with the fourth portion 12S4 of the adhesive surface 12S at a position away from the nipple opening NA of the nipple N, so as to seal the cylindrical end 10TE of the sheet body 10B of the mastitis prevention sheet 10. In this way, the mastitis prevention sheet 10 is attached to the nipple N so that it has a cylindrical shape surrounding the nipple N. As a result, the adhesive portion formed by the second portion 12S2 being in close contact with the first portion 12S1 of the adhesive surface 12S does not easily spread milk secreted from the nipple opening NA, making it difficult for the adhesive layer 12 to peel off the nipple N. Therefore, the sheet body 10B of the mastitis prevention sheet 10 is less likely to peel off the nipple N.

[0061] Furthermore, when sealing the cylindrical end 10TE of the sheet body 10B, the adhesive portion formed by bringing the first portion 12S1 of the adhesive surface 12S into close contact with the second portion 12S2 may be wrapped around the nipple N. This prevents the adhesive portion from protruding along the radial direction of the nipple N, thus preventing it from getting caught on obstacles, for example. This also prevents the sheet body 10B from coming off the nipple N.

[0062] When attaching the mastitis prevention sheet 10 shown in Figure 3 to the nipple N, the nipple N is positioned in the center of the mastitis prevention sheet 10 in the first direction D1. Then, the adhesive layer 12 of the mastitis prevention sheet 10 is wrapped around the nipple N, and subsequently, the protective layer 13 is removed from the base layer 11.

[0063] Furthermore, when attaching the mastitis prevention sheet 10 shown in Figure 4 to the nipple N, the nipple N is positioned relative to the mastitis prevention sheet 10 such that the slit 10C is located below the nipple N in the second direction D2. Next, the mastitis prevention sheet 10 is wrapped around the nipple N, and the cylindrical end including the slit 10C is closed. Then, the first region 13R1 of the protective layer 13 is grasped, and the protective layer 13 is removed from the base layer 11 along the slit 13C.

[0064] As described above, according to the first embodiment of the mastitis prevention sheet and the method for manufacturing the mastitis prevention sheet, the following effects can be obtained: (1) Even when the mastitis prevention sheet 10 is used under high temperature and high humidity conditions, it is possible to suppress the inactivation of the antibacterial effect of the mastitis prevention sheet 10.

[0065] [Second Embodiment] A second embodiment of the mastitis prevention sheet and a method for manufacturing the mastitis prevention sheet will be described with reference to Figures 1 to 11. In the second embodiment, the acidic compound contained in the adhesive layer 12 is different from that of the first embodiment. Therefore, while these differences will be explained below, components in the second embodiment that are common to the first embodiment will be denoted by the same reference numerals, and detailed descriptions of such components will be omitted.

[0066] [Mastitis Prevention Sheet] Referring to FIGS. 1 to 4, the mastitis prevention sheet 10 will be described. As shown in FIG. 1, the mastitis prevention sheet 10 of the present embodiment includes a base material layer 11, an adhesive layer 12, a protective layer 13, and a release layer 14, similarly to the mastitis prevention sheet 10 of the first embodiment. The adhesive layer 12 contains chitosan, hydroxycarboxylic acid, and a cured product of an adhesive for forming the adhesive layer 12.

[0067] The adhesive layer 12 satisfies the following conditions. (Condition 5) The percentage of the mass of chitosan relative to the mass of the main agent of the adhesive in the cured product of the adhesive is 3% by mass or more. (Condition 6) The percentage of the mass of hydroxycarboxylic acid relative to the mass of the main agent of the adhesive in the cured product of the adhesive is 3% by mass or more.

[0068] According to the mastitis prevention sheet 10, similarly to the mastitis prevention sheet 10 of the first embodiment, even when the mastitis prevention sheet 10 is used under high temperature and high humidity conditions, deactivation of the antibacterial effect by the mastitis prevention sheet 10 can be suppressed. The mastitis prevention sheet 10 does not lose its antibacterial effect even when left standing for two weeks in a high temperature and high humidity environment having, for example, a temperature of 40° C. and a relative humidity of 90%.

[0069] The number of carbon atoms in the hydrocarbon chain of hydroxycarboxylic acid, that is, the number of carbon atoms excluding the carbon contained in the carboxyl group (COOH) included in hydroxycarboxylic acid, may be 2 or more and 5 or less. Examples of hydroxycarboxylic acids having 2 or more and 5 or less carbon atoms in the hydrocarbon chain include lactic acid (CH ３ CH-(OH)COOH), glyceric acid (CH ２ (OH)CH(OH)-COOH), hydroxybutyric acid (CH ３ CH(OH)CH ２ -COOH), malic acid (HOOC-CH(OH)CH ２ -COOH), tartaric acid (HOOC-CH(OH)CH(OH)-COOH), citric acid (C(OH)(CH ２ COOH) ２ -COOH), isocitric acid (HOOC-CH ２ CH(COOH)CH(OH)-COOH) and the like.

[0070] The adhesive is a two-component adhesive, consisting of a main component and a curing agent. The adhesive may be, for example, an acrylic adhesive or a urethane adhesive. A urethane adhesive is preferred.

[0071] The outer edge 10E of the mastitis prevention sheet 10 and the shape of each layer may be rectangular as shown in Figure 2, trapezoidal as shown in Figure 3, or roughly rectangular as shown in Figure 4. In addition, the outer edge 10E and each layer may have polygonal shapes other than quadrilaterals, or they may have circular or elliptical shapes.

[0072] [Method for Manufacturing a Mastitis Prevention Sheet] The method for manufacturing a mastitis prevention sheet 10 will be described with reference to Figures 5 to 7. The method for manufacturing a mastitis prevention sheet 10 is the same as the method for manufacturing a first embodiment, and includes forming a base layer 11, forming an adhesive layer 12, and laminating the adhesive layer 12 to the base layer 11.

[0073] Forming the adhesive layer 12 includes preparing the coating solution to satisfy the following conditions: (Condition 7) The percentage of chitosan by mass relative to the solid content in the main component of the adhesive for forming the adhesive layer 12 is 3% by mass or more. (Condition 8) The percentage of hydroxycarboxylic acid by mass relative to the solid content of the main component is 3% by mass or more.

[0074] The method for manufacturing the mastitis prevention sheet 10 in this embodiment may include the steps shown in Figures 5 to 7, similar to the manufacturing method in the first embodiment. In this embodiment, a second coating solution satisfying conditions 7 and 8 is prepared in steps S21 and S22 shown in Figure 6. The number of carbon atoms in the hydrocarbon chain of the hydroxycarboxylic acid may be 2 or more and 5 or less. Examples of hydroxycarboxylic acids with 2 or more and 5 or less carbon atoms in the hydrocarbon chain may be lactic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citric acid, isocitric acid, etc.

[0075] [How to use the mastitis prevention sheet] The mastitis prevention sheet 10 of this embodiment is used in the same manner as the mastitis prevention sheet 10 of the first embodiment, as shown in Figures 8 to 11.

[0076] As described above, the effects described in (1) can also be obtained by the second embodiment of the mastitis prevention sheet and the method for manufacturing the mastitis prevention sheet.

[0077] [Third Embodiment] A third embodiment of the mastitis prevention sheet and the method for manufacturing the mastitis prevention sheet will be described with reference to Figures 1 to 11. In the third embodiment, the material contained in the adhesive layer 12 is different from that of the first embodiment. Therefore, while these differences will be explained below, components in the third embodiment that are common with the first embodiment will be denoted by the same reference numerals, and detailed explanations of such components will be omitted.

[0078] [Mastitis Prevention Sheet] The mastitis prevention sheet 10 will be described with reference to Figures 1 to 4. As shown in Figure 1, the mastitis prevention sheet 10 of this embodiment, like the mastitis prevention sheet 10 of the first embodiment, comprises a base layer 11, an adhesive layer 12, a protective layer 13, and a release layer 14. The adhesive layer 12 contains chitosan, an acidic compound, a cured product of an adhesive for forming the adhesive layer 12, and alcohol.

[0079] The adhesive layer 12 satisfies the following conditions: (Condition 9) The percentage of chitosan by mass relative to the mass of the main component of the adhesive in the cured adhesive is 3% by mass or more. (Condition 10) The percentage of saturated carboxylic acid by mass relative to the mass of the main component of the adhesive in the cured adhesive is 1.5% by mass or more. (Condition 11) The percentage of alcohol by mass relative to the mass of the main component of the adhesive in the cured adhesive is 40% by mass or more.

[0080] The mastitis prevention sheet 10, like the mastitis prevention sheet 10 of the first embodiment, can suppress the deactivation of the antibacterial effect of the mastitis prevention sheet 10 even when used under high temperature and high humidity conditions. For example, the mastitis prevention sheet 10 does not lose its antibacterial effect even when left undisturbed for two weeks in a high temperature and high humidity environment where the temperature is 40°C and the relative humidity is 90%.

[0081] The number of carbon atoms in the hydrocarbon chain of a saturated carboxylic acid may be between 1 and 3. Examples of carboxylic acids with 1 to 3 carbon atoms in the hydrocarbon chain are acetic acid, propionic acid, and butyric acid. The acidic compound is preferably acetic acid.

[0082] The alcohol may be a monohydric alcohol or a polyhydric alcohol. The monohydric alcohol may be a primary alcohol, a secondary alcohol, or a tertiary alcohol. Glycerin is preferred as the alcohol.

[0083] The adhesive is a two-component adhesive, consisting of a main component and a curing agent. The adhesive may be, for example, an acrylic adhesive or a urethane adhesive. A urethane adhesive is preferred.

[0084] The outer edge 10E of the mastitis prevention sheet 10 and the shape of each layer may be rectangular as shown in Figure 2, trapezoidal as shown in Figure 3, or roughly rectangular as shown in Figure 4. Furthermore, the outer edge 10E and each layer may have polygonal shapes other than quadrilaterals, or they may have circular or elliptical shapes.

[0085] [Method for Manufacturing a Mastitis Prevention Sheet] The method for manufacturing a mastitis prevention sheet 10 will be described with reference to Figures 5 to 7. The method for manufacturing a mastitis prevention sheet 10 is the same as the method for manufacturing a first embodiment, and includes forming a base layer 11, forming an adhesive layer 12, and laminating the adhesive layer 12 to the base layer 11.

[0086] Forming the adhesive layer 12 includes preparing the coating solution to satisfy the following conditions: (Condition 12) The percentage of chitosan by mass relative to the solid content in the main component of the adhesive for forming the adhesive layer 12 is 3% by mass or more. (Condition 13) The percentage of saturated carboxylic acid by mass relative to the solid content of the main component is 1.5% by mass or more. (Condition 14) The percentage of alcohol by mass relative to the solid content of the main component is 40% by mass or more.

[0087] The method for manufacturing the mastitis prevention sheet 10 in this embodiment may include the steps shown in Figures 5 to 7, similar to the manufacturing method in the first embodiment. In this embodiment, a second coating solution satisfying conditions 12 to 14 is prepared in steps S21 and S22 shown in Figure 6. The number of carbon atoms in the hydrocarbon chain of the saturated carboxylic acid may be 1 or more and 3 or less. Carboxylic acids with a hydrocarbon chain of 1 or more and 3 or less include acetic acid, propionic acid, and butyric acid.

[0088] [How to use the mastitis prevention sheet] The mastitis prevention sheet 10 of this embodiment is used in the same manner as the mastitis prevention sheet 10 of the first embodiment, as shown in Figures 8 to 11.

[0089] As described above, the effects described in (1) can also be obtained by the third embodiment of the mastitis prevention sheet and the method for manufacturing the mastitis prevention sheet.

[0090] [Examples] Examples and comparative examples will be described with reference to Figure 12. [Example 1] A biaxially oriented polypropylene (OPP) film (Futamura Chemical Co., Ltd., FOR-MP) was prepared as a protective layer 13, in which one of a pair of opposing surfaces in the thickness direction was a matte surface. Then, an aqueous polyurethane (Takelac WS-6021) (Takelac is a registered trademark) containing an ether-based polyol, which was the first coating liquid, was applied to the matte surface of the OPP film to form a first coating film. Next, the first coating film was dried to obtain a dried first coating film with a thickness of 15 μm. Subsequently, the dried first coating film was aged at room temperature for 48 hours to obtain a base layer 11. This obtained a first laminate composed of the protective layer 13 and the base layer 11.

[0091] A release film (Therapyle WZ, manufactured by Toray Film Processing Co., Ltd.) (Therapyle is a registered trademark), consisting of a polyethylene terephthalate (PET) film and a release layer, was prepared as the release layer 14. In addition, a urethane-based adhesive (manufactured by Toyo Chem Co., Ltd., SP-205), a curing agent (manufactured by Toyo Chem Co., Ltd., T-501B), and a diluent (manufactured by Toyo Ink Co., Ltd., NC401 Solvent C) were prepared. Furthermore, chitosan powder (manufactured by Hokkaido Soda Co., Ltd., chitosan powder, degree of deacetylation 83.5%, molecular weight approximately 220,000), which had been selected using a 0.6 mm sieve, was dispersed in water to obtain an aqueous chitosan solution. Next, in order to dissolve the chitosan powder, chitosan was added to an aqueous acetic acid solution to prepare an aqueous acetic acid solution containing chitosan. As a result, an aqueous solution of acetic acid containing chitosan was prepared such that the concentration of chitosan in the aqueous solution of acetic acid was 3% by mass, and the concentration of acetic acid was also 3% by mass.

[0092] Next, an aqueous acetic acid solution containing chitosan was added to the main component, and then the main component and the aqueous acetic acid solution containing chitosan were mixed. At this time, the aqueous acetic acid solution containing chitosan was added to the main component such that the percentage of chitosan's mass relative to the solid content of the main component, i.e., the mass of solids, was 6% by mass, and the percentage of acetic acid's mass relative to the solid content of the main component was 6.0% by mass. Next, the viscosity of the second mixture, which consisted of the main component, the aqueous acetic acid solution containing chitosan, and the solvent, was adjusted by adding a diluent to the first mixture of the main component and the aqueous acetic acid solution containing chitosan. Subsequently, a curing agent was added to the second mixture, and then the second mixture with the curing agent added was stirred to obtain a second coating solution for forming an adhesive layer.

[0093] Next, a second coating was obtained by applying a second coating solution to the release layer of the release film. Subsequently, an adhesive layer 12 having a thickness of 10 μm was obtained by drying the second coating. This resulted in a second laminate composed of a release layer 14 and an adhesive layer 12.

[0094] A laminate was obtained by bonding the adhesive layer 12 of the second laminate to the base layer 11 of the first laminate. The laminate had a layer structure in which a protective layer 13, a base layer 11, an adhesive layer 12, and a release layer 14 were laminated in that order. Next, the mastitis prevention sheet 10 of Example 1 was obtained by aging the laminate at 50°C for 72 hours.

[0095] [Example 2] An antimastitis sheet 10 for Example 2 was obtained in the same manner as in Example 1, except that the percentage of chitosan by mass relative to the solid content of the main component was changed to 8% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was changed to 8.0% by mass.

[0096] [Example 3] The mastitis prevention sheet 10 of Example 3 was obtained in the same manner as in Example 1, except that the percentage of chitosan by mass relative to the solid content of the main component was changed to 10% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was changed to 10.0% by mass.

[0097] [Example 4] An antimastitis sheet 10 of Example 4 was obtained in the same manner as in Example 1, except that the percentage of chitosan by mass relative to the solid content of the main component was changed to 10% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was changed to 5.0% by mass.

[0098] [Example 5] The mastitis prevention sheet 10 of Example 5 was obtained in the same manner as in Example 1, except that the percentage of acetic acid by mass relative to the solid content of the main component was changed to 3.0% by mass.

[0099] [Example 6] In Example 1, the percentage of chitosan by mass relative to the solid content of the main component was changed to 3% by mass, acetic acid was changed to citric acid, and the percentage of citric acid by mass relative to the solid content of the main component was set to 9.0% by mass. Otherwise, the mastitis prevention sheet 10 of Example 6 was obtained in the same manner as in Example 1.

[0100] [Example 7] In Example 6, acetic acid was added along with citric acid, and the percentage of citric acid by mass relative to the solid content of the main component was set to 4.5% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was set to 1.5% by mass. Otherwise, the mastitis prevention sheet 10 of Example 7 was obtained by the same method as in Example 6.

[0101] [Example 8] The mastitis prevention sheet 10 of Example 8 was obtained in the same manner as in Example 6, except that citric acid was replaced with lactic acid and the percentage of lactic acid by mass relative to the solid content of the main ingredient was set to 3% by mass.

[0102] [Example 9] In Example 1, the percentage of chitosan by mass relative to the solid content of the main component was changed to 3% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was changed to 1.5% by mass. Also, when obtaining the first mixture, the main component, the aqueous acetic acid solution containing chitosan, and glycerin were mixed so that the percentage of glycerin by mass relative to the solid content of the main component was 40% by mass. Otherwise, the mastitis prevention sheet 10 of Example 9 was obtained in the same manner as in Example 1.

[0103] [Comparative Example 1] A mastitis prevention sheet 10 for Comparative Example 1 was obtained in the same manner as in Example 1, except that the percentage of chitosan by mass relative to the solid content of the main component was changed to 3% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was changed to 1.5% by mass.

[0104] [Comparative Example 2] A mastitis prevention sheet 10 for Comparative Example 2 was obtained in the same manner as in Example 1, except that the percentage of chitosan by mass relative to the solid content of the main component was changed to 3% by mass, and the percentage of acetic acid by mass relative to the solid content of the main component was changed to 3.0% by mass.

[0105] [Comparative Example 3] In Comparative Example 2, when obtaining the first mixture, the main component, an aqueous acetic acid solution containing chitosan, and glycerin were mixed so that the percentage of glycerin by mass relative to the solid content of the main component was 5% by mass. Otherwise, the mastitis prevention sheet 10 of Comparative Example 3 was obtained in the same manner as in Comparative Example 2.

[0106] [Comparative Example 4] A mastitis prevention sheet 10 for Comparative Example 4 was obtained in the same manner as in Comparative Example 3, except that the percentage of glycerin by mass relative to the solid content of the main ingredient was changed to 10% by mass.

[0107] [Comparative Example 5] A mastitis prevention sheet 10 for Comparative Example 5 was obtained in the same manner as in Comparative Example 3, except that the percentage of glycerin by mass relative to the solid content of the main ingredient was changed to 20% by mass.

[0108] [Evaluation Method] [100% Modulus] The 100% modulus, i.e., the 100% elongation tensile stress, was measured according to the methods specified in JIS K7127:1999 (ISO 527-3:1995) "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets" and JIS K7161-1:2014 (ISO 527-1:2012) "Plastics - Determination of tensile properties - Part 1: General rules". The 100% modulus was calculated as the stress when the strain reached 100%. For this test, an Autograph testing machine (manufactured by Shimadzu Corporation, Autograph AGS-X 5kN load cell 1kN) (Autograph is a registered trademark) was used as the tensile testing machine, and the test speed was set to 300 mm / min.

[0109] [Antibacterial Effect] For each example and comparative example of the mastitis prevention sheet, the antibacterial activity value against Escherichia coli was measured using a method compliant with JIS Z 2801:2010 "Antibacterial processed products - Antibacterial test methods and antibacterial effects". At this time, the antibacterial activity value on the adhesive surface of each mastitis prevention sheet was measured.

[0110] For each example and comparative example of the mastitis prevention sheet, the antibacterial activity value was measured after being left standing at room temperature for two weeks, and after being left standing in an environment of 40°C and 90% relative humidity for two weeks. Room temperature was defined as 25°C, and the relative humidity at room temperature was set to 40%. The environment of 40°C and 90% relative humidity simulated a hot and humid environment such as that of summer.

[0111] Furthermore, the antibacterial effect of each mastitis prevention sheet after being left in a high-temperature, high-humidity environment was evaluated in the following two stages: A: The antibacterial activity value was 2.0 or higher, indicating that the mastitis prevention sheet has an antibacterial effect. B: The antibacterial activity value was less than 2.0, indicating that the mastitis prevention sheet does not have an antibacterial effect.

[0112] [Evaluation Results] The evaluation results for the mastitis prevention sheets of each example and comparative example are shown in Figure 12. As shown in Figure 12, the 100% modulus was found to be 1.3 MPa in Examples 1, 2, 4, 6, 7, and Comparative Example 1, and 1.8 MPa in Example 3. The 100% modulus was found to be 1.2 MPa in Examples 5 and 8, and 0.1 MPa in Example 9 and Comparative Example 5. The 100% modulus was found to be 1.9 MPa in Comparative Example 2, 0.6 MPa in Comparative Example 3, and 0.4 MPa in Comparative Example 4.

[0113] The antibacterial activity values ​​after standing at room temperature were 5.8 in Example 1, 6.0 in Examples 2 and 4, 5.6 in Example 3, and 5.3 in Example 5. The antibacterial activity values ​​after standing at room temperature were 4.6 in Example 6, 5.4 in Example 7, 6.8 in Example 8, and 7.0 in Example 9. The antibacterial activity values ​​after standing at room temperature were 3.9 in Comparative Example 1, 5.9 in Comparative Example 2, 4.6 in Comparative Example 3, 5.7 in Comparative Example 4, and 5.4 in Comparative Example 5. Thus, when each mastitis prevention sheet was left at room temperature, it was found that all examples and all comparative examples of mastitis prevention sheets had an antibacterial effect.

[0114] The antibacterial activity values ​​after standing in high temperature and humidity conditions were found to be 5.8 in Examples 1 and 5, 6.4 in Example 2, and 7.0 in Examples 3 and 4. The antibacterial activity values ​​after standing in high temperature and humidity conditions were found to be 3.5 in Example 6, 2.5 in Example 7, 3.8 in Example 8, and 6.2 in Example 9. The antibacterial activity values ​​after standing in high temperature and humidity conditions were found to be 0.2 in Comparative Example 1, 0.9 in Comparative Example 2, 0.0 in Comparative Example 3, and 0.5 in Comparative Examples 4 and 5. In other words, the antibacterial effect in all examples was "A", while the antibacterial effect in all comparative examples was "B".

[0115] Thus, it was found that the mastitis prevention sheets of Examples 1 to 9 retained their antibacterial effect even after being left in high temperature and high humidity conditions for two weeks. In contrast, the mastitis prevention sheets of Comparative Examples 1 to 5 retained their antibacterial effect unless left in high temperature and high humidity conditions for a long period of time, but their antibacterial effect was lost after being left in high temperature and high humidity conditions for two weeks.

[0116] [Examples of Modifications] Each embodiment described above can be modified and implemented as follows: [Nonwoven Fabric Layer] The mastitis prevention sheet of each embodiment may be provided with a nonwoven fabric layer instead of the protective layer 13. As shown in Figure 13, the mastitis prevention sheet 20 comprises a sheet body 20B and a release layer 14. The sheet body 20B comprises a base layer 11, a first adhesive layer 22, a second adhesive layer 25, and a nonwoven fabric layer 23. In the thickness direction of the sheet body 20B, the base layer 11 is sandwiched between the first adhesive layer 22 and the second adhesive layer 25. The nonwoven fabric layer 23 is located on the opposite side of the base layer 11 from the second adhesive layer 25. As a result, the second adhesive layer 25 adheres the nonwoven fabric layer 23 to the surface of the base layer 11 opposite to the surface in contact with the first adhesive layer 22.

[0117] Figures 14 to 18 each show a step in the manufacturing method of the mastitis prevention sheet 20. As shown in Figure 14, when manufacturing the mastitis prevention sheet 20, first a protective layer 13 is prepared. Next, a first coating film is formed on one of a pair of opposing surfaces of the protective layer 13 in the thickness direction using a first coating liquid. After drying the first coating film, the base layer 11 is obtained by aging the first coating film.

[0118] As shown in Figure 15, after preparing the release layer 14, a second coating film is formed on one of a pair of opposing surfaces of the release layer 14 in the thickness direction using the second coating liquid. By drying the second coating film, the first adhesive layer 22 is obtained.

[0119] Then, as shown in Figure 16, by bonding the first adhesive layer 22 to the base layer 11, a first laminate is obtained in which the release layer 14, the first adhesive layer 22, the base layer 11, and the protective layer 13 are laminated in the order described above.

[0120] Next, a third coating solution for forming the second adhesive layer 25 is prepared. The third coating solution contains the main component and curing agent of the adhesive for forming the second adhesive layer 25. The third coating solution may also contain a diluent.

[0121] Then, as shown in Figure 17, after preparing the release layer 26, a third coating is formed on one of a pair of opposing surfaces of the release layer 26 in the thickness direction. Subsequently, the second adhesive layer 25 is obtained by drying the third coating.

[0122] Then, as shown in Figure 18, by laminating the nonwoven fabric layer 23 to the second adhesive layer 25, a second laminate is obtained in which the release layer 26, the second adhesive layer 25, and the nonwoven fabric layer 23 are laminated in the order described above.

[0123] In the first laminate, the protective layer 13 is peeled off from the base layer 11, and in the second laminate, the release layer 26 is peeled off from the second adhesive layer 25, after which the second adhesive layer 25 is attached to the base layer 11. Then, the laminate, in which the release layer 14, the first adhesive layer 22, the base layer 11, the second adhesive layer 25, and the nonwoven fabric layer 23 are laminated in the order described above, is aged at 50°C for 72 hours. This makes it possible to obtain a mastitis prevention sheet 20.

[0124] When using the mastitis prevention sheet 20, first, the release layer 14 is removed from the first adhesive layer 22. Next, the first adhesive layer 22 is attached to, for example, the udder of a dairy cow, and then the sheet body 20A is wrapped around the teat.

[0125] Because the mastitis prevention sheet 20 includes a nonwoven fabric layer 23, it is less stretchable than the mastitis prevention sheet 10 of each embodiment.

[0126] [How to use the mastitis prevention sheet] The mastitis prevention sheet 10 may be attached to the nipple N by the following method. First, as shown in Figure 6, a part of the mastitis prevention sheet 10 is positioned on the nipple N. Next, while wrapping the mastitis prevention sheet 10 around the nipple N, the protective layer 13 is peeled off from the base layer 11. Of the base layer 11, the surface that is in contact with the adhesive layer 12 and from which the protective layer 13 has been peeled off is the surface to be adhered. The first part of the adhesive surface 12S of the adhesive layer 12 is brought into close contact with the first part of the surface to be adhered to the base layer 11, thereby making it possible to attach the sheet body 10B to the nipple N in a tubular shape that surrounds the nipple N.

[0127] According to the method of use described above, the adhesive portion formed by the first portion of the adhesive surface 12S adhering tightly to the first portion of the surface to be adhered to is less likely to be spread by milk secreted from the nipple opening, and therefore the adhesive layer 12 is less likely to peel off from the nipple N.

Claims

1. A mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer, wherein the adhesive layer comprises chitosan, a saturated carboxylic acid, and a cured product of an adhesive for forming the adhesive layer, wherein the percentage of the mass of the chitosan in the cured product of the adhesive is 6% by mass or more relative to the mass of the main component of the adhesive, and the percentage of the mass of the saturated carboxylic acid relative to the mass of the main component is 3% by mass or more.

2. The mastitis prevention sheet according to claim 1, wherein the number of carbon atoms in the hydrocarbon chain of the saturated carboxylic acid is 1 or more and 3 or less.

3. A mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer, wherein the adhesive layer comprises chitosan, a hydroxycarboxylic acid, and a cured product of an adhesive for forming the adhesive layer, wherein the percentage of the mass of the chitosan in the cured product of the adhesive to the mass of the main component of the adhesive is 3% by mass or more, and the percentage of the mass of the hydroxycarboxylic acid to the mass of the main component is 3% by mass or more.

4. The mastitis prevention sheet according to claim 3, wherein the number of carbon atoms in the hydrocarbon chain of the hydroxycarboxylic acid is 2 or more and 5 or less.

5. A mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer, wherein the adhesive layer comprises chitosan, a saturated carboxylic acid, a cured product of an adhesive for forming the adhesive layer, and an alcohol, wherein the percentage of the mass of the chitosan in the cured product of the adhesive is 3% by mass or more relative to the mass of the main component of the adhesive, the percentage of the mass of the saturated carboxylic acid relative to the mass of the main component is 1.5% by mass or more, and the percentage of the mass of the alcohol relative to the mass of the main component is 40% by mass or more.

6. The mastitis prevention sheet according to claim 5, wherein the alcohol is glycerin.

7. A method for manufacturing a mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer, comprising: forming the base layer; forming the adhesive layer; and laminating the adhesive layer to the base layer, wherein forming the adhesive layer involves preparing a coating solution containing the main component, the chitosan, and the saturated carboxylic acid such that the percentage of chitosan by mass relative to the solid content of the main component of the adhesive for forming the adhesive layer is 6% by mass or more, and the percentage of saturated carboxylic acid by mass relative to the solid content of the main component is 3% by mass or more.

8. A method for manufacturing a mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer, comprising: forming the base layer; forming the adhesive layer; and laminating the adhesive layer to the base layer, wherein forming the adhesive layer involves preparing a coating solution containing the main component, the chitosan, and the hydroxycarboxylic acid such that the percentage of chitosan by mass relative to the solid content of the main component of the adhesive for forming the adhesive layer is 3% by mass or more, and the percentage of hydroxycarboxylic acid by mass relative to the solid content of the main component is 3% by mass or more.

9. A method for manufacturing a mastitis prevention sheet comprising a base layer and an adhesive layer supported by the base layer, comprising: forming the base layer; forming the adhesive layer; and laminating the adhesive layer to the base layer, wherein forming the adhesive layer involves preparing a coating solution containing the main component, the chitosan, the saturated carboxylic acid, and the alcohol such that the percentage of chitosan by mass relative to the solid content of the main component of the adhesive for forming the adhesive layer is 3% by mass or more, the percentage of saturated carboxylic acid by mass relative to the solid content of the main component is 1.5% by mass or more, and the percentage of alcohol by mass relative to the solid content of the main component is 40% by mass or more.

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