Core-shell structure microspheres for indicating pet urine pH, variable-color urine pads for pets, and methods for manufacturing the same.

Abstract

To improve the stability of color change in variable-color urine pads for pets. [Solution] The urine pad comprises a nonwoven fabric layer (polypropylene nonwoven fabric containing core-shell structure microspheres), a fast-absorbing layer (absorbent gel), and a leak-proof layer (PE film). The core-shell structure microspheres consist of a shell layer made of low-melting-point polyester with a melting point of 80-120°C, and a core layer made of hollow microspheres of acrylamide-acrylic acid copolymer, with anthocyanins adsorbed on the core layer. The nonwoven fabric layer, fast-absorbing layer, and leak-proof layer are heat-pressed and fixed at 120-150°C, and the edges of the materials are further pressed with ultrasound to obtain a variable-color urine pad for pets.

Description

Technical Field

[0001] The present invention relates to core-shell structured microspheres for indicating the urine pH of pets, variable-color urine pads for pets, and methods for manufacturing them.

Background Art

[0002] Cats belong to carnivores and generally produce acidic urine with a pH value of 5.5 to 7.5 and an optimal range of approximately 6 to 6.5 in a healthy state with a natural diet. Diet and disease are the most important factors affecting the urine pH value of cats, and taking drugs, stress, intense exercise, etc. also cause fluctuations in the urine pH of cats. Most pet cats raised at home mainly ingest commercially available cat food, and the vegetable and grain components contained therein increase the urine pH. In addition, the low water intake when ingesting dry food also causes the urine pH to tend to be alkaline. Some cats raised on raw food have a high intake of meat and their urine pH tends to be acidic.

[0003] Furthermore, many diseases in cats are accompanied by a deviation of the urine pH from the normal range to acidic or alkaline. For example, in diseases such as metabolic or respiratory acidosis, fever, gout, emphysema, urinary calculi, kidney stones, diabetes, leukemia, etc., the urine pH tends to be acidic. In diseases such as metabolic or respiratory alkalosis, frequent vomiting, urinary retention, cystitis, urinary tract infection, renal tubular acidosis, chronic glomerulonephritis, etc., the urine pH tends to be alkaline. When a cat's urine tends to be acidic, calcium oxalate stones are likely to form, and when it tends to be alkaline, ammonium phosphate crystals are likely to precipitate and struvite stones are formed. When stones are formed, it causes inflammation in the urinary tract, bladder, and kidneys, and in severe cases, it leads to urinary tract obstruction, hematuria, difficulty in urination, and poses a risk to life. Therefore, the abnormality of the urine pH value of cats can, to a certain extent, be an indicator of specific potential diseases, especially feline urinary system diseases and kidney diseases. Therefore, by measuring the urine pH value of cats, potential health problems can be detected early, and appropriate measures can be taken to maintain the health status of cats.

[0004] To prevent cat waste from soiling the floor, urine pads are typically used. Therefore, designing urine pads with a pH-indicating color-changing structure allows for immediate observation of the acid-base balance of the cat's urine, thereby assisting in assessing its health. Chinese Patent Application Publication No. 116762712 discloses a functional urine pad for pets. This pad has a structure in which, from top to bottom, a non-woven fabric layer, a special ink-printed area, a polymer absorbent layer, and a waterproof / leak-proof layer are bonded together. This technical configuration utilizes the pH-based acid-base color change principle. By setting a special ink-printed area, when the pet's internal pH changes due to illness, the urine changes color upon contact with the special ink-printed area, allowing for early detection of changes due to lower urinary tract diseases and providing reference and guidance for timely treatment. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Chinese Patent Application Publication No. 116762712 Specification [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the above technical configuration, the composition of the special ink is unknown, and although it is placed between the nonwoven fabric layer and the absorbent layer, no other treatment is applied. Therefore, due to the superabsorbent properties of the absorbent layer, the ink easily penetrates into the absorbent layer along with the urine, which may affect the color expression on the surface. Thus, there is a need to provide an improved variable-color urine pad for pets to solve the above problem. [Means for solving the problem]

[0007] The object of the present invention is to provide core-shell structure microspheres for indicating the pH of pet urine, variable-color urine pads for pets, and methods for manufacturing the same. By using core-shell structure microspheres with adsorbed anthocyanins, a color change can be produced in response to different acid-base concentrations in pet urine, thereby allowing for assessment of the pet's health status. By utilizing low-melting-point polyester, adhesive strength can be increased, and its hydrophobicity can prevent the dissolution and loss of anthocyanins, thereby improving the stability of the color reaction.

[0008] To achieve the above objective, as a first aspect of the present invention, a core-shell structure microsphere for indicating pet urine pH is provided. The shell layer is a low-melting-point polyester, and the core layer is a porous water-absorbing material on which anthocyanins are adsorbed.

[0009] Furthermore, the melting point of the low-melting-point polyester is 80-120°C, and the porous water-absorbing material is a hollow microsphere of an acrylamide-acrylic acid copolymer.

[0010] As a second aspect, the present invention further provides a method for manufacturing the above-mentioned core-shell structure microsphere. This method includes the following steps:

[0011] S1: A pore-forming agent is dispersed in deionized water, and then acrylamide, acrylic acid, and potassium persulfate are added and copolymerized to obtain a complex microsphere:

[0012] S2: Remove the pore-forming agent from the composite microsphere to obtain hollow microspheres of the acrylamide-acrylic acid copolymer:

[0013] S3: A portion of the ethylene glycol is esterified with the hollow microspheres of the acrylamide-acrylic acid copolymer, and then terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol, and diethylene glycol are added to carry out an esterification reaction to obtain hollow microspheres coated with a low-melting-point polyester:

[0014] S4: Hollow microspheres coated with a low-melting-point polyester are immersed in an aqueous solution containing anthocyanin to allow adsorption, then removed and dried to obtain core-shell structure microspheres.

[0015] Furthermore, in step S1, the pore-forming agent is calcium carbonate with a particle size of 50 to 500 nm, and in step S2, the pore-forming agent is dissolved and removed with hydrochloric acid.

[0016] Furthermore, in step S1, the molar ratio of acrylamide to acrylic acid is 1:(2~3), and the copolymerization reaction temperature is 60~80°C.

[0017] Furthermore, in step S3, the catalyst used in the condensation reaction is antimony trioxide, the molar ratio of terephthalic acid, adipic acid, ethylene glycol, 2,3-pentanediol, and diethylene glycol is 1:(0.045~0.055):(1.2~1.3):(0.45~0.50):(0.10~0.12), and the molar ratio of ethylene glycol to acrylic acid is (10~30):1.

[0018] As a third aspect, the present invention provides a variable-color urine pad for pets. From top to bottom, it comprises a nonwoven fabric layer, a fast-absorbing layer, and a leak-proof layer. The nonwoven fabric layer contains the core-shell structure microspheres, or core-shell structure microspheres obtained by the manufacturing method, and produces a color change in response to differences in the acidity and baseness of the pet's urine, which is used to determine the pet's health condition.

[0019] Furthermore, the nonwoven fabric layer is a polypropylene nonwoven fabric containing the core-shell structure microspheres, the leak-proof layer is a PE (polyethylene) film, and the fast-absorbing layer is a water-absorbing gel or water-absorbing resin.

[0020] As a fourth aspect, the present invention provides a method for manufacturing the above-mentioned variable-color urine pad for pets. The method is characterized by obtaining a polypropylene composite nonwoven fabric by compound spinning a core-shell structure microsphere and polypropylene; laminating the polypropylene composite nonwoven fabric, a fast-absorbing layer and a leak-proof layer in order, fixing them with heat and pressure, and further pressing the edges of the material with ultrasound to obtain a variable-color urine pad for pets.

[0021] Furthermore, the temperature for the heat-pressure fixing is 120-150°C.

[0022] The present invention also provides a pet diaper. The diaper comprises a nonwoven fabric layer, a fast-absorbing layer, and a leak-proof layer. The nonwoven fabric layer contains the core-shell structure microspheres described above, or core-shell structure microspheres obtained by either of the above manufacturing methods, and is used to cause a color change in response to differences in the acidity / baseness of the pet's urine, thereby enabling the assessment of the pet's health.

[0023] The technical configuration of the present invention has the following main technical advantages compared to the prior art.

[0024] The variable-color urine pad for pets of the present invention consists of a core-shell structure microsphere, where the shell layer is made of low-melting-point polyester and the core layer is made of a porous, absorbent material that adsorbs anthocyanins. The interior (core layer) is more hydrophilic than the exterior (shell layer), increasing the adhesion strength of the anthocyanins within the pad, preventing dissolution and leakage due to the action of sweat and urine, improving the stability of the color reaction, and preventing color changes over time from affecting judgment. It also enhances urine absorption and allows for rapid contact with anthocyanins to develop color. The hollow structure increases the amount of anthocyanin adsorbed and improves the sensitivity of the color reaction. The exterior low-melting-point polyester is a hydrophobic material, which on the one hand increases compatibility with the nonwoven fabric, and on the other hand increases adhesive strength through heat-pressure fusion. The present invention allows for the determination of a pet's health status by causing a color change according to the difference in acidity / baseness of the pet's urine. Furthermore, by providing the core-shell structure microsphere within the nonwoven fabric layer, the color change can be immediately seen from the surface layer, preventing the color change from being obscured and delaying judgment.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 is a graph showing the change of the color difference value of Example 1, Comparative Example 1, and Comparative Example 2 with the test time.

Embodiments for Carrying out the Invention

[0026] To more clearly understand the object, technical means, and advantages of the present invention, the following examples will be combined to further explain the present invention in detail. However, the specific examples described here are only for explaining the present invention and do not limit the present invention. In addition, the technical features included in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] The present invention provides a core-shell structured microsphere used for indicating the urine pH of pets. The shell layer is a low melting point polyester, the core layer is a porous water-absorbing material, and anthocyanin is adsorbed on the core layer. The melting point of the low melting point polyester is 80 to 120 °C, and the porous water-absorbing material is a hollow microsphere of an acrylamide-acrylic acid copolymer.

[0028] By configuring in this way, the hydrophilicity inside becomes greater than that outside, enhancing the fixing strength of anthocyanin inside, preventing dissolution and leakage due to the action of sweat, urine, etc., and improving the urine adsorption property, and can quickly contact with anthocyanin to cause color development. Furthermore, the hollow structure increases the adsorption amount of anthocyanin and improves the sensitivity of color response. The outer low melting point polyester is a hydrophobic material, which on the one hand enhances the compatibility with the non-woven fabric, and on the other hand enables thermocompression fusion and can improve the adhesion strength.

[0029] The present invention also provides a method for manufacturing the above core-shell structured microsphere. This method includes the following steps:

[0030] S1, a pore-forming agent is dispersed in deionized water, and then acrylamide, acrylic acid, and potassium persulfate are added to carry out copolymerization to obtain a complex microsphere:

[0031] S2, the pore-forming agent is removed from the composite microsphere to obtain hollow microspheres of the acrylamide-acrylic acid copolymer:

[0032] S3, 1 / 2 to 1 / 5 of the total amount of ethylene glycol is esterified with the hollow microspheres of the acrylamide-acrylic acid copolymer, and then terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol, and diethylene glycol are added and esterified to obtain hollow microspheres whose surfaces are coated with a low-melting-point polyester:

[0033] S4. The hollow microspheres whose surfaces are coated with a low-melting-point polyester are immersed in an aqueous solution containing anthocyanin to allow adsorption, then removed and dried to obtain core-shell structure microspheres.

[0034] In this invention, a hollow structure is constructed using a pore-forming agent, and a hydrophilic layer is formed by copolymerization of acrylamide and acrylic acid, providing a basis for anthocyanin adsorption and introducing carboxyl groups necessary for grafting low-melting-point polyesters. Ethylene glycol is first esterified with the carboxyl groups of acrylic acid to form ethylene glycol acrylate, and then other monomers are added. The branched monomers contribute to the formation of low-melting-point polyesters and provide a basis for hot-pressure bonding.

[0035] In step S1, the pore-forming agent is calcium carbonate with a particle size of 50 to 500 nm, preferably 50 to 200 nm, and in step S2, the pore-forming agent is dissolved and removed with hydrochloric acid.

[0036] In step S1, the molar ratio of acrylamide to acrylic acid is 1:(2~3), and the copolymerization reaction temperature is 60~80°C. By adjusting the content of acrylamide and acrylic acid, the hydrophilicity and the content of low-melting-point polyester grafted onto the surface can be adjusted. If the acrylic acid content is too low, the coating effect of the low-melting-point polyester decreases, anthocyanins easily dissolve and leach out, and may penetrate into the highly absorbent, fast-absorbing layer, potentially affecting the color development effect. If the acrylic acid content is too high, hydrophilicity decreases, affecting the amount of anthocyanins retained and also affecting the color development sensitivity.

[0037] In step S3, antimony trioxide is used as the catalyst for the condensation reaction. The molar ratio of terephthalic acid, adipic acid, ethylene glycol, 2,3-pentanediol, and diethylene glycol is 1:(0.045~0.055):(1.2~1.3):(0.45~0.50):(0.10~0.12). The molar ratio of the total amount of ethylene glycol to acrylic acid is (10~30):1.

[0038] The present invention provides a variable-color urine pad for pets, comprising, from top to bottom, a nonwoven fabric layer, a fast-absorbing layer, and a leak-proof layer. The nonwoven fabric layer contains the core-shell structure microspheres described above, or core-shell structure microspheres obtained by the manufacturing method described above, and changes color according to the difference in acidity and baseness of the pet's urine, thereby allowing the health status of the pet to be determined.

[0039] Furthermore, the nonwoven fabric layer is a polypropylene nonwoven fabric containing the core-shell structure microspheres, and the content of the core-shell structure microspheres is 5% to 15% of the polypropylene mass. The leak-proof layer is a PE film, and the fast-absorbing layer is a water-absorbing gel or water-absorbing resin.

[0040] As a fourth aspect, the present invention provides a method for manufacturing the above-described variable-color urine pad for pets. A polypropylene composite nonwoven fabric is obtained by compound spinning a core-shell structure microsphere and polypropylene. The polypropylene composite nonwoven fabric, a fast-absorbing layer and a leak-proof layer are laminated in order, fixed by heat and pressure, and the edges of the material are further pressed with ultrasound to obtain a variable-color urine pad for pets. Furthermore, the temperature for the heat and pressure fixing is 120 to 150°C. [Examples]

[0041] The variable-color urine pad for pets consists of, from top to bottom, a nonwoven fabric layer (polypropylene nonwoven fabric containing core-shell structure microspheres), a fast-absorbing layer (absorbent gel), and a leak-proof layer (PE film). The manufacturing method is as follows:

[0042] A polypropylene composite nonwoven fabric is obtained by compound spinning core-shell structure microspheres and polypropylene (the amount of core-shell structure microspheres used is 8% of the mass of polypropylene). A PE film, an absorbent gel, and the polypropylene composite nonwoven fabric are laminated in order, fixed by heat and pressure at 130°C, and the edges of the material are pressed together with ultrasound to obtain a variable-color urine pad for pets.

[0043] The manufacturing method for core-shell structure microspheres is as follows:

[0044] S1: Calcium carbonate with a particle size of 150 nm is dispersed in deionized water at a mass fraction of 1%, then acrylamide, acrylic acid (molar ratio of acrylamide to acrylic acid is 1:2, and the total mass of acrylamide and acrylic acid is 10 times the mass of calcium carbonate), and potassium persulfate are added, copolymerized at 80°C, and then complex microspheres are obtained by centrifugation and drying:

[0045] S2: Remove calcium carbonate from the complex microspheres using hydrochloric acid to obtain hollow microspheres of the acrylamide-acrylic acid copolymer:

[0046] S3: One-quarter of the total amount of ethylene glycol is esterified with the acrylamide-acrylic acid copolymer hollow microspheres under the action of sulfuric acid. Then, terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol, diethylene glycol, and antimony trioxide are added and condensation polymerization is carried out to obtain hollow microspheres coated with a low-melting-point polyester: The molar ratio of terephthalic acid, adipic acid, ethylene glycol, 2,3-pentanediol, and diethylene glycol is 1:0.045:1.2:0.45:0.10, and the molar ratio of total ethylene glycol to acrylic acid is 15:1:

[0047] S4: Hollow microspheres coated with a low-melting-point polyester are immersed in an aqueous solution containing anthocyanin (red cabbage extract, commercially available) (anthocyanin mass fraction 0.5%, the mass of the hollow microspheres is 10 times the mass of the anthocyanin) to adsorb the microspheres, then removed and dried to obtain core-shell structure microspheres. [Examples]

[0048] The difference from Example 1 is that the molar ratio of acrylamide to acrylic acid is 1:1. [Examples]

[0049] The difference from Example 1 is that the molar ratio of acrylamide to acrylic acid is 1:3. [Examples]

[0050] The difference from Example 1 is that the molar ratio of total ethylene glycol to acrylic acid is 5:1. [Examples]

[0051] The difference from Example 1 is that the molar ratio of total ethylene glycol to acrylic acid is 30:1.

[0052] [Proportional Relations 1] The difference from Example 1 is that the method for manufacturing core-shell structure microspheres is as follows:

[0053] S1: Calcium carbonate with a particle size of 150 nm is dispersed in deionized water at a mass fraction of 1%, then acrylamide, acrylic acid (molar ratio of acrylamide to acrylic acid is 1:2, and the total mass of acrylamide and acrylic acid is 10 times the mass of calcium carbonate), and potassium persulfate are added, and a copolymerization reaction is carried out at 80°C. Subsequently, centrifugation and drying are performed to obtain complex microspheres.

[0054] S2: Remove calcium carbonate from the complex microspheres using hydrochloric acid to obtain hollow microspheres of the acrylamide-acrylic acid copolymer:

[0055] S3: The hollow microspheres of the acrylamide-acrylic acid copolymer are immersed and adsorbed in an aqueous solution containing anthocyanin (red cabbage extract, commercially available) (anthocyanin mass fraction 0.5%, hollow microsphere mass is 10 times the anthocyanin mass), removed and dried to obtain microspheres (without low-melting-point polyester coating).

[0056] [Proportional Relations 2] The difference from Example 1 is that calcium carbonate (pore-forming agent) was not added during the manufacturing process of the core-shell structure microsphere.

[0057] Cat urine samples were collected, and buffer solutions with pH values ​​of 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 were prepared by adding buffer. A urine pad prepared in Example 1 was taken, and 1 mL of each solution with a different pH value was added dropwise. The color development time and color change were observed, and the results are shown in Table 1. Next, 1 mL of the pH 3 solution was added dropwise to the urine pads prepared in Examples 1-5 and Proportional Ratio 1-2, and the color development time, the state of color change, and the color change after 5 minutes were observed, and the results are shown in Table 2.

[0058] [Table 1]

[0059] Table 1 shows the test results for each pH solution in Example 1. As can be seen from Table 1, the urine pad manufactured according to the present invention can produce a color change in response to different pH values, and by creating a colorimetric card based on this, users can quickly compare the results and visually observe the acid-base ratio of cat urine.

[0060] [Table 2]

[0061] Table 2 shows the test results for the examples and proportionality. As can be seen from Table 2, when the amount of acrylic acid used is reduced (Example 2), the initial color change is not significantly affected, but after being left for a certain period of time, the color becomes lighter and the distribution becomes uneven. This may be because the lower acrylic acid content reduces the amount of low-melting-point polyester grafted onto the surface, allowing the anthocyanins inside to penetrate the highly absorbent gel layer with the solution, affecting the color development of the surface layer. Similar changes are observed when the amount of ethylene glycol used is reduced (Example 4). When low-melting-point polyester is not bonded to the surface layer (proportionality 1), the color change is rapid, but after being left for 5 minutes, the color becomes noticeably lighter. This is because the dissolution and leaching of anthocyanins are significant, and they penetrate the absorbent gel layer with the solution relatively quickly, resulting in a shorter color development time for the surface layer. Users may misjudge the results if they do not observe them immediately. If the material does not contain a hollow structure (proportional ratio 2), the amount of anthocyanin adsorbed decreases, resulting in a slower color change and affecting the adhesion strength of the anthocyanin, causing the color to fade after being left standing.

[0062] In Example 1, 1 mL of a pH 3 solution was dropped onto the urine pad prepared, and the color obtained after 10 seconds was recorded as the color data for the standard sample. Subsequently, color data was measured at 30 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, and 5 minutes using a colorimeter, and the color difference value △E was obtained by comparing it with the standard sample. Following the above method, the color difference values ​​△E were measured at 10 seconds, 30 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, and 5 minutes for proportionality 1 and proportionality 2. The results are shown in Figure 1. As can be seen from Figure 1, in Example 1, the color change with the passage of time is not clear (small and stable), whereas proportionality 1 develops color quickly, but the color change with the passage of time is rapid, the discoloration is unstable, and it is disadvantageous for the user to make an accurate judgment. Proportionality 2 develops color slowly, and the color change after standing was greater than in Example 1.

[0063] As will be readily apparent to those skilled in the art, the above are merely preferred embodiments of the present invention and do not limit it. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be within the scope of protection of the present invention.

Claims

1. A core-shell structure microsphere for indicating the pH of pet urine, characterized in that the shell layer is made of a low-melting-point polyester, the core layer is made of a porous water-absorbing material, and anthocyanins are adsorbed on the core layer.

2. The core-shell structure microsphere according to claim 1, characterized in that the melting point of the low-melting-point polyester is 80 to 120°C, and the porous water-absorbing material is a hollow microsphere of an acrylamide-acrylic acid copolymer.

3. A method for manufacturing a core-shell structure microsphere according to claim 1 or 2, characterized by comprising the following steps: S1: A step of dispersing a pore-forming agent in deionized water, then copolymerizing it with acrylamide, acrylic acid, and potassium persulfate to obtain a complex microsphere: S2: Step of removing the pore-forming agent from the composite microsphere to obtain hollow microspheres of the acrylamide-acrylic acid copolymer: S3: A step in which a portion of ethylene glycol is esterified with the hollow microspheres of the acrylamide-acrylic acid copolymer, and then terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol, and diethylene glycol are added to carry out an esterification reaction to obtain hollow microspheres whose surface is coated with a low-melting-point polyester: S4: A step of immersing hollow microspheres coated with a low-melting-point polyester in an aqueous solution containing anthocyanins to adsorb the material, then removing and drying them to obtain core-shell structure microspheres.

4. A method for producing a core-shell structure microsphere according to claim 3, characterized in that in step S1, the pore-forming agent is calcium carbonate with a particle size of 50 to 500 nm, and in step S2, the pore-forming agent is dissolved and removed with hydrochloric acid.

5. A method for producing core-shell structure microspheres according to claim 3, characterized in that in step S1, the molar ratio of acrylamide to acrylic acid is 1:(2-3), and the copolymerization reaction temperature is 60-80°C.

6. A method for producing core-shell structure microspheres according to claim 3, characterized in that in step S3, the catalyst used in the condensation reaction is antimony trioxide, the molar ratio of terephthalic acid, adipic acid, ethylene glycol, 2,3-pentanediol, and diethylene glycol is 1:(0.045-0.055):(1.2-1.3):(0.45-0.50):(0.10-0.12), and the molar ratio of ethylene glycol to acrylic acid is (10-30):

1.

7. A variable-color urine pad for pets, comprising, from top to bottom, a nonwoven fabric layer, a fast-absorbing layer, and a leak-proof layer, wherein the nonwoven fabric layer contains a core-shell structure microsphere described in claim 1 or 2, or a core-shell structure microsphere obtained by the manufacturing method described in any one of claims 3 to 6, and is characterized in that it produces a color change in accordance with the difference in acidity and baseness of the pet's urine.

8. A variable-color urine pad for pets according to claim 7, characterized in that the nonwoven fabric layer is a polypropylene nonwoven fabric containing the core-shell structure microspheres, the leak-proof layer is a PE film, and the fast-absorbing layer is an absorbent gel or absorbent resin.

9. A method for manufacturing a variable-color urine pad for pets according to claim 7 or 8, characterized by: obtaining a polypropylene composite nonwoven fabric by compound spinning a core-shell structure microsphere and polypropylene; sequentially laminating the polypropylene composite nonwoven fabric, a fast-absorbing layer and a leak-proof layer; fixing them with heat and pressure at 120 to 150°C; and further pressing the edges of the material with ultrasonic waves to obtain a variable-color urine pad for pets.

10. A pet diaper comprising a nonwoven fabric layer, a fast-absorbing layer, and a leak-proof layer, wherein the nonwoven fabric layer contains core-shell structure microspheres as described in claim 1 or 2, or core-shell structure microspheres obtained by the manufacturing method described in any one of claims 3 to 6, and is characterized in that it changes color according to the different acid-base concentrations of the pet's urine.

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