Variable color pet pad and method of making same

Abstract

The application belongs to the technical field of pet products, and particularly relates to a variable-color urine pad for pets and a preparation method thereof. From top to bottom, the variable-color urine pad comprises a non-woven fabric layer, a quick-absorbing layer and a leakage-proof layer in sequence. The non-woven fabric layer contains core-shell structure microspheres, the shell layer is low-melting-point polyester, the core layer is porous water-absorbing material, the core layer adsorbs anthocyanin, and the non-woven fabric layer and the quick-absorbing layer are bonded through hot pressing. The application can respond to different pH values of pet urine through color, and further determine the health condition of pets. Meanwhile, the low-melting-point polyester is used to improve the bonding strength, the structure setting of the hydrophobic shell layer and the hydrophilic core layer can prevent the loss of anthocyanin due to dissolution, and the color response stability is improved. Furthermore, the core-shell structure microspheres are arranged in the non-woven fabric layer, the color change can be observed from the surface layer in time, and the determination is prevented from being delayed due to the color change being blocked.

Description

Technical Field

[0001] This invention belongs to the field of pet product technology, specifically relating to a color-changing pet diaper pad and its preparation method. Background Technology

[0002] Cats are carnivores, and under normal dietary conditions and in a healthy state, they generally produce acidic urine with a pH value between 5.5 and 7.5, with an optimal range of around 6-6.5. Diet and disease are the main factors affecting the pH value of a cat's urine. Medications, stress, and strenuous exercise can also cause a shift in the pH of a cat's urine. Most domesticated cats primarily eat commercial cat food, and the vegetables and grains in this food can raise their urine pH. Eating dry food and drinking too little water can also lead to a more alkaline urine pH. A smaller percentage of cats are fed a raw food diet, consuming more meat, which can result in a more acidic urine pH.

[0003] In addition, many feline diseases are accompanied by a change in urine pH from the normal range to more acidic or more alkaline. For example, metabolic or respiratory acidosis, fever, gout, emphysema, urinary tract stones, kidney stones, diabetes, and leukemia can cause acidic urine pH; while metabolic or respiratory alkalosis, frequent vomiting, urinary retention, cystitis, urinary tract infections, renal tubular acidosis, and chronic glomerulonephritis can cause alkaline urine pH. When a cat's urine is acidic, calcium oxalate stones are more likely to form; when the urine is alkaline, ammonium phosphate crystals are more likely to precipitate, forming struvite stones. Stones can easily lead to inflammation of the urinary tract, bladder, and kidneys, and in severe cases, blockage of the urinary tract, causing hematuria and urinary retention, which can be life-threatening. Therefore, abnormal urine pH in cats can, to some extent, be an indicator of certain underlying diseases, especially urinary tract and kidney diseases. Therefore, by testing the pH level of a cat's urine, potential health problems can be detected early, and corresponding measures can be taken in a timely manner to keep the cat healthy.

[0004] To prevent cats' excrement from soiling the floor, pee pads are commonly used. Therefore, designing pee pads with a pH-indicating color-changing structure allows for timely observation of the cat's urine's acidity or alkalinity, thus aiding in assessing its health. Patent CN116762712A discloses a functional pet pee pad, comprising a non-woven fabric layer, a special ink printing area, a super absorbent polymer layer, and a waterproof and leak-proof layer, sequentially bonded from top to bottom. This design utilizes the principle of pH-based color change. The special ink printing area changes color when the urine, due to changes in the pet's pH level caused by illness, comes into contact with the special ink, thus enabling early detection of lesions caused by lower urinary tract diseases and providing guidance for timely treatment. However, the composition of the special ink is unknown. Although it is located between the non-woven fabric layer and the absorbent layer, the lack of additional treatment means that the super absorbent layer's high absorbency may cause the ink to seep into the absorbent layer with the urine, affecting the color's visibility on the surface.

[0005] Therefore, it is necessary to provide an improved color-changing pee pad for pets to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a color-changing diaper pad for pets and its preparation method. By using core-shell structured microspheres with anthocyanins adsorbed on them, the diaper pad can respond to different pH levels of pet urine with color, thereby judging the pet's health status. At the same time, the use of low-melting-point polyester improves the bonding strength, and its hydrophobicity can also prevent the dissolution and loss of anthocyanins, thereby improving the stability of the color response.

[0007] To achieve the above objectives, the first aspect of the present invention provides a core-shell structured microsphere for pet urine pH indication, wherein the shell layer is a low-melting-point polyester, the core layer is a porous water-absorbing material, and the core layer is adsorbed with anthocyanins.

[0008] Furthermore, the melting point of the low-melting-point polyester is 80–120°C; the porous absorbent material is acrylamide-acrylic acid copolymer hollow microspheres.

[0009] Secondly, the present invention also provides a method for preparing the core-shell structured microspheres described above, comprising the following steps:

[0010] S1. Disperse the pore-forming agent in deionized water, then add acrylamide, acrylic acid and potassium persulfate, and copolymerize to obtain composite microspheres;

[0011] S2. Remove the pore-forming agent from the composite microspheres to obtain acrylamide-acrylic acid copolymer hollow microspheres;

[0012] S3. Part of the ethylene glycol is esterified with the acrylamide-acrylic acid copolymer hollow microspheres, and then terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol and diethylene glycol are added to carry out esterification to obtain hollow microspheres with low melting point polyester coating on the surface.

[0013] S4. The hollow microspheres coated with low-melting-point polyester are immersed in an aqueous solution containing anthocyanins for adsorption, and then removed and dried to obtain core-shell structured microspheres.

[0014] Furthermore, in step S1, the porogen is calcium carbonate with a particle size of 50-500 nm; in step S2, the porogen is removed by dissolving in hydrochloric acid.

[0015] Furthermore, in step S1, the molar ratio of acrylamide to acrylic acid is 1:2 to 3; and the copolymerization reaction temperature is 60 to 80°C.

[0016] Furthermore, in step S3, the catalyst used in the esterification 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 and acrylic acid is 10~30:1.

[0017] Thirdly, the present invention provides a color-changing pee pad for pets, comprising, from top to bottom, a non-woven fabric layer, a quick-absorbing layer, and a leak-proof layer; wherein, the non-woven fabric layer contains the core-shell structured microspheres, or the core-shell structured microspheres obtained by the preparation method, for color response to different pH levels of pet urine, thereby determining the pet's health status.

[0018] Furthermore, the nonwoven fabric layer is a polypropylene nonwoven fabric containing the core-shell structured microspheres, the leak-proof layer is a PE film, and the quick-absorbing layer is a hydrogel or resin.

[0019] Fourthly, the present invention provides a method for preparing the above-mentioned color-changing diaper pad for pets, characterized in that core-shell structured microspheres and polypropylene are compositely spun to obtain polypropylene composite nonwoven fabric; the polypropylene composite nonwoven fabric, the quick-absorbing layer and the leak-proof layer are stacked in sequence, hot-pressed and fixed, and ultrasonically pressed at the edges of the materials to obtain the color-changing diaper pad for pets.

[0020] Furthermore, the temperature for hot pressing is 120–150°C.

[0021] Compared with the prior art, the technical solution of the present invention has the following main technical advantages:

[0022] The color-changing pee pad for pets provided by this invention uses a low-melting-point polyester shell and a porous absorbent material with anthocyanins adsorbed in the core layer. The internal layer is more hydrophilic than the external layer, which improves the adhesion of anthocyanins within the core, preventing dissolution and seepage under the influence of sweat and urine, thereby improving the stability of the color response and preventing color changes over time from affecting judgment. It also enhances the adsorption of urine, allowing for timely contact and color development with the anthocyanins. The hollow structure further increases the amount of anthocyanins adsorbed, thus improving the sensitivity of the color response. The external low-melting-point polyester is a hydrophobic material, which improves compatibility with non-woven fabrics and allows for hot-pressing and melting, improving adhesion. This invention can respond to different pH levels in pet urine with color, thereby assessing the pet's health. Furthermore, by incorporating core-shell structured microspheres within the non-woven fabric layer, color changes can be observed promptly from the surface, preventing color changes from being obstructed and delaying judgment. Attached Figure Description

[0023] Figure 1 The curves showing the change of color difference values ​​over test time are for Example 1 and Comparative Examples 1 and 2. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] This invention provides a core-shell structured microsphere for pet urine pH indication, wherein the shell layer is a low-melting-point polyester, the core layer is a porous absorbent material, and anthocyanins are adsorbed on the core layer. The low-melting-point polyester has a melting point of 80-120℃; the porous absorbent material is an acrylamide-acrylic acid copolymer hollow microsphere.

[0026] This design, with greater hydrophilicity inside than outside, enhances the fixation strength of anthocyanins within, preventing dissolution and seepage in sweat and urine, and also improves the adsorption of urine, thus facilitating timely contact with anthocyanins for color development. The hollow structure further increases the adsorption of anthocyanins, thereby improving color response sensitivity. The outer low-melting-point polyester is a hydrophobic material, which improves compatibility with nonwoven fabrics and allows for hot-pressing and melting, enhancing adhesion.

[0027] This invention also provides a method for preparing the core-shell structured microspheres described above, comprising the following steps:

[0028] S1. Disperse the pore-forming agent in deionized water, then add acrylamide, acrylic acid and potassium persulfate, and copolymerize to obtain composite microspheres;

[0029] S2. Remove the pore-forming agent from the composite microspheres to obtain acrylamide-acrylic acid copolymer hollow microspheres;

[0030] S3. Esterify 1 / 2 to 1 / 5 of the total amount of ethylene glycol with the acrylamide-acrylic acid copolymer hollow microspheres, and then add terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol and diethylene glycol to carry out esterification reaction to obtain hollow microspheres with low melting point polyester coating on the surface.

[0031] S4. The hollow microspheres coated with low-melting-point polyester are immersed in an aqueous solution containing anthocyanins for adsorption, and then removed and dried to obtain core-shell structured microspheres.

[0032] This invention constructs a hollow structure through a pore-forming agent, and forms a hydrophilic layer through copolymerization of acrylamide and acrylic acid, providing a basis for anthocyanin adsorption and providing carboxyl active groups for grafting low-melting-point polyester. Ethylene glycol is esterified before the carboxyl group of acrylic acid to form ethylene glycol acrylate, and then other monomers are added. The branched monomers help to form low-melting-point polyester, providing a basis for hot-press bonding.

[0033] In step S1, the porogen is calcium carbonate with a particle size of 50-500 nm, preferably 50-200 nm; in step S2, the porogen is removed by dissolving in hydrochloric acid.

[0034] In step S1, the molar ratio of acrylamide to acrylic acid is 1:2-3; the copolymerization reaction temperature is 60-80℃. By controlling the content of acrylamide and acrylic acid, the hydrophilicity and the content of the low-melting-point polyester grafted onto the surface can be adjusted. When the acrylic acid content is too low, the coating effect of the low-melting-point polyester is reduced, causing anthocyanins to easily dissolve and be lost, and even penetrate into the more absorbent quick-absorbing layer, thus affecting the color development effect. When the acrylic acid content is too high, it will reduce the hydrophilicity, affect the anthocyanin loading, and thus affect the color development sensitivity.

[0035] In step S3, the catalyst used in the esterification 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 the total amount of ethylene glycol to acrylic acid is 10~30:1.

[0036] This invention provides a color-changing pee pad for pets, comprising, from top to bottom, a non-woven fabric layer, a quick-absorbing layer, and a leak-proof layer; wherein, the non-woven fabric layer contains the core-shell structured microspheres, or the core-shell structured microspheres obtained by the preparation method, for color response to different pH levels of pet urine, thereby determining the pet's health status.

[0037] Furthermore, the nonwoven fabric layer is a polypropylene nonwoven fabric containing the core-shell structured microspheres, and the amount of core-shell structured microspheres is 5% to 15% of the mass of polypropylene; the leak-proof layer is a PE film; and the quick-absorbing layer is a hydrogel or resin.

[0038] Fourthly, the present invention provides a method for preparing the above-described pet color-changing diaper pad, characterized in that core-shell structured microspheres and polypropylene are compositely spun to obtain a polypropylene composite nonwoven fabric; the polypropylene composite nonwoven fabric, a quick-absorbing layer, and a leak-proof layer are sequentially stacked, hot-pressed for fixation, and ultrasonically pressed at the edges of the materials to obtain the pet color-changing diaper pad. Further, the hot-pressing temperature is 120-150℃.

[0039] Example 1

[0040] A color-changing pee pad for pets, comprising, from top to bottom, a non-woven fabric layer containing core-shell structured microspheres of polypropylene non-woven fabric, a quick-absorbing layer containing absorbent gel, and a leak-proof layer containing a PE film; the preparation method is as follows:

[0041] Core-shell structured microspheres and polypropylene were compositely spun to obtain polypropylene composite nonwoven fabric (the amount of core-shell structured microspheres was 8% of the mass of polypropylene); PE film, hydrogel and polypropylene composite nonwoven fabric were stacked in sequence, then hot-pressed at 130℃ and ultrasonically pressed at the edges of the materials to obtain color-changing diaper pads for pets.

[0042] The preparation method of the core-shell structured microspheres is as follows:

[0043] S1. 150 nm of calcium carbonate is dispersed in deionized water (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 centrifuged and dried to obtain composite microspheres.

[0044] S2. Hydrochloric acid was used to remove calcium carbonate from the composite microspheres to obtain acrylamide-acrylic acid copolymer hollow microspheres;

[0045] S3. One-quarter of the total amount of ethylene glycol is esterified with 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 for esterification to obtain hollow microspheres with low melting point polyester coating. 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; the molar ratio of the total amount of ethylene glycol to acrylic acid is 15:1.

[0046] S4. The hollow microspheres coated with low-melting-point polyester are immersed in an aqueous solution containing anthocyanins (red cabbage extract, commercially available) (anthocyanin mass fraction is 0.5%, and the mass of the hollow microspheres is 10 times the mass of the anthocyanins) for adsorption, and then removed and dried to obtain core-shell structured microspheres.

[0047] Example 2

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

[0049] Example 3

[0050] The difference from Example 1 is that the molar ratio of acrylamide to acrylic acid is 1:3.

[0051] Example 4

[0052] The difference from Example 1 is that the total amount of ethylene glycol and the molar ratio of acrylic acid is 5:1.

[0053] Example 5

[0054] The difference from Example 1 is that the total amount of ethylene glycol and the molar ratio of acrylic acid is 30:1.

[0055] Comparative Example 1

[0056] The difference from Example 1 is that the preparation method of the core-shell structured microspheres is as follows:

[0057] S1. 150 nm of calcium carbonate is dispersed in deionized water (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 centrifuged and dried to obtain composite microspheres.

[0058] S2. Hydrochloric acid was used to remove calcium carbonate from the composite microspheres to obtain acrylamide-acrylic acid copolymer hollow microspheres;

[0059] S3. The acrylamide-acrylic acid copolymer hollow microspheres are immersed and adsorbed in an aqueous solution containing anthocyanins (red cabbage extract, commercially available) (anthocyanin mass fraction is 0.5%, and the mass of hollow microspheres is 10 times the mass of anthocyanins), and then removed and dried to obtain microspheres.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that calcium carbonate was not added during the preparation of the core-shell structured microspheres.

[0062] Cat urine samples were collected and buffer solutions were added to prepare solutions with pH values ​​of 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12. The urine pads prepared in Example 1 were used as samples, and 1 mL of each solution with a different pH value was added. The color development time and color change were observed, and the results are shown in Table 1. Then, 1 mL of a solution with a pH value of 3 was added to the urine pads prepared in Examples 1-5 and Comparative Examples 1-2, and the color development time, color change, and color change after 5 minutes were observed, and the results are shown in Table 2.

[0063] Table 1. Test results of Example 1 in solutions with different pH values

[0064]

[0065] As can be seen from Table 1, the urine pad prepared by this invention can produce color changes at different pH values. Based on this, a colorimetric card can be made, which can facilitate users to compare the color in a timely manner, thereby enabling visual observation of the acidity and alkalinity of cat urine.

[0066] Table 2 Test Results of Examples and Comparative Examples

[0067]

[0068] As shown in Table 2, reducing the amount of acrylic acid has little effect on the initial color change. However, after a certain period of time, the color becomes lighter and unevenly distributed. This may be because the reduced acrylic acid content leads to a decrease in the content of low-melting-point polyester grafted onto the surface layer, causing the anthocyanins inside to penetrate into the more absorbent hydrogel layer with the solution, thus affecting the appearance of the surface color. A similar change occurs when the amount of ethylene glycol is reduced. When the surface layer is not grafted with low-melting-point polyester, although the color changes quickly, it becomes significantly lighter after 5 minutes, indicating severe anthocyanin dissolution and loss, which rapidly penetrates into the hydrogel layer with the solution, resulting in a shorter surface color appearance time. If the user does not observe it in time, it is easy to make a misjudgment. When there is no hollow structure, the color change is slow due to the reduced anthocyanin adsorption, and the binding strength of the anthocyanins is also affected, resulting in a lighter color after standing.

[0069] 1 mL of a pH 3 solution was added to the urinal pad prepared in Example 1. The color obtained after 10 seconds was recorded as the standard sample color data. Then, the color data at 30 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, and 5 minutes were measured using a colorimeter to obtain the color difference value ΔE compared to the standard sample. The color difference values ​​ΔE of Comparative Examples 1 and 2 at 10 seconds, 30 seconds, 1 minute, 2 minutes, 3 minutes, 4 minutes, and 5 minutes were then measured using the same method. Figure 1As shown, the color of Example 1 did not change significantly with increasing placement time, while Comparative Example 1, although developing color quickly, showed rapid color change with increasing placement time, indicating unstable color change, which is not conducive to users making correct judgments. Comparative Example 2 developed color more slowly, and the color change was greater than that of Example 1 after placement.

[0070] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A color-changing pee pad for pets, characterized in that, From top to bottom, it includes a non-woven fabric layer, a quick-absorbing layer, and a leak-proof layer; wherein, the non-woven fabric layer contains core-shell structured microspheres, which are used to respond to different pH levels in pet urine with color, thereby determining the pet's health status; the preparation method of the core-shell structured microspheres includes the following steps: S1. Disperse the porogen in deionized water, then add acrylamide, acrylic acid and potassium persulfate, and copolymerize to obtain composite microspheres; the molar ratio of acrylamide and acrylic acid is 1:2-3; S2. Remove the pore-forming agent from the composite microspheres to obtain acrylamide-acrylic acid copolymer hollow microspheres; S3. One-quarter of the total amount of ethylene glycol is subjected to an esterification reaction with the acrylamide-acrylic acid copolymer hollow microspheres. Then, terephthalic acid, adipic acid, the remaining ethylene glycol, 2,3-pentanediol, and diethylene glycol are added for another esterification reaction to obtain hollow microspheres coated with low-melting-point polyester. 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 ethylene glycol to acrylic acid is 10~30:

1. The melting point of the low-melting-point polyester is 80~120℃. S4. The hollow microspheres with low melting point polyester coating are immersed in an aqueous solution containing anthocyanins for adsorption, and then removed and dried to obtain core-shell structured microspheres. The method for preparing the pet color-changing diaper pad includes: spinning core-shell structured microspheres and polypropylene to obtain a polypropylene composite nonwoven fabric; stacking the polypropylene composite nonwoven fabric, the quick-absorbing layer and the leak-proof layer in sequence, hot-pressing them at 120-150℃, and ultrasonically pressing the edges of the materials to obtain the pet color-changing diaper pad.

2. The pet color-changing pee pad according to claim 1, characterized in that, In step S1, the porogen is calcium carbonate with a particle size of 50-500 nm; in step S2, the porogen is removed by dissolving in hydrochloric acid.

3. The pet color-changing pee pad according to claim 1, characterized in that, In step S1, the copolymerization reaction temperature is 60–80°C.

4. The pet color-changing pee pad according to claim 1, characterized in that, In step S3, the catalyst used in the esterification reaction is antimony trioxide.

5. The pet color-changing pee pad according to claim 1, characterized in that, The nonwoven fabric layer is a polypropylene nonwoven fabric containing the core-shell structured microspheres; the leak-proof layer is a PE film; and the quick-absorbing layer is a hydrogel or resin.

6. A pet diaper, characterized in that, It includes a nonwoven fabric layer, a quick-absorbing layer, and a leak-proof layer; wherein, the nonwoven fabric layer contains core-shell structured microspheres as described in any one of claims 1 to 5 for use in pet color-changing urine pads, which are used to respond to different pH levels of pet urine with color, thereby determining the pet's health status.

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