Biodegradable particles as well as preparation method and application thereof

Abstract

The invention relates to the field of macromolecules, in particular to biodegradable particles as well as a preparation method and application thereof. The biodegradable particles contain polyglycolic acid resin, a crystallization promoter and an optional auxiliary agent, and the polyglycolic acid resin is at least one of homopolymerized polyglycolic acid and copolymerized polyglycolic acid; the crystallization accelerant is selected from high-temperature plastic, and the melting temperature of the high-temperature plastic is higher than that of the polyglycolic acid resin by 20 DEG C or above. The biodegradable powder is prepared from the polyglycolic acid resin, the crystallization accelerant and the optional auxiliary agent, the powder is extruded and granulated to prepare particles, and the particles have good water absorption and degradability, can be used for composting and preparing a soil conditioner after being used, are suitable for being used as an excrement treatment material, and have good application prospects. The pet excrement can be conveniently subjected to garbage treatment, the pet excrement can be fully turned into wealth, and the pet excrement recycling device has high application value.

Description

Technical Field

[0001] This invention relates to the field of polymers, and more specifically, to a biodegradable particle, its preparation method, and its uses. Background Technology

[0002] Excrement handling materials, such as cat litter, are typically granular and used to cover the feces and urine of cats and other pets. They provide a covering effect, encapsulating the pet's waste for easy removal or further processing. Currently available cat litter is divided into organic and inorganic types. Organic cat litter includes wood shavings, paper scraps, bamboo litter, grass litter, grain litter, and cereal litter, while inorganic cat litter includes bentonite litter, crystal (silica gel) litter, and zeolite litter.

[0003] Cat litter sorting depends on its material. When using cat litter, its environmental impact should be considered, and it should be disposed of correctly according to the corresponding waste sorting guidelines. Below are waste sorting guidelines for different types of cat litter:

[0004] Bentonite litter: Primarily made of bentonite, it is a non-biodegradable type of sand and should be classified as dry waste. Pine litter: Mainly composed of wood powder and binder, it dissolves in water, therefore it also belongs to dry waste. Tofu litter: Primarily made from tofu residue, it dissolves in water, therefore it belongs to wet waste. Corn litter: Primarily made from corn, it also belongs to wet waste. Crystal litter (silica gel litter): Primarily made of silica, although environmentally friendly, it is non-biodegradable, therefore it also belongs to dry waste.

[0005] It's important to note that if cat litter is contaminated with animal feces, it cannot be recycled or reused and is currently classified as other waste. The disposal methods for other waste vary depending on its material, primarily including landfill, incineration, and composting. Because cat litter comes in many different types, its subsequent classification and processing is correspondingly complex. Therefore, a new need has emerged that allows for convenient disposal of pet waste while also effectively turning it into a valuable resource.

[0006] Flushing used cat litter along with pet excrement into the toilet is one way to solve waste sorting. However, its feasibility depends on whether the material of the cat litter will cause blockages in the sewer. CN 115462320 A discloses a flushable bentonite cat litter with rapid dispersion and dissolution in water. The litter composition requires 40-48 parts of bentonite. Although 5-8 parts of effervescent tablets are added, which can use the bubbles generated by water to dissolve the bentonite and other components, bentonite does not dissolve in water and expands to 20-30 times its original volume when wet, making it easy to accumulate in the sewer system. Therefore, the amount of cat litter used cannot be too much, and there are relatively high requirements for flushing flow rate and flushing speed.

[0007] CN115380833A discloses a whole-grain expanded granular cat litter. Using corn starch as raw material, through enzymatic hydrolysis, oxidation, chitosan grafting, and octenyl succinic anhydride cross-linking, a cat litter additive with excellent water absorption, deodorization, and clumping properties was obtained. Further, using this porous modified corn starch, along with soybean meal, wheat bran, wood ash, plant antibacterial and deodorizing agents, and guar gum as raw materials, a whole-grain expanded granular cat litter was produced, exhibiting extremely strong water absorption, clumping, and deodorizing properties. However, this whole-grain expanded granular cat litter uses whole grains as its raw material, resulting in higher costs. Whole grains also have many other uses, such as in animal feed production. Furthermore, its process is relatively complex, requiring chemical modification of the raw materials through grafting and cross-linking.

[0008] Therefore, a new type of material suitable for excrement treatment can be obtained by adopting a simpler preparation process, which can save biological resources, facilitate the disposal of pet excrement, and fully turn pet excrement into a valuable resource, thus creating a new demand. Summary of the Invention

[0009] To address the aforementioned problems in the prior art, this invention provides a biodegradable granule. Specifically, it provides a biodegradable granular excrement treatment material, its preparation method, and its application as an excrement treatment material. This invention uses polyglycolic acid resin as the matrix of the biodegradable granules. The polyglycolic acid resin, crystallization accelerator, and optional additives are used to prepare a biodegradable powder, which is then extruded and granulated into granules. These granules possess water absorption and biodegradability, and can be composted and used to make soil conditioners after use. Suitable as an excrement treatment material, it conveniently treats pet excrement as waste and effectively transforms pet excrement into a valuable resource, demonstrating high application value.

[0010] The biodegradable granules provided by this invention have two post-use treatment methods. First, they can be flushed directly into the toilet, eliminating the need for waste sorting. Second, they can be collected, further processed, and used as a soil conditioner to adjust the pH of saline-alkali soils and increase soil fertility. Through optimization of the preferred scheme of this invention, biodegradable granules that can be directly flushed with water and do not adhere to the walls of the container can be obtained. Furthermore, through further optimization, this invention can also produce biodegradable granules with only slight or no powder shedding, making them easy to clean. Specifically:

[0011] A first aspect of the present invention is to provide biodegradable particles comprising a polyglycolic acid resin, a crystallization accelerator, and optional additives, wherein the polyglycolic acid resin is at least one of homopolymer polyglycolic acid and copolymer polyglycolic acid; and the crystallization accelerator is selected from high-temperature plastics, wherein the melting temperature of the high-temperature plastic is at least 20°C higher than the melting temperature of the polyglycolic acid resin.

[0012] According to the present invention, the polyglycolic acid resin can be at least one of homopolymer polyglycolic acid and copolymer polyglycolic acid; wherein, the copolymer polyglycolic acid is a copolymer polyglycolic acid obtained by polymerization of glycolic acid and comonomer. For example, preferably, the structural units derived from glycolic acid monomers account for more than 80 mol% of the total number of structural units in the copolymer polyglycolic acid, more preferably more than 90 mol%, based on a total of 100 mol% of all structural units. The range of selectable comonomers is wide, and for example, it can be at least one of cyclic monomers, lactones, carbonates, ethers, ether esters, amides, hydroxycarboxylic acids, alkyl esters of hydroxy acids, aliphatic diols, aliphatic dicarboxylic acids, and esters formed by aliphatic diols and aliphatic dicarboxylic acids. For example, the cyclic monomer is at least one of 1,4-dioxane-2,3-dione and lactide; and / or, the lactone is at least one of p-propiolactone, p-butyrolactone, p-neopentrolactone, p-butyrolactone, δ-pentanolactone, p-ethylδ-pentanolactone, and ε-caprolactone; and / or, the carbonate is trimethylene carbonate; and / or, the ether is 1,3-dioxane; and / or, the ether ester is dioxane; and / or, the amide is preferably ε-caprolactam; and / or, the hydroxycarboxylic acid is at least one of lactic acid, 3-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, and 6-hydroxyhexanoic acid; and / or, the aliphatic diol is ethylene glycol and / or 1,4-butanediol; and / or, the aliphatic dicarboxylic acid is succinic acid and / or adipic acid.

[0013] According to some preferred embodiments of the present invention, the polyglycolic acid resin is a homopolymer polyglycolic acid. The present invention does not have particular requirements regarding the molecular weight of the homopolymer polyglycolic acid.

[0014] According to some preferred embodiments of the present invention, the melting temperature of the high-temperature plastic is higher than 250°C, and more preferably selected from at least one of PEEK (polyether ether ketone), PPS (polyphenylene sulfide), PA46 (nylon 46), and PA10T (nylon 10T).

[0015] According to some preferred embodiments of the present invention, the crystallization promoter is derived from powdered high-temperature plastic raw materials. Preferably, the high-temperature plastic raw materials are powders of 200 mesh or higher, for example, they can be collected through a sieve of 200 mesh or higher.

[0016] According to some preferred embodiments of the present invention, the content of the crystallization accelerator is 0.1-1 parts by weight, preferably 0.5-0.8 parts, relative to 100 parts of polyglycolic acid resin.

[0017] According to some preferred embodiments of the present invention, the biodegradable particles are at least one of columnar and spherical shapes, preferably cylindrical.

[0018] More preferably, when the biodegradable particles are cylindrical, the length of the biodegradable particles is 2-20 mm, preferably 2-10 mm; and the diameter is 2-10 mm, preferably 2-5 mm.

[0019] According to some preferred embodiments of the present invention, the additives are divided into melt processing aids and granulation aids. The melt processing aids may or may not be added, and the granulation aids may or may not be added. The biodegradable granules are prepared by the following method:

[0020] Raw materials including polyglycolic acid resin, crystallization promoter and optional melt processing aid are blended, melt granulated at the melting temperature of the polyglycolic acid resin, and then crushed and sieved to obtain biodegradable powder.

[0021] The biodegradable powder is then mixed with an optional granulation aid, and granulated by powder extrusion, with optional coating added to obtain the biodegradable granules.

[0022] For powder extrusion granulation, well-known powder extrusion granulation methods (including dry and wet methods) can be used to manufacture powder into granules by extrusion, for example, in a granulator.

[0023] According to some preferred embodiments of the present invention, the particle size range of the biodegradable powder is 60-90 mesh, preferably 60-80 mesh. Biodegradable particles prepared from biodegradable powder within this preferred particle size range are easy to form and do not easily shed powder.

[0024] According to some preferred embodiments of the present invention, the melt processing aid includes an antioxidant, which is of an industry-standard type and dosage. Preferably, the antioxidant is selected from at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 2246, antioxidant CA, and antioxidant 626, and more preferably from at least one of antioxidant 168 and antioxidant 1010. The dosage of the antioxidant is a conventional dosage in the plastics industry; for example, based on parts by weight, relative to 100 parts of polyglycolic acid resin, the dosage of the antioxidant is 0.1-1 parts, preferably 0.2-0.6 parts, and for example, the most conventional 0.5 parts.

[0025] According to some preferred embodiments of the present invention, the granulation aid includes one or more of binders, deodorants, fragrances, and disintegrants.

[0026] According to some preferred embodiments of the present invention, the binder is selected from at least one of starch (e.g., corn starch, tapioca starch), polyvinyl alcohol, polyethylene oxide, polyethylene glycol, alginate, sodium alginate, guar gum, konjac flour, xanthan gum, pullulan, gelatin, polyvinylpyrrolidone, sodium polyacrylate, carbomer, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose. Thus, the resulting biodegradable particles are less prone to powdering during shaking and collision.

[0027] According to some preferred embodiments of the present invention, the deodorizing agent is selected from at least one of activated carbon, extraction residue of roasted coffee beans, tea residue, wood flour, rice husk powder, peanut shell powder, and coffee grounds powder.

[0028] According to some preferred embodiments of the present invention, the fragrance agent is selected from peppermint flavoring, lemon flavoring, anethole, ambroxol, violetin, isobutylquinoline, undecylaldehyde, undecenal, eugenol, octylaldehyde, orange, galacin, carrageenan, citrulline, camphor, coumarin, anise oil, geraniol, geraniol, styrax acetate, cedrol acetate, terpineol acetate, benzyl acetate, linalool acetate, amyl salicylate, white Lehman sandalwood, cis-jasmone, citral, citronellol, citronellol, eucalyptol, methyl dihydrojasmone, dihydromyrcenol. At least one of the following: diphenyl oxide, cinnamyl alcohol, cedarwood, geranium, terpineol, dynasty ketone, damascone, damasne, thymol, basil, patchouli, vanillin, cyclopentadenin lactone, fructose ester, florpy, hexylcinnamaldehyde, peppermint, neojasmine aldehyde, bergamot, ethyl cyclohexylpropionate, maltol, citrus, muscone, methyl ionone, methyl nonyl acetaldehyde, methyl phenyl acetate, ethyl methyl phenyl glycidyl acid, menthol, eucalyptol, lauryl aldehyde, ethyl butyrate, raspberry ketone, limonene, neolimonene aldehyde, limonene aldehyde, rose ether, and rosemary. Solid fragrances are preferably crushed into powder and then added to the base resin; liquid fragrances can be added directly to the base resin.

[0029] According to some preferred embodiments of the present invention, the disintegrant is selected from water-absorbing and swelling disintegrants and / or gas-producing disintegrants, preferably at least one of sodium bicarbonate and sodium carbonate. Preferably, when adding the disintegrant, a direct compression process of effervescent tablets is used to prepare biodegradable granules.

[0030] According to some preferred embodiments of the present invention, the amount of the binder is 0-60 parts by weight, preferably 5-40 parts, and more preferably 5-20 parts, relative to 100 parts of biodegradable powder. Under this preferred range of dosage, the resulting biodegradable particles are less prone to powder loss, and the particles are less likely to stick to the wall after adding water, making them easier to handle.

[0031] And / or, the amount of the deodorant used is 0-30 parts, preferably 5-20 parts.

[0032] And / or, the amount of the flavoring agent is 0-0.05 parts, preferably 0.03-0.05 parts;

[0033] And / or, the amount of the disintegrant is 0-10 parts, preferably 2-5 parts.

[0034] If a wet method is used to wet the material by spraying water before granulation, the granules must be dried after granulation. The drying temperature and time can be set according to the standard operating procedure (select the drying temperature and time according to the environment, for example, 80℃, 4h).

[0035] According to some more preferred embodiments of the present invention, the content of the crystallization accelerator is preferably 0.5-0.8 parts by weight relative to 100 parts of polyglycolic acid resin; the particle size range of the biodegradable powder is 60-90 mesh, preferably 60-80 mesh; the amount of the binder is 0-60 parts by weight relative to 100 parts of biodegradable powder, preferably 5-20 parts; and the amount of the disintegrant is 0-10 parts, preferably 2-5 parts. When the amount of binder is 0, a coating is preferably added. In a more preferred embodiment, the biodegradable particles (excrement treatment material) provided by the present invention have good disintegration properties when exposed to large amounts of water, and can encapsulate excrement and flush it into the sewer without clogging the sewer system. The excrement treatment material that can be flushed into the sewer system provided by the present invention is convenient to use, avoiding the trouble of sorting and disposing of used excrement treatment materials (such as cat litter) in the prior art, and saving land and energy required for processing dry waste.

[0036] A second aspect of the present invention is to provide a method for preparing the biodegradable particles described in the first aspect, comprising:

[0037] Raw materials including polyglycolic acid resin, crystallization promoter and optional melt processing aid are blended, melt granulated at the melting temperature of the polyglycolic acid resin, and then crushed and sieved to obtain biodegradable powder.

[0038] The biodegradable powder is then mixed with an optional granulation aid, and granulated by powder extrusion, with optional coating added to obtain the biodegradable granules.

[0039] According to some preferred embodiments of the present invention, the polyglycolic acid resin raw material is a polyglycolic acid resin raw material and / or obtained by crushing recycled polyglycolic acid products. As mentioned above, the polyglycolic acid resin is at least one of homopolymer polyglycolic acid and copolymer polyglycolic acid, preferably homopolymer polyglycolic acid.

[0040] According to some preferred embodiments of the present invention, the blending is carried out in a high-speed pulverizer.

[0041] According to some preferred embodiments of the present invention, the melt granulation conditions include a temperature of 200-230°C.

[0042] The biodegradable powder has a particle size range of 60-90 mesh, preferably 60-80 mesh.

[0043] In the above preparation method, the crystallization promoter is a powdered high-temperature plastic raw material. Preferably, the high-temperature plastic raw material is a powder of 200 mesh or higher.

[0044] In the above preparation method, preferably, the content of the crystallization accelerator is 0.1-1 parts by weight, more preferably 0.5-0.8 parts, relative to 100 parts of polyglycolic acid resin.

[0045] As mentioned above, the crystallization promoter is selected from high-temperature plastics, and the melting temperature of the high-temperature plastic is more than 20°C higher than the melting temperature of the polyglycolic acid resin, preferably the melting temperature of the high-temperature plastic is higher than 250°C; more preferably the high-temperature plastic is selected from at least one of PEEK, PPS, PA46, and PA10T.

[0046] According to some preferred embodiments of the present invention, the powder extrusion granulation method is dry powder extrusion granulation or wet powder extrusion granulation. Known dry powder extrusion granulation or wet powder extrusion granulation methods can be used to manufacture powder into granules by extrusion, for example, in a granulator, including but not limited to using the tablet granulation machine of the present invention for powder extrusion granulation.

[0047] Preferably, the above-mentioned particles are coated. Well-known coating processes and equipment (such as coating machines, fluidized bed coating, rotary coating, etc.) are used. The coating step includes coating the particles obtained by powder extrusion granulation with a coating solution, followed by drying to remove the solvent from the coating solution.

[0048] More preferably, the coating solution comprises a film-forming material and a solvent; even more preferably,

[0049] The film-forming material includes at least one of starch, HPMC cellulose (hydroxypropyl methylcellulose), polyethylene glycol, and PVP (polyvinylpyrrolidone), and / or the solvent is selected from water and / or ethanol, and / or the concentration of the film-forming material in the coating solution is 1-10 wt%.

[0050] The shape of the biodegradable granules (excrement treatment material) of the present invention can be any shape of existing known excrement treatment materials, such as cylindrical, spherical, etc. Furthermore, the size is not particularly limited; for example, if cylindrical, the length is 2-20 mm, preferably 2-10 mm, and the diameter is 2-10 mm, preferably 2-5 mm.

[0051] The selection and dosage of raw materials such as melt processing aids and granulation aids are as described in the first aspect, and will not be repeated here.

[0052] A third aspect of the present invention is to provide the use of the biodegradable particles described in the first aspect or the second aspect as a material for treating animal excrement.

[0053] A fourth aspect of the present invention is to provide a soil conditioner comprising the biodegradable particles described in the first aspect or the biodegradable particles obtained by the preparation method described in the second aspect, animal excrement, and optionally a soil adjuvant; preferably, the animal excrement is encapsulated in the biodegradable particles.

[0054] A fifth aspect of the present invention is to provide a method for preparing the soil conditioner described in the fourth aspect, comprising subjecting a material including biodegradable particles and animal excrement to high-temperature sterilization and composting treatment to remove pathogens and insect eggs from the excrement, and then optionally adding a soil adjuvant to obtain the soil conditioner; preferably, the soil adjuvant includes at least one of calcium carbonate, wood ash, and chemical fertilizer.

[0055] Compared with the prior art, the present invention has the following advantages:

[0056] The biodegradable granules of this invention have good water absorption and are easily degraded in water. They can conveniently dispose of pet excrement and can also be further processed into soil conditioners. Furthermore, they do not rely on grains or other raw materials, thus avoiding the consumption of grain raw materials. The preparation process is simple, making it a new type of excrement treatment material suitable for widespread application.

[0057] The biodegradable granules (excrement treatment material) provided by this invention, after being used by pets, contain pet excrement and, after high-temperature composting, possess fertility. Furthermore, the PGA degradation products are acidic, which has the function of regulating pH value, thereby adjusting the acidity and fertility of saline-alkali land. This invention also provides a method to improve the utilization rate of biodegradable materials and pet excrement in the economic cycle.

[0058] The biodegradable granules provided by this invention can be made from used PGA disposable products. After washing, crushing and screening, they can be used as PGA raw materials to remanufacture the biodegradable granules of this invention, thereby improving the utilization rate of waste PGA products in the economic cycle. Detailed Implementation

[0059] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0060] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] The preparation method of the powder used for biodegradable particles in the specific embodiment is as follows: biodegradable materials such as PGA and PLA (which can be commercially available granules or recycled disposable PGA products) are processed or modified, then crushed in a pulverizer, and then sieved using a sieve. The powder is classified and collected according to its mesh size (range 60-100 mesh).

[0062] The PGA raw material (i.e., polyglycolic acid) was purchased from Pujing and is a homopolymer PGA, extrusion grade; the PGA tableware was made by processing and molding the PGA raw material in the laboratory.

[0063] PEEK (polyether ether ketone) manufacturer: Jilin Zhongyan Polymer Materials Co., Ltd.;

[0064] PPS (polyphenylene sulfide), manufacturer: NHU 1190C;

[0065] PA46 (i.e., poly(4-aminobenzoamide-6-hydroxyhexanoic acid)), manufacturer: DSM;

[0066] PVA powder that is water-soluble at room temperature; Manufacturer: Sichuan Weihua Chemical Co., Ltd.

[0067] PLA (polylactic acid), manufacturer: Hisun Biotech REVODE190.

[0068] PA10T (i.e., Nylon 10T), manufacturer: Kingfa Science & Technology;

[0069] In the embodiments of the present invention, the raw materials PEEK, PPS, PA46, and PA10T were all crushed, ground, and sieved, and the powder obtained from 200 mesh or larger was used in the embodiments.

[0070] In the following examples and comparative examples, the extrusion granulation is dry powder extrusion granulation, which is carried out at room temperature in a tablet granulation machine; the machine manufacturer is: Nanjing Sanpu Granulation; model SET-100NH.

[0071] Example 1:

[0072] PGA raw materials, PEEK, and antioxidants (antioxidant 168: antioxidant 1010 in a mass ratio of 1:1) are blended in a mass ratio of 100:0.5:0.5. The mixture is then melt-granulated at 200-220℃, dried, and pulverized and sieved in a high-speed pulverizer. 90-mesh powder is selected, and the powder is kept dry. It is then put into a pelletizing machine for extrusion granulation to produce biodegradable granules. The biodegradable granules are cylindrical with a diameter of 6 mm and a height of 4 mm.

[0073] Example 2:

[0074] Used disposable PGA tableware was washed to remove oil stains, dried, and then crushed into fragments to obtain PGA raw material. PGA, PPS, and antioxidant (same as in Example 1) were blended in a mass ratio of 100:0.8:0.5, melt-granulated at 200-220°C, dried, and then pulverized and sieved using a high-speed pulverizer with a 90-mesh screen to obtain biodegradable powder. Commercially available starch was added to the biodegradable powder, and the mixture was mixed evenly at a mass ratio of 4:1. The mixture was dried with hot air and then extruded into biodegradable granules using a granulator. The biodegradable granules were cylindrical with a diameter of 6 mm and a height of 4 mm.

[0075] Example 3:

[0076] PGA raw material, PA46, and antioxidant (antioxidant 168: antioxidant 1010 in a mass ratio of 1:1) are blended in a mass ratio of 100:0.5:0.5, melt-granulated at 200-220℃, then dried, and then pulverized and sieved in a high-speed pulverizer with a 90-mesh screen to obtain biodegradable powder.

[0077] Add 60-mesh, room-temperature water-soluble PVA powder (commercially available) to biodegradable powder. Mix the biodegradable powder and PVA powder in a mass ratio of 5:2. Remove moisture with hot air, keep dry, and place in a pelletizing machine for extrusion granulation to produce biodegradable granules. The biodegradable granules are cylindrical with a diameter of 6 mm and a height of 4 mm.

[0078] Example 4:

[0079] The biodegradable granules prepared in Example 1 were spread on a coating machine and sprayed with a guar gum (1%) aqueous solution. Then they were immediately placed in an oven to dry.

[0080] Example 5:

[0081] Following the method in Example 1, PGA raw materials, PA10T (manufacturer: Kingfa Science & Technology), and antioxidants were blended, melt-granulated, dried, and then pulverized and sieved in a high-speed pulverizer. In this example, 80-mesh powder was selected as the biodegradable powder. The biodegradable powder was mixed with activated carbon (powder, commercially available) at a mass ratio of 4:1 and then placed in a granulation machine to prepare biodegradable granules according to the method in Example 1.

[0082] Example 6:

[0083] Following the method in Example 1, PGA raw materials, PEEK, and antioxidants were blended, melt-granulated, dried, and then pulverized and sieved in a high-speed pulverizer. 90-mesh powder was selected to obtain biodegradable powder. The biodegradable powder, wood flour, and peppermint flavoring were mixed evenly at a mass ratio of 100:20:0.05 and then extruded and granulated in a pellet mill to prepare biodegradable granules according to the method in Example 1.

[0084] Example 7:

[0085] PGA raw material, PEEK and antioxidant were blended according to the method of Example 1, melt-granulated, dried and then crushed and sieved in a high-speed pulverizer to obtain biodegradable powder by selecting 60 mesh powder.

[0086] Weigh out the biodegradable powder and sodium bicarbonate separately at a mass ratio of 20:1, then add 5% of polyethylene glycol PEG4000 to each, mix them evenly to obtain material one and material two. Mix material one and material two evenly, and then use the dry compression method commonly used for effervescent tablets to granulate them in a granulation machine to produce biodegradable granules. The biodegradable granules are cylindrical with a diameter of 6 mm and a height of 4 mm.

[0087] Example 8:

[0088] Biodegradable particles were prepared according to the method in Example 7. PEG4000 was then dissolved in anhydrous ethanol at 50°C to prepare a coating solution (5% concentration), which was sprayed onto the surface of the particles and then dried in an oven.

[0089] Example 9:

[0090] Biodegradable granules were prepared according to the method of Example 1, except that after being crushed and sieved in a high-speed pulverizer, 40-mesh powder was selected as the biodegradable powder and then extruded and granulated in a pellet mill.

[0091] The biodegradable granules produced can meet the basic requirements of excrement treatment materials, such as good water absorption and can be flushed directly into the toilet. However, they are prone to shedding powder during the process of being shaken and clumped together after being used by pets.

[0092] Example 10:

[0093] Biodegradable granules were prepared according to the method of Example 2, except that the formulation ratio of the materials entering the granulation machine was changed so that the biodegradable powder and starch were mixed evenly at a mass ratio of 1:1 and then put into the granulator for extrusion granulation according to the method of Example 2.

[0094] The biodegradable granules produced have a good appearance, good water absorption, and no powder shedding. They quickly clump together after use, but after flushing, they stick to the toilet wall and are not easily washed away by the water flow. It is necessary to increase the water flow or manually remove the granules stuck to the wall. Therefore, they are not suitable for direct flushing into the toilet, but are suitable for collection and composting.

[0095] Comparative Example 1:

[0096] The PGA raw material in Example 1 was replaced with PLA, and the formulation and melt granulation method were the same as in Example 1. Specifically, PLA raw material, PEEK, and antioxidant (antioxidant 168: antioxidant 1010 in a mass ratio of 1:1) were blended in a mass ratio of 100:0.5:0.5, melt-granulated at 180-190℃, and then dried to obtain blended melt-granulated and dried PLA granules.

[0097] After the PLA granules were blended, melt-granulated and dried, they were placed in liquid nitrogen and frozen for 1 minute. Then they were crushed in a crusher to obtain 90-mesh powder. The powder was kept dry and placed in a pelletizing machine. The subsequent manufacturing method was the same as in Example 1.

[0098] The biodegradable particles produced are not easily degraded in water and do not have the ability to regulate acidity or alkalinity.

[0099] Comparative Example 2:

[0100] The PEEK component in Example 1 was removed, and the other manufacturing methods were the same as in Example 1.

[0101] After the biodegradable granules were opened from their sealed packaging and exposed to air, the time it took for the sample to change from its original color and dryness to becoming whitish and sticky was significantly shorter than in Example 1.

[0102] Detection example

[0103] The biodegradable particles (hereinafter referred to as cat litter samples) in the examples and comparative examples were tested using the following methods, and the results are shown in Table 1:

[0104] The method for testing water absorption rate is as follows: Weigh 50g of cat litter sample, put it in a basin, add 100g of distilled water, and after 30 seconds, drain the excess water and weigh the excess water as M. Water absorption rate = (100-M) / 100*100%.

[0105] The method for detecting powder shedding is as follows: Place 200g of cat litter sample in a basin, gently shake the basin for 30 seconds to allow the cat litter in the basin to collide with each other, and observe the amount of powder shedding.

[0106] The method for detecting the particle disintegration state after adding water is as follows: Weigh 10g of cat litter sample into a beaker, add 30g of purified water, let stand for 30 seconds, shake the beaker slightly, and the cat litter sample will deform and break apart, and the powder will shake with the beaker.

[0107] Test method for direct flushing after pet use: Weigh 10g of cat litter sample into a beaker, add 30g of purified water, let stand for 30 seconds, the cat litter sample will deform and crack, and the cat litter sample powder in the water can be easily shaken with the beaker when the beaker is shaken slightly.

[0108] pH testing method: Weigh 20g of cat litter sample into a beaker, add 60g of purified water, let stand for 10 minutes, and then insert a pH meter into the liquid at the top of the beaker for testing.

[0109] Method for detecting the time it takes for cat litter to turn white: Take 200g of cat litter sample and place it in two beakers. Seal one beaker in an aluminum-plastic bag, and place the other beaker in a transparent self-sealing bag (unsealed). Place both beakers in a constant temperature and humidity chamber at 23℃ and 50% RH for several days. Take out the two cat litter samples daily and compare their colors, observing the color change of the unsealed sample relative to the sealed sample. After the cat litter sample turns white, if left for a period of time, the surface will become sticky and unusable. Therefore, the experiment ends when the cat litter sample turns white.

[0110] Table 1

[0111]

[0112]

[0113] In Comparative Example 1, PLA was used instead of PGA. PLA is not easily degraded in water, so it cannot be flushed into the sewage system. In addition, since PLA particles are relatively large after being crushed by a conventional pulverizer, it is difficult to obtain a large amount of powder with a mesh size of 80 or larger, even after freezing and crushing. This increases the steps and difficulty of powder preparation. From this perspective, PLA is not suitable as a raw material for cat litter samples.

[0114] This invention tested the time it took for the biodegradable granules in Examples 1, 9, and Comparative Example 2 to turn white. The whitening times were 23 days for Example 1, 25 days for Example 9, and 15 days for Comparative Example 2. The cat litter sample in Comparative Example 2, which did not contain a crystallization accelerator, turned white after 15 days, almost unusable. This means that its shelf life after opening is relatively short, making it unsuitable for bulk cat litter. In contrast, the biodegradable granules obtained by combining PGA raw materials with a crystallization accelerator in the embodiments of this invention had a whitening time of over 23 days, which is 53% longer than that of Comparative Example 2 without a crystallization accelerator, achieving an unexpected technical effect.

[0115] The inventors believe that the biodegradable granules of this invention have the aforementioned advantages over Comparative Example 2 because the crystallization promoter can accelerate the crystallization rate, resulting in more complete crystallization of the sample during the same cooling process. Degradation usually begins and spreads from amorphous parts; therefore, a well-crystallized sample can slow down the degradation rate, giving the sample a longer service life. As shown in the above embodiments and comparative examples of this invention, the biodegradable granules of this invention have a water absorption rate of over 80%, can be stored for more than 23 days in a normal environment without being sealed, and are all biodegradable. After use, they can be composted and used to make soil conditioners, making them suitable as excrement treatment materials. They can conveniently dispose of pet excrement and effectively turn pet excrement into a valuable resource, demonstrating high application value.

[0116] When the biodegradable granules of this invention are used as pet waste treatment materials (such as cat litter), there are two subsequent treatment methods. The first is to flush them directly into the toilet, eliminating the need for waste sorting. The second is to collect them and, after further processing, use them as a soil conditioner to adjust the pH of saline-alkali soils and increase soil fertility. For ease of use, preferably, they can be both flushed directly and used as a soil conditioner. Using preferred embodiments of this invention, for example, by not adding binders or by adding binders and combining them with other additives (such as deodorizers and disintegrants), as in Examples 1, 4, 5, and 7, superior technical effects are achieved compared to Examples 2, 3, and 10.

[0117] For the biodegradable granules of the present invention, when used as pet excrement (such as cat litter), for ease of cleaning, it is preferable to have slight powder shedding, or even no powder shedding. According to the preferred embodiment of the present invention, by controlling the particle size range of the biodegradable powder in dry powder extrusion granulation, for example, Example 1 achieves a further preferred technical effect compared to Example 10; furthermore, a coating can be added, for example, Example 4 achieves an unexpected technical effect compared to Example 1, and under the condition of a preferred biodegradable powder and binder ratio + disintegrant, for example, Example 7 achieves a further superior technical effect compared to Example 1.

[0118] After optimization of the formulation and process, the samples obtained in Examples 4, 7, and 8 simultaneously possess advantages such as no powder shedding, easy disintegration upon adding water, and easy discharge with water flow. Compared with these three examples, Example 4 has the advantages of simple process and low cost; Examples 7 and 8 have added disintegrants to their formulations, which can disintegrate rapidly when exposed to large amounts of water, making them more suitable for direct flushing into the toilet than Example 4.

[0119] This invention has the advantages of simple process, energy saving and environmental protection, biodegradability, non-clogging of sewage system, and making the most of resources.

[0120] Example 11:

[0121] The aforementioned biodegradable granules, which are used by pets (or livestock farms) and contain animal excrement, are subjected to industrial high-temperature sterilization and composting treatment, as is known in the industry, to remove pathogens, insect eggs, and other harmful substances. This process allows them to be packaged as soil conditioners. The recommended application rate for soil conditioners is 100 kg / acre.

[0122] Example 12:

[0123] Similar to Example 11, after industrial high-temperature sterilization of the treatment material containing animal excrement, agricultural potassium carbonate is added at a ratio of 10:1 by weight, mixed evenly, and then packaged as a soil conditioner.

[0124] The recommended application rate of soil conditioner is 100 kg / mu.

[0125] Both PGA and pet excrement are compostable. PGA degrades to a weakly acidic state, thus adjusting soil pH. Pet excrement, after composting, becomes fertile, increasing soil nutrients. Therefore, the biodegradable granules of this invention are suitable as raw materials for soil conditioners. The resulting soil conditioner possesses both fertility and the ability to adjust soil pH.

[0126] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0127] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0128] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0129] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0130] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0131] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A biodegradable granule comprising a polyglycolic acid resin, a crystallization accelerator, and optional additives, The polyglycolic acid resin is at least one of homopolymer polyglycolic acid and copolymer polyglycolic acid; The crystallization accelerator is selected from high-temperature plastics, and the melting temperature of the high-temperature plastics is more than 20°C higher than the melting temperature of the polyglycolic acid resin.

2. The biodegradable particles according to claim 1, characterized in that: The polyglycolic acid resin is a homopolymer polyglycolic acid; and / or... The melting temperature of the high-temperature plastic is higher than 250°C; preferably, The high-temperature plastic is selected from at least one of PEEK, PPS, PA46, and PA10T; and / or, The crystallization accelerator is derived from powdered high-temperature plastic raw materials, preferably, the high-temperature plastic raw materials are powders of 200 mesh or larger; and / or, Based on parts by weight, the content of the crystallization accelerator is 0.1-1 parts, preferably 0.5-0.8 parts, relative to 100 parts of polyglycolic acid resin.

3. The biodegradable particles according to claim 1, characterized in that: The biodegradable particles are at least one of columnar and spherical shapes, preferably cylindrical. More preferably, when the biodegradable particles are cylindrical, the length of the biodegradable particles is 2-20 mm, preferably 2-10 mm; and the diameter is 2-10 mm, preferably 2-5 mm.

4. The biodegradable particles according to any one of claims 1-3, characterized in that: The additives are divided into melt processing aids and granulation aids, and the biodegradable granules are prepared by the following method: Raw materials including polyglycolic acid resin, crystallization promoter and optional melt processing aid are blended, melt granulated at the melting temperature of the polyglycolic acid resin, and then crushed and sieved to obtain biodegradable powder. The biodegradable powder is then mixed with an optional granulation aid, and granulated by powder extrusion, with optional coating added to obtain the biodegradable granules.

5. The biodegradable particles according to claim 4, characterized in that: The biodegradable powder has a particle size range of 60-90 mesh, preferably 60-80 mesh; and / or, The melt processing aid includes an antioxidant; preferably, the antioxidant is selected from at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 2246, antioxidant CA and antioxidant 626, more preferably at least one of antioxidant 168 and antioxidant 1010.

6. The biodegradable particles according to claim 4, characterized in that: The granulation aid includes one or more of binders, deodorizers, fragrances, and disintegrants; preferably: The binder is selected from at least one of starch, polyvinyl alcohol, polyethylene oxide, polyethylene glycol, alginate, sodium alginate, guar gum, konjac flour, xanthan gum, pullulan, gelatin, polyvinylpyrrolidone, sodium polyacrylate, carbomer, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; and / or, The deodorizing agent is selected from at least one of activated carbon, extraction residue from roasted coffee beans, tea leaves, wood flour, rice husk powder, peanut shell powder, and coffee grounds powder; and / or, The fragrance agent is selected from peppermint essence, lemon essence, anethole, ambroxol, violetin, isobutylquinoline, undecylaldehyde, undecenal, eugenol, octylaldehyde, orange, galacin, carrageenan, citronellol, camphor, coumarin, anise oil, geraniol, geraniol, styrax acetate, cedrol acetate, terpineol acetate, benzyl acetate, linalool acetate, amyl salicylate, white sandalwood, cis-jasmone, citral, citronellol, citronellol, eucalyptol, methyl dihydrojasmone, dihydromyrcenol, diphenyloxide, cinnamyl alcohol. At least one of the following: cedarwood, geranium, terpineol, dynasty ketone, damasone, damasne, thymol, basil, patchouli, vanillin, cyclopentadenin lactone, fructose ester, floppy, hexylcinnamaldehyde, peppermint, neojasmine aldehyde, bergamot, ethyl cyclohexylpropionate, maltol, citrus, muscone, methyl ionone, methyl nonyl acetaldehyde, methyl phenyl acetate, ethyl methyl phenyl glycidyl acid, menthol, eucalyptol, lauryl aldehyde, ethyl butyrate, raspberry ketone, limonene, neolimonene aldehyde, limonene aldehyde, rose ether, and rosemary; and / or, The disintegrant is selected from water-absorbing and swelling disintegrants and / or gas-producing disintegrants, preferably at least one of sodium bicarbonate and sodium carbonate; and / or, The amount of the binder is 0-60 parts by weight, preferably 5-40 parts, relative to 100 parts of biodegradable powder; And / or, the amount of the deodorant used is 0-30 parts, preferably 5-20 parts; And / or, the amount of the flavoring agent is 0-0.05 parts, preferably 0.03-0.05 parts; and / or, the amount of the disintegrant is 0-10 parts, preferably 2-5 parts.

7. A method for preparing biodegradable particles according to any one of claims 1-6, characterized in that, include: Raw materials including polyglycolic acid resin, crystallization promoter and optional melt processing aid are blended, melt granulated at the melting temperature of the polyglycolic acid resin, and then crushed and sieved to obtain biodegradable powder. The biodegradable powder is then mixed with an optional granulation aid, and granulated by powder extrusion, with optional coating added to obtain the biodegradable granules.

8. The preparation method according to claim 7, characterized in that: The polyglycolic acid resin is a polyglycolic acid resin raw material and / or obtained by crushing recycled polyglycolic acid products; And / or, The blending is carried out in a high-speed pulverizer; and / or, The melt granulation conditions include: a temperature of 200-230℃; and / or, The biodegradable powder has a particle size range of 60-90 mesh, preferably 60-80 mesh; and / or, The powder extrusion granulation method is either dry powder extrusion granulation or wet powder extrusion granulation.

9. The preparation method according to claim 7, characterized in that: The step of adding coating includes coating the coating solution onto the particles obtained by extruding and granulating the powder, and then drying to remove the solvent from the coating solution; Preferably, the coating solution comprises a film-forming material and a solvent; more preferably, The film-forming material includes at least one of starch, HPMC cellulose, polyethylene glycol, and PVP, and / or the solvent is selected from water and / or ethanol, and / or the concentration of the film-forming material in the coating solution is 1-10 wt%.

10. The use of any one of the biodegradable particles according to claims 1-6 or any one of claims 7-9 as a material for treating animal excrement.

11. A soil conditioner comprising biodegradable particles according to any one of claims 1-6 or biodegradable particles prepared by any one of claims 7-9, animal excrement, and optionally a soil adjuvant; preferably, the animal excrement is encapsulated in the biodegradable particles.

12. A method for preparing the soil conditioner according to claim 11, comprising subjecting a material including biodegradable particles and animal excrement to high-temperature sterilization and composting treatment, and then optionally adding a soil adjuvant to obtain the soil conditioner; preferably, the soil adjuvant includes at least one of calcium carbonate, wood ash, and chemical fertilizer.

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