A kind of nitrile rubber glove with high filling amount of nano calcium carbonate and the monodisperse nano calcium carbonate slurry with ultra-low calcium ion activity adopted thereby

Abstract

The application discloses a kind of ultra-low calcium ion activity monodisperse nano calcium carbonate slurry, which is composed of monodisperse nano calcium carbonate filter cake, calcium carbonate surface end-capping agent, calcium ion complexing agent, potassium hydroxide solution and water; on this basis, the application also provides a kind of nano calcium carbonate high filling amount butyronitrile latex glove, which is made of butyronitrile latex, casein, cellulose, ultra-low calcium ion activity monodisperse nano calcium carbonate slurry and defoaming agent, mixing additive.The monodisperse nano calcium carbonate slurry disclosed by the application has very low calcium ion activity, and as a filler used in butyronitrile latex glove, it will not cause latex flocculation risk, preventing the stability of butyronitrile product production process from being damaged; and it has good dispersibility in butyronitrile latex, and can play an excellent reinforcing effect in butyronitrile latex glove, obtaining better performance.

Description

Technical Field

[0001] This invention relates to the field of nitrile latex glove production, specifically to nitrile latex gloves with high nano-calcium carbonate filling and their ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry. Background Technology

[0002] Nitrile latex gloves are made primarily from nitrile latex, along with vulcanizing agents, defoamers, and other additives, through a dipping and molding process. The main raw material, nitrile latex, is produced through emulsion polymerization of acrylonitrile and butadiene. Nitrile latex gloves do not cause skin allergies and offer wearing comfort similar to natural latex gloves, making them widely used in pharmaceuticals, cosmetics, semiconductors, and precision electronic components. However, with the further expansion of the nitrile latex glove market in recent years, greater challenges have been posed to its quality and production costs.

[0003] Traditional nitrile latex glove production formulations may include a small amount of water-milled light calcium carbonate, or even no inorganic filler at all. The main reasons are as follows: 1) The addition of inorganic fillers reduces the flexibility and extensibility of nitrile latex gloves, resulting in decreased wearing comfort; 2) The addition of water-milled light calcium carbonate, commonly used in latex production, leads to a decrease in the mechanical properties of the gloves due to excessively large particle size and poor dispersibility; 3) Nano-calcium carbonate, commonly used in coatings and other fields, has high surface energy and is prone to agglomeration, which significantly damages the strength of latex products, making it difficult to apply to latex products; 4) Traditional nano-calcium carbonate has well-developed defects, resulting in a high concentration of calcium ions in its dispersion, which reduces latex stability during latex production and processing, affecting normal production. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a nitrile latex glove with high nano-calcium carbonate filling and the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry used therein, which solves the problems of low inorganic filler addition and poor reinforcement of latex products, local defects and poor production process stability in the prior art.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0006] A high-filling-content nitrile latex glove with nano-calcium carbonate comprises, by weight, 100 parts of nitrile latex, 0.5-4.8 parts of casein, 2.3-3.4 parts of mixed additives, 0.6-1.2 parts of cellulose, 5-25 parts of ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, and 0.1-1.5 parts of defoamer; wherein the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry is an aqueous slurry with monodisperse nano-calcium carbonate as the main effective component.

[0007] Preferably, the mass fraction of the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry is 10 to 15 parts.

[0008] In this invention, the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry comprises, by mass parts: 100 parts monodisperse nano-calcium carbonate filter cake, 0.2-2 parts calcium carbonate surface capping agent, 0.5-1 parts calcium ion complexing agent, 5-10 parts potassium hydroxide solution, and 180-200 parts water; wherein the concentration of potassium hydroxide solution is 5-15 wt%.

[0009] Furthermore, the monodisperse nano-calcium carbonate filter cake has a moisture content of no more than 40%, small calcium carbonate particle size with an average particle size of 50-100 nm, less than 5% of which are larger than 200 nm, exhibits a monodisperse state, and has a specific surface area of ​​19-25 m². 2 / g, with harmful metal element content below 200ppm. The calcium carbonate particles in this monodisperse nano-calcium carbonate filter cake have low surface energy, resulting in good dispersibility when added to nitrile latex; simultaneously, the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry has low calcium ion activity, so adding it to nitrile latex will not cause flocculation risk.

[0010] Furthermore, the calcium carbonate surface capping agent includes one or more of sodium hexametaphosphate, sodium polyacrylate, and sodium methylene bis(naphthalene) sulfonate; the calcium ion complexing agent includes one or more of sodium citrate, aminotrimethylphosphonic acid, disodium ethylenediaminetetraacetate, 4A molecular sieve, 4A zeolite, and montmorillonite.

[0011] In this invention, the nitrile latex is a high-nitrile latex, wherein the acrylonitrile content is approximately 35% to 50% by mass; the casein is commercially available edible casein; the cellulose is hydroxymethyl cellulose; and the defoamer is an organosilicon defoamer.

[0012] In this invention, the mixed additive is an aqueous solution comprising a vulcanizing agent, a vulcanizing activator, an accelerator, a dispersant, and an antioxidant. Specifically, the mixed additive comprises the following components by mass: 100 parts solvent water, 20-40 parts sulfur, 15-25 parts zinc oxide, 5-15 parts accelerator, 0.5-1.5 parts antioxidant, and 3-5 parts dispersant; wherein, sulfur is the vulcanizing agent, and zinc oxide is the vulcanizing activator. The accelerator is one or more of accelerator M, accelerator D, or accelerator PX; the antioxidant is one or more of antioxidant 4020, antioxidant 264, or antioxidant 2246; and the dispersant is dispersant NNO. The components of the mixed additive are dispersed using a high-speed disperser and then ground in a high-speed ball mill or roller mill for 5-6 hours.

[0013] The preparation method of the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry in this invention includes the following steps:

[0014] 1) According to the raw materials and their mass fractions, prepare 100 parts of monodisperse nano calcium carbonate filter cake, 0.2-2 parts of calcium carbonate surface sealing agent, 0.5-1 parts of calcium ion complexing agent, 5-10 parts of potassium hydroxide solution, and 180-200 parts of deionized water;

[0015] 2) Under the condition of 5-30℃, the monodisperse calcium carbonate filter cake is placed in a portion of water and stirred and dispersed (the weight of this portion of water is 1-1.5 times the weight of the monodisperse calcium carbonate filter cake), and dispersed in a high-speed disperser at a linear velocity of 80-120m / min for 15-40min.

[0016] 3) After stirring in step 2), add the remaining water and continue to disperse in a high-speed disperser at a linear velocity of 80-120 m / min for 15-30 min;

[0017] 4) After stirring in step 3), add the calcium carbonate surface sealing agent, calcium ion complexing agent, and potassium hydroxide solution. Disperse the mixture in a high-speed disperser at a linear velocity of 80–120 m / min for 5–10 min to obtain the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry. This ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry is in a slurry state. After centrifugation, take the supernatant and determine the calcium ion concentration, using this concentration as the calcium ion activity data. The calcium ion activity in this monodisperse nano-calcium carbonate slurry is extremely low, below 0.05 mmol / L, and its addition to nitrile latex will not cause flocculation risk.

[0018] The method for preparing this ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry involves surface end-capping of calcium carbonate particles to passivate the surface of the calcium carbonate particles and prevent calcium ions from dissolving in subsequent processing. It also involves adding a calcium ion complexing agent to the slurry to reduce calcium ion activity, thereby ensuring that the slurry as a whole has ultra-low calcium ion activity. Furthermore, the addition of potassium hydroxide solution to the slurry further ensures its process stability for use in latex product manufacturing.

[0019] Furthermore, in step 1), the deionized water is preferably 187 to 194 parts.

[0020] Further, in step 2), the mixture is stirred and dispersed in a high-speed disperser at a linear velocity of 80–120 m / min for 15–40 min; in step 3), the mixture is stirred and dispersed in a high-speed disperser at a linear velocity of 80–120 m / min for 15–30 min; and in step 4), the mixture is stirred and dispersed in a high-speed disperser at a linear velocity of 80–120 m / min for 5–10 min.

[0021] Furthermore, the method for preparing the monodisperse nano-calcium carbonate filter cake includes the following steps:

[0022] S1. A process including calcination, digestion, aging, impurity removal, and carbonation is used to prepare calcium carbonate slurry. The calcination process is as follows: limestone with uniform grain size and a harmful heavy metal content of less than 400 ppm is selected as raw material and calcined to obtain quicklime with an activity range of 250-300 mL. The digestion process is as follows: the quicklime obtained by calcination is digested in hot water at 50-90℃ to obtain lime milk. The aging and impurity removal process is as follows: the lime milk is aged for 24-48 hours and filtered to remove impurities to obtain refined raw slurry. The carbonation process is as follows: water is added to the refined raw slurry to adjust the solid content to 5%-8%, and then carbonation is carried out. The initial carbonation temperature is 10-25℃, the CO2 content is 20%-40%, and carbonation is carried out until the pH of the slurry reaches 9.0-10.0, and then carbonation is stopped to obtain calcium carbonate slurry.

[0023] S2. Add inorganic salt grain surface remodeling agent and organic grain surface remodeling agent to the calcium carbonate slurry obtained in S1, and then under ultrasonic conditions (power density 100-300W / 1000cm³). 3 Under these conditions, a monodisperse calcium carbonate suspension is obtained by keeping it at 120–140℃ for 1–4 hours, which has both fine particle size and low surface energy.

[0024] S3. The monodisperse calcium carbonate suspension obtained in S2 is subjected to secondary carbonation to bring its pH value between 7.0 and 7.3, resulting in a carbonized neutral monodisperse calcium carbonate suspension. The secondary carbonation process is as follows: the calcium carbonate suspension obtained by reconstructing the crystal surface is carbonized at an initial carbonation temperature of 10-25℃ and a CO2 content of 20%-40%. Carbonation continues until the pH value of the slurry is between 7.0 and 7.3. Precise secondary carbonation control is used to avoid under-carbonation leaving residual Ca(OH)2 or over-carbonation forming Ca(HCO3)2, thereby reducing the calcium ion concentration in the product.

[0025] S4. The carbonized neutral monodisperse calcium carbonate obtained in S3 is suspended and dehydrated by hydraulic filtration to obtain a calcium carbonate filter cake. The moisture content of the filter cake is controlled to be no more than 40%, i.e., a monodisperse nano-calcium carbonate filter cake. Filtration and centrifugation can remove excess water, which is beneficial to the processing and transportation of calcium carbonate. At the same time, it can also rapidly reduce other soluble ions present in the solution during the production process, achieving the effect of ultra-low ion activity.

[0026] The monodisperse nano-calcium carbonate filter cake prepared by the above method has an average particle size of 50-100 nm, exhibits a monodisperse state, and has a specific surface area of ​​19-25 m². 2 / g can effectively inhibit agglomeration, thus facilitating dispersion in nitrile latex emulsions and ensuring that nitrile latex gloves maintain excellent performance even with high calcium carbonate content.

[0027] Furthermore, the inorganic grain surface remodeling agent is one or more inorganic salts such as sodium silicate, sodium chloride, aluminum chloride, and zinc sulfate, and the amount used is 0.5% to 3% of the dry weight of calcium carbonate; the organic grain surface remodeling agent is one or more organic compounds such as ethanol, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and disodium ethylenediaminetetraacetate, and the amount used is 1% to 5% of the dry weight of calcium carbonate.

[0028] Based on the above, the present invention also provides a method for preparing nitrile latex gloves, comprising the following steps:

[0029] (1) According to the raw materials and their mass fractions of the present invention, casein, mixing aids, nanocellulose and defoamer are added to nitrile latex and stirred and dispersed evenly to obtain a mixed emulsion;

[0030] (2) Add the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry to the mixture obtained in step (1), stir evenly, and obtain the mixture;

[0031] (3) After cleaning the glove mold, preheat it to 60-70℃, immerse it in coagulant, control the immersion time to 5-10s, after immersion, remove the glove mold, shake off the excess coagulant, and then put it into a 60-70℃ oven for drying time of 4-6min.

[0032] (4) Immerse the glove mold obtained in step (3) into the mixture obtained in step (2) and control the immersion time to 5-10 seconds. Then remove the glove mold and drip off the excess mixture. Then send it into an oven at 60-70℃ and dry it for 4-6 minutes.

[0033] (5) Immerse the glove mold obtained in step (4) in warm water at about 45°C for 10-20 seconds. Then remove the glove mold, shake off excess water, roll the edges, and put it into an oven at 60-70°C for 4-6 minutes.

[0034] (6) Immerse the glove mold obtained in step (5) in a 2% to 10% polyurethane solution and control the immersion time to 5 to 10 seconds. Then remove the glove mold, discard the excess polyurethane solution, and then send it into an oven at 120 to 130°C for 7 to 8 minutes. Demold to obtain a nitrile latex glove with high nano-calcium carbonate filling.

[0035] In preparing monodisperse nano-calcium carbonate filter cake, this invention uses limestone with uniform crystal size and a content of harmful heavy metals such as cadmium, lead, and chromium of less than 400 ppm as raw material. Then, a calcination temperature matching the crystal size is used to obtain quicklime with moderate and uniform activity. This quicklime is then digested and carbonized to obtain a slurry of calcined calcium carbonate. Using limestone with uniform crystal size as the raw material for preparing monodisperse nano-calcium carbonate filter cake allows for adjustment of lime activity through the limestone calcination process, avoiding partial under-burning and over-burning caused by mottled crystals. The good uniformity and moderate activity of the lime facilitate control of the digestion reaction, obtaining a homogeneous lime slurry with controllable properties, thereby enabling control of the subsequent carbonation process and obtaining a slurry of calcium carbonate with the desired particle size and crystal morphology. The content of harmful heavy metals such as cadmium, lead, and chromium in the quicklime is less than 400 ppm, ensuring that the content of harmful heavy metals in the prepared monodisperse nano-calcium carbonate filter cake is less than 200 ppm, guaranteeing the safety of nitrile latex gloves using it as a filler.

[0036] In the preparation of monodisperse nano-calcium carbonate filter cakes, this invention includes a grain surface reconstruction step after carbonization. This step involves adding inorganic and organic surface reconstruction agents and maintaining the temperature under ultrasonic assistance to promote grain surface reconstruction, resulting in more complete crystals, smoother particle surfaces, and reduced surface energy, thus facilitating dispersion. The inorganic surface reconstruction agent promotes crystal development, repairs defects, and makes the crystals more complete; the organic surface reconstruction agent regulates the surface potential of the particles, controls the mutual repulsion of the crystals in water, and prevents adhesion during crystal repair; ultrasonic assistance improves the dispersibility of the calcium carbonate particles. By controlling the grain surface reconstruction temperature, time, and ultrasonic power, this invention controls the average particle size of calcium carbonate particles to 50–100 nm, achieving a highly monodisperse state. This morphology of calcium carbonate particles allows it to exert excellent reinforcing effects as a filler for nitrile latex gloves.

[0037] In this invention, the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry uses monodisperse calcium carbonate filter cake as the main raw material. This filter cake is dispersed in deionized water, and a calcium carbonate surface-sealing agent, a calcium ion complexing agent, and a potassium hydroxide solution as a stabilizer are added to obtain the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry product for nitrile latex gloves described in this invention. Firstly, the monodisperse calcium carbonate filter cake maintains no more than 40% moisture content, preserving a water film and electric double layer structure between the calcium carbonate solid particles. This maximizes the preservation of the surface state and repulsive forces of the calcium carbonate particles, preventing agglomeration. This allows for rapid redispersibility in the aqueous solution during disperser-assisted stirring and maintains stable suspension. More importantly, by surface-sealing the calcium carbonate particles, the particle surface is passivated, preventing the dissolution of calcium ions from the calcium carbonate surface during subsequent processing. Furthermore, the addition of a calcium ion complexing agent to the slurry reduces calcium ion activity, ensuring an overall ultra-low calcium ion activity, below 0.05 mmol / L.

[0038] The nitrile latex gloves with high-filled nano-calcium carbonate produced using the technical solution of this invention utilize a filler (i.e., an ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry) that exhibits excellent aqueous dispersibility and ultra-low calcium ion activity, ensuring the stability of the production process. Its stringent particle size control and good dispersibility in nitrile latex guarantee its excellent reinforcing effect on the nitrile latex gloves. Compared to latex gloves with the same mass of water-milled light calcium carbonate, the nitrile latex gloves prepared by this invention show a 30% increase in tensile strength and a 20% increase in elongation at break. Compared to water-milled light calcium carbonate fillers that achieve the same mechanical properties, the nitrile latex gloves prepared by this invention have a lower formulation cost, reducing the cost by 20%.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. This invention prepares a monodisperse nano-calcium carbonate slurry with ultra-low calcium ion activity as a filler for the nitrile latex gloves of this invention. By strictly controlling the calcium ion concentration, its addition to the nitrile latex gloves does not pose a risk of latex flocculation, thus preventing disruption of the stability of the nitrile product manufacturing process. Furthermore, the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, as a filler, exhibits good dispersibility in nitrile latex and has a finer particle size than water-milled light calcium carbonate. When added to nitrile latex gloves, it provides excellent reinforcement and superior mechanical properties. Compared to latex products with the same mass fraction of water-milled light calcium carbonate, the tensile strength is increased by 30%, and the elongation at break is increased by 20%. Therefore, this invention effectively overcomes the problems of low inorganic filler addition, poor reinforcement effect, and poor production process stability in existing technologies, providing a new approach to resolving the cost-performance contradiction in nitrile latex gloves.

[0041] 2. The nano-calcium carbonate high-filling-content nitrile latex gloves of the present invention have low formulation cost. Compared with adding water-milled light calcium carbonate as a filler to achieve the same mechanical properties, its formulation cost is reduced by 20%. Attached Figure Description

[0042] Figure 1 A scanning electron microscope image of monodisperse nano-calcium carbonate prepared in Example 1;

[0043] Figure 2 Here is a scanning electron microscope image of the monodisperse nano-calcium carbonate prepared in Example 2;

[0044] Figure 3 Here is a scanning electron microscope image of the monodisperse nano-calcium carbonate prepared in Example 3;

[0045] Figure 4 A scanning electron microscope image of calcium carbonate prepared in Comparative Example 1;

[0046] Figure 5 This is a scanning electron microscope image of the calcium carbonate prepared in Comparative Example 2. Specific implementation methods

[0047] 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.

[0048] In this invention, the calcium carbonate surface capping agent, calcium ion complexing agent, organic grain remodeling agent, and inorganic grain remodeling agent are all commercially available analytical grade reagents. In the following examples, sodium polyacrylate is in liquid state, with an effective component greater than 40% and a molecular weight of 3000; polyethylene glycol is PEG-400; and polyvinylpyrrolidone is PVP K30.

[0049] In the following examples, the nitrile latex is a high-nitrile nitrile latex, purchased from Zhejiang Tianchen Adhesive Industry Co., Ltd., and the model is medical nitrile latex TC-N135R.

[0050] In the following examples, the casein is commercially available casein purchased from Gansu Hualing Dairy Co., Ltd., product name: Edible Casein.

[0051] In the following examples, the cellulose is hydroxymethyl cellulose, CAS number 9004-32-4.

[0052] In the following examples, the defoamer is an organosilicone defoamer, purchased from Shanghai Sangjing Chemical Co., Ltd., model DF-963.

[0053] In the following examples, the mixed additives, by weight, consist of 30 parts sulfur, 20 parts zinc oxide, 10 parts accelerator D, 1 part antioxidant 4020, 4 parts dispersant NNO, and 100 parts deionized water. The aforementioned additives were dispersed using a high-speed disperser and then ground in a high-speed ball mill or roller mill for 4 hours. The sulfur was purchased from Linyi Houpu Chemical Co., Ltd., and its product name was rubber sulfur powder. The zinc oxide was purchased from Weifang Aolong Zinc Industry Co., Ltd., and its product name was zinc oxide for rubber and plastics. Accelerator D was diphenylguanidine, CAS number 102-06-7. Antioxidant 4020 was N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, CAS number 793-24-8. Dispersant NNO was sodium methylene bis(naphthalene)sulfonate, CAS number 36290-04-7.

[0054] Example 1

[0055] (1) This embodiment first provides a monodisperse nano calcium carbonate filter cake, and the specific steps of its preparation method are as follows:

[0056] S1. Calcium carbonate slurry is prepared using calcination, digestion, and carbonation processes. The calcination process involves selecting limestone with a grain size of 0.2–0.5 mm and a content of harmful heavy metals such as cadmium, lead, and chromium of less than 400 ppm as raw material, calcining at 900℃ for 2 hours to obtain ideally active quicklime. The digestion process involves digesting the calcined quicklime with water at 90℃ to obtain lime slurry. The aging and impurity removal process involves aging the lime slurry for 24 hours and then filtering to remove impurities to obtain refined raw slurry. The carbonation process involves adding water to the refined raw slurry obtained from digestion to adjust the solid content to 5%, then carbonating at an initial temperature of 25℃ and a CO2 content of 33%, continuing carbonation until the slurry pH reaches 9.0–10.0, thus obtaining calcium carbonate slurry.

[0057] S2. Add 0.5% aluminum chloride, 0.5% ethanol, 1% polyethylene glycol, 0.5% polyvinylpyrrolidone, and 2% sodium dodecylbenzenesulfonate by dry weight of calcium carbonate to the calcium carbonate slurry obtained in S1, and so on, under ultrasonic power density of 300W / 1000cm³. 3 Under the conditions of incubation at 120℃ for 4 hours, dispersion and reconstruction were carried out to obtain a monodisperse calcium carbonate suspension;

[0058] S3. The calcium carbonate suspension obtained in S2 is subjected to secondary carbonation. The initial carbonation temperature is 25℃, the CO2 content is 33%, and the carbonation is carried out until the pH value of the slurry is between 7.0 and 7.3, so as to obtain a carbonized neutral monodisperse calcium carbonate suspension.

[0059] S4. The calcium carbonate slurry obtained in S3 was dehydrated by pressure filtration to obtain a calcium carbonate filter cake with a moisture content of 40%, i.e., a monodisperse calcium carbonate filter cake. A suitable amount of the filter cake was then dried at 105℃ and subjected to composition, specific surface area, microstructure, and particle size analysis. Composition and specific surface area tests were conducted according to the "Analytical Methods for Calcium Carbonate" (GB / T 19281-2014) standard, while microstructure and particle size tests were conducted according to the "Nano Calcium Carbonate" (GB / T 19590-2023) standard. The obtained monodisperse nano calcium carbonate filter cake showed that the content of harmful impurities such as cadmium, lead, barium, mercury, and arsenic was less than 0.0002%, and the total content of harmful impurities was less than 200 ppm; the specific surface area was approximately 19.02 m². 2 / g; from scanning electron microscope images (see Figure 1 It can be clearly seen that the average particle size of the calcium carbonate particles in the obtained monodisperse nano calcium carbonate filter cake is about 100 nm, and the particles larger than 200 nm are less than 5%. The particles are cubic, with a smooth and clean surface, and are in a monodisperse state.

[0060] (2) Based on the above, this embodiment also provides an ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, which is prepared from the following raw materials in the indicated mass ratios: 100 parts monodisperse nano-calcium carbonate filter cake, 1 part sodium polyacrylate, 1 part 4A zeolite, 10 parts 10wt% potassium hydroxide solution, and 188 parts deionized water. The preparation process is as follows: According to the above raw materials and their mass ratios, 100 parts monodisperse nano-calcium carbonate filter cake and 100 parts deionized water are stirred in a high-speed disperser at a stirring speed of 120 m / min for 15 min; the remaining 88 parts deionized water are added, and the mixture is stirred in a high-speed disperser at a stirring speed of 120 m / min for another 15 min; then, sodium polyacrylate, 4A zeolite, and 10wt% potassium hydroxide solution are added according to the above formula, and the mixture is stirred in a high-speed disperser at a stirring speed of 120 m / min for another 5 min, thus obtaining the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry used in this embodiment. At this point, take an appropriate amount of monodisperse nano-calcium carbonate slurry, centrifuge it at 5000 r / min using a high-speed centrifuge, and obtain the supernatant. Use a calcium ion titrator to determine the calcium ion concentration in the supernatant; the calcium ion concentration is 0.044 mmol / L, which is the calcium ion activity. Note: The concentration of free calcium ions dispersed in an aqueous solution is the calcium ion activity. When using the electrode method, taking the supernatant for testing ensures the accuracy of the calcium ion electrode.

[0061] (3) Based on the above, this embodiment also provides a nitrile latex glove with high filling amount of nano-calcium carbonate, which is made of the following raw materials in the following mass ratio: 100 parts of nitrile latex, 2.5 parts of casein, 3.0 parts of mixed additives, 0.9 parts of cellulose, 25 parts of ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, and 1.5 parts of defoamer.

[0062] The preparation method of the nano-calcium carbonate high-filling-content nitrile latex gloves described in this embodiment is as follows:

[0063] (1) According to the above raw materials and their mass fractions, casein, mixing aids, cellulose and defoamer are added to nitrile latex and stirred and dispersed for 0.5 h to obtain a mixture;

[0064] (2) Add the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry to the mixture obtained in step (1) and stir for 0.5 h to obtain a uniformly mixed mixture.

[0065] (3) After cleaning the glove mold, preheat it to 70°C, immerse it in the coagulant, control the immersion time to 5 seconds, after immersion, remove the glove mold, shake off the excess coagulant, and then put it into a 65°C oven for 5 minutes.

[0066] (4) Immerse the glove mold obtained in step (3) into the mixture obtained in step (2) and control the immersion time to 5-10 seconds. Remove the glove mold and let the excess mixture emulsion drip off. Then send it into a 65°C oven and dry it for 5 minutes.

[0067] (5) Immerse the glove mold obtained in step (4) in 45°C warm water for 10 seconds, remove the glove mold, shake off excess water, roll the edges and send it into a 65°C oven for 5 minutes.

[0068] (6) Immerse the glove mold from step (5) in a 2wt% polyurethane solution, control the immersion time to 10s, remove the glove mold, discard the excess polyurethane solution, and then send it into an oven and set the oven temperature to 125℃, controlling the vulcanization time (i.e. drying time) to 7.5min.

[0069] (7) After vulcanization, the nitrile latex gloves with high nano-calcium carbonate filling are obtained by demolding.

[0070] Example 2

[0071] (1) This embodiment first provides a monodisperse nano-calcium carbonate filter cake, the preparation method of which differs from that of Example 1 in that: the digestion temperature in step S1 is 80℃, the aging time is 30h, the solid content of the refined raw pulp in the carbonation process is 8%, the carbonation initiation temperature is 20℃, and the CO2 content is 35%; in step S2, during the crystal surface reconstruction process, 1.5% sodium chloride, 1.5% sodium silicate, 0.5% polyvinyl alcohol, and 0.5% sodium dodecyl sulfate by dry weight of calcium carbonate are added, and the ultrasonic power density is 200W / 1000cm³. 3 Under these conditions, keep warm at 130℃ for 3 hours.

[0072] The monodisperse calcium carbonate filter cake obtained in this example was analyzed for composition, specific surface area, microstructure, and particle size using the same testing methods as in Example 1. The contents of harmful impurities such as cadmium, lead, barium, mercury, and arsenic in the obtained monodisperse nano-calcium carbonate were all less than 0.0002%, and the total content of harmful impurities was less than 200 ppm; the specific surface area was 20.15 m². 2 / g; from SEM images (see Figure 2 It can be clearly seen that the average particle size of the obtained monodisperse nano calcium carbonate particles is about 70 nm, the particles are cubic, and the surface is flat and clean.

[0073] (2) Based on the above, this embodiment also provides an ultra-low calcium ion activity monodisperse nano calcium carbonate slurry, which is prepared from the following raw materials in the following mass ratio: 100 parts monodisperse calcium carbonate filter cake, 2 parts sodium methylene bisnaphthalene sulfonate, 0.5 parts disodium ethylenediaminetetraacetate, 8 parts 10wt% potassium hydroxide solution, and 189.5 parts deionized water. The preparation process is as follows: According to the above raw materials and their mass fractions, 100 parts of monodisperse calcium carbonate filter cake and 150 parts of deionized water are stirred in a high-speed disperser at a stirring speed of 100 m / min for 25 min; the remaining 39.5 parts of deionized water are added, and the mixture is stirred in a high-speed disperser at a stirring speed of 100 m / min for 15 min; then, according to the above formula, sodium methylene bis(naphthalene)sulfonate, disodium ethylenediaminetetraacetate and 10 wt% potassium hydroxide solution are added, and the mixture is stirred in a high-speed disperser at a stirring speed of 100 m / min for 8 min, thus obtaining the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry for nitrile latex gloves described in this embodiment, with a calcium ion activity of 0.015 mmol / L.

[0074] (3) Based on the above, this embodiment also provides a high-filling-content nano-calcium carbonate nitrile latex glove, which is prepared from the following raw materials in the following mass ratio: 100 parts of nitrile latex, 4.8 parts of casein, 3.4 parts of mixed additives, 0.6 parts of cellulose, 15 parts of ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, and 1.0 part of defoamer.

[0075] The preparation method of the nano-calcium carbonate high-filling-content nitrile latex gloves described in this embodiment is as follows:

[0076] (1) According to the above raw materials and their mass fractions, casein, mixing aids, cellulose and defoamer are added to nitrile latex and stirred and dispersed for 0.5 h to obtain a mixture;

[0077] (2) Add the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry to the mixture prepared in step (1) and stir for 0.5 h to obtain a uniformly mixed mixture.

[0078] (3) After cleaning the glove mold, preheat it to 60°C, immerse it in the coagulant, control the immersion time to 10s, after immersion, remove the glove mold, shake off the excess coagulant, and then put it into a 65°C oven for 5min.

[0079] (4) Immerse the glove mold from step (3) into the mixture, control the immersion time to 5-10 seconds, remove the glove mold, let the excess emulsion drip off, and then send it into a 65°C oven for 5 minutes.

[0080] (5) Immerse the glove mold from step (4) in 45°C warm water for 10-20 seconds, remove the glove mold, shake off the water, roll the edges and send it into a 65°C oven for 5 minutes.

[0081] (6) Immerse the glove mold from step (5) in a 10% polyurethane solution for 5 seconds. Remove the glove mold, remove excess coating, and then put it into an oven and set the oven temperature to 125°C for 7.5 minutes.

[0082] (7) After vulcanization, the high-filling-content nitrile latex gloves with nano-calcium carbonate were obtained by demolding.

[0083] Example 3

[0084] (1) This embodiment first provides a monodisperse nano-calcium carbonate filter cake, the preparation method of which differs from that of Example 1 in that: the digestion temperature in step S1 is 50℃, the aging time is 48h, the solid content of the refined raw pulp in the carbonation process is 10%, the carbonation starting temperature is 10℃, and the CO2 content is 40%; in step S2, during the crystal surface reconstruction process, 0.5% sodium chloride, 0.5% sodium silicate, 1% zinc sulfate, and 2% hexadecyltrimethylammonium bromide by dry weight of calcium carbonate are added, and the ultrasonic power density is 100W / 1000cm. 3 Under these conditions, keep warm at 140℃ for 1 hour.

[0085] The monodisperse calcium carbonate filter cake obtained in this example was analyzed for composition, specific surface area, microstructure, and particle size using the same testing methods as in Example 1. The contents of harmful impurities such as cadmium, lead, barium, mercury, and arsenic in the obtained monodisperse nano-calcium carbonate were all less than 0.0002%, and the total content of harmful impurities was less than 200 ppm; the specific surface area was 24.79 m². 2 / g; from SEM images (see Figure 3 It can be clearly seen that the average particle size of the obtained monodisperse nano calcium carbonate particles is about 55 nm, the particles are nearly spherical, and the surface is flat and clean.

[0086] (2) Based on the above, this embodiment also provides an ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, which is prepared from the following raw materials in the following mass ratio: 100 parts monodisperse nano-calcium carbonate filter cake, 0.2 parts sodium hexametaphosphate, 0.5 parts sodium citrate, 5 parts 10% potassium hydroxide solution, and 194 parts deionized water; the preparation process is as follows: according to the aforementioned raw materials and their mass ratios, 100 parts monodisperse calcium carbonate filter cake and 120 parts deionized water are mixed in a high-speed disperser with a stirring line of 80 m / min. Stir at high speed for 40 minutes; add the remaining 74 parts of deionized water, and continue stirring at a high speed of 80 m / min for 30 minutes; then add sodium hexametaphosphate, sodium citrate and 10 wt% potassium hydroxide solution according to the above formula, and continue stirring at a high speed of 80 m / min for 10 minutes to obtain the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry for nitrile latex gloves described in this embodiment, with a calcium ion activity of 0.023 mmol / L.

[0087] (3) Based on the above, this embodiment also provides a nitrile latex glove with high filling amount of nano-calcium carbonate, which is prepared from the following raw materials in the following mass ratio: 100 parts of nitrile latex, 0.5 parts of casein, 2.3 parts of mixed additives, 1.2 parts of cellulose, 5 parts of ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, and 0.1 parts of defoamer.

[0088] The preparation method of the nano-calcium carbonate high-filling-content nitrile latex gloves described in this embodiment is as follows:

[0089] (1) According to the above raw materials and their mass fractions, casein, mixing aids, cellulose and defoamer are added to nitrile latex and stirred and dispersed for 0.5 h to obtain a mixture;

[0090] (2) Add the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry to the mixture prepared in step (1) and stir for 0.5 h to obtain a uniformly mixed mixture.

[0091] (3) After cleaning the glove mold, preheat it to 65°C, immerse it in the coagulant, control the immersion time to 8 seconds, after immersion, remove the glove mold, shake off the excess coagulant, and then put it into a 65°C oven for 5 minutes.

[0092] (4) Immerse the glove mold from step (3) into the mixture, control the immersion time to 5-10 seconds, remove the glove mold, let the excess emulsion drip off, and then send it into a 65°C oven for 5 minutes.

[0093] (5) Immerse the glove mold from step (4) in 45°C warm water for 15 seconds, remove the glove mold, shake off the water, roll the edges and send it into a 65°C oven for 5 minutes.

[0094] (6) Immerse the glove mold from step (5) in a 5wt% polyurethane solution for 8 seconds. Remove the glove mold, remove excess coating, and then put it into an oven. Set the oven temperature to 125°C and control the curing time to 7.5 minutes.

[0095] (7) After vulcanization, the high-filling-content nitrile latex gloves with nano-calcium carbonate were obtained by demolding.

[0096] Example 4

[0097] (1) This embodiment first provides a monodisperse nano calcium carbonate filter cake, which is prepared in the same way as in Example 2.

[0098] (2) Based on the above, this embodiment also provides an ultra-low calcium ion activity monodisperse nano calcium carbonate slurry, which is prepared from the following raw materials in the following mass ratio: 100 parts monodisperse nano calcium carbonate filter cake, 1.2 parts sodium methylene bis(naphthalene) sulfonate, 0.8 parts 4A molecular sieve, 6 parts 10% potassium hydroxide solution, and 192 parts deionized water; the preparation process is as follows: according to the aforementioned raw materials and their mass ratios, 100 parts monodisperse calcium carbonate filter cake and 130 parts deionized water are mixed in a high-speed disperser at a stirring linear speed of 110 m / min. Stir for 20 minutes; add the remaining 62 parts of deionized water, and continue stirring with a high-speed disperser at a stirring speed of 110 m / min for 20 minutes; then add sodium methylene bisnaphthalene sulfonate, 4A molecular sieve and 10 wt% potassium hydroxide solution according to the above formula, and continue stirring with a high-speed disperser at a stirring speed of 110 m / min for 6 minutes to obtain the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry for nitrile latex gloves described in this embodiment, with a calcium ion activity of 0.002 mmol / L.

[0099] (3) Based on the above, this embodiment also provides a high-filling-content nano-calcium carbonate nitrile latex glove, which is prepared from the following raw materials in the following mass ratio: 100 parts of nitrile latex, 3 parts of casein, 2.6 parts of mixed additives, 1.1 parts of cellulose, 10 parts of ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, and 0.7 parts of defoamer.

[0100] The preparation method of the nano-calcium carbonate high-filling-content nitrile latex gloves described in this embodiment is as follows:

[0101] (1) According to the above raw materials and their mass fractions, casein, mixing aids, cellulose and defoamer are added to nitrile latex and stirred and dispersed for 0.5 h to obtain a mixture;

[0102] (2) Add the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry to the mixture prepared in step (1) and stir for 0.5 h to obtain a uniformly mixed mixture.

[0103] (3) After cleaning the glove mold, preheat it to 70°C, immerse it in the coagulant, control the immersion time to 5 seconds, after immersion, remove the glove mold, shake off the excess coagulant, and then put it into a 65°C oven for 5 minutes.

[0104] (4) Immerse the glove mold from step (3) into the mixture, control the immersion time to 5-10 seconds, remove the glove mold, let the excess emulsion drip off, and then send it into a 65°C oven for 5 minutes.

[0105] (5) Immerse the glove mold from step (4) in 45°C warm water for 10 seconds, remove the glove mold, shake off the water, roll the edges and send it into a 65°C oven for 5 minutes.

[0106] (6) Immerse the glove mold from step (5) in an 8 wt% polyurethane solution for 7 seconds. Remove the glove mold, remove excess coating, and then place it in an oven. Set the oven temperature to 125°C and control the curing time to 7.5 minutes.

[0107] (7) After vulcanization, the high-filling-content nitrile latex gloves with nano-calcium carbonate were obtained by demolding.

[0108] Comparative Example 1

[0109] The only difference between Comparative Example 1 and Example 1 is that a commercially available water-milled light calcium carbonate slurry was used to replace the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry in an equal amount for the preparation of nitrile latex gloves. Everything else was the same as in Example 1. The nitrile latex gloves finally obtained in Comparative Example 1 were stiff and had poor mechanical properties.

[0110] Comparative Example 2

[0111] The only difference between Comparative Example 2 and Example 1 is that, in the preparation of the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, an equal amount of deionized water was used to replace 10 wt% potassium hydroxide solution, and then this ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry was used to prepare nitrile latex gloves. Everything else was the same as in Example 1.

[0112] In Comparative Example 2, because no 10wt% potassium hydroxide solution was added, the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry was added to the nitrile latex. After stirring and mixing evenly, the latex flocculated after standing for 1 hour, and qualified nitrile latex gloves could not be obtained.

[0113] Comparative Example 3

[0114] The only difference between Comparative Example 3 and Example 1 is that: instead of using monodisperse nano-calcium carbonate filter cake, the neutral monodisperse calcium carbonate suspension obtained after secondary carbonization was directly used to prepare an ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry, and then the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry was used to prepare nitrile latex gloves. All other steps were the same as in Example 1.

[0115] Comparative Example 3 failed to remove soluble ions from the slurry by pressure filtration. When the slurry was added to nitrile latex and stirred evenly, it was left to stand for 2 hours, resulting in latex flocculation and making it impossible to obtain qualified nitrile latex gloves.

[0116] Comparative Example 4

[0117] Comparative Example 4 has the same formulation as Example 1, except that the preparation method of the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry differs from that of Example 1. The preparation process is as follows: 100 parts of monodisperse nano-calcium carbonate filter cake are directly added to 188 parts of deionized water, and stirred for 30 minutes at a stirring speed of 120 m / min using a high-speed disperser. After stirring evenly, 1 part of sodium polyacrylate, 1 part of 4A zeolite, and 10 parts of 10 wt% potassium hydroxide solution are added according to the ingredient ratio, and stirring is continued at a stirring speed of 120 m / min for 5 minutes to obtain the ultra-low calcium ion activity monodisperse calcium carbonate slurry used in Comparative Example 4. This ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry is then used to prepare nitrile latex gloves. Everything else is the same as in Example 1.

[0118] Comparative Example 4 lacked a high-concentration stirring step, resulting in poor dispersion of calcium carbonate. When added to nitrile latex, the resulting nitrile latex glove product exhibited poor mechanical properties.

[0119] Comparative Example 5

[0120] The only difference between Comparative Example 5 and Example 3 is that no inorganic grain surface remodeling agent was added in the preparation method of the monodisperse nano-calcium carbonate filter cake, and the resulting product's microstructure is shown in [see figure]. Figure 4 Then, it is used to prepare monodisperse nano-calcium carbonate slurry with ultra-low calcium ion activity, and further to prepare nitrile latex gloves.

[0121] Comparative Example 5, due to the absence of an inorganic grain surface remodeling agent, had a rough surface of calcium carbonate grains, resulting in connections between particles and relatively poor dispersion. When added to nitrile latex, the calcium carbonate particles exhibited poor dispersion in the latex, leading to white spots on the appearance of the prepared nitrile latex gloves and poor mechanical properties.

[0122] Comparative Example 6

[0123] The only difference between Comparative Example 6 and Example 3 is that no organic crystal surface remodeling agent was added in the preparation method of the monodisperse nano-calcium carbonate filter cake, and the resulting product's microstructure is shown in [the figure]. Figure 5 Then, it is used to prepare monodisperse nano-calcium carbonate slurry with ultra-low calcium ion activity, and further to prepare nitrile latex gloves.

[0124] Comparative Example 6, because no organic grain surface remodeling agent was added, had a clean calcium carbonate grain surface, but the dispersion between particles was still relatively poor, and the particles also formed connections. When it was added to nitrile latex, the calcium carbonate particles were poorly dispersed in the latex, and the prepared nitrile latex glove products had white spots on their appearance and poor mechanical properties.

[0125] Comparative Example 7

[0126] The only difference between Comparative Example 7 and Example 3 is that no surface capping agent sodium hexametaphosphate was added when preparing the monodisperse nano calcium carbonate slurry, and the calcium ion activity of the resulting monodisperse nano calcium carbonate slurry was 0.52 mmol / L; then the monodisperse nano calcium carbonate slurry was used to prepare nitrile latex gloves.

[0127] When preparing the monodisperse nano-calcium carbonate slurry with ultra-low calcium ion activity in Comparative Example 7, because no calcium carbonate surface capping agent was added, the calcium ion activity was high. When it was added to nitrile latex, latex flocculation occurred after stirring and mixing for 10 minutes, and qualified nitrile latex gloves could not be obtained.

[0128] Comparative Example 8

[0129] The only difference between Comparative Example 8 and Example 4 is that no calcium ion complexing agent 4A molecular sieve was added when preparing the monodisperse nano calcium carbonate slurry, and the calcium ion activity of the obtained monodisperse nano calcium carbonate slurry was 1.08 mmol / L; then the monodisperse nano calcium carbonate slurry was used to prepare nitrile latex gloves.

[0130] Comparative Example 8, lacking a calcium ion complexing agent, exhibited high calcium ion activity. When added to nitrile latex and stirred for 5 minutes, latex flocculation occurred, making it impossible to produce qualified nitrile latex gloves.

[0131] The performance of nitrile latex gloves prepared by the above examples, comparative examples, and those with commercially available water-milled light calcium carbonate was tested. Ten gloves were taken from each group. The nitrile latex gloves were type M, weighing approximately 7g each. The tensile properties of the nitrile latex gloves were tested according to the requirements of the American standard ASTM D3577-19. Comparative examples 3, 7, and 8 could not be prepared into glove samples due to latex flocculation, therefore no performance evaluation was conducted on these samples.

[0132] Table 1. Performance of nitrile latex gloves prepared in each example and comparative example.

[0133]

[0134]

[0135] Note: The calcium carbonate slurry refers to the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry prepared in the examples, or the calcium carbonate slurry prepared in the comparative examples, or commercially available water-milled light calcium carbonate.

[0136] As shown in Table 1, the tensile strength of the nitrile latex gloves prepared in the embodiments of the present invention before aging is 22-29 MPa, and the elongation is 664%-790%; the tensile strength after aging is 21-28 MPa, and the elongation is 662%-787%. Among them, when the amount of calcium carbonate added was 5 phr, compared with the addition of commercially available water-milled light calcium carbonate, the tensile strength and elongation of the nitrile latex gloves prepared in Example 3 were much higher than the requirements of ASTM D3577-19 standard before and after aging (in this standard, before aging: minimum tensile strength 17 MPa, minimum elongation 650%; after aging: minimum tensile strength 12 MPa, minimum elongation 490%). While the nitrile latex gloves prepared with the addition of commercially available water-milled light calcium carbonate maintained a good level of tensile strength, their elongation was already very close to the minimum elongation required by the standard. Therefore, it can be clearly seen that the nitrile latex gloves prepared with the addition of commercially available water-milled light calcium carbonate had poor softness, which is also the direct reason why the amount of commercially available water-milled light calcium carbonate added to the nitrile latex glove production formula cannot be increased. As the amount of the ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry prepared by this invention is further increased (see Examples 4 and 2, with addition amounts of 10 phr and 15 phr respectively), the tensile strength and elongation are still far higher than the requirements of the ASTM D3577-19 standard. When the amount is further increased to 25 phr (see Example 1), the elongation of the nitrile latex gloves decreases significantly, but still meets the requirements of the ASTM D3577-19 standard, and the mechanical properties are basically the same as those of nitrile latex gloves made with commercially available water-milled light calcium carbonate products with 5 phr added.

[0137] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A monodisperse nano-calcium carbonate slurry with ultra-low calcium ion activity, characterized in that, The raw material composition, by mass parts, includes 100 parts of monodisperse nano-calcium carbonate filter cake, 0.2-2 parts of calcium carbonate surface sealing agent, 0.5-1 parts of calcium ion complexing agent, 5-10 parts of potassium hydroxide solution, and 180-200 parts of water; wherein the concentration of potassium hydroxide solution is 5-15 wt%. The monodisperse nano-calcium carbonate filter cake has a moisture content of no more than 40%, the average particle size of the calcium carbonate particles is between 50 and 100 nm, and the specific surface area of ​​the powder is 19 to 25 m². 2 / g, particles larger than 200 nm are less than 5%, and they are in a monodisperse state; The calcium ion activity of the monodisperse nano-calcium carbonate slurry, based on the calcium ion concentration in the supernatant, is less than 0.05 mmol / L. A method for preparing ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry includes the following steps: 1) Prepare 100 parts of monodisperse nano calcium carbonate filter cake, 0.2-2 parts of calcium carbonate surface sealing agent, 0.5-1 parts of calcium ion complexing agent, 5-10 parts of potassium hydroxide solution, and 180-200 parts of water according to the raw materials and their mass fractions. 2) Under the condition of 5~30℃, the monodisperse nano calcium carbonate filter cake is placed in a portion of water and stirred to disperse; wherein, in this step, the weight of this portion of water is 1~1.5 times the weight of the monodisperse calcium carbonate filter cake; 3) After stirring in step 2), add the remaining water and continue stirring to disperse; 4) After stirring in step 3), add calcium carbonate surface sealing agent, calcium ion complexing agent and potassium hydroxide solution and stir to disperse, and the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry can be obtained. The calcium carbonate surface capping agent includes one or more of sodium hexametaphosphate, sodium polyacrylate, and sodium methylene bis(naphthalene) sulfonate; the calcium ion complexing agent includes one or more of sodium citrate, aminotrimethylphosphonic acid, disodium ethylenediaminetetraacetate, molecular sieve, and montmorillonite.

2. The ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry according to claim 1, characterized in that, The method for preparing the monodisperse nano-calcium carbonate filter cake includes the following steps: S1. A process including calcination, digestion, aging, impurity removal, and carbonation is used to prepare calcium carbonate slurry. The calcination process is as follows: limestone with uniform grain size and a harmful heavy metal content of less than 400 ppm is selected as raw material and calcined to obtain quicklime with an activity range of 250-300 mL. The digestion process is as follows: the quicklime obtained by calcination is digested in hot water at 50-90℃ to obtain lime milk. The aging and impurity removal process is as follows: the lime milk is aged for 24-48 h and filtered to remove impurities to obtain refined raw slurry. The carbonation process is as follows: water is added to the refined raw slurry to adjust the solid content to 5%-8%, and then carbon dioxide is introduced for carbonation. The initial carbonation temperature is 10-25℃, the CO2 content is 20%-40%, and carbonation is carried out until the pH of the slurry reaches 9.0-10.0, and then carbonation is stopped to obtain calcium carbonate slurry. S2. Add inorganic grain surface remodeling agent and organic grain surface remodeling agent to the calcium carbonate slurry obtained in S1, and then keep it at 120~140℃ for 1~4 h under ultrasonic conditions to obtain monodisperse calcium carbonate suspension; S3. The monodisperse calcium carbonate suspension obtained in S2 is subjected to secondary carbonation. The initial temperature of secondary carbonation is 10~25℃, the CO2 content is 20%~40%, and carbonation is carried out until the pH value of the slurry is between 7.0 and 7.3, so as to obtain a carbonized neutral monodisperse calcium carbonate suspension. S4. The carbonized neutral monodisperse calcium carbonate obtained in S3 is suspended and dehydrated by hydraulic filtration to obtain a calcium carbonate filter cake. The moisture content of the filter cake is controlled to be no more than 40%, which is a monodisperse nano calcium carbonate filter cake.

3. The ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry according to claim 2, characterized in that, The inorganic grain surface remodeling agent is one or more of sodium silicate, sodium chloride, aluminum chloride, and zinc sulfate, and the amount used is 0.5% to 3% of the dry weight of calcium carbonate; the organic grain surface remodeling agent is one or more of ethanol, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and disodium ethylenediaminetetraacetate, and the amount used is 1% to 5% of the dry weight of calcium carbonate.

4. The method for preparing an ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry according to claim 1, 2, or 3, characterized in that, Includes the following steps: 1) Prepare 100 parts of monodisperse nano calcium carbonate filter cake, 0.2-2 parts of calcium carbonate surface sealing agent, 0.5-1 parts of calcium ion complexing agent, 5-10 parts of potassium hydroxide solution, and 180-200 parts of water according to the raw materials and their mass fractions. 2) Under the condition of 5~30℃, the monodisperse nano calcium carbonate filter cake is placed in a portion of water and stirred to disperse; wherein, in this step, the weight of this portion of water is 1~1.5 times the weight of the monodisperse calcium carbonate filter cake; 3) After stirring in step 2), add the remaining water and continue stirring to disperse; 4) After stirring in step 3), add calcium carbonate surface capping agent, calcium ion complexing agent and potassium hydroxide solution and stir to disperse, and the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry can be obtained.

5. The method for preparing an ultra-low calcium ion activity monodisperse nano-calcium carbonate slurry according to claim 4, characterized in that, In step 2), the mixture is stirred and dispersed in a high-speed disperser at a linear velocity of 80-120 m / min for 15-40 min; in step 3), the mixture is stirred and dispersed in a high-speed disperser at a linear velocity of 80-120 m / min for 15-30 min; in step 4), the mixture is stirred and dispersed in a high-speed disperser at a linear velocity of 80-120 m / min for 5-10 min.

6. A nitrile latex glove with high nano-calcium carbonate filling, characterized in that, The raw materials, by mass parts, include: 100 parts of nitrile latex, 0.5-4.8 parts of casein, 0.6-1.2 parts of cellulose, 5-25 parts of the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry as described in claim 1, 2, or 3, 0.1-1.5 parts of defoamer, and 2.3-3.4 parts of mixed additives; wherein, the mixed additives are an aqueous solution including vulcanizing agent, vulcanizing activator, accelerator, dispersant, and antioxidant.

7. The nano-calcium carbonate high-filling-content nitrile latex glove according to claim 6, characterized in that, The mixed additive comprises the following components by mass: 100 parts solvent water, 20-40 parts sulfur, 15-25 parts zinc oxide, 5-15 parts accelerator, 0.5-1.5 parts antioxidant, and 3-5 parts dispersant; wherein, sulfur is a vulcanizing agent and zinc oxide is a vulcanizing activator.

8. The nano-calcium carbonate high-filling-content nitrile latex glove according to claim 6, characterized in that, The nitrile latex is high in acrylonitrile, wherein the acrylonitrile content is 35%~50% by mass; the casein is commercially available edible casein; the cellulose is hydroxymethyl cellulose; and the defoamer is an organosilicon defoamer.

9. The method for preparing the nitrile latex gloves with high nano-calcium carbonate filling as described in claim 6, characterized in that, Includes the following steps: (1) According to the raw materials and their mass fractions as described in claim 6, casein, mixing aid, cellulose and defoamer are added to nitrile latex and stirred and dispersed evenly to obtain a mixed emulsion; (2) Add the ultra-low calcium ion activity monodisperse nano calcium carbonate slurry to the mixture obtained in step (1), stir evenly, and obtain the mixture; (3) After cleaning the glove mold, preheat it to 60~70℃, immerse it in coagulant, control the immersion time to 5~10 s, after immersion, take out the glove mold, shake off the excess coagulant, and then put it into a 60~70℃ oven for drying time of 4~6 min. (4) Immerse the glove mold obtained in step (3) into the mixture obtained in step (2), control the immersion time to be 5~10 s, then lift out the glove mold and drip off the excess mixture, and then send it into an oven at 60~70℃ for drying time of 4~6 min; (5) Immerse the glove mold obtained in step (4) in warm water at 40~50℃ for 10~20 s, then remove the glove mold, shake off excess water, roll the edges and send it into an oven at 60~70℃ for 4~6 min. (6) Immerse the glove mold obtained in step (5) into the polyurethane solution, control the immersion time to be 5~10 s, then remove the glove mold, discard the excess polyurethane solution, and then send it into an oven at 120~130℃ for drying time of 7~8 min. Demold to obtain a nitrile latex glove with high nano-calcium carbonate filling; wherein, the polyurethane solution is an aqueous emulsion with a concentration of 2~10 wt%, and the molecular weight of polyurethane is in the range of 1000~10000.

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