Special calcium carbonate for sanitary material and its preparation method

Abstract

The application discloses a preparation method of special calcium carbonate for sanitary materials, which comprises the following steps: (1) synthesizing a grinding aid: mixing polyhexamethylene guanidine hydrochloride PHMG and glycidyl methacrylate GMA, and reacting under heating conditions to obtain an antibacterial modifier GPHMG, then stirring and emulsifying the antibacterial modifier with an emulsifier and triethanolamine to obtain the grinding aid; (2) adding heavy calcium carbonate raw materials into a roller mill, adding the grinding aid to grind, obtaining a mixture; and finely grading the mixture to obtain powder with D90 of 7-8 microns and D50 of 3-4 microns as the special heavy calcium carbonate raw material for sanitary materials to enter an activation unit for activation treatment, thereby obtaining the special calcium carbonate for sanitary materials. The application further discloses the special calcium carbonate for sanitary materials prepared by the preparation method. The application can prepare the calcium carbonate product with antibacterial performance, realizes the development of the special pore-forming agent for sanitary materials, has good "bacteria isolation" performance, and has a wide market prospect.

Description

Technical Field

[0001] This invention belongs to the field of surface modification technology of heavy calcium carbonate, specifically relating to a special calcium carbonate for sanitary materials and its preparation method. Background Technology

[0002] With globalization, the demand for disposable hygiene products, such as diapers and incontinence pads, is constantly increasing in more and more countries and regions. In China, the demand for diapers and incontinence pads used by the elderly is bound to grow rapidly. Addressing the specific needs of the elderly, diapers and incontinence pads used by them require higher breathability and greater tensile strength. Calcium carbonate, used as a filler in diapers and incontinence pads, plays a crucial role in achieving both breathability and tensile strength. To meet this future market demand, it is necessary to develop high-end calcium carbonate specifically for hygiene materials that offers high breathability and high tensile strength.

[0003] According to MarketsandMarkets, the global market for breathable membranes (a type of sanitary material) is projected to grow at an annual rate of over 8.5% from 2016 to 2024. my country has the largest market demand, but the manufacturing technology, equipment, and key raw materials (porogens for sanitary materials - calcium carbonate powder) are monopolized by foreign companies such as Omia and Engel.

[0004] Furthermore, as the novel coronavirus places new demands on the protective capabilities of medical protective equipment, compared with foreign standards for medical protective clothing (such as EN14126-2003), domestic standards lack tests for microbial penetration (such as GB19082-2009). With the formulation and implementation of higher-level standards, medical protective equipment has new requirements for "porogens," such as requiring narrower particle size distribution, finer particle size, and higher activation rate. Currently, domestic calcium carbonate products generally have a coarse particle size or an excessively wide and unstable distribution, making it difficult to produce products with a particle size distribution width of d97≤10μm and a small width (width is expressed as distribution span, distribution width = D90 / D50, requiring a span ≤2.4). Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing calcium carbonate for sanitary materials. This invention can prepare calcium carbonate products with antibacterial properties, realize the development of pore-forming agents for sanitary materials, have good "bacterial barrier" performance, and have broad market prospects.

[0006] To solve the above technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing calcium carbonate for sanitary materials includes the following steps:

[0008] (1) Synthesis of grinding aid: Polyhexamethylene guanidine hydrochloride (PHMG) is mixed with glycidyl methacrylate (GMA) and reacted under heating conditions to obtain antibacterial modifier (GPHMG). Then, it is emulsified with emulsifier and triethanolamine to obtain grinding aid.

[0009] (2) Add the heavy calcium carbonate raw material to a roller mill, add grinding aid and grind to obtain a mixture;

[0010] (3) The mixture is finely graded to obtain powder with D90 of 7-8 μm and D50 of 3-4 μm. This powder is used as a raw material for heavy calcium carbonate for sanitary materials and is then activated in the activation unit.

[0011] Preferably, in step (1), the weight ratio of polyhexamethylene guanidine hydrochloride to glycidyl methacrylate is 40-60:40-60.

[0012] Preferably, in step (1), the weight ratio of antibacterial modifier to emulsifier is 40-50:50-60.

[0013] Preferably, in step (1), the temperature is heated to 50-60°C.

[0014] Preferably, in step (1), the amount of triethanolamine added is 20-30% of the weight of the grinding aid.

[0015] Preferably, in step (2), the roller mill is an ultrafine vertical roller mill with a material layer thickness of 4-5 cm and an internal pressure of 6-7 MPa.

[0016] Preferably, in step (2), the amount of grinding aid added is 0.5 to 0.7% of the weight of the heavy calcium carbonate raw material.

[0017] Preferably, in step (3), the classifier rotation speed is 2300-2500 r / min.

[0018] Preferably, in step (3), stearic acid is used as a surface modifier for activation treatment. It is sprayed in via atomization at a pressure of 0.3 to 0.7 MPa, at a temperature of 90 to 100°C, and for a time of 3 to 5 minutes.

[0019] The present invention also provides a method for preparing the above-mentioned calcium carbonate for sanitary materials.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention uses polyhexamethylene guanidine hydrochloride as the main antibacterial active ingredient. By reacting it with glycidyl methacrylate under certain conditions with a ring-opening reaction, an antibacterial modifier with polymerizable double bonds at the end groups can be obtained. When reacted with the grinding aid monomer triethanolamine in the presence of an emulsifier, a functional grinding aid can be synthesized. This grinding aid is then ground together with calcium carbonate, and through physical coating, a calcium carbonate product with antibacterial properties can be obtained. This product can then be applied to sanitary materials, providing excellent antibacterial effects and reducing the production cost of sanitary materials. Detailed Implementation

[0022] To facilitate a better understanding of the present invention, the following examples are provided. These examples fall within the scope of protection of the present invention, but do not limit the scope of protection of the present invention.

[0023] Example 1

[0024] A method for preparing calcium carbonate for sanitary materials includes the following steps:

[0025] (1) Synthesizing grinding aid: Polyhexamethylene guanidine hydrochloride (PHMG) and glycidyl methacrylate (GMA) are mixed at a weight ratio of 40:60 and heated to 50°C to react and obtain antibacterial modifier GPHMG. Then, it is mixed with emulsifier at a weight ratio of 50:50 and 20% of the weight of the grinding aid is added. The mixture is stirred and emulsified to obtain the grinding aid.

[0026] (2) Add the heavy calcium carbonate raw material to the ultrafine vertical roller mill, add grinding aid at 0.5% of the weight of the heavy calcium carbonate raw material, control the material layer thickness to 4cm, and the pressure inside the roller mill to 6MPa for grinding to obtain a mixture.

[0027] (3) The mixture is finely graded. The fine grading is carried out by grading rotor blades with a 30° angle combined with the air seal design of the grading machine. The grading machine speed is 2300r / min. Powder with D90 of 7~8μm and D50 of 3~4μm is collected as heavy calcium carbonate raw material for sanitary materials and enters the activation unit for activation treatment. Stearic acid is used as a surface modifier and is atomized and sprayed in using an atomization system with an atomization pressure of 0.3MPa. A gas combustion furnace frequency conversion heating system is used to adjust the minimum gas flow rate to 10% without extinguishing it. The activation temperature is controlled at 90℃ and the activation time is 5min.

[0028] Example 2

[0029] A method for preparing calcium carbonate for sanitary materials includes the following steps:

[0030] (1) Synthesizing grinding aid: Polyhexamethylene guanidine hydrochloride (PHMG) and glycidyl methacrylate (GMA) are mixed at a weight ratio of 50:50 and heated to 55°C to react and obtain antibacterial modifier GPHMG. Then, it is mixed with emulsifier at a weight ratio of 50:50 and 25% of the weight of the grinding aid is added. The mixture is stirred and emulsified to obtain the grinding aid.

[0031] (2) Add the heavy calcium carbonate raw material to the ultrafine vertical roller mill, add grinding aid at 0.6% of the weight of the heavy calcium carbonate raw material, control the material layer thickness to 4.5cm, and the pressure inside the roller mill to 6.5MPa, and grind to obtain a mixture.

[0032] (3) The mixture is finely graded. The fine grading is carried out by grading rotor blades with a 38° angle combined with the air seal design of the grading machine. The grading machine speed is 2400 r / min. Powder with D90 of 7-8 μm and D50 of 3-4 μm is collected as heavy calcium carbonate raw material for sanitary materials and enters the activation unit for activation treatment. Stearic acid is used as a surface modifier and is atomized and sprayed in using an atomization system with an atomization pressure of 0.5 MPa. A gas combustion furnace frequency conversion heating system is used to adjust the minimum gas flow rate to 10% without extinguishing it. The activation temperature is controlled at 95℃ and the activation time is 4 min.

[0033] Example 3

[0034] A method for preparing calcium carbonate for sanitary materials includes the following steps:

[0035] (1) Synthesizing grinding aid: Polyhexamethylene guanidine hydrochloride (PHMG) and glycidyl methacrylate (GMA) are mixed at a weight ratio of 60:40 and heated to 60°C to react and obtain antibacterial modifier GPHMG. Then, it is mixed with emulsifier at a weight ratio of 40:60 and 30% of the weight of the grinding aid is added. The mixture is stirred and emulsified to obtain the grinding aid.

[0036] (2) Add the heavy calcium carbonate raw material to the ultrafine vertical roller mill, add grinding aid at 0.7% of the weight of the heavy calcium carbonate raw material, control the material layer thickness to 5cm, and the pressure inside the roller mill to 7MPa for grinding to obtain a mixture.

[0037] (3) The mixture is finely graded. The fine grading is carried out by grading rotor blades with a 40° angle combined with the air seal design of the grading machine. The grading machine speed is 2500 r / min. Powder with D90 of 7-8 μm and D50 of 3-4 μm is collected as heavy calcium carbonate raw material for sanitary materials and enters the activation unit for activation treatment. Stearic acid is used as a surface modifier and is atomized and sprayed in using an atomization system with an atomization pressure of 0.7 MPa. A gas combustion furnace frequency conversion heating system is used to adjust the minimum gas flow rate to 10% without extinguishing it. The activation temperature is controlled at 100℃ and the activation time is 3 min.

[0038] Comparative Example 1

[0039] The process is basically the same as in Example 2, except that glycidyl methacrylate (GMA) and triethanolamine were not added; step (1) is: polyhexamethylene guanidine hydrochloride (PHMG) is stirred and emulsified with an emulsifier to obtain the grinding aid.

[0040] Comparative Example 2

[0041] The process is basically the same as in Example 2, except that triethanolamine was not added. Step (1) is as follows: polyhexamethylene guanidine hydrochloride (PHMG) and glycidyl methacrylate (GMA) are mixed and reacted under heating conditions to obtain an antibacterial modifier. Then, the antibacterial modifier and emulsifier are stirred and emulsified to obtain a grinding aid.

[0042] Comparative Example 3

[0043] The process is basically the same as in Example 2, except that glycidyl methacrylate (GMA) was not added; step (1) is: polyhexamethylene guanidine hydrochloride (PHMG) is stirred and emulsified with emulsifier and triethanolamine to obtain the grinding aid.

[0044] Performance testing experiment

[0045] Experiment 1: Investigating the effects of different compounding ratios of GPHMG and emulsifier on grinding efficiency and product antibacterial properties.

[0046] The ratio of GPHMG to emulsifier determines the grinding efficiency and the antibacterial properties of the special calcium carbonate. Grinding efficiency is characterized by power consumption per ton of product; the lower the power consumption per ton of product, the higher the grinding efficiency. The antibacterial properties are characterized by the time it takes for the product to begin growing mold in a proliferative environment. Based on Example 2, the ratio of GPHMG to emulsifier was changed, and the power consumption per ton of product and the mold growth time in a proliferative environment were recorded. The experimental data are shown in the table below:

[0047] Table 1

[0048] Serial Number GPHMG emulsifier Electricity consumption per ton of product (kWh / t) Antibacterial properties (h) Comprehensive judgment 1 80 20 96.2 192 Difference 2 70 30 86.1 175 Poor 3 60 40 78.2 153 Poor 4 50 50 75.6 139 better 5 40 60 72.5 113 better 6 30 70 70.6 90 Poor 7 20 80 69.8 53 Difference

[0049] As can be seen from Table 1, different compounding ratios of GPHMG and emulsifier have a significant impact on grinding efficiency and the antibacterial properties of special calcium carbonate. Among them, the ratios of 50:50 and 40:60 are the most ideal.

[0050] Experiment 2: Investigating the effect of different classifier speeds on the particle size distribution of calcium carbonate for sanitary materials.

[0051] Based on Example 2, the rotation speed of the classifier was changed, and the D90 and D50 values ​​of the product particle size were measured simultaneously using a laser particle size analyzer. The distribution width was calculated based on D90 / D50. The test results are shown in Table 2.

[0052] Table 2

[0053]

[0054]

[0055] As can be seen from Table 2, the rotation speed of the classifier has a significant impact on the particle size and distribution width of the product. The most suitable rotation speed for the classifier is 2300-2500 rpm. Within this speed range, the distribution width can be ensured to be below 2.3, which meets the particle size distribution requirements of calcium carbonate for sanitary materials. Too high or too low a rotation speed will result in unqualified products.

[0056] Experiment 3: Investigating the effect of activation parameters on product modification.

[0057] Based on Example 2, the atomization pressure was varied, and the activation rate of the product was determined according to GB / T 19281-2014 Calcium Carbonate Analysis Method 3.19. The activation rate fluctuation was calculated by measuring the same sample at least three times, and the impact on the system was evaluated to determine the overall effect. The experimental results are shown in Table 3:

[0058] Table 3

[0059]

[0060] The activation temperature and the atomization degree of stearic acid are the factors that have the greatest impact on the activation degree. Too high a temperature will affect the color of the product, while too low a temperature will reduce the flowability of the powder, thereby reducing the uniformity of the activator's coating on the powder. Given a fixed temperature, the finer the atomization, the more uniform the coating of the powder, but too high an atomization pressure will affect the vacuum degree of the system.

[0061] As can be seen from Table 3, the system is stable at atomization pressures of 0.3 and 0.4 MPa, but the activation rate is low and does not meet the requirements for calcium carbonate for sanitary materials. Although the activation rate meets the requirements at atomization pressures of 0.6 and 0.7 MPa, positive pressure occurs, making the system unstable and prone to clogging. Therefore, an atomization pressure of 0.5 MPa is the best choice, as it provides high atomization intensity, meaning that the modified agent particles become smaller and more dispersed, and the activation rate reaches over 95%.

[0062] Experiment 4: Comparison of the effects of glycidyl methacrylate and triethanolamine used alone and in combination in grinding aids.

[0063] Calcium carbonate was prepared according to the methods of Example 2 and Comparative Examples 1-3. The power consumption per ton of product and the time for mold growth in an environment prone to bacterial growth were recorded, and the product activation rate was determined. The experimental results are shown in Table 4.

[0064] Table 4

[0065] Group Electricity consumption per ton of product (kWh / t) Antibacterial properties (h) Activation rate (%) Example 2 75.6 139 95.2 Comparative Example 1 112 46 71 Comparative Example 2 109 126 83 Comparative Example 3 82 48 80

[0066] As shown in Table 4, triethanolamine, as a grinding aid monomer, is the main factor affecting grinding efficiency and can significantly improve grinding efficiency (reduce power consumption per ton of product). Comparative Examples 1 and 2 did not add triethanolamine, so their power consumption per ton of product was relatively high. Comparative Example 3 added triethanolamine to the basis of Comparative Example 1, which can significantly improve grinding efficiency, but its power consumption per ton of product is still higher than that of Example 2.

[0067] The antibacterial modifier GPHMG is the main factor affecting antibacterial performance. Comparative Examples 1 and 3 did not add glycidyl methacrylate (GMA) and could not synthesize GPHMG, so the antibacterial performance of the products was poor. Comparative Example 2 added GMA to the product of Comparative Example 1 and was able to synthesize GPHMG, which greatly improved the antibacterial performance of the product, but it was still lower than that of Example 2.

[0068] Grinding aid is the first modification of calcium carbonate, which has a certain coating effect and a certain impact on the activation rate. In Comparative Example 1, without the addition of glycidyl methacrylate (GMA) and triethanolamine, the grinding aid could not form an effective coating on the surface of calcium carbonate, and the activation rate was significantly reduced. Comparative Examples 2 and 3 added glycidyl methacrylate (GMA) and triethanolamine respectively to Comparative Example 1, which could improve the coating effect to a certain extent, thereby increasing the product activation rate. However, this improvement effect was still not as good as the improvement effect when the two were used together.

[0069] In summary, the combined use of GMA and triethanolamine can synergistically improve the grinding efficiency of grinding aids, as well as the antibacterial properties and activation rate of the products.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing calcium carbonate for sanitary materials, characterized in that, Includes the following steps: (1) Synthesis of grinding aid: Polyhexamethylene guanidine hydrochloride (PHMG) and glycidyl methacrylate (GMA) are mixed and reacted under heating conditions to obtain antibacterial modifier GPHMG. The weight ratio of polyhexamethylene guanidine hydrochloride to glycidyl methacrylate is 40-60:40-60. Then, the antibacterial modifier is stirred and emulsified with emulsifier and triethanolamine to obtain grinding aid. The weight ratio of antibacterial modifier to emulsifier is 40-50:50-60. (2) Add the heavy calcium carbonate raw material to a roller mill, add grinding aid and grind to obtain a mixture; (3) The mixture is finely graded to obtain powder with D90 of 7-8 μm and D50 of 3-4 μm. This powder is used as a raw material for heavy calcium carbonate for sanitary materials and is then activated in an activation unit. Stearic acid is used as a surface modifier in the activation treatment. The powder is atomized and sprayed in at a pressure of 0.3-0.7 MPa. The activation temperature is 90-100℃ and the activation time is 3-5 min.

2. The method for preparing calcium carbonate for sanitary materials according to claim 1, characterized in that: In step (1), the temperature is heated to 50-60℃.

3. The method for preparing calcium carbonate for sanitary materials according to claim 1, characterized in that: In step (1), the amount of triethanolamine added is 20-30% of the weight of the grinding aid.

4. The method for preparing calcium carbonate for sanitary materials according to claim 1, characterized in that: In step (2), the roller mill is an ultrafine vertical roller mill with a material layer thickness of 4-5 cm and an internal pressure of 6-7 MPa.

5. The method for preparing calcium carbonate for sanitary materials according to claim 1, characterized in that: In step (2), the amount of grinding aid added is 0.5 to 0.7% of the weight of the heavy calcium carbonate raw material.

6. The method for preparing calcium carbonate for sanitary materials according to claim 1, characterized in that: In step (3), the classifier speed is 2300-2500 r / min.

7. A method for preparing sanitary material-specific calcium carbonate according to any one of claims 1 to 6.

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