Preparation method and application of ultrafine modified calcium carbonate

Abstract

The present invention relates to the technical field of modified calcium carbonate, particularly to the field of IPC C08K, and more specifically to a method for preparing and applying ultrafine modified calcium carbonate. By selecting a specific modifier and combining it with a preparation method, the present invention controls the amount of added additives to below 1.5 wt%, thereby reducing production costs and achieving optimal cost-performance. Furthermore, the prepared calcium carbonate has low oil absorption, high activation rate, and excellent dispersion properties, making it highly suitable for use as a filler modifier for polypropylene, nylon, and ABS plastics.

Description

Technical Field

[0001] The present invention relates to the technical field of modified calcium carbonate, in particular to the field of IPC C08K, and more specifically to a preparation method and application of ultrafine modified calcium carbonate. Background Art

[0002] Calcium carbonate is inexpensive, widely available, and has stable performance, so it is often used as an inorganic filler in plastics, rubber, coatings, stone slabs, paints, and other fields.

[0003] However, ordinary calcium carbonate has a hydrophilic and oleophobic surface, high specific surface energy, and is prone to agglomeration between particles, resulting in poor compatibility with polymers. Therefore, before using it as a filler, the surface of calcium carbonate must be modified to enhance its compatibility with polymers, improve its dispersibility in polymers, and improve its performance.

[0004] Patent document CN201410003736.4 discloses a silane coupling agent / hydroxystearic acid surface-modified calcium carbonate filler. The modification effect of calcium carbonate is improved by adding a variety of additives. However, adding too many additives will lead to high costs.

[0005] Patent document CN201710641984.5 discloses a method for preparing calcium carbonate for paint with a high activation rate and a low oil absorption value. Although it provides a method for preparing calcium carbonate for paint with a high activation rate and a low oil absorption value, its preparation method is cumbersome and not convenient for large-scale use in factories. Summary of the Invention

[0006] In order to solve the above problems, the first aspect of the present invention provides a method for preparing ultrafine modified calcium carbonate, comprising the following steps:

[0007] S1, grinding the rock;

[0008] S2. Stir the ground rock at high speed until the temperature reaches 70-80°C, and keep stirring for 5-15 minutes;

[0009] S3. Adjust the stirring speed to low speed stirring, add the solid additive, increase the speed again to stir at high speed for 1-5 minutes, add the liquid additive, maintain the high speed stirring for 5-10 minutes, and obtain ultrafine modified calcium carbonate.

[0010] Preferably, the particle size of the ground rock is ≤20 μm.

[0011] The inventors unexpectedly discovered that grinding the rock to a particle size of 20 μm or less reduces the oil absorption rate of the resulting modified calcium carbonate. This is likely because rock with a particle size of 20 μm or less can successfully undergo the subsequent high-temperature mixing and modification process. If the rock particle size is too large, the modification effect will be poor and the equipment used in the subsequent mixing process will be damaged, reducing equipment life and increasing costs. Further grinding the rock to a smaller particle size will not only consume energy and time during the grinding process, but also cause the rock with too small a particle size to agglomerate, affecting its dispersion uniformity during the subsequent modification process.

[0012] Preferably, the rotation speed of the high-speed stirring is 400-600 r / min; more preferably, it is 500 r / min.

[0013] The inventors have discovered that high-speed stirring of ground rock, maintaining the temperature at 70-80°C for 5-15 minutes, can further enhance the activity of the modified calcium carbonate and reduce oil absorption. This is likely due to the frictional heat generated by high-speed stirring, which heats up the surface of the ground rock, allowing the rock's moisture to form water vapor, thereby reducing the rock's moisture content and increasing its dryness, thereby improving the activation and modification effect. Furthermore, stirring only rock of a specific particle size to achieve the desired temperature increases, saving energy.

[0014] Preferably, the rotation speed of the low-speed stirring is 200-350 r / min; more preferably, it is 300 r / min.

[0015] Preferably, the rock includes one or more of calcite, talc, feldspar, marble, dolomite, and quartz; more preferably, it is calcite.

[0016] The source of the calcite is not specifically limited and any commercially available calcite may be used. In some preferred embodiments, the calcite is purchased from Xinfeng Mining in Fengshan County, Guangxi.

[0017] Preferably, the weight ratio of the solid additive to the liquid additive is 1:(1-3); more preferably, it is 2:7.

[0018] Preferably, the solid auxiliary agent includes stearic acid.

[0019] The inventor unexpectedly found that, by reducing stirring speed to low-speed stirring, then adding solid additives, it is possible to ensure that when modifying effect, simple process. This may be due to in traditional modification process, because the auxiliary agents such as stearic acid are solid, then when modified, stearic acid can be first heated and melted to liquid, then passed into reactor, step is relatively loaded down with trivial details, and process and equipment are all required. And the application is by reducing stirring speed, solid additives such as stearic acid etc. can be directly added to reactor and stirred, lower rotating speed can avoid stearic acid particles to fly out because of the water vapor pressure under high speed and high temperature, thus affecting the addition and the modifying effect of auxiliary agent, and return to high-speed stirring after adding solid additives, also can heat up by friction stirring by solid additive melting, so that it can be adsorbed on the rock surface after grinding, and the long-chain alkyl structure at the other end has good compatibility with the polymer materials such as polypropylene, nylon, ABS plastics, thus can be used as filling modifier and be applied to modified plastics.

[0020] Preferably, the liquid additive includes one or more of a phosphate surfactant and a coupling agent; more preferably, it includes a phosphate surfactant and a coupling agent.

[0021] Preferably, the weight ratio of the phosphate surfactant to the coupling agent is 1:(1-5); more preferably, it is 2:5.

[0022] Preferably, the phosphate surfactant includes one or more of fatty alcohol ether phosphate, phenol ether phosphate, lauryl phosphate, and isotridecanol phosphate; more preferably, it is fatty alcohol ether phosphate.

[0023] Preferably, the solid content of the fatty alcohol ether phosphate is ≥90 wt %; further preferably, the solid content of the fatty alcohol ether phosphate is ≥95 wt %.

[0024] In some preferred embodiments, the fatty alcohol ether phosphate is purchased from fatty alcohol ether phosphate MOA-3P produced by Hai'an Petrochemical Plant in Jiangsu Province.

[0025] Preferably, the coupling agent is one or more of a silane coupling agent, an aluminate coupling agent, and a titanate coupling agent; more preferably, it is a silane coupling agent.

[0026] Preferably, the silane coupling agent includes one or more of silane coupling agent KH-560, silane coupling agent KH-550, silane coupling agent KH-570, silane coupling agent KH-580, and silane coupling agent KH-590; more preferably, silane coupling agent KH-550.

[0027] In some preferred embodiments, the silane coupling agent KH-550 is purchased from SiLane™ silane coupling agent KH-550 produced by Nanjing Xuanhao New Material Technology Co., Ltd.

[0028] Preferably, the total weight of the solid additive and the liquid additive is less than 1.5 wt% of the weight of the raw material for preparing modified calcium carbonate.

[0029] The inventors have creatively discovered that controlling the stirring speed and time after adding a liquid additive can improve the modification effect. This is likely because high-speed stirring allows the rock and the additive to fully contact and, through frictional heating, fully modify the rock. However, the stirring time should not be too long, as it can lead to excessively high temperatures and volatilization of the added coupling agent, reducing the modification effect. Too short a stirring time prevents the additive from fully fusing and coating the rock surface, resulting in incomplete modification, affecting the modification effect and, in turn, the activity and oil absorption of the modified calcium carbonate.

[0030] The second aspect of the present invention provides a product prepared by the method for preparing ultrafine modified calcium carbonate.

[0031] The third aspect of the present invention provides the application of the ultrafine modified calcium carbonate, which is used in the fields of automobiles, home appliances, warehousing and transportation plastic parts, papermaking, coating ceramics, modified plastics, etc.

[0032] More preferably, it is used as a filler modifier for polypropylene, nylon, and ABS plastics.

[0033] Beneficial effects:

[0034] 1. The present invention can reduce the oil absorption rate of the modified calcium carbonate obtained by grinding the rock to a particle size of ≤20 μm.

[0035] 2. The present invention can further improve the activity of the modified calcium carbonate and reduce the oil absorption rate by stirring the ground rock at high speed and maintaining the temperature at 70-80°C for 5-15 minutes.

[0036] 3. The present invention reduces the stirring speed to low speed stirring and then adds solid additives, which can simplify the process while ensuring the modification effect.

[0037] 4. After adding the liquid additive, the present invention controls the stirring speed and stirring time to improve the modification effect.

[0038] 5. The present invention controls the amount of added additives to below 1.5 wt% by selecting a specific modifier and coordinating the preparation method, thereby reducing production costs and achieving optimal cost-performance. The prepared calcium carbonate has low oil absorption, high activation rate, and good dispersion effect, making it very suitable for use as a filling modifier for polypropylene, nylon, and ABS plastics. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the particle size distribution diagram of the ultrafine modified calcium carbonate prepared in Example 1;

[0040] Figure 2 This is a picture of the ultrafine modified calcium carbonate prepared in Example 1. DETAILED DESCRIPTION

[0041] Example

[0042] Example 1

[0043] Example 1 provides an ultrafine modified calcium carbonate, such as Figure 2 As shown, the preparation method thereof comprises the following steps:

[0044] S1, grinding the rock;

[0045] S2. Stir the ground rock at high speed until the temperature reaches 70°C and keep stirring for 10 minutes;

[0046] S3. Adjust the stirring speed to low speed stirring, add the solid additive, increase the speed again and stir at high speed for 3 minutes, add the liquid additive, maintain the high speed stirring for 7 minutes, and obtain ultrafine modified calcium carbonate.

[0047] The particle size of the ground rock is ≤20 μm.

[0048] The rotation speed of the high-speed stirring is 500 r / min.

[0049] The rotation speed of the low-speed stirring is 300 r / min.

[0050] The rock is calcite.

[0051] The calcite was purchased from Xinfeng Mining in Fengshan County, Guangxi.

[0052] The weight ratio of the solid additive to the liquid additive is 2:7.

[0053] The solid auxiliary agent is stearic acid.

[0054] The liquid auxiliary agents are phosphate surfactants and coupling agents.

[0055] The weight ratio of the phosphate surfactant to the coupling agent is 2:5.

[0056] The phosphate surfactant is fatty alcohol ether phosphate.

[0057] The solid content of the fatty alcohol ether phosphate is ≥95 wt %.

[0058] The fatty alcohol ether phosphate was purchased from fatty alcohol ether phosphate MOA-3P produced by Hai'an Petrochemical Plant in Jiangsu Province.

[0059] The coupling agent is a silane coupling agent.

[0060] The silane coupling agent is silane coupling agent KH-550.

[0061] The silane coupling agent KH-550 was purchased from SiLaneTM silane coupling agent KH-550 produced by Nanjing Xuanhao New Material Technology Co., Ltd.

[0062] The total weight of the solid additive and the liquid additive is 1.5 wt % of the weight of the raw material for preparing modified calcium carbonate.

[0063] Example 2

[0064] Example 2 provides an ultrafine modified calcium carbonate, and the specific implementation method is the same as that of Example 1. The difference is that:

[0065] S2. Stir the ground rock at high speed until the temperature reaches 70°C and keep stirring for 5 minutes;

[0066] S3. Adjust the stirring speed to low speed stirring, add the solid additive, increase the speed again and stir at high speed for 1 minute, add the liquid additive, maintain the high speed stirring for 5 minutes, and obtain ultrafine modified calcium carbonate.

[0067] The rotation speed of the high-speed stirring is 400 r / min.

[0068] The rotation speed of the low-speed stirring is 200 r / min.

[0069] The weight ratio of the solid additive to the liquid additive is 1:1.

[0070] The weight ratio of the phosphate surfactant to the coupling agent is 1:1.

[0071] The total weight of the solid additive and the liquid additive is 1.0 wt% of the weight of the raw material for preparing modified calcium carbonate.

[0072] Example 3

[0073] Example 3 provides an ultrafine modified calcium carbonate, and the specific implementation method is the same as that of Example 1. The difference is that:

[0074] S2. Stir the ground rock at high speed until the temperature reaches 80°C and keep stirring for 15 minutes;

[0075] S3. Adjust the stirring speed to low speed stirring, add the solid additive, increase the speed again and stir at high speed for 5 minutes, add the liquid additive, maintain the high speed stirring for 10 minutes, and obtain ultrafine modified calcium carbonate.

[0076] The rotation speed of the high-speed stirring is 600 r / min.

[0077] The rotation speed of the low-speed stirring is 350 r / min.

[0078] The weight ratio of the solid additive to the liquid additive is 1:3.

[0079] The weight ratio of the phosphate surfactant to the coupling agent is 1:5.

[0080] The total weight of the solid additive and the liquid additive is 1.0 wt% of the weight of the raw material for preparing modified calcium carbonate.

[0081] Comparative Example 1

[0082] Comparative Example 1 provides an ultrafine modified calcium carbonate, and the specific implementation method is the same as Example 1. The difference is:

[0083] The particle size of the ground rock is ≤10 μm.

[0084] Comparative Example 2

[0085] Comparative Example 2 provides an ultrafine modified calcium carbonate, and the specific implementation method is the same as Example 1. The difference is:

[0086] S1, grinding the rock;

[0087] S2. Add the ground rock to the solid additive, stir at high speed for 1-5 minutes, then add the liquid additive, and stir at high speed for 5-10 minutes to obtain ultrafine modified calcium carbonate.

[0088] Comparative Example 3

[0089] Comparative Example 3 provides an ultrafine modified calcium carbonate, and the specific implementation method is the same as Example 1. The difference is:

[0090] S1, grinding the rock;

[0091] S2. Stir the ground rock at high speed until the temperature reaches 70-80°C, and keep stirring for 5-15 minutes;

[0092] S3. Add a solid additive to the product obtained in step S2 and stir at high speed for 1-5 minutes, then add a liquid additive and stir at high speed for 5-10 minutes to obtain ultrafine modified calcium carbonate.

[0093] Comparative Example 4

[0094] Comparative Example 4 provides an ultrafine modified calcium carbonate, and the specific implementation method is the same as Example 1. The difference is:

[0095] S3. Adjust the stirring speed to low speed stirring, add the solid additive, increase the speed again and stir at high speed for 3 minutes, add the liquid additive, maintain the high speed stirring for 15 minutes, and obtain ultrafine modified calcium carbonate.

[0096] Performance Testing

[0097] 1. Activation rate test

[0098] The ultrafine modified calcium carbonate prepared in Examples 1-3 and Comparative Examples 1-4 was subjected to an activation rate test. The test method is as follows:

[0099] Weigh about 5g of sample, accurate to 0.01g, place it in a 250ml separatory funnel, add 200ml of water, shake back and forth at a speed of 120 times / min for 1min, place it gently on the funnel stand, let it stand for 1min, put the sinking sample into the beaker, then transfer the sample in the beaker back to the separatory funnel, rinse the beaker with a small amount of water, and let it stand for 30min. After obvious stratification, filter and wash the sinking sample with dried quantitative filter paper at once, move it to a constant temperature drying oven, dry it at 105±5℃ for half an hour, and then weigh it. The activation degree expressed in mass percentage is X5 according to the formula Calculate, where: m1 is the mass of the precipitate after drying, g; m is the mass of the sample, g. The results are recorded in Table 1.

[0100] 2. Oil absorption test

[0101] The ultrafine modified calcium carbonate prepared in Examples 1-3 and Comparative Examples 1-4 were tested according to the method described in GB / T 19281-2003, and the results are recorded in Table 1.

[0102] 3. Dispersion test

[0103] The particle size distribution of the ultrafine modified calcium carbonate prepared in Example 1 was measured using a laser particle size analyzer. The results are as follows: Figure 1 As shown, from Figure 1 The results show that the prepared ultrafine modified calcium carbonate has small and uniform particle size and good dispersibility.

[0104] Table 1

[0105] pilot projects Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Activation rate% 98.9 98.1 98.2 93.5 95.3 90.2 91.3 Oil absorption ml / 100g 12.5 12.9 13.0 15.8 15.3 16.8 16.2

Claims

1. A method for preparing ultrafine modified calcium carbonate, characterized in that: The preparation method comprises the following steps: S1, grinding the rock; S2. Stir the ground rock at high speed until the temperature reaches 70°C and keep stirring for 10 minutes; S3, adjusting the stirring speed to low speed stirring, adding the solid additive, increasing the speed again to stir at high speed for 3 minutes, adding the liquid additive, maintaining the high speed stirring for 7 minutes, and obtaining ultrafine modified calcium carbonate; The particle size of the ground rock is ≤20 μm; The rotation speed of the high-speed stirring is 500r / min; The rotation speed of the low-speed stirring is 300 r / min; The rock is calcite; The weight ratio of the solid additive to the liquid additive is 2:7; The solid auxiliary agent is stearic acid; The liquid additives are phosphate surfactants and coupling agents; The weight ratio of the phosphate surfactant to the coupling agent is 2:5; The phosphate surfactant is fatty alcohol ether phosphate; The solid content of the fatty alcohol ether phosphate is ≥95wt%; The coupling agent is a silane coupling agent; The silane coupling agent is silane coupling agent KH-550; The total weight of the solid additive and the liquid additive is 1.5 wt % of the weight of the raw material for preparing modified calcium carbonate.

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