High-dispersion carbon black for conductive plastic and preparation method of high-dispersion carbon black

Abstract

The invention discloses high-dispersion carbon black for conductive plastic and a preparation method of the high-dispersion carbon black, the optimal particle distribution state of the high-dispersion carbon black for plastic conduction is as follows in percentage by mass: 19%-21% of 18 meshes, 48%-52% of 35 meshes, 19%-21% of 35 meshes and 6%-14% of 10 meshes. The preparation method has the beneficial effects that the prepared carbon black meets the optimal particle distribution, the carbon black is filled into the plastic, the particle dispersion condition of the plastic and the particle structure related parameters and resistivity after the plastic is filled with the carbon black are detected, it is verified that the carbon black meeting the optimal particle distribution has good dispersity in the plastic, and the conductivity of the plastic is effectively improved. The distribution condition of carbon black particles can be effectively adjusted, high-dispersion carbon black is prepared, and the conductivity of a plastic product can be effectively improved by filling plastic with the high-dispersion carbon black.

Description

Technical Field

[0001] The present invention relates to the field of carbon black, and specifically to a highly dispersed carbon black for conductive plastics and a preparation method thereof. Background Art

[0002] As a conductive filler for plastics, carbon black builds a channel for electron conduction in the originally insulating plastic matrix, which can effectively reduce the surface resistance or volume resistance of plastics, realize the antistatic or conductive function of plastic products, and is used in key fields such as lithium batteries, cable shielding materials, and conductive color masterbatches.

[0003] In the field of conductive carbon black in China, the challenges are severe. Special conductive carbon black used in high-end plastic products mostly relies on imports. Domestic carbon black is mostly used in mid- to low-end products. When used in high-end products, there are problems such as many surface pockmarks, high volume resistivity, insufficient gloss, poor toughness, and poor dilution. International advanced enterprises master the core technology of high-performance conductive carbon black. Their products have good conductivity, cleanliness, and consistency, large specific surface area, developed structure, and can make plastics conduct electricity well with low addition amounts.

[0004] Research shows that the high conductive effect of carbon black on plastics is not only determined by the basic properties unique to carbon black such as the purity, specific surface area, particle size, and structure degree of carbon black, but also the dispersibility is a key factor determining whether carbon black can fully exert its conductive performance in the base material.

[0005] Based on this, the present invention proposes a carbon black for plastic conduction, a method for preparing carbon black with the best particle distribution, so that the carbon black obtains good dispersion performance and is applied to plastics, effectively improving the conductive performance of plastics, and finally realizing the preparation method and application of carbon black for the mid- to high-end plastic industry. Summary of the Invention

[0006] The present invention aims to solve the dispersibility of carbon black, and provides a highly dispersed carbon black for conductive plastics and a preparation method thereof, so that the carbon black meets the best particle distribution, and thus the prepared highly dispersed carbon black is suitable for high-end plastics and provides high conductive performance for them.

[0007] The technical solution adopted by the present invention is as follows: A highly dispersed carbon black for conductive plastics, in the best particle distribution state, by mass fraction, the proportion of 18mesh is 19% - 21%, the proportion of 35mesh is 48% - 52%, the proportion of 35mesh is 19% - 21%, and the proportion of 10mesh is 6% - 14%.

[0008] The present invention adopts another technical solution: A preparation method of a highly dispersed carbon black for conductive plastics, specifically:

[0009] (1) Filter and remove impurities from the compressed air, first heat it to 220°C at a rate of 5 - 10°C / min, and then preheat it to 650°C at a rate of 15 - 20°C / min;

[0010] (2) Feed the preheated compressed air into the reaction furnace at a flow rate of 9.5 - 10.5 km 3 / h, maintain the flow rate ratio of natural gas to the potassium carbonate aqueous solution with a potassium carbonate mass fraction of 1.75% at 5:1, and carry out the combustion reaction at 1880 - 1920 °C;

[0011] (3) Preheat the raw material mixed oil at 80 °C for 4 min to 250 °C, and then add it into the reaction furnace at a flow rate of 2500 kg / h for pyrolysis reaction for 20 μs to produce carbon black flue gas; the raw material mixed oil contains coal tar and carbon black oil, and the sum of their mass percentages accounts for ≥ 65% of the total mass of the raw material mixed oil;

[0012] (4) Quench the carbon black flue gas described in step (3) twice. For the first quench, the pressure of the quench water is 1.0 MPa and the flow rate is 15 m 3 / h to reduce the temperature of the carbon black flue gas to 730 °C. For the second quench, the pressure of the quench water is 1.0 MPa and the flow rate is 12 m 3 / h to reduce the temperature of the carbon black flue gas to 260 °C;

[0013] (5) The cooled carbon black flue gas enters the main bag filter for collection. The collected carbon black is pulverized by a micron pulverizer and then sent to a cyclone separator;

[0014] (6) Adopt wet granulation. Mix the granulation water and carbon black powder at a temperature of 85 °C - 95 °C. Set the frequency of the granulator at 35 Hz - 48 Hz. By controlling the flow rate and pressure of the granulation water, precisely regulate the size of the carbon black granules;

[0015] (7) The flow rate of the granulator is 1400 - 1900 kg / h, the pressure of the granulation water is 0.4 - 0.7 MPa, and the carbon black granules obtained after granulation have a particle size of 0.6 - 1.0 mm;

[0016] (8) Finally, dry at 250 °C, and obtain the carbon black meeting the best particle size distribution through precise process control, the use of advanced equipment, and strict quality inspection procedures.

[0017] Further, the pH is adjusted during the carbon black granulation process with the granulation water, and the granulation water includes at least one of pure water, an aqueous solution of lignin calcium carbonate, an aqueous solution of sodium hydroxide, an aqueous solution of sodium carbonate, or an aqueous solution of phosphoric acid.

[0018] Further, the granulation water includes a binder with a mass concentration of 0 - 13%. The binder plays a binding role during the carbon black granulation process, and the binder includes at least one of lignosulfonate, polyvinyl alcohol, molasses, starch, or dextrin.

[0019] Furthermore, the temperature of the granulation water is 70°C to 80°C. Controlling the temperature of the granulation water can improve the affinity between the granulation water and carbon black, accelerate the wetting rate of the granulation water to the carbon black powder, and improve the granulation effect. By controlling the flow rate and pressure of the granulation water, the size of the carbon black granules can be regulated. When the flow rate and pressure of the granulation water are at a low level, the supply of the granulation water is insufficient during the carbon black granulation process, resulting in poor granulation effect of the carbon black and a relatively small overall particle distribution of the carbon black. On the contrary, if the flow rate and pressure of the granulation water are too high, an excessive amount of granulation water will participate in the carbon black granulation process, not only causing the carbon black granulation particles to be too large, but also prolonging the subsequent drying time, which is not conducive to actual production.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The prepared carbon black meets the optimal particle distribution. After filling it into plastics, the particle dispersion, relevant parameters of the particle structure after carbon black filling in plastics, and resistivity are detected, verifying that the carbon black meeting the optimal particle distribution has good dispersion in plastics and effectively improves the electrical conductivity of plastics.

[0022] (2) By setting the flow rate to 1400 kg / h to 2400 kg / h and the pressure to 0.4 MPa to 0.7 MPa, the particle distribution of carbon black can be effectively adjusted, and highly dispersed carbon black can be prepared. Filling it into plastics can effectively improve the electrical conductivity of plastic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the plate effect diagram of Comparative Example 1, Comparative Example 2 and Example 1. SPECIFIC EMBODIMENTS

[0024] Hereinafter, the concept and technical effects of the present invention will be described to fully understand the purpose and preparation effect of the present invention. In this embodiment, a commercially available carbon black powder with good performance from a well-known domestic brand is selected and mixed with granulation water to make carbon black granulation as a comparative example. Among them, the temperature of the granulation water is 70°C to 80°C, the flow rate of the granulation water is 1400 kg / h to 2400 kg / h, the pressure is 0.4 MPa to 0.7 MPa, and the flow rate of the granulation aid is 0 to 1.3 kg / h. This can improve the affinity between the granulation water and carbon black, accelerate the wetting temperature of the granulation water to the carbon black powder, and improve the granulation effect.

[0025] Production process of the comparative example:

[0026] (1) Prepare a granulation aqueous solution by mixing soft water and lignin according to a mass percentage of 97:3, and at the same time heat the prepared granulation aqueous solution to 77°C by using a heat exchanger;

[0027] (2) Spray the preheated granulation aqueous solution and diesel into the granulator simultaneously to mix with carbon black powder for granulation. The injection pressure of the granulation water is 0.6 MPa, the flow rate is 1900 kg / h, and the flow rate of the granulation aid is 1.3 kg / h. Adjust the frequency of the granulator to 45 Hz, and use the steam heating jacket to raise the temperature of the granulator to 80 °C;

[0028] (3) Use an air blower with a rotational speed frequency of 45 Hz to send the carbon black after granulation to a rotary dryer, adjust the temperature of the dryer to 100 °C, and perform drying treatment on the granulated carbon black to obtain the carbon black granulation, that is, Comparative Example 1.

[0029] Production process of the example:

[0030] (1) Prepare a granulation aqueous solution by mixing soft water and lignin according to a mass percentage of 91:9, and simultaneously heat the prepared granulation aqueous solution to 70 °C using a heat exchanger;

[0031] (2) Spray the preheated granulation aqueous solution and diesel into the granulator simultaneously to mix with carbon black powder for granulation. The injection pressure of the granulation water is 0.4 MPa, the flow rate is 1400 kg / h, and the flow rate of the granulation aid is 0.5 kg / h. Adjust the frequency of the granulator to 45 Hz, and use the steam heating jacket to raise the temperature of the granulator to 75 °C;

[0032] (3) Use an air blower with a rotational speed frequency of 45 Hz to send the carbon black after granulation to a rotary dryer, adjust the temperature of the dryer to 260 °C, and perform drying treatment on the granulated carbon black, that is, Example 1.

[0033] Detect the physical and chemical parameters, particle dispersion, particle structure related parameters, and resistivity after filling plastic PP of the carbon black in Comparative Example 1, Comparative Example 2, and Example 1. The present invention compares the detection results of Comparative Example 1, Comparative Example 2 (carbon black granulation produced by a well-known foreign conductive carbon black factory), and Example 1.

[0034] As shown in Table 1 are the physical and chemical parameters of Comparative Example 1, Comparative Example 2, and Example 1. It can be seen that the iodine absorption value, oil absorption value, coloring strength, and NSA of Comparative Example 1 and Example 1 prepared by different granulation processes are relatively close, while by controlling the flow rate and pressure of the granulation water, the particle distribution of the prepared carbon black is different.

[0035] As shown in Table 2, due to the relatively large flow rate of the granulation water controlled for the carbon black in Comparative Example 1, there are more particles with a smaller mesh number and fewer particles with a larger mesh number in the carbon black of Comparative Example 1, and the overall particle distribution shows an obvious unbalanced trend of thick and thin particles, which is quite different from the best particle distribution form proposed by the present invention and cannot meet the requirements of plastics for the particle distribution of carbon black, while the particle dispersion of Comparative Example 2 and the prepared Example 1 is almost the same as the best particle distribution form.

[0036] Table 1 Physicochemical parameters of Comparative Example 1, Comparative Example 2 and Example 1

[0037]

[0038] Table 2 Particle dispersion of Comparative Example 1, Comparative Example 2 and Example 1

[0039]

[0040]

[0041] In order to detect the dispersion performance of the carbon black with the best particle distribution prepared by the present invention in plastics and its effect on the conductive properties of plastics, this experiment filled Comparative Example 1, Comparative Example 2 and Example 1 into polypropylene (PP) to prepare conductive masterbatch and conductive plastic plate, respectively. The surface states of the three plates were observed, the test parameter results of the particle structure were compared, and the surface resistance of the conductive masterbatch and the volume resistivity of the conductive plastic plate were tested.

[0042] The preparation of conductive masterbatch includes the following steps:

[0043] (1) The carbon black granules of Comparative Example 1, Comparative Example 2 and Example 1 were mixed with PP resin at a ratio of 5% to 20%, and then the mixed carbon black granules and PP resin were added to a high-speed mixer, and antioxidants and lubricants were added to preliminarily mix the two materials. The mixing time was set to 5 to 10 minutes and the speed was set to 1000 to 1500 rpm to ensure that the materials were fully mixed;

[0044] (2) The three mixed materials are respectively placed in a twin-screw extruder, the heating temperature is controlled at 200° C. to 240° C., the screw speed is controlled at 200 to 600 rpm, and the molten materials are extruded into strips through the extruder head, and then cooled and solidified through a cooling water tank, and then cut into particles of a certain size by a pelletizer, thereby obtaining the conductive masterbatch of the carbon black filled plastic.

[0045] The preparation of the conductive plastic sheet includes the following steps:

[0046] (1) adding 1% to 5% of the mass of the conductive masterbatch of polyethylene wax, stearic acid and its salts or a dispersing aid in EVA (ethylene-vinyl acetate copolymer) to the three conductive masterbatch to improve the dispersibility and stability of carbon black in the plastic substrate;

[0047] (2) Using hot pressing equipment, the temperature is controlled at 180°C to 220°C to preheat the mold, and then the three prepared conductive masterbatches are placed in the preheated mold cavity respectively, and vibration feeding is used to assist in spreading the materials so that the materials are evenly distributed in the mold;

[0048] (3) closing the mold and performing hot pressing, controlling the pressure at 10 to 30 MPa, holding the pressure for 5 to 10 minutes, and then naturally cooling the mold to solidify the plastic plate to obtain the conductive plastic plate.

[0049] like Figure 1 Figures a, b, and c are the plate renderings of Comparative Example 1, Comparative Example 2, and Example 1, respectively. Figure a shows that the surface of Comparative Example 1 is rough and there are large particle impurities. The surface condition, particle distribution, and surface flatness of Comparative Example 2 in Figure b are similar to those of RS682. Compared with Comparative Examples 1 and 2, the surface of Example 1 in Figure c has further reduced large particle protrusions, is more evenly dispersed, and is relatively smooth as a whole.

[0050] To further explore the effect of particle distribution on the dispersion performance of carbon black in plastics, as shown in Table 3, the test results of parameters related to the carbon black particle structure are shown. It can be seen that the dispersion of carbon black is Example 1>Comparative Example 2>Comparative Example 1. It can be seen that after the optimal particle distribution, the dispersion of Example 1 is increased to 86.06%, indicating that the carbon black that meets the optimal particle distribution is more evenly distributed in the system, and the agglomeration phenomenon is reduced, which is more conducive to the dispersion performance of carbon black in plastics; the average diameter is Comparative Example 1>Comparative Example 2>Example 1, indicating that the optimal particle distribution reduces large-size particles and the particle size tends to be more uniform, which helps to improve the dispersion stability of carbon black in the material and the compatibility with the matrix; the particle area and the average particle area are both Comparative Example 1>Comparative Example 2>Example 1. Combining these parameters, it is shown that the optimal particle distribution reduces the number and size of carbon black particle agglomerates, so that carbon black exists in a smaller and dispersed state.

[0051] Table 3 Particle structure related parameters of Comparative Example 1, Comparative Example 2 and Example 1

[0052]

[0053] In order to evaluate the conductive properties of carbon black filled plastics, the carbon blacks of Comparative Example 1, Comparative Example 2 and Example 1 were respectively filled into polypropylene (PP), and conductive masterbatches were prepared as samples and their surface resistance was tested (this method is easier to measure in time during the production process), and then sheet samples with uniform thickness, smooth surface and no obvious defects were prepared, and the volume resistivity was measured by the four-probe method. The measurement results are shown in Table 4. The resistivity of Example 1 and Comparative Example 2 and the volume resistivity after they were filled with plastics are roughly the same, and are lower than Comparative Example 1. This shows that the most important factor in improving the conductive properties of plastics is to improve the dispersion of carbon black. Example 1, which meets the optimal particle distribution of carbon black, has better conductive properties. Therefore, the optimal particle distribution carbon black proposed in the present invention is easy to disperse in plastics and makes plastics have better conductive properties.

[0054] By making carbon black meet the theoretical optimal particle distribution, the dispersion performance of carbon black can be significantly improved, thereby further enhancing the electrical conductivity of plastics, narrowing the gap with the physicochemical parameter performance of foreign carbon black, achieving less or even no pitting on the surface and uniform particle distribution, and effectively solving the problems of domestic carbon black in the actual production of high-end conductive plastics.

[0055] Table 4 Resistivity of Example 1, Example 2 and Comparative Example 1

[0056]

[0057] The present invention first applies the best particle-dispersed carbon black to the domestic medium and high-end plastic fields. By proposing a method for preparing carbon black with the best particle distribution and detecting its effect when applied to plastics (PP), the dispersion of carbon black in plastics is improved, thereby enhancing the electrical conductivity of plastics, solving domestic technical problems, and narrowing the difference with foreign conductive carbon black products.

Claims

1. A highly dispersed carbon black for conductive plastics, characterized in that: The best particle distribution state, calculated by mass fraction, is 18mesh accounting for 19% to 21%, 35mesh accounting for 48% to 52%, 35mesh accounting for 19% to 21%, and 10mesh accounting for 6% to 14%.

2. The method for preparing highly dispersed carbon black for conductive plastics according to claim 1, characterized in that: Specifically: (1) Filter and remove impurities from the compressed air, first heat it to 220°C at a rate of 5-10°C / min, and then preheat it to 650°C at a rate of 15-20°C / min; (2) Preheat the compressed air at 9.5 to 10.5 km 3 / h flow rate into the reaction furnace, the flow ratio of natural gas to potassium carbonate aqueous solution with a mass fraction of 1.75% potassium carbonate is maintained at 5:1, and the combustion reaction is carried out at 1880-1920°C; (3) preheating the raw mixed oil at 80° C. to 250° C. for 4 min, and then adding it into the reactor at a flow rate of 2500 kg / h for cracking reaction for 20 μs to generate carbon black flue gas; wherein the raw mixed oil comprises coal tar and carbon black oil, and the sum of their mass percentage accounts for ≥65% of the total mass of the raw mixed oil; (4) The carbon black flue gas in step (3) is quenched twice. For the first quench, the quenching water pressure is 1.0 MPa and the flow rate is 15 m 3 / h, the carbon black flue gas temperature is reduced to 730℃, and the second quenching is performed with a quenching water pressure of 1.0MPa and a flow rate of 12m 3 / h, cooling the carbon black flue gas to 260℃; (5) The cooled carbon black flue gas enters the main bag filter for collection. The collected carbon black is crushed by a micron grinder and then sent to a cyclone separator; (6) using wet granulation, mixing granulation water and carbon black powder at a temperature of 85°C to 95°C, setting the granulator frequency at 35Hz to 48Hz, and controlling the flow rate and pressure of granulation water to precisely control the size of carbon black granules; (7) The flow rate of the granulator is 1400-1900 kg / h, the granulation water pressure is 0.4-0.7 MPa, and the carbon black particles obtained after granulation have a particle size of 0.6-1.0 mm; (8) Finally, the product is dried at 250° C. and the carbon black having the best particle size distribution is obtained through precise process control, advanced equipment and strict quality inspection procedures.

3. The method for preparing highly dispersed carbon black for conductive plastics according to claim 2, characterized in that: In step (6), the granulation water is used to adjust the pH during the carbon black granulation process, and the granulation water includes at least one of pure water, lignin calcium carbonate aqueous solution, sodium hydroxide aqueous solution, sodium carbonate aqueous solution or phosphoric acid aqueous solution.

4. The method for preparing highly dispersed carbon black for conductive plastics according to claim 3, characterized in that: The granulation water includes a binder with a mass concentration of 0 to 13%. The binder plays a bonding role in the carbon black granulation process. The binder includes at least one of lignin sulfonate, polyvinyl alcohol, molasses, starch or dextrin.

5. The method for preparing highly dispersed carbon black for conductive plastics according to claim 4, characterized in that: The temperature of granulation water is 70℃~80℃. Controlling the temperature of granulation water can improve the affinity between granulation water and carbon black and accelerate the wetting speed of granulation water on carbon black powder. The size of carbon black granulation can be regulated by controlling the flow rate and pressure of granulation water.

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