Conductive master batch and preparation method thereof

Abstract

The invention discloses a conductive master batch and a preparation method thereof, and belongs to the technical field of conductive master batches. The conductive master batch is prepared from the following raw materials in percentage by mass: 48%-82.25% of polyamide, 1%-5% of micron-sized organic silicon microspheres, 15.5%-40% of conductive filler and 1.25%-7% of auxiliaries, the conductive filler is conductive carbon black. A composite material which is similar to a sea island structure (called a heterogeneous sea island structure) is constructed by taking polyamide as a continuous phase and micron-sized organic silicon microspheres as a dispersed phase. The conductive master batch can ensure effective lap joint between conductive filler particles under the condition of relatively low filling amount of the conductive filler, so that a conductive path is formed. Moreover, the organic silicon microspheres and the aggregated conductive filler particles can generate friction and extrusion in the mixing process, so that the conductive filler particles are reduced, and the conductive filler particles can be uniformly dispersed in a polyamide matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive masterbatch, and in particular to a conductive masterbatch and a preparation method thereof. Background Art

[0002] Conductive masterbatch is a specialized material typically composed of a matrix material and a conductive filler. Among the various conductive fillers, conductive carbon black is the most widely used. Conductive carbon black is highly sought after due to its low cost and readily available supply. Its unique spherical structure allows for easy dispersion within the matrix material and effectively creates a conductive network.

[0003] However, because carbon black has lower electrical conductivity than other conductive materials, a higher proportion of carbon black is usually required to achieve the desired conductive effect. This high addition not only increases costs but may also affect other material properties.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The object of the present invention is to provide a conductive masterbatch and a preparation method thereof, so as to solve or improve the above technical problems.

[0006] The present invention can be achieved like this:

[0007] In a first aspect, the present invention provides a conductive masterbatch, wherein the raw materials for preparing the conductive masterbatch include, by mass percentage, 48% to 82.25% of polyamide, 1% to 5% of micron-sized organic silicon microspheres, 15.5% to 40% of conductive filler, and 1.25% to 7% of additives;

[0008] Wherein, the conductive filler is conductive carbon black.

[0009] In an optional embodiment, the preparation raw materials include 60% to 82% of polyamide, 1% to 5% of micron-sized organic silicon microspheres, 15.5% to 30% of conductive filler and 1.5% to 5% of auxiliary agent.

[0010] In an optional embodiment, the particle size of the conductive carbon black is 20 nm to 30 nm, and the nitrogen attachment specific surface area of the conductive carbon black is 120 m 2 / g~1000m 2 / g, the DBP absorption of conductive carbon black is 120cm 3 / 100g~500cm 3 / 100g, the pH value of conductive carbon black is 6-9.

[0011] In an optional embodiment, the particle size of the micron-sized organosilicon microspheres does not exceed 5 μm.

[0012] In an optional embodiment, the adjuvant includes 0.5% to 3% of a lubricant, 0.25% to 2% of an antioxidant, and 0.5% to 2% of a dispersant.

[0013] In an optional embodiment, the lubricant includes at least one of stearic acid, calcium stearate, magnesium stearate, zinc stearate, paraffin wax, Fischer-Tropsch wax, EVA wax, OP wax, polyethylene wax, Honeywell wax, white oil, chlorinated polyethylene wax, S wax, D wax, DP wax, L wax, oleamide, N,N "-methylene bis stearamide, N,N "-ethylene bis stearamide and metal soap;

[0014] and / or the antioxidant comprises at least one of antioxidant 1076, antioxidant 1010, antioxidant 168, antioxidant 1098, antioxidant 264, antioxidant 2246, antioxidant 330, antioxidant 300, antioxidant 505, antioxidant CA, antioxidant STA-1, antioxidant WPS, antioxidant DLTDP, antioxidant DSTDP, antioxidant ODP, antioxidant TNP, antioxidant A, antioxidant D, antioxidant 228, antioxidant NBC, and antioxidant DNP;

[0015] And / or, the dispersant includes at least one of BYK DISPERBYK-161, Hepfer DS-165A and Clariant DISPERSOGEN-2774.

[0016] In a second aspect, the present invention provides a method for preparing a conductive masterbatch according to any one of the aforementioned embodiments, comprising the following steps: mixing the raw materials for preparation and then extruding and granulating the mixture.

[0017] In an optional embodiment, the mixing includes: first mixing the polyamide with the additive, then adding the silicone microspheres and continuing to mix, and finally mixing with the conductive filler.

[0018] In an optional embodiment, the extrusion granulation comprises: first extruding in a twin-screw extruder, and then pelletizing;

[0019] Among them, the temperature of the first zone of the twin-screw extruder is 220℃~240℃, the temperature of the second to sixth zones is 230℃~250℃, the temperature of the die head is 240℃~260℃, the main engine speed is 180rpm~220rpm, and the feeding speed is 4Hz~8Hz;

[0020] The pelletizing speed is 6Hz to 20Hz.

[0021] The beneficial effects of the present invention include:

[0022] The present invention constructs a composite material similar to a sea-island structure (referred to as a "heterogeneous sea-island structure") by combining a specific content of polyamide as the continuous phase, a specific content of micron-sized organosilicon microspheres as the dispersed phase, and a specific content of conductive filler as the filler. This composite material (conductive masterbatch) ensures effective bonding between the conductive filler particles, forming a conductive pathway, even at relatively low conductive filler loadings. Furthermore, friction and compression between the organosilicon microspheres and the aggregated conductive filler particles during mixing reduce the size of the conductive filler particles, further facilitating their uniform dispersion within the polyamide matrix. The resulting conductive masterbatch exhibits high mechanical strength and electrical conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a comparison chart of surface resistance values of Examples 1 to 8 and Comparative Examples 1 to 2 in the test examples of the present invention;

[0025] Figure 2 This is a comparison chart of the tensile strength of Examples 1 to 8 and Comparative Examples 1 to 2 in the test examples of the present invention;

[0026] Figure 3 This is a comparison chart of the melt indexes of Examples 1 to 8 and Comparative Examples 1 to 2 in the test examples of the present invention;

[0027] Figure 4 Schematic diagram of the effect of silicone microspheres on the distribution of carbon black in polyamide in the test example of the present invention. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0029] The conductive masterbatch and its preparation method provided by the present invention are described in detail below.

[0030] The present invention provides a conductive masterbatch. The raw materials for preparing the conductive masterbatch include, by mass percentage, 48% to 82.25% of polyamide, 1% to 5% of micron-sized organic silicon microspheres, 15.5% to 40% of conductive filler, and 1.25% to 7% of auxiliary agent.

[0031] Wherein, the conductive filler is conductive carbon black.

[0032] In some optional embodiments, the polyamide content can be 48%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or 82.25%, or other values within the range of 48% to 82.25%. In some more typical embodiments, the polyamide content is 60% to 82%, and further, the polyamide content can be 63% to 82%, such as 63%, 67%, 68%, 72%, 73%, 75.5%, 77%, 78%, 79.5% or 82%.

[0033] The above-mentioned polyamide is used as the continuous phase matrix. If the amount of polyamide used is too little, the mechanical properties of the material will be poor; if the amount of polyamide used is too much, the carbon black will be completely coated, and the carbon black particles will not be able to effectively overlap, making it difficult to form a conductive path.

[0034] The content of micron-sized organosilicon microspheres can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., or other values within the range of 1% to 5%.

[0035] The above-mentioned micron-sized silicone microspheres are used as the dispersed phase. If the amount of micron-sized silicone microspheres is too small, the density of the "island" structure will be reduced, thereby weakening the compression effect on the dispersion space of the conductive carbon black, making it impossible for the carbon black particles to effectively overlap with each other, thereby hindering the formation of a conductive path; if the amount of micron-sized silicone microspheres is too large, the sliding internal resistance of the macromolecular chain will be greatly reduced, and the mechanical properties of the material will deteriorate.

[0036] The content of the conductive filler can be 15.5%, 20%, 25%, 30%, 35%, or 40%, or other values within the range of 15.5% to 40%. In some typical embodiments, the content of the conductive filler is 15.5% to 30%. Furthermore, the content of the conductive filler can be 17.5% to 30%, such as 17.5%, 20%, 25%, or 30%.

[0037] The above-mentioned conductive filler is used as a filling material. If the amount of the conductive filler is too small, it is not conducive to forming a conductive path; if the amount of the conductive filler is too large, the viscosity of the system increases and the processing is difficult.

[0038] The content of the additive can be 1.25%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5% or 7%, etc., or other values within the range of 1.25% to 7%. In some typical embodiments, the content of the additive is 1.5% to 5%.

[0039] In some preferred embodiments, the raw materials for preparing the conductive filler include 60% to 82% polyamide, 1% to 5% micron-sized silicone microspheres, 15.5% to 30% conductive filler, and 1.5% to 5% additives.

[0040] In the present invention, the particle size of the conductive carbon black is 20nm to 30nm, and the nitrogen adhesion specific surface area of the conductive carbon black is 120m 2 / g~1000m 2 / g, the DBP absorption of conductive carbon black is 120cm 3 / 100g~500cm 3 / 100g, the pH value of conductive carbon black is 6-9.

[0041] In the present invention, the polyamide is preferably in powder form, which can be more evenly mixed with the conductive filler than polyamide in granular form, thereby avoiding an uneven state in which the granular material is deposited at the bottom and the powder material is distributed at the top in the mixture.

[0042] The particle size of the micron-sized organosilicon microspheres does not exceed 5 μm, and is preferably 0.5 μm to 2 μm. If the particle size of the micron-sized organosilicon microspheres is too large, uneven dispersion may occur, which may reduce the effect of forming a conductive path.

[0043] In some optional embodiments, the adjuvant may include 0.5% to 3% of a lubricant, 0.25% to 2% of an antioxidant, and 0.5% to 2% of a dispersant.

[0044] The amount of lubricant used may be 0.5%, 1%, 1.5%, 2%, 2.5% or 3%, etc., or other values within the range of 0.5% to 3%.

[0045] The dosage of the antioxidant may be 0.25%, 0.5%, 1%, 1.5% or 2%, etc., or other values within the range of 0.25% to 2%.

[0046] The amount of the dispersant used can be 0.5%, 1%, 1.5% or 2%, etc., or other values within the range of 0.5% to 2%.

[0047] In some preferred embodiments, the raw materials for preparing the conductive filler include 60% to 82% polyamide, 1% to 5% micron-sized silicone microspheres, 15.5% to 30% conductive filler, 1% lubricant, 0.5% antioxidant and 0.5% dispersant.

[0048] In some optional embodiments, the lubricant may illustratively but not limitatively include at least one of stearic acid, calcium stearate, magnesium stearate, zinc stearate, paraffin wax, Fischer-Tropsch wax, EVA wax, OP wax, polyethylene wax, Honeywell wax, white oil, chlorinated polyethylene wax, S wax, D wax, DP wax, L wax, oleamide, N,N "-methylene bis stearamide, N,N "-ethylene bis stearamide and metal soap;

[0049] The antioxidant may illustratively but not limitatively include at least one of antioxidant 1076, antioxidant 1010, antioxidant 168, antioxidant 1098, antioxidant 264, antioxidant 2246, antioxidant 330, antioxidant 300, antioxidant 505, antioxidant CA, antioxidant STA-1, antioxidant WPS, antioxidant DLTDP, antioxidant DSTDP, antioxidant ODP, antioxidant TNP, antioxidant A, antioxidant D, antioxidant 228, antioxidant NBC and antioxidant DNP.

[0050] The dispersant may illustratively but not limitatively include at least one of DISPERBYK-161, Hepfer DS-165A, and DISPERSOGEN-2774.

[0051] Continuing from the above, the present invention constructs a composite material similar to a sea-island structure (referred to as a "heterogeneous sea-island structure") by using a specific content of polyamide as the continuous phase, a specific content of micron-sized organosilicon microspheres as the dispersed phase, and a specific content of conductive filler as the filler material. This composite material (conductive masterbatch) ensures effective bonding between the conductive filler particles, forming a conductive pathway, even at relatively low conductive filler loadings. Furthermore, the aforementioned organosilicon microspheres and aggregated conductive filler particles can generate friction and compression during mixing, reducing the size of the conductive filler particles and facilitating their uniform dispersion within the polyamide matrix. The resulting conductive masterbatch exhibits high mechanical strength and electrical conductivity.

[0052] Accordingly, the present invention provides a method for preparing the conductive masterbatch, comprising the following steps: mixing the raw materials and then extruding and granulating them.

[0053] In some typical embodiments, the mixing includes: first mixing the polyamide with the additive, then adding the silicone microspheres and continuing to mix, and finally mixing with the conductive filler.

[0054] The above method can evenly disperse the auxiliary agent in the polyamide matrix first, so that the auxiliary agent can play its role when mixed with the conductive filler and achieve even mixing and distribution among the materials.

[0055] In some optional embodiments, extrusion granulation includes: first extruding in a twin-screw extruder, and then pelletizing;

[0056] Among them, the temperature of zone one of the twin-screw extruder is 220°C to 240°C (such as 220°C, 230°C or 240°C, etc.), the temperature of zones two to six is 230°C to 250°C (such as 230°C, 240°C or 250°C, etc.), the temperature of the die head is 240°C to 260°C (such as 240°C, 250°C or 260°C, etc.), the main engine speed is 180rpm to 220rpm (such as 180rpm, 200rpm or 220rpm, etc.), the feeding speed is 4Hz to 8Hz (such as 4Hz, 6Hz or 8Hz, etc.), and the pelletizing speed can be 6Hz to 20Hz (such as 6Hz, 8Hz, 10Hz, 12Hz, 14Hz, 16Hz, 18Hz or 20Hz, etc.).

[0057] By extruding and granulating under these conditions, friction and compression occur between the silicone microspheres and the aggregated conductive filler particles during the preparation process, reducing the size of the conductive filler particles and facilitating their uniform dispersion within the polyamide matrix. The resulting conductive masterbatch exhibits high mechanical strength and electrical conductivity.

[0058] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0059] Example 1

[0060] This embodiment provides a conductive masterbatch, the preparation method of which includes:

[0061] S1: 755 g of polyamide (PA6) powder, 10 g of lubricant (polyethylene wax), 5 g of antioxidant (1098), and 5 g of dispersant (Hepfer DS-165A) were mixed in a high-speed mixer to obtain a first mixture;

[0062] S2: adding 50 g of organosilicon microspheres having a particle size of 1 μm to the first mixture and continuing to mix to obtain a second mixture;

[0063] S3: adding 175 g of conductive carbon black to the second mixture and continuing to mix uniformly to obtain a third mixture;

[0064] Among them, the particle size of conductive carbon black is 20nm~25nm, and the nitrogen adhesion specific surface area is 150m 2 / g~250m 2 / g, DBP absorption is 130cm3 / 100g~180cm 3 / 100g, pH value is 6-7.

[0065] S4: The third mixture is introduced into a co-rotating twin-screw extruder for extrusion and pelletization. The temperature of zone 1 of the twin-screw extruder is 230°C, the temperature of zones 2 to 6 is 240°C, the die head temperature is 250°C, the main engine speed is 200 rpm, the feeding rate is 6 Hz, and the pelletizing rate is 18 Hz.

[0066] Example 2

[0067] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 795g polyamide powder, 175g conductive carbon black, 10g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0068] Example 3

[0069] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 730 g polyamide powder, 200 g conductive carbon black, 50 g silicone microspheres, 10 g lubricant, 5 g antioxidant and 5 g dispersant.

[0070] Example 4

[0071] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 770g polyamide powder, 200g conductive carbon black, 10g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0072] Example 5

[0073] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 680g polyamide powder, 250g conductive carbon black, 50g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0074] In addition, the pelletizing speed was 14 Hz.

[0075] Example 6

[0076] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 720 g polyamide powder, 250 g conductive carbon black, 10 g silicone microspheres, 10 g lubricant, 5 g antioxidant and 5 g dispersant.

[0077] In addition, the pelletizing speed was 14 Hz.

[0078] Example 7

[0079] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 630 g polyamide powder, 300 g conductive carbon black, 50 g silicone microspheres, 10 g lubricant, 5 g antioxidant and 5 g dispersant.

[0080] In addition, the pelletizing speed was 10 Hz.

[0081] Example 8

[0082] The difference between this embodiment and embodiment 1 is that the amounts of the raw materials used in the preparation are different, specifically: 670g polyamide powder, 300g conductive carbon black, 10g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0083] In addition, the pelletizing speed was 10 Hz.

[0084] Example 9

[0085] This embodiment provides a conductive masterbatch, the preparation method of which includes:

[0086] S1: 480 g of polyamide (PA6) powder, 30 g of lubricant (zinc stearate), 20 g of antioxidant (1076), and 20 g of dispersant (Clariant DISPERSOGEN-2774) were mixed in a high-speed mixer to obtain a first mixture;

[0087] S2: adding 50 g of organosilicon microspheres having a particle size of 0.5 μm to the first mixture and continuing to mix to obtain a second mixture;

[0088] S3: Add 400 g of conductive carbon black to the second mixture and continue mixing to obtain a third mixture;

[0089] Among them, the particle size of conductive carbon black is 20nm~25nm, and the nitrogen adhesion specific surface area is 130m 2 / g, DBP absorption is 145cm 3 / 100g~155cm 3 / 100g, pH value is 8.0.

[0090] S4: The third mixture is introduced into a co-rotating twin-screw extruder for extrusion pelletization. The temperature of zone 1 of the twin-screw extruder is 220°C, the temperature of zones 2 to 6 is 230°C, the die head temperature is 240°C, the main engine speed is 150 rpm, the feeding rate is 4 Hz, and the pelletizing rate is 8 Hz.

[0091] Example 10

[0092] This embodiment provides a conductive masterbatch, the preparation method of which includes:

[0093] S1: 817.5 g of polyamide (PA6) powder, 5 g of lubricant (zinc stearate), 2.5 g of antioxidant (1076), and 5 g of dispersant (Clariant DISPERSOGEN-2774) were mixed in a high-speed mixer to obtain a first mixture;

[0094] S2: adding 10 g of organosilicon microspheres having a particle size of 2 μm to the first mixture and continuing to mix to obtain a second mixture;

[0095] S3: adding 160 g of conductive carbon black to the second mixture and continuing to mix uniformly to obtain a third mixture;

[0096] Among them, the particle size of conductive carbon black is 20nm~25nm, and the nitrogen adhesion specific surface area is 850m 2 / g~1000m 2 / g, DBP absorption is 400cm 3 / 100g~450cm 3 / 100g, pH value is 6.5~9.0.

[0097] S4: The third mixture is introduced into a co-rotating twin-screw extruder for extrusion pelletization. The temperature of zone 1 of the twin-screw extruder is 240°C, the temperature of zones 2 to 6 is 250°C, the die head temperature is 260°C, the main engine speed is 250 rpm, the feeding speed is 8 Hz, and the pelletizing speed is 6 Hz.

[0098] Comparative Example 1

[0099] The difference between this comparative example and Example 1 is that the amounts of the raw materials used in the preparation are different, specifically: 780g polyamide powder, 150g conductive carbon black, 50g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that the amounts of the raw materials used in the preparation are different, specifically: 820g polyamide powder, 150g conductive carbon black, 10g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0102] Comparative Example 3

[0103] The difference between this comparative example and Example 1 is that the amounts of the raw materials used in the preparation are different, specifically: 755g polyamide powder, 165g conductive carbon black, 60g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0104] Comparative Example 4

[0105] The difference between this comparative example and Example 1 is that the amounts of the raw materials used in the preparation are different, specifically: 795g polyamide powder, 180g conductive carbon black, 5g silicone microspheres, 10g lubricant, 5g antioxidant and 5g dispersant.

[0106] Comparative Example 5

[0107] The difference between this comparative example and Example 1 is that the amounts of the raw materials used in the preparation are different, specifically: 460g polyamide powder, 420g conductive carbon black, 50g silicone microspheres, 30g lubricant, 20g antioxidant and 20g dispersant.

[0108] Comparative Example 6

[0109] The difference between this comparative example and Example 1 is that the particle size of the micron-sized organic silicon microspheres is 10 μm.

[0110] Comparative Example 7

[0111] The difference between this comparative example and Example 1 is that the polyamide is in the form of particles.

[0112] Comparative Example 8

[0113] The difference between this comparative example and Example 1 is that all the preparation raw materials are mixed at the same time.

[0114] Comparative Example 9

[0115] The difference between this comparative example and Example 1 is that it does not contain silicone microspheres.

[0116] Test example

[0117] ①. Surface resistance test:

[0118] The conductive masterbatch prepared in Examples 1 to 10 and Comparative Examples 1 to 9 was pressed into sheets with a thickness of 0.5 cm using a flat vulcanizer. The surface resistance of each sheet was accurately measured using a surface resistance meter (test area: 10 cm × 10 cm). The results are shown in Table 1 and Figure 1 shown. Figure 1 The results of the surface resistance values of Examples 1 to 8 and Comparative Examples 1 to 2 are shown.

[0119] ②, Tensile strength test:

[0120] The conductive masterbatch prepared in Examples 1 to 10 and Comparative Examples 1 to 9 was respectively used to make tensile bars with a size of 150 mm × 10 mm × 4 mm by an injection molding machine. The tensile strength was measured using a universal tensile machine in accordance with GB / T 1040.1-2018 standard. The results are shown in Table 1 and Figure 2 shown. Figure 2 The results of tensile strength correspond to Examples 1 to 8 and Comparative Examples 1 to 2.

[0121] ③ Melt index test: The conductive masterbatch prepared in Examples 1 to 10 and Comparative Examples 1 to 9 was tested according to ISO 1133 standard, with the measurement temperature at 250°C and the load at 2.16 kg. The results are shown in Table 1 and Figure 3 shown. Figure 3 The melt index results correspond to Examples 1 to 8 and Comparative Examples 1 to 2.

[0122] Table 1 Surface resistance, tensile strength and melt index of conductive masterbatch at different ratios

[0123]

[0124] According to Table 1 and Figure 1 It can be seen from the results that when the content of carbon black in the entire raw material is ≤15% (refer to comparative examples 1 to 2), the organosilicon microspheres cannot play their expected role in promoting the improvement of conductive properties. The reason may be that when the carbon black content is low, the carbon black particles are more dispersed and it is difficult to form an effective conductive network. In this case, the organosilicon microspheres not only cannot help carbon black reduce the surface resistance of the material, but may also inhibit the construction of the conductive path to a certain extent. However, as the carbon black content increases, the spacing between the carbon black particles gradually decreases. The addition of organosilicon microspheres further reduces the spacing between the carbon black particles, thereby making the conductive network more compact, thereby causing a decrease in surface resistance.

[0125] In addition, if the amount of organosilicon microspheres added is too low, the effect of improving the conductive properties will not be significant (see Example 1 and Comparative Example 4), and the effect of too low an addition on the dispersion of carbon black is not good. Organosilicon microspheres can effectively promote the sliding of molecular chains and reduce the secondary force between carbon black particles in the system by virtue of the shape characteristics of their particles, making it difficult for carbon black particles to agglomerate. If carbon black exists in the form of particles with larger particle size in the nylon matrix, stress concentration will occur in the material and the mechanical properties will deteriorate. On the contrary, if the amount of organosilicon microspheres added is too high, it will have a significant negative impact on other properties of the material (see Example 1 and Comparative Example 3), excessive lubrication between carbon black and nylon, reduced strength of nylon, and no way to get good dispersion of carbon black. Therefore, the control of the amount of addition is the key to realizing the application of organosilicon microspheres in conductive materials. In the present invention, by precisely controlling the amount of organosilicon microspheres added, it is possible to ensure that a conductive network is effectively constructed without sacrificing other properties of the material. Experimental results show that when the addition amount of silicone microspheres is within a specific range, the conductive properties of the material can be significantly improved, while maintaining the mechanical strength of the material without large fluctuations with the increase of carbon black content.

[0126] Furthermore, in order to study the effect of organosilicon microspheres on the distribution of carbon black in polyamide, a control group was set up taking Example 1 as an example. The difference between Comparative Example 9 and Example 1 is that organosilicon microspheres were not added to the raw materials for preparation. Figure 4 , Figure 4 Figure (a) shows the distribution of carbon black in polyamide without the addition of silicone microspheres. The results show that although the carbon black particles can form a certain number of conductive paths in the matrix, the particles are relatively dispersed and it is difficult to form a relatively complete conductive path. Figure 4 (b) shows the distribution of carbon black in polyamide after adding silicone microspheres. The results show that under the condition of equal carbon black filling, after introducing a specific amount of silicone microspheres, the dispersion space of carbon black is reduced and the particle spacing is reduced, which is more conducive to building a complete and effective conductive path.

[0127] By comparing Example 1 with Comparative Examples 5 to 8, it can be seen that improper polyamide dosage and raw material form, improper particle size of silicone microspheres, or improper preparation method will affect the conductive properties and mechanical properties of the material.

[0128] In summary, the present invention constructs a composite material (conductive masterbatch) with a sea-island structure (referred to as a "heterogeneous sea-island structure") by using polyamide as the continuous phase and micron-sized organosilicon microspheres as the dispersed phase. This conductive masterbatch ensures effective bonding between the conductive filler particles, forming a conductive pathway, even at relatively low conductive filler loadings. This conductive masterbatch exhibits high electrical conductivity and mechanical properties.

[0129] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A conductive masterbatch, characterized in that: The conductive masterbatch is prepared from raw materials comprising, by mass percentage, 48% to 82.25% of polyamide, 1% to 5% of micron-sized silicone microspheres, 15.5% to 40% of conductive filler, and 1.25% to 7% of additives. Wherein, the conductive filler is conductive carbon black.

2. The conductive masterbatch according to claim 1, characterized in that The preparation raw materials include 60% to 82% of the polyamide, 1% to 5% of the micron-sized organic silicon microspheres, 15.5% to 30% of the conductive filler and 1.5% to 5% of the auxiliary agent.

3. The conductive masterbatch according to claim 1 or 2, characterized in that: The particle size of the conductive carbon black is 20nm to 30nm, and the nitrogen adhesion specific surface area of the conductive carbon black is 120m 2 / g~1000m 2 / g, the DBP absorption of the conductive carbon black is 120cm 3 / 100g~500cm 3 / 100g, the pH value of the conductive carbon black is 6-9.

4. The conductive masterbatch according to claim 1 or 2, characterized in that: The particle size of the micron-sized organic silicon microspheres does not exceed 5 μm.

5. The conductive masterbatch according to claim 1 or 2, characterized in that: The auxiliary agent comprises 0.5% to 3% of a lubricant, 0.25% to 2% of an antioxidant and 0.5% to 2% of a dispersant.

6. The conductive masterbatch according to claim 5, characterized in that The lubricant comprises at least one of stearic acid, calcium stearate, magnesium stearate, zinc stearate, paraffin wax, Fischer-Tropsch wax, EVA wax, OP wax, polyethylene wax, Honeywell wax, white oil, chlorinated polyethylene wax, S wax, D wax, DP wax, L wax, oleamide, N,N'-methylene bisstearamide, N,N'-ethylene bisstearamide and metal soap; and / or, the antioxidant comprises at least one of antioxidant 1076, antioxidant 1010, antioxidant 168, antioxidant 1098, antioxidant 264, antioxidant 2246, antioxidant 330, antioxidant 300, antioxidant 505, antioxidant CA, antioxidant STA-1, antioxidant WPS, antioxidant DLTDP, antioxidant DSTDP, antioxidant ODP, antioxidant TNP, antioxidant A, antioxidant D, antioxidant 228, antioxidant NBC, and antioxidant DNP; And / or, the dispersant includes at least one of BYK DISPERBYK-161, Hepfer DS-165A and Clariant DISPERSOGEN-2774.

7. A method for preparing a conductive masterbatch according to any one of claims 1 to 6, characterized in that: The following steps are involved: The prepared raw materials are mixed and then extruded and granulated.

8. The preparation method according to claim 7, characterized in that The mix includes: First, the polyamide is mixed with the additives, then the silicone microspheres are added and mixed further, and finally the conductive filler is mixed.

9. The preparation method according to claim 7 or 8, characterized in that Extrusion granulation includes: First extrude in a twin-screw extruder and then pelletize; Among them, the temperature of the first zone of the twin-screw extruder is 220℃~240℃, the temperature of the second to sixth zones is 230℃~250℃, the temperature of the die head is 240℃~260℃, the main engine speed is 180rpm~220rpm, and the feeding speed is 4Hz~8Hz; The pelletizing speed is 6Hz to 20Hz.

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