Preparation method of shielding material suitable for high carbon black filling amount and high white oil amount

Abstract

The invention relates to a preparation method of a shielding material suitable for high carbon black filling amount and high white oil amount. The preparation method comprises the following steps: S1, preparing a formula; s2, in the process of adding the conductive carbon black into the closed mixing device, white oil is sprayed to the surface of the conductive carbon black according to the formula proportion while stirring is conducted, and conductive carbon black particles containing the white oil are obtained; s3, the EVA resin, the white oil-containing conductive carbon black and the auxiliaries are put into reciprocating mixing equipment through a weightlessness type feeding scale; s4, extruding and granulating the mixed material, and then dehydrating and drying to obtain semi-finished product particles; s5, blending the semi-finished product particles with a peroxide cross-linking agent at a low speed through a shaking tank, wherein the peroxide cross-linking agent is fully absorbed; and S6, removing powder and irregular large particles from the semi-finished product particles absorbing the peroxide cross-linking agent to obtain a finished product with moderate particle size. According to the invention, after oil absorption, the carbon black is still granular, but is not easy to drift away; the white oil is absorbed by the carbon black and does not overflow.

Description

Technical Field

[0001] The invention relates to the technical field of cable shielding materials, in particular to a method for preparing shielding materials suitable for high carbon black filling content and high white oil content. Background Art

[0002] In order to achieve excellent volume resistivity of cable shielding materials, the content of conductive carbon black needs to be increased during shielding material formulation design. However, increasing the content of conductive carbon black will lead to two problems: First, conductive carbon black is a substance that easily disperses. During production, part of the dispersed carbon black will be absorbed by the dust removal device. When the carbon black reaches a certain amount, it will also leak out from the air holes of the equipment. This results in the actual amount of carbon black added to the formula being less than the designed amount.

[0003] Second, the increase in the content of conductive carbon black will lead to poor fluidity of the shielding material, and it is often necessary to add lubricants to improve fluidity. The most commonly used lubricant in shielding materials is white oil, and the direct addition of white oil is also limited. Once it exceeds a certain amount, it cannot be completely mixed with the base material and will overflow from the gaps in the equipment. This results in the actual amount of white oil added to the formula being less than the designed amount. Summary of the invention

[0004] The object of the present invention is to solve the above problems and provide a method for preparing a shielding material suitable for high carbon black filling content and high white oil content.

[0005] The present invention provides the following technical solutions: A method for preparing a shielding material suitable for high carbon black filling and high white oil content, characterized in that it comprises the following steps: S1. Prepare a formula, which includes the following components in proportion by weight: 50-55 parts of EVA resin, 36-40 parts of conductive carbon black, 8-10 parts of white oil, 1-2 parts of additives, and 1-2 parts of peroxide crosslinking agent; S2, in the process of adding 36-40 parts of conductive carbon black to the closed mixing device, spray 8-10 parts of white oil on the surface of the conductive carbon black according to the formula ratio in step S1 while stirring, and close and stir for 30 minutes to combine the conductive carbon black and the white oil into 44-50 parts of conductive carbon black particles containing white oil that are not adhered to each other; S3, 50-55 parts of EVA resin, 44-50 parts of conductive carbon black containing white oil, and 1-2 parts of additives are respectively put into a reciprocating mixing equipment through a loss-in-weight feeding scale for plasticizing and mixing, and the mixing temperature is not less than 160°C; S4, extruding the mixed material in step S3 through a single screw extruder, and granulating through an underwater cutting system, the water temperature used in the underwater cutting system is controlled at 50° C., and then dehydrating and drying through a centrifugal dehydrator to obtain semi-finished granules; S5. The semi-finished granules are mixed with 1-2 parts of a peroxide cross-linking agent at a temperature of 50-55° C. for half an hour at a low speed, and the peroxide cross-linking agent is fully absorbed; S6. The semi-finished particles that have absorbed the peroxide crosslinking agent are passed through a boiling bin and a vibrating screen to remove powder and irregular large particles, thereby obtaining a finished product with a moderate particle size, that is, a shielding material with a high carbon black filling content and a high white oil content.

[0006] In step S1, the auxiliary agent contains a lubricant, an antioxidant, and an anti-copper agent, and is a mixture obtained by mixing substances including the lubricant, the antioxidant, and the anti-copper agent.

[0007] In step S6, the shielding material with high carbon black filling amount and high white oil content obtained has a carbon black content of 36% to 40% and a white oil content of 8% to 10%.

[0008] The method of the present invention is advanced and scientific. Through the present invention, the high oil absorption value of conductive carbon black is utilized to allow the conductive carbon black to absorb white oil in advance. After the oil absorption, the carbon black is still in granular form, but is not easy to disperse, thereby solving the problem of formula content loss caused by dispersion of carbon black; and the white oil has been absorbed by the carbon black and will not overflow, thereby also solving the problem of formula content loss caused by overflow of white oil.

[0009] The beneficial effects of the present invention are: 1. Taking advantage of the high oil absorption value of conductive carbon black, the conductive carbon black and white oil are combined to form carbon black particles containing white oil, which remain in granular form and do not affect the original measurement method.

[0010] 2. This new type of carbon black particles are no longer light because they have absorbed white oil, thus solving the problem of the original carbon black being easily dispersed.

[0011] 3. Because the white oil is adsorbed by the conductive carbon black in advance and mixed with the base material together with the carbon black, it will no longer overflow, thus solving the problem of easy overflow of the original white oil.

[0012] 4. Because the above problems of conductive carbon black and white oil are solved, the consumption of conductive carbon black and white oil is reduced, and the formula ratio is made more accurate. DETAILED DESCRIPTION

[0013] The present invention is described in detail below.

[0014] A method for preparing shielding materials with high carbon black filling content and high white oil content, which is suitable for shielding materials with carbon black content of 36% to 40% and white oil content of 8% to 10%. The specific steps are as follows: S1. Prepare a formula, which includes the following components in proportion by weight: 50-55 parts of EVA resin, 36-40 parts of conductive carbon black, 8-10 parts of white oil, 1-2 parts of additives (a mixture of lubricants, antioxidants, anti-copper agents, etc.), and 1-2 parts of peroxide crosslinking agents; S2, in the process of adding 36-40 parts of conductive carbon black to the closed mixing device, spray 8-10 parts of white oil on the surface of the conductive carbon black according to the formula ratio in step S1 while stirring, and close and stir for 30 minutes to combine the conductive carbon black and the white oil into 44-50 parts of conductive carbon black particles containing white oil that are not adhered to each other; S3, 50-55 parts of EVA resin, 44-50 parts of conductive carbon black containing white oil, and 1-2 parts of additives are respectively fed into a reciprocating mixing equipment in proportion through a high-precision weightlessness feeding scale for plasticizing and mixing, and the mixing material temperature is not less than 160°C; S4, extruding the mixed material in step S3 through a single screw extruder, and granulating through an underwater cutting system, the water temperature used in the underwater cutting system is controlled at 50° C., and then dehydrating and drying through a centrifugal dehydrator to obtain semi-finished granules; S5. The semi-finished granules are mixed with 1-2 parts of a peroxide cross-linking agent at a temperature of 50-55° C. for half an hour at a low speed, and the peroxide cross-linking agent is fully absorbed; S6. The semi-finished particles that have absorbed the peroxide cross-linking agent are passed through a boiling bin and a vibrating screen to remove powder and irregular large particles, thereby obtaining a finished product with a moderate particle size.

[0015] This method allows the conductive carbon black to absorb the white oil in advance. After absorbing the oil, the carbon black is still in granular form, but it is not easy to disperse, thus solving the problem of formula content loss caused by dispersion of carbon black. The white oil has been absorbed by the carbon black and will not overflow, thus solving the problem of formula content loss caused by overflow of white oil.

[0016] The examples given above are used to explain and introduce the present invention in detail, but the present invention is not limited to the above specific implementation examples. Any changes or modifications made based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A method for preparing a shielding material suitable for high carbon black filling and high white oil content, characterized in that: The following steps are involved: S1. Prepare a formula, which includes the following components in proportion by weight: 50-55 parts of EVA resin, 36-40 parts of conductive carbon black, 8-10 parts of white oil, 1-2 parts of additives, and 1-2 parts of peroxide crosslinking agent; S2, in the process of adding 36-40 parts of conductive carbon black to the closed mixing device, spray 8-10 parts of white oil on the surface of the conductive carbon black according to the formula ratio in step S1 while stirring, and close and stir for 30 minutes to combine the conductive carbon black and the white oil into 44-50 parts of conductive carbon black particles containing white oil that are not adhered to each other; S3, 50-55 parts of EVA resin, 44-50 parts of conductive carbon black containing white oil, and 1-2 parts of additives are respectively put into a reciprocating mixing equipment through a loss-in-weight feeding scale for plasticizing and mixing, and the mixing temperature is not less than 160°C; S4, extruding the mixed material in step S3 through a single screw extruder, and granulating through an underwater cutting system, the water temperature used in the underwater cutting system is controlled at 50° C., and then dehydrating and drying through a centrifugal dehydrator to obtain semi-finished granules; S5. The semi-finished granules are mixed with 1-2 parts of a peroxide cross-linking agent at a temperature of 50-55° C. for half an hour at a low speed, and the peroxide cross-linking agent is fully absorbed; S6. The semi-finished particles that have absorbed the peroxide crosslinking agent are passed through a boiling bin and a vibrating screen to remove powder and irregular large particles, thereby obtaining a finished product with a moderate particle size, that is, a shielding material with a high carbon black filling content and a high white oil content.

2. The method for preparing a shielding material suitable for high carbon black filling and high white oil content according to claim 1, characterized in that: In step S1, the auxiliary agent contains a lubricant, an antioxidant, and an anti-copper agent, and is a mixture obtained by mixing substances including the lubricant, the antioxidant, and the anti-copper agent.

3. The method for preparing a shielding material suitable for high carbon black filling and high white oil content according to claim 1, characterized in that: In step S6, the shielding material with high carbon black filling amount and high white oil content obtained has a carbon black content of 36% to 40% and a white oil content of 8% to 10%.