Migration-resistant low-shrinkage PVC (Polyvinyl Chloride) composition for coaxial cable as well as preparation method and application thereof

Abstract

The invention relates to a migration-resistant low-shrinkage PVC (polyvinyl chloride) composition for a coaxial cable as well as a preparation method and application of the migration-resistant low-shrinkage PVC composition. The migration-resistant low-shrinkage PVC composition comprises the following raw material components in parts by weight: 100 parts of polyvinyl chloride resin; 20 to 30 parts of chlorinated polyvinyl chloride resin; 45-60 parts of a special plasticizer; 8-12 parts of a stabilizer; 1-2 parts of an antioxidant; 0.5 to 1.0 part of a lubricant; 1-3 parts of a first plasticizer; and 20-30 parts of calcium carbonate. The special raw materials are combined, so that the material has excellent migration resistance, low shrinkage, cold resistance and good electrical insulation performance, and the problems of influence of migration of small molecular substances on signal transmission and large shrinkage of the cable in the conventional automobile coaxial cable are solved.

Description

Technical Field

[0001] The present invention relates to a PVC composition, in particular to a migration-resistant and low-shrinkage PVC composition for coaxial cables, and a preparation method and application thereof. Background Art

[0002] Automotive coaxial cable is a specialized cable used to transmit signals within automotive electronic systems. It typically consists of a center conductor, insulation, shielding, and jacket. This structure confines high-frequency signals to the space between the center conductor and the shield. The shield effectively blocks external electromagnetic interference and prevents internal signal leakage, thereby ensuring high-quality signal transmission. Automotive coaxial cable offers strong anti-interference capabilities, high signal transmission quality, and exceptional reliability.

[0003] Currently, automotive coaxial cables face two main problems: (1) small molecules in the sheath migrate into the shield, affecting signal transmission quality; and (2) the sheath shrinks significantly, causing the shield to leak out of both ends of the finished cable. This poor shielding provides adequate protection, impacting electromagnetic interference and signal transmission. Therefore, it is highly desirable to develop a migration-resistant, low-shrinkage PVC composition for automotive coaxial cables.

[0004] Chinese invention patent application number 202510009301.9 discloses a migration-resistant, environmentally friendly flexible PVC sheathed cable, comprising one or more core units, each core unit comprising a conductor core, a shielding layer coaxially tightly wrapped around the conductor core, and an insulating layer coaxially tightly wrapped around the shielding layer. All core units are twisted together as a whole, coaxially tightly wrapped by a flame-retardant layer, and a PVC sheath layer coaxially tightly wrapped around the flame-retardant layer. Polyacrylate-based phthalate molecular imprinted microspheres are distributed in the PVC sheath layer. These imprinted microspheres form binding and restraint on the phthalate plasticizer molecules in the sheath, thereby reducing the migration of plasticizer molecules in the cable sheath to the cable surface. However, the imprinted microspheres need to be prepared, and the cost, process conditions, etc. are very high. Summary of the Invention

[0005] In view of the shortcomings of the existing technical routes, the present invention aims to provide a migration-resistant and low-shrinkage PVC composition for coaxial cables.

[0006] In order to achieve the above object, the present invention provides a migration-resistant and low-shrinkage PVC composition for coaxial cables, which comprises the following raw material components in parts by weight:

[0007] 100 parts of polyvinyl chloride resin;

[0008] 20-30 parts of chlorinated polyvinyl chloride resin;

[0009] 45-60 parts of special plasticizer;

[0010] 8-12 parts of stabilizer;

[0011] 1-2 parts of antioxidant;

[0012] 0.5-1.0 parts of lubricant;

[0013] 1 to 3 parts of the first plasticizer;

[0014] 20-30 parts of calcium carbonate.

[0015] Optimally, the polyvinyl chloride resin is a mixture of one or more selected from Formosa Plastics S-70 and United Plastics US-70; the chlorinated polyvinyl chloride resin is a mixture of one or more selected from 135A and 135B.

[0016] Optimally, the special plasticizer is a mixture of one or more selected from W2050, UN615, PN1030 and TOTM.

[0017] Optimally, the stabilizer is a mixture of one or more selected from ADK RUP167C and RUP110C.

[0018] Optimally, the antioxidant is a mixture of one or more selected from antioxidant 1010 and antioxidant 1076.

[0019] Optimally, the lubricant is a mixture of one or more selected from Honeywell AC6A and Klein PE520.

[0020] Optimally, the first plasticizer is a mixture of one or more selected from HP4051 and HP441, and its melt index is 8 to 12 g / 10 min.

[0021] Optimally, the calcium carbonate is active heavy calcium carbonate, and its average particle size D50 is 0.5 to 2 μm.

[0022] Another object of the present invention is to provide a method for preparing the above-mentioned migration-resistant low-shrinkage PVC composition for coaxial cable, comprising the following steps:

[0023] (a) mixing the polyvinyl chloride resin, chlorinated polyvinyl chloride resin, special plasticizer, stabilizer, antioxidant, lubricant and first plasticizer in a formulated amount at a rotation speed of 700 rpm to 900 rpm;

[0024] (b) heating the product of step (a) to 80° C. to 90° C., adding the formulated amount of calcium carbonate, and stirring and mixing; heating the product to 135° C. to 140° C., feeding the product into a double-stage BUSS reciprocating machine, and extruding and granulating the product;

[0025] Optimally, the control parameters of the two-stage BUSS reciprocating machine are as follows: reciprocating machine temperature is 135-140°C, single screw temperature is 110-140°C, feed rate is 30%, reciprocating machine main engine speed is 480±50rpm, torque is 55-65%, single screw main engine speed is 55±5rpm, torque is 38-50%, pelletizer speed is 600±50rpm, upper stage machine material temperature is 180°C-185°C.

[0026] Another object of the present invention is to provide an application of the above-mentioned migration-resistant and low-shrinkage PVC composition for coaxial cables, which is used to prepare the sheath layer of the coaxial cable.

[0027] Due to the application of the above technical solution, the present invention has the following advantages compared with the existing technology: the migration-resistant and low-shrinkage PVC composition for coaxial cable of the present invention is combined with specific raw materials to make the material have excellent migration resistance, low shrinkage, cold resistance and good electrical insulation performance, thereby solving the problems of small molecular substance migration affecting signal transmission and excessive cable shrinkage in current automotive coaxial cables. DETAILED DESCRIPTION

[0028] The present invention discloses a migration-resistant, low-shrinkage PVC composition for coaxial cables, comprising the following raw material components by weight: 100 parts polyvinyl chloride resin; 20-30 parts chlorinated polyvinyl chloride resin; 45-60 parts special plasticizer; 8-12 parts stabilizer; 1-2 parts antioxidant; 0.5-1.0 parts lubricant; 1-3 parts first plasticizer; and 20-30 parts calcium carbonate. By combining these specific raw materials, the material exhibits excellent migration resistance, low shrinkage, cold resistance, and good electrical insulation properties. This solves the current problems of automotive coaxial cables, such as the migration of small molecules affecting signal transmission and excessive cable shrinkage, and meets the ISO 19642 B-grade standard requirements.

[0029] The polyvinyl chloride resin is a mixture of one or more selected from Formosa Plastics S-70 and Liancheng US-70 (the K value of the PVC resin is 70 and the average degree of polymerization is 1300). The chlorinated polyvinyl chloride resin is a mixture of one or more selected from 135A and 135B (the CPE resin has a chlorine content of 35% and a melting enthalpy of ≤2.0 J / G). The specialty plasticizer is a mixture of one or more selected from W2050, UN615, PN1030, and TOTM. The stabilizer is a mixture of one or more selected from ADKRUP167C and RUP110C. The antioxidant is a mixture of one or more selected from antioxidant 1010 and antioxidant 1076. The lubricant is a mixture of one or more selected from Honeywell AC6A and Klein PE520. The first plasticizer is a mixture of one or more selected from HP4051 and HP441, with a melt index of 8 to 12 g / 10 min. It is an ethylene-n-butyl acrylate-carbonyl terpolymer that can be stably embedded between PVC molecular chains. It works with chlorinated polyvinyl chloride resins and specialty plasticizers to weaken the forces between PVC molecules and increase the mobility of the molecular chains. During the molding and cooling process, it is less likely to migrate out, which alleviates the shrinkage of the molecular chains and further controls material shrinkage. The calcium carbonate is activated ground calcium carbonate with an average particle size (D50) of 0.5 to 2 μm.

[0030] The preparation method of the above-mentioned migration-resistant and low-shrinkage PVC composition for coaxial cable is characterized by comprising the following steps: (a) mixing the polyvinyl chloride resin, chlorinated polyvinyl chloride resin, special plasticizer, stabilizer, antioxidant, lubricant and first plasticizer in the formulated amount at a rotation speed of 700rpm-900rpm; (b) heating the product of step (a) to 80°C-90°C, continuously adding the formulated amount of calcium carbonate and stirring and mixing; heating to 135°C-140°C, feeding into a two-stage BUSS reciprocating machine, and extruding and granulating. The control parameters of the two-stage BUSS reciprocating machine are as follows: reciprocating machine temperature of 135-140°C, single screw temperature of 110-140°C, feed rate of 30%, reciprocating machine main engine speed of 480±50rpm, torque of 55-65%, single screw main engine speed of 55±5rpm, torque of 38-50%, pelletizer speed of 600±50rpm, and upper stage machine material temperature of 180°C-185°C.

[0031] The migration-resistant and low-shrinkage PVC composition for coaxial cable is used to prepare the sheath layer of the coaxial cable.

[0032] The present invention will be further described in detail below with reference to specific examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry.

[0033] Examples 1-5 and Comparative Examples 1-5 respectively provide a migration-resistant, low-shrinkage PVC composition for a coaxial cable. The raw material composition thereof is shown in Table 1, and the PVC composition product is prepared according to the following steps:

[0034] (a) mixing the formulated amounts of polyvinyl chloride resin, chlorinated polyvinyl chloride resin, plasticizer, stabilizer, antioxidant, lubricant, and first plasticizer at a speed of 700 rpm to 900 rpm (this speed range has no effect on product performance; a speed of 800 rpm was used in each embodiment and comparative example);

[0035] (b) The product of step (a) is heated to 80° C. to 90° C. (80° C. is used in each embodiment and comparative example), and the formulated amount of calcium carbonate is continuously added thereto for stirring and mixing (the stirring speed is the same as the above speed). The temperature is raised to 135° C. to 140° C. (135° C. is used in each embodiment and comparative example), and the product is fed into a two-stage BUSS reciprocating machine (the parameters of the two-stage BUSS reciprocating machine fluctuate within the following ranges without affecting the product performance: reciprocating machine temperature 135-140° C., single screw temperature 110-140° C., feed rate 30%, reciprocating machine main engine speed 480±50 rpm, torque 55-65%, single screw main engine speed 55±5 rpm, torque 38-50%, pelletizer speed 600±50 rpm, upper stage machine material temperature 180° C. to 185° C.), and extruded and granulated to obtain a migration-resistant, low-shrinkage PVC composition).

[0036] Table 1 Composition of the migration-resistant low-shrinkage PVC composition for coaxial cables in Examples 1-5 and Comparative Examples 1-5 (Unit: kg)

[0037]

[0038] Note: PVC (polyvinyl chloride resin) is US-70, CPE (chlorinated polyvinyl chloride resin) is 135A, special plasticizer is TOTM, stabilizer is RUP110C, antioxidant is antioxidant 1010, lubricant is Klein PE520, first plasticizer is HP4051, calcium carbonate is activated heavy calcium carbonate (Guangyuan HX-916).

[0039] A coaxial cable was prepared according to a conventional coaxial cable preparation method (see Example 3 of Chinese Invention Patent Application No. 202410858095.4), except that the sheath layer used the migration-resistant, low-shrinkage PVC composition for coaxial cables provided in Examples 1-5 and Comparative Examples 1-5. This was extruded at 150°C through a single-screw extruder with a diameter of 65 mm and an aspect ratio of 25:1 to coat the outer wall of the shielding layer to produce the coaxial cable. The final test results are shown in Table 2.

[0040] Table 2 Performance test table of coaxial cables prepared using the PVC compositions in Examples 1-5 and Comparative Examples 1-5

[0041]

[0042] Note: The test method refers to GB / T8815 and ISO 19642.

[0043] In Examples 1 to 5, from the test results in Table 2, it can be seen that within the normal range, adjusting the amount of CPE, plasticizer, stabilizer, antioxidant, lubricant, anti-shrinkage agent, and calcium carbonate has little effect on the tensile properties of the material.

[0044] Comparing Example 1, Comparative Example 1 and Comparative Example 2, when the amount of CPE is low, the low temperature resistance and elongation at break of the material are unqualified; when the amount of CPE is high, the tensile strength of the material is unqualified.

[0045] Comparing Example 1 with Comparative Example 3, the tensile strength of the material failed to meet the requirements when the amount of special plasticizer added was too high. Excessive addition reduced the material's hardness, weakened the intermolecular forces, and resulted in substandard tensile strength, affecting the long-term service life of the cable. The risk of plasticizer migration also increased with extended use.

[0046] Comparing Example 1, Comparative Example 4, and Comparative Example 5, when the first plasticizer addition level is low, the cable's thermal shrinkage fails the standard and the low-temperature impact catalytic temperature does not meet the requirements. When the first plasticizer addition level is high, the material's tensile strength fails the standard. HP4051 is an ethylene-n-butyl acrylate-carbonyl terpolymer with a molecular weight higher than the plasticizer. During processing, it can stably embed between PVC molecular chains, weakening the intermolecular forces and increasing the mobility of the molecular chains. During the molding and cooling process, it is less likely to migrate out, alleviating the shrinkage of the molecular chains and thus controlling the shrinkage of the material. When the addition level is insufficient, the molecular chains are mainly composed of small molecules of plasticizer, resulting in excessive thermal shrinkage. In addition, an additional comparative example was set up using ethylene-vinyl acetate-carbonyl (E / VA / CO) as the first plasticizer (all other conditions were the same as those disclosed in Example 1). The glass transition temperature of the ethylene-vinyl acetate-carbonyl terpolymer is -32°C, higher than the -54°C of HP4051 and HP441, resulting in the material's unqualified cold resistance.

[0047] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A migration-resistant and low-shrinkage PVC composition for coaxial cable, characterized in that: It includes the following raw material components in parts by weight: 100 parts of polyvinyl chloride resin; 20-30 parts of chlorinated polyvinyl chloride resin; 45~60 parts of special plasticizer; 8~12 parts of stabilizer; 1~2 parts of antioxidant; 0.5~1.0 parts of lubricant; 1-3 parts of the first plasticizer; 20-30 parts of calcium carbonate.

2. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, characterized in that: The polyvinyl chloride resin is a mixture of one or more selected from Formosa Plastics S-70 and United Plastics US-70; the chlorinated polyvinyl chloride resin is a mixture of one or more selected from 135A and 135B.

3. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, characterized in that: The special plasticizer is a mixture of one or more selected from W2050, UN615, PN1030 and TOTM.

4. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, wherein: The stabilizer is a mixture of one or more selected from ADK RUP167C and RUP110C.

5. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, characterized in that: The antioxidant is a mixture of one or more selected from antioxidant 1010 and antioxidant 1076.

6. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, characterized in that: The lubricant is a mixture of one or more selected from Honeywell AC6A and Klein PE520.

7. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, characterized in that: The first plasticizer is a mixture of one or more selected from HP4051 and HP441, and its melt index is 8-12 g / 10 min.

8. The migration-resistant and low-shrinkage PVC composition for coaxial cables according to claim 1, characterized in that: The calcium carbonate is active heavy calcium carbonate, and its average particle size D50 is 0.5-2 μm.

9. The method for preparing the migration-resistant and low-shrinkage PVC composition for coaxial cable according to any one of claims 1 to 8, characterized in that: The following steps are involved: (a) mixing the polyvinyl chloride resin, chlorinated polyvinyl chloride resin, special plasticizer, stabilizer, antioxidant, lubricant and first plasticizer in a formulated amount at a rotation speed of 700 rpm to 900 rpm; (b) heating the product of step (a) to 80°C to 90°C, adding the formulated amount of calcium carbonate, stirring and mixing; heating the product to 135°C to 140°C, feeding the product into a double-stage BUSS reciprocating machine, and extruding and granulating the product; Optimally, the control parameters of the two-stage BUSS reciprocating machine are as follows: reciprocating machine temperature is 135~140℃, single screw temperature is 110~140℃, feed rate is 30%, reciprocating machine main engine speed is 480±50rpm, torque is 55~65%, single screw main engine speed is 55±5rpm, torque is 38~50%, pelletizer speed is 600±50rpm, and upper stage machine material temperature is 180℃~185℃.

10. Use of the migration-resistant and low-shrinkage PVC composition for coaxial cables according to any one of claims 1 to 8, characterized in that: Used to make the sheath layer in coaxial cable.

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