Flexible PVC (polyvinyl chloride) protective layer for heating cable and preparation method of flexible PVC protective layer
By combining reactive plasticizers with modified silica, the problem of easy migration of traditional plasticizers at high temperatures is solved, achieving high-temperature stability and flexibility of the PVC protective layer, thus meeting the requirements for long-term safe use of heating cables.
Patent Information
- Application Number
- CN202610014734.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-07
- Publication Date
- 2026-02-17
AI Technical Summary
Traditional non-reactive plasticizers are prone to migration and volatilization at high temperatures, causing the PVC layer to harden and become brittle, resulting in a decline in material performance, shortening the service life of cables, and increasing safety risks.
A reactive plasticizer is used to form a covalent cross-linked network by undergoing a free radical grafting reaction with the PVC molecular chain, and then enhances the interfacial bonding force by undergoing a ring-opening addition reaction with the modified silica surface. Combined with composite heat stabilizers and antioxidants, the thermal stability and flexibility of the material are improved.
The resulting PVC protective layer exhibits extremely low plasticizer migration loss at high temperatures, long thermal stability time, and high mechanical property retention, meeting the requirements for long-term safe use.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of heating cable materials, and relates to a flexible PVC protective layer for a heating cable and a preparation method thereof. BACKGROUND
[0002] As a core insulation and sheath material of a heating cable, a polyvinyl chloride (PVC) layer plays a key role in electrical insulation, mechanical protection, resistance to environmental aging, and imparting flexibility to the cable, and needs to be adapted to a long-term working temperature to ensure safe and stable operation of the cable throughout the entire service period. As a core additive for preparing the flexible PVC layer, a plasticizer can not only significantly improve the processing performance of the material and impart good bending characteristics to the finished product, but also optimize the mechanical balance and synergistically enhance the environmental resistance, thereby meeting the laying requirements in complex application scenarios. However, the traditional non-reactive plasticizer is combined with the PVC matrix only by means of intermolecular forces, lacks the stable anchoring of covalent bonds, and is therefore prone to migration, volatilization or extraction by the medium under harsh service conditions such as long-term high temperature. This phenomenon will gradually harden and embrittle the PVC layer, resulting in a significant reduction in the performance of the material, which not only shortens the service life of the cable, but also increases the potential safety risk. SUMMARY
[0003] The purpose of the present application is to provide a flexible PVC protective layer for a heating cable and a preparation method thereof. The PVC protective layer prepared by the present application has excellent tensile strength and elongation at break, good flexibility and bending resistance, extremely low migration loss rate of the plasticizer at high temperature, long thermal stabilization time, high mechanical property retention rate after long-term high-temperature service, uniform filler dispersion, and stable and reliable overall performance, and can fully meet the long-term safe use requirements of the heating cable.
[0004] The purpose of the present application can be achieved by the following technical solutions:
[0005] A flexible PVC protective layer for a heating cable comprises the following components by weight fraction:
[0006] 100-120 parts of polyvinyl chloride resin, 21-28 parts of reactive plasticizer, 3-5 parts of composite thermal stabilizer, 4-6 parts of toughening agent, 1-3 parts of pretreated silicon dioxide, 0.2-0.25 parts of initiator, 5-8 parts of epoxy soybean oil, 0.5-0.6 parts of lubricant, and 0.2-0.3 parts of antioxidant.
[0007] As a preferred technical solution of the present application, the polyvinyl chloride resin has a model of PVC, S-1000, and is purchased from Qilu Petrochemical; and the initiator is a mixture of dibenzoyl peroxide and triallyl isocyanurate in a mass ratio of 2:1.
[0008] As a preferred technical scheme of the present application, the epoxy value of the epoxy soybean oil is greater than or equal to 6.0%, and the acid value is less than or equal to 0.5 mgKOH / g.
[0009] As a preferred technical scheme of the present application, the lubricant is polyethylene wax.
[0010] As a preferred technical scheme of the present application, the composite heat stabilizer is formed by mixing calcium stearate and zinc stearate at a mass ratio of 3:1.
[0011] As a preferred technical scheme of the present application, the toughening agent is MBS.
[0012] As a preferred technical scheme of the present application, the antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076.
[0013] As a preferred technical scheme of the present application, the preparation method of the reaction-type plasticizer comprises the following steps:
[0014] The bis-epoxy siloxane, cashew phenol, and anhydrous solvent are mixed, a catalyst is added, and then mechanical stirring is performed under heating, the solvent is removed by rotary evaporation, extraction is performed with ethyl acetate, washing is performed, and the organic layer is rotary evaporated to obtain the product.
[0015] As a preferred technical scheme of the present application, the use amount ratio of the bis-epoxy siloxane, cashew phenol, anhydrous solvent, and catalyst is 2.2-2.5 g:3.0-3.6 g:35-40 mL:0.028-0.030 g, the anhydrous solvent is anhydrous tetrahydrofuran, the catalyst is butyltriphenylphosphonium bromide, and the cashew phenol is purchased from Shandong Haobo.
[0016] As a preferred technical scheme of the present application, the use amount of the ethyl acetate is 10 times the mass of the cashew phenol, the temperature of the mechanical stirring under heating is 40-45°C, the stirring speed is 400 rpm, the stirring time is 2.5-3.0 h, and the washing is performed twice with deionized water and saturated NaCl solution respectively.
[0017] As a preferred technical scheme of the present application, the bis-epoxy siloxane is 1,1,3,3-tetramethyl-1,3-bis[3-(epoxyethylmethoxy)propyl]disiloxane, CAS: 126-80-7.
[0018] As a preferred technical scheme of the present application, the preparation of the pretreated silicon dioxide comprises the following steps: mixing fumed silicon dioxide and a sodium hydroxide solution, and then performing thermal soaking, and cooling to obtain the pretreated silicon dioxide.
[0019] As a preferred technical scheme of the present application, the fumed silicon dioxide has a uniform particle size of 15 nm and a specific surface area of 200 m 2 / g.
[0020] As a preferred embodiment of the present invention, the hot soaking is performed at 35-40℃ for 1-1.5 hours, the concentration of the sodium hydroxide solution is 2wt%, and the ratio of fumed silica to sodium hydroxide solution is 1g:18mL.
[0021] As a preferred embodiment of the present invention, a method for preparing a flexible PVC protective layer for heating cables includes the following steps:
[0022] a. First, add polyvinyl chloride resin, composite heat stabilizer, toughening agent, pretreated silica, epoxidized soybean oil, lubricant and antioxidant to a high-speed mixer, mix at 300-500 r / min for 2-3 min, then heat to 80-90℃ and mix at 1000-1200 r / min for 6-8 min to obtain a premix.
[0023] b. Add initiator and reactive plasticizer to the premix and mix at 40-50℃ for 3-4 minutes. Place it in an internal mixer and mix at 170-190℃ and 50-80r / min for 8-12 minutes. Then place it in an extruder and melt extrude at 180-190℃ and 30-50r / min. The preparation is now complete.
[0024] The beneficial effects of this invention are:
[0025] The PVC protective layer prepared by this invention has excellent tensile strength and elongation at break, good flexibility and bending resistance, extremely low plasticizer migration loss rate at high temperature, long thermal stability time, high mechanical property retention rate after long-term high-temperature service, uniform filler dispersion, and stable and reliable overall performance, which can fully meet the long-term safe use requirements of heating cables. Detailed Implementation
[0026] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.
[0027] Example 1
[0028] A flexible PVC protective layer for heating cables comprises the following components in parts by weight:
[0029] The ingredients are: 100 parts polyvinyl chloride resin, 21 parts reactive plasticizer, 3 parts composite heat stabilizer, 4 parts toughening agent, 1 part pretreated silica, 0.2 parts initiator, 5 parts epoxidized soybean oil, 0.5 parts lubricant, and 0.2 parts antioxidant.
[0030] The initiator is a mixture of benzoyl peroxide and triallyl isocyanurate in a mass ratio of 2:1.
[0031] The lubricant is polyethylene wax;
[0032] The composite heat stabilizer is composed of calcium stearate and zinc stearate mixed in a mass ratio of 3:1;
[0033] The toughening agent is MBS;
[0034] The antioxidant is antioxidant 1010.
[0035] The preparation method of the reactive plasticizer includes the following steps:
[0036] Diepoxysiloxane, cashew phenol and anhydrous solvent were mixed, and the catalyst was added. The mixture was stirred at 40°C and 400 rpm for 2.5 h. The solvent was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed twice with deionized water and saturated NaCl solution, and the organic layer was taken and rotary evaporated to obtain the final product.
[0037] The ratio of the amount of the diepoxysiloxane, cashew nut phenol, anhydrous solvent, and catalyst is 2.2g:3.0g:35mL:0.028g, the anhydrous solvent is anhydrous tetrahydrofuran, the catalyst is butyltriphenylphosphine bromide, and the amount of ethyl acetate is 10 times the mass of cashew nut phenol.
[0038] The preparation of the pretreated silica includes: mixing fumed silica and sodium hydroxide solution, soaking at 35°C for 1 hour, and cooling to room temperature to obtain pretreated silica.
[0039] The sodium hydroxide solution has a concentration of 2 wt%, the ratio of fumed silica to sodium hydroxide solution is 1 g:18 mL, and the fumed silica has an average particle size of 15 nm and a specific surface area of 200 m². 2 / g.
[0040] A method for preparing a flexible PVC protective layer for heating cables includes the following steps:
[0041] a. First, add polyvinyl chloride resin, composite heat stabilizer, toughening agent, pretreated silica, epoxidized soybean oil, lubricant and antioxidant to a high-speed mixer, mix at 300 r / min for 2 min, heat to 80℃ and mix at 1000 r / min for 6 min to obtain a premix.
[0042] b. Add initiator and reactive plasticizer to the premix and mix at 40°C for 3 minutes. Place it in an internal mixer and mix at 170°C and 50 r / min for 8 minutes. Then place it in an extruder and melt-extrude at 180°C and 30 r / min. The preparation is now complete.
[0043] Example 2
[0044] A flexible PVC protective layer for heating cables comprises the following components in parts by weight:
[0045] The composition includes 110 parts polyvinyl chloride resin, 24 parts reactive plasticizer, 4 parts composite heat stabilizer, 5 parts toughening agent, 2 parts pretreated silica, 0.22 parts initiator, 6 parts epoxidized soybean oil, 0.55 parts lubricant, and 0.25 parts antioxidant.
[0046] The initiator is a mixture of benzoyl peroxide and triallyl isocyanurate in a mass ratio of 2:1.
[0047] The lubricant is polyethylene wax;
[0048] The composite heat stabilizer is composed of calcium stearate and zinc stearate mixed in a mass ratio of 3:1;
[0049] The toughening agent is MBS;
[0050] The antioxidant is antioxidant 1010.
[0051] The preparation method of the reactive plasticizer includes the following steps:
[0052] Diepoxysiloxane, cashew phenol and anhydrous solvent were mixed, and the catalyst was added. The mixture was stirred at 42℃ and 400rpm for 2.8h. The solvent was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed twice with deionized water and saturated NaCl solution, and the organic layer was taken and rotary evaporated to obtain the final product.
[0053] The ratio of the amount of the diepoxysiloxane, cashew nut phenol, anhydrous solvent, and catalyst is 2.4g:3.3g:38mL:0.029g, the anhydrous solvent is anhydrous tetrahydrofuran, the catalyst is butyltriphenylphosphine bromide, and the amount of ethyl acetate is 10 times the mass of cashew nut phenol.
[0054] The preparation of the pretreated silica includes: mixing fumed silica and sodium hydroxide solution, soaking at 42°C for 1.2 hours, and cooling to room temperature to obtain pretreated silica.
[0055] The sodium hydroxide solution has a concentration of 2 wt%, the ratio of fumed silica to sodium hydroxide solution is 1 g:18 mL, and the fumed silica has an average particle size of 15 nm and a specific surface area of 200 m². 2 / g.
[0056] A method for preparing a flexible PVC protective layer for heating cables includes the following steps:
[0057] a. First, add polyvinyl chloride resin, composite heat stabilizer, toughening agent, pretreated silica, epoxidized soybean oil, lubricant and antioxidant to a high-speed mixer, mix at 400 r / min for 2.5 min, heat to 85℃, mix at 1100 r / min for 7 min to obtain premix;
[0058] b. Add initiator and reactive plasticizer to the premix and mix at 45°C for 3.5 min. Place it in an internal mixer and mix at 180°C and 65 r / min for 10 min. Then place it in an extruder and melt extrude at 185°C and 40 r / min. The preparation is now complete.
[0059] Example 3
[0060] A flexible PVC protective layer for heating cables comprises the following components in parts by weight:
[0061] The composition includes 120 parts polyvinyl chloride resin, 28 parts reactive plasticizer, 5 parts composite heat stabilizer, 6 parts toughening agent, 3 parts pretreated silica, 0.25 parts initiator, 8 parts epoxidized soybean oil, 0.6 parts lubricant, and 0.3 parts antioxidant.
[0062] The initiator is a mixture of benzoyl peroxide and triallyl isocyanurate in a mass ratio of 2:1.
[0063] The lubricant is polyethylene wax;
[0064] The composite heat stabilizer is composed of calcium stearate and zinc stearate mixed in a mass ratio of 3:1;
[0065] The toughening agent is MBS;
[0066] The antioxidant is antioxidant 1010.
[0067] The preparation method of the reactive plasticizer includes the following steps:
[0068] Diepoxysiloxane, cashew phenol and anhydrous solvent were mixed, and after adding the catalyst, the mixture was stirred at 45℃ and 400rpm for 3.0h. The solvent was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed twice with deionized water and saturated NaCl solution, and the organic layer was taken and rotary evaporated to obtain the final product.
[0069] The ratio of the amount of the diepoxysiloxane, cashew nut phenol, anhydrous solvent, and catalyst is 2.5g:3.6g:40mL:0.030g, the anhydrous solvent is anhydrous tetrahydrofuran, the catalyst is butyltriphenylphosphine bromide, and the amount of ethyl acetate is 10 times the mass of cashew nut phenol.
[0070] The preparation of the pretreated silica includes: mixing fumed silica and sodium hydroxide solution, soaking at 40°C for 1.5 hours, and cooling to room temperature to obtain pretreated silica.
[0071] The sodium hydroxide solution has a concentration of 2 wt%, the ratio of fumed silica to sodium hydroxide solution is 1 g:18 mL, and the fumed silica has an average particle size of 15 nm and a specific surface area of 200 m². 2 / g.
[0072] A method for preparing a flexible PVC protective layer for heating cables includes the following steps:
[0073] a. First, add polyvinyl chloride resin, composite heat stabilizer, toughening agent, pretreated silica, epoxidized soybean oil, lubricant and antioxidant to a high-speed mixer, mix at 500 r / min for 3 min, heat to 90℃, mix at 1200 r / min for 8 min to obtain premix;
[0074] b. Add initiator and reactive plasticizer to the premix and mix at 50°C for 4 minutes. Place it in an internal mixer and mix at 190°C and 80 r / min for 12 minutes. Then place it in an extruder and melt-extrude at 190°C and 50 r / min. The preparation is now complete.
[0075] Comparative Example 1
[0076] Compared with Example 3, Comparative Example 1 used diepoxysiloxane instead of reactive plasticizer, while the remaining components, preparation steps and parameters were the same.
[0077] Comparative Example 2
[0078] Compared with Example 3, Comparative Example 2 used cashew phenol reactive plasticizer, while the other components, preparation steps and parameters were the same.
[0079] Comparative Example 3
[0080] Compared with Example 3, Comparative Example 3 used fumed silica instead of pretreated silica, while the other components, preparation steps and parameters were the same.
[0081] Comparative Example 4
[0082] Compared with Example 3, Comparative Example 4 used dioctyl terephthalate instead of reactive plasticizer, while the remaining components, preparation steps and parameters were the same.
[0083] Comparative Example 5
[0084] Compared with Example 3, Comparative Example 5 used dioctyl sebacate instead of reactive plasticizer, while the remaining components, preparation steps and parameters were the same.
[0085] The PVC materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested, and the test results are shown in Table 1.
[0086] Tensile strength and elongation at break tests: in accordance with GB / T 2951.11-2008;
[0087] Migration loss rate: based on ISO 177 2005 (hot air drying oven method);
[0088] Stability time of Congo Red Heat: HG / T 3862-2006.
[0089] Table 1. Material Performance Test Results
[0090]
[0091] As can be seen from the test results in Table 1, compared with Comparative Examples 1-5, the PVC material prepared by the present invention has significantly higher thermal stability, is less prone to migration, and has excellent mechanical strength and elongation at break.
[0092] This invention utilizes cashew phenol / diepoxysiloxane containing carbon-carbon double bonds and epoxy groups as a reactive plasticizer. Under the action of an initiator, its carbon-carbon double bonds undergo a free radical grafting reaction with the PVC molecular chain to form a covalent cross-linked network, achieving molecular-level anchoring of the plasticizer to reduce migration risk. Simultaneously, its epoxy groups undergo a ring-opening addition reaction with the abundant hydroxyl groups on the surface of silica modified with hydrochloric acid, promoting the uniform dispersion of silica in the PVC matrix and strengthening the interfacial bonding between inorganic fillers and the organic matrix, synergistically improving the material's mechanical strength and flexibility. Furthermore, the epoxy groups of the reactive plasticizer can capture HCl generated by the thermal decomposition of PVC, forming a synergistic thermal stabilizing effect with the calcium stearate / zinc stearate composite heat stabilizer. Combined with antioxidant 1010 to inhibit oxidative degradation, this further enhances the material's thermal stability and long-term heat resistance.
[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A flexible PVC protective layer for heat generating cables, characterized in that, The following components are included by weight parts: 100-120 parts of polyvinyl chloride resin, 21-28 parts of reactive plasticizer, 3-5 parts of composite heat stabilizer, 4-6 parts of toughening agent, 1-3 parts of pretreated silica, 0.2-0.25 parts of initiator, 5-8 parts of epoxy soybean oil, 0.5-0.6 parts of lubricant, and 0.2-0.3 parts of antioxidant; The preparation method of the reactive plasticizer comprises the following steps: The bis-epoxy siloxane, cardanol and anhydrous solvent are mixed, and after adding a catalyst, the mechanical stirring is heated, the solvent is removed by rotary evaporation, extracted with ethyl acetate, washed, and the organic layer is rotary evaporated to obtain the product.
2. A flexible PVC protective layer for heat generating cables according to claim 1, characterized in that: The initiator is a mixture of dibenzoyl peroxide and triallyl isocyanurate in a mass ratio of 2:
1.
3. A flexible PVC protective layer for heat generating cables according to claim 1, characterized in that: The lubricant is polyethylene wax, and the composite heat stabilizer is a mixture of calcium stearate and zinc stearate in a mass ratio of 3:
1.
4. The flexible PVC protective layer for heat generating cable according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 1010, antioxidant 168 and antioxidant 1076.
5. The flexible PVC protective layer for heat generating cable according to claim 1, characterized in that: The amount ratio of the bis-epoxy siloxane, cardanol, anhydrous solvent and catalyst is 2.2-2.5g:3.0-3.6g:35-40mL:0.028-0.030g, the anhydrous solvent is anhydrous tetrahydrofuran, and the catalyst is butyltriphenylphosphonium bromide.
6. A flexible PVC protective layer for heat generating cables according to claim 1, characterized in that: The amount of ethyl acetate is 10 times the mass of cardanol; the temperature of the mechanical stirring is 40-45℃, the stirring speed is 400rpm, and the stirring time is 2.5-3.0h, and the washing is performed with deionized water and saturated NaCl solution for 2 times respectively.
7. A flexible PVC protective layer for heat generating cables according to claim 1, characterized in that The preparation of the pretreated silica comprises: mixing fumed silica and sodium hydroxide solution and then performing heat soaking, and after cooling, the pretreated silica is obtained.
8. A flexible PVC protective layer for heat generating cables according to claim 7, characterized in that: The heat soaking is performed at 35-40℃ for 1-1.5h, the concentration of the sodium hydroxide solution is 2wt%, and the amount ratio of the fumed silica and sodium hydroxide solution is 1g:18mL.
9. A process for the preparation of a flexible PVC jacket for heat generating cables as claimed in any one of claims 1 to 8, characterized in that, The preparation method comprises the following steps: a. First, the polyvinyl chloride resin, composite heat stabilizer, toughening agent, pretreated silica, epoxy soybean oil, lubricant and antioxidant are added to a high-speed mixer, mixed at 300-500r / min for 2-3min, heated to 80-90℃, and mixed at 1000-1200r / min for 6-8min to obtain a premix; b. The initiator and reactive plasticizer are added to the premix and mixed at 40-50℃ for 3-4min, placed in a banbury mixer at a temperature of 170-190℃ and a rotation speed of 50-80r / min for 8-12min, and then placed in an extruder at a temperature of 180-190℃ and a screw rotation speed of 30-50r / min for melt extrusion, and the preparation is completed.