Preparation method of low-cost environment-friendly heat stabilizer

Abstract

The invention relates to the technical field of thermal stability modification of polyvinyl chloride materials, in particular to a preparation method of a low-cost environment-friendly thermal stabilizer. The invention discloses a preparation method of a low-cost environment-friendly heat stabilizer. Comprising the following components in parts by weight: 1.8 to 2.4 parts of calcium stearate, 0.6 to 0.9 part of zinc stearate, 0.35 to 0.55 part of stearoylbenzoylmethane, 0.15 to 0.25 part of lactic acid, 0.8 to 1.5 parts of magnesium-aluminum hydrotalcite and 0.25 to 0.4 part of a trihydroxyethyl isocyanurate-silane coupling agent. All the components are based on 100 parts by weight of PVC (Polyvinyl Chloride). According to the invention, a core-shell microreactor type heat stabilizer is constructed, calcium-zinc soap is taken as a core, stearoylbenzoylmethane-lactic acid co-intercalated hydrotalcite is taken as a shell, and trihydroxyethyl isocyanurate-silane is used for double-end anchoring, so that a nanoscale coating structure is formed. The preparation method is simple in process and low in cost, and the obtained stabilizer is non-toxic, environment-friendly, excellent in performance and suitable for thermal stability modification of PVC products such as wire and cable materials.

Description

A method for preparing a low-cost, environmentally friendly heat stabilizer Technical Field

[0001] This invention relates to the field of heat stabilization modification technology for polyvinyl chloride materials, and specifically to a method for preparing a low-cost, environmentally friendly heat stabilizer. Background Technology

[0002] With increasingly stringent environmental regulations, traditional lead-containing salt stabilizers are gradually being replaced by calcium-zinc composite stabilizers that do not contain heavy metals. However, existing calcium-zinc stabilizers still have some problems that need to be solved in their application. One prominent problem is the "zinc burning" phenomenon, which is the phenomenon that the ZnCl2 produced when the stabilizer is performing its stabilizing function triggers a violent catalytic degradation of PVC. Existing technologies usually choose to add an appropriate amount of β-diketone auxiliary stabilizer to chelate ZnCl2 to reduce its activity, or add acid scavengers, such as layered dihydroxy compounds (LDH) of hydrotalcite type, to improve the thermal stability time. For example, CN120271895A discloses a PVC stabilizer for ultra-thin-wall automotive wires and its preparation method. It adds calcium-zinc composite metal soap, LDH, β-diketone compound, hindered phenolic antioxidant, phosphite antioxidant, lubricant, ultraviolet absorber, coupling agent, calcined clay and filler into a high-speed mixer for thorough mixing, and then transfers it to a twin-screw extruder for extrusion granulation to obtain the final product. However, the LDH and calcium-zinc components are not sufficiently dispersed and in close contact, making it difficult to achieve the maximum synergistic effect.

[0003] Another technical challenge is the migration and precipitation of stabilizers. Conventional stabilizers and additives in PVC products may gradually migrate to the surface over time and with thermal aging, forming blooms or precipitation. This not only affects the transparency of the product's appearance but also reduces performance and poses safety hazards. This is especially true in flexible PVC products such as cable materials that require high insulation and high stability. Adding large amounts of plasticizers and organic additives to calcium-zinc stabilizer systems leads to easy migration. For example, CN120775323A discloses a PVC composite material and its preparation method, which includes the following components by weight: 70-80 parts PVC resin, 2-5 parts heat stabilizer, 0.1-0.4 parts lubricant, 10-20 parts light-blocking agent, and 55-75 parts plasticizer. The plasticizer component is much larger than the heat stabilizer. Furthermore, calcium-zinc composite stabilizers lack designs that anchor stabilizer molecules to the PVC chain; most are still physical mixtures, thus the migration problem persists.

[0004] In summary, how to innovate a new method for preparing calcium-zinc heat stabilizers so that the heat stabilizers can have the dual functions of delaying zinc burning and reducing heat stabilizer migration, thereby improving the thermal stability of PVC products, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a low-cost and environmentally friendly method for preparing a heat stabilizer, so as to solve the technical problems in the prior art such as excessively rapid zinc burning, early blackening and embrittlement of cable materials, serious stabilizer migration, and excessive thermal elongation at 90°C.

[0006] The specific technical solution is as follows: A method for preparing a low-cost and environmentally friendly heat stabilizer, wherein the heat stabilizer comprises: 1.8-2.4 parts calcium stearate, 0.6-0.9 parts zinc stearate, 0.35-0.55 parts stearoylbenzoylmethane (SBM), 0.15-0.25 parts lactic acid, 0.8-1.5 parts magnesium aluminum hydrotalcite (MgAl-LDH), and 0.25-0.4 parts trihydroxyethyl isocyanurate (THEIC)-silane coupling agent; each component is in parts by weight, based on 100 parts PVC.

[0007] Furthermore, the calcium stearate (1.8-2.4 parts) and zinc stearate (0.6-0.9 parts) serve as the main stabilizer and component, namely the calcium-zinc soap core, which in situ constructs an inorganic shell containing synergistic stabilizing components on its exterior.

[0008] Furthermore, the inorganic shell is a sol prepared from the magnesium aluminum hydrotalcite, in which SBM and lactate anions are co-inserted and subjected to high-speed shearing, so that the LDH sheets are uniformly coated and tightly adhered to the surface of the calcium zinc soap particles, forming stable core-shell structured particles.

[0009] Furthermore, the core-shell structured particles are heated to 180°C, mixed at a constant temperature for 5 minutes under intensive mixing conditions, and then rapidly cooled and pulverized to obtain modified calcium-zinc stabilizer powder.

[0010] Further, the modified calcium-zinc stabilizer powder is then mixed with THEIC-silane coupling agent and reacted at 150°C for 3 minutes. The THEIC-silane coupling agent condenses with the hydroxyl groups on the LDH surface to form a coating layer.

[0011] A method for preparing a low-cost, environmentally friendly heat stabilizer includes the following steps: S1: Calcium stearate and zinc stearate are added to a 1L internal mixer, protected by nitrogen gas at 0.05Mpa, and melted at 130℃ for 5 minutes at a speed of 50rpm to obtain a homogeneous core melt, namely calcium-zinc soap core; SBM-lactic acid co-intercalated MgAl-LDH sol is prepared by dispersing SBM, lactic acid, and LDH in 2 parts of deionized water, and treating the solution with a 20kHz ultrasonic probe pulse at 25℃ for 30 minutes until the solution becomes transparent, thus obtaining a completely exfoliated SBM-lactic acid co-intercalated MgAl-LDH sol.

[0012] S2: Keep the internal mixer at 130℃, and spray the SBM-lactic acid co-intercalated MgAl-LDH sol evenly into the melt through a peristaltic pump nozzle with a diameter of 1.0mm. At the same time, increase the speed to 80rpm and shear at high speed for 3 minutes. Under nitrogen sealing, complete the in-situ coating of calcium zinc soap with LDH sheets to form 50~80nm core-shell particles.

[0013] S3: After heating, reduce the speed to 40 rpm, add 0.3 parts of THEIC-silane coupling agent, keep the reaction at a constant temperature, and in the last minute, evacuate to -0.085 MPa to remove moisture and free acid, so that the silane can simultaneously bond to the LDH surface and the PVC nucleophilic sites, and the melt becomes viscous and free of bubbles.

[0014] S4: The melt is cooled to 40°C within 20 seconds by circulating water with a 10°C coolant belt, then fed into a hammer crusher and pulverized through a screen to obtain a light yellow powder. This powder is then vacuum-sealed in aluminum foil bags with a moisture content of ≤0.3%, yielding the final product: the core-shell delayed-release zinc heat stabilizer.

[0015] Furthermore, the ratio of calcium stearate and zinc stearate in S1 is 2:1 to 4:1.

[0016] Furthermore, the peristaltic pump described in S2 has a rate of 2~20 mL·min. -1 .

[0017] Furthermore, the temperature rises to 140~160℃ in S3, and the isothermal reaction lasts for 2~5 minutes.

[0018] Furthermore, the screen pulverizer described in S4 has a screen aperture of 0.8~3mm.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) Delaying zinc burning and improving thermal stability: PVC releases HCl in the initial thermal decomposition stage, which reacts with the Zn of zinc stearate. 2+ The reaction generates ZnCl2, which catalyzes the further formation of HCl, initiating zinc combustion. Meanwhile, the β-diketone oxygen atom of the SBM can react with Zn in advance. 2+ Perform reversible coordination equilibrium, and place Zn 2+ The release of the heat stabilizer is delayed until after 180°C, thus extending the thermal stability time. Tests show that compared with existing ordinary calcium-zinc stabilizers, the static thermal stability time of PVC with the addition of the heat stabilizer prepared in this invention is extended by more than 50%, and the thermal stability time at 200°C is increased from 62.2 minutes to more than 95 minutes, significantly improving long-term thermal aging performance.

[0020] (2) Constructing an organic-inorganic integrated structure for synergistic stabilization: Through high-speed shearing, the calcium-zinc soap core forms nanoscale core-shell composite particles with inorganic LDH, SBM, and other components. The inorganic LDH shell tightly surrounds the calcium-zinc soap core, which on the one hand rapidly neutralizes and absorbs the HCl released during the initial thermal decomposition stage of PVC, improving the thermal stability of PVC in the middle and later stages; on the other hand, the Zn provided by zinc stearate... 2+ The synergistic reaction between LDH and SBM-lactic acid co-intercalated can delay PVC coloring. The heat stabilizer is fixed within the LDH sol layers during the initial reaction phase, thus fully leveraging the synergistic stabilizing effect between components and preventing stabilizer failure due to premature reaction, as is common in traditional physical mixing.

[0021] (3) Double-ended covalent anchoring with virtually no visible precipitation on the surface: Untreated nanoparticles have high surface energy and are prone to aggregation, making it impossible to achieve uniform nanoscale dispersion in PVC resin. This invention, through the introduction of THEIC-silane coupling agent, reduces the surface energy of the stabilizer particles, enabling them to chemically bond with the PVC chain, thereby greatly reducing the possibility of heat stabilizer migration to the product surface under high temperature and high humidity conditions. In an 80℃ migration rate test, the migration rate of the stabilizer in this invention was reduced to below 0.8%, far lower than the migration rate of over 2% for general calcium-zinc stabilizers; in a 90℃ heat extension test, the elongation rate of PVC products containing the stabilizer in this invention was ≤28%, meeting and exceeding the standard requirements of GB / T 8815-2008 "Soft Polyvinyl Chloride Plastics for Wires and Cables" for cable materials. No oil stains are released during long-term use of the products, maintaining stable appearance and electrical properties.

[0022] (4) Green, environmentally friendly and economical: The raw materials used in this invention are all non-toxic and environmentally friendly additives, such as calcium zinc soap, lactic acid, organic diketones, and hydrotalcite. They do not contain heavy metals such as lead and cadmium, nor do they use expensive and toxic components such as organotin. The preparation process has low energy consumption and a simple process flow, making it suitable for industrial-scale production. Due to the significant performance improvement, the dosage can be reduced, resulting in lower overall costs and significant economic benefits and application prospects. Attached Figure Description

[0023] Figure 1 is a flowchart of the preparation method of a low-cost and environmentally friendly heat stabilizer according to the present invention.

[0024] Figure 2 is a structural diagram of the core-shell microreactor in a low-cost, environmentally friendly heat stabilizer of the present invention.

[0025] Figure 3 is a comparison of the experimental results of Congo red at 200℃, thermal extension at 90℃, and migration at 80℃ in Experiment Example 1 of the present invention. Detailed Implementation

[0026] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0027] The technical solution designed by this invention to solve existing problems includes the following key points: 1. Core-shell microreactor structure. The core of this invention lies in constructing a core-shell microreactor structure, upgrading the traditional calcium zinc soap and LDH from simple physical mixing to in-situ coating. Conventional methods pursue rapid neutralization of HCl, resulting in Zn... 2+ In the early stages of processing, zinc is largely consumed, leaving behind potential problems such as zinc deficiency, color abrupt changes, and torque spikes in the later stages; however, the core-shell microreactor prepared in this invention utilizes Zn... 2+ Isolate it from PVC to prevent zinc burning during the initial processing stage; at the same time, the β-diketone group of SBM reacts with Zn. 2+ Dynamic coordination allows for slow dissociation only when the temperature rises above 180°C, providing a 10-30 minute safety window for subsequent extrusion and granulation, significantly extending continuous production time and reducing waste.

[0028] 2. After the THEIC-silane coupling agent completes the double-end anchoring coating, this invention further introduces THEIC-silane coupling agent for double-end anchoring, which is key to reducing migration and improving aging performance. The triazine ring and hydroxyethyl group in the THEIC molecule can pre-condense with the epoxy group of the silane to generate a coupling with a trimethoxysilane at one end and a triazine ring at the other end. During the 150℃ internal mixing stage, the silane end condenses with the hydroxyl group on the LDH surface, while the triazine end undergoes nucleophilic substitution with the allyl chloride of PVC, thereby anchoring the stabilizer to the resin chain. The macroscopic effect is as follows: the 90℃ heat elongation decreases from 54% in the physical blend to 26%, and the 80℃ migration decreases from 2.3% to 0.7%, meeting the 60℃ cable standard. This anchoring step requires no additional solvent and is completed in the same internal mixing chamber as the previous melt coating, achieving process integration and combining environmental protection with scale-up feasibility.

[0029] 3. Unlike the traditional passive anti-burn approach of adding calcium soap and supplementing phosphite, the one-step melting method of this invention actively controls Zn through nanoscale core-shell design. 2+The release rhythm allows for a reduction in the amount of heat stabilizer added without increasing the total stabilizer dosage, while still achieving a longer heat stabilization time, directly reducing formulation costs by 18-25%. Simultaneously, the one-step melting method eliminates the need for organic solvents, and the pulverized heat stabilizer powder can be directly added to existing cable material extrusion lines without equipment modifications. In summary, this solution simultaneously addresses three major pain points: rapid zinc burning, high precipitation, and poor aging, providing a new generation of heat stabilization technology for 60℃-grade environmentally friendly PVC cable materials that is lead-free, has low migration, and offers high continuous production capability.

[0030] Example 1, Table 1: Raw Material Information

[0031] A method for preparing a low-cost, environmentally friendly heat stabilizer includes the following steps: S1: 2.1 parts calcium stearate and 0.7 parts zinc stearate are added to a 1L internal mixer, protected by 0.05Mpa nitrogen gas, and melted at 130℃ at 50rpm for 5 minutes to obtain a homogeneous core melt, namely calcium-zinc soap core; SBM-lactic acid co-intercalated MgAl-LDH sol is prepared by dispersing 0.52 parts SBM, 0.23 parts lactic acid, and 1.0 parts LDH in 2 parts deionized water, and treating with a 20kHz ultrasonic probe pulse at 25℃ for 30 minutes until the solution becomes transparent, thus obtaining a completely exfoliated SBM-lactic acid co-intercalated MgAl-LDH sol.

[0032] S2: Maintain the internal mixer at 130℃, and dispense 10 mL / min through a nozzle with a diameter of 1.0 mm. -1 The SBM-lactic acid co-intercalated MgAl-LDH sol is uniformly sprayed into the melt at a speed of 80 rpm, and then sheared at high speed for 3 minutes. Under nitrogen sealing, the in-situ coating of calcium zinc soap with LDH sheets is completed, forming 50~80nm core-shell particles.

[0033] S3: Heat to 150℃, reduce speed to 40rpm, add 0.3 parts of THEIC-silane coupling agent, react at constant temperature for 3 minutes, and in the last minute, evacuate to -0.085Mpa to remove moisture and free acid, so that silane can simultaneously bond to the LDH surface and the PVC nucleophilic sites, and the melt becomes viscous and free of bubbles.

[0034] S4: The melt is cooled to 40°C within 20 seconds by circulating water with a 10°C belt coolant, then fed into a hammer crusher and pulverized through a 2mm sieve to obtain a light yellow powder. This powder is then vacuum-sealed in aluminum foil bags with a moisture content of ≤0.3%, yielding the final product: the core-shell delayed-release zinc heat stabilizer.

[0035] Example 2 follows the preparation method of Example 1, except that: S1: 2.1 parts calcium stearate and 0.7 parts zinc stearate are replaced with 2.4 parts calcium stearate and 0.6 parts zinc stearate; 0.52 parts SBM and 0.23 parts lactic acid are replaced with 0.55 parts SBM and 0.25 parts lactic acid; S2: 10 mL·min -1 Replace with 20 mL·min -1 S3: Heating to 150℃ is replaced with heating to 160℃; constant temperature reaction for 3 minutes is replaced with constant temperature reaction for 5 minutes; 0.3 parts THEIC-silane coupling agent is replaced with 0.4 parts THEIC-silane coupling agent; S4: crushing through a 2mm sieve is replaced with crushing through a 3mm sieve; all other steps are the same.

[0036] Example 3 follows the preparation method of Example 1, except that: S1: 2.1 parts calcium stearate and 0.7 parts zinc stearate are replaced with 1.8 parts calcium stearate and 0.9 parts zinc stearate; 0.52 parts SBM and 0.23 parts lactic acid are replaced with 0.35 parts SBM and 0.15 parts lactic acid; S2: 10 mL·min -1 Replace with 2 mL·min -1 S3: Replacing 150℃ with 140℃; Replacing 3 minutes of constant temperature reaction with 2 minutes of constant temperature reaction; Replacing 0.3 parts of THEIC-silane coupling agent with 0.25 parts of THEIC-silane coupling agent; S4: Replacing pulverization through a 2mm sieve with pulverization through a 0.8mm sieve; All other steps are the same.

[0037] Comparative Example 1 follows the preparation method of Example 1, except that: S1 and S2: the preparation of the core-shell microreactor is omitted, and 2.1 parts of calcium stearate, 0.7 parts of zinc stearate, 0.52 parts of SBM, 0.23 parts of lactic acid, 1.0 parts of LDH and 0.3 parts of THEIC-silane coupling agent are directly mixed at 110°C for 5 minutes at high speed.

[0038] All other steps are the same.

[0039] Comparative Example 2 follows the same preparation method as Example 1, except that: S1: the preparation of SBM-lactic acid co-intercalated MgAl-LDH sol is omitted, and untreated SBM and LDH are directly mixed into the melt.

[0040] All other steps are the same.

[0041] Comparative Example 3 was prepared using the same method as Example 1, except that: S3: the step of adding THEIC-silane coupling agent was omitted.

[0042] All other steps are the same.

[0043] Experimental Example 1: 3.0 parts of the heat stabilizer powder prepared in Examples 1-3 and Comparative Examples 1-3 were mixed with 100 parts of PVC (SG-5), 50 parts of dioctyl phthalate (DOP), 0.6 parts of polyethylene wax, and 0.4 parts of monoglyceride at high speed. The mixture was then melted and plasticized in a two-roll mill and finally cooled at room temperature. The following results were obtained: (1) 200℃ Congo Red: The sample was cut into 40×40mm pieces, referring to GB / T 2917.1-2002 "Determination of the release of hydrogen chloride and any other acidic products at high temperature from blends and products mainly composed of vinyl chloride homopolymers and copolymers—Congo red method". A thin copper wire is passed through the corner of the test strip and suspended in the middle of a 250mL beaker or test tube, with the bottom of the strip ≥10mm from the bottom of the beaker. A 5mm wide Congo red test paper ring is hung on the copper wire, with the lower edge 50mm from the top of the strip. The glycerol bath is set at 200±2℃, with the liquid level 20mm above the test paper. The stopwatch is started the instant the test paper is placed in the bath. The test is stopped immediately when the lower edge of the test paper begins to turn blue. The time is recorded. Two more test strips of the same sample are then tested separately. The difference is ≤10%. The average of the three tests is the Congo red time at 200℃.

[0044] (2) 90℃ heat extension: Cut the sample into 120×15mm dumbbell strips. Refer to GB / T 2951.21-2017 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Cables Part 21: Test Methods for Elastomer Mixtures - Heat Extension Test", hang the dumbbell test piece in a 90℃ oven, add weight to the bottom, measure the elongation after 15 minutes, and then take two pieces of the same sample to conduct the test separately. The difference is ≤2%. Take the average of 3 tests to obtain the 90℃ heat extension.

[0045] (3) Migration at 80℃: Cut the sample into 30×30mm pieces and record the weight as m0. Refer to GB / T 8815-2008 "Soft Polyvinyl Chloride Plastics for Wires and Cables". Clamp the PVC test piece with a quantitative filter paper of mass m1. After 80℃ for 24 hours, weigh the filter paper and record its weight as m2. This is the migration amount. The formula is migration amount (%) = (m2-m1) / m0×100%. Take two pieces of the same sample and conduct experiments to determine the migration amount. The difference is ≤0.2%. Take the average of the three measurements to determine the migration amount at 80℃.

[0046] Table 2 Comparison of experimental results of Examples 1-3 and Comparative Examples 1-3

[0047] The experimental results of Examples 1-3 and Comparative Examples 1-3 are shown in Table 2 and Figure 3. The heat stabilizer prepared by the present invention simultaneously meets the requirements of ≥100 min at 200℃ Congo Red, ≤30% thermal extension at 90℃, and ≤0.8% migration at 80℃. Moreover, the processing load, energy consumption and dust level are all within the equipment's load-bearing range, so it is confirmed as the optimal implementation point.

[0048] Example 2 uses 20 mL·min-1 The injection speed leads to a thinner shell layer and reduced uniformity, requiring additional calcium and zinc and a high proportion of SBM to restore performance, thus increasing raw material costs. Anchoring at 160℃ increases the yellowing index of PVC, requiring the application of color-correcting powder to transparent materials, increasing hidden costs. While 3mm coarse powder increases production speed, the average particle size of the pulverized particles increases, leading to increased light scattering intensity in high-transparency cable materials, resulting in increased haze and decreased transparency, resulting in negative marginal returns. Although Example 3 appears similar to Example 1 in terms of data, this scheme increases the proportion of zinc stearate to improve initial stability and relies on a 0.8mm ultrafine pulverization process to forcibly improve its dispersibility, resulting in increased dust and poor economics for continuous production. Furthermore, the ultrafine powder is hygroscopic, increasing moisture content by approximately 0.2% after 48 hours of storage, requiring additional drying costs. Therefore, considering performance, energy consumption, production speed, and cost, Examples 2 and 3 are not optimal implementation points.

[0049] Due to the lack of key technologies, the overall performance of Comparative Examples 1-3 was reduced to varying degrees compared to the Examples. Comparative Example 1 omitted the core-shell structure and performed physical blending of SBM and Zn. 2+ In instantaneous contact at 200℃, Congo red reacted in only 62.2 minutes, 40.3 minutes shorter than in Example 1. Thermal extension (54.4%) and migration (2.3%) both exceeded the limits, directly proving that without shell coating, the delay effect is zero. Comparative Example 2 lacked SBM-lactic acid co-intercalation, the LDH sheets were not peeled off, the shell was discontinuous, and Zn... 2+ Release was advanced by approximately 20 minutes, and thermal elongation increased by 16% and migration increased by 0.8% compared to Example 1, verifying that co-intercalation peeling is a necessary condition for the formation of a dense shell; Comparative Example 3 had no THEIC-silane coupling agent anchoring, lacking the double-end bonding of THEIC-silane coupling agent, and the stabilizer was only adsorbed on the PVC surface by hydrogen bonds. The migration amount increased to 1.5% at 80°C for 24 hours, and thermal elongation increased by 9.2% compared to Example 1, confirming that covalent anchoring is a key step in reducing precipitation and improving aging at 90°C.

[0050] In summary, this invention constructs a core-shell microreactor type heat stabilizer with calcium-zinc soap as the core, SBM-lactic acid co-intercalated LDH as the shell, and then anchored at both ends with THEIC-silane coupling agent to form a nanoscale encapsulation structure. This results in a Congo red elongation time of >95 min at 200℃, thermal elongation ≤30% at 90℃, and migration ≤0.8% at 80℃, all significantly superior to the physical blending control. Furthermore, the one-step melting method is solvent-free and heavy metal-free, directly replacing the existing calcium-zinc system, providing a low-migration, highly continuous production upgrade path for 60℃-grade environmentally friendly PVC cable materials.

Claims

1. A method for preparing a low-cost, environmentally friendly heat stabilizer, characterized in that, The preparation method involves constructing a calcium-zinc soap core, a stearoylbenzoylmethane-lactic acid co-intercalated magnesium-aluminum hydrotalcite sol nanoshell, and using trihydroxyethyl isocyanurate-silane coupling agent for bi-end anchoring, thereby forming a delayed-release zinc lead-free core-shell coating structure through one-step melting.

2. The preparation method of the low-cost environmentally friendly heat stabilizer as described in claim 1, characterized in that, The process includes the following steps: S1: Calcium stearate and zinc stearate are added to a reaction vessel, protected with nitrogen, and melted at 130°C for 5 minutes to obtain a homogeneous core melt, i.e., calcium-zinc soap core; Stearoyl benzoylmethane-lactic acid co-intercalated magnesium aluminum hydrotalcite sol is prepared by dispersing stearoyl benzoylmethane, lactic acid, and hydrotalcite in deionized water and ultrasonically treating at 25°C for 30 minutes to obtain a completely exfoliated stearoyl benzoylmethane-lactic acid co-intercalated magnesium aluminum hydrotalcite sol; S2: The reaction vessel is kept at 130°C, and stearoyl benzoylmethane is added to a reaction vessel... Alkyl-lactic acid co-intercalated magnesium aluminum hydrotalcite sol is uniformly sprayed into the melt, and high-speed shearing is performed for 3 minutes. Under nitrogen sealing, the hydrotalcite lamellae complete the in-situ coating of calcium zinc soap, forming core-shell particles; S3: After heating, the speed is reduced, and then trihydroxyethyl isocyanurate-silane coupling agent is added. The reaction is carried out at a constant temperature to remove moisture and free acid; S4: The melt is cooled to 40°C with a coolant, and then sent to a crusher to be pulverized through a sieve to obtain a light yellow powder. It is then vacuum-sealed in an aluminum foil bag with a moisture content ≤0.3%, which is the final product, the core-shell delayed-release zinc heat stabilizer.

3. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 1, characterized in that, The heat stabilizer comprises the following components by weight: 1.8-2.4 parts calcium stearate, 0.6-0.9 parts zinc stearate, 0.35-0.55 parts stearoylbenzoylmethane, 0.15-0.25 parts lactic acid, 0.8-1.5 parts magnesium aluminum hydrotalcite, and 0.25-0.4 parts trihydroxyethyl isocyanurate-silane coupling agent; each component is based on parts by weight, with 100 parts PVC as the reference.

4. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, The calcium stearate and zinc stearate in S1 are in a ratio of 2:1 to 4:

1.

5. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, S2 describes the uniform spraying of stearoylbenzoylmethane-lactic acid co-intercalated magnesium aluminum hydrotalcite sol into the melt at a spraying rate of 2~20 mL·min. -1 .

6. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, The core-shell particles described in S2 have a size of 50~80nm.

7. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, The temperature rise described in S3 is increased to 140~160℃, and the isothermal reaction takes 2~5 minutes.

8. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, The isothermal reaction described in S3, which removes moisture and free acid, requires evacuation to -0.085 MPa during the last minute of the isothermal reaction.

9. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, The sieve crusher described in S4 has a sieve aperture of 0.8~3mm.

10. The method for preparing a low-cost, environmentally friendly heat stabilizer as described in claim 2, characterized in that, The core-shell delayed-release zinc heat stabilizer product described in S4 has a Congo red time of >95 min at 200℃, a thermal elongation of ≤30% at 90℃, and a migration of ≤0.8% at 80℃.

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