Environment-friendly organic tin stabilizer for low-odor PVC (polyvinyl chloride) and preparation process of environment-friendly organic tin stabilizer

Abstract

The invention provides an environment-friendly organic tin stabilizer for low-odor PVC (polyvinyl chloride) and a preparation process, and relates to the technical field of material processing.The stabilizer comprises 38%-52% of environment-friendly organic tin main body, 10%-20% of synergistic auxiliary stabilizer system, 10%-20% of molecular sieve controlled release type odor inhibitor, 10%-20% of interface orientation dispersing agent and 10%-20% of multi-stage antioxidant system. The adding proportion of the synergistic auxiliary stabilizer system is 22%-34%, the molecular sieve controlled release type odor inhibitor accounts for 10%-16% of the total mass of the stabilizer, and the interface orientation dispersant accounts for 6%-11% of the total mass of the stabilizer. And uniform dispersion and controlled release of the odor inhibitor in the stabilizer are realized by adopting modes of surface modified zeolite powder, interlamellar spacing controlled montmorillonite or embedded beta-cyclodextrin and the like.

Description

Technical Field

[0001] This invention relates to the field of materials processing technology, specifically to an environmentally friendly organotin stabilizer for low-odor PVC and its preparation process. Background Technology

[0002] As the plastics industry moves towards high performance, environmental friendliness, and low odor, polyvinyl chloride (PVC) materials are increasingly widely used in construction, home appliances, wires and cables, and daily necessities. To ensure the thermal stability of PVC during processing and use, organotin stabilizers are typically added. However, traditional organotin stabilizers, mainly polyalkyltin and alkoxytin, have certain limitations in their application with PVC.

[0003] Existing low-odor, environmentally friendly organotin stabilizers for PVC mainly exhibit the following characteristics: some use a single organotin compound, or are simply mixed with a calcium-zinc composite system; they are prone to odor volatilization during processing, making it difficult to effectively control odor release; simultaneously, to improve thermal stability, they rely on high levels of organometallic compounds, which often leads to poor dispersibility and high melt viscosity, affecting the processing performance and appearance uniformity of PVC products. Furthermore, some stabilizers lack multi-level protection against oxidation and photoaging, easily causing discoloration or performance degradation of PVC products with long-term use.

[0004] However, existing low-odor PVC organotin stabilizers still have the following key technical problems in practical applications: Insufficient odor control: The odor inhibitors in existing stabilizers are unevenly dispersed or have uncontrollable release rates, resulting in obvious odors in PVC products during processing and use, which affects the indoor environment and user experience; Melt dispersion and viscosity control are difficult: single or simple compound organotin systems are prone to forming heterogeneous structures in the molten state, resulting in uneven dispersion of stabilizers, high apparent viscosity or large fluctuations, thus affecting the fluidity and processing uniformity of PVC. Insufficient antioxidant and photo-aging protection: Existing stabilizers mostly rely on a single antioxidant component and lack a multi-level antioxidant system and UV absorption regulation. PVC products are prone to discoloration, aging, or performance degradation under long-term high temperature, light exposure, or processing conditions, reducing the durability and service life of the products.

[0005] Therefore, a low-odor, environmentally friendly organotin stabilizer for PVC and its preparation process are needed to solve the above problems. Summary of the Invention

[0006] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an environmentally friendly organotin stabilizer for low-odor PVC and its preparation process, thus solving the problems mentioned in the background technology.

[0007] Technical solution To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly organotin stabilizer for low-odor PVC, comprising a stabilizer, wherein the stabilizer includes an environmentally friendly organotin matrix, a synergistic auxiliary stabilizer system, a molecular sieve controlled-release odor inhibitor, an interfacial orientation dispersant, and a multi-stage antioxidant system. The environmentally friendly organotin matrix is ​​added at a ratio of 38% to 52%, the synergistic auxiliary stabilizer system is added at a ratio of 22% to 34%, the molecular sieve controlled-release odor inhibitor accounts for 10% to 16% of the total mass of the stabilizer, the interfacial orientation dispersant accounts for 6% to 11% of the total mass of the stabilizer, and the multi-stage antioxidant system accounts for 3% to 7% of the total mass of the stabilizer. Furthermore, each component forms a continuously distributed composite stable phase within the stabilizer.

[0008] Preferably, the environmentally friendly organotin host is a composite organotin system formed by at least two of methyl mercaptan, butyl mercaptan, and octyl mercaptan in a gradient mass ratio, wherein the environmentally friendly organotin host accounts for 44% to 49% of the total mass of the stabilizer, the tin content in the environmentally friendly organotin host is 19% to 21% by mass, and the organotin with different alkyl chain lengths in the composite organotin system exhibits a heterogeneous micro-distribution structure in the molten state.

[0009] Preferably, the synergistic auxiliary stabilizer system includes a calcium-zinc composite stabilizer, a fatty acid metal salt, and a polyhydroxy alcohol compound, wherein the calcium-zinc composite stabilizer, the fatty acid metal salt, and the polyhydroxy alcohol compound form a stable ternary structure in a certain mass ratio, the synergistic auxiliary stabilizer system accounts for 27% to 31% of the total stabilizer mass, and its overall melt transition temperature range is 58°C to 72°C.

[0010] Preferably, the molecular sieve controlled-release odor inhibitor is at least one of surface-organically modified zeolite powder, interlayer spacing-controlled montmorillonite, or encapsulated β-cyclodextrin, and the odor inhibitor accounts for 12% to 15% of the total mass of the stabilizer, and the specific surface area of ​​the odor inhibitor is 90 m² / g to 140 m² / g; the interfacial oriented dispersant is a composite dispersion system formed by polyethylene glycol compounds and fatty acid ester compounds, and the interfacial oriented dispersant accounts for 7% to 10% of the total mass of the stabilizer.

[0011] Preferably, the multi-level antioxidant system includes a main antioxidant unit formed by hindered phenolic antioxidants and phosphite antioxidants, and the stabilizer further includes a UV absorption regulating component, which is a benzotriazole UV absorber or a benzophenone UV absorber. The UV absorption regulating component accounts for 3% to 6% of the total mass of the stabilizer, and the antioxidant system and the UV absorption regulating component form an interleaved distribution structure in the molten state.

[0012] Preferably, the mass ratio of the environmentally friendly organotin host to the synergistic auxiliary stabilizer system is 1.3:1 to 1.7:1, the mass ratio of the molecular sieve controlled-release odor inhibitor to the interfacial oriented dispersant is 1.6:1 to 2.1:1, the overall melting point of the stabilizer is controlled between 48°C and 63°C, and its apparent viscosity in the molten state is between 9 mPa·s and 18 mPa·s.

[0013] Preferably, the preparation process includes the following steps: SP1: Prepare an environmentally friendly organotin substrate, a synergistic auxiliary stabilizer system, a molecular sieve controlled-release odor inhibitor, an interfacial orientation dispersant, and a multi-stage antioxidant system, with each raw material having a purity of not less than 99.0%; SP2: In a closed reactor, melt-complicate the environmentally friendly organotin substrate and the synergistic auxiliary stabilizer system, controlling the temperature at 62°C to 72°C; SP3: Introduce the molecular sieve controlled-release odor inhibitor and the multi-stage antioxidant system into the melt system obtained in SP2 in a segmented manner; SP4: Add the interfacial orientation dispersant and continuously shear-mix; SP5: Perform vacuum devolatilization on the resulting mixture; SP6: After devolatilization, cool, homogenize, and granulate.

[0014] Preferably, SP2 is carried out under inert gas protection conditions, the inert gas being nitrogen or helium, the stirring speed being 320 rpm to 380 rpm, the mixing time being 22 minutes to 28 minutes, and a metal complex passivating agent is introduced during the mixing process to limit the migration of metal ions.

[0015] Preferably, in SP3, the molecular sieve controlled-release odor inhibitor is dehydrated and activated before being added. The activation conditions are 100°C to 110°C for 2 to 3 hours. The odor inhibitor is added in multiple batches, with each batch not exceeding 18% of the total amount. Electromagnetic wave-assisted dispersion is used between batches at a frequency of 2450MHz to 2480MHz for 8 to 12 minutes.

[0016] Preferably, in SP4, the interfacial orientation dispersant is introduced via micro-atomization, with an atomized particle size of 1.2 micrometers to 2.8 micrometers, and the stirring speed is increased to 480 rpm to 540 rpm; in SP5, the devaporization pressure is -0.075 MPa to -0.065 MPa, the temperature is 82°C to 88°C, and after devaporization, high-pressure homogenization is performed at a pressure of 75 MPa to 95 MPa, with 3 to 5 cycles, followed by constant-temperature curing at 62°C to 68°C for 2 to 3 hours.

[0017] Beneficial effects This invention provides an environmentally friendly organotin stabilizer for low-odor PVC and its preparation process. It has the following beneficial effects: 1. This invention achieves uniform dispersion and controlled release of the odor inhibitor in the stabilizer by introducing a molecular sieve controlled-release odor inhibitor and employing methods such as surface-modified zeolite powder, interlayer spacing-controlled montmorillonite, or encapsulated β-cyclodextrin. Through multi-batch, staged addition and electromagnetic wave-assisted dispersion technology, the stabilizer can continuously and effectively suppress odor volatilization during processing and use, significantly reducing the odor release of PVC products and improving the comfort of the indoor environment and user experience.

[0018] 2. This invention achieves a uniform distribution and heterogeneous micro-distribution structure of the stabilizer in the molten state through a rational ratio of environmentally friendly organotin matrix and synergistic auxiliary stabilizer system, a gradient distribution composite organotin design, and the micro-atomization introduction of an interface-oriented dispersant. This controls the overall melting point (48℃~63℃) and apparent melt viscosity (9~18 mPa·s) of the stabilizer, improving the melt flowability and processing uniformity of PVC, and significantly enhancing the appearance uniformity and processing performance of the finished product.

[0019] 3. This invention constructs a multi-level antioxidant system composed of hindered phenols and phosphites, combined with UV absorption regulating components (benzotriazoles or benzophenones), forming an interwoven distribution structure in the molten state to achieve long-lasting antioxidant and photo-aging protection for PVC products. This design effectively delays discoloration and performance degradation of PVC under high temperature, light exposure, and long-term use conditions, improving product durability and service life, and meeting the application requirements of high-performance, low-odor PVC products. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating the formulation of the present invention; Figure 2 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific Implementation Example 1: like Figures 1 to 2 As shown, an environmentally friendly organotin stabilizer for low-odor PVC is provided. The environmentally friendly organotin stabilizer for low-odor PVC is composed of an environmentally friendly organotin main body, a synergistic auxiliary stabilizer system, a molecular sieve controlled-release odor inhibitor, an interfacial orientation dispersant, and a multi-level antioxidant system. The components are compounded in a set ratio to form a stabilizer composition.

[0023] The environmentally friendly organotin matrix is ​​a composite system of methyl mercaptan and octyl mercaptan, which are mixed in a gradient mass ratio and used together as the main stabilizing component in the stabilizer. The proportion of the environmentally friendly organotin matrix in the stabilizer is controlled between 44% and 49%, and its tin element mass content is controlled between 19% and 21%. Organotins with different alkyl chain lengths maintain their respective structural characteristics during the melt mixing process, forming a heterogeneous micro-distribution state within the stabilizer to meet the needs of subsequent compounding.

[0024] The synergistic auxiliary stabilizer system consists of a calcium-zinc composite stabilizer, a fatty acid metal salt, and a polyhydroxy alcohol compound. The calcium-zinc composite stabilizer is a conventional industrial-grade calcium-zinc salt compound, the fatty acid metal salt is magnesium stearate, and the polyhydroxy alcohol compound is pentaerythritol. These three components are combined in a specific mass ratio to form a stable ternary synergistic structure. The synergistic auxiliary stabilizer system accounts for 27% to 31% of the stabilizer, and its overall melt transition temperature is within the range of 58℃ to 72℃.

[0025] The molecular sieve controlled-release odor inhibitor uses a composite system of surface-modified organic zeolite powder and encapsulated β-cyclodextrin. The zeolite powder is surface-treated with organosilanes, and the β-cyclodextrin is introduced through encapsulation. The proportion of the molecular sieve controlled-release odor inhibitor in the stabilizer is controlled at 12% to 15%, and its specific surface area is in the range of 90 m² / g to 140 m² / g.

[0026] The interfacial orientation dispersant is formed by combining polyethylene glycol compounds and fatty acid ester compounds. The polyethylene glycol is selected with a molecular weight of 400 to 600, and the fatty acid ester compound is selected as glyceryl stearate. The two are combined in a set ratio and used as an interfacial orientation dispersant. Its addition ratio in the stabilizer is 7% to 10%.

[0027] The multi-level antioxidant system consists of hindered phenolic antioxidants and phosphite antioxidants, which, when combined, form the main antioxidant unit. Simultaneously, a UV absorption modifier, specifically a benzotriazole UV absorber, is added to the stabilizer. The total proportion of the multi-level antioxidant system and the UV absorption modifier in the stabilizer is controlled between 3% and 6%, forming an interleaved distribution structure with other components in the molten state.

[0028] By combining the above components, a low-odor, environmentally friendly organotin stabilizer composition for PVC is finally obtained, in which the components form a continuously distributed composite stable phase within the stabilizer.

[0029] The following are the specific formula and proportion data: ; Specific Implementation Example 2: like Figures 1 to 2 As shown, in this embodiment, the low-odor PVC environmentally friendly organotin stabilizer is prepared according to the following steps.

[0030] SP1: Raw Material Preparation An environmentally friendly organotin base, a synergistic auxiliary stabilizer system, a molecular sieve controlled-release odor inhibitor, an interfacial orientation dispersant, and a multi-stage antioxidant system are prepared. The purity of each raw material is tested before use to ensure that its purity is not less than 99.0%, and the hygroscopic raw materials are pre-dried.

[0031] SP2: Melt blend An environmentally friendly organotin matrix and a synergistic auxiliary stabilizer system are added to a sealed reactor and melt-blended under inert gas protection conditions, wherein the inert gas is nitrogen or helium. The reactor temperature is controlled between 62°C and 72°C, the stirring speed is controlled between 320 rpm and 380 rpm, and the mixing time is between 22 minutes and 28 minutes. A metal complexing passivating agent is introduced during the mixing process to complex with the metal ions in the system.

[0032] SP3: Segmented introduction of odor inhibitors and antioxidant systems In the molten system obtained from SP2, a molecular sieve controlled-release odor inhibitor and a multi-stage antioxidant system are introduced in stages. The molecular sieve controlled-release odor inhibitor is first dehydrated and activated before addition, with activation conditions of 100°C to 110°C for 2 to 3 hours. The odor inhibitor is added in multiple batches, with each batch not exceeding 18% of the total amount. Adjacent batches are dispersed using electromagnetic wave-assisted dispersion, with the electromagnetic wave frequency ranging from 2450MHz to 2480MHz and the treatment time from 8 to 12 minutes.

[0033] SP4: Dispersant introduction and shear mixing After completing SP3, the interfacial orientation dispersant is introduced into the reaction system by micro-atomization, with the atomized particle size controlled in the range of 1.2 micrometers to 2.8 micrometers. At the same time, the stirring speed is increased to 480 rpm to 540 rpm to achieve uniform mixing in the system.

[0034] SP5: Reduced pressure devolatilization and homogenization The mixture was subjected to vacuum devolatilization, with the devolatilization pressure controlled between -0.075 MPa and -0.065 MPa, and the temperature controlled between 82°C and 88°C. After devolatilization, the material was subjected to high-pressure homogenization, with a homogenization pressure of 75 MPa to 95 MPa and a cycle number of 3 to 5 times.

[0035] SP6: Curing and Granulation The homogenized material is placed under constant temperature conditions for curing treatment. The curing temperature is controlled between 62℃ and 68℃, and the curing time is 2 to 3 hours. Then the cured material is cooled to below 30℃ and granulated by a granulator to obtain the finished product, low-odor PVC environmentally friendly organic tin stabilizer. Specific Implementation Example 3: like Figures 1 to 2 As shown, the following provides the characterization and performance testing of the finished product: This embodiment characterizes and tests the finished product of the low-odor PVC environmentally friendly organotin stabilizer prepared according to Example 2 to verify its physicochemical properties, dispersion uniformity and thermal stability.

[0037] 1. Appearance and Dispersion: The prepared stabilizer particles were examined for their appearance and dispersion using an optical microscope. The results showed that: The finished product is a light yellow, uniform granule or powder with a smooth surface and no obvious clumping or layering. When the stabilizer is added to the PVC melt in the molten state and mixed evenly, a transparent to slightly turbid molten system is obtained. No obvious phase separation is observed, indicating that the components form a continuously distributed composite stable phase in the stabilizer.

[0038] 2. Viscosity and Melting Point: Melting point test: Differential scanning calorimetry (DSC) was used to test the melt transition temperature range of the stabilizer. Results showed: The main melting point range is 48℃ to 63℃, which is consistent with the design range. The melt transition temperature of the synergistic stabilizer system is between 58℃ and 72℃, indicating that the ternary synergistic structure forms a stable composite system.

[0039] Apparent viscosity: The viscosity of the stabilizer in its molten state was measured using a rotational viscometer at a constant temperature of 80℃. The result was 10.2 mPa·s, which falls within the design range of 9–18 mPa·s. It has good fluidity and is beneficial for uniform mixing during PVC processing.

[0040] 3. Tin content and distribution: The tin content in the stabilizer was determined by atomic absorption spectrometry (AAS), and the results showed that the tin content was 19.4% by mass, which is within the design range of 19%–21%.

[0041] The distribution of organotin within the stabilizer was observed using scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS). The results showed that methyl mercaptan and octyl mercaptan formed a gradient-distributed heterogeneous microstructure with uniform tin element distribution in the micro-regions, ensuring the stability of the composite system in PVC melt.

[0042] 4. Characterization of molecular sieve controlled-release odor inhibitors: The specific surface area of ​​the molecular sieve controlled-release odor inhibitor was determined by the BET method, and the result was 115 m² / g, which is within the design range of 90–140 m² / g.

[0043] Odor release experiments (heating PVC melt to 160°C and analyzing volatile substances using gas chromatography) showed that the odor of the finished product was significantly reduced, with an odor release rate of approximately 60% compared to traditional organotin stabilizers.

[0044] 5. Analysis of interfacial orientation dispersants and composite structures: The arrangement of the interfacial orientation dispersant in the molten system was observed using transmission electron microscopy (TEM). The results showed that: Polyethylene glycol compounds and fatty acid ester compounds form a complex dispersion system with a layered or network oriented structure along the component interface, which is beneficial to improving the dispersibility of organotin and synergistic stabilizers. The multi-level antioxidant system and ultraviolet absorption regulating components are interwoven in the molten state, forming a continuous antioxidant protection network.

[0045] 6. Thermal stability test: Thermal stability of PVC mixtures: 1.5% by mass of the stabilizer from this embodiment was added to the PVC resin, and the thermal stability time (TSP) was determined using the roller method at 200°C. The results showed: The initial weightlessness time (time when PVC begins to decompose) is >280 min; The endpoint color retention time is >360 min, which is significantly better than the traditional single-component organotin system.

[0046] 7. Antioxidant and yellowing resistance: After preparation, the PVC film underwent accelerated aging testing (80℃, 65% relative humidity, UV-A 340nm illumination, 8 h / day, for 7 consecutive days). Its yellowing index (YI) was measured, and the results showed: The change in YI after 7 days was less than 3 units, indicating that the stabilizer has excellent antioxidant and yellowing resistance properties.

[0047] 8. Overall Evaluation: Based on the above tests, the finished stabilizer of Example 3 exhibits the following characteristics: It has good melt flowability, which facilitates PVC processing; odor release is significantly reduced, making it suitable for low-odor PVC applications; the organotin and synergistic auxiliary stabilizer system is evenly distributed, resulting in a stable composite structure; the multi-level antioxidant and UV absorption regulation system effectively improves thermal stability and yellowing resistance. Specific Implementation Example 4: like Figures 1 to 2 As shown, the following provides a complete quality control method for the entire process from preparation to finished product delivery to ensure batch consistency, performance stability, and compliance with industrial production requirements: 1. Raw material warehousing and pretreatment: Raw materials entering the warehouse: environmentally friendly organic tin main body, synergistic auxiliary stabilizer system, molecular sieve controlled-release odor inhibitor, interface orientation dispersant, multi-level antioxidant system and ultraviolet absorption regulation component.

[0049] Quality control measures: The purity of each raw material is not less than 99.0%, and analysis is performed using high performance liquid chromatography (HPLC) or gas chromatography (GC). The hygroscopic raw materials (such as molecular sieves, montmorillonite, and β-cyclodextrin) are dried at 100℃–110℃ for 2–3 hours. Upon receipt of raw materials, sampling tests are conducted on the moisture content, impurity elements, and specific surface area of ​​each raw material to ensure compliance with design specifications.

[0050] 2. Preparation process control: SP1: Melt blend The environmentally friendly organotin matrix and the synergistic auxiliary stabilizer system are added to a closed reactor and melt-combined under inert gas protection conditions.

[0051] Temperature control: 62℃–72℃; stirring speed: 320–380 rpm; mixing time: 22–28 minutes.

[0052] Process control: Metal complex passivating agents are introduced, metal ion migration is monitored in real time, and metal ion content is detected by atomic absorption spectroscopy to ensure that the distribution of metal ions in the stabilizer system is uniform and controlled.

[0053] SP2: Segmented introduction of molecular sieve controlled-release odor inhibitor and antioxidant system Molecular sieve controlled-release odor inhibitors are dehydrated and activated before addition, and are added in multiple batches, with each batch accounting for ≤18% of the total amount.

[0054] Electromagnetic wave-assisted dispersion (frequency 2450–2480 MHz, processing time 8–12 minutes) is used to ensure uniform distribution of odor inhibitors in the molten system.

[0055] A multi-level antioxidant system and ultraviolet absorption regulating components are introduced simultaneously, and shear mixing is used to ensure the formation of an interleaved distribution structure.

[0056] SP3: Introduction of interfacial orientation dispersant The interfacial orientation dispersant was added via micro-atomization (particle size 1.2–2.8 μm), and the stirring speed was increased to 480–540 rpm to achieve uniform dispersion within the system.

[0057] SP4: Reduced pressure devouring and high pressure homogenization Deviation conditions: -0.075 to -0.065 MPa, temperature 82–88℃, until the solvent and low-boiling components in the system are completely evaporated.

[0058] High-pressure homogenization: 75–95 MPa pressure, 3–5 cycles, to ensure particle refinement and the formation of a stable and uniform composite system.

[0059] SP5: Cooling, Curing and Granulation After homogenization, the system is aged at a constant temperature of 62–68℃ for 2–3 hours.

[0060] After maturation, the mixture is rapidly cooled to below 30°C and then granulated using a granulator to obtain the finished stabilizer granules.

[0061] 3. Full-process quality control methods Raw material quality control: incoming inspection, moisture detection, impurity element analysis, specific surface area and activity detection.

[0062] Process monitoring: Melting temperature, stirring speed, and mixing time are monitored throughout the process; metal ion migration is monitored online using atomic absorption spectroscopy; and the uniformity of odor inhibitor and dispersant distribution is verified through microscopic sampling and SEM / TEM analysis.

[0063] Intermediate product testing: Melt mixture viscosity testing (rotational viscometer) ensures a range of 9–18 mPa·s; DSC determination of melt transition temperature ensures a range of 48–63 °C; odor suppression performance testing (GC volatile component analysis).

[0064] Finished product inspection: Appearance: Uniform particles, light yellow, no layering; Tin content (AAS): 19–21%; Odor release test: Volatile substances decreased by ≥60%; Thermal stability: TSP ≥280 min, endpoint color retention time ≥360 min; Antioxidant and yellowing resistance: Yellowing index (YI) change of PVC film <3 after 7 days.

[0065] Batch Records and Traceability: The entire process of recording each batch of raw materials, process parameters, and test results is documented to create a traceability file; non-conforming batches are isolated, the causes are analyzed, and corrective measures are taken.

[0066] Factory Standards: Only products that meet the above-mentioned requirements for all test indicators can be shipped from the factory; samples are randomly selected for retesting before shipment to ensure batch consistency.

[0067] 4. General Explanation: This embodiment establishes a complete preparation process from raw material warehousing, melt compounding, segmented component introduction, shear mixing, vacuum devolatilization, high-pressure homogenization, cooling and curing to granulation. Combined with multi-stage quality control measures, it can ensure the stable performance, batch consistency, and industrial production feasibility of the environmentally friendly organotin stabilizer for low-odor PVC. Specific Implementation Example 5: like Figures 1 to 2 As shown, the following is a comparative experimental design: 1. Experimental objective: This embodiment verifies the advantages of the low-odor, environmentally friendly organotin stabilizer for PVC of the present invention in the following aspects through a comparative experiment: Odor suppression effect; Thermal stability and resistance to yellowing; Melt processing fluidity; Compare the performance differences between traditional single-component organotin and conventional calcium-zinc composite stabilizers.

[0069] 2. Experimental materials: Experimental group (stabilizer of the present invention): environmentally friendly organotin stabilizer for low-odor PVC prepared in Example 1.

[0070] Comparative Group 1: Single-component methyltin stabilizer, with an addition amount comparable to that of the environmentally friendly organotin main component in the experimental group.

[0071] Comparison Group 2: Conventional calcium-zinc composite stabilizer, with an addition amount comparable to the synergistic auxiliary stabilizer system in the experimental group.

[0072] PVC resin: General-purpose polyvinyl chloride resin with the same molecular weight.

[0073] Other auxiliary additives: Lubricants and processing aids are added in the same proportion.

[0074] 3. Experimental Design: Sample preparation: Each stabilizer was added to the PVC resin separately, with a total stabilizer addition of 1.5% (mass fraction). After being mixed evenly, the mixture was melt-blended using a hot mixer to produce PVC sheets or test strips.

[0075] Experimental conditions: Thermal stability: 200℃ roller method, recording the initial weight loss time and the final color retention time (TSP).

[0076] Odor release: The amount of volatile organic compounds released was analyzed by gas chromatography (GC) after heating the PVC melt to 160°C.

[0077] Yellowing resistance: The PVC sheet was subjected to accelerated aging test (80℃, relative humidity 65%, UV-A 340 nm light irradiation, for 7 consecutive days) to determine the yellowing index (YI).

[0078] Melt flowability: Melt viscosity was measured at a constant temperature of 80°C (rotational viscometer).

[0079] 4. Experimental Results and Analysis: ; Odor suppression effect: The odor release in the experimental group was significantly lower than that of the single-component methyltin and calcium-zinc composite stabilizer, with reductions of approximately 60% and 45%, respectively, verifying the superiority of the molecular sieve controlled-release odor inhibitor and interfacial oriented dispersant composite system.

[0080] Thermal stability: The TSP of the experimental group was significantly prolonged, increasing by about 170% compared to control group 1 and by about 40% compared to control group 2, indicating that the composite organotin and synergistic auxiliary stabilizer system has a synergistic enhancing effect.

[0081] Yellowing resistance: The experimental group showed the smallest change in yellowing index, indicating that the multi-level antioxidant system and UV absorption regulating components effectively inhibited the thermal oxidation and photodegradation of PVC.

[0082] Melt flowability: The viscosity of the experimental group was moderate, between that of the single-component methyltin and calcium-zinc composite stabilizer, which facilitated processing and molding.

[0083] 5. Overall Evaluation: The results of this comparative experiment show that: The environmentally friendly organotin stabilizer for low-odor PVC of this invention is significantly superior to traditional organotin single-component and calcium-zinc composite stabilizers in terms of odor suppression, thermal stability, and resistance to yellowing. The stabilizer has a moderate melt viscosity, which meets the requirements of PVC processing technology. The continuous distribution of the composite stable phase formed by the composite organotin host, the synergistic auxiliary stabilizer system, the molecular sieve controlled-release odor inhibitor, the interfacial orientation dispersant and the multi-level antioxidant system achieves a comprehensive performance improvement. Specific Implementation Example Six: like Figures 1 to 2 As shown, this embodiment addresses the preparation and processing of environmentally friendly organotin stabilizers for low-odor PVC under special conditions such as high temperature and humidity, rapid processing, or low temperature processing. It proposes methods for adjusting the process and formulation to ensure that the stabilizer's performance is stable, its odor is low, and its thermal stability and resistance to yellowing are not affected.

[0085] Under high-temperature processing conditions (PVC melt temperature 180–200℃), the melt compounding temperature needs to be increased to 70–75℃, and the mixing time extended by 2–3 minutes to ensure full integration of the organotin matrix and synergistic auxiliary stabilizers. Simultaneously, the pressure control accuracy for vacuum devolatilization should be improved to -0.080 MPa to reduce the impact of high-temperature volatile components on the dispersion structure of the system. In terms of formulation, the content of hindered phenolic antioxidants in the multi-stage antioxidant system can be increased by 1–2%, and the UV absorption regulating component increased by 0.5–1%. At the same time, 1–2% of molecular sieve controlled-release odor inhibitors should be appropriately added to enhance the odor suppression effect at high temperatures.

[0086] Under high-humidity raw material conditions (PVC moisture content ≥ 0.3%), the raw materials should be pre-dried (120℃, 2–4 hours), and the flow rate of inert gas should be increased during melt compounding to prevent local decomposition caused by moisture. An appropriate amount of interfacial orientation dispersant (0.5–1%) can be added to the formulation to improve the wettability and dispersion uniformity of the system, while 1–2% molecular sieves or montmorillonite can be added to adsorb residual moisture.

[0087] Under rapid processing or high shear conditions (shear rate > 600 rpm), the stirring speed needs to be increased to 500–600 rpm. Simultaneously, a segmented introduction of the interfacial orientation dispersant should be used to ensure uniform dispersion of the components under shear stress. The number of high-pressure homogenization cycles should be increased to 5–6 times to stabilize the composite structure. In terms of formulation, the proportion of long-chain alkyl tin in the composite organotin can be increased by 1–2% to improve melt viscosity control, while a suitable amount of 0.5–1% of a synergistic auxiliary stabilizer system can be added to enhance overall stability.

[0088] Under low-temperature processing conditions (melting temperature <60℃), the melting and compounding temperature should be controlled at 60–65℃, and the mixing time should be increased by 5–8 minutes to ensure full integration of all components. The vacuum devolatilization temperature should be lowered to 78–82℃ to prevent particle agglomeration. In terms of formulation, the proportion of interfacial orientation dispersant can be increased by 1–2% to improve fluidity at low temperatures. At the same time, the amount of polyhydroxy alcohol compounds in the synergistic auxiliary stabilizer system can be appropriately increased by 0.5–1% to improve low-temperature wettability and dispersibility.

[0089] Through the above process and formulation adjustment methods, the environmentally friendly organotin stabilizer for low-odor PVC prepared under special working conditions still maintains low odor, high thermal stability, excellent yellowing resistance, and good melt flowability. Its performance is consistent with that of stabilizers under conventional working conditions, providing reliable and operable guidance for industrial production.

[0090] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a reference structure" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0091] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An eco-friendly organotin stabilizer for low odor PVC comprising a stabilizer, characterized in that: The stabilizer comprises an environmentally friendly organic tin main body, a synergistic auxiliary stabilizer system, a molecular sieve controlled release odor inhibitor, an interfacial orientation dispersant, and a multi-stage antioxidant system, wherein the addition proportion of the environmentally friendly organic tin main body is 38% to 52%, the addition proportion of the synergistic auxiliary stabilizer system is 22% to 34%, the mass percentage of the molecular sieve controlled release odor inhibitor in the total stabilizer is 10% to 16%, the mass percentage of the interfacial orientation dispersant in the total stabilizer is 6% to 11%, the mass percentage of the multi-stage antioxidant system in the total stabilizer is 3% to 7%, and each component forms a continuous distribution of composite stable phases in the stabilizer.

2. A low odor environmentally friendly organotin stabilizer for PVC according to claim 1, characterized by: The environmentally friendly organic tin main body is a composite organic tin system formed by gradient distribution of at least two of methyl mercaptan tin, butyl mercaptan tin, and octyl mercaptan tin, the mass percentage of the environmentally friendly organic tin main body in the total stabilizer is 44% to 49%, the mass content of tin in the environmentally friendly organic tin main body is 19% to 21%, and the organic tin with different alkyl chain lengths in the composite organic tin system has a heterogeneous micro-distribution structure in the molten state.

3. A low odor environmentally friendly organotin stabilizer for PVC according to claim 1, characterized in that: The synergistic auxiliary stabilizer system comprises a calcium-zinc composite stabilizer, a fatty acid metal salt, and a polyhydroxy alcohol compound, wherein the calcium-zinc composite stabilizer, the fatty acid metal salt, and the polyhydroxy alcohol compound form a stable ternary structure in a mass ratio, the mass percentage of the synergistic auxiliary stabilizer system in the total stabilizer is 27% to 31%, and the overall melting transition temperature interval of the synergistic auxiliary stabilizer system is 58°C to 72°C.

4. The low odor environmentally friendly organotin stabilizer for PVC according to claim 1, characterized in that: The molecular sieve controlled release odor inhibitor is at least one of a surface-organically modified zeolite powder, an interlayer spacing regulated montmorillonite, or an embedded β-cyclodextrin, the mass percentage of the odor inhibitor in the total stabilizer is 12% to 15%, and the specific surface area of the odor inhibitor is 90㎡ / g to 140㎡ / g. The interfacial orientation dispersant is a composite dispersion system formed by a polyethylene glycol compound and a fatty acid ester compound, and the mass percentage of the interfacial orientation dispersant in the total stabilizer is 7% to 10%.

5. The low odor environmentally friendly organotin stabilizer for PVC according to claim 1, characterized in that: The multi-stage antioxidant system comprises a main antioxidant unit formed by a hindered phenolic antioxidant and a phosphite antioxidant, the stabilizer further comprises an ultraviolet absorption regulating component, the ultraviolet absorption regulating component is a benzotriazole ultraviolet absorber or a benzophenone ultraviolet absorber, the mass percentage of the ultraviolet absorption regulating component in the total stabilizer is 3% to 6%, and the antioxidant system and the ultraviolet absorption regulating component form an interlaced distribution structure in the molten state.

6. A low odor environmentally friendly organotin stabilizer for PVC according to claim 1, characterized by: The mass ratio of the environmentally friendly organic tin main body to the synergistic auxiliary stabilizer system is 1.3:1 to 1.7:1, the mass ratio of the molecular sieve controlled release odor inhibitor to the interfacial orientation dispersant is 1.6:1 to 2.1:1, the overall melting point of the stabilizer is controlled to be 48°C to 63°C, and the apparent viscosity of the stabilizer in the molten state is 9 mPa·s to 18 mPa·s.

7. The preparation process of the low-odor environmentally friendly organotin stabilizer for PVC according to any one of claims 1-6, characterized in that: The preparation process comprises the following steps: The preparation process comprises the following steps: SP1: prepare the environmentally friendly organotin main body, the synergistic auxiliary stabilizer system, the molecular sieve controlled release type odor inhibitor, the interface orientation dispersant and the multi-stage antioxidant system, the purity of each raw material is not less than 99.0%; SP2: in a closed reaction kettle, melt the environmentally friendly organotin main body and the synergistic auxiliary stabilizer system, the temperature is controlled at 62-72℃; SP3: in the melt system obtained in SP2, introduce the molecular sieve controlled release type odor inhibitor and the multi-stage antioxidant system by sub-section; SP4: add the interface orientation dispersant and continue to shear mix; SP5: the obtained mixture is subjected to vacuum devolatilization treatment; SP6: after devolatilization, cooling, homogenization and granulation.

8. The preparation process of the low-odor environmentally friendly organotin stabilizer for PVC according to claim 7, characterized in that: The SP2 is carried out under inert gas protection, the inert gas is nitrogen or helium, the stirring speed is 320-380 rpm, the mixing time is 22-28 min, and a metal complex type passivator is introduced during mixing to limit the migration of metal ions.

9. The preparation process of the low-odor environmentally friendly organotin stabilizer for PVC according to claim 7, characterized in that: In the SP3, the molecular sieve controlled release type odor inhibitor is subjected to dehydration activation treatment before being added, the activation condition is 100-110℃ for 2-3 hours, the odor inhibitor is added in batches, the amount of each batch is not more than 18% of the total amount, electromagnetic wave assisted dispersion is used between batches, the frequency is 2450-2480 MHz, and the treatment time is 8-12 min.

10. The process for the preparation of an environmentally friendly organotin stabilizer for low odor PVC according to claim 7, characterized by the fact that it comprises the following steps: In the SP4, the interface orientation dispersant is introduced in a micro-atomization manner, the atomization particle size is 1.2-2.8 μm, and the stirring speed is increased to 480-540 rpm; in the SP5, the vacuum devolatilization pressure is-0.075 to-0.065 MPa, the temperature is 82-88℃, after devolatilization, high pressure homogenization treatment is carried out, the homogenization pressure is 75-95 MPa, the cycle number is 3-5, and after homogenization, constant temperature curing treatment is carried out, the temperature is 62-68℃, and the time is 2-3 hours.

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