Environment-friendly calcium-zinc stabilizer for PVC calendering film and preparation method of environment-friendly calcium-zinc stabilizer

Abstract

The invention relates to the technical field of chemical stabilizers, and particularly discloses an environment-friendly calcium-zinc stabilizer for a PVC calendering film and a preparation method of the environment-friendly calcium-zinc stabilizer. The environment-friendly calcium-zinc stabilizer for the PVC calendering film comprises the following raw materials in parts by weight: 5-15 parts of a calcium salt stabilizer, 2-8 parts of a zinc salt stabilizer, 3-10 parts of an auxiliary stabilizer, 1-5 parts of an environment-friendly lubricant, 0.1-1 part of an antioxidant and 0.5-3 parts of a transparent modifier, the preparation method comprises the following steps: S1, pretreating the raw materials; s2, performing premixing; s3, performing secondary mixing; and S4, extruding and granulating. The environment-friendly calcium-zinc stabilizer for the PVC calendering film has the effects of environment friendliness, compliance, thermal stability, reliability, convenience in processing and capability of meeting the transparent requirement of the PVC calendering film; in addition, the preparation method disclosed by the invention has the advantages that the finished product components are uniformly dispersed, the performance stability is high, no surface precipitation defect exists, industrial continuous production is easy, and the quality consistency is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical stabilizers, in particular to an environmentally-friendly calcium-zinc stabilizer for PVC calendering film and a preparation method thereof. BACKGROUND

[0002] As a kind of polymer film material with strong plasticity and high cost-effectiveness, PVC calendering film is widely used in packaging, building materials, electronics, food contact and other fields. In the packaging field, it can be used for the protection and display packaging of various commodities. In the building materials field, it can be used as a transparent ceiling, decorative film and other components. In the food contact field, it needs to meet strict safety and hygiene standards. The processing of PVC calendering film needs to go through high-temperature melting, calendering and other links. The chlorine atoms in the PVC molecular chain are prone to degradation reactions in high-temperature environments, which can cause yellowing, embrittlement and mechanical property degradation of the film material. Therefore, stabilizers must be added to inhibit degradation and ensure the processing quality and performance of the film material. Stabilizers have become an indispensable key additive in the production of PVC calendering film.

[0003] In traditional stabilizers for PVC calendering film, lead salt stabilizers were widely used because of their good thermal stability. However, these stabilizers contain heavy metal lead, which can cause environmental pollution through soil and water sources during production, use and disposal. Although existing calcium-zinc stabilizers avoid heavy metal pollution, they still have obvious defects. Some calcium-zinc stabilizers have short thermal stability duration and can quickly fail in the high-temperature stage of PVC calendering processing, leading to early yellowing and embrittlement of the film material during processing. Some calcium-zinc stabilizers have poor compatibility with PVC resin, which can cause a decrease in the light transmittance of the film material after addition, making them unsuitable for high-transparency PVC calendering film applications. In addition, some calcium-zinc stabilizers can also affect the mechanical properties of the film material, making it prone to damage during use and difficult to meet the demand for comprehensive performance of the film material in actual applications. SUMMARY

[0004] To overcome the shortcomings of the prior art, the present application provides an environmentally-friendly calcium-zinc stabilizer for PVC calendering film and a preparation method thereof, which solves the problem of damage to the film material during use and difficulty in meeting the demand for comprehensive performance of the film material in actual applications.

[0005] To achieve the above purpose, the present application realizes the following technical scheme: an environmentally-friendly calcium-zinc stabilizer for PVC calendering film, comprising the following raw materials by weight: Calcium salt stabilizer 5-15 parts, zinc salt stabilizer 2-8 parts, auxiliary stabilizer 3-10 parts, environmentally-friendly lubricant 1-5 parts, antioxidant 0.1-1 part and transparent modifier 0.5-3 parts.

[0006] By adopting the technical scheme, since the calcium salt and the zinc salt form a basic stable system, the thermal degradation in the calendering process of PVC can be inhibited, the auxiliary stabilizer can prolong the thermal stabilization aging, avoid the rapid failure of the stabilizer, the environmentally friendly lubricant can optimize the flowability of the PVC melt, reduce the processing defects, the antioxidant can capture oxidative free radicals, delay the aging of the film material, and the transparent modifier can improve the component dispersibility and reduce light scattering. Therefore, the stabilizer for the PVC calendering film with the effects of environmental protection, non-toxicity, reliable thermal stability, good processability and adaptation to transparent requirements is obtained, and the problems of poor environmental protection and single function of the traditional stabilizer are solved.

[0007] Preferably, the calcium salt stabilizer is selected from any one or a mixture of two of calcium stearate or calcium citrate; and the zinc salt stabilizer is selected from any one or a mixture of two of zinc stearate or zinc citrate.

[0008] Preferably, the calcium salt stabilizer is a compound calcium salt formed by mixing calcium stearate and calcium citrate at a weight ratio of 2:1.

[0009] Preferably, the calcium salt stabilizer is a compound calcium salt formed by mixing calcium stearate and calcium citrate at a weight ratio of 2:1.

[0010] Preferably, the auxiliary stabilizer is selected from any one or a mixture of multiple of pentaerythritol, di-pentaerythritol or sorbitol.

[0011] Preferably, the environmentally friendly lubricant is selected from any one or a mixture of multiple of glyceryl stearate, polyethylene glycol or ethylene bis-stearamide.

[0012] Preferably, the antioxidant is selected from any one or a mixture of two of a macromolecular hindered phenolic antioxidant or a small molecule hindered phenolic antioxidant.

[0013] Preferably, the transparent modifier is selected from any one or a mixture of two of nano-silica or methyl methacrylate-butadiene-styrene copolymer, and when the nano-silica is used, the particle size thereof is 50-100 nm.

[0014] Preferably, the transparent modifier is selected from any one or a mixture of two of nano-silica or methyl methacrylate-butadiene-styrene copolymer, and when the nano-silica is used, the particle size thereof is 50-100 nm.

[0015] The application discloses a preparation method of an environment-friendly calcium-zinc stabilizer for PVC calendering film. S1, raw material pretreatment: the calcium salt stabilizer and the zinc salt stabilizer are respectively placed in a vacuum drying box and dried at a temperature of 80-100 DEG C and a vacuum degree of -0.08 to -0.06 MPa for 2-4 h, so that the water content of the calcium salt stabilizer after drying is controlled to be 0.3-0.4%, and the water content of the zinc salt stabilizer after drying is controlled to be 0.2-0.3%; S2, premixing: the calcium salt stabilizer and the zinc salt stabilizer pretreated in the step S1 are added into a high-speed mixer together with an auxiliary stabilizer, and mixed at a stirring speed of 200-300 r / min and a temperature of 50-70 DEG C for 10-20 min to obtain a premix; S3, secondary mixing: the premix obtained in the step S2 is added with an environment-friendly lubricant, an antioxidant and a transparency modifier, the stirring speed is kept unchanged, the mixing temperature is increased to 70-90 DEG C, and the mixing is continued for 5-15 min to obtain a mixture; S4, extrusion granulation: the mixture obtained in the step S3 is sent into a double-screw extruder, the temperature of the first zone of the double-screw extruder is controlled to be 120-130 DEG C, the temperature of the second zone is controlled to be 130-140 DEG C, the temperature of the third zone is controlled to be 140-150 DEG C, the die temperature is controlled to be 130-160 DEG C, the screw rotating speed is controlled to be 150-200 r / min, and after extrusion, the mixture is cut by a granulator and air-cooled to 25±5 DEG C to obtain the environment-friendly calcium-zinc stabilizer for PVC calendering film. By adopting the technical scheme, the water content of the raw materials is controlled through the pretreatment in the step S1, so that the hydrolysis of the stabilizer and the bubbles of the film material caused by water are avoided, the preliminary dispersion of the calcium-zinc salt and the auxiliary stabilizer is realized through the premixing in the step S2, the local concentration deviation is reduced, the melting of the lubricant is promoted through the temperature increase in the step S3, so that the antioxidant and the transparency modifier are uniformly wrapped, the material degradation is avoided through the segmented temperature control extrusion in the step S4, and the product quality is controlled through the air cooling, so that the environment-friendly calcium-zinc stabilizer for PVC calendering film with stable performance, no caking and adhesion and industrialized mass production effect is obtained, and the problems of uneven dispersion of raw materials and fluctuation of product quality in the preparation process are solved.

[0016] Preferably, in the step S2, the stirring speed of the high-speed mixer is 250-280 r / min, the mixing temperature is 60-65 DEG C, and the mixing time is 15-18 min.

[0017] Preferably, in the step S3, after the environment-friendly lubricant, the antioxidant and the transparency modifier are added, the mixing temperature is controlled to be 75-85 DEG C, and the mixing time is controlled to be 8-12 min. In the step S4, the screw rotating speed of the double-screw extruder is 170-190 r / min, the die temperature is controlled to be 140-155 DEG C, and the cold air speed is 2-3 m / s in the air cooling process, so that the product temperature is stably controlled to be 25±5 DEG C.

[0018] By adopting the technical scheme, since the temperature and time of S3 can ensure complete melting of the lubricant, the antioxidants, the transparent modifier and the premix are fully fused, the rotating speed and the die temperature of S4 can ensure complete melting of the material without degradation, the compactness of the finished product particles is improved, the air cooling wind speed of 2-3 m / s can quickly cool the finished product, and particle adhesion is avoided, therefore, the effect of more uniform component distribution, better particle quality, and strong performance consistency of the finished product is obtained, and the performance fluctuation problem of the finished product caused by improper secondary mixing and extrusion parameters is solved.

[0019] The application provides an environmentally-friendly calcium-zinc stabilizer for PVC calendering film and a preparation method thereof. 1. The calcium salt stabilizer, zinc salt stabilizer, auxiliary stabilizer, environmentally-friendly lubricant, antioxidant and transparent modifier are combined in the application, each component can play the roles of inhibiting PVC thermal degradation, prolonging anti-aging time, improving processing fluidity, hindering oxidation reaction and optimizing film material transparency, and each component can form a complementary function to avoid the defects of poor environmental protection, single function and the like of a single stabilizer or a simple mixed system, and the comprehensive effect of considering environmental protection compliance, reliable thermal stability, convenient processing and adapting to the transparent demand of PVC calendering film is obtained, and the basic use requirements of PVC calendering film in different scenes can be met.

[0020] 2. The calcium salt stabilizer prepared by compounding calcium stearate and calcium citrate at a specific ratio, the mixed use of macromolecules and small molecule hindered phenolic antioxidants, and the combination of specific types of transparent modifiers in the application, since the compounded calcium salt can strengthen the synergistic effect of calcium-zinc ions and reduce the influence of ion migration on the performance of PVC, the mixed antioxidants can cover the antioxidant demand in the whole PVC processing cycle, the problem of insufficient protection of a single antioxidant in the initial or later stage is avoided, and the specific transparent modifier can reduce particle agglomeration and reduce the interference of light scattering on the transparency of the film material, so that better thermal stability, comprehensive antioxidant performance and film material transparency are obtained, and the higher performance requirements of medium and high-end PVC calendering film are met.

[0021] 3. The method of the application can remove free water in the raw materials through pretreatment, avoid hydrolysis of the stabilizer and processing defects of the film material caused by water, ensure the dispersion of each component from the initial stage to the deep fusion stage through the staged mixing, prevent performance fluctuations caused by local concentration unevenness, and ensure complete melting of the material without excessive degradation through the segmented temperature control extrusion, so that the effect of uniform dispersion of the finished product components, strong performance stability, no surface precipitation defects and easy industrial continuous production is obtained, and the quality consistency of the product batch production is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1The method flow chart of the preparation method of the environment-friendly calcium-zinc stabilizer for PVC calendering film. DETAILED DESCRIPTION

[0023] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0024] Please refer to the drawings of the present application Figure 1 The environment-friendly calcium-zinc stabilizer for PVC calendering film provided by the embodiments of the present application comprises the following raw materials by weight: The calcium salt stabilizer is any one or a mixture of two of calcium stearate or calcium citrate; the zinc salt stabilizer is any one or a mixture of two of zinc stearate or zinc citrate.

[0025] The calcium salt stabilizer is any one or a mixture of two of calcium stearate or calcium citrate; the zinc salt stabilizer is any one or a mixture of two of zinc stearate or zinc citrate.

[0026] The calcium salt stabilizer is a compound calcium salt formed by mixing calcium stearate and calcium citrate in a weight ratio of 2:1.

[0027] The auxiliary stabilizer is any one or a mixture of multiple of pentaerythritol, di-pentaerythritol or sorbitol.

[0028] The environment-friendly lubricant is any one or a mixture of multiple of glyceryl stearate, polyethylene glycol or ethylene bis-stearamide.

[0029] The antioxidant is any one or a mixture of two of macromolecular hindered phenolic antioxidant or small-molecule hindered phenolic antioxidant.

[0030] The transparent modifier is any one or a mixture of two of nano-silicon dioxide or methyl methacrylate-butadiene-styrene copolymer, and when nano-silicon dioxide is used, the particle size is 50-100 nm.

[0031] The preparation method of the environment-friendly calcium-zinc stabilizer for PVC calendering film comprises the following steps: S1, raw material pretreatment: the calcium salt stabilizer and the zinc salt stabilizer are respectively placed in a vacuum drying box and dried at a temperature of 80-100 DEG C and a vacuum degree of-0.08~ -0.06 MPa for 2-4 h, so that the water content of the calcium salt stabilizer after drying is controlled to be 0.3-0.4%, and the water content of the zinc salt stabilizer after drying is controlled to be 0.2-0.3%; S2, premixing: the calcium salt stabilizer, zinc salt stabilizer and auxiliary stabilizer after pretreatment in step S1 are added into a high-speed mixer, mixed at 200-300 r / min, 50-70℃ for 10-20 min to obtain a premix; S3, secondary mixing: the premix obtained in step S2 is added with environmental lubricant, antioxidant and transparency modifier, the stirring speed is kept unchanged, the mixing temperature is increased to 70-90℃, and the mixing is continued for 5-15 min to obtain a mixture; S4, extrusion and granulation: the mixture obtained in step S3 is sent into a double screw extruder, the temperature of the first zone is controlled at 120-130℃, the temperature of the second zone is controlled at 130-140℃, the temperature of the third zone is controlled at 140-150℃, the temperature of the die head is controlled at 130-160℃, the screw speed is controlled at 150-200 r / min, and the mixture is cut into particles by a granulator after extrusion, and then air-cooled to 25±5℃ to obtain the finished product of the environmental calcium-zinc stabilizer for PVC calendering film In step S2, the stirring speed of the high-speed mixer is 250-280 r / min, the mixing temperature is 60-65℃, and the mixing time is 15-18 min.

[0032] In step S3, after adding the environmental lubricant, antioxidant and transparency modifier, the mixing temperature is controlled at 75-85℃, and the mixing time is controlled at 8-12 min. In step S4, the screw speed of the double screw extruder is 170-190 r / min, the temperature of the die head is controlled at 140-155℃, and the air speed during air cooling is 2-3 m / s to ensure that the temperature of the finished product is stable at 25±5℃.

[0033] The following will be described in combination with specific examples: Example 1 An environmental calcium-zinc stabilizer for PVC calendering film comprises the following raw materials by weight: The calcium salt stabilizer is 5 parts, which is compounded by calcium stearate and calcium citrate at a ratio of 2:1, the zinc salt stabilizer is 2 parts of zinc stearate, the auxiliary stabilizer is 3 parts of pentaerythritol, the environmental lubricant is 1 part of glycerol stearate, the antioxidant is 0.1 part of macromolecular hindered phenolic antioxidant 1010, and the transparency modifier is 0.5 part of nano-silicon dioxide with a particle size of 50-100 nm.

[0034] A preparation method of an environmental calcium-zinc stabilizer for PVC calendering film, comprising the following steps: S1 raw material pretreatment: the compounded calcium salt stabilizer and zinc stearate are respectively loaded into a dry tray and placed in a vacuum drying oven, the temperature is set to 90℃, the vacuum degree is-0.07MPa, and the drying is continued for 3h. After drying, the water content of the calcium salt is 0.35% and the water content of the zinc salt is 0.25%, both of which meet the control requirement of ≤0.5%, avoiding clumping in subsequent mixing; S2 premixing: the pretreated calcium salt, zinc salt and pentaerythritol are added into a high-speed mixer, the stirring speed is set to 250r / min, and the mixing temperature is 60℃. The mixture is continuously mixed for 15min, and the sample is observed every 5min to ensure that the material has no obvious clumping, and finally a loose and uniform premix is formed; S3 secondary mixing: the premix is added with glycerol stearate, antioxidant 1010 and nano silicon dioxide, the stirring speed is kept at 250r / min, the mixing temperature is raised to 75℃, and the mixing is continued for 8min. After mixing, the material is in the form of uniform particles without agglomeration, ensuring that the functional components are fully dispersed.

[0035] S4 extrusion granulation: the secondary mixed material is sent into a double screw extruder for extrusion, the temperature of each zone is set to 120℃, 130℃ and 140℃ respectively, the die temperature is 140℃, and the screw speed is 170r / min. The extruded material is cooled in a water tank with water temperature of 20℃, then cut into 3-5mm long particles by a granulator, and cooled to 25℃ by a air cooling machine with air speed of 2m / s to obtain finished particles. The particle surface is smooth and non-sticky.

[0036] Example 2: An environmentally friendly calcium-zinc stabilizer for PVC calendering film, comprising the following raw materials by weight: Calcium salt stabilizer 10 parts, selected from calcium stearate and calcium citrate at a ratio of 2:1, zinc salt stabilizer 5 parts, selected from 3 parts of zinc stearate and 2 parts of zinc citrate, auxiliary stabilizer 6 parts, selected from 4 parts of pentaerythritol and 2 parts of bis-pentaerythritol, environmentally friendly lubricant 3 parts, selected from 2 parts of glycerol stearate and 1 part of polyethylene glycol 4000, antioxidant 0.5 parts, selected from 0.3 parts of antioxidant 1010 and 0.2 parts of antioxidant 1076, transparency modifier 1.5 parts, selected from 1 part of nano silicon dioxide and 0.5 part of methyl methacrylate-butadiene-styrene copolymer (MBS).

[0037] A preparation method of an environmentally friendly calcium-zinc stabilizer for PVC calendering film, comprising the following steps: S1 raw material pretreatment: the drying temperature is set to 95℃, the vacuum degree is-0.07MPa, and the drying time is 3h. After drying, the water content of the calcium salt is 0.32% and the water content of the zinc salt is 0.22%, the water control is more accurate, and the subsequent mixing uniformity is further improved. S2 premixing: the speed of the high-speed mixer is adjusted to 260 r / min, the mixing temperature is 62°C, and the mixing time is 16 min; S3 secondary mixing: the mixing temperature is increased to 80°C, and the mixing time is 10 min; S4 extrusion granulation: the temperature of each zone of the double-screw extruder is adjusted to 125°C for the first zone, 135°C for the second zone, and 145°C for the third zone, the die temperature is 145°C, the screw speed is 180 r / min, the air speed of the air cooler is increased to 2.5 m / s, and the finished product is cooled to 24°C.

[0038] Example 3 An environmentally friendly calcium-zinc stabilizer for PVC calendering film includes the following raw materials by weight: The calcium salt stabilizer is 15 parts, selected from calcium stearate and calcium citrate in a ratio of 2:1, the zinc salt stabilizer is 8 parts of zinc citrate, the auxiliary stabilizer is 10 parts, selected from the mixture of 5 parts of pentaerythritol, 3 parts of di-pentaerythritol, and 2 parts of sorbitol, the environmentally friendly lubricant is 5 parts, selected from the mixture of 2 parts of glycerol stearate, 2 parts of polyethylene glycol 4000, and 1 part of ethylene bis-stearamide, the antioxidant is 1 part, selected from the single use of small molecule hindered phenolic antioxidant 1076, the transparency modifier is 3 parts, selected from MBS.

[0039] A preparation method of an environmentally friendly calcium-zinc stabilizer for PVC calendering film, the method includes the following steps: S1 raw material pretreatment: the drying temperature is increased to 100°C, the vacuum degree is -0.08 MPa, and the drying time is extended to 4 h, after drying, the water content of the calcium salt is 0.38%, and the water content of the zinc salt is 0.28%; S2 premixing: the speed of the high-speed mixer is increased to 280 r / min, the mixing temperature is 65°C, and the mixing time is 18 min; S3 secondary mixing: the mixing temperature is increased to 85°C, and the mixing time is 12 min; S4 extrusion granulation: the temperature of each zone of the double-screw extruder is increased to 130°C for the first zone, 140°C for the second zone, and 150°C for the third zone, the die temperature is 155°C, the screw speed is 190 r / min, the air speed of the air cooler is increased to 3 m / s, the high-content particles are quickly cooled to prevent agglomeration, and the finished product is cooled to 26°C.

[0040] Example 4 The zinc salt stabilizer is 5 parts of zinc citrate, and the remaining raw materials, proportions, and method steps are consistent with those of Example 2.

[0041] Example 5 The auxiliary stabilizer is 6 parts of sorbitol, and the remaining raw materials, proportions, and method steps are consistent with those of Example 2.

[0042] Example 6 The antioxidant is 0.5 part of antioxidant 1076, and the remaining raw materials, parts, and method steps are consistent with example 2.

[0043] Comparative example 1 The S1 raw material pretreatment step is omitted, and commercially available raw materials are directly used. The initial water content of the calcium salt stabilizer is about 1.8%, and the initial water content of the zinc salt is about 1.6%. The remaining raw materials, parts, and method steps are consistent with example 2.

[0044] Comparative example 2 The transparent modifier is deleted, and the remaining raw material parts remain unchanged. The remaining raw materials, parts, and method steps are consistent with example 2.

[0045] Comparative example 3 The environmentally friendly lubricant is replaced with paraffin wax. The remaining raw materials, parts, and method steps are consistent with example 2.

[0046] Comparative example 4 The nano-silicon dioxide in the transparent modifier is replaced with ordinary silicon dioxide with a particle size of 200 nm and material parameters changed. The remaining raw materials, parts, and method steps are consistent with example 2.

[0047] Table 1, detection data table of calcium-zinc stabilizer for PVC calendering film

[0048] As can be seen from examples 1-3, comparative examples 1-4, and table 1, the examples and comparative examples have obvious differences in the three key properties of heat stabilization time, light transmittance, and tensile strength. The heat stabilization time of the examples is longer than that of the comparative examples, and the light transmittance and tensile strength are higher than those of the comparative examples. Among them, the heat stabilization time of example 2 is the longest, and the light transmittance and tensile strength are the highest, indicating that its comprehensive performance is the best. In terms of light transmittance and tensile strength, the examples are generally better than the comparative examples, and the light transmittance of example 2 reaches 89% and the tensile strength reaches 27 MPa, showing more excellent transparency and mechanical properties. This shows that the raw material ratio and preparation method used in the present application can effectively improve the comprehensive performance of the environmentally friendly calcium-zinc stabilizer for PVC calendering film, and the formula and process of example 2 perform best in the balance of heat stability, transparency, and mechanical properties.

[0049] The heat stabilization time in the table is a key indicator of the material's resistance to thermal degradation (min), and the longer the value, the better the resistance to thermal degradation. The light transmittance is a material transparency indicator (%), and the higher the value, the better the transparency. The tensile strength is a material mechanical property indicator (MPa), and the larger the value, the stronger the mechanical properties.

[0050] The thermal stability time of Example 2 in Examples 1 to 6 is up to 75 min, the light transmittance is up to 89%, the tensile strength is up to 27 MPa, the calcium salt stabilizer is a 2:1 compound of calcium stearate and calcium citrate, the zinc salt stabilizer is a mixture of zinc stearate and zinc citrate, the auxiliary stabilizer is a mixture of pentaerythritol and dipentaerythritol, the antioxidant is a mixture of 1010 and 1076, and the transparency modifier is a mixture of nano-silicon dioxide and MBS, and the synergistic effect is remarkable.

[0051] The compound calcium zinc salt forms a synergistic stabilizing system in the system, the calcium salt supplements the active sites consumed by the zinc salt to avoid zinc burning, the auxiliary stabilizer and the antioxidant together capture free radicals to inhibit oxidative degradation, the transparent modifier uniformly disperses to reduce light scattering to ensure transparency, the raw material pretreatment controls humidity, the premixing and secondary mixing optimize temperature and speed, and the extrusion granulation parameter control strengthens the overall performance.

[0052] Comparative Examples 1 to 2, the thermal stability time is 38-73 min, the light transmittance is 68-75%, and the tensile strength is 19-24 MPa. Because the raw material pretreatment step is omitted or the transparent modifier is deleted, the performance system is incomplete, and it cannot effectively resist the influence of thermal degradation and light scattering, resulting in unsatisfactory thermal stability performance, transparency performance and mechanical performance.

[0053] Comparative Example 3, the thermal stability time is 74 min, the light transmittance is 80%, and the tensile strength is 22 MPa. Compared with Example 2, it is significantly worse. Because the environmentally friendly lubricant is replaced by paraffin wax, paraffin wax has poor compatibility with PVC and does not meet environmental protection requirements. It not only easily migrates from the surface of the film material to cause blooming, but also produces light scattering to reduce light transmittance. At the same time, the lack of compatibility makes the mechanical properties of the film material decrease. Although the influence on thermal stability is small, the overall performance is greatly damaged.

[0054] Comparative Example 4, the thermal stability time is 75 min, the light transmittance is 76%, and the tensile strength is 25 MPa. Although the thermal stability performance is the same as that of Example 2, the transparency performance is still lacking. Because the nano-silicon dioxide in the transparent modifier is replaced by ordinary silicon dioxide with a particle size of 200 nm, the ordinary silicon dioxide has a large particle size and easily agglomerates, which produces obvious light scattering in the PVC matrix, resulting in a decrease in light transmittance. Although it does not affect the thermal stability and mechanical properties, it cannot meet the demand of high-transparency PVC calendering film.

[0055] The thermal stability time (unit: min) is detected by Congo red method, referring to the national standard “GB / T2917.1-2002 Determination of thermal stability time at high temperature for blends and products based mainly on homopolymers and copolymers of vinyl chloride Part 1: Congo red method”, which is suitable for the evaluation of thermal stability performance of PVC materials processed at high temperature with a temperature of 180℃.

[0056] For example 1 to example 6 and comparative example 1 to comparative example 4, the PVC mixture material was prepared according to the corresponding formula: based on 100 parts of PVC resin, the stabilizer was added, and then 30 parts of industrial grade plasticizer DOP was added, the above material was added into a high-speed mixer, the speed was 300 r / min, the temperature was 80℃, and the mixing time was 10 min, to obtain the corresponding PVC mixture material of each case, the PVC mixture material was placed into a flat vulcanizing machine, and a circular test piece with a thickness of 1.0±0.1 mm and a diameter of 30 mm was prepared under the conditions of a temperature of 180℃ and a pressure of 15 MPa for 5 min, and then the circular test piece was cooled to room temperature for standby, and three groups of parallel test pieces were prepared for each example and comparative example; A Congo red hot stability instrument, an analytical balance, a flat vulcanizing machine, Congo red test paper and anhydrous ethanol were used, 2.0±0.1 g of the prepared PVC test piece was crushed and then was loaded into a glass test tube, and was compacted to 1 / 3 of the bottom of the test tube, 10 mm×50 mm of Congo red test paper was cut, one end of the Congo red test paper was fixed under a rubber plug with a fine wire, and the other end of the Congo red test paper was hung above the test piece, the bottom edge of the Congo red test paper was 5 mm away from the surface of the test piece and did not contact the test piece, and the test tube was tightly plugged. The test tube was vertically placed into an oil bath of the Congo red hot stability instrument which was preheated to 180℃, it was ensured that the test piece in the test tube was completely immersed in the oil bath, the oil surface was 10 mm higher than the upper surface of the test piece, and the timing was started, the color change of the Congo red test paper was observed every 1 min, and whether the test piece was obviously yellow was observed, when the Congo red test paper first appeared blue spots or the test piece was obviously yellow, the timing was stopped, and the recorded time was the hot stability time, the parallel test of each example and comparative example was performed for three times, and the average value was taken as the final hot stability time result of the case.

[0057] The light transmittance (unit: %) was detected by using an ultraviolet visible spectrophotometer, referring to the national standard “GB / T 2410-2008 Determination of Light Transmittance and Haze of Transparent Plastics”, and the test wavelength was 550 nm, and the film thickness was controlled to be 0.1 mm.

[0058] The PVC mixture material corresponding to each of example 1 to example 6 and comparative example 1 to comparative example 4 was taken and was placed into a calendering machine, the temperature was 160℃, the roller speed was 20 r / min, and a PVC calendering film with a thickness of 0.1±0.01 mm, a width of 100 mm and a length of 200 mm was prepared by calendering. The surface of the PVC calendering film of each case was cleaned with anhydrous ethanol to remove oil stains and impurities, and five square samples with a size of 50 mm×50 mm were cut from each case, and it was ensured that the samples were free of wrinkles, bubbles and scratches.

[0059] An ultraviolet visible spectrophotometer, a film sample holder, a precision caliper and a dust-free cloth were used to measure the film thickness and clean the sample and the light path of the instrument. Turn on the preheating of the UV-visible spectrophotometer for 30 min, calibrate the light path, take air as the blank control, calibrate the transmittance as 100%, fix the sample of each case on the film sample holder, ensure that the sample is flat, has no tilt, and completely covers the light path, set the test wavelength as 550 nm, and the instrument displays the transmittance value of the sample; Test 5 points in different positions of each sample, i.e., the upper left, the upper right, the center, the lower left, and the lower right, and take the average value as the final transmittance of the case. If the sample of a case has bubbles or scratches, the sample of the case needs to be prepared again for testing.

[0060] The tensile strength (unit: MPa) is detected according to the national standard “GB / T1040.3-2006 Determination of tensile properties of plastics Part 3: test conditions for films and sheets”, and the “type I sample” (dumbbell type) is adopted to adapt to the mechanical property evaluation of the PVC calendering film.

[0061] Take the PVC calendering film, which is consistent with the calendering film of each case in the transmittance detection, with a thickness of 0.1±0.01 mm, use a dumbbell-shaped cutting tool, which meets the GB / T1040.3-2006 type I specification, and cut it into 5 samples respectively; Use a precision caliper to measure the thickness of each sample in each case, measure 3 points, take the average value, and measure the width, measure 2 points, take the average value, and record the data for calculating the cross-sectional area of each sample.

[0062] A universal material testing machine is equipped with a film special fixture, a dumbbell-shaped cutting tool, and a digital vernier caliper.

[0063] Turn on the preheating of the universal material testing machine for 30 min, calibrate the force value and displacement, set the test parameters as a tensile speed of 50 mm / min, a pre-tension of 0.5 N, and a test termination condition of sample fracture; Clamp the two ends of the sample of each case in the upper and lower clamps of the testing machine, respectively, ensure that the sample axis is aligned with the center line of the clamp, the gage length section is wrinkle-free, and the testing machine records the tension and displacement curve. When the sample is broken, stop the test and read the maximum tension value; Calculate the tensile strength according to the formula: Tensile strength (MPa) = maximum tension value (N) / sample cross-sectional area (mm 2 ); The cross-sectional area = average thickness of gage length × average width. After the test of 5 samples of each case is completed, remove the abnormal value, and take the average value of the remaining samples as the final tensile strength result.

[0064] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. An environmentally friendly calcium-zinc stabilizer for PVC calendering film, characterized in that, The raw materials include the following weight parts: calcium salt stabilizer 5-15 parts, zinc salt stabilizer 2-8 parts, auxiliary stabilizer 3-10 parts, environmentally friendly lubricant 1-5 parts, antioxidant 0.1-1 part and transparency modifier 0.5-3 parts.

2. The environment-friendly calcium-zinc stabilizer for PVC calendering film according to claim 1, characterized in that: The calcium salt stabilizer is selected from any one or mixture of two of calcium stearate or calcium citrate; the zinc salt stabilizer is selected from any one or mixture of two of zinc stearate or zinc citrate.

3. The environment-friendly calcium-zinc stabilizer for PVC calendering film according to claim 1, characterized in that: The calcium salt stabilizer is a compound calcium salt formed by mixing calcium stearate and calcium citrate in a weight ratio of 2:

1.

4. The environment-friendly calcium-zinc stabilizer for PVC calendering film according to claim 1, characterized in that: The auxiliary stabilizer is selected from any one or mixture of more than one of pentaerythritol, di-pentaerythritol or sorbitol.

5. The environmentally friendly Ca / Zn stabilizer for PVC calendering film according to claim 1, characterized in that: The environmentally friendly lubricant is selected from any one or mixture of more than one of glyceryl stearate, polyethylene glycol or ethylene bis-stearamide.

6. The environmentally friendly Ca / Zn stabilizer for PVC calendering film according to claim 1, characterized in that: The antioxidant is selected from any one or mixture of two of macromolecular hindered phenolic antioxidant or small molecule hindered phenolic antioxidant.

7. The environmentally friendly Ca / Zn stabilizer for PVC calendering film according to claim 1, characterized in that: The transparency modifier is selected from any one or mixture of two of nano-silicon dioxide or methyl methacrylate-butadiene-styrene copolymer, and when nano-silicon dioxide is selected, the particle size is 50-100 nm.

8. A method for preparing an environmentally friendly calcium-zinc stabilizer for PVC calendering film, characterized in that, An environmentally friendly calcium-zinc stabilizer for a PVC calender film according to any one of claims 1-7, the method comprising the following steps: S1, raw material pretreatment: the calcium salt stabilizer and the zinc salt stabilizer are respectively placed in a vacuum drying oven, dried at a temperature of 80-100°C and a vacuum degree of -0.08~-0.06MPa for 2-4h, and the water content of the calcium salt stabilizer after drying is controlled to be 0.3-0.4%, and the water content of the zinc salt stabilizer after drying is controlled to be 0.2-0.3%; S2, premixing: the calcium salt stabilizer and the zinc salt stabilizer pretreated in step S1 are added to a high-speed mixer together with the auxiliary stabilizer, mixed at a stirring speed of 200-300r / min and a temperature of 50-70°C for 10-20min to obtain a premix; S3, secondary mixing: the premix obtained in step S2 is added with the environmentally friendly lubricant, the antioxidant and the transparency modifier, the stirring speed is kept unchanged, the mixing temperature is raised to 70-90°C, and the mixing is continued for 5-15min to obtain a mixture; S4, extrusion granulation: the mixture obtained in step S3 is sent into a double-screw extruder, the temperature of the first zone of the double-screw extruder is controlled to be 120-130°C, the temperature of the second zone is controlled to be 130-140°C, the temperature of the third zone is controlled to be 140-150°C, the die temperature is controlled to be 130-160°C, the screw rotation speed is controlled to be 150-200r / min, and after extrusion, the particles are cut by a granulator and air-cooled to 25±5°C to obtain the finished product of the environmentally friendly calcium-zinc stabilizer for a PVC calender film.

9. The preparation method of the environmentally-friendly calcium-zinc stabilizer for PVC calendering film according to claim 8, characterized in that: In step S2, the stirring speed of the high-speed mixer is 250-280r / min, the mixing temperature is 60-65°C, and the mixing time is 15-18min.

10. The method for preparing an environmentally-friendly calcium-zinc stabilizer for PVC calendering film according to claim 8, characterized in that: In step S3, after the environmentally friendly lubricant, the antioxidant and the transparency modifier are added, the mixing temperature is controlled to be 75-85°C, and the mixing time is controlled to be 8-12min. In the step S4, the screw rotation speed of the double screw extruder is 170-190 r / min, the die temperature is controlled at 140-155 ℃, and the cold air speed is 2-3 m / s in the air cooling process, so as to ensure that the product temperature is stable at 25±5 ℃.

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