High-elasticity PVC film and preparation method thereof

Abstract

The invention discloses a high-elasticity PVC film and a preparation method thereof, and relates to the technical field of PVC films. The invention relates to a high-elasticity PVC (polyvinyl chloride) film, which comprises PVC resin powder, a calcium-zinc stabilizer, a bio-based branched plasticizer, POE (polyolefin elastomer) coated calcium carbonate, CPE (chlorinated polyethylene) and other processing aids, the epoxidized soybean oil-based polyol is specifically prepared from epoxidized soybean oil and methanol through a ring-opening reaction. Through the technical scheme of the invention, the PVC film which not only has excellent flexibility and high elasticity, but also has good mechanical strength and tear resistance can be prepared.

Description

A highly elastic PVC film and its preparation method Technical Field

[0001] This invention relates to the field of PVC film, and in particular to a highly elastic PVC film and its preparation method. Background Technology

[0002] PVC film, as a high-performance polymer material, is widely used in medical devices, automotive interior panels, sports protective gear, and building waterproof membranes due to its good chemical stability, flame retardancy, and controllable physical properties.

[0003] Traditional PVC films have relatively high rigidity in their original state. To meet the demands of flexible applications for high elasticity and flexibility, the industry commonly uses plasticizers to modify them for flexibility. By adding a large amount of small-molecule plasticizers such as phthalates and terephthalates to the PVC film matrix, these plasticizers can effectively insert into the PVC molecular chains and weaken the interchain forces, significantly reducing the glass transition temperature of the PVC film and thus improving its flexibility and resilience.

[0004] However, in actual production, to achieve the desired flexibility and elasticity, a relatively large amount of plasticizer is often required. As the amount of plasticizer added increases, it also causes a series of adverse effects on the PVC film. First, excessive plasticizer directly leads to a decrease in the mechanical properties of the PVC film, specifically a significant reduction in tensile strength and weakened tear resistance. This makes the PVC film prone to breakage under external force, failing to meet the strength requirements of actual use. Second, small-molecule plasticizers typically have a certain degree of migration. Adding large amounts will exacerbate the migration of plasticizers towards the film surface or the contacting medium. This not only causes the performance of the PVC film to gradually deteriorate over time, such as decreased flexibility and elasticity, hardening and brittleness, and surface stickiness, but may also contaminate contacted items due to plasticizer migration, especially in the medical device field, posing serious safety hazards. Therefore, developing a PVC film with excellent overall performance and low plasticizer migration is of great significance. Summary of the Invention

[0005] In order to further improve the overall performance of PVC film, so that PVC film not only has excellent flexibility and high elasticity, but also good mechanical strength and tear resistance, while reducing the performance degradation of PVC film or the contamination of items caused by excessive migration of plasticizers, this application provides a high elasticity PVC film and its preparation method.

[0006] In the first aspect, the high-elasticity PVC film provided in this application adopts the following technical solution: A high-elasticity PVC film, comprising the following raw materials in parts by weight: PVC resin powder: 100 parts; calcium-zinc stabilizer: 4-6 parts; bio-based branched plasticizer: 40-50 parts; POE-coated calcium carbonate: 5-10 parts; CPE: 8-10 parts; ACR impact modifier: 1-2.5 parts; lubricant: 1.2-1.8 parts; light stabilizer: 0.5-0.8 parts; pigments and fillers: 0.5-3 parts; wherein, the bio-based branched plasticizer is prepared by reaction of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid and ε-caprolactone, and the epoxidized soybean oil-based polyol is specifically prepared by ring-opening reaction of epoxidized soybean oil and methanol.

[0007] By employing the above technical solution, and using bio-based branched plasticizers and POE-coated calcium carbonate to modify PVC films, PVC films with excellent flexibility and high elasticity, as well as good mechanical strength and tear resistance, can be produced. Furthermore, the loss of mechanical properties in the PVC film is minimal even after prolonged aging, which helps maintain its good flexibility and elasticity over a long period.

[0008] Optionally, the preparation method of the bio-based branched plasticizer includes the following steps: A1. Dissolve methanol in dichloromethane, heat to 60-65℃, add epoxidized soybean oil and catalyst I in proportion, continue heating to 100-105℃, and continue stirring the reaction for 2-3 hours after reaching the target temperature. Then remove catalyst I to terminate the reaction, and remove dichloromethane and methanol by vacuum distillation to obtain epoxidized soybean oil-based polyol; A2. Add the epoxidized soybean oil-based polyol obtained in step A1, 2,2-dimethylolpropionic acid and toluene to a reaction vessel, and introduce... An inert gas is used to heat the product to 115-120℃ in an inert atmosphere and preheat for 20-30 minutes. Then, catalyst II and polymerization inhibitor are added under stirring. The product is heated to 135-140℃ and stirred for more than 12 hours in an inert atmosphere, during which water is continuously separated until no obvious water is generated in the separator, thus obtaining a branched polyol. After the branched polyol is cooled to 120-130℃, ε-caprolactone is added and stirred evenly. The temperature is maintained and the reaction is stirred for 6-8 hours. After the reaction is completed, the product is distilled under vacuum to obtain a bio-based branched plasticizer.

[0009] By adopting the above technical solution, a bio-based branched plasticizer with a macromolecular and highly branched structure can be prepared. This not only realizes the conversion of bio-based raw materials, but also, compared with traditional bio-based plasticizers, the prepared bio-based branched plasticizer has the effect of migration resistance and long-term flexibility in PVC film production due to its special highly branched structure, which is conducive to maintaining good flexibility and elasticity of PVC film for a long time.

[0010] Optionally, in step A1, the molar ratio of epoxidized soybean oil to methanol is 1:(4.2-4.5), and the amount of catalyst I added is 0.5-1% of the total mass of epoxidized soybean oil and methanol; in step A2, the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid, and ε-caprolactone is 1:(4.5-5):(10-20), the amount of toluene added is 30-40% of the mass of epoxidized soybean oil-based polyol, the amount of catalyst II added is 0.5-1.5% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid, and the amount of polymerization inhibitor added is 0.05-0.1% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid.

[0011] By adopting the above technical solution, it is beneficial to ensure that the reaction at each stage is fully carried out. Moreover, when the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid and ε-caprolactone is controlled within the range of 1:(4.5-5):(10-20), it is beneficial to prevent the adverse effect of a significant decrease in the mechanical properties of PVC film after aging due to the high content of ε-caprolactone. It is also beneficial to ensure that the PVC film still has high mechanical properties after long-term use.

[0012] Optionally, in step A1, catalyst I is specifically a sulfuric acid / zirconium dioxide solid acid catalyst; in step A2, catalyst II is either stannous octoate or dibutyltin dilaurate, and the polymerization inhibitor is specifically hydroquinone.

[0013] By employing the above technical solution and using a sulfuric acid / zirconium dioxide solid acid catalyst as the catalyst for the synthesis of epoxidized soybean oil-based polyols, not only can the ring-opening reaction between epoxidized soybean oil and methanol be catalyzed efficiently, but also, due to its solid nature, it can be removed by simple filtration, thereby terminating the reaction and achieving control over the reaction process. Furthermore, either stannous octoate or dibutyltin dilaurate is selected as catalyst II, and hydroquinone is selected as a polymerization inhibitor. The former not only catalyzes the esterification reaction of epoxidized soybean oil-based polyols with 2,2-dimethylolpropionic acid, but also significantly catalyzes the polymerization reaction of branched polyols with ε-caprolactone, which is beneficial to ensuring the construction of large molecules and highly branched structures and reaction efficiency of bio-based branched plasticizers; the latter can effectively inhibit side reactions such as the self-polymerization of 2,2-dimethylolpropionic acid during the reaction process, which is beneficial to ensuring the normal progress of the reaction.

[0014] Optionally, the preparation method of the POE-coated calcium carbonate includes the following steps: B1, by mass, calcium carbonate and titanate coupling agent are first fully mixed in a high-speed mixer so that the titanate coupling agent is uniformly coated on the surface of calcium carbonate to obtain pretreated calcium carbonate; B2, the pretreated calcium carbonate obtained in step B1 is then fully mixed with POE granules and calcium stearate and added to an extruder for melt extrusion granulation. After natural cooling and drying, the POE-coated calcium carbonate is obtained.

[0015] By adopting the above technical solution, POE can form a flexible and deformable transition layer on the surface of calcium carbonate. This not only effectively transfers and disperses the stress on the PVC film, but also allows the POE molecular chains coated on the calcium carbonate surface to fully entangle with the PVC molecular chains under the action of CPE. This enables the POE-coated calcium carbonate, as a filler, to fully combine with the PVC, which is beneficial to further improve the reinforcing and toughening effect of POE-coated calcium carbonate.

[0016] Optionally, the mass ratio of the POE granules, the calcium carbonate, the calcium stearate, and the titanate coupling agent is 100:(30-50):(0.8-1):(4-6), wherein the titanate coupling agent is specifically selected from titanate coupling agents.

[0017] By adopting the above technical solution, and by controlling the mixing mass ratio of POE granules to calcium carbonate within the range of 100:(30-50), it is beneficial to ensure the reinforcing and toughening effect of POE-coated calcium carbonate on PVC film. At the same time, it can also prevent the adverse effect of a significant decrease in the flexibility and elasticity of PVC film after aging due to excessive calcium carbonate content. This is beneficial to ensure that PVC film still has high mechanical properties after long-term use.

[0018] Optionally, the lubricant is a composition of PE wax and stearic acid, and the mass ratio of the PE wax to the stearic acid is (0.8-1):(0.4-0.8).

[0019] By adopting the above technical solution, stearic acid, as an internal lubricant, effectively promotes plasticization and reduces melt viscosity, while PE wax, as an external lubricant, can prevent PVC melt from adhering to equipment. Through the mutual cooperation of the two, an excellent internal and external lubrication synergy effect can be formed during processing, which is conducive to making the PVC film processing process smooth and stable, and also conducive to improving the surface and mechanical properties of PVC film.

[0020] Optionally, the light stabilizer is at least one of ultraviolet absorber UV-P or ultraviolet absorber UV-531.

[0021] By adopting the above technical solutions, it is beneficial to improve the aging resistance of PVC film. Using at least one of the ultraviolet absorbers UV-P or UV-531 can effectively inhibit the breakage and cross-linking of PVC molecular chains, thereby helping to prevent problems such as embrittlement, decreased mechanical properties, and loss of surface gloss of PVC film after long-term use, and can significantly extend the service life of products in outdoor or light-exposed environments.

[0022] Optionally, the pigment or filler is at least one selected from titanium dioxide, carbon black, fast red, phthalocyanine green, phthalocyanine blue, and titanium yellow.

[0023] By adopting the above technical solution, the selected pigments and fillers can not only form a variety of different colors through reasonable matching, but also have good weather resistance and are not easy to age and fade due to long-term use. This is beneficial to improving the appearance performance of PVC film and enabling PVC film to maintain bright colors for a long time.

[0024] Secondly, the preparation method of a high-elasticity PVC film provided in this application adopts the following technical solution: A preparation method of a high-elasticity PVC film includes the following steps: S1, by mass, PVC resin, calcium-zinc stabilizer, POE-coated calcium carbonate, CPE and ACR impact modifier are first added to a high-speed mixer, heated to 95-105℃ and continuously stirred and mixed and dried for 1-2 hours, cooled and then added to a bio-based branched plasticizer, lubricant, light stabilizer and pigments and fillers, and continued to stir and mix evenly to obtain a premix; S2, the premix obtained in step S1 is added to an extruder, and after being fully mixed and extruded by the extruder, it is calendered, stretched, cooled and wound up in sequence to obtain the high-elasticity PVC film.

[0025] By adopting the above technical solution, PVC resin, calcium-zinc stabilizer, POE-coated calcium carbonate, CPE, and ACR impact modifier are pre-mixed at high temperature. This ensures thorough mixing of the raw materials while simultaneously drying them, effectively preventing the influence of moisture in the raw materials on the PVC film melting and mixing process. Furthermore, the production process is simple, requiring no equipment upgrades or modifications, resulting in low improvement costs and facilitating large-scale production in subsequent factories.

[0026] In summary, the technical solution of this application includes at least one of the following beneficial effects: 1. By using bio-based branched plasticizer and POE-coated calcium carbonate to modify PVC film, a PVC film with excellent flexibility and high elasticity, as well as good mechanical strength and tear resistance, can be obtained.

[0027] 2. By using epoxidized soybean oil as raw material, an ester-based bio-based branched plasticizer with a large molecular structure and high branching structure is synthesized. This plasticizer has good migration resistance and long-term flexibility, which helps PVC film maintain good flexibility and elasticity for a long time.

[0028] 3. By using POE-coated calcium carbonate as a reinforcing filler for PVC film, the high-toughness POE layer can not only improve the toughening effect of the filler on the PVC film, but also enable the filler to fully bond with PVC through POE, further improving the reinforcing effect of the filler on the PVC film. Detailed Implementation

[0029] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0030] The epoxidized soybean oil was specifically purchased from Jiangxi Xinhe Chemical Co., Ltd.

[0031] The sulfuric acid / zirconia solid acid catalyst was specifically purchased from Qinzhou Yamei Chemical.

[0032] The calcium carbonate was purchased from Wuquan New Materials Co., Ltd., and the grade was VS-525 ultrafine calcium carbonate.

[0033] The PVC resin powder was specifically purchased from SG-5 PVC resin powder in Erdos.

[0034] The ACR impact modifier was specifically purchased from Kanekazuchi, Japan, with the brand name PA-20.

[0035] The titanium dioxide was purchased from Panzhihua Iron and Steel Group Co., Ltd., and the grade was R-248 rutile titanium dioxide.

[0036] The titanate coupling agent was purchased from Nengde New Materials, specifically the new alkoxy titanate with the brand name TCA-L38.

[0037] The light stabilizers were all purchased from Tianjin Lianlong. Preparation Example

[0038]

Preparation Example 1-1

[0039] In step A1 of this preparation example, the molar ratio of epoxidized soybean oil to methanol is 1:4.2, and catalyst I is specifically selected as sulfuric acid / zirconium dioxide solid acid catalyst, and the amount of sulfuric acid / zirconium dioxide solid acid catalyst added is 1% of the total mass of epoxidized soybean oil and methanol.

[0040] In step A2 of this preparation example, the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid, and ε-caprolactone is 1:4.2:10; the amount of toluene added is 30% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid; catalyst II is specifically stannous octoate, and the amount of catalyst II added is 1.5% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid; the polymerization inhibitor is specifically hydroquinone, and the amount of hydroquinone added is 0.08% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid.

[0041]

Preparation Examples 1-2

[0042] In step A1 of this preparation example, the molar ratio of epoxidized soybean oil to methanol is 1:4.2, and catalyst I is specifically selected as sulfuric acid / zirconium dioxide solid acid catalyst, and the amount of sulfuric acid / zirconium dioxide solid acid catalyst added is 1% of the total mass of epoxidized soybean oil and methanol.

[0043] In step A2 of this preparation example, the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid, and ε-caprolactone is 1:4.5:20; the amount of toluene added is 40% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid; catalyst II is specifically dibutyltin dilaurate, and the amount of catalyst II added is 2% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid; the polymerization inhibitor is specifically hydroquinone, and the amount of hydroquinone added is 0.12% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid.

[0044]

Preparation Examples 1-3

Preparation Example 1

[0045] In this preparation example, the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid and ε-caprolactone is 1:4.2:15.

[0046]

Preparation Examples 1-4

Preparation Example 1

[0047] In this preparation example, the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid and ε-caprolactone is 1:4.2:20.

[0048]

Preparation Example 2-1

[0049] A method for preparing POE-coated calcium carbonate includes the following steps: B1. By mass, calcium carbonate and titanate coupling agent are thoroughly mixed in a high-speed mixer, wherein the mixture is heated to 80°C and stirred at a stirring speed of 1000 r / min for 10 min to uniformly coat the surface of the calcium carbonate with titanate coupling agent, thereby obtaining pretreated calcium carbonate; B2. The pretreated calcium carbonate obtained in step B1 is then thoroughly mixed with POE granules and calcium stearate, and added to an extruder for melt extrusion granulation. After natural cooling and drying, the POE-coated calcium carbonate is obtained.

[0050]

Preparation Example 2-2

Preparation Example 2-1

[0051] In this preparation example, a POE-coated calcium carbonate comprises the following raw materials: 10 kg of POE granules, 5 kg of calcium carbonate, 0.1 kg of calcium stearate, and 0.6 kg of titanate coupling agent. Example

[0052]

Example 1

[0053] In this embodiment, the biological branched plasticizer was specifically prepared according to [Preparation Example 1-1]; the POE-coated calcium carbonate was specifically prepared according to [Preparation Example 2-1]; the lubricant was specifically a composition of PE wax and stearic acid, including 1 kg of PE wax and 0.8 kg of stearic acid; the light stabilizer was specifically selected as the ultraviolet absorber UV-P; and the pigment and filler was specifically titanium dioxide.

[0054] A method for preparing a high-elasticity PVC film includes the following steps: S1, by weight, PVC resin, calcium-zinc stabilizer, POE-coated calcium carbonate, CPE and ACR impact modifier are added to a high-speed mixer, heated to 95°C and continuously stirred and mixed for 2 hours, then cooled and added to a bio-based branched plasticizer, lubricant, light stabilizer and pigments and fillers, and stirred and mixed for 10 minutes to obtain a premix; S2, the premix obtained in step S1 is added to an extruder, fully mixed and extruded through the extruder, and then calendered, stretched, cooled and wound in sequence to obtain the high-elasticity PVC film.

[0055]

Example 2

[0056] In this embodiment, the bio-branched plasticizer was specifically prepared according to [Preparation Examples 1-2]; the POE-coated calcium carbonate was specifically prepared according to [Preparation Example 2-1]; the lubricant was specifically a composition of PE wax and stearic acid, including 1 kg of PE wax and 0.8 kg of stearic acid; the light stabilizer was specifically a composition of ultraviolet absorber UV-P and ultraviolet absorber UV-531, including 0.2 kg of ultraviolet absorber UV-P and 0.2 kg of ultraviolet absorber UV-531; and the pigment and filler was specifically titanium dioxide.

[0057] A method for preparing a high-elasticity PVC film includes the following steps: S1, by weight, PVC resin, calcium-zinc stabilizer, POE-coated calcium carbonate, CPE and ACR impact modifier are added to a high-speed mixer, heated to 105°C and continuously stirred and mixed for 1 hour, then cooled and added to a bio-based branched plasticizer, lubricant, light stabilizer and pigments and fillers, and stirred and mixed for 10 minutes to obtain a premix; S2, the premix obtained in step S1 is added to an extruder, fully mixed and extruded through the extruder, and then calendered, stretched, cooled and wound in sequence to obtain the high-elasticity PVC film.

[0058]

Example 3

Example 1

[0059] In this embodiment, the bio-based branched plasticizer was specifically prepared according to [Preparation Examples 1-3].

[0060]

Example 4

Example 1

[0061] In this embodiment, the bio-based branched plasticizer was specifically prepared according to [Preparation Examples 1-4].

[0062]

Example 5

Example 3

[0063] In this embodiment, the POE-coated calcium carbonate was specifically prepared according to [Preparation Example 2-2]. Comparative Example

[0064]

Comparative Example 1

Example 1

[0065] In this comparative example, epoxidized soybean oil was used to replace the bio-based branched plasticizer in an equal amount.

[0066]

Comparative Example 2

Example 1

[0067] In this comparative example, calcium carbonate was used to replace POE coating calcium carbonate in an equal amount.

[0068]

Comparative Example 3

Example 1

[0069] In this comparative example, coupling-treated calcium carbonate was used to replace POE coating on calcium carbonate in equal amounts. Specifically, the coupling-treated calcium carbonate was prepared by the following method: 30 kg of calcium carbonate and 0.4 kg of titanate coupling agent were thoroughly mixed in a high-speed mixer, heated to 80°C, and stirred at 1000 r / min for 10 min to ensure the titanate coupling agent uniformly coated the surface of the calcium carbonate, thus obtaining the coupling-treated calcium carbonate.

[0070] [Comparative Example 4] A PVC film, differing from [Example 1] in that it does not contain CPE. Performance test data.

[0071] Sample preparation: The sample membrane was prepared according to the formulation and preparation method of each embodiment and comparative example, wherein the membrane thickness was 0.3 mm.

[0072] 1. Mechanical property testing: The test shall be conducted in accordance with section 5.5.3 of GB / T 3830-2008 Soft polyvinyl chloride calendered film and sheet, and the tensile strength (MPa) and elongation at break (%) of each sample shall be recorded.

[0073] 2. Tear resistance: The test shall be conducted in accordance with section 5.5.5 of GB / T 3830-2008 Soft polyvinyl chloride calendered films and sheets. The right-angle tear strength (N) of each test sample shall be calculated and recorded, and the results shall be retained to the nearest integer.

[0074] 3. Long-term performance retention rate: First, conduct an automatic cyclic exposure test according to the provisions of Method A, Cycle No. 1 in Table 3 of GB / T 16422.2-2014 Plastics Laboratory Light Source Exposure Test Method. The exposure time is 500h. After aging, the mechanical properties are tested again, and the tensile strength (MPa) and elongation at break (%) of each sample are recorded after aging.

[0075] Table 1. Partial performance test data of PVC film

[0076] Based on Examples 1 and Comparative Examples 1-4, and the data in Table 1, it can be seen that by using bio-based branched plasticizers and POE-coated calcium carbonate to modify PVC film, a PVC film with excellent flexibility and high elasticity, as well as good mechanical strength and tear resistance, can be obtained.

[0077] As shown in Comparative Example 1 and Comparative Example 1, and their performance test data, compared to epoxidized soybean oil as a traditional PVC plasticizer, the branching modification of epoxidized soybean oil using methanol, 2,2-dimethylolpropionic acid, and ε-caprolactone, resulting in a macromolecular, highly branched ester-based bio-based branched plasticizer, produces PVC films with superior tensile strength, flexibility, and tear resistance. Furthermore, after prolonged aging, the decrease in tensile strength and elongation at break is significantly reduced, contributing to the long-term maintenance of good mechanical properties in the PVC film. This is likely because the bio-based branched plasticizer has more chain segments and a higher free volume, forming multi-point interactions with the PVC molecular chains during processing. This enhances overall compatibility and reduces strength loss due to the addition of the plasticizer, thus achieving a balance between strength and flexibility. Secondly, the long molecular chains and large steric hindrance of bio-based branched plasticizers may further reduce the migration ability of plasticizers, thus the mechanical properties of PVC films do not decrease significantly after long-term aging.

[0078] Furthermore, the addition of bio-based branched plasticizers reduces the radial and transverse tear resistance of PVC films, meaning it reduces the difference in radial and transverse mechanical properties. This may be because the large molecules and highly branched structure of bio-based branched plasticizers easily become physically entangled with multiple PVC molecular chains during flocking, thus forcing the molecular chains to maintain a more random and isotropic state. This, in turn, helps to reduce the difference in radial and transverse mechanical properties of the PVC film, resulting in more uniform overall performance.

[0079] As shown in Comparative Example 1 and Comparative Examples 2-4 and their performance test data, compared with traditional calcium carbonate or calcium carbonate after coupling treatment, POE-coated calcium carbonate can further improve the mechanical properties of PVC film. The decrease in elongation at break of the PVC film after aging is significantly reduced, indicating that it can maintain good flexibility and elasticity for a long time. This may be because POE, as an elastomer, can form a flexible and deformable transition layer on the surface of calcium carbonate during co-extrusion granulation. This not only effectively transfers and disperses stress, which is beneficial to further improving the flexibility of the PVC film, but also allows the POE molecular chains to strongly intertwine and penetrate with the PVC molecular chains, enabling the POE-coated calcium carbonate to fully combine with PVC, which is beneficial to further improving the reinforcing and toughening effect of POE-coated calcium carbonate.

[0080] Furthermore, when the system contains POE-coated calcium carbonate without the addition of CPE, the mechanical properties and aging resistance of the PVC film are significantly reduced. This may be because PVC and POE have poor compatibility, while CPE, as a toughening agent, also acts as a good compatibility agent between PVC and POE. Therefore, only when POE-coated calcium carbonate is added to a PVC formulation system containing CPE can the toughening and strengthening effect of POE-coated calcium carbonate be fully realized.

[0081] Based on Examples 1 and 3-4 and the data in Table 1, it can be seen that as the proportion of ε-caprolactone in the bio-based branched plasticizer increases, the elongation at break of the PVC film also increases, and the increase shows a trend of first large and then slow. However, after long-term aging, the tensile strength and elongation at break of the PVC film decrease more significantly, and the mechanical properties deteriorate more obviously.

[0082] Based on Examples 3 and 5 and the data in Table 1, it can be seen that as the calcium carbonate content in POE-coated calcium carbonate increases, the tensile strength of the subsequently produced PVC film increases, and the effect on the elongation at break and tear resistance of the PVC film is not significant. However, after long-term aging, the elongation at break of the PVC film decreases more significantly, and the deterioration of flexibility and elasticity is more obvious.

[0083] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A highly elastic PVC film, characterized in that: The raw materials include the following parts by weight: PVC resin powder: 100 parts; calcium-zinc stabilizer: 4-6 parts; bio-based branched plasticizer: 40-50 parts; POE-coated calcium carbonate: 5-10 parts; CPE: 8-10 parts; ACR impact modifier: 1-2.5 parts; Lubricant: 1.2-1.8 parts; Light stabilizer: 0.5-0.8 parts; Pigments and fillers: 0.5-3 parts; wherein, the bio-based branched plasticizer is prepared by reaction of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid and ε-caprolactone, and the epoxidized soybean oil-based polyol is specifically prepared by ring-opening reaction of epoxidized soybean oil and methanol.

2. The high-elasticity PVC film according to claim 1, characterized in that: The preparation method of bio-based branched plasticizer includes the following steps: A1. Dissolve methanol in dichloromethane, heat to 60-65℃, add epoxidized soybean oil and catalyst I in proportion, continue heating to 100-105℃, and continue stirring the reaction for 2-3 hours after reaching the target temperature. Then remove catalyst I to terminate the reaction, and remove dichloromethane and methanol by vacuum distillation to obtain epoxidized soybean oil-based polyol; A2. Add the epoxidized soybean oil-based polyol obtained in step A1, 2-dimethylolpropionic acid and toluene to a reaction vessel, and introduce inert gas. The gas is heated to 115-120℃ in an inert atmosphere and preheated for 20-30 minutes. Then, catalyst II and polymerization inhibitor are added under stirring. The temperature is continued to rise to 135-140℃, and the reaction is continued under stirring in an inert atmosphere for more than 12 hours. During this period, water is continuously separated until no obvious water is generated in the water separator to obtain branched polyol. After the branched polyol is cooled to 120-130℃, ε-caprolactone is added and stirred evenly. The temperature is maintained and the reaction is continued under stirring for 6-8 hours. After the reaction is completed, vacuum distillation is performed to obtain bio-based branched plasticizer.

3. The highly elastic PVC film according to claim 2, characterized in that: In step A1, the molar ratio of epoxidized soybean oil to methanol is 1:(4.2-4.5), and the amount of catalyst I added is 0.5-1% of the total mass of epoxidized soybean oil and methanol; in steps A2 and A3, the molar ratio of epoxidized soybean oil-based polyol, 2,2-dimethylolpropionic acid, and ε-caprolactone is 1:(4.5-5):(10-20), the amount of toluene added is 30-40% of the mass of epoxidized soybean oil-based polyol, the amount of catalyst II added is 0.5-1.5% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid, and the amount of polymerization inhibitor added is 0.05-0.1% of the total mass of epoxidized soybean oil-based polyol and 2,2-dimethylolpropionic acid.

4. The high-elasticity PVC film according to claim 3, characterized in that: In step A1, catalyst I is specifically a sulfuric acid / zirconium dioxide solid acid catalyst; in step A2, catalyst II is either stannous octoate or dibutyltin dilaurate, and the polymerization inhibitor is specifically hydroquinone.

5. The high-elasticity PVC film according to claim 1, characterized in that: The preparation method of the POE-coated calcium carbonate includes the following steps: B1, by mass, calcium carbonate and titanate coupling agent are first fully mixed in a high-speed mixer so that the titanate coupling agent is uniformly coated on the surface of calcium carbonate to obtain pretreated calcium carbonate; B2, the pretreated calcium carbonate obtained in step B1 is then fully mixed with POE granules and calcium stearate and added to an extruder for melt extrusion granulation. After natural cooling and drying, the POE-coated calcium carbonate is obtained.

6. The high-elasticity PVC film according to claim 5, characterized in that: The mass ratio of the POE granules, the calcium carbonate, the calcium stearate, and the titanate coupling agent is 100:(30-50):(0.8-1):(4-6).

7. The high-elasticity PVC film according to claim 1, characterized in that: The lubricant is a composition of PE wax and stearic acid, and the mass ratio of the PE wax to the stearic acid is (0.8-1):(0.4-0.8).

8. The high-elasticity PVC film according to claim 1, characterized in that: The light stabilizer is at least one of ultraviolet absorber UV-P or ultraviolet absorber UV-531.

9. A highly elastic PVC film according to claim 1, characterized in that: The pigments and fillers are at least one of titanium dioxide, carbon black, fast red, phthalocyanine green, phthalocyanine blue, and titanium yellow.

10. A method for preparing a highly elastic PVC film, used to prepare the highly elastic PVC film as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. By weight, first add PVC resin, calcium-zinc stabilizer, POE-coated calcium carbonate, CPE and ACR impact modifier to a high-speed mixer, heat to 95-105℃ and continuously stir and mix and dry for 1-2 hours. After cooling, add bio-based branched plasticizer, lubricant, light stabilizer and pigments and fillers, and continue to stir and mix evenly to obtain a premix. S2. Add the premix obtained in step S1 to an extruder, fully mix and extrude through the extruder, and then calender, stretch, cool and wind in sequence to obtain the high-elasticity PVC film.

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