PVC-based thermoplastic dynamic vulcanization material, and preparation method and application thereof

Abstract

This invention belongs to the field of polymer material modification technology, and more specifically relates to a PVC-based thermoplastic dynamic vulcanizing material, its preparation method, and its application. The PVC-based thermoplastic dynamic vulcanizing material provided by this invention is an extremely cold-resistant, low-migration polyvinyl chloride / ethylene-vinyl acetate thermoplastic dynamic vulcanizing material. It uses polyvinyl chloride as the matrix, dioctyl terephthalate and di(2-ethylhexyl) adipate as compound plasticizers, and ethylene-vinyl acetate copolymer as the flexible phase. In-situ dynamic vulcanization of the ethylene-vinyl acetate phase is achieved through organic peroxide crosslinking agents and co-crosslinking agents, thereby constructing a confined crosslinking network and achieving a balance between cold resistance and migration resistance in the flexible PVC material.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, and more specifically relates to a PVC-based thermoplastic dynamic vulcanizate material, its preparation method and application. Background Technology

[0002] Polyvinyl chloride (PVC) is widely used in wire and cable insulation, sheathing, and other flexible products due to its excellent electrical insulation, mechanical properties, chemical resistance, and processing performance. Plasticizers are typically added to impart good flexibility to PVC. However, in low-temperature environments such as high altitudes and frigid conditions, existing flexible PVC materials generally suffer from the following problems: firstly, chain segment movement is restricted at low temperatures, making the material prone to embrittlement; secondly, low-molecular-weight components are prone to migration under thermal contact conditions, affecting the long-term service stability of the material.

[0003] In existing technologies, common methods to improve the low-temperature performance of PVC include increasing the amount of plasticizer, using compound plasticizers, and introducing elastomers for toughening. However, while simply increasing the content of flexible components helps to lower the embrittlement temperature of the material, it often exacerbates the migration of low-molecular-weight components. Although uncrosslinked elastomer phases can improve the ductility of the material, their inhibitory effect on migration behavior is limited, making it difficult to achieve a synergistic improvement in cold resistance and migration resistance.

[0004] Therefore, developing a PVC-based thermoplastic dynamic vulcanizate material that combines excellent cold resistance and low migration characteristics has important practical application significance. Summary of the Invention

[0005] The purpose of this invention is to provide a PVC-based thermoplastic dynamic vulcanizing material, its preparation method, and its application. This invention solves the problems existing in the prior art by providing a cold-resistant, low-migration PVC / ethylene-vinyl acetate thermoplastic dynamic vulcanizing material, thus achieving a balance between cold resistance and migration resistance of flexible PVC materials.

[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention: provides a PVC-based thermoplastic dynamic vulcanizate material, wherein the raw materials, by weight, include: 100 parts polyvinyl chloride resin, 30-70 parts dioctyl terephthalate, 5-20 parts di(2-ethylhexyl) adipate, 2-10 parts stabilizer, 5-30 parts ethylene-vinyl acetate copolymer, 0.1-5 parts organic peroxide crosslinking agent and 0.1-8 parts co-crosslinking agent.

[0007] The PVC-based thermoplastic dynamic vulcanizing material provided by this invention is a cold-resistant, low-migration polyvinyl chloride / ethylene-vinyl acetate thermoplastic dynamic vulcanizing material. It uses polyvinyl chloride as the matrix, dioctyl terephthalate and di(2-ethylhexyl) adipate as compound plasticizers, and ethylene-vinyl acetate copolymer as the flexible phase. In-situ dynamic vulcanization of the ethylene-vinyl acetate phase is achieved through organic peroxide crosslinking agents and co-crosslinking agents, thereby constructing a confined crosslinking network. This maintains excellent low-temperature flexibility while inhibiting the migration of low-molecular-weight components. The material of this invention has a lower embrittlement temperature and a lower thermal contact mass loss rate, making it suitable for the preparation of insulation layers, sheathing layers, and flexible PVC products for wires and cables in high-altitude and cold environments.

[0008] Furthermore, the stabilizer includes at least one of calcium-zinc stabilizer, 6809T stabilizer, and organotin stabilizer.

[0009] Furthermore, the organic peroxide crosslinking agent includes at least one of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and bis-tert-butylperoxide.

[0010] Furthermore, the co-crosslinking agent includes at least one of zinc diacrylate, triallyl isocyanurate, and zinc dimethacrylate.

[0011] The second technical solution of the present invention provides a method for preparing the above-mentioned PVC-based thermoplastic dynamic vulcanizate material, comprising the following steps: Polyvinyl chloride resin, dioctyl terephthalate, di(2-ethylhexyl) adipate, stabilizer and ethylene-vinyl acetate copolymer are mixed and blended to obtain a mixture. After the mixture is premixed, an organic peroxide crosslinking agent and a co-crosslinking agent are added, and the mixture is further kneaded to obtain the premix. The premixed material is pressed into shape to obtain the PVC-based thermoplastic dynamic vulcanized material.

[0012] Furthermore, the premixing treatment is carried out at a temperature of 150-190°C for a time of 1-5 minutes.

[0013] Furthermore, the continued mixing time is 3-15 minutes.

[0014] Furthermore, the pressing process is as follows: preheating at 150-190℃ for 1-5 minutes, then pressing at 5-15MPa pressure for 3-10 minutes, maintaining the pressure and cooling, and then pressing for another 3-10 minutes after cooling.

[0015] The preparation process of this invention involves three steps, including premixing, in-situ dynamic vulcanization mixing, and compression molding.

[0016] The third technical solution of the present invention provides an application of the above-mentioned PVC-based thermoplastic dynamic vulcanizing material in the preparation of insulation layers, sheath layers, and flexible polyvinyl chloride products for high-altitude and cold environments for wires and cables.

[0017] Furthermore, the aforementioned flexible polyvinyl chloride products for cold environments include flexible polyvinyl chloride products used in environments with a temperature not exceeding -60°C.

[0018] The present invention discloses the following technical effects: This invention utilizes a compound plasticizer of dioctyl terephthalate and di(2-ethylhexyl) adipate to improve the low-temperature flexibility of the PVC matrix while maintaining a low migration risk. By introducing an ethylene-vinyl acetate copolymer to construct a flexible dispersed phase, the material's embrittlement temperature can be further reduced. In-situ dynamic vulcanization allows the ethylene-vinyl acetate phase to form a confined cross-linked network, improving the system's topological constraint while maintaining low-temperature energy dissipation capabilities, thereby reducing the migration of low-molecular-weight components. The PVC-based thermoplastic dynamic vulcanization material provided by this invention achieves a synergistic improvement in both cold resistance and migration resistance, making it suitable for flexible PVC products in high-altitude and cold environments. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 SEM images of DOA-10 / DOTP-50 / PVC at different magnifications.

[0020] Figure 2 SEM images of PVC / EVA-20 at different magnifications.

[0021] Figure 3 SEM images of TPV-1 at different magnifications.

[0022] Figure 4 SEM images of TPV-2 at different magnifications.

[0023] Figure 5 SEM images of TPV-3 at different magnifications.

[0024] Figure 6 This is an elemental distribution diagram for DOA-10 / DOTP-50 / PVC.

[0025] Figure 7 This is an elemental distribution diagram for PVC / EVA-20.

[0026] Figure 8 This is an elemental distribution diagram for TPV-1.

[0027] Figure 9 This is an elemental distribution diagram of TPV-2.

[0028] Figure 10 This is an elemental distribution diagram of TPV-3.

[0029] Figure 11 Infrared spectra of different samples.

[0030] Figure 12 Torque rheological curves for different samples.

[0031] Figure 13 This is a schematic diagram showing the mechanical properties of different samples under normal temperature conditions.

[0032] Figure 14 This is a schematic diagram showing the mechanical properties of different samples under low-temperature conditions. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0037] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0038] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products.

[0039] The polyvinyl chloride resin was purchased from Shandong Lanfan Medical Co., Ltd. Dioctyl terephthalate was purchased from Sinopharm Chemical Reagent Co., Ltd. Di(2-ethylhexyl) adipic acid was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. The ethylene-vinyl acetate copolymer was purchased from DuPont. Stabilizer 6809T was purchased from Shenzhen Zhihai Industrial Co., Ltd. 2,5-Dimethyl-2,5-bis(tert-butylperoxy)hexane was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Triallyl isocyanurate was purchased from Shandong Keyuan Biochemical Co., Ltd.

[0040] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0041] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0042] Example 1 The preparation steps of PVC-based thermoplastic dynamic vulcanizates include: S1. Prepare the following parts by weight of raw materials: 100 parts polyvinyl chloride resin, 50 parts dioctyl terephthalate, 10 parts di(2-ethylhexyl) adipate, 5 parts stabilizer (6809T stabilizer), 20 parts ethylene-vinyl acetate copolymer, 0.2 parts organic peroxide crosslinking agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.2 parts co-crosslinking agent (tracene propyl isocyanurate).

[0043] S2. Mix polyvinyl chloride resin, dioctyl terephthalate, di(2-ethylhexyl) adipate, stabilizer and ethylene-vinyl acetate copolymer, premix at 170°C for 5 min, then add organic peroxide crosslinking agent and co-crosslinking agent, continue mixing for 15 min, and then press to obtain PVC-based thermoplastic dynamic vulcanized material, denoted as TPV-1. The compression molding process is as follows: preheat at 180℃ for 5 minutes, then press at 15MPa pressure for 10 minutes, keep the pressure constant and cool, and continue pressing for 10 minutes after cooling to room temperature.

[0044] Example 2 The preparation steps of PVC-based thermoplastic dynamic vulcanizates include: S1. Prepare the following parts by weight of raw materials: 100 parts polyvinyl chloride resin, 50 parts dioctyl terephthalate, 10 parts di(2-ethylhexyl) adipate, 5 parts stabilizer (6809T stabilizer), 20 parts ethylene-vinyl acetate copolymer, 0.35 parts organic peroxide crosslinking agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.35 parts co-crosslinking agent (triallyl isocyanurate).

[0045] S2. Same as in Example 1, the obtained PVC-based thermoplastic dynamic vulcanizing material is denoted as TPV-2.

[0046] Example 3 The preparation steps of PVC-based thermoplastic dynamic vulcanizates include: S1. Prepare the following parts by weight of raw materials: 100 parts polyvinyl chloride resin, 50 parts dioctyl terephthalate, 10 parts di(2-ethylhexyl) adipate, 5 parts stabilizer (6809T stabilizer), 20 parts ethylene-vinyl acetate copolymer, 0.5 parts organic peroxide crosslinking agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.5 parts co-crosslinking agent (triallyl isocyanurate).

[0047] S2. Same as in Example 1, the obtained PVC-based thermoplastic dynamic vulcanizing material is denoted as TPV-3.

[0048] Comparative Example 1 Preparation of basic plasticized PVC film: S1. Prepare the following parts by weight of raw materials: 100 parts polyvinyl chloride resin, 50 parts dioctyl terephthalate, 10 parts di(2-ethylhexyl) adipate, and 5 parts stabilizer (6809T stabilizer).

[0049] S2. After mixing polyvinyl chloride resin, dioctyl terephthalate, di(2-ethylhexyl) adipate and stabilizer evenly, the mixture is kneaded at 150°C for 5 minutes, and then pressed to obtain a basic plasticized PVC film, denoted as DOA-10 / DOTP-50 / PVC. The pressing and molding process is the same as in Example 1.

[0050] Comparative Example 2 Preparation of uncrosslinked PVC / EVA blend films: S1. Prepare the following parts by weight of raw materials: 100 parts polyvinyl chloride resin, 50 parts dioctyl terephthalate, 10 parts di(2-ethylhexyl) adipate, 5 parts stabilizer (6809T stabilizer), and 20 parts ethylene-vinyl acetate copolymer.

[0051] S2. After uniformly mixing polyvinyl chloride resin, dioctyl terephthalate, di(2-ethylhexyl) adipate, ethylene-vinyl acetate copolymer and stabilizer, the mixture is kneaded at 170°C for 5 minutes and then pressed to obtain an uncrosslinked PVC / EVA blend film, denoted as PVC / EVA-20. The pressing and molding process is the same as in Example 1.

[0052] Test case Figure 1 SEM images of DOA-10 / DOTP-50 / PVC at different magnifications.

[0053] Figure 2 SEM images of PVC / EVA-20 at different magnifications.

[0054] Figure 3 SEM images of TPV-1 at different magnifications.

[0055] Figure 4 SEM images of TPV-2 at different magnifications.

[0056] Figure 5 SEM images of TPV-3 at different magnifications.

[0057] Figure 6 This is an elemental distribution diagram for DOA-10 / DOTP-50 / PVC.

[0058] Figure 7 This is an elemental distribution diagram for PVC / EVA-20.

[0059] Figure 8 This is an elemental distribution diagram for TPV-1.

[0060] Figure 9 This is an elemental distribution diagram of TPV-2.

[0061] Figure 10 This is an elemental distribution diagram of TPV-3.

[0062] Figure 11 Infrared spectra of different samples.

[0063] The samples obtained from the examples and comparative examples were subjected to low-temperature embrittlement temperature, contact migration resistance and mechanical property tests, respectively.

[0064] Low-temperature embrittlement temperature: According to GB / T 5470-2008, the embrittlement temperature of different PVC films is tested using a DC2-B type low-temperature embrittlement impact tester. The temperature at which the sample breakage rate reaches 50% is the embrittlement temperature. The dimensions of the sample strip are 2.5 mm wide, 20 mm long, and 2 mm thick.

[0065] Contact migration resistance: Migration resistance tests were conducted using an oven according to ISO 177:2016(E). The test sample diameter was 50 mm, the thickness was 1 mm, and the test temperature was 70℃. Three samples were tested simultaneously for each group, and the average value was taken as the test result.

[0066] Test results show that the embrittlement temperature of DOA-10 / DOTP-50 / PVC is approximately -43.5℃; the embrittlement temperature of PVC / EVA-20 is approximately -59.5℃; and the embrittlement temperatures of TPV-1, TPV-2, and TPV-3 are approximately -60.0℃, -61.0℃, and -59.5℃, respectively. In the contact migration resistance test, the mass loss rate of DOA-10 / DOTP-50 / PVC after 5 days is approximately 3.43%, that of PVC / EVA-20 is approximately 2.38%, and that of TPV-2 is approximately 2.18%. These results indicate that the present invention, through in-situ dynamic vulcanization to construct a restricted crosslinking network, can further reduce the migration of low-molecular-weight components while maintaining excellent low-temperature flexibility.

[0067] Mechanical properties: The prepared cold-resistant PVC film was cut into dumbbell-shaped strips with a gauge length of 20 mm, a width of 4 mm, and a total length of 75 mm. Tensile tests were performed on the prepared dumbbell-shaped strips using an electronic universal tensile testing machine (Shenzhen WanCe Testing Equipment Co., Ltd.). The tensile rate was selected as 250 mm / min, and at least 5 strips were tested for each group of samples. The average value was taken as the tensile property data.

[0068] In-situ low-temperature tensile tests were conducted using an LS-2 low-temperature tensile tester (Changshu Environmental Testing Equipment Co., Ltd.) according to section 8.3 of GB / T 2951.14-2008. The preparation of the specimens was consistent with that of the dumbbell-shaped specimens prepared for room-temperature tensile testing. Three specimens were tested simultaneously for each group of samples, and the average value was taken as the low-temperature tensile data at -40℃.

[0069] The detailed test results are shown in Table 1: Table 1 Table 1 shows that, compared to Comparative Example 1, the brittle fracture temperature of Example 2 decreased from -43.5℃ to -61.0℃, and the 5-day migration rate decreased from 3.43% to 2.18%.

[0070] Figure 12 Torque rheological curves for different samples.

[0071] Figure 13 This is a schematic diagram showing the mechanical properties of different samples under normal temperature conditions.

[0072] Figure 14 This is a schematic diagram showing the mechanical properties of different samples under low-temperature conditions.

[0073] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0074] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A PVC-based thermoplastic dynamic vulcanizate, characterized in that, By weight, the raw materials include: 100 parts polyvinyl chloride resin, 30-70 parts dioctyl terephthalate, 5-20 parts di(2-ethylhexyl) adipate, 2-10 parts stabilizer, 5-30 parts ethylene-vinyl acetate copolymer, 0.1-5 parts organic peroxide crosslinking agent and 0.1-8 parts co-crosslinking agent.

2. The PVC-based thermoplastic dynamic vulcanizate as described in claim 1, characterized in that, The stabilizer includes at least one of calcium-zinc stabilizer, 6809T stabilizer, and organotin stabilizer.

3. The PVC-based thermoplastic dynamic vulcanizate as described in claim 1, characterized in that, The organic peroxide crosslinking agent includes at least one of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane and di-tert-butylperoxide.

4. The PVC-based thermoplastic dynamic vulcanizate as described in claim 1, characterized in that, The co-crosslinking agent includes at least one of zinc diacrylate, triallyl isocyanurate, and zinc dimethacrylate.

5. A method for preparing a PVC-based thermoplastic dynamic vulcanizate material according to any one of claims 1-4, characterized in that the step... include: Polyvinyl chloride resin, dioctyl terephthalate, di(2-ethylhexyl) adipate, stabilizer and ethylene-vinyl acetate copolymer are mixed and blended to obtain a mixture. After the mixture is premixed, an organic peroxide crosslinking agent and a co-crosslinking agent are added, and the mixture is further kneaded to obtain the premix. The premixed material is pressed into shape to obtain the PVC-based thermoplastic dynamic vulcanized material.

6. The preparation method according to claim 5, characterized in that, The premixing process is carried out at a temperature of 150-190℃ for 1-5 minutes.

7. The preparation method according to claim 5, characterized in that, The mixing time is 3-15 minutes.

8. The preparation method according to claim 5, characterized in that, The pressing process is as follows: preheat at 150-190℃ for 1-5 minutes, then press at 5-15MPa pressure for 3-10 minutes, keep the pressure constant and cool, and continue pressing for 3-10 minutes after cooling.

9. The application of the PVC-based thermoplastic dynamic vulcanizing material according to any one of claims 1-4 in the preparation of insulation layers, sheath layers, and flexible polyvinyl chloride products for cold environments for wires and cables.

10. The application as described in claim 9, characterized in that, The aforementioned flexible polyvinyl chloride products for cold environments include flexible polyvinyl chloride products used in environments with a temperature not exceeding -60°C.

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