A low-temperature-resistant PVC / SEBS modified material and its preparation method

Abstract

The present invention discloses a low-temperature-resistant PVC / SEBS modified material and its preparation method, belonging to the field of polymer materials technology. The PVC / SEBS modified material comprises the following raw materials in parts by weight: 80-100 parts PVC, 20-40 parts SEBS, 5-20 parts plasticizer, 6-10 parts cold-resistant agent, 2-4 parts flame retardant, 5-8 parts antioxidant, 2-3 parts stabilizer, and 3-5 parts lubricant. The PVC / SEBS modified material prepared by the present invention exhibits excellent cold resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a low-temperature-resistant PVC / SEBS modified material and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC), a widely used general-purpose plastic, boasts advantages such as low cost, good processability, high chemical stability, and excellent mechanical strength. It plays a crucial role in numerous industries, including construction, packaging, and electronics. However, PVC suffers from a significant drawback: poor low-temperature resistance. When the temperature drops below a certain level, PVC gradually transitions from a ductile state to a brittle state, manifesting as low-temperature brittleness. This low-temperature brittleness is primarily due to its molecular structure. The presence of a large number of polar chlorine atoms in the PVC molecular chain creates strong intermolecular forces, restricting the movement of molecular segments. At low temperatures, this increased difficulty significantly reduces the material's ability to dissipate internal energy and dramatically weakens its resistance to external impact or deformation. Styrene-ethylene / butylene-styrene block copolymer (SEBS), a new type of thermoplastic elastomer, exhibits excellent flexibility, making it an ideal choice for PVC modification. However, PVC and SEBS are materials of different polarities, resulting in poor compatibility. Direct blending presents several challenges. Phase separation can occur in low-temperature environments, hindering the material's full cold resistance and limiting improvements in low-temperature impact strength and toughness. Furthermore, while the addition of traditional plasticizers can improve PVC's flexibility and processing properties, these plasticizers can migrate at low temperatures, reducing the material's cold resistance.

[0003] Chinese invention patent publication number CN110511506A discloses a low-volatile PVC modified material and a preparation method thereof. The low-volatile PVC modified material comprises the following raw material components in parts by weight: 100 parts of PVC resin powder, 40-70 parts of butadiene-type thermoplastic polyurethane (PU(HTPB)), 50-100 parts of styrene-ethylene / butylene-styrene block copolymer (SEBS), 50-75 parts of cycloalkyl oil, 12-20 parts of SEBS maleic anhydride graft (SEBS-g-MAH), 3-5 parts of calcium zinc stabilizer, 1-2 parts of lubricant, and 1-2 parts of antioxidant. The low-volatile PVC modified material obtained by this invention has excellent hardness and tensile strength, but its cold resistance is poor. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a low-temperature resistant PVC / SEBS modified material and a preparation method thereof.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A low-temperature-resistant PVC / SEBS modified material comprises the following raw materials in parts by weight:

[0007] PVC: 80-100 parts, SEBS: 20-40 parts, plasticizer: 5-20 parts, cold-resistant agent: 6-10 parts, flame retardant: 2-4 parts, antioxidant: 5-8 parts, stabilizer: 2-3 parts, lubricant: 3-5 parts;

[0008] The plasticizer is prepared by the following method:

[0009] S1: 1,3-bis((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propan-2-amine reacts with polypropylene glycol diglycidyl ether to form a heteropentane compound;

[0010] S2: The heteropentyl compound is hydrolyzed under the action of hydrochloric acid to form an eight-arm hydroxy compound;

[0011] S3: The eight-arm hydroxy compound reacts with stearic acid in the presence of p-toluenesulfonic acid to generate a plasticizer.

[0012] In step S1, the mass ratio of 1,3-bis((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propan-2-amine to polypropylene glycol diglycidyl ether is (2-2.5):1.

[0013] In the step S2, the mass ratio of the heteropentyl ring compound to the hydrochloric acid is 4:(3-3.5).

[0014] In step S3, the feeding mass ratio of the eight-arm hydroxy compound and stearic acid is 1:(3-5).

[0015] The cold-resistant agent is prepared by the following method:

[0016] A1: Pentaerythritol reacts with 3,6-dimethyl-1,4-dioxane-2,5-dione under the catalysis of stannous octoate to form a four-arm star-shaped compound;

[0017] A2: A four-arm star-shaped compound reacts with maleimide-octapolyethylene glycol-carboxylic acid in the presence of p-toluenesulfonic acid to generate a cold-resistant agent.

[0018] In the step A1, the mass ratio of pentaerythritol to 3,6-dimethyl-1,4-dioxane-2,5-dione is 1:20.

[0019] In the step A2, the mass ratio of the four-arm star compound to maleimide-octapolyethylene glycol-carboxylic acid is 1:1.5.

[0020] The flame retardant is one of tributyl phosphate, tri(2-ethylhexyl) phosphate, and tri(2-chloroethyl) phosphate; the antioxidant is one of N-phenyl-α-aniline, N-phenyl-β-naphthylamine, and N-phenyl-N'-isopropyl-p-phenylenediamine; and the stabilizer is one of JX-181 organic tin heat stabilizer, JX-107 reverse ester tin heat stabilizer, and JT-101 mercaptan antimony heat stabilizer.

[0021] The lubricant is one of fatty acid, fatty acid ester and fatty acid amide.

[0022] A method for preparing a low-temperature-resistant PVC / SEBS modified material comprises the following steps:

[0023] (1): Weigh by weight: PVC: 80-100 parts, SEBS: 20-40 parts, plasticizer: 5-20 parts, cold-resistant agent: 6-10 parts, flame retardant: 2-4 parts, antioxidant: 5-8 parts, stabilizer: 2-3 parts, lubricant: 3-5 parts;

[0024] (2): Add all components into a high-speed mixer and mix them. Then, introduce the mixture into a twin-screw extruder for extrusion and granulation, air-cool and sieve to obtain the PVC / SEBS modified material.

[0025] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0026] (1) The long stearate chain in the plasticizer prepared by the present invention enhances the low-temperature mobility of the molecular chain, and the eight-arm branched structure disperses stress and inhibits crack propagation. The toughness of the composite material is enhanced through the synergistic effect of the eight-arm branched structure and the long stearate chain.

[0027] (2) The cold-resistant agent prepared by the present invention disperses stress through the three-dimensional cross-linked network of the four-arm star-shaped polyester core, inhibiting low-temperature brittle fracture; introducing octapolyethylene glycol segments to enhance the low-temperature flexibility of the molecular chain; and improving the impact resistance and crack resistance of the material at extremely low temperatures. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0029] Example 1 Preparation of plasticizer:

[0030] S1: Under nitrogen protection, 300g toluene, 40g 1,3-bis((2,2-dimethyl-1,3-dioxolane-4-yl)methoxy)propan-2-amine, and 20g polypropylene glycol diglycidyl ether were added to the reactor, stirred, heated to 80°C, reacted for 6h, cooled to 60°C, and 45g 48wt% sodium hydroxide solution was slowly added dropwise for 20min. After the addition was completed, the reaction was continued at 60°C for 2h. After the reaction was completed, the reaction was cooled to room temperature and 1M dilute hydrochloric acid solution was slowly added until the pH value of the reaction solution was neutral; the reaction was allowed to stand and separate, the aqueous phase was separated, and the organic phase was retained. The reaction was distilled under reduced pressure at 60°C for 3h, and then 100ml saturated sodium chloride solution was added for washing, and the reaction was repeated three times. The heterocyclic compound was obtained. The reaction equation is shown as follows:

[0031] .

[0032] S2: 400 g of deionized water and 80 g of the heterocyclic compound were added to the reactor, followed by 100 g of 15 wt% dilute hydrochloric acid, stirred and mixed, and the temperature was raised to reflux for 2 h. 10 wt% sodium hydroxide solution was added to adjust the pH to neutral, filtered, and washed with 100 g of deionized water, repeated three times, and dried under vacuum at 60 ° C for 10 h to obtain an eight-arm hydroxy compound; the reaction equation is shown as follows:

[0033] .

[0034] S3: Under nitrogen protection, 300 g of toluene, 20 g of the eight-arm hydroxy compound, and 60 g of stearic acid were added to the reactor, and the temperature was raised to 80°C. Then, 5 g of p-toluenesulfonic acid was added and the reaction was carried out for 6 h (a water separator was used to remove the generated water during the reaction). The temperature was then cooled to room temperature, and a saturated sodium bicarbonate solution was slowly added to adjust the pH to neutral. The mixture was stirred thoroughly for 30 min, and the mixture was allowed to stand for stratification. The organic phase was transferred to a rotary evaporator and distilled under reduced pressure at 60°C for 4 h to obtain a plasticizer. The reaction equation is shown below:

[0035] .

[0036] Example 2 Preparation of plasticizer:

[0037] S1: Under nitrogen protection, 300g toluene, 45g 1,3-bis((2,2-dimethyl-1,3-dioxolane-4-yl)methoxy)propan-2-amine, and 20g polypropylene glycol diglycidyl ether were added to the reactor, stirred, heated to 90°C, reacted for 5h, cooled to 60°C, and 45g 48wt% sodium hydroxide solution was slowly added dropwise for 20min. After the addition was completed, the reaction was continued at 60°C for 1.5h. After the reaction was completed, it was cooled to room temperature and 1M dilute hydrochloric acid solution was slowly added until the pH value of the reaction solution was neutral; the mixture was allowed to stand and separate, the aqueous phase was separated, and the organic phase was retained. It was distilled under reduced pressure at 60°C for 3h, then washed with 100ml saturated sodium chloride solution, repeated three times, and vacuum dried at 60°C for 12h to obtain a heterocyclic compound.

[0038] S2: Add 400 g of deionized water and 80 g of the heterocyclic compound to the reactor, then add 110 g of 15 wt% dilute hydrochloric acid, stir and mix, heat to reflux for 3 h, add 10 wt% sodium hydroxide solution to adjust the pH to neutral, filter, wash with 100 g of deionized water, repeat three times, and dry in vacuo at 60 ° C for 10 h to obtain an eight-arm hydroxy compound.

[0039] S3: Under nitrogen protection, add 300g toluene, 20g eight-arm hydroxy compound, and 80g stearic acid to the reactor, raise the temperature to 90°C, and then add 5g p-toluenesulfonic acid. After reacting for 5h (a water separator is used to remove the generated water during the reaction), cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to neutral, stir thoroughly for 30min, let stand to separate, transfer the organic phase to a rotary evaporator, and distill under reduced pressure at 60°C for 4h to obtain a plasticizer.

[0040] Example 3 Preparation of plasticizer:

[0041] S1: Under nitrogen protection, 300g toluene, 50g 1,3-bis((2,2-dimethyl-1,3-dioxolane-4-yl)methoxy)propan-2-amine, and 20g polypropylene glycol diglycidyl ether were added to the reactor, stirred, heated to 100°C, reacted for 4h, cooled to 60°C, and 45g 48wt% sodium hydroxide solution was slowly added dropwise for 20min. After the addition was completed, the reaction was continued at 60°C for 1h. After the reaction was completed, the reaction was cooled to room temperature and 1M dilute hydrochloric acid solution was slowly added until the pH value of the reaction solution was neutral; the reaction was allowed to stand and separate, the aqueous phase was separated, and the organic phase was retained. The reaction was distilled under reduced pressure at 60°C for 3h, and then 100ml saturated sodium chloride solution was added for washing. The reaction was repeated three times and vacuum dried at 60°C for 12h to obtain a heterocyclic compound.

[0042] S2: Add 400 g of deionized water and 80 g of the heterocyclic compound to the reactor, then add 120 g of 15 wt% dilute hydrochloric acid, stir and mix, heat to reflux for 4 h, add 10 wt% sodium hydroxide solution to adjust the pH to neutral, filter, wash with 100 g of deionized water, repeat three times, and dry in vacuo at 60 ° C for 10 h to obtain an eight-arm hydroxy compound.

[0043] S3: Under nitrogen protection, add 300g toluene, 20g eight-arm hydroxy compound, and 100g stearic acid to the reactor, raise the temperature to 100℃, then add 5g p-toluenesulfonic acid, react for 4h (use a water separator to remove the generated water during the reaction), cool to room temperature, slowly add saturated sodium bicarbonate solution to adjust the pH to neutral, stir thoroughly for 30min, let stand to separate, transfer the organic phase to a rotary evaporator, and distill under reduced pressure at 60℃ for 4h to obtain a plasticizer.

[0044] Example 4 Preparation of cold-resistant agent:

[0045] A1: Under nitrogen protection, 800 g of DMF, 10 g of pentaerythritol, and 200 g of 3,6-dimethyl-1,4-dioxane-2,5-dione were added to a reactor and stirred to mix. The temperature was raised to 120°C and stirred for 15 min. Then, 8 g of stannous octoate catalyst was added and reacted for 18 h. The mixture was cooled to room temperature and distilled under reduced pressure at 60°C for 2 h to obtain a crude product. The crude product was added to 500 ml of chloroform and stirred to mix. Then, 200 ml of cold methanol was added and the mixture was allowed to stand to precipitate. The mixture was then washed three times with 150 ml of methanol each time and dried under vacuum at 60°C for 5 h to obtain a four-arm star compound. The reaction equation is shown below:

[0046] .

[0047] A2: Under nitrogen protection, 300 g of toluene, 20 g of the four-arm star compound, and 30 g of maleimide-octapolyethylene glycol-carboxylic acid were added to the reactor. The temperature was raised to 90°C, and then 5 g of p-toluenesulfonic acid was added. After reacting for 5 h (a water separator was used to remove the generated water during the reaction), the temperature was cooled to room temperature, and a saturated sodium bicarbonate solution was slowly added to adjust the pH to neutral. The mixture was stirred thoroughly for 30 min, and the mixture was allowed to stand for stratification. The organic phase was transferred to a rotary evaporator and distilled under reduced pressure at 60°C for 4 h to obtain a cold-resistant agent. The reaction equation is shown below:

[0048] .

[0049] Example 5 Preparation of PVC / SEBS modified material:

[0050] (1): Weigh 800g of PVC, 200g of SEBS, 50g of plasticizer (prepared in Example 1), 60g of cold-resistant agent (prepared in Example 4), 20g of flame retardant (tributyl phosphate), 50g of antioxidant (N-phenyl-α-aniline), 20g of stabilizer (JX-181 organic tin heat stabilizer), and 30g of lubricant (fatty acid).

[0051] (2): Add all components into a high-speed mixer and mix them. The mixing temperature is 110℃, the mixing speed is 200r / min, and the mixing time is 20min. Then, the mixture is introduced into a twin-screw extruder for extrusion and granulation. The screw speed of the screw extruder is 20r / s. The temperature of the conveying section of the twin-screw extruder is 120℃, the temperature of the melting section is 160℃, the temperature of the mixing section is 170℃, and the temperature of the homogenizing section is 145℃. The mixture is air-cooled and sieved to obtain the PVC / SEBS modified material.

[0052] Example 6 Preparation of PVC / SEBS modified material:

[0053] (1): Weigh PVC: 900g, SEBS: 300g, plasticizer (prepared in Example 2): 150g, cold-resistant agent (prepared in Example 4): 80g, flame retardant (tri(2-ethylhexyl) phosphate): 30g, antioxidant (N-phenyl-β-naphthylamine): 60g, stabilizer (JX-107 reverse ester tin heat stabilizer): 25g, lubricant (fatty acid ester): 40g;

[0054] (2): Add all components into a high-speed mixer and mix them. The mixing temperature is 120℃, the mixing speed is 250r / min, and the mixing time is 25min. Then, the mixture is introduced into a twin-screw extruder for extrusion and granulation. The screw speed of the screw extruder is 20r / s. The temperature of the conveying section of the twin-screw extruder is 120℃, the temperature of the melting section is 160℃, the temperature of the mixing section is 170℃, and the temperature of the homogenizing section is 145℃. The mixture is air-cooled and sieved to obtain the PVC / SEBS modified material.

[0055] Example 7 Preparation of PVC / SEBS modified material:

[0056] (1): Weigh PVC: 1000g, SEBS: 400g, plasticizer (prepared in Example 3): 200g, cold-resistant agent (prepared in Example 4): 100g, flame retardant (tris(2-chloroethyl) phosphate): 40g, antioxidant (N-phenyl-N'-isopropyl-p-phenylenediamine): 80g, stabilizer (JT-101 antimony mercaptan heat stabilizer): 30g, lubricant (fatty acid amide): 50g;

[0057] (2): Add all components into a high-speed mixer and mix them at a mixing temperature of 130°C, a mixing speed of 300 r / min, and a mixing time of 30 min. Then, introduce the mixture into a twin-screw extruder for extrusion granulation. The screw speed of the screw extruder is 20 r / s, the temperature of the conveying section of the twin-screw extruder is 120°C, the temperature of the melting section is 160°C, the temperature of the mixing section is 170°C, and the temperature of the homogenizing section is 145°C. Air-cooled and sieved, PVC / SEBS modified material is obtained.

[0058] Comparative Example 1

[0059] A low-temperature-resistant PVC / SEBS modified material, the raw material composition and process are basically the same as those in Example 6, except that the plasticizer is replaced by an equal weight of a plasticizer prepared by the following method:

[0060] The preparation method of the plasticizer is basically the same as that of Example 2, except that the 1,3-bis((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propan-2-amine in step S1 is replaced by an equal weight of 2,2-dimethyl-1,3-dioxolane-4-methylamine.

[0061] Comparative Example 2

[0062] A low-temperature-resistant PVC / SEBS modified material, the raw material composition and process are basically the same as those in Example 6, except that the plasticizer is replaced by an equal weight of a plasticizer prepared by the following method:

[0063] The preparation method of the plasticizer is basically the same as that of Example 2, except that the polypropylene glycol diglycidyl ether in step S1 is replaced by an equal weight of 1,6-hexanediol diglycidyl ether.

[0064] Comparative Example 3

[0065] A low-temperature-resistant PVC / SEBS modified material, the raw material composition and process are basically the same as those in Example 6, except that the plasticizer is replaced by an equal weight of a plasticizer prepared by the following method:

[0066] The preparation method of the plasticizer is basically the same as that of Example 2, except that the stearic acid in step S3 is replaced by an equal weight of hexanoic acid.

[0067] Comparative Example 4

[0068] A low-temperature-resistant PVC / SEBS modified material, the raw material composition and process are basically the same as those in Example 6, except that the cold-resistant agent is replaced by an equal weight of a cold-resistant agent prepared by the following method:

[0069] The preparation method of the cold-resistant agent is basically the same as that of Example 4, except that the pentaerythritol in step A1 is replaced by an equal weight of dipentaerythritol.

[0070] Comparative Example 5

[0071] A low-temperature-resistant PVC / SEBS modified material, the raw material composition and process are basically the same as those in Example 6, except that the cold-resistant agent is replaced by an equal weight of a cold-resistant agent prepared by the following method:

[0072] The preparation method of the cold-resistant agent is basically the same as that of Example 4, except that the maleimide-octapolyethylene glycol-carboxylic acid in step A2 is replaced by an equal weight of maleimide-tetrapolyethylene glycol-carboxylic acid.

[0073] Comparative Example 6

[0074] A low-temperature-resistant PVC / SEBS modified material, the raw material composition and process are basically the same as those in Example 6, except that the cold-resistant agent is replaced by an equal weight of a cold-resistant agent prepared by the following method:

[0075] The preparation method of the cold-resistant agent is basically the same as that of Example 4, except that the maleimide-octapolyethylene glycol-carboxylic acid in step A2 is replaced by an equal weight of oleic acid.

[0076] The brand of PVC used in the examples and comparative examples of the present application is SG-5, purchased from Shanghai Chlor-Alkali Chemical Co., Ltd.; the model of SEBS used is YH-503, produced by Baling Petrochemical Co., Ltd.; the molecular weight of polypropylene glycol diglycidyl ether is 300, produced by Wuhan Shuer Biotechnology Co., Ltd.

[0077] The PVC / SEBS modified materials prepared in the examples and comparative examples were subjected to hardness, low-temperature brittleness and notched impact strength tests.

[0078] The hardness was tested in accordance with GB / T531.1-2008 "Rubber, vulcanized or thermoplastic — Indentation hardness test method — Part 1: Shore hardness" using a Type A durometer. The low-temperature brittleness was tested in accordance with GB / T15256-2014 using a Type B strip specimen. The notched impact strength was tested in accordance with GB / T1843-2008. The test results are shown in Table 1.

[0079] Table 1 PVC / SEBS modified material performance test table

[0080]

[0081] It can be seen from Examples 5, 6 and 7 in Table 1 that the PVC / SEBS modified material prepared by the present invention has excellent cold resistance.

[0082] The plasticizer prepared by the present invention contains a large number of ester groups, which can form dipole-dipole interactions with the chlorine atoms on the PVC chain, weakening the van der Waals and dipole forces between the PVC molecular chains, lowering the material's glass transition temperature, and improving its flexibility. The long-chain alkyl introduced by stearic acid is hydrophobic and can insert between PVC molecular chains, increasing free volume, reducing chain segment entanglement, and promoting chain segment movement. The branched structure provides more physical entanglement points with the PVC chain, improving the compatibility between PVC and SEBS, and reducing plasticizer migration.

[0083] The cold-resistant agent prepared by this invention features a four-arm star-shaped structure with pentaerythritol as its core. This structure effectively disperses external stress and inhibits rigid fracture of the molecular chain at low temperatures, thereby improving the material's impact resistance and cracking resistance. The high flexibility and hydrophilicity of the grafted octaethylene glycol chains significantly lower the material's glass transition temperature, enhancing the molecular chain's mobility at low temperatures and preventing brittle fracture.

[0084] In Comparative Example 2, the linear alkane structure of 1,6-hexanediol (containing only two ether oxygen bonds) restricts molecular chain motion, resulting in poor low-temperature brittleness. In Comparative Example 5, the shorter molecular chain length of tetraethylene glycol limits molecular chain motion at low temperatures, resulting in reduced resistance to brittle fracture.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in this field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A low-temperature resistant PVC / SEBS modified material, characterized in that: The composition comprises the following raw materials in parts by weight: PVC: 80-100 parts, SEBS: 20-40 parts, plasticizer: 5-20 parts, cold-resistant agent: 6-10 parts, flame retardant: 2-4 parts, antioxidant: 5-8 parts, stabilizer: 2-3 parts, lubricant: 3-5 parts; The plasticizer is prepared by the following method: S1: 1,3-bis((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propan-2-amine reacts with polypropylene glycol diglycidyl ether to form a heteropentane compound; S2: The heteropentyl compound is hydrolyzed under the action of hydrochloric acid to form an eight-arm hydroxy compound; S3: The eight-arm hydroxy compound reacts with stearic acid under the action of p-toluenesulfonic acid to form a plasticizer; The cold-resistant agent is prepared by the following method: A1: Pentaerythritol reacts with 3,6-dimethyl-1,4-dioxane-2,5-dione under the catalysis of stannous octoate to form a four-arm star-shaped compound; A2: A four-arm star-shaped compound reacts with maleimide-octapolyethylene glycol-carboxylic acid in the presence of p-toluenesulfonic acid to generate a cold-resistant agent.

2. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: In step S1, the mass ratio of 1,3-bis((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propan-2-amine to polypropylene glycol diglycidyl ether is (2-2.5):

1.

3. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: In step S2, the mass ratio of the heteropentyl ring compound to the hydrochloric acid is 4:(5-6).

4. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: In step S3, the feeding mass ratio of the eight-arm hydroxy compound and stearic acid is 1:(3-5).

5. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: In the step A1, the mass ratio of pentaerythritol to 3,6-dimethyl-1,4-dioxane-2,5-dione is 1:

20.

6. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: In the step A2, the mass ratio of the four-arm star compound to maleimide-octapolyethylene glycol-carboxylic acid is 1:1.

5.

7. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: The flame retardant is one of tributyl phosphate, tri(2-ethylhexyl) phosphate, and tri(2-chloroethyl) phosphate; the antioxidant is one of N-phenyl-α-aniline, N-phenyl-β-naphthylamine, and N-phenyl-N'-isopropyl-p-phenylenediamine; and the stabilizer is one of JX-181 organic tin heat stabilizer, JX-107 reverse ester tin heat stabilizer, and JT-101 mercaptan antimony heat stabilizer.

8. The low-temperature resistant PVC / SEBS modified material according to claim 1, characterized in that: The lubricant is one of fatty acid, fatty acid ester and fatty acid amide.

9. A method for preparing the low-temperature-resistant PVC / SEBS modified material according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1): Weigh by weight: PVC: 80-100 parts, SEBS: 20-40 parts, plasticizer: 5-20 parts, cold-resistant agent: 6-10 parts, flame retardant: 2-4 parts, antioxidant: 5-8 parts, stabilizer: 2-3 parts, lubricant: 3-5 parts; (2): Add all components into a high-speed mixer and mix them. Then, introduce the mixture into a twin-screw extruder for extrusion and granulation, air-cool and sieve to obtain the PVC / SEBS modified material.

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