Vinyl copolymer for improving compatibility of PVC and HDPE, preparation method thereof, and PVC composition

Abstract

The present invention relates to a vinyl copolymer for improving the compatibility of PVC and HDPE, characterized in that the vinyl copolymer has the general structural formula: CH3-(CH2) n ‑b‑(CHCl) m -CH3, wherein n ≥ 7 and the chlorine content ≥ 20 wt%; the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer are arranged in a block distribution. The present invention also relates to a method for preparing a vinyl copolymer for improving the compatibility of PVC and HDPE, and a PVC composition comprising the vinyl copolymer. The vinyl polymer of the present invention acts as a compatibilizer for PVC and HDPE, eliminating the need for other compatibilizers after use, and can improve the impact resistance of the PVC composition.

Description

Technical Field

[0001] The invention belongs to the field of polyolefin resins, and particularly relates to a vinyl copolymer for improving the compatibility of PVC and HDPE, a preparation method thereof, and a PVC composition containing the vinyl copolymer. Background Art

[0002] Polyvinyl chloride (PVC) is primarily used as a building material and plastic pipes. PVC plastic profiles are widely used in interior and exterior building windows and doors, as well as in the decorative industry. They offer excellent properties such as thermal insulation, sealing, energy conservation, sound insulation, and affordability. Since their introduction, the product has experienced rapid growth. PVC pipes offer advantages such as light weight, corrosion resistance, high strength, weather resistance, and flame retardancy. However, PVC also has inherent drawbacks, such as low-temperature brittleness, low impact strength, and poor crack resistance, which can lead to numerous problems and inconveniences during installation and use. Therefore, improvements to PVC's impact resistance are crucial.

[0003] At present, the commonly used impact modifiers for PVC include chlorinated polyethylene, polyacrylates, methyl methacrylate-butadiene-styrene terpolymer, acrylonitrile-butadiene-styrene copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene rubber, etc.

[0004] High-density polyethylene (HDPE) boasts excellent heat resistance, cold resistance, aging resistance, and chemical stability. It also possesses excellent mechanical strength, high rigidity and toughness, and is easy to process. It can be made into packaging films, water pipes, fishing nets, turnover boxes, and various hollow products. However, due to the poor compatibility of PVC and HDPE, the condensed structure and performance of their mechanical blends remain poorly improved, hindering the goal of enhancing the impact resistance of PVC. To improve the compatibility of PVC and HDPE, chlorinated polyethylene is often added as a compatibilizer.

[0005] Currently, chlorinated polyethylene (CPE) is primarily produced from powdered high-density polyethylene (HDPE) via aqueous suspension chlorination. Due to differences in molecular weight and molecular weight distribution, crystallization capacity, particle size distribution, specific surface area, and chlorination reaction conditions, the chlorine content and the sequence structure of Cl atoms distributed along the molecular chain of the HDPE vary, resulting in varying residual crystallinity (the degree of crystallinity of the unchlorinated polyethylene segments) in the resulting CPE. Experiments have shown that CPE with varying residual crystallinity exhibits distinct compatibilizing effects on mechanical blending of HDPE and PVC, directly affecting their compatibility and resulting in different cohesive structures, which in turn impacts the performance of the PVC / HDPE / CPE ternary blend.

[0006] CN201510224165.1 uses chlorinated polyethylene with a chlorine content of 15% to 20% and a melting enthalpy of 15 J / g to 25 J / g as a compatibilizer for high-density polyethylene blends with modified polyvinyl chloride. CN201710024884.8 uses highly branched polyethylene to improve the impact resistance of PVC, but still requires chlorinated polyethylene, methyl methacrylate-grafted EPDM rubber, and maleic anhydride-grafted EPDM rubber as compatibilizers. A simple and easily synthesized compatibilizer for HDPE / PVC blends remains lacking.

[0007] Functional modification of polyolefins has always been an important topic and challenge in academia and industry. Currently, most polyolefins are produced by coordination polymerization, which introduces active groups into the polyolefin. In the second step, active / controlled polymerization is used to introduce polar grafts or blocks with controllable characteristics (including chain length, molecular weight distribution, and structure) into the polyolefin to prepare polyolefin-based copolymers. Currently, the commonly used active / controlled polymerization methods can be divided into four categories: (1) anionic polymerization; (2) nitroxide-mediated free radical polymerization (NMRP); (3) atom transfer radical polymerization (ATRP); and (4) reversible addition-fragmentation chain transfer polymerization (RAFT). Hillmyer et al. (J. Polym. Sci., Part A: Polym. Chem. 2001, 39, 2755.) reported that linear polyethylene block polylactic acid copolymer (PE-b-PLLA) was prepared by combining coordination polymerization and anionic ring-opening polymerization. Chung et al. (Polymer 2005, 46, 10585.) and Kim et al. (Macromolecules, 2002, 35, 8923.) reported that linear polyethylene block polycaprolactone copolymer (PE-b-PCL) was prepared by combining coordination polymerization and anionic ring-opening polymerization. Kashiwa et al. (J. Polym. Sci., Part A: Polym. Chem. 2003, 41, 3965.) and Matyjaszewski et al. (Macromolecules 2005, 38, 5425.; J. Polym. Sci., Part A: Polym. Chem. 2004, 42, 496.) reported the preparation of linear polyethylene block polystyrene, polybutyl acrylate, polytert-butyl acrylate, polymethyl methacrylate copolymers (PE-b-PS, PE-b-PnBA, PE-b-PtBA, PE-b-PMMA) by combining coordination polymerization and ATRP. Zhu et al. (Macromol. Chem. P hys.2010,211,1452.) reported that linear polyethylene block poly(ethylene methacrylate oligomer) (PE-b-POEGMA) copolymers were prepared by combining coordination polymerization with ATRP, Kashiwa et al. (Polym.Bull.2006,57,805.) reported that linear polyethylene block poly(methyl methacrylate) copolymers (PE-b-PMMA) were prepared by combining coordination polymerization with RAFT, and Zhu et al. (Macromolecules 2009,42,3804.) reported that linear polyethylene block polyethylene oxide block copolymers (PE-b-PEO) were prepared by combining coordination polymerization with click reaction.

[0008] At present, the synthesis of polyolefin block and graft copolymers is mostly concentrated on the combination of coordination polymerization, anionic ring-opening polymerization and ATRP. Due to the limitations of the polymerization method, the polar segments of the synthesized block copolymers are mostly polycaprolactone, polyethylene oxide, polystyrene, poly(meth)acrylates, etc. There are few reports on the combination of other polar segments with special properties with polyolefins. Summary of the Invention

[0009] Based on the foregoing, the present invention aims to provide a vinyl copolymer capable of improving the compatibility of PVC and HDPE, and a method for preparing the same. This vinyl copolymer, as a compatibilizer for PVC and HDPE, eliminates the need for additional compatibilizers and improves the impact resistance of PVC compositions.

[0010] Another object of the present invention is to provide a PVC composition containing the above-mentioned vinyl copolymer.

[0011] To this end, the present invention provides a vinyl copolymer (polyethylene block polyvinyl chloride) for improving the compatibility of PVC and HDPE, the general structural formula of the vinyl copolymer is: CH3-(CH2) n -b-(CHCl) m -CH3, wherein n ≥ 7, the chlorine content ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0012] Specifically, the long alkyl chain -(CH2) of the vinyl copolymer of the present invention n - can be entangled with polyethylene molecular chains during the melt extrusion process, polyvinyl chloride chain - (CHCl) m - The polarity of the non-polar polyethylene resin is increased, which improves the compatibility of the polyethylene resin and PVC when blended with PVC. During the cooling crystallization process, an interconnected condensed network structure can be formed, which can improve the overall performance of the PVC composition.

[0013] The vinyl copolymer for improving the compatibility of PVC and HDPE of the present invention preferably has a chlorine content of 40 wt% to 60 wt%.

[0014] To this end, the present invention also provides a method for preparing an ethylene copolymer for improving the compatibility of PVC and HDPE, comprising the following steps:

[0015] S1, alkyl alcohol CH3-(CH2) n OH reacts with 4,4'-azobis(4-cyanovaleric acid) to obtain an initiator containing an azo group and a long alkyl chain CH3-(CH2)n -Azo-(CH2) n -CH3, wherein Azo is 4,4'-azobis(4-cyanovaleric acid) ester, and n≥7;

[0016] S2, the initiator initiates the polymerization of vinyl chloride to obtain a vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n ≥ 7, the chlorine content ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0017] To this end, the present invention also provides a method for preparing a vinyl copolymer for improving the compatibility of PVC and HDPE, comprising the following steps: using an organic halide CH3-(CH2) containing a long alkyl chain n -X as initiator, Cu 0 / The ligand acts as a catalyst to initiate the polymerization of vinyl chloride in water or a strong polar solvent to obtain vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n ≥ 7, X is a halogen, preferably Br or I, the chlorine content is ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0018] To this end, the present invention also provides a method for preparing a vinyl copolymer for improving the compatibility of PVC and HDPE, comprising the following steps: using an organic halide CH3-(CH2) containing a long alkyl chain to prepare a vinyl copolymer; n -X is used as an initiator to initiate the polymerization of vinyl chloride monomer in the NaHCO3 / Na2S2O4 system to prepare vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n ≥ 7, X is Br or I, the chlorine content is ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0019] In the method for preparing the vinyl copolymer of the present invention, it is preferred that the organic halide is a halogenated hydrocarbon, and the halogenated hydrocarbon includes at least one of 1-bromooctane, bromotetradecane, bromohexadecane, and bromooctadecane.

[0020] The method for preparing the vinyl copolymer of the present invention is preferably that the organic halide is generated by reacting the hydroxyl group of a long-chain fatty alcohol with a halogenating agent, and further preferably, the halogenating agent is 2-bromoisobutyryl bromide, and the long-chain fatty alcohol is CH3-(CH2) n OH, n≥7.

[0021] To this end, the present invention also provides a PVC composition, which comprises:

[0022] (A) PVC, 100 parts by mass;

[0023] (B) High-density polyethylene, density greater than 0.935 g / cm 3 , 2 to 30 parts by mass;

[0024] (C) 1 to 10 parts by mass of the vinyl copolymer according to claim 1.

[0025] The PVC composition of the present invention preferably further comprises:

[0026] (D) 1 to 15 parts by mass;

[0027] Among them, R1 is an alkyl group or a polyethylene group with a carbon chain length greater than 8 carbon atoms, R2 is COOR, R is an alkyl group, and R3 is H or CH3.

[0028] In the PVC composition of the present invention, it is preferred that R1 is n-octyl, n-decyl, n-dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, hexacosyl, octacosyl, triacontyl or dotriacontyl.

[0029] The PVC composition of the present invention is preferably wherein component (D) is initiated by a halogenated hydrocarbon or a chemically modified long-chain fatty alcohol monomer. The polymerization is obtained, wherein R2 is COOR, R is an alkyl group, and R3 is H or CH3. Preferably, the halogenated hydrocarbon includes at least one of 1-bromooctane, 1-chlorodecane, chlorotetradecane, bromotetradecane, bromohexadecane, and bromooctadecane, and the long-chain fatty alcohol is CH3-(CH2) n OH, n≥7.

[0030] Any compound known in the art containing a group capable of initiating polymerization of such monomers can be used in the present invention to chemically modify the hydroxyl groups of long-chain fatty alcohols to obtain the chemically modified long-chain fatty alcohols. For example, the hydroxyl groups of long-chain fatty alcohols can be modified with a halogenating agent (e.g., 2-bromoisobutyryl bromide) to directly initiate atom transfer radical polymerization or single electron transfer radical polymerization of the monomers. The hydroxyl groups of long-chain fatty alcohols can also be modified with thioester groups (e.g., 4-cyanopentanoic acid dithiobenzoate, propyl α-carboxydithiobenzoate, 4-cyanopentanoic acid dithiobenzoate, etc.) to initiate reversible addition-fragmentation transfer radical polymerization of the monomers.

[0031] The above polymerization reaction can adopt various existing polymerization techniques, such as atom transfer radical polymerization of monomers initiated by organic halide in transition metal halide / bipyridine system; or using Cu 0 / ligand as a catalyst, in water or a strongly polar solvent system, an organic halide is used to initiate the monomer to carry out single electron transfer radical polymerization at room temperature or lower temperature; or a RAFT agent containing a long fatty chain (such as 2-cyano-2-propyldodecyl trithiocarbonate) is used to initiate the monomer to carry out reversible addition-fragmentation transfer radical polymerization.

[0032] Organic halides can be directly prepared using halogenated hydrocarbons, such as 1-bromooctane, 1-chlorodecane, chlorotetradecane, bromotetradecane, bromohexadecane, bromooctadecane, etc., or they can be prepared by reacting the hydroxyl group of a long-chain fatty alcohol with a halogenating agent (such as 2-bromoisobutyryl bromide).

[0033] The beneficial effects of the present invention are as follows:

[0034] The vinyl polymer of the present invention is used as a compatibilizer for PVC and HDPE, and no other compatibilizer is needed after use, and the impact resistance of the PVC composition can be improved.

[0035] The PVC composition of the present invention has good mechanical properties and impact resistance, and also has excellent properties such as easy processing. DETAILED DESCRIPTION

[0036] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and processes. However, the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments where specific conditions are not specified are generally based on conventional conditions.

[0037] The PVC used in the examples is WS-1000, and the high-density polyethylene (HDPE) used is 5000S (melt flow rate (2.16 kg weight) 1.0 g / 10 min, density 0.951 g / cm 3 ).

[0038] The chlorine content (mass fraction) of polyethylene is determined according to Method B in the standard "GB / T 7139-2002 Plastics - Vinyl chloride homopolymers and copolymers - Determination of chlorine content".

[0039] The vinyl copolymer of the present invention can be prepared by one of the following methods:

[0040] Method 1:

[0041] First, the alkyl alcohol CH3-(CH2) n OH, 4,4'-azobis(4-cyanovaleric acid) and DMAP (4-dimethylaminopyridine) were added to the reactor and stirred to dissolve; DCC (N,N-dicyclohexyl diimide carbonate) solution was slowly added dropwise to the reactor. After the reaction was completed, it was filtered, purified and dried to obtain an initiator containing an azo group and a long alkyl chain, CH3-(CH2) n -Azo-(CH2) n -CH3, wherein Azo is 4,4'-azobis(4-cyanovaleric acid) ester, and n≥8;

[0042] Then, the initiator and 1,4-dioxane were added to the stainless steel sealed tube, and O2 was replaced with N2. Vinyl chloride was added to the sealed tube and polymerization was initiated at 60-80°C. The reaction was stopped after a period of time. The vinyl copolymer CH3-(CH2) was obtained by precipitation with ethanol, filtration, and vacuum drying. n -b-(CHCl) m -CH3, wherein n ≥ 7, the chlorine content ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0043] Method 2:

[0044] Use organic halides containing long alkyl chains CH3-(CH2) n -X as initiator, Cu 0 / ligand as a catalyst to initiate the polymerization of vinyl chloride in water or a strong polar solvent system to prepare vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n ≥ 7, the chlorine content ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0045] Among them, the organic halide can be directly halogenated hydrocarbons, such as 1-bromooctane, bromotetradecane, bromohexadecane, bromooctadecane, etc., or it can be generated by the reaction of the hydroxyl group of a long-chain fatty alcohol with a halogenating agent (such as 2-bromoisobutyryl bromide).

[0046] Method 3:

[0047] Add solvent, organic halide containing long alkyl chain CH3-(CH2) n -X, dispersant, NaHCO3 and Na2S2O4, fill with nitrogen to check air tightness, exhaust, evacuate, and fill with nitrogen to remove oxygen; add vinyl chloride monomer, stir and disperse at room temperature, then heat and react for 24 hours, then stop heating, cool to room temperature and stop stirring, let it stand, then discharge, filter and dry to obtain vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n ≥ 7, the chlorine content ≥ 20 wt%, the value of m is determined according to the chlorine content, and b is the abbreviation of block, which indicates that the arrangement of the alkyl chains -(CH2)n- and the polyvinyl chloride chains -(CHCl)m- in the copolymer is a block distribution.

[0048] Example 1

[0049] First, 50 mmol of dodecanol CH3-(CH2) 11 OH, 25 mmol 4,4'-azobis(4-cyanovaleric acid) and 0.5 g DMAP were added to a reactor containing 200 mL 0°C DMF and stirred to dissolve. 60 mmol DCC was dissolved in 100 mL DMF and slowly added dropwise to the reactor. The mixture was reacted at 0°C for 24 h. The mixture was filtered, the filtrate was precipitated with distilled water, filtered again, and the filter cake was freeze-dried to obtain an initiator containing an azo group and a long alkyl chain (CH3-(CH2) 11 -Azo-(CH2) 11 -CH3). Then, 1.0 g of initiator (CH3-(CH2) 11 -Azo-(CH2) 11 -CH3), 100ml 1,4-dioxane was added to a 500ml stainless steel sealed tube, and O2 was replaced with N2. 30g vinyl chloride was added to the sealed tube and polymerization was initiated at 68°C. The reaction was stopped after 12 hours. The vinyl copolymer CH3-(CH2) was precipitated with ethanol, filtered, and dried in vacuum to obtain 11 -b-(CHCl) m -CH3, wherein the chlorine content is 45 wt%.

[0050] Example 2

[0051] First, 30 mmol of triacontanol CH3-(CH2)29 OH, 15 mmol 4,4'-azobis(4-cyanovaleric acid) and 0.3 g DMAP were added to a reactor containing 100 mL of 0°C dichloromethane and stirred to dissolve. 40 mmol DCC was dissolved in 70 mL of dichloromethane and slowly added dropwise to the reactor. The mixture was reacted at 0°C for 20 h. Filtered, the filtrate was precipitated with distilled water, filtered again, and the filter cake was freeze-dried to obtain an initiator containing an azo group and a long alkyl chain (CH3-(CH2) 29 -Azo-(CH2) 29 -CH3).

[0052] Next, 2.0 g of initiator (CH3-(CH2) 29 -Azo-(CH2) 29 -CH3), 100ml 1,4-dioxane was added to a 500ml stainless steel sealed tube, and O2 was replaced with N2. 50g vinyl chloride was added to the sealed tube and polymerization was initiated at 72°C. The reaction was stopped after 12 hours. The vinyl copolymer CH3-(CH2) was precipitated with ethanol, filtered, and dried in vacuum to obtain 29 -b-(CHCl) m -CH3, wherein the chlorine content is 39 wt%.

[0053] Example 3

[0054] Use of organic halides containing long alkyl chains C8H 17 Br as initiator, Cu 0 / TREN was used as a catalyst to initiate the polymerization of vinyl chloride in DMSO solvent to prepare vinyl copolymers.

[0055] Reaction conditions: DMSO as solvent, C8H 17 The polymerization was carried out in the Br / Cu0 / TREN system, the reaction temperature was 25°C, and the vinyl chloride / C8H 17 Br / copper powder / TREN=350 / 1 / 1 / 3 (molar ratio). The long alkyl chain in the ethylene copolymer contains 8 carbon atoms, and the chlorine content in the ethylene copolymer is 67 wt%.

[0056] Example 4

[0057] Add 5 mL of 1-tetradecanol to 100 mL of purified anhydrous dichloromethane. Add 10 mL of 2-bromoisobutyryl bromide dropwise in an ice-water bath. After reacting at room temperature for 24 hours, filter to remove insoluble matter. Evaporate the filtrate to dryness, dissolve the residue in dichloromethane, wash sequentially with saturated sodium bicarbonate solution and saturated brine, and dry over anhydrous sodium sulfate. Purify the crude product on a silica gel column using petroleum ether / ethyl acetate (3 / 1, v / v) to obtain a colorless oil, tetradecanol 2-bromoisobutyrate.

[0058] Reaction conditions: ethanol / THF (tetrahydrofuran) = 2 / 1 (V / V) as solvent, using Cu 0 / TREN system for polymerization, the reaction temperature is 30°C, vinyl chloride / tetradecyl 2-bromoisobutyrate / copper powder / TREN=500 / 1 / 2 / 4 (molar ratio).

[0059] The obtained vinyl copolymer CH3-(CH2) 13 -b-(CHCl) m -CH3, wherein the chlorine content is 56 wt%.

[0060] Example 5

[0061] Deionized water, octadecane bromide, polyvinyl alcohol, cellulose ether, NaHCO₃, and Na₂S₂O₄ were added to a stainless steel reactor. The reactor was then filled with nitrogen to check for tightness, vented, vacuumized, and filled with nitrogen five times to remove oxygen. Vinyl chloride monomer was then added in a molar ratio of octadecane bromide: NaHCO₃: Na₂S₂O₄: vinyl chloride of 1:20:4:50. The reactor was stirred and dispersed at room temperature for 20 minutes, then heated to 35°C and reacted at 400 rpm for 24 hours. Heating was stopped, the reactor cooled to room temperature, stirring was stopped, and the reactor allowed to stand for 24 hours. The resulting vinyl copolymer, octadecyl polyvinyl chloride, was filtered and dried. The long alkyl chain in the vinyl copolymer contained 18 carbon atoms, and the chlorine content was 52 wt%.

[0062] Example 6

[0063] Deionized water, hexadecane bromide, polyvinyl alcohol, cellulose ether, NaHCO₃, and Na₂S₂O₄ were added to a stainless steel reactor. The reactor was then filled with nitrogen to check for tightness, vented, vacuumized, and filled with nitrogen five times to remove oxygen. Vinyl chloride monomer (molar ratio of hexadecane bromide: NaHCO₃: Na₂S₂O₄: vinyl chloride: 1:20:4:80) was added. The mixture was stirred and dispersed at room temperature for 20 minutes, then heated to 35°C and reacted at 400 rpm for 24 hours. Heating was stopped, the mixture was cooled to room temperature, stirring was stopped, and the mixture was allowed to stand for 24 hours before being discharged, filtered, and dried to obtain a vinyl copolymer, hexadecyl polyvinyl chloride. The long alkyl chain in the vinyl copolymer contained 16 carbon atoms, and the chlorine content in the vinyl copolymer was 60 wt%.

[0064] Example 7

[0065] The PVC composition containing the vinyl copolymer provided in this embodiment comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC, 3 parts by mass of high-density polyethylene, and 2 parts by mass of the vinyl copolymer prepared in Example 1.

[0066] Example 8

[0067] The PVC composition containing the vinyl copolymer provided in this embodiment comprises, based on 100 parts by mass of PVC, 10 parts by mass of high-density polyethylene, and 6 parts by mass of the vinyl copolymer prepared in Example 2.

[0068] Example 9

[0069] The PVC composition containing the vinyl copolymer provided in this embodiment comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC, 25 parts by mass of high-density polyethylene, and 9 parts by mass of the vinyl copolymer prepared in Example 3.

[0070] Example 10

[0071] The PVC composition containing a vinyl copolymer provided in this embodiment comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC, 8 parts by mass of high-density polyethylene, 1 part by mass of the vinyl copolymer prepared in Example 4, and 3 parts by mass of triacontyl polymethyl methacrylate.

[0072] Triacontanyl polymethyl methacrylate was prepared as follows: First, α-carboxydithiobenzoic acid propyl ester was prepared according to a published synthesis method (Journal of Chemistry in Higher Education Institutions, Vol. 29, No. 2, 2008, p. 404). 5 g of α-carboxydithiobenzoic acid propyl ester was added to a flask, followed by 25 mL of purified dichloromethane. After stirring to dissolve the resulting clear solution, 10 mL of purified thionyl chloride was syringed and added to the flask under stirring. The solution was then heated to 60°C, refluxed for 2 hours, cooled, and allowed to stand overnight. Excess thionyl chloride was removed under reduced pressure, and the mixture was allowed to stand overnight.

[0073] Add 2 mmol of triacontanol and 80 mL of purified dichloromethane to a flask. Stir to dissolve, then add 1 mL of dry, anhydrous pyridine. Dissolve the chlorinated α-carboxydithiobenzoic acid propyl ester in 20 mL of purified dichloromethane and add the resulting solution dropwise to the flask. Allow to react for 12 hours at room temperature in the dark. Add anhydrous sodium carbonate and let stand for 2 hours to remove the generated HCl. Filter the solution. Concentrate the filtrate, precipitate with icy methanol, filter, and wash with methanol. Finally, dry the filtered product, α-triacontyl ester propyl dithiobenzoate, in a vacuum oven at room temperature for 12 hours before use.

[0074] To a polymerization tube, add 6 mg of α-triacontyl propyl dithiobenzoate, 1 mg of azobisisobutyronitrile, 50 ml of methyl methacrylate, and 10 ml of acetone. Mix thoroughly, then repeat three cycles of cooling with liquid nitrogen, evacuating, purging with nitrogen, and thawing. Seal the tube under vacuum and stir at 80°C for 10 hours. The crude product is precipitated in methanol / water (v / v: 1 / 1) and dried to obtain triacontyl polymethyl methacrylate.

[0075] Example 11

[0076] The PVC composition containing vinyl copolymer provided in this embodiment comprises, based on 100 parts by mass of PVC, 16 parts by mass of high-density polyethylene, 4 parts by mass of the vinyl copolymer prepared in Example 5, and 2 parts by mass of dodecyl polybutyl acrylate.

[0077] Dodecyl polybutyl acrylate was prepared as follows: 3 mg of 2-cyano-2-propyldodecyl trithiocarbonate, 1.6 mg of dibenzoyl peroxide, 34 ml of butyl acrylate, and 6 ml of acetone were added sequentially to a polymerization tube. The mixture was thoroughly mixed and then cooled with liquid nitrogen, evacuated, purged, and thawed three times. The tube was sealed under vacuum and stirred at 70°C for 12 hours. The crude product was precipitated in methanol / water (v / v: 1 / 1) and dried to obtain dodecyl polybutyl acrylate.

[0078] Comparative Example 1

[0079] The PVC composition provided in this comparative example comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC and 3 parts by mass of high-density polyethylene.

[0080] Comparative Example 2

[0081] The PVC composition provided in this comparative example comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC and 10 parts by mass of high-density polyethylene.

[0082] Comparative Example 3

[0083] The PVC composition provided in this comparative example comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC and 25 parts by mass of high-density polyethylene.

[0084] Comparative Example 4

[0085] The PVC composition provided in this comparative example comprises, based on 100 parts by mass of PVC, 10 parts by mass of high-density polyethylene, and 6 parts by mass of chlorinated polyethylene (chlorine content (mass fraction) is 35%) as a compatibilizer.

[0086] Comparative Example 5

[0087] The PVC composition containing vinyl copolymer provided in this comparative example comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC, 8 parts by mass of high-density polyethylene, and 3 parts by mass of triacontyl polymethyl methacrylate.

[0088] Comparative Example 6

[0089] The PVC composition containing vinyl copolymer provided in this comparative example comprises, based on 100 parts by mass of PVC, 100 parts by mass of PVC, 16 parts by mass of high-density polyethylene, and 2 parts by mass of dodecyl polybutyl acrylate.

[0090] The performance comparison of the PVC compositions in Examples 7-11 and Comparative Examples 1-6 is shown in Table 1.

[0091] Table 1 Comparison of properties of PVC compositions in Examples and Comparative Examples

[0092]

[0093] As can be seen from Table 1, without the addition of the vinyl copolymer of the present invention (Comparative Examples 1 to 3), the impact properties of the high-density polyethylene / PVC composition do not change significantly compared to the PVC used, and there is a decrease in tensile strength, an increase in maximum torque or a prolongation of equilibrium time, which affects its overall performance and processing performance. The addition of the vinyl copolymer of the present invention improves the compatibility of the high-density polyethylene / PVC composition, can significantly improve the impact properties of the composition, and the tensile strength remains stable or increases. The equilibrium torque decreases or the equilibrium time is shortened, and the composition has better processing performance. When using the vinyl copolymer containing After the polymer (D) containing the structural unit is added, it plays a synergistic role with the vinyl copolymer and can significantly improve the impact resistance and processing performance of the composition when the addition amount is relatively low (Examples 10-11). The polymer (D) containing the structural unit cannot significantly improve the impact performance of the composition (Comparative Examples 5-6).

[0094] By comparing Example 8 with Comparative Example 4, it can be seen that the vinyl polymer provided by the present invention has the advantage of better improving the compatibility of PVC and HDPE compared to the existing PVC and HDPE compatibilizer chlorinated polyethylene, which is manifested in that at the same addition amount, the composition of Example 8 has higher impact strength and tensile strength than the composition of Comparative Example 4, and a shorter equilibrium time.

[0095] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the present invention.

Claims

1. A vinyl copolymer for improving the compatibility of PVC and HDPE, characterized in that: The general structural formula of the vinyl copolymer is: CH3-(CH2) n -b-(CHCl) m -CH3, wherein n≥7, and the chlorine content is ≥20wt%; the alkyl chain -(CH2)n- and the polyvinyl chloride chain -(CHCl)m- are arranged in a block distribution in the copolymer.

2. The vinyl copolymer for improving the compatibility of PVC and HDPE according to claim 1, characterized in that The chlorine content in the vinyl copolymer is 40 wt% to 60 wt%.

3. A method for preparing a vinyl copolymer for improving the compatibility of PVC and HDPE, characterized in that: The following steps are involved: S1, alkyl alcohol CH3-(CH2) n OH reacts with 4,4'-azobis(4-cyanovaleric acid) to obtain an initiator containing an azo group and a long alkyl chain CH3-(CH2) n -Azo-(CH2) n -CH3, wherein Azo is 4,4'-azobis(4-cyanovaleric acid) ester, and n≥7; S2, the initiator initiates the polymerization of vinyl chloride to obtain a vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n≥7 and chlorine content≥20wt%.

4. A method for preparing a vinyl copolymer for improving the compatibility of PVC and HDPE, characterized in that: The process comprises the following steps: using an organic halide CH3-(CH2) containing a long alkyl chain n -X as initiator, Cu 0 / The ligand acts as a catalyst to initiate the polymerization of vinyl chloride in water or a strong polar solvent to obtain vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n≥7, and X is a halogen.

5. A method for preparing a vinyl copolymer for improving the compatibility of PVC and HDPE, characterized in that: The process comprises the following steps: using an organic halide CH3-(CH2) containing a long alkyl chain n -X is used as an initiator to initiate the polymerization of vinyl chloride monomer in the NaHCO3 / Na2S2O4 system to prepare vinyl copolymer CH3-(CH2) n -b-(CHCl) m -CH3, wherein n≥7, X is Br or I, and the chlorine content is ≥20wt%.

6. The method for preparing the vinyl copolymer according to claim 4 or 5, characterized in that: The organic halide is a halogenated hydrocarbon, and the halogenated hydrocarbon includes at least one of 1-bromooctane, bromotetradecane, bromohexadecane, and bromooctadecane.

7. The method for preparing the vinyl copolymer according to claim 4 or 5, characterized in that: The organic halide is generated by the reaction of the hydroxyl group of the long-chain fatty alcohol with a halogenating agent.

8. A PVC composition, characterized in that The composition comprises: (A) PVC, 100 parts by mass; (B) High-density polyethylene, density greater than 0.935 g / cm 3 , 2 to 30 parts by mass; (C) 1 to 10 parts by mass of the vinyl copolymer according to claim 1.

9. The PVC composition according to claim 8, characterized in that The composition also includes: (D) 1 to 15 parts by mass; Among them, R1 is an alkyl group or a polyethylene group with a carbon chain length greater than 8 carbon atoms, R2 is COOR, R is an alkyl group, and R3 is H or CH3.

10. The PVC composition according to claim 9, characterized in that The R1 is n-octyl, n-decyl, n-dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, hexacosyl, octacosyl, triacontyl or dotriacontyl.

11. The PVC composition according to claim 9, characterized in that Component (D) is a monomer initiated by a halogenated hydrocarbon or a chemically modified long-chain fatty alcohol. The obtained product is obtained by polymerization, wherein R2 is COOR, R is an alkyl group, and R3 is H or CH3.

12. The method for preparing the vinyl copolymer according to claim 4, wherein: X is Br or I, and the chlorine content is ≥ 20 wt%.

13. The method for preparing a vinyl copolymer according to claim 7, wherein: The halogenating agent is 2-bromoisobutyryl bromide, and the long-chain fatty alcohol is CH3-(CH2) n OH, n≥7.

14. The PVC composition according to claim 11, characterized in that The halogenated hydrocarbon includes at least one of 1-bromooctane, 1-chlorodecane, chlorotetradecane, bromotetradecane, bromohexadecane, and bromooctadecane, and the long-chain fatty alcohol is CH3-(CH2) n OH, n≥7.

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