Propylene-based olefin block copolymer with flame retardant function, preparation method thereof and composition containing recycled plastic

Abstract

The invention discloses a propylene-based olefin block copolymer with a flame retardant function, a preparation method thereof, and a composition containing recycled plastics. The propylene-based olefin block copolymer with a flame retardant function contains: a first block and a second block; the first block contains a polypropylene block, and the second block contains a copolymer block of propylene, ethylene, and a monomer containing a phosphonic acid group and a carbon-carbon double bond. The composition containing recycled plastics includes: polyethylene recycled plastics, polypropylene recycled plastics, and the propylene-based olefin block copolymer with a flame retardant function. The propylene-based olefin block copolymer with a flame retardant function of the invention can be used as a compatibilizer in ethylene-propylene recycled plastics, so that the ethylene-propylene recycled plastics have excellent mechanical properties and flame retardant properties.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant materials, in particular to a propylene-based olefin block copolymer with flame retardant function, a preparation method thereof and a composition containing recycled plastics. Background Art

[0002] Polyethylene and polypropylene plastics are the most widely used synthetic plastics in today's society due to their simple structure, excellent performance and low cost. Together, they account for nearly 60% of global plastic production. However, both plastics are high-molecular materials that are difficult to degrade and will cause continuous environmental pollution after being discarded. Therefore, the effective recycling and high-value reuse of polyethylene and polypropylene have received widespread attention in recent years.

[0003] It is worth pointing out that polyethylene and polypropylene are often mixed in the same scenario, such as polyethylene for the bottle body and polypropylene for the bottle cap. It is difficult to achieve thorough sorting during recycling, but the two are thermodynamically incompatible. Recycling and blending will cause serious phase separation, making the mechanical properties of the recycled plastic very poor, making it difficult to reuse at a high value.

[0004] The prior art uses olefin block copolymers as compatibilizers in the recycling of EPDM plastics, which reduces the interfacial tension between the two and increases the compatibility between the two, thereby increasing the mechanical properties of the recycled plastics, such as impact strength. However, since polyethylene, polypropylene and olefin block copolymers are composed of only carbon and hydrogen, they have a very low oxygen index and are very easy to burn. They also release a lot of heat during combustion, and droplets are generated during the process, which accelerates the spread of flames and even causes explosions. This will seriously limit the application prospects of olefin block copolymers as compatibilizers in the recycling of EPDM plastics.

[0005] Usually in the preparation of polyethylene and polypropylene flame retardant materials, it is realized by adding flame retardant, and flame retardant is generally divided into reactive type and additive type, and additive flame retardant is the most commonly used. Phosphorus flame retardant is a very important one in additive flame retardant, but it can be seen from the report of CN104693604A that the introduction of phosphorus flame retardant particles in the matrix can destroy the interface bonding, and the mechanical properties are significantly reduced. Therefore, as reported in CN109679203A and CN117866336A, when using this additive flame retardant, reinforcement is usually added to improve the mechanical properties of flame retardant materials. In addition, if red phosphorus is directly used as flame retardant, although the flame retardant efficiency is very high, red phosphorus is easy to absorb moisture, and coating technology is usually used to prevent red phosphorus from failing. And the use of coating technology makes the production cost higher and the process is more complicated.

[0006] Therefore, developing a compatibilizer for EPDM recycled plastics so that the recycled plastics have both excellent mechanical properties and flame retardant properties has become one of the urgent problems to be solved in this field. Summary of the invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a propylene-based olefin block copolymer with flame retardant function and a preparation method thereof and a composition containing recycled plastics. The propylene-based olefin block copolymer with flame retardant function of the present invention can be used as a compatibilizer in ethylene-propylene recycled plastics, so that the ethylene-propylene recycled plastics have excellent mechanical properties and flame retardant properties.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a propylene-based olefin block copolymer with flame retardant function, which contains: a first block and a second block; the first block contains a polypropylene block, and the second block contains a copolymer block of propylene, ethylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 20-30%, and the content of the second block is 70-80%.

[0009] According to a specific embodiment of the present invention, preferably, the ratio of the number average molecular weights of the first block and the second block is 1:(3-4).

[0010] According to a specific embodiment of the present invention, preferably, the first block contains an isotactic polypropylene block, and the isotacticity of the isotactic polypropylene block is 85-95%.

[0011] According to a specific embodiment of the present invention, preferably, the number average molecular weight of the first block is 15-30 kDa.

[0012] According to a specific embodiment of the present invention, preferably, in the second block, the molar ratio of the structural units derived from propylene, the structural units derived from ethylene and the structural units derived from the monomer containing a phosphonic acid group and a carbon-carbon double bond is (4-5): (1-2): (0.6-3.5).

[0013] According to a specific embodiment of the present invention, preferably, the monomer containing a phosphonic acid group and a carbon-carbon double bond includes one or more of vinylphosphonic acid, methyl vinylphosphonate, dimethyl vinylphosphonate, ethyl vinylphosphonate and diethyl vinylphosphonate.

[0014] According to a specific embodiment of the present invention, preferably, the number average molecular weight of the second block is 60-90 kDa.

[0015] According to a specific embodiment of the present invention, preferably, the number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 75-120 kDa, and the molecular weight distribution is 1.9-3.0.

[0016] According to a specific embodiment of the present invention, preferably, the limiting oxygen index of the flame-retardant propylene-based olefin block copolymer is 30-40%, and the flame retardant grade of the flame-retardant propylene-based olefin block copolymer is V-0 of UL94.

[0017] The second aspect of the present invention provides a method for preparing the above-mentioned propylene-based olefin block copolymer with flame retardant function, which comprises the following steps:

[0018] (1) Under anhydrous and oxygen-free condition, subjecting propylene to a first polymerization reaction in an organic solvent in the presence of a main catalyst, a co-catalyst and a chain transfer agent to obtain a mixed system after the first polymerization reaction;

[0019] (2) adding ethylene, propylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond to the mixed system after the first polymerization reaction under anhydrous and oxygen-free conditions to carry out a second polymerization reaction to obtain a mixed system after the second polymerization reaction;

[0020] (3) subjecting the mixed system after the second polymerization reaction to at least precipitation and solid-liquid separation to obtain the propylene-based olefin block copolymer having a flame retardant function;

[0021] The main catalyst comprises a complex of a ligand containing pyridine and imine and a transition metal of Group IVB, the co-catalyst comprises an organic boron compound, and the chain transfer agent comprises an alkyl aluminum compound and / or an alkyl zinc compound.

[0022] According to a specific embodiment of the present invention, preferably, the temperature of the first polymerization reaction is 25-70° C. and the pressure is 0.1-0.5 MPa.

[0023] According to a specific embodiment of the present invention, preferably, the main catalyst comprises a complex having a structure as shown in Formula I and / or Formula II:

[0024] Formula I

[0025] Formula II

[0026] wherein M is selected from one of the Group IVB transition metals;

[0027] R1 and R2 are each independently selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group and a substituted or unsubstituted polycyclic aromatic group.

[0028] According to a specific embodiment of the present invention, preferably, the co-catalyst includes one or more of trityltetrakis(pentafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate and tetra-n-butylammoniumtetraphenylborate.

[0029] According to a specific embodiment of the present invention, preferably, the chain transfer agent includes one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylzinc, methylaluminoxane, modified methylaluminoxane, ethylaluminoxane and isobutylaluminoxane.

[0030] According to a specific embodiment of the present invention, preferably, the molar ratio of the main catalyst to the chain transfer agent is 1:(150-200).

[0031] According to a specific embodiment of the present invention, preferably, the temperature of the second polymerization reaction is 25-70° C. and the pressure is 0.1-0.5 MPa.

[0032] The third aspect of the present invention provides a composition comprising recycled plastics, comprising: polyethylene recycled plastics, polypropylene recycled plastics and a compatibilizer, wherein the compatibilizer comprises the above-mentioned propylene-based olefin block copolymer with flame retardant function; wherein the mass ratio of the total amount of the polyethylene recycled plastics and the polypropylene recycled plastics to the compatibilizer is 8:(1~2).

[0033] The present invention has at least the following beneficial effects:

[0034] The propylene-based olefin block copolymer with flame retardant function of the present invention contains a first block and a second block; the first block contains a polypropylene block, which is a hard segment; the second block contains a copolymer block of propylene, ethylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond, which is a soft segment. The propylene-based olefin block copolymer contains both a polypropylene segment and a copolymer segment containing an ethylene structural unit. The propylene-based olefin block copolymer is used as a compatibilizer in ethylene-propylene recycled plastics. The polyethylene and polypropylene in the recycled plastics are combined with similar segments in the propylene-based olefin block copolymer, which increases the compatibility of polyethylene and polypropylene, so that the recycled plastics have excellent mechanical properties. At the same time, compared to the random copolymer or graft copolymer formed by propylene, ethylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond, the advantage of the block copolymer of the present invention as a compatibilizer is that its structure is highly adjustable, and the compatibility can be improved by adjusting the content or ratio of the soft segment and the hard segment according to the ratio of the polyethylene and polypropylene in the recycled plastics, which significantly increases the universality of the block copolymer of the present invention as a compatibilizer. Moreover, since the second block of the propylene olefin block copolymer contains a structural unit from a monomer containing a phosphonic acid group and a carbon-carbon double bond, the propylene olefin block copolymer has a flame retardant function, and is used as a compatibilizer in ethylene-propylene recycled plastics, so that the recycled plastics have excellent flame retardant properties, and its application scenarios are broadened. In addition, the present invention does not adopt the prior art method of introducing a material with a flame retardant function into the recycled plastic by blending, but introduces a monomer containing a phosphonic acid group and a carbon-carbon double bond by copolymerization, and obtains a propylene olefin block copolymer as a compatibilizer, avoiding the adverse effects of the flame retardant material introduced by blending on the mechanical properties of the recycled plastic, so that the recycled plastic has both excellent flame retardant properties and mechanical properties, and does not increase the complexity of the preparation process of the recycled plastic with flame retardant properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a scanning electron microscope image of the recycled plastic of Example 1.

[0036] Figure 2 This is a scanning electron microscope image of the recycled plastic of Example 2.

[0037] Figure 3 This is a scanning electron microscope image of the recycled plastic of Example 3.

[0038] Figure 4 This is a scanning electron microscope image of the recycled plastic of Example 4.

[0039] Figure 5 This is a scanning electron microscope image of the recycled plastic of Example 6.

[0040] Figure 6 This is a scanning electron microscope image of the recycled plastic of Comparative Example 1.

[0041] Figure 7 This is a scanning electron microscope image of the recycled plastic of Comparative Example 2. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the present invention is now described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0043] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0044] It should be noted that, unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0045] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0046] According to a specific embodiment of the first aspect of the present invention, the present invention provides a propylene-based olefin block copolymer with a flame retardant function, which contains: a first block and a second block; the first block contains a polypropylene block, and the second block contains a copolymer block of propylene, ethylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond; based on the total number average molecular weight of the propylene-based olefin block copolymer with a flame retardant function as 100%, the content of the first block is 20-30%, for example, 20%, 25% or 30%, and the content of the second block is 70-80%, for example, 70%, 75% or 80%, and the like.

[0047] In some embodiments, the ratio of the number average molecular weights of the first block and the second block is 1:(3-4).

[0048] In some embodiments, the first block contains an isotactic polypropylene block, and the isotacticity of the isotactic polypropylene block is 85-95%, such as 85%, 86%, 88%, 90%, 92%, 94% or 95%, etc., preferably 90-95%.

[0049] In some embodiments, the number average molecular weight of the first block is 15-30 kDa, preferably 20-25 kDa; the molecular weight distribution of the first block is 1.9-2.1.

[0050] In some embodiments, the molar ratio of the structural units derived from propylene, the structural units derived from ethylene, and the structural units derived from the monomer containing a phosphonic acid group and a carbon-carbon double bond in the second block is (4-5): (1-2): (0.6-3.5), preferably 5:1: (1-2).

[0051] In some embodiments, the monomer containing a phosphonic acid group and a carbon-carbon double bond includes one or more of vinylphosphonic acid, methyl vinylphosphonate, dimethyl vinylphosphonate, ethyl vinylphosphonate, diethyl vinylphosphonate, and the like.

[0052] In some embodiments, the number average molecular weight of the second block is 60-90 kDa, preferably 70-85 kDa; the molecular weight distribution of the second block is 1.9-3.0.

[0053] In some embodiments, the number average molecular weight of the flame retardant propylene-based olefin block copolymer is 75-120 kDa, preferably 90-110 kDa; the molecular weight distribution of the flame retardant propylene-based olefin block copolymer is 1.9-3.0.

[0054] In some embodiments, the limiting oxygen index of the flame-retardant propylene-based olefin block copolymer is 30-40%, and the flame retardant grade of the flame-retardant propylene-based olefin block copolymer is V-0 of UL94.

[0055] According to a specific embodiment of the second aspect of the present invention, the present invention provides a method for preparing the above-mentioned propylene-based olefin block copolymer with flame retardant function, which comprises the following steps:

[0056] (1) Under anhydrous and oxygen-free conditions, subjecting propylene to a first polymerization reaction in an organic solvent in the presence of a main catalyst, a co-catalyst and a chain transfer agent to obtain a mixed system after the first polymerization reaction;

[0057] (2) adding ethylene, propylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond to the mixed system after the first polymerization reaction under anhydrous and oxygen-free conditions to carry out a second polymerization reaction to obtain a mixed system after the second polymerization reaction;

[0058] (3) subjecting the mixed system after the second polymerization reaction to at least precipitation and solid-liquid separation to obtain the propylene-based olefin block copolymer having a flame retardant function;

[0059] The main catalyst comprises a complex of a ligand containing pyridine and imine and a transition metal of Group IVB, the co-catalyst comprises an organic boron compound, and the chain transfer agent comprises an alkyl aluminum compound and / or an alkyl zinc compound.

[0060] In some embodiments, the temperature of the first polymerization reaction is 25-70° C. and the pressure is 0.1-0.5 MPa.

[0061] In some embodiments, the main catalyst includes a complex having a structure as shown in Formula I and / or Formula II:

[0062] Formula I

[0063] Formula II

[0064] Wherein, M is selected from one of the transition metals of Group IVB, specifically, M is selected from one of titanium (Ti), zirconium (Zr) and hafnium (Hf);

[0065] Me stands for methyl;

[0066] R1 and R2 are each independently selected from one of substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl and substituted or unsubstituted polycyclic aromatic groups. Specifically, R1 and R2 are each independently selected from one of C1-C10 substituted or unsubstituted alkyl, C3-C10 substituted or unsubstituted cycloalkyl, C6-C20 substituted or unsubstituted aryl and C10 or more substituted or unsubstituted polycyclic aromatic groups. Among them, polycyclic aromatic groups include non-condensed polycyclic aromatic groups (such as biphenyl and biphenyl), and condensed aromatic groups (such as naphthyl, anthracenyl, phenanthrenyl, indenyl, fluorenyl, acenaphthenyl, pyrenyl and coronenyl). Preferably, R1 and R2 are each independently selected from one of phenyl and isopropyl substituted phenyl (such as 2,6-diisopropylphenyl).

[0067] The main catalyst used in the present invention can be prepared by a preparation method disclosed in the prior art, such as the preparation method disclosed in 2.2.4 of the paper reported by Yin Xiao (Yin Xiao. Preparation of stereoblock polypropylene by chain shuttling polymerization [D]. Tianjin University, 2020.).

[0068] In some embodiments, the co-catalyst includes one or more of trityltetrakis(pentafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, and tetra-n-butylammoniumtetraphenylborate.

[0069] In some embodiments, the chain transfer agent includes one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylzinc, methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, and the like.

[0070] In some embodiments, the molar ratio of the main catalyst to the chain transfer agent is 1:(150-200), for example, 1:150, 1:160, 1:170, 1:180, 1:190 or 1:200, etc.

[0071] In some embodiments, the molar ratio of the main catalyst to the co-catalyst is 1:(1-5). Generally speaking, the amount of the co-catalyst can be slightly higher than that of the main catalyst, and the molar ratio of the main catalyst to the co-catalyst is, for example, 1:(1.5-2).

[0072] In some embodiments, the organic solvent is a conventional inert organic solvent in the art, such as one or more of n-pentane, isopentane, n-hexane, cyclohexane, n-heptane, isoheptane, n-octane, isooctane, n-decane, toluene and xylene, etc. The amount of the organic solvent can be conventionally adjusted by those skilled in the art.

[0073] In some embodiments, the temperature of the second polymerization reaction is 25-70° C. and the pressure is 0.1-0.5 MPa.

[0074] In some embodiments, in step (1) and step (2), propylene and ethylene are introduced into the reaction system in the form of gas, and the monomer containing a phosphonic acid group and a carbon-carbon double bond is added to the reaction system by dropwise addition. The present invention does not impose any particular limitation on the molar ratio of the propylene and ethylene introduced in step (2) and the monomer containing a phosphonic acid group and a carbon-carbon double bond added dropwise, and can be adjusted by a person skilled in the art based on the molar ratio of the structural units from the three monomers in the second block described above.

[0075] In some embodiments, in step (3), the block copolymer may be precipitated using a conventional solvent in the art, such as an alcohol compound, etc. The solid-liquid separation may be performed by conventional filtering, etc. Furthermore, washing and drying may be performed to obtain the propylene-based olefin block copolymer having a flame retardant function.

[0076] According to a specific embodiment of the third aspect of the present invention, the present invention provides a composition comprising recycled plastics, comprising: polyethylene recycled plastics, polypropylene recycled plastics and a compatibilizer, wherein the compatibilizer comprises the above-mentioned propylene-based olefin block copolymer with flame retardant function; wherein the mass ratio of the total amount of the polyethylene recycled plastics and the polypropylene recycled plastics to the compatibilizer is 8:(1-2). wherein the mass ratio of the polyethylene recycled plastics to the polypropylene recycled plastics can be adjusted according to actual needs, for example, it can be 1:1, etc.

[0077] The propylene-based olefin block copolymer with flame retardant function of the present invention contains a first block and a second block; the first block contains a polypropylene block (preferably an isotactic polypropylene block), which is a hard segment; the second block contains a copolymer block of propylene, ethylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond, and the copolymer block is a random copolymer block, which is a soft segment. The present invention controls the content and ratio of the first block and the second block, as well as the ratio of the structural units from propylene, the structural units from ethylene and the structural units from the monomer containing a phosphonic acid group and a carbon-carbon double bond in the second block, so that when the block copolymer of the present invention is used as a compatibilizer in ethylene-propylene recycled plastics, it can not only make the recycled plastics have excellent mechanical properties, but also have a significant flame retardant effect, avoiding the high flammability of polyethylene and polypropylene recycled plastics in the prior art after blending. In addition, the preparation process of the block copolymer of the present invention is simple and easy to implement, and the purity of the propylene-based olefin block copolymer with flame retardant function of the present invention is high. Moreover, the composition containing recycled plastics of the present invention can reduce or even avoid adding other flame retardant materials during blending due to the use of the block copolymer, avoiding the problems of uneven blending and reduced mechanical properties caused by the introduction of flame retardant materials in a blending manner, and does not increase the complexity of the preparation process of recycled plastics with flame retardant properties. Therefore, the ethylene-propylene recycled plastic containing the block copolymer of the present invention has excellent mechanical properties and flame retardant properties at the same time, breaking through its long-term severely limited application scenarios.

[0078] The technical solutions of the present invention are specifically described below by way of examples, but the present invention is not limited to these examples and can of course be implemented in various modifications within the scope of the gist of the present invention.

[0079] Test method:

[0080] (1) Purity of the flame retardant propylene-based olefin block copolymer:

[0081] The test was performed using a cross-fractionation chromatograph (CFC), which combines temperature rising elution fractionation (TREF) and gel permeation chromatography (GPC). A sample (10 mg) of the polymer (i.e., the product in the following example) was placed in a disposable sample bottle and automatically injected into 1,2,4-trichlorobenzene containing 0.1 ppm 2,6-di-tert-butyl-4-methylphenol (BHT) by an autosampler at 150 °C. After 1.5 hours, the polymer solution was eluted through the TREF column, crystallized from 140 °C to 25 °C at a cooling rate of 0.5 °C / min, and then the fraction was eluted at a stepwise increasing temperature. From the 2D (molecular weight-temperature) and 3D (molecular weight-temperature-content percentage) diagrams of CFC, it can be clearly seen that there are two components distributed in the high temperature zone (80-130 ℃) and the low temperature zone (0-40 ℃). The low temperature zone component is an impurity, the high temperature zone component is a block copolymer, and the content of the high temperature zone component is the content (purity) of the block copolymer in the product.

[0082] (2) The molar ratio of the structural unit derived from propylene, the structural unit derived from ethylene, and the structural unit derived from the monomer containing a phosphonic acid group and a carbon-carbon double bond in the second block:

[0083] High temperature testing using BrukerAVANCE IIITM HD 400 MHz NMR spectrometer 13 C { 1 H} NMR spectrum. The test was conducted at 120 °C with 1,1,2,2-tetrachloroethane-d2 (1,1,2,2-TCE-d2) as the deuterated reagent. The test sample was the high temperature region component obtained by elution using a cross-fractionation chromatograph (CFC) in the test (1) above.

[0084] The peak at around 21.94 ppm can be considered as the signal of pentalinked isotactic polypropylene PPPPP, the peak at around 46.6 ppm can be considered as the signal of tetralinked isotactic polypropylene PPPP, and the peak at around 28.97 ppm can be considered as the signal of trilinked isotactic polypropylene PPP. It is assumed that the above three signals all belong to the signals of the first block, and the remaining signals all belong to the signals of the second block. The sum of the peak area integrals of the remaining signals is calculated and recorded as S The peak at around 11.98 ppm can be considered as the hydroxyl signal in the phosphonic acid group. The peak area integral is calculated and recorded as S1. The molar ratio of the structural units derived from ethylene and propylene in the second block is calculated according to the method described in J. Polym. Sci., Part C: Polym. Rev. 1989, 29, 201-317, pages 237-256. For example, the peaks at 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm can be considered as the signals of random copolymerization of ethylene and propylene such as EPEPE+EPEPE, EPEE+EEPE, PPEE+EEPP, PEEP, PEEE+EEEP, and EEE, respectively. The sum of the peak area integrals of the signals corresponding to the structural units derived from ethylene and propylene is S - S 1. According to the molar ratio and S - S 1 The signal peak area integral from the structural unit of ethylene is calculated as S 2, the peak area integral of the signal from the structural unit of propylene is S 3. S 3: S 2: S 1 is the molar ratio of the structural unit derived from propylene, the structural unit derived from ethylene and the structural unit derived from the monomer containing a phosphonic acid group and a carbon-carbon double bond.

[0085] (3) Number average molecular weight and molecular weight distribution of the first block, the second block and the propylene-based olefin block copolymer having flame retardant function:

[0086] The number average molecular weight and molecular weight distribution (PDI) were determined by high temperature gel permeation chromatography (high temperature GPC). The chromatographic column was PLgel Olexis 300 mm×7.5 mm×13 μm (3 columns connected in series). The mobile phase was 1,2,4-trichlorobenzene (1,2,4-TCB) containing 2,6-di-tert-butyl-4-methylphenol (BHT, 200 mg / L) as a stabilizer, and the flow rate was 1.0 mL / min. The test temperature was 150 °C. The test sample was a polymer solution with a mass concentration of 50 mg / ml prepared using the mobile phase as a solvent, and the injection volume was 10 μL. The polymer tested was the high temperature region component obtained after elution using a cross-fractionation chromatograph (CFC) in the test (1) above. The molecular weight obtained was calibrated with the polystyrene standard Easi-Cal PS-1 (PL Company).

[0087] The number average molecular weight of the first block is determined by the above method for the product obtained by only the first polymerization reaction, and the number average molecular weight of the second block is obtained by subtracting the number average molecular weight of the first block from the number average molecular weight of the final block copolymer. The product obtained by the first polymerization reaction is obtained by precipitating, solid-liquid separation, washing and drying the mixed system after the first polymerization reaction.

[0088] (4) Content of the first block and the second block:

[0089] The contents of the first block and the second block are respectively the percentages of the number average molecular weight of the first block and the number average molecular weight of the second block in the number average molecular weight of the block copolymer.

[0090] (5) Isotacticity of isotactic polypropylene block:

[0091] For isotacticity 13 C NMR spectrometry. A Bruker 600 MHz high temperature NMR spectrometer was used. 50 mg of sample was added to the NMR tube, and then 0.6 mL of deuterated o-dichlorobenzene was added. The sample was heated and dissolved with a hot air gun, and after mixing evenly, the sample was tested at 120 °C. The sample was the product obtained from the first polymerization reaction.

[0092] (6) Limiting oxygen index:

[0093] The limiting oxygen index is tested according to the method described in GB 2406.2-2009. The limiting oxygen index refers to the minimum oxygen concentration required for the sample to maintain stable combustion in a mixed gas flow of oxygen and nitrogen under specified test conditions. Specifically, the test steps include: fixing the sample vertically in a glass combustion tube, and its base is connected to a device that can generate a nitrogen-oxygen mixed gas flow; igniting the top of the sample, the oxygen concentration in the mixed gas flow will continue to decrease until the flame is extinguished; the oxygen concentration when the flame just goes out is the limiting oxygen index. Five samples of each material need to be tested and the average value is taken. Each sample is required to be flat and smooth, without bubbles. The size of the sample is: length 120mm, width 10.0mm, thickness 4mm.

[0094] (7) Flame retardant grade:

[0095] The flame retardancy level is tested according to the method described in the vertical burning test in UL94-2018. Specifically, the test steps include: test sample preparation, sample pretreatment, flame rating assessment and test equipment. The test classifies materials into V-0, V-1, V-2, and NR levels, among which V-0 has the highest flame retardancy level and NR represents no flame retardancy level.

[0096] (8) Tensile strength and elongation at break:

[0097] The tensile strength and elongation at break were tested using an Instron 3367 universal testing machine. The test was performed according to the method described in ASTM D1708-13. Dumbbell-shaped samples with a width of 5 mm and a thickness of 0.5 mm were used. The tensile test was repeated at least five times for each sample and the average value was taken. The tensile test was performed at a tensile speed of 10 mm / min.

[0098] Example 1

[0099] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityl tetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50°C and 0.2 MPa. After the reaction lasted for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0100] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and simultaneously adding vinylphosphonic acid at a rate of 0.6 g / min, and carrying out a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, stopping the addition of vinylphosphonic acid, and simultaneously stopping the introduction of ethylene gas and propylene gas; subsequently, reducing the pressure of the reactor to normal pressure, to obtain a mixed system after the second polymerization reaction;

[0101] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0102] The structure of the hafnium pyridine imine is shown below:

[0103] .

[0104] The hafnium pyridine imine can be prepared by a method disclosed in the prior art, such as the preparation method disclosed in 2.2.4 of the paper reported by Yin Xiao (Yin Xiao. Preparation of stereoblock polypropylene by chain shuttling polymerization [D]. Tianjin University, 2020.).

[0105] The product of this embodiment contains a propylene-based olefin block copolymer with flame retardant function, and the block copolymer contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.8%; the second block contains a random copolymer block of propylene, ethylene and vinyl phosphonic acid; the total mass of the prepared product is 12.2 g; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 24.1%, and the content of the second block is 75.9%. The molar ratio of the structural units from propylene, the structural units from ethylene and the structural units from the monomers of vinyl phosphonic acid in the second block is 5:1.8:0.6. The number average molecular weight of the first block is 22 kDa. The number average molecular weight of the second block is 69.3 kDa. The number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 91.3 kDa, and the molecular weight distribution is 2.65.

[0106] The cross-fractionation chromatograph (CFC) described in the test method (1) above was used to test the mass content (purity) of the flame-retardant propylene-based olefin block copolymer of this embodiment in the product to be 91.4%. The nuclear magnetic resonance spectrometer described in the test method (2) above was used to test the peaks at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 11.98 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the flame-retardant propylene-based olefin block copolymer of this embodiment contains the first block and the second block.

[0107] The flame retardant propylene-based olefin block copolymer has a limiting oxygen index of 32% and a flame retardancy grade of V-0 of UL94. It should be noted that the limiting oxygen index and flame retardancy grade here are tested on the product prepared in the example (unpurified), and the same is true for the following examples and comparative examples.

[0108] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the flame-retardant propylene-based olefin block copolymer of this embodiment are added to the extruder in a mass ratio of 40:40:20, mixed for 7 minutes at 200 ° C and 100 rpm, and the mixed eutectic is extruded and cooled in air to obtain ethylene-propylene recycled plastics to which a compatibilizer with flame-retardant effect is added. It should be noted that the flame-retardant propylene-based olefin block copolymer added here is the product prepared in the embodiment (not purified), and the same is true for the following embodiments and comparative examples.

[0109] The scanning electron microscope image of the recycled plastic is shown in Figure 1 shown.

[0110] Example 2

[0111] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityl tetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50°C and 0.2 MPa. After the reaction lasted for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0112] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and simultaneously dropping vinyl phosphonic acid at a rate of 0.7 g / min, and carrying out a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, the dropping of vinyl phosphonic acid is stopped, and the introduction of ethylene gas and propylene gas is also stopped; subsequently, the pressure of the reactor is reduced to normal pressure to obtain a mixed system after the second polymerization reaction;

[0113] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0114] The structure of the hafnium pyridine imine is shown below:

[0115] .

[0116] The product of this embodiment contains a propylene-based olefin block copolymer with flame retardant function, and the block copolymer contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.5%; the second block contains a random copolymer block of propylene, ethylene and vinyl phosphonic acid; the total mass of the prepared product is 12.4 g; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 23.7%, and the content of the second block is 76.3%. The molar ratio of the structural unit from propylene, the structural unit from ethylene and the structural unit from vinyl phosphonic acid in the second block is 5:1.5:0.88. The number average molecular weight of the first block is 22 kDa. The number average molecular weight of the second block is 70.8 kDa. The number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 92.8 kDa, and the molecular weight distribution is 2.8.

[0117] By testing with the cross-fractionation chromatograph (CFC) described in the test method (1) above, the mass content of the propylene-based olefin block copolymer with flame retardant function in the product of the present embodiment is 90.2%. By testing with the nuclear magnetic resonance spectrometer described in the test method (2) above, peaks are observed at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 11.98 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the propylene-based olefin block copolymer with flame retardant function of the present embodiment contains the above-mentioned first block and second block.

[0118] The flame retardant propylene-based olefin block copolymer has a limiting oxygen index of 33% and a flame retardant grade of V-0 of UL94.

[0119] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the propylene-based olefin block copolymer with flame retardant function of this embodiment were added into an extruder in a mass ratio of 40:40:20, mixed for 7 minutes at 200°C and 100rpm, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastic added with a compatibilizer with flame retardant effect.

[0120] The scanning electron microscope image of the recycled plastic is shown in Figure 2 shown.

[0121] Example 3

[0122] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityl tetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50°C and 0.2 MPa. After the reaction lasted for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0123] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and simultaneously dropping vinylphosphonic acid at a rate of 0.8 g / min, and conducting a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, the dropping of vinylphosphonic acid was stopped, and the introduction of ethylene gas and propylene gas was also stopped; subsequently, the pressure of the reactor was reduced to normal pressure, and a mixed system after the second polymerization reaction was obtained;

[0124] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0125] The structure of the hafnium pyridine imine is shown below:

[0126] .

[0127] The product of this embodiment contains a propylene-based olefin block copolymer with flame retardant function, and the block copolymer contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.8%; the second block contains a random copolymer block of propylene, ethylene and vinylphosphonic acid; the total mass of the prepared product is 12.8 g; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 23.0%, and the content of the second block is 77.0%. The molar ratio of the structural unit from propylene, the structural unit from ethylene and the structural unit from vinylphosphonic acid in the second block is 5:1:1.06. The number average molecular weight of the first block is 22 kDa. The number average molecular weight of the second block is 73.7 kDa. The number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 95.7 kDa, and the molecular weight distribution is 2.74.

[0128] By testing with the cross-fractionation chromatograph (CFC) described in the test method (1) above, the mass content of the propylene-based olefin block copolymer with flame retardant function in the product of the present embodiment is 88.6%. By testing with the nuclear magnetic resonance spectrometer described in the test method (2) above, peaks are observed at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 11.98 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the propylene-based olefin block copolymer with flame retardant function of the present embodiment contains the above-mentioned first block and second block.

[0129] The flame retardant propylene-based olefin block copolymer has a limiting oxygen index of 34.5% and a flame retardant grade of V-0 of UL94.

[0130] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the propylene-based olefin block copolymer with flame retardant function of this embodiment were added into an extruder in a mass ratio of 40:40:20, mixed for 7 minutes at 200°C and 100rpm, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastic added with a compatibilizer with flame retardant effect.

[0131] The scanning electron microscope image of the recycled plastic is shown in Figure 3 shown.

[0132] Example 4

[0133] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityl tetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50°C and 0.2 MPa. After the reaction lasted for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0134] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and simultaneously adding vinylphosphonic acid at a rate of 1.0 g / min, and carrying out a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, stopping the addition of vinylphosphonic acid and stopping the introduction of ethylene gas and propylene gas; subsequently, reducing the pressure of the reactor to normal pressure to obtain a mixed system after the second polymerization reaction;

[0135] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0136] The structure of the hafnium pyridine imine is shown below:

[0137] .

[0138] The product of this embodiment contains a propylene-based olefin block copolymer with flame retardant function, and the block copolymer contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.5%; the second block contains a random copolymer block of propylene, ethylene and vinylphosphonic acid; the total mass of the prepared product is 13.6 g; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 21.6%, and the content of the second block is 78.4%. The molar ratio of the structural units from propylene, the structural units from ethylene and the structural units from vinylphosphonic acid in the second block is 5:1:1.98. The number average molecular weight of the first block is 22 kDa. The number average molecular weight of the second block is 79.9 kDa. The number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 101.9 kDa, and the molecular weight distribution is 2.91.

[0139] By testing with the cross-fractionation chromatograph (CFC) described in the test method (1) above, the mass content of the propylene-based olefin block copolymer with flame retardant function in the product of the present embodiment is 85.7%. By testing with the nuclear magnetic resonance spectrometer described in the test method (2) above, peaks are observed at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 11.98 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the propylene-based olefin block copolymer with flame retardant function of the present embodiment contains the above-mentioned first block and second block.

[0140] The flame retardant propylene-based olefin block copolymer has a limiting oxygen index of 37% and a flame retardant grade of V-0 of UL94.

[0141] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the propylene-based olefin block copolymer with flame retardant function of this embodiment were added into an extruder in a mass ratio of 40:40:20, mixed for 7 minutes at 200°C and 100rpm, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastic added with a compatibilizer with flame retardant effect.

[0142] The scanning electron microscope image of the recycled plastic is shown in Figure 4 shown.

[0143] Example 5

[0144] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 2.0 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityltetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50° C. and 0.2 MPa. After reacting for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0145] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and simultaneously adding vinylphosphonic acid at a rate of 1.0 g / min, and carrying out a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, stopping the addition of vinylphosphonic acid and stopping the introduction of ethylene gas and propylene gas; subsequently, reducing the pressure of the reactor to normal pressure to obtain a mixed system after the second polymerization reaction;

[0146] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0147] The structure of the hafnium pyridine imine is shown below:

[0148] .

[0149] The product of this embodiment contains a propylene-based olefin block copolymer with flame retardant function, and the block copolymer contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.8%; the second block contains a random copolymer block of propylene, ethylene and vinylphosphonic acid; the total mass of the prepared product is 13.8 g; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 21.7%, and the content of the second block is 78.3%. The molar ratio of the structural units from propylene, the structural units from ethylene and the structural units from vinylphosphonic acid in the second block is 5:1:1.86. The number average molecular weight of the first block is 17.3 kDa. The number average molecular weight of the second block is 62.6 kDa. The number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 79.9 kDa, and the molecular weight distribution is 2.5.

[0150] By testing with the cross-fractionation chromatograph (CFC) described in the test method (1) above, the mass content of the propylene-based olefin block copolymer with flame retardant function in the product of the present embodiment is 86.0%. By testing with the nuclear magnetic resonance spectrometer described in the test method (2) above, it is observed that peaks appear at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 11.98 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the propylene-based olefin block copolymer with flame retardant function of the present embodiment contains the above-mentioned first block and second block.

[0151] The flame retardant propylene-based olefin block copolymer has a limiting oxygen index of 36.5% and a flame retardant grade of V-0 of UL94.

[0152] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the propylene-based olefin block copolymer with flame retardant function of this embodiment were added into an extruder in a mass ratio of 40:40:20, mixed for 7 minutes at 200°C and 100rpm, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastic added with a compatibilizer with flame retardant effect.

[0153] Example 6

[0154] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityl tetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50°C and 0.2 MPa. After the reaction lasted for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0155] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and simultaneously adding vinylphosphonic acid at a rate of 1.2 g / min, and carrying out a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, stopping the addition of vinylphosphonic acid and stopping the introduction of ethylene gas and propylene gas; subsequently, reducing the pressure of the reactor to normal pressure to obtain a mixed system after the second polymerization reaction;

[0156] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0157] The structure of the hafnium pyridine imine is shown below:

[0158] .

[0159] The product of this embodiment contains a propylene-based olefin block copolymer with flame retardant function, and the block copolymer contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.8%; the total mass of the prepared product is 14.4 g; the second block contains a random copolymer block of propylene, ethylene and vinylphosphonic acid; based on the total number average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 20.4%, and the content of the second block is 79.6%. The molar ratio of the structural units from propylene, the structural units from ethylene and the structural units from vinylphosphonic acid in the second block is 4:1:3.12. The number average molecular weight of the first block is 22 kDa. The number average molecular weight of the second block is 85.8 kDa. The number average molecular weight of the propylene-based olefin block copolymer with flame retardant function is 107.8 kDa, and the molecular weight distribution is 2.82.

[0160] By testing with the cross-fractionation chromatograph (CFC) described in the test method (1) above, the mass content of the propylene-based olefin block copolymer with flame retardant function in the product of the present embodiment is 85.0%. By testing with the nuclear magnetic resonance spectrometer described in the test method (2) above, it is observed that peaks appear at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 11.98 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the propylene-based olefin block copolymer with flame retardant function of the present embodiment contains the above-mentioned first block and second block.

[0161] The flame retardant propylene-based olefin block copolymer has a limiting oxygen index of 39% and a flame retardant grade of V-0 of UL94.

[0162] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the propylene-based olefin block copolymer with flame retardant function of this embodiment were added into an extruder in a mass ratio of 40:40:20, mixed for 7 minutes at 200°C and 100rpm, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastic added with a compatibilizer with flame retardant effect.

[0163] The scanning electron microscope image of the recycled plastic is shown in Figure 5 shown.

[0164] Comparative Example 1

[0165] This comparative example is substantially the same as Example 1, except that no vinylphosphonic acid is added.

[0166] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene was added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityl tetrakis(pentafluorophenyl)borate were added to the toluene; propylene gas was introduced into the reaction kettle, and a polymerization reaction was carried out at 50° C. and 0.2 MPa. After reacting for 5 minutes, the propylene gas was quickly released to obtain a mixed system after the first polymerization reaction;

[0167] (2) under anhydrous and oxygen-free conditions, introducing ethylene gas and propylene gas at a molar ratio of 1:1 into the mixed system after the first polymerization reaction obtained in step (1), maintaining the pressure of the reactor at 0.2 MPa, and conducting a polymerization reaction at 50° C. and 0.2 MPa. After reacting for 10 minutes, the introduction of ethylene gas and propylene gas was stopped; then, the pressure of the reactor was reduced to normal pressure to obtain a mixed system after the second polymerization reaction;

[0168] (3) after the mixed system after the second polymerization reaction obtained in step (2) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0169] The structure of the hafnium pyridine imine is the same as that in Example 1.

[0170] The product of this comparative example contains a propylene-based olefin block copolymer, which contains: a first block and a second block; the first block contains an isotactic polypropylene block, and its isotacticity is 94.8%; the second block contains a copolymer block of propylene and ethylene; the total mass of the prepared product is 11.9 g; based on the total number average molecular weight of the propylene-based olefin block copolymer as 100%, the content of the first block is 24.7%, and the content of the second block is 75.3%. The molar ratio of the structural unit derived from propylene to the structural unit derived from ethylene in the second block is 5:2. The number average molecular weight of the first block is 22 kDa. The number average molecular weight of the second block is 67 kDa. The number average molecular weight of the propylene-based olefin block copolymer is 89 kDa.

[0171] The cross-fractionation chromatograph (CFC) described in the test method (1) above was used to test the mass content of the propylene-based olefin block copolymer of this comparative example in the product to be 95.1%. The nuclear magnetic resonance spectrometer described in the test method (2) above was used to test the peaks at positions such as 21.94 ppm, 46.6 ppm, 28.97 ppm, 37.94 ppm, 37.58 ppm, 37.50 ppm, 30.76 ppm, 30.38 ppm, and 29.98 ppm, confirming that the propylene-based olefin block copolymer of this comparative example contained the first block and the second block.

[0172] The limiting oxygen index of the propylene-based olefin block copolymer is 15%, and the flame retardant grade is NR grade of UL94.

[0173] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the propylene-based olefin block copolymer of this comparative example were added into an extruder in a mass ratio of 40:40:20, mixed at 200°C and 100rpm for 7 minutes, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastics with a compatibilizer added.

[0174] The scanning electron microscope image of the recycled plastic is shown in Figure 6 shown.

[0175] Comparative Example 2

[0176] No compatibilizer was added to the recycled plastic in this comparative example.

[0177] High-density polyethylene (Sabic B4660) and isotactic polypropylene (Dow chemical H314-02Z) were added into the extruder at a mass ratio of 40:40, mixed at 200 °C and 100 rpm for 7 minutes, and then the mixed blend was extruded and cooled in air to obtain ethylene-propylene recycled plastic.

[0178] The scanning electron microscope image of the recycled plastic is shown in Figure 7 shown.

[0179] Comparative Example 3

[0180] This comparative example uses a random copolymer of propylene, ethylene and vinylphosphonic acid as a compatibilizer.

[0181] (1) Under anhydrous and oxygen-free conditions, 250 ml of toluene is added to a reaction kettle, and then 1.5 mmol of triisobutylaluminum, 10 μmol of hafnium pyridine imine and 20 μmol of trityltetrakis(pentafluorophenyl)borate are added to the toluene; ethylene gas and propylene gas with a molar ratio of 1:1 are introduced into the reaction kettle, and vinylphosphonic acid is added dropwise at a rate of 0.67 g / min, and a polymerization reaction is carried out at 50° C. and 0.2 MPa. After the reaction lasts for 15 minutes, the addition of vinylphosphonic acid is stopped, and the introduction of ethylene gas and propylene gas is stopped at the same time; then, the pressure of the reaction kettle is reduced to normal pressure to obtain a mixed system after the polymerization reaction;

[0182] (2) after the mixed system after the polymerization reaction obtained in step (1) is transferred out of the reactor, ethanol is added for precipitation, and the precipitate is filtered, washed and dried to obtain a product;

[0183] The structure of the hafnium pyridine imine is the same as that in Example 1.

[0184] The product of this comparative example contains a random copolymer of propylene, ethylene and vinylphosphonic acid, wherein the molar ratio of the structural unit derived from propylene, the structural unit derived from ethylene and the structural unit derived from vinylphosphonic acid in the random copolymer is 5:1:2.05. The number average molecular weight of the random copolymer of propylene, ethylene and vinylphosphonic acid is 103 kDa.

[0185] The random copolymer of propylene, ethylene and vinylphosphonic acid has a limiting oxygen index of 37% and a flame retardant grade of V-0 of UL94.

[0186] High-density polyethylene (Sabic B4660), isotactic polypropylene (Dow chemical H314-02Z) and the random copolymer of propylene, ethylene and vinylphosphonic acid of this comparative example were added into an extruder in a mass ratio of 40:40:20, mixed at 200°C and 100rpm for 7 minutes, and then the mixed co-melt was extruded and cooled in air to obtain ethylene-propylene recycled plastic added with a compatibilizer having a flame retardant effect.

[0187] Comparative Example 4

[0188] This comparative example is basically the same as Example 1, except that the main catalyst hafnium pyridine imine in Example 1 is replaced by a metallocene catalyst, and the amount used is the same as that in Example 1. The metallocene catalyst is dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride, and its structure is shown below:

[0189] .

[0190] The product prepared in this comparative example is different from that in Example 1. Only the first block, namely the polypropylene block, can be prepared, with a mass of 2 g and a number average molecular weight of 15 kDa. The propylene-based olefin block copolymer with flame retardant function of Example 1 cannot be prepared.

[0191] The samples of the recycled plastics obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were tested for mechanical properties, vertical combustion and limiting oxygen index. The test results are shown in Table 1.

[0192] Table 1

[0193]

[0194] It can be seen from Table 1 that when the propylene-based olefin block copolymers with flame retardant function according to the embodiments of the present invention are used as a compatibilizer in ethylene-propylene recycled plastics, the recycled plastics have both excellent mechanical properties and flame retardant properties.

[0195] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the present invention are still within the scope of protection of the present invention.

Claims

1. A propylene-based olefin block copolymer having flame retardant function, characterized in that: Containing: a first block and a second block; the first block contains a polypropylene block, and the second block contains a copolymer block of propylene, ethylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond; based on the total average molecular weight of the propylene-based olefin block copolymer with flame retardant function as 100%, the content of the first block is 20-30%, and the content of the second block is 70-80%; The molar ratio of the structural unit derived from propylene, the structural unit derived from ethylene and the structural unit derived from the monomer containing a phosphonic acid group and a carbon-carbon double bond in the second block is (4-5): (1-2): (0.6-3.5); The monomer containing a phosphonic acid group and a carbon-carbon double bond includes one or more of vinylphosphonic acid, methyl vinylphosphonate, dimethyl vinylphosphonate, ethyl vinylphosphonate and diethyl vinylphosphonate.

2. The propylene-based olefin block copolymer with flame retardant function according to claim 1, characterized in that: The ratio of the number average molecular weights of the first block and the second block is 1:(3-4).

3. The propylene-based olefin block copolymer with flame retardant function according to claim 1, characterized in that: The first block contains an isotactic polypropylene block, and the isotacticity of the isotactic polypropylene block is 85-95%.

4. The propylene-based olefin block copolymer with flame retardant function according to claim 1, characterized in that: The number average molecular weight of the first block is 15-30 kDa.

5. The propylene-based olefin block copolymer with flame retardant function according to claim 1, characterized in that: The number average molecular weight of the second block is 60-90 kDa.

6. The propylene-based olefin block copolymer with flame retardant function according to claim 1, characterized in that: The number average molecular weight of the flame retardant propylene-based olefin block copolymer is 75-120 kDa, and the molecular weight distribution is 1.9-3.

0.

7. The propylene-based olefin block copolymer with flame retardant function according to claim 1, characterized in that: The limiting oxygen index of the flame-retardant propylene-based olefin block copolymer is 30-40%, and the flame retardant grade of the flame-retardant propylene-based olefin block copolymer is V-0 of UL94.

8. A method for preparing the propylene-based olefin block copolymer with flame retardant function according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Under anhydrous and oxygen-free condition, subjecting propylene to a first polymerization reaction in an organic solvent in the presence of a main catalyst, a co-catalyst and a chain transfer agent to obtain a mixed system after the first polymerization reaction; (2) adding ethylene, propylene and a monomer containing a phosphonic acid group and a carbon-carbon double bond to the mixed system after the first polymerization reaction under anhydrous and oxygen-free conditions to carry out a second polymerization reaction to obtain a mixed system after the second polymerization reaction; (3) subjecting the mixed system after the second polymerization reaction to at least precipitation and solid-liquid separation to obtain the propylene-based olefin block copolymer having a flame retardant function; The main catalyst comprises a complex of a ligand containing pyridine and imine and a transition metal of Group IVB, the co-catalyst comprises an organic boron compound, and the chain transfer agent comprises an alkyl aluminum compound and / or an alkyl zinc compound.

9. The preparation method according to claim 8, characterized in that The temperature of the first polymerization reaction is 25-70° C., and the pressure is 0.1-0.5 MPa.

10. The preparation method according to claim 8, characterized in that The main catalyst includes a complex having a structure as shown in Formula I and / or Formula II: Formula I Formula II wherein M is selected from one of the Group IVB transition metals; R1 and R2 are each independently selected from a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group and a substituted or unsubstituted polycyclic aromatic group.

11. The preparation method according to claim 8, characterized in that: The co-catalyst includes one or more of trityltetrakis(pentafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate and tetra-n-butylammoniumtetraphenylborate.

12. The preparation method according to claim 8, characterized in that: The chain transfer agent includes one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylzinc, methylaluminoxane, modified methylaluminoxane, ethylaluminoxane and isobutylaluminoxane.

13. The preparation method according to claim 8, characterized in that: The molar ratio of the main catalyst to the chain transfer agent is 1:(150-200).

14. The preparation method according to claim 8, characterized in that The temperature of the second polymerization reaction is 25-70° C., and the pressure is 0.1-0.5 MPa.

15. A composition comprising recycled plastic, characterized in that include: Polyethylene recycled plastic, polypropylene recycled plastic and a compatibilizer, wherein the compatibilizer comprises a propylene-based olefin block copolymer with flame retardant function as described in any one of claims 1 to 7; wherein the mass ratio of the total amount of the polyethylene recycled plastic and the polypropylene recycled plastic to the compatibilizer is 8:(1~2).

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