A multiphase composite material and its preparation method and application

Abstract

The present invention belongs to the field of polymers and relates to a multiphase composite material and its preparation method and application. The multiphase composite material comprises polypropylene (A) and a polyolefin elastomer (B) grafted with an olefinic functional monomer; wherein, based on the total weight of the multiphase composite material, the xylene soluble content of the multiphase composite material is 15 to 75 wt%; the content of structural units derived from olefinic functional monomers in a grafted state in the multiphase composite material is 0.4 to 8 wt%; the flexural modulus of the multiphase composite material is 200 to 1000 MPa; and the D50 of the grafted phase derived from the olefinic functional monomer is less than 300 nm. The multiphase composite material of the present invention can take into account both mechanical and electrical properties at higher operating temperatures and is suitable for high temperature and high operating field strength working conditions.

Description

Technical Field

[0001] The present invention belongs to the field of polymers, and in particular relates to a multiphase composite material, a preparation method of the multiphase composite material, and applications of the multiphase composite material. Background Art

[0002] With the sustained and rapid development of my country's economy and the continuous improvement of people's living standards, the demand for electricity is also growing rapidly. Solving the problem of channels for the transmission of electric energy and delivering large amounts of electric energy to users is one of the major issues that need to be urgently addressed in the development of the power industry. In order to address this issue, my country has established the basic development direction of building and developing ultra-high voltage, large-capacity AC and DC transmission systems. In the development of extruded plastic insulated cables, the most important key issue is the development of cable insulation materials. Traditional extruded DC cables generally use cross-linked polyethylene (XLPE) as the cable insulation material.

[0003] The traditional method of disposing of discarded XLPE cable insulation is incineration, which not only wastes energy but also produces other environmental problems such as greenhouse gases. In addition, XLPE cables require cross-linking and degassing during production, which produce pollutants such as harmful gases and waste a lot of energy. Therefore, how to improve the environmental friendliness and compatibility of power cable insulation materials has become an important issue in the development of power cable insulation materials. In recent years, in order to address this issue and meet the requirements of environmental protection and sustainable development, many institutions and scholars have begun research on new recyclable non-cross-linked polyolefin cable insulation materials.

[0004] Polypropylene-based materials, as cable insulation, offer the inherent advantages of high operating temperatures and high breakdown field strengths, along with space charge suppression and recyclability. These materials have become a key area of development for non-cross-linked polyolefin insulation materials. Blending polypropylene with polyolefin elastomers and ethylene-propylene copolymers has effectively improved the brittleness of polypropylene while retaining its excellent thermal and electrical properties. Nanoparticle doping is an effective approach to improving the electrical insulation properties of polypropylene. However, the tendency of nanoparticles to agglomerate, leading to a decrease in insulation performance, has limited the widespread application of this approach in practical engineering applications.

[0005] Therefore, it is necessary to find a new type of polypropylene material with stable performance and easy preparation to adapt to applications under higher temperatures and high field strengths. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a multiphase composite material which can take into account both mechanical and electrical properties at higher operating temperatures and is suitable for high temperature and high operating field strength conditions.

[0007] The first aspect of the present invention provides a multiphase composite material, which includes polypropylene (A) grafted with an olefinic functional monomer and a polyolefin elastomer (B); wherein, based on the total weight of the multiphase composite material, the xylene soluble content of the multiphase composite material is 15 to 75 wt%, preferably 20 to 60 wt%, and more preferably 25 to 55 wt%; the content of structural units derived from the olefinic functional monomer in a grafted state in the multiphase composite material is 0.4 to 8 wt%, preferably 1 to 5 wt%; the flexural modulus of the multiphase composite material is 200 to 1000 MPa; and the D50 of the grafted phase derived from the olefinic functional monomer is less than 300 nm.

[0008] The second aspect of the present invention provides a method for preparing the above-mentioned multiphase composite material, comprising the following steps: blending polypropylene (A) graft-modified with an olefin-containing functional monomer with a polyolefin elastomer (B) to prepare the multiphase composite material.

[0009] The third aspect of the present invention provides use of the multiphase composite material.

[0010] The multiphase composite material of the present invention can balance mechanical and electrical properties at relatively high operating temperatures and is suitable for high-temperature, high-field-strength operating conditions. Compared with polypropylene materials obtained by in-reactor alloying, the mechanical blending of polypropylene materials with polyolefin elastomers yields products with more diverse structures and greater controllability, thereby achieving better performance. Compared with nano-doping technology, the olefin-functional monomer polymer introduced by dispersed grafting modification can form a uniformly distributed nanoscale dispersed phase in the composite material, i.e., a type of organic nanoparticle, thereby avoiding the problem of inorganic nanoparticles being difficult to add and disperse. In addition, compared with materials incorporating small molecule additives, the grafted modified polypropylene material of the present invention avoids the performance degradation caused by small molecule migration and thus has better stability.

[0011] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0013] Figure 1 This is an atomic force microscope photograph of the product in Example 1, wherein the bright white portion indicated by the circle is the styrene grafted phase, the black portion is the rubber phase, and the other portions are the continuous phase.

[0014] Figure 2 This is a microstructure photograph of the product in Example 1 under a 10,000x electron microscope, in which the spherical dispersed phase is the styrene grafted phase.

[0015] Figure 3 This is a microstructure photograph of the product in Example 2 under a 10,000x electron microscope.

[0016] Figure 4 This is a microstructure photograph of the product in Example 3 under a 10,000x electron microscope.

[0017] Figure 5 This is a microstructure photograph of the product in Example 4 under a 10,000x electron microscope.

[0018] Figure 6 This is a microstructure photograph of the product in Comparative Example 3 under a 10,000x electron microscope.

[0019] Figure 7 This is a microstructure photograph of the product in Comparative Example 3 after etching under a 10,000x electron microscope. The black part is the rubber phase.

[0020] Figure 8 This is a microstructure photograph of the product in Comparative Example 4 under a 10,000x electron microscope.

[0021] Figure 9 This is a microstructure photograph of the product in Comparative Example 5 under a 10,000x electron microscope. DETAILED DESCRIPTION

[0022] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0023] The present invention provides a multiphase composite material, which comprises polypropylene (A) graft-modified with an olefinic functional monomer and a polyolefin elastomer (B); wherein, based on the total weight of the multiphase composite material, the xylene soluble content of the multiphase composite material is 15 to 75 wt%, preferably 20 to 60 wt%, and more preferably 25 to 55 wt%; the content of structural units derived from the olefinic functional monomer in a grafted state in the multiphase composite material is 0.4 to 8 wt%, preferably 1 to 5 wt%; the flexural modulus of the multiphase composite material is 200 to 1000 MPa, preferably 200 to 700 MPa, and more preferably 250 to 600 MPa; and the D50 of the graft phase derived from the olefinic functional monomer is less than 300 nm, preferably 10 to 250 nm, and more preferably 50 to 220 nm.

[0024] In the present invention, the multiphase composite material has a phase-separated structure, comprising a continuous propylene phase, a rubber phase, and a graft phase derived from an olefinic-functional monomer dispersed within the continuous propylene phase. The polypropylene (A) graft-modified with an olefinic-functional monomer provides at least the continuous propylene phase and the graft phase; the polyolefin elastomer (B) provides the rubber phase. The meaning of "continuous phase" is well known to those skilled in the art and refers to the matrix portion. The "rubber phase" refers to the soft, xylene-soluble portion. The "graft phase" is formed from structural units derived from the olefinic-functional monomer, which are derived from the grafted polypropylene (A). Therefore, structural units derived from the olefinic-functional monomer "in a grafted state" refer to structural units derived from the olefinic-functional monomer that are covalently bonded (grafted) to the polypropylene. The multiphase structure can be observed using an atomic force microscope. The black portion observed under an atomic force microscope is the rubber phase, the bright white portion is the graft phase, and the remaining portion is the continuous phase. The graft phase can also be directly observed using an electron microscope (dispersed phase in an electron microscope image).

[0025] According to the present invention, preferably, the multiphase composite material has at least one of the following characteristics: a melt flow rate at 230°C and a load of 2.16 kg of 0.5 to 15 g / 10 min, preferably 1 to 10 g / 10 min, further preferably 1.5 to 6 g / 10 min; an elongation at break ≥ 200%, preferably an elongation at break ≥ 300%; and a tensile strength greater than 5 MPa, preferably 10 to 25 MPa.

[0026] According to the present invention, preferably, the multiphase composite material has at least one of the following characteristics:

[0027] - The maximum operating temperature of the multiphase composite material is ≥90°C, preferably 100-160°C, more preferably 110-140°C;

[0028] - the multiphase composite material has a breakdown field strength Eg at 110°C of ≥ 290 kV / mm, preferably 300-800 kV / mm, more preferably 305-750 kV / mm; for example, 310 kV / mm, 320 kV / mm, 330 kV / mm, 340 kV / mm, 350 kV / mm, 400 kV / mm, 450 kV / mm, 500 kV / mm, 550 kV / mm, 600 kV / mm, 650 kV / mm, or 700 kV / mm;

[0029] - DC volume resistivity ρ of the multiphase composite material at 110°C and 40 kV / mm field strength vg ≥1.0×10 13 Ω·m, preferably 1.5×10 13 Ω·m~1.0×10 20Ω·m;

[0030] - The dielectric constant of the multiphase composite material at 110°C and 50 Hz is greater than 2.0, preferably 2.1 to 2.5.

[0031] The alkenyl group in the alkenyl functional monomer of the present invention is used for grafting with polypropylene. Therefore, any alkenyl functional monomer having an alkenyl group at a reactive position is applicable to the present invention.

[0032] Specifically, the alkenyl functional monomer is selected from at least one monomer having a structure shown in Formula 1.

[0033]

[0034] In formula 1, R b 、R c 、R d are each independently selected from H, substituted or unsubstituted alkyl; R a is selected from substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, substituted or unsubstituted ester groups, substituted or unsubstituted carboxyl groups, substituted or unsubstituted cycloalkyl groups or heterocyclic groups, cyano groups, and substituted or unsubstituted silyl groups.

[0035] According to a preferred embodiment of the present invention, R b 、R c 、R d R a Selected from substituted or unsubstituted C1-C 20 Alkyl, substituted or unsubstituted C1-C 20 Alkoxy, substituted or unsubstituted C6-C 20 Aryl, substituted or unsubstituted C1-C 20 Ester group, substituted or unsubstituted C1-C 20 Carboxyl, substituted or unsubstituted C3-C 20 Cycloalkyl or heterocyclic group, cyano group, substituted or unsubstituted C3-C 20 Silane; the substituted group is halogen, hydroxyl, amino, C1-C 12 Alkyl, C3-C6 cycloalkyl, C1-C 12 Alkoxy, C1-C 12 of acyloxy.

[0036] According to a more preferred embodiment of the present invention, wherein R b 、R c 、R d Each is independently selected from H, substituted or unsubstituted C1-C6 alkyl;

[0037] Ra A group selected from the group represented by Formula 2, a group represented by Formula 3, a group represented by Formula 4, a group represented by Formula 5, a group represented by Formula 6, a combination of a group represented by Formula 6 and a group represented by Formula 7, and a heterocyclic group;

[0038]

[0039] In formula 2, R 4 -R 8 Each independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The substituted group is selected from halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Preferably, R 4 -R 8 Each is independently selected from H, halogen, hydroxy, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy;

[0040]

[0041] In formula 3, R4-R 10 Each independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The substituted group is selected from halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Preferably, R4-R 10Each is independently selected from H, halogen, hydroxy, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, and the substituted group is selected from halogen, hydroxy, amino, C1-C6 alkyl, C1-C6 alkoxy;

[0042]

[0043] In formula 4, R4'-R 10 ' are each independently selected from H, halogen, hydroxyl, amino, phosphate, sulfonic acid, substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The substituted group is selected from halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Preferably, R4'-R 10 'Each independently selected from H, halogen, hydroxy, amino, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, the substituted group is selected from halogen, hydroxy, amino, C1-C6 alkyl, C1-C6 alkoxy;

[0044]

[0045] In Formula 5, R', R", and R'" are each independently selected from substituted or unsubstituted C1-C 12 Straight chain alkyl, substituted or unsubstituted C3-C 12 branched alkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 acyloxy; preferably, R1 is a C2-C6 alkenyl, preferably a monounsaturated alkenyl; R2, R3, and R4 are each independently selected from a substituted or unsubstituted C1-C6 straight-chain alkyl, a substituted or unsubstituted C3-C6 branched-chain alkyl, a substituted or unsubstituted C1-C6 alkoxy, or a substituted or unsubstituted C1-C6 acyloxy;

[0046]

[0047] In formula 6, R mSelected from the following substituted or unsubstituted groups: C1-C 20 Straight chain alkyl, C3-C 20 Branched alkyl, C3-C 12 Cycloalkyl, C3-C 12 Epoxyalkyl, C3-C 12 Epoxyalkyl, the substituted group is selected from at least one of halogen, amino and hydroxyl;

[0048] The heterocyclic group is selected from imidazolyl, pyrazolyl, carbazolyl, pyrrolidinone, pyridyl, piperidinyl, caprolactam, pyrazinyl, thiazolyl, purinyl, morpholinyl, and oxazolinyl.

[0049] According to a specific embodiment of the present invention, the alkenyl-containing functional monomer is an aromatic olefin monomer, and the aromatic olefin monomer is selected from at least one of styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, monosubstituted or polysubstituted styrene, monosubstituted or polysubstituted α-methylstyrene, monosubstituted or polysubstituted 1-vinylnaphthalene and monosubstituted or polysubstituted 2-vinylnaphthalene; the substituted group is preferably selected from at least one of halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C8 straight-chain alkyl, C3-C8 branched alkyl or cycloalkyl, C1-C6 straight-chain alkoxy, C3-C8 branched alkoxy or cyclic alkoxy, C1-C8 straight-chain ester, C3-C8 branched ester or cyclic ester, C1-C8 straight-chain amine and C3-C8 branched amine or cyclic amine; preferably, the aromatic olefin monomer is selected from at least one of styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene and 4-methylstyrene.

[0050] According to a specific embodiment of the present invention, the alkenyl-containing functional monomer is an alkenyl-containing silane monomer, and the alkenyl-containing silane monomer is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltri-tert-butoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, ethylvinyldiethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, allyltriisopropoxysilane, vinyltri(β-methoxyethoxy)silane, allyltri(β-methoxyethoxy)silane, allyltri-tert-butoxysilane, allyltriacetoxysilane, methylallyldimethoxysilane and ethylallyldiethoxysilane.

[0051] According to a specific embodiment of the present invention, the alkenyl-functional monomer is an acrylate monomer and an optional acrylic acid monomer. Preferably, the acrylate monomer is selected from at least one of methyl (meth)acrylate, sec-butyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, dodecyl (meth)acrylate, coconut (meth)acrylate, octadecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and glycidyl (meth)acrylate. Preferably, the acrylic acid monomer is selected from at least one of acrylic acid, methacrylic acid, and 2-ethyl acrylic acid.

[0052] In the present invention, C3-C 12 The oxiranylalkyl group refers to an oxiranyl-substituted alkyl group having 3 to 12 carbon atoms, for example, oxiranylmethyl.

[0053] In the present invention, the structural unit derived from acrylic acid monomers may be absent or may coexist with the structural unit derived from acrylate monomers. Preferably, the molar ratio of the structural unit derived from acrylate monomers to the structural unit derived from acrylic acid monomers is 1:0-2, preferably 1:0.125-1.

[0054] According to a specific embodiment of the present invention, the alkenyl-containing functional monomer is an alkenyl-containing heterocyclic compound. The alkenyl-containing heterocyclic monomer of the present invention can be any alkenyl-containing heterocyclic compound that can be polymerized by free radicals, and can be selected from at least one of an imidazole containing an alkenyl substituent, a pyrazole containing an alkenyl substituent, a carbazole containing an alkenyl substituent, a pyrrolidone containing an alkenyl substituent, a pyridine or pyridinium salt containing an alkenyl substituent, a piperidine containing an alkenyl substituent, a caprolactam containing an alkenyl substituent, a pyrazine containing an alkenyl substituent, a thiazole containing an alkenyl substituent, a purine containing an alkenyl substituent, a morpholine containing an alkenyl substituent, and an oxazoline containing an alkenyl substituent; preferably, the alkenyl-containing heterocyclic monomer is a monoalkenyl-containing heterocyclic monomer.

[0055] Specifically, the alkenyl-containing heterocyclic monomer can be selected from: 1-vinylimidazole, 2-methyl-1-vinylimidazole, N-allylimidazole, 1-vinylpyrazole, 3-methyl-1-vinylpyrazole, vinylcarbazole, N-vinylpyrrolidone, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, vinylpyridine N-oxide, vinylpyridinium salt, vinylpiperidine, N-vinylcaprolactam, 2-vinylpyrazine, N-vinylpiperazine, 4-methyl-5-vinylthiazole, N-vinylpurine, vinylmorpholine and vinyloxazoline. At least one of the following.

[0056] According to the present invention, preferably, based on the total weight of the multiphase composite material, the content of the polypropylene (A) is 40 to 90 wt%, preferably 45 to 80 wt%, more preferably 50 to 78 wt%, and the content of the polyolefin elastomer (B) is 10 to 60 wt%, preferably 20 to 65 wt%, more preferably 22 to 50 wt%.

[0057] According to the present invention, the multiphase composite material can be prepared by blending polypropylene (A) graft-modified with an olefin-containing functional monomer and a polyolefin elastomer (B).

[0058] In the present invention, the polypropylene (A) graft-modified with an alkenyl-containing functional monomer comprises structural units derived from homo- or copolymerized polypropylene and structural units derived from an alkenyl-containing functional monomer.

[0059] The "structural unit" means that it is a part of the polypropylene grafted with an alkenyl functional monomer, and its form is not limited. Specifically, the "structural unit derived from homo- or copolymerized polypropylene" refers to a product formed from homo- or copolymerized polypropylene, which includes both "group" and "polymer" forms. The "structural unit derived from an alkenyl functional monomer" refers to a product formed from an alkenyl functional monomer, which includes both "group" and "monomer" forms, and also "polymer" forms. The "structural unit" can be a repeating unit or a non-repeating independent unit.

[0060] According to a preferred embodiment of the present invention, the homopolymer or copolymer polypropylene has at least one of the following characteristics: a comonomer content of 0 to 15 mol%, preferably 0 to 12 mol%, more preferably 0 to 8 mol%; a melt flow rate at 230°C and a load of 2.16 kg of 1 to 10 g / 10 min, preferably 2 to 5 g / 10 min; a melting temperature Tm of 110 to 180°C, more preferably 120 to 170°C; a weight average molecular weight of 20×10 4 ~50×10 4 g / mol; flexural modulus of 500 to 2000 MPa, preferably 700 to 1700 MPa; elongation at break ≥ 200%, preferably elongation at break ≥ 300%; tensile strength greater than 5 MPa, preferably 10 to 40 MPa.

[0061] According to a preferred embodiment of the present invention, the comonomer of the copolymerized polypropylene is selected from at least one C2-C8 α-olefin other than propylene; preferably, the comonomer of the copolymerized polypropylene is selected from at least one of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene; further preferably, the comonomer of the copolymerized polypropylene is ethylene and / or 1-butene; and the comonomer content is 0.1 to 15 mol%, preferably 0.1 to 10 mol%, and more preferably 0.1 to 8 mol%, based on the total molar amount of the monomers. The copolymerized polypropylene of the present invention is preferably a porous granular or powdered resin.

[0062] The homopolymer or copolymer polypropylene of the present invention can be any commercially available polypropylene powder suitable for the present invention, or can be produced by the polymerization process described in Chinese patents CN102453180B, CN101490096B, CN102816269B, CN102816270B, etc.

[0063] The concept of "polyolefin elastomer" in the present invention is well known to those skilled in the art and refers to a non-crosslinked, elastic polyolefin material formed by copolymerization of ethylene with propylene or other α-olefins (such as 1-butene, 1-hexene, 1-octene, etc.). It can be any commercially available powder or pellet of at least one of ethylene / α-olefin copolymer elastomers (POE or OBC) and their modifications, propylene / α-olefin copolymer elastomers (PBE) and their modifications, ethylene propylene diene monomer (EPR) and its modifications, and ethylene propylene diene monomer (EPDM) and its modifications suitable for the present invention. These include, but are not limited to, Dow Chemical's Engage series, ExxonMobile's Exact series, Exxelor series, Vistamaxx series, and Dow Chemical's Versify series. It can also be prepared by the methods described in CN101490096A, CN112724303A, CN112724286A, CN102417561A, CN103450403A, CN108384133A and other patents or documents.

[0064] According to the present invention, preferably, the polyolefin elastomer has at least one of the following characteristics: a melt flow rate of 0.5 to 25 g / 10 min, preferably 0.8 to 10 g / 10 mjn at 230°C and a load of 2.16 kg; a density of 0.85 to 0.905 g / cm 3 , preferably 0.86 to 0.89 g / cm 3; The melting point is greater than 45°C, preferably 50°C to 120°C; the flexural modulus is less than 50MPa, preferably less than 40MPa; the ratio of the intrinsic viscosity of the polyolefin elastomer to the intrinsic viscosity of the polypropylene in component A is 0.7 to 1.5, preferably 0.8 to 1.2.

[0065] The present invention also provides a method for preparing the multiphase composite material, comprising the following steps: blending polypropylene (A) graft-modified with an olefin-containing functional monomer with a polyolefin elastomer (B) to prepare the multiphase composite material;

[0066] Preferably, based on the total weight of the multiphase composite material, the amount of the polypropylene (A) graft-modified with the olefinic functional monomer is 40 to 90 wt%, preferably 45 to 80 wt%, more preferably 50 to 78 wt%, and the amount of the polyolefin elastomer (B) is 10 to 60 wt%, preferably 20 to 65 wt%, more preferably 22 to 50 wt%.

[0067] According to a preferred embodiment of the present invention, the preparation method comprises the following steps:

[0068] S1: in the presence of an inert gas, subjecting a reaction mixture comprising homopolymerized or copolymerized polypropylene and an olefinic functional monomer to a grafting reaction to obtain polypropylene graft-modified with the olefinic functional monomer;

[0069] S2: mixing the polypropylene graft-modified with the alkenyl functional monomer with a polyolefin elastomer and optional additives, and extruding and granulating the mixture to obtain the multiphase composite material.

[0070] Preferably, the grafting point is initiated by a free radical initiator and further grafting reaction is carried out. In this case, the reaction mixture also includes a free radical initiator.

[0071] Among them, the peroxide free radical initiator is preferably selected from at least one of dibenzoyl peroxide, diisopropyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, dodecyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, tert-butyl peroxy(2-ethylhexanoate) and dicyclohexyl peroxydicarbonate; the azo free radical initiator is preferably azobisisobutyronitrile and / or azobisisoheptonitrile.

[0072] More preferably, the grafting point is initiated by a peroxide-based free radical initiator and the grafting reaction is further carried out.

[0073] In addition, the grafting reaction of the present invention can also be carried out by the methods described in CN106543369A, CN104499281A, CN102108112A, CN109251270A, CN1884326A and CN101492517B.

[0074] Under the premise of meeting the above-mentioned product characteristics, the present invention has no particular limitation on the amount of each component used in the grafting reaction. Specifically, the mass ratio of the free radical initiator to the olefinic functional monomer is 0.01 to 10:100, preferably 0.5 to 5:100. The mass ratio of the olefinic functional monomer to the homo- or copolymerized polypropylene is 0.5 to 35:100, preferably 2 to 30:100, and more preferably 5 to 25:100.

[0075] The present invention has no particular limitation on the process conditions of the grafting reaction. Preferably, the grafting reaction is a solid phase grafting reaction. Specifically, the grafting reaction temperature is 30 to 130° C., preferably 60 to 120° C., and the grafting reaction time is 0.5 to 10 hours, preferably 1 to 5 hours.

[0076] In the present invention, the "reaction mixture" includes all materials added to the grafting reaction system. The materials can be added at once or at different stages of the reaction.

[0077] The reaction mixture of the present invention may further include a dispersant, which is preferably water or an aqueous solution of sodium chloride. The mass amount of the dispersant is preferably 50 to 300% of the mass of the polypropylene.

[0078] The reaction mixture of the present invention may further include an interfacial agent, which is an organic solvent that has a swelling effect on polyolefins, preferably at least one of the following organic solvents that have a swelling effect on polypropylene: ether solvents, ketone solvents, aromatic hydrocarbon solvents, and alkane solvents; more preferably at least one of the following organic solvents: chlorobenzene, polychlorinated benzenes, alkanes or cycloalkanes with C6 or higher, benzene, C1-C4 alkyl-substituted benzenes, C2-C6 aliphatic ethers, C3-C6 aliphatic ketones, and decalin; and even more preferably at least one of the following organic solvents: benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, diethyl ether, acetone, hexane, cyclohexane, decalin, and heptane. The weight content of the interfacial agent is preferably 1-30% of the weight of the polypropylene, and more preferably 10-25%.

[0079] The reaction mixture of the present invention may further include an organic solvent as a solvent for dissolving the solid free radical initiator. The organic solvent preferably includes at least one of C2-C5 alcohols, C2-C4 ethers, and C3-C5 ketones, more preferably includes at least one of C2-C4 alcohols, C2-C3 ethers, and C3-C5 ketones, and most preferably includes at least one of ethanol, diethyl ether, and acetone. The mass content of the organic solvent is preferably 1 to 35% of the mass of the polypropylene.

[0080] According to a preferred embodiment of the present invention, the preparation method comprises the following steps:

[0081] a. Place homopolymer or copolymer polypropylene in a closed reactor and replace with inert gas;

[0082] b. adding a free radical initiator and an olefin-functional monomer into the closed reactor and stirring to mix;

[0083] c. optionally adding an interfacial agent, and optionally causing the reaction system to swell;

[0084] d. optionally adding a dispersant, heating the reaction system to the grafting reaction temperature, and performing the grafting reaction;

[0085] e. After the reaction is completed, filtration is optionally performed (when an aqueous dispersant is used), and the polypropylene containing an olefin-functional monomer graft-modified is obtained after drying;

[0086] f. The polypropylene graft-modified with the alkenyl functional monomer is mixed with a polyolefin elastomer and an optional additive, and melt-extruded and granulated to obtain the multiphase composite material.

[0087] Specifically, the preparation method comprises the following steps:

[0088] a. Place homopolymer or copolymer polypropylene in a closed reactor and replace with inert gas;

[0089] b. adding a free radical initiator and an olefin-functional monomer into the closed reactor and stirring to mix;

[0090] c. adding 0 to 30 parts of an interfacial agent, and optionally allowing the reaction system to swell at 20 to 60 ° C for 0 to 24 hours;

[0091] d. Add 0 to 300 parts of dispersant, heat the system to the graft polymerization temperature of 30 to 130 ° C, and react for 0.5 to 10 hours;

[0092] e. After the reaction is completed, filtration is optionally performed (when an aqueous dispersant is used), and the polypropylene containing an olefin-functional monomer graft-modified is obtained after drying;

[0093] f. The polypropylene grafted with the alkenyl functional monomer is mixed with a polyolefin elastomer and an optional additive in proportion, and the mixture is pelletized by a twin-screw extruder at a melt temperature of 180°C to 230°C and a screw speed of 30 to 600 rpm to obtain the multiphase composite material.

[0094] According to another preferred embodiment of the present invention, the preparation method comprises the following steps:

[0095] a. Place homopolymer or copolymer polypropylene in a closed reactor and replace with inert gas;

[0096] b. mixing an organic solvent and a free radical initiator and adding the mixture to the closed reactor;

[0097] c. removing the organic solvent;

[0098] d. adding an olefin-functional monomer, optionally adding an interfacial agent, and optionally allowing the reaction system to swell;

[0099] e. optionally adding a dispersant, heating the reaction system to the grafting reaction temperature, and performing the grafting reaction;

[0100] f. After the reaction is completed, filtration is optionally performed (when an aqueous dispersant is used), and the polypropylene containing an olefin-functional monomer graft-modified is obtained after drying;

[0101] g. The polypropylene grafted with the alkenyl functional monomer is mixed with a polyolefin elastomer and optional additives in proportion, melt-extruded and granulated to obtain the multiphase composite material.

[0102] Specifically, the preparation method comprises the following steps:

[0103] a. Place homopolymer or copolymer polypropylene in a closed reactor and replace with inert gas;

[0104] b. mixing an organic solvent and a free radical initiator and adding the mixture to the closed reactor;

[0105] c. removing the organic solvent;

[0106] d. adding an olefin-containing functional monomer, adding 0 to 30 parts of an interfacial agent, and optionally allowing the reaction system to swell at 20 to 60 ° C for 0 to 24 hours;

[0107] e. Add 0 to 300 parts of dispersant, heat the system to the graft polymerization temperature of 30 to 130 ° C, and react for 0.5 to 10 hours;

[0108] f. After the reaction is completed, filtration is optionally performed (when an aqueous dispersant is used), and the polypropylene containing an olefin-functional monomer graft-modified is obtained after drying;

[0109] g. The polypropylene grafted with the alkenyl functional monomer is mixed with a polyolefin elastomer and an optional additive in proportion, and the mixture is pelletized by a twin-screw extruder at a melt temperature of 180°C to 230°C and a screw speed of 30 to 600 rpm to obtain the multiphase composite material.

[0110] According to the method of the present invention, if volatile components are present in the system after the reaction is completed, the method of the present invention preferably includes a devolatilization step. The devolatilization can be performed by any conventional method, including vacuum extraction at the end of the grafting process or the use of a stripping agent. Suitable stripping agents include, but are not limited to, inert gases.

[0111] As described above, the "polypropylene graft-modified with an alkenyl-functional monomer" of the present invention includes both the product (crude product) directly obtained by grafting polypropylene and an alkenyl-functional monomer, and the pure graft-modified polypropylene obtained by further purification of the product. Therefore, the preparation method of the present invention may optionally include a step of purifying the crude product. The purification may be performed by various conventional methods in the art, such as extraction.

[0112] The present invention does not specifically limit the grafting efficiency of the grafting reaction, but a higher grafting efficiency is more conducive to obtaining a polypropylene material grafted with an olefinic-functional monomer having desired properties through a single-step grafting reaction. Therefore, the grafting efficiency of the grafting reaction is preferably controlled to be 20-100%, more preferably 25-80%. The concept of grafting efficiency is well known to those skilled in the art and refers to the amount of grafted olefinic-functional monomer divided by the total amount of olefinic-functional monomer fed into the reaction.

[0113] The inert gas of the present invention can be any of the inert gases commonly used in the art, including but not limited to nitrogen and argon.

[0114] In the method of the present invention, the graft-modified polypropylene, the polyolefin elastomer, and any optional additives may be mixed mechanically, preferably by twin-screw mechanical blending. The additives may be, for example, one or more of an antioxidant, a stabilizer, and a processing aid. The types and amounts of the additives used are conventional and known to those skilled in the art.

[0115] The multi-phase composite material of the present invention can be applied in the field of cables, for example, as an insulation material.

[0116] The present invention will be further described below with reference to the examples, but the scope of the present invention is not limited to these examples.

[0117] Test Method

[0118] 1. Determination of comonomer content in polypropylene:

[0119] The comonomer content was determined by quantitative Fourier transform infrared (FTIR) spectroscopy. The correlation of the comonomer content determined was calibrated by quantitative nuclear magnetic resonance (NMR) spectroscopy. 13 The calibration method of the results obtained by C-NMR spectrum was carried out according to the conventional method in the art.

[0120] 2. Determination of xylene soluble content (XS)

[0121] The test was carried out according to the method specified in GB / T 24282-2009.

[0122] 3. Viscosity ratio of polyolefin elastomer to homopolymer or copolymer polypropylene

[0123] The intrinsic viscosity of the polyolefin elastomer and the copolymerized polypropylene was measured using a Viscotek Model 430 viscometer from Malvern, UK, and the ratio of the two was calculated. The solvent was decalin, the dissolution temperature was 150°C, the dissolution time was 1 hour, and the mass concentration was 0.1 g / dL.

[0124] 4. Polypropylene weight average molecular weight (M w ) determination:

[0125] High-temperature GPC was used on a Polymer Laboratory PL-GPC 220 gel permeation chromatograph. The sample was dissolved in 1,2,4-trichlorobenzene at a concentration of 1.0 mg / ml. The test temperature was 150°C, and the flow rate was 1.0 ml / min. A standard curve was constructed using the molecular weight of polystyrene as an internal reference. The molecular weight and molecular weight distribution of the sample were calculated based on the elution time.

[0126] 5. Determination of melt flow rate MFR:

[0127] The melt index was determined using a CEAST 7026 melt indexer at 230°C and a load of 2.16 kg, according to the method specified in GB / T 3682-2018.

[0128] 6. Determination of melting temperature Tm:

[0129] Differential scanning calorimetry was used to analyze the melting and crystallization processes of the material. Specifically, under nitrogen protection, 5-10 mg of sample was measured from 20°C to 200°C using a three-stage temperature ramp. The changes in heat flow reflect the melting and crystallization processes of the material, and the melting temperature (Tm) was calculated.

[0130] 7. Determination of density of polyolefin elastomers:

[0131] The determination was carried out according to the method specified in GB / T 1033.2-2010.

[0132] 8. Determination of grafting efficiency GE and parameter M1:

[0133] The composite material product was crushed into powder, 2-4 g was taken and placed in a Soxhlet extractor, and extracted with an organic solvent (ethyl acetate for aromatic olefin monomers and acrylate monomers; acetone for silane monomers) for 24 hours to remove unreacted monomers and their homopolymers to obtain a pure grafted product, which was dried and weighed, and the parameters M1 and grafting efficiency GE were calculated.

[0134] The parameter M1 represents the content of structural units derived from alkenyl-containing functional monomers and in a grafted state in the composite material, and is calculated as follows:

[0135]

[0136]

[0137] In the above formula, w0 is the total mass of the polypropylene base material (i.e., the homopolymer or copolymer polypropylene) and the polyolefin elastomer; w1 is the mass of the product before extraction; w2 is the mass of the product after extraction; and w3 is the mass of the added olefin-containing functional monomer.

[0138] 9. Determination of DC volume resistivity:

[0139] The determination was carried out according to the method specified in GB / T 1410-2006.

[0140] 10. Determination of breakdown field strength:

[0141] The determination was carried out according to the method specified in GB / T 1408-2006.

[0142] 11. Determination of tensile strength:

[0143] The determination was carried out according to the method specified in GB / T 1040.2-2006.

[0144] 12. Determination of flexural modulus:

[0145] The determination was carried out according to the method specified in GB / T 9341-2008.

[0146] 13. Determination of elongation at break:

[0147] The determination was carried out according to the method specified in GB / T 1040-2006.

[0148] 14. Determination of dielectric constant:

[0149] The determination was carried out according to the method specified in GB / T 1409-2006.

[0150] 15. Characterization of rubber phase

[0151] During twin-screw extrusion, one or two 5-10 cm long composite material strips were collected. The strips were soaked in liquid nitrogen for 15 minutes until they broke. The cross-sections were then soaked in xylene at room temperature for 24 hours, then ultrasonically soaked in clean water for 15 minutes. Finally, the cross-sections were rinsed with alcohol and air-dried. The cross-sections were then gold-sprayed and characterized using a scanning electron microscope.

[0152] 16. Characterization of the grafted phase and calculation of D50

[0153] Composite material specimens were soaked in liquid nitrogen for 15 minutes before being fractured. The cross-sections were then gold-sprayed and characterized using a scanning electron microscope to obtain microscopic morphology photographs. Analysis software was used to measure the diameter of 200 dispersed phases from each sample, and the D50 (D50) was calculated using data processing software. D50 represents the median particle size, which is the particle size at which the cumulative particle size distribution of a sample reaches 50%.

[0154] 17. Characterization of three-phase structure

[0155] The composite material specimens were cooled to -50℃ by liquid nitrogen and sliced. The microstructure of the composite material was characterized by a Dimension fast scanning atomic force microscope produced by Bruker Company, Germany.

[0156] Example

[0157] The raw materials and their properties used in the examples are described in Table A, Table B and Table C.

[0158] Table A

[0159] name describe PP 1* Made by referring to the method described in CN110305400A PP 2* Reference CN102453180A described method homemade PP 3* Reference CN102816269A described method homemade PO 1* Reference CN101490096A described method homemade PO 2* Reference CN101490096A described method homemade PO 3* Reference CN112724303A described method homemade Benzoyl peroxide J&K Chemicals Lauroyl peroxide J&K Chemicals tert-Butyl peroxy(2-ethylhexanoate) Adamas Reagents Co., Ltd. (adamas-beta) Styrene J&K Chemicals Vinyltriethoxysilane J&K Chemicals Methyl methacrylate J&K Chemicals Polystyrene GPPS-123 Shanghai Secco Petrochemical Co., Ltd.

[0160] *PP 1: homopolypropylene used in Example 1 and Comparative Examples 1, 3, and 5.

[0161] *PP 2: copolymerized polypropylene used in Examples 2, 3 and Comparative Example 4.

[0162] *PP 3: copolymerized polypropylene used in Example 4.

[0163] *PO 1: polyolefin elastomer used in Examples 1 and 2 and Comparative Examples 3, 4 and 5.

[0164] *PO 2: polyolefin elastomer used in Example 3.

[0165] *PO 3: polyolefin elastomer used in Example 4.

[0166] Table B

[0167]

[0168]

[0169] Table C

[0170]

[0171] Example 1

[0172] Weigh 2.0 kg of PP1 powder, sieved to remove fines smaller than 40 mesh, and add it to a 10 L reactor with mechanical stirring. The reaction system is sealed and deoxygenated by nitrogen exchange. Add 3 g of tert-butyl peroxy(2-ethylhexanoate) and 200 g of styrene, stir and mix for 30 minutes. Add 2 kg of dispersant water, allow to swell at 50°C for 2 hours, then heat to 90°C and react for 4 hours. After the reaction is complete, cool the mixture, filter out the dispersant water, and vacuum dry at 70°C for 10 hours to obtain polypropylene-g-styrene powder.

[0173] 1.2 kg of polypropylene-g-styrene powder and PO1 were weighed in a 60:40 mass ratio, and 3000 ppm of antioxidant 1010 / 168 (mass ratio 1:1) was added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 400 rpm to obtain composite material C1. The performance parameters of the resulting product are shown in Table 1.

[0174] Figure 1 This is an atomic force microscope image (modulus map) of the material product in Example 1. The bright white area in the image represents the styrene grafted phase, the black area represents the rubber phase, and the other areas represent the continuous phase.

[0175] Figure 2 This is a microstructure photograph of the material product in Example 1 under a 10,000x electron microscope, in which the spherical dispersed phase is the styrene grafted phase. It can be seen that the styrene grafted phase has a small particle size and a regular morphology.

[0176] Example 2

[0177] Weigh 2.0 kg of PP2 powder, sieved to remove fines smaller than 40 mesh, and add it to a 10 L reactor with mechanical stirring. The reaction system is sealed and deoxygenated by nitrogen exchange. Add 1.6 g of dibenzoyl peroxide and 100 g of styrene, stir and mix for 30 minutes, allow to swell at 40°C for 2 hours, then heat to 100°C and react for 3 hours. After the reaction is complete, cool and vacuum dry at 70°C for 10 hours to obtain polypropylene-g-styrene powder.

[0178] 1.2 kg of polypropylene-g-styrene powder and PO1 were weighed in a 65:35 mass ratio. 3000 ppm of antioxidant 1035 was added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 450 rpm to produce composite material C2. The performance parameters of the resulting product are shown in Table 1. Figure 3 This is a microscopic photograph of the material product in Example 2 under a 10,000x electron microscope, in which the spherical dispersed phase is the styrene grafted phase. It can be seen that the styrene grafted phase has a small particle size and a regular morphology.

[0179] Example 3

[0180] Weigh 2.0 kg of PP2 powder, sieved to remove fines smaller than 40 mesh, and add it to a 10 L reactor with mechanical stirring. The reaction system is sealed and deoxygenated by nitrogen exchange. Add 2.2 g of dibenzoyl peroxide and 100 g of methyl methacrylate, stir for 20 minutes, heat to 95°C, and react for 5 hours. After the reaction is complete, cool the mixture and vacuum dry it at 70°C for 10 hours to obtain polypropylene-g-methyl methacrylate powder.

[0181] 1.2 kg of polypropylene-g-methyl methacrylate powder and PO2 were weighed in a 50:50 mass ratio. 3000 ppm of antioxidant 1035 was added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature profile of 200-210-220-230-230-230-230-220-220-210°C and a screw speed of 350 rpm to produce composite material C3. The performance parameters of the resulting product are shown in Table 1. Figure 4 This is a microscopic photograph of the material product in Example 3 under a 10,000x electron microscope, showing the spherical dispersed phase, namely the methyl methacrylate grafted phase. It can be seen that the methyl methacrylate grafted phase has a small particle size and a regular morphology.

[0182] Example 4

[0183] Weigh 2.0 kg of PP3 powder, sieved to remove fines smaller than 40 mesh, and add it to a 10 L reactor with mechanical stirring. The reaction system is sealed and deoxygenated with nitrogen. Mix 5 g of lauroyl peroxide, 100 g of vinyltriethoxysilane, and 100 ml of xylene until uniform. Add the mixture to the reactor and stir for 20 minutes. Heat the mixture to 105°C and react for 4 hours. After the reaction is complete, cool the mixture and vacuum dry it at 70°C for 10 hours to obtain polypropylene-g-vinyltriethoxysilane powder.

[0184] 1.2 kg of polypropylene-g-vinyltriethoxysilane powder and PO3 were weighed in a 70:30 mass ratio. 2000 ppm of antioxidant 1024 was added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 200-210-220-230-230-230-230-220-220-210°C and a screw speed of 400 rpm to obtain composite material C4. The performance parameters of the resulting product were tested, and the results are shown in Table 1. Figure 5 This is a microstructure photograph of the material product in Example 4 under a 10,000x electron microscope, in which the spherical dispersed phase is the vinyltriethoxysilane grafted phase. It can be seen that the vinyltriethoxysilane grafted phase has a small particle size and a regular morphology.

[0185] Comparative Example 1

[0186] Weigh 2.0 kg of PP1 powder, sieved to remove fines smaller than 40 mesh, and add it to a 10 L reactor with mechanical stirring. The reaction system is sealed and nitrogen is purged to remove oxygen. Add 2 g of dibenzoyl peroxide and 100 g of styrene, stir and mix for 60 minutes, allow to swell at 40°C for 4 hours, then heat to 95°C and react for 4 hours. After the reaction is complete, purge with nitrogen to cool the mixture to obtain polypropylene-g-styrene powder.

[0187] 1.2 kg of polypropylene-g-styrene powder was weighed, 3000 ppm of antioxidant 1010 / 168 (mass ratio 1:1) was added, and the mixture was mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 400 rpm to obtain product D1. The performance parameters of the resulting product were tested, and the results are shown in Table 1.

[0188] Comparative Example 2

[0189] The polypropylene powder with the following characteristics was selected: the content of ethylene comonomer was 20.2 mol%, the content of xylene soluble matter was 44.2 wt%, and the weight average molecular weight was 35.3×10 4 g / mol, an MFR of 1.55 g / 10 min at 230°C and a load of 2.16 kg, and a Tm of 143.6°C. 1.2 kg of the aforementioned polypropylene powder was weighed, 3000 ppm of antioxidant 1010 / 168 (mass ratio 1:1) was added, and the mixture was uniformly mixed in a high-speed mixer. The product was then pelletized using a twin-screw extruder at zone temperatures of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 400 rpm to obtain product D2. The performance parameters of the resulting product were tested, and the results are shown in Table 1.

[0190] Comparative Example 3

[0191] 1.2 kg of PP1 powder and PO1 powder (60:40 by mass) were weighed, and 3000 ppm of antioxidant 1010 / 168 (1:1 by mass) was added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 400 rpm to produce composite material D3. The performance parameters of the resulting product are shown in Table 1.

[0192] Figure 6 This is a microstructure photograph of the product in Comparative Example 3 under a 10,000x electron microscope. Figure 7 This is a microstructure photo of the product in Comparative Example 3 after etching under a 10,000x electron microscope. The black part is the rubber phase. Figure 6 and Figure 7 It can be seen that the ungrafted product includes a rubber phase but does not contain a grafted phase. The grafted product of the present invention has a three-phase structure including both a rubber phase and a grafted phase.

[0193] Comparative Example 4

[0194] Weigh 2.0 kg of PP2 powder, sieved to remove fines smaller than 40 mesh, and add it to a 10-liter reactor with mechanical stirring. The reaction system is sealed and deoxygenated by nitrogen exchange. Then, 10 g of benzoyl peroxide and 566.7 g of styrene are added and stirred for 30 minutes. Then, 2 L of deionized water is added and the mixture is allowed to swell at 40°C for 2 hours. The mixture is then heated to 90°C and allowed to react for 6 hours. After the reaction is complete, the mixture is cooled and vacuum-dried at 70°C for 10 hours to obtain polypropylene-g-styrene powder.

[0195] 1.2 kg of polypropylene-g-styrene powder and PO1 were weighed in a 60:40 mass ratio. 3000 ppm of antioxidant 1035 was added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 450 rpm to obtain composite material D4. The performance parameters of the resulting product were tested, and the results are shown in Table 1.

[0196] Figure 8 This is a microstructure photograph of the product in Comparative Example 4 under a 10,000x electron microscope.

[0197] Comparative Example 5

[0198] 1.2 kg of PP1, PO1, and polystyrene GPPS-123 were weighed in a mass ratio of 60:35:5, and 3000 ppm of antioxidant 1010 / 168 (mass ratio 1:1) were added and mixed thoroughly in a high-speed mixer. The mixture was then pelletized using a twin-screw extruder at a temperature range of 190-200-210-220-220-220-220-220-210-200°C and a screw speed of 400 rpm to produce composite material D5. The performance parameters of the resulting product were tested, and the results are shown in Table 1.

[0199] Figure 9 This is a microstructure photograph of the product in Comparative Example 5 under a 10,000x electron microscope. Due to poor compatibility, the dispersed phase size is uneven, and there is an obvious large-sized dispersed phase.

[0200]

[0201] Comparing the data of Example 1 and Comparative Example 1, it can be seen that the bending modulus of the polypropylene-g-styrene material product obtained by using T30S powder as the base powder is too high, the mechanical properties of the material are poor, and it cannot meet the processing and use requirements of the insulation material.

[0202] Comparing the data of Example 1 and Comparative Example 2, it can be seen that the mechanical properties of the product obtained by the present invention are not inferior to those of the polypropylene prepared by the in-vessel alloy direct method, while the electrical properties are more advantageous.

[0203] Comparing the data of Example 1 and Comparative Example 3, it can be seen that the mechanical properties of the multiphase composite material are almost the same as those of the material without the grafted phase, while the breakdown field strength and DC volume resistivity are improved, indicating that the multiphase composite material of the present invention has good electrical properties.

[0204] Comparing the data of Example 1 and Comparative Example 4, it can be seen that if the graft phase D50 is too large, the breakdown field strength and volume resistivity of the obtained multiphase composite material product will decrease, affecting the electrical properties of the material.

[0205] Comparing the data of Example 1 and Comparative Example 5, it can be seen that the dispersed phase size of the olefinic functional monomer is too large by blending the olefinic functional monomer polymer, resulting in a significant decrease in the breakdown field strength and volume resistivity of the material, which greatly affects the electrical properties of the material.

[0206] In summary, it can be seen from the data in Table 1 that the multiphase composite material obtained in the present invention not only has excellent electrical insulation properties, but also has good mechanical properties.

[0207] In addition, it can be seen from the dielectric constant data that the material of the present invention meets the necessary conditions for insulation.

[0208] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0209] The endpoints of the ranges and any values disclosed herein 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 endpoints of each range, the endpoints of each range and 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 considered to be specifically disclosed herein.

Claims

1. A multiphase composite material comprising polypropylene (A) graft-modified with an olefin-containing functional monomer and a polyolefin elastomer (B); wherein: The multiphase composite material has a xylene soluble content of 15 to 75 wt % based on the total weight of the multiphase composite material; the content of structural units derived from the alkenyl-functional monomer in a grafted state in the multiphase composite material is 0.4 to 8 wt %; the multiphase composite material has a flexural modulus of 200 to 1000 MPa; and the D50 of the grafted phase derived from the alkenyl-functional monomer is less than 300 nm; The alkenyl-functional monomer is an aromatic olefin monomer, and the aromatic olefin monomer is selected from at least one of styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, mono-substituted or poly-substituted styrene, mono-substituted or poly-substituted 1-vinylnaphthalene and mono-substituted or poly-substituted 2-vinylnaphthalene; and / or The alkenyl-containing functional monomer is an alkenyl-containing silane monomer, and the alkenyl-containing silane monomer is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriisopropoxysilane, vinyltri-tert-butoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, ethylvinyldiethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, allyltriisopropoxysilane, vinyltris(β-methoxyethoxy)silane, allyltris(β-methoxyethoxy)silane, allyltri-tert-butoxysilane, allyltriacetoxysilane, methylallyldimethoxysilane and ethylallyldiethoxysilane; and / or The alkenyl functional monomer is an acrylate monomer and an optional acrylic acid monomer.

2. The multiphase composite material according to claim 1, wherein The aromatic olefin monomer is α-methylstyrene.

3. The multiphase composite material according to claim 1, wherein The aromatic olefin monomer is monosubstituted or polysubstituted α-methylstyrene.

4. The multiphase composite material according to claim 1, wherein The xylene soluble content of the multiphase composite material is 20-60 wt %.

5. The multiphase composite material according to claim 4, wherein The xylene soluble content of the multiphase composite material is 25-55 wt %.

6. The multiphase composite material according to claim 1, wherein The content of the structural units derived from the alkenyl-containing functional monomer in the grafted state in the multiphase composite material is 1 to 5 wt %.

7. The multiphase composite material according to claim 1, wherein The D50 of the grafted phase is 10-250 nm; and the flexural modulus of the multiphase composite material is 200-700 MPa.

8. The multiphase composite material according to claim 7, wherein: The D50 of the grafted phase is 50-220 nm.

9. The multiphase composite material according to claim 7, wherein: The multiphase composite material has a flexural modulus of 250-600 MPa.

10. The multiphase composite material according to claim 1, wherein The multiphase composite material has at least one of the following characteristics: a melt flow rate of 0.5 to 15 g / 10 min at 230° C. and a load of 2.16 kg; an elongation at break of ≥200%; and a tensile strength greater than 5 MPa.

11. The multiphase composite material according to claim 10, wherein: The melt flow rate at 230 ℃ and 2.16 kg load is 1~10 g / 10min.

12. The multiphase composite material according to claim 11, wherein The melt flow rate at 230 ℃ and 2.16 kg load is 1.5~6 g / 10min.

13. The multiphase composite material according to claim 10, wherein: Elongation at break ≥300%.

14. The multiphase composite material according to claim 10, wherein: The tensile strength is 10~25 MPa.

15. The multiphase composite material according to claim 1, wherein: The multiphase composite material has at least one of the following characteristics: -The maximum operating temperature of the multiphase composite material is ≥90°C; - the multiphase composite material has a breakdown field strength Eg ≥ 290 kV / mm at 110°C; - DC volume resistivity ρ of the multiphase composite material at 110 °C and 40 kV / mm field strength vg ≥1.0×10 13 Ω•m; The multiphase composite material has a dielectric constant greater than 2.0 at 110°C and 50 Hz.

16. The multiphase composite material according to claim 15, wherein: The maximum operating temperature of the multiphase composite material is 100-160°C.

17. The multiphase composite material according to claim 16, wherein: The maximum operating temperature of the multiphase composite material is 110-140°C.

18. The multiphase composite material according to claim 15, wherein The multiphase composite material has a breakdown field strength Eg of 300-800 kV / mm at 110°C.

19. The multiphase composite material according to claim 18, wherein The multiphase composite material has a breakdown field strength Eg of 305-750 kV / mm at 110°C.

20. The multiphase composite material according to claim 15, wherein The DC volume resistivity ρ of the multiphase composite material at 110 °C and 40 kV / mm field strength vg 1.5×10 13 Ω•m~1.0×10 20 Ω•m.

21. The multiphase composite material according to claim 15, wherein The dielectric constant of the multiphase composite material at 110° C. and 50 Hz is 2.1-2.

5.

22. The multiphase composite material according to claim 1, wherein The substituted group is selected from at least one of halogen, hydroxyl, amino, phosphate, sulfonic acid, C1-C8 straight-chain alkyl, C3-C8 branched-chain alkyl or cycloalkyl, C1-C6 straight-chain alkoxy, C3-C8 branched-chain alkoxy or cyclic alkoxy, C1-C8 straight-chain ester, C3-C8 branched-chain ester or cyclic ester, C1-C8 straight-chain amine, and C3-C8 branched-chain amine or cyclic amine.

23. The multiphase composite material according to claim 22, wherein: The aromatic olefin monomer is at least one selected from styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene and 4-methylstyrene.

24. The multiphase composite material according to claim 1, wherein The acrylic acid ester monomer is selected from at least one of methyl (meth)acrylate, sec-butyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, dodecyl (meth)acrylate, coconut (meth)acrylate, octadecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate and glycidyl (meth)acrylate.

25. The multiphase composite material according to claim 1, wherein The acrylic monomer is selected from at least one of acrylic acid, methacrylic acid and 2-ethylacrylic acid.

26. The multiphase composite material according to claim 1, wherein The molar ratio of the structural unit derived from the acrylate monomer to the structural unit derived from the acrylic acid monomer is 1:0-2.

27. The multiphase composite material according to claim 26, wherein The molar ratio of the structural unit derived from the acrylate monomer to the structural unit derived from the acrylic acid monomer is 1:0.125~1.

28. The multiphase composite material according to any one of claims 1 to 23, wherein: Based on the total weight of the multiphase composite material, the content of the polypropylene (A) graft-modified with the olefinic functional monomer is 40-90 wt%, and the content of the polyolefin elastomer (B) is 10-60 wt%.

29. The multiphase composite material according to claim 28, wherein Based on the total weight of the multiphase composite material, the content of the polypropylene (A) graft-modified with the olefinic functional monomer is 45-80 wt%, and the content of the polyolefin elastomer (B) is 20-65 wt%.

30. The multiphase composite material according to claim 29, wherein Based on the total weight of the multiphase composite material, the content of the polypropylene (A) graft-modified with the olefinic functional monomer is 50-78 wt%, and the content of the polyolefin elastomer (B) is 22-50 wt%.

31. The multiphase composite material according to claim 28, wherein The multiphase composite material is prepared by blending polypropylene (A) modified by grafting of olefin-containing functional monomers and polyolefin elastomer (B).

32. The multiphase composite material of claim 1, wherein: The polypropylene (A) graft-modified with an alkenyl-containing functional monomer comprises a structural unit derived from homo- or copolymerized polypropylene and a structural unit derived from an alkenyl-containing functional monomer.

33. The multiphase composite material according to claim 32, wherein The homopolymer or copolymer polypropylene has at least one of the following characteristics: a comonomer content of 0 to 15 mol%; a melt flow rate of 1 to 10 g / 10 min at 230°C and a load of 2.16 kg; a melting temperature Tm of 110 to 180°C; a weight average molecular weight of 20×10 4 ~50×10 4 g / mol; flexural modulus is 500~2000 MPa; elongation at break is ≥200%; tensile strength is greater than 5 MPa.

34. The multiphase composite material according to claim 33, wherein The comonomer content is 0~12 mol%.

35. The multiphase composite material according to claim 34, wherein The comonomer content is 0~8 mol%.

36. The multiphase composite material of claim 33, wherein: The melt flow rate at 230 ℃ and 2.16 kg load is 2~5 g / 10 min.

37. The multiphase composite material of claim 33, wherein: The melting temperature Tm is 120~170 ℃.

38. The multiphase composite material of claim 33, wherein: The flexural modulus is 700~1700 MPa.

39. The multiphase composite material of claim 33, wherein: Elongation at break ≥300%.

40. The multiphase composite material of claim 33, wherein: The tensile strength is 10~40 MPa.

41. The multiphase composite material of claim 32, wherein: The comonomer of the copolymerized polypropylene is selected from at least one C2-C8 α-olefin except propylene; the comonomer content is 0.1-15 mol% based on the total molar amount of the monomers.

42. The multiphase composite material according to claim 41, wherein The comonomer of the copolymerized polypropylene is at least one selected from the group consisting of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene.

43. The multiphase composite material of claim 42, wherein: The comonomer of the copolymerized polypropylene is ethylene and / or 1-butene.

44. The multiphase composite material of claim 41, wherein The comonomer content is 0.1-12 mol% based on the total molar amount of the monomers.

45. The multiphase composite material of claim 44, wherein: The comonomer content is 0.1-8 mol% based on the total molar amount of the monomers.

46. The multiphase composite material of claim 1, wherein: The polyolefin elastomer is selected from at least one of ethylene / α-olefin copolymer elastomer, propylene / α-olefin copolymer elastomer, EPDM rubber and EPDM rubber.

47. The multiphase composite material of claim 46, wherein: The polyolefin elastomer has at least one of the following characteristics: a melt flow rate of 0.5 to 25 g / 10 min at 230° C. and a load of 2.16 kg; a density of 0.85 to 0.905 g / cm 3 ; Melting point greater than 45 ℃; Flexural modulus less than 50 MPa; The ratio of the intrinsic viscosity of the polyolefin elastomer to the intrinsic viscosity of the polypropylene in component A is 0.7~1.

5.

48. The multiphase composite material of claim 47, wherein The melt flow rate at 230 °C and 2.16 kg load is 0.8~10 g / 10min; the density is 0.86~0.89 g / cm 3 ; The melting point is 50 ℃ ~ 120 ℃; The flexural modulus is less than 40MPa; The ratio of the intrinsic viscosity of the polyolefin elastomer to the intrinsic viscosity of the polypropylene in component A is 0.8 ~ 1.

2.

49. A method for preparing the multiphase composite material according to any one of claims 1 to 48, comprising the following steps: The multiphase composite material is prepared by blending polypropylene (A) graft-modified with an olefin-containing functional monomer and a polyolefin elastomer (B).

50. The preparation method according to claim 49, wherein Based on the total weight of the multiphase composite material, the amount of the polypropylene (A) graft-modified with the olefin-containing functional monomer is 40-90 wt%, and the amount of the polyolefin elastomer (B) is 10-60 wt%.

51. The preparation method according to claim 50, wherein Based on the total weight of the multiphase composite material, the amount of the polypropylene (A) graft-modified with the olefin-containing functional monomer is 45-80 wt%, and the amount of the polyolefin elastomer (B) is 20-65 wt%.

52. The preparation method according to claim 51, wherein Based on the total weight of the multiphase composite material, the amount of the polypropylene (A) graft-modified with the olefin-containing functional monomer is 50-78 wt%, and the amount of the polyolefin elastomer (B) is 22-50 wt%.

53. The preparation method according to claim 49, wherein The preparation method comprises the following steps: S1: in the presence of an inert gas, subjecting a reaction mixture comprising homopolymerized or copolymerized polypropylene and an olefinic functional monomer to a graft reaction to obtain polypropylene graft-modified with the olefinic functional monomer; S2: mixing the polypropylene graft-modified with the alkenyl functional monomer with a polyolefin elastomer and optional additives, and extruding and granulating the mixture to obtain the multiphase composite material.

54. The preparation method according to claim 53, wherein The reaction mixture includes a free radical initiator; the free radical initiator is selected from peroxide free radical initiators and / or azo free radical initiators.

55. The preparation method according to claim 54, wherein The peroxide free radical initiator is selected from at least one of dibenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, dodecyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, tert-butyl peroxy(2-ethylhexanoate) and dicyclohexyl peroxydicarbonate.

56. The preparation method according to claim 54, wherein The azo free radical initiator is azobisisobutyronitrile and / or azobisisoheptanenitrile.

57. The preparation method according to claim 54, wherein The mass ratio of the free radical initiator to the olefinic functional monomer is 0.01 to 10:

100.

58. The preparation method according to claim 57, wherein The mass ratio of the free radical initiator to the olefinic functional monomer is 0.5 to 5:

100.

59. The preparation method according to claim 53, wherein The mass ratio of the alkenyl-containing functional monomer to the homopolymer or copolymer polypropylene is 0.5-35:

100.

60. The preparation method according to claim 59, wherein The mass ratio of the alkenyl-containing functional monomer to the homopolymer or copolymer polypropylene is 2 to 30:

100.

61. The preparation method according to claim 60, wherein The mass ratio of the alkenyl-containing functional monomer to the homopolymer or copolymer polypropylene is 5 to 25:

100.

62. The preparation method according to claim 53, wherein The grafting reaction temperature is 30-130°C and the time is 0.5-10 hours.

63. The preparation method according to claim 62, wherein The grafting reaction temperature is 60-120°C and the time is 1-5 hours.

64. The preparation method according to claim 53, wherein The reaction mixture further comprises at least one of the following components: a dispersant, an interface agent, and an organic solvent. The mass content of the dispersant is 50-300% of the mass of the homo- or copolymerized polypropylene, the mass content of the interface agent is 1-30% of the mass of the homo- or copolymerized polypropylene, and the mass content of the organic solvent is 1-35% of the mass of the homo- or copolymerized polypropylene.

65. The preparation method according to claim 64, wherein The preparation method comprises the following steps: a. Place homopolymer or copolymer polypropylene in a closed reactor and replace with inert gas; b. adding a free radical initiator and an olefin-functional monomer into the closed reactor and stirring to mix; c. optionally adding an interfacial agent and optionally allowing the reaction system to swell; d. optionally adding a dispersant, heating the reaction system to a grafting reaction temperature, and performing a grafting reaction; e. After the reaction is completed, optionally filtering and drying to obtain polypropylene grafted with an olefin-functional monomer; f. Mixing the polypropylene graft-modified with the alkenyl functional monomer with a polyolefin elastomer and optional additives, and melt-extruding and granulating to obtain the multiphase composite material.

66. The preparation method according to claim 64, wherein The preparation method comprises the following steps: a. Place homopolymer or copolymer polypropylene in a closed reactor and replace with inert gas; b. mixing an organic solvent and a free radical initiator and adding the mixture to the closed reactor; c. removing the organic solvent; d. adding an ethylenic functional monomer, optionally adding an interfacial agent, and optionally allowing the reaction system to swell; e. optionally adding a dispersant, heating the reaction system to a grafting reaction temperature, and performing a grafting reaction; f. After the reaction is completed, optionally filtering and drying to obtain polypropylene grafted with an olefin-functional monomer; g. The polypropylene grafted with the alkenyl functional monomer is mixed with a polyolefin elastomer and optional additives in proportion, and melt-extruded to form pellets to obtain the multiphase composite material.

67. Use of the multiphase composite material according to any one of claims 1 to 48.

68. The use according to claim 67, wherein The multiphase composite material is applied in the field of cables.

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