Propylene-butene copolymer, method for preparing the same, and its use

Abstract

A propylene-butene copolymer is disclosed. The copolymer contains 90 to 99 mol% propylene structural units and 1 to 10 mol% butene structural units, based on the total amount of structural units of the copolymer. The xylene solubles content of the copolymer is 4 wt% or less, preferably 3 wt% or less. The propylene-butene copolymer is substantially free of fractions having a molecular weight of less than 1,000. The copolymer has a melt flow index of 20 g / 10 min or more when measured at 230°C under a load of 2.16 kg. The propylene-butene copolymer of the present invention has the advantages of a high melt flow index and low xylene solubles, and is free of phthalate ester plasticizers, making it useful for applications in fields such as food, medicine, and health services.

Description

Detailed description of the invention

[0001] [Cross-reference of related applications] This application claims priority and interest to CN202011104743.5 and CN202011103642.6, filed on 15 October 2020, which are incorporated herein by reference in their entirety for all purposes.

[0002] [Technical Field] The present invention belongs to the field of olefin polymerization, and more particularly to propylene-butene copolymers, methods for preparing propylene-butene copolymers, and applications of propylene-butene copolymers to food and / or medical and healthcare products.

[0003] [Background technology] Polypropylene (PP) is a colorless, transparent thermoplastic resin with the advantages of low relative density, ease of processing, high impact strength, corrosion resistance, good electrical insulation, and low cost. It is one of the fastest-growing materials among general-purpose plastics and is widely used in the chemical industry, construction, household electrical appliances, agriculture, the automotive industry, and other fields. Currently, new PP products are mainly concentrated in copolymer products. Propylene copolymerization includes copolymerization with monomers such as ethylene, butene, and long-chain α-olefins. The introduction of novel monomers into the molecular chain will clearly result in changes to the properties of polypropylene and an expansion of its application fields. Therefore, this has been a new direction in recent polypropylene development. Compared with conventional homopolymer PP, new PP copolymerized with propylene and butene has the advantages of high transparency, good gloss, high impact resistance, and low heat seal temperature. These can be widely used in the fields of packaging materials, medical devices, toys, household electrical appliances, automobiles, and other high-end daily necessities and are improved products of conventional homopolypropylene.

[0004] Currently, most commercialized propylene-butene copolymers are products with a low melt flow index and a high content of xylene solubles, and have low market competitiveness. Therefore, propylene-butene copolymers having both a high melt flow index and a low content of xylene solubles will have higher product added value and a broader market outlook due to their excellent processability and low content of leachates.

[0005] Regarding propylene-butene copolymers, from the perspective of environmental protection, it should be noted to (1) avoid the inclusion of substances harmful to health such as plasticizers, (2) reduce as much as possible small molecules that cause leaching or VOCs, and (3) reduce the content of extracts as much as possible, so as to avoid restrictions on applications in fields such as food packaging materials.

[0006] 〔Summary of the Invention〕 The object of the present invention is to provide a propylene-butene copolymer, a method for preparing the same, and its use. The copolymer has both a high melt flow index and a low content of xylene solubles, and thus can be advantageously used in fields such as food, pharmaceuticals, and healthcare.

[0007] A further object of the present invention is to provide a propylene-butene copolymer and a method for preparing the same. The copolymer has the advantages of a low content of xylene solubles, a narrow molecular weight distribution, and a low content of small molecules, and does not contain phthalate plasticizers, so it can be advantageously used in fields such as food packaging materials, pharmaceuticals, and healthcare.

[0008] Accordingly, in a first embodiment, the present invention provides a propylene-butene copolymer. The propylene-butene copolymer comprises 90-99 mol% propylene structural units and 1-10 mol% butene structural units, preferably 91-97 mol% propylene structural units and 3-9 mol% butene structural units, based on the total moles of copolymer structural units, with a xylene-soluble content of ≤4 wt%, preferably ≤3 wt%, more preferably ≤2.8 wt%, even more preferably ≤2.5 wt%, and even more preferably ≤2.3 wt%, and the propylene-butene copolymer substantially contains no fraction having a molecular weight less than 1000. Preferably, the copolymer has a molecular weight distribution index Mw / Mn of less than 5, preferably less than 4.5, and more preferably less than 4.

[0009] In a second aspect, the present invention provides a propylene-butene copolymer. The propylene-butene copolymer contains 92-99 mol% propylene structural units and 1-8 mol% butene structural units, preferably 93-97 mol% propylene structural units and 3-7 mol% butene structural units, based on the total moles of copolymer structural units, and has a melt flow index of ≥20 g / 10 min, preferably 35-200 g / 10 min, more preferably 50-150 g / 10 min, even more preferably 50-100 g / 10 min, when measured at 230°C under a 2.16 kg load, and has a xylene-soluble content of ≤5% by weight, preferably ≤4% by weight, more preferably ≤3% by weight, even more preferably ≤2.8% by weight, even more preferably ≤2.5% by weight, and even more preferably ≤2.3% by weight.

[0010] In a third embodiment, the present invention provides a method for preparing a propylene-butene copolymer. The method comprises the step of polymerizing propylene and butene under olefin polymerization reaction conditions in the presence of a catalyst and optionally selected hydrogen to obtain a propylene-butene copolymer, wherein the catalyst is a Ziegler-Natta catalyst comprising a solid catalyst component, an alkylaluminum compound and optionally selected external electron donor compound, the solid catalyst component being (i) Magnesium-containing compounds and; (ii) Titanium-containing compounds; (iii) Internal electron donor and The reaction product includes, The internal electron donor includes phosphate compounds and diether compounds.

[0011] In some embodiments, the method further comprises carrying out a pre-contact reaction of a solid catalyst component, an alkylaluminum compound, and an optional external electron donor compound, and, after the pre-contact reaction and before the polymerization reaction, carrying out a pre-polymerization reaction using a propylene monomer and / or other α-olefin monomer (e.g., ethylene or butene) and an optional hydrogen in the presence of the pre-contacted catalyst.

[0012] In a fifth embodiment, the present invention provides the use of the above-mentioned propylene-butene copolymer in food and / or pharmaceutical and healthcare products.

[0013] The propylene-butene copolymer of the present invention has the advantages of a high melt flow index and low xylene soluble content, and does not contain phthalate plasticizers. Alternatively, the propylene-butene copolymer of the present invention has the advantages of low xylene soluble content and a narrow molecular weight distribution, and does not contain phthalate plasticizers. The above characteristics are beneficial for its application in the fields of food, pharmaceuticals, and healthcare.

[0014] Other features and advantages of the present invention are described in detail below.

[0015] [Best mode for carrying out the invention] Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are used solely to illustrate and illustrate the present invention, and not to limit it.

[0016] In a first embodiment, the present invention provides a propylene-butene copolymer. The propylene-butene copolymer contains 90-99 mol% propylene structural units and 1-10 mol% butene structural units, preferably 91-97 mol% propylene structural units and 3-9 mol% butene structural units, based on the total moles of copolymer structural units, with a xylene-soluble content of ≤4% by weight, preferably ≤3% by weight, more preferably ≤2.8% by weight, even more preferably ≤2.5% by weight, and even more preferably ≤2.3% by weight, and the propylene-butene copolymer substantially contains no fractions having a molecular weight less than 1000. As will be understood by those skilled in the art, the lower the content of small molecule fractions in the copolymer, the less leaching occurs in the article, and the greater the safety of the article when it comes into contact with the human body.

[0017] As used herein, the term "butene" means 1-butene unless otherwise specified.

[0018] In some embodiments, the copolymer has a molecular weight distribution index Mw / Mn of less than 5, preferably less than 4.5, and more preferably less than 4.

[0019] In this disclosure, the xylene-soluble content is measured according to GB / T 24282-2009, and the molecular weight distribution index and content (weight percent) of fractions having a molecular weight of less than 1000 are measured by gel permeation chromatography (GPC). Specifically, a Shimadzu LC-10AT gel permeation chromatograph (GPC) can be used, in which trichlorobenzene is used as the mobile phase and the temperature is 150°C.

[0020] In this disclosure, the expression "the propylene-butene copolymer is substantially free of fractions having a molecular weight of less than 1000" means that, when measured by GPC, the propylene-butene copolymer contains fractions having a molecular weight of less than 1000 g / mol, preferably less than 0.015% by weight, and more preferably less than 0.005% by weight. In some embodiments, the propylene-butene copolymer of the present invention is measured by GPC, and the measurement results indicate that the content of fractions having a molecular weight of less than 1000 g / mol is zero.

[0021] In some embodiments, the propylene-butene copolymer is characterized by the absence of phthalate ester plasticizers, in addition to the low content of xylene-soluble substances, narrow molecular weight distribution, and low content of small molecules mentioned above.

[0022] In a second aspect, the present invention provides a propylene-butene copolymer. The propylene-butene copolymer contains 92-99 mol% propylene structural units and 1-8 mol% butene structural units, preferably 93-97 mol% propylene structural units and 3-7 mol% butene structural units, based on the total moles of copolymer structural units, and has a melt flow index of ≥20 g / 10 min, preferably 35-200 g / 10 min, more preferably 50-150 g / 10 min, even more preferably 50-100 g / 10 min, when measured at 230°C under a 2.16 kg load, and has a xylene-soluble content of ≤5% by weight, preferably ≤4% by weight, more preferably ≤3% by weight, even more preferably ≤2.8% by weight, even more preferably ≤2.5% by weight, and even more preferably ≤2.3% by weight.

[0023] In this disclosure, the melt flow index is measured according to GB / T 3682-2000.

[0024] In some embodiments, the propylene-butene copolymer is characterized by the absence of phthalate plasticizers, in addition to the high melt flow index and low xylene content described above. As used herein, the expression "phthalate plasticizer-free" means that the propylene-butene copolymer does not contain phthalate plasticizers that have been intentionally added.

[0025] In a third embodiment, the present invention provides a method for preparing a propylene-butene copolymer. The method comprises the step of polymerizing propylene and butene under olefin polymerization reaction conditions in the presence of a catalyst and optionally selected hydrogen to obtain a propylene-butene copolymer, wherein the catalyst is a Ziegler-Natta catalyst comprising a solid catalyst component, an alkylaluminum compound and optionally selected external electron donor compound, the solid catalyst component being (i) Magnesium-containing compounds and; (ii) Titanium-containing compounds; (iii) Internal electron donor and The reaction product includes, The internal electron donor includes phosphate compounds and diether compounds.

[0026] In some embodiments, the olefin polymerization reaction is carried out in the presence of hydrogen, where the hydrogen concentration in the polymerization system is ≥1200 ppm, preferably in the range of 1800 to 8000 ppm, and more preferably in the range of 2300 to 6000 ppm.

[0027] In some embodiments, propylene and butene are used in the method in such amounts that the copolymer contains, based on the total moles of copolymer structural units, 92 to 99 mol% of propylene structural units and 1 to 8 mol% of butene structural units, preferably 93 to 97 mol% of propylene structural units and 3 to 7 mol% of butene structural units.

[0028] In other embodiments, propylene and butene are used in the process in amounts such that the copolymer contains 90 to 99 mol% propylene structural units and 1 to 10 mol% butene structural units, preferably 91 to 97 mol% propylene structural units and 3 to 9 mol% butene structural units, based on the total moles of copolymer structural units.

[0029] According to the present invention, the total content of the phosphate compound and the diether compound is preferably 70 to 100% by weight, more preferably 80 to 100% by weight, still more preferably 90 to 100% by weight, and most preferably 100% by weight, based on the weight of the internal electron donor.

[0030] In some preferred embodiments, the solid catalyst component does not contain a phthalic acid ester compound as an internal electron donor.

[0031] In the present invention, the type of the phosphate compound is not particularly limited and may be various existing phosphate compounds that can be used as an internal electron donor in an olefin polymerization catalyst. Preferably, the phosphate compound is at least one of the phosphate compounds represented by the formula (1).

Chemical formula

[0032] More preferably, the phosphate compound is trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tris(o-, m- or p-tolyl) phosphate, tris(o-, m- or p-cumyl) phosphate, tris(o-, m- or p-methoxyphenyl) phosphate, phenyldimethyl phosphate, (o-, m- or p-tolyl)dibutyl phosphate, (o-, m- or p-cumyl)dimethyl phosphate, (o-, m- or p-cumyl)diethyl phosphate, (o-, m- or At least one selected from p-cumyl)dibutyl phosphate, phenyldi(o-, m- or p-tolyl) phosphate, phenyldi(o-, m- or p-cumyl) phosphate, 2,5-dimethylphenyldibutyl phosphate, 3,5-dimethylphenyldibutyl phosphate, 2,5-diisopropylphenyldimethyl phosphate, 2,5-diisopropylphenyldiethyl phosphate, 2,5-di-tert-butylphenyldimethyl phosphate, and o-tolylbis(2,5-di-tert-butylphenyl) phosphate.

[0033] Most preferably, the phosphate compound is tributyl phosphate.

[0034] In the present invention, the type of diether compound is not particularly limited and can be any existing diether compound that can be used as an internal electron donor in an olefin polymerization catalyst. Preferably, the diether compound is at least one of the diether compounds represented by formula (2). [ka] In the formula, R I , R II , R III , R IV , R V and R VI They are the same or different, and each is independently hydrogen, halogen atom, and C1-C 20 Linear or branched alkyl, C3-C 20 Cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkali and C7-C 20 Selected from the group consisting of aralkyls, R I -R VI The elements are linked by any choice to form a ring; R VII and R VIII They are either the same or different, and each is independently C1-C 20 Linear or branched alkyl, C3-C 20 Cycloalkyl, C6-C 20 Aryl, C7-C 20 Alkali and C7-C 20 Selected from a group consisting of aralkyls.

[0035] Preferably, the diether compound is 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane, 2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane, 2-(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-(p-chlorophenyl)-1,3-dimethoxypropane, 2-(diphenyl Dimethyl)-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-methyl-2-benzyl-1,3-dimethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2-methyl-2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-methyl-2-isobutyl-1,3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-dibenzyl-1,3-dimethoxypropane Cypropane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2-(1-methylbutyl)-2-isopropyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-phenyl-2-isopropyl-1,3-dimethoxypropane, 2-phenyl-2-sec-butyl-1,3-dimethoxypropane, 2-benzyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1,It is at least one selected from 3-dimethoxypropane, 2-cyclopentyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, and 9,9-dimethoxymethylfluorene.

[0036] Most preferably, the diether compound is 2-isopropyl-2-isopentyl-1,3-dimethoxypropane and / or 9,9-dimethoxymethylfluorene.

[0037] In the present invention, the phosphate compound and the diether compound are used in combination as internal electron donors, and the molar ratio of the phosphate compound to the diether compound is preferably controlled to 0.02 to 0.30:1, for example 0.02 to 0.28:1, more preferably to 0.03 to 0.25:1, for example 0.04 to 0.25:1, and even more preferably to 0.04 to 0.20:1, for example 0.05 to 0.20:1. This effectively improves the sensitivity and stereospecificity of the catalyst to hydrogen adjustment, helps to reduce the xylene-soluble content of the polymer, and allows the resulting polymer to have a narrower molecular weight distribution.

[0038] In the present invention, the magnesium-containing compound can be various magnesium-containing compounds that can be used as catalysts for olefin polymerization. For example, the magnesium-containing compound may be magnesium halide, magnesium alkoxide, alkoxymagnesium halide, or magnesium halide adduct support. Magnesium halide may be, for example, magnesium chloride and / or magnesium bromide; magnesium alkoxide may be, for example, diethoxymagnesium; and alkoxymagnesium halide may be, for example, ethoxymagnesium chloride. The types of magnesium halide adduct support are well known to those skilled in the art and are disclosed, for example, in CN1091748A, CN101050245A, CN101486722A, 201110142357.X, 201110142156.X and 201110142024.7 (all relevant content of these is incorporated herein by reference).

[0039] According to the present invention, the titanium-containing compound may be a conventional choice in the art. For example, the titanium-containing compound may have the general formula Ti(OR') 3-a Z a and Ti(OR') 4-b Z b (In the formula, R' is C1-C) 20 Alkyl, preferably C1-C 12 The titanium-containing compound may be at least one of the titanium-containing compounds represented as alkyl, more preferably C1-C6 alkyl, where Z is a halogen containing F, Cl, Br, or I, a is an integer from 1 to 3, and b is an integer from 1 to 4. Preferably, the titanium-containing compound is one or more of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, tributoxytitanium chloride, dibutoxytitanium dichloride, butoxytitanium trichloride, triethoxytitanium chloride, diethoxytitanium dichloride, ethoxytitanium trichloride, and titanium trichloride.

[0040] The content of magnesium, titanium, and internal electron donors in the solid catalyst component is not particularly limited in the present invention and may be any of the content observed in conventional solid catalyst components in the art. Preferably, the content of magnesium is 2 to 16 parts by weight, preferably 3 to 13 parts by weight, more preferably 4 to 10 parts by weight, per 1 part by weight of titanium, and the content of internal electron donors is 2 to 16 parts by weight, preferably 3 to 14 parts by weight, more preferably 4 to 12 parts by weight.

[0041] In the present invention, the alkylaluminum compound may be various alkylaluminum compounds that have been conventionally used in the art. For example, the alkylaluminum compound may have the general formula AlR 16 R 16 'R 16 ''(In the formula, R 16 , R 16 'and R 16 '' may be at least one of the compounds represented by (each independently being a C1-C8 alkyl or halogen, at least one of which is a C1-C8 alkyl, and the hydrogen atoms on the alkyl may optionally be substituted with halogens). Specific examples of C1-C8 alkyl groups include, but are not limited to, methyl, ethyl, propyl, n-butyl, isobutyl, pentyl, hexyl, n-heptyl, and n-octyl groups, and halogens may be fluorine, chlorine, bromine, and iodine. Specifically, alkylaluminum compounds may be one or more selected from the group consisting of, for example, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, diethylaluminum monochloride, diisobutylaluminum monochloride, di-n-butylaluminum monochloride, di-n-hexylaluminum monochloride, monoethylaluminum dichloride, isobutylaluminum dichloride, mono-n-butylaluminum dichloride, and n-hexylaluminum dichloride.

[0042] According to the present invention, the amount of alkylaluminum compound used can be the amount commonly used in the art. Preferably, the molar ratio of aluminum in the alkylaluminum compound to titanium in the solid catalyst component is 1 to 1000:1. More preferably, the molar ratio of aluminum in the alkylaluminum compound to titanium in the solid catalyst component is 20 to 500:1. Most preferably, the molar ratio of aluminum in the alkylaluminum compound to titanium in the solid catalyst component is 30 to 200:1.

[0043] In the present invention, the external electron donor compound can be one or more of the following: carboxylic acids, carboxylic acid anhydrides, carboxylic acid esters, ketones, ethers, alcohols, lactones, organophosphorus compounds, and organosilicon compounds, and other various external electron donor compounds commonly used in the art.

[0044] According to a preferred embodiment of the present invention, the external electron donor compound is at least one of the organosilicon compounds represented by formula X. (R 17 ) m’ (R 18 ) p’ Si(OR 19 ) q’ formula (In the formula, R 17 , R 18 and R 19 These are, independently, C1-C 18 It is a hydrocarbon group, which may optionally contain a halogen; m' and p' are each independently integers between 0 and 2, q' is an integer between 1 and 3, and the sum of m', p', and q' is 4; Preferably, R 17 and R 18 These are, independently, C3-C 10 Linear or branched alkyl, C3-C 10 Alkenyl, C3-C 10 Cycloalkyl or C6-C 10 It is an aryl compound and may optionally contain a halogen; R 19 C1-C 10A linear or branched alkyl group, preferably a C1-C4 linear or branched alkyl group, more preferably a methyl group.

[0045] Preferably, the organosilicon compound is at least one selected from cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, cyclohexyltrimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, tert-butyltrimethoxysilane, tert-hexyltrimethoxysilane, and 2-ethylpiperidinyl-2-tert-butyldimethoxysilane.

[0046] When used, the external electron donor can be added directly to the reactor or to equipment and lines related to supplying the reactor.

[0047] According to the present invention, the molar ratio of aluminum to the external electron donor compound in the alkylaluminum compound is preferably 1 to 50:1, more preferably 2 to 20:1. By controlling the amounts of the alkylaluminum compound and the external electron donor compound within the above preferred range, the properties of the resulting polymer can be further improved.

[0048] According to this aspect of the present invention, during the preparation of the olefin polymer, the catalyst may be added directly to the reactor or added to the reactor after precomplexing and / or prepolymerization.

[0049] Polymerization of propylene and butene can be carried out according to known methods, in an inert solvent containing a liquid-phase monomer or a polymerizable monomer, in the gas phase, or by a combined polymerization process in the gas and liquid phases. The polymerization temperature can be in the range of 10 to 150°C, preferably 60 to 90°C, and the polymerization pressure can be higher than the saturated vapor pressure of propylene at the corresponding polymerization temperature, for example, in the range of 0.01 to 10 MPa, preferably 0.05 to 5 MPa, more preferably 0.1 to 4 MPa. As used herein, pressure refers to gauge pressure.

[0050] The type and amount of inert gas and solvent used during the polymerization reaction may be conventional choices in the art.

[0051] The polymerization methods described herein are suitable for currently mature, large-scale processes such as the Spheripol process and the Hypol process.

[0052] In some embodiments, the method of the present invention further comprises a pre-contact reaction of a solid catalyst component, an alkylaluminum compound, and an optional external electron donor compound to provide a pre-contacted catalyst, and a pre-polymerization reaction after the pre-contact reaction and before the polymerization reaction, in the presence of a propylene monomer and / or other α-olefin monomer (e.g., ethylene or butene) and optionally hydrogen.

[0053] In some embodiments, the temperature of the pre-contact reaction is in the range of -10 to 30°C, preferably 0 to 15°C, and the duration of the pre-contact reaction is in the range of 0.05 to 30 minutes, preferably 0.1 to 10 minutes. By performing the pre-contact reaction, the polymerization activity and stereospecificity of the catalyst, as well as the bulk density of the resulting polymer, can be significantly improved, the impurity resistance of the catalyst's active center can be increased, and thereby the breakdown of ash, xylene-soluble matter, and polymer particles in the polymer can be reduced.

[0054] It is preferable to subject the catalyst to a prepolymerization reaction with a propylene monomer and / or other α-olefin monomer after the pre-contact reaction and before the polymerization reaction. A small amount of hydrogen may or may not be added during the prepolymerization, the temperature of the prepolymerization reaction is in the range of 10 to 50°C, preferably 12 to 25°C, more preferably 15 to 19°C, and the duration of the prepolymerization reaction is in the range of 1 to 40 minutes, preferably 5 to 20 minutes.

[0055] Polymerization of propylene and butene can be carried out according to known methods in an inert solvent containing liquid-phase monomers or polymerizable monomers, or in the gas phase, or by a combined polymerization process in the gas and liquid phases. The polymerization temperature is typically 50 to 150°C, preferably 60 to 90°C. The polymerization reaction pressure is above atmospheric pressure, for example, 0.01 to 10 MPa, preferably 0.05 to 5 MPa, more preferably 1 to 4 MPa. Where used herein, pressure refers to gauge pressure. During polymerization, hydrogen gas can be added to the polymerization reactor as a polymer molecular weight modifier to adjust the molecular weight and melt index of the polymer. The residence time of the reaction monomers and catalyst in the polymerization reactor is in the range of 0.5 to 6 hours, preferably 1 to 4 hours.

[0056] The type and amount of inert gas and solvent used during the olefin polymerization reaction may be conventional choices in the art.

[0057] The present invention further provides a propylene-butene copolymer prepared by the above preparation method.

[0058] The copolymer of the present invention can be incorporated into a composition. The composition may contain additives commonly used in the art, such as antioxidants, halogen absorbers, antistatic agents, slip agents, and nucleating agents.

[0059] The present invention further provides the use of propylene-butene copolymer in fields such as food and / or healthcare products, for example, as a packaging material for food and / or healthcare products.

[0060] [Examples] The present invention will be further described below with reference to examples, but the scope of the present invention is not limited to these examples.

[0061] The copolymer composition was determined by infrared spectroscopy (FT-IR) analysis performed using a Nicolet Instruments 6700 infrared spectrometer.

[0062] The melt flow index of the copolymer was measured according to GB / T 3682-2000 at 230°C under a load of 2.16 kg.

[0063] The xylene-soluble content of the copolymer was measured according to GB / T 24282-2009.

[0064] In this invention, the molecular weight distribution index and the content (weight percentage) of fractions containing polymers with a molecular weight of less than 1000 were measured by gel permeation chromatography (GPC). Specifically, a Shimadzu LC-10AT gel permeation chromatograph (GPC) was used, with trichlorobenzene as the mobile phase and a temperature of 150°C.

[0065] Example 1 This example is used to illustrate the propylene-butene copolymer according to the present invention and a method for preparing the same.

[0066] (1) Preparation of catalyst components In a 300 ml glass reactor, 90 ml of titanium tetrachloride was added and cooled to -20°C. Then, 37 mmol (magnesium equivalent) of magnesium halide support (prepared according to the method disclosed in Example 1 of CN1330086A) was added. The contents were heated to 110°C, and during the heating process, 0.8 mmol of tributyl phosphate and 7.9 mmol of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were added. After maintaining the reaction mixture at 110°C for 30 minutes, the liquid was filtered off, the solid was washed with titanium tetrachloride and then hexane, and dried under vacuum to obtain catalyst component Cat-1.

[0067] (2) Preparation of propylene-butene copolymer Propylene, butene, and hydrogen gas were supplied to the reactor, and catalyst component (Cat-1), triethylaluminum, and cyclohexylmethyldimethoxysilane (the molar ratio of catalyst component Cat-1 in terms of titanium element to triethylaluminum in terms of aluminum element was 1:160, and the molar ratio of cyclohexylmethyldimethoxysilane to triethylaluminum in terms of aluminum element was 1:5) were introduced into the reactor. The polymerization reaction was carried out under the following conditions: reaction temperature 69°C, reaction pressure 3.5 MPa, hydrogen concentration (detected by online chromatography) 1600 wppm, butene concentration in the reaction raw materials 5.4 mol%, and reaction time 1 hour. The resulting polymer was analyzed, and the results are shown in Table 1.

[0068] Example 2 This example is used to illustrate the propylene-butene copolymer according to the present invention and a method for preparing the same.

[0069] The catalyst component and polymer were prepared according to the method described in Example 1, except that the butene concentration in the reaction raw materials was 8.9 mol% during the polymer preparation process. The obtained polymer was analyzed, and the results are shown in Table 1.

[0070] Example 3 This example is used to illustrate the propylene-butene copolymer according to the present invention and a method for preparing the same.

[0071] The catalyst component and polymer were prepared according to the method described in Example 1, except that the reaction pressure was 3.6 MPa, the hydrogen concentration was 2500 ppm, the butene concentration in the reaction raw materials was 11 mol%, and the reaction time was 1.4 hours. The obtained polymer was analyzed, and the results are shown in Table 1.

[0072] Example 4 This example is used to illustrate the propylene-butene copolymer according to the present invention and a method for preparing the same.

[0073] In polymerization, the catalyst component and polymer were prepared according to the method described in Example 3, except that the hydrogen concentration was 3100 ppm and the butene concentration in the reaction raw materials was 9.1 mol%. The obtained polymer was analyzed, and the results are shown in Table 1.

[0074] Example 5 This example is used to illustrate the propylene-butene copolymer according to the present invention and a method for preparing the same.

[0075] The catalyst component was prepared according to the method described in Example 1, except that 1.3 mmol of tributyl phosphate and 7 mmol of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were added during the heating process to obtain catalyst component Cat-2.

[0076] A polymer was prepared according to the method described in Example 1, except that the molar ratio of the catalyst component Cat-2 (calculated on a titanium basis) to triethylaluminum (calculated on an aluminum basis) was 1:100, the molar ratio of cyclohexylmethyldimethoxysilane to triethylaluminum (calculated on an aluminum basis) was 1:3.5, the hydrogen concentration was 2000 ppm, and the butene concentration in the reaction raw materials was 7 mol%.

[0077] Comparative Example 1 The polymer was prepared according to the method described in Example 2, except that the catalyst component Cat-1 was replaced with a DQC catalyst component (containing diisobutyl phthalate as an internal electron donor) purchased from Sinopec Catalyst Co., Ltd. Beijing Aoda Branch. The obtained polymer was analyzed, and the results are shown in Table 1.

[0078] [Table 1]

[0079] The results from the examples and comparative examples show that the propylene-butene copolymer of the present invention has a high melt flow index and a low content of xylene-soluble substances, and that the catalyst used in the present invention does not contain phthalate esters (plasticizers), so the polymer can be advantageously used in the fields of food and healthcare.

[0080] Example 6 This example is used to illustrate a method for preparing a propylene-butene copolymer according to the present invention.

[0081] (1) Preparation of catalyst components In a 300 ml glass reactor, 90 ml of titanium tetrachloride was added and cooled to -20°C. Then, 37 mmol (magnesium equivalent) of magnesium halide support (prepared according to the method disclosed in Example 1 of CN1330086A) was added. The contents were heated to 110°C, and during the heating process, 0.9 mmol of tributyl phosphate and 8.3 mmol of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were added. After maintaining the reaction mixture at 110°C for 30 minutes, the liquid was filtered off, the solid was washed with titanium tetrachloride and then hexane, and dried under vacuum to obtain catalyst component Cat-3.

[0082] (2) Preparation of polypropylene Propylene, butene, and hydrogen gas were supplied to the reactor. The catalyst component (Cat-3), triethylaluminum, and cyclohexylmethyldimethoxysilane (the molar ratio of catalyst component Cat-3 in terms of titanium element to triethylaluminum in terms of aluminum element was 1:120, and the molar ratio of cyclohexylmethyldimethoxysilane to triethylaluminum in terms of aluminum element was 1:4) were pre-contacted at 10°C for 5 minutes, then subjected to a pre-polymerization reaction at 18°C ​​for 12 minutes, and then introduced into the polymerization reactor. The polymerization reaction was carried out under the following conditions: reaction temperature 69°C, reaction pressure 3.5 MPa, hydrogen concentration (detected by online chromatography) 1300 ppm, butene concentration in the reaction raw materials 6 mol%, and reaction time 1 hour. The obtained polymer was analyzed, and the results are shown in Table 2.

[0083] Example 7 This example is used to illustrate a method for preparing a propylene-butene copolymer according to the present invention.

[0084] In preparing the polymer, the catalyst component and polymer were prepared according to the method described in Example 6, except that the butene concentration in the reaction raw materials was 11.5 mol%. The obtained polymer was analyzed, and the results are shown in Table 2.

[0085] Example 8 This example is used to illustrate a method for preparing a propylene-butene copolymer according to the present invention.

[0086] In polymerization, the catalyst component and polymer were prepared according to the method described in Example 6, except that the hydrogen concentration was 2000 ppm, the preliminary contact reaction was carried out at 8°C for 6 minutes, and the butene concentration in the reaction raw materials was 9 mol%. The obtained polymer was analyzed, and the results are shown in Table 2.

[0087] Example 9 The catalyst component was prepared according to the method described in Example 6, except that 1.4 mmol of tributyl phosphate and 8 mmol of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were added during the heating process to obtain catalyst component Cat-4.

[0088] The polymer was prepared according to the method described in Example 6, except that the molar ratio of the catalyst component Cat-4 (calculated on a titanium basis) to triethylaluminum (calculated on an aluminum basis) was 1:80, the molar ratio of cyclohexylmethyldimethoxysilane to triethylaluminum (calculated on an aluminum basis) was 1:7, the hydrogen concentration was 1000 ppm, and the butene concentration in the reaction raw materials was 7 mol%.

[0089] Comparative Example 2 The polymer was prepared according to the method described in Example 8, except that the catalyst component Cat-3 was replaced with a DQC catalyst component (containing diisobutyl phthalate as an internal electron donor) purchased from Sinopec Catalyst Co., Ltd. Beijing Aoda Branch. The obtained polymer was analyzed, and the results are shown in Table 2.

[0090] [Table 2]

[0091] The results from Examples 6-9 and Comparative Example 2 show that the propylene-butene copolymer of the present invention has the characteristics of low xylene content, a narrow molecular weight distribution, and small molecules, and that because the present invention utilizes a catalyst that does not contain phthalate esters (plasticizers), the polymer can be advantageously used in the fields of food and healthcare.

[0092] Although various embodiments of the present invention have been described above, the above description is illustrative and not exhaustive, and is not limited to the disclosed embodiments. Many changes and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the embodiments described.

[0093] The endpoints of the ranges and any values ​​disclosed herein are not limited to exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, one or more new numerical ranges can be obtained by combining the values ​​at the ends of individual ranges, the boundary values ​​of individual ranges and the values ​​of individual points between them, and the values ​​of individual points with each other. One or more new numerical ranges should be considered to be specifically disclosed herein.

Claims

1. The process includes the step of polymerizing propylene and butene under olefin polymerization reaction conditions, in the presence of a catalyst and optionally selected hydrogen, to obtain a propylene-butene copolymer. The catalyst is a Ziegler-Natta catalyst, comprising a solid catalyst component, an alkylaluminum compound, and an optional external electron donor compound. The aforementioned solid catalyst component is (i) Magnesium-containing compounds; (ii) Titanium-containing compounds; (iii) Internal electron donor and The reaction product includes, The internal electron donor is a method for preparing a propylene-butene copolymer, comprising a phosphate compound and a diether compound. The propylene-butene copolymer comprises 90 to 99 mol% propylene structural units and 1 to 10 mol% butene structural units based on the total moles of copolymer structural units, the composition of the copolymer is determined by Fourier infrared spectroscopy, and the copolymer has a xylene-soluble content of ≤4% by weight, as measured according to GB / T 24282-2009. The propylene-butene copolymer comprises a fraction having a molecular weight of less than 0.015% by weight and less than 1000 g / mol, as measured by GPC, and the copolymer has a molecular weight distribution index Mw / Mn of less than 4.5, as measured by gel permeation chromatography.

2. The aforementioned olefin polymerization reaction is carried out in the presence of hydrogen. The method according to claim 1, wherein the hydrogen concentration in the polymerization system on a molar basis is ≥ 1200 ppm.

3. The method according to claim 2, wherein the hydrogen concentration in the polymerization system on a molar basis is in the range of 1800 to 8000 ppm.

4. The method according to claim 1 or 2, further comprising: performing a preliminary catalytic reaction of the solid catalyst component, the alkylaluminum compound, and the optionally selected external electron donor compound to provide a pre-contacted catalyst; and, after the preliminary catalytic reaction and before the polymerization reaction, performing a preliminary polymerization reaction in the presence of the pre-contacted catalyst using a propylene monomer and / or other α-olefin monomer and optionally hydrogen.

5. The method according to any one of claims 1 to 4, wherein the propylene and the butene are used in the polymerization in such amounts that the copolymer contains 90 to 99 mol% of propylene structural units and 1 to 10 mol% of butene structural units based on the total moles of copolymer structural units, and the composition of the copolymer is determined by Fourier infrared spectroscopy.

6. The method according to any one of claims 1 to 5, having at least one of the following features: - The total content of the phosphate compound and the diether compound is 70 to 100% by weight, based on the weight of the internal electron donor; - The phosphate compound is at least one of the phosphate compounds represented by formula (1); 【Chemistry 1】 wherein, R １３ , R １４ and R １５ are each independently selected from the group consisting of C １ -C ２０ linear or branched alkyl, C ３ -C ２０ cycloalkyl, C ６ -C ２０ aryl, C ７ -C ２０ alkaryl and C ７ -C ２０ aralkyl, and the hydrogen atoms in the benzene ring of the aryl, the alkaryl and the aralkyl are optionally substituted by a halogen atom or C １ -C ４ alkoxy; or The phosphate compounds mentioned above are trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tris(o-, m- or p-tolyl) phosphate, tris(o-, m- or p-cumyl) phosphate, tris(o-, m- or p-methoxyphenyl) phosphate, phenyldimethyl phosphate, (o-, m- or p-tolyl) dibutyl phosphate, (o-, m- or p-cumyl) dimethyl phosphate, (o-, m- or p-cumyl) diethyl phosphate, (o-, m- or p-cumyl) At least one selected from o-tolylbis(2,5-di-tert-butylphenyl)phosphate, phenyldi(o-,m-, or p-tolyl)phosphate, phenyldi(o-,m-, or p-cumyl)phosphate, 2,5-dimethylphenyldibutylphosphate, 3,5-dimethylphenyldibutylphosphate, 2,5-diisopropylphenyldimethylphosphate, 2,5-diisopropylphenyldiethylphosphate, 2,5-di-tert-butylphenyldimethylphosphate, and o-tolylbis(2,5-di-tert-butylphenyl)phosphate; - The diether compound is at least one of the diether compounds represented by formula (2): 【Chemistry 2】 In the formula, R Ｉ , R ＩＩ , R ＩＩＩ , R ＩＶ , R Ｖ and R ＶＩ They are the same or different, and each is independently hydrogen, halogen atom, and C １ -C ２０ Linear or branched alkyl, C ３ -C ２０ Cycloalkyl, C ６ -C ２０ Ariel, C ７ -C ２０ Alkali and C ７ -C ２０ Selected from the group consisting of aralkyl, R Ｉ -R ＶＩ The elements are optionally connected to form a ring; R ＶＩＩ and R ＶＩＩＩ They are the same or different, and each is independent of C １ -C ２０ Linear or branched alkyl, C ３ -C ２０ Cycloalkyl, C ６ -C ２０ Ariel, C ７ -C ２０ Alkali and C ７ -C ２０ Selected from a group consisting of aralkyls; or The diether compounds are 2-(2-ethylhexyl)-1,3-dimethoxypropane, 2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane, 2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane, 2-(2-phenylethyl)-1,3-dimethoxypropane, 2-(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-(p-chlorophenyl)-1,3-dimethoxypropane, and 2-(diphenylmethyl (L)-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-dimethoxypropane, 2,2-dipropyl-1,3-dimethoxypropane, 2,2-diisopropyl-1,3-dimethoxypropane, 2,2-dibutyl-1,3-dimethoxypropane, 2-methyl-2-propyl-1,3-dimethoxypropane, 2-methyl-2-benzyl-1,3-dimethoxypropane, 2-methyl-2-ethyl-1,3-dimethoxypropane, 2- Methyl-2-isopropyl-1,3-dimethoxypropane, 2-methyl-2-phenyl-1,3-dimethoxypropane, 2-methyl-2-cyclohexyl-1,3-dimethoxypropane, 2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane, 2-methyl-2-isobutyl-1,3-dimethoxypropane, 2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-diphenyl-1,3-dimethoxypropane, 2,2-dibenzyl-1,3-dimethoxypropane Propane, 2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane, 2-isobutyl-2-isopropyl-1,3-dimethoxypropane, 2-(1-methylbutyl)-2-isopropyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2-phenyl-2-isopropyl-1,3-dimethoxypropane, 2-phenyl-2-sec-butyl-1,3-dimethoxypropane, 2-benzyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclopentyl-2-isopropyl-1,At least one selected from 3-dimethoxypropane, 2-cyclopentyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-isopropyl-1,3-dimethoxypropane, 2-cyclohexyl-2-sec-butyl-1,3-dimethoxypropane, 2-isopropyl-2-sec-butyl-1,3-dimethoxypropane, 2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane, and 9,9-dimethoxymethylfluorene; - The molar ratio of the phosphate compound to the diether compound is 0.02 to 0.30:1; - The magnesium-containing compound is at least one of magnesium halides, magnesium alkoxides, magnesium alkoxyhalides, and magnesium halide adducts; - The titanium-containing compound has the general formula Ti(OR') ３－ａ Z ａ and Ti(OR') ４－ｂ Z ｂ At least one of the titanium-containing compounds represented by the formula, where R' is C １ -C ２０ It is an alkyl group; Z is a halogen; a is an integer from 1 to 3, and b is an integer from 1 to 4; - In the solid catalyst component, the content of magnesium element is 2 to 16 parts by weight per 1 part by weight of titanium element; the content of the internal electron donor is 2 to 16 parts by weight; - The alkylaluminum compound has the general formula AlR １６ R １６ 'R １６ At least one of the compounds represented by '', where R １６ , R １６ 'and R １６ Each of the '' is independent of C １ -C ８ It is an alkyl or halogen, and at least one of them is C １ -C ８ It is an alkyl group, and the hydrogen atoms on the alkyl group are optionally substituted with halogens; - The molar ratio of aluminum in the alkylaluminum compound to titanium in the solid catalyst component is 1 to 1000:1; - The molar ratio of aluminum in the alkylaluminum compound to the external electron donor compound is 1 to 50:1; - The external electron donor compound is at least one of the organosilicon compounds represented by formula X. (R １７ ) ｍ’ (R １８ ) ｐ’ Si(OR １９ ) ｑ’ Formula X In the formula, R １７ , R １８ and R １９ Each of them is independent of C １ -C １８ It is a hydrocarbon group, optionally containing a halogen; m' and p' are each independently integers from 0 to 2, q' is an integer from 1 to 3, and the sum of m', p', and q' is 4; or The organosilicon compound is at least one selected from cyclohexylmethyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, diphenyldimethoxysilane, methyl-tert-butyldimethoxysilane, dicyclopentyldimethoxysilane, cyclohexyltrimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, tert-butyltrimethoxysilane, tert-hexyltrimethoxysilane, and 2-ethylpiperidinyl-2-tert-butyldimethoxysilane; - The temperature of the olefin polymerization reaction is in the range of 10 to 150°C; - The pressure for the olefin polymerization reaction is in the range of 0.01 to 10 MPa; - The residence time of the reaction monomers and the catalyst in the polymerization reactor is in the range of 0.5 to 6 hours; - The temperature of the preliminary contact reaction is in the range of -10 to 30°C; - The duration of the preliminary contact reaction is in the range of 0.05 to 30 minutes; - A small amount of hydrogen gas is introduced into the prepolymerization reaction; - The temperature of the preliminary polymerization reaction is in the range of 10 to 50°C; - The duration of the preliminary polymerization reaction is in the range of 1 to 40 minutes.

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