A self-stabilized precipitation polymerization method using an ether-containing solvent

Abstract

The present invention relates to a self-stabilized precipitation polymerization method using an ether-containing solvent. The method of the present invention uses a solvent containing an ether compound as a polymerization reaction medium, wherein the boiling point of the ether compound is below 145 °C. By using a low-boiling ether solvent as the medium, the energy consumption of the solvent fractionation recovery operation is low, the solvent recycling is easy to carry out, the cost is low and it is more environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the field of self-stabilizing precipitation polymerization, and in particular relates to a self-stabilizing precipitation polymerization method using an ether-containing solvent. Background Art

[0002] Self-stabilized precipitation polymerization (2SP system) is a green, simple and efficient polymerization method proposed in recent years. Self-stabilized precipitation polymerization forms a stable colloid composed of polymer particles with uniform particle size and dispersion medium through static polymerization and self-nucleation-surface deposition growth process. Pure polymer products can be obtained through simple self-sedimentation, filtration or centrifugal separation. The separated supernatant can be used for the next polymerization without post-treatment problems, which has the advantage of "green polymerization process".

[0003] Non-patent document 1 proposes a self-stabilized precipitation polymerization method, which can prepare monodisperse polymer microspheres without adding any stabilizer during the reaction process. This polymerization method theoretically belongs to precipitation polymerization, but it is different from precipitation polymerization. The concentration of the self-stabilized precipitation polymerization reaction system is much higher than that of traditional precipitation polymerization, and the volume concentration is as high as 40% or more.

[0004] In Non-Patent Document 2, linear vinyl acetate-maleic anhydride copolymer microspheres with a monodisperse particle size of about 100 to 400 nm and a uniform particle size distribution are prepared by a self-stabilized precipitation polymerization method using alkyl esters as solvents.

[0005] In non-patent document 3, styrene-maleic anhydride polymer microspheres with a particle size of about 90-1700 nm and uniform particle size distribution were prepared by self-stabilizing precipitation polymerization, and the morphology and particle size were controllable.

[0006] In addition, 2SP also has many applications in the preparation of template materials, hollow polymer microspheres and certain high-performance materials. Especially in the field of mixed olefin polymerization and separation, the polymerization activity of the monomer can be improved by in-situ efficient alternating copolymerization of maleic anhydride with various olefins / dienes or aromatic olefins in the mixed components, and a series of polyolefin microsphere products containing anhydride functional groups can be prepared. The residual alkanes or aromatics can be recovered by simple distillation and can be used as high-value-added solvents and industrial raw materials, which is expected to solve the problem of "utilization of huge amounts of waste olefins worldwide".

[0007] The key to the self-stabilizing precipitation polymerization system is its self-stability. Non-patent document 4 proposes that Δδ = δ PMS -δ S , where δ PMS is the cohesive energy density of the polymer, δ Sis the solubility parameter of the solvent, and Δδ is the parameter related to the affinity between the solvent and the polymer. If the polymerization process is self-stabilized precipitation polymerization, then Δδ should be between 1.8 and 4.5 MPa 0.5 If Δδ < 1.8 MPa 0.5 it is solution polymerization. If Δδ > 4.5 MPa 0.5 it is ordinary precipitation polymerization. Based on this, a series of solvents such as esters and aromatics were screened out. For example, isopentyl acetate, toluene, xylene, and the mixed solvent of ethyl acetate / cyclohexane, etc. Their solubility parameters are shown in Table 1:

[0008] Table 1: Solubility parameters and boiling points of solvents for 2SP

[0009]

[0010] Currently, the reaction media of the known self-stabilized precipitation polymerization systems are mainly esters, aromatics, ketone solvents, and mixtures of these solvents and alkanes.

[0011] For example, in Patent Document 1, a method for preparing a polymer microsphere dispersion system by using an alkyl ester of organic acid as a solvent and the self-stabilized precipitation polymerization method was first proposed. Patent Document 2 discloses a copolymer of at least one of maleic anhydride, maleimide and its derivatives, and itaconic anhydride with C8 fraction, C9 fraction or light fraction of coal tar. The solvent system used to obtain this copolymer is an alkyl ester of organic acid, an aromatic hydrocarbon, or a mixture of a ketone and an alkane. Patent Document 3 discloses a copolymerization method of styrene and maleic anhydride, and the obtained styrene / maleic anhydride copolymer is microspheres with a dispersion coefficient of 1.04 - 1.004. The solvent system used in this polymerization system is an alkyl ester of organic acid or a mixed solvent of a ketone and an alkane. Patent Document 4 discloses a copolymer of maleic anhydride and C5 fraction, and the solvent system used to obtain this copolymer is an ester solvent such as isopentyl acetate.

[0012] As can be seen from the above Patent Documents 1 - 4, the published patents also use esters, aromatics and ketone solvents or mixed solvents as the polymerization medium and include them in the scope of patent protection. Therefore, all relevant patents in the field of self-stabilized precipitation polymerization currently do not involve ether solvents other than aryl ethers.

[0013] However, currently, the use of ether solvents other than aryl ethers in self-stabilized precipitation polymerization systems has not been reported.

[0014] Existing technical literature:

[0015] Non-patent literature:

[0016] Non-patent Document 1: Xing CM, et al., "A Novel, Facile Method for the Preparation of Uniform, Reactive Maleic Anhydride / Vinyl Acetate Copolymer Micro- and Nanospheres", Macromolecular Rapid Communications, 2004, 25(17): 1568-1574;

[0017] Non-patent Document 2: Xing CM, et al., "Surface Functionalization of Polypropylene Film via UV-Induced Photografting of N-Vinylpyrrolidone / Maleic Anhydride Binary Monomers", Macromolecular Chemistry and Physics, 2005, 206(11): 1106-1113;

[0018] Non-patent Document 3: Liu Zhenjie, et al., "Investigation on the Growth Mode of Monodisperse Styrene-Maleic Anhydride Copolymer Microspheres" (Journal of Beijing University of Chemical Technology: Natural Science Edition, 2010, 37(6): 5.);

[0019] Non-patent Document 4: According to Liu ZJ, et al., in "Self-Stabilized Precipitation Polymerization and Its Application.", Research, 2018(1): 12.

[0020] Patent Documents:

[0021] Patent Document 1: CN1247365C;

[0022] Patent Document 2: CN105949388A;

[0023] Patent Document 3: CN100579995A;

[0024] Patent Document 4: CN102690393B. Summary of the Invention

[0025] Problems to be Solved by the Invention

[0026] In actual laboratory tests and subsequent production conversion process tests, it was found that the known ester and aromatic solvent systems have problems such as difficult solid-liquid separation and high energy consumption in solvent recycling. In addition, due to the relatively high boiling points of ester and aromatic solvents during the solvent fractionation purification and recovery process, the energy consumption for solvent fractionation and recovery is relatively high, which is not conducive to the recycling of solvents.

[0027] Therefore, there is an urgent need to develop a self-stabilizing precipitation polymerization method that is environmentally friendly, easy for solvent fractionation and recovery, and has low energy consumption.

[0028] Solutions to solve the problems

[0029] In view of the above problems, the present inventors conducted in-depth research and believe that due to the solubility parameters of ester and aromatic solvents being too close to the cohesive energy density of maleic anhydride copolymers (δ PMS = 20.5 MPa 0.5 ), a large amount of solvent is entrapped in the polymer microspheres, resulting in difficulty in removing the solvent from the polymer microspheres.

[0030] The present inventors found that low-boiling ether solvents can not only ensure the smooth progress of self-stabilizing precipitation polymerization but also greatly reduce the subsequent solid-liquid separation cost. It is speculated that due to the solubility parameters and boiling points of ether solvents (as shown in Table 2 below) compared with ester and aromatic solvents, the overall solubility parameters of ether solvents are lower and Δδ is larger, so the affinity between the solvent and the polymer is poor; in addition, under the condition of the same carbon number, the boiling point of ether solvents is lower than that of ester solvents, so the energy consumption for fractionation and recovery of ether solvents is lower, which is more conducive to solvent recycling.

[0031] Based on the above findings, the present invention uses a solvent containing an ether compound as the reaction medium for self-stabilizing precipitation polymerization, thereby solving the above technical problems.

[0032] Specifically, the present invention solves the technical problems of the present invention through the following solutions.

[0033] [1] A self-stabilizing precipitation polymerization method, which uses a solvent containing an ether compound as the polymerization reaction medium, wherein the boiling point of the ether compound is below 145 °C.

[0034] [2] The self-stabilizing precipitation polymerization method according to [1], wherein the ether compound has a structure represented by formula (I) or formula (II):

[0035] R 1 -O-R 2 (I)

[0036] Wherein, R 1 and R 2 each independently represents an alkyl group having 1 to 5 carbon atoms;

[0037] R 3 -O-R 4 -O-R 5 (II)

[0038] Wherein, R 3 and R 5 independently of each other represent an alkyl group having 1 to 5 carbon atoms or benzyl, and R 4 represents an alkylene group having 1 to 5 carbon atoms;

[0039] or the ether compound is a cyclic ether having 3 to 20 carbon atoms.

[0040] [3] The self-stabilizing precipitation polymerization method according to [1] or [2], wherein the ether compound is one or more selected from dimethyl ether, methyl ethyl ether, diethyl ether, ethyl propyl ether, dipropyl ether, dibutyl ether, methyl propyl ether, methyl butyl ether, methyl isobutyl ether, methyl tert-butyl ether, methyl isopentyl ether, methyl tert-pentyl ether, methyl cyclopentyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane; preferably one or more selected from diethyl ether, dipropyl ether, methyl cyclopentyl ether, methyl tert-pentyl ether, ethylene glycol dimethyl ether, tetrahydrofuran; more preferably one or more selected from diethyl ether, methyl cyclopentyl ether.

[0041] [4] The self-stabilizing precipitation polymerization method according to [1] or [2], wherein the solvent further contains one or more compounds selected from aromatic hydrocarbons, alkanes, esters, and ketones, and the content of the ether compound in the solvent is 10% by mass or more.

[0042] [5] The self-stabilizing precipitation polymerization method according to [1] or [2], wherein the solvent consists of the ether compound.

[0043] [6] The self-stabilizing precipitation polymerization method according to [1] or [2], which includes the following steps:

[0044] Dissolve an electron-withdrawing monomer, an olefin monomer, and an initiator in the solvent and carry out a polymerization reaction.

[0045] [7] The self-stabilizing precipitation polymerization method according to [6], wherein,

[0046] the electron-withdrawing monomer is one or more selected from maleic anhydride, maleimide, itaconic anhydride, and their derivatives;

[0047] The olefin monomer is one or more selected from linear olefins, cyclic olefins, aromatic olefins, conjugated dienes and their derivatives having 2 to 15 carbon atoms; the monomer can be derived from at least one raw material selected from petroleum fractions (such as C4, C5 and C9 fractions), ethylene tar, by-product fractions above C4 from methanol to olefins, coal tar (such as dephenolized phenol oil), and crude gasoline (such as gasoline before etherification).

[0048] The initiator is one or more selected from peroxide initiators and azo compounds. The peroxide initiator is preferably benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, and the azo compound is preferably azobisisobutyronitrile, azobisisoheptonitrile.

[0049] [8] The self-stabilized precipitation polymerization method according to [6], wherein

[0050] The molar ratio of the electron-withdrawing monomer to the olefin monomer is (0.1 to 2):1, preferably (0.5 to 1.5):1;

[0051] The total mass concentration of the electron-withdrawing monomer and the olefin monomer in the reaction system is 0.1 to 50%, preferably 10 to 30%; the reaction system is composed of an electron-withdrawing monomer, an olefin monomer, an initiator and a solvent;

[0052] The mass concentration of the initiator in the reaction system is 0.04 to 0.5%.

[0053] [9] The self-stabilized precipitation polymerization method according to [6], wherein the temperature of the polymerization reaction is 40 to 120 °C; the polymerization reaction time is 0.01 to 24 hours; the polymerization reaction is carried out in an inert gas atmosphere.

[0054]

[10] The self-stabilized precipitation polymerization method according to [6], further comprising the following steps:

[0055] After the polymerization reaction, the reaction system is subjected to solid-liquid separation, and optionally the separated copolymer is dried.

[0056] Effect of the invention

[0057] The self-stabilized precipitation polymerization method of the present invention uses a low-boiling ether solvent as a medium, has low energy consumption for solvent fractionation and recovery operations, is easy to recycle the solvent, has low cost and is more environmentally friendly.

[0058] Specifically, the present invention has the following beneficial effects:

[0059] Since the present invention does not require the addition of any stabilizers and co-stabilizers, the reaction system is simple, the process control is easy, the cost is saved, and the environmental pollution is reduced;

[0060] The solvent used in the method of the present invention has a weak affinity with the polymer and a low boiling point, which is conducive to solid-liquid separation and solvent fractionation recovery;

[0061] The polymer microspheres prepared by the present invention have a clean surface, controllable particle size, controllable morphology, and narrow particle size distribution;

[0062] The process of the present invention is simple, the reaction rate is fast, the product is easy to separate, and the reaction medium used belongs to low-toxic chemicals and can be recycled. Description of the Drawings

[0063] Figure 1 It is a scanning electron microscope photograph of the copolymer obtained in Example 1;

[0064] Figure 2 It is a scanning electron microscope photograph of the copolymer obtained in Example 2;

[0065] Figure 3 It is a scanning electron microscope photograph of the copolymer obtained in Example 3;

[0066] Figure 4 It is a scanning electron microscope photograph of the copolymer obtained in Example 4;

[0067] Figure 5 It is a scanning electron microscope photograph of the copolymer obtained in Example 5;

[0068] Figure 6 It is a scanning electron microscope photograph of the copolymer obtained in Example 6;

[0069] Figure 7 It is a scanning electron microscope photograph of the copolymer obtained in Example 13;

[0070] Figure 8 It is a scanning electron microscope photograph of the copolymer obtained in Comparative Example 1;

[0071] Figure 9 It is the TGA spectrum of the copolymer obtained in Example 1;

[0072] Figure 10 It is the TGA spectrum of the copolymer obtained in Example 5;

[0073] Figure 11 It is the TGA spectrum of the copolymer obtained in Example 14;

[0074] Figure 12 It is the TGA spectrum of the copolymer obtained in Comparative Example 1;

[0075] Figure 13 It is the TGA spectrum of the copolymer obtained in Comparative Example 2;

[0076] Figure 14 It is the TGA spectrum of the copolymer obtained in Comparative Example 3. Detailed implementation manners

[0077] Terms and definitions

[0078] In this specification, "self-stabilized precipitation polymerization" refers to a polymerization method in which no emulsifier is used in the polymerization system and the polymerization product is suspended in the reaction medium.

[0079] In this specification, "particle size" refers to the median particle size D of the described particles 50 , which can be measured by a laser particle size analyzer.

[0080] In this specification, "electron-withdrawing monomer" refers to a monomer with an electron-withdrawing group on the carbon-carbon double bond participating in the polymerization reaction.

[0081] In this specification, unless otherwise clearly stated, "alkyl" means straight-chain, branched-chain or cyclic alkyl.

[0082] In this specification, the numerical range expressed by "numerical value A to numerical value B" refers to the range including the endpoint numerical values A and B.

[0083] In this specification, the numerical range expressed by "above" or "below" refers to the numerical range including this number.

[0084] In this specification, the meaning expressed by "can" includes both the meaning of performing a certain treatment and the meaning of not performing a certain treatment.

[0085] In this specification, the use of "optionally" or "optional" means that certain substances, components, execution steps, applied conditions, etc. are used or not used.

[0086] In this specification, the unit names used are all international standard unit names, and unless otherwise specified, the "%" used represents weight or mass percentage content.

[0087] In this specification, the "preferred implementation manners", "implementation manners", etc. mentioned refer to the specific elements (for example, features, structures, properties and / or characteristics) related to the implementation manner, which are included in at least one of the implementation manners described here, and may or may not exist in other implementation manners. In addition, it should be understood that the elements can be combined in various implementation manners in any suitable way.

[0088] One object of the present invention is to provide a self-stabilized precipitation polymerization method, which uses a solvent containing an ether compound (also referred to as an "ether-containing solvent") as a polymerization reaction medium, wherein the boiling point of the ether compound is below 145 °C.

[0089] By using an ether solvent with a relatively low boiling point in the reaction medium, the present invention not only ensures the smooth progress of self-stabilized precipitation polymerization but also achieves the effect that the solvent is easily separated and recovered.

[0090] In one embodiment, the ether compound used in the present invention has the structure shown in formula (I) or formula (II), or the ether compound is a cyclic ether having 3 to 20, preferably 4 to 10, more preferably 4 to 6 carbon atoms

[0091] R 1 -O-R 2 (I)

[0092] Wherein, R 1 and R 2 independently of each other represent an alkyl group having 1 to 5 carbon atoms, such as an alkyl group having 1, 2, 3, 4, or 5 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, cyclopropyl, cyclobutyl, cyclopentyl;

[0093] R 3 -O-R 4 -O-R 5 (II)

[0094] Wherein, R 3 and R 5 independently of each other represent an alkyl group having 1 to 5 carbon atoms or benzyl, such as an alkyl group having 1, 2, 3, 4, or 5 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, cyclopropyl, cyclobutyl, cyclopentyl; R 4 represents an alkylene group having 1 to 5 carbon atoms, such as methylene, ethylene, propylene, butylene, pentylene.

[0095] In a more specific embodiment, the ether compound used in the present invention is one or more selected from dimethyl ether, methyl ethyl ether, diethyl ether, ethyl propyl ether, dipropyl ether, dibutyl ether, methyl propyl ether, methyl butyl ether, methyl isobutyl ether, methyl tert-butyl ether, methyl isopentyl ether, methyl tert-pentyl ether, methyl cyclopentyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane.

[0096] In a preferred embodiment, the ether compound used in the present invention is one or more selected from ethyl ether, dipropyl ether, methyl cyclopentyl ether, methyl tert-amyl ether, ethylene glycol dimethyl ether, and tetrahydrofuran.

[0097] In a more preferred embodiment, the ether compound used in the present invention is one or more selected from ethyl ether and methyl cyclopentyl ether.

[0098] The solubility parameters and boiling points of some of the above-mentioned ether solvents are shown in Table 2.

[0099] Table 2

[0100]

[0101] In one embodiment, the solvent consists of an ether compound. The above-mentioned ether compounds and their preferred compounds can be used alone or in combination of 1, 2, 3 or more.

[0102] In other embodiments, the solvent further comprises one or more compounds selected from aromatic hydrocarbons, alkanes, esters, and ketones in addition to the ether compound. Examples of aromatic hydrocarbons include, but are not limited to, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, cumene, and diethylbenzene; examples of alkanes include, but are not limited to, n-hexane, cyclohexane, n-heptane, octane, isooctane, and isopentane; examples of esters include, but are not limited to, ethyl acetate, methyl acetate, n-butyl acetate, amyl acetate, isoamyl acetate, ethyl propionate, ethyl butyrate, ethyl lactate, ethyl formate, ethyl pelargonate, ethyl cinnamate, butyl cinnamate, ethyl caproate, ethyl phosphate, and diethyl phthalate; examples of ketones include, but are not limited to, acetone, butanone, and methyl isobutyl ketone. Among them, esters and ketones are preferred, and acetone, ethyl acetate, and isoamyl acetate are more preferred.

[0103] In the embodiment using a mixed solvent, the content of the ether compound in the solvent is 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and even more preferably 50% by mass or more. The higher the content of the ether compound, the more beneficial it is to the separation and recycling of the solvent.

[0104] In a specific embodiment, the self-stabilizing precipitation polymerization method of the present invention comprises the following steps:

[0105] Dissolve an electron-withdrawing monomer, an olefin monomer, and an initiator in the solvent and carry out a polymerization reaction.

[0106] In one embodiment, dissolve the electron-withdrawing monomer and the initiator in the solvent, and then add the olefin monomer to dissolve it.

[0107] In one embodiment, the polymerization reaction is initiated by heating the reaction system to the temperature of the polymerization reaction.

[0108] In one embodiment, the electron-withdrawing monomer is one or more selected from maleic anhydride, maleimide, itaconic anhydride, and their derivatives. Preferably, the electron-withdrawing monomer is one or more selected from maleic anhydride, itaconic anhydride, maleimide, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-(1-naphthyl)maleimide.

[0109] In one embodiment, the olefin monomer is one or more selected from linear olefins or cyclic olefins having 2 to 15 carbon atoms, aromatic olefins, conjugated dienes, and their derivatives.

[0110] Among them, the linear olefin can be straight-chain or branched-chain, preferably an α-olefin. Examples of the linear olefin and its derivatives include, but are not limited to, ethylene, propylene, 1-butene, isobutene, 1-pentene, (trans-, cis-)2-pentene, 2-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-nonene, 1-decene, 3-methyl-1-butene, 2-methyl-1-butene, 2-methyl-2-butene, 1,4-hexadiene, 1,6-hexadiene, ethylidene norbornene, etc. These olefins can be optionally mono-substituted or multi-substituted by halogen, and the halogen substituent can be fluorine, chlorine, or bromine, such as vinyl chloride, allyl chloride, etc.

[0111] The cyclic olefin can be a cyclic mono-olefin or poly-olefin. Examples of the cyclic olefin and its derivatives include, but are not limited to, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, dicyclopentadiene and its dimer, etc. These olefins can be optionally mono-substituted or multi-substituted by halogen, and the halogen substituent can be fluorine, chlorine, or bromine.

[0112] Examples of the aromatic olefin and its derivatives include, but are not limited to, optionally substituted styrene and optionally substituted indene, such as styrene, α-methylstyrene, vinyltoluene, methylvinylbenzene, dimethylvinylbenzene, ethylvinylbenzene, methyl-α-methylstyrene, divinylbenzene, methallylbenzene, indene, methylindene, dimethylindene, etc.

[0113] Among them, examples of the conjugated diene and its derivatives include, but are not limited to, optionally substituted butadiene, isoprene, cyclopentadiene, 1,3-pentadiene, 1,3-hexadiene, and 2,4-hexadiene, etc., where the substituents are independently one or more selected from halogen, C1-C10 alkyl, C1-C10 alkoxy, and phenyl.

[0114] More specifically, the conjugated diene may be butadiene, isoprene, (trans-, cis-)1,3-pentadiene, 2-chloro-1,3-butadiene, 2,3-dichlorobutadiene, 2,3-dimethylbutadiene, piperylene, 2,4-hexadiene, 2-methyl-1,3-pentadiene, 2-ethyl-1,3-butadiene, 2-propyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-methyl-1,3-hexadiene, 1-methoxy-1,3-butadiene, methylcyclopentadiene, dimethylcyclopentadiene, etc.

[0115] In addition, in the method of the present invention, there is no particular limitation on the source of the olefin monomer. For example, at least one of petroleum fractions containing the above olefin monomers (such as C4, C5, and C9 fractions), ethylene tar, C4+ by-product fractions from methanol to olefins, coal tar (such as dephenolized carbolic oil), and crude gasoline (such as gasoline before etherification) can be used as the raw material of the olefin monomer.

[0116] In one embodiment, the molar ratio of the electron-withdrawing monomer to the olefin is (0.1 to 2):1, preferably (0.5 to 1.5):1.

[0117] In one embodiment, the total mass concentration of the electron-withdrawing monomer and the olefin monomer in the reaction system is 0.1 to 50%, preferably 10 to 30%.

[0118] In this specification, the "reaction system" refers to a system composed of an electron-withdrawing monomer, an olefin monomer, an initiator, and a solvent.

[0119] In one embodiment, the initiator is one or more selected from peroxide initiators and azo compounds. The peroxide initiator is preferably benzoyl peroxide, diisopropylbenzene peroxide, ditert-butyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, and the azo compound is preferably azobisisobutyronitrile and azobisisoheptonitrile.

[0120] In one embodiment, the mass concentration of the initiator in the reaction system is 0.04 to 0.5%.

[0121] In one embodiment, the temperature of the polymerization reaction is 40 - 120 °C, preferably 50 - 100 °C;

[0122] In one embodiment, the polymerization reaction time is 0.01 to 24 hours, preferably 1 to 12 hours, more preferably 2 to 10 hours;

[0123] In one embodiment, the polymerization reaction is carried out in an inert gas atmosphere, for example, in an atmosphere of nitrogen or argon.

[0124] Based on the characteristics of the self-stable precipitation polymerization method itself, the reaction medium has good solubility for electron-withdrawing monomers and initiators, and is miscible with olefin monomers to ensure a homogeneous system before the reaction. However, the reaction medium cannot dissolve the resulting copolymer. When the polymer molecular chain reaches a certain critical length, it precipitates out of the reaction medium. However, the precipitated polymer does not precipitate in the form of powder or lumps as in precipitation polymerization, but stably suspends in the reaction medium in the form of microspheres or particles, forming a stable dispersion system similar to polymer emulsion.

[0125] In a more specific embodiment, the self-stable precipitation polymerization method of the present invention further comprises the following steps:

[0126] After the polymerization reaction, the reaction system is subjected to solid-liquid separation, and optionally the separated copolymer is dried.

[0127] Among them, the solid-liquid separation can be carried out by known methods, such as filtration, centrifugation, evaporation of solvents and other methods. Due to the use of low-boiling ether solvents in the self-stable precipitation polymerization method of the present invention, the solvent embedded in the copolymer obtained by solid-liquid separation is less, and the surface of the polymer microspheres is clean.

[0128] Drying can be carried out by methods known in the art, such as the method of evaporating the residual dissolution by heating. The drying temperature can be 40-150 °C, such as 40-100 °C, and the drying time can be 1-48 hours, such as 4-40 hours or 8-30 hours.

[0129] The present invention also correspondingly relates to copolymer microspheres obtained by the method of the present invention, with an average particle size of 0.1-10 μm, preferably 0.2-8 μm, more preferably 0.3-5 μm, and further preferably 0.4-3 μm, and the particle size distribution coefficient is 1.001-1.2, preferably 1.003-1.15, more preferably 1.005-1.1, such as 1.006-1.06.

[0130] In the copolymer microspheres obtained by the method of the present invention, the content of the residual solvent is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less, and even 1% by mass or less.

[0131] In one embodiment, the number-average molecular weight of the polymer measured by gel permeation chromatography can be 1,000-500,000, such as 5,000-300,000.

[0132] Examples

[0133] In the following examples, C4, C5, and C9 used are the C4, C5, and C9 components during the production of ethylene by naphtha cracking. C4, C5, C9, dephenolized phenol oil, and gasoline before etherification have the compositions shown in Tables 3 to 7 below:

[0134] Table 3 Composition of C4 Component

[0135] Component (Volume fraction) (%) Isobutane 30.82 n-Butane 15.18 Trans-2-Butene 14.57 1-Butene 11.44 Isobutene 15.75 Cis-2-Butene 10.93 Total olefins 52.79

[0136] Table 4 Composition of C5 Component

[0137] Component Mole content % Butadiene 0.37 3-Methyl-1-butene 0.60 Isopentane 8.49 2-Butyne 1.28 1-Pentene 3.51 2-Methyl-1-butene 4.76 n-Pentane 11.90 Isoprene 21.71 (Trans) 2-Pentene 2.17 (Cis) 2-Pentene 1.37 2-Methyl-2-butene 2.28 (Trans) 1,3-Pentadiene 9.90 (Cis) 1,3-Pentadiene 9.10 Cyclopentene 4.11 Cyclopentane 1.33 Isooctane 0.31 Cyclopentene-cyclopentadiene 0.48 Dicyclopentadiene 16.34 Polymerizable component 73.16

[0138] Table 5 Composition of C9 Component

[0139] Component Mole fraction % Cyclopentadiene 3.58 Methylcyclopentadiene 0.97 Toluene 0.32 Allylbenzene 1.26 Propylbenzene 0.70 Methylethylbenzene 3.66 Mesitylene 1.18 α-Methylstyrene 1.67 Methylethylbenzene 1.30 Methylvinylbenzene 19.59 Cyclopentene-cyclopentadiene 0.46 Methylvinylbenzene 3.66 Dicyclopentadiene 21.13 Indene 17.44 Diethylbenzene 0.48 Dimethylethylbenzene 0.55 Ethylvinylbenzene 0.75 Dimethylethylbenzene 1.88 Dimethylcyclopentadiene 10.24 Divinylbenzene 0.63 Dimethylethylbenzene 0.23 Methyl-α-methylstyrene 0.48 Methallylbenzene 0.25 Dihydronaphthalene 3.72 Methylindene 1.20 Naphthalene 1.88 2-Hydroxypropylbenzene 0.63 Total 99.80 Polymerizable component 86.11

[0140] Table 6 Composition of Dephenolized Phenol Oil

[0141] Composition Mass fraction % Styrene 2 α-Methylstyrene 4 Vinyltoluene 20 DCPD and co-dimers 6 Indene 20 Methylindene 5 Naphthalene 5 Other non-reactive aromatic compounds 38

[0142] Table 7 Composition of Gasoline before Etherification

[0143] Carbon number Naphthenes n-Alkanes i-Alkanes Olefins Aromatics Total 2 0 0 0 0 0 0 3 0 0.02 0 0.04 0 0.06 4 0 1.06 0.49 3.41 0 4.96 5 0.73 9.71 36.57 37.64 0 84.65 6 0.23 0.41 7.34 2.13 0.15 10.26 7 0 0 0 0.06 0 0.06 Total 0.96 11.2 44.4 43.28 0.15 99.99

[0144] Example 1

[0145] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C5 was added to the system for dissolution. The mass ratio of C5 to maleic anhydride was 1:0.75, where C5 was 10 g, maleic anhydride was 7.5 g, azobisisobutyronitrile was 0.75 g, and the medium was 100 ml of diethyl ether. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C5 copolymer microspheres. After centrifugal separation and vacuum drying at 70 °C for 24 h, white solid maleic anhydride and C5 copolymer microspheres were obtained. TGA tests were carried out, and the results were as Figure 9 shown, Figure 9 showing that there was a small amount of solvent in the dried microspheres, and it was estimated that the residual solvent was less than 1% of the total mass of the dried product.

[0146] Example 2

[0147] Under the condition of nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C5 was added and dissolved in the system. The mass ratio of C5 to maleic anhydride was 1:0.75, where C5 was 10 g, maleic anhydride was 7.5 g, azobisisobutyronitrile was 0.75 g, and the medium was methyl tert-amyl ether:acetone = 1:9, with a total of 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C5 copolymer microspheres, and then after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and C5 copolymer microspheres in the form of white solids were obtained.

[0148] Example 3

[0149] Under the condition of nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C5 was added and dissolved in the system. The mass ratio of C5 to maleic anhydride was 1:0.75, where C5 was 10 g, maleic anhydride was 7.5 g, azobisisobutyronitrile was 0.75 g, and the medium was cyclopentyl methyl ether at 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C5 copolymer microspheres, and then after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and C5 copolymer microspheres in the form of white solids were obtained.

[0150] Example 4

[0151] Under the condition of nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C5 was added and dissolved in the system. The mass ratio of C5 to maleic anhydride was 1:0.75, where C5 was 10 g, maleic anhydride was 7.5 g, azobisisobutyronitrile was 0.75 g, and the medium was ethylene glycol diethyl ether at 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C5 copolymer microspheres, and then after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and C5 copolymer microspheres in the form of white solids were obtained.

[0152] Example 5

[0153] Under the condition of nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C9 was added and dissolved in the system. The mass ratio of C9 to maleic anhydride was 1:0.5, where C9 was 10 g, maleic anhydride was 5 g, azobisisobutyronitrile was 0.5 g, and the medium was ether at 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C9 copolymer microspheres, and then after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and C9 copolymer microspheres in the form of white solids were obtained. TGA tests were carried out, and the results are as Figure 10 shown, Figure 10It is shown that there is a small amount of solvent in the microspheres after drying, and it is estimated that the residual solvent is less than 1% of the total mass of the dried product.

[0154] Example 6

[0155] Under the condition of nitrogen protection, monomer maleic anhydride and initiator benzoyl peroxide were added to the medium and fully dissolved, and then C9 was added and dissolved in the system. The mass ratio of C9 to maleic anhydride was 1:0.5, where C9 was 10 g, maleic anhydride was 5 g, benzoyl peroxide was 0.5 g, and the medium was cyclopentyl methyl ether:acetone = 1:9, totaling 100 ml. Water bath heating was used, and the reaction was carried out at 80 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C9 copolymer microspheres, which was then centrifuged and dried in vacuo at 70 °C for 24 h to obtain maleic anhydride and C9 copolymer microspheres in the form of white solids.

[0156] Example 7

[0157] Under the condition of nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and fully dissolved, and then C4 was added and dissolved in the system. The mass ratio of C4 to maleic anhydride was 1:0.3, where C4 was 10 g, maleic anhydride was 3 g, azobisisobutyronitrile was 0.1 g, and the medium was 100 ml of cyclopentyl methyl ether. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C4 copolymer microspheres, which was then centrifuged and dried in vacuo at 70 °C for 24 h to obtain maleic anhydride and C4 copolymer microspheres in the form of white solids.

[0158] Example 8

[0159] Under the condition of nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and fully dissolved, and then butadiene was added and dissolved in the system. The mass ratio of butadiene to maleic anhydride was 1:1, where butadiene was 5 g, maleic anhydride was 5 g, and azobisisobutyronitrile was 0.5 g. The medium was a mixture of 50 ml each of tetrahydrofuran and isoamyl acetate. Water bath heating was used, and the reaction was carried out at 80 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and butadiene copolymer microspheres, which was then centrifuged and dried in vacuo at 70 °C for 24 h to obtain maleic anhydride and butadiene copolymer microsphere solids in the form of white solids.

[0160] Example 9

[0161] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then dephenolized phenol oil was added to the system for dissolution. The mass ratio of dephenolized phenol oil to maleic anhydride was 1:0.5, where the dephenolized phenol oil was 10 g, maleic anhydride was 5 g, azobisisobutyronitrile was 0.5 g, and the medium ether was 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and butadiene copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and butadiene copolymer microspheres in the form of white solids were obtained.

[0162] Example 10

[0163] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then gasoline before etherification was added to the system for dissolution. The mass ratio of gasoline before etherification to maleic anhydride was 1:0.75, where the gasoline before etherification was 10 g, maleic anhydride was 7.5 g, azobisisobutyronitrile was 0.5 g, and the medium ether was 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and gasoline before etherification copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and gasoline before etherification copolymer microspheres in the form of white solids were obtained.

[0164] Example 11

[0165] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then propylene was added to the system for dissolution. The mass ratio of propylene to maleic anhydride was 0.5:1, where propylene was 5 g, maleic anhydride was 10 g, azobisisobutyronitrile was 0.2 g, and the medium cyclopentyl methyl ether was 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and propylene copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and propylene copolymer microspheres in the form of white solids were obtained.

[0166] Example 12

[0167] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then propylene and C4 were added to the system for dissolution. The mass ratio of propylene, C4 to maleic anhydride was 0.2:1:1, where propylene was 2 g, C4 was 10 g, maleic anhydride was 10 g, azobisisobutyronitrile was 0.2 g, and the medium cyclopentyl methyl ether was 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride, propylene and C4 terpolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride, propylene and C4 terpolymer microspheres in the form of white solids were obtained.

[0168] Example 13

[0169] Under the condition of nitrogen protection, the monomer maleic anhydride and the initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then ethylene was added and dissolved in the system. The mass ratio of ethylene to maleic anhydride was 0.3:1, where ethylene was 3 g, maleic anhydride was 10 g, azobisisobutyronitrile was 0.3 g, and the medium cyclopentyl methyl ether was 100 ml. Water bath heating was adopted, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and ethylene copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and ethylene copolymer microspheres in the form of white solids were obtained.

[0170] Example 14

[0171] Under the condition of nitrogen protection, the monomer maleic anhydride and the initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then styrene was added and dissolved in the system. The mass ratio of styrene to maleic anhydride was 1:1, where styrene was 10 g, maleic anhydride was 10 g, azobisisobutyronitrile was 0.2 g, and the medium cyclopentyl methyl ether was 100 ml. Water bath heating was adopted, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and styrene copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and styrene copolymer microspheres in the form of white solids were obtained. TGA test was carried out, and the results were as Figure 11 shown, Figure 11 showing that there was a small amount of solvent in the dried microspheres, and it was estimated that the solvent accounted for about 5% of the total mass of the dried product.

[0172] Example 15

[0173] Under the condition of nitrogen protection, the monomer maleic anhydride and the initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then isobutene was added and dissolved in the system. The mass ratio of isobutene to maleic anhydride was 0.6:1, where isobutene was 6 g, maleic anhydride was 10 g, azobisisobutyronitrile was 0.2 g, and the medium cyclopentyl methyl ether was 100 ml. Water bath heating was adopted, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and isobutene copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and isobutene copolymer microspheres in the form of white solids were obtained.

[0174] Example 16

[0175] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then indene was added to the system for dissolution. The mass ratio of indene to maleic anhydride was 1:1, with 10 g of indene, 10 g of maleic anhydride, 0.2 g of azobisisobutyronitrile, and 100 ml of medium cyclopentyl methyl ether. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and indene copolymer microspheres. Then, after centrifugal separation and vacuum drying at 70 °C for 24 h, maleic anhydride and indene copolymer microspheres in the form of white solids were obtained.

[0176] Comparative Example 1

[0177] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C5 was added to the system for dissolution. The mass ratio of C5 to maleic anhydride was 1:1, with 10 g of C5, 10 g of maleic anhydride, and 0.6 g of azobisisobutyronitrile. The medium was 100 ml of isoamyl acetate. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C5 copolymer microspheres. Then, after centrifugal separation and washing with petroleum ether and vacuum drying at 80 °C for 72 h, maleic anhydride and C5 copolymer microspheres in the form of white solids were obtained. TGA tests were carried out, and the results were as Figure 12 shown, Figure 12 showing that there were still a large amount of solvents in the dried microspheres, and it was estimated that the solvents accounted for about 30% of the total mass of the dried product.

[0178] Comparative Example 2

[0179] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly, and then C9 was added to the system for dissolution. The mass ratio of C9 to maleic anhydride was 2:1, with 20 g of C5, 10 g of maleic anhydride, 0.9 g of azobisisobutyronitrile, and 100 ml of medium isoamyl acetate. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and C9 copolymer microspheres. Then, after centrifugal separation and washing with petroleum ether and vacuum drying at 80 °C for 72 h, maleic anhydride and C9 copolymer microspheres in the form of white solids were obtained. TGA tests were carried out, and the results were as Figure 13 shown, Figure 13 showing that there were still a large amount of solvents in the dried microspheres, and it was estimated that the solvents accounted for about 30% of the total mass of the dried product.

[0180] Comparative Example 3

[0181] Under nitrogen protection, monomer maleic anhydride and initiator azobisisobutyronitrile were added to the medium and dissolved thoroughly. Then, styrene was added and dissolved in the system. The mass ratio of styrene to maleic anhydride was 1:1, where styrene was 10 g, maleic anhydride was 10 g, azobisisobutyronitrile was 0.2 g, and the medium isopentyl acetate was 100 ml. Water bath heating was used, and the reaction was carried out at 70 °C for 6 hours in a closed container to obtain a dispersion system of maleic anhydride and styrene copolymer microspheres. Then, it was centrifuged, washed with petroleum ether, and dried in vacuum at 80 °C for 72 h to obtain maleic anhydride and styrene copolymer microspheres in the form of white solids. TGA tests were carried out, and the results are as Figure 14 shown, Figure 14 indicating that there are still a large amount of solvents in the dried microspheres. It is estimated that the solvents account for about 30% of the total mass of the dried product.

[0182] <Evaluation>

[0183] TGA analysis

[0184] TGA model: Netzsch TG 209F3 Nevio

[0185] Test method: The test was carried out by heating from 25 °C to 800 °C at a rate of 20 °C / min.

[0186] TGA analysis was carried out on the copolymer microspheres obtained in Example 1, 5, 14 and Comparative Examples 1-3, and the results are respectively as Figures 9 - 14 shown. It can be Figures 9 - 14 seen that the residual solvent amounts of the copolymer microspheres obtained using ether-containing solvents in Examples 1, 5, 14 are less, while the residual solvent amounts of the copolymer microspheres obtained using non-ether-containing solvents in Comparative Examples 1-3 are significantly higher.

[0187] SEM analysis

[0188] A small amount of the dried maleic anhydride copolymer was dispersed in an appropriate amount of polymerization solvent. After ultrasonic dispersion, the dispersion was dropped on a cover glass and air-dried naturally. The morphology of the maleic anhydride copolymer was observed by a field emission scanning electron microscope (manufactured by JEOL Ltd., model: JSM7401) to obtain SEM photos of the copolymer microspheres of Examples 1-6, 13 and Comparative Example 1, as Figures 1 - 8 shown.

[0189] From Figures 1 - 8 it can be seen that the microscopic morphologies of the copolymer microspheres of Examples 1-6, 13 and Comparative Example 1 are all particles with uniform particle sizes. Different solvent types have a certain influence on the microsphere morphology and particle size. Therefore, spherical particles or flower-shaped particles with different particle sizes can be obtained by using different solvent types, that is, the morphology and particle size of the particles can be regulated by selecting different solvents.

[0190] Particle size analysis

[0191] The particle sizes and their distribution data of the copolymer microspheres obtained in Examples 1 to 16 and Comparative Examples 1 to 3 were obtained by the following method:

[0192] First, the particle sizes and particle size distributions of the microspheres in the scanning electron microscope photos were measured using measurement statistical software, and the particle sizes and distributions of the measured microspheres could be obtained through calculation using Formula 2-4.

[0193]

[0194]

[0195] U = D w / D n Formula (4)

[0196] Where:

[0197] D n —— The number-average particle size of the polymer microspheres;

[0198] D w —— The weight-average particle size of the polymer microspheres:

[0199] D i —— The particle size of the i-th microsphere;

[0200] N —— The total number of microspheres;

[0201] U —— The dispersion coefficient of the microsphere particle sizes.

[0202] Molecular weight test

[0203] Using tetrahydrofuran as the eluent, sample solutions of the copolymer microspheres obtained in Examples 1 to 16 and Comparative Examples 1 to 3 with a precisely prepared concentration of 5 mg / mL were prepared, and the molecular weights of the copolymers were tested using a gel permeation chromatograph.

[0204] The various properties and evaluation results of the copolymer microspheres obtained in Examples 1 to 16 and Comparative Examples 1 to 3 are shown in Table 3. Among them, the copolymer microspheres of Examples 1 to 6, 8, 10 and Comparative Examples 1 to 2 were internally crosslinked and could not be completely dissolved in THF, so molecular weight data were not measured.

[0205] Table 3

[0206]

[0207] As can be seen from Table 3, different types of olefins can achieve self-stabilized precipitation polymerization in ether solvents, and microspheres with particle sizes ranging from 0.6 to 2.142 μm can be obtained. The molecular weight and yield of the polymerization products obtained using ether solvents are roughly the same as those obtained using ester solvents, indicating that ether solvents are suitable for self-stabilized precipitation polymerization.

[0208] Industrial applicability

[0209] The method of the present invention can be widely used in the industrial preparation of copolymer microspheres.

Claims

1. A self-stabilizing precipitation polymerization method, characterized in that, a solvent containing an ether compound is used as the polymerization reaction medium, wherein the boiling point of the ether compound is below 145 °C; the self-stabilizing precipitation polymerization method comprises the following steps: dissolving an electron-withdrawing monomer, an olefin monomer and an initiator in the solvent for polymerization reaction; wherein, the electron-withdrawing monomer is one or more selected from maleic anhydride, itaconic anhydride, maleimide, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-(1-naphthyl)maleimide; the olefin monomer is one or more selected from linear olefins or cyclic olefins having 2 to 15 carbon atoms, aromatic olefins, conjugated dienes and their derivatives; the ether compound is one or more selected from dipropyl ether, dibutyl ether, methyl butyl ether, methyl isobutyl ether, methyl tert-butyl ether, methyl isoamyl ether, methyl tert-amyl ether, methyl cyclopentyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether; the molar ratio of the electron-withdrawing monomer to the olefin monomer is (0.1 - 2):1; the total mass concentration of the electron-withdrawing monomer and the olefin monomer in the reaction system is 0.1 - 50%; the reaction system refers to the system composed of the electron-withdrawing monomer, the olefin monomer, the initiator and the solvent.

2. The self-stabilizing precipitation polymerization method according to claim 1, characterized in that, the ether compound is one or more selected from methyl cyclopentyl ether, methyl tert-amyl ether, methyl tert-butyl ether, ethylene glycol dimethyl ether.

3. The self-stabilizing precipitation polymerization method according to claim 2, characterized in that, the ether compound is one or two selected from methyl tert-amyl ether and methyl cyclopentyl ether.

4. The self-stabilizing precipitation polymerization method according to claim 1 or 2, characterized in that, the solvent further contains one or more compounds selected from aromatic hydrocarbons, alkanes, esters, and ketones, and the content of the ether compound in the solvent is 10% by mass or more.

5. The self-stabilizing precipitation polymerization method according to claim 1 or 2, characterized in that, the solvent consists of the ether compound.

6. The self-stabilizing precipitation polymerization method according to claim 1 or 2, characterized in that, the olefin monomer is derived from a raw material selected from at least one of petroleum fractions, ethylene tar, C4+ by-product fractions from methanol-to-olefins, coal tar, and crude gasoline; the initiator is one or more selected from peroxide initiators and azo compounds.

7. The self-stabilizing precipitation polymerization method according to claim 6, characterized in that, the petroleum fraction is selected from C4, C5, and C9 fractions; the coal tar is dephenolized phenol oil; the crude gasoline is pre-etherification gasoline.

8. The self-stabilizing precipitation polymerization method according to claim 6, characterized in that, the peroxide initiator is one or more selected from benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, and the azo compound is one or two selected from azobisisobutyronitrile and azobisisoheptonitrile.

9. The self-stabilized precipitation polymerization method according to claim 1 or 2, characterized in that, the mass concentration of the initiator in the reaction system is 0.04 to 0.5%.

10. The self-stabilized precipitation polymerization method according to claim 9, characterized in that, the molar ratio of the electron-withdrawing monomer to the olefin monomer is (0.5 to 1.5):1; the total mass concentration of the electron-withdrawing monomer and the olefin monomer in the reaction system is 10 to 30%.

11. The self-stabilized precipitation polymerization method according to claim 1 or 2, characterized in that, the temperature of the polymerization reaction is 40 to 120 °C; the polymerization reaction time is 0.01 to 24 hours; the polymerization reaction is carried out in an inert gas atmosphere.

12. The self-stabilized precipitation polymerization method according to claim 1 or 2, characterized in that, it further comprises the following steps: after the polymerization reaction, the reaction system is subjected to solid-liquid separation, and optionally the separated copolymer is dried.

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