Crosslinked ethylene-propylene copolymer and preparation method and application thereof
阅读说明：本技术 一种交联乙丙共聚物及其制备方法和应用 (Crosslinked ethylene-propylene copolymer and preparation method and application thereof ) 是由 赵松美 董金勇 秦亚伟 刘洋 于 2018-07-20 设计创作，主要内容包括：本发明涉及一种交联乙丙共聚物及其制备方法和应用。该乙丙交联共聚物通过将乙烯、丙烯和二烯单体混合后在催化剂和助催化剂的存在下进行聚合反应制备。通过该方法制备的交联乙丙共聚物具有支化或交联结构,弹性较大,耐蠕变性能和回复性能得到提高,且具有剪切变稀行为,可在高温下熔融,降温后成型,适用于3D打印。该制备方法成本低廉,实施简便,便于规模化工业化生产。(The invention relates to a cross-linked ethylene-propylene copolymer, a preparation method and application thereof. The ethylene-propylene cross-linked copolymer is prepared by mixing ethylene, propylene and diene monomers and then carrying out polymerization reaction in the presence of a catalyst and a cocatalyst. The cross-linked ethylene-propylene copolymer prepared by the method has a branched or cross-linked structure, is high in elasticity, has improved creep resistance and recovery performance, has a shear thinning behavior, can be melted at a high temperature, is formed after being cooled, and is suitable for 3D printing. The preparation method has low cost and simple and convenient implementation, and is convenient for large-scale industrial production.)
1. A process for preparing a crosslinked ethylene-propylene copolymer, comprising: ethylene, propylene and diene monomers are mixed and then polymerized in the presence of a catalyst and a cocatalyst.
2. The process of claim 1, wherein the diene monomer is a bis α -olefin.
3. The method according to claim 1, wherein the diene monomer is at least one of compounds represented by general structural formulas (1) to (4);
wherein n in formula (1) is an integer greater than 4, and n in formula (2) and formula (3)1And n2Are all integers greater than 1.
4. The method of claim 1, wherein the diene monomer is at least one of 1, 9-decadiene, 1, 7-octadiene, 1, 5-hexadiene, 4- (3-butenyl) styrene, divinylbenzene isomers, or 1, 2-bis (4-vinylphenyl) ethane.
5. The process according to any of claims 1 to 4, wherein the catalyst comprises TiCl4、MgCl2And an internal electron donor and/or an external electron donor; the cocatalyst is an organic aluminum compound, preferably, the organic aluminum compound is at least one selected from triethyl aluminum, triisobutyl aluminum, tributyl aluminum and diethyl aluminum dichloride.
6. The process according to claim 1, wherein the amount of propylene is from 0.95 to 1.05mol, the amount of diene monomer is from 10 to 500mmol, the amount of catalyst is from 24 to 26mg and the amount of cocatalyst is from 1.6 to 1.8mmol per mole of ethylene.
7. The method according to claim 1 or 6, wherein the cocatalyst is introduced into the polymerization system in the form of a cocatalyst solution, and the solvent is used in an amount such that the concentration of the cocatalyst in the cocatalyst solution is 1.6 to 1.8 mol/L;
preferably, the solvent in the cocatalyst solution is selected from at least one of hexane, heptane, toluene and xylene.
8. The method of claim 1, wherein the solution polymerization is by simultaneous in situ polymerization;
preferably, the conditions of the solution polymerization reaction include: the temperature is 60-65 deg.C, the pressure is 0.38-0.42MPa, and the time is 15-30 min.
9. A crosslinked ethylene-propylene copolymer prepared by the process of any one of claims 1-8.
10. Use of a crosslinked ethylene-propylene copolymer according to claim 9 for 3D printing.
Technical Field
The invention relates to the field of 3D printing forming materials, in particular to a crosslinked ethylene-propylene copolymer and a preparation method and application thereof.
Background
3D printing technology is a form of additive manufacturing technology whose principle is to make objects by adding material to an object in layers. The 3D printing technology has realized a leap from a plan view to an entity, and a series of digital application technologies represented by it are even referred to as a third industrial revolution. The 3D printing technology mainly includes processes such as a stereolithography technology (SLA), a fused deposition modeling technology (FDM), a layered object manufacturing technology (LOM), a selective laser sintering technology (SLS), and the like. Wherein both FDM and SLS techniques use thermoplastics as the basic 3D printing material. However, the most serious problem and challenge facing 3D printing technology at present is that 3D printing molding materials are very rare. At present, 3D printing molding materials are mainly thermoplastic materials such as polylactic acid, nylon, polyethylene terephthalate, polybutylene terephthalate, Acrylonitrile Butadiene Styrene (ABS), and thermosetting materials such as epoxy. These materials are not only hard and brittle, but also require high printing conditions, and often fail to print minute structures with high definition. And thermosetting materials such as epoxy also face problems of recycling and difficult scrubbing.
Ethylene-propylene copolymer is an indispensable synthetic material in our lives, and is also one of elastomer materials with wider application. It has the features of low crystallinity, low glass transition temperature, transparency, softness, good luster, etc. and is used widely in cold resistant film, low temperature heat sealing film, transparent hollow container and other fields.
Ethylene-propylene copolymers are produced by mixing propylene and ethylene together, and have a random distribution of propylene and ethylene segments in the main chain of the polymer, and ethylene acts to prevent crystallization of the polymer, and when the ethylene content is up to 20% by weight, crystallization is difficult, and when the ethylene content is up to 30% by weight, it becomes completely amorphous. The random copolymer is characterized by low crystallinity, good transparency, increased impact strength, and reduced characteristic temperatures, such as melting temperature, glass transition temperature, brittle temperature, etc.
The ethylene-propylene copolymer mainly contains propylene, and a small amount of ethylene is added for copolymerization to obtain the ethylene-propylene random copolymer or the ethylene-propylene block copolymer, and the main characteristic is that when the ethylene content is low, the transparency is obviously improved. As the ethylene content increases, the stiffness and impact strength of the copolymer increases. The ethylene-propylene random copolymer has wide melting temperature range and good molding processability; the impact strength (particularly low-temperature impact) of the ethylene-propylene block copolymer increases with the increase in the block amount, but the moldability is poor. When 3D printing or printing is carried out, the ethylene-propylene random copolymer is difficult to meet the requirements of some related fields on the performances because of the characteristics of low toughness, poor creep resistance and the like of the elastomer.
Therefore, it is desirable to provide a method for improving the elasticity and creep resistance of ethylene-propylene random copolymers, which improves the elasticity and creep properties of ethylene-propylene copolymers and makes them suitable for 3D printing.
Disclosure of Invention
The invention aims to overcome the problems of low toughness and poor creep resistance of an ethylene-propylene random copolymer elastomer in the prior art, and provides a crosslinked ethylene-propylene copolymer and a preparation method thereof.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a crosslinked ethylene-propylene copolymer, the method comprising: ethylene, propylene and diene monomers are mixed and then polymerized in the presence of a catalyst and a cocatalyst.
In a second aspect, the present invention provides a crosslinked ethylene-propylene copolymer prepared by the above process.
The third aspect of the invention provides an application of the crosslinked ethylene-propylene copolymer prepared by the method in 3D printing.
By the technical scheme, the obtained crosslinked ethylene-propylene copolymer has a branched or crosslinked structure, is high in elasticity, and is improved in creep resistance and recovery performance. The cross-linked ethylene-propylene copolymer provided by the invention can be melted at high temperature, is formed after cooling, is suitable for 3D printing and forming, and can be recycled by 100%.
In addition, the preparation method of the crosslinked ethylene-propylene copolymer for 3D printing provided by the invention has the advantages of low cost, simple and convenient implementation and convenience for large-scale industrial production.
Drawings
FIG. 1 shows DSC scan curves (
fig. 2 is a dynamic shear rheological frequency scan plot of ethylene-propylene copolymer 1(EPR-1), ethylene-propylene copolymer 2(EPR-2), ethylene-propylene copolymer 3(EPR-3), ethylene-propylene copolymer 4(EPR-4) at a temperature of 70 ℃ (T70 ℃) and a temperature of 160 ℃ (T160 ℃);
fig. 3 is a creep-recovery curve of ethylene-propylene copolymer 1(EPR-1), ethylene-propylene copolymer 2(EPR-2), ethylene-propylene copolymer 3(EPR-3), ethylene-propylene copolymer 4(EPR-4) at a stress (σ) of 5Pa and 50Pa, at a temperature of 70 ℃ (T ═ 70 ℃) and at a temperature of 160 ℃ (T ═ 160 ℃);
fig. 4 is a creep-recovery curve of ethylene-propylene copolymer 4(EPR-4) at a temperature of 70 ℃ and 160 ℃ (T ═ 70 ℃ and 160 ℃), with stresses of 5Pa, 10Pa, and 50Pa (σ ═ 5,10,50 Pa);
fig. 5 is a capillary rheology test curve of ethylene-propylene copolymer 1(EPR-1), ethylene-propylene copolymer 2(EPR-2), ethylene-propylene copolymer 3(EPR-3), ethylene-propylene copolymer 4(EPR-4) at a temperature of 160 ℃ (T160 ℃);
fig. 6 is a schematic view of the extrudate shape of ethylene-propylene copolymer 4(EPR-4) at a temperature of 160 ℃ (T ═ 160 ℃).
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In a first aspect the present invention provides a process for the preparation of a crosslinked ethylene-propylene copolymer, which process comprises: ethylene, propylene and diene monomers are mixed and then polymerized in the presence of a catalyst and a cocatalyst.
According to the invention, the diene monomer is a key component for preparing the crosslinked ethylene-propylene copolymer, and the crosslinking and the stabilization of the ethylene-propylene copolymer are realized by adding the diene monomer. The diene monomer is typically an aliphatic or aromatic symmetric diene monomer. Preferably, the diene monomer is a bis-a-olefin having a strong coordination polymerization ability. More preferably, the diene monomer is at least one of compounds represented by the general structural formulas (1) to (4);
wherein n in formula (1) is an integer greater than 4, and n in formula (2) and formula (3)1And n2Are all integers greater than 1.
Most preferably, the diene monomer is at least one of 1, 9-decadiene, 1, 7-octadiene, 1, 5-hexadiene, 4- (3-butenyl) styrene, divinylbenzene isomers, or 1, 2-bis (4-vinylphenyl) ethane.
According to the invention, the catalyst can be any of the various conventional catalysts for the polymerization of ethylene and propylene, preferably the catalyst contains TiCl4、MgCl2And an internal electron donor and/or an external electron donor.
Wherein, TiCl4As active component of the catalyst, MgCl2Is a carrier because of different internal electron donors and MgCl2The coordination modes and positions of the carriers are different, the functions of the carriers are also obviously different, and an external electron donor can be selectively added in order to ensure that the catalyst can obtain a better catalyst effect.
Preferably, the internal electron donor is a diester or diether internal electron donor, such as 9,9- (methoxymethyl) fluorene (BMMF) or Diisobutylphthalate (DIBP).
According to the selection condition of the internal electron donor of the catalyst, if DIBP is selected, an external electron donor is added to assist the catalyst in catalyzing polymerization. Preferably, the external electron donor has a structural general formula of R4-nSi(OR')nWherein n is more than or equal to 1 and less than or equal to 3, and R' are respectively and independently selected from any one of alkyl, cycloalkyl and aryl. Preferably, the external electron donor is selected from at least one of dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, methyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane or methylcyclohexyldimethoxysilane.
According to the present invention, preferably, the cocatalyst is an organoaluminum compound. More preferably, the organoaluminum compound is at least one selected from the group consisting of triethylaluminum, triisobutylaluminum, tributylaluminum and dichlorodiethylaluminum. According to a preferred embodiment of the present invention, the cocatalyst is introduced into the polymerization system in the form of a cocatalyst solution in order to further improve the properties of the resulting polymer. The solvent in the initiator solution is an organic solvent not participating in the polymerization reaction, and preferably, the solvent is at least one selected from hexane, heptane, toluene, and xylene. That is, the cocatalyst is added after dilution with a solvent. Preferably, the solvent is used in an amount such that the concentration of the cocatalyst in the cocatalyst solution is 1.6-1.8 mol/L.
According to the present invention, each of the reaction raw materials can be commercially available without particular indication, and the amount of each raw material is not particularly limited, and preferably, propylene is used in an amount of 0.95 to 1.05mol per mol of ethylene.
Preferably, the diene monomer is used in an amount of 10 to 500mmol per mole of ethylene.
Preferably, the catalyst is used in an amount of 24 to 26mg per mole of ethylene.
Preferably, the cocatalyst is used in an amount of 1.6 to 1.8mmol per mole of ethylene.
According to the invention, the solution polymerization is preferably carried out in situ. The synchronous in-situ polymerization in the invention means that reaction monomers of ethylene, propylene, diene monomer, catalyst and cocatalyst are synchronously added into a reactor, and then the in-situ polymerization reaction is started.
According to a further preferred embodiment of the present invention, the conditions of the solution polymerization reaction include a temperature of 60 to 65 ℃, a pressure of 0.38 to 0.42MPa, and a time of 15 to 30 min.
In the present invention, the resulting product may be subjected to a post-treatment using various post-treatment methods conventionally used in the art. Methods of such post-processing include, but are not limited to: washing, filtering, drying, etc. The present invention is not described in detail herein, and the post-processing methods mentioned in the embodiments are only for illustrative purposes, and do not indicate that they are necessary operations, and those skilled in the art may substitute other conventional methods.
In a second aspect, the present invention provides a crosslinked ethylene-propylene copolymer prepared by the above process.
According to the present invention, the crosslinked ethylene-propylene copolymer prepared by the above method comprises an ethylene-propylene random copolymer and an ethylene-propylene copolymer having a crosslinked structure. The ethylene-propylene copolymer with a cross-linked structure is defined as a polymer formed by polymerization reaction of a diene monomer, ethylene and propylene, can be an ethylene-propylene copolymer with a branched or cross-linked structure and containing a diene monomer unit, and also comprises an ethylene-higher alpha-olefin binary or ethylene-higher alpha-olefin-propylene ternary random copolymer. Wherein the ethylene-propylene random copolymer accounts for a larger proportion, and the molar content of the ethylene-propylene random copolymer is preferably 0-99%, more preferably 1-95%, calculated according to the content of residual double bonds in a nuclear magnetic carbon spectrum.
The weight-average molecular weight of the cross-linked ethylene-propylene copolymer prepared by the invention is 9 multiplied by 104-1.2×105g/mol, polymer dispersity index is 8-10.
In a third aspect, the invention provides a use of the crosslinked ethylene-propylene copolymer prepared by the above method in 3D printing.
According to the invention, the cross-linked ethylene-propylene copolymer provided by the invention has good elasticity and creep property, can be melted at high temperature, can be molded after cooling, can be suitable for 3D printing molding, and can be recycled by 100%.
According to the invention, the cross-linked ethylene-propylene copolymer provided by the invention can be used for 3D printing and forming to construct a required structure and model, and can also be mixed with one or more other resins and/or one or more other fillers to be used for 3D printing and forming to construct a required structure and model.
According to the present invention, it is preferable that the other resin mixed with the cross-linked ethylene-propylene copolymer is at least one of polypropylene, polyethylene, polyhexene, polybutene, polymethacrylic resin, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyester, polyether, polysulfone, polyphenylene oxide, polyether ether ketone, polylactic acid, nylon, and acrylonitrile-butadiene-styrene.
Preferably, the filler mixed with the crosslinked ethylene-propylene copolymer is at least one of carbon nanotubes, graphene oxide, clay, boron nitride, silicon nitride and boron silicide.
The present invention will be described in detail below by way of examples.
In the following examples and preparations, various starting materials used were commercially available and the methods used were conventional ones unless otherwise specified. The pressures are gauge pressures.
In the following examples and comparative examples, molecular weight (weight average molecular weight M)w) And Polymer Dispersibility Index (PDI) were measured using a model PL-220 series high temperature Gel Permeation Chromatograph (GPC), Agilent corporation, USA, under the following test conditions: the test temperature was 150 ℃, the solvent was 1,2, 4-Trichlorobenzene (TCB), the flow rate of the mobile phase was 1.0mL/min, and polystyrene was used as a standard.
Preparation example
Preparation of the catalyst
150mL of TiCl was added to a 500mL reactor with a sand core filter at the bottom and mechanical stirring under a dry high purity nitrogen blanket4Cooling to-20 deg.C, adding 7.05g of MgCl on spherical support2And the reaction was carried out for 1 hour. The temperature was raised to 60 ℃ and 1.335g ofSlowly heating 9, 9-di (methoxymethyl) fluorene (BMMF) to 120 ℃, reacting for 2 hours, filtering, and filtering to remove TiCl4And (3) solution. 150mL of hot TiCl were then added4The reaction was carried out at 110 ℃ for 2 hours, and after cooling to 60 ℃, the product was washed with dried hexane to obtain a catalyst for polymerization. The particle shape is spherical particle under electron microscope observation, the diameter is 10-100 μm, and the specific surface area is 8.4m2(ii) in terms of/g. The mass percentage of Ti in the catalyst is 4.1 percent, and the mass percentage of the internal electron donor BMMF is 5.4 percent.
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