WO2024112040A1 - Method for preparing ethylene/alpha-olefin copolymer - Google Patents

Abstract

According to the present invention, provided is a method for preparing an ethylene/alpha-olefin copolymer, comprising: a primary polymerization step in which a reactant including a solvent, ethylene, and an olefin monomer, and a catalyst are supplied to a polymerization reactor so as to polymerize same; and a secondary polymerization step after the primary polymerization step, wherein the secondary polymerization step is performed at a temperature 10°C to 50°C higher than the polymerization temperature of the primary polymerization step.

Description

Method for producing ethylene-alpha-olefin copolymer

The present invention relates to a method for producing an ethylene-alpha-olefin copolymer and an ethylene-alpha-olefin copolymer produced by the method.

Recently, along with the expansion of the renewable energy market, the solar energy market is also growing explosively. Among them, olefin materials are widely used as encapsulation materials for solar panels.

Currently, the most widely used encapsulant is one made of EVA (ethylene vinyl acetate)-based material for attaching and encapsulating photovoltaic cells or photovoltaic arrays to ferroelectrics.

However, the EVA has poor adhesion to glass and other parts of the module, and accordingly, when the photovoltaic module is used for a long period of time, peeling between each layer of the module is easily caused, which reduces the efficiency of the module or causes moisture infiltration. There is a problem of corrosion caused by .

In addition, the encapsulants known to date have poor resistance to ultraviolet (UV) rays, etc., and when used for a long period of time, problems such as discoloration or discoloration or PID (Potential Induced Degradation) problems occur, which also reduces the efficiency of the module. In addition, encapsulants made of materials such as EVA have a problem in that stress is generated during curing, causing damage to the module.

To solve this problem, encapsulants manufactured using ethylene-alpha-olefin copolymers have recently been in the spotlight.

However, ethylene-alpha-olefin copolymers also have problems that need to be improved. One of them is cross-linking speed. Ethylene-alpha-olefin copolymer has a relatively slow cross-linking speed compared to EVA, so when the existing module manufacturing process is applied to ethylene-alpha-olefin copolymer products, cross-linking does not occur properly due to the slow cross-linking speed. As a result, problems with adhesion may occur. As a way to compensate for this, it has been proposed to mold at high temperature for a long time, but in this case, there is a risk of deformation such as yellowing or heat shrinkage occurring.

Therefore, there is a need to provide an ethylene-alpha-olefin copolymer in which crosslinking can occur as quickly as possible even at low temperatures.

[Prior art literature]

[Patent Document]

Korean Patent Publication No. 10-1998-0075880

The present invention is intended to solve the problems of the prior art as described above, and is an ethylene-alpha-olefin copolymer used as an encapsulant for solar cells, which can shorten the time required for the crosslinking process performed at high temperature and high pressure. -The purpose is to provide a method for producing alpha-olefin copolymers.

According to one embodiment of the present invention, it includes a first polymerization step of supplying reactants and a catalyst containing a solvent, ethylene, and olefin monomer to a polymerization reactor for polymerization, and a second polymerization step after the first polymerization step, and the second polymerization step includes: A method for producing an ethylene-alpha-olefin copolymer is provided, wherein the polymerization step is performed at a temperature 10° C. to 50° C. higher than the polymerization temperature of the first polymerization step.

According to another embodiment of the present invention, an ethylene-alpha-olefin copolymer prepared by the above production method is provided.

According to another embodiment of the present invention, a resin composition for solar cell encapsulation comprising an ethylene-alpha-olefin copolymer prepared by the above production method and a crosslinking agent is provided.

The polyethylene-alpha-olefin copolymer according to the present invention takes a shorter time to reach the same degree of cross-linking compared to the polymer resin used as a conventional solar encapsulation material, so the work time required to manufacture solar panels can be significantly shortened. .

Figure 1 schematically shows the polymerization process for producing ethylene-alpha-olefin copolymer by the production method of the present invention.

Figure 2 is a graph showing the results of TGIC analysis of the ethylene-alpha-olefin copolymer prepared according to Example 1.

Figure 3 is a graph showing the results of TGIC analysis of the ethylene-alpha-olefin copolymer prepared according to Comparative Example 1.

According to one embodiment of the present invention, it includes a first polymerization step of supplying reactants and a catalyst containing a solvent, ethylene, and olefin monomer to a polymerization reactor for polymerization, and a second polymerization step after the first polymerization step, and the second polymerization step includes: A method for producing an ethylene-alpha-olefin copolymer is provided, wherein the polymerization step is performed at a temperature 10° C. to 50° C. higher than the polymerization temperature of the first polymerization step.

More specifically, the catalyst includes at least one cocatalyst compound selected from the group consisting of a main catalyst compound represented by Formula 1 below and a compound represented by Formula 2 or 3 below, and the catalyst and reactants are supplied to a polymerization reactor for polymerization. It includes a step, wherein the reactants include a solvent, ethylene, and an olefin monomer, the polymerization step includes a first polymerization step and a second polymerization step, and the first polymerization step and the second polymerization step are performed at 10° C. to A method for producing an ethylene-alpha-olefin copolymer having a temperature difference of 50° C. is provided.

[Formula 1]

In Formula 1,

M is a group 4 transition metal;

Q ¹ and Q ² are each independently halogen, (C ₁ -C ₂₀ )alkyl, (C ₂ -C ₂₀ )alkenyl, (C ₂ -C ₂₀ )alkynyl, (C ₆ -C ₂₀ )aryl, ( C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl, (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl, (C ₁ -C ₂₀ )alkylamido, (C ₆ -C ₂₀ )arylamido or (C ₁ -C ₂₀ )alkylidene;

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently hydrogen; (C ₁ -C ₂₀ )alkyl with or without acetal, ketal or ether groups; (C ₂ -C ₂₀ )alkenyl with or without acetal, ketal or ether groups; (C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl with or without an acetal, ketal or ether group; (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl with or without an acetal, ketal or ether group; or (C ₁ -C ₂₀ )alkylsilyl with or without an acetal, ketal or ether group; R ¹ and R ² may be connected to each other to form a ring, R ³ and R ⁴ may be connected to each other to form a ring, and two or more of R ⁵ to R ¹⁰ may be connected to each other to form a ring. You can;

R ¹¹ , R ¹² and R ¹³ are each independently hydrogen; (C ₁ -C ₂₀ )alkyl with or without acetal, ketal or ether groups; (C ₂ -C ₂₀ )alkenyl with or without acetal, ketal or ether groups; (C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl with or without an acetal, ketal or ether group; (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl with or without an acetal, ketal or ether group; (C ₁ -C ₂₀ )alkylsilyl with or without acetal, ketal or ether groups; (C ₁ -C ₂₀ )alkoxy; or (C ₆ -C ₂₀ )aryloxy; R ¹¹ and R ¹² or R ¹² and R ¹³ may be connected to each other to form a ring.

[Formula 2]

[LH] ⁺ [Z(A) ₄ ] ^-

[Formula 3]

[L] ⁺ [Z(A) ₄ ] ^-

In Formula 2 and Formula 3, L is a neutral or cationic Lewis acid, Z is a Group 13 element, A is (C ₆ -C ₂₀ )aryl or (C ₁ -C ₂₀ )alkyl, and the (C ₆ -C ₂₀ )aryl or (C ₁ -C ₂₀ )alkyl is substituted with halogen, (C ₁ -C ₂₀ )hydrocarbyl, (C ₁ -C ₂₀ )alkoxy, or (C ₆ -C ₂₀ )aryloxy or It is not replaced.

The main catalyst compound represented by Formula 2 or 3 has strong electrophilicity and quickly dissociates Q ¹ and/or Q ² bonded to the central metal M of the main catalyst compound represented by Formula 1. At this time, the faster the dissociation of Q ¹ and/or Q ² occurs, the more the polymerization activity increases, and the longer the time for the central metal M to be stabilized, the closer M in the stabilized state is to the double bond contained in ethylene and alpha-olefin. As the coordination becomes longer, a high molecular weight ethylene-alpha-olefin copolymer can be obtained.

The transition metal compound represented by Formula 1 is a new compound in which the amido ligand and ortho-phenylene form a condensed ring, and the pentagonal pi-ligand bonded to the ortho-phenylene is fused by a thiophene heterocycle. Includes structural ligands. Accordingly, the transition metal compound has the advantage of having a higher ethylene-alpha-olefin copolymerization activity compared to the transition metal compound in which the thiophene hetero ring is not fused.

According to the present invention, in the compound represented by Formula 1, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ^{6 , R 7} , R ⁸ , R ⁹ , R ¹⁰ , R ^{11 ,} R ¹² and R ¹³ may each independently be substituted with a substituent including an acetal, ketal, or ether group. When substituted with such a substituent, it may be more advantageous for supporting the support on the surface of the carrier.

Additionally, in the compound represented by Formula 1, M is preferably titanium (Ti), zirconium (Zr), or hafnium (Hf).

Additionally, in the transition metal compound represented by Formula 1, Q ¹ and Q ² are each independently preferably halogen or (C ₁ -C ₂₀ )alkyl, and more preferably chlorine or methyl.

In addition, in the transition metal compound represented by Formula 1, R ¹ , R ² , R ³ , R ⁴ and R ⁵ may each independently be hydrogen or (C ₁ -C ₂₀ )alkyl, preferably Each may independently be hydrogen or methyl. More preferably, R ¹ , R ² , R ³ , R ⁴ and R ⁵ may each independently be hydrogen or methyl, provided that at least one of R ³ and R ⁴ is methyl and R ⁵ may be methyl. there is.

Additionally, in the transition metal compound represented by Formula 1, R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are each preferably hydrogen.

The transition metal compound represented by Formula 1 preferably contains the above substituents to control the electronic and steric environment around the metal.

Meanwhile, the transition metal compound represented by Formula 1 can be obtained from a precursor compound represented by Formula 4 below:

[Formula 4]

In Formula 4, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are each defined in Formula 1 above. It's like a bar.

Here, the precursor compound represented by Formula 4 is prepared by (i) reacting a tetrahydroquinoline derivative represented by Formula 5 with alkyl lithium and then adding carbon dioxide to prepare a compound represented by Formula 6; and (ii) reacting the compound represented by Formula 6 with alkyl lithium, then adding a compound represented by Formula 7 below and subjecting it to acid treatment.

[Formula 5]

[Formula 6]

[Formula 7]

In Formula 5, Formula 6 and Formula 7, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are Each is as defined in Formula 1 above.

However, in Formulas 5, 6 and 7, R ¹ , R ² , R ³ , R ⁴ and R ⁵ may each independently be hydrogen or (C ₁ -C ₂₀ )alkyl, preferably each It may independently be hydrogen or methyl. More preferably, R ¹ , R ² , R ³ , R ⁴ and R ⁵ may each independently be hydrogen or methyl, provided that at least one of R ³ and R ⁴ is methyl and R ⁵ may be methyl. there is. In addition, R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are each preferably hydrogen. Through this, the accessibility and reactivity of the starting material can be secured, and it is advantageous for controlling the electronic and steric environment of the transition metal compound of Formula 1 to be produced.

Step (i) is a reaction in which the tetrahydroquinoline derivative represented by Formula 5 is reacted with alkyl lithium and then converted to the compound represented by Formula 6 by adding carbon dioxide, according to a method described in a known literature. It can be performed (Tetrahedron Lett. 1985, 26, 5935; Tetrahedron 1986, 42, 2571; J.Chem.SC.Perkin Trans. 1989, 16.).

In addition, in step (ii), a deprotonation reaction is induced by reacting alkyl lithium with the compound represented by Formula 6 to produce an ortho-lithium compound, which is reacted with a compound represented by Formula 7 and treated with acid to produce the above. A transition metal compound precursor represented by Formula 4 can be obtained.

The reaction of producing an ortho-lithium compound by reacting alkyllithium with the compound represented by Formula 6 can be identified through known literature (Organometallics 2007, 27, 6685; Republic of Korea Patent Publication No. 2008-0065868). In the present invention, a transition metal compound precursor represented by Formula 7 can be obtained by reacting the compound represented by Formula 7 and treating it with acid.

Here, the compound represented by Formula 7 can be prepared through various known methods. Scheme 1 below shows one example, and not only can it be prepared in one step, but it also uses inexpensive starting materials, making it possible to easily and economically prepare the transition metal compound precursor of the present invention (J Organomet. Chem., 2005, 690, 4213).

[Scheme 1]

Meanwhile, various known methods can be used to synthesize the transition metal compound represented by Formula 1 from the precursor compound represented by Formula 4 obtained through the above method. By adding about 2 equivalents of alkyllithium to the precursor compound represented by Formula 4 to induce a deprotonation reaction, a dilithium compound of cyclopentadienyl anion and amide anion was prepared, and then (Q ¹ )(Q ² ) It can be manufactured by adding MCl ₂ to remove about 2 equivalents of LiCl.

In addition, the compound represented by Formula 2 is reacted with the M(NMe ₂ ) ₄ compound to remove about 2 equivalents of HNMe ₂ to obtain a transition metal compound represented by Formula 1 in which Q ¹ and Q ² are both NMe ₂ , The NMe ₂ ligand can be changed to a chlorine ligand by reacting Me ₃ SiCl or Me ₂ SiCl ₂ here.

The catalyst of the present invention includes a cocatalyst along with a transition metal compound represented by Formula 1 above. The cocatalyst serves to activate the transition metal compound and is a compound represented by Formula 2 or 3, and activates the main catalyst compound represented by Formula 1.

According to the present invention, in the cocatalyst compound represented by Formula 2, [LH] ⁺ is a dimethylanilinium cation, and [Z(A) ₄ ] ^- is [B(C ₆ F ₅ ) ₄ ] ^- It is desirable to be In addition, in the cocatalyst compound represented by Formula 3, [L] ⁺ is [(C ₆ H ₅ ) ₃ C] ⁺ , and [Z(A) ₄ ] ^- is [B(C ₆ F) ₅ ) ₄ ] ^- is preferred.

Here, the cocatalyst compound represented by Formula 2 is not particularly limited, but non-limiting examples include trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, and trimethylammonium tetrakis(pentafluorophenyl)borate. Phenyl)borate (Triethylammonium tetrakis(pentafluorophenyl)borate), Tripropylammonium tetrakis(pentafluorophenyl)borate), Tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate ( Ttri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate), Tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate), N,N-dimethyl Anilinium tetrakis(pentafluorophenyl)borate (N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate), N,N-dimethylanilinium n-butyltris(pentafluorophenyl)borate (N,N-dimethylanilinium n- butyltris(pentafluorophenyl)borate), N,N-dimethylanilinium benzyltris(pentafluorophenyl)borate), N,N-dimethylanilinium tetrakis(4-(t -Butyldimethylsilyl)-2,3,5,6-tetrafluorophenyl)borate (N,N-dimethylanilinium tetrakis(4-(t-butyldimethylsiiyl)-2,3,5 6-tetrafluorophenyl)borate), N, N-dimethylanilinium tetrakis(4-(t-triisopropylsilyl)-2,3,5,6-tetrafluorophenyl)borate (N,N-dimethylanilinium tetrakis(4-(triisopropysilyl)-2,3 ,5,6-tetrafluorophenyl)borate), N,N-dimethylanilinium pentafluorophenoxytris(pentafluorphenyl)borate), N,N-diethylanyl Linium tetrakis(pentafluorophenyl)borate (N,N-diethylanilinium tetrakis(pentafluorphenyl)borate), N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(pentafluorophenyl)borate(N, N-dimethyl-2,4,6-trimethylanilinium tetrakis(pentafluorophenyl)borate), N,N-dimethylammonium tetrakis(2,3,5,6-tetrafluorophenyl)borate (trimethylammonium tetrakis(2,3,4) ,6-tetrafluorophenyl)borate), N,N-diethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate (triethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate), tree Propylammonium tetrakis(2,3,4,6-tetrafluorophcnyl)borate, tri(n-butyl)ammonium tetrakis(2,3, 4,6-tetrafluorophenyl)borate (tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate), dimethyl(t-butyl)ammonium tetrakis(2,3,4,6) -Tetrafluorophenyl)borate (dimethyl(t-butyl)ammonium tetrakis (2,3,4,6-tetrafluorophenyl)borate), N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorate) N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate), N,N-diethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate (N,N-diethylanilinium tetrakis (2,3,4,6-tetrafluorophenyl)borate), N,N-dimethyl2,4,6-trimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl) ) It is preferable that it is at least one selected from the group consisting of borate (N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate) and dialkylammonium.

The dialkylammonium includes, but is not limited to, di-(i-propyl)ammonium tetrakis(pentafluorophenyl)borate, or dicyclohexylammonium tetrakis. (pentafluorophenyl)borate (dicyclohexylammonium tetrakis(pentafluorophenyl)borate), etc.

In addition, the cocatalyst compound represented by Formula 3 is not particularly limited, but as a non-limiting example, it is preferably at least one selected from the group consisting of trialkylphosphonium, dialkyloxonium, dialkylsulfonium, and carbonium salt. do.

The trialkylphosphonium includes, but is not limited to, triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(o-tolylphosphonium tetrakis(pentafluorophenyl)borate ( tri(o-tolylphosphonium tetrakis(pentafluorophenyl)borate), or tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate), etc. can be mentioned.

The dialkyloxonium includes, but is not limited to, diphenyloxonium tetrakis(pentafluorophenyl)borate, di(o-tolyl)oxonium tetrakis(pentafluorophenyl)borate, etc. (di(o-tolyl)oxonium tetrakis(pentafluororphenyl)borate), or di(2,6-dimethylphenyl oxonium tetrakis(pentafluorophenyl)borate) etc. can be mentioned.

The dialkylsulfonium includes, but is not limited to, diphenylsulfonium tetrakis(pentafluorophenyl)borate, di(o-tolyl)sulfonium tetrakis(pentafluorophenyl)borate, etc. (di(o-tolyl)sulfonium tetrakis(pentafluorophenyl)borate), or bis(2,6-dimethylphenyl)sulfonium tetrakis(pentafluorophenyl) borate), etc.

The carbonium salt includes, but is not limited to, tropylium tetrakis(pentafluorophenyl)borate and triphenylmethylcarbenium tetrakis(pentafluorophenyl)borate. borate), or benzene(diazonium)tetrakis(pentafluorophenyl)borate).

These cocatalyst compounds include trialkyl aluminum such as Trimethylaluminum, Triethylaluminum, Tributylaluminum, Trihexylaluminum, Trioctylaluminum, and Tridecylaluminum. It may further include.

Meanwhile, the amount of the co-catalyst compound added can be determined by considering the amount of the main catalyst compound added and the amount necessary to sufficiently activate the co-catalyst compound. According to the present invention, the co-catalyst compound may be included in a molar ratio of 1:1 to 100,000, preferably 1:1 to 10,000, and more preferably 1:1 to 5,000 with respect to the main catalyst compound. More specifically, the cocatalyst compound represented by Formula 2 or 3 is 1:1 to 100, preferably 1:1, relative to the main catalyst compound, a transition metal compound, for example, the main catalyst compound represented by Formula 1. It may be included in a molar ratio of 1 to 10, more preferably 1:1 to 4.

Meanwhile, the catalyst of the present invention including the main catalyst compound and the co-catalyst compound may further include a carrier.

Here, as the carrier, any carrier made of inorganic or organic materials used in the production of catalysts in the technical field to which the present invention pertains may be used without limitation.

According to one embodiment of the present invention, the carrier is SiO ₂ , Al ₂ O ₃ , MgO, MgCl ₂ , CaCl ₂ , ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO ₂ , SiO ₂ -Al ₂ O ₃ , SiO ₂ -MgO, SiO ₂ -TiO ₂ , SiO ₂ -V ₂ O ₅ , SiO ₂ -Cr ₂ O ₃ , SiO ₂ -TiO ₂ -MgO, bauxite, zeolite, starch ), cyclodextrin, or synthetic polymer.

Preferably, the carrier includes a hydroxy group on the surface, and is selected from the group consisting of silica (SiO ₂ ), silica-alumina (SiO ₂ -Al ₂ O ₃ ), and silica-magnesia (SiO ₂ -MgO). There may be more than one species.

Methods for supporting a catalyst containing the main catalyst compound and the co-catalyst compound on the carrier include directly supporting the main catalyst compound on a dehydrated carrier; A method of pretreating the carrier with the cocatalyst compound and then supporting the main catalyst compound; A method of supporting the main catalyst compound on the carrier and then post-treating it with the cocatalyst compound; A method of reacting the main catalyst compound with the co-catalyst compound and then adding the carrier for reaction may be used.

The solvent that can be used in the supporting method may be an aliphatic hydrocarbon-based solvent, an aromatic hydrocarbon-based solvent, a halogenated aliphatic hydrocarbon-based solvent, or a mixture thereof.

The aliphatic hydrocarbon-based solvent includes, but is not limited to, Pentane, Hexane, Heptane, Octane, Nonane, Decane, Undecane, or Dodecane ( Dodecane), etc.

Non-limiting examples of the aromatic hydrocarbon solvent include benzene, monochlorobenzene, dichlorobenzene, trichlorobenzene, or toluene.

Non-limiting examples of the halogenated aliphatic hydrocarbon-based solvent include dichloromethane, trichloromethane, dichloroethane, or trichloroethane.

In addition, it is advantageous in terms of efficiency of the loading process that the loading method is carried out at a temperature of -70 to 200°C, preferably -50 to 150°C, and more preferably 0 to 100°C.

The alpha-olefin monomer used to prepare the ethylene-alpha-olefin copolymer of the present invention may be (C ₃ -C ₁₀ )alpha-olefin monomer, for example, propylene, 1-butene, 3-methyl-1-butene. , 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, and 1-tetradecene.

Meanwhile, the polymerization reaction of ethylene and alpha-olefin of the present invention may be carried out in a slurry phase, a liquid phase, a gas phase, or a bulk phase.

When the polymerization reaction is carried out in a liquid or slurry phase, a solvent, ethylene, or the alpha-olefin monomer itself can be used as a medium.

The solvent that can be used during the polymerization reaction may be an aliphatic hydrocarbon-based solvent, an aromatic hydrocarbon-based solvent, a halogenated aliphatic hydrocarbon-based solvent, or a mixture thereof.

Non-limiting examples of the aliphatic hydrocarbon-based solvent include butane, isobutane, pentane, hexane, heptane, octane, nonane, and decane. ), Undecane, Dodecane, Cyclopentane, Methylcyclopentane, or Cyclohexane.

The aromatic hydrocarbon solvent includes, but is not limited to, benzene, monochlorobenzene, dichlorobenzene, trichlorobenzene, toluene, xylene, or chlorobenzene. (Chlorobenzene), etc. may be mentioned.

The halogenated aliphatic hydrocarbon solvent includes, but is not limited to, dichloromethane, trichloromethane, chloroethane, dichloroethane, trichloroethane, or 1,2-dichloroethane. (1,2-Dichloroethane) and the like.

Meanwhile, the amount of the catalyst added in the polymerization reaction of the present invention is not particularly limited because it can be determined within a range where the polymerization reaction of the monomer can sufficiently occur depending on the slurry phase, liquid phase, gas phase, or bulk process.

However, according to the present invention, the amount of the catalyst added is 10 ^-8 to 1 mol/L, preferably 10 ^-7 to 10 based on the concentration of the central metal (M) in the main catalyst compound per unit volume (L) of monomer. It may be ^-1 mol/L, more preferably 10 ^-7 to 10 ^-2 mol/L.

In addition, the polymerization reaction of the present invention may be a batch type, semi-continuous type, or continuous type reaction, and is preferably a continuous reaction.

The temperature and pressure conditions for the polymerization reaction of the present invention can be determined considering the efficiency of the polymerization reaction depending on the type of reaction to be applied and the type of reactor, but the polymerization temperature is 100 to 200°C, preferably 120 to 160°C. The pressure may be 1 to 3000 atmospheres, preferably 1 to 1000 atmospheres.

For the polymerization reaction of the present invention, catalysts and reactants may be continuously added, and the reactants may be solvent, ethylene, alpha-olefin monomer, or a mixture thereof.

The reactant may be introduced into the polymerization reactor after undergoing heat exchange to remove the heat of polymerization.

Through the heat exchange, the temperature of the reactant can be reduced from -60°C to 0°C.

The catalyst and reactants can produce an ethylene-alpha-olefin copolymer through a plurality of polymerization reaction steps. For example, the catalyst and reactants can produce an ethylene-alpha-olefin copolymer through a primary polymerization step and a secondary polymerization step by two polymerization reactors set at different temperatures, as shown in FIG. 1.

The primary polymerization step may be performed in a primary polymerization reactor, and a continuous polymerization reactor in the form of a CSTR (Continuously Stirred Tank Reactor) may be used as the primary polymerization reactor.

In the first polymerization step, the pressure within the first polymerization reactor may be 30 bar to 100 bar, and more specifically, 60 bar to 100 bar.

If the pressure in the first polymerization reactor exceeds 100 bar in the first polymerization step, there may be a problem in which it becomes difficult to input monomers and catalysts, and if it is less than 30 bar, liquefaction of monomers may not occur and uneven polymerization may occur. there is.

In the first polymerization step, the temperature in the first polymerization reactor may be 120°C to 180°C, and more specifically, 140°C to 160°C.

If the temperature in the primary polymerization reactor exceeds 180°C in the first polymerization step, there may be a problem in that catalyst activity decreases, and if it is below 120°C, there may be a problem in that polymerization activation does not occur easily.

The secondary polymerization step may be performed in a secondary polymerization reactor, and the secondary polymerization reactor may be a continuous polymerization reactor in the form of a CSTR, a loop, a tube, or a pipeline. A polymerization reactor may be used.

In the secondary polymerization step, the pressure within the secondary polymerization reactor may be 30 bar to 100 bar, and more specifically, 60 bar to 90 bar.

If the pressure in the secondary polymerization reactor exceeds 100 bar in the secondary polymerization step, there may be a problem in which the product is not smoothly transported within the secondary polymerization reactor, and if the pressure is less than 30 bar, the product in the secondary polymerization reactor There may be a problem where a rapid flow occurs.

In the secondary polymerization step, the temperature within the secondary polymerization reactor may be 140°C to 200°C, and more specifically, may be 140°C to 180°C.

If the temperature in the secondary polymerization reactor exceeds 200°C in the secondary polymerization step, there may be a problem of polymerization of products with extremely low molecular weight, and if the temperature is below 140°C, it is produced through primary and secondary polymerization reactions. There is little difference in physical properties compared to the polymer produced when the reaction proceeds only in the first polymerization reactor, and therefore, the crosslinking time reduction effect of the present invention may not be sufficiently exerted.

Depending on the temperature conditions of the first and second polymerization reactors described above, a temperature difference may occur between the first and second polymerization reactors.

When a temperature difference occurs between the primary polymerization reactor and the secondary polymerization reactor as described above, a polymer product having two or more different characteristics, for example, excellent adhesion performance and crosslinking characteristics, can be obtained.

More specifically, the temperature difference between the primary polymerization reactor and the secondary polymerization reactor may be 10°C to 50°C, and more specifically, may be 15°C to 30°C.

If the temperature difference between the primary polymerization reactor and the secondary polymerization reactor is less than 10℃, there may be a problem of generating a large amount of low molecular weight abnormal polymer, and if it exceeds 50℃, the temperature of the product is not uniform, resulting in lower production volume and product properties. can affect.

Meanwhile, in the polymerization reaction of the present invention, a scavenger may be additionally added to further increase the effect of forming catalytically active species in the polymerization reactor by removing moisture and impurities in the solution containing the catalyst.

The scavenger is not particularly limited, but may be one or more types selected from the group consisting of compounds represented by the following formula (8).

[Formula 8]

D(R ³¹ ) ₃

In Formula 8, D is aluminum or boron, and R ³¹ is each independently a halogen radical, a (C ₁ -C ₂₀ )hydrocarbyl radical, or a (C ₁ -C ₂₀ )hydrocarbyl radical substituted with halogen.

The compound represented by Formula 8 is not particularly limited, but non-limiting examples include trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, and trihexylaluminum. , trialkyl aluminum such as Trioctylaluminum and Tridecyl Aluminum; Dialkyl aluminum alkoxides such as dimethylaluminum methoxide, diethylaluminum methoxide, and dibutylaluminum methoxide; Dialkyl aluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, and dibutylaluminum chloride; Alkyl aluminum dialkoxides such as Methylaluminum dimethoxide, Ethylaluminum dimethoxide, and Butylaluminum dimethoxide; Alkyl aluminum dihalides such as methylaluminum dichloride, ethyl aluminum dichloride, and butylaluminum dichloride; Trialkylboron such as trimethylboron, triethylboron, triisobutylboron, tripropylboron, and tributylboron; Or, tris pentafluorophenyl boron, etc. may be mentioned.

The amount of the scavenger used may be determined by the amount and activity of the main catalyst compound represented by Formula 1.

In addition, when a compound in which D is boron is used in the compound represented by Formula 8, the molar ratio to the main catalyst compound is 1:1 to 1:100, preferably 1:1 to 1:10, more preferably Can be used at a molar ratio of 1:1 to 1:3.

When a compound in which D is aluminum is used in the compound represented by Formula 8, the ratio is 1:1 to 1:1,000, preferably 1:1 to 1:500, more preferably 1:1 to 1, relative to the main catalyst compound. It can be used at a molar ratio of :100.

Meanwhile, the position where the scavenger is introduced into the polymerization reactor is not particularly limited. For example, the scavenger may be introduced together with the catalyst and reactants, or may be introduced into the primary or secondary polymerization reactor in a line separate from the line through which the catalyst and reactants are introduced.

The ethylene-alpha-olefin copolymer provided by the production method of the present invention has a high molecular weight, has a branched chain distribution of two or more, and can produce a stretch film with high tensile elongation due to various branched chain distributions, and can also be used at low temperatures. Since the crosslinking reaction occurs within a short period of time, it is possible to prevent deformations such as yellowing or heat shrinkage from occurring, and thus has excellent properties in terms of processing solar products.

Specifically, the ethylene-alpha-olefin copolymer may have a weight average molecular weight (Mw) of 10,000 to 1,000,000, preferably 50,000 to 800,000, and more preferably 230,000 to 500,000.

Additionally, the ethylene-alpha-olefin copolymer may have a molecular weight distribution (Mw/Mn) of 1 to 10, preferably 1.5 to 8, and more preferably 1.5 to 6.

Additionally, the ethylene-alpha-olefin copolymer may have a density of 0.857 to 0.903 g/mL.

The ethylene-alpha-olefin copolymer of the present invention has two elution peaks in TGIC analysis. For example, during TGIC analysis, it may have a first peak appearing at a first elution temperature of 35 to 70°C and a second peak appearing at a second elution temperature of 70 to 110°C.

At this time, the component having the first peak is rich in copolymers and has excellent adhesive properties, and the component having the second peak has relatively few copolymers but may have the property of easily crosslinking. Therefore, the ethylene-alpha-olefin copolymer of the present invention having the first and second peaks may have excellent adhesive performance and crosslinking properties simultaneously.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited by the following examples.

Example

<Synthesis Example> Synthesis of main catalyst compound (2)

Transition metal compound (2) was synthesized according to Scheme 2 below. The specific synthesis process is as follows.

[Scheme 2]

First, methyl lithium (1.63 g, 3.55 mmol, 1.6 M diethyl ether solution) was added dropwise to a diethyl ether solution (10 mL) in which compound (1) (0.58 g, 1.79 mmol) was dissolved at -30°C (( Step i).

The solution obtained in step (i) was stirred at room temperature overnight, then the temperature was lowered to -30°C, and 0.37 g (1.79 mmol) of Ti(NMe ₂ ) ₂ Cl ₂ was added at once (step (ii)).

The solution obtained in step (ii) was stirred for 3 hours, and then all solvent was removed using a vacuum pump. As a result, a red solid compound (2) was obtained (0.59 g, yield 75%).

Through the ^1H NMR spectrum, it was confirmed that two stereocompounds exist in a ratio of 1:0.8.

^1H NMR (C ₆ D ₆ ): d 7.12 and 7.09 (d, J = 7.2 Hz, 1H), 6.96 and 6.94 (d, J = 7.2 Hz, 1H), 6.82 and 6.80 (t, J = 7.2Hz, 1H),6.47 and 6.46(d, J =7.2Hz,1H), 6.45 and 6.44(d, J = 7.2Hz, 1H), 5.44(m, 1H, NCH),2.76-2.60(m, 1H, CH ₂ ), 2.44-2.18 (m, 1H, CH ₂ ), 2.28 and 2.22 (s, 3H), 2.09 (s, 3H), 1.74 and 1.65 (s, 3H), 1.88-1.48 (m, 2H, CH2), 1.20 and 1.18 (d, J = 7.2 Hz, 3H), 0.77 and 0.71 (s, 3H, TiMe), 0.49 and 0.40 (s, 3H, TiMe) ppm.

¹³ C{1H} NMR (C ₆ D ₆ ): d 159.83, 159.52, 145.93, 144.90, 140.78, 139.93, 139.21, 138.86, 135.26, 131.56, 129.69, 129.57, 127.50 , 127.46, 127.38, 127.24, 121.29, 121.16, 120.05, 119.96, 118.90, 118.74, 117.99, 117.74, 113.87, 110.38, 57.91, 55.31, 54.87, 51.68, 50.27, 50.12, 34.77, 27.58, 27 .27, 23.10, 22.05, 20.31, 19.90, 16.66, 14.70, 13.11, 12.98, 12.68 ppm. Anal. Calc. (C ₂₂ H ₂₇ NSTi): C, 68.56; H, 7.06; N, 3.63. Found: C, 68.43; H, 7.24; N, 3.52%.

<Example 1> .

Ethylene/1-octene copolymer was prepared by performing the following continuous polymerization process using a 2.5L polymerization reactor equipped with a stirrer:

The solvents, normal hexane 8.5 kg/hr, ethylene 1.5 kg/hr, and 1-octene 0.9 kg/hr, are passed through the primary heat exchanger to reach -40°C. The temperature was reduced to prepare a reactant, and the reactant was introduced into the first polymerization reactor.

The transition metal compound obtained in Synthesis Example 1 was introduced into the primary polymerization reactor at a flow rate of 0.114 mmol/hr, and the cocatalyst compound N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate was added at a flow rate of 0.3 mmol/hr. . Additionally, triisobutylaluminum, a scavenger, was added to the primary polymerization reactor at a flow rate of 23 mmol/hr.

The polymerization reaction was performed by setting the temperature of the first polymerization reactor to 150°C and the pressure within the polymerization reactor to 90 bar.

The intermediate product that underwent the first polymerization reaction was passed through a second polymerization reactor in the form of a pipeline to proceed with the second polymerization reaction. During the secondary polymerization reaction, the temperature of the secondary polymerization reactor was set to 160°C and the pressure was set to 90 bar.

After passing through the polymerization reactor, the obtained product was passed through a first recovery device at 40°C and 5 bar to recover the solvent, and then passed through a second recovery section at 30°C and 1 bar to recover residual n-hexane and unreacted ethylene.

The remaining ethylene/1-octene copolymer was recovered using a separation tower, and the ethylene/1-octene copolymer was solidified using a pellet molding machine.

<Example 2>

The same procedure as Example 1 was performed except that the temperature of the pipeline, which was the secondary polymerization reactor, was set to 180°C.

<Example 3>

The same procedure as Example 1 was performed except that the temperature of the pipeline, which was the secondary polymerization reactor, was set to 200°C.

<Comparative Example 1>

The procedure was the same as in Example 1 except that the temperature of the pipeline, which was the secondary polymerization reactor, was set to 150°C, the same as that of the primary polymerization reactor.

<Comparative Example 2>

The same procedure as Example 1 was performed except that the temperature of the first polymerization reactor was set to 180°C and the temperature of the pipeline, which is the second polymerization reactor, was set to 180°C, the same as that of the first polymerization reactor.

As a result of the polymerization reaction, the time required for the polymerization reaction from the introduction of the catalyst until the polymerization reaction was completed and discharged was estimated to be about 10 minutes, and the measured temperature difference between the first and second polymerization reactors is shown in Table 1 below.

	Example 1	Example 2	Example 3	Comparative Example 1	Comparative example 2
First reaction temperature (℃)	150	150	150	150	180
Secondary reaction temperature (℃)	160	180	200	150	180
Temperature difference (℃)	10	30	50	0	0
Catalyst activity (Kg/g-cat)	243	263	260	239	275
Branched chain distribution (peak number in TGIC analysis)	2	2	2	One	One

<TGIC (Thermal Gradient Interaction Chromatography) analysis>

Polymer Char's CFC (Cross-Fractionation Chromatography) equipment was used, and the sample to be analyzed was stirred at 150°C for 60 minutes to dissolve 1,2,4-trichlorobenzene (2.5 mg/mL), and then the dissolved sample was It is introduced into a TGIC (Thermal Gradient Interaction Chromatography) column at 1ml/min and then stabilized at 150°C for 20 minutes. The TGIC column is then cooled to 35°C at a cooling rate of 20°C/min. The temperature is raised from 35℃ to 130℃ in 5℃ increments and eluted with a GPC column at a flow rate of 1ml/min. The elution time at this time is 5 minutes, and the analysis time for each fraction is 20 minutes. After passing through the GPC column, an infrared detector (IR5) is used to determine the elution amount for each temperature fraction, the molecular weight and branched chain distribution of the polymer corresponding to each fraction. The peak area of each fraction is checked using the analysis software 'CFC calc', and n-heptane is used as an internal standard.

TGIC analysis of the ethylene-alpha olefin copolymers of Example 1 and Comparative Example 1 was performed using the above method, and the results of the analysis are shown in Figures 2 and 3.

As can be seen from Figure 2, the ethylene-1-octene copolymer obtained in Example 1 had a first peak at 35°C to 70°C and a second peak at 70°C to 100°C.

Meanwhile, as can be seen from Figure 3, the ethylene-1-octene copolymer obtained in Comparative Example 1 was found to have only one peak at 50°C to 90°C.

<Measurement of cross-linking time>

Crosslinking was performed by adding TBEC (tert-butylperoxy 2-ethylhexyl carbonate) as a crosslinking agent and TAIC (Triallyl isocyanurate) as a crosslinking aid to each of the obtained ethylene/1-octene copolymers in the amounts shown in Table 2.

In order to determine the crosslinking behavior characteristics, a film containing the crosslinking aid composition was manufactured in the form of a disk weighing 5 g and having a diameter of 4 cm, and the minimum torque ML and maximum torque MH until scorched at 150°C for 20 minutes were obtained. The values, T10 and T90 (the time it takes for the torque value to reach 10% and 90% saturation) were checked. These cross-linking behavior characteristics were measured using RPA2000 (Rubber process analyzer) from Alpha Technologies.

The crosslinking rate is the percentage (%) of the weight of the specimen remaining without being extracted in the organic solvent xylene, and was calculated by (100 - weight change rate).

		Example 1	Example 2	Example 3	Comparative Example 1	Comparative Example 2
crosslinking agent	TBEC	One phr
Cross-linking aid	TAIC	0.5 phr
crosslinking time	t90 (min)	23.5	15.0	15.5	29.0	28.5

<Physical property analysis>

As can be seen from Table 2, when each of the ethylene-1-octene copolymers obtained in Examples 1 to 3 according to the present invention is used, the crosslinking time is 15 to 23.5 minutes, and in Comparative Examples 1 and 2, The crosslinking time of the obtained ethylene-1-octene copolymer can be significantly shortened compared to 28.5 to 29 minutes, and therefore, when manufacturing an encapsulant for solar cells using the ethylene-alpha-olefin copolymer of the present invention, productivity is significantly increased. You can see that it can be improved.

Claims (10)

1. A first polymerization step of supplying reactants including a solvent, ethylene, and olefin monomers, and a catalyst to a polymerization reactor for polymerization; and

   Producing an ethylene-alpha-olefin copolymer comprising a secondary polymerization step after the primary polymerization step, wherein the secondary polymerization step is performed at a temperature 10°C to 50°C higher than the polymerization temperature of the first polymerization step. method.
2. The method of claim 1, wherein the first polymerization step is performed in a CSTR continuous polymerization reactor.
3. The method of claim 1, wherein the secondary polymerization step is performed in a CSTR continuous polymerization reactor, a loop, or a tubular polymerization reactor.
4. The method of claim 1, wherein the first polymerization step is performed at 120°C to 180°C.
5. The method of claim 1, wherein the secondary polymerization step is performed at 140°C to 200°C.
6. The method of producing an ethylene-alpha-olefin copolymer according to claim 1, wherein the catalyst includes a transition metal compound represented by the following formula (1):

   [Formula 1]

   

   (In Formula 1 above,

   M is a group 4 transition metal;

   Q ¹ and Q ² are each independently halogen, (C ₁ -C ₂₀ )alkyl, (C ₂ -C ₂₀ )alkenyl, (C ₂ -C ₂₀ )alkynyl, (C ₆ -C ₂₀ )aryl, ( C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl, (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl, (C ₁ -C ₂₀ )alkylamido, (C ₆ -C ₂₀ )arylamido or (C ₁ -C ₂₀ )alkylidene;

   R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently hydrogen; (C ₁ -C ₂₀ )alkyl with or without acetal, ketal or ether groups; (C ₂ -C ₂₀ )alkenyl with or without acetal, ketal or ether groups; (C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl with or without an acetal, ketal or ether group; (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl with or without an acetal, ketal or ether group; or (C ₁ -C ₂₀ )alkylsilyl with or without an acetal, ketal or ether group; R ¹ and R ² may be connected to each other to form a ring, R ³ and R ⁴ may be connected to each other to form a ring, and two or more of R ⁵ to R ¹⁰ may be connected to each other to form a ring. You can;

   R ¹¹ , R ¹² and R ¹³ are each independently hydrogen; (C ₁ -C ₂₀ )alkyl with or without acetal, ketal or ether groups; (C ₂ -C ₂₀ )alkenyl with or without acetal, ketal or ether groups; (C ₁ -C ₂₀ )alkyl(C ₆ -C ₂₀ )aryl with or without an acetal, ketal or ether group; (C ₆ -C ₂₀ )aryl(C ₁ -C ₂₀ )alkyl with or without an acetal, ketal or ether group; (C ₁ -C ₂₀ )alkylsilyl with or without acetal, ketal or ether groups; (C ₁ -C ₂₀ )alkoxy; or (C ₆ -C ₂₀ )aryloxy; R ¹¹ and R ¹² or R ¹² and R ¹³ may be connected to each other to form a ring.)
7. The method of claim 1, wherein the catalyst further includes a carrier.
8. An ethylene-alpha-olefin copolymer prepared by the ethylene-alpha-olefin copolymer production method of any one of claims 1 to 7.
9. The method of claim 8, wherein the ethylene-alpha-olefin copolymer has two elution peaks in TGIC analysis, a first elution peak at 35°C to 70°C and a second elution peak at 70°C to 110°C. -Alpha-olefin copolymer.
10. A resin composition for solar cell encapsulation comprising the ethylene-alpha-olefin copolymer of claim 8 and a crosslinking agent.

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