CN112830988B - Ethylene vinyl acetate copolymer and preparation method thereof - Google Patents
Ethylene vinyl acetate copolymer and preparation method thereof Download PDFInfo
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- CN112830988B CN112830988B CN202011299771.7A CN202011299771A CN112830988B CN 112830988 B CN112830988 B CN 112830988B CN 202011299771 A CN202011299771 A CN 202011299771A CN 112830988 B CN112830988 B CN 112830988B
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- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 title claims abstract description 81
- 239000005038 ethylene vinyl acetate Substances 0.000 title claims abstract description 80
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 54
- 238000009826 distribution Methods 0.000 claims abstract description 31
- 230000008569 process Effects 0.000 claims abstract description 30
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical group CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 16
- 239000003607 modifier Substances 0.000 claims abstract description 13
- 239000000178 monomer Substances 0.000 claims abstract description 11
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000005977 Ethylene Substances 0.000 claims abstract description 10
- 239000003505 polymerization initiator Substances 0.000 claims abstract description 8
- 229920000642 polymer Polymers 0.000 claims abstract description 7
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 5
- 238000000576 coating method Methods 0.000 claims description 28
- 239000011248 coating agent Substances 0.000 claims description 27
- 238000012545 processing Methods 0.000 claims description 25
- 230000001070 adhesive effect Effects 0.000 claims description 18
- 239000000853 adhesive Substances 0.000 claims description 16
- 238000001125 extrusion Methods 0.000 claims description 14
- -1 polypropylene Polymers 0.000 claims description 12
- 239000004743 Polypropylene Substances 0.000 claims description 11
- 238000007765 extrusion coating Methods 0.000 claims description 11
- 239000000155 melt Substances 0.000 claims description 11
- 229920001155 polypropylene Polymers 0.000 claims description 11
- 229920005989 resin Polymers 0.000 claims description 8
- 239000011347 resin Substances 0.000 claims description 8
- 238000000691 measurement method Methods 0.000 claims description 7
- 239000000758 substrate Substances 0.000 claims description 7
- 238000000465 moulding Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 17
- 238000007665 sagging Methods 0.000 abstract description 14
- 239000000123 paper Substances 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 8
- 229920001577 copolymer Polymers 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 238000003475 lamination Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000003999 initiator Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 238000012805 post-processing Methods 0.000 description 3
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 2
- FZACIZFMQSYWOM-UHFFFAOYSA-N C(C)(C)(C)C(C(=O)OO)CCCCC(C)(C)C.C(CCCCCC(C)(C)C)(=O)OOC(C)(C)C Chemical compound C(C)(C)(C)C(C(=O)OO)CCCCC(C)(C)C.C(CCCCCC(C)(C)C)(=O)OOC(C)(C)C FZACIZFMQSYWOM-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000004512 die casting Methods 0.000 description 2
- 238000007607 die coating method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005227 gel permeation chromatography Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 229920001684 low density polyethylene Polymers 0.000 description 2
- 239000004702 low-density polyethylene Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 150000002978 peroxides Chemical class 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- OIQNWJHRBIPDFR-UHFFFAOYSA-N tert-butyl benzenecarboperoxoate 2-tert-butylbenzenecarboperoxoic acid Chemical compound C(C)(C)(C)C1=C(C(=O)OO)C=CC=C1.C(C1=CC=CC=C1)(=O)OOC(C)(C)C OIQNWJHRBIPDFR-UHFFFAOYSA-N 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- WKGDPWHNSZNERH-UHFFFAOYSA-N C(C)(C)(C)C(C(=O)OO)(C)C.C(C(C)C)(=O)OOC(C)(C)C Chemical compound C(C)(C)(C)C(C(=O)OO)(C)C.C(C(C)C)(=O)OOC(C)(C)C WKGDPWHNSZNERH-UHFFFAOYSA-N 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical group CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000011127 biaxially oriented polypropylene Substances 0.000 description 1
- YICCTZQUAAGDTO-UHFFFAOYSA-N but-1-ene Chemical compound CCC=C.CCC=C YICCTZQUAAGDTO-UHFFFAOYSA-N 0.000 description 1
- ZMFDXQTVCRGRNM-UHFFFAOYSA-N but-2-ene Chemical compound CC=CC.CC=CC ZMFDXQTVCRGRNM-UHFFFAOYSA-N 0.000 description 1
- DQXBYHZEEUGOBF-UHFFFAOYSA-N but-3-enoic acid;ethene Chemical compound C=C.OC(=O)CC=C DQXBYHZEEUGOBF-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- OQXKWNNTBOKHCC-UHFFFAOYSA-N tert-butyl 2,2-dimethylpropaneperoxoate 2,2,4,4-tetramethylpentaneperoxoic acid Chemical compound C(C)(C)(C)CC(C(=O)OO)(C)C.C(C(C)(C)C)(=O)OOC(C)(C)C OQXKWNNTBOKHCC-UHFFFAOYSA-N 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000000052 vinegar Substances 0.000 description 1
- 235000021419 vinegar Nutrition 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/02—Ethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/001—Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/01—Processes of polymerisation characterised by special features of the polymerisation apparatus used
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F218/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid or of a haloformic acid
- C08F218/02—Esters of monocarboxylic acids
- C08F218/04—Vinyl esters
- C08F218/08—Vinyl acetate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2500/00—Characteristics or properties of obtained polyolefins; Use thereof
- C08F2500/12—Melt flow index or melt flow ratio
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Polymerisation Methods In General (AREA)
- Paints Or Removers (AREA)
- Graft Or Block Polymers (AREA)
Abstract
The present application provides an ethylene-vinyl acetate copolymer and a process for producing the same, wherein specific reactor conditions for providing an ethylene-vinyl acetate copolymer excellent in processability, particularly necking and sagging properties as opposite properties, in the production of the ethylene-vinyl acetate copolymer are disclosed. The preparation method of the ethylene vinyl acetate copolymer comprises the following steps: step a, polymerizing ethylene monomer and vinyl acetate monomer in an autoclave reactor in the presence of a polymerization initiator and a modifier for adjusting molecular weight distribution; and a step b of continuously performing polymerization by adding the polymer polymerized in the step a and unreacted monomers to a tubular reactor.
Description
Technical Field
The present application relates to an ethylene-vinyl acetate copolymer and a preparation method thereof, and more particularly, to an ethylene-vinyl acetate copolymer for extrusion coating and a preparation method thereof.
Background
A general extrusion coating and low density polyethylene or ethylene vinyl acetate resin for lamination are used for paper coating, kraft coating, etc. in waterproof applications, and are widely used for plastic films, etc. in laminating and thermal bonding applications.
Basically, from the viewpoint of molecular weight distribution characteristics, the broader the Molecular Weight Distribution (MWD), the smaller the extrusion load due to low molecular weight, the more stable flow characteristics are exhibited In the extruder, and the necking (Neck-In) characteristics due to high Melt tension (Melt tension) tend to be excellent at the time of T-die casting due to the higher high molecular weight.
However, in recent years, as productivity becomes important, a sagging (Draw down) characteristic is regarded as a more important processing property. Therefore, it is important to ensure drawdown by having a higher ejection rate and having fewer high molecular weight regions while bearing a load in the extruder by a narrower molecular weight distribution characteristic. That is, since the conventional broad molecular weight distribution and high molecular weight inhibit the drawdown property, maintaining the high molecular weight in balance plays an important role in adjusting the resin properties. In addition, in the case of a low molecular weight having an excessively wide distribution, accumulation (Die build-up) occurs at the time of T-Die casting, and thus it may be difficult to perform coating film formation.
In addition, in the case of an ethylene vinyl acetate copolymer provided by the conventional autoclave process, although there is an advantage in that the molecular weight distribution is relatively wide and advantageous design can be made in terms of necking characteristics or extrusion processability due to melt tension, the drawdown characteristics are relatively low, and if a modifier is added to enhance the drawdown characteristics, although the characteristics of the corresponding portion can be adjusted, there is a problem in that it is difficult to maintain a high molecular weight balance. In contrast, in the case of the ethylene vinyl acetate copolymer provided by the tubular process, although the molecular weight distribution is relatively narrow and the drawdown property is excellent, the melt tension is inferior to that of the resin provided by the autoclave process in terms of the resin properties, and the properties disadvantageous to the coating processability such as the necking property are exhibited.
In addition, korean laid-open patent No. 2019-0022642 and us laid-open patent No. 2014-0303309 disclose a high pressure polymerization method for forming an ethylene-based polymer in which a reactor structure is a tube reactor, an autoclave reactor or two reactors including a tube reactor and an autoclave reactor, but specific reactor conditions for improving necking and drawdown in the preparation of an ethylene-vinyl acetate copolymer are not mentioned.
Korean patent No. 1975696 relates to a method for separating reactor off-gas components and a related reactor system, in which a reactor system that may include a high-pressure tube type reactor and/or an autoclave reactor and is available in the preparation of polyolefin polymers is disclosed, but only a low-density polyethylene polymerization reaction is described in detail, and specific reactor conditions for improving necking and drawdown in the preparation of ethylene-vinyl acetate copolymer are not mentioned.
Japanese laid-open patent publication No. 2002-080652 discloses an ethylene-vinyl acetate copolymer produced by using an autoclave type polymerizer or a tube type polymerizer, but does not mention the combined use of polymerizers and the improvement of processability caused thereby.
Disclosure of Invention
The present application proposes specific reactor conditions for providing an ethylene vinyl acetate copolymer excellent in processability, particularly in necking and sagging properties, which are opposite properties, when preparing an ethylene vinyl acetate copolymer.
In order to solve the above problems, the present application provides a method for preparing an ethylene vinyl acetate copolymer, comprising: step a, polymerizing ethylene monomer and vinyl acetate monomer in an autoclave reactor in the presence of a polymerization initiator and a modifier for adjusting molecular weight distribution; and a step b of continuously performing polymerization by adding the polymer polymerized in the step a and unreacted monomers to a tubular reactor.
Further, there is provided a process for producing an ethylene-vinyl acetate copolymer, characterized in that the autoclave reactor has a pressure of 1,700kgf/cm 2 To 2,200kgf/cm 2 The upper temperature is 140 ℃ to 170 ℃, the lower temperature is 185 ℃ to 225 ℃, and the pressure of the tubular reactor is 1,700kgf/cm 2 To 2,200kgf/cm 2 The temperature is 185 ℃ to 225 ℃.
Further, there is provided an ethylene vinyl acetate copolymer prepared by the above method, having a melt index of 10g/10 min to 25g/10 min, a vinyl acetate content of 10 wt% to 30 wt%, a molecular weight distribution MWD expressed by Mw/Mn of 4 to 6, and a z-average molecular weight of 130,000 to 200,000, measured at 125 ℃ and under a load of 2.16kg based on ASTM D1238.
Further, there is provided an ethylene vinyl acetate copolymer prepared by the above method, having a necking ratio of 25% or less, a maximum processing speed of 100m/min or more, and an adhesive strength of 40kgf/cm, measured according to the following method 2 The above.
[ necking ratio measuring method ]
The prepared ethylene vinyl acetate copolymer was coated on a biaxially stretched polypropylene film at a die temperature of 230℃using an extrusion coater having a discharge width of 450mm, the ratio of the coating width to the discharge width at the time of molding at an extrusion coating processing speed of 60m/min and a coating thickness of 20 μm was calculated, and the necking ratio was calculated using {1- (coating width/discharge width) ×100 }.
[ maximum processing speed measurement method ]
The ethylene vinyl acetate copolymer was coated on a biaxially stretched polypropylene film at a die temperature of 230℃using an extrusion coater having a discharge width of 450mm and a resin discharge amount of 700g/min, and the coating was confirmed by increasing the processing speed and confirming the processing speed at the time when the film was not coated due to the disruption of the resin flow.
[ adhesion Strength measurement method ]
After coating the ethylene vinyl acetate copolymer on a biaxially stretched polypropylene film at a thickness of 40 μm, it was laminated to a black paper substrate printed by ink printing at 100℃and a speed of 3m/min, and then the adhesive strength between the paper and the ethylene vinyl acetate copolymer was measured using a universal tensile tester under a Load Cell of 100N (Load Cell 100N) and a speed of 200 mm/min.
According to the present application, by applying a plurality of processes in which an autoclave process and a tubular process are sequentially performed, the polymerization degree and the reduction in the high molecular weight can be adjusted by adjusting the reactor pressure and the temperature in a state where the molecular weight distribution of the ethylene vinyl acetate copolymer is maximized, and as a result, the high molecular weight region is reduced while having a narrower molecular weight distribution, and it is possible to produce an ethylene vinyl acetate copolymer excellent in both necking and sagging properties.
Further, by controlling the fluidity and vinyl acetate content of the ethylene-vinyl acetate copolymer in the multi-polymerization process, it is possible to prepare an ethylene-vinyl acetate copolymer excellent in the post-processing properties, i.e., adhesive strength.
Detailed Description
The present application will be described in detail with reference to preferred examples. It should be noted that the terms or words used in the present specification and claims should not be construed as limited to general or dictionary meanings, but should be construed as meanings and concepts conforming to the technical ideas of the present application under the principle that the inventor can properly define the concepts of the terms in order to explain his own application in an optimal manner. Therefore, it should be understood that the configuration of the embodiment described in the present specification is merely a most preferable embodiment of the present application, and does not represent the whole technical idea of the present application, and that various equivalent embodiments and modifications can be made instead of the above embodiment in the present application stage.
In the conventional ethylene-vinyl acetate copolymer production, in the case of a single process using an autoclave reactor or a tubular reactor, it is difficult to satisfy both necking and sagging properties in the post-processing due to the opposite molecular weight characteristics, and it is difficult to solve the problem by process adjustment without proposing specific reactor conditions in the multi-process combining the autoclave reactor and the tubular reactor. The present inventors have focused on the above facts and circumstances, and as a result of repeated studies, have found that an ethylene-vinyl acetate copolymer excellent in both necking and sagging can be produced by adjusting the molecular weight characteristics of the ethylene-vinyl acetate copolymer by sequentially carrying out an autoclave process and a tubular process, and further by reducing the high molecular weight region while maximizing the molecular weight distribution of the ethylene-vinyl acetate copolymer by adjusting the pressure and temperature of each reactor.
Accordingly, the present application discloses a method for preparing an ethylene vinyl acetate copolymer, comprising: step a, polymerizing ethylene monomer and vinyl acetate monomer in an autoclave reactor in the presence of a polymerization initiator and a modifier for adjusting molecular weight distribution; and a step b of continuously performing polymerization by adding the polymer polymerized in the step a and unreacted monomers to a tubular reactor.
In the preparation of the ethylene-vinyl acetate copolymer in the present application, the molecular weight distribution (MWD, mw/Mn) is maximized by applying a multi-process in which an autoclave process and a tubular process are sequentially performed, thereby increasing the reduction range of the high molecular weight region regulated by the modifier, so that the molecular weight distribution can be relatively easily regulated. In addition, a narrower molecular weight distribution can be obtained by adjusting the reactor temperature and pressure to maximize the high molecular weight region reduction effect. Accordingly, it is possible to provide a copolymer having a relatively small high molecular weight region and a relatively narrow molecular weight distribution characteristic as compared with an ethylene vinyl acetate copolymer provided by an autoclave single process, thereby achieving excellent drawdown, and having excellent necking characteristics while having equivalent drawdown as compared with an ethylene vinyl acetate copolymer provided by a tubular single process. In addition, by controlling fluidity and vinyl acetate content while adjusting molecular weight characteristics, adhesive strength with paper printed with ink can be improved.
In the present application, the pressure of the autoclave sensor may be set at 1,700kgf/cm 2 To 2,200kgf/cm 2 The upper temperature may be set at 140 to 170 ℃, the lower temperature may be set at 185 to 225 ℃, and preferably the pressure may be set at 1,850kgf/cm 2 To 2,050kgf/cm 2 The upper temperature may be set at 145 to 165 ℃ and the lower temperature may be set at 195 to 215 ℃. Here, the upper temperature and the lower temperature of the autoclave reactor mean measured by temperature sensors (thermocouples) respectively provided at the highest position end of the reactor and the lowest position end of the reactorIs set in the temperature range of (a).
If the pressure of the autoclave reactor is less than 1,700kgf/cm 2 A large amount of long chain branches of the ethylene-vinyl acetate copolymer are formed and the Z-average molecular weight becomes large, and the drawdown property may be lowered in terms of processability, if the reactor pressure is more than 2,200kgf/cm 2 Problems may occur in terms of production stability by approaching the limit run value of the autoclave reactor, and long chain branches become too small and Z average molecular weight becomes small, and necking characteristics may be lowered in terms of processability.
Further, if the upper temperature of the autoclave reactor is lower than 140 ℃, the long chain branches of the ethylene-vinyl acetate copolymer decrease and the Z average molecular weight decreases, which may reduce the necking property in terms of processability, and if the upper temperature of the reactor is higher than 170 ℃, the long chain branches of the ethylene-vinyl acetate copolymer increase and the Z average molecular weight increases, which may reduce the sagging property in terms of processability.
Furthermore, if the lower temperature of the autoclave reactor is lower than 185 ℃, there may be caused a decrease in production load, if the lower temperature of the autoclave reactor exceeds 225 ℃, there may occur problems in stability of the reactor, and the drawdown may be reduced in processability due to an increase in the Z-average molecular weight of the ethylene vinyl acetate copolymer.
An initiator for initiating polymerization is used in the autoclave reactor. Although the kind of the polymerization initiator used is not limited, it is preferable to use two or more peroxides for the purpose of the present application, and from the viewpoint of meeting the above reaction temperature, for example, t-butyl peroxyneodecanoate (t-butyl peroxyneodecanoate) may be added to the upper portion of the reactor, and di-t-butyl peroxyisobutyrate (di-t-butyl peroxyisobutyrate) may be added to the lower portion.
Furthermore, a modifier for adjusting the molecular weight distribution is used in the autoclave reactor. The type of modifier used is not limited, but in view of the achievement of the object of the present application and the reactor conditions, C4-series olefinic hydrocarbon such as 1-butene (1-butene), 2-butene (2-butene), and isobutylene (iso-butyl) may be selected. In this case, the amount of the modifier to be added is preferably 120kg/hr to 200kg/hr, more preferably 140kg/hr to 180kg/hr. If the amount of the modifier added is less than 120kg/hr, it may be difficult to adjust the molecular weight distribution by the modifier, and if the amount of the modifier added exceeds 200kg/hr, the phenomenon of increase in melt index and density and decrease in Z-average molecular weight due to maximization of the production of low molecules may occur, whereby the necking characteristics may be lowered in terms of processability.
In polymerizing the ethylene vinyl acetate copolymer, vinyl acetate monomer is added to the autoclave reactor together with ethylene monomer, wherein the vinyl acetate monomer may be added in an amount of 10 to 30% by weight, preferably 15 to 23% by weight, of the final copolymer. If the vinyl acetate content is less than 10 wt%, the adhesive properties may be deteriorated, and if the vinyl acetate content exceeds 30 wt%, there is a high possibility that a crosslinked Gel (Gel) may be generated in the T-die extruder, and it may be difficult to apply to a coating process due to the excessively high adhesive properties.
For the ethylene vinyl acetate copolymer once polymerized in the autoclave reactor, as a continuous reaction process, a tube reactor disposed at the rear stage of the autoclave was charged with the once polymerized polymer and unreacted monomers, and an additional process was performed.
By the additional reaction carried out by the tubular reactor, about 1 to 10% by weight of an ethylene-vinyl acetate copolymer can be further produced, and about 10% by weight or more of an ethylene-vinyl acetate copolymer can be further produced depending on the process conditions, and by the secondary polymerization process by the tubular reactor, the molecular weight distribution of the ethylene-vinyl acetate copolymer becomes wider, and the productivity and production load can be increased.
In the present application, the pressure of the tubular reactor may be set at 1,700kgf/cm in consideration of necking and sagging properties due to the formation of moderately long chain branches of the ethylene-vinyl acetate copolymer 2 To 2,200kgf/cm 2 The reactor temperature may be set at 185℃to 225℃and preferably the pressure may be set at 1,850kgf/cm 2 To 2,050kgf/cm 2 The reactor temperature may be set at 195 ℃ to 215 ℃.
If the pressure of the tubular reactor is less than 1,700kgf/cm 2 The Z-average molecular weight becomes large due to the formation of a large amount of long chain branches of the ethylene-vinyl acetate copolymer, and the drawdown property may be lowered in terms of processability, and if the reactor pressure is more than 2,200kgf/cm 2 If the number of long chain branches is too small, the Z-average molecular weight may be reduced, and the necking property may be lowered in terms of processability.
Further, if the temperature of the tubular reactor is lower than 185 ℃, there is a possibility that the improvement of characteristics and the increase of production load due to additional reaction may be small due to the decrease of the reactivity, and if the temperature of the tubular reactor exceeds 225 ℃, the reactivity is unstable, and there may be a problem in stability due to the high-pressure, high-temperature reaction.
An initiator for initiating polymerization may be added to the tubular reactor. Although the kind of the polymerization initiator to be added is not limited, in order to achieve the object of the present application, it is preferable to use two or more peroxides, and from the viewpoint of the degree of activity in accordance with the reaction temperature, for example, an initiator such as t-butyl peroxybenzoate (t-butyl peroxybenzoate), t-butyl peroxy-3, 5-trimethylhexanoate (t-butyl peroxy-3, 5-trimethylhexanoate), t-butyl peroxyisobutyrate (t-butyl peroxyisobutyrate), t-butyl peroxypivalate (t-butyl peroxypivalate) or the like may be added in combination.
The ethylene vinyl acetate copolymer produced by the continuous polymerization process of the autoclave reactor and the tubular reactor may have a melt index (ASTM D1238, 125 ℃,2.16kg load) of 10g/10 min to 25g/10 min, a molecular weight distribution (MWD, mw/Mn) of 4 to 6, a z-average molecular weight of 130,000 to 200,000, and a vinyl acetate content of 10 wt% to 30 wt%, as previously described.
If the melt index of the ethylene-vinyl acetate copolymer is less than 10g/10 minutes, the necking property is excellent, but the sagging property is greatly reduced, and it is likely that high-speed processing is difficult due to a reduction in processing stability in the T-die coating, and if the melt index of the ethylene-vinyl acetate copolymer is more than 25g/10 minutes, the sagging property is relatively greatly improved, but the productivity may be reduced in the T-die coating process due to a deterioration in the necking property.
If the molecular weight distribution (MWD, mw/Mn) of the ethylene-vinyl acetate copolymer is less than 4, the extrusion load during extrusion processing becomes large, and if the molecular weight distribution is greater than 6, the neck-in property may be lowered in terms of processability, and if the molecular weight distribution is greater than 6, the drawdown property may be lowered in terms of processability. Likewise, if the Z-average molecular weight of the ethylene vinyl acetate copolymer is less than 130,000, necking characteristics may be degraded, and if the Z-average molecular weight of the ethylene vinyl acetate copolymer is greater than 200,000, sagging characteristics may be degraded.
In addition, for the ethylene vinyl acetate copolymer of the present application, a copolymer having an appropriate melt index and vinyl acetate content may be applied according to coating and lamination process speed conditions.
The coating and lamination process may be performed using conventional extrusion coating techniques by feeding ethylene vinyl acetate copolymer into an extrusion apparatus and causing it to be ejected as a melt toward a T-die for coating onto a substrate traveling through an underlying chill roll and nip roll. At this time, the melting temperature of the extruder may be set to 130 to 240 ℃, and the temperature of the T-die may be set to 210 to 240 ℃. The substrate travelling by the cooling roll and the nip roll may be a film of various materials, for example, a polyethylene terephthalate (PET) film, a biaxially oriented polypropylene (BOPP) film, or the like.
Here, the walking speed may be set to various speeds of 80 m/min to 300 m/min, and may be provided by differentiating the characteristics of the ethylene vinyl acetate copolymer according to the walking speed. That is, as for the medium-low speed ethylene vinyl acetate copolymer capable of being provided at a level of from 80 m/min to 150 m/min, a copolymer having a melt index of from 13g/10 min to 17g/10 min and a vinyl acetate content of from 16% by weight to 20% by weight is preferably applicable among the copolymers provided under the aforementioned polymerization conditions, and as for the high speed ethylene vinyl acetate copolymer capable of being provided at a level of from 150 m/min to 300 m/min, a copolymer having a melt index of from 18 g/min to 20 g/min and a vinyl acetate content of from 16% by weight to 22% by weight is preferably applicable.
According to the present application, an ethylene-vinyl acetate copolymer excellent in both necking and sagging properties can be produced.
Specifically, for the ethylene vinyl acetate copolymer prepared by the present application, the necking ratio measured according to the method described below may be 25% or less, and the maximum processing speed may be 100m/min or more.
[ necking ratio measuring method ]
The prepared ethylene vinyl acetate copolymer was coated on a biaxially stretched polypropylene film at a die temperature of 230℃using an extrusion coater having a discharge width of 450mm, the coating width at the time of molding at an extrusion coating processing speed of 60m/min and a coating thickness of 20 μm was measured, and the ratio of the coating width to the discharge width was measured to calculate the necking ratio.
[ maximum processing speed measurement method ]
When extrusion coating was performed using the ethylene vinyl acetate copolymer, the maximum processing speed of the extrusion coater at a screw speed of 35rpm was measured.
Further, according to the present application, an ethylene-vinyl acetate copolymer having excellent adhesive strength as a post-processing property can be produced.
The ethylene vinyl acetate copolymer is provided to the consumer as a final product after extrusion coating processing, e.g., the ethylene vinyl acetate copolymer applied to biaxially stretched polypropylene film and the ink printed paper are subjected to lamination processing. At this time, the substrate properties of the printed paper are important for physical adhesion due to the chemical adhesion of the ink used in printing and the relatively high roughness properties of the paper. Therefore, an appropriate melt index and vinyl acetate copolymer content are important in a range where extrusion processing operations can be performed. For the ethylene vinyl acetate copolymer prepared by the present application, the adhesive strength measured according to the above method may be 40kgf/cm 2 The above.
[ adhesion Strength measurement method ]
After coating the ethylene vinyl acetate copolymer (thickness 40 μm) on a biaxially stretched polypropylene film, it was laminated to a black paper substrate printed by ink printing at 100℃and a speed of 3m/min, and then the adhesive strength between the paper and the ethylene vinyl acetate copolymer was measured using a universal tensile tester under a load cell of 100N and a speed of 200 mm/min.
Further, according to the present application, since the process sensitivity is lowered due to the multiple processes including the autoclave process and the tube process being continuously performed, the manufacturability and productivity can be improved. That is, the production method of the present application can improve the productivity by 1% to 20%, preferably by 5% to 20%, more preferably by 10% to 20% as compared with a single process of polymerization using only an autoclave reactor or a single process of polymerization using only a tubular reactor.
The present application will be described in more detail with reference to specific examples and comparative examples.
Example 1
The recycle gas was introduced by a purge gas compressor (Purge gas compressor) and the pressure was compressed to 5.0kgf/cm 2 Ethylene gas and vinyl acetate monomer were added to a primary compressor (Primary Compressor) at the same time as 250kgf/cm 2 Is maintained at a pressure of 1,600kgf/cm in a secondary Compressor (Hyper Compressor) 2 Is a state of (2).
Ethylene gas and vinyl acetate monomer, which were compressed at high pressure in a secondary compressor, were fed into an autoclave reactor, and the reactor pressure was set to 1,900kgf/cm 2 The upper temperature of the reactor was set to 150 ℃, the lower temperature of the reactor was set to 200 ℃, and 160kg/hr of 1-butene was added as a modifier. The polymerization initiator was diluted with hydrocarbon, t-butyl peroxyneodecanoate (t-butyl peroxyneodecanoate) was added to the upper part of the reactor, and di-t-butyl peroxyisobutyrate (di-t-butyl peroxyisobutyrate) was added to the lower part of the reactor. Ethylene vinegar discharged from autoclave reactorThe vinyl acetate copolymer, unreacted ethylene gas and acetate monomer were directly fed into a tubular reactor at a reactor pressure of 1,900kgf/cm 2 And carrying out additional reaction at the temperature of 200 ℃. In a tubular reactor, tert-butyl peroxybenzoate (t-butyl peroxybenzoate) and tert-butyl peroxy-3, 5-trimethylhexanoate (t-butyl peroxy-3, 5-trimethylhexanoate) were added as polymerization initiators. Ethylene-vinyl acetate copolymers having the melt index, vinyl acetate content and molecular weight characteristics of the following table 1 were prepared by adjusting residence time and the like together with pressure and temperature conditions of the autoclave reactor and the tubular reactor.
Examples 2 to 8 and comparative examples 1 to 2
Ethylene vinyl acetate copolymer was produced in the same manner as in example 1, except that the polymerization conditions of example 1 were changed to those described in the following table 1.
Test examples
Physical properties, processability and adhesive strength were measured on the prepared ethylene vinyl acetate copolymer by the following methods, and the results thereof are shown in table 1 below.
[ measurement method ]
(1) Melt Index (MI, melt Index)
Based on ASTM D1238, measurements were made at 125℃and under a load of 2.16 kg.
(2) Vinyl acetate content
Measurement was performed by using FT-IR equipment from Nicolet corporation, and 1980-2090cm as a reference Peak value (Peak) was obtained -1 And 580-670cm as peak of vinyl acetate -1 From which the content is calculated.
(3) Molecular weight Properties (molecular weight distribution (MWD, mw/Mn), Z-average molecular weight)
Based on ASTM D3536, measurement was performed using GPC (gel permeation chromatography) analysis.
(4) Necking ratio
The prepared ethylene vinyl acetate copolymer was coated on a biaxially stretched polypropylene film at a die temperature of 230℃using an extrusion coater having a discharge width of 450mm, the coating width at the time of molding at an extrusion coating processing speed of 60m/min and a coating thickness of 20 μm was measured, and the ratio of the coating width to the discharge width was measured to calculate the necking ratio.
(5) Maximum processing speed
In order to understand the drawdown characteristics, the maximum processing speed of the extrusion coater at a screw speed of 35rpm was measured while the extrusion coating was performed.
(6) Adhesive strength
After coating the ethylene vinyl acetate copolymer (thickness 40 μm) on a biaxially stretched polypropylene film, it was laminated to a black paper substrate printed by ink printing at 100℃and a speed of 3m/min, and then the adhesive strength between the paper and the ethylene vinyl acetate copolymer was measured using a universal tensile tester under a load cell of 100N and a speed of 200 mm/min.
(7) Production load
The hourly production amounts in each of the examples and comparative examples were automatically measured by a Control panel (Control channel) of the production apparatus.
TABLE 1
Referring to table 1, it is apparent that, when the autoclave process and the tubular process were sequentially performed according to the present application, the reactor pressure and temperature, the melt index and the vinyl acetate content were adjusted to the preferred ranges (examples 1 and 2), the high molecular weight region was reduced while having a narrower molecular weight distribution, and thus the necking property and the sagging property were excellent, and further the excellent adhesive strength was exhibited.
In contrast, in the case of the single-process production without using the autoclave reactor and the tubular reactor, the drawdown property was insufficient due to the high Z-average molecular weight characteristic when the single-process production was performed by the autoclave reactor (comparative example 1), and the production load was reduced, and the drawdown property and drawdown property were the same as those of example 2 when the single-process production was performed by the tubular reactor (comparative example 2), but the adhesive strength was reduced, and the production load was reduced.
However, even though the multi-process of autoclave and tubular reactors was applied, it was confirmed that it was difficult to achieve satisfactory processing characteristics or adhesive strength characteristics when the pressure or temperature conditions of the reactors, or the Vinyl Acetate (VA) content slightly deviated from the preferred range.
That is, it was found that when the pressure in the autoclave reactor and the tubular reactor was slightly low (examples 3 and 4), the molecular weight distribution was broad, and the high molecular weight characteristics were exhibited, and as a result, the neck-in characteristics were excellent but the drawdown characteristics were reduced.
It was found that when the temperature of the autoclave reactor and the tubular reactor was slightly low or high (examples 5 and 6), the molecular weight distribution or the Z-average molecular weight did not satisfy the preferable physical properties, and as a result, the balance between the necking property and the sagging property was improved to a degree that the specific processing physical properties were exhibited, and when the temperature of the reactor was slightly low (example 5), the reaction temperature was lowered, and the production load was reduced.
Further, it was found that when the vinyl acetate content was slightly low (example 7), the adhesive strength characteristics were lowered, and when the vinyl acetate content was slightly high (example 8), the oxidation crosslinking occurred in the extruder due to the high vinyl acetate content, and the drawdown was significantly lowered.
The preferred embodiments of the present application have been described in detail above. The description of the present application is for illustration, and it should be understood by those skilled in the art that the present application may be easily modified into other specific forms without changing the technical idea or essential features of the present application.
The scope of the application should, therefore, be construed as limited by the appended claims rather than by the foregoing detailed description, and all changes or modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (2)
1. A method for preparing an ethylene vinyl acetate copolymer, which is characterized in that the method comprises the following steps:
step a, polymerizing ethylene monomer and vinyl acetate monomer in an autoclave reactor in the presence of a polymerization initiator and a modifier for adjusting molecular weight distribution; and
a step b of continuously carrying out polymerization by adding the polymer polymerized in the step a and unreacted monomers to a tubular reactor,
the autoclave reactor had a pressure of 1,850kgf/cm 2 To 2,050kgf/cm 2 The upper temperature is 145 ℃ to 165 ℃, the lower temperature is 195 ℃ to 215 ℃, and the pressure of the tubular reactor is 1,850kgf/cm 2 To 2,050kgf/cm 2 The temperature is 195 ℃ to 215 ℃,
the ethylene vinyl acetate copolymer has a melt index of 10g/10 min to 25g/10 min, a vinyl acetate content of 15 wt% to 23 wt%, a molecular weight distribution MWD expressed as Mw/Mn of 4 to 6, and a z average molecular weight of 130,000 to 200,000, measured based on ASTM D1238 at 125 ℃ and under a load of 2.16 kg.
2. An ethylene-vinyl acetate copolymer for extrusion coating, prepared by the method of claim 1, having a necking ratio of 25% or less, a maximum processing speed of 100m/min or more, and an adhesive strength of 40kgf/cm, measured according to the following method 2 The above-mentioned steps are carried out,
[ necking ratio measuring method ]
Coating the prepared ethylene vinyl acetate copolymer on a biaxially stretched polypropylene film at a die temperature of 230℃using an extrusion coater having a discharge width of 450mm, calculating a ratio of a coating width to a discharge width when molding at an extrusion coating process speed of 60m/min and a coating thickness of 20 μm, and calculating a necking ratio using {1- (coating width/discharge width) ×100},
[ maximum processing speed measurement method ]
Using an extrusion coater having a discharge width of 450mm and fixing the resin discharge amount to 700g/min, coating the biaxially stretched polypropylene film with the ethylene vinyl acetate copolymer at a die temperature of 230℃and increasing the processing speed to confirm the coating and confirm the processing speed at the time when the film was not coated due to the disruption of the resin flow,
[ adhesion Strength measurement method ]
After coating the ethylene vinyl acetate copolymer on a biaxially stretched polypropylene film at a thickness of 40 μm, it was laminated to a black paper substrate printed by ink printing at 100℃and a speed of 3m/min, and then the adhesive strength between the paper and the ethylene vinyl acetate copolymer was measured using a universal tensile tester at a load cell of 100N and a speed of 200 mm/min.
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| CN101072800A (en) * | 2004-11-02 | 2007-11-14 | 陶氏环球技术公司 | Process for producing low density polyethylene compositions and polymers produced therefrom |
| CN103237819A (en) * | 2010-09-30 | 2013-08-07 | 陶氏环球技术有限责任公司 | Polymerization process to make low density polyethylene |
| WO2019088664A2 (en) * | 2017-11-03 | 2019-05-09 | 주식회사 엘지화학 | Method for preparation of ethylene vinylacetate copolymer |
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| CN101072800A (en) * | 2004-11-02 | 2007-11-14 | 陶氏环球技术公司 | Process for producing low density polyethylene compositions and polymers produced therefrom |
| CN103237819A (en) * | 2010-09-30 | 2013-08-07 | 陶氏环球技术有限责任公司 | Polymerization process to make low density polyethylene |
| WO2019088664A2 (en) * | 2017-11-03 | 2019-05-09 | 주식회사 엘지화학 | Method for preparation of ethylene vinylacetate copolymer |
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