TW201725219A - Method of producing ethylene vinyl acetate copolymer resin and ethylene vinyl acetate copolymer resin produced by the same - Google Patents

Abstract

Provided are a method of producing an ethylene vinyl acetate copolymer (EVA) resin using a tubular reactor including at least two reactors, and an EVA resin produced by the method. The EVA resin producing method includes injecting an ethylene monomer and a vinyl acetate monomer into one reactor coupled to the monomer injection hole in a restrictive manner, adding a peroxide initiator, and performing polymerization at a temperature of 170 to 300 DEG C under the pressure of 2000 to 3000 kg/cm2for 2 to 20 minutes. Therefore, the EVA resin used as a foaming resin or an electric wire resin having a high crosslinking density and a high crosslinking speed can be easily provided.

Description

Method for producing ethylene/vinyl acetate copolymer resin and ethylene/vinyl acetate copolymer resin produced by the method

The present invention relates to a method for producing an ethylene/vinyl acetate copolymer (EVA) resin, which is a method for restricting the injection of a monomer into a tubular reactor, and an EVA resin produced by the method. The EVA resin has a high crosslinking density and a high crosslinking ratio.

Ethylene vinyl acetate copolymer (EVA) is a copolymer resin having a wide range of industrial applications. Compared to polyethylene (PE), EVA has several advantages, including: low crystallinity according to vinyl acetate content and a wide range of applications, from lightweight materials to soft materials, such as: hot melt adhesives, with low temperatures Performance and excellent impact resistance.

However, EVA also has several disadvantages, including: low chemical resistance, poor processability (due to increased adhesion with increasing vinyl acetate content), poor mechanical properties, and when combined with a foamed product. The strength of the pull that is reduced during use. In order to overcome these disadvantages, a process system for improving mechanical properties by partially cross-linking EVA is widely used. In the process of partially cross-linking EVA to improve processability and physical properties, the crosslink density and cross-linking speed of EVA resin significantly affect the processing and physical properties of the final product, which is a very important factor. .

Embodiments of the present invention provide a method for producing an ethylene/vinyl acetate copolymer (EVA) resin which has excellent crosslinking characteristics.

Embodiments of the present invention also provide an ethylene/vinyl acetate copolymer (EVA) resin having excellent crosslinking characteristics.

The above and other aspects of the invention are described or illustrated in the following description of exemplary embodiments.

According to one aspect of the present invention, there is provided a method for producing an ethylene/vinyl acetate copolymer (EVA) resin, which comprises: a tubular reactor comprising at least two reactors; An injection hole coupled to one end of the tubular reactor; and an EVA resin injector coupled to the other end of the tubular reactor, the method comprising: placing a vinyl sheet in a restrictive manner The body and monovinyl acetate monomer are only injected into the reactor coupled to the monomer injection port.

As described above, in the method according to an embodiment of the present invention, when it is applied to a crosslinking process by restrictively limiting a monomer injection method, it is possible to process an excellent crosslinking property. EVA resin.

Further, the EVA resin produced by the method according to an embodiment of the present invention can exhibit excellent characteristics including: high crosslinking density, excellent mechanical properties, and processability. Therefore, an EVA resin for use as a foamed resin or a wire resin can be easily provided.

The above information disclosed in this background section is only used to enhance the understanding of the background of the described technology, and thus it may contain information that is not known to those of ordinary skill in the art to which the present invention pertains. .

The embodiments of the present invention are described in detail below with reference to the accompanying drawings, which may be easily made and used by those of ordinary skill in the art.

The present invention provides a method for producing an ethylene/vinyl acetate copolymer (EVA) resin, which comprises: a tubular reactor comprising at least two reactors; a monomer injection hole coupled to One end of the tubular reactor; and an EVA resin injector coupled to the other end of the tubular reactor, the method comprising: treating a single ethylene monomer and a vinyl acetate in a limited manner The body is only injected into the reactor coupled to the monomer injection port.

In the production method of the EVA resin according to the present invention, when the ethylene monomer and the vinyl acetate single system injected into the reactor are additionally injected into a reactor or a system other than the reactor connected to the monomer injection hole When reacting in an autoclave reactor, it is difficult to improve the crosslinking speed and the crosslinking density due to the STI value of the product which increases with the same VA component and MI.

In a tubular reactor composed of two or more reactors, a reactor connected to the monomer injection port is referred to as a first-stage reactor, and a subsequent reactor system is referred to as a second stage. The reactor, the third stage reactor, depending on the number of reactors, and so on.

According to an embodiment of the present invention, the ethylene monomer and the vinyl acetate monomer are preferably injected at a ratio of 60 to 90: 10 to 40 by weight. If the content of the ethylene monomer in the EVA resin is more than 90% by weight or the content of the vinyl acetate monomer is less than 10% by weight, insufficient elasticity and flexibility are exhibited, making the EVA resin unsuitable for use as A foamed resin or a wire resin. Further, when the content of the ethylene monomer injected into the tubular reactor is less than 60% by weight or the content of the vinyl acetate monomer is more than 40% by weight, the polymerization reaction on the EVA resin will be difficult to proceed, which is not desirable. of.

According to an embodiment of the present invention, the method for producing the EVA resin further comprises: adding a polymerization initiator. The polymerization initiator may comprise: at least one selected from the group consisting of C4 to C40 dialkylperoxy dicarbonate-based compounds including di(2-ethylhexyl)peroxydicarbonate (di (2-ethylhexyl) peroxy-dicarbonate) and di-butyl peroxy-dicarbonate, C4~C20 alkylperoxy pivalate-based compounds including tert-amyl T-amyl peroxypivalate and t-butyl peroxypivalate, C4~C20 alkyl peroxyalkylhexanoate-based compounds (alkylperoxy alkylhexanoate-based) Compounds include t-amyl peroxy-2-ethyl hexanoate, t-butyl peroxy-2-ethylhexanoate (t-butyl peroxy-2-ethyl Hexanoate) and tert-butyl peroxy-3,5,5-trimethylhexanoate and C4~C20 dialkyl peroxide The -based compounds include a group consisting of di-t-butyl peroxide and di-t-amyl peroxide.

The peroxy polymerization initiator used in the present invention is preferably added at a concentration of 50 to 3,000 ppm, and the peroxy polymerization initiator contains at least one selected from the group consisting of (A) dialkylperoxy Dialkylperoxy dicarbonate-based compound, (B) alkylperoxy pivalate-based compound, (C) alkylperoxy ethyl hexanoate -based compound) and (D) a group consisting of dialkyl peroxide-based compounds. If the added concentration of the peroxygen initiator is less than 50 ppm, the reaction temperature during the polymerization is low, resulting in a low turnover rate of EVA, and it is not easy to control the molecular weight of the peroxy starter. This is not ideal. If the added concentration of the peroxygen initiator is more than 3,000 ppm, the reaction temperature during the polymerization is high, causing the EVA resin to be easily decomposed, and acetic acid is generated due to corrosion of the vinyl acetate in which the reactor is decomposed, This is not ideal.

According to an embodiment of the present invention, the polymerization temperature is preferably in the range of 170 to 300 °C. If the polymerization reaction temperature is lower than 170 ° C, the turnover rate of EVA becomes low, and it is difficult to achieve a desired molecular weight and a desired molecular weight distribution, which is not preferable. If the polymerization temperature is higher than 300 ° C, decomposition reaction will occur leading to corrosion of the reactor, thus undesirably reducing stability.

Further, the polymerization pressure is preferably in the range of from 2,000 to 3,000 kg/cm ² . If the polymerization pressure system is less than 2000 kg/cm ² , the reaction is insufficient to occur or the working stability is lowered, which is not desirable. If the polymerization pressure system is higher than 3000 kg/cm ² , a high pressure pump may limit performance and thus undesirably reduce stability.

Further, the polymerization reaction time is preferably in the range of 2 to 20 minutes. If the polymerization reaction time is shorter than 2 minutes, the turnover rate to EVA is low and the molecular weight is small, which is not preferable. If the polymerization time is longer than 20 minutes, it will not be easy to control the polymerization pressure, and gelation may occur, which is not desirable.

In order to attain the object of the present invention, the present invention provides an EVA resin produced by the production method of the EVA resin according to the present invention.

According to an embodiment of the present invention, the MI value of the EVA resin measured at 2.16 kg at 190 ° C is in the range of 0.5 to 30 g/10 min, and an advanced rheological expansion system (Advanced Rheometric Expansion System, ARES) Rheometer with a shear thinning index (STI) value greater than 13.987 for this MI under conditions of frequency sweep, 180 °C, and strain 10%. *MI ^-0.75 and less than 26.956*MI ^-0.687 ( ^13.987 *MI ^-0.75 < STI <26.956*MI ^-0.687 ).

If the MI system of the EVA resin is less than 0.5 g/10 min, the processability is poor and unsatisfactory. If the MI system of the EVA resin is more than 30 g/10 min, the melt tension is reduced and the crosslinking property is poorly exhibited, which is not preferable.

Using an ARES rheometer, the STI value measured for the MI is preferably greater than 13.987*MI ^-0.75 and less than 26.956*MI ^-0.687 (13.987*MI) under frequency sweep, 180 ° C and strain 10 %. ^-0.75 < STI <26.956*MI ^-0.687 ). If the STI value is less than 13.987*MI ^-0.75 , the crosslinking speed is too high, so premature curing or coking may occur, or an unpleasant appearance (eg, gel formation) may occur easily. If the STI value is greater than 26.956*MI ^-0.687 , it will be difficult to achieve the desired crosslink density and high crosslink speed.

In the present invention, additives may be added unless they would impair the nature or nature of the present invention. The additives may include: a hindered phenol-based antioxidant, a phosphite-based antioxidant, a lactone-based antioxidant, and a monoethanolamine group. An ethanol amine-based antioxidant, a hindered amine light stabilizer-based antioxidant, a UV stabilizer, a UV absorber, a neutralizer ), an anti-blocking agent, a slipping agent, a nucleating agent, a pigment, and the like.

The EVA resin according to the present invention is excellent in electrical insulation properties and withstand voltage characteristics, so that it can be desirably used for a tube, a wire coating, and the like. In addition, foamed products are manufactured using EVA's viscoelastic properties, which are used in insoles to absorb impact, electrically insulating products, tapes, sheets, and the like.

In the following, the invention will be further described in detail with reference to the accompanying drawings, which are not intended to limit the scope of the invention.

Example 1

A tubular reactor having two continuously connected reactors is used, and 82 wt% of ethylene monomer and 18 wt% of a vinyl acetate single system are produced by the production method of the EVA resin according to the present invention. A limited way is to inject only one of the monomer injection holes into one of the reactors. Subsequently, di(2-ethylhexyl) peroxy-dicarbonate, tert-butyl peroxy-pivalate, mixed in a ratio of (20/20/30/30) (t-butylperoxypivalate), t-butyl peroxy-2-ethyl hexanoate and tert-butylperoxy-3,5,5-trimethylhexanoate ( The mixture of tert-butyl peroxy-3,5,5-trimethylhexanoate was added as a radical generating catalyst at a concentration of 1200 ppm, and then polymerized at 2650 kg/cm ² using a high pressure pump for polymerization. The reaction pressure, the polymerization temperature of 235 ° C, and the polymerization reaction time of 3 minutes were carried out to the tubular reactor, whereby the EVA resin according to the present invention was produced.

Example 2

74 wt% of ethylene monomer and 26 wt% of vinyl acetate single system were injected into one monomer injection hole in one reactor in a limited manner, and propionaldehyde was concentrated at 70 ppm. As a one-chain transfer agent, which was a molecular weight modifier, an EVA resin was produced under the same polymerization conditions as in Example 1.

Example 3

72 wt% of ethylene monomer and 28 wt% of vinyl acetate single system were injected into one monomer injection hole of one reactor in a limited manner, except that the polymerization temperature was 190 ° C. This produced the EVA resin according to the present invention under the same polymerization conditions as in Example 1.

Example 4

67 wt% of ethylene monomer and 33 wt% of vinyl acetate single system were injected into one monomer injection hole of one reactor in a limited manner, and propionaldehyde was concentrated at 70 ppm. The EVA resin according to the present invention was produced as a one-chain transfer agent as a molecular weight modifier except that the polymerization temperature was 180 ° C, whereby the same polymerization conditions as in Example 1 were carried out.

Comparative example 1

82 wt% of ethylene monomer and 18 wt% of vinyl acetate single system are injected into the monomer injection hole of the first-stage reactor and the second-stage reactor in a ratio of 50 to 50 in one portion. The monomer was injected into the pores, whereby EVA resin was produced under the same polymerization conditions as in Example 1.

Comparative example 2

74 wt% of ethylene monomer and 26 wt% of vinyl acetate single system are injected into the monomer injection hole of the first stage reactor and the second stage reactor in a ratio of 50 to 50 in one portion. The monomer was injected into the pores, whereby EVA resin was produced under the same polymerization conditions as in Example 2.

Comparative example 3

A conventional EVA resin production process using a one-tube reactor is applied to 72 wt% of ethylene monomer and 26 wt% of vinyl acetate monomer, whereby the production can be commercially obtained from Arkema. EVA 28-03 product.

Comparative example 4

A conventional EVA resin production process using an autoclave reactor is applied to 67 wt% of ethylene monomer and 33 wt% of vinyl acetate monomer, whereby the production is commercially available from Lotte Chemical. EVA VC710 products.

The various physical properties of the EVA resin produced under the conditions of the examples and the comparative examples were measured by the following measurement methods, and the measurement results thereof are shown in Table 1.

Test case: measurement of physical properties

The various physical properties of the EVA resins produced in Examples 1-4 and Comparative Examples 1-4 were measured in the following manner and standards: 1) VA content: The VA content was measured by a differential scanning calorimeter (Differential Scanning Calorimeter). DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) measurements. 2) Melt Index (MI) : The MI value is filled at 2.16 kg at 190 ° C according to ASTM D1238. 3) shear thinning index (STI) : STI is measured using an ARES rheometer at a frequency sweep, 180 ° C and strain 10 %, and by a shear rate of 0.1 The value obtained by dividing the viscosity of the lower viscosity by the shear rate at 100 (w0.1/w100) is used. 4) Crosslinking density and crosslinking speed: 2 wt% of dicumyl peroxide (DCP) as a crosslinking agent was added to the EVA resin produced in the examples and the comparative examples, and obtained. The product was kneaded at 80 ° C for 5 minutes, followed by granulation at 90 ° C, and a curing curve of the compound was obtained using an Oscillating Disk Rheometer (ODR) at 180 ° C. In order to measure the cross-linking speed, the Δ-torque (MH - ML) value representing the difference between the minimum torque value (ML) and the maximum torque value (MH) is usually defined as the cross-linking density. And the time when the torque value corresponds to 10% of the value from the minimum torque value to the Δ torque (MH - ML) and the torque value corresponding to 90% of the value from the minimum torque value to the Δ torque (MH - ML) are respectively Defined as coking time (T10) and appropriate crosslinking time (T90). 5) Appearance: After cross-linking, the cross-linked product was identified by visual inspection, as well as surface roughness and gel formation. Table 1

As shown in Table 1 and Figure 1, the STI values of the EVA resins produced in Examples 1 to 4 were measured using an ARES rheometer with respect to the MI at a frequency sweep, 180 ° C, and strain of 10%. And the measured STI value is greater than 13.987*MI ^-0.75 and less than 26.956*MI ^-0.687 , ie ^13.987 *MI ^-0.75 < STI <26.956*MI ^-0.687 . The compounds prepared from the EVA resins produced in Examples 1 to 4 used the same amount of crosslinking agent, and the crosslinking characteristics thereof were evaluated. The evaluation results showed that the EVA resins were improved in crosslinking density and crosslinking speed compared to the comparative examples, and had good appearance characteristics.

Although the present invention has been particularly shown and described with respect to the exemplary embodiments thereof, it is to be understood that the present invention is in the technical field of the present invention without departing from the spirit and scope of the invention as defined in the following claims Often, knowledgers can make changes in many forms and details.

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The above and other features of the present invention will become more apparent from the detailed description of the exemplary embodiments and the accompanying drawings in which: FIG. The shear thinning index (STI) value measured by the EVA resin produced in Comparative Example 1-4 was compared with the MI (filled at 2.16 kg at 190 ° C). An Rheometric Expansion System (ARES) rheometer was measured at a frequency sweep of 180 ° C and a strain of 10%.

Claims (9)

A method for producing an ethylene vinyl acetate copolymer (EVA) resin, which comprises: a tubular reactor comprising at least two reactors; a monomer injection hole coupled To one end of the tubular reactor; and an EVA resin injector coupled to the other end of the tubular reactor, the method comprising: treating a vinyl monomer and a vinyl acetate in a restrictive manner The monomer is only injected into the reactor of the at least two reactors coupled to the monomer injection port. The method of claim 1, wherein the ethylene monomer and the vinyl acetate monolith are injected at a ratio of 60 to 90: 10 to 40 by weight. The method of claim 1, further comprising: adding at least one selected from the group consisting of (A) dialkylperoxy dicarbonate-based compounds, (B) alkane at a concentration of 50 to 3,000 ppm An alkylperoxy pivalate-based compound, (C) an alkylperoxy ethyl hexanoate-based compound, and (D) a dialkylperoxy compound ( A polymerization initiator of the group consisting of dialkyl peroxide-based compounds. The method of claim 3, wherein the polymerization initiator is at least one selected from the group consisting of di(2-ethylhexyl) peroxy-dicarbonate, dibutyl Di-butyl peroxy-dicarbonate, t-amyl peroxypivalate, t-butyl peroxypivalate, t-amyl peroxy -2-ethylhexanoate (t-amyl peroxy-2-ethyl hexanoate), t-butyl peroxy-2-ethyl hexanoate and t-butyl peroxyl -3,5,5-trimethylhexanoate, di-t-butyl peroxide, and di-tert-amyl peroxidation A group of di-t-amyl peroxide. The method of claim 1, wherein the tubular reactor is subjected to polymerization at a polymerization temperature of 170 to 300 ° C, a polymerization pressure of 2000 to 3000 kg/cm ^{2 ,} and a polymerization reaction time of 2 to 20 minutes. An ethylene vinyl acetate copolymer (EVA) resin produced by the method according to any one of claims 1 to 5. The EVA resin according to claim 6, wherein the EVA resin has a melt index (Melt Index, MI) of 0.5 to 30 g/10 min (190 ° C, 2.16 kg). The EVA resin according to claim 6, wherein an Advanced Rheometric Expansion System (ARES) rheometer is used, under conditions of frequency sweep, 180 ° C and strain of 10%. The shear thinning index (STI) value measured for the MI of the EVA resin is greater than 13.987*MI ^-0.75 and less than 26.956*MI ^-0.687 . The EVA resin according to claim 6, wherein the EVA resin is used as a foamed resin or a wire resin.