阅读说明：本技术 乙烯-(甲基)丙烯酸共聚物和包含其的水分散性组合物 (Ethylene- (meth) acrylic acid copolymer and water-dispersible composition comprising the same ) 是由 朴都演 郑周恩 黄秀英 孙相夏 郭炳圭 申海津 于 2021-06-10 设计创作，主要内容包括：一种乙烯-(甲基)丙烯酸共聚物具有熔融温度为94℃以上的部分。通过连续自成核与退火(SSA)分析测得的具有94℃以上的熔融温度的部分的含量为1.5％以下。一种水分散性组合物包含该乙烯-(甲基)丙烯酸共聚物、中和剂和水性分散介质。(An ethylene- (meth) acrylic acid copolymer has a portion having a melting temperature of 94 ℃ or higher. The content of a fraction having a melting temperature of 94 ℃ or higher, as measured by continuous self-nucleation and annealing (SSA) analysis, is 1.5% or less. A water-dispersible composition comprises the ethylene- (meth) acrylic acid copolymer, a neutralizing agent, and an aqueous dispersion medium.)

1. An ethylene- (meth) acrylic acid copolymer in which the content of a moiety having a melting temperature of 94 ℃ or higher, as measured by a continuous self-nucleation and annealing (SSA) analysis, is 1.5% or lower.

2. The ethylene- (meth) acrylic acid copolymer according to claim 1, wherein the Melt Flow Index (MFI) measured at 190 ℃ and 2.16kg is in the range of 200g/10 min to 1500g/10 min.

3. The ethylene- (meth) acrylic acid copolymer according to claim 1, wherein the content of (meth) acrylic acid is in the range of 15 to 30% by weight, and the content of ethylene is in the range of 70 to 85% by weight.

4. The ethylene- (meth) acrylic acid copolymer according to claim 1, wherein the crystallization temperature is 50 ℃ to 60 ℃ as measured by Differential Scanning Calorimetry (DSC) analysis.

5. The ethylene- (meth) acrylic acid copolymer according to claim 1, wherein the melting temperature is 60 ℃ to 90 ℃ as measured by Differential Scanning Calorimetry (DSC) analysis.

6. A water dispersible composition comprising:

an ethylene- (meth) acrylic acid copolymer in which the content of a moiety having a melting temperature of 94 ℃ or higher, as measured by a continuous self-nucleation and annealing (SSA) analysis, is 1.5% or lower;

a neutralizing agent; and

an aqueous dispersion medium.

7. The aqueous dispersible composition of claim 6, wherein the solid content of the composition is in the range of 20% to 50%.

8. The water-dispersible composition according to claim 6, wherein the transmittance for light having a wavelength of 600nm is 50% or more.

9. The aqueous dispersible composition of claim 6, wherein said composition has a viscosity of 100cP to 10000cP at 25 ℃.

10. The water dispersible composition of claim 6, wherein the ethylene- (meth) acrylic acid copolymer has a Melt Flow Index (MFI) in the range of 200g/10 minutes to 1500g/10 minutes measured at 190 ℃ and 2.16 kg.

11. The water dispersible composition of claim 6, wherein the degree of neutralization of acid groups contained in the ethylene- (meth) acrylic acid copolymer is 25-50%.

12. The aqueous dispersible composition of claim 6, wherein said neutralizing agent comprises a compound selected from NH₄At least one of OH, organic amine, KOH, NaOH, CsOH or LiOH.

13. The water dispersible composition of claim 6, further comprising a polyolefin-based polymer.

Technical Field

The present invention relates to an ethylene- (meth) acrylic acid copolymer and a water-dispersible composition comprising the same.

Background

For example, ethylene-carboxylic acid copolymers (e.g., ethylene-acrylic acid copolymers) are used in various products such as sealants, adhesives, packaging materials, and optical films. For example, the ethylene-carboxylic acid copolymer may be prepared as an aqueous dispersion (aqueous dispersion), and may be used to form a coating film or an adhesive layer. The aqueous dispersion may be applied to the surface of a polymer film, paper, metal foil, fabric, or the like, and then heated to form an adhesive or fused layer.

In addition, the dispersion containing the ethylene-acrylic acid copolymer may be used to seal a bag formed of a material such as a vinyl (vinyl) material or a metal foil. In this case, the dispersion may be applied to a portion of the object and then may be subjected to a pressing process including heating with the object.

When the adhesive layer is formed using an aqueous dispersion containing an ethylene- (meth) acrylic acid copolymer, the light transmittance of the adhesive layer may become low due to the opaque (e.g., milky) aqueous dispersion. Therefore, an object at a portion where the adhesive layer is formed may be optically shielded (shield). Further, when the viscosity of the dispersion becomes too high, wettability may decrease and a uniform sealing layer may not be formed.

In view of the above, the properties of the ethylene-acrylic acid copolymer used to form the aqueous dispersion may need to have improved transmittance and adhesion.

For example, international patent publications nos. WO2005/085331 and WO2017/050589 disclose the formation of heat-sealable coatings using aqueous polymer dispersions.

Disclosure of Invention

According to an aspect of the present invention, there is provided an ethylene- (meth) acrylic acid copolymer having improved light transmittance and adhesion.

According to one aspect of the present invention, there is provided a water-dispersible composition comprising an ethylene- (meth) acrylic acid copolymer having improved light transmittance and adhesion.

In the ethylene- (meth) acrylic acid copolymer according to the exemplary embodiment, the content of a moiety having a melting temperature of 94 ℃ or more, as measured by a continuous self-nucleation and annealing (SSA) analysis, is 1.5% or less.

In some embodiments, the Melt Flow Index (MFI) of the ethylene- (meth) acrylic acid copolymer, measured at 190 ℃ and 2.16kg, may be in the range of 200g/10 minutes to 1500g/10 minutes.

In some embodiments, the content of (meth) acrylic acid in the ethylene- (meth) acrylic acid copolymer is in the range of 15 to 30 wt% and the content of ethylene is in the range of 70 to 85 wt%.

In some embodiments, the ethylene- (meth) acrylic acid copolymer may have a crystallization temperature of 50 ℃ to 60 ℃ as measured by Differential Scanning Calorimetry (DSC) analysis.

In some embodiments, the ethylene- (meth) acrylic acid copolymer has a melting temperature of 60 ℃ to 90 ℃ as determined by Differential Scanning Calorimetry (DSC) analysis.

According to an exemplary embodiment, a water dispersible composition comprises an ethylene- (meth) acrylic acid copolymer, wherein the content of moieties having a melting temperature above 94 ℃ as measured by continuous self nucleation and annealing (SSA) analysis is 1.5% or less, a neutralizing agent, and an aqueous dispersing medium.

In some embodiments, the solids content of the composition may be in the range of 20% to 50%.

In some embodiments, the transmittance for light having a wavelength of 600nm may be 50% or more.

In some embodiments, the viscosity of the composition at 25 ℃ may be in the range of 100cP to 10000 cP.

In some embodiments, the ethylene- (meth) acrylic acid copolymer may have a Melt Flow Index (MFI) in a range from 200g/10 minutes to 1500g/10 minutes, measured at 190 ℃ and 2.16 kg.

In some embodiments, the degree of neutralization of the acid groups included in the ethylene- (meth) acrylic acid copolymer may be in the range of 25% to 50%.

In some embodiments, the neutralizing agent may include a compound selected from NH₄At least one of OH, organic amine, KOH, NaOH, CsOH or LiOH.

In some embodiments, the water dispersible composition may further comprise a polyolefin-based polymer.

In the ethylene- (meth) acrylic acid copolymer according to an embodiment of the present invention, the relative amount of the portion having a melting temperature of 94 ℃ or more, calculated from the peak area based on the melting temperature by SSA analysis, may be 1.5% or less. Accordingly, an adhesive layer or a sealing layer having high transmittance may be formed.

Further, an increase in viscosity and generation of insoluble components in heat treatment can be suppressed to improve adhesion reliability and uniformity.

Drawings

Fig. 1 is a graph illustrating a temperature profile in a continuous self nucleation and annealing (SSA) analysis according to an exemplary embodiment.

Fig. 2 is a graph showing the SSA analysis results of the ethylene- (meth) acrylic acid copolymer and the water dispersible composition according to examples 1 to 3 and comparative example 1.

Detailed Description

< ethylene- (meth) acrylic acid copolymer >

An ethylene- (meth) acrylic acid (EAA) copolymer according to an embodiment of the present invention may be prepared by a copolymerization reaction using ethylene and (meth) acrylic acid as monomers. The term "(meth) acrylic acid" as used in this application encompasses methacrylic acid and acrylic acid or derivatives thereof (e.g., (meth) acrylates).

Hereinafter, the present invention will be described in detail with reference to the attached experimental examples and drawings. However, those skilled in the art will understand that such embodiments, described with reference to the examples and drawings, are provided to further understand the spirit of the invention and are not limited to the claimed subject matter as disclosed in the detailed description and the appended claims.

According to an exemplary embodiment of the present invention, in the ethylene- (meth) acrylic acid copolymer, the content of the moiety having a melting temperature of 94 ℃ or more, as measured by an SSA (sequential self nucleation and annealing) measurement technique, may be 1.5% or less.

SSA (sequential self-nucleation and annealing) is a method of preserving crystals crystallized at respective temperatures by a method of rapidly cooling to gradually lower the temperature when each step is completed using a Differential Scanning Calorimeter (DSC).

For example, when an ethylene- (meth) acrylic acid copolymer is heated and completely melted, then cooled to a specific temperature (T) and gradually annealed, molecules that are unstable at the temperature (T) remain in a molten state, and only stable molecules can be crystallized. The stability to temperature (T) depends on the polymer distribution of the molecules comprised in the ethylene- (meth) acrylic acid copolymer.

Therefore, the above heat treatment can be performed in a stepwise manner, so that the degree of distribution according to the polymer chain structure can be quantitatively measured, and thus the distribution of each melting peak area can be measured.

Fig. 1 is a graph illustrating a temperature profile in a continuous self nucleation and annealing (SSA) analysis according to an exemplary embodiment.

Referring to FIG. 1, an ethylene- (meth) acrylic acid copolymer can be heated in the range of-50 ℃ to 200 ℃ using a differential scanning calorimeter (trade name: DSC822e, manufactured by Mettler Toedeo). In this step, nitrogen gas may be supplied as a purge gas at a flow rate of 50 mL/min, and the rate of increase in temperature may be adjusted to 10 ℃/min. Thus, the thermal history of the sample before measurement can be substantially removed.

Next, gradual cooling may be performed. For example, the sample is cooled to a temperature (115 ℃) 85 ℃ lower than the initial heating temperature 200 ℃ and held for 7 minutes. Thereafter, the temperature was lowered to 10 ℃, and then the temperature was raised again. In this way, the annealing temperature of the (n +1) th stage is 5 ℃ lower than that of the nth stage and is maintained for another 7 minutes.

The holding time (maintence time) and the cooling temperature may be constant, and the heating temperature may be gradually decreased. For example, the stepwise cooling may be performed from 200 ℃ to 40 ℃ by performing 37 stepwise cooling stages. The rate of increase in temperature and the rate of decrease in temperature may each be adjusted to 10 deg.c/minute.

Finally, the temperature was increased from-50 ℃ to 200 ℃ at a rate of 10 ℃/min, and the change in heat was observed to measure a thermogram (thermogram) to quantitatively analyze the distribution of crystals formed by repeating heating-annealing-rapid cooling.

As described above, the heating-annealing-rapid cooling using the SSA method may be repeated for the ethylene- (meth) acrylic acid copolymer to obtain a peak according to the temperature. From this, the relative content of the peak according to the melting temperature interval can be calculated. The relative content of peaks can be defined as the ratio of the area of the peak at the corresponding melting temperature interval (94 ℃ or higher) relative to the area of the crystal melting peak over the entire temperature range.

In exemplary embodiments, the content of the portion having a melting temperature (Tm) of 94 ℃ or more as measured by SSA (sequential self nucleation and annealing) measurement may be 1.5% or less, preferably 1% or less, and more preferably 0.5% or less. In one embodiment, the content of the portion having a melting temperature (Tm) of 94 ℃ or more may be 0.02% or more.

The content of the fraction having a melting temperature (Tm) of 94 ℃ or more can be calculated using the following equation 1.

[ equation 1]

A content of a melting temperature of 94 ℃ or higher (integrated value of peak area corresponding to a melting temperature of 94 ℃ or higher)/(integrated value of entire peak area)

The ethylene- (meth) acrylic acid copolymer according to an embodiment of the present invention may have a distribution of peak areas according to melting temperature as described above to maintain a small amount of comonomer, low density, and high transparency. Accordingly, a water-dispersible composition comprising an ethylene- (meth) acrylic acid copolymer can be used to form a bonding layer or a sealing layer having high light transmittance.

In an exemplary embodiment, the Melt Flow Index (MFI) of the ethylene- (meth) acrylic acid copolymer may be in a range of 200g/10 minutes to 1500g/10 minutes at 190 ℃ and 2.16 kg.

The melt flow index may be indicative of the flowability of the polymer at elevated temperatures. In exemplary embodiments, the melt flow index of the ethylene- (meth) acrylic acid copolymer may be adjusted to 200g/10 min or more, so that rapid application and adhesion may be achieved even during low-temperature sealing. In addition, a uniform coating layer can be formed due to the increase of meltability or fluidity, and stable thermal adhesiveness can be obtained.

If the melt flow index of the ethylene- (meth) acrylic acid copolymer is excessively increased, the heat resistance or mechanical strength of the sealing layer or the adhesive layer may be reduced. Thus, according to exemplary embodiments, the melt flow index of the ethylene- (meth) acrylic acid copolymer may be adjusted to 1500g/10 minutes or less.

If the melt flow index of the copolymer exceeds 1500g/10 minutes, the flowability of the product may become too high, and the actual manufacture of a product having, for example, a pellet shape (pellet shape) may become difficult.

In a preferred embodiment, the melt flow index of the ethylene- (meth) acrylic acid copolymer may be in the range of 500g/10 minutes to 1200g/10 minutes.

In exemplary embodiments, the content of (meth) acrylic acid (e.g., (meth) acrylic acid-derived units or (meth) acrylic acid-derived blocks) may be in the range of 15 wt% to 30 wt%, based on the total weight of the ethylene- (meth) acrylic acid copolymer. In this case, the content of ethylene (e.g., ethylene-derived units or ethylene-derived blocks) may be in the range of 70 wt% to 85 wt%.

In a preferred embodiment, the content of (meth) acrylic acid may be in the range of 17 to 28% by weight, and the content of ethylene may be in the range of 72 to 83% by weight. More preferably, the content of (meth) acrylic acid may be in the range of 19 to 26% by weight, and the content of ethylene may be in the range of 74 to 81% by weight.

If the content of (meth) acrylic acid is small, the water dispersibility of the copolymer may decrease. If the content of (meth) acrylic acid is high, the processing efficiency may be reduced due to the generation of polyacrylic acid, and excessive corrosion of manufacturing equipment may be caused. Accordingly, the content of (meth) acrylic acid may be adjusted within the above range, so that the adhesion of a coating layer or a sealing layer including the ethylene- (meth) acrylic acid copolymer may be improved.

In exemplary embodiments, the crystallization temperature (Tc) of the ethylene- (meth) acrylic acid copolymer, as measured by a Differential Scanning Calorimeter (DSC) method, may be in the range of 50 ℃ to 60 ℃.

Within the above range, the irregular distribution of the ethylene- (meth) acrylic acid copolymer may be changed to have a regular arrangement due to intermolecular attraction. Therefore, an ethylene- (meth) acrylic acid copolymer having high crystallinity and microstructure and having high transmittance can be easily prepared.

Accordingly, an adhesive layer (adhesive layer) or a bonding layer (bonding layer) having high light transmittance may be formed by using a transparent water-dispersible composition including an ethylene- (meth) acrylic acid copolymer. Therefore, the portion of the object on which the adhesive layer is formed may not be visually (vially) shielded.

In exemplary embodiments, the melting temperature (Tm) of the ethylene- (meth) acrylic acid copolymer measured by a Differential Scanning Calorimeter (DSC) method may be 60 ℃ to 90 ℃.

The melting temperature (Tm) of the ethylene- (meth) acrylic acid copolymer measured by a Differential Scanning Calorimetry (DSC) method may be a characteristic that is independent of the content of a portion having a melting temperature of 94 ℃ or more measured by an SSA (continuous self nucleation and annealing) method.

For example, the melting temperature (Tm) of the ethylene- (meth) acrylic acid copolymer measured by a Differential Scanning Calorimetry (DSC) method may be a temperature at which a solid state is converted into a liquid state, and may refer to a temperature at which crystallinity (crystallinity) in a partially crystalline polymer may be reduced or removed. Within the above range of the melting temperature of the ethylene- (meth) acrylic acid copolymer measured by the DSC method, a thermal bonding (thermal bonding) or thermal fusing (thermal fusing) process can be easily performed even at a low temperature.

According to an exemplary embodiment of the present invention, there is provided a method for preparing the above ethylene- (meth) acrylic acid copolymer. In exemplary embodiments, the ethylene- (meth) acrylic acid copolymer may be polymerized in a continuous process using a continuous flow reactor (CSTR).

For example, ethylene and (meth) acrylic acid as monomers may be introduced into the CSTR reactor together with the initiator. The initiator may comprise, for example, a free radical initiator, such as an organic peroxide or azo-based compound.

In some embodiments, a Chain Transfer Agent (CTA) may also be introduced into the reactor. Chain transfer agents may be included to terminate polymer chain growth to control the final molecular weight distribution. For example, the polymerization of the extended chain may be terminated by a chain transfer agent and may initiate the growth of a new polymer chain. The melt flow index of the ethylene- (meth) acrylic acid copolymer can be more easily controlled using a chain transfer agent.

The chain transfer agent may include, for example, hydrocarbon-based compounds such as pentane, hexane, cyclohexane and isobutane; ketone-based compounds such as acetone, diethyl ketone, and methyl ether ketone; alcohol-based compounds such as methanol and ethanol, and the like.

In some embodiments, a chain transfer agent may be used as a solvent to transfer ethylene or acrylic acid monomers. The content of the chain transfer agent may be adjusted within a range of 2 to 4 volume percent (vol%) based on the total volume of the components introduced into the reactor. Within this range, a sufficiently broad molecular weight distribution can be easily obtained while maintaining the above melt flow index range.

In exemplary embodiments, the pressure in the reactor may be maintained in the range of 20000psi to 30000 psi. The temperature in the reactor may be maintained at 200 ℃ to 260 ℃. Within the above pressure and temperature ranges, the above-mentioned broad molecular weight distribution and high melt flow index can be easily achieved.

The product obtained from the reactor may be processed, for example, into pellet (pellet) form.

< Water-dispersible composition >

According to an exemplary embodiment, there is provided a water-dispersible composition comprising the above ethylene- (meth) acrylic acid copolymer. The water dispersible composition may include an ethylene- (meth) acrylic acid copolymer, a neutralizing agent, and an aqueous dispersing medium.

As described above, in the ethylene- (meth) acrylic acid copolymer, the content of the portion having a melting temperature of 94 ℃ or more as measured by the SSA (continuous self nucleation and annealing) method may be 1.5% or less. The Melt Flow Index (MFI) measured under the conditions of 190 ℃ and 2.16kg may be 200g/10 min to 1500g/10 min, and the crystallization temperature measured by a Differential Scanning Calorimetry (DSC) method may be 50 ℃ to 60 ℃. For example, the ethylene- (meth) acrylic acid copolymer may be included in an amount of 5 wt% to 60 wt%, based on the total weight of the water dispersible composition.

Fig. 2 is a graph showing the SSA analysis results of the ethylene- (meth) acrylic acid copolymer and the water dispersible composition according to examples 1 to 3 and comparative example 1.

Referring to fig. 2, for the hatched portion above 94 ℃, the ratio of the peak area of a specific melting temperature interval to the area of the crystal melting peak in the entire temperature range was calculated.

As described above, the thermogram is measured by observing the change in heat quantity to quantitatively analyze the distribution of crystals formed by repeating heating-annealing-rapid cooling (quenching). For example, in fig. 2, the horizontal axis represents temperature and the vertical axis represents the value of the heat release flow, so that the change of heat quantity with temperature can be measured.

When the ethylene- (meth) acrylic acid copolymer and the water-dispersible composition according to the exemplary embodiment are repeatedly heated-annealed-rapidly cooled using the SSA method, a peak according to temperature is obtained, and thus the relative content of the peak according to the melting temperature interval can be calculated. In this case, the relative content of the peaks may be defined as the ratio of the area of the peak at the corresponding melting temperature interval (94 ℃ or higher) to the area of the crystal melting peak over the entire temperature range.

In an exemplary embodiment, the content of the portion having a melting temperature of 94 ℃ or more may be 1.5% or less. Accordingly, a tie layer or a sealing layer having high transmittance to light can be obtained from the water-dispersible composition including the ethylene- (meth) acrylic acid copolymer.

The neutralizing agent can be mixed with the ethylene- (meth) acrylic acid copolymer, and the water-dispersible composition can be prepared as a stable viscous fluid.

A basic compound may be used as the neutralizing agent. In a preferred embodiment, the neutralizing agent may comprise an organic based basic compound, such as ammonium hydroxide or an amine based compound. Alternatively, the neutralizing agent may include an inorganic basic compound, such as KOH, NaOH, CsOH, and the like. These compounds may be used alone or in combination thereof.

As the degree of neutralization of the ethylene- (meth) acrylic acid copolymer becomes greater, the dispersibility of the water-dispersible composition may increase and the amount of non-dispersible components may decrease. However, as the degree of neutralization of the ethylene- (meth) acrylic acid copolymer becomes larger, the viscosity of the water-dispersible composition may increase, thereby reducing coating and adhesive properties.

However, according to exemplary embodiments, an ethylene- (meth) acrylic acid copolymer having a relatively high melt flowability may be used. Therefore, a sufficient degree of neutralization can be achieved while preventing an excessive increase in viscosity.

The term "degree of neutralization" used herein may mean a ratio of acid groups (carboxyl groups) reacted or neutralized by a neutralizing agent among all acid groups contained in the ethylene- (meth) acrylic acid copolymer.

In some embodiments, the water-dispersible composition can have a degree of neutralization from 25% to 50%. If the neutralization degree is less than 25%, sufficient dispersibility and coating uniformity may not be obtained. If the degree of neutralization exceeds 50%, the viscosity of the composition may excessively increase.

Preferably, the water dispersible composition may have a degree of neutralization of 25% to 40%. Within this range, the viscosity increase can be suppressed, and the coating uniformity can be further improved.

In exemplary embodiments, the transmittance of the water-dispersible composition for light having a wavelength of 600nm may be 50% or more. The transmittance can be measured by a spectrophotometer. The water-dispersible composition can have high transmittance not only for light having a wavelength of 600nm but also for light of the entire visible light region.

For example, conventional water dispersible compositions comprising ethylene- (meth) acrylic acid copolymers with high acid content are opaque like milks (milk) and have low light transmittance. However, a transparent adhesive layer or a sealing layer having high transmittance so as not to shield an object may be formed using the water-dispersible composition according to an exemplary embodiment of the present invention.

In exemplary embodiments, the viscosity of the water-dispersible composition can range from 100cps to 10000cps as measured at 25 ℃. Preferably, the viscosity of the water-dispersible composition can range from 100cps to 2500cps measured at 25 ℃.

Within the above viscosity range, a water-dispersible composition from which a uniform adhesive layer or sealant layer can be formed can be provided.

In some embodiments, the water-dispersible composition may comprise other polymers or resins without degrading the characteristics of the ethylene- (meth) acrylic acid copolymer including low temperature bonding, high dispersion, and low viscosity properties.

For example, a polyolefin-based resin such as polyethylene, polypropylene, or the like may be added without lowering the acid value and viscosity of the ethylene- (meth) acrylic acid copolymer.

In one embodiment, the solids content based on the total weight of the water dispersible composition can range from 20% to 50%, preferably from 30% to 40%. Within this range, volatile components can be easily removed at low temperature to obtain a bonding layer or a sealing layer having high transmittance.

The water-dispersible composition can be used as a sealant for packaging films including, for example, polyethylene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, and the like. For example, the water-dispersible composition may be coated on the sealing surface of the packaging film, and then heat-pressed to easily form a sealing layer or a bonding layer.

As described above, the ethylene- (meth) acrylic acid copolymer or the water-dispersible composition may have a transmittance of 50% or more with respect to light corresponding to a wavelength of 600nm, so that a bonding layer having a high transmittance in a visible region may be formed.

The water-dispersible composition can be coated on various objects such as paper, resin films, metal foils, etc. to form an insulating structure such as an adhesive layer, an antistatic layer, an encapsulation layer, etc.

The water-dispersible composition may further comprise additives without reducing the dispersion or thermal properties of, for example, the ethylene- (meth) acrylic acid copolymer. For example, the additives may include antistatic agents, surfactants, inorganic particles, antiblocking agents, and the like, or combinations thereof.

Hereinafter, preferred embodiments are presented to more specifically describe the present invention. However, the following examples are given only for illustrating the present invention, and those skilled in the relevant art will clearly understand that various changes and modifications can be made within the scope and spirit of the present invention. Such changes and modifications are properly included in the appended claims.

Example 1

(1) Preparation of ethylene- (meth) acrylic acid copolymer

Ethylene and Acrylic Acid (AA) as monomers, t-butyl peroctoate as an initiator, and isobutane as a chain transfer agent were continuously injected into a Continuous Stirred Tank Reactor (CSTR) at a constant input ratio to prepare an ethylene-acrylic acid copolymer. Specifically, the weight ratio of AA in the copolymer was controlled to 19 to 20 wt%, and the initiator efficiency (i.e., the amount of initiator used to produce 1kg of copolymer) was adjusted to 1 to 2 g. The volume ratio of the chain transfer agent based on the total volume of the components was 6 vol%.

The pressure of the reactor is maintained within 30000psi to 32000psi and the temperature in the reactor is maintained within 240 ℃ to 260 ℃. The outlet gas temperature of the compressor was 70 ℃.

The copolymer product was isolated and formed into pellets (pellet) by an extruder.

(2) Measurement of ethylene- (meth) acrylic acid copolymer Properties

1) Measurement of acrylic acid content (AA%)

Acrylic acid content (AA%) in EAA copolymer was measured using fourier transform infrared spectroscopy. Deuterated triglycidyl sulfate was used as detector and specific values were obtained from resolutionpro (tm) Software (Agilent).

Specifically, 120mg samples of the EAA copolymer in particle form were pressed in a hydraulic hot press (130 ℃) for 30 seconds to make 50 μm sheets. The background spectrum was measured, and then the sheet was fixed in the middle of a film holder (film holder) through which an infrared beam (IR beam) passed. Measurements were made by transmission mode and 32 scans repeated.

The 3 standard samples whose acrylic acid content is known were also subjected to the pretreatment as described above, and a first-order calibration equation of the integrated value of the C-O peak with respect to the acrylic acid content was derived. The C — O peak integrated value of the sample was substituted into the calibration equation to obtain the acrylic acid content (%).

2) Measuring Melt Flow Index (MFI)

MFI was measured at 125 ℃ and under a load of 2.16kg based on ASTM D1238. MFI was calculated at 190 ℃ and 2.16kg using a 20-fold correlation with respect to the measurement based on ASTM D1238 (125 ℃ and 2.16 kg).

3) Measurement of melting temperature (Tm)

The melting temperature was measured using a differential scanning calorimeter (DSC 822e manufactured by Mettler Toledo).

Specifically, a 6mg sample of EAA copolymer in particle form was placed in an aluminum crucible covered by a lid including a pinhole.

Nitrogen was introduced as a purge gas at a flow rate of 50 mL/min. The temperature was increased at a rate of 10 c/min in the range of-50 c to 200 c (first warming period) and held at 200 c for 1 min. The sample was crystallized by cooling from 200 ℃ to 50 ℃ at a rate of 5 ℃/min. In the second temperature rise period, the temperature was changed from-50 ℃ to 200 ℃ at a rate of 10 ℃/min. The temperature of the melting peak in the second temperature-rise period was measured as the melting temperature (Tm).

4) Measurement of crystallization temperature (Tc)

The crystallization temperature was measured using a differential scanning calorimeter (DSC 822e manufactured by Mettler Toledo).

Specifically, a 6mg sample of EAA copolymer in particle form was placed in an aluminum crucible covered by a lid including a pinhole.

Nitrogen was introduced as a purge gas at a flow rate of 50 mL/min. The temperature was increased at a rate of 10 c/min in the range of-50 c to 200 c (first warming period) and held at 200 c for 1 min. The sample was crystallized by cooling from 200 ℃ to 50 ℃ at a rate of 5 ℃/min. The temperature of the crystallization peak in the first cooling period was measured as the crystallization temperature (Tc).

5) Measurement of the content (%) -of the high-density portion (portion having a melting temperature of 94 ℃ or higher)

The content of the high-density fraction was measured by peak band and SSA (continuous self nucleation/annealing) using a differential scanning calorimeter (DSC 822e manufactured by Mettler Toledo).

Specifically, a 10mg sample of the EAA copolymer in particle form was placed in an aluminum crucible covered by a lid including a pinhole.

The measurement was performed using 39 stages while introducing nitrogen as a purge gas at a flow rate of 50 mL/min. The temperature was raised at a rate of 10 c/min in the range of-50 c to 200 c (first warming period) to eliminate the thermal history of the sample, and then stepwise cooled using 37 stages (2 nd to 38 th). A 7 minute constant temperature period and a quenching step were inserted in the cooling step to improve peak resolution.

As shown in fig. 1, a temperature profile was obtained from SSA analysis.

(3) Preparation of Water-dispersible compositions

251g of water was charged to a 1,000mL glass double jacketed (autoclave) vessel. 75g of EAA copolymer were added and 10.1g of 29% by weight aqueous ammonia were introduced as neutralizing agent while stirring. The vessel was closed and heated to 110 ℃ while stirring was continued.

After 1 hour, the container was cooled to 60 ℃, filtered and the non-dispersible components were removed.

Example 2

An ethylene- (meth) acrylic acid copolymer and a water-dispersible composition were prepared by the same method as in example 1, except that the temperature in the reactor was maintained within 243 ℃ to 260 ℃.

Example 3

An ethylene- (meth) acrylic acid copolymer and a water-dispersible composition were produced by the same method as in example 1, except that the outlet gas temperature of the compressor was maintained at 65 ℃ and the temperature in the reactor was maintained within 240 ℃ to 256 ℃.

Comparative example 1

An ethylene- (meth) acrylic acid copolymer and a water-dispersible composition were produced by the same method as in example 1, except that the outlet gas temperature of the compressor was maintained at 30 ℃.

The properties of the copolymers included in the water dispersible compositions of the examples and comparative examples are shown in table 1 below.

[ Table 1]

Evaluation of Properties of Water-dispersible compositions

1) Measuring transmittance

The transmittance of the water-dispersible compositions of examples and comparative examples was measured using a spectrophotometer. Specifically, distilled water was added to a 10mm measuring cell (cell) and calibrated so that the transmittance was set to 100%. Thereafter, about 8ml of the water-dispersible composition was dried and placed in the same cell, and irradiated with light to measure transmittance at a wavelength of 600 nm.

2) Measurement of viscosity

The viscosities of the water-dispersible compositions of examples and comparative examples at 25 ℃ after addition of the neutralizing agent were measured using a viscometer (Brookfield DV-II, spindle number 52).

The results are shown in table 2 below.

[ Table 2]

	Transmittance of light	Viscosity (cP)
			Example 1	52.7％	273
Example 2	67.1％	304
			Example 3	68.3％	687
Comparative example 1	26.4％	627

Referring to table 2, the water dispersible compositions of the examples provided greater transmission than the transmission of the comparative examples.