KR20210154673A - Ehylene acrylic acid copolymer and water-dispersive composition including the same - Google Patents

Abstract

The purpose of the present invention is to provide an ethylene-(meth)acrylic acid copolymer having improved light transmittance and adhesion and an aqueous dispersion composition comprising the same. The ethylene-(meth)acrylic acid copolymer according to embodiments of the present invention can have a content of a part having a melting temperature of 94℃ or higher measured by a successive self-nucleation and annealing (SSA) measurement method of 1.5% or less. The aqueous dispersion composition having high adhesion and transmittance can be prepared by using the ethylene-(meth)acrylic acid copolymer.

Description

Ethylene (meth)acrylic acid copolymer and aqueous dispersion composition comprising the same

The present invention is an ethylene-relates to a dispersion composition comprising (meth) acrylic acid copolymer, and this.

Ethylene-carboxylic acid copolymers such as ethylene-(meth)acrylic acid copolymers are used in various applications such as sealing materials, adhesives, packing materials, and optical films. For example, it may be prepared as an aqueous dispersion and used for forming a coating film or an adhesive layer. The aqueous dispersion may be applied to the surface of a polymer film, paper, metal foil, fabric, etc. and then applied to heat to form an adhesive or fusion layer.

In addition, in order to seal a bag made of a material such as vinyl or metal foil, a dispersion containing the ethylene-acrylic acid copolymer may be used. In this case, after the dispersion is applied to a portion of the object, a compression process with heating may be performed together with the object.

When the adhesive layer is formed with an aqueous dispersion containing an ethylene-(meth)acrylic acid copolymer, the light transmittance of the adhesive layer is low due to an aqueous dispersion that is opaque like milk, so that the object in the portion where the adhesive layer is formed may be covered. In addition, when the viscosity of the dispersion is too high, wettability may be deteriorated and a uniform sealing layer may not be formed.

In consideration of the above aspects, it is necessary to design the physical properties of the ethylene-acrylic acid copolymer to form an aqueous dispersion having improved transmittance and adhesion.

For example, International Patent Publication Nos. WO2005/085331 and WO2017/050589 disclose the formation of heat-sealable coatings using aqueous polymer dispersions.

International Patent Publication No. WO2005/085331 International Patent Publication No. WO2017/050589

One object of the present invention is to provide an ethylene-(meth)acrylic acid copolymer having improved light transmittance and adhesion, and an aqueous dispersion composition comprising the same.

In the ethylene-(meth)acrylic acid copolymer according to exemplary embodiments of the present invention, the content of the portion having a melting temperature of 94° C. or higher measured by SSA (Successive Self-nucleation and Annealing) measurement technique may be 1.5% or less.

In some embodiments, the content of the portion having a melting temperature of 94° C. or higher measured by a SSA (Successive Self-nucleation and Annealing) measurement technique may be 1.5% or less.

In some embodiments, the melt flow index (MFI) measured at 190° C. and 2.16 kg may be 200 to 1500 g/10 min.

In some embodiments, the (meth)acrylic acid content may be 15 to 30% by weight, and the ethylene content may be 70 to 85% by weight.

In some embodiments, the crystallization temperature measured by differential scanning calorimetry (DSC) may be 50 to 60°C.

In some embodiments, the melting temperature measured by differential scanning calorimetry (DSC) may be between 60 and 90°C.

The aqueous dispersion composition according to the exemplary embodiments of the present invention is an ethylene-(meth)acrylic acid copolymer having a content of 1.5% or less of a portion having a melting temperature of 94°C or higher measured by SSA (Successive Self-nucleation and Annealing) measurement technique, a neutralizing agent and an aqueous dispersion medium.

In some embodiments, it may have a solids content of 20 to 50% by weight relative to the total weight.

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

In some embodiments, the viscosity at 25° C. may be between 100 and 10,000 cP.

In some embodiments, the ethylene-(meth)acrylic acid copolymer may have a melt flow index (MFI) of 200 to 1500 g/10min measured at 190° C. 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 25 to 50%.

In some embodiments, the neutralizing agent may include at least one of NHOH, organic amine, KOH, NaOH, CsOH, and LiOH.

In some embodiments, a polyolefin-based polymer may be further included.

According to exemplary embodiments of the present invention, the ethylene-(meth)acrylic acid copolymer is 1.5% when the peak area according to the melting temperature is measured using the SSA analysis method, and the relative content of the portion having a melting temperature of 94°C or higher is calculated. may be below. Accordingly, an adhesive layer or a sealing layer having high light transmittance may be formed.

In addition, increase in viscosity and generation of insoluble components in the thermal process can be suppressed, thereby improving adhesion reliability and uniformity.

1 is a graph showing a temperature profile of an SSA (Successive Self-nucleation and Annealing) analysis method according to exemplary embodiments.
2 is a graph showing the SSA analysis results of the ethylene-(meth)acrylic acid copolymer pellets of Examples 1 to 3 and Comparative Example 1 and an aqueous dispersion composition comprising the same.

<Ethylene-(meth)acrylic acid copolymer>

Ethylene-(meth)acrylic acid (EAA) copolymer according to embodiments of the present invention may be prepared through a copolymerization reaction using ethylene and (meth)acrylic acid as monomers. As used herein, the term "(meth)acrylic acid" is used to mean both acrylic acid and methacrylic acid, or a derivative thereof (eg, (meth)acrylate).

Since the present invention may have various changes and may have various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

According to exemplary embodiments of the present invention, in the ethylene-(meth)acrylic acid copolymer, the content of the portion having a melting temperature of 94° C. or higher measured by SSA (Successive Self-nucleation and Annealing) measurement technique may be 1.5% or less.

SSA (Successive Self-nucleation and Annealing) uses a Differential Scanning Calorimeter (DSC) to reduce the temperature step by step and quench at the end of each step to preserve the crystals crystallized at the temperature at each step. to be.

That is, when the ethylene-(meth)acrylic acid copolymer is completely melted by heating, cooled to a specific temperature (T) and annealed slowly, molecules that are not stable at the temperature (T) are still melted Only solid and stable molecules crystallize. At this time, the stability to the temperature (T) depends on the distribution of the polymer of the molecules included in the ethylene-(meth)acrylic acid copolymer.

Therefore, by performing this heat treatment step by step, the distribution according to the polymer chain structure can be quantitatively measured, and accordingly, the distribution of each melting peak area can be measured.

1 is a graph showing a temperature profile of an SSA (Successive Self-nucleation and Annealing) analysis method according to exemplary embodiments.

Referring to FIG. 1, using a differential scanning calorimeter (device name: DSC822e, manufacturer: Mettler Toredo), the ethylene-(meth)acrylic acid copolymer may be heated in the range of -50 to 200°C. At this time, nitrogen as a purge gas may be supplied at a flow rate of 50 mL/min, and the rate of temperature increase may be adjusted to 10° C./min. Accordingly, all of the thermal history of the sample before measurement may be removed.

Next, step cooling may be performed. For example, after cooling to a temperature lower than 85°C (115°C) than the initial heating temperature of 200°C, it is maintained for 7 minutes. After that, the temperature is lowered to 10°C and then the temperature is increased again. In this way, the n+1-th annealing temperature can be maintained for another 7 minutes at a temperature 5° C. lower than the n-th annealing temperature. The heating temperature can be gradually lowered by making the holding time and the cooling temperature the same. For example, by advancing 37 step-step cooling segments (Segment), step-wise cooling may be performed from 200°C to 40°C. In this case, the rate of rise and fall of the temperature may be controlled at 10° C./min, respectively.

Lastly, in order to quantitatively analyze the distribution of crystals formed by repeating heating-annealing-quick cooling, the temperature was increased from -50°C to 200°C at a temperature increase rate of 10°C/min and the change in calorific value was observed and a thermogram (thermogram). ) can be measured.

In this way, when heating-annealing-quenching is repeated in the SSA method for the ethylene-(meth)acrylic acid copolymer of the present invention, peaks for each temperature appear, and the relative content of the peaks according to the melting temperature section can be calculated from this. In this case, the relative content of the peak may be defined as a ratio of the peak area in the melting temperature section (94° C. or higher) to the area of the crystal melting peak in the entire temperature range.

_{According to exemplary embodiments, the content of the melting temperature (T m} ) 94° C. or higher portion measured by SSA (Successive Self-nucleation and Annealing) measurement technique may be 1.5% or less, preferably 1% or less, More preferably, it may be 0.5% or less. In addition, the content of the melting temperature (Tm) 94 ℃ or higher portion may be 0.02% or more.

The content of the melting temperature (T _m ) of 94° C. or higher may be calculated by Equation 1 below.

[Equation 1]

The ethylene-(meth)acrylic acid copolymer of the present invention has the peak area distribution according to the melting temperature as described above, so that a small amount of comonomer, that is, low density characteristics and high transparency can be maintained. Accordingly, an adhesive layer or a sealing layer having high light transmittance may be formed by the aqueous dispersion composition including the ethylene-(meth)acrylic acid copolymer.

According to exemplary embodiments, the melt flow index (MFI) of the ethylene-(meth)acrylic acid copolymer may be in the range of 200 to 1500 g/10min at ^{190°C and 2.16 kg.}

The melt flow index may indicate the high temperature flowability of the polymer. According to exemplary embodiments, by controlling the melt flow index of the ethylene-(meth)acrylic acid copolymer to 200 g/10min or more, fast application and fusion properties can be implemented even in a low-temperature sealing process. In addition, a uniform coating layer may be formed due to an increase in meltability or flowability, and stable thermal adhesion may be exhibited.

When 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 decrease. Therefore, according to exemplary embodiments, the melt flow index of the ethylene-(meth)acrylic acid copolymer may be adjusted to 1500 g/10min or less. If the melt flow index of the copolymer exceeds 1500 g/10min, it may be substantially difficult to commercialize the copolymer in the form of, for example, pellets because the flowability of the product is too high.

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

According to exemplary embodiments, the content of (meth)acrylic acid (eg, (meth)acrylic acid-derived units or (meth)acrylic acid-derived blocks) in the total weight of the ethylene-(meth)acrylic acid copolymer is 15 to 30 weights It can be %. In this case, the content of ethylene (eg, ethylene-derived units or ethylene-derived blocks) may be 70 to 85% by weight. In a preferred embodiment, the (meth)acrylic acid content may be 17 to 28% by weight and the ethylene content may be 72 to 83% by weight. More preferably, the (meth)acrylic acid content may be 19 to 26% by weight and the ethylene content may be 74 to 81% by weight.

When the content of (meth)acrylic acid is relatively small, the water dispersibility of the material may be low. When the content of (meth)acrylic acid is high, for example, process efficiency may be reduced by the production of polyacrylic acid, and excessive corrosion of manufacturing equipment may result. Therefore, by adjusting the content of (meth)acrylic acid to the above-mentioned range, it is possible to improve the adhesion of the coating layer or the sealing layer including the ethylene-(meth)acrylic acid copolymer.

_{According to exemplary embodiments, the crystallization temperature (T c} ) of the ethylene-(meth)acrylic acid copolymer measured by Differential Scanning Calorimeter (DSC) may be 50°C to 60°C.

Within the above range, the irregular ethylene-(meth)acrylic acid copolymer distribution changes regularly due to intermolecular attraction. have. Therefore, due to the transparent aqueous dispersion containing the ethylene-(meth)acrylic acid copolymer, the light transmittance of the adhesive layer is high, so that the target object in the portion where the adhesive layer is formed may not be covered.

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

The melting temperature (Tm) of the ethylene-(meth)acrylic acid copolymer measured by the Differential Scanning Calorimeter (DSC) is 94° C. or higher at the melting temperature measured by the SSA (Successive Self-nucleation and Annealing) measurement technique. It is a physical property that is not related to the content of the part, and it is only the temperature at which the ethylene-(meth)acrylic acid copolymer changes from a solid state to a fluid liquid state, and means the temperature at which crystallinity disappears in the partially crystalline polymer. Since the melting temperature of the ethylene-(meth)acrylic acid copolymer measured by differential scanning calorimetry satisfies the above range, thermal bonding or thermal bonding process can be easily performed even at low temperatures.

Embodiments of the present invention provide a method for preparing the above-described ethylene-(meth)acrylic acid copolymer. According to 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 an initiator. The initiator may include, for example, a free radical initiator such as an organic peroxide or azo compound.

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

The chain transfer agent is, for example, a hydrocarbon-based compound such as pentane, hexane, cyclohexane, isobutane; ketone compounds such as acetone, diethyl ketone, and methyl ethone ketone; Alcohols such as methanol and ethanol may be included.

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

According to exemplary embodiments, the pressure in the reactor may be maintained in the range of 20,000 to 30,000 psi. The temperature in the reactor can be maintained at 200 to 260 °C. In the above pressure and temperature range, the above-described broad molecular weight distribution and high melt flow index can be easily realized.

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

<Water Dispersion Composition>

According to exemplary embodiments, an aqueous dispersion composition including the above-described ethylene-(meth)acrylic acid copolymer is provided. The aqueous dispersion composition may include the ethylene-(meth)acrylic acid copolymer, a neutralizing agent, and an aqueous dispersion medium.

As described above, in the ethylene-(meth)acrylic acid copolymer, the content of the portion having a melting temperature of 94°C or higher measured by SSA (Successive Self-nucleation and Annealing) measurement technique may be 1.5% or less. In addition, while the melt flow index (MFI) measured at 190 ° C. and 2.16 kg conditions is 200 to 1500 g/10 min, the crystallization temperature measured by differential scanning calorimetry (DSC) may be 50 to 60 ° C. For example, the ethylene-(meth)acrylic acid copolymer may be included in an amount of 5 to 60% by weight based on the total weight of the aqueous dispersion composition.

2 is a graph showing the SSA analysis results of the ethylene-(meth)acrylic acid copolymer pellets of Examples 1 to 3 and Comparative Example 1 and an aqueous dispersion composition comprising the same.

Referring to FIG. 2 , it is possible to calculate the ratio of the peak area in a specific melting temperature section to the area of the crystal melting peak in the entire temperature region for a portion of 94° C. or higher indicated by hatching.

In order to quantitatively analyze the distribution of crystals formed by repeating heating-annealing-quenching as described above, a thermogram can be measured by observing the change in heat quantity, for example, the horizontal axis represents the temperature and the vertical axis By indicating the amount of exothermic heat flow, it is possible to measure the change in the amount of heat according to the temperature.

When heating-annealing-quenching is repeated in the SSA method for the ethylene-(meth)acrylic acid copolymer of the present invention and an aqueous dispersion composition containing the same, peaks for each temperature appear, and from this, the relative content of the peaks according to the melting temperature section can be calculated. In this case, the relative content of the peak may be defined as a ratio of the peak area in the melting temperature section (94° C. or higher) to the area of the crystal melting peak in the entire temperature range.

According to exemplary embodiments, the content of the portion having a melting temperature (Tm) of 94° C. or higher may be 1.5% or less. Therefore, the ethylene-(meth)acrylic acid copolymer of the present invention can be used to form an adhesive layer or a sealing layer having high light transmittance from the aqueous dispersion composition.

The neutralizing agent may be mixed with, for example, an ethylene-(meth)acrylic acid copolymer to provide a substantially aqueous dispersion composition as a stable viscous fluid.

As the neutralizing agent, a basic compound may be used without particular limitation. In preferred embodiments, the neutralizing agent may include an organic base such as ammonium hydroxide or an amine-based compound. The neutralizing agent may also include an inorganic base such as KOH, NaOH, CsOH, and the like. These may be used alone or in combination of two or more.

As the degree of neutralization of the ethylene-(meth)acrylic acid copolymer by the neutralizing agent increases, the dispersibility of the aqueous dispersion composition may increase, and the amount of insoluble components may decrease. However, as the degree of neutralization increases, the viscosity of the aqueous dispersion composition increases, which may be disadvantageous in terms of coating properties and adhesion.

However, according to exemplary embodiments, by using the ethylene-(meth)acrylic acid copolymer having a relatively high melt flowability as described above, it is possible to suppress an excessive increase in viscosity and ensure a sufficient degree of neutralization.

The term "neutralization degree" used in the present application may refer to a ratio reacted or neutralized by a neutralizing agent among acid groups (carboxylic acid groups) included in the ethylene-(meth)acrylic acid copolymer.

According to some embodiments, the neutralization degree in the aqueous dispersion composition may be 25% to 50%. When the degree of neutralization is less than 25%, sufficient dispersibility and coating uniformity may not be ensured. When the degree of neutralization exceeds 50%, the increase in viscosity may not be sufficiently suppressed.

Preferably, the neutralization degree of the aqueous dispersion composition may be 25 to 40%. Within the above range, it is possible to suppress the increase in the viscosity of the aqueous dispersion composition, and to more effectively secure the coating uniformity.

According to exemplary embodiments, the transmittance of the aqueous dispersion composition with respect to light having a wavelength of 600 nm may be 50 or more. The transmittance may be measured by a colorimeter, and the transmittance of the aqueous dispersion composition does not mean that it is 50 or more only for light having a wavelength of 600 nm, but may have high transmittance for light in the entire visible ray region.

Therefore, while the conventional aqueous dispersion composition containing the ethylene-(meth)acrylic acid copolymer having a high acid content is opaque like milk and has low light transmittance, using the aqueous dispersion composition of the present invention, the light transmittance is high and the object It is possible to form a transparent adhesive layer or a sealing layer that does not cover it.

According to exemplary embodiments, the viscosity measured at 25° C. of the aqueous dispersion composition may be in the range of 100 to 10,000 cP. Preferably, the viscosity measured at 25° C. of the aqueous dispersion composition may range from 100 to 2,500 cP.

By satisfying the above viscosity range, an aqueous dispersion composition capable of forming a uniform adhesive layer or sealing layer may be provided.

In some embodiments, the aqueous dispersion composition may further include an additional polymer or resin within a range that does not impair low-temperature adhesion, high dispersibility, and low viscosity characteristics through the ethylene-(meth)acrylic acid copolymer.

For example, a polyolefin-based resin such as polyethylene or polypropylene may be added together within a range that does not impair the acid value and viscosity characteristics of the ethylene-(meth)acrylic acid copolymer.

In one embodiment, the solids content of the total weight of the aqueous dispersion composition may be 20 to 50%, preferably 30 to 40%. Within the above range, the volatile components are easily removed at a low temperature to form an adhesive layer or a sealing layer having high light transmittance.

The aqueous dispersion composition may be used as a sealing material for a packaging film including polyethylene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, and the like. For example, after coating the aqueous dispersion composition on the surface of the sealing part of the packaging film, a sealing layer or an adhesive layer can be easily formed through thermal compression.

As described above, the ethylene-(meth)acrylic acid copolymer or the aqueous dispersion composition has a transmittance of 50 or more with respect to light having a wavelength of 600 nm, so that it is possible to form an adhesive layer having high transmittance in the visible light region.

In addition, the aqueous dispersion composition may be coated on various objects such as paper, resin film, and metal foil to form an insulating structure such as an adhesive layer, an antistatic layer, and an encapsulation layer.

The aqueous dispersion composition may further include other additives within a range that does not impair physical properties such as dispersibility and thermal properties through the ethylene-(meth)acrylic acid copolymer. For example, additives may include antistatic agents, surfactants, inorganic particles, anti-blocking agents, and the like.

Hereinafter, experimental examples including specific examples and comparative examples are presented to aid understanding of the present invention, but these are merely illustrative of the present invention and do not limit the appended claims, the scope and spirit of the present invention It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope, and it is natural that such variations and modifications fall within the scope of the appended claims.

Examples and Comparative Examples

Example 1

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

Ethylene and acrylic acid (AA) as monomers, t-butyl peroctoate as initiator and isobutane as chain transfer agent were continuously injected into a continuous flow reactor (CSTR) at a constant dosing ratio. An ethylene-acrylic acid copolymer was prepared. Specifically, the weight ratio of AA in the copolymer was adjusted to 19 to 21%, and the initiator efficiency, ie, the amount of the initiator for producing 1 kg of the copolymer, was adjusted to be 1 to 2 g. The chain transfer agent was added in an amount of 6 vol% based on the volume of all components.

The reactor pressure was maintained at 30,000 to 32,000 psi, and the internal temperature of the reactor was maintained at 240 to 260°C. The outlet gas temperature from the compressor was maintained at 70°C.

The resulting copolymer reactant was separated and passed through an extruder to form pellets.

(2) Measurement of physical properties of ethylene-(meth)acrylic acid copolymer

1) Acrylic acid content (AA%) measurement method

The acrylic acid (AA%) content in the ethylene-acrylic acid copolymer was measured using Fourier Transform Infrared Spectroscopy. Deuterated Triglycine Sulfate was used as a detector, and the values were calculated using ResolutionPro™ software (Agilent).

Specifically, a sheet of 50 μm was prepared by pressing 120 mg of an ethylene-acrylic acid copolymer sample in pellet form for 30 seconds in a hydraulic hot press (130° C.). After measuring the background spectrum, the sample made of a sheet was fixed in the center of a film holder through which the IR beam passed. Measurements were carried out in transmission mode with a resolution of 4 cm-1 and a number of repeated measurements of 32 scans.

Three standard samples with known acrylic acid content were pre-treated in the same way as the measurement sample to calculate a calibration equation for the linear equation of the integral value of the C-O peak with respect to the content of acrylic acid. Thereafter, the acrylic acid content (%) was calculated by substituting the C-O peak integral value of the measurement sample into the calibration curve.

2) Melt flow index (MFI) measurement method

Melt flow index (MFI) was measured according to ASTM D1238. The measurement temperature is 125℃ and the weight of the weight is 2.16kg. The melt flow index (MFI) at the measurement temperature of 190℃ and the weight of 2.16kg was presented using a 20-fold correlation of the measured value according to ASTM D1238 (125℃ / 2.16kg).

3) Melting temperature (Tm) measurement method

Melting temperature was measured using a differential scanning calorimeter (Differential Scanning Calorimeter, device name: DSC822e, manufacturer: Mettler Toledo).

Specifically, 6 mg of a sample of the ethylene-(meth)acrylic acid copolymer in the pellet state was taken and placed in an aluminum crucible, and a lid including a pinhole was covered.

While supplying nitrogen as a purge gas at a flow rate of 50 mL/min, the temperature was raised to 10° C./min in the range of -50 to 200° C. (the first temperature increase section) and then maintained isothermal at 200° C. for 1 minute. Thereafter, the sample was crystallized by cooling from 200°C to 50°C at a rate of 5°C/min. The temperature was changed at -50 to 200 °C, 10 °C/min in the second temperature increase section, and the highest point of the melting peak occurring in the second temperature increase section was measured as the melting temperature (Tm).

4) Crystallization temperature (Tc) measurement method

The crystallization temperature was measured using Differential Scanning Calorimeter (device name: DSC822e, manufacturer: Mettler Toledo).

Specifically, 6 mg of a sample of the ethylene-(meth)acrylic acid copolymer in the pellet state was taken and placed in an aluminum crucible, and a lid including a pinhole was covered.

While supplying nitrogen as a purge gas at a flow rate of 50 mL/min, the temperature was raised to 10° C./min in the range of -50 to 200° C. (the first temperature increase section) and then maintained isothermal at 200° C. for 1 minute. Thereafter, the sample was crystallized by cooling from 200°C to 50°C at a rate of 5°C/min. The highest point of the crystallization peak occurring in the first cooling section was determined as the crystallization temperature (Tc).

5) High-density part (part with a melting temperature of 94°C or higher) % measurement method

The high-density fraction % was measured using a differential scanning calorimeter (Differential Scanning Calorimeter, measuring device: Mettler Toledo's DSC822e), a peak fractionation method, and SSA (Successive Self-nucleation/Annealing).

Specifically, 10 mg of an ethylene-(meth)acrylic acid copolymer sample in a pellet state was placed in an aluminum crucible and a lid including a pinhole was covered.

The experiment was conducted with 39 segments while supplying nitrogen as a purge gas at a flow rate of 50 mL/min. In order to remove the thermal history of the sample, the temperature was raised at 10 °C/min in the range of -50 to 200 °C (first temperature increase section), and stepwise cooling was performed using 37 segments (2nd to 38th). In order to increase the separation of the peaks, an isothermal process of 7 minutes was maintained during the cooling process, and a quenching step was inserted between stepwise cooling.

The temperature profile of the SSA (Successive Self-nucleation and Annealing) analysis is as shown in FIG. 1 .

(3) Preparation of aqueous dispersion composition

251 g of water was filled in a 1000 mL glass double jacket (Autoclave) container, and 75 g of the EAA copolymer prepared as described above was added thereto, and while stirring, 10.1 g of a 29 wt% aqueous ammonia solution was added as a neutralizer. Thereafter, the vessel was closed and heated to 110° C. while stirring was continued.

After 1 hour, the vessel was cooled to 60° C., and the undispersed components were removed by filtration.

Example 2

An ethylene-(meth)acrylic acid copolymer and an aqueous dispersion composition were prepared in the same manner as in Example 1, except that the reactor internal temperature was maintained at 243 to 260°C.

Example 3

In the same manner as in Example 1, except that the outlet gas temperature of the gas discharged from the compressor was maintained at 65 ° C. and the reactor internal temperature was maintained at 240 to 256 ° C., the ethylene-(meth)acrylic acid copolymer and water A dispersion composition was prepared.

Comparative Example 1

An ethylene-(meth)acrylic acid copolymer and an aqueous dispersion composition were prepared in the same manner as in Example 1, except that the outlet gas temperature from the compressor was maintained at 30°C.

The physical properties of the copolymer included in the aqueous dispersion composition prepared according to Examples and Comparative Examples are shown in Table 1 below.

division Acid content (AA%) MFI (g/10min) Content (%) of Tm 94℃ or higher Tm (DSC method, °C) Tc (℃) Example 1 19.8 244 0.42 78.2 57.2 Example 2 19.9 243 0.13 78 56.1 Example 3 20 305 0.03 76.5 53.3 Comparative Example 1 19.9 229 2.04 77.5 60.9

Evaluation of the physical properties of the aqueous dispersion composition

1) Measurement of transmittance

The transmittance of the aqueous dispersion compositions of Examples and Comparative Examples is measured using a spectrophotometer. Add distilled water to the 10mm measuring cell and calibrate it so that the transmittance is 100%. After that, after drying the same cell, about 8 ml of the aqueous dispersion composition is irradiated with light to measure transmittance at a wavelength of 600 nm.

2) Viscosity measurement

After the addition of the neutralizing agent, the viscosity at 25° C. of the aqueous dispersion compositions of Examples and Comparative Examples was measured using a viscometer (Brookfield DV-II, Rotor No. 2).

The measurement results are shown in Table 2 below.

division permeability 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 aqueous dispersion compositions of Examples exhibited improved light transmittance than Comparative Examples.

Claims (13)

SSA (Successive Self-nucleation and Annealing) the content of the portion above 94 ℃ melting temperature measured by the measurement technique is 1.5% or less, ethylene-(meth)acrylic acid copolymer.
The ethylene-(meth)acrylic acid copolymer according to claim 1, wherein the melt flow index (MFI) measured at 190°C and 2.16 kg is 200 to 1500 g/10 min.
The ethylene-acrylic acid copolymer according to claim 1, wherein the (meth)acrylic acid content is 15 to 30% by weight, and the ethylene content is 70 to 85% by weight.
The ethylene-(meth)acrylic acid copolymer according to claim 1, wherein the crystallization temperature measured by differential scanning calorimetry (DSC) is 50 to 60°C.
The ethylene-(meth)acrylic acid copolymer according to claim 1, wherein the melting temperature measured by differential scanning calorimetry (DSC) is 60 to 90°C.
Ethylene-(meth)acrylic acid copolymer having a content of 1.5% or less of a portion having a melting temperature of 94°C or higher measured by SSA (Successive Self-nucleation and Annealing) measurement technique;
corrector; and
An aqueous dispersion composition comprising an aqueous dispersion medium.
The aqueous dispersion composition according to claim 6, having a solids content of 20 to 50% by weight relative to the total weight.
The method according to claim 6, The transmittance to light of a wavelength of 600nm is 50 or more, the aqueous dispersion composition.
The aqueous dispersion composition according to claim 6, wherein the viscosity at 25°C is 100 to 10,000 cP.
The method according to claim 6, The ethylene- (meth) acrylic acid copolymer has a melt flow index (MFI) measured at 190 ℃ and 2.16 kg conditions of 200 to 1500 g / 10 min, the aqueous dispersion composition.
The method according to claim 6, The ethylene- (meth) acrylic acid copolymer has a neutralization degree of 25 to 50% of the acid group, the aqueous dispersion composition.
The aqueous dispersion composition of claim 6 , wherein the neutralizing agent comprises _{at least one of NH 4} OH, organic amine, KOH, NaOH, CsOH, and LiOH.
The aqueous dispersion composition of claim 6, further comprising a polyolefin-based polymer.

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