KR101329729B1 - Porous coating membrane with shut-down characteristic and its manufacturing method - Google Patents

Abstract

The present invention relates to a porous coating film with an enhanced shut-down characteristic and a manufacturing method for the same. More specifically, by applying a shut-down coating layer including polymer resin with a shut-down characteristic on one side or both sides of a fine porous member which is used as a separation film for a secondary battery, the porous coating film has a relatively low shut-down temperature compared to other general porous materials and shows improved thermal stability overall.

Description

Porous coating membrane with shut-down characteristic and its manufacturing method

The present invention relates to a porous coating membrane with enhanced shutdown characteristics and a method for manufacturing the same, and more specifically, to a polymer resin having a shutdown characteristic on one or both surfaces of a microporous substrate used as a separator for secondary batteries. The present invention relates to a porous coating membrane having a relatively low shutdown temperature compared to a conventional porous substrate and having improved thermal stability as a whole by applying a shutdown coating layer including the same, and a method of manufacturing the same.

Recently, with the reduction in weight and miniaturization of various electronic products, lithium secondary batteries having a high energy density have been used in a wide range of fields such as mobile phones, laptops, and various power tools. In particular, as global warming accelerates, global attention is focused on electric vehicles (EVs) and hybrid vehicles (HEVs), which can significantly reduce carbon dioxide emissions. Development of secondary batteries is actively underway.

In general, a lithium secondary battery is composed of a positive electrode containing a positive electrode active material such as a lithium compound, a negative electrode containing a negative electrode active material such as a carbon material such as graphite, an electrolyte and a separator composed of a polymer porous membrane. Among these components, a separator that plays a most important role in the lifespan and stability of a secondary battery is a separator. Therefore, the development of a secondary battery depends in large part on the development of a suitable separator material.

Conventionally, a separator used for a lithium secondary battery is mainly a polyolefin-based film or a polyester nonwoven fabric, and the like, and the separator must electrically insulate the positive electrode and the negative electrode and must be permeable to the electrolyte. In addition, the thermal safety of the secondary battery depends on the shutdown temperature of the separator, the melt-down temperature, and the high-temperature heat-shrinkage ratio.

The shutdown temperature refers to a temperature at which the micropores inside the separator are closed and no more current flows when the temperature inside the battery is abnormally increased, and the melt breaking temperature is a separator when the temperature inside the battery continues to rise above the closing temperature. The melt shrinkage refers to the temperature at which electrical short occurs, and thermal shrinkage refers to the degree to which the dimension shrinks when the separator is exposed to a high temperature of 100 ° C. or higher. Therefore, in order to secure the stability of the secondary battery, it is necessary to develop a separator having a low shutdown temperature, a high melt fracture temperature, and a low thermal contraction rate.

In the past, efforts to improve the shutdown characteristics of the separator have been steadily progressed, for example, domestic patent registration No. 1011228 (2011.12.01. LG Chem), international patent application PCT / US2010 / 026425 (2010.03.05. Toray) Discloses a method for lowering the shutdown temperature of a porous substrate.

The LG Chem patent discloses a separator having a porous coating layer on at least one surface of a planar nonwoven substrate having a plurality of pores. The porous coating layer is formed of a mixture of a plurality of filler particles and a binder polymer, the filler particles are conductive PTC (Positive Temperature Coefficient) of a mixture of a low melting point resin and a plurality of conductive material particles having a melting point lower than the melting point of the nonwoven fabric substrate ) Particles.

The separator is provided with a function of closing pores during thermal runaway. However, in the LG Chem patent, the low melting point resin is limited only to the polyolefin resin, and thus the temperature at which the pores are closed is limited only to the melting point of the low melting point resin.

In addition, the Toray patent includes a first polyethylene having a molecular weight (Mw) of 1.010 ⁶ or more; Second polyethylene having a molecular weight (Mw) of 1.0 × 10 ⁵ to 0.95 × 10 ⁶ and a melting point (Tm) of greater than 127.0 ° C .; A separator showing a shutdown characteristic comprising a third polyethylene which is an ethylene-α-olefin copolymer having a molecular weight (Mw) of 1.0 × 10 ⁴ to 5.0 × 10 ⁶ and a melting point (Tm) of 115 to 127 ° C is introduced. However, in the case of the Toray patent, it is difficult to apply various polymers, and it leaves a considerable technical problem in terms of improving the impregnation of the electrolyte.

In addition, LG Chem's domestic patent registrations 739337 (2007.07.06.), 858214 (2008.09.04.), And 889207 (2009.03.06), etc., include inorganic particles and a binder polymer on the surface of a polyolefin-based porous substrate. By coating an active layer consisting of a technique for improving the thermal stability of the separator is introduced. However, these LG Chem patents only provide the effect of increasing the melt fracture temperature and lowering the heat shrinkage rate, and there is no report of a shutdown function that lowers the pore closing temperature.

1.Patent Registration No. 911228 (2011.12.01.LG Chem) 2. International patent application PCT / US2010 / 026425 (2010.03.05. Toray Tonen Kinoumaku Kodo Kaisha) 3. Patent registration No. 739337 (2007.07.06.LG Chem) 4. Patent registration No. 858214 (2008.09.04.LG Chem) 5. Patent registration No. 889207 (2009.03.06.LG Chem)

As described above, in order to secure the stability of the secondary battery, the thermal safety of the separator must be improved. In other words, membranes with low shutdown temperatures, high melt fracture temperatures and low thermal shrinkage should be developed. However, in general, when the shutdown temperature is lowered, the melt fracture temperature is lowered. When the melt fracture temperature is increased, the shutdown temperature is also increased.

The problem to be solved by the present invention is to provide a porous coating membrane and a method of manufacturing the same in the microporous coating membrane used as a secondary battery separator, in particular excellent in the shutdown characteristics and further improved thermal safety.

In the present invention, the shutdown characteristic refers to a function of preventing the current from flowing any more because the micropores inside the separator are closed when the temperature inside the battery increases abnormally.

The porous coating membrane according to the present invention is characterized in that a shutdown coating layer comprising a polymer resin having a shutdown characteristic is applied to one or both surfaces of the microporous substrate.

In this case, the shutdown coating layer is a coating slurry comprising 0.1 to 50 parts by weight of a polymer having a shutdown characteristic prepared by emulsion polymerization or suspension polymerization, 1 to 40 parts by weight of a binder resin, and 10 to 100 parts by weight of a dispersion solvent. It is characterized by being formed by coating.

Polymers having the above shutdown characteristics include (meth) acrylic copolymers, (meth) acryl-styrene copolymers, (meth) acryl-acrylonitrile copolymers, silicone- (meth) acrylic copolymers, epoxy- (meth) At least one selected from an acrylic copolymer, an ethylene copolymer, and a propylene copolymer.

Method for producing a porous coating membrane according to the present invention, A) 0.1 to 50 parts by weight of a polymer having a shutdown characteristic prepared by emulsion polymerization or suspension polymerization method, 1 to 40 parts by weight of binder resin, 10 to 100 weight of dispersion solvent Mixing the parts to prepare a coating slurry; B) applying the coating slurry on one or both sides of the porous substrate to a thickness of 0.5 ~ 10㎛ and dried to form a shutdown coating layer; characterized in that it comprises a.

In the porous coating membrane according to the present invention, the shutdown coating layer applied to the porous substrate may obtain a shutdown temperature of 130 ° C. or less regardless of the shutdown characteristics of the microporous substrate which is the base film.

Therefore, by using a porous substrate having excellent heat resistance as a base film and applying the shutdown coating layer of the present invention to it, it is possible to produce a separator having a low shutdown temperature, a high melt fracture temperature, and a low thermal contraction rate. There is an effect of greatly improving the thermal stability of the battery.

The porous coating membrane according to the present invention is characterized in that a shutdown coating layer comprising a polymer resin having a shutdown (Shut-down) property is applied to one or both surfaces of the microporous substrate. In this case, the microporous substrate used as the base film includes polyolefin, polyvinylidene fluoride, polysulfone, cellulose acetate, teflon, polyester, polyamide, polyimide film. In the present invention, a base film in a state in which the coating layer is not applied is referred to as a "porous substrate" for convenience, and a state in which the coating layer is coated on the porous substrate is referred to as a "porous coating membrane".

In the present invention, the shutdown coating layer is a coating slurry comprising 0.1 to 50 parts by weight of a polymer having a shutdown characteristic prepared by emulsion polymerization or suspension polymerization, 1 to 40 parts by weight of a binder resin, and 10 to 100 parts by weight of a dispersion solvent. It is formed by applying. The shutdown coating layer has a function of blocking the movement of ionic materials by dissolving when the temperature inside the battery increases above a certain temperature to close the pores in the separator.

And, the thickness of the shutdown coating layer is preferably 0.5 ~ 10㎛, if the thickness is less than 0.5㎛ can not impart a sufficient shutdown function of the coating separator, on the contrary, if it is 10㎛ or more, the air permeability is lowered, the whole membrane Too thick of the negatively affect the workability and size of the secondary battery assembly.

Examples of the polymer resin exhibiting the shutdown characteristics include (meth) acrylic copolymers, (meth) acryl-styrene copolymers, (meth) acryl-acrylonitrile copolymers, silicone- (meth) acrylic copolymers, and epoxy- ( Any one or more selected from a meta) acrylic copolymer, an ethylene copolymer, and a propylene copolymer can be used.

The polymer resin having the shutdown characteristic contributes to improving the heat resistance and physicochemical properties of the separator through various chemical modifications. Therefore, when the content of the polymer resin is less than 0.1 parts by weight, it may not exhibit sufficient shutdown characteristics in the microporous coating membrane. If the content is 50 parts by weight or more, the coating membrane may be insufficient due to lack of flexibility of the coating film, and there may be a decrease in fine cracks at low temperatures. There is a problem that can cause cracks. Moreover, it is preferable to use the polymer which has the said shutdown characteristic that a weight average molecular weight is 50,000-500,000, particle size is 0.01-1 micrometer, and melting | fusing point is 105-145 degreeC.

Next, as the binder resin, polyvinyl fluoride homopolymer (PVDF HOMO), polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP), polyvinylidene fluoride-trichloroethylene (PVDF-CTFE), acrylic Copolymer, methacrylic copolymer, (meth) acryl-styrene copolymer, (meth) acryl-acrylonitrile copolymer, silicone- (meth) acrylic copolymer, epoxy- (meth) acrylic copolymer, polybutadiene , Polyisoprene, butadiene-styrene copolymer, isoprene-styrene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene copolymer, styrene-butadiene-styrene Any one or more selected from ene copolymers may be used.

The binder resin not only serves to stably fix the polymer resin exhibiting the shutdown characteristic to the surface of the base film, but also provides flexibility to the shutdown coating layer. When the content is less than 1 part by weight, the binder resin exhibits the shutdown characteristic. The polymer or the inorganic filler may not be properly adhered to the base film. On the contrary, if the content is 40 parts by weight or more, the air permeability increases, which is not preferable.

Finally, the dispersion solvent is water, cyclopentane, cyclohexane, toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, acetonitrile, propionitrile, tetrahydrofuran, ethylene glycol diethyl ether Or at least one selected from methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether, N-methylpyrrolidone, and N, N-dimethylformamide.

The dispersion solvent is all volatilized during the drying process after coating the coating slurry on one or both sides of the porous substrate. Thus, the shutdown coating layer applied to the porous coating membrane of the present invention contains substantially no dispersion solvent.

If the content of the dispersion solvent is less than 10 parts by weight, the viscosity of the coating slurry is increased and the coating thickness is uneven, which is a problem in the manufacturing process, on the contrary, if the content is more than 99 parts by weight, the viscosity of the coating slurry is too low to uniformly distribute the components of the coating film. There is a risk of not being.

On the other hand, the method of manufacturing a porous coating membrane according to the present invention comprises the steps of (A) preparing a coating slurry (Coating slurry) comprising a polymer resin having a shutdown characteristic, and (B) the coating slurry on one or both sides of the porous substrate Coating to form a shutdown coating layer.

A) Preparation of Coating Slurry

First, the coating slurry used to form the shutdown coating layer is mixed with 0.1 to 50 parts by weight of a polymer having a shutdown characteristic prepared by emulsion polymerization or suspension polymerization, 1 to 40 parts by weight of a binder resin, and 10 to 100 parts by weight of a dispersion solvent. It is manufactured by. Here, the types of the polymer having the shutdown characteristic, the binder resin and the dispersion solvent are the same as described above, and thus redundant description is omitted.

However, when the manufacturing method of a (meth) acrylic-type copolymer is illustrated in the polymer resin which has the said shutdown characteristic, 0.1-10 weight part of hydroxyl-containing (meth) acrylic acid esters and C1-C4 of (meth) acrylic acid in presence of an emulsifier The monomer mixture which consists of 60-95 weight part of alkyl esters and 0.5-30 weight part of other unsaturated monomers copolymerizable with these unsaturated monomers can be manufactured by superposing | polymerizing by emulsion polymerization method or suspension polymerization method.

In addition, as the dispersion solvent, water or an organic solvent may be used as described above. When water is used as the dispersion solvent, there is no risk of generating volatile toxic substances during the drying process after coating, thereby enabling eco-friendly operation.

When the organic solvent is used as a dispersion solvent, the more the solvent having high solubility to the polymer is used, the higher the content of the polymer resin having the shutdown characteristic can be, and the coating slurry can maintain a stable dispersion state. In addition, the lower the boiling point, the easier it is to remove the dispersion solvent in the process of drying the coating film. It is preferable that the breaking point of the said dispersion solvent is 40-150 degreeC.

B ) Coating and drying of coating slurry

Next, the coating slurry prepared in step A) is applied to one or both surfaces of the microporous substrate with a thickness of 0.5 to 10 μm, and dried to form a shutdown coating layer. At this time, all of the dispersion solvent contained in the coating slurry is removed in the drying process. Therefore, the dispersion solvent does not remain in the shutdown coating layer.

The coating liquid may be coated using a conventional coating method, for example, dip coating, die coating, gravure coating, micro gravure coating, comma coating, or a combination thereof. Various methods, such as a mixing method, can be used.

In addition, a method of drying the shutdown coating layer may be a method of drying by hot air, hot air, vacuum drying, or irradiating far infrared rays or electron beams. In addition, the drying temperature is different depending on the type of the dispersion solvent, but when the drying at a temperature of 50 ~ 120 ℃ generally can remove the dispersion solvent completely.

Hereinafter, the present invention will be described in detail with reference to specific examples. However, the scope of the present invention is not limited by the following examples.

Example 1

One) shut down  Preparation of Polymer Having Properties

As the radical polymerizable monomer, 10 parts by weight of ethyl acrylate, 77 parts by weight of methyl methacrylate, 10 parts by weight of n-butyl methacrylate, 1 part by weight of acrylic acid, and 2 parts by weight of hydroxyethyl methacrylate are mixed thereto. 1 part by weight of alkyl sulfosuccinate (concentration 70%), 2 parts by weight sodium lauryl ether sulfate (concentration 33%), 3 parts by weight of disodium alkylethoxy sulfosuccinate (concentration 31%) and 50 parts by deionized water After the addition, the mixture was stirred in a homomixer to prepare the monomer-containing composition, which was added to a dropping tank.

Separately, 49 parts by weight of deionized water was added to a polymerization vessel equipped with a heating device, a stirrer, a reflux cooling device, a thermometer, a nitrogen introduction tube, and a dropping tank, and stirred under a nitrogen atmosphere to raise the internal temperature to 78 ° C., followed by solid content. 0.1 parts by weight of 3% aqueous potassium persulfate solution was added. After about 5 minutes had elapsed, the monomer-containing composition and 0.35 parts by weight of a 3% potassium persulfate aqueous solution were added dropwise over 4 hours from different dropping tanks as solids.

After completion of the dropping, the temperature was maintained at 80 ° C. for 30 minutes, and then, the internal temperature was set to 60 ° C. over 30 minutes, and then 0.1 parts by weight of t-butyl hydroperoxide and 0.12 parts by weight of Longgarit-C were added, followed by stirring again. The mixture was reacted for 30 minutes and neutralized with ammonia water to obtain a polymer aqueous dispersion having a shutdown characteristic and having a glass transition temperature of 75 ° C.

2) Manufacturing Method of Binder Resin

As a radically polymerizable monomer, 60 parts by weight of ethyl acrylate, 21 parts by weight of n-butyl methacrylate, 16 parts by weight of acrylonitrile, and 3 parts by weight of methacrylic acid were mixed, and sodium dialkyl sulfosuccinate (concentration 70%) was added thereto. 1 part by weight, 2 parts by weight of sodium lauryl ether sulfate (concentration 33%), 3 parts by weight of disodium alkylethoxy sulfosuccinate (concentration 31%) and 50 parts by weight of deionized water were added, followed by stirring in a homomixer. The monomer-containing composition was prepared, and this was put into a dropping tank.

Separately, 49 parts by weight of deionized water was added to a polymerization vessel equipped with a heating device, a stirrer, a reflux cooling device, a thermometer, a nitrogen introduction tube, and a dropping tank, and stirred under a nitrogen atmosphere to raise the internal temperature to 78 ° C., followed by solid content. 0.1 parts by weight of 3% aqueous potassium persulfate solution was added. After about 5 minutes had elapsed, the monomer-containing composition and 0.35 parts by weight of a 3% potassium persulfate aqueous solution were added dropwise over 4 hours from different dropping tanks as solids.

After completion of the dropwise addition, the mixture was kept at a temperature of 80 ° C. for 30 minutes, and then the internal temperature was set to 60 ° C. over 30 minutes to add 0.1 parts by weight of t-butyl hydroperoxide and 0.12 parts by weight of Longgarit-C, followed by stirring again. The reaction is 30 minutes and neutralized with ammonia water to obtain a polymer aqueous dispersion having a glass transition temperature (Tg) of -14 ℃ while having a shutdown characteristic.

3) Coating slurry  Produce

30 parts by weight of the polymer having the shutdown characteristics prepared in step 1), 10 parts by weight of the binder resin prepared in step 2), and 60 parts by weight of water are mixed and uniformly dispersed by using a ball mill and a bead mill. Coating slurry was prepared.

4) shut down  Formation of coating layer

The coating slurry prepared in step 3) was gravure coated on both sides of a polyethylene-based microporous substrate having a thickness of 20 μm, and dried by hot air at a temperature of 80 ° C. for 5 minutes to form a shutdown coating layer. In this case, the thickness of the shutdown coating layer is shown in Table 1 below.

[Example 2]

10 parts by weight of ethyl acrylate, 47 parts by weight of methyl methacrylate, 30 parts by weight of acrylonitrile, 10 parts by weight of n-butyl methacrylate, 1 part by weight of acrylic acid, as a radical polymerizable monomer in step 1) of Example 1 A porous coating membrane was prepared in the same manner as in Example 1, except that a polymer aqueous dispersion having a glass transition temperature of 73 ° C. was prepared using 2 parts by weight of hydroxyethyl methacrylate.

[Example 3]

As a radically polymerizable monomer in step 1) of Example 1, 10 parts by weight of ethyl acrylate, 72 parts by weight of methyl methacrylate, 5 parts by weight of acamide, 10 parts by weight of n-butyl methacrylate, 1 part by weight of acrylic acid, and A porous coating membrane was prepared in the same manner as in Example 1, except that a polymer aqueous dispersion having a glass transition temperature of 77 ° C. having a shutdown characteristic using 2 parts by weight of oxyethyl methacrylate was prepared.

Example 4

In step 1) of Example 1, 40 parts by weight of ethyl acrylate, 472 parts by weight of methyl methacrylate, 10 parts by weight of n-butyl methacrylate, 1 part by weight of acrylic acid, and hydroxyethyl methacrylate 2 as a radical polymerizable monomer. A porous coating membrane was prepared in the same manner as in Example 1, except that a polymer aqueous dispersion having a glass transition temperature of 33 ° C. having a shutdown characteristic using parts by weight was prepared.

Comparative Example 1

A conventional polyethylene-based porous substrate having a thickness of 20 μm and without applying a shutdown coating layer was used as a separator.

Comparative Example 2

A porous coating membrane was prepared in the same manner as in Example 1, except that the coating slurry without the polymer exhibiting the shutdown characteristic was used in Example 1.

[Comparative Example 3]

A coating separator was prepared in the same manner as in Example 1, except that the coating slurry without the binder resin was used in Example 1.

Test result

Samples were taken for each of the separators prepared according to Examples and Comparative Examples, their physical properties were measured, and the results are summarized in Tables 1 and 2.

Test Item (Unit) Example 1 Example 2 Example 3 Example 4 Thickness (㎛) 24.9 25.0 25.1 24.8 Air permeability (sec / 100ml) 330.5 356.2 385.8 344.0 Tensile strength (kgf / cm2) 2301 2290 2260 2295 Penetration Strength (Kgf / ㎠) 790.2 795.6 800.9 802.3 Shutdown temperature Start (℃) 123 125 130 103 End (℃) 123 128 129 100 Heat shrinkage (%); 120 ℃ / 60 minutes Portrait orientation (MD) 2.0 3.8 5.0 8.0 Landscape (TD) 2.0 2.2 4.1 7.5 Impedence magnitude (Ω) 3.5 4.1 3.8 4.4

Test Item (Unit) Comparative Example 1 Comparative Example 2 Comparative Example 3 Thickness (㎛) 20.0 26.0 26.1 Air permeability (sec / 100ml) 285 391 ∞ Tensile strength (kgf / cm2) 2260 2195 2234 Penetration Strength (Kgf / ㎠) 799 782 789 Shutdown temperature Start (℃) 145 144 145 End (℃) 147 148 145 Heat shrinkage (%); 120 ℃ / 60 minutes Portrait orientation (MD) 3.0 3.2 4.5 Landscape (TD) 3.0 3.0 4.3 Impedence magnitude (Ω) 3.8 4.5 6.0

Test Methods

Test methods for the test items of Table 2 and Table 3 are as follows.

1) heat shrinkage (%); Using a separator prepared according to the above Examples and Comparative Examples to prepare a sample having a horizontal and vertical size of 10 x 10 Cm, sandwich the sample between A4 paper and put it in an oven, and then left for 60 minutes at a temperature of 120 ℃ After shrinkage was measured.

2) breathability (sec / 100ml); A sample having a size of 30 × 30 mm was taken with respect to the separator, and the time required for passage of 100 ml of air was measured using a Toyoseiki air permeability meter.

3) tensile strength (Kgf / cm 2); Samples each having a size of 20 x 200 mm in the MD and TD directions were taken with respect to the separator, and the force applied until the sample was broken using an Instron tensile strength tester was measured.

4) puncture strength (Kgf / cm 2); A sample having a size of 100 x 50 mm was taken with respect to the separator, and the force applied until the sample was punctured when a force was applied using a stick using a Katotech piercing strength meter was measured.

5) Impedance Magnitude (Ω); The separator is cut into a diameter of 16 mm, impregnated with electrolyte for 30 seconds, and a stainless steel lead is connected to an electrode of an impedance analyzer. After attaching to the electrode of the impedance analyzer and contacting both sides of the separator, the surface of the material used in the pouch cell (Pouch cell) was in close contact with each other, and the impedance was measured.

Comparison of physical properties

As can be seen from the results of Table 1 and Table 2, the coating separator prepared according to the embodiment of the present invention has a shutdown temperature of 130 ° C. or less, and Comparative Example 1 or a polymer exhibiting shutdown characteristics without any coating. It was confirmed that there is an effect that the shutdown temperature is lowered by 15 ° C or more as compared with Comparative Example 2 which is not used.

In addition, it can be seen from the results of the above example that when the polymer exhibiting the shutdown characteristic is blended, it is possible to control the shutdown temperature of the shutdown coating layer by adjusting the glass transition temperature (Tg) of the copolymer.

Claims (12)

One or both surfaces of the microporous substrate are coated with a shutdown coating layer including a polymer resin having a shut-down characteristic. The polymer having the shutdown characteristic has a weight average molecular weight of 50,000 to 500,000 and a particle size of 0.01 to 1 Porous coating membrane, characterized in that the μm.
The coating according to claim 1, wherein the shutdown coating layer comprises 0.1 to 50 parts by weight of a polymer having a shutdown characteristic by emulsion polymerization or suspension polymerization, 1 to 40 parts by weight of a binder resin, and 10 to 100 parts by weight of a dispersion solvent. Porous coating membrane, characterized in that formed by applying a slurry.
The porous coating membrane of claim 1 or 2, wherein the shutdown coating layer has a thickness of 0.5 to 10 [mu] m.
The polymer according to claim 1 or 2, wherein the polymer having a shutdown characteristic is a (meth) acrylic copolymer, a (meth) acryl-styrene copolymer, a (meth) acryl-acrylonitrile copolymer, or a silicone- (meth A porous coating membrane, characterized in that any one or more selected from an acrylic copolymer, an epoxy- (meth) acrylic copolymer, an ethylene copolymer, and a propylene copolymer.
delete The porous coating membrane of claim 1 or 2, wherein the polymer having the shutdown characteristic has a melting point of 105 to 145 ° C.
The method of claim 1 or 2, wherein the microporous substrate is composed of any one or more selected from polyolefin, polyvinylidene fluoride, polysulfone, cellulose acetate, teflon, polyester, polyamide, polyimide film Porous coating membrane.
The method of claim 2, wherein the binder resin is polyvinyl fluoride homopolymer, polyvinylidene fluoride-hexafluoro propylene, polyvinylidene fluoride-trichloroethylene, acrylic copolymer, methacrylic copolymer, (meth) Acrylic-styrene copolymer, (meth) acryl-acrylonitrile copolymer, silicone- (meth) acrylic copolymer, epoxy- (meth) acrylic copolymer, polybutadiene, polyisoprene, butadiene-styrene copolymer, At least one selected from isoprene-styrene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene copolymer, and styrene-butadiene-styrene copolymer Porous coating membrane.
A) preparing a coating slurry by mixing 0.1 to 50 parts by weight of a polymer having a shutdown characteristic prepared by emulsion polymerization or suspension polymerization, 1 to 40 parts by weight of a binder resin, and 10 to 100 parts by weight of a dispersion solvent;
B) applying the coating slurry on one or both sides of the porous substrate to a thickness of 0.5 ~ 10㎛ and dried to form a shutdown coating layer;
Method for producing a porous coating membrane comprising a.
10. The polymer according to claim 9, wherein the polymer having the shutdown characteristic is a (meth) acrylic copolymer, a (meth) acryl-styrene copolymer, a (meth) acryl-acrylonitrile copolymer, or a silicon- (meth) acrylic air Porous coating membrane, characterized in that any one or more selected from among copolymer, epoxy- (meth) acrylic copolymer, ethylene copolymer, and propylene copolymer.
The method according to claim 10, wherein the (meth) acrylic copolymer is 0.1 to 10 parts by weight of hydroxyl group-containing (meth) acrylic acid ester in the presence of an emulsifier, 60 to 95 parts by weight of alkyl ester having 1 to 4 carbon atoms of (meth) acrylic acid, and A porous coating membrane prepared by polymerizing a monomer mixture composed of 0.5 to 30 parts by weight of other unsaturated monomers copolymerizable with these unsaturated monomers by emulsion polymerization or suspension polymerization.
The method of claim 9 or 10, wherein the dispersion solvent is water, cyclopentane, cyclohexane, toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, acetonitrile, propionitrile, tetra At least one selected from hydrofuran, ethylene glycol diethyl ether, methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether, N-methylpyrrolidone, and N, N-dimethylformamide. Porous coating membrane.