KR102287723B1 - A coating composition for a separator and a method for manufacturing a separator using the same - Google Patents

Abstract

One aspect of the present invention provides a separator coating composition comprising inorganic particles, a polymer binder, a dispersant, and a persulfate-based compound and water, and a method for manufacturing a separator using the same.

Description

Separator coating composition and method for manufacturing a separation membrane using the same

The present invention relates to a separator coating composition and a method for manufacturing a separator using the same.

Lithium secondary batteries are widely used as a power source for various electric products that require miniaturization and weight reduction, such as smartphones, laptops, and tablet PCs. The development of large, long-life, and high-stability lithium secondary batteries is required.

In order to improve the stability, a separator with micropores is used to separate the positive electrode and the negative electrode to prevent an internal short circuit and to facilitate the movement of lithium ions during the charging and discharging process. Polyolefin-based polyethylene or polypropylene is used as the furnace.

When the separator is exposed to a high-temperature environment due to the non-ideal behavior of the battery, mechanical shrinkage or damage of the separator may occur. In order to overcome this problem, a technology for securing the stability of the battery by suppressing the thermal contraction of the separator is required. In particular, as the market expands from small batteries to medium and large batteries, the stability standards required for separators have been raised. It is known how to raise it. However, the separation membranes manufactured in the prior art cannot secure the desired adhesiveness, and it is difficult to apply them collectively to the separation membranes having various shapes and sizes. Therefore, it is necessary to develop a separator having high heat resistance and excellent adhesion at the same time.

In addition, according to the composition of the coating layer, it can be divided into an aqueous coating separator and a non-aqueous coating separator, and the aqueous coating separator has a low binding force between the separator substrate and the coating layer interface, so that the coating layer is easy to detach, and foreign substances such as dust during slitting This may occur, and the foreign material may cause problems such as poor appearance of the battery.

In addition, since lithium contained in a secondary battery may explode due to a rapid reaction upon contact with moisture, a separator using an aqueous slurry needs to reduce the moisture content in order to prevent such an explosion accident. Accordingly, when the content of the binder included in the coating layer is increased to improve the peel strength of the coating layer with respect to the separator substrate, increasing the content of the binder is an appropriate solution because the resistance of the separator is increased and the ventilation time is also increased. this is not happening

In order to solve the safety problem of the battery, Korean Patent Application Laid-Open No. 10-2009-0130885 discloses a multilayer porous membrane structure having a porous layer including an inorganic filler by applying a methacrylic acid ester-acrylic acid ester copolymer as a binder. presented. However, with the composition presented in the above patent, thermal and physical stability of the battery, particularly, electrolyte resistance, is weak when coating with a coating thickness of 4 μm or less based on the cross-section of the coating, so coating layer delamination due to electrolyte swelling occurs. , it was difficult to secure durability and reliability.

The present invention is to solve the problems of the prior art described above, and an object of the present invention is to increase the binding force between the separator substrate and the coating layer interface to suppress the detachment of the coating layer, and thus a separator coating composition with improved heat resistance and a separator using the same To provide a manufacturing method of

One aspect of the present invention provides a membrane coating composition comprising inorganic particles, a polymer binder, a dispersant, and a persulfate-based compound and water.

In one embodiment, the content of the inorganic particles in the separation membrane coating composition may be 20 to 40% by weight.

In one embodiment, the average particle size of the inorganic particles may be 0.1 ~ 10㎛.

In one embodiment, the inorganic particles are SiO ₂ , AlOOH, Mg(OH) ₂ , Al(OH) ₃ , TiO ₂ , BaTiO ₃ , Li ₂ O, LiF, LiOH, Li ₃ N, BaO, Na ₂ O , Li ₂ CO ₃ , CaCO ₃ , LiAlO ₂ , Al ₂ O ₃ , SiO, SnO, SnO ₂ , PbO ₂ , ZnO, P ₂ O ₅ , CuO, MoO, V ₂ O ₅ , B ₂ O ₃ , Si ₃ It may be one selected from the group consisting of _{N 4} , CeO ₂ , Mn ₃ O ₄ , Sn ₂ P ₂ O ₇ , Sn ₂ B ₂ O ₅ , Sn ₂ BPO _{6 , and combinations of two or more thereof.}

In one embodiment, the content of the polymer binder in the separator coating composition may be 1 to 10% by weight.

In one embodiment, the polymer binder is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylonitrile , polyvinylpyrrolidone, polyvinyl acetate, ethylene vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyano Noethyl cellulose, hydroxyethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, acrylonitrile-acrylic acid copolymer, ethylene-acrylic acid copolymer, styrene-butadiene copolymer It may be one selected from the group consisting of a copolymer, an alkyl acrylate-acrylonitrile copolymer, polyethylene glycol, an acrylic rubber, and a combination of two or more thereof.

In one embodiment, the content of the dispersant in the separator coating composition may be 0.1 to 5% by weight.

In one embodiment, the dispersant may be sodium metaphosphate, sodium hexametaphosphate, or a combination thereof.

In one embodiment, the content of the persulfate-based compound in the separator coating composition may be 0.1 to 10% by weight.

In an embodiment, the persulfate-based compound may be metal persulfate, ammonium persulfate, or a combination thereof.

Another aspect of the present invention comprises the steps of: (a) processing a composition comprising a polyolefin and a pore former to prepare a porous support; And (b) coating the separator coating composition on at least one surface of the porous support and drying at 50 to 100° C. for 0.5 to 10 minutes to form a coating layer; provides a method for producing a separator comprising.

The separator coating composition according to an aspect of the present invention includes inorganic particles, a polymer binder, a dispersant, and a persulfate compound and water, and in particular, by including a persulfate compound as an initiator for crosslinking the polymer binder, Desorption of the coating layer can be suppressed by increasing the binding force between the separator substrate and the interface of the coating layer, and thus the heat resistance of the separator can be improved.

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

Hereinafter, the present invention will be described. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein.

Throughout the specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another member interposed therebetween. . In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

Separator coating composition

One aspect of the present invention provides a membrane coating composition comprising inorganic particles, a polymer binder, a dispersant, and a persulfate-based compound and water. The separator coating composition may be coated and dried (cured) on at least one surface of the porous support constituting the separator to form a coating layer, and water contained in the coating composition is removed during drying. That is, the coating layer may include inorganic particles, a polymer binder, a dispersant, and a persulfate-based compound.

The content of the inorganic particles in the separator coating composition may be 20 to 40% by weight. If the content of the inorganic particles in the separator coating composition is less than 20% by weight, the required level of heat resistance cannot be imparted, and if it exceeds 40% by weight, the dispersibility of the inorganic particles may decrease or workability and processability may decrease during slurry coating. there is.

The average particle size of the inorganic particles may be 0.1 to 10㎛. If the average particle size of the inorganic particles is less than 0.1 μm, the inorganic particles may arbitrarily agglomerate to reduce dispersibility, and a required level of heat resistance may not be provided. In addition, when the average particle size of the inorganic particles is greater than 10 μm, the separator may become thick, thereby inhibiting downsizing and integration of the battery or device.

The inorganic particles are SiO ₂ , AlOOH, Mg(OH) ₂ , Al(OH) ₃ , TiO ₂ , BaTiO ₃ , Li ₂ O, LiF, LiOH, Li ₃ N, BaO, Na ₂ O, Li ₂ CO ₃ , CaCO ₃ , LiAlO ₂ , Al ₂ O ₃ , SiO , SnO, SnO ₂ , PbO ₂ , ZnO, P ₂ O ₅ , CuO, MoO, V ₂ O ₅ , B ₂ O ₃ , Si ₃ N ₄ , CeO ₂ , one selected from the group consisting of Mn ₃ O ₄ , Sn ₂ P ₂ O ₇ , Sn ₂ B ₂ O ₅ , Sn ₂ BPO ₆ and combinations of two or more thereof, preferably an oxide, more preferably AlOOH and/ or Al ₂ O ₃ , advantageously, AlOOH, but not limited thereto.

When the inorganic particles are plate-shaped AlOOH, the surface portion of the AlOOH particle has a (-) charge and the edge portion has a (+) charge. tends to agglomerate. Aggregation of these inorganic particles may impair the uniformity of physical properties on the surface of the separation membrane.

In this regard, the coating composition may further include an additive for improving the dispersibility of the inorganic particles, for example, a dispersant, a surfactant, and the like. In particular, the coating composition may include sodium metaphosphate (NaPO ₃ ), sodium hexametaphosphate ((NaPO ₃ ) ₆ ), or a combination thereof as a dispersant, and the content of the dispersant in the separator coating composition is 0.1 to 5% by weight, preferably 0.1 to 3% by weight, more preferably 0.01 to 1% by weight.

In particular, the sodium hexametaphosphate is adsorbed to the edge of the AlOOH particle to weaken the negative charge of the edge, thereby effectively preventing the AlOOH particle from aggregating, as well as the storage stability of the coating composition, as well as in the coating layer. It is possible to improve the dispersibility of the inorganic particles.

The polymer binder is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylonitrile, polyvinylpyrrolidone , polyvinyl acetate, ethylene vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, Hydroxyethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, acrylonitrile-acrylic acid copolymer, ethylene-acrylic acid copolymer, styrene-butadiene copolymer, alkyl acrylate- It may be one selected from the group consisting of acrylonitrile copolymer, polyethylene glycol, acrylic rubber, and a combination of two or more thereof, and preferably, carboxymethyl cellulose and/or alkyl acrylate-acrylonitrile copolymer, The present invention is not limited thereto.

The content of the polymer binder in the separator coating composition may be 1 to 10% by weight. If the content of the polymer binder in the separator coating composition is less than 1% by weight, the binding force between the inorganic particles and between the coating layer and the porous support may be reduced, and if it exceeds 10% by weight, the content of the inorganic particles is relatively reduced Therefore, the heat resistance of the separator may be reduced.

The persulfate-based compound may act as an initiator to generate radicals in the polymer chains of the polymer binder included in the coating composition so that these chains are cross-linked.

As used herein, the term “persulfate compound” _{refers to a compound containing SO 5} ^2- and/or S ₂ O ₈ ^2- ions, and is also referred to as peroxysulfate or peroxodisulfate.

The content of the persulfate-based compound in the separator coating composition may be 0.1 to 10% by weight. If the content of the persulfate-based compound in the separator coating composition is less than 0.1% by weight, the binding force between the inorganic particles and between the coating layer and the porous support may be reduced, and if it exceeds 10% by weight, flexibility and tensile properties of the separator , the air permeability may be lowered.

The persulfate-based compound may be a metal persulfate, ammonium persulfate, or a combination thereof, and the metal persulfate is, for example, an alkali metal persulfate such as potassium persulfate and sodium persulfate, aluminum persulfate, etc. However, the present invention is not limited thereto.

Separation Membrane Manufacturing Method

Another aspect of the present invention comprises the steps of: (a) processing a composition comprising a polyolefin and a pore former to prepare a porous support; And (b) coating the separator coating composition on at least one surface of the porous support and drying at 50 to 100° C. for 0.5 to 10 minutes to form a coating layer; provides a method for producing a separator comprising.

In step (a), _{a composition comprising a polyolefin having a weight average molecular weight (M w} ) of 250,000 to 1,000,000 and a pore former is put into an extruder, extruded, and discharged through a T-die to form a sheet, followed by stretching Thus, a porous support can be prepared.

The polyolefin may be one selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acetate, ethylene butyl acrylate, ethylene ethyl acrylate, and combinations or copolymers of two or more thereof, and preferably, polyethylene, but It is not limited.

The composition may include 20 to 40 parts by weight of the polyolefin and 60 to 80 parts by weight of the pore former. The pore former may be extracted and removed from the inside of the support by a wet method using thermally induced phase separation to form pores.

In the wet method, the support including the pore-forming agent may be immersed in an extraction tank in which a solvent is supported. The extraction temperature may be 15 to 80° C., preferably 25 to 40° C., and the extraction time may be 0.1 to 60 minutes, preferably 1 to 20 minutes.

The pore-forming agent is, for example, paraffin oil, paraffin wax, mineral oil, solid paraffin, soybean oil, rapeseed oil, palm oil, palm oil, di-2-ethylhexyl phthalate, dibutyl phthalate, diisononyl phthalate, diisodecyl phthalate , may be one selected from the group consisting of bis(2-propylheptyl)phthalate, naphthenoyl, and combinations of two or more thereof, preferably paraffin oil, and more preferably, a kinematic viscosity of 50~ It may be 100 cSt paraffin oil, but is not limited thereto.

The solvent for extracting the pore former may be one selected from the group consisting of pentane, hexane, benzene, dichloromethane, carbon tetrachloride, methyl ethyl ketone, acetone, and a combination of two or more thereof, preferably, dichloromethane However, the present invention is not limited thereto.

In step (b), the separator coating composition is coated on at least one surface of the porous support and dried at 50 to 100° C. to form a coating layer.

The coating may be performed by applying the separator coating composition to a dip coating, a die coating, a roll coating, a bar coating, a comma coating, or a combination of two or more thereof. It may be made in a manner to collectively remove the solvent and other liquid residues contained in the coating composition by batch coating and then drying.

In addition, the coating may be made by phase separation. The coating composition may include inorganic particles and a binder, and the binder may be a gel polymer. In addition, it may be understood that the inorganic particles do not substantially affect the phase separation since they are not dissolved in a solvent serving as a dispersion medium in the coating composition.

In the separation membrane formed with a coating layer including a plurality of open three-dimensional pores connected to each other on the porous support, when a nonsolvent is added to the gel polymer solution, a part of the solvent is substituted with the nonsolvent, so that the gel polymer-rich phase and the gel polymer It can also be prepared using phase separation into a depleted phase.

When pores are formed in the gel polymer using a plasticizer as disclosed in US Patent No. 5,460,904, the position of the plasticizer for forming pores is not flexible, so that closed pores are formed.

On the other hand, the present invention relates to a phase separation of a solvent/non-solvent phase, that is, a liquid-liquid phase separation phenomenon, into a gel polymer-rich phase and a gel polymer-depleted phase, and a gel polymer-deficient phase, which is a liquid phase to form pores. Since the (phase) is fluid and pore growth is possible by excess Gibbs free energy, it is possible to provide a coating layer having a three-dimensional open-porous structure in which pores are connected.

In addition, in step (b), the separator coating composition may be dried at 50-100° C. for 0.5-10 minutes to cross-link the polymer binder included in the separator coating composition. Specifically, under the temperature conditions in the above range, the persulfate-based compound included in the separator coating composition may generate radicals in at least some regions of the polymer chains of the polymer binder so that these chains are cross-linked. If the drying temperature is less than 50 ° C., the polymer binder is not crosslinked properly, so the required level of binding force cannot be implemented. .

Meanwhile, before step (b), the porous support may be plasma-treated in the presence of a mixed gas containing _{sulfur dioxide (SO 2} ) and oxygen (O _{2 ).}

By making the surface of the support and/or the surface of the internal pores hydrophilic through the plasma treatment, the bonding force between the support and the slurry can be improved, thereby significantly improving the durability of the separator, in particular, long-term durability and heat resistance. can

Conventionally, in order to hydrophilize the surface of the support, a wet process in which the support is immersed in sulfuric acid for a certain period of time to sulfonate it has been mainly used, but in this case, the wet process is preceded or followed by plasma treatment. There is a problem in that the process is complicated and a large amount of process waste is generated.

In contrast, since the process gas used in the plasma treatment includes a certain amount of sulfur dioxide gas as well as the conventional air, oxygen and/or inert gas, a single process called the plasma treatment is performed without a wet process such as immersing the support in sulfuric acid or the like. _{A functional group such as -SO 3} is generated on the surface of the support and the surface of the internal pores through a dry process, that is, sulfonated to maximize the hydrophilicity and ionic conductivity of the support, and the conventional complex process can be simplified, and it is also advantageous from an environmental point of view.

The mixed gas, which is a process gas used in the plasma treatment, is 50 to 90 vol% of sulfur dioxide and 10 to 50 vol% of oxygen, preferably 60 to 80 vol% of sulfur dioxide and 20 to 40 vol% of oxygen, more preferably, It may contain 70 to 80% by volume of sulfur dioxide and 20 to 30% by volume of oxygen. If the content of sulfur dioxide in the mixed gas is less than 50% by volume, the hydrophilicity required for the support may not be implemented, and if it exceeds 90% by volume, the process may be unstable.

The plasma treatment may be performed for 0.5 to 90 minutes, preferably, 0.5 to 20 minutes. When the plasma treatment is performed for less than 0.5 minutes, the support cannot be hydrophilized or sulfonated to a required level, and when it is performed for more than 90 minutes, the hydrophilicity and sulfonation degree converge to a certain level, thereby reducing process efficiency.

Hereinafter, embodiments of the present invention will be described in detail.

manufacturing example

30 parts by weight of high-density polyethylene (HDPE) having a weight average molecular weight (Mw) of 350,000 and a molecular weight distribution (Mw/Mn) of 5 and 70 parts by weight of paraffin oil having a kinematic viscosity of 70 cSt at 40 ° C. , L/D=56). After discharging from the twin-screw extruder to a T-die having a width of 300 mm at a screw rotation speed of 40 rpm and 200 ° C., it was passed through a casting roll having a temperature of 40 ° C. A base sheet was prepared.

The base sheet was stretched 6 times in the longitudinal direction (MD) in a roll stretching machine at 110° C., and stretched 7 times in the transverse direction (TD) in a tenter stretching machine at 125° C. to prepare a film. The film was impregnated in a dichloromethane leaching tank at 25° C. to extract and remove paraffin oil for 1 minute, and dried at 50° C. for 5 minutes to prepare a porous film.

Thereafter, 10% relaxation in the transverse direction (TD) at 130° C. was performed to prepare a porous support having a thickness and air permeability of 14 μm and 170 sec/100 ml, respectively.

Example 1

92 wt% of boehmite (AlOOH) having an average particle size of 1.5 μm, 7 wt% of acryl-acrylonitrile copolymer binder, and 1 wt% of a dispersant (sodium hexametaphosphate, (NaPO ₃ ) ₆ ) and distilled water were mixed in a weight ratio of 32:68, respectively, and then dispersed with a ball-mill to prepare an aqueous coating composition, and ammonium persulfate (APS, (NH ₄ ) ₂ S ₂ O ₈ ) as an initiator for the initiation reaction was added to the solid content of 100 wt. 0.5 part by weight was added with respect to the part.

The coating composition was coated on one surface of the porous support obtained in Preparation Example to a thickness of 2 μm based on the cross-section using a bar coating method, and dried at a temperature of 50° C. in a hot air oven to prepare a separator with a coating layer .

Example 2

A separator was prepared in the same manner as in Example 1, except that the drying temperature in the hot air oven was changed to 60°C.

Example 3

A separator was prepared in the same manner as in Example 1, except that the drying temperature in the hot air oven was changed to 70°C.

Example 4

A separation membrane was prepared in the same manner as in Example 1, except that the amount of ammonium persulfate was changed to 2 parts by weight based on 100 parts by weight of the solid content.

Example 5

A separator was prepared in the same manner as in Example 4, except that the drying temperature in the hot air oven was changed to 60°C.

Example 6

A separator was prepared in the same manner as in Example 4, except that the drying temperature in the hot air oven was changed to 70°C.

Example 7

A separation membrane was prepared in the same manner as in Example 1, except that the amount of ammonium persulfate was changed to 10 parts by weight based on 100 parts by weight of the solid content.

Example 8

A separator was prepared in the same manner as in Example 7, except that the drying temperature in the hot air oven was changed to 60°C.

Example 9

A separator was prepared in the same manner as in Example 7, except that the drying temperature in the hot air oven was changed to 70°C.

Comparative Example 1

92 wt% of boehmite (AlOOH) having an average particle size of 1.5 μm, 7 wt% of acryl-acrylonitrile copolymer binder, and 1 wt% of a dispersant (sodium hexametaphosphate, (NaPO ₃ ) ₆ ) and distilled water were mixed in a weight ratio of 32:68, respectively, and then dispersed with a ball-mill to prepare an aqueous coating composition.

The coating composition was coated on one surface of the porous support obtained in Preparation Example to a thickness of 2 μm based on the cross-section using a bar coating method, and dried at a temperature of 50° C. in a hot air oven to prepare a separator with a coating layer .

Comparative Example 2

55.5 parts by weight of ethyl acrylate (EA), 15 parts by weight of acrylonitrile (AN), 20 parts by weight of N,N-dimethylacrylamide (DMAAm) in a 1L reactor in which nitrogen gas is refluxed and a cooling device is installed for easy temperature control A monomer mixture comprising parts by weight, 5 parts by weight of 2-(dimethylamino)ethyl acrylate (DMAEA), 4 parts by weight of 4-hydroxybutyl acrylate (HBA), and 0.5 parts by weight of acrylic acid (AA) is added, followed by a solvent 100 parts by weight of acetone was added thereto.

Thereafter, nitrogen gas was purged for 1 hour to remove oxygen, and then the temperature was maintained at 50°C. Then, 0.03 parts by weight of azobisisobutyronitrile (AIBN) as an initiator and 0.05 parts by weight of normaldodecylmercaptan (DDM) as a polymerization regulator were added, followed by reaction for 24 hours. After completion of the reaction, the reaction product was diluted with acetone to prepare an acrylic copolymer having a solid concentration of 25% by weight and a weight average molecular weight of 330,000 g/mol.

100 parts by weight of the acrylic copolymer and 6.8 parts by weight of tolylene diisocyanate adduct as an isocyanate-based crosslinking agent were dissolved in 1,674 parts by weight of acetone to prepare a 6% by weight binder polymer solution.

By mixing 13 parts by weight of the prepared binder polymer solution and _{15 parts by weight of Al 2} O ₃ as inorganic particles, a slurry having a weight ratio of binder polymer/inorganic particles = 5/95 was prepared, and a polyethylene porous membrane having a thickness of 12 μm was prepared by dip coating. (porosity 45% by volume) was coated on both sides, and cured and dried in a drying oven at 80° C. for 10 minutes. Finally, the thickness of the coating layer formed on one surface was adjusted to be about 2㎛ a separator was prepared.

Comparative Examples 3 to 10

Acrylic copolymers of Comparative Examples 3 to 10 were prepared in the same manner as in Comparative Example 2 using the monomers shown in Table 1 below. The weight average molecular weight (Mw) of the copolymer thus prepared is as shown in Table 1 below, and the indicated numerical value represents parts by weight.

division comparative example
3 comparative example
4 comparative example
5 comparative example
6 comparative example
7 comparative example
8 comparative example
9 comparative example
10 DMAAm 20 35 30 24 24 35 35 35 AN 10 15 10 15 15 15 15 15 DMAEA 20 - 5 - 10 10 4 4 DMAPA - 5 - - - - - - AA 1.5 0.5 One - - 2 0.5 - HBA 8 4 One 4 4 - 15 - EA 40.5 35.5 38 57 47 38 30.5 46 BA - 5 5 - - - - - Mw 180,000 300,000 290 thousand 310,000 200,000 200,000 310,000 310,000

-DMAPA: 3-dimethylaminopropyl acrylate (3-dimethylaminopropyl acrylate)

-BA: n-butyl acrylate

A separator was prepared in the same manner as in Comparative Example 2, except that the slurry of the composition shown in Table 2, drying temperature, and time were applied.

division comparative example
3 comparative example
4 comparative example
5 comparative example
6 comparative example
7 comparative example
8 comparative example
9 comparative example
10 Binder content
(parts by weight) 5 5 5 5 5 5 5 5 inorganic particle content
(parts by weight) 95 95 95 95 95 95 95 95 Crosslinking agent content
(Compared to 100 parts by weight of the binder, parts by weight) 10 6.8 2 6.8 6.8 5 10 0 Drying temperature (℃) 70 80 70 80 80 100 70 70 Drying time (min) 5 5 15 10 60 15 5 5

Experimental Example 1

After cutting the separators prepared in Examples and Comparative Examples to a length of 180mm and a width of 15mm, attaching a tape to the surface of the separator, and then using Shimazu's UTM to connect the interface between the coating layer and the porous support at a tensile speed of 0.3m/min. After peeling, binding force (gf/15mm) was measured, and the average value measured five times for each specimen is shown in Table 3 below.

division Binding force (gf/15mm) Example 1 103.3 Example 2 104.2 Example 3 121.1 Example 4 102.1 Example 5 114.6 Example 6 117.3 Example 7 107.2 Example 8 103.0 Example 9 103.7 Comparative Example 1 96.7 Comparative Example 2 42.0 Comparative Example 3 32.0 Comparative Example 4 34.0 Comparative Example 5 37.0 Comparative Example 6 38.0 Comparative Example 7 38.0 Comparative Example 8 36.0 Comparative Example 9 < 15 Comparative Example 10 35.0

Experimental Example 2

The separation membranes prepared in Examples and Comparative Examples were prepared with a length (MD direction) of 200 mm and a width (TD direction) of 200 mm, and the sample was placed between A4 papers and placed in a convection oven, and then at 130°C for 1 hour. After standing, the thermal contraction rate was calculated using the following formula, and the thermal water rate of the separator is shown in Table 4 below.

Heat shrinkage (%) = {(A2-A1) / A2} * 100

(A2: area of the specimen before shrinkage (cm ² ), A1: area of the specimen after shrinkage (cm ² ))

division MD direction TD direction Example 1 1.1 0.7 Example 2 1.4 0.8 Example 3 1.3 0.5 Example 4 1.3 0.8 Example 5 1.5 0.7 Example 6 1.0 0.5 Example 7 1.6 1.0 Example 8 1.6 0.9 Example 9 2.0 1.1 Comparative Example 1 2.5 1.9

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

Claims (11)

In the separator coating composition comprising inorganic particles, a polymer binder, a dispersing agent, and water and a persulfate-based compound that generates radicals in the polymer chains of the polymer binder so that the polymer chains are cross-linked,
The content of the persulfate-based compound in the separator coating composition is 0.1 to 10% by weight, the separator coating composition. According to claim 1,
The content of the inorganic particles in the separator coating composition is 20 to 40% by weight, the separator coating composition. According to claim 1,
The average particle size of the inorganic particles is 0.1 ~ 10㎛, the separator coating composition. According to claim 1,
The inorganic particles are SiO ₂ , AlOOH, Mg(OH) ₂ , Al(OH) ₃ , TiO ₂ , BaTiO ₃ , Li ₂ O, LiF, LiOH, Li ₃ N, BaO, Na ₂ O, Li ₂ CO ₃ , CaCO ₃ , LiAlO ₂ , Al ₂ O ₃ , SiO , SnO, SnO ₂ , PbO ₂ , ZnO, P ₂ O ₅ , CuO, MoO, V ₂ O ₅ , B ₂ O ₃ , Si ₃ N ₄ , CeO ₂ , Mn ₃ O ₄ , Sn ₂ P ₂ O ₇ , Sn ₂ B ₂ O ₅ , Sn ₂ BPO ₆ One selected from the group consisting of combinations of two or more thereof, a separator coating composition. According to claim 1,
The content of the polymer binder in the separator coating composition is 1 to 10% by weight, the separator coating composition. According to claim 1,
The polymer binder is polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polyacrylic acid, polyacrylonitrile, polyvinylpyrrolidone , polyvinyl acetate, ethylene vinyl acetate, polyimide, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, Hydroxyethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, acrylonitrile-acrylic acid copolymer, ethylene-acrylic acid copolymer, styrene-butadiene copolymer, alkyl acrylate- One selected from the group consisting of acrylonitrile copolymer, polyethylene glycol, acrylic rubber, and a combination of two or more thereof, a separator coating composition. According to claim 1,
The content of the dispersant in the separator coating composition is 0.1 to 5% by weight, the separator coating composition. According to claim 1,
The dispersant is sodium metaphosphate, sodium hexametaphosphate, or a combination thereof, the membrane coating composition. delete According to claim 1,
The persulfate-based compound is metal persulfate, ammonium persulfate, or a combination thereof, the membrane coating composition. (a) processing a composition comprising a polyolefin and a pore former to prepare a porous support; and
(b) coating the separator coating composition according to any one of claims 1 to 8 and 10 on at least one surface of the porous support and drying at 50 to 100° C. for 0.5 to 10 minutes to form a coating layer A method of manufacturing a separation membrane comprising;