KR101806230B1 - Process for reforming polypropylene and electrode tab thereof - Google Patents

Abstract

The present invention relates to a process for producing a polypropylene solution, which comprises reacting a polypropylene solution with components such as (meth) acrylic acid, glycidyl methacrylate and epihalohydrin compounds under a peroxide catalyst, The present invention relates to a polypropylene reforming method and an electrode tab using the same, and has an excellent effect of bonding strength and electrolyte resistance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a process for reforming polypropylene,

The present invention relates to a method for modifying a polypropylene and an electrode tab using the same, and more particularly, to a method for modifying a polypropylene by imparting various functional groups to the polypropylene and an electrode tap using the modified polypropylene produced by the method will be.

2. Description of the Related Art [0002] Generally, a lithium secondary battery, which is a typical secondary battery, is composed of an electrode tab including an electrode portion including an anode and a cathode, a pouch encapsulating an electrolyte or the like, and a polymer film combining them. And may further include a metal foil or metal such as aluminum as an encapsulating material for encapsulating the lead wire for taking out the electricity of the positive electrode and the negative electrode to the outside.

The polymer film that combines such electrode parts and pouches is required to have properties such as moisture-proofing property, sealing property, insulation property, heat resistance, cold resistance and corrosion resistance, and particularly, a bonding force between each constitution and a bonding force between the polymer film itself is required. That is, the bonding force for each constitution is excellent and it should not be separated, and the bonding force of the polymer film itself is excellent, so that the film should not be peeled off. In addition, strong electrolyte resistance, which is not soluble in electrolytes, is also essential. For example, Korean patent KR1340242B1 discloses a method for producing a modified polyolefin resin which is suitable for blending with various kinds of polymers and can easily produce a high amount of modified polyolefin. However, And there is a problem that the electrolytic property is very poor. Korean Patent Publication No. KR2012-0102737A discloses a composition suitable for use as a crosslinked masterbatch comprising a functional polyolefin having improved bonding strength with a metal, but still has a problem of low electrolyte resistance, which is vulnerable to electrolytes.

Therefore, it is necessary to study the polymer resin or the polymer film which is excellent not only in the bonding force of the polyolefin itself and the bonding force with the metal, but also in the electrolyte resistance.

Korean registered patent KR1340242B1 Korean Patent Publication No. KR2012-0102737A

It is an object of the present invention to provide a polypropylene resin which is excellent in properties such as moisture-proof property, sealing property, insulation property, heat resistance property, cold resistance property and corrosion resistance property and is also excellent in bonding force of polypropylene itself, bonding force with non-polar substrate such as pouch, A method of modifying polypropylene so as to have excellent electrolytic properties and an electrode tab using the same.

Another object of the present invention is to provide a resin or film comprising a modified polypropylene for an electrode tab having improved mechanical properties such as tensile strength and tensile elastic modulus by a method of modifying polypropylene.

In order to solve the above problems, the present invention provides a polypropylene reforming method which is excellent in the bonding force of polypropylene itself, the bonding force with a non-polar substrate such as a pouch, the bonding force with a polar substrate such as metal, and the electrolyte resistance property, Tab.

In one aspect of the present invention, the electrode tab to which the modified polypropylene is applied may include an electrode portion including a metal, a pouch containing an electrolyte, and an adhesive layer for bonding the electrode portion and the pouch.

In one embodiment of the present invention, the adhesive layer includes a component containing at least one selected from glycidyl methacrylate and epihalohydrin compounds, and a modified polypropylene modified with a (meth) acrylic acid monomer .

In one embodiment of the present invention, the adhesive layer is not limited to attain the object of the present invention, but may be manufactured, for example, including a blend resin of a propylene polymer and the modified polypropylene.

In one example of the present invention, the propylene polymer is not limited to attain the object of the present invention, but any one selected from, for example, a propylene random polymer, a propylene homopolymer, a propylene copolymer, and a copolymer of propylene and another monomer, And may include two or more.

In another aspect of the present invention,

a) reacting a polypropylene solution with a component comprising at least one member selected from glycidyl methacrylate and epihalohydrin compounds and a (meth) acrylic acid monomer under a peroxide catalyst; and

b) removing the unreacted material

. ≪ / RTI >

In one embodiment of the present invention, the polypropylene solution in step a) is not limited to achieve the object of the present invention, but may be prepared, for example, by dissolving 10 to 2,000 parts by weight of a solvent in 100 parts by weight of a polypropylene resin.

In an example of the present invention, the step (a) is not particularly limited as long as the object of the present invention is achieved. However, it is preferable that the polypropylene resin composition contains 5 to 200 parts by weight of (meth) acrylic acid, And 0.1 to 100 parts by weight of a component containing at least one selected from an epihalohydrin-based compound and 0.01 to 10 parts by weight of a peroxide-based catalyst.

In one example of the present invention, the resin or film comprising the modified polypropylene produced by the above-mentioned polypropylene reforming method can be applied to an adhesive layer which bonds the pouch with the electrode portion constituting one of the electrode tabs.

The resin or film comprising a modified polypropylene having a functional group such as a carboxylic acid group or an epoxy group modified by the polypropylene reforming method of the present invention is excellent in properties such as moisture-proof property, sealability, insulation property, heat resistance, cold resistance and corrosion resistance , The bonding strength of the polypropylene itself, the bonding strength with the non-polar substrate such as the pouch, the bonding strength with the polar substrate such as metal, and the electrolyte resistance property.

The resin or film containing modified polypropylene by the polypropylene reforming method of the present invention has an advantage of excellent mechanical properties such as tensile strength and tensile elastic modulus.

In addition, the electrode tab of the present invention, in which the electrode portion and the pouch of the secondary battery are combined with the resin or the film containing the modified polypropylene, has the above-described characteristics as well as excellent durability.

Hereinafter, the polypropylene reforming method of the present invention and the electrode tab to which the present invention is applied will be described in detail.

Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the following description, the gist of the present invention is unnecessarily Descriptions of the blurred notice function and configuration are omitted.

Also, units of% used unclearly herein, unless otherwise specified, means weight.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the conventional art in which the bonding strength of the polymer film (the adhesive layer) for bonding the electrode part including the metal and the pouch and the like itself is deteriorated and peeled off, To solve the problems of separation and dissolution in the electrolyte and deterioration of electrolytic resistance. Therefore, the present invention relates to a polypropylene reforming method which is excellent in bonding force of polypropylene itself, bonding force with a non-polar substrate such as a pouch, bonding force with a polar substrate such as metal, and electrolyte resistance property.

In one embodiment of the present invention, the electrode tab to which the modified polypropylene manufactured by the modification method of the present invention is applied may include an electrode portion, a pouch, and an adhesive layer for bonding the electrode portion and the pouch.

In one embodiment of the present invention, the adhesive layer includes a component containing at least one selected from glycidyl methacrylate and epihalohydrin compounds, and a modified polypropylene modified with a (meth) acrylic acid monomer .

In the exemplary embodiment of the present invention, the electrode unit refers to a structure in which one or more electrodes (including metal) are coupled, and the number, shape, and structure of the electrodes may be appropriately adjusted So that it is not limited.

In one embodiment of the present invention, the pouch includes an electrolyte, and the electrolyte may be sealed to enclose the electrolyte. A secondary battery, and the like, and may be one generally used mainly for a lithium secondary battery or the like.

The electrode tab may further include an electrode lead (electrode lead wire). For example, the electrode tab may be provided on one side or one side to which the electrode portion and the pouch are coupled, To form a bonded structure comprising an adhesive layer sealingly bonded with propylene.

Therefore, when the electrode leads are additionally formed on the electrode tabs composed of the electrode parts, the pouches, and the adhesive layer for bonding the modified polypropylene, the bonding strength of the adhesive layer may be reduced as the structural stability is reduced. However, in the case of the adhesive layer to which the modified polypropylene of the present invention is applied, not only the bonding force of the polypropylene (or the polypropylene blend resin) itself, the bonding force with the non-polar substrate such as the pouch and the bonding force with the polar substrate such as metal are excellent, The electrolytic property also has an excellent effect.

In one embodiment of the present invention, the adhesive layer is not limited to attain the object of the present invention, but may be manufactured, for example, including a blend resin of a propylene polymer and the modified polypropylene.

In one example of the present invention, the propylene polymer is not limited to attain the object of the present invention, but any one selected from, for example, a propylene random polymer, a propylene homopolymer, a propylene copolymer, and a copolymer of propylene and another monomer, And may include two or more. In a preferred example, when the propylene polymer is a propylene random polymer and / or a propylene homopolymer, not only is it excellent in bonding force with a non-polar base material such as a pouch and with a polar base material such as a metal, Resin) itself (bonding force of the adhesive layer itself other than the bonding portion) is further improved, so that the phenomenon of breakage or breakage from the inside of the adhesive layer can be prevented.

In one embodiment of the present invention, the blend resin is not limited to attain the object of the present invention. For example, 0.1 to 100 parts by weight, preferably 0.1 to 50 parts by weight, of the modified polypropylene per 100 parts by weight of the propylene polymer , And more preferably 0.2 to 30 parts by weight. When the above range is satisfied, it is possible to further prevent the phenomenon of breakage or tearing from the inside of the adhesive layer.

Hereinafter, the method of modifying the modified polypropylene of the adhesive layer applied to the electrode tab of the present invention will be described in detail.

In another embodiment of the present invention, the modified polypropylene-

a) reacting a polypropylene solution with a component comprising at least one member selected from glycidyl methacrylate and epihalohydrin compounds and a (meth) acrylic acid monomer under a peroxide catalyst; and

b) removing the unreacted material

. ≪ / RTI >

In one embodiment of the present invention, the step a) may include a step of dissolving a solvent in the polypropylene resin to prepare a polypropylene solution. As a specific example, the step a) may be a step of heating and dissolving a solvent in a polypropylene resin under a nitrogen atmosphere to prepare a polypropylene solution.

In one embodiment of the present invention, the polypropylene solution in step a) is not limited to achieve the object of the present invention, but may be prepared, for example, by dissolving 10 to 2,000 parts by weight of a solvent in 100 parts by weight of a polypropylene resin.

In one example of the present invention, the polypropylene resin is not limited to attain the object of the present invention, but includes any one or two or more selected from a propylene homopolymer, a propylene copolymer, and a copolymer of propylene and another monomer can do. Specific examples of the polypropylene resin include high density polypropylene (HDPP), low density polypropylene (LDPP), linear low density polypropylene, isotactic polypropylene, and atactic polypropylene. When such a polypropylene resin is used, the probability of imparting functional groups such as a carboxylic acid group and an epoxy group can be improved, which is preferable. However, this is a preferable example, but the present invention is not limited thereto.

In one embodiment of the present invention, the solvent of step (a) is not limited as long as the object of the present invention is achieved. Examples of the solvent include hydrocarbon solvents such as toluene, xylene, and cyclic nucleic acid, methyl ethyl ketone, methyl isobutyl ketone Ester solvents such as ethyl acetate, butyl acetate and the like; ether solvents such as dioxane and ethylene glycol diethyl ether; and aliphatic hydrocarbons such as pentane, hexane and heptane. Or < / RTI > Although the use of toluene in the above listed solvents is preferred in terms of viscosity control, this is a preferred example, but the present invention is not limited thereto.

In one embodiment of the present invention, the step (a) is a step in which a component containing at least one selected from the group consisting of glycidyl methacrylate and epihalohydrin compounds and a component containing a (meth) acrylic acid monomer in a polypropylene solution are mixed with a peroxide Based catalyst and reacting it. Specifically, it is possible to prepare a polypropylene solution, (meth) acrylic acid and a modified polypropylene having a carboxylic acid group and an epoxy group in the course of reacting the components under a peroxide-based catalyst. Therefore, the bonding force of the polypropylene itself, the bonding force with the non-polar substrate, the bonding force with the polar substrate such as metal, and the electrolyte resistance can be improved.

In one embodiment of the present invention, the reaction temperature in the step a) is not limited as long as the object of the present invention is achieved. For example, it may be 70 to 150 ° C, preferably 80 to 130 ° C. The reaction at a temperature of 70 ° C or higher can improve the reaction of the carboxyl group and the epoxy group in the polypropylene, but this is a preferred example, but the present invention is not limited thereto.

In an example of the present invention, the step (a) is not particularly limited as long as the object of the present invention is achieved. However, it is preferable that the polypropylene resin composition contains 5 to 200 parts by weight of (meth) acrylic acid, And 0.1 to 100 parts by weight of a component containing at least one selected from an epihalohydrin-based compound and 0.01 to 10 parts by weight of a peroxide-based catalyst. The reaction within the above range is preferably carried out by appropriately applying a carboxylic acid group and an epoxy group to the polypropylene to improve the bonding force of the polypropylene itself, the bonding force with the non-polar substrate such as the pouch, the bonding force with the polar substrate such as metal, . However, this is a preferable example, but the present invention is not limited thereto.

In the present invention, (meth) acrylic acid is used in order to modify the modified polypropylene having more excellent physical properties, but it is also possible to use maleic acid, itaconic acid, citraconic acid, hyaluronic acid, bicyclo , 2) octa-5-ene-2,3-dicarboxylic acid, 4-methylcyclohexa-4-ene-1,2-dicarboxylic acid, 1,2,3,4,5,8,9,10-octahydro Naphthalene-2,3-dicarboxylic acid, bicyclo (2,2,1) octa-7-ene-2,3,5,6-tetracarboxylic acid, 7-oxabicyclo (2,2,1) -En-2,3-dicarboxylic acid and the like can also be used.

In one embodiment of the present invention, in the step a), a component including at least one selected from glycidyl methacrylate and epihalohydrin-based compounds may be used to impart an epoxy group to the polypropylene.

In one example of the present invention, glycidyl methacrylate is mentioned in order to modify the modified polypropylene having more excellent physical properties, but derivatives of glycidyl methacrylate and the like can be used in addition to the above.

In one embodiment of the present invention, the epihalohydrin compound is not limited to attain the object of the present invention, but may be any compound selected from epichlorohydrin, epibromohydrin, and? -Methyl epichlorohydrin, One or two or more. Among the epihalohydrin compounds listed above, the use of epichlorohydrin is advantageous in that it is easy to use from a general viewpoint and has an excellent epoxy group-imparting ability, but this is a preferred example, but the present invention is not limited thereto.

In one embodiment of the present invention, the peroxide-based catalyst is not limited as far as the object of the present invention is achieved. Any one selected from dicumylperoxide, methylethylketoneperoxide, benzoylperoxide and dibenzoylperoxide, And may include two or more. Among the peroxide-based catalysts listed above, the use of dicumyl peroxide may improve the degree of bonding of the carboxylic acid group and the epoxy group on the basis of the unit average molecular weight, but this is merely a preferred example, but the present invention is not limited thereto.

In one embodiment of the present invention, the step of removing the unreacted material in the step b) may include a step of removing the remaining unreacted material using a cleaning solvent. Specifically, the modified polypropylene obtained in the step a) is washed several times with a washing solvent such as acetone to obtain a solution of (meth) acrylic acid, glycidyl methacrylate, epihalohydrin compound and peroxide-based catalyst And removing the reactants. Further, the cleaning solvent is not limited as long as it does not react with the modified polypropylene, so that a known cleaning solvent may be used.

In one embodiment of the present invention, the step of removing the unreacted material in step b) may include a step of filtering.

In one embodiment of the present invention, the step b) may include a drying step. Specifically, it may include washing and / or filtration, followed by drying with a reduced pressure dryer or the like to distill off the remaining unreacted material. As a specific but non-limiting example, the step of washing and / or filtering the modified polypropylene obtained in the step a) may be followed by a step of distilling off unreacted materials such as epihalohydrin compounds in a vacuum dryer .

In one example of the present invention, the drying temperature using the reduced-pressure dryer or the like is not particularly limited so long as the object of the present invention is achieved. For example, the drying temperature is 50 to 180 ° C, preferably 60 to 160 ° C, more preferably 70 to 150 ° C Lt; / RTI > However, this is a preferable example, but the present invention is not limited thereto.

In one example of the present invention, the drying time using the reduced-pressure dryer or the like is not limited so long as the object of the present invention is achieved, but may be, for example, 0.5 to 3 hours. However, this is a preferable example, but the present invention is not limited thereto.

As described above, the modified polypropylene in which the unreacted material has been removed by the multistage elimination method in the step b) is subjected to kneading / extruding, and then the modified polypropylene resin or the blended resin containing the electrode part and the electrolyte Can be used as a polymer film that combines pouches filled with a polymer.

In another aspect of the present invention, a method for producing a modified polypropylene resin for an electrode tap film using the modified polypropylene of the present invention may include a step of mixing and kneading the modified polypropylene and the polymer, and a step of extruding.

In the example of the present invention, the step of kneading is not limited as long as the object of the present invention is achieved. However, the step of blending the modified polypropylene and the high molecular weight polymer (such as the propylene polymer) with a blender such as a tumbler blender . ≪ / RTI > As a specific example, the modified polypropylene and the propylene polymer may be mixed with a blender such as a tumbler blender and kneaded for 1 to 30 minutes to prepare a blend resin.

In one embodiment of the present invention, the step of extruding is not limited as far as the object of the present invention is achieved. For example, the extruder may be extruded at a temperature of 200 to 250 캜, preferably 220 to 230 캜, using an extruder such as a twin- It is preferable to proceed at a screw speed of 200 to 400 rpm, preferably 250 to 350 rpm, and it is preferable to pass the resin through 200 to 600 mesh, preferably 300 to 500 mesh filter. In the case of kneading and extruding in this manner, the binding strength of the modified polypropylene and the propylene polymer is improved, and finally a modified polypropylene resin for an electrode tap film having a uniform distribution degree can be produced.

As described above, the resin or film containing the modified polypropylene produced by the polypropylene reforming method can be used for bonding the pouch with the electrode portion including the metal which is the constitution of the electrode tab. Therefore, the electrode tab made of the adhesive layer including the electrode portion, the pouch and the modified polypropylene for bonding the electrode portion, the pouch and the pouch is excellent not only in the properties such as moisture resistance, heat resistance, cold resistance and corrosion resistance, but also the bonding strength of the polypropylene itself A bonding strength with a non-polar base material, a bonding force with a polar base material such as a metal, and an electrolyte resistance property, and thus has an excellent durability.

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

1 kg of a propylene copolymer (VESTOPLAST 408, Evonix) was added to 9 kg of toluene and dissolved by heating in a nitrogen atmosphere, and then 0.4 kg of methacrylic acid monomer, 0.1 kg of epichlorohydrin and 0.01 kg of dicumyl peroxide And a modified polypropylene resin having a carboxylic acid group and an epoxy group was prepared. The modified polypropylene resin was washed three times with acetone to remove unreacted materials. Subsequently, the pressure was sufficiently reduced at 100 DEG C for 1 hour or longer by a reduced pressure dryer to remove the solvent such as acetone. The modified polypropylene resin thus prepared was measured by a Fourier transform infrared spectrophotometer (FT-IR), and it was confirmed that the peak of the carboxylic acid group and the peak of the epoxy group were confirmed.

1 kg of the modified polypropylene resin and 9 kg of propylene homopolymer (VESTOPLAST 792, Evonix) were blended with a tumbling blender and kneaded for 10 minutes, and then kneaded using a 58 mm twin extruder at a screw speed of 280 rpm at 225 DEG C mesh filter to prepare a blend resin for electrode taps in which pellet-shaped modified polypropylene resin was uniformly mixed.

A blend resin for electrode taps was prepared in the same manner as in Example 1, except that 0.5 kg of the modified polypropylene resin of Example 1 and 9.5 kg of propylene homopolymer (VESTOPLAST 792, Evonix) were blended with a tumbling blender.

A blend resin for electrode taps was prepared in the same manner as in Example 1 except that 9 kg of a modified polypropylene resin of Example 1, 1 kg of propylene copolymer (VESTOPLAST) 888, Evonix) was blended with a tumbling blender.

A blend resin for electrode taps was prepared in the same manner as in Example 1, except that 0.5 kg of the modified polypropylene resin of Example 1 and 9.5 kg of a propylene copolymer (VESTOPLAST) 888, Evonixa were blended with a tumbling blender.

A blend resin for electrode taps was prepared in the same manner as in Example 1, except that 1 kg of the modified polypropylene resin of Example 1 and 9 kg of a propylene random polymer (RANPELEN SFC-851, Lotte Chemical Co., Ltd.) were blended with a tumbling blender.

A blend resin for electrode taps was prepared in the same manner as in Example 1, except that 0.5 kg of the modified polypropylene resin of Example 1 and 9.5 kg of a propylene random polymer (RANPELEN SFC-851, Lotte Chemical) were blended with a tumbling blender.

A blend resin for electrode taps was prepared in the same manner as in Example 1, except that glycidyl methacrylate was used instead of epichlorohydrin of Example 1.

Table 1 below shows the tensile strength and tensile elastic modulus of the polymeric resin for electrode taps according to Examples 1 to 6 according to the ASTM D 638: 2010 method and the thermal bonding strength of the polymeric resin according to ASTM F88-09 And the results are shown in Fig.

In Examples 1 to 6, both of the tensile strength, the tensile elastic modulus and the heat bonding strength were excellent, and it was confirmed directly or indirectly that the bonding strength of the polypropylene itself, the bonding force with the non-polar substrate such as the pouch, .

It was also confirmed that Examples 5 and 6, which were blended with propylene random polymer, were more excellent in both tensile strength, tensile elastic modulus and heat resistance than Examples 1 to 4 which were not blended.

In addition, in Example 7 using glycidyl methacrylate, the tensile strength and the tensile elastic modulus were superior to those of Example 1 using epichlorohydrin, and the heat bonding strength was also remarkably excellent.

Also, the airtightness test was performed on the electrode tabs sealed between the metal of the electrode part and the pouch with the blend resin prepared in Example 1 and the modified polypropylene resin prepared in Example 1, respectively. As a result, it was confirmed that the airtightness (sealability) was maintained even at 8 atm in the case of the electrode tab to which the modified polypropylene resin was applied, and the electrolyte inside the pouch did not leak even in the case of the electrode tab to which the blended resin was applied, .

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents.

Claims (9)

A metal electrode portion;
pouch; And
And an adhesive layer for directly bonding the metal electrode portion and the pouch,
Wherein the adhesive layer comprises a propylene homopolymer and a blend resin comprising 0.2 to 30 parts by weight of a modified polypropylene with respect to 100 parts by weight of the propylene homopolymer,
Wherein the modified polypropylene is modified with an epichlorohydrin compound and a (meth) acrylic acid monomer. delete delete delete A method of manufacturing a resin for sealing an electrode tab in which a metal electrode portion and a pouch are directly bonded,
Adding a epichlorohydrin compound and a (meth) acrylic acid monomer to a polypropylene solution under a peroxide catalyst to produce a modified polypropylene; and
And kneading the modified polypropylene and the propylene homopolymer to prepare a blend resin,
Wherein the blend resin comprises 0.2 to 30 parts by weight of the modified polypropylene with respect to 100 parts by weight of the propylene homopolymer. 6. The method of claim 5,
Wherein the polypropylene solution is prepared by dissolving 10 to 2,000 parts by weight of a solvent in 100 parts by weight of a polypropylene resin. The method according to claim 6,
Wherein the modified polypropylene comprises 5 to 200 parts by weight of (meth) acrylic acid, 0.1 to 100 parts by weight of an epichlorohydrin compound, and 0.01 to 10 parts by weight of a peroxide-based catalyst, based on 100 parts by weight of the polypropylene resin. A method for producing an encapsulating resin. 6. The method of claim 5,
Wherein the epichlorohydrin-based compound contains at least one selected from epichlorohydrin and? -Methyl epichlorohydrin. delete