KR101978518B1 - Multilayer aramid paper separator and manufacturing method thereof - Google Patents

Abstract

The production method of the present invention is capable of producing an aramid multilayer paper separation membrane by a single manufacturing process, and thus is excellent in workability and economy. Further, a pair of rectifying rolls rotating in mutually opposite directions are provided to essentially block the accumulation of the stock, thereby ensuring a homogeneous quality.
Furthermore, the thickness of the aramid paper separator can be minimized to maximize the battery packaging efficiency. In particular, the ion exchange capability and the shut-down capability are enhanced and the interlayer adhesion force is enhanced to minimize the delamination phenomenon, which is suitable for high capacity and high efficiency cells .

Description

TECHNICAL FIELD The present invention relates to an aramid multilayer paper separator,

More particularly, the present invention relates to an aramid multi-layered paper separation membrane and a method of manufacturing the same. More particularly, the present invention provides an aramid multi-layered paper separation membrane capable of remarkably improving interlaminar bond strength, The present invention relates to an aramid multi-layered paper separator which is excellent in charging efficiency while being capable of being used as a separator.

With the rapid development of the electronics, communications and computer industries, portable electronic communication devices such as camcorders, mobile phones and notebook PCs are making remarkable progress. Accordingly, the demand for lithium secondary batteries as power sources capable of driving them has been increasing day by day. In recent years, research and development have been actively carried out not only in domestic but also in Japan, Europe and the United States, with regard to applications such as electric vehicles, uninterruptible power supply devices, power tools and satellites as well as power sources for portable electronic devices as well as eco- .

Generally, the structure of a lithium secondary battery is composed of a positive electrode containing a lithium-transition metal composite oxide, a negative electrode capable of intercalating and deintercalating lithium ions, a separator interposed between the positive and negative electrodes, and an electrolyte for facilitating lithium ion migration .

In general, the function of the separator is not only to isolate the anode and the cathode, but also to maintain the electrolyte and provide high ion permeability. In addition, a separation membrane having a shutdown function that a part of the separation membrane is melted to block the pore to block the current when a large amount of current flows due to a partial short-circuit has recently been proposed. In addition, a technique of preventing contact between the electrode plates by increasing the area of the electrodes of the positive electrode and the negative electrode has been proposed. However, in this case, a function of preventing short- . Particularly, lithium secondary batteries, which require large-sized batteries and high energy density, are continuously maintained at a high charging / discharging state due to recent trends, so that the temperature in the battery rises. Therefore, heat resistance and thermal stability Is also required.

Conventionally, a porous membrane made of a sheet made of a polyolefin-based polymer such as polyethylene (PE) or polypropylene (PP) has been widely used. The separator made of polyethylene having a melting temperature of 130 ° C or polypropylene having a melting temperature of 170 ° C is heat-shrunk / melted due to a heat generated when an excessive current flows in the battery due to a short circuit or an external factor, In conjunction with this, the micropores are closed, thereby blocking current flow (shutdown).

However, in addition to the shutdown characteristic, the shape retention of the separator when the temperature rises continuously after shutdown becomes an important factor. If the temperature rise is continued due to internal or external factors even after shutdown when used in a melting temperature range such as polyethylene or polypropylene, the separation membrane itself is melted and the separation membrane shape is lost and the electrode is short-circuited and becomes a dangerous state.

Therefore, in order to improve the strength and physical properties of the separator, an aramid separator having an aramid layer adhered to both sides of the polyolefin layer with an adhesive and / or an adhesive has been proposed. However, due to the presence of the adhesive layer, There is a problem that ion exchange performance is deteriorated. Accordingly, a separation membrane for casting an aramid layer on both sides of the polyolefin layer has been proposed.

On the other hand, the aramid type film type separator is mainly used as a separator of a small capacity battery, and in case of a large capacity, an aramid type separator is used. More specifically, FIG. 1 illustrates a twin-screw paper machine for manufacturing a conventional aramid paper separator. Referring to FIG. 1, the head box 10 is filled with a stock material. The material to be extruded from the head box 10 is supported by the inner supporting wire net 20 and the outer feeding wire net 30 while passing through the two rollers 21 and 31 and the vacuum dewatering device through nozzles at the end, Is formed along the outer conveying wire net (30) formed in the shape of a circle (1), paper fills are formed, and is discharged to the outside. Since the formed material is a single wetland, wetlands of different materials are produced by laminating the same to produce a separation membrane satisfying the above-mentioned properties. That is, a single layer of aramid wet paper is manufactured using the apparatus of FIG. 1, and another layer of aramid wet paper and polyolefin wet paper are separately prepared, and then the three wet paper are wet-matched and then calendered To produce a membrane.

However, since individual wetlands must meet a minimum required basis weight, a thickness somewhat greater than that required is indispensable. As a result, when three wet paper sheets are prepared and wetted, the thickness of the aramid paper separation membrane becomes excessively thick, resulting in a problem that the packaging efficiency of the battery significantly decreases.

Furthermore, if three wet paper webs are prepared and wetted, wet paper webs are peeled off easily due to weak interlayer bonding force even after calendering.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to minimize the thickness of the aramid paper separating membrane to maximize the cell mounting efficiency and simultaneously enhance the ion exchange capacity and shut- To provide an aramid multilayer paper separation membrane capable of minimizing delamination by enhancing the interlayer bonding force and a method of manufacturing the same.

The method for producing an aramid multilayer paper separation membrane of the present invention for solving the above problems is characterized in that (1) a paper manufacturing apparatus comprising one head box having two or more partitioned feed ports is provided with at least one of polyolefin and polyester (1), wherein the component (1) comprises a first feedstock comprising one or more composite fibers and at least one second feedstock comprising an aramid component; (2) the first and second materials charged through the head box communicate with the respective material input ports and are transported through the divided channels; (3) two or more feeds discharged from the two or more flow paths are combined and discharged from one nozzle to form a multi-layer wet paper; and (4) compressing the multi-layer wet paper.

According to a preferred embodiment of the present invention, the head box may have three or more feed-in ports. In this case, one of the three or more feed-in ports may be inserted into the middle- 2 We can input the material.

According to another preferred embodiment of the present invention, the second support material may comprise any one or more polymers selected from the group consisting of meta-aramid, para-aramid and meta-para-aramid.

According to another preferred embodiment of the present invention, the meta-aramid is at least one selected from the group consisting of poly (metaphenylene isophthalamide), poly (m-benzamide), poly (m-phenylene isophthalamide) m'-phenylene benzamide), and poly (1,6-naphthylene isophthalamide), and the para-aramid may be at least one selected from the group consisting of poly (paraphenylene terephthalamide), poly (p-phenylene p, p'-biphenyldicarboxamide), poly (p-phenylene 1,5-naphthylene dicarboxamide), poly (trans, trans-4,4'-dodecahydro Biphenylene terephthalamide), poly (trans-1,4-cinnamamide), poly (p-phenylene 4,8-quinolinedicarboxamide), poly (1,4- [ (P-phenylene 4,4'-azoxybenzene dicarboxamide / terephthalamide), poly (p-phenylene-4,4'-trans-stilbenecarbox Meade) and poly (p- Alkenylene dicarboxylic acetylene may be at least one selected from the group consisting of carboxamide), the meta-para-aramid may be poly (meta-phenylene terephthalamide).

According to another preferred embodiment of the present invention, the polyolefin is at least one selected from the group consisting of polyethylene and polypropylene, polybutene and polymethylpentene, and the polyester is at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate Phthalate, and polyethylene naphthalate.

According to another preferred embodiment of the present invention, the second material may include 60 to 200 parts by weight of aramid flock with respect to 100 parts by weight of the aramid fibrids.

According to another preferred embodiment of the present invention, the first finishing material may include 20 to 70 parts by weight of fibrids with respect to 100 parts by weight of the composite fibers.

According to another preferred embodiment of the present invention, the nozzle may become narrower toward the discharge end.

According to another preferred embodiment of the present invention, at least one of the flow paths may include a pair of rectifying rolls rotated in opposite directions to each other.

According to another preferred embodiment of the present invention, the step (4) may be an alkali loss or a water loss.

According to another preferred embodiment of the present invention, the length of the chart and slice is 1 to 10 mm.

According to another preferred embodiment of the present invention, the microfine yarns may have a fineness of 0.01 to 0.2 denier.

According to another preferred embodiment of the present invention, there is provided a polyolefin composition comprising at least one component (1) of a polyolefin and a polyester, wherein the component (1) comprises a porous first layer comprising at least one of a polyolefin and a polyester, And a porous second layer comprising an aramid formed on at least one side of the first layer; And a porous first mixed layer in which a first layer component and a second layer component are mixed between the first layer and the second layer.

According to another preferred embodiment of the present invention, the second layer may comprise at least one polymer selected from the group consisting of meta-aramid, para-aramid and meta-paraaramide.

According to another preferred embodiment of the present invention, the meta-aramid is at least one selected from the group consisting of poly (metaphenylene isophthalamide), poly (m-benzamide), poly (m-phenylene isophthalamide) m'-phenylene benzamide), and poly (1,6-naphthylene isophthalamide); The para-aramid may be selected from the group consisting of poly (paraphenylene terephthalamide), poly (p-phenylene p, p'-biphenyldicarboxamide), poly (p- , Poly (trans-trans-4,4'-dodecahydrobiphenylene terephthalamide), poly (trans-1,4-cinnamamide), poly (p-phenylene 4,8-quinolinedicarboxamide) , Poly (1,4- [2,2,2] -bicyclooctyleneterephthalamide), copoly (p-phenylene 4,4'-azoxybenzene dicarboxamide / terephthalamide), poly (p -Phenylene-4,4'-trans-stilbene carboxamide) and poly (p-phenylene acetylene dicarboxamide); The meta-para aramid may be poly (metaphenylene terephthalamide).

According to another preferred embodiment of the present invention, the polyolefin is at least one selected from the group consisting of polyethylene and polypropylene, polybutene and polymethylpentene, and the polyester is at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate Phthalate, and polyethylene naphthalate.

According to another preferred embodiment of the present invention, the microfine yarns may have a fineness of 0.01 to 0.2 denier.

According to another preferred embodiment of the present invention, the second material may include 60 to 200 parts by weight of aramid flock with respect to 100 parts by weight of the aramid fibrids.

According to another preferred embodiment of the present invention, the first stock material may include 20 to 70 parts by weight of fibrids with respect to 100 parts by weight of the sea-island composite fibers.

According to another preferred embodiment of the present invention, the thickness of the first layer is 3 to 8 탆, the thickness of the first mixed layer is 0.5 to 5 탆, and the thickness of the second layer is 3 to 8 탆 .

According to another preferred embodiment of the present invention, the second layer includes a porous third layer including aramid on the other side of the first layer; And a porous second mixed layer in which a first layer component and a third layer component are mixed between the first layer and the third layer.

According to another preferred embodiment of the present invention, the thickness of the aramid multilayer paper separation membrane is 12 to 20 μm, the tensile strength is 2200 gf / 15 mm or more, the air permeability is 50 to 300 sec / 100 ml and the resistance value is 0.5 to 1.5 Ω .

Hereinafter, terms used in the present invention will be defined.

&Quot; Flock " refers to fibers of shorter length than staple fibers. The length of the flocs is from about 0.5 to about 15 mm and the diameter is from 4 to 50 micrometers, preferably from 1 to 12 mm in length and from 8 to 40 micrometers in diameter. Aramid floc can be produced by cutting aramid fibers to short lengths without significant or optional fibrillization, such as those produced by the methods described in U.S. Patent Nos. 3,063,966, 3,133,138, 3,767,756 and 3,869,430 .

The term "fibrids" refers to non-granular pulp or film-like particles. Preferably, the melting point or decomposition point thereof may exceed 320 ° C. The fibrids have an average length of 0.5 to 2 mm and an aspect ratio of 15: 1 to 50: 1. Including the use of a fibridation apparatus of the type disclosed in U.S. Patent No. 3,018,091, and any method in which the polymer solution is precipitated and sheared in a single step.

The production method of the present invention is capable of producing an aramid multilayer paper separation membrane by a single manufacturing process, and thus is excellent in workability and economy. Further, a pair of rectifying rolls rotating in mutually opposite directions are provided to essentially block the accumulation of the stock, thereby ensuring a homogeneous quality.

Furthermore, the thickness of the aramid paper separator can be minimized to maximize the battery packaging efficiency. In particular, the ion exchange capability and the shut-down capability are enhanced and the interlayer adhesion force is enhanced to minimize the delamination phenomenon, which is suitable for high capacity and high efficiency cells .

1 is a schematic view of an apparatus for producing an aramid multilayer paper separation membrane according to the prior art.
2 is a schematic view of an apparatus for producing an aramid multilayer paper separation membrane according to an embodiment of the present invention.
3 is an enlarged view of a portion A shown in Fig.
4 is a perspective view of a rectifying roll installed in the manufacturing apparatus according to the present invention.
5 is a schematic view showing a flow of fluid in a flow path portion provided with a rectifying roll in a manufacturing apparatus according to the present invention through a wire.
6 is a cross-sectional view of an aramid multilayer paper separation membrane according to a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings.

As described above, the conventional aramid paper type separation membrane is manufactured by preparing an individual wet paper, calibrating the same, and then calendering. In this case, since the individual wet paper must satisfy the minimum required basis weight, Is required. As a result, when three wet paper sheets are prepared and wetted, the thickness of the aramid paper separation membrane becomes excessively thick, resulting in a problem that the packaging efficiency of the battery significantly decreases.

Accordingly, the method for producing an aramid multilayer paper separation membrane of the present invention comprises the steps of (1) a paper manufacturing apparatus comprising one head box having two or more partitioned feed openings, and at least one component (1) of polyolefin and polyester, The component (1) comprises a first feedstock comprising at least one of composite chart fibers and split fibers, and a second feedstock comprising an aramid component; (2) the first and second materials charged through the head box communicate with the respective material input ports and are transported through the divided channels; (3) two or more feeds discharged from the two or more flow paths are combined and discharged from one nozzle to form a multi-layer wet paper, and (4) the multi-layer wet paper is reduced to form micro- And solved the above-mentioned problem. As a result, the aramid multilayer paper separating membrane can be produced by a single manufacturing process, and therefore, workability and economy are excellent. Further, since the interlaminar bond strength of the aramid multi-layer paper separation membrane manufactured by the manufacturing method of the present invention can be remarkably improved to reduce the thickness of the separation membrane, the packaging efficiency of the battery can be remarkably improved. In addition, the porosity is improved, the ion exchange capacity is maximized, the shut-down function can be sufficiently exhibited, and the charging efficiency is high, so that the battery can be applied to a high-capacity high-efficiency battery.

First, a preferable paper making apparatus that can be used in the present invention will be described with reference to FIG. 2, the manufacturing apparatus according to the present invention includes a head box 100 having feed channels 111, 112, and 113 formed therein so as to extrude landfills and narrowed ends of the channels 111, 112, and 113 to form a nozzle N, And a plurality of rollers 121 and 131 for circulating the wire net 120 and 130. Here, the head box 100 is divided into a plurality of flow paths 111, 112, and 113 so that the material to be extruded is formed into a multi-layered wet paper, and the aramid wet paper is discharged through at least one of the flow paths, There are provided rectifying rolls 400 and 500 which are rotated in mutually opposite directions on the intermediate flow path to be formed. That is, a major feature of the present invention resides in the head box 100 for manufacturing the multilayered separator paper 300. Therefore, the driving parts for the wire net 120 and 130 shown in FIG. 1 are omitted.

The head box 100 is formed with containers 101, 102 and 103 having three respective filtration sections 101a, 102a and 103a. Each of the three feeds from the three containers 101, 102 and 103 passes through three flow passages 111, 112 and 113 And is extruded to the nozzle (N) at the end. The flow path case 200 constituting the three flow paths 111, 112 and 113 has a long outer panel, and barrier ribs 210 and 220 are formed in the outer panel to partition the three flow paths. The distance between the flow path case 200 and the barrier ribs 210 and 220 is reduced at a certain angle with respect to each other, and is set to end at the nozzle N shown in FIG. Therefore, the respective materials in the respective containers 101, 102 and 103 pass through different flow paths 111, 112 and 113 and are extruded into the nozzles N. [ Each of the extruded stocks is joined at the end of the nozzle N and enters between the wire nets 120 and 130 to be transported by the rotational force of the rollers 121 and 131 together with the wire nets 120 and 130 to produce a multi-layer wet paper. In particular, a pair of rectifying rolls 400 and 500 which rotate in opposite directions are provided in the intermediate flow path 112. Since the flow path 112 is narrowed toward the nozzle side, the diameter of the roll 400 near the nozzle N is small Respectively.

3, the portion of the nozzle N is enlarged. The flow path case 200 is divided into three flow paths 111, 112 and 113 by two partition walls 210 and 220 and a gap distance between the ends of the nozzles N of the three flow paths 111, 112 and 113 is set to La, Lb and Lc And is configured to be changeable thereafter. By adjusting the clearances La, Lb and Lc, the characteristics and thickness of the discharged (extruded) product can be adjusted.

Here, when the first stock material (polyolefin or the like) is supplied to the intermediate container 102 and the second stock material (aramid) is supplied to the upper and lower containers 101 and 103 to be extruded, As the material is extruded, a multi-layered wetland is formed. Here, since the first stock material supplied to the intermediate container 121 is provided with the rectifying rolls 400 and 500 and is prevented from being bundled, the homogeneous quality is obtained when the nozzle N exits.

The multi-layered wet paper discharged through the nozzles N is extruded between the two rollers 121 and 131 as shown in FIG. 2, and guided by the wire nets 120 and 130 to be transported and transported and dried. That is, the manufacturing process of the multi-layered separator paper 300 is completed by using one piece of equipment by differentiating the structure of the head box 100.

According to several experiments, the gap distance (La, Lb, Lc) of the nozzle was adjusted to produce various quality separator paper. According to the results, it was found that the ratio of the clearances La, Lb and Lc should be controlled within the range of 4: 2: 4 to 3: 4: 3.

In addition, the thickness and characteristics of the mixed layer can be changed by controlling the pressures of the containers 101, 102, That is, by increasing or decreasing the speed of the intermediate flow path 112, it is possible to improve the intermediate bonding force by adjusting the mixed layer. Also, the mixing ratio of the materials of the respective layers can be adjusted by adjusting the speed ratio of the wire nettings 120 and 130.

Referring to FIG. 4, the shape of the rectifying rolls 400 and 500 can be seen. A plurality of holes 400a are uniformly formed in the shape of a long pipe of the rectifying rolls 400 and 500. [ The material enters and leaves through the holes 400a. In addition, since it is rotated at a constant speed of the rectifying rolls (400, 500), the accumulation of the stocks is prevented, and if the rotation speed is controlled well, uniform flow is maintained. That is, referring to FIG. 5, by providing a pair of rectifying rolls 400 and 500 that rotate in opposite directions, the accumulation of the stock is prevented and the turbulence is reduced through the holes 400a of the rectifying rolls 400 and 500 The profile of the stock velocity flowing along the passages 111, 112 and 113 becomes uniform. When the flow is adjusted in this way, long fibers are accumulated at the edge of the nozzle (N) to prevent defects of the paper from being generated. Further, in order to prevent uneven flow of vortex generated between the roll 400 and the roll 400, the rectifying rolls 400 and 500 are rotated in opposite directions to each other while maintaining the rotation speed in the range of 25 to 60% do.

Next, a method for manufacturing an aramid multi-layered paper separation membrane of the present invention will be described with reference to the above-described paper making apparatus of the present invention.

First, in step (1), a paper manufacturing apparatus including one head box having two or more divided paper input ports includes at least one component (1) of a polyolefin and a polyester, wherein the component (1) And a second stock material containing an aramid component are put into each of the first fiber bundle and the second fiber bundle. In the present invention, a plurality of wetlands are produced, and then the wet paper such as aramid wet paper, polyolefin, Thus, a paper making apparatus that can be used in the present invention includes one head box having two or more compartmented filling inlets.

The first and second stocks are loaded into the containers 101, 102, and 103, respectively, including the respective divided stock input ports 101b, 102b, and 103b. The charged first and second stocks can be introduced into the respective charge input ports through a fan pump (not shown). In the following description, the first and second materials are charged into the central charging port 102b, and the second charging materials are respectively disposed in the upper and lower portions of the first charging material 101b , 103b will be mainly described.

Preferably, the materials that can be used in the first feedstock of the present invention can be used without limitation as long as they can be used in polymeric porous membranes conventionally used in separation membranes. Preferably, the first feedstock is a polyolefin and a polyester And the like. The polyolefin preferably includes at least one selected from the group consisting of polyethylene and polypropylene, polybutene and polymethylpentene, and the polyester may be at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate Etoro. ≪ / RTI >

In this case, the first feedstock may comprise fibrids and / or flocs comprising one or more materials selected from the group consisting of polyolefins and polyesters.

Further, the first stock material of the present invention includes one or more composite fibers of a sea chart yarn and a split yarn comprising at least one of polyolefin and polyester. The chart and / or sliced yarn is then left in the form of microfine yarn in the final separation membrane through a reduction step, thereby remarkably improving the porosity and ion exchange ability of the separation membrane and remarkably improving the charging efficiency, thereby being suitable for a large capacity high efficiency battery I will.

Preferably, when the composite fiber is a chart paper, the microparticles contain at least one component selected from the group consisting of polyolefins and polyesters as a separation membrane component, and the marine components are then subjected to an alkali-soluble polymer and / Or a water-soluble polymer. The alkali-soluble polymer which can be used at this time is not particularly limited as long as it is usually used for producing microfibers and can be eluted into an alkali solution, and is preferably a commonly used polyester-based usable polymer or polyester A water-soluble polymer may be used. The total fineness of sea water can be from 1 to 10 denier, the single filament fineness can be from 0.01 to 0.2 denier, and the number of island components can be from 9 to 700.

In the case of the split yarn, it is also the same as the sea chart in which the alkali-soluble polymer and / or the water-soluble polymer is used so as to enable reduction in the amount of alkali or water loss. In this case, the total fineness of the preferred split yarns may be 1 to 10 denier, the single yarn fineness may be 0.2 to 0.8 denier, and the number of the component components may be 4 to 40.

The length of the composite fiber may be 1 to 10 mm. If the length of the conjugate fiber is less than 1 mm, the dispersibility in water is good, but the mechanical strength may deteriorate. If the length is more than 10 mm, the fibers are not easily dispersed in the paper making process, If it is not used as a separation membrane, it may cause defects such as short-circuit.

Preferably, the first backing may comprise one or more materials selected from the group consisting of polyolefins and polyesters and / or marine and / or divider relative to conventional soil components.

On the other hand, any one or more components of the polyolefin and the polyester may include 20 to 70 parts by weight of fibrids with respect to 100 parts by weight of the composite fibers. If the content of the fibrids exceeds 70 parts by weight, the permeability and the ion exchange capacity of the membrane may be deteriorated. If the content of the fibrids is less than 20 parts by weight, the binding effect may be deteriorated and mechanical strength may be deteriorated.

On the other hand, the first and second materials to be used in the present invention may include water, a surfactant, and the like, which may ordinarily be included in the soil component.

The second feedstock used in the present invention comprises an aramid component. Specifically, as used herein, the term aramid refers to a polyamide in which at least 85% of the amide (-CONH-) linkages are directly bonded to two aromatic rings. Additives may be used with the aramid, up to about 10% by weight of other polymeric materials may be blended with the aramid, or the diamine of the aramid may be replaced by about 10% by weight of the other diamine, or the diacid chloride of the aramid may be mixed with 10% May be used. To this end, the aramid component may comprise at least one polymer selected from the group consisting of meta-aramid, para-aramid and meta-paraaramide.

Preferably, the meta-aramid is selected from the group consisting of poly (metaphenylene isophthalamide), poly (m-benzamide), poly (m-phenylene isophthalamide), poly (m, m'-phenylenebenzamide) And poly (1,6-naphthylene isophthalamide), and the para-aramid may be at least one selected from the group consisting of poly (paraphenylene terephthalamide), poly (p-phenylene p, p ' (Biphenyl dicarboxamide), poly (p-phenylene 1,5-naphthylene dicarboxamide), poly (trans, trans-4,4'-dodecahydrobiphenylene terephthalamide), poly Poly (1,4- [2,2,2] -bicyclooctyleneterephthalamide), poly (p-phenylene 4,8-quinolinedicarboxamide) Poly (p-phenylene-4,4'-trans-stilbene carboxamide) and poly (p-phenylene 4,4'-azoxybenzene dicarboxamide / terephthalamide) Acetylenedicarboxylic acid) Which may be equal to or greater than one, the metadata property is selected from the group para-aramid may be poly (meta-phenylene terephthalamide).

Preferably, the second material may comprise aramid fibrids and / or aramid flocs, more preferably 60 to 200 parts by weight of aramid flock relative to 100 parts by weight of the aramid fibrids. If the content of the aramid floc is less than 60 parts by weight, the permeability and strength of the membrane may be deteriorated. If the amount is more than 200 parts by weight, the mechanical strength may decrease and the thickness may increase.

Next, as the step (2), the first stock and the second stock charged through the head box are communicated to the respective material inlets and conveyed through the divided passages. The flow path defined in the present invention includes all of the constitutions in which the flow paths are formed independently or the barrier ribs are formed in one flow path so that the supplied materials are not mixed.

Preferably, the first stock material is conveyed through the central passage 112, and the second stock material is conveyed through the oil passages 111 and 113 formed at the upper and lower portions of the central passage 112, respectively. At this time, the first material can be prevented from accumulating through the rectifying rolls (400, 500), and the turbulence can be reduced, so that the profile of the feed velocity can be made uniform. Although the rectifying rolls 400 and 500 are shown only in the central flow path 112, other flow paths 111 and 113 may also be provided with a rectifying roll.

Next, in step (3), the two or more materials discharged from the two or more flow paths are combined and discharged from one nozzle to form a multi-layer wet paper. Specifically, since the first material and the second material can be easily deformed, when the first material and the second material are joined together in a narrow nozzle flow path, a pressure difference between the first and second materials A mixed layer in which the components are mixed is formed. The interlayer bonding force and strength can be remarkably increased through the formed mixed layer, and the thickness of the separation membrane can be reduced. As a result, the mounting efficiency of the battery is remarkably improved, and the battery can be usefully used in a high capacity battery. On the other hand, the thickness of the mixed layer can be appropriately adjusted by adjusting the pressure of the charged materials, the diameter of the flow path and the diameter of the nozzle, the discharge speed of the nozzle, and the speed of the wire net.

In the next step (4), the multi-layer wet paper is compressed to produce a separation membrane. The compression method that can be applied to the present invention may be a calendering process in which the calendering process can be performed at a compression temperature of 250-320 ° C and a line pressure of 50-400 kgf / cm.

Thereafter, preferably, in step (5), the produced separation membrane is subjected to a reduction treatment to form a microfiber in the separation membrane. At this time, depending on the kind of the usable polymer and / or the water-soluble polymer of the conjugated fiber used, the aqueous solution and the water treatment may be suitably used. If an aqueous alkaline solution is used, the polymer can be eluted using a 1-5% aqueous sodium hydroxide solution. The monofilament fineness of the microfine yarn thus produced may be 0.01-0.2 denier.

Also, the step (5) may be performed before the step (4). In this case, after the production of the multi-layered wetland, it is subjected to the reduction process and then the multi-layered wetland is compressed to produce the membrane.

The aramid multilayer paper separation membrane of the present invention produced by the above-described production method comprises at least one component (1) of a polyolefin and a polyester, and the component (1) comprises at least one of polyolefin And a porous second layer comprising a first layer and an aramid formed on at least one side of the first layer; And a porous first mixed layer in which a first layer component and a second layer component are mixed between the first layer and the second layer.

6 is a cross-sectional view of an aramid multi-layered paper separating film 300 according to an embodiment of the present invention in which a first mixed layer 304 and a second mixed layer 305 are formed on upper and lower portions of a first layer 301, A second layer 302 is formed on the first mixed layer 304. The third layer 303 is formed on the lower surface of the second mixed layer 305.

First, the first layer 301 is a porous layer containing at least one component (1) of a polyolefin and a polyester, and includes a microfiber layer containing any one of polyolefin and polyester components therein. The first layer may be a polymer layer commonly used in a paper separating film for a battery. In the present invention, the first layer may further include a micro-fiber including at least one of polyolefin and polyester. As a result, the porosity and the ion exchange capacity of the separator can be remarkably improved and the charging efficiency can be remarkably improved, so that the separator can be suitably used for a large capacity high efficiency battery.

Preferably, the first layer 301 contains 50 to 90% by weight of the microfibers. If the content of the microfine yarns is less than 50% by weight, the lowering of the air permeability may occur. If the content is more than 90% by weight, the binding effect of fibrids may be deteriorated.

The microfine yarn used in the present invention may have a single yarn fineness of 0.01 to 0.2 denier. If the monofilament fineness is less than 0.01 denier, the stiffness of the denier fiber may be lowered and the structure in the paper may be destroyed. If the denier exceeds 0.2 denier, the pore volume of the separation membrane itself may decrease.

Preferably, the length of the microfibers can be 1 to 10 mm. If the length is less than 1 mm, the mechanical characteristics may be deteriorated. If the length is more than 10 mm, the fibers may aggregate to form a satisfactory result, which may result in nonuniformity in ion exchange.

In the present invention, the thickness of the first layer may preferably be 3 to 8 占 퐉.

Next, the second layer 302 and the third layer 303 will be described. In the present invention, both the second layer 302 and the third layer 303 include a layer containing an aramid component, and the second layer 302 and the third layer 303 may be the same or different components. Specific aramid components are as described above. The thicknesses of the second layer and the third layer may each be 3 to 8 탆.

Next, the first mixed layer 304 and the second mixed layer 305 will be described. The first mixed layer 304 is a mixture of the components of the first layer 301 and the second layer 302 and the second mixed layer 305 is a mixture of the first layer 301 and the third layer 303, Are mixed. Specifically, in the manufacturing process described above, the first and second finishing materials can be easily deformed. Therefore, when the first and second finishing materials are lapped in a narrow nozzle flow path, A mixed layer in which two components are mixed is formed between the ground layer and the ground layer. The interlayer coupling force can be remarkably increased through the formed mixed layer. The thickness of the mixed layer can be appropriately adjusted by adjusting the pressure of the charged materials, the diameter of the flow path and the diameter of the nozzle, the discharge speed of the nozzle, and the speed of the wire net.

The thickness of the first mixed layer 304 and the second mixed layer 305 may be appropriately adjusted, and may be preferably 2 to 5 탆. If the thickness of the mixed layer is less than 2 mu m, the interlayer coupling force may decrease. If the thickness of the mixed layer is more than 5 mu m, the middle layer may not have a sufficient ratio and the shut-down function may be lost.

The thickness of the aramid multilayer paper separation membrane of the present invention is less than 25 μm when the aramid layer is formed on both sides of the first layer. If the aramid multilayer paper separation membrane is more than 25 μm, the size of the secondary battery may be significantly increased.

 While the five-layer structure has been described above, a three-layer structure can be formed when the third layer is not present. Further, it is also apparent to those skilled in the art to further insert various layers or to add various materials on or between the layers of the separator of the present invention.

The thickness of the aramid multilayer paper separation membrane of the present invention is 12 to 20 μm, the tensile strength is 2200 gf / 15 mm or more, the air permeability is 50 to 300 sec / 100 ml, and the resistance value is 0.5 to 1.5 Ω.

As a result, the interlaminar bond strength of the aramid multilayer paper separation membrane can be remarkably improved and the thickness of the separation membrane can be reduced, thereby significantly improving the packaging efficiency of the battery. In addition, the ion exchange capacity is maximized, and at the same time, the shut-down function can be sufficiently exhibited and the charging efficiency is high, so that it can be applied to a high-capacity high-efficiency battery.

Hereinafter, the structure and effect of the present invention will be described in more detail with reference to examples and comparative examples. However, this embodiment is only an example for explaining the present invention in more detail, and the scope of the present invention is not limited to these embodiments.

≪ Example 1 >

A polyester dope (PET Dope) having an intrinsic viscosity of 0.62 was prepared, and a polyester pulp (fibrid) having a freeness of 250 ml was prepared using a fibrid production apparatus.

The sea surface was made of alkali co-PET and the drawing was made of PET and 4 denier chart paper (number of islands 150) was made, and the fiber length was shortened to 3 mm to make short fibers. The fineness of the island component was 0.02 denier. Then, the fibrids and chart marks were mixed in water at a weight ratio of 2: 8, and the mixture was added so as to be 4 wt% with respect to water to prepare a first finishing material.

(2) Manufacture of second material

A meta-aramid (polymethaphenylene isophthalamide) dope (mA Dope) having an intrinsic viscosity of 1.5 was prepared and a meta-aramid fibrid having a Canadian Standard Freeness of 150 ml was manufactured using a fibril production apparatus Respectively. The prepared fibrids were adjusted to 0.8% concentration using a double disk refiner to improve the processability of the wet nonwoven fabric and to improve the physical properties of the final separator, thereby adjusting the freeness of the fibrids to 80 ml.

On the other hand, a 2.0 denier fiber was produced by using the same polymer, and then floc was produced by cutting the fiber length to 3 mm. The strength of the floc was 5.3 g / de and elongation was 35%.

Then, the fibrids and flocs were mixed in water at a weight ratio of 6: 4, and the resultant mixture was added so as to be 4 wt% with respect to water to prepare a second feedstock.

(3) Preparation of aramid paper separator

The first stock and the second stock were put into the paper making apparatus of Fig. 2, respectively. The first stock material was charged into the central charging port 102b and the second stock material was charged into the charging ports 101b and 103b at the upper and lower ends, respectively. The thickness ratio of Lb: La: Lc in the discharge port of FIG. 3 was adjusted to 3.5: 3: 3.5 and discharged. A first mixed layer and a second mixed layer were formed in the discharged multilayer wet paper. Thereafter, the membrane was thermally compressed and processed at a temperature of 290 ° C and a linear pressure of 200 kgf / cm on a calender to prepare a separation membrane. The separation membrane was immersed in 3% NaOH solution for 30 minutes to prepare an aramid paper separation membrane having a thickness of 16 μm. Mixed layers were observed in the prepared membranes.

≪ Example 2 >

A four-denier split yarn (10 split faces) having an elongation plane of CO-PET and an insoluble output face of PET (0.4 denier of mono yarn) was produced in place of the sea chart of Example 1, 3 mm in thickness to obtain a short fiber, and the same procedure as in Example 1 was carried out to prepare an aramid paper separating membrane having a thickness of 18 탆. Mixed layers were observed in the prepared membranes.

≪ Comparative Example 1 &

Except that 50 wt% of PET fibrids and 50 wt% of PET staple fibers (strength: 4.5 g / de, elongation: 30%, 1.5 denier, fiber length: 3 mm) were mixed in the second stock material of Example 1 1 to prepare an aramid paper separating membrane having a thickness of 20 탆. Mixed layers were observed in the prepared membranes.

≪ Comparative Example 2 &

The separator was prepared by charging the multilayer paper machine having three head boxes using the first and second materials of Comparative Example 1. However, due to the minimum weight limit produced by each headbox, it is not possible to produce 25 g / m ² of the final target weights of the laminated membranes. The upper and lower layers have a basis weight of 20 g / m ² and the middle layer has a basis weight of 25 g / m ^{2 2} , and then each wet paper produced is superimposed on the paper to prepare a paper sheet Pressure separation was carried out in the same manner as in Example 1 to prepare a separation membrane having a thickness of 50 탆. No mixed layer was observed in the prepared membrane.

≪ Comparative Example 3 &

The polyester staple fibers used in Comparative Example 1 and the meta-aramid flocks and staple fibers used in the second staple were mixed in a ratio of 4: 3: 3, respectively. The paper was put into a head box of a paper machine to prepare a base paper having a basis weight of 25 g / m ² and thermally compressed under the same conditions as those of the examples to prepare a 24 탆 thick separator.

<Experimental Example>

The following properties of the membranes of Examples 1 to 2 and Comparative Examples 1 to 3 were evaluated, and the results are shown in Table 1.

1. Basic Properties

Thickness D5947-96, tensile strength and elongation ASTM D882, shrinkage ASTM D1204, air permeability ASTM D726, resistance ASTM D7148. The inverse value of the resistance value means the ion exchange ability.

2. Shutdown function and thermal stability

In order to indirectly confirm the shutdown function and the thermal stability of the separators prepared respectively in Examples and Comparative Examples, secondary batteries were manufactured using each of the separators and heat was applied to the secondary batteries to 200 ° C, Respectively. The secondary battery internal resistance at 20 캜 was considered to have a shutdown function when the ratio of the secondary battery internal resistance at 140 캜 was 4 or more and the internal resistance of the secondary battery until the temperature rises from 140 캜 to 170 캜 It was judged that there was a first thermal stability. When the internal resistance of the secondary battery did not decrease even after the temperature rises from 170 ° C to 200 ° C, it was judged that the secondary thermal stability was present.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thickness (um) 16 18 20 50 24 Porosity (%) 58 49 44 35 42 Air permeability (sec / 100ml) 80 230 440 1150 380 Tensile strength (gf / 15 mm) 2310 2470 2500 3600 1350 Elongation (%) 9.3 8.2 9.5 8.8 4.9 Resistance (Ω) 0.55 0.9 1.5 3.7 1.9 Shutdown function ○ ○ ○ ○ X Primary thermal stability ○ ○ ○ ○ △ Secondary thermal stability ○ ○ ○ ○ △

As can be seen from Table 1, the membranes of Examples 1 and 2 of the present invention are significantly superior to the membranes of Comparative Examples 2 and 3 in thickness, porosity, air permeability, tensile strength, resistance value, shutdown function and thermal stability can confirm. Also, it can be confirmed that the thickness is thinner and the resistance value is low and the porosity is high as compared with Comparative Example 1 which does not include microfine yarn.

Can be widely used in the field of the aramid multilayer paper separator cell of the present invention, particularly as a separation membrane of a high capacity secondary battery.

100: Headbox 101, 102, 103: Container
111, 112, 113: Passages 120, 130:
121, 131: roller 200: passage case
210, 220: partition wall 300: multilayer separator paper
400, 500: Rectification roll

Claims (21)

(1) A paper making apparatus comprising one head box having three or more divided paper input ports, comprising at least one component (1) of a polyolefin and a polyester, wherein the component (1) And a second stock comprising an aramid component, the method comprising:
(2) the first and second materials charged through the head box communicate with the respective material input ports and are transported through the divided channels;
(3) combining the two or more feeds discharged from the two or more flow paths to form a multi-layer wet paper by being discharged from one nozzle; And
(4) compressing the multi-layered wetland,
Wherein a first feedstock is charged into an intermediate material input port of the three or more divided feed ports, and a second feedstock is fed into the upper and lower feed ports, respectively. delete delete The method according to claim 1,
Wherein the second support comprises at least one polymer selected from the group consisting of meta-aramid, para-aramid, and meta-para-aramid. 5. The method of claim 4,
The meta-aramid may be selected from the group consisting of poly (m-phenylene isophthalamide), poly (m-benzamide), poly (m-phenylene isophthalamide) 1,6-naphthylene isophthalamide, and 1,6-naphthylene isophthalamide. The method for producing an aramid multilayer paper separation membrane according to claim 1, 5. The method of claim 4,
The para-aramid may be selected from the group consisting of poly (paraphenylene terephthalamide), poly (p-phenylene p, p'-biphenyldicarboxamide), poly (p- , Poly (trans-trans-4,4'-dodecahydrobiphenylene terephthalamide), poly (trans-1,4-cinnamamide), poly (p-phenylene 4,8-quinolinedicarboxamide) , Poly (1,4- [2,2,2] -bicyclooctyleneterephthalamide), copoly (p-phenylene 4,4'-azoxybenzene dicarboxamide / terephthalamide), poly (p -Phenylene-4,4'-trans-stilbenecarboxamide) and poly (p-phenylene acetylene dicarboxamide). The present invention relates to a process for producing an aramid multilayer paper separation membrane Way. 5. The method of claim 4,
Wherein the meta-para-aramid is poly (metaphenylene terephthalamide). The method according to claim 1,
Wherein the polyolefin is at least one selected from the group consisting of polyethylene and polypropylene, polybutene and polymethylpentene, and the polyester is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate Wherein the at least one aramid multi-layered paper separating film has a thickness of 100 mu m or more. The method according to claim 1,
Wherein the second finishing material comprises 60 to 200 parts by weight of aramid flakes with respect to 100 parts by weight of the aramid fibrids. The method according to claim 1,
Wherein the composite fiber comprises 20 to 70 parts by weight of fibrids with respect to 100 parts by weight of the composite fibers. The method according to claim 1,
Wherein the nozzle is narrowed toward the discharge end. The method according to claim 1,
And a pair of rectifying rolls rotated in opposite directions to at least one of the flow paths. The method according to claim 1,
Further comprising the step of forming the microfiber by reducing the amount of the composite fibers after the step (3), the step (4), or the step (4). The method according to claim 1,
Wherein the length of the chart and division yarns is 1 to 20 mm. The method according to claim 1,
Further comprising the step of thermally pressing the aramid multilayer paper separation membrane after the step (4). (1) comprising at least one of a polyolefin and a polyester, wherein the component (1) comprises a porous first layer comprising at least one of a polyolefin and a polyester,
And a porous second layer comprising an aramid formed on at least one side of the first layer;
And a porous first mixed layer in which a first layer component and a second layer component are mixed between the first layer and the second layer. 17. The method of claim 16,
Wherein the microfine fiber has a fineness of 0.01 to 0.2 denier. 17. The method of claim 16,
Wherein the second layer comprises at least one polymer selected from the group consisting of meta-aramid, para-aramid, and meta-paraaramide. 17. The method of claim 16,
Wherein the thickness of the first layer is 3 to 8 占 퐉, the thickness of the first mixed layer is 0.5 to 5 占 퐉, and the thickness of the second layer is 3 to 8 占 퐉. 17. The method of claim 16,
And a porous third layer comprising aramid on the other side of the first layer having the second layer formed thereon; Further comprising a porous second mixed layer in which a first layer component and a third layer component are mixed between the first layer and the third layer. 21. The method of claim 20,
Wherein the aramid multilayer paper separation membrane has a thickness of 12 to 20 탆, a tensile strength of 2200 gf / 15 mm or more, an air permeability of 50 to 300 sec / 100 ml, and a resistance value of 0.5 to 1.5 Ω.

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