KR101446442B1 - Fiber for Secondary Batteries and Separator for Secondary Batteries Comprising the Same - Google Patents

Abstract

The present invention relates to a fiber for a secondary battery and a separator for a secondary battery and, more specifically, to a fiber for a secondary battery characterized by being a fiber for a secondary battery having copolymerized polyester dispersed in a lyotropic polymer, wherein the copolymerized polyester is formed by copolymerizing 60-80 wt% of a terephthalic acid (TPA) and 20-40 wt% of ethylene glycol (EG), and single yarn fineness of the copolymerized polyester after elution of the lyotropic polymer is 0.001-0.3 denier; and to a separator for a secondary battery including the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fiber for a secondary battery and a separator for a secondary battery including the fiber,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber for a secondary battery applicable as a main fiber or a binder fiber of a separation membrane for a secondary battery and a separation membrane for a secondary battery comprising the same.

There are three main types of cells: chemical, physical, and biological. The chemical cells are divided into primary cells, secondary cells, and fuel cells. Primary cells consist of chemically stored electricity. Zinc manganese batteries, alkaline batteries, lithium primary batteries, air-zinc batteries, etc. are used only. Rechargeable batteries are different from primary batteries which are used once and used. And has a cathode active material and a negative active material which is a reducing agent. There is an electrolyte between the anode and the cathode which enables the oxidation reaction and the reduction reaction by ion conduction, and a separation membrane which prevents direct contact between the anode and the cathode.

A separation membrane is a selective obstacle existing between two different materials and means a material that selectively passes or excludes a substance. In other words, when the oxidant and the reducing agent, which are the charge substances of the battery, are in direct contact with each other, the self-discharge causes a rapid reaction. Therefore, the separator is in danger of being in contact with the anode and the cathode.

The separator material of the secondary battery is slightly different depending on the type of the secondary battery. The lead-acid battery is made of polyethylene nonwoven fabric and glass mat, and the small sealed lead-acid battery is made of glass mat. The nickel-cadmium battery and the nickel-metal hydride battery use a polyamide corrosion film and a polypropylene corrosion cell. The lithium ion battery uses a polypropylene microporous film as a vanadium lithium battery, a manganese lithium battery, and a vanadium niobium lithium battery as a polypropylene microporous film and a polypropylene non- Is used.

Conventionally, it has been difficult to manufacture a long fiber of the direct spinning method because it is impossible to produce a single filament fineness (DPF: Denier Per Filament) of 0.3 denier or less, which is difficult to use for a binder fiber of a separation membrane for a secondary battery. For this reason, staple fiber was used. Staple fiber can be produced with a single fiber fineness of 0.3 denier or less, but the minimum and maximum deviation of single fiber fineness is 10 times or more due to the characteristics of Staple Fiber. Due to such a problem, when used as the binder fiber of the secondary battery separator, there is a variation in performance and the strength is lowered.

Accordingly, the development of techniques for main fibers and binder fibers having physical properties suitable for application to separation membranes of secondary batteries is continuing.

An object of the present invention is to provide a secondary battery fiber having excellent strength so that it can be used as a main fiber or a binder fiber of a secondary battery separator and a method of manufacturing the same.

The present invention also provides a separation membrane for a secondary battery comprising a main fiber or a binder fiber having excellent strength.

Accordingly, the present invention provides, as a first preferred embodiment, a fiber for a secondary battery in which copolymerized polyesters are dispersed and arranged in a usable polymer, wherein the copolymerized polyester is TPA (Terephthalic Acid) 60 To 80% by weight of ethylene glycol, and 20 to 40% by weight of EG (Ethylene Glycol), and the single fiber fineness of the copolymerized polyester is 0.001 to 0.3 denier after the release of the usable polymer.

The copolyester according to this embodiment may have an intrinsic viscosity (I V) of 0.55 to 0.75.

The copolymerized polyester according to the embodiment includes 60 to 77% by weight of TPA (Terephthalic Acid); 20 to 37% by weight of EG (Ethylene Glycol), and 0 to 3% by weight of at least one catalyst selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate.

The usable polymer according to this embodiment may be selected from copolymerized polyester, polyvinyl alcohol and polystyrene.

The usable polymer according to this embodiment is a copolymer obtained by copolymerizing 0.5 to 15% by weight of 5-sodium dimethyl isophthalate (DMIS) and 4 to 25% by weight of polyethylene glycol having a number average molecular weight of 8000 or more with respect to 60 to 90% by weight of the polyethylene terephthalate component And the like.

The secondary battery fiber according to the embodiment may be a main fiber for a secondary battery or a binder fiber.

The present invention also provides, as a second preferred embodiment, a separation membrane for a secondary battery comprising the fiber.

The present invention also provides, as a third preferred embodiment, a process for producing a usable polymer selected from the group consisting of (S1) copolymerized polyester, polyvinyl alcohol and polystyrene; (S2) 60 to 80% by weight of TPA (Terephthalic Acid) and 20 to 40% by weight of EG (Ethylene Glycol) to prepare a copolymerized copolymer polyester; And (S3) spinning the usable polymer and the co-polyester.

The step (S1) according to the embodiment may include a step of mixing 0.5 to 15% by weight of 5-sodium dimethyl isophthalate (DMIS) and 4 to 25% by weight of polyethylene glycol having a number average molecular weight of 8000 or more with respect to 60 to 90% by weight of the polyethylene terephthalate component And the step of producing the usable polymer which is a copolymerized copolymer polyester.

The copolyester copolymerized in the step (S2) may have an intrinsic viscosity of 0.55 to 0.75.

The copolymerized polyester according to the embodiment includes 60 to 77% by weight of TPA (Terephthalic Acid); 20 to 37% by weight of EG (Ethylene Glycol), and 0 to 3% by weight of at least one catalyst selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate.

The secondary battery fiber according to the embodiment may be a subject fiber for a secondary battery or a subject fiber for a secondary battery.

The fiber of the present invention has excellent strength and is useful as a main fiber and a binder fiber of a separation membrane for a secondary battery.

Hereinafter, the present invention will be described in detail.

The present invention relates to a fiber for a secondary battery in which copolymerized polyesters are dispersed and arranged in a usable polymer, wherein the copolymerized polyester comprises 60 to 80% by weight of TPA (Terephthalic Acid) and 60 to 80% by weight of EG Glycol) in an amount of 20 to 40% by weight, and the monofilament fineness of the copolymerized polyester after the release of the usable polymer is 0.001 to 0.3 denier.

The secondary battery fiber according to the present invention may be a primary fiber or a secondary fiber of a separation membrane for a secondary battery. The primary fiber serves as a skeleton forming a separation membrane for a secondary battery, and the binder fiber is filled in the primary fibers And serves to connect the main fibers, thereby finally forming a secondary battery separator.

In this case, the main fibers and the binder fibers have the same composition. After the fibers are produced, they are divided into main fibers and binder fibers by a usual post-process applied to the main fibers and the binder fibers for secondary batteries, And may be used to form a secondary battery separator depending on its role.

Specifically, the copolymer polyester may have an intrinsic viscosity (I V) of 0.55 to 0.75.

The method for producing the secondary battery fiber comprises the steps of: (S1) preparing a usable polymer selected from the group consisting of copolymerized polyester, polyvinyl alcohol and polystyrene; (S2) a step of preparing copolymerized polyester copolymerized with 60 to 80% by weight of TPA (Terephthalic Acid) and 20 to 40% by weight of EG (Ethylene Glycol); And (S3) spinning the usable polymer and the co-polyester.

The secondary battery fiber of the present invention may be in the form of a sea-island complex fiber in which the polymer is used as a sea component and the copolymerized polyester is used as a conductive component, and these fibers are compounded and spun in sea-island form.

The secondary battery fiber of the present invention includes two components, and includes a polymer used as a first component and a copolymerized polyester as a second component.

The polymer used as the first component of the present invention may further contain sodium acetate in an amount of more than 0 ppm and not more than 3000 ppm as an anti-aggregation agent, and when sodium acetate is contained in an amount of more than 3000 ppm, sodium acetate remains as impurities in the polymer, And the yarn strength is lowered, making it difficult to use as a fiber.

The copolymerized polyester as the second component may be a two-component copolymer polyester obtained by copolymerizing 60 to 80% by weight of TPA (Terephthalic Acid) and 20 to 40% by weight of EG (Ethylene Glycol), 60 to 77% by weight of TPA (Terephthalic Acid) %; 20 to 37% by weight of ethylene glycol (EG), and 3% by weight or more and 3% by weight or more of at least one catalyst component selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate.

In other words, the copolyester used as the second component in the present invention is a copolymer obtained by copolymerizing EG with TPA as a main component or by copolymerizing EG with TPA as a main component and at least one catalyst selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate May be copolymerized.

When the copolymerized polyester used as the second component is a two-component copolymerized polyester obtained by copolymerizing 60 to 80% by weight of TPA (Terephthalic Acid) and 20 to 40% by weight of EG (Ethylene Glycol), the copolymerization amount of TPA and EG , The spinning workability is poor and the physical properties of the yarn are deteriorated or there is a fear of dissolving the co-polyester component as the second component in the usable polymer elution step as the first component.

Also, the copolymer polyester used as the second component is 60 to 77% by weight of TPA (Terephthalic Acid); 20 to 37% by weight of ethylene glycol (EG), and 3% by weight or more but not more than 3% by weight of any one or more selected catalysts selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate are copolymerized with TPA If the copolymerization amount of EG exceeds the above range, there is a fear of poor spinning operability and deterioration of the physical properties of the yarn or elution of the co-polyester component as the second component in the usable polymer elution step as the first component, The copolymerization can be smoothly carried out.

The intrinsic viscosity (IV) of the second component may be 0.55 to 0.75. If the intrinsic viscosity of the copolymer is less than 0.55, the intrinsic viscosity of the copolymer may be low, It is difficult to manufacture the paper because it can not function as main fiber or binder fiber because it does not dissolve in the paper making process.

The strength of the copolymer polyester as the second component after the release of the usable polymer as the first component may be 1.0 to 6.0 (g / de). If the strength is less than 1.0 g / de, And the yield was low.

On the other hand, it is preferable that the single component monofilament degree of the copolymer polyester as the second component after the release of the usable polymer as the first component is 0.001 to 0.3 denier. When the monoclinic polyester single-fiber fineness as the second component after the leaching of the usable polymer which is the first component is more than 0.3 denier, it is possible to produce by the direct spinning method instead of the sea-island conjugate fiber method, This is good. When the monofilament fineness of the copolymer polyester as the second component is less than 0.001 denier, it is not suitable for the secondary battery separator because the fibers are entangled in the paper making process after elution and the strength is weak due to the poor mixing with the main fiber and the physical properties are large. .

On the other hand, the usable polymer as the first component stabilizes the shape of the copolymer polyester as the second component in the spinning and increases the strength retention ratio of the yarn after the release of the polymer by using the first component, It is most preferable to use a copolymer polyester having a high alkaline elution rate as a sea component in order to minimize it. If the dissolution rate of the usable polymer as the first component is high, the dissolution temperature, the residence time, and the alkali concentration are reduced, resulting in cost reduction and improved productivity. As a specific example, a usable polymer having a blend of (a) a co-polyester in which an ester unit containing a metal sulfonate is copolymerized with an ester unit of ethylene terephthalic acid as a main component, and (b) a polyethylene glycol having a number average molecular weight of 8,000 or more can be used .

At this time, 0.5 to 15% by weight of 5-sodium dimethyl isophthalate (DMIS) and 4 to 25% by weight of polyethylene glycol having a number average molecular weight of 8000 or more are copolymerized with 60 to 90% by weight of the polyethylene terephthalate component as the main raw material in the above- And the like. If the content of polyethylene glycol is less than 4% by weight, the dissolution rate of the usable polymer, particularly the initial dissolution rate may be slowed. If the content of the polyethylene glycol is more than 25% by weight, .

The content of the ester unit containing the metal sulfonate in the copolymer polyester as the above-mentioned polymer to be used is preferably 315% by weight. If the content is less than 3% by weight, the dissolution rate of the usable polymer may be lowered and the second component may invade the copolymer polyester. If the content exceeds 15% by weight, the excess copolymer compound The amorphous polymer becomes difficult to form and the manufacturing cost may increase. More preferably, the total amount of the copolymerized compound and the blended compound in the usable polymer is 20 wt% or less based on the total usable polymer weight.

Polyvinyl alcohol or polystyrene, which is water-soluble, may also be used as the polymer. In the case of using polystyrene, a problem of environmental pollution occurs because a solvent is required to be used for the release of the polymer.

The cationic fluorine-containing copolymerizable polyester as the second component of the secondary battery fiber of the present invention and the polymer used as the first component can be produced by composite spinning using a common composite spinning apparatus. At this time, the main fiber or the binder fiber can be produced by direct spinning by spinning at a high spinning speed, and the main fiber and the binder fiber in an unoriented or semi-stretched state can be manufactured at a spinning speed of 1,500 to 8,000 m / It is possible.

It is preferable to adjust the monofilament fineness of the main fiber or the binder fiber used for the polymer in the range of 1 to 7 denier in order to improve the skeletal role or the binder role in paper making. The spinning, stretched main fibers and binder fibers may be subjected to a false twisting process by a normal twisting process.

The main fiber or the binder fiber of the present invention and the false-twist yarn of the present invention are subjected to a weight reduction treatment in an aqueous alkali solution or water, and they are mixed with each other or used alone.

On the other hand, the main fiber or the binder fiber of the present invention and the false-twist yarns thereof are interlaced with the highly hydrous polyester yarn to produce a composite yarn, which is then mixed with the main fiber or binder fiber of the separation yarn for weaving, May be used.

Particularly, the separator for a secondary battery manufactured by the secondary battery fiber produced in accordance with the present invention can reduce the thickness of the separator, compared to a general polyester yarn, due to the morphological characteristics of the sea-island composite yarn.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

Example 1

As the usable polymer as the first component, 5 wt% of 5-sodium dimethyl isophthalate (DMIS) was copolymerized with 83 wt% of the polyethylene terephthalate component, and 12 wt% of polyethylene glycol having a number average molecular weight of 9000 was blended with IV 0.60 And the polymer was used.

A copolymer polyester of IV 0.57 in which 1 wt% of at least one catalyst selected from the group consisting of 74% by weight of TPA, 25% by weight of EG, titanium dioxide, antimony trioxide and trimethyl phosphate was copolymerized as the second component, Respectively. The intrinsic viscosity of the copolymer polyester as the second component and the monoclinic degree of fineness of the copolymer polyester as the second component after elution of the usable polymer as the first component are as shown in Table 1.

The first component and the second component, that is, the copolymer polyester, are supplied to a conventional composite spinning apparatus, and the weight ratio of the first component to the second component is 3: 7, and the main fiber of 80 denier / 25 filaments .

The first component had a spin-beam temperature of 270, the second component had a spin-beam temperature of 290, detached 130 / 0.2D * 0.6L, a circular 25Hole, and 35 pipes per 1Hole. The winding speed was 3,700mpm. 1Godet Roller 1,500mpm, 90-5.5 turn, 2nd Goodet Roller 3,760mpm, 130 to 4.5 turn condition.

The binder fiber for the secondary battery was 0.21 dtex in thickness and 3.1 mm in length. Staple fiber was used. IV was 0.380, TiO2 was 2500 ppm, SIPE content was 3.8 mol%, and Melting Point was 245.

Examples 2 to 8

As shown in Table 1, the main fiber and the binder fiber were prepared in the same manner as in Example 1, except that the intrinsic viscosity of the copolymer polyester as the second component was changed.

Comparative Example 1 and Comparative Example 4

As shown in Table 1, the main fiber and the binder fiber were prepared in the same manner as in Example 1, except that the intrinsic viscosity of the copolymer polyester as the second component was changed.

The secondary fibers and the binder fibers prepared in Examples and Comparative Examples were subjected to ordinary post-processes to prepare a secondary battery separation membrane. A usual post-process means a cutting process, a usable polymer elution process, a mixing process, a drying process in a drum dryer, and a winding process.

In the post-process, the prepared main fiber and the binder fiber are cut to an appropriate length through a cutting process, respectively, and then the resulting polymer is eluted. Thereafter, the binder fiber and the main fiber are mixed together with a dispersant to form a separation membrane, and then a drying process is performed to dry the separation membrane in a drum dryer. Then, the separation membrane is wound on the roller To prepare a secondary battery separator.

As described above, the separation membranes for secondary batteries were prepared by using the main fibers and the binder fibers produced in the examples and the comparative examples by the conventional method, and then the finenesses, the strengths, the deniers / The tensile strength of the cast and grass (separator) was measured, and the results are shown in Table 1.

(1) Fineness (denier)

KS K 0415 method.

(2) Strength

KS K 0412 method.

(3) Denier / strength after elution

 70 thermostat The denier and the strength of the fiber dried in a 5% aqueous solution of NaOH for 15 minutes and then rinsed in pure water for 10 times and dried in a closed dryer at 20 for 24 hours were measured.

In this process, the total amount of the usable polymer as the first component was eluted and the fibers of the copolymer polyester as the second component were left.

      (4) The spinning productivity (%) is 5,000kg / 100,000 / 100,000.

(5) Tensile strength of grass (membrane)

ASTM D 828: 1997, CRE method.

division The second component, the copolymer polyester cinnabar
Fineness  Fiber denier  Fiber strength (g / de) Radiation workability
(%) Grass Tensile Strength
(kN / m) IV
(-) reaction
Temperature
() vacuum
(torr) reaction
time
(hr) cinnabar
Fineness Exhibited After elution Exhibited After elution Example 1 0.57 282 1.0 2.8 0.064 3.2 80.0 55.3 4.91 3.83 98.1 0.23 Example 2 0.63 284 0.9 3.0 0.064 3.2 80.0 55.6 4.98 3.85 98.5 0.26 Example 3 0.69 286 0.8 3.2 0.064 3.2 80.0 54.9 4.97 3.84 99.1 0.28 Example 4 0.73 288 0.7 3.4 0.064 3.2 80.0 54.7 5.01 3.90 98.6 0.30 Example 5 0.57 282 1.0 2.8 0.040 2.0 50.0 33.8 5.13 4.01 97.2 0.27 Example 6 0.63 284 0.9 3.0 0.040 2.0 50.0 34.0 5.16 3.99 97.5 0.29 Example 7 0.69 286 0.8 3.2 0.040 2.0 50.0 34.1 5.21 4.05 98.2 0.33 Example 8 0.73 288 0.7 3.4 0.040 2.0 50.0 34.3 5.26 4.10 98.1 0.34 Comparative Example 1 0.53 280 1.1 2.6 0.064 3.2 80.0 54.8 4.75 3.51 75.3 0.08 Comparative Example 2 0.78 290 0.5 3.6 0.064 3.2 80.0 55.5 4.07 3.95 73.2 0.07 Comparative Example 3 0.53 280 1.1 2.6 0.040 2.0 50.0 33.8 5.02 3.91 68.3 0.09 Comparative Example 4 0.78 290 0.5 3.6 0.040 2.0 50.0 34.2 5.31 4.21 65.1 0.05

Claims (12)

In a secondary battery fiber in which copolymerized polyester having an intrinsic viscosity (IV) of 0.55 to 0.75 dl / g is dispersed and arranged in an easy-to-use polymer,
The copolymer polyester having an Intrinsic Viscosity (IV) of 0.55 to 0.75 dl / g is a copolymer of 60 to 80% by weight of TPA (Terephthalic Acid) and 20 to 40% by weight of EG (Ethylene Glycol)
Wherein the single-fiber fineness of the copolymer polyester after the release of the polymer is 0.001 to 0.3 denier.
delete The method according to claim 1,
The copolymer polyester includes 60 to 77% by weight of TPA (Terephthalic Acid); 20 to 37% by weight of EG (Ethylene Glycol), and 0 to 3% by weight of at least one catalyst selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate are copolymerized.
The method according to claim 1,
Wherein the useable polymer is selected from copolymerized polyester, polyvinyl alcohol and polystyrene.
5. The method of claim 4,
The polymer used is a copolymerized poly (ethylene terephthalate) copolymer having a copolymer of 5 to 30% by weight of dimethyl isophthalate (DMIS) and 4 to 25% by weight of polyethylene glycol having a number average molecular weight of 8000 or more, relative to 60 to 90% Wherein the polymer is an ester.
The method according to claim 1,
Wherein the secondary battery fiber is a main fiber for a secondary battery or a binder fiber.
The separator for a secondary battery according to any one of claims 1 to 6, wherein the fiber is in a state in which the polymer is removed.
(S1) preparing a usable polymer selected from the group consisting of copolymerized polyester, polyvinyl alcohol and polystyrene;
(S2) a step of preparing copolymerized polyester copolymerized with 60 to 80% by weight of TPA (Terephthalic Acid) and 20 to 40% by weight of EG (Ethylene Glycol) with an Intrinsic Viscosity (IV) of 0.55 to 0.75 dl / g ; And
(S3) A method for producing a secondary battery fiber, comprising the step of spinning the above-mentioned usable polymer and a copolymer polyester having an Intrinsic Viscosity (IV) of 0.55 to 0.75 dl / g.
9. The method of claim 8,
The step (S1) may include a step of mixing 0.5 to 15% by weight of 5-sodium dimethyl isophthalate (DMIS) and 4 to 25% by weight of polyethylene glycol having a number average molecular weight of 8000 or more based on 60 to 90% by weight of the polyethylene terephthalate component Wherein the step (b) is a step of producing an ester-based polymer.
delete 9. The method of claim 8,
The copolymer polyester includes 60 to 77% by weight of TPA (Terephthalic Acid); 20 to 37% by weight of ethylene glycol (EG), and 0 to 3% by weight of at least one catalyst selected from the group consisting of titanium dioxide, antimony trioxide and trimethyl phosphate are copolymerized. Way.
The method according to any one of claims 8 to 9 and 11 to 12,
Wherein the secondary battery fiber is a subject fiber for a secondary battery or a subject fiber for a secondary battery.