KR100679660B1 - A separator of spun-bonded non-woven fabric, and a method for preparing the same - Google Patents

Abstract

The present invention relates to a spunbonded nonwoven fabric separator for batteries and a method for manufacturing the same, and more particularly, to a spunbonded nonwoven fabric separator for batteries comprising a fine filament divided from split filaments composed of two or more polymer components It is about a method.

Since the spunbonded nonwoven fabric separator for batteries of the present invention includes two or more kinds of polymer components, the advantages of each polymer component play a complementary role, and thus the mechanical strength of the spunbonded nonwoven fabric separator is superior to that of the conventional fine glass fiber separator or the separator using agglomerated silica and polyethylene. And excellent heat resistance, and micropores formed between filaments of fineness cause capillary action and have excellent wettability.

Lead Acid Battery, Separator, Spunbond, Non-Woven Fabric

Description

Spunbonded Non-Woven Fabric Isolation Membrane for Batteries and Manufacturing Method Thereof {A SEPARATOR OF SPUN-BONDED NON-WOVEN FABRIC, AND A METHOD FOR PREPARING THE SAME}

1 is an optical micrograph showing a cross section of a split filament having an orange cross section of 16 divisions.

2 is an optical micrograph showing a cross section of a split filament having a hollow section of 16 divisions.

3 is an optical micrograph showing a cross section of a split filament having a 32 divided chrysanthemum cross section.

Figure 4 is a process chart showing an example of the manufacturing process of the spunbond nonwoven fabric separator for batteries of the present invention.

[Industrial use]

The present invention relates to a spunbond nonwoven separator for batteries and a method for manufacturing the same, and more particularly, to a spunbond nonwoven separator for batteries having excellent strength and heat resistance, and a method of manufacturing the same.

[Private Technology]

In general, lead acid batteries include a positive electrode active material (lead peroxide, PbSO ₄ ), a negative electrode active material (lead, Pb), an electrolyte solution (sulfuric acid, H ₂ SO ₄ ), and a separator, and the separator is disposed between the positive electrode and the negative electrode. It is inserted into the block to prevent direct contact with them, and serves to prevent a short circuit (short) caused by the dropped active material.

In addition, the separator has a pore and has a property of allowing an electrolyte to penetrate into the pore of the separator to allow current to flow between the positive electrode plate and the negative electrode plate. Due to this property, ions generated through the chemical reaction of the positive electrode active material, the negative active material, and the electrolyte solution interact with each other, thereby causing the flow of current.

In addition, the separator assists in discharging gas (H ₂ , O _2, etc.) components generated when the lead acid battery is recharged, and also serves to suppress electrolyte leakage caused by accumulation of gas components in the lead acid battery.

In general, the material used for the separator requires strength to prevent tearing due to the dropped active material and to prevent breakage due to pressure applied during battery manufacturing, and to have uniformly distributed pores and uniform thickness.

Currently used battery separators can be divided into two categories. One of them uses fine glass fibers, which provides high porosity and uniform electrolyte distribution, and the other uses condensed silica, which is called polyethylene isolation membrane.

The polyethylene separator uses silica of several tens of micrometers in order to improve acid wettability and lower electrical resistance of the separator, and uses a polyethylene binder to bond the silica.

In addition, in addition to the separator, a separator in the form of a mixed fiber such as cotton fiber, synthetic fiber, and glass fiber has been used.

The separator has advantages of excellent acid wettability, uniformity of electrolyte distribution, and high porosity, but has some problems with it. First, a separator made of fine glass fibers has a low resistance to breakage, which is not preferable because a lead-acid battery mounted on a moving device such as a vehicle having a lot of activity is likely to cause a short circuit.

Second, in the case of polyethylene separator using condensed silica (US Pat. No. 4,024,323, and Japanese Patent Publication No. 54-143417), it is necessary to increase the content of porous inorganic filler to obtain high porosity, but the content of inorganic filler is large. As the thickness increases, the mechanical strength of the separator decreases, and when the ultrahigh molecular weight polyethylene resin is used to increase the bonding strength, there is a problem that a high porosity cannot be obtained.

Korean Patent Laid-Open Publication No. 2001-005879 describes a method of treating the surface of the inorganic filler in order to solve this problem, but such surface treatment causes a complicated process and increases the manufacturing cost.

In addition, the polyethylene used to bind the porous inorganic filler has a low melting point of its own, resulting in insufficient heat resistance of the separator itself.

Third, the other membranes in the form of mixed fibers, the resin penetrated into the filter paper made of cellulose fibers, such as cotton fibers, pulp, acid resistance is weak, there is a hassle to attach a separate glass fiber to compensate for the insufficient strength.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a spunbond nonwoven fabric separator for batteries excellent in mechanical strength, heat resistance and wettability to the electrolyte.

Another object of the present invention is to provide a method of manufacturing the spunbond nonwoven separator for batteries.

In order to achieve the above object, the present invention provides a battery spunbond nonwoven separator comprising a fine filament divided from the divided filament consisting of two or more polymer components.

The present invention also provides a method for manufacturing a spunbond nonwoven fabric using split filaments composed of two or more polymer components; And separating the filaments of the fineness from the divided filaments of the manufactured spunbond nonwoven fabric.

Hereinafter, the present invention will be described in more detail.

The spunbonded nonwoven separator for batteries of the present invention comprises filaments of fineness divided from split filaments composed of two or more polymer components.

In the present invention, the split filament refers to a filament in which two or more polymer components each have a fine filament form and are contained in one filament.

Since the divided form of the split filament is determined according to the shape of the spinneret, the split filament is not particularly limited, and divided filaments having a cross section of an orange, hollow, chrysanthemum, etc., having 16 to 32 splits are preferable.

1 is an optical micrograph showing a cross section of a split filament having an orange cross section of 16 divisions, FIG. 2 is an optical micrograph showing a cross section of a split filament having a hollow section of 16 divisions, and FIG. It is an optical microscope photograph showing the cross section of a split filament having a split chrysanthemum cross section.

The fineness of the split filament is not particularly limited, but preferably has a fineness of 3 to 5 deniers.

In addition, the type of each polymer component included in the split filament is not particularly limited, but it is preferable that the interface of each component has an incompatible property, and the polyester is included as the first component and the polyolefin is used as the second component. It is more preferable that it is comprised by the two-component system containing.

The weight ratio of the polyester as the first component and the polyolefin as the second component is preferably 20:80 to 80:20, more preferably 30:70 to 70:30. When the weight ratio is less than 20:80, when the content of the first component is small, the effect of improving heat resistance by polyester is reduced. When the weight ratio is greater than 80:20, the content of the first component is polyolefin. The thermal adhesion by the polymer is not easy, resulting in a decrease in strength of the produced spunbond nonwoven fabric.

It is preferable that the polyester which is the said 1st component has melting | fusing point of 200-260 degreeC, and it is preferable that the polyolefin which is the said 2nd component has melting | fusing point of 150-170 degreeC. When the melting point of the first component is less than 200 ° C, the effect of improving the heat resistance is lowered. When the melting point of the first component exceeds 260 ° C, thermal adhesion of the nonwoven fabric is not easy due to a high melting point difference with the polyolefin-based polymer.

The polyester as the first component is preferably polyethylene terephthalate (PET), and the polyolefin as the second component is more preferably polyethylene, polypropylene, or a mixture thereof.

The fineness filament divided from the split filament preferably has a fineness of 0.05 to 0.2 denier. When the fineness of the fineness filament is less than 0.05 denier, the microfiber fibers have a low strength, and thus, problems such as cutting and the formation of suspended particles during the process or use are likely to occur, and when the fineness of the fine filament exceeds 0.2 denier, capillary phenomenon due to the fineness This causes the wetting speed of the electrolyte solution to decrease.

The spunbond nonwoven separator comprising the fineness filament is a nonwoven fabric produced in a spunbond manner and has excellent mechanical strength, and the fine fineness has fine pores between the filaments, resulting in a capillary phenomenon and excellent wettability with respect to the electrolyte.

However, the spunbond nonwoven separator may be a hydrophilic treatment to increase the wettability, the hydrophilic treatment is a group consisting of an aqueous acrylic compound, a urethane compound, a vinyl alcohol compound, and a vinyl acetate compound in the spunbond nonwoven separator It is preferable that it is treated with one or more compounds selected from, or treated with a surfactant or plasma.

The battery spunbond nonwoven separator preferably has a weight per unit area of 30 to 400 g / m ² . When the weight per unit area of the spunbond nonwoven fabric separator is less than 30 g / m ^2, it has a thin thickness, but the mechanical strength is weak, and when the weight exceeds 400 g / m ² , the thickness is thick. You will be constrained.

The spunbonded nonwoven fabric separator for batteries of the present invention may be used as a separator for a primary battery or a secondary battery, and more preferably, for a lead acid battery separator.

The spunbonded nonwoven fabric separator for batteries may include: manufacturing a spunbonded nonwoven fabric using split filaments composed of two or more polymer components; And separating the fine filaments of the fineness from the divided filaments of the manufactured spunbond nonwoven fabric, and may be manufactured according to the method of manufacturing a spunbond nonwoven separator for battery.

Figure 4 is a process chart showing an example of the manufacturing process of the spunbond nonwoven fabric separator for batteries of the present invention. The molten polymer supplied from the extruder 1 passes through the spinning block 2 and is manufactured in the form of a split filament 3. The split filaments are again fixed in the form of a web on the continuous transfer metal network 5 through the high-speed drawing device 4 to form a spunbond nonwoven fabric, and the spunbond nonwoven fabric is again subjected to high pressure air or water. The split filaments are separated into filaments of fineness by passing through the dividing device 6 for spraying the filaments.

The spunbonded nonwoven fabric having undergone the separation process is thermally fused through a device 7 such as calender roll or emboss roll.

The manufacturing of the split filament and the manufacturing of the spunbond nonwoven fabric using the split filament may be performed according to a conventionally known method, and are not particularly limited in the present invention. However, since the details of the split filament used in the manufacture of the spunbond nonwoven fabric are the same as those described above, detailed descriptions thereof will be omitted.

Separation of the fineness filament from the split filament after the fabrication of the spunbond nonwoven fabric may be performed by a method of separating at high pressure by using incompatible properties between the interfaces of each component, preferably the spunbond nonwoven fabric A water punching method can be used to apply a water pressure of 50 to 300 kg.f / cm ² .

When the water pressure applied to the spunbond nonwoven fabric is less than 50 kg.f / cm ^2, the splitting of each polymer component is undesirably difficult to obtain fine fine filaments, and the hygroscopicity of the separator against the electrolyte becomes low. In addition, when the water pressure exceeds 300 kg.f / cm ² , excessive pressure is applied so that the divided fineness filaments are unevenly distributed in the nonwoven fabric, so that the impregnation of the electrolyte required for the separator is partially uneven. .

The method for producing a spunbonded nonwoven fabric separator for a battery of the present invention includes a thermal fusion process for improving the uniformity and strength of the spunbonded nonwoven fabric produced by the above method. It is preferable to use a calender roll or an emboss roll for the said heat fusion process.

It is preferable that it is 120-220 degreeC, and, as for the temperature of the said heat fusion process, it is more preferable that it is 150-200 degreeC. If the heat fusion temperature is less than 120 ℃, the fine strength of the nonwoven fabric is weak because the filaments of the fineness is not adhered, and if the temperature exceeds 220 ℃, the micropores of the spunbond nonwoven fabric due to excessive heat welding of the filaments of the fineness This prevents the movement of ions in the lead acid battery.

The method for producing a spunbonded nonwoven fabric for batteries of the present invention also includes the step of subjecting the prepared spunbonded nonwoven fabric to hydrophilic treatment. The wetting speed of the electrolyte may be improved by the hydrophilic treatment.

The hydrophilic treatment may be performed by treating the spunbond nonwoven fabric with at least one compound selected from the group consisting of an aqueous acrylic compound, a urethane compound, a vinyl alcohol compound, and a vinyl acetate compound, or a surfactant or plasma treatment. desirable. The treatment method includes a foam coating treatment, a gravure coating treatment, a dipping treatment, a spray treatment, or a kiss roll treatment.

Hereinafter, preferred embodiments of the present invention are described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

EXAMPLE

Example  One

A spunbonded nonwoven fabric having a weight per unit area of 100 g / m ² was manufactured using 16 split filaments having a cross-sectional structure as shown in FIG. 2 and having a fineness of 3 denier. The 16-part filament used in the manufacture of the nonwoven fabric includes polyethylene terephthalate (intrinsic viscosity IV = 0.68, melting point = 210 ° C.) as a first component, the second component comprises polypropylene, and A weight ratio of the second component of 20:80 was used.

The filament of the fineness was separated by water punching with water pressure of 200 kg.f / cm ² with respect to the spunbonded nonwoven fabric. The spunbonded nonwoven fabric after the separation of the filaments was heat-sealed by a calender roll (NIP pressure = 85 kg / cm) at 150 ° C.

In addition, the spunbond nonwoven fabric was fabricated with a water-based acrylic binder (BASF Corporation's Acronal series) by a 10% by weight hydrophilic treatment of the nonwoven fabric by a foam coating process to prepare a spunbond nonwoven fabric separator for batteries. .

Example  2

A spunbonded nonwoven fabric separator for batteries was manufactured in the same manner as in Example 1, except that the weight ratio of the first component to the second component was 40:60.

Example  3

A spunbonded nonwoven fabric separator for batteries was manufactured in the same manner as in Example 1, except that hydrophilic processing was performed using a water-dispersed polyurethane binder of Kocam Co., Ltd. (Korea).

Example  4

A spunbonded nonwoven fabric separator for batteries was prepared in the same manner as in Example 1, except that the embossing roll was thermally fused.

Comparative example  One

A fine glass fiber separator (AGM (Absorbed glass mat) of Amersil, Germany) having a weight of 100 g / m ² per unit area was used.

Comparative example  2

A condensed silica polyethylene separator product (PE Sepaper of Sebang Industries Co., Ltd.) having a weight of 100 g / m ² per unit area was used.

Tensile strength, tear strength, air permeability, heat resistance, pressurized retention rate, and liquid absorption rate of the separators for batteries according to Examples 1 to 4 and Comparative Examples 1 and 2 were measured. Specific measurement methods are as follows.

Tensile strength: KS K 0520 method was used.

Tear strength: KS K 0536 method was used.

Breathability: ASTM D 737 was used.

Hot air shrinkage (heat resistance): After shrinking a specimen of 25 cm × 25 cm in a hot air oven at 130 ° C. for 10 minutes, the shrinkage is measured. Hot air shrinkage is calculated by the following equation.

[Equation 1]

Hot air shrinkage (%) = (before treatment-after treatment) / before treatment × 100

Pressurized retention rate: Cut a 5 cm x 5 cm specimen and measure the initial mass (M0) at 60% relative humidity (RH) at room temperature. The measured specimen is immersed in an aqueous solution of 37% sulfuric acid for 1 hour. The immersed specimen is pressurized under 5 MPa for 20 seconds using a pressurized press and the mass (M1) of the specimen is measured.

Liquid Absorption Rate: After dipping 5 mm of the bottom of the specimen 2.5 cm wide x 20 cm in length perpendicular to 37% sulfuric acid solution, measure the height of the sulfuric acid solution raised through the specimen.

TABLE 1

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Weight (g / m ² ) 100 100 100 100 100 100 Aeration rate (ccs) 5.3 5.7 5.6 5.0 5.8 - Tensile Strength (kg / 5cm) MD CD 29 13 35 18 28 14 36 20 9 4 38 20 Tear strength (kg) MD CD 6 7 8 7 8 6 7 5 0.5 0.5 8 8 Liquid suction speed (mm / min) 98 99 96 94 99 76 Liquid retention rate (%) 328 332 330 315 317 250 Hot air shrinkage (%) 0.1 0.2 0.1 0.2 0.2 5.4

In the tensile and tear strengths of Table 1, MD (machine direction) means a direction parallel to the advancing direction of the spunbond nonwoven fabric manufacturing process, CD (cross direction) means a direction perpendicular to the MD.

As shown in Table 1, it can be seen that the spunbond nonwoven separator for batteries prepared according to Examples 1 to 4 of the present invention has excellent mechanical strength, liquid suction rate, and liquid retention rate, and low shrinkage rate due to hot air. .

Since the spunbonded nonwoven fabric separator for batteries of the present invention includes two or more kinds of polymer components, the advantages of each polymer component play a complementary role, and thus the mechanical strength of the spunbonded nonwoven fabric separator is superior to that of the conventional fine glass fiber separator or the separator using agglomerated silica and polyethylene. And excellent heat resistance, and microporous poles formed between filaments of fineness cause capillary action and have excellent wettability.

Claims (10)

Fine fineness filament having a fineness of 0.05 to 0.2 denier, divided from split filaments composed of two or more polymer components Spunbond nonwoven separator for batteries comprising a. The spunbonded nonwoven separator for batteries according to claim 1, wherein the split filaments are made of polyester as the first component and polyolefin as the second component. The spunbonded nonwoven separator of claim 2, wherein the weight ratio of the first component and the second component is 20:80 to 80:20. delete The spunbond nonwoven fabric of claim 1, wherein the spunbond nonwoven separator is hydrophilically treated with at least one compound selected from the group consisting of an aqueous acrylic compound, a urethane compound, a vinyl alcohol compound, and a vinyl acetate compound. Separator. The spunbond nonwoven separator for batteries according to claim 1, wherein the spunbond nonwoven separator is hydrophilic treated by a surfactant treatment or a plasma treatment. Preparing a spunbond nonwoven fabric using split filaments composed of two or more polymer components; And Separating the filament of the fineness from the split filament of the spunbond nonwoven fabric produced Method for producing a spunbond nonwoven fabric separator for batteries comprising a. The method of claim 7, wherein the separating the filaments of the fineness is water punching at a water pressure of 50 to 300 kg · f / cm ² . The method of manufacturing a spunbonded nonwoven separator for batteries according to claim 7, wherein the method for manufacturing a spunbonded nonwoven separator for batteries further comprises the step of thermal fusion bonding of the spunbonded nonwoven fabric having undergone the separation process. The method of manufacturing a spunbond nonwoven separator for batteries according to any one of claims 7 to 9, wherein the method for manufacturing a spunbond nonwoven fabric separator for batteries further comprises performing a hydrophilic treatment on the spunbond nonwoven fabric. .

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