KR102487740B1 - Paper for separator containingpolyphenylene sulfide microfiber - Google Patents

Abstract

In the present invention, an unstretched polyphenylene sulfide microfiber having a fiber length of 1 to 10 mm and a fineness of 0.1 to 0.5 denier and a stretched polyphenylene sulfide microfiber having a fiber length of 1 to 10 mm and a fineness of 0.01 to 0.1 denier have a weight ratio of 20: It is contained in a ratio of 80 to 60:40, and the unstretched polyphenylene sulfide microfibers and the stretched polyphenylene sulfide microfibers relate to paper for separators containing polyphenylene sulfide microfibers formed into island-in-the-sea microfibers.

Description

Paper for separation membrane containing polyphenylene sulfide microfiber {PAPER FOR SEPARATOR CONTAININGPOLYPHENYLENE SULFIDE MICROFIBER}

The present invention relates to a paper for a separator containing polyphenylene sulfide microfibers, and more particularly, to a paper for a separator containing polyphenylene sulfide microfibers formed by including unstretched polyphenylene sulfide microfibers and stretched polyphenylene sulfide microfibers. It's about restraint.

Polyphenylene sulfide fibers have a variety of markets, including not only the industrial fields of battery separators, dust collector filters, and interior materials for automobiles, but also the interior fields of wallpaper, curtains, sofas, and bedding, and the protective clothing fields of industrial protective clothing and protective gloves. In recent years, as the demand for chemical resistance and flame retardancy has increased, its use has been increasing.

In particular, it is a filter material used for filters in filter cloth dust collectors. It is generally made of polyphenylene sulfide fibers, unlike non-woven fabrics made of glass fiber (Glass), meta aramid (MA), teflon (PTFE), polyimide (PI), etc. The prepared non-woven fabric is attracting attention as a heat-resistant filter material due to excellent heat resistance, chemical resistance, low absorption characteristics, and shape stability of polyphenylene sulfide fibers.

In addition, the secondary battery is a chemical battery that can be used semi-permanently by continuously repeating charging and discharging using an electrochemical reaction.

The secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, and a separator. Among them, the required characteristic of the separator is the permeability of lithium ions based on high porosity while electrically insulating the positive electrode and the negative electrode by separating them. to increase the ionic conductivity.

Polyolefin-based polymer films such as polyethylene (PE) and polypropylene (PP), which are advantageous in forming pores and have excellent chemical resistance and mechanical properties, are widely used as polymer substrates for separators that are generally used. However, polyolefins heat shrink at high temperatures. This is severe, and physically weak.

Korean Patent Registration No. 1910222 is an invention related to a separator for secondary batteries for improving heat resistance, and a base layer containing a polyolefin-based resin, a first inorganic material layer containing a polymer resin and inorganic particles on both sides of the base layer, and a second inorganic material The layers are laminated, respectively, to increase heat resistance.

However, Korean Patent Registration No. 1910222 uses a conventional polyolefin-based resin having poor heat resistance, so there is a problem in that heat resistance is not significantly increased.

Efforts to overcome the various problems of the existing polyolefin-based separators have been actively conducted recently, such as co-extrusion, non-woven fabric and ceramic composite technologies, and surface modification of separators for the purpose of improving affinity with electrolyte. Technology development is in progress.

The present invention was invented to solve the problems of the prior art as described above, and includes polyphenylene sulfide microfibers having improved heat resistance by forming paper for separators with microfibers formed of polyphenylene sulfide resin having excellent heat resistance and chemical resistance. It is an object of the present invention to provide a paper for a separation membrane.

In addition, the polyphenylene sulfide microfiber is a sea-island type microfiber, and it is an object of the present invention to provide a paper for a separator including polyphenylene sulfide microfiber with improved physical properties due to excellent stretching processability and dry heat shrinkage.

In order to solve the above problems, the present invention provides unstretched polyphenylene sulfide microfibers with a fiber length of 1 to 10 mm and a fineness of 0.1 to 0.5 denier, and a stretched polyphenylene sulfide microfiber with a fiber length of 1 to 10 mm and a fineness of 0.01 to 0.1 denier. The phenylene sulfide microfibers are contained in a weight ratio of 20:80 to 60:40, and the unstretched polyphenylene sulfide microfibers and the stretched polyphenylene sulfide microfibers are formed into sea-island microfibers. Includes polyphenylene sulfide microfibers It provides a paper for a separator that does.

In addition, the sea-island type microfibers of the drawn polyphenylene sulfide microfibers include a spinning step of composite spinning with a sea component containing a soluble polyester resin and an island component containing polyphenylene sulfide resin; A cooling step of cooling the spun island-in-the-sea yarn; A first winding step of winding the cooled island-in-the-sea yarn to produce undrawn yarn; A drawing step of drawing the wound unstretched yarn using two or more rollers and the temperature of the last drawing roller is 160 to 250 ° C; A contraction step of contracting the drawn island-in-the-sea yarn at an overfeed rate of 0.8 to 0.99; and a second winding step of winding the shrunken island-in-the-sea yarn.

In addition, the temperature of the drawing roller at the end of the drawing step provides a paper for a separator containing polyphenylene sulfide microfibers, characterized in that 180 ~ 220 ℃.

In addition, in the shrinking step, the island-in-the-sea yarn is shrunk at an overfeed rate of 0.85 to 0.95 to provide a paper for a separator comprising polyphenylene sulfide microfibers.

In addition, the paper for the separator is provided with a paper for the separator containing polyphenylene sulfide microfibers, characterized in that produced by a wet papermaking method.

In addition, it provides a paper for a separator comprising polyphenylene sulfide microfibers, characterized in that the dry heat shrinkage rate of the island-in-the-sea yarn is 1 to 5% after the second winding step.

As described above, the paper for a separator comprising polyphenylene sulfide microfibers according to the present invention is formed of microfibers made of polyphenylene sulfide resin having excellent heat resistance and chemical resistance, thereby improving heat resistance.

In addition, the polyphenylene sulfide microfiber is a sea-island type microfiber, and when manufacturing the island-in-the-sea yarn, the temperature control and shrinkage step are performed in the drawing step to improve the drawing processability and dry heat shrinkage rate of the polyphenylene sulfide island-in-the-sea yarn, thereby improving the physical properties of paper for separation membranes. has the effect of

1 is a view showing a process chart of a method for manufacturing polyphenylene sulfide sea-island yarn according to the present invention.
2 is a view briefly showing a second step of the method for manufacturing polyphenylene sulfide island-in-the-sea yarn according to the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. First of all, it should be noted that in the drawings, the same components or parts are denoted by the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related known functions or configurations are omitted in order not to obscure the gist of the present invention.

As used herein, the terms 'about', 'substantially', and the like are used in a sense at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and are intended to convey an understanding of the present invention. Accurate or absolute figures are used to help prevent exploitation by unscrupulous infringers of the disclosed disclosure.

The 'island-type microfiber' of the present invention refers to a microfiber formed into a microfiber by dissolving a water-soluble resin through reduction processing after being manufactured as a sea-island yarn.

1 is a diagram showing a process diagram of a method for manufacturing polyphenylene sulfide island-in-the-sea yarn according to the present invention, and FIG. 2 is a diagram briefly showing a second step of the method for manufacturing polyphenylene sulfide island-in-the-sea yarn according to the present invention.

The present invention relates to a paper for a separator comprising polyphenylene sulfide microfibers formed by including unstretched polyphenylene sulfide microfibers and stretched polyphenylene sulfide microfibers.

The unstretched polyphenylene sulfide microfibers and the stretched polyphenylene sulfide microfibers used in the present invention are microfibers formed into sea-island type microfibers, and have excellent uniformity, so that homogeneous paper can be formed.

Preferably, the unstretched polyphenylene sulfide microfiber has a fiber length of 1 to 10 mm and a fineness of 0.1 to 0.5 denier, and the stretched polyphenylene sulfide microfiber has a fiber length of 1 to 10 mm and a fineness of 0.01 to 0.1 denier. would be preferable

The fiber length and fineness of the undrawn polyphenylene sulfide microfiber and the drawn polyphenylene sulfide microfiber may be adjusted according to the purpose of paper for a separator.

The unstretched polyphenylene sulfide microfiber is a configuration that serves as a binder when making paper, and if the content is too low or too high, the physical properties of paper may be deteriorated. Polyphenylene sulfide microfibers are preferably contained in a weight ratio of 20:80 to 60:40.

The unstretched polyphenylene sulfide microfibers and the stretched polyphenylene sulfide microfibers are manufactured into polyphenylene sulfide island-in-the-sea yarn composed of an island component containing a polyphenylene sulfide resin as a sea component containing a soluble polyester resin, and then It is a microfiber formed by dissolving polyester resin through reduction processing.

The polyphenylene sulfide resin forming the island component is a crystalline engineering plastic having a relative viscosity of 0.1 to 10 and has high heat resistance and excellent mechanical properties, chemical resistance, electrical properties, and dimensional stability. Examples of applications include electric/electronic parts, automobile parts, mechanical parts, and the like.

In addition, the polyphenylene sulfide (Polyphenylene sulfide) resin may be a linear, cross-linked, or semi-cross-linked polymer, but preferably a linear one, a weight average molecular weight (Mw) of 2,000 to 8,000, and a melt flow index of 20 to 8,000. 150g/10min can be used.

In addition, black coloring is required to use as an automobile interior material by using the mechanical and chemical durability, which are the above characteristics of Polyphenylene sulfide, and a dope-dyeing method in which a colorant is added in the pre-spinning process is used to improve color fastness. can be excellent. The dyeing process is preferably used when expressing basic colors such as black, indigo, and brown.

The sea component is formed of a soluble polyester resin, and the polyphenylene sulfide island-in-the-sea yarn of the present invention is formed into a polyphenylene sulfide microfiber by dissolving the soluble polyester resin through weight loss processing later.

The soluble polyester resin is currently used in many fields and is a polymer resin that can be used in various fields with the advantage of being easily dissolved in an alkaline solution. will be available

In particular, 0.1 to 1 mol% of dimethyl-5-sulfo isophthalate phosphonium salt (DMSP) or di(β-hydroxyethyl group)-sulfo isophthalate phosphatate with respect to terephthalic acid or its derivatives 90 to 95% by weight of a polyester resin containing phonium salt (Di(β-hydroxyethyl)-5-sulfo isophthalate phosphonium salt, DHSP) and 2 to 5 mol% of 5-sodium sulfoisophthalic acid (DMS) and water A water-soluble polyester resin containing 5 to 10% by weight of water-soluble polyalkylene oxide having an average molecular weight of 400 to 20,000 may be used.

The dimethyl-5-sulfo isophthalate phosphonium salt (DMSP) or di(β-hydroxyethyl group)-sulfo isophthalate phosphonium salt (DHSP)-containing polyester resin and polyalkylene oxide are formed of a soluble poly As the ester resin is used, the strength of the yarn produced can be increased, and the improvement in strength will increase the melt spinning property and reduce the thread breakage in yarn processing.

Using only dimethyl-5-sulfo isophthalate phosphonium salt (DMSP) or di(β-hydroxyethyl)-sulfo isophthalate phosphonium salt (DHSP) together with the 5-sodium sulfoisophthalic acid (DMS) It is possible to reduce the amount of dimethyl-5-sulfo isophthalate phosphonium salt (DMSP) or di(β-hydroxyethyl group)-sulfo isophthalate phosphonium salt (DHSP) compared to the case, and thus a cost reduction effect can be expected.

As described above, the polyphenylene sulfide island-in-the-sea yarn of the present invention formed of the island component and the sea component is preferably formed in an area ratio of 2:8 to 8:2, and when the sea component is dissolved, the polyphenylene of the island component It is preferable that the sulfide microfiber has a single yarn fineness of 1 denier or less.

As described above, the polyphenylene sulfide island-in-the-sea yarn according to the present invention, as shown in FIG. 1, includes the first process of producing undrawn yarn (POY) through a spinning step, a cooling step, and a first winding step, a drawing step, a shrinking step, and a second step. It will be possible to improve manufacturing processability and physical properties of polyphenylene sulfide sea-island yarn by manufacturing it in a two-step process of the second process of manufacturing undrawn yarn into drawn yarn (FDY) through the winding step.

That is, the undrawn polyphenylene sulfide microfiber of the present invention is manufactured by reducing the amount of undrawn yarn (POY) produced in the first step, and the drawn polyphenylene sulfide microfiber is manufactured by reducing the amount of drawn yarn (FDY) produced in the second step. It is manufactured by

The first process is a process of manufacturing unstretched yarn (POY) through a spinning step, a cooling step, and a first winding step. In the step of complex spinning powder in the form of island-in-the-sea yarn to make fibers, it will be possible to spin at a spinning temperature of about 270 ~ 350 ℃ using a general island-in-the-sea yarn composite spinning device.

The cooling step is a step of cooling the spun island-in-the-sea yarn, which sufficiently cools the island-in-the-sea yarn before winding so that the fibers do not adhere to each other in the winding process, and the cooling temperature is 20 It is preferably below °C, and more preferably 10 to 20 °C.

In the cooling step, if the cooling temperature is too low or exceeds 20 ° C, the crystallinity of the spun sea-island yarn may be lowered, resulting in deterioration in spinning processability and physical properties of the island-in-the-sea yarn.

The first winding step is a step of winding the cooled island-in-the-sea yarn, and it is preferable to manufacture unstretched yarn by winding the yarn at a winding speed of 1500 to 2500 m/min.

If the winding speed of the first winding step is too low, the elongation rate is too low, and a trimming phenomenon may occur in the subsequent second process, resulting in a decrease in fairness. If the winding speed is too fast, the elongation rate in the first process is too high and the cooling step The physical properties of the sea-island yarn may be deteriorated due to poor cooling.

The second process is a process of manufacturing undrawn yarn into drawn yarn (FDY) through a drawing step, a shrinking step, and a secondary winding step, and is performed through a plurality of rollers.

In the second process, for example, as shown in FIG. 2, the roller 100 on which unstretched yarn is wound, the stretching rollers 210 and 230 for stretching, the contraction roller 250 for contraction by giving an opioid, and the take-up roller 300 for winding can be carried out.

The drawing step is a step of drawing the wound unstretched yarn using two or more rollers, and it is preferable to draw at a speed of 300 to 500 m/min to suppress thread breakage during drawing.

In the drawing step, the processability of the island-in-the-sea yarn can be improved by controlling the drawing temperature.

That is, when manufacturing with the apparatus as shown in FIG. 2, the temperature of the first elongating roller 210 is 70 to 90 ° C, and the temperature of the last elongating roller 230 is preferably 160 to 250 ° C.

If the drawing temperature is too high when the unstretched yarn is started to be drawn, the crystallinity of the polyphenylene sulfide resin rapidly progresses and the orientation ratio is lowered during drawing, which may decrease the strength of the island-in-the-sea yarn. The last drawing roller 230, where the drawing starts and the drawing is finished, can maintain the increased strength by giving the sea-island yarn a heat treatment effect drawn at a high temperature of 160 to 250 ° C.

In the stretching step, the shrinkage rate of the polyphenylene sulfide island-in-the-sea yarn varies greatly depending on the temperature of the last stretching roller, and the last stretching roller 230 is at a temperature of 180 to 220 ° C. would be more preferable.

In the stretching step, the stretching ratio may be adjusted in consideration of the stretching rate in the first step, but if the stretching ratio is too large, the stretching processability may deteriorate, so it is preferable to stretch the film by about 1.5 to 4 times.

The shrinking step is a step of shrinking the drawn island-in-the-sea yarn at an overfeed rate of 0.7 to 0.99, and is a step performed between the last drawing roller and the next roller in the drawing step. That is, in FIG. 2, it is a step between the last elongation roller 230 and the shrinking roller 250.

The contraction step is a step performed continuously with the stretching step, and the shrinkage rate of the island-in-the-sea yarn can be lowered by causing the island-in-the-island yarn to shrink by relaxing the island-in-the-sea yarn in a high temperature state with an overfeed rate of 0.7 to 0.99 with the last stretching roller.

Through the shrinking step, it is preferable to shrink the island-in-the-sea yarn at an overfeed rate of 0.85 to 0.95 in the shrinking step for low dry heat shrinkage of the polyphenylene sulfide sea-island yarn of the present invention.

The second winding step is a winding step of winding the contracted polyphenylene sulfide sea-island yarn.

The polyphenylene sulfide island-in-the-sea yarn according to the present invention produced by the first process of spinning to produce undrawn yarn (POY) and the second process of manufacturing undrawn yarn into drawn yarn (FDY) cooling temperature in the cooling step By adjusting the drawing temperature in the control and drawing step, polyphenylene sulfide sea-island yarn has excellent physical properties due to high manufacturing processability and low dry heat shrinkage rate by adjusting the temperature of the drawing roller at the end of the drawing step and the overfeed rate in the shrinking step. can be manufactured

It is preferable that the polyphenylene sulfide sea-island yarn of the present invention has a dry heat shrinkage rate of 1 to 5% at 180 ° C.

The paper for a separator of the present invention is a polyphenylene sulfide microfiber formed by reducing the polyphenylene sulfide sea-island yarn produced in the first and second processes, and is an unstretched polyphenylene sulfide microfiber manufactured through the first process. And, a drawn polyphenylene sulfide microfiber produced through the first process and the second process may be used.

Paper for separators containing polyphenylene sulfide microfibers according to the present invention is obtained by removing the usable polyester resin by reducing the unstretched yarn (POY) produced in the first process and the drawn yarn (FDY) produced in the second process. It can be prepared into paper by a dry/wet papermaking method by mixing unstretched polyphenylene sulfide microfibers and drawn polyphenylene sulfide microfibers at a weight ratio of 20:80 to 60:40.

The paper for a separator of the present invention is preferably manufactured by a wet papermaking method, in which physical properties can be easily controlled. It may be prepared by dehydration through a nip roller and calendering at 220 to 280 ° C.

As described above, the paper for a separator of the present invention formed by including unstretched polyphenylene sulfide microfibers and stretched polyphenylene sulfide microfibers improves stability due to the high heat resistance of polyphenylene sulfide microfibers, thereby increasing the stability of high-output secondary batteries. You will be able to.

Hereinafter, the present invention will be explained through examples. The following examples are only for a more accurate understanding of the present invention, but do not limit the protection scope of the present invention.

◈ Measurement method

* Relative viscosity is determined by dissolving the sample in a solvent (mixture of phenol and tetrachloride ethane at a 5:5 weight ratio) at a concentration of 0.5% and using an Ubbelohde type viscous tube set in a thermostat adjusted to a constant temperature to determine the volume of the solution. Calculate the flow time (sec) of and find the relative viscosity by using the flow time (sec) of the same volume of solvent

* Stretching fairness: Grade 1 production / Total production * 100 = Yield (based on weight)

* Dry heat shrinkage rate: 180℃ shrinkage rate, length change rate (%) before and after 1 hour heat treatment

* Tensile strength: Measured using L&W's Tensile Tester according to the ASTM D828 measurement method

* Heat resistance: 160, 180℃ shrinkage rate, length change rate (%) before and after 1 hour heat treatment

* Flame retardancy: French flame retardant test standard NFP 92-503, 504, 505 evaluation

* Film thickness: measured using Mitutoyo's thickness meter in the KSKISO9073-2 measurement method

◎ Preparation Example 1: Dry heat shrinkage rate according to the temperature of the stretching roller

Using a water-soluble polyester resin copolymerized with 2% by weight of polyethylene glycol having a molecular weight of 20,000 as the sea component and a polyphenylene sulfide resin having a relative viscosity of 0.3 as the island component, the area ratio of sea-island islands in each melting extruder is 3:7, The island component was supplied to a spinneret for sea-island composite spinning with 37 spinnerets, composite spinning was performed at 290 ° C, cooled to 15 ° C, and undrawn yarn was first wound at a speed of 2,000 m / min.

The prepared unstretched yarn was drawn at a draw ratio of 2 times using the same apparatus as in FIG. 2, a contraction step was performed at an overfeed ratio of 0.90, and a second winding was performed to prepare polyphenylene sulfide island-in-the-sea yarn.

In the drawing step, the temperature of the first drawing roller was 80 ° C and the temperature of the last drawing roller (second drawing roller) was adjusted to 140 ~ 260 ° C, and the dry heat shrinkage by temperature was measured and shown in Table 1.

2nd roller temperature (℃) 140 160 180 200 220 240 260 Dry heat shrinkage (%) 9.1 6.8 4.6 2.89 2.1 1.92 1.9 Stretching fairness (%) 96 95.4 95 91.5 90 81 54

As shown in Table 1, when the overfeed ratio is fixed at 0.90, when the temperature of the last drawing roller rises, the dry heat shrinkage rate of the island-in-the-sea yarn tends to decrease, and when the temperature of the last drawing roller rises, the drawing fairness tends to decrease. Able to know.

When the temperature of the last stretching roller is 180 to 220 ° C., the dry heat shrinkage rate is 5% or less, and the stretching processability is 90% or more, indicating that both the dry heat shrinkage rate and the stretching processability are excellent.

◎ Preparation Example 2: Dry heat shrinkage rate according to Obifeed rate

Polyphenylene sulfide island-in-the-sea yarn was prepared as in Preparation Example 1, but in the drawing step, the temperature of the first drawing roller was 80 ° C and the temperature of the last drawing roller (second drawing roller) was drawn at 200 ° C, and in the shrinking step, the temperature was exceeded. By adjusting the feed rate to 0.75 to 1.0, the dry heat shrinkage rate for each overfeed rate was measured and shown in Table 2.

overfeed rate 0.75 0.8 0.85 0.9 0.95 One Dry heat shrinkage (%) 1.62 1.85 2.02 2.89 4.23 9.32 Stretching fairness (%) 32 71 86 91 95 95

As shown in Table 2, when the temperature of the last stretching roller is fixed at 200 ° C., it can be seen that the higher the overfeed rate, the lower the dry heat shrinkage rate, and the lower the overfeed rate, the lower the stretching processability.

When the overfeed ratio is 0.85 to 0.95, the dry heat shrinkage rate is 5% or less, and the stretching processability is 85% or more, which indicates that both the dry heat shrinkage rate and the stretching processability are excellent.

◎ Preparation Examples 1 to 3, and Comparative Examples 1 to 3

Polyphenylene sulfide island-in-the-sea yarn was prepared as in Preparation Example 1, but in the drawing step, the temperature of the first drawing roller was 80 ° C and the temperature of the last drawing roller (second drawing roller) was adjusted to 140 ~ 240 ° C. In the contraction step, the overfeed rate was adjusted to 0.75 to 1.0 to prepare polyphenylene sulfide island-in-the-sea yarn.

Table 3 shows the overfeed rate, the temperature and stretching processability of the last stretching roller, and the dry heat shrinkage of each manufacturing example and manufacturing comparative example.

division Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Comparative Example 1 Manufacturing Comparative Example 2 Manufacturing Comparative Example 3 overfeed rate 0.95 0.8 0.9 0.75 One 0.9 2nd roller temperature (℃) 200 200 240 200 200 140 Stretching fairness (%) 95 86 81 24 95 96 Dry heat shrinkage (%) 4.23 2.02 1.92 1.62 9.32 9.10

As shown in Table 3, Manufacturing Examples 1 to 3 are superior in stretching processability and dry heat shrinkage to those of Manufacturing Comparative Examples 1 to 3, the overfeed ratio is 0.8 to 0.99, and the temperature of the final drawing roller is in the range of 160 to 250 ° C. Manufacturing Examples 1 to 3 had a stretching processability of 80% or more and a dry heat shrinkage rate of 5% or less, indicating that all of them had excellent manufacturing processability and physical properties.

◎ Examples 1 to 3 and Comparative Example 1

The unstretched polyphenylene sulfide microfiber with a fiber length of about 3 mm obtained by reducing the undrawn yarn of Preparation Example 1 and the drawn polyphenylene sulfide microfiber with a fiber length of about 3 mm obtained by reducing the drawn yarn of Production Example 2 were prepared at a constant rate. It was mixed in a ratio and uniformly dispersed to make a slurry, and a web was formed by a wet papermaking method, dehydrated through a nip roller, and calendered at 260 ° C. Separator containing polyphenylene sulfide microfibers according to the present invention Paper was prepared.

Table 4 shows the fineness and mixing ratio of the unstretched polyphenylene sulfide microfiber and the drawn polyphenylene sulfide microfiber according to each Example and Comparative Example.

◎ Comparative Example 2

Unstretched polyphenylene sulfide fibers with a fiber length of about 3 mm and stretched polyphenylene sulfide fibers with a fiber length of about 3 mm were mixed in a certain ratio and uniformly dispersed to form a slurry, and a web was formed by a wet papermaking method, and a nip roller (Nip Roller) and dehydrated, and calendered at 260 ° C. to prepare paper for separators containing polypropylene microfibers.

Table 4 shows the fineness and mixing ratio of the unstretched polyphenylene sulfide fiber and the drawn polyphenylene sulfide fiber of Comparative Example 2.

◎ Comparative Example 3

Unstretched polypropylene microfibers with a fiber length of about 3 mm and stretched polypropylene microfibers with a fiber length of about 3 mm were mixed in a certain ratio and uniformly dispersed to form a slurry, and a web was formed by a wet papermaking method, and a nip roller After dehydration, and calendering at 120 ° C., paper for a separator containing polypropylene microfibers was prepared.

Table 4 shows the fineness and mixing ratio of the unstretched polypropylene microfiber and the drawn polypropylene microfiber of Comparative Example 3.

The tensile strength, shrinkage, flame retardancy, and film thickness of the separator papers of Examples 1 to 3 and Comparative Examples 1 to 3 prepared above were measured and shown in Table 4.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Polymer
PPS PPS PPS PPS PPS PP Fineness (D) stretched yarn 0.023 0.023 0.1 0.023 One 0.023 Miyeon Shrine 0.1 0.1 0.2 0.1 One 0.1 mixing ratio
(weight%) stretched yarn 60 80 60 95 60 60 Miyeon Shrine 40 20 40 5 40 40 The tensile strength (N/cm2) 37.5 29.3 43.4 13.2 50.1 40.4 by temperature
heat resistance
(shrinkage rate) 160℃ shrinkage rate 0 0 0 0 0 melting 180℃ shrinkage 2 1.5 1.8 2.1 2.8 melting flame retardant - Pass (M1) Pass (M1) Pass (M1) Pass (M1) Pass (M1) Pass (M2) film thickness μm 17 14 20 15 51 25

As shown in Table 4, it can be seen that the paper for separators of Examples 1 to 3 formed of the polyphenylene sulfide microfiber according to the present invention has excellent tensile strength, heat resistance, and flame retardancy, and has a good film thickness of 20 μm or less.

In Comparative Example 1, it can be seen that the content of unstretched polyphenylene sulfide microfibers is low, and the tensile strength is low due to the lack of components that can serve as a binder. Comparative Example 2 is made of general polyphenylene sulfide fibers, not microfibers. It can be seen that the film thickness is greatly increased as a paper for a separator, which is not suitable as a paper for a separator. In Comparative Example 3, when formed into a paper for a separator with ultra-fine polypropylene, it melts at high temperature and has no heat resistance, and has flame retardancy. It can be seen that the lower

Claims (6)

The weight ratio of unstretched polyphenylene sulfide microfiber with a fiber length of 1 to 10 mm and a fineness of 0.1 to 0.5 denier and drawn polyphenylene sulfide microfiber with a fiber length of 1 to 10 mm and a fineness of 0.01 to 0.1 denier is 20:80 to 60. : 40,
The unstretched polyphenylene sulfide microfibers and the stretched polyphenylene sulfide microfibers are formed as sea-island microfibers,
The sea-island microfibers of the stretched polyphenylene sulfide microfibers,
A spinning step of composite spinning with a sea component containing a soluble polyester resin and an island component containing a polyphenylene sulfide resin;
A cooling step of cooling the spun island-in-the-sea yarn;
A first winding step of winding the cooled island-in-the-sea yarn to produce undrawn yarn;
A drawing step of drawing the wound unstretched yarn using two or more rollers and the temperature of the last drawing roller is 180 to 220 ° C;
A shrinking step of shrinking the drawn island-in-the-sea yarn at an overfeed rate of 0.85 to 0.95; and,
A paper for a separation membrane comprising polyphenylene sulfide microfibers, characterized in that it comprises a secondary winding step of winding the shrunken island-in-the-sea yarn. delete delete delete According to claim 1,
The paper for the separation membrane comprising polyphenylene sulfide microfibers, characterized in that the paper for the separation membrane is produced by a wet papermaking method. According to claim 1,
Paper for separators containing polyphenylene sulfide microfibers, characterized in that the dry heat shrinkage of the island-in-the-sea yarn is 1 to 5% after the second winding step.

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