JP6550655B2 - Polyphthalamide meltblown nonwoven fabric, method for producing the same, and separator for heat-resistant battery - Google Patents

Description

  The present invention relates to a meltblown nonwoven fabric made of polyphthalamide (hereinafter sometimes referred to as "PPA"), a method for producing the meltblown nonwoven fabric and a separator for a heat resistant battery, and more particularly, a liquid filter And a melt-blown nonwoven fabric that can be used as a separation membrane for an air filter, etc., and in particular, can be provided as a battery separator excellent in heat resistance and shrinkage resistance, and further in electrolyte retention and liquid absorption speed It is.

  In recent years, non-woven fabrics have been used for a wide variety of applications, and their applications have been further expanded significantly. In the past, it has been widely used for various separation membranes such as liquid filters and air filters, taking advantage of its characteristics, but after that, base fabrics for sanitary materials such as paper diapers and sanitary products, heat insulation materials, materials for clothing, medical materials, etc. Also, with the development of batteries, they are also used for electrochemical substrates (sometimes referred to as “battery” hereinafter) such as primary batteries, secondary batteries, electrolytic capacitors, and electric double capacitors. It has been used as a separator that is a component. In particular, lithium batteries are frequently used as separators that are insoluble in organic solvents and are stable for electrolytes and electrode active materials.

  A separator as a component of a battery is required to have functions such as separation between a positive electrode material and a negative electrode material, prevention of short circuit, passage of electrolyte or ion, absorption of electrolytic solution and maintenance of close contact between electrolyte solution and electrode. It has been.

However, when a short circuit occurs inside and outside the battery, a large current is discharged, which causes Joule heat or chemical reaction heat to cause thermal contraction of the separator between the positive and negative electrodes facing each other, or the separator heat melts. As a result, the short circuit between the positive and negative electrodes results in a direct short circuit, resulting in the expansion of the internal short circuit and the discharge of a large amount of heat to the surroundings, resulting in the discharge of a large amount of gas. Conventional separators made of polyolefin nonwoven fabrics such as polyethylene and polypropylene have a melting point of polyethylene of about 125 to 140 ° C and a melting point of polypropylene of about 160 to 180 ° C. There was a problem that short circuiting due to dissolution of the separator was likely to occur. In order to solve such a problem, a shutdown function that is a function of blocking current by blocking the passage of ions,
It has been desired that the separator itself has a function of not shrinking or melting.

Melt blown nonwoven fabrics using heat-resistant resins have been developed as battery separators that solve these problems. For example, Japanese Patent Application Laid-Open No. 2004-47280 (hereinafter referred to as “Patent Document 1”) describes a melt blown nonwoven fabric separator using polyphenylene sulfide (PPS) having a melting point of about 280 ° C., which is a heat resistant resin, as a raw material resin. . Japanese Patent Application Publication No. 2011-503880 (hereinafter referred to as “Patent Document 2”) describes a separator including a porous layer of polyamide nanofibers as a component of a capacitor.

  However, the battery separator using the heat-resistant resin, which has been proposed conventionally, has the disadvantage that the thermal contraction rate is still large, and the absorption of the electrolyte is insufficient even if the thermal contraction rate is low. There is a problem that the battery productivity is not good. In addition, the nano fiber having a thin fiber diameter shown in Patent Document 2 has a problem that the strength as a battery separator is insufficient, and safety and battery productivity are not sufficient.

  Under such circumstances, development of a melt-blown nonwoven fabric capable of providing a battery separator having a low thermal contraction rate and a high liquid absorption speed of the electrolyte has been desired.

JP 2004-47280 A Special table 2011-503880 gazette

  Therefore, the first object of the present invention is as a battery separator which is excellent in balance of tensile strength, air permeability and thermal contraction rate, excellent in heat resistance, low in thermal contraction rate, and fast in liquid absorption speed. A melt-blown nonwoven fabric that can be provided, a method for producing the melt-blown nonwoven fabric, and a battery separator comprising the melt-blown nonwoven fabric and having excellent heat resistance.

  A second object of the present invention is to provide a melt-blown nonwoven fabric with a small impact on the environment and a battery separator using the melt-blown nonwoven fabric.

  Then, the inventors of the present invention conducted intensive studies to solve the above-mentioned problems of the present invention, and as a result, identified that the raw material resin for manufacturing the nonwoven fabric is a key factor, and used polyphthalamide resin as the raw material resin. By using it, it is possible to realize a heat-resistant melt-blown non-woven fabric, and by focusing on the fact that the above-mentioned problems can be solved, the present invention has been conceived based on such findings.

  Also, by focusing on polyphthalamide resin with a high degree of biomass derived from plants and using it as a raw material resin, it is possible to maintain non-woven fabrics with the same degree of performance as conventional non-woven fabrics made of petroleum plastic, In the present invention, it was possible to obtain the finding that a non-woven fabric having properties stable in performance even in a high temperature use environment can be obtained, and the present invention was achieved based on such finding.

 Thus, according to the first invention of the present invention, there is provided a melt blown nonwoven fabric made of polyphthalamide resin.

  Further, according to a second aspect of the present invention, in the first aspect, the polyphthalamide resin has a melt flow rate measured at a load of 5.0 kg and a temperature of 300 ° C. in accordance with JIS K 7210. There is provided a melt blown nonwoven fabric having a content of 10 to 1000 g / 10 minutes and a terephthalamide unit content of 50 mol% or more.

Further, according to the third invention of the present invention, in the first or second invention, the average fiber diameter is 1 to 30 μm, the fabric weight is 5 to 300 g / m ² , and the air permeability is 0.1 to 200 cc / cm ^2. / Sec, a thickness of 10 to 1000 μm, a tensile strength of 1 to 50 N / 25 mm width, and a melt blown nonwoven fabric having a tensile elongation of 1 to 100% are provided.

  Further, according to the fourth invention of the present invention, in any of the first to third inventions, the thermal contraction rate, the tensile strength, the tensile elongation, and the electrolyte absorption speed are further improved by the press forming process. A melt-blown nonwoven fabric that can be provided as a battery separator is provided.

  Further, according to a fifth aspect of the present invention, in the fourth aspect, the thermal shrinkage is 1.5% or less in either of the lateral direction and the longitudinal direction after the heat treatment at 200 ° C. And the melt blown nonwoven fabric whose liquid absorption rate of the said electrolyte solution propylene carbonate is 310 seconds or less is provided.

  Further, according to a sixth aspect of the present invention, there is provided the melt-blown nonwoven fabric according to the fourth aspect, wherein the press forming process is a calendering process at a temperature above the glass transition temperature and below the melting point. .

  Further, according to the seventh invention according to the present invention, in the sixth invention, the calendering process is a means for sandwiching and pressing the melt-blown nonwoven fabric between calender rolls having two pairs of roll materials. There is provided a melt blown nonwoven fabric in which a roll material is metal / metal or metal / elastic body.

  Further, according to the eighth aspect of the present invention, after melting the polyphthalamide resin at an extruder temperature of 260 to 380 ° C., it is fed into a die set to 300 to 380 ° C. and discharged from the die nozzle at the same time. There is provided a method for producing a melt-blown nonwoven fabric comprising drawing by means of a high-temperature air-blowing gas at 260 to 380 ° C. to form fine fibers, and collecting the fine fibers in a collector placed at a position distant from the nozzles.

According to the ninth aspect of the present invention, after the polyphthalamide resin is melted at an extruder temperature of 260 to 380 ° C., it is fed into a die set at 300 to 380 ° C. and discharged from the die nozzle. Stretched with a high-temperature air blow gas of 260 to 380 ° C. to form fine fibers, collected in a collector installed at a position away from the nozzle, and the obtained melt blown nonwoven fabric is at a temperature not lower than the glass transition temperature and not higher than the melting point. There is provided a method of making a meltblown nonwoven comprising subjecting to a calendering process.
A method is provided.

  Further, according to a tenth aspect of the present invention, in the eighth or ninth aspect, the die has a nozzle hole diameter of 0.1 to 1 mm and a number of nozzles of 5 to 15 / cm, and the nozzle A method for producing a melt blown nonwoven fabric in which the amount of the polyphthalamide resin discharged from is 0.05 to 3 g / min / hole is provided.

  Moreover, according to the eleventh aspect of the present invention, there is provided a battery separator comprising the melt blown nonwoven fabric according to any one of the first to seventh aspects.

According to the present invention, by using a polyphthalamide resin as a raw material resin for producing a meltblown nonwoven fabric, it is possible to obtain a meltblown nonwoven fabric having specific heat resistance and excellent air permeability, and having a glass transition temperature or higher. By subjecting it to a pressure molding treatment at a temperature, a melt blown nonwoven fabric having a low thermal shrinkage rate and a high electrolyte solution absorption rate can be provided, and can be suitably used as a separator for heat-resistant batteries. Such heat-resistant separators can prevent explosive runaway such as melt rupture (meltdown) during heat generation such as short circuit, and are excellent in safety, and used as separators for high energy density batteries can do. In addition, by using a plant-derived polyphthalamide resin having a high degree of biomass as a raw material resin, the environmental load is lower than that of a petroleum-derived raw material, and harmful gases and the like are not generated at the time of combustion. It produces remarkable effects.

According to the present invention, as described above, it is a meltblown nonwoven fabric comprising polyphthalamide resin, having an average fiber diameter of 1 to 30 μm, a basis weight of 5 to 300 g / m ² , and an air permeability of 0.1 to 200 cc / m ^2. / Sec, thickness is 10 to 1000 μm, tensile strength is 1 to 50 N / 25 mm width, tensile elongation is 1 to 100%, and thermal contraction rate at a temperature of 200 ° C. is 5 in either the longitudinal direction or the transverse direction %, And a melt blown nonwoven fabric having physical properties of an electrolyte solution propylene carbonate absorption rate of 10 seconds or less is provided, and by press molding treatment, tensile strength, air permeability, heat shrinkage rate and electrolyte solution absorption rate are provided. A melt blown nonwoven fabric is provided which is further improved.

  Further, according to the present invention, after the polyphthalamide resin is melted by the extruder at 260 to 380 ° C., it is fed into a die set to 300 to 380 ° C. and discharged from the die nozzle, and at the same time the high temperature air blow at 260 to 380 ° C. A method for producing a meltblown nonwoven fabric is provided, which comprises drawing by means of gas into fine fibers and collecting it in a collector located at a distance from the nozzles.

  Furthermore, according to the present invention, the polyphthalamide resin is melted by an extruder at 260 to 380 ° C., and then fed into a die set to 300 to 380 ° C. and discharged from the die nozzle at the same time as high temperature air blow at 260 to 380 ° C. A method for producing a melt-blown nonwoven fabric comprising drawing by means of gas into fine fibers and collecting in a collector located at a distance from the nozzles and subjecting the obtained melt-blown nonwoven fabric to calendering at a temperature above the glass transition temperature. Is provided.

  The melt-blown nonwoven fabric according to the present invention can be used in various applications. Specifically, liquid filters made of the melt blown nonwoven fabric, for example, industrial filters, beverage filters, and fuel filters are provided. Further, as the air filter, for example, a medium performance filter, an air purifier filter, an automobile cabin filter, and the like are provided. Additionally, medical and hygiene materials such as masks can be provided. In particular, according to the present invention, there is provided a battery separator having excellent heat resistance made of a melt blown nonwoven fabric that has undergone the calendar processing.

Hereinafter, the present invention will be described in detail.
1. Polyphthalamide resin
The polyphthalamide resin used as the raw material resin for producing the melt blown nonwoven fabric according to the present invention preferably has a melt flow rate of 10 to 1000 g / 10 min measured at a load of 5.0 kg and 300 ° C. in accordance with JISK7210. . Moreover, as melt viscosity, what is 100-1000 Pa.s is preferable. Such polyphthalamide resins have terephthalamide units represented by the following structural formula:
(I)

Is preferably contained in an amount of 50 mol% or more from the viewpoint of controlling the melting point. In formula (i), R is a linear or branched aliphatic hydrocarbon group having 1 to 14 carbon atoms, and includes a substituted or unsubstituted aliphatic group. Specific examples of the aliphatic hydrocarbon group, tetramethylene, hexamethylene, dodecamethylene, and the like, and their alkyl-substituted analogs such as 2-methyl pentamethylene, 2, 4-dimethyl hexamethylene, 2, 2, 4-trimethyl Hexamethylene etc. are mentioned. A particularly preferred aliphatic hydrocarbon group is a hexamethylene group. In addition to the terephthalamide unit represented by the formula (i), the polyphthalamide resin also contains an isophthalamide unit represented by the following formula (ii).

(Ii)

Such polyphthalamide resins contain terephthalamide units (i), isophthalamide units (ii) and the like, for example, hexamethylene terephthalamide-isophthalamide-adipamide terpolymer (molar ratio 65; 25; 10) can be illustrated. Rilsan (registered trademark) HT manufactured by Arkema Co., Ltd. can be obtained as a commercial product, and has a melting point of 255 to 260 ° C. (according to DSC) and a glass transition temperature (Tg) of 90 ° C. (according to DSC). In addition, Amodel polyphthalamide manufactured by Amoco Chemical Co., Ltd. can also be obtained.

2. Polyphthalamide resin melt blown nonwoven fabric The polyphthalamide resin nonwoven fabric according to the present invention is a melt blown nonwoven fabric produced by a melt blow method.

  As a melt-blowing method, molten polyphthalamide resin was discharged as a molten polymer from a plurality of nozzle holes arranged in a row, and high-speed high-speed air was jetted and discharged from a jet gas port installed adjacent to an orifice die. Although the method of making the molten polymer into fine fibers and collecting the fiber stream is adopted, polyphthalamide as the raw material resin has a high melting point and is close to the decomposition temperature, so the manufacturing conditions need to be controlled. Yes, the following method is adopted.

  After the polyphthalamide resin is melted at an extruder temperature of 260 to 380 ° C, it is fed into a die set at 300 to 380 ° C and discharged from the die nozzle, and at the same time, drawn by a high temperature air blow gas of 260 to 380 ° C The meltblown nonwoven fabric obtained by collecting in a collector placed at a position distant from the fiberizing nozzle and further preferably, is subjected to calendering at a temperature above the glass transition temperature.

  In the melt blow device die, the nozzle hole is preferably 0.1 to 1 mmφ, and more preferably 0.2 to 0.8 mmφ. The number of nozzles is preferably 5 to 20 / cm, and more preferably 10 to 15 / cm. When the nozzle hole diameter is less than 0.1 mmφ, the discharge resin pressure is increased. On the other hand, when the nozzle hole diameter exceeds 1 mmφ, the fibers cannot be thinned. When the number of nozzles is less than 5 / cm, the discharge pressure of the polyphthalamide resin is high, while when the number of nozzles is more than 20 / cm, the fibers are fused too much, and uniformity of the non-woven fabric is increased. You will lose.

Moreover, as manufacturing conditions of the melt-blowing method, in the production of melt-blown nonwoven fabric using PPA resin as a raw material, the extrusion temperature is 260 to 380 ° C, preferably 300 to 350 ° C, and the die temperature is 300 to 380 ° C, Preferably it is 320-350 degreeC, Furthermore, high-speed air temperature is 260-380 degreeC, Preferably it is 300-350 degreeC. When the extruder / die and the air temperature are below the above ranges, the discharge resin pressure becomes high and fine fibers cannot be obtained.
On the other hand, when the above range is exceeded, gelation of the resin is promoted and deteriorates. Moreover, not only does the conveyor net be damaged, but the peelability of the resulting nonwoven fabric from the conveyor net is poor, making it difficult to produce stably.

The resin discharge amount is 0.05 to 3 g / min / hole, preferably 0.1 to 1 g / min / hole. When the resin discharge amount is small, the discharge resin pressure falls below the above range and a uniform non-woven fabric can not be obtained . On the other hand, when the resin discharge amount exceeds the above range, the discharge resin pressure becomes high and thin fibers are not obtained.

  Moreover, it is preferable that the melt blown nonwoven fabric which consists of polyphthalamide resin which concerns on this invention has the following physical property.

(1) Average fiber diameter The average fiber diameter of the melt blown nonwoven fabric made of the polyphthalamide resin according to the present invention is 1 to 30 µm, preferably 1.5 to 20 µm, and more preferably 2 to 8 µm. When the average fiber diameter is less than 1 μm, not only the strength is weakened, but also the internal resistance of the battery is too large when it is used for a battery separator. On the other hand, when the average fiber diameter exceeds 30 μm, the risk of internal short circuit increases when used in a battery separator.

(2) Basis weight The basis weight of the meltblown nonwoven fabric comprising the polyphthalamide resin according to the present invention is 5 to 300 g / m ² , preferably 7 to 80 g / m ² , and more preferably 10 to 50 g / m ² . When the basis weight is less than 5 g / m ² , the strength is insufficient, the reliability in the assembly is lowered, and when used for a battery separator, a short circuit is likely to occur, which is not preferable. On the other hand, when the weight per unit area exceeds 300 g / m ² , fluffing tends to occur at the time of nonwoven fabric production, and stable production becomes difficult. In addition, when used as a battery separator, the internal resistance may be increased.

(3) Air Permeability The air permeability of the meltblown non-woven fabric comprising the polyphthalamide resin according to the present invention is 0.1 to 200 cc / cm ² / sec, preferably 0.3 to 150 cc / cm ² / sec, and calendered More preferably, it is 1-50 cc / cm < ² > / sec by a process. When the air permeability is less than 0.1 cc / cm ² / sec, when used as a battery separator, the internal resistance is large, while when it exceeds 200 cc / cm ² / sec, when used as a battery separator, the inside The risk of shorting is increased.

(4) Thickness The thickness of the meltblown nonwoven fabric made of the polyphthalamide resin according to the present invention is 1-1000 μm, preferably 5-150 μm, more preferably 10-40 μm. When the thickness is less than 1 μm, the risk of an internal short circuit increases when used for a battery separator, while when it exceeds 500 μm, the battery capacity may decrease.

(5) Tensile strength The tensile strength of the melt-blown nonwoven fabric comprising the polyphthalamide resin according to the present invention is 2 to 50 N / 25 mm wide, preferably 10 to 40 N / 25 mm wide. If the tensile strength is less than 2 N / 25 mm width, breakage is likely to occur during assembly. On the other hand, when the tensile strength exceeds 50 N / 25 mm width, the elongation decreases extremely, and a defect is apt to occur due to a decrease in the degree of freedom when assembling.

(6) Tensile elongation The tensile elongation of the melt-blown nonwoven fabric comprising the polyphthalamide resin according to the present invention is 1 to 100%, preferably 5 to 80%, and more preferably 10 to 10 by calendering. 50%. If the tensile elongation is less than 1%, breakage tends to occur during assembly. On the other hand, if the tensile elongation is 100% or more, necking is likely to occur and it becomes difficult to stably assemble.

(7) Thermal shrinkage The thermal shrinkage at 150 ° C. of the meltblown nonwoven fabric comprising the polyphthalamide resin according to the present invention is preferably at most 3%, preferably at least 1%, in at least one of the transverse and longitudinal directions. The following content is more preferably 0.5% or less.
The thermal shrinkage at 200 ° C. is preferably 1.5% or less, preferably 1.0% or less, more preferably 0.5% or less in at least one of the horizontal direction and the vertical direction in both directions.
The melt blown nonwoven fabric made of the polyphthalamide resin according to the present invention preferably satisfies the heat shrinkage rate after heat treatment at both 150 ° C. and 200 ° C.

(8) Electrolyte absorption speed
The electrolyte solution absorption speed of the meltblown nonwoven fabric comprising the polyphthalamide resin according to the present invention is 10 seconds or less, preferably 3 seconds or less, and more preferably 1 second or less. When the electrolyte solution absorption speed of the separator is high, the production efficiency at the time of battery production becomes good.

(9) Evaluation of physical properties after heating test If the temperature inside the battery suddenly rises due to any cause, the separator may be deteriorated, and even if the temperature inside the battery is lowered thereafter, there is a fear of short circuit again. Therefore, it is preferable to keep the physical properties after heating at 200 ° C. for a certain period of 80% or more before heating.

3. Calendering of Meltblown Nonwoven Fabric In the present invention, it is preferable to perform calendering as a press forming treatment of a meltblown nonwoven made of a polyphthalamide resin obtained by the meltblowing method described above.

  The battery separator according to the present invention can be heat-shrinkable and electrolyte-absorbent by using a melt-blown non-woven fabric of polyphthalamide obtained by the above-described melt-blown method (hereinafter, also referred to as a calendered product) calendered. There is an effect that breakage resistance and the like are imparted by improving speed and tensile strength. In particular, a battery separator having excellent heat resistance, shrinkage resistance, and electrolyte solution absorption speed can be obtained by calendering treatment.

  The apparatus used for the method of calendering a melt-blown nonwoven fabric according to the present invention is a combination of 2 to 4 pairs of heat rolls, in particular 2 pairs of heat rolls, preferably an upright two-pair type, but a calender type Is not limited. The temperature and pressure of the calendering process are adjusted according to the temperature of the heat roll and the sense of mutual arrangement of the heat roll.

  As a calendering process of the melt-blown nonwoven fabric according to the present invention, after forming the melt-blown nonwoven fabric, the heating temperature is usually a temperature higher than the glass transition temperature, for example, 100 to 250 ° C., preferably 120 to 200 ° C. As a specific method, there is a method in which a melt-blown nonwoven fabric is processed by pressurizing between two pairs of rolls heated to a predetermined temperature.

  Although such a roll may be used that has two pairs of metal surfaces, the contact surface of one pair of rolls may be an elastic body such as a resin roll, and a combination of a roll having a metal surface may be used. When the contact surface of the two pairs of rolls is a metal surface, the uniformity of thickness can be mentioned as an effect, but when processing to a certain thinness, film formation occurs on the substrate surface and the variation in physical properties is large And the appearance is also non-uniform. On the other hand, when the contact surface of the roll is an elastic body, it is possible to obtain a battery separator having a low resistance and a uniform thickness both in terms of physical properties and appearance. A preferable thickness for the thin film separator is 10 to 40 μm, and more preferably 15 to 35 μm.

[Processing with elastic rolls]
As a heat-resistant separator, a battery separator made of a melt blown nonwoven fabric made of PPS resin has been proposed. However, since the elongation after crystallization of PPS resin is remarkably reduced, processing with a roll contact surface made of an elastic body. In the prior art, it has been difficult to obtain a thin battery separator having heat resistance and a thin film. This time, by using PPA resin, the melt-blown nonwoven fabric has excellent strength even when it is thinned, has a low thermal shrinkage rate, has a high rate of liquid absorption, and has little deterioration in physical properties in a high-temperature environment. In order to maintain a sufficient mechanical strength, attention was paid to the fact that it can be suitably used as a heat-resistant battery separator.

4. Battery separator Since the melt-blown nonwoven fabric made of the polyphthalamide resin according to the present invention is heat resistant, it can be suitably used for a battery separator that requires heat resistance. In particular, the calendered product has high tensile strength and low thermal shrinkage, so it has excellent safety to prevent explosive thermal runaway such as melt rupture (meltdown), and as a battery separator that requires heat resistance, preferable.

  As a battery separator, thickness is 10-40 micrometers, Preferably it is 15-35 micrometers, More preferably, it is 20-30 micrometers. Further, the heat shrinkage rate at 150 ° C. is preferably 1.5% or less, preferably 1% or less, more preferably 0.5% or less in both the horizontal direction and the vertical direction.

[Advantages of PPA resin in battery separator applications]
As shown in the examples described later, melt-blown nonwoven fabrics made of nylon as a raw material resin have suitable heat resistance and hydrophilicity, and are decomposed in a long-term alkaline solution, contrary to the battery characteristics obtained, and are liquid-retentive Battery life is short due to the occurrence of a drop or short circuit. As an alternative to this, PP non-woven fabric is also used with excellent chemical resistance and oxidation resistance, but since PP is hydrophobic, it needs to be subjected to a hydrophilization treatment and requires secondary processing. In contrast, melt blown non-woven fabrics made from PPA resin have long-term chemical resistance and wettability with electrolytes, and can be used as separators for long-life batteries that do not require secondary processing. I can expect it.

  In addition, according to the purpose of the melt-blown nonwoven fabric made of polyphthalamide resin according to the present invention or the battery separator according to the present invention, the lyophilic property of the surface of the nonwoven fabric can be improved by applying a surfactant. it can.

The present invention will be specifically described by the following examples and comparative examples. However, the present invention is not limited to these examples and the like.
In addition, each physical-property value in an Example and a comparative example is each calculated | required and measured by the following method.

(1) Fabric weight: A test piece of 100 × 100 mm was taken from the length direction of the non-woven fabric sample, and the weight of the moisture equilibrium state was measured and converted to the fabric weight per 1 m ² .
(2) Thickness: From the length direction of the non-woven fabric sample, a test piece of 100 × 100 mm was collected and measured with a dial thickness gauge.
(3) Air permeability: 100 × 100 mm non-woven fabric test specimens are collected from the length direction of the non-woven fabric sample, and in accordance with JIS L1096 “General fabric test method”, “Breathability A method (Fragile shape method)”. It measured using the tester.
(4) Tensile strength and tensile elongation: Measured at a sample width of 25 mm, a grip interval of 100 mm, and a tensile speed of 300 mm / min, in accordance with “Tensile strength and elongation” of JIS L1085 “Nonwoven fabric test method”.
(5) Fiber diameter: Five photos of non-woven fabric test pieces were taken with 5 electron microscopes, and the diameter of 20 fibers was measured per one photo. The diameter of 100 fibers was averaged.
(6) Heat shrinkage rate: In an oven set at 150 ° C. and 200 ° C., a line of about 10 cm is drawn in the MD direction (length direction) and CD angle direction (width direction) at the center and end of the 20 cm square nonwoven fabric sample. After heating for 24 hours, the line length was measured and the rate of change was determined.
(7) Electrolyte solution absorption speed: A horizontal bar of a predetermined height is placed on a water tank containing a solution in which PC (propylene carbonate) and DME (1,2-dimethoxyethane) are mixed at a weight ratio of 1: 1. Then, a non-woven fabric test piece (20 mm × 200 mm) was pinned to the horizontal bar, and then the horizontal bar was lowered to immerse the end of the sample piece in the mixed solution by 5 mm. After this immersion, capillary action occurred for 30 minutes. The height (mm) at which the mixed liquid rose was measured, and the measured value was taken as the liquid absorption rate of the electrolytic solution.
(8) Physical property evaluation after heating test Heating test method:
The nonwoven fabric test was held at the same temperature for a week in an oven set at 200 ° C.
Evaluation of the physical properties:
The tensile strength, the elongation, and the air permeability of the non-woven fabric after heat treatment were measured as the evaluation items of heat resistance by the above-mentioned method.

Reference Example 1
A polyphthalamide resin (Rilsan (registered trademark) HT melting point 255 ° C. manufactured by Arkema Co., Ltd.) was melt-kneaded at an extruder temperature of 350 ° C., and melt blown at a discharge rate of 2 g / min / hol using a 0.4 mm nozzle. Polyphthalamide melt blown nonwoven fabric (hereinafter referred to as “polyphthalamide”) having an average fiber diameter of 5.5 μm, basis weight of 15 g / m ² , thickness of 130 μm, air permeability of 150 cc / cm ² / sec, tensile strength of 10 N / 25 mm width, and tensile elongation of 52.1%. "Prototype 1" is obtained. The propylene carbonate absorption rate of Prototype 1 was 0 second 66. The heat shrinkage after heating at 150 ° C. for 24 hours was MD 0.5%, CD 0%, and the heat shrinkage at 200 ° C. for 24 hours was MD 1.0%, CD 1.0%.
In addition, after the prototype 1 was subjected to a heating test for one week in a 200 ° C. environment, the physical properties were evaluated, and the following results were obtained.
Tensile strength: 10.2 N / 25 mm width Tensile elongation: 46.5%
Permeability: 130 cc / cm ² / sec

Reference Example 2
The melt-blown nonwoven fabric obtained by the method of Reference Example 1 was subjected to calendering treatment at 150 ° C. with a metal / metal roll. The obtained calendered product (hereinafter referred to as “prototype 2”) has a basis weight of 15 g / m ² , a thickness of 38 μm, an air permeability of 37.5 cc / cm ² / sec, and a tensile strength of 12.1 N / 25 mm width, tensile The elongation was 45.5%, and the propylene carbonate absorption speed was 0 sec 88. The thermal shrinkage after heating at 150 ° C. for 24 hours was MD 0%, CD 0%, and the thermal shrinkage after heating for 24 hours at 200 ° C. was MD 0.5%, CD 0.5%. . Furthermore, when the calendered product was subjected to a heating test under a heating and holding condition for 1 week in a 200 ° C. environment, the tensile strength was 11.8 N / 25 mm width, the tensile elongation was 43.0%, and the air permeability was 11.5 cc. The result of / cm ² / sec was obtained.

Example 1
The melt-blown nonwoven fabric obtained by the method of Reference Example 1 was subjected to a calendering process at 150 ° C. using a metal / elastic roll. The obtained calendered product has a basis weight of 15 g / m ² , a thickness of 25 μm, an air permeability of 29.8 cc / cm ² / sec, a tensile strength of 17.5 N / 25 mm width, and a tensile elongation of 27.5%. Propylene carbonate The liquid absorption speed of 0 sec. The thermal contraction rate after heating and holding at 150 ° C. for 24 hours was MD 0% and CD 0%, and the thermal contraction rate after heating and holding at 200 ° C. for 24 hours were MD 0.5% and CD 0.5%. Furthermore, Table 1 shows the results of physical property evaluation after a heating test under a heating and holding condition for one week in a 200 ° C. environment.

Example 2
Melt-blown non-woven fabric obtained by treating under the same conditions as in Reference Example 1 except that a 0.3 mm ノ ズ ル nozzle was used instead of a 0.4 mm カ レ ン ダ ー nozzle, was calendered with a metal / elastic roll at 150 ° C. The product was subjected to processing to obtain a calendar processed product. The obtained calendered product has a basis weight of 20 g / m ² , a thickness of 33 μm, an air permeability of 8.5 cc / cm ² / sec, a tensile strength of 15.5 N / 25 mm, and a tensile elongation of 30.5%. The liquid absorption speed was 0 sec 83. The thermal contraction rate after heating and holding at 150 ° C. for 24 hours was MD 0% and CD 0%, and the thermal contraction rate after heating and holding at 200 ° C. for 24 hours was MD 0.5% and CD 0.5%. Furthermore, it shows in Table 1 about the result of the physical-property evaluation after the heating test on 200 degreeC environment on a 1-week heating holding condition.

Comparative Example 1
A melt blown nonwoven fabric was produced under the same conditions as in Reference Example 1 except that a polypropylene (PP) resin (MFR 1550 g / 10 min) was melt kneaded at an extruder temperature of 240 ° C. instead of the polyphthalamide resin. The obtained meltblown nonwoven fabric was subjected to a calendering treatment at 110 ° C. with a metal / elastic roll. The obtained calendered product has a basis weight of 14 g / m ² , a thickness of 27 μm, an air permeability of 0.3 cc / cm ² / sec, a tensile strength of 17.2 N / 25 mm width, and a tensile elongation of 16%. liquid velocity 100 seconds or more, the thermal shrinkage rate after 24 hours of heating maintained at 0.99 ° C. is MD6.0%, Ri Ah with CD5.5%, the thermal shrinkage rate after 24 hours of heating maintained at 200 ° C. is not measurable by melt Met. In addition, with regard to the evaluation of physical properties after the heating test under the heating and holding conditions for one week in a 200 ° C. environment, it was impossible to evaluate because the measurement was impossible due to melting .

Comparative example 2
Except that polybutylene terephthalate (PBT) resin was used in place of the polyphthalamide resin, all were melt blown under the same conditions as in Reference Example 1, and the resulting melt blown nonwoven fabric was subjected to the same conditions as in Example 1. Used for calendar processing. A calendered product obtained by calendering has a basis weight of 20 g / m ² , a thickness of 30 μm, an air permeability of 7 cc / cm ² / sec, a tensile strength of 28.4 N / 25 mm, and a tensile elongation of 11.9%. The absorption rate of the propylene carbonate liquid is 11 seconds 75, and the thermal contraction rate after heating and holding at 150 ° C. for 24 hours is MD 1.5%, CD 1.0%, thermal contraction after heating and holding at 200 ° C. for 24 hours The rates were MD 3.0% and CD 3.0%. Moreover, it shows in Table 1 about the result of the physical-property evaluation after the heat test of the environment hold | maintained for one week in a 200 degreeC environment.

Comparative example 3
Melt blow was performed under the same conditions as in Reference Example 1 except that nylon 6 resin was used instead of the polyphthalamide resin to obtain a melt blown nonwoven fabric. The obtained melt blown nonwoven fabric was subjected to calendering treatment under the same conditions as in Example 1. The calendered product has a basis weight of 20 g / m ² , a thickness of 30 μm, an air permeability of ^2.5 cc / cm ² / sec, a tensile strength of 72 N / 25 mm, a tensile elongation of 45.3%, and a polypropylene absorption speed of 3 seconds It was 88. The heat shrinkage after heating at 150 ° C. for 24 hours is MD 0.5%, CD 0.5%, and the heat shrinkage after heating at 200 ° C. for 24 hours is MD 1.5%, CD 1.5% Met. Furthermore, it shows in Table 1 about the result of the physical-property evaluation after the heating test on the heating conditions for one week in 200 degreeC environment.

Comparative example 4
The melt-blown nonwoven fabric was obtained by melt-blowing under the same conditions as in Reference Example 1 except that polyphenylene sulfide (PPS) resin was used instead of polyphthalamide resin. The resulting melt blown nonwoven fabric has a basis weight of 25 g / m ² , a thickness of 230 μm, an air permeability of 60 cc / cm ² / sec, a tensile strength of 17 N / 25 mm width, a tensile elongation of 25%, and a fiber diameter of 5 μm. Was 0 seconds 91. Moreover, the thermal shrinkage rate after heating and holding at 150 ° C. for 24 hours is MD 5.0% and CD 4.5%, and the thermal shrinkage rate after holding for 24 hours at 200 ° C. is MD 9.0% and CD 7.5%. Met. Furthermore, the physical property evaluation after the heating test under the heating and holding condition for one week in a 200 ° C. environment could not be measured due to shrinkage .

Comparative example 5
The melt blown nonwoven fabric obtained in Comparative Example 4 was subjected to a calendering treatment under the same conditions as in Reference Example 2 to obtain a calendered product. The calendered product has a basis weight of 25 g / m ² , a thickness of 50 μm, an air permeability of 13.0 cc / cm ² / sec, a tensile strength of 41.1 N / 25 mm width, and a tensile elongation of 3.8 %. The liquid velocity was 1 second 04 . The thermal contraction rate after heating and holding at 150 ° C. for 24 hours was MD 0% and CD 0%, and the thermal contraction rate after heating and holding at 200 ° C. for 24 hours were MD 2.0% and CD 0.5%. Furthermore, it shows in Table 1 about the result of the physical-property evaluation after the heating test on 200 degreeC environment on the heating conditions for one week.

Comparative Example 6
Although the melt-blown nonwoven fabric obtained in Comparative Example 4 was subjected to calendering treatment under the same conditions as the conditions of Example 1, cracks occurred in the calendered product and it became impossible to evaluate.

As is clear from Table 1, the meltblown nonwoven fabric comprising the polyphthalamide resin according to the present invention has a remarkably excellent thermal shrinkage by the above test method as compared with the meltblown nonwoven fabric obtained using other conventional raw material resins. Even in severe physical property evaluation after a severe heat test, excellent results can be obtained.

  The meltblown non-woven fabric made of the polyphthalamide resin according to the present invention can be suitably used as a battery separator excellent in heat resistance and electrolyte absorption speed, and can be applied to various battery manufacturing applications. In addition, since it is excellent in heat resistance and tensile strength, it is suitable for other applications such as separators for electric double layer capacitors, liquid filters for heat resistance, air filters for heat resistance, and other industrial materials requiring heat resistance. Can be used.

Claims (4)

A battery separator comprising a melt-blown non-woven fabric made of polyphthalamide resin ,
According to JIS K7210, the polyphthalamide resin has a melt flow rate of 10 to 1000 g / 10 min measured at a load of 5.0 kg and a temperature of 300 ° C., and a terephthalamide unit content of 50 mol. % Or more,
The melt blown nonwoven fabric has an average fiber diameter of 1 to 30 μm, a basis weight of 10 to 50 g / m ² , an air permeability of 1 to 50 cc / cm ² / sec, a thickness of 10 to 40 μm, a tensile strength of 2 to 50 N / 25 mm width, Tensile elongation is 10 to 50%,
Further, the heat shrinkage rate of the melt blown nonwoven fabric is 0.5% or less in at least one of the transverse direction and the longitudinal direction after the heat treatment at 200 ° C. for 24 hours, and the liquid absorption rate of the electrolytic solution propylene carbonate Is a battery separator, characterized in that is 3 seconds or less. Furthermore, the physical property evaluation related to the tensile strength, tensile elongation and air permeability after the heating test at 200 ° C. for one week is 80% each of the physical property evaluation related to the tensile strength, tensile elongation and air resistance before the heat test. The battery separator according to claim 1, which can be held as described above. It is a manufacturing method of the battery separator of Claim 1, Comprising:
After the polyphthalamide resin is melted at an extruder temperature of 260 to 380 ° C., it is fed into a die set at 300 to 380 ° C. and discharged from the die nozzle, and at the same time, it is drawn by a high-temperature air blow gas of 260 to 380 ° C. to draw fine fibers A method of manufacturing a battery separator, comprising: subjecting the obtained melt-blown nonwoven fabric to a calendering process at a temperature of 120 to 200 ° C . ;
In the battery separator, the calendering treatment is means for sandwiching and pressurizing the melt-blown nonwoven fabric between calender rolls having two pairs of roll materials, and the roll material is a metal / elastic body . Production method. The die has a nozzle hole diameter of 0.1 to 1 mmφ, a nozzle count of 5 to 20 / cm, and an amount of polyphthalamide resin discharged from the nozzle of 0.05 to 3 g / min / hole. The manufacturing method of the battery-cell separator of 3.