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Polyolefin microporous membrane

一种微多孔膜、聚烯烃制的技术，应用在膜、膜技术、半透膜分离等方向，能够解决热收缩率比小、电池性能烘烤试验不充分、生产方面不现实等问题，达到热收缩改善、优异电池安全性、优异电池特性的效果

Active Publication Date: 2008-12-24
ASAHI KASEI KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is not only unrealistic in terms of production to install a long-term heat relaxation and heat setting treatment process in the film forming process, but also the thermal shrinkage ratio of MD and TD is small, and it can be said that the battery performance is more important than the storage capacity of the battery winding body, the baking Insufficient roasting test
[0013] As described above, there is no separator that has high strength, excellent closed cell properties, high porosity, and excellent battery wound capacity and thermal shrinkage characteristics at high temperatures.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0125]95% by weight of polyethylene having a homopolymer of Mv of 250,000 and 5% by weight of polypropylene having a homopolymer of Mv of 400,000 were dry-blended using a tank mixer. Add 1 wt% pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as an antioxidant to the resulting 99 wt% pure polymer mixture, and dry again using a tank mixer Mix to obtain a mixture of polymers and the like. The resulting mixture of polymers and the like was replaced with nitrogen, and then supplied to a twin-screw extruder through a feeder under a nitrogen atmosphere. In addition, liquid paraffin (dynamic viscosity at 37.78°C is 7.59×10 -5 m 2 / s) into the extruder barrel.

[0126] Carry out melt kneading, adjust the feeder and pump, so that the proportion of liquid paraffin in the whole mixture extruded is 55wt%. Melting and kneading conditions were performed at a set temperature of 200° C., a screw rotation speed of 240 rpm, and a discharge rate of 12 kg / h.

[0127] ...

Embodiment 2

[0134] 47.5% by weight of polyethylene having a homopolymer of Mv of 700,000, 47.5% by weight of polyethylene having a homopolymer of Mv of 250,000, and 5% by weight of polypropylene of a homopolymer of Mv of 400,000 were dry-blended using a tank mixer. Add 1 wt% pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] as an antioxidant to the resulting 99 wt% pure polymer mixture, and dry again using a tank mixer Mix to obtain a mixture of polymers and the like. The resulting mixture of polymers and the like was replaced with nitrogen, and then supplied to a twin-screw extruder through a feeder under a nitrogen atmosphere. In addition, liquid paraffin (dynamic viscosity at 37.78°C is 7.59×10 -5 m 2 / s) into the extruder barrel.

[0135] Melt kneading was carried out, and feeders and pumps were adjusted so that the ratio of the amount of liquid paraffin to the entire mixture extruded was 65 wt%. Melting and kneading conditions were performed at a set tempe...

Embodiment 3

[0143] After being extruded onto the cooling roll, casting is carried out by embankment molding, the biaxial stretching temperature is set to 118°C, the heat setting temperature is set to 122°C, and the coiled parent roll is placed in a constant temperature room at 60°C for 6 hours. , except that, it carried out similarly to Example 2, and obtained the microporous film.

[0144] Table 1 shows the physical properties of the obtained microporous membrane.

[0145] As a result of the battery evaluation, all of them were good results.

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Abstract

Disclosed is a polyolefin microporous membrane having a thickness of not less than 1[mu]m and not more than 50 [mu]m, a porosity of not less than 30 percent and not more than 70 percent, a puncture strength in terms of a 1[mu]m thick film of not less than 0.15 N / [mu]m, a tensile strength in the machine direction (MD tensile strength) of not less than 30 MPa, a tensile strength in the transverse direction (TD tensile strength) of not less than 30MPa, a thermal shrinkage at 65 DEG C in the transverse direction (TD thermal shrinkage) of not more than 1 percent, and a ratio between the thermal shrinkage at 65 DEG C in the machine direction and the thermal shrinkage at 65 DEG C in the transverse direction (MD thermal shrinkage / TD thermal shrinkage) of more than 2. Also disclosed are a method for producing such a polyolefin microporous membrane and a nonaqueous electrolyte secondary battery using such a polyolefin microporous membrane.

Description

technical field [0001] The present invention relates to microporous membranes widely used as separation membranes used in the separation of substances, selective permeation, etc., and as separators for electrochemical reaction devices such as alkaline secondary batteries, lithium secondary batteries, fuel cells, and capacitors Wait. In particular, it relates to a polyolefin microporous film suitable as a separator for lithium ion batteries. Background technique [0002] Polyolefin microporous membranes are widely used as separation membranes, separators, and the like for separation and selective permeation of various substances. For example, polyolefin microporous membranes are used as microfiltration membranes, separators for fuel cells, separators for capacitors, base materials for functional membranes in which pores are filled with functional materials to express new functions, separators for batteries, and the like. Among these uses, the polyolefin microporous film is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J9/00H01M2/16C08J9/26H01M10/40H01M10/052H01M10/36H01M50/417H01M50/491H01M50/494
CPCB01D71/26B01D2323/20B01D2325/24C08J5/2231H01M10/052C08J2323/02Y10T428/268Y02E60/10H01M50/417H01M50/491H01M50/494C08J9/22C08J9/26C08J5/22H01M10/05B01D71/261
Inventor 饭谷和也稻垣大助
Owner ASAHI KASEI KK
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