JP2008150723A - Polyketone fiber paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyketone fiber paper having heat resistance, strength and liquid permeability and to provide a separator paper for a battery and a capacitor. <P>SOLUTION: The polyketone fiber paper is obtained as follows: Short fibers or fibril fibers of fibers composed of a polyketone in which ≥95 mol% of repeating units is represented by formula (1) of -CH<SB>2</SB>CH<SB>2</SB>CO- are formed into a paper. The resultant paper is then impregnated or coated with a purified solution of a paper strengthening agent free of impurities. The tensile strength is 1.0-3.0 kg/10 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to paper and paper used for batteries and separators for capacitors, and relates to paper and separator paper having excellent paper strength.

In recent years, a paper having excellent heat resistance and high paper strength has been demanded as a functional paper. In particular, heat resistance and paper strength are required for separator paper used for capacitors or batteries. In order to bring out these characteristics, various improvements have been made on the paper manufacturing method for the constituent materials, not only for the pulp materials, but also for combinations of other plural materials.
In patent document 1, the polyketone fiber paper excellent in the high intensity | strength and heat resistance by the fiber paper by a polyketone fiber raw material is proposed. In order to obtain paper and to obtain its strength, it is disclosed that the press working is performed at a high temperature of a melting point temperature of −40 to + 40 ° C. and a processing linear pressure of 1 to 200 KN / cm. In the field of synthetic paper, especially in the field where the basis weight is required to be as low as 10 to 70 g / m ² as in the separator field, the tensile strength required in the process cannot be obtained, and the density increases and the air permeability, There was a problem that liquid permeability was difficult to obtain.

International Publication No. 06-077779 Pamphlet

  The present invention provides a polyketone paper, a battery, and a separator paper for a capacitor that meets such requirements.

The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems.
That is, the present invention is as follows.
The first of the present invention is a paper on which 95 mol% or more of the repeating units are made of short fibers and / or fibril fibers composed of a polyketone represented by the following formula (1). Polyketone fiber paper, which is bonded with a paper strength enhancer.

  In the second aspect of the present invention, the paper strength enhancer is selected from polyethylene imine resin, polyacrylamide resin, carboxymethyl cellulose, guar gum, locust bean gum, tragacanth gum, corn starch, potato starch, dialdehyde starch, cationic starch, methyl cellulose, urea resin. The above-mentioned first polyketone fiber paper, characterized in that it is one type or two or more types.

  According to the present invention, a polyketone paper having excellent heat resistance, low elution of impurities and excellent paper strength, and battery and capacitor separator paper having low internal resistance are provided.

The present invention will be specifically described below.
In the polyketone constituting the polyketone fiber of the present invention, 95 mol% or more, preferably 98 mol% or more, particularly preferably 99.6 mol% or more of the repeating unit is represented by the above formula (1). Within a range of less than mol%, a repeating unit other than the above formula (1), for example, one represented by the following formula (2) may be contained.

但し式中、Ｒは、エチレン以外の炭素数１〜３０の有機基であり、例えば、プロピレン、ブチレン、１−フェニルエチレン等の基であり、Ｒの水素原子の一部または全部が、ハロゲン基、エステル基、アミド基、水酸基、エーテル基で置換されていてもよい。もちろん、Ｒは二種以上であってもよく、例えば、プロピレンと１−フェニルエチレンが混在していてもよい。

In the formula, R is an organic group having 1 to 30 carbon atoms other than ethylene, for example, a group such as propylene, butylene, 1-phenylethylene, etc., and a part or all of the hydrogen atoms of R are halogen groups. , An ester group, an amide group, a hydroxyl group, and an ether group may be substituted. Of course, two or more types of R may be used. For example, propylene and 1-phenylethylene may be mixed.

式中のｔ及びＴは、それぞれヘキサフルオロイソプロパノール（セントラル硝子（株）社製）及び該ヘキサフルオロイソプロパノールに溶解したポリケトンの希釈溶液の２５℃での粘度管の流過時間である。Ｃは、上記希釈溶液の濃度であり、ヘキサフルオロイソプロパノール１００ｍｌ中のポリケトンの質量（ｇ）である。 The intrinsic viscosity [η] of the polyketone is preferably 1 dl / g or more, more preferably 2 dl / g or more, particularly preferably 4 dl / g or more, 20 dl / g or less, 15 dl / g or less, 10 dl / g or less. It is preferable.
The intrinsic viscosity [η] is a value obtained based on the following definition formula.

In the formula, t and T are the flow times of the viscosity tube at 25 ° C. of hexafluoroisopropanol (manufactured by Central Glass Co., Ltd.) and a dilute solution of polyketone dissolved in the hexafluoroisopropanol, respectively. C is the concentration of the diluted solution and is the mass (g) of polyketone in 100 ml of hexafluoroisopropanol.

The polyketone may contain additives such as antioxidants, radical inhibitors, other polymers, matting agents, ultraviolet absorbers, flame retardants, and metal soaps as necessary.
Next, as preferable characteristics of the polyketone fiber, the tensile strength is 5 cN / dtex or more, more preferably 10 cN / dtex or more, particularly preferably 15 cN / dtex or more, 30 cN / dtex or less, and the tensile elongation is 3%. Or more, more preferably 3.5% or more, particularly preferably 4% or more, 8% or less, more preferably 7% or less, particularly preferably 6% or less, and the tensile elastic modulus is 100 cN / dtex or more, more Preferably it is 200 cN / dtex or more, Most preferably, it is 300 cN / dtex or more, and is 1000 cN / dtex or less.

Polyketone short fibers are obtained by cutting long fibers. The shape may be uniform or thick in the length direction, and the cross-sectional shape of the fiber may be round, triangular, L-shaped, T-shaped, Y-shaped, W-shaped, Yaba-shaped, flat-shaped ( It has a flatness of about 1.3 to 4, including W type, I type, Boomerang type, wave type, skewer type, eyebrows type, rectangular parallelepiped type, etc.), polygonal type such as dogbone type, many It may be a leaf type, a hollow type, or an irregular shape. The preferred single yarn fineness is 0.01 to 10 dtex, more preferably 0.1 to 10 dtex, particularly preferably 0.5 to 5 dtex, and in the case of monofilament yarn, the range is 10 to 100,000 dtex.

The fiber length of the polyketone short fiber is preferably 0.3 to 20 mm, more preferably 1 to 10 mm, and particularly preferably 3 to 7 mm.
Polyketone fibril fibers are obtained from those beaten in a beater, refiner, or high-pressure homogenizer. Preferably, it is by refiner processing, and particularly preferably by conical refiner processing. Fibril fibers processed with a conical refiner are preferred because of their large specific surface area and large fiber length.
As a specific surface area of a fibril fiber, 1-20 m < ² > / g is preferable, More preferably, it is 3-15 m < ² > / g. The fiber length of the fibril fiber is preferably 0.3 to 5 mm, more preferably 0.5 to 5 mm.

Basis weight of the polyketone fiber paper is preferably 10~70g / m ^2, more preferably from 10 to 50 g / m ^2, is less than 10 g / m ^2, without the paper with a uniform strength can be obtained and, 70 g / If it exceeds m ² , the thickness of the separator will increase, making it difficult to obtain a compact and high-capacity capacitor.
The thickness of the polyketone fiber paper is preferably 15 to 100 μm, more preferably 15 to 50 μm.
The tensile strength needs to be 1.0 kg / 10 mm or more. The upper limit is 3 kg / 10 mm. If the upper limit is exceeded, the rigidity becomes high and the use in the separator becomes difficult.

In the present invention, the paper strength enhancer solution is impregnated and applied so as to be fixed at the adhesion point between the fibers in the paper layer. As the paper strength enhancer, one or two selected from polyethyleneimine resin, polyacrylamide resin, carboxymethylcellulose, guar gum, locust bean gum, tragacanth gum, corn starch, potato starch, dialdehyde starch, cationic starch, methylcellulose, urea resin Use one or more seeds and impregnate and apply 1.0 to 4.0% by weight. Further, in order to reduce the impurities in the paper, it is preferable to remove the impurities in the paper strength enhancer, and it is preferable to purify the paper.
Examples of the coating method of the paper strength enhancer include a dip method, a spray method, and a roll coater method. After coating, the liquid is drained by a press roll, and then dried by hot air drying, a cylinder drying method, or the like to produce paper.

The combination ratio of the polyketone short fibers and the fibril fibers is not particularly limited, and may be 0 to 100% short fibers and 100 to 0% pulp.
Polyketone fibers and other fibers may be mixed. Examples of other fibers include natural fibers, regenerated fibers, inorganic fibers, and synthetic fibers. Examples of natural fibers include cellulose fibers such as face, hemp, and wood, and examples of regenerated fibers include rayon and cupra. Examples of the inorganic fiber include glass fiber and carbon fiber. Examples of the synthetic fiber include polyethylene, polypropylene, nylon, polyester, polyacrylonitrile, wholly aromatic polyamide fiber, polyparaphenylene benzobisoxazal, polyimide fiber, and Teflon (registered trademark) fiber. Further, one type of other fibers or a combination of a plurality of types can be mixed for paper making. As a ratio which mixes another fiber, 1 to 30 weight% is preferable.

The present invention will be described more specifically based on examples, but the present invention is not limited to these examples.
The measurement method and evaluation method in the present invention are as follows.
(1) After drying a paper having a basis weight of 0.05 cm ² or more to a constant weight at 105 ° C.,
The weight was measured after standing in a constant temperature room of 65% RH for 16 hours or more, and the weight per 1 m ² was determined.

(2) Tensile strength Measured according to JIS-P-8113.
Measurement was performed at a sample width of 15 mm and a tensile speed of 20 mm / min, and the average value was measured 10 times.
(3) Air permeability Measured according to JIS-L-1096 (Fragile test method).
Obtain the average value when measured 5 times.

[Example 1]
1670 dtex / 1250f polyketone fiber (manufactured by Asahi Kasei Fibers Co., Ltd .; trade name: Cyvalon; tensile strength 18 cN / dtex, tensile elongation 5%, tensile elastic modulus 350 cN / dtex) The polyketone long fibers were cut into 3 mm short fibers using a cutter device. Then, it was beaten with a conical refiner to obtain a polyketone fibril fiber having a specific surface area of 8 m ² / g.
Paper making was performed with a wet method using 100% of the obtained fibril fibers to obtain a polyketone fiber paper having a basis weight of 50 g / m ² . The obtained polyketone fiber paper was immersed in a dilute solution of polyethyleneimine resin purified with an ion exchange resin with a roll coater, and the liquid was adjusted with a press roll so that the polyethyleneimine was 3.5% by weight with respect to the paper. Then, it dried at 110 degreeC with the hot press machine for 5 minutes, and obtained paper. Table 1 shows the measurement results of the obtained paper.
As a result of evaluating the tensile strength and the air permeability, the obtained paper was strong and had a high air permeability.

[Example 2]
The 3 mm short fiber obtained in Example 1 was beaten with a conical refiner, and the fibril fiber having a specific surface area of 8 m ² / g was mixed at a weight ratio of 50:50. And a polyketone fiber paper having a basis weight of 50 g / m ² was obtained. The obtained polyketone fiber paper is immersed in a dilute solution of polyethyleneimine resin purified with an ion exchange resin with a roll coater, and adjusted with a press roll so that polyethyleneimine is 3.5% by weight with respect to the paper. The paper was dried by a hot press machine at 110 ° C. for 5 minutes. Table 1 shows the measurement results of the obtained paper.
[Comparative Example 1]
The polyketone fibril fiber obtained by the same production method as in Example 1 was paper-made to obtain a paper having a basis weight of 50 g / m ² . This was calendered at a processing temperature of 260 ° C. and a processing linear pressure of 200 KN / cm to obtain a paper. Table 1 shows the measurement results of the obtained paper.

  The present invention provides a polyketone fiber paper excellent in heat resistance, strength, and liquid permeability, and the paper is used as separator paper for batteries and capacitors.

Claims (2)

95 mol% or more of the repeating units are paper made from short fibers and / or fibril fibers composed of polyketone represented by the following formula (1), and the polyketone fibers are bonded to each other with a paper strength enhancer. Polyketone fiber paper, characterized by

  One or two paper strength enhancers selected from polyethyleneimine resin, polyacrylamide resin, carboxymethylcellulose, guar gum, locust bean gum, tragacanth gum, corn starch, potato starch, dialdehyde starch, cationic starch, methylcellulose, urea resin The polyketone fiber paper according to claim 1, which is as described above.