JP3741410B2 - Alkaline battery separator and method for producing the same - Google Patents

Description

Ａ：セパレータの表面を構成する繊維の外側表面を、発生する光電子の脱出角度３０°の条件で、Ｘ線光電子分光計により測定した時の、５３０．５〜５３１．５ｅＶに結合エネルギーのピークを有する物質の検出の有無
Ｂ：セパレータの表面を構成する繊維の外側表面を、発生する光電子の脱出角度９０°の条件で、Ｘ線光電子分光計により測定した時の、５３０．５〜５３１．５ｅＶに結合エネルギーのピークを有する物質の検出の有無
Ｃ：セパレータの表面を構成する繊維の外側表面と、セパレータ内部を構成する繊維の表面とをＸ線マイクロアナライザーにより測定した時の、表面領域におけるカルボキシル基の有無
【００８４】
（Ｘ線電子分光計による測定方法）
なお、Ｘ線光電子分光計による測定はＸ線光電子分光計（ＪＰＳ−９０１０ＭＸ、日本電子社製）を用いて、次の条件にて測定した。
セパレータを純水で洗浄した後乾燥し、サンプルホルダーに固定した。次いで到達真空度１０−６Ｐａ（パスカル）の下で、励起源（Ｘ線源）としてＭｇ−Ｋαを用い、印加電圧値１０ＫＶ、ビーム電流１０ｍＡの条件で対象表面を測定した。
【００８５】
（容量維持率）
実施例１〜７及び比較例１〜２のセパレータの容量維持率は、表１に示す通りであった。なお、容量維持率の測定は詳細な説明中に記載した手順で行った。
【００８６】
（サイクル寿命試験）
実施例１〜７及び比較例１〜２のセパレータの寿命を、次のようにして測定した。まず、電極の集電体として、発泡ニッケル基材を用いたペースト式ニッケル正極（３３ｍｍ、１８２ｍｍ長）と、ペースト式水素吸蔵合金負極（メッシュメタル系合金、３３ｍｍ、２４７ｍｍ長）とを作成した。次いで、３３ｍｍ幅、４１０ｍｍ長に裁断した実施例１〜６及び比較例１〜２のセパレータを、それぞれ正極と負極との間に挟み込み、渦巻き状に巻回して、ＳＣ型対応の電極群をそれぞれ作成した。この電極群を外装缶に収納し、電解液として５Ｎ−水酸化カリウム及び１Ｎ−水酸化リチウムを外装缶に注液し、封缶して円筒型ニッケル−水素電池を作成した。次いで、それぞれの円筒型ニッケル−水素電池を、０．２Ｃ、１５０％充電と、１Ｃ放電、終止電圧１．０Ｖ放電からなる充放電サイクルを繰り返し、放電容量が初期容量の５０％となるまでの、充放電サイクル数を測定した。この結果は表１に示す通りであった。
【００８７】
表１から明らかなように、本発明のセパレータを使用したニッケル−水素電池は、耐酸化性、自己放電抑制作用に優れ、長期間使用できるものであった。
【００８８】
【発明の効果】
本発明のアルカリ電池用セパレータは繊維シートを含むものであり、このセパレータ表面を構成する繊維の外側表面を、Ｘ線光電子分光計により測定した場合に、５３０．５〜５３１．５ｅＶ（エレクトロンボルト）に結合エネルギーのピークを有する物質が検出されるものである。この５３０．５〜５３１．５ｅＶに結合エネルギーのピークを有する物質は、酸素原子及び／又は酸素分子であると考えられ、過充電時等に酸素が発生したとしても、既に酸素原子及び／又は酸素分子が存在することにより、更なる酸化はほとんど進行しないと考えられるため、酸素による劣化の生じにくいセパレータである。
【００８９】
さらに、本発明のセパレータは、セパレータ表面を構成する繊維の表面よりも、セパレータ内部を構成する繊維の表面に、より多くのカルボキシル基が存在しているものである。このように、セパレータの表面近傍において、酸化されやすいカルボキシル基が少ないため、耐酸化性に優れている。また、セパレータの内部を構成する繊維の表面にはカルボキシル基が存在しているため、電解液の保持性に優れている。
【００９０】
本発明のセパレータ製造方法によれば、セパレータ表面を構成する繊維の外側表面に酸素原子及び／又は酸素分子が存在すると考えられるセパレータ、つまり耐酸化性に優れるセパレータを容易に製造することができ、また、セパレータ内部を構成する繊維表面により多くのカルボキシル基が存在するセパレータ、つまり耐酸化性に優れ、電解液の保持性にも優れるセパレータを容易に製造することができる。
【図面の簡単な説明】
【図１】 実施例１のセパレータ表面を構成する繊維の外側表面を、発生する光電子の脱出角度３０°で、Ｘ線光電子分光計により測定したチャート
【図２】 比較例１のセパレータ表面を構成する繊維の外側表面を、発生する光電子の脱出角度３０°で、Ｘ線光電子分光計により測定したチャート[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alkaline battery separator and a method for producing the same. More specifically, alkaline primary batteries such as alkaline manganese batteries, mercury batteries, silver oxide batteries, air batteries, nickel-cadmium batteries, silver-zinc batteries, silver-cadmium batteries, nickel-zinc batteries, nickel-hydrogen batteries. The present invention relates to a separator that can be used for an alkaline secondary battery such as a rechargeable alkaline manganese battery, and in particular, a separator that can be suitably used for a battery that generates oxygen at the time of overcharging, such as a nickel-cadmium battery or a nickel-hydrogen battery, and its It relates to a manufacturing method.
[0002]
[Prior art]
Conventionally, a separator is used so that a positive electrode and a negative electrode of an alkaline battery are separated to prevent a short circuit, and an electrolysis reaction can be smoothly performed while holding an electrolytic solution. Since this separator needs to hold an electrolytic solution made of potassium hydroxide or the like, a fiber sheet composed of polyolefin fibers having excellent alkali resistance is preferable.
[0003]
However, since polyolefin fibers have low affinity with electrolytes and electrolyte retention is very poor, fiber sheets composed of polyolefin fibers can be hydrophilized in various ways to retain electrolytes. Gave the ability.
[0004]
As one of the hydrophilic treatment methods, there is a method of graft polymerization of a vinyl monomer. For example, in 1994 Special Table No. 509208, a separator in which a vinyl monomer is graft-polymerized on a fabric made of polyolefin fiber, a step of impregnating a cloth made of polyolefin fiber with a solution of vinyl monomer, and oxygen A process for producing a separator is disclosed which comprises a step of irradiating a fabric with ultraviolet light under conditions that do not expose.
[0005]
However, if a separator with graft polymerization of vinyl monomer is used in a nickel-cadmium battery or nickel-hydrogen battery, the separator deteriorates due to oxygen generated during overcharging, and a short circuit occurs, or deterioration due to oxygen is extremely high. This may affect the plate and shorten the battery life.
[0006]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an alkaline battery separator that is not easily deteriorated by oxygen generated inside the battery, and to provide a manufacturing method thereof.
[0007]
[Means for Solving the Problems]
The separator for an alkaline battery of the present invention includes a fiber sheet. When the outer surface of the fiber constituting the separator surface is measured by an X-ray photoelectron spectrometer, 530.5 to 531.5 eV (electron bolt) In this case, a substance having a binding energy peak is detected. The substance having a binding energy peak at 530.5 to 531.5 eV is considered to be an oxygen atom and / or an oxygen molecule. Even if oxygen is generated during overcharge or the like, the oxygen atom and / or oxygen is already generated. Since it is considered that further oxidation hardly proceeds due to the presence of molecules, it is a separator that is hardly deteriorated by oxygen.
[0008]
In addition, when oxygen exists in the bonded state of C = 0 or 0-C = 0, it is detected as having a peak at 532 to 533 eV, and also exists in the bonded state of C—O. Is detected as having a peak at 533.5 to 534.5 eV, and it is detected as having a peak at 530.5 to 531.5 ev in a specific binding state other than the above. It is estimated that In addition, since the measurement by the X-ray photoelectron spectrometer is performed in a vacuum state, a substance that is simply present on the surface in a physically attached state should be detached during the measurement and not be detected. In any case, when a vinyl monomer or polymer is graft-polymerized by a conventional method, a substance having a binding energy peak at 530.5 to 531.5 eV is not detected.
[0009]
Further, the separator of the present invention, when measured by an X-ray microanalyzer, the outer surface of the fiber constituting the surface and the surface of the fiber constituting the inside of the separator, on the surface of the fiber constituting the inside of the separator, More carboxyl groups are present by bonding. Thus, since there are few carboxyl groups which are easy to oxidize in the surface vicinity of a separator, it is excellent in oxidation resistance. In addition, since the carboxyl group is bonded and present on the surface of the fiber constituting the inside of the separator, the retention of the electrolytic solution is excellent.
[0010]
In the method for producing a separator of the present invention, a fiber sheet to which a monomer or polymer capable of graft polymerization is attached is subjected to a graft polymerization treatment in the presence of oxygen, and then the periphery of the fiber sheet is surrounded by a non-breathable film. In this method, a graft polymerization treatment is further performed. When graft polymerization is first performed in the presence of oxygen as in this method, the monomer or polymer is graft-polymerized, and at the same time, a reaction that adsorbs oxygen atoms and / or oxygen molecules on the outer surface of the fibers constituting the fiber sheet surface. Is also expected to progress. Next, when the fiber sheet is surrounded by a non-breathable film and further graft polymerization is performed in this state, a reaction for adsorbing oxygen atoms and / or oxygen molecules on the outer surface of the fibers constituting the fiber sheet surface also proceeds. However, it is considered that the graft polymerization on the surface of the fiber constituting the inside of the fiber sheet proceeds to impart hydrophilicity to the fiber sheet. As described above, according to the method of the present invention, a separator that is considered to have oxygen atoms and / or oxygen molecules bonded to the outer surface of the fibers constituting the separator surface, that is, a separator having excellent oxidation resistance, is easily manufactured. be able to. In addition, if a monomer or polymer having a carboxyl group is used, a separator having more carboxyl groups on the fiber surface constituting the inside of the separator, that is, a separator having excellent oxidation resistance and excellent electrolyte retention. It can be manufactured easily.
DETAILED DESCRIPTION OF THE INVENTION
[0011]
The “fibers constituting the separator surface” in the present invention refers to fibers that can partly or entirely circumscribe the virtual plane among the fibers constituting the separator. Further, the “outer surface” refers to a surface that is circumscribed with a virtual plane of the fibers that constitute the separator surface.
[0012]
In this invention, when measuring the outer surface of the fiber which comprises the separator surface with a X-ray photoelectron spectrometer, it measures on the conditions from which the escape angle of the generated photoelectron becomes about 30 degrees. This is detected by the X-ray photoelectron spectrometer when the escape angle is the smallest (that is, the region closest to the surface) 530.5-when measured under a plurality of conditions with different escape angles of the generated photoelectrons. A detected amount of a substance having a binding energy peak at 531.5 eV is detected when the escape angle is larger than when the escape angle is the smallest (that is, including a region deeper than when the escape angle is the smallest). This is because it is preferably larger than the detected amount of a substance having a binding energy peak at 530.5 to 531.5 eV.
[0013]
That is, when a region close to the surface contains a large number of oxygen atoms and / or oxygen molecules, the oxidation resistance is excellent, and in a deeper region, oxygen atoms and / or oxygen can be retained. This is because fewer molecules are preferable. For example, when the measurement is performed under the condition that the photoelectron escape angle is 30 ° and the photoelectron escape angle is 90 °, the photoelectron escape angle is 30 °. The detection amount of the substance having a binding energy peak at 5 to 531.5 eV is detected under the condition that the photoelectron escape angle is 90 °. The substance having the binding energy peak at 530.5 to 531.5 eV is detected. It is preferable that the amount is larger than the detected amount.
[0014]
When the separator of the present invention measures the outer surface of the fiber constituting the separator surface and the surface of the fiber constituting the inside of the separator with an X-ray microanalyzer, the surface of the fiber constituting the inside of the separator has more carboxyl. A group is present. Thus, in the region that can be measured by the X-ray microanalyzer on the outer surface of the fiber constituting the separator surface (hereinafter referred to as “surface region”), since there are few carboxyl groups that are easily oxidized, the oxidation resistance is excellent. In the region that can be measured by the X-ray microanalyzer on the surface of the fiber constituting the separator interior (hereinafter referred to as “internal region”), the retention of the electrolytic solution is excellent because there are many carboxyl groups. Moreover, there exists a tendency which is excellent in the self-discharge suppression effect by being in such a state. It is preferable that no carboxyl group is present in the surface region so that the oxidation resistance is excellent.
[0015]
The separator of this invention contains fiber sheets, such as a textile fabric, a knitted fabric, a nonwoven fabric, or these composites, for example. Among these, it is preferable to include a nonwoven fabric that is structurally excellent in electrolyte retention. The fiber sheet is preferably made of fibers having a fineness of 0.01 to 3 denier so as to have an appropriate denseness for preventing a short circuit and air permeability such as generated gas.
[0016]
Examples of the fibers constituting the fiber sheet of the present invention include nylon fibers, vinylon fibers, vinylidene fibers, polyvinyl chloride fibers, polyester fibers, acrylic fibers, polyurethane fibers, polyolefin fibers such as polypropylene fibers and polyethylene fibers, and the like. One or more synthetic fibers can be used. Among these, polyolefin fibers having excellent alkali resistance can be preferably used.
[0017]
Examples of suitable polyolefin fibers include polymers of monomers such as propylene, ethylene, butene, and methylpentene, copolymers of two or more of these monomers, or copolymers of these monomers with vinyl alcohol, acrylic acid, and methacrylic acid. Resin components such as a polymer (for example, ethylene-vinyl alcohol copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, etc.) can be contained. The polyolefin-based fiber can be a single fiber composed only of the resin component as described above, or can be a composite fiber composed of two or more types of the resin component as described above. As the latter composite fiber, those having a fiber cross-sectional shape such as a core-sheath type, a side-by-side type, an eccentric type, a sea-island type, an orange type, and a multiple bimetal type can be used.
[0018]
In addition, when the polyolefin fiber has various characteristics, various characteristics can be imparted to the separator. For example, when a polyolefin fiber is separable by physical action and / or chemical action, ultrafine fibers (preferably 0.02-0.3 denier) having a fineness of 0.01-0.5 denier can be generated. Therefore, it is possible to improve the retention of the electrolytic solution, increase the capacity, or extend the life. Note that when a polyolefin fiber having a fineness of more than 0.5 denier is used, an appropriate void can be formed to provide a separator having excellent gas permeability (for example, oxygen permeability). In addition, when the polyolefin fiber is heat-fusible, the tensile strength and rigidity of the separator can be improved, so that the battery can be assembled efficiently. Furthermore, the tensile strength (tensile strength specified in JIS L 1015 (chemical fiber staple test method)) is 5 g / denier or more (preferably 6 g / denier or more, more preferably 9 g / denier or more, and further preferably 12 g / denier). As described above, most preferably 25 g / denier or more) polyolefin fiber is used, and when the electrode plate group of the battery is manufactured, the electrode plate breaks, the burr of the electrode plate penetrates through the separator, or the electrode plate group is short-circuited. It can be set as the separator which is hard to be torn by an edge. The polyolefin fiber having a tensile strength of 5 g / denier or higher has a high degree of crystallinity and tends not to proceed with the graft reaction. Therefore, it is preferably 40 mass% or less of the fibers constituting the separator, and 30 mass%. The following is more preferable. In addition, in order to exhibit the above effects, it is preferable that it is 5 mass% or more of the fiber which comprises a separator, and it is more preferable that it is 10 mass% or more.
[0019]
In addition, when hydrophilicity is imparted by graft polymerization, since the polyethylene resin is easily graft polymerized, the amount exceeding 60% of the total surface of the fibers constituting the fiber sheet before graft polymerization is composed of the polyethylene resin. Is preferred. In addition, when the resin component constituting the fiber surface is made of an ethylene-vinyl alcohol copolymer, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, etc., the graft reaction rate is increased and the fiber itself is also hydrophilic. Therefore, it is preferable.
[0020]
The separator of the present invention has a chemical oxygen demand (hereinafter referred to as “COD”) of 250 mg · O / m. ² It is preferable that: This COD is 250mg · O / m ² If it exceeds, the deterioration due to oxygen is remarkable, and the battery using this separator may have a short life. More preferably, the COD is 230 mg · O / m ² Or less, most preferably 220 mg · O / m ² It is as follows.
[0021]
The value of COD can be obtained, for example, by the following method.
(1) The separator is cut to such a size that 20 to 40% of the potassium permanganate described later acting as an oxidizing agent is consumed (area Am). ² ). For example, the separator is cut into 5 cm square (area 0.0025 m). ² ).
(2) The above separator is further cut into a size of about 1 to 2 cm square, and then put into a 300 ml (milliliter) flask.
(3) Inject 100 ml (milliliter) of pure water into the flask with a graduated cylinder.
(4) Pour sulfuric acid water consisting of 2 volumes of distilled water against 1 volume of sulfuric acid, and pour it into a 10 ml (milliliter) flask.
(5) A 5 mmol / l (N / 40) potassium permanganate solution is poured into a 10 ml (milliliter) flask with a pipette and shaken, and immediately placed in a hot water bath (with a shaker) at 80 ° C. and allowed to react for 30 minutes. . At this time, the reaction is sufficiently performed so that the water surface of the hot water bath is above the water surface in the flask. Moreover, after making it react for 30 minutes, it confirms that the red color of potassium permanganate remains. When the color disappears, it means that the amount of the separator is too large. Therefore, the operations of (1) to (5) are repeated with the amount of the separator reduced.
(6) Remove the flask from the hot water bath and inject 10 ml (milliliter) of a 12.5 mmol / l (N / 40) sodium oxalate solution into the flask with a pipette, and shake well to react well. At this time, it is confirmed that the red color of potassium permanganate disappears and becomes colorless.
(7) Titrate with 5 mmol / l (N / 40) potassium permanganate solution while keeping the solution in the flask at 60-80 ° C. The end point is when the slight red color is kept for 30 seconds or more. The amount a (ml) of the potassium permanganate solution required at this time is measured.
(8) Separately, 100 ml (milliliter) of pure water is placed in an Erlenmeyer flask and the operations (4) to (7) are performed (blank test). The amount b (ml) of the potassium permanganate solution required at this time is measured.
(9) From the above results, COD is calculated by the following equation.
COD (mg · O / m 2) = (ab) × f × 0.2 × 1 / A
a: Amount of potassium permanganate required for titration (ml)
b: Amount of potassium permanganate required for the titration of the blank test (ml)
f: Factor of 5 mmol / l potassium permanganate solution
A: Area of separator (m2)
[0022]
Moreover, it is preferable that the capacity | capacitance maintenance factor of the battery (especially nickel-hydrogen battery) using the separator of this invention is 60% or more. This is because if the capacity retention ratio is less than 60%, the battery life tends to be short or the electrolyte retainability tends to be poor.
[0023]
The capacity retention rate of this battery is a value obtained by the following method.
(1) A paste type nickel positive electrode (33 mm width, 182 mm length) using a foamed nickel base and a paste type hydrogen storage alloy negative electrode (mesh metal alloy 33 mm width, 247 mm length) were prepared as the current collector of the electrode. To do.
(2) A separator cut to a width of 34 mm and a length of 410 mm is sandwiched between the positive electrode and the negative electrode described in (1) and wound in a spiral shape to create an SC-type electrode group.
(3) The SC-type electrode group is housed in an outer can, and 5N-potassium hydroxide and 1N-lithium hydroxide are injected into the outer can as an electrolyte, and then sealed and cylindrical nickel-hydrogen battery Create
(4) The initial capacity (A) of the cylindrical nickel-hydrogen battery of (3) at 0.1 C discharge and a final voltage of 1.0 V is measured.
(5) Charge 150% (capacity ratio) at 0.1 C and leave at 65 ° C. for 5 days.
(6) The capacity (B) at 0.1 C discharge and final voltage of 1.0 V is measured.
(7) From the above results, the capacity maintenance rate is calculated by the following equation.
Capacity maintenance rate (%) = (B / A) × 100
[0024]
In the separator of the present invention, a fiber sheet to which a graft-polymerizable monomer or polymer is attached is subjected to a graft polymerization treatment in the presence of oxygen, and then the fiber sheet is surrounded by a non-breathable film. It can manufacture by performing a graft polymerization process.
[0025]
Examples of the fiber sheet to which the graft-polymerizable monomer or polymer is attached (hereinafter referred to as “fiber sheet before treatment”) include, for example, a woven fabric, a knitted fabric, a nonwoven fabric, or a composite thereof. These pre-treated fiber sheets can be easily produced by conventional methods. For example, a suitable non-woven fabric can be produced as follows.
[0026]
First, a fiber web is formed by a wet method or a dry method (for example, a card method, an air lay method, a melt blow method, a spun bond method, etc.) using fibers as described above, preferably polyolefin fibers. The fiber length generally varies depending on the method of forming the fiber web. When the fiber web is formed by a wet method, a short fiber having a fiber length of about 1 to 25 mm is used, and a dry method such as a card method or an air array method is used. When forming a fiber web by the method, a long fiber having a fiber length of about 25 to 110 mm is used. This fiber web does not need to be composed of a single layer, and different types of fiber webs such as a fiber web obtained by a wet method and a fiber web obtained by a dry method or a fiber web having a different fiber composition may be laminated. In particular, a laminate of a fiber web by a wet method and a fiber web by a dry method has both the uniformity of the fiber web by the wet method and the strength of the fiber web by the dry method.
[0027]
The fiber web can then be bonded to produce a nonwoven fabric. As this bonding method, for example, (1) a method of entanglement with a fluid flow such as a water flow, and (2) a heat-fusible fiber is mixed as a fiber constituting the fiber web, and the heat-fusible fiber is mixed. There are a method of fusing part or all, (3) a method of bonding partly or entirely with a binder, and (4) a method of using them together. In addition, as described above, when the fiber web by the wet method and the fiber web by the dry method are laminated, the fiber web by the wet method and the fiber web by the dry method are not distinguished, and substantially one layer of nonwoven fabric. In order to be able to do, it is preferable to make it intertwined by fluid flows, such as a water flow. Moreover, when the splitting fiber which can be divided | segmented into an ultrafine fiber by the physical effect | action is included, there exists an effect that the splitting of a splitting fiber can be simultaneously carried out with a fluid flow. Further, it is preferable to fuse the heat-fusible fiber because the tensile strength and bending resistance of the separator can be improved.
[0028]
Subsequently, the monomer or polymer which can be graft-polymerized is made to adhere to the fiber sheet before a process. Examples of the graft-polymerizable monomer include a vinyl monomer, and examples of the vinyl monomer include acrylic acid, α-ethylacrylic acid, crotonic acid, isocrotonic acid, vinyl acetic acid, methacrylic acid, angelic acid, tiglic acid, and allylic acetic acid. , Α-ethylcrotonic acid, cinnamic acid, 10-undecenoic acid, oleic acid, elaidic acid, erucic acid, brassic acid, rumecic acid, sorbic acid, linoleic acid, eleostearic acid, linolenic acid, arachidonic acid, acetylenecarboxylic acid Acid, tetrolic acid, stearic acid, behenolic acid, xymenic acid, and other unsaturated monocarboxylic acids, derivatives of these unsaturated monocarboxylic acids such as esters, maleic acid, fumaric acid, methylmaleic acid, methylfumaric acid, glutaconic acid , Itaconic acid, allylmalonic acid, terraco Unsaturated dicarboxylic acids such as acid, muconic acid and butynedioic acid, derivatives such as esterified products of these unsaturated dicarboxylic acids, unsaturated tricarboxylic acids such as aconitic acid, derivatives such as esterified products of this unsaturated tricarboxylic acid, or Examples include vinyl pyridine, vinyl pyrrolidone, and styrene. Such graft polymerizable monomers can be used alone or in admixture. In addition, when styrene is included as a monomer that can be graft-polymerized, it is preferably further sulfonated.
[0029]
Among these graft-polymerizable monomers, unsaturated monocarboxylic acids or unsaturated dicarboxylic acids in which a carboxyl group is directly bonded to carbon having a double bond can be suitably used because they are easily graft-polymerized, and among these, acrylic acid Methacrylic acid can be suitably used because it is easy to control the polymerization, and also produces good hydrophilicity by graft polymerization.
[0030]
Moreover, as a polymer which can be graft-polymerized, what polymerized the above monomers can be used, and it is preferable to use polyacrylic acid or polymethacrylic acid from a reactive point.
[0031]
Examples of a method for attaching such a graft-polymerizable monomer or polymer to a fiber sheet before treatment include, for example, (1) a method of applying or spraying a solution containing the monomer or polymer to the fiber sheet before treatment, (2) monomer or There is a method of immersing a fiber sheet before treatment in a solution containing a polymer. If the mass ratio of the monomer or polymer in the solution is too large, the oxidation resistance tends to be inferior, and if it is too small, the retention of the electrolyte and the self-discharge suppressing action tend to decrease, so 5-60 mass%. Is preferred.
[0032]
In addition, it is preferable to mix a sensitizer, surfactant, a chain transfer agent, etc. with the solution containing a monomer or a polymer. In particular, when a chain transfer agent is mixed, it is considered that the graft chain can be shortened, and this is suitable for production since it is excellent in washing and removing properties such as unreacted homopolymer. Further, it is preferable to first perform graft polymerization in the presence of oxygen using a solution containing a monomer or polymer containing a chain transfer agent in the presence of oxygen as will be described later. Thus, when it is excellent in the self-discharge suppressing action, the graft ratio can be lowered, and as a result, there is also a secondary effect that the oxidation resistance is improved.
[0033]
Examples of the chain transfer agent include alcohols such as isopropyl alcohol, polyfunctional alcohols such as polyethylene glycol, dicarboxylic acids such as maleic acid, and the like. When such a chain transfer agent is used to improve the self-discharge suppressing action, oxidation resistance, or washing and removal of unreacted homopolymer, it is contained in a solution containing the monomer or polymer in an amount of 3 mass% or more. Is preferred. The upper limit is not particularly limited, but it is suitably 70 mass% or less (more preferably 50 mass% or less) in the solution containing the monomer or polymer.
[0034]
In addition, when a solution containing an extra monomer or polymer is included in the pre-treatment fiber sheet, the solution containing the monomer or polymer is unevenly distributed by gravity, and as a result, graft polymerization occurs in an unevenly distributed state. It is preferred to squeeze out a solution containing excess monomer or polymer. That is, the solution containing the monomer or polymer contained in the fiber sheet before treatment is preferably 40 to 250, more preferably 50 to 170, with respect to the surface density 100 of the fiber sheet before treatment. Examples of means for squeezing out the solution containing the extra monomer or polymer include a method of passing between a pair of rolls and a method of passing between a flat plate press.
[0035]
Before adhering the monomer or polymer-containing solution to the fiber sheet before treatment, in order to improve the familiarity between the solution containing the monomer or polymer and the fiber sheet before treatment, treatment with ultraviolet irradiation, corona discharge, plasma discharge, etc. It is preferable to perform the surface treatment of the front fiber sheet.
[0036]
Next, the pre-treated fiber sheet to which the graft polymerizable monomer or polymer is attached is subjected to graft polymerization in the presence of oxygen. In this graft polymerization, at the same time as the monomer or polymer is graft-polymerized, a substance (oxygen) having a binding energy peak at 530.5 to 531.5 eV (electron volts) on the outer surface of the fiber constituting the fiber sheet surface before treatment. It is considered that the reaction of adsorbing (which is considered to be atoms and / or oxygen molecules) proceeds, and therefore the oxidation resistance of the separator can be improved. Further, even if a monomer having a carboxyl group is used as a graft-polymerizable monomer or polymer, even if the carboxyl group is hardly present or present on the outer surface of the fiber constituting the fiber sheet surface before treatment, Since the amount is small, it is considered that the oxidation resistance of the separator can be improved. In the graft polymerization in the presence of oxygen, it suffices if oxygen is present, and it may be carried out in the air or while supplying oxygen. This is preferable.
[0037]
Examples of the graft polymerization method in the presence of oxygen include ultraviolet irradiation, far-infrared irradiation, radiation irradiation (X rays, α rays, β rays, γ rays), thermal polymerization, and the like. Among these, ultraviolet irradiation is preferable because it can be graft-polymerized only on the fiber surface, and the radical generation time of the photoinitiator is short and the graft polymerization can be performed in a short time.
[0038]
Next, the fiber sheet graft-polymerized in the presence of oxygen is surrounded by a non-breathable film, and in that state, further graft polymerization treatment is performed to impart hydrophilicity. Surrounding the fiber sheet with a non-breathable film can prevent further evaporation of the adhering polymerizable monomer or polymer. In the second polymerization process at this stage, the graft chain is easily grafted to the monomer or polymer already grafted by graft polymerization in the presence of oxygen. It is thought to extend. Therefore, since the graft polymerization is likely to proceed on the surface of the fiber constituting the inside of the fiber sheet before treatment, when a monomer or polymer having a carboxyl group is used, on the surface of the fiber constituting the inside of the fiber sheet, Many carboxyl groups are present by bonding. It is considered that the adsorption of oxygen atoms and / or oxygen molecules to the fibers on the fiber sheet surface side further proceeds.
[0039]
Examples of the graft polymerization method in the surrounding state using the non-breathable film include ultraviolet irradiation, far-infrared irradiation, radiation irradiation (X-rays, α-rays, β-rays, γ-rays), and thermal polymerization. It should be noted that the graft polymerization in the presence of oxygen and the graft polymerization in the surrounding state with the non-breathable film may be the same or different in other polymerization conditions.
[0040]
The ratio of the graft polymerization treatment time in the presence of oxygen as described above and the graft polymerization treatment time in a state where the periphery of the fiber sheet is surrounded by a non-breathable film is not particularly limited, but is 1: 8 to 5: 4 is preferred. When the graft polymerization time in the presence of oxygen is shorter than 1: 8, the amount of the substance having a binding energy peak at 530.5 to 531.5 eV on the outer surface of the fiber constituting the separator surface is reduced, and the oxidation resistance is increased. If the graft polymerization time in the presence of oxygen is longer than 5: 4, the graft polymerization at the next stage is difficult to proceed, the electrolyte retention is reduced, and the self-discharge characteristic is suppressed. It is difficult to do this, and as a result, the capacity retention rate tends to decrease, and more preferably 2: 7 to 5: 4.
[0041]
The pre-processed fiber sheet thus graft-polymerized is in a state containing some unreacted materials. Therefore, in order to remove these, the fiber sheet should be sufficiently washed with water, hot water, hot water, alcohol or the like. preferable.
[0042]
The graft ratio is not particularly limited, but is preferably 3% or more (preferably 5% or more) in order to impart hydrophilicity and electrolyte retention. On the other hand, it is preferably 25% or less (preferably 20% or less) so that appropriate air permeability can be ensured and oxidation resistance is not lowered. The graft rate is 1m ² The value obtained by dividing the per graft amount by the surface density of the separator.
[0043]
About the separator of this invention which can be manufactured as mentioned above, it can further hydrophilize by methods, such as surfactant processing, a fluorine processing, and a discharge process, and can improve initial liquid absorption performance. It is preferable to add a surfactant that is considered to have a small influence on oxygen atoms and / or oxygen molecules that are considered to be present on the outer surface of the fiber constituting the separator surface, and more specifically, a nonionic surfactant. Is preferably 0.1 to 3 mass%, more preferably 0.2 to 1.5 mass%, and most preferably 0.3 to 0.8 mass%.
[0044]
Since the separator of the present invention is excellent in oxidation resistance, it can be suitably used for batteries that generate oxygen during overcharge, such as nickel-cadmium batteries and nickel-hydrogen batteries. Of course, other alkaline batteries, for example, alkaline primary batteries such as alkaline manganese batteries, mercury batteries, silver oxide batteries, air batteries, silver-zinc batteries, silver-cadmium batteries, nickel-zinc batteries, rechargeable alkaline manganese batteries, etc. It can also be suitably used as a separator for alkaline secondary batteries.
[0045]
Examples of the present invention will be described below, but the present invention is not limited to the following examples. In addition, the measurement by the X-ray microanalyzer in the outer surface of the fiber which comprises the surface of a separator, and the surface of the fiber which comprises the inside of a separator was performed in the following procedure.
(1) The separator is immersed in a 1N aqueous hydrochloric acid solution for 2 hours.
(2) After sufficiently washing with water, it is immersed in a 1N aqueous potassium hydroxide solution for 2 hours to replace hydrogen with potassium.
(3) Wash thoroughly with water and dry.
(4) Measure potassium using an energy dispersive X-ray microanalyzer.
[0046]
【Example】
Example 1
A core-sheath fusible fiber having a fineness of 1.1 denier and a fiber length of 10 mm (100% high-density polyethylene occupies the fiber surface) is composed of polypropylene as the core component and high-density polyethylene (melting point: 132 ° C.) as the sheath component. ) A fiber web was formed from the slurry in which 100 mass% was dispersed by a conventional wet papermaking method. Next, this fiber web was heat-treated at 136 ° C., and then passed through between rolls having a linear pressure of 10 N / cm, and high-density polyethylene as a sheath component of the core-sheath fusible fiber was fused to form a nonwoven fabric.
[0047]
On the other hand, the following compounding liquid was prepared.
(1) Acrylic acid monomer: 25 mass%
(2) Benzophenone: 0.3 mass%
(3) Iron sulfate: 0.4 mass%
(4) Nonionic surfactant: 3 mass%
(5) Water: 71.3 mass%
[0048]
Next, after immersing the above-mentioned nonwoven fabric in the above-described blended liquid (containing 80 blended liquids with respect to the non-woven fabric surface density of 100), 180 mw / cm from a metal halide mercury lamp arranged on each side of the nonwoven fabric. ² Acrylic acid was graft-polymerized by irradiating ultraviolet rays centered at 365 nm in air for 15 seconds at an illuminance of 2 nm. Next, the nonwoven fabric was sandwiched between non-breathable films, and 180 mW / cm from a metal halide mercury lamp, one on each side of the nonwoven fabric. ² Then, ultraviolet light having a center of 365 nm was irradiated for 15 seconds at an illuminance of, and further, acrylic acid was graft polymerized. Next, the graft-polymerized nonwoven fabric was sufficiently washed with water and dried, and then calendered with a linear pressure of 10 N / cm to obtain a surface density of 60.8 g / m. ² A separator having a thickness of 0.15 mm and a graft rate of 9.8% was manufactured.
[0049]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected (see FIG. 1). Moreover, when the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it has a binding energy peak at 530.5 to 531.5 eV. No material was detected.
[0050]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0051]
(Comparative Example 1)
After the nonwoven fabric formed in the same manner as in Example 1 was immersed in the same blending solution as in Example 1 (containing 80 blending liquids with respect to the surface density of the nonwoven fabric of 100), the nonwoven fabric was formed with a non-breathable film. 180 mW / cm from a metal halide mercury lamp placed between the nonwoven fabric, one on each side ² Acrylic acid was graft-polymerized by irradiating ultraviolet rays having a center of 365 nm for 30 seconds at an illuminance of 3 nm. Next, the graft-polymerized nonwoven fabric was sufficiently washed with water and dried, and then calendered with a linear pressure of 10 N / cm to obtain an area density of 59.8 g / m. ² A separator having a thickness of 0.15 mm and a graft ratio of 10.5% was manufactured.
[0052]
The outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition that the escape angle of the generated photoelectrons was 30 °, and the binding energy was 530.5 to 531.5 eV (electron volts). The substance which has the peak of was not detected at all (refer FIG. 2).
[0053]
Moreover, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured with an X-ray microanalyzer, the same level of carboxyl groups existed in both the surface region and the inner region. Was.
[0054]
(Example 2)
It has an orange cross section consisting of a polypropylene component (cross-sectional shape is fan-shaped, melting point: 160 ° C.) and a high-density polyethylene component (cross-sectional shape is fan-shaped, melting point: 130 ° C.), and a water flow having a fineness of 2 denier and a fiber length of 10 mm. Splittable fiber (can produce 8 polypropylene ultrafine fibers with a fineness of 0.125 denier and 8 high density polyethylene ultrafine fibers with a fineness of 0.125 denier) 70 mass% and the core component is made of polypropylene A slurry obtained by mixing and dispersing 30 mass% of core-sheath fusible fiber having a fineness of 2 denier and a fiber length of 10 mm, which is made of low-density polyethylene (melting point: 110 ° C.), is used as a fiber by a conventional wet papermaking method. A web was formed.
[0055]
Next, this fiber web was heat-treated at 115 ° C. to fuse only the low-density polyethylene component of the core-sheath fusible fiber. Next, the fused fiber web is placed on a net having a wire diameter of 0.15 mm, and a water flow having a pressure of 12.7 MPa is alternately applied to both sides of the nozzle plate having a nozzle diameter of 0.13 mm and a pitch of 0.6 mm twice. It ejected and the division | segmentation of the splittable fiber and the fiber entanglement were performed. Thereafter, the entangled fiber web was heat treated at 115 ° C., and only the low density polyethylene component of the core-sheath fusible fiber was fused again to form a nonwoven fabric. Subsequently, the graft polymerization was carried out in exactly the same manner as in Example 1, sufficiently washed with water, dried, and calendered with a linear pressure of 10 N / cm to obtain a surface density of 60.5 g / m. ² A separator having a thickness of 0.15 mm and a graft rate of 10% was produced.
[0056]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected. Moreover, when the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it has a binding energy peak at 530.5 to 531.5 eV. No material was detected.
[0057]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0058]
Example 3
In the same manner as in Example 2, the surface density was 35 g / m. ² A wet fiber web was formed. On the other hand, except that the splittable fiber of Example 2 and the fiber length are 38 mm, exactly the same splittable fiber 70 mass%, and the core-sheath type fusible fiber of Example 2 and the fiber length are 38 mm. The same core-sheath fusible fiber 30 mass% is blended and opened with a card machine, and the surface density is 20 g / m. ² A unidirectional fiber web was formed. Next, the wet fiber web and the unidirectional fiber web were laminated to form a laminated fiber web.
[0059]
Subsequently, the laminated fiber web was fused in the same manner as in Example 2 with the fusion of the low-density polyethylene component of the core-sheath fusible fiber, the entanglement of the fibers by the water flow and the splitting of the splittable fibers, and the core-sheath fusibility. The low-density polyethylene component of the fiber was re-fused in order to form a nonwoven fabric in which short fibers and long fibers were uniformly entangled so as to be substantially one layer. Next, graft polymerization was performed in exactly the same manner as in Example 1, sufficiently washed with water, dried, and calendered with a linear pressure of 10 N / cm to obtain a surface density of 59.2 g / m 2, a thickness of 0.15 mm, and a graft ratio of 10 A 2% separator was produced.
[0060]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected. Moreover, when the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it has a binding energy peak at 530.5 to 531.5 eV. No material was detected.
[0061]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0062]
(Example 4)
The following blending solution was prepared.
(1) Acrylic acid monomer: 25 mass%
(2) Benzophenone: 0.3 mass%
(3) Iron sulfate: 0.4 mass%
(4) Nonionic surfactant: 3 mass%
(5) Water: 61.3 mass%
(6) Polyethylene glycol (degree of polymerization: 400): 10 mass%
[0063]
Next, except that the non-woven fabric formed in the same manner as in Example 1 was immersed in the blending solution as described above, the graft polymerization was performed in the same manner as in Example 1, washed sufficiently with water, dried, and then subjected to a linear pressure of 10 N / cm. Calendered with a surface density of 60.3 g / m ² A separator having a thickness of 0.15 mm and a graft ratio of 9.9% was manufactured.
[0064]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected. In addition, when the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it was measured under the condition of an escape angle of generated photoelectrons of 30 ° Although less, a substance having a binding energy peak at 530.5 to 531.5 eV was detected.
[0065]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0066]
(Comparative Example 2)
After the nonwoven fabric formed in the same manner as in Example 1 was immersed in the same blending solution as in Example 4 (containing 80 blending liquids with respect to the surface density of the nonwoven fabric of 100), the nonwoven fabric was formed with a non-breathable film. 180 mW / cm from a metal halide mercury lamp placed between the nonwoven fabric, one on each side ² Acrylic acid was graft polymerized by irradiating with ultraviolet light at the center of 365 nm for 30 seconds at an illuminance of. Next, the graft-polymerized nonwoven fabric was sufficiently washed with water and dried, and then calendered with a linear pressure of 10 N / cm to obtain a surface density of 60 g / m. ² A separator having a thickness of 0.15 mm and a graft ratio of 11% was produced.
[0067]
The outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition that the escape angle of the generated photoelectrons was 30 °, and the binding energy was 530.5 to 531.5 eV (electron volts). No substance having a peak was detected.
[0068]
Moreover, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured with an X-ray microanalyzer, the same level of carboxyl groups existed in both the surface region and the inner region. Was.
[0069]
(Example 5)
The following blending solution was prepared.
(1) Acrylic acid monomer: 25 mass%
(2) Benzophenone: 0.3 mass%
(3) Iron sulfate: 0.4 mass%
(4) Nonionic surfactant: 3 mass%
(5) Water: 51.3 mass%
(6) Isopropyl alcohol: 20 mass%
[0070]
Next, except that the non-woven fabric formed in the same manner as in Example 1 was immersed in the blending solution as described above, the graft polymerization was performed in the same manner as in Example 1, washed thoroughly with water, dried, and then subjected to a linear pressure of 10 N / cm. Calendered with a surface density of 60.4 g / m ² A separator having a thickness of 0.15 mm and a graft rate of 9.8% was manufactured.
[0071]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected. In addition, when the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it was measured under the condition of an escape angle of generated photoelectrons of 30 ° Although less, a substance having a binding energy peak at 530.5 to 531.5 eV was detected.
[0072]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0073]
(Example 6)
The following blending solution was prepared.
(1) Acrylic acid monomer: 25 mass%
(2) Benzophenone: 0.3 mass%
(3) Iron sulfate: 0.4 mass%
(4) Nonionic surfactant: 3 mass%
(5) Water: 61.3 mass%
(6) Maleic acid: 10 mass%
[0074]
Subsequently, the non-woven fabric formed in the same manner as in Example 1 was graft-polymerized in exactly the same manner as in Example 1 except that it was immersed in the above-described blending solution, sufficiently washed with water, dried, and then at a linear pressure of 10 N / cm. Calendar processing, surface density 59.2g / m ² A separator having a thickness of 0.15 mm and a graft rate of 9.2% was manufactured.
[0075]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected. In addition, when the outer surface of the fiber constituting the separator surface is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it is measured under the condition of an escape angle of generated photoelectrons of 30 ° Although less, a substance having a binding energy peak at 530.5 to 531.5 eV was detected.
[0076]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0077]
(Example 7)
The core component is made of polypropylene, the sheath component is made of high-density polyethylene (melting point: 132 ° C.), the core-sheath type heat-sealable fiber 80 mass% with a fineness of 0.7 denier and the fiber of 5 mm, the fineness of 2 denier, and the fiber length of 10 mm. A fiber web was formed by a wet papermaking method from a slurry in which 20% by mass of high-strength polypropylene fiber having a tensile strength of 9 g / denier was dispersed. Next, after heat-treating this fiber web at 136 ° C., the high-density polyethylene which is the sheath component of the core-sheath type heat-fusible fiber is fused between rolls (at room temperature) having a linear pressure of 10 N / cm to form a nonwoven fabric Formed.
[0078]
On the other hand, the following compounding liquid was prepared.
(1) Acrylic acid monomer: 30 mass%
(2) Benzophenone: 0.1 mass%
(3) Iron sulfate: 0.4 mass%
(4) Nonionic surfactant: 1 mass%
(5) Polyethylene glycol (degree of polymerization: 400): 10 mass%
(6) Water: 58.5 mass%
[0079]
Next, after impregnating the non-woven fabric with the compounded liquid (containing the compounded liquid at a ratio of 80 with respect to the non-woven fabric surface density of 100), 180 mW / cm from a metal halide mercury lamp arranged on each side of the non-woven fabric. ² Acrylic acid was graft-polymerized by irradiating ultraviolet rays centered at 365 nm in air for 15 seconds at an illuminance of 2 nm. Acrylic acid was hardly graft polymerized to the fibers present in the surface layer of the nonwoven fabric, and was graft polymerized to the fibers present inside the surface layer of the nonwoven fabric.
[0080]
Next, the nonwoven fabric was sandwiched between non-breathable films so as not to apply pressure to the nonwoven fabric from both sides so as to allow the presence of air in the nonwoven fabric, and 180 mW / cm from a metal halide mercury lamp arranged one by one on both sides of the nonwoven fabric. ² Acrylic acid was further polymerized on the graft copolymer formed in the above-mentioned step by irradiating ultraviolet rays centered at 365 nm in air for 15 seconds at an illuminance of 5 nm. Next, the graft-polymerized nonwoven fabric is washed thoroughly with water and dried, and then calendered with a linear pressure of 10 N / cm to obtain a surface density of 60.8 g / m. ² , Thickness 0.15 mn, graft ratio. A 9.8% separator was produced.
[0081]
A substance having a binding energy peak at 530.5 to 531.5 eV when the outer surface of the fiber constituting the surface of the separator is measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °. Was detected. Further, when the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, it had a binding energy peak at 530.5 to 531.5 eV. No material was detected.
[0082]
Further, when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator were measured by an X-ray microanalyzer, no carboxyl group was present in the surface region, and the inner region Only had a carboxyl group.
[0083]
(COD)
The CODs of the separators of Examples 1 to 7 and Comparative Examples 1 and 2 were as shown in Table 1. The COD was measured according to the procedure described in the detailed description.
[Table 1]

A: When the outer surface of the fiber constituting the separator surface is measured by an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 30 °, a peak of binding energy is observed at 530.5 to 531.5 eV. Detection of substances
B: When the outer surface of the fiber constituting the surface of the separator was measured with an X-ray photoelectron spectrometer under the condition of an escape angle of generated photoelectrons of 90 °, a peak of binding energy was observed at 530.5 to 531.5 eV. Detection of substances
C: Presence / absence of carboxyl groups in the surface region when the outer surface of the fiber constituting the surface of the separator and the surface of the fiber constituting the inside of the separator are measured with an X-ray microanalyzer
[0084]
(Measurement method by X-ray electron spectrometer)
The X-ray photoelectron spectrometer was measured using the X-ray photoelectron spectrometer (JPS-9010MX, manufactured by JEOL Ltd.) under the following conditions.
The separator was washed with pure water, dried, and fixed to the sample holder. Subsequently, under the ultimate vacuum of 10 −6 Pa (Pascal), the target surface was measured using Mg—Kα as an excitation source (X-ray source) under the conditions of an applied voltage value of 10 KV and a beam current of 10 mA.
[0085]
(Capacity maintenance rate)
The capacity retention rates of the separators of Examples 1 to 7 and Comparative Examples 1 and 2 were as shown in Table 1. The capacity retention rate was measured according to the procedure described in the detailed description.
[0086]
(Cycle life test)
The lifetimes of the separators of Examples 1 to 7 and Comparative Examples 1 and 2 were measured as follows. First, a paste-type nickel positive electrode (33 mm, 182 mm length) using a foamed nickel substrate and a paste-type hydrogen storage alloy negative electrode (mesh metal alloy, 33 mm, 247 mm length) were prepared as electrode current collectors. Next, the separators of Examples 1 to 6 and Comparative Examples 1 and 2 cut to a width of 33 mm and a length of 410 mm were sandwiched between the positive electrode and the negative electrode, respectively, wound in a spiral shape, and SC-type electrode groups were respectively formed. Created. This electrode group was housed in an outer can, and 5N potassium hydroxide and 1N-lithium hydroxide were poured into the outer can as an electrolytic solution and sealed to prepare a cylindrical nickel-hydrogen battery. Next, each cylindrical nickel-hydrogen battery was subjected to a charge / discharge cycle consisting of 0.2C, 150% charge, 1C discharge, and final voltage 1.0V discharge until the discharge capacity reached 50% of the initial capacity. The number of charge / discharge cycles was measured. The results are shown in Table 1.
[0087]
As is clear from Table 1, the nickel-hydrogen battery using the separator of the present invention was excellent in oxidation resistance and self-discharge suppressing action and could be used for a long time.
[0088]
【The invention's effect】
The separator for an alkaline battery of the present invention includes a fiber sheet. When the outer surface of the fiber constituting the separator surface is measured by an X-ray photoelectron spectrometer, 530.5 to 531.5 eV (electron bolt) In this case, a substance having a binding energy peak is detected. The substance having a binding energy peak at 530.5 to 531.5 eV is considered to be an oxygen atom and / or an oxygen molecule. Even if oxygen is generated during overcharge or the like, the oxygen atom and / or oxygen is already generated. Since it is considered that further oxidation hardly proceeds due to the presence of molecules, it is a separator that is hardly deteriorated by oxygen.
[0089]
Further, the separator of the present invention has more carboxyl groups on the surface of the fibers constituting the inside of the separator than on the surface of the fibers constituting the separator surface. Thus, since there are few carboxyl groups which are easy to oxidize in the surface vicinity of a separator, it is excellent in oxidation resistance. Moreover, since the carboxyl group exists in the surface of the fiber which comprises the inside of a separator, it is excellent in the retainability of electrolyte solution.
[0090]
According to the separator manufacturing method of the present invention, it is possible to easily manufacture a separator that is considered to have oxygen atoms and / or oxygen molecules on the outer surface of the fibers constituting the separator surface, that is, a separator having excellent oxidation resistance. Moreover, the separator which has many carboxyl groups on the fiber surface which comprises the inside of a separator, ie, the separator which is excellent in oxidation resistance, and is excellent also in the retainability of electrolyte solution, can be manufactured easily.
[Brief description of the drawings]
FIG. 1 is a chart in which an outer surface of a fiber constituting a separator surface of Example 1 is measured by an X-ray photoelectron spectrometer at an escape angle of generated photoelectrons of 30 °.
FIG. 2 is a chart obtained by measuring the outer surface of the fiber constituting the separator surface of Comparative Example 1 with an X-ray photoelectron spectrometer at an escape angle of generated photoelectrons of 30 °.

Claims (4)

An alkaline battery separator (hereinafter simply referred to as a “separator”) including a fiber sheet, and an X-ray photoelectron spectrometer on the outer surface of a fiber constituting the separator surface under a condition that a photoelectron escape angle is 30 degrees A separator for alkaline batteries, characterized in that a substance showing a peak of binding energy at 530.5 to 531.5 eV (electron volts) when measured by the above method is present. A separator including a fiber sheet, characterized in that more carboxyl groups are present on the surface of the fiber constituting the separator than the outer surface of the fiber constituting the separator surface, Separator for alkaline batteries. A separator for an alkaline battery including a fiber sheet, wherein the outer surface of the fiber constituting the separator surface has 530.5 or more when measured by an X-ray photoelectron spectrometer under a condition that a photoelectron escape angle is 30 degrees. There is a substance that shows a peak of binding energy at 531.5 eV (electron bolt), and more carboxyl groups are bound to the surface of the fiber constituting the separator than to the outer surface of the fiber constituting the separator surface. A separator for an alkaline battery, wherein the separator is present. After graft polymerization treatment is performed on the fiber sheet to which the graft-polymerizable monomer and / or polymer is attached in the presence of oxygen, the fiber polymerization sheet is further subjected to graft polymerization treatment in a state surrounded by a non-breathable film. A method for producing an alkaline battery separator.

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