【発明の詳細な説明】[Detailed description of the invention]
本発明は密閉形鉛蓄電池に関するものであり、
安価で寿命性能が優れ、使用中に電解液の減少が
少ない保守の不要な密閉形鉛蓄電池を提供するこ
とを目的とするものである。
近時、この種の鉛蓄電池としては、繊維径が
0.2〜5μm程度の微細なガラス短繊維をマツト状
にした隔離体を使用するものが実用されており、
優れた性能を示している。しかしながらこの種の
微細なガラス繊維は高価であり、これを使用した
ものでは鉛蓄電池の価格が上昇するという欠点を
有していた。
このため安価な隔離体を得るべく様々な提案が
なされている。例えば特公昭42−8402号公報に
は、含水無晶形酸化珪素の粉状体を抄紙液として
ガラス繊維を叩解抄紙し、不完全乾燥を施したの
ち耐酸、耐酸化性樹脂懸濁液または溶液に浸漬し
て乾燥、熱処理を施した隔離体が提案されてい
る。しかしながらこの隔離体では酸化珪素が耐酸
化性樹脂で固定されているため電解液に該酸化珪
素が直接作用することがなく、よつて特に電解液
の量を制限したいわゆる密閉形鉛蓄電池に適用し
た場合、液枯れが発生するという欠点がある。
また特公昭47−40733号公報には繊維径４〜
10μのガラス繊維の短片と、これにより遥かに細
い鉱物繊維の短片とを適当割合に水に分散させ
て、ガラスマツト上に流下させることによつて該
ガラスマツト上に繊維の微孔層を抄造するものが
提案されているが、このように形成した隔離体で
はガラスマツトからその上部の微孔層が剥離して
２層に分離するとともに、孔径が大きく電解液の
保持力と吸収度が不充分であるという欠点を有し
ている。さらにこの隔離体を密閉形鉛蓄電池に用
いた場合、微孔層とガラスマツトとの電解液吸収
度が極端に違つているために、電池の中で電解液
の偏在が生じ電池寿命が極端に短かいという大き
な欠点を有している。
また特公昭55−29579号公報、特開昭55−30194
号公報などには、合成繊維と無機粒子を主体とす
る各種の電池用隔離体が提案されているが、それ
らはいずれも流動する電解液を有する鉛蓄電池に
用いるべくいずれもその多孔度がせいぜい約60％
程度のものであり、密閉形鉛蓄電池用としては電
解液の含液量が充分でないなどの理由により適用
できないものである。
本発明は安価で、しかも従来の微細なガラス繊
維を用いたものに比べ遜色のない性能を有する密
閉形鉛蓄電池を提供することを目的とするもので
あり、この種の鉛蓄電池において一種類あるいは
複数種類の耐酸、耐酸化性を有する合成繊維30〜
３重量％と、耐酸性を有する無機微粉末70〜97重
量％とで構成された多孔度75％以上の隔離体を、
正極板と負極板との間に配置したことを特徴とす
るものである。すなわち従来の微細なガラス短繊
維をマツト状にした隔離体がガラス繊維を主材と
して構成され、本質的にその電解液をガラス繊維
間の空隙で保持しているのに対し、本発明では電
解液の保持機能を無機微粉末に持たせ、該無機微
粉末の支持体として、また強度を持たせる目的で
合成繊維を配置したことを特徴とするものであ
る。
以下、本発明のいくつかの実施例および、これ
らとそれ以外のものとの比較試験にもとづき本発
明を詳細に説明する。長さ約10mmで繊維径が公称
0.5デニールのポリプロピレン繊維、長さ約５mm
で公称４デニールのポリエステル繊維、および長
さ約５mmで公称３デニールのアクリル繊維をそれ
ぞれ単独もしくは混ぜ合わせた合成繊維と、無機
微粉末としてシリカ粉末あるいは珪藻土を水中で
分散させ抄紙装置により抄紙成形し20Kg／cm2の荷
重下で厚さが1.5mmの隔離体を得た。試作した隔
離体を構成する素材の配合比（隔離体に対する重
量比）と、特性およびコストを第１表に示す。ま
た、第１表には比較のために従来のものとして繊
維径が0.5〜1.0μの微細なガラス繊維100％からな
る隔離体についての特性をも合わせ記載した。な
おそれぞれの隔離体のコストについては従来のも
のの材料価格を100とした時の比率で示した。
The present invention relates to a sealed lead acid battery,
The object of the present invention is to provide a sealed lead-acid battery that is inexpensive, has excellent life performance, reduces electrolyte loss during use, and requires no maintenance. Recently, this type of lead-acid battery has a fiber diameter of
A separator using a mat-like separator made of fine short glass fibers of about 0.2 to 5 μm is in practical use.
It shows excellent performance. However, this type of fine glass fiber is expensive, and batteries using it have the disadvantage of increasing the price of lead-acid batteries. For this reason, various proposals have been made to obtain inexpensive separators. For example, in Japanese Patent Publication No. 42-8402, paper is made by beating glass fibers using hydrated amorphous silicon oxide powder as a paper-making liquid, and after incomplete drying, it is made into an acid-resistant and oxidation-resistant resin suspension or solution. A separator that is soaked, dried, and heat treated has been proposed. However, in this separator, the silicon oxide is fixed with an oxidation-resistant resin, so the silicon oxide does not directly interact with the electrolyte, so it is particularly suitable for so-called sealed lead-acid batteries where the amount of electrolyte is limited. In this case, there is a disadvantage that the liquid dries up. Also, in Japanese Patent Publication No. 47-40733, fiber diameters of 4 to 4
A method in which a microporous layer of fibers is formed on a glass mat by dispersing short pieces of 10μ glass fiber and much thinner mineral fibers in water in appropriate proportions and letting them flow down onto the glass mat. However, in the separator formed in this way, the upper microporous layer peels off from the glass mat and separates into two layers, and the pore size is large and the retention and absorption of the electrolyte are insufficient. It has the following drawbacks. Furthermore, when this separator is used in a sealed lead-acid battery, the electrolyte absorption rate between the microporous layer and the glass mat is extremely different, resulting in uneven distribution of the electrolyte within the battery, resulting in an extremely short battery life. It has a major drawback: Also, Japanese Patent Publication No. 55-29579, Japanese Patent Publication No. 55-30194
Various battery separators mainly made of synthetic fibers and inorganic particles have been proposed in the above publications, but all of them have a porosity that is limited at most in order to be used in lead-acid batteries that have a flowing electrolyte. Approximately 60%
However, it cannot be applied to sealed lead-acid batteries due to the insufficient electrolyte content. The object of the present invention is to provide a sealed lead-acid battery that is inexpensive and has performance comparable to that of conventional batteries using fine glass fibers. Synthetic fibers with multiple types of acid and oxidation resistance 30~
A separator with a porosity of 75% or more composed of 3% by weight and 70 to 97% by weight of an acid-resistant inorganic fine powder,
It is characterized by being placed between a positive electrode plate and a negative electrode plate. In other words, while the conventional separator made of fine short glass fibers in the form of a mat is mainly composed of glass fibers and essentially holds the electrolyte in the voids between the glass fibers, the present invention uses electrolytic solution. It is characterized in that the inorganic fine powder has a liquid retention function, and synthetic fibers are arranged to serve as a support for the inorganic fine powder and to provide strength. Hereinafter, the present invention will be explained in detail based on some examples of the present invention and comparative tests with these and other examples. The length is approximately 10mm and the nominal fiber diameter is
0.5 denier polypropylene fiber, length approximately 5 mm
Polyester fibers with a nominal length of 4 denier and acrylic fibers with a length of approximately 5 mm and a nominal 3 denier are dispersed in water, and silica powder or diatomaceous earth as an inorganic fine powder is dispersed in water and formed into paper using a paper machine. A separator with a thickness of 1.5 mm was obtained under a load of 20 Kg/cm 2 . Table 1 shows the blending ratio (weight ratio to the separator) of the materials constituting the prototype separator, as well as its properties and cost. For comparison, Table 1 also lists the characteristics of a conventional separator made of 100% fine glass fibers with a fiber diameter of 0.5 to 1.0 microns. The cost of each separator is expressed as a ratio when the material price of the conventional one is set as 100.
【表】
また第１図に本発明による隔離体ａの想像拡大
図を示す。該図面において１はポリエステル繊
維、２はシリカ粉末である。
密閉形鉛蓄電池用隔離体として要求される特性
は多孔度が約75％以上、含液量が約２c.c.．
H2SO4／dry Sepa.c.c.以上、最大孔径は約30μ以
下、および引張強度は約１Kg／cm2以上であること
が望ましいことを我々は経験的に知得している。
かかる観点からすると、上述の試験結果より無
機微粉末の隔離体に対する重量比は70〜97％が好
ましく、70％以下では多孔度が小さくまた97％以
上にすると引張強度が低下し、実用上適切ではな
い。
また以上のごとく試作した隔離体ａ〜ｇを用い
てそれぞれ密閉形鉛蓄電池Ａ〜Ｇを試作した。こ
れらの極板はいずれもカルシウム合金を格子体と
したもので、通常の方法で公称容量3.5AHに組立
てた。これを公称容量の2/3放電、130％充電を１
∞とするサイクル寿命試験に供試し、その時の寿
命サイクルと電解液の減液率を測定した。その結
果を第２表に示す。なお電池個数はそれぞれ２個
とした。[Table] Furthermore, FIG. 1 shows an enlarged imaginary view of the separator a according to the present invention. In the drawing, 1 is polyester fiber and 2 is silica powder. The characteristics required for a separator for a sealed lead-acid battery are a porosity of approximately 75% or more and a liquid content of approximately 2 c.c.
We have learned from experience that a maximum pore size of H 2 SO 4 /dry Sepa.cc or greater, a maximum pore size of about 30 μm or less, and a tensile strength of about 1 Kg/cm 2 or greater are desirable. From this point of view, the above-mentioned test results indicate that the weight ratio of the inorganic fine powder to the separator is preferably 70 to 97%; if it is less than 70%, the porosity is small, and if it is more than 97%, the tensile strength is reduced, so it is not suitable for practical use. isn't it. In addition, sealed lead-acid batteries A to G were trial-produced using the separators a to g produced as prototypes as described above. All of these plates were made of calcium alloy as a lattice, and were assembled to a nominal capacity of 3.5AH using the usual method. Discharge this to 2/3 of the nominal capacity and charge it to 130%.
It was subjected to a cycle life test at ∞, and the life cycle and electrolyte reduction rate were measured. The results are shown in Table 2. Note that the number of batteries was two for each.
【表】
第２表から明らかなごとく、合成繊維の量が30
重量％より多い密閉形鉛蓄電池Ｅでは、その寿命
が短かくまた減液率も多かつた。これは一般に合
成繊維と電解液のなじみが悪いことから、電解液
を保持しない空隙が多くなり易く、従つて試験開
始初期に見掛け上保持されていた電解液が寿命試
験中に消失し電解液比重が上つたため正極格子体
の腐蝕が促進され寿命が短かくなつたと考えられ
る。
これに対し合成繊維の量が30重量％より少ない
場合には、隔離体中に適当量の電解液を保持しな
い空隙を生じ、この結果、正極板で発生した酸素
ガスがその空隙を通過して負極板に到達し易くな
り、これにより減液率が少なくなるという効果を
示したものと推察される。なお、電池Ｆは性能が
良いが、第１表に示した如く、隔離体の引張強度
が弱すぎるため、実際の電池生産を考えた場合、
組立ができず実用にならない。
以上のごとく本発明における隔離体では、その
構成材料である合成繊維は隔離体に必要な強度を
与え、かつ上記無機微粉末を支持する役目、さら
には電解液を保持しない空隙を作る役目を果し、
他方、無機微粉末は所望の電解液を保持するとと
もに、正極板と負極板との短絡を防止する役目を
果すものである。
それゆえ合成繊維としては、その形状としてフ
イブリル化されている方が見掛け密度が高くない
点で好ましく、その繊維径は細い方が多孔度が高
くなる点で望ましい。またその長さは約５mm以上
の方が強度が高くなる点で望ましいが、特にその
種類は限定されるものではない。もちろん本発明
の主旨を逸脱しない範囲で製造上の理由などによ
り無機繊維を少量混合してもよい。また無機微粉
末としては、耐酸、耐酸化性を有し、電解液の濡
れ性に優れたものであればよく、その種類は特に
限定されるものではないが、その粒径の小さなも
のは孔径を小さくできるが多孔度を得にくく、逆
に粒径の大きなものもは多孔度は得やすいが孔径
が大きくなる傾向にあるので、0.01μm〜20μmの
適当な粒径のものが混ざつているものが望まし
い。さらに電池性能を損なわない範囲でバインダ
ーを使用してもよい。
また隔離体の製法としては実施例では抄紙法に
よるものを記載したが、これだけに限定されるも
のではない。なお隔離体の生産において、加熱・
加圧加工は強度および孔径の調節の点から適当な
水準で実施してもよいが、過度な加工は多孔度を
減ずることにより、望ましいものではない。しか
し合成繊維の量が少ない場合には無機粒子を結合
する上で加圧をしない状態での加熱は、無機粒子
粉末の固定および隔離体の取扱い性向上の点で好
ましいことが多い。
上述のごとく本発明は合成繊維の配合を隔離体
に対して30重量％以下とし、残部を無機微粉末と
した多孔度75％以上の隔離体を使用することによ
り、安価でかつ従来の微細ガラス繊維を隔離体と
して使用した電池と同様の電池性能を得ることが
できるものであり、その工業的価値は大なるもの
である。[Table] As is clear from Table 2, the amount of synthetic fiber is 30
Sealed lead-acid battery E containing more than 1% by weight had a short life and a high liquid loss rate. This is because synthetic fibers and the electrolyte generally do not fit well, so there are likely to be many voids that do not hold the electrolyte, and the electrolyte that was apparently retained at the beginning of the test disappears during the life test, causing the specific gravity of the electrolyte to decrease. It is thought that this increased corrosion accelerated the corrosion of the positive electrode grid and shortened its life. On the other hand, if the amount of synthetic fibers is less than 30% by weight, there will be voids in the separator that do not hold an adequate amount of electrolyte, and as a result, oxygen gas generated at the positive plate will pass through the voids. It is presumed that this has the effect of making it easier to reach the negative electrode plate, thereby reducing the liquid loss rate. Although Battery F has good performance, as shown in Table 1, the tensile strength of the separator is too weak, so when considering actual battery production,
It cannot be assembled and is of no practical use. As described above, in the separator of the present invention, the synthetic fibers that are its constituent materials provide the separator with the necessary strength, support the inorganic fine powder, and create voids that do not retain the electrolyte. death,
On the other hand, the inorganic fine powder holds the desired electrolyte and also serves to prevent short circuits between the positive electrode plate and the negative electrode plate. Therefore, as a synthetic fiber, it is preferable that the fiber is fibrillated in terms of its apparent density not being high, and it is preferable that the fiber diameter is thinner in terms of increasing the porosity. Further, it is preferable that the length is about 5 mm or more because the strength is increased, but the type thereof is not particularly limited. Of course, a small amount of inorganic fiber may be mixed for manufacturing reasons without departing from the spirit of the present invention. In addition, the inorganic fine powder may have acid resistance, oxidation resistance, and excellent electrolyte wettability, and its type is not particularly limited. Although it is possible to reduce the porosity, it is difficult to obtain porosity, and conversely, it is easy to obtain porosity with large particles, but the pore size tends to increase, so particles with an appropriate particle size of 0.01 μm to 20 μm are mixed. Something is desirable. Furthermore, a binder may be used within a range that does not impair battery performance. In addition, as the method for manufacturing the separator, although a paper-making method is described in the Examples, the method is not limited to this. In addition, in the production of separators, heating and
Pressure processing may be carried out at an appropriate level from the viewpoint of strength and pore size control, but excessive processing is undesirable because it reduces porosity. However, when the amount of synthetic fibers is small, it is often preferable to heat the inorganic particles without applying pressure in order to bond the inorganic particles, from the viewpoint of fixing the inorganic particles and improving the handling of the separator. As mentioned above, the present invention uses a separator with a porosity of 75% or more, in which the synthetic fiber content is 30% by weight or less based on the separator, and the remainder is inorganic fine powder, thereby making it possible to reduce the cost and replace conventional fine glass. It is possible to obtain battery performance similar to that of a battery using fiber as a separator, and its industrial value is great.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は本発明における隔離体の一実施例を示
す想像拡大図である。
１……ポリエステル繊維、２……シリカ粉末。
FIG. 1 is an enlarged imaginary view showing one embodiment of the separator according to the present invention. 1... Polyester fiber, 2... Silica powder.