JPH0650632B2 - Exhaust plug for storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a storage battery exhaust plug having sufficient water repellency, air permeability and strength for practical use.

(Prior Art) A filter that constitutes an exhaust plug of a lead acid battery or the like is required to have breathability, water repellency, and strength. When the storage battery is charged, the electrolytic solution is electrolyzed to generate hydrogen and oxygen. If these gases do not have sufficient air permeability in the filter that separates the inside and outside of the storage battery, they accumulate in the storage battery and cause an explosion, or increase the internal pressure, causing the electrolyte such as strong acid to overflow to the outside, which may damage the battery peripheral equipment. May corrode. Further, if there is no water repellency, the electrolytic solution may overflow to the outside even by weak vibration. Furthermore, a vibration-proof structure of the exhaust plug itself is also required.

Various filters for exhaust plugs have been studied so far in order to satisfy such characteristics. The filters generally used at present are inorganic substances having excellent electrolytic solution resistance and heat resistance, for example, porous bodies such as fused alumina, silicon carbide and silica treated with a silicon-based water repellent. In the exhaust plug using such a filter, the water repellent agent is decomposed due to the decomposition of the water repellent agent by the electrolytic solution scattered by the vibration of the battery. As a result, there arises a problem that the electrolytic solution overflows from the exhaust plug. Further, a method of treating a porous material such as fused alumina with a water-repellent fluororesin resin purgeon has been proposed, but this method cannot coat the fluororesin uniformly inside the pores of the porous material. However, the fluorine resin locally gathered and solidified, possibly closing the hole.
In addition, the other parts were left uncoated and the electrolyte could overflow even with mild vibration. Furthermore, a porous film containing a fluorine resin having water repellency is formed on the end surface of a porous body such as fused alumina (Japanese Patent Laid-Open No. 43-8510), or a ceramic or a synthetic resin porous body provided inside an exhaust plug is used. Which is covered with a gas permeable film made of water-repellent polyfluorinated ethylene or high-density polyethylene (JP-A-61-161655, JP-A-61-116).
1656) has also been proposed.

(Problems to be solved by the invention) However, in the method according to the prior art described above, the gas permeability of the membrane itself is not sufficient, the generated gas stays in the storage battery, or the adhesion strength of the membrane to the porous body is weak, Between the porous body and the porous membrane, peeling or breakage of the membrane is likely to occur, and the electrolytic solution may enter the inside of the porous body to cause clogging, which may damage the storage battery.

The present invention provides sufficient water repellency to prevent the electrolyte from overflowing due to mechanical vibration and the like, and sufficient breathability to discharge gas such as hydrogen generated in the storage battery by electrolysis to the outside. Further, it is a technical object to provide a filter that constitutes an exhaust plug of a storage battery and that has a strength that does not break due to mechanical vibration or the like.

[Structure of Invention]

(Means for Solving the Problems) In order to solve the above-mentioned technical problems, the technical means taken in the invention of claim 1 is that the filter provided inside the exhaust plug for the storage battery is made of an inorganic porous material. A thin film layer composed of a fluorine-based graft polymer is formed on the inner surfaces of a large number of gas-permeable pores of the inorganic porous material, and the fluorine-based graft polymer contains a hydrophilic segment and fluorine. And a hydrophobic segment.

In order to solve the above technical problem, the technical means taken in the invention of claim 2 comprises a fluorine-based graft polymer after the inorganic porous material is dipped in a silane coupling agent or a titanium coupling agent. That is, a thin film layer is formed.

(Function) The present invention is technically characterized in that the surface of a large number of pores through which a gas of a porous body made of fused alumina, silicon carbide or the like having an electrolytic solution resistance and the like passes is uniformly coated with a fluorine-based graft polymer film. .

The fluorine-based graft polymer film is composed of a hydrophilic segment and a hydrophobic segment containing fluorine. When the porous body is impregnated with the polymer solution, the hydrophilic segment moves to the pore interface of the porous body, which is a hydrophilic surface, and the polymer is bonded to the porous body by the Van der Waals force. The hydrophobic segment migrates to the hydrophobic surface (air surface). Therefore, the inner surfaces of all pores of the porous body are uniformly covered with a thin film made of the polymer. As described above, according to the present invention, the surface of the pores of the porous body can be easily rendered water repellent.

(Examples) Hereinafter, preferred examples using the technical means of the present invention will be described together with experimental examples.

The present invention is an inorganic porous material such as fused alumina and a large number of pore surfaces for passing gas formed in the inorganic porous material, the membrane or inner layer made of a fluorine-based graft polymer is made of a silane coupling agent or a titanium coupling agent. The present invention relates to a storage battery stopper filter, characterized in that the outer layer is a film made of a fluorine-based graft polymer, and a method for producing such a filter.

The porous material used in the present invention is prepared by mixing a binder such as glass powder with an inorganic substance excellent in electrolytic solution resistance, heat resistance, etc., such as fused alumina, silicon carbide, silica, glass fiber, glass powder, graphite or carbon at high temperature. It is heated. The porous body may have sufficient air permeability to exhaust gas such as hydrogen generated in the battery, and may be used for a filter of a storage battery exhaust plug.

Examples of the silane coupling agent include vinyltriethoxysilane, γ-methacryloxy-propyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-
There are β- (aminoethyl) -γ-aminopropyl-trimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxy-propyltrimethoxysilane and the like, which are used as a primer. But good.

Further, as the titanium coupling agent, dihydroxy
Bis (lactato) titanium, di-η-butoxy bis (triethanolaminato) titanium, i-propoxytitanium-tri-i stearate, tetrakis (2-ethylhexoxy) titanium, tetra-η-butoxytitanium, and tetra- There is i-propoxy titanium and the like.

These silane coupling agents and the like are usually used by dissolving them in water or water and alcohol. The concentration of the silane coupling agent or the like is in the range of 0.1-100%, preferably 0.5-3%. If the concentration is less than 0.1%, the film of the silane coupling agent or the like formed is thin, and even if a fluorine resin film is coated on this, sufficient adhesion cannot be obtained. The coating of a film of a silane coupling agent or the like is performed by immersing the porous body in the above solution, sufficiently impregnating the inside of the pores with the solution, and then pulling it up and air-drying. Thereafter, in order to strongly react the silane coupling with the porous body, the silane coupling is heated at 100 to 120 ° C. for 5 to 120 minutes.

[Experimental example]

Hereinafter, description will be made based on experiments actually performed by the inventors.

(Experimental example 1) 15 wt% of glass powder was added to spherical alumina particles (# 50).
Mix and mold into a predetermined shape of 11.5φ x t4.0.
Next, a ceramic porous body is produced by heating to 1400 ° C. in an air atmosphere. Fluorocoat EC-10, which is a fluorocarbon coating agent, for the prepared ceramic porous body
4 (made by Asahi Glass). After taking it out from the fluorine coating agent, it is baked at 200 ° C. for 1 hour.

(Experimental Example 2) The ceramic porous body produced in Experimental Example 1 is immersed in a 2% solution of γ-glycidoxy-propyltrimethoxysilane. Then, after heat treatment at 200 ° C. for 1 hour, it is immersed in the fluorocarbon coating agent Fluorocoat EC-104 as in Experimental Example 1. 20 after removing from fluorine coating agent
Bake at 0 ° C for 1 hour.

Experimental Example 3 Instead of γ-glycidoxy-propyltrimethoxysilane used in Experimental Example 2, N-β- (aminoethyl)-
A sample was prepared by surface-treating with γ-aminopropyl-trimethoxysilane in the same process.

Experimental Example 4 Instead of γ-glycidoxy-propyltrimethoxysilane in Experimental Example 2, tetrakis (2-ethylhexoxy) was used.
A sample was prepared by performing surface treatment using titanium in the same process.

(Comparative Example) The comparative example used was a filter for a storage battery in which a ceramic porous body composed of mullite particles was subjected to a water repellent treatment with dimethylpolysiloxane which is a silicone water repellent.

(Test method) In order to investigate the electrolytic solution resistance of each filter of the above-mentioned Experimental Examples 1 to 4 and Comparative Example, it was immersed in 37% sulfuric acid at 80 degrees for 720 hours and washed with water, and then each filter was attached to the battery. Table 1 shows the results of the measurement of electrolyte leakage after the vehicle was mounted on a passenger car and run on a rough road test course (to ensure that the storage battery is loaded with sufficient vibration) for 1 hour.

In each of the experimental examples, sufficient leakage resistance was exhibited after the acid resistance test, but in the comparative example, leakage occurred. It is speculated that this is due to the difference in the chemical resistance of the coated layers.

〔The invention's effect〕

The exhaust plug obtained according to the present invention has a uniform and thin coating of a fluorine-based graft polymer having water repellency on the surface of the pores of the porous body which is a filter, so that the phenomenon of clogging of the pores is unreliable and the breathability is high. Sufficiently enough to allow the gas generated in the battery to escape to the outside almost completely.

In addition, since the fluorine-based graft polymer is firmly attached to the porous body through its hydrophilic segment, it does not peel off due to mechanical vibration, etc., and can maintain its water repellency for a long period of time. It is possible to prevent electrolyte leakage.

Further, in the exhaust plug according to the present invention, the fluorine-based graft polymer film is thinly coated on the surface of the pores of the porous body, and the strength is maintained by the porous body, so that sufficient strength is ensured for practical use. The fluorine-based graft polymer film is excellent in electrolytic solution resistance and does not decompose by sulfuric acid, which is an electrolytic solution, unlike the silicon-based resin film currently generally used.

If the surface of the pores of the porous body is previously coated with a film of a silane coupling agent or the like using a solution of a silane coupling agent or a titanium coupling agent, the adhesion strength of the fluorine-based graft polymer to the inner surface of the pores can be further enhanced. it can. Silane coupling agents, etc., have two or more different reactive groups introduced into their molecules. One of them is a reactive group that covalently bonds with porous ceramics etc. to form a strong bond. , And others are reactive groups that bond with the fluorine-based graft polymer. The bond between the silane coupling agent and the fluorine-based graft polymer is due to both the bond due to the van der Waals force and the covalent bond, and the bond is stronger than when the porous body is directly coated with the fluorine-based graft polymer film. Is.

As described above, by using the technical means of the present invention, it is possible to provide a storage battery filter having excellent liquid leakage.

Claims (2)

[Claims] 1. A filter provided inside an exhaust plug for a storage battery is made of an inorganic porous material, and a thin film layer made of a fluorine-based graft polymer is formed on the inner surfaces of a large number of gas-permeable holes of the inorganic porous material. The exhaust plug for a storage battery, wherein the fluorine-based graft polymer has a hydrophilic segment and a hydrophobic segment containing fluorine. 2. An exhaust plug for a storage battery according to claim 1, wherein the inorganic porous body is dipped in a silane coupling agent or a titanium coupling agent and then a thin film layer made of the fluorine-based graft polymer is formed.