JPS60117540A - Galvanic cell and seal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to sealed galvanic cells, such as primary alkaline cells, and specifically to sealed insulating members (hereinafter referred to as seals) used in such cells. The seal is formed by filling a thermoplastic resin material such as polypropylene with minerals such as talc, calcium carbonate, or minerals.

BACKGROUND OF THE INVENTION The common construction of sealed cylindrical galvanic cells is to load the main components into a can and seal the cell by providing a seal at the open end of the can. The seal prevents electrolyte from returning from the battery and prevents contact between the battery electrodes, insulating them from each other.

The seal reduces the pressure built up inside the battery, and also prevents the loss of moisture and the intrusion of oxygen or carbon dioxide into the battery.
It is desirable to be able to pass the light through. Historically, a seal has a 11 wall portion to serve as a vent for the rupturable thin film, and by making the thickness smaller than the thickness of the material surrounding the thin film, the gas flow inside the battery is reduced. When the temperature rises, the battery is heated to 1m to prevent the battery from exploding.

DETAILED DESCRIPTION The seal according to the invention is used in a cylindrical sealed battery, and the seal is made of thermoplastic Q'll which is inert to the electrolyte.
They are made from polypropylene materials, such as polypropylene, polyethylene (particularly polysulfone for high-temperature applications), and their co-merchandising materials, generally by molding. The thermoplastic material contains 5 to 4.5% by weight of a mineral filler, and the mineral is talc [theoretically, Mg3Sin,o(OH)].
2)), consists of calcium carbonate and my power! It is selected from I-cho. Depending on the purpose for which the seal is used, it is decided whether or not it should be annealed. When polyprene is annealed, it is carried out at a temperature of 70 DEG C. to 155 DEG C. (other suitable temperatures are provided for other thermoplastic materials such as copolymers of polypropylene and polyethylene). The annealing process is preferably carried out in an air circulating oven or tunnel. In many cases, mineral-filled polypropylene seals and how to place them inside the battery are often used. Regarding whether to do so, please refer to the pending patent application No. 57-235131 and Tokuho No. 58-1.
08518.

Plastic parts made by injection molding of talc-loaded polypropylene do not exhibit sink marks such as dents or irregularities on the surface. This is particularly important when forming seals with thin films. Since this part can be molded without causing sink marks, the molding tolerances and conditions during part molding are not uniform.

Mineral fillers such as talc can lower the molding temperature. In addition, mineral fillers such as taru are heat riJ'
Since it adds 4F glare to the surface of the jpJ material, it can act as a mold release agent for the inner mold. This property is particularly useful since release agents in the outer mold, such as silicone, can contaminate the molded part and this contamination can generate gas within the cell. Mineral fillers (talc, calcium carbonate or mica)
Do not generate gas inside ylh. Silk retention after molding is small, especially when the concentration of the filler is high, for example in the ψi range of 20 to 40% in the case of talc, and the molding of the seal insulation member can be carried out more precisely.

Finally, the cost per unit of mineral-filled plastics is less than that of non-mineral-filled plastics.

The inventors have discovered that substantial mechanical advantages can be obtained by using filled thermoplastic materials. These include "J1" which improves the sealing and venting properties of the component.

The filled thermoplastic material has a small coefficient of linear expansion, and is very close to the coefficient of linear expansion I of a metal can used in a battery device. The sealing condition is therefore improved, especially after being subjected to thermal cycling. Filled thermoplastic materials have a higher compressive strength than unfilled materials, resulting in an improved crimp seal.

This can be further enhanced by annealing the sole insulation member. The annealing process stabilizes the dimensions of the seal insulation member, ie, the physical dimensions of the part remain constant. The annealing process can also relieve the -03 molding stress generated during the molding process.

Since the filler acts as a stress concentration means, even a slight deflection of the thin film can cause ventilation or breakage of the thin film. When a filled seal is annealed, the stress generated during forming is released, and the increase in the breaking pressure of the thin film is less than that when annealing is performed without loading the filler.
This is relatively smaller than the increase in the breaking pressure of the lj membrane. By annealing the filled material, it is possible to know with greater certainty what the breaking strength of the thin film is.

Similarly, by deploying a thermoplastic material with a filler, the spread due to rupture of the membrane is smaller than with a mature plastic abrasive material without a filler, and excessive pressure builds up within the 7142. tS, the space required for the 1-part space can be reduced.

By molding the i'2j7 film thicker,
While the tolerances of the ventilation mechanism are maintained within a predetermined range, the molding tolerances can be made wider.

Historically, the space required to rupture the vent can be less, and the seal can be placed a little higher on the can, allowing more of the activator to flow through the battery. It can be loaded inside.

Since the filled thermoplastic abrasive material of the present invention is permeable to hydrogen, a battery loaded with a sealing member is gradually ventilated. This gradual venting allows sufficient hydrogen to escape from the pond, thereby reducing the chance of battery venting or membrane rupture.

Especially in the case of alkaline city ponds, 1F is necessary because it can considerably reduce the corrosion of mercury and the release of the scum inhibitor component that must be loaded into the battery, making it more environmentally friendly. It is not only possible to obtain a good product, but the working conditions of battery assembly are improved, and costs can be reduced.

When exposed to an electrolyte, for example a 40% potassium hydroxide solution, filled thermoplastic materials have the advantage of being much less susceptible to porosity than glass-filled nylons used as battery seals.

That is, polypropylene filled with talc, calcium carbonate, or minerals does not decompose like glass-filled nylon when exposed to KOH at 71° C. for as long as four weeks.

The term "thermoplastic material containing a filler" as used herein refers to a material containing 5 to 45%, usually 15 to 40%, of a filler such as talc, calcium carbonate, or mineral filler, and the filler material is in the form of a very fine powder. or fine granular substances. Furthermore, because the filler material is internal to the molded thermoplastic seal insulation member, there is little exposed surface of the filler material in the molded part. In this regard, when using talc as a filler, approximately 20%, but up to 4%
It is desirable to use 0% talc as a filler, especially in polypropylene.

2, the annealing treatment has the advantage of removing the stress generated during molding and stabilizing the physical dimensions of the seal insulating member after molding. However, even if the seal is not annealed, it can still exhibit superior performance compared to a similarly structured product without filler. This is a thin film of seal insulation material +! This is because it is possible to widen the manufacturing tolerance by 1i, which allows the molding to be made thicker, and it is possible to estimate the shearing pressure more accurately. In either case, the rupture pressure is somewhat high, but the pressure reached is not enough to cause the cathode container to become undone, dislodging the entire chamber and damaging the cell.

Typical analytical values for talc-filled polypropylene are as follows. The melt index of the unfilled polypropylene resin was 10 to 15, but the melt index after filling was reduced to about 6 to 10.

Talc is a white powdery material in the form of plates or small plates, does not contain asbestos, and its chemical composition is within the following ranges:

Ingredient % weight MgO20-3'2% Sin216-46% CaO9-30% Al2030.5-4% Fe,,o30.2-4% LOI (loss on ignition) 8-20% Note: Loss on ignition is talc represents the percentage of carbon dioxide removed by heating.

A typical distribution of particle sizes is within the following ranges:

Passing mesh size %Tri. 44 micron 100% 30 micron 94-97% 20 micron 75-90% 10 micron 40-60% 5 micron 1B-32% 4 micron 14. -24% 3 microns 9-17% 2 microns 75-10% 1 micron 4-4% Typical values for drybrightness are 84-94. Tap density is 60-80 bonds/cubic foot. Loose density is 24-55 pounds per cubic foot. The ratio II is 2.8-29. The amount of music absorbed by Talc 1009+ is 20-35
F! It is. , H is 9 to 105. Hegman fineness is 1-35. 1 passes through 200 meshes
00%, those passing through 325 mesh are 98-999
%.

Similarly, calcite (carbonate, runum) is shown as &(7).

1, Common % weight CaC039598% MgCO31-2% A! 2030.05-0.2% pe2030.01-0.2% SiO20.1-1% MnO0.01% No copper detected, moisture 0.25% Organic coating 05-2% (typically silane) Typical The particle size is smaller than 15 microns (spherical particles) (100%, 95-99% smaller than 10 microns, 75-8% smaller than 5 microns)
5%, 40-60% smaller than 25 microns,
20-40% of the particles are smaller than 1 micron. The average particle size is on the order of 2.5 microns, with a specific gravity of about 2.7 and a refractive index of about 1.55.

Some examples are shown below.

Several AA size seals (lids) were molded from nylon, unfilled polypropylene and polypropylene with 20% talc filler. Half of each polypropylene seal was annealed and the other half was not annealed. All seals were completely contained within the cell and crimp sealed, except that the outer jacket was not attached to the cell. After performing various storage and use tests, leakage was observed.

The results of the leakage test were as follows. After one week of storage at high temperature and another week of stabilization at room temperature, annealed lids and nylon lids are virtually leak-free (30
(1 out of 5) points were the same. However, a significant number of lids that were not annealed leaked.

The other lids were left at a temperature slightly lower than the above temperature, but still quite high for two weeks, and then stabilized at room temperature for an additional week, resulting in one nylon lid. One lid without filler leaked and the lid with filler did not leak.

Furthermore, as a result of storing other lids at extremely low temperatures for one week and stabilizing them at room temperature for another week, the nylon lids were
The annealed filled lids performed much better, with only 1 out of 30 leaking, compared to 20 out of 30 leaking.

Similarly, when another group was subjected to repeated temperature cycles from low to relatively high temperatures and then stabilized at room temperature, 15 out of 30 nylon lids leaked. In contrast, only 2 out of 30 annealed filled rusts leaked.

All cells were vented after storage for one day at room temperature for the other samples and then applying a current of 1.5 amps. The other lid was stored at elevated temperature for several days before a 1.5 amp current was applied. Three out of three of the annealed filler-containing polypropylene pieces showed a common problem, but one out of three of the 'ichiike' pieces with a nylon lid showed extremely severe fracture.

Example 2 Several AA1G and D type battery lids were molded, all with breakable venting membranes ranging in thickness from 0.0035 to 0.005 inches. Samples include one without talc filler, one with 20% talc filler, and one with talc filler, 0
% filler was molded.

Some lids were selected as controls and were not immersed in the potassium hydroxide solution. The other groups of lids were immersed in potassium hydroxide solution for 2 weeks at room temperature, 2 weeks at high temperature, or 2 weeks at very high temperature. Next, a ventilation test was conducted outside the battery. All of the lids that were soaked and stored in KOH had fairly consistent venting results when compared to the control group that was not soaked in KOH. In other words, all samples were chemically resistant to KOH solution.

The conclusions drawn from these ventilation test results are city requirements f. The reason is that the thin film part of the filled polypropylene lid, i.e. the vent pressure relief part, is not affected by the high temperature anolekali electrolyte, and therefore is not affected before or after long-term storage at high temperatures. At the same pressure, the membrane will rupture and the battery will be vented.

Example 3 A further ventilation test was conducted as follows. A ventilation film having a thickness of 0.0055 inch was formed on the lid, and tests were conducted by varying the clearance above the film. An unfilled polypropylene lid did not vent, but small clearances and very high pressures did.

On the other hand, the lid filled with 20% talc was vented at a reasonable pressure. At a clearance of 0.091 inches, the unfilled, unannealed polypropylene lid did not vent at a pressure of 850 pSl. However, using the same lid with a clearance of 0.145 inches vented at 280 psi. Talc 2
0% filled, unannealed polypropylene lids were vented at 480 psi for the smallest clearance and 280 psi for the largest clearance. . On the other hand, a polypropylene lid filled with 20% talc and annealed has a minimum clearance of 42
0psi, 400ps for maximum clearance
Aeration was performed at i.

Example 1 Glass-filled nylon, unfilled propylene,
20% talc filled polypropylene and 40% talc filled polypropylene lids were molded and then KQI
{Stored in electrolyte at 71°C for 1 month. After storage, the solution was acidified and analyzed for trace amounts of metal elements. With the exception of the fact that the amount of calcium filtered through a polypropylene lid filled with 20% talc is slightly higher, polypropylene lids do not contain nickel, cadmium, strontium, cobalt, titanium, molybdenum, lead, copper, iron, No significant differences were observed among filter caps made of vanadium, chromium, aluminum, silicon, or calcium. On the other hand, in the case of glass-filled nylon, considerable amounts of titanium, copper, iron, vanadium, aluminum, silicon, and calcium were filtered out.

The filled thermoplastic seal of the present invention may be of any shape, which is beyond the scope of the present invention. However, designers can use greater tolerances during molding and design the rupturable vent membrane to be thicker and still achieve the same performance as batteries currently in use.

The scope of the invention as described herein is defined by the claims.

Claims (1)

[Claims] ■ A sealing member used in a crimp-sealed galvanic cell, which is formed from a thermoplastic material containing 5 to 45 weight percent of a filler, and the thermoplastic material and filler are used in a sealed battery. A galvanic device which is chemically inert to the electrolyte material used, has a breakable vent in the member, and has a wall thickness smaller than the wall thickness surrounding the vent. Battery sticker. ■The thermoplastic material is selected from the group consisting of polypropylene, polyethylene and their copolymer, and the filler is talc,
A seal according to claim 1 selected from the group consisting of calcium carbonate and calcium carbonate. 2. A seal according to claim 2, wherein the thermocifql material is made of polypropylene containing talc filler. (2) The seal according to claim 3, wherein the content of talc is 15 to 40%. ■The seal described in Claim 1, ζ, in which the seal is annealed. (2) The sole according to claim 4, wherein the annealing temperature is within the range of 70 to 155°C. (2) The seal according to claim 4, wherein the annealing treatment is carried out at 70 to 155° C. for one hour or more. ■The particle size of talc is smaller than 44 microns in maximum dimension, and more than 1% of double printing is smaller than 1 micron.
ffi % 1 is larger than 5 microns, 40fi
5. A seal according to claim 4, wherein the seal is greater than 10 microns. (2) It is formed from a thermoplastic material containing 5 to 45% filler by weight, and the filler and the thermoplastic material are each chemically inert to the electrolyte H material used in sealed batteries; A galvanic cell characterized in that a container is talimp-sealed using a sealing member that forms a breakable vent and has a wall thickness smaller than that surrounding the vent.