MXPA98009038A - Bater separator - Google Patents

Abstract

The present invention relates to a battery separator for use in flooded cell-type lead-acid batteries comprising a continuous backing tape of a porous, high-porous resistant material with a plurality of ribs extending from at least one surface flat of the continuous backup tape. The ribs are positioned across the front of the continuous backing tape and extend in a direction substantially parallel to the longitudinal dimension of the continuous backing tape. Each rib is an enhanced corrugated structure comprising alternate ridges and grooves. The edges and grooves are in alignment not parallel with respect to the longitudinal dimension and separator, and preferably perpendicular to it. The ribs are formed in a continuous strip separating batteries, essentially flat by passing the continuous backing tape through the attachment point formed by a pair of roller to enhance opuest

Description

BATTERY VIEWER ' BACKGROUND OF THE INVENTION This invention relates to a battery separator for use in lead acid batteries of the flooded cell type and to a method and apparatus for manufacturing the separator. In the flooded cell type lead acid battery, the positive and negative electrodes or "plates" are separated by a battery separator. The battery separator typically has "ribs" or protuberances extending from at least one flat face of the separator. These ribs are formed in one of several ways: the ribs can be formed integrally with the continuous backing tape of the spacer; the ribs can subsequently be applied to the continuous backing tape as a flange of a material equal to or different from the continuous backing tape, or the ribs can be formed by embossing the continuous backing tape. The ribs function to provide proper separation between the plates and to provide a space where the free electrolyte is left. The battery separator currently used by most manufacturers of lead acid batteries of flooded cell type is a type of microporous polyethylene. This type of separator has a composition consisting essentially of an ultra high molecular weight polyethylene, a filler or filler (typically amorphous silica), a plasticizer (typically a processing oil), and certain secondary ingredients such as an antioxidant, a lubricant and carbon black. The material of the microporous polyethylene separator is commercially manufactured by passing the ingredients through a heated extrusion apparatus, passing the extruded material generated by the extrusion apparatus through a die and towards the clamping point formed by two calendering cylinders. heated to form a continuous belt, extracting a considerable amount of the processing oil from the continuous belt by the use of a solvent, drying the extracted continuous belt, cutting the strip into strips of predetermined width in strips, and winding the bands into rolls . These separators and the method of manufacturing thereof are described in U.S. Patent Number 3,351,495. Microporous polyethylene separators typically have a configuration comprising a continuous backing tape having a predetermined thickness, and a plurality of parallel ribs spaced apart at a predetermined distance and extending outwardly from a flat surface of the continuous backing tape. The ribs extend continuously in a longitudinal direction parallel to the edges of the spacer material. A partial perspective view of this prior art separator is illustrated in Figure 7. The thickness of the continuous tape of the backrest at the height and spacing of the ribs specific to the spacer manufacturer by the battery manufacturer; the specifications are designed to maximize certain battery characteristics desired by the battery manufacturer. These ribs are formed by the manufacture of the microporous polyethylene separator by providing a way for one of the two heated calendering cylinders forming the clamping point through which the extruded material is fed from the extrusion apparatus to be engraved with slots. so that the ribs are formed as an integral part of the continuous separating tape. Many different specifications are required by the battery manufacturers in relation to the size of the rib and the separation of the rib. In the manufacture of the separator material to meet the requirements of the customer, almost every change in the size and separation of the rib, requires the separator manufacturer to paralyze its manufacturing line in order to remove the engraved cylinder that is being used to fill the order above and insert a differently shaped engraved cylinder capable of producing the size and spacing of the rib required by the new order to be stocked. The manufacturing time is lost during this shutdown and extra waste material is generated during the start of the line. further, the ribs formed integrally in the polyethylene type separator undergoes extraction along with the continuous backing tape and because it has relatively more volume than a portion of the continuous backing tape occupying the same flat surface area, in general, the ribs retain more processing oil than the continuous backing tape, thus raising the total electrical resistance of the separator. An object of this invention is to provide a separator having a new type of rib formed therein which occupies less volume of the separator but which provides at least good separation capability between the plates as the ribs of the prior art. A further object of this invention is to provide a battery separator having a rib configuration that is capable of forming in the separator subsequent to the formation of the continuous backing belt. A further object of this invention is to provide a simple method and apparatus for forming the ribs in these spacers.

COMPENDIUM OF THE INVENTION This invention relates to a battery separator having a longitudinal dimension, a width dimension perpendicular to the longitudinal dimension, upper and lower planar faces and a plurality of ribs (at least three) projecting from at least one side flat, the ribs extending in a direction essentially parallel to the longitudinal dimension of the separator, each of the ribs being formed of a plurality of enhancements projecting individually forming a corrugated structure comprising alternate ridges and grooves.

It is preferred that the ribs extend from both flat sides of the spacer. In this preferred mode, the projecting shoulders (edges) on a flat face are separated by an indentation (groove) that forms a projecting enhancement (edge) on the other flat face of the separator. When the ribs extend from both planar faces of the spacer the ribs projecting from a flat surface may have a height equal to or different from the height of the ribs extending from the other planar surface. This invention also relates to a method and apparatus for forming ribs in the essentially flat spacer web having a longitudinal dimension, a width dimension perpendicular to the longitudinal dimension and upper and lower flat faces passing an essentially continuous ribbon of this material between a plurality of sets of aligned highlighting wheels, each one. One of the aligned sets of aligned wheels that form a single rib, the adjacent sets of wheels being separated by the desired distance between the ribs, each of the sets of aligned highlighting wheels form a plurality of enhancements in the continuous belt of the wheel. separating material in the longitudinal direction of the continuous belt.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial perspective view of the upper planar surface of the spacer material of this invention. Figure 2 is an enlarged cross-sectional partial-sectional view of the separator taken along line 2-2 of Figure 1. Figure 3 is an enlarged partial-sectional cross-sectional view of a separating rib that is taken on line 3-3 of Figure 1. Figure 4 is an enlarged partial top plan view of a single rib of the invention. Figure 5 is a front view of two highlighting rollers employing a plurality of highlighting wheels. Figure 6 is a side view of two adjacent embossing wheels. Figure 7 is a perspective view of a portion of a prior art separator showing the continuous backing tape and the separator of ribs formed integrally showing the continuous backing tape and the ribs formed integrally extending from the tape continuous backup. Figures 8 to 11 are partial top plan views of the upper flat surface of the separator, illustrating several alternative configurations for the configuration of the rib.

DESCRIPTION OF THE PREFERRED MODALITIES Figure 1 is a partial top perspective view of the separator 10 of this invention. Projecting from the upper flat surface 12 of the separator 10, there are a plurality of ribs 14a to 14j. The ribs 14 are placed in the longitudinal direction of the separator 10, essentially parallel to the longitudinal edges 16 and 18 thereof. Figure 12 is a partial cross-sectional view of the separator 10 taken along the line 2-2 of Figure 1. The rib 14 is above the upper planar surface 12 of the continuous back-up tape 20 of the separator 10. Projecting below the bottom flat surface 13 of the continuous backing tape 20 is a rib 15. The ribs 14 and 15 are identical in width and remain in the same vertical plane. A partial edge view in cross section of the ribs 14 and 15 are illustrated in FIG.

Figure 3. As can be seen, the rib 14 is a corrugated structure comprising alternate edges and grooves 22a and 23a, 22b and 23b, 22c and 23c, 22d and 23d, etc., respectively. Also, the rib 15 is a corrugated structure consisting of alternative ridges and grooves 24a and 25a, 24b and 25b, 24c and 25c, 24d and 25d, etc., respectively. An edge on a flat surface forms a groove on the other flat surface and vice versa. For example, the underside of the edge 22a of the rib 14 forms the groove 25a of the rib 15. Figure 4 is an enlarged partial top view of a rib 14. As can be seen, the ridges 22 and grooves 23 of the rib 14 are perpendicular to the longitudinal side walls 26 and 28 of the rib 14 and therefore, they are also perpendicular to the lateral edges 16 and 18 placed longitudinally of the separator 10. The length dimension of the edges 22 and 24, is In other words, the length of the edges 22 and 24 from one side wall 26 to the other side wall 28 of the rib 14 is selected in accordance with the desired width of the rib. This dimension will generally be between .254 millimeters to approximately 2.54 millimeters. The distance between the adjacent ribs will usually be between about 6.35 millimeters to about 25.4 millimeters. The width of the separator of this invention can be of any width used by battery manufacturers; usually this width will vary from approximately 5.08 centimeters to approximately 30.48 centimeters. The thickness of the back-up continuous tape 20 of the separator 10 will typically be between about .0508 millimeters and about .635 millimeters. The cross section of the corrugated structure forming the rib of this invention is illustrated in Figures 1 to 4, as being triangular, with each individual raised projection being thus wedge-shaped. Each wedge-shaped enhancement comprises an inclined front wall 17, an inclined rear wall 19 and vertical side walls 26 and 28. However, other similar wedge shapes may be used, including but not limited to a rounded wedge shape wherein the view is slightly rounded rather than angular, or a flat wedge shape where the edge is formed either flat during the enhancement or edge is flattened by subsequent pressing. One of the advantages obtained by using the separator of the present invention is that, since the ribs are of corrugated structure formed of adjacent ridges and grooves, the separator provides an environment essentially free of barrier to the flow of the electrolyte and any of the gases released during - Il ¬ the loading and unloading, since the ribs come into contact with the plates only in the area of the edge. The ribs of the prior art (see for example, Figure 7) being solid or solid, are in contact with the positive plate throughout the upper surface area of the rib that imposes a barrier to the flow of the electrolyte and / or gas. An additional advantage obtained by using the separator of the present invention is to reduce or eliminate bending and / or flattening of the rib. When assembling a battery, the number of alternative plates wrapped (with the separator material) and unwrapped required to form a cell are stacked together, compressed and inserted into a cell compartment of a battery case. The compression forces to which the spacers are subjected may cause bending and / or flattening of the undesirable rib in the conventional rib construction, especially larger "total" dimensions, i.e. heights of the rib. The configuration of the rib of the present invention reduces or eliminates this bending and / or flattening of the rib. Even though the separator of the invention is illustrated as having ribs 14 and 15 extending from both flat surfaces 12 and 13 of the continuous backing tape 20, the invention is intended to include a separator wherein the ribs are formed on only one side. Similarly, even when the ribs 14 and 15 are illustrated as having the same height above the flat surfaces 12 and 13, respectively, of the continuous backing tape 20, the height of the ribs on one side may be greater or greater. smaller than the height of the ribs on the other side. In addition, the adjacent edges of a rib may vary in height. Figures 5 and 6 illustrate an apparatus suitable for manufacturing the separators of this invention. Figure 5 is a front view of two embossing or embossing cylinders 30 and 32 having a plurality of embossing wheels 31a-31g and 33a-33g, respectively, placed thereon. Each of the highlighting wheels 31a-31g in the embossing cylinder 30 are aligned with the respectively enhancing wheels 33a-33g in the embossing cylinder 32. Each of the wheels 31 and 33 to be raised are essentially gear wheels with a plurality of gear teeth 32 and 33 respectively projecting therefrom, as best seen in Figure 6. The phrase "highlight wheels" is intended for include both separate gear wheels placed in a highlight cylinder or shaft (such as an accessory of the - - press) or an embossing cylinder having multiple rows of teeth carved into it. The cylinders and / or boosters 32 are rotated by appropriate driving means, not shown. It is preferred that only one of the boosting cylinders 30 or 32 be driven by external driving means with the other cylinder being rotated by the driven boosting roller. The gear teeth 32 and 34 of aligned wheels 31 and 33 intertwine and enhance the ribs 14 and 15 in the flat spacer material 20 when passed through the fastening point between the revolving cylinders 30 and 32. in the direction indicated by the arrow in Figure 6. When the height of the ribs that extend from both flat sides are equal, the teeth 32 and 34 are of equal height. When the height of the ribs on one side is different from the height of the ribs on the other side, the height of the gear teeth 32 and 34 are correspondingly different in height. When it is desired for the ribs to extend from only one surface of the spacer, one of the highlighting wheels 31 or 33 may be a "male" cylinder having gear teeth as illustrated, with the other highlighting wheel being a cylinder " female "having grooves in it with dimensions corresponding to the dimensions of the gear teeth extending from the male cylinder. When it is desired that there be a rib where the adjacent ridges have different heights above the adjacent flat surface of the continuous spacer belt of the spacer, this can be achieved by using as the first cylinder to enhance a male cylinder with gear teeth of variable height as the second cylinder to be enhanced, a smooth cylinder formed of rubber or other deformable material. The formation of the ribs of the present invention involves the plastic deformation of the material of the continuous backing tape at the site where the embossing is carried out. The permanent deformation indicates that the material was loaded beyond its elastic limit which by definition means that it has undergone plastic flow. It has been shown that the oxidation resistance in the area of plastic deformation is improved because the oil is driven towards the surface during the crushing of the micropores. Figure 7 is a perspective view of the separator 40 of the prior art having a plurality of ribs 42 extending from the upper flat face 44 of the continuous backing tape 46. The ribs 42 are integral with the continuous backing tape. 46 and are formed during calendering of the extruded material as described above in discussing the background material. In the preferred mode for practicing the present invention, the continuous ribbon on which the ribs are formed is flat on both sides, and constitutes the continuous backing tape 20 of the finished spacer 10. However, it is intended to include within the definition of "flat" or "essentially flat" (as used herein) a continuous tape having some secondary ribs formed therein during the calendering phase of its manufacture. Although the invention has been described with respect to forming ribs in a microporous polyethylene separator, since this is the main type of separator currently used by manufacturers of lead acid batteries of the flooded cell type, use any separating material that is porous, acid resistant and capable of permanent enhancement. These materials are generally characterized as being loaded or uncharged with continuous non-woven films and tapes of thermoplastic or thermosetting polymers. Suitable thermoplastic polymers include polymers and copolymers of ethylene, propylene, butylene, vinyl chloride and styrene. Suitable thermosetting compositions include phenolic, ethylene / propylene / diene, isoprene, butadiene, styrene and similar thermosetting polymers. The ribs have been illustrated in the preferred embodiment disclosed herein as having ridges and grooves that are aligned perpendicularly with the longitudinal dimension of the spacer. However, the alignment of the ridges and grooves may be such as to form an angle with respect to the longitudinal dimension of the spacer, this angle being less than 180 degrees, and preferably less than about 160 degrees with respect to the dimension longitudinal, but greater than 0 degrees and preferably greater than approximately 20 degrees. In addition, the alignment of the edges and grooves of some ribs with respect to the longitudinal dimension of the spacer may vary from the alignment of the ridges and grooves of the other ribs. Examples of these alternative configurations are illustrated in Figures 8 to 11. Figure 8 illustrates a spacer 100 in which the ribs 114 have raised ribs 114a, 114b and 114c, whose ridges 122 and 124 and the corresponding grooves remain at an angle alternately one with respect to the other. Figure 9 illustrates a spacer 200 in which the rib edges 214 form a chevron pattern constituted of the edge elements 222 and 224. Figure 10 illustrates a spacer 300 in which the rib edges 314 form a pattern. of tractor tread made up of edge elements 322 and 324. Figure 11 illustrates a spacer 400 in which the rib edges 414 form a continuous sinusoidal (zig-zag) pattern consisting of the edge elements 422 and 424. The continuous sinusoidal pattern of the edges could be rounded off in the form of "S") instead of being sharpened as illustrated in Figure 11. A major advantage of the present invention is that it allows manufacturers of the battery separator to continuously produce an essentially flat sheet of microporous material without interrupting the manufacturing process for change engraved calender cylinders. This flat sheet could then be supplied to the manufacturer of the battery in rolls of appropriate width and the manufacturer of the batteries would apply the ribs in accordance with this invention. It is proposed that these ribs be applied just before the wrapping operation of the plate.

Claims (17)

R E I V I N D I C A C IO N E S:

1. A battery separator comprising a continuous backing tape of a porous acid resistant material, the continuous backing tape has a longitudinal dimension, a width dimension perpendicular to the longitudinal dimension and a flat upper and lower surface, the continuous web backing has a plurality of raised ribs projecting from at least one flat surface thereof, each of the ribs being a corrugated structure comprising of alternate ridges and grooves, each corrugation of the corrugated structure is formed of and is integral with the material of the continuous back-up tape, each corrugation having an inclined front wall, and an inclined rear wall, an edge formed where the front and rear walls meet, side walls at the outer ends of the edge joined to the front and rear walls cited with the space enclosed by the wall d elantera, the rear wall and the side walls being hollow, and the edges and grooves remaining in alignment not parallel with the longitudinal dimension of the continuous backup tape.

2. The battery separator of claim 1, wherein the continuous backing tape material is microporous polyethylene.

3. The battery separator of claim 1, wherein the edges and grooves are essentially perpendicular to the longitudinal dimension of the continuous backing belt.

4. The battery separator of claim 3, wherein the frequency of the edges is between about 5 and about 25 by 2.54 centimeters. The battery separator of claim 1, wherein the ridges and grooves are at an angle with respect to the longitudinal dimension of the continuous backing belt of between about 20 degrees and about 160 degrees. 6. The battery separator of claim 5, wherein the edges and grooves of at least some of the ribs are at a different angle with respect to the longitudinal dimension of the continuous backing tape than that of the edges and grooves of the backing. the ribs immediately adjacent. The battery separator of claim 6, wherein the edges and grooves of a first set of ribs consisting of each other rib is at an angle with respect to the longitudinal dimension of the continuous backup tape between about 20 degrees and less than about 90 degrees, and the angle of the edges and grooves of a second set of ribs consists of ribs immediately adjacent to the first set of ribs that is at an angle with respect to the longitudinal dimension of the backup web between 160 degrees and more than approximately 90 degrees. The battery separator of claim 1, wherein the edges and grooves of at least some of the ribs are a chevron pattern. A battery separator of claim 1, wherein the ridges and grooves of at least one of the ribs are in a tractor tread pattern. 10. The battery separator of claim 1, wherein the edges and grooves of at least some of the ribs are a continuous sinusoidal pattern. The battery separator of claim 1, wherein the ribs extend parallel to the longitudinal dimension of the continuous backing belt. 12. A method for forming ribs in a battery separator comprising unwinding an essentially flat continuous ribbon of an acid-resistant, porous, leak-resistant separator material of a roll, the continuous ribbon having a flat upper surface and a lower flat surface, feeding the tape continues along a path and enhances the tape in a plurality of narrow bands by subjecting at least one flat face of the continuous plastic forming tape material at a plurality of highlighting sites within the bands to form in each of the bands a corrugated structure that extend from the other flat side of the continuous tape, the corrugated structure having alternative edges and grooves that are not parallel to the longitudinal edges of the continuous tape. The method of claim 12, wherein the embossing is effected by passing the continuous ribbon towards the fastening point formed by the pairs of opposing embossing wheels placed at the locations of the narrow bands. The method of claim 12, wherein the spacer material is microporous polyethylene. 1

5. An apparatus for forming ribs in a continuous battery-separating belt comprising a pair of opposing, rotationally mounted relief cylinders having parallel longitudinal axes, at least one of the cylinders having a plurality of highlighting wheels having an axis common with the cylinder positioned in separate embossing locations along the length of the cylinder, the distance between the embossing locations corresponding to the distance between the ribs to be formed and the continuous belt of the battery separator, and a medium impeller to rotate at least one of the cylinders to enhance. 1

6. The apparatus of claim 15, wherein both embossing cylinders have opposing embossing wheels. The apparatus of claim 15, wherein the opposing enhancing wheels comprise gears having a plurality of interengaging gear teeth.