CA1179459A - Process for producing porous materials and the use thereof - Google Patents
Process for producing porous materials and the use thereofInfo
- Publication number
- CA1179459A CA1179459A CA000395007A CA395007A CA1179459A CA 1179459 A CA1179459 A CA 1179459A CA 000395007 A CA000395007 A CA 000395007A CA 395007 A CA395007 A CA 395007A CA 1179459 A CA1179459 A CA 1179459A
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- CA
- Canada
- Prior art keywords
- substrate
- filler
- pores
- coarse
- micronized
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/429—Natural polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/44—Fibrous material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/491—Porosity
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0002—Aqueous electrolytes
- H01M2300/0005—Acid electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0002—Aqueous electrolytes
- H01M2300/0014—Alkaline electrolytes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Cell Separators (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
- Materials For Medical Uses (AREA)
- Glass Compositions (AREA)
- Filtering Materials (AREA)
Abstract
Abstract of the Disclosure Process for producing porous materials with air resistance values, which are variable within wide limits, as a measure for the pore size. A
coarse-pored substrate is filled with a dispersion of a micronized, agglomeratable filler and the dispersing agent is removed. The filler may be introduced into the coarse-pored substrate by dipping, applying, sponging on, filtering, washing on or spraying on. The filler agglomerates in the pores on removal of the liquid phase. In addition to other fields of application, sub-strates filled in this way are suitable as battery separators, particarly for lead-acid batteries.
coarse-pored substrate is filled with a dispersion of a micronized, agglomeratable filler and the dispersing agent is removed. The filler may be introduced into the coarse-pored substrate by dipping, applying, sponging on, filtering, washing on or spraying on. The filler agglomerates in the pores on removal of the liquid phase. In addition to other fields of application, sub-strates filled in this way are suitable as battery separators, particarly for lead-acid batteries.
Description
~ 7~9 Background of the Invention The invention relates to a process for producing porous materials with air resistance values which are variable within wide limits and which serve as a measure of the pore size of the porous material. More specifically it relates to porous materials having a reduced air permeability achieved by agglomerating inorganic fillers in a coarse-pored structure of preshaped dimensions. The porous materials produced according to the process of this invention are suitable inter alia particularly as battery separators and filter mats or felts of differsnt types.
It is known in the art to apply fillers or powders having a small particle size to the surface of porous substrates and to fix them to the sub-strate by means of bonding agents, condensible resins or sintering to obtain a layer having a smaller pore size, which is at least partially anchored in the substrate layer. As a result, a material is obtained having a smaller pore size. A disadvantage of such a process is that in the case of high filler loadings, or when using sintering, the adhesion of the filler to itself or to the substrate is incomplete, so that it can only undergo limited mechanical loading. This is particularly apparent as sensitivity to vibration and/or abrasion. When high proportions of bonding agents are used there is a risk of obtaining areas that are completely dense due to the non uniform dispersion oE
the filler and the bonding agent which is prejudicial to the intended use.
It is also known to mix fillers with condensible resins and to fill an existing coarse-pored substrate with the mixture. ~n condensing the resin, the filler is anchored to the substrate due to the cured resin layer connecting them. The disadvantages of this process are (1) the limited capacity of commercial resins for fillers due to the viscosity increases occurring with higher filler concentrations, (2) the partial blocking of the surface of the fillers by the resin films and (3~ the changes undergone by the substrate by introducing a condensible resin. Thus, for example, it is difficult to combine a coarse-pored substrate comprised of a low melting polymer with a resin which can only be condensed at a satisfactory speed at elevated temperature, without the coarse-pored substrate losing its shape.
`Summary of the Invention This invention is directed to a process for producing a porous material with air resistance values, variable within wide limits, and which serve as a measure of the pore size.
By an aspect of the invention a method of changlng pore character-istics in a substrate is provided involving providing a substrate having a plurality of relatively coarse-pores, incorporating a mixture of a dispersing agent and a micronized, agglomeratable filler having a minimum particle size of 10 6 mm, into at least some of said relatively coarse-pores~ and removing the dispersing agent leaving an agglomeration of the microni~ed filler in at least some of the relatively coarse-pores and reducing the relative coarseness of at least some of the relatively coarse-pores.
By another aspect of the invention a filled substrate is provided.
This is a coarse-pored substrate with an agglomerated micronized filler in at least some of the coarse-pores reducing the relative coarseness thereof.
Preferred Embodiment Air resistance value in the sense of this application is the time, determined by means of a suitable measuring instrument, necessary for forcing a given quantity of air under a predetermined pressure through a testpiece of a specified area. The smaller the pores in the testplace~ the longer the time required for passing a given quantity of air. The air resistance values given in the description and claims relate to an air quantity of 300 ml, at a pressure . ` ~
., . ~ ., :. ~ :
`` ~.1~7~
of 124.2 mm of water and employing a surface area of 6.45cm2. A type 4110 ~urley densimeter is used in which the indicated air quantities are forced through the testpiece by means of an inner cylinder weighing 567 grams moved through an outer cylinder.
In the process of this invention a given substrate, whose shape and pore structure are fixed by some other method, is treated with a dispersion of micronized fillers in a liquid phase in such a way that the filler is intro-duced into the coarse-pored structure and during the subsequent removal of the liquid phase is agglomerated in the pores, so that the coarse-pored structure of the substrate holds back the agglomerated filler in a plurality of "cages".
This leads to a substantially mechanical retention of the filler so that there is generally no need for a separate chemical bonding agent.
The substrates to be treated by the process of this invention can be of various types and have very different pore shapes and sizes by virtue of the fact that the filler agglomerate being formed adapts to the substrate pore shape. The Examples of substrates which can be used are, for example, cellulose fiber tangled fleeces, fleeces of synthetic fibers, mineral fibers or mixture of said fibers, sintered shaped articles of metal, plastic, glass or other materials, porous materials obtained by Eleece formation, sintering or extraction processes, etc. Lt is obvious that this list of Examples is only representative and not complete.
The lower pore size limit results from the minimum size of the filler particles present in the dispersion and this is in the range of approximately 10 to 10 5 mm in the case of silica based fillers. However, due to rising costs in the production of the dispersion and reduced efficiency regarding the loading of the substrates (grams of filler/m of substrate) there is a minimum practical limit of approximately 10 3 mm for the pore size of the substrate.
~1'79~L~9 Suitable fillers for the process according to this invention are all substances dispersible in liquid mediums and which agglomerate on removing the liquid medium while being compatible with the intended use of the end product.
It is mainly a question of using inorganic fillers such as calcium carbonate, kaolins, silica, talc, diatomaceous earth, etc. Depending on the type of filler, the secondary particles present in the filler as received are broken up by means of stirrers of different types. In particular, it is possible to use high speed, high efficiency stirrers with very high shear forces, turbine stirrers, turbine homogenisers, etc., with the Ultraturrax apparatus being used in the tests described hereinafter. In this apparatus, the particles are micronized by the shear forces occurring between the fixed stator and a rotor, rotatingat high speed.
Many fillers are supplied in dispersed form and additional mechanical treatment is unnecessary because the particles are already in the micronized form making it possible to directly use the dispersions.
As stated hereinbefore, the minimum siæe for the filler particles present in the dispersion is between approximately 10 to 10 5 mm. In the case of commercial]y obtainable dispersions oE e.g. silica obtained by flame hydrolysis or precipitated silica, the particle size range is 10 5 to 10 4 mm.
Filler dispersions with particle sizes in this range are very well suited to the process of the invention. In general terms, it is pointed out that fillers with a particle size of approximate]y 10 3 mm are suitable, but that the size should not extend much over 5 x 10 3 mm.
The fillers used according to the invention with the indicated small particle size (primary particles) have the capacity to agglomerate to larger aggregates. The agglomerates (secondary particles) can have a size of 5 x 10 to approximately 10 mm. The agglomerate size of the preferred fillers used is in the range of 5 x 10 4 to 10 mm. These agglomerate size 5~
values are those given by the manufacturers and can vary from the agglomerate sizes actually found in the porous materials produced according to the inven-tion, because in practice it is not possible to determine the agglomerate size in the porous materials according to the invention.
The fillers are mixed at preferably 1 to 40% by weight concen-trations, depending on the filler type with the dispersing agent, which for cost reasons is generally water, followed by batchwise or continuous dispersion for a particular time determined by tests. The substrates are then filled by known processes, e.g. filtration processes, sponging rollers, dipping processes, washing on, spraying on, applying to the surface of the dispersion, etc. As a function of the nature of the process used, the filler, its particle size and the pore size and wettability of the substrate, the dispersion penetrates the pores at a higher or lower speed. However, the penetration must ensure that the air in the pores can escape.
The dispersing agent can be removed by various prior art processes.
In particular, it is possible to use e.g. drying processes by supplying heat, by evaporation in moving gas streams, by evaporation in vacuo, etc. The temperatures, vacuums, gas speeds, etc. which are used are dependent on the dispersing agent, the filler, and the coarse-pored substrates.
Substrates filled in this way are suitable as battery separators, particularly battery separators for lead-acid batteries, as well as for other uses. The conventionally used cellulose or sintered PVC separators or more modern separators made from tangled fleeces produced from synthetic fibers constitute the presently acceptable compromise of operating efficiency (cold starting behavior), service life and costs. As a result of the pore sizes of approximately 5 x 10 3 to 5 x 10 ~ mm present in such separators, the life is limited by dendrite growths (short-circuits). To guarantee an acceptable life, 4S~
the separators must have a certain, undeslred thickness, the separators pro-duced according to the present invention lead to an improvement in the life for the same substrate thickness or the same life with reduced substrate thick-ness or a combination of both values. The preferred absolute loading and air resistance values can be gathered from the claims directed at the use of the porous materials produced according to the invention as battery separators.
Example 1 32g of precipitated silica (FK 320 DS,DEGUSSA, primary particle size approx. 18nm) and 368g of water are treated for 60 seconds with an Ultraturrax apparatus and poured into a flat dish. The filler concentration was 32g/368g+32g or 32 or 8% by weight. A previously cut approximately 0.6mm thick substrate of a cellulose fiber fleece impregnated with phenolic resin and cured out is placed on the surface of the dispersion. Thorough wetting takes place within a few s~.conds. The thus prepared sheet is allowed to drip and is then dried for 15 minutes at 100 C. Any silica particles on the surface can be brushed off.
The weight increase obtained was 14g/m2. The air resistance value rose from 15 seconds for the substrate to approximately 170 seconds for the filled sheet (measurement with a type 4110 Gurley apparatus, 300ml air through-put, 567g applied weight, ~124.2mm water column, 6.45cm2 measuring surface).
~y using solutions with a higher or lower concentration, other dispersing processes and/or conditions, etc any desired air permeability values can be obtained, so that the filtering action of the substrate obtained can be adapted to the intended use.
To check the suitability of the thus obtained substrates for use in lead-acid batteries both the untreated substrate and the filled substrate were incorporated into battery cells having lead-calcium elements (four positive and : ~
~t79~SI~
five negative plates, with a l.Omm plate spacing) and subjected to the service life test of DIN 43 539. The elements separated with unfilled substrates did suffer from a definite capacity ].05S after 94 cycles and no longer met standard after 117 cycles~ However, the elements with the filled substrates only failed after 141 cycles. Evaluation of the substrates after the test revealed that the unfilled substrates, despite the smaller number of cycles, had a larger number of and more severe short-circuits through the substrate, whereas the filled substrates prevented short-circuits due to the smaller pore sizes.
Unfilled Filled substrate substrate Cold starting values after 94 cycles 1.33V/72 sec. 1.48V/106 sec.
Cold starting values after 117 cycles failed 1.40V/74 sec.
Cold starting values after 141 cycles failed failed Example 2 45g of precipitated silica (FK 320 DS) and 255g of water were treated as in Example 1 and used for filling an identical substrate to that of Example 1. The weight increase here was 35 g/m . The air resistance values of the substrate rose from 11 seconds to approximately 150 seconds.
The thus obtained separators were incorporated into lead-acid battery element groups in order to determine their service life.
Unlike in ~xample 1, a grid alloy containing 3.5% antimony was used in order to determine the varying nature of the material adhesion and the structure of the deposited material. The elements were comprised of four positive plates and five negative plates, welded with a l.Omm plate spacing and subjected to a cycle test according to DIN 43 539. The results again show a clear performance advantage in the case of elements with a filled substrate.
:
9'~59 Unfilled Filled substrate substrate Cold starting values after 94 cycles 1.43 V/131 sec. 1.23V/128 sec.
Cold starting values after 141 cycles 1.29V/69 sec. 1.39V/101 sec.
Cold starting values after 153 cycles failed test broken off Assessment of the separators after the test revealed moderate to serious short-circuits with the unfilled substrates and no short-circuits with the filled substrates.
Example 3 A 15% by weight suspension of precipitated silica (FK 320 DS) in water was treated for 30 seconds with an Ultraturrax apparatus and then further used as given in Exarnple 1.
The weight increase was 65g/m , the air resistance value rising from 4 seconds on the untreated substrate to 220 seconds for the filled substrate.
Example 4 A 5% by weight suspension of precipitated silica (~K 320 DS) was prepared in the manner described in Example 1. A sheet of an a~proximately 0.4mm thick s-intered polyvinylchloride material (a sintered-PVC-battery separator from Jungfer Company, Austria) was filled with it. The weight increase was 7g/m and the air resistance value rose from 20 to 100 seconds.
The thus produced porous material was suitable as a battery separator for acid electrolytes.
Example 5 A 35% by weight dispersion of silica (Aerosil K342, DEGUSSA, primary particle size approx. 30 nm) was used in the form supplied for filling an approximately 0.5mm thick substrate constituted by a mixture of synthetic polymer fibers (45% polyethylene, 10% polyester) and glass fibers (36%). The dispersion was not mechanically prepared and the other conditions were as in Example 1.
The weight increase was 270g/m ~ the air resistance value rising from 5 seconds to approximately 2700 seconds. The porous material produced was suitable as a battery separator for acid electrolytes.
Example 6 A 20% by weight dispersion of precipitated silica (VN-2, DEGUSSA, primary particle size approximately 28nm) was treated for 10 minutes with an Ultraturrax apparatus. A substrate of the type indicated in Example 5 was filled with this dispersion. The weight increase was 130g/m and the air resistance va:Lue rose from 5 to 410 seconds. The porous material produced was suitable as a battery separator for acid electrolytes.
_9_
It is known in the art to apply fillers or powders having a small particle size to the surface of porous substrates and to fix them to the sub-strate by means of bonding agents, condensible resins or sintering to obtain a layer having a smaller pore size, which is at least partially anchored in the substrate layer. As a result, a material is obtained having a smaller pore size. A disadvantage of such a process is that in the case of high filler loadings, or when using sintering, the adhesion of the filler to itself or to the substrate is incomplete, so that it can only undergo limited mechanical loading. This is particularly apparent as sensitivity to vibration and/or abrasion. When high proportions of bonding agents are used there is a risk of obtaining areas that are completely dense due to the non uniform dispersion oE
the filler and the bonding agent which is prejudicial to the intended use.
It is also known to mix fillers with condensible resins and to fill an existing coarse-pored substrate with the mixture. ~n condensing the resin, the filler is anchored to the substrate due to the cured resin layer connecting them. The disadvantages of this process are (1) the limited capacity of commercial resins for fillers due to the viscosity increases occurring with higher filler concentrations, (2) the partial blocking of the surface of the fillers by the resin films and (3~ the changes undergone by the substrate by introducing a condensible resin. Thus, for example, it is difficult to combine a coarse-pored substrate comprised of a low melting polymer with a resin which can only be condensed at a satisfactory speed at elevated temperature, without the coarse-pored substrate losing its shape.
`Summary of the Invention This invention is directed to a process for producing a porous material with air resistance values, variable within wide limits, and which serve as a measure of the pore size.
By an aspect of the invention a method of changlng pore character-istics in a substrate is provided involving providing a substrate having a plurality of relatively coarse-pores, incorporating a mixture of a dispersing agent and a micronized, agglomeratable filler having a minimum particle size of 10 6 mm, into at least some of said relatively coarse-pores~ and removing the dispersing agent leaving an agglomeration of the microni~ed filler in at least some of the relatively coarse-pores and reducing the relative coarseness of at least some of the relatively coarse-pores.
By another aspect of the invention a filled substrate is provided.
This is a coarse-pored substrate with an agglomerated micronized filler in at least some of the coarse-pores reducing the relative coarseness thereof.
Preferred Embodiment Air resistance value in the sense of this application is the time, determined by means of a suitable measuring instrument, necessary for forcing a given quantity of air under a predetermined pressure through a testpiece of a specified area. The smaller the pores in the testplace~ the longer the time required for passing a given quantity of air. The air resistance values given in the description and claims relate to an air quantity of 300 ml, at a pressure . ` ~
., . ~ ., :. ~ :
`` ~.1~7~
of 124.2 mm of water and employing a surface area of 6.45cm2. A type 4110 ~urley densimeter is used in which the indicated air quantities are forced through the testpiece by means of an inner cylinder weighing 567 grams moved through an outer cylinder.
In the process of this invention a given substrate, whose shape and pore structure are fixed by some other method, is treated with a dispersion of micronized fillers in a liquid phase in such a way that the filler is intro-duced into the coarse-pored structure and during the subsequent removal of the liquid phase is agglomerated in the pores, so that the coarse-pored structure of the substrate holds back the agglomerated filler in a plurality of "cages".
This leads to a substantially mechanical retention of the filler so that there is generally no need for a separate chemical bonding agent.
The substrates to be treated by the process of this invention can be of various types and have very different pore shapes and sizes by virtue of the fact that the filler agglomerate being formed adapts to the substrate pore shape. The Examples of substrates which can be used are, for example, cellulose fiber tangled fleeces, fleeces of synthetic fibers, mineral fibers or mixture of said fibers, sintered shaped articles of metal, plastic, glass or other materials, porous materials obtained by Eleece formation, sintering or extraction processes, etc. Lt is obvious that this list of Examples is only representative and not complete.
The lower pore size limit results from the minimum size of the filler particles present in the dispersion and this is in the range of approximately 10 to 10 5 mm in the case of silica based fillers. However, due to rising costs in the production of the dispersion and reduced efficiency regarding the loading of the substrates (grams of filler/m of substrate) there is a minimum practical limit of approximately 10 3 mm for the pore size of the substrate.
~1'79~L~9 Suitable fillers for the process according to this invention are all substances dispersible in liquid mediums and which agglomerate on removing the liquid medium while being compatible with the intended use of the end product.
It is mainly a question of using inorganic fillers such as calcium carbonate, kaolins, silica, talc, diatomaceous earth, etc. Depending on the type of filler, the secondary particles present in the filler as received are broken up by means of stirrers of different types. In particular, it is possible to use high speed, high efficiency stirrers with very high shear forces, turbine stirrers, turbine homogenisers, etc., with the Ultraturrax apparatus being used in the tests described hereinafter. In this apparatus, the particles are micronized by the shear forces occurring between the fixed stator and a rotor, rotatingat high speed.
Many fillers are supplied in dispersed form and additional mechanical treatment is unnecessary because the particles are already in the micronized form making it possible to directly use the dispersions.
As stated hereinbefore, the minimum siæe for the filler particles present in the dispersion is between approximately 10 to 10 5 mm. In the case of commercial]y obtainable dispersions oE e.g. silica obtained by flame hydrolysis or precipitated silica, the particle size range is 10 5 to 10 4 mm.
Filler dispersions with particle sizes in this range are very well suited to the process of the invention. In general terms, it is pointed out that fillers with a particle size of approximate]y 10 3 mm are suitable, but that the size should not extend much over 5 x 10 3 mm.
The fillers used according to the invention with the indicated small particle size (primary particles) have the capacity to agglomerate to larger aggregates. The agglomerates (secondary particles) can have a size of 5 x 10 to approximately 10 mm. The agglomerate size of the preferred fillers used is in the range of 5 x 10 4 to 10 mm. These agglomerate size 5~
values are those given by the manufacturers and can vary from the agglomerate sizes actually found in the porous materials produced according to the inven-tion, because in practice it is not possible to determine the agglomerate size in the porous materials according to the invention.
The fillers are mixed at preferably 1 to 40% by weight concen-trations, depending on the filler type with the dispersing agent, which for cost reasons is generally water, followed by batchwise or continuous dispersion for a particular time determined by tests. The substrates are then filled by known processes, e.g. filtration processes, sponging rollers, dipping processes, washing on, spraying on, applying to the surface of the dispersion, etc. As a function of the nature of the process used, the filler, its particle size and the pore size and wettability of the substrate, the dispersion penetrates the pores at a higher or lower speed. However, the penetration must ensure that the air in the pores can escape.
The dispersing agent can be removed by various prior art processes.
In particular, it is possible to use e.g. drying processes by supplying heat, by evaporation in moving gas streams, by evaporation in vacuo, etc. The temperatures, vacuums, gas speeds, etc. which are used are dependent on the dispersing agent, the filler, and the coarse-pored substrates.
Substrates filled in this way are suitable as battery separators, particularly battery separators for lead-acid batteries, as well as for other uses. The conventionally used cellulose or sintered PVC separators or more modern separators made from tangled fleeces produced from synthetic fibers constitute the presently acceptable compromise of operating efficiency (cold starting behavior), service life and costs. As a result of the pore sizes of approximately 5 x 10 3 to 5 x 10 ~ mm present in such separators, the life is limited by dendrite growths (short-circuits). To guarantee an acceptable life, 4S~
the separators must have a certain, undeslred thickness, the separators pro-duced according to the present invention lead to an improvement in the life for the same substrate thickness or the same life with reduced substrate thick-ness or a combination of both values. The preferred absolute loading and air resistance values can be gathered from the claims directed at the use of the porous materials produced according to the invention as battery separators.
Example 1 32g of precipitated silica (FK 320 DS,DEGUSSA, primary particle size approx. 18nm) and 368g of water are treated for 60 seconds with an Ultraturrax apparatus and poured into a flat dish. The filler concentration was 32g/368g+32g or 32 or 8% by weight. A previously cut approximately 0.6mm thick substrate of a cellulose fiber fleece impregnated with phenolic resin and cured out is placed on the surface of the dispersion. Thorough wetting takes place within a few s~.conds. The thus prepared sheet is allowed to drip and is then dried for 15 minutes at 100 C. Any silica particles on the surface can be brushed off.
The weight increase obtained was 14g/m2. The air resistance value rose from 15 seconds for the substrate to approximately 170 seconds for the filled sheet (measurement with a type 4110 Gurley apparatus, 300ml air through-put, 567g applied weight, ~124.2mm water column, 6.45cm2 measuring surface).
~y using solutions with a higher or lower concentration, other dispersing processes and/or conditions, etc any desired air permeability values can be obtained, so that the filtering action of the substrate obtained can be adapted to the intended use.
To check the suitability of the thus obtained substrates for use in lead-acid batteries both the untreated substrate and the filled substrate were incorporated into battery cells having lead-calcium elements (four positive and : ~
~t79~SI~
five negative plates, with a l.Omm plate spacing) and subjected to the service life test of DIN 43 539. The elements separated with unfilled substrates did suffer from a definite capacity ].05S after 94 cycles and no longer met standard after 117 cycles~ However, the elements with the filled substrates only failed after 141 cycles. Evaluation of the substrates after the test revealed that the unfilled substrates, despite the smaller number of cycles, had a larger number of and more severe short-circuits through the substrate, whereas the filled substrates prevented short-circuits due to the smaller pore sizes.
Unfilled Filled substrate substrate Cold starting values after 94 cycles 1.33V/72 sec. 1.48V/106 sec.
Cold starting values after 117 cycles failed 1.40V/74 sec.
Cold starting values after 141 cycles failed failed Example 2 45g of precipitated silica (FK 320 DS) and 255g of water were treated as in Example 1 and used for filling an identical substrate to that of Example 1. The weight increase here was 35 g/m . The air resistance values of the substrate rose from 11 seconds to approximately 150 seconds.
The thus obtained separators were incorporated into lead-acid battery element groups in order to determine their service life.
Unlike in ~xample 1, a grid alloy containing 3.5% antimony was used in order to determine the varying nature of the material adhesion and the structure of the deposited material. The elements were comprised of four positive plates and five negative plates, welded with a l.Omm plate spacing and subjected to a cycle test according to DIN 43 539. The results again show a clear performance advantage in the case of elements with a filled substrate.
:
9'~59 Unfilled Filled substrate substrate Cold starting values after 94 cycles 1.43 V/131 sec. 1.23V/128 sec.
Cold starting values after 141 cycles 1.29V/69 sec. 1.39V/101 sec.
Cold starting values after 153 cycles failed test broken off Assessment of the separators after the test revealed moderate to serious short-circuits with the unfilled substrates and no short-circuits with the filled substrates.
Example 3 A 15% by weight suspension of precipitated silica (FK 320 DS) in water was treated for 30 seconds with an Ultraturrax apparatus and then further used as given in Exarnple 1.
The weight increase was 65g/m , the air resistance value rising from 4 seconds on the untreated substrate to 220 seconds for the filled substrate.
Example 4 A 5% by weight suspension of precipitated silica (~K 320 DS) was prepared in the manner described in Example 1. A sheet of an a~proximately 0.4mm thick s-intered polyvinylchloride material (a sintered-PVC-battery separator from Jungfer Company, Austria) was filled with it. The weight increase was 7g/m and the air resistance value rose from 20 to 100 seconds.
The thus produced porous material was suitable as a battery separator for acid electrolytes.
Example 5 A 35% by weight dispersion of silica (Aerosil K342, DEGUSSA, primary particle size approx. 30 nm) was used in the form supplied for filling an approximately 0.5mm thick substrate constituted by a mixture of synthetic polymer fibers (45% polyethylene, 10% polyester) and glass fibers (36%). The dispersion was not mechanically prepared and the other conditions were as in Example 1.
The weight increase was 270g/m ~ the air resistance value rising from 5 seconds to approximately 2700 seconds. The porous material produced was suitable as a battery separator for acid electrolytes.
Example 6 A 20% by weight dispersion of precipitated silica (VN-2, DEGUSSA, primary particle size approximately 28nm) was treated for 10 minutes with an Ultraturrax apparatus. A substrate of the type indicated in Example 5 was filled with this dispersion. The weight increase was 130g/m and the air resistance va:Lue rose from 5 to 410 seconds. The porous material produced was suitable as a battery separator for acid electrolytes.
_9_
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of changing pore characteristics in a substrate comprising providing a substrate having a plurality of relatively coarse-pores, incorpor-ating a mixture of a dispersion agent and a micronized, agglomeratable filler, having a minimum particle size of 10-6 mm, into at least some of said relative-ly coarse-pores, and removing said dispersing agent leaving an agglomeration of said micronized filler in at least some of said relatively coarse-pores and reducing the relative coarseness of at least some of said relatively coarse-pores.
2. A method according to Claim 1, wherein said substrate has substantial-ly all of its pores having a size above about 10-5 mm.
3. A method according to Claim 1, wherein said dispersing agent is water.
4. A method according to Claim 1, wherein said filler is chosen from the group consisting essentially of calcium carbonates, kaolins, silica, talc, diatomaceous earth and mixtures thereof.
5. A method according to Claim 1, wherein said micronized filler has a particle size of about 10-6 to about 10-3 mm.
6. A method according to Claim 1, wherein said mixture of dispersing agent and micronized filler is introduced into said at least some of said relatively coarse-pores by dipping, applying, sponging, filtering, spraying on or washing on.
7. A method according to Claim 1, wherein about 0.1 to about 100g/m2 of filler is incorporated into said substrate per 0.1 mm of substrate thickness.
8. A method according to Claim 1, wherein the substrate air resistance value is increased by a factor of about 1 to about 1000 by the practice of said method.
9. A method according to Claim 1, wherein substantially all of the pores in said substrate have a size above 10-3 mm prior to the incorporation of said mixture; said dispersing agent is water; said filler is predominately siliceous material, has a particle size of about 10-5 mm to about 10-4 mm, and is incorporated into said substrate in an amount of about 1 to about 60g/m2 per 0.1 mm of substrate thickness; and the substrate air resistance value is increased by a factor of about 1 to about 600 by the practice of said method.
10. A filled substrate comprising a coarse-pored substrate and an agglomerated micronized filler in at least some of said coarse-pores reducing the relative coarseness thereof.
11. The filled substrate of Claim 10 wherein said filled substrate is a battery separator.
12. The battery separator of Claim 11 wherein said substantially homogeneous coarse-pored substrate is chosen from the group consisting of phenolic resin-impregnated cellulose fiber tangled fleece, sintered polyvinyl-chloride material and sheets comprising synthetic fibers or mixtures of synthetic and natural fibers.
13. The battery separator of Claim 12 comprising about 1 to about 200 g/m2 of filler and having an air resistance value of about 10 to about 2000 seconds.
14. The battery separator of Claim 13 comprising about 5 to about 50 g/m2 of filler and having an air resistance value of about 20 to about 1000 seconds.
15. The battery separator of Claim 11 being disposed in a battery between a positive and a negative battery plate and separating said positive and said negative battery plates.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3102735A DE3102735C2 (en) | 1981-01-28 | 1981-01-28 | Process for the production of porous bodies and their use |
| DEP3102735.0 | 1981-01-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1179459A true CA1179459A (en) | 1984-12-18 |
Family
ID=6123490
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000395007A Expired CA1179459A (en) | 1981-01-28 | 1982-01-27 | Process for producing porous materials and the use thereof |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0057841B1 (en) |
| JP (1) | JPS57182964A (en) |
| AT (1) | ATE14171T1 (en) |
| AU (1) | AU552123B2 (en) |
| BR (1) | BR8200457A (en) |
| CA (1) | CA1179459A (en) |
| DE (1) | DE3102735C2 (en) |
| NZ (1) | NZ199582A (en) |
| ZA (1) | ZA82379B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3222361C2 (en) * | 1982-06-14 | 1985-03-28 | Grace Gmbh, 2000 Norderstedt | Separators for lead-lead dioxide accumulators and process for their production |
| JP2637389B2 (en) * | 1995-11-10 | 1997-08-06 | 三井東圧化学株式会社 | Porous film or sheet |
| JP4830720B2 (en) * | 2006-08-28 | 2011-12-07 | パナソニック電工株式会社 | Apartment house management call system |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD15371A (en) * | ||||
| AT58848B (en) * | 1911-03-13 | 1913-04-25 | Pascal Marino | Process for the production of diaphragms from substances impregnated with silica. |
| BE493351A (en) * | 1950-01-10 | |||
| BE503863A (en) * | 1950-06-13 | |||
| US3262815A (en) * | 1964-08-11 | 1966-07-26 | Westinghouse Electric Corp | Electrodes for secondary storage batteries |
| DE1771457C3 (en) * | 1968-05-28 | 1974-12-05 | Rheinisch-Westfaelisches Elektrizitaetswerk Ag, 4300 Essen | Process for the production of a zinc dendrite barrier membrane made of metal oxide and plastic |
| US3749604A (en) * | 1970-03-12 | 1973-07-31 | Westinghouse Electric Corp | Heat resistant substrates and battery separators made therefrom |
| DE2134687B2 (en) * | 1971-07-12 | 1973-10-25 | Varta Batterie Ag, 3000 Hannover | Alkaline primary element with a negative electrode in which the zinc powder is suspended in a thickened zinc oxide-containing potassium hydroxide solution |
| JPS5530253B2 (en) * | 1974-03-06 | 1980-08-09 | ||
| JPS50146841A (en) * | 1974-05-15 | 1975-11-25 | ||
| US3985580A (en) * | 1974-11-18 | 1976-10-12 | W. R. Grace & Co. | Wettable polyolefin battery separator |
| GB1553302A (en) * | 1975-06-27 | 1979-09-26 | Amerace Corp | Process for making a flexible plastic battery separator |
| FR2344134A1 (en) * | 1976-03-11 | 1977-10-07 | Chloride Group Ltd | Electrode for lead accumulators, comprises porous polymer substrate - onto which an incomplete grid of lead alloy is cast |
| US4091243A (en) * | 1977-07-26 | 1978-05-23 | Bell Telephone Laboratories, Incorporated | Multifrequency signal receiver |
| JPS5437229A (en) * | 1977-08-29 | 1979-03-19 | Fujikura Ltd | Separator base material for acidic cell and separator using same |
| US4288503A (en) * | 1978-06-16 | 1981-09-08 | Amerace Corporation | Laminated microporous article |
-
1981
- 1981-01-20 ZA ZA82379A patent/ZA82379B/en unknown
- 1981-01-28 DE DE3102735A patent/DE3102735C2/en not_active Expired
-
1982
- 1982-01-22 EP EP82100433A patent/EP0057841B1/en not_active Expired
- 1982-01-22 AT AT82100433T patent/ATE14171T1/en not_active IP Right Cessation
- 1982-01-26 AU AU79849/82A patent/AU552123B2/en not_active Ceased
- 1982-01-27 BR BR8200457A patent/BR8200457A/en unknown
- 1982-01-27 CA CA000395007A patent/CA1179459A/en not_active Expired
- 1982-01-27 JP JP57010252A patent/JPS57182964A/en active Pending
- 1982-01-27 NZ NZ199582A patent/NZ199582A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR8200457A (en) | 1982-11-30 |
| JPS57182964A (en) | 1982-11-11 |
| ATE14171T1 (en) | 1985-07-15 |
| EP0057841B1 (en) | 1985-07-03 |
| EP0057841A2 (en) | 1982-08-18 |
| DE3102735A1 (en) | 1982-08-05 |
| DE3102735C2 (en) | 1988-08-18 |
| EP0057841A3 (en) | 1982-08-25 |
| NZ199582A (en) | 1986-01-24 |
| AU7984982A (en) | 1982-08-05 |
| ZA82379B (en) | 1982-12-29 |
| AU552123B2 (en) | 1986-05-22 |
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