Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
  • D01F6/92—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyesters
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/14—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyester as constituent

Definitions

• This invention relates to improved filter fibers and filters comprising said fibers. More particularly, this invention relates to such filter fibers comprising a polyester and a polyolefin, and filters comprising said fibers.
• Polyesters are well known materials for the manufacture of fibers. Illustrative of such fibers are those described in United States Patent Nos. 4,454,196; 4,410,473; and 4,359,557.
• Polyolefinic materials are well known articles of commerce which have experienced wide acceptance in forming shaped objects and film or sheet material. The use of such materials has extended to the fiber and fabric industries. For example, U. S. Patent Nos. 4,587,154; 4,567,092; 4,562,869; and 4,559,862.
• Fibers containing mixtures of polyolefins and polyesters are known.
• U.S. Patent No. 3,639,505 describes fibers and films composed of a polymer alloy comprising an intimate blend of polyolefin, a minor amount of polyethylene terephthalate and 0.2 to 5 parts per hundred parts of polymer of a toluene sulfonamide compound which are described as having improved receptivity to dispersed dyes.
• Bicomponent fibers are known in the art. For example. Textile World, June 1986 at page 29 describes sheath/core fibers which have an inner core of polyester and have an outer core of polypropylene or polyethylene. Also see Textile World, April 1986, page 31. Bicomponent textile filaments of polyester and nylon are known in the art, and are described in U.S. Pat. No. 3,489,641. According to the aforesaid patent, a yarn that crimps but does not split on heating is obtained by using a particular polyester.
• polyester component of the bicomponent filament a polyester which is free from antimony, it having been determined that antimony in the polyester reacts with nylon to form a deposit in the spinneret which produces a shorter junction line, and thus a weaker junction line.
• antimony in the polyester reacts with nylon to form a deposit in the spinneret which produces a shorter junction line, and thus a weaker junction line.
• bicomponent filaments in which the interfacial junction between the two polymeric components is at least in part jagged.
• U.S. Patent No. 3,781,399 teaches such a bicomponent filament.
• Bicomponent filaments having a cross sectional dumbell shape are known in the art.
• U.S. Patent No. 3,092,892 teaches such bicomponent filaments.
• Other nylon/polyester bicomponent fibers having a dumbell cross sectional shape having a jagged interfacial surface, the polyester being an antimonyfree copolyester having 5-(sodium sulfo) isophthalate units are known.
• U.S. Patent No. 4,439,487 teaches such fibers.
• the surface of such bicomponent filament is at least 75% of one of the polymeric components.
• Still other nylon/polyester bicomponent sheath/core fibers are described in Japan Patent Nos. 49020424, 48048721, 70036337 and 68022350; and U.S. Patent Nos. 4,610,925, 4,457,974 and 4,610,928. Fibers have previously been prepared from blends of polyamides with minor amounts of polyesters such as poly (ethylene terephthalate). Intimate mixing before and during the spinning process has been recognized as necessary to achieve good properties in such blended fibers. It is furthermore known that the fine dispersions in fibers of polymer blends are achieved when both phases have common characteristics such as melt viscosity. See D.R. Paul, "Fibers From Polymer Blends" in Polymer Blends, vol. 2, pp. 167-217 at 184 (D.R. Paul & S. Newman, ehs., Academic Press 1978).
• 210-214 (1983) disclose a process for preparing block and/or graft copolymers by forming an intimate mixture of two or more polymers at least one of which includes one or more amino functions, as for example a nylon, and at least one of the remaining polymers includes one or more carboxylic acid functions, as for example a polyester, and a phosphite compound; and thereafter heating the intimate mixture to form the desired block and/or graft copolymers.
• U.S. Patent No. 4,417,031 disclose that such copolymers can be spun into fibers.
• polyester fibers as the filter element for air filters of air breathing engines.
• the use of such fibers is described in Lamb, George, E.R. et al., "Influence of Fiber Properties on the Performance of Nonwoven Air Fillers," Proc. Air Pollut. Control Assoc, vol. 5, pp. 75-57 (June 15-20; 1975) and Lamb, George E.R. et al. "Influence of Fiber Geometry on the Performance of Non Woven Air Filters," Textile Research Journal,” vol. 45 No. 6 pp. 452-463 (1975).
• the present invention is directed to a polyester based fiber useful for the filter element of air filters. More particularly, this invention comprises a polymer fiber comprising predominantly one or more melt spinnable polyesters having non uniformly dispersed therein one or more polyolefins; the concentration of said polyolefin at or near the outer surface of said fiber being greater than the concentration of said polyester at or near the surface of the fiber.
• a "fiber" is an elongated body, the length dimension of which is greater than the transverse dimensions of width and thickness. Accordingly, the term fiber includes single filament, ribbon, strip and the like, having regular or irregular cross-section.
• the fiber of this invention exhibits improved capacity when used as the fibers of the filter element of an air filter.
• Yet another aspect of this invention relates to a process of forming the fiber of this invention which comprises melt spinning a molten mixture comprising as a major component one or more melt spinnable polyesters and as a minor component one or more polyolefins forming a polymer fiber comprising predominantly said one or more polyesters having non uniformly dispersed therein said one or more polyolefins, the concentration of said polyolefins being greater at or near the outer surfaces of said fiber being greater than the concentration of said polyesters at or near the center of said fiber.
• FIGs . 1 to 10 are cross- sec tions of var ious "Mul tilobal" f ibers for use in th is inven tion .
• the fiber of this invention comprises two essential components.
• the fiber is predominantly a melt processible polyester of "fiber forming molecular weight.”
• fiber forming molecular weight is a molecular weight at which the polymer can be melt spun into a fiber.
• Such molecular weights are well known to those of skill in the art and may vary widely depending on a number of known factors, including the specific type of polymer.
• the molecular weight of the polyester is at least about 5,000, and in the particularly preferred embodiments the molecular weight of the polyester is from about 8,000 to about 100,000. Amongst these particularly preferred embodiments, most preferred are those embodiments in which the molecular weight of the polyester is from about 15,000 to about
• Polyester useful in the practice of this invention may vary widely.
• the type of polyester is not critical and the particular polyester chosen for use in any particular situation will depend essentially on the physical properties and features, i.e., desired in the final filter element.
• a multiplicity of linear thermoplastic polyesters having wide variations in physical properties are suitable for use in this invention.
• polyester chosen for use can be a homo-polyester or a co-polyester, or mixtures thereof as desired.
• Polyesters are normally prepared by the condensation of an organic dicarboxylic acid and an organic diol, and, therefore illustrative examples of useful polyesters will be described hereinbelow in terms of these diol and dicarboxylic acid precursors.
• Polyesters which are suitable for use in this invention are those which are derived from the condensation of aromatic, cycloalipha tic, and aliphatic diols with aliphatic, aromatic and cycloalipha tic dicarboxylic acids.
• Illustrative of useful aromatic diols are those having from about 6 to about 12 carbon atoms.
• aromatic diols include bis- (p-hydroxyphenyl) ether; bis-(p-hydroxyphenyl) thioether; (bis-(p-hydroxyphenyl)-sulphone; bis-(p-hydroxyphenyl)-methane; 1,2-(bis-(p-hydroxyphenyl)-ethane; 1-phenyl-(p-hydroxyphenyl)-methane; diphenyl-bis(p-hydroxyphenyl)-methane; 2,2-bis(4'-hydroxy-3'-dimethylphenyl)propane; 1,1- bis(p-hydroxyphenyl)-butane; 2,2-(bis(p-hydroxyphenyl)-butane; 1,1-(bis-(p-hydroxyphenyl)-cyclopentane; 2,2-(bis-(p-hydroxyphenyl)-propane (bisphenol A); 1,1-(bis-(p-hydroxyphenyl)-cyclohexane (bisphenol C); p-xylene glycol;
• Suitable cycloaliphatic diols include those having from about 5 to about 8 carbon atoms. Exemplary of such useful cycloaliphatic diols are 1,4-dihydroxy cyclohexane; 1,4-dihydroxy methylcyclohexane; 1,3-dihydroxycyclopentane; 1,5-dihydroxycycloheptane; 1,5-dihydroxycyclooctane; 1,4-cyclohexane dimethanol; and the like. Polyesters which are derived from aliphatic diols are preferred for use in this invention.
• Useful and preferred aliphatic and cycloalipha tic diols includes those having from about 2 to about 12 carbon atoms, with those having from about 2 to about 6 carbon atoms being particularly preferred.
• Illustrative of such preferred diol precursors are propylene glycols; ethylene glycol, pentane diols, hexane diols, butane diols and geometrical isomers thereof.
• Propylene glycol, ethylene glycol, 1,4-cyclohexane dimethanol, and 1,4-butanediol are particularly preferred as diol precursors of polyesters for use in the conduct of this invention.
• Suitable dicarboxylic acids for use as precursors in the preparation of useful polyesters are linear and branched chain saturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids and cycloaliphatic dicarboxylic acids.
• Illustrative of aliphatic dicarboxylic acids which can be used in this invention are those having from about 2 to about 50 carbon atoms, as for example, oxalic acid, malonic acids, dime thyl-malonic acid, succinic acid, octadecylsuccinic acid, pimelic acid, adipic acid, trimethyladipic acid, sebacic acid, suberic acid, azelaic acid and dimeric acids (dimerisation products of unsaturated aliphatic carboxylic acids such as oleic acid) and alkylated malonic and succinic acids, such as octadecylsuccinic acid, and the like.
• Suitable cycloalipha tic dicarboxylic acids are those having from about 6 to about 15 carbon atoms.
• Such useful cycloalipha tic dicarboxylic acids include 1,3-cyclobutanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and 1,4-dicarboxymethylcyclohexane and 4,4'-dicyclohexydicarboxylic acid, and the like.
• Polyester compounds prepared from the condensation of a diol and an aromatic dicarboxylic acid are preferred for use in this invention.
• aromatic carboxylic acids are terephthalic acid, isophthalic acid and a o-phthalic acid, 1,3-, 1,4-, 2,6 or 2,7-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylsulphone-dicarboxylic acid, 1,1,3-trimethyl-5-carboxy-3-(p-carboxyphenyl)-indane, diphenyl ether 4,4'-dicarboxylic acid bis-p(carboxyphenyl) methane and the like.
• terephthalic acid is particularly preferred.
• poly (ethylene terephthalate), poly(butylene terephthalate), and poly(1,4-cyclohexane dimethylene terephthalate) are the polyesters of choice. Among these polyesters of choice, poly(ethylene terephthalate is most preferred.
• the amount of polyester included in the fiber of this invention may vary widely. In general, the amount of polyester will vary from about 99.5 to about 75 percent by weight based on the total weight of the fiber. In the preferred embodiments of the invention the amount of polyester in the fiber may vary from about 99 to about 85 percent by weight based on the total weight of the fiber, and in the particularly perferred embodiments of the invention the amount of polyester in the fiber may vary from about 90 to about 98 weight percent on the aforementioned basis. Amongst these partcularly preferred embodiments, most preferred are those embodiments in which the amount of polyester in the fiber is from about 92 to about 95 weight percent based on the total weight of the fiber.
• the fiber of this invention includes one or more polyolefins.
• the molecular weight of the polyolefin may vary widely.
• the polyolefin may be a wax having a relatively low molecuar weight i.e., 500 to 1,000 or more.
• the polyolefin may also be melt spinnable and of fiber forming molecular weight.
• Such polyolefins for use in the practice of this invention are well known.
• the polyolefin is of fiber forming molecular weight having a molecular weight of at least about 5,000.
• the molecular weight of the polyolefins is from about 8,000 to about 1,000,000 and in the particularly preferred embodiments is from about 25,000 to about 750,000. Amongst the particularly preferred embodiments most preferred are those in which the molecular weight of the polyolefins is from about 50,000 to about 500,000.
• Illustrative of polyolefins for use in the practice of this invention are those formed by the polymerization of olefins of the formula:
• R 1 and R 2 are the same or different and are hydrogen or substituted or unsubstituted alkylphenyl, phenylalkyl, phenyl, or alkyl.
• Useful polyolefins include polystyrene, polyethylene, polypropylene, polyl(1-octadecene), polyisobutylene, poly(1-pentene), poly(2-methylstyrene), poly(4-methylstyrene), poly(1- hexene), poly(5-methyl-1-hexene), poly(4-methylpentene), poly(1-butene), poly(3-methyl-1-butene), poly(3-phenyl- 1-propene), polybutylene, poly(methyl pentene-1), poly(1-hexene), poly(5-methyl-1-hexene), poly(1-octadecene), poly(vinyl cyclopentane), poly(vinylcyclohe
• polyolefins of the above referenced formula in which R is hydrogen or alkyl having from 1 to about 12 carbon atoms such as polyethylene, polypropylene, polyisobutylene, poly(4-methyl-1-pentene), poly(1-butene), poly(1-pentene), poly(3-methyl-1-butene), poly(1-hexene), poly(5-methyl-1-hexene), poly(1-octene), and the like.
• the polyolefins of choice are those in which R 1 is hydrogen and R 2 is hydrogen or alkyl having from 1 to about 8 carbon atoms such as polyethylene, polypropylene, poly(isobutylene), poly(1-pentene), poly(3-methyl-1-butene), poly(1-hexene), poly(4-methyl-1-pentene), and poly(1-octene).
• R 1 is hydrogen and R 2 is hydrogen or alkyl having from 1 to about 6 carbon atoms such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and polyisobutylene, with polypropylene being the polyolefin of choice.
• the amount of polyolefins included in the fiber of the invention may vary widely and is usually from about 0.5 to about 25 percent by weight based on the total weight of the fiber.
• the amount of melt spinnable polyolefins is from about 1 to about 15 weight percent based on the total weight of the fiber; and in the particularly preferred embodiments of the invention the amount of melt spinnable polyolefins in the fiber is from about 2 to about 10 weight percent based on the total weight of the fiber.
• the amount of melt spinnable polyolefins is from about 3 to about 8.5 percent by weight based on the total weight of the fiber.
• the polyolefins are not uniformly dispersed throughout the polyester continuous phase. Rather, the concentration of the melt spinnable polyolefins at or near the surface of the fiber is higher than the concentration of the melt spinnable polyester at or near the surface of the fiber.
• the result is a fiber which when used in a fiber filter element has a higher capacity and efficiency as compared to polyester fibers which do not contain melt spinnable polyolefins.
• the surface of the fiber is at least about 50 A of the fiber surface.
• the weight percent of the polyolefin component in the portion of the fiber forming a sheath about all or a portion of the longitudinal axis of the fiber said sheath having a thickness of at least about 50 A is at least about 50 weight percent based on the total weight of the sheath.
• the amount of polyolefins contained in said sheath is at least about 80 percent by weight based on the total weight of the sheath, and in the most preferred embodiments the amount of polyolefins contained in the sheath is at least about 85 weight percent to about 98 weight percent being the amount of choice.
• optional ingredients which are normally included in polyester fibers, may be added to the mixture at an appropriate time during the conduct of the process. Normally, these optional ingredients can be added either prior to or after melting of the polyester or polyolefin or a mixture of the polyester and polyolefin
• Such optional components include fillers, plasticizers, colorants, mold release agents, antioxidants, ultra violet light stabilizers, lubricants, anti-static agents, fire retardants, and the like.
• the cross-sectional shape of the fiber is not critical and can vary widely.
• the fiber may have an irregular cross section or a regular cross section.
• the fiber can be flat sheets or ribbons, regular or irregular cylinders, or can have two or more regular or irregular lobes or vanes projecting from the center of axis of the fiber, such fibers are hereinafter referred to as "multilobal" fibers.
• multilobal fibers Illustrative of such multilobal fibers are trilobal, hexalobal, pentalobal, tetralobal, and octalobal filament fibers.
• the fibers are filament fibers having a multilobal cross section such that the surface area of the fiber is maximized, such as fibers having the representative cross-sections depicted in FIGs 1 to
• Such preferred fibers are those fibers which are multilobal and having at least about three projecting lobes, or vanes or projections, and in the particularly preferred embodiments of the invention the fiber is multilobal having at least about five projecting lobes, vanes or projections such as hexalobal or octalobal fibers.
• the "modification ratio" of the fiber can affect the effectiveness of the fiber as the filter element of a filter.
• the "modification ratio" of the fiber can affect the effectiveness of the fiber as the filter element of a filter.
• modification ratio is the ratio of the average distance from the tip of the lobes or vanes of the fiber to the longitudinal center of axis of the fiber to the average distance from the base of the lobes or vanes of the fiber to the longitudinal center of axis of the fiber.
• the modification ratio of the fiber is at least about 18, and in the particularly preferred embodiments of the invention is from about 2 to about 7. Amongst these preferred embodiments, most preferred are those embodiments in which the modification ratio of the fiber is from about 2.2 to about 5.
• foamed fibers are implied in the fabrication of the filter elements.
• foamed fibers can be prepared by using conventional foaming techniques, as for example
• the fiber of this invention is prepared by the process of this invention which comprises:
• molten mixture is an intimate mixture which has been heated to a temperature which is equal to or greater than the melting point of the highest melting polymer component of the mixture or an intimate mixture formed by melting one polymer and dispersing the other polymer in the melted polymer.
• the manner in which the molten mixture is formed is not critical and conventional methods can be employed.
• the molten mixture can be formed through use of conventional polymer and additive blending means, in which the polymeric components are heated to a temperature equal to or greater than the melting point of the highest melting polymer, and below the degradation temperature of each of the polymers.
• the components of the intimate mixture can be granulated, and the granulated components mixed dry in a suitable mixer, as for example a tumbler or a Branbury Mixer, or the like, as uniformly as possible. Thereafter, the composition is heated in an extruder until the polymer components are melted.
• a suitable mixer as for example a tumbler or a Branbury Mixer, or the like
• Fibers can be melt spun from the molten mixture by conventional spinning techniques.
• the compositions can be melt spun in accordance with the procedures of U.S. Patent Nos. 4,454,196 and 4,410,473.
• Foamed fibers can be melt spun using conventional procedures, as for example by the procedures of U.S. Patent Nos. 4,562,022 and 4,164,603.
• the fibers produced from the composition of this invention can be employed in the many applications in which synthetic fibers are used, and are particularly suited for use in the fabrication of filter elements of various types of air and liquid filters, such as air and liquid filters for industrial applications as for example filters for internal combustion engines, clarification filters for water and other liquids, compressed air filters, industrial air filters and the like employing conventional techniques. Fibers of this invention exhibit enhanced capacity and efficiency when are used as filter elements, as compared to polyesters which do not include minor amounts of the polyolefin.
• the fibers of this invention are also useful in the fabrication of coverstock.
• such fibers can be used as coverstock for absorbant materials in the manufacture of diapers, incontinence pads and the like
• PET Polyethylene terephthalate
• the dry PET was sealed in a jar along with a polyolefin and tumbled for fifteen minutes foruniform blending.
• the anhydrous mixture was placed in the hopper of a one inch (2.54 cm) diameter MPM extruder which was preheated to the desired temperature profile along the barrel of the extruder to yield a polymer melt temperature at the exit of the extruder of about 540oF (282° C).
• the screw was 1 inch (2.54 cm) in diameter and 30 inches (76.2 cm) long with a 4:1 compression ratio. It had a standard feed screw configuration with a modified mixing section consisting of a four inch (10.2 cm) long cross hatched zone located seven inches
• the extruder was equipped with a metering pump and a spinning block containing screens (eight layers, 90, 200, 200, 200, 200,
• the spinnerette had twenty (20) symmetrical hexalobal orifices, wherein each lobe has dimension of 4 mils (0.1 mm) (width) ⁇ 25 mils (0.635 mm) (length) ⁇ 20 mils (0.508 mm) (depth).
• the polymer mixture was extruded at a rate of 13 g/rain.
• the filaments exiting from the spinnerette orifices were drawn down while being cooled in air to a temperature at which the filaments did not stick to the surface of a first take-up roll. Just above the first take-up roll, a finish was applied to the yarn to aid further processing and to dissipate any static charge buildup.
• the yarn on the first take-up roll was then drawn in line.
• the yarn on the first take-up roll which turned at 1670 rpm (2800 ft/sec) (853 m/sec) yarn speed was advanced to a second roll which turned at 4482 rpm (6500 ft/sec) (1981 m/sec) and from a second roll onto a third roll which turned also at 4482 rpm (6500 ft/sec) (1981 m/sec).
• the yarn was then advanced from the third roll to a Leesona winder at 6500 ft/sec (1981 m/sec), which wound the yarn upon a sleeve.
• the temperature of the rolls (heated by induction heating) were 120°C, 160°C and 23°C for rolls 1, 2 and 3 respectively. The results are set forth in the following Table I.
• PMP spinning grade polymethylpentene obtained from Mitsui Corporation under the trade name TPX.
• liquid nitrogen was passed through the sample holder to cool the specimen to a temperature of ca. -70°C as measured by a thermocouple.
• the analysis was performed on a PHI Model 560 electron spectrometer using MgK ⁇ radiation as the excitation source.
• Example III the PP concentration within that portion ofthe fiber from 50 to 60 ⁇ of the surface was determined to be 95-100% and the concentration of PET within this region was from 5 to 0%. This indicated that in contrast to the nylon/PP fiber of Comparative Example I, the concentration of PP in that region within 60 ⁇ of the surface of the fiber is greater than the concentration of PET within that region, even though the concentration of PET within the fiber as a whole is very much greater than that of PP. Similarly, for PET/5% PMP fibers of Example IV, the concentration in the region within 60 ⁇ of the surface of the fiber was determined to be 85-90%, while concentration of PET in this region was 15-10%. For the present experiments, it was not possible to determine if the PP or PMP distribution is homogeneous throughout the analysis volume or if a concentration gradient existed.
• the experimental fibers were crimped or texturized and cut into staple length of approximately 11 ⁇ 2 inch
• the fibers were pre-opened on a roller top card and blended with 3DPF 11 ⁇ 4 inch (3.17 cm) staple crimped Vinyon Fibers (a copolymer binding fiber comprising 85% polyvinyl chloride 15% polyvinyl acetate).
• the blend comprising 2/3 by weight of the experimental fiber or control fiber and 1/3 by weight of the binder fiber.
• a 6 ounce/yd 2 (0.02g/cm 2 ) air laid batting was made on a 12 inch wide laboratory air laying machine known as a Rando Webber. The air laid batting was needle locked on a needle punching machine.
• Dacron ® Polyester Fiber (crimped, 11 ⁇ 2 inch (3.81 cm) staple length) and (2) and experimental 3DPF 100% polyester 3 DPF hexalobal cross section fiber crimped or texturized and cut into a 11 ⁇ 2 inch (3.81 cm) staple length.
• Both the unbacked needle locked air laid batting, and the reemay backed batting were heat stabilized for 5 minutes at 275°F (135°C) in a mechanical convection oven prior to flat sheet filtration performance testing.
• test contaminant was a natural siliceous granular powder obtained from the Arizona desert classified to a specific particle size distribution and marketed by the AC Spark Plug Division of General Motors.
• the particle size distributions of the two test dusts are set forth in the following Table II. Table II
• Dust Removal efficiency of fine and coarse particles was determined by obtaining the weight increase of both the test specimen and the absolute filter:
• the Polyester fiber is hexalobal.
• COMPARATIVE EXAMPLE III A series of experiments were carried out to demonstrate that when a polyamide is substituted for a polyester in this invention, the polyolefin is more uniformly dispersed which results in inferior performance when used as a filter medium.
• the fiber of this invention used in the comparison study was the trilobal fiber prepared as described in Example I containing polyethylene terephthalate and 5% by weight PP, and the fiber of Comparative Example 1 containing polypoprolactam and 5% by weight PP.

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• 1988
  • 1988-01-14 AU AU12267/88A patent/AU615176B2/en not_active Expired - Fee Related
  • 1988-01-14 EP EP19880901130 patent/EP0356424A1/en not_active Withdrawn
  • 1988-01-14 JP JP50135388A patent/JPH02500176A/ja active Pending
  • 1988-01-14 WO PCT/US1988/000086 patent/WO1988008463A1/en not_active Application Discontinuation
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