Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/643—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon in the main chain
  • D06M15/647—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon in the main chain containing polyether sequences
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/42—Block-or graft-polymers containing polysiloxane sequences
  • C08G77/46—Block-or graft-polymers containing polysiloxane sequences containing polyether sequences
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/643—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds containing silicon in the main chain
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M7/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made of other substances with subsequent freeing of the treated goods from the treating medium, e.g. swelling, e.g. polyolefins
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M2200/00—Functionality of the treatment composition and/or properties imparted to the textile material
  • D06M2200/40—Reduced friction resistance, lubricant properties; Sizing compositions
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2933—Coated or with bond, impregnation or core
  • Y10T428/2962—Silane, silicone or siloxane in coating

Definitions

• the present invention relates to a process for the treatment of textile materials, particularly fibres and filaments.
• water soluble or water dispersible amphipathic compounds such as are conventionally termed anionic, cationic and non-ionic surface-active agents to assist in the processing of textile fibres and yarns. These agents are valuable in the processing of textile materials because of their ability to lubricate the fibres and to reduce static electrification. It has also been proposed to employ as processing assistant the above mentioned surface active agents in admixture with conventional water-insoluble oily or waxy lubricants such as hydrocarbon oils and waxes, natural and synthetic waxes, glycerides and the like. These mixtures of surface active agents with oily or waxy lubricants have been applied to the textile materials in undiluted form and also as solutions in organic solvents and as aqueous dispersions or emulsions.
• textile materials made from synthetic polymer fibres having marked hydrophobic properties for example textile materials composed of polyolefines, polyamides, polyesters and polyacrylonitrile, diificulties are sometimes experienced because of failure of the above mentioned processing assistants to spread uniformly over the fibres or yarns.
• a siloxane oxyalkylene block or graft copolymer wherein D is the fibre denier and d is the fibre density in grams per cubic centimetre, and optionally a minor proportion of conventional water insoluble oil or waxy lubricant, and if desired, other minor amounts of additives.
• the amounts of siloxane oxyalkylene block copolymers included in the finishing compositions depend on the denier or titre of the fibre, its density, the concentration of dispersion or solution of the finishing composition applied to the fibre and on the amount of finishing composition which, when applied to the fibre gives optimum processing performance and yarn quality during conversion on textile processing equipment.
• this quantity should be such that when the optimum quantity of finish dispersion has been applied to the fibres from a solution or dispersion and the solvent has been removed by drying, the amount of siloxane oxyalkylene block copolymer deposited on the fibre surface should be between 8X10" g. (2111. and 30 l0 g. cm.- of the surface area of the fibre as calculated, for example, from its titre (denier) and density.
• Preferred amphipathic compounds are the nonionic ICC agents, and preferably those which are water soluble or dispersible but not completely water soluble.
• compositions 'in the form of aqueous dispersions, or solutions Concentrations from 0.5% to 10%, preferably not more than 5%, are suitable.
• Suitable proportions of the ingredients of the compositions are from 30% to of the specified amphipathic compound, from 10% to 30% of silicone block copolymer and, if desired, from 30% to 90% of conventional waxy or oil lubricant, included in the specified amphipathic compound, all percentages being calculated on the total weight of composition of non-aqueous components.
• sufiices to apply from 0.05% to 2% of the components calculated on the diluent free composition, by weight of the textile material.
• fibres composed, for example, of polyethylene terephthalate or isotactic polypropylene are effectively lubricated and static elec trification is suppressed.
• amphipathic compounds or surface active agents which contain a hydrocarbon radical having at least eight carbon atoms.
• the hydrocarbon may be an aliphatic, cycloaliphatic or araliphatic radical.
• suitable amphipathic compounds are as follows:
• alkylene oxide condensates which are preferably Water-soluble and stable at temperatures up to at least C., including polyglycols, their esters and ethers; waxes; sulphated oils and waxes; lubricating oil containing a condensation product of 1 molecular proportion of a fatty alcohol with from 1.5 to 5 molecular proportion of ethylene oxide and a condensation product of 1 molecular proportion of a fatty alcohol with from 15 to 30 molecular proportions of ethylene oxide.
• ethylene and/or propylene oxides which may contain either ethylene or propyl- :ene oxide units or both and their esters, and condensation products of ethylene oxide and/or propylene oxide with linear or branched chain saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or araliphatic carboxylic acids, amides, amines or hydroxyl or thiol compounds.
• the aliphatic, cycloaliphatic, aromatic or araliphatic residue contains at least 8 carbon atoms and may contain further substituents such as hydroxyl, thiol, ether, thioether and amino groups.
• the amides or amines may contain aliphatic, cycloaliphatic, aromatic or araliphatic substituents but should contain at least one reactive hydrogen atom.
• Suitable block copolymers are more fully described in copending US. applications Serial No. 144,324 and Serial No. 188,526, relating to copolymers of polyethers and cyclic siloxanes and in UK. patent specification Numbers 802,688, 804,369 and 880,022.
• Other copolymers which have been found to be especially useful include linear and branched block copolymers having the following structures wherein R is a hydrocarbon residue, R, R" and R are polyether residues having functionalities of l, 2 and more than 2 respectively, and (a) is an integer of 3 or more.
• Preferred block or graft copolymers comprise methyl polysiloxane blocks and oxyalkylene blocks containing from 2 to 4 carbon atoms in the oxyalkylene units.
• methyl polysiloxane-polyoxyalkylene block or graft copolymers in which the polyoxyalkylene blocks are composed of oxyethylene units, or of mixtures of oxyethylene with oxypropylene or oxybutylene units and in which the polyether-silicone ratio is such as to give copolymers which are either soluble or self-dispersible in cold water.
• R is an alkyl group with up to 8 carbon atoms
• x is an integer of 2-4 and may be the same or different in different units
• y is an integer to about 20 or 30
• C H O is a
• branched block copolymers which are especially suitable include compositions having the structure X ZX)y( 2)p( n 2n)m ]3 wherein R is a trifunctional organic residue derived from a polyhydric alcohol R (OH) x is as above and y is 1 to about or 20, R is an alkyl radical with up to 8 carbon atoms, p has a value between about 4 and 12, (OC H is a polyether residue composed of oxyethylene and oxypropylene units in a proportion between 1:2 and 2:1, and having a molecular weight between about 250 and 1500, and the ratio of total polyether blocks to total silicone blocks in the copolymer is between about 1 and 4.
• the Si-OC linkage is again preferably via a secondary OH group.
• branched block copolymers having the structure R"Si[ (OSiMe (OC H OR 3 (2B) wherein R and R are alkyl groups with up to 8 carbon atoms, p has a value between about 4 and 9, (OC H is a polyether residue composed of oxyethylene and oxypropylene units in a proportion between 1:2 and 2:1 and having a molecular weight between about 700 and 30 00 and the ratio of the total polyether blocks to the silicone block in the copolymer is in the region of 2 to 4.
• Examples of preferred graft copolymers are compositions having the structure -OSiMe Me Si (OCnHnJmOR (3) wherein the silicone chain is composed of a random as sembly of the units in brackets, (c+d) lies between about 10 and 30, c is at least 2 and no greater than a, R is an alkyl group with up to 8 carbon atoms, (OC H is a polyether residue composed of oxyethylene and oxypropylene units in a proportion between 1:2 and 2:1, and having a molecular weight between about 400 and 3,000, and the weight ratio of total polyether blocks to the silicone block in the copolymer is between about 2 and 5.
• siloxane-oxyalkylene copolymers suitable for use in this invention may be prepared, for example, by the esterification of the siloxane links in polysiloxanes with suitable hydroxy-terminated polyethers, or by reaction of polysiloxanes containing silicon-bonded hydrogen with hydroxy-terminated polyethers with elimination of hydrogen, preferably in presence of known catalysts for this type of reaction, or by ester-interchange between hydroxyterminated polyethers and polysiloxanes containing lower alkoxy groups.
• siloxane-oxyalkylene block copolymers in which the polysiloxane and polyoxyalkylene blocks are united through Si-OC- linkages, other copolymers in which the different blocks are united through SiC linkages may be used.
• Suitable copolymers of this type may be made by reaction of polysiloxanes containing silicon bonded hydrogen with unsaturated polyethers in presence of known catalysts for this type of condensation.
• siloxane polyoxyalkylene copolymers linked by SiC bonds may also be made by the following methods:
• hydrophobic fibres of essentially circular crosssection such as polyethylene terephthalate Terylene (R.T.M.) and isotactic polypropylene fibres, which have a non-polar surface
• the quantity 'y is smaller than that for more polar fibre surfaces, such as wool, cotton and viscose, so that on hydrophobic fibre surfaces it is more diflicult to obtain a film of the textile processing aid.
• Two dilute aqueous solutions containing between 1% and 5% of the compounds are prepared, one serving as a control and the other containing between 1 and 20% of a siloxane oxyalkylene block or graft copolymer, the percentage being based on the weight of the compound in the dispersion.
• a small amount (0.005 cc.) of the liquid and control are measured with a micrometer syringe on a horizontally laid film of fibre forming polymer.
• biaxially oriented polyethylene terephthalate and stereospecific polypropylene films were used. The water is allowed to evaporate at room temperature and the films are then heated in an oven at C. for 10 minutes. The average diameter or areas of the drops are then measured.
• Test liquids which are effective as spreading agents cause the diameter of the wetted surface of the film to be at least two times the diameter, or four times the area, of the wetted surface after heating, compared with the control.
• Another test involving measuring the electrical resistance of a monofilament coated with a solution or dispersion under test is compared with the controls. Because of the non-continuous droplets which are formed by the amphipathic compounds in the absence of an effective siloxane oxyalkylene block copolymer the electrical resistance is higher.
• the third test is described when a suitable dispersion is applied to fibres which are examined for ease of textile processing and regularity as judged by nep content, frictional properties and static charge generation.
• Examples 1, 2, 3 and 4 illustrate the eiiect of a spreading agent on the amphipathic compound when applied to film.
• EXAMPLE 1 A 4% aqueous dispersion of an amphipathic compound consisting of solid polyglycol stearate, containing approximately 6 molecules of ethylene oxide per stearate group, was prepared by stirring 20 g. of the polyglycol stearate in 200 ccs. of water heating at 60 C. for half an hour and diluting the dispersion to 500 ccs. From this dispersion, a 2% dispersion called (a) was prepared by adding to 100 ccs. of the 4% dispersion 100 ccs. of an aqueous solution containing 0.8 g. of a spreading aid consisting of a water-soluble siloxane oxyalkylene block copolymer having the approximate structure:
• dispersions (A) and (B) were measured as droplets suificiently spaced apart, onto a plane surface of a piece of clear polyethylene terephthalate film.
• the water was allowed to evaporate at room temperature and left a thin circular smear of the solutes of 4 mm. diameter on the film.
• the film was then placed in an oven at 100 C. for minutes, causing the solute to melt and flow.
• the smears were examined after cooling; dispersion (B) containing the polyglycol stearate alone was only a 5 mm. diameter circular smear, but that produced from dispersion (A) had spread to an irregular smear of about mm. in diameter, showing that the siloxane-oxyalkylene spreading aid had caused the polyglycol stearate to wet and spread on the polyethylene terephthalate film.
• EXAMPLE 2 A similar experiment was performed with amphipathic compound polyglycol monolaurate, a liquid non-aqueous processing agent containing approximately 9 polyethylene glycol units for each lauric acid radical. This agent was soluble in water and solutions were prepared containing 2% of the monolaurate called solution (D) alone and 2% of the monolaurate with 20% of its weight of the same spreading aid as used in Example 1, called solution (C). Droplets of volume 0.005 cc. were measured onto a clear polyethylene terephthalate film surface, as in Example 1. As the water evaporated, the radius of the drop from solution (D) containing polyethylene glycol monolaurate alone remained constant and left a smear of 4.0 mm.
• EXAMPLE 4 0.005 mol. of the liquids (A), (B), (C) and (D) were applied to the surface in separate experiments of single monofils of polyethylene terephthalate having a titre of .1500 denier.
• Two insulated clips, mounted 7 mm. apart held the fibre, and were connected to a resistance meter capable of measuring up to 10 ohms resistance.
• the electrical resistance of the fibres with applied liquids (B) and (D) remained greater than 10 ohms during evaporation of the droplets and after heating the monofil to C., indicating that neither the aqueous dispersion or solution, nor the neat agent spread as a continuous sheath along the fibres.
• EXAMPLE 6 5 litres of a suspension containing 1.5% polyglycol stearate and 0.30% of the spreading aid used in Example 1, were prepared as described in Example 1 (dispersion A), and a second dispersion (B) was prepared containing only the polyglycol stearate.
• the dispersions were applied to a heat set crimped polyethylene terephthlate tow of overall denier 270,000, and comprising individual fila- "ments of 1.5 denier, by passing the tow continuously between sprays, the rates of spraying and tow speed being controlled in order to give a level of 0.16% of the poly glycol stearate on the tow in each case.
• the tow was then cut into sections of length 1.5 inches and subjected to a heating operation for 12 minutes at a temperature of 110 C., in order, first to expel the water, and secondly to promote speading of the polyglycol stearate in presence of the spreading aid.
• Samples of the cut fibre were then carded on a cotton card, drafted and finally spun to yarn, and careful notes of the processing behaviour were made at all stages. These were substantiated by measurements of such physical properties of the fibre assemblies as appear relevant to the processing behavior of the fibres.
• a 5% aqueous control dispersion (E) of Opal Wax was prepared by emulsifying the wax with the aid of 20% of its weight of a condensation product 17 moles of ethylene oxide in a mixture of cetyl and oleyl alcohols.
• Dispersion (F) contained in addition to the wax and emulsifying agent 20% of the silicone polyethenoxy compound described in Example 1, this percentage being based on the weight of opal wax in the dispersion.
• Example 9 The experiments of Example 1 were repeated with aqueous dispersions containing 2% by Weight of solid polyglycol stearate and 0.02% by weight of the dispersion of one of the siloxane block copolymers tabled below.
• oHmooR 3 OR is a random copolymer of approximately 17 oxyethylene units and 13 oxypropylene units (Le. a copolymer of equal weights of ethylene oxide and propylene oxide), M.W. ca. 1500.
• OR has a slightly shorter polyether chain and an iso-octyl end group giving it approximately the same molecular weight as in (1) and (2).
• the polycther chain consists of oxyethylene and oxypropylcne units in a 1:1 weight ratio.
• OR has molecular weight ea. 1,000
• OR has molecular weight ea. 2,000
• OR is a 1:1 weight mixture of oxyethylated iso-oetanol, molecular weight ea. 1,400 and (figygropylated iso-oetanol, molecular weight ca.
• OR has molecular weight ea. 1,500....
• OR has molecular weight ca. 2,000....
• OR is an oxypropylated butanol
• OR is an oxypropylated butanol
• OR is a 1:1 weight mixture of oxyethylated methanol, molecular Weight ca. 750 and ggrypropylated iso-oetanol, molecular weight ca.
• Example 10 The experiment of Example 2 was repeated with 2% dispersions of polyglycol laurate each with spreading aids, as listed in the table below, to the extent of 1% of the weight of the polyglycol laurate.
• samples 1 and 2 containing the siloxane copolymers cause spreading in the average diameter of the drops by a factor of at least two, compared with the control.
• a process for treating textile materials, particularly filaments and fibers made from synthetic linear polymers which comprises applying thereto (1) 0.1% to 2.0% by weight, of said textile material, of a water soluble lower alkylene oxide condensate, and (2) between yn D.d a D.d
• a process according to claim 1 comprising applying the lower alkylene oxide condensate and the siloxane oxyalkylene polymer to said textile material in the form of an aqueous composition.
• a process according to claim 2 comprising applying from 0.05% to 2% of the components calculated on the water-free composition, based on the weight of the textile material.
• a process according to claim 1 comprising applying the lower alkylene oxide condensate and the siloxane oxyalkylene polymer to said textile material in the form of a 05-10% aqueous composition.
• a process according to claim 1 comprising applying a composition containing 3090% of the lower alkylene oxide condensate, 30% of silicone block copolymer and from 30-90% of a lubricant selected from the group consisting of waxy and oil lubricants, all percentages being calculated on the total weight of composition of nonaqueous components.
• the lower alkylene oxide condensate is a condensation product of (a) an alkylene oxide selected from the group consisting of ethylene oxide and propylene oxide and (b) a compound condensable with said oxide selected from the group 10 consisting of carboxylic acids, amides, amines, hydroxyl compounds and thiol compounds.
• said lower alkylene oxide condensate is a condensation product of ethylene oxide and an amide containing at least one reactive hydrogen atom.
• said lower alkylene oxide condensate is a condensation product of ethylene oxide and an amine containing at least one reactive hydrogen atom.
• siloxane block copolymer has the structural formula:
• R and R are alkyl groups with up to 8 carbon atoms
• p has a value between 4 and 9
• OC H is a polyether residue composed of oxyethylene and oxypropylene units in a proportion between 1:2 and 2:1 and having a molecular weight between about 700 and 3000 and the ratio of the total polyether blocks to the silicone block in the copolymer is in the region of 2 to 4.
• siloxane block copolymer has the structural formula:
• OCnHzQmOR :2 wherein the silicone chain is composed of a random assembly of the units in brackets (c+d) lies between about 10 and 30, C is at least 2 and no greater than d, R is an alkyl group with up to 8 carbon atoms, (OC,,,H is a polyether residue composed of oxyethylene and oxypropylene units in a proportion between 1:2 and 2:1, and having a molecular weight between about 400 and 3,000, and the weight ratio of total polyether blocks to the silicone block in the copolymer is between about 2 and 5.
• the siloxane block copolymer has the structural formula:
• siloxane block copolymer has the structural formula:
• siloxane block copolymer has the structural formula:
• lower alkylene oxide condensate is polyglycol stearate containing approximately 6 molecules of ethylene oxide per stearate group and the material comprises polyethylene terephthalate.
• lower alkylene oxide condensate is polyglycol monolaurate containing approximately 9 polyethylene glycol units for each lauric acid radical and the material comprises polyethylene terephthalate.
• siloxane oxyalkylene copolymer has the structure wherein R and R" are polyether residues having functionalities of 1 and 2.
• siloxane oxyalkylene copolymer has the structure R" (OSiR OR] wherein R is a hydrocarbon residue, R, R" and R are polyether residues having functionalities of 1, 2 and more 11 than 2 respectively, and (2) is an integer of at least 3 and p is 412.
• copolymer comprises methyl polysiloxane blocks and oxyalkylene blocks containing from 2 to 4 carbon atoms in the oxyalkylene units.
• copolymer is one in which the polyether silicone ratio is such as to give copolymers which are at least self-dispersible in cold water.
• a process according to claim 1 wherein the copolymer comprises the structure in which R is an alkyl group with up to 8 carbon atoms, x is an integer of 24, y is an integer to about 30, (c H O) is a polyether residue comprised of oXyethylene and oxypropylene units in a proportion between 1:2 and 2: 1, and with a molecular weight between about 250 and 1000, p has a value from about 4 to 12 and the weight ratio of total polyether blocks to total silicone blocks is between about 0.6 and 2.5.
• siloxane copolymer comprises the structure wherein R is a trifunctional organic residue derived from a polyhydric alcohol R (OH) x is an integer of 24 and y is 1 to about 20, R" is an alkyl radical with up to 8 carbon atoms, p has a value between about 4 and 12.
• Filaments and fibres as claimed in claim 27 made from polyethylene terephthalate.
• Filaments and fibres as claimed in claim 27 made from isotactic polypropylene.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Silicon Polymers (AREA)

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Cited By (21)

Citations (5)

• 0
  • BE BE618428D patent/BE618428A/xx unknown
  • NL NL279187D patent/NL279187A/xx unknown
• 1961
  • 1961-06-01 GB GB19836/61A patent/GB981814A/en not_active Expired
• 1962
  • 1962-05-28 US US197845A patent/US3140198A/en not_active Expired - Lifetime

Patent Citations (5)

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