Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
  • D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/22—Polyalkenes, e.g. polystyrene
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
  • D01D10/04—Supporting filaments or the like during their treatment
  • D01D10/0418—Supporting filaments or the like during their treatment as cakes or similar coreless thread packages
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/002—Tissue paper; Absorbent paper
  • D21H27/004—Tissue paper; Absorbent paper characterised by specific parameters
  • D21H27/005—Tissue paper; Absorbent paper characterised by specific parameters relating to physical or mechanical properties, e.g. tensile strength, stretch, softness
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/02—Patterned paper
  • D21H5/025—Webs provided with apertures
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S52/00—Static structures, e.g. buildings
  • Y10S52/07—Synthetic building materials, reinforcements and equivalents

Definitions

• This invention relates to protective wrappers for yarn, thread and like filamentary material of regenerated cellulose wound in the form of an annular package or cake.
• the washed, freshly-spun regenerated cellulose yarn is in the form of a highly swollen gel containing a high proportion of non-regainable moisture, and undergoes strong shrinkage with evaporation of the moisture during the drying step.
• the outer windings of the cake dry more rapidly than the inner windings and because the inner windings are still in the swollen condition, the outer windings cannot shrink as they dry. Stresses and strains are thus set up in the outer windings of the package resulting in what is termed case hardening and the development of non-uniform residual shrinkage capacities and atfinities for dyestuffs along the length of thefilamentary material comprising the cake.
• the rubber sleeve tends to equalize the drying rate at all portions of the cake, it has the disadvantage that it involves the separate operation of placing the sleeve on a stretching device and slipping it over the wrapped package, and of requiring additional handling of the cake while the thread is in the wet condition in which it is most susceptible to damage. Also, the rubber sleeve must be removed after the thread package is dried.
• the object of this invention is to provide a novel
• shrinkable wrapper for annular packages of regenerated cellulose filamentary material which is generally permeable to liquid but which comprises, as an integral part thereof, a portion which is relatively impermeable to moisture and adapted to conform to the outer side wall of the package whereby the evaporation of the moisture from the outer windings of the cake during the drying is retarded, the provision of a separate rubber sleeve being unnecessary.
• a wrapper comprising a shrinkable base sheet of a liquid-permeable paper or paper-like material carrying a firmly adherent coating or film of a moisture-proofing or moisture-repelling elastomer which coating or film occurs only at the outer side wall of the package, shrinks with the base sheet during drying to fit closely against the side wall of the package, and retards the evaporation of moisture from the outer windings during the drying step.
• the shrinkable base sheet is obtained by providing a wrapper for the filamentary package, the portion thereof which is adapted to'conform tothe outer side wall of the package in use is provided with the film or coating of the water-proofing or water-repelling elastomer and dried. This drying is also performed under tension to prevent shrinkage of the sheet.
• the elastomer may be applied after the viscose or an alkaline solution of the cellulose ether has been deposited on the surface of the paper, and prior to regeneration of the cellulose, or neutralization of the alkali if desired.
• the elastomer mechanically bonds with the sheet and with the super imposed regenerated cellulose or cellulose ether deposits, shrinks'with the shrinkable base sheet during drying of the package, and is pulled in close to the outer side wall of the package as the drying proceeds with shrinkage of the package to retard evaporation of the moisture from the outer windings.
• the wrapper is thus provided with a built-in portion which serves the purpose of the separate rubber sleeve heretofore placed on cakes of freshly prepared regenerated cellulose thread prior to initial drying of the thread.
• the elastomer has a vaporimpermeability at least equivalent to the vapor-impermeability of natural rubber, may be initially water-soluble or water-dispersible and applied from aqueous media, organic solvent-soluble and applied from an organic solvent, or it may be applied in molton condition. However, it must be a substance which adheres to the base sheet when it is heated in contact with it and which is non-dispersible in water after heating thereof in situ on the sheet. The film or coating of the elastomer must remain intact during liquidtreatment of the package.
• the elastomer may be thermoplastic or thermosetting and is preferably of the type which does not become sticky during the heating incidental to drying the thread cake.
• the elastomers which may be used are natural rubber latex, Koroseal. (a plasticized polyvinyl chloride), polystyrene, polyethylene, polyvinylidene chloride, polyvinyl chloride, vinyl-chloride-vinyl acetate copolymers, polytetrafluoroethylene, polychlorotrifluoroethylene, polyamides, rubber hydrochlorides, ethylcellulose, polyisobutylene, butadiene polymers and copolymers such as Buna rubber (copolymers of butadiene-1,3 and styrene), isoprene polymers, Thiokol, neoprene, polymerized cashew nut oil, olefine polysulfide plastics, 2,3- dimethyl butadiene polymers, and compositions comprising a mixture
• elastomers are preferably applied in the form of their aqueous emulsions or, where possible, as for example in the case of polyethene, the elastomer may be applied to the base in molten condition.
• the amount of elastomer applied to the shrinkable base sheet is such that the dried film or coating thereof on the wrapper accounts for at least 10% preferably 30-60%, of the total weight of the wrapper.
• the shrinkable wrapper is placed on the annular filamentary package with the coating or film of the elastomer co-extensive with the outer side wall of the package.
• wrapped package is then placed on a perforated arm or rod and processed with liquids from the inside out.
• a perforated arm or rod There is a certain amount of ballooning of the elastomer film or coating during liquid treatment of the wrapped cake, but since the dried elastomer is not dispersible in aqueous media and is resistant to the acids and alkalis to which it is subjected during the liquid-treating, it is not removed or otherwise affected by the treating liquids which penetrate the cake and then run down through the package into the collecting vessel associated with the processing machines without disturbing the film or coating of the clastomer.
• the package is removed from the perforated rod or arm, centrifuged, and taken to the drying room. At this point, the cake is in swollen, distended condition and the wrapper conforms to its contours.
• the regenerated cellulose or cellulose ether deposits on the surface of the wrapper shrink strongly, causing the wrapper to shrink with the thread package and draw the coating or film of the elastomer close to the package wall. Since the elastomer has the same or about the same impermeability to moisture as the rubber sleeve which was placed on the cake in the prior practice, the coating or film of the elastomer on the wrapper retards the evaporation of moisture from the windings of the cake to the same extent as does the rubber sleeve of the prior practice.
• the base sheet to which the coating or film of the elastomer is applied is a shrinkable base sheet, since if the wrapper does not not shrink and fit snugly against the package at the various stages of the drying procedure, and pull the elastomer film or coating bonded to it close to the outer peripheral side wall of the package, the drying rates at the different portions of the package between the outer and inner walls will not be equalized.
• (A) represents annular packages of regenerated cellulose yarn wrapped in the conventional knitted cover and dried in that condition without a protective rubber sleeve
• (B) represents annular regenerated cellulose-yarn packages wrapped in a knitted wrapper and provided with a rubber sleeve during drying
• (C) represents an annular package of regenerated cellulose yarn wrapped in a shrinkable paper wrapper which did not comprise the coating or film of elastomer
• (D) represents annular regenerated cellulose yarn packages wrapped in a shrinkable wrapper comprising a sheet of regenerated cellulose-bonded papermaking fibers having 20% of regenerated cellulose bonded to its surface in the form of continuous parallel stripes and provided with a coating or film of Geon 552 the wrapped package having been dried without the use of a separate rubber sleeve. All of the yarn packages were of the same size and weight, and all were liquid-processed, washed and dried under identical conditions.
• the invention thus accomplishes the same 'results as are achieved when the cake is provided with a knitted fabric wrapper and a rubber sleeve, but has the advantage that the shrinkable paper wrapper is disposable and the use of that wrapper comprising the elastomer coating or film results in a neat final package provided with a closely fitting wrapper which is ready to be shipped and which can be handled without disturbing the windings of the cake.
• the wrapper of the invention it is unnecessary to subject the regenerated cellulose thread" to excessive handling while it is in the gel state, which is distinctly advantageous.
• processing of the thread cake and preparation of the cakes for shipment to the converters are simplified by the elimination of the operation of placing the conventional rubber sleeve on the wrapped cake, and removing it after the drying has been completed.
• the paper having a wet strength of at least 300 gms. on which the viscose or. cellulose ether is deposited to obtain the shrinkable base sheet is a thin paper such as a paper of tissue weight in which the fibers are bonded together by a'bonding material which forms, with the fibers, a coherent seemingly continuous structure.
• it may be'a paper of tissue weight such as 8 to 10 pound paper stock, the fibers of which are bonded together at their points of intersection by regenerated cellulose, a water-insoluble, alkali soluble cellulose ether, a resin, particularly a melamine resin, by a synthetic rubber added to the papermaking stock in the form of a latex, for example a neoprene latex, by autogenous bonding of conventional paper-making fibers and fibers of a potentially adhesive material, or by any other suitable means.
• tissue weight such as 8 to 10 pound paper stock
• the fibers of which are bonded together at their points of intersection by regenerated cellulose, a water-insoluble, alkali soluble cellulose ether, a resin, particularly a melamine resin, by a synthetic rubber added to the papermaking stock in the form of a latex, for example a neoprene latex, by autogenous bonding of conventional paper-making fibers and fibers of a potentially adhesive material
• the paper comprising the paper-making fibers in the bonded condition must have a wet strength such that it will withstand handling and processing in the normal treatment of acid-laden, freshly formed regenerated cellulose yarns.
• the minimum wet strength which the paper may have is 300 gms. across the grain, as determined by the following test:
• a standard Suter Tester having a loading rate of 4 gms./denier per second is equipped with gripping jaws. Strips of the liquid permeable paper 1" wide and 2 /2" long are immersed in water for at least 30 seconds and placed, while wet, between the jaws of the tester. The loading mechanism is then released so that the jaws move away from each other exerting tension on the strip held between them. The tensile strength is indicated automatically on the gauge attached to the tester and is the weight in grams required to tear the strip.
• the Suter Tester iswell-known in industry and is generally used for measuring the tensile strength of yarns.
• the paper of tissue weight made from conventional papermaking fibers is treated with viscose having a low cellulose content for example a viscose containing from 0.6 to 0.9% of cellulose such as is obtained by diluting a normal viscose containing from, 6 to 9% cellulose with water in the ratio of 9 parts of water to 1 part of viscose, and drying the coated paper to obtain a reinforced high wet strength paper having the minimum wet strength of 300 gms., and the fibers of which are bonded together by the viscose. This drying is preferably effected without any substantial regen eration of the cellulose from the viscose.
• viscose having a low cellulose content for example a viscose containing from 0.6 to 0.9% of cellulose such as is obtained by diluting a normal viscose containing from, 6 to 9% cellulose with water in the ratio of 9 parts of water to 1 part of viscose, and drying the coated paper to obtain a reinforced high wet strength paper having
• a thicker viscose for example one containing from 1.5 to 9% cellulose, and preferably from 6 to 9% cellulose, i. e., a viscose of normal cellulose content or such a vis cose which has been diluted with from l to 3 parts of water per part of viscose isqsuperimposed on a surface of the sheet of viscose-bonded fibers in the form of discrete spaced deposits and in an amount such that the dried shrinkable base sheet has from 2 to 40% of regenerated cellulose deposited on its surfaces in the discrete condition after it is treated with sulfuric acid to regenerate the cellulose and dried under tension.
• the viscose superimposed on the base sheet preferably has a sodium chloride salt test value of 3 to 6, a ball fall viscosity of from 30 to 60 seconds, and a sodium hydroxide content of 3 to 6%.
• the paper When the fibers of the base sheet are to be bonded together by a water-insoluble, alkali-soluble cellulose ether, the paper may be treated with an aqueous alkaline solution of the ether, for example, an aqueous sodium hydroxide solution of from 0.5 to 3.0% of the ether.
• an aqueous alkaline solution of the ether for example, an aqueous sodium hydroxide solution of from 0.5 to 3.0% of the ether.
• more concentrated aqueous alkaline solutions may be used, for example aqueous sodium hydroxide solutions containing from 3.5 to 8.0% of ether.
• water-insoluble, alkali-soluble cellulose ether is intended to include simple alkyl ethers, carboxylalkyl ethers, mixed alkyl hydroxyalkyl ethers, mixed alkyl carboxyalkyl ethers and the alkali metal salts of the carboxyalkyl ethers, which are insoluble in water but soluble in aqueous alkaline solutions 'of from 2 to 8% concentration at room temperature or at reduced temperature. These ethers are not dissolved under the conditions to which the thread is subjected during its aftertreatment.
• the base sheet carrying the superimposed viscose or cellulose ether deposits is passed through aqueous sulfuric acid, which may also contain sodium sulfate and zinc sulfate, to regenerate the cellulose, in the case of viscose, or neutralize the alkali, in the case of the cellulose ethers. It is then washed free of acid and dried at fixed dimensions, under tension, to inhibit shrinkage.
• aqueous sulfuric acid which may also contain sodium sulfate and zinc sulfate
• the superimposed discrete spaced deposits which occupy at least and up to 40% of the area of the base sheet, may take any form, such as dots or blobs of any cross section, for example, circular, rectangular, diamond, etc., or they may take the form of streaks, lines, or daubs of any width and length which may be separate or intersect.
• the deposits may take the form of spaced stripes running in any direction relative to the length ofthe paper, and which are either continuous or discontinuous.
• the viscose is superimposed on the sheet of viscose-bonded fibers in the form of parallel stripes from one-sixteenth to two inches wide, spaced apart a distance of one to three inches from edge to edge and which extend circumferentially of the cake when the wrapper is in place thereon.
• These stripes occupy at least 5% of the area of the sheet, and are perferably unbroken, but they may be interrupted at spaced points around the periphery of the thread cake.
• the discrete deposits of viscose or alkali-soluble, water insoluble cellulose ethers are superimposed on the surface of the base sheet as a step in the manufacture of the paper.
• paper sheeted from a pulp or stock comprising conventional paper-making fibers, of tissue weight, and having a wet strength less than 300 gms. may
• This base sheet which has a minimum wet strength of 300 gms., is then passed over one or more drying cans or drums arranged in series as is common in the paper industry, and as it advances over the drying rolls the thicker viscose or a more con centrated solution of the ether is deposited on a surface thereof, most desirably in the form of the continuous parallel stripes referred to above.
• This may be accomplished by supporting a trough above one of the drying rolls and associating with the bottom wall of the trough or on one of the drying rolls means for depositing the viscose or cellulose ether on the paper, for example, the shect may be contacted by an embossing or printing roll provided with parallel grooves and arranged to dip into the viscose or cellulose ether solution and the transfer it to the sheet.
• the proportion of binder in and on the paper necessary to impart the required wet strength is low, and preferably the weight of the paper-making fibers plus the weight of the binder is from 0.5 to 2% greater than the weight of the paper-making fibers alone.
• the weight of the sheet of bonded fibers plus the superimposed spaced deposits of regenerated cellulose or cellulose ether is preferably from at least 2.5% to not more than about 42% greater than the weight of the paper comprising the paper-making fibers only.
• the amount of viscose or cellulose ether superimposed on the sheet of bonded paper-making fibers is selected in the range previously stated so that the wrapper shrinks at least 1% and preferably 5% or more when it is wet out and dried on the thread cake.
• the sheet comprising the regenerated cellulose or cel- V lulose ether superimposed deposits has a minimum air permeability, of 117 cubic feet per minute per square foot of sheet, as determined by the standard air-permeability test (ASTM-D-737-46).
• the paper may be perforated or non-perforated.
• Example I A sheet of non-perforated/paperof tissue weight (8 lb.
• the film of "Geon 552" on the sheet accounted for 40% of the total weight of the sheet.
• a cake of freshly spun regenerated cellulose yarn was wrapped in the sheet, with the stripes of regenerated cellulose extending circumferentially of the cake, and that portion of the wrapper carrying thefilm of Geon 552 co-extensive with the outer side wall of the cake.
• the wrapped cake was then subjected to the usual after-treating liquids including desnlfiding, bleaching, and washing, and finally dried by exposing it to warm air currents.
• the cake of yarn shrank.
• the wrapper shrank with it was drawn in against the cake and conformed to its contours by shrinkage of the stripes of regenerated cellulose.
• the film f Geon 552 was pulled close to-the outer side wall of the cake with the wrapper to prevent premature drying of the outer windings.
• the rate of drying at all portions of the cake was substantially uniform and this equalization of the drying rate was reflected in substantially uniform residual shrinkage and dyeing capacities for all portions of the yarn comprising the cake.
• the percent shrinkage of the yarn at the different portions of the cake and the average shrinkage are given in Table I above, item D.
• the Geon 552 may be diluted with water, dilutions obtained by adding 3 parts of water to'one part of the aqueous emulsion containing 50% solids being satisfactory.
• Example II I A sheet of perforated paper of tissue weight which had a minimum wet strength of 300 gms. and comprised cellulose fibers bonded together by means of neoprene wh ich had been added to the slush stock in the form of a latex at the fan pump was provided with superimposed continuous parallel stripes of viscose containing 7% cellulose. The stripes were A" wide and 1" apart. The sheet was dried under tension passed through a cellulose regenerating bath containing 10% sulfuric acid and of sodium sulfate, washed free of acid, and dried under tension. The weight of this sheet was 15% greater than the weight of the starting paper.
• the wrapper may take the form of a tube or cylinder formed by overlapping the edges of the sheet in any appropriate manner,'as by means of a thermosensitive strip positioned between the edges and rendered adhesive by heating, or one surface of the sheet adjacent one of the edges may be coated with an adhesive material which binds the overlapped edges together.
• the paper may be wrapped around the cake and held on it by merely allowing sufficient overlap.
• the invention includes wrappers formed from paper, and also those formed from paper-like webs or matts of adequate thinness and flexibility to be conformed generally to the peripheries of the package and having a wet strength of at least 300 gms. beforethe spaced regenerated cellulose or cellulose ether deposits are superimposed on it.
• the starting sheet may be formed of a thin web or felt-like structure obtained by associating at least two types of fibers, at least some of the fibers beingof a type which are rendered adhesive by heat or solvent action and which can be returned to non-adhesive condition by cooling or otherwise, so as to form a structure in which the fibers are bonded together autogenously, or by associating a resin or synthetic rubber latex with paper-making fibers before the fibers are sheeted.
• a dry, shrinkable wrapper for annular packages of filamentary material formed of permeable paper and paper-like material of sufficient thinness and flexibility to be conformed readily to both the inner and outer peripheral surfaces of the filamentary package and substantially all of the fibers of which are bonded together to provide a sheet having aminimum wet strength of 300' gms.
• said paper being rendered shrinkable by having from 2 to 40% of a substance selected from the group consisting of regenerated cellulose and water-insoluble, alkali-soluble cellulose ethers superimposed on a surface thereof in the form of discrete, spaced deposits which occupy at least 5% of the area of the sheet, and that portion of the paper adapted to surround the outer side wall of the filamentary package in use having fixed thereto an elastomer which after heating thereof on the paper, is non-dispersible in aqueous media, and which is resistant to acids and alkalis and has a vapor impermeability at least equivalent to the vapor-impermeability of natural rubber, said wrap
• a wrapper as in claim 1 having from 2 to'40% of regenerated cellulose superimposed on a surface thereof in the form of parallel stripes which extend circumferentially of the filamentary package when the wrapper is in use.
• a wrapper as in claim 1 the portion thereof which is adapted to surround the outer side wall of the lilamentafy package in use having fixed thereto an elastomer comprised of polystyrene.
• a dry, shrinkable paper wrapper for annular filamentary packages comprising a liquid-permeable sheet of regenerated cellulose-bonded paper-making fibers having a minimum wet strength of 300 gms. and of sufficient thinness and flexibility to be conformed readily to both the inner and outer peripheries of the package. said sheet having from 2 to 40% of a substance selected from the.
• An assembly comprising an annular. package of freshly-spun regenerated cellulose filamentary material and a shrinkable protective wrapper conformed to the contours of the package and comprising a sheet of paper and paper-like material having a minimum wet strength of 300 gms. and rendered shrinkable by having from 2 to 40% of a substance selected from the group consisting of regenerated cellulose and alkali-soluble, water-insoluble cellulose ethers superimposed on a surface thereof in the form of spaced deposits which occupy at least 5% of the area of the sheet, that portion of the wrapper which is conformed to the outer side wall of the package carrying a flnuly adherent coating of an acid and alkali-resistant,
• permeability at least equivalent to the vapor-impermeability of natural rubber.
• the elastomer is comprised of a mixture of polyvinyl resin and a synthetic rubber.
• the sheet having the minimum wet strength of 300 gms. comprises paper the fibers of which are bonded together by regenerated cellulose.
• the sheet hav-' ing the minimum wet strength of 300 comprises paper the fibers of which are bonded together by a synthetic rubber.
• the sheet having the minimum wet strength of 300 .gms. comprises paper the fibers of which are bonded together by an alkali-soluble, water-insoluble cellulose ether.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Textile Engineering (AREA)
• Laminated Bodies (AREA)
• Packages (AREA)
• Processing Of Meat And Fish (AREA)

Priority Applications (6)

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Publications (1)

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Citations (6)

• 0
  • NL NLAANVRAGE7714321,A patent/NL171454B/nl unknown
  • NL NL78050D patent/NL78050C/xx active
  • BE BE513826D patent/BE513826A/xx unknown
• 1951
  • 1951-09-06 US US245436A patent/US2738060A/en not_active Expired - Lifetime
• 1952
  • 1952-06-05 GB GB14225/52A patent/GB709605A/en not_active Expired
  • 1952-09-03 FR FR1068808D patent/FR1068808A/fr not_active Expired

Patent Citations (6)

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