Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D407/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having oxygen atoms as the only ring hetero atoms, not provided for by group C07D405/00
  • C07D407/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having oxygen atoms as the only ring hetero atoms, not provided for by group C07D405/00 containing two hetero rings
  • C07D407/10—Heterocyclic compounds containing two or more hetero rings, at least one ring having oxygen atoms as the only ring hetero atoms, not provided for by group C07D405/00 containing two hetero rings linked by a carbon chain containing aromatic rings
• • 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
  • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
  • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
  • D06M13/11—Compounds containing epoxy groups or precursors thereof
• • 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
  • D06M15/55—Epoxy resins
• • 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
  • Y10S8/00—Bleaching and dyeing; fluid treatment and chemical modification of textiles and fibers
  • Y10S8/08—Oxirane

Definitions

• This invention relates to an improved process for the treatment of cellulosic textile materials to impart shrink and crease resistant features.
• this invention relates to the treatment of cellulosic and cellulosic-containing textile fabrics with diepoxydioxanes.
• a further disadvantage noted in the use of the polyepoxides to impart wash-and-wear properties is their inability to be sufficiently resistant to acid hydrolysis to tolerate the presence of the strong acid catalysts which are used conventionally for curing formaldehyde on cellulose.
• Previous attempts to employ polyepoxides in combination with formaldehyde have largely been disappointing due to the acid hydrolysis of the polyepoxide.
• Another object is to provide a process for treating textile materials with a polyepoxide which does not require the use of emulsifying agents or non-aqueous solvents.
• a further object of the present invention is to provide textile treating solutions containing a novel polyepoxide which when applied to a textile fabric can be cured quickly and at low temperatures.
• Another object is to provide a process for treating textile materials with a polyepoxide which is re sistant to acid hydrolysis and can be employed in combi- 3,135,579 Patented June 2, 1964 nation with formaldehyde.
• a further object of this invention is to provide a process for treating textile materials with diepoxydioxanes.
• a still further object is to provide a process for treating textile materials with 2,3-bis(2,3- epoxy-propoxy)-1,4-dioxane.
• this invention is directed to a process for treating cellulosic and cellulosic-containing textile materials whereby the material is rendered both shrink and crease resistant while imparting to the material after laundering a soft, smooth finish without ironing which comprises impregnating the textile material with a diepoxydioxane. Thereafter the material is heated to promote the reaction of the polyepoxide with the fabric and thereby impart the shrink and crease resistant features.
• a further unique advantage of the polyepoxides used in the process of this invention is their resistance to acid hydrolysis. This feature renders the polyepoxide especially attractive for use in blends with formaldehyde which is cured conventionally by strong acid catalysts.
• formaldehyde itself is a highly efficient and inexpensive cross-linking agent a more efficient and economical treatment can be employed to impart the desired wash-and-wear properties to textile fabrics.
• fabrics treated with the aforementioned polyepoxides and formaldehyde possess properties superior to those obtained using the same amount of either of the components separately. For instance, a significantly lower loss of fabric strength was found than when formaldehyde was employed as the sole reactant.
• diepoxydioxanes which are suitable for use in the practice of the instant invention are the bis(epoxyalkoxy)- dioxanes represented by the following formula:
• R represents a divalent hydrocarbon radical of from 1 m3 carbon atoms
• R represents a monovalent radical selected from the group consisting of hydrogen and methyl.
• Illustrative compounds which can be employed include, 2,3-bis(2,3-epoxypropoxy)-1,4-dioxane, 2,5-bis(2,3-epoxypropoxy)-l,4-dioxane,
• the diepoxydioxanes are prepared by the reaction of the corresponding diolefinic diether dioxane precursor, i.e. the bis(alkenyloxy)dioxane, with an organic peracid.
• the peracids contemplated include, for example, the aliphatic pcracids, the cycloaliphatic peracids, the aromatic peracids, and the like.
• the organic hydrocarbon peracids are preferred.
• Illustrative peracids include, for instance, peracetic acid, perpropionic acid, perbutyric acid, perhexanoic acid, perdodecanoic acid, perbenzoic acid, monoperphthalic acid, and the like.
• the lower aliphatic hydrocarbon peracids which contain from 2 to 4 carbon atoms are highly suitable. Peracetic acid is most preferred. It is highly desirable to employ the peracid as a solution in an inert normally liquid organic vehicle such as ethyl acetate, butyl acetate, acetone and the like. A solution comprising from about 10 to about 50 weight percent of peracid, based on the total weight of peracid and inert organic vehicle is suitable; from about 20 to 40 weight percent is preferred.
• the epoxidation reaction can be conducted at a temperature in the range of from about C., and lower, to about 100 C., and higher, and preferably from. about 25 to about 75 C.
• the unreacted diolefinic diether precursor, acid' by-product, unspent peracid, inert vehicle, if employed, and the like can be recovered from the reaction product mixture, for example, by distillation under reduced pressure. Further well-known purification techniques can be employed, as desired.
• the diolefinic diether precursor can be prepared by the reaction of 2,3-dichlorodioxane or 2,5-dichlorodioxane with the appropriate monoethylenically unsaturated alcohol or mixtures thereof, preferably in a molar ratio of one mole of dichlorodioxane to at least two mols of monoethylenically unsaturated alcohol.
• This reaction readily proceeds at room temperature, e.g., about 24 C., and the gaseous hydrogen chloride by-product can be continuously removed during the reaction.
• the desired diolefinic diether precursor can be recovered from the resulting reaction product mixture via conventional techniques such as distillation, fractionation, crystallization, and the like.
• the 2,3-dichlorodioxane reagent can be prepared by reaction of dioxane and chlorine gas, at elevated temperatures, e.g., about 70 to 100 C., in the absence or presence of a catalyst, e.g., stannous chloride. Thereafter, nitrogen gas can be bubbled through the resulting reaction product mixture to remove any unreacted chlorine, if desired. Unreacted dioxane can be removed from said reaction product mixture by conventional means, e.g., distillation under reduced pressure, thus giving 2,3-dichlorodioxane.
• a catalyst e.g., stannous chloride
• the 2,5-dichlorodioxane reagent can be prepared by the il reaction of dioxane and chlorine gas, at relatively low temperatures, e.g., about 30 C. to about 0 C., generally in the presence of an inert normally liquid organic vehicle, e.g., carbon tetrachloride.
• the resulting reaction product mixture then can be cooled in a Dry Ice bath which causes 2,5-dichlorodioxane to crystallize from said reaction product mixture.
• the 2,5-dichlorodioxane is readily recovered therefrom via well-known techniques, e.g., crystallization.
• the objectives of the present invention can best be achieved by impregnating the fabric with an aqueous medium containing the bis(epoxyalkoxy)dioxane and a curing catalyst. Impregnation is effected by a conventional padding operation. Thereafter the fabric is dried at a low temperature and then cured at a temperature sufiicient to promote the reaction of the polyepoxide with the cellulose.
• aqueous medium as used throughout the specification and claims is intended to encompass textile treating solutions wherein the solvent medium is solely water, mixtures of water and emulsifying agents, or mixtures of water and organic solvents miscible with water.
• the solvent medium is solely water, mixtures of water and emulsifying agents, or mixtures of water and organic solvents miscible with water.
• the polyepoxide finishes generally in use are not easily dispersed in an aqueous treating bath to give a homogeneous solution because of a low degree of water solubility
• the bis(epoxyalkoxy) dioxanes, particularly 2,3-bis(2,3- epoxypropoxy)1,4-dioxane have a distinct advantage of being miscible in most all proportions with water at 25 C.
• emulsifying agents or organic solvents may be needed, however, in those instances when water insoluble components are added to the textile treating solution.
• emulsifying agents and solvents which can be employed if required are methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium alginate, polyvinyl alcohol, polyethylene oxide, toluene, Xylene, the lower aliphatic alcohols such as ethyl alcohol, butyl alcohol, isopropyl alcohol, acetone, esters, and the like.
• concentration of emulsifying agent is not necessarily critical and can vary in amounts from about 0.1 to 15 percent of the solution.
• the curing step can be accomplished by heating, it can be accelerated by the use of a suitable curing catalyst.
• the catalysts employed are the so-called acidacting curing agents or epoxy curing agents which include not only acids but compounds capable of acting as acids, such as acidic salts, Lewis acids, and the like. Examples of the acid-acting or epoxy curing agents inthe fabric.
• organic and inorganic acids and their anhydrides such as phosphoric acid, hydrochloric acid, boric acid, the alkane sulfonic acids, perchloric acid, persulfuric acid, p-toluenesulfonic acid, citric-acid, acetic acid, acetic acid anhydride, bntyric acid, caproic acid, phthalic acid, phthalic acid anhydride, tartaric acid, oxalic acid, succinic acid, succinic acid anhydride, fumaric acid, glutaconic acid, malonic acid, acetoacetic acid, and naphthalic acid; metal salts such as the fiuo borates of magnesium, tin, cadmium and sodium as well as zinc, boron trifluoride etherate, stannic chloride, aluminurn chloride, magnesium chloride, sodium sulfate, zinc sulfate, and aluminum sulfate,
• the optimum amount of polyepoxide to be applied to the textile material is an amount sufficient to give a desired wash-and-wear rating of 4 or 5 as hereinafter indicated.
• a preferred method is to immerse the fabric in an aqueous medium containing from about .1 to about 30 percent by weight of the polyepoxide, and from 0.01 to 10 percent of the curing catalyst and then pass it through a squeeze roller.
• a second immersion and squeezing can be elfected if necessary, leaving the fabric impregnated with approximately 60 to 100 percent of its own weight of solution.
• the fabric is mounted on a pin frame and dried at relatively low temperatures to remove Water. While drying may be accomplished by allowing the fabric to remain in contact with the air, a temperature range of from about 95 F. to about 175 F. for 5 to 1 minutes is preferred. Since the drying time is not critical, a wider range of drying temperature can be employed equally as well.
• the fabric Upon drying, the fabric is cured at a temperature sufiicient to promote the reaction of the polyepoxide with the fibrous material being treated. Temperatures from about 240 to about 400 F. and more preferably from about 275 F. to about 350 F. can be employed for periods ranging from about secondsto about 5 minutes, with the higher temperatures using the shorter curing period.
• the fabric is scoured to remove unreacted polyepoxide or epoxy curing catalyst. Scouring is effected by washing in hot water (approximately 170 F.) containing a small quantity of detergent. The scouring conditions themselves are not critical as long as unreacted material is removed from After scouring, the fabric is dried and evaluated.
• the textile treating solutions can include mixtures of one or more polyepoxides and one or more knowntextile finishes, including the nitrogen-containing finishes, either alone or in the presence of an epoxy curing catalyst.
• blends of the his (epoxyalkoxy)dioxane and formaldehyde are of particu- Hunter multipurpose reflectometer.
• the bis(epoxyalkoxy)dioxanes are resistant to acid hydrolysis, they are ideally suited for use in conjunction with the less expensive formaldehyde. Moreover, their combined use has a synergistic effect and imparts a higher degree of crease recovery and breaking strength retention than the use of a comparable amount of each finish alone.
• the polyepoxide should comprise at least 15 weight percent, and more preferably from about 15 to about 90 weight percent based on the weight of the mixture.
• the textile treating solution employed for imparting the wash-and-Wear characteristics to the .cellulosic or cellulosic-containing materials can also contain, in addition to the aforementioned polyepoxides, plasticizers, natural resins, textile softening agents and the like.
• the cellulosic textile fabrics used to illustrate the process of this invention were 80 x 80 cotton print cloth and 80 x 80 staple rayon fabric.
• the fabric was white, had been scoured and bleached, and was in suitable condition for application of resin treatment.
• (e) Color the yellowness of the treated fabric was determined by comparison with the original bleached fabric.
• the yellowness index was determined using a This abridged spectrophotometer employs three filters in measuring the 45, 0 reflectance of a fabric with respect to amber, green and blue light.
• a simple yellowness index is provided by where A, B and G represent the reflectances in amber, blue and green light, respectively. The index so obtained correlates closely with subjective evaluations.
• a white fabric has a yellowness which approaches zero, while an index in the range of 0.2 or 0.3 describes a very yellow sample.
• Dry add-on determined by measuring the increase in weight of the fabric after treatment with the polyepoxide, and scouring to remove unreacted material; is a Yellowness A measurement of the total epoxide which had reacted with the fiber.
• 2,3 -B is(2,3 -E poxypropoxy -1 ,4 -D ioxane
• A Preparation of 2,3-diallyl0xy-1,4-di0xane.-A mixture of 872 grams of an aqueous glyoxal solution (containing 26.6 weight percent glyoxal and 8.8 weight percent ethylene glycol), 170 grams of ethylene glycol, 696 grams of allyl alcohol, and 3 grams of sulfuric acid was charged to the kettle of a still which was fitted with a decanting head. The mixture was boiled under reflux until the theoretical amount of water was removed overhead using 600 milliliters of benzene as the azeotroping agent.
• the catalyst wasthen neutralized with sodium acetate and the mixture rapidly distilled to give, after removal of the low-boiling materials, 400 grams of product having a boiling point of 8392 C. at a pressure of 3 millimeters of mercury. Redistillation of the product gave 310 grams of 2,3-diallyloxy-1,4-dioxane having a boiling point of 75 -77 C. at a pressure of 0.6 millimeters of mercury, and a refractive index, N of 1.4549.
• EXAMPLE 2 A treating solution was prepared containing 12.5 weight percent of bis-2,3-(2,3-epoxypropoxy)-1,4-dioxane, 1.25 percent zinc fluoborate and the remainder water. A sample of 80 x 80 cotton print cloth was immersed in this solution, padded to a wet pick-up of approximately 85 percent of the fabric weight, air dried for three minutes at 167 F. and then cured for three minutes at 248 F. The treated fabric was then laundered with a 0.1 percent solution of a built detergent to remove residual reagents, tumble dried, and evaluated according to the methods described above. The dry add-on after laundering was found to be 9.2 percent. The fabric had a wash-and-wear index of a dry and wet crease recovery of 76 and 73 percent respectively, a yellow index of 0.04 and a breaking strength retention of 54 percent.
• the original untreated fabric was immersed in water, dried and found to have a wash-and-wear index of 1, dry and wet crease recoveries of 43 and 41 percent respectively and yellowness index of 0.03.
• EXAMPLE 4 A treating solution was prepared containing 17.5 weight percent of bis-2,3-(2,3-epoxypropoxy)-1,4-dioxane, 1.9 percent zinc fluoborate, and the remainder Water.
• a sample of 80 x 80 cotton print cloth was immersed in this solution, padded to a wet pick-up of approximately 78 percent of the fabric Weight, air dried for three minutes at 167 F. and then cured for three minutes at 248 F.
• the treated fabric was then laundered with a 0.1 percent solution of a built detergent to remove residual reagents, tumble dried, and evaluated according to the methods described above. The dry add-on after laundering was found to be 11.5 percent.
• the fabric had a wash-andwear index of 5-, a dry and wet crease recovery of 80 and 76 percent respectively, a yellowness index of 0.04, and a breaking strength retention of 54 percent.
• EXAMPLE 5 A treating solution was prepared containing 6.0 weight percent of bis-2,3-(2,3-epoxypropoxy)-1,4-dioxane, 1.0 percent zinc fluoborate, and the remainder Water.
• a sample of 80 x 80 cotton print cloth was immersed in this solution, padded to a wet pick-up of approximately 94 percent of the fabric weight, air dried for three minutes at 167 F. and then cured for three minutes at 248 F.
• the treated fabric was then laundered with a 0.1 percent solution of a built detergent to remove residual reagents, tumble dried, and evaluated according to the methods described above. The dry add-on after laundering was found to be 4.4 percent.
• the fabric had a wash-and-wear index of 3, dry crease recovery of 64 percent, a yellowness index of 0.02, and a breaking strength retention of 58 percent.
• a treating solution was prepared containing 6.0 weight percent of bis-2,3-(2,3-epoxypropoxy)-1,4-dioxane, 0.5 percent zinc fluoborate, and the remainder water.
• a sample of 80 x 80 cotton print cloth was immersed in this solution, padded to a wet pick-up of approximately 98 percent of the fabric weight, air dried for three minutes at 167 F. and then cured for three minutes at 248 F.
• the treated fabric was then laundered with a 0.1 percent solution of a built detergent to remove residual reagents, tumble dried, and evaluated according to the methods described above. The dry add-on after laundering was found to be 3.5 percent.
• the fabric had a wash-and-wear index of 3, a dry crease recovery of 62 percent, a yellowness index of 0.02, and a breaking strength retention of 66 percent.
• EXAMPLE 7 A treating solution was prepared which contained 1.5 weight percent formaldehyde, 0.5 percent zinc fluoborate and the remainder water. A sample of 80 x 80 cotton print cloth was immersed in this solution, padded to a wet pick-up of approximately percent of the fabric weight, dried for three minutes at 167 F. and cured for three minutes at 248 F. The treated fabric was then laundered with a 0.1 percent solution of a built detergent to remove residual reagents and evaluated as in the preceding examples. The dry add-on after laundering was found to be -0.1 percent. The fabric had a wash-andwear index of 3, a crease recovery of 56 percent, a yellowness index of 0.04 and a breaking strength retention of 61 percent.
• EXAMPLE 8 A treating solution was prepared which contained 6.0 weight percent of bis-2,3-(2,3-epoxyprpoxy)-1,4-dioxane, 0.5 percent zinc fluoborate, 1.5 percent formaldehyde and the remainder Water. A sample of 80 x 80 cotton print cloth was immersed in this solution, padded to a wet pick-up of approximately 97 percent of the fabric weight, air dried for three minutes at 167 F. and cured for three minutes at 248? F. The treated fabric was then laundered with a 0.1 percent solution of a built detergent to remove residual reagents and evaluated according to the methods used in the preceding examples. The dry add-on after laundering was found to be 3.6 percent. The fabric had a wash-and-wear index of '4, a crease recovery of 71 percent, a yellowness index of 0.03 and a breaking strength retention of 71 percent.
• EXAMPLE 9 A sample 80 x 80 cotton print cloth was treated as described in Example 8. The treated fabric was then subjected to an acid stripping procedure involving immersion in a solution containing 1.5 weight percent of phosphoric acid and percent of urea for five minutes at 170 F. This acid solution which had a pH of 1.9 is capable of stripping most nitrogenous resin treatments from cotton. This treatment also simulates the hydrolytic effects of the acid sour in approximately ten commercial launderings. Prior to the acid stripping procedure the treated cotton had a wash-and-wear index of 4, and a dry crease recovery of 68 percent. After acid stripping the Washand-Wear index was unchanged and the crease recovery was 67 percent. It is therefore evident that the treatment set forth in Example 8 is resistant to acid hydrolysis more severe than that encountered in commercial laundering operations.
• EXAMPLE 10 A solution containing weight percent bis-2,3-(2,3- epoxypropoxy)-1,4-dioxane, 1 percent Zinc fluoborate and the remainder water was allowed to stand at C. and analyzed periodically for epoxide groups. The initial pH of this solution was approximately 3.5. At the end of one hour, more than 99 percent of the original epoxide groups remained, and at the end of four hours 97 percent of the epoxide remained. Thus, under the acidic conditions used in the blend of bis-2,3-(2,3-epoxypropoxy)-1,4-dioxane with formaldehyde hydrolysis of the epoxide in the treating bath does not present any problem.
• a process for treating cellulosic and cellulosic-com taining textile materials whereby said material is rendered both shrink and crease resistant while imparting to said material after laundering a soft smooth finish without ironing which comprises impregnating said textile material with an aqueous medium containing (1) a compound selected from the group consisting of 2,3-bis(vicinal-epoxyalkoxy)-1,4-dioxane and 2,5 -bis(vicinal-epoxyalkoxy) -1,4- dioxane, wherein said vicinal-epoxyalkoxy contains from 3 to 5 carbon atoms and wherein the epoxy group is in a terminal position and separated from etheric oxygen by at least 1 carbon atom; and (2) an epoxy curing catalyst; and thereafter drying and heating said impregnated textile material.
• a process as claimed in claim 1 wherein the textile material is rayon.
• a process for treating cellulosic and cellulosic-containing textile materials whereby said material is rendered both shrink and crease resistant While imparting to said material after laundering a soft smooth finish without ironing which comprises impregnating said textile material with an aqueous medium containing (1) 2,3-bis(vicinalepoxyalkoxy)-1,4-dioxane wherein said vicinal-epoxyalkoxy contains from 3 to 5 carbon atoms and wherein the epoxy group is in a terminal position and separated from etheric oxygen by at least 1 carbon atom; and (2) an epoxy curing catalyst; and thereafter drying and heating said impregnated textile material.
• a process for treating cellulosic and cellulosic-containing material whereby said material is rendered both shrink and crease resistant while imparting to said material after laundering a soft, smooth finish without ironing which comprises impregnating said textile material with an aqueous medium containing from about 1 to about 30 percent by weight, based on said medium, of 2,3-bis(2,3- epoxypropoxy)-l,4-dioxane and from about 0.01 to about 10 percent by weight of an epoxy curing catalyst; and drying and heating said impregnated textile material.
• a process for treating cellulosic and cellulosic-containing textile materials whereby said material is rendered both shrink and crease resistant while imparting to said material after laundering a soft, smooth finish without ironing which comprises impregnating said textile material with an aqueous medium containing from about 1 to about 30 percent by weight, based on said medium, of a mixture of 2,3-bis(2,3-epoxypropoxy)-1,4-dioxane and formaldehyde, and from about 0.1 to about 10 percent by weight of zinc fiuoborate; and drying and heating said impregnated material.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

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  • BE BE632560D patent/BE632560A/xx unknown
  • NL NL293047D patent/NL293047A/xx unknown
• 1962
  • 1962-05-21 US US196476A patent/US3135579A/en not_active Expired - Lifetime
• 1963
  • 1963-05-10 GB GB18511/63A patent/GB1040728A/en not_active Expired
  • 1963-05-17 DE DEU9815A patent/DE1219438B/de active Pending
  • 1963-05-20 FR FR935424A patent/FR1357395A/fr not_active Expired
  • 1963-05-21 CH CH633863A patent/CH390208A/fr unknown

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