Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/124—Duplicating or marking methods; Sheet materials for use therein using pressure to make a masked colour visible, e.g. to make a coloured support visible, to create an opaque or transparent pattern, or to form colour by uniting colour-forming components
  • B41M5/132—Chemical colour-forming components; Additives or binders therefor
  • B41M5/155—Colour-developing components, e.g. acidic compounds; Additives or binders therefor; Layers containing such colour-developing components, additives or binders
• • 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
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• • 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
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
  • Y10T428/256—Heavy metal or aluminum or compound thereof
• • 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
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
  • Y10T428/258—Alkali metal or alkaline earth metal or compound thereof
• • 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
  • Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
  • Y10T428/273—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.] of coating
• • 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
  • Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
  • Y10T428/273—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.] of coating
  • Y10T428/277—Cellulosic substrate
• • 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
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31942—Of aldehyde or ketone condensation product
  • Y10T428/31949—Next to cellulosic
  • Y10T428/31964—Paper

Definitions

• ABSTRACT A recording sheet comprising a support having coated thereon a layer of a color developer which is capable of forming a distinct color when contacted with a color former.
• the color developer contains a combination of (i) a polymer of an aromatic carboxylic acid having at least one hydroxyl group with an aldehyde or acetylene and (ii) a metallic compound.
• the present invention relates to a recording sheet and a color developer therefor and more particularly to a recording sheet having coated'thereon a novel color developer layer and a novel color developer for the recording sheet.
• Examples of recording sheets using this phenomenon are pressure-sensitive recording sheets suchas in U.S-. Pat. Nos. 2,505,470, 2,505,489, 2,550,471, 2,548,366, 2,712,507, 2,730,456, 2,730,457 and 3,418,250 and well-knownheat-sensitive recording sheets. Further, a printing method. is'k'nown where an ink, containing-the color former, is applied to the color developer sheet through amedium such as a stencil.
• the color former may be dissolved in a solvent such as chlorinated diphenyl, chlorinated paraffin or other organic solvent.
• a solvent such as chlorinated diphenyl, chlorinated paraffin or other organic solvent.
• the solution may be dispersed in a binder and/or may be microencapsulated, and then coated onto a support such as-paper, plastic film, resincoated paper, etc.
• a binder such as a styrene-butadiene rubber latex and then coated'on or impregnated into a base support before or directly before recording.
• a desensitizer is locally coated thereon in order that unnecessary color formation be prevented in certain portions of the surface as shown in US. Pat. No. 2,777,780.
• Another embodiment for the prevention of color formation is to locally coat the color de, veloper on the support or the coated layer of the color former without using the desensitizer.
• a color developer composed of a polymer of an aromatic carboxylic acid having at least onehydroxyl group or its anhydride with an aldehyde or acetylene and a metallic compound is far stronger in color developing ability than only a polymer of an aromatic carboxylic acid having at least one bydroxyl group with aldehyde or acetylene or its anhydride, or only a metallic compound, and that the color formed or the color former sheet is stronger in light resistance.
• color developers such as phenolaldehyde polymers,phenol-acetylenepolymers, maleic acid-rosin polymers, partially-or all hydrolyzed styrenemaleicanhydride polymers, etc.
• one feature of the present invention is to use a polymer of aromatic carboxylic acid having at least one hydroxyl group with an aldehyde or an acetylene.
• metallic oxides metallic hydroxides and metallic carbonates, etc.
• a metallic oxide an oxide of a metal belonging to group Ila of the Periodic Table, such as magnesium oxide, calcium oxide, barium oxide, etc., an oxide of a metal belonging to group llb of the Periodic Table, such as zinc oxide, cadmium oxide, mercury oxide, etc., an oxide of a metal belonging to group Illa of the Periodic Table, such as aluminum oxide, etc., and an oxide of a metal belonging to group lVa of the Periodic Table, such as tin oxide, lead oxide, etc., are particularly effective.
• a hydroxide of a metal belonging to group Ila of the Periodic Table such as magnesium hydroxide, calcium hydroxide, etc.
• a hydroxide of a metal belonging to group llb of the Periodic Table such as zinc hydroxide, cadmium hydroxide, mercury hydroxide, etc.
• a hydroxide of a metal belonging to group lIIa of the Periodic Table such as aluminum hydroxide, etc.
• a hydroxide of a metal belonging to group IVa of the Periodic Table such as tin hydroxide, lead hydroxide, etc.
• a carbonate of metal belonging to group lla of the Periodic Table such as magnesium carbonate, calcium carbonate, etc.
• a carbonate of metal belonging to group Ilb of the Periodic Table such as zinc carbonate, cadmium carbonate, etc.
• a carbonate of metal belonging to group IVa of the Periodic Table such as lead carbonate, etc.
• metallic compounds zinc oxide, cadmium oxide, magnesium oxide, zinc hydroxide, magnesium hydroxide, calcium hydroxide, zinc hydroxide, magnesium hydroxide, calcium hydroxide, zinc carbonate, calcium carbonate, magnesium carbonate, etc., are particularly effective for an aromatic carboxylic acid having at least one hydroxyl group. More particularly, oxides or carbonates of zinc are effective.
• the metallic compound may be crushed and converted in size so as to pass a sieve of more than 325 mesh.
• the ratio of the metallic compound and the polymer is more than one part by weight of the polymer, preferably -30 parts by weight based on 100 parts by weight of metallic compound, desirably 2-100 parts by weight.
• a pigment may be added to the color developer.
• the pigment contains aluminum silicate, zinc silicate, lead silicate, tin silicate, colloidal hydrated aluminum silicate, zeolite, bentonite, laolinite, active clay, acid clay, talc and the like.
• the amount of pigment does not have a critical value.
• more than one part by weight, preferably 10-500 parts by weight per 100 parts by weight of the polymer can be employed.
• the color developer of the invention can be prepared by dissolving or dispersing the polymer and the metallic compound in water or in an organic solvent such as methanol, ethanol, butanol, ethyl acetate, butyl acetate, benzene, toluene, acetone, tetrahydrofuran or methylene chloride.
• Water and the organic solvent may be mixed.
• the solvent is capable of dissolving the polymer.
• it may be dispersed in water, in the organic solvent, in the solution or in the dispersion.
• the thus-prepared solution or dispersion can be coated onto a support, if necessary, together with a binder such as gum arabic, ethyl cellulose, styrenebutadiene copolymer, nitrocellulose, styrene-butadiene latex, methylmethacrylate-butadiene latex, etc.
• a binder such as gum arabic, ethyl cellulose, styrenebutadiene copolymer, nitrocellulose, styrene-butadiene latex, methylmethacrylate-butadiene latex, etc.
• the'coated layer of color developer can be maintained on the support even if the binder is not present in the layer.
• the amount of the color developer coating composition is not specifically limited to obtain sufficient color. For example, it is more than 0.1 g/m"', preferably 0.5-10 g/m.
• the upper limit of coating amount is not limited from the point of view of color developing activity, and the above range is only due to economic reasons.
• the color developer composition can be coated onto a support by all kinds of coating methods, because the present invention is basically characterized by using the polymer and the metallic compound.
• the metallic compound and, if necessary, the pigment may be coated onto the support with the binder, and then the dissolved or dispersed polymer may be coated thereon.
• the binder is dissolved in the organic solvent and a plasticizer is added and then both the polymer and the metallic compound are dissolved or dispersed in the resulting solution.
• the plasticizer may contain esters of phosphoric acid, phthalic acid, adipic acid or sebacic acid (e.g., tributyl phosphate, dibutyl phthalate, dioctyl phthalate, butyl adipate, dibutyl sebacate), hydrocarbon such as chlorinated paraffin, and glycerides of unsaturated fatty acids such as castor oil.
• esters of phosphoric acid, phthalic acid, adipic acid or sebacic acid e.g., tributyl phosphate, dibutyl phthalate, dioctyl phthalate, butyl adipate, dibutyl sebacate
• hydrocarbon such as chlorinated paraffin
• glycerides of unsaturated fatty acids such as castor oil.
• an alkali metal salt of an organic acid may be added to the composition.
• the alkali metal salt of an organic acid is, for example, a lithium salt, a sodium salt or a potassium salt of butylic acid, caprylic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, and the like.
• the alkali may be, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, borax and conventional alkali compounds.
• the amount of the alkali is 0.01-1 part by weight per one part by weight of the polymer.
• the thus-prepared color developer ink can be locally applied to a support.
• a color developer sheet and the color developer of the invention can be used in combination with conventional color former such as crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone, rhodamine B lactam, fluoranes (US. Pat. Nos. 3,501,331, 3,514,310, 3,514,311, 3,540,911), spiropyrans (US. Pat. No. 3,293,060), mixtures thereof, and the like.
• conventional color former such as crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone, rhodamine B lactam, fluoranes (US. Pat. Nos. 3,501,331, 3,514,310, 3,514,311, 3,540,911), spiropyrans (US. Pat. No. 3,293,060), mixtures thereof, and the like.
• the color formers for pressure-sensitive copying paper are ordinarily employed in combination in order to secure the instantaneous color-forming property and light fastness of the colored image.
• a combination of instantaneous color-forming crystal violet lactone as a primary color former and benzoyl leucomethylene blue having excellent light fastness has been most well known; however, the colored image obtained by contacting the combination of color formers with an aromatic carboxylic acid or its anhydride tends to disappear when it is allowed to stand in a room or is exposed to sunlight, since crystal violet fades before benzoyl leucomethylene blue is color formed.
• the color developer sheet of the present invention has the following advantages: v
• the conventional clay-coated paper tends to be decreased in sensitivity of clay, when being allowed to stand in air, because of adsorbing materials in air on the active point of the clay. That is, the color developing ability of the color developer sheet is remarkably lowered with time.
• the color developer sheet of the present invention such defect has been improved. And, in case of manufacturing a color developer sheet in accordance with the present invention, sufficient color developing abil ity and other properties necessary to the color developer sheet for pressure-sensitive paper can be satisfied with smaller coating amounts than in the conventional clay paper. That is, the amount of color developer of the present invention to be coated is sufiicient with 0.1-4 g/m while in the conventional clay paper the amount to be coated is 7-10 g/m. Thus, it is possible to make the color developer sheet by a size spray coating by means of a machine because only a small amount is required and the physical properties of the liquid can be freely varied different from clay, which results in a remarkable effect not only on performance but also on production.
• the color formed on the clay-coated paper is easily caused to disappear or to be lowered in density when wetted with water
• the color formed on the color developer sheet of the present invention has such an excellent property that the color density is not lowered even in case of being wetted with water.
• the color developer of the present invention can give the similar color developing ability with smaller amounts (about 2 g/m if a natural or synthetic high molecular weight substance or a waterrepellent material is previously coated on the surface of paper.
• Microcapsules containing a color former were manufactured, for example, according to the specification of U. S. Pat. No. 2,800,457, as follows:
• the color former oil is 2 percent of crystal violet lac- 3-dibenzylamino-7-diethylaminofluorane dissolved in an oil consisting of 4 parts by weight of chlorinated diphenyl and one part by weight of kerosene.
• the emulsification was stopped when the size of the oil droplets became 5 microns on an average.
• Water at 40 C was added thereto to 900 parts by total weight and the stirring was continued. At this time attention must be paid so that the liquid temperature does not decrease to below 40 C.
• 10 percent acetic acid was added thereto to adjust the pH of the system to 4.0 to 4.2 and to cause coacervation.
• microcapsules thus obtained were conditioned to 30 C and thereafter were coated onto a 40 g/m paper in 6 g/m as a solid content and dried. Also in case of other color formers, the recording paper was manufactured in the same manner as described above.
• part means part by weight.
• Example 1 138 parts of salicylic acid and 325 parts of 37 percent formaldehyde were polymerized by adding 250 parts of 12 N sulfuric acid as a catalyst thereto and heating at --97 C for l hour. After dissolving or dispersing 20 parts of the resulting polymer (P-l and 10 parts of one of the below described binders in 300 parts of one of the below described solvents, parts of one of the below described metallic compounds passing a sieve of 325 mesh were dispersed therein under stirring. The resulting coating was coated onto a 40 g/m paper so as to give a solid content of 5 g/m and dried.
• Comparative Example lb 20 parts of the polymer (P-l) polymerized by the method of Example 1 and 1.7 part of one of the below described binders were dissolved or dispersed in one of the below described solvents and the resulting coating was coated onto a 40 g/m paper in an amount of 0.78 g/m Comparative Example la I00 parts of one of the below described metallic salts passing a sieve of 325 mesh was dispersed in one of the below described solvents and, in addition, 8.3 parts of one of the below described binders was dissolved or dispersed therein. The resulting coating was coated onto a 40 g/m paper in a solid content of 4.2 g/m and dried.
• Comparative Example 2a 100 parts of one of the below described metallic salts passing a sieve of 325 mesh was dispersed in one of the The results of (l) and (2) are as shown in Table l. 5 below described solvents and, in addition, 7.7 parts of TABLE 1 Color density of Colordensity of 3-dibenzylamino crystal violet 7-diethyl- Class Polymer Metallic compound Solvent Binder lactone amino'fluorane
• Examplel p-l Zinc carbonate Ethanol Ethyl cellulose 0.962 0.893 Comparative example l-a. o d
• Example I Zinc hydrozide.. Comparative example I do Example 1 alcium carbonate Comparative example l-a.. ..do
• Example I Comparative example la.. o
• Example 1 p-l Aluminum ..do ..do 0.590
• Comparative example 1-a ..do ..do ..do not color not color.
• Comparative example l-a ..do ..do ..do not color... not color. Comparative example l-b p-l ..do ..do 0.221 0.292.
• the color developer sheet of the present invention was higher in color developing ability, and thev color image formed on the present color developer sheet was not lowered in color density even in the case of being wetted with water.
• Example 2 154 parts of 2,6-dihydroxybenzoic acid and 325 parts of 37 percent formaldehyde were polymerized by adding 250 parts of 12 N sulfuric acid as a catalyst thereto and heating at 95-97 C for 1 hour. After dissolving or dispersing 30 parts of the resulting polymer (P-2) and parts of one of the below described binders in 300 parts of one of the below described solvents, 100 parts of one of the below described metallic compounds passing a sieve of 325 mesh were dispersed therein under stirring. The resulting coating was coated onto a 40 g/m paper in a solid content of 5 g/m and dried.
• binders one of the below described binders was dissolved or dispersed therein.
• the resulting coating was coated onto a 40 g/m paper in a solid content of 3.8 g/m and dried.
• Example 3 250 parts of 12 N sulfuric acid were added to 138 parts of salicylic acid and 325 parts of 37 percent formaldehyde and were heated and stirred at 95-97 C for l hour. After dissolving or dispersing 40 parts of the above prepared polymer (P-l) and parts of the below described binder in 300 ml of the below described solvent, 30 parts of the below described metallic compound passed through a sieve of 325 mesh and 30 parts of the below described inorganic pigment were added thereto while stirring. This coating liquid was coated onto a 40 g/m paper by means of a coating rod with a solid content of 4.5 g/m and dried.
• Comparative Example 3 After dissolving or dispersing 40 parts of polymer polymerized by the method of Example 3 and 0.7 parts of the below described binder in 300 ml of the below described solvent, 30 parts of the below described metallic compound which passes through a sieve of 325 mesh were added thereto while stirring. This coating liquid was coated onto a 40 g/m paper by means of a coating rod in .a solid content of 3.5 g/m and dried.
• Comparative Example 4 Using the polymer prepared by the method of Example 4, a color developer sheet for comparison was obtained in the same manner as in Comparative Example 3.
• the color developer sheet of the present invention that is, a color developer sheet having combined a polymer, a metallic compound and an inorganic pigment, is more excellent in comparison with that having combined a polymer and a metallic compound.
• the color images formed on the color developer sheet of the present invention did not disappear even in the case of wetting with water.
• Example 5 138 parts of salicylic acid and 325 parts of 37 percent Table 5 Varnish Polymer (P-l) Metallic compound Pigment No. (parts) (parts) (parts) (parts) I 67 8 25 (zinc oxide) 2 70 i 20 (calcium oxide) 3 72 8 15 (aluminum (organic hydroxide) bentonite) 154 parts of 2,6-dihydroxybenzoic acid and 325 parts of 37 percent formaldehyde were polymerized by adding 250 parts of 12 N sulfuric acid thereto under heating at 95-97 C for 1 hour to obtain a polymer (P-2).
• Varnish B A solution (hereinafter referred to as Varnish B) was prepared by mixing parts of nitrocellulose, 30 parts of butyl acetate, 40 parts of ethyl alcohol and parts of methyl cellulosolve. To the solution, the polymer (P-2) and the additives shown in Table 6 were added by means of a ball mill to provide a color developer ink.
• Varnish Polymer B (P-2) Metallic compound Pigment No. (parts) (parts) (parts) (parts) 4 65 I0 (zinc carbonate) 5 66 l0 19 (basic aluminum 5 (kaolinacetate) ite) diluted with a solvent shown in the following Table 7 so as to be a viscosity of about centipoise, and then was applied to a paper in a dry thickness of 2 g/m by flexo or'gravure printing method. The thus-obtained color developer sheets were placed on a color former sheet (crystal violet lactone or 3-dibenzylamino-7- diethylamino fluorane) and pressurized under 600 kg/m to form color images.
• a color former sheet crystal violet lactone or 3-dibenzylamino-7- diethylamino fluorane
• the color developer ink of the invention gives a more excellent color developing ability even in case of thin coatings (2 glm Furthermore, even if the color images were wetted with water, the color density was not lowered.
• a recording sheet comprising, in combination with a color former which comprises a colorless dye-forming organic compound, a support having coated thereon a layer of a color developer containing a combination of (i) a polymer of (a) an aromatic carboxylic acid or (b) its anhydride with an aldehyde or acetylene, said polymer having at least one hydroxyl group, and (ii) a metallic compound selected from the group consisting of a metal oxide, a metal hydroxide and a metal carbonate, said color developer being capable of forming a distinct color when contacted with said color former, the amount of said polymer being at least one part by weight based on l00parts by weight of said metallic aqan.
• a recording sheet of claim 1 wherein said metal is selected from the group consisting of metals of groups Ila, lib, Illa and IVa of the Periodic Table.
• said metallic compound is selected from the group consisting of zinc oxide, cadmium oxide, magnesium oxide, zinc hydroxide, magnesium hydroxide, calcium hydroxide,
• the recording sheet of claim 1 further consisting essentially of an alkali metal salt of an organic acid or an alkali compound in an amount of from 0.01 to 1 part by weight per 1 part by weight of said polymer.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Color Printing (AREA)

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• 1971
  • 1971-09-27 GB GB4499471A patent/GB1330984A/en not_active Expired
  • 1971-09-28 CA CA123,827A patent/CA945759A/en not_active Expired
  • 1971-09-28 DE DE2148427A patent/DE2148427B2/de active Pending
  • 1971-09-28 FR FR7134890A patent/FR2108651A5/fr not_active Expired
  • 1971-09-28 BE BE773190A patent/BE773190A/xx not_active IP Right Cessation
  • 1971-09-28 US US3767449D patent/US3767449A/en not_active Expired - Lifetime
  • 1971-10-20 AU AU34782/71A patent/AU463285B2/en not_active Expired
  • 1971-10-21 CA CA125,693A patent/CA947075A/en not_active Expired
  • 1971-10-22 GB GB4931671A patent/GB1364736A/en not_active Expired
  • 1971-10-22 DE DE2152763A patent/DE2152763C3/de not_active Expired
  • 1971-10-25 BE BE774439A patent/BE774439A/xx not_active IP Right Cessation
  • 1971-10-25 FR FR7138307A patent/FR2113223A5/fr not_active Expired
  • 1971-10-26 US US3772052D patent/US3772052A/en not_active Expired - Lifetime

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