GB1417442A - Method of making magnetic recording materials and materials made thereby - Google Patents

Method of making magnetic recording materials and materials made thereby

Info

Publication number
GB1417442A
GB1417442A GB873273A GB873273A GB1417442A GB 1417442 A GB1417442 A GB 1417442A GB 873273 A GB873273 A GB 873273A GB 873273 A GB873273 A GB 873273A GB 1417442 A GB1417442 A GB 1417442A
Authority
GB
United Kingdom
Prior art keywords
magnetic
viscous
layers
vinylidene chloride
support
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB873273A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Publication of GB1417442A publication Critical patent/GB1417442A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/007—Slide-hopper coaters, i.e. apparatus in which the liquid or other fluent material flows freely on an inclined surface before contacting the work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/305—Extrusion nozzles or dies having a wide opening, e.g. for forming sheets
    • B29C48/307—Extrusion nozzles or dies having a wide opening, e.g. for forming sheets specially adapted for bringing together components, e.g. melts within the die
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/911—Cooling
    • B29C48/9135—Cooling of flat articles, e.g. using specially adapted supporting means
    • B29C48/914—Cooling of flat articles, e.g. using specially adapted supporting means cooling drums
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/702—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the bonding agent
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/716—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by two or more magnetic layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/842—Coating a support with a liquid magnetic dispersion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
    • B05C9/06—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying two different liquids or other fluent materials, or the same liquid or other fluent material twice, to the same side of the work
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor
    • G03C2001/7481—Coating simultaneously multiple layers

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Dispersion Chemistry (AREA)
  • Paints Or Removers (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Magnetic Record Carriers (AREA)
  • Laminated Bodies (AREA)

Abstract

1417442 Magnetic recording materials EASTMAN KODAK CO 22 Feb 1973 [24 Feb 1972 9 Feb 1973] 8732/73 Heading B2E A method of making a magnetic recording material (e.g. a flexible disc, belt, sheet or tape) comprises coating a non-magnetisable support with two superimposed layers of viscous liquid-containing magnetic coating compositions and then causing the layers to solidify. A less viscous subbing coating may be present between the support and the magnetic coatings and may comprise a viscous solution of polyvinylbutyral or copolymers of: vinylidene chloride/acrylonitrile; vinyl acetate/ vinyl chloride partially hydrolised and optionally cross linked with a isocyanate; or vinylidene chloride/acrylonitrile/acrylic acid. The viscous magnetic coating compositions may comprise 'the anisotropic magnetic particles of different coercivities, but the same material in a solution of a binder which may be the same in both layers. The magnetic material is typically ferromagnetic iron oxide (e.g. magnetite or gamma ferric oxide), complex oxides of iron and cobalt, chromium dioxide, ferrites, or magnetic metal alloys. Preferred is acicular gamma ferric oxide which is doped with a polyvalent metal such as Co, Ni, Zn, Mn or Cr. Useful binders are: polyvinylbutyral; polyesters e.g. polyethylene terephthalate: polyurethanes; or copolymers of vinyl acetate/vinyl chloride, vinylidene chloride/acrylonitrile, acrylic/methacrylic esters, butadiene/styrene, vinylidene chloride/maleic or maleamid anhydride, cross linked or not cross linked; or mixtures thereof. The binder solution may also contain conventional additives, carbon for conductivity to avoid static and colloidal silica being mentioned. To apply the coatings the viscous magnetic coatings are cast on a layer of the less subbing layer. The layers then slide down a chute Imbricated by the less viscous subbing layer onto a support. Suitable film tape support material is cellulose nitrate or acetate, polyvinyl acetal, polystyrene, polycarbonate, or polyester such as polyethylene terephthalate, and may be biaxially or asymmetrically stretched. Other materials such as paper or metals (e.g. aluminium or brass) may be used.
GB873273A 1972-02-24 1973-02-22 Method of making magnetic recording materials and materials made thereby Expired GB1417442A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7206203A FR2172838B1 (en) 1972-02-24 1972-02-24
FR7304704A FR2217758B1 (en) 1972-02-24 1973-02-09

Publications (1)

Publication Number Publication Date
GB1417442A true GB1417442A (en) 1975-12-10

Family

ID=26216929

Family Applications (2)

Application Number Title Priority Date Filing Date
GB873273A Expired GB1417442A (en) 1972-02-24 1973-02-22 Method of making magnetic recording materials and materials made thereby
GB873173A Expired GB1417765A (en) 1972-02-24 1973-02-22

Family Applications After (1)

Application Number Title Priority Date Filing Date
GB873173A Expired GB1417765A (en) 1972-02-24 1973-02-22

Country Status (8)

Country Link
JP (1) JPS5612937B2 (en)
BE (1) BE795896A (en)
CA (1) CA1048865A (en)
DE (2) DE2309159A1 (en)
FR (2) FR2172838B1 (en)
GB (2) GB1417442A (en)
IT (1) IT979420B (en)
NL (2) NL7302674A (en)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6070519A (en) * 1983-09-28 1985-04-22 Fuji Photo Film Co Ltd Magnetic recording medium
US5756148A (en) * 1991-01-21 1998-05-26 Fuji Photo Film Co., Ltd. Magnetic recording medium
EP0838267A3 (en) * 1996-07-30 1998-06-03 Eastman Kodak Company Improved high speed coating starts using a shear thinning top layer
US5827600A (en) 1991-01-21 1998-10-27 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6096406A (en) 1997-07-15 2000-08-01 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6203934B1 (en) 1997-10-14 2001-03-20 Fui Photo Film Co., Ltd. Magnetic recording medium
US6254964B1 (en) 1997-02-10 2001-07-03 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6291052B1 (en) 1997-06-30 2001-09-18 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6316077B1 (en) 1998-06-22 2001-11-13 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6432503B2 (en) 1997-03-31 2002-08-13 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6444290B1 (en) 1998-06-11 2002-09-03 Fuji Photo Film Co., Ltd. Magnetic recording medium comprising a support containing a specific size filler and having a specific concentration of surface protrusions
US6579592B1 (en) 1996-11-29 2003-06-17 Fuji Photo Film Co., Ltd Magnetic recording tape with controlled Hc and magnetic flux/unit area value and controlled Cl/Fe intensity
US7259935B2 (en) 2002-07-05 2007-08-21 Hitachi Maxell, Ltd. Magnetic tape including an intermediate layer consisting essentially of a binder

Families Citing this family (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1429260A (en) * 1973-10-12 1976-03-24 Ciba Geigy Ag Coating apparatus
JPS5843815B2 (en) * 1975-10-23 1983-09-29 富士写真フイルム株式会社 Jikiki Loc Tape
US4001024A (en) * 1976-03-22 1977-01-04 Eastman Kodak Company Method of multi-layer coating
DE2752895A1 (en) * 1976-12-06 1978-06-08 Emi Ltd METHOD FOR PRODUCING A MATERIAL LAYER, THE SURFACE OF WHICH HAS A SCANABLE PATTERN, AS WELL AS A SECURITY DOCUMENT SYSTEM
US4113903A (en) * 1977-05-27 1978-09-12 Polaroid Corporation Method of multilayer coating
GB2006977B (en) * 1977-10-14 1982-02-24 Eastman Kodak Co Manufacture of coated paper
DE2801452C2 (en) * 1978-01-13 1985-03-28 Agfa-Gevaert Ag, 5090 Leverkusen Magnetic recording material
NL8220324A (en) * 1981-09-28 1983-08-01 Sony Corp MAGNETIC RECORD MEDIUM.
JPS5856228A (en) * 1981-09-28 1983-04-02 Sony Corp Magnetic recording medium
DE3238904A1 (en) * 1982-10-21 1984-04-26 Agfa-Gevaert Ag, 5090 Leverkusen METHOD FOR THE MULTIPLE COATING OF MOVING RAILWAYS
DE3238905C2 (en) * 1982-10-21 1986-01-23 Agfa-Gevaert Ag, 5090 Leverkusen Process for the multiple coating of moving objects or tracks
JPS59172144A (en) * 1983-03-20 1984-09-28 Hitachi Maxell Ltd Magnetic recording medium
JPS59172142A (en) * 1983-03-20 1984-09-28 Hitachi Maxell Ltd Magnetic recording medium
DE3339780A1 (en) * 1983-11-03 1985-05-15 Sandy Hill Corp., Hudson Falls, N.Y. Apparatus for the application of a controllable layer of a saturation or coating medium by means of a free-falling curtain, and process therefor
JPS6292132A (en) * 1985-10-18 1987-04-27 Fuji Photo Film Co Ltd Manufacture of magnetic recording medium
JPS62124631A (en) * 1985-11-26 1987-06-05 Fuji Photo Film Co Ltd Coating method for magnetic recording medium
JPH0690786B2 (en) * 1987-01-30 1994-11-14 富士写真フイルム株式会社 Magnetic recording medium
DE3717882A1 (en) * 1987-05-27 1988-12-08 Basf Ag METHOD FOR THE STRUCTUR-FREE APPLICATION OF DISPERSIONS ON FLEXIBLE CARRIER MATERIALS
JP2581570B2 (en) * 1987-10-19 1997-02-12 富士写真フイルム株式会社 Video magnetic recording media
JP2581569B2 (en) * 1987-10-19 1997-02-12 富士写真フイルム株式会社 Audio tape or video tape
JPH07119594B2 (en) * 1988-07-01 1995-12-20 富士写真フイルム株式会社 Method for measuring film thickness of magnetic recording medium
US5143758A (en) * 1991-03-28 1992-09-01 Eastman Kodak Company Coating by means of a coating hopper with coating slots where the coating composition has a low slot reynolds number
DE69213115T3 (en) † 1991-04-25 2005-05-19 Fuji Photo Film Co., Ltd., Minami-Ashigara Magnetic recording media
JP2566096B2 (en) † 1992-04-14 1996-12-25 富士写真フイルム株式会社 Magnetic recording media
DE4226139A1 (en) * 1992-08-07 1994-02-10 Basf Magnetics Gmbh Coating system for producing a magnetic recording tape - comprises a multi-slot extruder caster arranged to coat a moving film base with a magnetic multilayer which is exposed to a magnetic field
DE4234608C2 (en) * 1992-08-07 1997-08-07 Basf Magnetics Gmbh Process for producing a magnetic recording medium
US5932330A (en) * 1993-09-30 1999-08-03 Imation Corp. Coated magnetic recording medium, paint for coated magnetic medium and method for producing coated magnetic medium
US6030695A (en) * 1996-03-28 2000-02-29 Imation Corp. Coated magnetic recording medium, paint for coated magnetic medium and method for producing coated magnetic medium
JPH10290946A (en) 1997-02-21 1998-11-04 Konica Corp Coating method and coating device
JPH11197576A (en) 1998-01-08 1999-07-27 Konica Corp Coater and coating method

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH131599A (en) * 1927-02-05 1929-02-28 Nuera Art Silk Company Limited Process for the production of cellulosic pellets, tapes and films.
FR1270371A (en) * 1960-10-14 1961-08-25 Philips Nv Process for the manufacture of articles intended for the recording and reproduction of magnetic inscriptions and articles thus manufactured
US3627564A (en) * 1970-07-16 1971-12-14 Eastman Kodak Co Method for coating a continuous web

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0471244B2 (en) * 1983-09-28 1992-11-13 Fuji Photo Film Co Ltd
JPS6070519A (en) * 1983-09-28 1985-04-22 Fuji Photo Film Co Ltd Magnetic recording medium
US5985408A (en) 1991-01-21 1999-11-16 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5756148A (en) * 1991-01-21 1998-05-26 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6025082A (en) 1991-01-21 2000-02-15 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5763046A (en) 1991-01-21 1998-06-09 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6020022A (en) 1991-01-21 2000-02-01 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5795646A (en) * 1991-01-21 1998-08-18 Fuji Photo Film Co. Ltd. Magnetic recording medium
US5811166A (en) 1991-01-21 1998-09-22 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5811172A (en) 1991-01-21 1998-09-22 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5827600A (en) 1991-01-21 1998-10-27 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5851622A (en) 1991-01-21 1998-12-22 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5792543A (en) 1991-04-25 1998-08-11 Fuji Photo Film Co., Ltd. Magnetic recording medium
US5780141A (en) 1991-04-25 1998-07-14 Fuji Photo Film Co., Ltd. Magnetic recording medium
EP0838267A3 (en) * 1996-07-30 1998-06-03 Eastman Kodak Company Improved high speed coating starts using a shear thinning top layer
US6579592B1 (en) 1996-11-29 2003-06-17 Fuji Photo Film Co., Ltd Magnetic recording tape with controlled Hc and magnetic flux/unit area value and controlled Cl/Fe intensity
US6254964B1 (en) 1997-02-10 2001-07-03 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6432503B2 (en) 1997-03-31 2002-08-13 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6291052B1 (en) 1997-06-30 2001-09-18 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6096406A (en) 1997-07-15 2000-08-01 Fuji Photo Film Co., Ltd. Magnetic recording medium
US6203934B1 (en) 1997-10-14 2001-03-20 Fui Photo Film Co., Ltd. Magnetic recording medium
US6444290B1 (en) 1998-06-11 2002-09-03 Fuji Photo Film Co., Ltd. Magnetic recording medium comprising a support containing a specific size filler and having a specific concentration of surface protrusions
US6316077B1 (en) 1998-06-22 2001-11-13 Fuji Photo Film Co., Ltd. Magnetic recording medium
US7259935B2 (en) 2002-07-05 2007-08-21 Hitachi Maxell, Ltd. Magnetic tape including an intermediate layer consisting essentially of a binder

Also Published As

Publication number Publication date
JPS4898803A (en) 1973-12-14
CA1048865A (en) 1979-02-20
FR2172838B1 (en) 1975-10-24
JPS5612937B2 (en) 1981-03-25
DE2309158A1 (en) 1973-09-13
DE2309158B2 (en) 1974-05-02
DE2309158C3 (en) 1981-06-11
FR2172838A1 (en) 1973-10-05
DE2309159A1 (en) 1973-08-30
FR2217758A1 (en) 1974-09-06
BE795896A (en) 1973-08-23
IT979420B (en) 1974-09-30
NL7302674A (en) 1973-08-28
GB1417765A (en) 1975-12-17
NL7302673A (en) 1973-08-28
FR2217758B1 (en) 1976-11-05

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
433D Application made for revocation (sect. 33/1949)
433C Case decided by the comptroller ** specification amended (sect. 33/1949)
SPA Amended specification published
PCNP Patent ceased through non-payment of renewal fee