WO1997037252A1 - Structure retroreflechissante a couleur persistante - Google Patents

Structure retroreflechissante a couleur persistante Download PDF

Info

Publication number
WO1997037252A1
WO1997037252A1 PCT/US1997/004890 US9704890W WO9737252A1 WO 1997037252 A1 WO1997037252 A1 WO 1997037252A1 US 9704890 W US9704890 W US 9704890W WO 9737252 A1 WO9737252 A1 WO 9737252A1
Authority
WO
WIPO (PCT)
Prior art keywords
retroreflective
fluorescent
layer
transparent
array
Prior art date
Application number
PCT/US1997/004890
Other languages
English (en)
Inventor
David C. Martin
Original Assignee
Reflexite Corporation
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 Reflexite Corporation filed Critical Reflexite Corporation
Publication of WO1997037252A1 publication Critical patent/WO1997037252A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/122—Reflex reflectors cube corner, trihedral or triple reflector type
    • G02B5/124—Reflex reflectors cube corner, trihedral or triple reflector type plural reflecting elements forming part of a unitary plate or sheet

Definitions

  • Retroreflective materials are employed for various safety purposes, such as traffic signs. These materials are particularly useful at nighttime when visibility is critical under low light conditions. However, these materials are exposed during daylight hours to harsh ultraviolet light emitted by the sun, which over time can cause deterioration of the materials with a subsequent loss of brightness, color and contrast. Retroreflective materials are typically formed of a sheet of thermoplastic, which has a colorant mixed therein with the polymers. Attached to the sheet of thermoplastic is an array of cube-corner or prismatic retroreflectors as described in U.S. Patent 3,712,706, issued to Stamm on January 23, 1973. Generally, the prisms are made by forming a master die on a flat surface of a metal plate or other suitable material .
  • the cube-corner To form the cube-corner, three series of parallel equidistant intersecting V-shaped grooves 60 degrees apart are inscribed in the plate. The die is then used to process the desired cube-corner array into a flat plastic surface. When the groove angle is 70 degrees, 31 minutes, 43.6 seconds, the angle formed by the intersection of two cube faces (dihedral angle) is 90 degrees and the incident light is retroreflected back to the source.
  • the efficiency of a retroreflective structure is the measure of the amount of incident light returned within a cone diverging from the axis of retroreflection. A distortion of the prismatic structure adversely affects the efficiency.
  • cube-corner retroreflective elements have low angularity at some orientation angles, for instance, the elements will only brightly reflect light that impinges on it within a narrow angular range centering approximately on its optical axis. Low angularity arises from the inherent nature of these elements which are trihedral structures having three mutually perpendicular lateral faces.
  • the elements are arranged so that the light to be retroreflected impinges into the internal space defined by the faces, and the retroreflection of the impinging light occurs by internal retroreflection of the light from face to face of the element .
  • Impinging light that is inclined substantially away from the optical axis of the element (which is a trisection of the internal space defined by the faces of the element) strikes the face at an angle less than its critical angle, thereby passing through the face rather than being reflected.
  • a method for making retroreflective sheeting is also disclosed in U.S. Patent 3,689,346, issued to Rowland on September 5, 1972.
  • the disclosed method is for forming cube-corner microprisms in a cooperatively configured mold.
  • the prisms are bonded to sheeting which is applied thereover to provide a composite structure in which cube-corner microprisms project from one surface of the sheeting.
  • a problem with fluorescent retroreflective sheeting, such as fluorescent orange roll-up signs that are made from a single layer of colored sheeting, is that the colorant of the transparent fluorescent vinyl window material is gradually consumed with lengthy exposure to ultraviolet light emitted by the sun.
  • the transparent orange vinyl fades to a yellowish clear film, but the retroreflective prism structure continues to function.
  • the original color degrades within a short period of time. This time can be anywhere from about three to twelve months in some cases.
  • the present invention relates to a fluorescent retroreflective structure formed of a layered structure comprised of a transparent fluorescent thermoplastic layer and a transparent non-fluorescent thermoplastic layer that is bonded to the transparent fluorescent thermoplastic layer.
  • An array of retroreflective elements is bonded to the layered structure.
  • a backing layer is bonded to the array of retroreflective elements .
  • the transparent non- fluorescent layer includes a non-fluorescent colorant
  • the transparent fluorescent layer includes a fluorescent colorant. Both colorants have essentially the same color coordinates and the non-fluorescent colorant is significantly more stable to degradation when exposed to ultraviolet light than the fluorescent colorant.
  • the present invention also relates to a method for forming a fluorescent retroreflective structure.
  • the steps include bonding a transparent fluorescent thermoplastic layer to a transparent non-fluorescent thermoplastic layer to form a layered structure.
  • An array of retroreflective elements is bonded to the layered structure.
  • a backing layer is bonded to the array of retroreflective elements, thereby forming a retroreflective structure.
  • This invention includes many advantages.
  • One advantage is that a color-fast product or a sheeting can be formed that has one surface that can be truly fluorescent and a second surface that can be formed of a more ultraviolet light stable colorant.
  • Another advantage is if a less fluorescent surface is required, the non-fluorescent color thermoplastic layer is used as the first surface and the array of retroreflective elements is placed against the fluorescent thermoplastic layer.
  • the result of using this structure is the ability to obtain a daytime color that does not possess as a high degree of fluorescence but does fluoresce.
  • the invention can be used in temporary road signs.
  • Figure 1 is a cross-sectional view of a first embodiment of a retroreflective structure of the present invention.
  • Figure 2 is a cross-sectional view of a second embodiment of the retroreflective structure of the present invention.
  • Figure 3 is a chart of the results of outdoor weathering color tests of samples of the present invention having a fluorescent layer and non-fluorescent layer.
  • Figure 4 is a chart of the results of outdoor weathering color tests of samples of a single layer fluorescent sheet.
  • Retroreflective structure 10 is formed of a top layer 12 comprised of an outer fluorescent layer 14 having a fluorescent colorant within it and a non- fluorescent layer 16 having a non-fluorescent colorant within it that is significantly more stable, for example, less susceptible to color deterioration, when exposed to ultraviolet light than the fluorescent colorant contained in the fluorescent layer 14.
  • the retroreflective array 18 can be formed by casting the prisms on the non-fluorescent layer 16 of top layer 12 and can retroreflect impinging light.
  • a bottom layer 26 is attached by welding to top layer 12 through retroreflective array 18 to form a cover layer over the prism array.
  • Welding can be by heat, infrared, ultrasonic or other suitable means known in the art.
  • fluorescent layer 14 and non-fluorescent layer 16 can be reversed with the non-fluorescent layer on the outside.
  • the fluorescent layer 14 is bonded to the non- fluorescent layer 16 by a suitable means, such as fusing, an adhesive, etc.
  • Fluorescent layer 14 is composed of a polymer, which is transparent to visible light.
  • the thermoplastic can be substantially flexible, and sheets of the thermoplastic can be rolled.
  • the polymer can comprise a vinyl thermoplastic film, such as polyvinyl chloride, polyvinylidene chloride, etc.
  • the polymer of fluorescent layer 14 includes a colorant that has a color, such as orange, yellow, lime green, etc. In a preferred embodiment, the fluorescent layer is orange in color. Suitable colorants include dyes available that have a fluorescent color and are reasonably stable to prolonged exposure to ultraviolet light.
  • Stability is considered maintaining color coordinates within a given color boundary, such as that described by the ASTM D4956-94 specification, for a period of six months to two years depending on the type of outdoor exposure. Prolonged exposure is considered a year or more under normal traffic sign usage. Fluorescence is considered the emission of radiation in the visible range as a result of absorption of radiation at a shorter wavelength than the wavelength emitted.
  • a suitable transparent fluorescent film of polyvinyl chloride film is available from the American Renolit Corporation of
  • the fluorescent layer 14 can have a thickness in the range of between about 0.002 and 0.01 inches. In a preferred embodiment, the thickness is in the range of between about 0.005 and 0.007 inches. The selected thickness is dependent upon the method of fabrication, the thermoplastic selected and the characteristics desired for the retroreflective structure.
  • the non-fluorescent layer 16 can be comprised of the same polymer material as the fluorescent layer 14 and bonded thereto. However, the non-fluorescent layer 16 has a non-fluorescent colorant instead of a fluorescent colorant .
  • a suitable transparent non- fluorescent film of polyvinyl chloride film is available from the American Renolit Corporation under the name H- 1W Renolit Clear, Tinted Orange #22010 with Cyasorb.
  • the non-fluorescent colorant is significantly more stable or not as easily decomposed or otherwise modified chemically upon prolonged exposure to ultraviolet light than a fluorescent colorant.
  • minimal movement in color coordinates shows color stability.
  • the orange fluorescent colorant can fade to white (out of the color box) after approximately 48 hours in a carbon-arc weatherometer while the non-fluorescent orange colorant can still be in the color box after five hundred hours of exposure.
  • the color box coordinates are disclosed in ASTM D4956-95, Table 10 for Color Specification Limits (Daytime) for white, yellow, orange, green, red, blue and brown.
  • the fluorescent colorant and the non-fluorescent colorant can have essentially the same color according to color meter tests.
  • Spectrophotometer or colorimeter having 45°/0° or 0°/45° illumination and viewing geometry is suitable for measuring the color.
  • Color coordinates are defined by tristimulus coordinates corresponding to the CIE 1931 Standard Colorimetric System by standard illuminant C.
  • the retroreflective array 18 includes optical elements that are known in the art, such as cube-corner prisms, four-sided prisms, Fresnel lenses, glass beads, rounded lenses, etc.
  • retroreflective array 18 has a window side 20 and facet side 22.
  • the retroreflective array 18 can be formed of a transparent polymer that can be selected from a wide variety of polymers that include the polymers of urethane, acrylic ethers, hard epoxy acrylates, etc.
  • Other polymers include polycarbonates, polyesters and polyolefins, acrylated silanes and urethane acrylates.
  • Other types of polymers that are flexible can include polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene or any other type of flexible thermoplastic.
  • the polymer is cast in a mold with a monomer or oligomer, and the polymerization is initiated by ultraviolet radiation.
  • the retroreflective array 18 is formed of cube-corner prism elements having a length along each cube side edge in the range of between about 0.003 and 0.006 inches. In one embodiment, each cube-side edge has a length of about 0.0049 inches.
  • the top layer 12 provides a transparent substrate and a smooth surface upon which retroreflective array 18 is attached.
  • Top layer 12 can be laminated by attaching the retroreflective array 18 with a transparent adhesive.
  • the adhesive should be plasticizer resistant, because plasticizers can degrade many adhesives.
  • top layer 12 can be fused to retroreflective array 18 by heating top layer 12 and retroreflective array 18 to a temperature near the melting points of the top layer and retroreflective array, thereby allowing the layers to fuse.
  • retroreflective array 18 can be directly cast onto top layer 12 in one step.
  • a sign message can be emblazoned, such as "Men Working", “Stop”, “Caution”, etc.
  • the top layer is orange in color and the lettering is black in color.
  • Bottom layer 26 is Attached to the facet side 22 of the retroreflective array 18 of prismatic elements.
  • Bottom layer 26 is comprised of a thermoplastic which is similarly as flexible as the top layer 12. It can be formed of the same material, such as polyvinyl chloride, polyvinylidene chloride, etc.
  • the bottom layer can be transparent to visible light.
  • the bottom layer 26 is joined to at least a portion of the retroreflective array 18 by high frequency welding, heating or other suitable means at surface 28.
  • the portion of the retroreflective array 18 not joined to the prism array is air backed (not metalized to achieve specular reflection) .
  • the prisms operate according to the principle of total internal reflection when air backed.
  • the weld pattern can be in the form of squares having a side length of between about 0.5 and 1.25 inches.
  • the adhesive can wet the surface of the prisms, thereby destroying the air interface and eliminating the ability of the prism to retroreflect.
  • a retroreflective coating can be deposited on the surface of the dihedral facets.
  • the retroreflective coating 32 is formed by sputtering aluminum, silver or gold or by vacuum metalization.
  • metal lacquers, dielectric coatings and other specular reflecting coating materials can be employed.
  • the retroreflective structure can be formed by various apparatuses and methods that are known in the art .
  • An example of an apparatus and method is disclosed in U.S. Patent 4,244,683, issued to Rowland on January 13, 1981.
  • the retroreflective structure 10 is formed by bonding fluorescent layer 14, such as a polyvinyl chloride, to a non-fluorescent layer 16, thereby forming a top layer 12.
  • the fluorescent layer 14 can be bonded to non-fluorescent layer 12 by fusing, an adhesive or other suitable means.
  • Retroreflective array 18 is formed by casting or other suitable means and is attached on the window side to top layer 12. Retroreflective array 18 can be attached by an adhesive or fusing.
  • the bottom layer 26, formed of a suitable thermoplastic, such as a polyvinyl chloride, is attached to portions of top layer 12 through retroreflective layer 18, such as by radio frequency welding. The remaining portion of the facet side of the retroreflective layer is air backed.
  • bottom layer 26 can be attached to the retroreflective array 18 with an adhesive.
  • a reflective coating 32 is applied prior to attaching the bottom layer 26, to form a specular reflective layer.
  • a series of outdoor weathering tests were conducted under ASTM D4956-94 to compare an embodiment of the present invention (a two-ply product) , a two-ply 0.012 inch laminate of vinyl comprising an orange non- fluorescing outer layer, fused to an orange fluorescent second layer which was tie-coated and upon which cube- corner prisms were cast.
  • This structure was radio frequency welded to a fabric reinforced vinyl backing and compared against a one-ply commercially available orange fluorescent sign product, Reflexite Classic Fluorescent Orange RUS, available from Reflexite Corporation of Avon, Connecticut, and which included a single-ply, 0.010 inch vinyl film comprising an orange fluorescent layer onto which cube-corner prisms were cast.
  • This structure was radio frequency welded onto a fabric reinforced vinyl backing.
  • the tests were conducted in Florida and Arizona where the samples, nine by nine inches in size, were directly exposed to sunlight and oriented to face a southerly direction at a 45° angle to the ground. The samples were exposed for periods of three and six months. Such exposure to sunlight is representative of more than two years of normal use of roll up signs, because the signs typically are not outside all of the time and also are not always facing south. A control not exposed to sunlight was maintained for each sample type.
  • the luminance factor is the ratio the luminance, also known as brightness, of a body when illuminated and observed under certain conditions to that of a perfect diffuser under the same conditions.
  • Luminance is the ratio of the luminous intensity in a given direction of an infinitesimal element of a surface containing the point under consideration, to the orthogonally projected area of the element on a plane perpendicular to the given direction. The brightness of the signs remained reasonably constant in the Florida two-ply test samples.
  • the results of the comparative samples are shown in Figure 4 and in Table 2. After three and six months of direct sunlight exposure, the orange one-ply signs significantly lost their orange color as defined by CIE 1931.
  • the one-ply comparative fluorescent samples turned to a white, non-fluorescent color after six months.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Laminated Bodies (AREA)

Abstract

Cette invention concerne une structure rétroréfléchissante comportant une couche externe constituée d'une première couche de matière plastique transparente contenant un colorant fluorescent et d'une seconde couche de matière plastique transparente contenant un colorant non fluorescent qui est considérablement plus stable à une exposition prolongée au rayonnement ultraviolet que ne l'est le colorant fluorescent. La seconde couche de matière plastique transparente est soudée à la première couche de matière plastique transparente. Un ensemble d'éléments rétroréfléchissants est soudé à la couche supérieure. Une couche interne est soudée à une seconde face de l'ensemble des éléments prismatiques rétroréfléchissants.
PCT/US1997/004890 1996-04-01 1997-03-25 Structure retroreflechissante a couleur persistante WO1997037252A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US62519996A 1996-04-01 1996-04-01
US08/625,199 1996-04-01

Publications (1)

Publication Number Publication Date
WO1997037252A1 true WO1997037252A1 (fr) 1997-10-09

Family

ID=24505000

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/004890 WO1997037252A1 (fr) 1996-04-01 1997-03-25 Structure retroreflechissante a couleur persistante

Country Status (1)

Country Link
WO (1) WO1997037252A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999007944A1 (fr) 1997-08-06 1999-02-18 Reflexite Corporation Systeme portable et compact de panneau de signalisation reflechissant
WO1999048961A2 (fr) * 1998-01-21 1999-09-30 Reflexite Corporation Revetement en polyvinylchlorure fluorescent a duree de vie prolongee
WO2000047407A1 (fr) * 1999-02-12 2000-08-17 Reflexite Corporation Feuille de polychlorure de vinyle dont la duree de fluorescence est prolongee
US6110566A (en) * 1997-10-23 2000-08-29 3M Innovative Properties Company Stabilization of fluorescent dyes in vinyl articles using hindered amine light stabilizers
US6534158B2 (en) * 2001-02-16 2003-03-18 3M Innovative Properties Company Color shifting film with patterned fluorescent and non-fluorescent colorants
WO2004104652A1 (fr) * 2003-05-15 2004-12-02 3M Innovative Properties Company Feuille retroreflechissante, rouge-orange, fluorescente
US9207373B2 (en) 2007-04-10 2015-12-08 Stoncor Group, Inc. Methods for fabrication and highway marking usage of agglomerated retroreflective beads

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766881A (en) * 1973-03-29 1973-10-23 K D Lamp Co Traffic warning device
US3830682A (en) * 1972-11-06 1974-08-20 Rowland Dev Corp Retroreflecting signs and the like with novel day-night coloration
EP0489561A1 (fr) * 1990-12-06 1992-06-10 Minnesota Mining And Manufacturing Company Articles montrant une fluorescence durable
JPH0643819A (ja) * 1992-07-24 1994-02-18 Nippon Carbide Ind Co Inc 視認性のよい再帰反射シート
EP0609880A1 (fr) * 1993-02-05 1994-08-10 Minnesota Mining And Manufacturing Company Rétroréflecteur du type en sommet de cube avec des particules de pigment
WO1995007179A1 (fr) * 1993-09-10 1995-03-16 Reflexite Corporation Structure retroreflechissante resistante au feu

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3830682A (en) * 1972-11-06 1974-08-20 Rowland Dev Corp Retroreflecting signs and the like with novel day-night coloration
US3766881A (en) * 1973-03-29 1973-10-23 K D Lamp Co Traffic warning device
EP0489561A1 (fr) * 1990-12-06 1992-06-10 Minnesota Mining And Manufacturing Company Articles montrant une fluorescence durable
JPH0643819A (ja) * 1992-07-24 1994-02-18 Nippon Carbide Ind Co Inc 視認性のよい再帰反射シート
EP0609880A1 (fr) * 1993-02-05 1994-08-10 Minnesota Mining And Manufacturing Company Rétroréflecteur du type en sommet de cube avec des particules de pigment
WO1995007179A1 (fr) * 1993-09-10 1995-03-16 Reflexite Corporation Structure retroreflechissante resistante au feu

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 018, no. 273 (P - 1742) 24 May 1994 (1994-05-24) *

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999007944A1 (fr) 1997-08-06 1999-02-18 Reflexite Corporation Systeme portable et compact de panneau de signalisation reflechissant
US6115951A (en) * 1997-08-06 2000-09-12 Reflexite Corporation Portable and compact retroreflective sign system
US6406798B2 (en) 1997-10-23 2002-06-18 3M Innovative Properties Company Stabilization of fluorescent dyes in vinyl articles using hindered amine light stabilizers
US7468406B2 (en) 1997-10-23 2008-12-23 3M Innovative Properties Company Stabilization of fluorescent dyes in vinyl articles using hindered amine light stabilizers
US7449514B2 (en) 1997-10-23 2008-11-11 3M Innovative Properties Company Stabilization of fluorescent dyes in vinyl articles using hindered amine light stabilizers
US6526588B2 (en) 1997-10-23 2003-03-04 3M Innovative Properties Company Stabilization of fluorescent dyes in vinyl chloride articles using hindered amine light stabilizers
US6110566A (en) * 1997-10-23 2000-08-29 3M Innovative Properties Company Stabilization of fluorescent dyes in vinyl articles using hindered amine light stabilizers
US6552106B2 (en) 1998-01-21 2003-04-22 Reflexite Corporation Extended life fluorescence polyvinyl chloride sheeting
US6323266B2 (en) 1998-01-21 2001-11-27 Reflexite Corporation Extended life fluorescence polyvinyl chloride sheeting
US6191200B1 (en) 1998-01-21 2001-02-20 Reflexite Corporation Extended life fluorescence polyvinyl chloride sheeting
EP1022128A1 (fr) * 1998-01-21 2000-07-26 Reflexite Corporation Feuille fluorescente en chlorure de polyvinyle à durée de vie prolongée
US6734235B2 (en) 1998-01-21 2004-05-11 Reflexite Corporation Extended life fluorescence polyvinyl chloride sheeting
WO1999048961A3 (fr) * 1998-01-21 2000-01-06 Reflexite Corp Revetement en polyvinylchlorure fluorescent a duree de vie prolongee
WO1999048961A2 (fr) * 1998-01-21 1999-09-30 Reflexite Corporation Revetement en polyvinylchlorure fluorescent a duree de vie prolongee
WO2000047407A1 (fr) * 1999-02-12 2000-08-17 Reflexite Corporation Feuille de polychlorure de vinyle dont la duree de fluorescence est prolongee
US6534158B2 (en) * 2001-02-16 2003-03-18 3M Innovative Properties Company Color shifting film with patterned fluorescent and non-fluorescent colorants
WO2004104652A1 (fr) * 2003-05-15 2004-12-02 3M Innovative Properties Company Feuille retroreflechissante, rouge-orange, fluorescente
US7396579B2 (en) 2003-05-15 2008-07-08 3M Innovative Properties Company Fluorescent red-orange retroreflective sheeting
US9207373B2 (en) 2007-04-10 2015-12-08 Stoncor Group, Inc. Methods for fabrication and highway marking usage of agglomerated retroreflective beads

Similar Documents

Publication Publication Date Title
US6552106B2 (en) Extended life fluorescence polyvinyl chloride sheeting
AU661217B2 (en) Cube-corner retroreflective articles
US3924929A (en) Retro-reflective sheet material
KR100390277B1 (ko) 하나이상의평면에서개선된조사각을형성하는입방체코너물품
US3830682A (en) Retroreflecting signs and the like with novel day-night coloration
EP0333502B1 (fr) Signe rétro-réfléchissante illuminée à l'intérieur
CA2491668C (fr) Panneau indicateur a eclairage interieur
US4349598A (en) High incidence angle retroreflective material
AU665055B2 (en) Retroreflective assembly and process for making same
JP2001290013A (ja) 印刷された再帰反射シート
WO1997037252A1 (fr) Structure retroreflechissante a couleur persistante
JP3221771B2 (ja) キューブコーナー型再帰反射シート
JP4113981B2 (ja) 二方向性再帰反射シート
WO2000047407A1 (fr) Feuille de polychlorure de vinyle dont la duree de fluorescence est prolongee
US3889027A (en) Retroreflective film
KR100968103B1 (ko) 내부 조명 표지
CA1047468A (fr) Materiau en feuilles, a surface retroreflechissante
CN1187246A (zh) 具有不规则基体三角的反光立体角制品
JP2001202041A (ja) 夜光再帰反射シート

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CN JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 97535387

Format of ref document f/p: F

122 Ep: pct application non-entry in european phase