EP0847308A1 - Reverse gravure kiss coating system with output roller - Google Patents

Reverse gravure kiss coating system with output roller

Info

Publication number
EP0847308A1
EP0847308A1 EP96924550A EP96924550A EP0847308A1 EP 0847308 A1 EP0847308 A1 EP 0847308A1 EP 96924550 A EP96924550 A EP 96924550A EP 96924550 A EP96924550 A EP 96924550A EP 0847308 A1 EP0847308 A1 EP 0847308A1
Authority
EP
European Patent Office
Prior art keywords
roller
substrate
gravure
coating
web
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.)
Granted
Application number
EP96924550A
Other languages
German (de)
French (fr)
Other versions
EP0847308B1 (en
Inventor
Gary J. Iafrate
John D. Munter
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.)
3M Co
Original Assignee
Minnesota Mining and Manufacturing 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 Minnesota Mining and Manufacturing Co filed Critical Minnesota Mining and Manufacturing Co
Publication of EP0847308A1 publication Critical patent/EP0847308A1/en
Application granted granted Critical
Publication of EP0847308B1 publication Critical patent/EP0847308B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • 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
    • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
    • B05C1/04—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length
    • B05C1/08—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line
    • B05C1/0839—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line the work being unsupported at the line of contact between the coating roller and the work
    • 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
    • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
    • B05C1/04—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length
    • B05C1/06—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length by rubbing contact, e.g. by brushes, by pads
    • 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
    • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
    • B05C1/04—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length
    • B05C1/08—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line
    • B05C1/0808—Details thereof, e.g. surface characteristics
    • 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
    • B05C1/00—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating
    • B05C1/04—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length
    • B05C1/08—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line
    • B05C1/0826—Apparatus in which liquid or other fluent material is applied to the surface of the work by contact with a member carrying the liquid or other fluent material, e.g. a porous member loaded with a liquid to be applied as a coating for applying liquid or other fluent material to work of indefinite length using a roller or other rotating member which contacts the work along a generating line the work being a web or sheets

Definitions

  • the present invention relates to gravure coating. More particularly, the present invention relates to reverse gravure kiss coating with improved performance.
  • Gravure coating used for producing continuous coatings, uses a gravure roller with depressions or recesses on the surface which control the thickness and uniformity of the coated layer. Ideally the fluid is uniformly "picked out" of the recesses and transferred to the substrate. Typically these recesses are in a regular pattern in the region where a continuous coating is desired.
  • Several styles of gravure coating may be used and designed to enhance individual recess or groove pickout, to transfer coating uniformly, and to optimize other coating responses such as roller surface life, scratching of the substrate, and pattern attenuation.
  • Figure 1 shows a direct gravure coater.
  • the coating fluid 10 is supplied from a pan 12 or other supply such as an extruder-type flow bar to the gravure roller 14.
  • This coating fluid 10 is metered with a doctor blade 16 or roller, and is transferred to a substrate such as a web 18 at a nip point by contacting the web 18 with the fluid in the recesses using a resilient backup roller 20.
  • the gravure roller 14 has etched, machined, or knurled recesses on its surface which can be any shape or size, discontinuous, or continuous over the roller surface.
  • the volume of these recesses controls the average coating thickness, and the specific geometry can be designed to enhance the stability of the pickout from the recesses.
  • the ability to accurately control the volume and shape of these recesses together with the stability of the pickout of a consistent fraction of the fluid in these recesses improves coating thickness uniformity in the downweb and crossweb directions over other coating techniques.
  • the physical characteristics of interest are the average thickness, its uniformity, the presence of discontinuities (such as pinholes and streaks) , and the relative smoothness or initial leveling of the gravure roller pattern upon transfer to the web.
  • the removal of a fraction of the fluid from a recess is the pickout.
  • pickout There are three styles of stable pickout that can occur with transitions between them. Open coating is the transfer of fluid from the recesses individually with no fluid transferred in the region between them. Merged pickout occurs when the material in the recesses merges with the fluid in adjacent recesses to form a continuous coating at the time of transfer. Combined pickout is when the recesses combine together at the time of transfer to form a pattern that is a multiple or fraction of the recess pattern.
  • the volume factor is the internal recess volume per unit area of the gravure roller surface. This controls the average wet coating thickness as a generally constant fraction of the available volume is picked out under similar operating conditions.
  • a flooded inlet is an excess of fluid at the convergence of the web and gravure roller held there by their motion. Whenever a film split occurs in a diverging channel as at the roller exit on a forward roller coater, a natural liquid instability creates machine direction ribs in the coating.
  • a gravure pattern other than the machine directional ribbing When imposing a gravure pattern other than the machine directional ribbing. enhanced individual groove pickout stability can be achieved by matching the frequency of the gravure pattern to the natural liquid ribbing instability frequency in the machine direction.
  • the land/volume factor ratio influences the pickout style.
  • a low land/volume factor ratio encourages merged pickout, and a high ratio promotes open coating.
  • the helix angle is the angle that the grooves in a trihelical pattern make with the gravure roller shaft.
  • Commercially available gravure roller patterns typically have a helix angle of 45°. Smaller helix angles promote pickout instability in forward gravure, and larger angles reduce the width of the pickout transition regions.
  • the internal tooth angle is the angle between the opposing recess walls. Truncation is the flattening of the recess bottom.
  • Web thickness, web tensile modulus, backup roller hardness, and backup roller pressure all influence the average coating thickness because the effective volume factor of the gravure roller is reduced by any penetration of the web into the gravure roller recesses.
  • Increased land widths improve gravure roller wear life. Decreasing land width and increasing the number of recesses enhances recess pattern attenuation at the transfer of the fluid to the web, promoting leveling of the fluid surface.
  • the speed ratio is the ratio of the surface speed of the gravure roller to that of the web.
  • the coating thickness may be changed by changing the speed ratio.
  • the design of the recess pattern for gravure coating influences the stability of the pickout of the fluid from the recesses. Seemingly minor changes in the discussed variables can change the maximum coating speed for stable pickout by hundreds of feet per minute and can affect the ability to achieve significantly thinner wet coatings.
  • misting droplets of fluid spitting from the film split
  • Figure 2 shows a differential speed gravure coater.
  • the web 18 is brought into a controlled engagement with the gravure roller 14 through relatively slight deformation of the backup roller 20 as compared to the high pressure no slip condition with direct gravure coating.
  • the gravure roller 14 and resilient backup roller 20 are driven independently.
  • FIG. 3 shows a reverse gravure coater.
  • the operation of this gravure coater is similar to that of a differential speed coater but the gravure roller surface moves in the opposite direction to the web. Again, the web 18 is brought into a controlled engagement with the gravure roller 14 through position control of the resilient backup roller 20. The gravure roller 14 and backup roller 20 are driven independently. The surface speed of the gravure roller 14 may be above or below web speed. Reverse gravure generally exhibits a larger operating window for acceptable coating than do other gravure coaters.
  • A- Figure 4 shows a gravure kiss coater.
  • the gravure roller 14 may be rotated in either direction, fluid supply and doctoring are not displayed.
  • the operation of this gravure coater is similar to that of a reverse gravure coater but the web 18 is brought into contact with the gravure roller 14 by positioning an input idler roller 22 and output idler roller 24 to create a slight wrap over the gravure roller 14.
  • the surface speed of the gravure roller 14 may be above or below the speed of the web 18. With proper recess design and fluid rheology, fluids which do not totally attenuate the recess pattern upon transfer with other gravure styles may do so with this technique.
  • the web 18 passes between the idler rollers 22, 24 in a free span.
  • This span can be 30 cm, with the gravure roller 14 centered between the idler rollers 22, 24.
  • This relatively long span can permit high frequency web fluctuations at the kiss transfer point, where the coating is applied to the web.
  • tensioning of the web can cause buckling in the crossweb direction, resulting in crossweb coating thickness deviations which manifest themselves in downweb marks.
  • FIG. 5 shows an offset gravure coater.
  • An intermediate offset roller 26 is used between the resilient backup roller 20 and the gravure roller 14.
  • the gravure and offset rollers may rotate in either direction, creating transfers in the forward or reverse mode.
  • this coater is used for very thin coatings.
  • the ratio between the web 18 and the gravure roller 14 speed can be as high as 10:1.
  • the offset roller 26 must be made of a resilient material so it can deform into the recesses of the gravure roller and pickout the fluid.
  • the effect of the variables at the transfer point between the gravure roller 14 and the offset roller 26 is similar to that of other gravure coaters.
  • the transfer to the web is made at a speed ratio close to 1:1 and the transfer from the offset roller 26 greatly attenuates the gravure roller recess pattern.
  • the invention is an apparatus and method of coating a fluid coating material on a substrate of material having a coating surface and an opposing, rear surface.
  • the coating surface of the substrate is contacted with a gravure roller which applies fluid coating material to the coating surface while the substrate is unsupported on the rear surface. After the coating material is applied, the rear surface of the substrate contacts an output roller less than 1.0 cm downstream of the gravure roller.
  • the output roller can be located above and spaced from the gravure roller to create a gap, causing the substrate to move between the gravure roller and the output roller at an upward angle.
  • the output roller can be located downstream from the gravure roller by a distance of less than 0.075 cm.
  • the gravure roller can be rotated in a direction opposite to the direction of the substrate to perform reverse gravure coating.
  • the rotation of the output roller can be driven independent of substrate contact, in the same direction as that of the substrate.
  • the substrate contacts the gravure roller by kissing the gravure roller and the substrate contacts the output roller by wrapping around the output roller.
  • the system can also include an idler roller around with the substrate passes upstream of the gravure roller.
  • the center of the idler roller can be located above the center of the gravure roller and below the center of the output roller.
  • tension isolation can be accomplished.
  • the tension at a portion of the substrate that contacts the gravure roller can be isolated from the tension at a portion of the substrate that is upstream of the gravure roller.
  • Higher or lower tension can be located upstream of the gravure roller.
  • Tension isolation can be accomplished by using a nip roller to nip the substrate to the output roller upstream of the gravure roller. This nipping can be performed upstream of the idler roller if one is used.
  • Figure l is a schematic view of a direct gravure coater.
  • Figure 2 is a schematic view of a differential speed gravure coater.
  • Figure 3 is a schematic view of a reverse gravure coater.
  • Figure 4 is a schematic view of a gravure kiss coater.
  • Figure 5 is a schematic view of an offset gravure coater.
  • Figure 6 is a schematic view of a reverse gravure kiss coater of the invention.
  • Figure 7 is a schematic view of another embodiment of the reverse gravure kiss coater of the invention.
  • the reverse gravure kiss coating system of the present invention coats a fluid coating material 10 on a substrate such as a web 18.
  • the web has a coating surface 28, on which the coating material 10 is coated, and an opposing rear surface 30. Any substrates that can be coated using kiss coating can be coated using this system.
  • One product for which this coating system works well is magnetic media, in which a wet coating of magnetizable particles in a binder is coated on a web.
  • the coating system includes rollers or other devices (not shown) for transporting the web to and from the coating station at which the web is coated. Referring to Figure 6, the web first passes an input idler roller 22 after which it travels to the gravure roller 14.
  • the idler roller 22 can be made rubber, carbon fiber composites, steel, aluminum or other materials.
  • the gravure roller 14 rotates in a direction opposite to the direction of web travel and deposits fluid coating material 10, stored in the knurls of the gravure pattern, onto the coating surface 28 of the web 18.
  • the coating material 10 can be deposited in the knurls in any manner, such as by rotating the gravure roller 14 through a pan 12 of coating material 10.
  • the gravure roller 14 contacts the web 18 in a free span without any support on the rear surface 30 of the web 18 opposite the line of contact between the gravure roller 14 and the web 18. As shown, the center of the idler roller 22 is above the center of the gravure roller 14.
  • a driven, large, accurate output roller 32 which can be a polished steel roller, is located downstream of the gravure roller 14.
  • the output roller 32 is driven in the same direction as the web 18, for example by a motor, independent of the web movement past it. As shown, the center of the idler roller 22 is below the center of the output roller 32.
  • the output roller 32 can have a diameter of about 12-16 cm, significantly larger than that of the idler roller 22. After the web 18 kisses the gravure roller 14 and is coated with the coating material 10, it wraps around the output roller 32, which serves as a take out roller.
  • the dynamic wetting line occurs in the short span between the gravure roller 14 and the output roller 32. This assures greater web stability during the transfer of the coating to the web, keeping the web motionless in the non-downweb directions. This eliminates web flutter and bag and prevents the wetting line from pulsing and causing caliper deviations known as chatter. This, in turn, yields superior downweb and crossweb uniformity when compared to conventional kiss coating using gravure rollers.
  • the output roller 32 can be located above the gravure roller 14.
  • the web 18 moves between the gravure roller 14 and the output roller 32 at an upward angle. Gravity has no effect and the entire system can be oriented with the web moving in any direction, even upside down.
  • the coating system has a reduced web span between the gravure roller 14 and the closest upstream idler roller 22 and a greatly reduced web span between the gravure roller 14 and the output roller 32, as compared to the common kiss coating systems. Because the kiss transfer point is less than 2.5 cm from the point of contact between the web 18 and the output roller 32, the amplitude of web fluctuations is small. Because the output roller 32 has stable supports and is accurately constructed, no web flutter is observed. This produces virtually uniform coating in the downweb direction. In the production of magnetic diskettes, this decreases diskette modulation and increases the performance of on-line image detection systems. Similarly, coating uniformity is important in other applications, such as those where optical clarity (whether measured objectively or subjectively using the human eye) is important.
  • the tension in the web upstream of the coating system can be isolated from the tension downstream of the coating system (the output web).
  • a nip roller 34 which can be upstream of the idler roller 22, nips the incoming web 18 between the output roller 32 and itself. This nipping allows a tension differential before and after the nipped contact with the output roller 32.
  • a higher tension can be located either upstream of the nip roller 34 or downstream of the nip roller 34.

Landscapes

  • Coating Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

A system of reverse gravure kiss coating of a fluid coating material (10) on a web (18) of material includes contacting a surface of the web with a gravure roller (14) while the web is unsupported on the rear surface (30). After the coating material is applied, the rear surface (30) is contacted with an output roller (32) downstream of the gravure roller (14). The output roller (32) can be driven and the web (18) wraps around the output roller (32). The tension at a portion of the web (18) that contacts the gravure roller (14) can be isolated from the tension at a portion of the web (18) that is upstream of the gravure roller (14) using a nip roller (34) to nip the web to the output roller (32) upstream of the gravure roller (14).

Description

REVERSE GRAVURE KISS COATING SYSTEM WITH OUTPUT ROLLER
TECHNICAL FIELD
The present invention relates to gravure coating. More particularly, the present invention relates to reverse gravure kiss coating with improved performance.
BACKGROUND OF THE INVENTION
Gravure coating, used for producing continuous coatings, uses a gravure roller with depressions or recesses on the surface which control the thickness and uniformity of the coated layer. Ideally the fluid is uniformly "picked out" of the recesses and transferred to the substrate. Typically these recesses are in a regular pattern in the region where a continuous coating is desired. Several styles of gravure coating may be used and designed to enhance individual recess or groove pickout, to transfer coating uniformly, and to optimize other coating responses such as roller surface life, scratching of the substrate, and pattern attenuation. Figure 1 shows a direct gravure coater. The coating fluid 10 is supplied from a pan 12 or other supply such as an extruder-type flow bar to the gravure roller 14. This coating fluid 10 is metered with a doctor blade 16 or roller, and is transferred to a substrate such as a web 18 at a nip point by contacting the web 18 with the fluid in the recesses using a resilient backup roller 20. The gravure roller 14 has etched, machined, or knurled recesses on its surface which can be any shape or size, discontinuous, or continuous over the roller surface.
The volume of these recesses controls the average coating thickness, and the specific geometry can be designed to enhance the stability of the pickout from the recesses. The ability to accurately control the volume and shape of these recesses together with the stability of the pickout of a consistent fraction of the fluid in these recesses improves coating thickness uniformity in the downweb and crossweb directions over other coating techniques. Typically the physical characteristics of interest are the average thickness, its uniformity, the presence of discontinuities (such as pinholes and streaks) , and the relative smoothness or initial leveling of the gravure roller pattern upon transfer to the web.
The removal of a fraction of the fluid from a recess is the pickout. There are three styles of stable pickout that can occur with transitions between them. Open coating is the transfer of fluid from the recesses individually with no fluid transferred in the region between them. Merged pickout occurs when the material in the recesses merges with the fluid in adjacent recesses to form a continuous coating at the time of transfer. Combined pickout is when the recesses combine together at the time of transfer to form a pattern that is a multiple or fraction of the recess pattern.
There are several controlling variables for pickout quantity and style in various gravure coating systems. The volume factor is the internal recess volume per unit area of the gravure roller surface. This controls the average wet coating thickness as a generally constant fraction of the available volume is picked out under similar operating conditions. A flooded inlet is an excess of fluid at the convergence of the web and gravure roller held there by their motion. Whenever a film split occurs in a diverging channel as at the roller exit on a forward roller coater, a natural liquid instability creates machine direction ribs in the coating. When imposing a gravure pattern other than the machine directional ribbing. enhanced individual groove pickout stability can be achieved by matching the frequency of the gravure pattern to the natural liquid ribbing instability frequency in the machine direction. The land/volume factor ratio influences the pickout style. A low land/volume factor ratio encourages merged pickout, and a high ratio promotes open coating. The helix angle is the angle that the grooves in a trihelical pattern make with the gravure roller shaft. Commercially available gravure roller patterns typically have a helix angle of 45°. Smaller helix angles promote pickout instability in forward gravure, and larger angles reduce the width of the pickout transition regions. The internal tooth angle is the angle between the opposing recess walls. Truncation is the flattening of the recess bottom.
Web thickness, web tensile modulus, backup roller hardness, and backup roller pressure all influence the average coating thickness because the effective volume factor of the gravure roller is reduced by any penetration of the web into the gravure roller recesses. Increased land widths improve gravure roller wear life. Decreasing land width and increasing the number of recesses enhances recess pattern attenuation at the transfer of the fluid to the web, promoting leveling of the fluid surface. The speed ratio is the ratio of the surface speed of the gravure roller to that of the web. The coating thickness may be changed by changing the speed ratio.
The design of the recess pattern for gravure coating influences the stability of the pickout of the fluid from the recesses. Seemingly minor changes in the discussed variables can change the maximum coating speed for stable pickout by hundreds of feet per minute and can affect the ability to achieve significantly thinner wet coatings.
As coating speeds are increased, stable, merged pickout becomes more difficult to achieve. An instability in the film split, at the web separation from the gravure roller, commonly referred to as misting (droplets of fluid spitting from the film split) generally occurs as coating speeds increase. One way to suppress misting is to reduce the gravure roller speed relative to the web and operate in a differential speed condition. The shear applied to the fluid as the film split occurs increases the operational coating speed before misting begins. Figure 2 shows a differential speed gravure coater. The web 18 is brought into a controlled engagement with the gravure roller 14 through relatively slight deformation of the backup roller 20 as compared to the high pressure no slip condition with direct gravure coating. The gravure roller 14 and resilient backup roller 20 are driven independently. There is a great deal of interaction between the variables in differential speed gravure coating. Successful operation at elevated speeds with merged pickout may be easily disturbed by minor changes in knurl design, coater head variables, or dispersion rheology. Changes in doctoring and speed ratio will alter the coating thickness. The changes may reverse as the result of interactions with other variables. Figure 3 shows a reverse gravure coater. The operation of this gravure coater is similar to that of a differential speed coater but the gravure roller surface moves in the opposite direction to the web. Again, the web 18 is brought into a controlled engagement with the gravure roller 14 through position control of the resilient backup roller 20. The gravure roller 14 and backup roller 20 are driven independently. The surface speed of the gravure roller 14 may be above or below web speed. Reverse gravure generally exhibits a larger operating window for acceptable coating than do other gravure coaters.
■A- Figure 4 shows a gravure kiss coater. As the gravure roller 14 may be rotated in either direction, fluid supply and doctoring are not displayed. The operation of this gravure coater is similar to that of a reverse gravure coater but the web 18 is brought into contact with the gravure roller 14 by positioning an input idler roller 22 and output idler roller 24 to create a slight wrap over the gravure roller 14. The surface speed of the gravure roller 14 may be above or below the speed of the web 18. With proper recess design and fluid rheology, fluids which do not totally attenuate the recess pattern upon transfer with other gravure styles may do so with this technique.
In reverse gravure kiss coating, the web 18 passes between the idler rollers 22, 24 in a free span. There is a relatively long span between the idler rollers 22, 24 adjacent the gravure roller 14. This span can be 30 cm, with the gravure roller 14 centered between the idler rollers 22, 24. This relatively long span can permit high frequency web fluctuations at the kiss transfer point, where the coating is applied to the web. Also, tensioning of the web can cause buckling in the crossweb direction, resulting in crossweb coating thickness deviations which manifest themselves in downweb marks.
Figure 5 shows an offset gravure coater. An intermediate offset roller 26 is used between the resilient backup roller 20 and the gravure roller 14. The gravure and offset rollers may rotate in either direction, creating transfers in the forward or reverse mode. Typically this coater is used for very thin coatings. The ratio between the web 18 and the gravure roller 14 speed can be as high as 10:1. The offset roller 26 must be made of a resilient material so it can deform into the recesses of the gravure roller and pickout the fluid. The effect of the variables at the transfer point between the gravure roller 14 and the offset roller 26 is similar to that of other gravure coaters. Generally the transfer to the web is made at a speed ratio close to 1:1 and the transfer from the offset roller 26 greatly attenuates the gravure roller recess pattern.
SUMMARY OF THE INVENTION
The invention is an apparatus and method of coating a fluid coating material on a substrate of material having a coating surface and an opposing, rear surface. The coating surface of the substrate is contacted with a gravure roller which applies fluid coating material to the coating surface while the substrate is unsupported on the rear surface. After the coating material is applied, the rear surface of the substrate contacts an output roller less than 1.0 cm downstream of the gravure roller.
The output roller can be located above and spaced from the gravure roller to create a gap, causing the substrate to move between the gravure roller and the output roller at an upward angle. The output roller can be located downstream from the gravure roller by a distance of less than 0.075 cm.
The gravure roller can be rotated in a direction opposite to the direction of the substrate to perform reverse gravure coating. The rotation of the output roller can be driven independent of substrate contact, in the same direction as that of the substrate. The substrate contacts the gravure roller by kissing the gravure roller and the substrate contacts the output roller by wrapping around the output roller.
The system can also include an idler roller around with the substrate passes upstream of the gravure roller. The center of the idler roller can be located above the center of the gravure roller and below the center of the output roller. In one modification, tension isolation can be accomplished. The tension at a portion of the substrate that contacts the gravure roller can be isolated from the tension at a portion of the substrate that is upstream of the gravure roller. Higher or lower tension can be located upstream of the gravure roller. Tension isolation can be accomplished by using a nip roller to nip the substrate to the output roller upstream of the gravure roller. This nipping can be performed upstream of the idler roller if one is used.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l is a schematic view of a direct gravure coater. Figure 2 is a schematic view of a differential speed gravure coater.
Figure 3 is a schematic view of a reverse gravure coater.
Figure 4 is a schematic view of a gravure kiss coater.
Figure 5 is a schematic view of an offset gravure coater.
Figure 6 is a schematic view of a reverse gravure kiss coater of the invention. Figure 7 is a schematic view of another embodiment of the reverse gravure kiss coater of the invention.
DETAILED DESCRIPTION
The reverse gravure kiss coating system of the present invention coats a fluid coating material 10 on a substrate such as a web 18. The web has a coating surface 28, on which the coating material 10 is coated, and an opposing rear surface 30. Any substrates that can be coated using kiss coating can be coated using this system. One product for which this coating system works well is magnetic media, in which a wet coating of magnetizable particles in a binder is coated on a web. The coating system includes rollers or other devices (not shown) for transporting the web to and from the coating station at which the web is coated. Referring to Figure 6, the web first passes an input idler roller 22 after which it travels to the gravure roller 14. The idler roller 22 can be made rubber, carbon fiber composites, steel, aluminum or other materials.
The gravure roller 14 rotates in a direction opposite to the direction of web travel and deposits fluid coating material 10, stored in the knurls of the gravure pattern, onto the coating surface 28 of the web 18. The coating material 10 can be deposited in the knurls in any manner, such as by rotating the gravure roller 14 through a pan 12 of coating material 10. The gravure roller 14 contacts the web 18 in a free span without any support on the rear surface 30 of the web 18 opposite the line of contact between the gravure roller 14 and the web 18. As shown, the center of the idler roller 22 is above the center of the gravure roller 14.
A driven, large, accurate output roller 32, which can be a polished steel roller, is located downstream of the gravure roller 14. The output roller 32 is driven in the same direction as the web 18, for example by a motor, independent of the web movement past it. As shown, the center of the idler roller 22 is below the center of the output roller 32. The output roller 32 can have a diameter of about 12-16 cm, significantly larger than that of the idler roller 22. After the web 18 kisses the gravure roller 14 and is coated with the coating material 10, it wraps around the output roller 32, which serves as a take out roller.
There is a short span between the kiss contact between the gravure roller 14 and the web 18 and the wrapping contact of the web 18 around the output roller 32. This distance can be less than 1 cm and in some cases can be less than 0.075 cm. The dynamic wetting line occurs in the short span between the gravure roller 14 and the output roller 32. This assures greater web stability during the transfer of the coating to the web, keeping the web motionless in the non-downweb directions. This eliminates web flutter and bag and prevents the wetting line from pulsing and causing caliper deviations known as chatter. This, in turn, yields superior downweb and crossweb uniformity when compared to conventional kiss coating using gravure rollers.
As shown, the output roller 32 can be located above the gravure roller 14. The web 18 moves between the gravure roller 14 and the output roller 32 at an upward angle. Gravity has no effect and the entire system can be oriented with the web moving in any direction, even upside down.
The coating system has a reduced web span between the gravure roller 14 and the closest upstream idler roller 22 and a greatly reduced web span between the gravure roller 14 and the output roller 32, as compared to the common kiss coating systems. Because the kiss transfer point is less than 2.5 cm from the point of contact between the web 18 and the output roller 32, the amplitude of web fluctuations is small. Because the output roller 32 has stable supports and is accurately constructed, no web flutter is observed. This produces virtually uniform coating in the downweb direction. In the production of magnetic diskettes, this decreases diskette modulation and increases the performance of on-line image detection systems. Similarly, coating uniformity is important in other applications, such as those where optical clarity (whether measured objectively or subjectively using the human eye) is important.
In the embodiment of Figure 7, the tension in the web upstream of the coating system (the input web) can be isolated from the tension downstream of the coating system (the output web). A nip roller 34, which can be upstream of the idler roller 22, nips the incoming web 18 between the output roller 32 and itself. This nipping allows a tension differential before and after the nipped contact with the output roller 32. A higher tension can be located either upstream of the nip roller 34 or downstream of the nip roller 34.

Claims

1. A method of coating a fluid coating material on a substrate 18 of material having a coating surface 28 and an opposing, rear surface 30, wherein the method comprises the steps of: contacting the coating surface 28 of the substrate with a gravure roller 14 having fluid coating material 10 to apply the fluid coating material to the coating surface of the substrate 18 in a free span while the substrate is unsupported on the rear surface 30; and contacting the rear surface 30 of the substrate 18 with an output roller 32 at a point on the substrate less than 1.0 cm downstream of the gravure roller 14.
2. The method of claim 1 further comprising: locating the output roller 32 above and spaced from the gravure roller 14 to create a gap; and moving the substrate 18 between the gravure roller 14 and the output roller 32 at an upward angle.
3. The method of any of claims 1 and 2 further comprising at least one of the steps of rotating the gravure roller 14 in a direction opposite to the direction of the substrate 18 to perform reverse gravure coating; and driving, independent of substrate 18 contact, the rotation of the output roller 32 in a direction that is the same as the direction of the substrate.
4. The method of any of claims 1, 2, and 3 further comprising the step of passing the substrate 18 around an idler roller 22 upstream of the gravure roller 14.
5. The method of any of claims 1, 2, 3, and 4 wherein the contacting the coating surface 28 step comprises kissing the coating surface of the substrate 18 with the gravure roller 14 and wherein the contacting the rear surface step 30 comprises wrapping the substrate around the output roller 32.
6. The method of any of claims 1, 2, 3, 4, and 5 further comprising the step of isolating tension between a portion of the substrate 18 that contacts the gravure roller 14 and a portion of the substrate that is upstream of the gravure roller.
7. The method of claim 6 further comprising the step of passing the substrate 18 around an idler roller 22 upstream of the gravure roller 14 and wherein the isolating tension step comprises nipping the substrate to the output roller 32 upstream of the idler roller and upstream of the gravure roller.
8. An apparatus for coating a fluid coating material 10 on a substrate 18 of material having a coating surface 28 and an opposing, rear surface 30, wherein the apparatus comprises: a gravure roller 14 which contacts the coating surface 28 of the substrate 18 with a fluid coating material 10 to apply the fluid coating material to the coating surface of the substrate in a free span while the substrate is unsupported on the rear surface 30; and means for contacting the rear surface 30 of the substrate 18 at a point on the substrate less than 1.0 cm downstream of the gravure roller 14 comprising an output roller 32.
9. The apparatus of claim 8 further comprising at least one of means for rotating the gravure roller
14 in a direction opposite to the direction of the substrate 18 to perform reverse gravure coating; and means for rotating, independent of substrate 18 contact, the output roller 32 in a direction that is the same as the direction of the substrate.
10. The apparatus of any of claims 8 and 9 further comprising an idler roller 22 around which the substrate 18 passes upstream of the gravure roller 14.
11. The apparatus of any of claims 8, 9, and 10 further comprising means for isolating tension between a portion of the substrate 18 that contacts the gravure roller 14 and a portion of the substrate that is upstream of the gravure roller.
12. The apparatus of claim 11 further comprising an idler roller 22 around which the substrate 18 passes upstream of the gravure roller 14 and wherein the isolating tension means comprises a nip roller 34 located upstream of the idler roller for nipping the substrate to the output roller.
13. The apparatus of any of claims 8, 9, 10, and 11 wherein the output roller 32 is a steel roller.
EP96924550A 1995-08-31 1996-07-17 Reverse gravure kiss coating system with output roller Expired - Lifetime EP0847308B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US52245995A 1995-08-31 1995-08-31
US522459 1995-08-31
PCT/US1996/011802 WO1997007899A1 (en) 1995-08-31 1996-07-17 Reverse gravure kiss coating system with output roller

Publications (2)

Publication Number Publication Date
EP0847308A1 true EP0847308A1 (en) 1998-06-17
EP0847308B1 EP0847308B1 (en) 2000-01-05

Family

ID=24080954

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96924550A Expired - Lifetime EP0847308B1 (en) 1995-08-31 1996-07-17 Reverse gravure kiss coating system with output roller

Country Status (7)

Country Link
EP (1) EP0847308B1 (en)
JP (1) JPH11511377A (en)
KR (1) KR19990043985A (en)
CN (1) CN1193928A (en)
CA (1) CA2228566A1 (en)
DE (1) DE69606049T2 (en)
WO (1) WO1997007899A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7625605B2 (en) 2004-12-30 2009-12-01 3M Innovative Properties Company Method for coating a surface with a pattern of coating fluid
US8739727B2 (en) 2004-03-09 2014-06-03 Boston Scientific Scimed, Inc. Coated medical device and method for manufacturing the same

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0986112A3 (en) * 1998-09-11 2004-02-04 Agilent Technologies, Inc. (a Delaware corporation) An efficient method for fabricating organic light emitting diodes
CN1101278C (en) * 1999-12-07 2003-02-12 富士机械工业株式会社 Coater for coating liquid onto sheet material
DE10315458B4 (en) * 2003-04-04 2010-11-04 Lohmann Gmbh & Co. Kg Process for the preparation of adhesive process or protective films, pressure-sensitive adhesive products obtainable thereby and their use for temporarily fixing and covering as well as for transporting workpieces
JP5191700B2 (en) * 2007-07-12 2013-05-08 富士フイルム株式会社 Bearing structure of coating roll, coating device, and coating method
FI20085765A0 (en) * 2008-08-11 2008-08-11 Upm Kymmene Corp Process for producing printing paper
WO2011030720A1 (en) * 2009-09-10 2011-03-17 日産自動車株式会社 Method for manufacturing fuel cell gas diffusion layer, fuel cell gas diffusion layer, and fuel cell
US9034437B1 (en) 2012-01-20 2015-05-19 Controlled Displacement Technologies, Llc Method and apparatus for a coating process for the deposition of a fluent coating onto a three-dimensional surface
CN102974497B (en) * 2012-11-01 2015-09-16 合肥乐凯科技产业有限公司 A kind of novel micro-gravure coating apparatus
CN103357536B (en) * 2013-06-28 2016-03-02 苏州市新广益电子有限公司 The coating machine of changeable coating method and coating process thereof
US10492550B2 (en) 2014-01-28 2019-12-03 Under Armour, Inc. Article of apparel including thermoregulatory textile
CN105728256A (en) * 2016-04-29 2016-07-06 玖龙纸业（太仓）有限公司 Production device and production method for coated duplex board with grey back
US11330851B2 (en) 2016-05-31 2022-05-17 Nike, Inc. Apparel thermo-regulatory system
KR102218546B1 (en) * 2017-12-26 2021-02-19 주식회사 엘지화학 Gravure coating apparatus
CN113707400B (en) * 2020-05-21 2023-04-25 青岛云路先进材料技术股份有限公司 Amorphous alloy strip with ultrathin coating and preparation method and equipment thereof

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1313630A (en) * 1959-03-25 1962-12-28 Champion Papers Inc Coated paper making machine
US3762365A (en) * 1972-02-24 1973-10-02 Polytype Ag Web coating apparatus
JPH027663Y2 (en) * 1985-09-06 1990-02-23
EP0408283B1 (en) * 1989-07-12 1995-09-27 Canon Kabushiki Kaisha Apparatus for producing substrate sheet for optical recording mediums and process for producing substrate sheet for optical recording mediums making use of it, apparatus for producing optical recording medium and process for producing optical recording medium making use of it.
DE4014463A1 (en) * 1990-05-07 1991-11-14 Jagenberg Ag DEVICE FOR COATING A MATERIAL SHEET, IN PARTICULAR A PAPER OR CARDBOARD SHEET
DE4218596C2 (en) * 1992-06-05 1996-05-02 Voith Gmbh J M Coating device for indirect application of coating color on a paper or cardboard web

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9707899A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8739727B2 (en) 2004-03-09 2014-06-03 Boston Scientific Scimed, Inc. Coated medical device and method for manufacturing the same
US7625605B2 (en) 2004-12-30 2009-12-01 3M Innovative Properties Company Method for coating a surface with a pattern of coating fluid

Also Published As

Publication number Publication date
KR19990043985A (en) 1999-06-25
WO1997007899A1 (en) 1997-03-06
CA2228566A1 (en) 1997-03-06
EP0847308B1 (en) 2000-01-05
DE69606049D1 (en) 2000-02-10
JPH11511377A (en) 1999-10-05
DE69606049T2 (en) 2000-08-03
CN1193928A (en) 1998-09-23

Similar Documents

Publication Publication Date Title
EP0847308B1 (en) Reverse gravure kiss coating system with output roller
US4948635A (en) Gravure coating device and method
US4299186A (en) Method and apparatus for applying a viscous fluid to a substrate
US4442144A (en) Method for forming a coating on a substrate
US3951102A (en) Roller coating apparatus
CA1285381C (en) Apparatus for coating moving strips of material
KR950013989B1 (en) Method and apparatus for coating
JPH03152300A (en) Device and method for covering short dowel
US3526536A (en) Process and apparatus for bead coating a web
US4712506A (en) Device for two-sided coating of a paper web
JP2578631B2 (en) Coating device for magnetic recording media
JPH0677709B2 (en) Transfer device
US4808445A (en) Coating apparatus and method
JP2001087695A (en) Coating device
JP2578183B2 (en) Coating equipment
JPS6242764A (en) Method for coating both faces of film or sheet
JP4217939B2 (en) Rod application method and apparatus
JPH06165963A (en) Coating applicator
JP2518440Y2 (en) Coating blade
JP2525839B2 (en) Coating equipment
JP3179628B2 (en) Hard substrate coating method
JPH04156969A (en) Coating device
KR930010195B1 (en) Coating device and coating method
JPH0724382A (en) Roll coater
JPH11605A (en) Coating method for continuously running film

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19980130

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT

17Q First examination report despatched

Effective date: 19981117

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT

REF Corresponds to:

Ref document number: 69606049

Country of ref document: DE

Date of ref document: 20000210

ET Fr: translation filed
ITF It: translation for a ep patent filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20000703

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20000706

Year of fee payment: 5

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010717

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20010717

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20020329

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050717

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20060731

Year of fee payment: 11

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080201