Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/02—Spray pistols; Apparatus for discharge
  • B05B7/06—Spray pistols; Apparatus for discharge with at least one outlet orifice surrounding another approximately in the same plane
  • B05B7/062—Spray pistols; Apparatus for discharge with at least one outlet orifice surrounding another approximately in the same plane with only one liquid outlet and at least one gas outlet
  • B05B7/066—Spray pistols; Apparatus for discharge with at least one outlet orifice surrounding another approximately in the same plane with only one liquid outlet and at least one gas outlet with an inner liquid outlet surrounded by at least one annular gas outlet
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
  • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
  • B05B5/03—Discharge apparatus, e.g. electrostatic spray guns characterised by the use of gas, e.g. electrostatically assisted pneumatic spraying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/02—Spray pistols; Apparatus for discharge
  • B05B7/025—Nozzles having elongated outlets, e.g. slots, for the material to be sprayed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/02—Spray pistols; Apparatus for discharge
  • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
  • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
  • B05B7/0861—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets with one single jet constituted by a liquid or a mixture containing a liquid and several gas jets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/02—Spray pistols; Apparatus for discharge
  • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
  • B05B7/0884—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point the outlet orifices for jets constituted by a liquid or a mixture containing a liquid being aligned
• • 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
  • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
  • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
  • B05C11/04—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with blades
• • 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
  • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
  • B05C11/02—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface
  • B05C11/06—Apparatus for spreading or distributing liquids or other fluent materials already applied to a surface ; Controlling means therefor; Control of the thickness of a coating by spreading or distributing liquids or other fluent materials already applied to the coated surface with a blast of gas or vapour
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/50—Spraying or projecting
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
  • D21H25/10—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with blades
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
  • D21H25/12—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with an essentially cylindrical body, e.g. roll or rod

Definitions

• paper, paper board, or other materi ⁇ als of this kind can be applied by various substances to change the surface texture, colour or the like.
• These coa ⁇ tings often contain clay (kaolin) or other relatively heavy materials as talc or chalk and binders as latex or modified starch, for filling up the somewhat porous surface of the paper or paper board to produce a smooth surface.
• the coatings improve the quality of the paper, e.g. the shine, the brightness, the transparency, the smoothness, the surface strength, the absorption characteristics.
• One or more coating layers are applied onto the surface of the uncoated paper to fill up roughness of the paper surface and thus to render the said surface even, to give a more smooth and microporous surface.
• the paper web is applied with different amounts of coating in one or more steps.
• An appropriate surplus of wet coating is applied onto the paper web using a dosing device, through which the paper is conveyed.
• a doctor or a so called doctor blade or knife which extends over the whole width of the paper web, is installed spaced from the dosing device. Until 90 % of the coating is scraped off. This wears down the blade and the maintenance, e.g. the changing of the doctor, is considerably time con ⁇ suming.
• a pro- cess and apparatus for coating a web is disclosed without mechanical contact, in which process the web is conveyed continuously along a path, the coating material is formed on the web in a slurry containing a solid particulate coa ⁇ ting, the slurry is broken up into small particles for pro- ducing a fog of coating material to be applied onto the web, said fog having solid particulate material as a gas suspension, a sufficient gas stream is produced to maintain the solid material in particle form in suspension, and the fog containing the solid particulate material is directed towards the web for adherence the solid particulate mate ⁇ rial onto the web.
• higher paper web speeds have been desired for to increase production rates.
• paper web speeds between 1000-1500 m/min are common and in the future even greater speeds will be possible.
• the present invention shows the characteristics disclosed in the cha ⁇ racterizing part of claim 1.
• the objective of this invention is generally coating or sizing paper webs or like and concerns especially a process and an apparatus for coating a web. Another objective of the invention is to obtain a smooth paper surface. Yet another objective is to obtain a better paper quality, so that the paper can be coated with a greater amount of coa ⁇ ting and/or the formerly attained coating amounts can be obtained using fewer coating steps.
• the pressure of the mechanical doctor can be decreased.
• the doctor blade pres ⁇ sure needed is considerably smaller than in existing devi- ces in industry.
• the wetting of the paper web can be dec ⁇ reased.
• the productional efficiency of the surface sizing is increased.
• This invention comprises making a slurry to be used as the coating material mixture or sizing mixture and producing a fog.
• the coating material mixture or sizing mixture before adherence it onto the paper, is broken up into a fog using a gas under pressure.
• the coated or surface sized web is treated by a doctor or it is pressed between two rotating rolls or like, to smooth the coating or sizing layer and to making possible the chemicals, the coating and/or the sizing to penetrate into the paper.
• the fog can be mixed with such fogs that contain other coatings if desired; then the final coatings are directed towards the web.
• the fog and the web can contain static charges, which help the fog to adhere and to stay on the web, even if, the pro ⁇ cess is successful even without using static charges.
• the fog can be generated in many different ways e.g. by using normal spray nozzles. In the invention ultra sonic energy and ultra sonic nozzles well known in the field can be employed.
• Figure 1 presents a cross sectional view of a schematic drawing of a coating nozzle.
• Figure 2 presents a schematic flow diagram showing the do ⁇ sing device of the invention for coating paper.
• Figure 3 presents different alternatives for smoothing the paper web, which has been coated using a paper machine or a separate coating machine.
• Figures 4 and 5 present structures of nozzles.
• an example of an application nozzle 24 is giv- en, where air channels 25 are disposed around the capillary tube 26 of the slurry channel.
• the coating slurry is brought in the form of a slurry to the slurry channel 26.
• the slurry channel and the air channels narrow off towards the outlet.
• the air from the air channels is directed to break up the slurry into a fog and to further break up it, if the slurry already has been reduced into a fog in an earlier stage.
• the coating mixture hits the paper web and adheres to it.
• the distance of the application nozzle from the paper can be adjusted according to the need.
• the slurry is conducted to the slurry channel in form of a slurry if it is dilute wherein it is broken up just a moment before it hits the paper.
• the outlet end of the nozzle has e.g. a diameter of 1-5 mm or 3-5 mm.
• the nozzles can be aligned in a row, over the width of the web to be coated, either in the same or a different plane, and the air and slurry chan ⁇ nels are arranged concentrically so that the fog broken up through them is applied evenly on the surface of the paper.
• the nozzle according to Figure 1 can be formed into one uniform nozzle where the outlet of the slurry channel is formed into a slot extending over the whole width of the web and its dimensions e.g.
• the amount of the coating applied can be easi ⁇ ly adjusted.
• the penetration of and the adhered coating can be optimized by defining for each spray a suitable hit angle of the spray.
• the optimal value of the angle is not critical in all circumstances as the excess coating can always be collected or scraped off, but then the paper strain is added.
• a suitable pressure for the breaking up/- accelerating gas ; (air) is 0,5-25 bar.
• a great pressure usu ⁇ ally leads to a greater coating mixture velocity after the nozzle and this results that the coating penetrates deeper in the paper pores.
• the deepest penetration in the paper is obtained when the nozzles are slightly inclined against the direction of the incoming paper web.
• the optimal angle of the nozzles against the paper web line depends, as was sta- ted, on:
• the pressure can be adjusted as nee ⁇ ded to obtain an acceptable coating.
• the apparatus is natu ⁇ rally provided with an appropriate air-conditioning system, which is not disclosed here.
• the web After application the web is conveyed through the doctor 32.
• the doctor blade is pressed against the roll 33.
• the knife pressure can be consi ⁇ derably lower than in coventional application techniques, as the amounts of the fed coating can be easily dosed, wherein an excess amount of coating can be avoided.
• the main function of the doctor can be to meter or level. In a pilot-plant test a coating amount of 25 g/m 2 was obtained in one coating step, whereas in conventional processes a coat- ing amount of 15-16 g/m 2 in one step was obtained on one side.
• a mechanical (or air) knife can function as brushing or removing slurry paste.
• the choice of the main function, between brushing or removing the paste, depends on the speed of the web to be coated, the type of paste and on the desired amounts of coating. A high blade pressure leads to a scraping phenomena and to an unwanted straining of the paper in removing the paste from the paper web. It is to be noted, that when paper is sized with a starch solution, the characteristics of this solution are totally different from the usual mineral coating or slurry.
• the surface si- zing and application speeds can be increased and it is es ⁇ timated that the velocity of 2000 m/min can be reached, which was the maximum speed of the test machine in one of the pilot-plant tests.
• the limit speed of the application can be said to be dependant on the mechanically reachable speed of the machine as on the ap ⁇ plication process itself.
• the application can be performed in one or more steps.
• the coated paper can be smoothened, doctored, instead of using a doctor or in combination with a doctor e.g. by passing it between two rolls. An air knife or air brush or any combination of these can also be employed.
• the slurry is remo ⁇ ved from the tank 10 by a pump 14, the outlet of which is connected to a line 15 for feeding a nozzle 16.
• the nozzle 16 breaks up the slurry from the tank 10 so that the slurry becomes a spray having a very small particle size or a fog size.
• the material will be referred to as a fog and it should be understood that this term in ⁇ cludes range of forms from a very small particle aerosol to a relatively small particle spray.
• the nozzle 16 may comprise many specific pieces of hardwa ⁇ re. It is possible, that by using the pump 14 having suffi ⁇ cient pressure, the nozzle 16 may actually be a fluid type nozzle, wherein the nozzle will break up the fluid that flows therethrough to produce a fine particle spray, or a nozzle, where a gas under pressure breaks up the liquid and mixes therewith to form a fog. It is also possible to use an ultrasonic nozzle, usually of the type disclosed in the US patent 4352459 of Berger et al. The ultrasonic nozzles are well known in the art, and those skilled in the art will understand without further explanation.
• the nozzle 16 may take, is a transducer located at the bottom of the tank 18. It will be noted, that the tank 18 is described as having some slurry in the bottom of it, and the fog in the upper part of the tank 18. By placing the transducer at the bottom of the tank 18, ultra sonic energy can break up the slurry into fine particles to produce the desired fog above the liquid, and the additional fog being generated is removed for use.
• the fog from the tank 18 is directed to a mixing chamber 19, and further that there is a second tank 18A, which also has its output directed to the mixing chamber 19.
• a second tank 18A which also has its output directed to the mixing chamber 19.
• Another means for providing two different materials for coating the web 11 is to provide two or more of the tanks as the tank 10.
• a second tank 10A is disclo ⁇ sed, and a pump 14A moves material from the tank 10A and feeds it through the line 15A to a nozzle 16A in the tank 18.
• a pump 14A moves material from the tank 10A and feeds it through the line 15A to a nozzle 16A in the tank 18.
• the mixed fogs will then be either directed to a mixing tank 19 or directly to the application nozzle 24.
• This invention provides also an injection device 23, which injects air or other gas to the stream of fog.
• the injecti- on means 23 are placed adjacent to the walls of the appli ⁇ cation nozzle 24 and in this position a curtain of gas is placed along the walls, to prevent the attachment of the droplets on the walls.
• a static electric charge will be utilized on the fog and on the web 11.
• the web 11 can be charged, and that the fog can be charged by means of grating or the like.
• a charge generator is indicated at 30, there being only one charge generator shown. Nevertheless, it will be understood, that one charge (e.g. a negative) can be generated on the substrate 11, while the opposite charge (e.g. a positive) can be placed on the fog. These opposite charges will cause the fog to be attracted to the substrate 11 and stick thereto.
• Figure 3a discloses an embodiment of a doctor 32, an air brush or their combinati- on.
• Figure 3b discloses a pair of rollers 34, used for a surface sized paper web, through which rollers the paper web is conducted.
• An air knife presented by a broken line can be added after the roller pair, if desired.
• the paper web can move upwards or in a horizontal direction.
• a small amount of pigment can be added to the starch, and this is called pigmentation.
• An important feature of this invention is the application of the fog containing coating material to a web 11 at low pressure and without mechanical manipulation or the like.
• This allows the system of the invention to be utilized for coating paper anywhere along the paper production line, from the first de-watering stage until the paper has been completely dried. If desired, the paper can be manufactured and rolled up, and the rolls can be transported to another location, unrolled and then coated using the system accor ⁇ ding to the invention. It will therefore be seen that this invention provides an extremely simple method and apparatus for coating a paper web or like. Since the slurry to be coated on the web is transformed into a fog and the fog is applied at very low pressure, it will be understood, that the web will never be harmed, even when the web contains much water. Furthermore, it will be understood that any conventional drying techni ⁇ que is appropriate so that infrared lamps or the like can be utilized to dry the coating on paper or board.
• the extra coating material that is accumulated to the doc ⁇ tor blade can be collected by usual means for later ex ⁇ ploitation.

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• Paper (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26159350

Family Applications (1)

Country Status (7)

Cited By (28)

Families Citing this family (2)

Citations (4)

• 1993
  • 1993-11-05 CA CA002148505A patent/CA2148505C/en not_active Expired - Fee Related
  • 1993-11-05 EP EP93924618A patent/EP0682571B1/en not_active Expired - Lifetime
  • 1993-11-05 FI FI934890A patent/FI96894C/fi not_active IP Right Cessation
  • 1993-11-05 WO PCT/FI1993/000453 patent/WO1994011116A1/en active IP Right Grant
  • 1993-11-05 BR BR9307399-2A patent/BR9307399A/pt not_active IP Right Cessation
  • 1993-11-05 AU AU54217/94A patent/AU5421794A/en not_active Abandoned
  • 1993-11-05 DE DE69323438T patent/DE69323438T2/de not_active Expired - Lifetime

Patent Citations (4)

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