WO2007077295A1 - Method and apparatus for degassing coating color - Google Patents

Method and apparatus for degassing coating color Download PDF

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Publication number
WO2007077295A1
WO2007077295A1 PCT/FI2006/050540 FI2006050540W WO2007077295A1 WO 2007077295 A1 WO2007077295 A1 WO 2007077295A1 FI 2006050540 W FI2006050540 W FI 2006050540W WO 2007077295 A1 WO2007077295 A1 WO 2007077295A1
Authority
WO
WIPO (PCT)
Prior art keywords
coating color
degassing
degassing apparatus
coating
fed
Prior art date
Application number
PCT/FI2006/050540
Other languages
French (fr)
Inventor
Esa Forsten
Eero Kesti
Original Assignee
Metso Paper, Inc.
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 Metso Paper, Inc. filed Critical Metso Paper, Inc.
Priority to JP2008540644A priority Critical patent/JP2009516581A/en
Priority to EP06820119A priority patent/EP1965884A4/en
Publication of WO2007077295A1 publication Critical patent/WO2007077295A1/en

Links

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0021—Degasification of liquids by bringing the liquid in a thin layer
    • B01D19/0026—Degasification of liquids by bringing the liquid in a thin layer in rotating vessels or in vessels containing movable parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0036—Flash degasification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0042—Degasification of liquids modifying the liquid flow
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0073—Degasification of liquids by a method not covered by groups B01D19/0005 - B01D19/0042
    • B01D19/0078—Degasification of liquids by a method not covered by groups B01D19/0005 - B01D19/0042 by vibration
    • 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
    • D21H23/78—Controlling or regulating not limited to any particular process or apparatus

Definitions

  • the present invention relates to a method and apparatus for improving the degassing of coating color.
  • the mixing of gases, such as air, with the liquids and compositions used in a process typically causes several problems.
  • gas and gas bubbles in the coating color result in roughness on the surface of the paper in coating, and even areas where there is no coating at all.
  • This problem is greater with some coating colors than others, but the problem is emphasised particularly with those coating colors that accumulate more gas than others.
  • coating colors containing talc typically contain large amounts of gas due to the properties of talc.
  • the significance of the problem is further affected by the coating method used. For example, in curtain coating, the gas content of the coating may be at most 0-0,25% by volume. Otherwise the gas bound by the coating may result in uncoated areas in the material to be coated, such as paper or board.
  • various vacuum deaerators including an embodiment comprising a rotating drum arranged inside a vacuum container, into which drum the coating color is supplied, whereupon the coating color rises up the inner wall of the drum by the effect of centrifugal force and is discharged from the drum as a thin film colliding with the wall of the vacuum container.
  • the problem with prior art vacuum deaerators is their insufficient deaeration efficiency, especially with highly viscous substances. This is due to the fact that the small air bubbles contained in highly viscous coating colors are unable, even under an extremely high vacuum, that is, absolute pressure, to grow large enough to be broken or to be distinguished due to their specific rising rate.
  • the aim of the method and apparatus according to the present invention is to provide an improved degassing solution, by means of which the gas contained in coating color can be removed better than before.
  • the method relating to the invention is characterised in that in the method, oscillatory action is applied to the coating color flow to be fed into the degassing apparatus at a point before the degassing apparatus, which causes the gas bubbles to integrate or their size to increase in the coating color flow fed into the degassing apparatus.
  • the apparatus relating to the invention is, for its part, characterised in that the apparatus comprises means for producing oscillatory action in the coating color flow to be fed into the degassing apparatus to cause the gas bubbles to integrate and/or their size to increase in the coating color flow to be fed into the degassing apparatus, the said means being located in a position before the degassing apparatus in the coating color supply pipe.
  • the oscillation means are preferably located so that they are not in contact with the coating color, for example, located in a position on the outer surface of the supply pipe.
  • the apparatus comprises coating color supply means 2, for example a pump, which causes the coating color to flow from the storage container 1 to the degassing apparatus 4, which may be any known degassing apparatus.
  • the degassing apparatus is a vacuum-operated apparatus connected to a vacuum source 5.
  • the degassing apparatus 4 is preferably provided an absolute pressure of approximately
  • Reference numeral 6 indicates a discharge pump for the coating color flow from the degassing treatment, by means of which pump the coating color is supplied to the place of application, such as a curtain coater.
  • oscillatory action is applied to the coating color flow to be supplied to the degassing apparatus, for example, by means of an ultrasonic oscillator 3, which is located in conjunction with the pipe 7 leading from the pump 2 to the degassing apparatus 4, preferably on the outer surface of the pipe, so that the oscillator is not in direct contact with the coating color.
  • the oscillating frequency is preferably within the range from about 16 to about 60 kHz, which affects the gas bubbles in the coating color by making them bigger and thus easier to remove, for example, by means of a vacuum-operated degassing apparatus 4, or which break when they grow large enough. Due to the oscillation treatment, the efficiency of degassing increases considerably compared with using only a known degassing apparatus.
  • the oscillation treatment may also take place at frequencies markedly lower than the ultrasound frequency.
  • Coating color subjected to oscillation treatment may be at underpressure, overpressure or normal atmospheric pressure.
  • Overpressure is easily achieved, for example, by means of the supply pump 2 and underpressure, for example, by utilising the underpressure in the degassing apparatus 4.

Abstract

The invention relates to method and apparatus for improving the degassing of coating color. In the method, coating color is supplied from a coating color storage (1) by supply means (2) to the degassing apparatus (4), inside which are means for separating gas from the coating color. Oscillatory action is applied to the coating color flow to be fed into the degassing apparatus, which causes the gas bubbles to integrate and/or their size to increase in the coating color flow fed into the degassing apparatus.

Description

Method and apparatus for degassing coating color
The present invention relates to a method and apparatus for improving the degassing of coating color.
In the processing industry, the mixing of gases, such as air, with the liquids and compositions used in a process typically causes several problems. Especially when coating paper or a similar fibrous web material, gas and gas bubbles in the coating color result in roughness on the surface of the paper in coating, and even areas where there is no coating at all. This problem is greater with some coating colors than others, but the problem is emphasised particularly with those coating colors that accumulate more gas than others. For example, coating colors containing talc typically contain large amounts of gas due to the properties of talc. The significance of the problem is further affected by the coating method used. For example, in curtain coating, the gas content of the coating may be at most 0-0,25% by volume. Otherwise the gas bound by the coating may result in uncoated areas in the material to be coated, such as paper or board.
In multilayer curtain coating, the significance of degassing is even greater. Thus, if there are, for example, three or four coating layers, the coating used to produce each layer must be degassed as carefully as possible.
For removing the gas mixed with or dissolved in coating color have been developed, for example, various vacuum deaerators, including an embodiment comprising a rotating drum arranged inside a vacuum container, into which drum the coating color is supplied, whereupon the coating color rises up the inner wall of the drum by the effect of centrifugal force and is discharged from the drum as a thin film colliding with the wall of the vacuum container. The problem with prior art vacuum deaerators is their insufficient deaeration efficiency, especially with highly viscous substances. This is due to the fact that the small air bubbles contained in highly viscous coating colors are unable, even under an extremely high vacuum, that is, absolute pressure, to grow large enough to be broken or to be distinguished due to their specific rising rate. Attempts have been made to eliminate this problem by increasing the vacuum, but as a result of this, the solvent used in the coating color, for example water, vaporises extremely readily, whereupon the solids content of the coating color increases. Another method used is to increase processing times, but in that case the operational capacity of the deaerators will decrease, which means that a greater number of deaerators must be acquired or their size increased.
The aim of the method and apparatus according to the present invention is to provide an improved degassing solution, by means of which the gas contained in coating color can be removed better than before.
To achieve this aim, the method relating to the invention is characterised in that in the method, oscillatory action is applied to the coating color flow to be fed into the degassing apparatus at a point before the degassing apparatus, which causes the gas bubbles to integrate or their size to increase in the coating color flow fed into the degassing apparatus.
The apparatus relating to the invention is, for its part, characterised in that the apparatus comprises means for producing oscillatory action in the coating color flow to be fed into the degassing apparatus to cause the gas bubbles to integrate and/or their size to increase in the coating color flow to be fed into the degassing apparatus, the said means being located in a position before the degassing apparatus in the coating color supply pipe. The oscillation means are preferably located so that they are not in contact with the coating color, for example, located in a position on the outer surface of the supply pipe. The invention is described in greater detail in the following, with reference to the accompanying drawing, the only picture of which shows diagrammatically the apparatus for degassing coating color.
The apparatus comprises coating color supply means 2, for example a pump, which causes the coating color to flow from the storage container 1 to the degassing apparatus 4, which may be any known degassing apparatus. In the embodiment shown, the degassing apparatus is a vacuum-operated apparatus connected to a vacuum source 5. In the degassing apparatus 4 is preferably provided an absolute pressure of approximately
1 kPa - 15 kPa. If a lower absolute pressure is provided in the chamber, this will mean, among other things, that the evaporating point of the solvent contained in the coating color will fall and there will be a risk of the quality of the coating color changing as a result of degassing. On the other hand, if a higher absolute pressure is provided in the chamber, this will not necessarily suffice to increase the size of gas bubbles in the coating color and to remove them by means of a vacuum. An absolute pressure of about 3 kPa - 15 kPa in the vacuum container is highly preferable. By raising the lower limit of the absolute pressure used is ensured even better that the coating color will not be able to vaporise during degassing.
Reference numeral 6 indicates a discharge pump for the coating color flow from the degassing treatment, by means of which pump the coating color is supplied to the place of application, such as a curtain coater.
According to the invention, oscillatory action is applied to the coating color flow to be supplied to the degassing apparatus, for example, by means of an ultrasonic oscillator 3, which is located in conjunction with the pipe 7 leading from the pump 2 to the degassing apparatus 4, preferably on the outer surface of the pipe, so that the oscillator is not in direct contact with the coating color. The oscillating frequency is preferably within the range from about 16 to about 60 kHz, which affects the gas bubbles in the coating color by making them bigger and thus easier to remove, for example, by means of a vacuum-operated degassing apparatus 4, or which break when they grow large enough. Due to the oscillation treatment, the efficiency of degassing increases considerably compared with using only a known degassing apparatus. The oscillation treatment may also take place at frequencies markedly lower than the ultrasound frequency.
Coating color subjected to oscillation treatment may be at underpressure, overpressure or normal atmospheric pressure. Overpressure is easily achieved, for example, by means of the supply pump 2 and underpressure, for example, by utilising the underpressure in the degassing apparatus 4.

Claims

Claims
1. A method for improving the degassing of coating color, in which method the coating color is supplied from a coating color storage (1) by supply means (2) to the degassing apparatus (4), inside which are means for separating gas from the coating color, characterised in that in the method, oscillatory action is applied to the coating color flow to be fed into the degassing apparatus at a point before the degassing apparatus, which causes the gas bubbles to integrate and/or their size to increase in the coating color flow fed into the degassing apparatus.
2. A method as claimed in claim 1, characterised in that in the method, oscillatory action is applied to the coating color flow at ultrasonic frequency.
3. A method as claimed in claim 2, characterised in that in the method is used an ultrasonic frequency ranging from 20 to 60 kHz.
4. A method as claimed in any of the claims 1 to 3, characterised in that the oscillatory treatment is carried out on coating color at underpressure, overpressure or normal atmospheric pressure.
5. An apparatus for removing gas contained in coating color, the said apparatus comprising means (2) for supplying coating color from a coating color storage (1) to the degassing apparatus (4), inside which are means for separating gas from the coating color, characterised in that the apparatus comprises means (3) for producing oscillatory action in the coating color flow to be fed into the degassing apparatus (4) to cause the gas bubbles to integrate and/or their size to increase in the coating color flow to be fed into the degassing apparatus, the said means (3) being located in a position before the degassing apparatus in the coating color supply pipe (7). 6, An apparatus as claimed in claim 5, characterised in that the means (3) producing the oscillation produce oscillatory action at ultrasonic frequency.
PCT/FI2006/050540 2005-12-30 2006-12-05 Method and apparatus for degassing coating color WO2007077295A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2008540644A JP2009516581A (en) 2005-12-30 2006-12-05 Method and apparatus for degassing color paint
EP06820119A EP1965884A4 (en) 2005-12-30 2006-12-05 Method and apparatus for degassing coating color

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20055713A FI20055713L (en) 2005-12-30 2005-12-30 Method and apparatus for removing gas from a coating material
FI20055713 2005-12-30

Publications (1)

Publication Number Publication Date
WO2007077295A1 true WO2007077295A1 (en) 2007-07-12

Family

ID=35510791

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2006/050540 WO2007077295A1 (en) 2005-12-30 2006-12-05 Method and apparatus for degassing coating color

Country Status (5)

Country Link
EP (1) EP1965884A4 (en)
JP (1) JP2009516581A (en)
CN (1) CN101282774A (en)
FI (1) FI20055713L (en)
WO (1) WO2007077295A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009033938A1 (en) * 2007-09-07 2009-03-19 Voith Patent Gmbh Device and method for degassing a liquid or pasty medium
EP1976645B1 (en) * 2006-01-26 2011-03-23 Metso Paper, Inc. Method for processing and supplying a coating colour used for coating a fibrous web to a coating device
DE102009031106B4 (en) 2009-06-29 2022-02-17 Khs Gmbh Process and device for degassing a liquid

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101865187A (en) * 2010-05-18 2010-10-20 浙江大学 Ultrasonic on-line air removing device for hydraulic system
TWI644023B (en) * 2017-09-05 2018-12-11 Scientech Corporation Liquid delivery device

Citations (2)

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Publication number Priority date Publication date Assignee Title
JPH09164353A (en) * 1995-12-18 1997-06-24 Nkk Corp Roll coater coating device
US20030230193A1 (en) * 2002-06-18 2003-12-18 Louks John W. Electrostatic deaeration method

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US2147677A (en) * 1936-01-22 1939-02-21 Submarine Signal Co Method of deaerating liquids
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US4070167A (en) * 1976-03-08 1978-01-24 Eastman Kodak Company Sonic apparatus for removing gas from photographic emulsion
JPS59156405A (en) * 1983-02-28 1984-09-05 Konishiroku Photo Ind Co Ltd Ultrasonic defoaming method and apparatus therefor
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JPH09164353A (en) * 1995-12-18 1997-06-24 Nkk Corp Roll coater coating device
US20030230193A1 (en) * 2002-06-18 2003-12-18 Louks John W. Electrostatic deaeration method

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1976645B1 (en) * 2006-01-26 2011-03-23 Metso Paper, Inc. Method for processing and supplying a coating colour used for coating a fibrous web to a coating device
WO2009033938A1 (en) * 2007-09-07 2009-03-19 Voith Patent Gmbh Device and method for degassing a liquid or pasty medium
DE102009031106B4 (en) 2009-06-29 2022-02-17 Khs Gmbh Process and device for degassing a liquid

Also Published As

Publication number Publication date
CN101282774A (en) 2008-10-08
FI20055713A0 (en) 2005-12-30
EP1965884A1 (en) 2008-09-10
EP1965884A4 (en) 2011-04-27
FI20055713L (en) 2007-07-01
JP2009516581A (en) 2009-04-23

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