EP0447420A1 - Procede et moyen d'enduction d'une bande de papier en au moins deux etapes - Google Patents

Procede et moyen d'enduction d'une bande de papier en au moins deux etapes

Info

Publication number
EP0447420A1
EP0447420A1 EP19890913225 EP89913225A EP0447420A1 EP 0447420 A1 EP0447420 A1 EP 0447420A1 EP 19890913225 EP19890913225 EP 19890913225 EP 89913225 A EP89913225 A EP 89913225A EP 0447420 A1 EP0447420 A1 EP 0447420A1
Authority
EP
European Patent Office
Prior art keywords
coating
paper
applicator
web
steps
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.)
Withdrawn
Application number
EP19890913225
Other languages
German (de)
English (en)
Inventor
Markku Niemi
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.)
KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
Original Assignee
KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
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 KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB filed Critical KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
Publication of EP0447420A1 publication Critical patent/EP0447420A1/fr
Withdrawn legal-status Critical Current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
    • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
    • B05C9/06—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying two different liquids or other fluent materials, or the same liquid or other fluent material twice, to the same side of the work
    • 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
    • D21H23/70—Multistep processes; Apparatus for adding one or several substances in portions or in various ways to the paper, not covered by another single group of this main group
    • D21H23/72—Plural serial stages only

Definitions

  • the present invention concerns a procedure for coating a paper web with an aqueous dispersion in at least two steps, employing in both steps a blade coat ⁇ ing method, in both steps coating material in excess being deposited on the surface of the paper, the coat ⁇ ing weight being controlled and the surplus being re- moved by scraping (with a blade) .
  • the invention further concerns a means for coating a paper web in at least two steps, said means comprising a first coating means which has been provid ⁇ ed with an applicator and a doctor blade and arranged to apply aqueous dispersion on the paper, to adjust the coating weight and to remove the surplus coating mate ⁇ rial by scraping with the doctor blade against a moving base in the first coating step, and a second coating means which has been provided with an applicator and a doctor blade and arranged to apply aqueous dispersion on the paper, to adjust the coating weight and to remove the surplus coating material by scraping with the doctor blade against a moving base in the second coating step.
  • Multiple-step coating without intermediate drying has previously been used in producing functional special coatings.
  • the coating material is most often a solution or a polymer melt, sometimes also a dispersion (e.g. DE .3 235 151, GB 1.159,208, GB 1,159,598, GB 1,207,133 and US 4,537,801).
  • the purpose with the coat- ing is to influence, for instance, the permeability to gases and aroma, release properties, photosensitivity, etc. It is important in all these instances that the coating forms a layer of uniform thickness, totally covering the surface. For this reason apparatus of the nozzle type is frequently employed to do the coating, with the aid of which on the surface of the paper is deposited a pre-adjusted quantity of the coating mate- rial, in a layer of uniform thickness.
  • the invention concerns the coating of paper or cardboard intended for use as a printing substrate, by a blade, or doctor, coating method, the principal ob- ject being to smooth out the unevenness of the surface.
  • Strict requirements are imposed on printing paper, that is, paper to be used as a printing sub ⁇ strate.
  • the purpose with the coating is to level out all unevenness of the surface. This implies that the thickness of the coating is variable.
  • the coating is accomplished in that on the surface of the paper is deposited a great excess of coating material and the major part thereof is scraped off. Coating material will then mainly remain in the depressions of the base paper, and the roughness of the paper will decrease.
  • Another problem is associated with the use of small coating material quantities.
  • the coating colour is applied on the surface of the precoating, water is most rapidly absorbed therefrom into the base. As a result, its dry matter content may increase to such extent that serious difficulties are encountered in the scraping process, such as streak formation for instance.
  • the object of the invention is to eliminate the problems mentioned.
  • the invention is based on the fundamental idea that the second coating step is implemented immediately after the first coating step so that the surface of the coating spread on the paper, and smoothed out by scrap ⁇ ing, in the first step is wet when the second step coating is applied, that is, the coating has not time to settle before implementation of the second step.
  • This is understood to mean that the second coating step is implemented before the surface of the first step coating has time to dry, i.e., before the water has time to be drained from the surface of the coating, prior to the second coating step.
  • the coating applied on the surface of the paper in the first step is thus wet, and the second coating step takes place in that the coating is applied upon the wet coating.
  • the second coating step is imple- mented, as to location, substantially in conjunction with the first step, i.e., as seen in the direction in which the web travels, immediately after the first step.
  • the first coating step may be implemented using any blade coating method, which implies that application of the coating colour, that is of the dis- persion, may be accomplished using e.g. roll applica ⁇ tion, nozzle or spraying application.
  • the main part, e-g- more than 50%, of the coating applied on the surface of the paper is-removed by scraping.
  • the procedure of the invention may be employed to coat paper on one and/or both sides. In that case either side of the paper may be coated in the manner just described in two or several steps.
  • the coating of paper is carried out substantial ⁇ ly in a single run coating operation, that is, using two consecutive doctor blades substantially in one uni- tary coating apparatus.
  • the first doctor spreads out the coating colour that has been applied on the surface of the paper and eliminates part of the surface rough ⁇ ness, said coating colour being advantageously an inex ⁇ pensive coating colour, with conventional coat weight or e.g. at 2-10 g/m 2 , advantageously 3-8 g/m 2 , depending on the roughness of the base web.
  • one may in the surface of the paper apply the coating, if desired, in a very thin layer, for instance 0.1-12 g/m 2 , advantageously 0.5-10 g/m* 2 .
  • the coating of paper can be carried out as an economical, tailor-made job, considering the customer's special requirements.
  • the properties of the paper can be regulated within wider limits than before.
  • coating material of high-standard qual ⁇ ity e.g. gloss-enhancing plastic pigments, precipitat ⁇ ed pigments improving the printer's ink absorption and the gloss, and optical brighteners boosting the brightness, and titanium dioxide, all of them with good economy.
  • the procedure may also be used for surface sizing with which thin pigmentation is combined. Thanks to the small amount, if such is desired, of the coating applied in the second step.
  • paper is under ⁇ stood to mean cellulose or mechanical pulp paper and/or cardboard types manufactured on a paper or cardboard machine.
  • Fig. 1 presents the implementation of the procedure of the invention when a certain means according to the invention is being used
  • Fig. 2 presents the implementation of a procedure ac ⁇ cording to another embodiment of the invention when an ⁇ other means according to the invention is being used
  • Fig. 3 presents the implementation of a procedure ac ⁇ cording to a third embodiment of the invention when a third means according to the invention is being used
  • Fig. 1 presents the implementation of the procedure of the invention when a certain means according to the invention is being used
  • Fig. 2 presents the implementation of a procedure ac ⁇ cording to another embodiment of the invention when an ⁇ other means according to the invention is being used
  • Fig. 3 presents the implementation of a procedure ac ⁇ cording to a third embodiment of the invention when a third means according to the invention is being used
  • Fig. 4 presents a fourth embodiment of the invention.
  • a means according to the invention for coating the paper web l in two steps.
  • the means comprises a first coating means 2; in the figure the coating means has been schematically depict ⁇ ed, in order to illustrate its principle design and function.
  • the coating means 2 comprises a conventional applicator roll 7, a coating material feeding means 8, and a doctor blade 3.
  • the applicator roll has been dis ⁇ posed to spread coating material on the paper web moving in the direction of the arrow d , against a moving base, such as a backing roll 4, and the doctor blade 3 levels the coating.
  • the means further comprises a second coating means 5, comprising a spray applicator 9 and, likewise, provided with a doctor blade 6 and arranged to apply coating material on the paper and to level the coating.
  • the second coating means 5 has been placed, in the direction of travel d of the web 1, immediately after the first coating means 2 so that the second coating step is implemented immediately after the first coating step, so that the surface of the coating spread and scraped in the first step is wet, that is, the coating has not time to settle before the second step.
  • the applicators 7,9 and doctor blades 3,6 have been disposed against one and the same backing roll 4.
  • the first coating means 2 and the sec ⁇ ond coating means 5 constitute a functional entity, that is one single unit in which the coating of the paper takes place in two steps, the latter step follow ⁇ ing immediately after the preceding step.
  • the second coating means 5 is based on the spray application mode known in itself in the art, this means comprising a coating material spray applicator 9 for applying coating material on the sur ⁇ face of the paper, and a doctor blade 6.
  • the applicator may be any kind of device known in the art.
  • the quan ⁇ tity of the coating material that remains on the sur ⁇ face of the web is regulated by controlling the pres ⁇ sure of the doctor blade 6 against the web.
  • the blade 6 may be positioned e.g. at an oblique angle against the web, e.g. 3-80°, such as 5-60°, sloping in the direc ⁇ tion of travel of the web.
  • the feed 20 of coating colour to the lifting roll applicator 7, and similarly the feed 21 of coating paste to the spray applicator (as well as the design of the applicators, and the design of the respective doctor blades 3,6) is in itself known in the art, and no closer description of them is given in this context.
  • the way in which the surplus pastes 23,24 are returned to the feed of the applicator is likewise known in the art and will not be more closely described.
  • nozzle or spray application is used in the first coating step, that is in the applicator 2
  • lifting roll application in the second coating step that is in the applicator 5
  • nozzle or spray application is used in the second coating step.
  • Other alternatives are: lifting roll application in the first step and lifting roll application in the second; nozzle or spray application in the first step and noz ⁇ zle or spray application in the second; and nozzle or spray application in the first step and lifting roll application in the second step.
  • Fig. 2 is seen an embodiment of the means of the invention which comprises a first coating means 2 and a second coating means 5.
  • the first coating means 2 comprises a nozzle applicator 10 and therewith con ⁇ nected a doctor blade 3 (so-called SDTA apparatus) , disposed to apply the coating paste on the web 1.
  • the doctor blade has been arranged to scrape and level the coating, the surplus 23 (more than half, possibly more than 80%) to be conducted back to the coating material circulation.
  • the second coating means 5 has been placed immediately after the first coating means, in the direction of travel of the web.
  • the second coating means comprises a spray applicator 11 with feed 21, and a doctor blade 6 with return 24 to the feed 21.
  • the coating means 5 has been arranged to feed the coating of the second step onto the web 1 after the doctor blade 3 of the first coating means 2. Coating of the web takes place on a relative short distance, i.e., the coating means have been placed immediately adjacent to each other, e.g. on a distance of 1-15 cm, such as 1-10 cm, possibly 1-5 cm.
  • Fig. 3 is depicted an embodiment comprising a first coating means 2, a second coating means 5 and a third coating means 12, with doctor blades 3, 6 and 13, respectively, disposed in this order in the direction of travel of the web 1 , immediately one after the other.
  • the respective applicators are seen in the fig ⁇ ure: a lifting roll applicator 7, spray applicators 13 and 14, respectively, with feeds 29, 21 and 22, respec ⁇ tively.
  • the coating means 2 corresponds to the first step applicator 2 in Fig. 1, and the appli ⁇ a- tors 5 and 12 correspond mainly to the coating means 5 in Fig. 2.
  • the coating rate can be regulated in each step by controlling the pressure of the respective blades against the web.
  • the surplus coating materials 23, 24 and 25 are returned to the respective feeds of the applicators.
  • the coating means 2, 5 and 12 then constitute a unitary entity for coating the web on one side in three consec ⁇ utive steps and as taught by the invention.
  • Example 1 Example 1
  • the means of Fig. 2 was used to coat LVC base paper; the base paper's basis weight was about 43 g/m 2 , density about 618 kg/m 3 , roughness about 360 ml/min., opacity about 87%.
  • precoat was applied on the surface of the web with the aid of the coating means and in the second step (2) , face coating with the aid of the second coating means.
  • the coating material used in step (1) was 100% carbo ⁇ nate; the coating material used in step (2) contained 10% plastic pigment (Rhodopas) and 90% SPS kaolin.
  • the following characteristics of the coated paper were de ⁇ termined: basis weight, density, roughness and gloss.
  • step (1) 1 0 0% carbonate was applied on the web and in step (2) , coating material containing 30% plastic pigment and 70% SPS kaolin.
  • step (1) 100% carbo ⁇ nate was applied on the web and in step (2) , coating material containing 50% plastic pigment and 50% SPS kaolin.
  • step (l) coating mate ⁇ rial containing 10% starch was applied on the web and in step (2) , coating material containing 100% SPS kaolin.

Landscapes

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

Abstract

Procédé d'enduction d'une bande de papier en au moins deux étapes, la seconde étape étant exécutée immédiatement après la première de sorte que la couche d'enduit appliquée et raclée dans la première étape n'a pas le temps de sécher avant l'exécution de la seconde étape.
EP19890913225 1988-12-07 1989-12-07 Procede et moyen d'enduction d'une bande de papier en au moins deux etapes Withdrawn EP0447420A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI885678 1988-12-07
FI885678A FI885678A (fi) 1988-12-07 1988-12-07 Foerfarande och anordning foer belaeggning av en pappersbana i aotminstone tvao steg.

Publications (1)

Publication Number Publication Date
EP0447420A1 true EP0447420A1 (fr) 1991-09-25

Family

ID=8527531

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890913225 Withdrawn EP0447420A1 (fr) 1988-12-07 1989-12-07 Procede et moyen d'enduction d'une bande de papier en au moins deux etapes

Country Status (4)

Country Link
EP (1) EP0447420A1 (fr)
JP (1) JPH04503918A (fr)
FI (1) FI885678A (fr)
WO (1) WO1990006184A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI86318C (fi) * 1990-06-26 1992-08-10 Keskuslaboratorio Foerfarande och anordning foer att reglera bladbestrykning.
DE4208295A1 (de) * 1992-03-16 1993-09-23 Roland Man Druckmasch Einfaerbevorrichtung fuer eine rasterwalze
US6077352A (en) * 1992-09-02 2000-06-20 Consolidated Papers, Inc. Mounting assembly for a single backing roll coating station
DE59305498D1 (de) * 1993-02-04 1997-03-27 Voith Gmbh J M Vorrichtung zum Auftragen von Streichfarbe auf eine Faserstoffbahn
DE19723458A1 (de) 1997-06-04 1998-12-10 Voith Sulzer Papiermasch Gmbh Vorrichtung und Verfahren zum Auftragen eines flüssigen oder pastösen Mediums auf einen sich vorbeibewegenden Untergrund
DE19905935A1 (de) * 1999-02-12 2000-08-17 Beiersdorf Ag Verfahren zur Herstellung einer Beschichtung von lösungsmittelfreien Haftklebesystemen auf insbesondere releasebeschichteten Substraten

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3474757A (en) * 1965-10-24 1969-10-28 Donald F Dreher Multiple coating apparatus
JPS58205561A (ja) * 1982-05-25 1983-11-30 Fuji Photo Film Co Ltd 塗布方法及び装置
US4477495A (en) * 1982-11-09 1984-10-16 International Paper Company Method and apparatus for preparing thermoplastic coated webs and products thereof
FI81734C (fi) * 1987-12-03 1990-12-10 Valmet Paper Machinery Inc Foerfarande och anordning foer applicering och dosering av bestrykningsmedel pao roerligt underlag.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9006184A1 *

Also Published As

Publication number Publication date
WO1990006184A1 (fr) 1990-06-14
FI885678A (fi) 1990-06-08
JPH04503918A (ja) 1992-07-16
FI885678A0 (fi) 1988-12-07

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