CA1095345A - Processes and apparatus for coating paper and cardboard and an apparatus for performing them - Google Patents
Processes and apparatus for coating paper and cardboard and an apparatus for performing themInfo
- Publication number
- CA1095345A CA1095345A CA280,637A CA280637A CA1095345A CA 1095345 A CA1095345 A CA 1095345A CA 280637 A CA280637 A CA 280637A CA 1095345 A CA1095345 A CA 1095345A
- Authority
- CA
- Canada
- Prior art keywords
- coating
- strip
- blades
- paper
- cardboard
- 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.)
- Expired
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
- 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
-
- 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
-
- 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
- D21H5/00—Special paper or cardboard not otherwise provided for
- D21H5/0005—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating
- D21H5/006—Controlling or regulating
- D21H5/0062—Regulating the amount or the distribution, e.g. smoothing, of essentially fluent material already applied to the paper; Recirculating excess coating material applied to paper
- D21H5/0065—Regulating the amount or the distribution, e.g. smoothing, of essentially fluent material already applied to the paper; Recirculating excess coating material applied to paper with blades
Landscapes
- Paper (AREA)
- Coating Apparatus (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Containers And Packaging Bodies Having A Special Means To Remove Contents (AREA)
Abstract
IMPROVEMENT TO PROCESSES AND APPARATUS FOR COATING PAPER
AND CARDBOARD AND AN APPARATUS FOR PERFORMING THEM
Abstract of the Disclosure The thickness of the coating of an aqueous compo-sition deposited in excess on a continuous strip of paper or cardboard supported by the lateral surface of a cylinder is regulated and regularized by removing the excess substance by scraping by means of at least two successively acting blades. The process makes it possible to obtain coatings of regular thickness, which are free from streaks and furrows, corresponding to quantities of dry material which are generally below 15 g/m2 to as low as 5 g/m2 without decreasing the viscosity of the coating baths.
AND CARDBOARD AND AN APPARATUS FOR PERFORMING THEM
Abstract of the Disclosure The thickness of the coating of an aqueous compo-sition deposited in excess on a continuous strip of paper or cardboard supported by the lateral surface of a cylinder is regulated and regularized by removing the excess substance by scraping by means of at least two successively acting blades. The process makes it possible to obtain coatings of regular thickness, which are free from streaks and furrows, corresponding to quantities of dry material which are generally below 15 g/m2 to as low as 5 g/m2 without decreasing the viscosity of the coating baths.
Description
~53~;
S P E C I F I C A T I O N
The present invention relates to processes for coating papers and cardboards. It is addressed more particularly at a continuous process for regulating and regularizing the thickness of the coating of an aqueous 5 composition deposited in excess on a conti llUOUS strip of paper or cardboard supported by the lateral surface of a cylinder, whereby the excess coated subst~nce is removed by scraping. It also relates to an apparatus permit~ing the performance o~ said process and to the coated papers and cardboards obtained by said process.
It is known that, in principle, aqueous composi-tions for coating paper and cardboard contain pigments and binders. The most freguently used pigment is mineral clay.
In a small proportion comparad with the mineral clay, it is 1~ also possible to use other pi~ments such as calcium car-bonate, titanium oxide, hydrargillite~ talc~ barium sù~phate, etc. Thes~ pigments are dispersed in water, generally in an alkaline medium and in the presence of dispersing agents, the most important of which are tetrasodium pyrophosphate,
S P E C I F I C A T I O N
The present invention relates to processes for coating papers and cardboards. It is addressed more particularly at a continuous process for regulating and regularizing the thickness of the coating of an aqueous 5 composition deposited in excess on a conti llUOUS strip of paper or cardboard supported by the lateral surface of a cylinder, whereby the excess coated subst~nce is removed by scraping. It also relates to an apparatus permit~ing the performance o~ said process and to the coated papers and cardboards obtained by said process.
It is known that, in principle, aqueous composi-tions for coating paper and cardboard contain pigments and binders. The most freguently used pigment is mineral clay.
In a small proportion comparad with the mineral clay, it is 1~ also possible to use other pi~ments such as calcium car-bonate, titanium oxide, hydrargillite~ talc~ barium sù~phate, etc. Thes~ pigments are dispersed in water, generally in an alkaline medium and in the presence of dispersing agents, the most important of which are tetrasodium pyrophosphate,
2~ sodium hex~netaphosphate and low molecular weight polyacry-lates in quantities between 0.2 and 0.5% by weight of the pigments. These pigment~ are fîxed to the paper or card-board by means of bindexs. Generally, the binders consist of an aqueou.s dispersion of a synthetic polymer, such as a styrene/butadieile copolymer, an acrylic polymer or a vinyl acetate polymer, either used alone or mixed with natural binders such as ~tarches, proteins or casein or synthetic ~inders, such as polyvinyl alcohols. It is gener2Lly ~os-sible to mix the agueous dispersions to includè ingre~ients
3 ~llich are able to improve the water retention properties o~
3~
the roating compositions, such as carboxymethyl cellulos~s `~ or alginates~ Finally, the coating compositions can contain various other ingredients, such as cross-linkin~ ayents, anti-foaming agents, lubricants, optical briglltening agents and coloring agents.
A paper or cardboard coating process is known in which, on one of the faces of a paper or cardboard strip, an excess auantity of the a~ueous composition is continuously deposited, generally by means of a coating roller. The 1~ excess material is then removed by scrapin~ by means of a so-called smoothing roller. The coating speed is generally between 300 and 1500m/min. The quantities of aqueous compo~
~ition deposited on the paper or cardboard by the coating roller are gen~rally between 200 and 800 g/m2. Depending on the rigidity of the blade, the pressurs which is applied thereto, the distance between the blade and the paper or cardboard, the compressibility of the paper or cardboard, ; and the rheological properties of the coating kath, the quantity of material deposited on the paper or cardboard a~ter drying the coating can vary between 6 and 15 g,~m2.
When coating in accordance with the described processO straaks can occur on the coating as a result of particles having a size greater than the distance between the blade and the paper or cardboard, whereby said particles jam between the blade and the paper or cardboard. These particles may come from the coating bath or may comprise various aggre-gates, such as clots or sticks present on the surface of the paper or cardboard. It is also possible to observe defects in the uni~ormity of the coating spread on the sur-face of the pap~r or cardboard, such as furrows and projection~
,.
3~
often due to irregularities in the paper or cardboard. They are made all the more readily visible due to -the fact that, during the coating opexation, turbulence occurs in -the excess coa-ting which the blade is required to remove by scraping.
The process forming the object of the present invention makes it possible, in an unexpect:ed manner~ signific-antly to reduce these disadvantagesO
According to the process of the invention, scraping is performed by at least two successively acting blades. The final blade is called the smoothing blade and the other blade or blades are called preme-tering blades. In practice, the number oE blades is at the most equal to four.
Accordingly the present invention provides a process for applying a smooth~ uniform coating onto a continuous strip of paper or cardboard, the improvement wherein the thick-ness of the coating is continually regulated by depositing an excess of the coating composition onto the strip while the back side of the strip is being supported, and rPmoving excess coating by engagement of the coated surface with at least two successive scraper blades which extend crosswise of the strip.
The present invention also provides papers and ca~boards having a coating of an aqueous composition in which the coating is characterized by a regular thickness, is free from furrows and streaks and corresponds -to a ~uantity of dry solids between 15 g/m2 to 5 g/m2.
q~o prevent a reduction in the quantity of water by absorption through the paper or cardboard or by evaporation in the air when passing from the first to last blade, the distance between said two blades should be as small as possible. Such reduction in the quantity of water could also lead to streaks " ~.3 , ~ ~ , ~ 53~S
caused by expansion in con-tact with the final blade. In practice, the distance between the free ends of the first and last blades applied against the coating of aqueous composition is generally between 0.2 and 50 centimeters.
In order to bring about a maximum improvement of spread-ing and reduce to the greatest possible extent the risks of streaks being formed, the distance betweell the first blade and -the strip is xegulated in such a way that the weight of the coating left on the strip by said blade, expressed in dry solids, is between 10 and 50 g/m .
~ - 3a -`~:
In order to permit a completely satisfactory perormance of the invention, each or the hlades i~ inclined relative to the strip ~y an angle within the range of 5 to 60.
The process according to the inv~ntion makes it po~sible to obtain coatings of regular thi.ckness, which are frae ~rom streaks and furrows, in which the quantity of dry solids is generally below 15 ~/m~ and which go as low as 5 g/m2 witho~t decreasing the viscosity of the coating baths.
It is ound that through the use of 3 or 4 blades, a coating : with a better appearance is generally obtained than when using only two blades.
A machine for realizing the process of the inven-tion in the production of coated paper or cardboard com-prises at least one assemb3.y having a supporting cylinder (or more commonly a supporting surace~ on the outer surface of which is displaced a continuous strip of paper or card-board~ and a wetting or coating roller which serves to transfer to said paper or cardboard strip a coating of an aqueous composition supplied from a suitable reservoir.
The apparatus Eorming the object of the invention : ~or regulating and regularlzing the thickness of the coating of aqueous composition deposited in excess on a continuous paper or cardboard strip suppcrted by the la eral surface o~
a cylinder o~ a paper or cardboard coating machine comprises at least two successively arranged blade~, of which one of the ends lS free and appli2d to the aqueous composition coating. It a~so advantageously comprises means for regu-lating the slope of each of the blades relat.ive to the strip 3 and means .or regulating the distance of each o~ the blades .
., 3~
from the strip. The number of blades ls generally at the rnost equal to four.
For a satisfactory performance of the invention, the distance ketween the free end~ of the first and final blades applied against the aqueous ~omposition coating is ~etween 0.~ and 50 centimeters.
A detailed clescription of an em~odiment of the apparatus of the invention will hereinaf-ter be described with reference to Figs. 1 to 4, in which:
Fig. 1 is a schematic elevation view of a paper or cardboard coating machine partially in section, equipped with the apparatus according to the invention.
Fig. 2 is a side view of the apparatus mounted on the coating rllachine.
Fig. 3 is a ront view of the apparatus mounted on the coating machine.
Fig. 4 is a plan view of the apparatus mounted on the coating machine.
The apparatus forms part of a conventional paper or cardboard coating machine, whereof the main compo-nents are shown schematically in Fig. 1. This machine substantially comprises a supporting cylinder 1 which rotates in the direction of the arrow about axis 0. On ; the outer surface of supporting cylinder 1 is wound a 2~ continuous strlp of paper or cardboard 2 supplied from a reel (not shown~ This strip is caused to bear on the supporting cylinder in accordance with a ~iven windir.g arc by an appropriate conventional device, for example one or several tension rollers 3.
A rotary coating rcller 4 is part~ally submerged 5~
in a bath 5 of an a~ueo-ls composition ~ontained in a reservoir 6 while the uppar surface tarlgentially engages th~ strip in such a way that during its rotational movement, it transfers a coating 4a of a~ueous composition, to the surface o strip 2~ Fig. 1 shows an appropriate relative position of coating roller 4 below supporting cylinder 1, ~ut it is obvious that any random appropriate relative position can be adopted. Moreover, a number of coating rollexs can be associated with the supporting cylinder 1, whereby each of them is able to transfer a given quantity of aqueous composition to strip 2 The aqueous composition can be any of a number :~
of well known composition suitable for giving a suitable coating to stxip 2 and normally contains one or more pigme`nts, such as for example kaolin, cal~ium carbonate, ~;:
titanium oxide, hydrargil-lite, talc,barium sulphate and one or more binders, such as for example synthetic poly-mers, starches, proteins or casein. The solids content of the composition is between 50 and 65% by weight.
The regulating apparatus 7 according to the invention is located on the periphery of strip 2 downstream of coating roller 4. It has a vertical plane of symmetry perpendicular to rotation axis 0 of supporting cylinder 1.
This apparatus essentially comprises two scraping blades 8 and 9, whereby one of the ends thereof is applied against strip 2, respectively at points P a~d Q. Blades 8 and 9 are respectively fixed at their other end to blade holders 10 and 11 by means of screws such as 12.
Blade holders 10 and 11 are respectively articulated ~ith 3 supports 13 and 14 in such a way that each of thei.r two 3~i ends, provided t~ith a guidance me~ber 15, can move in a direction orthogonal to axis 0 within a slot 16 made in the corresponding support. I~nurled buttons 17 and 18 mounted respectively on supports 13 and 14 permit, by means of conventional mechanical means not shown, the sliding and maintalning in position of guidance members 15 in windows 19 made in slots 16 and thus regulate the distance b~tween each of the blades 8 and 9 on the one hand and the strip 2 on the other.
Each support is provided with two trunnions 20 engaged in recesses 21 made in side plates 22, permitting the pivoting thereof about an axis parallel to axis 0.
In this way, it i5 possihle to adjust the blades 8 and 9 to the d~sired angle of inclination relative to strip 20 Side plates 22 are interconnected by bars 23 and 24 maln-tained in position by nut members 25 and 26~
Side plates 22 are mounted for pivotal movement about shaft 27 parallel to axis 0 and are carrie~ by mambers 28 integral ~ith the rame 29 of the coating machine.
Slde plates 22 are fixed in position by assembly with mem-bers 28 by means of screws 30. Stops 31, carried by side plates 2 , prevent blades 8 and 9 from striking supporting cylinder 1 during the assembly o~ the apparatus on the coating machine. For reasons of clarity9 bars 23 and 24, nuts 25 and 26, members 28 and frame 29 are not shown in Fig~ 4.
Locking pins 32 and 33, located in recesses, ~uch as 34, in support3 13 and 14, make it possible to maintain said supports and consequently blades ~ and 9 in the selected inclined position corresponding to an angle ;3~
~f 30, 35, 40 or 45 degrees re7ative to strip 20 For this purpose, the locking plns 32 and 33 are respectively engaged and maintained in the engagement position i.n recesses 35 and 36 in side plate~ 22 by means of knurled buttons 37 and 38 which are able to slide in openings 39 and 40 provided in recesses, such as 34~
Hereinafter, several examples for performing the process of the invention are given.
Examples l to 5 An aqueous coating compos-ition is prepared containing the constituents and amounts by weight shown hereinafter:
Kaolin.O.............. O........................... 100 Sodium hexametaphosphate.~................ .Ø4 Car~oxylated butadiene/styrene copo'ymer.. 4 14 Carboxymethyl cellulose.... `.... ~................. .Ø4 The coating composition is brQught to a p~ of 8.5 by adding ammonia and is a~justed in such a way that it contains 60% by weight of dry solids.
~ A quantity in excess of the coating composition is deposited continuously on one of the faces of a strip of paper, o~ 74 g/m~, by means of a coating roller then, by scraping by means o one or several blades whose inclina-tion angle relative to the strip i5 regulated to 30 degrees, ~5 the excess coating is removed in such a way that a roating layer of g g/m2, expressed in dry s~bstance is obtained.
The thus coated paper is dried in a tunnel furnace at a temperature of 100C, then undergoes calendaring con-sisting of being passed four times in succession between two cylinders under a load of 80 kg/cm.
~ 33 ~ ~
In example l, which i5 given for comparison purposes, a single scraping blade is used.
In examples 2, 3, 4 and 5, illustrative of the practice of khis invention, an apparatus is used which has a premetering blade and a smoothing blacle. The distance between the free ends of the premeterinq blade and the smoothing blade i5 regulated to 2cm and the position o~ the premetering blade is regulated in such a way that the weight of the coating let by said blade, expressed in dry solids is respectively-12, 20, 25 and 4~ g/m2~
The spreading quality is evaluated by means of the so-called "Microcontour test", whose principle is as follows: An ink formed from a course grained pigment is dispersed in an oil of average viscosity, marketed by Etablissements ~or illeux Lefranc under the name "ink for microcontour test", is deposited in excess on the paper. ~s the plgment particle dimensions are greater than the diameter of the paper pores, the pigment cannot penetrate into the paper~ After appropriate wiping, the quantlty of pigment Ieft on the paper increases in propor-tion to the roughness of the paper.
The coloring intensity obtained thus makes it possible to evaluate roughness and also the size of the furrows.
~5 Table l gives the results obtained in each of the ex~mples.
Table 1 Example l¦Example ~ Example 31 xample 4 Example 5 ~ ~._ ,. ~
Coloriny Relatively Small Small Small Relatively Intenslty High _ _ Small . ., _ _ _ --9 _ 53~5 ~t can he seen that the use of pre~etering blade leads to coa~ed papers with reduced roughness.
Exam~les 6 to 9 The operation is carried out under the same conditions as in examples 2 to 5, but using an apparatus -~
having two premetering blades and one smoothing blade.
The distance between the free ends of the two premetering blades is regulated to 2cm and the distance between the free ends of the second premetering blade and the smoothing blade is also regulated to 2cm. The position of the `7 premetering blade is regulated in such a way that the weight of the eoating le~t be~ind by said blades, expressed in dry material is as indicated in Table 2.
- Table 2 15 - ¦Ex~mple 5 ExamplP 7 Example 8iExample 9 . . , .. . . - _ .
Coating weight le~t . .
by first premetering .
blade (g/m2) 20 30 45 65 _ Coating weight left . ¦
by seccnd premetering . I
blade (g/m2) 1~ ¦ 20 25 48 .
The microcontour test shows that the coloring intensity and consequently the roughn ss of the coated papers obtained are smaller than those of the coated papers obtained in examples 2 to 4.
3~
~ 10 --
3~
the roating compositions, such as carboxymethyl cellulos~s `~ or alginates~ Finally, the coating compositions can contain various other ingredients, such as cross-linkin~ ayents, anti-foaming agents, lubricants, optical briglltening agents and coloring agents.
A paper or cardboard coating process is known in which, on one of the faces of a paper or cardboard strip, an excess auantity of the a~ueous composition is continuously deposited, generally by means of a coating roller. The 1~ excess material is then removed by scrapin~ by means of a so-called smoothing roller. The coating speed is generally between 300 and 1500m/min. The quantities of aqueous compo~
~ition deposited on the paper or cardboard by the coating roller are gen~rally between 200 and 800 g/m2. Depending on the rigidity of the blade, the pressurs which is applied thereto, the distance between the blade and the paper or cardboard, the compressibility of the paper or cardboard, ; and the rheological properties of the coating kath, the quantity of material deposited on the paper or cardboard a~ter drying the coating can vary between 6 and 15 g,~m2.
When coating in accordance with the described processO straaks can occur on the coating as a result of particles having a size greater than the distance between the blade and the paper or cardboard, whereby said particles jam between the blade and the paper or cardboard. These particles may come from the coating bath or may comprise various aggre-gates, such as clots or sticks present on the surface of the paper or cardboard. It is also possible to observe defects in the uni~ormity of the coating spread on the sur-face of the pap~r or cardboard, such as furrows and projection~
,.
3~
often due to irregularities in the paper or cardboard. They are made all the more readily visible due to -the fact that, during the coating opexation, turbulence occurs in -the excess coa-ting which the blade is required to remove by scraping.
The process forming the object of the present invention makes it possible, in an unexpect:ed manner~ signific-antly to reduce these disadvantagesO
According to the process of the invention, scraping is performed by at least two successively acting blades. The final blade is called the smoothing blade and the other blade or blades are called preme-tering blades. In practice, the number oE blades is at the most equal to four.
Accordingly the present invention provides a process for applying a smooth~ uniform coating onto a continuous strip of paper or cardboard, the improvement wherein the thick-ness of the coating is continually regulated by depositing an excess of the coating composition onto the strip while the back side of the strip is being supported, and rPmoving excess coating by engagement of the coated surface with at least two successive scraper blades which extend crosswise of the strip.
The present invention also provides papers and ca~boards having a coating of an aqueous composition in which the coating is characterized by a regular thickness, is free from furrows and streaks and corresponds -to a ~uantity of dry solids between 15 g/m2 to 5 g/m2.
q~o prevent a reduction in the quantity of water by absorption through the paper or cardboard or by evaporation in the air when passing from the first to last blade, the distance between said two blades should be as small as possible. Such reduction in the quantity of water could also lead to streaks " ~.3 , ~ ~ , ~ 53~S
caused by expansion in con-tact with the final blade. In practice, the distance between the free ends of the first and last blades applied against the coating of aqueous composition is generally between 0.2 and 50 centimeters.
In order to bring about a maximum improvement of spread-ing and reduce to the greatest possible extent the risks of streaks being formed, the distance betweell the first blade and -the strip is xegulated in such a way that the weight of the coating left on the strip by said blade, expressed in dry solids, is between 10 and 50 g/m .
~ - 3a -`~:
In order to permit a completely satisfactory perormance of the invention, each or the hlades i~ inclined relative to the strip ~y an angle within the range of 5 to 60.
The process according to the inv~ntion makes it po~sible to obtain coatings of regular thi.ckness, which are frae ~rom streaks and furrows, in which the quantity of dry solids is generally below 15 ~/m~ and which go as low as 5 g/m2 witho~t decreasing the viscosity of the coating baths.
It is ound that through the use of 3 or 4 blades, a coating : with a better appearance is generally obtained than when using only two blades.
A machine for realizing the process of the inven-tion in the production of coated paper or cardboard com-prises at least one assemb3.y having a supporting cylinder (or more commonly a supporting surace~ on the outer surface of which is displaced a continuous strip of paper or card-board~ and a wetting or coating roller which serves to transfer to said paper or cardboard strip a coating of an aqueous composition supplied from a suitable reservoir.
The apparatus Eorming the object of the invention : ~or regulating and regularlzing the thickness of the coating of aqueous composition deposited in excess on a continuous paper or cardboard strip suppcrted by the la eral surface o~
a cylinder o~ a paper or cardboard coating machine comprises at least two successively arranged blade~, of which one of the ends lS free and appli2d to the aqueous composition coating. It a~so advantageously comprises means for regu-lating the slope of each of the blades relat.ive to the strip 3 and means .or regulating the distance of each o~ the blades .
., 3~
from the strip. The number of blades ls generally at the rnost equal to four.
For a satisfactory performance of the invention, the distance ketween the free end~ of the first and final blades applied against the aqueous ~omposition coating is ~etween 0.~ and 50 centimeters.
A detailed clescription of an em~odiment of the apparatus of the invention will hereinaf-ter be described with reference to Figs. 1 to 4, in which:
Fig. 1 is a schematic elevation view of a paper or cardboard coating machine partially in section, equipped with the apparatus according to the invention.
Fig. 2 is a side view of the apparatus mounted on the coating rllachine.
Fig. 3 is a ront view of the apparatus mounted on the coating machine.
Fig. 4 is a plan view of the apparatus mounted on the coating machine.
The apparatus forms part of a conventional paper or cardboard coating machine, whereof the main compo-nents are shown schematically in Fig. 1. This machine substantially comprises a supporting cylinder 1 which rotates in the direction of the arrow about axis 0. On ; the outer surface of supporting cylinder 1 is wound a 2~ continuous strlp of paper or cardboard 2 supplied from a reel (not shown~ This strip is caused to bear on the supporting cylinder in accordance with a ~iven windir.g arc by an appropriate conventional device, for example one or several tension rollers 3.
A rotary coating rcller 4 is part~ally submerged 5~
in a bath 5 of an a~ueo-ls composition ~ontained in a reservoir 6 while the uppar surface tarlgentially engages th~ strip in such a way that during its rotational movement, it transfers a coating 4a of a~ueous composition, to the surface o strip 2~ Fig. 1 shows an appropriate relative position of coating roller 4 below supporting cylinder 1, ~ut it is obvious that any random appropriate relative position can be adopted. Moreover, a number of coating rollexs can be associated with the supporting cylinder 1, whereby each of them is able to transfer a given quantity of aqueous composition to strip 2 The aqueous composition can be any of a number :~
of well known composition suitable for giving a suitable coating to stxip 2 and normally contains one or more pigme`nts, such as for example kaolin, cal~ium carbonate, ~;:
titanium oxide, hydrargil-lite, talc,barium sulphate and one or more binders, such as for example synthetic poly-mers, starches, proteins or casein. The solids content of the composition is between 50 and 65% by weight.
The regulating apparatus 7 according to the invention is located on the periphery of strip 2 downstream of coating roller 4. It has a vertical plane of symmetry perpendicular to rotation axis 0 of supporting cylinder 1.
This apparatus essentially comprises two scraping blades 8 and 9, whereby one of the ends thereof is applied against strip 2, respectively at points P a~d Q. Blades 8 and 9 are respectively fixed at their other end to blade holders 10 and 11 by means of screws such as 12.
Blade holders 10 and 11 are respectively articulated ~ith 3 supports 13 and 14 in such a way that each of thei.r two 3~i ends, provided t~ith a guidance me~ber 15, can move in a direction orthogonal to axis 0 within a slot 16 made in the corresponding support. I~nurled buttons 17 and 18 mounted respectively on supports 13 and 14 permit, by means of conventional mechanical means not shown, the sliding and maintalning in position of guidance members 15 in windows 19 made in slots 16 and thus regulate the distance b~tween each of the blades 8 and 9 on the one hand and the strip 2 on the other.
Each support is provided with two trunnions 20 engaged in recesses 21 made in side plates 22, permitting the pivoting thereof about an axis parallel to axis 0.
In this way, it i5 possihle to adjust the blades 8 and 9 to the d~sired angle of inclination relative to strip 20 Side plates 22 are interconnected by bars 23 and 24 maln-tained in position by nut members 25 and 26~
Side plates 22 are mounted for pivotal movement about shaft 27 parallel to axis 0 and are carrie~ by mambers 28 integral ~ith the rame 29 of the coating machine.
Slde plates 22 are fixed in position by assembly with mem-bers 28 by means of screws 30. Stops 31, carried by side plates 2 , prevent blades 8 and 9 from striking supporting cylinder 1 during the assembly o~ the apparatus on the coating machine. For reasons of clarity9 bars 23 and 24, nuts 25 and 26, members 28 and frame 29 are not shown in Fig~ 4.
Locking pins 32 and 33, located in recesses, ~uch as 34, in support3 13 and 14, make it possible to maintain said supports and consequently blades ~ and 9 in the selected inclined position corresponding to an angle ;3~
~f 30, 35, 40 or 45 degrees re7ative to strip 20 For this purpose, the locking plns 32 and 33 are respectively engaged and maintained in the engagement position i.n recesses 35 and 36 in side plate~ 22 by means of knurled buttons 37 and 38 which are able to slide in openings 39 and 40 provided in recesses, such as 34~
Hereinafter, several examples for performing the process of the invention are given.
Examples l to 5 An aqueous coating compos-ition is prepared containing the constituents and amounts by weight shown hereinafter:
Kaolin.O.............. O........................... 100 Sodium hexametaphosphate.~................ .Ø4 Car~oxylated butadiene/styrene copo'ymer.. 4 14 Carboxymethyl cellulose.... `.... ~................. .Ø4 The coating composition is brQught to a p~ of 8.5 by adding ammonia and is a~justed in such a way that it contains 60% by weight of dry solids.
~ A quantity in excess of the coating composition is deposited continuously on one of the faces of a strip of paper, o~ 74 g/m~, by means of a coating roller then, by scraping by means o one or several blades whose inclina-tion angle relative to the strip i5 regulated to 30 degrees, ~5 the excess coating is removed in such a way that a roating layer of g g/m2, expressed in dry s~bstance is obtained.
The thus coated paper is dried in a tunnel furnace at a temperature of 100C, then undergoes calendaring con-sisting of being passed four times in succession between two cylinders under a load of 80 kg/cm.
~ 33 ~ ~
In example l, which i5 given for comparison purposes, a single scraping blade is used.
In examples 2, 3, 4 and 5, illustrative of the practice of khis invention, an apparatus is used which has a premetering blade and a smoothing blacle. The distance between the free ends of the premeterinq blade and the smoothing blade i5 regulated to 2cm and the position o~ the premetering blade is regulated in such a way that the weight of the coating let by said blade, expressed in dry solids is respectively-12, 20, 25 and 4~ g/m2~
The spreading quality is evaluated by means of the so-called "Microcontour test", whose principle is as follows: An ink formed from a course grained pigment is dispersed in an oil of average viscosity, marketed by Etablissements ~or illeux Lefranc under the name "ink for microcontour test", is deposited in excess on the paper. ~s the plgment particle dimensions are greater than the diameter of the paper pores, the pigment cannot penetrate into the paper~ After appropriate wiping, the quantlty of pigment Ieft on the paper increases in propor-tion to the roughness of the paper.
The coloring intensity obtained thus makes it possible to evaluate roughness and also the size of the furrows.
~5 Table l gives the results obtained in each of the ex~mples.
Table 1 Example l¦Example ~ Example 31 xample 4 Example 5 ~ ~._ ,. ~
Coloriny Relatively Small Small Small Relatively Intenslty High _ _ Small . ., _ _ _ --9 _ 53~5 ~t can he seen that the use of pre~etering blade leads to coa~ed papers with reduced roughness.
Exam~les 6 to 9 The operation is carried out under the same conditions as in examples 2 to 5, but using an apparatus -~
having two premetering blades and one smoothing blade.
The distance between the free ends of the two premetering blades is regulated to 2cm and the distance between the free ends of the second premetering blade and the smoothing blade is also regulated to 2cm. The position of the `7 premetering blade is regulated in such a way that the weight of the eoating le~t be~ind by said blades, expressed in dry material is as indicated in Table 2.
- Table 2 15 - ¦Ex~mple 5 ExamplP 7 Example 8iExample 9 . . , .. . . - _ .
Coating weight le~t . .
by first premetering .
blade (g/m2) 20 30 45 65 _ Coating weight left . ¦
by seccnd premetering . I
blade (g/m2) 1~ ¦ 20 25 48 .
The microcontour test shows that the coloring intensity and consequently the roughn ss of the coated papers obtained are smaller than those of the coated papers obtained in examples 2 to 4.
3~
~ 10 --
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for applying a smooth, uniform coating onto a continuous strip of paper or cardboard, the improvement wherein the thickness of the coating is continually regulated by depositing an excess of the coating composition onto the strip while the back side of the strip is being supported, and removing excess coating by engagement of the coated surface with at least two successive scraper blades which extend crosswise of the strip.
2. A process as claimed in Claim 1, in which the support for the strip comprises a revolving cylinder which is engaged over a portion of its periphery by the strip.
3. A process as claimed in Claim 1, in which the coating composition is an aqueous coating composition.
4. A process as claimed in Claim 1, in which the number of blades does not exceed four.
5. A process as claimed in Claim 1, in which the distance between the free ends of the first and last of the blades in engagement with the composition coating is between 0.2 and 50 centimeters.
6. A process as claimed in Claim 1, in which the distance between the first blade and the strip is calculated such that the weight of the coating left on the strip by said blade, expressed in dry solids by weight, is between 10 and 50 g/m2.
7. A process as claimed in Claim 1, in which each of the blades is inclined relative to the strip at an angle within the range of 5 to 60 degrees.
8. Papers and cardboards having a coating of an aqueous composition in which the coating is characterized by a regular thickness, is free from furrows and streaks and corresponds to a quantity of dry solids between 15 g/m2 to 5 g/m2.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7618598A FR2355119A1 (en) | 1976-06-18 | 1976-06-18 | IMPROVEMENT OF PAPER AND BOARD COATING PROCESSES AND DEVICE FOR ITS IMPLEMENTATION |
| FR76.18598 | 1976-06-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1095345A true CA1095345A (en) | 1981-02-10 |
Family
ID=9174595
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,637A Expired CA1095345A (en) | 1976-06-18 | 1977-06-16 | Processes and apparatus for coating paper and cardboard and an apparatus for performing them |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS52155644A (en) |
| BE (1) | BE855842A (en) |
| BR (1) | BR7703918A (en) |
| CA (1) | CA1095345A (en) |
| CH (1) | CH621167A5 (en) |
| DE (1) | DE2726994C3 (en) |
| DK (1) | DK270177A (en) |
| ES (1) | ES459806A1 (en) |
| FI (1) | FI771890A (en) |
| FR (1) | FR2355119A1 (en) |
| GB (1) | GB1549915A (en) |
| NL (1) | NL7706717A (en) |
| NO (1) | NO772123L (en) |
| PT (1) | PT66680B (en) |
| SE (1) | SE7707072L (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2427847A2 (en) * | 1978-06-08 | 1980-01-04 | Sireix Georges | DEVICE FOR BONDING MATERIALS IN STRIPS |
| FR2445228A1 (en) * | 1978-12-29 | 1980-07-25 | Cii Honeywell Bull | SQUEEGEE HOLDER FOR PRINTING APPARATUS |
| DE3633833C1 (en) * | 1986-10-04 | 1993-05-06 | Vits Maschinenbau Gmbh | Method and device for applying a liquid or pasty substance to a material web |
| JPH0523046Y2 (en) * | 1986-10-14 | 1993-06-14 | ||
| FI81637C (en) * | 1988-01-29 | 1990-11-12 | Valmet Paper Machinery Inc | Device for coating material web |
| DE102004007927A1 (en) * | 2004-02-18 | 2005-09-01 | Basf Ag | Chemically different flowable material application process to produce adhesive systems, paints and coatings on substrate involves use of multi-cascade nozzle for simultaneous deposition of several layers |
| CN112844943A (en) * | 2019-11-27 | 2021-05-28 | 苏州维业达触控科技有限公司 | Fill out and scrape equipment and fill out and scrape subassembly thereof |
| CN112827739A (en) * | 2019-12-25 | 2021-05-25 | 龙南县方成科技有限公司 | Automatic glue spreading machine for inductor |
-
1976
- 1976-06-18 FR FR7618598A patent/FR2355119A1/en active Granted
-
1977
- 1977-06-15 JP JP7094077A patent/JPS52155644A/en active Granted
- 1977-06-15 ES ES459806A patent/ES459806A1/en not_active Expired
- 1977-06-15 FI FI771890A patent/FI771890A/fi not_active Application Discontinuation
- 1977-06-15 DE DE2726994A patent/DE2726994C3/en not_active Expired
- 1977-06-16 GB GB25286/77A patent/GB1549915A/en not_active Expired
- 1977-06-16 BR BR7703918A patent/BR7703918A/en unknown
- 1977-06-16 PT PT66680A patent/PT66680B/en unknown
- 1977-06-16 NO NO772123A patent/NO772123L/en unknown
- 1977-06-16 CA CA280,637A patent/CA1095345A/en not_active Expired
- 1977-06-17 NL NL7706717A patent/NL7706717A/en not_active Application Discontinuation
- 1977-06-17 CH CH747377A patent/CH621167A5/en not_active IP Right Cessation
- 1977-06-17 BE BE178567A patent/BE855842A/en unknown
- 1977-06-17 DK DK270177A patent/DK270177A/en unknown
- 1977-06-17 SE SE7707072A patent/SE7707072L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DK270177A (en) | 1977-12-19 |
| ES459806A1 (en) | 1978-04-01 |
| FI771890A (en) | 1977-12-19 |
| PT66680A (en) | 1977-07-01 |
| SE7707072L (en) | 1977-12-19 |
| NO772123L (en) | 1977-12-20 |
| BE855842A (en) | 1977-12-19 |
| DE2726994C3 (en) | 1980-07-24 |
| BR7703918A (en) | 1978-04-04 |
| FR2355119B1 (en) | 1981-09-11 |
| GB1549915A (en) | 1979-08-08 |
| CH621167A5 (en) | 1981-01-15 |
| FR2355119A1 (en) | 1978-01-13 |
| JPS52155644A (en) | 1977-12-24 |
| NL7706717A (en) | 1977-12-20 |
| DE2726994A1 (en) | 1977-12-22 |
| JPS5444289B2 (en) | 1979-12-25 |
| DE2726994B2 (en) | 1979-11-15 |
| PT66680B (en) | 1978-11-15 |
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