DE3328064A1 - Process for the manufacture of coated paper - Google Patents

Abstract

A process for the manufacture of coated paper is characterised in that, within a very short time after the application of an excess quantity of a coating slip to a raw paper, the excess coating slip is scraped off by means of a blade-coater device of the rod type or non-rod type, the coating slip having a relatively high solids concentration and containing, as pigments, kaolin and ground natural calcium carbonate having a specified particle size distribution.

Description

The invention relates to a method for production of coated or coated paper by painting or coating a base paper with a Pigments and one or more binders containing coating slip and in particular a method for the production of coated paper for printing purposes using a coating slip with a relatively high Concentration of solids used as pigments kaolin and ground Contains natural calcium carbonate with a specific particle size distribution.

In the manufacture of coated paper for printing purposes, which consists in using a pigments and binders Applying coating slip containing to a base paper and drying the coating slip results in the Use of a coating slip with a high concentration of solids from 63 to 80% by weight the advantages of facilities, energy consumption and costs of drying the coating slip applied to the base paper can be saved because it dries quickly, and that the coated paper has excellent gloss and smoothness as the coating slips before it sets moved on the rough surface of the base paper.

Blade coaters or smooth doctor coaters the stick type and the non-stick type are used for applying paints with high solids concentrations widely used at high speeds. However, there are technical problems in the high-speed application of the coating slips with a high concentration of solids and the resulting Loss of quality of the coated paper obtained

TER MEER MÜLLER STEINMEIS'tEPJ: ''.;Käbzaki; passport. . . F-;

could not be fixed yet.

If the solids concentration of a conventional coating slip is merely increased, this results poor workability and water retention of the coating, as its viscosity increases and you Flow behavior under the action of high shear forces is reduced. This can lead to difficulties such as the formation of streaks and during the application of the coating slip

10 stalactites lead. The conventional coating pastes

with improved processability, paints containing pigments such as ground natural calcium carbonate close with a relatively large average particle size (GB-PS 1 253 603) and coating slips a, the only pigment ground natural calcium carbonate in the form of fine particles with a controlled particle size distribution included (GB patent application 2 0 36 035A). However, these conventional coating slips with improved processability have the predominant disadvantage that the papers coated therewith have a reduced gloss and an impaired one Exhibit smoothness.

The blade coaters currently commonly used for applying coatings with high solids concentrations or smooth doctor coaters of the non-rod type are trailing blade coaters with a fountain applicator mechanism or roller applicators in which the coating is washed into the nip. However, these coaters have the following disadvantages:

(1) It is very difficult to achieve an even application weight as this is difficult to achieve the pressure mechanism of the blade can be controlled.

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(2) When the blade pressure to control the application weight is increased, the coated surface of the paper becomes rough and the paper can be cut and there is an impairment

5 Impairment of processability.

(3) Because the time interval between the time of applying an excess amount of the coating on the base paper and the time at which the excess coating slip is removed (which time interval hereinafter referred to as "dwell time") is large (and for example in the case of a flooded gap coating device from Beloit at a coating speed of 1000 m / min is 0.024 seconds), the coating slip penetrates the base paper, with the result that the water retention of the coating slip with high concentration is reduced by dehydration and a Gelation and uneven spreading of the coating layer is caused. Hence the deleted Surface is not uniform and there is a likelihood of defects being formed, like stripes and stalactites.

In the case of rod-type blade coaters (roll doctor coaters) there are no problems of streaking because of foreign materials and coarse Pigment particles in the coating slip are easily guided around the rotating rod by the spiral winding and cannot be held in place by the rotating rod. If, however, a coating paste with high solids concentration at high speed is applied, it is difficult to control the coating weight, so that the possibility of uneven Order exists because the force with which the

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excess coating is stripped off is not as great as in the case of blade coaters Non-rod type. In addition, the excess coating mass can reduce the water retention as a result the coating slip after the coating slip has been applied to the base paper, defects such as splashes and the like, as the residence time is long, as is the case with non-rod type blade coaters. Therefore are used for blade coaters des

Rod type (roller doctor coaters) generally coating slips with a medium viscosity and a Solids concentration of about 40 to 6 0 wt .-% used. The rod-type blade coaters are the Blade coaters of the non-rod type in view of the quality of the coated paper obtained and superior in terms of energy savings when drying the coating.

US PS proposes to overcome these disadvantages

4,250,211 discloses a method of applying a coating using a non- stick type blade coater which employs a shorter dwell time. The aim of this process is to use a coating slip with a solids concentration of less than 60% by weight. If a coating with a higher solids concentration is used in this process, the foreign particles and the coarse pigment particles will be caught by the edges of the blade and cause streaks. A rod-blade mechanism of the pond type is described in DE-PS 2,914,531. In this rod-blade mechanism of the pond type, the coating does not develop a sufficient self-cleaning effect, so that foreign materials and the like accumulate in the vicinity of the rod and the

35 can cause streaking.

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The object of the present invention is to provide a method of the type specified at the beginning, in which a coating slip with a high concentration of solids can be applied and which does not suffer from the disadvantage of the conventional methods described above suffers. It has now been shown that this object can be achieved by improving the processability a coating slip with a high solids concentration through the use of kaolin and ground natural calcium carbonate with specific particle size distribution than pigments improves, an excess The amount of coating slip containing these pigments is applied to the base paper and the excess of the coating slip after a shorter period of time after the order

15 grazes, d. H. applies a shorter dwell time.

The invention therefore relates to a method for production of coated or coated paper by painting (coating) a base paper with a pigment and one or more binders (adhesives) containing coating slip (coating color) with a relatively high Solid concentration, which is characterized is that

(A) the coating slip has a solids concentration of 40 to 80% by weight and as pigments, each based on the total pigment content, 10 to 80% by weight kaolin and

20 to 90% by weight of ground natural calcium carbonate
contains, the kaolin having a content of particles with a particle size below 1 μm of more than 50% by weight and the ground natural calcium carbonate having a content of particles with a particle size below 2 μm of 70 to 100% by weight and of particles with a particle size below 1 μm from 55 to

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95% by weight, and

(b) a time interval of 0.0005 to 0.015 seconds between the time an excess is applied Amount of coating slip on the base paper and the time of stripping off the excess Coating mass is adhered to, d. H. the residence time is 0.0005 to 0.015 seconds.

That in the coating slip according to the invention as a pigment component The kaolin used mainly contributes to the gloss and smoothness of the coated paper and has a content of particles with a particle size below 1 μm of more than 50% by weight. The amount of used Kaolins should range from TO to 80% by weight of the total pigment content. If the used Kaolin amount is less than 10 wt .-%, the coated paper is capable of the gloss or the Smoothness not satisfying. If the content is more than 80% by weight, the coating does not show good workability.

The ground natural calcium carbonate used as a further pigment component mainly contributes to processability the coating. However, if a too coarsely ground natural calcium carbonate is used If, as according to the teaching of GB-PS 1 253 603, errors such as streaks and scratches may occur at the time of the order. occur and both the gloss and smoothness of the coated paper will occur before printing as well as the ink gloss after printing. Therefore, according to the present invention, a finely ground one becomes natural calcium carbonate is used, which has a content of particles with a particle size below 2 μm from 70 to 100% by weight and preferably 80 to 100 Weight- ¥, and a content of particles with a particle size from below 1 μm from 55 to 95% by weight and preferably

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preferably from 60 to 95% by weight. The used Amount of ground natural calcium carbonate should in the range from 20 to 90% by weight of the total pigment content lie. When the amount is less than 20% by weight, If the viscosity of the coating slip is too high under high shear stress and difficulties arise at the time of application of the coating slip. if If the amount is more than 90% by weight of the total pigment content, the gloss will increase the smoothness of the painted Paper and the gloss of the ink after printing.

In the coating slip used according to the invention Kaolin and ground natural calcium carbonate are used as pigments. Optionally, the pigments can in addition to the kaolin and the ground natural calcium carbonate contain other components, such as precipitated Calcium carbonate, satin white, titanium dioxide, pyrophyllite clay, calcium sulfite, calcium sulfate, aluminum hydroxide, zinc oxide, Talc, zeolite, barium sulfate, amorphous silicon dioxide, plastic pigment, etc. It should be noted that the amount of the additional ingredients is less than 50% by weight and preferably less than 20% by weight of the total pigment content should matter.

In the coating slip according to the invention, well-known ones can be used Binders or adhesives such as the following products are used: alkali-sensitive or alkali-insensitive Binders, including styrene / butadiene copolymers, styrene / acrylic copolymers, vinyl acetate / acrylic copolymers, Ethylene / vinyl acetate copolymers, butadiene / methyl methacrylic copolymers, vinyl acetate / butyl acrylate copolymers and polyvinyl acetate; synthetic binders such as polyvinyl alcohol, maleic anhydride / styrene copolymers, Isobutene / maleic anhydride copolymers and acrylic

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acid / methyl methacrylate copolymers; and natural binders, like oxidized denatured starch, etherified starch, esterified starch, enzyme degraded starch Rapid drying of these products obtained cold water soluble starch, casein and soybean protein. To the Formation of a coating slip with a high solids concentration of above 63% by weight and good rheological properties Properties it is advantageous to use a latex of one of the copolymers mentioned either alone or together to use with the cold water soluble starch, the total binder content being in the range of 3 to 20% by weight, based on the total pigment content. The amount of other natural binders that one Show a tendency to increase the viscosity, is preferred

15 preferably kept as low as possible. Furthermore it is

possible, if necessary, to mix the coating slip with auxiliaries, such as dispersants, the viscosity modifying agents, water retention aids, Anti-foaming agents, solubilizing agents, lubricants

20 agents, dyes and agents for adjusting the pH.

Since the coating slip obtained in this way as pigments kaolin and ground natural calcium carbonate Contains their solids concentration can freely within a range of 40 to 80 wt.% can be set. Even if the solids concentration is above 6 0% by weight, the coating slip shows a low viscosity and good flow behavior under action high shear forces, so that it has good processability.

In the method according to the invention, an excess Amount of the coating by means of a blade coater of the stick type or the non-stick type

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Base paper applied, after which the excess of the coating slip is stripped off, the residence time being 0.0005 to Is 0.015 seconds, and preferably 0.001 to 0.01 seconds. In general, this application method is thereby carried out that one the distance between the application mechanism for applying the coating to the base paper and the blade or the roll scraper mechanism to scrape off the excess coating mass to 0 to about 16 cm, preferably 0 to sets about 12 cm, and more preferably 0 to about 7 cm. In the case of using a coating paste with A high solids concentration can result if a residence time of more than 0.015 seconds is used Adjust defects such as streaks and stalactites. To achieve a dwell time of less than 0.0005 seconds the coating speed must be more than 3000 m / min, which is currently under the conditions of a stable Operation is difficult to achieve.

In the method according to the invention, a blade coating device either the bar type or the non-bar type can be used. In general, preferably one Blade coater of the non-rod type used when the solids concentration of the coating is relative is high, while the stick type blade coater is preferably used when the solids concentration is relatively low. The non-rod type blade coater may be a blade or a blade have any type, for example with an inclined or curved blade. The blade coater of the Rod type is a coating device which is provided with a rod at the end of a support device, such as it is given in DE-PS 28 51 015. The rod is generally wrapped in wire, but can even a smooth round rod without such a winding

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be ment. In general, the rod is designed to rotate. The direction of rotation can be the same or opposite to the direction of movement of the base paper.
5

According to the invention, the coating slip can be applied in a stable manner to one or both surfaces of the base paper. The application weight per side can be set within a wide range from 3 to 30 g / m ² (dry weight). When the order weight
however, is less than 5 g / m ² , the coated paper obtained does not show sufficient properties in terms of gloss, smoothness or ink gloss after printing. If the application weight is above 30 g / m ² , streaks or scratches may occur. Therefore, according to the invention, the application weight is preferably in the range from 5 to 30 g / m ² and even more preferably in the range from 8 to 20 g / m ² . Of course, you can apply the coating once (single coat) or twice (double coat). The base paper to which the coating slip is applied according to the invention
can be a base paper for coated paper of medium quality, which is obtained by processing
High-yield pulp or wood pulp has been produced at acidic or neutral pH, or a base paper for coated paper of high quality which has been produced from bleached pulp.

In the method according to the invention, the reduction the water retention of the coating after application to the raw paper as well as disturbances such as streaks, Scratches, stains and paper tears are reduced in a remarkable way. Since the order weight with With the help of lower blade or rod contact pressures than previously possible, it is possible to control the

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Increase the concentration of the coating slip and make high quality coated paper with excellent To maintain paper gloss, smoothness and ink gloss after printing. Also can by increasing the concentration of the coating, the costs for the devices and the drying energy can be reduced.

That obtained with the aid of the method according to the invention Coated paper shows the excellent ones according to the invention achievable properties when it is made with the help of a supercalender, a gloss calender, etc. is post-treated, but can also be used as matt paper, slightly post-treated or non-post-treated paper be used. The coated paper can be printed using any printing process, such as through Offset printing, gravure printing, letterpress printing and flexographic printing with plate or fabric.

The following examples serve to further illustrate the invention.

Examples 1 to 8 and Comparative Examples 4 to 8

A base paper with a basis weight of 55 g / m ² for coated paper is produced as follows: A paper stock is prepared by adding 0.3 parts by weight of resin size and 15 parts by weight of talc filler to a pulp suspension 20 parts by weight of bleached softwood or softwood kraft pulp (hereinafter referred to as "NBKP") and 80 parts by weight of bleached hardwood or hardwood kraft pulp (hereinafter referred to as "LBKP"), the pH of which by means of Alum is set to 4.5. This paper whole

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Fabric is processed into paper with the help of a Foudrinier paper machine, after which the paper produced in this way is size-pressed in such a way that there is an absorption of oxidized denatured starch of 1.5 g / m ² (total amount for both sides).

The coating slips with the properties given in Table I below are each produced by that one consists of the pigments, binders and auxiliaries given in Table I. Mass with 0.2 parts by weight of sodium polyacrylate as a dispersant and 0.3 parts by weight of calcium stearate as Lubricant mixed in a dissolver (Cowles).

15 The coating slips obtained in this way are carried

with the aid of a blade coater of the non-rod type with a short dwell time on both sides of the base paper, with an application weight of 15 g / m ² (per side) and 30 g in Examples 1 to 7 and Comparative Examples 4 to 8 / m ² (for both sides) is used, while in the case of Example 8 an application weight of 8 g / m ² (per side) or 16 g / m ² (for both sides) is used. The coating speed in example 2 is 300 m / min, in examples 1, 3, 5, 6, 7 and 8 and comparative examples 4 to 8 900 m / min and in example 4 1400 m / min. The residence times used in the respective examples and comparative examples are also given in Table I.

The coated paint obtained in this manner according to Examples 1 to 8 and Comparative Examples 4, 6, 7 and 8 Paper is reworked with the help of a supercalender, the processability of each coating slip and the properties of the coated papers before and after

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prints are also given in Table I. It should be noted / that in Comparative Example 5, the Processability of the coating slip was too poor to to form a coated paper. 5

Comparative Examples 1 to 3

The same base paper is made as in the examples 1 to 8 and the comparative examples 4 to 8 and produces coating slips with the in the table below I specified properties using the methods specified in the examples and the comparative examples here.

Each of the coating slips obtained in this way is applied using a blade coater with a flooded nip blade coater with an application weight of 15 g / m ² (per side) and 30 g / m ² (for both sides) Base paper on. Then the coated paper is finished with the help of a supercalender.

The coating speed is 300 m / min in the comparative example and 2 in the comparative examples and 3,900 m / min. The residence times used in each of the comparative examples are also in the table I stated.

The processability of each coating slip and the properties of the coated paper before and after printing are given in Table I. It should be noted that, in Comparative Example 3, the processability of the coating slip was too poor to form a coated paper.
35

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Example 9 and Comparative Example 9

A base paper with a basis weight of 40 g / m ² for coated paper is prepared as follows: A paper stock is prepared by adding 0.2 parts by weight of resin size and 20% by weight of talc as filler to a pulp suspension of 50% by weight. Parts stone-milled pulp (hereinafter referred to as "SGP") and 50 parts by weight NBKP, the paper stock being adjusted to a pH of 4.5 with alum, after which the paper stock is processed into paper with the aid of a Foudrinier paper machine .

Prepared according to the procedure given in Examples 1 to 8 and Comparative Examples 1 to 8 one coating slips with the properties given in Table I.

These coating slips are applied to both sides of the base paper with an application weight of 15 g / m ² (per side) or 30 g / m ² (for both sides) with the aid of a blade coater of the non-stick type with a short dwell time. Then the coated paper is post-treated with the help of a supercalender. 25th

The coating speed is 900 m / min. The residence time is given in Table I. The workability of each coating slip and the properties of the coated paper before and after printing are also given in Table I.

As can be seen from the examples, it is with the help of the process according to the invention for the production of coated Paper possible to take advantage of a coating slip with a high solids concentration. The inven-

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duly used coating slip has excellent theological properties and good processability. The coated paper obtained has satisfactory paper gloss properties and the smoothness and excellent properties after printing such as printing by offset printing or gravure.

TABLE I.

1 2 B. 3 ice cream P i e 1 e 40 I.
8th t
9 4th 5 94 Coating slip 20th 20th j 20 6 7 20th 70 Kaolinanreil (parts by weight) 94 94 I 94 20th 10 60 94 73 Particle content <1 µm (* 1) 94 94 20th Share of ground natural 80 80 80 58 85 80 30th lichen: calcium carbonate 80 90 56 (Parts by weight) 90 90 90 80 90 90 Particle content <2 μΐη (* 1) 68 68 68 90 90 A. 68 68 Particle content <1 µm (* 1) 6S 68 90 10 binder A. A. A. 68 A. A. B. latex 10 10 10 A. A. 3 10 8th Proportion (parts by weight) A ' A. A. 10 12th A. ■ _ A. _ strength 3 ■ 3 3 A. - 10 - 3 _ Proportion (parts by weight) - - 3 - A. 66 _ NaOH Other resources - - - - 3 1200 - pH 9 Proportion (parts by weight) 66 70 70 - _ 0.6 70 66 Concentration (wt .-%) 500 1500 1500 ~, ~ 78 - 1500 4000 Brookfield viscosity (* 2) 0.3 0.55 0.55 1500 4200 70 0.002 0.55 1.5 Viscosity under action 0.55 2.5 1400 15th high shear forces (* 3) 0.002 0.006 0.002 0.65 © 0.002 0.002 Dwell time (s) 15th 15th 15th 0.0014 0.002 71 8th 15th Application weight (per side) g / m ² θ O © 15th 15th 0.002 O O 0 Processability (* 4) 62 66 66 3 0 15th 55 60 73 Gloss of the paper before loading
print (* 5) O O • 66 70 θ - O © Smoothness of paper before loading
print (* 6) 47 54 54 O 0 61 48 - Gloss of the paper after
Printing (* 7) * "■ - 54 56 0 - Suitability for gravure printing (* 8) 50 -

TABLE I (continued)

■ treichcasse

Kaolin content (parts by weight)
Content of particles <1 µm (* 1) proportion of ground natural Calciurccarbcr.at
(Parts by weight)

Salary ar. Particle -el μ.πι 1 * 1) Particle content. ·: 1 ~ m ', * i>

latex

Proportion (parts by weight ¹

Strength

Proportion (parts by weight)

Different tools

Proportion (parts by weight)
concentration lWeight-ΐ)

irockfield viscosity '* * _;

/ iscosity under action
- rather shear forces (* 5)

.'erveiiti-it (s)

V-if tragsaewicht '. Per page) g. · .'erarbeitbarkeit (* 4)

31anz des Papier-rs before the Be-Ir ucker. (* 5)

31 Place of paper ver der. Printing (* 6)

Slan'z of the paper after that
Printing (* 7)
Suitability for gravure printing (* 8)

20 94

80

90 68

10

70 1500

0.55

** ¹ ^ O • J f UO

15 Λ

61

50

Compare this to the game

3 '4 5 y. 6 7

20 94

80

90 68

10

7 C 1500

3.027 15 ο

63 Δ 51

10 94

90

90 68

10

78 = 20C

15 χ

A i

!

^B i

ι

Sodium j

alginate!

0.2 y

:

20th
94

80

90
68

A.
12th

0.002
15th

: 82
! 10000 <

<

0.002
15th
χ

40 42

60

90 68

10 A

70 1800

0.75

0.002 15

59

48

40 94

60

56 27

10

70 2200

0.8 15

43

100

.90

68

A 8 A 5

70

C,

^ ¹ / \ J \ J έ

.15

58

40

90 73

IC

90 68

OK

pH 66

is

75

rn m D.

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Description of the components in the examples and Comparative examples used coating slips

In Examples 1 to 5, 7 and 8 and Comparative Examples 1 to 5 and 7, the product "Amazon 88" (trademark) from Caulim da company is used as kaolin Amazonia Ltda., Brazil.

In example 6, the material is used as the kaolin "HT" (trademark) from Engelhard Minerals & Chemicals Corporation (hereinafter referred to as "EMC"), USA.

In that used in Example 9 and Comparative Example 9 Kaolin is the product "Ultra White 90" (trademark) from EMC, USA.

In the comparative example 6, kaolin is used the product "Klondyke" (trademark) from EMC, USA.

In Examples 1 to 6, 8 and 9 and Comparative Examples 1 to 6, 8 and 9, ground is used natural calcium carbonate the product "Carbital 90" (trademark) from Fuji Kaolin Co., Ltd., Japan,

In example 7, the product "Softon 1800" (trademark) is used as the ground natural calcium carbonate from Bihoku Funka Co., Ltd., Japan, which is obtained with the aid of a sodium polyacrylate dispersant, which is slurried in an amount corresponding to 0.4% by weight of the ground natural calcium carbonate, after which the slurry is prepared using a sand mill (trademark "Perl Mill") from Draisworke GmbH, Federal Republic of Germany.

In the comparative example 7 is used as a ground

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nes natural calcium carbonate the material "Softon" 1800 "(trademark) of Bihoku Funka Co., Ltd., Japan.

That in Examples 1 to 8 and the Comparative Examples 1 to 8 latex used Λ is a styrene / butadiene polymer latex, sold under the trademark "SN307" by Sumitomo Naugatuch Co., LLd., Japan will.

In that used in Example 9 and Comparative Example 9 Latex B is an alkali-sensitive one Styrene / butadiene / butyl acrylate / methyl methacrylate copolymer latex, that sold under the trademark "L-1953" by Asahi Chemical Industry Co., Ltd., Japan will.

The one used in Examples 1 to 4 and 6 to 8 and Comparative Examples 1 to 3 and 6 to 8 Starch A soluble in cold water is the product "Hi-coastar PC 11" (trademark) from Sanwa Cornstarch Co., Ltd., Japan.

The oxidized one used in Comparative Example 4 denatured starch B is the product "Ace A" (trademark) from Uji Cornstarch Co., Ltd., Japan.

Footnotes to Table 1 f

* 1) Particle size distribution: The numerical values give the Particle size distribution as a weight percentage which has been determined with the help of a particle size distribution measuring device ("Sedigraph 5000-01" (Trademark) of Shimad / .u Corp., Japan. * 2) Brookfield Viscosity: The Applicable Numbers

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stand for the viscosity in centipoise (cP) obtained with the aid of spindle no. 1 at 60 min operated Brookfield viscometer has been measured are.

* 3) Viscosity under the action of high shear forces: The numerical values indicate the viscosity in centipoise (cP), which with the help of a high shear visco

simeters (Hercules from Kumagai Riki Kogyo

Co., Ltd., Japan) at Bob E, 8Q00 min, d. H. egg-

4 -1

A shear rate of 8.4 10 s is measured have been.

* 4) Workability: The workability becomes visual about defects such as streaks, scratches and stalactites as well as about the evenness of the painted Surfaces, rated :. The evaluations are carried out using the following relative evaluation standard:

(good) (υ) Q ZY x (bad) * 5) Gloss of the paper before printing: The numerical values indicate the gloss in percent, which was ^{measured at 75 ° / 75 ° with the CLnC 1} S gloss meter.

* 6) Smoothness of the paper before printing: The smoothness 25 is visually evaluated, with the evaluations with With the help of the following relative evaluation standard are given:

(good) (S) O Δ x (bad) * 7) Gloss of the paper after printing: The coated paper is coated with 0.3 cm ^{3 of} black printing ink using a printing tester (RI Printing Tester from Akira Industry Co., Japan ) printed. The gloss of the printed paper is then determined in the manner described above under * 5).

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The measurement results given indicate the percentage of gloss.
* 8) Suitability for gravure printing: The coated paper is printed with the help of a gravure printer from the company. Kumagai Riki Kogyo Co., Ltd., Japan. Then the reproduction of the points is assessed visually using the following standard of assessment:

(good) (o) O ^ ^x (bad) Example 10 and Comparative Example 10

A base paper with a basis weight of 55 g / m ² for coated paper is prepared as follows: A paper stock is prepared by adding 0.3 parts by weight of resin size and 15 parts by weight of talc as filler to a pulp suspension of 20% by weight. Parts NBKP and 80 parts by weight LBKP, this paper stock adjusted to a pH of 4.5 with the help of alum and processed into paper with the help of a foudrinier paper machine, after which the paper produced in this way with the application of oxidized denatured Starch with an application weight of 1.5 g / m "* (total amount for both sides) is treated in a size press.

Then, with the aid of a dissolving device (Cowles dissolver), coating slips are made from the following Ingredients with those specified in the TabeJlo Jl Concentrations made:

30 '* 40 parts by weight kaolin ("Ultra White 90" (trademark) from EMC, USA)

(Proportion of particles with a particle size below 1 µm: 73% by weight)
* 60 parts by weight of ground natural calcium carbonate ("Carbital 90" (trademark) from Fuji Kaolin)

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Co., Ltd., Japan).

(Particles with a particle size below 2 μΐη:
90 wt .- 'ε, particles with. a particle size below 1 µm: 68% by weight)

* 10 parts by weight of styrene / butadieri copolymer latex ("SN307" (Trademark) of Sumitomo Naugatuch Co., Ltd. Japan)

* 5 parts by weight of oxidized denatured starch ("Ace A" (trademark) by Oji Cornstarch Co., Ltd.,

10 Japan)

* 0.3 part by weight of sodium polyacrylic aL.

The coating slips obtained in this way are, with With the help of a stick-type blade coater

applied to both sides of the base paper, the residence time varying in the manner indicated in Table II is done by adjusting the speed of the brushing in the direction and the distance between the application mechanism and dom SLab Mechanism varies. The cancellation conditions and processability are also given in Table II.

The coated paper obtained in this way is post-treated with the aid of a supercalender. The egg-

Properties of the finished paper before and after printing are also given in Table II. As can be seen from Table II, the processability of the coating slip used in accordance with the invention is particular
excellent. Therefore, the concentration of the coating slip can be increased and a coated paper having excellent properties can be obtained. In Comparative Example 10, in which a longer dwell time is used, the processability is poor, that is, it is impossible to obtain a coated paper

obtained when the concentration of the coating is 60 S or more.

TER MEER · MÜLLER · STEINKEI5TER

^: Kanzak.i · Paper ... F-273

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TABLE II

10 15 20

Example 10 60 60 70 i / I get an example of the game 10 70 Concentration of 60 Coating slip 55 840 840 1700 55 1700 (Wt .-%) Brookfield Visco 840 sity of the prank 600 6 00 mass (cP) Blade prank 0.003 0.0016 0.003 0.04 direction of the rod typs 600 1200 600 0.04 600 - dwell time (s) 0.003 0.04 -Speed speed 9 11 14 600 18th speed (m / min) 600 600 -Order weight Θ (ο) O 12th χ (per page) 7th 9 (g / m ² ) 56 58 64 χ - -Processable
ability (* 1) © Δ Gloss of the paper - before printing 50 O 51 - (* 2) Smoothness of the pa - piers in front of the Be O 43 44 48 Δ - print (* 3) Gloss of the paper - after printing 41 4.1 (* 4)

25 Comments on Table II:

* 1) Workability: The workability becomes visual rated on defects such as streaks and stains and on the evenness of the painted surfaces. The evaluation is made using the following

relative evaluation standard:

(good) (o) Q Δ χ (bad)

35

* 2) Gloss of the paper before printing: The numerical values indicate the gloss as a percentage that is at 75 ° / 75 ° with the aid of a gloss meter.

00ZÖUD4 TrR MEER ■ Müller · ^ TElNtVrElSTE-F *. . . Käniäkl Paper ... P-273

* 3) Smoothness of the paper before printing: The smoothness of the paper is visually assessed using the following assessed according to the specified relative assessment standard:

⁵ (good) (o) OA χ (bad)

* 4) Gloss of the paper after printing: The coated paper is coated with 0.3 cm ^{3 of} black printing ink using a printing test device (RI Prin-

ting tester from Akira Industry Co., Japan) printed, after which the gloss of the printed paper is rated in the same way as specified under * 2) · The results of this evaluation are also expressed as a percentage.

Examples 11 to 13 and Comparative Examples 11 to 13

By mixing the in the following Table III specified pigments with 10 parts by weight of a styrene /

20 butadiene copolymer latex ("SN307" (trademark) of

Sumitomo Naugatuch Co./ Ltd. Japan), 5 parts by weight of cold water-soluble starch ("Hi-coastar PC-11" (Trademark) of Sanwa Cornstarch Co., Ltd., Japan) and 0.3 parts by weight of sodium polyacrylate in a

25 ner dissolving device (Cowles dissolver) is prepared

Coating slips with the in the following table III specified properties.

Each of these strokes is applied to both sides of the in Example 10 described base paper applied, and /.was in the examples 11 to 13 and the comparative examples 11 and 12 by means of a stick type blade coater with a short dwell time and in Comparative Example 13, using a conventional non-stick type blade coater with a

TER MEER · MÜLLER · STEINN / JEI5TE-.F2 ":

K, "ui; '.,' Ik i Paper

F-27

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short dwell time, the coating speed being 900 m / min and the application weight being 12 g / m ² (per side) or 24 g / m ² (for both sides). The processability and the properties of the coated paper before and after printing and also given in Table III.

TABLE III.

Coating slip

Content of kaolin (parts by weight) Content of particles 1 µm (* 5) Share of ground natural calcium carbonate (parts by weight)

Content of particles below 2 µm (* 5)

Content of particles below 1 µm (* 5)

Concentration of the coating slip (% by weight)

Brookfield viscosity of the coating slip (cP)

Coater dwell time (s) workability (* 1)

Gloss of the paper before printing (* 2)

Paper smoothness before printing (* 3)

Gloss of the paper ^ _n . after printing ^Jb (* 4)

Examples

11th

40 73

60

85 56

65 750

540

0.002 0.002 0.002

Co) 6

(O)

(o) (ο) ο

1 1 Comparison
examples
12 13 90 90 _ 58 58 - 10 10 100 56 56 90 27 27 68 65 6 5 68 1400 1400 450 0.002 0.002 0.002 X X Θ ; _ 4 4

4th

TER SEA · MCH LER ■ STEIINlOfFlCiTFJ-? - - ^: - "-K.änv ^ ky. Paper ._.. * ..." .. * ...- ".-!» _ '. L * r_ »« i «

As can be seen from dor obiycn Table 11, allows the inventive method remarkable improvements in processability and properties of the obtained coated paper. In Comparative Examples 11 and 13, the processability is increased bad for obtaining a coated paper. In the comparative example x 12 shows the obtained painted Paper has very poor properties. The in Examples 11 to 13 and Comparative Examples 11 to 13 pigments used are the following:

* The one used in Examples 11 and 13 Kaolin is the product "Ultra White 90" (trademark) from EMC, USA.

* The kaolin used in Example 12 and Comparative Examples 11 and 13 is the Product "HT" (trademark) from EMC, USA.

* The ground natural calcium carbonate used in Example 11 is prepared by the company's product "Softon 1800" (Trademark) Bihoku Funka Co., Ltd., Japan using of 0.4% by weight (based on the ground natural calcium carbonate) sodium polyacrylate as a dispersant slurries and the slurry with

25 The aid of a sand mill (trademark "Perl Mill"

of the company Draiswerke GmbH, Federal Republic of Germany) married.

* In that in Examples 12 and 13 and the comparative example 12 used ground natural

30 chen calcium carbonate is the product "Carbital 90" (trademark) from Fuji Kaolin Co., Ltd., Japan.

* The one used in comparative examples 11 and 13 ground natural calcium carbonate

35 is the product "Softon 1800" (Wa-

TER MEER MÜLLER STEINrv: iEI3TKM _ Ka ^ d-ki Paper ... F 273

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Rename) from Bihoku Kunku Co., McI.

With regard to footnoles (* 1) to (* 4) of Table III
see footnotes (* 1) to (* 4) of Table II.
5

Footnote * 5): Particle size distribution: The numerical values indicate the particle size distribution as a percentage Again, the iniL aid of a particle size distribution measuring device "Sedigraph 5000-01 "(Trademark) of the company

Shimadzu Corp., Japan.

Claims (3)

PATENTANWÄLTE - EUROPEAN PATENT ATTORNEYS Dipl.-Chem. Dr. N, ter Meer Dipjl -Intj H. Stoinmeister Dipl.-Ing, F. E. Müller Λ. . . . , ". Triftstrasse 4, Artur-Ladebock-Strasse D-8OOO MUNICH 22 D-4UOO UILLEf-ELD 1 tM / cb August 03, 198 3 Case F-273 KANZAKI PAPER MANUFACTURING CO., LTD. 9-8, Ginza 4-chome Chuo-ku, Tokyo, Japan Method of Making Coated Paper Priority: August 12, 1982, Japan, No. Sho 57-140807. Sep. 3, 1982, Japan, Claims No. Sho 57-154161 1. Process for the manufacture of coated paper 5 by coating a base paper with a coating slip containing pigments and one or more binders, characterized in that (a) the coating slip has a solids concentration of 40 to 80% by weight and as pigments, each based on the total pigment content, up to 80% by weight kaolin and 20 to 90% by weight of ground natural calcium carbonate TER MEER MÜLLER STEINMEIS1; ER. I * t contains, wherein the kaolin has a content of particles with a particle size below 1 μ, πι of more than 50 wt .-% and the ground natural calcium carbonate has a content of particles with a Particle size below 2 μm from 70 to 100% by weight and of particles having a particle size below 1 μm from 55 to 95% by weight, and (b) a time interval of 0.0005 to 0.015 seconds between the time an excess is applied Amount of coating slip on the base paper and the time of stripping off the excess Coating mass is adhered to. 2. The method according to claim 1, characterized in that that the coating slip with a solids concentration of 6 3 to 80 wt .-% with Is applied to the base paper by means of a blade coater of the non-rod type. 3. The method according to claim 1, characterized in that the coating mass with a Solids concentration of 4 5 to 70 wt .-% with Is applied to the base paper by means of a stick type blade coater.