DE1546391A1 - Process for coating paper and means suitable therefor - Google Patents

Description

DR.ING. F. WUESTIIOFF. 8 MUNICH SCHWEIQEHSTRASSE DH.E.V.PECHMANN »« »» »22 06 DB. ING. D. BEHRENS tblkobammaduessK! PATENTANWÄLTE pkotkctpatbnt "ϋκοπκκ

1A-28 July 15, 1969

Honor exercise to the patent application

ASTHUED. LITIELE, INC., Cambridge 40, Massachusetts, UvS.A

concerning

"Process for the coating of paper and suitable therefor

Middle"

Me invention relates to a method for painting Papers and agents suitable therefor, in particular for the production of art print paper using a Coating slip in the form of an oil-in-water emulsion, where the continuous phase a film-forming binder, such as a protein product or an elastomer as well as a contains fine filler, and the disperse fiber is an organic liquid boiling over water.

It is already

Documents (Art. 7, Paragraph I, Paragraph 2, No. 1, Clause 3 of the Amendment Act of 4.9.1967J

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a coating slip for high gloss and good transparency of the papers has been proposed. This is achieved by that on the base paper a coating is applied with the help of an emulsion, which becomes a cellular Porosity leads. Serve as the base of this emulsion here proteins and / or elastomers. Large-scale cardboard manufacture has particular advantages.

Up to now it was used for coating e.g. art paper a coating slip in the form of an aqueous slurry of clay and starch or casein. For example, 3. for a

unsized base paper - about 40 to 43 g / m - the order Coating mass (calculated on dry weight) approx. 17.5 g / m 2. Thus, paper leas with a weight of approx. 5 7.5 to are obtained

2
60.0 g / m. Are the papers coated on both sides?

2, each with an application weight of about 8.8 g / m, see above

3 2

an application volume of about 4.8 cm / m is possible, corresponding to a layer thickness of about 3.8, and the like.

For printed matter such as magazines and magazines, The weight of the paper is of particular importance, especially with regard to the total cost of these printed products. In view of this, however, it is generally not possible to determine the weight of the base papers or the coating decrease, because this measure has because of the decreasing strength of the papers, the opacity of the coated Papers and the deterioration in printability and behavior in printing soon reaches its limit. As is well known, the running behavior is also that Plucking the paper on the printing units% of particular importance when using the machines. This is especially true

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in rotary printing or similar works that print on endless paper webs at high speed. If you set the weight for; the line in the well-known clay and starch or clay and casein containing spreads the printability deteriorates Printing smoothness and ink absorption. This cannot be counteracted by using materials with a higher gloss or Opacity applies, so that theoretically a smaller order volume and thus a smaller layer thickness of the line would be achieved. In this case, other difficulties arise on the printing machines. It is obviously a minimum line thickness is required, otherwise there will be irregularities and irregularities Printing smoothness to different ink absorption behavior. "

Various coating slips can be used excellently for cardboard coating, but these are great for print products, such as for printing magazines or magazines. not applicable. These known or suggested Coating slips for cardboard list> at the time of transfer the coating of paper for printed matter at working conditions that are in the context of a modern Can not realize printing press with fast running paper web without significant disadvantage. These Difficulties are generally based on the rheological or flow properties of the coating slip or the for the Drying of the coated papers required time or temperature. Coating on paper machines is generally done with the help of doctor blades or rollers

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Paper speeds of the order of 760 m / min.

With this coating process, extremely high shear forces occur on the papers. The coating must flow instantly and distribute evenly, so that the coated paper does not have any stripes or musterartigaa Has irregularities in the stroke. An uneven stroke is very detrimental all print products. So it will depend on the properties of the coating whether it is flawless can apply at high paper speeds. In particular, it concerns the flow behavior within the coating process Temperature range and the change in viscosity behavior with the temperature under the prevailing shear forces, in other words, the dependence the viscosity, the temperature and the shear stress.

Another prerequisite for machine coating is that the coating does not contain large amounts of water, which is true must then be removed again. Coating slips are therefore preferred with the highest possible concentration, that is to say with the maximum possible solids content. The one for cardboard Although suitable coating slip has a very high solids content, it is suitable for machine coating not suitable. It is an emulsion containing a highly volatile organic solvent, like kerosene, -which compared to aqueous slurries of clay with casein or starch has advantages because of the volatility of the organic component.

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When coating base papers, it is also important to ensure that that the ink uptake or the drying of the printing ink is to be set precisely. "The color shot and the drying of the printing ink also significantly influence the printing process and the achievable Print speed. In addition to the properties of the coated papers, in terms of ink absorption and drying the printing ink is also the whiteness, the gloss and the evenness of influence. There is a certain Relationship between pressure absorption and drying speed on the one hand, and the gloss and evenness of the print on the other. If not satisfactory Ink absorption or drying speed results in matt and unsightly printed products Ink receptivity leads to shiny, sharp prints. Ultimately, excessive ink uptake or insufficient drying of the ink leads to one '. Smearing and a lack of adhesion between the dried-on printing ink and the paper coating. It is desirable that the ink not run too quickly is believed, however, a part of it adheres to the paper surface and results in rich prints. .

As mentioned earlier, it is desirable to be deleted Produce papers with the lowest possible weight. It has also already been pointed out that easily printable Papers don't just reduce the thickness of the line or the applied volume can be obtained. However, there is a certain strength of the line necessary to avoid any bumps and irregularities

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to balance the raw papers and the necessary Ensure print smoothness. There must also be a certain resilience of the papers when painting, which occurs during the printing process is essential to be preserved. In the case of a new coating material, it should also be ensured that the coated Papers with regard to picking on the printing unit are at least as good as the known coated ones Papers.

The invention now relates to a method of painting of papers using a coating slip in the form of an oil-in-water emulsion, which is based on high-speed Paper making machines is applicable and results in coated papers that work at high paper speeds excellent on all types of printing. They are characterized by particularly favorable behavior with regard to Ink absorption, drying speed of the printing ink and plucking out. The method according to the invention for coating paper using a coating slip in the form an oil-in-water emulsion, the continuous .Phase a film-forming binder, such as a protein or dispersed an elastomer and a fine filler contains and the disperse fiber is an organic liquid boiling over water, is now characterized by that an oil-in-water emulsion with a droplet,

and size from 0.6 to 1.5 »u uses the continuous Phase additionally contains gelatinized starch * The production the oil-in-water emulsion used according to the invention is done by dispersing protein or Elastomer in water, emulsify the organic liquid in this dispersion and finally add the filler

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substance and the gelatinized starch in this pre-emulsion. The ratio of binder to starch should be 1.1 to 1.5. The filler can be clay and the ratio of binder + starch to filler can be 1: 0.5 to 1: 4. The ratio of binder + starch to the disperse phase can be between 1: 1 and 1:10. The solids content of the coating should be at least 20 % . It turned out to be useful to paint at an elevated temperature.

The rheological application of the oil-in-water emulsion used according to the invention is particularly useful for coating on high-speed paper machines. The coated papers show excellent properties on high-speed printing units. The stable viscosity-temperature behavior of the oil-in-water emulsion used under the shear force that occurs during painting is remarkable. Due to the high stability of its viscosity-temperature behavior, the coating slip according to the invention is not very sensitive to minor changes in the process conditions during the coating process. The line obtained is particularly evenness and smoothness. The application weight is surprisingly low, so that plain coated papers can be given a significantly lower weight than is the case with conventional coated papers. The solids content of the coating slip is so high that the liquid content to be removed on the paper machine is low and can be removed at a sufficient rate without adversely affecting the paper machine itself.

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In the case of the coating slip used according to the invention, the starch has a viscosity-stabilizing effect. As mentioned several times above, the known coating slips contain, in addition to the white pigment, such as clay, either Casein or starch. It was previously of the opinion that spreads containing both proteins as

VLHj

starch paste / are also useful. Even the attempts with such coating slips in an alkaline environment was unsuccessful because the casein makes it water-resistant and the binder like strength very much Little or no improvement could be made. It was also found that with a small amount of Starch paste in a casein-containing spread even a reduction in bond strength was found. (S. Casey, "Pulp and Paper", Vol. III, p. 1595 (1961).) Further difficulties arose with regard to the homogeneity of the emulsion when starch and casein were added. Both substances were often precipitated.

It was therefore impossible to foresee that it would be possible at all to contain usable coating slips in addition to the white pigment make both casein and starch paste. What is particularly surprising is the fact that through Combination of casein and starch paste in the inventive Coating mass the rheological or flow properties could be stabilized so that the mass also in the context of paper machines, i.e. at high paper speeds, can be used properly. In previous attempts with coating slips, containing Casein and starch, the strength didn't even match. the addition of the strength of the individual components. It showed.

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found that under these conditions the strength did not increase the strength of the casein bond, but merely increased it acted as an inert material (see Sutermeister and Browno, "Casein and Its Industrial Application", p. 294 (1939)) In the case of the coating slip used according to the invention, there is a synergistic effect of the starch with the casein observed. The starch is completely compatible with the casein in the coating and makes a significant contribution to the stability of the viscosity. It does not lead to deterioration the pick resistance, the opacity and the gloss of the coated 'papers compared to the papers coated in a known manner.

The method according to the invention should be based on the figures further explained. .

Fig. 1 shows a flow sheet of the inventive method for painting Paper.

FIGS. 2 to 4 schematically show a section of the papers coated according to the invention.

5 shows the dependency in a diagram the viscosity (according to Brookfield)

from
depending on the temperature.

6 shows the dependency in a diagram the shear force from the torque in an apparatus for determining viscosity for the

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coating slip according to the invention and coating slip containing only casein the state of the art. "";

FIG. 7 shows, in a diagram similar to FIG. 5, the dependence of the viscosity on the temperature for coating slip according to the invention and known coating slip the base of casein.

The coating slip according to the invention is an oil-in-water emulsion, protein as a binder and starch being present in the aqueous phase. In this emulsion is the disperse phase is an organic medium which is immiscible with water and whose boiling point is higher than that of water lies. The particle size of the disperse phase should be about 0.5 to 1.5. Finally lies in The continuous phase of the emulsion is preceded by a fine filler, which the coated papers the to give desired surface properties.

In the manufacture of those used according to the invention In the coating slip, the binder is first introduced into the water and then mixed in with the organic substance a pre-emulsion is formed. This then becomes starch paste and then the pigment or filler mixed in. Customary emulsifiers can optionally be used use. The emulsion should have a solids content of preferably at least 20%.

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When drying the coating slip according to the invention on the In the paper web, the disperse phase remains in a gelled matrix. The rest of the Water and the organic liquid removed, so that starch and binder particles are in the line has a uniform distribution. The shift is porous. So there are interfaces between air and binder, wherein the pore size corresponds to the size of the disperse phase, in other words on the order of 0.5 to 1.5, u.

As already mentioned, the starch in the coating slip according to the invention stabilizes the viscosity in the temperature range from about 32 to 49 C.

The flow diagram of FIG. 1 shows the production of the coating slip according to the invention and its use for. the machine coating of paper. The coating slip according to the invention is produced in such a way that casein is first dispersed or dissolved in water. The emulsifier and the water-immiscible organic liquid are then introduced into the aqueous casein solution and emulsified to the desired degree of fineness. Starch paste and the pigment, i.e. a finely divided material, are introduced into this pre-emulsion. In this case, casein was used as a film-forming binder. In principle, one can use as a binder substances which lead to a removal of a portion of the water to a gel-like mass. It forms an uninterrupted layer of this binding agent with pores which have interfaces between binding agent and air. It is suitable with other words

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For this purpose, casein, i.e. proteins, water-dispersible elastomers, such as natural and synthetic types of rubber. Proteins such as casein and ¥ protein are preferred. Depending on the binder used, it will be possible to obtain a solution or a dispersion with water, as well as all intermediate stages via spurious solutions. An initial solution of a protein material can be excreted in a finely dispersed manner by adding electrolytes such as alkalis. If necessary, solubilizers can also be used. Since, as is known, products containing casein do not have any particular water resistance, a substance is required for the coating which brings the casein or other protein within the finished coating into an essentially water-insoluble form. In general, this is done by adding to the solution or dispersion of the protein product an inorganic metal salt which is sufficiently soluble in water and which is able to form insoluble compounds with the binder, for example zinc sulfate. A water-insoluble zinc salt of casein then evidently forms in the finished coating slip, as a result of which the water resistance of these coated papers is improved. Other metal ions such as copper * aluminum or chromium can also be used for this purpose. However, these measures are known. A water-immiscible organic liquid with a boiling point above that of water serves as the disperse phase of the emulsion; However, in order to be able to drive off the organic substance during the drying process, its boiling point should not be above about 260 ° C. The vapor pressure of the organic substance in the temperature range of the predrying and thus the gelling of the binder should also be below that of the water, see above

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that part of the water can be removed without having already done so expelled a larger amount of organic liquid will. As a disperse phase in the inventive Coating agents are e.g. xylene, kerosene, lacquer petrol, distillates with a high flash point, ketones such as Bu.tyl methyl ketone or amyl ethyl ketone, paraffin hydrocarbons such as octane and higher-boiling acetates such as butyl acetate or amyl acetate.

When choosing the organic substance, it is also important to ensure that the paint has an optimal gloss Paper is to be preserved. This .must go with the other components of the mass, such as the binder, emulsifier or any additives such as colorants, be compatible. The other properties must also such as toxicity, flammability, adaptability to the manufacturing process, price and the like.

As an emulsifier or dispersant, one can use customary for the production of the coating slip according to the invention surface-active substances such as oleate or stearate from Use ammonium, sodium or potassium. It can also Form in situ from an existing weak organic acid and alkali ions, if such as solubilizers e.g. by adding stearic acid to ammonium-containing water. ·

The weight ratio of binder + starch to the disperse phase should be between about 1: 1 and "1; 10. In general, the gloss of the coated papers, the greater the lower the proportion of binder. A ratio of about 1: is preferred. 5. The "

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Binder - solution or> * dispersion should have a solids content of about 5 to 40% . ' . The proportion of emulsifier can be between 2 and 5% by weight, based on "the disperse phase. In general, higher solids concentrations are preferred.

As a starch, one can use the usual starches, such as those used in the paper processing industry. It can be an oxidized starch, an enzymatically digested starch, a so-called aidehyde starch or a starch that has been hydrolyzed to a low molecular weight. (TAPPI Monograph Series No. 17 , "Starch and Starch Products in Paper Coating" (1957)) To produce the starch paste, starch is boiled for about 10 to 15 minutes at about 88 ° C., and an approximately 20 to 35% strength starch paste is then used the solution or dispersion containing the binder at a temperature of about 71 to 76 ° C was added. The ratio of binder (casein) to starch can vary between about 1: 1 and 1: 5. In general, it can be said that the lower the starch content, some difficulties arise in stabilizing the viscosity at a higher temperature. Excessive amounts of starch again make it more difficult to form an even coat.

Finally, a fine pigment is added to the mass, which enhances the surface properties of the coated paper, especially d'ie printability and the pick resistance, improved. One uses for this in the general finely divided inorganic substances which are inert to the substances present in the system. The grain size is preferably below 12 λι. The inventive

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According to the applicable filler does not always have to be a pigment to improve the opacity of the papers. Except for one improvement the opacity and gloss of the coated papers, they improve color pick-up and sometimes lead to a change in the superficial appearance of the coated papers. One can by bringing in of e.g. powder or flakes of aluminum can achieve a metallic appearance.

As fillers in the coating slips according to the invention e.g. chalk, clay, titanium dioxide, hydrous cölcium silicate, metal powder such as aluminum or bronze, Carbon black, color pigments such as ultramarine blue.

The proportion of filler in the coating slip according to the invention can be up to 2 or 3 times the weight of the binder including strength. In terms of printability, there is a binder + starch ratio to the filler between about 1: 0.5 and 1: 4 is preferred.

In the production of the coating agent according to the invention it is advisable to make the binder solution first or dispersion, optionally with a precipitating agent, and then very quickly stirs the disperse phase into this forming organic substance. Should be a dispersant form in situ, the acid is expediently added to the organic substance and the alkaline substance Reactants to the aqueous phase. Often it is then necessary to prepare special emulsification measures.

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increase in order to achieve the desired fineness of the emulsion. This can be done by the usual homogenization. Since the fineness of the emulsion of the disperse phase ultimately influences the extent of the porosity and thus the boundaries between the binder and air in the coated papers, an emulsion fineness of about 0.5 to 1.5, u, in particular not more than 5, is a maximum ^: , expedient. \

The pre-emulsion obtained is kept at about 48 to 54 ° C., and then the hot aqueous starch solution is introduced. The filler is then added. Even so, the fillers are also included in the product of the disperse phase can introduce, it is preferred to stir this into the aqueous phase, because this in general is more viscous than the disperse phase and thus the filler can be dispersed more easily. One also achieves thereby better binding of the filler in the paper.

The coating slip according to the invention produced in this way can can then be applied in the usual way. It is not necessary to completely cover the paper before coating is dry. Coating can therefore be carried out using papermaking perform on one machine. The line> is generally made at a temperature between about 32 and about 38 ° C for high-speed coating machines. Basically you can delete between about 24 and 66 C, as long as the temperature is kept relatively constant.

FIGS. 2 to 4 now show the structure of the line '-, 17 -

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a paper. According to FIGS. 2 to 4, the coating 11a to 11c is on the paper 10, consisting of a continuous phase 12 containing starch and casein. The filler 14 and the particles 13 of the disperse phase are embedded in this. Once the surface has been applied, it is heated in order to first remove part of the water from the continuous phase. There is a binder matrix 15, in which the strength of a gel is present forms (Fig. 3) _e is further heated, the film loses lic (Fig. 4) the remaining water 'and the disperse Phase.Bei start of drying to water and the organic Liquids have different evaporation rates ^ so that very small interfaces between air and binder, i.e. pore walls, are formed _? As can be seen from FIG. 3, the structure of the emulsion is initially still retained in the gel-like base material 15, but the continuous phase can possibly shrink. Only by removing the remaining water and the organic liquid do pores arise in the layer lic, so that the pore walls 17 are found in the mass of the layer 16, which in a special way made the coated papers opaque. "In" the process according to the invention, the dispersion is essentially retained, the pores correspond to the organic liquid and are essentially of the same size. -

t ,

In summary, it can be said that the inventive Paper coating on fast-running paper machines can be done, with the papers to a weight saving

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of approx. 20 % leads (namely from approx. 58 g / cm to approx. 46 to

ρ ■
47 g / cm), but this does not mean a reduction in the

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Order volume is connected. They are also deleted To describe papers as running well on high-quality printing values.

Comparison 1;

About 91 kg of casein were stirred into about 363 l of water and heated to about 66 ° C., then about 16 kg of ammonium hydroxide (28%) were added and a further 10 min until Solution of the casein kept at about 66 ° C. About 8 kg of zinc sulfate heptahydrate were placed in another vessel dissolved in about 68 1 V / water and added to the casein solution about 66 ° C and the mixture at this temperature still about 16 kg of ammonium hydroxide and about 10 kg of oleic acid and then about 148 kg of a kerosene fraction (refined oil No. 9, boiling range approx. 168 to 268 C), up to an emulsion fineness of approx. 0.5 to 1.5 / rev. Now a slurry of 240 kg clay (No. 1) in about 170 l of water with about 0.68 kg of sodium hexameta phosphate (clay dispersant) stirred into the emulsion, Solids content 30%.

example 1

About 45.5 kg of casein were contained in about 205 liters of water about 8 kg of ammonium hydroxide (28%) at about 66 ° C in 10 min and a solution of about 4.5 kg of zinc sulfate heptahydrate added in about 45 l of water. Now about 16 kg of ammonium hydroxide, about 10 kg of oleic acid were added and approx. 158 kg kerosene stirred in (emulsion fineness 0.5 - 1.5, u),

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About 45 kg of oxidized starch in about 182 liters of water were made

Heated for 15 min to about 88 to 90 ° C and then into the Emulsion introduced. Eventually, about 238 kg of clay (# 1) Slurried in about 170 liters of water with about 0.68 kg of sodium heptametaphosphate added and mixed thoroughly to distribute the clay.

The spread contained a ratio of casein and starch 1: 1. It was found that the starch with the casein was present as a continuous film and not as a granular product, like the sound.

The fact that the strength when painting at high speed acts as a viscosity stabilizer, comes from a comparison of the rheological properties of these Coating slip with the comparative product.

The viscosity (according to Brookfield) was at four temperatures measured, with two different speeds being used for the two coating slips.

Tabel'!

comparison CP
100 Rpm Viscosity index Temp. C viscosity
ΊΟ rpm 30th 8OO 1.78 21 54 800 11 600 1.48 30.5 17 200 - 6 200 1.55 40.5 9 600 5 250 1.52 46.5. 8,000

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The viscosity index is the ratio of the viscosity values at the two rotational speeds.

Table 2 "'

according to CP Viscosity index viscosity 100 rpm , 2.91 Temp. ⁰ C 10 rpm 15 200 2.62 21 44,000 10 100 2.60 32 26 400 7 400 2.54 40 19 200 7 200 43 18 400

In FIG. 5, viscosity values at 100 rpm are plotted against the temperature. From the tables and Fig. 5 shows clearly the stabilizing effect of starch. The viscosity of the comparison mass drops with an increase in temperature by about 22 ° C from 30,800 to 5,250 cP, that is by a factor of about 6; according to the invention, however, only from 15,200 to 7,200 cP, i.e. by a factor of a little over These data thus show "that changes in temperature are a little influence on the material according to the invention, however have a clearer influence on the comparison material. The / fact is of great importance in Brushing at high speed.

The effect on temperature dependence is just as important the viscosity belts increasing shear forces, which the viscosity index shows. By increasing the

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velocities in the Brookfield viscometer the thrust forces are increased from 10 to 100 rpm. The mean viscosity index for the reference composition was 1.56 and for that according to the invention at 2.67, i.e. that the viscosity of the V. comparable product is reduced to a much smaller extent. For coating machines for high speeds is this reduction in the viscosity value by shear forces is necessary in order for the coating agent to achieve the desired Shows flow behavior without causing streaky coatings comes. When the shear stress is removed, the viscosity should rise again to allow the coating to rise quickly hardens and remains smooth. As a result, the big difference the viscosities under different shear loads

\ the coating mass according to the invention, in particular between 32 to 49 ° C., the mass according to the invention can be processed in coating machines at high speed, but not a mass such as is used for cardboard materials at low coating speeds and when applied with the aid of an air nozzle. -

To find out the difference in rheological properties between To illustrate the inventive and the comparative product *, the rheogram is shown in one in FIG Diagram showing the torque versus the shear rate is applied (Hercules viscometer for high shear forces). Such a rheogram should show the effect of a Show magnification of shear force and torque. Obviously the flow resistance of a mass is so greater, the stronger this effect is. With increasing flow resistance, it is difficult to achieve a smooth, level. and coating free from irregularities.

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aim. From Fig. 6 it can be seen that with the wet according to the invention only a very small increase in torque or the flow resistance occurs when the shear rate is increased. In contrast, this shows Comparative material shows a significant increase in the flow resistance and clear signs of a! 'Chatter' at high shear rates; this is an indication of instability in the system.

The coating slips discussed were based on base papers

2
40 g / m (RDS laboratory coating rod). A common clay-starch coating was used for a further comparison.

Tabel

weight
each side
g / m ² volume
3, 2
cm / m Layer thickness
/ ^U Tone strength 7.5 3.22 3.2 according to 3.0 3.33 3.3 -

From Table 3 it can be seen that with the erfindungsge would not even require half the application weight for approximately the same application volume for the same thickness. With the same printability, this leads to a considerable saving in weight of the art paper.

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V erq -.1. calibrate 2%

A second comparative product was prepared in which about 45 kg of casein were dispersed in about 205 liters of water and heated to about 66 ° C, then 7.7 kg of ammonium hydroxide (28%) was added, about 10 minutes to about 66 ° C held, a solution of about 4.5 kg of zinc sulfate heptahydrate in about 23 liters of water was added and then about 4.1 ammonium hydroxide and about 2.7 kg of oleic acid were added; finally about 60 kg of mineral spirits (boiling range 171 to 206 ° C) were introduced . The casein ranged in size from 0.5 to 1.5, u. A clay slurry was then added to this emulsion, for the preparation of which about 45 kg of clay (No. 1) and about 22.5 l of water and about 0.225 kg of sodium hexamethosphate were used, the solids content of the emulsion was 23 %. .

Example 2

Comparative composition 2 was modified in accordance with the invention, with 2 parts by weight of starch for 1 part by weight of casein. For this purpose, about 200 kg of casein in about 915 l of water, about 40 kg of ammonium hydroxide (28%), 12.5 kg of zinc sulfate heptahydrate in about 122 l of water, about 18 kg of ammonium hydroxide and about 12 kg of oleic acid were used. The oil-in-water emulsion was produced according to Comparative Experiment 2 with 800 kg of mineral spirits. Particle size 0.5 to 1.5, u. About 400 kg of an enzymatically digested starch were then added to the continuous phase of the emulsion, which in about 1,630 kg of water ^! Was heated to 88 to 90 ° C for 15 min. Eventually became a

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Clay slurry, solids 70%, from about 860 kg Clay including a dispersant is added to the emulsion. The temperatures corresponded to those in the example 1.

The viscosity values at different temperatures and under different shear conditions were as in Example 1 described, determined and plotted in Fig. 7 over the temperature.

Tabel

⁰ C comparison 2 cP • Temp. viscosity 100 rpm Viscosity index 10 rpm 40,000 21 71 200 14 600 32 21 200 6 400 1.45 43 12,000 3,000 , 1.88 50 6,000 5 2.00 Tabel ° C according to cP Temp. viscosity . 100 rpm Viscosity index 10 rpm 5,200 26th 28,000 4 5 20 5.4 34 27 200 4,000 6.0 39 21 200 3 480 5.2 47 20,000 5.7

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The stability of the coating slip according to example 2 is even more pronounced than in example 1 (starch casein 2: 1 compared to 1: 1), the mean viscosity index is higher; from this it follows that the coating slip according to the invention flows more easily under high shear stress and is therefore better for high-speed coating machines suitable.

This suitability was determined with the Massey coating machine. It is a device for coating inside the paper machine, with the. ■ Mass with large rubber rollers on the high-speed paper web is applied (see Ulimann, Encyklopadie der techn. Chemie, Vol. 13, pp. 134, 135).

The comparison products 1 and 2 did very poorly apply, they gave pronounced bumps and "crow's foot" patterns on the rollers and resulted in a very uneven application. In contrast, formed with the inventive Products according to Example 1 and Example 2 on the Transfer rollers uniform layers, the coated paper was essentially free of any pattern, i.e. a uniform coating is created. Test prints with both papers confirmed this. The compositions according to the invention result in a very smooth stroke and a usable one suitable for printing smoothness and even ink absorption, while the comparison products are lower Showed smoothness and a mottled appearance due to uneven paint pickup. There couldn't be any difference in the the paint adhesion can be determined.

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Example 3

A coating with a ratio of casein: Strength 1: 4 made from 45 kg 12% aqueous casein dispersion, Contains about 0.9 kg of ammonium hydroxide (28%) and about 1.8 kg of oleic acid.! 55 kg of xylene were obtained at about 49 ° C stirred in, then about 22 kg of oxidized starch in about. 66 l of water heated to 90 ° C. for 15 min and 66 ° C. of the casein solution at about 49 ° C. and then stirred in about 118 kg of 70% clay slurry, solids content

2
31%, thrust torque 4 dyn / cm, this is considerably below

that of a comparison mass of 12 dynes / cm with a solids content of 30%; from this it follows that there is even a still higher solids content could be achieved.

Both coating slips were applied to one side of a base paper and led to an increase in gloss by 2 to 3 % and opacity by 4 to 5% when applied

2
weight from 3 to 4.4 g / m. The printability of these coated papers was determined with the IGT printability tester (printing ink no. 3, printing speeds up to about 75 m / min). Test prints showed no different print smoothness. Other test prints showed that the coating slip according to the invention had a color absorption _f which corresponds to the usual coating slip, but is less than that of casein-containing masses.

As with other coating processes, the coated Paper can still be satin finished for smoothness and evenness

009830/1417

LA-28 239. - 27 -

and in some cases to improve the gloss. It can sometimes deteriorate optical properties come, but they are mostly low if the contact pressure is not too high.

FILE CLAIMS:

BATH

00-98-30 / 14-17

Claims (1)

DR.INCF.WUESTIIOFF 8 MUNICH OO DIPl-IKCCPULS SCHWEIOR-HSTRASSE ₂ DH.EvPECIIMANN ^TlLE "» ¹ 28 06 51 DR. INC D. BElIHENS usiioiiAMMADiiissm , _ IMIOTBCTl ATBKT Mt ¹ KCnEK PATKXTANWiI-TE Ρ 15 ^ 391.9 1A-28 239 July 15, 1969 Claims 1. Method of coating paper using a coating slip in the form of an oil-in-wasteer emulsion, wherein the continuous phase a film-forming binder such as a protein or an elastomer and a fine filler contains dispersed and the disperse phase is an organic liquid boiling over water, characterized in that an oil-in-water emulsion is used a droplet size of 0.5 to 1.5 / U is used, their continuous phase additionally contains gelatinized starch. 2. The method according to claim 1, characterized in that the coating mass is increased Temperature. 3 »Coating agents for carrying out the procedure according to Claim 1 in the form of an oil-in-water emulsion, wherein the continuous phase contains a film-forming binder such as protein or an elastomer and a fine filler dispersed and the disperse phase one over water is a boiling organic liquid, which means that g e k e η η, that the continuous phase gelatinized Contains starch and the disperse phase has a droplet size of about 0.5 to 1.5 yu. b. Coating agent according to claim 3, characterized by a binder: starch ratio between 1: and 1: 5 ·. · 5 · coating agent according to claim 3 or 4 characterized by a ratio of binder + starch to filler 1 ϊ 0.5 to 1 t k. . ■ 009830 / U17 lA-28 6. coating agent according to claim 3 to 5 characterized by a ratio of binder + starch to disperse phase 1: 1 to 1:10. 7. coating agent according to claim 3 to 6 geke η η ζ eich η et by a pesticide content of at least 20 '% .... 8. coating agent according to claim 3 to 7, characterized in that the filler is clay. 9. A method for producing the coating slip according to claim 2 to 8, characterized in that a dispersion or solution of the binder with the emulsified organic liquid and introduces filler and gelatinized starch into this pre-emulsion. 0.0 9 83.0 / UI 7 Blank page