DE1611786A1 - Process for the production of paper and similar cellulose materials with modified surface properties by electrostatic application of dry, powdery starch to the water-containing web moving past - Google Patents

Description

PATENTANWÄLTE 8 MÜNCHEN 2. HILBLESTRASSE 2O 161 1786

Dr. Owl dr Berg Dfpl.-Ing. Stapf, 8 Munich 2, Hilblestrasse 20

Our sign VIl / Er 16 ^ 932 _date

Attorney's file Mr. 16 932

Ransburg Electro-Coating Corp _o Indianapolis, Indiana / USA

Process for the production of paper and similar cellulose materials with modified surface properties by electrostatic application of dry, powdered starch to the water-containing one moving past

Train.

The invention relates to the production of flat Cellulosic material, such as paper and cardboard, for

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Creation of products in which the surface properties selectively by electrostatically applying dry starch in particulate form to the hydrous, fibrous Flat cellulose material, such as is used, for example, in the Fourdrinier machine, can be changed. The invention also encompasses the novel products which can thus be produced.

In the manufacture of paper and cardboard products, it is important to consider the physical properties of the product adapted to the intended use. For this reason, a variety of procedures and techniques created to measure the various physical properties of various sheet-like paper and paper To improve or control cardboard material. The essential properties include strength, stiffness, smoothness, Porosity and the propensity for different liquids such as absorbing water, oil, wax and paint or resisting their penetration »

In the case of printing papers, such as newsprint, one of the most important properties is the so-called fray resistance .

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and it is therefore a. Measure: for the surface strength. During the printing process, paint is applied to the surface of the sheet material by means of a printing plate, or in the case of offset printing by means of a gunmill transfer printing cloth or a rubber roller Adhesive surface fibers have the tendency to fray out of the surface of the sheet material and return to the plate or printing blanket _. Plate or blanket is removed, the tendency of the surface fibers to fray, -from the sheet material is greatly increased. Similarly, when using layers with higher tack, as is required in multicolor printing, the tendency of these fibers to fray increases greatly is extremely detrimental to the appearance of the printed area «. In less severe cases / will be affected by the

Individual fibers removed from the surface of the sheet material and collected on the printing plate .or, the printing blanket ,. if a sufficient number of fibers has been collected, they disturb the color distribution and a blotchy appearance results and unevenly printed area. It will then

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required to shut down the press> and clean it, which is both time consuming and laborious.

If the paper is to be used in connection with printing ink, it becomes dry due to absorption difficult problem * newspapers, for example, are almost always included Paint pressed $ soft by suction dries »The The surface of the "surface material must therefore not only Resistant but also be porous, so that the binder is absorbed in the color and thus the color is dried »while in the case of cardboard the inner Strength and rigidity are of the utmost importance, so are The surface properties are also important when the cardboard is used oppressed willows

! ei the iebfatichiiöheh method of * application of starch Is the table either "brewed" inside or as a a continuation egg? ttberaüg on the surface of the surface material bloated * This can be done by means of a variety being carried out by known procedures

iö The starch can be poured into the thin suspension of Fibers before they are delivered? Paper ^ maöchine eihgebr "eight Werdehj Whereby the dtihnflüösige suspension referred to as substance will*

2o The starch can be applied to the paper strand during the paper forming process on the paper machine wire mesh. Water spray or a similar application can be applied to the dewatering roller, which then transfers the starch to the paper surface _{or the like}

3ο The starch can be applied to the underside of the paper strand be applied by means of water spray, the Water spray up through the paper forming wire mesh is directed towards the underside of the sheet material.

4. Application can be by or between the press rolls be carried out by a suitable distribution facility "

5. The application of starch can be done with the leveling press take place between the drying rollers in the drying section of the paper machine.

6. The application of starch can be done at the Kaiänderwerk take place.

The benefits of any starch application method on the flat paper material depend on numerous Factors that determine the conditions prevailing in the paper machine, the type of unb.ehan.de It en web that is used in desired property of the finished surface material

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shafts and the properties of the starch product used lock in. For example, through a suitable chemical treatment, an added starch can become a cationic Possess charge which makes them noun of the paper fibers and what makes them in the sheet material or the paper web and not in the water which is removed from the paper web during the dewatering process will o in a similar way for the so-called surface applications The rheology of the starch is usually changed and controlled to make the starch better the one desired Puncture performs »

However, all of the aforementioned methods of applying starch have shortcomings relating to lack of uniformity, extensive use of starch, lack of economy due to the large amount of equipment required, requirements for high grades of highly modified starches, and the need to cook the starch before use . These deficiencies tre.ten especially when Oberflächenplanieren of the paper or cardboard, which are to be printed, and again particularly true when using colors of the absorption type _o when the strength is applied as a surface coating in an amount of which (to enlarge the surface strength Ausfaserungebeständigkeit ) is sufficient, the surface can

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iiiöiit that they have a degree of absorption capacity.

In relation to this, the present invention "is" znsbosondefe on the HiäMeMilg ätf surface properties of a fibrous * absörmifeiidinf f £ MtSMge & M§lltii6Bgmaterials' directed, * üM she tietifft iiiälaegöiiae're tie piänierungv-ön paper f how

In this way, the ötjefflöHefifgätigksiti, that is to say, the resistance to external fouling ^ bStraclitlioh increases wefdeiif oniie 'that the absorbency of the ötjefflöHefifgätigksiti' for the ¹ foul% egg is raised. e'inela Mer'kmäl dor Bifiiidting köiineü die> O "bei? flaenoEeigenSeMafteit: von faäerigefij fläöhigeffi Zöllülosemäteiiäi with e'ihe * ffl ger'ing & n Aii · ^ part of strength Weäentliek changed

A water-containing, fläöüigesj fibrous cellulose loosening is then carried out on a Mgdgrsöklaizöng vör'lgeibewegti and eiektröMätiädii charged liilöliin fön tröökeaer Strength will be given to this line! öken: butt each other ^ äiaj a? ämit si © gleiöäMliSig ve ^ töilt wördeiij wöliing on the other hand they are attracted to the iiäs ^ gü fäpiiiböte 'Weieili is effectively grounded * Jifitärlce te borrowed ii siöü iti eiiiiin elelEtlöStätisöheiä feldf Weleties 25Ü of the "PäpierBänn r ^ ieiitj ünt you -Werden äla finzelne ' llidS ^ geöcnlägens Bio Teilönen Besltäin di #

Tendency that they remain attached to the surface fibers, so that the surface properties of the treated paper or the treated paperboard can be selectively changed. The wet sheet material on its surface the starch particles have been precipitated is then heated to dry, and the precipitated Starch components adhere to the surface fibers and are thereby bonded to them. This process has proven itself as particularly advantageous for the production of paper, especially newsprint, in which the starch particles, which were precipitated, apparently through adhesion, selectively the rice protruding and upstanding surface fibers anchor, whereby these are the fibers that will be attached to the lightest fibers. In any case, an exceptionally low weight fraction of starch leads to remarkable increased strength of the surface of the paper without affecting the natural absorbency of the paper, which is modified, is changed significantly.

In the following, with reference to the drawing, exemplary embodiment-e the invention explained.

Pig, Fig. 1 is a perspective view of a conventional papermaking machine with devices for the precipitation of electrostatically

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charged particles on the paper web.

2 shows a partial sciiematic view of a modified embodiment for that of the electrostatic Precipitation of the starch particles on the paper.

Reference is now made to Figure 1 - One as a whole Fourdrinier machine denoted by ten has a head box 11, a headbox 12, a breast roll 15, Support rollers 14 and a GaUtsehwalze 15 around which the Wire mesh 16 migrates. The conventional dewatering roller can be provided if so desired. These However, roller is not shown »Furthermore, are conventional Suction boxes 17 are provided. When the paper web just formed leaves the wire mesh 16, it becomes the press rolls 18 and the felt cloths 19 »20 and; 21 moves, which transport the paper.

Since originally from the head box 11 to the wire mesh paper P applied in the vicinity of the breast roll 13 consists mostly of water, and the water content is increasingly done by drainage and then by suction to a water content of about 809S in the area the couch roll 15 lowered. After the paper has the

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Leaves the couch roll, it is led to a pressing section, where the press rollers 18 cooperate for further dewatering of the paper web, so that the water content of the paper is further reduced, and thus the internal strength of the sheet material is further increased. Last will the partially dewatered paper web led to the drying device D, which removes the moisture from the sheet material further reduced to the value desired for the finished product »

1 schematically shows an embodiment according to the invention, in which the electrostatically charged starch particles are deposited on the upper or the felt side of the paper P before the paper web is guided between the first pair of press rollers 18. It can be seen that the starch particles are supplied, as indicated by arrow 22, through a head piece 23 and then through pipes 24 to distribution heads 25 which are arranged over the surface of the paper P. A metered amount of finely divided starch is blown and scattered through the distribution heads 25. These particles are electrostatically charged so that they form a uniform cloud of starch particles in the chamber 26, which are driven towards the paper P as a result of their electrostatic charge , as has already been described .,

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Be the ^y orriehtung to apply the strength can at different locations along the path of movement. Föurdrinier-Drahtgewebea arranged You can be disposed of press rolls between or in place of a group, or they can press roll between the last! And arranged the Irocknungsabschnitt. In the same way, the starch application device can also be used the other way round and used for the electrostatic application of the starch particles to the undersurface or the wire mesh side of the paper, as indicated by the arrow 32 -Machine limited * Rather, it is advantageous in the same way for cylinder molding machines and other types of machine

In Figure 2 is the application of starch particles to both Pages of the wet paper sheet P shown, while the pa ^ - pier web is moved either vertically or horizontally. What be the case during their migration between adjacent pairs of press rolls 18. For explanation is on one side of the vertically moving paper web Fluidized bed 33 with electrostatically charged starch particles and a cloud of starch particles 34 is electrostatically moved away from the fluidized bed 33 and in contact transported with the wire mesh side of the wet paper to

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Another design for electrostatic deposition the starch particles on the vertically moving paper web is shown as a dusting device for the felt cloth side of the paper web. In this case the construction shown schematically in the form of an inclined platform 35 which, as indicated by the double-ended arrow 36, is vibrated so that a metered amount of particles in the vicinity of the paper web from the lower end of the platform 35 falls where the electrostatic charge - the particles this one Y / olke 3? can form, from which the starch particles electrostatically in contact with the wet paper be transported.,

As shown, electrostatic deposition of starch particles or granules in dosed quantities from a point above or below the wet Paper web can be achieved in various ways, such as the use of an inclined plate, which is vibrated to feed the starch and is charged to load the starch. Such constructions are in U.S. Patent 2,748,018. The usage of cannons for throwing or spraying dosed portions of electrostatically charged particles is preferred, such devices being commercially available and are described in a brochure called "Ransburg Electrostatic Powder Coating "and published in 1966

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was made public. These constructions can also be "for Application of starch on paper can be used if ... this moves in a vertical path section. In this lall can occur with the introduction of uncharged particles it happens' that no particles are deposited on the paper. When a charge is applied, the electrostatic motive forces control the flow speed of the material as well as the precipitation of particles on the paper. In the preferred case, the particles which are thrown against the paper are or falling on it, loaded. However, uncharged particles can also be used and charged on the way to the paper will. This can be done in that the Particles are passed through an electrostatic field.

When ^{adding a} starch in a dosed amount. · Is ^; it is appropriate to flow the dry starch particles with air, and the dispersion thus formed is blown to the distribution heads. However, other feed devices, such as a screw conveyor or a venturi pump according to the gravity system, can also be used.

The application of starch particles according to the invention can executed on one or both sides of the paper will. As already stated, according to a

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preferred form according to the invention the starch particles applied to the top or felt cloth side of the paper web «, It is observed that the wire mesh side of the paper web is usually much stronger than the felt cloth side, so that it is particularly sufficient in the newsprint industry. to modify only the felt cloth side of the paper and strengthen it so that a satisfactory product is created. On the other hand, and especially at When making finer types of paper, it may be desirable to have the starch particles on both sides of the paper To apply paper web, and this can also be done so.

The degree of bond between neighboring molecules in The natural starch granules are sufficient to make the granules relatively insoluble in and not sensitive to water are. Under the influence of heat, these become intermediate spirals Bonds loosened and to a large extent by binding of the starch molecules with the surrounding water replaced. The originally dense, hard starch molecules soak up water and swell many times their size original size. The swelling increases as the heating is increased or persists and eventually ruptures the granules and the formation of a uniform dispersion of hydrated starch particles occurs what is known as paste. So that an adhesive

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function is achieved in cellulose structures * it is not essential that the starch granules are fully gelatinized with complete breakdown of the granules associate-. The starch used according to the invention should be moisture- reactive to such an extent that it either already derates on contact with v-water, beX nortaaler room temperature or that it hyderat iäier t ödex "while under the moisture and TeBipBra'LrUrbrealngungen ens is partially swollen, which in the - fläciiermaterial if_ this dux-eii runs the srocknuiigsabsehabschnitt the paper machine "

The starch powder for the; electrostatic application can from amgelatinized starch granules, pregelatinized Starch, like drumming, he dries starch or ": r one _." Mixture of starch granules and pre-gelatinized starch be s telien. for use with a paper machine however, for continuous paper they turned out to be particularly good Results obtained when the starch powder is substantial consists of ungelatinized starch granules ire. With strength in grain form »which is dry when applied :, is; (the. normal interior moisture tileibil · not taken into account). every inclination of the broken strength becomes a festival »- glue ; η to cause the rolls of the paper machine "*

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reduced to a minimum value while at the same time the starch granules are given sufficient adhesive properties by the drying process so that the Surface strength and the resistance to fraying can be increased. During the degree of G-elatinization of the Granular starch on the gelatinization temperature of the starch in relation to the temperature of the paper web Depending on the drying section of the machine, the delatinizing and drying temperatures can be easy are so interrelated that the starch during the heat-drying process is only partially is gelatinized, whereby the starch granules are brought into adhesive relationship with the surface fibers and their Maintain granular structure, if pre-satinated starch is used, the applied starch absorbs water and can also be in adhesive relationship with the surface fibers be brought during the drying process » The use of pregelatinized starch makes the process independent of the drying temperature, and the usage; of pregelatinized starch is one increased solubility of the starch particles conducive, so that a more continuous surface treatment is achieved can be.

The gelatinization temperature given in the previous paragraph is represented by the viscosity of a

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Pulp of ungelatinized starch in water as a function of the temperature measured, the representation being a indicates increased viscosity once a temperature is reached at which the starch particles moisture absorb and swell. It is obvious that the according to the invention, starch used a gelatinization ρeratur should possess; which in relation to those temperatures is sufficiently low, which in the formation from paper or other cellulose webs, so that the deposited starch will eventually at least partially gelatinized so that they adhere to the F asers of the web is connected. According to a preferred embodiment of the invention, the starch particles are ungelatinized applied, and the gelatinization temperature of the starch is above the temperature of the water in the paper web.

That way and when the. When the temperature is increased in the drying section of the papermaking process, the starch particles are partially gelatinized and are not broken down, so that swollen, adherent particles are produced which maintain their particle shape in the bonded product, whereby the fibers which come into contact with the swelled starch particle are adhered to the base material of the sheet material connected to who can without the starch material under reduction

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the absorption capacity of the sheet material will ο

When carrying out the invention, the moisture content is the paper web at the point of application of the starch particles of relatively less importance for the invention Process as the humidity-temperature equilibrium in the drying section when this moisture is completely removed. As in the examples below shown, the moisture of the paper web at the time of starch application can change within wide limits while still satisfactory properties of the sheet material are achieved. In particular, a Moisture content from $ 25 to $ 95 parts by weight of Water or more can be used, however, it is preferable that the moisture content at the time of the Application of starch should be at least about 45 percent by weight, but preferably above 60 percent by weight should ο

The reason for this is that at moisture levels $ 45 or more gives the applied starch particles a better opportunity to soak up moisture, and to swell, so that the desired adhesive properties be created.

The electrostatic application of. Starch on the surface

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A paper cock is of unique disposition towards the procedures according to your state; the ilechhik accompanied, and vice versa f disgusting in "bemerlcenswerter'Weise many specialists _ \ parts of previous methods ^ In the fisrgaiig; according ER \ invention * _'; ^:.; /;" V-- "V"-'-'' ■■ ■ .-. "-". '".

Processes used up to now include the addition of starch to the paper stock before the. Formation of the -ann "a * lii the resulting surface material is the strength- -il-be-r; the" entire length of the "paper web is distributed, and often or mostly a noticeable improvement occurs as a result: the surface properties of the .I'flaechmateriala eiii «: ^; '

In a similar way / and when the Star Ice is cooked to form paste, which is the usual "procedure: 1st; the starch material is dispersed in the entire web material and thus contributes little to the surface properties of the surface. Darübaer hiuauS: will / the absorption capacity of the paper web is reduced to a significant extent by different distribution. This represents the situation in the case of so-called surface insulation applications wanders *;.; _v ;; ■ ^r ; ^ -

For applications with Walza application from-Stfke bxM a pa-

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pier surface is the rheology of starch material usually so that an uneven leveling film is applied and irregular surface properties result.

When using water nozzles to apply starch to the surface of sheet material, it is necessary to use a substantial amount of Vifassex in the material to be sprayed in order to improve distribution and to keep the viscosity at the required low level. As a result, an undesirably large amount of water must be used, and this water must be removed during the subsequent operations, thereby placing great stress on the press rolls and / or the drying devices. If the paper web is weak (especially in this case), the force exerted by the water nozzles can cause the paper web to tear, and this is particularly the case in the production of newspaper printers. Furthermore, the sprayed droplets have a tendency to deposit the starch particles unevenly. Interestingly, especially when ungelatinized starch particles are precipitated, these starch particles are very small and penetrate the interstices between the paper fibers, so that many precipitated particles cannot contribute directly to the surface properties. The ones in piles

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verbliebenen- on the surface of the particles tend to ^feed: sammenbaeken with other piles when heat is applied, and they do not bind the surface fibers to the base material of the paper web.

The application of dry powder to a wet paper web by mechanical "distribution" has been suggested but not commercially practiced. Such a process would be of dubious value because of the great air turbulence on the surface of a rapidly moving web. _; problem to be created, which could not be controlled by applicable devices, and would therefore lead to a considerable Prodüktverlust addition, the distribution properties are mechanically sprayed powder so that a uniform application is substantially impossible if such a method would be applied in strength.. Furthermore, the tendency of the starch powder to accumulate in heaps would probably produce an uneven effect ate the tiny particles of thickness ungelatinisierter not penetrate the paper web is waa leicht'verständlich when it is contemplated that the ungelatinised starch

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particles are generally not larger and often smaller than the diameter of the paper fibers making up the web. '

However, it has recently been reported that when aqueous starch dispersions are applied to flat paper, which only has 15 to 20 $ moisture in the web, the starch penetrates completely into the paper web. in the In contrast to this, according to the invention, the starch powder is applied to sheet material which has far more moisture possesses in the paper web without penetrating into the Paper web is perceptible.

The electrostatic precipitation used according to the invention The application of starch to the surface of a paper web is made possible by the turbulence of nearby air of the wire mesh is not particularly impaired. No dust occurs in the process, and almost all starch is applied to the web. In addition, the loaded and on the hike between the distribution facility and particles located in the paper web, so that they have no tendency to form agglomerates or lumps to form, and the resulting cloud of material is unusually uniform and flares up on the surface of the sheet material very evenly.

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The electrostatically charged starch components are attracted to the wet surface of the paper, and this attraction becomes that created by the air; Turbulence effectively overcome, which moves with the speed of the rapidly moving paper web., -. The merged starch particles remain on the surface of the paper and it is believed that selective deposition of starch takes place on those fibers which pass over the surface of the sheet material; protruding _tt These are the fibers that fray out most easily during the printing process and are removed by the surface provided with printing ink. It is believed that this phenomenon of selective precipitation on the critical points of the paper web contributes to the unexpected and greatly improved properties of the sheet material, which results from the use of small amounts of electrostatically deposited starch. It is also unusual and surprising that an improvement in the properties of the sheet material in the observed size is achieved, with the moderate degree of swelling of the starch, as is the case with the. according to the invention treated surfaces ^ aterialien was observed. This in turn can be a result of the fact that the starch remains on the surface and so it is not necessary to break the lights in order to bring the starch into contact with the surface fibers. One

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Microscopic examination of sheet material stained with iodine, which was prepared by the method according to the invention, revealed that the starch particles each individually to the Surface remain and are swollen in adhesive connection with the surface fibers of the paper, so that a discontinuous bond is achieved, which increases the strength at the surface of the sheet material without that a continuous film is formed, which reduces the absorption capacity of the sheet material: would. It appears that the starch utilization is considerable has been improved as the bond to the critical and important places. The uniformity of the distribution can be determined microscopically by comparing the number of the starch particles per unit area in different areas the surface of the paper. At microscopic magnification, the starch particles are of course not arranged in a regular pattern. These Uniformity can also be perceived with the eye, since every agglomeration of starch on the surface of the paper Would result in defects that can be recognized by the trained eye. Microscope examinations of pickled with iodine Products are usually magnified at 100x executed. ·

When applying the present invention, the strength

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amount which is applied "in a considerable amount Area to be changed in which there are still some advantages can be achieved according to the invention. Best possible / results with the lowest possible cost, however, result in Application of a relatively small amount of starch,

P P ~

such as 0.1 g / m to 0.5 g, thickness m / surface to be treated. In general, the method according to the invention

with an application of 0.1 g starch to 2.5 g starch per m Surface to be applied. According to the invention, maximum Results at a minimal cost in the range of 0.2g of starch

2 ■

up to 1 g of thickness per m of surface. "

Broadly speaking, the particles can have a size within a range of 16 to 118 meshes per cm, and even smaller particles can desirably be used. Preferably the particles have a size of .31 meshes per cm or smaller. But when the particles have an average diameter of one fifth to one tenth of the average width of the paper fibers have, so they can easily according to the invention be used.

The invention is carried out with Ha ^ d, the following examples explained ■

example 1

A reliable paper making machine more conventional

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Construction (which is similar to the machine shown in Pig. I) was provided with a plant for deposition of starch in a zone, the plant with the reference numerals 22, 23, 24, 25 and 26 corresponding to Pig. I is designated. The system is used to transport and electrostatically deposit finely divided starch onto the wet paper web. A single electrostatic distribution head 25 was used, which is arranged at a distance of 25 cm to 30 cm above the paper web. In the commercial art, however, wider paper webs would be made and more dispensing heads have been used to apply the starch across the full width of such wider paper webs than are shown in the drawing. The material used corresponded approximately to a conventional newsprint ( 7Qfo wood pulp, 30fo sulphite), and the finished sheet material weighed 14.5 kg per ream (61 cm by 91 cm - 500 sheets, 279 m ² ).

The papermaking machine is operated at a speed of 23 meters per minute and uncooked, powdered corn starch, which is used to lower its original gelatinization temperature to a! temperature was hydraxyethylated in the range from 6o 0 to 63 C, applied to the felt tape side of the paper, using an electrical charge of 65 to 67 KV on the heads.

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will be. The landing is applied by a churning device with negative spalling «" The starch parts are sieved so that particles with a size of more than 31 meshes per cm are removed. The system for applying "^; The starch application is arranged so that the starch is applied to the upper surface of the sheet material at a point between the last press rolls and the first drying roll * The moisture of the sheet material in this area is about $ 64. After the starch is applied the sheet material is continuously dried using drying rollers which are heated with steam at 2.1 atmospheres, and the dried sheet material is then calendered. The starch to be applied is metered so that the amount deposited is equal to one percent of the weight of the paper fibers , that means about 0.5 g / m surface. The finished]? Surfaces; .. materials are conditioned and tested according to the following tests by the Technical Association of Pulp & Paper Industry, which correspond to the standard: · T 459 ίί-48 (wax test for the surface strength of paper) '; T 499 su-64 (surface strength from paper IGi tester); RO - 19 (resistance of paper or cardboard to printing ink - Κ & Έ color); T 405 t- € 3 (burst strength .. of paper). In each case the IGi Tersuehe were made using a tacky paint Er. 3 (No. 3 tack ink) and a resilient drive 35 - B.

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The recorded values were with and against the Direction of manufacture of the paper achieved. The color absorption is expressed as the loss of surface brightness during the application of paint, as shown by a photovolt surface brightness test device (Model 61o - Photovolt Corporation, K.Y.O.).

According to starch wax-fraying IGT test Κ & Ή color A none 6-7 70/60 29.0

B. 0.5 g / M ² 12 220/340 27.5

The resistance to fraying of the surface, as evidenced by both the wax fraying test and the IGT test, is considerably improved. The color absorption, as revealed by the K & Ή color test, is insignificantly reduced.

Using the commercial hydroxyethylated corn starch sold by Penick and Ford, Limited under your Commercial name Penford Gum 300 was sold in achieved essentially the same results.

Example 2

The procedure of Example 1 is carried out using Repeated Penford Gum 580, which received a commercially-

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Borrowed representation of an uncooked, pulverized corn starch which has been modified by hydration to lower its original gelatinization temperature. and the powder is deposited successively in dosages at which 1 fo. 2 #> and 3 fo starch in terms of paser weight or 0.5 g, 1 g and 1.5 g starch per m Arches, surface fray resistance and color absorption tested as above with the following results:

L for thickness (g / m) Mullen test Wax fraying IQ-Q? . K&H

C none "·; ._ ■ 3.4 6 60/70 28.0

D 0.5 3.9 10 270/260 26.5

E 1.0 ".: 4.4; ^ - 11 290/370 25.5

Έ "1.5 3.6 11+ 300/340 25.5

These data machen.deutlich that the scrims nSize and Parbabsorption remain relatively unchanged, while the AusfaBerungsbeständigkeit when added was increased significantly from starch _o

Example 3

The procedure of Example_1 was repeated during

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the starch according to example 2 with * ~ Ltfo or about 0.5 g

ρ
Thickness per m was applied. In different parts of this run, the system for electrostatic application was arranged one after the other at (1), the same place as in Example 1, namely between the last press roll and the first drying roll, where the moisture of the sheet material was about 65%, at (< ?), immediately before the couch roll, as shown in Fig. 1, where the surface material ungeführ 8S contains fi humidity, and (3) wieter back to the paper machine wire mesh, where the moisture of the paper material about betrug- 94 $. In either case, the machine operation was completely satisfactory and the arching tests were relatively independent of the location of the application system.

Example 4

The procedure according to Example 1 was repeated again, but this time the starch according to Example 2 was electrostatically applied to the top of the sheet Aggregate knocked down, which is above the sheet material between the last press roll and the first drying roll was arranged. Next the strength was also at the Underside of the sheet material deposited by an aggregate, which is below the sheet material at the same

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Place was arranged. There were no operational problems and the previously observed improvement in the tests on the surface fray resistance was on both the top and the bottom of the "Flaciieniaate rials observed.

In the above examples, a small amount of tricresylphosphate, e.g. a free-flowing state of the starch particles be used. ■,.-_ ".--"

When offset printing newsprint, tropkne _: t; the 3? color mainly through absorption ». Thus it is important that ■ the corpse maintain the planar material in a state according to; which she 3? sore easily absorbed »; With the most effective method to date for improving the surface's resistance to fiber removal. namely, the surface was leveled with gei-cooked starches, the absorption properties of the surface material were usually appropriate. and such methods can be difficult to use when the strength of the sheet material, such as Iki Pail of duct paper, is insufficient. In contrast, and as shown by the examples, forms: by; an electrostatic deposition process according to the invention a solid and porous surface, and the larbab & option properties are only negligibly changed by this treatment;

^ 109813/0242 - _{% BÄD} original ~ ⁵² ~

As already stated, the strength used can be partially or pregelatinized, although ungelatinized starch is preferred. If a minor If a reduction in the absorption capacity of the paper is desired, the thickness should be chosen so that among the The application conditions used swell the starch particles and become adherent, but not broken up to any significant extent will. On the other hand, there are cases in which it is desirable, the Wasserauf satigungsbarkeit the Reduce paper to the lowest possible level, and in such cases the use of pregelatinized starch or partially gelatinized starch is that Breaking up of the starch particles and the subsequent distribution of the starch material over the surface areas of the sheet material.

According to the foregoing, and v / obei different strengths to better achieve different goals or to adapt different paper making conditions, such as the machine speed, the location of the starch application, the drying roller device and the The same can be preferred, different starches can of course be used alone or in mixtures with unmodified Corn starch, acid treated starch, oxidized starch, starch derivatives, tapioca starch, potato starch, Rice starch, pregelatinized starches, etc. are used

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will"

In connection with the above, it possesses unmodified Corn starch has a gelatinization temperature of about 70 71.5 0, and preferably corn starch is to be used which to lower their gelatinization temperature Facilitating their gelatinization during the papermaking process and the development of the desired adhesive properties has been modified. In this context it should be mentioned that the modification of corn starch or other starch with a high gelatinization temperature is desirable to lower the gelatinization temperature in a range from -12 ° ".C- to + 10 ° 0, preferably from -9 ° C to + 4 ° C is carried out. This can be done in a desirable manner by hydroxyethylation of the starch and in particular by Hydroxyethylation can be carried out, such starch modifications being well known per se.

It has been found that different strengths respond differently to the application of an electrostatic charge, both with regard to the decrease and retention of the charge to increase the precipitation efficiency and also with regard to the retention of a charge after the applied charge has been discharged through grounding. In this regard, it is desirable that the surface of _:.

1Ό9813 / 0242-;

starch used is treated to increase its surface conductivity so that a surface region is provided with increased conductivity which surrounds a core having a greater resistance or Dsolationseigenschaften ₀ Of course, not all the surface of the starch particles must have an increased conductivity. The use of starch particles which, according to their structure, have a surface area with increased conductivity and. having a more insulating part is preferable because it increases the ability of the particles to retain charge after deposition. It is particularly preferable to use starch particles which retain a positive charge after deposition. It is possible that this retained positive charge will contribute to the rapid and relatively complete bonding of the precipitated particles to the paper fibers on the surface of the paper web. It should be pointed out here that hydroxyethylation, for example hydroxyethylation, brings about an increase in conductivity and in many cases creates starch particles which retain a positive charge when they are charged with a negative voltage using a power supply unit and then grounded.

When the wet paper web is passed through the precipitation zone, it becomes an electrostatic one in this

- 35 -370242

~ 35 ■ -

lelcl according to the loaded distribution heads. exposed. These heads are used to build a box with yours transparent potential gradients of at least 2 and preferably 2-4 KV. per cm of distance j where the distance between the distribution heads and. the surface the effectively grounded paper web: geiaderu-It should be noted that the paper web, the electrical 'field is subject, which ■ a ield concentration around the; can cause protruding surface fibers, or the field can be another, have a similar effect on the mass of the paper web? to the observed phenomenon according to which the starch particles on. of the surface In connection with the papler fibers stay and not in large quantities in the paper web penetrate, contributes., Due to the high moisture content of the paper web at the point of the low particle base and due to the very small size of the Deposited starch particles would have this effect not to be expected in itself. ; .-;

Of course, the application of starch particles according to the invention simultaneously with the application of others certain materials; take place: which with the strength- particles can be mixed with and with these; together angry weraeii can. These other particular materials include dyes, fillers, and particles

of polymers that are compatible with the selected strength such as mixtures of starch with polyvinyl alcohol, Polyvinyl acetate, and copolymers of styrene and butadiene are compatible.,

The invention thus enables the production of paper and similar products with modified surface properties by precipitation of electrostatically charged particles of dry strength on a water-containing one Paper web that is still on the wire mesh of a Fourdrinier machine. The starch particles can be used as uniformly distributed, individual particles precipitated which remain on the surface of the paper and are swollen with the water of the web when the web is dried so that the surface fibers with the paper material get connected. For the adhesive function it is not necessary that the particles gelatinize until they break are. The paper, especially newspaper papiers, retains its Porosity. Because the strength is not in the paper material penetrates and is present in the form of individual particles the surface binding effect is increased despite the lower amount of starch.

The invention is not intended to be restricted by exemplary embodiments be.

- 37 -

Claims 1098 13/02 42

Claims (1)

1611785 Patent claims Process for the production of a fibrous, flat cellulose material susceptible to absorption, characterized in that that a water-containing web of fibrous, flat Cellulosic material at a particle precipitation zone is passed that the precipitation zone dry and for mutual repulsion electrostatically charged particles are fed, whereby the starch particles are electrostatically attracted to the wet web and uniformly in lorm of separate particles are deposited on it, and that the web is then drained. . Method according to claim 1, characterized in that the Starch particles are ungelatinized, and that the wet web is heated to dry it, whereby the starch particles at least partially gelatinized with the water of the web. '".: ■ 3. The method according to claim 1, characterized in that the starch parts in a dosage of 0.1 g to 2.5 g Thickness per square meter of surface to be deposited. 4. The method according to claim 1, characterized in that the starch particles are designed so that they have a conductive Have a surface and a part with reduced conductivity « 10981370242 - 38 - 5. Procedure according to. Claim 1, characterized in that the Starch consists essentially of ungelatinized granular starch. 6c method according to claim 5, characterized in that the. Starch is corn starch which has been treated to reduce the gelatinization temperature on its surface to -12 ° to + 1O ⁰ O. 7. The method according to claim 6, characterized in that the corn starch is hydroxyäthliert on the surface. 8. The method according to claim 1, characterized in that the water-containing paper web contains at least 25 percent by weight of water. 9. The method according to claim 1, characterized in that the sheet material is selected from the group comprising paper or cardboard. Ioο method according to claim 1, characterized in that the surface material is paper. 11ο method according to claim 1, characterized in that dae Fläohenmaterial is newsprint. : yes ^ .o ^ o ^ ^a /: - 39 - 109813/0242 - ... . ^ V-S ^ f-. : - - 101178S. - <> Process for the production of; Paper, characterized in that a water-containing paper case ^; with at least -25 Gewiclitsproaeiiten water at a precipitation zone for. Partially • is moved forward so that the precipitation zone / for the. ' Particles of dry täriceteoiLchen in a dosage of; _S is g to 2.5 g of starch per m surface supplied that the starch particles are loaded for mutual Albstossung 'electrostatically, so that the starch particles are electrostatically sucked to the wet web and on this in the form of individual particles, are uniformly deposited: 0.1 As a result, the paper fibers are heated up by means of drainage, whereby the starch particles are at least partially gelatinized with the water in the web and adhere to the surface fibers of the paper 13. The method according to itnspruch 12, characterized in that the paper is newsprint, and that the starch particles ' which are fed to the UiedersChlagzöhe, ungelatini - "_-- siert and in a dosage of about 0.2" to . about 1.0 g of starch per square meter of surface area. · 14o, method according to claim 12, characterized in that the .stärketeilchen are formed in such a way that they have a conductive surface and a part with reduced XeIt- have the ability and that they are electrostatically charged; so that they retain a positive charge after precipitation. . ., f "■ _ 40 - 15o procedure according to. Claim 12, characterized in that the moisture content of the web at the location of the particle precipitation is at least 45 percent by weight, 16. The method according to claim 12, characterized in that the starch particles ungelatinized at the point of precipitation . are sated and on a water-containing paper web with at least 60 percent by weight of water are precipitated * 17. The method according to claim 12, characterized in that the Particles of the precipitation zone for the particles are metered and fed onto the wet paper web from above the same will be knocked down. 18c method according to claim 12, characterized in that the electrostatically charged starch particles on the free upper. Surface of the ^ paper to be deposited when this is carried by the Fourdrinler wire mesh. 19. Procedure for selectively changing surface properties of fibrous, flat cellulose material that is susceptible to absorption, if it is in the form of a water-containing sheet is moved, characterized in that the water-containing surface web In a precipitation zone with an electrical . ■ -4X- 109813/0242 Ί6Μ7 & 6 static field is carried out, that a, stream, of dry Starch powder is directed to the sheet that the Starch particles in the 'current to repel one another are electrostatically charged while they are off the train are attracted, that thereby individual starch particles are deposited on the surface in a substantially uniformly distributed manner, that the sheet is subjected to heat drying subject we α, whereby the precipitated starch particles, connected to the surface fibers with adhesion will. , 20-8 · Method according to claim 19, characterized in that the starch powder in the directed stream essentially ' contains ungelatinized starch granules. . ; 21. The method according to claim 19, characterized in that the precipitation zone with an electrostatic field has average potential gradients of at least 2 KV volts per cm. 22 Process for treating at least one surface of flat material in the manufacture of fibrous, .-- .. absorptioiisfahigein, flat cellulose material paper or Cardboard, the sheet material as a continuous water-containing web with a top and a bottom surface is formed and the web is subjected to heat drying, ■: - ■ ■ · ■■■. :.: ■; · "■ · - 42 109813/02 42 characterized in that the wet web prior to heat drying through an electrostatic precipitation zone is directed that a spray of dry starch powder on at least one surface of the web and substantially is directed across the width thereof, the starch particles forming the spray mist for mutual repulsion electrostatically are charged while they are attracted to the wet web so that they are essentially on it uniformly distributed and precipitated as individual starch particles that the individually precipitated Starch parts are essentially separated on the surface sit and touch the wet surface fibers, and that after that the wet web is covered with separate starch particles its surface is subjected to heat drying so that the starch particles are in adhesive relationship with the surface fibers are brought and that these adhere during the heat drying process. 23ο Method according to claim 22, characterized in that the sheet material is newsprint and that the starch powder is sprayed onto the wet web of newsprint. 24ο Method according to claim 22, characterized in that the starch powder in the directed stream comprises essentially ungelatinized starch granules that the granules at least partially gelatinized during heat drying 109813/0242 ~ ⁴³ " will,; and that the starch powder is on the top surface the web in a dosage of at least 0.2 g to 1.0 g Thickness per m surface is sprayed ο 'A method for improving the resistance to fiberization of newsprint without significantly reducing its absorption capacity, characterized in that a water-containing web of newsprint with at least 25% by weight of water is passed into a precipitation zone with an electrostatic field that a stream of dry starch powder the top surface of the web at a dosage of substantially 0 ^ 2 g to 1.0 g 2 * · ■ "" ■ "■" " Thickness per m of surface is directed so that the starch particles in the current are electrostatically charged to collide with one another, d they are attracted to the web, whereby substantially uniformly distributed, individual starch particles are deposited on the surface of the web are that the particles adhere electrostatically to surface fibers of the web, that the web is subjected to a heat drying so that the starch particles swell with the water of the web, while essentially maintaining the granular structure of the starch particles, whereby the starch particles remain separated from each other and in the essentially stick to the surface of the newsprint with the binding of fibers of the newsprint to the base material. 109813/0242 - 44 - - .-. ■■ - 44 - 1611788 26. Paper web, characterized in that at least one side of her strength part in a dosage of at least 0.1 g of starch deposited per square meter of surface are that the starch particles are at least partially gelatinized and in adhesive relationship with the fibers stand on the surface of the paper, and that the majority the starch particles on the paper are separated from each other o 27. Paper sheet according to claim 26, characterized in that the starch particles in a dosage of 0.2 g to 1.0 g 2
Starch particles are deposited per square meter of surface area, and wherein at least 75% of the deposited starch particles can be observed to be separate from one another, and with substantially all of the starch particles being on the surface of the paper. 28. Newsprint, characterized in that on the felt cloth side of the newsprint starch particles in a do- At least 0.1 g of starch per square meter of surface are that the starch particles are at least partially adhering to the fibers on the surface of the Newsprint are gelatinized, being essentially all of the starch particles are on the surface of the newsprint and with the majority of the starch particles are separated from each other on the surface. 29. Newsprint according to claim 28, characterized in that 109813/0242 - 45 y ■ - 45 - the starch particles are corn starch particles which are so modified are that the gelatinization temperature -12 ° C to + 1O ⁰ C is reduced, and that the starch part - - 2 pieces in a dosage of 0.2 g - 1.0 g starch per m Surface are down. 3Oo papermaking machine, characterized by that V
a device is provided for feeding the wet paper web past a precipitation zone for particles, that means for feeding electrostatically charged starch particles to the precipitation zone of the particles is provided, as a result of which these charged particles are attracted to the paper web in the form of single particles and be evenly distributed on this. ; 31. Apparatus according to claim 30, characterized in that the precipitation zone is arranged above the free upper surface of the paper when it is carried by the lOurdrinier wire mesh. ^: 1098 13/0242 Blank page