DE1212835B - Method and device for producing a glossy coating paper - Google Patents

Description

Method and apparatus for making a glossy coating paper The invention relates to the manufacture of a gloss coating paper product, where the term "paper product" means any type of paper, either printed or unprinted, plastic films from z. B. cellulose and its derivatives, metal foils made of z. B. Aluminum or tin, cardboard of any kind, composite materials made of cardboard and one or several laminated paper layers, paper webs or cut sheets of any desired Size as well as individual boxes made of printed or unprinted cardboard.

In making a coating paper product, it is highly desirable to that the coating offers high gloss and still of all the appearance and usability is free from imperfections that could impair wax paper. So far it has been customary To produce glossy wax coating paper in such a way that the paper web immediately after the wax application by passing it through a cold water bath, by applying finely quenched with a cold air stream or by cooling rolls. This method however, it has numerous disadvantages. In the case of water quenching, one achieves with some coating recipes glossy effect, but appear on the wax surface with increasing production speed, more and more so-called »crow's feet« appear. The usual quenching rollers do not achieve a high gloss.

Another possible coating process is the so-called »molding coating«. Here, the paper web is coated with melted wax, the wax layer solidified and in contact with a smooth, polished mold surface then peeled the wax-coated paper from the mold surface. In this procedure there is a risk that the paper web due to poor synchronization the rollers and paper web advancement relative to the forming roller surface and shifts therefore the crystallizing one, especially at high machine speeds and solidifying waxy layer of their smoothness and regularity as well as theirs Shine is more or less deprived. In addition, the Rollers run so slowly that the wax mass can solidify, and when. Unroll there is a "pull-off" of the wax-coated web from the roller; H. a transfer of wax particles from the coating onto the roller. This accumulation of coating particles Impairs the effectiveness of the mold surface during subsequent roll revolutions.

These problems that occur during molding over are presumably based on several factors. For a given paper speed, it hangs the achievable gloss level depends, among other things, on the bond between the coating substance and paper product, from the release properties of the coating substance or the molding surface or both and on the tensile strength of the coating substance itself.

In contrast to these known measures, the invention is based on noting that a smooth glossy wax-coated paper product will have: high production speed can be obtained in such a way that one heated, applying molten coating substance to a paper product and during its molding subjected to a "quench cooling" on a part of an endless molded element, which is achieved by the fact that the coated paper product with the help of the still molten coating substance in immobile relationship with the endless form element is brought, which is a mirror-smoothed at the contact point with the coating substance Has surface.

Accordingly, the method of the present invention for obtaining a glossy coating paper product is in which one side of the paper product is in intimate contact with a layer of thermoplastic, congealable coating substance by pressing both against a mirror-smooth surface a fast moving, endless molding member is brought, said layer is in a molten, plastic state and in adhesive contact with the mold surface is brought to by pressing evenly between paper product and mold surface to be distributed: characterized in that the surface of the molded member to a temperature below the melting point of the coating substance and at the same time also the paper product during its contact with the reverse side of the form member'- through,? retrograde. Application of a fluid whose temperature., Likewise. - is below the substance's melting point, the paper product and the Mold member during this process of cooling and solidifying the coating on the mold surface are moved in such a way that the paper product, coating and molding surface are intimate and immobile Stay in contact and -no cooling-. fluidum penetrate between the coating and the mold surface can, - and - the cooling continued until the substance solidifies and afterwards the cooled, coated paper product is peeled from the mold member.

This method can be carried out with a device that is characterized by an endless shaped element -with an internally cooled, smooth, highly polished surface for removing a heated thermoplastic Substance-coated paper product and for rapid cooling of the coating to a temperature below the melting point of the substance, this surface being with on. to come into contact with the heated coating located on the paper and able to cling to him; an application device for 'liquid to cool the the opposite side in contact with the molding member surface Side of the finite coated paper product and one of the cooled mold member surface Adjacent heated pressure roller, which forms a continuous gap with ... through which the coated paper product at the point of entry to the cooling surface these pressed and thereby immovable; form-fitting adhesive contact - with the Cooling surface is brought. - The essential feature of the method according to the invention and the device according to the invention consists in a "shock" cooling treatment, in which the cover paper product through a cold molding and at the same time: through a cold mass of liquid is cooled. This “feature” is missing in all of them so far known devices of this type. The method according to the invention makes it possible the rapid cooling of the product adhering to the forming roll and allows thus performing the molding operation at an exceptionally high speed. - Likewise, the crystallization of the thermoplastic material is due to both Surfaces of the paper product acting cooling = by means of uniform and results in a surface that: a scarring. over long periods of time able to withstand. If the thermoplastic coating is only on one side is cooled; '' the wax or the like begins on the intermediate layer between to crystallize him and- the one coolant, and -this crystallization progresses inward-.fort. However, since the crystals located on the intermediate layer are faster are formed than those lying deeper in the coating, there may be differences in the Properties of the inner and the crystals present on the intermediate layer occur. If, on the other hand, the coating is cooled from both sides, it is. very. much true- ' ScheMcliei,: däß. The crystals are formed on both sides and are therefore essential less tendency to form crystals with different properties or there is a faulty grid. . . . . ,. -. Apparently the melted The quench cooling causes the coating substance to quickly reach its melting range to go through and to crystallize and .thereby an unusually shiny Form surface. The quench cooling is also used for rapid solidification of the coating between the paper product and the mold surface and thereby creates between them a.-liability, which any tendency to reduce the gloss or even destructive relative movement. As a result, the paper product processed at high speed and then made high-gloss. Experience has shown that the advantage is that when the speed of the paper product is increased the gloss is also improved accordingly - if the coated paper product is subjected to a quench cooling. In addition, the coating develops due to the reason the rapid cooling at high paper product speeds such a tensile strength, that any transfer of coating substance to the mold element and any premature Bracing of the same as a result of poor synchronization between the rollers and the paper product is avoided.

The paper covering substance used in the present invention is preferable a thermoplastic material such as' e.g. B. paraffin wax, microcrystalline wax, Low molecular weight polyethylene between about 2,000 and 21,000 - and preferably between 3,000 and 15,000 or polygropylene. Besides polyethylene there are others thermoplastic resins such as polyamides; Polyterpenes, petroleum resins or other resins with thermoplastic properties, useful. Furthermore, mixtures can also be used of two or more of the foregoing materials, such as a combination made of paraffin wax and microcrystalline wax or polyethylene can be used. Of course, as a paper product coating, the material must have gloss and protective properties have and must not have a melting point so high that it is the paper product somehow -damage. In general, the choice of the particular coating substance depends depends on the type of paper product. The benefits of using polyethylene in the case of coating compounds, more or less are known. In connection with paraffin and / or microcrystalline wax, it improves the toughness of the resulting coating, prevents it when the coated paper is rolled up, it sticks together and gives a higher gloss and: better bending and sealing properties, etc. The amount of coating substance is usually sufficient to create a layer thickness of about. 2.5 to 635 [.. With a composition of z. B. 50 parts by weight of paraffin (m.p. 60 to 63 ° C) and 50 parts by weight of microcrystalline wax (melting point 63 to 64 ° C) -can coating substance can be used in an amount of 24.4 to 488 g / m2 paper surface.

. Another advantage of the invention is that at the same time Use of polyethylene and low-melting, sticky, microcrystalline Wax. (For the purpose of high sealing properties and low-temperature flexibility ) - iri. - Wax coating the proportion of polyethylene is low, d. H. about under 5 to down to about 0.1 percent by weight, are kept kärin. As a result, at Use. an economic saving can be achieved with this resin; 'with the usual equipment and procedures, e.g. B. when using chrome-plated or other metal surfaces, cannot be reached because experience has shown that coatings with such a low polyethylene content unsuccessful on such surfaces @ can be applied. Obviously, the invention is related to the coating recipe less sensitive than other conventional processes. `- The feature surface In addition to the smoothness of the mirror, it preferably has the property that it drops below when it cools down the crystallization temperature of the coating substance adheres to it only so weakly, that the coated paper product can be easily peeled off from the forming member. Accordingly should there be enough adhesion between the coating and the forming roller; that despite the immersion of the coated paper product entering a cold bath upon quench cooling excess moisture between the coating and the roller and the resulting dark Stains on the upper surface of the coating are avoided. In addition, this liability must also any relative movement between the endless forming element and the paper product as a result of poor movement synchronization of both.

Usually this occurs when peeling off the coated paper product from the cold forming roller to considerable difficulties. This includes in particular the chipping of the coating from the paper product due to its excessive adhesion the forming roll surface. The adhesion can be so great that when the paper product is peeled off tearing from the roll surface, d. H. an actual transition of at least Divide the coating to enter the mold. The one that accumulates on the surface of the mold Coating substance affects the impression and thus also the quality of the product. Such chipping and / or transfer of the coating, which is part of the The mold surface and partly adheres to the paper product is obviously unsatisfactory. It proves that the tensile strength of the coating substance is lower than the adhesion of the Coating is on the forming roll or that the coating substance on the paper product is less than adheres to the mold surface. Sometimes they take from the printed paper Coating particles peeled off from the paper product and transferred to the mold surface Printer's ink with what proves that the adhesion of the printer's ink to the paper is less than that of the coating on the forming roll: one such phenomenon is also highly unsatisfactory.

Other problems can also arise. In insufficient cases Adhesion of the roll cover layer to the roll body can be peeled off during operation of the coated paper also cause this top layer to tear off from the roller, Other materials show poor expansion and construction properties - at. Changes in temperature and tend to crack. Some layers of material are too soft and are easily damaged and scratched as a result. Another The disadvantage is the insufficient water tightness of the covering layer or the covering layer Adhesive to hold the top layer on the forming roller. Certain materials only provide poor gloss on the coated paper product, and others in turn do not give a smooth coating at all. The most common difficulty however, the poor peeling property of the layer material is that it tears off or chipping of the coating on the paper product, etc.

According to the present invention, it has been found that by coating the forming roll surface with a layer or film of a material having precisely defined properties as described later, satisfactory cooling of the coated paper product can be achieved while avoiding the aforementioned difficulties and disadvantages. The cover layer on the forming roll surface thus ensures a convenient and safe detachment of the coated paper product. It is defined by a certain adhesion to the coated paper product, which can be canceled by applying a certain force. As determined by experiments. is the force required to peel or peel a 102 mm wide strip of coated paper from a metal plate covered with a topcoat or film. It is in the range between 2 and 20 g and preferably between 4 and 12 g. In this experiment, the heated coating substance is first applied to the paper strip, the coated strips are attached to the coated metal plate and the plate and the strips are cooled in water and only then is the force required to peel off the paper measured. This is done by attaching one end of the strip to a dynamometer, pulling the strip off the plate and noting the force required to do so. Any other suitable spring balance can be used instead of a dynamometer. It should be pointed out that if the release force values are too high, when the coated paper print is peeled off from the mold surface, tearing occurs and if the release force values are too low, the paper product does not adhere adequately to the roller surface, i.e. does not cling to it sufficiently and possibly slides relative to it. Regardless of the composition of the paper product coating, a cover layer material is preferably used for the form surface, the release value of which is in the specified ranges. With such a material, the paper product can be peeled off the mold surface without weakening the coating adhesion to the paper product. Of course, these release values apply to the working temperatures of the mold surface. It is also important that the top layer or top film material adheres to the paper product just enough to hold the product immovable relative to the roller. If there is any relative movement between the paper product and the roller, when the roller rotates in the liquid bath, water can enter between its cover layer and the paper product coating, thus preventing the formation of a smooth glossy coating on the paper product for temperature changes between 0 and 121 ° C. Its thermal expansion, measured according to test D 696 of the American Society of Testing Materials, is preferably 1.25-10-3 to 2.5-10-s MM / "C. Since the If the forming roller rotates at least once a second, the material must also be able to withstand temperature changes from 0 to 121 ° C in a short time of no more than one second.

The top layer must be on the inside of the polished, rigid steel surface the cold roller very firmly and in any case more strongly than the paper cover to it. In addition, the outer layer must be smooth, preferably shiny; mirror-smoothed Surface.

The top layer must also be so hard - that it can be easily destroyed able to withstand. The internal toughness or tensile strength of the top layer exceeds the adhesiveness of the wax-coated paper to its outside.

The layer must be waterproof and its substance not water-absorbing to be softened or warped by the water or the liquid bath to avoid.

Among the numerous plastic materials with these aforementioned Properties and advantages include in particular the known or urethane polymers Polyurethanes as a reaction product of an organic polyisocyanate with a polyfunctional, reactive hydrogen containing compound. These materials will in the presence of a basic catalyst to influence the polyurethane formation capable of being implemented.

Another class of plastic materials consists of the polystyrenes including the polymers formed by the polymerization of styrene. The polystyrene is preferably oriented, so it consists of material that cools within of the orientation temperature range was drawn. The plastic material can either only in one direction or - simultaneously in transverse and longitudinal resin has been hardened.

Acrylic acid polymers represent another group of suitable plastic ones Materials represent; The polymers of methacrylic acid are related to them. Esters too the acrylic and methacrylic acids, e.g. B. methyl acrylate and methyl methacrylate provide in polymerized form are useful materials. As an example of such plastic Materials may be mentioned a butylinethacrylate polymer, which is preferably with 10 to 20 weight percent nitrocellulose resins was cured.

Other plastic materials consist of polyvinyl acetals that obtained by condensation of polyvinyl alcohol with an aldehyde. For this belong e.g. B. polyvinyl acetal, polyvinyl formal and especially polyvinyl butyral.

Vinyl resins including vinyl chloride, vinyl acetate, and vinyl chloride-vinyl acetate resins are also suitable.

Modified ones are also suitable plastic materials Polyester (alkyd) resins. The above-described polyesters can by reaction with other materials such as urea-formaldehyde and / or melamine-formaldehyde resins forming what are commonly referred to as alkyd urea or alkyd melamine resins Products are modified. Other modifiers are fatty acids or containing them Oils, e.g. B. coconut oil or castor oil, from which oil-modified alkydurea and Alkyd melamine resins can be obtained. Alkyd melamine resins modified with coconut oil are very good gloss generators and do not cause any tearing at all.

The plastic layer can be applied to the roller in any desired manner, depending on the type of plastic material. For example, plastic in sheet form can be wrapped around the roller and attached to it with a waterproof adhesive. Granular or powdered plastics can be dissolved in a solvent and cleaned by brushing, spraying .or. Like. Be applied. . The layer thickness varies between approx. 0.013 and 3.2 mm and is preferably between 0.025 and 0.076 mm: The invention will now be explained in more detail with reference to the drawings. It shows F i g. 1 shows a schematic representation of a preferred application system for obtaining the improved, coated paper product according to the invention, in particular in the form of a paper web, FIG. 2A shows a diagrammatic representation of a modified method for carrying out the production of individual cardboard sections according to the invention, FIG. 2B shows a diagrammatic representation of a further modified method, FIG. 2 C and 2D diagrammatic representations of modified process steps of the various processes, FIG. 2 E is a diagrammatic representation of yet another method, FIG. 3 A is a diagrammatic overall representation of a method for carrying out the invention, and FIG. 3 B shows a diagrammatic overall representation of a further, modified method.

The in F i g. 1 shown application system consists of two waxing rollers 1 for spreading the molten coating substance on both sides of the paper product as it passes through these rollers. Then the melted coating mass guided away under a heated polishing steel roller2 and thereby further on the Paper product surface distributed. The paper product then runs over an example consisting of rubber pressure roller 3 and over large surface areas a large one Form roller 4, from which it is then returned with the aid of a soft rubber deflection roller 5 is deducted.

The casting roll 4 can be operated at high speed and delivers a high gloss coated paper product at, for example, a peel speed from about 305 m / min. With a roll diameter of 1.83 m, this corresponds to production speed from 305 m / min. a roller revolution of about 1.1 seconds, while with one roller 0.45 m in diameter, one rotation only takes 0.3 seconds.

The forming roller 4 is brought to a surface temperature by brine circulating on the inside slightly above 0 to about 21 ° C and thus generally below the melting point of Coating substance held.

The roller 4 and the paper product surrounding it are immersed in it cold liquid bath 6, the temperature of which is also below the melting point of the coating substance lies. Ordinary cold water is preferably used as the bath liquid Water with a temperature of 0 to 21 ° C, but cold saline solution is also suitable for this. The temperature of the bath liquid is preferably below that of the. Roll surface 4th Instead of water, there are other liquids for the bathroom 6 suitable. These include, for example, aqueous solutions with a low content at z. B. ethylene glycol, popylene glycol, isopropyl alcohol, ethyl alcohol, isoamyl alcohol etc. or mixtures thereof. As an additive, e'.n wetting agents, such as sodium lauryl sulfate, Dioctyl sodium sulfosuccinate, certain alkyl aryl sodium sulfonates, etc., serve. That Water, on the other hand, can also be replaced by other liquids, e.g. B. ethyl alcohol replaced which, of course, must not dissolve the plastic cold roll coating.

In that the temperature of the liquid bath is preferably lower than that of the forming roll surface is held, more rapid heat exchange occurs in which more heat units per unit of time are derived from the hot wax coating will. The colder surface of the mold results in a stronger quench cooling. It can be seen when the bath liquid is colder than the mold surface is to have a larger temperature gradient in the paper to be cooled.

For the purpose of reliably avoiding relative movements between the paper product, Coating and forming roller 4, this is preferably driven directly, while the Pressure roller 3 and the take-off roller 5 only by contacting the forming roller 4 via the intervening paper web and its cover are taken. The pressure roller 3 is preferably at a temperature above the melting point of the coating substance held to keep the coating surface complementary to the forming roll surface. Accordingly, the pressure roller 3 is held just above the cold bath surface, to avoid any premature solidification of the molten coating substance, before their surface adapts to that of the molding element or the cold roll 4 Has. This surface adaptation is achieved by pressing the roller 3 directly against the Form roller 4 guaranteed.

The take-off roller 5 is also arranged above the cold bath surface and pressed to after peeling the paper product from the mold surface any To prevent moisture build-up on this. Special attention must be paid to this will. In addition, the take-off roller 5 and the forming roller 4 should be practically parallel Have axes so that the coated paper product without any eccentricity peeled off the forming roll and any distortion of the coating surface and distortion of the paper product is avoided.

Although the quench cooling during the laying of the paper product and its coating substance on the cold roll surface 4 is quite strong preferably a conventional chill roll mill 7 and a doctor blade 8 are used, to cool the coating substance with certainty to the point that it will after winding of the paper product on a supply roller is not "blocked" or remains sticky. Thus, by the large-caliber quenching roller 4 in connection with the cold bath 6 the coating substance crystallizes by rapidly passing through its melting range and by being considerably hypothermic below their melting point of any effective Exempted heat content. The subsequent cooling roller section 7 is used for further cooling of the coating so that it does not block in any way and thereby the achieved gloss what remains is that all migration tendencies of the coating substance after winding of the coated paper product can be suppressed on a supply roller.

The invention also enables the series production of individual boxes or cardboard blanks with a smooth glossy coating made of thermoplastic material.

The invention creates a method for rapid series production of high-gloss cardboard with the help of the work steps described in more detail later which is the thermoplastic that is applied to the cardboard blank from the molten bath Substance is cooled rapidly. The invention is characterized in particular by that by coating individual cardboard blanks, the coated ones are rubbed off Avoid surfaces and reduce the waste caused by this and otherwise can be. However, such coated waste is in contrast to non-coating waste not usable again.

The method shown diagrammatically in FIGS. 2A to 2E for Extraction of individual boxes with a smooth glossy coating made of thermoplastic substance is generally that on one side of successive, individual Cardboard blanks have a coating of molten substance applied and each individual blank with the still plastic substance located on it one after the other into the intake area a pressure roller and a cold forming roller of the type previously described are thus introduced becomes that its coated side comes into close contact with the forming roller. These The forming roller has a mirror-smooth top layer on which the adjacent blank side adheres and is thereby made immobile relative to the roller. As a result of the forming roll rotation the blank is snuggled tightly by a pressure roller, whereby the coating substance is distributed uniformly on the cardboard base. The forming roll surface becomes kept at a temperature below the substance's melting point, whereby the coating is rapidly cooled on the blank. The continued going around the forming roller serves to hold the blank on its uncoated side with at least to bring a body of coolant into contact, thereby the coating further to cool off. During its rigid union with the cooled forming roll the blank is cooled down by them and the body of coolant for so long until the coating has solidified with certainty and then the blank as One side with a smooth glossy coating made of thermoplastic material Body can be pulled off the forming roller.

In Fig. 2A, a cardboard blank 10a is accordingly delivered from a supply, not shown, to a conveyor belt 11 and conveyed by the latter into an application zone 12, where it runs through a series of application rollers, as can be seen from the blanks 10b and 10 drawn in plan on their side edge c is shown. The application rollers consist of the upper and lower rollers 16, 18 and 20 arranged in pairs, the lower rollers dipping somewhat into a molten bath 21 made of thermoplastic material, the vessel 22 of which is heated by means not shown. That way. Cardboard piece 10c coated on one side with plastic substance is placed somewhat in the downward direction on a cooled forming roller 4 in such a way that its coated side rests against the roller surface and adheres to it. This Foim.walze 4 has a mirror-smooth surface on which the blank is arranged in a rigid manner. When the forming roller continues to rotate, the blank gets into the nip between the roller 4 and a soft rubber pressure roller 3, which presses each blank tightly against the forming roller surface and thereby distributes the covering punch evenly between the blank and forming roller surface.

The cold forming roller 4 is conventional and therefore not shown Cooled by brine circulating on the inside. The temperature of the cold roll depends depends on the thermoplastic coating substance used in each case, but lies in in each case below their melting point and in particular in the range between 0 and 21 ° C. The lower temperature limit is expediently chosen so that ice formation is avoided on the forming roll surface. The upper temperature limit is preferably at 4.4 ° C. The coating on the blanks becomes fast after contact with the cold roller cooled down. This, due to its rapid course, can also be described as a deterrent The cooling process is explained in more detail below.

After attaching the blank to the forming roller, it will be at further roller revolution downwards into the area of a coolant spray mist or stream 25, which preferably consists of a channel 26 or the like. On the uncoated There is a water jet running up on the cut side, and then for the purpose of further Cooling of the coating in a cold liquid bath 6 in a vessel 28 is promoted. Reference should be made in particular to the diaphragm 29, which directs the cold water flow to the blank 10 d points out and thereby an impact of water on the pressure roller 3 or on the roller surface 4 immediately adjacent to this pressure roller 3.

Each cut, e.g. B. the blanks 10 e and 10 f remains so long in the cold liquid bath 6 until the coating has definitely set. Obviously During these cooling processes, the blanks remain motionless with the forming roll surface tied together.

Through the combination of the internally cooled forming roller 4 and the cold water jet 25 and the cold liquid bath 6 is the one located on the blank, hot Coating substance removed heat so quickly that a high production rate is possible.

After leaving the liquid bath 6, the blanks are conveyed upwards into the intake gap between the forming roller 4 and a soft rubber squeezing roller 5, which removes the excess water from the non-coating side of the blank. removed, and then detached from the forming roller 3 by means of a scraper 34. The loose blanks 10g, 10 h, 10 i fall from the roller on a conveyor belt 35th

The depth of immersion of the forming roller in the liquid bath is adjustable, however, the water must not touch the squeegee roller 5. Due to the deep Arrangement of the roller 5 in relation to the axis of rotation of the forming roller 4 is achieved, that the detached blanks are at least partially on the conveyor belt by gravity 35 fall down.

The smooth forming roller surface required to create the high gloss is preferably through a top layer in the form of a coherent, hard, shiny and extremely smooth material layer of the type described earlier achieved that has good release properties, i.e. easy peeling off of the coated blank Allowed by the roller. This can also be expressed in such a way that the blank cover although it has good adhesion with respect to the forming roller, it is less than the internal toughness of the coating and its adhesive force on the blank. the Form roll cover layer has such a high degree of smoothness that a blank cover can be produced with a continuous surface. If necessary, the Roller 4 also consists of a polished metal roller or a nickel or chrome-plated one Roller consist. In general, the molding surface of the cold roll should be mirror-finished and their surface area should be below the melting point of the blank coating lying temperatures only exert such a low adhesive force on the coating that the coated blank can easily be pulled off the roller.

Optionally, but not preferably, the chill roll can 4 can be replaced by an endless belt with a mirror-smooth surface.

The pressure roller 3 is by constant heating during contact with the blanks kept at a temperature above the coating melting point. As a result, this roller holds the coating each in the inlet gap between it and Roller 4 of incoming blank (see Fig. 2A) in a practically plastic state and smooths and levels it by pressing it against the smooth surface of the roller 4, so that it finally gets a high gloss finish.

The removal of the blank from the roller 4 is carried out with the aid of the this roller pressing soft rubber roller 5 regulated. The axes of rotation of both rollers 5 and 4 are practically parallel to each other, eliminating any oblique peeling and any distortion of the coating can be avoided.

The coolant located in the container 6 can be made of ordinary cold. Water from about 0 to about. 16 ° C or, of course, also consist of cooling liquor. The same applies to the liquid flow 25 discharged from the channel 26.

The above information regarding rollers 3, 4 and 5 and the bath 6 according to FIG. 2A also apply to the corresponding elements in FIGS. 2 B to 2E.

Depending on the caliber and temperature of the forming roller, quantity and temperature the running and standing coolant can be run at throughput speeds from 61 to 152 m / min. to be worked.

In all of the process modifications described below, several series of cuts can be processed at the same time. For example, in FIG. 2A, several wax application devices can be arranged next to one another, i.e. parallel to one another, which feed the blanks covered by them in parallel rows of two or three, etc., to the correspondingly broadly dimensioned rollers 4 and 3. The blanks cooled in the manner described earlier. can then be detached from the forming roller by means of a correspondingly large number of stripping cutters or air nozzles and one or more cooperating squeegee rollers and then placed on a common conveyor belt of the appropriate width or on several narrower conveyor belts.

F i g. 2B shows a modification of the invention in which there is no water flow or jet used, but by immersing the forming roller 4 in deeper the cooling bath 6 extends the stay of the blanks in the cooling bath and thereby a increased cooling of the coating is guaranteed. Otherwise, the procedure according to FIG. 2 B as well as yours according to FIG. 2 A worked, and therefore are identically acting elements are denoted by the same reference numerals. Obviously however, in the method according to FIG. 2A due to the lower position of the squeegee roller 5 the conveyor belt 35 can be moved closer to the cooling bath 28. For the sake of clarity Illustration is in FIG. 2 B the applicator device 12 only indicated and the dem Conveyor belt 11 according to FIG. 2A corresponding element is omitted.

In Fig. 2 C shows a further modification of the invention, in the case of separating the intermediate pieces from the forming roller 4 instead of the doctor blade 34 an air nozzle 40 is used, the air jet of which on top of that detached in each case Blank blows over onto the conveyor belt, not shown. In addition, the Air jet can also be used to remove any water droplets from the mold surface.

In Fig. 2D shows yet another, particularly preferred modification of the invention, in which both a knife 34 and an air nozzle 40 are used to separate the blank 10g from the forming roller 4. The knife represents a simple mechanical device for clean cutting off, while the air jet supports this process and on top of that offers the advantages described above. Therefore, understandably, the knife-air nozzle combination can also be used in the systems according to FIG. 2 B and 2 A can be used.

In the case of the in FIG. In the embodiment of the invention shown in FIG. 2E, the blanks 10 g are stripped from the forming roller 4 below the liquid level in the cooling vessel 28, in which case both the stripping knife 34 and the conveyor system 35, 35 a are arranged. The detached blanks 10 h, 10 between an upper conveyor 35 and lower conveyor belt 35a i conveyed out of the bath and with the aid of two over the Kühliiüssigkeitsspiegel arranged pressing rolls 39, 39a freed of excess liquid. Obviously, the process shown in FIG. 2 E the transfer of a detached blank onto the conveyor belt, because the detachment takes place in the lower half of the forming roller and the upward rotating roller gives the loosening blank a movement impulse in the direction of the conveyor belt 35a . Furthermore, as a result of its arrangement at or near the separation point, the conveyor belt 35 a supports the blank on its path of movement to the delivery zone on the other side of the squeegee rollers 39 and 39 a. An air nozzle 40 can also be used with the forming roll 4 to remove any water from its surface. . For the sake of clarity, the application device 12 is only partially shown in FIG. 2E and the feed conveyor belt 11 is completely omitted.

To specifically explain the invention, it should be mentioned that the raw material For the blanks from printed or unprinted, single-layer cardboard, from paper-laminated cardboard Cardboard with glue as an adhesive or made of any other material, which has been refined with a high-gloss coating.

In the case of cardboard boxes whose flaps have to be glued, leaves If necessary, the wax coating can be removed, for example by conventional steaming locally distant from the flaps <.

Papers suitable according to the invention usually consist of printable papers Paper from 13 to 146 g square meter weight and in particular comprise papers from chemically derived pulp including sulphate, sulphite, sulphite and sulphate Soda papers without or with one or both sides coated with alumina, titanium dioxide and binders; furthermore calendered or calendered pulp or Pulp-wood pulp mixed papers with or without coating, including newsprint, Glassine or calendered sulphite paper, SUlflt sulphate paper with a machine finish and optionally machine shine. Cellulose films, such as Cellophane and cellulose acetate, as well as aluminum or tin foils are suitable.

As a cardboard base material are z. B. pure cellulose board, such as bleached and unbleached kraft paper, soda and sulphite cardboard, cardboard made from optionally bleached semi-chemical cellulose such as medium corrugated cardboard, cardboard made from waste materials such as Schnitzel and jute cardboard, and mixed cardboard made from waste, wood pulp and pulp, z. B. with a thin mineral layer of about 80% newsprint and 20% bleached fiber coated newspaper board, double manila board, wood pulp core board and double-bleached, laminated wood pulp waste core cardboard suitable, cardboard of this type are usually identified by their basis weight and strength points (1 point = 25.4 1st t). Accordingly, all of the above types of cardboard are located in the range from 98 to 781 g / m2 and 40 to 50 points.

The amount of the coating substance of the type described earlier is sufficient for usually consists of covering each blank with a 25.4 to 635 #t thick layer overlay. A coating compound made of, for example, 50 parts by weight of paraffin (m.p. 60 to 63 ° C) and 50 parts by weight of microcrystalline wax (melting point 63 to 64 ° C) can be applied to the blank in an amount of about 4.8 to 488 g / m2 Every coated blank has an extremely shiny, smooth and even appearance Surface that is completely free of defects such as the so-called crow's feet. Of the The term "coating evenness" means that the finished carton can be used at a later date has good resistance to water vapor penetration. Also protects the coating protects the cardboard from abrasion and prevents it, especially when it is printed Paper an undesired transfer of printing ink to non-printed areas, for example by fingerprint. In addition, the coating improves the end product irr with regard to humidity and the like.

The in the F i g. 3 A and 3 B diagrammatically shown, adapted Embodiment of the principle of the invention allows the production of a at least partially impregnated composite packing material with a smooth high-gloss coating on one side of thermoplasticein material, and in particular the inexpensive manufacture of paper packaging material for folding boxes with a high-gloss surface and other protective properties that were previously only producible at considerably higher costs.

This variant of the invention combines those for producing the packaging material required work steps of impregnation, coagulation and coating of paper and cardboard layers in one operation on a comparatively fast one Machine and thus replaces the previously usual, separate three process operations. The process also provides economic savings in terms of equipment and Raw material.

This variant of the method consists essentially in the fact that a continuous. Paper web initially for the purpose of double-sided impregnation and coating through a Bath with molten coating substance and then with a still plastic coating a first constriction zone is passed in which the material to be distributed on the web Amount of substance is adjusted or regulated. Then the web becomes a second, formed by a heated rubber pressure roller and a cold forming roller Constriction zone supplied and together with a continuous, possibly also cardboard web impregnated or coated with coating substance through this zone passed through. Here there is a composite effect on the two, during the run aligned webs. Next, the composite web will swift or subjected to shock-like cooling, with the coated paper outside comes into close contact with and adheres to the cold roll surface. How later is explained in more detail, here the cold roll causes a uniform distribution of the coating substance on the side of the paper layer adhering to the roller, a solidification the composite web coverings and the generation of high gloss on the paper-side cover. According to FIG. 3A becomes a continuous paper web 10 from a supply roll 51 withdrawn and via a guide roller 52 in the melt 21 contained in the vessel 22 a thermoplastic coating substance to a steering roller arranged in the weld pool 55 around, at least a little further in the melt pool and finally over steering rollers 56 and 57 out of it. Simultaneously with the melt pool 21 passing through Paper web 10 is a continuous cardboard web 10 'from a supply roll 51' _ unwound, one in the molten bath 21 and resting on the outside of the paper web also guided around the steering roller 55. Then she runs a longer distance long freely through the weld pool and leaves it after being deflected by a guide roller 60 to finally together with the paper web 10 in the nip between two Rollers 62, 62a to enter.

It can be seen that the paper and cardboard webs are at the entrance into the molten bath 21, and further through during the greater part of its travel through the melt and finally separated from each other when leaving the same. These Measure facilitates web handling and reduces any occurrence of Folds, flutter movements and periodic gluing and separating processes or switches this off. Both tracks are impregnated with wax in the weld pool and on both sides overdrawn. The purpose of the impregnation is to fill the cavities and spaces be understood in the interior of the near-surface web areas with wax. The application the coatings on the webs, on the other hand, enable their subsequent lamination and the later high-gloss production on the outside of the paper layer.

The two tracks 10 and 10 'are moved over the rollers by their movement 62 and 62a brought into mutual surface contact to an increasing extent and during the passage through the roller slot, which under more precisely mutual Alignment done, laminated. The lower roller 62a is made of steel and the upper roller 62 made of rubber. They are usually called nippers because they are not only used for railway association, but at the same time also for the "measurement", i. H. Regulating the creation of a serve good union required amount of coating. Because every train already brought a piece in front of the roller slot with its associated roller in contact air is excluded from the connecting web surfaces, eliminating any Wrinkling in the composite web 10 "is avoided. All excess coating substance is removed from the underside of the paperboard layer by a doctor blade 64 and guided back into the bath vessel 22 with the aid of a collecting lip 65. The laminated Web 10 ″, the coatings of which, in particular the paper side, are still plastic then over a heated rubber pressure roller 3 into the inlet slot between her and the cold forming roller 4, whereby the coated paper layer outside 10a comes into close contact with the cold roll due to the plasticity of the coating adheres to its surface and is thereby coupled to the roller in a rigid manner will. The cold roll 4 has a mirror-smooth surface, which by inside the roller circulating brine is cooled. The device required for this is of a known type and therefore not shown. The cold roll temperature of the cooled The roller depends on the type of web coating and is always below it Melting point, so z. B. between just above 0 and 21 ° C. The lower temperature limit must be chosen so that no ice formation occurs on the roll surface. the the upper temperature limit is preferably 4.4 ° C. Immediately after emergence Rapid cooling of the paper-side coating occurs on the cold roll. This Because of its rapidity, the cooling step, which can be designated as quench cooling, has already been used explained in more detail above and forms an essential feature of the invention.

The pressure roller 3 presses the coating 10 a against the smooth roller surface 4 and thereby ensures its uniform distribution and smoothing, while the mirror-smoothed forming roller surface gives it a high gloss at the same time. In order to achieve this, the coating must still be plastic when it runs onto the cold roller 4, and therefore the path of the paper web 10 ″ between the rollers 62, 62a to the cold roller 4 is kept as short as possible and the coating is again made using the heated pressure roller 3 The gap between the rollers 3 and 4 acts as a second lamination zone.

The coated composite web 10 ° 'runs in contact with the cold roller surface 4 and also through the cooling bath 6 for such a long distance that the coatings are cooled below their melting point and the aforementioned smoothing and high-gloss processes are brought about. In this case, too, the forming roller 4 revolves in a vessel 28 filled with the cooling liquid 6 and thereby takes the composite web with it into the cooling bath. As a result, the paper-side coating 10 a resting on the cold roller 4 is applied from both sides, that is to say directly through the cold roller surface on the one hand. and on the other hand, indirectly cooled from the free cardboard side through the composite web by the water bath 6. During this cooling of all the coatings, the composite web remains in motion-stiff support on the cold roll 4. After exiting the water bath, the web runs through a nip between the forming roll 4 and a soft rubber squeezing roll 5 and is freed from the water adhering to the cardboard side. At the same time, this nip roller 5 supports the detachment of the composite web from the latter by its pressure on the forming roller 4 without damaging the coating 10 a. The parallel arrangement of the two roller axes of rotation avoids any inclined pulling off of the composite band, any distortion of the coating and any tearing of the web. Finally, the composite web is guided via a guide roller 66 to a supply roll (not shown).

In this installation, too, the cold roll 4 preferably has a self-contained, extremely smooth surface covering layer. This cover layer, which consists of material previously described in detail, has good release properties, so the coated web can easily be detached from the roller. It has such a high degree of smoothness that the paper-side film or coating 10a is given a uniform surface. If desired, the forming roller 4 can also be a polished metal or nickel or chrome-plated roller. In general, the molding end of the cold roll surface should be mirror-finished and, when cooled below the melting point of the paper-side coating, adhere only so weakly to the coating that the coated web can be easily peeled off.

Optionally, but not preferably, the cold roll be replaced by an endless belt with a mirror-smooth surface.

In the embodiment according to FIG. 3B, the web 10 is guided from a supply roll 51 via a guide roll 52 into the bath 21 of thermoplastic coating substance contained in the vessel 22 and through guide rolls 55 and 56 arranged in the bath through the same and out again. Both sides of the web are impregnated and coated with the coating material. The web treated in this way now passes through the gap between two rollers 62, 62a, which, as in the embodiment according to FIG. 3 A regulates the amount of coating on the web. The vessel lip 65 catches any spray liquid thrown off by the high-speed web and guides it back into the bath. The web 10, which is still covered with a plastic coating, now runs over a deflection roller 70 into the gap between the cold roller 4 and a heated rubber pressure roller 3, where it meets the cardboard web 10 ' fed from the supply roller 51' via the guide rollers 71 and 72 . Both tracks run in register between the rollers 4 and 3 and are laminated in the process. Even before it enters the nip, the coating located on the outer or upper side of the paper ply 10 comes into close contact with the surface of the forming roller and adheres to it. This adhesion is supported by the pressure of the rubber roller 3, which, as in the case of roller 3 according to FIG. 3 A is generated by compressed air cylinders, not shown. The effect resulting from the rotation of the forming roller 4 in the cold water bath 6 corresponds practically to that of the roller 4 in the arrangement according to FIG. 3 A. The finished composite web 10 " finally leaves the cooling bath .6 and runs through a slot between the roller 4 and a rubber squeezing roller 5 and over a deflection roller 66 to a take-up roller, not shown.

Obviously, in the system according to Fi g. 3 B only a single lamellar constriction, namely the gap between the rollers 4 and 3, is present. Preferably, the web 10 only comes into contact with the roller 4 practically at the same time as it enters this gap, whereby on the one hand the wax coating on the web 10 is kept warm and thus plastic for as long as possible and on the other hand it is ensured that the web lamination only shortly before cooling takes place on the forming roller. If desired, the thickness of the coating on the web 10 can also be regulated by so-called Mayer rods arranged on both sides of the web instead of by the nip rollers 62, 62a.

The usual devices are used in both composite railway systems. However, additional equipment would be required when impregnating, Laminating and coating would be done in separate process steps.

For cardboard products with a high degree of impermeability to water and water vapor, the method according to FIG. 1 is best suited. 3 A manufactured raw material. If the inner or cardboard side of the cardboard does not necessarily need to be impermeable to water and water vapor, but rather only moderately, this is done according to the method according to FIG. 3 B produced raw material is preferred. Incidentally, this material is also particularly suitable for producing cardboard boxes with glued flaps, since the composite web 10 ″ according to FIG. 3 B can easily be dewaxed for the purpose of creating such flaps.

The web 10 can be made of suitable, mostly printable paper or without imprint. Such papers have a weight between 13 and 146 g / m2.

On the other hand, the web 10 'can consist of cardboard with a weight per square meter lying between 98 and 781 g and 5 to 40 strength points (with 1 point = 25.4 #t).

Regarding the composition of paper and cardboard and their equivalents For exchange materials, what has been said earlier applies.

In the method according to FIG. 3 A is the required amount of coating up to 161 g and with the one shown in FIG. 3 B only 65 g per square meter of surface: the coated composite sheet has an extremely shiny, smooth and uniform surface that is completely free from defects such as B. "Crow's Feet", is. The uniformity of the coating means that the packaging material produces at later use has a good resistance to water vapor penetration and especially for folding boxes for storing food, such as gelatine, Flour products, buttery foods, frozen foods, etc. These Cardboard boxes have a high-gloss, attractive appearance and are resistant to water or water Water vapor penetrates both diagonally and along a cardboard wall, like that in the latter case due to wicking at a cardboard corner is possible by, for example Water vapor enters the cut edges of a cardboard flap and along it could penetrate the inside of the box through their cavities. According to the invention manufactured cartons are also characterized by their cheap raw material including Paper and cardboard, especially thermoplastic material, e.g. B. wax, in place the otherwise necessary, expensive material in the form of a soluble varnish. Through the The coating according to the invention is also the cardboard against abrasion and in the case of printed Outside against smearing and transfer of the printing ink by fingerprint Protected on unprinted areas. In addition, the coating also improves the airtightness of the cardboard, etc. increased.

Example A paper web with a molten coating composition about 50 parts by weight of paraffin (m.p. about 60 to 63 ° C) and 50 parts by weight microcrystalline wax (melting point approx. 63 to 64 ° C) is applied to a paper or cardboard web applied with a weight of 24.4 g up to 488 g / m2. Preferably the coating compound still some polyethylene with an average molecular weight of about 2000 to 21000 added, because experience shows that it is on the one hand to a certain extent -decreases the tendency of a coating to block and, on the other hand, its high gloss reinforced. The optionally coated paper has a thickness of 0.0254 to 0.635 mm. When using the above-mentioned preferred coating compound the rubber pressure roller 3 is preferably heated to 66 to 121 ° C, so that the coating mass is certainly sufficiently melted and plastic to maintain the smoothness of the forming roll surface 4 to be able to accept. The rubber pressure roller and the squeegee roller preferably have both have a caliber of 10.2 to 25.4 cm and the forming roller 4 has a caliber of 45.7 Up to 183 cm: The forming roller covered over a wide area of the circumference with the paper web immersed in a cold water bath during operation; the anti-freeze is more organic Nature, e.g. B. ethylene glycol, are added to make it ice-free even at low temperatures to keep. The cold roll 4 itself can with a coolant, e.g. B. Sole, so deep be cooled down so that their temperature is sufficiently low below the crystallization point the coating mass remains.

The pressure roller 3 is pressed against the cold roller 4 with a force of 9 to 36 kg / cm 2 and preferably has a durometer hardness. from 60 to 100 Shore A, in order to apply the coating mass evenly and as a continuous film to the smooth surface of the forming roller 4. In this case, however, the coating compound must not begin to crystallize before it has assumed the smoothness of the forming rolls. The coating compound is then rapidly cooled both by the cooling bath and by the cold roller and its heat content is absorbed by both cooling media so quickly that the wax quickly changes from the plastic to the crystalline state with the formation of very small crystals. The rapid solidification of the coating mass brought about by the quenching has the consequence that between the paper web, the coating and the forming roller surface there can be no or only a negligibly small relative movement. The coating solidifies on the smooth mold surface with only very little adhesion and can therefore be removed from the cold roller surface effortlessly and without errors by pulling the coated paper over the take-off roller 5. When using the above-mentioned, preferred coating compositions, the cooling rollers can rotate at extremely high speeds and produce a high-gloss coating paper at production speeds of 305 m / min and above.

The paper web coated in this way is cooled to about 46 ° C or below, the doctor blade 8 serving to keep everything condensed on the paper surface or otherwise remove any accumulated moisture.

The subclaims are only in connection with the main claim below Protection provided.

Claims (15)

Claims: 1. A method of making a glossy coating paper product, in which one side of the paper product is in intimate contact with a layer of thermoplastic, congealable coating substance by pressing both against a mirror-smooth surface a fast moving, endless molding member is brought, said layer is in a molten, plastic state and in adhesive contact with the mold surface is brought to by pressing evenly between the paper product and the mold surface to be distributed, d a d u r c h g e - indicates that the surface of the mold member to a temperature below the melting point of the coating substance and at the same time thus also the paper product during its contact with the rear side of the molding member by applying a fluid to the back, the temperature of which is also below of the substance's melting point, the paper product and the molded member are cooled during this process of cooling and solidification of the coating on the mold surface are moved in such a way that the paper product, coating and molding surface are intimate and immobile Stay in contact and no cooling fluid can penetrate between the coating and the mold surface can, and the cooling continued until the substance solidifies and thereafter the cooled, coated paper product is peeled from the mold member. 2. Procedure according to claim 1, characterized in that the endless shaped member is a highly polished Roll is used with a forming surface that is circulated by a inside the roll Lye is cooled. . 3. The method according to claim 2, characterized in that that a polyurethane layer continuously drawn around the roller as the molding surface contacted and adhered to the heated coating of the paper product is brought. 4. The method according to any one of the preceding claims, characterized in, that the molding member while the paper product and the coating agent are in contact with it stand, immersed in a volume of cold liquid that is on a substantially temperature lying below the melting point of the coating agent, preferably between 0 and 21 ° C. 5. The method according to claim 4, characterized in that that the liquid water, an alcohol or an aqueous solution with an additive is used. 6. The method according to any one of claims 2 to 5, characterized in that that the coated paper product around most of the circumference the highly polished roller is arranged around and this roller as well as that on your current paper product is immersed in the cold liquid so far, that a solidification of the coating agent is effected. 7. Procedure according to one of the preceding claims, characterized in that the paper product is a paper web is. B. Method according to claim 7, characterized in that the paper web on is provided with a coating on both sides, the one facing away from the molded member The side provided overlay serves to protect the paper, while the latter protects the liquid is exposed. 9. The method according to any one of claims 1 to 6, characterized in that that the paper product consists of a series of spaced apart longitudinally arranged, individual cardboard blanks. 10. Device for performing the method according to one of the preceding claims, characterized by an endless molding member (4) with an internally cooled, smooth, highly polished surface for making contact with a paper product (10) coated with a heated thermoplastic substance and for cooling the Coating to a temperature below the melting point of the substance, this surface being able to come into contact with the heated coating on the paper and to adhere to it, as well as by an application device for liquid (6) for cooling the other, not to the The side of the coated paper product (10) adhering to the surface of the molded member and through a heated pressure roller (3) which is adjacent to the cooled surface of the molded member (4) and forms a passage gap with it, by which the coated paper product is pressed against the cooling surface at the point of insertion and thereby in immobile, form-fitting ssige adhesive contact is brought with the cooling surface. 11. The device according to claim 10, characterized in that that the pressure roller (3) can be heated to a temperature of up to 149 ° C. 12. Device according to claim 10 or 11, characterized in that it is a cold liquid bath (6), in which the lower part of the mold member (4) is movably immersed, so that the liquid of the bath with the exposed outside of the adhered paper product (10) is in contact. 13. The device according to claim 12, characterized in that that the temperature of the bath (6) is lower than that of the mold surface (4). 14. Device according to one of claims 10 to 13, characterized in that it has a device (26) for supplying cold water (25) to the outer, uncoated side of the paper product (10) after it has passed the pressure roller (3) and a Deflection device (29) to prevent wetting of the pressure roller and the forming roller surface between this and the point of introduction of the paper product onto the forming roller (4) by the water. 15. Device according to one of claims 10 to 14, characterized in that the forming roller (4) is surrounded by an uninterrupted polyurethane layer which can come into contact with the heated coating of the paper product (10) and adhere to it. Documents considered: German Patent No. 702 867; French Patent No. 986 032; U.S. Patent Nos. 2,443,221, 2,559,649, 2753275.