DE1496602C - Electrostatic process for producing single or multi-colored patterns, especially on glass objects - Google Patents

Description

The invention relates to an electrostatic method for producing monochrome or multicolored Patterns, in particular on glass objects, in which electrically chargeable particles are attached to a carrier in are applied to the pattern mirror-inverted shape and then the particles by means of a electrostatic field are transferred from the carrier to the surface to be printed, whereupon the Pattern is fixed on the surface.

When coating or decorating glass objects, a colored glass frit is applied in known processes to the finished glass objects and the object is then heated in an oven in order to burn the coating onto the glass or to fuse it with it. The application of the frit to the glass can be accomplished by several known methods. For example, the screen printing process for frit in paste form is known or the spraying on of a frit which is dispersed in an aqueous binder, generally in a mixture of water and alcohol.

With these different processes, the glass object must first be shaped, tempered and tested, before the frit can be applied and fired or melted. If more than one color is applied, then successive printing operations must be carried out for the separate forms, and each of these processes is followed by a separate heating process, around the frit to attach to the glass. In addition, when applying successive coating layers Great care must be taken to achieve accurate alignment of the successive colors. This method therefore requires much manual labor and high cost.

In electrophotography, it is also known (German Patent 813 359) to form a latent powder image on an insulating layer that is on a PCB is attached. The powder image on the insulating layer is created by dusting one on the Insulating layer formed electrostatic image. The powder image made up of powder particles can be removed from the insulating layer transferred to another surface and fixed by means of an electrostatic field.

It is also known to provide ceramic objects with a coating of enamel powder, which is sprayed on from nozzles using an electrostatic field. For better adhesion of the Powder it is also known to spray the workpiece to the melting temperature of the powder to heat.

In contrast, the invention is based on the object of producing patterns in particular To simplify glass objects and to enable the production of multi-colored patterns.

Based on the method described at the outset, this object is thereby achieved according to the invention solved that the particles by per se known methods directly on an electrically conductive Carrier applied and charged by applying the electrostatic field and when moving, in which the surface and the carrier are led past each other in strips, transferred to the surface will.

In contrast to / to the well-known electrophotographic Printing process, the method according to the invention does not form a latent image more electrostatically Charges and does not require the dusting of subsequently charged particles on the electrostatic charged surface. Rather, the new process removes the pressure particles first formed into a coherent pattern on the carrier according to the image to be printed, followed by the electrostatic transfer of the particles in the desired image arrangement takes place directly on the surface to be patterned. The deposited particles in the final print assembly can then be applied to the surface of the printed medium in any desired shape that is known in the art, e.g. B. by heating, steam melting, covering with a transparent Coating or the like. To be fixed.

Thus, the particles do not need to be electrostatically attracted or aligned to form the powder image to become, but the particles will be after making the pattern on the electrically conductive Carriers are electrostatically attracted towards the printing surface in their predetermined relationship in the image. This difference is essential and of decisive importance for several embodiments of the invention, as this for the first time the production of the pattern on the carrier by any mechanical or triboelectric processes, for example stenciling, screen printing, rubbing or the like., is made possible. It can thus be a large part of the electrostatic device and essentially the entire device for handling the particles at the point where the actual printing process should take place in omission. This considerably simplifies the device and enables the automation of the image forming process to be carried out on the carrier in one location which is removed from the pressure point.

Furthermore, multicolored patterns can be formed by simultaneous or successive attraction of multicolored particles in a desired, precisely matching orientation on the surface to be printed, with only one printing process being required. This brings about a considerable simplification.
In addition, in the method according to the invention, when the particles are transferred to the surface, the carrier and the surface are guided past one another in strips. Preferably at least one of the surfaces, ie either the carrier or the surface to be printed, is convexly curved, so that the particles are transferred in strips as the movement proceeds. In this way the scattering or diffusion of the image is reduced. The gap through which the electrostatic transfer takes place can be minimized and the simultaneous transfer of multiple colors is made easier. In an advantageous embodiment of the invention, the convexly curved surface is unrolled in relation to the flat carrier and the surface touches the particle layer located on the carrier in a linear manner. This method is particularly advantageous when patterning cylindrical objects such as bottles. However , the carrier can also be designed as a pressure cylinder if a flat surface is to be patterned.

G5 The application of the particles to the electrically conductive carrier can e.g. B. by setting up an electrically conductive pressure plate or roller against a silk screen, a stencil or the like

perforated surfaces take place, on the opposite sides of which lie the pressure particles, which through the openings of the screen that delimit the image onto the surface of the printing plate to be printed. The particles can be removed well by brushing, rubbing or some other mechanical Movement can be pushed through the gaps in the screen. Optionally, the Particles in a liquid solution through the interstices of the screen or through a stencil blown or passed through to adhere to the printing surface. Subsequently there is an electrical potential difference between the carrier and the surface to be printed generated, both surfaces are either electrically conductive or the non-metallic to The surface to be printed is effectively conductive, for example by using a metallic support roller are made. Due to the potential difference, the particles become electrostatic from the surface to be printed attracted and cling to her.

Further, according to the invention, multicolor prints can be easily made. Preferably will formed on the support an image of multicolored particles which are thus aligned with respect to one another are that they represent an image according to the final desired pattern. In advantageous Developments of the invention are thus successively on the carrier to form a multicolored Pattern applied several layers of particles. Optionally, differently colored particles can also be used are electrostatically transferred sequentially from separate carriers.

In an expedient embodiment of the invention for glass objects and particles made of glass frit the glass surface is patterned in the heated state and the pattern is then burned in and heat-treated. The glass object is preferably heated to a temperature at which it becomes electrically conductive, and the electrostatic field is applied to the glass surface and the support.

The fact that the glass surface is hot at the time the frit is applied to the surface makes the surface is sufficiently conductive to electrostatically attract the particles towards the surface. In addition, the fact that the glass surface is hot has an effect on the initial adherence of the particles the glass surface after its transfer to this surface with support, which causes the rebound or the particles jumping off between the two surfaces, d. H. the surface of the glass and the carrier surface, is essentially avoided and thereby sharp and clear coating images arise on the glass surface.

After the particles have been attracted to the surface and after they have adhered to it immediately The particles become the surface in the predetermined pattern or in the desired coating form then sufficiently fused with each other and with the glass surface to create a firm, adhesive, highly resistant, smooth and preferably to form non-particulate coating.

It is of particular advantage if the temperature on the glass surface from the patterning heat applied when the object is formed. Then the melting process can be combined be performed with the normal annealing to which the molded glass article is subjected will. Thus, the final fusion and formation of the coating is achieved at no additional cost at the cost normally incurred in annealing, hardening or other heat treatments of the glass object arise, which is carried out to remove the stresses which normally arise in it during the molding of the object.

Further properties and advantages of the invention go from the description in connection with the Drawings. It shows

F i g. I and 2 a schematic representation for carrying out the method according to the invention,

3 and 4 show a schematic representation of the application of a monochrome pattern on the Carrier by means of screen printing,

F i g. 5 and 6 a schematic representation of the application of a multicolored pattern on the Carrier by means of screen printing,

at) F i g. 7 is a schematic illustration showing the printing a cylindrical object using the carrier according to FIG. 6 explains

F i g. 8 and 9 show a schematic illustration of the application of a multicolored pattern to one Carrier in a modification of the representation according to FIG. 5 and 6,

FIG. 10 is a schematic representation of a cylindrical object which is produced using the methods shown in FIG. 6 carrier shown is printed,
F i g. 11 is an illustration of a cylindrical object printed using the carrier shown in FIG.

The glass articles can have various compositions and shapes. The procedure is particularly suitable for containers made from common soda-lime-silicon glasses or silica glasses applicable. The glasses can also have coloring components, for example titanium oxide, Copper oxide, cobalt or iron oxide, sodium bicromate or the like. The process is just as simple, too on flat glasses, such as B. window glasses, plate glass, rolled or "safety" glass, flat glass or the like, or even to optical glasses, devitrification glasses or the like. Applicable.

All of these glasses show a decrease in resistance or an increase in conductivity with an increase in temperature. The relationship between the conductivity and the temperature of the glass object is in favor of the method of for various reasons, which will be explained in detail below Importance. It has been found that the use of more or less known frits is feasible when the surface of the glass object is at a temperature of more than 260 ° C and below the temperature at which a thermal deformation of the glass object occurs.

A particularly preferred range is between 371 ° C. and the upper limits of the thermal Stability or structural completeness of the shaped glass object, d. H. at about 755 ° C, with the usual glass compositions for containers or at about 925 ° C or even above with certain devitrifiable glass compositions. However, it should be noted that the effect the temperature depends primarily on the temperature of the surface through which the Particles are electrostatically attracted, namely

for reasons that will be explained in more detail below.

In addition, the temperature required in each case is linked to the properties of the hot surface of the object to be deposited or melted in close relationship.

While the greatest economic benefits are achieved by utilizing the residual heat resulting from the formation of the article, consistently good results can be achieved, albeit at additional cost, by reheating the article to the required temperature prior to patterning in accordance with the invention . Since the entire glass forming process, regardless of whether it is by blowing a parison (as in Glass or glass plates is carried out from the outset is a controlled cooling process by which the temperature of the glass is gradually lowered from the temperature at which the glass melts to a temperature which is sufficient. In order to maintain the shape of the object, a considerable amount of residual heat is required. which remains in each molded glass article after the molding cycle is completed, the glass being at a temperature sufficient to maintain the shape of the molded article. If it is container, this temperature may be in the order of about 535-755 ⁰ C, and it is possible in the implementation of the method and from the commercial point of view desirable to exploit this residual heat in the process of the invention.

Since the temperature of the surface to which the particles are to be applied is more important than the total temperature of the object, this surface can be in any way, for example be heated by the action of flames, by the action of radiation, by inductive action.

The thermal adhesion of the particles to the glass is of particular importance in the invention or to each other after being electrostatically attracted to the glass. This thermal cling leads to the substantial elimination of "rebound phenomena" of the particles, i. H. the Tendency of the particles in the electrostatic field to take up the charge on the glass surface or to be removed and again attracted to the wearer, whereupon they again on the glass surface be transmitted. This movement of the particles has the consequence that at least some particles are out their original path will be deflected at an angle and finally to another place on the Glass. This significantly reduces the sharpness of the image, and it becomes a overall background coloration or an overlay is achieved.

It has been found that the particles thermally adhere to one another on the hot glass surface, so that a layer of particles of considerable thickness can be securely attached to the surface without a noteworthy, disruptive rebound occurs. ,.

It is currently still unknown whether this adherence of the particles to the surface and to one another actually occurs due to the melting of the particles or whether it is an incipient one Fusion of the particles with the glass and with each other with relatively small contact surfaces is. DiQ effects of thermal adhesion can, however, result in the increased sharpness of the Images made by electrostatic attraction on 'hot glass surfaces' easily to be observed. When this thermal adhesion is coupled with electrostatic attraction of the particles then an evenly sharp image is achieved. The extent of the total adhesion of the particles on the surface of the glass depends on the composition of the particles of the frit, which is initially applied Electric field potential etc. dependent.

The carrier serves to hold the particles in image form and also serves as the one pole for the electrical Field (the glass surface forms the other pole). The carrier must therefore be electrically conductive and in be able to pick up the particles and in the desired image or shape hold back.

The carrier consists of a metal plate, e.g. B. made of aluminum, anodized aluminum, steel or Copper. Another optional embodiment of a carrier can be a metallic plate which forms an engraving element, in the surface of which recesses or pockets are provided, which with the particles are filled, the remaining part of the surface of the plate being free of such particles is. This engraved plate forms the one pole intended for the electrostatic field and transmits its Charge on the particles, whereby these particles are then carried out of the pockets by the electrostatic field transferred to the hot glass surface. The formation of the pockets in the engraving plate can be on any can be made in any known manner, such as by engraving, etching, and other well known methods Proceedings.

The shape and the overall contour of the carrier can be as desired and as required to carry out the actual transfer process to deposit the particles on the hot Glass surface can be changed. The carrier may, for example, have a shape similar to the general one Corresponds to the shape of the part of the object that is to be decorated, printed or otherwise coated, d. that is, a carrier can be used to hold the particles for attraction by a convex Withhold surface portion or area of a bottle or container, or elsewhere on it while for transferring to a flat glass surface flat carrier can be used. In contrast to this correspondence between the wearer and the object is preferably a flat support for transferring to the convex surface of a Glass container used, the glass container rolled or otherwise across the flat support surface is moved relatively.

The particles according to the invention are frit particles, i. H. finely divided, essentially glassy Particles called "ACL" particles or frits (the abbreviation ACL means Applied Colorant Lettering). These particles are generally referred to as two-phase compositions these compositions are known to be substantially vitreous or vitreous

Have flow phase and a pigment or dye phase. Generally the flow phase closes various opacifiers, e.g. titanium dioxide, and fluxes or materials that are capable of to give the frit properties to achieve the desired low melting point.

The frit generally contains a high proportion of lead oxide and relatively low proportions of silica compared to flint glass compositions and the relative amounts of these ingredients in connection with the finely divided particulate size of the frits as they fuse to a non-particulate, glassy state at temperatures well below the deformation temperature normal glass compositions.

The compositions shown in Tables 1 and 2 are exemplary of such frit compositions. The frit of Table 1 has an essentially blue color, which corresponds to the additive is due to cobalt oxide as a dye, while the composition of Table 2 is a is white in color. Both of these compositions are commercially available.

Table 1

oxide

PbO.
SiO ₂ .
B ₂ O ₁₁
ZrF ₄
ZrO.,.
BaO ".,
TiO ₂ .
Na ₂ O.
Co ₃ O ₄

Table 2

oxide Weight percent Flow phase PbO 53.1
27.3 SiO, 5.9
1.5
2.25
2.15
2.20 B.Ö., 4.0
1 (l BaO 11 "Z _1. F. dye phase TiO, Well, 0 NaF ZrO, ZrO " TiO

The electrical properties of the dye frits, such as those set out in Tables 1 and 2, in particular the total electrical resistance of the frits, have been found to achieve desirable results with frits made in the electrical potentials up to 4 kV have a given total resistance of K) "to K) ¹ ", expressed in ohms / cm.

Are the particles on your carrier in Bihll'orm arranged, the electrostatic potential difference between the carrier and the hot glass surface is created. This electrostatic potential difference does not make it a requirement that either the carrier or the particles or the hot glass-mache must have either a special negative or positive polarity. The procedure is in the Performs equally well in most cases, regardless of the polarity of the hot glass surface. It will

ίο also gets good results when the glass surface is hot is only grounded.

The strength of the electrostatic field, expressed in terms of voltage, can be a preferred Embodiment between 2 and K) kV. However, under special conditions, for example with a minimum gap, with maximum conductivity or the like., voltages of less than 2 kV can be used, and voltages of over 10 kV can be used.

The gap through which the particles should be attracted to the hot glass surface can be a size between a minimum value O (at which the glass surface practically in physical Is in contact with the particles) and of about 6.35 mm. The size of the gap is according to the Operating conditions are changeable and in general

think sufficient to be able to use the respective electrical

Percentage by weight static field strength or voltage one destructive

30 effective arcing to avoid, and is

small enough to cause undue scattering or dispersion of the particles during their attraction to prevent against the hot glass surface. In general, the risk of arcing is around the larger the smaller the gap, although the temperature of the hot glass surface is a certain Has influence on arcing, and the risk of excessive scattering and one The loss of sharpness of the image increases with an increase in the slit.

In Fig. 1, an electrically conductive carrier 30 is off Metal shown which is generally arcuate in shape. whose inner concave surface 31 of the outer convex surface 32 of a bottle 33 is adapted. The bottle 33 is made of glass and was reheated.

The surface 31 of the carrier 30 is etched or engraved by known methods to create a gravure stencil to produce which pockets 35 has. The pockets 35 are filled with frit particles 36 filled, the particles having the composition listed in Tables 1 and 2. To the Gap 37 between the bottle 33 and the arcuate carrier 30 is provided by a high-sparging source 15 and lines 16 and 17 an electrostatic potential difference is applied, and the particles willow transferred from the pockets 35 to the surface 32 of the bottle 33 to be on the convex Surface 32 to produce an image 38. '

The! 'Ritten, for example, have a nominal size from 13 to 2 (> microns and the pockets 35 one Diameter from 0.70 to 0.6 mm and a depth of 0.13 to (), 7ft mm. The gap can have a width between 0.13 and 3.17 mm or canoe at satisfactory attraction to the surface 32 may even be larger. The bags are made by distribution the frit is poured onto the surface of the carrier, and the excess frit has been removed

109 682 99

43.0

32.4

2.5

2.0

2.0

1.3

1.0

5.1

10.6

take from the unholed parts of the top; area 31 removed. At temperatures of about 260 to 559 ° C. and with electric fields of 3.5 to about 5.7 kV, depending on the size of the gap, satisfactory prints are achieved on the hot glass surface 32.

In Fig. 2 the carrier is in the form of a conductive Plate 50 has a flat surface 51 on which several deposits of particles 52 are arranged These particles are arranged in a pattern or image corresponding to a mirror image of the pattern which is on the outside 53 of the bottle or similar glass object 54 is desired. The deposition of the particles 52 on the surface 51 can take place in any desired manner, for example in a screen printing process, a photographic or ferrographic process or in particular one in connection with FIGS. 2 to 11 listed procedures are carried out. Above the Plate 50 is a bottle 54 made of glass, which has a temperature of more than 260 ° C and is rolled across the plate 50 with the bottle exterior 53 in physical contact with it is the exposed top layers of the particles 52.

The unwinding of the bottle represents a composition of movement that is based on a rotating movement in the direction of arrow 57 and a progressive movement of the axis in the direction of arrow 58.

In either case, satisfactory electrostatic transfer of the particles 52 is achieved, too when there is no actual gap between the bottle surface and the particles 52 on the plate 50 is. The voltage is z. B. 5 kV, the glass temperature of 230 to 594 ° C, and the particles are nominally 13 to 26 microns.

While a temperature of at least 260 ° C. is preferably used, it should be pointed out that this temperature can be changed significantly, depending on the particular composition of the glass object, the thermal stability, the particles to be applied to the glass object and the susceptibility of the Particles against thermal adhesion to the surface. In fact, one encounters temperatures normally vary from 370 to 755 ^fi C, with the highest utility of the invention is achieved at 755 ° C, namely by the residual heat of the glass article, resulting from the molding process, is utilized. However, these temperatures only represent the desired embodiment of the invention.

It should also be noted that the temperatures given for the glass articles are actually represent the temperatures of the surface to which the particles are to be applied, and the entire object does not need to be heated. Thus, a localized, limited area the bottle are subjected to heating, for example by induction heat, heating by flames, radiant heat or similar types of heat, especially if the heated part the bottle is then made the pole contact for the electrostatic field.

The degree of thermal adhesion of the particles to the hot surface area is only that Degree of adhesion required to prevent rebounding, and the particles so hold on the surface for a long time until the particles are firmly fused to the surface, preferably through a subsequent heat treatment. Of course, if the surface can have a temperate of 755 ° C or a similar temperature, sufficient heat is transferred to the particles, to actually fuse the particles with each other and with the surface to a sufficient extent, so that the final adhesive coating

xo is formed. This is particularly true where a smooth, enamel-like coating is not required is.

As far as the pattern of the particles is concerned, these particles are given the desired pattern, before they are attracted to the glass surface, and this pattern is made by that the particles are arranged in recesses which determine the pattern (FIG. 1) or in the pattern can be applied to the surface of the carrier (FIG. 2).

It should also be noted that particles of more than one color can be applied at the same time any of the methods shown in the drawings are applied to the glass surface by using the correct means for aligning the particles, before they are exposed to the electrostatic field. These procedures are used in conjunction with the Embodiments of FIGS. 3 to 11 disassembled and explained in more detail. Optionally, consecutive Layers of particles are used to create multicolor effects, with the colors in an order when used successive carriers, each wearing the different colors, are applied.

Although the product to be coated was referred to as glass in the description, it should be noted that that this method can also be applied to devitrified products, which crystals which are held together by a small amount of an amorphous glass structure. The described method is also suitable for printing on objects not made of glass applicable. If the surface of the object to be printed is non-conductive, then for example a metallic support roller or plate can be provided in the area of electrostatic attraction. Examples of particles which can be used in this context are given in U.S. Patents 2,966,429, 3,013,890, 2,955,035, 2,618,551 and 2,638,416 are given. Generally these particles are in different Colors available and can be made by adding pigments or dyes of the desired Coloring can be easily adapted to different colors.

In the case of the FIGS. The embodiment shown in FIGS. 3 to 7 is the application of an image to a Glass object illustrated by screen printing.

3 shows a template 110 which can be made of fine wire 111, for example stainless steel wire, or of a metallic plate or the like, in which small holes are formed by punching or similar processes. The stencil 110 has openings 113 which correspond to the final printed image or a mirror image of the final image, as well as closed areas 112 and is produced, for example, by a photographic method in a known manner.

The finished and developed stencil 110 is placed on a support 115 which has a flat surface 116 which abuts the underside of the undeveloped or non-apertured portions of the stencil 110 and bridges the developed image delimiting openings 113 therein.

Carrier 115 is electrically conductive, preferably metallic, although non-metallic carriers that are coated, plated, or otherwise bonded with electrically conductive material can also be used, as well as non-metallic carriers capable of conducting a sufficient amount of current to conduct a pole to form for the electric field. »5

The particles 117 are then applied to the stencil, the size of the particles being matched to the openings of the stencil so that the particles do not simply fall through the stencil onto the surface 116 of the carrier. ao

A brush 118 or other means is then passed across the surface of the stencil in order to mechanically press the particles 117 through the stencil 110 or, more precisely, through the opening 113 onto the surface 116 of the carrier 115. While this transfer of particles through aperture 113 can be accomplished in a number of ways, the use of brush 119 has significant advantages. The brush forms a safe means of forcing the particles through: through the opening 113, the functions of the brush can easily be automated, and the action of abrasive brushing which is exerted on the particles and applies them to the plate is triboelectric Adhesion of the particles to one another and to the surface 116 , which helps maintain a clearly defined and coherent mass 120 of particles from the surface 116 , as shown in FIG. 4 is shown. This coherent mass 120 corresponds substantially identically to the image aperture 113 in the stencil 110 and it has been found that complex images, even those involving halftone photographic representations, can be accurately and flawlessly reproduced in the layer 120.

In the event that the final printed image is to be monochrome, the carrier 115 of FIG. 4 can continue to be used immediately.

However, since one of the most desirable features of the invention is the application of a multicolored image to the surface to be printed, in a preferred form of the invention the support 115 is subjected to a subsequent operation which is illustrated in FIG. 5 is shown. In a particular example, the carrier 115, which is composed of continuous masses 120 of particles of a coloring, e.g. B. blue, has been provided with the underside of a second template 122 to the plant, which is substantially the same as the template 110 and has wires 123, an opening 125 and closed surfaces 124 .

The particles 127 of a different color, e.g. B. white, are then pushed through the opening 125 onto the surface 116 in the area of the zones 126 , for example by a brush 118, so that on both sides of the mass 120 the second assembled mass 128 of particles in FIG. 6 is created.

When the carrier 115 is brought into contact with the underside of the stencil 122, the previously applied, assembled and aligned particles of the mass 120 fill the spaces in the wire 123 and prevent the passage of particles of the layer 127 through the opening 125 in areas where to which the particles of the mass 120 have already been applied beforehand. It follows that the thickness of the stencils 110 and 122 are the same.

It is thus possible to provide particles of different colors and characteristics on the surface 116 of the carrier 115 in order to subsequently be electrostatically attracted at the same time to a surface to be printed.

In Fig. .7 has the object to be printed 130, e.g. B. a glass bottle, a cylindrical cross-section and is connected by a line 131 to a high-voltage source 133 , the other side of which is connected by a line 132 to the conductive carrier 115 . By applying a relatively high voltage, e.g. B. on the order of 1 to 20 kV, at the space 135 between the object 130 and the carrier 115 , the particles of the masses 120 and 128 are attracted from the surface 116 of the carrier 115 to the surface 134 of the object 130. This electrostatic attraction arises due to the fact that the particles on the carrier accept the charge of the carrier and are attracted to the surface 134 of the object 130 due to the opposite polarity of the surface.

The object is preferably as shown in FIG. 7 with its surface 134 in contact with the particles of the masses 120, 128, so that a minimal gap is formed over which the attraction takes place due to the electrostatic field. However, the relative spacing of surfaces 116 and 134 can be adjusted to provide gaps up to 6.35 mm. It should also be noted that the object 130 is rolled or otherwise moved relative to the carrier 115 and the particles of the masses 120, 128 located thereon, this movement taking place by rolling the object 130 in the direction of arrow 136 with respect to the carrier 115 and the Axis of the object is moved laterally in the direction of arrow 137 . If a flat top 134 is to be printed, the surface 116 of the carrier can be convex.

In the F i g. 8 and 9, a modification of this basic method is shown, wherein the particles of the mass 120 in a manner analogous to that in FIGS. 3 and 4 have been applied to the surface 116 of the carrier 115 , but using a second stencil 140 with a perpendicular dimension or thickness which is appreciably greater than the thickness of the stencil 110 or 122.

The relationship between these templates can be changed significantly. As the thickness of the stencil Depending on the strength of the wire used, the stencil strengths will usually be determined by the designation of the size or diameter of the wire used. In one

In a particular example, three-color prints are produced on substrates by using a first color (corresponding to the mass 120) which is applied through a wire screen of 0.75 × 0.075 mm mesh size and a wire diameter of 0.04 mm '; then a second color is applied through a second stencil 140 made of a wire screen, about 0.09X0.09 mm mesh size and a wire diameter of 0.05 mm. A third color is then applied with a third stencil, namely a wire screen with a mesh size of approximately 0.1 × 0.1 mm and a wire diameter of 0.058 mm.

Thus, wire 141 of stencil 140 is slightly stronger than wire 123 of stencil 122, and opening 142 is of a size sufficient to encompass at least all portions of the preformed and assembled image of mass 120 . Then a particle layer 143 on top of the template 140 is pushed through the wire 141 by means of a brush 118 , the particles of the layer 143 forming an image 145 which surrounds the preformed image of the mass 120 on the periphery and covers it as best from Fig. 9 can be seen. The image formed by the particles of the masses 120 and 145 on the surface 116 of the carrier 115 can easily be applied to an article 130 by the method described in connection with FIG. 7.

10 shows the pattern produced by means of the carrier coated according to FIGS. 3 to 7, which appears two-colored in both viewing directions 146 and 147 , with the pattern being viewed in a mirror-inverted manner in viewing direction 147.

In FIG. 11, on the other hand, the pattern is represented by means of the method shown in FIG. 8 and 9, the same two-color pattern being seen in the viewing direction 146 as in FIG. 10, while in the viewing direction 147 only a single-color image is visible.

Thus, a view of the pattern is reversed when using the method of FIG 8 and 9 avoided. In certain circumstances it may be desirable to follow the procedure according to F i g. 8 and 9 compared to the method according to FIG. 3 to 7 are preferable, but both methods are applicable within the scope of the invention.

The methods described for forming colored images by sequentially applying Particles can also be used to sequentially create particles of the same or substantially the same Color, but different structure, particle size c or other physical properties to achieve different effects. Similarly, separate carriers, each bearing a portion of a complete image, can be sequential can be used to create a finished multicolored picture to manufacture.

In an embodiment according to FIG. 3 using a template 110 of 0.075 '0.075 mm mesh size with a wire diameter of 0.04 mm over a cold-rolled Fhißstahlplatten 3.17 mm thick as a carrier 115 , blue particles of the following composition were through the sieve 110 through the surface 116 of the support 115 is brushed:

oxide Weight percent PbO 43.0
32.4 SiO ₂ 2.5
2.0 B, O, 2.0
1.3 ZrF. 1.0
5.1
10.6 ZnO ₂ BaO TiO ₂ Na ₂ O Co ₃ O ₄

Next, the template 122, which had an enlarged opening to determine the pattern, but was otherwise identical to the template 110 , was used to apply a second color to border the first image with the mass 120 , the second color being white and had the following composition:

oxide Weight percent Flow phase 25th PbO 53.1 SiO ₂ 27.3 B., 0., 5.9
1.5
2.25
2.15
2.20 BäÖ 4.0
1.6 11% dye phase 30th TiO ₂ Well, 0 NaF ZrO, ZrO TiO.,

60

The particles which formed both the blue image and the white surrounding coloration of the mass 128 were nominally 0.3-0.6 mm.

A glass object having a temperature of 538 to 595 ° C was then placed on the inclined Carrier unrolled freely downwards with an electrical potential difference of 6 kV between object and carrier. Satisfactory prints were obtained.

Further good prints were also obtained by producing the image according to the composition 120 on the surface of the carrier 115 by using a stencil 110 of 0.75 × 0.75 mm mesh size with a wire diameter of 0.04 mm, then the image under a second stencil 140 placed on the carrier 115 and then white particles of the above-mentioned composition were brushed through the stencil 140 . The template 140 had a mesh size of 0.09 × 0.09 mm with a wire diameter of 0.05 mm, so that the particle image 145 framed the image according to the mass 120 as shown in FIG.

Claims (6)

Patent claims: 1. Electrostatic process for producing single or multi-colored patterns, in particular on Glass objects, in which electrically chargeable particles on a carrier in to the pattern ■ • 'applied in mirror image form and then by means of an electrostatic field are transferred to the surface to be printed, whereupon the pattern is fixed on the surface, d u rc h indicated that the particles through per se known method applied directly to an electrically conductive carrier by Applying the electrostatic field and charged with a movement in which the surface and the carrier are led past each other in strips, are transferred to the surface. 2. The method according to claim 1, characterized in that the convex curved surface is unrolled in relation to the flat carrier and the surface is the particle layer located on the carrier each touched linearly. 3. The method according to claim 1 or 2, characterized in that one after the other on the carrier several layers of particles are applied to form a multicolored pattern. 4. The method according to any one of claims 1 to 3, wherein the surface is the surface to be patterned of a glass object and the particles consist of glass frit, characterized in that that the glass surface is patterned in the heated state and the pattern is then burned in and is heat remunerated. 5. The method according to claim 4, characterized in that the glass object on a Temperature is heated in which it becomes electrically conductive and the electrostatic field at the Glass surface and the carrier is applied. 6. The method according to claim 5, characterized in that the glass object when patterning has a temperature of at least 260 ° C, which is different from that when the glass object is molded supplied heat originates. For this 2 blue drawings 109 682/99