DE2750370A1 - CONTINUOUS PROCESS FOR ELECTROSTATICALLY COATING AN OBJECT WITH PULVERIZED MATERIAL - Google Patents

Description

HOFFMANN · EITLE & PARTNER 0 7 C η q 7 _n

PATENTANWÄLTE LI 0 UJ / (J DR. ING. E. HOFFMANN (1930-197) ■ DIPl. -I NG. W.EITLE DR. RER. NAT. K. HOFFMANN ■ Dl Pl.-ING. W. IEH N

DIPL.-ING. K. FOCHSLE DR. RER. NAT. B. HANSEN ARABELIASTRASSE 4 (STERN HAUS) D-8000 MO NCH EN 81 TELEPHONE (089) 911087 TELEX 05-29619 (PATHE)

The invention relates to a continuous process for the electrostatic coating of an object with pulverized material and, in particular, relates to a continuous process for the electrostatic coating of an essentially axially symmetrical object with pulverized material, which is characterized in that the object is transported by means of a conveyor into an electrostatic coating chamber, which is provided with plate electrodes on both sides of the chamber walls for silent discharge, that electrically charged powdered material is introduced into the chamber, that the electrostatic coating of the article with the powdered material is carried out by means of the silent discharge from the electrodes and that the excess powdered material is removed from the specific parts of the article by means of suction.

The invention further relates to an apparatus for the continuous electrostatic coating of a substantially axially symmetrical article with powdered synthetic resin, which is characterized in that firstly an electrostatic coating chamber where the powdered synthetic resin is applied to the surface of the article, the article at a temperature is kept below the melting point of the resin and the article has been placed in the chamber by means of a holding device and (ii) a device for removing excess powdered resin from specific parts of the article by suction in order to obtain the electrostatic coating of only the desired parts.

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The invention relates to a continuous process for the electrostatic loading of glass bottles and other axially symmetrical ones Articles containing powdered material and an apparatus for carrying out this process. In particular, relates the invention relates to a continuous process for the electrostatic coating of an axially symmetrical object with powdered synthetic resin and an apparatus for carrying out this method wherein the .Verfahren characterized is that the electrostatic coating with powdered synthetic resin is achieved on the surface of an axially symmetrical object, the object at a temperature below the melting point of the powdered resin, and the excess of the powdered synthetic Resin (hereinafter referred to as "excess powder") is removed from desired parts and then that with the pulverized Resin coated article is heated to form a resin film on the surface of the axially symmetric article will.

Lately the aim has been to make a film of a synthetic To apply resin to glass bottles for carbonated beverages and the like to avoid breaking the glass bottles during handling and / or because of the risk of excessive internal pressure in the bottles as a result of exposure to sunlight. According to the usual electrostatic coating process, it is usually necessary to use the glass bottles to a temperature above the melting point of the powdered synthetic resin, since the glass bottle is an electric Isolator is. That is, common electrostatic coating processes include preheating a glass bottle to a temperature above the melting point of the resin To reduce the electrical resistance of the glass, further electrostatic coating with powdered synthetic resin the preheated glass surface and then post-heating the resin-coated glass bottle around a resin film on the surface to train the glass bottle. According to this usual procedure However, it is mostly impossible to powder excess

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Resin adhering to unwanted parts, as the glass bottle has been preheated. To prevent being powdered If resin adheres to the undesired parts (for example, the bottle mouth), it is suggested that electrostatic plating by using a gas stream in the vicinity of the opening of the bottle to carry out the opening of the Cover bottle. However, with this method it is essentially impossible to cover the entire opening of the bottle and as a result, powdered resin often adheres to the opening of the bottle, which is closed by means of a cap, so that various serious problems such as inaccurate closure or open by means of the cap and the formation of a resin film in the contents of the bottle. Powdered material also sticks Resin also on the holding arms or jigs of the holding device and as a result of the accumulated and hardened Resin, the operation of the device must be interrupted in the meantime. In addition to the disadvantages mentioned above, the thickness of the resin film on the top part of the bottle is uneven and thin, causing cracking and peeling of the resin film during a washing process or the transport of the resin-coated bottles can be done. These problems are for return bottles particularly difficult as the life of the glass bottles is reduced. Next will increase the economic value of the glass bottles required an even coating with the resin film with a uniform thickness. The usual procedure to one Electrostatic coating of preheated bottles, however, leads to the disadvantages mentioned above and does not satisfy them Requirements.

The object of the invention is therefore to avoid the above-mentioned disadvantages of the usual process and a continuous process for the electrostatic coating of a substantially axially symmetrical object with pulverized material achieve, which is characterized in that the object by means of a conveyor holding device in an electrostatic coating chamber with electrodes on both sides of the chamber walls that electrically precharged powder is introduced

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Material is introduced into the chamber that the electrostatic coating of the object with the powdered material is carried out by means of a silent discharge from the electrodes, and that the excess powdered material of special Parts of the object is removed by suction. It is further. The object of the invention is a device for performing the to provide electrostatic coating of a substantially axially symmetrical object with powdered material, which (i) has an electrostatic coating chamber where powdered synthetic resin is applied to the surface of a non-preheated Object is applied, which is kept at a temperature below the melting point of the resin, wherein the article has been placed in the chamber by means of a conveyor fixture, and that (ii) a removal device the excess powdered resin is removed from specific parts of the object by suction. By means of the device According to the invention, powdered resin is electrostatically coated on desired parts in just such a manner is applied so that a powdered resin layer of uniform thickness and clean definition is formed. The resin-coated The article is then heated to give a synthetic resin coated article of high durability create. The device according to the invention thus provides a resin-coated article with a high degree of efficiency, which has a high economic value.

Embodiments of the invention are shown in the drawing and are described in more detail below. Show it:

F i g. 1 shows a view of the device according to the invention

for electrostatic coating of a glass bottle

with powdered material; F i g. FIG. 2 is a sectional view of an upper suction gap in FIG

Device for removing excess powder; F i g. 3 is a sectional view of a lower suction gap in FIG

Device for removing the excess powder;

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F i g. 4 is a plan view of FIG. 2; F i g. Figure 5 is a bottom view of Figure 3; F i g. 6 shows another embodiment of the upper suction gap

to remove the excess powder, as in Fig. 2

shown;
F i g. 7 shows another embodiment of the lower suction gap

to remove the excess powder as in FIG. 3

shown;
F i g. 8 shows another embodiment of the upper suction gap

of Fig. 2 with a crimping part; and F i g. 9 shows another embodiment of the lower suction gap

of Fig. 3 with a crimping part.

As shown in the accompanying drawing, the device comprises for carrying out the method according to the invention firstly an electrostatic coating chamber, where pulverized synthetic resin is applied to the surface of a glass bottle for coating, which is fed into the chamber by means of a Collet of a movable holding device is conveyed and, secondly, a device for removing the excess powder from the special parts, such as the opening and / or the bottom of the bottle, that should not be coated.

As can be seen in Fig. 1, glass bottles 1 are being prepared for electrostatic coating one after the other Bottle feeder (not shown) supplied. The opening the bottle 1 is by a collet 3 of a chain conveyor 2 and the bottle 1 held by the device 2 is inserted into the inlet port of an electrostatic coating chamber 5 promoted by means of the holding device 2. The chamber consists of a long narrow housing 6 (a part is shown in Fig. 1) with an outlet located at the distal end. The bottle 1 held by the holding device 2 is electrostatically coated with powdered synthetic resin as it passes through the chamber 5. The upper part the housing 6 is opened by means of a slot in order to allow the collet 3 of the holding device 2 to pass through.

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The housing 6 of the chamber 5 has suction parts 7 on both sides of the upper part of the housing, further plate electrodes 8 for one silent discharge on both sides of the case and a feeder 9 for powdered resin at the bottom of the case, which introduces electrically precharged powdered resin into the case 6. The powdered resin feeder 9 is preferable arranged at suitable sections depending on the length of the housing 6.

The powdered resin feeder 9 includes an electric one Pre-charging device 11, where the powdered resin by means of a Corona discharge, a contact charge or another suitable method is precharged so that the polarity of the Resin is the same as that of the plate electrode for silent discharge, and then feeds the pre-charged powdered resin into the case 6 by means of an air stream. The precharged powdered resin introduced into the case 6 in this way becomes electrostatic on the glass bottle 1 passing through the case 6 is moved by the action of an electric field between the plate electrodes 8 for a silent discharge and of the glass bottle 1 was erected so as to have a good solid layer of charged powdered resin on the surface to train the glass bottle. An electric current or voltage of the plate electrodes 8 for silent discharge and the precharge device 11 is regulated by means of a suitable electrical control 12. As in the disclosed Japanese Patent Application No. 51-8347, the plate electrode 8 for silent discharge consists of parallel wire electrodes, which are embedded in insulating panels. The silent discharge is created on the surface of the plates by applying an alternating voltage between the parallel wire electrodes and a small discharge current and an electric field created by the Plates flowing to the glass bottle is achieved by superimposing a direct current voltage on the alternating current voltage, whereby powdered resin is prevented from adhering to the surface of the plates.

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The suction part 7 has a suction chamber 15 arranged on both sides of the upper part of the housing 6, a suction inlet on the inner side of the suction chamber 15 and an outlet 17 the outer side of the suction chamber 15, an outlet 17 with a suitable dust collector and a suction fan, not shown is connected by means of a suction line 18. The suckers accordingly prevent powdered resin from falling out of the slit-like one opening of the housing 6 exits and collects the powdered resin, which does not adhere to the surface of the bottle, for a new use.

The case 6 may additionally have a powdered resin feeder, which is a precharge device, on its sides and has the same function as the powdered resin feeder 9 mentioned above. The additional powdered resin feed feeds resin powder to the glass bottle from the lateral direction and is pulverized for making extra thicker Resin layers on a specific part of the bottle and to adjust the thickness of the layer depending on the shape of the Bottle suitable.

The electrostatic coating chamber 5 has a suction slot 21 to remove the "excess powder" in such a way that powder from special parts, such as the top and / or removed from the bottom of the bottle. As can be seen in FIGS. 2 to 5, the suction gap device 21 comprises suction gaps 22 and 23, which are arranged near the top and bottom of the bottle, the suction gaps 22 and 23 with suitable dust collectors and a suction fan to remove "excess powder" from special parts and that Collect resin powder. When the bottle 1 electrostatically coated with powdered resin in the chamber 5 to the suction gap device 21 is conveyed, the collet 3 of the holding device 2 is rotated by means of suitable devices, see above that the powder is removed from the specific parts including the head and / or the bottom.

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As can be seen in FIGS. 6 and 7, the strength of the suction force can be controlled in a manner that allows suction efficiency depending on the part and shape of the bottle by the suction port in upper and lower columns 22 'and 23 * the "excess powder" - Removal device 21 'is subdivided by means of partial plates 24 and 25 and in the draft regulations 26 to 31 in each Suction opening are provided. Furthermore, the sub-plates 24 and 25 can preferably protrude a little from the plane of the suction opening so that that they act as a spacer between the suction gaps and the clamp of the holding device, the upper and the lower part serve the bottle to keep a suitable gap between them.

In FIG. 6, the suction rate 32 and 33 is kept relatively high in order to completely remove the powder from the collet 3 of the holding device 2 to remove while the suction rate 34 to create a sharp boundary 35 at the top of the powdered resin layer should be adjusted depending on the amount of electric charge and the adhesive force of the powdered resin layer, however, it is generally relatively slower compared to suction rates 32 and 33. The same is true with regard to the Suction rates 37 and 39 to create a sharp boundary 36 and the suction rate 38 to completely remove the excess powder from the middle part of the floor as shown in FIG. That is, the suction rates 37 and 39 are relatively lower, while the suction rate 38 is relatively high. If desired, the "excess powder" removal system according to the invention also on other parts different from the opening and the bottom of the bottles be attached.

It can be seen from FIGS. 8 and 9 that the suction slots 22 and 23, if desired, crimp parts 40 and 41 made of elastic material, such as rubber to facilitate removal of the "excess powder". The suction slots 22 and 23 can also be provided with an elastic element such as a spring in such a way that a permanent close contact between the crimped part and the collet or

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special parts of the bottle from which "excess powder" is removed should be maintained.

As mentioned above, according to the invention, powdered resin is electrically applied to the surface of a glass bottle in such a bottle Applied in such a way that a solid powdered resin layer of uniform thickness is formed, which is well charged and adhered to the Glass surface adheres and with "excess powder" being satisfactory is removed, further establishing a sharp boundary line. The bottle coated with powdered resin is then post-heated to form a solid resin film of uniform thickness on the bottle surface, thereby increasing the life the bottle and its economic value is increased. Next is according to the invention "excess powder" on the Holding device completely removed so that the device can operate continuously over a long period of time, whereby the production speed is very high.

The present invention has been made in view of the case of electrostatically coating a glass bottle with powdered Resin, but it should be noted that the present invention also applies to other substantially axially symmetrical objects such as cones and the like can be used. Further, in addition to the synthetic resin, other inorganic powders such as enamel frit powder can be used and the like can be used to carry out the method according to the invention.

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Claims (8)

HOFFMANN · EITLE Oc PARTNER - PATENTANWÄLTE Z / 5 U 3 7 Q OR. ING. E. HOFFMANN (1930-1976) ■ DIPL.-ING. W.EITLE DR. RER. NAT. K. HOFFMANN DIPL.-ING. W. LEHN DIPL.-ING. K. FOCHSLE DR. RER. NAT. B. HANSEN ARABEILASTRASSE 4 (STERNHAUS) · D-SOOO MÖNCHEN 81 · TELEFON (089) 911087 ■ TELEX 05-29619 (PATHE) Onoda Cement Company Limited, Onoda, Japan Continuous process for the electrostatic coating of a Object with powdered material Claims Wed Continuous process for electrostatic coating an object with pulverized material, characterized in that the object (1) by means of a holding device (2) in an electrostatic coating chamber (5) with plate electrodes (8) for a silent discharge on both sides of the chamber walls is promoted that Electrically charged pulverized material is supplied to the chamber (5) that the object electrostatically with the pulverized Material is coated by means of the silent discharge of the electrodes (8) and that the excess powder of special parts the object is removed by suction. 2. Continuous process according to claim 1, characterized in that that the surface of the object is at a temperature below the melting point of the pulverized material is held. 609819/1018 3. Continuous process according to claim 1 or 2, characterized in that the object (1) is continuously with the powdered material is electrostatically coated as it passes lengthways through a long narrow electrostatic coating chamber (5) is moved. 4. Device for continuous electrostatic coating a powdered synthetic resin article characterized in that (i) an electrostatic coating chamber (5) where the powdered synthetic resin is applied to the surface of the object (1) for coating, that the object is kept at a temperature below the melting point of the resin, the object by means of a holding device (2) was conveyed into the chamber (5), and that (ii) a device for removing the excess of the pulverized Resin from particular parts of the object by means of suction of the electrostatic coating of the desired parts is provided. 5. Apparatus according to claim 4, characterized in that the electrostatic coating chamber (5) is a long narrow one Housing (6) through which the object can pass that on both sides of the housing (6) plate electrodes (8) for a silent discharge are arranged that a suction part (15) on upper part of the housing (6) is provided and that a powdered resin feeder (9) with an electric charger (11) is provided to pass powdered resin through the soil and / or feed the sides of the housing (6). 6. Apparatus according to claim 4 or 5, characterized in that the device for removing the excess pulverized Resin suction gap openings (22,22 ', 23, 23'), which in the Are located near the particular parts of the article from which the excess powdered resin is to be removed. 7. Apparatus according to claim 6, characterized in that the suction gap openings not only in the vicinity of the special parts 809819/1018 of the object but also on the clamp of the holding device are provided. 8th . Device according to claim 6, characterized in that the suction gap openings are squeezing devices made of elastic material, such as rubber to facilitate removal of the excess powdered resin. 609819/1018