Abstract:
The present invention relates to a method and device for manufacturing coated sleeves, whereby the sleeve is positioned vertically and held stationary, while a feed pipe is introduced from below, by vertical displacement, concentrically into the sleeve. Also from below, an excess of fluid is supplied under pressure, through the feed pipe. The fluid is allowed to emanate from an upper end outlet of the feed pipe and allowed to flow by gravity in the small gap which is formed between the feed pipe and the internal walls of the sleeve. The internal walls of the sleeve are thereby coated with the fluid, while at the same time, the coating of the outside of the sleeve is prevented. The invention also relates to a writing pen comprising a coated sleeve.

Description:
TECHNICAL FIELD 
     The present invention relates to a method of manufacturing coated sleeves, a device for its execution and products comprising sleeves coated according to the present method. 
     BACKGROUND OF THE INVENTION 
     Many office and writing products, food packaging etc are manufactured from plastic or metal or combinations of these materials. With the increase in environmental awareness over a number of years, there is a desire to be able to use instead renewable raw material containing for example cellulose, such as cardboard and paper, for example in pens, sleeves for glue sticks, containers for correction fluid, sleeves for various foodstuffs etc. One problem, however, is that cardboard absorbs and/or lets through liquid if it is not protected against the liquid or treated in a suitable manner. It is relatively common to provide pens for example with an outer sleeve of cardboard, in which however the inner ink container is still of plastic or metal. To the eye this perhaps appears to be environmentally friendly, but is not so in practice. Other attempts have been made to utilize cardboard or paper by coating a sheet of paper with a liquid-proofing plastic layer, the sheet then being wound round several turns in the form of a sleeve, so that a cylindrical space is formed. A disadvantage of this method is that the material in the sleeve becomes impossible to recycle. It would in fact also be possible to dip a cardboard tube into a fluid, which on drying/solidifying produced a liquid-proofing film. The problem then is that it is difficult to apply text and other print to the outside of the sleeve. As far as the inventor knows, no method has been developed for the manufacture of cardboard sleeves or similar items which are coated on the inside only with a liquid-proofing film of a type other than plastic. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The object of the present invention is to remedy the above complex problems and provide sleeves of renewable raw materials such as cardboard, coated with a liquid-proofing film on the inside which is not composed of plastic or metal, intended to be capable of being used in marker pens, glue sticks and other similar office and writing products and as food packaging. 
     This object is achieved according to an aspect of the invention by a method and a device characterized by the characterizing part of the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following description of a preferred embodiment, reference will be made to the enclosed drawings, of which 
     FIG. 1 shows a sectional view of the device for coating sleeves according to the invention, 
     FIG. 2 shows a partial view of the device according to FIG. 1 from the side, 
     FIG. 3 shows a partial view of the device according to FIG. 1 from above, 
     FIG. 4 shows a detailed view of the coating of sleeves on the inside, 
     FIG. 5 shows a detailed cut away view from the side of a lower holding device forming part of the device according to FIG. 1, 
     FIG. 6 shows an example of a product which comprises sleeves manufactured using the device according to FIG.  1  and 
     FIG. 7 shows another example of a product. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     The device according to the invention which is shown in the drawings generally has the reference number  10 . The device comprises a stand or frame  12 . Disposes in the frame is a tank or container  14 , which is filled to a certain level with a coating fluid. Disposed in the tank  14  are a pump  16  and a heating device, for example heating coils with hot water. A cylinder  18  is fitted under the tank  14  and oriented vertically. The piston rod  20  of the cylinder  18  runs through a bushing  22  into the tank and a distance into the tank, the bushing  22  being fitted with suitable seals. Affixed to the piston rod  20  at its end is a pipe  24 , henceforth called the feed pipe, which pipe runs concentric to the piston rod  20 . Fitted to the lower part of the feed pipe is a pipe connection  26 , which communicates via a flexible hose  28  with the outlet of the pump  16 . The length of the feed pipe  24  and the stroke length of the cylinder  18  are matched so that the upper end of the pipe  24  is positioned at a distance under the surface of the fluid when the piston  20  is in its lower end position and the upper end of the pipe  24  is positioned at a distance above the upper edge of the tank when the piston  20  is in its upper end position. The function and length adjustment of the device will be described in detail below. 
     Arranged on the top side of the stand is a holding device  30 . On this, a lower holding device  32  in the form of a ring with a through passage  33  is arranged concentrically to the feed pipe  24 , the diameter of which ring is somewhat larger than the diameter of the pipe, FIG.  5 . The passage of the ring is formed tapering seen from below and with a level upper side  35 . The ring  32  is also equipped with channels  34  or recesses for heating coils, cooling coils or the like for heating, cooling or maintaining the ring at a constant temperature. The ring is preferably also equipped with a temperature sensor  37 . Fitted to the holding device are two guides  36 , FIG. 4, in the form of two shafts, which guides are directed vertically upwards and run parallel to the feed pipe  24 . Attached to the upper ends of the guides  36  is a bracket  38 . Arranged on the bracket  38  is a cylinder  40 , the piston rod  42  of which is directed vertically downwards and is concentric to the feed pipe  24 . A second bracket  44  is arranged on the end of the piston rod  42 , which bracket  44  is disposed slidably in relation to the guides  36 . Affixed to the second bracket  44  is a sealing device  46 . The sealing device  46  is formed with a space  48  open downwards with a circular edge and tapering when seen from the edge, the side walls of the space  48  sloping in somewhat towards the middle of the space, where they pass into an outwardly directed elevation  50 . 
     Arranged on the holding device  30  and closely adjacent to the ring  32  is a fixing device  52 . In the embodiment shown, the fixing device  52  is formed as a vertical V-block. A horizontally oriented cylinder  54  is disposed on the holding device on the opposite side to the fixing device  52  as seen from the ring  32 . Fitted to the end of the piston  56  of the cylinder  54  is a pushing device  58  in the form of a vertical V-block in the embodiment shown. The piston rod  56  of the cylinder is directed towards the support and its centre axis C I  cuts the centre line C II  which runs perpendicularly through the pipe and the ring. The cylinder  54  has a stroke length such that the pushing device  58  can be oriented and immediately in front of/above the ring  32 . A supporting device  60 , FIG. 3, in the form of a spring wire is fitted to the holding device  30 . The spring wire  60  extends in front of the pushing device  58 . Arranged above the pushing device  58 , when this is in its rearmost position and the rearmost position of the piston rod, is a feed device  62 . In the embodiment shown this comprises a vertical pipe  64 . The upper end of the pipe is suitably connected to a magazine, which is not shown. The feed device also comprises a vertical arm  66 , referred to below as a tilting arm, which is affixed pivotedly at its centre. Disposed in the ends of the tilting arm  66  are two heels  68 , where the upper heel can extend via an opening  70  in the pipe into this and the lower heel can extend below and in front of the end of the feed pipe. A pneumatic cylinder  72  is disposed at one end of the tilting arm  66 . 
     A second, horizontally oriented cylinder  74 , FIG. 3, with a piston rod  76  is also arranged on the holding device. The cylinder  74  is positioned so that the centre line C III  of the piston rod cuts the centre line of the ring  32 . A gripping device  78  is fitted to the end of the piston rod  76 . Affixed to the gripping device  78  is a turning device  80 , which facilitates turning of the gripping device 180° around the piston rod centre line. The cylinder  74  has a stroke length such that the gripping device  78  can be conveyed up to and above the ring. A discharge station is arranged by the side of the holding device. All cylinders include are connected to an air source and fitted with suitable breakers and contacts for control of the cylinders. The entire device is controlled by a suitable control system of a conventional nature, which will not be described in further detail. 
     The device functions as follows. The tank  14  is filled with a suitable fluid with which the sleeves are to be coated on the inside, and if required the heating device in the tank is activated depending on the type of fluid. The magazine and feed pipe  64  are filled with sleeves H, with the lowest sleeve lying close to the lower heel  68  of the tilting arm. The ring  32  and the sealing device  46  are heated, cooled or temperature-controlled all as required. When the device is activated, a signal is first given to the pneumatic cylinder  72 , which controls the tilting arm  66 , at which this is turned a little around its axis of rotation. The lower heel  68  is then moved away from the feed pipe  64  and lets a sleeve drop down at the same time as the upper heel is carried into the pipe and prevents further sleeves from tumbling down. A short time later, the cylinder is deactivated and the tilting arm resumes its original position with the lower heel in the pipe, thanks to the tension spring  72 . The sleeve which was stopped previously then drops down on the heel to await the next cycle. The sleeve which has been released falls down towards the table of the holding device  30  and ends up in front of the pushing device V-block  58 , which is in its rearmost position. The sleeve is prevented from falling over by the spring wire  60  of the supporting device. The pushing device is then activated and pushes the sleeve towards the V-block of the fixing device  52 , at which the lower part of the sleeve is arranged concentrically on the level top side  35  of the ring  32 . The cylinder  40  for the sealing device  46  is then activated, which moves down and bears on the upper edge of the sleeve with its tapered space, FIG.  4 . Following this, the cylinder  18  for the feed pipe  24  and the pump  16  in the tank is activated. The feed pipe  24  is now pushed up through the ring  32  and up into the sleeve at the same time as the pump pumps the fluid up through the pipe  24  and through the pipe opening, and further up towards the sealing device  46 . Due to the shape of the sealing device  46  with the point  50  directed downwards in the centre, the fluid is made to flow out from the centre of the sealing device  46  towards the edges on the sealing device and the sleeve. The feed pipe  24  is formed with a diameter which is somewhat smaller thank the inner diameter of the sleeve, so that a gap is formed between the sleeve H and the pipe  24  and the excess fluid flows down there while covering the inside of the sleeve and finally through the ring and back to the tank. When the pipe has reached almost up to the sealing device  46 , the pump is stopped and the pipe is retracted, at which the remaining quantity of superfluous fluid runs down into the tank. A certain period now ensues when the sleeve is held in this position to permit some degree of drying/solidification of the fluid. During the entire period in which the fluid is supplied, and during the entire drainage time, the ring  32  and the sealing device  46  prevent the fluid from passing or even coming into contact with the edges of the sleeve, to which contamination of the outside of the sleeve with fluid is also prevented. 
     The cylinder  74  with the gripping device  78  than moves in and grips the sleeve at the same time as the cylinder  40  of the sealing device  46  lifts this a short distance. The gripping device  78  draws the sleeve out a short distance and turns this 180° around a horizontal axis and holds the sleeve in this position for a certain period longer. This operation is carried out so that the fluid shall not collect during drying/solidification in the lower part of the sleeve and solidify there to form an annular edge on the inside of the sleeve&#39;s lower edge. When the drying time is finished, the griping device removes the sleeve and releases it in a suitable position for further treatment. Then a new cycle begins in that a new sleeve is let down from the feed tube  64 . 
     The fluid which is deposited on the inside can be of various conceivable types such as wax, paraffin or mixtures of these, water-based lacquer or similar. The important thing in this respect is that the fluid gives rise to a diffusion-proof film on the inside of the sleeve to act so that the liquids with which the sleeve will then be filled are prevented from leaking out in the vapour or liquid phase through the sleeve walls. A sleeve manufactured according to the above method and device has a number of application areas. 
     An example is shown in FIG. 6, in which the sleeve is used as a body for marker pens  80  and the like filled with colouring liquid. These are often constructed so that a body  82  of absorbent, tampon-like material is arranged in the sleeve, ink or another dye is put into the sleeve and absorbed by the body and its ends are sealed with plugs  84 ,  86 , one plug being fitted with a writing tip  88  which extends into the body. 
     Another example is shown in FIG. 7, in which the coated sleeve is used as a shell in a glue stick. 
     By coating the inside of the sleeve with a suitable fluid, cardboard can be used as a material. Previously it was necessary to use plastic or metal to prevent the liquid from leaking out. Due to this design, the use of metal is avoided and the share of plastic is reduced considerably, which makes a marker pen manufactured using paper sleeves according to the present method a more environmentally friendly alternative. At the same time, due to the fact that only the inside of the sleeve is coated, it is entirely possible to print, apply labels to or colour the outside of the sleeve in order to provide the outside of the product with suitable information or give the product an attractive appearance as desired. 
     It is to be understood that the invention is not restricted to the embodiment described above and shown in the drawings, but can be modified within the scope of the following claims.