TUBE FOR ADHESIVE MATERIAL

Abstract: The tube for adhesive material allows reliable dosing of the adhesive and prevents adhesive from running out prematurely or dripping out after use of the tube. To this purpose, the tube (10) comprises an elastic insert formed as a small plate (21), which plate, e.g. by means of slots (22), is permeable for the adhesive and bulges upon interior pressure within the tube body (11). Since the small plate (21) returns to its initial form when the pressure decreases, adhesive is sucked back from the spout of the tube. Alternatively, fibrous wool having a high wettability with the adhesive is arranged within the tube.

Description: The invention is directed to a tube for adhesive material according to the precharacterizing part of claim 1. A well-known annoyance of hobby workers who use tubes containing viscous adhesives is caused by enormeous difficulties in dozing the adhesive that issues out of the tube. On the one hand, it often happens that more adhesive than desired emerges initially, and on the other hand, the discharge of adhesive cannot be stopped with sufficient accuracy. In order to eliminate these disadvantages, adhesives with a different flowability have been developped. Such adhesives however, which have the flow characteristics of a gel, are often not accepted by consumers. In the case of viscous masses of adhesive, one could use an elastic tube body capable of restoring its former shape, which tube body, after adhesive has been pressed out of it, effects a back suction. However, such a solution would entail the disadvantage that the tube body would not adapt to the decreasing contents as is the case with a tube made of soft metal. If a tube body capable of restoring its former shape would be used, an empty space would be created within the tube body; this empty space would fill with air which could slowly harden the adhesive in the tube and which could expand under thermal influence and after removal of the cap could let the adhesive immediately and uncontrolledly escape due to the overpressure. US-A-3 699 323 discloses a tube for adhesive material wherein the tube body contains an insert supported at the tube shoulder and having a diaphragm 42 for sealing the channel running through the spout. The diaphragm is provided with one ore more slots which automatically open upon fluid pressure acting from the interior of the tube body, to thereby allowing the contents of the tube to escape through the spout. The insert with the slotted diaphragm acts as an one-way valve for passing the contents of the tube only in outward direction and for avoiding that residual or undispensed product in the tube neck will be drawn or sucked rewardly into the tube container. The insert supported at the tube shoulder and the small plate acting as a non-return valve constitute one single integral component wherein the slots have to be cut by use of a cutting die. It is the object of the invention to provide a tube for adhesive material which effectively prevents uncontrolled issuing of adhesive material and outflow of adhesive material after use of the tube, wherein the commonly known tubes consisting of a tube body and the spout can be used without being altered and are only provided with an additional device. According to the invention, this object is solved by the features indicated in the characterizing part of claim 1. Using an elastic small plate, however, does not completely eliminate yet a further problem resulting from changes in temperature acting upon the tube. When the tube is heated, it is possible that the part of the tube that has already been flattened starts bulging out again. If the plate had only a very small inherent stability, then the pressure within the tube would open the plate, thus rendering control of the emerging adhesive impossible. Advantageously, the plate should have a higher stability against pressure than the tube body. Thus, it is effected that upon changes of temperature it is exclusively the tube body that is deformed while the plate is maintained in the closed state without bulging. On the other hand, the stability of the plate against pressure must not be selected so high that the plate offers too much resistance when adhesive is pressed out of the tube. Preferably, the slots of the small plate open only after a certain initial deformation of the plate so that for opening of the slots, a threshold pressure has to be overcome first. This effect can be obtained by providing the plate with a cross bar delimited by two slots. When the plate is being curved, the edges of the slots are not pressed apart immediately, moreover, the two slots open only after a specific pressure of the adhesive has been overcome. The difference in deformation between the cross bar and the sides of the plate becomes even larger and the danger of kinking is further diminished when the cross bar is concavely formed. After each use of standard tubes containg adhesives, a tiny air bubble penetrates into the tube when the pressure on the tube body decreases. These air bubbles accumulate in the tube body because only a small part of them is blown out again during normal use. The more often the tube has been used, the larger becomes the volume of air accumulated therein. A tube which contains a large volume of air presses adhesive to the outside under even the slightest thermal influence, and the escaping of adhesive could be further favoured by the gas pressure originating from the solvent. The small plate according to the invention does hinder the intrusion of air but is not adapted to entirely prevent this intrusion because in the closed state of the tube, pressure can accumulate in the antechamber in front of the plate and push a small amount of gas into the tube. According to the invention, a spout insert is arranged in the spout in order to prevent the rising of air bubbles, said insert of the spout extending in lengthwise direction of the spout and dividing or narrowing the section of the passage of the spout. In this manner, comparatively narrow tubes are provided which hinder air from entering the tube body. The insert can consist of a spider structure or a conical spout insert. Preferably, the spout insert and the small plate are combined to form a functional unity, the edge of the plate abutting the shoulder of the tube and being lifted from said shoulder upon pressure on the central area of the plate. Of course, the bending moment of the pressurized surface of the central area of the plate must be larger than the bending moment acting on the outer edge surface. When filling in the adhesive, no particular precautions are needed for filling the volume before the plate since this volume is very small and thus negligable. A further advantage consists in the fact that the plate need not be fastened directly to the tube and, moreover, cannot jam and moves freely. Therefore production tolerances with regard to the tube and the plate as well as thermal extension of these parts cause no problems. The same tube insert and the same plate can be used equally for tubes of different sizes. When the plate and the nozzle insert are manufactured of plastics material, this plastics material must be resistant to adhesive. In this respect, for example polyethylen is well suited. Embodiments of the invention will be explained in greater detail hereinafter with regard to the drawings. In the drawings - Fig. 1 shows a combination of the spout insert and the small plate, Fig. 2 shows the construction according to Fig. 1 in the mounted state, Fig. 3 shows a further embodiment of the spout insert, and Fig. 4 shows the small plate belonging to the spout insert according to Fig. 3. Figs. 1 and 2 show an embodiment of the invention. The tube consists of an initially cylindrical tube body 11 made of soft metal. At the one end of the tube body 11, there is provided a comparatively rigid truncated tube shoulder 12 being joined to the spout 13. Following the tube shoulder 12, the spout 13 comprises a threaded portion, and, following the threaded portion, a conical mouthpiece. A threaded cap covering mouthpiece can be screwed onto said threaded portion. The spout insert 30 consists of a cross- or spider-shaped structure. By this structure, the channel extending through the spout 13 is divided into a plurality of channel portions. The spout insert 30 is provided with arms 32 projecting radially to the outside, abutting the inner wall of tube shoulder 12 and carrying pins 33 protruding into tube body 11. Said pins 33 project respectively into openings 34 of plate 31 and support the plate against the pressure of the adhesive. If a pressure exists within the tube body, the plate 31 is curved toward spout 13 with the edge area of the plate being lifted from tube shoulder 12 so that an annular passage for the adhesive is created between the edge of plate 31 and the tube shoulder 12. In the construction according to Figs. 3 and 4, the spout insert 30a is made of a single one-pieced sheet comprising a narrow bar 35 projecting into mouthpiece 15 and being joined by to a wider bar 36 supported within threaded portion 14. The bars 35 and 36 divide the channel running through spout 13 into two channel portions. The wider part 36 is joined by a headpiece 37 having inclined flanks 38 abutting against the inner side of tube shoulder 12. The headpiece 37 has an opening 39 formed therein which is limited at the front by an arch-shaped edge 40 extending across the largest width of opening 39. In the opening 39, there is inserted the small plate 31a shown in Fig. 17, which plate 31a is circular and has its edge provided with two diametral slots 41. The plate 31a is clampingly arranged in opening 39, thus crossing this opening and abutting with its edge against tube shoulder 12. In case of pressure within the tube body 11, plate 31a bulges towards the edge 40. Upon bulging of the plate 31a, the edge thereof is lifted from the tube shoulder 12, thus providing an annular passage which allows adhesive to enter spout 13.

Claims: Tube for adhesive material, preferrably made from soft metal, comprising a flexible tube body (11) and a rigid spout (13), wherein the spout (13) contains an insert (30,30a) for supporting a plate (31,31a) for hindering the intrusion of air through the spout, said plate (31,31a) providing a passage for the contents of the tube upon deformation by fluid pressure within the tube body (11), characterized in that the insert (30,30a) supports the plate (31,31a) at locations spaced from the plate edge and the elastic plate (31;31a) has its edge abutting the tube shoulder (12), so that the plate edge is lifted from the tube shoulder when pressure is exerted on the center area of the plate. Tube for adhesive material according to claim 1, characterized in that the insert (30) comprises a cross- or spider-shaped structure (31) dividing the channel through the spout (13) into a plurality of channel portions. Tube for adhesive material according to claim 1, characterized in that the insert (30a) comprises single one-piece sheet extending into the mouthpiece (15) of the spout (13) and deviding the channel through the spout (13) into two channel portions. Tube for adhesive material according to any one of claims 1-3, characterized in that the plate (31) has a slightly larger stability against pressure than the tube body (11).

Inventors: KROEBER, LUTZ
Applicants: KROEBER, LUTZ
Application year: 1988
Main classification: B65D35
IPC codes: B65D35, B65D47, B05C17