Method for gumming portions of a material in sheet form

Abstract: A method for gumming portions of a material in sheet form, according to which hot-setting glue and cold-setting glue are distributed on portions (2, 4; 10, 12) of the material in sheet form, so as to form respective hot-setting glue distribution regions (8) and cold-setting glue distribution regions (9); the hot-setting glue and the cold-setting glue are distributed so that each cold-setting glue region (9) is shaped so as to enclose at least one hot-setting glue region.

Description: The present invention relates to a method for gumming portions of a material in sheet form. In particular, the present invention relates to a method for gumming portions of a material in sheet form which can be mutually coupled by overlapping. In general, gumming portions of a material in sheet form to be mutually coupled by overlapping is usually performed by applying to at least one of the portions an adhesive substance which is distributed at room temperature and is referenced hereinafter as "cold-setting glue". The use of said cold-setting glue on the one hand ensures durable gumming but on the other hand does not allow quick setting of the freshly coupled parts, which must be kept stable for a relatively long period required for the drying of said cold glue. In order to overcome this drawback, it is known to apply to at least one of the portions hot-melt glue, hereinafter referenced as "hot-setting glue", i.e., a glue which can be applied and/or activated by heating and is adapted to ensure immediate setting, and simultaneously apply cold-setting glue to said portion, so as to provide cold-setting glue distribution regions and hot-setting glue distribution regions. The use of said hot-setting glue, however, entails the drawback that it releases into the air, during the activation or setting step, highly unpleasant fumes and/or vapors.. The aim of the present invention is to provide a method for gumming, by using both of said kinds of glue, portions of a material in sheet form which does not entail the above drawback. According to the present invention, a method for gumming portions of a material in sheet form is provided comprising the steps of distributing, on said portions, hot-setting glue and cold-setting glue to form, on said portions, respective hot-setting glue distribution regions and cold-setting glue distribution regions; said method being characterized in that said hot-setting glue and said cold-setting glue are distributed so that each cold-setting glue region is shaped so as to enclose at least one hot-setting glue region. The present invention is herewith described with the aid of the accompanying drawings, which illustrate some non-limitative embodiments thereof and wherein: Figure 1 is a schematic perspective view of a preferred embodiment of a gumming unit which provides the method according to the present invention; and Figures 2, 3 and 4 are views of three further embodiments of the unit of Figure 1. With reference to Figure 1, the reference numeral 1 designates a gumming unit adapted to distribute hot-setting glue and cold-setting glue on a central portion or band 2 of a sheet 3, which is fed by a conveyor, not shown, in an advancement direction D1. The band 2 of the sheet 3 is adapted to be superimposed, by means of conventional coupling means which are not shown, on a central portion or band 4 of a corresponding sheet 5, which is fed by a conveyor, not shown, in said direction D1. The unit 1 comprises a gumming nozzle 6 which is connected, in a conventional manner not shown, to a reservoir for feeding hot-setting glue in order to distribute hot-setting glue on the band 2, and a gumming nozzle 7, which is connected, in a conventional manner not shown, to a reservoir for feeding cold-setting glue arranged downstream of the nozzle 6 in the advancement direction of the sheet 3 in the direction D1 in order to distribute cold-setting glue on said band 2 so as to form, on said band 2, a hot-setting glue distribution region 8 and a cold-setting glue distribution region 9. As shown in Figure 1, on the band 2 of the sheet 3 the region 9 is formed by a uniform annular distribution or application of cold-setting glue which encloses a spot 8 of hot-setting glue. According to further embodiments, not shown, the spot 8 of hot-setting glue and the region 9 of cold-setting glue are provided on both of the bands 2 and 4 to be superimposed or only on the band 4 of the sheet 5. As a consequence, the unpleasant fumes produced by the hot-setting glue cannot diffuse into the air, since the annular application of cold-setting glue that constitutes the region 9, as a consequence of the coupling of the sheet 3 to the sheet 5, shields the spot 8 of hot-setting glue, preventing the vapors of said hot-setting glue from reaching the environment during its activation and setting. In the further embodiment shown in Figure 2, the distribution of the hot-setting glue and of the cold-setting glue on the part of the gumming nozzles 6 and 7, with a region 9 which encloses a spot 8 of hot-setting glue, is formed on a lateral portion or flap 10 of a sheet 11, which is fed by a conveyor, not shown, in an advancement direction D2 and can be used, for example, to form a tubular wrapping by superimposing the flap 10 on a respective flap 12 of said sheet 11. According to further embodiments which are not shown, the hot-setting glue spot 8 and the cold-setting glue region 9 are formed on both flaps 10 and 12 of the sheet 11 to be superimposed or only on the flap 12 of said sheet 11. In the further embodiments shown respectively in Figures 3 and 4, the hot-setting glue is distributed by the nozzle 6 only on the band 4 of the sheet 5, or only on the flap 10 of the sheet 11, while the cold-setting glue is distributed by the nozzle 7 only onto the band 2 of the sheet 3 or only on the flap 12 of the sheet 11. In this manner, by superimposing the band 2 on the band 4, or the flap 10 on the flap 12, a cold-setting glue region 9 encloses a spot 8 of hot-setting glue. The disclosures in Italian Patent Application No. BO98A000137 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: A method for gumming portions of a material in sheet form comprising the steps of distributing, on said portions (2, 4; 10, 12), hot-setting glue and cold-setting glue to form, on said portions, respective hot-setting glue distribution regions (8) and cold-setting glue distribution regions (9); said method being characterized in that said hot-setting glue and said cold-setting glue are distributed so that each cold-setting glue region (9) is shaped so as to enclose at least one hot-setting glue region (8). The method according to claim 1, characterized in that said region (9) of cold-setting glue is formed by distributing said cold-setting glue around at least one hot-setting glue region (8). The method according to claim 1, characterized in that said portions (2, 4; 10, 12) are formed by respective bands (2, 4) of a first sheet (3) and of a second sheet (5) of said material which can be coupled by overlapping; said regions (8) of hot-setting glue being formed on the band (4) of said second sheet (5) and said regions (9) of cold-setting glue being formed on the band (2) of said first sheet (3). The method according to claim 1, characterized in that said portions (2, 4; 10, 12) are formed by respective bands (2, 4) of a first sheet (3) and of a second sheet (5) of said material which can be coupled by overlapping; said regions (8) of hot-setting glue and said regions (9) of cold-setting glue being formed on at least one of said bands (2, 4). The method according to claim 1, characterized in that said portions (2, 4; 10, 12) are formed by a first flap (10) and a second flap (12) of a sheet (11) of said material which can be coupled by overlapping; said regions (8) of hot-setting glue being formed on said first flap (10) and said regions (9) of cold-setting glue being formed on said second flap (12). The method according to claim 1, characterized in that said portions (2, 4; 10, 12) are formed by a first flap (10) and a second flap (12) of a sheet (11) of said material which can be coupled by overlapping; said regions (8) of hot-setting glue and said regions (9) of cold-setting glue being formed on at least one of said flaps (10, 12). The method according to claim 1, characterized in that each one of said regions (8) of hot-setting glue comprises a spot (8) of hot-setting glue; said region (9) of cold-setting glue comprising a uniform annular distribution (9) which encloses at least one of said hot-setting glue spots (8).

Inventors: SPATAFORA MARIO, SPATAFORA, MARIO
Applicants: GD SPA, G.D S.P.A.
Application year: 1999
Main classification: C09J7
IPC codes: C09J7