Raffia Sack

Abstract

 RAFFIA SACK, of the type used for storing preferably granulated and/or powdery substances, said sack (1) featuring a side bellows (3) and a weld (2) forming its tubular shape, said raffia sack being made with raffia which is externally coated with a polyolefin and incorporating a band (6) that seals the rim of the hem resulting from the folding (4) of the bottom of the sack on the body thereof, said band (6) being thermally welded to the body of said sack, thereby forming a bottom featuring an airtight closure.

Description

FIELD OF THE INVENTION

[0001] The object of the present invention is a raffia sack of the type used for storing purposes and/or for transport of granulated or powdery materials, which features a novel manufacturing process that makes it more economical whilst maintaining or improving its qualities.

PRIOR ART

[0002] Sacks have been used since antiquity for the storage of substances, such as grain and powdery materials. The discovery of plastics meant their immediate incorporation as base material for forming sacks.

[0003] There exist different means for forming sacks made of plastic material, both for performing the required forming folds and for creating the means for joining the parts thereof: welding, gluing, stitching, etc.

[0004] Sacks intended to withstand large weights are made of raffia, which is a resistant and coarse fiber used in the ropemaking industry and in woven items. To the extent that raffia provides a resistant and long-lasting fabric that does not suffer deformation it is perfect for making sheets that will become the base for sacks meant to be resistant.

[0005] In general raffia is made of net-shaped braided polypropylene (PP). And the sacks made from a sheet of this material are stitched to form its joinings.

[0006] The main object of the present invention is the manufacture of a resistant and long-lasting raffia sack, through thermal welding, having low manufacturing costs.

[0007] These and other advantages of the present invention will become obvious throughout the description below.

BRIEF DESCRIPTION OF THE INVENTION

[0008] The present invention describes a raffia sack, of the type used to preferably store granulated and/or powdery materials in which the raffia sheet incorporates a polyolefin outer coating.

[0009] This new raffia sheet provided with an outer polyolefin coating is folded to form a tube having a side bellows.

[0010] The bottom is folded on itself and pre-welded with some temperature, there being added a raffia strip that secures both closing and welding through thermal welding.

[0011] Manufacture of the so obtained sack is simple inasmuch as the final product is achieved by means of simple handling mechanical operations that can be automated.

[0012] The sack is efficient and resistant because the thermal welding performed provides great airtightness. The sack is economical because in its manufacture costly stitching operations are dispensed with, thereby it being obtained a final product featuring at least comparable consistency and resistance.

BRIEF EXPLANATION OF THE DRAWINGS

[0013] A sheet of drawings is provided purely by way of illustration, it not being meant to limit the invention but to enhance understanding of the same.

Figure 1 shows a perspective view of a sheet that has been subjected to a tubing process, the sheet has also been provided with side bellows and its ends having been thermally welded.

Figure 2 shows a section of a sack formed in accordance with the present invention.

Figure 3 shows an top view of the sack of the preceding figure.

DETAILED EXPLANATION OF THE INVENTION

[0014] The present invention is a raffia sack of the type used to preferably store granulated and/or powdery substances, said sack (1) featuring a polyolefin outer coating.

[0015] This coating provides the sack with properties that are necessary to properly take part in the process of formation thereof under the present invention. The polyolefin layer applied on the outer surfaces of the raffia sack allows it to display a good behaviour during thermal welding, thereby facilitating the joining of its ends.

[0016] In addition, this outer polyolefin layer permits serigraphy and/or printing of legends and drawings with excellent finish quality.

[0017] As shown in figure 1, in order to make the sack of the invention, in its preferred embodiment, the base material is a raffia sheet provided with a polyolefin outer coating. This sheet is folded and joined together by the ends thereof by means of a weld (2) in a process known as tubing that results in a tube having a side bellows (3).

[0018] The main technical problem to be overcome by the invention is avoiding stitching or gluing to obtain the sack bottom. This is attained, as shown in figures 2 and 3, by means of the folding and welding described below.

[0019] The tube obtained from the aforesaid tubing, figure 1, is by means of a fold (4) turned on itself on its bottom and then thermal pre-welding (5) is performed. A band (6), also made of raffia, is then added at the joining area of the end of the hem obtained from said folding and the body of the sack and, subsequently, the bottom of the sack is thermally welded, as illustrated in said figures 2 and 3.

[0020] The dotted line in said figure 3 shows the side bellows of the sack, the folding (4) on the bottom of the sack, the pre-welding (5) thereof and the welded band (6).

[0021] The aforesaid welds and the band (6) configure the bottom of the sack and create an airtight closure of same.

[0022] In this manner it is obtained with the present invention a sack whose simple manufacture avoids complicated and costly stitching operations, even gluing, by using thermal welding on the raffia material. The joinings forming the sack are very resistant and allow to store loads at least equivalent o even heavier than those to which conventional sacks are subjected.

[0023] It is understood that in the present case details of finish and form may be varied provided the essential nature of the invention is not modified.

Claims

1. RAFFIA SACK, of the type used for storing preferably granulated and/or powdery substances, said sack (1) featuring a side bellows (3) and a weld (2) forming its tubular shape, CHARACTERIZED in that it is made with raffia which is externally coated with a polyolefin, said raffia sack incorporating a band (6) that seals the rim of the hem resulting from the folding (4) of the bottom of the sack on the body thereof, said band (6) being thermally welded to the body of said sack.

2. RAFFIA SACK, according to claim 1, CHARACTERIZED in that both the body of the sack and the body of the hem resulting from the folding (4) against itself of the formative tube are thermally pre-welded (5).

3. RAFFIA SACK, according to the previous claims, CHARACTERIZED in that the bottom of the sack (1) obtained through thermal welding and said band (6) form an airtight closure.

Drawing