IT202000013471A1 - Bag free of plastic elements with high protection against humidity and water - Google Patents

Description

Patent description for industrial invention having the title:

?Bag free of plastic elements with high protection against humidity? and from the water?

DESCRIPTION

Field of invention

The present invention relates to a sack for transporting materials. In particular, the present invention relates to a sack for transporting cement, or other material useful in various food, chemical, building sectors, free of plastic elements (?plastic free?) and with high resistance to humidity? and to the water.

State of art.

Currently, for the transport of cement and other similar material in the building sector, as well as? for the transport of other kinds, for example in the food, chemical, and for the transport of minerals, bags made of paper and plastic are used.

Typically, the bags known in the art consist of two overlapping sheets of paper of the type, for example, of 80 g/m<2>, between which a sheet of plastic, typically high-density polyethylene, is interposed. (HDPE), or with a density? in the range between 0.945 and 0.965 g/cm<3 > and a thickness for example of about 7 microns.

These bags show a moderate resistance to humidity, even if stored for a long time in a humid environment.

However, these bags have the drawback of containing plastic elements; considering the very high number of bags of this type used all over the world for the transport of various materials, the fact of containing plastic elements constitutes a serious problem from an environmental point of view.

Therefore, the Applicant yes? posed the technical problem of how to effectively and economically make plastic-free bags for the transport of cement, adhesive and other similar material, which are still able to protect against humidity? the material contained therein.

Summary of the invention

In a first aspect, the present invention refers to a sack such as the one indicated in claim 1.

The Applicant of the present application has in fact surprisingly found that the technical problem encountered above can solved effectively and reliably by means of a bag suitable for containing cement, or other similar material, consisting of at least two sheets of paper superimposed on each other, characterized in that the external sides of said sheets are covered with at least one layer of hydrophobic paint.

In this way, since the varnish is distributed on the outer side/face of the paper sheets, and therefore not on the face facing the inside of the bag, contact between the varnish and the product contained inside the bag is avoided.

This varnish transfers water-repellent characteristics to the paper; in this way both the transmission of humidity/water vapor (WVTR) and the absorption of water (COBB) are considerably reduced.

In fact, thanks to at least one layer of varnish applied externally to the sheets of paper that make up the bag, the water is not retained by the paper, but slips away due to the high surface tension present on the treated paper.

Is it obtained like this? a highly hydrophobic surface in the sense pi? broad of the term, to indicate the property? not to absorb and not retain water.

Comes like this? increased the barrier effect compared to that obtainable from standard plastic bags known in the art, guaranteeing the product contained inside the bag a high protection from humidity, even in the absence of intermediate polythene plastic sheets in the construction of the bag bag, and consequently improving the shelf life of the product contained inside the bag.

In particular, the bag of the present invention is free from plastic elements (?plastic free?), while maintaining high shelf conservation performance against humidity? and water.

The term ?bag?, in the present description and in the attached claims, means a bag, sack or any container or package of the type wrapped in a reel that can be printed with inks and paints, capable of safely transporting and keeping the material intact content, this material being of solid, semi-solid, or granular form, of the various product classes such as, for example, earth, sand, cement, stucco, or other material useful in the building sector, as well as such as feed, seeds, food for animals and food for people, or other material useful in the food, chemical or for the transport of minerals and the like, and this container being such as to be able to assume the shape determined by the material in its entirety? contained within it.

According to a preferred embodiment, said sack ? consisting of at least three, such as three, four, five or greater number of sheets of paper superimposed on each other.

According to a preferred embodiment, said hydrophobic varnish ? water-based wax type, such as a polymer wax.

According to a preferred embodiment, said hydrophobic varnish ? a mixture that contains at least one element of the isothiazol-3-one type, such as 1,2-benzisothiazol-3(2H)-one, 5-chloro-2-methyl-2H-isothiazol-3-one (CMIT), and /o 2-methyl-2H-isothiazol-3-one, and mixtures thereof.

According to a preferred embodiment, said hydrophobic varnish has a pH between 8 and 9.

According to a preferred embodiment, said hydrophobic paint has a density of relative of about 1 g/cm<3 >at 20?C.

According to a preferred embodiment, said hydrophobic paint has a viscosity < 2000 mPas, preferably < 1500 mPas.

According to a preferred embodiment, said varnish is distributed on each of said sheets of paper with a basis weight in the range from about 4 g/m<2> to about 9 gr/m<2>.

According to a preferred embodiment, said varnish is distributed on each of said sheets by means of the spreading process, i.e. an industrial process which comprises the uniform application of said varnish on said sheets, drying in an oven, eventual calendering or embossing, and subsequent cooling.

According to a preferred embodiment, said sack ? consisting of a main lateral outer surface and at least one lower bottom plate fixed to said main outer surface, wherein each of said main lateral outer surface and of said lower bottom plate ? consisting of at least two of said sheets of paper superimposed on each other and coated with at least one layer of hydrophobic varnish.

In this way the bag appears as if it were made up of a single body.

Preferably, the consistency of the external lateral surface of the bag is such as to allow the bag itself to assume the shape defined by the mass of the material contained therein.

Preferably, said lower base has a flat, partially rigid surface, such as to be able to act as a ground support base for the bag. In this way, since the lower base has a substantially flat dimension, it is easier to place the sack on the ground on flat surfaces in a vertical position when the sack is on the ground. full, or partially full.

In one embodiment, preferably, said sack ? also consisting of an upper base, substantially similar to the lower base; in this way ? It is possible to place the bag on the ground both using the lower base as a support base on the ground and, conversely, using the upper base as the support base. This ? particularly useful when the bag to be placed on the ground does not have a part that must necessarily be facing upwards and one facing upwards.

According to a preferred embodiment, said upper bottom ? consisting of at least two of said sheets of paper superimposed on each other and coated with at least one layer of hydrophobic varnish.

In an alternative embodiment, the bag of the present invention is of the type defined as ?open mouth?, where not ? present said upper bottom; the sack in this alternative embodiment in fact has the upper part of the side surface open so that it can be easily filled. Once the sack ? been filled, this opening is closed with special sealing machines.

According to a preferred embodiment, the inner sides of said at least two sheets are glued together at the ends of the sheets. upper and of? extremity? bottom of said sheets so as to create a sort of tube inside the bag.

According to a preferred embodiment, the inner sides of said at least two sheets are glued to each other at points arranged in correspondence with said ends. top and bottom.

According to a preferred embodiment, the inner sides of said at least two sheets are glued together by means of starch glue or vinyl glue.

According to a preferred embodiment, said paper can be chosen from the group consisting of Kraft type paper, high porosity Kraft type, glossy paper, semi-extensible paper, MG paper, or rather a type of wrapping paper provided with a glossy and shiny face and the other rough, glossy or matte one-sided coated, duplex smooth paper, cardstock and the like.

Preferably, each of said sheets of paper of said main lateral outer surface of said bag has a weight per square meter of the order of from about 70 to about 120 g/m<2>, preferably about 90 g/m<2>.

Preferably, said bottoms have a weight per square meter of from about 60 to about 100 g/m<2>, preferably about 90 g/m<2>.

According to a preferred embodiment, said sack further comprises closing systems along a longitudinal line of the outer lateral surface of the sack which extends substantially from said lower bottom to said upper bottom, wherein said closing systems comprise escape routes for ensure that the air escapes from the inside of the bag.

In this way a better total deaeration of the bag is obtained.

According to a preferred embodiment, said bag comprises at least one sheet of polythene interposed between two of said layers of paper coated with said hydrophobic varnish. This further reduces the transmission of humidity/water vapor (WVTR) inside the bag.

Further characteristics and advantages of the present invention will become clearer from an examination of the following detailed description of preferred, but not exclusive, embodiments, illustrated only for indicative and non-limiting purposes with the support of the attached drawings. In particular, in such drawings:

- Figure 1 ? a view of an empty bag according to an embodiment of the present invention, in which the lower bottom and the upper bottom folded over the side surface are visible;

- Figure 2 schematically shows how the two sheets of paper which make up the bag are glued together;

- Figure 3 shows another embodiment of the sack of the present invention, in which the escape routes are visible along the longitudinal line;

- Figure 4 shows a side view of Figure 3, in which the escape routes along the longitudinal line are further visible.

Detailed description

The following detailed description refers to particular embodiments of the device of the present invention, without limiting its content.

The sack of the present invention ? suitable for containing cement, or other similar material useful in the building industry, or in the food, mineral, chemical sector, such as for example sand, gravel, or other material useful for example in the animal feed and seed sector or the like.

Example 1 (invention). Bag 1 shown in Figure 1 ? consisting of a main lateral external surface 2, a lower bottom 3 and an upper bottom 4 fixed to the main external surface 2, so as to make the bag 1 appear as if it consisted of a single body.

The lower bottom 3 and the upper bottom 4 comprise a flat, partially rigid surface, such that it can be folded over the side surface 2 when the bag is in the process of being folded. empty, so as to be able to store the bag occupying the minimum space necessary, and such as to be able to act as a base for the bag, when this is at least partially filled and placed in an upright position.

Bag 1? consisting of two sheets of paper; especially the sack ? consisting of an outer sheet of semi-extensible paper, having a weight of about 90 g/m<2>, superimposed on an inner sheet of paper of the semi-extensible type, also having a weight of about 90 g/m <2>. The outer sheet has a width that extends at least 20mm beyond the width of the inner sheet, to facilitate lengthwise gluing.

The internal and external sheets of paper of the lower base 3 and of the upper base 4 each have a weight of slightly about 70 g/m<2>.

The internal and external paper sheets of both the side surface and the bottoms are coated by spreading with a layer of hydrophobic varnish of the polymeric wax type, with a coverage of approximately 5 g/m<2>. The hydrophobic paint used? a mixture containing 1,2-benzisothiazol-3(2H)-one, 5-chloro-2-methyl-2H-isothiazol-3-one (CMIT), and 2-methyl-2H-isothiazol-3-one, with a including pH of about 8.5, a density? relative of about 1 g/cm<3 >at 20?C and a viscosity? < 1,500 mPas.

The inner sides of the two inner and outer sheets of paper are glued together at their ends. upper and lower through transversal gluing, so as to create a sort of tube inside the bag (see figure 2). The gluing between the sheets takes place by points 7 arranged in correspondence with their ends? top and bottom, using starch glue.

Bag 1 not ? provided with holes like some conventional bags known in the art.

As shown in Figures 3 and 4, the bag ? also equipped with escape routes 6, arranged along the longitudinal line 5, consisting of aeration zones created by the absence of glue in these points, to favor the escape of the air from inside the bag. The bag 1 is filled with cement, or other similar material as indicated above, and subsequently suitably closed according to the traditional filling and closing methods for these types of bags. For example, concrete can be inserted inside the bag through an opening obtained in this lower chamber 3, an opening which is subsequently closed automatically at the end of the bag filling phase, by means of a particular valve of which ? supplied such lower burner 2. The bag cos? filled and subsequently closed, it is subjected to continuous exposure to water for at least 7 days.

Example 2 (comparison).

As comparative example 2, a sack is taken which differs from the sack of the invention shown in Example 1 in that the two sheets of paper composing it have not been coated with a layer of hydrophobic varnish.

Test

Example 1 of the invention and the comparative example were subjected to various tests described below to verify their properties.

Test 1: to determine the permeability? in the air of the sheets of paper, ? was used the Gurley method, as described in ISO 5636-5, with permeability? to air between 0.1 ?m/(Pa?s) and 100 ?m/(Pa?s), expressing the test results in seconds.

Test 2: to determine the water absorption of paper, ? The Cobb method described in the European standard EN ISO 535 was used, using 3 different contact times (60 seconds, 120 seconds, 300 seconds) and expressing the test results in g/m<2>.

Test 3: to determine the properties? of tensile strength of paper sheets after immersion in water (wet strength) ? The test method described in the ISO 3781 standard was used, expressing the test results as a percentage.

Test 4: To determine reliable values of water vapor transmission (WVT) through paper sheets, ? The test method described in ASTM E96//E96M-15 procedure E was used, both in the standard environmental condition of 23?C and 50% humidity? relative that in limit conditions, tropical of 38?C and 90% of humidity? relative, expressing the test results in g/m<2 > for 24 hours.

Table 1 below shows the results of the various tests.

Table 1

From Table 1 you can? note that the sample 1 of the invention, in which the two layers of paper have been coated with hydrophobic paint, in the absence of intermediate plastic layers, improves the permeability? in the air by 360 times (test 1 of Gurley) compared to the comparison sample 2. Furthermore, the sample 1 of the invention has a capacity? very low in absorbing water (test 2 at 60 seconds), about 6 times less than a standard paper, so water tends to slip away very easily. Even by performing the same test 2 with other duration times (120 and 300 seconds) you can? note that the sample 1 has a capacity? to absorb water much more? low compared to a standard card (about 7 and 8 times less, respectively).

With reference to test 3, sample 1 of the invention gives the paper 10% more? of resistance to damp, in case it undergoes exposure to the elements. In the standard bag, however, there are no variations in yield.

With reference to test 4, both in standard environmental conditions of 23?C and 50% humidity? relative that in limit conditions, tropical of 38?C and 90% of humidity? relative, the sample 1 of? the invention gives a permeability? steamed 82% and 80% better than standard, respectively.

Therefore, the bag of the present invention, despite having no intermediate layers of plastic, thanks to the external coating provided by a layer of paint, provides excellent results of humidity absorption, which allows a long shelf life of the product contained in the bag. inside of the bag.

Of course, many modifications and variations of the preferred embodiments described above will be apparent to those skilled in the art, still remaining within the scope of the invention.

For example, ? Is it possible to make other embodiments which differ from that of Example 1 seen above, due to the fact a) of having three or more? sheets of paper (even up to five sheets of paper), instead? two, all covered with a layer of paint on the outside, or b) due to the fact that a sheet of polyethylene is interposed between the two sheets of paper, or c) due to the fact that, in addition to the two or more ? sheets of paper coated with varnish, an additional sheet of paper to which the external layer of varnish is not applied, with or without the interposition of a polyethylene sheet. Therefore, the present invention is not limited to the preferred embodiments described, illustrated only by way of non-limiting example, but ? defined by the following claims.

Claims (10)

Claims. 1. Bag consisting of at least two sheets of paper superimposed on each other, characterized in that the outer sides of said sheets are coated with at least one layer of hydrophobic paint. 2. Bag according to claim 1, consisting of at least three, such as for example three, four, five or a greater number of sheets of paper superimposed on each other. 3. Bag according to claim 1 or 2, wherein said hydrophobic paint is of the water-based wax type, such as a polymer wax, which includes at least one element of the isothiazol-3-one type, such as 1,2-benzisothiazol-3(2H)-one, 5-chloro-2 -methyl-2H-isothiazol-3-one (CMIT) and/or 2-methyl-2H-isothiazol-3-one, and mixtures thereof. The bag according to any one of the preceding claims, wherein said varnish is distributed on each of said sheets of paper with a basis weight in the range from about 4 gr/m<2> to about 9 gr/m<2>. 5. Bag according to any one of the preceding claims, consisting of a main lateral external surface and at least one lower bottom fixed to said main external surface, wherein each of said main lateral external surface and of said lower bottom consisting of at least two of said sheets of paper superimposed on each other and coated with at least one layer of hydrophobic varnish. 6. Bag according to any one of the preceding claims, wherein said bag is furthermore also constituted by an upper bottom fixed to said main external surface, in which also said upper bottom ? consisting of at least two of said sheets of paper superimposed on each other and coated with at least one layer of hydrophobic varnish. 7. Bag according to any one of the preceding claims, wherein the inner sides of said at least two sheets are glued to each other at the end of the bag. upper and of? extremity? bottom of said sheets so as to create a sort of tube inside the bag. 8. A bag according to claim 7 wherein the inner sides of said at least two sheets are glued together at points located at said ends. top and bottom. 9. Bag according to claim 7 or 8 wherein the inner sides of said at least two sheets are glued to each other by means of starch glue or vinyl glue. 10. Bag according to any one of the preceding claims, wherein said bag further comprises closing systems along a longitudinal line of the outer lateral surface of the bag extending substantially from said lower bottom to said upper bottom, wherein said closing systems comprise escape routes to ensure that the air escapes from the inside of the bag.