WO1991014632A2

WO1991014632A2 - Self-evacuating bag and process for filling it

Info

Publication number: WO1991014632A2
Application number: PCT/DE1991/000233
Authority: WO
Inventors: Felix Rettenmaier
Original assignee: Celcommerz High-Chem.-Produkte Gmbh & Co. Kg
Priority date: 1990-03-23
Filing date: 1991-03-19
Publication date: 1991-10-03
Also published as: DE4009369A1; WO1991014632A3; KR910016569A; EP0473753A1; JPH05500493A; AU7495091A

Abstract

The self-evacuating bag proposed is designed to be filled with fine-particulate materials and consists entirely or partly of air- and gas-permeable non-woven material having a permeability to air and other gases which is high enough for air or other gases which accumulate in the bag during filling to escape through the non-woven.

Description

Self-venting sack and method for filling it.

The invention relates to a self-ventilating sack for filling with finely divided material such as powders, grains, flakes, fibers, in particular with fillings of low weight.

The packaging of granular, powdered or fibrous mate ^¬ rials is mechanized in recent years increasingly and been automated, in particular with the aim of labor and time saving and Abpackungsauto- maten use. This mechanization and automation places a whole series of requirements on the bag-shaped or bag-shaped packaging means used, some of which are incompatible with one another.

For example, efforts are being made to further shorten the cycle time of corresponding devices in packaging machines and thus to increase the utilization and effectiveness of the machines, which often require considerable investments. This is an obstacle to the fact that air or other gaseous substances are entrained during the packing process, the bags inflate and trapped air can only escape slowly. Attempts have been made to remedy the situation in a wide variety of ways, for example by constructive measures on packaging machines, for example through air outlet openings the filler neck of valve bag filling devices, or by the introduction of small holes in the packaging material ^¬, the so-called needles of the material, so that there is a selbstentlüf forming bag.

A satisfactory solution of the problem has thus not be achieved because, for example, in valve bag filling ^¬ the effort machines is great for removing the air necessary for the promotion and control of the contents, corresponding devices are vulnerable and Abluf problems entsytehen because during the removal of the air, finely divided ^'material entrained and must be laboriously collected. In .the action of needling of the material that makes up the selbstent¬ ventilating bag are, insofar limits for Öffnun¬ gen in which air set because in the needling beispeilsweise of foil material or kraft paper which comes through ^¬ finely divided filler such as flour that dust must be prevented. Very small holes, on the other hand, clog up quickly so that the intended effect of quickly removing entrained air is not achieved.

These problems are particularly great for powdered or fibrous fill goods with a high specific surface area because the powder or fibers bind a great deal of air to them. Flour, cellulose powder,. Silica gels, textile fibers, down and similar materials are typical examples. Has the adhesion of air or any other gases employed for packing the additional disadvantage that the bags initially remain ballonartig.aufgebläht and sύhwierig transportable and stackable, are the other filled inadequately, much Pack ^'is space wasted and the bags because of the blank ¬ unsightly and difficult to transport and stack. There is therefore an urgent need. rfnis for a self ^¬ vented bag that does not have these disadvantages, allows a time- and space-saving filling of the bag and it allows to use the given by the bag shape room full .auszu¬ save transport and safe and stacked to save space. In addition, the sack must of course have sufficient strength to withstand the filling pressure during automatic filling and to be able to cope with the load caused by the filling material. Since this problem is particularly severe in the case of valve bags, since short cycle times are sought when they are filled, the invention is explained in more detail below using the example of a valve bag, but without being limited to this specific example. The self-venting sack is also important when filling sacks by other means, for example from open sacks via screw conveyors or even when shoveling in the filling material, and is advantageous ^" .

Since the problems outlined above exist in particular in the case of fine-particle fill goods with only a low density, as mentioned at the beginning, the invention will be explained in the further course with these examples. However, the advantages are also available with other filling materials such as cement powder.

Surprisingly, the property profile shown above can be fulfilled and the task can be solved with a self-venting sack, which consists entirely or partially of air- and gas-permeable nonwoven fabric, the air and gas permeability of which is so great that it becomes congested during filling Air or gases can escape through the nonwoven.

Which definite values of air permeability and other properties the nonwoven fabric required for the sack according to the invention has to meet depends on a large number of factors which are mutually dependent and interdependent. On the one hand, this affects the filling material to be filled in terms of a number of influencing factors as part ^¬ specific weight-size in, .Temperature, package size and package weight and possibly chemically and physically existing aggressiveness. Of course, the nonwoven fabric has a bag for bagged cement of very high specifi ^¬ rule weight and a ver by the foregoing grinding ^¬ tively high temperature higher strength values greater thickness and higher basis weight than a bag for filling with down or silica gel.

On the other are the properties of the Vliesstof¬ used fes in mutual dependence such as air permeability, weight per unit area ^", thickness of the nonwoven fabric, size whose pores ^* and the number of pores, the nature of the nonwoven used, and the binding of the fibers or the type fleece bonding, so that only wide ranges can be specified for these values, within which a selection must be made for the special purpose.

In terms of air permeability, there is a preferred

2 rich at 100 to 3000 1 / m / s measured according to DIN 53887 and the range from 400 to 2000 1 / m 2 / s has proven to be particularly advantageous for most filling materials and nonwovens. At a

2 Air permeability below 100 1 / m / s also builds up in this _. extremely suitable material, too high a pressure and the sack may be damaged. If the air permeability is higher than 3000 1 / m / s, the nonwoven is either too thin or has too large pores or both and then no longer adequately protects the filling material from external influences and allows finely divided ingredients to escape, ie lead for dusting and no longer has the required strength.

With regard to the appropriate basis weight, the limit

2 values at 30 to 200 g / m for the nonwoven fabric, preferably at 40

2 to 150 g / m. Here too, the contents, package size, art - zz>

and manner of packaging, among other things, of influence. It will be evident ^¬ Lich that when filling by hand Einschaufeln the Anfor ^¬ changes in strength are with respect to substantially less than during the filling of a valve bag with a relatively high filling pressure and ^¬ excessively short cycle time.

The thickness of the nonwoven fabric is also in an interrelation and dependency relationship with the other sizes. It is expediently in the range from 0.1 to 1.5 mm, preferably from 0.2 to 1 mm. A relatively thin fleece must have high strength values in order to withstand the stresses during filling and when handling and storing the filled sack. •; . .

Another influencing factor is the size and frequency of the pores in the nonwoven fabric. Ultimately, these pores determine the degree of air permeability and thus the suitability for rapid self-ventilation. Above all, their size has a decisive influence on the tightness of the bag and the prevention of dusting when filling and when handling the filled bag later. Above all, the maximum pore size is a limiting factor here, which should preferably not be above 150 μm for most of the filling goods mentioned at the beginning. The pore size also shows the dependency on other data of the nonwoven, and it is obvious that a thin nonwoven with relatively large pores tends to dust more easily than a thicker nonwoven with the same size pores or a larger number of medium and smaller pores, because at a thicker nonwoven fabric, the probability that a small particle of the filling material is filtered out and thus prevented from escaping is multiplied.

It follows from all of this that the properties of the nonwoven as an exclusive or area-dominant material is of crucial importance. The wide range of variations in terms of properties that exist in the nonwovens field, on the other hand, this group of substances makes them just as suitable for solving the posed ones _. Task and to adapt to the variety ^¬ number of materials to be filled, packaging and filling ^¬ devices.

The term nonwoven is to be interpreted broadly and encompasses all materials that contain exclusively or to a considerable extent textile fibers with a length between 3 mm and 50 mm, are stored in a random position by a dry or wet process and are consolidated in various ways, for example. mechanically by needles or chemically by binders and / or thermally by heat treatment. For this new and interesting group of fabrics, which occupies an intermediate position between paper and woven and knitted fabrics, the English term non woven fabric has become common. Also to be included in this group of substances are spun-bonded materials, in which synthetic materials such as polyester during the manufacturing process from the melt, i.e. when the threads or fibers emerge from a nozzle, are deposited in different directions and solidified to form a sheet material while still plastic. The delimitation of the nonwovens is that paper consists of short fibers based on cellulose or wood pulp with fiber lengths up to 2 mm. The term nonwoven or non-woven also includes products which, in addition to textile fibers, contain a considerable proportion of cellulose or wood pulp, which are the material basis of paper manufacture. Such an admixture not only reduces the cost of a nonwoven, but the shorter cellulose and wood fibers also act as a kind of binding fiber for the longer textile fibers that make up the essence of the nonwoven.

The material basis for the textile fibers or threads contained in the nonwoven is also extremely wide and ranges from natural fibers such as cotton to cellulose, ie to Fiber converted cellulose, to synthetic materials based on polyester, polyamide, polypropylene and ganischen to anor ^¬ materials such as rock wool and glass fibers. Which nonwoven fabric is selected for the self-venting sack depends entirely on the goods to be filled, the packaging process and the devices used. However, it is precisely the large number of nonwoven fabric types and qualities on the market that, in addition to the easy and quick ventilation which is in the foreground, make the nonwoven fabrics extremely suitable as a material for a self-venting sack. A tailor-made nonwoven material is available for almost every need.

Of course, the high strength of these nonwovens is of considerable advantage, with those having a. Longitudinal and Querzugskraft dry between 80 and 400 Nm particularly useful ha¬ Ben and kgrößen for most fillings, the usual Sac ^'and sufficient filling weights.

As already stated, the wall of the self-venting sack does not necessarily have to consist entirely of nonwoven material, and it may be expedient to manufacture parts thereof, such as the filling or bottom area, from other materials for certain filling goods or stresses the wall of the sack, however, is at least half made of non-woven fabric in order to achieve the effect of rapid ventilation.

The very decisive advantage of the self-venting sack lies in the fact that it enables rapid venting, particularly in automatic filling systems, shorter cycle times and a higher degree of filling are possible. It is therefore preferably suitable as a valve sack. A preferred method for filling such a nonwoven sack is therefore that the filling is carried out with a delivery pressure of 0.8 to 1.0 bar and the sack can thus be filled faster and more densely. The rapid ventilation through the sack wall made of non-woven fabric

REPLACEMENT LEAF In particular, the refilling of the sack and a preferred process variant consists in shaking and / or tapping the sack after the first filling and refilling considerable amounts of filling material after this compression step, so that ultimately a full, the sack volume is fully filled results in a useful sack or, with the same filling weight as before, the sack can be kept smaller in its dimensions. This results in a filled sack that is easy to handle and easy to stack. These properties can be ended yet vervollstän¬ and improved when the filled sack after the filling and sealing in a further preferred Verfahrensvarian¬ te nor preferably on the broad flat ^sides' passed de.s bag engaging belts or -gepjreßt with press plates and so last air residues squeezed out and. the filled sack is given a largely rectangular, easily stackable shape that can be transported on pallets.

It is of considerable advantage that the self-venting sack according to the invention is also less problematic with regard to disposal and in relation to the environment. The valve bags made of paper, which have been customary up to now, usually consist of two paper and one plastic intermediate layer and cannot be reprocessed as a result, but must either be incinerated or disposed of in landfills and in this way pollute the environment. The sack according to the invention, on the other hand, since in its preferred embodiment it consists exclusively of non-woven material, can be broken down into the fibers, which can be processed into non-woven material for the same or another purpose.

The ^'non-woven bag allows a further particularly vorteil¬ embodiment of the invention in that it at the opposite end of the filling opening an N- expediently extend over the entire bag width extending fastener having the double function a. to enable easy emptying of the sack without having to cut away the actual closure, such as the valve area of the valve sack,

b. this results in the possibility of reusing the sack for the same purpose and thus

a considerable saving in the packaging material required overall for a certain quantity of filling material and a substantially reduced problem with regard to disposal and environmental pollution.

Two properties of Vlies.sto.ffes have a beneficial effect:

The good air permeability of the nonwoven facilitates the emptying of the filled sack, because no vacuum builds up as would occur with a conventional, needled foil sack. On the other hand, because of its textile character, the Vliesstόff sack is very well suited for sewing in such a fastener, preferably a fastener tape, and there is no risk of tearing or bursting.

The additional closure, which enables frequent reuse, can be a zipper known from packaging bags. A Velcro fastener is particularly preferred for its simple operation. The application is expediently already carried out during the manufacture of the self-venting sack.

This preferred further development of the invention and the attachment of the Velcro tape are shown schematically in a rough schematic diagram, without this further configuration of the invention to a reusable sack being restricted to this embodiment.

REPLACEMENT LEAF The individual steps in the formation of a reusable sack provided with a Velcro fastener are shown in FIGS. I to IV <3. The sack 1 made of nonwoven has a filling opening 2. In the case of a valve sack, this fill opening 2 would be closed by a valve closure with a lateral insertion opening for a filler neck.

The end of the bag 1 opposite the filling opening 2 has the tabs 3, 4 and 5, which are bent at right angles and glued or sewn together to give the bottom of the self-venting bag 1. The middle flap 3 of the one broad, somewhat elongated flat side ends in the sewn-on counterband 7, which forms the Velcro fastener in the filled state with the Velcro band 6 sewn on the other wide flat side in the lower region.

In the table below some nonwovens are listed with regard to their material composition, the type of bond, the weight per unit area, the thickness and air permeability as well as the fillers packed therein. All of these examples represent expedient designs. All valve bags could be filled at a filling pressure between 0.8 and 1 bar in 6 to 10 seconds with the filling weight given in the table without noticeable dusting. After tapping the filled sack, the contents could be compressed to the filling weight listed in the next column.

REPLACEMENT LEAF Filling weight Filling weight

Nonwoven fabric bond Weight Thickness of air through-fill in mm non-knocking without knocking with knocking base m ^< l / m ² / s in kg in kg (fiber type)

Cellulose

Polypropylene thermal 70 0.5 1470 12.2 18.3 powder (TAT 2547) 150 _/ u

Polypropylene thermal 100 0.6 750 12.5 18.7 (TAT 2602)

Viscose / polyester wet fleece 80 0.26 400 11.8 17.5 (PARABOND 11/80)

Viscose / polyester print - 95 0.6 250 13.4 16.4

(PARABOND 12/100) bonded

Polyester needled 150 1.0 900 grain meal 11.5 19.5 (TAT 25/47) 150 µm

Polyester spunbond 70 0.33 2800 cellulose powder. 11.4 16.5 (RK 70) thermal 75 / im

Polyester spunbond 70 0.33 2800 12.7 19.0 (RK 70) thermal

70% cellulose without

30% cotton binder 40 0.2 900 silica gel 14.2 22.0 (PARATEX 111/40) 20 ^ u

85% viscose print- 145 0.85 120 cellulose powder. 20.3 25.0

15% polyester bonded 75 / im (PARABOND 12/150)

Claims

1. Self-venting sack, for filling with finely divided fillings such as powders, grains, flakes, fibers, in particular fillings with a low density, characterized in that the sack consists entirely or partially of air and gas permeable nonwoven material, the air and gas permeability of which is so big that when filling. stagnant air or gases can escape through the nonwoven.

2. Self-venting sack according to claim 1, dadurh gekennzeich¬ net that the bag wall consists at least half of air and gas permeable nonwoven fabric.

3. Self-venting sack according to one of claims 1 and 2, characterized in that the nonwoven fabric has an air passage.

2 is 100 to 3000 1 / m / s.

4. Self-venting sack according to claim 3, characterized gekennzeich¬ net that the nonwoven fabric has an air permeability of ^ t00 to

2 2000 1 / m / s.

5. Self-venting sack according to one of claims 1 to 4, characterized in that the basis weight of the fleece

2 fabric is 30 to 200 g / m.

6. Self-venting sack according to claim 5, characterized in

2 net that the basis weight of the nonwoven fabric is 40 to 150 g / m.

7. Self-venting sack according to one of claims 1 to 6, characterized in that the thickness of the nonwoven fabric is 0.1 to 1.5 mm.

8. Self-venting sack according to claim 7, characterized gekennzeich¬ net that the thickness of the nonwoven fabric is o, 2 to 1.0 mm.

9. Self-venting sack according to one of claims 1 to 8, characterized in that the maximum pore size in the nonwoven fabric is 150 ^ m.

10. Self-venting sack according to one of claims 1 to 9, characterized in that it has a closure at its end opposite the filling opening for emptying the sack.

11. Self-venting sack according to claim 10, characterized gekenn¬ characterized in that the closure is a Velcro closure.

12. Self-venting sack according to one of claims 1 to 11, characterized. characterized in that the sack is a valve sack.

13. A method for filling a fleece sack according to one of claims 1 to 12, characterized in that the Befül¬ len takes place with a delivery pressure of 0.8 to 1.0 bar.

14. A method for filling a fleece sack according to one of claims 1 to 12, characterized in that after shaking and / or tapping the filled sack, a refill follows.

15. The method according to any one of claims IS to 14, characterized gekenn¬ characterized in that the filled bag duith rollers passed through and / or is pressed by pressing plates.