FR2555550A1 - SACK BAG WITH EXTENDED SIDE SHUTTERS AND METHOD OF MANUFACTURE - Google Patents

Abstract

THE INVENTION RELATES TO A PLUG-IN BAG WHICH INCLUDES A BAG WITH SIDE CLOSURES IN A THERMOPLASTIC FLEXIBLE MATERIAL WHOSE REAR PANEL HAS AN EXTENDED TAB WITH ONE OR MORE PERFORATIONS. ACCORDING TO THE INVENTION, SIDE-CLOSED MARGINAL EXTENSIONS OF THE FRONT PANEL OF THE BAG FACING THE EXTENDED TAB 16, THE LENGTH OF THESE EXTENSIONS EXTENDING THE SIDE SHOES 13 BEYOND THE MOUTH OF THE BAG 17, SUFFICIENT FOR THE LOADING HANGING OF A PRODUCT IN THE BAG, WHILE IT IS PLUGGED, THE LOADING FORCES ACTION PLAN CUT THE SIDE CLOSURES SENSITIVELY BELOW THEIR EXTENDED TERMINATION POINTS. THE INVENTION APPLIES IN PARTICULAR TO PACKAGING.

Description

The present invention generally relates to packaging bags made of

  plastic plug, and it relates more particularly to the plug-in bags

  with lateral fillings having an extended tongue.

  Lateral sealing bags are traditionally made in series from a flat tubular film, splitting a flattened edge of the tube flat and heat sealing the tube at regular intervals.

  transversely by pairs of thermal seals or ob-

  juxtaposed turbulence and a line of weakness between them. The split edge of the tube forms the mouth of the bag while the transverse joints or fillings form the sides of the bag. When producing a series of extended tab bags, a longitudinal strip along one face of the flat tube is removed near the edge of the

  tube which must be the end forming jaws of the bags.

  Such bags thus have a shorter front panel than the back panel, so the mouth of the bag is at the upper edge of the shorter front panel of the bag. Punctures are formed in the extended tab of the bags so that a number of these bags can be stacked on stakes to facilitate the loading of the product into the bags. Loading the product using plugged bags typically includes the steps of providing a pile of bags plugged on stakes at a loading station of the product and then directing an air stream to the mouth end of the highest bag for inflate it, then a

  product is inserted into the inflated bag at a sufficient force

  health to tear the bag of stakes, tearing occurring at perforations. This sequence is repeated for a series of products until the stack of bags

plugged in or out.

  Sacked bags with lateral fillings present a significant problem regarding the integrity of the lateral fillings during loading of the product. The end points of the lateral fillings at the mouth end of the bag are relatively low and when a product is thrown into an inflated bag inflated, forces are imposed on the mouth of the bag which tend to delaminate the lateral fillings at the end of the bag. relatively weak points of termination before the bag is torn from the pegs. It should be noted that the above problem does not appear when using lunch bags to

  seal or extreme obturation. An attempt to surpass

  to overcome this problem is to provide slits initiating the tear at the apices of the perforations. However, this attempt has the disadvantage of causing critical problems in the bag separation device where a perforated series of such bags is separated into individual bags. The present invention is directed to the integral strengthening of the terminations of fillings

lateral of such bags.

  The disclosure of US Pat. No. 3,372,857 entitled "Side Seal Bag Construction with Stress Relief Notch" dated March 12, 1968 to Brayla is of general interest, being directed to an extended-tab plug-in bag.

  and lateral fillings, having stabilization notches

  thermofusion near the endings of the ob-

  Lateral rations end mouth side to prevent delamination of lateral fillings during loading

  of a product in the bag while it is plugged.

  The disclosure of US Patent No. 3,804,322 entitled "Plastic Bag Having Arcuate Closed End and Arcuate Lipped Open End" of April 16, 1974 in the name of Ericson is of general interest, being directed to plugged bags with extreme obturation having a mouth end arched and an arcuate cutout in the front panel of the bag opposite the perforations in the back panel of the bag. The configuration forms marginal ears at the end

  side mouth of the bag sealed at the end for a gathering

  the mouth of the bag after loading the

product.

  The present invention relates to a plug-in bag with extended tab and side fillings, having side fillings integrally reinforced in the area of the jaws of the bag so that during the loading of the product, the bag tears preferentially to the perforations rather than at the end points of the lateral fillings. Accordingly, there is provided in a plug-in bag comprising a flexible thermoplastic side seal bag with its back panel having an extended tab containing one or more perforations, narginal side-closure extensions of the front panel of the bag facing the extended tongue,

  the length of the extensions extending the lateral fillings

  beyond the jaws of the bag sufficiently so that during the loading of a product into the bag while it is plugged in, the action plan of the loading forces cuts off the lateral fillings substantially beyond

extended endpoints.

  In a preferred embodiment where the plug-in bag has two symmetrically-located perforations, the plane of action of the loading forces is substantially in a plane defined by first and second points at the apices of the perforations respectively, the perforations being spaced apart by their separation flat and a third point in the center of the edge of the jaws of the bag when the mouth is fully extended and the

  bag is retained at the first and second points.

  Preferably, the extensions of the fillings

  sides extend from the jaws of the bag at least until

  than at the peaks of perforations, and better up to the top

of the extended tongue.

  In addition, there is provided a method of manufacturing an extended tab and side seal insert bag which consists of forming a mouth-side cut in the front panel of the bag to partially expose the rear panel of the bag to form a extended tongue and marginal and opposite extensions of the lateral fillings in the front panel of the bag; and forming one or more perforations in the extended tongue, which are selectively placed so that during loading of a product into the bag then

  that it is plugged in, the action plan of the charging forces-

  cuts off the lateral fillings substantially above

  endpoints thus extended.

  The invention will be better understood, and other purposes, features, details and advantages thereof

  will appear more clearly during the description

  explanatory text which follows with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which: FIG. 1 shows a plug-in bag

  extended tongue and lateral fillings according to the invention.

  tion, which has marginal extensions of the lateral fillings at the mouth-end of the bag on the front panel of the bag; FIG. 2 shows a special case of the embodiment which precedes the extensions of the lateral fillings extend to the top of the extended tongue on the rear panel of the bag; and FIG. 3 schematically illustrates a diagram of the loading forces of the bag of FIG.

  in plugged and inflated configuration.

  Figure 1 shows a plugged bag 10 extended tongue and side fillings according to the invention. The bag 10 has a front panel 11 and a rear panel 12 joined at their edges by lateral heat seals 13a, b. The side seals or closures 13 are spaced from the width 14 which defines the width of the envelope of the

  bag 10 containing the product. The bottom 15 of the bag is possibly

  seamlessly as shown, for example when the bag is formed of a tubular film

  flat. The rear panel 12 has a longer length

  aunt than the front panel 11 so as to obtain the extended tongue 16. The mouth 17 of the bag is spaced in

2555,550

  below the top of the tongue extended by a distance 23 which is the height of the tongue. Thus, the length of the envelope of the product-containing bag 10 extends from the mouth 17 to the bottom 15. The extended tongue 16 is pierced with a pair of perforations 18a, b located symmetrically across the bag , and whose centers are spaced from the distance 19. The bottom of the perforations 18 will usually be at or above the mouth 17 of the bag so that the front panel 11 does not interfere with

  the insertion of the stakes through the perforations 19.

  Optionally, although not preferable, the perforations can be drilled to pass through the mouth of the bag in the front panel so that the bottom of the perforations is below the edge of the mouth a short distance, for example reaching about the radius of the perforation. The apices of the perforations are spaced below the apex of the extended tongue

16 from a selected distance 20.

  According to the invention, the bag has marginal extensions of the lateral fillings 21a, 21b which extend, on the sides, the front panel 11 upwardly from the mouth 17. The length of the extensions 21 must be greater than one. minimum critical length as will be better described below, but according to a preferred empirical method, will extend to or above the apex of the perforations 18, i.e. the space 22 will preferably be approximately equal to or smaller than the space 20. Optionally, the extensions 21 may extend to the top of the extended tongue 16, as will be better described below. The width of the extensions 21 is indicated at 24 and in general, it will be sufficient to allow the lateral fillings 13 to be formed along the marginal extensions 21 without difficulty. However, the width 24 of the extensions will not be large enough to interfere with the perforations. Preferably, the width 24 of the extensions is greater than the zone affected by the heat near the seal 13 to reduce wrinkling and thus improve the flattening of the bag. Typically, the

  Width 24 of the extensions will be at least about 6.35 mm.

  The marginal extensions with lateral fillings 21 are intended to extend the lateral fillings of the bag beyond the jaws of the bag at least over a certain critical distance so that during the loading of the product into the bag with the plugged-in configuration, the loading forces do not act significantly on the relatively weak points of termination of lateral fillings. Therefore, while loading the

  product, the bag is torn preferentially

  rather than at the termination points of closure

  side effects. Preferably, rounds 23 are provided at the junction between the marginal extensions and the

  jaws of the bag for a stabilization of the constraints.

  In Figure 2 is illustrated a preferred embodiment of the invention which shows a kind of bag 10. The bag 50 is similar to the bag 10 in all respects except that the marginal extensions 51a, b with lateral fillings extend completely from the mouth of the bag 52 to the top of the tongue extended at 53. This arrangement is preferable to facilitate the manufacture of the bag and can be simply formed by forming a conventional bag with side fillings from a flat tubular film as we have

  described above and then producing a cut-out at the

  In the front panel of the bag, the cutout is generally U-shaped. Punctures are then formed in the thus exposed portion of the back panel of the bag, i.e. the extended tongue, and are selectively placed. relative to the endings of the lateral fillings according to the invention. Preferably, a perforated series of such bags is formed by first obtaining a flat tubular film of indefinite length, slitting a collapsed edge of the film flat, cutting on one side and at regular intervals on the length of the flat film, U-shaped cuts at its split edge, piercing perforations selectively placed in the area exposed by the cut, and at regular intervals between cuts along the flat film, in forming pairs of transverse thermal joints juxtaposed with a perforated line of weakening them. The bag of Figure 1 can be made in a similar manner with the exception that the cutout has the shape of a winged U as can be seen. For ease, the side heat-sealing cords can be taken at the top of the extended tongue over the extensions of the

lateral fillings.

  In Figure 3, a side view of the bag 10 of Figure 1 can be seen in the inflated and plugged configuration 10A to illustrate the loading forces of the product acting on the mouth of the bag and to illustrate the principle of the invention. The bag is plugged onto stakes (not shown) by means of perforations 18a, b respectively, and an air jet is directed into the mouth of the bag to inflate the bag as illustrated to facilitate the insertion of a product. , like a whole bird, in the bag at a loading station. The bag is retained by the pegs, the center of the perforation 18a being indicated at 30, the holding point being the vertex

  perforation applied against a post at point 31.

  The inflation of the bag while it is retained at its perfor-

  The diaper dilates the bag so that an expansion above the lateral closure 13 indicated at 32 is approximately equal to half of the space 14, i.e. the space between the lateral fillings. while below the lateral closure 13, the expansion of the bag indicated at 33 is approximately half of the space 14 minus the space 19 between the perforations. The point 34 indicates the center of the mouth of the bag or the highest point of the mouth of the bag in the inflated state which will be the main point of contact when pushing an S

  produced in the inflated bag. Thus, the charging forces-

  The product will act on the mouth of the bag substantially at point 34 with the reaction forces at point 31 being the point of retention of the perforations against the stakes, respectively. Line 35 represents the line of action of the loading force that cuts

  the lateral closure 13 near the location 36.

  Line 35 is better characterized as a plan of action of loading forces. Location 36 will be located

  at a small distance below the top of the perforations

  The principle of the invention then lies in the fact that the loading forces act on the lateral fillings of the bag in an intermediate zone away from the relatively weak point of termination of the closure at 37. If the plane of action had to pass through point 37 or to the right of point 37, then the lateral fillings of the bag could peel or

  delaminate while loading the product.

  It should be noted that in the general case, the line or the course of action of the loading forces and its intersection with the lateral fillings are easy

  to be determined by visual observation. Such a determination

  nation is simply implemented by first arranging a test bag in flat condition on a substantially flat surface and then holding the bag at the tops of its perforations against the surface, and then completely extending the mouth of the bag roughly in the center of the edge of the mouth. At this extended and slightly stretched configuration, the lines of stiffness are clearly visible and the distribution of the relative degree of stiffness is easy to discern to the touch. Therefore, the location of the intersection of such lines of stiffness with the lateral fillings can easily be seen. The loading forces action plan is considered to be approximately coextensive with the maximum stiffness line and the action plan is considered to be substantially below the termination of the lateral closure when stiffness or distribution constraints around this plane are almost zero at the endings. As a preferred practical empirical method, the marginal extensions of the lateral fillings 21 must extend from the jaws of the bag approximately to the apex of the perforations at point 31. As can be seen in the diagram, when this condition is fulfilled, the action plan of the loading forces passes

  below point 37, that is the point of completion

  naison of the lateral fillings at the top of the extensions.

  However, as can be seen in the diagram, the minimum critical extension length will be somewhat smaller than the apices of the perforations. As a first approximation, the minimum critical extension can be determined by the following equation, determined from geometric deductions and by modeling the lateral closure as a radius on an elastic base: X = D - b Fl + ((D / b) - 1) (ca) / (2c-a)] + 1, 8 (Ewh3 / K) in which, X = length of the minimal critical extension of the lateral fillings; a = space between centers of the perforations, b = space at the top of a perforation at the top of the tongue; c = space, in width, of the bag between lateral fillings; D = space of the jaws of the bag from the top of the tongue; w = width of the side weld seam; h = thickness of the lateral obturation; K = elasticity constant of the film (which will be described better below); and

  E = modulus of elasticity of the film.

  To illustrate the use, for the calculation, of the above equation, consider a side closure bag constructed according to Figure 1. The bag is partially characterized by geometric parameters including a diameter of 15.87 perforation mm with a space between the centers of 76.2 mm (a) and with the top of the perforations spaced from the top of the extended tongue of 33.27 mm (b). The width of the bag between the lateral fillings is 216 mm (c) and the mouth of the bag is 50.8 mm (D) below the upper edge of the extended tongue, that is to say just below the perforations in practical goals. The lateral heat seals of the bag are characterized by parameters including a cord width of 1.47 mm (w) and a thickness of 0.127 mm (h). The thermoplastic film whose bag is made is characterized by the film parameters including a film thickness of 0.0508 mm, a modulus of elasticity of 231.6 x 106 Pa (E) and a film elasticity constant. 1.267 kg per cm per cm (K). The elasticity constant of the film is defined as the thickness of the film multiplied by the tensile force applied per unit volume of the test film which is subjected to the force divided by the tensile strain which results. From the equation above, the critical extension of marginal extensions to lateral fillings from the mouth of the bag is calculated to be 13.46 mm (X). It should be noted that this critical interval places the extension between

  the top of the perforation and the center of the perforation.

  At this point, there is essentially no tension on

  the termination of the lateral obturation. When the ob-

  lateral ration is completed at or beyond an extension of approximately 13, 46 mm, then the risk of a rupture of

  shuttering due to the loading forces are sensi-

decreased.

  As an example of use, bags of the type illustrated in FIG. 1 have been tested for a failure of side fillings under simulated conditions of loading of a plugged bag, as shown in FIG. depending on the length of the extensions of the lateral fillings. The test process consisted of (1) holding a bag at the tops of its perforations, (2) pulling the mouth of the bag down at its center and at an angle of about 45 from the back panel of the bag, using an elastic scale to observe the values of the applied force; and (3) continue to pull until the test bag breaks in a certain way and then note the failure mode and breaking force. The various modes of rupture are the tearing of the lateral fillings from the mouth-end endings, the tear of the tongue extended to the perforations, the tearing of the front panel of the bag and

the tear of the back panel.

  The test bags were characterized by geometric parameters including a total length of 355.6 mm, a diameter of the perforation of 15.87 mm with a space between centers of 76.2 mm (a) and spaced from the top of the extended tab of 23.87 mm (b), a width of the bag between the lateral fillings of 165.1 mm (c), and a space of 44.45 mm (D) of the mouth compared to the top of the tongue extended. The lateral heat seals were characterized by parameters including a weld seam width of 0.711 mm (w) and a thickness of 0.254 mm (h). The thermoplastic film of the bags was characterized by film parameters having a film thickness of 0.051 mm, a modulus of elasticity of 231.6 x 106 Pa (E) and a constant

  elasticity of the film of 0.703 kg per cm per cm (K).

  The film was a four ply barrier film generally of the type disclosed in US Pat.

  No. 3,741,253 of June 26, 1973 in the name of Brax et al.

  The critical length of the plugging extension

  Lateral was calculated using the equation above.

  as being 17.78 mm (X). Bags were tested near and below the critical extension length. The

  The results are given in the table below.

TEST GROUPS

  Extension of lateral fillings in percentage of critical extension

(A) (B) (C)

% 70% 90%

  Number of bags tested 254,298,204 Number of bags breaking by lateral sealing 97 48 2% of total 38 16 1 Strength (Newton) at break, average 57.38 58.27 80 Standard deviation of breaking force 11,56 10,67 From the above table, it can be seen that the test group A having a length of the extension of

  the lateral filling represents approximately 40% of the ex-

  Critical tansion had a high failure rate in lateral closure failure mode of about 38%. Test group B having an extension length approximately equal to 70% of the critical extension had a substantially reduced rate of lateral closure failure of about 16%. In group C, the extensions of the lateral fillings were very close to the critical value and showed a rate of fracture of the lateral closure dramatically reduced by about 1%. Thus, it can be seen that a dramatic decrease in the rate of failure of the lateral closure occurs while the extension of the lateral closure approaches the critical value. Moreover, it can be seen that the breaking force Lateral obturation increases dramatically from Group B to Group C.

Claims (14)

R E V E N D I C A T I 0 NS   1.- Plug-in bag comprising a closure bag   lateral arrangements of thermoplastic flexible material whose rear panel has an extended tongue with one or more perforations, characterized in that it comprises lateral extensions with lateral fillings of the front panel of the bag which face the extended tongue (16), the length of said extensions extending said lateral fillings (13) beyond the jaws of the bag (17), sufficiently so that during the loading of a product into the bag, while it is plugged in, the action plan of the forces of Loading cuts off the lateral fillings substantially below the extended termination points. 2. Bag according to claim 1, characterized in that the extensions extend at least until top of the perforations (18).   3. Bag according to claim 2, characterized in that the extensions extend to the top of the extended tongue.   4. Bag according to claim 1, characterized in that it comprises two symmetrical perforations, and in that the aforesaid plane of action is substantially in a plane defined by first and second points to   vertices respectively, said perforations   rations being spaced by their separation flat, and a third point in the center of the edge of the mouth of the bag when said mouth is fully extended with said   bag retained at said first and second points.   5. Bag according to claim 4, characterized in that the extensions extend at least to a critical extension determined by the following relationship: X = D - b Â1 + ((D / b) - 1) ( c - a) / (2c - a)] + 1.8 (Ewh 1/4 in which X: length of the critical extension of the lateral fillings: a: space between the centers of the perforations; b: vertex space of a perforation at the top of the tongue; c: width of the bag between the lateral fillings; D: space between the jaws of the bag and the top of the tongue; w: width of the cord of the lateral closure; h: thickness of the obturation K: elasticity constant of the film, and   E: modulus of elasticity of the film.   6. Bag according to claim 1, characterized in that the width of the extensions is sufficient to exceed the region affected by the heat around the lateral fillings.   7. Bag according to claim 1, characterized in that rounds of stress stabilization are   provided at the junction of the extensions with the jaws of the bag.   8.- A method of manufacturing a plug-in bag with extended tab and side fillings, characterized in that it consists in: forming a cutout at the end side mouth in the front panel of the bag to partially expose the back panel of said bag to form a tongue   extended with marginal and opposite extensions of ..   lateral fillings in the front panel of the bag; and forming one or more perforations in the extended tongue, which are selectively positioned so that during the loading of a product into the bag while it is plugged in, the action plane of the loading forces cuts off the lateral fillings substantially   below the points so extended termination.   9. A process according to claim 8, characterized in that the aforesaid cutout is formed generally according to a winged U.   10.- Method according to claim 9, characterized in that the aforementioned perforations are placed so that their vertices are at or below   from the top of the extensions to lateral fillings.   11. A process according to claim 8, characterized in that the aforesaid cutout is formed generally U-shaped. 12. A method according to claim 8, characterized in that it consists in forming two symmetrical perforations, and in that the aforesaid plane of action is substantially in a plane defined by the first   and second points to the vertices of the respective perforations   said perforations being spaced apart by their separation flat, and a third point in the center of the edge of the mouth of the bag when said mouth is fully extended with said bag retained at said first and second points.   13.- Method according to claim 12, characterized in that it consists in forming the above-mentioned cut and positioning the aforementioned perforations so that the aforementioned extensions extend at least to a critical extension relative to the apices of the perforations as determined by the following relationship: X = D-bl [1 + ((D / b) - 1) (c - a) / (2c - a)] + 1.8 (Ewh3 / K) 4 in where X = length of critical extension of lateral fillings; a = space between centers of the perforations; b = space at the top of a perforation at the top of the tongue; c = width of the bag between the lateral fillings; D = space of the mouth of the bag at the top of the tongues w = width of the lateral weld bead; h = thickness of the lateral obturation; K = elasticity constant of the film; and   E = modulus of elasticity of the film.   14.- Method according to claim 8, characterized in that the aforementioned marginal extensions have a greater width than about the region   affected by heat around the lateral fillings.