CA2032699A1

CA2032699A1 - Assembling device to form a releasable bond between adjacent surface elements and method for manufacturing this assembling device

Info

Publication number: CA2032699A1
Application number: CA002032699A
Authority: CA
Inventors: Hans Dieter Flieger
Original assignee: Individual
Current assignee: EIDP Inc
Priority date: 1989-12-21
Filing date: 1990-12-19
Publication date: 1991-06-22
Also published as: AU6827890A; DE69019701D1; HU213588B; PL165182B1; DK0434447T3; CZ647890A3; EP0434447A1; JPH04119209A; HUT58637A; JP2588372Y2; DE69019701T2; JPH0745071U; ES2072402T3; PL288400A1; AU632192B2; EP0434447B1; HU908411D0; ATE122983T1

Abstract

ABSTRACT OF THE DISCLOSURE

An assembling device for forming a releas-able bond between two adjacent sheets comprises male and female elements. At least one of the sheets is embossed to form the male element, which has a closed periphery. The device can be used on a bag which can be opened and closed tightly again.

Description

l ~d~

ASSEMBLING DEVICE TO FORM A RELEASA~LE BOND BETWEEN
ADJACENT SURFACE ELEMENT5 AND METHOD FOR MANUFACTURIN~ THIS

The present invention concerns an assemblinq device tQ
Eorm a releasable bond b~tween two adjacent s~rface elements comprising at least two eonnecting members, respectively, one male ~nd one female, ~l~c~d in facing r~lation ~o each other for reciprocal ~ngagement when said surface elements are assem~le~ together; the invéntion also eoncerns a method for manufacturing the device.
T~ere exist.s a~r~acly a largc n~mber of ~eviccs ~f the aforementioned kind, namely in the field of packaqinc3. All the closinc3 dcvices of thi 5 kind to be used in ~ackaging and which can be opened and closed again at will to protect the content of the package frDm thc outsic~e atmosphere comprise connecting members which are either extruded simu~taneously with a wrap-per film or sheet, or they are first injection molded and thereafter fixedly bonded to the wrapper sheet or film by glueinc3 or weldin~.
~ hen the c~nnecting members ar~ co-extrucled wi~h the sheet or film, these connecting members are formed of inter-joining ribs provided along the edges of the sheet which is thereafter folded tn pl~ce the joir~in~ members in mut~al registration. The folded sheet is th~n welded transversslly to form bags which are then separated from each other by split-tinc3 along the transYersal welding lines. I~ well known clos~re system ean be formed only during extrusion of the sh~ct. Because of overthiekness due to the ribs, it is dif~i-cult to store the material ln the form of larqe rolls. This is because the volume of a roll with ribs, ~iven a length of film or sheet, i5 ~ubstanti~lly gr~ter than the corr~s~on~in-3 volume of a same len~th of film nr sheet taken alone without ribs. 11ence for puckin-3 ~he pack~r h~ ~1ifEicul~y 1naking the bags starting from ~hc sheet material and thus has to use individuai prefabricated b~gs. This is the reason why general-ly 5l1C~ ~a~s are no~ s~l for con~lit:ion~(1 p,1ckinq, because they arc not well stli ted to automa~;ion for wh~ch On~! ~r~fer-2 ~ D, ',~

ably uses sheet wrapper material and Airectly form ha~Js aronndth~ roduct ~o ~ pack~ged.
This is why the sl~b~tances to be pro~ected from air .Ind moistllre are packa~ed in sealed bags with welded ~oints. This type of closlJre enahles to safely store the conditioned produ~ts until the bag is o~ened. From there on, since this type of hag cannot be closed tight a~ain, many of the lJncon-sumed products will no longer be protected and may rapidly de~rade. It is a fact that:, un~il now, a cheap and simple solution to this problem, to b~ implemented with li~ht and efficient technical means, did not exist yet.
An object of the present invention is precisely to dis-close a solution of this sort.
For doing this, the present invention has for an object an assembling device for forminq a releasable bond between two adjacent surface elements according to claim 1. It has also for an object a method of manufacturing this device according to cl~ims 15, 16 or 19.
The main advantage of this assembling device resides in its manl~facturing convenience, ~iven that it can be hrollght about at any time from a simple film or sheet material without re~uiring additional material. For instance it can be formed simllltaneously with the manufacture of the films or sheets or it can be formed at a la~er opportunity; this enables to make for instance a bag whi~h can be opened and closed tight again during packaging of the product, this ~eing without imposing production costs exceeding that of an ordinary ba~ with a wclded joint of the ~y~ s~d until now. Since the sheet is not lucally ~verî;hi~herlod ~nd the eorlnet~ing momhars erlga~e reciprocally with one another, the sheets in which the con-necting memhers are formed can easily be stored into rolls.
Naturally, as ~ill be seen hereafter, the use of the assem-blin~ ~evioe is not Iimi~ to the seaIing of hags.
I~e accompanying drawin~ illus~ra~e: schemat~cally and by way of example several variants of the assembling device which i5 an object of the present invention.
Fig. 1 is a perspective view of an embodimen~ of this a 5 ~em~ling device.

3 ~ r~ ~

Fig. 2 i~ a perspective view of a var1ant of fig. l.
Fi~. 3 is a perspective view of another variant of fig. l.
Fi~3. ~ is a cross-sectiona1 si~le view of the ~rofile of the sealing members of the assembling device.
Fig. 5a ~nd 5h are cross-sectional side views of another variant of profile of the sealing members shown in disassem-bled ilnd ass~mbled condition, respect:ively.
Fig. 6a and 6b are ~ross-sectional side views of another variant of profile in the sa~e position as in fig. 5a and 5b.
Fig. 7 is a view in perspective of still another variant of this profile.
Fig. 8 is a perspect~ve view w~ich illustr~tes an application of a closing device for a non-flexible container.
Fig. 9 is a cross-sectional view of a variant of the connectin~ members of the device.
Fig. lO is a perspective view of still another variant of the device.
Fig. lla and llb are cross-sectional side views of a last variant of profile of the sealing members shown in disassem-bled and assembled condition, respectively.
Fig. 12 is a pers~ective view of one particular use of the device.
The assemblin~ devi~e illustrated in fig. l comprises male and female connecting mem~ers, l and 2 respectively, of ~ilms or sheets, respc~tively 3 and 4, l:o be assembled to~e~her. ~c sheet 3 is ~rovi~eA wlLh a row of ma~e sonnect-ing members l and the sheet 4 is providc~ with a row of female eorlnectin~3 memhers 2. 'l'~)e ~ tarlcu ~h~t se~rat~s, 1rl ~ row, the m~le conn~c~in~3 melnl)er~ corr~u~or~ o ~h~L ~lu~nc~ w~lch separates the female conneeting members. As can be secn from this example, the male and female connecting memhers, l and 2 respectively, are formcd by shaping or embossing the sheets 3 and ~, respectively. Preferably, the sheets are of thermofor-mable polymers and embossing is preferahly achieved by hot-~orming using metho~s to be discl~ed hereafter in more detail. The sheets 3 an~ 4 ~an ~e thin, i.e. between 40 and lOO llm. It has heen not~d that it is preferable that the connecting members 1 and 2 have complementary cross-sectional dimensions whi~h mate to~ether and fit into each other. ~hen th~ surfaces are ~eparated, the sheets 3 and 4 are withdrawn from each o~her with ~equentlal disen~agement of ~ale and female connectors. During disengagement, the male and female connecting me~bers are subje~t to strain and deformation ln the plane of the sheets which puts t~em out of alignment and results into a wed~ing effect be~ween ~he respective side surfaces of said connecting members whieh resists. to the disengagement. This effect reinforces the retaining back pres-sure effect which res~lts from the disconnecting pull. The combined effects explain why the binding strength of the assembling device is so effective. This assembly of the two sheets along the row of connecting members is also sufficient-ly tight to provide, under ambient pressure, a barrier appro-priate to protect the content of a bag for instance from the influence of the outside.
In this disclosure, the term of "sheet" should be under-stood as including all more or less flexible materials of any given thickness.
The resistance of the assembly t~ separati~n nf the sheets and also the sealing eapacit;y through the line of connecting means can be increased by plAcing, as illustrated for instance in fig. 2, twn rows of connectin~ m~ans 5 and 6 in parallel, t.he connect.ing memhers of a row being staggered relative to t;hat of another row. The total rubbing surface ls incrcased, hence the force for separ~ting sheets 7 and ~ from each other is also increased. The connecting members of rows 5 and 6 are also ~iverl a rectangular form, so the tightne~s is improved due to the st~3~ered configuru~ion.
Obviously 'the assembling device d~es not pravide full air-tightnes~ and it curJ be desirabl~ in some cases to achieve impervious seals, namely for vacuum packaging. For this, the t:wo sheets 3 and ~ forl~n~ a ba~ can he s.e~le(l by a we~ding S
externally to the line of connecting members; these members can be identical to that with reference numerals 1 and 2 ln fig. 1 for example, and in parallel thereto. T~ op~n the ~ag, the sheets 3 an~ 4 are cut between the weldin~ line S and the ~ $?~

line of connecting members 1 and 2, wh~h gives access to the lnside of the bag; afterwards, the bag can be closed a~aln using the connectin~ mem~ers, the content of the bag being thus preserved until entirely used up.
The variant illustrated in fig. 4 comprises male and female connect~ng members, 9 and 10 respectively, having a frustDconical or frust~pyramidal shape. In this variant, the bindin~ elements can preferably be used in combination with a pressure sensitive a~hesive ~o be coated on the ~oining surfaces of the male and female sealing members 9 and 10. An adhesive ~f this kind can be, for instance, an ethylene/vinyl-acetate copolymer such ~s Elvax sold by the Du Pont Company.
~ ig. 5a and 5b ill~strate a variant in w~ich the female connecting member is formed by an opening ll provided in a wall 12 whose thickness is greater than that of the embossed sheet 13 including the male connecting members 14. The front of each connectin~ member 14 is proviAed with a ring-like flange 14a whose transverse cross-secti~n slightly excee~s the size of the opening corresponding to the female member 11. The distance between the flange 14a and the surface of the sheet 13 which carries the male members 14 corresponds substantially to the thickness of the wall 12, hence when the connecting members are in mesh after pres5ing sheet 13 against wall 12, the flange 14a which was temporarily deformed when passing throllgh openin~ 11, rests against the surface of the wall 12 some distance away frnm the surf~ce whi~h is aAjacent to that of sheet 13, as shown in fig. 5b. This mode of assembly evi-dently improves the resistance toward separation of walls 12 an~ 13 since the locking action is no longer the result of frictional resistance but is due to ~rippin~ of the male element 14 into the female element 13.
In the variant lllustrated in fig. ~a, 6b, the assembling mode of sheets 15 and 1~ i5 nearly i(lentical w$th t,hat of fi~.
Sa, 5b; the only ~ifference concerns the thickness of sheets an~l 16 which is the s~me for boLh, i.e. in the order of about 40-100 ~m. In order that the axial length of the opening 17 forming the female securing member be qreater than the sheet thickness, this sheet 16 is stamped to provide a wall ;$ 9 ~

16a aligned with the openinq 17 obtained by punching.
Thereafter, when the male securing member 18, which is identi-cal with that shown by reference numeral 14 ln fig. 5a, 5b, ls sna~etl lnto t.he n~enlntl 17, it,s annu~flr flanqe l~a lncks itself at the outlet of the channel formed by wall 16a.
Yarlants of fig. Sa, 5b, 6a, 6}~ can be of parti~ular interest for p~ckaying product5 in powder form. This is so because when a powder is taken from a bag, some can penetrate into the hollow female connecting mem~ers o~ the kind 11-lustrated in fig. 1 and 3 and hinder subsequent closing of the bag; in the case of openings shown in fig. ~a and 5a, the pow~er can no longer fill the female imprints. Having an openirlg 11 with n~ su~4~rate deform~jon can ~150 he of inte-rest when the sheet or wall 12 is of a non-therm~formable mate~ial, i.e. a relatively rigid material.
The variant of fi~. 7 ill~lstrates the fitting of a cylin-der-shaped male element 19 into a polygonal-shAped cross-sectional print 20, a square in this example, forming the female member. Using connecting clements in which the shape of the male members is different from that of the female members can facilitate the evacuation of the air upon pressin~ the members together. Naturally for this, the female member could also be shaped cylindrically and the male member have a poly-gonal cross-section fitting into the female circle. In the two mo~ifications of this variant, the re~pective size of the ~ransverse cross-sec~ior~ oth male ~n~l f~male conrlectin~
means will be selected to ensure that some deformation thereof be achieved upon f itt,inq the two toqether.
Naturally, the use of the foregoin~ assem~ling device is not ~imited to closirlg bugs but can he adapt,ed to other kin~s of containers as illustrated for instance in fi~. 8 in which there i5 shown a tray 21 with a rim 22 in which there are formed a plurality of openings 2~ which function as the female connectin~ members of the assem~ling device. Ther~ i5 alB0 provided a shee~ 24 for closing the tray 21 w~lose edge i 3 embossed to for~ male connecting members 25.
Since the matins of ~he male and female connec~ing mem-bers requires some force, the thickness of the sheet use~ for _ . _ . .. . . _ 7 ~J'~ 9 .

forming the male embossments must be sufficient to resist the effort. If the material of the sheet is too thin, it~ resi-stance can be enhanced by folding the sheet Z6 on itself in t.he area where the conrle~ting memhers are forme(l ~s showrl in ~ig. 9.
As indicated previously, at least the male connecting members are formed by embo55ing the sheet material which is essentially of thermoformable polymer. The simplest ~ethod to achieve embossing include~ heating the area to be raised to forming temperature, placing this area in re~istration with a stamping matrix havin~ in negative the shape of the desired relief, subjecting the sheet to depression on the ~atrix side of the sheet, this depression being suffi~ient to ~rive the softened sheet material into the hollow print in the matrix, cooling the area of the formed sheet and removing it from the matrix. This method is simple and ~ast. In some cases, the suction which drives t;he softened thermofnrmable material into the matrix prints can be replaced by using a punch which deforms the material and drives it into the matrix.
The female connecting means can be ~ade similarly in the cases of the variants of fi~. 1 to 4 and 7; in the case of the variant of fig. 5a r the opening i5 punched; in the case of fig. 6a, the opening can be stamped, i.e. deformation and punching can ~e carried out simultaneously.
I~ is also p~ssil~le to combine different formin~ methods to makc the pr~sent oonnectin~ mem~ers, fnr inst.ance comhinin~
vacuum forming and die stamping.
Also, accordin~ to another variant, the embossed connect-ing elements can be macle by cold forming of a deformable sheet material.
Naturally, the assembling device disclosed here need not be limited to using sheet materials for forming bags or tray lids for instance as illustrated in fig. 12. The elements of the device to be assembl~ can be in the form of a strip 31 whose width only ~ htly exceeds that: of the embossed area, the strip ~eing thereafter welded or glued to a surface 32 to be joined to another one. For instan~ a paper hag can be provided with a system of this kind.

~ ;3 The strip element carrylng the female connecting members can be ak~n to the striE) 31 the ~ur~a~e on which it is to be glued being first punche~ with holes. This strip element carryiny the ~e~e memhers c~n .1lso h~ m~l~e~ from a s~rip with thickness greater th~n t~lat of ~trip 31. Finally, a system is al~o possible in w~ich the male members in a strlp match with simple openings in a sheet, like the openings ll $n fig. 5a which are directly cut into the surface to be reci-procatingly assembled to the ~ale membered ~trip.
The sheet material to be used for making at least the male connecting members is either in single film form or in multilayer form, i.e. comprising several polyolefin layers in combination wi~h anoLher ~r more differen1 pc)lymers. 1~ to now, the embodiments of the assembling device have been repre-sented as comprising a plurality of binding members aligned in the fcrm of at least one row. In other cases one may have only one continuous long male member 27 which fits into a comple-mentary female member 2~ as illustrated in fig. lO. The catch-ing action of said elements 27 and 28 toward one another results from the shape of their cross-sectional profile which is provided with a narrowing. The presence of a narrowing requires that the profile be temporarily strained upon reci-procal engagement or disen~agement.
In the Yariant of fig. lla and llb, the male and female el~menl:s, respectively ~ and 30, are com~lementarily shaped ~nd forme~ of circ~lar cr~q3-sectional ele1nents w~h ~ frusto-conical section ~9a, 30a. When the mushroom shaped stud 29b of the male member 29 is applied against the socket ~Oa of the female element 30 in order to make ~t snap into it, the pres-sure md~es the tip ~Oh to shrink and ~ass thr~gh the bottle-neck 30c of the female element in order to cnme into its meshed state as illustrated in fig. llb.
It is possible to combine any of the foreyoing variants with a heat-reactive adhesive which enables to eventually separ~te the assemble~ surface element~ by peeling off at least the surface element ln form of a sheet or film. This type of closure is generally known as a "peel-seal" and can be achieved with a blend of two eo~ponents sold by the Du Pont 9 . 2 ~

Company under Trade name~ Surlyn~ and nynel~; the ~roportions o~ components in the blend depend on the properties sought after.
In order to provide adhesion, one of the s~lrfaces to be jointed is ~oated with an appropriat:e(~ blend of Surlyn~ an~
Bynel~ and applied to the other surface; the assembly is thereafter heated. In the present invention, the heating step can advantageously be combined with the thermoforming of the embossed connecting element~. A fixture of this kind can replace the welding llne S ~f fig. 3. For removlng the two assembled surface elements, the adhesive force between them must be overcome. Afterwards, the two surface elements can be reclosed due to the male and female connecting elements which will mat;ch together.
As mentioned already in the foregoing disclosure, the present assembling device i5 usable to close pouches, bass and to ensllre the fastening of flexible ]ids over container of more or ~ess riyid texture; hence it is useful as fastenin~
means in all appliances where a releasable bond is necessary.

Claims

1. An assembling device for forming a releasable bond between two adjacent surface elements, comprising at least two connecting members, respectively one male and one female, placed in facing relation to each other for reciprocal engagement when said surface elements are assembled together, wherein at least one of the surface elements is prepared from a sheet or film material, a portion of which is embossed to provide at least said male connecting member, wherein said male connecting member has a closed periphery.

2. A device according to claim 1 wherein the female connecting member is also provided by an embossed portion of a sheet or film material.

3. A device according to claim 1 wherein each adjacent surface element comprises a plurality of connecting members.

4. A device according to claim 3 wherein the female connecting members comprise a surface element having holes extending through the thickness thereof.

5. A device according to claim 1 wherein the transverse cross section of the male and female connecting members have mating forms of substantially complementary size.

6. A device according to claim 1 wherein the external profile of the transverse cross-section of the male and female types of connecting member is circular for one type and polygonal for the other type, the size of such profiles being such that the reciprocal engagement of male and female connecting members develops frictional forces.

7. A device according to claim 1 wherein the embossed portion has a side face, at least a part of which is perpendicular to the surface of the surface element from which it is formed.

8. A device according to claim 2 wherein the embossed portion has a side face, at least a part of which is perpendicular to the surface of the surface element from which it is formed.

9. A device according to claim 1 wherein the cross-sectional size of said male connecting member is larger distal from the surface element than at the base.

10. A device according to claim 1 wherein the connecting members form an array of a plurality of parallel rows in each of said surface elements.

11. A device according to claim 10 wherein the connecting members of a row are in staggered configuration in repect to an adjacent row.

12. A device according to claim 1 wherein at least that surface element bearing at least a male connecting member is of thermoformable material.

13. A device according to claim 12 wherein the surface element of thermoformable material in at least the embossed part comprises a plurality of layers.

14. A device according to claim 12 wherein the surface element of thermoformable material in at least the embossed part comprises a plurality of layers of at least two different polymers.

15. A device according to claim 3 wherein at least the surface element provided with the male connecting members is in the form of a strip added to another surface.

16. A method for manufacturing the connecting members of the device according to claim 1, comprising the steps of heating at least one surface area of a thermoformable polymer sheet to its softening temperature;
placing the heated area in registration with a matrix in which a profile to be imparted to said surface is provided in negative replication;
applying the sheet against the matrix and subjecting it to reduced pressure from the matrix side, this reduced pressure being sufficient to cause the sheet material to be mated with the matrix profile;
cooling thereafter at least the embossed part of said sheet to below its thermoforming temperature; and removing the sheet from the matrix.

17. A method for manufacturing the connecting members of the device according to claim 1, comprising the steps of heating at least one surface area of a thermoformable polymer sheet to the softening temperature;
placing the heated area between a die matrix in which a profile to be imparted to said surface is provided in negative replication and a stamp having a raised profile corresponding to the negative profile of the die matrix;
driving the stamp into the die to deform the heated material;
cooling said sheet to below its thermoforming temperature;
removing the stamp from the die; and removing the embossed area of the sheet from the matrix.

18. The method of claim 17, further comprising subjecting the heated sheet, when between the die matrix and the stamp, to reduced pressure from the matrix side.

19. A method for manufacturing the connecting elements of a device according to claim 4, comprising punching holes through the thickness of said female connecting member.

20. A method for manufacturing the connecting members of a device according to claim 1 comprising cold forming the connecting elements from a deformable sheet material.