US 3734395 A
A bag has side walls and a flat bottom having lateral folds and corner folds. An insert of thermally insulating material is located in the flat bottom extending underneath the corner folds and having folded lateral portions which extend beyond the lateral folds but not beneath the corner folds. The folded portions of the bottom are bonded, adhesively or by heat-bonding if the bottom is of requisite heat-bondable material.
Description (OCR text may contain errors)
llnited States Patent 1191' Erk et al. 1 May 22, 1973 BAG  References Cited  Inventors: Amir Erk, Grossdornberg; Ottomar UNITED STATES PATENTS Tiessmaun; Klaus Schirrich, both of 2,359,190 9/1944 Avery etal. ..229/5s Bl all of Germany 2,420,212 5 1947 Volksdorf 1 ..229/5s x 2,853,225 9/1958 Bauer ..229/58  Assgnee- Kmk Belefeld' 3,514,033 5 1970 Goodwin ..229/58 x Germany  Filed; M 26, 1971 Primary Examiner-Davis T. Moorhead Attorney-Michael S. Striker  Appl. No.: 145,085
 ABSTRACT Foreign Application Primity Data A bag has side walls and a flat bottom having lateral May 29 1970 Germany "P 20 26 3303 folds and corner folds. An insert of thermally insulating material is, located in the flat bottom extending underneath the corner folds and havin folded lateral 52 U.S. Cl ..229 58 3 E Int Cl B65d 33100 portions which extend beyond the lateral folds but not  Fieid 229/58 55 beneath the corner folds. The folded portions of the bottom are bonded, adhesively or by heat-bonding if the bottom is of requisite heat-bendable material.
10 Claims, 5 Drawing Figures Patented May 22, 1973 Fig.
/n vem0r A, n K mronn Texsrnvu BAG BACKGROUND OF THE INVENTION The present invention relates generally to bags, and more particularly to flat-bottom bags.
Flat-bottom bags, also known as cross-bottom or block-bottom bags, are known which consist at least in part of heat-bondable material so that, when the necessary folds are carried out, the bag is closed at the bottom by sealing it under the influence of heat. The difficulty with the existing prior art is that when sealing is carried out, those portions of the side wall which overlie the bottom interiorly of the bag in contact therewith-while the bag is in the folded condition in which the sealing takes place rather than in unfolded condition in which no portions of the side wall would be in contact with the bottom-frequently are also sealed to the bottom. Such a bag of course must be discarded because it is not'usable.
It is already known in cross-bottom or block-bottom bags composed of several layers or plies of paper, to in corporate into the bottom a reinforcing strip which extends under the corner folds and beyond the lateral fold lines of the bottom. The rectangular reinforcing strip has the dual function of serving for reinforcing purposes and also to seal the bottom in such a manner that subsequently introduced contents cannot enter between the individual paper layers of the bottom of the bag.
SUMMARY OF THE INVENTION It is a general object of the present invention to promeans is composed at least in part of heat-bonded material and comprises lateral folds and corner folds. An insert of thermally insulating material is accommodated in the flat bottom means extending underneath the corner folds and having folded lateral portions which extend beyond the lateral folds but not underneath the corner folds.
This insert prevents excessive transfer of thermal energy in the region of the bonding linesthat is heatsealing lines-where the folded-together portions of the bottom are adhered in order to close the bottom, that is the lower end of the bag. These heat-sealing lines on the one hand connect the corner folds with the lateral folds, and on the other hand connect the lateral folds with one another. By the provision of the insert any adhering during such sealing operations of the bottom to portions of the side wall which are in contact with the bottom is avoided.
Furthermore, the provision of the lateral portions on the insert which extend under the lateral folds but not under the corner folds, means that the insert is provided with recesses in the region of its corners and, because of this, the lateral folds of the bottom can be welded or bonded with the corner folds over the entire width of the bottom without interference by the insert. The foldable portions of the insert provide the advantage that they reduce the necessity for a precise positioning of the insert with reference to the bottom before the latter is folded and bonded, so that the manufacture of the bag is greatly simplified.
In so far as the material for the insert is concerned, I have found that stiff paper or cardboard is entirely adequate for providing the desired retardation of thermalenergy transfer. Of course, the insert at the same time constitutes a reinforcement for the bottom which is highly desirable, particularly in cases where the bag including the bottom is of synthetic plastic material which is often strongly stressed in use.
The insert can be adhesively or otherwise secured with those portions of the corner folds underneath which it extends; on the other hand, if it is provided on one side with a layer of heat-bondable material, such as a suitable synthetic plastic, the securing need not be adhesive but can instead be by heat bonding, and in this case the connection can be established at the same time as the other portions of the bottom are heat-bonded to one another.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a somewhat diagrammatic view illustrating the lower end including the bottom of a bag according to the present invention, with the bottom partially folded;
FIG. 2 is the same view as FIG. 1 but illustrating the insulating material insert in place in the bottom of the bag;
FIG. 3 illustrates the embodiment of FIG. 2 with the bottom in finally folded and bonded condition;
FIG. 4 is a diagrammatic section on line IV-IV of FIG. 2; and
FIG. 5 is a diagrammatic section on line V--V of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail it will be seen that reference numeral 1 identifies in toto a tubular component which is provided with the broken-line illustrated side wall gussets, so that it can be folded flat as illustrated. It is provided with the customary block bottom which is shown in partially folded condition in FIG. 1. Side folds 2 and 3 are illustrated, as well as the corner folds 4 and 5. FIG. 2 shows how an insulating material (thermally insulating) insert 6 is placed into the partially folded bottom, through the openings 7 and 8. FIGS. 2 and 3 show clearly that the insert 6 has such a width that it extends at opposite sides underneath the corner folds 4 and 5. It is further provided, in the illustrated embodiment, with adhesive strips 9 and 10 by means of which it is adhesively connected with the overlying portions of the corner folds 4 and 5.
In addition, the insert 6 is provided with lateral projections or portions 6a which extend beyond the fold lines 11 and 12 of the lateral folds 2 and 3 and which can thus be folded together with the latter. The portions 6a are recessed at the corners so that they do not extend beneath the corner folds 4 and 5. FIGS. 2 and 3 show clearly that these corner recesses 6b of the insert 6 assure a bonding of the lateral folds 2 and 3 with the corner folds 4 and 5 over the entire width of the bottom.
Once the insert 6 has been positioned as illustrated in FIG. 2, the bottom is folded to the position illustrated in FIG. 3, and thereupon the lateral folds 2 and 3 are connected with the corner folds 4 and 5 along bonding lines 13 and 14, as by heat bonding if the material is of requisite type, and the lateral folds 2 and 3 are connected with one another by a bonding line 15. In FIG. 3 the bonding lines 13 and 14 are above the adhesive strips 9 and 10.
It is pointed out, however, that the adhesive strips 9 and could be omitted, and that instead the insert 6 could be provided with a layer of heat-bendable material (thermoplastic material), for instance of the same type as the-bag itself, in which case they can then be heat-bonded with the overlying portions of the corner folds, 4 and S at the same time as the bonding steps discussed above with respect to FIG. 3 are carried out. The sections of FIGS. 4 and 5 show details of FIGS. 2 and 3, respectively. I
It is also pointed out that instead of the separate insert 6, for instance of stiff paper or cardboard, the bag can be provided at least in the region of the subsequently provided bonded lines or bonding seams with a layer or coating of an insulating material, for instance pigment paint, lacquer or the like which provides the desired thermally insulating function.
It will be understood that each of the elements described above, or two or more together, may also find auseful application in other types of applications differing from the types described above.
While the invention has been illustrated and described as embodied in a bag, it is not intended to be limited to the details shown, since various modifications and structural changes can be made without departing in any way from the spirit of the present inventron.
7 Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:
1. A bag, comprising side wall means; flat bottom means at the lower end of said side wall means and comprised at least in part of heat-bondable material, said flat bottom means comprising lateral folds and corner folds; and thermally insulating means in said flat bottom means, extending underneath said corner folds and having lateral portions which extend beyond said lateral folds and have corners provided with recesses located underneath said corner folds so that no part of said lateral portions extends underneath said corner folds.
2. A bag as defined in claim 1, wherein said insulating means consists at least predominantly of relatively stiff paper.
3. A bag as defined in claim l,'wherein said insulating means consists at least predominantly of cardboard.
4. A bag as defined in claim 1, wherein said insulating means is an insert having two major sides, one of which is provided with a layer of heat-bondable material.
5. A bag as defined in claim 1, wherein said insulating means is an insert member bonded to said corner folds underneath which it extends.
6.. A bag as defined in claim 5, wherein said insert member is heat-bonded to said corner folds.
7. A bag as defined in claim 5, wherein said insert member is adhesively bonded to said corner folds.
8. A bag as defined in claim 1, said flat bottom means having a plurality of bonding seams and wherein said flat bottom means is provided with a coating of thermally insulating material in the region of said bonding seams and constituting said thermally insulating means.
9. A bag as defined in claim 8, wherein said insulating material is a thermally insulating lacquer.
10. A bag as defined in claim 8, wherein said insulating material is a pigment paint.