The present invention relates to a folding airtight container according to the preamble of claim 1 and a method for manufactoring the same.
Such a container is know from DE-A-2 412 447 in which a container is disclosed, which is currently know as a milk container. Such container comprises one flat sheet which is laminated to sealing materials before forming the box. Since a liquid will be filled in after the box is formed, ordinary corrugated paper material can not be used as a single material. Further no vertical rules are provided in the central portions of the left and right side walls and flaps are continuous with the side walls.
It has been difficult to enhance airtightness of a conventional folding airtight container of this type since materials per se of the airtight container are not heat-fusible and have a large thickness and are hardly fused by heat and pressed. Therefore, the inventor of the present application proposed an airtight container comprising a board and heat-fusible plastic films stuck to the board wherein inner and outer liners of the board are fused for serving as joiing margins while the cores, being the thick paper part provided at the peripheral side ends of the board (hereinafter referred to as cores) are eliminated.
However, the conventional folding airtight container has a problem that it takes much time and labour to eliminate the cores.
In view of the problem set forth above, the present invention has been made to solve the problem and to provide a folding airtight container and a method for manufacturing the same without eliminating the cores.
To achieve the above object, the folding airtight container according to the present invention is characterized by the features of the present independent claims.
With the arrangement of the folding airtight container, it is possible to form thin sealing pieces without eliminating the cores of the board and possible to seal each of the sealing pieces by heat-fusing or adhesive agent with assurance and without possible leakage of the contents of the container.
According to the method for manufacturing the folding airtight container, it is possible to manufacture the folding airtight container set forth above with simplicity.
The above and other objects, features and advantages of the present invention will become more apparent from embodiment four of the following description taken in conjunction with figures 10 to 12 of the accompanying drawings. Other embodiments without the bag-shaped flat sheet (3) are not claimed.
A folding airtight container according to a first embodiment of the present invention will be described with reference to Figs. 1 to 3.
A folding airtight container V comprises a board 1 having substantially rectangular shape and formed in a box-shape, a rectangular flat sheet 3 stuck to the inside surface of the box-shaped board 1 (the sticking portion are denoted at one dotted line in Fig. 1), wherein the flat sheet 3 is protruded from the board 1 at the top and bottom ends and one side end thereof and the protruded portions forming sealing pieces 5, 7 and 7. There is protruded a joining margin 8 forming a sealing piece 5a at another side end of the board 1 to which the flat sheet 3 is not stuck. The sealing piece 5a can be peeled off. The board 1 has scoring lines to be folded, described later, but has no cutting lines or perforations. The board 1 has wide front and rear surface walls 13 and 13 at the middle portion thereof and narrow left and right side walls 15 and 15 respectiely defined by upper and lower scoring lines 9 and 9 and four vertical scoring lines 11 wherein flaps 17 and 19 are provided at upper and lower portions of the walls 13 and 15 and continued laterally to each other.
Inasmuch as it is impossible to fold the flaps 17 and 19 when they are continued laterally and integrated with each other, there are formed isosceles triangles having both sides 21 and bases 9a for demarcating the side walls 15. A kraft paper is used as the flat sheet 3 to which a heat-fusible polyethylene film is laminated.
In assembling the folding airtight container, the sealing pieces 5 and 5a provided at both the left and right ends thereof are joined and subjected to heat-fusing, thereafter the resulant heat-fused sealing pieces 5 and 5a are stuck to the front surface wall 13 and the joining margin 8 is stuck thereto (Fig. 3). The folding airtight container assembled in such a square tubular shape is folded flatly and supplied to users. The users fuse the sealing pieces 7 and 7 confronted at the lower portion of the board 1 by heat and fold the flaps 19 for forming triangular welts 19a while the flaps 17 are closed and the triangular welts 19a are sticked to the side walls 15. The folding airtight container forms a cover at the upper portion thereof after filling the material therein in the same manner as forming the triangular welts 19a. The triangular welts 19a can, as shown in two-dotted lines, be stuck to the flaps 17. In any case, a sticking piece 7a provided at one of the sealing pieces 7 and 7 is folded down.
In manufacturing the folding airtight container, the board 1 is manufactured by a corrugating machine which board 1 is formed in a box-shape and the flat sheet 3 having an inner surface made of paper and an outer surface made of heat-fusible plastic film is stuck to the board 1 at the inner side surface thereof. The flat sheet 3 may be made of heat-fusible plastic films at both surfaces thereof.
A folding airtight container according to a second embodiment will be described with reference to Figs. 4 to 6. Elements same as those in the first embodiment have same numerals and explanation thereof is omitted.
In forming a cover of the airtight container, the flaps 19 of the left and right side walls 15 are positioned under the flaps 17 of the front and rear walls 13 so that the flaps 19 can form the isosceles triangles and connection pieces 23 and 23 for connecting the flaps 19 with the flaps 17 are formed at the lower ends of the flaps 19 and the flaps 17 so that the flaps 19 and 17 are interlocked with each other when they are folded. One of the flaps 17 has a non-sticking portion 22 at the tip end thereof to which the flat sheet 3 is not stuck. There is defined a sticking piece 7a in one of the sealing pieces 7 and 7 which piece 7a can be inserted into the gap between the non-sticking portion 22 and the flat sheet 3 so that a tape 24 is liable to stick to the upper portion of the non-sticking portion 22 different from the case where the sticking piece 7a is exposed.
Cutting slits 26 are formed between the flaps 17 and 18 same as type A of the manufacturing method of the corrugated cardboards according to Japanese Industrial Standards. The flaps 17 and 19 can be peeled off from the flat sheet 3 without impeding the formation of the lower cover by the flat sheet 3 while only the flaps 19 can stick to the flat sheet 3 at the isosceles triangular bandage 19a formed by the flaps 19 which isosceles triangular welt 19a having the bases thereof by demarcating line 9a demarcating the side walls 15.
There are provided vertical scoring lines 25 and 25 in both the central portions of the side walls 14 and the flaps 19 so that they can be folded flat from the tubular shapes. When the folding airtight container is supplied to the users, since the folding airtight container is folded while the both ends sealing pieces 5 and 5 and the lower end sealing pieces 7 and 7 are stuck to each other (in this case, the lower end sealing pieces 7 can be previously stuck to each other and are foldable inside and outside thereof).
A folding airtight container according to a third embodiment will be described with reference to Figs. 7 to 9. Elements similar to those in the first and second embodiments have same numerals and explanation thereof is omitted.
The arrangements of the board 1 and the flat sheet 3 are substantially the same as those of the first embodiment excepting that there are provided vertical scoring lines 25 for folding purpose. The relation between the flat sheet 3 and the flaps 19 of the left and right side walls 15 and the flaps 17 of the front and rear walls 13 are as follows. The flaps 17 can be peeled off from the flat sheet 3 so that the flaps 19 are folded under the flaps 17 and the flaps 19 are stuck to the flat sheet 3 at the isosceles triangular welt 19a formed by the flaps 19 which isosceles triangular welt 19a having the bases thereof by demarcating line 9a demarcating the side walls 15.
A folding airtight container according to the fourth embodiment which defines the invention will be described with reference to Figs. 10 to 12. Elements same as those in the first to third embodiments have same numerals and explanation thereof is omitted.
An arrangement of the folding airtight container of the claimed fourth embodiment is substantially the same as that of the folding airtight container of the second embodiment excepting that the flat sheet 3 is formed in a bag shape and stuck partially to the board 1. With such an arrangement, the board 1 can be reused by peeling off the used flat sheet 3 and substituted by new flat sheet 3.
The board set forth in the first to fourth embodiments of the present invention is typically represented by a corrugated cardboard including a plastic Corrugated board but it may include a thick paper, a cardboard, a resin sheet, a resin plate, a resin board, a plywood and a fiber board and the like.
Although the invention has been described in its preferred form with a certain degree of particularity, it is to be understood that many variations and changes are possible in the invention without departing from the scope of the claims.