A SHEET PIECE CONSISTING OF AT LEAST THREE MATERIAL LAYERS OF PAPER

Abstract: A sheet piece intended to form, for example, an encasing wall (53) of a portable container, consisting of a plurality of material layers (54, 55, 56) mainly of paper. The material layers are provided with a large number of localized impres­ sions distributed uniformly over the surface of the layers with spaces in between the impressions. The impressions extend from the principle plane (58, 59, 60) of each layer. The impressions (57, 62) in adjacent layers are, with respect to their posi­ tions, displaced relative to one another as viewed in the nor­ mal direction of their principle planes (58, 59, 60). This involves that the impressions in one layer are located directly in front of the spaces in adjacent layers. Each of the layers is joined with its adjacent layers by means of an adhesive, whereby a large number of closed cells (64) are created, so that at most two layers are directly joined together with each other.

Description: The present invention relates to a sheet piece consisting of at least three material layers of paper forming, for example, an encasing wall of a portable container. An insulating sheet made up of at least two layers of a plastic material which are heat sealed is known from DE-A-2 035 449. At least one of the plastic layers is provided with a large number of uniformly distributed localized impressions which, together with the remaining layers, form closed cells. The purpose of the present invention is to provide a sheet piece, forming a stable heat and cold isolating wall by utilizing low cost paper sheets. Said purpose is achieved by means of a sheet piece intended to form, for example, an encasing wall of a portable container, consisting of at least three material layers of paper, each of which extends in a principle plane and is provided with a large number of localized impressions with spaces therebetween distributed uniformly over the surface of the layer, said impressions extending from the principle plane of every layer in the same direction normal to said principle planes, the layers being placed relative to each other in such a manner that, in the direction normal to said principle planes, the impressions in one layer are located directly in front of the spaces in adjacent layers and each of the layers is joined with its adjacent layer or layers by means of an adhesive, whereby a large number of closed cells are created, so that at most two layers are directly joined together with each other. The invention will be described more precisely hereinbelow by means of an example, with reference to the accompanying drawings in which fig. 1 shows an example of a portable container built up by means of sheet pieces according to the present invention; fig. 2 illustrates a continuous material web of sheet pieces according to the present invention forming partially completed containers; figs. 3 and 4 show a partially broken perspective view of an upper section of the container in its open and its closed configuration, respectively; fig. 5 illustrates a broken view, in enlarged scale, of a portion of a sheet piece forming encasing walls of the container, and fig. 6 shows schematically a cross sectional view in even greater scale taken along the line VI-VI in fig. 5. A completed container 1, built up by means of sheet pieces according to the present invention, is illustrated in fig. 1 and, by way of introduction, its principle design will be described. The container 1 consists mainly of a handle member 2 and an encasing member 3, which is intended to contain the object or objects, which are to be carried using the container. The encasing member 3 consists mainly of two oppositely positioned encasing walls which consist of said sheet pieces and are joined along the side edge sections 4 and 5 of the container and the bottom edge section 6. The walls are made of a paper material which gives the container a certain stability while at the same time making the container shapeable so that a space is created between the two walls into which the object in question may be placed. In the simplest case it is conceivable that the handle member 2 consists of a single handle, fastened at the edge of the opening section 7 of one of the two walls. The container has an opening which is delimited by the opening edge section 7 of the two walls. For the case in which only a single handle is provided, the opening may be closed by applying to the edge of the opening section of each of the walls an adhesive substance, so that the edges of the opening sections of the respective walls, when pressed together, adhere to one another. An example of the attachment of the handle member and also a method and a machine for such an attachment is shown in the application No 86850329.3 from which the present application is divided. Fig. 2 shows container material in the form of a continuous material web 22 consisting of one or several layers of paper extending over the full width of the web with paper strips 30, attached by means of adhesive, along both edge sections 41 of the material web and strings 28 applied in the form of loops between the material web and the strips 30. In this arrangement the handle loops are formed with a desired relative separation whereby the string is allowed to run through the bottom of the container to which it will thereby provide a certain degree of reinforcement. Also a certain degree of reinforcement is provided by the paper strip 30 in the bottom of the containers. In a following operation, a separate device will join the material web 22 along with the handle members and strip 30 to the material web which is to form the container's opposite wall and which has been provided with glue in accordance with some predetermined pattern so that the material webs may be glued together along the side edge sections 3 and 4 and the bottom edge section 6 whereupon separate containers will be obtained by means of cutting along the lines 46. At this point the strings will also be cut at their points of intersection with the lines 46. Two sections 48 of the handle member 2 are consequently affixed between one of the layers of material 22 and the strip 30. Each of these sections consists of a first portion 50 and a second portion 51, positioned at an angle to the first portion. Figs. 3 and 4 show clearly how the upper section of the container is constructed and how it may be closed. In the given example the container is provided with a single handle member 2 which is secured to the opening edge section 7 of one of the encasing walls. Fig. 3 shows how the container appears when it contains some object which is to be carried, whereby the flexible encasing walls are bent away from each other between the side edge sections 4 and 5 so that an opening 52 is created, through which the intended contents of the container can be inserted. The encasing wall which does not have a handle member at the top is arranged with an edge 47 folded down, which is provided with a fastening surface which consequently faces outwards from the folded down edge. When closing the container the folded down edge 47 is folded up and its fastening surface is pressed against the inside of the opposite opening edge section 7 which is provided with a surface made self-adhesive by means of a suitably chosen glue, so that the container assumes the general appearance shown in fig. 4, after that an object to be carried has been inserted into the space, enclosed by means of the encasing walls 53. In addition to closing the opening 52 the handle member 2 will hereby be anchored to both of the encasing walls opening edge sections 7 by means of the joining of the two said opening edge sections so that a uniform tension load arises in the container when it is lifted by means of the handle member 2. The fastening surface of the folded down edge 47 may also be provided with a self-adhesive material. In accordance with the present invention the container is made heat insulating by means of fashioning each of the encasing walls 53 out of at least three material layers, generally of paper, which are so embossed that they together form an encasing wall, the thickness of which is considerably greater than the sum of the thicknesses of each of the material layers (see figs. 5 and 6). It is advantageous to form the one material layer 54, which comprises an outer material layer of the encasing wall, of a paper which has a thickness considerably greater than the other material layers 55 and 56. It may be pointed out that one may for example obtain a wall thickness of 2.5 mm with an outer layer 54 made of wet strong kraft paper with, for example, an area weight of 35 g/m², while the other material layers 55 and 56 may be produced from relatively thin waste paper with an area weight of, e.g., 17 g/m². All of the material layers are deformed in a similar manner, suitably by means of embossment, so that a great number of impressions 56 are obtained, extending from the original plane of each of the material layers, such a plane being designated by 58 for the outer layer 54, by 59 for the middle layer 55 and by 60 for the inner layer 56. The broken portion of the encasing wall 53, shown in fig. 5, may be considered to be viewed from the outer layer 54, so that the impressions 57 consist of areas raised above the main plane 58. These raised areas 57, as well as the impressions in the other layers, are distributed uniformly over the entire surface of the encasing walls 53 with predetermined separation, so that spaces are created between the impressions 57, which generally correspond to or somewhat exceed the dimension of the impressions 57. These may assume a variety of different shapes and in the given example the bottom surface 61 of the impressions are shown as being square, however even polygonal or circular shapes are conceivable. As may be seen, the impressions 57 are arranged so as to form rows extending diagonally which, in the given example, implies a direction of 45° relative to the vertical or longitudinal axis of the container, so that the corners of the impressed surfaces are oriented in the direction of said axes. Both of the other material layers, i.e., the middle layer 55 and the inner layer 56, are also provided with impressions, suitably aligned in the same direction as the impressions in the outer layer. In such case the impressions of the inner layer are located coincidentally with those of the outer layer when viewed from the side of the encasing walls, i.e., according to fig. 5, whereas the impressions of the middle layer 55 are displaced in the direction formed by the diagonals of the squares by a distance corresponding to half the separation between the impressions so that the impressions of the middle layer fall between the impressions of the outer layer. In fig. 5 this is shown by the four impressions 62 illustrated as dotted lines. For the sake of clarity only, the remaining impressions in the middle layer have been deleted, however they are equal in number to the impressions in each of the inner and outer layers. All of the layers in each encasing wall are joined together by means of a suitably chosen glue, which is applied to the mutually facing surfaces of the material layers. It is sufficient to apply the glue, e.g., to the outer layer 54 and the inner layer 56 and for practial reasons it is suitable to do so over their entire surfaces, whereby the layers are laid together in the form of whole material webs before the container is completed in accordance with the description above. In this manner closed cells 64 are formed, which in the present example have a hexagonal cross sectional shape as is shown in fig. 6. The cells may for example be such as to form an angle 63 of 70° to the respective principle planes 58, 59 and 60 of the material layers. In the given example one side 57 of the impressions is approximately 1 mm in length or slightly longer. It is advantageous that the depth of the impressions be of corresponding size. The angle 63 should be as large as possible but it is limited primarily by the deformation characteristics of the material layers. By means of the construction of the material layers described above a highly efficient heat insulating container is achieved with encasing walls which enclose closed air cells. Furthermore, a stiffness is achieved which, in relation to the thickness of the material layers, is well suited to allow the necessary flexibility in order that the container may adapt to the size and shape of the contained objects while displaying sufficient stiffness to give good protection to the contents. It is possible to displace the impressions in the middle layer 55 in a direction transverse the direction of said rows rather than diagonally, but this does not yield the same insulating ability since long, narrow surfaces thereby arise along which all three material layers are joined together. In the given example a large number of joining surfaces between the material layers is attained, which are local and where the material layers are joined with each other only in twos. In certain cases it may be desirable to choose a larger number of material layers in order to yield improved insulating ability and firmness of the container and in such cases material layers are added in the same manner, so that every other layer is displaced diagonally relative to the longitudinal direction of the impressed rows. The invention is not limited to the example shown above but rather can be varied within the framework of the following claims. A package with two handle members can for example be produced, i.e., with a handle member affixed to the opening edge sections of each of the two walls by means of a strip along each opening edge section. Said strip 30 may also extend over the entire length of the container and, having the same width as the material web 22, thereby form one of the material layers of the container. The container of the example shown is well suited for, e.g., garden products, such as flowers, plants or potted plants but it can also be given a completely different shape and be used for completely different purposes.

Claims: A sheet piece intended to form, for example, an encasing wall (53) of a portable container, consisting of at least three material layers (54, 55, 56) mainly of paper, each of which extends in a principle plane (58, 59 , 60) and is provided with a large number of localized impressions (57, 62) with spaces therebetween distributed uniformly over the surface of the layer, said impressions extending from the principle plane (58, 59, 60) of every layer in the same direction normal to said principle plane, the layers being placed relative to each other in such a manner that, in the direction normal to said principle plane, the impressions in one layer are located directly in front of the spaces in adjacent layers and each of the layers is joined with its adjacent layer or layers by means of an adhesive, whereby a large number of closed cells (64) are created, so that at most two layers are directly joined together with each other. A sheet piece according to claim 1 and forming together an encasing wall (53) encasing a space in which objects can be enclosed, characterized in that said impressions (57, 62) are in rows extending in a first direction and also in a second, transverse direction, wherein the impressions in adjacent layers are displaced relative to one another as viewed in a direction normal to said principle plane by a distance which is greater than the separation between the impressions, said displacement being accomplished in said first direction as well as in said second direction. A sheet piece according to claim 1 or 2, characterized in that the material layer (54) for forming an outer material layer of the encasing wall is thicker than the other material layers (55, 56).

Inventors: PATRIKSSON, STIG
Applicants: I.H. PAPER AB
Application year: 1986
Main classification: B65D65
IPC codes: B65D30