FI89023B - Method for the manufacture of laminate material - Google Patents

Description

1 39023

A method of making a laminate material

The invention relates to a method of manufacturing a laminate material, which material has the features set out in the preamble of claim 5.

These laminate materials are generally used as a packaging material, with an intermediate layer of heat-sealable plastic between the two outermost layers 10 on the opposite side of the plane of the material, which acts as a layer connecting the outer layers, and at the same time e.g. moisture protection. The outermost layers can be, for example, layers of fibers, such as paper or cardboard.

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The laminate materials described above are used, for example, to package rolled products, such as paper rolls produced by large paper mills. With the current lamination technique, it has proved difficult to obtain a wide, i.e. n.

more than three meters of laminate material, which could be used to pack e.g. wide rolls of paper, the production of which: has become widespread.

25 A method is known from Finnish patent 73264. ***. to join the two laminated webs in parallel, wherein the edge web of the second web facing the edge zone of the second web has the bare layer material exposed, and this is heat sealed to the edge band of the second web consisting of the material of the second outermost layer.

It is an object of the invention to provide a method for producing a laminate material in which the joint can be improved and e.g. In order to achieve this, according to the invention. *: the method is mainly characterized by what is set forth in the characterizing part of claim 1.

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The invention is based on the idea that the laminate material is formed by joining together at its longitudinal edges at least two elongate 5 laminate webs with corresponding layers.

The joint is made in such a way that the adjacent longitudinal edge zones of each laminate web are formed thinner than the center of the web so that in each web the second surface layer is not extended to the longitudinal edge and the webs are placed side by side so that said thinner main webs are together by means of a heat-sealable interlayer material forming the surfaces of both of the above-mentioned edge zones.

Other preferred embodiments of the invention are set out in the appended subclaims. Thus, for example, there are several ways of arranging the transverse profiles of the edge zones of the laminate webs 20 so that the joint also becomes flat in the finished laminate.

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The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 shows the edge areas of laminate webs to be joined by the method according to the invention in the form of a transverse section 30 before facing them, · • · · • · ♦ · ♦: Fig. 2 shows a finished laminate material made by the method according to the invention, and • * • · · ♦ 35 * * Fig. 3 schematically shows an apparatus suitable for the manufacture of a laminate material • · *. ** from above.

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Figure 1 shows the two laminate webs to be joined side by side in a section perpendicular to their longitudinal direction and their plane, the thicknesses of the material-5 layers being exaggerated to increase clarity.

Each track 4 has the outermost surface layers 1, 3 on opposite sides of the track plane and an intermediate layer 2 of plastic connecting them. The surface layers 1 and 3 are characterized in that they remain unchanged at the softening temperature of the material of the intermediate layer 2. Each track 4 has a standard plate edge zone 4a bounded on one side 15 by the outermost edge of the entire track 4 and on the other side in the direction of the center of the track by the outermost edge of the second surface layer 3. The edge zones 4a therefore have a thickness less than the central part of the track 4, since the above-mentioned surface layer 3 does not extend to the outer edge of the track 20.

As can be seen from Figure 1, the material of the intermediate layer 2 • ·:: forms the outer surface of the edge zone 4a between said outer edge of the surface layer 3 and the outer edge 2 5 of the entire track 4. The picture also shows how to layer 3 • ·. · * ·. the layer 1 on the opposite side forms the outer edge of the whole track 4 in both tracks, and the outer edge of the intermediate layer 2 does not extend all the way to this edge, but remains at this point in Figure 1 by reference numeral 30 5 marked area where the surface of the edge zone 4a • · · * · consists of the above-mentioned layer 1 material.

• · · • · · • «· ^ As shown in Figure 1, two adjacent tracks 4. ···. are run opposite each other so that their edge zones, • · * · * 35, which are equally wide in each track 4, * * overlap and face each other so that the surfaces • «visible next to the surface layer 3 not extending to the outer edge of the track meet.

4 89023 In this case, the intermediate layers 2 exposed in the edge zone 4a come into contact, and by applying the softening energy of the plastic material of the layer 2 to the joint, the zones 4a can be sealed together. As the plastic material 5, a heat-sealable plastic material can be used, preferably a polyolefin such as polyethylene or polypropylene.

The edge zones 4a can be aligned so that they 10 overlap for the most part. In this case, the edge of the Layer 1 forming the outer edge of the second track always comes next to the edge of the layer 3 of the second track. The alignment can be performed with such accuracy that only a very narrow seam remains on both sides of the finished laminate. Figure 1 shows how the area 5 between the outer edge of the web 4 and the outer edge of the layer 2 forms a space 5 at the moment of joining where molten layer 2 material can spread laterally to compensate for the total thickness of the layers in the edge zone 4a greater than the standard thickness of the layer 2. midbody. It is also possible to arrange the thickness of the layers 2 in the edge zone 4a such that in at least one of the opposing edge zones this thickness 25 is smaller than the above-mentioned constant thickness in the middle part of the track.

• ». · **. It is also possible that the total thickness of the materials of the intermediate layers is substantially equal to the above-mentioned constant thickness. This alternative is illustrated by the dashed lines in Figure 1, and if the dimensions 30 are performed correctly, the layer 2 material * · '· can extend to the entire outer edge of the track 4, and • · · * · *' lateral expansion spaces 5 are then not required.

. ·· '. In Figure 1, the dashed lines show the case where • · • · ♦ • # 35 in both opposing edge zones 4a this thickness of the material of the intermediate layer 2 is approx. *: less than half of the above standard thickness in the middle of the track.

Em. the thickness can be arranged in the edge zone 4a 5 89023 also to decrease evenly towards the outer edge. When talking about the thickness of the intermediate layer 2 in the edge region, it is meant in this context its average thickness.

The thicknesses of the intermediate layers 2 in the edge region can be adjusted in the lamination technique by general control methods, e.g. by adjusting the gap of the extruder feeding the material of the intermediate layer 2.

Figure 2 shows a finished laminate material formed of two webs 4. In order to obtain a uniform material over the entire width, the laminate webs 4 to be joined must be of the same thickness and likewise the adjacent layers 1 and 15 3 must be of the same thickness in the adjacent webs.

It is most practical to form a laminate material from individual webs whose structure is symmetrical with respect to a central plane dividing the web 4 into two equal thicknesses, whereby the joint can be made of a similar laminate material by turning the second laminate material in the opposite direction and guiding the joint surfaces 4a.

• · «· ·: ***: Figure 3 shows a practical solution by which 25 two or more laminate webs 4 can be run • ·. · **. at one of their marginal zones 4a. The individual • · · tracks 4 can be, for example, on rollers with rollers 6, of which • · · ^. they are driven in a different plane towards each other at the junction marked A in Figure 6, where the melting energy of the intermediate layer 2 • · • · · * · material, such as infrared or * · · * .1 1 microwave radiation, is applied to the region of zone 4a. Energy can also be introduced by means of a heating roller or flame heating (so-called flame heating method). The methods used depend, of course, on their suitability for the process, e.g.

1 line speed. Zones 4a can be guided to the junction • · ·. ** with suitable guide roller arrangements.

Immediately after the joint A there is a pair of press rollers 7 39023 which finally press the zones 4a together and at the same time guide the full-width laminate material onto the storage roll 8. This provides a wide path of narrower tracks which can be easily made by conventional lending technique. E.g.

for the packaging of large rolls of paper, it is possible to make a web more than 3 m wide.

It should be noted that although Figure 3 shows the use of two webs 4 for the production of a wider laminate material, the material can also be produced from more than two separate webs 4, which may be eism. constant width. In this case, both longitudinal edges 1 of the middle tracks 4 must have 15 edge zones 4a as shown in Fig. 1.

The width of the edge zones depends on the basis weight of the material, and must then be such that the finished material has sufficient lateral tensile strength at the joint.

The outer edges of the finished laminate material may be flat, i.e. all layers 1, 2 and 3 terminate f 1: the outermost edge of the material. However, the outer edge of the finished laminate material may also be as shown in Figure 1 at this point, i.e. one of the layers 1 and 3 does not extend to the outer edge, so that it can be used for packaging paper rolls as described in the applicant's previous patent application 873850.

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Claims (3)

A process for producing flexible, rollable laminate material in which there is provided an intermediate layer (2) of plastic and on opposite sides thereof laminated surface layers (1, 3) which remain unchanged at the softening temperature of the material of the intermediate layer (2), the laminate material is formed by joining at its longitudinal edges (4a) two or more elongate, the corresponding layers containing laminate webs (4), whereby for transposing said jointing, beds adjacent to each other (4) have an edge zone (4a) of a certain width lower thickness at the center portion of the web 15 because one of the surface layers (3) does not extend to the outer edge of the web, the joining being such that the surfaces of the edge zones (4a) which are visible adjacent to the surface layers (3) is opposed and heat bonded together by the material of the intermediate layer (2), which forms the surface of at least one of the edge zones, wherein the adjacent edge zones (4a) the sum thickness of the material of the intermediate layer (2) is substantially equal to that of the intermediate layer (2), ··, constant thickness of the middle portion of the web, characterized by the fact that the surface of the bed adjacent to each other is the edge zones (4a). ) consists of the material of the intermediate layer (2). »· ·» »• · * i 2. A method according to claim 1, characterized in that the zones (4a) of the intermediate layer (2) are the thickness of the intermediate layer (2) of the bed adjacent to each other. is about half the thickness of the intermediate layer (2); the middle part of the web (4). • · * 3. A method according to claim 1, characterized in that the edge zones (4a) of the beds adjacent to each other are the thickness of the intermediate layer (2) *: **: material reduces to the outermost edge of the bed. banana. • · • «