RU2258611C2 - Laminated packing material creasing method, packing material and package - Google Patents

Abstract

FIELD: equipment for making paper articles.

SUBSTANCE: package is produced of laminated packing material formed of cellulose pulp and having three-dimensional layer which gives a three-dimensional configuration to the package, and at least one side layer formed on one side of three-dimensional layer. Side and three-dimensional layers are directly or indirectly connected one to another over the full surfaces thereof facing each other. Method for package production by creasing and folding laminated packing material involves pressing creasing device in one side of laminated packing material to form crease lines and holding the packing material by supporting tool from opposite side thereof, wherein the supporting tool is substantially flat in area corresponding to area of creasing device application; folding the packing material about crease line. Above three-dimensional layer has latticed structure formed of cellulose fibers.

EFFECT: decreased thickness of obtained package, possibility to fold packing material through 180° in which total thickness of folded material is approximately equal to double unfolded material thickness.

7 cl, 8 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to a method for removing a packaging laminate made of cellulosic fibers and comprising a volume-giving layer, referred to herein as a bulk layer, consisting of a mesh structure of cellulose fibers and at least one side layer on at least one side of the volume layer, the side layer and the bulk layer is directly or indirectly connected to each other along substantially all of its facing surfaces.

BACKGROUND AND PROBLEMS

In the manufacture of packages, the material, usually a packaging laminate, is crushed using a creasing device forming a recess. The crushing device can be in the form of a thin ruler with a rounded smooth edge or in the form of a groove wheel with a rounded smooth edge that presses the material into a carefully made recess in the matrix. Due to this recess, the material is weakened along the so-called crease line. When crushing, the material leaves the plane of the laminate, forming a protrusion along the line of crushing, on one side of it, namely, on the side opposite to the one on which the recess is formed. Thus, the crease line acts as an indented fold, which is used to evenly fold the material at a given angle, usually 90 °, but there may be other bending angles, for example 180 °. For materials of different quality with different properties (corresponding to laminates of different quality and types), creasing rulers or other devices and matrices of various geometries are used to obtain the most pronounced indented fold. Typically, the thickness of the ruler or other crushing device, the width of the recess in the matrix, or the depth of collapse, i.e. depth of indentation of the crushing device.

According to the known folding method, the material is folded from the side on which the recess is made in it. In this case, a convexity is created from the inside of the corner formed during folding. Therefore, when folding, for example, 180 °, the thickness of the folded laminate will be greater than the double thickness of the laminate. In the case of smaller angles with this method of collapse and folding, bulges also appear along the line of collapse on the inner side of the corner.

The cause of the formation of a bulge during folding of a conventional laminate is a kink in compression that occurs on the side that is compressed during folding. The kink increases with bending, and the protrusion formed by the creasing ruler shrinks and turns into a bulge. Due to the accumulation of material at the folding line, the laminate tends to spring, restoring its original flat shape. This means that the folded edges are easily rounded, especially if they are under load, for example, when a box in the shape of a parallelepiped is squeezed in the hand or several packages are stacked on top of each other.

Thus, the disadvantages of the known method of crushing a conventional laminate are the displacement of the material from the plane and / or its movement to the folding line, which leads to the appearance of a bulge and an increase in the thickness of the folded laminate. Other disadvantages associated with this are that, due to deformations, the fold line will not be completely straight. In addition to the deterioration of the appearance of the package, this leads to the fact that packages that need to be stacked next to each other or on top of each other will have a different shape. Deformations in the folding line can cause tears in the protective or film layers, consisting, for example, of aluminum film, plastic film, varnish, etc. For example, if a film is applied on one side of the laminate and the fragility of the film material is greater than that of the cardboard of the laminate, then the bulge or other unevenness that occurs when folding can cause a crack in the film layer. Special types of cardboard that are printed or which require very good surface finishes can be coated with black paint, varnish, etc. Thus, a dent from the crease ruler can disrupt the surface coating, for example, creating cracks opening up the fibrous material below if folding is in the direction from the recess formed by the crease ruler.

A known method for solving the problem of bulge formation is described in SE 467302, where the protrusion formed by the crease ruler is removed mechanically. However, this method has several disadvantages, for example, a decrease in strength, the formation of dust, etc.

Another known method for reducing convexity (see SE 432918) uses auxiliary crushing lines to displace the material from the main crushing line.

In addition, it is well known that you can create several parallel lines of collapse and thus divide one corner into several adjacent corners. The disadvantage of this method is that the total thickness is too large. For example, when folded 180 °, the total thickness will be significantly greater than twice the thickness of the laminate.

SE 507095 describes one method for removing a bulge from a crease line in which there is no adhesion between the individual layers of the laminate, so they are deformed independently of each other.

In all the above examples of solving the problem associated with the displacement of material on the folding line as a result of deformation caused by crushing, the characteristic tendency is to remove or displace the material from the folding line or to avoid accumulation of material on this line.

EP 565013 solves a different kind of problem and describes a material consisting of several layers and having a core formed by compressed shredded paper. It is said that the material can be made with several grooves to give it flexibility, so that it can be used to wrap objects of various shapes. However, EP 565013 does not describe packaging obtained by folding, and wrinkling lines or a wrinkling method in the accepted sense of the word.

EP 484726 describes how, when folded, a foamy or loosened binder is compressed to reduce longitudinal stresses in an aluminum foil layer.

EP 546956 describes a material having a central layer of loosened cellulose fibers to improve the workability of the material.

From US 2770406, a packaging laminate is known comprising a porous bulk layer that contracts when folded. According to this document, the bulk layer is made of foam, in particular polystyrene with closed cells. Such material was considered very good in 1956, however, taking into account modern environmental requirements, requirements for reuse of materials, etc., it is currently completely unacceptable. In US 2770406 it is also said that cracks appear in corners of this type of cardboard material when forming a package in the outermost layer of kraft paper. Thus, according to this document, the problem associated with the formation of cracks is solved only for a laminate consisting of cellulosic fibers and plastic, and cannot be solved for a laminate consisting essentially of cellulosic fibers. In addition, nothing is said about how the crushing method is practiced.

FR 1341855 describes a corrugated cardboard laminate consisting of cellulosic fibers, but different from the laminate according to the present invention in that the bulk layer is not formed by a mesh structure of cellulosic fibers connected to the side layer of cellulosic fibers on substantially all of their facing surfaces . Figures 2a-b of this application relate to its prior art, which has inherent problems associated with kinks and deformations, i.e. the crushing method according to figa-b is presented as a method for which these problems are characteristic. FIGS. 3a-b illustrate a known crushing method, which, as stated in FR 1341855, is slightly better than the method of FIGS. 2a-b, however, instead, the solution shown in FIGS. 4a-c, which relate to the method of crushing, where in the extreme layer make slits or perforations.

DECISION AND ADVANTAGES

The invention is directed to solving these problems in a method of crushing packaging laminates made from cellulose fibers and containing a volume-giving layer, referred to herein as a volume layer, and at least one side layer on at least one side of the volume layer, the side layer and the volume layer directly or indirectly connected to each other essentially along all their facing each other surfaces.

The invention also relates to a packaging laminate having crushing lines made in this way, and to packaging made by folding such a laminate. Laminate is preferably used for packaging liquid and dry food products, as well as industrial and other products, or as an intermediate product for the manufacture of such material, or other end products.

According to the invention, a method for crushing packaging laminates according to claim 1 of the formula.

This method is carried out using a crushing device, which is pressed into the laminate from its first side, and a flat support tool is used on the opposite side of the laminate. The support tool may consist of the same stable flat support to obtain different types of crease lines. This greatly simplifies and reduces the cost of the method, both in terms of its implementation, and in relation to obtaining dents of different geometry only by changing the template in the crushing device. In the known method of crushing to change the geometry of the dent you need to change both the pattern of the crushing device, and the matrix.

According to one aspect of the invention, the side layer (s) are located on the first side of the laminate, the side layer being pressed into the bulk layer along the crease line, and on the side opposite to the pressed layer (s), the laminate is kept substantially flat .

According to the crushing method, the bulk layer is compacted in the region of the crushing line, which gives a great advantage. Compaction weakens the mesh structure formed in the bulk layer by single cellulose fibers. Due to the weakening of the mesh structure, it cannot withstand the compressive load from the lateral layer, when it is subjected to a compressive load during subsequent folding along the crushing line. As a result, the side layer deepens into the bulk layer. Thus, during subsequent folding, problems associated with the formation of bulges, delamination and possible formation of cracks in the lateral layers can be avoided, which is the case with the known crushing method. Such compression behavior of the bulk layer is particularly observed in the case of the most preferred laminate described in parallel patent application SE-AO-9802967-1.

According to another aspect of the invention, the bulk layer essentially or entirely consists of a sheet of paper or cardboard, which is formed separately from cellulosic fibers and then laid on the side layer (s) or formed directly on the side layer (s). In this case, wet or dry laying of bulk material can be used.

According to a further aspect of the invention, the bulk layer contains up to 40-95% cellulose fibers having a milling degree determined on a Canadian standard device of 550 to 950 ml, the density of the side layer (s) is higher than the density of the bulk layer, and the laminate has a bending stiffness coefficient calculated as the geometric mean for the longitudinal and transverse directions, more than 2.5 Nm ⁷ / kg ³ , but less than 14 Nm ⁷ / kg ³ .

According to another aspect of the invention, at least 60% of the bulk layer consists of fibers having a milling degree determined on a Canadian standard device of more than 600 ml, and the laminate has a bending stiffness coefficient of more than 3.0 Nm ⁷ / kg ³ , or, more preferably, at least 60% of the bulk layer consists of fibers having a milling degree determined on a Canadian standard device of more than 650 ml, most preferably at least 700 ml, but less than 850 ml, and the laminate has a bending coefficient of more than 4 , 0 Nm ⁷ / kg ³ . It is particularly preferred that the bending stiffness coefficient of the laminate is more than 5.0 Nm ⁷ / kg ³ .

It is desirable that the bulk layer has a density of 50-300 kg / m ³ , preferably 70-200 kg / m ³ , more preferably 100-180 kg / m ³ . The density of the side layer is preferably at least two times higher than the density of the bulk layer, preferably at least three times, most preferably at least four times. The density of the lateral layer may be 300-1500 kg / m ³ , preferably 400-850 kg / m ³ . It is advisable that the bulk weight of the bulk layer is 30-300 g / m ² , preferably 40-120 g / m ² , the bulk of the side layer (s) is 20-150 g / m ² , and the bulk of the laminate is 50-500 g / m ² , preferably 90-200 g / m ² .

A low-density bulk layer is advantageously produced by dry or wet laying of chemo-thermomechanical pulp (CTMM) or other “mechanical” pulp based on softwood, such as TMM, with a high degree of grinding. On the one hand, dry laying is preferred and any known laying method can be used, but irrespective of the degree of grinding of the pulp, determined on a Canadian standard device, should be more than 550, preferably more than 600, more preferably more than 650 and most preferably more than 700. Large the degree of grinding of the fibrous material for the first layer allows the sheet to shrink due to dehydration and hardening, without increasing the density to an undesirable value. The bulk layer may also include other fibrous raw materials having high wet elasticity, for example chemically crosslinked fibers, which, as a rule, have low resistance to dehydration and high elasticity after wet pressing, but such raw materials are not preferred, at least because for high cost.

Other suitable fibrous feedstocks are synthetic fibers, for example polyester, polyethylene and polypropylene fibers, which also have low dewatering resistance and high wet elasticity. In a preferred embodiment, the feed for a low-density layer forming a bulk layer, which is generally an intermediate layer in a laminate, is completely or substantially selected from the mechanically obtained so-called pulp with a high yield, i.e. pulp with a wood yield of at least 75%, it is possible with a yield of at least 80%, such as HTMM and TMM pulps essentially based on softwood, provided that they have the above grinding values.

Up to 25% of dry weight can also be added to the bulk layer. Here, by marriage is meant a rejected product from a paper or cardboard laminate, crushed into a liquid mass in a tear and consisting mainly of separated fibers.

The bulk layer also contains at least one binder, preferably latex, in an amount of 1-30%, preferably 5-30%, more preferably 7-30%, and most preferably 10-20% by weight of the laminate, calculated on dry weight .

According to one aspect of the invention, at least one of the side layers consists of bleached or unbleached sulphate, sulphite or organosoluble cellulose, which is obtained preferably from cellulosic raw materials, consisting mainly of soft and / or hardwood. The side layers may also contain one or more protective layers, for example, layers of metal foil, preferably aluminum foil, polymer film, metallized polymer film or varnish. The outermost layer, especially on the front side of the laminate, may consist of a film of any of the above materials with very good finishing.

If the packaging laminate has several lateral layers on the side of the bulk layer, which deepens along the line (lines) of collapse, then when crushing according to the proposed method, all of these side layers will be pressed into the bulk layer.

Another advantage of the invention related to the manufacture of a package by folding a laminate having crushing lines made according to the invention is that folding can be performed both in the direction of the recess forming the crushing line and in the direction away from this recess. When folding the laminate with the crushing lines obtained by the known method of crushing, bending should always be carried out in the direction from the recess made by the crushing device. Folding to the recess gives a great advantage, especially in the case of laminates, which have a good final surface finish and therefore are easily damaged and to which increased demands are placed on the quality of the front surface. In this case, it is possible to wrinkle the back of the laminate.

DESCRIPTION OF DRAWINGS

The invention is further described with reference to the accompanying drawings, in which

figa-D illustrate a known method of crushing the packaging laminate,

figure 2 depicts a slightly bent packaging laminate in a known method of crushing,

figure 3 depicts a side of a packaging laminate with a line of crushing according to the invention,

figure 4 depicts the laminate shown in figure 3, after folding along the line of collapse,

5 illustrates the folding of the most preferred packaging laminate crumpled according to the invention.

On figa-D shows how the crushing of a conventional packaging laminate in a known manner of crushing. On figa shows the crushing of the laminate by means of a creasing ruler and further explains the problems inherent in the prior art: residual deformation with the exit of the material from the plane in the known method of crushing (figv), the formation of a bulge / delamination on the folding line (figs) and increase thickness when folding 180 ° (fig.1D).

Figure 2 shows the initial fracture caused by compression in the side layer, which is subjected to compressive load in a known method of shearing. Then this kink will increase with the subsequent formation of the bulge shown in figs.

Figure 3 illustrates a method of crushing a packaging laminate according to the invention. The laminate comprises a volume-giving layer 1, a side layer 2b located on the first side of the laminate, and two side layers 2a, 3 on its second side. In this embodiment, the extreme side layer 3 on the second side of the laminate is a special surface layer with high quality finishing. The laminate is crushed by the crushing device 6, forming a line of collapse 4, and in the bulk layer a compacted section 5 is created in the zone of the line of crushing 4. Thus, the side layer 2b is pressed down into the bulk layer 1. On the second side, where the side layers 2a and 3 are located, the laminate remains flat due to the flat supporting tool 7 used in the crushing method.

Figure 4 shows how bending by 90 ° is carried out along the line 4 of the collapse. It can be seen that folding is carried out in the direction of the depressed layer 2b on the first side of the laminate. This means that the special and brittle lateral layer 3 will not be damaged during crushing or folding. It can also be seen that no bulge or similar deformation occurs at the folding line, and no delamination or cracking occurs.

Figure 5 presents a photograph under a microscope, which shows how in the most preferred laminate there is an indentation of the side layer into the bulk layer. Figure 5 illustrates the principle of the invention, which is generally described in figure 4.

The invention is not limited to the described options for its implementation and allows changes in the scope of the attached claims. For example, in some cases, a side layer may be absent on the side of the laminate, which is crushed by the crushing device, and the bulk layer is compacted without pressing the side layer into it. In addition, it is clear that the method is not limited to using a laminate with a bulk layer having certain values of the degree of grinding and certain coefficients of bending stiffness. This type of laminate is preferred for the practice of the present invention.

Claims (7)

1. A method of manufacturing a package by crushing and folding a packaging laminate made of cellulose fibers, containing a bulk layer (1) giving volume, and at least one side layer (2b) on at least one side of the bulk layer, the side layer and the bulk layer is directly or indirectly connected to each other on essentially all of its surfaces facing each other, including pressing in the first side of the laminate of the creasing device to form a crease line (4) and using it on the other sides e of the laminate opposite the first side of the supporting tool, which is essentially flat in the area corresponding to the location of the crushing device, characterized in that the laminate is folded along the crease line (4), wherein said bulk layer (1) consists of a mesh structure, formed by cellulose fibers. 2. A method of manufacturing a package according to claim 1, characterized in that the side layer (s) (2b) is located (located) on the first side of the laminate, and the side layer (2b) is pressed into the bulk layer along the crease line, and on the side opposite the pressed-in side layer (s) (2b), in the area of the crease line (4), the laminate is kept substantially flat. 3. A method of manufacturing a package according to claim 1 or 2, characterized in that in the bulk layer (1) in the area of the line of collapse (4) create a compacted structure (5), which facilitates folding along the line (4) of collapse essentially without the formation of bulges or delamination between the layers or without cracking in one or two extreme layers of the laminate (2b, 3) due to the formation of a crease line (4). 4. A method of manufacturing a package according to claim 1, characterized in that the bulk layer (1) contains up to 40-95% of cellulose fibers having a degree of grinding defined on a Canadian standard device, 550-950 ml; the density of the lateral layer (s) (2b) is higher than the density of the bulk layer, and the laminate has a bending stiffness coefficient calculated as the geometric mean for the longitudinal and transverse directions, more than 2.5 Nm ⁷ / kg ³ but less than 14 Nm ⁷ / kg ³ . 5. A method of manufacturing a package according to claim 1, characterized in that at least 60% of the bulk layer (1) consists of fibers having a grinding degree determined on a Canadian standard device of more than 600 ml, and the laminate has a bending stiffness coefficient of more than 3.0 Nm ⁷ / kg ³ , or more preferably at least 60% of the bulk layer (1) consists of fibers having a milling degree determined on a Canadian standard device of more than 650 ml, most preferably at least 700, but less than 850 ml, and the laminate has a bending stiffness coefficient of more than 4 , 0 Nm ⁷ / kg ³ , preferably more than 5.0 Nm ⁷ / kg. 6. A method of manufacturing a package according to claim 1, characterized in that the laminate is folded along the crease line (4) in the direction of its first side. 7. Packaging made by the method according to any one of claims 1 to 6.

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