FI98142C - Embossed wrapping paper - Google Patents

Abstract

Embossed wrapping paper, preferably sack paper, whose embossing pattern shows a plurality of out of the paper plane raised, delimited identical figures: (A) the figures are straight-lined, from each other separated and over the paper plane evenly distributed and provided with three, four or more sides and planar figure surface which is parallel to, and situated at a distance of 0.05-0.40 mm from the surrounding paper surface and with a total figure area that constitutes </= 40 % of the total paper area that has been embossed, and by that (B) the connection surface between figure surface and surrounding paper surface, substantially is perpendicular to the paper plane.

Description

98142

Embossed wrapping paper - Präglat omslagspapper 5 The production of sacks from embossed material is previously known. This is done mainly to increase the friction between the filled sacks which are stacked.

The embossing hitherto used in the sacks has meant that the sack material has had protrusions, and possibly also recesses, compared to the original level of the material. The idea has been that when stacked filled sacks, the protrusions are locked to those parts that are not raised (or recessed), 15 closest to the sack below. The classification of embossments previously used for sacks is: (i) the raised ridges extend over the width of the paper, possibly forming a checkered pattern in which only the edges of the checkers are raised. See e.g.

US-A-3,904,465 and 3,283,992 and SE-A-12949/65.

(ii) raised, limited and more or less large-patterned areas of paper. See, e.g., FR-A-2,353,207 (76,15678), DE-A-34 37,414, US-A-2,917,223, US-A-3,495,761 and US-A-3,411,698.

(iii) JP-A-112635/1986.

What many of these previously known embossments have in common is that they have a plurality of finite patterns raised from the paper plane 30 that are identical. It has been found that improvements are needed for patterned sack papers, e.g. for friction between stackable sacks. We have found that these requirements can be met if the pattern also has the following characteristics: 35 A. The patterns are rectilinear, spaced apart and evenly distributed in the plane of the paper, and equipped with 2, 98, 142, three, four or more sides and a planar pattern surface surrounding parallel to and spaced from the paper surface by 0.05 to 0.40 mm, comprising a total area of Figure 5 that is <40% of the total paper area.

B. The surface connecting the pattern surface and the surrounding paper surface is substantially perpendicular to the plane of the paper.

The pattern according to the above also has a friction-increasing effect on the wrapping paper when the articles wrapped in the paper are stacked on top of each other.

By wrapping paper according to the invention is meant paper in which the major part of the fibrous material (e.g.> 70 &, w / w) is usually derived from long-fiber wood such as pine or spruce. The fibrous material is usually a sulfate pulp and may be bleached or unbleached. More or less recycled fibers may be present. Several of the papers of this type referred to, e.g., sack paper, may be cro-packed. There are usually no fillers in the paper, and if they are present to some extent, the amount is usually <10% (w / w), such as <5% (w / w). Particularly important properties for the sack paper according to the invention are the refractive index, which should be> 0.4 kJ / kg in the longitudinal direction of the paper and> 0.3 kJ / kg in the transverse direction. The longitudinal elongation is usually> 1% (for somewhat better quality wrapping paper> 2%) and the transverse elongation is> 2% (preferably> 3.5%). The upper limits for these four properties are 7 kJ / kg, 6 kJ / kg, 20% and 15%, respectively. High values of refractive index and elongation indicate high-quality products. As a result, it cannot be ruled out that future development work will result in the upper limits being exceeded without going beyond what is considered sack paper according to the present invention. The fracture index and elongation values of 3 98142 shall be determined in accordance with ISO 1924 / 2-1985 (E).

In the following, the term 'longitudinal direction' = the machine direction of the paper, which in most cases is also the main direction of the fibers, applies. The transverse direction is perpendicular to the longitudinal direction.

The embossing patterns may be rectangular triangles (triangles), rectangles, pentagons, etc., with rectangles being preferred, and in particular those in which the sides are parallel in pairs, such as parallelograms, for example of the isosceles type. Examples of preferred rectangles are diamonds, including squares, rectangles and diagonals 15 (= parallelepiped that is neither equilateral nor rectangular). Usually, the patterning patterns according to the invention have an even axis of symmetry which is at most tetravalent. Within the same embossing, it is preferred that all patterns in the pattern be identical, although some patterns may have better friction between papers if they have 2, 3, 4 or more different patterns.

Identical patterns are evenly distributed on the patterned surface. This means that if a straight line is drawn over the surface of the paper, and if it is allowed to cut several patterns in the same way, then the distance between adjacent identical, line-cut patterns must always be the same. However, for the other corresponding lines 30, the corresponding distance need not be the same as for the first-mentioned line.

The paper of the invention may have, along one or both longitudinal sides, an outer zone from which 35 evenly distributed embossments are missing. Alternatively, the patterns in these zones may be less distinct because they do not rise as much from the original paper plane as the more central portions, or because the angle between the plane of the pattern and the plane of the original paper is greater than 90 °. Outer zones like this are 1-2 dm if present on the wrapping paper.

5

The normal patterning frequency is less than 500, such as less than 200 identical patterns / dm. An example is 10 to 100, such as 20 to 60 identical patterns / dm. The total pattern area is <40% and usually> 0.5% (preferably 10 over 1%) of the total pattern area. It has been shown that a very large improvement in the friction between the papers can be achieved if the total area of the patterns is less than 30%, such as less than 20% or less than 10% of the total area of the pattern.

15 Improved friction properties mean that the improvement is> 1%, such as> 5%, compared to the corresponding non-embossed paper (coefficient of friction between papers measured in any direction). The measurement method is presented in the experimental part.

20

If two identical papers according to the invention are placed face up, then substantially most of the identical patterns on the second paper (> 90%) should be located between the corresponding patterns on the other paper so that sliding becomes more difficult (friction increases) because the patterns on the other paper hit the other to the corresponding patterns on the paper. The maximum distance between two sides of the same pattern should therefore, in several more preferred embodiments, be greater than the shortest distance to the nearest pattern on the same paper. Said maximum distance is always the corner-to-corner distance, which in a rectangular triangle is always the side of the triangle, and which in the rectangular polygon is always a diagonal.

The orientation of the patterns in the pattern should preferably be such that the machine direction of the paper divides the angle of 35 5 98142 in the figures into substantially two (+/- 10%) equal angles. If there is a sharp angle in the figures, then preferably one is divided.

In a more preferred embodiment, the patterns are formed in parallelograms. These are shown in Figure A, and can be determined by the grid pattern that arises when the first number of parallel straight lines li, 12 / ΐ3 / ··· / 1η intersects the second number of parallel 10 straight lines l'i, 1'2 »l'3 , ..., l'n at an angle β. Straight lines extend across the entire width of the paper. n and n are integers, which may be even or odd, and always greater than 10. The exact number of lines is determined by the distance between them, their angle with respect to width 15, and the width of the sack paper. The perpendicular distance between the lines in the same group alternates, and is between li and I2 = a, and between l'l and 1'2 = c, 20 I2 and I3 = b, 1'2 and 1'3 = d, 13 and I3 = a, 1'3 and 1'4 = c, 14 and I5 = b, 1'4 and 1'5 = d, • · * · · · ln-1 and In = a or b, l'n-1 and l'n = c or d, 25 when n = even or when n = even or odd respectively odd integer, integer.

In general, the distances a, b, c and d <5 30 cm, preferably <3 cm, and that a <b and c <d. In an important embodiment, a = c and b = d, and preferably at the same time a <b. The patterns of the pattern are defined as the entire grid pattern minus the area located between the lines at distances b and d. In the most studied embodiment of the invention, on the priority day of the application, a, b, c and d are always> 0.05 cm, such as> 0.1 cm.

6 98142

The angle β satisfies the condition 10 ° <β <170 °, such as 10 ° <β <90 ° or 90 ° <β <170 °.

It is preferred that the lines l1, 12/13 /.../ In be at a positive angle of 5 and that the lines 1'1, 1'2, 1'3 /. ·., 1'η be at a negative angle to the machine direction of the paper. The angle β in the machine direction is easily divided into two equal parts.

Figures 1-6 show relevant examples seen from above. The machine direction of the paper is indicated by a double arrow [<--->] ·

Figure 1 shows a paper according to the invention, where a = c <b = d. The angle β is 60 °, and the pattern frequency is 39 pcs / dm2. The axis of symmetry is bivalent. The machine direction divides the angle β into two equal parts.

Figure 2 shows a similarly patterned paper with 20 a = c <b = d. The angle β is 30 °, and the pattern frequency is 28 pcs / dm2. The axis of symmetry of the figures is binary. The machine direction divides the angle β into two equal parts.

Figure 3 also shows a paper according to the invention in which a = c <b = d. The angle β is 30 °, and divided into two equal parts in the machine direction. The axis of symmetry of the figures is 2 bivalent. The pattern frequency is 48 pcs / dm.

Figure 4 shows a paper where a = c <b = d. The angle β is 30 °, and the machine direction divides it into an angle of 0 ° and another angle of 90 °. The axis of symmetry is tetravalent. The pattern frequency is 49 pcs / dm2.

Figure 5 shows a paper very similar to the one in the previous figure, but with smaller squares and a higher pattern frequency.

7 98142

Figure 6 shows a paper according to the invention in which a <c <b <d. The angle β is 90 °, and the machine direction divides it into two equal parts. The axis of symmetry of the figures is binary. The pattern frequency is 32 pcs / dm.

5

Production of paper according to the invention and device used in the production

One aspect of the invention is a method of making a wrapping paper, preferably sack paper, comprising a pattern as defined above by embossing a sack paper web. The paper web as such is manufactured by a method of making wrapping paper known per se, and in preferred embodiments of the invention means a creping step. The embossing-15 patterning is accomplished by allowing the paper web to pass, after possible creping, through the nip where one of the rolls is softer than the other (press roll and embossing roll, respectively).

20 The harder roll (embossing roll) has a jacket surface suitably made of metal (eg steel or cast iron) or other hard material. Its diaper surface has said pattern for the wrapping paper according to the invention, provided with evenly distributed, raised and identical patterns, with differences due to the fact that the diaper surface is not made of paper. From the aforementioned description of paper patterning, "paper" must be replaced by "jacket" or alternatively "jacket surface", and "machine direction of wrapping paper 30" by "lateral movement of jacket surface as the roll rotates about its axis". In general, the height of the patterns should be somewhat greater than the corresponding embossment in the embossed paper. The suitable spacing for the roll is therefore 0.06 to 0.45 mm instead of 0.05 to 0.40 mm 35 used on paper. The roll is designed so that it can be heated so that the paper dries as quickly as possible after embossing. Partly the paper then rises more easily from the roll and partly the embossing then stiffens more efficiently, which at the same time makes it more stable. It is therefore best if the roll is designed in the usual way as a drying machine for a paper machine, i.e. hollow and with 5 hot steam inlets (approximately 125-190 ° C) and condensate outlets and so-called "wing rods" to . The roll is suitably made of a roll provided with a soft jacket surface by smoothing out the recesses corresponding to the surface between the lines spaced b and d (see above). The depth of the recesses is in the range mentioned above.

The press roll is made of an elastic material which allows the patterns of the embossing roll to be completely struck into the material when the rolls are pressed against each other. An excellent material is rubber, e.g. hard rubber. The press roll is suitably bent to allow a uniform line pressure along it during embossing.

The appropriate embossing pressure (kp / cm) depends on such factors as the height of the patterns from the jacket surface, the hardness of the press roll, the thickness of the paper, the choice of fibrous material, the speed in the headbox, etc. The suitable embossing pressure is 1 to 10 kp / cm. In order to obtain an effective embossing which results in a stable embossing, the embossing should preferably be performed at a dry matter content of 60 to 80%, preferably 65 to 70% (w / w). After embossing, the paper is dried to a dry matter content of more than 90% (w / w).

Sack of the invention and its manufacture One aspect of the invention is a sack having all or part of the above-mentioned embossing on its surface. The sack material may be wholly or partly plastic or 9,98,142 paper. The patterning comprises a plurality of limited patterns elevated from the surface of the sack that are identical. Characteristic features are: 5 A. The patterns are rectilinear, spaced apart from each other and evenly distributed on the patterned surface, and provided with three, four or more sides and a planar pattern surface parallel to the surface of the surrounding sack and located at a distance of 0.05 to 0.40 mm, comprising a total area of the pattern which is <40% of the total area of the paper; and B. the surface connecting the pattern surface and the surrounding sack surface is substantially perpendicular to the surface of the sack.

15

Otherwise, the same applies to the sack as to the embossing of the paper, taking into account that the embossed surface does not have to be made of paper. If there is no machine direction on the embossed surface, it is meant by the papein machine direction in the height direction of the sack. If the surface of the sack is only partially covered with embossing, it is suitably located above or below the sack, i.e. on those sides of the sack which are against other sacks when stacked.

The sack according to the invention is designed for sacks in a manner known per se, in which case the sack material can comprise one to six different layers, so-called sheets, the outermost sheet of which according to the invention is preferably made of paper. The embossing is located in the outer layer 30, or alternatively it is glued on top in the form of an embossed plastic or paper sheet.

In the manufacture of sacks, it is customary to start from one or more web-shaped rolls of sack-35 material that are as wide as the circumference of the sack, including the portion (e.g., adhesive joints) used to form the web material into a longitudinal tube. A roll is used for each sheet, in which case the web material (outer web) coming to the outside of the bag must be embossed with one of the above-mentioned patterns, or, if not, it is moistened, embossed and dried during unwinding. The various web materials are continuously placed on top of each other during unwinding, after which the web material of the possibly multiple sheets thus obtained is continuously shaped and joined together into a 10 (glued together) tube. This is later cut into suitable sack lengths, after which the other end of each length is joined together to form the bottom of the sack. Alternatively, the web material is cut to the length of the sack, which is then joined together into a tube and sealed at one end.

Various aspects of the invention are also clarified in the claims which form part of the description.

20 Experimental Part 1. Summary

The sack paper taken from the paper machine with a dry matter content of approximately 65% is embossed in a laboratory press under conditions designed to correspond as closely as possible to the embossing of the paper machine.

Static friction between the embossed papers 30, tensile strength, flexibility, breaking work and air resistance were tested.

Friction increases as the breaking work decreases and the air resistance decreases due to the embossing of the sack paper. Based on the test results, Figures D, large squares, B, 35 elongated sparse diamonds, C, elongated dense diamonds, and elongated rectangles, respectively, are recommended.

11 98142 2. Application in practice 2.a. Embossing 5 The paper in the form of sheets was taken from the paper machine with a dry matter content of approximately 65% during the quality change. The sheets were stored in plastic bags to prevent them from drying until embossing was completed.

10 The sheets of paper were embossed under static conditions in a laboratory press using a steel plate provided with the desired pattern. The studied patterning is shown in Figures 1-6. Embossing was performed at a pressure of 3 kp / cm for 1 s and 5 s.

15

The sheets were then dried against a drying cylinder between two rigid sheets of blotting paper so that they remained stretched.

20 2.b. Tensile stress, elongation, fracture work were determined in ISO

1924 / 2-1985 (E), and air resistance according to ISO 3687-1976.

2.c. Determination of the coefficient of friction 25 This was performed according to TAPPI T: 503 using an inclined plane supplied by Buchel van der Korpat, The Netherlands. Friction, the top surface against the bottom surface, was determined between two strips cut from the treated sheets 30 longitudinally and transversely, respectively. The experiments were repeated five times for each pattern. The averages [Mv] of the friction coefficients obtained are shown in Table 1. By cutting the strips in the other direction and / or fitting them in some other way, the coefficients of friction can also be determined for other directions of the sack paper.

12 98142 3 «Results

The embossing hardly affects the tensile strength at all, while the elongation seems to increase somewhat, leading to a reduction in fracture work of up to 20% in the longitudinal direction and up to 16% in the transverse direction.

The air resistance increases by up to 12 units, from 29 to 41 s. 10 Friction increases by up to 0.11 units from 0.63 to 0.74.

15 20 25 30 il m i «itu i: j ja.

35 13 98142

Table g

<U Z <N

«Ex g e

'X -H -H

-H Λ K) 1-3 M O

• H «CU 3 3 tl P M etl O <#>: 0 p tl cC33t-i> i BIO)

3 -H P P cm 3: «P rt X

O tn 01 g ^ g O> «

• H -H -H O O Pi -M rt X

> Sh ti ^ 4- »C ti g P

3 3 3 Dj 4) O) 3 r-1 -H

«CU CU X>> 2 M *

Figure sec. pit.poikk. pit.poikk. pit.poikk. sec.

10 1 13 7.16 3.04 2.78 10.64 127 233 37.7 0.67 1 5 3 6.51 3.38 2.93 11.20 124 267 37.8 0.61 2 1 3 6.50 2.95 2.85 9.93 117 214 34.0 0.70 2 5 3 7.01 3.06 2.87 9.63 126 213 36.5 0.68 3 1 3 6.62 2.90 2.92 10.14 123 218 35.7 0.72 15 3 53 6.36 3.03 2.68 11.05 10e 242 41.2 0.67 4 1 3 7.00 3.00 3.19 11.37 137 248 35.3 0.72 4 53 7.06 2.97 2.88 10.43 126 225 36.1 0.74 5 1 3 6.63 2.88 2.84 10.00 119 215 28.5 0.62 5 5 3 6.97 3.01 3.05 10.08 133 221 35.9 0.64 20 6 1 3 6.59 3.03 2.90 9.87 122 216 30.3 0.68 6 53 6.57 3.22 2.74 11.42 114 256 35.9 0.68 0 00 6.86 3.18 3.24 11.22 139 254 28.9 0.63 25 • 2 Figure 1 = Diamonds 4x6 mm , 39 pcs / dm 2

Figure 2 = Diamonds 3x9 mm, 28 pcs / dm 2

Figure 3 = Diamonds 3x9 mm, 48 pcs / dm t 2 Figure 4 = Squares 5 mm, 49 pcs / dm 30 Figure 5 = Squares 3.5 mm, 49 pcs / dm2 2 'Figure 6 = Rectangle, diagonal, 32 pcs / dm

Figure 0 = Paper without embossing 35

Claims (5)

1. Embossed packaging paper, preferably sack paper, whose embossing pattern exhibits a plurality of identical, raised figures, raised from the paper's pane, characterized in that the A. figures are rectilinear, spaced apart and evenly distributed over the paper plane, and provided with three or more four, sides and pian figure surface which are parallel to and located at a distance of 0.05-0.40 mm from the surrounding paper surface and with a total figure surface constituting s 40%, preferably s 20%, of the total paper surface which is embossed, and that B. The bonding surface between the figure surface and the surrounding paper surface is substantially perpendicular to the paper plane. 35 2. Embossed packaging paper according to claim 1, characterized in that the figures are parallelograms defined as squares in the grid pattern that arise if a number of parallel lines (llf 12, 13, ..., ln) are crossed by a number of other parallel lines (l'lf 1'2, 1'3 /.., l'n) at an angle β, where n and n 'are integers greater than 10 and where the perpendicular distance between 5 1, and 12 = a , and between 1 'and 1'2 = c, 12 and 13 = b, 1'2 and 1'3 = d, 13 and 14 = a, 1'3 and 1'4 = c, 14 and ls * b , 1'4 and l's = d, 10 ln.] And ln = a or b, l'n., And l'n = c or d, for n = an even and a. for n = an even or a. odd integers, odd integers, where the figures in the pattern are defined as the total area over which the lines extend minus the area between lines with spaced b and d from each other, and where a, b, c, d are selected such that a and cs d. 3. Embossed packaging paper according to claim 2, characterized in that a = c and b = d, preferably with a s b. Embossed packaging paper according to any one of claims 2 - 3, characterized in that the lines 1, 12, 13,. . . , ln has positive slope and lines 1 ', 1'2, 1'3 ,. . . The 1 has a negative slope to the machine direction of the paper, preferably with the same absolute value and that the winkin is 10 ° <β <170 °, preferably 10 ° <S <90 °. Embossed packaging paper according to claim 1, characterized in that a corner-to-corner distance, where applicable a diagonal distance, in each figure is longer than the shortest distance to the nearest figure.