EP0464470B1 - Crêpe paper, process for making the same, and use - Google Patents

Abstract

The present invention relates to crêpe papers which, in addition to high elongation, also show high smoothness. Such crêpe papers can be formed as raw paper, impregnated paper and as impregnated and coated paper. The papers according to the invention can be produced by a process which is characterised by a special scraper and a special angle of attack of the scraper on the crêpe cylinder. The papers thus produced can advantageously be used in the manufacture of adhesive tapes and covering tapes and for the manufacture of labels, especially for marking shaped articles.

Description

The invention relates to crepe papers, processes for their production and their use.

In papermaking, higher stretchability of the paper coming from the paper machine (generally 2 to 4%) can be obtained by creping the paper web. Here, the damp web adhering to the surface of a cylinder is removed by a scraper lying against the cylinder. A difference in the drive speed of the creping cylinder and the subsequent transfer and drying unit, which can be set to approximately 10 to 50%, causes the paper web to be "creped" by this amount, ie shortened by producing fine folds. This process can be carried out both inside (wet crepe) and outside the paper machine (dry crepe). With dry creping, the rewetted paper web is processed on special creping machines. The fine pleating across the machine equipment results in the great elasticity of the crepe paper, which is used in the sanitary and hygiene sectors for the manufacture of handkerchiefs, towels, serviettes, diapers and toilet paper, but also for the production of adhesive and masking tapes. The crepe papers are usually Made from high-quality cellulose but also from (un) bleached ground wood together with common additives while maintaining the desired thickness and the intended basis weight.

According to the method of the prior art, the wet crepe paper is pressed by a press at high pressure onto the crepe cylinder, from which it is then removed with a scraper at a dry content of approx. 40%. The speed differences to the following paper machine parts (e.g. transfer device and drying cylinder) result in the degree of crepe. Such a method has long been known and e.g. in US-A-1 772 185 and US-A-2 940 591. The scrapers usually used in accordance with the above method have a grinding angle which is in the range from 20 ° to 90 °. Furthermore, the height of the scraping edge is 0.2 to 0.4 mm. The angle between the tangent and the scraper at the point of contact of the scraper with the crepe cylinder is 10 ° to 30 ° in the usual method. The above design of the scraper and the angle of attack cause the paper to be blocked and compressed when scraped off, resulting in the typical "crepe mountains" and "crepe valleys".

According to this method, crepe papers are produced which have a significantly increased elongation compared to the papers taken off directly from the paper machine. However, these crepe papers have a low smoothness, which means that the adhesive application is very high in the production of adhesive tapes in order to obtain sufficient adhesive strength. Furthermore, the low smoothness of the crepe paper means that the fingers and the skin are often affected during use. Finally, the poor smoothness of the paper leads to unsatisfactory printability.

According to US-A-2 941 661, an impregnated crepe paper with a fine crepe, with rounded crepe edges on one side and with a flatter opposite side is described. The surface smoothness of the paper is created by adding water-dispersible, deacetylated karaya gum to the paper pulp.

EP-A-0 213 596 comprises a crepe paper made from a substrate with a fine crepe pattern which has been smoothed by calendering. The substrate is saturated with a soft, stretchable polymer, resulting in a paper with an elongation of 15 to 25% and a Sheffield smoothness in the range of 20 to 250. The basis weight of the above substrate is in the range of 30 to 75 g / m ² .

The object of the present invention is to create crepe papers which, in addition to being highly stretchable, have a high degree of smoothness.

Another object of the invention is to provide a method with which crepe papers with the above properties can be produced, additional process steps or addition of further chemicals to the paper pulp should be prevented as far as possible.

The above task with regard to paper properties can be achieved by using a crepe paper with a thickness (DIN 53105) of 0.07 to 0.18 mm, a mass per unit area (DIN 53104) of 25 to 80 g / m ² and an elongation at break (DIN 53112) of 10 to 16% and a Bekk smoothness (DIN 53107) of 2.5 to 6 seconds on the sieve side and from 1.0 to 3.0 seconds on the top can be solved, this raw crepe paper can be obtained by using the paper web running the crepe cylinder with a scraper with a grinding angle of 20 ° to 60 ° and a crepe scraper edge of 0.01 to 0.02 mm height, the scraper being set at an angle of 35 ° to 45 ° with respect to the tangent to the crepe cylinder , decreases, leads over the surface of the scraper to a transfer device and then onto a drying cylinder.

In a preferred embodiment, the raw crepe paper has a Bekk smoothness of 3 to 6 seconds, in particular 4 to 6 seconds, and on the top side 1.2 to 3 seconds, in particular 2 to 3 seconds.

The mass per unit area (DIN 53104) of the crepe paper is preferably 30 to 60 g / m ² , and the Breaking strength (dry, according to DIN 53112) advantageously has values in the longitudinal direction of 26 to 50 Newtons / 15 mm and in the transverse direction of 12 to 25 Newtons / 15 mm.

Another special version of the raw crepe paper is characterized in that the tightness according to Gurley is 6 to 12 s.

According to the present invention, an impregnated crepe paper with a thickness (DIN 53105) of 0.07 to 0.18 mm, a mass per unit area (DIN 53104) of 40 to 120 g / m ² , preferably 50-90 g / m ² , an elongation at break (AFERA 4005) of 8 to 20% and a smoothness which according to Bekk (DIN 53107) is 7 to 20 seconds on the sieve side and 2 to 8 seconds on the top side, which is characterized in that the Impregnated crepe paper is available by cutting the paper web running on the crepe cylinder with a scraper with a grinding angle of 20 ° to 60 ° C and a crepe scraper edge of 0.01 to 0.02 mm in height, the scraper at an angle of 35 ° to 45 ° with respect to the tangent to the crepe cylinder, decreases, leads over the surface of the scraper to a transfer device and then onto drying cylinders, impregnated and optionally coated.

Special configurations of the impregnated crepe paper are characterized in that the breaking strength (dry, according to AFERA 4004) in the longitudinal direction 40 to 120 N / 15 mm, preferably 40-90 N / 15 mm, and in the transverse direction 15 to 60 N / 15 mm, preferably 15-40 N / 15 mm.

The impregnation of the crepe paper is preferably based on aqueous dispersions based on styrene butadiene, polyvinyl acetate, acrylate or acrylonitrile or mixtures of these with an application amount of 10 to 40 g / m ² .

In a special embodiment of the crepe paper, a "release coat" is applied to the top of the impregnated paper, which preferably contains an aqueous dispersion based on acrylate, polyvinyl acetate, long-chain fatty acid and / or fatty alcohol derivatives, paraffins or silicone compounds or mixtures thereof in an advantageous amount of 2 to 10 g / m ² .

Another variant of the impregnated crepe paper is finally given by the fact that a primer is applied to the sieve side, which preferably consists of a dispersion based on natural latex, acrylonitrile, styrene butadiene or acrylate or mixtures of these in an amount of 2 to 5 g / m ² exists.

Finally, according to the present invention, impregnated papers are also included which have a "release coat" on the top and a primer on the screen side. The "release coat" means that the adhesive tape can be unwound again from the roll without sticking to the top of the underlying roll tape. Finally, the primer requires the adhesive to adhere well to the screen side.

The crepe base papers and refined crepe papers according to the invention can be produced by a method in which the paper web guided on the crepe cylinder is lifted off with a scraper, passed over the surface of the scraper to a transfer device and from there to the drying cylinders, and optionally impregnated and coated, which characterized in that the grinding angle of the scraper is 20 ° to 60 °, the scraper edge has a height of 0.01 to 0.02 mm, and the angle between the tangent and the scraper at the point of contact of the scraper with the crepe cylinder 35 ° to Is 45 °.

Advantageously, the above method is carried out so that the speed of the Transfer device compared to that of the creping cylinder is delayed by 15 to 20%.

The scraper material is also preferably made of stainless steel.

The impregnation can take place in an immersion bath, after which it is squeezed off with rollers.

The "release coat" and primer coating is generally carried out using an air brush, a "Mayer Bar", a "Speed Sizer", a roller doctor blade, an anilox roller or a "blade coater".

The invention further includes the use of the crepe papers according to the invention for the production of adhesive and masking tapes.

Finally, the crepe papers according to the invention can also be used for the production of printed labels for the marking of shaped articles.

Fig. 1:

Kreppvorrichtung zur Kreppapierherstellung;

Fig. 2:

Schaber;

Fig. 3a:

Glätte nach Bekk auf der Siebseite des Kreppapiers in Abhängigkeit von der Dehnung;

Fig. 3b:

Glätte nach Bekk auf der Oberseite des Kreppapiers in Abhängigkeit von der Dehnung;

Fig. 4a:

Glätte nach Bekk auf der Siebseite des Kreppapiers in Abhängigkeit von dem Flächengewicht; und

Fig. 4b:

Glätte nach Bekk auf der Oberseite des Kreppapiers in Abhängigkeit von dem Flächengewicht.

The invention is illustrated by the following figures and the example.

Fig. 1:

Creping device for crepe paper production;

Fig. 2:

Scraper;

Fig. 3a:

According to Bekk smoothness on the screen side of the crepe paper depending on the stretch;

3b:

Bekk smoothness on top of crepe paper depending on stretch;

Fig. 4a:

Bekk smoothness on the screen side of the crepe paper depending on the basis weight; and

Fig. 4b:

Bekk smoothness on the top of the crepe paper depending on the basis weight.

The crepe device used according to the invention for producing the crepe paper is shown in FIG. 1. The scraper (2), which is provided with a cover sheet (3), bears against the crepe cylinder (1). The scraper is connected to the scraper holder (4), which in turn is attached to the scraper bar (5).

The design of the scraper is illustrated in Figure 2. The front of the scraper has a grinding surface (6) and a scraping edge (7) which, according to the present invention, have a special grinding angle or a defined height.

In FIGS. 3a, 3b, 4a and 4b, the Bekk smoothness of a finished crepe paper (0) according to the present invention is compared with the smoothness of commercially available products (I) to (VII). The representations show the superiority of the crepe papers according to the invention in terms of smoothness and at the same time high elongation, this superiority being particularly evident on the wire side. The crepe paper according to the invention was impregnated with an aqueous dispersion based on styrene butadiene in an amount of 15 g / m ² . Furthermore, there was a "release coat" on the top based on an aqueous dispersion of acrylate and fatty alcohol derivatives in an application quantity of 4 g / m ² .

Finally, a primer was applied to the sieve side in an amount of 2 g / m ² , which was composed of an aqueous dispersion of natural latex, acrylonitrile and styrene butadiene. The base paper used corresponded to that of the following example.

Example:

A paper mass formed on a paper machine in the usual way from half-bleached sulfate pulp was passed onto a crepe cylinder and removed from there by means of a scraper. This scraper had a grinding angle of 41 °, a scraping edge with a height of 0.02 mm and was set at an angle of 6 ° with respect to the horizontal on the cylinder at the point of contact. Furthermore, the speed difference between the creping cylinder and the subsequent transfer device was 18%, i.e. the transfer device moved relative to the cylinder with a delay of 18%. The speed of the drying cylinder following the transfer device and the paper rewinder were increased again compared to the transfer device. The speed deceleration between the crepe cylinder and the first drying cylinder was only 12.5% and between the crepe cylinder and the paper rewinder was 9.5%.

Using the above process, a raw crepe paper was obtained, which is characterized by the following data:

The foregoing outlines the advantages that can be achieved with the present invention. The crepe paper produced by the method according to the invention has not only a high elongation but also a high smoothness. This can greatly reduce the application of adhesive, particularly on the screen side of the paper, in the production of adhesive tapes and masking tapes. In order to achieve the same adhesive strength as with conventional crepe papers, at least 30% adhesive can be saved. As a result, the manufacturing costs for the adhesive tapes are greatly reduced and the productivity of the manufacturing process increases significantly. The significantly higher smoothness compared to normal crepe paper also means that the fingers and skin of the user are better protected when using the crepe paper. Finally, the masking tapes adhere better to one another. The high smoothness, combined with a smaller application amount of adhesive and thus a smaller thickness of the adhesive tape, also means that sharp lacquered edges can be produced at the junction between coated and covered areas with adhesive tape.

Due to the simultaneous properties of high elongation and excellent smoothness, a new application opens up for the crepe papers produced in this way. The high smoothness means that the crepe paper can now be easily printed, on the other hand, the high elongation of the paper offers the Possibility to stick even complicated shaped parts with this paper. The crepe papers according to the invention can thus advantageously be used as labels for even complicated shaped articles.

Claims (18)

1. Base crepe paper with a thickness (DIN 53105) of 0.07 to 0.18 mm, a mass per unit area (DIN 53104) of 25 to 80 g/m², an elongation at rupture (DIN 53112) of 10 to 16%, a Bekk smoothness (DIN 53107) of 2.5 to 6 seconds on the wire side and 1 to 3 seconds on the top side, characterised in that the base crepe paper is obtainable by removing the paper web moving on the crepe cylinder with a ductor with a drag angle of 20° to 60° and a crepe ductor edge (7) 0.01 to 0.02 mm high, wherein the ductor is set at an angle of 35° to 45° relative to the tangent to the crepe cylinder, and passing it over the surface of the ductor to a transfer device and then onto a drying cylinder.
2. Base crepe paper according to claim 1, characterised in that the Bekk smoothness is 3 to 6 seconds, in particular 4 to 6 seconds, on the wire side, and 1.2 to 3 seconds, in particular 2 to 3 seconds, on the top side.
3. Base crepe paper according to claim 1 or 2, characterised in that the mass per unit area (DIN 53104) is 30 to 60 g/m².
4. Base crepe paper according to one or more of the preceding claims, characterised in that the rupture force (dry, according to DIN 53112) is 26 to 50 N/15 mm in the longitudinal direction and 12 to 25 N/15 mm in the transverse direction.
5. Base crepe paper according to one or more of the preceding claims, characterised in that the Gurley density is 6 to 12 seconds.
6. Impregnated crepe paper with a thickness (DIN 53105) of 0.07 to 0.18 mm, a mass per unit area (DIN 53104) of 40 to 120 g/m², an elongation at rupture (AFERA 4005) of 8 to 20%, a Bekk smoothness (DIN 53107) of 3 to 20 seconds on the wire side and 2 to 8 seconds on the top side, characterised in that the impregnated crepe paper is obtainable by removing the paper web moving on the crepe cylinder with a ductor with a drag angle of 20° to 60° and a crepe ductor edge (7) 0.01 to 0.02 mm high, wherein the ductor is set at an angle of 35° to 45° relative to the tangent to the crepe cylinder, passing it over the surface of the ductor to a transfer device and then onto a drying cylinder, impregnating it and if occasion arises coating it.
7. Impregnated crepe paper according to claim 6, characterised in that the Bekk smoothness is 7 to 20 seconds on the wire side and 3 to 8 seconds on the top side.
8. Impregnated crepe paper according to claim 6 or 7, characterised in that the rupture force (dry, according to AFERA 4004) is 40 to 120 N/15 mm, preferably 40 to 90 N/15 mm, in the longitudinal direction, and 15 to 60 N/15 mm, preferably 15-40 N/15 mm, in the transverse direction.
9. Impregnated crepe paper according to one or more of the preceding claims 6 to 8, characterised in that the impregnation includes aqueous dispersions based on styrenebutadiene, polyvinyl acetate, acrylate or acrylonitrile or mixtures thereof in a coating quantity of 10 to 40 g/m².
10. Impregnated crepe paper according to one or more of the preceding claims 6 to 9, characterised in that a release coat is applied to the top side.
11. Impregnated crepe paper according to claim 10, characterised in that the release coat contains a dispersion based on acrylate, polyvinyl acetate, long-chain fatty acid and/or fatty alcohol derivatives, paraffin or silicone compounds or mixtures thereof in a coating quantity of 2 to 10 g/m².
12. Impregnated crepe paper according to one or more of the preceding claims 6 to 11, characterised in that a primer is applied to the wire side.
13. Impregnated crepe paper according to claim 12, characterised in that the primer includes aqueous dispersions based on natural latex, acrylonitrile, styrene butadiene or acrylate or mixtures thereof in a coating quantity of 2 to 5 g/m².
14. Method for the manufacture of crepe paper according to any of claims 1 to 13, wherein the paper web moving on the crepe cylinder is removed with a ductor, passed over the surface of the ductor to a transfer device and then onto a drying cylinder and if occasion arises impregnated and coated, characterised in that

    (1) the ductor has a drag angle of 20° to 60° and a ductor edge (7) 0.01 to 0.02 mm high, and

    (2) the ductor is set at an angle of 35° to 45° relative to the tangent to the crepe cylinder at the point of contact with the ductor.
15. Method according to claim 14, characterised in that the transfer device is retarded in speed by 15 to 20% relative to the crepe cylinder.
16. Method according to claim 14 or 15, characterised in that the ductor is made of special steel.
17. Use of the crepe papers according to any of claims 1 to 13 for the manufacture of adhesive and masking tapes.
18. Use of the crepe papers according to any of claims 1 to 13 for the manufacture of labels, in particular for marking shaped articles.

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