Method for the Continuous Coating of a Cellulose-Based Fibrous Substrate Web with Fatty Acid Chloride

Abstract

The present invention concerns a process for continuously coating a cellulose-based fibrous substrate web with fatty acid chloride, comprising the steps of a) pre-drying a cellulose-based fibrous substrate web to an EN ISO 638:2008 dry matter content of less than 10%; b) coating the cellulose-based fibrous substrate web pre-dried in step a) with a liquid fatty acid chloride composition at a DIN EN 20187 relative humidity of less than 20 rH and a temperature below the boiling temperature of the liquid fatty acid chloride composition; c) thermally treating the coated cellulose-based fibrous substrate web obtained from step b).

Claims

1.-12. (canceled)

13. A method for continuous coating of a cellulose-based fibrous substrate web with fatty acid chloride, comprising the steps of: (a) pre-drying a cellulose-based fibrous substrate web to a moisture content in accordance with EN ISO 638:2008 of less than 5%; (b) coating the pre-dried cellulose-based fibrous substrate web from step (a) with a liquid fatty acid chloride composition at a relative humidity in accordance with DIN EN 20187 of less than 20% rH and a temperature below the boiling temperature of the liquid fatty acid chloride composition; (c) contact-free thermal treatment of the coated cellulose-based fibrous substrate web from step (b).

14. The method according to claim 13, wherein the liquid fatty acid chloride composition contains a fatty acid chloride selected from the group consisting of aliphatic mono carboxylic acid chlorides with 6 to 26 carbon atoms, and mixtures thereof.

15. The according to claim 14, wherein said fatty acid chloride is selected from the group consisting of aliphatic mono carboxylic acid chlorides with 16 to 20 carbon atoms, and mixtures thereof.

16. The method according to claim 14, wherein the fatty acid chloride is selected from the group consisting of aliphatic saturated fatty acid chlorides with 6 to 26 carbon atoms, and mixtures thereof.

17. The according to claim 16, wherein the fatty acid chloride is selected from the group consisting of aliphatic saturated fatty acid chlorides with 16 to 20 carbon atoms, and mixtures thereof.

18. The method according to claim 1, wherein the liquid fatty acid chloride composition contains at least 5% by weight fatty acid chloride with respect to the total weight of the fatty acid chloride composition.

19. The method according to claim 13, wherein the liquid fatty acid chloride composition contains more than 95% by weight fatty acid chloride with respect to the total weight of the fatty acid chloride composition.

20. The method according to claim 13, wherein at least one of steps (a) to (c) is carried out in an enclosed atmosphere with a dry air flow with a relative humidity in accordance with DIN EN 20187 of less than 20% rH.

21. The method according to claim 13, wherein the coating in step (b) is carried out with a roll application method.

22. The method according to claim 21, wherein said roll application method is an offset gravure method

23. The method according to claim 13, wherein the coating in step (b) is carried out with a total application in the range from 0.1 to 10% by weight with respect to fatty acid chloride per g/m.sup.2 basis weight of the cellulose-based fibrous substrate web.

24. The method according to claim 13, wherein the thermal treatment of the coated cellulose-based fibrous substrate web in step (c) is carried out by radiation treatment.

25. The method according to claim 24, wherein said radiation treatment comprises an infrared radiation drying.

26. The method according to claim 13, wherein the coated and thermally treated cellulose-based fibrous substrate web obtained from step (c) is post-treated in a further step (d) in a dry air atmosphere with a relative humidity in accordance with DIN EN 20187 of less than 20% rH.

27. A coating device for the continuous coating of a cellulose-based fibrous substrate web with a liquid fatty acid chloride composition according to claim 13, comprising: a pre-drying module; a coating module and a thermal post-treatment module, wherein at least one of the modules of the coating device is enclosed and has an atmosphere of dry air with a relative humidity in accordance with DIN EN 20187 of less than 20% rH.

28. Use of a cellulose-based fibrous substrate web obtained by the method as defined in claim 13 for the production of a product selected from the group consisting of corrugated board base paper, packaging paper, carton, paperboard, hygienic paper, tissue, printing paper, writing paper, and combinations thereof.

Description

DESCRIPTION OF THE FIGURES AND EXAMPLES

[0049] The invention will now be explained below using FIGS. 1 to 3 and the following example 1, without being limited to these embodiments.

[0050] FIG. 1 shows a magnified detail of FIG. 2 with the utilized modules of the method according to the invention,

[0051] FIG. 2 schematically shows a modular arrangement of the method according to the invention,

[0052] FIG. 3 schematically shows an embodiment of the coating module according to the invention as a three-roll application device.

[0053] In FIGS. 1 to 3 the following reference numerals are used: [0054] A unwinding module [0055] B pre-drying module [0056] C coating module [0057] D first thermal post-treatment module [0058] E second thermal post-treatment module [0059] F winding module [0060] G dry air inlet [0061] H washing module [0062] I ambient air inlet [0063] J air outlet [0064] 1 metering roll [0065] 2 transfer roll [0066] 3 fibrous substrate carrier roll [0067] 4 impregnation bath [0068] 5 storage tank [0069] 6 application film [0070] 7 fibrous substrate web [0071] 8 collection tank [0072] 9 waste tank

[0073] FIG. 1 shows a magnified detail of FIG. 2 with utilized modules of the method according to the invention. The cellulose-based fibrous substrate web is pre-dried in a pre-drying module B, in particular to a dry content of less than 10% in accordance with EN ISO 538:2008. In a coating module C, the pre-dried cellulose-based fibrous substrate web is coated with a liquid fatty acid chloride composition; in particular, a three-roll application device using the gravure method is used. A first thermal post-treatment module D is particularly formed by a radiation drier and heats the cellulose-based fibrous substrate web coated with the liquid fatty acid chloride composition, particularly with infra-red radiation.

[0074] FIG. 2 schematically shows a modular arrangement of the method according to the invention. The cellulose-based fibrous substrate web runs through the subsequently arranged modules. With an unwinding module A the cellulose-based fibrous substrate web is unwound particularly from a (paper) reel. Then the cellulose-based fibrous substrate web is pre-dried in the pre-drying module B. In the coating module C, the pre-dried cellulose-based fibrous substrate web is coated with a liquid fatty acid chloride composition and is tempered in a first thermal post-treatment module D. In a second thermal post-treatment module E, the coated cellulose-based fibrous substrate web is adjusted to the temperature conditions desired for further processing. In addition, the second thermal post-treatment module E serves as a kind of gate to separate a dry atmosphere in modules B to E from, for example, a more humid ambient air atmosphere. The provision of the second thermal post-treatment module E is optional. Coming from the second thermal post-treatment module E, the coated cellulose-based fibrous substrate web is wound up in a winding module F. According to the invention, the modules B to E are supplied from a dry air inlet G. After the dry air has flowed from the dry air inlet G through modules B to E, it is guided over one or more washing module(s) H, in which residual hydrochloric acid is washed out and released to the atmosphere through air outlet J. The winding module F is flushed with atmospheric air from the ambient air inlet I, then guided over one or more washing module(s) H and then released to the atmosphere via air outlet J.

[0075] FIG. 3 schematically shows an embodiment of the coating module C according to the invention as a three-roll application device. In this regard, coating of a cellulose-based fibrous substrate web 7, particularly a paper, paperboard or cardboard web, is carried out in a contact operation employing the offset gravure method. A liquid fatty acid chloride composition is transferred from a storage container 5 into an impregnation bath 4. A metering roll 1 is running in the impregnation bath 4. The metering roll 1 is, for example, a roll coated with ceramic and engraved by laser with a low specific cell volume in the range from 1 to 10 μm cell depth. The metering roll 1 transports a certain quantity of fatty acid chloride composition from the impregnation bath 4, depending on the set parameters, for example, the cell volume and the rotational speed, and transfers it to a transfer roll 2, wherein a layer of fatty acid chloride composition is formed on the transfer roll 2 with a certain layer thickness. This layer of fatty acid chloride composition is transferred from the transfer roll 2 as an application film 6 to a cellulose-based fibrous substrate web 7, wherein the cellulose-based fibrous substrate web 7 is guided around a fibrous substrate carrier roll 3. Surplus fatty acid chloride composition is collected in a collection tank 8 and flows into a waste tank 9.

EXAMPLES

[0076] In the following examples, tallow fatty acid chloride 50/50 from BASF SE, was used. This fatty acid chloride composition consists of 50% by weight of palmitoyl chloride (CAS number 112-67-4) and of 50% by weight of stearoyl chloride (CAS number 112-76-5).

[0077] The base paper used in the examples was a brown, unsized test liner from Thurpapier—Model Management AG in Weinfelden, and had a basis weight of 130 g/m.sup.2 and a Cobb.sub.60 value of 159 g/m.sup.2.

[0078] In the following examples, palmitoyl chloride (CAS number 112-67-4) from BASF SE was used. Instead of this, a fatty acid chloride composition can also be used, which consists of 50% by weight of palmitoyl chloride and of 50% by weight stearoyl chloride (CAS number 112-76-5).

[0079] The base paper used in the examples was a brown, unsized test liner from Thurpapier—Model Management AG in Weinfelden and had a basis weight of 130 g/m.sup.2 and a Cobb.sub.60 value of 159 g/m.sup.2.

[0080] The experimental set-up 1 for examples 1 to 4 was as follows. The base paper was pre-dried with contact drying at 60° C. and 5% rH to a dry content >96% (in accordance with EN ISO 638:2008). At the same temperature and humidity, the dried base paper was coated with fatty acid chloride with a roll application device (ZIL2140 Zehntner-Ink-Lox) employing an offset gravure method with a speed of 5 m/min. The gravure roll had 180 grid per cm at an angle of 45° and a specific cell volume of 3.8 cm.sup.3/m.sup.2. The pressing force between the gravure roll and the transfer roll was 56 N/m. The transfer roll, made from rubber, had a Shore-A hardness of 40 and was pressed against the paper substrate with a line load of 152 N/m. The applied amount was 1 to 3 g/m.sup.2. The coated paper substrate was then treated with two Krelus IR radiators (G7-50-2.5) for 12 seconds at 42 kW/m.sup.2.

Example 1

[0081] The treatment of the base paper was carried out analogously to experimental set-up 1, with the difference that the base paper was pre-dried with contact drying at 110° C. and about 5% rH to a moisture content of 1.7% (in accordance with EN ISO 638:2008). The paper treated in this manner had a Cobb.sub.60 value of 19 g/m.sup.2 on the coated front side and a Cobb.sub.60 value of 72 g/m.sup.2 on the back.

Example 2 (Comparative Example)

[0082] The treatment of the base paper with the fatty acid chloride was carried out analogously to experimental set-up 1, with the difference that the base paper was not dried and had a moisture content of 5.9%. The paper treated in this manner had a Cobb.sub.60 value of 20 g/m.sup.2 on the coated front side and a Cobb.sub.60 value of 86 g/m.sup.2 on the back.

[0083] Obviously, the higher moisture content in the base paper resulted in poorer penetration of the fatty acid chloride into the paper and hence in a poorer product quality.

Example 3

[0084] The treatment of the base paper with the fatty acid chloride was carried out analogously to experimental set-up 1, with the difference that the paper was pre-dried in an air circulation drying oven for 1 min at 105° C. The paper treated in this manner had a Cobb.sub.60 value of 18 g/m.sup.2 on the coated front side and a Cobb.sub.60 value of 18 g/m.sup.2 on the back.

Example 4

[0085] The base paper was coated in a single layer of 5 g/m.sup.2 with a 20% aqueous solution of polyvinyl alcohol (Mowiol 4-98, degree of hydrolysis >98%) on a coating table from the company Erichsen GmbH with doctor blade No. 2 and a coating speed of level 5 at 25° C. The paper obtained thereby was dried for 24 h at 105° C. The treatment of the coated base paper with the fatty acid chloride was carried out on the side coated with polyvinyl alcohol analogously to example 3. The paper treated in this manner had a Cobb.sub.60 value of 4 g/m.sup.2 on the coated front side and a Cobb.sub.60 value of 58 g/m.sup.2 on the back.

[0086] Obviously, coating the paper with polyvinyl alcohol leads to a surface reaction of the fatty acid chloride with the hydroxyl groups of the polyvinyl alcohol and thus to a lower penetration of the fatty acid chloride into the paper. This leads to a poorer Cobb.sub.60 value on the untreated back.

[0087] In summary, examples 1-4 prove that pre-drying the paper web significantly improves the result of hydrophobization, particularly on the untreated back.