Process for obtaining a cloth with high performances for digital printing and relative cloth

Abstract

A process for preparing cloth for bookbinding with gloss or matte finish, in cotton or viscose, suitable for digital printing, includes: A) preparing an unfinished cloth for bookbinding by desizing, washing, treating with optical white, sizing and drying; B) pretreating the cloth by applying, on at least one of the two sides, at least one composition closing pores of the cloth to make the surface planar; C) on the side intended for printing, applying by coating a layer of a paste having a viscosity of at least 7500 cps, and drying this layer; the paste being the mixture of at least one aqueous composition containing a 35% (dry) acrylic resin and components that at temperatures of around 200° C. for less than one minute initiate the state of polymerization, and of at least one nonionic thickener; and D) calendering at ambient temperature the cloth obtained from step C).

Claims

1. A process for preparing a fabric in natural, artificial or synthetic fibre, including natural and/or artificial fibre, with gloss/bright or matt finish, said process comprising the steps of A) preparing an unfinished fabric or a cloth for bookbinding by desizing, washing, treating with optical whitener, sizing and drying; B) closing the pores of a surface of said cloth/fabric by pre-treating the fabric or the cloth obtained from step A) by applying, on at least one of the two sides, at least one composition in the form of a first paste so as to close the pores of the treated at least one of the two sides of the fabric or of the cloth to make the surface of the treated at least one of the two sides of the fabric or of the cloth planar; C) on the side of said fabric or cloth intended to be printed, applying by coating a layer of a second paste having a viscosity of at least 7500 cps, and drying the layer to obtain a layer receptive to the liquid ink of digital printers; said viscosity being measured at the ambient working temperature when the paste is applied, generally between 10° C. and 30° C., said second paste being a mixture consisting of at least one nonionic thickener, and at least one aqueous composition containing about 35% by weight, relative to the second paste, as dry weight of an acrylic resin and components that at temperatures around 200° C. for less than one minute initiate the state of polymerization/vulcanization, the components being an initiator, a crosslinking agent, a vulcanization agent, or a crosslinking accelerator, and optional additives; said second paste not containing colorant for fibres and inorganic/organic pigment such as for example calcium carbonate, clay, zeolite, silica; and D) calendering at ambient temperature the cloth obtained from step C), wherein said fabric is suitable for being printed directly by digital printing.

2. The process according to claim 1, wherein the cloth for bookbinding is a Panama cotton (100%), with a plain weave and having a weave repeat of 26/12 threads per cm.sup.2.

3. The process according to claim 1, wherein the cloth for bookbinding is made in viscose (100%) with a plain weave and having a weave repeat of 29.5/23.5 threads per cm.sup.2.

4. The process according to claim 1, wherein the application of the paste of step B) takes place by coating.

5. The process according to claim 1, wherein the step B) and/or C) takes place by air knife coating apt to regulate the thickness of the applied layer.

6. The process according to claim 1, wherein in the case of cotton cloth/fabric with a gloss/bright finish (BHPI), the step B) takes place by coating only the reverse side of the cloth, using a paste having a total dry matter content of approximately 23% by weight and a viscosity of approximately 50000 cps at between 10° C. and 30° C., said paste containing combinations of acrylic resins, kaolin and vinyl resin, in addition to a filler.

7. The process according to claim 1, wherein in the case of cotton cloth/fabric with a matt finish (MattHPI), the step B) takes place by coating both the reverse and obverse sides of the cloth, using a paste used for passport cloths containing about 23% by weight of dry matter and comprising hydroxyethyl propyl cellulose, acrylic resin, kaolin, vinyl resin.

8. The process according to claim 7, wherein before the step C), the obverse side of said cotton cloth/fabric with a matt finish obtained from step B) is then subjected (third phase) to the application of a primer for offset printing, comprising a composition of about 38% by weight of dry matter and having a viscosity of 6000 cps.

9. The process according to claim 1, wherein, in the case of viscose or cotton cloth/fabric with bright gloss finish, after step C) and before passing to the calendering step D), said cloths/fabrics are bonded with paper in a laminating machine.

10. The process according to claim 2, wherein the application of the paste of step B) takes place by coating.

11. The process according to claim 3, wherein the application of the paste of step B) takes place by coating.

12. The process according to claim 2, wherein the step B) and/or C) takes place by air knife coating apt to regulate the thickness of the applied layer.

13. The process according to claim 3, wherein the step B) and/or C) takes place by air knife coating apt to regulate the thickness of the applied layer.

14. The process according to claim 4, wherein the step B) and/or C) takes place by air knife coating apt to regulate the thickness of the applied layer.

15. The process according to claim 2, wherein in the case of cotton cloth/fabric with a gloss/bright finish (BHPI), the step B) takes place by coating only the reverse side of the cloth, using a paste having a total dry matter content of approximately 23% by weight and a viscosity of approximately 50000 cps at between 10° C. and 30° C., said paste containing combinations of acrylic resins, kaolin and vinyl resin, in addition to a filler.

16. The process according to claim 3, wherein in the case of cotton cloth/fabric with a gloss/bright finish (BHPI), the step B) takes place by coating only the reverse side of the cloth, using a paste having a total dry matter content of approximately 23% by weight and a viscosity of approximately 50000 cps at between 10° C. and 30° C., said paste containing combinations of acrylic resins, kaolin and vinyl resin, in addition to a filler.

17. The process according to claim 4, wherein in the case of cotton cloth/fabric with a gloss/bright finish (BHPI), the step B) takes place by coating only the reverse side of the cloth, using a paste having a total dry matter content of approximately 23% by weight and a viscosity of approximately 50000 cps at between 10° C. and 30° C., said paste containing combinations of acrylic resins, kaolin and vinyl resin, in addition to a filler.

18. The process according to claim 5, wherein in the case of cotton cloth/fabric with a gloss/bright finish (BHPI), the step B) takes place by coating only the reverse side of the cloth, using a paste having a total dry matter content of approximately 23% by weight and a viscosity of approximately 50000 cps at between 10° C. and 30° C., said paste containing combinations of acrylic resins, kaolin and vinyl resin, in addition to a filler.

Description

(1) Further features of the invention will be made clearer by the following detailed description, referred to one of its purely non-limiting examples, illustrated in the accompanying drawings in which:

(2) FIG. 1 is a schematic drawing of a line of coating of a cloth for bookbinding.

(3) The plant of the coating line, which is a phase provided by the present process, was denoted in FIG. 1 overall with the reference numeral 100, wherein the production sequence goes from right to left starting from the top right.

(4) Said plant 100 is formed by a series of units, each one having its own specific function, starting with an unrolling unit 1, also defined as unwinder assembly, which has the purpose of unwinding the roll of unfinished cloth for bookbinding 2, in cotton or viscose, which has already been subjected to the initial step A) of preparation.

(5) The unfinished cloth 2 is made to pass in a series of rollers 3 which also have the purpose of tensioning the cloth 2 in view of the coating section 10.

(6) The coating section 10 is composed of at least one scraper 4 with relative container for the pouring of one of the pastes indicated above for the pores closure of step B) or of actual coating of step C).

(7) Below said scraper 4 a cooler cylinder 5 is placed, designed to cool the coated cloth, and optionally a further cooler cylinder 6.

(8) There is preferably present a second scraper 4′ and relative cooling roller 5′ in order to increase the quantity of product applied to the cloth and at the same time avoid surface irregularities.

(9) Subsequently the cloth coated on the surface with the paste of chosen composition is made to pass on a conveyor belt 7 formed by a pin chain 8 designed to restrain the coated cloth against the belt 7, avoiding movements of the cloth during its transport which could crack the layer of product applied previously.

(10) Above said pin chain 8 one or more side brushes 9 are moreover provided, designed to restrain the sides of the coated cloth against the conveyor belt, avoiding possible transverse movements of the coated cloth.

(11) The conveyor belt 7 has the purpose of transferring the coated cloth inside a drying oven 30 necessary for the drying of the finishing layer applied. Said drying oven 30 can reach high temperatures, also around 200° C., and can also be used to dry, if necessary, the pastes for the covering of the holes of step B).

(12) At the exit of the conveyor belt 7 there is present an extractor roller 11 designed to tension the coated cloth in order to send it to the subsequent transport rollers assembly 12 which also provides a cooler roller 13.

(13) At the exit of this transport rollers assembly 12 the following are provided in sequence: a cutter assembly 14 designed to cut the selvedge so as to finish the sides of the coated cloth, a metres counter assembly 15, a humidity reading head 16 for measuring the humidity of the coated cloth, a winder assembly 17 for winding into a roll the coated cloth ready to be subjected to an optional subsequent treatment of coating B) and/or C).

(14) It should be noted that this plant of the coating line 100 is used preferably for every phase of coating provided in the steps B) and/or C) of the present process, even if this is not binding for the purpose of the present invention so that the same number of coating units as the number of coating steps provided by the present process could be provided.

(15) The present invention is not limited to the particular embodiments described previously and illustrated in the accompanying drawings, but instead numerous detail changes may be made thereto within the reach of the person skilled in the art, without thereby departing from the scope of the same invention, as defined in the appended claims.