FIBRE-BASED SUPPORT CONTAINING A LAYER OF A FUNCTIONALIZED WATERSOLUBLE POLYMER, METHOD OF PRODUCTION AND USE THEREOF

Abstract

A cellulose and/or synthetic fibre-based support of which at least one surface is coated with a layer containing at least one water-soluble polymer comprising hydroxyl or primary-secondary amino functional groups, at least some of which have been functionalized beforehand with at least one organic compound comprising at least one epoxy functional group, and at least one R.sup.1 group wherein R.sup.1 is a vinyl functional group or at least one Si(R.sup.2).sub.3 functional group and wherein R.sup.2=hydrogen atom, hydroxyl, alkoxy, alkyl, and combinations thereof.

Claims

1. A coated cellulose and/or synthetic fibre-based support, wherein the coated fibre-based support comprises: a cellulose and/or synthetic fiber-based support sheet, and a coating layer on at least one surface of the support sheet, wherein the coating layer comprises at least one water-soluble polymer comprising hydroxyl or primary-secondary amino functional groups, wherein at least some of the hydroxyl or primary-secondary amino functional groups on the polymer have been functionalized with at least one organic compound before the polymer is coated onto the at least one surface of the support, and wherein the at least one organic compound contains: (i) at least one epoxy functional group, and (ii) at least one R.sup.1 group wherein R.sup.1 is a vinyl functional group or at least one Si(R.sup.2).sub.3 functional group, where R.sup.2 is a group selected from the group consisting of hydrogen, hydroxyl, alkoxy, alkyl, and combinations thereof, wherein the at least one organic compound is grafted onto the water-soluble polymer via the at least one epoxy functional group by an alkylation reaction.

2. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the cellulose and/or synthetic fibre-based support sheet is a cellulose support sheet.

3. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the water-soluble polymer having hydroxyl functional groups is selected from the group consisting of starch, carboxymethyl cellulose (CMC), alginate, chitosan, pectine, chitin, glycogen, arabinoxylane, poly(vinyl alcohol), and hydrolysed or partially hydrolysed copolymers of vinyl acetate.

4. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the water-soluble polymer having hydroxyl functional groups is starch.

5. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the water-soluble polymer having primary-secondary amino functional groups is selected from the group consisting of polyethyleneimine; polyallylamine; chitosan; polyacrylamide; partially or totally hydrolyzed polyacrylamide; partially or totally hydrolyzed polyvinylamine and polyamines based on amino-ethyl-piperazine.

6. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the organic molecule corresponds to a molecule according to the formula H.sub.2C—O—CH—(R)—CH═CH.sub.2 or H.sub.2C—O—CH—(R)—Si—(R.sup.2).sub.3, wherein R is a linear, branched and/or cyclic carbon chain or a polydimethylsiloxane chain that may contain heteroatoms, and R.sup.2 is selected from the group consisting of hydrogen, hydroxyl, alkoxy, alkyl and combinations thereof.

7. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the organic molecule is a molecule selected from the group consisting of 2-vinyloxirane, 1,2-epoxy-4-pentene 1,2-epoxy-5-hexene, 1,2-epoxy-6-heptene, 1,2-epoxy-7-octene, 1,2-epoxy-8-nonene, 1,2-epoxy-9-decene, 1,2-epoxy-10-undecene, 1-allyloxy-2,3-epoxypropane, 1-allyloxy-3,4-epoxybutane, 1-allyloxy-2,3-epoxypentane, 1-allyloxy-2,3-epoxyhexane, 1-allyloxy-2,3-epoxyheptane, 1-allyloxy-2,3-epoxyoctane, 1-allyloxy-2,3-epoxynonane, 1-allyloxy-2,3-epoxydecane, 1-allyloxy-2,3-epoxyundecane, glycidoxypropyl trimethoxysilane, glycidoxypropyl triethoxysilane, and glycidoxypropyl trisiloxane.

8. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the organic molecule is present in an amount between 0.1 and 20% by weight of the water-soluble polymer.

9. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the functionalized water-soluble polymer is present in an amount of at least 1% by weight of the layer coated onto the fibre-based support.

10. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the layer coated onto the fibre-based support is present in an amount of 0.2 to 20 g/m.sup.2.

11. The coated cellulose and/or synthetic fibre-based support as recited in claim 1, wherein the fibres have a weight ranging from 30 to 160 g/m.sup.2.

12. A coated cellulose and/or synthetic fibre-based support produced by a method which comprises the steps of: (a) forming a cellulose and/or synthetic fibre-based support sheet with or without a parchementizing process; (b) functionalizing at least one water-soluble polymer comprising hydroxyl or primary-secondary amino functional groups by grafting at least one organic molecule comprising at least one epoxy group and at least one R.sup.1 functional group onto the water-soluble polymer, wherein R.sup.1 is a vinyl group or at least one —Si(R.sup.2).sub.3 functional group, where R.sup.2 is selected from the group consisting of hydrogen, hydroxyl, alkoxy, alkyl, and combinations thereof; (c) coating the cellulose and/or synthetic fibre-based support sheet obtained according to step (a) with a layer comprising the at least one functionalized water-soluble polymer obtained according to step (b) to obtain the coated cellulose and/or synthetic fibre-based support; and (d) optionally calendering or supercalendering the coated cellulose and/or synthetic fibre-based support.

Description

EXEMPLARY EMBODIMENTS OF THE INVENTION

[0096] The invention itself and the advantages that it offers will be explained in greater detail in the following description of exemplary embodiments and with reference to the following figures.

[0097] FIG. 1 represents the alkylation reaction, in an aqueous medium at a basic or acid pH, between a water soluble polymer containing hydroxyl functionalities and an organic molecule comprising both an epoxy function and a functional group among, for instance, Si—H, Si—OH, or vinyl. In this particular case, starch is the water soluble polymer containing hydroxyl functionalities while the molecule having an epoxy functionality refers to the general formula: H.sub.2C—O—CH—(R)—R.sup.1.

[0098] FIG. 2 represents the alkylation reaction, in an aqueous medium at a basic or acid pH, between a water soluble polymer containing primary and/or secondary amino functionalities and an organic molecule comprising both an epoxy function and a functional group among, for instance, Si—H, Si—OH, or vinyl. In this particular case, polyethyleneimine is the water soluble polymer containing primary and secondary amino functionality while the molecule having an epoxy functionality refers to the general formula: H.sub.2C—O—CH—(R)—R.sup.1.

EXAMPLES

Method for Preparing the Glassine According to the Invention:

[0099] A sheet consisting of 100% cellulose fibres is prepared by methods known to one skilled in the art. The support used in the examples is the commercial product Silca Classic Yellow 59 g/m.sup.2 (from Ahlstrom); for the production of the samples described in the examples, the support has not been coated with the standard formulation but with the formulations reported in the examples 1 and 2. In the case of the standard paper, the commercial grade Silca Classic Yellow has been used as such.

[0100] Off-line from the industrial machine, the water soluble polymer containing primary-secondary amino or hydroxyl functionalities is functionalized with an organic molecule by using the methods of examples 1 and 2. After the functionalization reaction, the polymer solution can be mixed with other products commonly used in this application (for example: clays, pigments, latexes, polymers and/or additives), diluted with water to the desired solid content and sent to the industrial machine for the coating step.

[0101] The mixture containing the functionalized water soluble polymer is then applied to a surface of the support by coating (1 g/m.sup.2), preferably by metering-size-press.

[0102] The support is then dried, remoisturized, and super-calendered.

Example 1

Functionalization Reaction of a Water Soluble Polymer Containing Primary and/or Secondary Amino Functionalities and Preparation of the Coating Recipe

[0103] In the present example, polyethyleneimine is the polymer containing primary and/or secondary amino functionalities since it contains both functionalities on the same polymer structure.

[0104] The commercial polyethyleneimine Polymin P (from Base is delivered as a water solution with a solid content of 50% w/w. In order to decrease the viscosity of the solution, Polymin P is diluted with water at a solid content of 20%. For the grafting reaction, an amount of 2% w/w of pure 1,2-epoxy-9-decene (from Sigma-Aldrich), compared to the weight of dry Polymin P, is slowly added to the polymer solution under vigorous stirring. The organic molecule 1,2-epoxy-9-decene is a liquid which is not soluble in water, so a vortex is required to create an emulsion of 1,2-epoxy-9-decene in the polymer solution, forming a cloudy solution. Due to the fact that Polymin Pin solution already has a pH between 11 and 13, the addition of a base in order to increase the pH to catalyze the reaction is not required. The solution is heated to 90° C. and maintained at this temperature under stirring for one hour. Subsequently, the pH of the solution is neutralized by addition of a water solution of sulphuric acid. Afterwards, 20% w/w of CMC and 5% w/w of glyoxal compared to the weight of Polymin P are added to the solution. The solution is then diluted with water to a final solid content of 8% w/w. Finally, the solution is transferred to the coating apparatus for the coating step. CMC is added in the coating formulation as a viscosity modifier to improve the film forming properties and the water retention of the coating formulation. Glyoxal is added as a cross-linking agent for the coating formulation.

Example 2

Functionalization Reaction of a Water Soluble Polymer Containing Hydroxyl Functionalities and Preparation of the Coating Recipe

[0105] In the present example, PVA, Celvol 20/99 (Celanese), is the representative polymer containing hydroxyl functionalities. Celvol 20/99 is delivered as a powder. A dispersion of PVA is produced in water by vigorous stirring. It is then heated up to 95° C. in order to completely dissolve PVA in water. A clear solution with a solid content of 12% is obtained. A solution of sodium hydroxide is added to the PVA solution in order to reach a pH value between 11 and 13. For the grafting reaction, an amount of 2.5% w/w of pure 1,2-epoxy-9-decene (from Sigma-Aldrich), compared to the weight of dry Polymin P, is slowly added to the polymer solution under vigorous stirring. The organic molecule 1,2-epoxy-9-decene is a liquid which is not soluble in water, so a vortex is required to create an emulsion of 1,2-epoxy-9-decene in the polymer solution, forming a cloudy solution. The solution is heated to 90° C. and maintained at this temperature under stirring condition for three hours. Subsequently, the pH of the solution is neutralized by addition of a water solution of sulphuric acid. Afterwards, 10% w/w of CMC and 5% w/w of glyoxal compared to the weight of PVA are added to solution. The solution is then diluted with water to afford a final solid content of 8% w/w. Finally, the solution is transferred to the coating apparatus for the coating step.

Example 3

Silicone Anchorage of Low Temperature Curing (LTC) Silicone Systems

[0106] Standard glassine (STD) and the glassine produced by the methods reported in examples 1 (EX1) and 2 (EX2) have been siliconized with LTC silicones. The silicone anchorage results have been compared. In order to assess the silicone anchorage, a standard test called rub-off test has been performed; this test is an abrasion test in which a sample of siliconized paper, pressed under a weight, is dragged on an abrasive textile. The silicone layer at the surface of the sample can be removed by the rubbing. By measuring the amount of silicone onto the samples before and after the rub-off test, it is possible to obtain a percentage of silicone that remains on the samples. The rub-off percentage 0% indicates that all the silicone has been removed from the sample, very poor adhesion; the rub-off percentage 100% indicates that all the silicone remained on the sample, the adhesion is ideal. For the release application, the rub-off value of 75% is commonly considered as the bottom limit for silicone anchorage. The following silicone formulation has been used in this example:

[0107] LTC silicone formulation bath:

[0108] Polymer: D920 (from Wacker)—18.07 g

[0109] Cross-linking agent: XV 525 (from Wacker)—1.43 g

[0110] Catalyst: C05 (i.e.: Platinum based from Wacker)—2.14 g

[0111] Deposit: 0.9 g/m.sup.2

[0112] Cross-linking for 30 seconds at 80° C. in a ventilated drying kiln

[0113] Table 1 shows that STD has a rub-off value of 18% (very poor adhesion of the silicone), whereas EX1 and EX2 have respectively rub-off values of 96% and 97% (both samples have very good adhesion properties for LTC silicone systems). So, in the case of standard glassine the LTC silicone cannot be used due to the poor adhesion of the silicone system to the substrate; on the contrary, LTC silicone systems can be used on glassine produced by the methods reported in the present invention.

TABLE-US-00001 TABLE 1 Sample STD EX1 EX2 Rub-off value 18% 96% 97%

Example 4

Silicone Anchorage Dependence on the Amount of Catalyst (i.e.: Platinum) in the Silicone Formulation

[0114] For thermal cured silicone systems used in release industry, the catalyst used is an organometallic compound of platinum. Due to the high price of platinum, there is a strong interest in reducing its amount in the silicone formulation. The first problem observed when a reduced amount of catalyst is used is a poor anchorage of the silicone to the substrate. Standard glassine (STD) and the glassine produced by the methods reported in examples 1 (EX1) and 2 (EX2) have been siliconized with a standard silicone formulation by using two different amounts of catalyst in the silicone formulation, and the silicone anchorage on different substrates has been tested. In order to evaluate the silicone anchorage, the rub-off test (described in example 3) has been performed. For the tests the following silicone formulations have been used:

[0115] Standard silicone formulation bath:

[0116] Polymer: 11367 (from Bluestar)—50 g

[0117] Cross-linking agent: 12031 (from Bluestar)—2.9 g

[0118] Catalyst (60 ppm Platinum): 12070 (from Bluestar)—1.56 g; or (30 ppm Platinum): 12070-0.78 g

[0119] Deposit: 0.9 g/m.sup.2

[0120] Cross-linking for 10 seconds at 160° C. in ventilated drying kiln

[0121] As it is possible to observe in table 2, an satisfactory rate of silicone anchorage is obtained for all samples when the silicone formulation contains 60 ppm of platinum. On the contrary, when the amount of platinum is decreased to 30 ppm, the silicone anchorage of samples EX1 and EX2 remains very good but the anchorage of STD is poor.

TABLE-US-00002 TABLE 2 STD EX1 EX2 Rub-off 90% 95% 98% (60 ppm of Platinum) Rub-off 54% 91% 93% (30 ppm of Platinum)