WO2016151004A1

WO2016151004A1 - Paper containing synthetic fibres

Info

Publication number: WO2016151004A1
Application number: PCT/EP2016/056355
Authority: WO
Inventors: Henri Rosset
Original assignee: Arjowiggins Security
Priority date: 2015-03-23
Filing date: 2016-03-23
Publication date: 2016-09-29
Also published as: EP3274502A1; KR20170140209A; RU2698693C2; RU2017133219A; CN107667198A; BR112017020295A2; FR3034110A1; RU2017133219A3; CN107667198B; EP3274502B1; FR3034110B1; PH12017501734A1

Abstract

The present invention relates to a paper containing: - fibrillated synthetic fibres; and - a mixture of non-fibrillated synthetic fibres with different shape factors in cross section, notably a mixture of non-fibrillated synthetic fibres of circular cross section and of flattened cross section.

Description

PAPER COMPRISING SYNTHETIC FIBERS

The present invention relates to fibrous documents, including secure documents. The invention relates more particularly but not exclusively to a paper suitable for producing secure documents and to its manufacturing process.

"Secure document" means a security or valuable document, such as a means of payment, for example a bank note, a check, a bank card or a restaurant ticket, an identity document, such as an identity card, a visa, a passport, including the personal data page of a passport, an inlay or a driving license, a lottery ticket, a ticket or an entry ticket to cultural or sporting events.

In order to guard against attempts to falsify or counterfeit a secure document, it is known to add to a document substrate security elements, for example in the form of fibers, boards, films, knitted structures or security threads. The document substrate may itself be made of a material that is difficult to counterfeit, and is then referred to as a "safety substrate".

Since the lifespan of secure documents is generally critical, "very high durability" security substrates have been developed.

In the field of sheet security substrates, cellulosic substrates, so-called "composite" substrates, plastic substrates and so-called "hybrid" substrates are known.

Cellulosic substrates are fibrous substrates generally obtained by the papermaking process, also called wet process, from cellulosic fibers such as hardwood fibers, coniferous fibers, annuals, especially cotton, or their mixtures.

By "papermaking" or "wet process" is meant a common papermaking process, including in particular the following successive steps:

draining a fiber suspension that can be refined beforehand and optionally comprising fillers and additives conventionally used in paper milling and / or specific safety elements,

- pressing of the wet sheet obtained, then

drying. The so-called "composite" substrates are cellulosic substrates whose fibrous composition comprises, in addition to the cellulosic fibers, synthetic fibers. Such fibers are generally introduced at levels of less than 20% by dry weight relative to the total weight of the substrate, and their use makes it possible to increase the mechanical strength of the substrate.

The presence of cellulosic fibers plays an important role in the entanglement and fixation of synthetic fibers, which makes it possible to reveal the intrinsic potential of synthetic fibers. Indeed, in the development of the mechanical performance of a sheet material, the performance of the polymer of the synthetic fibers are important but the ability of interaction of the fibers between them is also critical. The presence of refined cellulosic fibers greatly favors the bridging between the cellulose and the polymer of the synthetic fibers.

Composite substrates have better resistance to circulation than cellulosic substrates. The expression "resistance to circulation" denotes the combination of the following properties: bending resistance, tear resistance and resistance to soiling.

The so-called "hybrid" substrates comprise at least one cellulosic or composite substrate associated with at least one plastic layer. With respect to the cellulosic or composite substrate that composes them, they generally exhibit equivalent tear resistance and improved bending resistance.

Hybrid substrates used in the field of security substrates are described in particular in applications WO 2006/066431, WO 2004/028825, EP 1 854 641, WO 03/054297 and WO 94/29105.

Plastic substrates are conventionally obtained by extrusion of a polymer. These substrates are normally of "very high durability".

Such plastic substrates are especially described in applications EP 2 225 102, WO 99/67093, WO 97/01438 and WO 83/00659. These substrates have good resistance to bending and soiling, but their resistance to tear initiation is relatively low.

Their security is also more difficult, insofar as these substrates are not compatible with the main safeties implemented for paper substrates (cellulosic, composite or hybrid) such as watering and insertion, at least partially by mass, security threads, for example as described in applications EP 0 059 056, GB 2 388 377 and GB 2 381 539.

There are also substrates called "non-woven". A nonwoven substrate is defined in ISO 9092 and EN 29092 as being a manufactured sheet, consisting of a directionally or randomly oriented fiber web or web, bonded by friction and / or cohesion, and / or adhesion , excluding paper and products obtained by weaving, knitting, tufting or seaming, incorporating binding yarn or filament or felts by wet embossing, whether or not needle punched.

The association of the nonwoven industry (or INDA) defines them as "a leaf or a veil of natural fibers and / or fibers or filaments manufactured, excluding paper, which have not been woven and which can be linked together in different ways. "

These substrates and their manufacture are described in more detail in the files "Nonwovens" (Gérard Coste, 25 June 2004) and "Material science & engineering 554 - Nonwovens science and technology II" (Larry C. Wadsworth, spring 2004 ) accessible on the Internet at the following addresses:

http://cerig.efpg.inpg.fr/tutoriel/non-tisse/sommaire.htm, and http://web.utk.edu/~mse/Textiles/index.html.

The nonwovens are described as being able to be used as safety substrates in the applications WO 2002/38368 and FR 2 447 995. These substrates generally consist of long non-cellulosic fibers, for example of length between 3 and 25 mm. , and have a high mass volume and porosity, which gives them a low resistance to soiling.

The nonwovens are manufactured according to various processes, especially in the dry process, for example by carding or aerodynamic process (also called "Airlaid"), in the melted process, especially by extrusion (also called "Spunbond") or extrusion blow molding (also called "Meltblown"), wet (also called "Wetlaid") according to a process similar to the paper process, or in other ways, including dissolution in a solvent (also called "Flash spinning").

Nonwovens made in the wet process generally comprise cellulosic fibers, for example at least 10%, especially in order to ensure better cohesion to the substrate obtained. Moreover, when the proportion of cellulosic fibers in the nonwovens made in the wet process is low or even zero, the hydrogen bonds formed between these fibers do not make it possible to ensure sufficient cohesion to the substrate and it is therefore necessary to at least one bonding step. Such a bond can be achieved by impregnation, spraying or coating of latex, by thermo-fixing, by needling or by water jet bonding (also called "Spunlace").

An example of a nonwoven substrate with little or no cellulosic fibers is described in EP 2 438 599.

The mechanical properties of a paper can also be improved by introducing into the mass of it reinforcing fibers. These reinforcing fibers are generally introduced at a rate of more than 3% by dry weight, relative to the total mass by dry weight of the paper fibers, and are most often based on synthetic polymers type polyamide 6.6 (PA 6.6) or polyethylene terephthalate (PET) for the mechanical strength that these polymers confer and for economic reasons, manufacturing and good interaction with the cellulosic fibers of the paper.

By "synthetic fibers", it is necessary to understand fibers made with one or more synthetic polymers, which are polymers obtained from a chemical synthesis, in particular by a polymerization reaction of monomers, coupled or not to a crosslinking reaction.

Preferably, the unsplit synthetic fibers have a number average length of between 0.5 and 8 mm, better 2 and 8 mm, and even more preferably 4 and 6.5 mm.

For information, the table below groups the orders of magnitude of the tear strength and the folding resistance of the substrates discussed above.

The tear strength is determined according to ISO 1974 "Paper - Determination of Tear Strength - Elmendorf Method" and bending strength according to ISO 5626 "Paper; determination of the folding resistance ". Substrates Substrates Substrates

Cellulose substrates

plastic hybrid composites

Resistance to

800 1100 800 250 tear (mN)

Resistance to

2500 5000> 5000> 50000 folding

In order to obtain novel substrates having improved strength properties, including improved tear resistance and bend strength, particularly tear strength greater than that of paper security substrates of the art prior and a folding resistance at least equivalent to that of plastic substrates, the Applicant has developed internally a paper, comprising:

synthetic fibers with fibers; and

unsplit synthetic fibers.

Such a paper is also compatible with the main security measures implemented for the papers, especially the watermarking and the insertion, at least partially in mass, of security threads.

The present inventors have found that synthetic fibers, although having a significant contribution to sheet formation and watermark rendering, have a limited contribution to improving strength properties.

The Applicant has also found that the unsfabricated synthetic fibers, although having a significant contribution in terms of improving the strength properties, have a negative influence on the hand (mass volume) of the paper and rendering the watermark.

There remains a need to further improve the mechanical strength properties, including tear strength and bending strength, without unduly harming sheet formation and rendering of the eventual watermark.

The invention aims to meet this need, and it achieves this through a paper, comprising:

- synthetic fiber, unshaped synthetic fibers of section having a first form factor, and

unshaped synthetic fibers of section having a second form factor, greater than the first.

The presence of unglazed synthetic fibers of different shape factors further improves the characteristics of the paper, as detailed below.

The two form factors differ preferably by a factor of at least two. The first form factor may be close to 1, which corresponds to fibers of substantially circular cross section. The second form factor may be greater than 2, more preferably 3, more preferably 5 or 10, which corresponds to fibers of flattened cross section, in particular substantially rectangular.

The substrate according to the invention is a paper, which means that it is obtained by papermaking, in particular according to an inclined table method, flat table and / or round shape. It is preferably a round shape process, for example to obtain a better definition of watermark or to incorporate, at least partially in mass, a security thread.

The techniques conventionally used to secure the papers can thus be used to secure the substrate according to the invention. In addition, the substrate according to the invention has improved properties compared with cellulosic papers, in particular an upper tear resistance.

Fibrillated synthetic fibers

Fibrillated fibers are fibers with fibrils, i.e., extensions that deviate from the body of the fiber. The fibrillated fibers may in particular be fibers in which at least one wall has been partially broken off, causing the partial release of fibrils.

Such fibers are branched by the fibrils, the section of which is much smaller than that of the fiber as a whole, which increases the interaction of these fibers with the other fibers, in particular synthetic fibers, and limits the ability of the fibers to slip the fibers. one against the other. Such fibers are described for example in documents FR1317778 and FR2199015.

The fibrillated fibers therefore play an important role in the cohesion of a paper according to the invention, in particular by entanglement effects. The paper according to the invention can comprise synthetic fibers which are fibers which are fibers of polyamide (PA), polyethylene (PE), polypropylene (PP), poly (ethylene terephthalate) (PET, also called polyester), polyvinyl alcohol (PVA), aromatic polyester (e.g., Vectran ^® sold by Kuraray), polyamide imide, polyolefin, and preferably polyacrylic fibers, for example such as those marketed by the company under the reference Sterling CFF 111-2. Preferably, the material of the synthesized fibers has a tensile strength of between 300 and 600 MPa.

The presence of the synthetic fibers frayed in the invention overcomes the absence or the lower amount of cellulosic fibers, and provides the desired mechanical performance in terms of resistance to tearing and bending.

According to a preferred variant of the invention, the paper comprises fibers made of polyethylene, especially high density polyethylene. Indeed, in addition to their ease of implementation, these fibers make it possible to obtain a good rendering of watermark. The proportion of fibrillated fibers of polyethylene is preferably greater than 50% by dry weight relative to the total dry weight of the fibers. The average length of the fibrillated fibers of polyethylene is preferably between 0.5 and 2 mm.

In particular, when the fibrous composition of the paper comprises at least 20%, preferably at least 50%, by dry weight of fibrillated fibers of polyethylene, it is also possible:

to create bonds by heat sealing, in particular to strengthen the paper,

to create translucent and / or raised patterns, in particular by embossing, compression and / or thermoforming, and / or

- To recycle the paper by melting at the melting temperature of the polyethylene, the other components of the paper generally having melting temperatures higher than the latter.

Preferably, the synthetic fibrilated fibers have an average length of between 0.5 mm and 8 mm, preferably between 2 mm and 8 mm and better still between 4 and 6.5 mm.

The specific surface area of the synthetic fibers which are screened according to the invention is preferably between 35 and 75 m ² / g, more preferably around 50 m ² / g. She is measured according to ISO 9277 "Determination of the mass area (specific surface area) of solids by gas adsorption - BET method".

Preferably, the paper according to the invention comprises more than 5% by dry weight, better still more than 10% by dry weight and more preferably more than 20% by dry weight, of synthetic fibers fibrillated with respect to the total weight of the paper. As a variant, the paper according to the invention comprises more than 50% by dry weight of fibrillated synthetic fibers relative to the total weight of the paper

The fibrillated synthetic fibers may be white or colored, in particular of a color that may be the same or different from that (s) of other synthetic fibers.

The level of fibrillation of the fibers may be between 5 and 700 ml and preferably between 5 and 100 ml according to the CSF standard.

The fibers may contain at least one tracer, said tracer for identifying the fibers by a specific means, in particular by exposure to UV and / or IR radiation and / or by exposure to a chemical developer. This tracer can thus be a luminescent tracer, especially fluorescent under UV or IR.

The fibrillated fibers may not all have the same formulation.

Non-fibrillated synthetic fibers having a first shape factor section, in particular with a substantially circular section

Preferably, the form factor of these fibers is less than 1.5, more preferably less than or equal to 1.3, more preferably 1.1, which corresponds to a substantially circular section.

The form factor is defined as the ratio of the largest external dimension in cross-section to the smallest external dimension in the same section. A fiber of perfectly circular section thus has a form factor equal to 1. An oval section fiber of low eccentricity may have a form factor close to 1. In the case of a rectangular section, the form factor is equal to ratio of the width of the section to its thickness. In the case of a square section, the form factor is equal to 2 ^1/2 .

The non-fibrillated synthetic fibers of first form factor, in particular of circular section, are preferably chosen from polyamide (PA), polyacrylic, polypropylene (PP) and poly (ethylene terephthalate) fibers (PET, also known as polyester), polyvinyl alcohol (PVA), aromatic polyester (e.g. Vectran marketed by Kuraray), polyamide imide, ethylene vinyl alcohol copolymer (EVOH), polyolefin and preferably polyethylene (PE).

These non-fibrillated synthetic fibers are more preferably polyamide fibers, among other thermoplastic fibers.

The paper according to the invention preferably comprises less than 95% by dry weight, better less than 90% by dry weight and more preferably less than 80% by dry weight of such non-fibrillated synthetic fibers of first form factor, in particular of circular section, relative to the total weight of the paper.

The dry weight amount of unsplit fibers of first form factor, based on the total weight of the paper, is preferably greater than or equal to 5%.

Preferably, the non-fibrillated synthetic fibers of first form factor have a number average length of between 3 and 6 mm, and a titer of between 0.3 and 1.7 dtex.

Preferably, the non-fibrillated synthetic fibers of first form factor have a titration of less than 2 dtex, better still less than 1 dtex, more preferably less than 0.5 dtex. The non-fibrillated synthetic fibers of first form factor are, for example, the fibers marketed under the reference mini Eslon by the company Woongjin, and are PET fibers of 0.3 dtex, or for example the fibers marketed under the reference EP023 by the Kuraray company, and are 0.33 dtex PET fibers. In particular, the non-fibrillated synthetic fibers of first form factor, in particular of circular section, may be polyvinylated 6.6 l, 7dTex 4mm fibers marketed by Rhodia or poly (ethylene terephthalate) fibers marketed by the company Kuraray under the reference EP023 5mm.

The non-fibrillated synthetic fibers of first form factor may have the same color as the spun fibers or a different color.

Non-fibrillated synthetic fibers of second form factor, in particular of flat section, in particular rectangular

These fibers are preferably fibers of "flattened" cross-section, that is to say synthetic fibers for which the section has a width greater than or equal to three times, preferably five times and more preferably 10 times, the thickness of this same section. Thus, the form factor of these fibers is preferably greater than or equal to 3, better still greater than or equal to 5, even more preferably greater than or equal to 10. The width of the section of the unshaped synthetic fibers with a second form factor section, in particular with a shape factor of at least 3, is preferably between 5 and 25 μιη, more preferably between 10 and 20 μιη.

The thickness of the section of the unshaped synthetic fibers of second form factor, in particular of form factor greater than or equal to 3, is preferably between 0.5 and 10 μιη, more preferably between 1 and 5 μιη.

Preferably, the non-flashed synthetic fibers of second form factor, especially of form factor greater than or equal to 3, are chosen from polyamide (PA), polyacrylic, polypropylene (PP) and poly (terephthalate) fibers. terephthalate) (PET, also referred to as polyester), polyvinyl alcohol (PVA), aromatic polyester (e.g., Vectran ^® sold by Kuraray) imide polyamide, ethylene vinyl alcohol copolymer (EVOH) of polyolefin and preferably polyethylene (PE).

The non-flashed synthetic fibers of second form factor, especially of form factor greater than or equal to 3, are more preferably polyamide and / or polyester fibers.

In particular, the non-flashed synthetic fibers of second form factor, especially of form factor greater than or equal to 3, may be mixed polyester and polyamide fibers marketed by Kuraray, for example under the reference Wramp W101, or polyester fibers sold by the company Teijin, for example under the reference TA 14N.

The paper according to the invention preferably comprises more than 10% by dry weight, better still more than 15% by dry weight and more preferably more than 25% by dry weight of unshaded synthetic fibers of second form factor, especially of factor of form greater than or equal to 3, relative to the total weight of the paper.

The paper according to the invention preferably comprises less than 60% by dry weight, better less than 50% by dry weight and more preferably less than 40% by dry weight of non-fibrillated synthetic fibers of second form factor, in particular of factor of form greater than or equal to 3, relative to the total weight of the paper.

Preferably, the non-flashed synthetic fibers of second form factor, especially of form factor greater than or equal to 3, have a length number average between 2 and 10 mm, preferably between 3 and 7 mm and more preferably between 5 and 6 mm, and a title between 0.2 and 3 dtex.

The unshaped synthetic fibers of second form factor, especially of form factor greater than or equal to 3, may have the same color as the unshaded fibers or a different color.

The non-flashed synthetic fibers of second form factor, in particular of form factor greater than or equal to 3, are preferably obtained from multi-component ("splittable fiber") primary fibers, preferably two-component fibers. These primary fibers may be in the form of segmented ribbon, segmented cross, or may have a multilobal section, in particular trilobal, or a segmented circular section, hollow or not hollow Examples of such fibers are shown in Figures 1 to 6 described below.

The two-component primary fibers 1 shown in these figures comprise a first component 2 and a second component 3. They are, for example, polyester and polyamide, respectively.

FIG. 1 represents a two-component primary fiber 1 with a section segmented into sectors, called a "pie wedge fiber" ("pie wedge fiber"). The sectors of one component alternate with those of the other component, around the axis of the fiber. The sectors separate in the pulp, during the manufacture of paper for example by stirring the fibrous suspension. In order to allow this separation (or cleavage), the sectors may be bonded together by a soluble glue. Such fibers are made by extrusion.

FIG. 2 represents a two-component primary fiber 1 with a so-called "segmented ribbon fiber" section.

FIG. 3 represents a two-component primary fiber 1 with a so-called "hollow pie wedge fiber" section.

FIG. 4 represents a two-component primary fiber 1 with a so-called "segmented cross fiber" section.

FIG. 5 represents a two-component primary fiber 1 with a so-called "tipped trilobal fiber" section. FIG. 6 represents a bicomponent primary fiber 1 with a multilayer section whose components alternate on one side of the section on the opposite side, called "conjugated"("conjugatedfiber" in English).

Preferably the components of such primary fibers separate during their implementation for the manufacture of a paper according to the invention, so as to obtain said non-screened fibers with a second form factor section, in particular flattened with a factor of form greater than or equal to 3.

The unsplit synthetic fibers with rectangular section are preferably obtained from two-component cross-section fibers.

Preferably, the non-flashed synthetic fibers of second form factor, especially of form factor greater than or equal to 3, have a titration of less than 3 dtex. The non-flashed synthetic fibers of second form factor, in particular of form factor greater than or equal to 3, are for example the fibers sold under the reference TA 14N by the company Teijin, and are polyester fibers, or come for example dissociation of the fibers sold under the name Wramp W101 by Kuraray, which are polyester / polyamide conjugated two-component fibers of 3.3 dtex before cleavage.

The multicomponent primary fibers, when they are dissociated, can produce only unsplit synthetic fibers with form factors of greater than or equal to 3. As a variant, they produce at the same time fibers with a shape factor of strictly less than 3, in particular 2, better at 1.1, and fibers of form factor strictly greater than 3. All of the unshaped synthetic fibers of the invention, whose shape factors are different, can come from the dissociation of the same type of primary fibers. In a variant, the mixture of unsplit synthetic fibers of different form factors, according to the invention, comes both from the introduction of fibers having a first form factor, in particular of circular section fibers, and multicomponent primary fibers. , in particular two-component.

Other fibers

The paper according to the invention may comprise less than 5% by dry weight of non-synthetic fibers, such as cellulosic fibers, relative to the total weight of the paper, and preferably less than 2% by dry weight of non-cellulosic fibers by report to the total weight of the paper, still better be free of non-synthetic fibers, such as cellulosic fibers.

In particular, in a preferred embodiment, the fibers of the paper according to the invention consist exclusively of synthetic fibers and non-glossy synthetic fibers.

treatments

It is possible to reinforce the cohesion of a paper according to the invention by introducing a polymeric binder such as polyvinyl alcohol (PVA) or a styrene-acrylic copolymer, which has a synergy with the synthetic fibers. , surprisingly allowing the development of the folding resistance and also of the tear resistance. The application of the polymeric binder may be by impregnation, surfacing or coating, preferably the polymeric binder being introduced at least partially by mass.

The composition may comprise an anionic polymeric dispersion, in particular flocculated. Preferably, the composition comprises at least 3% by dry weight of anionic polymeric dispersion, in particular flocculated. Such anionic polymeric dispersion improves the wet tensile strength, the cohesion and the folding resistance of the paper.

The latex used is, for example, the latex marketed by Dow Chemicals under the reference 94755.04 or a latex as described in the international application WO2008152299 or the application WO2014083527.

The formulation of the paper according to the invention may also comprise a main cationic flocculating agent, in an amount of between 1 and 5% by dry weight relative to the total weight of the paper, and optionally a secondary cationic flocculating agent, in an amount between 0.1 and 0.5% by dry weight, chosen from a cationic resin, polyacrylamides, polyethyleneimines, polyvinylamines and their mixtures, preferably a cationic resin, and better a polyamide-amine-epichloridin resin.

Other binders may be used, including a transparent or translucent elastomeric binder, such as a polyurethane and a colloidal silica, or an acrylic polymer binder or styrene-acrylic copolymer. In order to reinforce the strength of the paper, flocs (aggregates) of a polyurethane having a considerable elongation at break, for example greater than 600%, may be incorporated into the paper by anionic dispersion, especially in a proportion of between 5 and 45.degree. % by dry weight relative to the total weight of the paper.

Other constituents of paper

The paper according to the invention may comprise any adjuvants and compounds conventionally used in the manufacture of papermaking paper, such as fillers, retention agents, bonding agents and / or resistance agents in the state. wet, especially epichlorohydrin resins.

The paper according to the invention can in particular comprise filler-blocking filler, in particular plastic filler such as, for example, polyvinyl chloride (PVC) particles marketed by Kern One under the reference Lacovyl Pb 1302. Such fillers make it possible in particular to densify the paper according to the invention.

Paper manufacturing

The paper according to the invention can be manufactured according to the usual manufacturing techniques of cellulosic papers, except the steps specifically related to the presence of cellulosic fibers if they are absent. In particular, the refining step, which is particularly energy-consuming, can be advantageously suppressed.

The manufacturing method can be adapted to the presence of security elements such as a watermark or security thread.

The paper preferably has a hand less than or equal to 2.5 cm ³ / g, better a hand less than or equal to 2 cm ³ / g and more preferably less than or equal to 1.5 cm ³ / g.

The paper may have a thickness between 100 and 300 μιη, better between 100 and 150 μιη. It is measured according to ISO 534 "Paper and board - Determination of thickness, density and specific volume".

The basis weight of the paper may be between 70 g / m ² and 150 g / m ² and preferably between 90 g / m ² and 110 g / m ² . It is measured according to ISO 536 "Paper and board - Determination of grammage". Watermark

The paper according to the invention may comprise a watermark. This watermark can be formed on round shape or flat table.

The watermark may be of any known type, for example clear and / or dark, possibly multiton or multi-toned, for example as described in patent EP 1 122 360, EP 2 350 384 and EP 2 550 395.

Security thread

The paper according to the invention may comprise a security thread introduced in bulk or between two jets of paper according to the invention bonded in the wet phase. The security thread can be at least partially introduced into the paper.

The paper may comprise a fibrous ribbon, in particular a cellulosic fibrous ribbon as described in the application WO2008043965, a plastic ribbon or a knitted ribbon, especially as described in the application WO2006016088.

The wire may be metallized and / or holographic and / or interferential and / or provided with optical structures, including lenses or mirrors.

Multijet paper

The paper according to the invention can be single or multijet.

In the case of a multijet structure, the jets may or may not have the same fibrous composition. In particular, the paper may comprise firstly a jet of synthetic fibers according to the invention, and secondly a jet of cellulosic fibers, assembled in wet phase, the jet according to the invention then constituting a reinforcing jet.

As a variant, the paper may comprise, on the one hand, a jet of synthetic fibers, especially of the invention, whose fibrous composition promotes the formation of the sheet, especially the epair, and the rendering of the watermark, and other a synthetic fiber jet according to the invention whose fibrous composition promotes the mechanical strength properties, said jets being assembled in the wet phase.

The jets can be of the same color or not.

properties

The Bendsten porosity of the paper may be between 0 mL / min and 10,000 mL / min, better still between 1 mL / min and 7000 mL / min. It is measured according to ISO 5636-3 "Paper and cardboard; determination of air permeability (average value); Part 3: Bendtsen method » Preferably, the double fold folding resistance Schopper of the paper according to the invention is greater than 5000, more preferably greater than 20000, more preferably greater than 50000. It is measured according to ISO 5626 "Paper; determination of the folding resistance ".

Preferably, the tear strength of the paper (measured according to the standard

ISO 1974) is greater than 1000 mN, more preferably greater than 2000 mN, more preferably greater than 3000 mN. It is measured according to ISO 1974 "Paper - Determination of tear strength - Elmendorf method"

The invention makes it possible to obtain a synthetic paper whose mechanical properties, in particular the resistance to bending and tearing, are superior to those of a conventional paper, while at the same time allowing, if it is desired, to produce watermarks of quality and quality. satisfactory resolution.

The use of synthetic fibers, non-wettable and less sensitive to water than cellulosic fibers, provides a substrate with increased durability, including naturally more resistant to attack by mold.

Security elements and secure document

The paper according to the invention preferably comprises a security element, in particular a watermark or a security thread, for example a thread introduced into window (s), as mentioned above.

The invention also relates to a secure document comprising a paper according to the invention.

In a preferred embodiment of the invention, the secure document is a bank note. The secure document can also be another type of payment method such as a check or a restaurant ticket, an identity document such as an identity card, a visa, a passport, including the personal data page of a passport, a secure label, a heat-shrinkable secure sleeve, a "prelam" or "inlay" insert for a passport or card, in particular a smart card, or a driver's license, a lottery ticket, a ticket, a ticket entrance to cultural or sports events, a playing card or a card to collect. An insert is a layer supporting a contactless communication device, preferably radio frequency. The paper according to the invention and / or the secure document made with the paper according to the invention may comprise one or more additional security elements as defined below.

Among the additional security features, some are detectable to the eye, daylight or artificial light, without the use of a particular device. These security elements comprise for example colored fibers or boards. These security elements are called first level.

Other types of additional security elements are detectable only with a relatively simple apparatus, such as a lamp emitting in the ultraviolet (UV) or infrared (IR). These security elements comprise for example fibers, boards or particles. These security elements may be visible to the naked eye or not, being for example luminescent under a lighting of a Wood lamp emitting in a wavelength of 365 nm. These security elements are said to be second level.

Other types of additional security elements require for their detection a more sophisticated detection device. These security elements are for example capable of generating a specific signal when they are subjected, simultaneously or not, to one or more external excitation sources. The automatic detection of the signal makes it possible to authenticate, if necessary, the document. These security elements comprise, for example, tracers in the form of active materials, particles or fibers capable of generating a specific signal when these tracers are subjected to optronic, electrical, magnetic or electromagnetic excitation. These security elements are said to be third level.

The additional security element (s) present in the paper according to the invention or the secure document according to the invention may have first, second or third level security features.

In the case where the formulation of the synthetic fiber composition comprises fibers of a thermoplastic material, in particular of polyethylene, heat fusible, the additional safety element or elements can be fixed to the document by simple heating, thus avoiding the use of a hot-activatable adhesive. Comparative tests

Various comparative tests have been conducted in order to demonstrate the advantageous properties of a paper according to the invention.

In the following :

the tear resistance is measured according to the ISO 1974 standard,

the resistance to folding (or double fold called "Schopper folding") is measured according to the ISO 5626 standard,

- the grammage is measured according to ISO 536,

the thickness is measured according to the ISO 534 standard and makes it possible to obtain the hand (or mass volume) which is equal to the thickness divided by the grammage,

- The quality of the watermark is assessed visually by a score ranging from 1 (bad) to 6 (very good).

The raw substrates, that is to say without any treatment as defined above, and the substrates surfaced, that is to say, impregnated with a polyvinyl alcohol composition or a composition of styrene-acrylic copolymer are tested.

The properties of a substrate whose fibrous composition is composed only of synthetic fibers and non-glossy synthetic fibers circular section (Example 1) were compared to those of a substrate whose fibrous composition corresponds to that of the Example 1 except that a portion of the unshaped synthetic fibers of circular section is replaced by unsplit synthetic fibers of rectangular section (Example 2).

The results, shown in the table below, reflect the fact that the mixture of unshaped synthetic fibers of different sections and of different form factors, in this case circular and rectangular sections, makes it possible to increase the resistance to tearing and folding resistance without unduly degrading the quality of the watermark. Satisfactory properties are then obtained, in particular good tear strength. Example 1 Example 2

Fused polyethylene fibers SWP E400 66% 66%

Polyamide 6.6 fibers with non-circular cross-section

30% 10% fibrillated Rhodia 1.7 dtex half-mate 4 mm

Unshaded fibers with rectangular section

20% polyamide / polyester Wramp W101

Raw substrate

Weight g / m ² 88.2 85.5

Tear resistance mN 511 1518

Watermark Quality Note 3.0 2.8

Substrate surfaced

Weight g / m ² 105.7 115.9

Hand cm ³ / g 1.40 1.37

Tear resistance mN 1884 2005

Folding resistance number of plies 8033 23787

The proportions are mass.

The properties of a substrate whose fibrous composition is composed of glossy synthetic fibers and of unsplit synthetic fibers with a circular section (Example 3) were compared with those of a substrate whose fibrous composition corresponds to that of the example 3 apart from the fact that the unsecured synthetic fibers with circular section are completely replaced by unsplit synthetic fibers of rectangular section (Example 4).

The results, recorded in the table below, reflect the fact that the replacement in all of the unsecured synthetic fibers circular section by synthetic fibers unshaped rectangular section does not significantly increase the tear resistance and the folding resistance, and degrades the quality of the watermark. As demonstrated by the comparison of the examples, it is therefore the combination of unshaped synthetic fibers of different form factors, namely circular section fibers and rectangular section fibers in the examples considered, which makes it possible to increase the tear resistance and folding resistance without unduly degrading the quality of the watermark. Example 3 Example 4

Fibrillated Polyacrylic Fibers CFF 111-2 10% 10%

Fiber polyethylene fibers SWP E400 76% 76%

Polyamide 6.6 fibers with non-fibrillated circular section

10%

Rhodia 1.7 dtex half-mate 4 mm

Wramp polyamide / polyester rectangular section fibers

10%

W101

Raw substrate

Weight g / m ² 88.2 86.4

Resistance to tear mN 702 856

Watermark quality Note 6 4,5

Substrate surfaced

Weight g / m ² 92.8 96.6

Hand cm ³ / g 1.41 1.45

Tear resistance MN 1082 701 number of

Folding resistance 1387 254 double-ply

The proportions are mass.

Depending on the intended application, it may be important to obtain a dense and low porous substrate, allowing in particular the realization of a quality watermark.

The properties of a substrate whose fibrous composition is composed of 76% fibrilated synthetic fibers, non-fibrillated synthetic fibers with circular section and 10% non-fibrillated synthetic fibers with rectangular section (example

5) were compared:

- on the one hand to those of a substrate whose fibrous composition is composed of 56%> of fibrillated synthetic fibers, of unshaped synthetic fibers with circular section and of 30% of unshaped synthetic fibers with rectangular section (example

6), and

- on the other hand, to those of a substrate whose fibrous composition is composed of 56%> fibrillated synthetic fibers, non-glossy synthetic fibers with a circular section and 30%> a mixture of unshaped synthetic fibers. rectangular section (Example 5) (Example 7).

The results, recorded in the table below, reflect the fact that the fibrous compositions of Examples 6 and 7 make it possible to achieve, after surfacing, very high tear strength and bending resistance performances. We also note that the Wramp W101 fibers allow to obtain a better tear resistance than Teijin TA 14N fibers, which highlights the interest of using multicomponent primary fibers.

The proportions are mass.

The expression "having one" shall be understood as being synonymous with "having at least one", and "between" means included limits, unless otherwise specified.

Claims

1. Paper, comprising:

synthetic fibers that are frayed,

unsplit synthetic fibers with a first form factor section, and

unshaped synthetic fibers having a second form factor section, greater than the first.

2. The paper of claim 1, unsplit synthetic fibers of first form factor having a form factor less than or equal to 1.3 better than 1.1.

3. Paper according to claim 1 or 2, unsplit synthetic fibers of second form factor having a form factor greater than or equal to 3, more preferably 5, more preferably 10.

4. Paper according to any one of the preceding claims, the unsplit synthetic fibers of first form factor being fibers of circular section.

5. Paper according to any one of the preceding claims, the unsplit synthetic fibers of second form factor being flattened section fibers, better rectangular section.

A paper as claimed in any one of the preceding claims, the gap between the first and second form factors being greater than or equal to 3, more preferably 5, more preferably 10.

A paper according to any one of the preceding claims, the non-screened fibers of second form factor resulting from the dissociation of multicomponent primary fibers within the pulp used in the manufacture of paper, preferably two-component fibers, more preferably polyester / polyamide bicomponent fibers.

8. Paper according to claim 7, the multicomponent fibers being conjugated fibers, preferably polyester / polyamide fibers

9. Paper according to any one of the preceding claims, the mass quantity of non-screened synthetic fibers of second form factor being greater than that of the first form factor fibers.

The paper of any one of the preceding claims, including a security element.

11. Paper according to one of the preceding claims, comprising a watermark.

Paper according to any one of the preceding claims, wherein the unsplit synthetic fibers are selected from polyamide fibers, poly (ethylene terephthalate) fibers, polyvinyl alcohol fibers, copolymer fibers. ethylene vinyl alcohol and polyolefin fibers, preferably polyethylene.

Paper according to any one of the preceding claims, comprising more than 5% by dry weight, preferably more than 10% by dry weight, and more preferably more than 20% by dry weight, of unsplit synthetic fibers compared to to the total weight of the paper, the amount of unsplit synthetic fibers of second form factor, especially of form factor greater than or equal to 3, being greater than or equal to 10% by dry weight, relative to the total weight of the paper.

A paper as claimed in any one of the preceding claims, wherein the flashed synthetic fibers are polyethylene blended fibers.

Paper according to any one of the preceding claims, wherein the unsplit synthetic fibers have a number average length of between 0.5 mm and 8 mm, preferably between 2 mm and 8 mm and more preferably between 4 and 6,5mm.

16. Paper according to any one of the preceding claims, comprising less than 95% by dry weight, preferably less than 90% by dry weight, and more preferably less than 80% by dry weight, of synthetic fiber screened with respect to weight. total paper.

17. Paper according to any one of the preceding claims, comprising a surfacer, in particular being impregnated with a surfacing agent, the surfacing agent comprising or preferably consisting of polyvinyl alcohol.

18. Paper according to any one of the preceding claims, comprising a latex, in particular flocculated.

19. Paper according to the preceding claim, comprising at least 3% by dry weight of latex, in particular flocculated, relative to the total weight of the paper.

The paper according to any one of the preceding claims comprising less than 5% by dry weight of non-synthetic fibers, such as cellulosic fibers, relative to the total weight of the paper, preferably less than 2% by dry weight relative to the total weight of the paper, more preferably being free of non-synthetic fibers, such as cellulosic fibers.

21. Paper according to any one of the preceding claims, the fibers of the paper being exclusively constituted by fimbriated synthetic fibers and unsplit synthetic fibers.

22. Paper according to any one of the preceding claims, having a hand less than or equal to 2.5 cm ³ / g, better still less than or equal to 2 cm ³ / g.

23. Paper according to any one of the preceding claims, having a basis weight of between 70 g / m ² and 150 g / m ² and preferably between 90 g / m ² and

110 g / m ² .

24. Paper according to any one of the preceding claims, having a double-fold fold resistance Schopper greater than or equal to 5000, preferably greater than or equal to 10000, more preferably greater than or equal to 25000.

25. Paper according to any one of the preceding claims, having a tear resistance measured according to the ISO 1974 standard of greater than 1000 mN, better still greater than 2000 mN, and preferably greater than 3000 mN.

26. Paper according to any one of the preceding claims, comprising a security thread, in particular at least partially introduced into the paper.

27. Secure document comprising a paper as defined in any one of the preceding claims.

28. Secure document according to the preceding claim, constituting a means of payment such as a bank note, a check or a restaurant ticket, an identity document such as an identity card, a visa, a passport, a passport, secure label, a heat-shrinkable safety sleeve, a passport or card insert, in particular a smart card, or a driver's license, a lottery ticket, a ticket, a ticket to cultural or sports events, a ticket card to play or a card to collect.