EP0322287B1 - Wet-laid sheet for use as a coating support - Google Patents

Description

The invention relates to a sheet prepared by papermaking and usable as a substitute for products known under the name of impregnated glass veils.

• des fibres cellulosiques,
• des fibres non cellulosiques,
• au moins une poudre thermoplastique,
• au moins un liant,
• éventuellement des charges.

We have already proposed substitutes for these glass veils. Patent application FR-A-2 461 061 by the applicant describes products obtained by forming a sheet on a paper machine with a flat or round canvas, from an aqueous composition, by removing water from the sheet thus formed on the canvas and drying it. The aqueous composition comprises:

• cellulosic fibers,
• non-cellulosic fibers,
• at least one thermoplastic powder,
• at least one binder,
• possibly charges.

The flocculant is for example a cationic agent which confers positive charges on the cellulosic fiber. According to patent application EP-A-0 006 390 of the applicant, the flocculating agent is added in two stages and allows improved retention of the thermoplastic powders and fillers.

Patent application EP-A-0 039 292 of the applicant describes a sheet material obtained on a paper machine, from an aqueous composition comprising reinforcing fibers which are not cellulosic, a thermoplastic resin powder, a polyolefin paste, a binder and at least one flocculating agent. This material is intended to be used in hot forming processes, involving a fusion of the thermoplastic powder and the polyolefin paste. This material is hot-consolidated; before the thermoplastic powder and the polyolefin paste melt, these mechanical characteristics are insufficient for it to be used as it is and in particular as a coating support.

Patent application FR-A-2 530 274 by the applicant describes a paper sheet, the dimensional stability of which is improved by adjusting the quantity of glass fibers. In this publication, provision is made for coating or impregnating the paper sheet thus obtained, with an aqueous composition containing in particular a plasticizer, thermoplastic powders and an emulsifier. The layer is then heat treated to cause partial gelation of the thermoplastic powders. The user of such a paper sheet thus impregnated, then deposits the various compositions of thermoplastic material to obtain a coating, for example a floor covering or wall covering.

Such paper sheets must have excellent physical characteristics.

The sheets must withstand passage through industrial ovens up to high temperatures, in particular during the manufacture of these floor or wall coverings. The support paper sheets must therefore be heat resistant.

It has been sought, moreover, for floor coverings to obtain covering support sheets which have good tensile-delamination resistance (R.T.D.). Indeed, if this parameter is not correct, the sheet may delaminate in its thickness during this use.

Finally, for this same use of floor covering, it is necessary to obtain particularly dimensionally stable products.

For economic reasons, attempts have been made to obtain leaves that are as sparse as possible.

• une R.T.D. satisfaisante, supérieure à 300 N/m, plus préférentiellement 500 N/m et au-delà,
• une épaisseur suffisante, supérieure à 350 micromètres et préférentiellement supérieure à 450 micromètres et voire 500 micromètres,
• une forte main,
• une stabilité dimensionnelle à l'humidité élevée.

The invention aims to solve these problems. The object of the invention is therefore to obtain a sheet by the papermaking route, which can be used as a coating support for manufacturing floor or wall coverings and which has the following physical properties:

• a satisfactory RTD, greater than 300 N / m, more preferably 500 N / m and beyond,
• a sufficient thickness, greater than 350 micrometers and preferably greater than 450 micrometers and even 500 micrometers,
• a strong hand,
• dimensional stability at high humidity.

Finally, for reasons of manufacturing imperatives, we seek with these properties sufficient rigidity and simultaneously, a hot resistance of the sheet because it is intended to be coated with a plastic material and then subjected to heat.

As regards dimensional stability to humidity, the level necessary to obtain a stable product after laying, that is to say without rolling and without curling, depends on the thickness and / or grammage of the sheet. Thus, for a thick product, in thicknesses of 400 micrometers or more, an elongation of 0.25% in the cross direction seems to be a limit not to be exceeded.

However, those skilled in the art know that these imperatives are often incompatible with each other. Thus, those skilled in the art anticipate that if the thickness of the sheet increases, its tensile-delamination resistance decreases. It is easy to understand that a thick cardboard delaminates more easily than a thin cardboard. We call, in fact, cardboard, any paper sheet which has a significant grammage, namely more than 200 g / m2.

However, surprisingly and completely unpredictably, the Applicant has found that the particle size of the thermoplastic powder has an influence on the R.T.D. and that by using powders with a large particle size compared to the powders usually used in stationery (maximum particle size: 5 micrometers), the R.T.D. while increasing the thickness of the sheet.

The invention therefore relates to a new sheet prepared by the papermaking process, having a tensile-delamination resistance. greater than 300 N / m, usable as a coating support, comprising cellulose fibers, non-cellulose fibers, at least one flocculant, at least one thermoplastic powder, at least one binder, optionally fillers and additives, said sheet optionally coated on at least one side with an impregnation layer comprising at least one plasticizer of the thermoplastic powder.

According to the invention, thermoplastic powders are used whose average particle size is between 25 and 60 micrometers. Preferably, P.V.C. powders obtained by suspension polymerization can be used, the average particle size of which is between 25 and 60 micrometers. More preferably, it is possible to use P.V.C. powders obtained by suspension polymerization, the average particle size of which is between 25 and 50 micrometers.

Finally, the property of heat traction and the rigidity are improved when an aqueous composition of plasticizer is used as coating or impregnating sauce in mixture with an emulsifier and with a starch, modified or not.

• a) On fabrique selon une première étape une feuille papetiére à partir d'une composition aqueuse comprenant le mélange de base suivant : (les quantités sont données en poids de produits secs).
  
  
  
  Le mélange est dilué dans les circuits de tête de la machine à papier à la concentration nécessaire pour l'obtention du grammage souhaité.
  On introduit par ailleurs, juste avant la caisse de tête, en continu :
  
  
  On obtient, après passage sur la toile d'une machine à papier Foudrinier, enlèvement de l'eau et séchage de manière traditionnelle, des feuilles dont le grammage est d'au moins 220 g/m2.
• b) On effectue ensuite une imprégnation de la feuille obtenue par une composition de revêtement ou "sauce de couchage" à l'aide d'une size press. La sauce de couchage peut être appliquée, soit sur une face de la feuille soit sur les deux faces. Dans le cas du traitement sur une seule face, l'imprégnation est faite, de préférence, sur la face destinée à recevoir les couches de revêtement visibles après la pose. Cette imprégnation peut être réalisée soit sur machine à papier industrielle, soit sur size-press de laboratoire.

The following description will make it possible to understand, using a first series of examples, how the invention can be put into practice.

• a) A paper sheet is produced according to a first step from an aqueous composition comprising the following basic mixture: (the quantities are given by weight of dry products).
  
  
  
  The mixture is diluted in the head circuits of the paper machine to the concentration necessary to obtain the desired grammage.
  We also introduce, just before the headbox, continuously:
  
  
  After passing over the canvas of a Foudrinier paper machine, removal of the water and drying in the traditional manner, sheets whose grammage is at least 220 g / m2.
• b) An impregnation of the sheet obtained is then carried out with a coating composition or "coating sauce" using a size press. The coating sauce can be applied either on one side of the sheet or on both sides. In the case of treatment on one side, the impregnation is preferably done on the side intended to receive the visible layers of coating after installation. This impregnation can be carried out either on an industrial paper machine or on a laboratory size press.

Another embodiment of the invention can be made according to the procedure described above, but the mass composition is as follows (the quantities are given by weight of dry products):

The laboratory tests E 14.12.87 and E 15.12.87 and the industrial test E 2137 correspond to the first mass composition. The coating sauce, the composition of which is given in Table I, is applied to only one side of the sheet.

The industrial test E 2145 corresponds to the second mass composition. The coating sauce, the composition of which is given in Table I, is applied to both sides of the sheet.

The results for these four tests are presented in Table I.

The hot tensile strength is measured as follows: an Adamel-Lhomargy DY 22 device is used, with a 10 daN load cell, a recorder and an Adamel-Lhomargy CE 02 heating chamber.

Place the two jaws inside the heating box, raise the temperature to the selected value (200 ° C), quickly introduce (5 seconds) the paper test piece (140 mm x 15 mm) between the two jaws separated by 100 mm, the sample is left for 2 minutes at temperature, before breaking according to standard ISO 1924/1976. Finally, we average five measurements.

The tensile-delamination resistance is measured as follows:

1) Principle

• 1.1. A coating is carried out on both sides of the paper with a PVC in the form of plastisol, the composition of which is chosen to represent the type of plastisol most commonly used in Europe. She understands :
  
• 1.2. We make the gelation then the expansion
• 1.3. The delamination force is evaluated using a conventional device.

2) Method

• 2.1. Coating and gelation
  • paper cut to dimensions 16 cm x 20 cm (or more).
  • PVC coating 450 g / m2 with a blade.
  • PVC gelation 2 min. at 160 ° C.
• 2.2. Expansion
  • The PVC-coated sample is kept on both sides in a ventilated oven.
  • The treatment time is adjusted to 200 ° C. to obtain regular foaming, approximately 2 min.
  • Cool 5 min.
  • Two strips 50 cm wide and 20 to 25 cm long are cut.
• 2.3. Delamination
  • The internal delamination is induced in the paper, manually, at the two ends of the sample.
  • The sample is placed between the two jaws of a traction device.
  • The sample is kept horizontal when the device is operated. Speed: 10 cm / min.
  • The traction force curve is recorded. The average value of this curve gives the tensile-delamination resistance (RTD).
    This resistance is expressed in cN / cm. The hand expressed in cm3 / g is obtained by dividing the thickness of the sheet by its grammage.

Table I therefore shows that it is possible to produce a sheet by the papermaking route, usable as a coating support and having all the physical properties targeted by the invention.

Limits of the particle size range of the powdered thermoplastic resin.

Various tests have been carried out with poly (vinyl chloride) of average particle size between 2 and 80 micrometers.

The basic composition of the sheet and the composition of the coating sauce are those of test E 15.12.87. The coating sauce is applied to both sides of the sheet. The removal is 70 g / m2.

These various tests are listed in Table II.

Figure 1 shows the evolution of the hand and the R.T.D. depending on the grain size.

In view of the poor results (FIG. 1) observed with the powders of particle size usually used in stationery (particle size of approximately 1 to 5 micrometers) and subsequent tests made with powders of average particle size of 20 micrometers, the skilled person in the art would have concluded that powders with an average particle size of more than 10 micrometers cannot be used to achieve the physical objectives set. He would therefore not have sought to go beyond it.

On the contrary, the plaintiff has overcome this unfavorable prejudice and has continued testing. She found, to her surprise, that by using even coarser powders (average particle size greater than or equal to 25 micrometers), it was possible to find interesting physical characteristics, in particular with regard to R.T.D. and the hand (see Figure 1). The increase in hand with the particle size of the powder is also an economic advantage for such products which are sold by the thickness.

However, the upper limit of the average particle size of the thermoplastic powder is imposed by the powdering of the sheet. Such dusting would cause fouling of the paper machine and also of the material during the operations of coating the thermoplastic layers at the transformers.

In practice, the Applicant has observed dusting for an average particle size greater than 60 micrometers.

According to the invention, the average particle size of the thermoplastic powder must therefore be between 25 and 60 micrometers and preferably between 25 and 50 micrometers.

Table II shows the particle size of the powders according to the polymerization method.

Type of powdered thermoplastic resin

The previous examples show that the invention can be carried out with a homopolymer of vinyl chloride as a thermoplastic powder.

However, the nature of the thermoplastic powder should not be limited to the PVC homopolymer. Indeed, it is obvious that any polymer developing, after melting, plasticization or gelation, a high binding power may be suitable, in particular vinyl chloride / vinyl acetate; vinyl chloride / vinyl acetate / ethylene terpolymers.

May also be suitable for plasticized P.V.C. powders. These powders can come from recycled P.V.C. obtained by grinding already plasticized P.V.C., which was in the form of films, sheets or tubes manufactured according to different processing techniques.

These pre-laminated P.V.C. powders can also come from mixtures called "wetblends" or "dryblends".

• a) on réalise préalablement le mélange (wetblend) suivant :
  
• b) Puis, en laboratoire sur formette, on fabrique une feuille papetière comme mentionné précédemment, mais la poudre thermoplastique est remplacée par le mélange contenant le PVC préplastifié (wetblend). Dans cet exemple on n'a pas mis de charge minérale.

The use of a "wetblend" for carrying out the invention can be done as follows (the quantities are given by weight of dry products):

• a) the following mixture (wetblend) is produced beforehand:
  
• b) Then, in the laboratory on a formette, a paper sheet is manufactured as mentioned above, but the thermoplastic powder is replaced by the mixture containing the preplasticized PVC (wetblend). In this example we did not put a mineral filler.

The physical characteristics of the sheet thus obtained are as follows (Table III)

These results show that a PVC powder preplasticized and having a particle size in the range required according to the invention can be suitable for manufacturing a sheet by papermaking according to the invention.

Nature of the plasticizer

Di (2-ethylhexyl) phthalate can be used as plasticizer and also dibutyl phthalate, benzyl butyl phthalate, dihexyl phthalate, diisononyl phthalate, tricresylphosphate or any other plasticizer, usually for the transformation of poly (vinyl chloride).

The following examples presented in Table 4 illustrate the use of di (2-ethylhexyl) phthalate or D.O.P. benzyl butyl phthalate or B.B.P. dibutyl phthalate or D.B.P.

The samples are produced according to the procedure described for the tests in Table I.

For each sample, the composition of the mass is as follows (the quantities are expressed by weight of dry products):

The composition of the coating sauce applied to the sheet in size-press is as follows (the quantities are expressed by weight of dry products):

Nature of cellulosic fibers and degree of refinement

According to the invention, any cellulosic fiber or mixtures of these fibers can be used.

For example, we could use:
Softwood pulp treated with soda and bleached
Softwood pulp treated with soda and semi-bleached
Softwood pulp treated with soda and unbleached
Softwood pulp treated with bisulfite and bleached
Softwood pulp treated with bisulfite and unbleached
Hardwood pulp treated with soda and bleached
Hardwood pulp treated with soda and semi-bleached
Unbleached mechanical pulp
Bleached mechanical pulp
Bleached straw chemical pulp
Bleached alfa chemical paste
Since, for the intended applications, a good level of dimensional stability is sought according to the invention, it is preferable to use cellulosic fibers which are slightly refined in particular between 15 and 35 ° SR.

Nature of non-cellulosic fibers

Non-cellulosic fibers are mineral or organic fibers.

• Fibres de polyéthylène (de préférence 0,8 à 1 mm de longueur)
• Fibres de verre (de préférence 5 à 15 µm de diamètre et 3 à 6 mm de longueur)
• Fibres de sulfate de calcium ou gypse aciculaire (de préférence de 0,5 à 3 mm de longueur)
• Fibres de polyester (de préférence de 3 à 6 mm de longueur)
• Fibres liantes telles que les fibres d'alcool polyvinylique
• Fibres de polypropylène (de préférence 0,8 à 1 mm de longueur)
• Laine de roche (0,1 à 0,3 mm de longueur).
• Fibres de polyamide

On pourra également utiliser des mélanges de ces fibres.
Leur rôle principal est d'apporter la stabilité dimensionnelle au support par rapport à l'eau et aux variations de température, ces deux propriétés étant nécessaires pour les applications envisagées.For example, we could use:

• Polyethylene fibers (preferably 0.8 to 1 mm in length)
• Glass fibers (preferably 5 to 15 µm in diameter and 3 to 6 mm in length)
• Calcium sulfate fibers or needle gypsum (preferably 0.5 to 3 mm in length)
• Polyester fibers (preferably 3 to 6 mm in length)
• Binding fibers such as polyvinyl alcohol fibers
• Polypropylene fibers (preferably 0.8 to 1 mm in length)
• Rock wool (0.1 to 0.3 mm in length).
• Polyamide fibers

Mixtures of these fibers can also be used.
Their main role is to provide dimensional stability to the support with respect to water and to temperature variations, these two properties being necessary for the applications envisaged.

It is preferable to use cut glass fibers, with a diameter between 7 and 12 micrometers and a length between 3 and 6 mm.

Nature of flocculant

The flocculants which can be used are for example the following:
Aluminum sulphate
Aluminum polychloride (aluminum hydroxychloride)
Sodium and calcium aluminate
Mixture of polyacrylic acid and polyacrylamide
Polyethyleneimine
Copolymer of acrylamide and β-methacrylyloxyethyltrimethylammonium methyl sulfate
Polyamine-epichlorohydrin and diamine-propylmethylamine resin
Polyamine-epichlorohydrin resin
Polyamide-polyamine-epichlorohydrin resin
Cationic polyamide-polyamine resin
Condensation products of aromatic sulfonic acids with formaldehyde
Sodium pretreated epoxy polyamino amide
Aluminum acetate
Aluminum form
Mixture of aluminum acetate, sulfate and formate
Aluminum chloride (AlCl₃)
Cationic starch

Nature of the mineral filler

Optionally, add charges. The usable loads are for example the following:
Talc: Complex magnesium silicate - Particles from 1 to 50 micrometers, preferably 2 to 50 micrometers -. Specific weight from 2.7 to 2.8.
Kaolin: Aluminum silicate hydrate complex - particles from 1 to 50 micrometers, preferably 2 to 50 micrometers - specific weight 2.58.
Natural calcium carbonate: particles from 1.5 to 50 micrometers, preferably 1.8 to 30 micrometers - specific weight: 2.7.
Above-mentioned calcium carbonate: particles of 1.5 to 20 micrometers, preferably 2 to 20 micrometers - specific weight: 2.7.
Natural barium sulphate: particles from 2 to 50 micrometers specific gravity about 4.4 - 4.5.
Precipitated barium sulphate: particles 2 to 20 micrometers specific gravity about 4.35.
Diatomic silica: particles from 2 to 50 micrometers - specific gravity about 2 to 2.3.
Satin white: calcium sulfoaluminate hydrates.
Natural calcium sulphate: particles from 2 to 50 micrometers specific gravity about 2.32 to 2.96.
Hydrated alumina: particles from 2 to 50 micrometers.
Sodium and calcium aluminate: particles from 1 to 20 micrometers - specific weight 2.2.
Sodium silicoaluminate: particles from 1 to 20 micrometers specific gravity about 2.12.
Rutile titanium: particles from 0.5 to 10 micrometers - specific gravity about 4.2.
Titanium anatase: particles from 0.5 to 10 micrometers - specific gravity around 3.9.
Magnesium hydroxide: particles from 2 to 50 micrometers.
Alumina hydroxide: particles from 2 to 50 micrometers.
Note : the specific weight is expressed in g / ml.
Preferably, calcium carbonate will be used which gives the sheet better heat resistance.

Nature of the binder

• Amidon natif, notamment amidon de maïs
• Amidon oxydé
• Amidon enzymé
• Carboxyméthylcellulose
• Copolymère contenant des motifs acryliques et des motifs d'acrylonitrile (latex)
• Polymère contenant des motifs acrylate d'éthyle, acrylonitrile,N-méthylolacrylamide et d'acrylate de butyle (latex)
• Polymère comportant des motifs de styrène et de butadiène (latex)
• Polymère comportant des motifs de styrène et de butadiène et des groupements carboxylés (latex)
• Poly(chlorure de vinyle) (latex)
• Poly(acétate de vinyle) (latex)
• Terpolymère acétate de vinyle/chlorure de vinyle/éthylène (latex)

On choisira de préférence les latex à motifs vinyliques ou acryliques, en particulier le terpolymère acétate de vinyl/chlorure de vinyle/éthylène.The binders which can be used according to the invention are for example the following:

• Native starch, especially corn starch
• Oxidized starch
• Enzyme starch
• Carboxymethylcellulose
• Copolymer containing acrylic units and acrylonitrile (latex) units
• Polymer containing ethyl acrylate, acrylonitrile, N-methylolacrylamide and butyl acrylate (latex) units
• Polymer comprising styrene and butadiene (latex) patterns
• Polymer comprising styrene and butadiene units and carboxyl groups (latex)
• Poly (vinyl chloride) (latex)
• Poly (vinyl acetate) (latex)
• Vinyl acetate / vinyl chloride / ethylene (latex) terpolymer

The latexes with vinyl or acrylic units will preferably be chosen, in particular the vinyl acetate / vinyl chloride / ethylene terpolymer.

Additives

It is optionally possible to use, in a conventional manner, the adjuvants known in the paper industry such as anti-foaming agents, agents for dry resistance, wet resistance, rot-proofing, antioxidants, dyes, flame retardants, etc. Polyvinyl chloride thermal stabilizers commonly used and which are miscible in plasticizers or water are suitable; preferably used barium and zinc salts.

The sheets obtained by the papermaking process according to the invention are characterized by their basic composition which comprises:

• 5 to 30% by dry weight of cellulosic fibers and preferably 12 to 25%,
• 1 to 16% by dry weight of cellulosic fibers and preferably 6 to 12%,
• 35 to 75% by dry weight of thermoplastic resin in powder form, and preferably 45 to 65%; the average particle size being between 25 and 60 micrometers and preferably between 25 and 50 micrometers.
• 0 to 40% by dry weight of mineral fillers and preferably 0 to 25% and more particularly, 5 to 16%,
• 0.1 to 30% by dry weight of at least one binder and preferably 4 to 10%,
• 0.1 to 3% by dry weight of at least one first flocculant and 0.1 to 0.6% of at least one second flocculant added just before the headbox, these two flocculants may be the same.

The level of flocculants will be adapted by a person skilled in the art; it depends on the quantity of materials introduced and in particular on the level of binder. The percentage of the second flocculant is given relative to the dry weight of the mass arriving in the headbox. The total of the above percentages, except the percentage of the second flocculant, must be equal to 100.

• 10 à 100 parts de plastifiant pour 100 parts de résine (ici la poudre thermoplastique), et de préférence 20 à 60 parts, et plus particulièrement 35 à 50 parts.

The coating composition or "coating sauce" which can optionally be applied to the sheet in size press, is characterized by the following formula:

• 10 to 100 parts of plasticizer for 100 parts of resin (here the thermoplastic powder), and preferably 20 to 60 parts, and more particularly 35 to 50 parts.

• 0,1 à 4 parts de stabilisant thermique de la poudre thermoplastique.
• 0 à 10 parts d'émulsifiant, le taux étant adapté par l'homme du métier.
• un liant dont le taux est adapté par l'homme du métier selon la dépose de la sauce souhaitée sur la feuille.
• éventuellement, une charge minérale.

(The level of plasticizer must be sufficient to carry out a complete plasticization of the thermoplastic powder introduced in mass).

• 0.1 to 4 parts of thermal stabilizer of the thermoplastic powder.
• 0 to 10 parts of emulsifier, the rate being adapted by a person skilled in the art.
• a binder, the rate of which is adapted by a person skilled in the art according to the deposit of the desired sauce on the sheet.
• possibly a mineral filler.

The following four examples were carried out by varying the thermoplastic powder / filler ratio (Table V).

The composition of the mass is as follows:

The composition of the "coating sauce" is that of test 15.12.87

The grammage of the paper sheet obtained according to the invention depends on the thickness and on the mass composition, in particular on the particle size of the powders used and on the possible deposition of the "coating sauce"; in all cases, it is greater than 200 g / m2 for a thickness of 500 micrometers.

Claims (13)

1. Sheet prepared by a papermaking process having a tension-delamination strength higher than 300 N/m, usable as covering base, comprising:

   - cellulose fibers;

   - non-cellulose fibers;

   - at least one flocculant;

   - at least one thermoplastic powder;

   - at least one binder;

   - optionally fillers,

   - optionally additives;

   said sheet being optionally coated on at least one face with an impregnating layer comprising at least one plasticizer for the thermoplastic powder, characterized by the fact that the thermoplastic powder has an average grain size comprised between 25 µm and 60 µm.
2. Sheet according to claim 1, characterized by the fact that it is formed by a papermaking process using an aqueous composition whose mass comprises the following dry matter percentages by weight:

   - 5% to 30% cellulose fibers refined to between 15°SR and 35°SR;

   - 1% to 16% non-cellulose fibers;

   - 35% to 75% thermoplastic resin in the form of a powder whose average grain size is comprised between 25µm and 60µm;

   - 0.1% to 30% of at least one binder;

   - 0.1% to 10% of at least one flocculant;

   - optionally 0% to 40% of at least one inorganic filler; with the total of the above components making 100%;

   - 0.1% to 0.6% of at least one second flocculant added immediately before the head box, the percentage being expressed relative to the dry weight of the mass.
3. Sheet according to one of claims 1 and 2, characterized by the fact that the thermoplastic powder has an average grain size comprised between 25µm and 50µm.
4. Sheet according to one of claims 1 to 3, characterized by the fact that the non-cellulose fibers are glass fibers.
5. Sheet according to one of claims 1 to 4, characterized by the fact the thermoplastic powder is selected from a polymer having a high content of vinyl chloride.
6. Sheet according to one of claims 3 and 5, characterized by the fact that the polymer having a high content of vinyl chloride is a polyvinyl chloride which is optionally preplastified and optionally recycled, a copolymer of vinyl chloride and vinyl acetate, a terpolymer of vinyl chloride, vinyl acetate, and ethylene.
7. Sheet according to one of claims 3, 5 and 6, characterized by the fact that the thermoplastic powder is selected from a poly(vinyl chlorides) prepared by polymerization in suspension and having an average grain size comprised between 25µm and 50µm.
8. Sheet according to one of claims 1 to 7, characterized by the fact that the optional impregnation layer comprises:

   - at least one plasticizer for the thermoplastic powder

   - at least one stabilizer for the thermoplastic powder

   - optionally at least one emulsifier

   - optionally at least one binder

   - optionally at least one inorganic filler.
9. Sheet according to one of claims 1 to 8, characterized by the fact that the composition of the optional impregnation layer comprises, per 100 parts of thermoplastic powder:

   - 10 parts to 100 parts of at least one plasticizer;

   - 0.1 part to 4 parts of at least one stabilizer for the thermoplastic powder,

   - optionally 0 part to 10 parts of at least one emulsifier.
10. Sheet according to one of claims 1 to 9, characterized by the fact that the plasticizer is selected from the phthalates of di(2-ethylhexyl), dibutyl, benzyl butyl, dihexyl, and diisononyl or the tricresylphosphate.
11. Sheet according to one of claims 8 to 10, characterized by the fact the binder is selected from starch, modified starch, or oxidized starch.
12. Sheet according to one of claims 1, 2, 8 to 11, characterized by the fact that it is made by a papermaking process using an aqueous composition comprising the following dry matter percentages by weight:

    A)

    - 12% to 25% cellulose fibers refined to between 15°SR and 35°SR;

    - 6% to 12% non-cellulose fibers;

    - 45% to 65% thermoplastic resin in the form of a powder having an average grain size comprised between 25µm to 60µm;

    - 4% to 10% of at least one binder;

    - 0.1% to 10% of at least one flocculant

    - optionally 0% to 25% of at least one inorganic filler; with the total of the above percentages being 100%;

    B)

    - 0.1% to 0.6% of at least one second flocculant, with this percentage being expressed relative to the dry weight of composition A).
13. Sheet according to one of claims 1 to 12, characterized by the fact that the composition of the optional impregnation layer comprises per 100 parts of thermoplastic resin:

    - 20 to 60 parts of at least one plasticizer;

    - 0.1 to 4 parts of at least one stabilizer for the thermoplastic powder

    - optionally 0 to 10 parts of at least one emulsifier.

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