Paper sheet, process for preparing same and applications thereof particularly as product for substituting impregnated glass webs

Abstract

The invention relates to a paper sheet obtained essentially from (parts by dry weight)______________________________________ Fibers (cellulosic and 20 to 40"basic mixture" non-cellulosic) Fillers 80 to 60 Latex 40 to 105______________________________________in particular by a process of double flocculation, which has a very high resistance to delamination. The invention is applicable to floor and wall coverings.

Description

The present invention relates to the field of products for substituting impregnated glass webs.

More precisely, the invention relates to products in sheet form obtained by paper-making methods, with a high content of latex precipitated in the mass.

Applicants' French Patent Applications Nos. 82 13391 and 82 18624 (corresponding to U.S. patent application Ser. No. 513,432 filed on July 13, 1983), disclose paper sheets with a very high latex content, which may be used as products for substituting impregnated glass webs.

The products described in these Applications are characterized by a very high level of tear strength, both cold and hot.

Moreover, it is very difficult, after for example double-face coating of plasticol (PVC power+plasticizer) followed by a heat treatment at about 160.degree.-200.degree. C., to delaminate the composite product obtained.

Moreover, the product obtained presents a good aptitude to pliability.

These products do not contain fillers, but may contain up to 2/3 by weight of latex.

Furthermore, the man skilled in the art knows that the incorporation of fillers in a product of the type in question considerably reduces the mechanical properties and particularly the resistance to delamination.

As this latter property is essential for the application envisaged (product for substituting impregnated glass webs in applications to floor or wall coverings), this prior knowledge explains the absence of fillers in the formulae described in the above-mentioned Applications.

This prejudice is confirmed by certain simple comparative tests showing that any attempt to incorporate fillers is highly detrimental, particularly to the resistance to delamination.

In this respect, Tables I and II hereinafter show the comparison of typical formulations of the above-mentioned Patent Applications and the same formulations to which attempts have been made to add fillers.

Table I shows the formulations and Table II the results.

The following conclusions, which correspond to the prior knowledge of the man skilled in the art, are drawn from Table II:

The addition of filler leads to a substantial drop in the resistance to delamination.

Moreover, the considerable loss of bulk caused by the addition of this filler largely cancels the economic advantage of this filled composition, for a product which is sold as a function of width.

It has been discovered according to the invention that a certain domain of compositions of fibers, fillers and latex made it possible to obtain products which contain a high percentage of fillers (therefore very economical) but, and this is surprizing, which presents a resistance to delamination at least equal to that of the prior art products.

According to the invention, different compositions have been tested and enable the following limits to be established (parts by dry weight):

______________________________________"basic mixture" fibers (cellulosic or not) 20 to 40("BM") fillers 80 to 60[basic mixture: 100 parts] Latex 40 to 105______________________________________

These limits may fluctuate by reason of the nature of the ingredients of which the product is composed and of the grammage of the products. The variations of these parameters will depend in particular on the application and use of the product both by the manufacturers and by the customers. Mention will be made for example of the necessity to avoid blistering of the layers of polyvinyl chloride deposited by coating, or the necessity of not affecting the mechanical properties.

On reading the present specification and the embodiments, the man skilled in the art will be able to adapt the teaching of the invention to each particular case.

The non-cellulosic fibers will preferably be glass fibers, or other inorganic or synthetic fibers such as rock wool, polyester fibers and like fibers. Their main role is to provide dimensional stability for the support with respect to water and variations in temperature, these two properties being indispensable for the applications envisaged.

Being given that for the applications envisaged the invention seeks a high level of dimensional stability, it is preferable to use cellulosic fibers which have been weakly refined, particularly between 15.degree. and 35.degree. S.R.

In the tests, cellulosic fibers refined to 20.degree. S.R. and glass fibers with a length of about 3 to 4 mm and of 10-11 .mu.m diameter have been used.

However, glass fibers may be used whose length is between 3 and 12 mm, preferably 3 and 6 mm, and with a diameter of between 5 and 15 .mu.m.

A ratio of about 40 to 60 parts by dry weight of inorganic fibers for 100 parts of cellulose fibers will preferably be chosen, particularly when these inorganic fibers are glass fibers whose length is between 4 and 6 mm.

It may be advantageous, in order to increase the formation of the sheet, to use a mixture containing short inorganic fibers. In that case, to obtain the required stability, it will be necessary to increase the quantity of inorganic fibers with respect to the cellulosic fibers. In particular, when these short inorganic fibers are glass fibers of length less than 4 mm, a mixture containing 40 to 90 parts by weight of glass fibers for 100 parts by weight of cellulosic fibers will preferably be chosen.

The man skilled in the art knows that certain chemical treatments of the cellulosic fibers of the support make it possible to improve the dimensional stability (cf. EP Pat. No. 0 018 961 to ROCKWOOL, U.S. Pat. No. 4 291 101 to NIPPON OILS AND FATS or the article in "Papier, Cartons, Films, complexes" of June 1979, page 16, col. 2, para. 2).

Applying such chemical treatments on the support, the man skilled in the art may in particular reduce the quantities of glass fibers necessary for dimensional stability.

A ratio of about 40 to 60 parts by dry weight of inorganic fibers for 100 parts of cellulose fibers will preferably be chosen.

Moreover, to facilitate passage in the wet part of the paper-making machine, it is possible, if necessary (particularly for the compositions with a low content of cellulose or low grammage), to add reinforcing fibers in order to increase the wet mechanical strength. To this end, fibers of polyvinyl alcohol or polyolefins may be used for example in proportions known to the man skilled in the art and corresponding to the desired purpose. Depending on the content of these reinforcing fibers, it is possible to reduce the cellulose content.

The tests made on a large number of latices have shown that vinyl copolymers suited the best.

Suitable results were also obtained with styrene-butadiene copolymers and polymers or copolymers comprising acrylic structural units.

The best results were obtained with the following terpolymer latex (% by weight):

vinylacetate: 54-60 ethylene: 10-16 vinyl chloride: 27-33

The quantity of latex to be introduced in mass depends on the nature of the filler used in the formulation.

The flocculants may be selected from the products of which the list is given in the Patent Applications mentioned above (cf. Table III hereinafter).

Additives known in the paper-making field may also be used in conventional manner: antifoam agents, dyes, sizing, dry, wet resistance, anti-rot agents, etc.

The nature of the flocculants, their dose, as well as the number of places of introduction may vary as a function of the nature of the latex used, of the equipment, of the time of contact between the products; the total dose of the flocculants, which itself depends on the nature of these flocculants (in particular on the molecular weight, ionicity, etc.), will preferably be between 2 and 20 parts by dry weight, for 100 parts by weight of dry latex.

On this subject, the following Tables and the modus operandi hereinafter provide the indications which will enable the man skilled in the art to adapt the technique according to the invention to a variation of these parameters.

The mode of operation corresponding to the tests set forth in Table IV is as follows (additions in that order):

______________________________________fibrous mixture:cellulosic fibers of conifers, parts by weight (dry)treated with sodium hydroxide,bleached 20.degree. S.R.glass fibers (4.5 mm, 10 .mu.m; parts by weight (dry)"VETROTEX"fillers parts by weight (dry)flocculant (polyamine/polyamide- parts by weight (dry)epichlorohydrin)[Nadavin LT][contact time of about 5 mins.]latex (cf. Table IV) parts by weight[contact time of about 5 mins.]flocculant added after the latex(polyacrylamide of highmolecular weight)in two steps (cf. Table I): (cf. (1) in the chest x.sub.1 parts by weight (dry)Table I) (2) at the head x.sub.2 parts by weight (dry)______________________________________ x.sub.1 is the quantity necessary for total precipitation. The mixture is then sufficiently stable to be conducted up to the head part of the machine where the last addition of flocculant is effected; x.sub.2 is the percentage by dry weight with respect to the total dry composition.

The compositions used as well as the results of the tests are given in Tables IV or XV hereinafter: of course, these examples have no limiting character.

By a first series of examples, it was sought to show the influence of certain parameters on the physical characteristics of the sheet which are interesting for competing with the impregnated glass web.

It has been observed (Tables VI and VII) that the nature of the inorganic filler used considerably influences the interesting physical characteristics and, in particular, the resistance to delamination of the paper coated on 2 faces.

Thanks to the choice of the filler, it may moreover be envisaged to reduce the quantity of latex introduced in mass without substantially affecting the resistance to delamination of the paper coated on two faces and the dimensional stability (Tables VIII and IX).

The tests show that calcium carbonate is to be used in preference to the other inorganic fillers.

Aluminum hydroxide which gives satisfactory results will suit for manufacturing fire-proof supports.

Other tests (Tables X to XIII; Tables VIII and IX: MP 19454 and 19456) demonstrate the influence of flocculation in the head chest of the machine (addition 3x.sub.2) on the resistance to delamination of the support coated on two faces.

A second aspect of the tests carried out was to demonstrate that it was possible to approach, and even attain, dimensional stability of the impregnated glass webs, by using compositions with higher glass fiber contents (Tables X, XI, XIV and XV).

It is recalled that another possibility for obtaining better dimensional stability is the chemical treatment of the cellulose of the support by an appropriate size-press which the man skilled in the art can adapt as a function of the absorption of the support and the physical characteristics desired.

Such a treatment therefore makes it possible, for a comparable dimensional stability, to substantially reduce the proportion of glass fibers in the support.

This reduction in the proportion of glass fibers leads to a support presenting a greater density and consequently a better resistance to delamination which makes it possible to envisage a reduction in the latex content.

These tests have also shown that a resistance to delamination of 350 to 400 g/cm for a support coated on two faces rendered the latter sufficiently difficult to delaminate to be substituted for the impregnated glass webs.

These results explain the possibilities of orientation towards formulae less rich in latex.

However, tests MP 19474 and 19487 demonstrate the loss of dimensional stability when the quantity of latex passes from 42.5 parts by weight (MP 19474) to 37 parts by weight (MP 19487) for 100 parts by weight of basic mixture.

The dimensional stability becomes insufficient to envisage satisfactory use of the support to replace the impregnated glass web.

According to the invention, after "step 1" described hereinabove, it is advantageous to effect an additional treatment of "step 2" for the purpose of further improving:

the surface state (elimination of picking or extraction of the glass fibers); the properties of "barrier" to water, to plasticizers; anti-rot; mechanical strength; rigidity or suppleness, therefore the characteristics of curl or pliability.

To overcome curl of the products coated with plastisol on one face on the front side, a treatment of step 2 may preferably be effected on the reverse side.

These step 2 treatments may be operations of coating, impregnation, surfacing, envisaging the deposit of chemical components on the surface or at the core (by pulverization, size-press, coating machine with blades or rollers, etc.). Particular mention will be made of the addition of latex or plasticizer by size-press.

Heat and/or mechanical treatments may also be effected, such as glazing or cold or hot calendering.

The man skilled in the art knows these techniques and will know how to choose the products to be used as a function of the desired characteristic.

The product will generally be deposited at a rate of 10 to 100 g/m.sup.2 (wet state), or 2 to 40 g/m.sup.2 after drying (preferably 2 to 20 g/m.sup.2) in the case of treatment on one face, and 3 to 60 g/m.sup.2 in the case of treatment on both faces.

It may be particularly advantageous here to effect a size-press treatment in order further to improve the resistance to delamination, particularly by adding an appropriate latex which the man skilled in the art will be able to choose as a function of the desired purpose.

PRODUCTS MENTIONED IN THE TABLES

Glass fibers A

VETROTEX fibers with a length of 4.5 mm and diameter 10 .mu.m

Glass fibers B

VETROTEX fibers with a length of 3 mm and diameter 7 .mu.m

Calcium carbonate PR.4

Calcium carbonate of BLANCS MINERAUX DE PARIS mean granulometry: 3 .mu.m

Calcium carbonate OMYALITE 60

Calcium carbonate of OMYA mean granulometry: 1.5 .mu.m

References of the tests

F: Handsheets MP: Test machines E: Industrial tests TABLE I______________________________________(1) Composition (parts by dry weight): MP 17062 MP 17071Basic mixture non-filled filled(fibers + filler) 100 140______________________________________Fibrous mixture 100 100 of which: cellulose (d) 69.2 69.2Glass fibers 30.8 30.8Filler (talc) (*) 0 40Flocculant No. 1 (a) 4 4Latex (e) 100 100Flocculant No. 2 (b) 1.5 1.5Flocculant No. 3 X (c) 0.4 0.4(at the head)% Latex/basic mixture 100% 71.4%______________________________________ E 1021 E 1043Basic mixture non-filled filled(fibers + filler) 100 125______________________________________Fibrous mixture 100 100 of which: cellulose (d) 69.2 69.2of which: glass fiber 30.8 30.8Filler (talc) 0 25Flocculant No. 1 (a) 4 4Latex (e) 100 100Flocculant No. 2 (b) 1 1Flocculant No. 3 (c) X 0.8 0.8% latex/basic mixture 100% 80%______________________________________Notes:X % by dry weight with respect to the total dry composition.Glass fiber: Vitrofil 4 mmThe filler, when it is present, is introduced after the fibers andbefore flocculant No. 1.(*) Talc has been used for its particularly attractive cost price,but the man skilled in the art will know how to adapt the processfor other inorganic fillers. To this end, reference may be madeto the list of examples of fillers shown in Table VI hereinafter.(a) "Nadavin LT" polyamine/polyamide-epichlorohydrin(b) (c) polyacrylamide of high molecular weight(d) fibers of cellulose of conifers, treated with sodium hydroxide,bleached 25.degree. SR(e) latex: vinyl acetate 54-60 (% by weight) ethylene 10-16 vinyl chloride 27-33 copolymerE: industrial test TABLE II______________________________________ MP 10762 MP 17071 E 1021 E 1043______________________________________Raw paperGrammage (g/m.sup.2) 225 217 217 241Thickness (.mu.m) 361 302 337 354Bulk (cm.sup.3 /g) 1.69 1.39 1.55 1.47Paper after double-face coating of PVC and gelification at 200.degree.C.:Resistance to 400 to 350 300 to 350 340 245delamination (*)(g/cm)______________________________________ (*) Definition valid for the whole of the present Application. Measure by means of a dynamometer expressing the force exerted on 1 cm width to separate in its mass the support previously coated with PVC on its two faces, with incipient cleavage in the mass of the support. TABLE III______________________________________Flocculating agents or precipitantsRefer-ences Type of flocculants or precipitants______________________________________P 1 Aluminium sulfateP 2 Aluminium polychlorideP 3 Sodium and calcium aluminateP 4 Mixture of polyacrylic acid and of polyacrylamide in 5-30% solution (weight/volume)P 5 Polyethyleneimine in 2-50% solution (weight/volume)P 6 Copolymer of acrylamide and .beta.-methacrylyloxyethyl- trimethylammonium methylsulfateP 7 Polyamine-epichlorohydrin resin and diamine-propyl- methylamine in 2-50% solutionP 8 Polyamide-epichlorohydrin resin manufactured from epichlorohydrin, adipic acid, caprolactam, di- ethylenetriamine and/or ethylenediamine, in 2-50% solutionP 9 Polyamide-polyamine-epichlorohydrin resin manufactured from epichlorohydrin, dimethyl ester, adipic acid and diethylenetriamine, in 2-50% solutionP 10 Polyamide-epichlorohydrin resin manufactured from epi- chlorohydrin, diethylenetriamine, adipic acid and ethyleneimineP 11 Polyamide-epichlorohydrin resin manufactured from adipic acid, diethylenetriamine and a mixture of epichlorohydrin and dimethylamine in 2-50% solutionP 12 Cationic polyamide-polyamine resin manufactured from triethylenetriamineP 13 Products of condensation of aromatic sulfonic acids with formaldehydeP 14 Aluminium acetateP 15 Aluminium formateP 16 Mixture of aluminium acetate, sulfate and formate______________________________________ N.B.: When it is question of solutions, these are aqueous solutions. TABLE IV______________________________________Examples of formulations according to the inventionTest MP 17843 MP 18122 MP 18097______________________________________ Basic mixtureCellulose fibers 13.5 (1) 17.5 (1) 23.2 (1)(parts by dry weight)Non-cellulosic fibers 7.5 (2) 9.7 (2) 14.0 (2)(parts by dry weight)Fillers 79 (3) 72.8 (3) 62.8 (3)(parts by dry weight)Latex 56.4 (4) 72.8 (4) 104.7 (4)(parts by dry weight)Flocculantsaddition 1 2 2.5 3.5(parts by dry weight)addition 2 (x.sub.1) 0.3 0.36 0.52(parts by dry weight)addition 3 (x.sub.2) (5) 0.25 0.5 0.7______________________________________ Notes: (1) Cellulose fibers of conifers, treated with sodium hydroxide, bleached refined to 20.degree. SR (2) Glass fibers "A"- (3) Talc (4) Latex terpolymer: vinyl acetate/ethylene/vinyl chloride (5) % dry weight with respect to the total dry composition. TABLE V__________________________________________________________________________Properties of the products obtained from the formulationsTests MP 17843 MP 18122 MP 18097__________________________________________________________________________Characteristics:Raw papers(without stoving)grammage (g/m.sup.2) 452 312 296thickness (.mu.m) 495 369 451bulk (cm.sup.3 /g) 1.09 1.18 1.52Papers coated with PVCon 1 face indelaminable indelaminable indelaminableResistance to delamination (g/cm)on 2 faces >500 >500 indelaminableResistance to delamination (g/cm)Paper stoved for 2 mins. at 200.degree. C.pliability good good gooddimensional stability in water for 8 mins. cross direction 0.10% 0.13% 0.10%stability to humidityElongation in cross direction between 15 and 65% 0.06% 0.07% 0.07%Elongation in cross direction between 15 and 95% 0.16% 0.17% 0.19%__________________________________________________________________________ TABLE VI______________________________________Examples of formulations according to the inventionTest MP 19069 MP 18713 MP 18253______________________________________ Basic mixture = 100Cellulose fibers 17.6 (1) 17.6 (1) 17.6 (1)(parts by dry weight)Non-cellulosic fibers 9.1 (2) 9.1 (2) 9.1 (2)(parts by dry weight)Fillers 73.3 (3) 73.3 (6) 73.3 (7)(parts by dry weight)Latex 73.3 (4) 73.3 (4) 73.3 (4)(parts by dry weight)Flocculantsaddition 1 2.4 2.4 2.4(parts by dry weight)addition 2 (x.sub.1) 0.37 0.37 0.37(parts by dry weight)addition 3 (x.sub.2) (5) 0.6 0.5 0.3______________________________________ Notes: (1) Cellulose fibers of conifers, treated with sodium hydroxide, bleached refined to 20.degree. SR (2) Glass fibers "A"- (3) Calcium carbonate PR4 (4) Latex terpolymer: vinyl acetate/ethylene/vinyl chloride (5) % by dry weight with respect to the total dry composition. (6) Aluminium hydroxide (7) Talc TABLE VII__________________________________________________________________________Properties of the products obtained from the formulationsTests MP 19069 MP 18713 MP 18253__________________________________________________________________________Characteristics:Raw papers(without stoving)grammage (g/m.sup.2) 314 284 284thickness (.mu.m) 330 319 301bulk (cm.sup.3 /g) 1.05 1.12 1.05Papers coated with PVCon 1 face indelaminable indelaminable indelaminableResistance to delamination (g/cm)on 2 faces >1000 900 580Resistance to delamination (g/cm)Paper stoved for 2 mins. at 200.degree. C.pliability good good gooddimensional stability in water for 8 mins. cross direction 0.10% 0.08% 0.10%stability to humidityElongation in cross direction between 15 and 65% 0.08% 0.07% 0.10%Elongation in cross direction between 15 and 95% 0.16% 0.14% 0.17%__________________________________________________________________________ TABLE VIII__________________________________________________________________________Examples of formulations according to the inventionTest MP 19069 MP 19077 MP 19454 MP 19456 MP 19474 MP 19487__________________________________________________________________________ basic mixture = 100Cellulose fibers 17.6 (1) 17.6 (1) 17.6 (1) 17.6 (1) 17.6 (1) 17.6 (1)(parts by dry weight)Non-cellulosic fibers 9.1 (2) 9.1 (2) 9.1 (2) 9.1 (2) 9.1 (2) 9.1 (2)(parts by dry weight)Fillers 73.3 (3) 73.3 (3) 73.3 (6) 73.3 (6) 73.3 (6) 73.3 (6)(parts by weight)Latex 73.3 (4) 61.1 (4) 48.9 (4) 48.9 (4) 42.8 (4) 37 (4)(parts by dry weight)Flocculantsaddition 1 2.4 2.4 2.4 2.4 1.7 1.2(parts by dry weight)addition 2 (x.sub.1) 0.37 0.37 0.27 0.27 0.27 0.19(parts by dry weight)addition 3 (x.sub.2) (5) 0.6 0.5 0.6 0.3 0.4 0.3__________________________________________________________________________ Notes: (1) Cellulose fibers of conifers, treated with sodium hydroxide, bleached refined to 20.degree. SR (2) Glass fibers VETROTEX (3) Calcium carbonate PR4 (4) Latex terpolymer: vinyl acetate/ethylene/vinyl chloride (5) % by dry weight with respect to the total dry composition. (6) Calcium carbonate OMYALITE 60 TABLE IX__________________________________________________________________________Properties of the products obtained from the formulationsTests MP 19069 MP 19077 MP 19454 MP 19456 MP 19474 MP__________________________________________________________________________ 19487Characteristics:Raw papers(without stoving)grammage (g/m.sup.2) 314 302 258 284 280 273thickness (.mu.m) 330 298 302 318 314 288bulk (cm.sup.3 /g) 1.05 1.00 1.17 1.11 1.12 1.05Papers coated with PVCon 1 face indelami- indelami- indelami- indelami- indelami- indelami-Resistance to delamination (g/cm) nable nable nable nable nable nableon 2 faces indelami- indelami- indelami- 450 620 520Resistance to delamination (g/cm) nable nable nable (>1000) (>1000) (>1000)Paper stoved for 2 mins. at 200.degree. C.pliability good good good good good gooddimensional stability in water for 8 mins. cross direction 0.10% 0.12% 0.10% 0.09% 0.10%stability to humidityElongation in cross direction between 15 and 65% 0.08% 0.10% 0.10% 0.11% 0.10% 0.14%Elongation in cross direction between 15 and 95% 0.16% 0.20% 0.18% 0.18% 0.17% 0.22%__________________________________________________________________________ TABLE X______________________________________Examples of formulations according to the inventionTest MP 19377 MP 19378 MP 19379______________________________________ Basic mixture = 100Cellulose fibers 16.5 (1) 16.5 (1) 16.5 (1)(parts by dry weight)Non-cellulosic fibers 15 (2) 15 (2) 15 (2)(parts by dry weight)Fillers 68.5 (3) 68.5 (3) 68.5 (3)(parts by dry weight)Latex 57.1 (4) 57.1 (4) 57.1 (4)(parts by dry weight)Flocculantsaddition 1 2.3 2.3 2.3(parts by dry weight)addition 2 (x.sub.1) 0.34 0.34 0.34(parts by dry weight)addition 3 (x.sub.2) (5) 0.5 0.6 0.4______________________________________ Notes: (1) Cellulose fibers of conifers, treated with sodium hydroxide, bleached refined to 20.degree. SR (2) Mixture of glass fibers VETROTEX in commercial weight 1/2 A + 1/2 B (3) Calcium carbonate (OMYALITE 60) (4) Latex terpolymer: vinyl acetate/ethylene/vinyl chloride (5) % by dry weight with respect to the total dry composition. TABLE XI__________________________________________________________________________Properties of the products obtained from the formulationsTests MP 19377 MP 19378 MP 19379__________________________________________________________________________Characteristics:Raw papers(without stoving)grammage (g/m.sup.2) 285 294 286thickness (.mu.m) 298 305 315bulk (cm.sup.3 /g) 1.04 1.03 1.10Papers coated with PVCon 1 face indelaminable indelaminable indelaminableResistance to delamination (g/cm)on 2 faces 730 700 800Resistance to delamination (g/cm)Paper stoved for 2 mins. at 200.degree. C.pliability good good gooddimensional stability in water for 8 mins. cross direction <0.08% <0.08% <0.08%stability to humidityElongation in cross direction between 15 and 65% 0.065% 0.055% 0.06%Elongation in cross direction between 15 and 95% 0.12% 0.10% 0.11%__________________________________________________________________________ TABLE XII__________________________________________________________________________Examples of formulations according to the inventionTest F270884/1A F270884/1B F300884/1A F300884/1B__________________________________________________________________________ basic mixture = 100Cellulose fibers 16.5 (1) 16.5 (1) 18.1 (1) 18.1 (1)(parts by dry weight)Non-cellulosic fibers 14.7 (2) 14.7 (2) 16.1 (2) 16.1 (2)(parts by dry weight)Fillers 68.8 (3) 68.8 (3) 65.8 (3) 65.8 (3)(parts by dry weight)Latex 57.3 (4) 57.3 (4) 53.3 (4) 53.3 (4)(parts by dry weight)Flocculantsaddition 1 2.3 2.3 2.5 2.5(parts by dry weight)addition 2 (x.sub.1) 0.34 0.34 0.37 0.37(parts by dry weight)addition 3 (x.sub.2) (5) 0.75 0.875 0.75 0.875__________________________________________________________________________ Notes: (1) Cellulose fibers of conifers, treated with sodium hydroxide, bleached refined to 20.degree. SR (2) Mixture of glass fibers VETROTEX 1/3 A + 2/3 B (3) Calcium carbonate OMYALITE 60 (4) Latex terpolymer: vinyl acetate/ethylene/vinyl chloride (5) % by dry weight with respect to the total dry composition. TABLE XIII__________________________________________________________________________Properties of the products obtained from the formulationsTests F270884/1A F270884/1B F300884/1A F300884/1B__________________________________________________________________________Characteristics:Raw papers(without stoving)grammage (g/m.sup.2) 257 265 256 261thickness (.mu.m) 271 271 285 277bulk (cm.sup.3 /g) 1.05 1.02 1.11 1.06Papers coated with PVCon 1 face indelaminable indelaminable indelaminable indelaminableResistance to delamination (g/cm)on 2 faces 400 indelaminable 440 indelaminableResistance to delamination (g/cm)Paper stoved for 2 mins. at 200.degree. C.pliability good good good gooddimensional stability in water for 8 mins. cross direction -- -- -- --stability to humidityElongation in cross direction between 15 and 65% -- -- -- --Elongation in cross direction between 15 and 95% -- -- -- --__________________________________________________________________________ TABLE XIV______________________________________Examples of formulations according to the inventionTest MP 19163 MP 19377 E 1153 E 1145______________________________________ Basic mixture = 100Cellulose fibers 15.7 (1) 16.5 (1) 16.5 (1) 16.5 (1)(parts by dry weight)Non-cellulosic fibers 18.9 (2) 15 (2) 14.6 (6) 14.6 (7)(parts by dry weight)Fillers 65.4 (3) 68.5 (3) 68.9 (3) 68.9 (3)(parts by dry weight)Latex 54.5 (4) 57.1 (4) 57.4 (4) 57.4 (4)(parts by dry weight)Flocculantsaddition 1 2.2 2.3 2.3 2.3(parts by dry weight)addition 2 (x.sub.1) 0.33 0.34 0.34 0.34(parts by dry weight)addition 3 (x.sub.2) (5) 0.6 0.5 0.4 0.5______________________________________ Notes: (1) Cellulose fibers of conifers, treated with sodium hydroxide, bleached refined to 20.degree. SR (2) Glass fibers VETROTEX: mixture in commercial weight 1/2 A + 1/2 B (3) Calcium carbonate OMYALITE 60 (4) Latex terpolymer: vinyl acetate/ethylene/vinyl chloride (5) % by dry weight with respect to the total dry composition. (6) Glass fibers VETROTEX: mixture in commercial weight 1/3 A + 2/3 B (7) Glass fibers VETROTEX: B TABLE XV__________________________________________________________________________Properties of the products obtained from the formulationsTests MP 19163 MP 19377 3 1153 E 1145__________________________________________________________________________Characteristics:Raw papers(without stoving)grammage (g/m.sup.2) 205 285 286 275thickness (.mu.m) 261 298 288 300bulk (cm.sup.3 /g) 1.27 1.04 1.00 1.09Papers coated with PVCon 1 face indelaminable indelaminable indelaminable indelaminableResistance to delamination (g/cm)on 2 faces 515 730 495 450Resistance to delamination (g/cm)Paper stoved for 2 mins. at 200.degree. C.pliability good good good gooddimensional stability in water for 8 mins. cross direction <0.08% <0.08% <0.08% <0.08%stability to humidityElongation in cross direction between 15 and 65% 0.06% 0.065% 0.07% 0.07%Elongation in cross direction between 15 and 95% 0.11% 0.12% 0.13% 0.13%__________________________________________________________________________ TABLE XVI______________________________________INORGANIC FILLERS WHICH MAY BE USEDRefer-ences Type of filler______________________________________C1 Talc: Complex magnesium silicate - particles of 1 to 50 .mu.m, preferably 2 to 50 .mu.m - specific weight from 2.7 to 2.8C2 Kaolin: Complex aluminium hydrate silicate - particles of 1 to 50 .mu.m, preferably 2 to 50 .mu.m - specific weight 2.58C3 Natural calcium carbonate: particles of 1.5 to 20 .mu.m, preferably 2 to 20 .mu.m - specific weight: 2.7C4 Precipitated calcium carbonate: particles of 1.5 to 20 .mu.m, preferably 2 to 20 .mu.m - specific weight: 2.7C5 Natural barium sulfate: particles of 2 to 50 .mu.m- specific weight about 4.4-4.5C5 Precipitated barium sulfate: particles 2 to 20 .mu.m - specific weight about 4.35C6 Silica of diatoms: particles of 2 to 50 .mu.m - specific weight about 2 to 2.3C7 White satin: hydrated calcium sulfoaluminateC8 Natural calcium sulfate: particles of 2 to 50 .mu.m - specific weight about 2.32-2.96C9 Aluminium hydroxide: particles of 2 to 50 .mu.mC10 Sodium and calcium aluminate: particles of 1 to 20 .mu.m - specific weight 2.2C11 Sodium silicoaluminate: particles of 1 to 20 .mu.m - specific weight about 2.12C12 Rutile titanium: particles of 0.5 to .10 .mu.m - specific weight about 4.2C13 Octahedrite titanium: particles of 0.5 to 10 .mu.m - specific weight about 3.9C14 Mixtures C1-C6 (70:30) by weightC15 Mixture C1-C3 (50:50) by weightC17 Mixture C1-C12 (95:5) by weightC18 Magnesium hydroxide: particles of 2 to 50 .mu.m______________________________________ Note: The specific weight is expressed in g/ml.

Claims

1. A paper sheet which contains, in parts by dry weight, 40 to 105 parts of latex and 100 parts of a basic mixture comprising 60 to 40 parts of cellulosic fibers having an SR of 15-35 and non-cellulosic fibers including short inorganic fibers, said short inorganic fibers being glass fibers and representing 40 to 90% by dry weight of said cellulosic fibers, and said sheet having a dimensional stability of not more than 0.13%, and a resistance to delamination of greater than 350 g/cm, and wherein the fillers or flocculant are not calcium hydroxide.

2. The paper sheet of claim 1, wherein the inorganic fibers are glass fibers having a length of less than 4 mm.

3. The paper sheet of claim 1 wherein the fillers are inorganic fillers selected from the group consisting of talc, kaolin, calcium carbonate, barium sulfate, silica of diatoms, satin white, calcium sulfate, aluminum hydroxide, sodium aluminate, calcium aluminate, sodium silicoaluminate, rutile, octahedrite, magnesium hydroxide and mixtures thereof.

4. A paper sheet which contains, in parts by dry weight; 40 to 105 parts of latex and 100 parts of a basic mixture comprising 60 to 80 parts of fillers and 20 to 40 parts of cellulosic fibers having a SR of 15-35 and non-cellulosic fibers, said non-cellulosic fibers being glass fibers and representing 40 to 60% by dry weight of said cellulosic fibers, said sheet having a dimensional stability of not more than 0.13% and a resistance to delamination of greater than 350 g/cm, and wherein said sheet does not contain calcium hydroxide as a flocculant or filler.

5. The sheet of claim 4, wherein said non-cellulosic fibers are glass fibers or rock wool.

6. The sheet of claim 4, wherein said non-cellulosic fibers are glass fibers.

7. The sheet of claim 6, wherein said glass fibers have a length of between about 3 and 12 mm, and a diameter of about 5 to 15 .mu.m.

8. The sheet of claim 6 wherein said glass fibers have a length of between about 3 and 6 mm and a diameter of about 5 to 15 .mu.m.

9. The sheet of claim 6, wherein the latex is selected from styrene-butadiene copolymers, acrylic and preferably vinyl latices.

10. The sheet of claim 9, wherein the latex is a terpolymer of vinyl acetate, ethylene and vinyl chloride.

11. The sheet of claim 6, wherein the filler is selected from calcium carbonate and aluminum hydroxide.

12. The paper sheet of claim 4 wherein the fillers are inorganic fillers selected from the group consisting of talc, kaolin, calcium carbonate, barium sulfate, silica of diatoms, satin white, calcium sulfate, aluminum hydroxide, sodium aluminate, calcium aluminate, sodium silicoaluminate, rutile, octahedrite, magnesium hydroxide and mixtures thereof.

13. A process for manufacturing a paper sheet having a dimensional stability of not more than 0.13% and a resistance to delamination of at least 350 g/cm, in a paper-making machine having a headbox downstream of a chest, said process comprising the steps of preparing an aqueous dispersion by adding successively the following components;

20 to 40 parts by dry weight of a fibrous mixture comprising cellulosic fibers refined between 15 and 35 SR and glass fibers in a content representing 40-60% in weight of said cellulosic fibers;

60 to 80 parts by dry weight of fillers so as to obtain 100 parts of a basic mixture containing said fibrous mixture and said fillers;

a first addition of a flocculating amount of flocculant;

40 to 105 parts by dry weight of latex selected from acrylic and preferably vinyl styrene-butadiene copolymers, particularly vinyl chloride/ethylene/vinyl acetate copolymer or plasticized acrylate/vinyl chloride copolymer;

a second addition of a flocculating amount of flocculant in said chest; and

a third addition of a flocculating amount of flocculant in said headbox, and of passing said aqueous dispersion on said paper-making machine and wherein calcium hydroxide is not used as the filler or the flocculant.

14. The process of claim 13, wherein said sheet undergoes at least one further treatment selected from operations of coating, impregnation, surfacing, glazing, cold or hot calendering.

15. The process of claim 13, wherein said aqueous dispersion comprises in parts by dry weight:

100 parts of a basic mixture made by mixing:

17.6 parts of cellulose fibers

9.1 parts of glass fibers

73.3 parts of calcium carbonate;

61.5 parts of latex terpolymer of vinyl acetate/ethylene/vinyl chloride;

2.4 parts of said first addition of flocculant;

0.37 parts of said second addition of flocculant;

0.5% of said third addition of flocculant by dry weight with respect to the total dry weight.

16. The process of claim 13, wherein said aqueous dispersion comprises in parts by dry weight:

100 parts of a basic mixture made by mixing:

17.6 parts of cellulose fibers

9.1 parts of glass fibers

73.3 parts of calcium carbonate;

42.8 parts of latex terpolymer of vinyl acetate/ethylene/vinyl chloride;

1.7 parts of said first addition of flocculant;

0.27 parts of said second addition of flocculant;

0.4% of said third addition of flocculant by dry weight with respect to the total dry weight.

17. The process of claim 13, wherein said aqueous dispersion comprises in parts by dry weight:

100 parts of a basic mixture made by mixing:

16.5 parts of cellulose fibers

14.6 parts of glass fibers

68.9 parts of calcium carbonate;

57.4 parts of latex terpolymer of vinyl acetate/ethylene/vinyl chloride;

2.3 parts of said first addition of flocculant;

0.34 parts of said second addition of flocculant;

0.4% of said third addition of flocculant by dry weight with respect to the total dry weight.

18. The process of claim 13, wherein said aqueous dispersion comprises in parts by dry weight:

100 parts of a basic mixture made by mixing:

16.5 parts of cellulose fibers

14.6 parts of glass fibers

68.9 parts of calcium carbonate;

57.4 parts of latex terpolymer of vinyl acetate/ethylene/vinyl chloride;

2.3 parts of said first addition of flocculant;

0.34 parts of said second addition of flocculant;

0.5% of said third addition of flocculant by dry weight with respect to the total dry weight.

19. The process of claim 13 wherein the fillers are inorganic fillers selected from the group consisting of talc, kaolin, calcium carbonate, barium sulfate, silica of diatoms, satin white, calcium sulfate, aluminum hydroxide, sodium aluminate, calcium aluminate, sodium silicoaluminate, rutile, octahedrite, magnesium hydroxide and mixtures thereof.