EP0031832A1

EP0031832A1 - Sheets products and preparation process thereof.

Info

Publication number: EP0031832A1
Application number: EP80901273A
Authority: EP
Inventors: Christian Dailly; Daniel Gomez
Original assignee: Arjomari Prioux SA
Current assignee: Arjomari Prioux SA
Priority date: 1979-07-10
Filing date: 1981-02-09
Publication date: 1981-07-15
Also published as: JPH0227479B2; DK156588B; ATE11939T1; JPS56500853A; US4481075A; EP0031832B1; DE3070207D1; DK156588C; BE884712A; FR2461061A1; DK108781A; CA1163059A; WO1981000268A1

Abstract

New process, for preparing by means of a paper manufacturing technique, a thermoplastic sheet reinforced with cellulose fibres, wherein a thermoplastic powder and cellulose fibres are used in association, if necessary with other fibres, and consisting in (1) preparing an aqueous suspension from a base mixture (selected among (i) the fibres and the pulverulent thermoplastic substance when there is no non-binding mineral charge, and (ii) the fibres, the pulverulent thermoplastic substance and the non-binding mineral char harge when the latter is present), an organic binder and a flocculating agent, and with the resulting suspension, forming a sheet by wet process, which is then wrung and dried and (2) if necessary subjecting the resulting thermoplastic sheet to at least a complementary treatment, the weight ratio of pulverulent thermoplastic substance to fibres being between 0.3 and 95. Thermoplastic reinforced sheets as a novel industrial product and application thereof particularly in the firld of transformation of plastic materials.

Description

SHEET PRODUCTS AND THEIR PREPARATION PROCESS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The present invention relates to new sheet products containing a thermoplastic and cellulose fibers; it also relates to a process for the preparation of said new products and to the applications of said new products.

It has already been recommended to improve certain properties of thermoplastic substances by incorporating fibers of high elastic modulus therein. Glass, carbon, asbestos and boron fibers are therefore commonly used to reinforce certain thermoplastic substances, such as polyamides, polycarbonates, polyalkylenes (polyethylenes and polypropylenes), polyesters, polystyrenes, for the purpose of 'increase stiffness, impact resistance, tensile strength and improve dimensional stability.

Furthermore, it is known that cellulose fibers have already been used to reinforce thermosetting substances, such as urea-formaldehyde and melamine-formaldehyde resins, which have a good chemical affinity for cellulose, a circumstance which favors the dispersion of the fibers. cellulosics within the polymer (see for this purpose British Patent No. 1319 371 which describes the preparation of a sheet from cellulosic fibers and an organic powdered filler constituted by a ureaforma ldehy polymer).

Finally, it was recommended, in particular in French patent 7031148, a process for manufacturing a paper sheet, based on cellulose fibers, which may contain substantial amounts of a finely divided natural or synthetic polymer. Thus, known materials based on fibers and plastics are in two different classes: one consisting in reinforcing a thermoplastic material with relatively small amounts of a reinforcing fiber, the other consisting in modifying the properties of a paper based on cellulose fibers by incorporating into this paper a certain amount of a thermoplastic material. The present invention lies in the technical field consisting in the reinforcement of a thermoplastic material using cellulosic fibers.

Thus, the present invention describes a new technical solution to solve the problem of the dispersion of cellulosic fibers within a thermoplastic polymer, which consists in operating in a medium where said cellulosic fibers are easily dispersible: a sheet is formed by the papermaking process. from an aqueous suspension comprising the cellulosic fibers and the thermoplastic substance in powder form, on the one hand, and other essential ingredients (binder and foculant as indicated below), on the other hand.

One of the aims of the invention is to propose a thermoplastic sheet having improved mechanical properties and more precisely the important properties which are rigidity, tensile strength, impact resistance and dimensional stability.

Another object of the invention is to obtain by means of a paper machine a thermoplastic sheet which, after having been formed and dried, is capable of being subjected to an additional treatment (such as impregnation, coating, smoothing ) classic in stationery.

Another object of the invention is to improve the dimensional stability, the internal cohesion in the dry and wet state, the flexibility and the resistance to folding of a substrate made of a thermoplastic sheet which can in particular be used as a coating support for covering panels and, in particular, for flooring.

Another object of the invention is to propose a new material to the plastic processing industries in the form of granules obtained by shredding and granulation of the thermoplastic sheet produced on a paper machine according to the process.

Among the advantages of the invention, one can in particular mention:

- savings in thermoplastic material resulting from the use of materials with reinforced properties; - savings on production costs resulting from the use of machines with high hourly production (paper machines) instead of machines for manufacturing thermoplastic sheets by calendering, extrusion or coating. Among the applications of the invention, mention may in particular be made of:

the use of the thermoplastic sheet produced on a paper machine as a support for coating plasticized PVC for floor covering when the thermoplastic substance introduced into the sheet is PVC and the sheet is loaded and plasticized;

- the use of the thermoplastic sheet made on a paper machine as a calendering material;

- the use of the thermoplastic sheet made on a paper machine as a thermoforming material;

- the use of the thermoplastic sheet as a coating or coating support for printing-writing;

- transformation of the thermoplastic sheet produced on a paper machine by shredding and, optionally, granulation, into a raw material for processing by extrusion, extrusion blow molding, injection, molding.

The sheet materials according to the present invention are characterized in that they comprise:

- the constituents of a basic mixture comprising 5 to 30% by weight of cellulose fibers, 95 to 70% by weight of a powder of thermoplastic material; and

- the elements essential for the preparation of a formable sheet by application of papermaking techniques, namely essentially at least one organic binder and at least one flocculating agent.

It is possible, according to the invention, to use any cellulosic fiber or mixtures of these fibers. However, the preferred cellulosic fibers are those which are refined to a Shopper-Riegler (SR) degree of between 15 and 65. Softwood fibers are advantageously chosen, since they are more resistant than those of hardwoods. It is possible to replace part of the cellulosic fibers which constitute the basic mixture with mineral or organic fibers, natural or synthetic. Thus, in the materials according to the invention, approximately 30% of the fibers may be non-cellulosic.

In Table I below, a list of cellulosic or non-cellulosic fibers which can be used in the context of the invention has been provided.

Among the non-cellulosic fibers, mention may be made in particular of the possible use of glass fibers which are of very particular interest in that they give the sheet products according to the invention a quite remarkable dimensional stability. When it is desired to use significant amounts of these glass fibers, it has appeared desirable to simultaneously use polyvinyl alcohol fibers, insoluble in cold water, which have the function of facilitating the dispersion of the glass fibers in the aqueous suspensions.

Particularly interesting fiber mixtures consist of approximately 14 parts of cellulosic fibers, 2 parts of glass fibers and possibly 1 part of polyvinyl alcohol fibers.

All powdered thermoplastic substances (also called here thermoplastic polymers) are suitable for the preparation of the thermoplastic sheet according to the invention and, in particular, polyvinyl chloride (PVC), polyvinyl acetate (PVA), polyalkylenes - in particular high density polyethylene (HDPE), low density polyethylene (Pebd), polypropylene (PPhd; PPbd), polybutadiene and polyisoprene -, polystyrene (PS), polyamides (PA), the polymers and copolymers obtained in particular from acrylonitrile, acrylic and methacrylic acids and their esters, polycarbonate (PC), polyacetal and thermoplastic polyesters. Among the copolymers which are suitable, mention may in particular be made of acrylonitrile-styrene, methyl methacrylate-butadiene-styrene, styrene-butadiene, ABS copolymers. If necessary, the thermoplastic substance may be previously combined with a plasticizer. The preferred substance is optionally plasticized PVC. Thermoplastic powders can advantageously be used crude polymerization when their particle size is appropriate. Otherwise, it is necessary to grind them to obtain the desired particle size. Recovered plastics are also suitable provided they are properly ground. Preferably, thermoplastic powders of particle size less than or equal to 500 microns will be chosen.

In addition, part of the powder of thermoplastic material used in the base mixture can be replaced by a non-binding mineral filler. A list of non-binding mineral fillers is given, for example, in Table IV below. These fillers, commonly used in the paper industry, have particles of dimensions (average diameter) at most equal to 80 microns. The amount of non-binding filler will be at most 40% by weight relative to the weight of the powdered thermoplastic material. .

The materials according to the invention will comprise at least one organic binder essential for the constitution of the sheet according to the papermaking technique.

The organic binder bonds the constituents of the thermoplastic sheet to one another and can reinforce, if necessary, the physical properties of the sheet. Among the binders which are suitable, mention may in particular be made of those in Table II below. The preferred binders are latexes (acrylics, styrene-butadiene) and starch, in particular starch comprising, in its linear polymer component (that is to say amylose), 50 to 6000 anhydroglucose units per molecule such as, for example, native starch (obtained from potatoes) and native corn starch which contain 100 to 6000 anhydroglucose units (in the linear polymer) per molecule, and chemically modified starches or enzymatic which contain 50 to 3000 anhydroglucose units (in the linear polymer) per molecule.

The amount of usable binder is from 0.2 to about 30 parts by dry weight (advantageously 2 to 10 parts by dry weight) per 100 parts of the basic mixture (fibers and thermoplastic powder, possibly mineral filler). The materials according to the invention will also comprise at least one flocculant essential for the constitution of the sheet according to the papermaking technique.

Among the flocculants which are suitable, mention may in particular be made of metal salts, such as in particular aluminum, iron (II), iron (III), zinc and chromium salts, such as halides, sulfates and phosphates and the other substances indicated in Table III below. The preferred flocculant according to the invention is poly aluminum chloride which is a substance also known under the name of aluminum hydroxychloride, which has the general formula (OH) _y Al _x Cl _zyx and which is in particular marketed by the Company Péchiney Ugine Kuhlmann under the brand name "WAC".

The flocculant (s) will, according to the process of the invention, be used in two fractions.

The first fraction of the flocculant, which is introduced before the binder, and the binder provide a first agglomeration of the constituents of the base mixture. The purpose of the second fraction of the flocculant is to strengthen the cohesion of the constituents of the base mixture and thus improve the retention on the paper machine and the resistance of the flocs. Of course, it is possible to use either the same flocculating agent before and after the binder, or else different flocculating agents, or finally mixtures of flocculating agents. The amount of flocculant that can be used is, in total, from 0.02 to about 10 parts per 100 parts of the basic mixture.

Other conventional additives in stationery, such as water repellents, lubricants, defoamers or foam breakers, dyes, optical brighteners, antioxidants, may be present in the sheets according to the invention. Table V below provides a non-limiting list of water repellents (the preferred products being the products H 1 and H 4 of said table).

Table VII below provides a non-limiting list of auxiliary agents which can be used according to the invention. We also know that a certain number of plastic materials exhibit optimal properties only to the extent where these materials are plasticized. It is therefore possible to additionally introduce into the products according to the invention from 10 to 100% by weight, relative to the weight of the thermoplastic material (more particularly in the case of PVC), of plasticizer. In practice, it is known that the plasticization of thermoplastic materials can be carried out either by internal plasticization, or by external plasticization.

The internal plasticization is carried out during the manufacture of the thermoplastic material by copolymerization of "flexible" and "hard" polymers.

The external plasticization is carried out by incorporating into the thermoplastic material an agent having good solvent power and swelling vis-à-vis said thermoplastic material used. It is possible, according to the present invention, to plasticize by one or the other mode described above. The external plasticizers which can be used, in particular in the case of PVC, are adipic esters (dibutyl adipate, benzyloctyl adipate), phosphoric esters (phosphates of tricresyl, triphenyl, diphenylsylenile, trichlorethyl, diphenyloctyl, trioctyl) phthalic esters (dimethyl, diethyl, dibutyl, dinonyl, benzylbutyl, dicylohexyl phthalates), sulfonic esters, chlorinated paraffins. With PVC powder, di- (2-ethylhexyl) -phthalate (preferably DOP) will preferably be used.

The present invention also relates to a process for the preparation of the sheets as described above.

The process according to the invention for papermaking a thermoplastic sheet reinforced with cellulosic fibers, in which a thermoplastic powder and cellulosic fibers are used, is characterized in that: 1) an aqueous suspension is prepared from a base mixture [chosen from the group consisting of (i) the fibers and the powdered thermoplastic substance when there is no non-binding mineral filler and (ii) the fibers, the powdered thermoplastic substance and the filler non-binding mineral when the latter is present], an organic binder and a flocculating agent, then forms, by means of the suspension thus obtained, a wet sheet which is wrung and dried; and 2) if necessary, the thermoplastic sheet thus obtained is subjected to at least one additional treatment.

The method according to the invention is implemented in stage 1) from four essential means, namely the cellulose fibers, the powdered thermoplastic substance, the organic binder and the flocculating agent. Other means can intervene in stage 1), namely a non-binding mineral filler, a plasticizing agent, an antistatic agent, an antioxidant agent, a porophore agent (which plays in particular the role of blowing agent, in particular for PVC), a dispersing agent (for the thermoplastic substance), an emulsifying agent (to emulsify the plasticizing agent) and one or more conventional additives in stationery, such as water-repellent agents, anti-foaming agents and / or foam breakers, dyes, optical brighteners, retention agents, lubricants.

To carry out stage 1), it is important not to introduce all of the flocculant before the organic binder into the aqueous suspension of the basic mixture. It is rather recommended, to reduce the losses under fabric, either to introduce the flocculant after the binder, or preferably to introduce a part of the flocculating agent before the addition of the binder, then the rest after the binder.

Obviously, the relative amounts of the various constituents (fibers, powder of thermoplastic material, possibly non-binding filler, flocculant, binder, new flocculant and other additives) must be in accordance with what is mentioned above.

According to a specific characteristic of stage 1), 0.02 to 10 parts by weight of flocculating agent are introduced per 100 parts by weight of MB. Preferably, the following will be introduced into the aqueous suspension comprising 100 parts by weight of MB:

(i) 0.01 to 4 parts (advantageously 0.01 to 3 parts) by weight of flocculating agent, (ii) the organic binder, (iii) 0.01 to 6 parts (advantageously 0.01 to 5 parts) by weight of flocculating agent. The thermoplastic polymer can be used either in the form of a dry powder, or in the form of a dispersion in water; in the latter case, the dispersion may comprise a small proportion, for example from 0.1 to 1%, of a dispersing agent. For the incorporation of plasticizer in the thermoplastic sheet (in particular by a surface treatment), it is advantageous to emulsify the plasticizer by means of a conventional emulsifier of the textile or paper industry. For example, the ethylpolyglycol ether derivatives which are particularly advantageous for obtaining a homogeneous and stable aqueous emulsion will be chosen. The dose of emulsifying agent will be of the order of 0.05 to 2% by weight, relative to the weight of plasticizer. The emulsification is obtained by adding the plasticizer in water containing the emulsifying agent and by stirring with a mixer type device rotating at more than 250 rpm. This mixture with variable concentration of dioctylphthalate in water will contain, for example, from 100 to 990 g of dioctylphthalate per 1000 g of mixture. This technique is particularly advantageous when the plasticizer is added in stage 1) of the process.

But the most interesting method for incorporating the plasticizer is to carry out this incorporation in stage 2) of the method using the technique known as the size-press as mentioned below.

If necessary, an antioxidant may be introduced in stage 1) to prevent aging of the thermoplastic substance entering the thermoplastic sheet according to the invention, in particular to prevent surface cracks in the polystyrene, yellowing and the reduction of mechanical properties. PVC, under the action of UV rays. Among the suitable antioxidants, it is possible to use 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole, preferably at a dose of 0.1 to 5% by weight, relative to the weight of the thermoplastic substance. in powder.

If necessary, introduce either in stage 1) or in stage 2) an antistatic agent.

Other conventional additives in stationery can intervene, if necessary, in stage 1) such as, for example, water-repellent agents (also called bonding agents), lubricants, defoamers or foam breakers, colorants, optical brighteners. Among the suitable water repellents, mention may in particular be made of those in Table V below and, among the auxiliary agents, those mentioned in Table VII given below. The water-repellent agent is preferably introduced in stage 1) after the organic binder and before the 2nd fraction of flocculant The amount of water-repellent agent can be between 0.05 and 10 (advantageously between 0.05 and 5 and, preferably, between 0.1 and 3) parts by dry weight per 100 parts by weight of MB. The preferred waterproofing agents are the products H 1 and H 4 of Table V below.

If necessary, at step 1), at the same time as or after the water-repellent agent, are introduced at least one auxiliary agent chosen in particular from the group consisting of resistance agents in the wet state (0.1 5 parts by weight per 100 parts by weight of MB), anti-foaming agents (0.05 to 0.2 parts by weight per 100 parts by weight of MB), dyes (in an amount sufficient for the desired effect), fungicidal agents and, where appropriate, lubricating agents (0.2 to 5 parts by weight per 100 parts by weight of MB).

By carrying out stage 1), a thermoplastic sheet is obtained having a grammage between 15 and 1500 g / m ² .

The sheet obtained in stage 1) is subjected, if necessary, in stage 2) to one or more additional treatments, on a paper machine or outside of a paper machine for in particular:

- improve the appearance, the surface uniformity, increase the surface resistance and standardize the mechanical properties,

- to reinforce the rigidity or the flexibility, - to obtain the particular properties such as fireproofing, nonadherence, greasability, heat-sealability and special effects, such as barrier effects and rot-proofing (resistance to bacteria and fungi). The means to be implemented, for this purpose, are in particular the size-press, or sizing press, the roll coater, the roll coater, the metal coater, air coater or the coater scraper. In addition to these means, there are processing means for the exploitation of thermoplasticization on a paper machine or outside the paper machine (hot air oven, gas oven, infrared, hot calendering) and for improving the 'surface uniform: smoothing, calendering and / or graining. In general, stage 2) may include the contribution of at least one substance chosen from the group consisting of mineral fillers, organic binders, plasticizers, antioxidants, antistatics and conventional adjuvants of the stationery, such as, in particular, sizing agents, dispersing agents, pigments, fluorescent agents, tinting dyes, lubricating agents, viscosity modifying agents, anti-foaming agents, insolubilizing agents and antibiotics by means of '' an aqueous bath of 10 to 600 g / 1. Of course, stage 2) will be implemented according to the objectives sought.

From a practical point of view, it will be possible to use in stage 2) at least one binder, in particular a binder from Table VI below and, if necessary, at least one substance chosen from non-binding mineral fillers (as described below). above in step 1)), auxiliary agents (such as those given in Table VII below), plasticizers and emulsifiers for plasticizers.

The quantity of dry matter that can be deposited in stage 2) is in particular between 1 and 200 g / m ² , taking into account the different coating means that can be used and the final properties required. As an indication, in a non-pigmented size press, 1 to 10 g / m ² of dry matter may be applied. By pigmented coating with a Champion doctor blade, you can apply between 3 and 30 g / m ² of dry matter on one side in a single pass. On an air space, 5 to 40 g / m ² of dry matter can be applied to one side in a single pass. In rigid or flexible trailing blade, oonn ppoouurrrraa to apply 5 to 40 g / m of dry matter on one side in a single pass The operating conditions of stage 2) for the supply of the agents mentioned above are those described in European patent application No. 79400405.1 of June 19, 1979.

The best mode of implementing the method according to the invention has been described below.

Stage 1) includes the following stages. a) Is introduced with stirring into an aqueous suspension of fibers at 10-50 g / 1 (cellulosic fibers refined to a degree SR between 15 and 65 combined, where appropriate, with other fibers, in particular glass fibers and of PVA) the powdered thermoplastic substance having a particle size less than or equal to 500 microns (if necessary, said thermoplastic substance has been previously dispersed in water by means of a dispersing agent). b) If necessary, a non-binding mineral filler is added to the suspension obtained. c) The flocculant is diluted in water from 1 to 10 times. This is a preferably mineral flocculant (polychloride of aluminum) which is introduced into the resulting suspension in an amount of 0.01 to 4 parts (preferably 0.01 to 3 parts) by weight per 100 parts by weight of MB. d) The binder (which can in particular be native starch previously cooked at 80-90 ° C, or a latex in aqueous emulsion at a concentration of 15 to 100 g / l) is then incorporated into the resulting suspension with stirring either discontinuously, or preferably continuously in the head circuits of the paper machine. e) Can then be incorporated either discontinuously in the mixing vat, or continuously in the overhead circuits: an antioxidant, an antistatic agent, a water repellant, a whitening agent, one or more dyes, a anti-foaming agent and possibly the lubricant. f) The second fraction of the flocculating agent is then introduced, before the headbox, at a rate of 0.01 to 6 parts (preferably 0.01 to 5 parts) by weight per 100 parts by weight of MB. The flocculant plays an important role at this stage in flocculation, retention and drainage. These last two properties can, if necessary, be improved by also adding a conventional retention agent from the stationery industry. g) The resulting suspension is introduced into the headbox and a thermoplastic sheet is formed by wringing on a canvas as described, for example, in the aforementioned European patent application. h) After passing over the canvas, a conventional wet part pressing is carried out by means of one or more multiple presses (dressed or naked) at drying at a temperature of the order of 100 to 150 ° C. and, if necessary, the use of thermoplasticization (for example treatment at 130-280 ° C). The sheet obtained in stage 1) which has a grammage of between 15 and 1500 g / m 2 is submitted, if necessary, in stage 2). Stage 2) comprises one or more treatments on the paper machine or outside the paper machine.

The quantities of materials deposited on the fibrous sheet during these surface treatments are very variable and obviously depend on the objectives sought and the manufacturing means used. In traditional printing-writing applications, these surface treatments can be of the type commonly used on cellulosic supports. for special applications, their nature will depend on the desired properties.

Other advantages and characteristics will be better understood on reading the following examples which are nonlimiting but given by way of illustration.

EXAMPLES 1 to 14

By proceeding as indicated above in the best embodiment, reinforced thermoplastic sheets were prepared having a grammage of the order of 500 g / m ² , the quantities and the nature of the products used being given in the table VIII below, the leaves obtained in stage 1) being dried at a temperature of the order of 100-150 ° C., the leaves subjected to the treatment in stage 2) being also dried at a temperature of the order of 100- 150 ° C after said treatment.

The sheets thus obtained were then loumises & thermoplastification at 180 ° C for 3 min, then tested. The results of these tests have been recorded in table IX below, they allow the following conclusions to be drawn.

Examples 1 to 3 (prepared from powdered PVC) show the favorable influence of the increase in the content of cellulosic fibers on. physical properties, and in particular rigidity.

The presence of a plasticizing agent has a beneficial effect with regard to flexibility.

The association of glass fibers with cellulosic fibers (Examples 6-7 and 11) improves dimensional stability in the wet state.

In general, the surface treatment of stage 2) is beneficial with regard to the resistance to bending. More specifically, the sheets of Examples 7 and 11-14 do not show any breakage after repeated folding; they can be used as a basic support for the production of large width floor coverings (4 m).

All the sheets obtained have good thermoforming properties: it is therefore particularly advantageous to use them for thermoforming containers intended to contain food products such as in particular dairy products (yogurt, butter, fromage blanc, etc.) and mayonnaise .

Finally, these sheets can be shredded and then granulated to give place by extrusion, injection into plastic products reinforced with cellulose fibers.

EXAMPLES 15 and 16

By treatment in stage 2) of the sheets of Examples 8 and 9, on one side by means of a conventional pigmented layer to improve the surface uniformity, sheets are obtained having good printability properties.

NOTES

(1) The amounts of fiber are expressed in parts by weight.

(2) The quantities of powdered thermoplastic substance are expressed in parts by weight: the particle size is less than 500 μ; T1 = PVC,

T2 = polyethylene and T3 = polystyrene.

(3) The quantity of organic dispersant is expressed in% by weight relative to the weight of the powdered thermoplastic substance.

(4) The quantities of non-binding mineral filler are expressed in parts by weight per 100 parts by weight of MB.

(5) The plasticizer here is bis (2-ethylhexyl) phthalate (abbreviated as DOP); the quantities are expressed in 7o by weight relative to the weight of the powdered thermoplastic substance.

(6) The emulsifier of the plasticizer is here an arylpolyglycol ether: the quantities are expressed in% relative to the weight of the plasticizer. TABLE VIII (continued 3)

(7) The quantities of flocculating agent introduced before the binder are expressed in parts by weight per 100 parts by weight of MB.

(8) The quantities of binding agent are expressed in parts by weight per 100 parts by weight of MB.

(9) The quantities of water repellent are expressed in parts by weight per 100 parts by weight of MB.

(10) The antioxidant here is 2- (2-hydroxy-5-methyl-phenyl) -2H-benzotriazole; the quantities are expressed in% by weight relative to the weight of the powdered thermoplastic substance.

(11) The antistatic agent is here a quaternary ammonium derivative; the quantities are expressed in% by weight relative to the weight of the powdered thermoplastic substance.

(12) The quantities of auxiliary agent are expressed in parts by weight per 100 parts by weight of MB.

(13) The quantities of flocculating agent introduced after the binder are expressed in parts by weight per 100 parts by weight of MB.

(14) The quantities of lubricant (fatty acid derivative) are expressed in parts by weight per 100 parts by weight of MB.

(15) The treatment of stage 2), when it takes place, relates to the supply by size-press of a plasticizer (aqueous emulsion with 990 g / 1 of DOP containing 2% by weight of arylpolyglycol ether relative to by weight of DOP),

e

Claims

R E V EN D I CA T I ON S

1 - New sheet products, characterized in that they include:

- the constituents of a basic mixture comprising: 5 to 307. by weight of cellulose fibers,

95 to 70% by weight of a powder of thermoplastic material;

- And the elements essential for the preparation of a formable sheet by application of papermaking techniques, namely, essentially at least one organic binder and at least one flocculating agent.

2 - New products according to claim 1, characterized in that the cellulosic fibers used have been refined to a Shopper-Riegler degree of between 15 and 65.

3 - New products according to one of claims 1 and 2, characterized in that up to 30% of the cellulosic fibers used have been replaced by non-cellulosic fibers, in particular glass fibers.

4 - New products according to claim 3, characterized in that the fiber mixture consists of 14 parts by weight of cellulose fibers, 2 parts by weight of glass fibers and up to 1 part by weight of polyvinyl alcohol fibers insoluble in cold water.

5 - New products according to one of claims 1 to 4, characterized in that up to 40% by weight of the powder of thermoplastic material have been replaced by a non-binding mineral filler.

6 - New products according to one of claims 1 to 7, characterized in that the thermoplastic material is poly (vinyl chloride). 7 - New products according to one of claims 1 to 6, characterized in that they contain from 0.2 to 30 parts by dry weight per 100 parts by weight of the base mixture of at least one organic binder and 0 , 02 to 10 parts by weight, per 100 parts by weight of base mixture, of at least one flocculant. 8 - New products according to one of claims 1 to 7, characterized in that they also contain from 10 to 100% by weight, relative to the weight of the thermoplastic material, of plasticizer. 9 - Process for the preparation of new materials according to one of claims 1 to 8, characterized in that: a) in a first stage:

an aqueous suspension of a base mixture containing 5 to 30% by weight of cellulose fibers and 95 to 70% by weight of a powder of thermoplastic material is prepared,

- a mineral filler is optionally added to said suspension,

- 0.01 to 4 parts by weight are added successively, per 100 parts by weight of said base mixture, of a flocculating agent, then from 0.2 to 30 parts by weight, per 100 parts by weight of said base mixture , an organic binder, then 0.01 to 6 parts by weight, per 100 parts by weight of said base mixture, of a flocculating agent; b) then a sheet is formed by means of the suspension obtained, which is drained and dried; and c) in a second stage, the sheet obtained is subjected to at least one additional treatment.

10 - Process according to claim 9, characterized in that at the first stage at least one adjuvant is added which is conventional in stationery such as a water-repellent agent, a lubricating agent, an anti-or foam-breaking agent, a dye, a optical brightener and an antioxidant.

11 - Method according to one of claims 9 and 10, characterized in that one adds at the first stage from 10 to 100% by weight, relative to the thermoplastic material, of plasticizer.

12 - Method according to one of claims 9 and 10, characterized in that one adds in the second stage from 10 to 100% by weight, relative to the thermoplastic material, of plasticizer.