MXPA06008145A - Method for production of non-woven surfaces - Google Patents

Abstract

The invention relates to a novel method for the production of non-woven surfaces, in particular, a method for the production of non-woven surfaces by the process of direct spinning of molten filaments arranged in the form of a mat. Said method makes use of a composition of thermoplastic polymers with an electrical conductivity sufficient to either avoid the build-up of electrostatic charges, or to permit the removal thereof during the spinning process.

Description

PROCEDURE FOR THE MANUFACTURING OF UNCONTROLLED SURFACES The present invention relates to a new process for the manufacture of non-woven surfaces.

It relates more particularly to a process for the manufacture of non-woven surfaces through the process for direct filament spinning, arranged in the form of a sheet. This process employs a composition based on a thermoplastic polymer that exhibits sufficient electrical conductivity to either prevent the formation of electrostatic charges or to allow its removal during the spinning process.

Non-woven surfaces are very widely used in numerous applications, such as the preparation of surface coverages, for example. These surfaces are obtained according to various methods, such as the wet process, which consists of suspending the fibers in a liquid advantageously comprising a product that makes the connection possible. These fibers are collected on a collection surface to produce a leaf that is calendered and dried to form the non-hatched surface.

Another procedure that is also used is the so-called "dry route procedure". This procedure consists of forming a sheet with cut and carded fibers formed in a network and then the sheet is treated to give cohesion. With this route - dry, it is also possible to manufacture continuous strand or filament sheets.

However, in the case of continuous strands or filaments, the most widely used process is the melt spinning process, which is known as the "direct spinning" process.

This process consists in extruding one or more polymers through one or more rows to produce several filaments that will be attenuated by pneumatic means and deposited on a collection surface to form a sheet. This sheet can be made cohesive according to various methods, such as impregnation with a resin or by thermal bonding. In this case, some filaments are manufactured from a polymer with a melting or softening point lower than that of the other filaments. Then the cohesion is obtained through a heat treatment of the leaf.

To obtain a sheet that shows good properties and good homogeneity, it is essential, first, to obtain a uniform distribution of the continuous filaments on the collection surface and, second, that the deposited filaments show homogeneous characteristics and properties.

In continuous direct spinning processes, it may be difficult to produce homogeneous continuous filaments or strands and a uniform distribution of the latter. This is because the individual filaments that come out of each row perforation are put together in a strand of multiple filaments. This convergence of the filaments is carried out pneumatically. However, as specified in US Pat. No. 4,758,134, electrostatic charges are generated in the filaments, resulting in a dispersion of the latter and preventing the procedure from proceeding correctly. The patent, to limit the damaging effect of these electrostatic charges, provides for the operation to be performed in a humid atmosphere. This solution also shows disadvantages, in particular when the polymers used are sensitive to moisture, such as, for example, polyamides.

One of the objects of the present invention is in particular to solve these disadvantages by providing the use of a composition based on thermoplastic polymers, the composition showing the electrically conductive properties that make it possible to prevent the effect of interruption of electrostatic charges.

Up to this point, the present invention provides a process for the manufacture of non-woven surfaces through the direct melt spinning of the filaments of a composition based on thermoplastic polymers., which comprises feeding the composition to a plurality of rows each comprising several spinning orifices, then feeding the obtained filaments towards a pneumatic attenuation device, and a step wherein the attenuated continuous filaments are formed into a sheet, characterized in that the composition based on thermoplastic polymers fed into the rows comprises a polymeric matrix and / or a polymeric modification additive comprising repeat units corresponding to the following general formulas: -f - ^ -f-A-R ~ A B ~ -R¿-B ~~ III where: Ri R2 / R3 and F / 'which are identical or different, represent aliphatic, cycloaliphatic or aromatic hydrocarbon chains, comprising from -2 to 18 carbon atoms. R5 represents a polyether radical with a molecular weight between 400 and 200,000, A and B represent the group CO, NH or 0; when A represents CO, B represents NH or O and vice versa, and in that the polymeric matrix comprises at least one of the repeating units I or II and at least one of the repeating units III or IV when the modification additive is absent or does not include repeat units of formula III or IV.

Advantageously, these compositions show an electrical conductivity by volume greater than or equal to 1 x -9 S / cm, preferably between 5 x 10 ~ 9 S / cm and 5 x 10"8 S / cm, however, the compositions showing a Electrical conductivity by volume different from the above range, for example, of less than 1 x 10 ~ 9 S / cm, may also be suitable for the invention.

The method for manufacturing the filaments may comprise feeding each filament to the pneumatic attenuation device or carrying the filament groups together - to form several strands of multiple filaments which are fed to the pneumatic attenuation device and then positioned on a receiving surface for form a sheet.

Since the filaments are made of a conductive polymer composition, the electrostatic charges generated on the surface of the filaments between the spinneret and the forming step on a sheet are removed very quickly. Therefore, the filaments remain parallel to one another and can be transported through the device before being formed into a sheet, without dispersion or deviation from its forward progression path. The compositions of the invention also make it possible to limit the formation of these electrostatic charges and therefore limit the effects of the dispersion of the filaments or the adhesion of the latter to the metal walls of the device. for spinning and sheet preparation. The term "conductive polymer" should be understood as meaning polymers or compositions that exhibit a structure or components that give them a higher electrical conductivity than that of unmodified polymers or compositions. However, the level of conductivity remains low and makes possible in particular the removal of the electrostatic charges that may be formed during the formation of these polymers or compositions.

The thermoplastic polymers which are suitable for the invention are advantageously ter-oplastic polymers belonging to the family of polyamides and polyesters.

Mention should be made, as suitable polymers for the process of the invention, of the conductive polymers obtained by the polymerization of the diacid and diol monomers, the diols which are composed of a mixture of alkene diols, such as glycol, butanediol or propanediol, with a polyoxyalkylene diol .

Mention should be made, as thermoplastic polyamides suitable in particular for the first embodiment of the invention, of the copolyamides obtained by the polymerization of conventional diacid, diamine or lactam monomers. However, monomers showing a specific structure are added to conventional monomers. These monomers advantageously show ether bridges in their structure, and are preferably compounds comprising a polyalkylene chain and show functional end groups which react before the functional groups of the other monomers, such as, for example, the amino functional groups, acid or hydroxyl.

These compounds, which comprise amino functional groups, are sold in particular by Huntsman under the name Jeffamines.

According to a preferred embodiment of the invention, the thermoplastic polymer is advantageously a copolyamide comprising repeat units showing polyoxyalkylene chains, making it possible to obtain an increase in the electrical conductivity of conventional polyamides, such as polyamide 6,6 or the polyamide 6.

Therefore, the thermoplastic polymer of the first embodiment of the invention is a polyamide which It collects repetition units corresponding to general formulas I or II and III or IV.

The repeating unit of formula I corresponds to the product of the polymerization reaction between a diacid selected from the group consisting of succinic acid, adipic acid, terephthalic acid, isophthalic acid, decanedioic acid, dodecanedioic acid and mixtures thereof, and a selected diamine between the group consisting of hexamethylenediamine, 2-methylpentamethylenediamine, meta-xylylenediamine and mixtures thereof. This list is not exhaustive in nature and other diacids or diamines may be used. The repeating unit of formula II corresponds to the polycondensation product of the lactams or amino acids chosen from the group consisting of caprolactam, aminoundecanoic acid, aminoduodecanoic acid and their mixtures. Similarly, this list is not exhaustive in nature and other lactams or amino acids may be used.

Advantageously, the concentration by weight of the repeating units of formula III and / or IV is between 0.5 and 5% by weight of the total repeating units or the weight of the polymer.

Conductive polyamides corresponding to the definition above are described, for example, in Patent Application WO 94/23101. These polyamides are obtained using in particular lactams or amino acids such as, for example, caprolactam, aminoundecanoic acid or aminododecanoic acid, as the main and conventional monomer.

The conductive thermoplastic polyamides can also be obtained through the polymerization of a diamine, such as hexamethylenediamine, with a diacid, such as adipic acid, in the presence or absence of a catalyst, according to the conventional polymerization processes used for the manufacture of polyamide 6,6, for example. According to the invention, the polyoxyalkylene diamine monomer is added to the polymerization medium either initially, with the diamine or diacid monomers or the salt formed by the diacid and diamine monomers, or during the polymerization process, for example, before or during the step of putting the polymer under vacuum, to obtain the desired degree of polymerization.

In this first representation, the composition comprises, as a predominant or only component, the conductive thermoplastic polymer. Of course, usual additives, such as heat stabilizers, additives to improve polymer resistance to aging may be present, such as UV stabilizers, pigments, dyes, matting agents, nucleating agents, or the like.

In a second embodiment of the invention, the composition based on a thermoplastic polymer comprises a thermoplastic polymer and a modification polymeric additive, which makes it possible to improve the electrical conductivity of the composition. This additive comprises in its structure at least one polyoxyalkylene chain. In the continuation of the text, we will refer to this additive as "conductivity additive" for greater clarity and simplicity.

According to another characteristic of this second embodiment of the invention, the concentration of the polymeric additive for modification in the composition is between 1% and 30% by weight with respect to the total weight of the composition, advantageously between 1% and 15% by weight.

According to another feature of the invention, the polymeric additive of sample modification a melt viscosity advantageously lower than that of the polymer matrix. Therefore, during the process of forming the composition, in particular during the melt spinning, the additive migrates to the surface of the strand. The properties of the surface of the strand are. modified, in particular their electrical conductivity properties.

The compositions of the second embodiment of the invention are advantageously obtained by mixing the thermoplastic polymer with the polymeric additive of modification and optionally other additives., such as those listed above. This mixture can be carried out by any conventional method. One of the preferable methods is a mixing of these components in an auger comprising two or more screws and extrusion through a die to form a belt. This tape is subsequently cut to produce granules with the desired size and the desired weight. These granules are used and se. they feed, optionally after drying, to the plant for spinning and the manufacture of non-woven surfaces.

However, without departing from the competition of the invention, it is also possible to add the polymeric additive of modification, pure or in the form of a solution Concentrated, in a host polymer (master dose), to the molten thermoplastic polymer immediately before feeding it into the spinneret to spin the non-woven.

According to a first alternative form, the polymeric additive of modification according to the invention advantageously comprises a thermoplastic structure, preferably of a nature similar to the structure of the thermoplastic polymer of the composition, and a structure comprising polyoxyalkylene chains. The thermoplastic structure can be a polyester or polyamide structure.

Mention should be made, as suitable polyesters as polymeric additives for the modification of the process of the invention, of the copolyesters obtained by the polymerization of the diacid and diol monomers, the diols being composed of a mixture of alkene diols, such as glycol, butanediol or propanediol. , with a polyoxyalkylene diol.

Mention should be made, as suitable polyamides as polymeric additives of modification of the invention, of the copolyamides which are obtained through the polymerization of conventional diacid monomers, diamine or lactam. However, monomers showing a specific structure are added to conventional monomers. These monomers advantageously show ether bridges in their structure and are preferably compounds comprising a polyoxyalkylene chain and showing terminal functional groups that react before the functional groups of the other monomers, such as, for example, amine functional groups, acid or hydroxyl.

These compounds, which comprise amine functional groups, are sold in particular by Huntsman under the name Jeffamines.

The polymeric additive of conductivity or modification is obtained by the polymerization of the monomers of the following formulas: - -R | - NH2 (VI) B- -Rj-B (HIV) where: Ri 2 and R 3 / which are identical or different, represent aliphatic, cycloaliphatic or aromatic hydrocarbon chains comprising from 2 to 18 carbon atoms. R5 represents a polyether radical with a molecular weight between 400 and 200,000, B represents the functional groups of COOH, NH2 or OH, in the presence of a monofunctional chain-limiting compound.

In order to control the melt viscosity of the additive and to limit its reactivity in the mixture with the thermoplastic polymer, the polymerization is carried out in the presence of onofunctional compounds which limit the length of the chains according to the known processes for the manufacture of polymers. Monofunctional acids, monofunctional acids and monofunctional amines should be mentioned as monofunctional compounds. Therefore, the preferable compounds are acetic acid, propionic acid and benzylamine.

Advantageously, the concentration by weight of the monomers of formula VIII in the monomer mixture is between 1 and 20% by weight of all monomers, advantageously between 1% and 10%.

The polyamides corresponding to the definition above are described, for example, in Patent Application WO 94/23101. these polyamides are obtained by using, in particular, lactams or amide acids, such as, for example, caprolacta or, aminoundecanoic acid or aminododecanoic acid, as the main and conventional monomer.

In a second alternative form of the second embodiment of the invention, the modifying or conductive polymeric additive is advantageously a compound that consists of: - at least one thermoplastic block and - at least one polyoxyalkylene block.

More specifically, this compound comprises: - at least one block of thermoplastic polymer formed by: • a macromolecular chain of star or H comprising at least one polyfunctional center and at least one branch or a segment of thermoplastic polymer connected to the center, comprising the center at least three groups functional reactive identical, and / or a macromolecular chain comprising a difunctional center and at least one segment of thermoplastic polymer connected to the center, and - at least one polyoxyalkylene block connected to at least a portion of the reactive ends of the thermoplastic polymer block.

This conductive compound is described in particular in International Patent Application WO 03/002668.

Therefore, this compound comprises a thermoplastic polymer block and at least one polyoxyalkylene block: the thermoplastic polymer block comprises: a star or H chain comprising at least one polyfunctional center and at least one branch or one segment of thermoplastic polymer connected to the center, the center comprising at least three identical reactive functional groups, and / or • a linear macromolecular chain comprising a difunctional center and at least one segment of thermoplastic polymer connected to the center, - the polyoxyalkylene block (s) are connected to at least a portion of the free ends of the thermoplastic polymer block in the following manner: at least one free end of the macromolecular star chain or H, chosen from the branch or the ends of the segmented thermoplastic polymer and the ends of the polyfunctional center, is connected with a polyoxyalkylene block, and / or at least one free end of the linear macromolecular chain, chosen from between the ends of the thermoplastic polymer segments and the ends of the center difunctional, is connected with a polyoxyalkylene block; the two free ends of the linear macromolecular chain being connected to the polyoxyalkylene blocks when the thermoplastic polymer block comprises macromolecular chains only of the linear type.

In a preferred embodiment, this compound has a star polyamide structure. This star polyamide is obtained by the copolymerization of a mixture of monomers comprising: a) a polyfunctional compound comprising minus three identical reactive functional groups chosen from the amine functional group and the carboxylic acid functional group, b) monomers of the following general formulas (Xa) and / or (Xb): c) if appropriate, monomers of the following general formula (IX): Z-R6-Z (IX) where: - Z represents a functional group identical to the reactive functional groups of the polyfunctional compound, - R 2 and Re represent aliphatic, cycloaliphatic or aromatic hydrocarbon radicals, substituted or unsubstituted, identical or different, comprising from 2 to 20 atoms of carbon and which may comprise heteroatoms, - Y is a primary amine functional group when X represents a carboxylic acid functional group, or - Y is a functional group of carboxylic acid when X represents a functional group of primary amine.

The term "carboxylic acid" is understood to mean carboxylic acids and their derivatives / such as anhydrides, acid chlorides, esters, and the like.

The term "amine" is understood to mean amines and their derivatives.

The processes for producing these star polyamides are described in Patents FR 2 743 077 and FR 2 779 730. These procedures result in the 'formation of macromolecular star chains, possibly as a mixture with linear macromolecular chains.

The star polyamide can also be obtained by melt mixing, for example in a worm mixing system, a polyamide of the type obtained by the polymerization of lactams and / or amino acids and a functional compound comprising at least three identical reactive functional groups chosen from the functional group amine or carboxylic acid. the polyamide is, for example, polyamide 6.

The preparation methods are described in EP 0 682 070 and EP 0 672 703. The polyfunctional compounds which are the monomers at the source of the star macromolecular chains or H of the first subject-matter of the invention, can be selected from among the compounds that show an arborescent or dendritic structure. They can also be selected from among the compounds represented by the formula (XI): where: • R n is an aromatic or aliphatic hydrocarbon radical, linear or cyclic, comprising at least two carbon atoms which may comprise heteroatoms, • Q is a covalent bond or an aliphatic hydrocarbon radical comprising from 1 to 6 carbon atoms. carbon, • Zi represents a primary amine radical or a carboxylic acid radical, • m is an integer between 3 and 8.

According to a specific feature of the invention, the radical Rn is either a cycloaliphatic radical, such as the tetravalent radical of cyclohexanoyl, or a 1, 1, 1-propanotril or 1,2,3-propane-trile radical.

Mention may be made, as other radicals suitable for the invention, by way of example, the substituted or unsubstituted trivalent radicals of phenyl and cyclohexanyl, the tetravalent radicals of diaminopropylmethylene with a number of methylene groups advantageously between 2 and 12, such as radical that originates from EDT? (ethylenediaminetetraacetic acid), the octavalent radicals of cyclohexanoyl or cyclohexadinonyl, and the radicals that originate from compounds resulting from the reaction of the polyols, such as glycol, pentaerythritol, sorbitol or mannitol, with acrylonitrile.

The radical Q is preferably a methylene or polymethylene radical, such as the ethylene, propylene or butylene radicals, or a polyoxyalkylene radical, such as the polyoxyethylene radical.

According to a specific representation of the invention, the number m is greater than or equal to 3 and advantageously equal to 3 or 4.

The reactive functional group of the polyfunctional compound represented by the symbol Zi is a functional group capable of forming an amide functional group.

Mention should be made, as examples of polyfunctional compounds, of 2, 2, 6, 6-tetra (β-carboxyethyl) ciciohexanone, diaminopropane-N, N, N ',' -tetraacetic acid of the following formula: or the compounds that originate from the reaction of trimethylolpropane or glycerol with propylene oxide and amination of the hydroxyl end groups. These latter compounds are sold under the trademark Jeffamines T® in Huntsman, and have the general formula: where: - Rn represents a 1, 1, 1-propanetryl radical or 1,2,3-propanetrile, - Q represents a polyoxyethylene radical.

Examples of functional compounds that may be suitable are mentioned in particular in US Pat. No. 5,346,984, in US Pat. No. 5,959,069, in Patent Application WO 96/35739 and in Patent EP 672,703.

Nitryltrialkylamines, in particular nitriloethylamine, and dialkylenetriamines, in particular diethylenetriamine, trialkylenetriamines, and tetraalkylenepentamines are particularly mentioned, with the alkylene being preferably ethylene and 4-aminoethyl-l, 8-octanediamine.

Also mentioned are the dendrimers of the formula: (R N- (CH 1) h) S! .N-. { CHa)) fN-tCHa) rt-NR, < * á2 where: R10 is a hydrogen atom or a group - (CH2) n-NR72 where: R7 is a hydrogen atom or a group - (CH2) n-NR82 where: R8 is a hydrogen atom or a group - (CH2 ) n-NR92 where: Rg is a hydrogen atom or a group - (CH2) n-NH2. where n is an integer between 22 and 6, where x is an integer between 2 and 14. n is preferably an integer equal to 3 or 4, and x is preferably an integer between 2 and 6 inclusive, preferably between 2 and 4 inclusive, in particular equal to 2. Each radical R10 may be chosen independently of the others. The radical R 10 is preferably a hydrogen atom or a group - (CH 2) n-NH 2.

Mention should be made of polyfunctional compounds which show from 3 to 10 carboxylic acid groups, preferably 3 or 4 carboxylic acid groups. Among these, preference is given to compounds which exhibit an aromatic and / or heterocyclic ring, for example benzyl, naphthyl, anthryl, biphenyl and triphenyl radicals, or heterocyclics, such as pyridine, bipyridine, pyrroline, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, pyrrolidone, indole, furan, thiophene, purine,. quinoline, phenanthrene, porphyrin, phthalocyanine and naphthalocyanine.

Particular preference is given to 3, 5,3 ', 5'-biphenyltetracarboxylic acid, to the acids derived from phthalocyanine and from naphthalocyanine, to 1,3,5,7- Naphthalene tetracarboxylic acid, to 2,4,6-pyridinetricarboxylic acid, to the acid? ) bipyridyltetracarboxylic acid, benzophenonetracarboxylic acid, 1 / 3,6,8-acridinotetracarboxylic acid, more particularly still trisodic acid and 1,2,4,5-benzenetetracarboxylic acid.

Polyfunctional compounds are also mentioned, whose center is a heterocycle that shows a point of symmetry, such as 1, 3, 5-triacinas, 1, 4-diacinas, melamine, compounds derived from 2, 3, 5,6-tetrahethylpiperazine, 1,4-piperazines or tetrathia fulvalens. Particular mention is made of 2,4,6-tri (aminocaproic acid) -1,3,5-triazine (TACT).

According to a preferable embodiment, the polyfunctional compounds are selected from 2,2,6,6-tetra (β-carboxyethyl) cyclohexanone, trimesic acid, 2,4,6-tri (aminocaproic acid) -1, 3, 5 -triazine and 4-aminoethyl-l, 8-octanediamine.

The monomer mixture at the source of the star or H macromolecular chains of the invention may comprise other compounds, such as chain-limiting agents, catalysts or additives, such as soft stabilizers, heat stabilizers or matifying agents.

In this second embodiment of the invention, the composition comprises, as essential components, a conventional thermoplastic polymer, such as a polyamide or a polyester, and a conductive additive as described above.

Mention should be made, as suitable thermoplastic polymers, of polyamide 6, polyamide 6,6, mixtures thereof and copolyamides, polyamide 12, polyethylene glycol, polypropylene glycol, polybutylene glycol, mixtures thereof and copolyesters.

As indicated above for the first embodiment, the composition may comprise other components conventionally used in the manufacture of strands or fibers, such as heat stabilizers, additives to improve the polymer's resistance to aging, such as UV stabilizers, pigments, dyes , matifying agents or nucleating agents.

Non-woven items formed from Compositions made of thermoplastic polymers are produced through a conventional process which consists in extruding the molten polymer composition through one or more rows to form a collection of filaments. These procedures are described in particular in United States Patents 3 968 307, 4 052 146, 4 406 850, 4 424 257, 4 424 -258, 4 830 904, 5 534 339, 5 783 503, 5 895 710, 6 07'4 590 and 6 207 276. The filaments are pneumatically attenuated and are deposited on a collecting surface to form a leaf. The union of the filaments of the sheet is carried out by any known means.

With the compositions of the invention, the filaments leaving the rows remain parallel to each other and can be deposited after the attenuation on the surface in a homogeneous manner and with a uniform distribution. This is because no repulsion is observed between the filaments and therefore no deviation of the direction or forward progression of the filaments is observed.

According to the invention, the filaments can show highly varied cross-sectional shapes.

It is also possible, without departing from the competition of the invention, to produce filaments made of different thermoplastic polymers, in particular two-component filaments. In this case, one of the thermoplastic polymers must be a polymer with a conductive nature according to the invention.

Other advantages and details of the invention will become apparent more clearly in the light of the examples given below, merely by way of illustration and without any limiting nature, and in light of the single figure, which represents the device for determining the Conductivity by volume of the strands.

Example 1. A polyamide PA6.6 is manufactured by adding, in a polymerization reactor, 3149 g of dry Nylon Salt (salt obtained by the stoichiometric reaction between a molecule of adipic acid and a molecule of hexamethylenediamine) to 2941 g of water with 0.21 g of pure copper acetate monohydrate powder, 7.56 g of potassium bromide powder with a purity of 99.5% by weight and 3.96 g of phenylphosphonic acid with a purity of 98% by weight.

This reaction mixture is heated to 112 ° C; The autogenous pressure of 1.2 bar absolute is subsequently regulated to this value through distillation of the water during a concentration step until a temperature of 120 ° C is obtained.

The reaction mixture is subsequently heated to 215 ° C without distillation of the water. At this temperature, the autogenous pressure reaches a value of 17.5 bar absolute and is regulated at this value by distillation of the water during a distillation step under pressure until a temperature of 230 ° C is obtained. When the temperature of the reaction mixture reaches a value of 220 ° C during this distillation step under pressure, 13.6 g of an aqueous suspension of titanium oxide at 5% by weight are added.

When the temperature of 230 ° C is reached, the pressure is reduced to atmospheric pressure during a decompression step, at the end of which the temperature of the reaction mixture reaches the value of 275 ° C.

The reaction mixture is maintained at 275 ° C in the termination step for 10 minutes; subsequently the polymer is drained in the form of a ribbon, cooled, and granulated by cutting the tapes.

The viscosity number of polymer A obtained, determined from the granules, is 140 ml / g. This is determined with the use of the ISO standard method EN 307. The amine and acid end groups are respectively measured at 43 and 76 meq / kg by potentiometry in a solvent medium of trifluoroethane / chloroform (50/50 by volume).

Example 2. A conductive polyamide according to the first embodiment of the invention is manufactured using the procedure of Example 1, further adding 3.57 g of pure adipic acid powder to the initial mixture of Nylon Salt and 77.59 g of an aqueous solution of Jeffamine ED 2003 or XTJ-502 at 70% by weight, when the temperature of the reaction mixtures reaches a value of 260 ° C during the decompression step. In addition, the duration of the finishing step is 45 minutes.

The viscosity number of the copolymer obtained, determined according to the method described in Example 1, is 139 ml / g. The terminal amine and acid groups are respectively measured at 43 and 77 meq / kg by potentiometry in a solvent medium of trifluoroethanol / chloroform.

The copolymer B obtained comprises 2% by weight of repeat units corresponding to the general formula III, that is, to the Jeffamine monomers.

Example 3. The manufacturing process is repeated in an identical manner to that of Example 2, in this case introducing 8.93 g of pure adipic acid powder and 193. 98 g of an aqueous solution of Jeffamine ED 2003 or XTJ-502 at 20% by weight.

Example 4: manufacture of a polymeric additive of modification I. This reaction is carried out in a 7.5 liter autoclave.

The viscosity number of the polymer is 125 ml / g.

The amine and acid end groups are respectively measured at 0 and 85 meq / kg by potentiometry in a solvent medium of trifluoroethanol / chloroform.

The copolymer C obtained comprises 5% by weight of repeating units corresponding to general formula III, that is, to Jeffamine monomers.

Example 4: Manufacture of a modified polymeric additive I The reaction is carried out in a 7.5 liter autoclave. 116.0 g of e-caprolactam are introduced into the reactor (9.86 mol), 57.6 g of 1, 3, 5-benzenetricarboxylic acid (0.27 mol), 1826.4 g of Jeffamine® M2070 (0.82 mol), 1.9 g of Ultranox® 236 and 3.5 g of an aqueous solution of 50% hypophosphorous acid (w / w). The autoclave is purged with dry nitrogen. The reactor is kept down with gentle rinsing with dry nitrogen.

The reaction mass is gradually heated from 20 ° C to 200 ° C. The temperature of the reaction medium is subsequently brought to 250 ° C. Then this temperature is maintained until the end of the reaction. After a stationary phase of one hour under these conditions, the system is gradually placed under vacuum until it reaches a pressure of 5 mbar and then it is kept under vacuum for an additional hour. The polymer is removed from the reactor, inside a mold.

The thermal difference analysis shows that the The polymer obtained shows a melting peak at 205 ° C.

The characterization by spherical exclusion chromatography (eluent: dimethylacetamide / O .1% LiBr) makes it possible to determine the average molecular mass per weight Mw and the average molecular mass per number Mn of the polymer (masses expressed with respect to the polystyrene standards) : Mw = 15,520 g / mol Mn = 10 960 g / mol.

The quantitative determinations of the terminal groups show a content of residual acid functional groups of 16.8 meq / kg and residual amine functional groups of 1.9 meq / kg.

The 1H NMR (Bruker 300 MHz) of a solution in a mixture of 1/1 by weight of deuterated trifluoroacetic acid and deuterated chloroform shows a residual caprolactam content of zero (undetectable) and an average degree of polycondensation of the PA6 block per branch of the star. This additive is called Additive I.

Example 5: manufacture of a composition D according to the invention. The procedure described in the Example is repeated 2. However, the pure adipic acid powder is not introduced. In addition, in place of the Jeffamine ED 2003 solution, in this case 271.2 g of a 20% by weight aqueous solution of the conductive additive I prepared according to Example 4 are introduced. The completion time is 15 minutes.

The viscosity number of the composition thus obtained and therefore of the thermoplastic polymer present in the composition, determined according to the method indicated above, is 149 ml / g. The amine and acid end groups are respectively measured at 39 and 71 meq / kg through. potentiometry in a solvent medium. of trifluoroethanol / chloroform. Composition D thus prepared comprises 2% by weight of conductive additive.

Example 6: manufacture of a composition E according to the invention. The manufacturing process is repeated in an identical manner to Example 5, in this case 678 g of a 20% aqueous solution by weight of the conductive additive I manufactured according to the Example 4 The viscosity number of the composition as well obtained and therefore of the thermoplastic polymer present in the composition, determined according to the method indicated above, is 152 ml / g. The acid and amine end groups are respectively measured at 40 and 71 meq / kg by potentiometry in a solvent medium of trifluoroethanol / chloroform. Composition E thus prepared comprises 5% by weight of conductive additive.

Example 7. The compositions of the polymers A, BC D and E manufactured in the Examples above are respectively dried and then remelted at 295 ° C and extruded through the spinneret to a range of 450 m / min and yield per weight of 430 g / h to form filaments with a count of 12 dtex and are joined together to form strands comprising - 14 filaments. The threads are attenuated in an attenuation unit according to an attenuation ratio equal to 3.5 to give, respectively, the threads registered as 7a, 7b, 7c and 7d.

The volume conductivity of these strands is measured according to the following protocol: The volumetric conductivity of the textile fibers is measured according to the measurement method "Point 2". Several strands are placed in parallel over a given length between the conductive contacts according to the scheme shown in Figure 1 attached.

The measurement is made between two steel contacts (1), separated by 20 mm. The number of to'-and-from of the strands is generally 5, i.e., 10 rows of strands in total (which corresponds exactly to 100 strands, being 1 strand composed of 10 individual strands). The diameter of the strand studied is measured in advance using a binocular magnifier, its exact length being measured with calibrators.

The measurements are made on a Keithley 617 conductivity meter with an applied voltage of 100 volts under temperature conditions of 20 ° C and 50% relative humidity conditions.

The electrical resistance by volume is obtained directly by reading the device.

The resistivity p (unit: O.cm) is deduced from the previous measurement, applying the following relationship: r A.e where: R = Electric resistance by volume (O) d = Diameter of the strand (cm) n = Total number of strands e = Distance between contacts (cm) Finally, the conductivity by volume s (unit: S. cm "1 or O-1.cm_1) is exactly the inverse of the resistivity by volume.

The volume conductivity values found for these various strands are compared in the table below: When they are spun through a process for spinning / attenuation by air suction for the manufacture of non-woven sheets, polymers B and D make possible obtaining a satisfactory behavior of the filaments in comparison with the repellent behavior of the filaments obtained by spinning the polymer A during the step of deposition of the filaments co or a sheet on a support surface, after the air attenuation device.

Example 8: manufacture of an additive II according to the invention. A polyamide 6.6 copolymer is manufactured from 240.2 g of a 64% concentrated aqueous solution by weight of a hexamethylene diammonium salt, to which are added: 6 mg of anti-foaming agent 12.945 g of Jeffamine ED 600 '(sold by Huntsman) 3,453 g of adipic acid 0.345 g of acetic acid.

The polyamide is manufactured according to the standard polymerization process comprising a step of concentrating the solution followed by a polycondensation step in an autoclave reactor with stirring, with a distillation step of about 47 min under a stationary pressure phase of 17.5 bar for which the final temperature is 250 ° C, a decompression step of approximately 36 min from 17.5 bar to 1 bar at a final temperature of 273 ° C and a completion step of approximately 20 min for which the final temperature is 272 ° C.

A copolymer based on PA '6.6 is obtained with a viscosity number of 73 ml / g.

Example 9: manufacture of an additive III according to the invention. A copolymer based on polyamide 6.6 was manufactured from 240.2 g of a 64% concentrated aqueous solution by weight of hexamethylene diammonium salt to which were added: 5 mg of antifoaming agent 0.6962 g of hexamethylenediamine ( water at 32.4% by weight) 0.9216 g of adipic acid 0.345 g of 100% acetic acid.

The polyamide was manufactured according to the following procedure in a stirred autoclave reactor: a step of concentrating the solution followed by a polycondensation step, with a distillation step of approximately 47 min under a stationary phase at a pressure of 17.5 bar for which the final temperature is 250 ° C. Polymerization is continued through a decompression step from 17.5 bar to 1 bar, which is interrupted at 10 bar to introduce 18.5 g of a 70% aqueous solution of Jeffamine ED 2003 (sold by Huntsman); the temperature of the dough is maintained at 260 ° C. After this addition, decompression is carried to completion, the decompression step lasts approximately 50 minutes, the final temperature is 272 ° C. The termination step lasts approximately 0 min, the final temperature is 272.4 ° C.

A copolymer based on AP 6,6 with a viscosity number of 72 ml / g is obtained.

Example 10. Tests were performed on the manufacture of the fibers or strands using the additive-free polymer A of Example 1 according to the invention and with different concentrations of the additives II and III described in Examples 8 and 9, as indicated in Table 1 below. In these examples, additive II or III is added to polymer A in a single screw extruder and is extruded in the form of a ribbon to form granules by cutting the tapes, according to the known techniques.

The compositions of the polymers thus obtained were respectively dried, then remelted at 295 ° C and extruded through a row comprising 34 perforations with a diameter of 0.23 mm. The range of the composition in the perforations of the row is 19.4 m / min. The filaments are cooled at the exit of the row with a fan of cold air. The filaments are sucked into a suction system composed of an ejection gun commonly used in spinning processes. The filaments are discharged from this gun at a range of 4000 m / min. The filaments are subjected to an attenuation ratio of approximately 200.

To monitor and determine if the filaments coming out of the gun are electrostatically charged, the filament stream is directed vertically on the surface of a target inclined at approximately 45 ° with respect to the vertical. The adhesion of the filaments to the surface of the lens is an indication of the presence of electrostatic charges.

The electrostatic field present near the stream of filaments coming out of the gun is also determine by positioning a static meter (device sold under the name Static Meter Model 212, by Electro-Tech Systems) approximately 3 cm (1 inch) from the axis of the filament stream. This device is either grounded or not grounded. The measurements are made in both configurations.

The absence of electrostatic charges is reflected by an electrostatic field in the vicinity of zero.

The results obtained with the compositions of the invention and an additive-free polyamide are shown in the table below: In addition, no adhesion was observed to the metal walls or to the surface of the lens for the tests of the invention, in contrast to the comparative test 10A.

Claims (15)

1. Process for the manufacture of non-woven surfaces by direct melt spinning of filaments of a composition based on thermoplastic polymers which comprises feeding the composition to a plurality of rows, each comprising several spinning holes, feeding the filaments to a pneumatic attenuation and a stage in which the filaments obtained are formed into a sheet, characterized in that the composition based on thermoplastic polymers comprises a polymeric matrix and / or a polymeric additive of modification comprising repeat units corresponding to the following general formulas : II R- 1 fi 11- £ H O O r-R -?! - t- ~ | ~ A ~ RrA- B- -Rr-8-} - Ül ~ ~ B ~~ R ^ -A B - Rj- B- A- Rg ~ -] ~ IV where: R 1 R

2, R 3 and R 4, which are identical or different, represent aliphatic hydrocarbon chains, cycloaliphatic or aromatic, comprising from 2 to 18 carbon atoms; R 5 represents a polyether radical with a molecular weight of between 400 and 200,000; A and B represent the group CO, NH or O; when A represents CO, B represents NH or O and vice versa; and wherein the polymeric matrix comprises at least one of the repeating units I or II and at least one of the repeating units III or IV when the modifying additive is absent or does not comprise repeat units of the formula III or IV. Method according to claim 1, characterized in that the polymeric additive of modification is present in the composition in a concentration by weight of between 1% and 30% of the total composition.

3. Method according to claim 2, characterized in that the polymeric additive of modification is present in the composition at a concentration by weight of between 1% and 15% of the total composition.

Method according to one of claims 1 to 3, characterized in that the polymeric additive of modification is obtained through the polymerization of the monomers of the following formulas: Hg -Rf-NH, (vi) B--? -B (HIV) wherein: Ri, R2 and R3, which are identical or different, represent aliphatic, cycloaliphatic or aromatic hydrocarbon chains comprising from 2 to 18 carbon atoms; R 5 represents a polyether radical with a molecular weight of between 400 and 200,000; B represents the functional groups of COOH, NH2 or OH; in the presence of a monofunctional compound that limits the chain.

5. Process according to claim 4, characterized in that the chain-limiting agent is selected from the group consisting of monofunctional acids and monofunctional amines.

6. Process according to claim 5, characterized in that the monofunctional compounds are chosen from the group consisting of acetic acid, propionic acid and benzylamine.

Method according to one of claims 4 to 6, characterized in that the monomer of the formula VIII is present in a concentration by weight of between 1% and 20% in the monomer mixture of the formulas V and / or VI and / or VII and monomers VIII.

8. Process according to one of claims 1 to 3, characterized in that the polymeric additive of modification is composed of: - at least one thermoplastic block; and - at least one polyoxyalkylene block. Method according to one of claims 1 to 3 and 8, characterized in that the polymeric additive of modification comprises: - at least one block of thermoplastic polymer formed by: a macromolecular star chain or H comprising at least one center polyfunctional and at least one branch or segment of thermoplastic polymer connected to the center, the center comprising at least three identical reactive functional groups, - and / or a linear macromolecular chain comprising a difunctional center and at least one segment of thermoplastic polymer connected with the center, and - at least one polyoxyalkylene block connected with at least a portion of the reactive ends of the thermoplastic polymer block. 10. Process according to claim 9, characterized in that the bond between the thermoplastic polymers is: - at least one free end of the macromolecular star chain or H, chosen from the thermoplastic polymer branch or the ends of the segment and the ends of the polyfunctional center, is connected with a poly (alkylene oxide) block, and / or - at least one free end of the linear macromolecular chain, chosen between the ends of the thermoplastic polymer segment and the ends of the difunctional center, is connected with a block of poly (ethylene oxide). alkylene); the two free ends of the linear macromolecular chain being connected to the poly (alkylene oxide) blocks when the thermoplastic polymer block comprises only macromolecular chains of the linear type. Method according to claim 10, characterized in that the star macromolecular chain is a star polyamide obtained by the copolymerization of a mixture of monomers comprising: - a polyfunctional compound comprising at least three identical reactive functional groups selected from among the amine functional group and the carboxylic acid functional group, - monomers of the following general formulas (Xa) and / or (Xb): - if appropriate, monomers of the following general formula (IX): Z-R6-Z (IX) wherein: Z represents a functional group identical to the reactive functional groups of the polyfunctional compound; R 12 and Rβ represent substituted or unsubstituted, identical or different hydrocarbon-aliphatic, cycloaliphatic or aromatic radicals, comprising from 2 to 20 carbon atoms and which may comprise heteroatoms; Y is a primary amine functional group when X represents a carboxylic acid functional group; or Y is a carboxylic acid functional group when X represents a primary amine functional group. Method according to one of the preceding claims, characterized in that the concentration by weight of the repeating units of the formula. III and / or IV, when the polymer matrix comprises them, is between 0.5 and 5% by weight of the matrix. Method according to one of the preceding claims, characterized in that the repeating units of formula III and / or IV originating from the reaction between a polyoxyalkylene monomer comprising two terminal reactive functional groups with a monomer of diacid or a lactam. Method according to one of the preceding claims, characterized in that the repeating unit of formula I is obtained by the reaction between a diacid selected from the group consisting of succinic acid, adipic acid, terephthalic acid, isophthalic acid, dodecanedioic acid and mixtures thereof and a diamine selected from the group consisting of hexamethylenediamine, 2-methylpentamethylenediamine and meta-xylylenediamine. 15. Procedure of. according to one of the preceding claims, characterized in that the repeating unit of formula II is obtained by the polycondensation of the lactams or amino acids chosen from the group consisting of caprolactam, aminoundecanoic acid and aminododecanoic acid. SUMMARY The invention relates to a new method for the production of non-woven surfaces, in particular to a method for the production of non-woven surfaces through the process of direct spinning of molten filaments arranged in the form of a mat. The method makes use of a composition of thermoplastic polymers with a sufficient electrical conductivity to avoid the accumulation of electrostatic charges, or to allow the removal thereof during the spinning process.