EP0961686A1

EP0961686A1 - Multilayer structure comprising a material coated with block polyamide and block hydrophilic copolymers

Info

Publication number: EP0961686A1
Application number: EP98963619A
Authority: EP
Inventors: Heike Faulhammer; Yves Aubert; Thierry Briffaud; Hermann Josef Hilgers; Didier Roumilhac
Original assignee: Elf Atochem SA
Current assignee: Arkema France SA
Priority date: 1997-12-24
Filing date: 1998-12-23
Publication date: 1999-12-08
Also published as: AU1882599A; CN1248199A; CA2282675A1; US6420045B1; WO1999033659A1; KR20000075607A; JP2001513719A

Abstract

The invention concerns a multilayer structure comprising a material coated with a block polyamide and block hydrophilic copolymer, said copolymer having a melting point less than 135 °C and preferably between 90 and 135 °C. Said structure is impermeable to liquid water and permeable to water vapour. The invention also concerns methods for preparing said block polyamide and block hydrophilic copolymers. It further concerns novel block polyamide and block polyether copolymers.

Description

MULTILAYER STRUCTURE COMPRISING A MATERIAL COVERED BY A COPOLYMER WITH POLYAMIDE BLOCKS AND HYDROPHILIC BLOCKS

The present invention relates to a multilayer structure comprising a material covered by a copolymer with polyamide blocks and hydrophilic blocks. It is, for example, a nonwoven coated with copolymers with polyamide blocks and hydrophilic blocks.

These copolymers with polyamide blocks and hydrophilic blocks have a melting temperature below 135 ° C. and are very fluid in the molten state, they consist, for example, of blocks of lauryllactam oligomers with a carboxylic acid termination and then condensed with a polyetherdiol. such as polyethylene glycol. The Applicant has discovered that nonwovens can be coated with these copolymers to obtain a breathable waterproof material, that is to say barrier to liquid water but which is permeable to water vapor.

The prior art EP 688826 has described breathable waterproof films essentially consisting of copolymers with polyamide blocks and polyether blocks which could be laminated on nonwovens directly hot to obtain adhesion. We can also stick these films on nonwovens or any other support. The glue is arranged in points, or in strips so as not to hinder breathability. We have now found that it is much simpler to cover the nonwoven with copolymers of polyamide blocks and hydrophilic blocks in fusion.

After cooling, a material is obtained having the same properties as that of the prior art, that is to say breathable waterproof film laminated or bonded to the nonwoven.

An advantage of the structure of the invention is the simplicity of manufacture by comparison with the hot-rolled or glued film. Another advantage of the invention is the stability of this structure in a humid environment while a hot rolled film or bonded to a nonwoven tends to separate from the nonwoven if the bonding or laminating has not been done. carefully.

The material may be based on cellulose such as paper, cardboard, a nonwoven of cellulose fibers or a nonwoven based on polyolefin fibers. the material can be a fabric or a nonwoven.

The fabric can be any fabric used in the textile industry, in particular for clothing such as, for example, cotton, polyamide, polyester. The nonwoven is generally based on homo or copolymer polyolefin fibers such as, for example, polyethylene, polypropylene or copolymers of ethylene and of an alkyl (meth) acrylate. The copolymers with polyamide blocks and hydrophilic blocks have a melting temperature below 135 ° C and preferably between 90 and 135 ° C. They are deposited in the molten state on the material then by cooling, the structure of the invention is obtained. The melting temperature is determined by DSC (differential scanning calorimetry). They can be deposited on the material by extrusion.

The fluidity of the copolymers must be sufficient to be able, in the molten state, to easily cover the material and form a structure which does not delaminate.

Advantageously, the inherent viscosity of the copolymers in solution is between 0.8 and 1.75. This relative viscosity is measured in 0.5% solution in metacresol using an OSTWALD viscometer.

Hydrophilic blocks are defined as products that can absorb at least 50% of their weight at equilibrium with liquid water. Advantageously, these are polyethers having a sufficient proportion of units ( ^C 2 ^H 4 ^- ° 7 ^~ PEG to make them hydrophilic.

Polymers containing polyamide blocks and polyether blocks result from the copolycondensation of polyamide blocks with reactive ends with polyether blocks with reactive ends, such as, inter alia:

1) Polyamide sequences with diamine chain ends with polyoxyalkylene sequences with dicarboxylic chain ends.

2) Polyamide sequences at the ends of dicarboxylic chains with polyoxyalkylene sequences at the ends of diamine chains obtained by cyanoethylation and hydrogenation of polyoxyalkylene alpha-omega dihydroxylated aliphatic sequences called polyetherdiols.

3) Polyamide sequences at the ends of dicarboxylic chains with polyetherdiols, the products obtained being, in this particular case, polyetheresteramides. The copolymers of the present invention are advantageously those described in point 3).

Polyamide sequences with dicarboxylic chain ends originate, for example, from the condensation of alpha-omega acids aminocarboxylic acids of lactams or of dicarboxylic acids and diamines in the presence of a dicarboxylic acid chain limiter.

According to a first preferred embodiment of the invention, the polyamide sequences result, for example, from the condensation of one or more alpha omega aminocarboxylic acids and / or of one or more lactams having from 6 to 12 carbon atoms in the presence of a diacid carboxylic having from 6 to 1 2 carbon atoms and are of low mass, that is to say Mn from 400 to 1000. As an example of alpha omega aminocarboxylic acid, mention may be made of aminoundecanoic acid and acid aminododecanoic. By way of example of dicarboxylic acid, mention may be made of adipic acid, sebacic acid and dodecanedioic acid HOOC- (CH2) i 0 "COOH.

By way of example of a lactam, mention may be made of caprolactam and lauryllactam.

Caprolactam should be avoided unless the polyamide is purified from the monomeric caprolactam which remains dissolved therein.

Polyamide sequences obtained by condensation of lauryllactam in the presence of adipic acid or dodecanedioic acid and of mass Mn 750 have a melting temperature of 1227-130 ° C.

According to a second preferred embodiment of the invention, the polyamide sequences result from the condensation of at least one alpha omega aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid. The alpha omega aminocarboxylic acid, the lactam and the dicarboxylic acid can be chosen from those mentioned above.

The diamine can be an aliphatic diamine having from 6 to 12 atoms, it can be aryl.

Examples include hexamethylenediamine, piperazine, isophorone diamine (IPD), methyl pentamethylenediamine (MPDM), bis (aminocyclohexyl) methane (BACM), bis (3-methyl-4 aminocyclohexyl) methane (BMACM). The various constituents of the polyamide block and their proportion are chosen to obtain a melting temperature below 135 ° C and advantageously between 90 and 135 ° C.

Caprolactam should be avoided unless the polyamide is purified from the caprolactam which remains dissolved therein. Mention may be made, as examples of polyamide sequences, of the following: a) 6.6 / Pip. 10/12 in which

6.6 denotes hexamethyleneadipamide units

(hexamethylenediamine condensed with adipic acid).

Pip. 10 denotes units resulting from the condensation of piperazine and sebacic acid.

1 2 designates patterns resulting from the condensation of lauryllactam.

The proportions by weight are respectively

25 to 35/20 to 30/20 to 30 / the total being 80 and advantageously 30 to 35/22 to 27/22 to 27 / the total being 80.

For example, the proportions 32/24/24 / lead to a melting temperature of 122 to 137 ° C. b) 6.6 / 6.10 / 1 1/12 in which 6 3 denotes hexamethylene diamine condensed with adipic acid

6.10 denotes hexamethylene diamine condensed with sebacic acid

1 1 denotes units resulting from the condensation of aminoundecanoic acid

1 2 designates patterns resulting from the condensation of lauryllactam.

The proportions by weight are respectively

10 to 20/1 5 to 25/10 to 20/1 5 to 25 the total being 70 and advantageously:

12 to 16/18 to 25/12 to 1 6/18 to 25 the total being 70.

For example, the proportions 14/21/14/21 / lead to a melting point of 1 1 9 to 131 ° C.

The hydrophilic blocks are polyetherdiols having a sufficient proportion of units ( ^C 2 4 ^~~ ° 7 ^~ to make them hydrophilic and advantageously at least 50% by weight.

The polyether blocks may comprise units other than those of ethylene oxide, for example propylene oxide units or

(7CH ₂ ) _r θy motifs The blocks are advantageously polyethylene glycols (PEG).

The copolymers of the invention can also comprise PPG blocks (polypropylene glycol) or PTMG blocks (polytetramethylene glycol) provided that there is a sufficient proportion of PEG blocks or blocks having a sufficient proportion of patterns ( ^C 2 ^H 4 ^~~ ° 7 ^~ so that the copolymers of the invention once transformed into film or coated on a nonwoven are waterproof breathable. Advantageously, the breathable waterproof character measured by the permeability to water vapor according to ASTM E 96 BW is greater than 1000 and preferably between 2000 and 15000 g / m ^2/24 h.

Advantageously, the polyether blocks are PEG with a mass Mn 100 to 6000 and preferably from 500 to 3000. The amount of polyether blocks represents from 10 to 40% by weight of the copolymer of the invention.

Particularly advantageous copolymers are:

¹ those having blocks of polyamide 1 2 (polylauryllactam) of mass Mn 750 and blocks of PEG of Mn 1,500 or 1,000; "those having polyamide 6.6 / Pip.10 / 1 2 blocks described above in a) and PEG blocks of mass Mn 600;

• those with polyamide 6.6 / 6.10 / 1 1/12 blocks described above in b) and PEG blocks of Mn 600.

The copolymers of the invention can be prepared by any means allowing the polyamide blocks and the polyether blocks to be attached. In practice, essentially two methods are used, one said in 2 steps, the other in one step.

The 2-step process consists first of all in preparing the polyamide blocks with carboxylic ends by condensation of the polyamide precursors in the presence of a chain-limiting dicarboxylic acid, then in a second step in adding the polyether and a catalyst. If the polyamide precursors are only lactams or alpha omega aminocarboxylic acids, a dicarboxylic acid is added. If the precursors already comprise a dicarboxylic acid, it is used in excess relative to the stoichiometry of the diamines. The reaction is usually carried out between 180 and 300 ° C, preferably 200 to 260 ° C, the pressure in the reactor is established between 5 and 30 bars, it is maintained for approximately 2 hours. The pressure is slowly reduced by putting the reactor into the atmosphere and then the excess water is distilled, for example an hour or two.

The polyamide with carboxylic acid ends having been prepared, the polyether and a catalyst are then added. We can add polyether in one or more times, the same for the catalyst. According to an advantageous form, the polyether is first added, the reaction of the OH ends of the polyether and of the COOH ends of the polyamide begins with ester bond formations and elimination of water; water is removed as much as possible from the reaction medium by distillation, then the catalyst is introduced to complete the bonding of the polyamide blocks and of the polyether blocks. This second step is carried out with stirring preferably under a vacuum of at least 5 mm Hg (650 Pa) at a temperature such that the reagents and the copolymers obtained are in the molten state. By way of example, this temperature can be between 100 and 400 ° C. and most often 200 and 300 ° C. The reaction is followed by measuring the torsional torque exerted by the molten polymer on the agitator or by measuring the electric power consumed by the agitator. The end of the reaction is determined by the value of the target torque or power. The catalyst is defined as being any product making it possible to facilitate the bonding of the polyamide blocks and of the polyether blocks by esterification. The catalyst is advantageously a derivative of a metal (M) chosen from the group formed by titanium, zirconium and hafnium.

By way of example of a derivative, mention may be made of tetraaoxides which correspond to the general formula M (OR) _ι, in which M represents titanium, zirconium or hafnium and the Rs, identical or different, denote alkyl radicals, linear or branched, having from 1 to 24 carbon atoms.

C- alkyl radicals | to C24 from which are chosen the radicals R of the tetraaoxides used as catalysts in the process according to the invention are for example such as methyl, ethyl, propyl, isopropyl, butyl, ethylhexyl, decyl, dodecyl, hexadodecyl. The preferred catalysts are the tetraaoxides for which the radicals R, identical or different, are alkyl radicals C- | à Cs- Examples of such catalysts are in particular Z _r (OC2H5) 4, Z _r (O-isoC3H7), Z _r (OC4H9) 4, Z _r (OC ₅ H _{1 1} ) ₄ , Z _r (OC ₆ H _{1 3} ) ₄ , Hf (OC ₂ H ₅ ) 4, H _f (OC ₄ H ₉ ) 4, H _f (O-isoC ₃ H ₇ ) 4.

The catalyst used in this process according to the invention may consist solely of one or more of the tetraaicoxides of formula M (OR) 4 defined above. It can also be formed by the association of one or more of these tetraaoxides with one or more alkaline or alkaline-earth alcoholates of formula (R- | O) pY in which Rj denotes a hydrocarbon residue, advantageously a C alkyl residue - | to C24, and preferably to C- | at Cs, Y represents an alkali or alkaline earth metal and p is the valence of Y. The amounts of alkali or alkaline earth alcoholate and of zirconium or hafnium tetraicoxides which are combined to constitute the mixed catalyst can vary within wide limits. However, it is preferred to use amounts of alcoholate and tetraalkoxides such that the molar proportion of alcoholate is substantially equal to the molar proportion of tetraalkoxide.

The proportion by weight of catalyst, that is to say of the tetraaicoxide (s) when the catalyst does not contain alkali or alkaline earth alcoholate or indeed of all or all of the tetraaoxide (s) and of alkaline or alkaline alcoholates earthy when the catalyst is formed by the combination of these two types of compounds, advantageously varies from 0.01 to 5% of the weight of the mixture of the polyamide dicarboxylic with the polyoxyaicoylene glycol, and is preferably between 0.05 and 2% of this weight. By way of example of other derivatives, mention may also be made of the salts of the metal (M) in particular the salts of (M) and of an organic acid and the complex salts between the oxide of (M) and / or l hydroxide of (M) and an organic acid. Advantageously, the organic acid can be formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauryac acid, acid myristic, palmitic acid, stearic acid, oleic acid, linolic acid, linolenic acid, cyclohexane carboxylic acid, phenylacetic acid, benzoic acid, salicylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid and crotonic acid. Acetic and propionic acids are particularly preferred. Advantageously M is zirconium. These salts can be called zirconyl salts. The Applicant, without being bound by this explanation, believes that these zirconium and organic acid salts or the complex salts mentioned above release ZrO ^{+ +} during the process. The product sold under the name of zirconyl acetate is used. The quantity to be used is the same as for the derivatives M (OR) 4-

This process and these catalysts are described in patents US 4,332,920, US 4,230,838, US 4,331, 786, US 4,252,920, JP 07145368A, JP 06287547A, and EP 61391 9.

The present invention also relates to this process for the preparation in two stages of copolymers with polyamide blocks and hydrophilic blocks having a melting temperature below 135 ° C. and which has been described above. in the multilayer structure, process in which the catalyst is a salt of the metal (M) chosen from the group of the salts of (M) and an organic acid and the complex salts between the oxide of (M) and / or l hydroxide of (M) and an organic acid. Advantageously (M) is zirconium. Preferably the catalyst is zirconyl acetate.

With regard to the one-step process, all the reagents used in the two-step process are mixed, that is to say the polyamide precursors, the chain-limiting dicarboxylic acid, the polyether and the catalyst. These are the same reagents and the same catalyst as in the two-step process described above. If the polyamide precursors are only lactams, it is advantageous to add a little water.

The copolymer has essentially the same polyether blocks, the same polyamide blocks, but also a small part of the various reactants which have reacted randomly which are distributed statistically along the polymer chain.

The reactor is closed and heated with stirring as in the first step of the two-step process described above. The pressure is established between 5 and 30 bars. When it no longer evolves, the reactor is placed under reduced pressure while maintaining vigorous stirring of the molten reactants. The reaction is followed as above for the two-step process.

The catalyst used in the one-step process is preferably a salt of the metal (M) and an organic acid or a complex salt between the oxide of (M) and / or the hydroxide of (M) and an acid organic. The present invention also relates to this process for the preparation in one step of copolymers with polyamide blocks and hydrophilic blocks having a melting temperature below 135 ° C. and which is described above in the multilayer structure, process in which the catalyst is a salt metal (M) chosen from the group of salts of (M) and an organic acid and complex salts between the oxide of (M) and / or the hydroxide of (M) and an organic acid. Advantageously (M) is zirconium. Preferably the catalyst is zirconyl acetate.

The present invention also relates to certain copolymers with polyamide blocks and hydrophilic blocks of the multilayer structure described above and more particularly those which do not contain units coming from caprolactam or from the corresponding amino acid.

US 5,489,667 describes polyamide block copolymers (i) produced from caprolactam, aminoundecanoic acid and reaction of hexamethylene diamine on adipic acid and PEG blocks (ii). These copolymers with a melting temperature between 90 and 130 ° C. are useful as HMA type adhesives (or hot melt adhesives), that is to say that they are deposited in the molten state on the surfaces to be bonded and then adhesion is obtained when they return to the solid state by cooling.

The Applicant has found that in the copolymers of the structures of the invention if caprolactam (or the corresponding amino acid) is used to prepare the polyamide blocks, it is very difficult to remove caprolactam (or the corresponding amino acid) which is not polymerized in the polyamide block. When the copolymer is melted to cover the material and form the multilayer structure of the invention, it gives off caprolactam vapors with an unpleasant odor. The Applicant has discovered that although the prior art still teaches the use of caprolactam (or the corresponding amino acid) for these copolymers, it was in fact not necessary to use it.

The present invention relates to copolymers with polyamide blocks and polyether blocks resulting from the chain of polyamide blocks with carboxylic ends and of polyetherdiols, these copolymers have a melting temperature between 90 and 135 ° C. and the polyamide blocks result from the condensation of one or more alpha omega amino carboxylic acids and / or one or more lactams having from 10 to 12 carbon atoms in the presence of a dicarboxylic acid having from 6 to 12 carbon atoms. These polyamide blocks have a low mass Mn, that is to say between 400 and 1000. Advantageously, the polyamide blocks result from the condensation of a polyamide precursor chosen from aminoundecanoic acid, aminododecanoic acid and lauryllactam in the presence adipic acid, azelaic, sebacic or dodecanedioic acid. The present invention relates to copolymers with polyamide blocks and polyether blocks resulting from the chain of polyamide blocks with carboxylic ends and of polyetherdiols, these copolymers have a melting temperature between 90 and 135 ° C. and the polyamide blocks result from condensation: - one or more diamines and one or more dicarboxylic acids each having 6 to 12 carbon atoms

- at least one lactam and / or an alpha omega aminocarboxylic acid having from 10 to 12 carbon atoms - at least one of the dicarboxylic acids being in excess.

In these polyamide block and polyether block copolymers, the lactam and / or the alpha omega aminocarboxylic acid is advantageously chosen from aminoundecanoic acid, aminododecanoic acid and lauryllactam.

Mention may be made, for example, of the blocks a) and b) mentioned above: a) 6.6 / Pip. 10/12 b) 6.6 / 6.10 / 1 1/12

Blocks 6.6 / 12/1 1 / 6.9 / 6.12 6.9 designates the condensation of hexamethylenediamine with azelaic acid

6.1 2 denotes the condensation of hexamethylenediamine with dodecanedioic acid.

These copolymers result from the linking of polyamide blocks with carboxylic ends with polyether diol blocks.

The polyether diol blocks are those described above, it is preferably polyethylene glycol (PEG).

These polymers deposited on the material and which form part of the multilayer structure of the invention are also useful as adhesives. It is not always desirable or possible to cover materials with the copolymers of the invention in the molten state. For example with these adhesives we can stick breathable films on leather, cotton or polyester fabrics. These are HMA type adhesives (or hot melt adhesives), that is to say that they are deposited in the molten state on the surfaces to be bonded, then adhesion is obtained when they return to the solid state. by cooling. Thus the presence of the adhesive does not reduce breathability since it is itself breathable, thanks to the PEG blocks. Whereas if we stick a breathable film on a nonwoven with a non-breathable glue depending on the density of the bonding points we greatly reduce the breathability of the whole.

The present invention also relates to hot-melt adhesives consisting of new copolymers having no caprolactam in the polyamide blocks. EXAMPLE 1 661 g of polyamide 12 dicarboxylic having an average molecular weight equal to 750 g / mol are introduced into a 6-liter reactor, prepared beforehand by polycondensation of lauryllactam in the presence of acid. adipic. Then added 838 g of dihydroxy polyoxyethylene (PEG) with a molecular weight equal to 1000 g / mol, then 1.5 g of Zr (OC4Hg) 4.

The mixture thus formed is placed under an inert atmosphere and heated until the temperature reaches 240 ° C. The reactor is then placed under reduced pressure while maintaining vigorous stirring of the melting of the reactants. The reaction is continued at 240 ° C under 1 Torr (130 Pa) for a period of 1 hour.

The product obtained has an inherent viscosity equal to 1.39 dl / g. In differential thermal analysis, it exhibits a crystalline melting peak at 133 ° C.

Example 2

451 g of amino 12 dodecanoic acid, 102 g of adipic acid and 1000 g of dihydroxy polyoxyethylene of average molecular weight equal to 1500 g / mole are introduced into a 6 liter reactor. The mixture thus formed is placed under an inert atmosphere and heated until the temperature reaches 240 ° C. while maintaining vigorous stirring as soon as the reactants have melted. It is left to react for 2 hours and then the water created is distilled. Then 4.5 g of Zr (OC4Hg) 4 are introduced into 7.5 g of CH2Cl2 and the reactor is placed under reduced pressure while maintaining stirring.

The reaction is continued at 220 ° C under 1 Torr (130 Pa) for a period of 2 hours.

The product obtained has an inherent viscosity equal to 1.41 dl / g. It presents in differential thermal analysis a crystalline melting peak at 135 ° C.

Example 3

391 g of lactam 12 are introduced into a 6 liter reactor,

158.84 g of dodecanoic acid, 35 g of water, 1500 g of dihydroxy polyoxyethylene of average molecular mass equal to 1500 g / mole and 7.8 ml of solution of zirconylacetate in water / acetic acid (0.625% filler total zirconylacetate).

The mixture thus formed is placed under an inert atmosphere and heated until the temperature reaches 270 ° C. while maintaining vigorous stirring as soon as the reactants have melted for 3 hours, then the pressure is released, which is then at 30 bars. When the atmospheric pressure is reached, the reactor is placed under pressure reduced by 1 Torr (130 Pa). The reaction is continued for a period of 2 hours. / 33659 - | 2

The product obtained has an inherent viscosity equal to 1.27 dl / g. It presents in differential thermal analysis a crystalline melting peak at 135 ° C.

EXAMPLE 4 391 g of lactam 12, 179 g of dodecanoic acid, 35 g of water, 1500 g of dihydroxy polyoxyethylene of average molecular weight equal to 1500 g / mol and 9.4 ml are introduced into a 6-liter reactor. of zirconylacetate solution in water / acetic acid (0.625% total charge of zirconylacetate). The mixture thus formed is placed under an inert atmosphere and heated until the temperature reaches 270 ° C. while maintaining vigorous stirring as soon as the reactants have melted for 3 hours, then the pressure is released, which is then at 30 bars. When the atmospheric pressure is reached, the reactor is placed under pressure reduced by 1 Torr (130 Pa). The reaction is continued for a period of 2 hours.

The product obtained has an inherent viscosity equal to 1.27 dl / g. It presents in differential thermal analysis a crystalline melting peak at 102 ° C.

Example 5 Preparation of the copolymer 6.6 / 6.10 / 12 / PEG.600 in proportion

14/14/42/30

The following monomers are introduced into an autoclave which is equipped with a stirrer: 16,800 g lauryllactam, 3,557 g sebacic acid (C10), 5,408 g adipic acid and 6,188 g hexamethylenediamine (in the form of a solution of 73.1% in l 'water).

The mixture thus formed is placed under an inert atmosphere and heated until the temperature reaches 290 ° C. while maintaining vigorous stirring as soon as the reactants have melted. For 2 hours, 290 ° C. and 25 bars of pressure are maintained (precondensation). Then the pressure is slowly reduced (1.25 h) by 25 bar to atmospheric pressure and the temperature from 290 to 245 ° C. Now we introduce a fine dispersion of 971 1 g dihydroxylated polyethylene (Mn = 600) and 70 g of a solution of zirconylacetate in water / acetic acid (0.625% total charge of zirconylacetate; pH _{so | ution} = 3.0- 3.5). The mixture obtained is placed under reduced pressure of ca. 30 mbar.

The reaction is continued for 3 hours. The product is extruded in a water bath and granulated. The product obtained has a viscosity / 33 659 13

inherent equal to 1.12 dl / g; melting temperature (optically determined): 120 - 130 ° C.

Example 6

The permeability of a film of thickness 40 composition 6/11 / 6-12 / PEG ratio 21/21/18/40 is 12000 g / m ² / 24h according to ASTM E 96 BW.

Claims

1. Multi-layer structure comprising a material covered by a copolymer with polyamide blocks and hydrophilic blocks, said copolymer having a melting temperature below 135°C and preferably between 90 and 135°C.

2. Structure according to claim 1 in which the hydrophilic blocks of the copolymer are polyethers having at least 50% by weight of units ^— < ^C 2 ^H 4 ^~ ° ^)~

3. Structure according to claim 2 in which the quantity of polyether blocks of the copolymer represents 10 to 40% by weight of the copolymer.

4. Structure according to any one of the preceding claims in which the material is paper, cardboard, a nonwoven of cellulose fibers, a nonwoven based on polyolefin fibers or a fabric chosen from cotton, polyamide or polyester.

5. Structure according to any one of the preceding claims in which the polyamide blocks of the copolymer result from the condensation of one or more alpha omega aminocarboxylic acids and/or one or more lactams having from 6 to 12 carbon atoms in the presence of a dicarboxylic acid having 6 to 12 carbon atoms, the polyamide blocks having a mass Mn 400 to 1000.

6. Structure according to any one of claims 1 to 4 in which the polyamide blocks of the copolymer result from the condensation of at least one alpha omega aminocarboxylic acid or a lactam, at least one diamine and at least one dicarboxylic acid.

7. Process for preparing copolymers of structures according to any one of the preceding claims in which (i) in a first step the polyamide blocks are prepared by condensation of the polyamide precursors in the presence of a limiting dicarboxylic acid /33659 5

chain then (ii) in a second step the polyether and a catalyst are added which is a metal salt (M) chosen from the group of salts of (M) and an organic acid and complex salts between the oxide of (M) and/or the hydroxide of (M) and an organic acid.

8. Process for preparing copolymers of structures according to any one of claims 1 to 6 in which the polyamide precursors, a chain-limiting dicarboxylic acid, the polyether and a catalyst which is a selected metal salt (M) are mixed. in the group of salts of (M) and an organic acid and complex salts between the oxide of (M) and/or the hydroxide of (M) and an organic acid.

9. Method according to claim 7 or 8 in which (M) is chosen from titanium, zirconium and hafnium.

10. Method according to claim 9 in which (M) is zirconium.

11. Process according to claim 7 or 8 in which the catalyst is zirconyl acetate

12. Copolymers with polyamide blocks and polyether blocks resulting from the sequence of polyamide blocks with carboxylic acid ends and polyether diols having a melting temperature of between 90 and 135°C in which the polyamide blocks result from the condensation of one or several alpha omega aminocarboxylic acids and/or one or more lactams having 10 to 12 carbon atoms in the presence of a dicarboxylic acid having 6 to 12 carbon atoms, and in which the mass Mn of the polyamide blocks is between 400 and 1000.

13. Copolymers with polyamide blocks and polyether blocks resulting from the sequence of polyamide blocks with carboxylic ends and polyether diols, these copolymers having a melting temperature of between 90 and 135°C and in which the polyamide blocks result from condensation:

- one or more diamines and one or more dicarboxylic acids each having 6 to 12 carbon atoms 33659 _1g

- at least one lactam and/or an alpha omega aminocarboxylic acid having 10 to 12 carbon atoms

- at least one of the dicarboxylic acids being in excess.

14. Copolymers according to claim 12 or 13 in which the lactam and/or the alpha omega aminocarboxylic acid having 10 to 12 carbon atoms is chosen from aminoundecanoic acid, aminododecanoic acid and lauryllactam.

15. Copolymers according to claim 14 having polyamide blocks 6.6/Pip.10/12 in which:

6.6 designates units resulting from the condensation of hexamethylene diamine and adipic acid.

Pip. 10 designates units resulting from the condensation of piperazine and sebacic acid.

12 designates patterns resulting from the condensation of lauryllactam.

16. Copolymers according to claim 14 having polyamide blocks 6.6/6.12/1 1/12 in which:

6.6 denotes units resulting from the condensation of hexamethylene diamine and adipic acid

6.1 2 designates units resulting from the condensation of hexamethylenediamine and dodecanedioic acid Yλ_ designates units resulting from the condensation of aminoundecanoic acid

12 designates patterns resulting from the condensation of lauryllactam.

17. Copolymers according to any one of claims 12 to

1 6 in which the polyetherdiols are PEG (polyethylene glycol).

18. Hot melt adhesive (HMA) consisting of copolymers with polyamide blocks and polyether blocks according to any one of claims 12 to 17.