Stock material or miscellaneous articles – Composite – Of polyamide
Reexamination Certificate
2000-06-23
2002-07-16
Seidleck, James J. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyamide
C428S474900, C428S475200, C428S476300, C428S479300, C428S479600, C428S349000, C528S310000, C528S322000, C528S332000, C528S335000, C528S336000
Reexamination Certificate
active
06420045
ABSTRACT:
The present invention relates to a multilayer structure comprising a material covered with a copolymer having polyamide blocks and hydrophilic blocks. It is, for example, a nonwoven coated with copolymers having polyamide blocks and hydrophilic blocks.
These copolymers having polyamide blocks and hydrophilic blocks have a melting point of less than 135° C. and are very fluid in the melt. They consist, for example, of blocks of carboxylic-acid-terminated lauryllactam oligomers which are then condensed with a polyether diol such as polyethylene glycol. The Applicant has discovered that nonwovens could be coated with these copolymers in order to obtain an impermeable-breathable material, i.e. one which is a barrier to liquid water but which is permeable to water vapour.
The prior art EP 688826 has described impermeable-breathable films essentially consisting of copolymers having polyamide blocks and polyether blocks which could be hot laminated directly to nonwovens in order to obtain adhesion. These films may also be adhesively bonded to nonwovens or any other substrate. The adhesive is placed in spots, or in stripes in order not to impair the breathability. It has now been discovered that it is much simpler to cover the nonwoven with copolymers having polyamide blocks and hydrophilic blocks in the melt.
After cooling, a material is obtained which has the same properties as that of the prior art, that is to say of the impermeable-breathable film laminated or adhesively bonded to the nonwoven.
An advantage of the structure of the invention is the simplicity of manufacture compared with the hot-laminated or adhesively bonded film. Another advantage of the invention is the stability of this structure in a wet environment, while a film hot-laminated or adhesively bonded to a nonwoven has a tendency to separate from the nonwoven if the adhesive bonding or the laminating has not been carried out carefully.
The material may be based on cellulose, such as paper, board, a nonwoven consisting of cellulose fibres or a nonwoven based on polyolefin fibres.
The material may be a woven or a nonwoven.
The woven may be any woven used in the textile industry, particularly for clothing, for example cotton, polyamide or polyester. The nonwoven is generally based on fibres of a homopolymer or copolymer polyolefin, such as, for example, polyethylene, polypropylene or ethylene-alkyl (meth)acrylate copolymers .
The copolymers having polyamide blocks and hydrophilic blocks have a melting point of less than 135° C. and Preferably between 90 and 135° C. They are melt-deposited on the material and then, by cooling, the structure of the invention is obtained. The melting point is determined by DSC, (Differential Scanning Calorimetry). They may be deposited on the material by extrusion.
The fluidity of the copolymers must be sufficient to be able, in the melt, 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 as a 0.5% solution in metacresol using an Ostwald viscometer.
The hydrophilic blocks are defined as products that can absorb at least 50% of their weight in equilibrium with liquid water.
Advantageously, these are polyethers having a sufficient proportion of PEG units —(C
2
H
4
—O)— in order to make them hydrophilic.
The polymers having polyamide blocks and Polyether blocks result from the copolycondensation of polyamide blocks having reactive end groups with polyether blocks having reactive end groups, such as, inter alia:
1) Polyamide blocks having diamine chain ends with Polyoxyalkylene blocks having dicarboxylic chain ends;
2) Polyamide blocks having dicarboxylic chain ends with Polyoxyalkylene blocks having diamine chain ends, obtained by cyanoethylation and hydrogenation of aliphatic dihydroxylated alpha,omega-polyoxyalkylene blocks, called polyether diols;
3) Polyamide blocks having dicarboxylic chain ends with polyether diols, the products obtained being, in this special case, Polyetheresteramides.
The copolymers ofthe present invention are those advantageously described in point
3).
The polyamide blocks having dicarboxylic chain ends derive, for example, from the condensation of alpha,omega-aminocarboxylic acids of lactams or of dicarboxylic acids with diamines in the presence of a chain-limiting dicarboxylic acid.
According to a first preferred embodiment of the invention, the polyamide blocks 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 dicarboxylic acid having from 6 to 12 carbon atoms and have a low mass, i.e. an {overscore (M)}
n
of 400 to 1000. By way of example, of an alpha, omega-aminocarboxylic acid, mention may be made of aminoundecanoic and aminododecanoic acid. By way of example of a dicarboxylic acid, mention may be made of adipic acid, sebacic acid and dodecanedioic acid HOOC—(CH
2
)
10
—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 of the caprolactam monomer which remains dissolved in it.
Polyamide blocks obtained by the condensation of lauryllactam in the presence of adipic acid or of dodecanedioic acid and a mass {overscore (M)}n of 750 have a melting point of 127-130° C.
According to a second preferred embodiment of the invention, the polyamide blocks 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 may be chosen from those mentioned above.
The diamine may be an aliphatic diamine having from 6 to 12 carbon atoms, it may be an aryl diamine.
By way of examples, mention may made of 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 in order to obtain a melting point of less than 135° C. and advantageously of between 90 and 135° C.
Caprolactam should be avoided unless the polyamide is purified of the caprolactam which remains dissolved in it.
By way of examples of polyamide blocks, mention may be made of the following:
a) 6,6/Pip. 10/12
in which
6,6 denotes hexamethyleneadipamide (hexamethylenediamine condensed with adipic acid) units;
Pip. 10 denotes units resulting from the condensation of piperazine with sebacic acid;
12 denotes units 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 result in a melting point of 122 to 137° C.
b) 6,6/6,10/11/12
in which
6,6 denotes hexamethylenediamine condensed with adipic acid;
6,10 denotes hexamethylenediamine condensed with sebacic acid;
11 denotes units resulting from the condensation of aminoundecanoic acid;
12 denotes units resulting from the condensation of lauryllactam.
The proportions by weight are respectively:
10 to 20/15 to 25/10 to 20/15 to 25, the total being 70, and advantageously:
12 to 16/18 to 25/12 to 16/18 to 25, the total being 70.
For example, the proportions 14/21/14/21/result in a melting point of 119 to 131° C.
The hydrophilic blocks are polyether diols having a proportion of —(C
2
H
4
—O)— units sufficient to make them hydrophilic and advantageously at least 50% by weight.
The polyether blocks may include units other than those of ethylene oxide, for example propylene oxide units or (—(CH
2
)
4
—O)— units.
The blocks are advantageously polyethylene glycol (PEG) blocks.
The copolymers of the invention may also include PPG (polypropylene glycol) blocks or PTMG (polytetramethylene glycol) blocks provided that there is a sufficient proportion of PEG
Aubert Yves
Briffaud Thierry
Faulhammer Heike
Hilgers Hermann Josef
Roumilhac Didier
Atofina
Bissett Melanie
Millen White Zelano & Branigan P.C.
Seidleck James J.
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