DE2261619A1 - NON-WOVEN PRODUCTS WITH THERMAL RESISTANT BINDING AGENT - Google Patents

Description

Dr. F. Zumstein Sr. - Dr. E. Assmann Dr. R. Koenlgsberger - Dlpl.-Phys. R. Holzbauer - Dr. F. Zumstein Jun.

PATENT LAWYERS

TELEPHONE: COLLECTIVE NO. 225341 TELEGRAMS: ZUMPAT CHECK ACCOUNT: MUNICH 91139

BANK ACCOUNT: BANK H. HOUSES

8 MUNICH 2,

SC 4-006

RHONE-POULENC S.A., Paris / France

Non-woven products with a heat-resistant binder

The present invention relates to new nonwoven products in which the binder is a heat resistant one Polymer is.

The term "nonwoven products" means in its broad sense textile products made by chemical or mechanical bonding of fibers are obtained without a spinning, weaving or weaving operation. In a more limited one The term "nonwoven products" is reserved for products made by binding fibers obtained by means of a natural or synthetic binder .: The term "non-woven products" is used used here in this second sense.

There is an extensive literature relating to the manufacture of nonwoven articles using a polymeric Binder present, these publications referring to the nature of the fibers used, the nature of the binder or also processes and devices that enable the manufacture of non-woven products. Depending on the Plant fibers are used for the intended applications

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(Wood, flax, jute, hemp, sisal, coconut, kapok, ramie), Filaments of animal origin (wool, goat hair ^ camel hair, Rabbit hair), fibers made of artificial polymers (Cßllulaseeacetat) or synthetic polymers (polyester, polyamide, polyacrylonitrile) or glass fibers or asbestos fibers. There are also natural binders (cellulose, natural rubber) or synthetic binders (butadiene-acrylonitrile copolymers, Polyvinyl acetate, acrylic or methacrylic copolymers, Polyvinyl chloride, polychloroprene, melamine-formaldehyde resins, Urea-formaldehyde resins, epoxy resins) are used.

The present invention relates to a new category of nonwoven products, particularly for applications which require a high level of heat resistance.

The products according to the invention are in the form of a fleece bound to one another by a synthetic polymer Fibers and are characterized in that

a) the material forming the fibers is infusible or a * - ..; Has a softening point above 180 ^° C,

b) the binder is a polyamide-imide,

c) the weight ratio of the binder makes up 5 to 150% of the weight of the dried fibers used.

The poly used as a binder in the invention

amid-imides can be defined as products that have a. Number of groupings in the formula

-NH-QN "IR-CO- \ ,. _: . (I). '

have, in which the symbol Q is a divalent residue with means at least one benzene ring and the symbol H represents a trivalent aromatic best.

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As examples of residues represented by the symbol Q. can be »one of the m-phenylene, p-phenylene and p ^ p'-diphenylene radicals or radicals of the formula

in which the symbol T is a divalent atom or a divalent Group, such as -0-, -CHp-, -C (CH_) p-, -SOvj- or; -N = N-, represents, call.

As examples of radicals represented by the symbol R, one can use the "trivalent radicals of the formulas

to name.

The polyamide-imides described above can be used according to various techniques such as those in British Patents 570,858 and 1,181,446, U.S. Patent 3,260,691 and French Patent Nos. 1,386,617, 1,473,600, 1,501,198, 1,559,357 and 1 576 844.

Among these polyamide-imides are particularly those made of trimellitic anhydride and a difunctional derivative of the formula

X-Q-X (III)

in which the symbol X is an NCO group or a group of the formula -NHCOR _x . means, where the symbol iL can represent an alkyl radical having 1 to 6 carbon atoms or a phenyl or methylphenyl radical, can be obtained.

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According to the invention, preference is given to using polyamide-imides which have a reduced viscosity between 30 and 180 cur / g (measured in solution with 0.5% in N-methylpyrrolidone).

Those from the reaction of trimellitic anhydride with 4,4'-diisocyanatodiphenylmethane or 4,4'-diisocyanatodiphenyl ether Polytrimellitamide imides derived from these are particularly suitable for the production of the nonwoven fabrics according to the invention Products.

The fibers used in the invention can be selected from various fibers such as those given above Possess properties. In particular, it can be inorganic fibers, such as glass fibers, carbon fibers, Aluminum and zirconium oxide fibers, asbestos fibers, Boron fibers and metallic fibers, for example copper fibers and steel fibers, act. It can also be fibers, derived from organic polymers. As examples of such polymers, one can use the polyesters of the polyethylene glycol terephthalate type, the Polyamides obtained by polycondensation of caprolactam or by reaction of adipic acid with hexamethylenediamine are obtained, polyacrylonitrile, fluorinated polymers such as polytetrafluoroethylene, or the Name copolymers of tetrafluoroethylene and hexafluoropropylene. Other examples of polymers that are in the shape of fibers can be brought, the polymers are of the polyamide-imide type, such as, for example, the polytrimellitamide imides or the polyamides, which come from completely aromatic substances.

The above-mentioned fiber-forming polyamide-imides can are of the same type as the polymers used as binders in the invention. It can therefore be polymers act, which have a number of groupings of the formula I essentially.

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It can also be polymers other than the groupings of the formula I groupings of the formula

-NH-Q-NH-CO-Z-GO-: (IV) and / or groupings of the formula

-HH-Q-NH-GO -

have, in which the symbol Q has the meaning given above, the symbol Z a divalent aliphatic, cycloaliphatic or aromatic radical, M is an alkali or alkaline earth metal ion and η is 1 or 2.

As examples of residues represented by the symbol Z, one can use arylene radicals, such as, for example, the alkylene radicals with 2 to 12 carbon atoms represented by the symbol Q, such as ethylene, trimethylene, tetramethylene, hexamethylene and octamethylene radicals, and cycloalkylene radicals with 5 or 6 carbon atoms in the ring, such as Cyclopentylene and cyclohexylene radicals, name.

The fully aromatic polyamides can be used as products defined by repeating units of the formula

R _? ROO. '....- ■ I ² I ² / I Il ·

-N-Q-N-- C-Q-C- (Vl)

consist in which the different symbols Q that are equal to or can be different from one another, have the meanings given above and the symbols Rp are identical to or from one another can be different, each represent a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms.

It should be noted that in the preparation of the invention Produce a single type of fiber or against it

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can use a mixture of fibers. These fibers have in the ' generally a length between 0.2 and 50 well and a titer, expressed in decitex, between 0.5 and 20.

The invention also relates to a method for producing the nonwoven products described above.

The procedure essentially consists of:

a) to form a dry fiber fleece,

b) the fleece obtained with a polyamide-imide solution get in touch with} and

c) drying the product thus obtained.

The fiber fleece can be obtained in a dry way or in a wet way, also called a paper route.

In the following the term "fleece" is used to denote the Textile part of the products according to the invention, considered in the final stage of its manufacture, reserved, this fleece can be obtained even from several layers of fibers called "pile".

In particular, according to the dry technique, the fleece can be made up of parallel, crossed or arbitrarily arranged Fibers exist. In general, the webs with parallel fibers are obtained by carding. Considering the great The lightness of the pile obtained by this technique can be several piles on top of each other before using the binder arrange to get the desired thickness. The nonwovens with crossed fibers are generally made by laying obtained from piles with parallel fibers, these fibers being oriented in different directions according to the piles: In general, the angle of intersection of the webs will be a function of the ultimate use of the nonwoven product chosen. The fleece obtained in this way can be used as such

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be turned. However, it is generally desirable to use this nonwoven fabric to press to solidify it.

The fiber fleece can also consist of randomly arranged fibers exist. In general, the usual technique is to remove the fibers previously opened by mechanical means to spray onto a screen compressor under the action of a jet of air.

Other techniques can be used to keep nonwovens dry. So you can when the fiber-forming Material suitable for producing nonwovens directly at the outlet of the spinneret. The interweaving of the fibers can after various techniques currently known and generally referred to as "spun-bonded" are designated.

It should be noted that the processes briefly cited above do not limit the invention to those obtained according to this information To represent fleeces. In particular, the mechanical treatments that are generally involved in manufacture made of nonwovens, such as needling with its various variants, within the framework of Invention.

Furthermore, the production of nonwovens on the Extending paper path on each nonwoven fabric by removing water from a fiber dispersion through a porous support is preserved. The working techniques, such as the conditions related to agitation and fiber dispersion, the production speed of the fiber fleece or the operating material used in this process known. '·. ■

The cohesion of the nonwoven fabric obtained as described above is based in principle only on the interlacing of the fibers, and the use of the binder should only be carried out in the following stage

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of the procedure. It should be noted, however, that it is possible or is sometimes desired, especially in the case of fibers, that are difficult to anchor with each other, the fibers in the stadium to bind something in the manufacture of the fleece. The use of such a supplementary binder is particularly important In the case of production by the wet route, this is made easier because this supplementary binder is incorporated into the fiber dispersion can be. Since this binder is only used to enable handling of the fleece, the proportion of the quantity this binding agent is low (for example 5 to 30%, based on the weight of the fibers), and the main characteristic of this product is in the solvents of polyamide-imide to be insoluble. An example of a particularly recommended binder is polyvinyl alcohol.

Regardless of how the fiber fleece is manufactured, it should be at the time of its being brought into contact with the Binder dry leg. If the fleece was produced by a wet method, it is therefore necessary to remove the water. In general, the fleece is heated for 5 minutes to 1 hour at a temperature between 50 and 100 ° C., if necessary under partial vacuum.

The polyamide-imide is used in the form of a solution. The solvents used are generally polar organic solvents, such as, for example, N-methylpyrrolidone- (2), Dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylcaprolactarn, a cresol, xylene or a mixture this solvent.

The concentration of the polyamide-imide solutions is generally between 0.1 and 30% and preferably between 0.5 and 10 %.

The treatment of the fiber fleece with the binder solution can done in different ways. So you can immerse the fleece in the binder solution. You can also put the fleece on

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Cover one or both sides and repeat this operation one or more times. You can also use the binder solution spray onto the fleece, for example by means of a spray gun with compressed air. It should be noted that it is are conventional techniques and the use of equivalent techniques is within the scope of the invention.

The amount of polyamide-imide applied to the non-woven fabric (expressed as the weight of the dry polymer per m Surface of the fleece) is generally between 1 and 50 g. An amount between 1.5 and 20 g / m '"' enables products with excellent properties.

After the nonwoven has been treated with the binder, the solvent is removed. It is beneficial in a first Step to press the fleece. Then you can Let the solvent evaporate. However, it is desirable, especially if the solvent of the binder has the Fleece-forming fibers can loosen or swell, which can be the case if the fibers are made of the same polymer how the binder originated, the removal of the solvent to accelerate, for example by applying a vacuum and / or heating to a temperature between 100 and 250 ° C, for a period of time which, depending on the temperature, can be 5 minutes to 4 hours.

The nonwoven products according to the invention are distinguished by high "mechanical properties both at room temperature and at high temperature, for example 200 ^° C."

They can be used in various industrial applications, such as in particular for the production of filters for smoke dedusting or for the continuous regeneration of motor oils, as materials for insulation in electrical applications and as catalyst carriers * ^L

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The following examples serve to further illustrate the invention.

Examples 1 to 3

a) With manual stirring in 500 cm * of water, the 2.5 6 of a surface-active agent (sodium salt of a secondary alkyl sulfate), which is commercially available under the trade name Teepol contains 1.8 g of aromatic polyamide fibers sold by the Du Pont de Nemours company under the Trade name "NOMEX" are commercially available and are derived from a polymer that has a number of groupings the formula

NH-C

having. The average length of the fibers is 6 mm and their titer 2.2 a>, ex.

This dispersion is poured into a paper machine (Formette Frank, equipped with a sieve with a square mesh of 120 χ 240 μ, which is covered with a cotton lining) introduced, the agitated mixture being brought to about 6 1 by adding water. You remove the water through Application of a vacuum (reduced pressure to 100 mm Hg). The pile obtained is still wet from between two foils Polyfluoroethylene propylene (FEP) brought one of which in a degree of about a perforation with a diameter

of 0.9 mm / cm surface is perforated. The whole thing will then Dried 9 minutes at 93 ° C under partial vacuum (10 mm Hg). After drying, the whole thing is removed non-perforated FEP film.

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b) The non-bonded pile produced in this way is impregnated (weight: approx
works in the following way:

which Flors (weight: about 50 g / m) by placing in the

Inside a suction filter with an inner diameter of 240 mm, which is placed on a vacuum flask, one brings successively a sheet of filter paper and then that of the perforated FEP film, non-bonded pile worn in this way indicates that the perforated FEP film is in contact with the filter paper. You then impregnate with about 30 cmr a solution of the polyamide-imide resin defined below and reduces the excess of the solution by applying a vacuum (pressure reduced to 100 mm Hg) during 5 minutes-

The supported yet by the FEP film web obtained is dried in a ventilated oven at 200 ⁰ G for 4 minutes. The FEP film is removed and the fleece is heated again at 250 ° C. for 15 minutes.

The polyamide-imide resin is produced by condensing trimellitic anhydride with 4,4'-diisocyanatodiphenyl ether with a molar excess of diisocyanate of 5 % . The resin has a reduced viscosity of 48 cnr / g, measured in a 0.5% solution in N-methylpyrrolidone. It is used in the form of a solution in the same solvent with the concentrations given below.

In the table below are the concentrations of the impregnation solution and the properties of the ones obtained Products specified. The tensile strength (hereinafter referred to as tensile strength and the elongation at break are determined in accordance with the AFNOR Q 05004 standard. The tensile strength is in kg for a Expressed width of 5 cm.

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Table I.

at Dry weight Up
brought it
Bandage
middle tensile strenght at 200 ^° C at 20 Tear length at 200 ^° C Elongation at break at % 20 ⁰ C > at S. 200 ⁰ C game extract
of
Bads * Ender
things
nis g / m ² at 2O ⁰ C kg m ⁰ C m 6, 7th 6th g / m ² 8.3 kg 11.80 6 340 4060 6, 4th 7th ,8th (D 3.5 58.1 6.1 18.42 10.07 6 700 3 600 2, 8th 3, OO
ro
^ 2 3.5 55.9 2.8 18.73 4.55 2,775 1 707 9 ° 3
NJ -> 53.3 7.40

* In g resin for 100 g solution.

Examples 4-8

a) It is dispersed in 50 cnr water with manual stirring 0.180 g of a completely saponified polyvinyl alcohol with an average grain size of about 120 microns.

In addition, the 2.5 g of a surface-active agent (sodium salt -a secondary alkyl sulfate), which is commercially available under the Tradename Teepol, contains 1.8 g of the aromatic polyamide fibers used in Examples 1 to 3.

The two dispersions are then mixed and then introduced into a paper machine (Formette FRANCK, equipped with a sieve with rectangular mesh of 120 240 microns), with the agitated mixture up about 6 1 is brought by adding water. The water is removed by applying a vacuum (reduced to 100 mm Hg Pressure). The resulting pile is dried at 93 ° C. for 9 minutes under partial vacuum (10 mm Hg).

'b) The pile produced as indicated above is then im Full bath in the solution used in Examples 1 to 3 Impregnated polyamide-imide resin and then passed between pressed the rollers of a hand wringer.

This wringing machine consists of two rubber waltzes that are on mounted parallel axes and covered with a polyethylene glycol terephthalate film are coated. Each roller has a length of 30 cm and a diameter of 45 mm. You set the distance so that there is a passage between the rollers of about 10/1 OQ mm remains.

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c) The nonwoven fabric obtained is dried in a ventilated oven at 25O ⁰ C. To avoid sticking to the carrier
a film made of polyfluoroethylene propylene (FEP) is arranged between this and the fleece.

After 4 minutes at 250 ° C., the fleece is removed from the FEP film and then continues drying for 15 minutes.

The properties of the unwoven product are determined. These results are shown in Table II below.

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Examples 9-15

The experiments of Examples 4 to 8 are repeated, using a solution of a polyamide imide resin obtained by condensation of trimellitic anhydride with 4,4'-diisocyanatodiphenylmethane with a 3% molar excess of diisocyanate in a mixture of N- ^M and ethylpyrrolidone as the impregnation bath Xylene used in a weight ratio of 80:20.

The resin used has a reduced viscosity of 47 cnr / g (measured as before).

The properties of the products obtained are summarized in the table below.

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Table III

co · © Φ co

3ei- iprocken- weight Up
brought it
Bandage
middle tensile strenght at 200 ⁰ G at Tear length m at 200 ⁰ C m Elongation at break at 200 ^° C game extract
of
Bads Ender-
things-
nis g / m at 20 ^° C kg 20 ⁰ C 010 900 at 20 ^° C % g / m 9.4 kg '15.9 ·. 7th 570 4th 575 % 7.5 9 5 64.8 10.4 22.7 18.6 6th 185 5 0.00 6th 10.8 10 5 66.6 7.8 21.8 16.6 6th 515 5 725 5.8 10.6 11 5.5 66.5 2.9 20.6 ■ 11.1 5 805 5 975 5.7 6.2 12th 1.5 59.4 5.5 16.4 15.2 5 5 5 6th . · 15: ■ 1.5 59.4 17.2 4.5

cn co

Examples 14 to 16

The tests of some of Examples 4 to 8 are repeated, the fibers being carbon fibers with an average length of 6 mm and an average diameter of 9 microns is used.

The properties of the obtained nonwoven products
are given in Table IV below.

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• at Dry- weight Up
brought it at Table IV 15th at 200 ^° C Tear length at 200 ^° C Elongation at break at 200 ⁰ C t
> 8th game ejctract
of the bathroom Ender
things Bandage tensile strenght 85 at 20 ^° C at 20 ^° C nis middle 20 ⁰ C - .g / m ² 05 kg m 8th
I. g / m m % 8 * approx
ο kg ¹ co 17.7 ' 2.7 735 O, co 14- 5 73.4 10.3 1.85 1 135 585 0 ■ o, ro 15th 3.5 63.5 4, 900 0 -Jk
O 7th 2, 0.95 305 O, ro 16 62 335 0 1,

Examples 17-19

The procedure described in Examples 4 to 8 is followed and a pile made of glass fibers (average length: 3 mm, average diameter: 10 μ), bound with a polyvinyl alcohol, is produced. 25 % polyvinyl alcohol, based on the glass fibers, is used, ie 0.450 g polyvinyl alcohol for 1.800 g glass fibers.

The pile thus produced is impregnated 9 minutes after drying at 93 ⁰ C under partial vacuum (10 mm Hg) in a pickling bath, as used in Examples 4 to 8 polyamide-imide resin solution and then treated under the same conditions

Depending on the concentration of the impregnation bath made of heat-resistant Resin gives products whose properties are given in the table below.

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Table V

at Dry weight Up
brought it at tensile strenght 30th - 85 at 20O ⁰ C 40 at Tear length m at 20O ⁰ C m Fractional idea at % 200 ⁰ C game extract
of the bathroom Ender
things Bandage 20 ⁰ C 75 20 ⁰ C 470 660 ■ at 20 ^° C 1, OJ nis middle Ö g / m ² kg , 15 CO
CO S / m ² 7.8 kg 5. 05 3 610 1 525 % 1, 1 · * < 17th 3 65.2 11 950 375 0 1, ο, ¹ .5.5. 5. 2 1 2 ** ' 1Ö 3.5 67.9 1.8 8th, 4 ·, 1 1 0 2 19th 1.5 58.8 5, 0

Examples 20-23

As in Examples 4 to 8, nonwoven piles are made of aromatic polyamide fibers, somewhat bound with polyvinyl alcohol, using the previously described (Examples 4 to 8, paragraph a) specified amounts and works under the conditions described there.

This pile is then tied with the aid of a solution of a polytrimellitamide imide used in Examples 9 to 13, diluted with a mixture of N-methylpyrrolidone and xylene (80:20) in such a way that the dry product concentration is 10 % . This solution is applied to the pile by means of a spray gun fed with compressed air at 1 bar. The amount of binder applied is adjusted by varying the duration of the spraying.

The fleece obtained becomes that in Examples 4 to 8 (Paragraph c) is subjected to the heat treatment described.

The properties of the obtained nonwoven products are shown in the following table.

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Table VI

at Spray C. g / m ² tensile strenght at 200 ^° C at Tear length at 200 ^° C Elongation at break at 200 ⁰ C % game duration
(sec) } eweight at 20 ^° C kg 20 ⁰ C m at 20 ^° C Ender-
productive
nis bandage
middle 3 kg m ■ % ,8th · O
to g / m ² 4th 7.9 4th 2,660 4th , 6 co
NJ 2 ° 5 12th 13.15 10.8 5 410 3,585 4.9 5 , 5 O 21 5 59.7 11 17.05 15.2 7th 660 4 580 5.4 8th 22nd 15th 60.4 24.45 17.7 8th 380 5 240 6.9 - 23 15th 66.4 27.75 240 8.1 67.5

Example 24

The procedure is as in Examples 20 to 23, but using polytrimellitamide-imide fibers with a fiber average length of 6 mm and a titer of 2.2 dtöx, obtained by dry spinning a polymer with an inherent viscosity of 1.01 (solution with 5g / l in N-methylpyrrolidone) are preserved. This polymer is the reaction product of

100 moles of 4,4'-diisocyanatodiphenylmethane . 80 moles of trimellitic anhydride 20 moles of terephthalic acid.

The properties of the obtained nonwoven products are as follows, for a spray time of 5 seconds:

Weight: 62.2 g / m ²

Weight of applied binder: 4.6 g / m tensile strength at 2O ⁰ C (for a width of 5 cm): 7.25 kg tensile strength at 200 ° C (for a width of 5 cm): 4.85 kg tenacity at 20 ⁰ C: 2330 m
Tear length at 200 ^° C.: 1560 m
Elongation at break at 20 ^° C: 6.1%
Elongation at break at 200 ^° C.: 7 %.

Example 25

A non-woven product made from asbestos fibers without a binder (asbestos paper) is impregnated and sold under the Trade name QUINTERRA is available from Johns Manville, in the polyamide-imide resin solution used in Examples 4-8.

The properties of the paper used are:

Thickness: 220 μ; Weight: 200 g / m; the fibers have an average diameter of 10 μ and an average length between 10 and 100 μ; the tensile strength

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- 25 - 226Ί 619

This paper at 2O ⁰ C. 1.635 kg (for a width of 5 cm).

The properties of the products obtained are the following:

Dry extract of the impregnation solution: 5 % Weight of the binder applied: 7 g / m 2.

2 "

Tensile strength at 20 C: 6.70 kg (width 5 cm)

at 200 ^° C: 6.22 kg (width 5 cm) elongation at break at 20 ^° C: 1.2 % (width ^ 5 cm),

Tear length

at 200 ⁰ C: 2.2% (width -5 cm) at 20 ⁰ C: 680 m at 200 ⁰ C: 633 m.

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Claims (6)

Claims 1. Nonwoven product, consisting of a fleece of fibers bonded to one another by a synthetic polymer, characterized in that a) the material forming the fibers is infusible or has a melting point above 180 C , b) the binder is a polyamide-imide and c) the proportion by weight of the binder is 5 to 150 % of the weight of the dry fibers used . 2. Nonwoven product according to claim 1, characterized in that the fibers are inorganic and / or organic fibers. 3. Nonwoven product according to claim 1 or 2, characterized in that the binder is a polymer which has a number of groupings of the formula ■■■■ ··. / ^co \. -NH-Q-N R-CO- (I) in which the symbol Q means a divalent radical which contains at least one benzene ring, and the symbol E represents a trivalent aromatic radical. 4. Nonwoven product according to one of claims 1 to 3i, characterized in that the polyamide-imide has a reduced viscosity between 30 and 180 cnr / g (measured in 0.5% solution in N-methylpyrrolidone) . 5. Nonwoven product according to claim 3 »characterized in that that the polymer of the formula I is the reaction product of trimellitic anhydride with 4,4'-diisocyanatodiphenyl ether is. 309827/1024 6. Nonwoven product according to claim 5 * characterized in that that the polymer of formula I is the reaction product of trimellitic anhydride with 4,4- '-Mi socyanat odiphenylmethane is. 7 · Process for the production of products according to one of Claims Λ to 6, characterized in that a) a dry fiber fleece is formed, b) this fleece in contact with a solution of Polyaaiid-imid is brought and c) the product thus obtained is dried. 309827/1024