Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Staple length fiber
Patent
1995-05-12
1996-10-01
Edwards, Newton
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Staple length fiber
428373, 525428, D02G 300
Patent
active
055609902
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a blend of melamine resin fibers and aramid fibers.
Fibers comprising melamine-formaldehyde condensation products are known, for example from DE-B-2 364 091. They are nonflammable, flame resistant and heat resistant. Owing to these properties, they are used for manufacturing fire resistant textiles. However, there are applications for which the fibers are not sufficiently strong or abrasion resistant.
Fibers comprising polycondensation products of isophthalic or terephthalic acid and phenylenediamine have likewise been known for a long time. They too have a favorable behavior in a fire environment. However, on processing into yarn by the worker-and-stripper carding process the low processing speed of the aramid staple fibers is disadvantageous.
SUMMARY OF THE INVENTION
It is an object of the present invention to improve the properties of melamine resin fibers on the one hand and the properties of aramid fibers on the other.
We have found that this object is achieved by blends of the two fibers.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to DE-B-2 364 091, the melamine resin solution used for spinning the melamine resin fibers may have added to it solutions of other fiber-forming polymers, including solutions of polyamides in organic solvents. Preference is given to adding to the melamine resin solution aqueous solutions of polyvinyl alcohol as a way of improving the mechanical properties of the fibers produced by the spinning process. This reference thus involves spinning mixtures or solutions of different polymers to produce blended, multicomponent fibers, whereas the present invention involves blending different ready-produced fibers to thereby produce fiber blends.
A. Melamine resin fibers are notable for their high temperature resistance and nonflammability. Their preparation and properties are known, for example from DE-A-2 364 091. They are preferably produced from highly concentrated solutions of melamine-formaldehyde precondensation products, after addition of an acidic curing agent, by rotospinning, drawing out, extrusion or fibrillation. The fibers obtained are generally predried with or without stretching, and the melamine resin is usually cured at from 120.degree. to 250.degree. C. The fibers are usually from 5 to 25 .mu.m in thickness and from 2 to 2000 mm in length. Particularly thermally stable fibers are obtained when up to 30 mol %, in particular from 2 to 20 mol %, of the melamine in the melamine resin is replaced by a hydroxyalkylmelamine, as described in EP-A-221 330 or EP-A-523 485. Such fibers have a sustained use temperature of up to 200.degree. C., preferably up to 220.degree. C. In addition, minor amounts of melamine can be replaced by substituted melamines, urea or phenol. Particular preference is given to condensation products obtainable by condensation of a mixture containing as essential components ##STR1## where X, X' and X" are each selected from the group consisting of --NH.sub.2, --NHR and --NRR', and X, X' and X" are not all --NH.sub.2, and R and R' are each selected from the group consisting of hydroxy-C.sub.2 -C.sub.10 -alkyl, hydroxy-C.sub.2 -C.sub.4 -alkyl-(oxa-C.sub.2 -C.sub.4 -alkyl).sub.n, where n is from 1 to 5, and amino-C.sub.2 -C.sub.12 -alkyl, or mixtures of melamines I, and unsubstituted or substituted by radicals selected from the group consisting of C.sub.1 -C.sub.9 -alkyl and hydroxyl, C.sub.1 -C.sub.4 -alkanes substituted by two or three phenol groups, di (hydroxyphenyl) sulfones, or mixtures of these phenols, to formaldehyde within the range from 1:1.15 to 1:4.5.
B. Aramid fibers are notable for their favorable behavior in a fire environment. They are preferably produced by spinning solutions of polycondensation products of isophthalic or terephthalic acid with para- or meta-phenylenediamine in solvents, for example a mixture of N-vinylpyrrolidone and hexamethylphosphoramide. The resulting continuous fibers are then cut into staple fibers, whose thickness
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patent: 5322915 (1994-06-01), Weiser et al.
Berbner Heinz
Burlone Dominick A.
Herbst Gernot
Ilg Otto
Ott Karl
BASF - Aktiengesellschaft
Edwards Newton
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