Fusible chlorine-free vinyl acetate copolymer fibres

Details Fusible chlorine-free vinyl acetate copolymer fibres Fusible chlorine-free vinyl acetate copolymer fibres

1997-09-05

1999-03-09

Lipman, Bernard

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

5263231, 5263232, C08F 2226

Patent

active

058802398

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to fusible chlorine-free vinyl acetate copolymer fibres, to processes for their production and to their use as fibrous binders.
2. Background Art
To increase the resistance to mechanical load, fibrous structures, for example nonwoven fabrics, are bonded with binders. These binders can be employed in the form of solids, such as powders or fibres, or as liquids, in the form of solutions or dispersions. Fibrous binders have a number of advantages over aqueous binder dispersions. Bonding nonwovens by means of aqueous dispersions requires a special application machine and a drying unit for removing the aqueous phase from the dispersion. In addition to the expenditure on apparatus, the removal of water is also very expensive in terms of energy. In contrast, fibrous binders can be processed on the customary devices for production of textile sheet-like structures together with the fibres to be bonded. For example, the binder fibres can be laid out together with the fibres to be bonded, and the fibre material can be bonded with a far lower energy consumption by heating to the melting point of the binder fibres.
Conventional melt-fusible fibres which are employed for bonding textile sheet-like structures are, for example, polyolefins, such as polyethylene or polypropylene fibres, or polyesters, such as polyethylene terephthalate fibres. Nevertheless, these fibres have the disadvantage that their melt viscosity changes dramatically within a narrow temperature range. During processing of these fibres, the temperature and residence time during thermal bonding must be adhered to very precisely, since even small variations in temperature can cause the molten fibrous binder to run-off.
A wider temperature range for processing is available with copolymer fibres (CP fibres) based on vinyl acetate/vinyl chloride copolymer fibres. A disadvantage of these fibres is the high chlorine content, which leads to problems during disposal and re-use of textiles bonded therewith.
The object was therefore to provide a fusible thermoplastic fibre which has the same melting characteristics as the CP fibres but does not contain any chlorine. In addition, it should be possible to melt-spin the polymer, in order to bypass the disposal problems of polymers which can be spun only in solution.


SUMMARY OF THE INVENTION

The invention relates to fusible vinyl acetate copolymer fibres based on vinyl acetate copolymers comprising ethylenically unsaturated monomers whose homopolymers have a glass transition temperature Tg of 40.degree. to 120.degree. C., and unsaturated monomers whose homopolymers have a glass transition temperature Tg of -100.degree. to 0.degree. C.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferably, the vinyl acetate copolymers comprise 60 to 70% by weight of vinyl acetate, 15 to 25% by weight of one or more monomers b) and 3 to 10% by weight of one or more monomers c). To obtain an optimum melt viscosity, vinyl acetate copolymers of which the molecular weight corresponds to a Fikentscher K value (1% strength solution in tetrahydrofuran/water 93:7 (V/V) determined in accordance with DIN 53726) of 30 to 80 are preferred.
Preferred comonomers b) are vinyl esters of saturated aliphatic monocarboxylic acids having 5 to 9 C atoms which contain a quaternary C atom in the .alpha.-position relative to the carboxyl group, for example VeoVa5.sup.R or VeoVa9.sup.R or dimethyl fumarate, di-isopropyl fumarate, di-t-butyl fumarate, methyl t-butyl fumarate, dimethyl maleate, di-isopropyl maleate, di-t-butyl maleate, methyl t-butyl maleate, 4-t-butyl-cyclohexyl acrylate, t-butyl acrylate, methyl methacrylate or N-vinylpyrrolidone. Diisopropyl fumarate is particularly preferred as co-monomer b).
Preferred comonomers c) are vinyl laurate, dibutyl maleate, di-2-ethylhexyl maleate, dibutyl fumarate, di-2-ethylhexyl fumarate, ethylene and vinyl esters of saturated aliphatic monocarboxylic acids having 10 C atoms which contain a quaternary C atom in the .alpha.-position

REFERENCES:
patent: 621389 (1949-08-01), Dickey
patent: 2354744 (1944-08-01), Dreyfus
patent: 3714096 (1973-01-01), Biale
patent: 4826938 (1989-05-01), Mudge
patent: 4829139 (1989-05-01), Mudge
patent: 5276084 (1994-01-01), Cheng et al.
patent: 5525656 (1996-06-01), Heiling et al.
Hawley's Condensed Chemical Dictionary, Sax et al Feb. 91 p. 371.

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