Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation specified as porous or permeable to...
Reexamination Certificate
1999-08-25
2001-10-09
Copenheaver, Blaine (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation specified as porous or permeable to...
C442S062000, C442S076000, C442S110000
Reexamination Certificate
active
06300257
ABSTRACT:
The invention relates to extrusion-coated nonwoven sheeting of polyethylene, polypropylene, polyethylene terephthalate or polyamide, which is coated on one side with polyolefins, has a textile character and is suitable for use in the hygiene area, in the medicine area, in the textile and clothing industry, in the automobile industry as well as in construction.
The manufacture of nonwoven sheeting in the form of plastic nonwovens by the staple fiber technology, by the spunbonded technology and by the melt-blow technology (Fourne, F., Chemiefasern/Textilindustrie 81 (1979),445-449; 95 (1993), 811-822; DE 195 21 466; DE 19 620 379), as well as by the afterstretching of plastic nonwoven (DE 195 01 123; DE 195 01 125) is known.
Laminating, thermal bonding, ultrasonic welding and extrusion coating are the usual methods for applying coatings on plastic nonwovens.
Known examples of plastic nonwovens, which were produced by laminating plastic film on plastic nonwovens, are polyethylene-coated polypropylene nonwovens (French patent 2,729,328), PVC-coated polyester nonwovens (U.S. Pat. No. 4,591,526) and polypropylene-coated nonwoven materials (U.S. Pat. No. 5,169,712).
Known examples of coated plastic nonwovens, which were produced by thermal bonding, are polyethylene-coated polypropylene nonwovens (German patent 3,515,580) and polypropylene-coated plastic nonwovens (WO 95/11803; German patent 19 534 704; German patent 19 534 702).
Known examples of coated plastic nonwovens, which were produced by ultrasonic welding of film to nonwoven material, are polyethylene-coated polyethylene nonwovens (European patent 0 325 543) and film-coatings of polypropylene and textile fabrics (European patent 0 505 027).
Known examples of extrusion-coated plastic nonwovens are acrylate-coated polyethylene terephthalate nonwovens (French patent 2,662,603), polyethylene-coated polypropylene nonwovens (SU 1,514,653; European patent 0 474 123) and EVA-coated to polyethylene nonwovens (European patent 0 291 598).
Known bonding agents for bonding agent intermediate layers to improve adhesion of the polyolefins coating on the textile fabrics are acid-grafted or acid anhydride-grafted polypropylenes, ethylene (meth)acrylate copolymers, EVA copolymers, polyisocyanates or polyurethanes (Japanese patents 52094383 and 60250938).
Finally, the manufacture of films with a high porosity, by stretching polyolefins films, which contain large proportions of fillers, is also known (European patents 0 352 802 and 0 779 325) is also known.
The disadvantage of the known solutions for nonwoven sheeting with porous polyolefin coating consists therein that nonwoven sheeting with thin polyolefin coatings, which meet the requirements of coating thickness, number of pores and pore size distribution, cannot be produced by known technologies.
It is an object of the present invention to develop nonwoven sheeting with a thin polyolefin coating, which has a large number of pores with a very small pore diameter and are suitable for use in the hygiene area, in the area of medicine, in the textile and clothing industry, in the automobile industry as well as in construction.
The inventive objective was accomplished by nonwoven sheeting with a textile character, extrusion coated on one side with polyolefins and having a tensile strength of 4 to 20 MPa in the longitudinal direction and 2 to 15 MPa in the transverse direction and a total weight per unit area of 10 to 100 g/m
2
,
the extrusion coatings of polyolefins having a weight per unit area of 5 to 70 g/m
2
and preferably of 6 to 40 g/m
2
, a white crackling cloudiness of 0.1 to 5 percent and preferably of 0.1 to 2 percent, a pore area distribution, for which at least 90 percent of all pores ranging in area from 0.03 to 0.20 &mgr;m
2
and the maximum pore area is less than 1 &mgr;m,
and the nonwoven sheeting consisting of polyethylene and/or polypropylene and/or polyethylene terephthalate and/or polyamide and having a weight per unit area of 5 to 100 g/m
2
and preferably of 10 to 40 g/m
2
,
the extrusion coatings, pursuant to the invention, consisting of polyolefins of
a) ethylene homopolymers or copolymers of 70 to 99 percent by weight of ethylene and 30 to 1 percent by weight of &agr;-olefins with 4 to 18 carbon atoms and/or vinyl acetate and/or aliphatic C
1
to C
4
alkyl (meth)acrylates with melt indexes of 0.1 to 100 g/10 minutes at 190° C./2.16 kg and/or
b) propylene homopolymers or copolymers of 70 to 99 percent by weight of propylene and 30 to 1 percent by weight of ethylene and/or &agr;-olefins with 4 to 18 carbon atoms,
c) optionally 1 to 50 percent by weight and preferably 5 to 30 percent by weight, based on the propylene polymers b), of modified propylene polymers with melt indexes of 0.1 to 50 g/10 minutes at 230° C./2.16 kg and preferably of 1 to 40 g/10 minutes at 230° C./2.16 kg and a ratio of the intrinsic viscosity of the modified polypropylene to the intrinsic viscosity of the unmodified polypropylene with largely the same weight average molecular weight of 0.20 to 0.95,
d) 10 to 60 percent by weight, based on the sum of the polyolefins, of organic and/or inorganic fillers with a particle diameter, measured over the longest extent of the particles, of 0.1 to 10 &mgr;m and preferably of 0.5 to 5 &mgr;m, and
e) 0.01 to 2.5 percent by weight of stabilizers, 0.01 to 1 percent by weight of processing aids, in each case based on the sum of the polyolefins, and optionally 0.1 to 1 percent by weight of antistats and/or 0.05 to 1 percent by weight of nucleating agents, in each case based on the sum of the polyolefins, as auxiliary materials,
and in which the nonwoven sheeting, extrusion-coated with polyolefins, is produced pursuant to the invention by a method, for which the nonwoven sheeting, with a weight per unit area of 10 to 70 g/m
2
and preferably of 20 to 40 g/m
2
, is extrusion coated with the aforementioned mixtures of polyolefins and 10 to 60 percent by weight, based on the sum of the polyolefins, of organic and/or inorganic fillers, the residual moisture content of the mixtures preferably being less than 600 ppm, from the melt at mass temperatures of 170° to 290° C. and at an equipment speed of 50 to 300 m/min and preferably of 150 to 250 m/min, and the coated nonwoven sheeting is subjected at temperatures of 60° to 0° C. below the crystallization temperature of the extrusion coatings of polyolefins to longitudinal stretching of 1:1.1 to 1:6 and preferably of 1:1.1 to 1:2 and subsequently, at temperatures of 80° to 1° C. and preferably of 60° to 2° C. below the melting temperature of the extrusion coatings of polyolefins, to a transverse stretching of 1:1.1 to 1:6 and preferably of 1:1.1 to 1:2, the white crackling cloudiness being achieved by the stretching, particularly by the longitudinal stretching.
The ethylene homopolymers or ethylene copolymers, optionally contained in the extrusion coatings of the inventive, extrusion-coated nonwoven sheeting, preferably are polyethylenes with densities ranging from 0.90 to 0.94 g/cc, which have been synthesized using highly active Ziegler-Natta catalysts or metallocene catalysts.
Copolymers of ethylene and vinyl acetate and/or aliphatic C
1
to C
4
alkyl (meth)acrylates are contained in the extrusion coatings of the inventive, extrusion-coated nonwoven sheeting preferably if the nonwoven sheeting contains polyamide and/or polyethylene terephthalate fibers and the extrusion coating is applied as a co-extrusion coating for improving the interlaminar bonding strength, the co-extrusion layer, facing the nonwoven sheeting, containing the ethylene copolymers.
The polypropylene homopolymers or polypropylene copolymers, optionally contained in the extrusion coatings of the inventive, extrusion-coated nonwoven sheeting, preferably are propylene homopolymers and/or copolymers, synthesized using Ziegler-Natta catalysts or metallocene catalysts from propylene, ethylene and/or &agr;-olefins with 4 to 18 carbon atoms with a propylene content of 75.0 to 99.9 percent by weight in the form of the random copolymers, block copolymers and/or
Kirchberger Manfred
Paulik Christian
Wolfsberger Anton
Borealis AG
Copenheaver Blaine
Jordan and Hamburg LLP
Pratt Christopher C.
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