NONWOVEN FABRIC

Abstract

The present invention relates to a nonwoven fabric comprising continuous spunbonded bicomponent fibers which consist of: 0 to 95% by weight of an aromatic polyester (A) in a core; to 50% by weight of a polyester blend (B) containing a) 65 to 95% of an aromatic polyester (BA) and b) 5 to 35% by weight of an aliphatic-aromatic polyester (BB) with a glass temperature below 0° C. in a sheath surrounding the core; and 0 to 5% by weight of at least one additive (C); wherein the % by weight are based in each case on the total weight of the components (A) and (B) and optionally (C); and wherein the aromatic polyesters (A) and (BA) are selected from the group consisting of poly(ethylene terephthalate) and poly(butylene terephthalate).

Claims

1.-5. (canceled)

6. A nonwoven fabric comprising continuous spunbonded bicomponent fibers which consist of: 50 to 95% by weight of an aromatic polyester (A) in a core; 5 to 50% by weight of a polyester blend (B) containing: a) 65 to 95% of an aromatic polyester (BA) and b) 5 to 35% by weight of an aliphatic-aromatic polyester (BB) with a glass temperature below 0° C. in a sheath surrounding the core; and 0 to 5% by weight of at least one additive (C); wherein the % by weight are based in each case on the total weight of the components (A) and (B) and optionally (C); and wherein the polyesters (A) and (BA) are selected from the group consisting of poly(ethylene terephthalate) and poly(butylene terephthalate).

7. A nonwoven fabric according to claim 6, wherein the polyesters (A) and (BA) are both poly(ethylene terephthalate).

8. A nonwoven fabric according to claim 6, wherein the aliphatic-aromatic polyester (BB) comprises: BB-a) 30 to 70 mol %, based on components BB-a bis BB-b, of a C.sub.4-C.sub.18-dicarboxylic acid; BB-b) 30 to 70 mol %, based on components BB-a bis BB-b, of terephthalic acid; BB-c) 98 to 100 mol %, based on components BB-a bis BB-b, of 1,3- propane diol or 1,4-butane diol; BB-d) 0 to 1,5% by weight, based on components BB-a bis BB-c, of branching agent or chain extender.

9. A nonwoven fabric according to claim 6, wherein the fabric weight is in the range of 25 gsm to 400 gsm.

10. A nonwoven fabric according to claim 9, wherein the fabric weight is in the range of 50 gsm to 200 gsm.

Description

EXAMPLES

[0091] Measurement of Physical Properties

[0092] Directly after the nonwoven was produced samples were cut for mechanical testing and weight determination. The strips for the tensile and elongation at break had a 5 cm width.

[0093] Mechanical testing for tensile strength and elongation at break: Strips of the nonwoven in the machine direction (MD) and in the direction were cut and cross-machine direction measured (ISO 9073-3).

[0094] Determining weight of nonwoven: The mass of the nonwoven is determined as gram per square meter (ISO 9073-1).

[0095] Starting Materials:

[0096] Aromatic polyester (components A and BA):

[0097] PET type 5520 from Invista with an intrinsic viscosity (IV) of 0.66 was used. The PET was dried at 160° C. to a moisture content of less than 50 ppm.

[0098] Aliphatic-aromatic polyester (component BB):

[0099] Polyester BB consisting of the monomers 1,4-butanediol (50 mol %), adipic acid (25 mol %) and terephthalic acid (25 mol %) was used. The polyester BB was dried at 70° C. overnight before use to a moisture content below 100ppm. The melt volume rate (MVR) of the used polyester was measured at 190° C., 2.16 kg. The MVR (190° C., 2.16 kg) for polyester BB was 3,4 ml/10 min.

TABLE-US-00001 TABLE 1 Experiment number: ST1 CE1 CE2 CE3 1 2 ST2 3 ST3 4 Core: PET wt % 100 96 93 90 100 100 100 100 100 100 Core: Polyester BB wt % — 4.0 7.0 10.0 — — — — — — Sheath: PET wt % 100.0 96.0 93.0 90.0 80 70 100.0 95.0 100.0 80 Sheath: Polyester BB wt % — 4.0 7.0 10.0 20.0 30.0 — 5 — 20.0 Spinneret number 1 1 1 1 1 1 2 2 1 1 Throughput per hole (g/min .Math. hole) 1.1 1.1 1.1 1.1 1.1 1.1 1.69 1.69 1.1 1.1 Line speed (m/min) 48.0 50.0 50.0 52.0 52.0 52.0 106 106 95.0 104.0 Throughput ratio core:sheath 65:35 65:35 65:35 65:35 65:35 65:35 65:35 65:35 65:35 65:35 Melt temperature die core (° C.) 297 291 291 288 288 289 286 286 297 288 Melt temperature die sheath (° C.) 299 291 290 279 287 283 287 287 299 285 Heat roll #1: Oil temperature (° C.) 255 245 245 245 245 240 255 250 255 245 Heat roll #2: Oil temperature (° C.) 253 243 243 243 243 238 253 248 253 243 Tensile strength MD (N) 311.1 235.9 230.2 245.9 451.2 402.9 107.4 119.7 174.0 223.2 Tensile strength CD (N) 90.8 63.9 64.1 78.0 222.1 238.2 57.0 65.1 55.4 97.4 Elongation MD (%) 33.3 28.7 32.3 37.7 72.2 67.3 27.6 38.3 34.6 23.6 Elongation CD (%) 33.6 35.2 39.8 48.3 71.6 62.0 38.2 45.1 40.8 58.6 Fabric weight (g/m.sup.2) 109.4 106.3 100.9 101.7 103.2 104.3 51.3 49.8 56.9 56.3 Improvement to comparison ST1 ST1 ST1 ST1 ST1 ST2 ST3 sample Improvement tensile MD (%) −24% −26% −21%  45%  30% 11%  28% Improvement tensile CD (%) −30% −29% −14% 145% 162% 14%  76% Improvement elongation MD (%) −14%  −3%  13% 117% 102% 39% −32% Improvement elongation CD (%)  5%  18%  44% 113%  85% 18%  44%

[0100] Preparation of spunbonded bicomponent fiber and nonwoven fabric formed therefrom:

[0101] The materials were dosed to twin-screw extruders. Both the sheath and the core composition are parallel prepared in separate twin-screw extruders. The dried polyesters were added through separate feeders based on the determined weight percentages. Melt pumps ensured a constant pressure of the polymer melt to the spin pack. In the spin pack the separate melt flows are combined and oriented into a sheath-core die design. The spinnerets used had 4982 holes/m (Spinneret 1) or 3200 holes/m (Spinneret 2). The amount of material for the sheath and the core were kept constant. The core had 65% by weight of the fiber and the sheath was 35% by weight of the fiber. Standard samples (ST1, ST2, ST3) did not contain any polyester BB. Comparative example samples (CE1, CE2, CE3) did contain polyester BB in equal amounts in the sheath and core. For experiment numbers 1,2,3 and 4 the amount of polyester BB selectively added to the sheath. The total throughput of materials was kept constant in the range of 325-329 kg/h. per meter of spinneret. The die temperature was kept at 290° C., but the melt temperatures were also lower, especially for the blends with the higher mixing ratios. The fiber was quenched by air in two stages Q1: 50° C. with a throughput of 3.8-5.4 m.sup.3/kg of fiber, throughput: and Q2: 25° C. with a throughput of 22-23 m.sup.3/kg of fiber.

[0102] The spun fiber was collected on belt with air suction. The speed of the belt was altered to change the weight of the collected nonwoven. The collected nonwovens were subsequently thermo bonded by calendering between two rolls heated by oil. The heat bonded nonwovens were collected on spools (Table 1).