PRIMARY CARPET BACKING

Abstract

A primary carpet backing comprising at least a first and a second layer of fibers, characterised in that both the first and the second layer of fibers is a nonwoven layer of randomly laid fibers, that both the first layer of fibers and the second layer of fibers has a uniform composition throughout the layer, wherein the linear density of the fibers is in the range of 1 to 25 dtex, wherein both the first layer of fibers and second layer comprises at least two different polymers and wherein at least one polymer comprised in the first layer is different from the polymers comprised in the second layer.

Claims

1. A primary carpet backing comprising at least a first layer of fibers, a second layer of fibers, and a third layer of fibers wherein: the first layer of fibers, the second layer of fibers, and the third layer of fibers are a nonwoven layer of randomly laid fibers, a linear density of the fibers is in a range of 1 to 25 dtex, the first layer of fibers, the second layer of fibers, and the third layer of fibers have uniform composition throughout each layer of fibers, the first layer of fibers, the second layer of fibers, and the third layer of fibers consist of two different polymers, the first layer of fibers, the second layer of fibers, and the third layer of fibers comprise polyester as a backbone polymer, at least one of the polymers in the first layer of fibers is different from one of the polymers in the second layer of fibers, the different polymers in each layer of fibers exist in bicomponent fibers, the bicomponent fibers in the first and third layer of fibers comprise a polyester core and a polyamide sheath, and the bicomponent fibers in the second layer of fibers comprise a polyester core and a polyolefin sheath.

2. The primary carpet backing according to claim 1, wherein the primary carpet backing is thermally bonded with a binder polymer originating from the fibers.

3. The primary carpet backing according to claim 1, wherein the primary carpet backing comprises one or more additional layers, each of the additional layers being selected from the group consisting of woven layers, nonwoven layers, scrim layers, layers of unidirectional filaments or yarns, and film layers.

4. A tufted carpet comprising the primary carpet backing according to claim 1.

5. The primary carpet hacking according to claim 1, wherein the different polymers in the first layer of fibers or the second layer of fibers have different melting points.

Description

Example 1

[0033] All samples were spunbonded using commonly known technology for depositing three layers of filaments on top of each other on a collector surface. In each sample, the basic weight of the backings amounted to 126 g/m.sup.2. The filaments were all of the core/sheath type. After deposition the samples were thermally bonded at 230 C.

[0034] The reference consisted of three identical layers of fibers, each having a basic weight of 42 g/m.sup.2 and consisting of bicomponent filaments having a 74/26 core/sheath volume ratio, a core of PET and a sheath of PA6, and a linear density of 15 dtex,

[0035] Sample 1 in accordance with the invention, consisted of two identical outer layers of filaments having a 74126 core/sheath volume ratio, a core of PET and a sheath of PA6, and a linear density of 15 dtex and an inner layer of 74/26 core/sheath volume ratio, a core of PET and a sheath of PP and a linear density of 15 dtex. All three layers had a basic weight of 42 g/m.sup.2.

[0036] The relevant properties of the samples were determined. Breaking strength and elongation at break before and after tufting measured in accordance with EN 29073-3 dated 08-1992 at a speed of 200 mm/min.

[0037] The needle penetration resistance has been determined by measuring the force required for a single needle, Groz-Beckert needle type HK01 R-W-P-B, to penetrate the primary carpet backing. The average, minimum and maximum penetration force of 3750 individual needle penetrations have been determined to obtain relevant parameters describing penetration force as a primary carpet backing will always show significant variation in properties on the level comparable to the dimensions of a tuft needle, being only a few mm.sup.2.

[0038] The stitch holding capacity of a primary carpet backing has been determined by means of tufting a primary carpet backing under conditions which are critical for backtag formation and counting the number of full backtags formed during tufting, i.e. counting the number of tufts which are removed completely from the greige carpet, in an area of 1 m by 12.2 cm containing 9600 tufts. Tufting took place with Groz-Beckert 0660 needles at a gauge of (5.08 mm), Texture Tex PA6.6 tufting yarns type 3252 O 21350 dtex, a machine speed of 600 rpm, a speed difference between the supply speed of the primary carpet backing and the output speed of the greige carpet of 4.4%, a stitch rate of 40 stitches per 10 cm and a yarn feed corresponding to a pile length of 11.8 mm. The pile length has been determined by pulling out 100 tufts from the greige carpet and measuring the total length of the removed tufting yarn. The pile length can be calculated dividing the total length of tufting yarn by the number of removed tufts.

TABLE-US-00001 TABLE 1 Properties before tufting Sample 1 Reference Mass [g/m.sup.2] 125 125 Strength in MD [N/5 cm] 196 485 Strength in CMD [N/5 cm] 221 433 Elongation in MD [%] 16 32 Elongation in CMD [%] 19 34 Average needle penetration resistance [N] 9.28 14.23 Minimum needle penetration resistance [N] 2.85 6.19 Maximum needle penetration resistance [N] 18.24 24.75

TABLE-US-00002 TABLE 2 Properties after tufting Sample 1 Reference Mass [g/m.sup.2] 982 980 Strength in MD [N/5 cm] 418 438 Strength in CMD [N/5 cm] 373 296 Elongation in MD [%] 42 36 Elongation in CMD [%] 48 41 Stitch holding capacity [Number of backtags] 8 29

[0039] The example clearly shows that, although the backing in accordance with the invention has reduced strength and elongation before tufting (Table 1; about 50 to 60% lower when compared to the reference backing), the inventive backing exhibits improved strength and elongation after tufting (Table 2; up to approximately 25% higher when compared to the reference backing). The needle penetration force of the inventive primary carpet backing is lower which reduces the chance of needle deflection during tufting. Also, the number of backtags in the greige carpet produced with the backing according to the invention has been reduced considerably, i.e. from 29 to 8 backtags.