HK1174369B

HK1174369B - Primary carpet backing

Info

Publication number: HK1174369B
Application number: HK13101291.9A
Authority: HK
Inventors: Edze Jan Visscher
Original assignee: Bonar B.V.
Priority date: 2009-12-09
Filing date: 2010-12-07
Publication date: 2017-04-28

Description

Primary backing for carpet

Technical Field

The present invention relates to primary carpet backings comprising at least two different fiber layers.

Background

Nonwoven primary carpet backings for tufted carpets have been known for many years. Nonwoven primary carpet backings used in carpet manufacture are nonwovens comprising a backbone of polyester fibers, such as PET, or nonwovens comprising a backbone of polypropylene fibers. The term "fiber" as used herein refers to both staple/staple and filament.

In general, polypropylene or polyester fibers are filaments in the range of 1 to 25dtex, preferably in the range of 2 to 20dtex, most preferably in the range of 5 to 15dtex, which provide the required processing stability. The unit dtex defines the fineness of the filaments as their grammage per 10000 meter.

The skeletal fibers can be entangled by mechanical needling and/or hydroentanglement using fine water jets, and optionally bonded using a chemical binder.

Alternatively, a lower melting polymer in the form of fibers, or added as a powder or granules, can be used, which achieves thermal bonding of the skeletal fibers, e.g., by calendering or by air bonding, etc. When the lower melting polymer is present in the form of a fiber, the polymer can be present as a separate monocomponent fiber, or the lower melting polymer can be present in the same fiber as the backbone polymer in a so-called bicomponent or multicomponent fiber. Bicomponent fibers are well known in the art, for example as side-by-side, core/sheath or orange-peel type fibers (segmented pie fibers). Alternatively, fibers composed of a single polymer but having different degrees of crystallinity along the length of the fiber can be used as bicomponent fibers because the different degrees of crystallinity result in fiber segments composed of polymers having different melting points along the length of the fiber. This effect can be obtained, for example, by drawing the fibres in a spin-draw process to different degrees to obtain different degrees of crystallinity and thus varying the melting point along the length of the fibres, as disclosed in WO 93/13254.

In the case where both the backbone polymer, such as polyester or polypropylene, and the lower melting polymer are present as separate monofilaments, a type of so-called twin-filament nonwoven is formed. Alternatively, the lower melting polymer can be present in the same filament as the backbone polymer, thereby forming a bicomponent filament nonwoven.

WO03/033801 discloses a multi-layer nonwoven carpet backing in which the composition varies/differs in different sections/zones within a single nonwoven layer, thereby affecting the mechanical properties of the sections within the single layer to facilitate optimum molding of tufted automotive carpets.

US6,808,786 discloses a two-part primary carpet backing for improved acoustic properties. The first layer is a woven or non-woven material. The second base fabric layer is formed of a microfilament spunlace material to obtain acoustical properties for sound absorption. The two layers are joined together in a separate production step by means of adhesive tape.

The process for manufacturing a tufted carpet comprises the steps of: a carpet backing material is provided to a tufting machine and tufted using a tufting yarn to obtain a carpet blank having a face exhibiting tufts and a back forming backstitches. The tufts are the visible portions of the tufted yarn on the front face of the greige or carpet. The backstitches are the visible portions of the tufted yarn on the back of the carpet blank.

Over the years, improvements in nonwoven primary carpet backings have continued to meet the ever-tightening demands of carpet manufacturers and consumers. New tufting techniques, such as high-low tufting techniques for producing carpets with high and low tufts in a single carpet, require a primary carpet backing with improved needle holding capability to hold the tufts in place during the tufting process. Of particular importance are improving the appearance of the shaped carpet, allowing effective repair of defects occurring during tufting, and (by providing lower tuft-needle penetration resistance and reducing needle bias during tufting) improving tuftability, avoiding back side looseness (backstag), improving needle retention and reducing noise during tufting.

The newly formed tufts in the carpet blank are held in place by the needle holding capability of the carpet backing material. Needle retention is the force required to remove the loop of the carpet blank from the back. Which determines how strongly the interaction between the primary carpet backing and the tufted yarns is. Needle retention determines the possibility of failure in subsequent processing steps after tufting until the application of a pre-coat to lock the tufts in place. These processing steps may include dyeing, precoating, tentering, steaming and/or shipping of the carpet web. Each of these processing steps is performed under harsh conditions related to temperature and/or applied tension, which places high demands on the carpet backing material. The tuft-bonding properties of the pre-coat layer primarily determine how well the tufts are held in place in the pre-coated carpet. After pre-coating, a thick layer may be applied to the back of the pre-coated carpet and/or a secondary carpet backing may be applied.

The primary carpet backing should exhibit good tuft retention properties. The primary carpet backing should have a high needle holding capacity to hold the tufts in place during the dynamic tufting process to obtain tufts of substantially the same height and thus a flat carpet surface in the carpet blank. The needle holding capacity of the primary carpet backing is the capacity to place the tufts in place during the tufting process to form the tufts and to hold the tufts in place after formation during the formation of the next tufts. Which determines the face and back side looseness of the carpet blank during the tufting process. Back side ravel is a loose or uneven/flat backstitch in the carpet blank, essentially the tufts that were previously on the front side of the carpet are now (partially) on the back side. During subsequent processing steps, such as dyeing and pre-coating, the needle retention of the primary carpet backing should be high enough to keep the carpet surface as it is during tufting.

To lock the tufts in place in the carpet blank, a pre-coat may be applied to the back of the carpet blank. Tuft bind is the force required to completely remove a tuft from the face of the (pre-coated or formed) carpet. Which determines how strong the bond between the pile fibers of the primary carpet backing and the adhesive coating is. The precoat is typically applied to the back of the carpet blank as a latex solution or latex foam, followed by drying of the latex to form a bond between the base of the tufts and the primary carpet backing.

If the precoat has too high an affinity for the carpet backing material, the precoat may become visible on the face of the carpet completely through the carpet backing. This is known as latex bleed, which is undesirable in certain carpet constructions.

If the adhesion of the pre-coat to the carpet backing material is too low, the pre-coat will not form a sufficiently strong bond between the base of the tufts and the carpet backing to hold the tufts in place during further processing. In addition, problems arise when the primary carpet backing is poorly bonded to the other components of the formed carpet structure when the selvedge is cut.

Typically, the tufts cover the entire surface of the carpet, but under certain conditions the primary carpet backing may become visible during use of the carpet, especially when the carpet is mounted on an uneven surface. One example of such a situation is the use of such nonwovens in automotive carpets. Depending on the geometry of the vehicle body floor, the carpet must be strongly bent, i.e. deformed, in different areas. Deformations in the region of the transmission channel are of course particularly pronounced. In this case, it is advantageous that the primary carpet backing has the same color as the tufted yarns. When using pre-dyed tufted yarns to produce a carpet, the primary carpet backing should have substantially the same color as the pre-dyed tufted yarns. However, it is not economical for the primary carpet manufacturer to produce a different nonwoven primary carpet backing for each available color of tufted yarn, and it is also not economical for the carpet manufacturer to stockpile a large inventory of primary carpet backings of different colors.

Alternatively, undyed, so-called primary white tufting yarns can be used to tuft the primary carpet backing. The carpet grey cloth may be dyed in a subsequent processing step. Preferably, the primary carpet backing has good dyeability to avoid a (too large) color mismatch between the dyed tufted yarns and the dyed primary carpet backing, which would allow the primary carpet backing to remain visible when bent. Furthermore, there are carpet constructions in which: wherein the primary carpet backing is visible even when the carpet is not flexed. In principle, only the top side of the primary carpet backing facing the carpet front side needs to be dyed.

It is an object of the present invention to improve upon the above-mentioned needs for nonwoven primary carpet backings.

Disclosure of Invention

The object of the invention is achieved by a primary carpet backing comprising at least a first and a second fiber layer, which primary carpet backing is characterized in that both the first and the second fiber layer have a uniform composition throughout the fiber layer, wherein the fibers have a linear density in the range of 1 to 25dtex, preferably 2 to 20dtex, more preferably 5 to 15dtex, wherein both the first and the second fiber layer comprise at least two different polymers and at least one polymer comprised in the first layer is different from the polymer comprised in the second layer.

A fibre layer as used herein must be understood to mean a layer of non-woven fibres laid randomly.

As used herein, consistent composition must be understood as: the fiber type and amount of fibers throughout the layer are constant within the tolerances of standard nonwoven production processes. The first and second fibrous layers each comprise at least two different polymers. Preferably, the different polymers in one fibrous layer have different melting points. When a fibrous layer is composed of two different polymers, one polymer will have a lower melting point than the other polymer.

In a preferred embodiment of the invention, the primary carpet backing is thermally bonded by means of a binder polymer derived from fibers. Since the melting temperature of the lower melting polymer in each fiber layer may be, and preferably is, different, the thermal bonding process should be performed at a temperature corresponding to the lower melting polymer with the highest melting point. For example, when the first layer comprises PET and PA6 polymers and the second layer comprises PET and PP polymers, the lower melting polymer is PA6 for the first fiber layer and PP for the second fiber layer. Since PA6 has a higher melting temperature than PP, the nonwoven should be thermally bonded at the melting temperature of PA6.

In a preferred embodiment of the present invention, different polymers are present in the individual fibers to form a primary carpet backing comprising a layer of a bi-filamentary nonwoven.

The primary carpet backing according to the present invention may comprise an additional layer of fibers consisting of only one polymer. For example, the primary carpet backing may be composed of a first fibrous layer of polyamide, e.g. PA6, a second fibrous layer composed of separate polyester and polyamide fibers (forming a two-filament non-woven layer), a third fibrous layer composed of separate polyester and polyolefin fibers (forming a second two-filament non-woven layer) and optionally a fourth layer of polyolefin, e.g. PP.

In another preferred embodiment of the present invention, different polymers are co-present in the bicomponent fibers to form a carpet backing comprising a layer of a bi-filamentary nonwoven. More preferably, different polymers are co-present in the core/sheath bicomponent fiber.

In a preferred embodiment of the invention, the different polymers in the first fibrous layer are present in separate fibers and the different polymers in the second fibrous layer are present in bicomponent fibers to form a combination of a biconstituent nonwoven layer and a bicomponent nonwoven layer.

In another preferred embodiment of the invention, the primary carpet backing consists of a first layer consisting of core/sheath filaments having a core of polyester, such as polyethylene terephthalate (PET), and a sheath of Polyamide (PA), such as PA6, and a second layer consisting of core/sheath filaments having a core of polyester, such as polyethylene terephthalate (PET), and a sheath of polyolefin, such as PP. The presence of polyamide in the front side of the primary carpet backing improves the dyeability of the primary carpet backing without having to dye all the fibres in the entire primary carpet backing, when the layer consisting of core/sheath filaments with a polyester core and a polyolefin sheath is located on the back side of the primary carpet backing and the layer consisting of core/sheath filaments with a polyester core and a polyamide sheath is located on the front side of the primary carpet backing.

When the layer consisting of core/sheath filaments with a polyester core and a polyamide sheath is located on the back side of the primary carpet backing and the layer consisting of core/sheath filaments with a polyester core and a polyolefin sheath is located on the front side of the primary carpet backing, the adhesion of the latex on the back side is improved to lock the tufts in place, while the polyolefin present in the front side of the primary carpet backing prevents the latex from penetrating the primary carpet backing due to the low affinity of the latex for the polyolefin sheath material.

In another preferred embodiment of the invention, the primary carpet backing consists of three fibrous layers, both the first and third layers consisting of core/sheath filaments having a polyester core, such as a polyethylene terephthalate (PET) core, and a Polyamide (PA) sheath, such as a PA6 sheath; the second fibrous layer, which is located between the first and third layers, is comprised of core/sheath filaments having a polyester core, such as a polyethylene terephthalate (PET) core, and a polyolefin sheath, such as a PP sheath. The presence of the polyamide in one layer on the back side of the primary carpet backing improves the adhesion of the latex to the primary carpet backing and thus improves tuft bonding in the carpet, while the presence of the polyolefin in the second (intermediate) layer prevents penetration of the latex through the primary carpet backing to the front side of the carpet blank. The presence of polyamide in a layer on the face side of the primary carpet backing improves the dyeability of the primary carpet backing, thereby reducing the visibility of the primary carpet backing in the formed carpet.

The primary carpet backing according to the present invention also improves needle retention because the lower melting polymer in each layer can be adjusted to maximize the friction of the primary carpet backing with the tufted yarn polymer.

In another preferred embodiment, the primary carpet backing according to the invention may comprise one or more additional layers, each additional layer being selected from the group formed by a woven layer, a nonwoven layer, a scrim layer (scrimlayer), a unidirectional filament or yarn layer, and a film layer. Preferably, the primary carpet backing comprises an additional layer located between the first and second fibrous layers.

Additional layers may be used, for example, to provide additional reinforcement to the primary carpet backing to further improve needle retention and/or to further improve the barrier against latex penetration.

Detailed Description

Example 1

All samples were spun bonded using known techniques to deposit three layers of filaments on top of each other on the collector surface. In each sample, the basis weight of the base fabric was up to 126g/m². All filaments are of the core/sheath type. After deposition, the samples were thermally bonded at 230 ℃.

The comparative example consisted of three identical fibrous layers, each having 42g/m²And consists of bicomponent filaments having a core/sheath volume ratio of 74/26, a core of PET and a sheath of PA6, and a linear density of 15 dtex.

Sample 1 according to the invention consisted of two identical outer filament layers with a core/sheath volume ratio of 74/26, a core of PET and a sheath of PA6, and a linear density of 15dtex, and one inner layer with a core/sheath volume ratio of 74/26, a core of PET and a sheath of PP, and a linear density of 15 dtex. All three layers had 42g/m²Basis weight of (c).

The relevant properties of the sample are determined. The breaking strength and elongation at break before and after tufting were measured at a speed of 200mm/min according to EN29073-3 at 8 months 1992.

Needle penetration resistance has been determined by measuring the force required for a single needle (Groz-Beckert needle, model number HK 01R-W-P-B) to penetrate the primary carpet backing. The average, minimum and maximum penetration force of 3750 individual needle penetrations has been determined to obtain relevant parameters expressing penetration force, since the properties of the primary carpet backing will always be related to the tuft needle size (only a few mm)²) Quite considerably exhibiting significant variation.

The needle holding capacity of the primary carpet backings has been determined by means of tufting the primary carpet backings under conditions which are detrimental to the formation of backings and counting the total backings formed during tufting, i.e. the tufts completely removed from the grey carpet blank, within an area of 1m x 12.2cm containing 9600 tufts. Tufting was performed through a Groz-Beckert0660 needle under the following conditions: the gauge was 1/5 "(5.08 mm), the texturetex pa6.6 tufted yarn model 3252O2 x 1350dtex, the machine speed was 600rpm, the speed difference between the supply speed of the primary carpet fabric and the output speed of the carpet blank was 4.4%, the gauge was 40 needles per 10cm, and the yarn feed corresponded to a pile length of 11.8 mm. The pile length has been determined by pulling 100 tufts from a carpet blank and measuring the total length of tufted yarn removed. The pile length can be calculated by dividing the total length of the tufted yarns by the number of tufts removed.

TABLE 1

Characteristics before tufting
				Sample 1	Comparative example
Mass [ g/m ]²]	125	125
			MD Strength [ N/5cm]	196	485
CMD Strength [ N/5cm]	221	433
			MD elongation [% ]]	16	32
CMD elongation [% ]]	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 2

Characteristics after tufting
				Sample 1	Comparative example
Mass [ g/m ]²]	982	980
			MD Strength [ N/5cm]	418	438
CMD Strength [ N/5cm]	373	296
			MD elongation [% ]]	42	36
CMD elongation [% ]]	48	41
			Needle holding Capacity [ number of Loose Back)]	8	29

This example clearly shows that although the strength and elongation of the fabric according to the invention is reduced before tufting (table 1; about 50% to 60% lower than the comparative fabric), the fabric of the invention has an increased strength and elongation after tufting (table 2; about 25% higher than the comparative fabric). The primary carpet backing of the present invention has a lower needle penetration force which reduces the likelihood of needle deflection during tufting. Moreover, the amount of back side bulk in carpet blanks produced using backings according to the invention has been significantly reduced, i.e. from 29 back side bulks to 8 back side bulks.

Claims

1. A primary carpet backing comprising at least a first and a second fibre layer, wherein both the first and the second fibre layer are non-woven, randomly laid fibre layers, wherein the linear density of the fibres is in the range of 1 to 25dtex,

both the first fiber layer and the second fiber layer have a uniform composition throughout the fiber layers, and wherein both the first fiber layer and the second fiber layer comprise at least two different polymers, and at least one polymer comprised in the first fiber layer is different from a polymer comprised in the second fiber layer,

wherein the first fiber layer is a core/sheath filament composed of a polyester core and a polyamide sheath, and the second fiber layer is a core/sheath filament composed of a polyester core and a polyolefin sheath, or

The first fibre layer consisting of separate polyester fibres and polyamide fibres and the second fibre layer consisting of separate polyester fibres and polyolefin fibres, or

The first fiber layer is composed of separate polyester and polyamide fibers and the second fiber layer is a core/sheath filament composed of a polyester core and a polyolefin sheath.

2. The primary carpet backing according to claim 1 wherein the primary carpet backing is thermally bonded by means of a binder polymer derived from fibers.

3. The primary carpet backing according to claim 1 or 2 wherein the different polymers in the first fibrous layer are present in separate fibers and the different polymers in the second fibrous layer are present in bicomponent fibers.

4. The primary carpet backing according to claim 1 or 2 wherein the different polymers in both the first and second fibrous layers are present in separate fibers.

5. The primary carpet backing according to claim 1 or 2 wherein the different polymers in both the first and second fibrous layers are present in bicomponent fibers.

6. The primary carpet backing according to claim 3 wherein the bicomponent fibers are core/sheath bicomponent fibers.

7. The primary carpet backing according to claim 5 wherein the bicomponent fibers are core/sheath bicomponent fibers.

8. The primary carpet backing according to claim 5 wherein the bicomponent fibers in the first fiber layer consist of a polyester core and a polyamide sheath and the bicomponent fibers in the second fiber layer consist of a polyester core and a polyolefin sheath.

9. Primary carpet backing according to claim 1 or 2, wherein the primary carpet backing comprises an additional layer of fibres consisting of a polymer.

10. Primary carpet backing according to claim 1 or 2, wherein the primary carpet backing comprises an additional layer of fibers consisting of at least two different polymers.

11. The primary carpet backing according to claim 10 wherein the primary carpet backing consists of a first fiber layer, a second fiber layer and a third fiber layer, wherein the different polymers in each fiber layer are present in bicomponent fibers, and wherein the bicomponent fibers in the first fiber layer and the third fiber layer consist of a polyester core and a polyamide sheath and the bicomponent fibers in the second fiber layer consist of a polyester core and a polyolefin sheath.

12. The primary carpet backing according to claim 1 or 2, wherein the primary carpet backing comprises one or more additional layers, each of the additional layers being selected from the group consisting of a woven layer, a nonwoven layer, a scrim layer, a unidirectional filament or yarn layer, and a film layer.

13. A tufted carpet comprising the primary carpet backing according to any one of claims 1 to 12.