ES2343687T3 - NON-WOVEN COMPOSITE MATERIAL CONTAINING CONTINUOUS FILAMENTS AND SHORT FIBERS. - Google Patents

Abstract

The present invention relates to a nonwoven material consisting of a mixture containing continuous filaments and short fibres, the continuous filaments being substantially mechanically bonded to each other due to entangling of fibres and filaments. According to the invention the continuous filaments in the material have a projected coverage of at least 1.1 and not more than 1.7. The invention also relates to a method of manufacturing such a nonwoven material.

Description

Nonwoven composite material containing continuous filaments and short fibers.

Technical field

The present invention relates to a material nonwoven compound according to the preamble of claim  1 and a method for manufacturing a nonwoven material in accordance with the preamble of claim 8.

Background of the invention

For cleaning applications a non-material fabric must be strong, absorbent, abrasion resistant and have reduced fraying, that is, during normal use the Fibers should not detach from the material.

One way to make nonwoven materials is use hydroentangling or spinning to mix and bond constituents  in the material. Hydroentangling is described, for example, in the CA Patent No. 841 938. It is known how to produce composite materials nonwovens comprising continuous filaments and short fibers by hydroentangled, see for example documents EP-E31-0333228, EP-B1-0 938 601 and WO 99/20821.

A problem found in the manufacture of such composite materials is that it is difficult to obtain a good integration of continuous filaments and short fibers only by hydroentangled resulting in composite materials produced often have two more or less pronounced faces, it is that is, one face contains predominantly short fibers and the other It contains predominantly continuous filaments. These two faces They have various drawbacks. First, the union of filaments and short fibers will be weaker than in a material compound in which short fibers and continuous filaments are well integrated, that is, homogeneously mixed, the resistance in the thickness direction will be low and there is a risk that the compound deslamine if both sides are pronounced. In addition, the "short fiber face" of said material will be frayed sensitive, i.e. loss of fibers from the surface, and the "filament face", will be sensitive to "the ball formation "when it wears out, that is, what parts of the filaments will protrude from the surface of this face.

In WO 99/20821 the associated problem with the bad mixture of the materials it is solved by applying a bonding material on at least one side of a cloth hydraulically matted comprising a fibrous component and a non-woven layer of substantially continuous filaments. Also in the document US-A-5,389,202 a cloth is used united of continuous filaments. In the document EP-B1-0 333 228 this problem is resolves by co-deposition of a mixture of non-elastic meltblown filaments and material fiber on a conveyor surface. The fibrous material is intermingling with the blown fibers in molten state just after to extrude the material of molten blown fibers to through the molten blow molding matrix so that the Materials are thoroughly mixed before matting.

Of the document EP-B1-0 938 601 is known how manufacture a nonwoven material by foaming forming a cloth fibrous of natural and / or synthetic short fibers directly on a layer of unbound continuous filaments and hydroentangling between yes the dispersion of the foamed fiber with the continuous filaments to form a composite material. By foaming an improved blend of synthetic fibers and / or natural with synthetic filaments before matting. A disadvantage of this method is the need for equipment for foaming and to care for the surfactants used for foaming, circulating in the water circuit.

Using a layer of continuous filaments no together it is easier to obtain a well integrated material than with a layer of continuous filaments attached, so the consumption of energy in the entangled stage will be less than what is needed to integrate fibers with a layer of continuous filaments attached. However, it has been shown that the properties of the material obtained by means of said manufacturing method are very sensitive to quantity and size of continuous filaments in the web of continuous filaments with which the short fiber layer should integrate. If the continuous filament fabric is too open, there is a risk that the short fibers will leave the material in the tangled stage. This can lead to holes in the material and uneven distribution of the base weight in the material obtained. If the continuous filament fabric is too dense, it is difficult to achieve a good integration of short fibers in the material. The material will then be like a laminate rather than a compound that has a face that predominantly contains short fibers and the other side predominantly contains continuous filaments. In such a material the union of the continuous filaments will be poor and the face that predominantly contains short fibers will be sensitive to abrasion and fraying.

The objective of the present invention is provide a nonwoven composite material containing filaments  continuous and short fibers in which continuous filaments and Short fibers are well integrated in the material and that can be produced using a manufacturing method that is cost effective and by which the integration of the filaments is guaranteed and fibers can be made by matting, without the need for a premix stage of filaments and fibers.

Summary of the invention

This goal is achieved, according to the invention, by a nonwoven composite material in accordance with claim 1. Ensuring that the filament fabric Continuous used in the manufacture of such a material is not neither too open nor too dense, a material can be obtained nonwoven compound consisting of continuous filaments and fibers short in which the filaments and fibers are well integrated, by entangled without a premix stage and with a low consumption of Energy. Said composite material will have similar properties in both sides of it.

In a preferred embodiment the short fibers They comprise natural fibers and / or synthetic short fibers. Preferably, the short fibers comprise at least 60% in weight of cellulose fibers, preferably at least 70% in weight, more preferably at least 75% by weight and more preferably at least 85% by weight. Advantageously, the fibers Shorts comprise 85 to 95% by weight of the cellulose fibers, preferably about 90% by weight. The content of continuous filaments in the material is preferably approximately 25-40% by weight. Base weight of the material is 40-100 g / m2, preferably 50-80 g / m2 and the short fibers are preferably wet laid fibers.

The invention also relates to a method for manufacture a nonwoven material according to claim 8.

In a preferred embodiment the energy input in the hydroentangling is at least about
500 kWh / ton, preferably approximately 300-400 kWh / ton and more preferably approximately
350 kWh / ton

Brief description of the drawing

The invention will be described below with with respect to the attached Figure 1, which schematically illustrates a process line for manufacturing a composite material not tissue according to a preferred embodiment of the method of according to the invention.

Description of realizations

In the illustrated process line schematically in Figure 1, a filament fabric is placed continuous not attached on a conveyor belt 1. The belt Conveyor 1 is air permeable and can comprise, by example, a fabric forming fabric or a thread. Filaments Continuous placed on the transport cloth are supplied by a conventional device 2 to produce filaments yarn

Spun filaments are produced by extrusion of a molten polymer through a row that can have 3000-5000 holes / m wide with a diameter 0.5 mm typical. The extruded polymer is then accelerated by high speed air using a dimmer with grooves extraction or by means of inactivation air. The dimmer with Extraction slots works like a wide ejector and feeds with compressed air that is released in a narrow gap giving as result a very high air velocity (10000-20000 m / min). Speeds can be obtained of very high filaments up to 6000 m / min. As the filaments are extracted by inactivation air in a system closed, the air velocity increases by narrowing the dimming chamber width. By this procedure filament speeds of up to 4000 m / min can be obtained. After the filaments have left the dimmer with slots of extraction or the narrowest passage in the inactivation chamber, the filament speed decreases and they are aspirated and deposited on the transport fabric 1. The production of non-woven fabrics Spinning is described in patents, such as US-A-5,389,202, US-A-4,340,563 and US-A-3,692,618.

When continuous filaments are supplied to the transport fabric 1 normally has a diameter of 10-50 µm. The continuous filaments are they supply the transport fabric at a higher speed than the speed of the transport fabric, for example the speed of the filaments is 2000-4000 m / min and the speed of The transport fabric is 100/300 m / min. This means that filaments will form irregular loops and fold over the fabric of transport so that a randomly assigned fabric 4 is obtained of continuous filaments.

Under the permeable transport fabric 1 se it has a suction box 3, so the filaments are will remove in front of the transport fabric by aspiration provided and the continuous filament fabric will assume an appearance more or less two-dimensional, that is, that the loops or folds of the upright strands of the transport fabric in the supply from it will be stretched by aspiration to a position horizontal or almost horizontal.

It is essential for the present invention that filaments that are continuous in the transport fabric are not united and can move freely with respect to each other.

Preferably, the filaments comprise polypropylene or polyesters but may also comprise other polymers, such as polyethylene or polyamides and polyacids. Too copolymers of these polymers can be used, as well as natural polymers with thermoplastic properties. In principle it is possible to use all thermoplastic polymers.

Continuous filament fabric 4 advances subsequently to a device 5 to wet a layer  6 short fibers on the filament fabric 4. This device It is also of conventional construction.

The short fiber fabric 6 comprises preferably natural fibers, preferably cellulose fibers  or a mixture of natural fibers and short fibers. Fibers of cellulose are preferably wood pulp fibers but it is possible to use any type of cellulose fibers such as grass or straw. Also suitable are softwood fibers and hardwood fibers. Short fibers can be fibers synthetics made of the same materials as the filaments continuous and, of course, the copolymers of these can be used materials. It is also possible to use renewed cellulose fibers such as rayon and liocel.

Short fibers must comprise at least the 60% by weight of cellulose fibers, preferably at least 70% by weight, more preferably at least 75% by weight and even more preferably at least 85% by weight. Advantageously, the fibers Shorts comprise 85-95% by weight of fibers of cellulose, preferably about 90% by weight.

The fabric 4 of continuous filaments in layer 6 of fibers arranged on it then advances towards a hydroentangled device 7. In this device, various high pressure water jet distribution manifolds, such as 50-120 bars, they are directed against the layer of 6 fiber and 4 filament fabric. During this stage the fibers and filaments will mix and tangle with each other, with other fibers and with filaments.

Finally, the mixed nonwoven material obtained in the entangled stage advances towards a device of drying 8. This device can be of conventional construction, such as an air pass dryer.

As stated above it is essential for the present invention that continuous filaments in the fabric 4 are not linked together. Unbound means that continuous filaments in the web 4 are free to move around with with respect to others, that is, the possible adhesions of filaments with each other due to possible permanent adhesives when the filaments are arranged on the transport fabric 1 are so weak that such possible adhesions will break when the Filaments collide with water jets. A great advantage of use of a layer of unbound continuous filaments is that the matting can be done with low energy consumption in the hydroentangling stage compared to the energy consumption of  a layer of continuous filaments thermo bonded together. This is because to the fact that unbound filaments are easy to move around the water jets compared to the united filaments, whose movements will usually involve movements of other filaments attached to them. The energy input in the matting is in the present invention at most about 500 kWh / ton, preferably about 300-400 kWh / ton and more preferably about 350 kWh / ton. The contribution of energy in the hydroentangling is calculated as the flow product of water (l / min) and pressure during matting (bar) divided by the amount of material produced per hour (kg / h).

Another reason for using a filament layer continuous unbound in the present invention is that it has proved that it is very difficult to get an integration good enough of short fibers and continuous filaments with a layer of continuous filaments attached even if several are used entangled stages. This probably occurs by the steps between the joined parts of the adjacent filaments that occupy very Quickly short fibers that prevent the penetration of short fibers through the last layer of filaments during the matting process. The known use of a filament layer continuous together therefore has a tendency to produce nonwoven compounds with a double face or so pronounced

The links between the fibers and filaments in a nonwoven material manufactured by the process described previously they will be mainly mechanical links due to entangled fibers and filaments. However, in the material the hydrogen bonds between cellulosic fibers will be present.

When a fabric of unbound filaments is used as a basis for a nonwoven material, the integration of the two layers, that is, the continuous filament fabric 1 and the layer of fiber 6, is however very critical. If both layers are not right integrated, this material will also have a pronounced appearance of two faces and the union of continuous filaments will be poor. Saying material will have a reduced resistance, especially in the thickness direction. The short fiber face of said material of two sides will have high fraying, that is, a tendency to lose the short fibers of the material. The face links of short fibers will predominantly comprise links between fibers short and the resistance of the material on the fiber face Shorts will be scarce. The face of filaments of said material will be sensitive to "ball formation" when it wears out, it is that is, parts and ends of filaments that will have a tendency to protrude from the surface of the filament face of the material. A nonwoven composite material that contains short fibers and continuous filaments only joined by matting, in which the integration of short fibers and continuous filaments has failed to some extent, it will have worse properties than a material similar that contains short fibers and continuous filaments attached before each other before the matting stage.

When the matting stage begins the 4 layer structure of continuous filaments opens relatively and it is easy for water jets to move the fibers cut in layer 6 overlapping with the filaments in the layer of filaments across the width of it. The more fibers Shorts move in the filament layer, the less space there will be available for easy transport of the remaining short fibers over the top of the filament layer. But nevertheless, due to the low resistance with respect to the movement of the filaments caused by the absence of links between them when enter the tangled station, the duration of the period of matted in which short fibers can move in the layer of filaments increases compared to the period for a layer of filament previously attached. The mixture of short fibers and filaments continuous therefore will occur mainly in the principle of the tangled stage. During the rest of the matting stage, the parts of the filaments and the parts of the short fibers are they will entangle, entwine and twist each other and with filaments and / or other fibers. It can therefore be said that the matted contains a mixing stage followed by a stage of Union. Of course, during the mixing stage there will be some union but most unions will be obtained after the Short fibers have been mixed with continuous filaments.

Even if using a layer 4 of filaments unbound continuous facilitates integration between short fibers and the continuous filaments, a two-sided material can be obtained if the continuous filament layer is too dense.

On the other hand, if the structure of layer 4 of continuous filaments is too open, there is a risk that the fibers leave the material through the water jets during matted. This could create holes in the material and a unequal distribution of base weight.

The inventors have discovered that to obtain a nonwoven composite material in which both layers 4 and 6 are well integrated and have a high resistance and a homogeneous base weight distribution, the filament fabric continuous should have a projected coverage of between 1.3-1.6.

The projected coverage is the sum of the area projected surface of all filaments in a unit area and is obtained by multiplying the sum of filament lengths in a unit area with the average diameter of the filaments. The filaments in a web of continuous filaments that have a Projected coverage of 1.0 may cover the entire unit area if they will be placed in a layer in straight lines adjacent to each other and in a Cape.

Table 1 shows the resistance to Taber abrasion as a function of the projected coverage to the nonwoven material produced as described above with respect to Figure 1. Nonwoven materials are 80 gsm spun composite materials comprising 25% (20 gsm) of continuous spun polypropylene filaments and with or without 10% pulp fibers 19 mm long, 1.7 short fibers  Polyester dtex mixed inside. Materials not Fabrics were manufactured as follows. A 0.4 m fabric width of spun filaments was arranged on a molded fabric to 20 m / min so that the filaments do not join together. Through a 0.4 m wide head box a fiber dispersion that contains pulp fibers and short fibers or alternatively without Short fibers were laid on unbound filament tissue yarn and excess water was extracted and adsorbed. Filaments unbound yarn and short wet fibers then mixed and joined together by hydroentangled with three collectors at a hydro-entangled energy of approximately 300-350 kWh / ton. The hydroentangling was performed from the wet lying face and the pulp and short fibers are then moved in and mixed intensively with the spun filament fabric. Finally, the composite material does not hydroentangled yarn was dehydrated and then dried using a drum dryer with air passage.

Only examples that show a projected coverage between 1.3-1.6 and a content of continuous filaments of approximately 15-40% in Weight are included within the scope of the claims.

Taber resistance values refer next to the pulp of the nonwoven composite material.

TABLE 1

one

As is evident from Table 1, the Pulp side resistance is optimized to cover projected between 1.3 and 1.5 corresponding to a filament title of 3.2 and 2.5 dtex (g / 10000 m), respectively. A cover projected higher than 1.7 or more represented by coverage 1.7 and 2.1 projected correspond to filament titles of 1.9 and 1.3 dtex, respectively, the integration or mixture of fibers and filaments in the material was not good, giving as result a very poor surface resistance on the side of the material pulp. At projected coverage less than 0.9 corresponding to a filament title of 6.9 dtex, the structure of the filament tissue becomes too open to hold the pulp and the surface resistance of the pulp side is It is poor.

Taber's abrasion resistance is measured using the Taber 5151 test set with two rubber wheels CS-10 Those skilled in the art know this well. equipment and it is not necessary to describe it in detail. The essay is performed by assembling a circular test sample in the non-material tissue on a rotating disk in the Taber test set. In this test, the test sample is subjected to the pressure of the two rubber wheels that roll on the upper surface of the test sample. Depending on the sample base weight of the test the disc rotates at a different speed, increasing the number of revolutions with increasing base weight of the test sample. The Taber value of the tested sample is determined by visual comparison with a scale, that is, five reference samples that have Taber values from 1 to 5, in the that 1 defines a very poor abrasion resistance and 3 defines a acceptable abrasion resistance.

Table 2 shows the Taber values of three nonwoven materials, manufactured as described previously, they have different base weights and contain continuous filaments Continuous filaments are filaments Polypropylene yarns and short fibers are pulp fibers. He Taber value in the table represents the average of two samples identical test.

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TABLE 2

2

From Table 2 the conclusion of that if the projected coverage is between 1.1 and 1.6, they can provide well integrated nonwoven composite materials to nonwovens with a basis weight of 80 g / m2 or more. For nonwovens that have a lower base weight the projected coverage will be at less than 1.2 to provide acceptable material. At range of 1.3-1.6 nonwovens are provided acceptable even for nonwovens with a lower base weight and high content of continuous filaments. Therefore, when they construct nonwoven materials according to the invention the ideal projected coverage is between 1.3-1.6.

The following examples show the important which is to select the correct filament title to get the ideal projected coverage as base weight and / or spinning content varies in a composite material laid in wet-spinning

Tables 3-5 show the filament title for three different base weights, 50, 80 and 100 gsm, as a function of the spinning content and the coverage.

The calculation is performed as indicated by continuation:

The projected coverage (VOC) is obtained dividing the projected surface area (A_ {projected}) of all spun filaments within a unit area with the corresponding unit area (A) according to the following equation.

4

The projected surface area is obtained multiplying the total length (L) of all spun filaments with the average diameter (d) in m of all spun filaments within the unit area.

5

The total length of the filaments within the unit area is obtained by dividing the total weight of the filaments yarns with the average filament title (Title) in dtex as shown in equation (3) below. The weight of the spinning filament fabric is obtained by multiplying the basis weight of the spun filament fabric (BW_s) in g / m2 with area unitary (A). The title of the filament in dtex is the weight of the filaments corresponding to 10 000 m, that is, g / 10 000 m.

6

For the wet laid composite material, the base weight of the spun filaments is calculated by

7

where [BW] is the basis weight of the wet spun compound in g / m2 and (X) is the content of the spun filaments in%.

L is therefore:

8

The relationship between the Title in dtex and the diameter in m of the filaments is given below in the that (\ rho) is the specific gravity of the filaments in kg / m 3.

9

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How (d) is solved from equation (6) Previous the relationship for the title is:

10

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If equations (2), (5) and (7) are used in (1) Projected coverage is provided by:

eleven

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When equation (8) is coverage Simplified projected is provided by:

12

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If the title is solved by the equation (9) above you get the relationship between the title, the coverage projected, base weight and spinning content.

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The specific gravity for polypropylene is approximately 900 kg / m2 for polyester approximately 1350 kg / m 3.

In Tables 2-4 below filament title for coverage interval is shown ideal projected ie between 1.3 and 1.5 for materials wet-spun compounds. I also know shows the filament title of the external interval when the spun tissue opens or densifies to form a material spun-wet compound acceptable for projected spun coverages corresponding to 1.1 and 1.7.

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TABLE 3 Filament title in dtex based on content spinning and covering for a composite material laid in wet-spun 50 g / m2

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TABLE 4 Filament title in dtex based on content of spinning and covering for a spun composite wet laying of 80 g / m2

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TABLE 5 Filament title in dtex based on content of spinning and covering for a spun composite 100 g / m2 wet lay

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How the filament title in the Tables is compared it is clear that for composite materials wet-spun yarns with high base weights and / or high yarn contents a greater title of spun filaments to obtain the coverage projected by ideal yarn. When composites are prepared wet-spun yarns with a low base weight and / or low yarn contents should be used a smaller title of the spun filaments to obtain the projected spun coverage ideal.

The results in the Tables also show that as the spinning content in the materials changes with a relatively small percentage, a greater filament title adjustment to maintain coverage projected by spinning at the same level. Similarly, a change relatively small of the total base weight of the material requires a relatively large filament title setting to be able to achieve the coverage projected by ideal spinning.

As the projected coverage is the product of the length of the filament and the average diameter of the filaments, the ideal projected coverage can be obtained by varying the length of the filament / m2, that is, the speed by which the filaments are arranged on the transport fabric 1 or the diameter of the filaments. Therefore, it is relatively easy for a subject matter expert adapt process parameters within The limits given.

Claims (9)

1. A nonwoven composite material comprising a mixture containing continuous spun filaments and short fibers characterized in that in the material there are no thermo links between the continuous filaments, the continuous filaments being substantially mechanically bonded together due to the entanglement of fibers and filaments and because the continuous filaments in the material have a projected coverage between 1.3-1.6, said projected coverage being the sum of the projected surface area of all the filaments in a unit area, the content of continuous filaments in the material being approximately 15-40% by weight. 2. The nonwoven composite material according with claim 1, wherein the short fibers comprise natural fibers and / or synthetic short fibers. 3. The nonwoven composite material according with claim 2, wherein the short fibers comprise the less than 60% by weight of cellulose fibers, preferably at least 70%, more preferably at least 75% by weight and even more preferably at least 85% by weight. 4. The nonwoven composite material according with claim 3, wherein the short fibers comprise the 85-95% by weight of cellulose fibers, preferably about 90% by weight. 5. The non-woven composite material according with any one of claims 1-4, in the one that the content of the continuous filaments in the material is approximately 25-40% by weight. 6. The nonwoven composite material according with any one of claims 1-5, in The base weight of the material is 40-100 g / m2, preferably 50-80 g / m2. 7. The nonwoven composite material according with any one of claims 1-6, in that short fibers are wet laid fibers. 8. A method for manufacturing a nonwoven material characterized by the steps of placing a web of continuous unbound spun filaments (4) on a transport cloth (1) and selecting the speed at which the filaments are placed on the web of transport (1) and the diameter of the filaments so that the web (4) of unbound continuous filaments has a projected coverage of approximately 1.3-1.6, said projected coverage being the sum of the projected surface area of all filaments in a unit area, wet or lay a layer of short fibers (6) on the fabric of unbound continuous filaments (4) in such an amount that the content of continuous filaments in the material is approximately 15- 40% by weight, hydroentangle the layers comprising continuous filaments and short fibers to form a nonwoven composite material and subsequently dry the material. 9. The method according to claim 8, in which the power supply in hydroentangling is, as maximum, approximately 500 kWh / ton, preferably approximately 300-400 kWh / ton and more preferably approximately 350 kWh / ton.