MXPA00003946A - Method of manufacturing a nonwoven material - Google Patents

Abstract

Method of producing a nonwoven material by hydroentangling a fiber mixture containing continuous filaments, e.g. meltblown and/or spunbond fibers, and natural fibers and/or synthetic staple fibers. The method is characterized by foamforming a fibrous web (14) of natural fibers and/or synthetic staple fibers and hydroentangling together the foamed fiber dispersion with the continuous filaments (11) for forming composite material where the continous filaments are well integrated with the rest of the fibers.

Description

METHOD OF MANUFACTURE OF A NON-WOVEN MATERIAL BACKGROUND OF THE INVENTION The present invention relates to a method of producing a non-woven material by hydroentangling a mixture of fibers containing continuous filaments and natural fibers and / or short, synthetic fibers. Hydroenvelopment or spinning is a technique introduced during the 1370s, see, for example, CA Patent No. 841 938. The method includes forming a fiber web that is dry-laid or wet-laid, after which fibers are entangled by means of very thin jets of water at high pressure. Some lines of water jets are directed against the fiber veil that is supported by a moving wire. Then the veil of entangled fibers is dried. The fibers that are used in the material may be synthetic or regenerated, short fibers, for example polyester, polyamide, polypropylene rayon or the like, pulp fibers or mixtures of pulp fibers and staple fibers. Yarn interlaced materials can be produced in high quality at a reasonable cost and have a high absorption capacity. These can, for example, be used as cleaning material for domestic or industrial use, as disposable materials in medical care and for hygiene purposes, etcetera.

In WO 96/02701 the hydroentangling of an expanded fibrous web or formed by foam is described. The fibers included in the fibrous hair can be pulp fibers and other natural and synthetic fibers. Through, for example, EP-B-0 333 211 and EP-B-0 333 228 it is known to hydroentangle a mixture of fibers in which one of the component fibers is meltblown fibers. The base material, that is to say, the fibrous material that is occupied for the hydroentanglement, consists of at least two preformed fibrous layers, where a layer is composed of blown fibers of fusion or of a "material coform" where an essentially homogeneous mixture of the blown fibers of fusion and other fibers are placed in air on a wire and then the hydroentanglement is exerted. Through EP-A-0 308 320 it is known that by joining a web of continuous filaments with a fibrous material placed in wet containing pulp fibers and staple fibers and hydroentangling together the fibrous webs formed separately in a laminate. Such fiber material of the different fibrous webs will not be integrated with each other since the fibers during hydroentangling are bonded together and have only very limited mobility.

Most important object and characteristics of the invention The object of the present invention is to offer a method for producing a hydroentangled nonwoven material of a fibrous blend of continuous filaments, for example, in the form of meltblown and / or spunbond fibers and natural fibers and / or staple fibers, where high freedom is given in the choice of fibers and where the continuous filaments are well integrated with the rest of the fibers. This, according to the invention, has been obtained by foam forming a fibrous web of natural fibers and / or staple fibers, synthetic and hydroentangling together the dispersion of foamed fibers with the continuous filaments to form a composite material, where the continuous filaments are well integrated with the rest of the fibers. Through the formation of foam an improved mixing of the natural and / or synthetic fibers with the synthetic filaments is obtained, the mixing effect is reinforced by the hydroentangling, so that a composite material is obtained in which all types of fibers are mixed in a manner that is almost homogeneous with each other. This, among other things, is demonstrated by the very high strength properties of the material and by a wide distribution in the pore volume.

DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below with reference to some embodiments shown in the attached drawings. Figure 1-5 shows schematically different embodiments of devices for producing a hydroentangled nonwoven material according to the invention. Figure 6 and 7 shows the distribution of the pore volume in a reference material in the form of a spin-entangled material, formed by foam and a spin-entangled material consisting only of meltblown fibers. Figure 8 shows the distribution of the pore volume in a composite material according to the invention. Figure 9 shows in the form of a diagram of staple fibers the tensile strength in the dry and wet state and in a tenside solution for the composite material and for the two base materials included therein. Figure 10 is an electron microscope image of a material not produced in accordance with the invention.

Description of some embodiments Figure 1 shows as schematic a device for producing a hydroentangled composite material according to the invention. A gas stream of melt blown fibers is formed according to the conventional melt blowing technique by means of a blow molding equipment. fusion 10, for example, the class shown in US Patents 3,849,241 or 4,048,364. The method, shortly, includes that a molten material is extruded through a nozzle in very fine streams and converging air currents are directed towards the polymer streams so that these are drawn into continuous filaments with a very small diameter. The fibers can be microfibers or macrofibers depending on their size. Microfibers have a diameter of up to 20 μ, but they are usually between 2 and 12 μ in diameter. The macrofibers have a diameter of about 20 μ, for example, between 20 and 100 μ. All thermoplastic polymers can, in principle, be used to produce blown fused fibers. Examples of the useful polymers are polyolefins such as polyethylene and polypropylene, polyamides, polyesters and polyacids [sic]. The copolymers of these polymers can of course also be used, as well as natural polymers with thermoplastic properties. Spunbond fibers are produced in a slightly different way by extruding a molten polymer, cooling it and stretching it to a suitable diameter. The diameter of the fiber is usually above 10 μ, for example, between 10 and 100 μ. The continuous filaments in the following will be described as meltblown fibers, but it is understood that it is also possible to use other types of continuous filaments, for example spunbonded fibers. According to the embodiment shown in Figure 4, the meltblown fibers 11 are placed downwardly directly on a wire 12 where they are allowed to form an open, relatively loose veil structure in which the fibers are relatively free each. This is achieved by making the distance between the meltblowing nozzle and the relatively large wire, so that the filaments are allowed to cool before they are placed on the wire 12, in which their tackiness is reduced. Otherwise, the cooling of the blown fibers of the melt before they are placed on the wire is achieved in some other way, for example, by means of spraying with liquid. The basis weight of the blown layer of the melt, formed_ should be between 2 and 100 g / m 2 and the mass between 5 and 15 cm3 / g. The fibrous web formed by foam 14 of a head box 15 is placed on top of the meltblown layer. Foaming means that a fibrous web is formed of a dispersion of fibers in a foamed liquid containing water and a tenside. The foaming technique is described, for example, in GB 1,329,409, US 4,443,297 and in WO 96/02701. A fibrous web formed by foam has a very uniform fiber formation.

For a more detailed description of the foaming technique reference is made to the aforementioned documents. Through the effect of intense foaming already at this stage will occur a mixing of the meltblown fibers with the dispersion of foamed fibers. The air bubbles of the intense turbulent foam emerging from the head box 15 will penetrate downwards between and push the mobile meltblown fibers, so that the somewhat thicker foam-formed fibers will be integrated with the blown melt fibers. Thus, after this step, there will be mainly an integrated fibrous web and no more layers of veils of different fibers. Fibers of many different types and in different mixing ratios can be used to make the fibrous web formed by foam. Thus, it is possible to use pulp fibers or mixtures of pulp fiber and synthetic fibers, for example, polyester, polypropylene, rayon, lipocel, etc. As an alternative to synthetic fibers, it is possible to use natural fibers with a long fiber length, for example, above 12 mm, such as fibers of seed hairs, for example, cotton, apok, and asclepiadeae; leaf fibers, for example, henequen, abaca, pineapple, New Zealand hemp, or phloem fibers, eg, flax, hemp, ramie, jute, hemp variety. It is possible to use different lengths of the fibers and by the technique of foam formation it is possible to use fibers longer than what is possible with the conventional wet laying of the fiber webs. The long fibers, ca. 18-30 mm, is an advantage in hydroentanglement, since they increase the resistance of material in dry as well as wet state. Another advantage with foaming is that it is possible to produce materials with a lower basis weight than possible with wet laying. As a substitute for pulp fibers it is possible to use other natural fibers with a short fiber length, for example, esparto grass, phalaris arundinacea and straw from the crop seeds. The foam is sucked through the wire 12 and down through the veil of the blown melt fibers placed on the wire, by means of suction boxes (not shown) arranged under the wire. The integrated fibrous web of the meltblown fibers and other fibers are hydroentangle while still supported by the wire 12 and with the same shape a composite material 24. Possibly the fibrous web can be - prior to the hydroentanglement to be transferred to a wire for special entanglement , which can possibly be designed to form a nonwoven material with design. The entanglement station 16 may include some rows of nozzles from which very thin water jets under very high pressure are directed against the fibrous web to provide an entanglement of the fibers. For another description of hydroentanglement, or as it is also called, the spinning entanglement technique is referred to, for example, Patent CA 841,938. The meltblown fibers thus before hydroentanglement will be mixed with and integrated with the fibers in the fibrous web formed by foam due to the foaming effect. During the subsequent hydroentanglement, the different types of fibers will be entangled and a composite material is obtained in which all types of fibers are mixed in a virtually homogeneous manner and are integrated with each other. The mobile, fine melt blown fibers are easily twisted and entangled with other fibers which provides a material with a very high strength. The supply of energy necessary for hydroentanglement is relatively low, that is, the material is easily entangled. The power supply in the hydroentanglement is approximately in the range of 50-300 KWh / ton. The embodiment shown in Figure 2 differs from the previous one by the fact that a layer of preformed tissue or gauze or spin-entangled material 17, i.e. a hydroentangled nonwoven material, is used, in which the blown fibers of fusion 11 are placed, after what wherein the fibrous web formed by foam 15 is placed on top of the meltblown fibers. The three fibrous layers combine due to the foaming effect and are hydroentangled in the entanglement station 15 to form a composite material. According to the embodiment shown in Figure 3, a first fibrous web formed by foam 18 is placed on the wire 12 from a first head box 19, is placed on the upper part of the fibrous web of the melt blown fibers 11 and finally a second fibrous web formed by foam 20 from a second head box 21. The fibrous web 18, 11 and 20 formed in the upper part of each other are mixed due to the foaming effect and then hydroentangle while they are still Of course, it is also possible to have only the first fibrous web formed by foam 18 and the meltblown fibers 11, and to hydroentangle these two layers together. The embodiment according to Figure 4 differs from the previous one in that the melt blown fibers 11 are placed on a separate wire 22 and the preformed melt blowing web 23 is fed between the two foam forming stations 18 and 20. Of course, it is possible to use a blown fleece veil, correspondingly preformed 23 also in the devices shown in Figure 1 and 2, where the foaming is performed alone from the upper side of the meltblown veil 23. In accordance with the embodiment shown in Figure 5, a layer of meltblown fibers 11 is placed directly on a first wire 12a, after which a first veil of fibers formed by foam 18 is placed on top of the melt blown layer. The fibrous web is then transferred to a second wire 12b and turned or inverted after which a second fibrous web formed by foam 20 is placed on the "meltblowing side" of the opposite side thereof. The fibrous web is transferred to an entanglement wire 12c and hydroentangle. For purposes of simplicity, the fibrous web in Figure 5 is not shown along the transport portions between the training and entanglement stations. According to another alternative embodiment (not shown) the meltblown fibers are fed directly to the dispersion of foamed fibers, before or in connection with the formation thereof. The mixture of meltblown fibers can, for example, be prepared in the headbox. The hydroentangling is preferably carried out in a known manner from both sides of the fibrous material in which a more homogeneous equilateral material is obtained. After hydroentangling the material 24 dries and it rolls The material then becomes a known form in a suitable format and is packaged.

Example 1 A dispersion of fibers formed by foam containing a mixture of 50% pulp fiber from chemical kraft pulp or sulphate cellulose and 50% polyester fibers (1.7 dtex, 19 mm), were placed in a veil of meltblown fibers (polyester, 5-8 μ) with a basis weight of 42.8 g / m hydroentangled between, yes with them, which resulted in a composite material with a basis weight of 85.9 g / m. The energy supply in the hydroentanglement was 78 kWh / ton. The material was hydroentangled from both sides. The tensile strength in the dry and wet state, the elongation and the absorption capacity of the material were measured and the results are shown in the following table. As reference materials, a fibrous web formed by foam (reference 1) and a meltblown web (reference 2) corresponding to those used to produce the composite material were hydroentangled. The results of the measurement tests for these separate reference materials and placed together for a double layer material are presented in Table 1 below.

Table 1 As can be seen from the results of the previous measurements, the tensile strength in the dry state as well as in the wet state and in the tenside solution was considerably greater for the composite material than for the combined reference materials. This indicates that there is a good mix between the meltblown fibers and the other fibers, which gives rise to an increase in the strength of the material. Figure 9 shows in the form of an ordered variety of fibers the tensile index in the dry and wet state and in tenside solution for the different materials. The total absorption of the composite material is almost as good for the reference material 1, ie, a corresponding spinning interlaced material without mixing the meltblown fibers. On the other hand, the absorption was considerably greater than for the reference material 2, that is, a pure meltblown material. Figure 7 shows the pore volume distribution of the reference material formed by foams, ref. 1, in mm /μ.g, and the cumulative pore volume, normalized in%. It can be observed by the main part of the pores eir the material are in the range of 60-70 μ. In Figure 7 a corresponding pore volume distribution is shown for the meltblown material, ref. 2.

The main part of the pores in this material is below 50 μ. From Figure 8, which shows the pore volume distribution of the composite material according to the above, it can be seen that the pore volume distribution for this material is considerably wider than for the two reference materials. This indicates that there is an effective mixture of fibers in the composite material. A wide pore volume distribution in a fibrous structure improves the liquid absorption and distribution properties of the material and is thus advantageous. It can also be observed from the image of the electron microscope according to Figure 10 showing composite material produced according to the example described above, that the fibers are well integrated and mixed together.

Example 2 _ Different hydroentangled materials with different fiber compositions were produced and tested with respect to tensile strength in wet and dry state, work to breaking and elongation.

Material Dispersion of fibers formed by foam containing 100% pulp fibers from chemical kraft pulp, base weight 20 g / m, was placed on both sides of a slightly compressed layer, very slightly thermoagglomerated of fibers bonded by polypropylene (PP) 1.21 dtex yarn, basis weight 40 g / m, and it was hydroentangled together with them. The tensile strength of the PP fibers was 20 cN / tex, the E modulus was 201 cN / tex and the elongation was 160%. The material was hydroentangled from both sides. The power supply in hydroentanglement was 57 kWh / ton.

Material 2: A tissue layer of chemical pulp fibers was placed on both sides of a spunbonded material, the same as in material A above. The material was hydroentangled on both sides. The power supply in the hydroentanglement was 55 kWh / ton.

Material A fiber dispersion consisting of foam containing 100% pulp fibers from chemical kraft pulp, base weight 20 g / m, was placed on both sides of a slightly compressed, very slightly thermoagglutinated layer of fibers bonded by polyester spinning (PET ) 1.45 dtex, basis weight 40 g / m, and was hydroentangled together with it. The tensile strength of PET fibers was 22 cN / tex, modulus E was 235 cN / tex and elongation 76%. The material was hydroentangled on both sides. The power supply in the hydroentanglement was 59 kWh / ton.

Material 4: A tissue paper layer of pulp fibers (85% chemical pulp and 15% CTMP), with the base weight 26 g / m was placed on both sides of a material bonded by spinning, the same material as in the material To previous. The material was hydroentangled on both sides. The power supply in the hydroentanglement was 57 kWh / ton.

Material 5: A wet fibrous web containing 50% polyester (PET) fibers (1.7 dtex, 19 mm) and 50% chemical pulp fibers was hydroentangled with a power supply of 71 kWh / ton . The base weight of the material was 87 g / m. The tensile strength of the PET fibers was 55 cn / tex, the E module was 284 cN / tex and the elongation was 34%.

Material 6: The same as the previous 5 material - hydroentangled with a considerably higher energy supply, 301 kWh / ton. The base weight of the material was 82.6 g / m. Materials 1 and 3 are composite materials according to the present invention, while materials 2 and 4 are laminated materials outside the invention and should be observed as reference materials. Materials 5 and 6 are traditional hydroentangled materials and should also be seen as references. The energy supply in the hydroentanglement of the material 5 was the same in magnitude as it was used for the entanglement of the materials 1-4 while the energy supply in the hydroentanglement of the material 6 was considerably higher. The results of the measurements are shown in Table 2 below.

Table 2 Table 2 (continued) The results show higher values of "resistance for the composite materials according to the invention- (materials 1 and 3) compared with the corresponding laminated materials (materials 2 and 4) and compared with the reference material placed in wet (material 5) which has been entangled with an equivalent energy supply, especially the values of tensile strength as well as wet, dry and tensile are considerably higher for composite materials according to the invention compared to reference materials. High strength values verify that a composite material with very well integrated fibers was obtained.For the material 6 that had been entangled with a considerably higher energy supply (approximately five times higher) than the composite materials, the tensile strength in state dry is the same level as for composite materials. in wet and tensile, as well as the rate of work at break is still markedly lower than for composite materials. As another comparison, the two layers of spunbonded materials used in the previous tests were hydroentangled. These materials are defined as materials 6 and 7.

Material 7: Two layers of PP joined by spinning, 1.21 dtex, each of base weight 40 g / m, were hydroentangled with an energy supply of 66 kWh / ton.

Material 8: Two layers of PET joined by spinning, 1.45 dtex, each of base weight 40 g / m 2, were hydroentangled with an energy supply of 65 kWh / ton.

The results of the measurements obtained with these materials are shown in Table 3 below.

Table 3 Table 3 (continued) As can be seen, this material has considerably lower strength values in all aspects compared to the composite materials according to the invention. The composite material according to the invention has very high strength values with a very low energy supply in the entanglement. The reason for this is that the homogeneous fiber mixture has been created, in which the synthetic fibers and the pulp fibers cooperate in the fibrous network so that uncommon favorable synergistic effects are obtained. The high values for elongation and work at the break verify that there is a composite material with very well integrated fibers and that they cooperate so that the material can take very large deformations without breaking. The invention is of course not limited to the modalities shown in the drawings and described above but can be modified within the scope of the clauses.

Claims (9)

1. A method of producing a non-woven material by hydroentangling a mixture of fibers containing continuous filaments and natural fibers and / or synthetic staple fibers, is characterized in the foam formation of a fibrous web (14; 18, 20) of natural fibers. and / or cut, synthetic and hydroentangling fibers together of the dispersion of foamed fibers with the continuous filaments (11; 23) to form a composite material (24) where the continuous filaments are well integrated with the rest of the fibers.

2. The method as recited in claim 1, characterized in that the formation of foam occurs directly in a layer of continuous filaments (11; 23) and that the drainage of the fibrous web formed by foam (14) occurs through the filament layer.

3. The method as recited in claim 1, characterized in that a layer of continuous filaments (11) is placed directly on the top of a dispersion of foamed fibers (18) followed by draining of the dispersion of foamed fibers.

4. The method as recited in claim 1, characterized in that a layer of continuous filaments (11; 23) is placed between two dispersions of foamed fibers (18, 20) followed by draining of the dispersions of foamed fibers.

5. The method as mentioned in any of the preceding claims, characterized in that the continuous filaments (11; 23) are placed on a preformed layer (17) of tissue or nonwoven fabric.

6. The method as recited in claim 1, characterized in that the continuous filaments are fed directly to a suspension of foamed fibers before or together with the formation to form the dispersion of foamed fibers. The method as mentioned in any of the preceding claims, characterized in that the pulp fibers are present in the dispersion of foamed fibers. 8. The method as mentioned in any of the preceding claims, characterized in that the continuous filaments (11; 23) are supplied in the form of a fibrous structure type open, relatively loose veil in which the fibers are virtually free from each other , so that they can easily be released to each other and be integrated with the fibers in the dispersion of foamed fibers. 9. The method as recited in any of the preceding claims, characterized in that the continuous filaments are meltblown fibers and / or spunbonded fibers.