SE467499B - PROCEDURES FOR HYDROENT ANGLING - Google Patents

Description

10 15 20 25 30 35 467 499 2 concentration of one type of fiber on one side and one higher concentration of the second type of fiber on the other side.

When the formed fiber mat consists of a homogeneous mixture of two types of fiber, however, a homogeneous material is formed.

It has been found that if dry-defibrated pulp is used. fibers together with staple fibers can be a strong spunlace material is formed with a relatively small energy input at one tanglingen. However, material integrity does not remain the same degree built at this energy input. This means that the staple fiber side is easily roughened up when using the material and even after a slight abrasion gives one such material a fuzzy impression. For some disposable materials, for example, those to be used in operating rooms or for wiping, they are required not to give in use emit lint or particles. A two-sided material, which one side of the ket exhibits the above-mentioned weak abrasion resistance, can therefore not be used for these areas of application. For to reduce the two-sidedness and fuzziness of such a material, you can let the entanglement take place with greater energy input, which, however, considerably increases the cost of manufacturing the material in question.

The present invention aims to increase the abrasion resistance and thus increase the bond between the fibers in the staple fiber side of a spunlace material, which is made from a formed fiber mat composed of a lower layer of air-laid staple fibers and a superimposed layer of pulp fibers, any significant increase in energy input during entanglement.

This object is achieved according to the invention by initiating The process mentioned for hydroentangling is characterized of the following steps; ' the formed fiber mat is subjected to a first entanglement on a fine-mesh wire, 10 15 20 25 30 35 467 499 3 the entangled fiber mat is subjected to a second entanglement on a coarse-mesh virus, the single fiber mat is transferred one after the other the entanglement into a fine-mesh wire and exposed to one third entangling.

By transferring it for the first entanglement with high press the exposed fiber mat into a wire with much finer meshes are folded from the underside of the fibrous mat projecting fibrous ends towards this underside and the subsequent entanglement causes these fiber ends to be firmly bonded to the fibers in the fiber mat. Abrasion resistance is increased by these fiber ends are bonded to the underside. Furthermore, these form bonded fiber ends a network on the underside of the staple fiber side of the material, which network reduces the risk of existing fiber ends in the material shall protrude at the reversal of this.

In a preferred embodiment of the invention, each the similarity of the second entanglement so that an appropriate number of fiber ends protruding through the underlying wire.

Thus, utilized and even enhanced by finding the undesirable uptake in conventional entangling the emergence of fiber ends projecting through the entangling wire.

Through the finesse of it at the first entanglement used wire, the smoothness of the fiber mat is maintained during the tangling and the staple fibers and the wire form together a very nice network, which prevents them short the pulp fibers are rinsed out of the fiber mat.

An embodiment of the method according to the invention shall now described with reference to the accompanying drawing, which schematically shows the transfer of the fiber mat from the other to the third entangling wire.

In the working example, 1.5 deniers dry defibrated were used pulp fibers with an average length of 2.5 m. These fibers 10 15 20 25 30 35 467 499 4 laid on top of a layer of staple fibers, which examples can consist of PES, viscose, 0.8-2.2 dtex and 20-60 mm long, which are air-laid on a forming wire by means of a conventional staple fiber former, such as a Curlator, Randow ebber, Ferrer K12, etc. For the aeration of pulp fibers can a Danwebb type, Krçyert type or other pulp fiber former conventional type can be used.

'IN The formed fiber mat is transferred to a fine mesh first single wire with a thickness of 100 mesh and single glass. Through using a fine-mesh wire at this stage preserves the smoothness of one of the undersides of the formed fiber mat during entanglement. one. Furthermore, the fine wire together with the stacking the fibers a very fine three-dimensional network, which prevents the short pulp fibers from being rinsed out of the fiber the carpet at the entanglement.

The equipment used in the entangling is commercial available and marketed by Honeycomb Systems Inc. or Perfojet S.A.

After the first entanglement, the fiber mat is transferred to it second entangling wire with a thickness of 60 mesh and less opening area and entangled again. The through the previous entanglement effect the bonding between the fibers in the fiber the mat ensures that the pulp fibers on the pulp fiber side of the fiber mat is not carried away by the water jets and that not to a significant extent there are unbound, short mass fibers, which by the water jets can be passed through it relatively the coarse structure of the fiber mat and rinsed out through the coarse maskiga viran. However, the water jets will push loose fiber ends through the coarse meshes in the wire. This takes place to a large extent at the beginning of the second entanglement then the fiber mat has a relatively open structure. : q "1 In the case of entanglement with only fine wires, a com- compaction of the fiber mat, which in step with the compaction gets an increasingly dense structure. Thereby come the fiber parts, which at the beginning of the entanglement with high pressure significantly affected 10 15 20 25 35 467 499 5 in the vertical direction of the water jets increasingly that affected in the horizontal direction due to the fact that the vertical the tin beams are increasingly deflected and split up in the horizontal direction by hitting tightly bound fiber in the fiber mat or the threads in the wire. Thus increases the strength of the fiber mat very quickly at the beginning of the entanglement with high pressure and after a certain time no appreciable thing happens increase in the total strength of the fiber mat. One after this time continued entanglement to ensure the attachment of standing fiber end projecting through the wire therefore provides a small yield in terms of strength increase for the material in its as a whole and therefore requires a large energy investment in to provide an abrasion resistant in this way staple fiber side of a double-sided nonwoven fabric. In addition the fine wire itself entails a limitation of the energy input per unit of time due to limited drainage capacity.

According to the invention, the abrasion resistance of one is achieved completely different way while maintaining a low energy input at entang- lingen. This is achieved by separating the second entanglement is broken before the fiber mat has reached full strength and through that the fiber mat is then transferred to a third very fine mesh entangling wire with a thickness of 100 mesh. At this transmission, they come from the underside of the fiber mat free fiber ends to be folded towards the bottom of the fiber mat side and due to the fineness of the wire, the folded fiber the ends along most of their length are also kept printed towards the underside. The to the third entangling wire transferred the lined fiber mat is then subjected to a second entanglement with high pressure, at which the folded fiber ends can be easily twisted fixed to the fiber mat by those appearing at the entanglement the water vortices. In the figure, they are denoted by the second unit. tanglingen use the wire's transverse threads with 1 and the at the third entanglement use the transverse threads of the wire with 2. The distances between the wires of these wires are denoted by a resp. b.

Time of transfer from the second to the third the entangling wire is not particularly critical. About the transfer 10 15 20 25 30 35 467 499 6 for example, takes place before the maximum number of obtained in the second entanglement will still be a nut- resistant staple fiber side to be obtained after the third the singularity provided that the number from the other the entangling wire downwardly projecting fiber ends is not too much small. There will be no new downward-sloping fiber ends occur at the subsequent third singular because it fine mesh wire together with the folded fiber ends and the outer layer of the underside of the fiber mat forms a very fine three-dimensional network. If the transfer takes place slightly after that the maximum number of downwardly projecting fiber ends has been obtained at the first high-pressure entanglement has the number of sliding fiber ends have not had time to decrease to such an extent that the abrasion resistance after the third entanglement becomes reduced. However, in view of the energy input, it is preferred that the transfer to the third entangling wire takes place before maximum number of downwardly projecting fiber ends has been formed. Therein- through the third entangling is also used to give one significant contribution to the overall build-up of the lacing material. According to a preferred variant of the invention therefore, the transfer to it takes place third entanglement wire when an "appropriate number" of fiber ends have been formed. By "appropriate number" is meant one sufficient number to required abrasion resistance of the staple fiber side shall arise after the third entanglement lingen. This appropriate number is suitably determined empirically.

In the invention it is used in conventional entangling disadvantageous phenomenon that fiber ends shoot down through a tangling wire to increase the abrasion resistance of the the pile fiber side of the fabricated spunlace material. If there- at the number of downwardly projecting fiber ends is large enough comes after the third entangling a very fine network to be formed on the staple fiber side by the folded mass the fiber ends are firmly connected to the fibers of the fiber mat underside. This network prevents the above free fiber ends in the fiber structure from penetrating when using a spunlac material made in accordance with the invention. 10 15 20 25 30 35 467 499 7 The thickness of the second entangling wire is crucial especially for the length of the fiber ends, which after it the first high pressure entanglement will protrude through the other entangling wire. If the mesh size of the wire is for small prevents the network that the wire together with the surface the lower part of the underside of the fiber mat forms, that an sufficient number of downwardly projecting fiber ends of sufficient length arises. With large mesh sizes, there is a risk of holes or irregularities occur in the fiber mat.

With the fibers used in the working example, a wire was found of 60 mesh, be suitable. Average length, 2.5 mm, off the pulp fibers were thus about six times larger than the mesh width. one.

The third entangling wire had a fineness of 100 mesh.

A total of 500 kWh / ton was used in the entangling, of which one third was used for each entanglement step.

It will be appreciated that the coarseness of the vials used in the entanglement the tubes must be adapted to the nature of those in the fibrous mat constituent fibers for a satisfactory result shall be obtained. For the fibers which may be used in the use of the method according to the invention, can be good results are achieved by an appropriate combination of viruses within the 80-100 mesh range for the first entangling wire, 40- 80 mesh for the second single wire and 100-200 mesh for the third entangling virus.

Thus, it is achieved by the method according to the invention that a spun laser material useful in operating rooms can be produced with a significantly lower energy input than before known entangling methods starting from a fiber mat, formed by aerating pulp fibers on top of one aerated layer of staple fibers. By means of the invention, the effect is also carried out with less material waste than before.

Claims (7)

n 10 15 20 25 -30 35 A 6749 1 8 Patent claim A method for hydroentangling a mixture of staple fibers and pulp fibers, which fibers are formed on a forming wire with the pulp fibers laid on top of the staple fibers, characterized by the following steps; the formed fiber mat is subjected to a first entanglement on a fine mesh wire, - the entangled fiber mat is subjected to a second entanglement on a coarse mesh wire, - the entangled fiber mat is transferred after the second entanglement to a fine mesh entanglement wire and is subjected to a third entanglement. 2. A method according to claim 1, characterized in that the wire used in the first entanglement has coarser meshes than the wire used in the third entanglement. 3. A method according to any one of claims 1-2, characterized in that the second entanglement is interrupted when a suitable number of fiber ends protrude downwards from the coarse-mesh entangling wire. 4. A method according to any one of claims 1-3, characterized in that the pulp fibers are on average six times longer than the width of the meshes in the wire used in the second entanglement. A method according to any one of claims 1-4, characterized in that the coarseness is 80-100 mesh of the wire used in the first entanglement, 40-80 mesh of the wire used in the second entanglement and 100-200 mesh of the wire used in the third entanglement. Method according to one of Claims 1 to 5, characterized in that the formed fiber mat contains 20-80% of dry-defibrated 1.5 denier pulp fibers and the remainder staple fibers, 0.8-2.2 dtex. and 20-60 mm long. Method according to one of Claims 1 to 6, characterized in that the energy input at entanglement is approximately 500 kWh / ton.