SYNTHETIC FIBRES WITH FIBRILS

Abstract: The present invention relates to a method for manufacturing synthetic fibres, comprising of forming a main stem from at least one polymer or polymer mixture and arranging on the main stem fibrils of at least one polymer or polymer mixture. The invention further relates to a nozzle for manufacturing a synthetic fibre with one or more fibrils, comprising a passage for forming a main stem of the synthetic fibre which extends from an inlet of the nozzle to an outlet, and at least one filling space which is connected to at least one moulding chamber for forming the fibrils, wherein the moulding chamber debouches in the passage for forming the main stem.

Description: SYNTHETIC FIBRES WITH FIBRILS The present invention relates to a method and a nozzle for manufacturing synthetic fibres. The invention further relates to synthetic fibres. Synthetic fibres are used in for instance the textile industry to make articles of clothing. A synthetic fibre is generally spun such that a fibre structure is obtained with a smooth surface. Such smooth synthetic fibres have the drawback however that when they are used in for instance articles of clothing they give visibly and tangibly unsatisfactory results. The wearer comfort of clothing manufactured from such synthetic fibres is thus not very great, and the garments look "synthetic". The object of the present invention is to resolve the above stated drawback. This is achieved with the invention by providing a method for manufacturing synthetic fibres, comprising of forming a main stem from at least one polymer or polymer mixture and arranging on the main stem fibrils of at least one polymer or polymer mixture. Synthetic fibres with so-called fibrils are obtained with the method according to the present invention. Making use of synthetic fibres with fibrils according to the invention results in a "woollier" feel when garments are worn which are manufactured from the synthetic fibre according to the invention. Garments manufactured from synthetic fibres according to the invention moreover have a less synthetic appearance. An additional advantage of the method according to the invention is that, compared to conventional smooth synthetic fibres, synthetic fibres manufactured with the method according to the invention have a greater insulating capacity and result in a greater density of materials manufactured from the synthetic fibres due to the many contact points between the synthetic fibres with fibrils and greater air layers between the synthetic fibres. With thermal connection of different synthetic fibres a stronger material is obtained due to the large number of contact points. The synthetic fibres manufactured with the method according to the invention moreover have a higher absorption capacity than smooth synthetic fibres. The surface area of the synthetic fibre is enlarged by the fibrils, whereby a better moisture absorption can be realized. The moisture can also be relinquished easily due to the large surface area. The costs associated with the method according to the invention will also be lower because it is possible to form thicker fibres. Owing to the fibrils these thicker synthetic fibres have the same effect as so- called microfibres which have a lower production efficiency because of their thin diameter. Compared to the conventional synthetic fibres the synthetic fibres manufactured with the method according to the invention further have a better filtering action when they are used for the manufacture of filters, for instance for air and/or water. Owing to the high sound- insulating action of the synthetic fibres according to the invention, comparable to natural fibres such as cotton, they can further also be used in advantageous manner in the acoustic industry. In a preferred embodiment synthetic fibres can be manufactured with the method according to the invention wherein the main stem of the synthetic fibre is manufactured from a first polymer or polymer mixture and the fibrils are manufactured from a second polymer or polymer mixture. Synthetic fibres can thus be produced wherein the main stem and the fibrils consist of different polymers or polymer mixtures. In this way the advantages of a first polymer can be combined with the advantages of a second polymer in one synthetic fibre. Polymers or polymer mixtures with different melting points can for instance be used. The polymer is preferably chosen from the group consisting of polyamide (PA) , polyester (PES) or polypropylene (PP) , or a mixture thereof. Such polymers are particularly suitable for use in for instance textiles, filters and the automobile industry. The invention further relates to a nozzle for manufacturing synthetic fibres with one or more fibrils, which is provided with a passage for forming a main stem of the synthetic fibre which extends from an inlet of the nozzle to an outlet, and at least one filling space which is connected to at least one moulding chamber for forming the fibrils, wherein the moulding chamber debouches in the passage for forming the main stem. Synthetic fibres with fibrils having the stated advantages can be obtained in simple manner in one step with the nozzle according to the invention. Fibrils are created by causing the polymer material to flow at a greater speed through the passage for the main stem than in the filling space and moulding chambers. The placing of an intermittent pressure on the filling space results in an interruption in the supply flow of polymer material in the moulding chamber and fibrils of varying length are created. In a subsequent preferred embodiment the filling space of the nozzle is a space arranged concentrically round the passage for the main stem. In this manner sufficient material is fed via the filling space to the moulding chambers to form fibrils. According to the invention the moulding chamber can debouch at any desired angle in the passage for the main stem. The moulding chamber for forming of the fibrils advantageously debouches in the passage for the main stem at an angle of between 0 and 45°, wherein the angle relates to the angle formed between the main stem and the moulding chamber. Subject to the final application, synthetic fibres with fibrils protruding in differing measure can be manufactured by varying this angle. The filling space is preferably connected to a discharge channel for excess polymer or polymer mixture. Thus is ensured that the polymer/polymer mixture continues to flow and remains in fluid state and excess polymer or polymer mixture is discharged. The present invention finally also relates to a synthetic fibre comprising a main stem of at least one polymer or polymer mixture, and one or more fibrils of at least one polymer or polymer mixture protruding from the main stem. According to the invention the arranged fibrils can have any desired shape and dimensions. The fibrils have the shape of for instance a fish-scale or ear of corn. Such fibrils can be arranged in simple manner and give satisfactory effects. The main stem of the synthetic fibre is preferably manufactured from a first polymer or polymer mixture and the fibrils are manufactured from a second polymer or polymer mixture so that, as already stated, the advantages of a first polymer can be combined with the advantages of a second polymer in one synthetic fibre. The synthetic fibre according to the invention can be manufactured from any suitable polymer or polymer mixture. The synthetic fibre according to the invention preferably consists of a polymer chosen from the group consisting of polyamide, polyester or polypropylene, or a mixture thereof. The synthetic fibres according to the present invention can be manufactured into any suitable type of fibre. Depending on the final application of the synthetic fibres, hollow synthetic fibres or solid synthetic fibres can for instance be manufactured. The fibres are preferably manufactured as solid fibres or bicomponent fibres. The synthetic fibres with fibrils according to the invention can be used in advantageous manner for manufacturing products comprising one or more synthetic fibres according to the invention. The fibres can suitably be used to manufacture for instance woven materials, knits or mats, or be processed in other appropriate manner. Such woven materials and mats can then be used to manufacture diverse products, such as for instance articles of clothing, or to manufacture filters. Such products comprising synthetic fibres according to the invention also form part of the present invention. The invention will be further illustrated with reference to the accompanying figures and examples, in which: Fig. 1 shows a synthetic fibre with fibrils according to the invention, wherein different forms of fibril are shown; Fig. 2 shows the contact points between different synthetic fibres according to the invention; Fig. 3 shows the use of the synthetic fibre in a woven material; and Fig. 4 shows a preferred embodiment of a nozzle according to the invention. Figure 1 shows schematically synthetic fibres according to the invention. Synthetic fibres 1 consist of a main stem 2 with fibrils 3 which protrude from the main stem. Fibrils 2 can have different shapes. By manufacturing the synthetic fibres while they are rotated synthetic fibres are for instance obtained with a main stem 2 and fibrils 3 which extend around the main stem. It becomes apparent from figure 2 that as a result of the fibrils many more contact points are present between the different synthetic fibres in materials manufactured with synthetic fibres according to the invention than if the materials were to be manufactured from synthetic fibres with a smooth surface. Figure 3 shows a woven material manufactured with the synthetic fibres 1 according to the invention. Owing to the fibrils the woven material has a "woollier" appearance than if the woven material were to consist of the smooth conventional synthetic fibre. Figure 4 shows schematically a preferred embodiment of a nozzle 5 according to the invention. Nozzle 5 herein comprises a passage for forming a main stem of synthetic fibre 6 which extends from an inlet 7 of nozzle 7 to an outlet 8, and a filling space 9 which is arranged concentrically round the passage for the main stem and which is connected to a number of moulding chambers 10 for forming of the fibrils. Moulding chambers 10 debouch in the passage for the forming of main stem 6 at an angle of about 45°. Filling space 9 is connected to a discharge channel 11 for excess polymer or polymer mixture. Different shapes and dimensions of the fibrils 3 can be obtained in simple manner with nozzle 5 by varying the dimensions of moulding chambers 10 and the angle at which moulding chambers 10 debouch in the passage for main stem 6. EXAMPLES EXAMPLE 1 Incorporated into a continuous fibre manufacturing process was a nozzle with a passage for the main stem with a diameter (D H ) of 0.5 mm. The moulding chambers debouching into the passage for the main stem had a narrowing of 0.1 mm. The injection conditions were as follows: Air injection: 5 bar. The speed of polymer material in the passage of smaller diameter was V=1500 m/min and the speed of the main flow was V=2000 m/min. Because the flow of polymer material of the main stem was higher there resulted fibrils. By placing the pressure intermittently on the passages of smaller diameter there occurred an interruption in the flow of the polymer material and fibrils resulted of varying length. The dimensions of the cooled nozzle according to the invention were in this example as follows: (D H ) = 0.5 mm, diameter of the outlet of the moulding chamber (D z ) = 0.1 mm, angle = 45°. The main stem was manufactured from polypropylene (PP) and the fibrils from polyester (PE) . The temperature in the nozzle was 150°C and cooling took place to 80°C. The pressure in the passage for the main stem was 150 bar, the pressure in the moulding chambers for the fibrils was 100 bar, intermittent. Table 1 shows the results. Table 1 EXAMPLE 2: Incorporated into a continuous manufacturing system for synthetic fibres (PP) was a nozzle according to the invention with a passage for the main stem with a diameter of 0.2 mm. The moulding chambers for the fibrils had a narrowing of 0.05 mm. The pressure difference between the main flow and the flow through the passages of smaller diameter was 50 bar. The pressure of the side flow was changed intermittently. Cooling with air took place immediately after outflow. The moulding chambers were situated on the nozzle at 2 mm distance from each other in a pattern such that they did not interfere with each other during injection. In order to determine the filtering capacity of the synthetic fibres according to the invention, filters manufactured from the synthetic fibres according to the invention were compared with filters of conventional smooth synthetic fibres. Air (5 g/1) saturated with microfibres was blown through the filters. Fibres of 20 mm length and with a cross-section of 0.2 mm 2 were used for the filters. The fibrils of the synthetic fibre according to the invention were 2 mm long. Tests were carried out with a lower weight per area of the synthetic fibre according to the invention. The results are shown in tables 2 and 3. Table 2: Conventional synthetic fibres Table 3: Synthetic fibre according to the invention It becomes apparent from tables 2 and 3 that the filters manufactured with the synthetic fibres according to the invention displayed a better filtering action (less residue in the filtered air) . EXAMPLE 3 A spun fibre of PES with gated fibrils of PP was mixed with cotton fibres. The PES fibres had a length of 30-60 mm and 10-15 denier. The injected fibrils had a length of 1-5 mm and 5-10 denier. The cotton fibres had a length of 10-15 mm. The mixing ratio was 30% fibre according to the invention and 70% cotton fibre. A mat was manufactured from the mixture by aerodynamic laying of fibres. By applying heat a connection was arranged between the melt fibres and the other fibres. The PP fibrils provide a good adhesion between the cotton fibres and the synthetic fibres. The specific properties of the mat were: weight: 1200 g/m 2 thickness: 24 mm density: 50 kg/m 3 Owing to their structure the synthetic fibres according to the invention provide a higher resilience and a lower specific weight. The new synthetic fibres are hereby very suitable for the acoustic industry, in all matrix structures, in particular in the automobile industry. EXAMPLE 4 Combinations of different synthetic fibres are used in the textile industry. When it is wished to combine the advantages of the one fibre with the advantages of the other fibre, it is necessary in conventional manner to produce these fibres separately and process them in combination to form a textile. Using the fibre according to the invention the advantages of a plurality of plastics can be combined in one fibre. A fibre is for instance injected from a polyamide stem and PES fibrils. (PA stem: 30-60 mm; 10-15 denier; PES fibrils: 1-5 mm; 2-8 denier) . After the spinning process the fibre is processed in a conventional production process to a usable textile fibre and used for instance as basis for a carpet in an automobile.

Claims: CLAIMS 1. Method for manufacturing synthetic fibres, comprising of forming a main stem from at least one polymer or polymer mixture and arranging on the main stem fibrils of at least one polymer or polymer mixture. 2. Method as claimed in claim 1, characterized in that the main stem of the synthetic fibre is manufactured from a first polymer or polymer mixture and that the fibrils are manufactured from a second polymer or polymer mixture . 3. Method as claimed in claim 1 or 2, characterized in that the polymer is chosen from the group consisting of polyamide, polyester or polypropylene, or a mixture thereof. 4. Nozzle for manufacturing a synthetic fibre with one or more fibrils, comprising a passage for forming a main stem of the synthetic fibre which extends from an inlet of the nozzle to an outlet, and at least one filling space which is connected to at least one moulding chamber for forming the fibrils, wherein the moulding chamber debouches in the passage for forming the main stem. 5. Nozzle as claimed in claim 4, characterized in that the filling space is a space arranged concentrically round the passage for the main stem. 6. Nozzle as claimed in claim 4 or 5, characterized in that the moulding chamber for forming of the fibrils debouches in the passage for the main stem at an angle of between 0 and 45°. 7. Nozzle as claimed in claim 5 or 6, characterized in that the filling space is connected to a discharge channel for excess polymer or polymer mixture. 8. Synthetic fibre comprising a main stem of at least one polymer or polymer mixture, and one or more fibrils of at least one polymer or polymer mixture protruding from the main stem. 9. Synthetic fibre as claimed in claim 8, characterized in that the main stem of the synthetic fibre is manufactured from a first polymer or polymer mixture and that the fibrils are manufactured from a second polymer or polymer mixture. 10. Synthetic fibre as claimed in either of the foregoing claims 8 or 9, characterized in that the polymer is chosen from the group consisting of polyamide, polyester or polypropylene, or a mixture thereof . 11. Synthetic fibre as claimed in any of the foregoing claims 8, 9 or 10, characterized in that the synthetic fibre is a solid fibre. 12. Synthetic fibre as claimed in any of the foregoing claims 8-11, characterized in that the synthetic fibre is a bicomponent fibre. 13. Product comprising one or more synthetic fibres as claimed in any of the foregoing claims 8-12. 14. Product as claimed in claim 13, characterized in that it is a filter. 15. Product as claimed in claim 13, characterized in that it is an article of clothing.

Inventors: JORIS GERARDUS MARTINUS ANTONI, JORIS, GERARDUS, MARTINUS, ANTONIUS
Applicants: ISOLATIE SYSTEMEN AKOESTIEK BV, JORIS GERARDUS MARTINUS ANTONI, ISOLATIE SYSTEMEN AKOESTIEK BVBA, JORIS, GERARDUS, MARTINUS, ANTONIUS
Application year: 2000
Main classification: D01D5
IPC codes: D01D5