EP1004691A1 - Core-sheath bicomponent fibres for papermaking clothing - Google Patents

Abstract

Two-component core-shell fibres in which the shell consists of 45-98 wt% polyamide (1) with a melting point of more than 280 degrees C, 2-20 wt% layer silicate and 0-35 wt% of a second polyamide (2), while the core consists essentially of polyamide 2.

Description

TECHNICAL AREA

The present invention relates to the field of synthetic fibers as they are usually for the production of paper machine felts, especially of Paper machine felts for use in the press area of paper machines be used. It concerns a core-sheath bicomponent fiber which too essential parts made of polyamide. It also affects use of such a fiber for the production of paper machine felts.

STATE OF THE ART

Press felts serve to support the paper mass in paper machines and absorb water from the paper pulp during the pressing process. This usually happens in the paper making process immediately after Headbox and the Fourdrinier section, and before the paper web in the dryer section is completely dried.

To increase the drainage capacity in the pressing process, the last Years, the temperatures in the press area of paper machines continue to rise increased (B. Wahlstrom, "Pressing-the state of the art and future possibilities", Paper technology, February 1991, pp. 18-27). New developments such as "hot pressing" or "Impulse Pressing" (see e.g. D. Orloff et al. TAPPI Journal Vol. 81 (07/1998), p. 113-116 and H. Larsson et al. TAPPI Journal Vol. 81 (07/1998), pp. 117 - 122) sometimes work at very high temperatures. The high temperatures (at On the one hand, impulse pressing (sometimes above 200 ° C) leads to an advantageous one Lowering the viscosity of the water, but on the other hand, claim the in the Press felts processed fibers enormously. So are due to the high temperatures in particular synthetic fibers are soft at least in the jacket region, which leads to a Increase in compaction and abrasion of the felts. At increasing compaction, the fibers stick together, the spaces in the felt become smaller and with it the ability of the felt to decrease water pick up and remove the paper.

For long felt runtimes and therefore the shortest possible downtimes of the machines Having is a very important criterion for the applicability of fibers for Press felts have high abrasion resistance and low compaction. Out For this reason, press felts are made almost exclusively of polyamide 6 (PA 6) or PA 66 fibers and monofilaments, but felts made from PA 11 are also used in the literature Fibers (EP 0 372 769), and PA 12 fibers (EP 0 287 297) etc. are described.

PEEK (polyether ether ketone) fibers were also used, for example (EP 0 473 430) or PTFE (polytetrafluoroethylene) fibers (WO 92/10607) for use in Paper machine felts tested. They prove to be true Temperature resistance as suitable due to their low Abrasion resistance, however, does not allow acceptable felt runtimes.

The use of fibers from partially aromatic polyamides, as well as a structure of the Fibers arranged as bicomponent fibers from two side by side Components have been proposed (EP 529 506), but they are also used such fibers have not yet achieved sufficient abrasion resistance.

Compacting should be prevented by coating fibers with it Layered silicates, or by producing fibers containing layered silicates and Monofilaments (WO 97/27356; EP 0 070 709). Incorporation of the layered silicates into the However, fiber polymer has the disadvantage that the strength of the fibers is strong decreases.

EP 0 741 204 describes the use of core-jacket bicomponent adhesive fibers described for press felts, which are primarily designed to the surface quality, the running properties of the felt, the recovery and to improve drainage. This happens through sticking, which by Melting the jacket component are generated.

PRESENTATION OF THE INVENTION

The invention is therefore based on the object of providing a fiber which, processed into a paper machine felt, for example, is sufficient Has abrasion resistance and at the same time high temperatures, in particular under the conditions that occur with Impulse Pressing, withstands without to be compacted and glued.

This object is achieved with a fiber of the type mentioned by the Fiber is formed as a core-jacket bicomponent fiber, which has a core and has a jacket at least partially enclosing the core, and in that the sheath consists of 45-98% by weight of a first polyamide, which has a melting point of more than 280 ° C, and 2 - 20% by weight of one Contains layered silicates. The core also consists of a second polyamide. In addition, the coat also contains up to 35% by weight of this second Polyamides. The essence of the invention is therefore the fiber as a core-jacket bicomponent fiber build up, and by a layered silicate containing and refractory mantle both to prevent the compaction as well as a Achieve high abrasion resistance by storing the silicates caused reduction in the strength of the fiber but thereby preventing a solid core is present. Because the core is made of a second polyamide and the sheath also contains up to 35% by weight of this second polyamide contains an intimate connection between the core material and the Jacket material ensured.

A preferred embodiment has the feature that at least the core or the jacket or both parts contains up to 1% by weight of heat stabilizers, and that especially these heat stabilizers hindered phenols, Phosphonic acid derivatives, phosphites or combinations of these stabilizers are. This is another effective measure to increase heat stability and thus to prevent the two-component fiber from compacting.

In addition, the invention claims the use of such fiber according to the invention for producing a paper machine felt, especially a needled paper machine felt, which is still preferred for use in the press area, especially for impulse pressing or is designed for hot pressing.

Other embodiments of the core-sheath bicomponent fiber and the Use of the same results from the dependent claims.

WAYS OF CARRYING OUT THE INVENTION

In the description of the production of a fiber according to the invention from two as The core and sheath-formed components should initially be the composition of the core, then that of the cladding are discussed.

The core is preferably made of PA 6 or PA 66 with a relative solution viscosity from 2.4 - 5.0 (1 g polymer per 100 ml 96% sulfuric acid at 25 ° C) or from Mixtures of appropriate PA 6 and PA 66 qualities in a ratio of 1:99 to 99: 1 manufactured. Polyamides of the types PA 11, PA 12, PA 69, PA 610, PA 612 or PA 1212 with a relative solution viscosity of 1.6 - 2.8 (0.5 g polymer per 100 ml m-cresol at 25 ° C) are used. Furthermore the core should preferably contain 0-1% by weight of heat stabilizers, e.g. based sterically hindered phenols, phosphonic acid derivatives or phosphites or Combinations of these stabilizers. The core thus provides the necessary strength the fibers, for example when they are processed into felts.

The jacket should be made of a polyamide with a melting point of at least 280 ° C, and it should also contain 2-20% by weight of layered silicates (e.g. MICROMICA® MK 100 from CO-OP Chemical CO., LTD. Japan) and 0-35 % By weight of the polyamide type from which the core is constructed. Suitable Polyamides with a melting point of at least 280 ° C are e.g. PA 46, PA 46 / 4T, PA 66 / 6T, PA6T / 6I, PA 9T, PA 10T, PA 12T and 2-methyl-1,5 pentanediamine T / 61 (MPMD T / 61), these polyamides up to 20% by weight of other monomers such as. Caprolactam or Laurinlactam can contain. The coat contains each also 0-1% by weight of heat stabilizers, e.g. sterically based hindered phenols, phosphonic acid derivatives or phosphites or combinations of these stabilizers. The layered silicates can either be compounded can be incorporated into the polymer by means of a twin-screw extruder or but in the polymerization of one of the PA components right from the start Polymerization can be added, which enables better distribution. For Can improve the adhesion between polyamide and layered silicate particles of course additional adhesion promoters such as Amino silanes are used.

The core can be surrounded concentrically or non-concentrically by the jacket. At A non-concentric core-shell distribution can be achieved by suitable spinning and Stretching conditions a helical crimp can be generated.

The mass ratio of core to cladding is between 30:70 and 70:30, but other component ratios are also possible.

The titer range, i.e. the fineness of the bicomponent fibers, expressed as length-related mass, extends from 6.7 to 100 dtex (1dtex = 0.1 tex = 0.1 g / km), but in principle there are also fibers outside this range producible.

In contrast to the core-sheath bicomponent adhesive fiber described above (EP 0 741 204) brings about the core-jacket bicomponent fiber according to the invention Prevention of sticking or compacting of the nonwoven fabric at high Temperatures. This is very important since the core-jacket bicomponent fibers according to the invention not only used in small amounts in the felt, but represent the main fiber component at least in the top layer.

The production of several comparative examples as well as the exemplary embodiments will proposed in detail as follows:

Example 1: (Comparative example) A fleece with a basis weight of 200 g / m ^{2 was} produced from 17 dtex PA 6 fibers of the type TM 4000 from EMS Chemie AG. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

Example 2: (Comparative example) 17 dtex fibers were produced as follows: 89.5% by weight PA 6 with relative viscosity 3.4 (1 g polymer per 100 ml 96% Sulfuric acid at 25 ° C), 10% by weight layered silicate type MICROMICA® MK 100, 0.5 % By weight heat stabilizer Irganox® 1098 (Clariant, formerly Ciba-Geigy) was also used a twin screw extruder compounded at 280 ° C after all components had been pre-dried. The compounded material was dried and opened spun into fibers in a spinning system, stretched, crimped and cut.

Machine settings: melt temperature at the extruder head: 300 ° C;
Temperature spinning beam and nozzle pack: 300 ° C Spinneret: 279 holes Hole diameter: 0.6 mm Throughput: 1066 g / min Spinning speed: 1000 m / min Preparation pad (phosphoric acid ester) 0.3% Draw ratio 2.4 Temperature stretch godets air jet texturing 170 ° C Dryer temperature 170 ° C Cutting length 80 mm

A fleece with a basis weight of 200 g / m ^{2 was} produced from the resulting fibers. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

Example 3: (Comparative example) 17 dtex fibers were produced as follows: 89.5% by weight of PA 6T / 66 type Arlen® C2300 (PA 66 / 6T, from MITSUI, melting point 290-295 ° C), 10% by weight layered silicate type MICROMICA® MK 100 and 0.5% by weight Heat stabilizers Irganox® 1098 were used with a twin-screw extruder at 315 ° C compounded after all components had been pre-dried. The Compounded material was dried and added to the spinning system mentioned Fibers spun.

Machine settings: melt temperature at the extruder head: 315 ° C;
Temperature spinning beam and nozzle pack: 315 ° C. Spinneret: 279 holes Hole diameter: 0.6 mm Throughput: 1066 g / min Spinning speed: 1000 m / min Preparation pad (phosphoric acid ester) 0.3% Draw ratio 2.4 Temperature stretch godets air jet texturing 190 ° C Dryer temperature 190 ° C Cutting length 80 mm

A fleece with a basis weight of 200 g / m ^{2 was} produced from the resulting fibers. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

Example 4: (Comparative example) 17 dtex core-sheath bicomponent fibers with one Core-shell ratio 50/50 was produced as follows: Core component: PA 6 with relative viscosity 4.0 (1 g polymer per 100 ml 96% Sulfuric acid at 25 ° C) and 0.5% by weight heat stabilizer Irganox® 1098. Jacket component: 99.5% by weight PA 6T / 66 (Arlen® C 2300), 0.5% by weight Heat stabilizer Irganox® 1098, the heat stabilizer in the form of a 5% Masterbatch in PA 6T / 66 (Arlen® C 2300) was added. Both components were dried and on the above-mentioned system with a bicomponent spinneret spun into core-sheath fibers.

Machine settings: melt temperature of the core component at the extruder head: 300 ° C; Melt temperature of the jacket component at the extruder head: 315 ° C; Temperature spinning beam and nozzle pack: 315 ° C. Spinneret: 210 holes Hole diameter: 0.7 mm Throughput per component: 401 g / min Spinning speed: 1000 m / min Preparation pad (phosphoric acid ester) 0.3% Draw ratio 2.4 Temperature stretch godets air jet texturing 180 ° C Dryer temperature 190 ° C Cutting length 80 mm

A fleece with a basis weight of 200 g / m ^{2 was} produced from the resulting fibers. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

Example 5: 17 dtex core-sheath bicomponent fibers with a core-sheath ratio 50/50 were manufactured as follows: Core component: PA 6 with relative viscosity 4.0 (1 g polymer per 100 ml 96% sulfuric acid at 25 ° C) and 0.5 wt.% Irganox® 1098 heat stabilizer. Jacket component: 25 wt.% PA 6 with relative viscosity 2.8 (1 g polymer per 100 ml 96% sulfuric acid at 25 ° C), 10% by weight layered silicate type MICROMICA® MK 100, 64.5% by weight PA6T / 66 (Arlen® C 2300) and 0.5% by weight heat stabilizer Irganox® 1098 were mixed with a Twin-shaft extruder at 315 ° C compounded after all components had been pre-dried. Both components were dried and on the Bicomponent spinning system spun into core-jacket fibers.

Machine settings: melt temperature of the core component at the extruder head: 300 ° C; Melt temperature of the jacket component at the extruder head: 315 ° C; Temperature spinning beam and nozzle pack: 315 ° C. Spinneret: 210 holes Hole diameter: 0.7 mm Throughput per component: 401 g / min. Spinning speed: 1000 m / min Preparation pad 0.3% (Phosphoric acid ester) Draw ratio 2.4 Temperature stretch godets air jet texturing 180 ° C Dryer temperature 190 ° C Cutting length 80 mm

A fleece with a basis weight of 200 g / m ^{2 was} produced from the resulting fibers. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

Example 6: 17 dtex core-sheath bicomponent fibers with a core-sheath ratio 50/50 were manufactured as follows: Core component: PA 66 with relative viscosity 3.4 (1 g polymer per 100 ml 96% sulfuric acid at 25 ° C) and 0.5% by weight heat stabilizer Irganox® 1098. Sheath component: 25% by weight PA 66 with relative viscosity 2.8 (1 g polymer per 100 ml 96% sulfuric acid 25 ° C), 10% by weight layered silicate type MICROMICA® MK 100, 64.5% by weight PA 6T / 66 (Arlen® C 2300) and 0.5% by weight heat stabilizer Irganox® 1098 were mixed with a Twin-shaft extruder at 315 ° C compounded after all components had been pre-dried. Both components were dried and on the Bicomponent spinning system with the same settings as in example 4 Core-sheath fibers spun.

A fleece with a basis weight of 200 g / m ^{2 was} produced from the resulting fibers. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

Example 7: 17 dtex core-sheath bicomponent fibers with a core-sheath ratio 50/50 were manufactured as follows: Core component: PA 6 with relative viscosity 4.0 (1 g polymer per 100 ml 96% sulfuric acid at 25 ° C) and 0.5% by weight heat stabilizer Irganox® 1098. Sheath component: 10% by weight Layered silicate type MICROMICA® MK 100, 89.5% by weight PA 6T / 66 (Arlen® C 2300) and 0.5 wt.% Irganox® 1098 heat stabilizer was used with a twin-screw extruder 315 ° C compounded after all components had been pre-dried. Both components were dried and on the bicomponent spinning system spun the same settings as in Example 4 to core-sheath fibers.

A fleece with a basis weight of 200 g / m ^{2 was} produced from the resulting fibers. Three layers of this fleece were needled onto the paper side and two layers onto the machine side of a PA 6 monofilament fabric. This test felt was then fixed at 165 ° C for 10 minutes.

The above example fibers processed into felts were the following tests subjected, the results are summarized in Table 1.

1. Abrasion test:

Part of the felt was treated on a felt test press (FTP) (according to DE 44 34 898 C2, page 5 lines 27 to 56 and figures). The water temperature was up 50 ° C set.

The fiber loss is given to assess the abrasion. The lower the Fiber loss is the better the abrasion resistance.

2. Temperature resistance (resistance to compacting at high Temperatures):

Another part of the felt was initially in demineralized water for 24 hours stored at room temperature and then treated as follows:

The damp felt is treated with a calender in a tensioning device (lower Roller T = 205 ° C, upper roller cold, line pressure: 70 kN / m). The felt runs through a felt length of 2 m and a speed of 30 m / min the calender every 4 Seconds. With an assumed nip width of 20 mm, the dwell time is approx. 40 milliseconds in the nip. The test duration is 4 hours, i.e. 3600 cycles.

The quality of the felt is assessed by the percentage air permeability (L) of the felt (L ₁ ) after this treatment based on the air permeability of the felt (L ₀ ) before the treatment. The greater this value, the better the felt or the corresponding fibers are suitable. At a calender temperature of 50 ° C, this value for Comparative Example 1 is L = 71%. variant 1 2nd 3rd 4th 5 6 7 Fiber loss [g / m ² ] 16 93 163 43 30th 38 45 Air permeability L [%] 3rd 35 65 45 63 67 65

During comparison variant 1 due to total compacting at high Temperature is unusable, comparative variant 3 results in a very poor result Abrasion resistance. In comparison variant 2, the compacting significantly reduced, but the level is not acceptable and the Abrasion resistance decreases significantly. In comparison variant 4, too Compacting still too strong.

In Examples 5 to 7 according to the invention, the abrasion resistance decreases Although also from, the results are still in a range that in the Paper industry state of the art and accepted.

Compacting at high temperatures is significantly less than that of the Comparative variants 1 and 2.

Claims (10)

Core-jacket bicomponent fiber, which has a core and a den Core at least partially enclosing sheath, thereby characterized that the sheath to 45 - 98 wt.% From a first Polyamide exists, which has a melting point of more than 280 ° C has, and 2 - 20 wt.% Of a layered silicate that the Core essentially consists of a second polyamide and that the sheath also contains 0-35% by weight of this second polyamide. Core-jacket bicomponent fiber according to claim 1, characterized characterized in that the second polyamide made of PA 6 or PA 66 a relative solution viscosity of 2.4 - 5.0, measured in Sulfuric acid, with 1 g of polymer per 100 ml of 96% sulfuric acid at 25 ° C, or a mixture of appropriate PA 6 and PA 66 qualities. Core-jacket bicomponent fiber according to claim 1, characterized characterized in that the second polyamide made of PA 11, PA 12, PA 69, PA 610, PA 612 or PA 1212 with a relative solution viscosity of 1.6 - 2.8, measured in m-cresol, with 0.5 g polymer per 100 ml m-cresol is considered at 25 ° C, or a mixture of the above Fabrics. Core-jacket bicomponent fiber according to one of claims 1 to 3, characterized in that the first polyamide made of PA 46, PA 46 / 4T, PA 66 / 6T, PA6T / 6I, PA 9T, PA 10T, PA 12T or MPMDT / 6I, or a mixture of the substances mentioned, and that it is up to 20% by weight of other comonomers such as, for example, caprolactam or contains laurolactam. Core-sheath bicomponent fiber according to one of claims 1 to 4, characterized in that the core or the cladding or both Contains components up to 1% by weight of heat stabilizers. Core-jacket bicomponent fiber according to claim 5, characterized characterized that the heat stabilizers are sterically hindered Phenols, phosphonic acid derivatives, phosphites or combinations of these are stabilizers. Core-sheath bicomponent fiber according to one of claims 1 to 6, characterized in that the fiber has a length-related mass in the range from 5 to 200 dtex, particularly preferably in the range from 6.7 to 100 dtex. Core-jacket bicomponent fiber according to one of claims 1 to 7, characterized in that the mass ratio of core to Sheath is in a range from 7: 3 to 3: 7. Use of a core-sheath bicomponent fiber according to one of the Claims 1 to 8 for the production of a paper machine felt, especially a needled paper machine felt. Use of a core-sheath bicomponent fiber according to claim 9, characterized in that the paper machine felt on the Application in the press area, especially for impulse pressing or is designed for hot pressing.