EP1392897B1 - Method for producing fine monofilaments consisting of polypropylene, fine monofilaments consisting of polypropylene and the use thereof - Google Patents

Abstract

In a process for producing fine monofilaments having improved abrasion resistance from a polypropylene having a melt flow index (MFI)<SUB>230° C./2.16 kg </SUB>of 2-16 g/10 min at a linear density of 5-20 dtex (0.027 mm-0.053 mm), a compound consisting of 80 to 99.9% by weight of chips and 20 to 0.1% by weight of an additive is added to the extruder, the melt is spun at a speed of at least 1200 m/min, the fibre is cooled in an air bath at room temperature, supplementarily stretched at a temperature of 110-150° C. to a linear density of 5-20 dtex and wound up. The monofilaments comprising a polypropylene having a melt flow index (MFI)<SUB>230° C./2.16 kg </SUB>of 2-16 g/10 min, having improved abrasion resistance, and a linear density of 5-20 dtex (0.027 mm-0.053 mm) and an abrasion resistance score <=2. The monofilaments have a tenacity of at least 48 cN/tex and an elongation at break of less than 45% for a mechanical constant (constante méchanique) of at least 295 cN/tex and a specific work to break value of more than 61.5 cN.cm/dtex. The fine monofilaments according to the invention are useful for producing woven screen fabrics for filtration and screen printing without abrasion deposits.

Description

The invention relates to a process for the production of fine monofilaments with improved abrasion resistance from polypropylene with a melt flow index (MFI) 230 ° C / 2.16kg of 2-16g / 10min, a monofilament of polypropylene with a melt flow index (MFI) 230 ° C / 2.16 kg of 2-16 g / 10 min with improved abrasion resistance and a titre of 5-20 dtex (0.027 mm-0.053 mm), as well as its use.

Textile fabrics made of polypropylene are gaining increasing interest in the automotive industry, mainly because of their compared to other thermoplastics relatively lighter weight and improved resistance to climatic influences and mechanical stress. In this case, particularly fine monofilaments are required, which allow a further weight reduction. Fine monofilaments are to be understood as meaning smaller than 30 dtex, in particular smaller than 25 dtex.

Monofilaments of pure polypropylene, however, have the disadvantage of a strong dust formation as a result of its low abrasion resistance in the weaving process. The problem of abrasion is also known in other thermoplastics. Thus, EP-A2-0 784 107 calls melt-spun monofilaments of polyamide, polyester and polypropylene. Thereafter, abrasion resistant monofilaments are obtained with 70-99% by weight of filament-forming polymer and 1-30% by weight of a maleic anhydride-modified polyethylene / polypropylene rubber and other additives. However, the examples are limited to polyamide 6 and polyethylene terephthalate and a copolyamide of PA66 and PA6 as a filament-forming polymer. Spinning speeds are not specified. The relatively thick monofilaments are according to the examples, especially for paper machine screens and lawn mower wires suitable. No details are given for the preparation of relatively fine polypropylene monofilaments.

From EP-A-1059370 a process for the production of polypropylene multifilaments for textile purposes is known. The starting material is a metallocene-catalyzed isotactic polypropylene having a melt flow index of less than 25 g per 10 minutes to achieve the desired shrinkage properties. For the production of filaments, which are characterized by a deep shrinkage, it is preferable to use polypropylene granules having a high MFI value. About the yarns produced are only general information. Monofilaments are not described.

Also EP-A-0028844 describes a textile multifilament polypropylene filament yarn. Starting polymer is a polypropylene having a melt flow index between about 20 and 60. Under the specified spinning and stretching conditions as well as in the further processing, the problem of abrasion, which occurs in the processing of fine monofilaments, apparently not found.

The object of the invention is to provide an economical process for the production of fine, abrasion-resistant polypropylene monofilaments. Another object of the invention is the production of fine monofilaments of polypropylene with improved resistance to abrasion during weaving.

Yet another object is to provide the use of a fine monofilament having good abrasion resistance for making engineering fabrics.

The object is achieved according to the invention in that a compound consisting of 80 to 99.9% by weight of granules and 20 to 0.1% by weight of an additive is added to the extruder, the melt being spun at a rate of at least 1200 m / min, in the Air bath cooled at room temperature, at a temperature of 110 to 150 ° C to a titre of 5-20 dtex (0.027 mm-0.053 mm) nachverstreckt and wound. It is essential here that the additive is well dispersed in the polypropylene and no difference can be detected in the resulting monofilament.

For the first time, it has been possible to produce fine polypropylene monofilaments with a spinning speed of 1200 m / min. It has proven to be advantageous to use as additives modified polyolefins and aliphatic diesters.

As particularly advantageous additives are modified polyolefins in an amount of 4.5 to 15 wt .-%, in particular 6 to 13 wt .-%, preferably 8 to 12 wt .-% polypropylene / polyethylene having a melting point> 140 ° C to use. A melting point of less than 140 ° C has the disadvantage of costly dosing. At temperatures below 140 ° C sticking of the granules occur in the extruder. Use of less than 4.5% by weight and more than 15% by weight of polypropylene / polyethylene achieves unsatisfactory abrasion resistance of the monofilament. In this variant, surprisingly no further additives are required to achieve excellent abrasion resistance.

In a further variant, it is expedient to use as an additive 3-10% by weight, in particular 3 to 7% by weight, preferably 3 to 6% by weight, of an impact modifier. Suitable impact modifiers which show no softening up to 100 ° C. and are composed of linear styrene-ethylene / butylene-styrene block copolymers or linear styrene-ethylene / butylene-styrene block copolymer / styrene-ethylene / butylene-linear alloys. Biblock are constructed.

In a further variant, it is expedient to use as additive 0.1-0.2 wt .-% of a plasticizer. As a plasticizer, di-iso-nonyl adipate is most suitable.

In a further variant, it is expedient to use as an additive 0.05-1.0% by weight, in particular 0.3 to 1.0% by weight, of a lubricant. Metalloids of carboxylic acids, linear or branched hydrocarbons, fluoroelastomers, polydimethylsiloxanes are particularly suitable as lubricants.

In a further variant, it is expedient to use fillers as additive. As fillers, 0.01-0.1% by weight aerosils and 0.1-1.0% by weight calcium carbonate have proven to be particularly suitable.

In a further variant, the additive consists of a compound of a combination of 2-10% by weight of an impact modifier, 0.1-0.2% by weight Plasticizers, fillers 0.01-0.1 wt .-% Aerosil or 0.1-1.0 wt .-% calcium carbonate, 0.05-1.0 wt .-% of lubricants and 0.1-0.5 wt .-% of heat stabilizers. Suitable heat stabilizers are sterically hindered phenols, phosphites and phosphonites.

For the novel monofilaments defined in claim 9, the main polymer is a polypropylene having a melt flow index (MFI) of 230 ° C / 2.16kg of 2-16g / 10 min. and a titre of 5-20 dtex (0.027 mm-0.053 mm). A melt flow index of less than 2 g / 10 min has the disadvantage that too high melt spinning temperatures are required, which leads to the destruction of the polymer. A melt flow index of more than 16 g / 10 minutes has the disadvantage that the resulting abrasion resistance becomes insufficient. An abrasion resistance with a grade ≤ 2 results in a monofilament, which can be easily interwoven into a textile fabric and gives a surprising cleanliness.

The monofilament according to the invention has a strength of at least 47 cN / tex with a maximum breaking elongation of less than 45%.

The monofilament according to the invention has a mechanical constant of at least 285 cN / tex.

The invention will be described by examples.

example 1 polymer

The thread-forming monofilament used in all experiments was a polypropylene having a melt flow index (MFI) of 230 ° C. 12.16 kg of 12.0 g / 10 min. Each 5 kg of polypropylene granules are mixed using tinplate cans and a tumble mixer. The mixing was carried out according to the additive according to three different methods. The individual methods are explained under the examples. The granulate / additive mixture is added directly to the extruder and melted.

spinning conditions

extruder

Diameter 38 mm:
Maximum p = 100 bar
Throughput: 1-10 kg / h
6 heated zones

Spin Block:

Diphylbeheizt; 1 spinning station

Titerpumpe:

3-27 rpm

Spinnerets:

Outside diameter / inside = 85/70 mm

blowing shaft:

450-1100 m ³ / h; I = 1.3 m

Extruder temperatures for zones 1 to 5: 180/230/250/250/265/275 ° C.
Block + nozzles: 275/275 ° C
Throughput: 1.64 kg / h
Blowing air: 700 m ³ / h
Melting temperature: = 280 ° C
Spin-off speed: 1200 m / min

stretching conditions

The stretching takes place using a laboratory stretching machine, equipped with two drafting units, each of which is equipped with a godet (Ǿ = 10 cm) and a separating roller.

• Fadenbremse
• Streckwerk V1, welches mit einer zusätzlichen Förder- oder Gummiwalze ausgerüstet ist.- Ohne Streckstifte.
• Beheizbares Bügeleisen von 20 cm Länge im Abstand von 20 cm zum Streckwerk
• Streckwerk V2
• Traveller-Ringspindel
  Das Strecken der Varianten erfolgt bei einem Streckverhältniss 1: 3.6 und einer Bügeleisentemperatur (20 cm) von 130°C. Die Abzugsgeschwindigkeit des Streckwerks V2 beträgt 514 m/min.

The monofilaments go through the following organs during the stretching process:

• thread brake
• Drawframe V1, which is equipped with an additional conveyor or rubber roller.- Without draw pins.
• Heated iron of 20 cm length at a distance of 20 cm to the drafting system
• Drafting system V2
• Traveler-ring spindle
  The stretching of the variants takes place at a draw ratio of 1: 3.6 and an ironing temperature (20 cm) of 130 ° C. The take-off speed of the drafting system V2 is 514 m / min.

Example 2 (Experiments 2-4)

In the case of the modified polyolefins, the granulate mixture consisting of polypropylene and modified polyolefin, PP / PE melting point> 140 ° C., is mixed for one hour.

Example 3 (Experiments 5-7)

In the case of the modified polyolefins, the granulate mixture consisting of polypropylene and impact modifier is mixed for one hour. The addition of an antistatic agent, such as 0.1% Atmer 110 (trademark of Uniqema) is advantageous in these mixtures.

Example 4 (Experiments 8 and 9)

The plasticizer is added to the polypropylene granules followed by mixing for two hours.

Example 5 (experiments 10-12)

For the powdery additives such as fillers, lubricants, heat stabilizers, etc., the granules are first rolled for half an hour with an adhesion promoter such as Basilon M100 (trademark of Bayer AG), then the remaining additives are added and mixed for a further 1.5 hours. The incorporation of calcium carbonate in polypropylene analogous description above includes this series of experiments.

Example 6 (Experiments 13-16)

In this example, a lubricant in different amounts is added to the polymer.
Same preparation as example 5.

Example 7 (Experiments 17-19)

In the case of the additives in the form of a combination of different compounds, test 17 contains two different lubricants (0.2 and 0.05%) and Aerosil 0.05%. Experiments 18 + 19 are based on three additives 0.35% heat stabilizer, 0.3% calcium carbonate and 0.15% lubricant 4 0.5% heat stabilizer, 0.2% lubricant 4 and 0.01% aerosol

Same preparation as example 5.

The results are summarized in Table 1 Table 1 test number ADDITIVE ABTERNOTE Titre [dtex] Strength [cN / tex] Elongation at break [%] Mechanical constant [cN / tex] Special tear work [cN.cm/dtex] 1 0 4 9.9 51.4 32.6 293.47 61.4 2 5% 1.8 10.4 53.5 31.7 301.22 62.69 3 10% 1.0 10.4 54.1 30.3 297.80 59.57 4 15% 2.0 10.8 53.3 30.6 294.84 59.20 5 3% 2.0 10.8 47.7 41.1 305.80 76.52 6 04.05% 0.8 10.4 48.9 42.9 320.29 82.50 7 6.0% 0.8 10.4 48.4 41.1 308.78 77.07 8th ≤ 0.10% 1.66 10.8 48.8 34.5 286.63 62.92 9 00:15% 10 0.4% 2.5 10.4 49.5 29.3 267.94 51.46 11 01.02% 0.83 11.2 47.2 43.4 310.95 81.67 12 2.0% 13 0.2% 3.66 10.1 50.5 31.8 284.78 58.53 14 0.5% 1:33 10.4 51.2 34.9 302.47 67.17 15 0.8% 0.83 10.4 51.4 32.1 291.22 60.81 16 1.0% 1.16 10.4 51.9 30.3 285.69 67.36 17 0.2 / 0.05 / 0.05% 0.83 10.4 51.6 34.1 301.32 65.65 18 0.35 / 0.3 / 0.15% 0.83 10.8 49.3 37.1 300.29 69.53 19 0.50 / 0.2 / 0.01% 1.16 10.8 51.5 40.7 328.55 78.97 Tests 2-4 Polypropylene MFI 12.0 g / min with PP / PE, mp> 140 ° C as additive;
Run 5-7 polypropylene MFI 12.0 g / min with an impact modifier;
Run 8-9 polypropylene MFI 12.0 g / min with a plasticizer additive;
Run 10-12 polypropylene MFI 12.0 g / min with a filler additive;
Runs 13-16 polypropylene MFI 12.0 g / min with a lubricant as an additive;
Run 17-19 polypropylene MFI 12.0 g / min with a compound as an additive

The results are shown graphically for further explanation.

Show it:

• 1 shows the abrasion behavior as a function of the addition of an additive according to Example 2.
• 2 shows the abrasion behavior as a function of the addition of an additive according to Example 3.
• 3 shows the abrasion behavior as a function of the addition of an additive according to Example 6.

In Fig. 1, the curve when adding a modified polypropylene / polyethylene with a melting point> 140 ° C according to. Example 2 shown. Without the addition of an additive, the pure polypropylene shows a rating of 4 in the abrasion test, which represents unsatisfactory abrasion in the fabric. It is surprising that, with increasing addition, the abrasion can be initially improved up to an addition of 10% by weight and worsen again at higher additions.

FIG. 2 shows the curve when adding an impact modifier. With increasing amount of additive, the abrasion initially decreases and reaches a minimum at 5% by weight. Another raise brings no advantage.

In Fig. 3 the curve is shown with the addition of different lubricants. Here, small amounts added initially bring a marked improvement in the abrasion behavior. An increase brings no further improvement in the abrasion behavior.

measurement methods

• Melt flow index according to ASTM D1238
• Abrasion Test - Test Method (ABTER)

• das Abriebverhalten wird an allen Monofilen während einer Laufzeit von 16 Stunden geprüft
• die Webblätter werden dem Testgerät entnommen und fotografiert
• die visuelle Beurteilung der Ablagerungen an den Webblättern erfolgt durch drei Personen, wobei die Einstufung durch Vergeben von Noten erfolgt (0-1 = kein Abrieb, 5 = viel Abrieb)

• Bestimmung des Titers nach SN 197 012 und SN 197 015 zusätzlich DIN 53 830
• Zugversuche nach DIN 53 815, DIN 53 834 und zusätzlich BISFA
• Die Berechnung der mechanischen Konstante, CM, erfolgt nach der Formel: $$\mathrm{C}\mathrm{M}=\sqrt{\mathrm{D}}\cdot \mathrm{F}\left[\mathrm{c}\mathrm{N}/\mathrm{t}\mathrm{e}\mathrm{x}\right]$$
  
  wobei D, Dehnung in [%] und F, Festigkeit in [cN/tex] bedeuten.

The abrasion test is a simple simulation of the weaving process on a test device without weft insertion. The monofilaments are guided at a constant speed through the most important elements of a loom such as reed and strands, which also perform the corresponding movements. The thread speed is 9 m / h, the reed performs 525 double strokes per minute.
The evaluation of the Abriebsverhaltens with the ABTER tester is made as follows.

• The abrasion behavior is tested on all monofilaments during a running time of 16 hours
• The reeds are taken from the test device and photographed
• the visual assessment of the deposits on the reeds is carried out by three persons, the grading being done by assigning grades (0-1 = no abrasion, 5 = a lot of abrasion)

• Determination of the titer according to SN 197 012 and SN 197 015 additionally DIN 53 830
• Tensile tests according to DIN 53 815, DIN 53 834 and additionally BISFA
• The calculation of the mechanical constant, CM, follows the formula: $$\mathrm{C}\mathrm{M}=\sqrt{\mathrm{D}}\cdot \mathrm{F}\left[\mathrm{c}\mathrm{N}/\mathrm{t}\mathrm{e}\mathrm{x}\right]$$
  
  where D, strain in [%] and F, mean strength in [cN / tex].

The novel fine monofilaments are suitable for abrasion-free production of screen fabrics for filtration and screen printing.

Claims (13)

1. Process for producing fine monofilaments having abrasion resistance from a polypropylene having a melt flow index (MFI) 230°c/z.16 kg of 2-16 g/ 10 min, characterized in that a compound consisting of 80-99.9% by weight of polypropylene chips and 20 to 0.1% by weight of an additive is added to the extruder, the melt is spun at a speed of at least 1200 m/min, the fibre is cooled in an air bath at room temperature, supplementarily stretched at a temperature of 110 to 150°C to a linear density of 5-20 dtex (0.027 mm-0.053 mm) and wound up.
2. Process according to Claim 1, characterized in that the additive used is selected from modified polyolefins and aliphatic diesters.
3. Process according to Claim 1, characterized in that the additive used is 4.5 to 15% by weight of a polyolefin from polypropylene/polyethylene having a melting point >140°C.
4. Process according to Claim 1, characterized in that the additive used is 3-10% by weight of an impact modifier.
5. Process according to Claim 1, characterized in that the additive used is 0.1-0.2% by weight of a plasticizer.
6. Process according to Claim 1, characterized in that the additive used is 0.05 to 1.0% by weight of a lubricant.
7. Process according tc Claim 1, characterized in that the additive used is 0.01-1.0% by weight of fillers.
8. Process according to Claim 1, characterized in that the additive used is a compounded combination of impact modifier, plasticizer, fillers, lubricants and heat stabilizers.
9. Monofilaments comprising a polypropylene having a melt flow index (MFI) 230°C/2.16 kg of 2-16 g/10 min and having abrasion resistance obtainable by the process of claim 1, having a tenacity of at least 47 cN/tex and an elongation at break of less than 45%, having a mechanical constant (constante méchanique) of at least 285 cN/tex, and having a linear density of 5-20 dtex (0.027 mm-0.053 mm).
10. Monofilaments according to Claim 9, characterized by a specific work to break value of more than 61.5 cN·cm/dtex.
11. Use of the monofilaments according to Claim 9 or 10 for producing industrial fabrics.
12. Use of the fabrics according to Claim 11 as filtration fabrics.
13. Use of the fabrics according to Claim 11 in screen printing.

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