JPH07189021A - Method for spinning for manufacturing polyolefin fiber with high heat weldability - Google Patents

Abstract

PURPOSE: To obtain the titled fibers suitable for producing nonwoven fabrics and excellent in thermobondability even by a short spinning apparatus by specifying a real or equivalent output hole diameter of a spinning die. CONSTITUTION: The real or equivalent output hole diameter of the spinning die is made to have over 0.5 mm, particularly 0.5 to 2 mm. The ratio of the output hole diameter to the fiber denier is made to be over 0.06 mm/dtex, preferably over 0.1 mm/dtex when producing fibers having over 4 dtex. This spinning method is useful for producing thermobonable polyolefin fibers having 0.2 to 10 dtex, particularly 0.5-3 dtex, fineness.

Description

Detailed Description of the Invention

The present invention relates to a spinning method for producing heat-weldable polyolefin fibers, especially polypropylene fibers, which is suitable for producing nonwoven fabrics. The non-woven fabric is generally 0.2 to
Requires very high flexibility and tear resistance, as is the case with diapers and sanitary covers made from 5 dtex low count fiber or thin films made from 3-10 dtex count fiber It is particularly suitable for the intended use. The basic requirement for non-woven polyolefin fibers is that the fibers must bond to each other by the combined effect of temperature and pressure in hot calendering. This property, called "heat weldability", is not always present, or at least not to the same extent, in polyolefin fibers. In fact, the heat weldability basically depends on the type of polyolefin to be spun, the additives it contains, the type of process and the spinning conditions used.

Published European patent application No. 391438 is suitable for spinning, organic phosphites and / or phosphites, HALS (Hindered Amine).
Light Stabilizers) and optionally a polyolefin composition characterized by the presence of a stabilizer selected from phenolic antioxidants. The patent application describes heat-weldable fibers obtained from the above stabilized polyolefin compositions by conventional spinning methods, in particular staple fiber manufacturing methods. In this case, the good heat weldability levels shown in the examples are due to the choice of stabilizer. In the above embodiment, 1.9 to 2.2 dtex
Fibers with a count of 4 are typical "long-spinning" devices (especially with a die with holes having a diameter of 0.4 mm).
Characterized by high fiber winding speeds).

The use of dies with small diameter (0.4 mm or less) holes to produce low count fibers is
Long-spinning equipment as described above, as well as "short-spinning" equipment, and spun-bonding, both used to make staple fibers.
It is common for machines to have high productivity. fact,
The smaller the hole diameter, the more holes in the die and the more fibers per unit time. For this reason, the use of dies with holes with diameters greater than 0.4 mm is
Limited to the production of high count fibers (higher than 5 dtex).

Surprisingly, the use of dies with holes with a diameter of more than 0.5 mm, both in the production of staple fibers and in the spun-bonding process, makes it possible to obtain fibers with a count of more than 4 dtex. However, it was found that the heat weldability of the fiber was significantly increased, provided that the ratio of hole diameter to count was sufficiently high.
Therefore, in the present invention, the count is preferably 0.2 to 10 dte.
x, more preferably 0.5 to 3 dtex of heat-weldable fiber, wherein the die used has a true or corresponding exit hole diameter of 0.5 mm or more, especially 0.5 to 2 mm. However, for fibers having a count of 4 dtex or more, the ratio of the exit hole diameter to the count is 0.06 mm / dte.
x or more, preferably 0.08 mm / dtex or more, more preferably 0.1 mm / dtex or more is provided.

As used herein, "exit hole diameter" means the diameter of the hole at the outer surface of the die, ie, the die surface from which the fibers exit. Inside the die thickness, the hole diameter may differ from the diameter at the exit. Furthermore, "equivalent exit hole diameter" applies when the hole is not circular, in which case, for the purposes of the present invention, consider the diameter of an ideal circle having an area equal to the area of the exit hole, It means this diameter. As mentioned above, the method of the present invention can be carried out using long-spinning and short-spinning equipment for making staple fibers, and spun-bonding equipment.

Long-spinning equipment usually comprises a first spinning zone in which the fibers are extruded and air cooled in a quench column. Subsequently, these fibers proceed to a finishing process during which they are drawn, pleated, bulked and chopped. In general, the finishing steps described above are carried out intermittently in special areas for spinning, where the fiber rovings are collected in a single roving of a total count of 100-200 kilotex. The roving is then fed to a device for drawing, crimping-bulking and cutting, which is operated continuously at a spinning speed of 100-200 m / min. In another type of long-spinning machine, the finishing process described above is carried out in succession to the spinning process. In this case, the fibers proceed directly from the collecting roller to the drawing roller, where they are drawn at a moderately slow rate (not to exceed 1.5). The fibers are then collected in a roving of a count of about 5 kilotex, then subjected to a crimping-bulking process and cut at a speed comparable to spinning.

In addition, the long-spinning apparatus has excellent controllability of process conditions as compared with the controllability of the short-spinning apparatus. General process conditions when using a long-spinning apparatus are: -hole flow rate> 0.2g / min,-fiber accumulation speed ≥ 500m / min,-space where the fiber cools after exiting the die and solidifies>
It is 0.50 m. The above conditions can be applied to the method of the present invention as long as the operation is performed by a long-spinning device and the die used is the above die. Preferably, it operates within the following time range. -Hole flow rate 0.15-1.0 g / min, preferably 0.2-
0.5 g / min-Fiber accumulation speed 500-3500 m / min, preferably 6
00 to 2000 m / min Further, the stretching ratio is preferably 1.1 to 4.0. For more details on long-spinning equipment, see Friedhelm Hauser “Plastics Extrusion Technolog.
See y ”, Hauser Publishers, 1988, chapter 17.

It has been found that the heat weldability of staple fibers improves as the rate of fiber accumulation decreases. Especially in the case of staple fibers, the method of the invention is particularly advantageous when using short-spinning devices, in particular with low fiber accumulation speeds (less than 500 m / min).
The above short-spinning device has a spinning speed of stretching,
Consistent with crimping and cutting speeds, continuous operation is possible, simple and small overall volume makes these devices more economical than long-spinning devices and suitable for small scale production. However, hitherto, the short-spinning apparatus has not been able to obtain staple fibers having good values for heat weldability (for example, according to the measuring method described in Examples, more than 2.5 N). Therefore, the method of the present invention is of particular importance when using a short-spinning device as it solves the problem of producing heat-weldable staple fibers even when working in a short-spinning device.

According to the present invention, the most suitable process conditions for using the short-spinning apparatus are as follows. Hole flow rate is 0.005-0.18 g / min, preferably 0.008-0.070 g / min, more preferably 0.01
It is 0 to 0.030 g / min. Fiber accumulation speed is 30-50
It is 0 m / min, preferably 40 to 250 m / min, more preferably 50 to 100 m / min. Stretching ratio is 1.10-3.5
It is 0, preferably 1.20 to 2.50. Furthermore, the space for cooling and solidifying the fibers at the exit of the die is preferably more than 2 mm, more preferably more than 10 mm and especially 10-350 mm. The cooling is generally performed by jetting or flowing air. Thus, the cooling space is the distance between the die and the jet or flow of air described above. Finally, in the present invention, the stretching temperature is preferably 10
It should be below 0 ° C, especially between 15 and 50 ° C. For more details on short-spinning equipment, see M.
Ahmed, “Polypropylene fibers science and technol
ogy ”, Elsevier Scientific Publishing Company (198
2) See pages 344-346. The spinning temperature in the long-spinning and short-spinning apparatus is generally 240.
C. to 310.degree. C., preferably 270.degree. C. to 300.degree.

The equipment used in the spun-bonding process is usually an extruder equipped with a die on the spinning head, a cooling tower,
And an aspirating and aspirating device using a Venturi tube. Under this device, which uses air velocities to control the rate of fiber accumulation, the filaments are typically collected on a conveyor belt where the fibers are dispersed and calendered to form a web for heat welding. In the present invention, the following process conditions are advantageously used when using a typical span-bonding machine. Hole flow rate is 0.1-2.
It is 0 g / min, preferably 0.2 to 1.0 g / min. Space where fibers are cooled and solidified after leaving the die (cooling space)
Is preferably more than 2 mm, more preferably more than 10 mm, especially 10-350 mm. The fibers are generally cooled by a jet or stream of air. Thus, the cooling space is the distance between the die and the jet or flow of air described above. The spinning temperature is generally 230 ° C to 300 ° C, preferably 240 ° C to 280 ° C.

In general, the olefin polymers which can be used in the process of the invention for producing heat-weldable fibers are R-CH = C in which R is a hydrogen atom or a C ₁ -C ₆ alkyl group.
H ₂ olefin polymers or copolymers, and mixtures thereof. Particularly preferred are the following polymers. 1) isotactic or predominantly isotactic propylene homopolymer, 2) propylene with a total comonomer content of 0.05 to 20% by weight, ethylene and / or 1-butene, 1-hexene , 1-octene, 4-methyl-1-pentene, crystalline copolymers with C ₄ -C ₈ α-olefins, or said copolymers with isotactic or predominantly isotactic propylene homopolymers 3) (A) a propylene homopolymer and / or one of the copolymers of 2), and (B) a copolymer of ethylene and propylene and / or a C _{4 to} C ₈ α olefin. Optionally butadiene, 1,4-hexadiene,
A heterophasic copolymer containing an elastomeric fraction containing small amounts of dienes such as 1,5-hexadiene, ethylidene-1-norbornene. The amount of diene in (B) is preferably 1-1.
It is 0% by weight. The heterophasic copolymer (3) is produced by mixing each component in a molten state or by sequential copolymerization by a known method, and generally the copolymer fraction (B) is contained in an amount of 5 to 80% by weight. Include in quantity.

Examples of olefin polymers which are particularly suitable for the production of heat-weldable fibers are the propylene random copolymers described below. a) 1.5 to 20% by weight of ethylene or C _{4 to} C ₈ α
Crystalline propylene random copolymer containing olefin, b) 85-96 wt% propylene, 1.5-5 wt%
Ethylene, and 2.5 to 10% by weight of C _{4 to} C ₈ α
Crystalline Propylene Random Copolymer Containing Olefin, c) (wt%) (1) Copolymer 3 of Propylene and C _{4 to} C ₈ α Olefin Containing 80% to 98% Propylene
0% to 65%, and (2) a copolymer of propylene with ethylene and optionally 2% to 10% of C ₄ -C ₈ alpha-olefin, not C ₄ -C ₈ alpha-olefin of the above are present In the case of containing 2% to 10% of ethylene, C ₄
When the -C ₈ alpha-olefin is present from 0.5% to 5%
A crystalline propylene random copolymer composition containing 35% to 75% of an ethylene-containing copolymer, d) a composition of a crystalline propylene random copolymer and a crystalline ethylene copolymer, wherein () (1)
And propylene, ethylene and / or C ₄ -C ₈ alpha 1 or more comonomers selected from olefins, the comonomer content is 5% to 20%, 40% of one or more crystalline copolymer 70 %, (2) MFR E (ASTM
LLDP according to D 1238) of from 0.1 to 15
A composition comprising E30% to 60%. The above copolymers can also be used in admixture with one another and / or with isotactic or predominantly isotactic propylene homopolymers.

Other examples of olefin polymers which are particularly suitable for the production of heat-weldable fibers are 5 to 95% by weight, isotactic or predominantly isotactic propylene homopolymers and / or a. ) -D) random copolymers, and 95-5% by weight of (I) (i) propylene homopolymer having an isotactic index greater than 90, or propylene greater than 85% by weight. Propylene and ethylene and / or other C ₄ with tactic index greater than 85
To C ₈ α-olefin crystalline copolymer, 10 to 60 parts by weight, (ii) 10 to 40 parts by weight of a crystalline polymer fraction containing ethylene, which is insoluble in xylene at room temperature, (iii) to xylene at room temperature. A composition which is soluble and contains 30 to 60 parts by weight of an amorphous ethylene-propylene copolymer fraction, optionally containing a minor amount of diene, comprising 40 to 70% by weight of ethylene, (II) (i) isotactic Propylene and ethylene and / or C containing propylene homopolymer having an index of more than 80 or propylene of more than 85% by weight.
_{4 to} C ₈ α-olefin copolymer, 10 to 50 parts by weight,
(ii) 5 to 20 parts by weight of a copolymer fraction containing ethylene, which is insoluble in xylene at room temperature, (iii) soluble in xylene at room temperature,
An intrinsic viscosity of 1.5 to 4 dl / g, an ethylene content of less than 40 wt%, optionally containing minor amounts of a diene, ethylene with propylene and / or C ₄ -C ₈ alpha copolymer fraction of olefins It is a heterophasic copolymer composed of a composition selected from the composition containing 40 to 80 parts by weight of the composition. Examples of C ₄ -C ₈ alpha-olefins and dienes are described above.

Generally, when used in the manufacture of staple fibers, the above olefin polymers are
Melt flow rate (MFR) measured by D 1238-L is 0.5 to 100 g / 10 minutes, preferably 1.
It is 5 to 35 g / 10 minutes. According to the method of the present invention,
When used in a bonding machine, the above-mentioned olefin polymer has an MFR value of preferably 5 to 25 g / 10 min, especially 8
~ 15 g / 10 minutes. These MFR values are another clear feature of the process of the present invention, since the MFR of polyolefins in the conventional spun-bonding process exceeds 25 g / 10 min. The above MFR values are obtained either directly during the polymerization or by controlled degradation. To carry out the controlled decomposition, for example, an organic peroxide is added to the spinning line or in the pelletizing step of the olefin polymer before that. The olefin polymer is generally used in the form of pellets or non-extruded particles such as flakes or spheres.

Preferably, the olefin polymer spun by any of the methods of the present invention is stabilized with a stabilizer of the type and amount described in Published European Patent Application No. 391438. According to that patent application, the spinning polyolefin comprises one or more of the following stabilizers: a) one or more phosphite and / or phosphonous ester, 0.01 to 0.5% by weight, b) one or more HALS (Hindered Amine Light Stabilization)
izer) 0.005-0.5% by weight, and optionally one or more phenolic antioxidants at a concentration not exceeding 0.02% by weight. The stabilizers described above can be added to the polyolefin by pelletizing or surface coating, or can be mechanically mixed with the polyolefin.

Examples of phosphites are from CIBA GEIGY
Tris (2,4-di-tert-butylphenyl) phosphite commercially available under the trademark Irgafos 168, BORG-WAR
ADEKA AR, a distearyl pentaerythritol diphosphite marketed under the trademark Weston 618 by NER CHEMICAL
4,4'-Butylidene bis (3-methyl-6-ter) phosphite marketed under the trademark Mark P by GUSCHEMICAL
t-butylphenyl-di-tridecyl), tris (monononylphenyl) phosphite, from BORG-WARNER CHEMICAL
Bis (2,4-di-tert-butyl) pentaerythritol diphosphite marketed under the trademark Ultranox 626. Examples of preferred organic phosphonates are Sa
Tetrakis (2,4-tert-butylphenyl) 4,4-diphenylene diphosphonate, commercially available from ndoz as Sandostab P-EPQ.

HALS are monomeric or oligomeric compounds containing in the molecule one or more substituted amines, preferably piperidine groups. HAL containing a substituted piperidine group
Examples of S are Chimassorb 944, Chim available from CIBA-GEIGY
assorb 905, Tinuvin 770, Tinuvin 992, Tinuvin 62
2, Tinuvin 144, Spinuvex A36, and American CYA
It is a product sold by NAMIDE under the trademark Cyasorb UV 3346.

Examples of phenolic antioxidants are American
Tris (4 sold by CYANAMIDE under the trademark Cyanox 1790)
-T-Butyl-3-hydroxy-2,6-dimethylbenzyl) -s-triazine-2,4,6- (1H, 3H,
5H) -trione, CIBA-GEIGY to Irganox 14
25, Irganox 3114, Irganox 1330, Irganox 1010, Irga
Calcium bi [monoethyl (3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate], 1,3,5-tris (3, commercially available under the trademark nox 1076.
5-di-tert-butyl-4-hydroxybenzyl)-
s-Triazine-2,4,6- (1H, 3H, 5H) trione, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) Benzene, pentaerythrityl-tetrakis [3
-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl 3- (3,5
-Di-tert-butyl-4-hydroxyphenyl) propionate], 2,6-dimethyl-3-abietic acid
Hydroxy 4-tert-butylbenzyl.

The following examples are provided to illustrate the invention and not to limit it. Evaluation of Thermal Weldability of Fibers In general, in order to evaluate the thermal weldability of fibers, a nonwoven fabric is produced from test fibers by calendering under certain conditions. The strength required to tear the nonwoven is then measured parallel to the direction of calendering as well as transversely. The strength value thus measured is considered to be a measure of the heat welding capacity of the fiber. However, the results obtained are that of fiber finishes (crimps, surface finishes, thermosetting,
Etc.) and the homogeneity of the distribution of fibers entering the calender. In order to avoid these disadvantages and to more directly evaluate the thermal welding properties of the fiber, the method described below was developed. 400 tex roving consisting of continuous fibers (method ASTM D 1577-
7), Prepare the sample from 0.4 meters in length. After twisting the roving yarn 80 times, both ends are put together to obtain a product in which half of the roving yarn are intertwined like one rope. The sample is heat-welded using a Bruggel HSC-ETK heat welder at a plate temperature of 150 ° C., a tightening pressure of 800 N and a welding time of 1 second. Use a dynamometer,
In the heat-welding area, the average strength required to separate the halves of the roving yarns that make up each sample is measured. The result obtained by averaging at least 8 measurements is expressed in Newton, and is the heat welding strength of the fiber.

[0020]Polymer spinning The polymers used to make the fibers in the examples are as follows:
is there.Polypropylene I Fraction soluble in xylene at 25 ° C with MFRL at 13 g / 10 min
Has a tailored particle size distribution with a content of 3.5% by weight
Flakes (average particle diameter 450 μm)
A mechanical mixture of homopolymers,Additive concentrationIrganox 1076 0.01% Irganox 3114 0.01% Irgafos 168 0.07% Calcium stearate 0.05%. The mechanical mixture consists of CACCIA
Put in a Kisa model LABO 30 and mix at 1400 rpm for 4 minutes.
It was obtained by combining.Polypropylene II It has the same composition as polypropylene I, but with the above mechanical
The mixture is in the form of pellets granulated by extrusion.Polypropylene III In the form of spherical particles with a diameter of 2-3 mm, the MFR is 12.2 g /
4.2% by weight of the xylene-soluble fraction at 10 minutes at 25 ° C.
Is a propylene homopolymer that is, Additive Concentration (by weight) Irganox 1076 0.01% Chimassorb 994 0.02% Sandostab P-EPQ 0.05% Calcium stearate 0.05%. Chimassorb 944 is a formula

[Chemical 1] And HA is generally 2-20.

Example 1 Using the above polypropylene I, Costruzioni Meccan
iche Leonard-Sumirago (VA) -Produces staple fibers on a LEONARD 25 long-spinning machine manufactured and marketed by Italy. The mechanism of the device is as follows. -Diameter 25 mm, length / diameter ratio 25, and flow rate 1-6
Extruder with kg / h screw-2.5 cm ³ / rev. metering pump-Die with 61 holes with 0.8 mm outlet diameter-Extruded by lateral air injection at temperature 18-20 ° C Cooling mechanism for filaments-Winding device with speed of 1000 to 6000 m / min-Drawing device in steam furnace The following process conditions are used for spinning operation. − Die temperature 280 ° C. − Hole flow rate 0.3 g / min − Accumulation speed 1400 m / min − Stretching ratio 1.3 − Stretching temperature 100 ° C. The characteristics of the fiber thus obtained are − Single fiber count 1.7 dtex (ASTM D 1577-79) -Weldability 4.1N

Comparative Example 1 Using the same polymer, equipment and conditions as in Example 1, but
The die has 61 round holes and the exit diameter is 0.4 mm. The properties of the fiber thus obtained are: -single fiber count 1.7 dtex-weldability 2.0 N

Example 2 Using the above polypropylene I, staple fibers are manufactured using a short-spinning pilot device having the following mechanism. -A single screw extruder with a diameter of 120 mm and a length of 30 times the diameter-a metering pump of 150 cm ³ /rev.-with 3.5 x 10 ⁴ round holes with an outlet diameter of 0.6 mm,
The hole is located in the form of a crown-a cooling mechanism which is coaxial with the crown of the hole of the die and discharges air at 20 ° C. in a plane perpendicular to the discharged fibers. Spinning conditions are as follows: . -Temperature 300 ° C-Hole flow rate 0.018g / min-Distance between cooling air flow 5mm-Integration speed 70m / min-Stretching temperature 80 ° C-Stretching ratio 1.4 The characteristics of the fiber thus obtained are- Fiber count 2.3 dtex-weldability 6.85N

Example 3 Staple fibers are prepared using the same equipment and conditions as in Example 2, but using polypropylene III. The properties of the fiber thus obtained are: -single fiber count 2.3 dtex-weldability 6.5N

Example 4 Staple fibers are prepared using the same polymers, equipment and conditions as in Example 2, but with a die to cooling air flow distance of 15 mm. The properties of the fiber thus obtained are: -single fiber count 2.3 dtex-weldability 7.6N

Example 5 A staple fiber is prepared using the same polymer, equipment and conditions as in Example 2, but the drawing is carried out at ambient temperature. The properties of the fiber thus obtained are: -single fiber count 2.3 dtex-weldability 10N

Comparative Example 2 Staple fibers are prepared using the same polymer as in Example 2, the same industrial equipment consisting of 8 spinning devices as in Example 2, but the die of the device is 0 outlet diameter. It has 5.18x10 ⁴ round holes of 0.4 mm. The spinning conditions are as follows. − Temperature 285 ° C. − Hole flow rate 0.018 g / min − Distance between die and cooling air flow 5 mm − Integration speed 64 m / min − Stretching temperature 80 ° C. − Stretching ratio 1.5 The characteristics of the fiber thus obtained are − Fiber count 2.3 dtex-weldability 2.35N

Comparative Example 3 Staple fibers are prepared using the same equipment and conditions as Comparative Example 2, but using polypropylene III. The spinning conditions are as follows. -Temperature 295 ° C-Hole flow rate 0.024g / min-Distance between cooling air flow and die 5mm-Assembly speed 70m / min-Stretching temperature 80 ° C-Stretching ratio 1.35 The characteristics of the fiber thus obtained are- Fiber count 2.3 dtex-weldability 2.2N

Example 6 Using polypropylene I, BARMER MASHINENFABRIK A.
Fibers are manufactured using the BARMAG 25 mod. 2E1 / 24D spun-bonding device manufactured and marketed by G. Manufacture. The mechanism of the device is as follows. -Diameter 25 mm, length / diameter ratio 25, and flow rate 0.3.
Extruder with ~ 1.2 kg / h screw-Measuring pump with 0.6 cm ³ /rev.-Die with 37 round holes with 0.8 mm outlet diameter-Temperature 18-20 ° C transverse air Cooling mechanism of extruded fibers by jetting-accumulation rate 500-400 using Venturi tube
Air suction type accumulator at 0 m / min The spinning process conditions are as follows. -Die temperature 280 ° C-Hole flow rate 0.6 g / min-Aggregation speed 2700 m / min-Distance between cooling die and cooling air jet 20 mm The characteristics of the obtained fiber are as follows. − Single fiber count 2.2 dtex − Weldability 5.4N

Comparative Example 4 Using the same polymer, equipment and operating conditions as in Example 6, but the die was equipped with 37 round holes with an exit hole diameter of 0.4 mm. The characteristics of the obtained fiber are as follows. − Single fiber count 2.2 dtex − Weldability 2.04N

Example 7 Polypropylene II is used to produce fibers and nonwovens in a pilot unit for spun-bonding manufactured by the German company LURGI. The mechanism of the device is as follows. -Rectangular die with 931 round holes with an exit hole diameter of 0.9 mm-Operating in a plane perpendicular to the fibers to be discharged, 20
Air cooling device at ℃ The spinning process conditions are as follows. -Temperature 280 ° C-Hole flow rate 0.52 g / min-Distance between die and cooling air flow 30 mm-Integration speed 2300 m / min The characteristics of the obtained fiber are as follows. − Single fiber count 2.3 dtex − Weldability 6.4N

Example 8 Fibers are prepared using the same equipment and operating conditions as in Example 6, but using polypropylene III. The properties of the fiber thus obtained are: -single fiber count 2.2 dtex-weldability 5.8N

Comparative Example 5 Fibers are prepared using the same polymer as in Example 8 and the same equipment as in Example 6, but the die has an exit hole diameter of 0.4 mm.
Includes 37 round holes. The properties of the fiber thus obtained are: -single fiber count 2.2 dtex-weldability 2.1N

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location D04H 1/54 C (72) Inventor Leonardo, Pinoca Italy Terni, Narni, Via, Santa, Croche, 1

Claims (14)

[Claims] 1. A process for producing heat-weldable polyolefin fibers, wherein the die used has a true or corresponding exit hole diameter of 0.5 mm or more, provided that the fiber has a count of 4 dtex or more. The method is characterized in that the ratio of the diameter of the exit hole to the count is 0.06 mm / dtex or more. 2. A true or equivalent exit hole diameter of 0.5-.
Method according to claim 1, characterized in that it is 2 mm. 3. The working process is carried out using a long-spinning device for staple fibers.
The method according to claim 1 or 2. 4. A hole flow rate of 0.15 to 1 g / min, a fiber collecting speed of 500 to 3500 m / min, and a draw ratio of 1.1 to 4.0. the method of. 5. Method according to claim 1, characterized in that the working steps are carried out using a short-spinning device for staple fibers. 6. A hole flow rate of 0.005 to 0.18 g / min, a fiber accumulation rate of 30 to 500 m / min, and a draw ratio of 1.10 to 10.
Method according to claim 5, characterized in that it is 3.50. 7. Method according to claim 5, characterized in that the cooling space is greater than 2 mm. 8. The method according to claim 5, characterized in that the stretching temperature used is below 100.degree. 9. Method according to claim 1, characterized in that the working step is carried out using a span-bonding device. 10. The method according to claim 9, wherein the hole flow rate is 0.1 to 2.0 g / min, and the fiber collecting speed is 400 to 4500 m / min. 11. Method according to claim 10, characterized in that the cooling space is greater than 2 mm. 12. The MFR of the olefin polymer to be spun is 5
Method according to claim 9, characterized in that it is -25 g / 10 min. 13. An olefin polymer to be spun, comprising: 1) an isotactic or predominantly isotactic propylene homopolymer; 2) a propylene having a total comonomer content of 0.05 to 20% by weight. Ethylene and / or C _{4 to} C ₈ α
A crystalline copolymer with an olefin, or a mixture of said copolymer with an isotactic or predominantly isotactic propylene homopolymer, 3) (A) propylene homopolymer and / or 2) A heterophasic copolymer comprising one of the copolymers and (B) a copolymer of ethylene with propylene and / or a C ₄ -C ₈ α-olefin, optionally containing an elastomeric fraction containing a small amount of dienes. Method according to any one of claims 1 to 12, characterized in that it is selected. 14. The olefin polymer to be spun comprises a stabilizer a) 0.01 to 0.5% by weight of one or more phosphite and / or phosphonous acid ester, and b) one or more HALS0. 005 to 0.5% by weight of at least one stabilizer, and optionally one or more phenolic antioxidants, in a concentration not exceeding 0.02% by weight. Item 1
14. The method according to any one of 13.