JPS59626B2 - Method of improving tear strength properties of needled spun fleece - Google Patents

Description

Detailed Description of the Invention The present invention provides a spun fleece (S) made of thermoplastic synthetic resin.
The present invention relates to a method for improving the properties of pineapple (pinnvliese), in particular its tear strength properties.

BACKGROUND OF THE INVENTION Spun nonwovens, which are composed of virtually endless, almost stitched, threads of thermoplastic synthetic resin, have been known for quite some time.

They are mostly produced by depositing the yarns immediately after spinning and after their primarily air drawing. Depending on the deposition method used, the degree of presence of parallel future residues also varies. Since the ideal fully non-oriented seam condition is rarely achieved, such fleeces almost always have a higher tear strength in one direction compared to the direction perpendicular to it. . However, some applications, such as underground construction, are concerned with strength in all directions rather than in one direction. This means that in that application a minimum tear strength becomes the norm and the thickness of the fleece must therefore also be selected according to the minimum tear strength. However, this means an increase in the price of fleece, which precludes its large-scale use. German Patent Application No. 2,639,466 discloses that the nature of stable fiber fleeces, whose individual fibers are oriented transversely to the main width of the fabric, is such that these fleeces are first oriented in the longitudinal direction. Improvement is described by stretching, then needling, then stretching once more in the machine direction and finally in the transverse direction.

This increases the dimensional stability and strength of the fleece. Additionally, German Patent Application No. 22
39058, having relatively short fibers,
A regular pattern is applied to an unsecured stable fiber fleece in the sewn state using mechanical or fluid forces by stretching it in the transverse direction and crimping it in the longitudinal direction at the same time. It is known that lateral tear strength can be improved without compromising the regular thick and thin pattern.

In fact, it can even be completely repaired by another post-treatment using fluid forces that cause reorientation of relatively short fibers. Finally, according to DE 16 35 634 A1, panelization (Ti
It has been proposed to improve the tear strength in the machine direction by stretching a fleece which has strong orientation in the transverse direction by stretching it in the machine direction during needling.

Simultaneously uncontrolled lateral protrusion (Quereins)
This stretching (Recku
ng) The fuzz of the fibers, which lie at an angle of 10-15° to each other in the panel (Tifler), is so twisted during the initial needling that the fibers end up lying at an angle of 45°. This would result in it being fixed. This process, which can only be carried out by breaking it down into many individual small drawing stages during needling, requires a large amount of equipment expenditure. Because, after all, Ni-
This is because dollar processing machines must be operated with small puncture speeds and high exit speeds, which also have to be varied. This is because otherwise stripes will appear on the fleece. It is also shown in this German patent application that it is not possible to stretch the panel fleece only once, since thin sections are formed which tear during subsequent stretching. There is. Endless yarn fleece (EndlOsfadenvli)
ese), stretching has already been proposed to improve the properties.

According to German Patent Application No. 1900265, the nonwoven fabric fused or glued at the intersections is stretched in at least one direction until its surface area is enlarged by a factor of about 15. In the case of the nonwovens used in this method, the intersecting parts are rigidly fixed, so that the drawing of the individual yarns, which vary considerably in the individual fineness, is achieved in this way, with the The variation in fineness is
Obtained with 10 ducks. In this case, stretching is carried out with heated brake shoes. The inventors have determined that the tear strength of a spun fleece in which the yarns are in a nearly sewn state can be improved by stretching the needled fleece using high temperatures in the direction that has a relatively low tear strength. As a result, the tear strengths in directions that are successively located perpendicular to each other can be brought closer to each other, with the lower tear strength in one of the two directions being significantly improved. discovered that the fineness of the yarn could be improved to non-uniformity without the yarn itself being stretched.

By this means, the tear strength is at the same time 1771
The fact that a relatively high minimum tear strength is nevertheless obtained means that the use of fleece is now practically economical, especially for paving. This opens up possibilities in civil engineering works such as tunnels, sea walls, and waterway construction, since in this case not only the Kerr elongation properties but also the weight of the fleece per 177! ,
Therefore, a larger area can be obtained using the same weight of fleece material. The fact that a need-linked fleece with unsecured intersections is strengthened without loosening is surprising.

This is because it was expected that in some cases, the existing slightly thin portion would deteriorate or become perforated. However, this is not the case in this case; on the contrary, the threads in the stitched state are relatively evenly distributed, with the loop-shaped threads having an increasingly increasing degree of drawing changing into the drawn state; This gives greater strength to the fleece. However, all this is only achieved if the drawing is carried out in a certain temperature range, which depends on the melting point of the crystallite. The subject of the invention is therefore a spun fleece consisting of a thermoplastic synthetic resin, the threads of which are approximately in the state of a weave and which exhibit a higher tear strength in one direction than in the direction perpendicular thereto. and said fleece is produced by melt-spinning yarns, drawing and immediately subsequent laying and fixing the fleece so formed by needling. In a method for improving the tear strength properties of a spun fleece, the spun fleece is subjected to 20 to 200% of its initial length in a direction with relatively low tear strength at a temperature of 85 to 25° C. below the melting point of the crystallite. The method is characterized in that the length is maintained in the perpendicular direction or this length is varied in advance or simultaneously within a range of ±10% of the initial length.

A prerequisite for the success of the method according to the invention is to start from a fleece fixed by needling.

In order to obtain good properties, especially at relatively high elongation rates, it is advisable to choose a less light needling. It is preferred to start with a fleece that has been needled until its strength increase due to needling reaches at least 50% of the optimal strength increase obtained by needling. For example, when using 15 x 18 x 34 type needles per 3 inches, it is about 10
At 0 stabs/Cd and 15 x 18 per 3 inches
120 stitches/CrA when using a ×36 type needle
Obtained in Particularly advantageous results are around 180-20
Obtained when using a fleece treated with needles of the above type with 0 stabs/Cd. Endless yarn fleeces of the type mentioned above usually have a relatively low tear strength in the transverse direction.

According to the invention, these fleeces are stretched transversely to the extent according to the invention, for example in tension frames known per se. However, if the fleece is placed on a disk with teeth around its periphery, the surface of these teeth being almost perpendicular to the surface of the fleece and arranged at an acute angle to the running direction of the fleece, the fleece It is also possible to use a stretching machine in which the material is stretched as it passes around the circumference of the disk.

Such a device is described, for example, in German Patent Application No. 240
It is described in No. 1614. However, if the endless yarn fleece is brought to a certain thickness by paneling before needling, it is mostly in the machine direction that it has a lower tear strength.

In this case, the nonwoven must be stretched in the machine direction, which can be carried out particularly advantageously, for example, by a roller stretching method known per se with short roller slits. However, any other known machine direction stretching method can be used, provided that the fleece does not bend too strongly inwards in order to maintain the scope according to the invention. This can be done, for example, by providing several zones between the longitudinal stretching zones, in which the fleece is stretched in the transverse tensioning device to a width prescribed by the invention, which must be within ±10% of the initial width. can do. Even in the case of panelized fleece, the drawing process according to the present invention is affected by the stitching state of the endless threads.
The drawing process according to the invention, even when using panelized endless yarn fleeces, is independent of the fact that the individual fibers lying at an angle towards the panel are not oriented. (The above angles are from German Patent Application No. 163)
5634, as obtained during needling during drawing of the stable fiber nonwoven). The selection of the degree of stretching within the scope according to the invention should be made according to the desired values. For example, if it is desired to increase the tear strength in the weaker direction by, for example, 15 to 20% without compromising the strength in the machine direction, it is preferable to choose a light stretch of 20 to 30%. The higher the degree of stretching in the weak direction, the lower the tear strength in the stronger direction, so that for example in the case of a stretch of 60-100%, a fleece is obtained which is almost isotropic with respect to tear strength and its The tear strength is in the range intermediate between the initial longitudinal strength and the transverse strength. The lowest tear strength depends on the intended use, so that this nonwoven is subjected to higher loads following the treatment according to the invention than the starting nonwoven. The method according to the invention can be applied to endless yarn nonwovens made of all thermoplastic synthetic resins, such as polyamides, polyesters, polyolefins.

Particular preference is given to fleeces made of propylene homopolymers and copolymers and polyesters. The method according to the invention will be explained in more detail with reference to the following examples. The stated tear strength and elongation at break values are DIN
53857. Example 1 The following data are as follows: Yarn fineness: 11 Dtex Surface weight: 240 y/m" Needling: 60 stitches/Cd Needled endless yarn made of polypropylene having a tear strength of 640 N in the machine direction, an elongation rate at break of 85% in the machine direction, a tear strength of 305 N in the transverse direction, and an elongation rate of 120% in the transverse direction at break. The fleece is stretched on a tension frame and stretched by 20% in the transverse direction while running continuously at a temperature of 130° C. without drafting in the longitudinal direction.

After exiting the hot air oven, the fleece is removed from the tension frame and rolled up continuously. It has the following data: areal weight 2
20V/m'' Tear strength: 653N in the longitudinal direction Tear strength: 352N in the transverse direction Elongation at break: 61% in the longitudinal direction Elongation at break: 84% in the transverse direction Therefore, this fleece has a tear strength of only 50N at a nearly constant longitudinal tear strength Has increased lateral strength.

In contrast, 220 manufactured according to the usual spinning method
An unstretched fleece with an areal weight of y/771" has the following data: tear strength machine direction 60
0 N Tear strength: 245 N in the transverse direction Elongation at break: 90% in the machine direction Elongation at break: 130% in the transverse direction Thus, the fleece produced according to the invention is outstanding in terms of tear strength.

Example 2 The same fleece as described in Example 1 is transferred to a tension frame and stretched at room temperature at a rate such that it is stretched by 10% in the machine direction before the side edges are captured by holders.

Next, it is stretched by 20% in the transverse direction at 130°C.
The fleece obtained after removal from the tension frame and cooling has the following data: areal weight 208 V/m” tear strength machine direction 624 N tear strength transverse direction 348 N elongation at break machine direction 57% elongation at break In contrast, an endless yarn fleece produced by spinning and deposition of polypropylene with an areal weight of 200 V/wl has a tear strength of 570 N in the machine direction and a tear strength of 230 N in the transverse direction. and vertically 90
% and an elongation at break of 135% in the transverse direction.

The data below are as follows: Yarn fineness: 10 dtex Area weight: 290 y/m" Tear strength: 690 N in longitudinal direction Elongation: 91% in longitudinal direction Tear strength: 357 N in transverse direction Elongation: 139% in transverse direction - Needling: 180 stitches/Cd A strongly needled endless yarn fleece made of polypropylene having a strength of 15 x 18 x 34/3 inch C.b. Stretched in the transverse direction by 40% at 135° C. without any heat.

After cooling, this fleece has the following data: areal weight 2
30y/Tri'' Tear strength in machine direction 558 N Elongation in machine direction 76% Tear strength in transverse direction 438 N Elongation in transverse direction 84% On the contrary, it has an areal weight of 230 V/Trl produced similarly to the fleece used as starting material The fleece has a tear strength of 650 N in the machine direction and 290 N in the transverse direction and an elongation at break of 85% in the machine direction and 125% in the transverse direction.

Example 4 The following data: yarn fineness 10 dtex initial weight 240 V/m” needling 200 stitches/Cd (15 x 18 x 36/3 inch C.b. needle corresponding to 85% of the optimum strength below) ) Tear strength longitudinal direction 656
A fleece made of polypropylene having an N elongation rate of 85% in the longitudinal direction and a tear strength of 310N in the transverse direction and an elongation rate of 136% in the transverse direction is stretched in the transverse direction by 60% at 135°C using a tension frame without previously applying a draft in the longitudinal direction. .

The fleece obtained in this way has the following data: areal weight 188 V/m” tear strength in the machine direction 490 N elongation in the machine direction 75% tear strength in the transverse direction 364 N elongation in the transverse direction 51% compared to the starting fleece A fleece made in a similar manner but with an areal weight of 180 V/Cd is 530 V/Cd.
It has a longitudinal strength of N and a transverse strength of 200 N and an elongation at break of 95% in the machine direction and 150% in the transverse direction.

Example 5 The fleece described in Example 4 was heated at 140°C.
It is stretched by 0% in the transverse direction, during which it is simultaneously crimped by 10% in the machine direction.

Thereby, a fleece is obtained with the following data: areal weight 195 V/m'' tear strength longitudinal 502 N tear strength transverse 389 N finished elongation 78% in the machine direction elongation 50% in the transverse direction compared with the starting fleece A fleece manufactured in a conventional manner but with an areal weight of 200V/771' has a longitudinal tear strength of 570N, a transverse tear strength of 230N and an elongation at break of 90% in the machine direction and a transverse It has an elongation at break of 135% in the direction.

Example 6; 3- The following data are as follows: Thread fineness 11Dtex Surface weight 386y/Cwi Tear strength Longitudinal direction 1139N Elongation rate Longitudinal direction 110% Tear strength Lateral direction 514N Elongation rate Lateral direction 152% Needling 120 punctures/Cd (needle A needled endless yarn fleece made of polypropylene having a pattern of 15 x 18 x 36/3'' C.b. (one stamp) was stretched on a tension frame and allowed to run continuously without applying a draft in the longitudinal direction in advance. 100% in the transverse direction.

After leaving the hot blast oven, this fleece has the following data: areal weight 216 V/wl' tear strength longitudinal direction 701 N elongation longitudinal direction 51% tear strength transverse direction 545 N elongation transverse direction 82% tear strength longitudinal direction: The first large difference of 2.2:1 in the transverse direction is due to the stretching process, which results in a difference of 2.2:1 in the longitudinal direction:-1.
The transverse tear strength after stretching of the fleece, averaged to a ratio of 2:1 and now lighter by 44% by weight, increased by 6% from 514N to 545N.

Example 7 The following data are as follows: Thread fineness: 11Dtex Area weight: 238V/771″ Tear strength: 600N in longitudinal direction Elongation: 107% in longitudinal direction Tear strength: 320N in transverse direction Elongation: 146% in transverse direction Needling: 120 punctures/Cd (needle type: 15 × 18 Stretch it.

After leaving the hot air oven and cooling, this fleece has the following data: surface weight 112 V/w? Tear strength: 400 N in the longitudinal direction Elongation: 39% in the longitudinal direction Tear strength: 240 N in the transverse direction Elongation: 82% in the transverse direction When the surface weight is reduced by 53%, the tear strength in the longitudinal direction is 33%, and the tear strength in the transverse direction is 25% reduction, the machine:transverse tear strength ratio averaged from 1.87:1 to 1.66:1.

Example 8 The following data are as follows: Thread fineness: 11Dtex Area weight: 184V/771" Tear strength: 503N in longitudinal direction Elongation: 94% in longitudinal direction Tear strength: 224N in transverse direction Elongation: 133% in transverse direction Needling: 120 stitches/m" (needle type) 15 x 18 x 36/3" C.b. 135" without prior longitudinal stretching in the tension frame.
It is stretched in the transverse direction by 140% at .

After leaving the hot air oven and cooling, this fleece has the following data: areal weight 86y/a tear strength machine direction 285N elongation rate machine direction 39% tear strength transverse direction 171N elongation rate transverse direction 76% area weight 55% When the tear strength in the machine direction is reduced by 43% and the tear strength in the transverse direction is reduced by 25% by the stretching process, the ratio of the machine direction: transverse direction tear strength is 2. Averaged from 2:1 to 1.66:1.

Example 9 The following data are as follows: Thread fineness: 11Dtex Area weight: 298y/771″ Tear strength: 620N in longitudinal direction Elongation: 101% in longitudinal direction Tear strength: 320N in transverse direction Elongation: 163% in transverse direction Needling: 120 punctures/Cd (needle type: 15 × 18 × 36/3″ C.
180% transverse stretching was carried out at a temperature of 35°C.

After cooling, this fleece has the following data: Area weight 116 f/m Tear strength 480 N in machine direction Elongation 29% in machine direction Tear strength 260 N in transverse direction Elongation 102% in transverse direction When reducing areal weight by 62% After the stretching process, the tear strength in the machine direction decreased by only 33%, the tear strength in the transverse direction decreased by only 36%, and the ratio of tear strength in the machine direction: transverse direction was
It averaged out somewhat from 1.93:1 to 1.84:1.

Example 10 The following data are as follows: Yarn fineness Ildtex Area weight 1841/m'' Tear strength Longitudinal direction 503N Elongation rate Longitudinal direction 94% Tear strength Lateral direction 224N Elongation rate Lateral direction 133% Needling 120 stitches/cm (needle type 15 x 18 x 36 x 3'' C.b. one stamp) was placed in a tension frame with a draft of 10% in the lengthwise direction.
Stretched by 140% in the transverse direction at 5°C.

After cooling, this fleece has the following data: areal weight 82V/771″ tear strength machine direction 290N elongation machine direction 37% tear strength transverse direction 168N elongation transverse direction 78% When reducing areal weight by 66% The tear strength in the machine direction is reduced by only 42% and the tear strength in the transverse direction is reduced by only 25% by the stretching process, whereas the ratio of the tear strength in the machine direction: transverse direction is 2.25: 1 to 1.7
The ratio was averaged to 2:1.

Example 11 The following data: Yarn fineness Ildtex Area weight 184'F7/m'' Tear strength Longitudinal direction 503N Elongation rate Longitudinal direction 94% Tear strength Lateral direction 224N Elongation rate Lateral direction 133% Needling 180 stitches/Cd (Needle type The needled fleece according to Example 1 with dimensions 15 x 18 Stretch.

After cooling, this fleece has the following data: areal weight 91 y/m'' tear strength machine direction 281 N elongation machine direction 42% tear strength 'transverse direction 175 N elongation transverse direction 73% with 51% reduction in areal weight The tear strength in the machine direction decreased by only 44%, and the tear strength in the transverse direction after the stretching process decreased by only 22%, whereas the ratio of tear strength in the machine direction: transverse direction was 2.25:1 to 1.
Averaged up to 60:1.

Example 12 The following data: Thread fineness 10 dtex Area weight 230 y/'m Needling 200 stitches/Cd (Needle type 15 x 18 which corresponds to 85% of the following optimal strength value obtained by needling) × 36/3″C.b) Needled endless yarn made of polypropylene having tear strength: 620N in the machine direction, elongation at break: 90% in the machine direction, tear strength: 280N in the transverse direction, elongation at break: 150% in the transverse direction. The fleece was stretched in a tension frame without drafting in the machine direction and stretched by 80% in the transverse direction with continuous running at a temperature of 135°C.

After passing through the hot air oven, the fleece was removed from the tension frame and rolled up continuously. This fleece has the following data: Area weight 150 y/m" Tear strength 420 N in the machine direction Elongation at break 75% in the machine direction Tear strength 340 N in the transverse direction 57% elongation at break On the contrary, the conventional spinning method 150y/m” manufactured
An unstretched fleece with an areal weight of has the following data: tear strength machine direction 470 N elongation at break machine direction 95% tear strength transverse direction 180 N elongation at break transverse direction 150% 230 y/rl- The same fleece having an areal weight of l has been stretched by 10% in the longitudinal direction at room temperature beforehand.
If stretched by 80% in the transverse direction at 136° C., a fleece with the following data is obtained: areal weight 1
65y/Rrl Tear strength: 435N in the longitudinal direction Elongation at break: 70% in the longitudinal direction Tear strength: 356N in the transverse direction Elongation at break: 52% in the transverse direction

Claims (1)

[Claims] 1. A spun fleece made of a thermoplastic synthetic resin,
The yarn is generally in a weave and has a higher tear strength in one direction than in a direction perpendicular thereto, and the fleece is melt-spun, drawn and immediately subsequently laid down and In a method for improving the tear strength properties of a needled spun fleece produced by subsequently fixing the so-formed fleece by needling, said spun fleece is coated with crystallites. At a temperature of 85-25° C. below the melting point, it is stretched by 20-200% of its initial length in a direction with relatively low tear strength, keeping the length in the direction perpendicular to the above, or A method characterized in that the length is varied in advance or simultaneously within a range of ±10% of the initial length. 2. Starting from an endless yarn fleece that has been needled to such an extent that more than 50% of the optimum strength increase obtained by needling is obtained by needling. Method. 3 Starting from an endless yarn fleece that has a higher tear strength in the machine direction than in the cross direction and stretching this fleece by 20-200% in the cross direction,
A method according to claim 1 or 2. 4 Starting from a panelized endless yarn fleece having a higher strength in the transverse direction than in the machine direction and stretching this fleece by 20 to 200% in the machine direction The method described in.