EP0755465B1 - Polyamide-66-monofilaments for precision fabrics - Google Patents

Description

The invention relates to dimensionally stable polyamide 66 monofilaments, with a titer of dtex 4f1-150f1, for Manufacture of precision fabrics.

Screen printing generally uses precision fabrics made of polyester (PET). The reason for this The preference for polyamide is the much higher one Modulus and the lower relaxation, d. H. less Tension loss of the tensioned screens, from PET. A high one Module of the precision fabric causes a higher one Process reliability in the clamping process as well as a higher one Printing precision through better clamping force. A minor one Relaxation has a positive effect on the service life of the Printing stencils.

The situation is different with direct tile printing. In This area works with pigment dyes, which are very abrasive. It is known that the Resilience of polyamide precision fabrics compared to these dyes is significantly higher than that the polyester precision fabric, so that the specific advantages and disadvantages of polyester and Approximately balance polyamide. For this reason In direct tile printing in addition to polyester in many cases Polyamide used. By optimizing the Fabric manufacturing has already been tried, the module and the relaxation behavior of polyamide fabrics in the direction To improve polyester fabrics significantly (H.P. Lisson, Serigraphy / screen printing practice 5/92, p.36-43). The polyamide fabric obtained has against the normal polyamide fabric certain improvements on this but are regarding the module and the Relaxation behavior of the monofilaments is still insufficient.

The object of the invention is to provide a monofilament To provide which is compared to the standard polyamide filament has a significantly higher module.

Another task is to relax, respectively. the To improve tension loss in the aqueous medium so that at least the level of polyester is reached.

Another task is to provide monofilaments which allow precision fabrics, especially for the direct tile and hollow body pressure with which desired properties without additional work step to manufacture.

The object of the invention is achieved in that the strength of the monofilaments from 60 to 71.1 cN / tex an elongation of less than 25%, the specific LASE, based on the initial titer, at 2% at least 7.5 cN / tex, at 5% at least 18 cN / tex and at 10% at least 40 cN / tex and the dry relaxation less than 25%.

It is surprising that with the inventive Monofilaments a precision fabric with a around 25% higher modulus (T 10 value) and one by about 50% state of the art improved relaxation behavior is achieved. The tissue obtained stands out also characterized by a very uniform product image, and there is a risk of warp thread breaks in the weaving mill greatly reduced.

The retardation gives the creep behavior of one thermoplastic monofilament again. Especially A retardation on the monofilament of less than 8%. A retardation of more than 8% in Monofilament leads to insufficient dimensional stability on the finished fabric.

Measurement methods:

Measuring the mechanical properties of the Monofilaments were made according to the standards DIN 53815 and DIN 53834.

The retardation (creep) of the filaments was measured by using a monofilament with a tension of 2.5 cN / dtex was loaded and then the elongation in function the time was recorded. The specification of the retardation takes place in percent, based on the initial length a delay of 120 minutes.

The relaxation of the filaments was in the dry state measured by a monofilament with a tension of 2.5 cN / dtex and then the Loss of voltage recorded as a function of time has been. The relaxation is given in percent, based on the output voltage after a relaxation time of 60 minutes.

The wet relaxation of the monofilament is measured based on the tensioning process and the subsequent one Use of a sieve in screen printing practice. Similar to when stretching a fabric on the stenter the Thread first and with one for 10 minutes constant specific force maintained at 2.5 cN / dtex (Elongation or retardation "dry"). Subsequently the actual measurement of the relaxation takes place by the Length of the thread kept constant and for 10 minutes the stress reduction is measured (relaxation "dry"). After this "dry phase" the threads become, always with the length kept constant, in water immersed, and after 30 minutes the Stress reduction registered ("relaxation wet"). The Difference in voltage measurements before and after Relaxation phase (10 min dry and 10 min wet) results the wet relaxation. The value is given in percent.

A wet relaxation of less than 25% is particularly advantageous.

In the K / D diagrams of fabric strips is the Curve shape, especially in the lower stretch range, strongly from the structure embossing in a fabric in warp and direction of fire. Depending on the web and Equipment conditions can e.g. the weft relative lie straight in the fabric, during which the warp thread a has strong wavy structure embossing. this leads to too different values, especially in the Reference forces. To compensate for the structural embossing conditional interaction between chain and Weft in the fabric should be used for determining the reference forces in the tissue always both directions resp. the arithmetic Means of warp and weft can be determined. Around to minimize the effect of structural embossing and a effectively corresponding to the thread properties To obtain the result, the tissue samples with a Preload force of 1.0 cN / dtex measured. The measurement was done on 5 cm wide strips of fabric and one Clamping length of 200 mm according to DIN specification 53 857.

The relaxation of a tissue in the wet medium was measured by using the various precision fabrics Sieves of 43 x 53 cm format were produced. Here the precision fabrics on the tensioner were set to 25 N / cm preloaded, then glued, sealed and stored for 5 days. Measurement of wet relaxation then followed. This was the output voltage of the template, measured on it for 24 hours placed in water and after the elimination of the Surface water the voltage was measured again afterwards. From the difference between the voltage measurements before and after Water relaxation results in wet relaxation. The value will stated in% voltage loss.

The invention is illustrated by means of examples become.

Embodiment 1 (thread production):

The threads made of polyamide 66 were with a Spinning speed of 320 m / min melt spun. With resulted in the total stretch ratio of 4.70 used a winding speed of 1510 m / min. The The temperature of the delivery godets was 70 ° C in each case The stretch godet was varied between 180 and 220 ° C.

Table 1 shows various variants with their most important process settings and thread properties. In addition, a standard polyamide monofilament (variant 1) was included in the investigation. variant 1 2nd 3rd 4th Stretching conditions: Total ver. [-] 4.0 4.7 4.7 4.7 Delivery temp. [° C] 70 70 70 70 Stretch temp. [° C] 180 220 220 220 Relax. Mating [-] 0.95 1.00 1.00 1.00 Winding speed [m / min] 1240 1510 1510 1510 Thread properties: Titer [dtex] 46.0 47.1 33.6 22.4 strength [cN / tex] 53.7 69.7 70.7 71.1 strain [%] 36.0 21.9 21.7 19.6 LASE 2% [cN] 25.9 38.1 31.0 22.2 spec. LASE 2% [cN / tex] 5.6 8.1 9.2 9.9 LASE 5% [cN] 52.6 95.1 72.8 55.3 spec. LASE 5% [cN / tex] 11.4 20.2 21.7 24.7 LASE 10% [cN] 125 208 160 121 spec. LASE10% [cN / tex] 27.2 44.2 47.6 54.0 KS [%] 6.4 7.7 8.2 8.1 TS 160 ° C [%] 3.7 4.8 5.1 5.2 TS 190 ° C [%] 5.1 6.4 6.5 6.4 Dry relaxation [%] 26.8 21.9 19.3 April 18 Wet relaxation [%] July 31 20.2 - - retardation [%] 10.5 6.2 6.6 6.3

Embodiment 2 (fabric production):

The production of the raw fabric (production stage 1) took place on standard weaving machines. Warp and Weft yarns are the same in diameter. The titer is 47 dtex.

In the finishing stage (manufacturing stage 2) the fabric in one or more thermal finishing steps treated in such a way that a Symmetry of the thread numbers in the weft and warp direction of +/- 1 thread / cm and a symmetrical force / elongation behavior result.

In a weaving test, thread variant 2 was used both in the warp and in the weft. Table 2 shows the reference forces arithmetically averaged from warp and weft directions at 10% (T10 value) and the wet relaxation of a finished precision fabric from thread variant 2 compared to a standard precision fabric (from thread variant 1). It can be seen that the precision fabric made of thread type 2 has an approximately 25% higher T10 value and an approximately 50% improved wet relaxation. variant 2nd 1 T10 value [daN / cm] 10.4 8.1 spec. T10 value [cN / tex] 36.3 28.7 Thread density [Threads / cm] 58 58 Wet relaxation [%] 8.5 16.2

A drawing is intended to further illustrate the results of the invention explain.

Show it:

Fig. 1 shows the K / D diagrams according to the invention Monofilaments compared to the known polyamide and polyester monofilaments.

Fig. 2 shows the corresponding retardation curves (creep).

Fig. 3 shows the relaxation behavior of the invention Monofilament

4 shows K / D diagram averaged over warp and weft of the precision fabric with the inventive Monofilament compared to the well-known polyamide precision fabric.

It can be seen from the K / D diagrams of FIG. 1 that the inventive type 2 compared to the standard PA6.6 Type 1 has a much higher module. Compared with the polyester it is clearly visible that the latter especially in the lowest area of stretching has a much steeper curve rise.

Figure 2 shows the retardation curves (creep) of PA standard Type 1 and the two monofilament types according to the invention 2 and 3. It can be seen that these with a Retardation of 6.2% resp. 6.6% are significantly better than the standard type with 10.5%.

The retardation curves were recorded by the Threads were loaded with a tension of 2.5 cN / dtex and then the elongation with time, given in % compared to the starting length.

Figure 3 shows the relaxation behavior under practical Conditions of the monofilament 2 according to the invention Compared to a standard polyamide 66 monofilament (PA66) 1 and a standard polyester (PET) monofilament 3. Before adding water, the monofilaments relaxed dry for 10 min. After Dry relaxation shows that according to the invention Monofilament with 2.8% clearly the least relaxation compared to the standard PA66 monofilament with 11.1% and PET with 9.1%. With the addition of water that shows monofilament according to the invention after 60 min Total relaxation (proportion of dry relaxation and proportion Wet relaxation) of 20.2% compared to 31.7% for Standard PA66 monofilament. The inventive Monofilament is also in the area of a polyester monofilament, which after the water treatment a Has total relaxation of 18.2%.

FIG. 4 shows the K / D diagram averaged over warp and weft of the precision fabric from the inventive Monofilament 2 compared to the well-known polyamide precision fabric 1 (fabric strips of 5 cm each Width). It can be seen that the module of the tissue from the monofilament 2 according to the invention that of the standard polyamide 66 fabric 1.

The polyamide monofilament according to the invention combines in excellent way, without chemical modifications of the Polymers, the properties required for screen printing a polyamide with that of polyester. It results in a LASE improved by about 40% at 2% and an approximately 35% improvement in wet relaxation compared to Standard polyamide 66 monofilament. The monofilament is for precision fabrics, preferably for use in Direct flow and hollow body pressure suitable.

Claims (3)

1. Dimensionally stable nylon-6,6 monofilaments having a linear density of 4f1-150f1 dtex for producing precision wovens, characterized in that the monofilaments have a breaking strength of 60-71.1 cN/tex, a breaking extension of less than 25 %, a specific LASE at 2 %, based on the original linear density, of at least 7.5 cN/ tex, a specific LASE at 5 %, based on the original linear density, of at least 18 cN/tex, a specific LASE at 10 %, based on the original linear density, of at least 40 cN/ tex, and a dry relaxation of less than 25 %.
2. Polyamide monofilaments according to Claim 1, characterized by a wet relaxation of less than 25 %.
3. Polyamide monofilaments according to Claim 1, characterized by a retardation of less than 8 %.

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