FR2680525A1 - FIBERS BASED ON PVC / PVC CHLORINATED MIXTURES WITH IMPROVED MECHANICAL PROPERTIES AND IMPROVED TENACITE FIBER YARNS OBTAINED FROM THESE FIBERS. - Google Patents

Abstract

Staple fibres based on an atactic PVC/superchlorinated PVC mixture in a proportion of 17 to 20 % of superchlorinated PVC, characterised in that they have a count of & 2.3 dtex and a residual shrinkage of & 6 % after treatment for 30 min in oil at 115 DEG C according to ASTM standard D 210262 T. Such fibres are suitable for producing threads of fibres of lower count which are sufficiently strong to be employed on high-speed weaving machines.

Description

FIBERS BASED ON MIXTURES PVC / PVC CHLORINE

  POSSESSING IMPROVED MECHANICAL PROPERTIES

  AND FIBER YARNS OF ENHANCED TENACITY

OBTAINED FROM THESE FIBERS

  The present invention relates to filaments, yarns, monofilament fibers and other similar articles of synthetic material consisting of polyvinyl chloride and chlorinated polyvinyl chloride It relates more particularly son and fibers of better mechanical qualities and fiber yarns of better

  tenacity obtained from these fibers.

  C It is already known according to French Patent 1,359,178 to prepare yarns and fibers consisting of mixtures of ordinary polyvinyl chloride and chlorinated vinyl chloride, the latter being present in a proportion of between 5% and 80%, preferably at least %. The fibers thus obtained can withstand heat treatment temperatures that are higher as the percentage of super chlorinated polyvinyl chloride in the mixture is high, which results in a decrease in the residual heat shrinkage. On the other hand, high percentages of superchlorinated vinyl significantly increase the cost price of the yarns and fibers obtained, especially since their production process is discontinuous,

  in particular the fixing heat treatment.

  French Patent No. 85 126/1 359 178 also recommends the use of blends of atactic polyvinyl chloride and chlorinated polyvinylchloride in a proportion of 5 to 50% of the mixture and specifies that the fibers obtained can, after spinning and drawing instead of being stabilized under tension under the conditions indicated in the main patent, they are directly shrunk by heating in a suitable medium, for example boiling water. In practice, however, the aforementioned treatment conditions make it impossible to obtain fibers with good properties only when the proportion of chlorinated polyvinyl chloride is relatively important In the sole example of this patent, the tenacities and elongations of the son obtained are good thanks to 2- the relatively large proportion of chlorinated polyvinylchloride: 20% In contrast, for lower chlorinated polyvinyl chloride levels and lower draw ratios, such qualities are impossible to obtain by direct shrinkage in boiling water Beyond 20% by weight of chlorinated polyvinylchloride, if the mechanical qualities of the fibers are much better,

  their cost price also increases accordingly.

  The difficulty with this type of atchloric polyvinyl chloride and chlorinated polyvinylchloride mixture therefore consists, in fact, to find a compromise to obtain fibers having the highest possible mechanical properties for the cost price

the weakest possible.

  It has also been found, according to French Patent No. 2,495,646, yarns and fibers based on a chlorinated PVC / PVC mixture, a minority of chlorinated PVC, for example between 16 and 20% already having improved mechanical characteristics, but whose However, the strength is insufficient to obtain fiber yarns capable of

  to be used on modern, high speed weaving machines.

  The yarns of the fibers obtained from the fibers described in French Patent 2 495 646 can be used only on low speed weaving machines or must be twisted to obtain twists from 2 spun yarns so as to possess the strength.

  enough to pass on the high-speed weaving machines.

  For the downstream textile industry, such use has a low economic interest in view of the increase in speeds

modern weaving machines.

  Moreover, the fibers obtained according to the French patent 2,495,646 have an insufficient and non-permanent curl,

  not allowing their passage to the card.

  Chlorinated PVC / PVC-based fibers having mechanical characteristics superior to those of the known prior art have now been found, a finer title, a permanent crimp, suitable for obtaining lower-titre fiber yarns. and sufficiently strong to be used on weaving machines

  high speed without going through the expensive preparation of a twists.

  3 - More particularly the present invention relates to fibers based on a chlorinated PVC / PVC mixture containing 17 to 20% of chlorinated PVC, of title to strand S 2,3 dtex, a residual shrinkage after treatment in oil at 115 C for 30 min (ASTM Standard D 210 262 T)

S 6%.

  Such yarns also have a modulus of elasticity k 4 = KN / mm 2, preferably k 5 KN / mm 2, elongation at break S 36%, preferably S 34%, fracture toughness 21 , 5 c N / tex, preferably 22 or even

more.

  The present invention also relates to a process for obtaining atopic polyvinylchloride and chlorinated polyvinylchloride-based fibers in a proportion of 17 to 20% by weight of superchlorinated PVC, by spinning a solution of the mixture. of polymer in a 60/40 solvent mixture of carbon disulphide / acetone in a manner known per se, stretching of the filaments in boiling water at a rate of between 3 and 6 X, continuous stabilization of the filaments under tension at a temperature between 125 and 140.degree. C., preferably 1350.degree. C. in the presence of steam at a pressure of 2.7 to 2.8 bar for 1 to 3 seconds, followed by mechanical or pneumatic crimping of the cable thus obtained in a known manner and treatment of fixing at a temperature of> 1000 ° C. in the presence of pressurized water vapor, continuously, then retraction in known manner in boiling water or by any appropriate means, then drying in a known manner continuously and in a punctured manner s shape

fiber.

  The present invention also relates to fiber yarns obtained from the fibers described above, having a good toughness, strand titles finer than those obtained so far and a

  better textile workability, especially in weaving.

  In particular, it is possible with the fibers according to the invention to obtain fiber yarns of metric number (NM) 50 (20 tex) which was not possible until then because the titles of the PVC / PVC superchlorinated fibers were too much to obtain sufficiently fine yarns of fibers For larger yarns of fibers, for example of NM -35 (50 tex) it was possible to obtain fiber yarns but their tenacity was insufficient According to the invention, the 4 spun yarns have a tenacity of at least 10 or 13 CN / tex which allows their weaving to

great speed.

  Atactic polyvinyl chloride is essentially homopolymer of vinyl chloride having a second order transition temperature generally between 65 and 85 ° C. Polyvinyl chloride is predominantly constituted by the atactic isomeric form, that is, that is to say that it is a polymer whose chlorine and hydrogen atoms are mostly randomly located on both sides of the chain constituting the skeleton of the molecule. As a result, such a poymère is normally Non-crystallizable nature Such a polymer is most commonly obtained in the least expensive manner by known mass, suspension or emulsion polymerization techniques at temperatures generally greater than OC, more generally

  between 20 and 600 C or even more.

  The chlorinated polyvinyl chloride that may be used according to the present invention may be obtained, for example, by chlorination of a suspension of polyvinyl chloride in the presence of actinic light, or by high temperature chlorination, or in the presence of active chemical radiation; it usually has a transition temperature

second order of at least 100 C.

  The staple fibers according to the present invention have mechanical properties and heat resistance never obtained until now, thanks to a selection of different elements. Firstly, the content of superchlorinated PVC in the superchlorinated PVC / PVC mixture of between 17 and 20%. preferably 18 to 20%, associated with the use of the solvent mixture carbon sulfide / acetone in a precise proportion 60/40 approximately achieves a better state of crystallinity of the polymer mixture This state of crystallinity is further improved by the treatments subsequent thermals, namely stretching in boiling water at temperatures between 85 and 1000 C, at a rate of between 3 and 6 X, preferably 3.5 X. The drawing of the filaments according to the present invention is generally preceded by preheating, for example in water, at temperatures between 60 and 100 ° C, more generally between 75 and

  850 C A convenient way is to use a heated water bath.

  The actual drawing can be carried out in 1 or 2 stages, but it is preferred to progressively raise the temperature of the filaments by preheating, pre-stretching for example in a bath whose water can be maintained between 70 and 950 ° C. and then continuously stretching at a temperature a little higher than that of the pre-stretching, preferably between 85 and 1000 ° C., or of overall stretching indicated above. In order to obtain an overall draw ratio of 6, it is easier to limit the drawing of the filaments. just after the die, by setting the speed of the rollers

of recovery.

  A second heat treatment which the filaments undergo contributes to fixing the structure of the filaments and to giving them their good properties, in particular the shrinkage in the oil at 1150 CS 6%, preferably at 5%, and to make it possible to obtain the titers stranded 2.3 dtex, preferably S 2.25 Due to a better crystalline state, this treatment can be carried out at higher temperatures than

  those usually supported by bleached PVC / PVC blends.

  It is carried out in the presence of steam, at a pressure of 1.3 to 3.6 bars, preferably 2.7 to 3 bars, at a temperature of

  between 120 and 1400 C, preferably 130 135 C for 1 to 3 seconds.

  The filaments thus stabilized are crimped by any known mechanical or pneumatic means, for example by means of a nozzle such as that described in French Pat. No. 83329 to FR No. 1,289,491. In such a nozzle, the filaments are treated with saturated water vapor at a temperature between 110 and 130-C and are simultaneously retracted and curled which allows a better

  later textile workability.

  To become permanent, and facilitate the passage to the card for example, the crimp thus produced must be set at high temperature, generally between 110 and 1200 C, in the presence of steam under pressure for at least 20 seconds, preferably at least

  seconds, and preferably continuously.

  For example, a commercial apparatus known under the trade name Towfix sold by S A Serracant can be used, which comprises a rotary closed drum on which the crimped filament cable is stacked, which are processed at the desired elevated temperature and

  continuously so that the process can be industrialized.

  The permanently curled filaments are then dried in the usual manner, generally at a temperature in the region of 1000 ° C. The process according to the present invention can be carried out completely continuously from the drawing or even from the dissolution of the polymers to obtaining the final yarns or fibers As a result,

  it is easy to produce industrially economically.

  The polymers or spun solutions according to the present application can contain usual fillers such as stabilizers vis-à-vis light, heat, brighteners, pigments, dyes likely to improve some of their properties such as their color, l dye affinity, thermal stability and light, (the electrical resistivity Such a process leads to fibers with better mechanical characteristics than those of son based on polyvinylchloride / chlorinated polyvinyl chloride mixtures obtained according to the French patent

2,495,646.

  In addition to heat shrinkage and low titrations, the values of fracture toughness and elongation at break are improved, which makes it possible to obtain fiber yarns which are much more efficient and have improved wearability They can also be used for the production knitwear, nonwoven articles, alone or in admixture with other fibers and in particular may undergo all treatments

  usual washing and dry cleaning under appropriate conditions.

  Said yarns and fibers according to the invention are also particularly preferred in the textile field because of certain properties inherent in the composition of the mixtures: non-flammability, resistance to light, chemical inertia and power.

  thermal, electrical and acoustic insulation.

  The following examples, in which the parties

  are by weight, are indicative but not limiting.

EXAMPLE 1

  A solution of polymer concentration of 28% by weight is prepared in a 60/40 carbon / acetone solvent mixture.

volume.

  The polymer consists of a mixture of% by weight of predominantly atactic polyvinyl chloride (AFNOR number: 120 according to AFNOR standard T 51-013 chlorine content 56.5%) and 20% of chlorinated polyvinyl chloride having a rate

  69% chlorine and an AFNOR index of 110.

  The solution thus obtained is filtered and, while being maintained at about 70 ° C., is spun through a die having 908 orifices of 0.06 mm in diameter in a dry spinning cell allowing the continuous recovery of the solvent mixture such that described in French Patent No. 913 927 The filaments are then C preheated in a water bath maintained at 800 C and then stretched a first time in a water bath maintained at 850 C at a rate of 3.15 X, then stretched a second time in a second water bath maintained at 100 ° C at a rate of 1.2 X (total rate 3.78 X) The filaments are then stabilized continuously under tension in a tube containing 125-saturated steam C under a pressure of 2.32 bar, the input and output speeds of the filaments being strictly identical, and the residence time in the

tube being 2 seconds.

  The filaments then undergo mechanical crimping and free shrinkage in a nozzle as described in French Patent No. 83,329 to FR No. 1,289,491 at 120 ° C. in the presence of steam. The filament cable is then sprayed in a device known commercially under the trademark Tow Fix of the Anonymous Company Serracant, continuously, at a temperature of 1100 C for 30 seconds, the cable being treated in a densified form at 450 kg / m 3 It is then dried in the usual way in an oven at 105 ° C and will be

  cut to obtain staple fibers in the usual way.

  The results of fibers obtained are summarized in Table 1 below. -35 -8-

Example 2

  Example 1 is reproduced with the exception of the fixing treatment, which is carried out under tension in the presence of steam at C under a pressure of 2.7 bar. The characteristics of the fibers

  obtained are shown in Table 1.

Example 3

  Example 1 is reproduced with the exception of the fixing treatment which is carried out under tension in the presence of steam at 135 ° C. at a pressure of 3 bar. The characteristics of the fibers are given in the table below; the tests corresponding to Examples 1 to 3 were carried out compared with control fibers obtained according to French Patent No. 2,495,642 from a 17.5% chlorinated PVC / PVC mixture or superchlorinated PVC in a sulfide mixture. of carbon / acetone 50/50, spun and stretched in the same way, the filaments being subjected to a thermal fixing treatment in the presence of water vapor carried out at 113 ° C., under a pressure of 1.7 bars, and then curled in a nozzle as in Example 1 and dried at 1050 C.

TABLE 1

C 25

  Example 1 Example 2 Example 3 Strand Control 2.3 2.26 2.22 2.7 Residual C Removal in Oil% 6.14 12 Toughness CN / tex 21.8 22.3 22 , 9 18 elongation% 36 34 31 65 Young's modulus KN / m 2 5.2 5.35 5.41 2.8 shrinkage stress -2 g / dtex 2.4 2.5 2.6 1.5 shrinkage outlet nozzle% 4 3 2 2 final packing% 15 13 il he 9 - The shrinkage stress which expresses the degree of orientation of the yarns is measured by means of a retractometer: the filament samples of length 4 cm, assembled in the form of Test specimens of 400 dtex on average (each test being carried out on two specimens) are subjected, after each of the various stages of stretching, stabilization and finally retraction, to a temperature rise of 1 C per minute, of 30 ° C. at 1700 C. The retraction force expressed in 10-2 g / dtex is measured on each specimen as a function of the temperature. This withdrawal constraint or withdrawal force in each case passes through a maximum at a certain temperature It is this maximum withdrawal force that represents the orientation characteristic

  product, which is referred to as shrinkage stress.

  Filling (or crimp rate) determined on INSTRON 1122 A fiber whose title has been determined is subjected to a tensile test until it reaches a completely relaxed state,

  (detection on the force / elongation curve).

  On this curve, certain points are noted for the calculation of the following values: Stretch length Curly length Embossing% = x 100 Stretch length From the fibers obtained according to Example 2, yarns of fibers are prepared whose characteristics are as follows: invention witness the invention witness

NM 20 NM 50

  Title (tex) 51,81 52,1 19,65 impossible to NM 19,30 19,19 50,88 realize

CV Uster% 9.57 12.19 15.10 -

Imperfections over 1000 m:

- fine points 0 O 27 -

big points 2 10 43 -

buttons 3 6 68 -

  breaking force (c N) 696 416.8 208.4 -

  CV breaking strength 6.14 18.8 10.36 -

Lengthening to

rupture% 26.7 29.3 21.25 -

Toughness at break

c N / tex 13.4 8 11.43 -

((11 -

Claims (5)

  1 Chopped fibers based on an atactic PVC / chlorinated PVC mixture containing 17 to 20% of superchlorinated PVC, characterized by the fact that they have a titre on strand S 2,3 dtex and a residual shrinkage after treatment in the oil at 1150 C for 30 min according to ASTM D 210262 T S 6%.   2 cut fibers according to claim 1 characterized by   the fact that they have an elongation at break S 36%.   C 3 cut fibers according to claim 1 characterized by   the fact that they have a fracture toughness 21 21 CN / tex.   4 cut fibers according to claim 1 characterized by   the fact that they have a modulus of elasticity k 4 KN / mm 2.   Process for obtaining cut fibers according to Claim 1, characterized in that a solution of a chlorinated PVC / PVC mixture of 17-20% of PVC is spinned by a dry spinning process in a known manner. superchlorinated in a solvent mixture of carbon disulfide / acetone in a proportion of about 60/40 by volume, which is stranded in boiling water at a rate between 3 and 6 X, stabilized continuously under tension at a temperature between 125 and 1400 C in the presence of water vapor under absolute pressure of 2.3 to 3.6 bar for 1 to 3 seconds, which is mechanically frieze the cable thus obtained in a known manner, that the crimping is continuously fixed at a temperature of 2100 ° C. in the presence of pressurized water vapor, the filaments being then retracted and then dried from   usual way, continuously and cut in a known manner.   Process according to Claim 5, characterized in that the filaments are stabilized under pressure at a temperature of between 130 and 135 ° C under an absolute pressure of between 2.7. -35 and 3 bar.   12 - 7 Process according to claim 5 characterized by the fact   that the crimp is set at a temperature between 110 and 125 ° C.   8 Fiber-based fiber yarns from chlorinated PVC / PVC blends containing 17-20% chlorinated PVC having a number   Metric 2 and fracture toughness 2 10 CN / tex.