EP0530119B1 - Fibres from a mixture of PVC and chlorinated PVC with improved mechanical properties and staple yarns with improved tenacity made from these fibres - 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

The present invention relates to filaments, threads, fibers monofilaments and similar synthetic articles made of polyvinyl chloride and polyvinyl chloride superchlorinated. It relates more particularly to yarns and fibers of better mechanical qualities and better fiber yarns toughness obtained from these fibers.

It is already known according to French patent 1,359,178 from prepare yarns and fibers made from mixtures of polychloride regular vinyl and superchlorinated polyvinyl chloride, the latter being present in a proportion of between 5% and 80%, preferably at least 10%.

The fibers thus obtained can withstand temperatures the higher the percentage in polyvinyl chloride superchlorinated in the mixture is high, which has as a consequence a reduction in the residual thermal shrinkage. By against, high percentages of superchlorinated polyvinyl chloride significantly increase the cost price of yarns and fibers obtained, all the more so since their production process is discontinuous, in particular the heat treatment of fixing.

French patent n ° 85.126 / 1.359.178 also recommends the use of mixtures of atactic polyvinyl chloride and polyvinyl chloride superchlorinated in a proportion of 5 to 50% of the mixture and specifies that the fibers obtained can, after spinning and drawing, at place to be stabilized under voltage under the conditions indicated in the main patent, be directly shrunk by heating in a suitable medium, for example boiling water. But, in practice, above-mentioned processing conditions do not allow fibers to be obtained good properties only when the proportion of polyvinyl chloride superchlorinated is relatively large. In the unique example of this patent, the toughness and elongation of the threads obtained are good thanks to the relatively high proportion of polyvinyl chloride superchlorinated: 20% by weight. On the other hand, for polychloride contents lower chlorinated vinyl and lower draw rates, such qualities are impossible to obtain by direct retraction in the boiling water. Above 20% by weight of polyvinyl chloride superchlorinated, if the mechanical qualities of the fibers are much better, their cost price also increases accordingly.

The difficulty with this type of polyvinyl chloride mixture atactic and superchlorinated polyvinyl chloride therefore consists, in fact, of find a compromise making it possible to obtain fibers having the highest possible mechanical qualities for the cost price as low as possible.

It was also found according to the French patent No. 2,495,646 yarns and fibers based on a PVC / chlorinated PVC mixture, minority in chlorinated PVC, for example between 16 and 20% already improved mechanical characteristics, but whose resistance is however insufficient for obtaining capable fiber yarns to be used on modern weaving machines, at high speed. Yarns of fibers obtained from the fibers described in patent French 2,495,646 can only be used on weaving machines at low speed or must be twisted to obtain plied from 2 yarns of fibers so as to have the resistance sufficient to pass on high speed weaving machines.

For the textile industry, such use has low economic interest given the increase in speeds modern weaving machines.

In addition, the fibers obtained according to the French patent 2,495,646 have insufficient and not permanent crimp, do not not allowing their passage to the card.

PVC / PVC based fibers have now been found superchlorinated with mechanical characteristics superior to those from the known prior art, a finer title, a permanent crimp, suitable for obtaining yarns of lower titer fibers and strong enough to be used on weaving machines high speed without going through the expensive preparation of a plied.

More particularly the present invention relates to fibers based on a superchlorinated PVC / PVC mixture containing 17 to 20% PVC superchlorinated, strand strength ≤ 2.3 dtex, a residual shrinkage after oil treatment at 115 ° C for 30 min (ASTM Standard D 210 262 T) ≥ 6% and which are likely to be obtained by a process by which we spin, by a dry spinning process in a known manner, a solution of a mixture PVC / superchlorinated PVC at a rate of 17-20% of superchlorinated PVC in a mixture carbon sulfide / acetone solvent in a proportion of about 60/40 by volume, stretch the filaments in boiling water at a rate between 3 and 6 X, they are continuously stabilizes under voltage at a temperature between 125 and 140 ° C in the presence of steam under absolute pressure from 1.3 to 3.6 bar for 1 to 3 seconds, the cable thus obtained is mechanically or pneumatically curled in known manner, the crimp is continuously fixed at a temperature ≥ 100 ° C in presence of pressurized steam, the filaments then being retracted and dried in the usual way, continuously and cut in a known manner.

• un module d'élasticité ≥ 4 kN/mm², de préférence ≥ 5kN/mm²,
• un allongement à la rupture ≤ 36 %, de préférence ≤ 34 %,
• une ténacité à la rupture ≥ 21,5 cN/tex, de préférence ≥ 22 ou même plus.

Such sons also possess

• a modulus of elasticity ≥ 4 kN / mm ² , preferably ≥ 5kN / mm ² ,
• an elongation at break ≤ 36%, preferably ≤ 34%,
• a fracture toughness ≥ 21.5 cN / tex, preferably ≥ 22 or even more.

The present invention also relates to a method for obtaining fibers based on a mixture of polyvinyl chloride atactic and superchlorinated polyvinyl chloride, at a rate of 17 to 20% by weight of superchlorinated PVC, by dry spinning of a solution of the polymer mixture in a solvent mixture of carbon sulfide / acetone of about 60/40 by volume so known per se, drawing of the filaments in boiling water at a rate between 3 and 6 X, continuous stabilization of the filaments under voltage at a temperature between 125 and 140 ° C, preferably 130-135 ° C in the presence of water vapor at a pressure of 2.7 to 2.8 bar for 1 to 3 seconds, then mechanical or pneumatic crimping of the cable thus obtained in known manner and temperature fixing treatment > 100 ° C in the presence of pressurized steam, continuously, then shrinking in a known manner in boiling water or by any means suitable, then drying in a known manner continuously and cutting in the form fiber.

The present invention also relates to fiber yarns obtained from the fibers described above, having good tenacity, finer strands than those obtained up to and better textile workability, especially in weaving.

In particular, it is possible with the fibers according to the invention of obtaining fibers of metric number (NM) 50 (20 tex) which was not possible until then because the fiber titles PVC / superchlorinated PVC were too high to obtain fiber yarns sufficiently fine. For yarns of larger fibers, for example NM 20 (50 tex) it was possible to obtain yarns of fibers but their tenacity was insufficient. According to the invention, the yarns of fibers have a tenacity of at least 10 or 13 cN / tex which allows them to be woven at great speed.

The term “essentially atactic polyvinyl chloride” is intended to mean vinyl chloride homopolymer having a transition temperature second order generally between 65 and 85 ° C. Polychloride of vinyl consists predominantly of the isomeric form atactic, that is to say that it is a polymer whose atoms of chlorine and hydrogen are mostly randomly located on both sides of the chain constituting the skeleton of the molecule. Therefore, such poymer is normally of a non-crystallizable nature. Such a polymer is most commonly obtained in the least costly manner by known techniques of mass polymerization, suspension or emulsion temperatures generally above 0 ° C, more generally between 20 and 60 ° C or even more.

The superchlorinated polyvinyl chloride usable according to the present invention can be obtained for example by chlorination of a polyvinyl chloride suspension in the presence of actinic light, or by high temperature chlorination, or in the presence of radiation active chemicals; 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 thermal resistance never obtained until there, thanks to a selection of different elements. First the content of Superchlorinated PVC in the PVC / superchlorinated PVC mixture, between 17 and 20%, preferably 18 to 20%, associated with the use of the mixture solvent carbon sulfide / acetone in a proportion of 60/40 approximately achieves a better state of crystallinity of the mixture polymer. This state of crystallinity is further improved by the subsequent heat treatments, namely drawing in water boiling at temperatures between 85 and 100 ° C, at a rate between 3 and 6 X, preferably 3.5 - 5 X.

The drawing of the filaments according to the present invention is generally preceded by preheating, for example in water, to temperatures between 60 and 100 ° C, more generally between 75 and 85 ° C. One practical way is to use a heated water bath. Stretching itself can be done in 1 or 2 stages, but prefer to gradually increase the temperature of the filaments by preheating, pre-stretching for example in a bath whose water can be maintained between 70 and 95 ° C then continuous stretching at a temperature of one slightly higher than that of pre-stretching, preferably between 85 and 100 ° C or overall stretch indicated above. To be able to get a rate overall stretch of 6, it's easier to limit the stretch of filaments just after the die, by adjusting the speed of the rollers of recovery.

A second heat treatment that the filaments undergo contributes to fix the structure of the filaments and to give them their good properties, in particular shrinkage in oil at 115 ° C ≤ 6%, preferably at 5%, and allow strand titles to be obtained ≤ 2.3 dtex, preferably ≤ 2.25. Thanks to a better crystalline state, this treatment can be carried out at temperatures higher than those usually supported by PVC / superchlorinated PVC mixtures.

It is carried out in the presence of water vapor, under pressure of 1.3 to 3.6 bar, preferably 2.7 to 3 bar, at a temperature between 120 and 140 ° C, preferably 130 - 135 ° C for 1 to 3 seconds.

The filaments thus stabilized are crimped by any means known mechanical or pneumatic, for example by means of a nozzle such than that described in French patent n ° 83329 addition to FR n ° 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 shrunk and curled which allows better subsequent textile workability.

To become permanent, and facilitate the transition to carding by example, the crimp thus produced must be set at high temperature, generally between 110 and 120 ° C, in the presence of steam under pressure for at least 20 seconds, preferably at least 30 seconds, and preferably continuously.

One can use for example a device of known trade under the Towfix brand marketed by S.A. Serracant, which includes a closed rotary drum on which the filament cable is piled up curly, which are treated at the desired high temperature and continuous so that the process can be industrialized.

The permanently crimped filaments are then dried in the usual way, generally at a temperature in the region of 100 ° C.

The process according to the present invention can be carried out completely continuously since the stretching or even since the dissolution of the polymers until final threads or fibers are obtained. Thereby, it is easy to carry out industrially economically.

The polymers or solutions spun according to the present application may 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, dye affinity, thermal and light stability, electrical resistivity ...

Such a process leads to fibers with characteristics mechanical better than that of yarns based on polychloride mixtures vinyl / chlorinated polyvinyl chloride obtained according to the French patent 2,495,646.

In addition to thermal shrinkage and low titers, the values toughness at break, and elongation at break are improved which allows the production of much more efficient fiber yarns, improved wearability. They can also be used for production of knitwear, non-woven articles, alone or mixed with other fibers and can in particular undergo all treatments usual washing and dry cleaning under appropriate conditions.

Said yarns and fibers according to the invention are furthermore particularly appreciated in the textile sector because of certain properties inherent in the composition of mixtures: non-flammability, resistance to light, chemical inertness and power thermal, electrical and acoustic insulation.

The following examples, in which the parties are by weight, are given as an indication but not limiting.

EXAMPLE 1

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

• 80 % en poids de polychlorure de vinyle à prédominance atactique (indice AFNOR : 120 - selon la norme AFNOR T 51-013 - taux de chlore 56,5 %) et,
• 20 % de polychlorure de vinyle surchloré possédant un taux de chlore de 69 % et un indice AFNOR de 110.

The polymer consists of a mixture of:

• 80% by weight of polyvinyl chloride predominantly atactic (AFNOR index: 120 - according to AFNOR standard T 51-013 - chlorine level 56.5%) and,
• 20% superchlorinated polyvinyl chloride with a chlorine level of 69% and an AFNOR index of 110.

The solution thus obtained is filtered and, while being maintained at approximately 70 ° C., is spun through a die comprising 908 0.06 mm diameter holes in a dry spinning cell allowing the continuous recovery of the solvent mixture as described in French Patent No. 913,927. The filaments are then preheated in a water bath maintained at 80 ° C then stretched for the first times in a water bath maintained at 85 ° 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 in continuous under tension in a tube containing saturated steam at 125 ° C under a pressure of 2.32 bar, the inlet and outlet 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 retraction in a nozzle as described in the French patent n ° 83 329 addition to FR n ° 1 289 491 at 120 ° C in the presence of steam of water.

The filament cable is then steam treated in a device known commercially under the brand name Tow Fix from the Société Anonyme Serracant, continuously, at a temperature of 110 ° C. for 30 seconds, the cable being treated in a densified form. at a rate of 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 fiber results obtained are collated in Table 1 below.

Example 2

Example 1 is reproduced with the exception of the processing of fixing which is carried out under tension in the presence of water vapor at 130 ° C, under a pressure of 2.7 bars. Fiber characteristics 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., under a pressure of 3 bars. The characteristics of the fibers are listed in the table below; the tests corresponding to examples 1 to 3 were carried out compared to control fibers obtained according to French patent no. 2,495,642 from a PVC / superchlorinated PVC mixture at the rate of 17.5% of superchlorinated PVC in a sulphide mixture of carbon / acetone 50/50, spun and drawn 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, then crimped in a nozzle as shown in Example 1 and dried at 105 ° C. Example 1 Example 2 Example 3 Witness title to the strand 2.3 2.26 2.22 2.7 residual shrinkage 115 ° C in oil% 6 5.1 4.2 12 tenacity cN / tex 21.8 22.3 22.9 18 elongation% 36 34 31 65 Young's module kN / m2 5.2 5.35 5.41 2.8 shrinkage stress 10 ^-2 g / dtex 2.4 2.5 2.6 1.5 shrinking nozzle outlet% 4 3 2 2 final brewing% 15 13 11 11

The shrinkage stress which expresses the degree of orientation of the yarns is measured by means of a retractometer: the samples of filaments of length 4 cm, assembled in the form of test pieces with a titer of 400 dtex on average (each test being carried out on two test pieces) are subjected, after each of the different stages of stretching, stabilization and finally shrinking, to a temperature rise of 1 ° C per minute, from 30 ° C to 170 ° C. The retraction force expressed in 10 ^-2 g / dtex is measured on each test piece 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 which represents the molecular orientation characteristic of the products, which is designated by withdrawal constraint.

Embuvage (or crimp rate) determined on INSTRON 1122:

A fiber whose titer has been determined is subjected to a test until it reaches a fully relaxed state, (detection on the force / elongation curve).

On this curve, certain points are noted for the calculation of the following values: Embuvage% = Straightened length - Curled length Straightened length x 100

From the fibers obtained according to Example 2, yarns of fibers are prepared, the characteristics of which are as follows: the invention NM 20 witness the invention NM 50 witness Title (tex) 51.81 52.1 19.65 impossible to achieve NM 19.30 19.19 50.88 CV Uster% 9.57 12.19 15.10 - Imperfections over 1000m: - fine stitches 0 0 27 - - big dots 2 10 43 - - buttons 3 6 68 - breaking force (cN) 696 416.8 208.4 - CV breaking force 6.14 18.8 10.36 - Elongation at break % 26.7 29.3 21.25 - Fracture toughness cN / tex 13.4 8 11.43 -

Claims (8)

1. Cut fibres based on an atactic PVC/chlorinated PVC blend in a proportion of 17 to 20% of chlorinated PVC, characterised by the fact that they have a linear density ≤ 2.3 dtex and a residual shrinkage after treatment in oil at 115°C for 30 minutes according to the ASTM standard D 210262 T ≤ 6% and are obtainable by a process according to which a solution of a PVC/chlorinated PVC blend, in a proportion of 17-20% of chlorinated PVC, in a carbon sulphide/acetone solvent mixture in a proportion of approximately 60/40 by volume, is spun, by a process of dry spinning in a known manner, that the filaments are drawn in boiling water to a ratio of between 3 and 6X, that they are continuously stabilised under tension at a temperature of between 125 and 140°C in the presence of water vapour under absolute pressure of 1.3 to 3.6 bar for 1 to 3 seconds, that the tow thus obtained is crimped mechanically or pneumatically in a known manner, that the crimping is set continuously at a temperature ≥ 100°C in the presence of water vapour under pressure, the filaments being then relaxed and then dried conventionally, continuously, and cut in a known manner.
2. The cut fibres according to claim 1, characterised by the fact that they have an elongation at break ≤ 36%.
3. The cut fibres according to one of claims 1 or 2, characterised by the fact that they have a break tenacity ≥ 21.5 cN/tex.
4. The cut fibres according to one of claims 1 to 3, characterised by the fact that they have a modulus of elasticity ≥ 4 kN/mm².
5. A process for obtaining cut fibres according to one of claims 1 to 4, characterised by the fact that a solution of a PVC/chlorinated PVC blend, in a proportion of 17-20% of chlorinated PVC, in a carbon sulphide/acetone solvent mixture in a proportion of approximately 60/40 by volume, is spun, by a process of dry spinning in a known manner, that the filaments are drawn in boiling water to a ratio of between 3 and 6X, that they are continuously stabilised under tension at a temperature of between 125 and 140°C in the presence of water vapour under absolute pressure of 1.3 to 3.6 bar for 1 to 3 seconds, that the tow thus obtained is crimped mechanically or pneumatically in a known manner, that the crimping is set continuously at a temperature ≥ 100°C in the presence of water vapour under pressure, the filaments being then relaxed and then dried conventionally, continuously, and cut in a known manner.
6. The process according to claim 5, characterised by the fact that the filaments are stabilised under pressure at a temperature of between 130 and 135°C under an absolute pressure of between 2.7 and 3 bar.
7. The process according to one of claims 5 to 6, characterised by the fact that the crimping is set at a temperature of between 110 and 125°C.
8. Fibre threads based on fibres as defined in any one of claims 1 to 4, having a metric number ≥ 20 and a break tenacity ≥ 10 cN/tex.