EP0488907A1 - Fibres of polyvinyl chloride reticulated with diisocyanates and process for their preparation - Google Patents

Abstract

Yarns based on crosslinked PVC and process for obtaining them. Filaments, fibres and yarns based on crosslinked PVC comprise crosslinking bridges of formula I: <IMAGE> in which R is an aliphatic, cycloaliphatic or aromatic residue, R' an aliphatic or cycloaliphatic residue containing at least one CO and/or CN bond allowing it to be bonded to the polymer chain, such as an alkyl acrylate or methacrylate residue (alkyl = ethyl, propyl, butyl) or an aminoalkyl residue [alkyl = di(ethyl), di(propyl), di(butyl)] or R' is zero; they have an insolubles content of between 28 and 100 % and a degree of shrinkage in oil at 115 DEG C for 30 min according to ASTM Standard D 210262 T </= 8 %. They are obtained by dry spinning a processable solution of hydroxylated PVC containing 0.035 to 0.1 mol OH per 100 g of polymer and 7 to 20 %, relative to the mass of polymer, of a diisocyanate-oxime reaction product, in an acetone/carbon sulphide solvent mixture, drawing the filaments to a ratio of 3 to 6x, and then heat-treating at a temperature of between 120 and 145 DEG C for 2 to 10 min, under stress, to remove the oxime and to crosslink the polymer chains, and then relaxing in an aqueous fluid frame at a temperature of at least 98 DEG C. The yarns obtained have a thermal behaviour which is greatly improved in relation to the ordinary PVC yarns.

Description

The present invention relates to yarns based on polyvinyl chloride crosslinked by diisocyanate groups and to the process for obtaining them.
Polyvinyl chloride fibers are appreciated in the textile field because of certain special properties: non-flammability, resistance to light, chemical inertness and thermal, electrical and acoustic insulation power. Unfortunately, ordinary polyvinyl chloride prepared by the most commonly used process (at temperatures in the range of 0 to 80 ° C) because the least expensive is a predominantly atactically substantially non-crystallizable polymer with a transition temperature vitreous (Tg) of the order of 80-85 ° C; the yarns and fibers obtained from this polymer have, before retraction, sufficient mechanical qualities for their textile transformation, (toughness of 1.60 to 2.20 cN / dtex - elongation 25-35% - module 4-5 kN / mm²) but the finished articles have a too high withdrawal rate (up to 60%). If they are subjected to a shrinkage treatment, these yarns and fibers then have insufficient mechanical qualities for certain textile applications (tenacity 0.98-1.32 cN / dtex - elongation 100-130% - module 1.20 kN / mm² at 1.8 kN / mm²).
In order to improve the properties of fibers based on polyvinyl chloride, new polymers have been developed from vinyl chloride by a technique based on a polymerization carried out at temperatures below 0 ° C and descending down to - 60 ° C or even lower, in the presence of suitable catalysts, effective at these low temperatures.
These new polymers with a more syndiotactic structure have a glass transition temperature (Tg) generally greater than 90 ° -100 ° C. giving the yarns and fibers obtained better thermal resistance and markedly improved properties compared to textile products obtained from polyvinyl chloride. ordinary.

French application No. 2,161,084 published on 6.07.1973 illustrates fibers with good mechanical properties based on this type of polymer. However, such a low temperature polymerization process is an extremely expensive process which considerably increases the cost price of the fibers and takes away much interest from their industrial production.
It has also been proposed, according to French Patent No. 1,359,178 to improve fibers and yarns based on polyvinyl chloride (PVC) by mixing ordinary polyvinyl chloride with superchlorinated polyvinyl chloride. This solution which effectively makes it possible to obtain yarns and fibers with better mechanical characteristics is a solution which is all the more expensive industrially, the greater the proportion of superchlorinated polyvinyl chloride added.
Various other more or less complicated improvements have been tested: for example French patent No. 2,495,645 describes the production of yarns based on atactic PVC having improved properties, such as a residual shrinkage rate in boiling water. of the order of 1.5 to 35% and an elongation at break of the order of 75 to 80%. However, such wires still have insufficient thermal resistance.

Furthermore, French Patent No. 2 609 479 proposes obtaining articles based on chlorofibers made of PVC slightly crosslinked on the surface which do not shrink much and retain their fire behavior property. However, such articles have a yellow to brown coloration on the finished article and lose some of their flexibility due to the various treatments undergone. These latter phenomena strongly limit their textile use.

The present invention relates to crosslinked polyvinyl chloride (PVC) filaments, threads, fibers retaining their flexibility and a very light color and having limited shrinkage at temperatures equal to or greater than 100 ° C.

dans laquelle R est un reste aliphatique, cycloaliphatique ou aromatique, R′ un reste aliphatique ou cycloaliphatique comportant au moins une liaison C-O et/ou C-N permettant de le relier à la chaîne polymère tel qu'un reste d'acrylate ou méthacrylate d'alkyle (alkyle = éthyle, propyle ou butyle) ou un reste aminoalkyle alkyle = di(éthyle), di(propyle), di(butyle) ou R′ est nul

• possédant un taux d'insolubles compris entre 28 et 100 %, de préférence entre 70 et 100 %
• présentant un taux de retrait résiduel dans l'huile à 115°C pendant 30 mn, mesuré selon la norme ASTMD 210262 T ≦ 8 % de préférence ≦ 6 %.

More particularly, it relates to crosslinked PVC wires comprising crosslinking bridges of formula (1):

in which R is an aliphatic, cycloaliphatic or aromatic residue, R ′ an aliphatic or cycloaliphatic residue comprising at least one CO and / or CN bond allowing it to be linked to the polymer chain such as an acrylate or alkyl methacrylate residue (alkyl = ethyl, propyl or butyl) or an aminoalkyl residue alkyl = di (ethyl), di (propyl), di (butyl) or R ′ is zero

• having a rate of insolubles of between 28 and 100%, preferably between 70 and 100%
• having a residual shrinkage rate in oil at 115 ° C for 30 min, measured according to standard ASTMD 210262 T ≦ 8% preferably ≦ 6%.

• une résistance aux flux thermiques mise en évidence par la température du début d'écoulement ≧ 125°C, de préférence supérieure ou égale à 150°C.

La présente invention concerne également un procédé de filage à sec d'une solution conformable comprenant du polychlorure de vinyle hydroxylé, un produit de la réaction diisocyanate/oxime comportant un faible nombre d'atomes de carbone dans un mélange solvant acétone/sulfure de carbone, après mélangeage du système mélange solvant/PVC hydroxylé/diisocyanate-oxime, puis étirage en continu, à un taux compris entre 3 et 5 X à température comprise entre 60 et 100°C, les filaments étant ensuite soumis à un traitement thermique permettant l'élimination de l'oxime et la réticulation des chaînes polyméres par condensation des groupes isocyanates sur les groupes OH du PVC hydroxylé, dans une enceinte appropriée à une température de réticulation de 120° à 145°C, sous contrainte, la température de réticulation étant maintenue de 2 à 10 mn, de préférence environ 5 mn.The yarns and fibers according to the invention also have:

• a resistance to thermal fluxes evidenced by the temperature of the start of flow ≧ 125 ° C., preferably greater than or equal to 150 ° C.

The present invention also relates to a process for the dry spinning of a conformable solution comprising hydroxylated polyvinyl chloride, a product of the diisocyanate / oxime reaction comprising a small number of carbon atoms in an acetone / carbon sulphide solvent mixture, after mixing of the solvent mixture / hydroxylated PVC / diisocyanate-oxime system, then continuous drawing, at a rate of between 3 and 5 X at a temperature between 60 and 100 ° C, the filaments then being subjected to a heat treatment allowing the elimination of the oxime and the crosslinking of the polymer chains by condensation of the isocyanate groups on the OH groups of the hydroxylated PVC, in a suitable enclosure at a crosslinking temperature of 120 ° to 145 ° C., under stress, the crosslinking temperature being maintained 2 to 10 minutes, preferably about 5 minutes.

est une caractérisation du taux de réticulation jusqu'à 100 % d'insoluble. Lorsque le taux d'insoluble atteint 100 %, seul le taux de gonflement caractérise le produit réticulé. $$\text{Le taux de gonflement T . G =}\frac{\text{Volume THF + V polymère}}{\text{Volume polymère}}$$

cité ultérieurement, donne une indication de la densité des noeuds de réticulation, c'est-à-dire une image de la maille du réseau.

• _ Volume THF est mesuré à partir de la détermination de la masse du polymère gonflé - masse polymère sec.
• _ Volume polymère = $$\frac{\text{poids polymère sec}}{\text{densité polymère sec}}$$
  

The wires are then retracted in an aqueous fluid medium at a temperature equal to or greater than 98 ° C.
Optionally, a vapor stabilization phase for 1 to 3 seconds, under voltage, at a temperature between 105 and 130 ° C, can be carried out before the crosslinking phase. The wires can be shrunk in boiling water or in a nozzle supplied with pressurized steam. The threads are generally cut in the form of fibers; the fibers thus obtained have crosslinking bridges of formula (1), and therefore have a significant crosslinking evaluated by measuring the rate of insoluble matter: 28 to 100%, preferably 70 to 100%. This measurement is carried out as follows:
a sample is left for 48 hours at room temperature in tetrahydrofuran (THF). The solution is then filtered. The insoluble part swollen with THF is collected and weighed, then dried and weighed again. The difference in weighing allows the determination of the swelling rate (T. G). The soluble part is reprecipitated with methanol, dried and weighed. The insoluble mass (I) is brought back to the initial mass of the sample. $$\text{The insoluble level I =}\frac{\text{Insoluble mass}}{\text{Initial mass of the <figure-callout id="100" label="sample x" filenames="imgf0001.png,imgf0002.png" state="{{state}}">sample </figure-callout>}}\text{x}\text{100}$$

is a characterization of the crosslinking rate up to 100% insoluble. When the insoluble level reaches 100%, only the swelling rate characterizes the crosslinked product. $$\text{The rate of swelling T. G =}\frac{\text{THF + V polymer volume}}{\text{Polymer volume}}$$

cited later, gives an indication of the density of the crosslinking nodes, that is to say an image of the mesh of the network.

• _ THF volume is measured from the determination of the mass of the swollen polymer - dry polymer mass.
• _ Polymer volume = $$\frac{\text{dry polymer weight}}{\text{dry polymer density}}$$
  

The swelling rate of the crosslinked fibers is less than 25 and more generally between 6 and 15. The lowest values of the swelling rate correspond to the highest values of crosslinking density.

Les fils et fibres selon l'invention possèdent des caractéristiques de retrait résiduel tout à fait remarquables : ≦ 8 %, de préférence ≦ 6%.
La mesure de retrait à 130°C dans l'air a été réalisée dans un four cylindrique, avec montée en température de 2°C/mn. L'échantillon, de longueur initiale (1₀) environ 30 cm, est placé dans un four horizontal, une extrémité est maintenue fixe, l'autre mobile avec à son extrémité une masselotte en plomb. Le déplacement ( 1) est directement lu sur une réglette et retranscrit en pourcentage de retrait : R = ( 1/1₀)100. La masselotte de plomb, nécessaire au positionnement de l'échantillon, est considérée comme négligeable (0,1 mg/dtex) et le retrait enregistré, est assimilé à un retrait libre. On fait subir un recuit préalable, à 200°C, au fil nylon maintenant la masselotte de plomb, afin de s'affranchir de tout phénomène de retrait parasite. Dans ces conditions, on trace les courbes de retrait % en fonction de la température pour le témoin et les fils réticulés. A partir de ces courbes, on en déduit le retrait à 130°C.The crosslinking nodes are distributed regularly, which results in better regularity of the threads and therefore better subsequent properties, in particular shrinkage. The measurement of shrinkage consists in determining the variation in length of a test piece of the wire under standard pretension, after treatment in oil for 30 min at 115 ° C. according to standard ASTM D 210 262 T. $$\text{Withdrawal\% =}\frac{\text{Initial length - Length after heat treatment}}{\text{Initial length}}\text{x 100}$$

The yarns and fibers according to the invention have quite remarkable residual shrinkage characteristics: ≦ 8%, preferably ≦ 6%.
The shrinkage measurement at 130 ° C in air was carried out in a cylindrical oven, with a temperature rise of 2 ° C / min. The sample, of initial length (1₀) about 30 cm, is placed in a horizontal oven, one end is kept fixed, the other mobile with a lead weight at its end. The displacement (1) is directly read on a strip and transcribed in percentage of withdrawal: R = (1 / 1₀) 100. The lead weight, necessary for positioning the sample, is considered to be negligible (0.1 mg / dtex) and the recorded withdrawal is assimilated to a free withdrawal. The nylon wire holding the lead weight is subjected to prior annealing, at 200 ° C., in order to overcome any phenomenon of parasitic shrinkage. Under these conditions, the shrinkage curves% are plotted as a function of the temperature for the control and the crosslinked wires. From these curves, the shrinkage at 130 ° C. is deduced therefrom.

They also have a threshold temperature ≧ 125 ° C, preferably ≧ 150 ° C, an elongation at break ≦ 60%, preferably ≦ 40%, elongation which is all the lower as the rate of crosslinking is higher. Likewise, the higher the crosslinking rate, the better the thermal resistance of the wires and therefore all of their properties at high temperatures: decrease in shrinkage and shrinkage force before the flow zone, and decrease in temperature. flow threshold at temperatures ≧ 125 ° C.
Figure 1 shows the shrinkage of the crosslinked fibers with temperature. Curve No. 1 represents commercial chlorofiber (homopolymer PVC). It is observed that the shrinkage increases rapidly to 130 ° C. and then less rapidly to a ceiling value of the order of 160-170 ° C.
In this area a flow process occurs which quickly leads to the breaking of the spun yarns around 175-180 ° C. The behavior of the crosslinked fibers is completely different. Curves 2, 3, 4 (corresponding to Examples 2, 4, 5) are displaced towards high temperatures and the shrinkage value is clearly lower in all points. It is all the weaker as the fiber is more crosslinked based on the values of the swelling rates.
Even at temperatures of 200 ° C, the rupture is completely eliminated; thermal degradation then freezes the fibers into a rigid carbon structure.
As shrinkage is an almost instantaneous phenomenon, essentially governed by temperature, the variation in shrinkage expressed as a percentage has been studied for a unitary variation in temperature, ie 1 ° C.

(% / C°) est appelée retrait spécifique.
Le retrait spécifique en fonction de la température est représenté sur la figure 2. Les courbes représentent en fait la dérivée par rapport à la température des courbes montrées sur la figure 1.The height $$\frac{\text{dR}}{\text{dT}}$$

(% / C °) is called specific shrinkage.
The specific shrinkage as a function of the temperature is represented in FIG. 2. The curves in fact represent the derivative with respect to the temperature of the curves shown in FIG. 1.

• jusqu'à TS, on observe un retrait pur correspondant à un comportement élastoplastique du polymère
• au delà de TS, retrait et écoulement sont concomitants, le polymère a un comportement viscoplastique ; la déformation du matériau ne peut plus être compensée.

Sur la figure 2, les courbes 1, 2, 3, 4 représentent les mêmes produits que ceux indiqués sur la figure 1. Sur ces courbes, on peut lire directement les valeurs de température du seuil d'écoulement telle que définie ci-dessus.
Les fils et fibres du PVC connus jusque là cassent à des températures de l'ordre de 170 ou 180°C alors que les fils selon l'invention conservent leur structure à ces températures, ceci jusqu'à 225 ou 250°C.
Au delà, il se forme une structure carbonée protectrice évitant que les fils ne fuient devant la flamme. Cette caractéristique particulière est très intéressante pour toutes les applications textiles nécessitant une bonne résistance à l'exposition prolongée à de forts flux thermiques.
Contrairement aux articles textiles obtenus selon le brevet français N° 2 609 419, les articles textiles tels que tricots ou tissus obtenus à partir des fils et fibres de la présente invention restent souples et gardent une couleur claire. Cela permet leur teinture dans toutes les teintes selon les procédés habituels de teinture des chlorofibres.According to this figure, the specific shrinkage increases with temperature up to a maximum corresponding to the temperature at which a flow phenomenon appears which we will call throughout the text "temperature of the flow threshold" (TS).
In fact, there is competition between the pure withdrawal and the elongation of the fibers due to the flow:

• up to TS, there is a pure shrinkage corresponding to an elastoplastic behavior of the polymer
• beyond TS, shrinkage and flow are concomitant, the polymer has viscoplastic behavior; material deformation can no longer be compensated.

In FIG. 2, the curves 1, 2, 3, 4 represent the same products as those indicated in FIG. 1. On these curves, one can directly read the temperature values of the flow threshold as defined above.
The PVC yarns and fibers known hitherto break at temperatures of the order of 170 or 180 ° C. while the yarns according to the invention retain their structure at these temperatures, this up to 225 or 250 ° C.
Beyond, a protective carbon structure is formed, preventing the wires from leaking in front of the flame. This particular characteristic is very interesting for all textile applications requiring good resistance to prolonged exposure to strong thermal fluxes.
Unlike the textile articles obtained according to French patent No. 2 609 419, the textile articles such as knits or fabrics obtained from the yarns and fibers of the present invention remain flexible and keep a clear color. This allows them to be dyed in all shades according to the usual methods for dyeing chlorofibres.

The yarns and fibers according to the invention are prepared from a solution of hydroxylated PVC in the presence of a diisocyanate / oxime reaction product in a usual solvent mixture.

• les copolymères de chlorure de vinyle avec au moins un comonomère vinylique comportant des groupes OH tels que les acrylates ou méthacrylates d'hydroxyalkyle par exemple d'hydroxyéthyle, d'hydroxypropyle, d'hydroxybutyle, ou des copolymères chlorure de vinyle/acétate de vinyle partiellement hydrolysés.
• les polymères greffés obtenus par substitution nucléophile d'atomes de chlore par un greffon porteur d'au moins un groupe OH tel que les polymères obtenus selon la demande française N° 89/17359 déposée le 28.12.89
• les mélanges d'homopolymère du PVC atactique avec un copolymère ou polymère greffé contenant des groupes OH.

Tout au long de la description, on appellera PVC OH, tous les types de PVC, polymères greffés, copolymères ou mélanges contenant 0,035 à 0,1 mole de groupe OH/100 g de polymère tel que défini ci-dessus. Les solutions de PVC OH utilisables pour le filage à sec contiennent de 28 à 35 % environ de polymère dans un mélange solvant habituel sulfure de carbone/acétone, généralement en proportion 50/50 en volume. Pour les teneurs les plus élevées en unités OH, il est préférable d'utiliser des concentrations de 30 % ou plus.
Outre le PVC OH, la solution de sulfure de carbone/acétone contient le produit de réaction d'un diisocyanate sur un oxime.By hydroxylated PVC is meant a polymer containing 0.035 to 0.1 mole of OH groups per 100 g of hydroxylated polymer, in particular:

• vinyl chloride copolymers with at least one vinyl comonomer comprising OH groups such as hydroxyalkyl acrylates or methacrylates, for example hydroxyethyl, hydroxypropyl, hydroxybutyl, or vinyl chloride / vinyl acetate copolymers hydrolyzed.
• grafted polymers obtained by nucleophilic substitution of chlorine atoms with a graft carrying at least one OH group such as the polymers obtained according to French application N ° 89/17359 filed on 28.12.89
• mixtures of atactic PVC homopolymer with a graft copolymer or polymer containing OH groups.

Throughout the description, PVC OH, all types of PVC, graft polymers, copolymers or mixtures containing 0.035 to 0.1 mole of OH group / 100 g of polymer as defined above will be called. The PVC OH solutions which can be used for dry spinning contain approximately 28 to 35% of polymer in a usual solvent mixture of carbon disulphide / acetone, generally in a 50/50 proportion by volume. For the highest OH units, it is preferable to use concentrations of 30% or more.
In addition to PVC OH, the carbon sulfide / acetone solution contains the reaction product of a diisocyanate on an oxime.

The diisocyanate can be represented by the formula: OCN-R-NCO, R can be an aliphatic, cyclo aliphatic, aromatic group, which can carry other non-reactive functions with respect to isocyanates.
Among the diisocyanates which can be used, mention may be made of hexamethylene diisocyanate (HDI), but aromatic diisocyanates are preferred, for example diisocyanate 44 ′ diphenylmethane (MDI) and diisocyanate 44 ′ diphenylether (DIDE), phenylene diisocyanate (DPI).

The oximes which can be used are the acyclic ketoximes of formula: R₁ (R₂) C = N-OH in which R₁ and R₂ are aromatic or aliphatic groups having a low number of carbon atoms. Among the oximes which can be used, mention may be made of acetone and butanone oxime.

R, R₁, R₂ possédant les significations indiquées ci-dessus.The reaction product of diisocyanate and oxime is a compound (A) of formula:

R, R₁, R₂ having the meanings indicated above.

The reaction between the oxime and the diisocyanate is carried out separately at a temperature between room temperature and 80 ° C, preferably between 55 and 65 ° C and generally in the presence of catalysts based on transition metals such as the compounds of l tin and in particular tin dibutyldilaurate (DBDLE) although other catalysts can also be used, for a period of at least 2 hours, preferably 2 hours 30 to 3 hours, depending on the reactivity of the diisocyanate with respect to l blocking agent.
In the case where an aromatic diisocyanate is used, the presence of the catalyst is not essential.
Compound A is obtained in the presence of a suitable solvent such as toluene.
The diisocyanate / oxime system precipitates from the reaction medium and is then filtered, washed and dried. It can be checked by IR that the reaction is complete by disappearance of the characteristic band of the free -NCO groups. It is also necessary to ensure the purity of the system obtained.
In all cases (HDI, MDI, DIDE, PDI), a white powder is obtained which is soluble in the solvent mixture of carbon sulphide / acetone (50/50) which can be added directly to the solution of PVC OH in the solvent mixture.

The mixture-solvent system (acetone / CS₂), hydroxylated PVC and compound A (diisocyanate / oxime) are mixed for a variable period according to the spinning process to obtain a directly spinnable solution having a polymer concentration, included between 28 and 35%, preferably 30 to 35%.

For example, they can be mixed using a mixer at 30-35 ° C before being sent to the spinning cells.

They can also be mixed directly above the spinning cell using a known static mixer at a temperature between 70 and 120 ° C.

The solutions thus obtained are spun in the usual way by spinning in solution according to a dry method, either according to a usual method, that is to say with heating of the solution to approximately 80 ° C. or according to the overdissolved method with heating to about 120 ° C as described in French patent N ° 2524475.
The most commercially used solvents are benzene / acetone and preferably carbon sulfide / acetone mixtures in appropriate proportions, preferably 50/50 by volume.
Before spinning, the solutions are filtered to remove any solid type impurities or gels likely to clog the orifices of the die.
After spinning, the filaments are stretched to give them a molecular orientation and improve their mechanical characteristics at a rate between 3 and 6 X, in one or more stages at a temperature between 60 and 100 ° C, but preferably in the 'boiling water. It is generally preferred to gradually raise the temperature of the filaments, by preheating, pre-drawing in a bath, the water of which can be maintained between 75 and 95 ° C., then continuous drawing in boiling water to obtain an overall drawing rate of at least minus 4 X, preferably 4-6 X.

The filaments thus drawn are then subjected to stabilization under tension to limit shrinkage, for example in the presence of pressurized steam at a temperature between 105 and 130 ° C, preferably 110-120 ° C for 1 to 3 seconds.

After stabilization, the filaments are subjected, preferably continuously, to a free retraction which can be carried out in boiling water for a variable duration, for example at least 10 min in general 10-20 min or even more, in steam saturated water, for example by passing through a suitable nozzle (as described in the addition No. 83329 to French patent No. 1 289491).

The filaments must at any time after spinning be subjected to a treatment which causes the elimination of the blocking agent and the crosslinking of the fiber by condensation of the OH groups of the hydroxylated PVC on the diisocyanate groups.

To do this, the treatment is carried out batchwise or continuously, for example by passing through an appropriate enclosure such as an oven, at a crosslinking temperature of between 120 and 145 ° C., under stress, the crosslinking temperature being maintained at 2 min to 10 min depending on the diisocyanate and the oxime used. However, a duration of 4 to 5 minutes is generally sufficient. The duration of treatment depends on the temperature: the lower the temperature, the lower the temperature.

The crosslinking treatment is carried out before the retraction phase, that is to say directly after stretching or stabilization. The stabilization phase can also be included in the stress crosslinking phase.

Stabilization is then confused with crosslinking.
Cross-linking is characterized by the insolubility of the fibers or the rate of swelling in THF as explained above.

The filaments and fibers thus obtained have better thermal resistance than that of yarns based on ordinary polyvinyl chloride obtained hitherto. The process according to the invention makes it possible to obtain filaments at an attractive price capable of undergoing all the textile operations suitable for their finishing and of being used for the production of fabrics, knits, non-woven articles, etc. mixed with other yarns, which can undergo the usual washing and dry cleaning treatments under appropriate conditions without subsequent removal.
The polymers in solutions spun according to the present application may contain usual additives such as stabilizers, brighteners, pigments, dyes, plasticizers capable of improving some of their properties such as color, dye affinity, thermal stability, electrical resistivity, etc. in particular, they dye well with dispersed dyes.
The examples below illustrate the invention without limiting it.

Example 1 :

• d'abord l'acétone oxime (AO) en excès (160,6 g) en solution à 25 % dans le toluène anhydre,
• le catalyseur dibutyldilaurate d'étain (1 g environ),
• puis on ajoute goutte à goutte une solution de diisocyanato diphényle méthane (MDI) dans le même solvant (1 mole de MDI soit 250 g) (solution à 25 %).

La solution ainsi obtenue est chauffée jusqu'à 60°C et la température est maintenue pendant 2 H. On laisse refroidir en maintenant l'agitation.
On obtient environ 380 g d'un précipité blanc qui est filtré, lavé et séché et séparé du solvant.
On vérifie la pureté du produit ainsi obtenu par analyse élémentaire

• . par IR on constate l'absence de groupements isocyanates libres,
• . la température de déblocage, c'est-à-dire la température à partir de laquelle la réaction est reversible, déterminée par DSC et thermogravimétrie est de l'ordre de 100-120°C.

The following are introduced into a stirred reactor, previously purged with nitrogen:

• first excess acetone oxime (AO) (160.6 g) in 25% solution in anhydrous toluene,
• the tin dibutyldilaurate catalyst (approximately 1 g),
• then a solution of diisocyanato diphenyl methane (MDI) in the same solvent is added dropwise (1 mole of MDI or 250 g) (25% solution).

The solution thus obtained is heated to 60 ° C. and the temperature is maintained for 2 hours. The mixture is allowed to cool while maintaining stirring.
About 380 g of a white precipitate are obtained, which is filtered, washed and dried and separated from the solvent.
The purity of the product thus obtained is checked by elementary analysis.

• . by IR there is the absence of free isocyanate groups,
• . the unblocking temperature, that is to say the temperature from which the reaction is reversible, determined by DSC and thermogravimetry is of the order of 100-120 ° C.

84 g of product prepared above (MDI / AO) are introduced with 1200 g of hydroxylated PVC in 2800 g of solvent mixture CS₂ / acetone (50/50), 7.2 g of tin thioglycolate as stabilizer, the concentration of the solution being 30% polymer. The hydroxylated PVC consists of a vinyl chloride / hydroxyethyl acrylate copolymer (4.06% by weight), ie 0.035 mole OH per 100 g of polymer.
The solution is heated to 120 ° C. and then spun through a die comprising 80 holes of 0.06 mm diameter at a speed of 200 m / min. The filaments are then drawn in boiling water at different rates: 3 X, 4 X and then all stabilized under the same conditions at 110 ° C in the presence of vapor under tension for 2 seconds.
The crosslinking reaction is then carried out on the dry filaments, under stress at a temperature of 145 ° C for 5 min. They were then shrunk in boiling water for 20 min.

The table below indicates the title of the filaments as well as the toughness, elongation, shrinkage in oil at 115 ° C for 30 min, and at 130 ° C in air for various rates of drawing, this compared to yarns based on non-crosslinked atactic PVC obtained according to the process described in French patent N ° 2524475.

Example 2 :

• l'acétone oxime en excès (160,6 g) en solution à 25 % dans le toluène anhydre
• environ 1 g dibutyldilaurate d'étain comme catalyseur
• 168 g d'hexaméthylène diisocyanate (1 mole) ajoutés goutte à goutte.

The following are introduced into a stirred reactor, previously purged with nitrogen:

• acetone oxime in excess (160.6 g) in 25% solution in anhydrous toluene
• about 1 g tin dibutyldilaurate as catalyst
• 168 g of hexamethylene diisocyanate (1 mol) added dropwise.

The solution thus obtained is heated to 60 ° C. and maintained at this temperature for 4 hours.

A white precipitate is obtained which is filtered, washed and dried and then separated from the solvent.

• par IR, on constate l'absence de groupements isocyanates libres,
• par thermogravimétrie la température de déblocage a été déterminée à 100-120°C.

The purity of the product is checked by elementary analysis:

• by IR, there is the absence of free isocyanate groups,
• by thermogravimetry the release temperature was determined at 100-120 ° C.

84 g of the product prepared above are introduced with 1200 g of hydroxylated PVC, 2800 g of solvent mixture CS₂ / acetone (50/50), 7.2 g of tin thioglycolate as stabilizer, the concentration of the solution being 30% .
The hydroxylated PVC used is the same as that used in Example 1.

The solution is heated to 80 ° C., then spun through a die comprising 80 holes of 0.06 mm diameter, at a speed of 200 m / min.

The filaments are then drawn into boiling water at a rate of 4 X, then stabilized at 110 ° C in the presence of water vapor under tension for 2 seconds.
The crosslinking reaction is carried out on the dry fibers under stress, at a temperature of 145 ° C. for 5 min.
They are then retracted in boiling water for 20 minutes.
The filaments are then cut in the form of fibers.
The table below indicates the titer of the fibers as well as the toughness, elongation, shrinkage in boiling water and in oil at 115 ° C., this with respect to uncrosslinked PVC threads obtained according to French patent No. 2495645.

Example 3 :

A blocking agent is prepared from acetone oxime and MDI as indicated in Example 1 and its purity is checked. As indicated in example 1, 84 g of this same product are introduced with 1200 g of hydroxylated PVC identical to that used in example 1 in 2800 g of solvent mixture CS₂ / acetone (50/50) and 7.2 g of tin thioglycolate as stabilizer so as to obtain a polymer concentration of approximately 30%.
The solution is heated to 80 ° C. and then spun through a die comprising 80 holes of 0.06 mm diameter at a call speed of 200 m / min. The filaments are then drawn, stabilized, crosslinked, retracted as indicated in Example 1.

The table below indicates the title of the wires, the toughness, elongation and shrinkage in oil at 115 ° C for 30 min and at 130 ° C in air compared to control wires based on non-crosslinked atactic PVC. obtained according to French patent N ° 2494645.

Example 4

The MDI / AO reaction product is prepared as indicated in Example 1.
120 g of MDI / AO reaction product and 1200 g of hydroxylated PVC are introduced into 3086 g of solvent mixture CS2 / acetone (50/50 by volume), 7.2 g of tin thioglycolate as stabilizer, the concentration of the solution thus obtained being approximately 28% of hydroxylated PVC. This is a vinyl chloride / hydroxyethyl acrylate copolymer containing 0.05 mole OH per 100 g of polymer (11.6% by weight of acrylate).
The solution is then heated to 80 ° C. and then spun through a die comprising 80 holes of diameter 0.06 mm in diameter at a speed of 200 m / min.
The filaments are then drawn into boiling water at a rate of 4 X and then crosslinked under stress at a temperature of 145 ° C for 5 min, stabilization takes place during the crosslinking treatment.
The filaments are then retracted in boiling water for 20 minutes and then cut.
The table below indicates the values of tenacity, elongation, shrinkage at 115 ° C, 130 ° C as well as the insoluble and swelling rates.
The control wire is obtained according to the method of French patent N ° 2499648 from atactic PVC having undergone a stress stabilization steam treatment at a temperature of 120 ° C for 2 seconds.

Example 5

Example 4 is repeated but using a PVC containing 0.1 mole of OH per 100 g of polymer and using 240 g of the reaction product MDI / AO with 1200 g of hydroxylated PVC and 2230 g of solvent CS2 / acetone (50/50 by volume) and 7.2 g of tin thioglycolate. The concentration of the solution is approximately 35%.
The solution is spun and the threads treated as indicated in Example 4.
The yarns obtained have the following characteristics:

Example 6

A blocking agent is prepared from acetone oxime and MDI as indicated in Example 1 and its purity is checked. 84 g of the reaction product MDI / AO are introduced with 1200 g of a mixture of atactic PVC polymer and PVC OH in a proportion of 70/30 in 3086 g of solvent mixture CS2 / acetone (50/50 by volume), 7, 2 g of tin thioglycolate as stabilizer, the concentration of the solution being 28%.

The PVC OH used contains, alone, 0.15 mol OH / 100 g so that the PVC / PVCOH mixture contains 0.050 mol OH per 100 g of polymer mixture.
The solution of the polymer obtained is heated to 80 ° C. and then spun through a die comprising 80 holes of 0.06 mm diameter at a speed of 200 m / min. The filaments are then drawn into boiling water at a rate of 4 X. The dry fibers are then crosslinked under stress at temperature 145 ° C for 5 min.
Cross-linking treatment takes the place of stabilization.
Free retraction in boiling water is carried out on crosslinked wires for 20 min. The threads are then cut in the usual way.
The characteristics of the wires relative to control wires based on atactic PVC obtained according to French patent No. 2499648 having undergone a steam stabilization treatment at 120 ° C. for 2 seconds, are given in the table below:

Example 7

Example 6 is repeated, but using a polymer mixture containing 40% PVCOH with an OH content of 0.15 mol / 100 g so as to obtain a polymer mixture containing: 0.060 mol OH / 100 g of the polymer mixture.
The polymer solutions are obtained using 144 g of the reaction product MDI / acetone-oxime, 1200 g of polymer in 3086 g of solvent mixture in the presence of 7.2 g of tin thioglycolate at polymer concentration is 28% .

The yarns obtained were spun and treated as indicated in example 8. Their characteristics are gathered in the table below:

Example 8

• l'acétone oxime (160,6 g) en solution à 25 dans le toluène anhydre
• environ 1 g de dibutyldilaurate d'étain comme catalyseur
• 252 g de diphényléther 44′ diisocyanate (1 mole) ajoutés goutte à goutte.

La solution ainsi obtenue est chauffée jusqu'à 60°C et maintenue à cette température pendant 4 H.
On obtient un précipité blanc qui est filtré, lavé et séché puis séparé du solvant.
La pureté du produit est vérifiée par analyse élémentaire,

• par IR, on constate l'absence de groupements isocyanates libres
• la température de déblocage déterminée par thermogravimétrie, s'étale entre 80-120°C.

On introduit 84 g du produit préparé précédemment avec 1200 g de PVC hydroxylé, 2800 g de mélange solvant CS₂/acétone (50/50), 7,2 g de thioglycolate d'étain comme stabilisant, la concentration de la solution étant de 30 %.
Le PVC hydroxylé utilisé est le même que celui indiqué dans l'exemple 1.The following are introduced into a stirred reactor, previously purged with nitrogen:

• acetone oxime (160.6 g) in solution at 25 in anhydrous toluene
• about 1 g of tin dibutyldilaurate as catalyst
• 252 g of diphenyl ether 44 ′ diisocyanate (1 mole) added dropwise.

The solution thus obtained is heated to 60 ° C. and maintained at this temperature for 4 hours.
A white precipitate is obtained which is filtered, washed and dried and then separated from the solvent.
The purity of the product is verified by elementary analysis,

• by IR, there is the absence of free isocyanate groups
• the release temperature determined by thermogravimetry ranges between 80-120 ° C.

84 g of the product prepared above are introduced with 1200 g of hydroxylated PVC, 2800 g of solvent mixture CS₂ / acetone (50/50), 7.2 g of tin thioglycolate as stabilizer, the concentration of the solution being 30% .
The hydroxylated PVC used is the same as that indicated in Example 1.

The solution is heated to 80 ° C., then spun through a die having 80 holes of 0.06 mm diameter at a speed of 200 m / min.

The filaments obtained are then drawn into boiling water at a rate of 4 X then crosslinked under stress at 140 ° C for 10 min, and retracted for 20 min in boiling water, the characteristics of the fibers obtained are as follows:

Claims (13)

1) Filaments, fibers, yarns based on crosslinked PVC comprising crosslinking bridges of formula I:

in which R is an aliphatic, cycloaliphatic or aromatic residue, R ′ an aliphatic or cycloaliphatic residue comprising at least one CO and / or CN bond making it possible to link it to the polymer chain such as a residue of alkyl acrylate or methacrylate ( alkyl = ethyl, propyl, butyl) or an aminoalkyl residue [alkyl = di (ethyl), di (propyl), di (butyl)] or R ′ is zero - with a rate of insolubles of between 28 and 100% and - an oil shrinkage rate at 115 ° C for 30 minutes according to ASTM D 210262 T ≦ 8%. 2) Filaments, threads, fibers according to claim 1, characterized in that the swelling rate is less than 25. 3) Filaments, threads, fibers according to claim 1 characterized in that the rate of insolubles is between 70 and 100%. 4) Filaments, threads, fibers according to claim 1 characterized in that the shrinkage rate at 115 ° C in the oil is ≦ 6% 5) Filaments, threads, fibers according to claim 1 characterized in that the start of the flow temperature is ≧ 125 ° C 6) Filaments, threads, fibers according to claim 1 characterized in that the rate of shrinkage in air at 130 ° C is ≦ 15%. 7) Process for the dry spinning of a conformable solution comprising hydroxylated polyvinyl chloride (PVC) containing 0.035 to 0.1 mole OH per 100 g of polymer and 7 - 20% relative to the mass of polymer of a product of the diisocyanate / oxime reaction of formula:

with R₁ and R₂ aliphatic groups containing a small number of carbon atoms, R aliphatic, cycloaliphatic or aromatic group, in an acetone / carbon sulphide solvent mixture, after mixing the solvent / hydroxylated PVC / diisocyanate-oxime system, then drawing filaments at a total rate between 3 and 6 X at a temperature between 60 and 100 ° C, the filaments then being subjected to a heat treatment at a temperature between 120 and 145 ° C, for 2 to 10 minutes, under stress , allowing the elimination of the oxime and the crosslinking of the polymer chains by condensation of the isocyanate groups on the OH groups of the hydroxylated PVC, in an appropriate enclosure, then to a retraction in an aqueous fluid medium at a temperature of at least 98 ° C. . 8) Method according to claim 7 characterized in that the PVC OH contains 0.035 to 0.1 mole of OH per 100 g of polymer. 9) Method according to claim 7 characterized in that the oxime used is acetone oxime. 10) Process according to claim 7 characterized in that the diisocyanate has the formula OCN-R-NCO with R = aliphatic, cycloaliphatic, aromatic group. 11) Method according to claim 7 characterized in that the stretch rate is 4 X. 12) Method according to claim 7, characterized in that before crosslinking, the filaments are stabilized under tension in the presence of steam at a temperature between 105 and 130 ° C, for 1 to 3 seconds. 13) Method according to claims 7 and 11, characterized in that the stabilization phase is merged with the crosslinking phase.

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