EP0122836B1 - Method for the preparation of phenoplast fibres - Google Patents

Method for the preparation of phenoplast fibres Download PDF

Info

Publication number
EP0122836B1
EP0122836B1 EP84400583A EP84400583A EP0122836B1 EP 0122836 B1 EP0122836 B1 EP 0122836B1 EP 84400583 A EP84400583 A EP 84400583A EP 84400583 A EP84400583 A EP 84400583A EP 0122836 B1 EP0122836 B1 EP 0122836B1
Authority
EP
European Patent Office
Prior art keywords
fibres
fibers
composition
temperature
die
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84400583A
Other languages
German (de)
French (fr)
Other versions
EP0122836A1 (en
Inventor
Jacques Seignan
Bernard Kafka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Isover SA France
Original Assignee
Saint Gobain Isover SA France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saint Gobain Isover SA France filed Critical Saint Gobain Isover SA France
Publication of EP0122836A1 publication Critical patent/EP0122836A1/en
Application granted granted Critical
Publication of EP0122836B1 publication Critical patent/EP0122836B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/18—Formation of filaments, threads, or the like by means of rotating spinnerets
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
    • D01F6/76—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from other polycondensation products

Definitions

  • the invention relates to a process for the production of fibers from phenoplast resins of the resol type.
  • Phenoplast resins are obtained by polycondensation of a phenol and an aldehyde. Most commonly phenoplasts come from the condensation of phenol and formalin. In the following description, we will mainly refer to these phenol resins based on phenol and formaldehyde, but the characteristics of the invention mean that it can be applied to all phenoplast resins provided that they have the properties which will be discussed below.
  • the novolaks are obtained by polycondensation of an excess of phenol relative to the amount of formalin used, in the presence of an acid catalyst.
  • the prepared resin which is hot melt, is crosslinkable using a crosslinking agent such as hexamethylene tetramine or paraformaldehyde in the presence of an acid catalyst. Cross-linking is accelerated by a rise in temperature.
  • the resols come from the polycondensation of an excess of formalin relative to the amount of phenol used, in the presence of a basic catalyst.
  • the formation of the resin which is accelerated when the temperature rises is difficult to control. It results in very diverse products according to the operating conditions and in particular according to the duration of the reaction. If the reaction is not stopped it continues until the formation of a solid product which is infusible and therefore cannot be spinned. To maintain the resin in conditions under which it can be worked, the reaction should be blocked by lowering the temperature and / or neutralizing the mixture. A resin in solution is then obtained, the characteristics of which, in particular of viscosity, vary according to the degree of progress of the reaction.
  • the resin is crosslinkable and crosslinking can be accelerated in the presence of an acid catalyst. The crosslinking is all the faster the higher the temperature.
  • novolak fibers are traditionally obtained by melting the hot-melt resin followed by fiberizing and treatment in an aqueous or gaseous medium with the crosslinking agent and the catalyst.
  • This treatment resulting in crosslinking is very long because of the need to diffuse the crosslinking agent and the catalyst in the solidified resin fiber. It can extend over several hours.
  • the operation leading to the formation of the fibers is particularly delicate. Unlike the novolaks for which the cooling after passage of the molten mixture in the die leads to fibers in a way frozen and well individualized, even if the crosslinking is barely started, the fibering operated with a resol in a state suitable for spinning, c that is to say a resol whose evolution has been stopped at a degree of condensation such that the viscosity is satisfactory, leads to the production of unstabilized fibers which remain sticky.
  • the invention proposes to provide a process for the production of fibers from resols.
  • the resin used the nature and the proportions of the products possibly added, in particular a crosslinking catalyst, are chosen to constitute a mixture whose characteristics, in particular of viscosity, are suitable for the formation of fibers by passage in a sector.
  • composition to be fiberized is immediately directed to a member acting as a die and which is consisting of a centrifuge.
  • the composition introduced into the centrifuge covers the inner peripheral wall of the centrifuge. This wall is pierced with orifices through which the composition passes. The latter is projected out of the orifices in the form of thin filaments which stretch into fibers and the orifices are of dimensions such that each of them gives rise to a separate fiber.
  • the conditions determining the maturation kinetics of the fibers formed, in particular the choice of the possible catalyst and of its proportions, and the temperature conditions of the surrounding atmosphere in which the fibers are projected, are chosen so that during their trajectory in this atmosphere until they are received, the fibers are sufficiently crosslinked and dried to keep a clean shape and do not stick to each other.
  • the preparation of resolated fibers is subject to conflicting requirements.
  • it may seem desirable to form a mixture capable of accelerating the evolution process and on the other hand when such a mixture is actually carried out, it is difficult to sufficiently control the evolution so as to maintain the mixing under conditions suitable for passing through a die and drawing the fibers.
  • compositions used according to the invention To be able to fiberize the compositions used according to the invention and taking into account the fact that they evolve rapidly towards a state in which precisely they could no longer be used for the formation of fibers, it is necessary to ensure that the mixture formed is very quickly used .
  • the mixture is therefore formed as it is used. Once the mixture has been formed, the means used to produce the fibers must retain this mixture for as short a time as possible.
  • the amount of composition held in the centrifuge can be extremely small. It can correspond to the quantity passing in a few seconds, so that the average residence time is very short and that there is no risk of "freezing" the composition before it passes through the orifices.
  • the fibers being projected out of the centrifuge they must be stabilized as quickly as possible.
  • the time interval separating the appearance of the fibers at the outlet of the centrifuge from their deposition on the collecting member is necessarily limited by the dimensions of the installation used.
  • the formation of these bubbles is not desirable.
  • the bubbles break the homogeneity of the structure of the fibers and in particular harm their mechanical properties.
  • the temperature of the fibers in the atmosphere surrounding the centrifuge is preferably kept below the boiling temperature of the water, or of the water / solvent mixture, present in the composition.
  • the temperature not to be exceeded corresponds approximately to that of boiling water.
  • the temperature of the fibers, at least in the region closest to the centrifuge does not exceed 80 ° C.
  • the temperature of the atmosphere itself can be significantly higher than that of the fibers as a result of the cooling caused on them by evaporation. We will see in the examples that the gas temperature can reach and even exceed 200 ° C.
  • the fibers are subjected to a temperature which increases when they move away from the centrifuge.
  • the exchanges taking place very quickly due to the fineness of the fibers, the crosslinking progressing and the drying taking place, it is possible to reach in the areas remote from the centrifuge temperatures higher than the limit temperatures indicated above. above.
  • the hot gas stream is preferably driven at a relatively low speed when it is directed transversely to the direction of projection of the fibers out of the centrifuge to avoid folding the fibers too early on each other when they are not yet perfectly stabilized.
  • the resin or resin-catalyst mixture should have a viscosity suitable for the mode of fiber formation envisaged.
  • a viscosity of the order of 500 to 30,000 mPas and preferably from 1,500 to 10,000 mPas is advantageously chosen.
  • the resin or the mixture is neither too fluid, which would lead to premature rupture of the filaments generating droplets and / or products that are insufficiently drawn, or too viscous, which would require the use of relatively large orifices and the fibers obtained would not meet the characteristics of fineness ordinarily sought.
  • the viscosity of the composition used is determined first of all by that of the resin, which itself depends on how the resin is prepared. It is thus necessary to take into consideration the reaction time and temperature, as well as the molar ratio of the formalin and the starting phenol. Condensation must be stopped when the viscosity suitable for spinning is reached.
  • the viscosity of the resin can however be modified by the addition of solvents.
  • the resin used preferably has a molecular mass of between 100 and 1000 and more particularly between 400 and 800.
  • the resin is preferably prepared from phenol and formaldehyde introduced in a molar ratio of formaldehyde to phenol of between 1.3 and 1.7.
  • a third solvent is advantageously used in as small a quantity as possible.
  • a compound which is both miscible with water and with resin and which is capable of being easily removed during the subsequent treatment of the fibers is used as a third solvent.
  • the third solvent is an alcohol, in particular methanol.
  • the viscosity of the assembly added to the resin can also be adjusted to avoid that, at the time of mixing, a too strong modification of the viscosity is observed.
  • thickening agents for example glycols, and preferably di- or triethylene glycol.
  • these thickening agents are introduced which, while allowing a higher final viscosity to be reached, also promote the homogenization of the mixture.
  • the crosslinking catalysts used are strong acids, mineral or organic, alone or as a mixture. Acids such as sulfuric acid, phosphoric acid or hydrochloric acid and their mixtures in aqueous solution are preferably used.
  • the use of a catalyst in solution allows a good dispersion thereof within the resin provided that the miscibility has been ensured as we have indicated above.
  • the dispersion of the catalyst in the resin is a determining factor for the way in which the crosslinking takes place. Good dispersion naturally favors rapid and homogeneous crosslinking, which is desirable under the conditions used according to the invention.
  • the characteristics of the spun compositions used according to the invention can be further modified to improve the formation and drawing of the fibers.
  • surfactant it is also usual in the processes of formation of fibers from synthetic resins to add small proportions of a surfactant, always to improve the characteristics during fiberizing, and in particular to avoid early hair breaks.
  • these are nonionic surfactants, such as sorbitan or cationic fatty alcohols, which exhibit better stability in an acid medium.
  • Preferred surfactants are those sold under the names “TWEEN” and “SPAN” (registered trademarks). They are introduced into the composition in an amount of 0.5 to 3% by weight.
  • FIG. 1 The installation shown diagrammatically in FIG. 1 is particularly representative of those which can be used according to the invention. It performs the conditioning of the composition, the fiberizing of this composition and the stabilization of the fibers formed.
  • the resin previously prepared and optionally containing the various fiberizing additives is placed in a tank 1 in which it is maintained at a temperature which allows its conservation.
  • the resin in the liquid state taken from the tank 1 by means appropriate to its state: pump, screw, etc. is conducted in a determined quantity in a mixer 2.
  • the mixer also optionally receives in metered quantities the catalyst originating from 'a tank as shown in 24.
  • the mixing operation is very vigorous to obtain a composition that is as homogeneous as possible.
  • the volume offered in the mixer is small so that the composition stays there as short as possible.
  • the composition is then sent directly to the centrifuge device.
  • the line 8 leading the composition to be fiberized in the centrifuge device is as short as possible.
  • the mixer 2 is advantageously located near the centrifuge device.
  • the device comprises a centrifuge 3 fixed on a shaft 4 which is rotated by an electric motor 5 by means of belts 6.
  • the shaft 4 is mounted on bearings 7.
  • the shaft 4 is hollow.
  • Line 8 leading the composition to the centrifuge is housed in this tree.
  • the centrifuge device itself comprises a basket 9 on the bottom of which the composition is poured.
  • the basket is pierced on its peripheral wall 10 with regularly spaced holes 11.
  • the composition reaches the inner face of the wall 10 and escapes through the orifices 11 in the form of large composition nets, which are projected onto the peripheral wall 12 of the centrifuge proper 3.
  • the presence of the basket 9 allows a first equalization of the distribution of the composition on the inner peripheral wall of the centrifuge.
  • the use of a basket is all the more advantageous when the centrifuge is larger.
  • the "natural" distribution of the composition is more likely to be unbalanced. It is very important for the quality of the fibers to have at all points of the centrifuge the same "reserve", that is to say the same thickness of composition so that the centrifugation conditions are everywhere the same and therefore that the fibers are formed under the same conditions.
  • composition which forms the reserve escapes from the centrifuge through the orifices 14 arranged at the periphery.
  • the orifices 14 have dimensions such that each of them gives rise to a single fiber which is then projected into the surrounding atmosphere.
  • the internal profile of the centrifuge is determined so as to facilitate the flow of the composition.
  • the orifices are preceded by a part of triangular cross section 15 which leads the composition towards the orifices 14. This profile notably avoids the stagnation of composition in blind spots, stagnation which could lead to deposits of crosslinked resins.
  • FIG. 2 shows a centrifuge comprising a single row of orifices 14. It is of course possible to use a centrifuge comprising several rows of orifices, as shown in FIG. 3. In this case, it is necessary to choose the distance between two successive rows so that the fibers formed do not risk re-sticking before being stabilized. The distance between two orifices in the same row is also chosen so as to prevent the fibers from sticking together.
  • the profile of the centrifuge with several rows of orifices represented in FIG. 3 also includes grooves 26 on the internal face, the section of which decreases when approaching the orifices 14, which allow good circulation of the material to be fiberized to each row orifices.
  • the amount of composition in the basket and the centrifuge is kept at the minimum necessary to continuously feed the orifices 14.
  • the "reserve” must suitably cover the orifices 14. This reserve must however be small to shorten the residence time.
  • the composition is sprayed out of the centrifuge in the form of filaments, the dimensions of which are determined by those of the orifices.
  • the orifices ordinarily, taking into account the viscosities of the composition which have been indicated above and in order to obtain fine fibers of the order of 20 micrometers or less, the orifices have a diameter advantageously less than 1 mm and preferably between 0.2 and 0 , 8 mm. For larger diameters, and if the other conditions remain unchanged, the fibers produced are larger. To find finer fibers, it is then necessary to carry out a more violent centrifugation and / or to reduce the flow of composition per orifice.
  • the fibers are projected and stretch substantially in the plane perpendicular to the axis of rotation of the centrifuge. They develop in spirals which can extend at relatively large distances from the centrifuge when the initial acceleration is high.
  • the path of the fibers in the plane, which can reach a meter or more, is usually limited for reasons of the size of the receiving enclosure 19.
  • the path of the fibers is limited by blowing a gas stream along the walls 16, sufficiently intense to fold the fibers before they reach these walls.
  • the blowing can be carried out for example by means of a series of nozzles 18 disposed along a conduit 17 for supplying compressed air.
  • the nozzles 18 are preferably close enough to each other so that the jets fuse very quickly and constitute a practically continuous gas layer which obstructs the passage of the fibers.
  • the fibers from the start of their path towards the wall 16 of the receiving enclosure 19, are subjected to the heat treatment which makes it possible to substantially accelerate the kinetics of crosslinking of the mixture and promotes the elimination of water and / or solvents present in the fibers.
  • This heat treatment is advantageously obtained by means of hot gas streams arranged on the path of the fibers between the outlet of the centrifuge and the point where they are folded down.
  • the hot gaseous layers are directed on the path of the fibers with a speed and at a temperature such that the modification of the path can be limited as much as possible and, consequently, the risks of sticking of the fibers not yet stabilized.
  • the speed of the gases is preferably kept below 20 m / s.
  • Figure 1 shows a double supply of hot gases. These two supplies are made from chambers 20 and 21 arranged concentrically around the centrifuge.
  • the chambers 20 and 21 are supplied by one or more gas burners by means of pipes not shown. They are separated from the receiving enclosure 19 by widely open grids 22 letting the gases pass at low speed.
  • the installation shown comprises two hot gas emission chambers, it is of course possible to regulate the temperature of the gases of these two chambers independently of one another. It is also possible to provide a larger number of gas emission chambers to control even better the progress of the conditions for treating the fibers.
  • centrifuge may be advantageous to protect the centrifuge against heat coming from the neighboring chamber 20 by interposing for example a coil 25 surrounding the shaft 4 and the top of the centrifuge, and in which cooling water circulates .
  • the length of the path required before to gather the fibers is determined at the same time as the gas temperature conditions for each composition treated, it being understood that in all cases it is necessary to collect fibers sufficiently dried and crosslinked so that they do not risk sticking to each other.
  • the distance separating the centrifuge from the receiving belt is such that the time taken by the fibers to travel this path is between 0.1 and 2 s.
  • the fibers carried by the gases are deposited on a conveyor belt 23 where they constitute a felt of entangled fibers.
  • the suction means consist of a box 26 disposed under the conveyor and a fan, not shown.
  • the conditions set out above according to the invention make it possible to collect fibers in which the crosslinking process is very advanced and this in a very short time. If the complete residence time of the fibers in the receiving enclosure is very short, it may happen that the fibers have not reached a degree of maturation (or crosslinking) allowing them to be given the best possible properties. In this case, it is advantageous to complete the crosslinking by a very brief passage in an oven.
  • the temperature during such a heat treatment is greater than 100 ° C., and preferably between 100 and 150 ° C.
  • Example of fiber preparation in the presence of a catalyst Example of fiber preparation in the presence of a catalyst.
  • the reaction is stopped by cooling when the desired viscosity is reached. This is measured by the flow tube method.
  • the reaction is stopped by cooling to 25 ° C.
  • the resin obtained has a viscosity of 1000 mPas at 25 ° C.
  • the dry extract constitutes 70.5% of its mass.
  • the resin is stored at a temperature of 5 to 7 ° C.
  • the viscosity of the fiber premix is 13,000 mPas at 25 ° C.
  • the catalyst is measured at 7 parts.
  • the mixture used to form the fibers is, as the case may be, 100 parts by weight of resin premix for 5 to 10 parts of catalyst.
  • This mixture is in a homogeneous form with a viscosity varying from 3500 to 5000 mPas at 25 ° C.
  • the operation is carried out continuously in an enclosure with a square section, and with a height of approximately 2.5 m of the type shown in FIG. 1.
  • the mixture obtained in 4 is led by a pipe of the mixer in the receiving basket.
  • the centrifuge and the basket rotate at 3000 rpm.
  • the basket is pierced with 40 holes of 1.2 mm in diameter and the centrifuge whose diameter is 200 mm has 150 holes of 0.5 mm in diameter.
  • the fibers deploy in the air blown by 5 concentric chambers.
  • the speed of the gas emitted by these chambers increases as one moves away from the centrifuge, ensuring progressive deflection of the fibers.
  • the air is heated to a regulated temperature between 150 and 160 ° C.
  • a certain amount of air at room temperature is introduced through the walls forming the sides of the enclosure.
  • the air temperature is 80 ° C at the receiving conveyor.
  • the fibers are deposited in a continuous sheet of approximately 50 cm in width, formed of long dried and largely crosslinked fibers.
  • the regulation of the suction allows, by controlling the temperature at the bottom of the hood, to vary the degree of crosslinking.
  • the fiber diameters are between 2 and 19 ⁇ m.
  • the histogram of the diameters is of very tight Gaussian type with an average diameter of 7 micrometers.
  • the average tensile strength is around 300 MPa.
  • the density of the felt is approximately 20 kg / m 3 and its thermal conductivity on the order of 35 mW / m ° K for a thickness of 80 mm.
  • the felt obtained previously can be completely crosslinked by passing through the oven for 5 minutes at 120 ° C.
  • the felt which is not completely crosslinked has a certain thermoplasticity. This can be taken advantage of to constitute a self-bonding felt: For this purpose the felt obtained is subjected for 3 minutes to a temperature of the order of 220 ° C. by slightly compressing it.
  • a felt is thus obtained having a cohesion which makes it easy to handle.
  • the fibers are formed by rotating the system at 3800 rpm.
  • the basket 9 is pierced with 6 holes of 2.5 mm in diameter and the centrifuge has 4 rows of 150 holes of 0.4 mm in diameter.
  • a stabilized fiber flow rate is obtained which is greater than that obtained with a single row of orifices.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
  • Artificial Filaments (AREA)

Abstract

1. Method of forming fibres based on resins of the resol type resulting from the condensation of formol and phenols in a molar ratio of formol to phenol in excess of characterised in that the composition used for forming the fibres is brought to a situation where it can be cross-linked and its viscosity is adjusted immediately prior to its introduction into a die or spinneret, this preparation and adjustment being carried out continuously on a small quantity of composition, the composition thus prepared feeding a centrifugal die and passing through the orifices in this die, each orifice giving rise to one fibre projected into the atmosphere surrounding the die from which it is drawn, the constitution of the composition used and the conditions of temperature in the atmosphere surrounding the centrifugal die being chosen so that the fibres collected are sufficiently stabilised to retain a proper shape and not to stick to one another.

Description

L'invention est relative à un procédé de production de fibres à partir de résines phénoplastes de type résol.The invention relates to a process for the production of fibers from phenoplast resins of the resol type.

La formation de fibres à partir de résines phénoplastes est à l'heure actuelle une technique complexe qui comprend des étapes relativement longues et malaisées à mettre en oeuvre. Ces techniques sont cependant appliquées car elles permettent d'obtenir des produits dont les qualités, en particulier vis-à-vis de la résistance au feu, sont remarquables.The formation of fibers from phenoplast resins is at present a complex technique which includes relatively long and difficult steps to implement. These techniques are however applied because they make it possible to obtain products whose qualities, in particular with regard to fire resistance, are remarkable.

Les résines phénoplastes sont obtenues par polycondensation d'un phénol et d'un aldéhyde. Le plus couramment les phénoplastes proviennent de la condensation du phénol et du formol. Dans la suite de la description, nous nous référerons essentiellement à ces résines phénoplastes à base de phénol et formol, mais les caractéristiques de l'invention font que celle-ci peut s'appliquer à toutes les résines phénoplastes pour autant qu'elles présentent les propriétés dont il sera question plus loin.Phenoplast resins are obtained by polycondensation of a phenol and an aldehyde. Most commonly phenoplasts come from the condensation of phenol and formalin. In the following description, we will mainly refer to these phenol resins based on phenol and formaldehyde, but the characteristics of the invention mean that it can be applied to all phenoplast resins provided that they have the properties which will be discussed below.

Traditionnellement, on distingue deux types de résines phénoplastes qui sont désignés sous les noms génériques de "novolaques" et de "résols". Ces dénominations recouvrent des produits qui à la fois par leur mode de préparation, leur structure et certaines de leurs propriétés différent sensiblement.Traditionally, a distinction is made between two types of phenoplast resins which are designated under the generic names of "novolaks" and "resols". These names cover products which at the same time by their mode of preparation, their structure and some of their properties differ significantly.

De façon simplifiée les novolaques sont obtenues par polycondensation d'un excès de phénol par rapport à la quantité de formol utilisée, en présence d'un catalyseur acide. La résine préparée, qui est thermofusible, est réticulable à l'aide d'un agent de réticulation tel que l'hexaméthylène tétramine ou le paraformaldéhyde en présence d'un catalyseur acide. La réticulation est accélérée par une élévation de la température.In a simplified manner, the novolaks are obtained by polycondensation of an excess of phenol relative to the amount of formalin used, in the presence of an acid catalyst. The prepared resin, which is hot melt, is crosslinkable using a crosslinking agent such as hexamethylene tetramine or paraformaldehyde in the presence of an acid catalyst. Cross-linking is accelerated by a rise in temperature.

Toujours de façon simplifiée, les résols proviennent de la polycondensation d'un excès de formol par rapport à la quantité de phénol utilisée, en présence d'un catalyseur basique. La formation de la résine qui est accélérée lorsque la température s'élève est difficile à maîtriser. Elle aboutit à des produits très divers selon les conditions opératoires et notamment selon la durée de la réaction. Si la réaction n'est pas stoppée elle se poursuit jusqu'à la formation d'un produit solide qui est infusible et donc n'est pas filable. Pour maintenir la résine dans des conditions dans lesquelles elle peut être travaillée, il convient de bloquer la réaction par un abaissement de température et/ou neutralisation du mélange. On obtient alors une résine en solution dont les caractéristiques, notamment de viscosité, varient selon le degré d'avancement de la réaction. La résine est réticulable et la réticulation peut être accélérée en présence d'un catalyseur acide. La réticulation est d'autant plus rapide que la température est plus élevée.Still in a simplified manner, the resols come from the polycondensation of an excess of formalin relative to the amount of phenol used, in the presence of a basic catalyst. The formation of the resin which is accelerated when the temperature rises is difficult to control. It results in very diverse products according to the operating conditions and in particular according to the duration of the reaction. If the reaction is not stopped it continues until the formation of a solid product which is infusible and therefore cannot be spinned. To maintain the resin in conditions under which it can be worked, the reaction should be blocked by lowering the temperature and / or neutralizing the mixture. A resin in solution is then obtained, the characteristics of which, in particular of viscosity, vary according to the degree of progress of the reaction. The resin is crosslinkable and crosslinking can be accelerated in the presence of an acid catalyst. The crosslinking is all the faster the higher the temperature.

En pratique, à l'heure actuelle, seules les résines phénoplastes du type novolaque sont utilisées pour la production de fibres. On ne connait pas en effet de technique permettant de produire de façon avantageuse des fibres à partir de résols.In practice, at present, only phenolic resins of the novolak type are used for the production of fibers. There is indeed no known technique for advantageously producing fibers from resols.

La production des fibres de novolaque est obtenue traditionnellement par fusion de la résine thermofusible suivie du fibrage et du traitement en milieu aqueux ou gazeux avec l'agent de réticulation et le catalyseur.The production of novolak fibers is traditionally obtained by melting the hot-melt resin followed by fiberizing and treatment in an aqueous or gaseous medium with the crosslinking agent and the catalyst.

Ce traitement aboutissant à la réticulation est très long en raison de la nécessité de faire diffuser l'agent de réticulation et le catalyseur dans la fibre de résine solidifiée. Il peut s'étendre sur plusieurs heures.This treatment resulting in crosslinking is very long because of the need to diffuse the crosslinking agent and the catalyst in the solidified resin fiber. It can extend over several hours.

Il a été proposé d'accélérer le traitement en procédant à la formation des fibres à partir d'un mélange de la résine novolaque fondue avec l'agent de réticulation. Néanmoins la réticulation en phase gazeuse acide à température élevée et sous pression, qui fait suite au fibrage dans cette technique, est une opération délicate et qui se prête difficilement à un fonctionnement continu nécessaire pour des productions de grandes quantités dans des conditions économiques.It has been proposed to accelerate the treatment by proceeding to the formation of the fibers from a mixture of the molten novolak resin with the crosslinking agent. Nevertheless, the crosslinking in the acid gas phase at high temperature and under pressure, which follows fiberizing in this technique, is a delicate operation and which hardly lends itself to the continuous operation necessary for production of large quantities under economical conditions.

Dans le cas des résols, l'opération aboutissant à la formation des fibres est particulièrement délicate. Contrairement aux novolaques pour lesquelles le refroidissement après passage du mélange fondu dans la filière conduit à des fibres en quelque sorte figées et bien individualisées, même si la réticulation est à peine commencée, le fibrage opéré avec un résol dans un état convenant au filage, c'est-à-dire un résol dont l'évolution a été stoppée à un degré de condensation tel que la viscosité soit satisfaisante, conduit à la production de fibres non stabilisées qui restent collantes.In the case of resols, the operation leading to the formation of the fibers is particularly delicate. Unlike the novolaks for which the cooling after passage of the molten mixture in the die leads to fibers in a way frozen and well individualized, even if the crosslinking is barely started, the fibering operated with a resol in a state suitable for spinning, c that is to say a resol whose evolution has been stopped at a degree of condensation such that the viscosity is satisfactory, leads to the production of unstabilized fibers which remain sticky.

Il est également connu par la publication de brevet français FR 2 383 249 un procédé de production de fibres phénoplastes, et notamment de fibres à base de résine urée-formaldéhyde. Selon ce procédé, on prépare une composition comprenant la résine et un catalyseur de réticulation en ajustant sa viscosité avant son introduction dans une filière centrifuge, et les conditions de fibrage, liées à la nature de la composition à fibrer sont telles que la formation des fibres, leur séchage et leur réticulation sont effectués en trois étapes distinctes et successives. Ces conditions ne sont pas adaptées aux résines résols.It is also known from the publication of French patent FR 2 383 249 a process for producing phenoplast fibers, and in particular fibers based on urea-formaldehyde resin. According to this process, a composition is prepared comprising the resin and a crosslinking catalyst by adjusting its viscosity before it is introduced into a centrifugal die, and the fiberizing conditions, linked to the nature of the composition to be fiberized, are such that the formation of fibers , their drying and crosslinking are carried out in three distinct and successive stages. These conditions are not suitable for resin resins.

L'invention se propose de fournir un procédé de production de fibres à partir de résols.The invention proposes to provide a process for the production of fibers from resols.

A cette fin, selon l'invention, la résine utilisée, la nature et les proportions des produits éventuellement ajoutés, notamment un catalyseur de réticulation, sont choisies pour constituer un mélange dont les caractéristiques, notamment de viscosité, conviennent pour la formation de fibres par passage dans une filière.To this end, according to the invention, the resin used, the nature and the proportions of the products possibly added, in particular a crosslinking catalyst, are chosen to constitute a mixture whose characteristics, in particular of viscosity, are suitable for the formation of fibers by passage in a sector.

La composition à fibrer dont les conditions de viscosité sont éventuellement ajustées par addition de solvants est immédiatement dirigée vers un organe faisant office de filière et qui est constitué par un centrifugeur. La composition introduite dans le centrifugeur recouvre la paroi périphérique intérieure du centrifugeur. Cette paroi est percée d'orifices par lesquels passe la composition. Cette dernière est projetée hors des orifices sous forme de minces filaments qui s'étirent en fibres et les orifices sont de dimensions telles que chacun d'eux donne naissance à une fibre distincte. Les conditions déterminant la cinétique de maturation des fibres formées, notamment le choix du catalyseur éventuel et de ses proportions, et les conditions de température de l'atmosphère environnante dans laquelle sont projetées les fibres, sont choisies de façon qu'au cours de leur trajectoire dans cette atmosphère jusqu'à leur réception, les fibres soient suffisamment réticulées et séchées pour garder une forme propre et ne collent pas les unes aux autres.The composition to be fiberized, the viscosity conditions of which are optionally adjusted by the addition of solvents, is immediately directed to a member acting as a die and which is consisting of a centrifuge. The composition introduced into the centrifuge covers the inner peripheral wall of the centrifuge. This wall is pierced with orifices through which the composition passes. The latter is projected out of the orifices in the form of thin filaments which stretch into fibers and the orifices are of dimensions such that each of them gives rise to a separate fiber. The conditions determining the maturation kinetics of the fibers formed, in particular the choice of the possible catalyst and of its proportions, and the temperature conditions of the surrounding atmosphere in which the fibers are projected, are chosen so that during their trajectory in this atmosphere until they are received, the fibers are sufficiently crosslinked and dried to keep a clean shape and do not stick to each other.

Une des principales difficultés rencontrées dans la formation des fibres à partir de résols est liée au fait qu'il faut utiliser des compositions très instables. Le problème ne se pose pas dans le cas des novolaques. Pour ces dernières, leur caractère thermofusible permet de conduire de façon entièrement distincte la formation des fibres d'une part et la réticulation de la résine d'autre part. D'une certaine façon dans la production de fibres novolaques, la stabilité de la résine est largement mise à profit. Pour les résols, les compositions en solution ne permettent pas une séparation des deux opérations. La formation des fibres doit donc se dérouler en même de temps que processus de réticulation-séchage conduisant à des fibre "stabilisées".One of the main difficulties encountered in the formation of fibers from resols is linked to the fact that very unstable compositions must be used. The problem does not arise in the case of novolaks. For the latter, their hot-melt nature makes it possible to conduct the formation of the fibers on the one hand and the crosslinking of the resin on the other hand in a completely separate manner. In a certain way in the production of novolak fibers, the stability of the resin is largely used. For the resols, the compositions in solution do not allow a separation of the two operations. The formation of the fibers must therefore take place at the same time as the crosslinking-drying process leading to "stabilized" fibers.

Par ce qualificatif nous désignons dans ce mémoire des fibres dont l'évolution est suffisante pour leur permettre de conserver une forme propre même si les qualités mécaniques finales des fibres complètement réticulées ne sont pas encore atteintes. En outre, l'état de surface des fibres est tel qu'elles ne risquent plus de coller les unes aux autres lorsqu'elles sont rassemblées et donc au contact les unes des autres. La "stabilité" des fibres s'apprécie bien entendu par rapport aux conditions qui sont celles de leur préparation. Au cours de cette production, comme nous le verrons dans la suite, les fibres ne sont soumises qu'à des contraintes mécaniques limitées.By this qualifier we designate in this thesis fibers whose evolution is sufficient to allow them to maintain their own shape even if the final mechanical qualities of the completely crosslinked fibers are not yet reached. In addition, the surface condition of the fibers is such that they no longer risk sticking to each other when they are combined and therefore in contact with each other. The "stability" of the fibers is of course appreciated in relation to the conditions which are those of their preparation. During this production, as we will see below, the fibers are only subjected to limited mechanical stresses.

En d'autres termes, la préparation des fibres résols est soumise à des exigences contradictoires. D'une part il peut paraître souhaitable de former un mélange capable d'accélérer le processus d'évolution, et d'autre part lorsqu'un tel mélange est effectivement réalisé, il est difficile de contrôler suffisamment l'évolution de façon à maintenir le mélange dans des conditions adéquates pour le passage dans une filière et l'étirage des fibres.In other words, the preparation of resolated fibers is subject to conflicting requirements. On the one hand it may seem desirable to form a mixture capable of accelerating the evolution process, and on the other hand when such a mixture is actually carried out, it is difficult to sufficiently control the evolution so as to maintain the mixing under conditions suitable for passing through a die and drawing the fibers.

Pour pouvoir fibrer les compositions utilisées selon l'invention et compte tenu du fait qu'elles évoluent rapidement vers un état dans lequel précisément elles ne pourraient plus servir à la formation des fibres, il faut faire en sorte que le mélange formé soit très rapidement utilisé.To be able to fiberize the compositions used according to the invention and taking into account the fact that they evolve rapidly towards a state in which precisely they could no longer be used for the formation of fibers, it is necessary to ensure that the mixture formed is very quickly used .

Selon l'invention, on procède donc à la formation du mélange au fur et à mesure de son utilisation. Une fois le mélange constitué, les moyens utilisés pour produire les fibres doivent retenir ce mélange un temps aussi court que possible.According to the invention, the mixture is therefore formed as it is used. Once the mixture has been formed, the means used to produce the fibers must retain this mixture for as short a time as possible.

Le choix d'un procédé utilisant un centrifugeur faisant office de filière répond bien à ces conditions.The choice of a process using a centrifuge acting as a die meets these conditions well.

La quantité de composition maintenue dans le centrifugeur peut être extrêmement faible. Elle peut correspondre à la quantité passant en quelques secondes, de sorte que le temps de séjour moyen soit très court et que l'on ne risque pas de "figer" la composition avant son passage par les orifices.The amount of composition held in the centrifuge can be extremely small. It can correspond to the quantity passing in a few seconds, so that the average residence time is very short and that there is no risk of "freezing" the composition before it passes through the orifices.

Les fibres étant projetées hors du centrifugeur, il faut les stabiliser le plus vite possible. L'intervalle de temps séparant l'apparition des fibres à la sortie du centrifugeur de leur dépôt sur l'organe collecteur est nécessairement limité par les dimensions de l'installation utilisée.The fibers being projected out of the centrifuge, they must be stabilized as quickly as possible. The time interval separating the appearance of the fibers at the outlet of the centrifuge from their deposition on the collecting member is necessarily limited by the dimensions of the installation used.

Pour obtenir une stabilisation de la résine, il convient à la fois dans ce court laps de temps de sécher et de réticuler les fibres. Pour ces deux processus, il est avantageux de chauffer l'air environnant le centrifugeur. Toutefois, la température de traitement est limitée. Même si les fibres ne sont pas à proprement parler "thermofusibles" comme le sont les fibres novolaques non réticulées, elles sont sensibles à la chaleur. Nous le verrons par la suite, cette propriété est avantageusement utilisée pour "refondre" superficiellement les fibres et procéder ainsi à ce que l'on nomme un auto- liage. La vigueur du traitement thermique que peuvent subir les fibres est surtout limitée en raison du risque d'apparition de bulles par évaporation trop brutale de l'eau ou des solvants présents dans la composition à l'origine.In order to obtain stabilization of the resin, it is advisable both to dry and to crosslink the fibers in this short period of time. For these two processes, it is advantageous to heat the air surrounding the centrifuge. However, the processing temperature is limited. Even if the fibers are not strictly speaking "hot-melt" as are the non-crosslinked novolak fibers, they are sensitive to heat. We will see it later, this property is advantageously used to superficially "melt" the fibers and thus proceed to what is called a self-binding. The strength of the heat treatment which the fibers can undergo is above all limited due to the risk of the appearance of bubbles by too sudden evaporation of the water or of the solvents present in the composition at the origin.

La formation de ces bulles n'est pas souhaitable. Les bulles rompent l'homogénéité de la structure des fibres et nuisent notamment à leur propriétés mécaniques.The formation of these bubbles is not desirable. The bubbles break the homogeneity of the structure of the fibers and in particular harm their mechanical properties.

Pour cette raison, la température des fibres dans l'atmosphère environnant le centrifugeur est de préférence maintenue inférieure à la température d'ébullition de l'eau, ou du mélange eau/solvant, présents dans la composition. Pour les mélanges les plus utiles qui sont présentés de façon plus détaillée dans la suite, la température à ne pas dépasser correspond approximativement à celle d'ébullition de l'eau. Pour éviter tout risque d'apparition des bulles la température des fibres, au moins dans la région la plus voisine du centrifugeur, ne dépasse pas 80° C.For this reason, the temperature of the fibers in the atmosphere surrounding the centrifuge is preferably kept below the boiling temperature of the water, or of the water / solvent mixture, present in the composition. For the most useful mixtures which are presented in more detail below, the temperature not to be exceeded corresponds approximately to that of boiling water. To avoid any risk of bubbles appearing, the temperature of the fibers, at least in the region closest to the centrifuge, does not exceed 80 ° C.

La température de l'atmosphère elle-même peut être sensiblement supérieure à celle des fibres par suite du refroidissement provoqué sur celles-ci par l'évaporation. Nous verrons dans les exemples que la température des gaz peut atteindre et même dépasser 200° C.The temperature of the atmosphere itself can be significantly higher than that of the fibers as a result of the cooling caused on them by evaporation. We will see in the examples that the gas temperature can reach and even exceed 200 ° C.

Il est possible de prévoir un traitement thermique progressif. Par exemple, les fibres sont soumises à une température qui croit lorsqu'elles s'éloignent du centrifugeur. Dans cette hypothèse, les échanges s'effectuant très rapidement en raison de la finesse des fibres, la réticulation progressant et le séchage s'effectuant, il est possible d'atteindre dans les zones éloignées du centrifugeur des températures supérieures aux températures limites indiquées ci-dessus.It is possible to provide a progressive heat treatment. For example, the fibers are subjected to a temperature which increases when they move away from the centrifuge. In this hypothesis, the exchanges taking place very quickly due to the fineness of the fibers, the crosslinking progressing and the drying taking place, it is possible to reach in the areas remote from the centrifuge temperatures higher than the limit temperatures indicated above. above.

Dans tous les cas les conditions de traitement thermique et de séchage sont améliorées par circulation d'air sur les fibres. Le courant gazeux chaud est de préférence animé d'une vitesse relativement faible losrqu'il est dirigé transversalment au sens de projection des fibres hors du centrifugeur pour éviter de rabattre trop tôt les fibres les unes sur les autres alors qu'elles ne sont pas encore parfaitement stabilisées.In all cases the conditions of heat treatment and drying are improved by circulation of air over the fibers. The hot gas stream is preferably driven at a relatively low speed when it is directed transversely to the direction of projection of the fibers out of the centrifuge to avoid folding the fibers too early on each other when they are not yet perfectly stabilized.

Dans les conditions opératoires qui seront détaillées ultérieurement en faisant référence au dispositif utilisé, nous verrons que les fibres sont maintenues un temps relativement court dans les conditions qui favorisent leur stabilisation avant qu'elles ne soient rassemblées. Dans ce temps qui est de l'ordre de la seconde, la stabilisation des fibres est obtenue grâce aux conditions de traitement qui viennent d'être précisées, mais aussi par un choix de compositions particulièrement approprié.In the operating conditions which will be detailed later with reference to the device used, we will see that the fibers are maintained for a relatively short time under the conditions which favor their stabilization before they are combined. In this time which is of the order of a second, the stabilization of the fibers is obtained thanks to the treatment conditions which have just been specified, but also by a particularly suitable choice of compositions.

Les conditions à respecter dans ce sens sont d'abord liées à la nature de la résine. Elles dépendent aussi dans une moindre mesure des autres constituants du mélange.The conditions to be observed in this sense are first linked to the nature of the resin. They also depend to a lesser extent on the other constituents of the mixture.

Il convient tout d'abord que la résine ou le mélange résinecatalyseur, présente une viscosité convenable pour le mode de formation des fibres envisagé. Expérimentalement, en tenant compte des variations possibles de force centrifuge et aussi de dimensions des orifices du centrifugeur, une viscosité de l'ordre de 500 à 30000 mPas et de préférence de 1500 à 10000 mPas est avantageusement choisie. Dans ces conditions de viscosité, la résine ou le mélange n'est ni trop fluide, ce qui conduirait à une rupture prématurée des filaments engendrant des gouttelettes et/ou des produits insuffisamment étirés, ni trop visqueux, ce qui obligerait à l'utilisation d'orifices relativement gros et les fibres obtenues ne répondraient pas aux caractéristiques de finesse ordinairement recherchées.First of all, the resin or resin-catalyst mixture should have a viscosity suitable for the mode of fiber formation envisaged. Experimentally, taking into account possible variations in centrifugal force and also in the dimensions of the orifices of the centrifuge, a viscosity of the order of 500 to 30,000 mPas and preferably from 1,500 to 10,000 mPas is advantageously chosen. Under these viscosity conditions, the resin or the mixture is neither too fluid, which would lead to premature rupture of the filaments generating droplets and / or products that are insufficiently drawn, or too viscous, which would require the use of relatively large orifices and the fibers obtained would not meet the characteristics of fineness ordinarily sought.

La viscosité de la composition utilisée est déterminée en premier lieu par celle de la résine, elle-même dépendant de la façon dont la résine est préparée. Il faut ainsi prendre en considération le temps et la température de réaction, ainsi que le rapport molaire du formol et du phénol de départ. La condensation devant être interrompue lorsque la viscosité convenant au filage est atteinte. La viscosité de la résine peut cependant être modifiée par l'adjonction de solvants. La résine utilisée présente de préférence une masse moléculaire comprise entre 100 et 1000 et plus particulièrement entre 400 et 800. On prépare de préférence la résine à partir de phénol et de formaldéhyde introduits dans un rapport molaire du formol au phénol compris entre 1,3 et 1,7.The viscosity of the composition used is determined first of all by that of the resin, which itself depends on how the resin is prepared. It is thus necessary to take into consideration the reaction time and temperature, as well as the molar ratio of the formalin and the starting phenol. Condensation must be stopped when the viscosity suitable for spinning is reached. The viscosity of the resin can however be modified by the addition of solvents. The resin used preferably has a molecular mass of between 100 and 1000 and more particularly between 400 and 800. The resin is preferably prepared from phenol and formaldehyde introduced in a molar ratio of formaldehyde to phenol of between 1.3 and 1.7.

Dans la préparation de la composition, lorsqu'on ajoute un catalyseur il est aussi nécessaire de tenir compte de son influence. Celui-ci est ordinairement introduit en solution, notamment aqueuse.In the preparation of the composition, when adding a catalyst it is also necessary to take into account its influence. This is usually introduced in solution, in particular aqueous.

Les résols sont peu miscibles à l'eau. Pour obtenir un mélange homogène, ce qui est indispensable pour la régularité du fibrage, un tiers solvant est avantageusement utilisé en quantité aussi faible que possible. On utilise comme tiers solvant un composé à la fois miscible à l'eau et à la résine et qui soit susceptible de s'éliminer facilement lors du traitement ultérieur des fibres. Avantageusement le tiers solvant est un alcool, notamment du méthanol.Resols are hardly miscible with water. To obtain a homogeneous mixture, which is essential for the regularity of fiberizing, a third solvent is advantageously used in as small a quantity as possible. A compound which is both miscible with water and with resin and which is capable of being easily removed during the subsequent treatment of the fibers is used as a third solvent. Advantageously, the third solvent is an alcohol, in particular methanol.

Eventuellement la viscosité de l'ensemble ajouté à la résine peut être réglée elle aussi pour éviter qu'au moment du mélange on n'observe une trop forte modification de la viscosité.Optionally, the viscosity of the assembly added to the resin can also be adjusted to avoid that, at the time of mixing, a too strong modification of the viscosity is observed.

Lorsqu'on souhaite modérer le catalyseur, il est possible d'introduire simultanément des agents épaississants, par exemple des glycols, et de préférence du di- ou du triéthylèneglycol. Au lieu de modérer le catalyseur en le diluant avec de l'eau, ce qui conduit à une trop grande fluidité d'une part, et d'autre part nécessite la présence d'une grande quantité de tiers solvants, on introduit ces agents épaississants qui tout en permettant d'atteindre une viscosité finale plus élevée, favorisent également l'homogénéisation du mélange.When it is desired to moderate the catalyst, it is possible to simultaneously introduce thickening agents, for example glycols, and preferably di- or triethylene glycol. Instead of moderating the catalyst by diluting it with water, which leads to too great a fluidity on the one hand, and on the other hand requires the presence of a large amount of third-party solvents, these thickening agents are introduced which, while allowing a higher final viscosity to be reached, also promote the homogenization of the mixture.

Les catalyseurs de réticulation utilisés sont des acides forts, minéraux ou organiques, seuls ou en mélange. On utilise de préférence des acides tels que l'acide sulfurique, l'acide phosphorique ou l'acide chlorhydrique et leurs mélanges en solution aqueuse.The crosslinking catalysts used are strong acids, mineral or organic, alone or as a mixture. Acids such as sulfuric acid, phosphoric acid or hydrochloric acid and their mixtures in aqueous solution are preferably used.

L'utilisation d'un catalyseur en solution permet une bonne dispersion de celui-ci au sein de la résine sous la réserve que la miscibilité ait été assurée comme nous l'avons indiqué ci-dessus. La dispersion du catalyseur dans la résine est un élément déterminant pour la façon dont la réticulation s'opère. Une bonne dispersion favorise bien entendu une réticulation rapide et homogène, ce qui est souhaitable dans les conditions utilisées selon l'invention.The use of a catalyst in solution allows a good dispersion thereof within the resin provided that the miscibility has been ensured as we have indicated above. The dispersion of the catalyst in the resin is a determining factor for the way in which the crosslinking takes place. Good dispersion naturally favors rapid and homogeneous crosslinking, which is desirable under the conditions used according to the invention.

Les caractéristiques des compositions filables utilisées selon l'invention peuvent être encore modifiées pour améliorer la formation et l'étirage des fibres.The characteristics of the spun compositions used according to the invention can be further modified to improve the formation and drawing of the fibers.

Il est connu d'utiliser dans ce sens des petites quantités (moins de 2 % en poids) de polyoxyoléfines à très longues chaînes qui favorisent l'étirage des fibres sans rupture, même pour des diamètres extrêmement fins. Des produits de ce type sont par exemple ceux commercialisés sous le nom "POLYOX" (arque déposée).It is known to use in this sense small amounts (less than 2% by weight) of polyoxyolefins with very long chains which promote the drawing of fibers without breaking, even for extremely fine diameters. Products of this type are for example those sold under the name "POLYOX" (registered arch).

Il est également usuel dans les procédés de formation de fibres à partir de résines synthétiques d'ajouter de faibles proportions d'un agent tensio-actif, toujours pour améliorer les caractéristiques lors du fibrage, et éviter notamment les ruptures capillaires précoces. De préférence, ce sont des tensio-actifs non ioniques, tels les alcools gras de sorbitan ou cationiques, qui présentent une meilleure stabilité en milieu acide. Des agent tensio-actifs préférés sont ceux commercialisés sous les noms "TWEEN" et "SPAN" (marques déposées). Ils sont introduits dans la composition à raison de 0,5 à 3 % en poids.It is also usual in the processes of formation of fibers from synthetic resins to add small proportions of a surfactant, always to improve the characteristics during fiberizing, and in particular to avoid early hair breaks. Preferably, these are nonionic surfactants, such as sorbitan or cationic fatty alcohols, which exhibit better stability in an acid medium. Preferred surfactants are those sold under the names "TWEEN" and "SPAN" (registered trademarks). They are introduced into the composition in an amount of 0.5 to 3% by weight.

D'autres caractéristiques de l'invention apparaissent dans la suite de la description qui fait référence aux planches de dessins dans lesquelles:

  • - la figure 1 est une vue schématique partiellement en coupe d'une installation pour la formation de fibres selon l'invention,
  • - la figure 2 montre en coupe la structure d'un centrifugeur utilisé selon l'invention,
  • - la figure 3 est une vue partielle en coupe d'un centrifugeur à plusieurs rangées d'orifices.
Other characteristics of the invention appear in the following description which refers to the drawing boards in which:
  • FIG. 1 is a schematic view partially in section of an installation for the formation of fibers according to the invention,
  • FIG. 2 shows in section the structure of a centrifuge used according to the invention,
  • - Figure 3 is a partial sectional view of a centrifuge with several rows of orifices.

L'installation schématisée à la figure 1 est particulièrement représentative de celles qui peuvent être utilisées selon l'invention. On y effectue la mise en condition de la composition, le fibrage de cette composition et la stabilisation des fibres formées.The installation shown diagrammatically in FIG. 1 is particularly representative of those which can be used according to the invention. It performs the conditioning of the composition, the fiberizing of this composition and the stabilization of the fibers formed.

La resine préalablement préparée et contenant éventuellement les divers additifs de fibrage est placée dans un réservoir 1 dans lequel elle est maintenue à un température qui permet sa conservation.The resin previously prepared and optionally containing the various fiberizing additives is placed in a tank 1 in which it is maintained at a temperature which allows its conservation.

La résine à l'état liquide prélevée dans le réservoir 1 par des moyens appropriés à son état: pompe, vis, etc... est conduite en quantité déterminée dans un mélangeur 2. Le mélangeur reçoit également éventuellement en quantités dosées le catalyseur provenant d'un réservoir tel que représenté en 24.The resin in the liquid state taken from the tank 1 by means appropriate to its state: pump, screw, etc. is conducted in a determined quantity in a mixer 2. The mixer also optionally receives in metered quantities the catalyst originating from 'a tank as shown in 24.

L'opération de mélange est très vigoureuse pour obtenir une composition aussi homogène que possible.The mixing operation is very vigorous to obtain a composition that is as homogeneous as possible.

Le volume offert dans le mélangeur est faible pour que la composition y séjourne un temps aussi bref que possible. La composition est ensuite envoyée directement dans le dispositif de centrifugation.The volume offered in the mixer is small so that the composition stays there as short as possible. The composition is then sent directly to the centrifuge device.

Pour réduire le temps séparant l'opération de mélange de celle de formation des fibres, la canalisation 8 conduisant la composition à fibrer dans le dispositif de centrifugation est aussi courte que possible. Autrement dit, le mélangeur 2 est situé avantageusement à proximité du dispositif de centrifugation.To reduce the time separating the mixing operation from that of fiber formation, the line 8 leading the composition to be fiberized in the centrifuge device is as short as possible. In other words, the mixer 2 is advantageously located near the centrifuge device.

La formation des filaments à partir de la composition est conduite dans un dispositif de centrifugation représenté aux figures 1 et 2.The formation of the filaments from the composition is carried out in a centrifuge device shown in Figures 1 and 2.

Le dispositif comprend un centrifugeur 3 fixé sur un arbre 4 lequel est entraîné en rotation par un moteur électrique 5 par l'intermédiaire de courroies 6. L'arbre 4 est monté sur des roulements 7.The device comprises a centrifuge 3 fixed on a shaft 4 which is rotated by an electric motor 5 by means of belts 6. The shaft 4 is mounted on bearings 7.

L'arbre 4 est creux. La canalisation 8 conduisant la composition au centrifugeur est logée dans cet arbre.The shaft 4 is hollow. Line 8 leading the composition to the centrifuge is housed in this tree.

Le dispositif de centrifugation lui-même comprend un panier 9 sur le fond duquel la composition est déversée. Le panier est percé sur sa paroi périphérique 10 d'orifices 11 régulièrement espacés.The centrifuge device itself comprises a basket 9 on the bottom of which the composition is poured. The basket is pierced on its peripheral wall 10 with regularly spaced holes 11.

Sous l'effet de la rotation, la composition atteint la face intérieure de la paroi 10 et s'échappe par les orifices 11 sous forme de gros filets de composition, qui sont projetés sur la paroi périphérique 12 du centrifugeur proprement dit 3.Under the effect of the rotation, the composition reaches the inner face of the wall 10 and escapes through the orifices 11 in the form of large composition nets, which are projected onto the peripheral wall 12 of the centrifuge proper 3.

La présence du panier 9 permet une première égalisation de la distribution de la composition sur la paroi intérieure périphérique du centrifugeur. L'utilisation d'un panier est d'autant plus avantageuse que le centrifugeur est de plus grande dimension. Pour un centrifugeur de grand diamètre, la distribution "naturelle" de la composition risque davantage d'être déséquilibrée. Il est très important pour la qualité des fibres d'avoir en tout point du centrifugeur une même "réserve", c'est-à-dire une même épaisseur de composition pour que les conditions de centrifugation soient partout les mêmes et donc que les fibres soient formées dans les mêmes conditions.The presence of the basket 9 allows a first equalization of the distribution of the composition on the inner peripheral wall of the centrifuge. The use of a basket is all the more advantageous when the centrifuge is larger. For a large diameter centrifuge, the "natural" distribution of the composition is more likely to be unbalanced. It is very important for the quality of the fibers to have at all points of the centrifuge the same "reserve", that is to say the same thickness of composition so that the centrifugation conditions are everywhere the same and therefore that the fibers are formed under the same conditions.

La composition qui forme la réserve s'échappe du centrifugeur par les orifices 14 disposés à la périphérie.The composition which forms the reserve escapes from the centrifuge through the orifices 14 arranged at the periphery.

Les orifices 14 ont des dimensions telles que chacun d'eux donne naissance à une seule fibre qui est ensuite projetée dans l'atmosphère environnante.The orifices 14 have dimensions such that each of them gives rise to a single fiber which is then projected into the surrounding atmosphere.

Le profil interne du centrifugeur est déterminé de façon à faciliter l'écoulement de la composition. Dans la forme présentée à la figure 2, les orifices sont précédés d'une partie de section triangulaire 15 qui conduit la composition vers les orifices 14. Ce profil évite notamment la stagnation de composition dans des angles morts, stagnation qui pourrait aboutir à des dépôts de résines réticulées.The internal profile of the centrifuge is determined so as to facilitate the flow of the composition. In the form presented in FIG. 2, the orifices are preceded by a part of triangular cross section 15 which leads the composition towards the orifices 14. This profile notably avoids the stagnation of composition in blind spots, stagnation which could lead to deposits of crosslinked resins.

La figure 2 montre un centrifugeur comportant une seule rangée d'orifices 14. Il est bien entendu possible d'utiliser un centrifugeur comportant plusieurs rangées d'orifices, comme cela est représenté à la figure 3. Il convient dans ce cas, de choisir la distance entre deux rangées successives de façon que les fibres formées ne risquent pas de se recoller avant d'être stabilisées. La distance entre deux orifices d'une même rangée est choisie également de façon à éviter que les fibres ne se recollent les unes aux autres.FIG. 2 shows a centrifuge comprising a single row of orifices 14. It is of course possible to use a centrifuge comprising several rows of orifices, as shown in FIG. 3. In this case, it is necessary to choose the distance between two successive rows so that the fibers formed do not risk re-sticking before being stabilized. The distance between two orifices in the same row is also chosen so as to prevent the fibers from sticking together.

Le profil du centrifugeur à plusieurs rangées d'orifices représenté à la figure 3 comprend également sur la face interne des rainures 26 dont la section va en diminuant lorsqu'on approche des orifices 14, lesquelles permettent une bonne circulation du matériau à fibrer vers chaque rangée d'orifices.The profile of the centrifuge with several rows of orifices represented in FIG. 3 also includes grooves 26 on the internal face, the section of which decreases when approaching the orifices 14, which allow good circulation of the material to be fiberized to each row orifices.

La quantité de composition dans le panier et le centrifugeur est maintenue au minimum nécessaire pour alimenter sans discontinuité les orifices 14. Pour la qualité et la régularité des fibres la "réserve" doit couvrir convenablement les orifices 14. Cette réserve doit cependant être faible pour écourter le temps de séjour.The amount of composition in the basket and the the centrifuge is kept at the minimum necessary to continuously feed the orifices 14. For the quality and regularity of the fibers, the "reserve" must suitably cover the orifices 14. This reserve must however be small to shorten the residence time.

En pratique, lorsque les conditions de fonctionnement sont bien établies, il est possible de faire en sorte qu'entre le début du mélange des constituants de la composition et la formation des fibres au passage des orifices 14 du centrifugeur, le temps soit inférieur à une minute et aussi faible qu'une dizaine de secondes. Dans ces conditions, même si la réaction de réticulation suit une cinétique rapide, l'évolution dans ce court laps de temps n'est pas telle qu'elle puisse faire obstacle au fibrage.In practice, when the operating conditions are well established, it is possible to ensure that between the start of the mixing of the constituents of the composition and the formation of the fibers as the orifices 14 of the centrifuge pass, the time is less than one minute and as weak as ten seconds. Under these conditions, even if the crosslinking reaction follows rapid kinetics, the evolution in this short period of time is not such that it can hinder fiberizing.

La composition est projetée hors du centrifugeur sous forme de filaments dont les dimensions sont déterminées par celles des orifices. Ordinairement, compte tenu des viscosités de la composition qui ont été indiquées précédemment et pour obtenir des fibres fines de l'ordre de 20 micromètres ou moins, les orifices ont un diamètre avantageusement inférieur à 1 mm et de préférence compris entre 0,2 et 0,8 mm. Pour des diamètres plus importants, et si les autres conditions demeurent inchangées, les fibres produites sont plus grosses. Pour retrouver des fibres plus fines, il est alors nécessaire d'effectuer une centrifugation plus violente et/ou de réduire le débit de composition par orifice.The composition is sprayed out of the centrifuge in the form of filaments, the dimensions of which are determined by those of the orifices. Ordinarily, taking into account the viscosities of the composition which have been indicated above and in order to obtain fine fibers of the order of 20 micrometers or less, the orifices have a diameter advantageously less than 1 mm and preferably between 0.2 and 0 , 8 mm. For larger diameters, and if the other conditions remain unchanged, the fibers produced are larger. To find finer fibers, it is then necessary to carry out a more violent centrifugation and / or to reduce the flow of composition per orifice.

A l'origine les fibres sont projetées et s'étirent sensiblement dans le plan perpendiculaire à l'axe de rotation du centrifugeur. Elles se développent en spirales qui peuvent s'étendre à des distances relativement importantes du centrifugeur lorsque l'accélération initiale est élevée. La trajectoire des fibres dans le plan qui peut atteindre un mètre ou plus, est habituellement limitée pour des raisons d'encombrement de l'enceinte de réception 19.Originally the fibers are projected and stretch substantially in the plane perpendicular to the axis of rotation of the centrifuge. They develop in spirals which can extend at relatively large distances from the centrifuge when the initial acceleration is high. The path of the fibers in the plane, which can reach a meter or more, is usually limited for reasons of the size of the receiving enclosure 19.

Dans le cas représenté, la trajectoire des fibres est limitée par soufflage d'un courant gazeux le long des parois 16, suffisamment intense pour rabattre les fibres avant qu'elles n'atteignent ces parois. Le soufflage peut être effectué par exemple au moyen d'une série de buses 18 disposée le long d'un conduit 17 d'alimentation en air comprimé. Les buses 18 sont de préférence suffisamment proches les unes des autres pour que les jets fusionnent très rapidement et constituent une nappe gazeuse pratiquement continue qui fait obstacle au passage des fibres.In the case shown, the path of the fibers is limited by blowing a gas stream along the walls 16, sufficiently intense to fold the fibers before they reach these walls. The blowing can be carried out for example by means of a series of nozzles 18 disposed along a conduit 17 for supplying compressed air. The nozzles 18 are preferably close enough to each other so that the jets fuse very quickly and constitute a practically continuous gas layer which obstructs the passage of the fibers.

La modification de la trajectoire des fibres imposée par le courant gazeux longeant la paroi 16 introduit certaines turbulences dans le mouvement qui se développe jusque là de façon très régulière. L'observation stroboscopique fait apparaître en effet que dans leur trajectoire jusqu'au voisinage de la paroi 16, les spirales de fibres se développent très régulièrement. Autrement dit les fibres, à ce stade de leur formation, progressent en restant bien individualisées. Le traitement selon l'invention qui aboutit à la stabilisation des fibres commence au cours de cette progression.The modification of the trajectory of the fibers imposed by the gaseous current along the wall 16 introduces certain turbulences in the movement which has hitherto developed very regularly. Stroboscopic observation indeed shows that in their trajectory to the vicinity of wall 16, the spirals of fibers develop very regularly. In other words the fibers, at this stage of their formation, progress while remaining well individualized. The treatment according to the invention which results in the stabilization of the fibers begins during this progression.

Les fibres dés le début de leur trajet vers la paroi 16 de l'enceinte de réception 19, sont soumises au traitement thermique qui permet d'accélérer sensiblement la cinétique de réticulation du mélange et favorise l'élimination d'eau et/ou de solvants présents dans les fibres.The fibers from the start of their path towards the wall 16 of the receiving enclosure 19, are subjected to the heat treatment which makes it possible to substantially accelerate the kinetics of crosslinking of the mixture and promotes the elimination of water and / or solvents present in the fibers.

Ce traitement thermique est avantageusement obtenu au moyen de courants gazeux chauds disposés sur la trajectoire des fibres entre la sortie du centrifugeur et le point où elles sont rabattues. Les cou, rants gazeux chauds sont dirigés sur la trajectoire des fibres avec une vitesse et à une température telles que l'on puisse limiter au maximum la modification de trajectoire et, par suite, les risques de collage des fibres non encore stabilisées.This heat treatment is advantageously obtained by means of hot gas streams arranged on the path of the fibers between the outlet of the centrifuge and the point where they are folded down. The hot gaseous layers are directed on the path of the fibers with a speed and at a temperature such that the modification of the path can be limited as much as possible and, consequently, the risks of sticking of the fibers not yet stabilized.

Le rôle de ces gaz est d'abord de maintenir les fibres à une température favorable à la réticulation et au séchage. Etant donné la faible inertie thermique des fibres dans les conditions de finesses dans lesquelles elles se trouvent, les échanges thermiques sont quasi instantanés, indépendamment de la vitesse de circulation des gaz.The role of these gases is first of all to maintain the fibers at a temperature favorable to crosslinking and drying. Given the low thermal inertia of the fibers under the fineness conditions in which they are found, the heat exchanges are almost instantaneous, independently of the speed of circulation of the gases.

Pour éviter une modification importante de la trajectoire des fibres, la vitesse des gaz est de préférence maintenue inférieure à 20 m/s.To avoid a significant change in the path of the fibers, the speed of the gases is preferably kept below 20 m / s.

Nous avons vu plus haut qu'il pouvait être avantageux de soumettre les fibres à différentes conditions de température sur leur trajet. La figure 1 présente une double alimentation en gaz chauds. Ces deux alimentations sont faites à partir de chambres 20 et 21 disposées de façon concentrique autour du centrifugeur. Les chambres 20 et 21 sont alimentées par un ou plusieurs brûleurs à gaz par l'intermédiaire de canalisations non représentées. Elles sont séparées de l'enceinte de réception 19 par des grilles 22 largement ouvertes laissant passer les gaz à faible vitesse.We have seen above that it could be advantageous to subject the fibers to different temperature conditions along their path. Figure 1 shows a double supply of hot gases. These two supplies are made from chambers 20 and 21 arranged concentrically around the centrifuge. The chambers 20 and 21 are supplied by one or more gas burners by means of pipes not shown. They are separated from the receiving enclosure 19 by widely open grids 22 letting the gases pass at low speed.

L'installation représentée comporte deux chambres d'émission de gaz chauds, il est bien entendu possible de régler la température des gaz de ces deux chambres indépendamment l'unes de l'autre. Il est aussi possible de prévoir un nombre plus important de chambres d'émission des gaz pour contrôler encore mieux la progression des conditions de traitement des fibres.The installation shown comprises two hot gas emission chambers, it is of course possible to regulate the temperature of the gases of these two chambers independently of one another. It is also possible to provide a larger number of gas emission chambers to control even better the progress of the conditions for treating the fibers.

Il est préférable, de faire en sorte que les gaz émis sur le trajet des fibres ne viennent pas directement au contact du centrifugeur. En effet, dans ce cas, il faut éviter un échauffement qui pourrait aboutir à une modification prématurée de la composition dans le centrifugeur.It is preferable to ensure that the gases emitted on the path of the fibers do not come directly into contact with the centrifuge. In fact, in this case, it is necessary to avoid overheating which could lead to a premature modification of the composition in the centrifuge.

Pour la même raison, il peut être avantageux de protéger le centrifugeur contre la chaleur provenant de la chambre 20 voisine en interposant par exemple un serpentin 25 entourant l'arbre 4 et le sommet du centrifugeur, et dans lequel circule de l'eau de refroidissement.For the same reason, it may be advantageous to protect the centrifuge against heat coming from the neighboring chamber 20 by interposing for example a coil 25 surrounding the shaft 4 and the top of the centrifuge, and in which cooling water circulates .

La longueur de la trajectoire nécessaire avant de rassembler les fibres est déterminée en même temps que les conditions de température des gaz pour chaque composition traitée, étant entendu qu'il est nécessaire dans tous les cas de recueillir des fibres suffisamment séchées et réticulées pour qu'elles ne risquent pas de se coller les unes aux autres.The length of the path required before to gather the fibers is determined at the same time as the gas temperature conditions for each composition treated, it being understood that in all cases it is necessary to collect fibers sufficiently dried and crosslinked so that they do not risk sticking to each other.

Avantageusement, la distance séparant le centrifugeur du tapis de réception est telle que le temps mis par les fibres pour parcourir ce trajet soit compris entre 0,1 et 2 s.Advantageously, the distance separating the centrifuge from the receiving belt is such that the time taken by the fibers to travel this path is between 0.1 and 2 s.

Les fibres portées par les gaz se déposent sur un tapis convoyeur 23 où elles constituent un feutre de fibres enchevêtrées.The fibers carried by the gases are deposited on a conveyor belt 23 where they constitute a felt of entangled fibers.

En plus des chambres 20 et 21 par lesquelles les gaz chauds sont introduits, il est possible de modifier les conditions de température et de circulation des fibres en dégageant des ouvertures sur les parois 16 de l'enceinte 19 pour laisser pénétrer de l'air avoisinant.In addition to the chambers 20 and 21 through which the hot gases are introduced, it is possible to modify the temperature and circulation conditions of the fibers by clearing openings on the walls 16 of the enclosure 19 to allow neighboring air to penetrate. .

Dans ce cas, l'air entre dans la chambre sous l'effet de la dépression qui y est entretenue par aspiration des gaz sous le convoyeur. Les moyens d'aspiration sont constitués par un caisson 26 disposé sous le convoyeur et d'un ventilateur non représenté.In this case, the air enters the chamber under the effect of the vacuum which is maintained there by suction of the gases under the conveyor. The suction means consist of a box 26 disposed under the conveyor and a fan, not shown.

Les conditions énoncées plus haut selon l'invention permettent de recueillir des fibres dans lesquelles le processus de réticulation est très avancé et ceci en un temps très bref. Si le temps de séjour complet des fibres dans l'enceinte de réception est très court, il peut se produire que les fibres n'aient pas atteint un degré de maturation (ou de réticulation) permettant de leur conférer les meilleures propriétés possibles. Dans ce cas, il est avantageux de compléter la réticulation par un passage très bref en étuve.The conditions set out above according to the invention make it possible to collect fibers in which the crosslinking process is very advanced and this in a very short time. If the complete residence time of the fibers in the receiving enclosure is very short, it may happen that the fibers have not reached a degree of maturation (or crosslinking) allowing them to be given the best possible properties. In this case, it is advantageous to complete the crosslinking by a very brief passage in an oven.

Contrairement à ce qui était ordinairement réalisé dans les techniques antérieures pour la préparation des fibres novolaques, il n'y a pas de diffusion d'agent de réticulation et/ou de catalyseur. Ce traitement final est uniquement thermique et peut donc être très bref et surtout réalisé par passage en continu dans une étuve appropriée.Contrary to what was ordinarily carried out in the prior techniques for the preparation of novolak fibers, there is no diffusion of crosslinking agent and / or catalyst. This final treatment is only thermal and can therefore be very brief and above all carried out by continuous passage in an appropriate oven.

Avantageusement, pour accélérer l'achévement de la réticulation, la température au cours d'un tel traitement thermique est supérieure à 100°C, et de préférence comprise entre 100 et 150° C.Advantageously, to accelerate the completion of the crosslinking, the temperature during such a heat treatment is greater than 100 ° C., and preferably between 100 and 150 ° C.

Dans ces conditions un traitement de 5 min ou moins suffit habituellement.Under these conditions a treatment of 5 min or less is usually sufficient.

A l'occasion de ce traitement thermique, bien que leur réticulation soit très avancée, lorsque les fibres conservent une faible thermoplasticité, il est possible en les soumettant à une brève élévation de température au-dessus de leur température de ramollissement de les lier les unes aux autres. Cette opération est avantageusement effectuée à une température comprise entre 200 et 240° C. On obtient ainsi un feutre dont les caractéristiques dimensionnelles et mécaniques sont fixées.During this heat treatment, although their crosslinking is very advanced, when the fibers retain a low thermoplasticity, it is possible by subjecting them to a brief rise in temperature above their softening temperature to bind them together to others. This operation is advantageously carried out at a temperature between 200 and 240 ° C. A felt is thus obtained whose dimensional and mechanical characteristics are fixed.

Exemple de préparation de fibres en présence d'un catalyseur.Example of fiber preparation in the presence of a catalyst. 1. Fabrication de la résine de base.1. Manufacture of the base resin.

On mélange dans un réacteur de 200 1 régulé en température:

  • - 1270 moles de phénol (99,5 % de pureté),
  • - 1330 moles d'eau, le mélange est porté à 50° C et on ajoute:
  • -1905 moles de paraformaldéhyde (96 % de pureté),
  • - 30 moles d'hydroxyde de sodium (en solution à 50 %).
The following are mixed in a temperature-controlled 200 liter reactor:
  • - 1270 moles of phenol (99.5% purity),
  • - 1330 moles of water, the mixture is brought to 50 ° C. and added:
  • -1,905 moles of paraformaldehyde (96% purity),
  • - 30 moles of sodium hydroxide (50% solution).

En 15 minutes on élève la température à 60° C, température qui est maintenue pendant 30 min. Ensuite en 55 min on élève la temperature à 98° C. Le mélange est maintenu à ce palier pendant 30 min. et on effectue un dernier palier à 80° C.In 15 minutes the temperature is raised to 60 ° C, which temperature is maintained for 30 min. Then in 55 min the temperature is raised to 98 ° C. The mixture is maintained at this level for 30 min. and a final step is carried out at 80 ° C.

La réaction est stoppée par refroidissement lorsque la viscosité souhaitée est atteinte. Celle-ci est mesurée par la méthode du tube à écoulement. L'arrêt de la réaction est obtenu par refroidissement à 25° C.The reaction is stopped by cooling when the desired viscosity is reached. This is measured by the flow tube method. The reaction is stopped by cooling to 25 ° C.

La résine obtenue présente une viscosité de 1000 mPas à 25° C. L'extrait sec constitue 70,5 % de sa masse. On conserve la résine à une température de 5 à 7° C.The resin obtained has a viscosity of 1000 mPas at 25 ° C. The dry extract constitutes 70.5% of its mass. The resin is stored at a temperature of 5 to 7 ° C.

2. Fabrication du prémélange.2. Manufacturing of the premix.

Dans une cuve de 25 muni d'un agitateur 6 pales à pas inversé, on charge 15 kg de la résine obtenue en 1 chauffée à 20° C.15 kg of the resin obtained in 1 heated to 20 ° C. are loaded into a tank of 25 fitted with a 6-blade agitator with reverse pitch.

On ajoute 0,225 kg de l'agent tensio-actif désigné sous le nom commercial "SPAN 20" marqùe déposée (ATLAS C°) sous agitation lente.0.225 kg of the surfactant designated under the trade name "SPAN 20", added mark (ATLAS C °), are added with slow stirring.

On ajoute ensuite sous agitation rapide (800 t/min) un mélange préparé auparavant de 0,225 kg de l'agent de fibrage commercialisé sous le nom "POLYOX WSRN 3000" marque déposée (UNION CARBIDE) dispersé dans 1,5 kg de méthanol.Then added with rapid stirring (800 rpm) a mixture previously prepared of 0.225 kg of the fiberizing agent sold under the name "POLYOX WSRN 3000" registered trademark (UNION CARBIDE) dispersed in 1.5 kg of methanol.

L'agitation est ensuite maintenue pendant 6 h à 100 t/min. La viscosité du prémélange fibrable est de 13000 mPas à 25°C.Stirring is then continued for 6 h at 100 rpm. The viscosity of the fiber premix is 13,000 mPas at 25 ° C.

3. Fabrication du catalyseur.3. Manufacture of the catalyst.

Dans un réacteur de 1,5 I régulé en température et agité, on mélange: 4,507 kg d'acide sulfurique (à 92,5 %), 1,765 kg d'acide phosphorique à 85 % de pureté et 0,295 kg d'eau. Le mélange est fait vers 50° C.In a 1.5 I temperature-regulated and stirred reactor, 4.507 kg of sulfuric acid (92.5%), 1.765 kg of phosphoric acid 85% purity and 0.295 kg of water are mixed. The mixing is done around 50 ° C.

Après refroidissement, on ajoute 3,432 kg de triéthylèneglycol.After cooling, 3.432 kg of triethylene glycol are added.

4. Fabrication du mélange pour former les fibres.4. Manufacture of the mixture to form the fibers.

On opère dans une installation qui permet de mélanger le prémélange et le catalyseur en continu. Cette installation est située près du dispositif de formation des fibres.We operate in an installation which allows the premix and the catalyst to be mixed continuously. This facility is located near the fiber formation device.

Elle comprend:

  • - une cuve double enveloppe régulée à 20° C d'où le prémélange est prélevé grâce à une pompe dosuse à engrenage,
  • - une cuve émaillée d'où le catalyseur est prélevé par une pompe doseuse à 3 pistons décalés à 120°C de façon à obtenir une alimentation régulière,
  • - un mélangeur constitué d'un rotor denté qui tourne dans un stator denté à une vitesse de 500 à 1000 tours/min.
She understands:
  • - a double-shell tank regulated at 20 ° C from which the premix is taken out using a dosose gear pump,
  • - an enamelled tank from which the catalyst is removed by a metering pump with 3 pistons offset at 120 ° C so as to obtain a regular supply,
  • - a mixer consisting of a toothed rotor which rotates in a toothed stator at a speed of 500 to 1000 revolutions / min.

Pour 100 parties de mélange, on dose le catalyseur à 7 parties.For 100 parts of the mixture, the catalyst is measured at 7 parts.

Le mélange utilisé pour former les fibres est selon les cas de 100 parties en poids de prémélange de résine pour 5 à 10 parties de catalyseur.The mixture used to form the fibers is, as the case may be, 100 parts by weight of resin premix for 5 to 10 parts of catalyst.

Ce mélange se présente sous une forme homogène avec une viscosité variant de 3500 à 5000 mPas à 25°C.This mixture is in a homogeneous form with a viscosity varying from 3500 to 5000 mPas at 25 ° C.

5. Formation des fibres.5. Fiber formation.

L'opération est conduite en continu dans une enceinte de section carrée, et de hauteur d'environ 2,5 m du type de celle représentée à la figure 1.The operation is carried out continuously in an enclosure with a square section, and with a height of approximately 2.5 m of the type shown in FIG. 1.

Le mélange obtenu en 4 est conduit par une canalisation du mélangeur dans le panier de réception.The mixture obtained in 4 is led by a pipe of the mixer in the receiving basket.

Le centrifugeur et le panier tournent à 3000 tours/min.The centrifuge and the basket rotate at 3000 rpm.

Le panier est percé de 40 trous de 1,2 mm de diamètre et le centrifugeur dont le diamètre est de 200 mm présente 150 trous de 0,5 mm de diamètre.The basket is pierced with 40 holes of 1.2 mm in diameter and the centrifuge whose diameter is 200 mm has 150 holes of 0.5 mm in diameter.

6. Séchage et réticulation.6. Drying and crosslinking.

Les fibres se déploient dans l'air soufflé par 5 chambres concentriques.The fibers deploy in the air blown by 5 concentric chambers.

La vitesse du gaz émis par ces chambres va croissant lorsqu'on s'éloigne du centrifugeur, assurant une déviation progressive des fibres.The speed of the gas emitted by these chambers increases as one moves away from the centrifuge, ensuring progressive deflection of the fibers.

L'air est chauffé à une température régulée entre 150 et 160° C.The air is heated to a regulated temperature between 150 and 160 ° C.

Une certaine quantité d'air à température ambiante est introduite par les parois formant les côtés de l'enceinte.A certain amount of air at room temperature is introduced through the walls forming the sides of the enclosure.

La température de l'air est de 80°C au niveau du convoyeur de réception.The air temperature is 80 ° C at the receiving conveyor.

Les fibres se déposent en une nappe continue de 50 cm environ de largeur, formée de longues fibres séchées et en grande partie réticulées.The fibers are deposited in a continuous sheet of approximately 50 cm in width, formed of long dried and largely crosslinked fibers.

Le réglage de l'aspiration permet, en contrôlant la température en bas de hotte, de faire varier le degré de réticulation.The regulation of the suction allows, by controlling the temperature at the bottom of the hood, to vary the degree of crosslinking.

7. Caractéristiques des fibres dans le feutre.7. Characteristics of fibers in felt.

Pour un débit de composition de 255 kg/jour, on récupère 166 kg/jour de fibres.For a composition throughput of 255 kg / day, 166 kg / day of fibers are recovered.

Les diamètres de fibres sont compris entre 2 et 19 µm. L'histogramme des diamètres est de type gaussien très resséré avec un diamètre moyen de 7 micromètres.The fiber diameters are between 2 and 19 µm. The histogram of the diameters is of very tight Gaussian type with an average diameter of 7 micrometers.

La résistance moyenne à la traction s'établit à environ 300 MPa.The average tensile strength is around 300 MPa.

La masse volumique du feutre est d'environ 20 kg/m3 et sa conductivité thermique de l'ordre de 35 mW/m°K pour une épaisseur de 80 mm.The density of the felt is approximately 20 kg / m 3 and its thermal conductivity on the order of 35 mW / m ° K for a thickness of 80 mm.

Le feutre obtenu préalablement peut être complètement réticulé par un passage à l'étuve 5 minutes à 120° C.The felt obtained previously can be completely crosslinked by passing through the oven for 5 minutes at 120 ° C.

Le feutre qui n'est pas complètement réticulé présente une certaine thermoplasticité. Ceci peut être mis à profit pour constituer un feutre auto- lié: A cet effet le feutre obtenu est soumis pendant 3 minutes à une température de l'ordre de 220° C en le comprimant légèrement.The felt which is not completely crosslinked has a certain thermoplasticity. This can be taken advantage of to constitute a self-bonding felt: For this purpose the felt obtained is subjected for 3 minutes to a temperature of the order of 220 ° C. by slightly compressing it.

On obtient ainsi un feutre ayant une cohésion qui le rend facilement manipulable.A felt is thus obtained having a cohesion which makes it easy to handle.

Exemple 2Example 2

On se place dans les mêmes conditions que précédemment mais en utilisant un centrifugeur à plusieurs rangées d'orifices comme représenté à la figure 3.The same conditions are used as above, but using a centrifuge with several rows of orifices as shown in FIG. 3.

La formation des fibres se fait en mettant le système en rotation à 3800 tours/min. Le panier 9 est percé de 6 trous de 2,5 mm de diamètre et le centrifugeur présente 4 rangées de 150 trous de 0,4 mm de diamètre.The fibers are formed by rotating the system at 3800 rpm. The basket 9 is pierced with 6 holes of 2.5 mm in diameter and the centrifuge has 4 rows of 150 holes of 0.4 mm in diameter.

Les conditions générales de séchage et de réticulation sont inchangées. On observe une bonne distribution des filets de fibres dans les plans horizontaux et verticaux.The general conditions for drying and crosslinking are unchanged. A good distribution of the fiber nets is observed in the horizontal and vertical planes.

On obtient avantageusement un débit de fibres stabilisées supérieur à celui obtenu avec une seule rangée d'orifices.Advantageously, a stabilized fiber flow rate is obtained which is greater than that obtained with a single row of orifices.

Claims (19)

1. Method of forming fibres based on resins of the resol type resulting from the condensation of formol and phenols in a molar ratio of formol to phenol in excess of characterised in that the composition used for forming the fibres is brought to a situation where it can be crosslinked and its viscosity is adjusted immediately prior to its introduction into a die or spinneret, this preparetion and adjustment being carried out continuously on a small quantity of composition, the composition thus prepered feeding a centrifugal die and passing through the orifices in this die, each orifice giving rise to one fibre projected into the atmosphere surrounding the die from which it is drawn, the constitution of the composition used and the conditions of temperature in the atmosphere surrounding the centrifugal die being chosen so that the fibres collected are sufficiently stabilised to retain a proper shape and not to stick to one another.
2. Method according to Claim 1, in which preparation of the resin includes the addition of a cross-linking catalyst.
3. Method according to Claim 1 or Claim 2 in which viscosity of the composition is adjusted to a value of between 500 and 30,000 mPas.
4. Method according to Claim 3, in which the viscosity of the composition is adjusted to a value comprised between 1,500 and 10,000 mPas.
5. Method according to one of Claims 1 to 4, characterised in that the time between preparation of the composition and formation of the fibres passing through the orifices in the die is less than 1 minute.
6. Method according to one of Claims 1 to 5, characterised in that the atmosphere surrounding the die in the path of the fibres is heated by means of hot gas currents.
7. Method according to Claim 6, characterised in that the hot gas currents are blown at a speed of less than 20 m/s.
8. Method according to one of Claims 6 or 7, characterised in that the hot gas currents are blown at a temperature sufficient to avoid the fibres sticking.
9. Method according to one of Claims 1 to 8, in which the temperature of the fibres in the atmosphere surrounding the centrifugal die is raised to a temperature below that at which bubbles appear in the fibres.
10. Method according to Claim 9 in which the temperature of the fibres in the atmosphere surrounding the centrifugal die is at most 80° C.
11. Method according to Claim 10 in which the time taken by the fibres to pass along the path between the centrifuge and the receiving belt is between 0.1 and 2 seconds.
12. Method according to one of Claims 2 to 11 in which the catalyst consists of an equeous solution of a sulphuric, hydrochloric or phosphoric acid or mixtures of these acids.
13. Method according to Claim 12 in which the miscibility of the aqueous solution of the catalyst with the resin is improved by the addition of methanol.
14. Method according to any one of the preceding Claims, in which a fibring agent consisting of a long chain polyoxyolefin is introduced into the composition intended to form the fibres.
15. Method according to one of the preceding Claims in which a surface active agent is likewise introduced into the composition intended to form the fibres.
16. Method according to any one of the preceding Claims in which the fibres formed are furthermore subjected to a heat treatment at a temperature below the residual softening temperature for a time not exceeding 5 minutes.
17. Method according to Claim 16 in which the heat treatment is carried out at a gas temperature of between 100 and 150°C.
18. Method according to one of Claims 1 to 15 in which the fibres collected in the form of a felt are subjected to a thermal treatment at a temperature higher than the residual softening temperature.
19. Method according to Claim 18 in which the heat treatment is carried out at a temperature comprised between 200 and 240° C.
EP84400583A 1983-03-23 1984-03-22 Method for the preparation of phenoplast fibres Expired EP0122836B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8304737A FR2543169B1 (en) 1983-03-23 1983-03-23 PROCESS FOR PRODUCING PHENOPLAST FIBERS
FR8304737 1983-03-23

Publications (2)

Publication Number Publication Date
EP0122836A1 EP0122836A1 (en) 1984-10-24
EP0122836B1 true EP0122836B1 (en) 1987-03-18

Family

ID=9287133

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84400583A Expired EP0122836B1 (en) 1983-03-23 1984-03-22 Method for the preparation of phenoplast fibres

Country Status (5)

Country Link
US (1) US5055241A (en)
EP (1) EP0122836B1 (en)
JP (1) JPS59179811A (en)
DE (1) DE3462703D1 (en)
FR (1) FR2543169B1 (en)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2588255A1 (en) * 1985-10-09 1987-04-10 Saint Gobain Isover COMPOSITION FOR THE SIZING OF MINERAL FIBERS AND MINERAL FIBERS ENCOLLEES
JPH0735610B2 (en) * 1986-01-24 1995-04-19 三菱石油株式会社 Pitch-based carbon fiber centrifugal spinning device
FR2695413B3 (en) * 1992-09-09 1994-12-16 Saint Gobain Isover Device for the formation of phenoplast fibers.
EP0939148B1 (en) * 1995-03-03 2001-12-05 Twaron Products B.V. Centrifugal spinning process for optically anisotropic spinning solutions
US6001303A (en) * 1997-12-19 1999-12-14 Kimberly-Clark Worldwide, Inc. Process of making fibers
US6368533B1 (en) * 1997-12-22 2002-04-09 Kimberly-Clark Worldwide, Inc. Process for forming films, fibers and base webs from thermoset polymers
HUP0700795A2 (en) * 2007-12-10 2009-04-28 Miskolci Egyetem Coextrusion centrifugal apparatus to fibre formation
JP5458280B2 (en) * 2010-01-06 2014-04-02 パナソニック株式会社 Nanofiber manufacturing apparatus and manufacturing method
JP5322112B2 (en) * 2010-01-18 2013-10-23 パナソニック株式会社 Nanofiber manufacturing apparatus and manufacturing method
WO2014025794A1 (en) 2012-08-06 2014-02-13 Fiberio Technology Corporation Devices and methods for the production of microfibers and nanofibers in a controlled environment
DE102019003795A1 (en) * 2019-05-29 2020-12-03 Bb Engineering Gmbh Device and method for producing a fleece
CN111910272B (en) * 2020-06-29 2023-01-24 太原理工大学 Method for preparing phenolic fiber by melt-blown spinning

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4947613A (en) * 1971-09-08 1974-05-08
JPS5010408B2 (en) * 1971-11-06 1975-04-21
JPS5029817A (en) * 1973-07-19 1975-03-25
US4323524A (en) * 1977-03-11 1982-04-06 Imperial Chemical Industries Limited Production of fibres
GB1573116A (en) * 1977-03-11 1980-08-13 Ici Ltd Production of formaldehyde resin fibres by centrifugal spining
NZ187979A (en) * 1977-07-29 1982-05-31 Ici Ltd Centrifugal spinning of fibres from liquid
DE3066547D1 (en) * 1979-04-09 1984-03-22 Ici Plc Spinning process and apparatus
DE3060576D1 (en) * 1979-05-15 1982-08-12 Ici Plc Spinning process
JPS55163212A (en) * 1979-06-06 1980-12-19 Mitsui Petrochem Ind Ltd Production of phenolic resin fiber

Also Published As

Publication number Publication date
FR2543169B1 (en) 1986-03-28
FR2543169A1 (en) 1984-09-28
US5055241A (en) 1991-10-08
DE3462703D1 (en) 1987-04-23
JPS59179811A (en) 1984-10-12
EP0122836A1 (en) 1984-10-24
JPH059525B2 (en) 1993-02-05

Similar Documents

Publication Publication Date Title
EP0122836B1 (en) Method for the preparation of phenoplast fibres
EP0099801B1 (en) Process and device for the manufacture of a fibre fleece containing an additional product
EP0281447A1 (en) Process for producing thermoplastic polymer profiles by pultrusion, apparatus and products obtained
EP0140729A1 (en) Process and apparatus for the preparation of a chocolate paste
NO147491B (en) PROCEDURE FOR MANUFACTURING FIBERS FROM A HEAT-CURING FORMAL HEADPAR
EP0189354A1 (en) Production of mineral fibres
EP0091866B1 (en) Production of fibres by centrifugation
EP0308314A1 (en) Process for the ozone treatment of lignocellulosic materials, in particular paper pulps, and reactor for carrying out this process
EP0091381B1 (en) Manufacture of fibres by centrifuging and blowing
FR2497143A1 (en) METHOD AND DEVICE FOR MANUFACTURING POROUS PIPES
EP2791222B1 (en) Process for preparing polyamide granules and uses
CA2212921C (en) Method for making a glass mat and resulting product
FR2918365A1 (en) PROCESS FOR RECYCLING WATER FROM A PROCESS FOR PRODUCING AN INSULATING MATTRESS OF MINERAL FIBERS
FR2584105A1 (en) METHOD AND APPARATUS FOR MANUFACTURING A FELT OF CARBON FIBERS AND FELT OBTAINED BY THEIR IMPLEMENTATION
EP0588673B1 (en) Process for the production of polyaminoborazines
EP0371847A1 (en) Composite material based on mineral fibres, apparatus for making it and use of the composite material
FR2489207A1 (en) PROCESS FOR WET MIXING SILICONE COMPOSITIONS FOR MOLDING
CA2502333A1 (en) High-density glass fibre granules
EP0034548B1 (en) Apparatus for obtaining dispersions
EP0403347B1 (en) Mineral fibre composite useful for the manufacture of moulding articles
EP1123733B1 (en) Process and device for preparing wood-fibres pellets
JPH0437634A (en) Method and device for drying wet chopped strand
EP4087828B1 (en) Method for manufacturing insulation products based on mineral wool
FR2695413A1 (en) Device for the formation of phenoplast fibers.
FR2700556A1 (en) Apparatus for manufacturing filaments from a fusible material.

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): BE DE FR GB IT NL

17P Request for examination filed

Effective date: 19850401

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE DE FR GB IT NL

REF Corresponds to:

Ref document number: 3462703

Country of ref document: DE

Date of ref document: 19870423

ITF It: translation for a ep patent filed

Owner name: DR. ING. A. RACHELI & C.

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
ITTA It: last paid annual fee
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: BE

Payment date: 19921222

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19921224

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19930331

Year of fee payment: 10

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19940322

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Effective date: 19940331

BERE Be: lapsed

Owner name: ISOVER SAINT-GOBAIN

Effective date: 19940331

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19941001

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19940322

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19980305

Year of fee payment: 15

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19980307

Year of fee payment: 15

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19991130

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000101